Display device and control method of display device

Abstract

To provide a display device capable of properly inhibiting occurrence of saturation of a liquid crystal transmissivity according to external environment information or characteristic information on an input image.SOLUTION: A display device includes a luminance value determination unit that determines a luminance value of each of backlight areas on the basis of an input image, an image processing unit that, when a division display area of a liquid crystal panel corresponding to each of the backlight areas includes a first area having a pixel of the input image whose luminance value is equal to or larger than an intermediate luminance, generates an after-processing image in which the luminance value of the first area is reduced based on external environment information or characteristic information on the input image, a liquid crystal transmissivity determination unit that determines a liquid crystal transmissivity in each division display area on the basis of the after-processing image and the luminance value of each of the backlight areas, and a display control unit that controls display of the input image on the basis of the luminance values of the respective backlight areas and the liquid crystal transmissivity determined by the liquid crystal transmissivity determination unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a display device and a method for controlling the display device. [Background technology]

[0002] Patent Document 1 discloses a display device that performs display processing using a local dimming function. In Patent Document 1, when the liquid crystal transmittance of the liquid crystal panel in a low-luminance region where the luminance is reduced and displayed is equal to or greater than a predetermined value, the luminance of the input image is reduced. With this configuration, Patent Document 1 can prevent the saturation of the liquid crystal transmittance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 239918 Summary of the Invention [Problem to be solved by the invention]

[0004] The display device disclosed in Patent Document 1 does not take into consideration the viewing environment of the viewer who views the display device and does not have a configuration for suppressing the occurrence of saturation of the liquid crystal transmittance.

[0005] An object of the present disclosure is to provide a display device and a method for controlling the display device that can appropriately suppress the occurrence of saturation of liquid crystal transmittance in accordance with environmental information external to the display device or characteristic information of an input image. [Means for solving the problem]

[0006] A display device according to one embodiment of the present disclosure includes a brightness value determination unit that determines, based on an input image, a brightness value for each backlight area obtained by dividing a backlight illumination region into multiple areas; an image processing unit that generates a processed image in which the brightness value of the first area is reduced based on external environmental information or characteristic information of the input image when a first area including pixels of the input image having a brightness value of medium brightness or higher is present in a divided display area of ​​a liquid crystal panel corresponding to each of the backlight areas; a liquid crystal transmittance determination unit that determines the liquid crystal transmittance in each of the divided display areas based on the processed image and the brightness value of each of the backlight areas determined by the brightness value determination unit; and a display control unit that controls the display of the input image based on the brightness value of the backlight area determined by the brightness value determination unit and the liquid crystal transmittance determined by the liquid crystal transmittance determination unit.

[0007] A control method for a display device according to one embodiment of the present disclosure is a control method for a display device having a liquid crystal panel and a backlight, and includes: a brightness value determination step of determining, based on an input image, a brightness value for each of backlight areas obtained by dividing a lighting area of ​​the backlight into a plurality of areas; an image generation step of generating, if a first area including pixels having a brightness value of the input image that is medium brightness or higher is present in a divided display area of ​​the liquid crystal panel corresponding to each of the backlight areas, a processed image in which the brightness value of the first area is reduced based on external environmental information or characteristic information of the input image; a liquid crystal transmittance determination step of determining the liquid crystal transmittance in each of the divided display areas based on the processed image and the brightness value of each of the backlight areas determined in the brightness value determination step; and a display control step of controlling the display of the input image based on the brightness value of the backlight area determined in the brightness value determination step and the liquid crystal transmittance determined in the liquid crystal transmittance determination step. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing an example of a configuration of a main part of a display device according to a first embodiment of the present disclosure. [Diagram 2] 2 is a schematic diagram showing a divided display area obtained by dividing a display region of a liquid crystal panel included in the display device shown in FIG. 1 into a plurality of divided display areas. [Diagram 3] 2 is a schematic diagram showing a backlight area obtained by dividing the backlight included in the display device shown in FIG. 1 into a plurality of areas. FIG. [Figure 4] 2 is a diagram illustrating a flow of data generated in the display device according to the first embodiment of the present disclosure. FIG. [Diagram 5] 10 is a diagram showing a schematic diagram of the liquid crystal transmittance of the liquid crystal panel determined based on an input image and backlight data when all backlights are turned on at 100% output. FIG. [Figure 6] 10 is a diagram illustrating a relationship between an output value (backlight output value) in backlight data determined based on an input image and a liquid crystal transmittance of a liquid crystal panel determined based on the input image and the backlight data. FIG. [Figure 7] 10 is a diagram illustrating a relationship between an output value in backlight data determined based on an input image and a liquid crystal transmittance of a liquid crystal panel determined based on a processed image and the backlight data. FIG. [Figure 8] 11 is a graph showing an example of the relationship between an input signal indicating the magnitude of a luminance value of an input image and liquid crystal transmittance, based on a processed image displayed on the display device according to the first embodiment of the present disclosure. [Figure 9] 11 is a graph showing an example of the relationship between an input signal indicating the magnitude of a luminance value of an input image and liquid crystal transmittance, based on a processed image displayed on the display device according to the first embodiment of the present disclosure. [Figure 10] 11 is a graph showing an example of the relationship between an input signal indicating the magnitude of a luminance value of an input image and liquid crystal transmittance, based on a processed image displayed on the display device according to the first embodiment of the present disclosure. [Figure 11] 5 is a flowchart showing an example of a display control process of the display device according to the first embodiment of the present disclosure. [Figure 12] 11 is a block diagram showing an example of a main configuration of a display device according to a second embodiment of the present disclosure. FIG. [Figure 13]FIG. 11 is a diagram illustrating a schematic positional relationship between a display device according to a second embodiment of the present disclosure and a viewer. [Figure 14] FIG. 14 is a diagram showing an example of an image obtained by capturing the viewer shown in FIG. 13. [Figure 15] 10 is a flowchart showing an example of a display control process of a display device according to a second embodiment of the present disclosure. [Figure 16] FIG. 11 is a block diagram showing an example of a main configuration of a display device according to a third embodiment of the present disclosure. [Figure 17] FIG. 17 is a diagram illustrating a case where an input image received by the display device illustrated in FIG. 16 includes text. [Figure 18] 13 is a flowchart showing an example of a display control process of a display device according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments and modifications of the present disclosure will be described with reference to the drawings. In the following, the same or corresponding elements are given the same reference numerals throughout all the drawings, and their repeated description will be omitted. In addition, the embodiments and modifications described below are merely examples of the present disclosure, and the present disclosure is not limited to the embodiments and modifications. Even if it is not the embodiment or modification, various modifications can be made according to the design, etc., as long as it does not deviate from the technical idea of ​​the present disclosure.

[0010] [First embodiment] Hereinafter, the display device 1 according to the first embodiment of the present disclosure will be described in detail with reference to Figs. 1 to 4. Fig. 1 is a block diagram showing an example of a main configuration of the display device 1 according to the first embodiment of the present disclosure. Fig. 2 is a schematic diagram showing a divided display area 332 obtained by dividing the display region of the liquid crystal panel 32 included in the display device 1 shown in Fig. 1 into a plurality of areas. Fig. 3 is a schematic diagram showing a backlight area 331 obtained by dividing the backlight 34 included in the display device 1 shown in Fig. 1 into a plurality of areas. Fig. 4 is a diagram explaining the flow of data generated in the display device 1 according to the first embodiment of the present disclosure.

[0011] As shown in Fig. 4, the display device 1 displays an image 13 based on various input images 10, and includes a control unit 2, a display unit 3, a storage unit 4, and an optical sensor 5 (illuminance detection unit) as shown in Fig. 1. The display device 1 is, for example, a liquid crystal display.

[0012] The control unit 2 performs various controls on the various units included in the display device 1. The control unit 2 includes a backlight data generation unit 22 (brightness value determination unit), a liquid crystal data generation unit 23 (liquid crystal transmittance determination unit), and an image processing unit 24. In this embodiment, the backlight data generation unit 22, the liquid crystal data generation unit 23, and the image processing unit 24 are all configured by electronic circuits dedicated to the image processing of this embodiment.

[0013] In addition, when the control unit 2 is realized by an arithmetic processing device such as a CPU (Central Processing Unit), the CPU may be configured to read a program stored in the storage unit 4, for example, into a memory (not shown) and execute the program to realize the backlight data generating unit 22, the liquid crystal data generating unit 23, and the image processing unit 24. In addition, the program is not limited to the storage unit 4 described above, and may be recorded in a non-transitory recording medium such as an optical disk or a hard disk drive. The detailed configuration of the control unit 2 will be described later.

[0014] The storage unit 4 is a computer-readable recording medium, and can be realized by, for example, a ROM (Read Only Memory), etc. The storage unit 4 stores, for example, programs to be processed by the control unit 2, etc.

[0015] The display unit 3 displays a video 13 based on the input image 10 processed by the control unit 2. Specifically, the display unit 3 includes a panel drive unit 31, a liquid crystal panel 32, a backlight drive unit 33, and a backlight 34. The panel drive unit 31 and the backlight drive unit 33 constitute a display control unit 30.

[0016] The panel driving unit 31 controls the liquid crystal panel 32 to be driven based on the liquid crystal data 11 generated by the control unit 2 .

[0017] 2, the display area of ​​the liquid crystal panel 32 is divided into a matrix shape. Each area into which the display area is divided is referred to as a divided display area 332.

[0018] 3, the backlight 34 is divided into a plurality of backlight areas 331 whose luminance can be controlled independently. The backlight driving unit 33 controls the lighting of each of the plurality of backlight areas 331 in the backlight 34 based on the backlight data 12 (see FIG. 4) generated by the control unit 2. Each backlight area 331 may be an area constituted by one light source (e.g., an LED) or may be an area constituted by a plurality of light sources.

[0019] The display device 1 is configured to perform display control of a video 13 based on an input image 10 using a local dimming function that controls the lighting of each corresponding backlight area 331 for each divided display area 332 of the liquid crystal panel 32.

[0020] As shown in FIG. 4, when display processing is performed using the local dimming function, backlight data 12 for controlling the luminance of the backlight 34 is generated based on the luminance value (or pixel value) of the input image 10.

[0021] Based on this backlight data 12 and the luminance value of each pixel of the input image 10, liquid crystal data 11 for controlling the liquid crystal panel 32 is generated.

[0022] Then, panel driver 31 drives liquid crystal panel 32 with the output value indicated by liquid crystal data 11, and backlight driver 33 controls the lighting of each backlight area 331 based on backlight data 12 generated by controller 2. In this way, video 13 based on input image 10 is displayed.

[0023] (Control Unit Configuration) Next, the configuration of the control unit 2 included in the display device 1 will be described in detail with reference to Fig. 1 again. As described above, the control unit 2 includes the backlight data generation unit 22, the liquid crystal data generation unit 23, and the image processing unit 24.

[0024] The backlight data generating unit 22 determines the luminance value of each of the backlight areas 331 obtained by dividing the lighting area of ​​the backlight 34 into a plurality of areas based on the input image 10, and generates the backlight data 12.

[0025] Specifically, the backlight data generating unit 22 divides the input image 10 into regions corresponding to each divided display area 332, and determines the luminance value of each backlight area 331 according to the luminance value of each pixel included in each divided region (image area). The luminance value of the backlight area 331 may be determined based on the average luminance value of each pixel included in the image area, or may be determined based on the highest luminance value among the luminance values ​​of the pixels included in the image area. The backlight data generating unit 22 outputs the generated backlight data 12 to the backlight driving unit 33 and the liquid crystal data generating unit 23.

[0026] The liquid crystal data generating section 23 generates liquid crystal data 11 based on the input image 10 and the backlight data 12 generated by the backlight data generating section 22 .

[0027] Specifically, the liquid crystal data generation unit 23 calculates the luminance distribution of the backlight 34 from the backlight data 12 using a luminance spread function (PSF, Point Spread Function) that numerically represents the diffusion of light. The liquid crystal data generation unit 23 determines the output value (liquid crystal transmittance) of each pixel of the liquid crystal panel 32 by dividing the luminance value (normalized value) of each pixel of the input image 10 by the corresponding luminance value (normalized value) in the luminance distribution of the backlight 34, and generates the liquid crystal data 11 as shown in FIG. 4. The liquid crystal data generation unit 23 then outputs the generated liquid crystal data 11 to the panel drive unit 31.

[0028] The image processing unit 24 generates a processed image from the input image 10 based on the degree of brightness (illuminance) of the external environment of the display device 1 as environmental information indicating the viewing environment of the viewer who views the display device 1. That is, the image processing unit 24 checks whether there is a first area including pixels of the input image 10 whose luminance is medium luminance or more in the divided display areas 332 of the liquid crystal panel 32 corresponding to each backlight area 331. Note that in this embodiment, the medium luminance is a predetermined value in the range of 112 to 144 gradations, for example, when the maximum luminance is 255 gradations. The value of the medium luminance is appropriately set in the range of 112 to 144 gradations depending on the display characteristics or the dimensions of the display area of ​​the display device 1.

[0029] Then, when the first area is present, the image processing unit 24 generates a processed image in which the luminance of the first area is reduced based on the illuminance of the external environment.

[0030] More specifically, when the image processing unit 24 determines that the illuminance of the external environment of the display device 1 is darker than a predetermined value based on the detection result by the optical sensor 5, it generates a processed image in which the luminance value of the first area in the liquid crystal panel 32 is reduced to a first luminance value so that the liquid crystal transmittance of the first area becomes a first transmittance that is lower than the upper limit (100%).

[0031] Furthermore, when it is determined based on the detection result by the optical sensor 5 that the illuminance of the external environment of the display device 1 is brighter than a predetermined value, a processed image is generated in which the luminance value of the first area is set to a second luminance value higher than the first luminance value so that the liquid crystal transmittance of the first area is equal to or lower than the upper limit (100%) and has a second transmittance higher than the first transmittance.

[0032] Here, the processed image will be described in more detail with reference to Figs. 5 to 7. Fig. 5 is a diagram showing the liquid crystal transmittance of the liquid crystal panel 32 determined based on the input image 10 and the backlight data 12 when all backlights are turned on at 100% output. Fig. 6 is a diagram showing the relationship between the output value (backlight output value) in the backlight data 12 determined based on the input image 10 and the liquid crystal transmittance of the liquid crystal panel 32 determined based on the input image 10 and the backlight data 12. Fig. 7 is a diagram showing the relationship between the output value in the backlight data 12 determined based on the input image 10 and the liquid crystal transmittance of the liquid crystal panel 32 determined based on the processed image and the backlight data 12.

[0033] 5 to 7, it is assumed that the input image 10 includes pixels a, b, and c. The luminance values ​​of the pixels a, b, and c in the input image 10 are 0.2, 0.5, and 0.8, respectively. It is assumed that the pixels a, b, and c exist in image areas of the input image 10 corresponding to different backlight areas 331.

[0034] That is, Fig. 5 shows the liquid crystal transmittance of the liquid crystal panel 32 corresponding to each of the pixels a to c when the backlight output value is set so that the output value is 1.0 (100%) for all backlight areas 331 of the backlight 34. Fig. 6 shows the liquid crystal transmittance of the liquid crystal panel 32 corresponding to each of the pixels a to c when the backlight output value is set in the backlight areas 331 corresponding to each of the pixels a to c using the local dimming function.

[0035] As shown in FIG. 5, when the brightness value is output so that all backlight areas 331 of the backlight 34 have a value of 1.0, the brightness difference between each of pixels a to c in the input image 10 can be expressed by the difference in the liquid crystal transmittance of the liquid crystal panel 32 corresponding to each of pixels a to c.

[0036] 6, when the luminance value of the backlight area 331 corresponding to pixel a of the input image 10 is set to 0.4, the luminance value of the backlight area 331 corresponding to pixel b is set to 0.5, and the light luminance value of the backlight area 331 corresponding to pixel c is set to 0.6, the liquid crystal transmittances of the liquid crystal panels 32 corresponding to pixels a to c, respectively, are 0.5, 1.0, and 1.0. In this case, in order to fully express the luminance difference between pixels b and c, the liquid crystal transmittance of the liquid crystal panel 32 corresponding to pixel c needs to be 1.3, but the liquid crystal transmittance cannot be set to be greater than 1.0.

[0037] This situation, in which the liquid crystal transmittance reaches 100% (liquid crystal transmittance 1.0) and the luminance difference between pixel b and pixel c cannot be expressed sufficiently, is called saturation of the liquid crystal transmittance. When the liquid crystal transmittance is saturated, the liquid crystal panel 32 cannot express gradations with high accuracy.

[0038] Such saturation of liquid crystal transmittance may occur when there is a first area including pixels of input image 10 whose luminance is at least medium luminance (P1) or more in divided display area 332. For example, in a configuration in which backlight data generating unit 22 determines the luminance value of backlight area 331 based on the average luminance value of each pixel included in the image area of ​​input image 10, saturation of liquid crystal transmittance may occur when there is a first area including pixels of medium luminance or more whose luminance value is greater than the average luminance value.

[0039] Therefore, in the display device 1, when there is a first area including pixels of the input image 10 whose brightness is medium or higher, the image processing unit 24 generates a processed image in which the brightness of the first area is reduced so as to reduce the occurrence rate of saturation of the liquid crystal transmittance.

[0040] More specifically, for the divided display area 332 where saturation of the liquid crystal transmittance may occur, i.e., the first area, the image processing unit 24 generates a processed image in which the luminance values ​​of pixels (e.g., pixels b and c in FIG. 6) of the input image 10 that are equal to or greater than medium luminance (P1) are reduced so that the liquid crystal transmittance of the liquid crystal panel 32 is less than 100%. Then, the liquid crystal data generating unit 23 generates liquid crystal data 11 based on the processed image and the backlight data 12. The liquid crystal transmittance determined by this generated liquid crystal data 11 is not 100% as shown in FIG. 7, and can represent the difference in luminance value between pixel b and pixel c.

[0041] In addition, as shown in FIG. 8, when the luminance value of a pixel is equal to or greater than P1, the processed image generated by the image processing unit 24 is an image in which the relationship between the input signal indicating the magnitude of the luminance value of the input image 10 and the liquid crystal transmittance is such that the liquid crystal transmittance increases in a gradual curve as the magnitude of the input signal increases.

[0042] FIG. 8 is a graph showing an example of the relationship between the input signal indicating the magnitude of the luminance value of the input image 10 and the liquid crystal transmittance, based on the processed image displayed on the display device 1 according to the first embodiment of the present disclosure.

[0043] In Fig. 8, the vertical axis of the graph is a value indicating the liquid crystal transmittance, and the horizontal axis is a value indicating the input signal. In Fig. 8, the relationship between the input signal and the liquid crystal transmittance determined by the liquid crystal data 11 generated based on the input image 10 and the backlight data 12 is shown by a dashed line, and the relationship between the input signal and the liquid crystal transmittance determined by the liquid crystal data 11 generated based on the processed image and the backlight data 12 is shown by a solid line.

[0044] As shown in Figure 8, when the liquid crystal data generation unit 23 determines the liquid crystal transmittance based on the input image 10 and the backlight data 12, the liquid crystal transmittance increases monotonically as the input signal value increases, and when the input signal value becomes P2 or greater, saturation of the liquid crystal transmittance occurs in the liquid crystal panel 32.

[0045] On the other hand, when the liquid crystal data generating unit 23 determines the liquid crystal transmittance based on the processed image and the backlight data 12, the liquid crystal transmittance increases monotonically as the input signal value increases until the input signal value reaches P1, but once the input signal value exceeds P1, the liquid crystal transmittance rises in a gentle curve. Then, when the input signal value reaches P3 or higher, which is higher than P2, saturation of the liquid crystal transmittance occurs in the liquid crystal panel 32. That is, in the first area, for pixels of the input image 10 having a luminance of P1 or higher, the luminance is reduced so that the relationship between the input signal value and the liquid crystal transmittance forms a gentle curve as shown in FIG.

[0046] Therefore, when the liquid crystal data generation unit 23 determines the liquid crystal transmittance based on the processed image and the backlight data 12, it is possible to reduce the occurrence of a situation in which the difference in brightness between each pixel of the input image 10 cannot be expressed due to saturation of the liquid crystal transmittance.

[0047] However, when the liquid crystal data generating unit 23 determines the liquid crystal transmittance based on the processed image and the backlight data 12, the brightness of the image 13 displayed on the display unit 3 decreases.

[0048] Therefore, the display device 1 according to the present embodiment is configured to change the processed image generated by the image processing unit 24 in accordance with the illuminance of the external environment of the display device 1.

[0049] That is, in general, when the display device 1 is installed in a bright room, it is preferable to display the image 13 displayed on the display device 1 as brightly as possible so as not to be overwhelmed by the surrounding illuminance. On the other hand, when the display device 1 is installed in a dark room, the importance of the luminance of the image 13 displayed on the display device 1 is low, and rather, the fine gradation expression becomes more important.

[0050] In the display device 1, when the image processing unit 24 determines that the illuminance is darker than a predetermined illuminance based on the detection result by the optical sensor 5, it generates a processed image in which the relationship between the input signal value and the liquid crystal transmittance satisfies the relationship shown by the solid line (first curve) in Fig. 8. Note that the processed image in which the relationship between the input signal value and the liquid crystal transmittance satisfies the relationship shown by the first curve in Fig. 8 is referred to as a first processed image, and the mode in which the image processing unit 24 generates the first processed image is referred to as Mode A.

[0051] On the other hand, when the image processing unit 24 determines that the illuminance is brighter than the predetermined illuminance, it generates a processed image in which the relationship between the input signal value and the liquid crystal transmittance satisfies the relationship shown by the solid line (second curve) in Fig. 9. Note that the processed image in which the relationship between the input signal value and the liquid crystal transmittance satisfies the relationship shown by the second curve in Fig. 9 is referred to as a second processed image, and the mode in which the image processing unit 24 generates the second processed image is referred to as Mode B.

[0052] FIG. 9 is a graph showing an example of the relationship between the input signal indicating the magnitude of the luminance value of the input image 10 and the liquid crystal transmittance, based on the processed image displayed on the display device 1 according to the first embodiment of the present disclosure.

[0053] 9, the vertical axis represents values ​​indicating the liquid crystal transmittance, and the horizontal axis represents values ​​indicating the input signal. In Fig. 9, the liquid crystal transmittance determined by the liquid crystal data 11 generated based on the input image 10 and the backlight data 12 is indicated by a dashed dotted line, and the liquid crystal transmittance determined by the liquid crystal data 11 generated based on the processed image (second processed image) and the backlight data 12 is indicated by a solid line.

[0054] 9, in the second processed image, the liquid crystal transmittance increases monotonically as the input signal value increases until it reaches P1, but once it exceeds P1, it rises in a curve. Then, when the input signal value reaches P4 or more, saturation of the liquid crystal transmittance occurs in the liquid crystal panel 32. Note that P4 is a value greater than P2 and less than P3.

[0055] That is, in mode B, saturation of the liquid crystal transmittance occurs at a stage when the input signal value is smaller than in mode A. For this reason, in mode B, the occurrence of a situation in which the difference in luminance of each pixel of input image 10 cannot be expressed due to saturation of the liquid crystal transmittance occurs more frequently than in mode A, but the luminance of video 13 displayed on display device 1 is greater than in mode A.

[0056] For this reason, when the external environment of the display device 1 is darker than a predetermined illuminance, for example, in a dark room, the display device 1 can prioritize fine gradation expression over luminance for the image 13 displayed by the display device 1 in mode A. On the other hand, when the external environment of the display device 1 is equal to or higher than a predetermined illuminance, for example, in a bright room, the display device 1 can prioritize luminance over fine gradation expression for the image 13 displayed by the display device 1 in mode B.

[0057] The image processing unit 24 is configured to switch between mode A and mode B based on a predetermined illuminance, such that when the external environment is darker than a predetermined illuminance, mode A is selected, and when the brightness is equal to or higher than the predetermined illuminance, mode B is selected. Specifically, the switching between mode A and mode B can be performed using a weighting coefficient.

[0058] For example, the specified illuminance can be set to 100 lux, and if the illuminance detected by the optical sensor 5 is less than 100 lux, it is determined that the display device 1 is installed in a dark room and mode A is selected, and if the illuminance is greater than 100 lux, it is determined that the display device 1 is installed in a bright room and mode B is selected.

[0059] Alternatively, as shown in FIG. 10, a processed image may be generated that has a curve (third curve) that is located between the first and second curves using a weighting coefficient that varies according to the illuminance detected by the optical sensor 5.

[0060] FIG. 10 is a graph showing an example of the relationship between the input signal indicating the magnitude of the luminance value of the input image 10 and the liquid crystal transmittance, based on the processed image displayed on the display device 1 according to the first embodiment of the present disclosure.

[0061] In Fig. 10, the vertical axis indicates values ​​indicating liquid crystal transmittance, and the horizontal axis indicates values ​​indicating input signals. In Fig. 10, among the correspondence relationships between liquid crystal transmittance and input signals determined by liquid crystal data 11 generated based on a processed image and backlight data 12, a first curve is indicated by a solid line, a second curve is indicated by a two-dot chain line, and a third curve is indicated by a dashed line.

[0062] For example, the predetermined illuminance is 100 lux, and the weighting factor at this time is 0.5. When the illuminance is greater than 100 lux, the weighting factor is set to be greater than 0.5, and when the illuminance detected by the optical sensor 5 is 150 lux or greater, the weighting factor is set to be 1. When the illuminance is less than 100 lux, the weighting factor is set to be less than 0.5, and when the illuminance detected by the optical sensor 5 is 50 lux or less, the weighting factor is set to be 0. At this time, when the weighting factor is 0, mode A is selected, and when the weighting factor is 1, mode B is selected. When the weighting factor is greater than 0 and less than 1, a value between the first curve and the second curve obtained for each value of the input signal is linearly interpolated according to the magnitude of the weighting factor to obtain a third curve, and a processed image may be generated.

[0063] In addition, the weighting coefficient may change due to a change in the illuminance of the external environment of the display device 1, for example when switching from mode A to mode B, so that the processed image is generated so that the curve changes in stages from the first curve of the first processed image to the second curve of the second processed image.

[0064] (Display control process for display device) Next, a display control process of the display device 1 will be described with reference to Fig. 11. Fig. 11 is a flowchart showing an example of a display control process of the display device 1 according to the first embodiment of the present disclosure.

[0065] 11, the display device 1 receives an input image 10 (step S11). When the display device 1 receives the input image 10, the backlight data generating unit 22 determines the luminance of each of the multiple backlight areas 331 based on the input image 10 (step S12). Then, the display device 1 generates backlight data 12 based on the luminance of each of the multiple backlight areas 331 thus determined.

[0066] Next, based on the input image 10 and the backlight data 12, the image processing unit 24 checks whether or not there is a first area including pixels of the input image 10 whose luminance is equal to or greater than medium luminance in the divided display area 332 of the liquid crystal panel 32 (step S13). If the image processing unit 24 determines that there is no first area ("No" in step S13), the process proceeds to step S17, where the liquid crystal data generation unit 23 determines the liquid crystal transmittance in each of the divided display areas 332 based on the input image 10 and the backlight data 12.

[0067] On the other hand, if the image processing unit 24 determines that the first area exists, it determines whether or not the external environment of the display device 1 is darker than a predetermined illuminance based on the detection result of the optical sensor 5 (step S14). If the image processing unit 24 determines "Yes" in step S14, it generates a first processed image based on the input image 10 (step S15). On the other hand, if the image processing unit 24 determines "No" in step S14, it generates a second processed image based on the input image 10 (step S16).

[0068] In this manner, when the first processed image or the second processed image is generated, the liquid crystal data generation unit 23 determines the liquid crystal transmittance in the liquid crystal panel 32 based on the first processed image or the second processed image and the backlight data 12 (step S17), and generates liquid crystal data 11.

[0069] Then, the display control unit 30 performs display control of the display unit 3 based on the backlight data 12 and the liquid crystal data 11 (step S18). That is, the panel driving unit 31 controls driving of the liquid crystal panel 32 based on the liquid crystal data 11. Also, the backlight driving unit 33 controls lighting of the backlight 34 based on the backlight data 12.

[0070] As described above, the relationship between the input signal and the liquid crystal transmittance for the luminance values ​​of pixels that are equal to or greater than P1 in the processed image is a curved relationship, but it may also be a straight line. However, if it is a straight line, the relationship between the input signal and the liquid crystal transmittance will change significantly at the inflection point corresponding to P1, and the image 13 may be displayed unnaturally. For this reason, it is preferable that the relationship between the input signal and the liquid crystal transmittance for the luminance values ​​of pixels that are equal to or greater than P1 in the processed image is a curved relationship.

[0071] As described above, the display device 1 can identify the first area in which liquid crystal saturation may occur. Furthermore, the display device 1 can reduce the luminance of the image 13 displayed in the first area in accordance with the environmental information indicating the illuminance of the external environment of the display device 1. Therefore, the display device 1 can suppress the occurrence of saturation of the liquid crystal transmittance by taking into account the environmental information indicating the illuminance of the external environment of the display device 1.

[0072] Incidentally, the environmental information serving as a criterion for determining whether the display device 1 executes mode A or mode B is not limited to the above-mentioned information indicating the illuminance of the external environment of the display device 1. The environmental information may be, for example, information regarding the distance between the display device 1 and the viewer. In other words, when the distance between the display device 1 and the viewer is farther than a predetermined distance, it is preferable to display the image 13 displayed on the display device 1 as brightly as possible so that the image can be clearly seen from a distance. On the other hand, when the distance between the display device 1 and the viewer is closer than the predetermined distance, the importance of the luminance of the image 13 displayed on the display device 1 is low, and rather, the fine gradation expression is more important.

[0073] The configuration of a display device 200 according to a second embodiment, which executes mode A or mode B based on information relating to the distance between the display device 1 and the viewer as environmental information, will be described below with reference to FIGS.

[0074] [Second embodiment] Fig. 12 is a block diagram showing an example of a main configuration of a display device 100 according to a second embodiment of the present disclosure. Fig. 13 is a diagram showing a schematic diagram of a positional relationship between the display device 100 according to the second embodiment of the present disclosure and a viewer. Fig. 14 is a diagram showing an example of an image obtained by capturing the viewer shown in Fig. 13.

[0075] 12, the display device 100 according to the second embodiment differs from the display device 1 according to the first embodiment shown in FIG 1 in that it includes a distance measuring device 6 (distance detection unit) instead of the optical sensor 5. Other than that, the display device 100 according to the second embodiment has the same configuration as the display device 1 according to the first embodiment, so the same members are denoted by the same reference numerals and the description thereof will be omitted.

[0076] The distance measuring device 6 is a distance detection device that detects the distance from the display device 100 to the viewers watching the display device 100. The distance measuring device 6 can be, for example, an imaging device such as a camera provided in the display device 1. For example, when the distance measuring device 6 is an imaging device, the distance measuring device 6 can be provided in an outer frame portion surrounding the outer periphery of the liquid crystal panel 32 of the display device 100, as shown in FIG. 13. Then, the distance measuring device 6 captures an image including the viewers watching the display device 100 (viewers X and Y in the example of FIG. 13).

[0077] 14, the distance measuring device 6 extracts the facial images of the viewers X and Y from the captured image by using face recognition technology or the like. The distance measuring device 6 detects the distance from the display device 100 to the viewers X and Y from the size of the faces of the viewers X and Y in the entire captured image.

[0078] When there are multiple viewers watching the display device 100 as shown in Figures 13 and 14, the distance measuring device 6 selects the viewer who is closest to the display device 100 (viewer Y in the examples of Figures 13 and 14), and transmits distance information to the selected viewer to the control unit 2.

[0079] The distance measuring device 6 is not limited to the imaging device described above, and may be, for example, a distance measuring sensor that uses light, millimeter waves, or ultrasonic waves.

[0080] In the control unit 2, the image processing unit 24 checks whether or not there is a first area in the divided display area 332 of the liquid crystal panel 32 that includes pixels of the input image 10 whose luminance is equal to or greater than medium luminance.

[0081] In the case where the split display area 332 has a first area, the image processing unit 24 generates a processed image in which the luminance of the first area is reduced based on the distance to the viewer detected by the distance measuring device 6.

[0082] More specifically, when the image processing unit 24 determines that the distance from the display device 100 to the viewer is closer than a predetermined distance, it generates a processed image in which the luminance of the image area of ​​the input image 10 corresponding to the first area is reduced to a first luminance value so that the liquid crystal transmittance of the first area becomes a first transmittance that is smaller than the upper limit.

[0083] On the other hand, when the image processing unit 24 determines that the distance to the viewer is farther than a predetermined distance based on the detection result by the distance measuring device 6, it generates a processed image in which the brightness of the first area is a second brightness value greater than the first brightness value, so that the liquid crystal transmittance of the first area is equal to or lower than an upper limit and has a second transmittance greater than the first transmittance.

[0084] More specifically, the image processing unit 24 selects mode A when the distance between the display device 100 and the viewer is closer than a predetermined distance, and selects mode B when the distance is equal to or greater than the predetermined distance. Then, a processed image is generated according to either mode A or mode B. The generation of the processed image is similar to that of the display device 1 according to the first embodiment, and therefore a description thereof will be omitted.

[0085] The predetermined distance serving as a criterion for switching between Mode A and Mode B may be, for example, 100 cm. This predetermined distance is set appropriately depending on the display characteristics or the size of the display area of ​​the display device 100.

[0086] Incidentally, the display device 100 is configured to switch between modes A and B based on a predetermined distance, such that mode A is selected when the distance to the viewer is closer than a predetermined distance, and mode B is selected when the distance is equal to or greater than the predetermined distance. The display device 100 can switch between modes A and B by varying a weighting coefficient, similar to the display device 1 according to the first embodiment.

[0087] For example, the predetermined distance is 100 cm, and the weighting coefficient at this time is 0.5. Then, when the distance detected by the distance measuring device 6 is 100 cm or more, the weighting coefficient is set to be greater than 0.5, and when the distance detected by the distance measuring device 6 is 2 m or more, the weighting coefficient is set to be 1. Furthermore, when the distance is closer than 100 cm, the weight and coefficient are set to be smaller than 0.5, and when the distance detected by the distance measuring device 6 is 50 cm or less, the weighting coefficient is set to be 0.

[0088] At this time, if the weighting coefficient is 0, mode A is selected, and if the weighting coefficient is 1, mode B is selected. When the weighting coefficient is greater than 0 and smaller than 1, a third curve is obtained by linearly interpolating the value between the first curve and the second curve obtained for each magnitude of the input signal according to the magnitude of the weighting coefficient, and a processed image may be generated.

[0089] In addition, the weighting coefficient may change depending on the change in the distance between the display device 100 and the viewer, and the processed image may be generated so that, for example, when switching from mode A to mode B, the curve changes gradually from the first curve of the first processed image to the second curve of the second processed image.

[0090] (Display control process for display device) Next, a display control process of the display device 100 will be described with reference to Fig. 15. Fig. 15 is a flowchart showing an example of a display control process of the display device 100 according to the second embodiment of the present disclosure.

[0091] In the display control process of the display device 100 according to the second embodiment shown in FIG. 15, the processes from step S21 to step S23 and from step S25 to step S28 are similar to the processes from step S11 to step S13 and from step S15 to step S18 in the display control process of the display device 1 according to the first embodiment shown in FIG. 11, and therefore their description will be omitted.

[0092] That is, if it is determined in step S23 that there is a first area, the image processing unit 24 determines whether or not the distance from the display device 100 to the viewer is closer than a predetermined distance based on the detection result of the distance measuring device 6 (step S24). If the image processing unit 24 determines "Yes" in step S24, it generates a first processed image based on the input image 10 (step S25). On the other hand, if the image processing unit 24 determines "No" in step S24, it generates a second processed image based on the input image 10 (step S26).

[0093] As described above, the display device 100 can identify the first area where liquid crystal saturation may occur. Furthermore, the display device 1 can reduce the luminance of the image 13 displayed in the first area according to the environmental information indicating the distance between the display device 1 and the viewer. Therefore, the display device 1 can suppress the occurrence of saturation of the liquid crystal transmittance by taking into account the environmental information indicating the illuminance of the external environment of the display device 1.

[0094] [Third embodiment] Next, a display device 200 according to a third embodiment of the present disclosure will be described with reference to Fig. 16 and Fig. 17. Fig. 16 is a block diagram showing an example of a main configuration of the display device 200 according to the third embodiment of the present disclosure. Fig. 17 is a diagram showing a schematic diagram of a case where the input image 10 received by the display device 200 shown in Fig. 16 includes text.

[0095] As shown in FIG. 16, the display device 200 according to the third embodiment differs from the display device 1 according to the first embodiment shown in FIG. 1 in that it does not include an optical sensor 5. Also, the control unit 2 differs in that it has a text discrimination unit 25 that discriminates whether or not the image area of ​​the input image 10 corresponding to the split display area 332 that is the first area includes text as shown in FIG. 17. And, the image processing unit 24 differs in that, when the text discrimination unit 25 discriminates that the image area of ​​the input image 10 corresponding to the first area includes text, it selects mode A to generate a processed image (first processed image), and when it discriminates that the image area does not include text, it selects mode B to generate a processed image (second processed image). Note that the generation of the processed image is the same as that of the display device 1 according to the first embodiment, and therefore a description thereof will be omitted.

[0096] Except for the above points, the display device 200 has a similar configuration to the display device 1 according to the first embodiment, so the same members are given the same reference numerals and the description thereof will be omitted.

[0097] The text discrimination unit 25 of the control unit 2 discriminates whether or not text is included in the image area of ​​the input image 10 corresponding to the first area as described above, based on the characteristic information of the input image 10. This allows the display device 200 to determine whether the video 13 to be displayed in the first area is text. Note that the text discrimination unit 25 may be configured to learn in advance the feature amount of the text included in the input image 10 as the characteristic information of the input image 10, and to discriminate whether or not text is included in the image area of ​​the input image 10 corresponding to the first area. Alternatively, the text discrimination unit 25 may be configured to detect the presence or absence of text by edge detection from the frequency components of the input image 10 as the characteristic information of the input image 10, thereby discriminating whether or not text is included in the image area of ​​the input image 10 corresponding to the first area.

[0098] Incidentally, the image 13 displayed by the display device 200 may be a natural image or an image including text as shown in Fig. 17. Here, for the image of the text portion, fine gradation expression is more important than brightness so that the characters can be distinguished. On the other hand, when the image 13 is a natural image, brightness is important.

[0099] Therefore, in the control unit 2, the image processing unit 24 checks whether or not there is a first area in the divided display area 332 of the liquid crystal panel 32 that includes pixels of the input image 10 whose luminance is equal to or greater than medium luminance.

[0100] When the split display area 332 has a first area, the image processing unit 24 determines whether the image 13 to be displayed in the first area is text or not, also based on the input image 10. When the image 13 to be displayed in the first area is text, a first processed image is generated in which the luminance of the first area is reduced to a first luminance value so that the liquid crystal transmittance of the first area becomes a first transmittance that is smaller than the upper limit (100%).

[0101] On the other hand, when the image processing unit 24 determines that the image 13 to be displayed in the first area is not text, it generates a processed image in which the brightness of the first area is a second brightness value greater than the first brightness value, so that the liquid crystal transmittance of the first area is equal to or lower than an upper limit and has a second transmittance greater than the first transmittance.

[0102] More specifically, image processing unit 24 selects mode A when image 13 to be displayed in the first area is text, and selects mode B when image 13 is not text. Then, a processed image (first processed image or second processed image) corresponding to either mode A or mode B is generated. The generation of the processed image is similar to that of display device 1 according to the first embodiment, and therefore a description thereof will be omitted.

[0103] In addition, the display device 200 is configured to switch between modes A and B such that if the image 13 to be displayed in the first area is text, mode A is selected, and if it is not text, mode B is selected. The display device 200 can switch between modes A and B by varying the weighting coefficient in the same way as the display device 1 according to the first embodiment.

[0104] For example, in a configuration in which the text discrimination unit 25 learns in advance the features of the text contained in the input image 10 and discriminates whether or not the image area of ​​the input image 10 contains text, the weighting coefficient is varied according to the degree of certainty of the text discrimination, i.e., the judgment accuracy, so that the weighting coefficient is increased so as to approach 1 as the judgment accuracy decreases, and is set to be decreased so as to approach 0 as the judgment accuracy increases.

[0105] At this time, if the weighting coefficient is 0, mode A is selected, and if the weighting coefficient is 1, mode B is selected. When the weighting coefficient is greater than 0 and smaller than 1, a third curve is obtained by linearly interpolating the value between the first curve and the second curve obtained for each magnitude of the input signal according to the magnitude of the weighting coefficient, and a processed image may be generated.

[0106] (Display control process for display device) Next, a display control process of the display device 200 will be described with reference to Fig. 18. Fig. 18 is a flowchart showing an example of a display control process of the display device 200 according to the third embodiment of the present disclosure.

[0107] In the display control process of the display device 200 according to the third embodiment shown in FIG. 18, the processes from step S31 to step S33 and from step S36 to step S39 are similar to the processes from step S11 to step S13 and from step S15 to step S18 in the display control process of the display device 1 according to the first embodiment shown in FIG. 11, and therefore their description will be omitted.

[0108] That is, in step S33, if the image processing unit 24 determines that a first area exists, the text discrimination unit 25 determines, based on the input image 10, whether or not there is text in the image area of ​​the input image 10 corresponding to the first area (step S34).

[0109] If image processing unit 24 determines based on the discrimination result of text discrimination unit 25 that there is text in the image area of ​​input image 10 corresponding to the first area ("Yes" in step S35), it generates a first processed image based on input image 10 (step S36). On the other hand, if image processing unit 24 determines "No" in step S354, it generates a second processed image based on input image 10 (step S37).

[0110] As described above, the display device 200 can identify the first area where liquid crystal saturation may occur. Furthermore, the display device 200 can reduce the luminance of the image 13 displayed in the first area in accordance with the characteristic information of the input image 10. Therefore, the display device 1 can suppress the occurrence of saturation of the liquid crystal transmittance by taking into account the characteristic information of the input image 10. [Explanation of symbols]

[0111] 1 Display device 2. Control section 3 Display section 4 Storage section 5. Light Sensor 6 Ranging device 10 Input images 11 LCD data 12 Backlight Data 13 Video 22 Backlight data generator 23 Liquid crystal data generation section 24 Image Processing Section 25 Text discrimination section 30 Display control unit 31 Panel drive unit 32 Liquid crystal panel 33 Backlight driver 34 Backlight 100 display device 200 Display device 331 Backlight Area 332 Split display area

Claims

1. a brightness value determination unit that determines a brightness value for each of a plurality of backlight areas obtained by dividing a lighting area of ​​the backlight based on an input image; an image processing unit that generates a processed image in which the luminance value of the first area is reduced based on external environment information or characteristic information of the input image when a first area including a pixel of the input image having a luminance value of medium luminance or more is present in a divided display area of ​​a liquid crystal panel corresponding to each of the backlight areas; a liquid crystal transmittance determination unit that determines a liquid crystal transmittance in each of the divided display areas based on the processed image and the luminance value of each of the backlight areas determined by the luminance value determination unit; A display device comprising: a display control unit that controls display of the input image based on the brightness value of the backlight area determined by the brightness value determination unit and the liquid crystal transmittance determined by the liquid crystal transmittance determination unit.

2. an illuminance detection unit that detects illuminance of an external environment of the display device as the external environment information; The image processing unit includes:

2. The display device of claim 1, wherein when it is determined that the illuminance of the external environment is darker than a predetermined value based on the detection result by the illuminance detection unit, the processed image is generated in which the luminance value of the first area is reduced to a first luminance value so that the liquid crystal transmittance of the first area becomes a first transmittance that is smaller than an upper limit.

3. The image processing unit includes:

3. The display device of claim 2, wherein when it is determined that the illuminance of the external environment is brighter than a predetermined value based on the detection result by the illuminance detection unit, the processed image is generated such that the luminance value of the first area is a second luminance value greater than the first luminance value, so that the liquid crystal transmittance of the first area is equal to or lower than an upper limit and has a second transmittance greater than the first transmittance.

4. a distance detection unit that detects a distance to a viewer who views the display device as the external environment information; The image processing unit includes:

2. The display device of claim 1, wherein when it is determined that the distance to the viewer detected by the distance detection unit is closer than a predetermined distance, the processed image is generated in which the brightness value of the first area is reduced to a first brightness value so that the liquid crystal transmittance of the first area becomes a first transmittance that is smaller than an upper limit.

5. The image processing unit includes:

5. The display device of claim 4, wherein when it is determined that the distance to the viewer is farther than a predetermined distance, the processed image is generated such that the liquid crystal transmittance of the first area is equal to or lower than an upper limit and has a second transmittance greater than the first transmittance, and the processed image has a brightness value of the first area that is a second brightness value greater than the first brightness value.

6. a text determination unit that determines whether or not text is included in an image area of ​​the input image corresponding to the first area, as the characteristic information of the input image; 2. The display device of claim 1, wherein when the text discrimination unit determines that the image area of ​​the input image contains the text, the image processing unit generates the processed image in which the brightness value of the first area is reduced to a first brightness value so that the liquid crystal transmittance of the first area becomes a first transmittance that is smaller than an upper limit.

7. 7. The display device of claim 6, wherein when the text discrimination unit determines that the image area of ​​the input image does not contain the text, the image processing unit generates the processed image in which the brightness value of the first area is a second brightness value greater than the first brightness value, so that the liquid crystal transmittance corresponding to the first area is equal to or lower than an upper limit and has a second transmittance greater than the first transmittance.

8. The display device according to claim 1 , wherein the image processing unit generates the processed image by using a weighting factor that is set based on the external environment information or characteristic information of the input image.

9. The display device described in claim 8, wherein when the weighting coefficient changes, the image processing unit generates the processed image so that the luminance value of the processed image changes gradually from the luminance value of the processed image generated based on the weighting coefficient before the change to the luminance value of the processed image generated based on the weighting coefficient after the change.

10. A method for controlling a display device including a liquid crystal panel and a backlight, comprising the steps of: a brightness value determination step of determining a brightness value of each of a plurality of backlight areas obtained by dividing the illumination area of ​​the backlight based on an input image; an image generating step of generating a processed image in which the luminance value of the first area is reduced based on external environment information or characteristic information of the input image when a first area including pixels having a luminance value of medium luminance or higher is present in the divided display areas of the liquid crystal panel corresponding to each of the backlight areas; a liquid crystal transmittance determination step of determining a liquid crystal transmittance in each of the divided display areas based on the processed image and the luminance values ​​of each of the backlight areas determined in the luminance value determination step; A method for controlling a display device, comprising: a display control step for controlling display of the input image based on the brightness value of the backlight area determined in the brightness value determination step and the liquid crystal transmittance determined in the liquid crystal transmittance determination step.

Images