Display device, display module, and electronic apparatus

文档序号：1382560 发布日期：2020-08-14 浏览：17次中文

阅读说明：本技术 显示装置、显示模块及电子设备 (Display device, display module, and electronic apparatus ) 是由丰高耕平渡边一德川岛进高桥圭楠纮慈中田昌孝佐藤亚美于 2018-12-25 设计创作，主要内容包括：提供一种开口率高的液晶显示装置。该显示装置在像素中包括晶体管、第一绝缘层、第二绝缘层、第三绝缘层、第一导电层、像素电极、公共电极以及液晶层。第一绝缘层位于晶体管的沟道形成区域上。第一导电层位于第一绝缘层上。第二绝缘层位于晶体管、第一绝缘层及第一导电层上。像素电极位于第二绝缘层上,第三绝缘层位于像素电极上,公共电极位于第三绝缘层上,液晶层位于公共电极上。公共电极具有隔着像素电极与第一导电层重叠的区域。像素包括像素电极与晶体管电连接的第一连接部及第一导电层与公共电极电连接的第二连接部。第一导电层、像素电极及公共电极都具有使可见光透过的功能。(A liquid crystal display device having a high aperture ratio is provided. The display device includes a transistor, a first insulating layer, a second insulating layer, a third insulating layer, a first conductive layer, a pixel electrode, a common electrode, and a liquid crystal layer in a pixel. The first insulating layer is located on a channel formation region of the transistor. The first conductive layer is located on the first insulating layer. The second insulating layer is located on the transistor, the first insulating layer and the first conducting layer. The pixel electrode is positioned on the second insulating layer, the third insulating layer is positioned on the pixel electrode, the common electrode is positioned on the third insulating layer, and the liquid crystal layer is positioned on the common electrode. The common electrode has a region overlapping with the first conductive layer with the pixel electrode interposed therebetween. The pixel comprises a first connecting part and a second connecting part, wherein the pixel electrode is electrically connected with the transistor, and the first connecting part is electrically connected with the common electrode through the first conducting layer. The first conductive layer, the pixel electrode, and the common electrode all have a function of transmitting visible light.)

1. A display device, comprising:

the number of the pixels is set to be,

wherein the pixel includes a first transistor, a first insulating layer, a second insulating layer, a third insulating layer, a first conductive layer, a pixel electrode, a common electrode, and a liquid crystal layer,

the first insulating layer is located over a channel formation region of the first transistor,

the first conductive layer is on the first insulating layer,

the second insulating layer is over the first transistor, the first insulating layer, and the first conductive layer,

the pixel electrode is positioned on the second insulating layer,

the third insulating layer is on the pixel electrode,

the common electrode is located on the third insulating layer,

the liquid crystal layer is positioned on the common electrode,

the common electrode has a region overlapping with the first conductive layer with the pixel electrode interposed therebetween,

the pixel further comprises a first connection portion and a second connection portion,

in the first connection portion, the pixel electrode is electrically connected to the first transistor,

in the second connection portion, the first conductive layer is electrically connected to the common electrode,

the first conductive layer, the pixel electrode, and the common electrode all have a function of transmitting visible light.

2. The display device according to claim 1, wherein the first and second light sources are arranged in a matrix,

wherein in the second connection portion, the first conductive layer has a region in contact with the common electrode.

3. A display device, comprising:

the number of the pixels is set to be,

wherein the pixel includes a first transistor, a second transistor, a first insulating layer, a second insulating layer, a third insulating layer, a first conductive layer, a pixel electrode, a common electrode, and a liquid crystal layer,

the first insulating layer is located over a channel formation region of the first transistor,

the first conductive layer is on the first insulating layer,

the second insulating layer is over the first transistor, the second transistor, the first insulating layer, and the first conductive layer,

the pixel electrode is positioned on the second insulating layer,

the third insulating layer is on the pixel electrode,

the common electrode is located on the third insulating layer,

the liquid crystal layer is positioned on the common electrode,

the common electrode has a region overlapping with the first conductive layer with the pixel electrode interposed therebetween,

the pixel further comprises a first connection portion and a second connection portion,

in the first connection portion, the pixel electrode is electrically connected to the first transistor,

in the second connection portion, the first conductive layer is electrically connected to the second transistor,

the first conductive layer, the pixel electrode, and the common electrode all have a function of transmitting visible light.

4. The display device according to any one of claims 1 to 3,

wherein the first transistor has a function of transmitting visible light in the first connection portion.

5. The display device according to any one of claims 1 to 4,

wherein the pixel further comprises a second conductive layer,

the second conductive layer is located on the first insulating layer,

the first conductive layer and the second conductive layer comprise the same material,

and in the first connection portion, the pixel electrode has a region in contact with the second conductive layer, and the second conductive layer has a region in contact with a source or a drain of the first transistor.

6. The display device according to claim 5, wherein the first and second light sources are arranged in a matrix,

wherein a source or a drain of the first transistor has a function of transmitting visible light.

7. The display device according to any one of claims 1 to 6,

wherein the first transistor comprises a gate on the first insulating layer,

the first insulating layer is used as a gate insulating layer of the first transistor,

and the gate and the first conductive layer comprise the same material.

8. The display device according to any one of claims 1 to 7,

wherein the first insulating layer is located over the first transistor.

9. The display device according to any one of claims 1 to 8,

wherein an area of a region where the pixel electrode overlaps the first conductive layer is larger than an area of a region where the pixel electrode overlaps the common electrode.

10. The display device according to any one of claims 1 to 9,

wherein a thickness of the second insulating layer between the first conductive layer and the pixel electrode is smaller than a thickness of the third insulating layer between the pixel electrode and the common electrode.

11. The display device according to any one of claims 1 to 10,

the display device has a function of displaying by using a field sequential driving method.

12. The display device according to claim 11, wherein the display device is a liquid crystal display device,

wherein the liquid crystal layer comprises a liquid crystal material,

and the rotational viscosity coefficient of the liquid crystal material is 10 mPasec or more and 150 mPasec or less.

13. A display module, comprising:

the display device of any one of claims 1 to 12; and

a connector or an integrated circuit.

14. An electronic device, comprising:

a display module as claimed in claim 13; and

an antenna, a battery, a housing, a camera, a speaker, a microphone, or an operation button.

Technical Field

One embodiment of the present invention relates to a liquid crystal display device, a display module, and an electronic apparatus.

Note that one embodiment of the present invention is not limited to the above-described technical field. Examples of technical fields of one embodiment of the present invention include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, an illumination device, an input device (e.g., a touch sensor), an input/output device (e.g., a touch panel), and a method for driving or manufacturing the above-described devices.

Background

Flat panel displays typified by liquid crystal display devices and light emitting display devices are widely used as display devices. Although silicon is mainly used as a semiconductor material for transistors constituting these display devices, in recent years, a technique of using a transistor using a metal oxide for a pixel of a display device has been developed.

Patent documents 1 and 2 disclose techniques in which a transistor using a metal oxide as a semiconductor material is used as a switching element of a pixel of a display device.

In addition, patent document 3 discloses a memory device having a structure in which a transistor with an extremely low off-state current is used for a memory cell.

[ Prior Art document ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. 2007-123861

[ patent document 2] Japanese patent application laid-open No. 2007-and 96055

[ patent document 3] Japanese patent application laid-open No. 2011-119674

Disclosure of Invention

Technical problem to be solved by the invention

An object of one embodiment of the present invention is to provide a liquid crystal display device having a high aperture ratio. Alternatively, it is an object of one embodiment of the present invention to provide a liquid crystal display device with low power consumption. Alternatively, it is an object of one embodiment of the present invention to provide a high-resolution liquid crystal display device. Alternatively, it is an object of one embodiment of the present invention to provide a liquid crystal display device with high reliability. Alternatively, it is an object of one embodiment of the present invention to provide a liquid crystal display device which can stably operate in a wide temperature range.

Note that the description of these objects does not hinder the existence of other objects. It is not necessary for one embodiment of the invention to achieve all of the above objectives. Objects other than the above-described objects can be extracted from the descriptions of the specification, the drawings, and the claims.

Means for solving the problems

A display device according to one embodiment of the present invention includes a first transistor, a first insulating layer, a second insulating layer, a third insulating layer, a first conductive layer, a pixel electrode, a common electrode, and a liquid crystal layer in a pixel. The first insulating layer is located on a channel formation region of the first transistor. The first conductive layer is located on the first insulating layer. The second insulating layer is located on the first transistor, the first insulating layer and the first conducting layer. The pixel electrode is positioned on the second insulating layer. The third insulating layer is located on the pixel electrode. The common electrode is located on the third insulating layer. The liquid crystal layer is located on the common electrode. The common electrode has a region overlapping with the first conductive layer with the pixel electrode interposed therebetween. The pixel further comprises a first connecting part and a second connecting part. In the first connection portion, the pixel electrode is electrically connected to the first transistor. In the second connection portion, the first conductive layer is electrically connected to the common electrode. The first conductive layer, the pixel electrode, and the common electrode all have a function of transmitting visible light. In the first connection portion, the first transistor preferably has a function of transmitting visible light.

In the second connection portion, the first conductive layer preferably has a region in contact with the common electrode.

Alternatively, a display device according to one embodiment of the present invention includes a first transistor, a second transistor, a first insulating layer, a second insulating layer, a third insulating layer, a first conductive layer, a pixel electrode, a common electrode, and a liquid crystal layer in a pixel. The first insulating layer is located on a channel formation region of the first transistor. The first conductive layer is located on the first insulating layer. The second insulating layer is located on the first transistor, the second transistor, the first insulating layer and the first conductive layer. The pixel electrode is positioned on the second insulating layer. The third insulating layer is located on the pixel electrode. The common electrode is located on the third insulating layer. The liquid crystal layer is located on the common electrode. The common electrode has a region overlapping with the first conductive layer with the pixel electrode interposed therebetween. The pixel further comprises a first connecting part and a second connecting part. In the first connection portion, the pixel electrode is electrically connected to the first transistor. In the second connection portion, the first conductive layer is electrically connected to the second transistor. The first conductive layer, the pixel electrode, and the common electrode all have a function of transmitting visible light. In the first connection portion, the first transistor preferably has a function of transmitting visible light.

The pixel may further include a second conductive layer. The second conductive layer is located on the first insulating layer. The first conductive layer and the second conductive layer can be formed using the same process and the same material. In the first connection portion, it is preferable that the pixel electrode has a region in contact with the second conductive layer, and the second conductive layer has a region in contact with a source or a drain of the first transistor. The source or the drain of the first transistor preferably has a function of transmitting visible light.

The first transistor may also include a gate on the first insulating layer. At this time, the first insulating layer is used as a gate insulating layer of the first transistor. The gate electrode and the first conductive layer can be formed using the same process and the same material. Alternatively, the first insulating layer may be provided over the first transistor.

The area of the region where the pixel electrode overlaps the first conductive layer is preferably larger than the area of the region where the pixel electrode overlaps the common electrode.

The thickness of the second insulating layer between the first conductive layer and the pixel electrode is preferably smaller than the thickness of the third insulating layer between the pixel electrode and the common electrode.

The display device according to one embodiment of the present invention preferably has a function of displaying by a field sequential driving method. In this case, the liquid crystal layer preferably contains a liquid crystal material having a rotational viscosity coefficient of 10mPa · sec or more and 150mPa · sec or less.

One embodiment of the present invention is a module including a display device having any of the above-described structures, the module being mounted with a connector such as a Flexible printed circuit board (FPC) or a TCP (Tape carrier package), or an Integrated Circuit (IC) mounted with a COG (Chip On Glass) system or a COF (Chip On Film) system.

One embodiment of the present invention is an electronic device including: the above module; and at least one of an antenna, a battery, a casing, a camera, a speaker, a microphone, and an operation button.

Effects of the invention

According to one embodiment of the present invention, a liquid crystal display device with a high aperture ratio can be provided. Alternatively, according to an embodiment of the present invention, a liquid crystal display device with low power consumption can be provided. Alternatively, according to an embodiment of the present invention, a high-resolution liquid crystal display device can be provided. Alternatively, according to an embodiment of the present invention, a highly reliable liquid crystal display device can be provided. Alternatively, according to an embodiment of the present invention, a liquid crystal display device which can stably operate in a wide temperature range can be provided.

Note that the description of these effects does not hinder the existence of other effects. One embodiment of the present invention does not need to achieve all of the above effects. Effects other than the above-described effects can be extracted from the descriptions of the specification, the drawings, and the claims.

Brief description of the drawings

FIG. 1 is a cross-sectional view showing an example of a display device.

Fig. 2 shows a circuit diagram of an example of a pixel.

FIG. 3 is a plan view showing an example of a display device.

FIG. 4 is a plan view showing an example of a pixel.

FIG. 5 is a cross-sectional view showing an example of a display device.

FIG. 6 is a cross-sectional view showing an example of a display device.

FIG. 7 is a cross-sectional view showing an example of a display device.

Fig. 8 (a) shows a circuit diagram of an example of a pixel. (B) And (C) a timing chart.

FIG. 9 is a plan view showing an example of a pixel.

FIG. 10 is a cross-sectional view showing an example of a display device.

FIG. 11 is a cross-sectional view showing an example of a display device.

FIG. 12 is a cross-sectional view showing an example of a display device.

FIG. 13 is a plan view showing an example of a pixel.

FIG. 14 is a cross-sectional view showing an example of a display device.

FIG. 15 is a plan view showing an example of a pixel.

FIG. 16 is a cross-sectional view showing an example of a display device.

Fig. 17 is a plan view showing an example of a pixel.

FIG. 18 is a cross-sectional view showing an example of a display device.

Fig. 19 is a plan view showing an example of a pixel.

FIG. 20 is a cross-sectional view showing an example of a display device.

FIG. 21 is a plan view showing an example of a pixel.

FIG. 22 is a cross-sectional view showing an example of a display device.

FIG. 23 is a plan view showing an example of a pixel.

FIG. 24 is a cross-sectional view showing an example of a display device.

[ FIG. 25] is a diagram showing an example of an electronic device.

Fig. 26 is a diagram showing an example of an electronic device.

Fig. 27 is a photograph showing the display result of the display device of the embodiment.

Modes for carrying out the invention

The embodiments are described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following description, and those skilled in the art can easily understand that the form and details thereof can be changed into various forms without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments shown below.

Note that in the following description of the present invention, the same reference numerals are used in common in different drawings to denote the same portions or portions having the same functions, and repetitive description thereof will be omitted. In addition, when parts having the same functions are denoted by the same hatching, the same reference numerals are sometimes used without particular addition of a reference numeral.

For convenience of understanding, the positions, sizes, ranges, and the like of the respective components shown in the drawings may not represent actual positions, sizes, ranges, and the like. Accordingly, the disclosed invention is not necessarily limited to the positions, sizes, ranges, etc., disclosed in the drawings.

In addition, the "film" and the "layer" may be exchanged with each other depending on the situation or state. For example, the "conductive layer" may be converted to a "conductive film". In addition, the "insulating film" may be converted into an "insulating layer".

(embodiment mode 1)

In this embodiment, a display device according to one embodiment of the present invention is described with reference to fig. 1 to 12.

Structural example of display device 1

Fig. 1A shows a cross-sectional view of a transmissive liquid crystal display device. The liquid crystal display device shown in fig. 1A includes a substrate 31, a transistor 102, an insulating layer 215, a conductive layer 46, an insulating layer 44, a pixel electrode 41, an insulating layer 45, a common electrode 43, a liquid crystal layer 42, and a substrate 32.

Transistor 102 is located on substrate 31. An insulating layer 215 is over the transistor 102. The conductive layer 46 is located on the insulating layer 215. Insulating layer 44 is over transistor 102, insulating layer 215, and conductive layer 46. The pixel electrode 41 is located on the insulating layer 44. The insulating layer 45 is positioned on the pixel electrode 41. The common electrode 43 is located on the insulating layer 45. The liquid crystal layer 42 is positioned on the common electrode 43. The common electrode 43 has a region overlapping with the conductive layer 46 with the pixel electrode 41 interposed therebetween. The pixel electrode 41 is electrically connected to a source or a drain of the transistor 102. The conductive layer 46, the pixel electrode 41, and the common electrode 43 all have a function of transmitting visible light.

The liquid crystal display device of the present embodiment is configured such that the pixel electrode 41 and the common electrode 43 are stacked with the insulating layer 45 interposed therebetween, and operates in an FFS (Fringe Field Switching) mode. The pixel electrode 41, the liquid crystal layer 42, and the common electrode 43 can be used as the liquid crystal element 106.

The conductive layer 46, the insulating layer 44, and the pixel electrode 41 can be used as one capacitive element 104. Further, the pixel electrode 41, the insulating layer 45, and the common electrode 43 can be used as one capacitor element 105. As described above, the liquid crystal display device of the present embodiment includes two capacitor elements in a pixel. Therefore, the holding capacitance of the pixel can be increased.

In addition, both the two capacitor elements are formed using a material that transmits visible light, and have regions that overlap each other. Thus, the pixel can achieve both a high aperture ratio and a large holding capacitance.

By increasing the aperture ratio of the transmissive liquid crystal display device (which may also be referred to as the aperture ratio of the pixel), the resolution of the liquid crystal display device can be increased. In addition, by increasing the aperture ratio, the light extraction efficiency (or the transmittance of the pixel) can be increased. Thus, power consumption of the liquid crystal display device can be reduced.

By increasing the holding capacity of the pixel, stable display can be performed even if the leakage current of the liquid crystal element or the like is large. In addition, a liquid crystal material with a large capacity can be driven. This can expand the range of selection of liquid crystal materials.

By increasing the holding capacity of the pixel, the gradation of the pixel can be held for a long time. Specifically, by increasing the holding capacity of the pixel, the image signal written in the previous period can be held without rewriting the image signal in each frame period, and the gradation of the pixel can be held in a period of several frames or several tens of frames, for example.

The capacitance of the capacitive element 104 is preferably larger than that of the capacitive element 105. For example, the area of the region where the pixel electrode 41 overlaps the conductive layer 46 is preferably larger than the area of the region where the pixel electrode 41 overlaps the common electrode 43. Further, the thickness T1 of the insulating layer 44 between the conductive layer 46 and the pixel electrode 41 is preferably smaller than the thickness T2 of the insulating layer 45 between the pixel electrode 41 and the common electrode 43.

The structure of the display device of the present embodiment can also be applied to a touch panel. Fig. 1B is an example of mounting the touch sensor TC to the display device shown in fig. 1A. By disposing the touch sensor TC at a position close to the display surface of the display device, the sensitivity of the touch sensor TC can be improved.

The touch panel according to one embodiment of the present invention includes no limitation on the sensing elements (also referred to as sensor elements). Various sensors capable of sensing the proximity or contact of a sensing object such as a finger, a stylus pen, etc. may be used as the sensing element.

For example, various types of sensors such as a capacitance type, a resistance film type, a surface acoustic wave type, an infrared type, an optical type, and a pressure-sensitive type can be used.

The capacitance type includes a surface type capacitance type, a projection type capacitance type, and the like. The projection type capacitance includes a self capacitance and a mutual capacitance. When using mutual capacitance, multipoint sensing can be performed simultaneously, and is therefore preferred.

A touch panel according to one embodiment of the present invention can have various structures such as a structure in which a display device and a sensor element which are manufactured separately are bonded to each other, and a structure in which an electrode or the like constituting a sensor element is provided over one or both of a substrate supporting a display element and a counter substrate.

Structural example of display device 2

A structure example of a display device including one transistor and two capacitor elements in a pixel is described with reference to fig. 2 to 7.

Circuits (circuits)

Fig. 2A and 2B show circuit diagrams of the pixel 11 a.

The pixel 11a shown in fig. 2A and 2B includes a transistor 102, a capacitor 104, a capacitor 105, and a liquid crystal element 106. The pixel 11a is connected to the wiring 121 and the wiring 124.

Fig. 2A shows an example in which the transistor 102 does not include a back gate, and fig. 2B shows an example in which the transistor 102 includes a back gate. Although fig. 2B shows an example in which the back gate is electrically connected to the gate, the connection manner of the back gate is not limited thereto.

One of a source and a drain of the transistor 102 is electrically connected to one electrode of the capacitor element 104, one electrode of the capacitor element 105, and one electrode of the liquid crystal element 106.

Here, a node connected to one of the source and the drain of the transistor 102, one electrode of the capacitor 104, one electrode of the capacitor 105, and one electrode of the liquid crystal element 106 is referred to as a node NA.

A gate of the transistor 102 is electrically connected to a wiring 121. The other of the source and the drain of the transistor 102 is electrically connected to a wiring 124. The other electrode of the capacitor element 104, the other electrode of the capacitor element 105, and the other electrode of the liquid crystal element 106 are electrically connected to a common wiring VCOM. An arbitrary potential can be supplied to the common wiring VCOM.

The wiring 121 may be referred to as a scan line and has a function of controlling the operation of a transistor. The wiring 124 has a function of a signal line supplying an image signal.

By using a transistor with extremely low off-state current as the transistor 102, the potential of the node NA can be held for a long time. As the transistor, for example, a transistor using a metal oxide for a channel formation region (hereinafter referred to as an OS transistor) can be used.

Alternatively, a transistor including silicon in a channel formation region (hereinafter referred to as a Si transistor) may be used as a transistor included in a pixel. Examples of the Si transistor include a transistor containing amorphous silicon, a transistor containing crystalline silicon (typically, low-temperature polysilicon or single crystal silicon), and the like.

For example, when the image signal is rewritten for each frame period, an OS transistor or an Si transistor may be used. In the case where it is necessary to hold the potential of the node NA for a long time, an OS transistor is preferably used as compared with a Si transistor.

Overlook layout of display Module

Fig. 3 shows a top view of the display module.

The display module shown in fig. 3 includes a display device, an Integrated Circuit (IC) connected to the display device, and flexible printed circuit boards (FPCa, FPCb).

The display device includes a display region 100, a gate driver GD _ L, and a gate driver GD _ R.

The display area 100 includes a plurality of pixels 11 and has a function of displaying an image.

The pixels 11 may also be referred to as sub-pixels. For example, the display region 100 can display full color by configuring one pixel unit using a sub-pixel that represents red, a sub-pixel that represents green, and a sub-pixel that represents blue. Note that the colors presented by the subpixels are not limited to red, green, and blue. In the pixel unit, for example, sub-pixels that exhibit colors such as white, yellow, magenta, and cyan may be used. Note that in this specification and the like, a sub-pixel is sometimes simply referred to as a pixel.

The display device may be provided with one or more of a scanning line driver circuit (gate driver), a signal line driver circuit (source driver), and a touch sensor driver circuit. Further, one or more of these driving circuits may be provided outside the display device. The display device shown in fig. 3 is mounted with a gate driver and is provided with an IC including a source driver on the outside thereof.

One of the gate drivers GD _ L and GD _ R has a function of controlling the pixels in the odd-numbered rows, and the other has a function of controlling the pixels in the even-numbered rows. For example, the pixels in the mth row are connected to the scanning line GL _ m and controlled by the gate driver GD _ L. Further, the pixels in the (m + 1) th row are connected to the scanning line GL _ m +1 and controlled by the gate driver GD _ R. The pixel 11 electrically connected to the gate driver GD _ L and the pixel 11 electrically connected to the gate driver GD _ R are alternately connected to the signal line SL _ n of the nth column. By providing the gate drivers on the two sides facing each other, the distance between the wirings connected to one gate driver can be increased. In addition, when the gate driver is provided only on one side, the non-display area on the side of the side is enlarged. Thus, by providing the gate drivers on both sides, the non-display area on each side of the display device can be reduced, and the frame can be narrowed.

The gate drivers GD _ L and GD _ R are supplied with signals and power from the outside through the FPCa. The IC is supplied with signals and power from the outside through FPCb.

Overlook layout of pixels

Fig. 4A to 4C show top views of the pixels. Fig. 4A is a plan view of the stacked structure of the gate electrode 221 to the common electrode 43a as viewed from the common electrode 43a side. Fig. 4B is a plan view when the common electrode 43a is removed from the stacked structure of fig. 4A, and fig. 4C is a plan view when the common electrode 43a and the pixel electrode 41 are removed from the stacked structure of fig. 4A.

The common electrode 43a may have one or more slits, and may also have a top surface shape of a comb-tooth shape. The common electrode 43a shown in fig. 4A has a top surface shape provided with a plurality of slits. The pixel electrode 41 has both a region overlapping the common electrode 43a and a region not overlapping the common electrode 43 a. Both the regions are provided at positions overlapping the colored layer 39 (see fig. 5).

In addition, the pixel electrode 41 may have one or more slits, or may have a comb-tooth top surface shape. Since the area overlapping the common electrode 43a can be increased, the pixel electrode 41 having a large area is preferably formed. Thus, the pixel electrode 41 is preferably formed in an island shape without a slit.

Cross-sectional Structure of display Module

Fig. 5 shows a cross-sectional view of a display module. The cross-sectional structure of the pixel corresponds to the cross-sectional view between the dot-dash line a1-a2 shown in fig. 4A.

The display module shown in fig. 5 includes the display device 10, the polarizing plate 61, the polarizing plate 63, the backlight unit 30, the FPC172, and the like.

The light 35 emitted from the light source included in the backlight unit 30 is emitted to the outside of the display module through the polarizing plate 61, the display device 10, and the polarizing plate 63 in this order. As a material of these layers through which the light 35 transmits, a material that transmits visible light is used.

Since the display device 10 includes the colored layer 39, a color image can be displayed. Light outside a specified wavelength region among the light 35 emitted from the light source included in the backlight unit 30 is absorbed by the colored layer 39. Thus, for example, light emitted from a red pixel (sub-pixel) to the outside of the display module appears red, light emitted from a green sub-pixel (sub-pixel) to the outside of the display module appears green, and light emitted from a blue sub-pixel (sub-pixel) to the outside of the display module appears blue.

The display device 10 is an active matrix type liquid crystal display device using an FFS mode. The display device 10 is a transmissive liquid crystal display device.

The display device 10 includes a substrate 31, a substrate 32, a transistor 102, a conductive layer 46a, a conductive layer 46b, a conductive layer 46c, an insulating layer 44, an insulating layer 45, a pixel electrode 41, a liquid crystal layer 42, a common electrode 43a, a conductive layer 43b, a conductive layer 222e, an alignment film 133a, an alignment film 133b, an adhesive layer 141, a protective layer 135, a light-shielding layer 38, a colored layer 39, and the like.

Transistor 102 is located on substrate 31. The transistor 102 includes a gate electrode 221, a gate insulating layer 211, a semiconductor layer 231, a conductive layer 222a, a conductive layer 222b, an insulating layer 217, an insulating layer 218, an insulating layer 215, and a gate electrode 223. One of the conductive layer 222a and the conductive layer 222b is used as a source electrode, and the other is used as a drain electrode. The insulating layer 217, the insulating layer 218, and the insulating layer 215 are used as a gate insulating layer.

Here, a case where a metal oxide is used as the semiconductor layer 231 will be described as an example.

The gate insulating layer 211 and the insulating layer 217 which are in contact with the semiconductor layer 231 are preferably oxide insulating layers. In the case where the gate insulating layer 211 or the insulating layer 217 has a stacked-layer structure, a layer in contact with the semiconductor layer 231 is preferably at least an oxide insulating layer. This can suppress the generation of oxygen defects in the semiconductor layer 231, and can improve the reliability of the transistor.

The insulating layer 218 is preferably a nitride insulating layer. This can suppress the entry of impurities into the semiconductor layer 231, and can improve the reliability of the transistor.

The insulating layer 215 preferably has a planarizing function, and is preferably an organic insulating layer, for example. Note that the insulating layer 215 need not be formed, and the conductive layer 46a may be formed over and in contact with the insulating layer 218.

The conductive layer 46a is located on the insulating layer 215. Insulating layer 44 and insulating layer 45 are located on conductive layer 46 a. The common electrode 43a is located on the insulating layer 45. The common electrode 43a is electrically connected to the conductive layer 46 a. Specifically, the common electrode 43a is in contact with the conductive layer 46a through openings provided in the insulating layer 44 and the insulating layer 45.

The light-shielding layer 38 and the colored layer 39 are provided on the substrate 32, and a protective layer 135 covering the light-shielding layer 38 and the colored layer 39 is provided. The alignment film 133b is provided in contact with the protective layer 135. Further, an alignment film 133a is provided on the common electrode 43 a. The liquid crystal layer 42 is interposed between the alignment film 133a and the alignment film 133 b. The protective layer 135 can suppress diffusion of impurities contained in the colored layer 39, the light-shielding layer 38, and the like into the liquid crystal layer 42.

The substrate 31 and the substrate 32 are attached together by an adhesive layer 141.

The FPC172 is electrically connected to the conductive layer 222 e. Specifically, the FPC172 is in contact with the connector 242, the connector 242 is in contact with the conductive layer 43b, the conductive layer 43b is in contact with the conductive layer 46c, and the conductive layer 46c is in contact with the conductive layer 222 e. A conductive layer 43b is formed over the insulating layer 45, a conductive layer 46c is formed over the insulating layer 215, and a conductive layer 222e is formed over the gate insulating layer 211. The conductive layer 43b can be formed by the same process and material as the common electrode 43 a. The conductive layer 46c can be formed using the same process and material as the gate electrode 223, the conductive layer 46a, and the conductive layer 46 b. The conductive layer 222e can be formed using the same process and material as the conductive layers 222a and 222 b.

The conductive layer 46a, the insulating layer 44, and the pixel electrode 41 can be used as one capacitive element 104. Further, the pixel electrode 41, the insulating layer 45, and the common electrode 43a can be used as one capacitor element 105. As such, the display device 10 includes two capacitance elements in one pixel. Therefore, the holding capacitance of the pixel can be increased.

The capacitance of the capacitive element 104 is preferably larger than that of the capacitive element 105. Therefore, the area of the region where the pixel electrode 41 overlaps the conductive layer 46a is preferably larger than the area of the region where the pixel electrode 41 overlaps the common electrode 43 a. Further, the thickness of the insulating layer 44 between the conductive layer 46a and the pixel electrode 41 is preferably smaller than the thickness of the insulating layer 45 between the pixel electrode 41 and the common electrode 43 a.

Although fig. 5 shows an example in which the transistor 102 includes a back gate (the gate 223 in fig. 5), the transistor 102 may not include a back gate as shown in fig. 6. The transistor 102 shown in fig. 6 includes a gate electrode 221, a gate insulating layer 211, a semiconductor layer 231, a conductive layer 222a, and a conductive layer 222 b. The transistor 102 shown in fig. 6 is covered with an insulating layer 217, an insulating layer 218, and an insulating layer 215.

The display device 10 shown in fig. 7 is different from those shown in fig. 5 and 6 in the structure of the transistor 102.

The transistor 102 shown in fig. 7 includes a gate electrode 221, a gate insulating layer 211, a semiconductor layer 231, a conductive layer 222a, a conductive layer 222b, an insulating layer 212, an insulating layer 213, a gate insulating layer 225, and a gate electrode 223. One of the conductive layer 222a and the conductive layer 222b is used as a source electrode, and the other is used as a drain electrode. Transistor 102 is covered by insulating layer 214 and insulating layer 215.

The transistor 102 shown in fig. 7 includes gates above and below a channel. The two gates are preferably electrically connected. The transistor having a structure in which two gates are electrically connected can improve field effect mobility and can increase on-state current (on-state current) as compared with other transistors. As a result, a circuit capable of high-speed operation can be manufactured. Further, the occupied area of the circuit portion can be reduced. By using a transistor with a large on-state current, even when the number of wirings is increased when the display device is increased in size or resolution, signal delay of each wiring can be reduced, and display unevenness can be suppressed. Further, since the occupied area of the circuit portion can be reduced, the frame of the display device can be narrowed. In addition, by adopting such a structure, a transistor with high reliability can be realized.

The semiconductor layer 231 includes a pair of low-resistance regions 231n and a channel formation region 231i sandwiched between the pair of low-resistance regions 231 n.

The channel formation region 231i overlaps with the gate electrode 221 via the gate insulating layer 211, and overlaps with the gate electrode 223 via the gate insulating layer 225.

Here, a case where a metal oxide is used as the semiconductor layer 231 will be described as an example.

The gate insulating layer 211 and the gate insulating layer 225 in contact with the channel formation region 231i are preferably oxide insulating layers. In the case where the gate insulating layer 211 or the gate insulating layer 225 has a stacked-layer structure, a layer in contact with the channel formation region 231i is preferably at least an oxide insulating layer. This can suppress the generation of oxygen defects in the channel formation region 231i, and can improve the reliability of the transistor.

One or both of the insulating layer 213 and the insulating layer 214 are preferably nitride insulating layers. This can suppress the entry of impurities into the semiconductor layer 231, and can improve the reliability of the transistor.

The insulating layer 215 preferably has a planarizing function, and is preferably an organic insulating layer, for example. Note that one or both of the insulating layer 214 and the insulating layer 215 may not be formed.

The low-resistance region 231n has a lower resistivity than the channel formation region 231 i. The low-resistance region 231n is a region in the semiconductor layer 231, which is in contact with the insulating layer 212. Here, the insulating layer 212 preferably contains nitrogen or hydrogen. Therefore, nitrogen or hydrogen in the insulating layer 212 enters the low-resistance region 231n, whereby the carrier concentration of the low-resistance region 231n can be increased. Alternatively, the low-resistance region 231n may be formed by adding an impurity using the gate electrode 223 as a mask. Examples of the impurities include hydrogen, helium, neon, argon, fluorine, nitrogen, phosphorus, arsenic, antimony, boron, aluminum, magnesium, and silicon, and the impurities can be added by an ion implantation method or an ion doping method. In addition to the impurities, the low-resistance region 231n may be formed by adding indium or the like which is one of the constituent elements of the semiconductor layer 231. By adding indium, the indium concentration of the low-resistance region 231n may be higher than that of the channel formation region 231 i.

After the gate insulating layer 235 and the gate electrode 233 are formed, the first layer is formed so as to be in contact with a region of the semiconductor layer 231, and heat treatment is performed to reduce the resistance of the region, whereby the low-resistance region 231n can be formed.

As the first layer, a film containing at least one of metal elements such as aluminum, titanium, tantalum, tungsten, chromium, and ruthenium can be used. In particular, at least one of aluminum, titanium, tantalum, and tungsten is preferably contained. Alternatively, a nitride containing at least one of the above metal elements or an oxide containing at least one of the above metal elements may be suitably used. In particular, a metal film such as a tungsten film or a titanium film, a nitride film such as a titanium aluminum nitride film, a titanium nitride film, or an aluminum nitride film, or an oxide film such as a titanium aluminum oxide film can be used as appropriate.

The thickness of the first layer may be, for example, 0.5nm or more and 20nm or less, preferably 0.5nm or more and 15nm or less, more preferably 0.5nm or more and 10nm or less, and still more preferably 1nm or more and 6nm or less. Typically, it may be about 5nm or about 2 nm. Even with such a thin first layer, the resistance of the semiconductor layer 231 can be sufficiently reduced.

It is important that the carrier density of the low-resistance region 231n is higher than that of the channel forming region 231 i. For example, the low-resistance region 231n may be a region containing more hydrogen than the channel formation region 231i or a region containing more oxygen defects than the channel formation region 231 i. Oxygen defects in the oxide semiconductor are bonded to hydrogen atoms to become a carrier generation source.

By performing the heat treatment in a state where the first layer is provided in contact with a region of a part of the semiconductor layer 231, oxygen in the region is drawn into the first layer, and thus, more oxygen defects can be formed in the region. This makes it possible to form the low-resistance region 231n having an extremely low resistance.

The low-resistance region 231n thus formed has a feature that it is not easy to increase the resistance in the subsequent process. For example, even when a heating process is performed in an atmosphere containing oxygen, or a film formation process is performed in an atmosphere containing oxygen, the conductivity of the low-resistance region 231n does not decrease, and thus a transistor having good electrical characteristics and high reliability can be realized.

When the first layer after the heat treatment has conductivity, it is preferable to remove the first layer after the heat treatment. On the other hand, when the first layer has an insulating property, it can be used as a protective insulating film by leaving the first layer.

Structural example of display device 3

A structure example of a display device including two transistors and two capacitance elements in a pixel is described with reference to fig. 8 to 12.

A display device according to one embodiment of the present invention has a function of adding a correction signal to an image signal.

The correction signal is added to the image signal by capacitive coupling and supplied to the liquid crystal element. Thereby, the liquid crystal element can display a corrected image. By this correction, for example, the liquid crystal element can express more gradations than can be expressed when only the image signal is used.

In addition, by this correction, the liquid crystal element can be driven at a voltage higher than the output voltage of the source driver. Since the voltage supplied to the liquid crystal element can be converted to a desired value in the pixel, an existing source driver can be used without requiring cost or the like due to a new source driver. In addition, the output voltage of the source driver can be suppressed from rising, and the power consumption of the source driver can be reduced.

By driving the liquid crystal element with high voltage, the display device can be used in a wide temperature range, and display with high reliability can be performed in both a low-temperature environment and a high-temperature environment. For example, the display device can be used as a display device for a vehicle or a camera.

Further, since the liquid crystal element can be driven at a high voltage, a liquid crystal material having a high driving voltage such as a liquid crystal exhibiting a blue phase can be used, and thus the selection range of the liquid crystal material can be widened.

In addition, since the liquid crystal element can be driven at a high voltage, the response speed of the liquid crystal can be improved by employing overdrive for changing the orientation of the liquid crystal rapidly by temporarily setting the voltage applied to the liquid crystal element to a high level.

In addition, burn-in of display can be reduced by driving the liquid crystal element with high voltage.

The correction signal is generated by, for example, an external device and written in each pixel. The correction signal may be generated in real time by an external device, or may be generated by reading the correction signal stored in the recording medium and synchronizing it with the image signal.

In the display device according to one embodiment of the present invention, a new image signal can be generated in the pixel to which the correction signal is supplied without changing the supplied image signal. The burden on the external device can be reduced as compared with the case where a new image signal itself is generated using the external device. Further, an operation of generating a new image signal can be performed in a pixel with a small number of steps, and the operation can be performed even in a display device having a large number of pixels and a short horizontal period.

Circuits (circuits)

Fig. 8A shows a circuit diagram of the pixel 11 b.

The pixel 11b includes a transistor 101, a transistor 102, a capacitor 104, a capacitor 105, and a liquid crystal element 106.

One of a source and a drain of the transistor 101 is electrically connected to one electrode of the capacitor element 104. The other electrode of the capacitor element 104 is electrically connected to one of a source and a drain of the transistor 102, one electrode of the capacitor element 105, and one electrode of the liquid crystal element 106.

Here, a node connected to one of the source and the drain of the transistor 101 and one electrode of the capacitor element 104 is referred to as a node NS. A node connected to the other electrode of the capacitor element 104, one of the source and the drain of the transistor 102, one electrode of the capacitor element 105, and one electrode of the liquid crystal element 106 is referred to as a node NA.

A gate of the transistor 101 is electrically connected to a wiring 122. A gate of the transistor 102 is electrically connected to a wiring 121. The other of the source and the drain of the transistor 101 is electrically connected to the wiring 125. The other of the source and the drain of the transistor 102 is electrically connected to a wiring 124.

The other electrode of the capacitor element 105 and the other electrode of the liquid crystal element 106 are both electrically connected to a common wiring VCOM. An arbitrary potential can be supplied to the common wiring VCOM.

Each of the wirings 121 and 122 can be referred to as a scan line, and has a function of controlling the operation of a transistor. The wiring 125 has a function of a signal line supplying an image signal. The wiring 124 has a function of a signal line for writing data to the node NA.

Although each transistor shown in fig. 8A includes a back gate electrically connected to a gate, the connection manner of the back gate is not limited thereto. In addition, the transistor may not be provided with a back gate.

By making the transistor 101 non-conductive, the potential of the node NS can be held. Further, the potential of the node NA can be held by turning the transistor 102 into a non-conductive state. Further, by supplying a predetermined potential to the node NS through the transistor 101 in a state where the transistor 102 is in a non-conductive state, the potential of the node NA can be changed in accordance with a change in the potential of the node NS by capacitive coupling through the capacitive element 104.

In the pixel 11b, the correction signal written from the wiring 124 to the node NA is capacitively coupled with the image signal supplied from the wiring 125, and is supplied to the liquid crystal element 106. Thereby, the liquid crystal element 106 can display the corrected image.

By using a transistor with extremely low off-state current as the transistor 101, the potential of the node NS can be held for a long time. Similarly, by using a transistor with extremely low off-state current as the transistor 102, the potential of the node NA can be held for a long time. As a transistor with extremely low off-state current, an OS transistor can be given, for example. In addition, a Si transistor may be used as a transistor included in a pixel. Alternatively, both an OS transistor and an Si transistor may be used.

For example, when the correction signal and the image signal are rewritten for each frame period, an OS transistor or an Si transistor can be used as the transistor 101 and the transistor 102. When it is necessary to hold the potential of the node NS or the node NA for a long time, an OS transistor is preferably used as the transistor 101 and the transistor 102 as compared with an Si transistor.

Timing charts

The operation of writing the correction signal (Vp) into the node NM in the pixel 11B will be described with reference to the timing chart shown in fig. 8B. In the case of aiming at correction of the image signal (Vs), it is preferable to write the correction signal Vp for each frame. Note that although any of a positive signal and a negative signal can be used as the correction signal (Vp) supplied to the wiring 124, a case where a positive signal is supplied is described here. In the following description, "H" represents a high potential, and "L" represents a low potential.

At time T1, when the potential of the wiring 121 is "H", the potential of the wiring 122 is "L", the potential of the wiring 124 is "L", and the potential of the wiring 125 is "L", the transistor 102 is turned on, and the potential of the node NA is set to the potential of the wiring 124. At this time, by setting the potential of the wiring 124 to a reset potential (for example, "L"), the operation of the liquid crystal element 106 can be reset.

Note that the display operation of the liquid crystal element 106 of the previous frame is performed before time T1.

At time T2, when the potential of the wiring 121 is "L", the potential of the wiring 122 is "H", the potential of the wiring 124 is "Vp", and the potential of the wiring 125 is "L", the transistor 101 is turned on, and the potential of the other electrode of the capacitor element 104 is "L". This operation is a reset operation performed before capacitive coupling.

At time T3, the potential of the wiring 124 (correction signal (Vp)) is written into the node NA by setting the potential of the wiring 121 to "H", the potential of the wiring 122 to "H", the potential of the wiring 124 to "Vp", and the potential of the wiring 125 to "L".

At time T4, when the potential of the wiring 121 is "L", the potential of the wiring 122 is "H", the potential of the wiring 124 is "Vp", and the potential of the wiring 125 is "L", the transistor 102 is turned off, and the correction signal (Vp) is held at the node NA.

At time T5, when the potential of the wiring 121, the potential of the wiring 122, the potential of the wiring 125, and the potential of the wiring 126 are set to "L", the transistor 101 is turned off, and the writing operation of the correction signal (Vp) is ended.

Next, the operation of correcting the image signal (Vs) in the pixel 11b and the operation of displaying the liquid crystal element 106 will be described with reference to the timing chart shown in fig. 8C. Note that the wiring 125 is supplied with a desired potential at an appropriate timing.

At time T11, when the potential of the wiring 121 is "L", the potential of the wiring 122 is "H", and the potential of the wiring 124 is "L", the transistor 101 is turned on, and the potential of the wiring 125 is added to the potential of the node NA by capacitive coupling of the capacitive element 104. That is, the node NA becomes the potential (Vs + Vp)' of the image signal (Vs) plus the correction signal (Vp). Note that the potential (Vs + Vp)' also includes potential variation due to capacitive coupling of capacitance between wirings, and the like.

At time T12, when the potential of the wiring 121, the potential of the wiring 122, and the potential of the wiring 124 are set to "L", the transistor 101 is turned off, and the potential (Vs + Vp)' is held at the node NM. Then, the liquid crystal element 106 performs a display operation based on the potential.

The above description is made of the correction operation of the image data (Vs) and the display operation of the liquid crystal element 106. Note that the writing operation of the correction signal (Vp) and the input operation of the image signal (Vs) described above may be performed continuously, or the correction signal (Vp) may be written to all the pixels before the input operation of the image signal (Vs) is performed.

When the correction operation is not performed, the display operation of the liquid crystal element 106 can be performed by supplying image data to the wiring 124 and controlling conduction/non-conduction of the transistor 102. At this time, the transistor 101 may be constantly in a non-conductive state, or the transistor 101 may be constantly in a conductive state in a state where a constant potential is supplied to the wiring 125.

Overlook layout of pixels

Fig. 9A to 9C show top views of pixels. Fig. 9A is a plan view of the stacked structure of the gate electrode 221a and the gate electrode 221b to the common electrode 43a when viewed from the common electrode 43a side. Fig. 9B is a plan view when the common electrode 43a is removed from the stacked structure of fig. 9A, and fig. 9C is a plan view when the common electrode 43a and the pixel electrode 41 are removed from the stacked structure of fig. 9A.

Cross-sectional Structure of display Module

Fig. 10 shows a cross-sectional view of a display module. The cross-sectional structure of the pixel corresponds to a cross-sectional view between the dot-dash lines B1-B2 shown in fig. 9A.

The display module shown in fig. 10 includes the display device 10, the polarizing plate 61, the polarizing plate 63, the backlight unit 30, the FPC172, and the like.

The display device 10 includes a substrate 31, a substrate 32, a transistor 102, a conductive layer 46a, a conductive layer 46b, an insulating layer 44, an insulating layer 45, a pixel electrode 41, a liquid crystal layer 42, a common electrode 43a, a conductive layer 43b, a conductive layer 222e, an alignment film 133a, an alignment film 133b, an adhesive layer 141, a protective layer 135, a light-shielding layer 38, a coloring layer 39, and the like.

Transistor 101 and transistor 102 are located over substrate 31. The transistor 102 includes a gate electrode 221a, a gate insulating layer 211, a semiconductor layer 231a, a conductive layer 222b, an insulating layer 212, an insulating layer 213, a gate insulating layer 225a, and a gate electrode 223 a. The transistor 101 includes a gate electrode 221b, a gate insulating layer 211, a semiconductor layer 231b, a conductive layer 222c, a conductive layer 222d, an insulating layer 212, an insulating layer 213, a gate insulating layer 225b, and a gate electrode 223 b. Since the structures of the transistor 101 and the transistor 102 in fig. 10 are the same as those of the transistor 102 in fig. 7, detailed description thereof is omitted.

The conductive layer 46a is located on the insulating layer 215. Conductive layer 46a is electrically connected to conductive layer 222 c. Specifically, the conductive layer 46a is in contact with the conductive layer 222c through openings provided in the insulating layer 214 and the insulating layer 215.

The substrate 31 and the substrate 32 are attached together by an adhesive layer 141.

Although fig. 10 shows an example in which both the transistor 101 and the transistor 102 include a back gate (the gates 223a and 223b in fig. 10), one or both of the transistor 101 and the transistor 102 may not include a back gate.

Although fig. 10 shows an example in which the gate insulating layer 225 is formed only on the channel formation region 231i and does not overlap with the low-resistance region 231n, the gate insulating layer 225 may overlap with at least a part of the low-resistance region 231 n. Fig. 11 shows an example in which the gate insulating layer 225 is in contact with the low-resistance region 231n and the gate insulating layer 211. The gate insulating layer 225 shown in fig. 11 has the following advantages: a process of processing the gate insulating layer 225 using the gate electrode 223 as a mask may be omitted; the step of the formed face of the insulating layer 214 can be reduced; and the like.

When the gate insulating layer 225 is an oxide film having a function of releasing oxygen by heating, the oxygen may be supplied to the low-resistance region 231n by heating, and the carrier density may be decreased and the resistance may be increased. Therefore, the low-resistance region 231n is preferably formed by adding an impurity to a part of the semiconductor layer 231 through the gate insulating layer 225. Thereby, impurities are also added to the gate insulating layer 225. The amount of oxygen released can be reduced by adding impurities to an oxide film having a function of releasing oxygen by heating. Therefore, oxygen can be suppressed from being supplied from the gate insulating layer 225 to the low-resistance region 231n by heating, and the low-resistance state of the low-resistance region 231n can be maintained.

The display device 10 shown in fig. 12 is different from those shown in fig. 10 and 11 in the structures of the transistor 101 and the transistor 102.

The transistor 102 shown in fig. 12 includes a gate electrode 221a, a gate insulating layer 211, a semiconductor layer 231a, a conductive layer 222b, an insulating layer 217, an insulating layer 218, an insulating layer 215, and a gate electrode 223 a. The transistor 101 includes a gate electrode 221b, a gate insulating layer 211, a semiconductor layer 231b, a conductive layer 222c, a conductive layer 222d, an insulating layer 217, an insulating layer 218, an insulating layer 215, and a gate electrode 223 b. Since the structures of the transistor 101 and the transistor 102 in fig. 12 are the same as those of the transistor 102 in fig. 5, detailed description thereof is omitted.

Material of constituent elements

Next, the details of materials and the like that can be used for each constituent element of the display device and the display module according to the present embodiment will be described.

The material and the like of the substrate included in the display device are not particularly limited, and various substrates can be used. For example, a glass substrate, a quartz substrate, a sapphire substrate, a semiconductor substrate, a ceramic substrate, a metal substrate, a plastic substrate, or the like can be used.

By using a substrate having a small thickness, the display device can be reduced in weight and thickness. Further, by using a substrate whose thickness allows it to have flexibility, a display device having flexibility can be realized.

As the liquid crystal material, there are a positive type liquid crystal material in which anisotropy (Δ) of dielectric constant is positive, and a negative type liquid crystal material in which anisotropy is negative. In one embodiment of the present invention, any of positive and negative materials can be used, and a liquid crystal material can be used as appropriate depending on the mode and design used.

In the display device of this embodiment mode, a liquid crystal element using various modes can be used. In addition to the FFS mode, for example, a Liquid Crystal element using an IPS (In-Plane-Switching) mode, a TN (twisted nematic) mode, an ASM (Axially Symmetric Aligned Micro-cell) mode, an OCB (Optically Compensated Birefringence) mode, an FLC (Ferroelectric Liquid Crystal) mode, an AFLC (AntiFerroelectric Liquid Crystal) mode, an ECB (Electrically Compensated Birefringence) mode, a VA-IPS (Vertical Alignment In-Plane-Switching) mode, a guest-host mode, or the like can be used.

The liquid crystal element controls the transmission or non-transmission of light by the optical modulation action of liquid crystal. The optical modulation action of the liquid crystal is controlled by an electric field (horizontal electric field, vertical electric field, or oblique-direction electric field) applied to the liquid crystal. As the Liquid Crystal used for the Liquid Crystal element, a thermotropic Liquid Crystal, a low molecular Liquid Crystal, a Polymer Dispersed Liquid Crystal (PDLC: Polymer Dispersed Liquid Crystal), a ferroelectric Liquid Crystal, an antiferroelectric Liquid Crystal, or the like can be used. These liquid crystal materials exhibit a cholesteric phase, a smectic phase, a cubic phase, a chiral nematic phase, and isotropy, depending on conditions.

As described above, the display device of this embodiment mode can drive the liquid crystal element with a high voltage, and thus can use liquid crystal exhibiting a blue phase. The blue phase is one of liquid crystal phases, and is a phase appearing immediately before a cholesteric phase changes to a homogeneous phase when the temperature of cholesteric liquid crystal is increased. Since the blue phase occurs only in a narrow temperature range, a liquid crystal composition in which 5 wt% or more of a chiral agent is mixed is used for the liquid crystal layer to expand the temperature range. The liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent has a high response speed and is optically isotropic. Further, the liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent does not require an alignment treatment, and viewing angle dependence is small. Further, since the alignment film does not need to be provided and the rubbing treatment is not needed, electrostatic breakdown due to the rubbing treatment can be prevented, and defects and breakage of the display panel in the manufacturing process can be reduced.

Since the display device of the present embodiment is a transmissive liquid crystal display device, a conductive material that transmits visible light is used as both of the pair of electrodes (the pixel electrode 41 and the common electrode 43 a). Further, by forming the conductive layer 46b using a conductive material which transmits visible light, a decrease in the aperture ratio of the pixel can be suppressed even if the capacitor element 104 is provided. As the insulating layer 44 and the insulating layer 45 which are used as dielectrics of the capacitor element, a silicon nitride film is preferably used.

As the conductive material which transmits visible light, for example, a material containing one or more selected from indium (In), zinc (Zn), and tin (Sn) is preferably used. Specifically, indium oxide, Indium Tin Oxide (ITO), indium zinc oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing silicon oxide (ITSO), zinc oxide containing gallium, and the like can be given. In addition, a film containing graphene may also be used. The graphene-containing film may be formed, for example, by reducing a graphene oxide-containing film.

The conductive film which transmits visible light can be formed using an oxide semiconductor (hereinafter also referred to as an oxide conductive layer). The oxide conductive layer preferably contains indium, and more preferably contains In-M-Zn oxide (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf), for example.

The oxide semiconductor is a semiconductor material whose resistance can be controlled by at least one of oxygen defects in the film and impurity concentrations of hydrogen, water, and the like in the film. Thus, by selectively subjecting the oxide semiconductor layer to a treatment in which at least one of oxygen defect and impurity concentration is increased or a treatment in which at least one of oxygen defect and impurity concentration is decreased, the resistivity of the oxide conductive layer can be controlled.

In addition, the oxide conductive layer formed using the oxide semiconductor can be referred to as an oxide semiconductor layer having high carrier density and low resistance, an oxide semiconductor layer having conductivity, or an oxide semiconductor layer having high conductivity.

The transistor included in the display device of this embodiment mode has a structure of either a top gate type or a bottom gate type. Further, gate electrodes may be provided above and below the channel. The semiconductor material used for the transistor is not limited to this, and examples thereof include an oxide semiconductor, silicon, germanium, and the like.

The crystallinity of a semiconductor material used for a transistor is also not particularly limited, and an amorphous semiconductor or a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor in which a part thereof has a crystalline region) can be used. When a crystalline semiconductor is used, deterioration in characteristics of the transistor can be suppressed, and therefore, the crystalline semiconductor is preferable.

For example, a group 14 element, a compound semiconductor, or an oxide semiconductor can be used for the semiconductor layer. Typically, a semiconductor containing silicon, a semiconductor containing gallium arsenide, an oxide semiconductor containing indium, or the like can be used for the semiconductor layer.

An oxide semiconductor is preferably used for a semiconductor in which a channel is formed of a transistor. In particular, an oxide semiconductor having a larger band gap than silicon is preferably used. The use of a semiconductor material having a wider band gap and a lower carrier density than silicon is preferable because it can reduce a current in an off state of a transistor.

By using an oxide semiconductor, a highly reliable transistor in which variations in electrical characteristics are suppressed can be realized.

In addition, since the off-state current is low, the charge stored in the capacitor through the transistor can be held for a long period of time. By using such a transistor for a pixel, the driving circuit can be stopped while the gradation of a displayed image is maintained. As a result, a display device with extremely low power consumption can be realized.

The transistor preferably includes an oxide semiconductor layer which is highly purified and in which formation of oxygen defects is suppressed. This can reduce the off-state current value (off-state current value) of the transistor. Therefore, the holding time of the electrical signal such as the image signal can be extended, and the write interval can be extended in the power-on state. Therefore, the frequency of refresh operation can be reduced, and the effect of suppressing power consumption can be exhibited.

Further, a transistor using an oxide semiconductor can obtain high field-effect mobility, and thus can be driven at high speed. When such a transistor capable of high-speed driving is used for a display device, a transistor for a display portion and a transistor for a driver circuit portion can be formed over the same substrate. That is, since a semiconductor device formed of a silicon wafer or the like does not need to be used separately as a driver circuit, the number of components of the display device can be reduced. Further, a transistor which can be driven at high speed is used also in the display portion, whereby a high-quality image can be provided.

The transistors included in the gate driver GD _ L, GD _ R and the transistors included in the display region 100 may have the same structure or different structures. The transistors included in the gate driver may all have the same structure, or two or more kinds of structures may be combined. Similarly, the transistors included in the display region 100 may have the same structure, or two or more structures may be combined.

As an insulating material that can be used for each insulating layer, a protective layer, and the like included in the display device, an organic insulating material or an inorganic insulating material can be used. Examples of the organic insulating material include acrylic resins, epoxy resins, polyimide resins, polyamide resins, polyimide amide resins, siloxane resins, benzocyclobutene resins, and phenol resins. Examples of the inorganic insulating layer include a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film.

As a conductive layer such as a wiring or an electrode included in the display device, in addition to a gate, a source, and a drain of a transistor, a single-layer structure or a stacked-layer structure of a metal such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten, or an alloy containing these metals as a main component can be used. For example, there may be mentioned: a two-layer structure in which a titanium film is stacked over an aluminum film, a two-layer structure in which a titanium film is stacked over a tungsten film, a two-layer structure in which a copper film is stacked over a molybdenum film, a two-layer structure in which a copper film is stacked over an alloy film containing molybdenum and tungsten, a two-layer structure in which a copper film is stacked over a copper-magnesium-aluminum alloy film, a three-layer structure in which an aluminum film or a copper film is stacked over a titanium film or a titanium nitride film and a titanium film or a titanium nitride film is formed thereover, a three-layer structure in which an aluminum film or a copper film is stacked over a molybdenum film or a molybdenum nitride film and a molybdenum film or a molybdenum nitride film is formed thereover. For example, when the conductive layer has a three-layer structure, it is preferable that a film made of titanium, titanium nitride, molybdenum, tungsten, an alloy containing molybdenum and zirconium, or molybdenum nitride be formed as the first layer and the third layer, and a film made of a low-resistance material such as copper, aluminum, gold, silver, or an alloy of copper and manganese be formed as the second layer. Further, a conductive material having light transmittance such as ITO, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, ITSO, or the like can also be used. In addition, the oxide conductive layer can be formed by controlling the resistivity of the oxide semiconductor.

As the adhesive layer 141, a curable resin such as a thermosetting resin, a photocurable resin, or a two-component type curable resin can be used. For example, acrylic resin, urethane resin, epoxy resin, silicone resin, or the like can be used.

The connecting body 242 may be formed of, for example, an Anisotropic Conductive Film (ACF) or an Anisotropic Conductive Paste (ACP).

The colored layer 39 is a colored layer that transmits light in a predetermined wavelength range. Examples of materials that can be used for the colored layer 39 include metal materials, resin materials, and resin materials containing pigments and dyes.

For example, the light-shielding layer 38 is provided between adjacent colored layers 39 of different colors. For example, a black matrix formed using a metal material or a resin material containing a pigment or a dye may be used as the light shielding layer 38. Further, the light shielding layer 38 is preferably provided in a region other than the display portion such as the driver circuit portion, since light leakage due to waveguide light or the like can be suppressed.

As the backlight unit 30, a direct type backlight, an edge-light type backlight, or the like can be used. As the light source, an led (light Emitting diode), an organic el (electro luminescence) element, or the like can be used.

The thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by sputtering, Chemical Vapor Deposition (CVD), vacuum Deposition, Pulsed Laser Deposition (PLD), Atomic Layer Deposition (ALD), or the like. Examples of the CVD method include a Plasma Enhanced Chemical Vapor Deposition (PECVD) method and a thermal CVD method. As an example of the thermal CVD method, a Metal Organic Chemical Vapor Deposition (MOCVD) method can be given.

The thin films (insulating films, semiconductor films, conductive films, and the like) constituting the display device can be formed by a method such as a spin coating method, a dipping method, a spray coating method, an ink jet printing method, a dispenser method, a screen printing method, an offset printing method, a doctor blade (doctor knife) method, a slit coating method, a roll coating method, a curtain coating method, or a doctor blade coating method.

When a thin film constituting a display device is processed, photolithography or the like can be used. In addition, the island-shaped thin film can be formed by a film formation method using a shadow mask. In addition, the thin film can be processed by a nanoimprint method, a sandblast method, a peeling method, or the like. The following methods are used in photolithography: a method of forming a resist mask on a thin film to be processed, processing the thin film by etching or the like, and removing the resist mask; a method in which a photosensitive film is formed, and then the film is processed into a desired shape by exposure and development.

In the photolithography method, examples of the light used for exposure include i-line (wavelength: 365nm), g-line (wavelength: 436nm), h-line (wavelength: 405nm), and a mixture of these lights. In addition, ultraviolet light, KrF laser, ArF laser, or the like can also be used. Alternatively, exposure may be performed by an immersion exposure technique. Examples of the light used for exposure include Extreme ultraviolet light (EUV) and X-ray. In addition, an electron beam may be used instead of the light for exposure. When extreme ultraviolet light, X-rays, or electron beams are used, extremely fine processing can be performed, and therefore, the method is preferable. In addition, when exposure is performed by scanning with an electron beam or the like, a photomask is not required.

As a method for etching the thin film, a dry etching method, a wet etching method, a sandblasting method, or the like can be used.

[ Metal oxide ]

As a semiconductor layer of a transistor included in the display device of this embodiment mode, a metal oxide which is used as an oxide semiconductor is preferably used. Next, a metal oxide which can be used for the semiconductor layer will be described.

The metal oxide preferably contains at least indium or zinc. Particularly preferably indium and zinc. In addition, aluminum, gallium, yttrium, tin, or the like is preferably contained. Alternatively, one or more of boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, or the like may be contained.

Here, a case where the metal oxide is an In-M-Zn oxide containing indium, an element M, and zinc is considered. Note that the element M is aluminum, gallium, yttrium, tin, or the like. As other elements which can be used as the element M, there are boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium and the like. Note that as the element M, a plurality of the above elements may be combined.

In this specification and the like, a metal oxide containing nitrogen is also sometimes referred to as a metal oxide (metal oxide). In addition, a metal oxide containing nitrogen may also be referred to as a metal oxynitride (metal oxynitride). For example, a metal oxide containing nitrogen such as zinc oxynitride (ZnON) can be used for the semiconductor layer.

In this specification and the like, CAAC (c-axis Aligned crystal) or CAC (Cloud-Aligned Composite) may be mentioned. Note that CAAC is an example of a crystal structure, and CAC is an example of a functional or material structure.

For example, CAC (Cloud-Aligned Composite) -OS can be used as the semiconductor layer.

The CAC-OS or CAC-metal oxide has a function of conductivity in a part of the material, a function of insulation in another part of the material, and a function of a semiconductor as a whole of the material. When CAC-OS or CAC-metal oxide is used for an active layer of a transistor, a function of conductivity is a function of allowing electrons (or holes) used as carriers to flow therethrough, and a function of insulation is a function of preventing electrons used as carriers from flowing therethrough. The CAC-OS or CAC-metal oxide can be provided with a switching function (function of controlling on/off) by the complementary action of the conductive function and the insulating function. By separating the respective functions in the CAC-OS or CAC-metal oxide, the respective functions can be maximized.

The CAC-OS or CAC-metal oxide includes a conductive region and an insulating region. The conductive region has the above-described function of conductivity, and the insulating region has the above-described function of insulation. In addition, in the material, the conductive region and the insulating region are sometimes separated at a nanoparticle level. In addition, the conductive region and the insulating region may be unevenly distributed in the material. In addition, a conductive region having a blurred edge and connected in a cloud shape may be observed.

In the CAC-OS or CAC-metal oxide, the conductive region and the insulating region may be dispersed in the material in a size of 0.5nm or more and 10nm or less, preferably 0.5nm or more and 3nm or less.

Further, CAC-OS or CAC-metaloxide is composed of components having different band gaps. For example, the CAC-OS or CAC-metal oxide is composed of a component having a wide gap due to the insulating region and a component having a narrow gap due to the conductive region. In this configuration, when the carriers are made to flow, the carriers mainly flow in the component having the narrow gap. Further, the component having a narrow gap causes carriers to flow through the component having a wide gap in conjunction with the component having a narrow gap by a complementary action with the component having a wide gap. Therefore, when the above-mentioned CAC-OS or CAC-metal oxide is used for a channel formation region of a transistor, a high current driving force, that is, a large on-state current and a high field-effect mobility can be obtained in an on state of the transistor.

That is, the CAC-OS or CAC-metal oxide may be referred to as a matrix composite or a metal matrix composite.

Oxide semiconductors (metal oxides) are classified into single crystal oxide semiconductors and non-single crystal oxide semiconductors. Examples of the non-single crystal oxide semiconductor include a CAAC-OS (c-oxide aligned crystalline oxide semiconductor), a polycrystalline oxide semiconductor, an nc-OS (nanocrystalline oxide semiconductor), an a-like OS (amorphous oxide semiconductor), and an amorphous oxide semiconductor.

CAAC-OS has c-axis orientation, and a plurality of nanocrystals are connected in the a-b plane direction, and the crystal structure is distorted. Note that the distortion is a portion in which the direction of lattice alignment changes between a region in which lattice alignments coincide and a region in which other lattice alignments coincide among regions in which a plurality of nanocrystals are connected.

Although the nanocrystals are substantially hexagonal, they are not limited to regular hexagonal shapes, and there are cases where they are not regular hexagonal shapes. In addition, the distortion may have a lattice arrangement such as a pentagonal or heptagonal shape. In the CAAC-OS, no clear grain boundary (grain boundary) is observed even in the vicinity of the distortion. That is, it is found that the formation of grain boundaries can be suppressed due to the distortion of the lattice arrangement. This is because CAAC-OS can contain distortion due to low density of oxygen atom arrangement in the a-b plane direction, or due to change in bonding distance between atoms caused by substitution of metal elements.

CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) In which a layer containing indium and oxygen (hereinafter referred to as an In layer) and a layer containing the elements M, zinc, and oxygen (hereinafter referred to as an (M, Zn) layer) are stacked. In addition, indium and the element M may be substituted for each other, and In the case where the element M In the (M, Zn) layer is substituted with indium, the layer may be represented as an (In, M, Zn) layer. In addition, In the case where indium In the In layer is replaced with the element M, the layer may be represented as an (In, M) layer.

CAAC-OS is a metal oxide with high crystallinity. On the other hand, in CAAC-OS, it is not easy to observe a clear grain boundary, and therefore, a decrease in electron mobility due to the grain boundary does not easily occur. In addition, the crystallinity of the metal oxide may be lowered by the entry of impurities, the generation of defects, or the like, and thus the CAAC-OS may be said to be impurities or defects (oxygen vacancies (also referred to as V)_O(oxygen vaccy)), etc.). Therefore, the metal oxide including CAAC-OS is stable in physical properties. Therefore, the metal oxide including the CAAC-OS has high heat resistance and high reliability.

In nc-OS, the atomic arrangement in a minute region (for example, a region of 1nm to 10nm, particularly 1nm to 3 nm) has periodicity. In addition, no regularity in crystallographic orientation was observed between different nanocrystals for nc-OS. Therefore, orientation was not observed in the entire film. Therefore, sometimes nc-OS is not different from a-likeOS or an amorphous oxide semiconductor in some analysis methods.

In addition, indium-gallium-zinc oxide (hereinafter, IGZO), which is one of metal oxides including indium, gallium, and zinc, may have a stable structure when composed of the above-described nanocrystal. In particular, IGZO tends to be less likely to undergo crystal growth in the atmosphere, and therefore, it is sometimes structurally stable when IGZO is formed of small crystals (for example, the nanocrystals described above) as compared with when IGZO is formed of large crystals (here, crystals of several mm or crystals of several cm).

The a-like OS is a metal oxide having a structure between nc-OS and an amorphous oxide semiconductor. The a-like OS contains holes or low density regions. That is, the crystallinity of a-like OS is lower than that of nc-OS and CAAC-OS.

Oxide semiconductors (metal oxides) have various structures and various characteristics. The oxide semiconductor according to one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, nc-OS, and CAAC-OS.

The metal oxide film used as the semiconductor layer may be formed using either or both of an inert gas and an oxygen gas. Note that the oxygen flow rate ratio (oxygen partial pressure) when forming the metal oxide film is not particularly limited. However, in the case of obtaining a transistor with high field-effect mobility, the oxygen flow rate ratio (oxygen partial pressure) in forming the metal oxide film is preferably 0% or more and 30% or less, more preferably 5% or more and 30% or less, and further preferably 7% or more and 15% or less.

The energy gap of the metal oxide is preferably 2eV or more, more preferably 2.5eV or more, and further preferably 3eV or more. Thus, by using a metal oxide having a wide energy gap, the off-state current of the transistor can be reduced.

The metal oxide film may be formed by a sputtering method. In addition, PLD method, PECVD method, thermal CVD method, ALD method, vacuum deposition method, or the like can be used.

As described above, in the display device according to one embodiment of the present invention, the pixel includes two capacitor elements which transmit visible light and overlap each other, and thus the pixel can achieve both a high aperture ratio and a large holding capacitance.

Further, since the display device according to one embodiment of the present invention has a function of adding a correction signal to an image signal, the liquid crystal element can be driven at a voltage higher than the output voltage of the source driver.

This embodiment mode can be combined with other embodiment modes as appropriate. In the present specification, when a plurality of configuration examples are shown in one embodiment, the configuration examples may be appropriately combined.

(embodiment mode 2)

In this embodiment, a display device according to an embodiment of the present invention will be described with reference to fig. 13 to 24. The display device described in this embodiment mode can also be said to be a modified example of the display device described in embodiment mode 1. Therefore, detailed description of the portions described in embodiment 1 may be omitted.

Structural example of display device 3

A configuration example of a display device in which a connection portion between a transistor and a pixel electrode has a function of transmitting visible light will be described with reference to fig. 13 to 16. When the connecting portion has a function of transmitting visible light, the connecting portion may be provided in an opening portion (a portion for display) of a pixel. This can increase the aperture ratio of the pixel and increase the transmittance of the pixel. By increasing the transmittance of the pixel, the luminance of the backlight unit can be reduced. Therefore, power consumption of the display device can be reduced. In addition, the resolution of the display device can be improved.

Overlook layout of pixels

Fig. 13A to 13C show top views of the pixels. The pixel shown in fig. 13A to 13C is a modified example of the pixel shown in fig. 4A to 4C. Fig. 13A is a plan view of the stacked structure of the gate electrode 221 to the common electrode 43A as viewed from the common electrode 43A side. Fig. 13B is a plan view when the common electrode 43A is removed from the stacked structure of fig. 13A, and fig. 13C is a plan view when the common electrode 43A and the pixel electrode 41 are removed from the stacked structure of fig. 13A.

The pixel includes a connection portion 71 and a connection portion 72. In the connection portion 71, the pixel electrode 41 is electrically connected to the transistor 102. Specifically, the conductive layer 222f serving as a source or a drain of the transistor 102 is in contact with the conductive layer 46b, and the conductive layer 46b is in contact with the pixel electrode 41. The conductive layer 222f, the conductive layer 222g, the conductive layer 46b, and the pixel electrode 41, which function as the source and the drain of the transistor 102, each have a function of transmitting visible light. That is, the connection portion 71 shown in fig. 13A has a function of transmitting visible light. Further, the conductive layer 46b need not be provided, and the conductive layer 222f may be in contact with the pixel electrode 41. In the connection portion 72, the conductive layer 46a is electrically connected to the common electrode 43 a. Specifically, the conductive layer 46a is in contact with the common electrode 43 a.

In this manner, by using a conductive material which transmits visible light as the conductive layer 222f which is used as the source or the drain of the transistor 102, the connection portion 71 can be used as a region which transmits visible light, and thus the aperture ratio of the pixel can be increased. Therefore, power consumption of the display device can be reduced.

As shown in fig. 13B and the like, the conductive layer 222B serving as a signal line is electrically connected to the semiconductor layer 231 through the conductive layer 222 g. In addition, the conductive layer 222g may not be provided, and the conductive layer 222b may be in contact with the semiconductor layer 231.

As for a conductive material which transmits visible light and can be used for the conductive layer 222f and the conductive layer 222g which are used as a source and a drain of the transistor 102, embodiment 1 can be referred to. The conductive material that transmits visible light may have a higher resistivity than a conductive material such as copper or aluminum that blocks visible light. In order to prevent signal delay, the bus lines such as the scan lines and the signal lines are preferably formed using a conductive material (metal material) having low resistivity. However, a conductive material that transmits visible light may be used for the bus lines depending on the size of the pixels, the width of the bus lines, the thickness of the bus lines, and the like.

Specifically, the conductive layer 222b used as a signal line is preferably formed using a conductive material having low resistivity. Since the gate electrode 221 is also a conductive layer used as a scanning line, it is preferably formed using a conductive material having low resistivity. Examples of the conductive material having low resistivity include metals and alloys. The conductive layer 222b and the gate electrode 221 may also be formed using a conductive material that blocks visible light.

Further, by using a conductive layer which shields visible light for the gate electrode 221, light of a backlight can be suppressed from being irradiated to the channel formation region of the semiconductor layer 231. In this manner, when the channel formation region of the semiconductor layer overlaps with the conductive layer which blocks visible light, variation in characteristics of the transistor due to light can be suppressed. This can improve the reliability of the transistor.

The common electrode 43A shown in fig. 13A has a top surface shape provided with a plurality of slits. Fig. 4A shows an example in which a slit is provided substantially parallel to the conductive layer 222b used as a signal line, but as shown in fig. 13A, a slit may be provided so as to be inclined with respect to the conductive layer 222 b. The shapes of the common electrode 43a and the pixel electrode 41 (presence or absence of slits, the number of slits, the size, the shape, and the like) can be appropriately set according to the pixel layout. In order to increase the aperture ratio of the pixel, it is preferable to use as large an area as possible of the connection portion 71, the connection portion 72, and the vicinity thereof as the display area.

Cross-sectional Structure of display Module

Fig. 14 shows a cross-sectional view of a display module. The display module shown in fig. 14 is a modification of the display module shown in fig. 5. As for a detailed description of the same configuration as that of the display module shown in fig. 5 in the display module shown in fig. 14, embodiment 1 can be referred to. The cross-sectional structure of the pixel in fig. 14 corresponds to a cross-sectional view between the chain line C1-C2 shown in fig. 13A.

The display module shown in fig. 14 includes the display device 10, the polarizing plate 61, the polarizing plate 63, the backlight unit 30, the FPC172, and the like.

Since the display device 10 includes the colored layer 39, a color image can be displayed. Light outside a specified wavelength region of the light 35 emitted from the light source included in the backlight unit 30 is absorbed by the colored layer 39. Thus, for example, light emitted from a red pixel (sub-pixel) to the outside of the display module appears red, light emitted from a green pixel (sub-pixel) to the outside of the display module appears green, and light emitted from a blue pixel (sub-pixel) to the outside of the display module appears blue.

The display device 10 includes a substrate 31, a substrate 32, a transistor 102, a conductive layer 222b, a conductive layer 46a, a conductive layer 46b, a conductive layer 46c, an insulating layer 44, an insulating layer 45, a pixel electrode 41, a liquid crystal layer 42, a common electrode 43a, a conductive layer 43b, a conductive layer 222e, an alignment film 133a, an alignment film 133b, an adhesive layer 141, a protective layer 135, a light-shielding layer 38, a coloring layer 39, and the like.

Transistor 102 is located on substrate 31. The transistor 102 includes a gate electrode 221, a gate insulating layer 211, a semiconductor layer 231, a conductive layer 222f, a conductive layer 222g, an insulating layer 217, an insulating layer 218, an insulating layer 215, and a gate electrode 223. One of the conductive layer 222f and the conductive layer 222g is used as a source electrode, and the other is used as a drain electrode. The insulating layer 217, the insulating layer 218, and the insulating layer 215 are used as a gate insulating layer. A detailed description of the same portion of the transistor 102 in fig. 14 as the transistor 102 in fig. 5 is omitted.

The conductive layer 222f and the conductive layer 222g are formed using a material that transmits visible light. Thus, the light 35 shown in fig. 14 is transmitted through the connection portion between the conductive layer 46b and the conductive layer 222f and is emitted to the outside of the display module. Thus, the aperture ratio of the pixel can be increased, and the power consumption of the display device can be reduced. The conductive layer 222g is electrically connected to the conductive layer 222b serving as a signal line.

The FPC172 is electrically connected to the conductive layer 222 e. The conductive layer 222e can be formed using the same process and material as the conductive layer 222 b.

In each configuration example of the display device shown in this embodiment mode, the conductive layer 46a, the insulating layer 44, and the pixel electrode 41 can be used as one capacitor element 104. Further, the pixel electrode 41, the insulating layer 45, and the common electrode 43a can be used as one capacitor element 105. As such, the display device 10 includes two capacitance elements in one pixel. Therefore, the holding capacitance of the pixel can be increased. In addition, both the two capacitor elements are formed using a material that transmits visible light, and have regions that overlap each other. Thus, the pixel can achieve both a high aperture ratio and a large holding capacitance.

Similarly, a structure in which a connection portion electrically connecting a transistor and a pixel electrode included in the display module shown in fig. 6 or 7 has a function of transmitting visible light may be employed.

Overlook layout of pixels

Fig. 15A to 15C show top views of the pixels. The pixel shown in fig. 15A to 15C is a modified example of the pixel shown in fig. 9A to 9C. Fig. 15A is a plan view of the stacked structure of the gate electrode 221a and the gate electrode 221b to the common electrode 43a when viewed from the common electrode 43a side. Fig. 15B is a plan view when the common electrode 43a is removed from the stacked structure of fig. 15A, and fig. 15C is a plan view when the common electrode 43a and the pixel electrode 41 are removed from the stacked structure of fig. 15A.

The pixel includes a connection portion 73 and a connection portion 74. In the connection portion 73, the pixel electrode 41 is electrically connected to the transistor 102. Specifically, the low-resistance region included in the semiconductor layer 231a of the transistor 102 is in contact with the conductive layer 46b, and the conductive layer 46b is in contact with the pixel electrode 41. The semiconductor layer 231a, the conductive layer 46b, and the pixel electrode 41 all have a function of transmitting visible light. That is, the connection portion 73 shown in fig. 15A has a function of transmitting visible light. In the connection portion 74, the conductive layer 46a is electrically connected to the transistor 101. Specifically, the low-resistance region included in the semiconductor layer 231b of the transistor 101 is in contact with the conductive layer 46 a. The conductive layer 46a and the semiconductor layer 231b both have a function of transmitting visible light. As shown in fig. 15A, the connection portion 74 may have a function of transmitting visible light.

By using a material which transmits visible light as a semiconductor layer of a transistor and electrically connecting a low-resistance region of the semiconductor layer to a pixel electrode which transmits visible light (the low-resistance region and the pixel electrode may be electrically connected by a conductive layer which transmits visible light), the connection portion 73 (and the connection portion 74) can be used as a region which transmits visible light, and thus the aperture ratio of a pixel can be increased. Therefore, power consumption of the display device can be reduced.

As a material for transmitting visible light used for a semiconductor layer of a transistor, a metal oxide is preferably used. For details of the metal oxide, embodiment 1 can be referred to.

Cross-sectional Structure of display Module

Fig. 16A shows a cross-sectional view of a display module. The display module shown in fig. 16A is a modification of the display module shown in fig. 10. As for a detailed description of the same configuration as that of the display module shown in fig. 10 in the display module shown in fig. 16A, embodiment 1 can be referred to. The cross-sectional structure of the pixel in fig. 16A corresponds to a cross-sectional view between the dashed-dotted lines D1-D2 shown in fig. 15A.

The display module shown in fig. 16A includes the display device 10, the polarizing plate 61, the polarizing plate 63, the backlight unit 30, the FPC172, and the like.

Transistor 101 and transistor 102 are located over substrate 31. The transistor 102 includes a gate electrode 221a, a gate insulating layer 211, a semiconductor layer 231a, a conductive layer 222b, an insulating layer 212, an insulating layer 213, a gate insulating layer 225a, and a gate electrode 223 a. The transistor 101 includes a gate electrode 221b, a gate insulating layer 211, a semiconductor layer 231b, a conductive layer 222d, an insulating layer 212, an insulating layer 213, a gate insulating layer 225b, and a gate electrode 223 b. The same portions as the transistor 102 in fig. 7 in the transistors 101 and 102 in fig. 16A are not described in detail.

The conductive layer 46b is located on the insulating layer 215, the insulating layer 44 is located on the conductive layer 46b, and the pixel electrode 41 is located on the insulating layer 44. The pixel electrode 41 is electrically connected to one of the low-resistance regions 231n of the semiconductor layer 231 a. Specifically, one of the low-resistance regions 231n of the semiconductor layer 231a is connected to the conductive layer 46b, and the conductive layer 46b is connected to the pixel electrode 41. The other of the low-resistance regions 231n of the semiconductor layer 231a is electrically connected to the conductive layer 222b serving as a signal line.

The light 35 shown in fig. 16A is transmitted through the connecting portion between the conductive layer 46b and the low-resistance region 231n and is emitted to the outside of the display module. Thus, the aperture ratio of the pixel can be increased, and the power consumption of the display device can be reduced.

The conductive layer 46a is located on the insulating layer 215. In fig. 16A, the conductive layer 46A is electrically connected to one of the low-resistance regions 231n of the semiconductor layer 231 b. Specifically, the conductive layer 46a is in contact with one of the low-resistance regions 231n of the semiconductor layer 231b through openings provided in the insulating layer 212, the insulating layer 213, the insulating layer 214, and the insulating layer 215. The other of the low-resistance regions 231n of the semiconductor layer 231b is electrically connected to the conductive layer 222d serving as a signal line.

The light 35 shown in fig. 16A is emitted to the outside of the display module through the connecting portion between the conductive layer 46A and the low-resistance region 231 n. This can further increase the aperture ratio of the pixel, and can further reduce the power consumption of the display device.

As in the connection portion between the semiconductor layer 231B and the conductive layer 46a (corresponding to the connection portion 74 in fig. 15A) shown in fig. 16B, the pixel may include a connection portion overlapping the light-shielding layer 38. That is, in the case where the pixel included in the display device according to one embodiment of the present invention includes the first connection portion and the second connection portion, the display device may be configured to emit the light 35 to the outside of the display module through the first connection portion and not to emit the light 35 to the outside of the display module through the second connection portion. As shown in fig. 10, the conductive layer 46a may be in contact with the conductive layer 222c through openings provided in the insulating layer 214 and the insulating layer 215.

The FPC172 is electrically connected to the conductive layer 222 e. The conductive layer 222e can be formed using the same process and material as the conductive layers 222b and 222 d.

Similarly, a structure in which a connection portion electrically connecting a transistor and a pixel electrode included in the display module shown in fig. 11 or 12 has a function of transmitting visible light may be employed.

Structural example of display device 4

A configuration example of a display device having a function of displaying by a field sequential driving method will be described with reference to fig. 17 to 20. The field sequential driving method is a driving method for performing color display by time division. Specifically, light-emitting elements of red, green, blue, and other colors are sequentially caused to emit light with time shifts, and pixels are driven in synchronization with the light-emitting elements, thereby performing color display by a sequential additive color mixing method.

When the field sequential driving method is adopted, it is not necessary to form one pixel by a plurality of sub-pixels of different colors, and thus the aperture ratio of the pixel can be improved. In addition, the resolution of the display device can be improved. Further, since it is not necessary to provide a coloring layer such as a color filter, light absorption by the coloring layer is eliminated, and the transmittance of the pixel can be improved. Therefore, a desired luminance can be obtained with low power consumption, and power consumption can be reduced. In addition, the manufacturing process of the display device can be simplified and the manufacturing cost can be reduced.

When the field sequential driving method is adopted, a high frame rate is required. A display device according to one embodiment of the present invention includes two capacitor elements in one pixel, and since a holding capacitance of the pixel is large and a high voltage can be supplied to a liquid crystal element, the response speed of the liquid crystal element can be increased. For example, by employing overdrive in which the orientation of liquid crystal is changed rapidly by temporarily setting the voltage applied to the liquid crystal element to a high level, the response speed of the liquid crystal element can be improved. Therefore, the display device according to one embodiment of the present invention can be said to be configured suitably when a field sequential driving method requiring a high frame rate is employed.

When the rotational viscosity coefficient of the liquid crystal material is small, the response speed of the liquid crystal element is improved, and therefore, it is preferable. Specifically, the rotational viscosity coefficient of the liquid crystal material is preferably 10mPa · sec or more and 150mPa · sec or less.

In addition, in the case of performing the FFS mode used in the display device of the present embodiment, it is preferable to use a positive liquid crystal material because the response speed of liquid crystal can be increased compared to the case of using a negative liquid crystal material. When a positive type liquid crystal material is used, the rubbing angle of the alignment film (the angle between the long side of the slit and the rubbing direction) is preferably 15 ° or more and 45 ° or less. When the rubbing angle is large, the response speed of the liquid crystal can be improved, but the driving voltage may be increased. Since the display device according to one embodiment of the present invention can supply a high voltage to the liquid crystal element, high display quality can be achieved even if the rubbing angle is increased.

In addition, in the case of using a negative-type liquid crystal material, the rubbing angle of the alignment film is preferably 45 ° or more and 75 ° or less.

Further, the smaller the thickness (cell gap) of the liquid crystal layer, the higher the response speed of the liquid crystal can be, and therefore, this is preferable. For example, when the field sequential driving method is adopted, the cell gap is preferably 1 μm or more and 2.5 μm or less. For example, the minimum value of the thickness of the liquid crystal layer in one pixel is preferably 1 μm or more and 2.5 μm or less. Alternatively, the height of the member (also referred to as a spacer) having a function of adjusting the cell gap is preferably 1 μm or more and 2.5 μm or less.

Further, a liquid crystal exhibiting a blue phase is preferable because it has a high response speed. The display device of the present embodiment can be said to have a structure suitable for a case where liquid crystal exhibiting a blue phase is used by driving a liquid crystal element with a high voltage.

Overlook layout of pixels

Fig. 17A to 17C show top views of pixels. The pixel shown in fig. 17A to 17C is a modified example of the pixel shown in fig. 4A to 4C. Fig. 17A is a plan view of the stacked structure of the gate electrode 221 to the common electrode 43a as viewed from the common electrode 43a side. Fig. 17B is a plan view when the common electrode 43a is removed from the stacked structure of fig. 17A, and fig. 17C is a plan view when the common electrode 43a and the pixel electrode 41 are removed from the stacked structure of fig. 17A.

Like the pixel shown in fig. 4A to 4C, the pixel shown in fig. 17A to 17C includes a connection portion 71, a connection portion 72, a transistor 102, a pixel electrode 41, a common electrode 43a, a conductive layer 46a, and the like. The pixel shown in fig. 4A to 4C corresponds to one of a plurality of sub-pixels included in the pixel. On the other hand, the pixel shown in fig. 17A to 17C corresponds to one pixel including no sub-pixel. Therefore, the aperture ratio of the pixel can be improved.

Cross-sectional Structure of display Module

Fig. 18 shows a cross-sectional view of a display module. The display module shown in fig. 18 is a modification of the display module shown in fig. 5. As for a detailed description of the same configuration as that of the display module shown in fig. 5 in the display module shown in fig. 18, embodiment 1 can be referred to. The cross-sectional structure of the pixel in fig. 18 corresponds to the cross-sectional views between the dashed dotted lines E1-E2 and between the dashed dotted lines E3-E4 shown in fig. 17A.

The display module shown in fig. 18 includes the display device 10, the polarizing plate 61, the polarizing plate 63, the backlight unit 30, the FPC172, and the like.

The display device 10 shown in fig. 18 can display a color image by a field sequential driving method. Therefore, the display device 10 shown in fig. 18 does not include a coloring layer such as a color filter. This can improve the transmittance of the pixel.

As the backlight unit 30, for example, Light Emitting Diodes (LEDs) of three colors of red, green, and blue can be used.

Transistor 102 is located on substrate 31. The structure of the transistor 102 is the same as that of fig. 5.

A light-shielding layer 38 is provided on the substrate 32, and a protective layer 135 covering the light-shielding layer 38 is provided. The alignment film 133b is provided in contact with the protective layer 135. Further, an alignment film 133a is provided on the common electrode 43 a. The liquid crystal layer 42 is interposed between the alignment film 133a and the alignment film 133 b. The protective layer 135 can suppress diffusion of impurities contained in the light-shielding layer 38 and the like into the liquid crystal layer 42.

Similarly, the display device included in the display module shown in fig. 6 or 7 may have a function of displaying by a field sequential driving method.

Overlook layout of pixels

Fig. 19A to 19C show top views of the pixels. The pixel shown in fig. 19A to 19C is a modified example of the pixel shown in fig. 9A to 9C. Fig. 19A is a plan view of the stacked structure of the gate electrode 221a and the gate electrode 221b to the common electrode 43a when viewed from the common electrode 43a side. Fig. 19B is a plan view when the common electrode 43a is removed from the stacked structure of fig. 19A, and fig. 19C is a plan view when the common electrode 43a and the pixel electrode 41 are removed from the stacked structure of fig. 19A.

The pixel shown in fig. 19A to 19C includes a connection portion 73, a connection portion 74, a transistor 101, a transistor 102, a pixel electrode 41, a common electrode 43a, a conductive layer 46a, and the like, as in the pixel shown in fig. 9A to 9C. The pixel shown in fig. 9A to 9C corresponds to one of a plurality of sub-pixels included in the pixel. On the other hand, the pixel shown in fig. 19A to 19C corresponds to one pixel including no sub-pixel. Therefore, the aperture ratio of the pixel can be improved.

Cross-sectional Structure of display Module

Fig. 20 shows a cross-sectional view of a display module. The display module shown in fig. 20 is a modification of the display module shown in fig. 10. As for a detailed description of the same configuration as that of the display module shown in fig. 10 in the display module shown in fig. 20, embodiment 1 can be referred to. The cross-sectional structure of the pixel in fig. 20 corresponds to the cross-sectional views between the dashed dotted lines F1-F2 and between the dashed dotted lines F3-F4 shown in fig. 19A.

The display module shown in fig. 20 includes the display device 10, the polarizing plate 61, the polarizing plate 63, the backlight unit 30, the FPC172, and the like.

The display device 10 shown in fig. 20 can display a color image by a field sequential driving method. Therefore, the display device 10 shown in fig. 20 does not include a coloring layer such as a color filter. This can improve the transmittance of the pixel.

Transistor 101 and transistor 102 are located over substrate 31. The structures of the transistor 101 and the transistor 102 are the same as those of fig. 10.

Similarly, the display device included in the display module shown in fig. 11 or 12 may have a function of displaying by a field sequential driving method.

Example of Structure of display device 5

With reference to fig. 21 to 24, description will be given of a configuration example of a display device which has a function of performing display by a field sequential driving method and a function of transmitting visible light through a connection portion where a transistor is electrically connected to a pixel electrode.

As described above, when the field sequential driving method is adopted, the aperture ratio of the pixel and the transmittance of the pixel can be increased. In addition, when the connection portion where the transistor is electrically connected to the pixel electrode has a structure that transmits visible light, the aperture ratio of the pixel and the transmittance of the pixel can be further increased.

Note that, as for the detailed description of the same structure as the above-described drawings among the structures shown in fig. 21 to 24, the above description may be referred to.

Overlook layout of pixels

Fig. 21A to 21C show top views of pixels. The pixel shown in fig. 21A to 21C is a modified example of the pixel shown in fig. 17A to 17C. Fig. 21A is a plan view of the stacked structure of the gate electrode 221 to the common electrode 43a as viewed from the common electrode 43a side. Fig. 21B is a plan view when the common electrode 43a is removed from the stacked structure of fig. 21A, and fig. 21C is a plan view when the common electrode 43a and the pixel electrode 41 are removed from the stacked structure of fig. 21A.

The pixel includes a connection portion 71 and a connection portion 72. In the connection portion 71, the pixel electrode 41 is electrically connected to the transistor 102. Specifically, the conductive layer 222f serving as a source or a drain of the transistor 102 is in contact with the conductive layer 46b, and the conductive layer 46b is in contact with the pixel electrode 41. The conductive layer 222f, the conductive layer 46b, and the pixel electrode 41 all have a function of transmitting visible light. That is, the connection portion 71 shown in fig. 21A has a function of transmitting visible light. Further, the conductive layer 46b need not be provided, and the conductive layer 222f may be in contact with the pixel electrode 41. In the connection portion 72, the conductive layer 46a is electrically connected to the common electrode 43 a. Specifically, the conductive layer 46a is in contact with the common electrode 43 a.

By using a conductive material which transmits visible light as the conductive layer 222f which is used as a source or a drain of the transistor 102, the connection portion 71 can be used as a region which transmits visible light, and thus the aperture ratio of a pixel can be increased. Therefore, power consumption of the display device can be reduced.

Although fig. 17A to 17C show an example in which the connection portion 71 of the pixel electrode 41 and most of the area other than the vicinity thereof overlap the conductive layer 46a, fig. 21A to 21C show an example in which only a part of the area of the pixel electrode 41 overlaps the conductive layer 46 a. The plan view layout of the conductive layer 46a can be appropriately set according to the holding capacity of the capacitor element 104. For example, the conductive layer 46a may have a slit. Similarly, the planar layout of the pixel electrode 41 can be appropriately set according to the holding capacities of the capacitor element 104 and the capacitor element 105. For example, the pixel electrode 41 may have a slit.

Cross-sectional Structure of display Module

Fig. 22 shows a cross-sectional view of a display module. The cross-sectional structure of the pixel in fig. 22 corresponds to the cross-sectional views between the dot-dash lines G1-G2 and between the dot-dash lines G3-G4 shown in fig. 21A.

The display module shown in fig. 22 includes the display device 10, the polarizing plate 61, the polarizing plate 63, the backlight unit 30, the FPC172, and the like.

The display device 10 shown in fig. 22 can display a color image by using a field sequential driving method. Therefore, the display device 10 shown in fig. 22 does not include a coloring layer such as a color filter. This can improve the transmittance of the pixel.

Transistor 102 is located on substrate 31. The structure of the transistor 102 is the same as that of fig. 14.

The conductive layer 222f and the conductive layer 222g are formed using a material that transmits visible light. Thus, the light 35 shown in fig. 22 is transmitted through the connection portion between the conductive layer 46b and the conductive layer 222f and is emitted to the outside of the display module. Thus, the aperture ratio of the pixel can be increased, and the power consumption of the display device can be reduced. The conductive layer 222g is electrically connected to the conductive layer 222b serving as a signal line.

The FPC172 is electrically connected to the conductive layer 222 e. The conductive layer 222e can be formed using the same process and material as the conductive layer 222 b.

Overlook layout of pixels

Fig. 23A to 23C show top views of pixels. The pixel shown in fig. 23A to 23C is a modified example of the pixel shown in fig. 19A to 19C. Fig. 23A is a plan view of the stacked structure of the gate electrode 221a and the gate electrode 221b to the common electrode 43A when viewed from the common electrode 43A side. Fig. 23B is a plan view when the common electrode 43A is removed from the stacked structure of fig. 23A, and fig. 23C is a plan view when the common electrode 43A and the pixel electrode 41 are removed from the stacked structure of fig. 23A.

The pixel includes a connection portion 73 and a connection portion 74. In the connection portion 73, the pixel electrode 41 is electrically connected to the transistor 102. Specifically, the low-resistance region included in the semiconductor layer 231a of the transistor 102 is in contact with the conductive layer 46b, and the conductive layer 46b is in contact with the pixel electrode 41. The semiconductor layer 231a, the conductive layer 46b, and the pixel electrode 41 all have a function of transmitting visible light. That is, the connecting portion 73 shown in fig. 23A has a function of transmitting visible light. In the connection portion 74, the conductive layer 46a is electrically connected to the transistor 101. Specifically, the low-resistance region included in the semiconductor layer 231b of the transistor 101 is in contact with the conductive layer 46 a. The conductive layer 46a and the semiconductor layer 231b both have a function of transmitting visible light. As shown in fig. 23A, the connection portion 74 may have a function of transmitting visible light.

As a material for transmitting visible light used for a semiconductor layer of a transistor, a metal oxide is preferably used. For details of the metal oxide, embodiment 1 can be referred to.

Cross-sectional Structure of display Module

Fig. 24 shows a cross-sectional view of a display module. The cross-sectional structure of the pixel in fig. 24 corresponds to the cross-sectional views between the dot-dash lines H1-H2 and between the dot-dash lines H3-H4 shown in fig. 23A.

The display module shown in fig. 24 includes the display device 10, the polarizing plate 61, the polarizing plate 63, the backlight unit 30, the FPC172, and the like.

The display device 10 shown in fig. 24 can display a color image by a field sequential driving method. Therefore, the display device 10 shown in fig. 24 does not include a coloring layer such as a color filter. This can improve the transmittance of the pixel.

Transistor 101 and transistor 102 are located over substrate 31. The structures of the transistor 101 and the transistor 102 are the same as those of fig. 16A.

The light 35 shown in fig. 24 is transmitted through the connecting portion between the conductive layer 46b and the low-resistance region 231n and is emitted to the outside of the display module. Thus, the aperture ratio of the pixel can be increased, and the power consumption of the display device can be reduced.

The FPC172 is electrically connected to the conductive layer 222 e. The conductive layer 222e can be formed using the same process and material as the conductive layers 222b and 222 d.

In addition, in the display device according to one embodiment of the present invention, since the connection portion between the transistor and the pixel electrode has a function of transmitting visible light, the aperture ratio of the pixel can be further increased.

Further, since the display device according to one embodiment of the present invention has a function of performing display by a field sequential driving method, the aperture ratio of the pixel can be further increased, and the transmittance of the pixel can be increased because a coloring layer such as a color filter is not required.

This embodiment mode can be combined with other embodiment modes as appropriate.

(embodiment mode 3)

In this embodiment, an electronic device according to an embodiment of the present invention will be described with reference to fig. 25 and 26.

The electronic device of the present embodiment includes a display unit having the display device of one embodiment of the present invention. Thus, the display unit of the electronic device can display a high-quality image. Further, display can be performed with high reliability in a wide temperature range.

The display unit of the electronic device according to the present embodiment can display, for example, an image having a resolution of full high definition, 2K, 4K, 8K, 16K, or higher. The screen size of the display unit may be 20 inches or more, 30 inches or more, 50 inches or more, 60 inches or more, or 70 inches or more in diagonal.

Examples of electronic devices that can use the display device according to one embodiment of the present invention include electronic devices having a large screen, such as a television set, a desktop or notebook personal computer, a display for a computer or the like, a large-sized game machine such as a Digital Signage (Digital signal) or a pachinko machine, and further include a Digital camera, a Digital video camera, a Digital photo frame, a mobile phone, a portable game machine, a portable information terminal, and an audio reproducing device. The display device according to one embodiment of the present invention can be suitably used for a portable electronic device, a wearable electronic device, a VR (virtual Reality) device, an AR (Augmented Reality) device, and the like.

The electronic device according to one embodiment of the present invention may include a secondary battery, and the secondary battery is preferably charged by non-contact power transmission.

Examples of the secondary battery include lithium ion secondary batteries such as lithium polymer batteries (lithium ion polymer batteries) using a gel electrolyte, nickel hydrogen batteries, nickel cadmium batteries, organic radical batteries, lead storage batteries, air secondary batteries, nickel zinc batteries, and silver zinc batteries.

The electronic device according to one embodiment of the present invention may include an antenna. By receiving the signal through the antenna, an image, data, or the like can be displayed on the display unit. In addition, when the electronic device includes an antenna and a secondary battery, the antenna may be used for non-contact power transmission.

The electronic device according to one embodiment of the present invention may further include a sensor (the sensor has a function of measuring a force, a displacement, a position, a velocity, an acceleration, an angular velocity, a rotational speed, a distance, light, liquid, magnetism, a temperature, a chemical substance, sound, time, hardness, an electric field, current, voltage, electric power, radiation, a flow rate, humidity, inclination, vibration, odor, or infrared).

An electronic device according to one embodiment of the present invention can have various functions. For example, the following functions may be provided: a function of displaying various information (still image, moving image, character image, and the like) on the display unit; a function of a touch panel; a function of displaying a calendar, date, time, or the like; functions of executing various software (programs); a function of performing wireless communication; a function of reading out a program or data stored in a storage medium; and the like.

Further, an electronic apparatus including a plurality of display portions may have a function of mainly displaying image data on one display portion and mainly displaying text information on another display portion, a function of displaying a three-dimensional image by displaying an image in consideration of parallax on a plurality of display portions, or the like. Also, the electronic apparatus having the image receiving section may have the following functions: shooting a static image; shooting a dynamic image; automatically or manually correcting the shot image; storing the photographed image in a recording medium (external or built-in the electronic apparatus); displaying the photographed image on a display section; and the like. The functions of the electronic device according to one embodiment of the present invention are not limited to these, and the electronic device may have various functions.

Fig. 25A shows a television apparatus 1810. The television device 1810 includes a display portion 1811, a housing 1812, a speaker 1813, and the like. The television device 1810 may further include an LED lamp, operation keys (including a power switch or an operation switch), connection terminals, various sensors, a microphone, and the like.

The television apparatus 1810 may be operated by a remote controller 1814.

As broadcast waves that can be received by the television device 1810, there are ground waves, radio waves transmitted from a satellite, and the like. The broadcast waves include analog broadcasts, digital broadcasts, and the like, and also include video and audio broadcasts, audio-only broadcasts, and the like. For example, a broadcast wave transmitted in a specified frequency band of a UHF band (about 300MHz to 3GHz) or a VHF band (30MHz to 300MHz) can be received. For example, by using a plurality of data received in a plurality of frequency bands, the transmission rate can be increased, so that more information can be obtained. Accordingly, a video having a resolution higher than full high definition can be displayed on the display portion 1811. For example, images having a resolution of 4K, 8K, 16K, or higher may be displayed.

Further, the following structure may be adopted: the image displayed on the display portion 1811 is generated using broadcast data transmitted by a data transmission technique through a computer Network such as the internet, a Local Area Network (LAN), or Wi-Fi (registered trademark). In this case, the television apparatus 1810 may not include a tuner.

FIG. 25B shows the digital signage 1820 disposed on the cylindrical post 1822. The digital signage 1820 has a display portion 1821.

The larger the display section 1821 is, the larger the amount of information that can be provided by the display device at one time. The larger the display portion 1821, the more attractive the attention, and the advertising effect can be improved.

The use of a touch panel for the display portion 1821 is preferable because not only a still image or a moving image can be displayed on the display portion 1821, but also a user can intuitively perform an operation. Further, when the device is used for providing information such as route information and traffic information, usability can be improved by intuitive operation.

Fig. 25C illustrates a notebook personal computer 1830. The personal computer 1830 includes a display portion 1831, a housing 1832, a touch panel 1833, a connection port 1834, and the like.

The touch pad 1833 is used as an input unit such as a pointing device or a tablet, and can be operated with a finger or a stylus pen.

The touchpad 1833 is assembled with a display element. As shown in fig. 25C, the touch pad 1833 can be used as a keyboard by displaying input keys 1835 on the surface of the touch pad 1833. At this time, a vibration module may be incorporated in the touch pad 1833 in order to reproduce a tactile sensation by vibration when the input key 1835 is touched.

Fig. 26A and 26B show a portable information terminal 800. The portable information terminal 800 includes a housing 801, a housing 802, a display unit 803, a display unit 804, a hinge unit 805, and the like.

The frame 801 and the frame 802 are connected by a hinge 805. The portable information terminal 800 can be converted from the folded state shown in fig. 26A to the state in which the housing 801 and the housing 802 are unfolded as shown in fig. 26B.

For example, file information can be displayed on the display unit 803 and the display unit 804, whereby the portable information terminal can be used as an electronic book reader. Further, a still image or a moving image may be displayed on the display unit 803 and the display unit 804.

In this way, since the portable information terminal 800 can be folded when carried, the versatility is excellent.

The housings 801 and 802 may include a power button, an operation button, an external connection port, a speaker, a microphone, and the like.

Fig. 26C shows an example of a portable information terminal. The portable information terminal 810 shown in fig. 26C includes a housing 811, a display portion 812, operation buttons 813, an external connection port 814, a speaker 815, a microphone 816, a camera 817, and the like.

The portable information terminal 810 has a touch sensor in the display portion 812. Various operations such as making a call or inputting characters can be performed by touching the display portion 812 with a finger, a stylus, or the like.

Further, by operating the button 813, ON/OFF operation of the power supply or switching of the type of image displayed ON the display portion 812 can be performed. For example, the writing screen of the email may be switched to the main menu screen.

Further, by providing a detection device such as a gyro sensor or an acceleration sensor inside the portable information terminal 810, the direction (vertical or horizontal) of the portable information terminal 810 can be determined, and the screen display direction of the display portion 812 can be automatically switched. The screen display direction may be switched by touching the display portion 812, operating the operation buttons 813, or inputting sound using the microphone 816.

The portable information terminal 810 has, for example, one or more functions selected from a telephone set, a notebook, an information reading device, and the like. Specifically, the portable information terminal 810 may be used as a smart phone. The portable information terminal 810 can execute various application programs such as a mobile phone, an electronic mail, reading and editing of a text, music playing, animation playing, network communication, and a computer game.

Fig. 26D shows an example of a camera. The camera 820 includes a housing 821, a display unit 822, an operation button 823, a shutter button 824, and the like. The camera 820 is attached with a detachable lens 826.

Although the camera 820 has a structure in which the lens 826 is detachable from and replaceable with the housing 821, the lens 826 and the housing 821 may be integrally formed.

By pressing the shutter button 824, the camera 820 can capture a still image or a moving image. Further, the display unit 822 may have a touch panel function, and imaging may be performed by touching the display unit 822.

The camera 820 may further include a flash unit and a viewfinder, which are separately installed. These members may be incorporated in the frame 821.

Fig. 26E shows an example in which a display device according to an embodiment of the present invention is mounted as an in-vehicle display. The display portions 832 and 833 display navigation information, a speedometer, a tachometer, a travel distance, a fuel gauge, a gear state, setting of an air conditioner, and the like, and thus various information can be provided. The user can change the display contents and arrangement appropriately according to the preference. The display device according to one embodiment of the present invention can be used in a wide temperature range, and can display reliably in both a low-temperature environment and a high-temperature environment. Thus, the safety of traveling can be improved by using the display device according to one embodiment of the present invention as an in-vehicle display.

As described above, an electronic device can be obtained by applying the display device according to one embodiment of the present invention. The display device has a wide application range, and can be applied to electronic devices in all fields.

This embodiment mode can be combined with other embodiment modes as appropriate.

[ examples ]

In this example, a result of manufacturing a display device which is one embodiment of the present invention will be described.

The display device manufactured in this embodiment is a liquid crystal display device of FFS mode as follows: a screen size with a diagonal of 10.2 inches; the effective pixel number is 720 (H). times.RGB.times.1920 (V); pixel size 42 μm (H) x 126 μm (V); the resolution was 201 ppi; the aperture ratio was 46.2%.

The gate driver is built-in and the source driver is an external IC. The frame frequency was 60 Hz.

The structure of the pixel circuit corresponds to the circuit diagram of the pixel 11b shown in fig. 8A. The display device of the present embodiment can display an image signal with a correction signal added thereto (see fig. 8B). The top-down layout of the pixels corresponds to the structure of fig. 9A to 9C. The cross-sectional structure of the pixel corresponds to the structure shown in fig. 10.

A liquid crystal material having a saturation voltage of approximately 10V is used as the liquid crystal material. Although the saturation voltage may be about 5V in the FFS mode liquid crystal display device, a liquid crystal material may be selected so that the liquid crystal element has a high driving voltage in order to confirm that a high voltage is applied to the liquid crystal element when a correction signal is added to an image signal.

Fig. 27A shows a display result when display is performed using only an image signal without adding a correction signal. Fig. 27B shows a display result when the correction signal is added to the image signal and the image signal is displayed. The display of fig. 27B is brighter than fig. 27A. It can be said that when only the image signal is used, a sufficient voltage cannot be applied to the liquid crystal element, and when the correction signal is added to the image signal, a higher voltage is applied to the liquid crystal element, whereby display luminance is improved. As is apparent from fig. 27A and 27B, by adding a correction signal to an image signal, a higher voltage can be applied to the liquid crystal element than in the case of using only an image signal, and thus high-luminance display can be performed.

When the display is performed using only the image signal without adding the correction signal, the luminance in the white display is 76cd/m²The contrast is 35: 1. on the other hand, when the correction signal is added to the image signal and the image signal is displayed, the luminance in white display is 344cd/m²The contrast is 114: 1. it is thus understood that contrast is improved in a display device having a high driving voltage by adding a correction signal to an image signal.

[ description of symbols ]

10: display device, 11: pixel, 11 a: pixel, 11 b: pixel, 30: backlight unit, 31: substrate, 32: substrate, 35: light, 38: light-shielding layer, 39: coloring layer, 41: pixel electrode, 42: liquid crystal layer, 43: common electrode, 43 a: common electrode, 43 b: conductive layer, 44: insulating layer, 45: insulating layer, 46: conductive layer, 46 a: conductive layer, 46 b: conductive layer, 46 c: conductive layer, 61: polarizing plate, 63: polarizing plate, 71: connection portion, 72: connecting part, 73: connection part, 74: connection part, 100: display area, 101: transistor, 102: transistor, 104: capacitive element, 105: capacitive element, 106: liquid crystal element, 121: wiring, 122: wiring, 124: wiring, 125: wiring, 126: wiring, 133 a: alignment film, 133 b: alignment film, 135: protective layer, 141: adhesive layer, 162: display unit, 164: drive circuit unit, 172: FPC, 211: gate insulating layer, 212: insulating layer, 213: insulating layer, 214: insulating layer, 215: insulating layer, 217: insulating layer, 218: insulating layer, 221: gate, 221 a: gate, 221 b: gate, 222 a: conductive layer, 222 b: conductive layer, 222 c: conductive layer, 222 d: conductive layer, 222 e: conductive layer, 222 f: conductive layer, 222 g: conductive layer, 223: gate, 223 a: gate, 223 b: gate, 225: gate insulating layer, 225 a: gate insulating layer, 225 b: gate insulating layer, 231: semiconductor layer, 231 a: semiconductor layer, 231 b: semiconductor layer, 231 i: channel formation region, 231 n: low-resistance region, 233: gate, 235: gate insulating layer, 242: connector, 800: portable information terminal, 801: frame, 802: frame, 803: display unit, 804: display section, 805: hinge section, 810: portable information terminal, 811: frame body, 812: display unit, 813: operation buttons, 814: external connection port, 815: loudspeaker, 816: microphone, 817: camera, 820: camera, 821: frame body 822: display unit, 823: operation buttons, 824: shutter button, 826: lens, 832: display section, 833: display unit, 1810: television apparatus, 1811: display unit, 1812: frame, 1813: speaker, 1814: remote controller, 1820: digital signage, 1821: display section, 1822: column, 1830: personal computer, 1831: display unit, 1832: frame body, 1833: touchpad, 1834: connection port, 1835: input key

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