Display device including backlight unit
阅读说明：本技术 包括背光单元的显示设备 (Display device including backlight unit ) 是由 朴镇浩 黄星龙 姜韩率 孙珠渊 安在设 于 2020-03-10 设计创作，主要内容包括：本申请涉及显示设备。该显示设备包括：显示面板；导光板,位于显示面板下面；光源,在第一方向上与导光板间隔开；多个第一光学图案,位于导光板下面,同时在第一方向上延伸且布置在与第一方向相交的第二方向上；以及多个第二光学图案,位于多个第一光学图案下面。当在第一方向上观察时,多个第一光学图案中的每一个具有四边形形状。(The present application relates to a display device. The display device includes: a display panel; a light guide plate positioned under the display panel; a light source spaced apart from the light guide plate in a first direction; a plurality of first optical patterns located under the light guide plate while extending in a first direction and arranged in a second direction crossing the first direction; and a plurality of second optical patterns positioned under the plurality of first optical patterns. Each of the plurality of first optical patterns has a quadrangular shape when viewed in the first direction.)
1. A display device, comprising:
a display panel;
a light guide plate positioned under the display panel;
a light source spaced apart from the light guide plate in a first direction;
a plurality of first optical patterns under the light guide plate, the plurality of first optical patterns extending in the first direction and arranged in a second direction intersecting the first direction; and
a plurality of second optical patterns positioned under the plurality of first optical patterns,
wherein each of the plurality of first optical patterns has a quadrangular shape when viewed in the first direction.
2. The display device of claim 1, wherein the plurality of second optical patterns are spaced apart from each other along the first direction and the second direction.
3. The display apparatus according to claim 1, wherein each of the plurality of first optical patterns and the plurality of second optical patterns has a refractive index equal to or greater than a refractive index of the light guide plate.
4. The display device of claim 1, wherein each of the plurality of second optical patterns comprises a base resin and scattering particles.
5. The display device of claim 1, wherein the plurality of second optical patterns comprise a same material as a material of the plurality of first optical patterns.
6. The display device of claim 1, wherein each of the plurality of second optical patterns comprises an outermost surface having a curvature.
7. The display apparatus of claim 1, wherein a width of each of the plurality of second optical patterns is equal to or less than twenty times a height of each of the plurality of second optical patterns.
8. The display device of claim 1, further comprising a base layer between the light guide plate and the plurality of first optical patterns, the base layer comprising a same material as a material of the plurality of first optical patterns.
9. The display device of claim 1, further comprising:
a low refractive index layer on the light guide plate, the low refractive index layer having a refractive index smaller than a refractive index of the light guide plate; and
a wavelength conversion layer on the low refractive index layer, the wavelength conversion layer including wavelength conversion particles that convert a wavelength of light provided from the light source.
10. The display device of claim 1, wherein an angle between a side surface of each of the plurality of first optical patterns and a plane parallel to the first and second directions is in a range between 75 degrees and 90 degrees.
11. The display apparatus according to claim 1, wherein the light guide plate comprises:
a first side surface facing the light source; and
a second side surface spaced apart from the first side surface in the first direction,
wherein a portion of the light provided from the light source travels from the first side surface toward the second side surface through the plurality of first optical patterns and the light guide plate, and
wherein a portion of the light provided from the light source travels toward the display panel through the plurality of second optical patterns.
12. The display device according to claim 11,
the plurality of second optical patterns have the same size, an
In a plane, the number of the plurality of second optical patterns disposed in a region adjacent to the second side surface is greater than the number of the plurality of second optical patterns disposed in a region adjacent to the first side surface.
13. The display apparatus of claim 11, wherein a size of some of the plurality of second optical patterns is smaller than a size of other of the plurality of second optical patterns,
the some of the plurality of second optical patterns are disposed in a region adjacent to the first side surface,
the other second optical patterns of the plurality of second optical patterns are disposed in a region adjacent to the second side surface.
Technical Field
Exemplary embodiments of the present invention relate to a backlight unit, a display apparatus including the same, and a method of manufacturing the backlight unit.
Background
The light receiving type display device includes a display panel displaying an image using external light and a backlight unit supplying light to the display panel. The display panel includes a plurality of pixels for generating an image. The pixels display an image by adjusting transmittance of light supplied from the backlight unit.
The backlight unit is roughly classified into an edge type backlight unit and a direct type backlight unit. The edge type backlight unit includes a light guide plate and a light source adjacent to one surface of the light guide plate. One surface of the light guide plate is defined as a light incident part, and light generated from the light source is supplied to the light guide plate through the light incident part.
Disclosure of Invention
When the edge type backlight unit is used, the optical density is highest at the light incident part of the light guide plate. In this case, the increased amount of light is discharged upward through a specific portion of the light guide plate near the light incident part. Accordingly, since light leakage occurs at a portion close to the light incident portion of the light guide plate, luminance efficiency may be reduced.
Exemplary embodiments of the present invention provide a backlight unit having improved luminance uniformity and a display apparatus including the same.
Exemplary embodiments of the present invention provide a simplified method of manufacturing a backlight unit.
An exemplary embodiment of the present invention provides a display device including: a display panel; a light guide plate positioned under the display panel; a light source spaced apart from the light guide plate in a first direction; a plurality of first optical patterns located under the light guide plate, the plurality of first optical patterns extending in a first direction and arranged in a second direction intersecting the first direction; and a plurality of second optical patterns positioned under the plurality of first optical patterns. Each of the plurality of first optical patterns may have a quadrangular shape when viewed in the first direction.
In an exemplary embodiment, the plurality of second optical patterns may be spaced apart from each other along the first and second directions.
In an exemplary embodiment, each of the plurality of first optical patterns and the plurality of second optical patterns may have a refractive index equal to or greater than a refractive index of the light guide plate.
In an exemplary embodiment, each of the plurality of second optical patterns may include a base resin and scattering particles.
In an exemplary embodiment, the plurality of second optical patterns may include the same material as that of the plurality of first optical patterns.
In an exemplary embodiment, each of the plurality of second optical patterns may include an outermost surface having a curvature.
In an exemplary embodiment, a width of each of the plurality of second optical patterns may be equal to or less than 20 times a height of each of the plurality of second optical patterns.
In an exemplary embodiment, the display apparatus may further include a base layer between the light guide plate and the plurality of first optical patterns. The base layer may include the same material as that of the plurality of first optical patterns.
In an exemplary embodiment, the display apparatus may further include: a low refractive index layer on the light guide plate, the low refractive index layer having a refractive index smaller than that of the light guide plate; and a wavelength conversion layer on the low refractive index layer. The wavelength conversion layer may include wavelength conversion particles that convert a wavelength of light provided from the light source.
In an exemplary embodiment, an angle between a side surface of each of the plurality of first optical patterns and a plane parallel to the first and second directions may be about 75 degrees (c°) And about 90°Within the range of (a).
In an exemplary embodiment, the light guide plate may include a first side surface facing the light source and a second side surface spaced apart from the first side surface in the first direction. A portion of the light provided from the light source may travel from the first side surface toward the second side surface through the plurality of first optical patterns and the light guide plate. A portion of the light provided from the light source may travel toward the display panel through the plurality of second optical patterns.
In an exemplary embodiment, the plurality of second optical patterns may be substantially the same in size. In a plane, the number of the plurality of second optical patterns disposed in the region adjacent to the second side surface may be greater than the number of the plurality of second optical patterns disposed in the region adjacent to the first side surface.
In an exemplary embodiment, the size of some of the plurality of second optical patterns may be smaller than the size of other of the plurality of second optical patterns. Some of the plurality of second optical patterns may be disposed in a region adjacent to the first side surface, and other of the plurality of second optical patterns may be disposed in a region adjacent to the second side surface.
An exemplary embodiment of the present invention provides a method of manufacturing a backlight unit, the method including: forming a light guide plate; forming a plurality of first optical patterns on one surface of a light guide plate; and forming a plurality of second optical patterns on the plurality of first optical patterns. The plurality of first optical patterns may extend along a first direction and be arranged along a second direction intersecting the first direction. Each of the plurality of first optical patterns may have a quadrangular shape when viewed in the first direction.
In an exemplary embodiment, forming the plurality of second optical patterns may include printing ink on the plurality of first optical patterns. The ink may include scattering particles.
In an exemplary embodiment, the method of manufacturing a backlight unit may further include: forming a mold having a shape corresponding to the shapes of the plurality of first optical patterns and the shapes of the plurality of second optical patterns; and forming an initial layer on one surface of the light guide plate. Forming the plurality of first optical patterns and the plurality of second optical patterns may include imprinting the initial layer using a mold.
In an exemplary embodiment, forming the mold may include: forming a plurality of first stamp patterns extending in a first direction and arranged in a second direction on a substrate, each of the plurality of first stamp patterns having a quadrangular shape when viewed in the first direction; printing ink on the plurality of first stamp patterns to form a plurality of second stamp patterns; and forming a mold having an engraved shape corresponding to the shape of the plurality of first stamp patterns and the shape of the plurality of second stamp patterns using the plurality of first stamp patterns and the plurality of second stamp patterns.
An exemplary embodiment of the present invention provides a display device including: a light guide plate; a light source spaced apart from the light guide plate in a first direction; a low refractive index layer on the light guide plate, the low refractive index layer having a refractive index smaller than that of the light guide plate; a wavelength conversion layer on the low refractive index layer, the wavelength conversion layer including wavelength conversion particles that convert a wavelength of light provided from the light source; a plurality of first optical patterns located under the light guide plate, the plurality of first optical patterns extending in a first direction and arranged in a second direction intersecting the first direction; and a plurality of second optical patterns positioned under the plurality of first optical patterns, the plurality of second optical patterns being arranged along the first direction and the second direction. Each of the plurality of first optical patterns may have a quadrangular shape when viewed in the first direction.
In an exemplary embodiment, each of the plurality of second optical patterns may include a base resin and scattering particles.
In an exemplary embodiment, the plurality of second optical patterns may include the same material as that of the plurality of first optical patterns. Each of the plurality of second optical patterns may have an outermost surface having a curvature.
Drawings
The above and other exemplary embodiments, advantages and features of the present disclosure will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which:
fig. 1 shows a perspective view illustrating an exemplary embodiment of a display device according to the present invention.
Fig. 2 shows a schematic diagram illustrating the pixel depicted in fig. 1.
Fig. 3 shows a cross-sectional view illustrating the wavelength conversion layer depicted in fig. 1.
Fig. 4A illustrates a plan view partially showing an exemplary embodiment of a backlight unit according to the present invention.
Fig. 4B shows a cross-sectional view taken along line I-I' of fig. 4A.
Fig. 5 shows a cross-sectional view taken along a portion corresponding to line I-I' of fig. 4A.
Fig. 6A shows an enlarged cross-sectional view partially illustrating an exemplary embodiment of an optical layer according to the present invention.
Fig. 6B shows an enlarged cross-sectional view, partially illustrating an exemplary embodiment of an optical layer according to the present invention.
Fig. 7 illustrates a plan view partially showing an exemplary embodiment of a backlight unit according to the present invention.
Fig. 8 illustrates a cross-sectional view partially showing an exemplary embodiment of a backlight unit according to the present invention.
Fig. 9 illustrates a plan view partially showing an exemplary embodiment of a backlight unit according to the present invention.
Fig. 10 illustrates a plan view partially showing an exemplary embodiment of a backlight unit according to the present invention.
Fig. 11A to 11C illustrate cross-sectional views showing an exemplary embodiment of a method of manufacturing a portion of a backlight unit according to the present invention.
Fig. 12A to 12G illustrate cross-sectional views showing an exemplary embodiment of a method of manufacturing a portion of a backlight unit according to the present invention.
Detailed Description
In the present specification, when a particular component (or region, layer, portion, etc.) is referred to as being "on," "connected to," or "coupled to" another component(s), the particular component may be directly disposed on, connected or coupled to the other component(s), or at least one intermediate component may be present therebetween.
Like reference numerals refer to like elements. In addition, in the drawings, thicknesses, ratios, and sizes of components are exaggerated in order to effectively explain technical contents.
The term "and/or" includes one or more combinations defined by the associated components.
It will be understood that, although the terms first, second, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another. For example, a first component may be termed a second component, and vice-versa, without departing from the scope of the present invention. The singular is intended to include the plural unless the context clearly dictates otherwise.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms, including "at least one", unless the context clearly indicates otherwise. "or" means "and/or". As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Furthermore, the terms "lower," "above," "upper," and the like are used herein to describe one element's relationship to another element(s) as illustrated in the figures. Relative terms are intended to encompass different orientations in addition to the orientation depicted in the figures.
As used herein, "about" or "about" includes the average value over an acceptable range of deviation of the stated value and the specified value as determined by one of ordinary skill in the art in view of the measurement in question and the error associated with measurement of the specified quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ± 30%, ± 20%, ± 10%, ± 5% of the stated value.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. Furthermore, terms defined in general dictionaries should be interpreted as having a meaning that is consistent with or equal to the meaning defined below in the art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It will be further understood that the terms "comprises," "comprising," "includes," "including," "has," "having," and the like, are used to specify the presence of stated features, integers, steps, operations, components, elements, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, elements, or groups thereof.
Now, exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.
Fig. 1 shows a perspective view illustrating an exemplary embodiment of a display device according to the present invention.
Referring to fig. 1, the display device DD may include a display panel DP, a gate driver GD, a data driver SD, a printed circuit board PCB, and a backlight unit BLU.
The display panel DP may be shaped like a plate having a plane defined by the first direction DR1 and the second direction DR 2. In fig. 1, the display device DD is shown to have a flat shape, but the present invention is not limited thereto. In other exemplary embodiments, the display device DD may be a curved display device. In an exemplary embodiment, the display device DD may be a display device that is concavely or convexly curved as a whole, from a perspective of a user facing the display device DD. In alternative exemplary embodiments, the display device DD may be a partially curved display device, for example.
The display panel DP may be a light receiving type display panel. The display panel DP may transmit or block light received from the display panel DP, thereby providing an image. In an exemplary embodiment, the display panel DP may be a liquid crystal display panel, for example, but the present invention is not limited thereto. The display panel DP may generate an image corresponding to input image data and provide the generated image on a front surface thereof. In an exemplary embodiment, for example, the display panel DP may provide the generated image to the third direction DR 3.
The display panel DP may include a first substrate SUB1, a second substrate SUB2 facing the first substrate SUB1, and a liquid crystal layer LC between the first substrate SUB1 and the second substrate SUB 2.
A plurality of pixels PX, a plurality of gate lines GL1 to GLm, and a plurality of data lines DL1 to DLn may be disposed on the
The gate lines GL1 to GLm may be insulated from the data lines DL1 to DLn and intersect the data lines DL1 to DLn. The gate lines GL1 to GLm may extend in the second direction DR2 and be electrically connected with the gate driver GD. The data lines DL1 to DLn may extend in the first direction DR1 and be electrically connected with the data driver SD. Each of the pixels PX may be electrically connected to a corresponding gate line of the gate lines GL1 to GLm and to a corresponding data line of the data lines DL1 to DLn.
The gate driver GD may be disposed on a portion of the first substrate SUB1 adjacent to one side of the
In other exemplary embodiments, the gate driver GD may be provided in the shape of a plurality of driver chips disposed (e.g., mounted) on a flexible circuit board, and a tape carrier package ("TCP") scheme is employed to connect the gate driver GD to the
The data driver SD may include a plurality of source driver chips S-IC disposed (e.g., mounted) on the flexible circuit board FPC. Fig. 1 exemplarily shows four source driver chips S-ICs and four flexible circuit boards FPC, but the number of the source driver chips S-ICs and the flexible circuit boards FPC may vary according to the size of the display panel DP.
One side of the flexible circuit board FPC may be connected to one side of the
A timing controller (not shown) may be provided on the printed circuit board PCB. A timing controller in the shape of an integrated circuit chip may be disposed (e.g., mounted) on the printed circuit board PCB. The timing controller may be electrically connected to the gate driver GD and the data driver SD through a flexible circuit board FPC. The timing controller may output a gate control signal to the gate driver GD and output a data control signal and image data to the data driver SD.
The gate driver GD may receive a gate control signal from the timing controller, and may generate a plurality of gate signals in response to the gate control signal. The gate driver GD may sequentially output gate signals. The gate signal may be supplied to the pixel PX through the gate lines GL1 to GLm.
The data driver SD may receive image data and a data control signal from the timing controller. In response to the data control signal, the data driver SD may generate analog data voltages corresponding to image data and output the data voltages to the data lines DL1 to DLn. The data voltage may be supplied to the pixels PX through the data lines DL1 to DLn.
In response to gate signals supplied through the gate lines GL1 to GLm, data voltages may be supplied to the pixels PX through the data lines DL1 to DLn.
The backlight unit BLU may provide light to the display panel DP. In an exemplary embodiment, the backlight unit BLU may be an edge type backlight unit, for example.
The backlight unit BLU may include a light source unit LSU, a light guide plate LGP, a low refractive index layer LRL, a wavelength conversion layer LCL, an optical sheet OS, and an optical layer OL.
The light source unit LSU may be disposed to be spaced apart from the light guide plate LGP in the
The light source unit LSU may include a light source substrate LSB extending in the second direction DR2 and a plurality of light sources LS located on the light source substrate LSB. The light sources LS may be disposed at regular intervals in the second direction DR 2. The light source LS may be disposed to face the first side surface S1 of the light guide plate LGP. The light sources LS may each generate first light, and the first light may be provided to the first side surface S1 of the light guide plate LGP.
The light guide plate LGP may include transparent plastic or glass. The light guide plate LGP may be disposed under the display panel DP. The light guide plate LGP may have top and bottom surfaces, each of which is a plane defined by the first and second directions DR1 and DR 2. Accordingly, the third direction DR3 may be a direction perpendicular to the top and bottom surfaces of the light guide plate LGP.
The low refractive index layer LRL may be disposed between the display panel DP and the light guide plate LGP. The low refractive index layer LRL may be disposed on the light guide plate LGP and in contact with a top surface of the light guide plate LGP.
The low refractive index layer LRL may have a refractive index smaller than that of the light guide plate LGP. In an exemplary embodiment, for example, the refractive index of the light guide plate LGP may be in a range between about 1.49 and about 1.5, and the refractive index of the low refractive index layer LRL may be about 1.25, for example. The low refractive index layer LRL may be a porous low refractive index layer. A portion of the light traveling toward the top surface of the light guide plate LGP may be totally reflected from an interface between the light guide plate LGP and the low refractive index layer LRL. In an exemplary embodiment, for example, the first light may be provided to the low refractive layer LRL or may be totally reflected from an interface between the light guide plate LGP and the low refractive layer LRL depending on an exit angle of the first light. The totally reflected light may travel toward the second side surface S2 of the light guide plate LGP.
The wavelength conversion layer LCL may be disposed between the display panel DP and the low refractive index layer LRL. The wavelength conversion layer LCL may be placed on the low refractive index layer LRL and in contact with the top surface of the low refractive index layer LRL.
The light provided to the low refractive index layer LRL may be directed towards the wavelength conversion layer LCL. The wavelength conversion layer LCL may convert the first light into white light and output the white light upward. The white light may diffuse in the wavelength conversion layer LCL and may exit upwards. In an exemplary embodiment, for example, the first light may be blue light.
The wavelength conversion layer LCL may comprise a plurality of dots converting blue light into white light. The light converted in the wavelength conversion layer LCL may be provided to the optical sheet OS.
The optical sheet OS may be disposed between the display panel DP and the wavelength conversion layer LCL. The optical sheet OS may include a diffusion sheet and a prism sheet on the diffusion sheet. The diffusion sheet may be used to diffuse the white light provided from the wavelength conversion layer LCL. The prism sheet may concentrate white light diffused from the diffusion sheet in an upward direction perpendicular to the plane. The white light passing through the prism sheet may travel in an upward direction, and then the white light having a uniform luminance distribution may be provided to the display panel DP. In other exemplary embodiments, the optical sheet OS may be omitted.
The optical layer OL may be disposed under the light guide plate LGP. The optical layer OL may guide the first light incident on the first side surface S1 to travel toward the second side surface S2 and to travel toward the display panel DP. The configuration of the optical layer OL will be discussed in further detail.
Fig. 2 shows a schematic diagram illustrating the pixel depicted in fig. 1.
For convenience of description, fig. 2 shows the pixel PX connected to the gate line GLi and the data line DLj, and the other pixels PX of the display panel DP may be configured the same as the pixels PX shown in fig. 2.
Referring to fig. 2, the pixel PX may include a transistor TR connected to the gate line GLi and the data line DLj, a liquid crystal capacitor Clc electrically connected to the transistor TR, and a storage capacitor Cst electrically connected in parallel to the liquid crystal capacitor Clc. In other exemplary embodiments, the storage capacitor Cst may be omitted. "i" and "j" are natural numbers.
The transistor TR may be provided on the
The liquid crystal capacitor Clc may include a pixel electrode PE disposed on the first substrate SUB1, a common electrode CE disposed on the second substrate SUB2, and a liquid crystal layer LC disposed between the pixel electrode PE and the common electrode CE. The pixel electrode PE may be electrically connected to an output electrode of the transistor TR.
In fig. 2, the pixel electrode PE is exemplarily illustrated in a shape of a non-slit structure, but the shape of the pixel electrode PE is not limited thereto. In an exemplary embodiment, for example, the pixel electrode PE may have a slit structure including a cross-shaped bar (stem) and a plurality of branches radially extending from the bar.
The common electrode CE may be disposed under the second substrate SUB 2. In an alternative exemplary embodiment, the common electrode CE may be disposed on the
The storage capacitor Cst may include the pixel electrode PE, a storage electrode (not shown) branched from a storage line (not shown), and a dielectric layer disposed between the pixel electrode PE and the storage electrode. The storage line may be disposed on the first substrate SUB1, and the storage line and the gate line (refer to GL1 to GLm of fig. 1) may be disposed simultaneously with each other on the same layer. The storage electrode may partially overlap the pixel electrode PE. A storage voltage having a constant voltage level may be supplied to the storage line. In an alternative exemplary embodiment, a common voltage may be supplied to the storage lines. The storage capacitor Cst may serve to supplement the charge amount of the liquid crystal capacitor Clc.
The pixel PX may further include a color filter CF displaying one of red, green, and blue colors. In an exemplary embodiment, as shown in fig. 2, the color filter CF may be disposed on the second substrate SUB 2. In other exemplary embodiments, the color filter CF may be disposed on the
The transistor TR may be turned on in response to a gate signal supplied through the gate line GLi. The data voltage received through the data line DLj may be supplied to the pixel electrode PE of the liquid crystal capacitor Clc through the turned-on transistor TR. The common electrode CE may be supplied with a common voltage.
A difference in voltage levels of the data voltage and the common voltage may generate an electric field between the pixel electrode PE and the common electrode CE. An electric field generated between the pixel electrode PE and the common electrode CE may change the orientation of liquid crystal molecules of the liquid crystal layer LC. The liquid crystal molecules driven by the electric field may adjust optical transmittance, thereby displaying an image.
Fig. 3 shows a cross-sectional view illustrating the wavelength conversion layer depicted in fig. 1.
Referring to fig. 3, the wavelength conversion layer LCL may include a first barrier layer BR1, a second barrier layer BR2 disposed over the first barrier layer BR1, a base resin RN disposed between the first barrier layer BR1 and the second barrier layer BR2, a first luminescent material QD1, a second luminescent material QD2, and scattering particles SP.
Each of first barrier layer BR1 and second barrier layer BR2 may have a single layer structure or a multilayer structure. Each of first barrier layer BR1 and second barrier layer BR2 may include an inorganic material. In an exemplary embodiment, the inorganic material may be, for example, silicon nitride or silicon oxide.
The base resin RN may be a polymer resin. In exemplary embodiments, the base resin RN may be, for example, an acryl-based resin, a urethane-based resin, a silicon-based resin, or an epoxy-based resin. The base resin RN may be a transparent resin. The first luminescent substance QD1, the second luminescent substance QD2, and the scattering particles SP may be distributed in the base resin RN.
The first and second light emitting substances QD1 and QD2 may include a material that absorbs light to convert the wavelength thereof to emit light. In an exemplary embodiment, for example, the first and second light emitting substances QD1 and QD2 may be quantum dots.
The first luminescent substance QD1 may absorb the first light L1 to emit the second light L2. The second light emitting substance QD2 may absorb the first light L1 to emit the third light L3. The second light L2 may be red light, and the third light L3 may be green light. The first light L1, the second light L2, and the third light L3 may be mixed to generate white light.
The scattering particles SP may scatter light. In an exemplary embodiment, the scattering particles SP may include SiO2、TiO2Organic beads, or combinations thereof. In an exemplary embodiment, the organic beads may include, for example, polymethylmethacrylate ("PMMA").
Fig. 4A illustrates a plan view partially showing an exemplary embodiment of a backlight unit according to the present invention. Fig. 4B shows a cross-sectional view taken along line I-I' of fig. 4A.
Referring to fig. 4A and 4B, the optical layer OL may include a base layer BS, a first optical pattern OP1, and a second optical pattern OP 2.
The base layer BS may be in contact with a bottom surface of the light guide plate LGP. The first optical pattern OP1 may protrude downward from the base layer BS. The base layer BS and the first optical pattern OP1 may be integral. The base layer BS may be connected to all the first optical patterns OP1 spaced apart from each other. Accordingly, one or more of the first optical patterns OP1 may be prevented from being separated from the light guide plate LGP.
The base layer BS and the first optical pattern OP1 may include the same material. In an exemplary embodiment, for example, the base layer BS and the first optical patterns OP1 may include a material having a refractive index equal to or greater than that of the light guide plate LGP.
Each of the first optical patterns OP1 may extend along the
The first optical pattern OP1 may have a quadrangular shape when viewed in the
The number of the first optical patterns OP1 may be greater than the number of the light sources LS. A predetermined number of first optical patterns OP1 may be disposed under the light guide plate LGP corresponding to a single light source LS. Although 8 light sources LS and 24 first optical patterns OP1 are exemplarily shown, the number of the light sources LS and the first optical patterns OP1 is not limited thereto. Further, although 16 second optical patterns OP2 are exemplarily shown, the number of the second optical patterns OP2 is not limited thereto.
The second optical pattern OP2 may be disposed under the first
The second optical patterns OP2 may be spaced apart from each other along the first and second directions DR1 and DR 2. The size of the second optical pattern OP2 may be different according to location. In an exemplary embodiment, for example, the size of the second optical pattern OP2 may vary based on the distance from the light source LS. The longer the distance from the light source LS, the larger the size of the second optical pattern OP 2. In an exemplary embodiment, the size of the second optical pattern OP2 disposed in the first area AR1 adjacent to the first side surface S1 may be smaller than the size of the second optical pattern OP2 disposed in the second area AR2 adjacent to the second side surface S2.
Fig. 5 shows a cross-sectional view taken along a portion corresponding to line I-I' of fig. 4A.
Referring to fig. 5, the optical layer OLa may include a base layer BS, a first optical pattern OP1, and a second optical pattern OP2 a.
The base layer BS, the first optical pattern OP1, and the second optical pattern OP2a may be integrated. Accordingly, the base layer BS, the first optical pattern OP1, and the second optical pattern OP2a may include the same material. In an exemplary embodiment, for example, the base layer BS, the first optical patterns OP1, and the second optical patterns OP2a may include a material having a refractive index equal to or greater than a refractive index of the light guide plate LGP.
The light incident on the second optical pattern OP2a may be totally reflected from the outermost surface of the second optical pattern OP2a, and then be guided toward the display panel (refer to DP of fig. 1). Each of the second optical patterns OP2a may include an outermost surface having a curvature.
Since the second optical pattern OP2a does not include scattering particles, the second optical pattern OP2a may have a convex shape that is more convex than the convex shape of the second optical pattern OP2 shown in fig. 4B. In an exemplary embodiment, for example, the width WT-O of each of the second optical patterns OP2a may be equal to or less than 20 times the height HT-O of each of the second optical patterns OP2 a. The width WT-O may be a maximum width parallel to the second direction DR 2. The height HT-O may correspond to a maximum distance parallel to the third direction DR3 between a plane parallel to the bottom surface of the first optical pattern OP1 and the outermost surface of the second optical pattern OP2 a.
Fig. 6A shows an enlarged cross-sectional view partially illustrating an exemplary embodiment of an optical layer according to the present invention. For convenience of description, fig. 6A exaggeratedly shows a portion of the optical layer OL on which the two first optical patterns OP1 are disposed.
Referring to fig. 6A, each of the first optical patterns OP1 may have symmetrical first and second side surfaces SL1 and SL2, the first and second side surfaces SL1 and SL2 being defined by opposite inclined sides of an inverted trapezoidal shape. In an exemplary embodiment, for example, the first and second side surfaces SL1 and SL2 may have an inclination angle AG with respect to a plane parallel to the first and second directions DR1 and DR 2. In an exemplary embodiment, for example, the inclination angle AG may be in a range between about 70 ° and about 90 °.
A width WT of each of the first optical patterns OP1 may be defined to indicate a distance between the top of the first side surface SL1 and the top of the second side surface SL2 along the second direction DR 2. The top end may be a portion in contact with the base layer BS. The thickness TH of each of the first optical patterns OP1 may be defined to indicate a distance between the top and bottom surfaces of each first optical pattern OP1 along the third direction DR 3.
The width WT of each of the first optical patterns OP1 may be greater than the thickness TH of each of the first
For example, a distance between the top end of the first side surface SL1 of the h-th first optical pattern and the top end of the first side surface SL1 of the (h +1) -th first optical pattern along the second direction DR2 may be defined to indicate a pitch PIT of the first optical patterns OP1, and the pitch PIT may be in a range between about 20 μm and about 500 μm. Here, h may be a natural number. In the first optical pattern OP1 shown in fig. 6A, the h-th first optical pattern may be the first optical pattern placed on the left side, and the (h +1) -th first optical pattern may be the first optical pattern placed on the right side.
Fig. 6B shows an enlarged cross-sectional view, partially illustrating an exemplary embodiment of an optical layer according to the present invention.
For convenience of description, FIG. 6B exaggeratedly shows a portion of the optical layer OL-1 on which the two first optical patterns OP1-1 are disposed.
Referring to fig. 6B, each of the first optical patterns OP1-1 may have asymmetric first and second side surfaces SL1-1 and SL2-1, the first and second side surfaces SL1-1 and SL2-1 being defined by opposite inclined sides of an inverted trapezoidal shape. In an exemplary embodiment, for example, the first and second side surfaces SL1-1 and SL2-1 may have different inclination angles AG-1 and AG with respect to a plane parallel to the first and second directions DR1 and DR 2. In an exemplary embodiment, for example, the tilt angle AG-1 may be about 90, and the tilt angle AG may be in a range between about 75 and less than about 90.
Fig. 7 illustrates a plan view partially showing an exemplary embodiment of a backlight unit according to the present invention. Fig. 8 illustrates a cross-sectional view partially showing an exemplary embodiment of a backlight unit according to the present invention.
Fig. 7 shows a traveling direction of the first light L1 on a two-dimensional plane defined by the first direction DR1 and the second direction DR2, and fig. 8 shows a traveling direction of the first light L1 in a plan view defined by the first direction DR1 and the third direction DR 3.
Referring to fig. 7, local dimming may be defined to refer to an operation of selectively controlling the light sources LS corresponding to some blocks based on the brightness of an image to be displayed on each of the blocks divided from the display panel DP. In an exemplary embodiment, the display panel DP may include a first block overlapping the first optical pattern OP1a, a second block overlapping the first optical pattern OP1b, and a third block overlapping the first optical pattern OP1 c.
As a result of the analysis of the image to be displayed, high luminance may be required to display the image on the first and second blocks of the display panel DP, and low luminance may be required to display the image on the third block of the display panel DP. In this case, the first and second light sources LS1 and LS2 may be turned on, and the third light source LS3 may be turned off. Thus, the first and second blocks may exhibit high luminance, and the third block may exhibit low luminance.
Among the light sources LS1, LS2, and LS3, the first and second light sources LS1 and LS2 may be turned on, and the third light source LS3 may be turned off. The light guide plate LGP may be provided with first light L1 generated from the first and second light sources LS1 and LS 2. The first light L1 provided to the light guide plate LGP may be directed toward the first and second optical patterns OP1 and OP 2.
The first light L1 generated from the first light source LS1 may be provided to the three first optical patterns OP1a adjacent to the first
The first light L1 generated from the second light source LS2 may be provided to the three first optical patterns OP1b adjacent to the second light source LS 2. The first light L1 provided to the first optical pattern OP1b may be reflected by the first side surface SL1 and the second side surface SL2 of each of the first optical patterns OP1b, and then be guided by each of the first optical patterns OP1b in the
Since the third light source LS3 is in an off state, the first light L1 may not be provided from the third light source LS3 to the three first optical patterns OP1c adjacent to the third light source LS 3. However, a portion of the first light L1 generated from the second light source LS2 may be provided to the first optical pattern OP1 c. However, since the third light source LS3 is in an off state, the luminance of the area on which the first optical pattern OP1c is disposed may be relatively much lower than the luminance of the area on which the first optical patterns OP1a and OP1b are disposed.
When the first optical patterns OP1 are not disposed, the first light L1 may not be separately guided to each specific region, but may be diffused into all regions of the light guide plate LGP. Therefore, it may be difficult to perform local dimming. In contrast, when the first optical pattern OP1 is disposed, the first light L1 may be separately directed to each specific area (e.g., each block of the display panel DP), and thus may be able to control the luminance of the specific area independently of each other.
Although the first, second, and third light sources LS1, LS2, and LS3 are shown for exemplary illustration, other light sources LS may be selectively operated based on the brightness of the corresponding block to perform local dimming.
Unlike some exemplary embodiments of the present invention, when the first optical pattern (hereinafter, referred to as a first comparative optical pattern) has a curvature on an outer surface thereof, various angles may be formed between a normal line of the outer surface of the light guide plate LGP and the light output surface. In this case, a portion of the light incident on the first comparing optical pattern may be directed not to the light output part but to the display panel (refer to DP of fig. 1). This situation may cause light leakage and brightness non-uniformity. The light output surface may be parallel to a plane defined by the first direction DR1 and the second direction DR 2. In contrast, according to an exemplary embodiment of the present invention, the first side surface SL1 and the second side surface SL2 of each of the first optical patterns OP1 may have a flat shape. Further, each of the first and second side surfaces SL1 and SL2 may have an angle equal to about 75 ° or more with respect to the light output surface. Accordingly, light incident on the first and second side surfaces SL1 and SL2 may have a reduced probability of being directed toward the display panel DP. In summary, the shape of the first optical pattern OP1 may increase the amount of light guided in the
Referring to fig. 8, the optical layer OL and the boundary between the light guide plate LGP and the low refractive index layer LRL may allow the first light L1 to travel in the
Fig. 9 illustrates a plan view partially showing an exemplary embodiment of a backlight unit according to the present invention. In the description of fig. 9, those components that are the same as those discussed above with reference to fig. 4A are assigned the same reference numerals, and explanations thereof will be omitted.
Referring to fig. 9, the second optical patterns OP2-1 may have substantially the same size. The second optical patterns OP2-1 may be spaced apart from each other along the first and second directions DR1 and DR 2. The interval between the second optical patterns OP2-1 may be different according to positions. In an exemplary embodiment, distances in the second direction DR2 between the second optical patterns OP2-1 may be the same as each other, for example. Differently, distances in the first direction DR1 between the second optical patterns OP2-1 may be different from each other.
A distance in the first direction DR1 between the second optical patterns OP2-1 disposed in the first area AR1 may be defined to mean a first distance PT-1, and a distance in the first direction DR1 between the second optical patterns OP2-1 disposed in the second area AR2 may be defined to mean a second distance PT-2. The first distance PT-1 may be greater than the second distance PT-2. Accordingly, the number of the second optical patterns OP2-1 disposed in the first area AR1 may be less than the number of the second optical patterns OP2-1 disposed in the second area AR 2.
Fig. 10 illustrates a plan view partially showing an exemplary embodiment of a backlight unit according to the present invention. In the description of fig. 10, those components that are the same as those discussed above with reference to fig. 4A are assigned the same reference numerals, and explanations thereof will be omitted.
Referring to fig. 10, the second optical patterns OP2-2 may have substantially the same size. The second optical patterns OP2-2 may be irregularly arranged, but the number of the second optical patterns OP2-2 disposed in the first area AR1 may be smaller than the number of the second optical patterns OP2-2 disposed in the second area AR 2.
Fig. 11A to 11C illustrate cross-sectional views showing an exemplary embodiment of a method of manufacturing a portion of a backlight unit according to the present invention.
Referring to fig. 11A, a light guide plate LGP is provided. A low refractive index layer LRL is disposed on one surface of the light guide plate LGP. The low refractive index layer LRL may be provided by a coating process. In an exemplary embodiment, for example, the composition for the low refractive index layer LRL may be slit-coated on one surface of the light guide plate LGP, and then dried and cured to form the low refractive index layer LRL. However, the formation of the low refractive index layer LRL is not limited thereto.
A wavelength conversion layer LCL is disposed on one surface of the low refractive index layer LRL. The wavelength conversion layer LCL may be provided by a coating process, but the present invention is not limited thereto.
Referring to fig. 11B, a base layer BS and a first optical pattern OP1 are disposed on the other surface of the light guide plate LGP. The base layer BS and the first optical patterns OP1 may be disposed in the shape of a sheet attached to the other surface of the light guide plate LGP. However, the formation of the base layer BS and the first optical pattern OP1 is not limited to the example discussed above. In an exemplary embodiment, an initial layer may be disposed on one surface of the light guide plate LGP, and then the initial layer may be embossed to form the base layer BS and the first
Referring to fig. 11C, a second optical pattern OP2 is disposed on the first optical pattern OP1 and the base layer BS. The second optical pattern OP2 may be set using a printing process. In an exemplary embodiment, for example, the second optical pattern OP2 may be formed on the first optical pattern OP1 using the inkjet machine IM. The second optical pattern OP2 printed on the first optical pattern OP1 may be cured by thermal curing or UV curing. The amount of ink discharged from the ink jet machine IM can be adjusted to control the size of the second optical pattern OP 2. The ink may comprise a base resin RN-O and scattering particles SP-O.
In an exemplary embodiment, a patterning process may not be used in forming the second optical pattern OP 2. The patterning process may include, for example, an exposure process using a mask and a development process. The printing process may be simpler than the patterning process. Accordingly, in the exemplary embodiment of the present invention, the manufacture of the second optical pattern OP2 may be simplified.
Fig. 12A to 12G illustrate cross-sectional views showing an exemplary embodiment of a method of manufacturing a portion of a backlight unit according to the present invention.
Referring to fig. 12A, a first stamp (stamp) pattern STP1 is provided on a first
The first stamp pattern STP1 may be provided using a patterning process. In an exemplary embodiment, the patterning process may include, for example, a coating process, an exposure process using a mask, and a developing process.
Referring to fig. 12B, ink may be printed on the first stamp pattern STP1 to form a second stamp pattern STP 2. Each of the second stamp patterns STP2 may have an outer surface with a curvature. The first mold substrate MBS1, the first stamp pattern STP1, and the second stamp pattern STP2 may be collectively referred to as a mold substrate.
Referring to fig. 12C, an initiation layer BFM is disposed on second mold substrate MBS 2. A mold substrate is placed on the initiation layer BFM. The initiation layer BFM is then cured.
Referring to fig. 12D, when the first mold substrate MBS1, the first stamp pattern STP1, and the second stamp pattern STP2 are separated from the second mold substrate MBS2, the initiation layer BFM may be patterned to form the mold SM.
Referring to fig. 12E, an initiation layer PML is disposed on one surface of the light guide plate LGP. The initiation layer PML may be provided by a coating process.
Referring to fig. 12F, a mold SM is placed on the initial layer PML, and then the initial layer PML is first cured.
Referring to fig. 12G, the mold SM is separated from the initial layer PML, and then a second curing is performed to form the first and second optical patterns OP1 and OP2 a.
According to the above discussion, the first optical pattern may have a quadrangular shape, and the second optical pattern may be disposed under the first optical pattern. The light incident on the first optical pattern may be directed from the light incident part to the light output part, and the light incident on the second optical pattern may be directed to the display panel. Therefore, it may be possible to reduce the convergence of light on a portion adjacent to the light incident portion, thereby improving luminance uniformity.
The second optical pattern may be provided by an inkjet process performed on the first optical pattern, or may be provided using a mold obtained by using a stamp pattern provided by the inkjet process. The second optical pattern is formed using an inkjet process instead of the photolithography process, so that the fabrication of the second optical pattern may be simplified.
Although exemplary embodiments have been described with reference to a number of illustrative examples, those of ordinary skill in the art will understand that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as set forth in the following claims. Therefore, the technical scope of the present invention is not limited by the above-described exemplary embodiments and examples, but is limited by the appended claims.
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