Control device

Abstract

To reduce time during which image quality of high-luminance image deteriorates.SOLUTION: A backlight drive control unit (8) of a control device (50) decreases an upper limit value of power at first speed and then increases the upper limit value at second speed higher than the first speed when supply of power to a backlight (9) is maintained for first predetermined time so that an image has luminance equal to or higher than a first predetermined value according to luminance information of the image.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device for controlling a backlight. [Background technology]

[0002] Patent Document 1 discloses a technology that increases or decreases the power supplied to a backlight based on two thresholds, and makes the time during which the power supplied to the backlight is decreased longer than the time during which the power supplied to the backlight is increased. This technology can reduce the possibility of a decrease in brightness while reducing the possibility of an increase in the temperature of the backlight's LEDs (Light-emitting diodes) and peripheral circuits. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-45000 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology of Patent Document 1, the amount of change per unit time when the power supplied to the backlight is reduced from one threshold value to the other threshold value is approximately the same as the amount of change per unit time when the power is increased from the other threshold value to one threshold value. Therefore, the time required to increase the power from the other threshold value to one threshold value is equivalent to the time required to decrease the power from the one threshold value to the other threshold value. Therefore, when an image with brightness above a predetermined value (a high-brightness image) is displayed, the quality of the high-brightness image deteriorates for a long time.

[0005] An object of one aspect of the present disclosure is to realize a control device that can reduce the time during which the image quality of a high-brightness image deteriorates. [Means for solving the problem]

[0006] In order to solve the above problem, a control device according to one embodiment of the present disclosure is a control device that controls a backlight, and includes a control unit that, when the supply of power to the backlight is maintained for a first predetermined time so that the image has a brightness equal to or greater than a first predetermined value, reduces the upper limit value of the power at a first speed and then increases it at a second speed greater than the first speed, in accordance with brightness information of the image. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, it is possible to reduce the time during which the image quality of a high-brightness image deteriorates. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a schematic configuration of a liquid crystal display device equipped with a control device according to a first embodiment of the present disclosure. [Figure 2] 5 is a flowchart illustrating an example of control performed by a backlight drive control unit of the control device. [Figure 3] 10 is a graph showing an example of a change in the power supplied to the backlight of the liquid crystal display device and a change in the upper limit of the power. [Figure 4] 10 is a graph showing an example of an increase in luminance per unit time corresponding to a second speed; [Figure 5] 10 is a graph showing an example of a change in the power supplied to the backlight of the liquid crystal display device and a change in the upper limit of the power. [Figure 6] 10 is a flowchart showing another example of control by the backlight drive control unit of the control device according to the second embodiment of the present disclosure. [Figure 7] 11 is a flowchart showing another example of control by the backlight drive control unit of the control device according to the third embodiment of the present disclosure. [Figure 8] 10 is a graph showing an example of a transition of an upper limit value of power supplied to a backlight of the control device. [Figure 9]10 is a graph showing another example of the transition of the upper limit value of the power supplied to the backlight of the control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Embodiment 1] A liquid crystal display device, which is one embodiment of a display device according to the present disclosure, will be described below.

[0010] <Configuration of Liquid Crystal Display Device> FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal display device 10 according to the first embodiment.

[0011] 1, a liquid crystal display device 10 of the present embodiment 1 includes an antenna 1, a tuner 2, a video processing unit 3, a display control unit 4, an area active control unit 5, a liquid crystal driving unit 6, a liquid crystal panel 7, a backlight drive control unit 8 (control unit), and a backlight 9. Of these, the display control unit 4, the area active control unit 5, the liquid crystal driving unit 6, and the backlight drive control unit 8 constitute a control device 50. The control device 50 is an example of a control device that controls the liquid crystal panel 7 and the backlight 9.

[0012] The liquid crystal panel 7 has (m×n) pixels arranged two-dimensionally. Each pixel includes an R display element that transmits red light, a G display element that transmits green light, and a B display element that transmits blue light. The R display element, G display element, and B display element are arranged side by side in the row direction, and these three display elements form one pixel. In the first embodiment, the liquid crystal panel 7 is exemplified as a three-color panel, but it may also be four or more colors.

[0013] The display screen of the liquid crystal panel 7 is divided into a plurality of parts, for example, (i x j) parts. Note that the term "part" here is defined for convenience to indicate a part of the display screen.

[0014] The liquid crystal driving unit 6 is a driving circuit for the liquid crystal panel 7. The liquid crystal driving unit 6 outputs a signal (voltage signal) that controls the light transmittance of the display element to the liquid crystal panel 7, based on display data (hereinafter referred to as liquid crystal data) that is output from the area active control unit 5 and that is used to drive the liquid crystal panel 7. The voltage output from the liquid crystal driving unit 6 is written to pixel electrodes (not shown) in the display elements of the liquid crystal panel 7, and the light transmittance of the display element changes according to the voltage written to the pixel electrodes.

[0015] The backlight 9 is provided on the rear side of the liquid crystal panel 7 and irradiates the rear side of the liquid crystal panel 7 with backlight. The backlight 9 has a plurality of LEDs arranged two-dimensionally as a light source. A predetermined number of these LEDs are grouped together to correspond to each of the (i x j) parts of the display screen of the liquid crystal panel 7. A group of a predetermined number of LEDs constitutes an LED unit. In other words, one LED unit corresponds to one part.

[0016] The backlight drive control unit 8 is a drive circuit that drives and lights each LED of the backlight 9 by PWM (Pulse Width Modulation) control. The backlight drive control unit 8 outputs a signal that controls the brightness (power) of each LED to the backlight 9 based on backlight control data (hereinafter referred to as LED data) used to drive the backlight 9, which is output from the area active control unit 5. The signal that controls the brightness of each LED is also called an SPI (Serial Peripheral Interface) signal.

[0017] The backlight drive control unit 8 further detects the LED_DUTY (hereinafter referred to as LED_DUTY) of each LED driven by PWM control. The backlight drive control unit 8 may control the power supplied to the backlight 9 according to the detected LED_DUTY. The backlight drive control unit 8 may detect the LED_DUTY of LEDs arranged in a predetermined arbitrary pattern (position) and control the power. The backlight drive control unit 8 performs power limiter control on the LED data output from the area active control unit 5 to determine the LED_DUTY.

[0018] The area active control unit 5 calculates the light transmittance of all display elements included in the liquid crystal panel 7 based on the input image generated by the display control unit 4, and generates the liquid crystal data representing the calculated light transmittance. Then, the area active control unit 5 outputs the generated liquid crystal data to the liquid crystal driving unit 6.

[0019] Furthermore, the area active control unit 5 calculates the brightness of the LEDs included in the LED unit corresponding to each part of the display screen of the liquid crystal panel 7, which is divided into (i × j) parts, based on the input image generated by the display control unit 4. Specifically, the area active control unit 5 calculates the brightness of all LEDs included in the backlight 9, and generates the above-mentioned LED data representing the calculated brightness of the LEDs. Then, the area active control unit 5 outputs the generated LED data to the backlight drive control unit 8.

[0020] This allows the backlight drive control unit 8 to control the LED_DUTY of each LED of the backlight 9 in accordance with the video signal. In other words, the backlight drive control unit 8 can control the supply of power to the backlight 9 in accordance with the LED data (luminance information of one frame of image).

[0021] The display control unit 4 generates an input image from the average luminance (APL) and luminance distribution of one frame of the image signal calculated by the upstream video processing unit 3, and outputs the generated input image to the area active control unit 5.

[0022] The video processing unit 3 calculates the average luminance (APL) and luminance distribution of one frame of the image from the video signal extracted by the tuner 2 from the radio waves received by the antenna 1, and outputs the calculated APL and luminance distribution to the display control unit 4.

[0023] <Control of backlight drive control unit> When an image having a brightness equal to or greater than a first predetermined value is input to the control device 50, the backlight drive control unit 8 supplies power to the backlight 9 so that the image has a brightness equal to or greater than the first predetermined value. When the brightness of a predetermined number of LEDs among the brightnesses of the multiple LEDs indicated in the LED data indicates a brightness equal to or greater than the first predetermined value, the backlight drive control unit 8 supplies power to the backlight 9. The first predetermined value and the predetermined number can be set arbitrarily. An image having a brightness equal to or greater than the first predetermined value may be referred to as a high-brightness image.

[0024] Furthermore, when an image having a luminance less than a second predetermined value is input to the control device 50, the backlight drive control unit 8 supplies power to the backlight 9 so that the image has a luminance less than the second predetermined value. When the luminance of a predetermined number of LEDs among the luminances of the multiple LEDs indicated in the LED data indicates a luminance less than the second predetermined value, the backlight drive control unit 8 supplies power to the backlight 9. The second predetermined value and the predetermined number can be set arbitrarily. An image having a luminance less than the second predetermined value may be referred to as a low-luminance image.

[0025] The second predetermined value is a lower brightness than the first predetermined value. For example, the first predetermined value may be approximately 1100 nits, and the second predetermined value may be approximately 900 nits. The two predetermined numbers may be the same or different. The LED used to determine the first predetermined value and the LED used to determine the second predetermined value may be the same or different.

[0026] Furthermore, when the control device 50 receives an average luminance equal to or less than a threshold value indicating the limit value of the power limiter and a high gradation signal equal to or greater than a certain value from the luminance distribution of the input gradation, the backlight drive control unit 8 may supply power so that the image has a luminance equal to or greater than a first predetermined value. The threshold value can be set arbitrarily. If the threshold value is set to, for example, 35%, and the control device 50 receives an average luminance of, for example, 30% and a high gradation signal equal to or greater than 800 in 10-bit gradation, the backlight drive control unit 8 may supply power so that the image has a luminance equal to or greater than the first predetermined value. Note that this input determination is performed by the display control unit 4.

[0027] Hereinafter, the control of the backlight drive control unit 8 of this embodiment will be described with reference to FIGS.

[0028] <Power upper limit control> FIG. 2 is a flowchart showing an example of control by the backlight drive control unit 8.

[0029] 2, the backlight drive control unit 8 determines whether the brightness of a predetermined number of LEDs indicated in the LED data is equal to or greater than a first predetermined value (S1). If the backlight drive control unit 8 determines that the brightness of a predetermined number of LEDs indicated in the LED data is equal to or greater than the first predetermined value (YES in S1), the backlight drive control unit 8 determines whether a first predetermined time has elapsed since the backlight drive control unit 8 started to continuously receive the LED data (S2). The first predetermined time may be a cumulative time.

[0030] In the processes of S1 and S2, the backlight drive control unit 8 determines whether LED data indicating that the brightness of a predetermined number of LEDs is equal to or greater than a first predetermined value has been received for a first predetermined time. That is, the backlight drive control unit 8 determines whether the supply of power to the backlight 9 has been maintained for the first predetermined time so that the image has a brightness equal to or greater than the first predetermined value. In other words, the backlight drive control unit 8 determines whether a high-brightness image will be displayed for the first predetermined time.

[0031] When the backlight drive control unit 8 determines that the first predetermined time has elapsed (YES in S2), it reduces the upper limit of power supplied to the backlight 9 (hereinafter referred to as the upper limit of power) at a first speed (S3). The backlight drive control unit 8 determines whether the upper limit of power has been reduced to a preset minimum value (S4). The backlight drive control unit 8 is capable of reducing the upper limit of power to a preset minimum value.

[0032] Furthermore, after starting the process of S3, the backlight drive control unit 8 determines whether the brightness of a predetermined number of LEDs indicated in the LED data is less than a second predetermined value (S5, S6). In other words, the backlight drive control unit 8 determines whether a state has been reached where the display should be switched to a low-brightness image. If the backlight drive control unit 8 determines that the brightness of a predetermined number of LEDs indicated in the LED data is less than the second predetermined value (YES in S5, YES in S6), it increases the upper limit of power at a second speed that is greater than the first speed (S7). That is, in S7, the backlight drive control unit 8 reduces the upper limit of power at the first speed, and then increases it at the second speed that is greater than the first speed.

[0033] If the results of S5 and S6 are YES, the backlight drive control unit 8 starts lowering the upper limit of power at the first speed (after the process of S3 starts), and then increases the upper limit of power at the second speed when switching the power supply so that the image has brightness less than the second predetermined value. In this embodiment, the backlight drive control unit 8 increases the upper limit of power at the second speed when switching the power supply to a value lower than the preset minimum value (when switching the display from a high-brightness image to a low-brightness image) as the power supply switching control.

[0034] The timing of increasing the brightness at the second speed also includes the timing of switching the display from a high-brightness image to a low-brightness image due to the switching of the power supply. Furthermore, the timing of increasing the brightness at the second speed does not have to be simultaneous with the timing of switching the power supply or the timing of switching the display from a high-brightness image to a low-brightness image. For example, the timing may be after a predetermined time (e.g., several seconds) has elapsed since receiving LED data indicating that the brightness of a predetermined number of LEDs is less than a second predetermined value, since switching the power supply, or since switching the display from a high-brightness image to a low-brightness image.

[0035] After starting the process of S7, the backlight drive control unit 8 determines whether the upper limit value of power has been increased to a preset maximum value (S8). If the backlight drive control unit 8 determines that the upper limit value of power has been increased to the preset maximum value (YES in S8), it ends this process. On the other hand, the backlight drive control unit 8 continues the processes of S7 and S8 until it determines that the upper limit value of power has been increased to the preset maximum value (NO in S8).

[0036] In addition, the backlight drive control unit 8 continues the process in S5 (if NO in S5) until it determines that the brightness of the predetermined number of LEDs indicated in the LED data is less than the second predetermined value (until the control device 50 accepts input of a low-brightness image). In other words, the backlight drive control unit 8 maintains the upper limit of power at the minimum value until it receives LED data indicating that the brightness of the predetermined number of LEDs is less than the second predetermined value (while it continues to receive LED data indicating that the brightness of the predetermined number of LEDs is equal to or greater than the first predetermined value). However, in the state of NO in S5, the backlight drive control unit 8 may increase the upper limit of power at a second speed to a predetermined value (for example, a first threshold value described below) that is less than the maximum value.

[0037] Furthermore, in the processing of S6, the backlight drive control unit 8 continues the processing of S3, S4 and S6 until it determines that the brightness of the predetermined number of LEDs indicated in the LED data is less than the second predetermined value or until it determines YES in S4.

[0038] Furthermore, if the backlight drive control unit 8 determines in the process of S1 that the brightness of the predetermined number of LEDs indicated in the LED data is less than the first predetermined value (NO in S1), it does not perform this process.Furthermore, the backlight drive control unit 8 also does not perform this process if it has not continuously received LED data indicating that the brightness of the LEDs is equal to or greater than the first predetermined value for the first predetermined time.

[0039] After completing this process, the backlight drive control unit 8 may continue to execute the process of S1. In this case, the setting of the first predetermined time in the process of S2 may be changed.

[0040] <Control of power and its upper limit> Fig. 3 is a graph showing an example of the transition of the power (LED brightness) supplied to the backlight 9 and the transition of the upper limit value of the power. Reference numeral 1001 in Fig. 3 is a graph showing the two transitions under the control of the backlight drive control unit 8, and reference numeral 1002 is a graph showing the two transitions under the control of the backlight drive control unit as a comparative example. Fig. 3 also shows the transition of the temperature of the backlight 9.

[0041] In FIG. 3, the vertical axis indicates the power (LED brightness) supplied to the backlight 9, and the horizontal axis indicates time. Furthermore, "POWER MAX" in FIG. 3 indicates the maximum value of power supplied to the backlight 9, and "BRIGHTNESS MAX" indicates the maximum value of brightness corresponding to the maximum value of power. The maximum value of power may be the limit value described above, and the maximum value of brightness (peak brightness) may be, for example, 2000 nit. "POWER MIN" in FIG. 3 indicates the minimum value of power supplied to the backlight 9, and "BRIGHTNESS MIN" indicates the minimum value of brightness corresponding to the minimum value of power. The minimum value of brightness may be, for example, 500 nit (brightness in normal image display), which corresponds to the brightness when a low-brightness image is displayed, and the minimum value of power may be a value corresponding to the brightness. These points are the same in FIGS. 5, 8, and 9.

[0042] In the state indicated by reference numeral 1001(i) in FIG. 3, the backlight drive control unit 8 determines whether a first predetermined time has elapsed since it began to continuously receive LED data indicating that the brightness of a predetermined number of LEDs is equal to or greater than a first predetermined value (S2 in FIG. 2). The example in FIG. 3 shows a state in which the brightness (power supplied to the backlight 9) of a predetermined number of LEDs indicated in the LED data is at its maximum value. However, as long as the brightness of the LEDs is equal to or greater than the first predetermined value, the brightness (power) may be less than the maximum value. This also applies to FIGS. 5, 8, and 9.

[0043] When the backlight drive control unit 8 determines that the first predetermined time has elapsed (YES in S2 in FIG. 2), it reduces the upper limit of power at a first speed (S3 in FIG. 2), as shown by (ii) of the reference numeral 1001. Because the backlight drive control unit 8 performs power limiter control, it also reduces the power supplied to the backlight 9 in accordance with the reduction in the upper limit of power. If this power decreases suddenly, the display brightness of a high-brightness image also decreases suddenly. If the display brightness of a high-brightness image decreases suddenly, the viewer may perceive that the image quality (display quality) of the high-brightness image has decreased suddenly. Therefore, the first speed may be set to reduce the possibility of a sudden decrease in the image quality of a high-brightness image.

[0044] Furthermore, the backlight drive control unit 8 relatively reduces the power supplied to the entire backlight 9 in accordance with the reduction in the upper limit of power. Therefore, the display brightness of the image can be reduced overall in accordance with the reduction in the upper limit of power. By reducing the power (brightness) other than the upper limit as well, the sense of contrast across the entire image is unified, and the possibility of a reduction in the display quality of the image can be reduced.

[0045] As shown in Figure 3, when a high-brightness image is displayed, the temperature of the backlight 9 and its peripheral circuits is more likely to rise than when a low-brightness image is displayed. The allowable temperature range is predetermined, and the backlight 9 and other components cannot be used at temperatures outside the allowable range. For example, if the temperature exceeds the allowable upper limit, the backlight 9 or its peripheral circuits may malfunction or stop functioning properly. When a high-brightness image is displayed continuously for a certain period of time, the backlight drive control unit 8 executes the process of S3 to reduce the power supplied to the backlight 9 in line with the reduction in the upper limit of power, thereby reducing the temperature.

[0046] However, if the power is decreased slowly, the temperature also decreases slowly, so the first speed may be set to effectively decrease the temperature while reducing the possibility of a sudden deterioration in the quality of a high-brightness image.

[0047] The first predetermined time may be set in consideration of the temperature rise. The first predetermined value, second predetermined value, predetermined number, LEDs to be subjected to brightness determination, and threshold value may also be set in consideration of the temperature rise. The various values ​​may be set so that the temperature of the backlight 9 does not exceed, for example, a temperature range Δt=55°C.

[0048] In the example of Fig. 3, as indicated by (iii) of the reference numeral 1001, the backlight drive control unit 8 reduces the upper limit of power to the minimum at a first speed. In the state indicated by (iii) of the reference numeral 1001, the backlight drive control unit 8 waits for reception of LED data indicating that the brightness of a predetermined number of LEDs is less than a second predetermined value (S5 of Fig. 2). In other words, the backlight drive control unit 8 maintains the upper limit of power at the minimum until it receives the LED data.

[0049] As shown by (iv) of 1001, when the backlight drive control unit 8 receives the LED data (YES in S5 of FIG. 2), it increases the upper limit of power at a second speed that is faster than the first speed (S7 of FIG. 2). That is, the backlight drive control unit 8 increases the upper limit of power by making the absolute value of the increase in the amount of power per unit time (absolute value of the slope) greater than the absolute value of the decrease in the amount of power per unit time (absolute value of the slope). As shown by (v) of 1001, the backlight drive control unit 8 increases the upper limit of power to a preset maximum value (YES in S8 of FIG. 2).

[0050] Fig. 4 is a graph showing an example of the amount of increase in brightness per unit time corresponding to the second speed. As shown in Fig. 4, the second speed may be set, for example, so that the brightness changes by about 1% (e.g., 20 nits) per 0.1 second. The second speed may be set, for example, so that the brightness changes by about 0.25 to 1% (e.g., 5 to 20 nits) per 0.1 second. On the other hand, the first speed may be set, for example, so that the brightness changes by about 0.1% (e.g., 2 nits) per 0.1 second.

[0051] In this way, when the backlight drive control unit 8 receives LED data indicating that the brightness of a predetermined number of LEDs is less than the second predetermined value, it increases the upper limit of power at a second speed that is greater than the first speed in (iv) of reference numeral 1001. Therefore, even if the display switches from a low-brightness image to a high-brightness image while the upper limit of power is increasing, the power supplied to the backlight 9 can be increased to the upper limit more quickly than when the upper limit of power was decreased. This reduces the possibility that a viewer will notice a change in the display brightness of the image, thereby reducing the possibility that the display quality of the image will deteriorate.

[0052] Fig. 5 is a graph showing an example of the transition of the power (LED brightness) supplied to the backlight 9 and the transition of the upper limit of the power. Fig. 5 is a graph showing an example of the transition when a high-brightness image is displayed after a low-brightness image is displayed in the state of Fig. 3.

[0053] As shown in (v) of FIG. 5, it is assumed that the backlight drive control unit 8 receives LED data again indicating that the brightness of a predetermined number of LEDs is equal to or greater than the first predetermined value when a low-brightness image is displayed. In this case, the upper limit of power is restored to its original state (after being restored to the maximum value in the example of FIG. 5), and then the display is switched as described above. Therefore, as shown in (v) of FIG. 5, the backlight drive control unit 8 can immediately increase the power to the maximum value and supply it to the backlight 9. Therefore, in this case as well, it is possible to reduce the possibility that a viewer will perceive a change in the display brightness of the image, thereby reducing the possibility of a deterioration in the display quality of the image. Furthermore, by increasing the upper limit of power at the second speed, it is possible to increase the possibility that the display is switched as described above after the upper limit of power is restored to its original state.

[0054] As described above, the control device 50 can extend the time for which a high-brightness image is displayed so as to maximize the brightness of the image (i.e., at the original display brightness when the image is displayed or at a brightness close to that display brightness) through the control of the backlight drive control unit 8. This reduces the time for which the image quality of a high-brightness image deteriorates.

[0055] In the state shown in (v) of Fig. 5, the backlight drive control unit 8 determines whether the state in which the brightness of a predetermined number of LEDs indicated in the LED data is equal to or greater than a first predetermined value has continued for a first predetermined time (S2 of Fig. 2). The first predetermined time may be set to a time different from the first predetermined time in the state shown in (i) of Fig. 5 (i.e., (i) of reference numeral 1001 in Fig. 3). When the backlight drive control unit 8 determines that the first predetermined time has passed (YES in S2 of Fig. 2), it again reduces the upper limit of power at the first speed, as shown in (vi) of Fig. 5 (S3 of Fig. 2).

[0056] In addition, in the example of reference numeral 1001 in FIG. 3 and FIG. 5, the backlight drive control unit 8 increases the upper limit of power after receiving LED data indicating that the brightness of a predetermined number of LEDs is less than a second predetermined value.

[0057] When the backlight drive control unit 8 receives the LED data, it supplies power to the backlight 9 based on the LED data. Therefore, even if the upper limit of power is increased, the power supplied to the backlight 9 is maintained at a level lower than the upper limit. Therefore, while a low-brightness image is being displayed, even if the upper limit of power is increased at a second speed higher than the first speed, the viewer will not perceive a change in display brightness. In the example of (iv) and (v) in FIG. 3 and FIG. 5, the power supplied to the backlight 9 is maintained at a level lower than the preset minimum value.

[0058] Furthermore, in the example of reference numeral 1001 in Fig. 3 and Fig. 5, when switching to supplying power lower than the minimum value (when switching to displaying a low-brightness image having brightness corresponding to the minimum value), the backlight drive control unit 8 increases the upper limit of power at the second speed. This reduces the possibility that high power will be supplied to the backlight 9 again while the supply of power is not below the minimum value and the temperature of the backlight 9 and its peripheral circuits has not yet sufficiently decreased. This makes it possible to extend the life of the backlight 9.

[0059] The temperature when a low-brightness image is displayed is within a certain range relative to the upper limit of allowable temperature. This temperature is within a certain range, particularly when the power supply is switched to a level lower than the minimum. Therefore, even if the power supplied to the backlight 9 is immediately increased to the upper limit when a low-brightness image is displayed, the temperature will not immediately exceed the upper limit of allowable temperature. Therefore, the temperature can be increased more quickly than when the upper limit of power is lowered.

[0060] Here, as shown by reference numeral 1002 in FIG. 3 , the backlight drive control unit of the comparative example can also reduce the temperature during display of a high-brightness image by lowering the upper limit of power. However, the backlight drive control unit of the comparative example increases the upper limit of power at a rate similar to the first speed. Therefore, it takes time to restore the upper limit of power to its original state. If a high-brightness image is displayed while the upper limit of power is being increased, the time for which the high-brightness image is displayed at a lower display brightness (output darker) than its original display brightness increases. The likelihood of such display also increases. By increasing the upper limit of power at a second speed greater than the first speed, as in the backlight drive control unit 8 of the present embodiment, this time can be shortened. Furthermore, the likelihood of a high-brightness image being displayed at a lower display brightness than its original display brightness can be reduced.

[0061] [Embodiment 2] Other embodiments of the present disclosure will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated. The same applies to the following embodiments.

[0062] In the first embodiment, the backlight drive control unit 8 increases the upper limit of power at the second speed after receiving LED data indicating that the brightness of a predetermined number of LEDs is less than a second predetermined value. In the second embodiment, the backlight drive control unit 8 increases the upper limit of power after a predetermined time has elapsed, regardless of receiving this LED data.

[0063] 6 is a flowchart showing another example of control by the backlight drive control unit 8. The processing described with reference to FIG. 2 will not be described here.

[0064] 6, the backlight drive control unit 8 determines whether a second predetermined time has elapsed since the start of control to reduce the upper limit of power at a first speed (after the start of processing in S3) (S11). If the backlight drive control unit 8 determines that the second predetermined time has elapsed (YES in S11), it increases the upper limit of power at the second speed (S7). The backlight drive control unit 8 continues the processing in S3 and S11 until the second predetermined time has elapsed (NO in S11).

[0065] The second predetermined time can be set arbitrarily. For example, the second predetermined time may be set so that, even if the upper limit of power is increased at the second speed and power is supplied to the backlight 9 at that upper limit, it takes a certain amount of time for the temperature to rise to the allowable upper limit. If the temperature decrease amount accompanying the reduction in the upper limit of power is too small, the temperature will quickly approach the allowable upper limit due to the power supply, so the second predetermined time may be set taking this into consideration.

[0066] If the upper limit of power is reduced to the minimum value before the second predetermined time has elapsed, the backlight drive control unit 8 can supply power to the backlight 9 at the upper limit after sufficiently reducing the temperature. On the other hand, even if the second predetermined time has elapsed before the upper limit of power is reduced to the minimum value, the backlight drive control unit 8 can supply power to the backlight 9 at the upper limit after reducing the temperature to a certain extent.

[0067] Therefore, even when the upper limit of power is increased at the second speed after the second predetermined time has elapsed since the start of the control to decrease the upper limit of power, it is possible to reduce the possibility that high power will be supplied to the backlight 9 again before the temperature of the backlight 9 and its peripheral circuits has sufficiently decreased. This makes it possible to extend the life of the backlight 9.

[0068] Also in this embodiment, the backlight drive control unit 8 increases the upper limit of power at the second speed, thereby reducing the possibility that a change in the display luminance of the image is visible. Even when the display switches from a high-luminance image to a low-luminance image and then switches back to a high-luminance image, the possibility that a change in the display luminance of the image is visible can be reduced.

[0069] In this way, even with the control of the backlight drive control unit 8 of this embodiment, the control device 50 can extend the time for which a high-brightness image is displayed so as to maximize the brightness of the image, thereby reducing the time for which the image quality of the high-brightness image deteriorates.

[0070] [Embodiment 3] In the third embodiment, the control of the backlight drive control unit 8 in the case where LED data indicating that the luminance of a predetermined number of LEDs is equal to or greater than the first predetermined value continues to be received even after the first predetermined time has elapsed will be described.

[0071] In this embodiment, if the backlight drive control unit 8 continues to receive LED data indicating brightness equal to or greater than the first predetermined value after the first predetermined time has elapsed, the backlight drive control unit 8 increases the upper limit of power at a second rate after the second predetermined time has elapsed. Specifically, if the backlight drive control unit 8 continues to receive LED data indicating that the brightness of a predetermined number of LEDs is equal to or greater than the first predetermined value after the first predetermined time has elapsed, the backlight drive control unit 8 increases the upper limit of power at the second rate after the second predetermined time has elapsed.

[0072] The upper limit of power can be set between a preset maximum value and a preset minimum value. In this embodiment, as shown in FIG. 8, which will be described later, a first threshold is set between the preset maximum value and the preset minimum value. In this embodiment, a second threshold smaller than the first threshold is set between the preset maximum value and the preset minimum value. The first threshold and the second threshold can be set arbitrarily.

[0073] <Power upper limit control> 7 is a flowchart showing another example of control by the backlight drive control unit 8. The processing described with reference to FIG. 2 will not be described here.

[0074] 7, after a first predetermined time has elapsed (if YES in S2), the backlight drive control unit 8 reduces the upper limit of power to the second threshold at a first speed (S21). After starting the control to reduce the upper limit of power (after starting the process of S21), the backlight drive control unit 8 continues to determine whether the brightness of a predetermined number of LEDs indicated in the LED data is equal to or greater than a first predetermined value (S22).

[0075] In a state where the backlight drive control unit 8 determines that the brightness of a predetermined number of LEDs indicated in the LED data is equal to or greater than the first predetermined value (YES in S22), the backlight drive control unit 8 determines whether a third predetermined time has elapsed since the upper power limit was reduced to the second threshold (S23). In the above state, if the backlight drive control unit 8 determines that the upper power limit has been reduced to the second threshold, the backlight drive control unit 8 starts counting the third predetermined time. The determination that the third predetermined time has elapsed is an example of a determination that a second predetermined time has elapsed since the control to reduce the upper power limit was started.

[0076] When the backlight drive control unit 8 determines that the third predetermined time has elapsed (YES in S23), it increases the upper limit of power at the second speed to the first threshold (S24). That is, when the upper limit of power has been reduced to below the first threshold, the backlight drive control unit 8 increases the upper limit of power at the second speed to the first threshold.

[0077] After starting the control to increase the upper limit of power (after starting the process of S24), the backlight drive control unit 8 continues to determine whether the brightness of the predetermined number of LEDs indicated in the LED data is equal to or greater than the first predetermined value (S25). In a state in which it has determined that the brightness of the predetermined number of LEDs indicated in the LED data is equal to or greater than the first predetermined value (YES in S25), the backlight drive control unit 8 determines whether a fourth predetermined time has elapsed since the upper limit of power was increased to the first threshold (S26). In the above state, if it determines that the upper limit of power has increased to the first threshold, the backlight drive control unit 8 starts counting the fourth predetermined time.

[0078] When the backlight drive control unit 8 determines that the fourth predetermined time has elapsed (YES in S26), it performs the process of S21 again. In this manner, while a high-brightness image is continuously displayed, the backlight drive control unit 8 repeatedly performs control to reduce the upper limit of power to the second threshold at the first speed and control to increase the upper limit of power to the first threshold at the second speed.

[0079] The backlight drive control unit 8 continues the processes of S22 and S23 until it determines in S23 that the third predetermined time has elapsed (if NO in S23). Also, the backlight drive control unit 8 continues the processes of S25 and S26 until it determines in S26 that the fourth predetermined time has elapsed (if NO in S26).

[0080] However, in S22 and S25, if the backlight drive control unit 8 determines that the brightness of the predetermined number of LEDs indicated in the LED data is less than the first predetermined value (NO in S22, NO in S25), it ends this process. For example, this process ends when reception of a video signal indicating a high-brightness image to the control device 50 has finished, or when a video signal indicating a low-brightness image has been received. When receiving a video signal indicating a low-brightness image, the backlight drive control unit 8 supplies power corresponding to the brightness of the low-brightness image to the backlight 9. Furthermore, when ending this process, the backlight drive control unit 8 may return the upper limit value of power to its original state (the maximum value in this embodiment).

[0081] Here, the backlight drive control unit 8 may count the third predetermined time and the fourth predetermined time as follows.

[0082] The backlight drive control unit 8 detects the power (LED_DUTY) of each driven LED and compares the power with a first threshold and a second threshold. If the backlight drive control unit 8 determines that the power is equal to or greater than the first threshold, it increments the cumulative number of determinations by "1." If the backlight drive control unit 8 determines that the power is equal to or less than the second threshold, it decrements the cumulative number of determinations by "1." Each time the backlight drive control unit 8 detects the power, it counts the cumulative number for each LED.

[0083] When the backlight drive control unit 8 determines that the cumulative number of times has reached a preset upper limit for, for example, one of the LEDs, the backlight drive control unit 8 reduces the upper limit of power from the first threshold to the second threshold. Also, when the cumulative number of times has reached a preset lower limit for, for example, all of the LEDs, the backlight drive control unit 8 increases the upper limit of power from the second threshold to the first threshold.

[0084] If the power of the first threshold value continues to be supplied to the backlight 9, the cumulative number continues to increase. Then, the power of the first threshold value continues to be supplied to the backlight 9 until the cumulative number reaches the upper limit. Therefore, the time during which the cumulative number increases until it reaches the upper limit is counted as the fourth predetermined time.

[0085] On the other hand, if the power of the second threshold value continues to be supplied to the backlight 9, the cumulative number continues to decrease. Then, the power of the second threshold value continues to be supplied to the backlight 9 until the cumulative number reaches the lower limit. Therefore, the time during which the cumulative number decreases until it reaches the lower limit is counted as the third predetermined time.

[0086] The third predetermined time and the fourth predetermined time may be set to the same time or may be set to different times. When the third predetermined time and the fourth predetermined time are counted by the cumulative number of times, the third predetermined time and the fourth predetermined time are set to the same time or different times depending on whether the increment value and the decrement value are the same.

[0087] <Control of power and its upper limit> Fig. 8 is a graph showing an example of the transition of the upper limit value of the power (LED brightness) supplied to the backlight 9. Reference numeral 1011 in Fig. 8 is a graph showing the two transitions under the control of the backlight drive control unit 8, and reference numeral 1012 is a graph showing the two transitions under separate control of the backlight drive control unit 8. Fig. 8 also shows the transition of the temperature of the LED.

[0088] In the state shown by (3i) of symbol 1011 in Figure 8, the backlight drive control unit 8 determines whether a first predetermined time has elapsed since it started to continuously receive LED data indicating that the brightness of a predetermined number of LEDs is equal to or greater than a first predetermined value (S2 in Figure 7).

[0089] When the backlight drive control unit 8 determines that the first predetermined time has elapsed (YES in S2 in FIG. 7), it reduces the upper limit of power to the second threshold at a first speed (S21 in FIG. 7), as shown by (3ii) and (3iii) of the reference numerals 1011. The backlight drive control unit 8 also reduces the power supplied to the backlight 9 in accordance with the reduction in the upper limit of power.

[0090] In the state indicated by the reference numeral 1011 (3iii), the backlight drive control unit 8 continues to receive the LED data and determines whether a third predetermined time has elapsed since the upper limit of power was reduced to the second threshold (S22, S23 in FIG. 7). The backlight drive control unit 8 maintains the upper limit of power at the second threshold until the third predetermined time has elapsed.

[0091] When the backlight drive control unit 8 determines that the third predetermined time has elapsed (YES in S23 in FIG. 7), it increases the upper limit of power at a second speed to the first threshold value (S24 in FIG. 7), as indicated by reference numeral 1011 (3iv). The backlight drive control unit 8 also increases the power supplied to the backlight 9 in accordance with the increase in the upper limit of power.

[0092] In the state indicated by (3v) of the reference numeral 1011, the backlight drive control unit 8 continues to receive the LED data and determines whether a fourth predetermined time has elapsed since the upper limit of power was increased to the first threshold (S25, S26 in FIG. 7). The backlight drive control unit 8 maintains the upper limit of power at the first threshold until the fourth predetermined time has elapsed.

[0093] When the backlight drive control unit 8 determines that the fourth predetermined time has elapsed (YES in S26 in FIG. 7), it again reduces the upper power limit to the second threshold at the first speed (S21 in FIG. 7), as indicated by (3vi) of reference numeral 1011. The backlight drive control unit 8 also reduces the power supplied to the backlight 9 in accordance with the reduction in the upper power limit.

[0094] While continuing to receive the LED data, the backlight drive control unit 8 repeatedly performs control to lower the upper power limit to the second threshold at a first speed and control to raise the upper power limit to the first threshold at a second speed. The backlight drive control unit 8 also changes the power supplied to the backlight 9 in accordance with the upper power limit. That is, the backlight drive control unit 8 supplies the backlight 9 with power that indicates the changing upper power limit.

[0095] Now, consider a case where the backlight drive control unit 8 continues to receive the LED data even after the first predetermined time has elapsed, and then receives LED data indicating that the brightness of a predetermined number of LEDs is less than a second predetermined value. That is, consider a case where the backlight drive control unit 8 continues to receive LED data indicating a high-brightness image even after the period (3i) of reference numeral 1011 has elapsed, and then receives LED data indicating a low-brightness image. In this case, as in the first embodiment, the backlight drive control unit 8 increases (restores) the upper limit value of power to the maximum value at the second speed at the timing to switch the power supply based on the LED data indicating a low-brightness image (the timing to switch to displaying a low-brightness image).

[0096] The second speed at which the power is increased to the first threshold when LED data showing a high-brightness image is continuously received and the second speed at which the power is increased to the maximum value when power supply is switched based on LED data showing a low-brightness image are switched are set to the same value, but these two second speeds may be set to different values.

[0097] <Power control taking backlight temperature into account> As described above, when LED data showing a high-brightness image is continuously received (when a high-brightness image is continuously displayed), the backlight drive control unit 8 increases the upper limit of power from the second threshold to the first threshold at the second speed. On the other hand, as indicated by reference numeral 1012 in Fig. 8, when a high-brightness image is continuously displayed, the backlight drive control unit 8 can also increase the upper limit of power from the second threshold to the maximum value at the second speed.

[0098] However, when a high-brightness image is continuously displayed, the power supplied to the backlight 9 also changes in accordance with the change in the upper limit of power. Therefore, as shown in Fig. 8, when the upper limit of power is increased to the maximum value (see reference numeral 1012), the rate of increase in the temperature of the backlight 9 and its peripheral circuits (hereinafter simply referred to as temperature) is greater than when the upper limit of power is increased to the first threshold value (see reference numeral 1011). Furthermore, when the upper limit of power is increased to the maximum value, the temperature itself becomes higher than when the upper limit of power is increased to the first threshold value (see reference numerals 1011 (3v) and 1012 (3xii) and 1012 (3xiiii) in Fig. 8).

[0099] Furthermore, temperature decreases more slowly than it increases. Therefore, the higher the temperature rises, the more likely it is that lowering the upper power limit will cause the temperature to rise again before it has sufficiently decreased. Therefore, repeatedly increasing the upper power limit will also cause the temperature to rise gradually.

[0100] In the case of reference numeral 1011, as shown in (3v) and (3viii), the temperature rise associated with the second increase in the upper limit of power is almost the same as the temperature rise associated with the first increase in the upper limit of power. Therefore, even if the upper limit of power is repeatedly increased to the first threshold, the temperature rise remains almost constant or only slightly higher. On the other hand, in the case of reference numeral 1012, as shown in (3xii) and (3xiiii), the temperature rise associated with the second increase in the upper limit of power is higher than the temperature rise associated with the first increase in the upper limit of power. Therefore, when the upper limit of power is repeatedly increased to the maximum value, the temperature rise gradually increases.

[0101] The allowable temperature range is determined in advance, and the backlight 9 and other components cannot be used beyond this allowable range (allowable upper limit), and so it is necessary to operate the backlight 9 and other components within the allowable temperature range. As described above, the backlight drive control unit 8 only increases the upper limit of power up to the first threshold (does not return it to the maximum value), so even if the power required to display a high-brightness image increases by increasing the upper limit of power, the possibility of the temperature increasing significantly can be reduced.

[0102] Furthermore, because the backlight drive control unit 8 increases the upper limit of power at a second speed higher than the first speed, the time for displaying a high-brightness image can be extended while maintaining the display brightness as close to the original brightness as possible. Furthermore, even if the backlight drive control unit 8 repeatedly increases the upper limit of power, the possibility of a gradual increase in temperature can be reduced. Therefore, the control device 50 can display a high-brightness image for as long as possible while maintaining the display brightness as close to the original brightness as possible within the temperature tolerance range.

[0103] Furthermore, the backlight drive control unit 8 repeatedly performs control to lower the upper power limit to the second threshold and control to raise the upper power limit to the first threshold. By raising the upper power limit only to the first threshold, the possibility of the temperature of the backlight 9 gradually increasing can be reduced, as described above. Furthermore, by lowering the upper power limit only to the second threshold, the control device 50 can display a high-brightness image at a brightness closer to the original display brightness than when the upper power limit is lowered below the second threshold. Therefore, the control device 50 can display a high-brightness image for as long as possible while limiting the degree of degradation in image quality.

[0104] <Modification of upper limit control of power> As described above, from the viewpoint of temperature, it is preferable that the backlight drive control unit 8 repeatedly performs control to lower the upper limit of power to the second threshold and control to raise the upper limit of power to the first threshold. However, as long as it is possible to operate the backlight 9 and the like within the allowable temperature range, the control of the upper limit of power is not limited to this. For example, it is possible to operate the backlight 9 and the like within the allowable temperature range by setting the third predetermined time to a relatively long period or by reducing the possibility of a gradual increase in temperature by a method other than power control.

[0105] For example, as indicated by reference numeral 1012 in Fig. 8, the backlight drive control unit 8 may repeatedly perform control to lower the upper limit of power to the second threshold and control to raise the upper limit of power to the maximum value. In other words, the backlight drive control unit 8 may raise the upper limit of power to the maximum value instead of the first threshold value.

[0106] Even when controlling in this manner, by lowering the upper limit of power to the second threshold, the power for displaying a high-brightness image can also be reduced. This allows the temperature of the backlight 9 to be reduced. Furthermore, once the temperature has dropped to a certain level, the upper limit of power can be increased to its maximum value, allowing the power for displaying a high-brightness image to be increased to its maximum value. This reduces the possibility of a temperature rise, while ensuring the time for displaying a high-brightness image at its original display brightness.

[0107] 9, the backlight drive control unit 8 may repeatedly perform control to lower the upper limit of power to the minimum value and control to raise the upper limit of power to the maximum value. In other words, the backlight drive control unit 8 may lower the upper limit of power to the minimum value instead of the second threshold value. FIG. 9 is a graph showing another example of the transition of the upper limit of power (LED brightness) supplied to the backlight 9. The example in FIG. 9 corresponds to the control when LED data showing a high brightness image is continuously received in the second embodiment.

[0108] Even when controlling in this manner, by lowering the upper limit of power to the minimum value, the power for displaying a high-brightness image can be further reduced compared to when the upper limit of power is lowered to the second threshold value. This allows the temperature to be further reduced. Also, as described above, the power for displaying a high-brightness image can be increased to the maximum value. This allows the high-brightness image to be displayed at its original display brightness while further reducing the possibility of a temperature rise.

[0109] [Software implementation example] The functions of the control device 50 (hereinafter referred to as the "device") can be realized by a program that causes a computer to function as the device, and a program that causes a computer to function as each control block of the device (particularly each part included in the control device 50).

[0110] 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, thereby realizing the functions described in each of the above embodiments.

[0111] The program may be non-transitory and may be recorded on 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 supplied to the device via any wired or wireless transmission medium.

[0112] 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 disclosure. In addition, the functions of each of the control blocks can be realized by, for example, a quantum computer.

[0113] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may run on the control device or on another device (for example, an edge computer or a cloud server).

[0114] 〔summary〕 A control device according to aspect 1 of the present disclosure is a control device that controls a backlight, and includes a control unit that, when the supply of power to the backlight is maintained for a first predetermined time so that the image has a brightness equal to or greater than a first predetermined value, reduces the upper limit value of the power at a first speed and then increases it at a second speed greater than the first speed, in accordance with brightness information of the image.

[0115] According to the above configuration, the time for which a high-brightness image is displayed can be extended so as to maximize the brightness of the image (i.e., at the original display brightness when the image is displayed or at a brightness close to the original display brightness), thereby reducing the time for which the image quality of the high-brightness image deteriorates.

[0116] In the control device of aspect 2 of the present disclosure, in aspect 1, the control unit starts control to lower the upper limit value at the first speed, and then increases the upper limit value at the second speed when switching the power supply so that the image has a brightness less than a second predetermined value according to brightness information of the image.

[0117] According to the above configuration, it is possible to reduce the possibility that a change in display luminance is visible when switching from a low-luminance image to a high-luminance image, thereby reducing the possibility that the display quality of the image will be reduced.

[0118] In the control device of aspect 3 of the present disclosure, in aspect 2, the control unit is capable of lowering the upper limit value to a predetermined minimum value, and when switching to a power supply lower than the minimum value as the power supply switching control, the control unit increases the upper limit value at the second speed.

[0119] According to the above configuration, it is possible to reduce the possibility of high power being supplied to the backlight again while the power supply is not below the minimum value and the temperature of the backlight and surrounding circuits has not yet sufficiently decreased, thereby extending the life of the backlight.

[0120] In a control device according to aspect 4 of the present disclosure, in any one of aspects 1 to 3, the control unit increases the upper limit value at the second speed after a second predetermined time has elapsed since starting control to lower the upper limit value at the first speed.

[0121] The above configuration reduces the possibility that a change in the display brightness of an image is visible, thereby reducing the possibility that the display quality of the image will be reduced. It also reduces the possibility that high power will be supplied to the backlight again before the temperature of the backlight and its peripheral circuits has sufficiently decreased, thereby extending the life of the backlight.

[0122] In the control device of aspect 5 of the present disclosure, in aspect 4, if the control unit continues to receive brightness information of the image indicating a brightness greater than or equal to the first predetermined value after the first predetermined time has elapsed, the control unit increases the upper limit value at the second speed after the second predetermined time has elapsed.

[0123] According to the above configuration, by increasing the upper limit value at a second speed that is greater than the first speed, it is possible to display a high-brightness image for a longer period of time at a brightness close to the original brightness when the high-brightness image is displayed, thereby reducing the possibility of a decrease in the display quality of the high-brightness image.

[0124] In the control device of aspect 6 of the present disclosure, in aspect 5, the upper limit value can be set between a predetermined maximum value and a predetermined minimum value, a first threshold value is set in advance between the maximum value and the minimum value, and when the control unit lowers the upper limit value to be less than the first threshold value, the control unit raises the upper limit value to the first threshold value at the second speed.

[0125] According to the above configuration, by increasing the upper limit value at a second speed that is higher than the first speed, even if the power required to display a high brightness image increases, the possibility of the temperature of the backlight and peripheral circuits increasing significantly can be reduced.

[0126] In the control device of aspect 7 of the present disclosure, in aspect 6, a second threshold value smaller than the first threshold value is pre-set between the maximum value and the minimum value, and the control device repeatedly performs control to lower the upper limit value to the second threshold value and control to raise the upper limit value to the first threshold value.

[0127] According to the above configuration, it is possible to limit the degree of degradation in the quality of high-brightness images while reducing the possibility of an increase in the temperature of the backlight and peripheral circuits.

[0128] In the control device of aspect 8 of the present disclosure, in aspect 5, the upper limit value can be set between a predetermined maximum value and a predetermined minimum value, and a first threshold value and a second threshold value smaller than the first threshold value are set in advance between the maximum value and the minimum value, and control to lower the upper limit value to the second threshold value and control to raise the upper limit value to the maximum value are repeatedly performed.

[0129] According to the above configuration, by lowering the upper limit, the power required for displaying a high-brightness image can also be reduced. This allows the temperature of the backlight and peripheral circuits to be reduced. Furthermore, once the temperatures of the backlight and peripheral circuits have dropped to a certain level, the upper limit can be increased to its maximum value, allowing the power required for displaying a high-brightness image to be increased to its maximum value. This allows the high-brightness image to be displayed at its original display brightness. This reduces the possibility of the backlight temperature increasing, while ensuring the time required for displaying a high-brightness image at its original display brightness.

[0130] The control device according to aspect 9 of the present disclosure is, in aspect 5, a control device that repeatedly performs control to lower the upper limit value to a preset minimum value and control to raise the upper limit value to a preset maximum value.

[0131] According to the above configuration, by lowering the upper limit value to the minimum value, the power required for displaying a high-brightness image can be further reduced. This allows the temperature of the backlight and peripheral circuits to be further reduced. Furthermore, once the temperatures of the backlight and peripheral circuits have dropped to a certain level, the upper limit value can be raised to the maximum value, allowing the power required for displaying a high-brightness image to be raised to the maximum value. This allows the high-brightness image to be displayed at its original display brightness. This ensures that the time required for displaying a high-brightness image at its original display brightness is secured while further reducing the possibility of the backlight temperature rising.

[0132] The control device according to each aspect of the present disclosure may be realized by a computer. In this case, the control program of the control device that causes the computer to operate as each part (software element) of the control device to realize the control device on the computer, and the computer-readable recording medium on which it is recorded, also fall within the scope of the present disclosure.

[0133] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of symbols]

[0134] 1 antenna 2 Tuners 3. Video Processing Section 4 Display control section 5 Area active control section 6 LCD drive unit 7 LCD panel 8 Backlight drive control unit (control unit) 9 Backlight 10 LCD display device 50 Control device

Claims

1. A control device for controlling a backlight, a control device including a control unit that, when the supply of power to the backlight is maintained for a first predetermined time so that the image has a brightness equal to or greater than a first predetermined value, reduces the upper limit value of the power at a first speed and then increases the upper limit value at a second speed greater than the first speed, in accordance with brightness information of the image.

2. 2. The control device according to claim 1, wherein the control unit, after starting control of lowering the upper limit value at the first speed, increases the upper limit value at the second speed when switching the supply of power so that the image has a brightness less than a second predetermined value according to brightness information of the image.

3. The control unit The upper limit value can be reduced to a preset minimum value, The control device according to claim 2 , wherein the control of switching the power supply is performed by increasing the upper limit value at the second speed when switching to the power supply lower than the minimum value.

4. The control device according to claim 1 , wherein the control unit increases the upper limit value at the second speed after a second predetermined time has elapsed since starting control to decrease the upper limit value at the first speed.

5. 5. The control device according to claim 4, wherein, if the control unit continues to receive brightness information of the image indicating a brightness equal to or greater than the first predetermined value after the first predetermined time has elapsed, the control unit increases the upper limit value at the second speed after the second predetermined time has elapsed.

6. The upper limit value can be set between a preset maximum value and a preset minimum value, a first threshold value is set in advance between the maximum value and the minimum value; The control device according to claim 5 , wherein the control unit, when the upper limit value has been reduced to be less than the first threshold value, increases the upper limit value to the first threshold value at the second speed.

7. a second threshold value smaller than the first threshold value is set in advance between the maximum value and the minimum value; The control device according to claim 6 , wherein control for lowering the upper limit value to the second threshold value and control for raising the upper limit value to the first threshold value are repeatedly performed.

8. The upper limit value can be set between a preset maximum value and a preset minimum value, a first threshold value and a second threshold value smaller than the first threshold value are set in advance between the maximum value and the minimum value; The control device according to claim 5 , wherein control for lowering the upper limit value to the second threshold value and control for raising the upper limit value to the maximum value are repeatedly performed.

9. The control device according to claim 5 , wherein control for lowering the upper limit value to a preset minimum value and control for raising the upper limit value to a preset maximum value are repeatedly performed.

Images