Display device

Abstract

To provide a display device capable of further suppressing color deviation.SOLUTION: A display device includes: a display panel having a display region that outputs an image; a light source that emits light from one surface side of the display panel; and a light adjuster interposed between the display panel and the light source and capable of changing a transmission degree of light between the display panel and the light source. In the light adjuster, a first polarization layer, a first liquid crystal panel, a second polarization layer, a second liquid crystal panel, and a third polarization layer are stacked from the light source side toward the display panel side. One of the first liquid crystal panel and the second liquid crystal panel has a relatively higher transmittance of green light than the transmittance of red light and the transmittance of blue light. The other of the first liquid crystal panel and the second liquid crystal panel has a relatively lower transmittance of green light than the transmittance of red light and the transmittance of blue light.SELECTED DRAWING: Figure 19

Description

[Technical Field]

[0001] The present disclosure relates to a display device. [Background technology]

[0002] In recent years, there has been a demand for display devices that allow the viewing angle range in which an image can be viewed to be changed. For example, in display devices mounted on vehicles such as four-wheeled automobiles, it is required to realize a viewing angle range in which an image can be viewed from the passenger seat, but cannot be viewed from the driver's seat only while driving. To realize such a viewing angle range, a technology has been proposed in which a light-control liquid crystal panel with a switchable viewing angle range is superimposed on an image display panel (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-195388 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration described in Patent Document 1, the liquid crystal panel for dimming and the panel for image display overlap, so that both the color reproduction characteristics of the liquid crystal panel for dimming and the color reproduction characteristics of the panel for image display are reflected in the colors of the output image. Therefore, if there is a color bias, such as a specific color being strong or a specific color being weak, in the color reproduction due to at least one of the color reproduction characteristics of the liquid crystal panel for dimming and the color reproduction characteristics of the panel for image display, this color bias is reflected in the colors of the output image, which can degrade the quality of the output image.

[0005] The present disclosure has been made in view of the above-mentioned problems, and aims to provide a display device that can further suppress color bias. [Means for solving the problem]

[0006] A display device according to one embodiment of the present disclosure comprises a display panel having a display area for outputting an image, a light source for irradiating light from one side of the display panel, and a dimming unit interposed between the display panel and the light source and configured to change the degree of light transmission between the display panel and the light source, wherein the dimming unit has a first polarizing layer, a first liquid crystal panel, a second polarizing layer, a second liquid crystal panel, and a third polarizing layer stacked from the light source side toward the display panel side, and one of the first liquid crystal panel and the second liquid crystal panel has a relatively high transmittance for green light compared to the transmittance for red light and the transmittance for blue light, and the other of the first liquid crystal panel and the second liquid crystal panel has a relatively low transmittance for green light compared to the transmittance for red light and the transmittance for blue light. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing an example of the main configuration of a display device according to an embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of each of the components of the display device. [Figure 3] FIG. 3 is a diagram showing the change in the deflection direction of light that occurs from the light source until it is emitted to the other surface side of the display device. [Figure 4] Figure 4 is a diagram showing the relationship between the rubbing directions R6a and R6b of the alignment films of the second liquid crystal panel and the transmission axis directions of the second polarizing layer and the third polarizing layer, which are arranged opposite each other in the third direction across the second liquid crystal panel. [Figure 5] FIG. 5 is a diagram showing the orientation of liquid crystal molecules when the liquid crystal panel is not operating (OFF). [Figure 6] FIG. 6 is a diagram showing the orientation of liquid crystal molecules when the liquid crystal panel is in operation (ON). [Figure 7] FIG. 7 is a diagram showing an example of the viewing angle characteristics of a display device that are caused by the degree of light transmission when the liquid crystal panel is in operation (ON). [Figure 8]FIG. 8 is a schematic diagram showing an example of the relationship between a display device, a user who can view an image regardless of whether the liquid crystal panel is operating or not (ON / OFF), and a user who cannot view an image when the liquid crystal panel is operating (ON). [Figure 9] FIG. 9 is a schematic diagram showing the difference between the image viewed by a user viewing the display device from the front and the image viewed by a user viewing the display device obliquely. [Figure 10] FIG. 10 is a graph showing the relationship between the polar angle and the light transmittance when the liquid crystal panel is in operation (ON) for each of the E mode and the O mode. [Figure 11] FIG. 11 is a graph showing the normalized transmittance of the display device in the second state for each of the E mode only, the O mode only, and the combination of the E mode and the O mode. [Figure 12] FIG. 12 is a graph showing the normalized transmittance of the display device in the second state for each of the E mode only, the O mode only, and the combination of the E mode and the O mode. [Figure 13] FIG. 13 is a graph showing the color shift tendency in the first direction of the first liquid crystal panel. [Figure 14] FIG. 14 is a graph showing the color shift tendency in the first direction of the second liquid crystal panel. [Figure 15] Figure 15 is a graph showing the difference between a display device of an embodiment having a dimming unit including a first liquid crystal panel and a second liquid crystal panel as described with reference to Figures 13 and 14, and a comparative example in which the color shift tendency in the first direction is not particularly taken into consideration. [Figure 16] FIG. 16 is a schematic diagram for explaining the relationship between the alignment of the liquid crystal and the retardation value (Δnd). [Figure 17] FIG. 17 is a diagram schematically showing the relationship between the fast axis and slow axis of a structure that generates retardation and the thickness of the structure. [Figure 18] FIG. 18 is a graph illustrating an example of a method for setting the retardation value (Δnd). [Figure 19] FIG. 19 is a graph schematically showing the relationship between the light transmittance and the color of light of each of the first and second liquid crystal panels. [Figure 20] FIG. 20 is a graph showing the relationship between the cell gap of the liquid crystal panel and the transmittance of light passing through the liquid crystal panel in the third direction when the refractive index difference Δn is 0.2. [Figure 21] FIG. 21 is a graph showing the relationship between the retardation value (Δnd) of the liquid crystal panel and the transmittance of light passing through the liquid crystal panel in the third direction. [Figure 22] FIG. 22 is a graph showing the relationship between the first direction polar angle with respect to the display device from a user viewing the output of the display device and the transmittance of chromaticity x for each cell gap of the first liquid crystal panel. [Figure 23] FIG. 23 is a graph showing the relationship between the first direction polar angle with respect to the display device from the user viewing the output of the display device and the chromaticity y for each cell gap of the first liquid crystal panel. [Figure 24] FIG. 24 is a graph showing the relationship between the first direction polar angle with respect to the display device from the user viewing the output of the display device and the chromaticity x for each cell gap of the second liquid crystal panel. [Figure 25] FIG. 25 is a graph showing the relationship between the first direction polar angle with respect to the display device from the user viewing the output of the display device and the chromaticity y for each cell gap of the second liquid crystal panel. [Figure 26] FIG. 26 is a plan view showing an example of a pixel layout in a display panel. [Figure 27] Figure 27 is a graph showing the relationship between the polar angle and the light transmittance when a liquid crystal panel used as an E-mode liquid crystal panel is operating (ON) when the twist angle is 90° (twist 90°) and when the twist angle is 80° (twist 80°). [Figure 28] Figure 28 is a graph showing the normalized transmittance on one side and the other side of the first direction when a liquid crystal panel provided as an E-mode liquid crystal panel is operating (ON) when the twist angle is 90° (twist 90°) and when the twist angle is 80° (twist 80°). [Figure 29]Figure 29 is a graph showing the normalized transmittance on one side and the other side of the first direction when a liquid crystal panel provided as an E-mode liquid crystal panel is operating (ON) when the twist angle is 90° (twist 90°) and when the twist angle is 80° (twist 80°). [Figure 30] Figure 30 is a graph showing the normalized transmittance on one side and the other side of the first direction when a liquid crystal panel provided as an O-mode liquid crystal panel is operating (ON) when the twist angle is 90° (twist 90°) and when the twist angle is 80° (twist 80°). [Figure 31] Figure 31 is a graph showing the normalized transmittance on one side and the other side of the first direction when a liquid crystal panel provided as an O-mode liquid crystal panel is operating (ON) when the twist angle is 90° (twist 90°) and when the twist angle is 80° (twist 80°). [Figure 32] FIG. 32 is a schematic diagram showing an example of a main configuration of a display device according to the second modification. [Figure 33] FIG. 33 is a schematic diagram showing an example of a polarization angle of the polarized light generating layer that can be employed in the second modification, and an angle range within which the polarization angle can be set. DETAILED DESCRIPTION OF THE INVENTION

[0008] Each embodiment of the present disclosure will be described below with reference to the drawings. The disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily conceive while maintaining the gist of the invention are naturally included within the scope of the present disclosure. Furthermore, to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and are not intended to limit the interpretation of the present disclosure. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings will be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0009] (Embodiment) FIG. 1 is a schematic diagram showing an example of the main configuration of a display device 1 according to an embodiment. The display device 1 includes a light control unit 10, a display panel 30, a light source 60, a retardation generating layer 51, and a retardation generating layer 52. The direction in which the light control unit 10, the display panel 30, the light source 60, the retardation generating layer 51, and the retardation generating layer 52 overlap is defined as a third direction Z. One of two directions perpendicular to the third direction Z is defined as a first direction X, and the other is defined as a second direction Y. The first direction X and the second direction Y are perpendicular to each other. In the display device 1, the light source 60, the retardation generating layer 51, the light control unit 10, the retardation generating layer 52, and the display panel 30 overlap in this order from one side to the other side of the third direction Z.

[0010] Fig. 2 is a schematic cross-sectional view of each of the components of the display device 1. Note that in Fig. 2, there are gaps between the components of the light source 60, the retardation generating layer 51, the dimming section 10, the retardation generating layer 52, and the display panel 30. These gaps are provided for the purpose of making the drawing easier to understand, and are not necessary in the actual display device 1 (see Fig. 1).

[0011] The dimming unit 10 is configured such that a first polarizing layer 11, a first liquid crystal panel 20A, a second polarizing layer 12, a second liquid crystal panel 20B, and a third polarizing layer 13 are stacked from one side to the other side in the third direction Z. The first polarizing layer 11, the second polarizing layer 12, and the third polarizing layer 13, as well as a fourth polarizing layer 41 and a fifth polarizing layer 42 described below, are optical components configured to maximize the transmission of light polarized in a specific direction. This specific direction is referred to as the transmission axis direction. The transmission axis direction is aligned with the polarizing plate. In other words, the transmission axis direction is perpendicular to the third direction Z. The direction perpendicular to the transmission axis direction and the third direction Z is referred to as the absorption axis direction. The absorption axis direction is the polarization direction through which light is least transmitted by the polarizing plate.

[0012] The first liquid crystal panel 20A and the second liquid crystal panel 20B are liquid crystal panels. The first liquid crystal panel 20A and the second liquid crystal panel 20B have the same configuration as devices, except for their different locations. Hereinafter, the term "liquid crystal panel 20" encompasses the first liquid crystal panel 20A and the second liquid crystal panel 20B. In other words, the description of the liquid crystal panel 20 can be applied to both the first liquid crystal panel 20A and the second liquid crystal panel 20B. The liquid crystal panel 20 of this embodiment is a so-called TN (Twisted Nematic) liquid crystal panel.

[0013] The liquid crystal panel 20 has a configuration in which a first substrate 21 is provided on one side of the liquid crystal LM and a second substrate 22 is provided on the other side. The first substrate 21 and the second substrate 22 are light-transmitting substrates. The light-transmitting substrate is, for example, a glass substrate, but is not limited to this and may be a substrate made of another light-transmitting material. Hereinafter, when referring to one side, it refers to the surface on one side in the third direction Z in a plate-like configuration. Furthermore, when referring to the other side, it refers to the surface on the other side in the third direction Z in a plate-like configuration.

[0014] A first electrode FE1 is formed on the other surface of the first substrate 21. A second electrode FE2 is formed on one surface of the second substrate 22. The first electrode FE1 and the second electrode FE2 are electrodes provided to cover the display area AA. The other surface of the first electrode FE1 and the other surface of the first substrate 21 in an area where the first electrode FE1 is not formed are covered with an insulating layer 23. One surface of the second electrode FE2 and the one surface of the second substrate 22 in an area where the second electrode FE2 is not formed are covered with an insulating layer 24. The display area AA will be described later.

[0015] At least one of the first electrode FE1 and the second electrode FE2 is provided so that the potential can be changed depending on whether the liquid crystal panel 20 is in operation (ON) or not (OFF). That is, the voltage generated between the first electrode FE1 and the second electrode FE2 differs when the liquid crystal panel 20 is in operation (ON) and when it is not in operation (OFF).

[0016] Liquid crystal LM is interposed between insulating layer 23 and insulating layer 24, at least within display area AA. In addition, a seal 25 is interposed between insulating layer 23 and insulating layer 24 outside display area AA. Although not shown, seal 25 is a frame-shaped member that surrounds liquid crystal LM when viewed from the front on a plane (XY plane) perpendicular to third direction Z. Liquid crystal LM is enclosed within liquid crystal panel 20 by being surrounded by seal 25 between insulating layer 23 and insulating layer 24.

[0017] An alignment film 23a is provided on the other surface of the insulating layer 23 in an area that covers at least the display area AA. An alignment film 24a is provided on one surface of the insulating layer 24 in an area that covers at least the display area AA. The alignment films 23a and 24a orient the liquid crystal molecules contained in the liquid crystal LM in a specific direction. The alignment of the liquid crystal molecules changes when the potential difference between the first electrode FE1 and the second electrode FE2 changes.

[0018] The display panel 30 is a liquid crystal panel different from the liquid crystal panel 20. The display panel 30 has a plurality of pixels. The display panel 30 is a liquid crystal panel for displaying images that is provided so that the degree of light transmission at each position of the plurality of pixels can be individually controlled in response to input image data from the outside.

[0019] The display panel 30 shown in Fig. 2 is a so-called IPS (In Plane Switching) liquid crystal panel. The display panel 30 has a pixel substrate 31 on one side in the third direction Z with a liquid crystal LQ sandwiched therebetween, and a counter substrate 32 on the other side. Furthermore, a fourth polarizing layer 41 is provided on one surface of the pixel substrate 31. A fifth polarizing layer 42 is provided on the other surface of the counter substrate 32. Hereinafter, the term "panel section DP" refers to the portion of the display panel 30 excluding the fourth polarizing layer 41 and the fifth polarizing layer 42.

[0020] On the other surface of the pixel substrate 31, a common electrode CE, an insulating layer 33, a pixel electrode P, an insulating layer 34, etc. are laminated from one side to the other in the third direction Z. A color filter 35, etc. are laminated on one surface of the counter substrate 32. In addition, outside the display area AA, a seal 36 is interposed between the insulating layer 34 and the color filter 35. The seal 36 has the same shape as the seal 25 described above. The liquid crystal LQ is enclosed within the display panel 30 by being surrounded by the seal 36 between the insulating layer 34 and the color filter 35.

[0021] The display area AA is an area in the display panel 30 where multiple pixel electrodes P are arranged. The multiple pixel electrodes P are arranged two-dimensionally along the XY plane within the display area AA. The display panel 30 is a so-called active matrix display panel that is configured to be able to display and output any image by individually controlling the degree of light transmittance of each pixel electrode P. More specifically, in the display panel 30 of this embodiment, a reference potential is applied to the common electrode CE. Furthermore, individual potentials (pixel signals) are applied to the multiple pixel electrodes P, thereby individually controlling the degree of light transmittance of each pixel electrode P. Therefore, the display area AA can be said to be an area where images are displayed and output.

[0022] The retardation generating layer 51 and the retardation generating layer 52 are optical elements that change the phase of light entering from one side in the third direction Z and transmit the light to the other side in the third direction Z. The retardation generating layer 51 and the retardation generating layer 52 in the embodiment are so-called half-wave plates.

[0023] The light source 60 emits light toward the other surface on which the polarization generating layer 53 is provided. The polarization generating layer 53 is an optical element that polarizes the light emitted from the other surface of the light source 60 at a specific angle. The polarization generating layer 53 is, for example, a DBEF (Dual Brightness Enhancement Film), but is not limited to this, and may be any other element as long as it is capable of polarizing the light emitted from the other surface of the light source 60 at a specific angle. The light generated by the light source 60 passes through the polarization generating layer 53, the dimming unit 10, the fourth polarizing layer 41, the display panel 30, and the fifth polarizing layer 42, and is emitted to the other surface of the display device 1.

[0024] Next, a change in the deflection direction of light that occurs before the light generated by the light source 60 is emitted to the other surface side of the display device 1 will be described with reference to FIG.

[0025] FIG. 3 is a diagram showing changes in the polarization direction of light that occur before light generated by the light source 60 is emitted to the other side of the display device 1. In the following description, polarization along the first direction X is referred to as 0° polarization. In addition, in the description with reference to FIG. 3, the polarization angle is shown as an acute angle less than 180° with respect to the 0° polarization. In addition, in the description with reference to FIG. 3, among changes in the polarization direction of light, a change in counterclockwise rotation by r° along the XY plane is referred to as a "change of +r°," and a change in the opposite (clockwise) rotation by r° is referred to as a "change of -r°." r is a real number greater than or equal to 0.

[0026] In this embodiment, the polarization axis direction V01 of the polarization generating layer 53 is determined so as to transmit the light emitted from the other surface of the light source 60 as 0° polarized light. Therefore, the polarized light that passes through the polarization generating layer 53 and enters the retardation generating layer 51 is 0° polarized light.

[0027] As described above, the retardation generating layer 51 is a half-wave plate. The retardation generating layer 51 of this embodiment generates a change in the counterclockwise (+) direction. The retardation generating layer 51 has a slow axis direction V02 set to +22.5° relative to the polarized light (0°) transmitted through the polarized light generating layer 53. As a result, when the polarized light passes through the retardation generating layer 51, a change of +45° occurs in the polarized light. Therefore, the polarized light that passes through the retardation generating layer 51 and enters the first polarizing layer 11 is polarized at 45°. FIG. 3 shows the angle V02b of the polarized light incident on the retardation generating layer 51 and the angle V02a of the polarized light that has passed through the retardation generating layer 51.

[0028] The first polarizing layer 11 has a transmission axis direction V03 determined so as to transmit a maximum amount of 45° polarized light. Therefore, the light that has passed through the retardation generation layer 51 can pass through the first polarizing layer 11. Furthermore, the polarized light that passes through the first polarizing layer 11 and enters the first liquid crystal panel 20A is polarized at 45°.

[0029] The liquid crystal panel 20 is configured to impart a change of +90° to polarized light transmitting from one side to the other in the third direction Z. That is, a change of +90° occurs in the polarized light when it passes through the first liquid crystal panel 20A. Therefore, the polarized light that passes through the retardation generation layer 51 and enters the first polarizing layer 11 is polarized at 135°. FIG. 3 shows the angle V04b of the polarized light that enters the first liquid crystal panel 20A and the angle V04a of the polarized light that has passed through the first liquid crystal panel 20A.

[0030] The second polarizing layer 12 has a transmission axis direction V05 determined so as to transmit a maximum amount of 135° polarized light. Therefore, the light that has passed through the first liquid crystal panel 20A can also pass through the second polarizing layer 12. Furthermore, the polarized light that passes through the second polarizing layer 12 and enters the second liquid crystal panel 20B is polarized at 135°.

[0031] By passing through the second liquid crystal panel 20B, the polarized light is changed by +90°. Therefore, the polarized light that passes through the retardation generation layer 51 and enters the first polarizing layer 11 can be said to be polarized at 225°, which is the same as polarized light at 45°. Figure 3 shows the angle V06b of the polarized light that enters the second liquid crystal panel 20B and the angle V046 of the polarized light that has passed through the second liquid crystal panel 20B.

[0032] The transmission axis direction V07 of the third polarizing layer 13 is determined so as to transmit a maximum amount of light polarized at 45°. Therefore, the light transmitted through the second liquid crystal panel 20B can be transmitted through the third polarizing layer 13. Furthermore, the polarized light transmitted through the third polarizing layer 13 and incident on the retardation generation layer 52 is polarized at 45°.

[0033] As described above, the retardation generating layer 52 is a half-wave plate. In this embodiment, the retardation generating layer 52 generates a change in the clockwise (-) direction. The retardation generating layer 52 has a slow axis direction V08 set to -22.5° relative to the polarized light (45°) transmitted through the polarized light generating layer 53. As a result, when the polarized light passes through the retardation generating layer 52, the polarized light changes by -45°. Therefore, the polarized light that passes through the retardation generating layer 52 and enters the fourth polarizing layer 41 is polarized at 0°. FIG. 3 shows the angle V08b of the polarized light incident on the retardation generating layer 52 and the angle V08a of the polarized light that has passed through the retardation generating layer 52.

[0034] The transmission axis direction V09 of the fourth polarizing layer 41 is determined so as to transmit 0° polarized light to the maximum extent. Therefore, the light that has passed through the phase difference generation layer 52 can pass through the fourth polarizing layer 41. Furthermore, the polarized light that passes through the fourth polarizing layer 41 and enters the panel unit DP is 0° polarized light.

[0035] The panel unit DP is configured to impart a +90° change to polarized light passing from one side to the other in the third direction Z. That is, a +90° change occurs in the polarized light as it passes through the panel unit DP. Therefore, the polarized light that passes through the panel unit DP and enters the fifth polarizing layer 42 is polarized at 90°. FIG. 3 shows the angle V10b of the polarized light that enters the panel unit DP and the angle V10a of the polarized light that has passed through the panel unit DP.

[0036] The fifth polarizing layer 42 has a transmission axis direction V11 determined so as to transmit a maximum amount of 90° polarized light. Therefore, light that has passed through the panel unit DP can pass through the fifth polarizing layer 42. In this way, a light transmission path LV is established from the light source 60 to the other surface side of the fifth polarizing layer 42.

[0037] Next, the liquid crystal panel 20 will be described in more detail with reference to FIGS.

[0038] 4 is a diagram showing the relationship between the rubbing directions R6a and R6b of the alignment films 23a and 24a of the second liquid crystal panel 20B and the transmission axis directions of the second polarizing layer 12 and the third polarizing layer 13 that are arranged to face each other in the third direction Z across the second liquid crystal panel 20B. In the description with reference to FIG. 4 and FIG. 7 described later, the direction toward one side of the first direction X (the right in FIG. 4) is defined as the 0° direction. Furthermore, the direction that forms an angle counterclockwise with the 0° direction is defined as the plus (+) angle (°) direction, and the direction that forms an angle clockwise with the 0° direction is defined as the minus (-) angle (°) direction.

[0039] The alignment films 23a and 24a are each subjected to a rubbing treatment on the surface facing the liquid crystal LM to orient the liquid crystal molecules in a specific direction. The specific direction determined by this rubbing treatment is the rubbing direction. The rubbing direction R6b of the alignment film 23a is 225° (-135°). The rubbing direction R6a of the alignment film 24a is 315° (-45°).

[0040] In the second liquid crystal panel 20B, one side of the first substrate 21 on which the alignment film 23a is laminated faces the second polarizing layer 12. As shown in Figures 3 and 4, the transmission axis direction V5 of the second polarizing layer 12 is 135°. That is, the rubbing direction R6b of the alignment film 23a and the transmission axis direction V5 of the second polarizing layer 12 are perpendicular to each other.

[0041] In the second liquid crystal panel 20B, the second substrate 22 on which the alignment film 24a is laminated faces the third polarizing layer 13 on the other side. As shown in Figures 3 and 4, the transmission axis direction V7 of the third polarizing layer 13 is at an angle of 45°. That is, the rubbing direction R6a of the alignment film 24a and the transmission axis direction V7 of the third polarizing layer 13 are perpendicular to each other.

[0042] 4, in the second liquid crystal panel 20B of the embodiment, the rubbing direction of the alignment film laminated on the substrate and the alignment axis of the polarizing layer adjacent to the substrate are perpendicular to each other. In other words, the second liquid crystal panel 20B is provided as a so-called O-mode liquid crystal panel.

[0043] As described above, the first liquid crystal panel 20A and the second liquid crystal panel 20B have a common configuration (liquid crystal panel 20) as liquid crystal panels. Therefore, the rubbing direction R6b of the alignment film 23a on one side of the first liquid crystal panel 20A is 225° (−135°), similar to that of the second liquid crystal panel 20B. The transmission axis direction V3 of the first polarizing layer 11 disposed on one side of the first liquid crystal panel 20A is 45°. The rubbing direction R6a of the alignment film 24a on the other side of the first liquid crystal panel 20A is 315° (−45°), similar to that of the second liquid crystal panel 20B. The transmission axis direction V5 of the second polarizing layer 12 disposed on the other side of the first liquid crystal panel 20A is 135°. Therefore, in the first liquid crystal panel 20A of the embodiment, the rubbing direction of the alignment film stacked on the substrate and the alignment axis of the polarizing layer adjacent to the substrate are parallel. That is, the first liquid crystal panel 20A is provided as a so-called E-mode liquid crystal panel.

[0044] More specifically, the liquid crystal molecules contained in the liquid crystal LM can be considered to have an elongated spheroidal shape. Here, the long axis direction of the elongated spheroid is defined as ne(n extraordinary ) axis. The minor axis of the spheroid perpendicular to the ne axis is ordinary ) axis. In the E mode, the rubbing direction of the alignment film 23a is determined so that the transmission axis direction of the polarizing layer facing the alignment film 23a across the first substrate 21 is the same as the ne axis, and the rubbing direction of the alignment film 24a is determined so that the transmission axis direction of the polarizing layer facing the alignment film 24a across the second substrate 22 is the same as the ne axis. In the O mode, the rubbing direction of the alignment film 23a is determined so that the transmission axis direction of the polarizing layer facing the alignment film 23a across the first substrate 21 is the same as the no axis, and the rubbing direction of the alignment film 24a is determined so that the transmission axis direction of the polarizing layer facing the alignment film 24a across the second substrate 22 is the same as the no axis.

[0045] The rubbing direction does not limit the polarized light that is transmitted, that is, the alignment films 23a and 24a transmit light regardless of the rubbing direction.

[0046] The rubbing directions of the alignment films 23a and 24a affect the alignment of the liquid crystal molecules contained in the liquid crystal LM. In FIG. 4 and in FIGS. 5 and 6 described below, liquid crystal molecules contained in the liquid crystal LM are shown as liquid crystal molecules LM2. Among the liquid crystal molecules LM2, those located on the alignment film 23a side and aligned along the rubbing direction R6b are specifically referred to as liquid crystal molecules LMB. Among the liquid crystal molecules LM2, those located on the alignment film 24a side and aligned along the rubbing direction R6a are specifically referred to as liquid crystal molecules LMA. Among the liquid crystal molecules LM2, those located approximately midway between the liquid crystal molecules LMA and LMB in the third direction Z are specifically referred to as liquid crystal molecules LMC.

[0047] 4, when viewed from the front of the XY plane, the liquid crystal molecules LM2 closer to the alignment film 23a exhibit an alignment closer to the rubbing direction R6b, and the liquid crystal molecules LM2 closer to the alignment film 24a exhibit an alignment closer to the rubbing direction R6a. Due to the continuity of the change in alignment of the multiple liquid crystal molecules LM2 aligned in the third direction Z, the liquid crystal panel 20 changes the polarized light passing from one side to the other in the third direction Z by +90°.

[0048] FIG. 5 is a diagram showing the orientation of the liquid crystal molecules LM2 when the liquid crystal panel 20 is not operating (OFF). FIG. 6 is a diagram showing the orientation of the liquid crystal molecules LM2 when the liquid crystal panel 20 is operating (ON). As described above, the liquid crystal panel 20 is a TN-type liquid crystal panel. Therefore, when the liquid crystal panel 20 is not operating (OFF), as shown in FIG. 5, the long axis direction LX of the liquid crystal molecules LM2 is approximately aligned with the XY plane. On the other hand, when the liquid crystal panel 20 is operating (ON), the orientation of the liquid crystal molecules LM2 changes depending on the potential difference between the first electrode FE1 and the second electrode FE2 (see FIG. 2) so that the long axis direction LX faces the Z direction. Therefore, when the liquid crystal panel 20 is operating (ON), the long axis direction LX of the liquid crystal molecules LM2 intersects the XY plane, as shown in FIG. 6.

[0049] When the liquid crystal panel 20 is in the OFF state (OFF) as described with reference to FIG. 5, there is almost no difference in the degree of light transmission between one side in the first direction X and the other side in the first direction X. That is, when the first liquid crystal panel 20A and the liquid crystal panel 20 are both in the OFF state, when an image DSP (see FIG. 9) of the display device 1 is viewed from each of two viewpoints that are linearly symmetric in the first direction X with respect to a viewpoint where the display device 1 is viewed from the front, the brightness of the image perceived from the two viewpoints is almost the same. Hereinafter, the term "image DSP" refers to an image displayed and output by the display panel 30 of the display device 1. Furthermore, at this time, the image can be viewed from the viewpoint where the display device 1 is viewed from the front with greater brightness than from the other viewpoints. That is, when the liquid crystal panel 20 is in the OFF state, the degree to which light along the third direction Z passes through the liquid crystal panel 20 is greater than the degree to which light intersecting the third direction Z passes through the liquid crystal panel 20.

[0050] On the other hand, when the liquid crystal panel 20 is in the operation (ON) described with reference to Fig. 6, the degree of light transmission differs between one side in the first direction X and the other side in the first direction X. The viewing angle characteristics of the display device 1 caused by the degree of light transmission when the liquid crystal panel 20 is in the operation (ON) will be described with reference to Fig. 7.

[0051] Fig. 7 is a diagram showing an example of the viewing angle characteristics of the display device 1 that arise from the degree of light transmittance when the liquid crystal panel 20 is in operation (ON). The centers of the concentric circles in Fig. 7 correspond to the normal line of the display device 1 along the third direction Z, and the concentric circles centered on this normal line indicate tilt angles with respect to the normal line of 20°, 40°, 60°, and 80°, respectively. The characteristic diagram shown here was obtained by connecting regions of equal transmittance for each direction.

[0052] As shown in Fig. 7, when the user's line of sight with respect to the display device 1 is tilted toward one side (0°) of the first direction X, a relatively high light transmittance is obtained. Also, when the user's line of sight with respect to the display device 1 is along the normal direction, that is, when the user looks straight at the display device 1, a relatively high light transmittance is obtained. In contrast, when the user's line of sight with respect to the display device 1 is tilted toward the other side (180°) of the first direction X, the light transmittance becomes significantly lower than that of the one side. In particular, when the angle of tilt of the line of sight toward the other side (180°) of the first direction X exceeds 30°, in the example shown in Fig. 7, the transmittance becomes 3% or less, and the image becomes so dark that it is virtually unrecognizable to humans.

[0053] The viewing angle characteristics as described with reference to Fig. 7 can be used for display output control intended to make an image visible to a user viewing the display device 1 from the front or from one side in the first direction X, and to make an image invisible to a user viewing the display device 1 from the other side in the first direction X. An example of application of such display output control will be described with reference to Fig. 8.

[0054] Figure 8 is a schematic diagram showing an example of the relationship between the display device 1, a user U1 who can see the image DSP regardless of whether the liquid crystal panel 20 is operating or not (ON / OFF), and a user U2 who cannot see the image DSP when the liquid crystal panel 20 is operating (ON).

[0055] As shown in FIG. 8, the display device 1 and the user U1 face each other in the third direction Z. Although not shown in FIG. 8, the other side of the display device 1, i.e., the side of the fifth polarizing layer 42, is the user U1 side in FIG. 8. Therefore, image light LS1 directed toward the user U1 as a result of display output by the display device 1 is aligned with the third direction Z. In this positional relationship between the display device 1 and the user U1, the user U1 can be said to be at a viewpoint from which the display device 1 is viewed from the front. On the other hand, the user U2 is positioned to view the other side of the display device 1 obliquely from a direction tilted toward the other side of the first direction X with respect to the third direction Z. In other words, the image light LS2 directed toward the user U2 as a result of display output by the display device 1 is tilted toward the other side of the first direction X (180° in FIG. 7). In this positional relationship between the display device 1 and the user U2, the user U2 can be said to be at a viewpoint from which the display device 1 is viewed obliquely.

[0056] 8 is established when the display device 1 is installed in a four-wheeled vehicle in which the user U2 is seated in the driver's seat and the user U1 is seated in the passenger seat, but the case is not limited to this. For example, such a positional relationship may also be established when the display device 1 is installed as a personal monitor for each passenger in an aircraft such as a passenger plane, and other cases may also be included.

[0057] 9 is a schematic diagram showing the difference in image DSP viewed by a user viewing the display device 1 from the front and a user viewing the display device 1 obliquely. A user viewing the display device 1 from the front is, for example, user U1 in FIG. 8. A user viewing the display device 1 obliquely is, for example, user U2 in FIG. 8. In the description with reference to FIG. 9, a state of the display device 1 in which the display panel 30 displays and outputs an image and the liquid crystal panel 20 is inactive (OFF) is referred to as a first state. A state of the display device 1 in which the display panel 30 displays and outputs an image and the liquid crystal panel 20 is active (ON) is referred to as a second state.

[0058] As described above, when the liquid crystal panel 20 is not operating (OFF), the degree to which light traveling along the third direction Z passes through the liquid crystal panel 20 is equal to or greater than the degree to which light intersecting the third direction Z passes through the liquid crystal panel 20. Furthermore, as described with reference to FIG. 7, even when the liquid crystal panel 20 is operating (ON), a relatively high light transmittance is obtained when a user views the display device 1 from the front. Therefore, a user viewing the display device 1 from the front can view the image DSP shown in FIG. 9 regardless of whether the operating state of the display device 1 is the first state or the second state. Note that the form of the image DSP shown in FIG. 9 is merely an example and is not intended to be limiting. The display panel 30 can display and output any image.

[0059] On the other hand, as described with reference to FIG. 7, when the liquid crystal panel 20 is in operation (ON), if the user's line of sight with respect to the display device 1 is tilted toward the other side (180°) in the first direction X, the light transmittance is significantly lower than that on one side. Therefore, when the operating state of the display device 1 is the second state, a user who views the display device 1 obliquely from the other side in the first direction X cannot substantially view the image DSP. Note that when the operating state of the display device 1 is the second state, the significant decrease in light transmittance as described with reference to FIG. 7 does not occur even on the other side (180°) in the first direction X. Therefore, when the operating state of the display device 1 is in the first state, a user who views the display device 1 obliquely from the other side in the first direction X can view approximately the same image DSP as a user who views the display device 1 head-on.

[0060] As shown in FIG. 9, the image DSP is visually recognized as a rectangular image. That is, when the display device 1 is viewed from the front, the display area AA has a rectangular shape corresponding to the image DSP shown in FIG. 9. Two of the four sides of the rectangle are aligned along the first direction X, and the other two sides are aligned along the second direction Y. The light control unit 10 of the embodiment differentiates the degree of light transmission of rays inclined toward one side of the longitudinal direction (first direction X) of the rectangle from the degree of light transmission of rays inclined toward the other side of the longitudinal direction, based on the third direction Z. This allows the light control unit 10 to generate a visual difference between the first state and the second state described with reference to FIG. 9.

[0061] As described above, the light control unit 10 includes the first liquid crystal panel 20A provided as an E-mode liquid crystal panel and the second liquid crystal panel 20B provided as an O-mode liquid crystal panel. Hereinafter, the optical characteristics resulting from the coexistence of the E-mode liquid crystal panel and the O-mode liquid crystal panel will be described with reference to FIGS. 10 to 12.

[0062] Fig. 10 is a graph showing the relationship between the polar angle and the light transmittance when the liquid crystal panel 20 is operating (ON) for each of the E mode and the O mode. The horizontal axis (polar angle) in Fig. 10 and Fig. 27 described later indicates the angle between the reference angle (0°) along the third direction Z and the ray of light inclined toward the other side of the first direction X (the 180.0 side in Fig. 7) in the explanation with reference to Fig. 7. The vertical axis (transmittance) indicates the light transmittance of the ray corresponding to the polar angle indicated on the horizontal axis.

[0063] As shown in FIG. 10, the relationship between the polar angle and the light transmittance of the liquid crystal panel 20 when it is operating (ON) differs between a liquid crystal panel 20 (e.g., a first liquid crystal panel 20A) used as an E-mode liquid crystal panel and a liquid crystal panel 20 (e.g., a second liquid crystal panel 20B) used as an O-mode liquid crystal panel. Specifically, for the liquid crystal panel 20 used as an E-mode liquid crystal panel, the graph showing the relationship between polar angle and transmittance is a deep valley-like graph, where the transmittance peaks at a polar angle of 30° and then drops significantly to less than 1%. On the other hand, for the liquid crystal panel 20 used as an O-mode liquid crystal panel, the graph showing the relationship between polar angle and transmittance is a relatively gentler basin-like graph compared to the E-mode, where the transmittance is approximately 1% from a polar angle of 30° to 40°.

[0064] 10, by utilizing the difference in optical characteristics between the E mode and the O mode, it is possible to realize viewing angle characteristics that are more suitable for suppressing the visibility of the image DSP from the other side in the first direction X for the display device 1 in the second state. Specifically, as described with reference to FIGS. 3 and 4, by having one liquid crystal panel 20 (e.g., first liquid crystal panel 20A) provided as an E-mode liquid crystal panel and one liquid crystal panel 20 (e.g., second liquid crystal panel 20B) provided as an O-mode liquid crystal panel, it is possible to more reliably suppress the visibility of the image DSP from the other side in the first direction X for the display device 1 in the second state.

[0065] 11 and 12 are graphs showing the normalized transmittance of the display device 1 in the second state for each of E mode only, O mode only, and a combination of E mode and O mode. "E mode" indicates E mode only, i.e., the case where the light control unit 10 is configured to have only an E mode liquid crystal panel. "O mode" indicates O mode only, i.e., the case where the light control unit 10 is configured to have only an O mode liquid crystal panel. "E+O mode" indicates a combination of E mode and O mode, i.e., the case where the light control unit 10 is configured to have both E mode and O mode liquid crystal panels as in the embodiment.

[0066] Normalized transmittance is a value that represents the brightness of the image DSP that can be seen by the user, where the brightness of the image at the viewing angle at which the brightest image can be seen when the display device 1 is operating is set to 1.0, and the state in which there is no light from the light source 60 (when the display device 1 is not operating) is set to 0.0, and takes a value within the range of 0.0 to 1.0.

[0067] In FIG. 11 and FIGS. 28 and 30 (to be described later), the normalized transmittance is shown at equal intervals along the vertical axis from 0.00 to 1.00. In FIG. 12 and FIGS. 29 and 31 (to be described later), the top of the vertical axis is 1.0, and the normalized transmittance value decreases by 1 / 10 for each division down the vertical axis. FIGS. 11 and 12 differ only in the way they express the vertical axis, but the relationship between the viewing angle and the normalized transmittance is the same. In FIGS. 11 and 12 and FIGS. 28 to 31 (to be described later), the horizontal axis is shown with the line of sight from a frontal view of the display device 1 as the reference (a viewing angle of 0°), with a line of sight from an angle tilted to one side of the first direction X representing a positive (+) viewing angle and a line of sight from an angle tilted to the other side of the first direction X representing a negative (-) viewing angle.

[0068] If the light control unit 10 were configured to have only an E-mode liquid crystal panel, the normalized transmittance would be extremely close to 0 at a viewing angle of -30°, while the normalized transmittance would be 0.1 or more at viewing angles more positive (+) than -20° and more negative (-) than -40°. Thus, with only the E-mode, even a slight deviation from the viewing angle of -30° could leave the possibility that the image DSP could be unintentionally visible, even with squint.

[0069] On the other hand, when the light control unit 10 has only an O-mode liquid crystal panel, the normalized transmittance is generally 0.1 or more up to about -25° even from the other side of the first direction X. In this way, with only the O-mode, there is a possibility that suppression of visibility from the other side of the first direction X may be insufficient.

[0070] In contrast to these, when the light control unit 10 is configured to have both E-mode and O-mode liquid crystal panels as in the embodiment, the normalized transmittance becomes significantly less than 0.1 when the viewing angle is more negative than -20°. Moreover, unlike the case of only the E-mode, the normalized transmittance does not become 0.1 or more even when the viewing angle is more negative (-) than -40°. As such, according to the embodiment, since the light control unit 10 is configured to have both E-mode and O-mode liquid crystal panels, it is possible to more reliably suppress the visibility of the image DSP from the other side in the first direction X with respect to the display device 1 in the second state.

[0071] Next, the color shift tendency of the light control unit 10 in the first direction will be described with reference to Fig. 13 to Fig. 25. The color shift tendency here refers to the tendency of apparent color change caused by differences in the attenuation rate for each wavelength (or wavelength band) of light when light passes through the light control unit 10.

[0072] FIG. 13 is a graph showing the color shift tendency in the first direction for the first liquid crystal panel 20A. FIG. 14 is a graph showing the color shift tendency in the first direction for the second liquid crystal panel 20B. Note that FIGS. 13 and 14 illustrate the color shift tendency in the first direction by showing the relationship between brightness (L), chromaticity x, chromaticity y, and polar angle. Here, brightness (L) refers to the brightness generated on the image display side (transmission destination) when light passes through a liquid crystal panel such as the first liquid crystal panel 20A or the second liquid crystal panel 20B. The brightness (L) value is expressed as a ratio of the brightness of light before passing through the liquid crystal panel, with 0 (completely non-transmitting) being the minimum value and 1 (completely transmitting) being the maximum value. Chromaticity x is the degree of color perceived as red by humans based on the combination of hue and saturation. The higher the value, the more intense the red color can be reproduced. Chromaticity y is the degree to which a color is perceived as green by humans, based on a combination of hue and saturation; the higher the value, the more intense the red that can be reproduced. The lower the chromaticity x and y, the closer the reproducible color will be to blue. In other words, if the chromaticity x and y are sufficiently high, not only blue but also red and green can be reproduced satisfactorily.

[0073] As shown in Figure 13, the chromaticity x of the first liquid crystal panel 20A is generally within the range of 0.34 to 0.36 when the first directional polar angle is within the range of -20° to 20°. In some areas when the first directional polar angle is within the range of -10° to 5°, the chromaticity x slightly exceeds 0.36, but is within the range of 0.365 or less and does not significantly deviate from 0.36. Furthermore, the chromaticity y of the first liquid crystal panel 20A is within the range of 0.32 to 0.34 when the first directional polar angle is within the range of -20° to 20°.

[0074] 14, the chromaticity x of the second liquid crystal panel 20B is within a range of approximately 0.32 to 0.34 when the first directional polar angle is within a range of -20° to 20°. The chromaticity y of the second liquid crystal panel 20B is within a range of approximately 0.34 to 0.36 when the first directional polar angle is within a range of -20° to 20°. In some areas when the first directional polar angle is within a range of -5° to 5°, the chromaticity x is slightly below 0.34, but this is very slight and does not significantly deviate from 0.34.

[0075] 13 and 14, the difference in magnitude between the x chromaticity and the y chromaticity is reversed between the first liquid crystal panel 20A and the second liquid crystal panel 20B. Therefore, the balance between the x chromaticity and the y chromaticity is maintained by the light output from the display device 1 of the embodiment passing through both the first liquid crystal panel 20A and the second liquid crystal panel 20B.

[0076] 13 and 14, the brightness (L) of the first liquid crystal panel 20A and the second liquid crystal panel 20B is significantly lower in the negative polar angle range than in the positive polar angle range. Furthermore, in the negative polar angle range, the brightness (L) tends to decrease as the angle difference from a polar angle of 0° increases. This is due to the fact that the panels are configured so that the degree of light transmission on the negative viewing angle side is relatively lower than that on the positive viewing angle side, as explained with reference to FIGS. 7 to 9 and 11 and 12.

[0077] Figure 15 is a graph showing the difference between an embodiment of a display device 1 equipped with a dimming unit 10 including a first liquid crystal panel 20A and a second liquid crystal panel 20B as described with reference to Figures 13 and 14, and a comparative example in which the color shift tendency in the first direction is not particularly taken into consideration.

[0078] 15, the chromaticity x of the display device 1 of the embodiment is generally within a range of approximately 0.32 to 0.34 when the first direction polar angle is within a range of -20° to 20°. In some cases when the first direction polar angle is within a range of -20° to -15°, the chromaticity x is slightly below 0.32, but is within a range of 0.315 or greater and does not significantly deviate from 0.32. Furthermore, the chromaticity y of the display device 1 of the embodiment is within a range of approximately 0.34 to 0.36 when the first direction polar angle is within a range of -20° to 20°.

[0079] In contrast, in a comparative example that does not take into consideration the color shift tendency in the first direction, chromaticity x is significantly lower at a first direction polar angle of 10° on the negative side, and chromaticity y is significantly lower at a first direction polar angle of 5° on the negative side compared to the positive side, and the chromaticity x and chromaticity y decrease as the first direction polar angle becomes more negative. In this comparative example, a significant color difference is perceived between the positive and negative sides of the first direction polar angle.

[0080] 13 to 15, the retardation values ​​(Δnd) of the first liquid crystal panel 20A and the second liquid crystal panel 20B are determined in advance. That is, the first liquid crystal panel 20A and the second liquid crystal panel 20B are each configured to correspond to the predetermined Δnd.

[0081] Hereinafter, two factors that determine the retardation value (Δnd) of a liquid crystal panel such as the first liquid crystal panel 20A or the second liquid crystal panel 20B will be described with reference to FIGS.

[0082] FIG. 16 is a schematic diagram illustrating the relationship between the orientation of the liquid crystal LM and the retardation value (Δnd). In FIG. 16, the liquid crystal molecules contained in the liquid crystal LM are designated as liquid crystal molecules LM1. In a liquid crystal panel 20 such as the first liquid crystal panel 20A or the second liquid crystal panel 20B, the magnitude of Δnd can be adjusted by adjusting the tilt direction and magnitude of the long axis direction LX of the liquid crystal molecules LM1 relative to the third direction Z. In FIG. 16, the tilt direction Vp denotes the direction of tilt to one side relative to the third direction Z, and the tilt direction Vm denotes the direction of tilt to the opposite side of the tilt direction Vp across the third direction Z. Based on the retardation value (Δnd) of the liquid crystal panel 20 when the relationship between the long axis direction LX and the third direction Z shown in FIG. 16 is established, the retardation value (Δnd) increases as the long axis direction LX tilts toward the tilt direction Vp relative to the third direction Z. Furthermore, when the retardation value (Δnd) of the liquid crystal panel 20 when the long axis direction LX is aligned with the third direction Z is used as a reference, the retardation value (Δnd) decreases as the long axis direction LX is tilted toward the tilt direction Vm with respect to the third direction Z. In this way, the retardation value (Δnd) of the liquid crystal panel 20 can be adjusted by controlling the orientation of the liquid crystal molecules LM1.

[0083] Fig. 17 is a diagram schematically illustrating the relationship between the fast axis and slow axis of a retardation-generating structure and the thickness of the structure. Fig. 17 illustrates an example in which polarized light LVp emitted from a light source 501 passes through an optical member 502 that generates retardation and becomes polarized light LVq, which is different from the polarized light LVp.

[0084] The optical element 502 functions as an optical element in which the traveling speed of light passing from the light source 501 side to the opposite side differs between the fast axis Ny and the slow axis Nx. The fast axis Ny is the direction in which light travels faster than the slow axis Nx. Assume that polarized light LVp enters the optical element 502 from the light source 501 side, which has such a relationship between the fast axis Ny and the slow axis Nx. Here, the polarization direction of the polarized light LVp is assumed to be inclined with respect to both the fast axis Ny and the slow axis Nx. In this case, the light component along the fast axis Ny, which has a relatively faster traveling speed, travels toward the opposite side of the light source 501 ahead of the polarized light LVp, while the light component along the slow axis Nx, which has a relatively slower traveling speed, travels toward the opposite side of the light source 501 behind the polarized light LVp. As a result, in the polarized light LVq after passing through the optical element 502, a phase difference Ret occurs between the light component along the fast axis Ny and the light component along the slow axis Nx. The magnitude of the phase difference Ret corresponds to the retardation value (Δnd).

[0085] The greater the thickness of the optical member 502 in the direction perpendicular to the fast axis Ny and the slow axis Nx, the greater the phase difference Ret. In other words, a configuration that generates retardation, such as the optical member 502, can adjust the retardation value (Δnd) by adjusting the thickness corresponding to the propagation direction of the light passing through. More specifically, the retardation value (Δnd) is determined by the product of the difference between the fast axis Ny and the slow axis Nx (refractive index difference Δn) and the thickness (d).

[0086] In a liquid crystal panel 20 such as the first liquid crystal panel 20A or the second liquid crystal panel 20B, the retardation value (Δnd) can be set to a desired value by combining the tilt direction and magnitude of the long axis direction LX of the liquid crystal molecules LM1 with the cell gap in the third direction Z of the liquid crystal panel 20. More specifically, the refractive index difference Δn corresponding to the relationship between the fast axis Ny and the slow axis Nx in FIG. 17 is determined by the tilt direction and magnitude of the long axis direction LX of the liquid crystal molecules LM1. Furthermore, the cell gap in the third direction Z of the liquid crystal panel 20 functions as a thickness (d) by which the refractive index difference Δn is multiplied. The cell gap in the third direction Z of the liquid crystal panel 20 is the thickness of the liquid crystal LM in the third direction Z.

[0087] FIG. 18 is a graph illustrating an example of a method for setting the retardation value (Δnd). When determining the retardation value (Δnd) of each of the first liquid crystal panel 20A and the second liquid crystal panel 20B, it is desirable to use light of a specific wavelength as a reference. By using such a reference, the retardation value (Δnd) can be more clearly determined. FIG. 18 illustrates an example in which the retardation value (Δnd) of the first liquid crystal panel 20A is determined using the D-line as a reference. The D-line is light with a wavelength (approximately 589 nm) corresponding to the emission spectrum of sodium atoms and can be generated using a sodium lamp. In the first liquid crystal panel 20A of the embodiment, the combination of the tilt direction and magnitude of the long axis direction LX of the liquid crystal molecules LM1 during operation and the cell gap is adjusted so that the retardation value (Δnd) when the D-line passes through in the third direction Z is 1800 nm. For example, when the refractive index difference Δn of the first liquid crystal panel 20A during operation is 0.2, the cell gap of the first liquid crystal panel 20A is set to 9 μm (=9000 nm).

[0088] The retardation value (Δnd) of the second liquid crystal panel 20B is also determined using the same concept as the retardation value (Δnd) of the first liquid crystal panel 20A described with reference to Fig. 18. In the first liquid crystal panel 20A of the embodiment, the combination of the tilt direction and tilt magnitude of the long axis direction LX of the liquid crystal molecules LM1 during operation of the second liquid crystal panel 20B and the cell gap is adjusted so that the retardation value (Δnd) when the D line passes through in the third direction Z is 2800 nm or 3000 nm, for example.

[0089] When the retardation values ​​(Δnd) of the first liquid crystal panel 20A and the second liquid crystal panel 20B are determined as in the example described above, the first liquid crystal panel 20A and the second liquid crystal panel 20B are each provided as liquid crystal panels 20 having different cell gaps but the same other physical configurations.

[0090] Color reproduction achieved by the retardation values ​​(Δnd) of the first liquid crystal panel 20A and the second liquid crystal panel 20B described with reference to FIGS. 16 to 18 will be described with reference to FIGS. 19 to 25.

[0091] FIG. 19 is a graph schematically illustrating the relationship between the light transmittance and the color of light of each of the first liquid crystal panel 20A and the second liquid crystal panel 20B. The light transmittance of each of the first liquid crystal panel 20A and the second liquid crystal panel 20B varies depending on the color of the light, i.e., the wavelength of the light. In FIG. 19, transmittance Rop1 indicates the transmittance of red light transmitted through the first liquid crystal panel 20A. Transmittance Gop1 indicates the transmittance of green light transmitted through the first liquid crystal panel 20A. Transmittance Bop1 indicates the transmittance of blue light transmitted through the first liquid crystal panel 20A. Transmittance Rop2 indicates the transmittance of red light transmitted through the second liquid crystal panel 20B. Transmittance Gop2 indicates the transmittance of green light transmitted through the second liquid crystal panel 20B. Transmittance Bop2 indicates the transmittance of blue light transmitted through the second liquid crystal panel 20B.

[0092] The two arrows for the transmittances Rop2, Gop2, and Bop2 illustrate the cases where the retardation value (Δnd) of the second liquid crystal panel 20B is 2800 nm and 3000 nm. The arrow with the relatively smaller retardation value (Δnd) indicates the case of 2800 nm, and the arrow with the relatively larger retardation value (Δnd) indicates the case of 3000 nm.

[0093] The transmittance Gop1 is relatively higher than the transmittance Rop1 and the transmittance Bop1. Therefore, the first liquid crystal panel 20A transmits green light more easily than red light and blue light. On the other hand, the transmittance Gop2 is relatively lower than the transmittance Rop2 and the transmittance Bop2. Therefore, the second liquid crystal panel 20B transmits red light and blue light more easily than green light.

[0094] In the embodiment, overlapping the first liquid crystal panel 20A and the second liquid crystal panel 20B in the third direction Z makes it easier to achieve a more uniform balance between red light, green light, and blue light in the light emitted from the display device 1. That is, by individually determining the cell gaps of the two liquid crystal cells of the first liquid crystal panel 20A and the second liquid crystal panel 20B so as to correspond to the respective retardation values ​​(Δnd), and by providing characteristics such that the color shifts of the three primary colors of red, green, and blue are in opposite directions in the first liquid crystal panel 20A and the second liquid crystal panel 20B, it is possible to suppress color shifts by performing color compensation between the two panels when the first liquid crystal panel 20A and the second liquid crystal panel 20B are stacked.

[0095] Furthermore, even if the first liquid crystal panel 20A has a relatively small retardation value (Δnd) among the first and second liquid crystal panels 20A and 20B, a retardation value (Δnd) of 1800 nm can more reliably suppress bias in the reproduced colors due to color shifts of the three primary colors of red, green, and blue. This is because, in the range where the retardation value (Δnd) is smaller than the first value BL1 in FIG. 19, the degree of change in transmittance due to changes in the retardation value (Δnd) is rapid, and differences in the transmittance of red, green, and blue light due to light of different wavelengths are likely to occur. On the other hand, the first liquid crystal panel 20A and the second liquid crystal panel 20B, whose retardation value (Δnd) is 1800 nm or greater, can balance the transmittance of red, green, and blue light based on the relationship between the retardation value (Δnd) and light transmittance in the range where the retardation value is equal to or greater than the second value BL2. The relationship between the retardation value (Δnd) and the light transmittance in the range equal to or greater than the second value BL2 is such that the degree of change in the transmittance with the change in the retardation value (Δnd) is smaller than that in the range where the retardation value (Δnd) is smaller than the first value BL1. The second value BL2 is significantly larger than the first value BL1 and is at or near 1800 nm.

[0096] Fig. 20 is a graph showing the relationship between the cell gap of liquid crystal panel 20 and the transmittance of light passing through liquid crystal panel 20 in the third direction Z when the refractive index difference Δn is 0.2. Fig. 21 is a graph showing the relationship between the retardation value (Δnd) of liquid crystal panel 20 and the transmittance of light passing through liquid crystal panel 20 in the third direction Z. Each of the graphs for "450", "550", and "650" in Figs. 20 and 21 is a graph showing the transmittance of light at the wavelength (unit: nm) indicated by the numerical value.

[0097] As shown in Figure 20, in a TN liquid crystal panel such as liquid crystal panel 20, when the cell gap is 7 μm or greater, the transmittance tends to be stable at 0.95 or greater, regardless of whether the light wavelength is 450 nm (close to red), 650 nm (close to blue), or 550 nm (in between). In particular, in a TN liquid crystal panel such as liquid crystal panel 20, when the cell gap is 12 μm or greater, the transmittance becomes more stable, significantly closer to 1 than 0.95, regardless of whether the light wavelength is 450 nm (close to red), 650 nm (close to blue), or 550 nm (in between). Therefore, it is desirable to set the cell gap of at least one of first liquid crystal panel 20A and second liquid crystal panel 20B to 12 nm or greater.

[0098] 21, in a TN liquid crystal panel such as liquid crystal panel 20, once the retardation value (Δnd) exceeds approximately 1200 nm, the transmittance tends to stabilize at 0.95 or greater, regardless of whether the light wavelength is 450 nm (closer to red), 650 nm (closer to blue), or 550 nm (in between). In particular, in a TN liquid crystal panel such as liquid crystal panel 20, once the retardation value (Δnd) exceeds 2400 nm, the transmittance becomes more stable at a value significantly closer to 1 than 0.95, regardless of whether the light wavelength is 450 nm (closer to red), 650 nm (closer to blue), or 550 nm (in between). Therefore, it is desirable to set the retardation value (Δnd) of at least one of first liquid crystal panel 20A and second liquid crystal panel 20B to 2400 nm or greater.

[0099] FIG. 22 is a graph showing the relationship between the first-direction polar angle of the display device 1 from a user viewing the output of the display device 1 and the transmittance of chromaticity x for each cell gap of the first liquid crystal panel 20A. FIG. 23 is a graph showing the relationship between the first-direction polar angle of the display device 1 from a user viewing the output of the display device 1 and the chromaticity y for each cell gap of the first liquid crystal panel 20A. FIG. 24 is a graph showing the relationship between the first-direction polar angle of the display device 1 from a user viewing the output of the display device 1 and the chromaticity x for each cell gap of the second liquid crystal panel 20B. FIG. 25 is a graph showing the relationship between the first-direction polar angle of the display device 1 from a user viewing the output of the display device 1 and the chromaticity y for each cell gap of the second liquid crystal panel 20B. Chromaticity x and chromaticity y are as described above with reference to FIG. 13. 22, 23, 24, and 25 show graphs "3," "4," "5," "6," "7," "8," "9," "10," "11," "12," "13," "14," and "15." The numbers attached to each of these graphs indicate the cell gap value (unit: nm).

[0100] 22 to 25, when the cell gap of both the first liquid crystal panel 20A and the second liquid crystal panel 20B is 12 nm, the chromaticity x at a first-direction polar angle of 0° stabilizes at approximately 0.33, and the chromaticity y at a first-direction polar angle of 0° stabilizes at approximately 0.35. Furthermore, when comparing the range of cell gaps exceeding 12 nm with the range of cell gaps less than 12 nm, the degree of color shift (decrease in value) of both chromaticity x and chromaticity y due to changes in the first-direction polar angle is relatively gradual in the range of cell gaps exceeding 12 nm. Therefore, as described above, it is desirable to set the cell gap of at least one of the first liquid crystal panel 20A and the second liquid crystal panel 20B to 12 nm or greater.

[0101] In this embodiment, the refractive index difference Δn of both the first liquid crystal panel 20A and the second liquid crystal panel 20B is 0.2. The first liquid crystal panel 20A in E mode is manufactured with a cell gap of 9 μm (=9000 nm) so that the retardation value (Δnd) is 1800 nm. The first liquid crystal panel 20A in O mode is manufactured with a cell gap of 14 μm (=14000 nm) or 15 μm (=15000 nm) so that the retardation value (Δnd) is 2800 nm or 300 nm.

[0102] Both the first liquid crystal panel 20A and the second liquid crystal panel 20B may have a cell gap of 12 μm or more. Essentially, one of the first liquid crystal panel 20A and the second liquid crystal panel 20B may have a relatively high green light transmittance compared to the red light transmittance and the blue light transmittance, and the other of the first liquid crystal panel 20A and the second liquid crystal panel 20B may have a relatively low green light transmittance compared to the red light transmittance and the blue light transmittance, thereby canceling out the color shift. If the first liquid crystal panel 20A and the second liquid crystal panel 20B are configured to cancel out the color shift in this manner, the first liquid crystal panel 20A may be in O mode and the second liquid crystal panel 20B may be in E mode. Alternatively, the first liquid crystal panel 20A and the second liquid crystal panel 20B may be in E mode, or the first liquid crystal panel 20A and the second liquid crystal panel 20B may be in O mode.

[0103] In the display device 1, the specific configuration of the display panel 30 that can be combined with the light control unit 10 of the embodiment is not limited to the IPS liquid crystal panel described above. The display panel 30 may be of another type as long as it is a so-called transmissive liquid crystal panel having a plurality of pixels that can individually control the degree of light transmission in response to input image data from outside. The following describes the configuration of pixels provided in an IPS liquid crystal panel that can be used as the display panel 30 of the embodiment with reference to FIG. 26.

[0104] FIG. 26 is a plan view showing an example of a pixel layout in the display panel 30. FIG. 26 shows the overlap between the pixel electrodes PE1, PE2 and the common electrode CE when viewed from the fifth polarizing layer 42 side. The pixel electrode P described with reference to FIG. 2 is the pixel electrode PE1 or the pixel electrode PE2 in FIG. 26. The pixel substrate 31 includes a plurality of scanning lines G and a plurality of signal lines S. The plurality of scanning lines G each extend along the first direction X and are arranged at intervals in the second direction Y. The plurality of signal lines S each extend approximately along the second direction Y and are arranged at intervals in the first direction X.

[0105] The plurality of pixel electrodes PE1 are aligned along the first direction X. Each pixel electrode PE1 has a charging electrode Pa1 overlapping the common electrode CE. The charging electrode Pa1 extends along a direction D1 different from the first direction X and the second direction Y. The plurality of pixel electrodes PE2 are aligned along the first direction X. Each pixel electrode PE2 has a charging electrode Pa2 overlapping the common electrode CE. The charging electrode Pa2 extends along a direction D2 different from the direction D1. The number of charging electrodes Pa1 and Pa2 may be one, or three or more.

[0106] The display device 1 according to the embodiment has been described above with reference to Fig. 1 to Fig. 26. Modifications of the embodiment will now be described with reference to Fig. 26 to Fig. 33.

[0107] (Variation 1) In the embodiment, the rubbing directions of one of the two alignment films (alignment film 23a and alignment film 24a) facing each other across the liquid crystal LM in the liquid crystal panel 20 differ by 90°. That is, although the twist angle of the liquid crystal panel 20 is 90° in the embodiment, the twist angle of the liquid crystal panel 20 is not limited to this. For example, the twist angle of the liquid crystal panel 20 may be less than 90°. Furthermore, the twist angle of the liquid crystal panel 20 provided as an O-mode liquid crystal panel (e.g., the second liquid crystal panel 20B) may be smaller than the twist angle of the liquid crystal panel 20 provided as an E-mode liquid crystal panel (e.g., the first liquid crystal panel 20A). Hereinafter, the relationship between the twist angle and the optical characteristics of the liquid crystal panel 20 will be described with reference to FIGS. 27 to 31.

[0108] Fig. 27 is a graph showing the relationship between the polar angle and the light transmittance when liquid crystal panel 20 provided as an E-mode liquid crystal panel is operating (ON) for each of the cases where the twist angle is 90° (twist 90°) and where the twist angle is 80° (twist 80°). Figs. 28 and 29 are graphs showing the normalized transmittance on one side and the other side in the first direction X when liquid crystal panel 20 provided as an E-mode liquid crystal panel is operating (ON) for each of the cases where the twist angle is 90° (twist 90°) and where the twist angle is 80° (twist 80°).

[0109] 27, in the case of E mode, when the twist angle is 90°, within the range of polar angles from 0° to approximately 25° or more and less than 30°, the degree of decrease in transmittance as the polar angle increases is steeper than when the twist angle is 80°. Therefore, as shown in FIGS. 28 and 29, for liquid crystal panel 20 provided as an E mode liquid crystal panel, within the polar angle range from 0° to approximately 25° or more and less than 30°, that is, within the viewing angle range on the positive side of a viewing angle of −30°, a twist angle closer to 90° tends to be preferable to a configuration with a twist angle of 80° in that the normalized transmittance decreases more favorably as the viewing angle approaches the other side in first direction X.

[0110] On the other hand, in the case of liquid crystal panel 20 provided as an E-mode liquid crystal panel, when the twist angle is 90°, the transmittance becomes higher when the polar angle exceeds 30° compared to when the twist angle is 80°. For this reason, it is desirable to use other means to lower the normalized transmittance in the negative (-) viewing angle range of -30° or less.

[0111] 30 and 31 are graphs showing the normalized transmittance on one side and the other side in the first direction X when the twist angle is 90° (twist 90°) and when the twist angle is 80° (twist 80°) and when the liquid crystal panel 20 is operated (ON) as an O-mode liquid crystal panel. As shown in FIGS. 30 and 31, in the O-mode, when the twist angle is 80°, the transmittance is almost the same as or lower than when the twist angle is 90° within the polar angle range from 0° to approximately 35°. Furthermore, in the O-mode, when the polar angle is 40° or more, the transmittance is significantly lower at a twist angle of 80° than at a twist angle of 90°, and a nearly stable transmittance is obtained. Therefore, for the liquid crystal panel 20 provided as an O-mode liquid crystal panel, a twist angle of 80° can ensure a sufficiently low normalized transmittance in the viewing angle range on the positive (-) side, with a viewing angle of -40° as the reference, and tends to obtain an even lower normalized transmittance in the viewing angle range on the negative (-) side.

[0112] Based on the respective tendencies of the E mode and the O mode described with reference to FIGS. 27 to 31, in Modification 1, as described above, the twist angles of the first liquid crystal panel 20A and the second liquid crystal panel 20B of the dimming unit 10 are set so that the twist angle of the liquid crystal panel 20 (e.g., the second liquid crystal panel 20B) provided as the O mode liquid crystal panel is smaller than the twist angle of the liquid crystal panel 20 (e.g., the first liquid crystal panel 20A) provided as the E mode liquid crystal panel. As a specific example of the twist angle in Modification 1, the twist angle of the first liquid crystal panel 20A is set to 90° or an angle closer to 90° even if it is less than 90°. Furthermore, in this specific example, the twist angle of the second liquid crystal panel 20B is set to 80°. This more reliably achieves both the steeper shading cutoff characteristics on the other side of the first direction X in the E mode and the wider shading viewing angle range in the O mode.

[0113] In addition, since the twist angle in Modification 1 is different from that of the embodiment, the transmission axis directions V05 and V07 (see FIG. 3) are also set to angles corresponding to the twist angle of Modification 1. Furthermore, by making the slow axis direction V08 of the retardation generation layer 52 larger (for example, about -27.5° to -28°), it is possible to achieve transmission of light through the transmission path LV, as in the embodiment, even when the specific example of the twist angle in Modification 1 described above is adopted. Of course, it is also possible to achieve transmission of light through the transmission path LV by making polarization-related characteristics other than the slow axis direction V08 correspond to Modification 1, such as by adjusting the transmission axis direction V09 and the transmission axis direction V11.

[0114] (Variation 2) 32 is a schematic diagram showing an example of the main configuration of a display device 1A according to Modification 2. The display device 1A is similar to the display device 1 according to the embodiment (see FIG. 1) except that the retardation generating layer 51 is omitted from the configuration of the display device 1 according to the embodiment and except for matters relating to the polarization angle of the polarized light generating layer 53, which will be noted below.

[0115] In the embodiment, the phase difference generating layer 51 is provided, but by changing the polarization angle of the polarization generating layer 53, which in the embodiment is set to polarize the light emitted from the other surface of the light source 60 at 0° and transmit it, the phase difference generating layer 51 can be omitted as shown in Fig. 32. The polarization angle of the polarization generating layer 53 in the second modification will be described below with reference to Fig. 33.

[0116] FIG. 33 is a schematic diagram showing polarization axis directions V21, V22, which are examples of polarization angles of the polarization generating layer 53 that can be employed in Modification 2, and angle ranges R21, R22 within which the polarization angles can be set. For example, consider a configuration in which light LS3 from the display device 1 is reflected to generate light LS4, as in the reflector 102 shown in FIG. 8. In this case, light LS4 reaching the user U2 may unintentionally cause the image DSP output by the display device 1 in the second state to be visible to the user U2. In this case, for example, if FIG. 8 shows an example of the interior of a four-wheeled vehicle, the passenger-side side window may function as the reflector 102, thereby achieving this.

[0117] Therefore, in Modification 2, the polarization angle of the polarization generating layer 53 is determined so as to make it more difficult to generate the light LS3. Specifically, when making it more difficult to generate the light LS3 in the relationship between the display device 1 and the user U2 shown in FIG. 8, the polarization angle is determined along the XY plane and in a direction intersecting the first direction X and the second direction Y, as in the polarization axis direction V22 of FIG. 33. More specifically, in this case, the polarization generating layer 53 of Modification 2 has the polarization axis direction V22 determined so as to transmit light emitted from the other surface of the light source 60 as polarized light at +135°. In this case, the light transmission path LV does not exist from the slow axis direction V02 to the transmission axis direction V11 in the embodiment described with reference to FIG. 3. However, by reversing the relationship between one side of the first direction X and the other side of the first direction X in the description of polarization described with reference to FIG. 3, the light transmission path LV can also be established in this case. Due to this polarization axis direction V22, the light emitted from the light source 60 and transmitted through the polarization generation layer 53 exhibits an elliptical light spread as shown in light region L22. The relationship between the major axis of the ellipse shown as light region L22 in Figure 33, the minor axis of the ellipse, and the polarization axis direction V22 is such that the acute angle between the major axis and the polarization axis direction V22 is smaller than the acute angle between the minor axis and the polarization axis direction V22. This elliptical spread of light suppresses the generation of light LS3 traveling from the display device 1 toward the reflector 102 in Figure 8.

[0118] If the user U2 shown in FIG. 8 is a driver of a four-wheeled vehicle, the steering wheel of the four-wheeled vehicle is located at or near the position of the component 101 facing the user U2 in the third direction Z. That is, if FIG. 8 is an example of the interior of a four-wheeled vehicle, this example is an example of a left-hand drive. In the case of a right-hand drive vehicle, the positional relationship between the display device 1 and the component 101 is reversed. That is, in this case, the user U2 views the display device 1 from the front, and the user U1 views the component 101 obliquely from one side in the first direction X. In this case, for example, by rotating the retardation generating layer 51, the dimming unit 10, and the retardation generating layer 52 of the components of the display device 1 by 180 degrees about the third direction Z as the rotation axis relative to the other components, the relationship between one side in the first direction X and the other side in the first direction X in the description with reference to FIG. 7 can be reversed, and the relationship between the front view and the oblique view shown in FIG. 9 can be similarly realized. That is, the display device 1 can appropriately set the orientation relationship between "one side of the first direction X and the other side of the first direction X" in the description with reference to Fig. 7 depending on the physical orientation of the liquid crystal panel 20. Furthermore, in the case of a right-hand drive vehicle, the above-mentioned "state in which the image DSP output by the display device 1 in the second state is also visible to the user U2" may be unintentionally achieved by the reflector 103 on the user U2 side, instead of the reflector 102 on the user U1 side in the case of a left-hand drive vehicle.

[0119] In the case of a right-hand drive vehicle, the polarization generating layer 53 of Modification 2 has a polarization axis direction V21 determined so as to transmit light emitted from the other surface of the light source 60 as polarized light at +45°. In this case, a light transmission path LV is established by a configuration in which the phase difference generating layer 51 is removed from the embodiment described with reference to FIG. 3. With such a polarization axis direction V21, the light emitted from the light source 60 and transmitted through the polarization generating layer 53 exhibits an elliptical light spread, such as light region L21, which differs from light region L22. The relationship between the major axis of the ellipse shown as light region L21 in FIG. 33, the minor axis of the ellipse, and the polarization axis direction V21 is such that the acute angle between the major axis and the polarization axis direction V21 is smaller than the acute angle between the minor axis and the polarization axis direction V21.

[0120] The polarization axis of the polarization generating layer 53 in Modification 2 is not limited to polarization axis directions V21 and V22. For example, in the case of a right-hand drive vehicle, the polarization axis may be set within an angle range R21 of -15° to +105°. In addition, in the case of a left-hand drive vehicle, the polarization axis may be set within an angle range R22 of +75° to +195°. However, even within the angle ranges R21 and R22, it is preferable that the polarization axis not be aligned with the alignment direction of user U1 and user U2, i.e., the direction corresponding to the first direction X (0°, 180°). Note that a configuration that combines both Modifications 1 and 2 is also possible.

[0121] As described above, the display device (display device 1) includes a display panel (display panel 30) having a display area for outputting an image, a light source (light source 60) that emits light from one side of the display panel, and a dimming unit (dimming unit 10) that is interposed between the display panel and the light source and is capable of changing the degree of light transmission between the display panel and the light source. The dimming section has, from the light source side to the display panel side, a first polarizing layer (first polarizing layer 11), a first liquid crystal panel (first liquid crystal panel 20A), a second polarizing layer (second polarizing layer 12), a second liquid crystal panel (second liquid crystal panel 20B), and a third polarizing layer (third polarizing layer 13) stacked one on the other, and one of the first liquid crystal panel and the second liquid crystal panel has a relatively high transmittance for green light compared to the transmittance for red light and the transmittance for blue light (for example, transmittance Rop1, transmittance Gop1, transmittance Bop1 in Figure 19), and the other of the first liquid crystal panel and the second liquid crystal panel has a relatively low transmittance for green light compared to the transmittance for red light and the transmittance for blue light (for example, transmittance Rop2, transmittance Gop2, transmittance Bop2 in Figure 19). This allows the relative transmittances of red, green, and blue light in the dimming unit to be offset by the first liquid crystal panel and the second liquid crystal panel. In other words, the transmittances of red, green, and blue light, which contribute to color reproduction, can be made uniform in the dimming unit. Therefore, color bias caused by the dimming unit can be suppressed. Thus, according to the embodiment, color bias in the display output image by the display device can be further suppressed.

[0122] Furthermore, by setting the cell gap of at least one of the first liquid crystal panel (first liquid crystal panel 20A) and the second liquid crystal panel (second liquid crystal panel 20B) to 12 μm or more, the degree of color shift (decrease in value) caused by changes in the first direction polar angle can be further suppressed for both chromaticity x and chromaticity y. This makes it easier to suppress color bias in the image displayed and output by the display device.

[0123] Furthermore, by configuring one of the first and second liquid crystal panels (e.g., first liquid crystal panel 20A) as an E-mode liquid crystal panel and the other of the first and second liquid crystal panels (e.g., second liquid crystal panel 20B) as an O-mode liquid crystal panel, it is possible to realize image display output utilizing the advantages of both E-mode and O-mode liquid crystal panels. The advantage of an E-mode liquid crystal panel is a steep reduction in light transmittance for the ray of light at a specific angle (e.g., near a viewing angle of −30°). The advantage of an O-mode liquid crystal panel is a stable reduction in light transmittance over a wider range (e.g., on the negative (−) side of a viewing angle of −30°). Furthermore, both E-mode and O-mode panels can transmit enough light to make images visible, except for the viewing angle range where light transmittance is particularly reduced. Thus, according to the embodiment, it is possible to simultaneously establish a viewing angle range in which an image can be viewed and a viewing angle range in which an image cannot be viewed, while more reliably ensuring a wider viewing angle range in which an image cannot be viewed.

[0124] Furthermore, the first rubbing direction of one of the two alignment films (alignment films 23a, 24a) facing each other across the liquid crystal (liquid crystal LM) (alignment film 23a), which is disposed on the light source (light source 60) side, and the second rubbing direction of the other of the two alignment films (alignment film 24a), which is disposed on the display panel side, are common to the first liquid crystal panel (first liquid crystal panel 20A) and the second liquid crystal panel (second liquid crystal panel 20B). This makes it possible to prepare two identical liquid crystal panels (liquid crystal panels 20), one of which is an E-mode liquid crystal panel and the other an O-mode liquid crystal panel. This eliminates the need to separately manufacture the E-mode liquid crystal panel and the O-mode liquid crystal panel, allowing the display device of the embodiment to be provided as a display device with higher mass productivity and lower cost.

[0125] Furthermore, since the twist angle of the liquid crystal in an O-mode liquid crystal panel is smaller than that in an E-mode liquid crystal panel, the advantages of both the E-mode liquid crystal panel and the O-mode liquid crystal panel can be utilized to an even greater extent.

[0126] Furthermore, since the twist angle of the liquid crystal in the first liquid crystal panel (first liquid crystal panel 20A) and the second liquid crystal panel (second liquid crystal panel 20B) is less than 90°, the advantages of both the E-mode liquid crystal panel and the O-mode liquid crystal panel described above can be utilized to an even greater extent.

[0127] Furthermore, the display device (display device 1) is provided with a polarization generating layer (polarization generating layer 53) that is arranged between the light source (light source 60) and the dimming unit (dimming unit 10) and polarizes the light emitted from the light source in a specific direction, and the specific direction is a direction (e.g., polarization axis direction V21 or polarization axis direction V22) that intersects all four sides of the rectangular display area (display area AA), thereby making it easier to prevent unintended viewing of images by a reflector (e.g., reflector 102) that is located in the opposite position from the user who wants to prevent the image from being viewed through a squinting gaze.

[0128] Furthermore, when the first liquid crystal panel (first liquid crystal panel 20A) and the second liquid crystal panel (second liquid crystal panel 20B) are operating, the light control unit (display panel 30) differentiates the degree of light transmission inclined to one side in the longitudinal direction of the rectangular display panel (one side in the first direction X) from the degree of light transmission inclined to the other side in the longitudinal direction (the other side in the first direction X) based on the opposing direction (third direction Z) between the display panel (display panel 30) and the light source (light source 60). This makes it possible to simultaneously establish a viewing angle range in which an image is visible and a viewing angle range in which an image is not visible.

[0129] The positional relationship between the E-mode liquid crystal panel and the O-mode liquid crystal panel between the display panel (display panel 30) and the light source (light source 60) may be reversed from that in the embodiment. In this case, the relationship between the transmission axis direction and the absorption axis direction of each of the first polarizing layer 11, the second polarizing layer 12, and the third polarizing layer 13 may be reversed. Also, the directions of the slow axes V02 and V08 of the retardation generating layers 51 and 52 may be changed so that they are symmetrical with respect to the second direction Y.

[0130] Furthermore, other effects and advantages brought about by the aspects described in this embodiment that are clear from the description in this specification or that can be appropriately thought of by a person skilled in the art are naturally understood to be brought about by the present disclosure. [Explanation of symbols]

[0131] 1 Display device 10 Dimming section 11 First polarizing layer 12 Second polarizing layer 13 Third polarizing layer 20 LCD panel 20A 1st LCD panel 20B Second LCD panel 23a, 24a Alignment film 30 Display Panel 53 Polarization generation layer 60 light source

Claims

1. a display panel having a display area for outputting an image; a light source that irradiates light from one side of the display panel; a light control unit interposed between the display panel and the light source and configured to change the degree of light transmission between the display panel and the light source, The light control unit a first polarizing layer, a first liquid crystal panel, a second polarizing layer, a second liquid crystal panel, and a third polarizing layer are stacked in this order from the light source side to the display panel side; one of the first liquid crystal panel and the second liquid crystal panel has a relatively high transmittance for green light compared to a transmittance for red light and a transmittance for blue light; the other of the first liquid crystal panel and the second liquid crystal panel has a relatively low transmittance for green light compared to a transmittance for red light and a transmittance for blue light; Display device.

2. At least one of the first liquid crystal panel and the second liquid crystal panel has a cell gap of 12 μm or more. The display device according to claim 1 .

3. one of the first liquid crystal panel and the second liquid crystal panel is provided as an E-mode liquid crystal panel, and the other of the first liquid crystal panel and the second liquid crystal panel is provided as an O-mode liquid crystal panel; The display device according to claim 1 or 2.

4. a first rubbing direction of one of two alignment films disposed on the light source side of the two alignment films facing each other across the liquid crystal, and a second rubbing direction of the other of the two alignment films disposed on the display panel side of the two alignment films, the first liquid crystal panel and the second liquid crystal panel being common to each other; The display device according to claim 1 or 2.

5. The O-mode liquid crystal panel has a smaller twist angle of liquid crystal than the E-mode liquid crystal panel. The display device according to claim 3 .

6. The first liquid crystal panel and the second liquid crystal panel have a twist angle of the liquid crystal less than 90°. The display device according to claim 5 .

Images