Display device, display device control method, and display control program

Abstract

To maintain as much as possible a preset luminance being a luminance set to a lighting unit, while preventing a deterioration of the lighting unit.SOLUTION: A display (1) comprises: a lighting unit (141); a detection unit (11) that detects a peripheral temperature of the lighting unit (141); a setting unit (12) that sets a preset luminance of the lighting unit (141); and a control unit (13) that, based on the peripheral temperature and the preset luminance, controls whether to maintain the luminance of the lighting unit (141) to the preset luminance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a display device, a control method for a display device, and a display control program. [Background technology]

[0002] In recent years, liquid crystal displays (LCDs) have often been used as display units in display devices. In such cases, an illumination unit such as a backlight equipped with light-emitting diodes (LEDs) is usually provided behind the LCD.

[0003] When using the above-described lighting unit, a technique has been developed to control the brightness of the lighting unit to be reduced based on the ambient temperature of the lighting unit so as to prevent the lighting unit from deteriorating.

[0004] Patent document 1 describes a display device that includes an illumination unit, a detection unit that detects the ambient temperature of the illumination unit, and a control unit that controls the illumination unit to reduce its brightness if the ambient temperature detected by the detection unit is higher than a predetermined temperature. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-219008 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the above-mentioned conventional technology, the brightness of the illumination unit is reduced as the ambient temperature rises, and the brightness of the illumination unit is maintained when the ambient temperature does not rise, which causes a problem that the brightness of the illumination unit may be maintained even when the brightness of the illumination unit is high, which may cause deterioration of the illumination unit.

[0007] Furthermore, the above-described conventional technology changes the brightness of the lighting unit based only on the ambient temperature of the lighting unit, which has the problem that the brightness of the lighting unit may be reduced even when it is not actually necessary.

[0008] An object of one aspect of the present invention is to provide a display device and a related art thereof that can maintain the set luminance, which is the luminance set in the illuminating unit, as much as possible while preventing deterioration of the illuminating unit. [Means for solving the problem]

[0009] In order to solve the above problem, a display device according to one aspect of the present invention is characterized by comprising an illumination unit, a detection unit that detects the ambient temperature of the illumination unit, a setting unit that sets the set brightness of the illumination unit, and a control unit that controls whether or not to maintain the brightness of the illumination unit at the set brightness based on the ambient temperature and the set brightness.

[0010] A control method for a display device according to one aspect of the present invention is characterized in that it includes an illumination step in which the display device illuminates using an illumination unit, a detection step in which the display device detects the ambient temperature of the illumination unit, a setting step in which the display device sets a set brightness of the illumination unit, and a control step in which the display device controls whether or not to maintain the brightness of the illumination unit at the set brightness based on the ambient temperature and the set brightness. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to realize a display device and related techniques that can maintain the set brightness, which is the brightness set in the illumination unit, as much as possible while preventing deterioration of the illumination unit. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing an example of the configuration of a display device according to a first embodiment. [Figure 2] 1 is a schematic diagram illustrating the appearance of a display device according to a first embodiment. [Figure 3]FIG. 10 is a diagram illustrating an example of a table showing the correspondence relationship between the ambient temperature, the set brightness, and the time for which the set brightness is maintained. [Figure 4] 4 is a flowchart showing an example of a control method for the display device according to the first embodiment. [Figure 5] FIG. 10 is a block diagram showing an example of the configuration of a display device according to a second embodiment. [Figure 6] FIG. 10 is a diagram illustrating an example of a table showing the correspondence between the ambient temperature and the threshold value of the set brightness. [Figure 7] FIG. 10 is a diagram illustrating an example of a graph showing the correspondence relationship between the ambient temperature and the threshold value of the set brightness. [Figure 8] 10 is a flowchart showing an example of a control method for the display device according to the second embodiment. [Figure 9] FIG. 10 is a block diagram showing an example of the configuration of a display device according to a third embodiment. [Figure 10] 10 is a flowchart showing an example of a control method for the display device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Embodiment 1> [Display device 1] The display device 1 according to the first embodiment and a method for controlling the display device 1 will be described below with reference to FIGS.

[0014] Fig. 1 is a block diagram showing an example of the configuration of a display device 1 according to embodiment 1. Fig. 2 is a schematic diagram showing the appearance of the display device 1 according to embodiment 1.

[0015] The display device 1 is a device that displays images, and is, for example, a television as shown in Fig. 2. As shown in Fig. 1, the display device 1 includes a detection unit 11, a setting unit 12, a control unit 13, and a display unit 14.

[0016] [Detection unit 11] The detector 11 detects the ambient temperature of the lighting unit 141 .

[0017] For example, the detection unit 11 may be provided inside the display device 1, near the illumination unit 141 in the display unit 14 (for example, on a board on which the illumination unit 141 is placed), and may be configured with a resistor and a thermistor connected between a power supply and ground. In this case, the detection unit 11 detects the change in the current flowing through the thermistor, which has changed due to the ambient temperature, as a change in the voltage at the node between the resistor and thermistor, and detects the ambient temperature of the illumination unit 141 by referring to a table showing the relationship between voltage and temperature.

[0018] The detection unit 11 may be configured to detect the ambient temperature at predetermined intervals, or may be configured to irregularly detect the ambient temperature of the illumination unit 141. When detecting the ambient temperature of the illumination unit 141 irregularly, the detection unit 11 may, for example, constantly acquire the ambient temperature, and when the ambient temperature exceeds a threshold, detect the ambient temperature that has exceeded the threshold.

[0019] [Settings section 12] The setting unit 12 sets the brightness setting of the illumination unit 141 .

[0020] For example, the setting unit 12 sets a desired brightness as the set brightness of the illumination unit 141 via an input unit (not shown) that accepts a user's input from an external device (not shown) such as a remote control.

[0021] The setting unit 12 may set the set luminance in accordance with the pixel value of the image signal input to the display device 1. For example, when the pixel value of the image signal is low, the setting unit 12 may set the set luminance so that the duty ratio, which is the ratio of the light emission period of the image to the display period of the image, is 50%. The setting unit 12 may also set the set luminance at a timing desired by the user.

[0022] [Control Unit 13] The control unit 13 controls whether or not the brightness of the illumination unit 141 is to be maintained at the set brightness, based on the ambient temperature detected by the detection unit 11 and the set brightness set by the setting unit 12.

[0023] In this case, for example, the control unit 13 first acquires the ambient temperature from the detection unit 11, and acquires the set brightness from the setting unit 12. Next, the control unit 13 refers to a table showing the correspondence between the set brightness and the power, and acquires the power required for the illumination unit 141 to illuminate at the set brightness acquired from the setting unit 12 at the ambient temperature acquired from the detection unit 11.

[0024] Next, based on the obtained power, the control unit 13 controls whether to maintain the luminance of the illumination unit 141 at the set luminance. If the power is high, the control unit 13 controls the luminance of the illumination unit 141 so that it is lower than the set luminance by reducing the power.

[0025] In this way, by controlling whether or not to maintain the brightness of the lighting unit 141 at the set brightness based not only on the ambient temperature but also on the set brightness, it is possible to prevent deterioration of the lighting unit 141 while maintaining the set brightness as much as possible.

[0026] (Example 1 of determination of maintenance period of set brightness by control unit 13) The control unit 13 may determine the period for which the set brightness is maintained according to the ambient temperature and the set brightness, and maintain the brightness of the illumination unit 141 at the set brightness during the maintenance period. In this case, the control unit 13 determines the period for which the set brightness is maintained, for example, by referring to a table showing the correspondence between the ambient temperature, the set brightness, and the period for which the set brightness is maintained.

[0027] An example of how the control unit 13 determines the period for which the set brightness is maintained according to the ambient temperature and the set brightness will be described below with reference to Fig. 3. Fig. 3 is a diagram showing an example of a table showing the correspondence between the ambient temperature, the set brightness, and the period for which the set brightness is maintained. The set brightness in Fig. 3 represents a duty ratio, which is the ratio of the light emission period of an image to the display period of the image.

[0028] In the example shown in FIG. 2, when the ambient temperature is 30°C or less and the set brightness is 100%, the control unit 13 determines the period for which the set brightness is maintained to be 30 seconds. When the ambient temperature is above 30°C, i.e., greater than 30°C and less than 35°C, the control unit 13 determines the period for which the set brightness is maintained to be 25 seconds. When the set brightness is above 35°C and less than 40°C, the control unit 13 determines the period for which the set brightness is maintained to be 20 seconds. When the ambient temperature is above 40°C and less than 45°C, the control unit 13 determines the period for which the set brightness is maintained to be 15 seconds. When the ambient temperature is above 45°C and less than 50°C, the control unit 13 determines the period for which the set brightness is maintained to be 10 seconds.

[0029] In this way, by determining the period for maintaining the set brightness to be shorter as the ambient temperature rises, so that the amount of heat generated by illuminating the illumination unit 141 at the set brightness does not become too high and deteriorate the illumination unit 141, the brightness of the illumination unit 141 can be preferably maintained at the set brightness. Therefore, the set brightness can be maintained as much as possible while more preferably preventing deterioration of the illumination unit 141.

[0030] 3 does not include a period for which the set brightness is maintained when the ambient temperature is above 50°C. In this way, the control unit 13 may turn off the power to the display device 1 when the ambient temperature is above 50°C. When the ambient temperature is above 50°C, the illumination unit 141 begins to deteriorate, but by turning off the power to the display device 1 when the ambient temperature is above 50°C, deterioration of the illumination unit 141 can be more effectively prevented.

[0031] (Example 2 of Determining Period for Maintaining Set Brightness by Control Unit 13) The control unit 13 may determine the maintenance period of the set brightness so that the ambient temperature of the lighting unit 141 after rising due to the amount of heat generated when the lighting unit 141 is illuminated at the set brightness during the maintenance period is equal to or lower than a predetermined temperature.

[0032] In this case, the control unit 13 calculates the amount of heat generated when the lighting unit 141 is illuminated at a set brightness for the maintenance period, for example, by multiplying the power consumed when the lighting unit 141 illuminates at a certain set brightness and ambient temperature by the maintenance period.

[0033] Next, the control unit 13 refers to a table showing the correspondence between the amount of heat and the rise in the ambient temperature, and determines the ambient temperature of the lighting unit 141 after the rise, which will occur due to the amount of heat generated when the lighting unit 141 is illuminated at the set brightness for the maintenance period.

[0034] Next, the control unit 13 determines the period for which the set brightness is to be maintained so that the ambient temperature of the lighting unit 141 after the rise is equal to or lower than a predetermined temperature, which is an allowable temperature at which the lighting unit 141 does not deteriorate, and is obtained by a known method such as an experiment.

[0035] That is, when the control unit 13 illuminates the lighting unit 141 at the set brightness, the control unit 13 calculates the maintenance period as the period until the ambient temperature of the lighting unit 141 reaches a predetermined temperature while the lighting unit 141 continues to be illuminated at the current set brightness.

[0036] In this way, by determining the maintenance period so that the amount of heat generated by illuminating the illumination unit 141 at the set brightness does not become too high and cause the illumination unit 141 to deteriorate, it is possible to more suitably prevent deterioration of the illumination unit 141 while maintaining the set brightness as much as possible.

[0037] (Example 3 of determination of maintenance period of set brightness by control unit 13) The control unit 13 may calculate the increase in ambient temperature per unit time based on the ambient temperatures of any two or more lighting units 141 detected by the detection unit 11 at a certain set brightness before the maintenance period has elapsed, and determine the maintenance period for the set brightness to be below a predetermined temperature.

[0038] Here, the detection unit 11 calculates the maximum amount of heat that the lighting unit 141 can maintain without deteriorating, and considers the time before the amount of heat generated by the lighting unit 141 reaches this maximum amount of heat to be before the maintenance period has elapsed, thereby making it possible to determine the maintenance period for the set brightness without using a table.

[0039] Even with this method, the maintenance period can be determined so that illuminating the lighting unit 141 at the set brightness does not cause the amount of heat generated to become too high, which would cause the lighting unit 141 to deteriorate, and the set brightness can be maintained as much as possible while more suitably preventing deterioration of the lighting unit 141.

[0040] [Display section 14] The display unit 14 displays an image based on an image signal input to the display device 1 via a receiving unit (not shown) that receives broadcast waves, an input unit (not shown) that accepts input from an external device (not shown), and a reading unit (not shown) that reads a recording medium.

[0041] Examples of the external device mentioned above include a remote control, a BD player, a DVD player, a personal computer, and a game device.

[0042] The display unit 14 is configured by, for example, an LCD (Liquid Crystal Display).

[0043] (Lighting Section 141) The illumination unit 141 illuminates the area of ​​the display unit 14 where an image is displayed.

[0044] The illumination unit 141 is not particularly limited as long as the amount of heat generated increases in accordance with the ambient temperature and the set brightness, but may be, for example, a backlight equipped with an LED (Light Emitting Diode).

[0045] In particular, when the illumination unit 141 includes an LED, the illumination unit 141 is likely to deteriorate if the set brightness is continuously maintained, but by controlling whether or not to maintain the brightness of the illumination unit 141 at the set brightness based on the ambient temperature and the set brightness, it is possible to suitably prevent deterioration of the illumination unit 141. That is, the display device 1 according to this embodiment can suitably apply a backlight including an LED to the illumination unit 141.

[0046] [Control method of display device 1] Next, a method for controlling the display device 1 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the method for controlling the display device 1 according to the first embodiment.

[0047] In the example shown in Figure 4, it is assumed that the setting unit 12 of the display device 1 has previously performed a setting step in which it sets the set brightness of the lighting unit 141 in the display unit 14 of the display device 1, and an illumination step in which the lighting unit 141 illuminates the area in which an image is displayed on the display unit 14.

[0048] (Step S101) The setting unit 12 of the display device 1 detects the ambient temperature of the illumination unit 141 (detection step).

[0049] (Step S102) The control unit 13 of the display device 1 acquires the set brightness and the ambient temperature detected in step S101 (acquisition step).

[0050] (Step S103) The control unit 13 of the display device 1 controls whether or not to maintain the brightness of the illumination unit 141 at the set brightness, based on the set brightness and the ambient temperature detected in step S101 (control step).

[0051] 4, if the ambient temperature is 50° C. or less (YES in step S103), the control unit 13 proceeds to step S104. If the ambient temperature is above 50° C. (NO in step S103), the control unit 13 proceeds to step S106.

[0052] (Step S104) The control unit 13 determines a period for which the set brightness is to be maintained, depending on the set brightness and the ambient temperature detected in step S103 (maintenance period determination step).

[0053] (Step S105) The control unit 13 maintains the luminance of the illumination unit 141 at the set luminance during the maintenance period (maintenance step).

[0054] After step S105 is completed, the display device 1 may re-execute each step from step S101 described above without resetting the set brightness using the setting unit 12. The display device 1 may re-execute each step from step S101 described above after resetting the set brightness using the setting unit 12 in accordance with an image input to the display device 1 or a user operation. Furthermore, after step S105 is completed, the display device 1 may end the processing of each step without executing each step.

[0055] (Step S106) The control unit 13 turns off the power supply to the display device 1 (power-off step).

[0056] <Embodiment 2> The display device of the present invention, like the display device 1X of embodiment 2, may determine a threshold value for the set brightness depending on the ambient temperature, and if the period during which the set brightness exceeds the threshold value exceeds a predetermined period, may reduce the brightness of the lighting unit 141 to the threshold value.

[0057] 5 to 8, a display device 1X according to embodiment 2 will be described below. For ease of explanation, members having the same functions as those described in the above embodiments will be denoted by the same reference numerals, and descriptions thereof will be omitted.

[0058] [Display device 1X] Fig. 5 is a block diagram showing an example of the configuration of a display device 1X. As shown in Fig. 5, the display device 1X includes a control unit 13X instead of the control unit 13 in the first embodiment. Except for this, the display device 1X according to the second embodiment has the same configuration as the display device 1 according to the first embodiment.

[0059] [Control unit 13X] The control unit 13X determines a threshold value for the set brightness in accordance with the ambient temperature, and when the period during which the set brightness exceeds the threshold value exceeds a predetermined period, reduces the brightness of the illumination unit 141 to the threshold value.

[0060] Specifically, when the period during which the set luminance acquired from the setting unit 12 exceeds the threshold exceeds a predetermined period, the control unit 13 reduces the luminance of the illumination unit 141 to the threshold by reducing the amount of current flowing through the illumination unit 141. In other words, even when the set luminance exceeds the threshold, the control unit 13 does not reduce the luminance of the illumination unit 141 if the period during which the set luminance exceeds the threshold is within the predetermined period.

[0061] This makes it possible to more suitably prevent deterioration of the illumination unit 141 and maintain the set brightness as much as possible.

[0062] The predetermined period is not particularly limited as long as the amount of heat generated when the illumination unit 141 is illuminated at a set brightness exceeding the threshold value for the predetermined period does not deteriorate the illumination unit 141. Therefore, the predetermined period may be the same as the maintenance period in the first embodiment, or may not be the same.

[0063] The threshold value is not particularly limited, but for example, when the ambient temperature is 50°C, it is preferable to gradually decrease the duty ratio of the brightness of the lighting unit 141 as the ambient temperature rises from above 30°C so that the duty ratio is between 50% and 70%.

[0064] In other words, it is preferable that the control unit 13X determines the threshold value of the set brightness so that, when the period during which the set brightness exceeds the threshold value exceeds a predetermined period, the duty ratio of the brightness of the lighting unit 141 gradually decreases from 30% to 50% as the ambient temperature rises.

[0065] By determining the threshold value in this way, it is possible to more suitably prevent deterioration of the illumination unit 141 and maintain the set brightness as much as possible.

[0066] (Example 1 of determining the threshold value of the set brightness by the control unit 13X) Hereinafter, a first example of determining the set brightness threshold value by the control unit 13X will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of a table showing the correspondence relationship between the ambient temperature and the set brightness threshold value. As in Fig. 4, the set brightness threshold value in Fig. 6 represents a duty ratio, which is the ratio of the light emission period of an image to the display period of the image.

[0067] In the example shown in FIG. 6, when the ambient temperature is 30° C. or lower, the control unit 13X determines the threshold value of the set brightness to be 100%, and does not reduce the brightness of the illumination unit 141.

[0068] When the ambient temperature is above 30°C and below 35°C, the control unit 13X determines the threshold value of the set brightness to 90%, and when the period during which the set brightness exceeds 90% exceeds a predetermined period, the control unit 13X reduces the brightness of the lighting unit 141 to 90%.

[0069] When the ambient temperature is above 35°C and below 40°C, the control unit 13X determines the threshold value of the set brightness to be 80%, and when the period during which the set brightness exceeds 80% exceeds a predetermined period, the control unit 13X reduces the brightness of the lighting unit 141 to 80%.

[0070] When the ambient temperature is above 40°C and below 45°C, the control unit 13X determines the threshold value of the set brightness to 70%, and when the period during which the set brightness exceeds 70% exceeds a predetermined period, the control unit 13X reduces the brightness of the lighting unit 141 to 70%.

[0071] When the ambient temperature is above 45°C and below 50°C, the control unit 13X determines the threshold value of the set brightness to 60%, and when the period during which the set brightness exceeds 60% exceeds a predetermined period, the control unit 13X reduces the brightness of the lighting unit 141 to 60%.

[0072] (Example 2 of determining the threshold value of the set brightness by the control unit 13X) In the example shown in FIG. 6, the control unit 13X determines the threshold value of the set brightness by referring to a table in which the ambient temperature and the set brightness have a step function relationship. However, in this embodiment, the threshold value of the set brightness may be determined by referring to a graph in which the ambient temperature and the set brightness have a linear relationship.

[0073] Hereinafter, a second example of determining the set brightness threshold value by the control unit 13X will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of a graph showing the correspondence relationship between the ambient temperature and the set brightness threshold value. The horizontal axis of Fig. 7 represents the ambient temperature, and the vertical axis represents the set brightness threshold value, which is the duty ratio, which is the ratio of the light emission period of an image to the display period of the image.

[0074] In the example shown in FIG. 7, when the ambient temperature is 30° C. or lower, the control unit 13X determines the threshold value of the set brightness to be 100%, and does not reduce the brightness of the illumination unit 141.

[0075] As shown in Fig. 7, when the ambient temperature is above 30°C, the control unit 13X determines the threshold value of the set brightness D1, indicated by the dotted line in Fig. 7, to a value corresponding to the ambient temperature shown in Fig. 7. In this way, when the ambient temperature is above 30°C, by determining the threshold value of the set brightness to a set brightness that has a linear relationship with the ambient temperature, it is possible to determine the threshold value of the set brightness so that the set brightness is more appropriate according to the ambient temperature.

[0076] This makes it possible to more suitably prevent deterioration of the illumination unit 141 and maintain the set brightness as much as possible.

[0077] (Example of reduction in brightness of illumination unit 141 by control unit 13X) Hereinafter, an example of reducing the luminance of the illumination unit 141 by the control unit 13X when the ambient temperature is 40° C. will be described with reference to FIG.

[0078] As shown in FIG. 6, when the ambient temperature is 40° C., the control unit 13X determines the threshold value of the set brightness to be 80%.

[0079] When the ambient temperature is 40° C. and the period during which the set brightness is 100% exceeds a predetermined period, the control unit 13X reduces the brightness of the illumination unit 141 to 80%.

[0080] If the ambient temperature is 40° C. and the period during which the set brightness is 100% does not exceed a predetermined period, the control unit 13X maintains the brightness of the illumination unit 141 at 100%.

[0081] In addition, when the ambient temperature is 40°C and the period during which the set brightness is 70% exceeds a predetermined period, the control unit 13X maintains the brightness of the lighting unit 141 at 70% because the set brightness does not exceed the threshold value of 80%.

[0082] In this way, the control unit 13X reduces the luminance of the illumination unit 141 to the threshold value only when the set luminance exceeds the threshold value and the period during which the set luminance exceeds the threshold value exceeds a predetermined period, and therefore reduces the luminance of the illumination unit 141 to the threshold value only when necessary. This makes it possible to more effectively prevent deterioration of the illumination unit 141 while maintaining the set luminance as favorably as possible.

[0083] [Control method of display device 1X] Next, a control method for the display device 1X according to embodiment 2 will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the control method for the display device 1X according to embodiment 2. Steps S201, S202, and S209 in Fig. 8 are the same as steps S101, S102, and S106 in Fig. 4, and therefore will not be described here.

[0084] In the example shown in Figure 8, it is assumed that the setting unit 12 of the display device 1X has previously performed a setting process in which it sets the set brightness of the lighting unit 141 in the display unit 14 of the display device 1X, and an illumination process in which the lighting unit 141 illuminates the area in the display unit 14 where an image is displayed.

[0085] (Step S203) If the ambient temperature is greater than 30°C and less than or equal to 50°C (YES in step S203), the control unit 13X proceeds to step S204. If the ambient temperature is not greater than 30°C and less than or equal to 50°C (NO in step S203), that is, if the ambient temperature is less than or equal to 30°C or greater than 50°C, the control unit 13X proceeds to step S208.

[0086] (Step S204) The control unit 13X determines the threshold value of the set brightness in accordance with the ambient temperature (threshold value determination step).

[0087] (Step S205) If the set brightness exceeds the threshold (YES in step S205), the control unit 13X proceeds to step S206. If the set brightness does not exceed the threshold (NO in step S205), that is, if the set brightness is equal to or less than the threshold, the control unit 13X does not reduce the set brightness.

[0088] (Step S206) If the period during which the set brightness exceeds the threshold exceeds the predetermined period (YES in step S206), the control unit 13X proceeds to step S207. If the period during which the set brightness exceeds the threshold does not exceed the predetermined period (NO in step S206), the control unit 13X does not reduce the set brightness.

[0089] (Step S207) The control unit 13X reduces the brightness of the illumination unit 141 to the threshold value (threshold value reduction step).

[0090] After step S207 is completed, or if the set brightness is not reduced, the display device 1X may re-execute each step from step S201 described above, or may terminate the processing of each step without re-executing them.

[0091] (Step S208) The control unit 13X does not reduce the set brightness when the ambient temperature is equal to or lower than 30° C. If the ambient temperature is not equal to or lower than 30° C., that is, if the ambient temperature is higher than 50° C., the control unit 13X proceeds to step S209.

[0092] <Embodiment 3> The display device according to the present invention may, like the display device 1Y according to embodiment 3, maintain the brightness of the lighting unit 141 at a set brightness for a predetermined period of time, and then determine a threshold value for the set brightness based on the ambient temperature, and control whether or not to reduce the brightness of the lighting unit to the threshold value.

[0093] 7, 9, and 10, a display device 1Y according to the third embodiment 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 embodiments, and the description thereof will be omitted.

[0094] [Display device 1Y] Fig. 9 is a block diagram showing an example of the configuration of a display device 1Y. As shown in Fig. 9, the display device 1Y includes a detection unit 11Y and a control unit 13Y instead of the detection unit 11 and the control unit 13X in embodiment 2. Except for this, the display device 1Y according to embodiment 3 has the same configuration as the display device 1X according to embodiment 2.

[0095] [Control unit 13Y] The control unit 13Y maintains the luminance of the illumination unit 141 at the set luminance for a predetermined period of time. Thereafter, the control unit 13Y determines a threshold value for the set luminance based on the ambient temperature detected by the detection unit 11Y, and when the set luminance exceeds the threshold value, the control unit 13Y reduces the luminance of the illumination unit 141 to the threshold value.

[0096] 7, control unit 13Y maintains set brightness D2 at 100% until a predetermined period has elapsed, even if the ambient temperature rises to 50° C., and does not perform control to reduce the brightness of illumination unit 141 based on the ambient temperature. In this way, control unit 13X prioritizes maintaining the set brightness at set brightness D2 over controlling the brightness of illumination unit 141 to set brightness D1 based on the ambient temperature until a predetermined period has elapsed.

[0097] This makes it possible to improve the contrast and display quality of the image displayed on the display unit 14.

[0098] [Detection unit 11Y] The detector 11Y detects the ambient temperature of the illumination unit 141 after the controller 13Y has maintained the luminance of the illumination unit 141 at the set luminance for a predetermined period of time.

[0099] [Control method of display device 1Y] Next, a control method for the display device 1Y according to embodiment 3 will be described with reference to Fig. 10. Fig. 10 is a flowchart showing the control method for the display device 1Y according to embodiment 3. Steps S303, S304, S308, and S309 in Fig. 10 are similar to steps S202, S203, S205, S208, and S209 in Fig. 8, and therefore will not be described here.

[0100] In the example shown in Figure 10, it is assumed that the setting unit 12 of the display device 1Y has previously performed a setting process in which it sets the set brightness of the lighting unit 141 in the display unit 14 of the display device 1Y, and an illumination process in which the lighting unit 141 illuminates the area in the display unit 14 where an image is displayed.

[0101] (Step S301) The control unit 13Y of the display device 1Y maintains the luminance of the illumination unit 141 at the set luminance for a predetermined period of time (maintenance step).

[0102] (Step S302) After the control unit 13Y maintains the luminance of the illumination unit 141 at the set luminance for a predetermined period, the detection unit 11Y of the display device 1Y detects the ambient temperature of the illumination unit 141 (detection step).

[0103] (Step S305) The control unit 13Y determines a threshold value for the set brightness based on the ambient temperature detected by the detection unit 11Y (threshold value determination step).

[0104] (Step S306) If the set brightness exceeds the threshold value (YES in step S306), the control unit 13Y proceeds to step S307. If the set brightness does not exceed the threshold value (NO in step S306), the control unit 13Y does not reduce the set brightness.

[0105] (Step S307) The control unit 13Y reduces the brightness of the illumination unit 141 to the threshold value (threshold value reduction step).

[0106] After step S307 is completed, or if the set brightness is not reduced, the display device 1Y may re-execute each step from step S301 described above, or may terminate the processing of each step without re-executing them.

[0107] [Modification] In the above example, after the control unit 13Y maintains the luminance of the illumination unit 141 at the set luminance for a predetermined period, the detection unit 11Y detects the ambient temperature of the illumination unit 141. However, in the present embodiment, the detection unit 11Y may detect the ambient temperature before the predetermined period has elapsed.

[0108] In this case, the control unit 13Y maintains the luminance of the illumination unit 141 at the set luminance for a predetermined period, and then determines whether to reduce the luminance of the illumination unit 141 to the threshold value according to the threshold value of the set luminance determined based on the ambient temperature. This makes it possible to improve the contrast and display quality of the image displayed on the display unit 14, similar to the above example.

[0109] [Software implementation example] The control blocks of the display devices 1, 1X, and 1Y may be realized by a logic circuit (hardware) formed on an integrated circuit (IC chip) or the like, or may be realized by software.

[0110] In the latter case, the display devices 1, 1X, and 1Y each include a computer that executes instructions from a display control program, which is software that realizes each function. This computer includes, for example, at least one processor (control device) and at least one computer-readable recording medium storing the display control program. The object of the present invention is achieved by the computer having the processor read and execute the display control program from the recording medium. The processor may be, for example, a CPU (Central Processing Unit). The recording medium may be a "non-transitory tangible medium," such as a ROM (Read Only Memory), a tape, a disk, a card, a semiconductor memory, or a programmable logic circuit. The display device may also include a RAM (Random Access Memory) for storing the display control program. The display control program may be supplied to the computer via any transmission medium (such as a communication network or broadcast waves) capable of transmitting the display control program. One aspect of the present invention may also be realized in the form of a data signal embedded in a carrier wave, in which the display control program is embodied by electronic transmission.

[0111] 〔summary〕 A display device according to aspect 1 of the present invention includes an illumination unit, a detection unit that detects the ambient temperature of the illumination unit, a setting unit that sets the set brightness of the illumination unit, and a control unit that controls whether or not to maintain the brightness of the illumination unit at the set brightness based on the ambient temperature and the set brightness.

[0112] A display device according to aspect 2 of the present invention may be configured in the above-mentioned aspect 1 such that the control unit determines a maintenance period for the set brightness depending on the ambient temperature and the set brightness, and maintains the brightness of the lighting unit at the set brightness during the maintenance period.

[0113] A display device according to aspect 3 of the present invention may be configured in the above aspect 2 such that the control unit determines the maintenance period for the set brightness so that the ambient temperature of the lighting unit, which rises due to the amount of heat generated when the lighting unit is illuminated at the set brightness during the maintenance period, is below a predetermined temperature.

[0114] A display device according to aspect 4 of the present invention may be configured in the above-mentioned aspect 1 such that the control unit determines a threshold value for the set brightness in accordance with the ambient temperature, and reduces the brightness of the lighting unit to the threshold value if the period during which the set brightness exceeds the threshold exceeds a predetermined period.

[0115] A display device according to aspect 5 of the present invention may be configured such that, in aspect 1 above, the control unit maintains the brightness of the lighting unit at the set brightness for a predetermined period of time, and then determines a threshold value for the set brightness based on the ambient temperature, and if the set brightness exceeds the threshold value, reduces the brightness of the lighting unit to the threshold value.

[0116] A display device according to a sixth aspect of the present invention may be configured in any one of the first to fifth aspects, wherein the illumination section includes an LED (Light Emitting Diode).

[0117] A control method for a display device according to aspect 7 of the present invention includes an illumination step in which the display device illuminates using an illumination unit, a detection step in which the display device detects the ambient temperature of the illumination unit, a setting step in which the display device sets a set brightness of the illumination unit, and a control step in which the display device controls whether to maintain the brightness of the illumination unit at the set brightness based on the ambient temperature and the set brightness.

[0118] The display device according to each aspect of the present invention may be realized by a computer. In this case, the display control program for the display device that realizes the display device on a computer by causing the computer to operate as each part (software element) of the display device, and the computer-readable recording medium on which the program is recorded, also fall within the scope of the present invention.

[0119] [Modification] The present invention 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 invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0120] (Variation 1) The present invention may combine the first and second embodiments. In this case, the control unit of the display device determines, for example, a maintenance period for the set brightness depending on the ambient temperature and the set brightness, and a threshold value for the set brightness depending on the ambient temperature. The control unit also maintains the brightness of the lighting unit at the set brightness during the maintenance period, and reduces the brightness of the lighting unit to the threshold value if the period during which the set brightness exceeds the threshold exceeds the maintenance period.

[0121] In this way, as described above, by determining the maintenance period, maintaining the brightness of the lighting unit at the set brightness during the maintenance period, and then reducing the brightness of the lighting unit to the threshold value if the set brightness exceeds the threshold value, it is possible to more effectively prevent deterioration of the lighting unit while maintaining the set brightness as well as possible.

[0122] In the above example, the control unit determines the threshold value of the set brightness in accordance with the ambient temperature before maintaining the brightness of the illumination unit at the set brightness during the maintenance period. However, in the present embodiment, the control unit may determine the threshold value of the set brightness in accordance with the ambient temperature after maintaining the brightness of the illumination unit at the set brightness during the maintenance period. In this case, as in the above example, it is possible to prevent deterioration of the illumination unit and maintain the set brightness as optimally as possible.

[0123] (Variation 2) The present invention may combine the second and third embodiments. In this case, for example, the control unit of the display device determines a threshold value for the set brightness according to the ambient temperature. The control unit also maintains the brightness of the lighting unit at the set brightness for a predetermined period, and then reduces the brightness of the lighting unit to the threshold value if the period during which the set brightness exceeds the threshold exceeds the predetermined period.

[0124] In this way, in embodiment 3, the control unit determines the threshold value of the set brightness depending on the ambient temperature before maintaining the set brightness for a predetermined period of time, which can be combined with embodiments 2 and 3.

[0125] (Variation 3) The present invention may combine the first, second, and third embodiments. In this case, for example, the control unit of the display device determines a maintenance period for the set brightness according to the ambient temperature and the set brightness, and determines a threshold value for the set brightness according to the ambient temperature. The control unit maintains the brightness of the lighting unit at the set brightness during the maintenance period, and then reduces the brightness of the lighting unit to the threshold value if the period during which the set brightness exceeds the threshold exceeds the maintenance period.

[0126] This makes it possible to more effectively prevent deterioration of the illumination unit and maintain the set brightness of the illumination unit as well as possible, thereby improving the contrast and display quality of the image displayed on the display unit. [Explanation of symbols]

[0127] 1, 1X, 1Y display device 11, 11Y detection unit 12 Setting section 13, 13X, 13Y control unit 141 Lighting Department 14 Display section D1, D2 brightness setting

Claims

1. A lighting section, a detection unit that detects the ambient temperature of the illumination unit; a setting unit that sets a set brightness of the illumination unit; a control unit that controls whether or not the brightness of the illumination unit is maintained at the set brightness based on the ambient temperature and the set brightness, The control unit determining a threshold value for the set brightness based on the ambient temperature; maintaining the brightness of the illumination unit at the set brightness for a predetermined period of time regardless of the ambient temperature; A display device characterized in that, when the period during which the set brightness exceeds the threshold exceeds a predetermined period regardless of the ambient temperature, the brightness of the lighting unit is reduced to the threshold.

2. 2. The display device according to claim 1, wherein the predetermined period, regardless of the ambient temperature, is within a range that does not cause deterioration of the lighting unit when the lighting unit is illuminated at a set brightness exceeding the threshold value for the predetermined period, regardless of the ambient temperature.

3. The display device according to claim 1 , wherein the setting unit sets the set luminance in accordance with a pixel value of an image signal input to the display device.

4. 4. The display device according to claim 1, wherein the illumination unit includes an LED (Light Emitting Diode).

5. an illumination step in which the display device illuminates using an illumination unit; a detection step in which the display device detects an ambient temperature of the illumination unit; a setting step in which the display device sets a set brightness of the illumination unit; a control step of controlling whether or not the brightness of the illumination unit is maintained at the set brightness by the display device based on the ambient temperature and the set brightness, In the control step, determining a threshold value for the set brightness based on the ambient temperature; The brightness of the illumination unit is set to the predetermined value for a predetermined period regardless of the ambient temperature. Maintain brightness, A method for controlling a display device, comprising: reducing the brightness of the lighting unit to the threshold value when the period during which the set brightness exceeds the threshold value exceeds a predetermined period regardless of the ambient temperature.

6. 6. The display device control method according to claim 5, wherein the predetermined period, regardless of the ambient temperature, is within a range that does not cause deterioration of the lighting unit when the lighting unit is illuminated at a set brightness that exceeds the threshold value for the predetermined period, regardless of the ambient temperature.

7. 7. The display device control method according to claim 5, wherein in the setting step, the set luminance is set in accordance with a pixel value of an image signal input to the display device.

8. A threshold determination process for determining a threshold value for the set brightness of an illumination unit provided in a display device based on a detection result of an ambient temperature of the illumination unit; a process of maintaining the luminance of the illumination unit at the set luminance for a predetermined period of time regardless of the ambient temperature; and if the period during which the set brightness exceeds the threshold exceeds a predetermined period regardless of the ambient temperature, reducing the brightness of the lighting unit to the threshold.

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