Optical element and display device

Abstract

To provide an optical element and a display device in which a viewing angle can be controlled suitably with a simple structure.SOLUTION: An optical element includes a first polarization plate with a first absorption axis, a second polarization plate facing the first polarization plate and having a second absorption axis, and a first viewing angle control panel disposed between the first polarization plate and the second polarization plate. The first viewing angle control panel includes a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, and a plurality of electrodes provided on at least one of the first substrate and the second substrate and generating a lateral electric field in a predetermined direction. The liquid crystal layer includes a liquid crystal molecule whose dielectric anisotropy is positive, and the liquid crystal molecule is subjected to hybrid alignment in a state where the lateral electric field is not generated.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an optical element and a display device. [Background technology]

[0002] Display devices equipped with optical elements that control the viewing angle are known (see, for example, Patent Document 1). The display device of Patent Document 1 includes an optical element (described as a viewing angle control liquid crystal cell in Patent Document 1) that ensures a wide viewing angle of the display panel when the voltage is applied and suppresses brightness in the horizontal direction when the voltage is turned off. The optical element has a pair of light-transmitting substrates and a liquid crystal layer disposed between the pair of light-transmitting substrates and configured with liquid crystal molecules in a hybrid orientation. The liquid crystal molecules of the liquid crystal layer are made of a material with negative dielectric anisotropy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-275342 Summary of the Invention [Problem to be solved by the invention]

[0004] Liquid crystal layers with liquid crystal molecules that have a negative dielectric anisotropy have higher viscosity than liquid crystal layers with liquid crystal molecules that have a positive dielectric anisotropy, which can lead to a slower response speed when switching voltage on and off. On the other hand, liquid crystal layers with liquid crystal molecules that have a positive dielectric anisotropy can have a lower viewing angle when voltage is applied, requiring a viewing angle compensation film such as a C-plate. For this reason, there is a demand for optical elements that use liquid crystal layers with liquid crystal molecules that have a positive dielectric anisotropy and can control the viewing angle with a simpler configuration.

[0005] An object of the present invention is to provide an optical element and a display device that can effectively control the viewing angle with a simple configuration. [Means for solving the problem]

[0006] An optical element according to one embodiment of the present invention comprises a first polarizer having a first absorption axis, a second polarizer facing the first polarizer and having a second absorption axis, and a first viewing angle control panel arranged between the first polarizer and the second polarizer, wherein the first viewing angle control panel comprises a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, and a plurality of electrodes provided on at least one of the first substrate and the second substrate to generate a transverse electric field in a predetermined direction, wherein the liquid crystal layer comprises liquid crystal molecules having positive dielectric anisotropy, and the liquid crystal molecules are hybrid-oriented when the transverse electric field is not generated.

[0007] A display device according to one aspect of the present invention includes the optical element described above, a display panel laminated with the optical element, and an illumination device that irradiates the optical element with light. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a display device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating an example of the configuration of the display panel according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view schematically illustrating an example of the configuration of the optical element according to the first embodiment. [Figure 4] FIG. 4 is a plan view showing the first electrode and the second electrode of the first viewing angle control panel. [Figure 5] FIG. 5 is an explanatory diagram for explaining the relationship between the absorption axis direction of each polarizer and the alignment direction of the liquid crystal layer of the first view angle control panel in the display device according to the first embodiment. [Figure 6] FIG. 6 is a graph showing the relationship between brightness and polar angle for the display devices according to Examples 1 and 2. In FIG. [Figure 7] FIG. 7 is a diagram showing the viewing angle dependency of brightness in the first state of the display device according to the first embodiment. [Figure 8]FIG. 8 is a diagram showing the viewing angle dependency of brightness in the second state of the display device according to Example 1. As shown in FIG. [Figure 9] FIG. 9 is a diagram showing the viewing angle dependency of brightness in the second state of the display device according to the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view schematically showing an example of the configuration of an optical element according to a first modified example. [Figure 11] FIG. 11 is a cross-sectional view schematically showing an example of the configuration of an optical element according to the second modified example. [Figure 12] FIG. 12 is a cross-sectional view schematically showing a display device according to the second embodiment. [Figure 13] FIG. 13 is an explanatory diagram for explaining the relationship between the absorption axis direction of each polarizer and the alignment direction of the liquid crystal layer of the first view angle control panel in the display device according to the second embodiment. [Figure 14] FIG. 14 is a cross-sectional view schematically showing a display device according to a third modification of the second embodiment. [Figure 15] FIG. 15 is an explanatory diagram for explaining the relationship between the absorption axis direction of each polarizer and the alignment direction of the liquid crystal layer of the first viewing angle control panel in a display device according to a third modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present disclosure is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the components described below can be combined as appropriate. Note that the disclosure is merely an example, and any appropriate modifications that a person skilled in the art can easily make while maintaining the gist of the present disclosure are naturally included within the scope of the present disclosure. Furthermore, for clarity of explanation, the drawings may schematically depict the width, thickness, shape, etc. of each part compared to the actual embodiment. However, these are merely examples and are not intended to limit the interpretation of the present disclosure. Furthermore, in this disclosure and each figure, elements similar to those previously described with reference to the preceding figures may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0010] In this specification and claims, when expressing an aspect of placing another structure on top of a certain structure, the term "on top" is used, unless otherwise specified, to include both a case in which another structure is placed directly on top of a certain structure so as to be in contact with the certain structure, and a case in which another structure is placed above a certain structure via yet another structure.

[0011] (First embodiment) Fig. 1 is a cross-sectional view schematically showing a display device according to embodiment 1. As shown in Fig. 1, the display device 100 includes an optical element 10, a display panel 50, a third polarizing plate 23, an illumination device 60, and a control circuit 70.

[0012] The optical element 10 is disposed between the lighting device 60 and the display panel 50 in a direction (third direction Dz) perpendicular to the display surface of the display panel 50. The optical element 10 has a first polarizer 21, a second polarizer 22, and a first viewing angle control panel 20 disposed between the first polarizer 21 and the second polarizer 22. The optical element 10 is stacked in the third direction Dz, from the lighting device 60 toward the display panel 50, with the second polarizer 22, the first viewing angle control panel 20, and the first polarizer 21 stacked in this order. A detailed configuration of the optical element 10 will be described later with reference to FIG. 3 and subsequent figures.

[0013] In the following description, the first direction Dx is a direction in a plane parallel to the surface of the optical element 10 (i.e., the surface of the first polarizing plate 21). The second direction Dy is a direction in a plane parallel to the surface of the optical element 10 and is a direction perpendicular to the first direction Dx. The second direction Dy may intersect with the first direction Dx without being perpendicular thereto. The third direction Dz is a direction perpendicular to the first direction Dx and the second direction Dy. The third direction Dz is a normal direction to the surface of the optical element 10. The third direction Dz can also be referred to as a normal direction to the display surface of the display panel 50. Furthermore, the term "planar view" refers to the positional relationship when viewed from a direction perpendicular to the surface of the optical element 10.

[0014] In the following description, the direction from the first polarizing plate 21 to the third polarizing plate 23 in the direction perpendicular to the surface of the optical element 10 will be referred to as the "upper side" or simply "upper." The direction from the third polarizing plate 23 to the first polarizing plate 21 will be referred to as the "lower side" or simply "lower."

[0015] The display panel 50 is a liquid crystal display panel including a liquid crystal layer LC (see FIG. 2) as a display functional layer. The display panel 50 is stacked opposite the optical element 10. More specifically, the display panel 50 faces the first viewing angle control panel 20 with a second polarizing plate 22 sandwiched therebetween. In addition, a third polarizing plate 23 is provided on the display surface side of the display panel 50.

[0016] The illumination device 60 is a backlight unit. The illumination device 60 may have any configuration, but for example, an edge-lit backlight or a direct-type backlight is applicable. The edge-lit backlight has a light source such as an LED (Light Emitting Diode) and a light guide plate, with the LED provided at the edge of the light guide plate. The direct-type backlight has the LED provided directly below the diffusion plate.

[0017] The control circuit 70 is electrically connected to each of the display panel 50, the first viewing angle control panel 20, and the lighting device 60, and is configured to control the driving of each of the display panel 50, the first viewing angle control panel 20, and the lighting device 60.

[0018] In the display device 100 of this embodiment, the lighting device 60 emits diffused light toward the optical element 10. The first viewing angle control panel 20 of the optical element 10 is a viewing angle control element that adjusts the viewing angle dependency of light incident from the lighting device 60 and suppresses transmission of light in a specific direction. More specifically, the first viewing angle control panel 20, together with the first polarizer 21 and the second polarizer 22, switches between a first state in which transmission of light incident from the lighting device 60 is suppressed in a specific direction, and a second state in which the light incident from the lighting device 60 is output as diffused light. That is, the optical element 10 outputs light with higher directionality in the first state compared to the second state.

[0019] Light transmitted through the optical element 10 is incident on the display panel 50. In the first state, the display panel 50 displays an image with reduced brightness in a specific direction. In the second state, the display panel 50 displays an image with a wider viewing angle than in the first state.

[0020] In the following description, the polar angle θ is the angle with respect to a direction parallel to the third direction Dz. The polar angle θ in the direction parallel to the third direction Dz is set to 0°. In addition, in FIG. 1, the polar angle θ on the right side of the third direction Dz (one side of the first direction Dx) may be expressed as positive (+θ), and the polar angle θ on the left side of the third direction Dz (the other side of the first direction Dx) may be expressed as negative (-θ).

[0021] Here, the layers of the display device 100, namely the first polarizer 21, the first viewing angle control panel 20, the second polarizer 22, the display panel 50, and the third polarizer 23, are bonded together by a light-transmitting adhesive layer (not shown). However, without being limited thereto, the layers of the optical element 10, the display panel 50, and the third polarizer 23 may be laminated with an air layer interposed therebetween without providing an adhesive layer therebetween.

[0022] In this embodiment, the second polarizing plate 22 of the optical element 10 is also used as a polarizing plate on the back side of the display panel 50. That is, one second polarizing plate 22 is disposed between the display panel 50 and the first viewing angle control panel 20 of the optical element 10. This makes it possible to improve the light transmittance compared to a configuration in which a polarizing plate for the display panel 50 is provided on the back side of the display panel 50 in addition to the second polarizing plate 22 of the optical element 10.

[0023] Next, the configuration of the display panel 50 will be described. FIG. 2 is a cross-sectional view that schematically shows an example of the configuration of a display panel according to the first embodiment. The display panel 50 includes, for example, an array substrate SUB1, a counter substrate SUB2, and a liquid crystal layer LC as a display function layer. The counter substrate SUB2 is disposed opposite the array substrate SUB1. The liquid crystal layer LC is sealed between the array substrate SUB1 and the counter substrate SUB2.

[0024] The array substrate SUB1 has a first insulating substrate 51, a circuit formation layer 52, a common electrode 53, an insulating film 54, a pixel electrode 55, and a lower alignment film 56. The circuit formation layer 52, the common electrode 53, the insulating film 54, the pixel electrode 55, and the lower alignment film 56 are stacked in this order on the first insulating substrate 51 in the third direction Dz.

[0025] The first insulating substrate 51 is a light-transmitting glass substrate or film substrate. The circuit formation layer 52 is a layer on which pixel circuits including a plurality of thin film transistors as switching elements and various wirings are formed. The common electrode 53 is an electrode to which a predetermined constant potential is applied. The insulating film 54 insulates the common electrode 53 from the pixel electrodes 55. The pixel electrodes 55 are provided for each pixel, and the potential of each electrode is individually controlled. The lower alignment film 56 is provided to cover the pixel electrodes 55 and the insulating film 54.

[0026] The counter substrate SUB2 has a second insulating substrate 59 and an upper alignment film 58. The upper alignment film 58 is provided on the surface of the second insulating substrate 59 facing the first insulating substrate 51. The upper alignment film 58 becomes the surface of the counter substrate SUB2 on the liquid crystal layer LC side. Although not shown in FIG. 2, the counter substrate SUB2 may be provided with a color filter or a light-shielding film as needed.

[0027] The liquid crystal layer LC modulates light passing therethrough according to the state of an electric field, and uses, for example, a liquid crystal in a transverse electric field mode such as IPS (In-Plane Switching) including FFS (Fringe Field Switching). In this embodiment, the liquid crystal layer LC is driven by a transverse electric field generated between the pixel electrodes 55 and the common electrode 53 provided on the array substrate, and the orientation of the liquid crystal molecules 57 of the liquid crystal layer LC is controlled.

[0028] However, the display panel 50 is not limited to this configuration, and may be a vertical electric field type liquid crystal display panel. In this case, the pixel electrodes are provided on the array substrate, and the common electrode is provided on the counter substrate. Vertical electric field type liquid crystal display panels include TN (Twisted Nematic), VA (Vertical Alignment), and ECB (Electrically Controlled Birefringence), in which a so-called vertical electric field is applied to the liquid crystal layer.

[0029] Next, the detailed configuration of the optical element 10 will be described. Fig. 3 is a cross-sectional view schematically showing an example of the configuration of the optical element according to the first embodiment. Fig. 4 is a plan view showing the first electrode and the second electrode of the first viewing angle control panel. Fig. 5 is an explanatory diagram for explaining the relationship between the absorption axis direction of each polarizer and the alignment direction of the liquid crystal layer of the first viewing angle control panel in the display device according to the first embodiment.

[0030] As shown in FIGS. 3 and 5, the first polarizing plate 21 and the second polarizing plate 22 are linear polarizing plates. The first polarizing plate 21 has a first absorption axis AX1 extending in a direction parallel to the second direction Dy. The second polarizing plate 22 faces the first polarizing plate 21 and has a second absorption axis AX2 extending in a direction parallel to the second direction Dy. In a plan view, the first absorption axis AX1 of the first polarizing plate 21 is parallel to the second absorption axis AX2 of the second polarizing plate 22. Although not shown, the first polarizing plate 21 has a first easy transmission axis perpendicular to the first absorption axis AX1. Furthermore, the second polarizing plate 22 has a second easy transmission axis perpendicular to the second absorption axis AX2.

[0031] The third polarizer 23 provided on the display surface side of the display panel 50 has a third absorption axis AX3 and a third easy transmission axis perpendicular to the third absorption axis. The third absorption axis AX3 and the third easy transmission axis of the third polarizer 23 are oriented in a predetermined direction in a planar view depending on the display mode of the display panel 50. In the example shown in Fig. 5, the third absorption axis AX3 of the third polarizer 23 is perpendicular to the second absorption axis AX2 of the second polarizer 22 in a planar view.

[0032] 3, the first viewing angle control panel 20 has a first substrate 11, a plurality of first electrodes 12 and a plurality of second electrodes 13, a first alignment film 14, a liquid crystal layer 15, a second alignment film 17, and a second substrate 18. A first polarizing plate 21, the first substrate 11, the plurality of first electrodes 12 and a plurality of second electrodes 13, the first alignment film 14, the liquid crystal layer 15, the second alignment film 17, the second substrate 18, and the second polarizing plate 22 are stacked in this order in the third direction Dz.

[0033] The first substrate 11 is provided on the first polarizing plate 21. The first substrate 11 is a light-transmitting insulating substrate and is made of, for example, glass or resin. The plurality of first electrodes 12 and the plurality of second electrodes 13 are provided on the upper surface of the first substrate 11, i.e., on the surface of the first substrate 11 facing the second substrate 18. The plurality of first electrodes 12 and the plurality of second electrodes 13 are made of a light-transmitting conductive material, such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide).

[0034] As shown in FIG. 4 , the plurality of first electrodes 12 and the plurality of second electrodes 13 are provided on the same surface of the first substrate 11 and are arranged in an area overlapping at least the display area AA of the display panel 50. The plurality of first electrodes 12 and the plurality of second electrodes 13 each extend in the second direction Dy and are arranged alternately at intervals in the first direction Dx. That is, they are arranged in the first direction Dx as follows: first electrode 12, second electrode 13, first electrode 12, second electrode 13, ... With this configuration, when a voltage is supplied to the plurality of first electrodes 12 and the plurality of second electrodes 13, a transverse electric field is generated between the first electrodes 12 and the second electrodes 13 in the first direction Dx.

[0035] 3, the first alignment film 14 is provided on the first substrate 11, covering the plurality of first electrodes 12 and the plurality of second electrodes 13. The first alignment film 14 is a vertical alignment film that vertically aligns liquid crystal molecules in the liquid crystal layer 15.

[0036] The second substrate 18 is disposed opposite the first substrate 11 and is disposed between the first substrate 11 and the second polarizing plate 22 in the third direction Dz. The second substrate 18 is a light-transmitting insulating substrate and is formed of, for example, glass or resin. In this embodiment, the second substrate 18 is not provided with an electrode. The second alignment film 17 is provided on the lower surface of the second substrate 18, i.e., on the surface of the second substrate 18 facing the first substrate 11. An alignment axis parallel to the first direction Dx is formed on the second alignment film 17 by a rubbing process or the like.

[0037] The liquid crystal layer 15 is provided between the first substrate 11 and the second substrate 18. More specifically, the liquid crystal layer 15 is provided between the first alignment film 14 and the second alignment film 17. The liquid crystal layer 15 has liquid crystal molecules 16 with positive dielectric anisotropy. The liquid crystal molecules 16 are rod-shaped with long axes LA, and the dielectric constant ε1 in the direction along the long axes LA of the liquid crystal molecules 16 is greater than the dielectric constant ε2 in the direction of the short axes perpendicular to the long axes LA of the liquid crystal molecules 16 (ε1>ε2).

[0038] The liquid crystal molecules 16 of the liquid crystal layer 15 are hybrid-oriented when no voltage is applied to the plurality of first electrodes 12 and the plurality of second electrodes 13, i.e., when no transverse electric field is generated. Here, hybrid orientation refers to a state in which the liquid crystal molecules 16 having a long axis LA sandwiched between a pair of substrates are oriented such that the direction of the long axis LA is parallel to the substrate on one substrate side and perpendicular to the substrate on the other substrate side.

[0039] 3, the tilt angle formed between the long axis LA of the liquid crystal molecules 16 and a direction parallel to the surface of the first substrate 11 (for example, the first direction Dx) continuously changes along the third direction Dz. In the hybrid alignment state, the tilt angle of the liquid crystal molecules 16 in the liquid crystal layer 15 is relatively large on the first substrate 11 side, and the liquid crystal molecules 16 are aligned so as to be approximately perpendicular to the direction parallel to the surface of the first substrate 11. In addition, the tilt angle of the liquid crystal molecules 16 in the liquid crystal layer 15 is relatively small on the second substrate 18 side, and the liquid crystal molecules 16 are aligned so as to be approximately parallel to the direction parallel to the surface of the first substrate 11.

[0040] 4 and 5, the alignment direction HX1 of the liquid crystal molecules 16 in a plan view is a direction along the first direction Dx. That is, the alignment direction HX1 of the liquid crystal molecules 16 is provided along the arrangement direction of the plurality of first electrodes 12 and the plurality of second electrodes 13. Furthermore, the alignment direction HX1 of the liquid crystal molecules 16 is arranged perpendicular to the first absorption axis AX1 of the first polarizer 21 and the second absorption axis AX2 of the second polarizer 22. Alternatively, the alignment direction HX1 of the liquid crystal molecules 16 may be arranged parallel to the first absorption axis AX1 of the first polarizer 21 and the second absorption axis AX2 of the second polarizer 22.

[0041] The control circuit 70 (see FIG. 1) controls the driving of the plurality of first electrodes 12 and the plurality of second electrodes 13 to switch the viewing angle of the first viewing angle control panel 20. Specifically, when the control circuit 70 does not supply voltage to the plurality of first electrodes 12 and the plurality of second electrodes 13 (hereinafter referred to as the "first state"), the liquid crystal molecules 16 of the liquid crystal layer 15 are hybrid-oriented as shown in FIG. 3. When the control circuit 70 supplies voltage to the plurality of first electrodes 12 and the plurality of second electrodes 13 (hereinafter referred to as the "second state"), the long axes LA of the liquid crystal molecules 16 of the liquid crystal layer 15 are oriented along the lateral electric field.

[0042] In other words, the liquid crystal layer 15 is switched between a first state in which the tilt angle formed between the long axis LA of the liquid crystal molecules 16 and a direction parallel to the surface of the first substrate 11 changes continuously along a direction perpendicular to the first substrate 11, and a second state in which the long axis LA of the liquid crystal molecules 16 is oriented in a direction along the transverse electric field.

[0043] With the above-described configuration, the optical element 10 controls the driving of the plurality of first electrodes 12 and the plurality of second electrodes 13 of the first viewing angle control panel 20, so that in the first state the liquid crystal molecules 16 are hybrid-oriented and an image can be displayed with a narrow viewing angle. In the second state, the liquid crystal molecules 16 are oriented in a direction substantially parallel to the surface of the first substrate 11 and an image can be displayed with a wide viewing angle.

[0044] Furthermore, because the liquid crystal layer 15 contains liquid crystal molecules 16 with positive dielectric anisotropy, it has lower viscosity than liquid crystal molecules with negative dielectric anisotropy and exhibits good responsiveness to voltage on / off switching. Furthermore, because the plurality of first electrodes 12 and the plurality of second electrodes 13 are configured to generate a transverse electric field, in the second state the liquid crystal molecules 16 of the liquid crystal layer 15 are aligned in a direction substantially parallel to the surface of the first substrate 11. This eliminates the need for a viewing angle compensation film such as a C-plate, making it possible to control the viewing angle with a simpler configuration.

[0045] (Example) Fig. 6 is a graph showing the relationship between brightness and polar angle for the display devices according to Examples 1 and 2. Fig. 7 is a diagram showing the viewing angle dependence of brightness in a first state for the display device according to Example 1. Fig. 8 is a diagram showing the viewing angle dependence of brightness in a second state for the display device according to Example 1. Fig. 9 is a diagram showing the viewing angle dependence of brightness in a second state for the display device according to Example 2.

[0046] The layered configurations of the optical elements 10 according to Examples 1 and 2 are both similar to the examples shown in Figs. 1 to 5. Examples 1 and 2 differ in the arrangement interval Px (see Fig. 4) between the plurality of first electrodes 12 and the plurality of second electrodes 13. In Example 1, the arrangement interval Px between the first electrodes 12 and the second electrodes 13 adjacent to each other in the first direction Dx is 12 µm. In Example 2, the arrangement interval Px between the first electrodes 12 and the second electrodes 13 adjacent to each other in the first direction Dx is 24 µm.

[0047] In Graph 1 shown in Fig. 6, the horizontal axis represents the polar angle θ (°) and the vertical axis represents the brightness (au). Fig. 6 shows the simulation results of the polar angle dependence of relative brightness when the brightness in the front direction (polar angle θ = 0°) of Example 1 and Example 2 is set to be the same.

[0048] 7 to 9 show isophotes connecting regions exhibiting equal brightness for each polar angle and each azimuth angle. In FIGS. 7 to 9, the azimuth angle φ is the angle formed with respect to a direction parallel to the first direction Dx. In each of FIGS. 7 to 9, the right side of the circle center (one side of the first direction Dx) has an azimuth angle φ=0°, and the left side of the circle center (the other side of the first direction Dx) has an azimuth angle φ=180°. The upper side of the circle center (one side of the second direction Dy) has an azimuth angle φ=90°, and the lower side of the circle center (the other side of the second direction Dy) has an azimuth angle φ=270°. The center of the circle corresponds to the normal direction (polar angle θ=0°) of the display device 100 (optical element 10), and concentric circles (shown by dotted lines) centered on the normal direction correspond to polar angles θ=20°, 40°, 60°, and 80°, respectively. Graph 1 shown in FIG. 6 shows the polar angle dependency in the second direction Dy (the direction from the azimuth angle φ=90° to the azimuth angle φ=270°).

[0049] 6, in Example 1, brightness is suppressed on the high polar angle side in the first state in which no voltage is supplied to the plurality of first electrodes 12 and the plurality of second electrodes 13. Specifically, in the first state, brightness is suppressed in the range of polar angles θ=−50° or less and θ=50° or more.

[0050] 7, in Example 1, the brightness has azimuth angle dependence in the first state. Specifically, Example 1 in the first state has a wide viewing angle in the first direction Dx (the direction from azimuth angle φ=0° to azimuth angle φ=180°). In contrast, Example 1 in the first state has a narrow viewing angle in the second direction Dy (the direction from azimuth angle φ=90° to azimuth angle φ=270°).

[0051] 6, in Example 1, in the second state in which voltages are supplied to the plurality of first electrodes 12 and the plurality of second electrodes 13, a wider viewing angle can be achieved than in the first state. Specifically, in the second state, the display is brighter than the first state over most of the range of polar angles θ except for θ=0°. In particular, in the second state, the contrast ratio relative to the brightness in the first state is large near polar angles θ=-50° and θ=50°.

[0052] As shown in FIG. 7 , in Example 1, a wide viewing angle can be achieved at all azimuth angles φ in the second state. Furthermore, the second state of Example 1 has symmetrical azimuth angle dependence of brightness. Specifically, the second state of Example 1 has viewing angle dependence of brightness that is substantially line-symmetrical with respect to a reference line that passes through the polar angle θ=0° and is parallel to the second direction Dy. The second state of Example 1 has viewing angle dependence of brightness that is substantially line-symmetrical with respect to a reference line that passes through the polar angle θ=0° and is parallel to the first direction Dx.

[0053] As a result, the display device 100 of Example 1 can achieve a narrow viewing angle that makes the image invisible from the left and right directions while ensuring image brightness in the front direction (polar angle θ=0°) in the first state by arranging the optical element 10 with the azimuth angle φ=0° and the 180° direction in the up and down directions of the display device 100. Furthermore, the display device 100 of Example 1 can achieve a wide viewing angle that makes the image visible from the front direction and the left and right directions in the second state.

[0054] Note that Figure 6 omits the polar angle dependence of brightness in the first state of Example 2, but in the first state in which no voltage is supplied to the multiple first electrodes 12 and the multiple second electrodes 13, the polar angle dependence of brightness in Example 2 is substantially equivalent to the polar angle dependence of brightness in Example 1.

[0055] 6 and 9, in Example 2, in the second state in which voltages are supplied to the plurality of first electrodes 12 and the plurality of second electrodes 13, the brightness has a viewing angle dependency that is substantially the same as that of the second state of Example 1. That is, even in the second state of Example 2, a wider viewing angle can be achieved compared to the first state.

[0056] As shown in Examples 1 and 2, it was demonstrated that the viewing angle can be controlled between the first state and the second state even when the arrangement distance Px between the first electrodes 12 and the second electrodes 13 is changed. Furthermore, as shown in FIGS. 8 and 9, in Examples 1 and 2, in the second state in which voltages are supplied to the plurality of first electrodes 12 and the plurality of second electrodes 13, polar angle dependency is exhibited in which brightness changes continuously in an oblique direction (e.g., azimuth angle φ=+45°) relative to the polar angle θ=0°, and no brightness distribution such as locally brightening or locally darkening occurs. Therefore, it was demonstrated that Examples 1 and 2 can display good images without providing a viewing angle compensation film such as a C-plate.

[0057] The first embodiment and each example described above are merely examples and can be modified as appropriate. For example, the arrangement distance Px between the first electrode 12 and the second electrode 13 is not limited to 12 μm or 24 μm. Furthermore, the first electrode 12 and the second electrode 13 may have any shape or arrangement as long as they are configured to generate a transverse electric field.

[0058] (First Modification) 10 is a cross-sectional view schematically showing an example of the configuration of an optical element according to Modification 1. In the following description, the same components as those described in the above embodiment are denoted by the same reference numerals, and redundant description will be omitted.

[0059] 10 , an optical element 10A according to the first modification differs from the first embodiment in the configuration of a first electrode 12A and a second electrode 13A of a first viewing angle control panel 20A. Specifically, the second electrode 13A is provided on the surface of the first substrate 11 facing the second substrate 18. An insulating film 19 is provided to cover the second electrode 13A. A plurality of first electrodes 12A are provided on the insulating film 19. The first substrate 11, the second electrode 13A, the insulating film 19, and the plurality of first electrodes 12A are stacked in this order in the third direction Dz.

[0060] The second electrode 13A is supplied with a predetermined reference potential and is provided as a common electrode for the plurality of first electrodes 12A. In Fig. 10, one second electrode 13A is provided for the plurality of first electrodes 12A, but this is not limiting, and a plurality of second electrodes 13A may be provided.

[0061] With this configuration, when a voltage is supplied to the plurality of first electrodes 12A and second electrodes 13A, a fringe electric field is generated between the first electrodes 12A and the second electrodes 13A. In the first modification, the liquid crystal molecules 16 of the liquid crystal layer 15 are driven by the fringe electric field formed between the first electrodes 12A and the second electrodes 13A.

[0062] (Second Modification) Fig. 11 is a cross-sectional view schematically showing an example of the configuration of an optical element according to the second modification. As shown in Fig. 11, an optical element 10B according to the second modification is different from the first embodiment described above in the configuration in which electrodes are provided on each of the first substrate 11 and the second substrate 18 of a first viewing angle control panel 20B. Specifically, a plurality of first electrodes 12 and a plurality of second electrodes 13 are provided on the surface of the first substrate 11 facing the second substrate 18, and are alternately arranged in the first direction Dx. Furthermore, a plurality of first electrodes 12B and a plurality of second electrodes 13B are provided on the surface of the second substrate 18 facing the first substrate 11, and are alternately arranged in the first direction Dx.

[0063] The plurality of first electrodes 12B provided on the second substrate 18 are arranged at positions overlapping the plurality of first electrodes 12 on the first substrate 11. The plurality of second electrodes 13B provided on the second substrate 18 are arranged at positions overlapping the plurality of second electrodes 13 on the first substrate 11.

[0064] With this configuration, when a voltage is supplied to the plurality of first electrodes 12, 12A and second electrodes 13, 13A, a transverse electric field is generated between the first electrode 12 and the second electrode 13, and a transverse electric field is generated between the first electrode 12A and the second electrode 13A. In the second modified example, the liquid crystal molecules 16 of the liquid crystal layer 15 are driven by the transverse electric field formed between the first electrode 12 and the second electrode 13, and the transverse electric field formed between the first electrode 12B and the second electrode 13B.

[0065] (Second embodiment) Fig. 12 is a cross-sectional view schematically showing a display device according to the second embodiment. Fig. 13 is an explanatory diagram for explaining the relationship between the absorption axis direction of each polarizer and the alignment direction of the liquid crystal layer of the first view angle control panel in the display device according to the second embodiment.

[0066] 12 and 13, the display device 100A according to the second embodiment further includes a fourth polarizing plate 24, a second viewing angle control panel 31, a fifth polarizing plate 25, and a half-wave plate 32. The fourth polarizing plate 24, the second viewing angle control panel 31, the fifth polarizing plate 25, and the half-wave plate 32 are stacked in this order between the lighting device 60 and the optical element 10.

[0067] The second viewing angle control panel 31 has a TN type liquid crystal layer. That is, in the second viewing angle control panel 31, by performing alignment treatment on the upper and lower alignment films, respectively, the liquid crystal molecules of the liquid crystal layer are aligned so as to be twisted continuously by 90° between the upper and lower substrates in a plan view. In addition, the half-wave plate 32 imparts a phase difference of half a wavelength to the transmitted light.

[0068] 13 , the fourth absorption axis AX4 of the fourth polarizing plate 24 is disposed perpendicular to the fifth absorption axis AX5 of the fifth polarizing plate 25. The fifth absorption axis AX5 of the fifth polarizing plate 25 is disposed at an azimuth angle φ=45° with respect to the first absorption axis AX1 of the first polarizing plate 21 of the optical element 10. The stretching axis direction LX1 of the half-wave plate 32 is disposed midway between the first absorption axis AX1 of the first polarizing plate 21 and the fifth absorption axis AX5 of the fifth polarizing plate 25. With this configuration, in the second embodiment, it is possible to appropriately adjust the polarization state of light incident on the first polarizing plate 21 of the optical element 10.

[0069] (Third modified example of the second embodiment) Fig. 14 is a cross-sectional view schematically showing a display device according to a third modified example of embodiment 2. Fig. 15 is an explanatory diagram for explaining the relationship between the absorption axis direction of each polarizer and the alignment direction of the liquid crystal layer of the first view angle control panel in the display device according to the third modified example of embodiment 2.

[0070] As shown in Figures 14 and 15, a display device 100B according to the third variant of the second embodiment has a half-wave plate 32, a fourth polarizer 24, a second viewing angle control panel 31, a fifth polarizer 25, a half-wave plate 33, and a sixth polarizer 26 stacked in this order between the optical element 10 and the display panel 50.

[0071] As shown in FIG. 15 , the fourth absorption axis AX4 of the fourth polarizer 24 is disposed at an azimuth angle φ=45° with respect to the second absorption axis AX2 of the second polarizer 22 of the optical element 10. The stretching axis direction LX1 of the half-wave plate 32 is disposed midway between the second absorption axis AX2 of the second polarizer 22 and the fourth absorption axis AX4 of the fourth polarizer 24. The fifth absorption axis AX5 of the fifth polarizer 25 is disposed orthogonal to the fourth absorption axis AX4 of the fourth polarizer 24. The sixth absorption axis AX6 of the sixth polarizer 26 is disposed orthogonal to the fifth absorption axis AX5 of the fifth polarizer 25. The stretching axis direction LX2 of the half-wave plate 33 is disposed midway between the fifth absorption axis AX5 of the fifth polarizer 25 and the sixth absorption axis AX6 of the sixth polarizer 26. With this configuration, in the third modified example of the second embodiment, the polarization state of light that has passed through the optical element 10 and is incident on the display panel 50 can be appropriately adjusted.

[0072] In the second embodiment and the third modified example, a configuration including the optical element 10 shown in the first embodiment has been described. However, the present invention is not limited to this, and the second embodiment and the third modified example can also be combined with the optical elements 10A and 10B according to the first modified example or the second modified example.

[0073] Although preferred embodiments of the present invention have been described above, the present invention is not limited to such embodiments. The contents disclosed in the embodiments are merely examples, and various modifications are possible without departing from the spirit of the present invention. Appropriate modifications made without departing from the spirit of the present invention naturally fall within the technical scope of the present invention. At least one of various omissions, substitutions, and modifications of components can be made without departing from the spirit of each of the above-described embodiments and modifications. [Explanation of symbols]

[0074] 10, 10A, 10B Optical elements 11 First board 12, 12A, 12B 1st electrode 13, 13A, 13B 2nd electrode 14 First alignment film 15 Liquid crystal layer 16 Liquid crystal molecules 17 Second alignment film 18 Second board 20, 20A, 20B First viewing angle control panel 21 First polarizing plate 22 Second polarizing plate 23 Third polarizing plate 24 Fourth polarizer 25 5th polarizer 26 6th polarizer 31 Second viewing angle control panel 32, 33 1 / 2 wavelength plate 50 Display Panel 60 Lighting Equipment 70 Control circuit 100, 100A, 100B display device AX1 First absorption axis AX2 Second absorption axis HX1 orientation LX1, LX2 Stretching axis direction

Claims

1. a first polarizing plate having a first absorption axis; a second polarizing plate facing the first polarizing plate and having a second absorption axis; a first viewing angle control panel disposed between the first polarizing plate and the second polarizing plate; The first viewing angle control panel is a first substrate; a second substrate facing the first substrate; a liquid crystal layer provided between the first substrate and the second substrate; a plurality of electrodes provided on at least one of the first substrate and the second substrate, the electrodes generating a transverse electric field in a predetermined direction; the liquid crystal layer contains liquid crystal molecules with positive dielectric anisotropy, the liquid crystal molecules are hybrid-oriented in the absence of the transverse electric field; the first polarizer, the first substrate, the liquid crystal layer, the second substrate, and the second polarizer are laminated in this order; In a plan view, the first absorption axis of the first polarizing plate is arranged parallel to the second absorption axis of the second polarizing plate, The alignment direction of the liquid crystal molecules is arranged parallel to or perpendicular to the first absorption axis of the first polarizer and the second absorption axis of the second polarizer. Optical elements.

2. The liquid crystal layer is switched between a first state in which a tilt angle formed between the long axes of the liquid crystal molecules and a direction parallel to the surface of the first substrate continuously changes along a direction perpendicular to the first substrate, and a second state in which the long axes of the liquid crystal molecules are aligned in a direction along the transverse electric field. The optical element according to claim 1 .

3. the electrodes include a plurality of first electrodes and a plurality of second electrodes; The first electrodes and the second electrodes are provided on a surface of the first substrate facing the second substrate, and are alternately arranged in the predetermined direction. The optical element according to claim 1 .

4. the electrodes include a plurality of first electrodes and a plurality of second electrodes; The first electrodes and the second electrodes are provided on a surface of the first substrate facing the second substrate, and are alternately arranged in the predetermined direction. The second electrodes are also provided on a surface of the second substrate facing the first substrate, and are alternately arranged in the predetermined direction. The optical element according to claim 1 .

5. the electrodes include a plurality of first electrodes and at least one second electrode; At least one second electrode, an insulating film, and a plurality of first electrodes are stacked in this order on the surface of the first substrate facing the second substrate. The optical element according to claim 1 .

6. The optical element according to any one of claims 1 to 5; a display panel laminated with the optical element; an illumination device that irradiates the optical element with light; Display device.

7. Further, a second viewing angle control panel including a TN type liquid crystal layer is provided, The second viewing angle control panel is disposed between the lighting device and the optical element. The display device according to claim 6.

8. Further, a second viewing angle control panel including a TN type liquid crystal layer is provided, The second viewing angle control panel is disposed between the optical element and the display panel. The display device according to claim 6.

Images