Display device and method for controlling the same

Abstract

To provide a display device capable of reducing the uncomfortable feeling of a viewer during low power consumption and a method for controlling the same.SOLUTION: A display device (10) comprises: a display unit (13) that displays a video; a control unit (17) that controls a display state at the display unit; and an acquisition unit (15) that acquires power-saving-related information regarding reduction of power consumption at the display unit. The control unit executes a switching process for switching an operation mode of the display unit from a normal mode to a power saving mode lower in power consumption than the normal mode at the display unit on the basis of the power-saving-related information acquired by the acquisition unit. The switching process includes a reduction step of reducing a light quantity at the display unit, and an adjustment step of adjusting a γ curve for converting the grayscale of a video signal for displaying at the display 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] There is a known technology for controlling the operation of an image display device depending on the viewing situation (see Patent Document 1). With this technology, when a captured image does not include the user's face, the luminance of the image display unit is reduced, thereby reducing power consumption. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-209739 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the luminance of the image display section is reduced, the viewer may feel that the screen he or she is watching has become dark, which may cause the viewer to feel uncomfortable.

[0005] An object of one embodiment of the present invention is to provide a display device and a control method for the display device in which a sense of discomfort felt by a viewer during low power consumption is reduced. [Means for solving the problem]

[0006] In order to solve the above problems, a display device according to one embodiment of the present invention comprises a display unit that displays an image, a control unit that controls a display state on the display unit, and an acquisition unit that acquires power saving related information related to reducing power consumption on the display unit, and the control unit executes a switching process to switch the operation mode of the display unit from a normal mode to a power saving mode in which the power consumption of the display unit is lower than that of the normal mode based on the power saving related information acquired by the acquisition unit, and the switching process includes a reduction process to reduce the amount of light of the display unit, and an adjustment process to adjust a gamma curve for converting the gradation of a video signal for display on the display unit. Effect of the Invention

[0007] According to one embodiment of the present invention, a display device and a control method for the display device that reduce discomfort felt by a viewer during low power consumption can be provided. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram illustrating a configuration of a display device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart illustrating a process flow in the control method for the display device according to the first embodiment of the present invention. [Diagram 3] FIG. 13 is a diagram illustrating an example of an adjusted gamma curve. [Figure 4] FIG. 13 is a diagram illustrating an example of an intermediate gamma curve. [Diagram 5] FIG. 11 is a block diagram illustrating a configuration of a display device according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a flowchart illustrating a process flow in a control method for a display device according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a block diagram illustrating a configuration of a display device according to a third embodiment of the present invention. [Figure 8] FIG. 11 is a flowchart illustrating a process flow in a control method for a display device according to a third embodiment of the present invention. [Figure 9] FIG. 11 is a block diagram illustrating a configuration of a display device according to a fourth embodiment of the present invention. [Figure 10] FIG. 13 is a diagram showing the relationship between a table and an image quality mode. [Figure 11] FIG. 13 is a diagram showing the relationship between a table and illuminance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [First embodiment] A first embodiment of the present invention will be described in detail below. Fig. 1 is a block diagram showing the configuration of a display device 10 according to the first embodiment. The display device 10 has a video signal processing unit 11, a driver 12, a display unit 13, a storage unit 14, a viewing status acquisition unit 15, and a control unit 17.

[0010] The display device 10 displays an image based on the image signal on the display unit 13. The display unit 13 is driven by the drive signal DS, and displays an image (for example, a moving image or a still image) represented by the image signal ISo.

[0011] Here, the display unit 13 has one or more light-emitting elements, and the control unit 17 reduces the light amount of the light-emitting elements to achieve power saving. The display unit 13 has a non-luminescent display device (for example, a liquid crystal display device: LCD) or a self-luminescent display device (for example, an organic electroluminescent display device: OLED). (1) When the display unit 13 is composed of a non-luminescent display device, the display unit 13 generally has a light source (backlight) for the non-luminescent display device. The backlight has one or more light-emitting elements. In the case of local dimming, the backlight has a plurality of light-emitting elements whose light amount can be controlled independently of each other. (2) When the display unit 13 is composed of a self-luminescent display device, the display unit 13 has a plurality of light-emitting elements whose light amount can be controlled independently of each other to form pixels. As described above, the one or more light-emitting elements function as a light source for the non-luminescent display device or as a self-luminescent display device. When the display unit 13 has a plurality of light-emitting elements whose light amount can be controlled independently of each other, the power consumption can be reduced (power saving) by reducing the light amount of some of the plurality of light-emitting elements.

[0012] The video signal processing unit 11 processes the video signal ISi (input video signal) based on the γ curve and outputs it to the driver 12 as a video signal ISo (output video signal). The driver 12 generates a drive signal DS for driving the display unit 13 based on the processed output video signal ISo. The video signal processing unit 11 may have a histogram generating unit that generates a histogram of gradations on an image (e.g., a frame image) represented by the video signal ISi. This gradation histogram can be used in the γ curve adjustment process (step S16a) described later.

[0013] The storage unit 14 can store one or more gamma curves or parameters representing these gamma curves. The storage unit 14 may store only one standard gamma curve, or may store multiple switchable gamma curves.

[0014] The viewing status acquisition unit 15 acquires viewing status information representing the viewing status of the viewer. The viewing status information is used in a switching process for switching the operation mode of the display unit 13 from a normal mode to a power saving mode in which the power consumption of the display unit 13 is smaller than that of the normal mode. In other words, the viewing status information is power saving related information related to reduction of power consumption in the display unit 13, and the viewing status acquisition unit 15 functions as an acquisition unit that acquires the viewing status information representing the viewing status of the viewer as power saving related information.

[0015] The viewing status acquisition unit 15 can use, for example, a sensor (an image sensor or a millimeter wave sensor, for example) that acquires state information of the viewer's appearance (e.g., face). The image sensor can capture an image of the viewer to acquire an image of the viewer. The millimeter wave sensor can acquire external appearance information of the viewer by transmitting and receiving electromagnetic waves such as millimeter waves. The viewing status information is, for example, the viewer's line of sight and facial orientation. Based on the viewing status information, the control unit 17 can determine whether the viewer is in a non-viewing state in which he or she is not watching the video displayed on the display unit 13.

[0016] This non-viewing state means a state in which the viewer is near the display unit 13 but not looking at the display unit 13, and is to be distinguished from "absence of viewer" in which the viewer is not near the display unit 13 (for example, a state in which the viewer has moved to another room such as a toilet). The non-viewing state includes a completely non-viewing state in which the viewer is not looking at the display unit 13 at all (for example, when the viewer is sleeping in front of the display device 10), as well as a substantially non-viewing state in which the viewer is not substantially looking at the display unit 13. The substantially non-viewing state includes a state in which the viewer occasionally looks at the image on the display unit 13 while doing something else (for example, reading, viewing on a smartphone) (so-called multitasking).

[0017] The control unit 17 can determine the absence of a viewer or a non-viewing state based on the viewing status information acquired by the viewing status acquisition unit 15. The control unit 17 can determine the absence of a viewer or a non-viewing state as follows. The control unit 17 can determine that the viewer is absent when it is unable to extract the appearance (e.g., face) of the viewer from the viewing status information. There is no absence of a viewer immediately after the start-up of the display device 10, but as time passes from the start-up of the display device 10, there may be an absence of a viewer. The control unit 17 extracts the direction of the viewer's gaze and the direction of the face from the viewing status information, and can determine that the viewer is in a non-viewing state when the viewer's gaze or face is not directed toward the display unit 13. For example, the non-viewing state can be determined when the viewer's face is facing downward. At this time, the control unit 17 may also determine that the viewer is in a non-viewing state (effectively non-viewing state) when the viewer's gaze or face is temporarily directed toward the display unit 13. "Temporarily" refers to when the viewer's gaze or face is continuously directed toward the display unit 13 for less than 10 seconds, for example.

[0018] The control unit 17 controls the display state of the display unit 13. The control unit 17 can reduce the power consumption of the display unit 13 by reducing the amount of light emitted by the display unit 13. When the display unit 13 is configured from a non-luminous display device, the control unit 17 reduces the amount of light emitted by the display unit 13 by reducing the amount of light emitted by the light-emitting element 132 (backlight). On the other hand, when the display unit 13 is configured from a self-luminous display device, the control unit 17 reduces the amount of light emitted by the display unit 13 by reducing the maximum current of the light-emitting element 132 (corresponding to a pixel of the self-luminous display device). That is, in the case of a self-luminous display device, the change range (maximum light amount or maximum brightness) of the light amount (brightness) of the light-emitting element 132 is limited. This is because, in the case of a self-luminous display device, the light-emitting element 132 corresponds to a pixel, and therefore the light amount of each light-emitting element 132(i) is not uniform but changes in response to the image.

[0019] (Display device 10 control method S10) The control method S10 of the display device 10 by the control unit 17 will be described below. Fig. 2 is a flow chart showing the flow of processing in the control method S10 of the display device 10. The control method S10 of the display device 10 will be described in detail below.

[0020] (1) Setting the γ curve (step S11) For example, when the display device 10 is started up, the control unit 17 sets a gamma curve (step S11). The control unit 17 may set the gamma curve to, for example, one standard gamma curve stored in the storage unit 14. That is, the setting process (step S11) also includes a case where the gamma curve to be set is specified. The gamma curve may be selected from a plurality of gamma curves stored in the storage unit 14. This selection may be based on, for example, a user or genre information of the video.

[0021] (2) Acquisition of viewing status information (step S11) The viewing status acquisition unit 15 executes an acquisition process (step S12) to acquire viewing status information indicating the viewing status of the viewer as power saving related information related to reduction of power consumption in the display unit 13. The viewing status information includes information on the viewer's line of sight or the viewer's face direction.

[0022] (3) Deciding the mode (normal mode, power saving mode) (step S13) The control unit 17 determines the mode of the display device 10 based on the viewing status information. This mode can be divided into a normal mode and a power saving mode, and the normal mode is selected when the display device 10 is started up. The normal mode is an operation mode in which the display device 10 is in a normal state. The power saving mode is an operation mode in which the power consumption of the display unit 13 is smaller than that in the normal mode.

[0023] The control unit 17 selects the normal mode when it is determined that the viewer is in a viewing state in which the viewer is viewing a video, and selects the power saving mode when it is determined that the viewer is in a non-viewing state in which the viewer is not viewing a video. The control unit 17 determines to switch from the normal mode to the power saving mode when the viewing state transitions from the non-viewing state to the viewing state, and determines to switch from the power saving mode to the normal mode when the non-viewing state transitions from the viewing state. For example, when the non-viewing state continues for a predetermined time after the viewing state, the control unit 17 determines to switch from the normal mode to the power saving mode. When the viewing state continues for a predetermined time after the non-viewing state, the control unit 17 determines to switch from the power saving mode to the normal mode.

[0024] Based on this determination, switching from the normal mode to the power saving mode (step S14a) or switching from the power saving mode to the normal mode (step S14b) is executed as follows.

[0025] (4) Switching to power saving mode (steps S14a to S16a) Switching from the normal mode to the power saving mode will now be described. The control unit 17 determines whether the viewer is in a non-viewing state where the viewer is not watching the video, and, for example, when the non-viewing state continues for a predetermined period of time, executes a switching process for switching the operation mode of the display unit from the normal mode to a power saving mode in which the power consumption of the display unit 13 is smaller than that in the normal mode (steps S14a to S16a).

[0026] This switching process includes a reduction process for reducing the amount of light from the display unit 13 (step S15a) and an adjustment process for adjusting a gamma curve for converting the gradation of a video signal for display on the display unit 13 (step S16a).

[0027] (4-1) Reduction process (step S15a) In the reduction process (step S15a), the amount of light of the display unit 13 is reduced, thereby reducing the power consumption (power saving) of the display unit 13. A large proportion of the power consumed by the display device 10 is the power required for emitting light in the display unit 13. Note that reducing the amount of light also includes setting the amount of light to zero.

[0028] When the display unit 13 includes a non-emissive display device and a light source (backlight) for the non-emissive display device, the control unit 17 reduces the amount of light from the backlight. When the display unit 13 includes a self-emissive display device, the control unit 17 reduces the maximum amount of light (or maximum brightness) of a light-emitting element of the self-emissive display device. More specifically, the control unit 17 reduces the maximum current supplied to the light-emitting element, and supplies a current equal to or less than the reduced maximum current to the light-emitting element, causing the element to emit light at an amount of light equal to or less than the maximum amount of light.

[0029] (4-2) Adjustment process (step S16a) In order to reduce the discomfort felt by the viewer due to the reduction in the amount of light of the display unit 13, a gamma curve adjustment process is executed. This adjustment process (step S16a) is preferably performed substantially simultaneously with the reduction process (step S15a). "Substantially simultaneously" refers to a time difference (e.g., 50 milliseconds or less) within which the viewer cannot individually recognize the reduction process (step S15a) and the adjustment process (step S16a).

[0030] Fig. 3 is a diagram showing an example of a gamma curve before and after adjustment. Graph G1 is a graph showing a comparison between the gamma curve γa before adjustment and the gamma curve γb after adjustment. Graph G2 shows the luminance (Ln+γa) in the normal mode and at the gamma curve γa before adjustment, the luminance (Ld+γa) in the power saving mode and at the gamma curve γa before adjustment, and the luminance (Ld+γb) in the power saving mode and at the gamma curve γb after adjustment.

[0031] That is, the luminance curves (Ln+γa), (Ld+γa), and (Ld+γb) respectively represent the luminance on the display unit 13 in the following (1), (2), and (3). (1): In normal mode (normal viewing), (2): When the amount of light of the backlight is reduced by 25%, and (3): When the amount of light of the backlight is reduced by 25% and the γ curve is adjusted. The luminance curve (Ld+γa) is darker in all gradation ranges compared to the normal mode (luminance curve (Ln+γa)) due to the reduction in the amount of light of the backlight, and as a result, the image tends to be difficult to see. As shown below, by adjusting the γ curve, the ease of viewing the image can be improved.

[0032] The gamma curve is an index for converting the grayscale of a video signal from an input grayscale Gi to an output grayscale Go. As shown in graph G1 of Fig. 3, the gamma curve γb after adjustment in the adjustment process (step S16a) has a larger output grayscale Go than the gamma curve γa before adjustment in the adjustment process in an input grayscale range that is larger than the first reference grayscale Gi1 and smaller than the second reference grayscale Gi2. For example, at an input grayscale i0, the output grayscale G0b of the gamma curve γb is larger than the output grayscale G0a of the gamma curve γa.

[0033] As shown in graph G2 of Figure 3, in the range from the first reference gradation Gi1 to the second reference gradation Gi2, the luminance L(Ld+γb) at the adjusted gamma curve γb at the reduced amount of light is greater than the luminance L(Ld+γa) at the reduced amount of light at the gamma curve γa before the adjustment.

[0034] By increasing the output gradation Go in the mid-tone region (for example, between the first reference gradation Gi1 and the second reference gradation Gi2), it is possible to suppress the decrease in luminance due to the decrease in the amount of light in the mid-tone region, and reduce the sense of incongruity in the image. In many cases, the gradation range of an image is concentrated in the mid-tone region, and the proportions of the low gradation region and the high gradation region are relatively small. For this reason, in general, by increasing the luminance of the image in the mid-tone region, it is possible to reduce the sense of incongruity in the image when the amount of light is reduced.

[0035] Here, in the range of input gradation Gi3 or less, the luminance L(Ld+γb) in the adjusted gamma curve γb in the reduced light amount is greater than the luminance L(Ln+γa) in the unadjusted gamma curve γb in the unreduced light amount. This contributes to improving the sense of contrast from low to intermediate gradations. That is, when the maximum value (YMAX) of the input gradation Gi is small and the entire screen is a dark image, it is possible to expand the dynamic range from the low to intermediate gradation regions to display a bright image with a sense of contrast. In this way, by adjusting the gamma curve, the luminance in the power saving mode may be greater than the luminance in the normal mode in some gradation regions.

[0036] When the gradation is expressed by 8 bits (0 to 255), the first reference gradation Gi1 may be, for example, 16 or more and 40 or less, for example, 25, and the second reference gradation Gi2 may be, for example, 180 or more and 210 or less, for example, 200. In response to this, the control unit 17 may determine the first reference gradation Gi1 and the second reference gradation Gi2 based on the video signal. The control unit 17 acquires, for example, the maximum gradation Gmax and the minimum gradation Gmin on the video represented by the video signal from the video signal processing unit 11 (particularly, the above-mentioned histogram generating unit), and determines the first reference gradation Gi1 and the second reference gradation Gi2 based on the maximum gradation Gmax and the minimum gradation Gmin. Then, the control unit 17 executes the adjustment process (step S16a) based on the determined first reference gradation Gi1 and second reference gradation Gi2.

[0037] Here, the control unit 17 may adjust the γ curve stepwise in the adjustment process (step S16a). FIG. 4 is a diagram showing an example of an intermediate γ curve. FIG. 4 shows an intermediate γ curve γc between the γ curves γa and γb before and after adjustment. That is, the control unit 17 may pass through the intermediate γ curve γc when transitioning from the γ curve γa to the γ curve γb. In this way, it is possible to reduce the sense of discomfort felt when transitioning between γ curves. Here, one γ curve γc is passed through, but multiple (n) γ curves γc1 to γ ​​curve γcn may also be passed through.

[0038] (5) Switching to normal mode (steps S14b to S16b) Switching from the power saving mode to the normal mode will now be described. For example, when a viewing state (where the viewer is watching a video) continues for a predetermined period of time after a non-viewing state, the control unit 17 executes a switching process for switching the operation mode of the display unit from the power saving mode to the normal mode (steps S14b to S16b).

[0039] This switching process includes an increase process (step S15b) for returning (increasing) the amount of light of the display unit 13 to the original amount of light, and a return process (step S16b) for returning the γ curve for converting the gradation of the video signal for display on the display unit 13 to the original γ curve γb. As a result, the power saving state is cancelled, and the display unit 13 displays an image at normal brightness. It is preferable that the return process (step S16b) is performed substantially simultaneously with the increase process (step S15a).

[0040] The above description is based on the assumption that the viewer is near the display device 10. In the absence of a viewer, i.e., the viewer is not near the display device 10, the following processing can be performed. In the absence of a viewer, a power saving mode similar to the non-viewing state may be set, but a high power saving mode with a higher degree of power saving than the non-viewing state may also be set. In the latter case, it is possible to differentiate the degree to which the light amount of the display unit is reduced between the power saving mode and the high power saving mode. For example, in the high power saving mode, the light amount of the display unit 13 is reduced compared to the power saving mode, and the light amount is set to zero, for example.

[0041] The display device 10 according to this embodiment switches the operation mode of the display device 10 based on viewing status information. When switching to the power saving mode, a reduction process (step S15a) for reducing the amount of light of the display unit 13 and an adjustment process (step S16a) for adjusting a gamma curve for converting the gradation of a video signal for display on the display unit 13 are executed. This makes it possible to reduce the sense of discomfort felt by the viewer when the amount of light is reduced.

[0042] Second Embodiment A second embodiment of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0043] 4 is a block diagram showing the configuration of a display device 10 according to the second embodiment. The display device 10 includes a video signal processor 11, a driver 12, a display unit 13, a storage unit 14, a power saving instruction acquisition unit 15a, and a control unit 17.

[0044] The power saving instruction acquiring unit 15a functions as an acquiring unit that acquires, as power saving related information, an instruction to reduce the power consumption of the display device 10 from a management system that manages the energy used in the home (for example, a home energy management system: HEMS). The home energy management system is, for example, a system that is installed in the home to manage the power consumption of electrical appliances in the home. For example, the home energy management system appropriately instructs electrical appliances with relatively high power consumption to reduce their power consumption in order to limit the power consumption in the home to a predetermined range.

[0045] (Display device 10 control method S20) The control method S20 of the display device 10 by the control unit 17 will be described below. Fig. 5 is a flow chart showing the flow of processing in the control method S10 of the display device 10, which is an example of the control method of the display device 10 by the display device 10.

[0046] The power saving instruction acquisition unit 15a acquires an instruction (power saving instruction) to reduce the power consumption of the display device 10 (step S21). The control unit 17 determines the power saving mode of the display device 10 based on the power saving instruction (step S13) and switches the display device 10 to the power saving mode (steps S14a to 16a). When the power saving instruction is released, the control unit 17 determines the normal mode of the display device 10 (step S13) and switches the display device 10 to the normal mode (steps S14b to 16b).

[0047] As described above, the display device 10 according to this embodiment switches the operation mode of the display device 10 based on a power saving instruction from the management system. That is, power saving in cooperation with other home electrical appliances is possible based on an instruction from the management system. When switching to the power saving mode, a reduction process (step S15a) for reducing the amount of light of the display unit 13 and an adjustment process (step S16a) for adjusting a gamma curve for converting the gradation of a video signal for display on the display unit 13 are executed. This reduces the sense of discomfort felt by the viewer when the amount of light is reduced.

[0048] Third embodiment A third embodiment of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0049] 5 is a block diagram showing the configuration of a display device 10 according to a third embodiment. The display device 10 includes a video signal processor 11, a driver 12, a display unit 13, a storage unit 14, a power pressure information acquisition unit 15b, and a control unit 17.

[0050] The power tightness information acquiring unit 15b functions as an acquiring unit that acquires power tightness information indicating that the power supply of a power company is tight from a broadcasting station as the power saving related information. When the power supply is tight relative to the power consumption in the power supply area, the power company provides the display device 10 with the power tightness information indicating in which area the power supply is tight via a medium such as a broadcasting station.

[0051] (Display device 10 control method S30) The control method S30 of the display device 10 by the control unit 17 will be described below. Fig. 7 is a flow chart showing the flow of processing in the control method S30 of the display device 10, which is an example of the control method of the display device 10 by the display device 10.

[0052] The power tightness information acquisition unit 15b acquires power tightness information indicating that the power supply is tight (step S31). The control unit 17 determines the power saving mode of the display device 10 based on the power tightness information (step S13) and switches the display device 10 to the power saving mode (steps S14a to 16a). When the power tightness is relieved, the control unit 17 determines the normal mode of the display device 10 (step S13) and switches the display device 10 to the normal mode (steps S14b to 16b).

[0053] As described above, the display device 10 according to this embodiment switches the operation mode of the display device 10 based on the power tightness information. That is, power saving corresponding to the tightness of the power supply from the power company is possible. When switching to the power saving mode, a reduction process (step S15a) for reducing the amount of light of the display unit 13 is performed, along with an adjustment process (step S16a) for adjusting a gamma curve for converting the gradation of a video signal for display on the display unit 13. This can reduce the sense of discomfort felt by the viewer when the amount of light is reduced.

[0054] [Fourth embodiment] A fourth embodiment of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0055] 9 is a block diagram showing the configuration of a display device 10 according to the fourth embodiment. The display device 10 includes a video signal processor 11, a driver 12, a display unit 13, a storage unit 14, a viewing condition acquisition unit 15, an illuminance information acquisition unit 16, and a control unit 17.

[0056] The illuminance information acquiring unit 16 is, for example, an illuminance sensor that acquires information on illuminance, which is the brightness of the environment in which the display device 10 is placed.

[0057] In the fourth embodiment, in setting the gamma curve (step S11), the gamma curve to be set is determined based on the type of image and illuminance information.

[0058] Here, the input video signal ISi has genre information that identifies the genre of the video, and the control unit 17 determines the gamma curve to be set based on the video genre information and environmental illuminance information.

[0059] This determination can be performed using table T stored in storage unit 14. In this case, table T preferably represents the relationship between the genre of the video, the illuminance, and the gamma curve. More specifically, the video signal IS includes genre information for identifying the genre of the video and format information for identifying the format of the video content, and table T represents the relationship between the image quality mode (corresponding to the genre of the video), the format, and the environmental illuminance, and the gamma curve.

[0060] 10 and 11 are diagrams showing an example of this table T. Table T is divided into a plurality of tables corresponding to image quality modes 1 to 9. Here, image quality modes 1 to 9 are divided into sports, movies, standard (e.g., news), etc., and are further divided into three corresponding to the formats of video content (SDR, HLG, PQ). As a result, the table is divided into 27 tables ij (1-1 to 1-3, 2-1 to 2-3, ..., 9-1 to 9-3) (1: integers 1 to 9, j: integers 1 to 3). As shown in FIG. 6, each table ij is divided into nine setting tables ij-1 to ij-9 according to viewing situation information (e.g., illuminance value). In this way, table T essentially represents the relationship between the genre and format of the video, the illuminance of the environment, and the gamma curve.

[0061] The control unit 17 can obtain the genre information and the format information from the video signal ISi, determine the image quality mode corresponding to the genre information, and select the table ij corresponding to the image quality mode and the format. For example, when the genre is sports and the format is SDR, the table 1-1 is selected, and when the genre is movies and the format is HLG, the table 2-2 is selected.

[0062] After that, parameters ij-1 to ij-9 are selected based on the table ij selected corresponding to the genre and format, and on the viewing situation information, and a gamma curve is determined.

[0063] According to the control method S40 of the display device 10, an appropriate gamma curve is determined (step S21) without the user being aware of the genre of the video, etc. For example, when a "sports" broadcast is being received, the gamma curve T1-1 is determined and adjusted, and a vivid and dynamic video appears.

[0064] As described above, in the display device 10 according to the present embodiment, the control unit 17 determines and sets the gamma curve based on the genre information and illuminance information of the image. This makes it possible to respond to changes in the image caused by the genre of the image and the brightness of the environment.

[0065] [Software implementation example] The functions of the display device 10 (hereinafter referred to as the "device") can be realized by a program for causing a computer to function as the device, and a program for causing a computer to function as each control block of the device (in particular, each part included in the control unit 17).

[0066] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program to realize each function described in each of the above embodiments.

[0067] The program may be non-transitory and may be recorded in one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be provided to the device via any wired or wireless transmission medium.

[0068] In addition, some or all of the functions of each of the control blocks can be realized by a logic circuit. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of the present invention. In addition, the functions of each of the control blocks can be realized by, for example, a quantum computer.

[0069] 〔summary〕 A display device (10) according to a first aspect of the present invention includes a display unit (13) that displays an image, a control unit (17) that controls the display state of the display unit, and an acquisition unit (15) that acquires power-saving related information related to reducing power consumption of the display unit, and the control unit executes a switching process for switching the operation mode of the display unit from a normal mode to a power-saving mode in which the power consumption of the display unit is smaller than that of the normal mode based on the power-saving related information acquired by the acquisition unit, and the switching process includes a reduction process for reducing the amount of light of the display unit, and an adjustment process for adjusting a gamma curve for converting the gradation of a video signal for display on the display unit. Thus, by executing the adjustment process together with the reduction process, it is possible to reduce the sense of discomfort felt by the viewer when switching to the power-saving mode.

[0070] A display device (10) according to aspect 2 of the present invention is in aspect 1, where the gamma curve is an index for converting the gradation of the video signal from an input gradation (Gi) to an output gradation (Go), and the gamma curve (γb) after adjustment by the adjustment process has a larger output gradation in an input gradation range that is larger than a first reference gradation (Gi1) and smaller than a second reference gradation (Gi2) compared to the gamma curve (γb) before adjustment by the adjustment process. This makes it possible to further reduce the sense of discomfort felt by the viewer when switching to the power saving mode by increasing the output gradation from the first reference gradation to the second reference gradation (intermediate gradation region) and increasing the luminance after the amount of light is reduced.

[0071] In a display device (10) according to aspect 3 of the present invention, in aspect 2, the control unit acquires a maximum gradation and a minimum gradation in an image represented by the video signal, determines the first reference gradation and the second reference gradation based on the maximum gradation and the minimum gradation, and executes the adjustment process based on the determined first reference gradation and second reference gradation. This makes it possible to further reduce the sense of discomfort felt by a viewer when switching to a power saving mode by setting an input gradation range based on the maximum gradation and the minimum gradation in the image.

[0072] A display device (10) according to a fourth aspect of the present invention is any one of the first to third aspects, in which the control unit adjusts the gamma curve in a stepwise manner in the adjustment process. This makes it possible to reduce the sense of discomfort felt by the viewer due to the adjustment of the gamma curve by adjusting the gamma curve in a stepwise manner.

[0073] A display device (10) according to a fifth aspect of the present invention is any one of the first to fourth aspects, in which the acquisition unit acquires viewing status information representing a viewing status of a viewer as the power saving related information, and the control unit determines whether the viewer is in a non-viewing state where the viewer is not watching a video based on the viewing status information, and executes the switching process when the non-viewing state continues for a predetermined time. As a result, when the non-viewing state continues for the predetermined time, the display device transitions to a power saving mode, thereby reducing power consumption.

[0074] In a display device (10) according to a sixth aspect of the present invention, in the fifth aspect, the viewing status information includes information on the viewer's line of sight or the direction of the viewer's face, and the control unit determines whether the viewer is in the non-viewing state based on the line of sight or the direction of the face. This makes it possible to accurately determine the viewer's non-viewing state, including multitasking, based on the viewer's line of sight or the direction of the face.

[0075] In the display device (10) according to aspect 7 of the present invention, in any one of aspects 1 to 4, the acquisition unit acquires, as the power saving related information, an instruction to reduce the power consumption of the display device from a management system that manages energy used in the home. This enables power saving in cooperation with other home electrical appliances based on the instruction from the management system.

[0076] A display device (10) according to an eighth aspect of the present invention is any one of the first to fourth aspects, in which the acquisition unit acquires, from a broadcast station, power tightness information indicating that the power supply from a power company is tight, as the power saving related information. This enables power saving in response to the tightness of the power supply from the power company.

[0077] A display device (10) according to a ninth aspect of the present invention is any one of the first to eighth aspects, in which the display unit has a plurality of light-emitting elements capable of controlling the light amounts independently of each other, and the control unit reduces the light amounts of some of the plurality of light-emitting elements in the reduction process, thereby enabling power saving by reducing the light amounts of some of the plurality of light-emitting elements.

[0078] A display device (10) according to a tenth aspect of the present invention is the display device of the ninth aspect, wherein the display unit has a non-emissive display device or a self-emissive display device, and the plurality of light-emitting elements function as a light source for the non-emissive display device or as the self-emissive display device. This enables power saving in both the non-emissive display device and the self-emissive display device.

[0079] A control method for a display device according to an eleventh aspect of the present invention is a control method for a display device having a display unit for displaying video, the control method including: an acquisition process for acquiring power-saving related information related to reduction in power consumption in the display unit; and a switching process for switching an operation mode of the display unit from a normal mode to a power-saving mode in which the power consumption of the display unit is smaller than that in the normal mode, the switching process including a reduction process for reducing the amount of light in the display unit, and an adjustment process for adjusting a gamma curve for converting the gradation of a video signal for display in the display unit. Thus, by executing the adjustment process together with the reduction process, it is possible to reduce the sense of discomfort felt by a viewer when switching to the power-saving mode.

[0080] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Furthermore, new technical features can be formed by combining the technical means disclosed in the respective embodiments. [Explanation of symbols]

[0081] 10 Display device 11 Video signal processing section 12 Drivers 13 Display section 14 Storage section 15 Viewing status acquisition unit 15a Power saving instruction acquisition section 15b Power Stress Information Acquisition Department 16 Illuminance information acquisition section 17 Control section

Claims

1. A display unit for displaying an image; A control unit that controls a display state of the display unit; An acquisition unit that acquires power saving related information related to reduction of power consumption in the display unit, The control unit, based on the power saving related information acquired by the acquisition unit, execute a switching process for switching the operation mode of the display unit from a normal mode to a power saving mode in which the power consumption of the display unit is smaller than that of the normal mode; The switching process includes: A reduction process for reducing the amount of light of the display unit; and an adjustment process for adjusting a gamma curve for converting a gradation of a video signal for display on the display unit.

2. the gamma curve is an index for converting the gradation of the video signal from an input gradation to an output gradation, 2. The display device of claim 1, wherein the gamma curve after being adjusted by the adjustment process has a larger output gradation in an input gradation range that is larger than a first reference gradation and smaller than a second reference gradation, compared to the gamma curve before being adjusted by the adjustment process.

3. The control unit is Obtaining a maximum gray scale and a minimum gray scale on an image represented by the video signal; determining the first reference gray level and the second reference gray level based on the maximum gray level and the minimum gray level; The display device according to claim 2 , wherein the adjustment process is executed based on the determined first reference gray scale and second reference gray scale.

4. The display device according to claim 1 , wherein the control unit adjusts the gamma curve in a stepwise manner in the adjustment process.

5. The acquisition unit acquires viewing status information representing a viewing status of a viewer as the power saving related information, The control unit is determining whether the viewer is in a non-viewing state where the viewer is not viewing a video based on the viewing status information; 5. The display device according to claim 1, wherein the switching process is executed when the non-viewing state continues for a predetermined time.

6. The viewing situation information includes information on the viewer's line of sight or the viewer's face direction, The display device according to claim 5 , wherein the control unit determines whether the display device is in the non-viewing state based on the line of sight or the face direction.

7. The display device according to any one of claims 1 to 4, wherein the acquisition unit acquires, as the power saving related information, an instruction to reduce the power consumption of the display device from a management system that manages energy used in the home.

8. The display device according to any one of claims 1 to 4, wherein the acquisition unit acquires, from a broadcasting station, power tightness information indicating that a power company's power supply is tight, as the power saving related information.

9. the display unit has a plurality of light-emitting elements each capable of controlling the amount of light independently of one another; The display device according to claim 1 , wherein the control unit reduces the amount of light of some of the plurality of light-emitting elements in the reduction process.

10. The display unit includes a non-emissive display device or a self-emissive display device, The plurality of light-emitting elements function as a light source for the non-emissive display device or as the self-emissive display device. The display device according to claim 9.

11. A method for controlling a display device having a display unit that displays an image, comprising the steps of: An acquisition process for acquiring power saving related information relating to reduction of power consumption in the display unit; A switching process of switching the operation mode of the display unit from a normal mode to a power saving mode in which the power consumption of the display unit is smaller than that of the normal mode, The switching process includes: A reduction process for reducing the amount of light of the display unit; and an adjustment process for adjusting a gamma curve for converting the gradation of a video signal for display on the display unit.

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