Display device

Abstract

To provide a display device which can detect the operation state of a liquid crystal panel.SOLUTION: A display device 1 includes: a display panel 30 having a display region AA for outputting an image; a light source 60 for radiating light from one surface side of the display panel 30; a liquid crystal panel 20 arranged between the display panel 30 and the light source 60, the liquid crystal panel being capable of changing the degree of transmission of light between the display panel 30 and the light source 60; and a control unit for controlling the potential difference between two electrodes FE1, FE2 facing each other across the liquid crystal in the liquid crystal panel 20. The liquid crystal panel 20 in operation differentiates the degree of transmission of light which is inclined to one side in a first direction X to a third direction Z and the degree of transmission of light which is inclined to the other side. The potential difference corresponds to the angle of a lower inclination of the degree of transmission of light when the liquid crystal panel 20 is operating.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] There is a demand for limiting the viewing angle range in which an image can be viewed in a display device. For example, in a display device mounted on a vehicle such as a four-wheeled automobile, it is required to realize a viewing angle range in which an image can be viewed from the passenger seat, and the image cannot be viewed from the driver's seat only while driving. In order to realize such a viewing angle range, a technology has been proposed in which a liquid crystal panel for light control is superimposed on a panel for displaying an image (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-195388 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for a display device capable of limiting the viewing angle range in which an image can be viewed to be able to set the viewing angle range more flexibly. For example, the display device may be mounted on a plurality of types of four-wheeled automobiles. In the different types of four-wheeled automobiles, the positional relationship between the driver's seat and the display device may differ. There has been a demand for a display device capable of limiting the viewing angle range in which an image can be viewed in response to the positional relationship between the driver's seat and the display device of each of the plurality of types of four-wheeled automobiles. In addition, it is desirable to be able to more flexibly determine the viewing angle range in which an image can be viewed in any environment in which the display device can be installed, not limited to a four-wheeled automobile. It has been difficult for a conventional display device to meet such a demand.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a display device that allows for more flexible setting of the viewing angle range in which an image is viewable. [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, a liquid crystal panel interposed between the display panel and the light source so as to be able to change the degree of light transmission between the display panel and the light source, and a control unit for controlling the potential difference between two electrodes facing each other across liquid crystal in the liquid crystal panel, wherein, during operation, the liquid crystal panel differentiates the degree of light transmission inclined to one side of the longitudinal direction of the rectangular display panel from the degree of light transmission inclined to the other side of the longitudinal direction, based on the opposing direction between the display panel and the light source, and the potential difference corresponds to the angle of inclination at which the degree of light transmission is lower during operation of the liquid crystal panel. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing an example of a main configuration of a display device according to an embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view of each of the components of the display device. [Diagram 3] FIG. 3 is a diagram showing changes in the deflection direction of light that occur from the light source until it is emitted to the other surface side of the display device. [Figure 4] FIG. 4 is a diagram showing the relationship between the rubbing directions R6a, 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 arranged to face each other in the third direction across the second liquid crystal panel. [Diagram 5] FIG. 5 is a diagram showing the orientation of liquid crystal molecules when the liquid crystal panel is not in operation (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 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 / not operating (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 an image viewed by a user looking at the display device from the front and an image viewed by a user looking at 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 a display device in the second state for each of the E mode only, the O mode only, and a combination of the E mode and the O mode. [Figure 12] FIG. 12 is a graph showing the normalized transmittance of a display device in the second state for each of the E mode only, the O mode only, and a combination of the E mode and the O mode. [Figure 13] FIG. 13 is a plan view showing an example of a pixel layout in a display panel. [Figure 14] FIG. 14 is a diagram showing an example of the relationship between three viewing angles on the minus (-) side and the level of normalized transmittance. [Figure 15] FIG. 15 is a diagram showing an example of the relationship between three viewing angles on the minus (-) side and control of the normalized transmittance by controlling the voltage applied to the liquid crystal. [Figure 16] FIG. 16 is a graph showing an example of the normalized transmittance when the voltage applied to the liquid crystal is any one of 2 [V] to 2.7 [V] (in increments of 0.1 V). [Figure 17] FIG. 17 is a graph showing an example of the relationship between the voltage applied to the liquid crystal and the cut angle. [Figure 18] FIG. 18 is a schematic diagram showing an example of the positional and angular relationship between the display device and a seat on which a user who will view the image on the display device from an oblique angle is expected to sit. [Figure 19]FIG. 19 is a schematic diagram showing an example of a configuration in which a camera is used to identify the positional and angular relationship between a user and a display device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings. Note that the disclosure is merely an example, and those who are skilled in the art can easily come up with appropriate modifications while maintaining the gist of the invention are naturally included in the scope of the present disclosure. In addition, in order to make the explanation clearer, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual embodiment, but they are merely examples and do not limit the interpretation of the present disclosure. In addition, in this specification and each figure, elements similar to those described above with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0009] FIG. 1 is a schematic diagram showing a main configuration example 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. In addition, 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. In Fig. 2, there are gaps between the components of the light source 60, the retardation generating layer 51, the light control section 10, the retardation generating layer 52, and the display panel 30. The 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 light control 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 overlapped 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 later, are optical members provided to transmit polarized light in a specific direction most. The specific direction is referred to as a transmission axis direction. The transmission axis direction is along 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 an absorption axis direction. The absorption axis direction is a polarization direction in which light is least likely to transmit through 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 a device, except that they are provided at different positions. Hereinafter, when the liquid crystal panel 20 is described, it includes 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 commonly applied to the first liquid crystal panel 20A and the second liquid crystal panel 20B. The liquid crystal panel 20 of the embodiment is a so-called TN (Twisted Nematic) type 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 thereto, and may be a substrate made of other light-transmitting materials. Hereinafter, when "one side" is described, it refers to a surface on one side in the third direction Z in a plate-like configuration. Furthermore, when "the other side" is described, it refers to a surface on the other side in the third direction Z in a plate-like configuration.

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

[0015] At least one of the electrodes FE2 and FE1 is provided so that the potential can be changed depending on the ON / OFF state of the liquid crystal panel 20. That is, the voltage generated between the electrodes FE2 and FE1 differs between when the liquid crystal panel 20 is operating (ON) and when it is not operating (OFF).

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

[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 electrodes FE2 and FE1 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 of image data from the outside.

[0019] The display panel 30 shown in Fig. 2 is a so-called IPS (In Plane Switching) type liquid crystal panel. In the display panel 30, a pixel substrate 31 is provided on one side in the third direction Z with liquid crystal LQ sandwiched therebetween, and a counter substrate 32 is provided on the other side. Furthermore, a fourth polarizing layer 41 is provided on one surface side of the pixel substrate 31. A fifth polarizing layer 42 is provided on the other surface side of the counter substrate 32. Hereinafter, when the term "panel section DP" is used, it 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 side in the third direction Z. On one surface of the counter substrate 32, a color filter 35, etc. are laminated. 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 in 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 a plurality of pixel electrodes P are arranged. The plurality of pixel electrodes P are arranged two-dimensionally along the XY plane in the display area AA. The display panel 30 is a so-called active matrix type display panel that is provided so as to be capable of displaying and outputting any image by individually controlling the degree of light transmission in each pixel electrode P. More specifically, in the display panel 30 of the embodiment, a reference potential is applied to the common electrode CE. Furthermore, individual potentials (pixel signals) are applied to the plurality of pixel electrodes P, so that the degree of light transmission in each pixel electrode P is individually controlled. Therefore, the display area AA can be said to be an area where an image is displayed and output.

[0022] The retardation generating layer 51 and the retardation generating layer 52 are optical members 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 1 / 2 wavelength plates.

[0023] The light source 60 emits light toward the other surface on which the polarized light generating layer 53 is provided. The polarized light generating layer 53 is an optical member that polarizes the light emitted from the other surface of the light source 60 at a specific angle. The polarized light generating layer 53 is, for example, a DBEF (Dual Brightness Enhancement Film), but is not limited thereto, and may be configured to polarize 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 polarized light 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 deflection direction of light that occur before the 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 defined 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 the changes in the deflection direction of light, a change in counterclockwise rotation by r° along the XY plane is described as a "change of +r°", and a change in the opposite (clockwise) rotation by r° is described as a "change of -r°". r is a real number equal to or greater than 0.

[0026] In the 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 transmitted through the polarization generating layer 53 and incident on the phase difference generating layer 51 is 0° polarized light.

[0027] The retardation generating layer 51 is a half-wave plate as described above. The retardation generating layer 51 of the embodiment generates a change in the counterclockwise (+) direction. The retardation generating layer 51 has a slow axis direction V02 set to be +22.5° with respect to the polarized light (0°) transmitted through the polarized light generating layer 53. As a result, the polarized light is changed by +45° by transmitting through the retardation generating layer 51. Therefore, the polarized light transmitted through the retardation generating layer 51 and incident on 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 transmitted through the retardation generating layer 51.

[0028] The first polarizing layer 11 has a transmission axis direction V03 determined so as to transmit the maximum amount of 45° polarized light. Therefore, the light transmitted through the phase difference generation layer 51 can be transmitted through the first polarizing layer 11. Moreover, the polarized light transmitted through the first polarizing layer 11 and incident on the first liquid crystal panel 20A is polarized at 45°.

[0029] The liquid crystal panel 20 is provided so as to give a change of +90° to the polarized light transmitted from one side to the other side in the third direction Z. That is, a change of +90° occurs in the polarized light by transmitting through the first liquid crystal panel 20A. Therefore, the polarized light transmitted through the phase difference generating layer 51 and incident on the first polarizing layer 11 is polarized at 135°. FIG. 3 shows the angle V04b of the polarized light incident on the first liquid crystal panel 20A and the angle V04a of the polarized light transmitted through the first liquid crystal panel 20A.

[0030] The second polarizing layer 12 has a transmission axis direction V05 determined so as to transmit 135° polarized light to the maximum extent possible. Therefore, the light transmitted through the first liquid crystal panel 20A can transmit through the second polarizing layer 12. Moreover, the polarized light that transmits 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 changes by +90°. Therefore, the polarized light passing through the phase difference generating layer 51 and entering the first polarizing layer 11 can be said to be polarized at 225°, which is the same as the polarized light at 45°. FIG. 3 shows the angle V06b of the polarized light entering the second liquid crystal panel 20B and the angle V046 of the polarized light passing through the second liquid crystal panel 20B.

[0032] The third polarizing layer 13 has a transmission axis direction V07 determined so as to transmit 45° polarized light to the maximum extent. Therefore, the light transmitted through the second liquid crystal panel 20B can be transmitted through the third polarizing layer 13. Moreover, the polarized light transmitted through the third polarizing layer 13 and incident on the phase difference generating layer 52 is polarized at 45°.

[0033] The retardation generating layer 52 is a half-wave plate as described above. The retardation generating layer 52 of the embodiment generates a change in the clockwise (-) direction. The retardation generating layer 52 has a slow axis direction V08 set to be -22.5° with respect to the polarized light (45°) transmitted through the polarized light generating layer 53. As a result, the polarized light is changed by -45° when it passes through the retardation generating layer 52. 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 that enters the retardation generating layer 52 and the angle V08a of the polarized light that has passed through the retardation generating layer 52.

[0034] The fourth polarizing layer 41 has a transmission axis direction V09 determined so as to transmit 0° polarized light to the maximum extent. Therefore, the light transmitted through the phase difference generation layer 52 can be transmitted through the fourth polarizing layer 41. Moreover, the polarized light transmitted through the fourth polarizing layer 41 and incident on the panel unit DP is 0° polarized light.

[0035] The panel part DP is provided so as to impart a change of +90° to the polarized light transmitted from one side to the other side in the third direction Z. That is, a change of +90° occurs in the polarized light as it passes through the panel part DP. Therefore, the polarized light that passes through the panel part DP and enters the fifth polarizing layer 42 is polarized at 90°. FIG. 3 shows an angle V10b of the polarized light that enters the panel part DP and an angle V10a of the polarized light that has passed through the panel part 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, the light transmitted through the panel unit DP can transmit through the fifth polarizing layer 42. In this manner, a light transmission path LV from the light source 60 to the other surface side of the fifth polarizing layer 42 is established.

[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, R6b of the alignment films 23a, 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 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. The direction that forms an angle counterclockwise with respect to the 0° direction is defined as the plus (+) angle (°) direction, and the direction that forms an angle clockwise 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 in order to orient the liquid crystal molecules in a specific direction. The specific direction determined by the 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 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 is perpendicular to the alignment axis of the polarizing layer that abuts on the substrate, i.e., 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°) like the second liquid crystal panel 20B. Here, the transmission axis direction V3 of the first polarizing layer 11 arranged on one side with the first liquid crystal panel 20A sandwiched between them 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°) like the second liquid crystal panel 20B. The transmission axis direction V5 of the second polarizing layer 12 arranged on the other side with the first liquid crystal panel 20A sandwiched between them is 135°. From these, in the first liquid crystal panel 20A of the embodiment, the rubbing direction of the alignment film laminated on the substrate and the alignment axis of the polarizing layer abutting 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 spheroid shape. Here, the long axis direction of the elongated spheroid is defined as ne(n extraordinary ) axis. The short axis direction of the spheroid perpendicular to the ne axis is no(n 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 FIG. 5 and FIG. 6 described later, liquid crystal molecules LM2 are shown as liquid crystal molecules contained in the liquid crystal LM. 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 side 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 along 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 so that the long axis direction LX faces the Z direction side according to the potential difference between the electrodes FE2 and FE1 (see FIG. 2). Therefore, when the liquid crystal panel 20 is operating (ON), as shown in FIG. 6, the long axis direction LX of the liquid crystal molecules LM2 intersects the XY plane.

[0049] When the liquid crystal panel 20 is in a non-operating 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 a non-operating state (OFF), when the 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 the viewpoint in which the display device 1 is viewed from the front, the brightness of the image recognized at the two viewpoints is almost the same. Hereinafter, when the image DSP is described, it refers to an image displayed and output by the display panel 30 of the display device 1. In addition, at this time, the image can be viewed at a viewpoint in which the display device 1 is viewed from the front with a brightness higher than that of the other viewpoints. That is, when the liquid crystal panel 20 is in a non-operating state (OFF), the degree to which light along the third direction Z transmits through the liquid crystal panel 20 is equal to or higher than the degree to which light intersecting the third direction Z transmits 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 caused by the degree of light transmission when the liquid crystal panel 20 is in operation (ON). The center of the concentric circles in Fig. 7 corresponds to the normal line of the display device 1 along the third direction Z, and the concentric circles centered on the normal line indicate that the inclination angles with respect to the normal line are 20°, 40°, 60°, and 80°, respectively. The characteristic diagram shown here was obtained by connecting the regions of equal transmittance for each orientation.

[0052] As shown in Fig. 7, when the line of sight of the user with respect to the display device 1 is inclined toward one side (0°) of the first direction X, a relatively high light transmittance is obtained. Also, when the line of sight of the user with respect to the display device 1 is along the normal direction, that is, when the user looks at the display device 1 from the front, a relatively high light transmittance is obtained. In contrast, when the line of sight of the user with respect to the display device 1 is inclined 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 inclination angle of the line of sight toward the other side (180°) of the first direction X exceeds 30°, the transmittance becomes 3% or less in the example shown in Fig. 7, and the image becomes so dark that it is practically 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 who views 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 who views 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] FIG. 8 is a schematic diagram showing an example of the relationship between the display device 1, a user U1 who can view the image DSP regardless of whether the liquid crystal panel 20 is operating / non-operating (ON / OFF), and a user U2 who cannot view 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, that is, the fifth polarizing layer 42 side, is the user U1 side in FIG. 8. Therefore, the light LS1 of the image directed to the user U1 in association with the display output by the display device 1 is along the third direction Z. In the case of such a positional relationship between the display device 1 and the user U1, it can be said that the user U1 is at a viewpoint that views the display device 1 from the front. On the other hand, the user U2 is at a position that views the other side of the display device 1 obliquely from a direction inclined toward the other side of the first direction X with respect to the third direction Z. In other words, the light LS2 of the image directed to the user U2 in association with the display output by the display device 1 is inclined toward the other side of the first direction X (180° in FIG. 7). In the case of such a positional relationship between the display device 1 and the user U2, it can be said that the user U2 is at a viewpoint that views the display device 1 obliquely.

[0056] 8, a case where the display device 1 is provided in a four-wheeled vehicle in which the user U2 sits in the driver's seat and the user U1 sits in the passenger seat is assumed, but the case is not limited to this. For example, such a positional relationship may be provided when the display device 1 is provided 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 between the image DSP viewed by a user looking at the display device 1 from the front and a user looking at the display device 1 obliquely. The user looking at the display device 1 from the front is, for example, user U1 in FIG. 8. The user looking at the display device 1 obliquely is, for example, user U2 in FIG. 8. In the explanation 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 not operating (OFF) is defined as a first state. Also, 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 operating (ON) is defined as a second state.

[0058] As described above, when the liquid crystal panel 20 is not in operation (OFF), the degree to which light 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. Also, as described with reference to FIG. 7, even when the liquid crystal panel 20 is in operation (ON), a relatively high light transmittance is obtained when the user views the display device 1 from the front. Therefore, the image DSP shown in FIG. 9 can be viewed by a user viewing the display device 1 from the front, regardless of whether the operating state of the display device 1 is the first state or the second state. Note that the aspect of the image DSP shown in FIG. 9 is merely an example and is not limited thereto. 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°) of the first direction X, the light transmittance is significantly lower than that of the 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 of 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, a significant decrease in light transmittance as described with reference to FIG. 7 does not occur even on the other side (180°) of the first direction X. Therefore, when the operating state of the display device 1 is the first state, a user who views the display device 1 obliquely from the other side of the first direction X can view approximately the same image DSP as a user who views the display device 1 from the front.

[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 is a rectangle corresponding to the image DSP shown in FIG. 9. Of the four sides of the rectangle, two sides are along the first direction X, and the other two sides are along the second direction Y. The light control unit 10 of the embodiment makes the degree of light transmission of the ray inclined to one side of the longitudinal direction (first direction X) of the rectangle different from the degree of light transmission of the ray inclined to the other side of the longitudinal direction, based on the third direction Z. As a result, the light control unit 10 generates 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 mixture 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 in operation (ON) for each of the E mode and the O mode. The horizontal axis (polar angle) in Fig. 10 and Fig. 14 described later indicates the angle between the reference (0°) of the angle along the third direction Z and the ray of light inclined to the other side of the first direction X in the explanation with reference to Fig. 7 (the 180.0 side in Fig. 7). The vertical axis (transmittance) indicates the light transmittance of the ray corresponding to the polar angle indicated by the horizontal axis.

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

[0064] By utilizing the difference in optical characteristics between the E mode and the O mode as described with reference to Fig. 10, it is possible to realize viewing angle characteristics 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., the first liquid crystal panel 20A) provided as a liquid crystal panel for the E mode and one liquid crystal panel 20 (e.g., the second liquid crystal panel 20B) provided as a liquid crystal panel for the O mode, 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 the E mode only, the O mode only, and a combination of the E mode and the O mode. "E mode" shows only the E mode, that is, the dimming unit 10 has only an E mode liquid crystal panel. "O mode" shows only the O mode, that is, the dimming unit 10 has only an O mode liquid crystal panel. "E+O mode" shows a combination of the E mode and the O mode, that is, the dimming unit 10 has both the E mode and the 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, with the brightness of the image at the viewing angle at which the brightest image can be seen when the display device 1 is operating being taken as 1.0, and the state in which there is no light from the light source 60 (when the display device 1 is not operating) being taken as 0.0, and takes a value within the range of 0.0 to 1.0.

[0067] In FIG. 11 and FIG. 16 described later, normalized transmittances from 0.00 to 1.00 are shown at equal intervals along the vertical axis. In FIG. 12, the top end of the vertical axis is 1.0, and the value of the normalized transmittance is reduced to 1 / 10 for each scale mark downward. FIGS. 11 and 12 only differ in the way of expressing the vertical axis, and the relationship between the viewing angle and the normalized transmittance is the same. In the horizontal axis directions of FIGS. 11 and 12 and FIG. 16 described later, the line of sight when viewing the display device 1 from the front is used as a reference (a viewing angle of 0°), and the line of sight from an angle inclined to one side of the first direction X is shown as a viewing angle with a positive (+) value, and the line of sight from an angle inclined to the other side of the first direction X is shown as a viewing angle with a negative (-) value.

[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 on the plus (+) side of -20° and on the minus (-) side of -40°. Thus, with only the E mode, even a slight deviation from the viewing angle of -30° may leave the possibility of the image DSP being unintentionally visible even with squinting eyes.

[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 the suppression of visibility from the other side of the first direction X may be insufficient.

[0070] In contrast, when the light control unit 10 has both E-mode and O-mode liquid crystal panels as in the embodiment, the normalized transmittance falls significantly below 0.1 when the viewing angle is more negative than -20°. Moreover, as in the case of only E-mode, the normalized transmittance does not become 0.1 or more even when the viewing angle is more negative (-) than -40°. Thus, according to the embodiment, since the light control unit 10 has 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] 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 above-mentioned IPS type liquid crystal panel. 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 of image data from the outside. The following describes the configuration of pixels provided in the IPS type liquid crystal panel that can be used as the display panel 30 of the embodiment with reference to FIG. 13.

[0072] Fig. 13 is a plan view showing an example of a pixel layout in the display panel 30. Fig. 13 shows overlapping 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. 13. The pixel substrate 31 includes a plurality of scanning lines GCL and a plurality of signal lines S. The plurality of scanning lines GCL 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.

[0073] The pixel electrodes PE1 are aligned along the first direction X. The 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 pixel electrodes PE2 are aligned along the first direction X. The 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.

[0074] Next, the viewing angle control on the minus (-) side in the display device 1 operating in the second state will be described with reference to FIGS.

[0075] Fig. 14 is a diagram showing an example of the relationship between three viewing angles Ps1, Ps2, and Ps3 on the minus (-) side and the level of normalized transmittance. For the purpose of simplifying the explanation, Fig. 14 and Fig. 15 described later show the normalized transmittance (for example, "E+O mode") realized by the combination of two liquid crystal panels 20 described with reference to Fig. 11 as a broken line graph G1.

[0076] For example, assume that the normalized transmittance shown in the graph G1 of FIG. 14 is determined on the assumption that the image is not visible to the oblique view of a user corresponding to the viewing angle Ps1. Here, the "user corresponding to the viewing angle Psα" refers to a user who views the display device 1 from a position where the viewing angle to the display device 1 when viewing an image displayed and output by the display device 1 is the viewing angle Psα. α is a natural number. In this case, as described with reference to FIG. 9, the image of the display device 1 operating in the second state cannot be viewed by the user corresponding to the viewing angle Ps1. In addition, in this case, the image of the display device 1 operating in the second state cannot be viewed by the user corresponding to the viewing angle Ps3 on the negative (-) side of the viewing angle Ps1 in FIG. 14.

[0077] 14, the normalized transmittance is significantly higher at viewing angle Ps2, which is on the plus (+) side of viewing angle Ps1, than viewing angle Ps1. For this reason, a user at viewing angle Ps2 may be able to view an image.

[0078] There are various conditions related to determining the positional relationship between the display device 1 and a user who views the display device 1 obliquely. For this reason, if the normalized transmittance of the liquid crystal panel 20 is limited to that described with reference to Fig. 14, it may not be possible to say that the suppression of the user's visibility of the image corresponding to the viewing angle Ps2 in Fig. 14 is perfect.

[0079] Therefore, in the embodiment, the viewing angle range in which the normalized reduction rate can be reduced to a level sufficient to suppress the visibility of the image can be controlled by controlling the voltage applied to the liquid crystal LM. The voltage applied to the liquid crystal LM corresponds to the potential difference between the potential of the electrode FE1 and the potential of the electrode FE2. Hereinafter, unless otherwise specified, the term "reference voltage" refers to the voltage applied to the liquid crystal LM when the relationship between the normalized transmittance and the viewing angle corresponding to the graph G1 shown in FIG. 14 is established.

[0080] FIG. 15 is a diagram showing an example of the relationship between three viewing angles Ps1, Ps2, and Ps3 on the negative (-) side and the control of the normalized transmittance by controlling the voltage applied to the liquid crystal LM. Note that "positive voltage" in FIG. 15 indicates that the voltage applied to the liquid crystal LM is higher than the reference voltage. Graph G2 in FIG. 15 shows the normalized transmittance as an example of "positive voltage". Furthermore, "negative voltage" indicates that the voltage applied to the liquid crystal LM is lower than the reference voltage. Graph G3 shows the normalized transmittance as an example of "negative voltage".

[0081] As shown by "positive voltage" in Fig. 15, by making the voltage applied to the liquid crystal LM higher than the reference voltage, it is possible to make the image of the display device 1 operating in the second state invisible to a user corresponding to viewing angle Ps2. Also, as shown by "negative voltage" in Fig. 15, by making the voltage applied to the liquid crystal LM lower than the reference voltage, it is possible to make the image of the display device 1 operating in the second state invisible to a user corresponding to viewing angle Ps3, while being visible to a user corresponding to viewing angle Ps1.

[0082] The basic mechanism for controlling the normalized transmittance by controlling the voltage applied to the liquid crystal LM has been described above with reference to Fig. 15. Below, a more detailed relationship between the voltage applied to the liquid crystal LM and the normalized transmittance will be described with reference to Figs. 16 and 17.

[0083] FIG. 16 is a graph showing an example of normalized transmittance when the voltage applied to the liquid crystal LM is any one of 2 [V] to 2.7 [V] (in 0.1 V increments). FIG. 17 is a graph showing an example of the relationship between the voltage applied to the liquid crystal LM and the cut angle. The horizontal axis in FIG. 17 shows the voltage applied to the liquid crystal LM. The cut angle shown on the vertical axis in FIG. 17 is the tilt angle in the first direction X with respect to the display device 1, with the angle of the line of sight when viewing the display device 1 from the front being 0 degrees (°), and is the minimum tilt angle at which an image is viewed at a lower luminance than the luminance of the image when viewing the display device 1 from the front (or the image is substantially not viewable). For example, if the cut angle is 10°, a user viewing the display device 1 with a line of sight tilted in the first direction X by 10° or more with respect to the line of sight (0°) when viewing the display device 1 from the front will view the image at a lower luminance than the luminance of the image when viewing the display device 1 from the front, or will be in a state where the image is substantially not viewable. In addition, in the case of the display device 1 in which the viewing angle range where the normalized transmittance is substantially 0 is on the negative (-) side as shown in Fig. 16, the numerical values ​​of the cut angles shown in Fig. 17 are interpreted as indicating absolute values ​​of negative (-) numerical values. Conversely, in the case of the display device 1 in which the viewing angle range where the normalized transmittance is substantially 0 is on the positive (+) side, the numerical values ​​of the cut angles shown in Fig. 17 are interpreted as indicating positive (+) numerical values.

[0084] As shown in Fig. 16, the relationship between the polar angle and the normalized transmittance depends on the voltage applied to the liquid crystal LM. Specifically, as the voltage applied to the liquid crystal LM shifts from 2 [V] to 2.7 [V] in increments of 0.1 [V], the viewing angle range where the normalized transmittance is substantially 0, the polar angle where the normalized transmittance is the lowest, the polar angle where the normalized transmittance is the highest, the relationship between the normalized transmittance and the polar angle represented by the curved graph between the lowest normalized transmittance and the highest normalized transmittance, and the relationship between the normalized transmittance and the polar angle represented by the curved graph on the plus (+) side of the highest normalized transmittance all shift from the minus (-) side to the plus (+) side. Therefore, by setting the voltage applied to the liquid crystal LM in the display device 1 so that the polar angle assumed as the viewing angle of a user (unauthorized user) who should not be allowed to view an image is included in the viewing angle range where the normalized transmittance is substantially 0, it is possible to prevent the unauthorized user from viewing the image. In addition, by setting the polar angle assumed as the viewing angle of a user (authorized user) who may be able to view the image to the polar angle at which the normalized transmittance is highest or a polar angle close to that, it is possible for the authorized user to view the image.

[0085] Furthermore, using a similar concept to that explained with reference to Figure 16, as shown in Figure 17, the cut angle can be adjusted according to the voltage applied to the liquid crystal LM, so that by setting the cut angle to a polar angle between the polar angle assumed to be the viewing angle of an unauthorized user and the polar angle assumed to be the viewing angle of an authorized user, it is possible to realize viewing angle characteristics of the display device 1 that take into account both unauthorized users and authorized users.

[0086] In this way, the voltage applied to the liquid crystal LM, i.e., the potential difference between the electrodes FE2 and FE1, corresponds to the viewing angle range in which the normalized transmittance is substantially 0. In reality, as described above, the viewing angle range in which the normalized transmittance is substantially 0, the polar angle at which the normalized transmittance is the lowest, the polar angle at which the normalized transmittance is the highest, the relationship between the normalized transmittance and the polar angle represented by the curved graph between the lowest normalized transmittance and the highest normalized transmittance, and the relationship between the normalized transmittance and the polar angle represented by the curved graph on the plus (+) side from the highest normalized transmittance shift in response to a shift in the applied voltage to the liquid crystal LM, but the control of the applied voltage is performed primarily for the purpose of controlling the viewing angle range in which the normalized transmittance is substantially 0.

[0087] As described with reference to FIG. 7, FIG. 14, FIG. 15, FIG. 16, etc., the light control unit 10 uses the opposing direction (third direction Z) between the display panel 30 and the light source 60 as a reference to change the degree of light transmission inclined to one side (polar angle on the negative (-) side) of one direction (for example, the first direction X which is the longitudinal direction of the display panel 30) along two opposing sides of the four sides of the rectangular display panel 30, and the degree of light transmission inclined to the other side (polar angle on the positive (+) side). When the light control unit 10 is in operation, that is, in the second state, the angle of inclination at which the degree of light transmission is the lowest (the polar angle at which the normalized transmittance is the lowest) is included in either the one side or the other side. Here, the voltage applied to the liquid crystal LM, that is, the potential difference between the electrodes FE2 and FE1, is applied mainly for the purpose of controlling the viewing angle range in which the normalized transmittance is substantially 0, so that the potential difference can be said to correspond to the angle of inclination at which the degree of light transmission is lower when the liquid crystal panel 20 is in operation. 16 and 17, the larger the potential difference, the smaller the angle of the inclination with respect to the opposing direction (third direction Z) at which the degree of light transmission is the lowest. The viewing angle range in which the normalized transmittance is substantially zero can be said to be a set of viewing angles that are assumed to make it difficult or impossible to view the image output by the display panel 30 when the liquid crystal panel 20 is in operation (in the second state).

[0088] An assumed example of the positional relationship between the viewing angle of the display device 1 described above and the position of a user directing his / her gaze toward the display device 1 will be described with reference to FIG.

[0089] FIG. 18 is a schematic diagram showing an example of a position-angle relationship between the display device 1 and the seats SH1 and SH2 on which a user who will view the image of the display device 1 from an oblique angle is expected to sit. For example, in the position-angle relationship between the display device 1 and the seats SH1 and SH2 shown in FIG. 18, the viewing angle of the user sitting on the seat SH1 is expected to be a viewing angle θ1. Also, the viewing angle of the user sitting on the seat SH2 is expected to be a viewing angle θ2. Here, if the seats SH1 and SH2 and the display device 1 are installed in a vehicle such as a four-wheeled vehicle, and the seat SH1 is the driver's seat of the vehicle, it is desirable that the image of the display device 1 cannot be seen by the user sitting on the seat SH1 while driving the vehicle. Therefore, by setting the voltage applied to the liquid crystal LM to the display device 1 such that the polar angle corresponding to the viewing angle θ1 is included in the viewing angle range in which the normalized transmittance is substantially 0, it is possible to prevent the image of the display device 1 from being seen by the user sitting on the seat SH1 when the display device 1 is in the second state. Furthermore, by controlling the operation of the display device 1 so that it goes into a first state when the vehicle is stopped and goes into a second state when the vehicle is not stopped, it is possible to prevent the image on the display device 1 from being visible while the user sitting in the seat SH1 is driving the vehicle.

[0090] In addition, if there is no problem with the user sitting in seat SH2 being able to see the image, the cut angle can be set between viewing angle θ1 and viewing angle θ2 so that the user sitting in seat SH2 can see the image on display device 1.

[0091] The positional relationship between the display device 1 and the user who will be squinting at the image on the display device 1 is not limited to a predetermined one. Hereinafter, a configuration that allows the positional relationship between the display device 1 and the user who will be squinting at the image on the display device 1 to be variably set will be described with reference to FIG.

[0092] 19 is a schematic diagram showing an example of a configuration in which cameras Ca1 and Ca2 are used to identify the position-angle relationship between users U21 and U22 and the display device 1. The cameras Ca1 and Ca2 include an image sensor and a circuit that generates image data according to the output of the image sensor, and function as a so-called digital camera. The image sensor is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, but is not limited to this, and may be another configuration that functions similarly, such as a CCD (Charge Coupled Device) image sensor.

[0093] The camera Ca1 is disposed on the center line of the display device 1 in the first direction X, and the arrangement in the third direction Z is substantially the same as that of the display device 1. The camera Ca1 has a viewing angle facing the display output side of the display device 1. Here, the position of the user captured within the imaging range of the camera Ca1 can be associated with the viewing angle control of the display device 1. For example, the viewing angle of the user U22 is assumed to be a viewing angle θ3. The viewing angle of the user U21 is assumed to be a viewing angle θ4. In other words, by associating the imaging position of the user U22 in the imaging range of the camera Ca1 with the viewing angle θ3 and by associating the imaging position of the user U21 with the viewing angle θ4, the viewing angle control of the display device 1 based on the captured image of the camera Ca1 can be realized. For example, by setting the cut angle between the viewing angle θ3 and the viewing angle θ4 based on the imaging result of the camera Ca1, the user U22 cannot view the image, and the user U21 can view the image. Of course, the viewing angles are not limited to θ3 and θ4, and other viewing angles can be accommodated by appropriately associating the viewing angles with the user's position within the imaging range of the camera Ca1.

[0094] Furthermore, the arrangement of the camera capturing images for controlling the viewing angle of the display device 1 is not limited to the arrangement of the camera Ca1 shown in Fig. 19. For example, the camera Ca2 may be arranged at a position away from the display device 1 in the first direction X. Even in this case, by previously associating the user's position within the imaging range with the viewing angle, it is possible to realize viewing angle control of the display device 1 corresponding to the user's position captured within the imaging range. Of course, the viewing angle may be comprehensively controlled based on the imaging results of each of a plurality of cameras (for example, cameras Ca1 and Ca2).

[0095] The control of the voltage applied to the liquid crystal LM based on the captured image captured by the imaging unit such as the cameras Ca1 and Ca2, i.e., the potential difference between the electrodes FE2 and FE1, is performed by, for example, a control unit 70 shown in FIG. 19. The control unit 70 includes a circuit that realizes multiple functions. The circuit is, for example, a SoC (System on a Chip), but is not limited thereto, and may include multiple chips each performing different functions. The circuit performs image processing such as pattern matching and has a function of identifying an image of a user (e.g., users U21 and U22) included in the captured image by the imaging unit. The circuit also has a function of performing a calculation process to determine the positional and angular relationship between the user at the position and the display device 1 based on the positional and angular relationship between the user and the display device 1 specified by the calculation process. The circuit also has a function of determining the voltage applied to the liquid crystal LM based on the positional and angular relationship between the user and the display device 1 specified by the calculation process, and controlling the display device 1 so that the operation of the second state is performed with the determined applied voltage.

[0096] The camera Ca1 and the control unit 70 are connected by wiring within the display device 1. In the example shown in Fig. 19, the camera Ca2 and the control unit 70 are connected via wiring 71, but the captured image data may be transmitted and received via wireless communication.

[0097] In FIG. 19, for the purpose of clear illustration, the control unit 70 is provided in a form protruding from the rear side of the display device 1, but the form of the control unit 70 is not limited thereto. For example, a circuit functioning as the control unit 70 may be provided on a circuit board provided in the display device 1. Although not illustrated in any figures other than FIG. 19, a configuration (e.g., a circuit such as an SoC) having a function of controlling the voltage applied to the liquid crystal LM when the display device 1 operates in at least the second state among the functions performed by the control unit 70 is provided in the display device 1 in the same manner as the control unit 70 shown in FIG. 19. As described with reference to FIG. 18, when the positional relationship between the display device 1 and the user is assumed in advance, setting data indicating the voltage applied to the liquid crystal LM to realize the second state in which the cut angle corresponds to the assumption is held in the configuration in advance, and the configuration controls the voltage applied to the liquid crystal LM in accordance with the setting data.

[0098] As described above, according to the embodiment, the display device 1 includes a display panel 30 having a display area AA for outputting an image, a light source 60 for irradiating light from one side of the display panel 30, a liquid crystal panel 20 interposed between the display panel 30 and the light source 60 so as to be able to change the degree of light transmission between the display panel 30 and the light source 60, and a control unit (e.g., control unit 70) for controlling a potential difference between two electrodes FE1 and FE2 facing each other across liquid crystal in the liquid crystal panel 20. During operation, the liquid crystal panel 20 differentiates the degree of light transmission inclined to one side of the longitudinal direction (e.g., first direction X) of the rectangular display panel 30 from the degree of light transmission inclined to the other side of the longitudinal direction, based on the opposing direction (e.g., third direction Z) between the display panel 30 and the light source 60. The potential difference corresponds to an angle of inclination (e.g., a polar angle on the negative (-) side) at which the degree of light transmission is lower during operation of the liquid crystal panel 20.

[0099] This allows the potential difference between the two electrodes FE1, FE2 facing each other across the liquid crystal in the liquid crystal panel 20 to be set so that a user viewing the display device 1 from an inclination angle at which the degree of light transmission is lower when the liquid crystal panel 20 is in operation, i.e., a position angle at which it is undesirable to view an image on the display device 1 when the liquid crystal panel 20 is in operation, has difficulty or is unable to view the image. Therefore, by controlling the potential difference according to the position angle relationship between the display device 1 and the user, it is possible to make it difficult or impossible for the user to view an image when the liquid crystal panel 20 is in operation. In this way, according to the embodiment, the viewing angle range at which an image can be viewed can be set more flexibly.

[0100] Furthermore, the inclination angle at which the degree of light transmission is lowest when the liquid crystal panel 20 is in operation is included on either one side (e.g., the negative (-) side) or the other side (e.g., the positive (+) side), and the larger the potential difference between the two electrodes FE1, FE2 facing each other across the liquid crystal in the liquid crystal panel 20, the smaller the inclination angle at which the degree of light transmission is lowest. Therefore, by controlling the potential difference, it is possible to more flexibly control the viewing angle range at which it is difficult or impossible to view images when the liquid crystal panel 20 is in operation.

[0101] Furthermore, since the potential difference between the two electrodes FE1, FE2 facing each other across the liquid crystal in the liquid crystal panel 20 corresponds to a viewing angle that is expected to make it difficult or impossible to view an image when the liquid crystal panel 20 is in operation, within the viewing angle range in which an image can be viewed when the liquid crystal panel 20 is not in operation, it is possible to make it difficult or impossible for a user viewing the display device 1 to view an image from that viewing angle.

[0102] In addition, the display device 1 is provided with an imaging unit (e.g., cameras Ca1, Ca2) whose imaging range includes the viewing angle range of the display device 1 when the liquid crystal panel 20 is not operating, and a control unit (e.g., control unit 70) determines a viewing angle that is expected to make it difficult or impossible to view the image when the liquid crystal panel 20 is operating, based on the image captured by the imaging unit, thereby enabling more precise viewing angle control that corresponds to the positional angle relationship between the display device 1 and the user.

[0103] In addition, two liquid crystal panels 20 are provided, one of the two liquid crystal panels 20 (for example, the first liquid crystal panel 20A) is provided as an E-mode liquid crystal panel, and the other (for example, the second liquid crystal panel 20B) is provided as an O-mode liquid crystal panel, thereby realizing image display output utilizing both advantages of the E-mode liquid crystal panel and the O-mode liquid crystal panel. The advantage of the E-mode liquid crystal panel is a steep reduction in light transmittance with respect to the ray of light at a specific angle (for example, near a viewing angle of -30°). The advantage of the O-mode liquid crystal panel is a stable reduction in light transmittance in a wider range (for example, on the negative (-) side of a viewing angle of -30°). In addition, both the E-mode and the O-mode can transmit light that allows an image to be sufficiently viewed, except for a viewing angle range where the light transmittance is particularly reduced. In this way, according to the embodiment, a viewing angle range in which an image is viewable and a viewing angle range in which an image is not viewable can be simultaneously established, while a viewing angle range in which an image is not viewable can be more widely and more reliably secured.

[0104] 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 that 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 slow axis directions V02 and V08 of the retardation generating layers 51 and 52 may be changed so as to be linearly symmetrical with respect to the second direction Y.

[0105] In addition, in the embodiment, the light control unit 10 has two liquid crystal panels 20, but the number of liquid crystal panels 20 is not limited to two, and may be one, or three or more. When a configuration in which the number of liquid crystal panels 20 is different from that in the embodiment is adopted, the light transmission path LV can be established similarly to the embodiment by appropriately adding or changing optical members such as a polarizing layer and a phase difference generating layer according to the angle of polarization.

[0106] Furthermore, other advantageous effects brought about by the aspects described in this embodiment that are obvious 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]

[0107] 1 Display device 10. Dimming section 20 Liquid crystal panel 20A 1st LCD panel 20B Second LCD panel 23a, 24a Alignment film 30 Display Panel 60 light source 70 Control section Ca1,Ca2 camera FE1,FE2 electrode

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 liquid crystal panel interposed between the display panel and the light source so as to be capable of changing a degree of light transmission between the display panel and the light source; a control unit that controls a potential difference between two electrodes that face each other across the liquid crystal in the liquid crystal panel; the liquid crystal panel, during operation, differentiates a degree of light transmission inclined to one side in a longitudinal direction of the rectangular display panel from a degree of light transmission inclined to the other side in the longitudinal direction, based on a facing direction of the display panel and the light source; the potential difference corresponds to an angle of inclination at which light transmission is lower during operation of the liquid crystal panel; Display device.

2. the inclination angle at which the degree of light transmission is the lowest during operation of the liquid crystal panel is included in either the one side or the other side; The greater the potential difference, the smaller the angle of inclination at which light transmission is lowest. The display device according to claim 1 .

3. the potential difference corresponds to a viewing angle that is assumed to make it difficult or impossible to view the image when the liquid crystal panel is in operation, within a viewing angle range in which the image can be viewed when the liquid crystal panel is not in operation. The display device according to claim 1 .

4. an imaging unit having an imaging range including the viewing angle range, The control unit determines a viewing angle that is assumed to make it difficult or impossible to view the image when the liquid crystal panel is in operation, based on the image captured by the imaging unit. The display device according to claim 3 .

5. The liquid crystal panel is provided with two panels. One of the two liquid crystal panels is provided as an E-mode liquid crystal panel, and the other is provided as an O-mode liquid crystal panel. The display device according to claim 1 .

Images