Signal processing device, signal processing method, and display device

Abstract

The present technology relates to a signal processing device, a signal processing method, and a display device that make it possible to suppress the temperature rise of a display panel. Provided is a signal processing device equipped with a signal processing unit that, when the brightness of an image signal is increased from a low brightness display signal to a high brightness display signal, acquires at least one information among a brightness increase time obtained by measuring the time during which the brightness on a display panel is increased, the temperature rise amount of the display panel, and the feature amount of the image signal corresponding to an image displayed on the display panel, and on the basis of the acquired information, adaptively controls a first gain for increasing the brightness of the image signal according to the degree of influence of temperature rise of the display panel. The present technology can be applied to, for example, a self-luminous display device.

Description

Technical Field

[0001] This technology relates to a signal processing apparatus, a signal processing method, and a display apparatus, and more particularly, to a signal processing apparatus, a signal processing method, and a display apparatus capable of suppressing a temperature rise of a display panel.

Background Art

[0002] In recent years, self-emitting display devices such as OLED display devices have been becoming mainstream as display devices for displaying images. For example, Patent Document 1 discloses a technology related to increasing the luminance of a display panel as a technology related to a display device such as a self-emitting display device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a display device, when increasing the luminance of a display panel, it is required to suppress a temperature rise of the display panel.

[0005] This technology has been made in view of such a situation, and is intended to suppress a temperature rise of a display panel.

Means for Solving the Problems

[0006] A signal processing apparatus according to one aspect of this technology acquires a luminance improvement time obtained by measuring a time for improving the luminance in a display panel having self-emitting elements, and information related to an amount of temperature rise of the display panel, and based on the acquired luminance improvement time and the information related to the amount of temperature rise, for increasing a video signal from a low-luminance display signal to a high-luminance display signal Brightness improvement gain to By adding it to the normal gain, the brightness of the video signal is increased. The system includes a signal processing unit that controls the display panel to suppress the temperature rise, and the signal processing unit calculates a first integration step value according to the level of the video signal, calculates a first integration value obtained by integrating the calculated first integration step value in the time axis direction at predetermined time intervals as information regarding the brightness improvement time, calculates a second integration step value for when integrating according to the load that increases due to the brightness increase, calculates a second integration value obtained by integrating the calculated second integration step value in the time axis direction at predetermined time intervals as information regarding the temperature rise amount Furthermore, if at least one of the first integrated value or the second integrated value exceeds a predetermined value, control is performed to reduce the brightness improvement gain. It is a signal processing device.

[0007] One aspect of this technology is a signal processing method in which a signal processing device acquires information on the brightness improvement time, which is the time it takes to improve the brightness of a display panel having a self-emissive element, and the amount of temperature rise of the display panel, and based on the acquired information on the brightness improvement time and the amount of temperature rise, the signal processing device increases the brightness of the video signal from a low-brightness display signal to a high-brightness display signal. Brightness improvement Gain, By adding it to the normal gain, the brightness of the video signal is increased. This includes controlling the display panel to suppress the temperature rise, calculating a first integration step value corresponding to the level of the video signal, accumulating the first calculated integration step value in the time axis direction at predetermined time intervals to calculate a first integrated value as information regarding the brightness improvement time, and calculating a second integration step value for accumulating in accordance with the load increased by the brightness increase, accumulating the second calculated integration step value in the time axis direction at predetermined time intervals to calculate a second integrated value as information regarding the temperature rise amount. Furthermore, if at least one of the first integrated value or the second integrated value exceeds a predetermined value, control is performed to reduce the brightness improvement gain. This is a signal processing method that further includes [the following].

[0008] In one aspect of this technology, a signal processing device and signal processing method are used to obtain information on the brightness improvement time, which is the time it takes to increase the brightness of a display panel having a self-emissive element, and the amount of temperature rise of the display panel. Based on the obtained information on the brightness improvement time and the amount of temperature rise, the device is used to increase the brightness of a video signal from a low-brightness display signal to a high-brightness display signal. Brightness improvement The gain is By adding it to the normal gain, the brightness of the video signal is increased. The display panel is controlled to suppress the temperature rise, a first integration step value is calculated according to the level of the video signal, a first integration value is calculated by integrating the calculated first integration step value in the time axis direction at predetermined time intervals, and this first integration value is calculated as information regarding the brightness improvement time, a second integration step value is calculated for when integration is performed according to the load that increases due to the brightness increase, and a second integration value is calculated by integrating the calculated second integration step value in the time axis direction at predetermined time intervals, and this second integration value is calculated as information regarding the temperature rise amount. If at least one of the first integrated value or the second integrated value exceeds a predetermined value, control is performed to reduce the brightness improvement gain. ru.

[0009] A display device according to one aspect of this technology comprises a signal processing unit for processing video signals and a panel unit including a display panel having a self-emissive element for displaying video corresponding to the video signals. The signal processing unit acquires information on the brightness increase time, which is the time it takes to increase the brightness of the display panel, and the amount of temperature rise of the display panel. Based on the acquired information on the brightness increase time and the amount of temperature rise, the signal processing unit increases the brightness of the video signal from a low-brightness display signal to a high-brightness display signal. Brightness improvement Gain, By adding it to the normal gain, the brightness of the video signal is increased. The signal processing unit controls the display panel to suppress the temperature rise, and further calculates a first integration step value according to the level of the video signal, and calculates a first integration value obtained by integrating the calculated first integration step value in the time axis direction at predetermined time intervals as information regarding the brightness improvement time, and calculates a second integration step value for when integrating according to the load that increases due to the brightness increase, and calculates a second integration value obtained by integrating the calculated second integration step value in the time axis direction at predetermined time intervals as information regarding the temperature rise amount. Furthermore, if at least one of the first integrated value or the second integrated value exceeds a predetermined value, control is performed to reduce the brightness improvement gain. It is a display device.

[0010] In one aspect of this technology, a display device acquires information on the brightness improvement time, which is the time it takes to increase the brightness of a display panel having a self-emissive element, and the amount of temperature rise of the display panel. Based on the acquired information on the brightness improvement time and the amount of temperature rise, the display device increases the brightness of the video signal from a low-brightness display signal to a high-brightness display signal. Brightness improvementThe gain is By adding it to the normal gain, the brightness of the video signal is increased. The display panel is controlled to suppress the temperature rise, a first integration step value is calculated according to the level of the video signal, a first integration value is calculated by integrating the calculated first integration step value in the time axis direction at predetermined time intervals, and this first integration value is calculated as information regarding the brightness improvement time, a second integration step value is calculated for when integration is performed according to the load that increases due to the brightness increase, and a second integration value is calculated by integrating the calculated second integration step value in the time axis direction at predetermined time intervals, and this second integration value is calculated as information regarding the temperature rise amount. If at least one of the first integrated value or the second integrated value exceeds a predetermined value, control is performed to reduce the brightness improvement gain. ru.

[0011] The signal processing device and display device, which are aspects of this technology, may be independent devices or internal blocks constituting a single device. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example of a brightness enhancement process. [Figure 2] This figure shows an example of displaying a repeating pattern of a high-brightness signal using a brightness enhancement process. [Figure 3] This diagram shows a comparative example of a 3-color lighting system and a 4-color lighting system. [Figure 4] This block diagram shows an example configuration of one embodiment of a display device to which this technology is applied. [Figure 5] This is a block diagram showing a detailed configuration example of the signal processing unit. [Figure 6] This diagram shows the relationship between the input video signal and the integration step. [Figure 7] This figure shows the relationship between the input video signal and the integrated value. [Figure 8] This figure shows an example of a method for measuring the temperature rise using a temperature rise measurement unit. [Figure 9] This figure shows an example of the cumulative step value corresponding to the load increase. [Figure 10] This figure shows the relationship between the amount of temperature rise and an example of the cumulative value. [Figure 11]It is a diagram showing a configuration example of one temperature sensor provided in a panel section. [Figure 12] It is a diagram showing a configuration example of a plurality of temperature sensors provided in a panel section. [Figure 13] It is a diagram showing an example of a video signal greatly affected by temperature rise. [Figure 14] It is a diagram showing the relationship between the color components and current values of each pixel. [Figure 15] It is a diagram showing an example of the setting of the gain with respect to the luminance improvement time. [Figure 16] It is a diagram showing an example of the setting of the gain with respect to the amount of temperature rise. [Figure 17] It is a diagram showing an example of the setting of the gain with respect to APL [Figure 18] It is a flowchart for explaining the flow of the luminance improvement gain control process.

Embodiments for Carrying Out the Invention

[0013] <1. Embodiments of the Present Technology>

[0014] As a technology for increasing the brightness of a display device such as an OLED display device, there is a technology for detecting that a video signal switches from a low-brightness display signal (low-brightness signal) to a high-brightness display signal (high-brightness signal) and controlling the luminance improvement gain based on the increasing integrated value (see Patent Document 1 above).

[0015] FIG. 1 shows an example of a brightness enhancement process to which such a brightness enhancement technology is applied. A in FIG. 1 shows the relationship between the input video signal and the integrated value by thick lines L11 and L12 on the same time axis.

[0016] B in FIG. 1 shows the relationship between the gain multiplied by the input video signal and the integrated value by thick lines L13 and L14 on the same time axis. C in FIG. 1 shows the relationship between the output video signal obtained by multiplying the input video signal and the gain and the integrated value by thick lines L15 and L16 on the same time axis.

[0017] When using the brightness enhancement process shown in Figure 1, it is possible to control the brightness enhancement period for each high-brightness signal. However, in patterns where high-brightness signals are displayed repeatedly, the brightness enhancement period essentially continues indefinitely.

[0018] Figure 2 shows an example of displaying a repeating pattern of a high-brightness signal after brightness enhancement processing. In Figure 2A, the relationship between the input video signal and the integrated value is shown by thick lines L21 and L22, where corresponding waveforms are repeated on the same time axis.

[0019] Figure 2B shows the relationship between gain and integrated value, indicated by thick lines L23 and L24, where corresponding waveforms are repeated on the same time axis. Figure 2C shows the relationship between output video signal and integrated value, indicated by thick lines L25 and L26, where corresponding waveforms are repeated on the same time axis.

[0020] Thus, when using a brightness enhancement process, if the pattern involves repeatedly displaying a high-brightness signal, the brightness enhancement period essentially continues indefinitely, which could cause the temperature of the display panel in the display device to rise.

[0021] Furthermore, because it only considers a single brightness enhancement period, there is a risk that the brightness enhancement process may be performed even when a high-load image is being displayed and the display panel is already hot.

[0022] Because of these issues, it is necessary to shorten the brightness enhancement period or lower the brightness enhancement gain to the point where the temperature rise of the display panel does not become a problem, which means that the effect of increasing brightness cannot be fully realized.

[0023] In OLED display devices, when the pixels arranged two-dimensionally on the OLED display panel are WRGB pixels, a W conversion (WCT: White Color Translation) is performed on the input RGB video signal, and a three-color illumination method is typically used in which one color from the subpixel W of each pixel and up to two colors from the subpixels R, G, and B emit light, for a total of three colors.

[0024] In such WRGB OLED display panels, subpixels W, unlike subpixels R, G, and B, do not pass through a color filter and are highly efficient. Therefore, there is a method to increase brightness by increasing the illumination level of subpixels W. With this method, the high efficiency due to the filterless nature of subpixels W, and the enlargement of the size of subpixels W, allow the current of the high-brightness subpixels W to be less than or equal to the maximum current of the single-color subpixels R, G, and B, thus reducing the problem of temperature rise in the OLED display panel.

[0025] On the other hand, in WRGB OLED display panels, after the illumination level of subpixel W has saturated, illuminating the unused subpixels R, G, and B results in a four-color illumination state, enabling even higher brightness. However, this increases the load by the three subpixels R, G, and B, and the impact on the temperature rise of the OLED display panel becomes more than three times greater than before, making the aforementioned problems more pronounced.

[0026] Figure 3 shows a comparative example of a 3-color and 4-color lighting method. In Figure 3, the input RGB video signal is represented as "Input," and the lighting of sub-pixels W, R, G, and B based on the video signal after W conversion is represented as "Output." Furthermore, the multipliers "×1," "×2," and "×3" indicate that the 4-color lighting method at "×3" is more affected by the temperature rise of the OLED display panel compared to the 3-color lighting methods at "×1" and "×2."

[0027] This technology proposes a method for solving the problem of temperature rise that arises when increasing the brightness of display panels as described above. The embodiments of this technology will be described below with reference to the drawings.

[0028] (Device configuration) Figure 4 shows an example configuration of one embodiment of a display device to which this technology is applied.

[0029] Display device 1 is a self-emissive display device such as an OLED display device having an OLED display panel. Display device 1 is configured as a television receiver or a display device.

[0030] In Figure 4, the display device 1 consists of a signal input unit 110, a signal processing unit 111, a panel drive unit 112, and a panel unit 113.

[0031] The signal input section 110 consists of a tuner connected to an antenna, a communication module that can connect to a communication network such as the Internet, or an input interface that conforms to a predetermined standard.

[0032] The signal input unit 110 supplies video signals of various types of content to the signal processing unit 111, such as broadcast content transmitted by terrestrial broadcasting or satellite broadcasting, communication content streamed via communication networks such as the Internet, or recorded content stored on recording media such as optical discs or semiconductor memory, or on recording devices.

[0033] The signal processing unit 111 performs video signal processing on the video signal of the content supplied from the signal input unit 110, and supplies the resulting video signal to the panel drive unit 112. This video signal processing includes a brightness enhancement process that converts the video signal from a low-brightness display signal (low-brightness signal) to a high-brightness display signal (high-brightness signal).

[0034] The panel drive unit 112 drives the panel unit 113 based on the video signal supplied from the signal processing unit 111.

[0035] The panel unit 113 includes a display panel such as an OLED display panel. The panel unit 113 displays images corresponding to various content images in accordance with the drive from the panel drive unit 112.

[0036] An OLED display panel is a display panel in which pixels, including OLED elements as self-luminescent elements, are arranged in a two-dimensional manner. An OLED (Organic Light Emitting Diode) is a light-emitting element with a structure in which an organic light-emitting material is sandwiched between a cathode and an anode, and it constitutes the pixels (display pixels) arranged in a two-dimensional manner on an OLED display panel.

[0037] In an OLED display panel, each pixel (display pixel) is composed of four subpixels: white (W), red (R), green (G), and blue (B) in the WRGB system, and three subpixels: red (R), green (G), and blue (B) in the RGB system.

[0038] Note that in the configuration shown in Figure 4, the minimum configuration units are shown for the sake of simplicity in explanation, but other circuits and devices such as an audio signal processing circuit that processes the audio signal and a speaker that outputs sound according to the audio signal may also be included.

[0039] Figure 5 shows a detailed configuration example of the signal processing unit 111 shown in Figure 4.

[0040] In Figure 5, the signal processing unit 111 includes a brightness improvement time measurement unit 131, a temperature rise amount measurement unit 132, an APL measurement unit 133, a brightness improvement gain calculation unit 134, an addition unit 135, and a multiplication unit 136.

[0041] In the signal processing unit 111, the input video signal from the signal input unit 110 is supplied to the brightness improvement time measurement unit 131, the temperature rise amount measurement unit 132, the APL measurement unit 133, and the multiplication unit 136, respectively.

[0042] The brightness improvement time measurement unit 131 performs brightness improvement time measurement processing based on the video signal input thereto, and supplies the resulting brightness improvement time measurement result to the brightness improvement gain calculation unit 134. In this brightness improvement time measurement processing, the time during which the brightness of the display panel is improved is measured. Details of the brightness improvement time measurement processing will be described later with reference to Figures 6 and 7.

[0043] The temperature rise measurement unit 132 performs temperature rise measurement processing based on the video signal input thereto and the brightness enhancement multiplier, and supplies the resulting temperature rise measurement result to the brightness enhancement gain calculation unit 134. As the brightness enhancement multiplier, a brightness enhancement multiplier corresponding to the gain multiplied by the input video signal is fed back and input. The temperature rise here is considered to be the short-term temperature rise.

[0044] Furthermore, the temperature rise measurement unit 132 can use the measurement results of the surface temperature of the display panel supplied from the panel drive unit 112 when performing the temperature rise measurement process. Details of the temperature rise measurement process will be described later with reference to Figures 8 to 12.

[0045] The APL measurement unit 133 performs APL measurement processing based on the video signal input thereto, and supplies the resulting APL measurement result to the brightness enhancement gain calculation unit 134. In this APL measurement processing, APL (Average Picture Level) is measured as a characteristic quantity of the video signal corresponding to the image displayed on the display panel. Details of the APL measurement processing will be described later with reference to Figure 13.

[0046] The brightness improvement gain calculation unit 134 is supplied with the brightness improvement time measurement result from the brightness improvement time measurement unit 131, the temperature rise amount measurement result from the temperature rise amount measurement unit 132, and the APL measurement result from the APL measurement unit 133. Based on the brightness improvement time, temperature rise amount, and APL measurement results, the brightness improvement gain calculation unit 134 performs brightness improvement gain calculation processing and supplies the resulting brightness improvement gain to the adder 135.

[0047] Furthermore, the brightness enhancement gain calculation unit 134 can use the measurement results of the current flowing through the display panel, supplied from the panel drive unit 112, when performing the brightness enhancement gain calculation process. Details of the brightness enhancement gain calculation process will be described later with reference to Figures 15 to 17.

[0048] The addition unit 135 adds the brightness enhancement gain from the brightness enhancement gain calculation unit 134 and the normal gain, and supplies the resulting high-brightness gain to the multiplication unit 136.

[0049] The normal gain is a gain applied to the input video signal, and it is a gain used to make the input video signal a high-brightness display signal. For example, the normal gain can be set to a brightness enhancement gain for the three-color illumination area of ​​the WRGB system, so that the input video signal is always made brighter.

[0050] Here, the brightness of the input video signal is further increased by adding an additional brightness enhancement gain to the normal gain. For example, by adding the brightness enhancement gain, it is possible to adaptively switch between the three-color and four-color illumination of the WRGB system. This additional brightness enhancement gain is adaptively controlled according to the measurement results of the brightness enhancement time, short-term temperature rise, APL, and current load.

[0051] The multiplier 136 multiplies the input video signal by the brightness enhancement gain from the adder 135 and supplies the resulting output video signal to the panel drive unit 112.

[0052] In Figure 5, the panel drive unit 112 can be equipped with a panel temperature measuring unit 151 and a panel current measuring unit 152.

[0053] The panel temperature measurement unit 151 consists of a temperature sensor and the like provided on the panel unit 113. The panel temperature measurement unit 151 measures the surface temperature of the display panel and supplies the measurement result to the temperature rise measurement unit 132 of the signal processing unit 111. An example of the temperature sensor configuration will be described later with reference to Figures 11 and 12.

[0054] The panel current measurement unit 152 consists of a current sensor and the like provided on the panel unit 113. The panel current measurement unit 152 measures the current applied to the display panel and supplies the measurement result to the brightness enhancement gain calculation unit 134 of the signal processing unit 111.

[0055] Note that the configuration of the signal processing unit 111 shown in Figure 5 is just one example, and its minimum configuration can include a luminance improvement time measurement unit 131, a luminance improvement gain calculation unit 134, an adder 135, and a multiplier 136.

[0056] Even with this minimal configuration, controlling the brightness enhancement gain makes it possible to control the duration of higher-than-normal brightness, such as when four colors are lit. Furthermore, by combining this minimal configuration control with control using other measurement results, it becomes possible to, for example, suppress temperature rise even with display patterns that are sensitive to temperature increases, or enhance the effect of high brightness when there is a temperature margin.

[0057] (Measurement of brightness improvement time) When performing brightness enhancement processing using additional brightness enhancement gains, the current load required for brightness enhancement is high, and this has a significant impact on the temperature rise of the display panel. Therefore, it is not possible to perform brightness enhancement processing for a long period of time in the same area (region) on the display panel screen. Thus, it is necessary to measure the brightness enhancement time for each predetermined area on the display panel screen and control the brightness enhancement gain according to that brightness enhancement time.

[0058] The brightness improvement time measurement unit 131 calculates an integrated step value corresponding to the input video signal level when measuring the brightness improvement time, and integrates this integrated step value in the time axis direction. The integrated value calculated in this way corresponds to the brightness improvement time.

[0059] Figure 6 shows the relationship between the input video signal and the integration step value, with the horizontal axis representing the input video signal and the vertical axis representing the integration step, indicated by the thick line L31. Figure 7 shows the relationship between the input video signal and the integration value on the same time axis, indicated by the thick lines L41 and L42. In other words, Figure 7 shows the integration process representing the brightness improvement time.

[0060] Thus, the integrated value calculated by the brightness improvement time measurement unit 131 corresponds to the brightness improvement time, and the brightness improvement gain calculation unit 134 can control an additional brightness improvement gain according to this brightness improvement time. In other words, processing can be performed here in the same way as the brightness improvement process using the brightness improvement technology shown in Figure 1.

[0061] The display panel's screen area can be, for example, an area obtained by dividing the entire screen into multiple areas of predetermined size in the vertical and horizontal directions. Specifically, it can be an area corresponding to divided area A in Figure 12, which will be described later.

[0062] (Measurement of temperature rise) As mentioned in the above problem, simply measuring the brightness enhancement period is insufficient, as temperature rise occurs when brightness enhancement processing is performed frequently, such as in repeating display patterns. Therefore, it is necessary to measure the amount of temperature rise caused by the brightness enhancement processing and feed it back into the brightness enhancement gain to keep the temperature rise below a certain level.

[0063] Figure 8 shows an example of a method for measuring the temperature rise using the temperature rise measurement unit 132. In Figure 8, the temperature rise measurement unit 132 includes an integrated step value calculation unit 141 and an integrated processing unit 142.

[0064] The integration step value calculation unit 141 receives the input video signal and the brightness enhancement multiplier. The integration step value calculation unit 141 calculates the step value for the integration process according to the increased load caused by the brightness enhancement process.

[0065] Here, in order to correlate with the temperature rise, the positive cumulative step value under high load conditions is set to be larger than a predetermined value to match the rapidly rising temperature under high load conditions, and the negative cumulative step value under low load conditions is set to be smaller than a predetermined value to match the slowly decreasing temperature under low load conditions, which are lower than the high load conditions. Figure 9 shows the relationship between the load increase and the cumulative step value, with the horizontal axis representing the load increase and the vertical axis representing the cumulative step, indicated by the thick line L51.

[0066] The integration processing unit 142 integrates the integration step values ​​along the time axis to calculate an integrated value correlated with the temperature rise. Figure 10 shows the relationship between the load increase and the integrated value on the same time axis using thick lines L61 and L62. In other words, Figure 10 shows the integration process considering the temperature rise, and the integrated value represents the amount of temperature rise associated with increased brightness.

[0067] The temperature rise measurement unit 132 performs these processes for each predetermined area on the display panel screen and calculates the cumulative value for each predetermined area, thereby detecting a state in which the high-brightness processing is concentrated in the same location (area) for a short period of time, causing the temperature to rise.

[0068] In this case, the area on the display panel screen can be, for example, an area obtained by dividing the entire screen into multiple areas of predetermined size in the vertical and horizontal directions. Specifically, it can be an area corresponding to divided area A in Figure 12, which will be described later.

[0069] While this process can detect temperature increases due to increased brightness, it does not take into account the temperature effects of normal video display or ambient temperature. Therefore, there is a possibility that the brightness enhancement process may be performed while the display panel is at a high temperature.

[0070] Therefore, accuracy can be further improved by performing video load prediction using signal processing, or by measuring the actual surface temperature of the display panel using a temperature sensor, and adding the temperature information obtained thereto to the cumulative value for each predetermined area on the display panel screen.

[0071] The temperature sensor may be attached to the panel unit 113 as supplementary information for load prediction by signal processing, or multiple temperature sensors may be attached to the panel unit 113 for the purpose of improving the accuracy of the supplementary information or for direct measurement without load prediction by signal processing.

[0072] Figure 11 shows an example configuration of a single temperature sensor provided on the panel section 113. In Figure 11, the temperature sensor 171 is mounted at a position corresponding to approximately the center of the display panel screen and measures the surface temperature of the display panel. Note that the temperature sensor 171 is not limited to the position corresponding to approximately the center of the screen, but may be mounted at other positions as well.

[0073] Figure 12 shows an example of the configuration of multiple temperature sensors provided on the panel section 113. In Figure 12, the entire screen area of ​​the display panel is divided into 4x9 regions of the same size in the vertical and horizontal directions, and a temperature sensor 171 is attached to each divided region. For the sake of explanation, dashed lines indicating the boundaries of the divided regions are drawn on the screen of the display panel.

[0074] In Figure 12, the numbers corresponding to the vertical and horizontal directions of divided region A are written in the upper left divided region A11 and the lower right divided region Aij on the display panel screen. In addition, the numbers corresponding to the vertical and horizontal directions of temperature sensor 171 are written in the upper left temperature sensor 171-11 and the lower right temperature sensor 171-ij.

[0075] However, in these notations, i represents the vertical number and j represents the horizontal number. In other words, although Figure 12 shows an example where the display panel screen is divided into 4x9 division areas, it is possible to divide it into i x j (i, j: integers greater than or equal to 1) division areas A, and the number of division areas A to which the temperature sensor 171 can be attached is arbitrary.

[0076] In Figure 12, the temperature sensor 171-11 measures the surface temperature of the divided region A11 on the display panel screen. Although this is repetitive and will be omitted from further explanation, other temperature sensors 171-ij also similarly measure the surface temperature of the divided region Aij corresponding to their mounting position.

[0077] The temperature sensor 171 in Figure 11 and the temperature sensors 171-11 to 171-ij in Figure 12 correspond to the panel temperature measurement unit 151 in Figure 5. When multiple temperature sensors 171-11 to 171-ij are installed, it is possible to measure the surface temperature of the display panel more accurately compared to when only one temperature sensor 171 is installed.

[0078] (APL measurement) APL (Average Picture Level) represents the average signal level within a target area on the display panel screen. When the entire display panel screen is in a high APL state, the total increase in load due to the brightness enhancement process becomes large, and because the original total load is also large, the impact of brightness enhancement on temperature rise becomes significant. A high APL state means that the APL value is higher than a predetermined value, that is, the signal level of the video signal is high.

[0079] On the other hand, when the entire display panel screen is in a low APL state, the total increase in load due to brightness enhancement processing is small, and the impact on the overall temperature rise of the screen is small. However, for video signals that are concentrated in one place on the screen, such as window signals, and have a locally high signal level, the impact on the temperature rise increases as the amount of brightness enhancement increases. A low APL state refers to a state in which the APL value is lower than a predetermined value, that is, a state in which the signal level of the video signal is low.

[0080] Figure 13 shows examples of video signals that are significantly affected by temperature rise. Figure 13A shows the case where the entire screen of the display panel displays an image corresponding to a video signal with a high signal level. Figure 13B shows the case where a localized area (the white area in the figure) approximately in the center of the screen of the display panel displays an image corresponding to a video signal with a high signal level.

[0081] In order to detect display patterns that have a significant impact on temperature rise and control the brightness enhancement gain, the APL measurement unit 133 measures the APL for the entire display panel screen or for each predetermined area.

[0082] In this case, the area on the display panel screen can be, for example, an area obtained by dividing the entire screen into multiple areas of predetermined size in the vertical and horizontal directions. Specifically, it can be an area corresponding to divided area A in Figure 12 described above.

[0083] (Measurement of current load) In OLED display panels, the current load on each pixel (OLED element) arranged in a two-dimensional array differs depending on its illumination level. Calculating the load increase due to the brightness enhancement process solely based on the APL measurement described above makes it difficult to account for these differences in current load. Therefore, measuring the current flowing through the OLED display panel using a current sensor or similar device can improve accuracy.

[0084] For example, in the case of video with a low current load, such as when many sub-pixels W are used even if the APL is high, the load increase due to the brightness enhancement processing will be small. In this case, the brightness enhancement gain calculation unit 134 should perform control that mitigates the suppression of the brightness enhancement gain according to the APL measurement result.

[0085] Figure 14 shows the relationship between the color components of each pixel and the current value. In Figure 14, the horizontal axis represents the subpixel color (White, Red, Green, Blue) and the color when two subpixels are lit (Yellow, Cyan, Magenta), and the vertical axis represents the panel drive current value. For each pixel, when subpixels R and G are lit, the color becomes yellow (Y); when subpixels R and B are lit, the color becomes magenta (M); and when subpixels G and B are lit, the color becomes cyan (C).

[0086] This bar graph shows that the panel drive current value differs for each color component. In particular, for yellow (Y), magenta (M), and cyan (C), the increase in panel drive current is significant because two subpixels are lit. Therefore, the brightness enhancement gain is controlled to take these factors into consideration.

[0087] (Calculation of brightness improvement gain) The brightness enhancement gain calculation unit 134 controls the brightness enhancement gain according to the degree of influence of temperature rise on each element (brightness enhancement time, temperature rise amount, APL, current load) to suppress the temperature rise of the display panel when increasing the brightness of the display panel. Examples of gain settings for each element are shown in Figures 15 to 17.

[0088] Figure 15 shows an example of setting the gain in relation to the brightness improvement time. In Figure 15, the horizontal axis represents the brightness improvement time (integrated value), and the vertical axis represents the brightness improvement time-linked gain.

[0089] In Figure 15, the gain corresponding to the brightness improvement time is shown by the thick line L81, which includes a downward-sloping straight line. This brightness improvement time-linked gain maintains 100% until the integrated value reaches a predetermined value, but after the integrated value exceeds the predetermined value, it gradually decreases at a predetermined slope, and after decreasing to 0%, it remains at 0%.

[0090] Figure 16 shows an example of setting the gain in relation to the temperature rise. In Figure 16, the horizontal axis represents the temperature rise (integrated value), and the vertical axis represents the temperature rise-linked gain.

[0091] In Figure 16, the gain corresponding to the temperature rise is shown by the thick line L82, which includes a downward-sloping straight line. This temperature rise gain remains at 100% until the integrated value reaches a predetermined value, but after the integrated value exceeds the predetermined value, it gradually decreases at a predetermined slope, and after decreasing to 0%, it remains at 0%.

[0092] Figure 17 shows an example of setting the gain for APL. In Figure 17, the horizontal axis represents APL, and the vertical axis represents the APL-linked gain. The APL value on the horizontal axis is set to a value in the range of 0% to 100%.

[0093] In Figure 17, the gain corresponding to the APL is shown by the thick lines L83 and L84, which include a downward-sloping straight line. Thick line L83 shows the APL-linked gain when the measured current load is high, and thick line L84 shows the APL-linked gain when the measured current load is low.

[0094] As shown by the thick lines L83 and L84, the APL-linked gain maintains 100% until the APL value reaches a predetermined value. After the APL value exceeds the predetermined value, it gradually decreases at a predetermined slope, and after decreasing to 0%, it remains at 0%.

[0095] Furthermore, compared to the thick line L84, the APL value at which the APL-linked gain decreases is smaller for the thick line L83, and when the measured current load is high, the APL-linked gain will decrease at a smaller APL value. Note that this example illustrates the case where the measurement of the current load is taken into account for the APL-linked gain, but it is also acceptable to set the APL-linked gain according to the APL without considering the current load.

[0096] The brightness enhancement gain calculation unit 134 sets these linked gains, and sets the final brightness enhancement gain as, for example, the value obtained by multiplying these linked gains, or the minimum value among these linked gains.

[0097] (Adaptive gain control) Figure 18 is a flowchart illustrating the flow of the brightness enhancement gain control process performed by the signal processing unit 111.

[0098] In step S11, the brightness improvement gain calculation unit 134 acquires at least one piece of information from among the measurement results of brightness improvement time, the measurement results of temperature rise, and the measurement results of APL. Here, as supplementary information for APL, the measurement results of the current flowing through the display panel may also be acquired.

[0099] In step S12, the brightness enhancement gain calculation unit 134 adaptively controls the brightness enhancement gain based on the acquired information, according to the degree of influence of temperature rise.

[0100] For example, in the brightness improvement gain calculation unit 134, the final brightness improvement gain is set by multiplying a brightness improvement time-linked gain corresponding to the brightness improvement time (integrated value), a temperature rise-linked gain corresponding to the temperature rise amount (integrated value), and an APL-linked gain corresponding to the APL.

[0101] As described above, when the signal processing unit 111 increases the brightness of a video signal from a low-brightness display signal to a high-brightness display signal, the brightness increase gain is adaptively controlled while estimating the degree of influence of the temperature rise of the display panel, based on at least one piece of information from among the brightness increase time measured for the time the brightness of the display panel is increased, the short-term temperature rise of the display panel, and the characteristic quantity of the video signal corresponding to the image displayed on the display panel (e.g., APL).

[0102] This solves the problem of temperature rise that arises when increasing the brightness of display panels, and suppresses the temperature rise of the display panel. In particular, in WRGB OLED display panels, even when further brightness is achieved by lighting up the unused sub-pixels R, G, and B after the illumination level of sub-pixel W has saturated, resulting in a four-color illumination state, it is possible to suppress the impact on the temperature rise of the OLED display panel.

[0103] <2. Variant>

[0104] In the above explanation, the signal processing unit 111 was described as a component of the display device 1, but it is also acceptable to consider the signal processing unit 111 as a standalone device and call it a signal processing device.

[0105] In the above explanation, the example given was that the display device 1 is a television receiver, but it is not limited to this and may be any other device such as a display device. Examples of such display devices include medical monitors, broadcast monitors, and digital signage displays.

[0106] Furthermore, the display device 1 may be used as a display unit for PCs (Personal Computers), tablet devices, smartphones, mobile phones, game consoles, head-mounted displays, in-vehicle equipment such as car navigation systems and rear-seat monitors, and wearable devices such as wristwatches and glasses.

[0107] In the above description, an OLED display device having an OLED display panel was used as an example of display device 1, but this technology can also be applied to other display devices such as self-emissive display devices having other self-emissive display panels.

[0108] In the above explanation, we showed a case where each pixel arranged two-dimensionally on the panel section 113 (display panel) is composed of four subpixels: white (W), red (R), green (G), and blue (B). However, the colors of the subpixels are not limited to these. For example, in each pixel, a subpixel of another color with the same high visual sensitivity as white (W) may be used instead of the white (W) subpixel.

[0109] In this specification, "OLED" may be read as "organic EL (Electro Luminescence)." For example, an OLED display device can also be said to be an organic EL display device. Also, since a video is composed of multiple image frames, "video" may be read as "image."

[0110] Furthermore, the embodiments of this technology are not limited to those described above, and various modifications are possible without departing from the spirit of this technology.

[0111] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0112] Furthermore, this technology can be configured as follows:

[0113] (1) When increasing the brightness of a video signal from a low-brightness display signal to a high-brightness display signal, at least one piece of information is acquired from among the brightness increase time measured for the time the brightness of the display panel is increased, the amount of temperature rise of the display panel, and the characteristic quantity of the video signal corresponding to the image displayed on the display panel. Based on the acquired information, a first gain for improving the brightness of the video signal is adaptively controlled according to the degree of influence of the temperature rise of the display panel. Equipped with a signal processing unit Signal processing device. (2) The signal processing unit further acquires the measurement results of the current flowing through the display panel. The signal processing device described in (1) above. (3) The signal processing unit achieves increased brightness of the video signal by additionally adding the first gain to the second gain used for increasing brightness. The signal processing device described in (1) or (2) above. (4) The signal processing unit uses a value corresponding to a linked gain linked to at least one of the following pieces of information: the brightness improvement time, the temperature rise amount, and the feature quantity, as the first gain. The signal processing device according to any one of (1) to (3) above. (5) The signal processing unit, when multiple interlocking gains exist, uses as the first gain a value obtained by multiplying the values ​​of the multiple interlocking gains, or the minimum value among the values ​​of the multiple interlocking gains. The signal processing device described in (4) above. (6) The signal processing unit, A cumulative step value is calculated according to the level of the aforementioned video signal. The calculated cumulative step values ​​are integrated along the time axis to calculate the cumulative value corresponding to the brightness improvement time. The signal processing device according to any one of (1) to (5) above. (7) The signal processing unit calculates an integrated value corresponding to the brightness improvement time for each predetermined area on the display panel screen. The signal processing device described in (6) above. (8) The signal processing unit, The integration step value for integration is calculated according to the load that increases due to the increased brightness. The calculated cumulative step value is accumulated in the time axis direction to calculate the cumulative value corresponding to the temperature rise. The signal processing device according to any one of (1) to (7) above. (9) The signal processing unit sets a positive integration step value greater than a predetermined value for high load conditions and a negative integration step value less than a predetermined value for low load conditions, which are lower than high load conditions, in order to correlate with the temperature rise. The signal processing device described in (8) above. (10) The signal processing unit calculates an integrated value corresponding to the temperature rise for each predetermined area on the display panel screen. The signal processing apparatus described in (8) or (9) above. (11) The signal processing unit adds information about the temperature obtained from predicting the load of the video or from the temperature sensor provided on the display panel to the cumulative value corresponding to the temperature rise. The signal processing device according to any one of (8) to (10) above. (12) One or more temperature sensors for measuring the surface temperature are provided for the display panel. The signal processing device described in (11) above. (13) The aforementioned feature is APL. The signal processing device according to any one of (1) to (12) above. (14) The signal processing unit performs the APL measurement for the entire screen of the display panel or for each predetermined area on the screen. The signal processing device described in (13) above. (15) The signal processing unit adds the measurement result of the current flowing through the display panel to the linked gain which is linked to the feature quantity. The signal processing device described in (4) above. (16) The signal processing unit When increasing the brightness of a video signal from a low-brightness display signal to a high-brightness display signal, at least one piece of information is acquired from among the brightness increase time measured for the time the brightness of the display panel is increased, the amount of temperature rise of the display panel, and the characteristic quantity of the video signal corresponding to the image displayed on the display panel. Based on the acquired information, a first gain for improving the brightness of the video signal is adaptively controlled according to the degree of influence of the temperature rise of the display panel. Signal processing method. (17) A signal processing unit that processes video signals, A panel unit having a display panel that displays an image corresponding to the aforementioned video signal. Equipped with, The signal processing unit, When increasing the brightness of the aforementioned video signal from a low-brightness display signal to a high-brightness display signal, at least one piece of information is acquired from among the brightness increase time measured for the time the brightness of the display panel is increased, the amount of temperature rise of the display panel, and the characteristic quantity of the video signal corresponding to the image displayed on the display panel. Based on the acquired information, a first gain for improving the brightness of the video signal is adaptively controlled according to the degree of influence of the temperature rise of the display panel. Display device. (18) The panel section has an OLED display panel. The display device described in (17) above. [Explanation of symbols]

[0114] 1 Display device, 110 Signal input unit, 111 Signal processing unit, 112 Panel drive unit, 113 Panel unit, 131 Brightness improvement time measurement unit, 132 Temperature rise amount measurement unit, 133 APL measurement unit, 134 Brightness improvement gain calculation unit, 135 Addition unit, 136 Multiplication unit, 151 Panel temperature measurement unit, 152 Panel current measurement unit, 171 Temperature sensor

Claims

1. The time taken to improve the brightness of a display panel having a self-emissive element, and information regarding the temperature rise of the display panel are obtained. Based on the acquired information regarding the brightness enhancement time and the amount of temperature rise, a brightness enhancement gain is added to the normal gain to increase the brightness of the video signal from a low-brightness display signal to a high-brightness display signal. This control enhances the brightness of the video signal while suppressing the temperature rise of the display panel. Equipped with a signal processing unit, The signal processing unit, A first integration step value is calculated according to the level of the video signal, and the first integrated value obtained by integrating the calculated first integration step value in the time axis direction at predetermined time intervals is calculated as information regarding the brightness improvement time. In accordance with the load increase due to the aforementioned increase in brightness, a second integration step value is calculated for the integration process, and the second integrated value obtained by integrating the calculated second integration step value in the time axis direction at predetermined time intervals is calculated as information regarding the temperature rise. If at least one of the first integrated value or the second integrated value exceeds a predetermined value, control is performed to reduce the brightness improvement gain. Signal processing device.

2. The signal processing unit, Further, the characteristic quantities of the video signal corresponding to the image displayed on the display panel, and the measurement results of the current flowing through the display panel are acquired. The brightness improvement gain is controlled based on the acquired information regarding the brightness improvement time, the temperature rise, the feature quantity, and the measurement results of the current. The signal processing apparatus according to claim 1.

3. The signal processing unit calculates the first integrated value for each predetermined area on the display panel screen. The signal processing apparatus according to claim 1.

4. When calculating the second integration step value, the signal processing unit sets a positive integration step value corresponding to the high load state to be larger than a predetermined value, and sets a negative integration step value corresponding to the low load state, which is lower than the high load state, to be smaller than a predetermined value, in order to correlate with the temperature rise. The signal processing apparatus according to claim 1.

5. The signal processing unit calculates the second integrated value for each predetermined area on the display panel screen. The signal processing apparatus according to claim 1.

6. The aforementioned feature is APL. The signal processing apparatus according to claim 2.

7. The signal processing unit performs the APL measurement for the entire screen of the display panel or for each predetermined area on the screen. The signal processing apparatus according to claim 6.

8. The signal processing unit To obtain information regarding the brightness improvement time, which is the time taken to improve the brightness of a display panel having a self-emissive element, and the amount of temperature rise of the display panel, Based on the acquired information regarding the brightness enhancement time and the amount of temperature rise, a brightness enhancement gain is added to the normal gain to increase the brightness of the video signal from a low-brightness display signal to a high-brightness display signal, thereby increasing the brightness of the video signal and controlling the display panel to suppress the temperature rise. Includes, A first integration step value corresponding to the level of the video signal is calculated, and the first integrated value obtained by integrating the calculated first integration step value in the time axis direction at predetermined time intervals is calculated as information regarding the brightness improvement time. In accordance with the load increase due to the aforementioned increase in brightness, a second integration step value is calculated for the integration process, and the second integrated value obtained by integrating the calculated second integration step value in the time axis direction at predetermined time intervals is calculated as information regarding the temperature rise. When at least one of the first integrated value or the second integrated value exceeds a predetermined value, control is performed to reduce the brightness improvement gain. A signal processing method that further includes this.

9. A signal processing unit that processes video signals, A panel section including a display panel having a self-emissive element that displays an image corresponding to the aforementioned video signal. Equipped with, The signal processing unit, The brightness improvement time, which is the time it takes to increase the brightness of the display panel, and information regarding the temperature rise of the display panel are obtained. Based on the acquired information regarding the brightness enhancement time and the amount of temperature rise, the system controls the display panel to enhance the brightness of the video signal by adding a brightness enhancement gain to the normal gain, thereby increasing the brightness of the video signal and suppressing the temperature rise of the display panel. The signal processing unit further, A first integration step value is calculated according to the level of the video signal, and the first integrated value obtained by integrating the calculated first integration step value in the time axis direction at predetermined time intervals is calculated as information regarding the brightness improvement time. In accordance with the load increase due to the aforementioned increase in brightness, a second integration step value is calculated for the integration process, and the second integrated value obtained by integrating the calculated second integration step value in the time axis direction at predetermined time intervals is calculated as information regarding the temperature rise. If at least one of the first integrated value or the second integrated value exceeds a predetermined value, control is performed to reduce the brightness improvement gain. Display device.

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