Display device

Abstract

To provide a display device with high display quality.SOLUTION: In a first display pattern in which first input data corresponding to the first video is a first highest gradation and second input data corresponding to the second video is a second lowest gradation, the control unit sets the second lowest gradation as display data of the second video, and in a second display pattern in which the first input data is the first lowest gradation and the second input data is the second lowest gradation, the control unit sets a gradation higher than the second lowest gradation as the display data of the second video.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a display device including a display panel that displays a composite image, and aims to suppress the occurrence of crosstalk. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-38530 Summary of the Invention [Problem to be solved by the invention]

[0004] In the display device disclosed in Patent Document 1, when one of the two images constituting the composite image is displayed, crosstalk may occur in the other of the two images, which is not constant relative to the viewing angle of the other of the two images. In this respect, the display device disclosed in Patent Document 1 has room for improvement in display quality. [Means for solving the problem]

[0005] A display device according to one embodiment of the present disclosure includes a display unit that displays a first image that is visible in a first visible range and a second image that is visible in a second visible range in a superimposed manner, and a control unit that controls the display unit, wherein the control unit, in a first display pattern in which first input data corresponding to the first image is a first highest gradation and second input data corresponding to the second image is a second lowest gradation, sets the second lowest gradation as the display data of the second image, and in a second display pattern in which the first input data is the first lowest gradation and the second input data is the second lowest gradation, sets a gradation greater than the second lowest gradation as the display data of the second image. [Effects of the Invention]

[0006] According to one aspect of the present disclosure, a display device with high display quality can be realized. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a block diagram showing a configuration of a display device according to a first embodiment of the present disclosure. [Figure 2] 1 illustrates a schematic diagram of a dual view display. [Figure 3] FIG. 1 is a schematic plan view illustrating a dual-view structure. [Figure 4] 2 is a diagram for explaining various lights involved in dual view in an ideal operation example of the display device shown in FIG. 1. FIG. [Figure 5] 2 shows examples of a first image and a second image displayed in an ideal operation example of the display device shown in FIG. [Figure 6] 2 is a diagram for explaining various lights involved in dual view in an actual operation example of the display device shown in FIG. [Figure 7] 2 shows examples of a first video and a second video displayed in an example of actual operation of the display device shown in FIG. [Figure 8] 5 is a diagram illustrating various types of light involved in dual view in the exemplary operation of the display device shown in FIG. 1, different from FIG. 4. FIG. [Figure 9] FIG. 10 is a diagram illustrating an angle θ. [Figure 10] 2 is a graph showing an example of white luminance of the display device shown in FIG. [Figure 11] 10 is another graph showing an example of white luminance of the display device shown in FIG. [Figure 12] 2 is a graph showing an example of black luminance of the display device shown in FIG. [Figure 13] 2 is a graph showing an example of a crosstalk index value in the display device shown in FIG. [Figure 14] FIG. 2 is a block diagram showing an example of the configuration of a control unit. [Figure 15] 10 is a graph showing the range of display luminance of the second video that can be achieved when the first video is displayed, regardless of the display luminance of the first video. [Figure 16] 1 is a graph showing the luminance range MP versus the viewing angle. [Figure 17] FIG. 10 is a diagram illustrating correction of second input data based on a luminance range MP (30 to 60). [Figure 18] 10 is a graph showing an example of the relationship between luminance and gray scale in second input data after correction. [Figure 19] 10 shows an example of a table for converting second input data into display data for a second video. [Figure 20] FIG. 10 is a diagram illustrating a method for generating display data for the second video when the viewing angle is 45°, the second input data has 224 gray levels, and the display luminance of the first video is LumiRR240′. [Figure 21] This shows a comparison of the mechanisms by which the second image is generated. [Figure 22] This shows a comparison of the mechanisms by which the second image is generated. [Figure 23] FIG. 10 is a diagram for explaining various lights involved in dual view in an operation example of the display device according to the second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the present disclosure. For convenience of explanation, the same reference numerals are used to designate components having the same functions as those previously described, and the description thereof may not be repeated.

[0009] [Embodiment 1] FIG. 1 is a block diagram showing the configuration of a display device 1 according to a first embodiment of the present disclosure. The display device 1 includes a control unit 2 and a display unit 3. The display device 1 may be a mobile information terminal or a stationary display device. In this specification, backlight is abbreviated as "BL." In this specification, a case where the display device 1 is a liquid crystal display device is exemplified.

[0010] The control unit 2 comprehensively controls each component of the display device 1. The control unit 2 includes a panel control unit 21 and a BL control unit 22. The control unit 2 controls the display panel 31 and the BL 32.

[0011] Panel control unit 21 generates display data corresponding to any input data. The display data is data that indicates the spatial distribution of the light transmittance of the liquid crystal in display panel 31. Panel control unit 21 supplies the generated display data to panel drive unit 33.

[0012] The BL control unit 22 generates BL data corresponding to the input data. The BL data is data that indicates the spatial distribution of luminance in the BL 32. The BL control unit 22 supplies the generated BL data to the BL driving unit .

[0013] The display unit 3 displays an image in accordance with a command from the control unit 2. The display unit 3 is a liquid crystal display and includes a display panel 31, a BL 32, a panel drive unit 33, and a BL drive unit .

[0014] The display panel 31 has a display area in which a plurality of pixels PX are arranged. In this specification, a liquid crystal display panel is illustrated as an example of the display panel 31. The display panel 31 displays a predetermined image in accordance with instructions from the control unit 2.

[0015] In this specification, an XYZ Cartesian coordinate system is used. The X and Y directions correspond to the column and row directions of the display panel 31, respectively. The Z direction is the normal direction to the display surface of the display panel 31. In this specification, the user of the display device 1 is assumed to be located on the positive side of the Z direction. The positive side of the Z direction is also referred to as the viewer side. The negative side of the Z direction is also referred to as the substrate side. In this specification, the Z direction is also the thickness direction of the display device 1.

[0016] In this specification, the XY plane is a plane parallel to the display surface of the display panel 31. The display panel 31 has a plurality of pixels PX regularly arranged in both the X and Y directions.

[0017] The BL32 has a light source 321 for the display unit 3. The BL32 may have multiple light sources 321. By controlling the light emission of the multiple light sources 321, the spatial distribution of brightness in the BL32 can be controlled. The BL32 emits illumination light toward the display unit 3. In this specification, a case where the light source 321 is a white LED, in other words, a case where the illumination light is white light, is exemplified. LED is an abbreviation for Light Emitting Diode.

[0018] The panel driving unit 33 drives the display panel 31 in accordance with the display data acquired from the panel control unit 21. Specifically, the panel driving unit 33 changes the light transmittance at each position on the display panel 31 in accordance with the display data.

[0019] The BL driving unit 34 drives the BL 32 in accordance with the BL data acquired from the BL control unit 22. The BL driving unit 34 controls the lighting of the BL 32 in accordance with the BL data. The BL driving unit 34 controls the brightness of the plurality of light sources 321 in accordance with the BL data.

[0020] The control unit 2 (i) drives the display panel 31 through the panel drive unit 33, and (ii) drives the BL 32 through the BL drive unit , thereby causing the display panel 31 to display an image.

[0021] The display device 1 is a dual-view liquid crystal display device. The display unit 3 displays a first image visible in a first visible range AR1 and a second image visible in a second visible range AR2 in a superimposed manner. In this way, the display device 1 presents two separate images, the first image and the second image, depending on the user's viewing direction. The control unit 2 controls the display unit 3.

[0022] Fig. 2 shows a schematic diagram of dual view display on the display device 1. Fig. 2 shows a first user U1 and a second user U2.

[0023] 2, the side facing the negative X direction is referred to as the first side, and the side facing the positive X direction is referred to as the second side. The second side is the side opposite the first side in the X direction.

[0024] In this specification, it is assumed that a first user U1 is located within a first visible range AR1, and a second user U2 is located within a second visible range AR2.

[0025] 2, a first user U1 is located on a first side of the display surface, and a second user U2 is located on a second side of the display surface. A first image 190A is presented to the first user U1. A second image 190B is presented to the second user U2.

[0026] 3 is a schematic plan view illustrating a dual-view structure. The dual-view structure is a hardware configuration for realizing a dual-view display device. One pixel PX is composed of one red subpixel SUBPX_R, one green subpixel SUBPX_G, and one blue subpixel SUBPX_B. The red subpixel SUBPX_R has a red color filter, the green subpixel SUBPX_G has a green color filter, and the blue subpixel SUBPX_B has a blue color filter.

[0027] Of the white light emitted from BL32, the white light that enters the red subpixel SUBPX_R is converted to red light. Of the white light emitted from BL32, the white light that enters the green subpixel SUBPX_G is converted to green light. Of the white light emitted from BL32, the white light that enters the blue subpixel SUBPX_B is converted to blue light. In the display panel 31, an image is displayed on the display surface using the red light, green light, and blue light that are emitted from the pixels PX and proceed toward the viewing side.

[0028] The display panel 31 has a pixel group 313 including a first pixel group 313A and a second pixel group 313B, each having a plurality of pixels PX including liquid crystal. The first pixel group 313A is a group of pixels PX that contribute to displaying a first image. The second pixel group 313B is a group of pixels PX that contribute to displaying a second image.

[0029] The pixels PX located in odd-numbered columns belong to a first pixel group 313A, and the pixels PX located in even-numbered columns belong to a second pixel group 313B.

[0030] In the display panel 31, the first pixel groups 313A and the second pixel groups 313B are alternately positioned along the X direction. For example, when observed along the X direction, the first pixel groups 313A and the second pixel groups 313B may be alternately positioned in the display panel 31.

[0031] The display panel 31 has a plurality of separating members 316. The separating members 316 may contain any light-absorbing material. When viewed from the display surface, the separating members 316 overlap with a portion of the first pixel group 313A and with a portion of the second pixel group 313B. The separating members 316 are located closer to the viewer than the first pixel group 313A and the second pixel group 313B.

[0032] In this specification, the illumination light emitted from BL32 and wavelength-converted by the first pixel group 313A is referred to as the first light, and the illumination light emitted from BL32 and wavelength-converted by the second pixel group 313B is referred to as the second light. The separating member 316 prevents a portion of the first light from traveling toward the display surface of the display panel 31. The separating member 316 also prevents a portion of the second light from traveling toward the display surface.

[0033] Fig. 4 is a diagram illustrating various types of light involved in dual view in an ideal operation example of the display device 1. The display panel 31 is located closer to the viewer than the BL 32. Fig. 4 illustrates the components of the display panel 31, including the first pixel group 313A, the second pixel group 313B, the separation member 316, and the display surface 319.

[0034] The BL driving unit 34 drives the BL 32 in accordance with a command from the BL control unit 22. Illumination light 80 is emitted from the BL 32 toward the first pixel group 313A and the second pixel group 313B. In the example shown in Fig. 4, the BL 32 does not have any particular light directivity.

[0035] Panel driving unit 33 drives display panel 31 in accordance with instructions from panel control unit 21. Panel driving unit 33 drives first pixel group 313A and second pixel group 313B in accordance with instructions from panel control unit 21. Panel control unit 21 drives first pixel group 313A and second pixel group 313B under the control of panel driving unit 33 so as to cause display panel 31 to display a first video image and a second video image.

[0036] In an ideal operating example, the light absorption rate of the separation members 316 is 100%. Adjacent two of the separation members 316 form a gap HL that allows a portion of the first light and a portion of the second light to pass through. The gap HL is positioned so as to expose a portion of each of the first pixel group 313A and the second pixel group 313B when viewed from the display surface.

[0037] A portion of the first light having directionality toward the first side passes through the gap HL and heads toward the display surface 319. Light 81A is an example of first light having directionality toward the first visible range AR1 that passes through the gap HL and heads toward the display surface 319. Light 81A has directionality toward the first side, for example. Light 81A contributes to the formation of a first image on the display surface 319.

[0038] A portion of the second light having directionality toward the second side passes through the gap HL and proceeds toward the display surface 319. Light 81B is an example of the second light having directionality toward the second visible range AR2 that passes through the gap HL and proceeds toward the display surface 319. Light 81B has directionality toward the second side, for example. Light 81B contributes to the formation of a second image on the display surface 319.

[0039] Fig. 5 shows examples of the first and second images displayed in an ideal operation example of the display device 1. Fig. 5 corresponds to the example of Fig. 4. The first image 190A is an image showing a black background and a white circle located in the center. The second image 190B is an image showing a black and white checkered pattern.

[0040] In an ideal example, no crosstalk occurs between first image 190A and second image 190B. In this specification, crosstalk refers to a phenomenon in which one displayed image is mixed with another displayed image in a multi-view display such as a dual-view display.

[0041] 6 is a diagram illustrating various types of light involved in dual viewing in an actual operation example of the display device 1. In an actual operation example, unlike the ideal operation example, the first light, which has directivity toward the second side, is not completely blocked by the separating member 316. For example, in the actual operation example, a portion of the first light passes through the gap HL toward the display surface 319. Light 82A is an example of the first light, which has directivity toward the second visible range AR2 and passes through the gap HL toward the display surface 319.

[0042] In an actual operation example, the light of the second light that has directionality toward the first side is not completely blocked by separation member 316. For example, in an actual operation example, a portion of the second light passes through gap HL toward display surface 319. Light 82B is an example of the second light that passes through gap HL toward display surface 319 and has directionality toward first visible range AR1.

[0043] The actual light absorption rate of separating member 316 is lower than 100%. In an actual operating example, a portion of the first light passes through a portion of separating member 316 that overlaps with first pixel group 313A and second pixel group 313B and proceeds toward display surface 319. In an actual operating example, a portion of the second light passes through this portion and proceeds toward display surface 319. Light 83A is an example of the first light that passes through this portion and proceeds toward display surface 319, and has directionality toward second visible range AR2. Light 83B is an example of the second light that passes through this portion and proceeds toward display surface 319, and has directionality toward first visible range AR1.

[0044] FIG. 7 shows an example of the first and second images displayed in an actual operation example of the display device 1. In the actual operation example, a portion of the first light finds its way into the second viewable range AR2. As a result, the second image 191B is an image in which the first image 190A is mixed into the second image 190B. The mixing of the first image 190A into the second image 190B is caused by light 82A and light 83A. Light 82A and light 83A are the first light that is undesirable in dual-view display.

[0045] In an actual operation example, a portion of the second light finds its way into first visible range AR1. As a result, first image 191A is an image in which second image 190B is mixed into first image 190A. The mixing of second image 190B into first image 190A is caused by light 82B and light 83B. Light 82B and light 83B are second light that is undesirable in dual-view display.

[0046] FIG. 8 is a diagram illustrating various types of light involved in dual viewing in an example of the operation of the display device 1, different from FIG. 4. In the example shown in FIG. 8, the direction in which the light emission intensity of the light source 321 is greatest is the direction passing through two adjacent gaps HL among the multiple separating members 316. Hereinafter, a configuration in which the light emission intensity of the light source 321 is greatest is the direction passing through two adjacent gaps HL among the multiple separating members 316 is also referred to as configuration α. ​​Examples of light sources 321 that can realize configuration α include those having a prism-shaped light guide, those having a viewing angle control film, and those having a louver. The multiple light sources 321 can be turned on separately on the first side and the second side.

[0047] FIG. 9 is a diagram illustrating angle θ. θ represents the tilt angle in the X direction relative to the Y axis. θ is a parameter corresponding to the line of sight of a user when the user views the display surface. In this specification, when the optical axis of interest is parallel to the Y axis, θ=0°. When the optical axis of interest is optical axis 1310, θ=0°.

[0048] The following can be said about FIG. 9. When the orientation of the optical axis of interest coincides with the negative X direction, θ=−90°. When the optical axis of interest is optical axis 1320, θ<0°. The first user U1 is located on the side where θ is negative. The side where θ is negative is written as “θ=−side.” “θ=−side” corresponds to the first side.

[0049] The following can be said about Figure 9. When the orientation of the optical axis of interest coincides with the positive direction of the X direction, θ = 90°. When the optical axis of interest is optical axis 1330, θ > 0°. The second user U2 is located on the side where θ is positive. The side where θ is positive is written as "θ = + side." "θ = + side" corresponds to the second side.

[0050] FIG. 10 is a graph showing an example of white luminance of the display device 1. White luminance is the luminance of the display diagram of a white display image. FIG. 11 is another graph showing an example of white luminance of the display device 1. FIG. 12 is a graph showing an example of black luminance of the display device 1. Black luminance is the luminance of the display diagram of a black display image. FIG. 13 is a graph showing an example of crosstalk index values ​​in the display device 1.

[0051] For example, if the first side is set to white display and the second side is set to black display, crosstalk is defined as an index that indicates how much the brightness of the black display on the second side is increased due to the influence of light leakage from the first side. Here, crosstalk is sometimes abbreviated as XT.

[0052] Crosstalk is defined as follows:

[0053] First side: (AKBW-AKBK) / AKBK Second side: (AWBK-AKBK) / AKBK W means white display and K means black display. AWBK means that the first side is white display and the second side is black display. AKBW means that the first side is black display and the second side is white display. AKBK means that the first side is black display and the second side is black display. AWBW means that the first side is white display and the second side is white display.

[0054] -A, -B, -AB, and -S each indicate a case where the configuration α is applied. -A indicates that the light source 321 corresponding to the first side (which irradiates light onto the first pixel group 313A) is turned on. -B indicates that the light source 321 corresponding to the second side (which irradiates light onto the second pixel group 313B) is turned on. -AB indicates a case where both the light source 321 corresponding to the first side and the light source 321 corresponding to the second side are always turned on. -S indicates a case where the light source 321 corresponding to the first side and the light source 321 corresponding to the second side are switched on at high speed. -N indicates a case where the configuration α is not applied.

[0055] In the following discussion of crosstalk, we use the combinations AWBK, AKBW, ​​AKBK, and AWBW with -A, -B, -AB, -S, and -N. To avoid confusion with mathematical symbols, the combinations are written in double quotes. For example, AWBK and -A is written as "AWBK-A."

[0056] Regarding -S, by switching on the light, the following is assumed to be true:

[0057] “AWBK-S”=(“AWBK-A”+“AKBK-B”) / 2 “AKBW-S”=(“AKBW-B”+“AKBK-A”) / 2 “AKBK-S”=(“AKBK-A”+“AKBK-B”) / 2 “AWBW-S”=(“AWBW-A”+“AWBW-B”) / 2 According to FIG. 12, it can be confirmed that the application of the configuration α reduces the black luminance and reduces crosstalk.

[0058] The crosstalk in the display device 1 to which -S is applied is as follows.

[0059] 1st side: (“AKBW-S”-“AKBK-S”) / “AKBK-S” Second side: (“AWBK-S”-“AKBK-S”) / “AKBK-S” By applying -S, the floating of the black side in "AKBW-S" and "AWBK-S" is reduced, and crosstalk reduction can be confirmed.

[0060] By applying the configuration α, crosstalk at a specific viewing angle can be suppressed, but there is a risk that crosstalk at other viewing angles may not be suppressed. The more directional the light source 321 is, the more noticeable the difference in luminance of the display device 1 depending on the viewing angle becomes. Even when the configuration α is applied to the display device 1, there is still room for improvement in display quality.

[0061] 1 and 2, the display device 1 includes a control unit 2 and a display unit 3. The display unit 3 displays a first image visible in a first visible range AR1 and a second image visible in a second visible range AR2 in a superimposed manner. The control unit 2 controls the display unit 3.

[0062] In a first display pattern in which the first input data corresponding to the first image is the first highest gradation and the second input data corresponding to the second image is the second lowest gradation, the control unit 2 sets the second image display data to the second lowest gradation.In a second display pattern in which the first input data is the first lowest gradation and the second input data is the second lowest gradation, the control unit 2 sets the second image display data to a gradation greater than the second lowest gradation.

[0063] In the first display pattern, the luminance of the second visible range AR2 may be constant across a plurality of viewing angles.In the second display pattern, the luminance of the second visible range AR2 may be constant across a plurality of viewing angles.This makes it possible to reduce differences in the luminance of the second image on the display device 1 depending on the viewing angle.

[0064] When the first input data is the first highest gradation and the second input data is the second highest gradation, the control unit 2 may set a gradation smaller than the second highest gradation as the display data for the second image.When the first input data is the first lowest gradation and the second input data is the second highest gradation, the control unit 2 may set the second highest gradation as the display data for the second image.

[0065] 14 is a block diagram showing an example of the configuration of the control unit 2. The panel control unit 21 of the control unit 2 may include a brightness range calculation unit 211, a correction unit 212, and a conversion unit 213.

[0066] 15 is a graph showing the range of display luminance of the second image that can be achieved when the first image is displayed, regardless of the display luminance of the first image. Panel control unit 21 of control unit 2 processes first input data input to control unit 2 to generate display data of the first image, and supplies the display data of the first image to panel drive unit 33 of display unit 3. Panel control unit 21 of control unit 2 processes second input data input to control unit 2 to generate display data of the second image, and supplies the display data of the second image to panel drive unit 33 of display unit 3.

[0067] The display brightness of the first video corresponds to the grayscale of the first input data. The grayscale of the first input data ranges from 0, which corresponds to the minimum brightness, to 255, which corresponds to the maximum brightness. In Figure 15, β is an integer between 0 and 255, and the brightness corresponding to the β grayscale of the first input data is expressed as Rβ.

[0068] Although the display brightness of the second video is affected by crosstalk, which will be described later, it basically corresponds to the grayscale of the second input data. The grayscale of the second input data ranges from 0, which corresponds to the minimum brightness, to 255, which corresponds to the maximum brightness. In FIG. 15, γ is an integer between 0 and 255, and the γ grayscale of the second input data is expressed as LumiL[any of A to E]γ. [any of A to E] will be explained below.

[0069] According to FIG. 15, it was found that when the first video is displayed, the range of achievable display luminance of the second video changes depending on the display luminance of the first video.

[0070] For 0 gradation of the first input data, the range of achievable display luminance of the second video image corresponding to the display luminance of the first video image when the first video image is displayed is from LumiLA0 corresponding to the minimum luminance to LumiLA255 corresponding to the maximum luminance. For 64 gradation of the first input data, the range of achievable display luminance of the second video image corresponding to the display luminance of the first video image when the first video image is displayed is from LumiLB0 corresponding to the minimum luminance to LumiLB255 corresponding to the maximum luminance. For 128 gradation of the first input data, the range of achievable display luminance of the second video image corresponding to the display luminance of the first video image when the first video image is displayed is from LumiLC0 corresponding to the minimum luminance to LumiLC255 corresponding to the maximum luminance.

[0071] For 192 gradations of the first input data, the range of achievable display luminance of the second video image according to the display luminance of the first video image when the first video image is displayed is from LumiLD0 corresponding to the minimum luminance to LumiLD255 corresponding to the maximum luminance. For 255 gradations of the first input data, the range of achievable display luminance of the second video image according to the display luminance of the first video image when the first video image is displayed is from LumiLE0 corresponding to the minimum luminance to LumiLE255 corresponding to the maximum luminance.

[0072] Consider a case where the control unit 2 sets 0 gradation (second lowest gradation) of the second input data as the display data for the second video in both the first display pattern and the second display pattern. The first display pattern is a pattern in which the first input data is 255 gradation (first highest gradation) and the second input data is 0 gradation. The display luminance of the second video in the first display pattern is LumiLE0. The second display pattern is a pattern in which the first input data is 0 gradation (first lowest gradation) and the second input data is 0 gradation. The display luminance of the second video in the second display pattern is LumiLA0. A phenomenon occurs in which the display luminance of the second video differs between the first display pattern and the second display pattern, even though the second input data is both 0 gradation. Crosstalk includes a first component corresponding to this phenomenon. Because the difference between LumiLE0 and LumiLA0 corresponds to the first component, the following relationship holds for the first component:

[0073] (AWBK-AKBK) / AKBK=(LumiLE0-LumiLA0) / LumiLA0 Consider a case where the control unit 2 sets 255 gradation (second highest gradation) of the second input data as the display data for the second video in both the third display pattern and the fourth display pattern. The third display pattern is a pattern in which the first input data is 255 gradation and the second input data is 255 gradation. The display luminance of the second video in the third display pattern is LumiLE255. The fourth display pattern is a pattern in which the first input data is 0 gradation and the second input data is 255 gradation. The display luminance of the second video in the fourth display pattern is LumiLA255. Even though the second input data is both 255 gradation, a phenomenon occurs in which the display luminance of the second video differs between the third display pattern and the fourth display pattern. Crosstalk includes a second component corresponding to this phenomenon.

[0074] If the display luminance of the second video is limited to LumiLE0 or higher, which has the highest luminance among LumiLA0 to LumiLE0, the second video can be displayed without being affected by the first component. If the display luminance of the second video is limited to LumiLA255 or lower, which has the lowest luminance among LumiLA255 to LumiLE255, the second video can be displayed without being affected by the second component.

[0075] In other words, when the primary video is displayed, the range of display luminance of the secondary video that can be achieved regardless of the display luminance of the primary video is a luminance range MP from LumiLE0 to LumiLA255. The luminance range calculation unit 211 determines the luminance range MP.

[0076] 16 is a graph showing the luminance range MP versus viewing angle. The viewing angle when the first video is viewed is θ (negative value), and the viewing angle when the second video is viewed is θ (positive value).

[0077] Fig. 16 shows that the luminance range MP varies depending on the viewing angle. Fig. 16 shows the luminance range MP for five viewing angles within the viewing angle range of 30° to 60°: 30°, 37.5°, 45°, 52.5°, and 60°. In Fig. 16, the luminance range MP at a viewing angle of δ° is denoted as MP(δ).

[0078] 16, the minimum value of the luminance range MP is LumiL0, which is smallest at MP(60) and largest at MP(30). The crosstalk includes a third component corresponding to the difference between LumiL0 and the minimum value of MP(60).

[0079] 16, the maximum value of the luminance range MP is LumiL255, which is greatest at MP(45) and smallest at MP(60). The crosstalk includes a fourth component corresponding to the difference between LumiL255 and the maximum value of MP(45).

[0080] If the display luminance of the second video is limited to LumiL0 or higher, which has the largest minimum value in the luminance range MP within the viewing angle range of 30° to 60°, the second video can be displayed without being affected by the third component. If the display luminance of the second video is limited to LumiL255 or lower, which has the smallest maximum value in the luminance range MP within the viewing angle range of 30° to 60°, the second video can be displayed without being affected by the fourth component.

[0081] In other words, when the first video is displayed, the range of display luminance of the second video that can be realized regardless of the display luminance of the first video at any viewing angle within the range of 30° to 60° is the luminance range MP(30 to 60) from LumiL0 to LumiL255. The luminance range calculation unit 211 calculates the luminance range MP(30 to 60).

[0082] 17 is a diagram illustrating correction of the second input data based on the luminance range MP (30 to 60). The correction unit 212 corrects the second input data based on the luminance range MP (30 to 60) in the manner shown in FIG. 17 and its explanation.

[0083] In FIG. 17, the luminance corresponding to the β gradation of the second input data before correction based on the luminance range MP (30 to 60) is represented as Lβ. In the second input data after correction based on the luminance range MP (30 to 60), the minimum luminance is LumiL0, which is greater than L0, and the maximum luminance is LumiL255, which is less than L255. The range that can exist as a combination of viewing angle and luminance of the second input data is compressed from region LG to region LE after correction. In the second input data after correction, gradations 0 to 255 may be newly assigned within the luminance range from LumiL0 to LumiL255.

[0084] 18 is a graph showing an example of the relationship between brightness and gradation in the second input data after correction. When correcting the second input data, the correction unit 212 sets the brightness corresponding to gradation 0 of the second input data to LumiL0, sets the brightness corresponding to gradation 255 of the second input data to LumiL255, and applies gamma 2.2 or the like to expand the second input data. The brightness corresponding to the intermediate tones of the second input data is preferably determined based on gamma 2.2 or the like, but may also be determined based on a gamma curve other than gamma 2.2 or the like.

[0085] Next, conversion unit 213 creates a table for converting the second input data into display data for the second image. Conversion unit 213 determines how the display luminance of the second image changes in response to changes in the gradation of the second input data in accordance with the display luminance of the first image at each of a plurality of points within a viewing angle range of 30° to 60°. An example of this table is shown in FIG. 19.

[0086] A case where the viewing angle is 45°, the second input data has 224 gradations, and the display luminance of the first video is LumiRR240' will be described with reference to FIG. 20. The conversion unit 213 determines the target luminance when actually displayed. The conversion unit 213 determines which luminance in a luminance table interpolated using a gamma curve or the like corresponds to the target gradation value of the input video. In the example shown in FIG. 20, the luminance corresponding to 224 gradations of the second input data after correction is luminance A.

[0087] Next, conversion unit 213 uses the target table to determine how many gradations should be displayed to achieve display luminance A for the second video when the viewing angle is 45° and the display luminance of the first video is LumiRR240'. In this example, luminance A is achieved when 220 gradations are displayed.

[0088] In the case of a striped structure, since pixels PX belonging to the first pixel group 313A are located on either side of the second pixel group 313B, the display luminance of the first image may be calculated as the average value of the luminance values ​​corresponding to the two adjacent pixels PX, or may be calculated using values ​​in the X or Y direction. Even in the case of a non-striped structure, the value of a pixel PX belonging to the first pixel group 313A that is close to a pixel PX belonging to the second pixel group 313B may be used. The grayscale value is converted to a luminance value using a post-compression gamma curve corresponding to the first input data.

[0089] To convert the first input data into a brightness value, the gamma curve after compression may not be used, but data obtained by measuring the brightness value of the first image when displayed as is may be used, or gamma 2.2 or the like may be used to convert from a gradation value to a brightness value.

[0090] 15 to 20 and their explanations. This allows the display luminance of the second video to be kept within a luminance range that is feasible regardless of the display luminance of the first video, at any viewing angle within the range of 30° to 60°. Therefore, crosstalk caused by the display of the first video and / or the viewing angle of the second video can be reduced, thereby realizing a display device 1 with high display quality.

[0091] When the second input data is the second highest gradation and the first input data is the first lowest gradation, the control unit 2 may set the first lowest gradation as the display data for the first image. The control unit 2 may set a gradation greater than the first lowest gradation as the display data for the first image in the second display pattern. This provides the same effect for the first image as for the second image.

[0092] When the second input data is the second highest gradation and the first input data is the first highest gradation, the control unit 2 may set a gradation smaller than the first highest gradation as the display data for the first image. When the second input data is the second lowest gradation and the first input data is the first highest gradation, the control unit 2 may set the first highest gradation as the display data for the first image. This provides the same effect for the first image as for the second image.

[0093] By doing this, the display brightness of the second video is made uniform and crosstalk is reduced. By making the same correction for the first video, it is effective for both displays.

[0094] When the control unit 2 operates in the above manner, the display device 1 may have the following configuration due to at least one of the corrections to the first input data and the corrections to the second input data: The control unit 2 differentiates the luminance characteristics for the gradations in the first input data from the luminance characteristics for the gradations in the second input data.

[0095] The display unit 3 includes a pixel group 313 having a plurality of pixels PX including liquid crystal that display a first image and a second image, a light source 321 that irradiates light onto the pixel group 313 from the rear surface of the pixel group 313, and a plurality of separating members 316 that separate the first image and the second image. The direction in which the light emission intensity of the light source 321 is greatest may be a direction that passes through two adjacent gaps HL of the plurality of separating members 316. This suggests that the display device 1 may have a configuration α.

[0096] 15, 16, 19, etc., the table in Fig. 19 may be a table for each gradation, or may be a table interpolated based on a table with a pitch of several gradations. Also, the pitch in angle (viewing angle) may be finer, or may be interpolated in increments of about 5°.

[0097] The display device 1 can be applied to a privacy mode in an in-vehicle dual-view display. In an in-vehicle dual-view display, a mode is required in which the image being viewed by the passenger in the passenger seat is not visible from the driver's seat, and only the passenger seat can see. When the present disclosure is applied to the privacy mode, the driver's seat side is displayed in black, as shown in FIG. 21, and the driver's seat side is displayed in white, as shown in FIG. 22. Each of FIGS. 21 and 22 shows a comparison of the mechanisms for generating the second image.

[0098] 21 and 22, "without correction" indicates a case where panel control unit 21 of control unit 2 does not operate in the manner shown in Figures 15 to 20 and their descriptions. In each of Figures 21 and 22, "with correction" indicates a case where panel control unit 21 of control unit 2 operates in the manner shown in Figures 15 to 20 and their descriptions.

[0099] [Embodiment 2] 23 is a diagram for explaining various types of light involved in dual view in an operation example of the display device 1 according to the second embodiment of the present disclosure. The technology of the present disclosure is also applicable to the time-division dual view shown in FIG.

[0100] In term A, a first image is displayed on the first pixel group 313A. In term A, only those of the plurality of light sources 321 necessary for displaying the first image are turned on. In term B, a second image is displayed on the second pixel group 313B. In term B, only those of the plurality of light sources 321 necessary for displaying the second image are turned on. In the display device 1 according to the second embodiment of the present disclosure, terms A and B are switched at high speed, and terms A and B are continuously repeated.

[0101] In the display device 1 according to the second embodiment of the present disclosure, display is performed on every other column of the pixels PX, but if the resolution is sufficiently high, there is no serious problem of degradation in display quality in the display device 1. In term A, the second video is displayed in black, and the corresponding light source 321 is not lit, so light leakage to the second side is significantly reduced.

[0102] In a time-sequential dual view display, crosstalk is reduced, but there is a risk of adverse effects due to the response of the liquid crystal. Furthermore, if there is a temperature gradient within the display surface 319, the response time of the liquid crystal may differ depending on the location within the display surface 319, and the actual brightness achieved when displaying white may differ. In a time-sequential dual view display, it is necessary to reduce crosstalk due to the response of the liquid crystal.

[0103] In the display device 1 according to the second embodiment of the present disclosure, by performing the same control as the display device 1 according to the first embodiment of the present disclosure, it is also possible to reduce crosstalk caused by the responsiveness of the liquid crystal.

[0104] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of symbols]

[0105] 1 Display device 2. Control section 3 Display section 313 pixel group 316 Separation member 321 Light source HL gap

Claims

1. a display unit that displays a first image visible in a first visible range and a second image visible in a second visible range in a superimposed manner, and a control unit that controls the display unit; The control unit, in a first display pattern in which first input data corresponding to the first image is a first highest gradation and second input data corresponding to the second image is a second lowest gradation, sets the second lowest gradation as the display data of the second image, and, in a second display pattern in which the first input data is the first lowest gradation and the second input data is the second lowest gradation, sets a gradation greater than the second lowest gradation as the display data of the second image.

2. The display device according to claim 1 , wherein in the first display pattern, the luminance of the second visible range is constant across a plurality of viewing angles.

3. The display device according to claim 1 , wherein in the second display pattern, the luminance of the second visible range is constant across a plurality of viewing angles.

4. 3. The display device of claim 1, wherein the control unit sets a gradation smaller than the second highest gradation as the display data for the second image when the first input data is the first highest gradation and the second input data is the second highest gradation, and sets the second highest gradation as the display data for the second image when the first input data is the first lowest gradation and the second input data is the second highest gradation.

5. 3. The display device of claim 1, wherein when the second input data is the second highest gradation and the first input data is the first lowest gradation, the control unit sets the first lowest gradation as the display data of the first image, and in the second display pattern, sets a gradation greater than the first lowest gradation as the display data of the first image.

6. 6. The display device of claim 5, wherein the control unit sets a gradation smaller than the first highest gradation as the display data for the first image when the second input data is the second highest gradation and the first input data is the first highest gradation, and sets the first highest gradation as the display data for the first image when the second input data is the second lowest gradation and the first input data is the first highest gradation.

7. The display device according to claim 1 , wherein the control unit differentiates a characteristic of luminance relative to a gradation in the first input data from a characteristic of luminance relative to a gradation in the second input data.

8. The display unit a pixel group including a plurality of pixels including liquid crystal, which displays the first image and the second image; a light source that irradiates light onto the pixel group from behind the pixel group; a plurality of separating members for separating the first image and the second image; 3. The display device according to claim 1, wherein the direction in which the light emission intensity of the light source is greatest is a direction passing through two adjacent gaps among the plurality of separating members.

Images