阅读说明：本技术 显示装置 (Display device ) 是由 齐藤之人 山田直良 于 2018-05-25 设计创作，主要内容包括：一种显示装置,其设为如下：具备图像显示面板和视角切换元件,视角切换元件具备：对置配置的第1直线起偏器及第2直线起偏器；以及层叠配置于这些直线起偏器之间的视角控制单元及光学补偿片,直线起偏器以使彼此的吸收轴或反射轴平行或正交的方式配置,视角控制单元由单畴垂直取向液晶单元构成,光学补偿片的面内快轴与第1直线起偏器的吸收轴或反射轴所成的角度为30°～60°,视角控制单元的垂直取向液晶的预倾方位为与第1直线起偏器的吸收轴或反射轴呈角度30°～60°的方位。(A display device is provided with: the image display device includes an image display panel and a viewing angle switching element, and the viewing angle switching element includes: a1 st linear polarizer and a2 nd linear polarizer arranged in opposition to each other; and a viewing angle control unit and an optical compensation sheet which are stacked between the linear polarizers, wherein the linear polarizers are arranged so that absorption axes or reflection axes thereof are parallel or orthogonal to each other, the viewing angle control unit is composed of a single-domain vertical alignment liquid crystal cell, an angle formed by an in-plane fast axis of the optical compensation sheet and the absorption axis or the reflection axis of the 1 st linear polarizer is 30 DEG to 60 DEG, and a pretilt azimuth of the vertical alignment liquid crystal of the viewing angle control unit is an azimuth of 30 DEG to 60 DEG with respect to the absorption axis or the reflection axis of the 1 st linear polarizer.)

1. A display device is provided with:

an image display panel; and a viewing angle switching element disposed on one surface of the image display panel,

the viewing angle switching element includes: a1 st linear polarizer and a2 nd linear polarizer arranged in opposition to each other; and a viewing angle control unit and an optical compensation sheet laminated and disposed between the 1 st linear polarizer and the 2 nd linear polarizer,

the 1 st linear polarizer and the 2 nd linear polarizer are arranged so that their absorption axes or reflection axes are parallel or orthogonal to each other,

the viewing angle control unit is composed of a single domain vertical alignment liquid crystal cell that tilts the vertical alignment liquid crystal in one direction by application of a voltage,

the angle formed by the in-plane fast axis of the optical compensation sheet and the absorption axis or the reflection axis of the 1 st linear polarizer is 30-60 degrees,

the pretilt azimuth of the vertical orientation liquid crystal of the visual angle control unit is an azimuth which forms an angle of 30-60 degrees with the absorption axis or the reflection axis of the 1 st linear polarizer.

2. The display device according to claim 1,

in the viewing angle switching element, in the case of the viewing angle switching element,

said absorption or reflection axes of said 1 st and 2 nd linear polarizers are orthogonal to each other,

among 2 azimuths present on the in-plane fast axis of the optical compensation sheet, when the retardation is compared at a polar angle inclined by 45 °, an azimuth whose absolute value is small is the same as the pretilt azimuth of the vertically aligned liquid crystal of the viewing angle control unit.

3. The display device according to claim 1,

in the viewing angle switching element, in the case of the viewing angle switching element,

the absorption axis or reflection axis of the 1 st linear polarizer and the 2 nd linear polarizer are parallel to each other,

among 2 azimuths existing on the in-plane fast axis of the optical compensation sheet, an azimuths having a small absolute value when comparing retardations at a polar angle tilt of 45 ° is an azimuths that makes 90 ° with the pretilt azimuths of the vertically aligned liquid crystals of the viewing angle control unit with the absorption axis or reflection axis in between.

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

the optical compensation sheet comprises: and a discotic liquid crystal layer in which the angle formed by the discotic plane on which the discotic liquid crystalline molecules are immobilized and the sheet film surface increases from one film surface to the other film surface.

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

the angle formed by the in-plane fast axis of the optical compensation sheet and the absorption axis or the reflection axis of the 1 st linear polarizer is 45 degrees,

the pretilt azimuth of the vertical alignment liquid crystal of the visual angle control unit is an azimuth forming an angle of 45 degrees with the absorption axis or the reflection axis of the 1 st linear polarizer.

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

the image display panel includes: a liquid crystal cell for display; and 2 linear polarizers disposed opposite to each other with the display liquid crystal cell interposed therebetween,

and 1 of the 2 linear polarizers is also used as the 1 st linear polarizer of the visual angle switching element.

Technical Field

The present invention relates to a display device such as a liquid crystal display device or an organic electroluminescence display device, and more particularly to a display device capable of controlling a viewing angle.

Background

Electronic devices for Personal use, such as tablet PCs (Personal computers), notebook PCs, and mobile phones such as smart phones, are required to be prevented from being peeped by surrounding third persons. Therefore, in these electronic devices, the viewing angle of the screen is narrowed so as not to be peeped by the surrounding third parties. In addition, in information displays for public use, displays mounted on vehicles, electric trains, airplanes, industrial displays for medical and industrial facilities, and the like, there are increasing demands for increasing the viewing angle in a certain direction and narrowing the viewing angle in a certain direction.

As a method of narrowing the viewing angle of a screen, a method of attaching a film (louver film) or the like on which black stripes are formed to the screen is known.

However, in this method, the angle of view of the screen is fixed to a state in which the angle of view is narrow. Therefore, for example, in a case where a screen needs to be viewed also from an oblique direction, such as a case where a plurality of persons view the screen, visibility from an oblique direction is deteriorated, and usability of the electronic device is deteriorated.

In order to solve such problems, various display devices have been proposed which switch between displaying at a wide viewing angle and displaying at a narrow viewing angle in an electronic apparatus such as a tablet PC or a notebook PC in order to achieve safety such as prevention of side-looking and sufficient visibility when viewed from the side as necessary.

For example, japanese patent application laid-open No. 2007-178979 (hereinafter, referred to as patent document 1) discloses a liquid crystal display device including: a1 st substrate having gate lines and data lines corresponding to R (red), G (green), B (blue), and W (white) sub-pixels; a thin film transistor disposed at an intersection of the gate line and the data line; a plate-type 1 st common electrode provided in the sub-pixels R, G, B and W; a pixel electrode connected to the thin film transistor and insulated from the 1 st common electrode and having a plurality of slits; a2 nd substrate bonded to the 1 st substrate in a manner facing each other and including a liquid crystal layer in a space between the 1 st substrate and the substrate; and a2 nd common electrode of a plate type formed on the 2 nd substrate in a manner corresponding to the W sub-pixel.

In this liquid crystal display device, for the W sub-pixel, when wide viewing angle display is performed, the viewing angle is expanded by FFS (fringe field switching) mode driving and also the W luminance is compensated, similarly to the adjacent sub-pixels of R, G and B, and when narrow viewing angle display is performed, the viewing angle can be reduced by ECB (Electrically Controlled Birefringence) mode driving which forms a vertical electric field different from the adjacent sub-pixels of R, G and B.

Further, japanese patent application laid-open No. 2004-: a screen, the viewing angle being limited in one dimension; and an image display switching mechanism that switches between a personal view mode in which an upright direction of an image displayed on the screen is substantially orthogonal to a direction in which the angle of view is restricted, and a multiple view mode in which the upright direction of the image coincides with the direction in which the angle of view is restricted.

That is, in this display device, it is possible to restrict the viewing angle of the screen in one dimension by the microprism sheet or the like, and to switch between the wide viewing angle display and the narrow viewing angle display by whether or not the image is rotated by 90 ° so that the upper and lower surfaces of the image coincide in the restriction direction of the viewing angle.

Disclosure of Invention

Technical problem to be solved by the invention

When these display devices are used, switching between wide-angle display and narrow-angle display allows both visual recognition of display in a state where a third person is prevented from peeping from the side and appropriate recognition of display by a plurality of persons to be achieved by 1 display device.

However, in the display device of patent document 1 or patent document 2, the display of the wide viewing angle and the display of the narrow viewing angle can be switched only in 2 directions, for example, the left and right directions. That is, in the conventional method, it is difficult to obtain switching of the viewing angle only in one direction with a simple configuration.

The present invention has been made to solve the problems of the conventional techniques, and an object of the present invention is to provide a display device which can switch between wide viewing angle display and narrow viewing angle display in which the viewing angle is restricted only in a certain direction with a simple configuration.

Means for solving the technical problem

The display device of the present invention is a display device including: an image display panel; and a viewing angle switching element disposed on one surface of the image display panel,

the viewing angle switching element includes: a1 st linear polarizer and a2 nd linear polarizer arranged in opposition to each other; and a viewing angle control unit and an optical compensation sheet, which are stacked between the 1 st linear polarizer and the 2 nd linear polarizer,

the 1 st and 2 nd linear polarizers are arranged so that their absorption axes or reflection axes are parallel or orthogonal to each other,

the viewing angle control unit is composed of a single domain vertically aligned liquid crystal cell in which vertically aligned liquid crystal is tilted in one direction by application of a voltage,

the angle formed by the in-plane fast axis of the optical compensation sheet and the absorption axis or the reflection axis of the 1 st linear polarizer is 30-60 degrees,

the pretilt azimuth of the vertical orientation liquid crystal of the visual angle control unit is an azimuth which forms an angle of 30-60 degrees with the absorption axis or the reflection axis of the 1 st linear polarizer.

In the above description, the "absorption axis or reflection axis" refers to an absorption axis when the linear polarizer is an absorption type polarizer and a reflection axis when the linear polarizer is a reflection type polarizer.

The display device of the present invention can be configured as follows: in the viewing angle switching element, the absorption axes or the reflection axes of the 1 st linear polarizer and the 2 nd linear polarizer are orthogonal to each other, and among 2 azimuths existing on the in-plane fast axis of the optical compensation sheet, when the retardation is compared at a polar angle of 45 °, the azimuths having small absolute values are the same as the pretilt azimuths of the vertically aligned liquid crystal of the viewing angle control unit.

The display device of the present invention can be configured as follows: in the viewing angle switching element, the absorption axes or the reflection axes of the 1 st linear polarizer and the 2 nd linear polarizer are parallel to each other, and among 2 azimuths existing on the in-plane fast axis of the optical compensation sheet, when the retardation is compared at a polar angle of 45 °, the azimuths having small absolute values are azimuths 90 ° from the pretilt azimuths of the vertically aligned liquid crystal of the viewing angle control unit via the absorption axes or the reflection axes.

In the display device of the present invention, it is preferable that: the optical compensation sheet comprises: and a discotic liquid crystal layer in which the angle formed by the discotic plane of the discotic liquid crystalline molecules and the sheet film surface increases from one film surface to the other film surface and which is formed by hybrid orientation immobilization.

In the display device of the present invention, it is preferable that: the angle formed by the in-plane fast axis of the optical compensation sheet and the absorption axis or the reflection axis of the 1 st linear polarizer is 45 degrees, and the pretilt azimuth of the vertical alignment liquid crystal of the visual angle control unit is the azimuth forming an angle of 45 degrees with the absorption axis or the reflection axis of the 1 st linear polarizer.

The display device of the present invention is preferably as follows: the image display panel includes: a liquid crystal cell for display; and 2 linear polarizers arranged opposite to each other with the display liquid crystal cell interposed therebetween,

1 of the 2 linear polarizers is also used as the 1 st linear polarizer of the visual angle switching element.

Effects of the invention

A display device of the present invention includes: an image display panel; and a viewing angle switching element disposed on one surface of the image display panel, the viewing angle switching element including: a1 st linear polarizer and a2 nd linear polarizer arranged in opposition to each other; and a viewing angle control unit and an optical compensation sheet, which are stacked between the 1 st linear polarizer and the 2 nd linear polarizer, wherein the 1 st linear polarizer and the 2 nd linear polarizer are disposed so that absorption axes or reflection axes thereof are parallel or orthogonal to each other, the viewing angle control unit is composed of a single-domain vertical alignment liquid crystal cell in which vertical alignment liquid crystal is inclined in one direction by application of a voltage, an angle formed by an in-plane fast axis of the optical compensation sheet and the absorption axis or reflection axis of the 1 st linear polarizer is 30 to 60 °, and a pretilt azimuth of the vertical alignment liquid crystal of the viewing angle control unit is an azimuth of 30 to 60 ° with respect to the absorption axis or reflection axis of the 1 st linear polarizer, so that it is possible to switch between display of a wide viewing angle and display of a narrow viewing angle in which the viewing angle is limited, only in one direction with a simple configuration.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a display device according to an embodiment of the present invention.

Fig. 2 is a perspective view showing a schematic configuration of the display device 101 of configuration example 1.

Fig. 3 is a perspective view showing a schematic configuration of the display device 201 of configuration example 2.

Fig. 4 is a diagram showing a schematic configuration of a display device according to a design modification.

Fig. 5 is a diagram showing a schematic configuration of a display device according to another design modification.

Detailed Description

Hereinafter, embodiments of the display device of the present invention will be described with reference to the drawings.

In the present specification, the numerical range expressed by the term "to" means a range in which the numerical values described before and after the term "to" are included as the lower limit value and the upper limit value. In addition, regarding the angle, "orthogonal" and "parallel" mean a range of a strict angle ± 10 °.

The display device 1 of embodiment 1 includes: an image display panel 10; and a viewing angle switching element 20 disposed on one main surface of the image display panel.

In the present embodiment, the image display panel 10 is a Liquid Crystal Display (LCD) and includes 2 linear polarizers 12 and 22 having absorption axes or reflection axes orthogonal to each other, and a display liquid crystal cell 14 disposed between 1 linear polarizer 12 and 22. The viewing angle switching element 20 includes 2 linear polarizers 22 and 28 having absorption axes or reflection axes orthogonal to each other, and a viewing angle control unit 24 and an optical compensation sheet 26 stacked between the 2 linear polarizers 22 and 28. In the present embodiment, the linear polarizer 22 disposed on the viewing side of the image display panel 10 also serves as the 1 st linear polarizer of the viewing angle switching element 20. In the following description of the viewing angle switching element 20, the linear polarizer 22 on the viewing side of the image display panel 10 is referred to as the 1 st linear polarizer 22. In addition, the other linear polarizer 28 of the viewing angle switching element 20 is referred to as a2 nd linear polarizer 28.

Hereinafter, a case where the linear polarizer is an absorption polarizer will be described. When a reflective polarizer is used as the linear polarizer, the absorption axis may be replaced by the reflection axis, and the same effects as those in the case of the absorption polarizer described below are exhibited.

Here, the linear polarizer 22 is generally provided with a polarizing plate having a protective film on one or both surfaces thereof. Hereinafter, the linear polarizer 22 may be replaced with a polarizing plate.

The viewing angle switching element 20 emits light from the display liquid crystal cell 14 from the 1 st linear polarizer 22 as linearly polarized light, and gives a polarization change due to birefringence to the emitted linearly polarized light. When the polarized light reaches the 2 nd linear polarizer 28, the angle of view is wide for transmitting light when the polarized light is parallel to the transmission axis of the 2 nd linear polarizer 28, and is narrow for not transmitting light when the polarized light is vertical. The viewing angle switching element 20 has a function of applying a change in polarization of polarized light perpendicular to the transmission axis of the 2 nd linear polarizer 28 only in one direction and applying a change in polarization of polarized light parallel to the transmission axis of the 2 nd linear polarizer 28 in the other directions than the one direction by setting the applied voltage in the viewing angle control means from an initial value (off state) to a predetermined value (on state). Here, the initial value of the applied voltage is a voltage value when the viewing angle is uniform to a wide viewing angle by the viewing angle control unit 24, and is not limited to 0V.

The viewing angle control unit 24 is composed of a single-domain vertically aligned liquid crystal cell in which vertically aligned liquid crystal is tilted to one direction by application of a voltage and has negative dielectric constant anisotropy. In the viewing angle control unit 24, when no voltage is applied, the rod-like liquid crystal molecules are aligned substantially vertically (for example, aligned at a pretilt angle of 89 ° in the later-described embodiment), and when a voltage is applied, the long axes of the liquid crystal molecules are uniformly inclined in the direction of inclination of the pretilt angle (a specific one direction). Thus, when the applied voltage is an initial value, the same change or no change is generated in all directions in the plane with respect to the polarized light of the light passing through the viewing angle control unit 24. When the applied voltage is changed from the initial value, a change in polarization can be generated only in a specific direction with respect to the polarization of light passing through the viewing angle control unit 24, the direction being different from the other directions. In this specification, an in-plane azimuth in a direction in which liquid crystal molecules are uniformly tilted is referred to as a pretilt azimuth.

The absorption axis of the linear polarizer on the surface of the conventional LCD is generally in the left-right direction (azimuth angle 0-180) or the up-down direction (azimuth angle 90-270) of the picture when the picture is viewed from the front. At this time, if the pretilt azimuth of the viewing angle control means 24 coincides with the left-right direction, the direction in which the liquid crystal molecules tilt due to the voltage application is parallel to or orthogonal to the absorption axis of the linear polarizer, and therefore the polarization of the light passing therethrough does not change. On the other hand, in one embodiment of the present invention, the pretilt azimuth of the viewing angle control unit 24 is configured to be an azimuth making an angle of 45 ° with the absorption axis of the 1 st linear polarizer. However, since the difference between the polarization change in the predetermined direction and the polarization change in the other direction is insufficient only by the viewing angle control means 24, the optical compensation sheet 26 including the optically anisotropic layer having asymmetric optical anisotropy in the azimuth direction is disposed so that the angle formed by the in-plane fast axis and the absorption axis of the 1 st linear polarizer 22 becomes substantially 45 °. This makes it possible to sufficiently change the polarization in a predetermined direction from that in other directions, and to switch the viewing angle only in the predetermined direction.

In addition, in the case of comparing the retardation at a polar angle of 45 ° among 2 azimuths present on the in-plane fast axis of the optical compensation sheet 26, an azimuths having a small absolute value (hereinafter, referred to as R azimuths) is preferably the same as the pretilt azimuths or azimuths having an angle of 90 ° with the pretilt azimuths with the absorption axis of the 1 st linear polarizer 22 therebetween.

In the viewing angle switching element 20, when the absorption axes of the 1 st linear polarizer 22 and the 2 nd linear polarizer 28 are orthogonal, the viewing angle switching element 20 generates a polarization change that changes the phase by 90 ° in all directions with respect to the light passing through the viewing angle control unit 24 and the optical compensation sheet 26 when the applied voltage to the viewing angle control unit 24 is an initial value (off state). On the other hand, when the voltage applied to the viewing angle control unit 24 is a predetermined value (on state), the polarization of the passing light hardly changes in a predetermined direction, but changes in the polarization by 90 ° in the other directions.

In the viewing angle switching element 26, when the absorption axes of the 1 st linear polarizer 22 and the 2 nd linear polarizer 28 are parallel, the viewing angle switching element 20 does not change the phase in all directions with respect to the light passing through the viewing angle control unit 24 and the optical compensation sheet 26 when the applied voltage to the viewing angle control unit 24 is an initial value (off state). On the other hand, when the voltage applied to the viewing angle control unit 24 is a predetermined value (on state), a polarization change that changes the phase by 90 ° occurs in a predetermined direction with respect to the light that passes through, and the phase is not changed in the other directions.

With the above-described viewing angle switching element 26, the display device 1 is capable of performing image display in which the viewing angle is changed from a wide viewing angle to a narrow viewing angle only in one direction by on/off control of the viewing angle switching element.

A more specific configuration example of the display device according to embodiment 1 will be described below with reference to fig. 2 and 3. In fig. 2 and 3, the same components as those of the display device according to embodiment 1 are denoted by reference numerals with 100 added to the reference numerals used in fig. 1 in configuration example 1 shown in fig. 2, and reference numerals with 200 added to the reference numerals used in configuration example 2 shown in fig. 3.

[ structural example 1]

Fig. 2 is a perspective view showing a schematic configuration of the display device 101 of configuration example 1.

In the display device 101 of FIG. 2, the 1 st linear polarizer 122 and the 2 nd linear polarizer 128 are arranged so that their absorption axes A1, A2 are orthogonal to each other. In this example, the right direction in the left-right direction in the drawing is defined as azimuth 0 °, the left direction is defined as azimuth 180 °, and the absorption axis a1 of the 1 st linear polarizer 122 coincides with the left-right direction. At this time, the absorption axis a1 is oriented at 0 ° and 180 °.

The pretilt direction of the viewing angle controlling unit 124 is 225 °, and is an angle of 45 ° with respect to the absorption axis a1 (direction 180 °). The R-orientation of the optical compensation sheet 126 is also 225 °, and is an orientation forming an angle of 45 ° with the absorption axis a1 (orientation 180 °).

In the present configuration example 1, the angle of view on the left direction (azimuth 180 °) side in the figure can be switched from the wide field of view to the narrow field of view. The wide view field state is set to the off state, and the narrow view field state is set to the on state.

In this configuration, when a large voltage (for example, 5V) is applied to the viewing angle control means 124 to display white on the image display panel 110, the liquid crystal molecules horizontally tilt in the pretilt azimuth to cause in-plane retardation, and therefore the incident polarized light changes to be in a white state in the front and all viewing angle directions, and becomes in an "off" state as viewing angle control. When the voltage is lowered from this state (for example, 3.4V), the tilt angle of the liquid crystal molecules becomes small (the liquid crystal molecules are in a state of being tilted horizontally and standing up), and the long axis direction of the liquid crystal molecules is tilted obliquely in the pretilt azimuth, so that the retardation in the pretilt azimuth is smaller than that in other azimuths. The transmittance is lowered in the direction of small retardation than in the other directions to be in a black state, and the state is turned on as viewing angle control. In configuration example 1, the pretilt azimuth P of the viewing angle control means is set to 225 °, and therefore the transmittance change at the azimuth 225 ° is the largest, but in order to increase the transmittance change in the screen left direction (azimuth 180 ° direction), the optical anisotropic layer (optical compensation sheet 126) having retardation asymmetry in the axial direction including the R azimuth is disposed so that the R azimuth becomes 225 ° to adjust the oblique retardation.

[ structural example 2]

Fig. 3 is a perspective view showing a schematic configuration of the display device 201 of configuration example 2.

In the display device 201 of FIG. 3, the 1 st and 2 nd linear polarizers 122, 128 are arranged with their absorption axes A1, A2 parallel to each other. In this example, the right direction in the left-right direction in the drawing is also defined as azimuth 0 °, the left direction is defined as azimuth 180 °, and the absorption axis a1 of the 1 st linear polarizer 122 coincides with the left-right direction. At this time, the absorption axis a1 is oriented at 0 ° and 180 °.

The pretilt angle of the viewing angle controlling unit 224 is 45 °, which is an angle of 45 ° to the absorption axis a1 (azimuth 0 °). The optical compensation sheet 226 has an R orientation of 315 ° and an orientation forming an angle of 45 ° with the absorption axis a1 (orientation 0 °).

In configuration example 2, the angle of view on the left direction (azimuth 180 °) side in the figure can be switched from a wide field of view (off state) to a narrow field of view (on state).

In this configuration, when the image display panel 110 is caused to display white, the liquid crystal molecules are aligned substantially vertically when no voltage (0V) is applied to the viewing angle control means 224, and therefore no retardation occurs in the front surface and the retardation in the oblique direction is small, and therefore the image display panel is caused to be in a white state in the front surface and all viewing angle directions and is caused to be in an "off" state as viewing angle control. When the voltage is increased from this state (for example, 3.0V), the long axis direction of the liquid crystal molecules falls in the pretilt azimuth to be in a state inclined obliquely, and therefore the retardation is larger in the azimuth opposite to the pretilt azimuth than in the other azimuths. The transmittance is lowered in the direction of large retardation than in the other directions to be in a black state, and the state is turned on as viewing angle control. In configuration example 2, the pretilt azimuth P of the viewing angle control means is set to 45 °, and therefore the transmittance change at the azimuth 225 ° is the largest, but in order to increase the transmittance change in the screen left direction (azimuth 180 ° direction), the optical anisotropic layer (optical compensation sheet 226) having asymmetric optical anisotropy in the azimuth direction is arranged so that the R azimuth thereof becomes 315 °, and the oblique retardation is adjusted. Unlike structure example 1, structure example 2 shows that the pretilt azimuth of the display liquid crystal cell is orthogonal to the R azimuth of the optically anisotropic layer. The difference between the two structural examples is as follows: while the 1 st and 2 nd linear polarizers are disposed so that their absorption axes are orthogonal to each other in structural example 1, the 1 st and 2 nd linear polarizers are disposed so that their absorption axes are parallel to each other in structural example 2.

In the above-described embodiment, the angle formed by the in-plane fast axis of the optical compensation sheet and the absorption axis of the 1 st linear polarizer was set to 45 °, and the pretilt azimuth of the vertically aligned liquid crystal of the viewing angle control means was set to an azimuth of 45 ° to the absorption axis of the 1 st linear polarizer, but these angles may be appropriately set in the range of 30 ° to 60 °. When the angle of view in the left direction (azimuth 180 °) of the screen is controlled as in the above configuration examples 1 and 2, etc., 45 ° is suitable as the angle, but in the angle of view control from a direction completely deviated from the lateral direction such as azimuth 160 °, the angle of deviation from 45 ° is suitable, and therefore, the adjustment may be performed in accordance with the desired angle of view control azimuth.

In the above-described embodiment, the configuration in which the viewing angle switching element is provided with the viewing angle control means on the 1 st linear polarizer side and the optical compensation sheet on the 2 nd linear polarizer side has been described, but the arrangement of the viewing angle control means 24 and the optical compensation sheet 26 may be reversed. That is, as shown in fig. 4, the display device 2 may be provided with the optical compensation sheet 26 on the 1 st linear polarizer 22 side and the viewing angle control means on the 2 nd linear polarizer 28 side.

In the above embodiment, the case where the image display panel is a liquid crystal panel was described, but the image display panel is not limited to the liquid crystal panel and may be an OLED (Organic Light Emitting Diode) or a printed matter. When the image display panel is an OLED or a printed matter, since the light exit surface does not include the linear polarizer, the viewing angle switching element 20 may include the 1 st linear polarizer independently of the image display panel. That is, as shown in fig. 5, the display device according to the embodiment of the present invention may be a display device 3 including a viewing angle switching device 20 having a1 st linear polarizer, a viewing angle control unit 24, an optical compensation sheet, and a2 nd linear polarizer on the light emission surface side of the OLED 110.

In the above embodiment, the display device having the configuration in which the viewing angle switching element 20 is provided on the viewing side of the display panel has been described, but when the image display panel is an LCD, the viewing angle switching element may be provided on the opposite side to the viewing side of the image display panel, that is, on the LCD backlight side. The same effects as those of the above-described configuration can be obtained regardless of which surface side of the display panel is provided with the viewing angle switching element 20.

In the above-described embodiment, the 1 st and 2 nd linear polarizers are both absorption polarizers, but one or both of the 1 st and 2 nd linear polarizers may be reflection polarizers, or one may be absorption polarizers and the other may be reflection polarizers. Further, at least one of the linear polarizers may be a laminated structure of an absorption polarizer and a reflection polarizer. In recycling light, a reflective polarizer is preferably used. When the image display panel is an LCD, the viewing angle switching element may be disposed on the anti-visual recognition side of the image display panel, and the 2 nd linear polarizer may be a reflective polarizer, and the 1 st linear polarizer may be a laminated layer of a reflective polarizer and an absorbing polarizer. With such a configuration, both the backlight cycle and the display quality (contrast, etc.) of the image display panel can be achieved.

The optical compensation sheet used in one embodiment of the present invention can be preferably an optical compensation sheet provided with a discotic liquid crystal layer in which discotic liquid crystalline molecules are immobilized by hybrid alignment in which the angle formed by the discotic plane and the sheet film surface increases from one film surface to the other film surface, for example. Specifically, the optical compensation sheet described in Japanese patent application laid-open Nos. 2004-354962 and 2005-206638 can be preferably used.

The optical compensation sheet having an optically anisotropic layer is preferably the optical compensation sheet described in jp 2004-354962 a, but as long as the R-direction is the same direction, the effects of one embodiment of the present invention can be obtained even when a plurality of layers (for example, 2 sheets) are stacked.

Further, the optical compensation sheet used in jp 2004-354962 a includes a support and an optically anisotropic layer containing a liquid crystal material, but as long as the R-direction is the same direction, the surface of the support may be the viewing angle control unit side or the display liquid crystal unit side.

As the linear polarizer used in one embodiment of the present invention, a known linear polarizer can be used, and for example, a PVA (polyvinyl alcohol) iodine polarizer can be used, but the present invention is not limited thereto.