JP2015111507A - Lighting device and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten, in a lighting device, a time required for a light source to reach a steady operation temperature.SOLUTION: A lighting device comprises: a light source; temperature detection means for detecting the temperature of the light source; and control means for controlling the luminance of the light source by adjusting the amount of current to be flown to the light source as well as a lighting period of the light source. If the temperature detected by the temperature detection means is lower than a threshold, the control means increases the amount of current to be flown to the light source and performs temperature rising control to shorten the lighting period of the light source.

Description

  The present invention relates to a lighting device and a control method thereof.

  There is a display using an LED (Light Emitting Diode) as a light source of a backlight. In addition, there is a display having high-precision color reproducibility by including LEDs of three primary colors of red, green, and blue and using the light emitted from these LEDs as a light source for a backlight.

  However, LEDs have a feature that the wavelength of emitted light changes depending on temperature. The display is designed so that optimum color reproducibility can be obtained at a steady operating temperature that is a saturation temperature during steady operation. Therefore, when the display is used, the user has to wait until the display temperature reaches the steady operating temperature when the display temperature is low.

  As a technique for shortening the time required to reach the steady operating temperature, in Patent Document 1, when the temperature of the light source is equal to or lower than a certain value, the heat generation amount is increased by causing the light source to emit light with a duty ratio of 100%. Is disclosed. Patent Document 2 discloses that when the temperature of a light source is equal to or lower than a certain value, the cooling performance is lowered by reducing the number of revolutions of the cooling fan to shorten the time required to reach the steady operating temperature.

JP 2007-148095 A Japanese Patent Laid-Open No. 11-259001

  However, in the prior art disclosed in Patent Document 1 described above, the brightness of the display screen increases, and the user may feel uncomfortable. In the prior art disclosed in Patent Document 2, since the cooling performance of the entire display is lowered, there is a problem that the temperature of peripheral circuits other than the light source rises.

  Therefore, an object of the present invention is to shorten the time until the temperature of the light source reaches the steady operating temperature in the lighting device.

The present invention comprises a light source;
Temperature detecting means for detecting the temperature of the light source;
Control means for controlling the luminance of the light source by adjusting the amount of current flowing to the light source and the lighting period of the light source;
A lighting device comprising:
When the temperature detected by the temperature detection unit is lower than a threshold value, the control unit performs temperature increase control for increasing the amount of current flowing to the light source and decreasing the lighting period of the light source. It is.

The present invention is a method for controlling a lighting device including a light source,
A temperature detection step of detecting the temperature of the light source;
A control step of controlling the luminance of the light source by adjusting the amount of current flowing to the light source and the lighting period of the light source;
Have
In the control step, when the temperature detected by the temperature detection step is lower than a threshold value, temperature control is performed to increase the amount of current flowing to the light source and reduce the lighting period of the light source. This is a control method.

  ADVANTAGE OF THE INVENTION According to this invention, time until the temperature of a light source reaches steady operation temperature in an illuminating device can be shortened.

Configuration diagram of backlight module of Example 1 Flowchart of the backlight module of the first embodiment Configuration diagram of backlight module of Example 2 Flowchart of Backlight Module of Example 2 Configuration diagram of backlight module of Example 3 Flowchart of Backlight Module of Example 3

Example 1 of an illumination device according to the present invention will be described below with reference to the drawings.
Example 1
FIG. 1 is a configuration diagram of a backlight module 100 that is an illumination apparatus according to Embodiment 1 of the present invention. The backlight module 100 includes a drive circuit unit 101, an LED 102, a drive control unit 103, a temperature sensor 104, and a luminance sensor 105. This backlight module can be used as a backlight device of a MEMS shutter system display using a liquid crystal display device or a MEMS (Micro Electro Mechanical System) shutter, for example.

  The drive circuit unit 101 includes a constant current circuit that can change the amount of current. The drive circuit unit 101 drives the LED 102 by PWM (pulse width modulation) control. In the PWM control, the luminance of the light source is controlled by adjusting the lighting period (PWM width) of the light source and the amount of current within a certain period. The adjustment of the PWM width can also be referred to as adjustment of the duty ratio, which is the ratio of the lighting period to one cycle. Increasing the lighting period, PWM width, and duty ratio increases the luminance of the light source. Further, the luminance is increased by increasing the amount of current. The drive circuit unit 101 drives the LED 102 with the PWM width and current amount specified by the drive control unit 103.

LED102 is comprised by the board | substrate with which the LED element was mounted. The LED 102 is driven by the drive circuit unit 101 to emit light.
The temperature sensor 104 is disposed at a position where the temperature of the LED 102 on the substrate can be detected. The temperature sensor 104 converts temperature into a voltage value or a current value, and is constituted by, for example, a thermistor and an amplifier.
The brightness sensor 105 is disposed at a position where the light emission brightness of the LED 102 can be detected, for example. The luminance sensor 105 converts luminance into a voltage value or a current value, and is constituted by, for example, a photodiode or a phototransistor and an amplifier.

The drive control unit 103 includes an MPU (Micro-Processing Unit) and a memory. The drive control unit 103 receives user setting luminance information that is information of luminance setting set by the user using an input device (not shown). The drive control unit 103 sends a PWM control signal and a current amount control signal based on the user-set luminance information to the drive circuit unit 101 at the time of initial startup. The drive control unit 103 reads the outputs of the temperature sensor 104 and the brightness sensor 105 at regular intervals. The drive control unit 103 changes the current amount control signal according to the value of the temperature sensor 104. The drive control unit 103 changes the PWM control signal according to the value of the luminance sensor 105. The drive control unit 103 has information on the steady operation temperature Tc as a temperature threshold inside. The steady operating temperature Tc is a temperature at which the LED 102 emits light of an intended wavelength, and is determined in advance. Information on the steady operating temperature Tc may be stored in a storage device such as a nonvolatile memory.

Next, the operation will be described using the flowchart according to the first embodiment of the present invention shown in FIG.
In step S <b> 101, the drive control unit 103 receives user setting luminance information that is information on luminance setting set by the user using an input device (not shown). Here, the set brightness by the user is A. As the user-set luminance information, information corresponding to the set luminance is stored in the memory when the user sets the luminance with the input device. The drive control unit 103 reads user setting luminance information from the memory. Next, the process proceeds to step S102.

  In step S102, the drive control unit 103 acquires a current amount B and a PWM width C corresponding to the user-set luminance information based on a table that is stored in advance. The drive control unit 103 sends a current amount control signal for setting the current amount B and a PWM control signal for setting the PWM width C to the drive circuit unit 101. Next, the process proceeds to step S103.

  In step S <b> 103, the drive circuit unit 101 drives the LED 102 based on the PWM control signal and the current control signal received from the drive control unit 103. Next, it progresses to step S104.

  In step S <b> 104, the drive control unit 103 acquires the outputs of the temperature sensor 104 and the luminance sensor 105. The drive control unit 103 acquires the detected temperature Ta of the LED 102 corresponding to the output of the temperature sensor 104 based on a table that is held in advance. The drive control unit 103 acquires the detected light emission luminance D of the LED 102 corresponding to the output of the luminance sensor 105 based on a table that is held in advance. Next, the process proceeds to step S105.

In step S105, the drive control unit 103 divides the set luminance A by the detected light emission luminance D to calculate the PWM correction value A / D. Further, the drive control unit 103 calculates a corrected PWM width E obtained by multiplying the PWM width C by the PWM correction value A / D. The drive control unit 103 sends a PWM control signal for setting the corrected PWM width E to the drive circuit unit 101. Next, the process proceeds to step S106.

  In step S106, the drive control unit 103 compares the preset steady operation temperature Tc with the detected temperature Ta. If the detected temperature Ta is lower than the steady operating temperature Tc (Yes), the process proceeds to step S107. If the detected temperature Ta is equal to or higher than the steady operating temperature Tc (No), the process proceeds to step S108.

  In step S <b> 107, the drive control unit 103 sends a current control signal for setting the current amount F to the drive circuit unit 101. The amount of current F is determined based on the maximum amount of current that the drive circuit unit 101 can output or the maximum amount of current that the LED 102 can allow. The amount of current F does not have to be equal to the maximum amount of current as long as the power consumption of the LED 102 increases as compared with the normal time. Next, it progresses to step S104.

  In step S <b> 108, the drive control unit 103 sends a current amount control signal for setting the current amount B to the drive circuit unit 101. That is, after the temperature increase control is executed, when the detected temperature Ta of the LED 102 becomes equal to or higher than the steady operation temperature Tc, the PWM width and current amount before the temperature increase control are returned. Next, the process proceeds to the end step.

  With the above operation, when the backlight module 100 is in a low temperature state at the time of initial startup (when Yes in S106), the amount of current flowing through the LED 102 increases, so that the light emission efficiency of the LED 102 decreases and the amount of heat generation increases. Thereby, temperature increase control for increasing the temperature of the LED 102 is executed. By executing the temperature increase control, the time until the temperature of the LED 102 reaches the steady operating temperature can be shortened. Thereby, when the backlight is activated or when the image display apparatus including the backlight is activated, the state in which the temperature of the LED 102 is lower than the steady operation temperature can be quickly eliminated. Accordingly, it is possible to shorten a period in which the luminance and chromaticity of the display image are shifted due to the shift of the emission wavelength from the assumed emission wavelength at the time of activation.

  At this time, the PWM width is adjusted so that the luminance of the LED 102 does not change before and after the temperature increase control is executed (usually, the PWM width is adjusted to be smaller than before the current amount is increased). Thereby, even if it performs temperature rising control, since the light emission brightness | luminance of LED102 can be kept constant, it can suppress that a user feels uncomfortable. And since the electric current amount of LED102 is increased, only the temperature of LED102 can be raised and the temperature rise of a peripheral circuit can be suppressed.

  In S107 of the above flow, the PWM width E corrected in S105 may be decreased in accordance with the increase in the current amount from B to F. For example, by reducing and correcting the corrected PWM width to E × B / F, the luminance change of the LED 102 due to an increase in the amount of current can be suppressed.

  In this embodiment, when the temperature Ta of the LED is lower than the steady operation temperature Tc, an example of executing the temperature rise control for increasing the LED temperature by increasing the LED current amount and shortening the LED lighting period. Explained. This is a control aiming to raise the temperature of the backlight in a low temperature state at the time of startup to the steady operating temperature at an early stage, but the backlight temperature may be higher than the steady operating temperature during the use process. In that case, it is necessary to lower the temperature of the backlight to the steady operating temperature. Therefore, when the LED temperature Ta is higher than the steady operating temperature Tc, the temperature drop control may be executed to decrease the LED temperature by decreasing the LED current amount and extending the LED lighting period. Further, in the temperature determination for determining whether or not the temperature increase control or the temperature decrease control needs to be performed, it may be determined whether or not the LED temperature Ta is within a predetermined range including the steady operation temperature Tc. That is, the temperature increase control may be executed when the LED temperature Ta is lower than the temperature range [T1, T2], and the temperature decrease control may be executed when the LED temperature Ta is higher. Here, T1 and T2 are values that satisfy T1 <Tc <T2, and the temperature range [T1, T2] is a temperature range in which the deviation of the emission wavelength of the LED from the target is within an allowable range. The temperature range may be variable depending on the use of the backlight. For example, if the image display device can switch between an image quality mode that requires high color reproducibility and an image quality mode that does not require such high color reproducibility, the former image quality mode narrows the temperature range and the latter image quality mode. In the mode, the temperature range may be widened.

(Example 2)
According to the first embodiment, it is possible to quickly eliminate the deviation of the emission wavelength due to the low temperature state of the light source at the initial startup. However, even when the backlight is in operation, it may deviate from the steady operating temperature due to disturbances such as the outside air temperature and operating conditions. In addition, color unevenness may occur due to a difference in temperature for each backlight region.
In the second embodiment, an embodiment will be described in which the temperature difference for each region of the backlight is eliminated in a short time and the backlight can be operated at a steady operating temperature.

The second embodiment of the present invention will be described below with reference to the drawings.
FIG. 3 is a configuration diagram of the backlight module 200 according to the second embodiment of the present invention. The backlight module 200 includes a drive circuit unit 201, a drive control unit 203, and a plurality of LED units 206, 210,. The LED unit 206 includes an LED 202, a temperature sensor 204, and a luminance sensor 205. The LED unit 210 includes an LED 207, a temperature sensor 208, and a luminance sensor 209. Other LED units (not shown) have the same configuration. The LED of each LED unit is composed of a plurality of light emitting elements having different emission wavelengths, that is, LEDs of three primary colors of red LED, green LED, and blue LED. The light emission of each LED of the three primary colors can be controlled independently.

  The LED units 206, 210,... Are composed of LEDs 202, 207, which will be described later, temperature sensors 204, 208, and luminance sensors 205, 209,. There are n LED units 206, 210... In the backlight module 200 (n is an integer of 2 or more).

  The LEDs 202, 207,... Are constituted by a substrate on which a plurality of LED elements are mounted. The LEDs 202, 207,... Are individually connected to the drive circuit unit 201, respectively. That is, the LEDs of each LED unit can independently control the light emission.

  The temperature sensors 204, 208,... Are arranged in total for each LED unit at positions where the temperatures of the LEDs 202, 207,. That is, the temperature sensors 204, 208,... Are configured to be able to detect the temperature for each light source. The temperature sensors 204, 208,... Convert the temperature into a voltage value or a current value, and are composed of, for example, a thermistor and an amplifier.

  The brightness sensors 205, 209,... Are arranged in a total of n for each LED unit, for example, at positions where the light emission brightness of the LEDs 202, 207,. The luminance sensors 205, 209,... Convert the luminance into a voltage value or a current value, and are constituted by, for example, a photodiode or a phototransistor and an amplifier.

  The drive circuit unit 201 is configured by a constant current circuit. The drive circuit unit 201 drives the LEDs 202, 207,... In the n LED units 206, 210,... With the PWM width and current amount specified by the drive control unit 203, respectively. That is, the drive circuit unit 201 is configured to be able to adjust the PWM width and the current amount for each light source.

  The drive control unit 203 includes an MPU and a memory. The drive control unit 203 stores the current amounts and PWM widths set in the LEDs 202, 207,... In the n LED units 206, 210,. The drive control unit 203 sequentially reads the outputs of the n temperature sensors 204, 208,... At regular intervals. The drive control unit 203 has information on the temperature T1 and the temperature T2 in the relationship of the steady operation temperature Tc and T1 <Tc <T2. T1 and T2 are a lower limit value and an upper limit value of the operating temperature of the LED that can allow deviation from the target wavelength of the emitted light of the LED, and are determined in advance. The drive control unit 203 changes the current amount control signal or PWM control signal of the red LED according to the values of the temperature sensors 204, 208. The drive control unit 203 reads the outputs of the luminance sensors 205, 209,. The drive control unit 203 changes the current amount control signal or PWM control signal of the red LED according to the values of the luminance sensors 205, 209.

Next, operation | movement of the illuminating device of Example 2 of this invention is demonstrated using the flowchart of FIG.
In step S201, the drive control unit 203 sets the set luminance A, the current amount B, and the PWM width set for the LEDs 202, 207,... In the n LED units 206, 210,. Remember C. Next, the process proceeds to step S202.

  In step S202, the drive control unit 203 substitutes 1 for a variable M held therein. Next, the process proceeds to step S203. The variable M is a numerical value that specifies what number LED unit is the processing target, and takes a value of 1 to n.

  In step S203, the drive control unit 203 acquires the output of the temperature sensor that constitutes the Mth LED unit among the n temperature sensors 204, 208,. The drive control unit 203 acquires a detected temperature Tm corresponding to the acquired value based on a table that is held in advance. The detected temperature Tm is the temperature of the Mth LED unit among the LED units 206, 210. Next, the process proceeds to step S204.

  In step S204, the drive control unit 203 compares the detected temperatures Tm and T1 acquired in step S203. If Tm is smaller than T1 (Yes), the process proceeds to step S205. If the detected temperature Tm is equal to or higher than T1 (No), the process proceeds to step S208.

  In step S205, the drive control unit 203 outputs a current control signal for setting the current amount F to be the amount of current that flows through the red LED among the LEDs constituting the Mth LED unit of the LED units 206, 210. This is sent to the drive circuit unit 201. The current amount F is a maximum current value that can be output by the drive circuit unit 201 or a maximum current value that can be allowed by the LEDs 202, 207. If the power consumption of the LEDs 202, 207,... Increases more than usual, the current value F need not be equal to these maximum current amounts. Next, the process proceeds to step S206.

  In step S206, the drive control unit 203 acquires the sensor output of the luminance sensor that constitutes the Mth LED unit among the LED units 206, 210. The drive control unit 203 acquires a detected luminance lm corresponding to the acquired value based on a table that is held in advance. The detection luminance lm is the luminance of the LED constituting the Mth LED unit among the LED units 206, 210. Next, the process proceeds to step S207.

In step S207, the drive control unit 203 calculates the PWM correction value A / lm by dividing the set luminance A by the detected luminance lm. Further, the drive control unit 203 calculates the corrected PWM width E by multiplying the PWM width C by the PWM correction value A / lm. The drive control unit 203 sends to the drive circuit unit 201 a PWM control signal for setting the corrected PWM width E to the red LED among the LEDs constituting the Mth LED unit among the LED units 206, 210. . Next, the process proceeds to step S203. Since the amount of current is set to the maximum value, the amount of heat generated by the LED increases and the temperature of the LED unit increases.

  On the other hand, if the detected temperature Tm is equal to or higher than T1 in step S204, the drive control unit 203 compares the detected temperature Tm acquired in step S203 with T2 in step S208. If Tm is greater than T2 (Yes), the process proceeds to step S209. If Tm is equal to or less than T2 (No), the process proceeds to step S212.

  In step S209, the drive control unit 203 sets the PWM width set to the red LED among the LEDs constituting the Mth LED unit among the LED units 206, 210. A signal is sent to the drive circuit unit 201. This PWM width may be less than 100% as long as the PWM width of the LEDs 202, 207,... Next, the process proceeds to step S210.

In step S210, the drive control unit 203 acquires the sensor output of the luminance sensor that constitutes the Mth LED unit among the LED units 206, 210. The drive control unit 203 detects the detected luminance l corresponding to the acquired value based on a table that is held in advance.
Get m. The detection luminance lm is the luminance of the LED constituting the Mth LED unit among the LED units 206, 210. Next, it progresses to step S211.

In step S211, the drive control unit 203 calculates the current amount correction value A / lm by dividing the set luminance A by the detected luminance lm. Further, the drive control unit 203 calculates the corrected current amount G by multiplying the current amount B by the current amount correction value A / lm. The drive control unit 203 includes the LED unit 2
The current amount control signal for setting the corrected current amount G to the red LED among the LEDs constituting the Mth LED unit among 06, 210... Is sent to the drive circuit unit 201. Next, the process proceeds to step S203. Since the PWM width is set to 100% and the amount of current decreases accordingly, the amount of heat generated by the LED decreases, and the temperature of the LED unit decreases.

  On the other hand, when the detected temperature Tm is equal to or lower than T2 in step S208, in step S212, the drive control unit 203 determines the LED constituting the Mth LED unit among the LED units 206, 210,. The setting is returned to the current amount B and the PWM width C. That is, a current amount control signal for setting the current amount B and a PWM control signal for setting the PWM width C are sent to the drive circuit unit 201. That is, when the detected temperature Tm of the LED falls within a predetermined temperature range including the steady operation temperature Tc after the temperature increase control or the temperature decrease control is executed, the PWM width before the temperature increase control or the temperature decrease control is executed. And returned to the amount of current. Next, the process proceeds to step S213.

  In step S213, the drive control unit 203 determines whether or not the value of an internal variable M is n. If M ≠ n, the process proceeds to step S214. If M = n, the process proceeds to the end step.

  In step S214, the drive control unit 203 increments an internal variable M (substitutes a value of M + 1). Next, the process proceeds to step S203.

  By the above operation, the backlight module 200 adjusts the amount of current and the PWM width for each LED unit even when a temperature difference occurs between the LED units 206, 210. Thereby, the emitted-heat amount for every unit can be increased / decreased, keeping the brightness | luminance of the area | region corresponding to each LED unit of a backlight constant. Thereby, it is possible to keep the temperature of the backlight light source at the steady operating temperature for each LED unit.

  In the present embodiment, an example of controlling the amount of heat generated by the LED unit by changing the drive setting of the red LED is shown. This is because the red LED is an LED having a different emission wavelength due to a change in the amount of current. It is because it is small compared with. Therefore, even if the drive setting is changed for temperature control, the backlight color hardly changes. In applications where accurate color reproducibility is required, image processing is performed so that the display chromaticity does not change in consideration of slight changes that occur in the color of the backlight by changing the drive setting of the red LED. It may be used for performing. In addition, the LED drive setting with a small change in emission wavelength due to a change in the amount of current may be changed together with the red LED drive setting.

(Example 3)
In the present embodiment, an embodiment will be described in which the necessity of executing the process of controlling the temperature of each LED unit (each region) of the backlight described in the second embodiment to the steady operating temperature is adaptively determined for each region.
Depending on the display use case, high-precision color reproducibility is not always required on the entire screen. For example, high-precision color reproducibility is often not required in an area where a menu screen or status display is displayed. Therefore, in the present embodiment, the control according to the second embodiment is performed only in a divided area where an image requiring high-precision color reproducibility is displayed among a plurality of divided areas that divide the display area of the image display device including the backlight. Execute. In other divided areas, L
Without performing temperature rise control or high temperature control according to the temperature of the ED, the power consumption is suppressed by improving the light emission efficiency by maximizing the PWM width and reducing the current amount. As described above, in this embodiment, whether to perform the temperature increase control or the temperature decrease control according to the LED temperature is switched according to the image displayed in the corresponding divided region.

Hereinafter, a third embodiment of the present invention will be described focusing on differences from the second embodiment with reference to the drawings.
FIG. 5 is a configuration diagram of the backlight module 300 according to the third embodiment of the present invention. The backlight module 300 includes a drive circuit unit 201, a drive control unit 303, and a plurality of LED units 206, 210,. The LED unit 206 includes an LED 202, a temperature sensor 204, and a luminance sensor 205. The LED unit 210 includes an LED 207, a temperature sensor 208, and a luminance sensor 209. The drive control unit 303 is connected to an external GUI control unit 306.

  The GUI control unit 306 is a functional block for displaying a GUI (Graphical User Interface) on the display screen, and is connected to a functional block that performs display control (not shown). The functional block that performs display control is provided in a display including the backlight module 300, for example. Here, the GUI is displayed when the user operates an operation button provided on the display in order to perform display setting or the like of the display. The GUI has a color reproducibility with higher accuracy than the display for image editing or the like. Not required. The GUI control unit 306 sends GUI display area information to the drive control unit 303. The GUI display area information is position information (coordinate information) of an area where the GUI is displayed in the screen.

  Based on the GUI display area information sent from the GUI control section 306, the drive control section 303 determines which of the n LED units 206, 210... Is responsible for the GUI display area. The drive control unit 303 changes the PWM width of the LED constituting the LED unit determined to be in charge of the GUI display area to 100%, and changes in luminance due to the change of the PWM width to 100%. Correct the amount of current so that there is no current. Note that the PWM width after the change is not limited to 100% as long as it is larger than that before the change.

Other functional blocks are the same as those in the second embodiment.
Next, the operation of the lighting apparatus according to the third embodiment of the present invention will be described with reference to the flowchart of FIG.
In step S301, the drive control unit 303 acquires GUI display area information from the GUI control unit 306, and which LED unit among the n LED units 206, 210,... Is in charge of the GUI display area. judge. The drive control unit 303 stores information on the LED unit in charge of the GUI display area in the memory. Next, the process proceeds to step S201.

  In step S <b> 302, the drive control unit 303 determines whether the Mth unit is in charge of the GUI display area stored in step S <b> 301. If the LED unit is not in charge of the GUI display area (No), the process proceeds to step S203. If the LED unit is in charge of the GUI display area (Yes), the process proceeds to step S303.

  In step S <b> 303, the drive control unit 303 sends a PWM control signal for setting the PWM width of the red LED of the LEDs constituting the Mth LED unit to 100% to the drive circuit unit 201. Next, the process proceeds to step S304.

In step S304, the drive control unit 303 acquires the sensor output of the luminance sensor that constitutes the Mth LED unit. The drive control unit 303 acquires a detected luminance lm corresponding to the acquired value based on a table that is held in advance. The detected luminance lm is the luminance of the LED constituting the Mth unit. Next, the process proceeds to step S305.

In step S305, the drive control unit 303 divides the set luminance A by the detected luminance lm to calculate a current amount correction value A / lm. Further, the drive control unit 303 calculates the corrected current amount G by multiplying the current amount B by the current amount correction value A / lm. The drive control unit 303 sends a current amount control signal for setting the corrected current amount G to the red LED among the LEDs constituting the Mth LED unit to the drive circuit unit 201. Next, it progresses to step S213.
Other operations are the same as those in the second embodiment.

With the above operation, the temperature of the LED unit corresponding to the display area requiring high-precision color reproducibility can be maintained at the steady operating temperature, and the LED corresponding to the display area not requiring high-precision color reproducibility. The unit can be used in a state where the luminous efficiency is good.
Therefore, according to the present invention, it is possible to suppress power consumption while maintaining the temperature of the backlight light source of the LED unit that requires highly accurate color reproducibility at a steady operating temperature.

  In the present embodiment, an example has been described in which whether or not a display area is required to have high-precision color reproducibility is determined based on whether or not it is a GUI display area such as a menu. It is not limited to this. For example, it is possible to determine whether the display area is a natural image display area such as a photograph or a graphics image display area such as CG. Alternatively, it can be determined by the type of application such as the display area of the image editing application or the display area of the document creation application. Alternatively, it can also be determined by the color of the image such as whether it is a monochrome image display area or a color image display area. Alternatively, it is possible to determine whether the display area is a medical image display area or an image display area other than that. Based on the type of the display image and the like, it is possible to switch, for each region, whether to give priority to the temperature of the light source or the power consumption. In this case, the determination of which type of image is displayed in which region may be performed by the image display device by image processing or the like, or from the image output device that inputs the image to the image display device, The type and display position information may be acquired.

100, 200, 300: Backlight module 102, 202, 207: LED
103, 203, 303: Drive control unit 104, 204, 208: Temperature sensor 206, 210: LED unit

Claims (25)

A light source;
Temperature detecting means for detecting the temperature of the light source;
Control means for controlling the luminance of the light source by adjusting the amount of current flowing to the light source and the lighting period of the light source;
A lighting device comprising:
When the temperature detected by the temperature detection unit is lower than a threshold value, the control unit performs temperature increase control for increasing the amount of current flowing to the light source and decreasing the lighting period of the light source. .   The lighting device according to claim 1, wherein the control unit increases an amount of current and decreases a lighting period in the temperature increase control so that luminance of the light source does not change before and after execution of the temperature increase control.   The lighting device according to claim 1, wherein the control unit increases the current amount up to a maximum current amount allowed by the light source in the temperature increase control.   The lighting device according to any one of claims 1 to 3, wherein the control means executes the temperature increase control when the lighting device is activated.   The lighting device according to claim 1, wherein the threshold value is a steady operating temperature of the lighting device. The light source is composed of a plurality of light emitting elements having different emission wavelengths,
The control means controls the luminance of the light emitting element by adjusting the amount of current flowing through the light emitting element and the lighting period of the light emitting element,
The lighting device according to any one of claims 1 to 5, wherein the control unit performs the temperature increase control on a light emitting element having the smallest change in emission wavelength when the amount of current is changed.   7. The temperature control according to claim 1, wherein when the temperature detected by the temperature detection unit is higher than a threshold value, the control unit performs a temperature decrease control for decreasing a current amount flowing through the light source and increasing a lighting period of the light source. The lighting device according to item 1.   The lighting device according to claim 7, wherein the control unit reduces the amount of current and increases the lighting period in the temperature decrease control so that the luminance of the light source does not change before and after the execution of the temperature decrease control.   The lighting device according to claim 7, wherein the control unit sets a lighting period of the light source as a maximum lighting period in the temperature lowering control. The light source is composed of a plurality of light emitting elements having different emission wavelengths,
The control means controls the luminance of the light emitting element by adjusting the amount of current flowing through the light emitting element and the lighting period of the light emitting element,
The lighting device according to any one of claims 7 to 9, wherein the control unit performs the temperature lowering control on a light emitting element having a smallest change in light emission wavelength when the amount of current is changed.   The control means performs the temperature rise control when the temperature detected by the temperature detection means is lower than a predetermined temperature range including a threshold, and when the temperature detected by the temperature detection means is higher than the temperature range. The lighting device according to claim 7, wherein the temperature lowering control is performed.   The temperature range is a temperature range in which a deviation of an emission wavelength of the light source with respect to an emission wavelength of the light source is within an allowable range when a temperature of the light source is a steady operating temperature of the lighting device. Lighting device.   When the temperature detected by the temperature detection unit becomes a temperature within the temperature range after the temperature increase control or the temperature decrease control is performed, the control unit determines the amount of current flowing through the light source and the lighting period of the light source. The lighting device according to claim 11 or 12, wherein the current is returned to the amount of current and the lighting period before execution of the temperature increase control or the temperature decrease control. The lighting device has a plurality of light sources,
The temperature detection means detects the temperature of each light source,
The said control means can adjust independently the electric current amount and the lighting period of each light source which flow through each light source, and performs the said temperature rising control according to the temperature of a light source for every light source. The lighting device according to item 1. Each of the plurality of light sources corresponds to each of a plurality of divided regions that divide a display region of an image display device including the illumination device as a backlight,
The illumination according to claim 14, wherein the control means switches whether to execute the temperature increase control according to the temperature of the light source for each light source, according to an image displayed in a divided region corresponding to each light source. apparatus.   The lighting device according to claim 15, wherein the control unit maximizes a lighting period and decreases a current amount for a light source that does not execute the temperature increase control according to the temperature of the light source.   The illumination device according to claim 15 or 16, wherein the control means does not execute the temperature increase control according to the temperature of the light source for a light source in which an image displayed in a corresponding divided region is an image constituting a GUI. The lighting device has a plurality of light sources,
The temperature detection means detects the temperature of each light source,
The said control means can adjust independently the electric current amount sent to each light source, and the lighting period of each light source, and performs the said temperature rise control or the said temperature fall control according to the temperature of a light source for every light source. 14. The lighting device according to any one of 13. Each of the plurality of light sources corresponds to each of a plurality of divided regions that divide a display region of an image display device including the illumination device as a backlight,
The control means switches whether to execute the temperature increase control or the temperature decrease control according to the temperature of the light source for each light source according to an image displayed in a divided region corresponding to each light source. The lighting device described in 1.   The lighting device according to claim 19, wherein the control means maximizes the lighting period and decreases the amount of current for a light source that does not execute the temperature increase control or the temperature decrease control according to the temperature of the light source.   The said control means does not perform the said temperature increase control or the said temperature decrease control according to the temperature of a light source about the light source whose image displayed on a corresponding division area is an image which comprises GUI. Lighting equipment. A method for controlling an illumination device including a light source,
A temperature detection step of detecting the temperature of the light source;
A control step of controlling the luminance of the light source by adjusting the amount of current flowing to the light source and the lighting period of the light source;
Have
In the control step, when the temperature detected by the temperature detection step is lower than a threshold value, temperature control is performed to increase the amount of current flowing to the light source and reduce the lighting period of the light source. Control method.   The lighting device according to claim 22, wherein, in the control step, when the temperature detected by the temperature detection step is higher than a threshold value, a temperature drop control is performed to decrease an amount of current flowing to the light source and increase a lighting period of the light source. Control method. The lighting device has a plurality of light sources,
In the temperature detection step, the temperature of each light source is detected,
24. In the control step, the amount of current flowing to each light source and the lighting period of each light source can be adjusted independently, and the temperature increase control or the temperature decrease control is executed for each light source according to the temperature of the light source. The control method of the illuminating device described. Each of the plurality of light sources corresponds to each of a plurality of divided regions that divide a display region of an image display device including the illumination device as a backlight,
25. In the control step, according to an image displayed in a divided region corresponding to each light source, whether to perform the temperature increase control or the temperature decrease control according to the temperature of the light source is switched for each light source. The control method of the illuminating device of description.

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