JP2014182291A - Light emission device and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for holding the uniformity of backlight luminance even when an optical sensor breaks down.SOLUTION: A light emission device includes: light emission means constituted of a plurality of light emission regions capable of independently controlling light emission; control means for controlling the emitted light quantity of each light emission region; a plurality of luminance detection means for detecting the luminance of each light emission region; storage means for storing the target value of the luminance of each light emission region; and correction means for correcting the emitted light quantity of each light emission region such that the luminance detected by each luminance detection means is made close to the target value. When there exists luminance detection means which has broken down among the plurality of luminance detection means, the correction means estimates the luminance of the light emission region corresponding to the luminance detection means which has broken down on the basis of the luminance detected by the luminance detection means which does not break down, and corrects the emitted light quantity of the light emission region corresponding to the luminance detection means which has broken down on the basis of the estimated luminance.

Description

  The present invention relates to a light emitting device capable of detecting the light emission intensity of a light source using an optical sensor and controlling the luminance characteristics of the light source, and a control method thereof.

In recent years, as a backlight of a liquid crystal display device, a light emitting diode (Light Emitting).
ng Diode (hereinafter abbreviated as LED)). In particular, an installation method called a direct type in which LEDs are arranged in an array on the back side of the liquid crystal is a local light intensity adjustment for each control unit (which is a control unit for the amount of current and is composed of a single or a plurality of LEDs). Is relatively easy. Therefore, it is possible to improve the contrast ratio (the ratio between the maximum luminance and the minimum luminance) and reduce the power consumption by local dimming (local dimming), and it is rapidly spreading.

  On the other hand, as general characteristics of LEDs, initial variation, aging deterioration, and temperature deterioration are large, and it has been difficult to keep the brightness of the backlight constant and uniform over a long period of time with the above-described direct type LED arrangement. Therefore, a light sensor is attached in the vicinity of the backlight, the emission intensity is detected for each control unit, and the current value of the backlight is corrected so that the detected value approaches the predetermined target value. Has been proposed (see, for example, Patent Document 1).

JP 2008-123818 A

  However, when a plurality of optical sensors are mounted in this way, there is a problem that even if one of the optical sensors fails, the uniformity of the backlight luminance is impaired due to erroneous detection of the emission intensity.

  Therefore, an object of the present invention is to provide a technique that makes it possible to maintain the uniformity of backlight luminance even when an optical sensor fails.

The present invention comprises a light emitting means comprising a plurality of light emitting regions that can independently control light emission,
Control means for controlling the light emission amount of each light emitting region;
A plurality of luminance detecting means for detecting the luminance of each light emitting region;
Storage means for storing a target value of luminance of each light emitting area;
Correction means for correcting the light emission amount of each light emitting region so that the brightness detected by each brightness detection means approaches the target value;
With
In the case where there is a malfunction among the plurality of brightness detection means, the correction means emits light corresponding to the malfunctioning brightness detection means based on the brightness detected by the brightness detection means not malfunctioning. The light emitting device is characterized in that the luminance of the area is estimated, and the light emission amount of the light emitting area corresponding to the malfunctioning luminance detecting means is corrected based on the estimated luminance.

The present invention is a method for controlling a light emitting device, comprising: a light emitting unit including a plurality of light emitting regions that can independently control light emission; and a plurality of luminance detecting units that detect luminance of each of the light emitting regions. A control process for controlling the amount of light emitted from the region;
Detecting the luminance of each light emitting region by a corresponding luminance detecting means;
Obtaining a target value of luminance of each light emitting area from a storage means;
A correction step of correcting the light emission amount of each light emitting region so that the luminance detected by each luminance detection means approaches the target value;
Have
In the correction step, when there is a malfunction among the plurality of brightness detection means, the light emission corresponding to the malfunctioned brightness detection means is based on the brightness detected by the brightness detection means that is not malfunctioning. A method for controlling a light emitting device, comprising: estimating a luminance of a region, and correcting a light emission amount of a light emitting region corresponding to a malfunctioning luminance detecting unit based on the estimated luminance.

  According to the present invention, it is possible to maintain the uniformity of backlight luminance even when the optical sensor fails.

FIG. 3 is a block diagram illustrating a schematic configuration of the light emitting device according to the first embodiment. The schematic diagram which shows the arrangement configuration of the light-emitting device of Example 1. FIG. Flowchart at the time of recording target light sensor value and initial sensor history information according to embodiment 1 The flowchart explaining the operation | movement at the time of the optical sensor value log | history information update of Example 1. FIG. 6 is a flowchart for explaining the operation of adjusting the light emission intensity of the light emitting device according to the first embodiment. The figure which shows distribution of the average brightness | luminance for every control area with respect to the target brightness | luminance of Example 1. FIG. Example 1 Initial Current Value Information, Target Optical Sensor Value Information, Optical Sensor Detection Value The figure which shows the initial optical sensor value log | history information of Example 1. The figure which shows the optical sensor value log | history information after the update of Example 1. FIG. FIG. 3 is a block diagram showing a schematic configuration of a light emitting device of Example 2. The schematic diagram which shows the arrangement configuration of the light-emitting device of Example 2. FIG. Flowchart for explaining operation of target light sensor value information recording of embodiment 2 Flowchart for explaining the operation for adjusting the light emission intensity of the light emitting device of the second embodiment. Example 2 Initial Current Value, Target Light Sensor Value, Light Sensor Detection Value, Temperature Sensor Value The figure which shows the temperature characteristic information of Example 2 FIG. 3 is a block diagram showing a schematic configuration of a light emitting device of Example 3. The schematic diagram which shows the arrangement configuration of the light-emitting device of Example 3. Flowchart at the time of recording target light sensor value and initial sensor history information according to embodiment 3 The flowchart explaining the operation | movement at the time of the optical sensor value log | history information update of Example 3. Flowchart for explaining the operation of adjusting the light emission intensity of the light emitting device according to the third embodiment. The figure which shows the initial stage electric current value information of Example 3, and target optical sensor value information. The figure which shows the initial optical sensor value log | history information of Example 3. The figure which shows the optical sensor value log | history information after the update of Example 3. The figure which shows the detected value of the optical sensor of Example 3. The figure which shows the temperature characteristic information of Example 3

Example 1
In the first embodiment, a method for estimating the optical sensor value from the history information when the optical sensor is operating normally and the detected optical sensor values when the optical sensor fails will be described. The light emitting device of this embodiment can be applied to a backlight of an image display device such as a liquid crystal display device.

FIG. 1 is a block diagram showing a configuration of a light emitting device according to a first embodiment of the present invention. The light emitting device 100 includes a backlight unit 110 and a control unit 120. The backlight unit 110 includes a plurality of LEDs 111 and a plurality of light sensors 112. The control unit 120 also includes an optical sensor value detection unit 121, an optical sensor value complementing unit 122, an optical sensor value history recording unit 123, a backlight control unit 124, a target sensor value recording unit 125, and a backlight driving unit. 126.

  FIG. 2 is a schematic diagram illustrating the arrangement of the LEDs 111 and the optical sensors 112 of the backlight unit 110 in the first embodiment. The backlight unit 110 is divided into six control areas (illustrated by 0 to 5), which are light emitting areas that can independently control light emission. The amount of light emitted from each control area is controlled by the amount of current. In one control area, 16 LEDs whose light emission is controlled with the same amount of current are arranged in an array, and one light sensor (illustrated by A to F) that detects the luminance of each control area is provided. Located in the center of each control area.

  In the first embodiment, in order to simplify the following description, it is assumed that the light emission intensity that can be detected by one optical sensor is the intensity of light from LEDs existing in the same control area.

  Hereinafter, control of the light-emitting device 100 in Example 1 will be described with reference to flowcharts shown in FIGS. 3, 4, and 5.

First, referring to FIG. 3, a procedure for recording (storing) an optical sensor detection value when the light emitting device 100 lights a control area with a specific current amount in the optical sensor value history recording unit 123 and the target sensor value recording unit 125. Will be described.
Note that this processing is assumed to be performed, for example, in an adjustment process during production.

  In step S150, the backlight control unit 124 instructs the backlight driving unit 126 to emit all LEDs. The backlight drive unit 126 sets a predetermined same amount of current (hereinafter referred to as an initial amount of current) to all the LEDs 111 to emit light.

  In step S151, the backlight control unit 124 corrects the amount of current in each control area so that the luminance is constant and uniform based on the luminance unevenness measurement result of the backlight measured by an external measuring device (not shown). Specifically, the backlight control unit 124 acquires an average luminance distribution for each actual control area with respect to the target luminance as shown in FIG. 6 from an external measuring device, and corrects the current amount of each control area.

For example, since the luminance with respect to the target luminance in the control area 0 is 95%, the backlight control unit 124 calculates a current amount correction coefficient by the following calculation formula in order to correct this to 100%.

(100/95) ≈1.0526

At this time, assuming that the initial current amount in the control area 0 is 10,000, the backlight control unit 124 calculates a corrected current amount (hereinafter referred to as a corrected initial current amount) from the following calculation formula.

(10000 × 1.0526) = 10526

The backlight control unit 124 performs the above procedure for all control areas, and updates the calculated initial current amount after correction as the initial current amount. Next, the backlight control unit 124 causes all of the control areas to emit light with the updated initial current amount, and again measures the average luminance for each control area with respect to the target luminance using the external measuring device. When the error range becomes sufficiently small (for example, 1% or less), the backlight control unit 124 ends this step. If the error range is not sufficiently small, the backlight control unit 124 calculates the corrected initial current amount and updates the initial current amount again, and repeats until the error range becomes sufficiently small, thereby correcting the luminance unevenness of the backlight. lose. In Example 1, it is assumed that the unevenness is sufficiently reduced by one current amount correction, and the result is shown in FIG.

  In step S152, the backlight control unit 124 instructs the optical sensor value detection unit 121 to acquire the detection values of the light emission intensity by the optical sensors A to F. The optical sensor value detection unit 121 transmits an analog voltage obtained from the optical sensors A to F converted to a digital value (hereinafter, “optical sensor detection value”) to the optical sensor value complementing unit 122.

  In step S <b> 153, the backlight control unit 124 records the optical sensor detection value transmitted to the optical sensor value complementing unit 122 in the optical sensor value history recording unit 123. The optical sensor value history recording unit 123 stores optical sensor detection value history information as shown in FIG. 8. In this process, the optical sensor detection value is recorded in a table area after 0 hours from the start of use.

  In step S154, the backlight control unit 124 records the optical sensor detection value transmitted to the optical sensor value complementing unit 122 in the target sensor value recording unit 125 as a target value. The target sensor value recording unit 125 holds target light sensor value information as shown in FIG.

Next, a procedure for periodically recording the optical sensor detection value when the light emitting device 100 lights the control area with a specific current amount in the target sensor value recording unit 125 will be described with reference to FIG.
This processing is performed every time when the accumulated lighting time of the backlight elapses for a fixed time after the user starts using the liquid crystal display device equipped with the light emitting device, and when the user is not using the display device. Assumes that.

  In the first embodiment, the predetermined time is 500 hours, and the operation when the backlight lighting time has elapsed 1000 hours after the user starts using the display device will be specifically described.

  In step S160, the backlight control unit 124 instructs the backlight driving unit 126 to emit all LEDs. The backlight drive unit 126 sets an initial current amount for all the LEDs 111 to emit light.

  In step S <b> 161, the backlight control unit 124 instructs the optical sensor value detection unit 121 to acquire the detection values of the light emission intensity by the optical sensors A to F. The optical sensor value detection unit 121 transmits the optical sensor detection values obtained from the optical sensors A to F to the optical sensor value complementing unit 122.

  In step S <b> 162, the backlight control unit 124 records the optical sensor detection value transmitted to the optical sensor value complementing unit 122 in the optical sensor value history recording unit 123. In this process, the optical sensor detection value is recorded in a table area where the lighting time of the backlight is 500 hours. The history information of the optical sensor detection value at this time is shown in FIG.

Next, a procedure for causing the light emitting device 100 to bring the light sensor detection value for each control area close to the target light sensor value and making the luminance of each control area constant will be described with reference to FIG.
This processing is assumed to be performed immediately after the user starts using the liquid crystal display device equipped with the light emitting device.

  In step S170, the backlight control unit 124 instructs the backlight driving unit 126 to emit all LEDs. The backlight drive unit 126 sets an initial current amount for all the LEDs 111 to emit light.

  In step S171, the backlight control unit 124 instructs the optical sensor value detection unit 121 to acquire the detection values of the light emission intensities by the optical sensors A to F. The optical sensor value detection unit 121 transmits the optical sensor detection values obtained from the optical sensors A to F to the optical sensor value complementing unit 122.

  In step S172, the backlight control unit 124 instructs the optical sensor value complementing unit 122 to check whether there is a faulty optical sensor, and the optical sensor value complementing unit 122 determines that the optical sensor has failed. The optical sensor failure determination method determines, for example, that a failure occurs when a detection value of a certain optical sensor has a difference of 50% or more compared to a detection value of another optical sensor. The failure determination method is not limited to this example.

Hereinafter, the determination method will be specifically described. Assume that the detection value of the optical sensor can be acquired at a certain timing as shown in FIG. At this time, the failure of the optical sensor B is determined by the determination formula shown below.

| (Detection value of optical sensor B / ((detection value of optical sensor A + detection value of optical sensor C + detection value of optical sensor D + detection value of optical sensor E + detection value of optical sensor F) / 5)) -1 | ≧ 0.5

Substituting actual numbers into this formula,

| (412 / ((903 + 904 + 900 + 902 + 903) / 5))-1 |
≒ 0.54344

Since the difference is 50% or more, the optical sensor value complementing unit 122 determines that a failure has occurred.

  With the above determination method, in the example of FIG. 11, the optical sensor value complementing unit 122 determines that only the optical sensor B has failed. The failure determination method is not limited to the above-described method, and for example, a failure determination method may be used when the optical sensor detection value is equal to or less than a predetermined value.

  In step S173, the backlight control unit 124 instructs the optical sensor value complementing unit 122 to estimate a detection value when the failed optical sensor is not defective. The photosensor value complementing unit 122 estimates the detection value of the faulty photosensor using the photosensor detection value history information recorded in the photosensor value history recording unit 123.

  Hereinafter, assuming that the timing at which the sensor value is acquired in step S171 is 1000 hours of cumulative lighting of the backlight, the estimation method will be specifically described.

First, the optical sensor value complementing unit 122 acquires the optical sensor detection value history information from the optical sensor value history recording unit 123. In the first embodiment, history information as shown in FIG. 9 is recorded, and it is determined how the detection value of the normal optical sensor has changed from a certain point in the past (here, when 500 hours have elapsed). The average rate of change in the detected value of the photosensors other than the photosensor B determined to be malfunctioning (average value of the rate of change in the detected value of the normal photosensor) is calculated by the following formula: Is required.

(((Current detection value of optical sensor A / detection value of optical sensor A when 500 hours have elapsed)
+ (Current detection value of optical sensor C / detection value of optical sensor C when 500 hours have elapsed)
+ (Current detection value of optical sensor D / detection value of optical sensor D when 500 hours have elapsed)
+ (Current detection value of the optical sensor E / Detection value of the optical sensor E when 500 hours have elapsed)
+ (Current detection value of the optical sensor F / detection value of the optical sensor F when 500 hours have elapsed) / 5) -1
≒ -0.048

From the above calculation formula, it can be seen that the average detection value of the optical sensors other than the optical sensor B is reduced by about 4.8%.

  Next, the optical sensor value complementing unit 122 calculates the current optical sensor from the detected value of the average optical sensor and the detected value of the optical sensor B after 500 hours when the failed optical sensor B has moved normally. The detected value of B is estimated.

The average detection value of the non-failed optical sensor is reduced by 4.8%, and the detection value of the optical sensor B when 500 hours have elapsed is 957. Therefore, the detection value of the optical sensor B is estimated. value is

957 × (1-0.048) ≈911

Can be calculated.

  In step S174, the backlight control unit 124 acquires the target sensor value from the target sensor value recording unit 125. The backlight control unit 124 corrects the amount of current in each control area from the acquired target sensor value and the estimated optical sensor detection value.

Since the target sensor value of the control area 1 is 1005 and the estimated sensor value is 911, the current amount correction coefficient is calculated by the following calculation formula.

(1005/911) ≒ 1.1032

In addition, since the initial current amount in the control area 1 is 10,000, the corrected current amount in the control area 1 (hereinafter, the corrected current amount) is calculated by the following calculation formula.

(10000 x 1.1032) = 11032

The backlight control unit 124 sets the corrected current amount obtained in this way in the control area 1 to emit light.

  Through the above processing, the liquid crystal display device equipped with the light emitting device can estimate the light sensor detection value and emit light with uniform luminance even when time has elapsed since the sensor failed.

  In the first embodiment, an example of an estimation method using only the optical sensor detection value history information immediately before the failure has been specifically described for estimating the detection value of the failed optical sensor. When there is more history information, the detection value of the faulty optical sensor may be predicted from the prediction of the change of the detection value of the optical sensor and the change of the actual detection value of the optical sensor that has not failed.

(Example 2)
In the second embodiment, a temperature sensor that detects the temperature of each control area is arranged in the vicinity of the optical sensor, and when the optical sensor fails, the failed light is detected from the temperature sensor and the detected values of the surrounding optical sensors. A method for obtaining the estimated value of the luminance of the light emitting area corresponding to the sensor will be described.

  FIG. 10 is a block diagram showing the configuration of the light emitting device in the second embodiment of the present invention. The light emitting device 200 includes a backlight unit 210 and a control unit 220. The backlight unit 210 includes a plurality of LEDs 211, a plurality of light sensors 212, and a plurality of temperature sensors 213. In addition, the control unit 220 includes an optical sensor value detection unit 221, an optical sensor value complementing unit 222, a temperature characteristic recording unit 223, a backlight control unit 224, a target sensor value recording unit 225, and a backlight driving unit 226. The temperature sensor value detection unit 227 is provided.

  FIG. 11 is a schematic diagram illustrating the arrangement of the LED 211, the optical sensor 212, and the temperature sensor 213 of the backlight unit 210 in the second embodiment. The backlight unit 210 is divided into six control areas (shown as 0 to 5). In one control area, 16 LEDs whose emission is controlled with the same amount of current are arranged in an array, and one light sensor (shown as A to F) and one temperature sensor (a to (shown by f) is arranged near the center of each control area.

  In the second embodiment, in order to simplify the following description, it is assumed that the light emission intensity that can be detected by one optical sensor is the intensity of light from LEDs existing in the same control area.

  Hereinafter, control of the light-emitting device 200 in Example 2 will be described with reference to flowcharts shown in FIGS. 12 and 13.

First, the procedure for recording the optical sensor detection value in the target sensor value recording unit 225 when the light emitting device 200 lights the control area with a specific current amount will be described with reference to FIG.
Note that this processing is assumed to be performed, for example, in an adjustment process during production.

  Steps S250, S251, and S252 are the same as steps S150, S151, and S152 described in the first embodiment, and thus the description thereof is omitted. Note that the corrected initial current amount obtained in step S251 is shown in FIG.

  In step S253, the backlight control unit 224 instructs the temperature sensor value detection unit 227 to acquire temperature detection values from the temperature sensors a to f. The temperature sensor value detection unit 227 converts the analog voltage obtained from the temperature sensors a to f into a digital value, and further converts the digital value into a Celsius temperature (hereinafter referred to as a temperature sensor detection value) to complement the optical sensor value. To the unit 222.

  In step S254, the backlight control unit 224 records the optical sensor detection value and the temperature sensor detection value transmitted to the optical sensor value complementing unit 222 in the target sensor value recording unit 225. The target sensor value recording unit 225 holds target light sensor value information as shown in FIG.

Next, a procedure for causing the light emitting device 200 to bring the light sensor detection value for each control area close to the target light sensor value and to make the luminance of each control area constant will be described using FIG.
This processing is assumed to be performed immediately after the user starts using the liquid crystal display device equipped with the light emitting device.

  Steps S270, S271, and S272 are the same as steps S170, 171, and S172 described in the first embodiment, and thus the description thereof is omitted. Note that the detection value of the optical sensor acquired in step S271 is shown in FIG. Further, it is assumed that only the optical sensor B is determined as a failure in step S272.

  In step S273, the backlight control unit 224 instructs the temperature sensor value detection unit 227 to acquire temperature detection values from the temperature sensors a to f. The temperature sensor value detection unit 227 acquires a temperature detection value from each temperature sensor and transmits it to the optical sensor value complementing unit 222.

  In step S274, the backlight control unit 224 instructs the optical sensor value complementing unit 222 to estimate a detection value when the failed optical sensor has not failed. The optical sensor value complementing unit 222 estimates the detection value of the failed optical sensor using the temperature characteristic information recorded in the temperature characteristic recording unit 223.

Hereinafter, the estimation method will be specifically described.
First, the optical sensor value complementing unit 222 acquires temperature characteristic information of the optical sensor from the temperature characteristic recording unit 223. The temperature characteristic information is data indicating how the detection value of the optical sensor changes according to the temperature as shown in FIG. In general, an LED as a backlight light source has a feature that light emission intensity decreases when the ambient temperature rises even with the same amount of current, and the detection value of the photosensor also decreases accordingly. The temperature characteristic information shown in FIG. 15 indicates that the optical sensor when the temperature changes without changing the amount of current, assuming that the detection value of the optical sensor when the control area emits light at an ambient temperature of 25 ° C. is 100%. Indicates the rate of change of the detected value.

Next, the temperature characteristic recording unit 223 predicts the detected value of the failed optical sensor B from the detected value of the non-failed optical sensor and the temperature characteristic information. For example, when the detected value of the optical sensor and the detected value of the temperature sensor are as shown in FIG. 14D, the detected value of the failed optical sensor B can be estimated by the following calculation formula.

((Prediction of detection value of optical sensor A at reference temperature + Prediction of detection value of optical sensor C at reference temperature + Prediction of detection value of optical sensor D at reference temperature + Prediction of detection value of optical sensor E at reference temperature + Prediction of detection value of optical sensor F at reference temperature) / 5)
× (Change rate of optical sensor detection value at temperature sensor value of temperature sensor b / Change rate of optical sensor detection value at reference temperature)

Here, the prediction of the detection value of the optical sensor A at the reference temperature is obtained by converting the detection value of the optical sensor A (at the time of correction) to the detection value at the reference temperature based on the temperature characteristics.
When the reference temperature is 25 ° C and the actual value is substituted into the above formula,

((903 × (100 / 97.4) + 904 × (100 / 96.6) + 900 × (100 / 98.2) + 902 × (100 / 97.8) + 903 × (100 / 97.4))) / 5 ) X (97/100)
≒ 898

It becomes. In the above calculation formula, when there is no temperature characteristic information corresponding to the measured temperature, the change rate of the detected value of the optical sensor is obtained by linear interpolation.

  In step S275, the backlight control unit 224 acquires the target sensor value from the target sensor value recording unit 225. The backlight control unit 224 corrects the current amount in each control area from the acquired target sensor value and the estimated optical sensor detection value.

Since the target sensor value of the control area 1 is 1005 and the estimated sensor value is 898, the current amount correction coefficient is calculated by the following calculation formula.

(1005/898) ≒ 1.1192

In addition, since the initial current amount in the control area 1 is 10,000, the corrected current amount in the control area 1 (hereinafter, the corrected current amount) is calculated by the following calculation formula.

(10000 × 1.1192) = 11192

The corrected current amount thus obtained is set in the control area 1 to emit light.

  Through the above processing, the liquid crystal display device equipped with the light emitting device can estimate the detected value of the optical sensor even when the ambient temperature changes after the failure of the optical sensor, and can ensure luminance uniformity. .

(Example 3)
In the third embodiment, a method for estimating the optical sensor value from the history information when the optical sensor is operating normally, the temperature sensor, and the ambient optical sensor detection value will be described.

  FIG. 16 is a block diagram showing the configuration of the light emitting device in the third embodiment of the present invention. The light emitting device 300 includes a backlight unit 310 and a control unit 320. The backlight unit 310 includes a plurality of LEDs 311, a plurality of light sensors 312, and a plurality of temperature sensors 313. The control unit 320 includes an optical sensor value detection unit 321, an optical sensor value complementing unit 322, an optical sensor value history recording unit 323, a backlight control unit 324, a target sensor value recording unit 325, and a backlight driving unit. 326 and a temperature sensor value detector 327.

  FIG. 17 is a schematic diagram illustrating the arrangement of the LED 311, the optical sensor 312, and the temperature sensor 313 of the backlight unit 310 in the third embodiment. The backlight unit 310 is divided into six control areas (shown as 0 to 5). In one control area, 16 LEDs whose emission is controlled with the same amount of current are arranged in an array, and one light sensor (shown as A to F) and one temperature sensor (a to (shown by f) is arranged at the center of each control area.

  In the third embodiment, in order to simplify the following description, it is assumed that the light emission intensity that can be detected by one optical sensor is the intensity of light from LEDs existing in the same control area.

Hereinafter, control of the light-emitting device 300 in Example 3 will be described with reference to flowcharts shown in FIGS. 18, 19, and 20.
First, referring to FIG. 18, the light sensor detection value and the temperature sensor detection value when the light emitting device 300 lights the control area with a specific current amount are recorded in the light sensor value history recording unit 323 and the target sensor value recording unit 325. The procedure to do is demonstrated.
Note that this processing is assumed to be performed, for example, in an adjustment process during production.

  Steps S350, S351, and S352 are the same as steps S150, S151, and S152 described in the first embodiment, and thus description thereof is omitted. Note that the corrected initial current amount obtained in step S351 is shown in FIG.

Since step S353 performs the same process as step S253 described in the second embodiment, a description thereof will be omitted.
In step S354, the backlight control unit 324 records the optical sensor detection value and the temperature sensor detection value transmitted to the optical sensor value complementing unit 322 in the optical sensor value history recording unit 323. The optical sensor value history recording unit 323 holds the history information of the optical sensor detection value and the temperature sensor detection value as shown in FIG. 22, and in this process, the optical sensor detection value and the temperature sensor detection value are stored in the table area after 0 hours of use. Record the temperature sensor detection value.

  In step S <b> 355, the backlight control unit 324 records the optical sensor detection value and the temperature sensor detection value transmitted to the optical sensor value complementing unit 322 in the target sensor value recording unit 325. The target sensor value recording unit 325 holds target light sensor value information as shown in FIG.

Next, a procedure for periodically recording the optical sensor detection value when the light emitting device 300 lights the control area with a specific current amount in the target sensor value recording unit 325 will be described with reference to FIG.
This processing is performed every time when the accumulated lighting time of the backlight elapses for a fixed time after the user starts using the liquid crystal display device equipped with the light emitting device, and when the user is not using the display device. Assumes that.

  In the third embodiment, the predetermined time is 500 hours, and the operation when the backlight lighting time has elapsed 1000 hours after the user starts using the display device will be specifically described.

  Steps S360 and S361 perform the same processing as steps S160 and S161 described in the first embodiment, and thus the description thereof is omitted.

  In step S362, the backlight control unit 324 instructs the temperature sensor value detection unit 327 to detect the temperatures of the temperature sensors a to f. The temperature sensor value detection unit 327 transmits the temperature sensor detection value obtained from the temperature sensors a to f to the optical sensor value complementing unit 322.

  In step S363, the backlight control unit 324 records the optical sensor detection value and the temperature sensor detection value transmitted to the optical sensor value complementing unit 322 in the optical sensor value history recording unit 323. Here, the backlight control unit 324 records the optical sensor detection value and the temperature sensor detection value in a table area where the lighting time of the backlight is 500 hours. FIG. 23 shows history information of the optical sensor detection value and the temperature sensor detection value at this time.

Next, a procedure for causing the light emitting device 300 to bring the sensor detection value for each control area close to the target sensor value and making the luminance of each control area constant will be described using FIG.
This processing is assumed to be performed immediately after the user starts using the liquid crystal display device equipped with the light emitting device.

  Steps S370, S371, and S372 perform the same processing as steps S170, S171, and S172 described in the first embodiment, and thus description thereof is omitted. Note that FIG. 24 shows the detection value of the optical sensor acquired in step S371 and the sensor determined to be faulty in step S372.

  Since step S373 performs the same process as step S273 described in the second embodiment, description thereof is omitted.

  In step S374, the backlight control unit 324 instructs the optical sensor value complementing unit 322 to estimate the detected value of the faulty optical sensor, and the optical sensor value complementing unit 322 detects the temperature characteristic recorded in the temperature characteristic recording unit 328. Using the information, the detection value of the failed optical sensor is estimated. FIG. 25 is a diagram illustrating an example of temperature characteristic information used in the third embodiment.

  Hereinafter, assuming that the timing at which the sensor value is acquired in step S371 is 1000 hours of cumulative lighting of the backlight, the estimation method will be specifically described.

First, the optical sensor value complementing unit 322 acquires the optical sensor detection value history information from the optical sensor value history recording unit 323. In the third embodiment, history information as shown in FIG. 23 is recorded, and the optical sensor value complementing unit 322 determines how the detection value of the normal optical sensor has changed since the lapse of 500 hours. The rate of change of the average optical sensor detection value of the sensors other than the optical sensor B determined to be faulty can be obtained by the following calculation formula.

(((Prediction of the current detection value of the optical sensor A at the reference temperature / Prediction of the detection value of the optical sensor A after the elapse of 500 hours at the reference temperature))
+ (Prediction of the current detection value of the optical sensor C at the reference temperature / Prediction of the detection value of the optical sensor C when 500 hours have elapsed at the reference temperature)
+ (Prediction of current detection value of optical sensor D at reference temperature / Prediction of detection value of optical sensor D after 500 hours at reference temperature)
+ (Prediction of the current detection value of the optical sensor E at the reference temperature / Prediction of the detection value of the optical sensor E when 500 hours have elapsed at the reference temperature)
+ (Prediction of the current detection value of the optical sensor F at the reference temperature / Prediction of the detection value of the optical sensor F after the elapse of 500 hours at the reference temperature) / 5)

When the reference temperature is set to 25 ° C. and the actual measured value and the temperature change rate are substituted into the above equation,

= (((((903 * (100 / 97.4)) / (950 * (100/99))))
+ ((904 × (100 / 96.6)) / (942 × (100 / 96.6)))
+ ((900 × (100 / 98.2)) / (947 × (100 / 98.2)))
+ ((902 × (100 / 97.8)) / (949 × (100 / 97.8))))
+ ((903 × (100 / 97.4)) / (951 × (100 / 97.4)))))
/ 5)
≈ 0.955

Thus, it can be estimated that the average detection value of the optical sensors other than the optical sensor B at the reference temperature is reduced to about 95.5%. Further, since the detection value of the optical sensor B at the time when 500 hours have elapsed is 957, the detection value of the optical sensor B in consideration of the change over time can be obtained by the following calculation formula.

(Prediction of detection value of photosensor B at the time of elapse of 500 hours at the reference temperature × Decrease rate of luminance after elapse of time × Change rate of photosensor detection value at the current temperature)

When the reference temperature is 25 ° C and the actual value is substituted into the above formula,

= (957 × (100/97)) × (0.955) × (97/100)
≒ 914

It becomes.

  In step S375, the backlight control unit 324 acquires the target sensor value from the target sensor value recording unit 325. The backlight control unit 324 corrects the amount of current in each control area from the acquired target sensor value and the estimated optical sensor detection value.

Since the target sensor value of the control area 1 is 1005 and the estimated sensor value is 914,
The current amount correction coefficient is calculated by the following formula.

(1005/914) ≈1.0996

Further, since the initial current amount is 10,000, the corrected current amount in the control area 1 (hereinafter, the corrected current amount) is calculated by the following calculation formula.

(10000 × 1.0996) = 10996

The corrected current amount thus obtained is set in the control area 1 to emit light.

  Through the above processing, the liquid crystal display device equipped with the light emitting device can estimate the photosensor detection value even when time has elapsed since the photosensor failure and the temperature has changed, and the luminance uniformity can be improved. Can be secured.

  In the third embodiment, an example of an estimation method using only the optical sensor detection value history information immediately before the failure has been specifically described for estimating the detection value of the failed optical sensor. When there is more history information, the detection value of the faulty optical sensor may be predicted from the prediction of the change of the detection value of the optical sensor and the change of the actual detection value of the optical sensor that has not failed.

DESCRIPTION OF SYMBOLS 100 Light-emitting device, 110 Backlight unit, 120 Control unit, 112 Optical sensor, 124 Backlight control part, 125 Target sensor value recording part

Claims (23)

A light emitting means comprising a plurality of light emitting regions capable of independently controlling light emission;
Control means for controlling the light emission amount of each light emitting region;
A plurality of luminance detecting means for detecting the luminance of each light emitting region;
Storage means for storing a target value of luminance of each light emitting area;
Correction means for correcting the light emission amount of each light emitting region so that the brightness detected by each brightness detection means approaches the target value;
With
In the case where there is a malfunction among the plurality of brightness detection means, the correction means emits light corresponding to the malfunctioning brightness detection means based on the brightness detected by the brightness detection means not malfunctioning. A light emitting device characterized by estimating a luminance of a region and correcting a light emission amount of a light emitting region corresponding to a malfunctioning luminance detecting unit based on the estimated luminance. The storage means stores a history of brightness detected by the brightness detection means,
The light-emitting device according to claim 1, wherein the correction unit estimates the luminance of the light-emitting area corresponding to the malfunctioning luminance detection unit based on the luminance history detected by the luminance detection unit that is not malfunctioning.   The correction means calculates the rate of change in luminance from the luminance detected at a certain time in the past by the non-failed luminance detection means and the luminance detected by the correction means by the non-failed luminance detection means during correction. The luminance obtained by multiplying the luminance detected at a certain time in the past by the rate of change by the luminance detecting unit having a failure and the estimated value of the luminance of the light emitting area corresponding to the luminance detecting unit having a failure The light emitting device according to claim 2.   When there are a plurality of non-failed brightness detection means, the correction means obtains the rate of change for each of the brightness detection means, and the brightness detected at the certain time in the past by the failed brightness detection means 4. The light emitting device according to claim 3, wherein the luminance obtained by multiplying the average value of the change rates is an estimated value of the luminance of the light emitting region corresponding to the malfunctioning luminance detecting means.   The said memory | storage means memorize | stores the said log | history by memorize | storing the brightness | luminance detected by each said brightness | luminance detection means when making each said light emission area light-emit with a predetermined electric current amount for every fixed time. The light-emitting device of any one of Claims. A plurality of temperature detecting means for detecting the temperature of each light emitting region;
The storage means stores information on the temperature characteristics of the luminance of the light emitting area,
The correcting means determines whether or not the malfunctioning brightness detection means is based on the brightness detected by the malfunctioning brightness detection means, the temperature detected by the temperature detection means, and the temperature characteristics of the light emitting area. The light-emitting device according to claim 1, wherein the luminance of the corresponding light-emitting area is estimated.   The correction unit converts the luminance detected by the non-failed luminance detection unit into luminance at a predetermined reference temperature based on the temperature characteristic, and the converted luminance is broken based on the temperature characteristic. The light-emitting device according to claim 6, wherein the light-emitting device is converted into luminance at a temperature of the light-emitting area corresponding to the luminance detection means, and the converted luminance is used as an estimated value of the luminance of the light-emitting area corresponding to the malfunctioning luminance detection means. . When there are a plurality of non-failed luminance detecting means, the correcting means converts the luminance detected by each of the luminance detecting means into luminance at a predetermined reference temperature based on the temperature characteristics, and the converted luminance Is converted into the luminance at the temperature of the light emitting region corresponding to the malfunctioning luminance detecting means based on the temperature characteristic, and the converted luminance is calculated for the light emitting area corresponding to the malfunctioning luminance detecting means. The light emitting device according to claim 7, wherein the luminance is estimated. A plurality of temperature detecting means for detecting the temperature of each light emitting region;
The storage means stores a history of brightness detected by the brightness detection means and information on temperature characteristics of brightness of the light emitting area,
The correcting means detects the malfunctioning brightness based on the history of brightness detected by the malfunctioning brightness detecting means, the temperature detected by the temperature detecting means, and the temperature characteristics of the light emitting area. The light-emitting device according to claim 1, wherein the luminance of the light-emitting area corresponding to the means is estimated. The correction means includes
The luminance detected at a certain time in the past by the non-failed luminance detecting means is converted into the luminance at a predetermined reference temperature, and the luminance detected at the time of correction by the correcting means by the non-failed luminance detecting means. From the brightness converted to the brightness at the reference temperature, find the rate of change in brightness,
The luminance obtained by multiplying the luminance detected at a certain time in the past by the malfunctioning luminance detection means into the luminance at the reference temperature and the rate of change was detected at the time of correction by the correction means. The light-emitting device according to claim 9, wherein the light-emitting device is converted into luminance at temperature, and the converted luminance is used as an estimated value of the luminance of the light-emitting area corresponding to the malfunctioning luminance detection unit.   When there are a plurality of non-failed brightness detecting means, the correction means obtains the rate of change for each of the brightness detecting means, and uses the brightness detected at a certain past time by the failed brightness detecting means as a reference. The brightness obtained by multiplying the brightness converted into the brightness at the temperature by the average value of the change rate is converted into the brightness at the temperature detected at the time of correction by the correction means, and the converted brightness is broken. The light emitting device according to claim 10, wherein the luminance is an estimated value of a light emitting area corresponding to the luminance detecting means. A method for controlling a light emitting device, comprising: a light emitting unit composed of a plurality of light emitting regions capable of independently controlling light emission; and a plurality of luminance detecting units for detecting the luminance of each of the light emitting regions. A control process for controlling
Detecting the luminance of each light emitting region by a corresponding luminance detecting means;
Obtaining a target value of luminance of each light emitting area from a storage means;
A correction step of correcting the light emission amount of each light emitting region so that the luminance detected by each luminance detection means approaches the target value;
Have
In the correction step, when there is a malfunction among the plurality of brightness detection means, the light emission corresponding to the malfunctioned brightness detection means is based on the brightness detected by the brightness detection means that is not malfunctioning. A method for controlling a light emitting device, comprising: estimating a luminance of a region, and correcting a light emission amount of a light emitting region corresponding to a malfunctioning luminance detecting unit based on the estimated luminance. The storage means stores a history of brightness detected by the brightness detection means,
13. The light emitting device control according to claim 12, wherein in the correction step, the luminance of the light emitting area corresponding to the malfunctioning luminance detecting means is estimated based on the history of the luminance detected by the malfunctioning luminance detecting means. Method.   In the correction step, the luminance change rate is calculated from the luminance detected at a certain time in the past by the non-failed luminance detection means and the luminance detected at the time of correction by the correction step by the non-failed luminance detection means. The luminance obtained by multiplying the luminance detected at a certain time in the past by the rate of change by the luminance detecting unit having a failure and the estimated value of the luminance of the light emitting area corresponding to the luminance detecting unit having a failure The method for controlling the light emitting device according to claim 13. In the correction step, when there are a plurality of non-failed luminance detecting means, the change rate is obtained for each of the luminance detecting means, and the luminance detected at a certain time in the past by the failed luminance detecting means 15. The method for controlling a light emitting device according to claim 14, wherein the luminance obtained by multiplying the average value of the change rates is an estimated value of the luminance of the light emitting region corresponding to the malfunctioning luminance detecting means.   The said memory | storage means memorize | stores the said log | history by memorize | storing the brightness | luminance detected by each said brightness | luminance detection means when making each said light emission area light-emit with predetermined current amount every fixed time, The memory | storage is memorize | stored. The control method of the light-emitting device of any one of Claims 1. The light emitting device further includes a plurality of temperature detecting means for detecting the temperature of each light emitting region,
The method for controlling the light emitting device further includes a step of detecting the temperature of each light emitting region by a corresponding temperature detecting means,
The storage means stores information on the temperature characteristics of the luminance of the light emitting area,
In the correction step, the malfunction detection unit detects the malfunction detected by the malfunction detection unit based on the brightness detected by the malfunction detection unit, the temperature detected by the temperature detection unit, and the temperature characteristics of the light emitting region. The method for controlling a light emitting device according to claim 12, wherein the luminance of the corresponding light emitting region is estimated.   In the correction step, the luminance detected by the non-failed luminance detecting means is converted into luminance at a predetermined reference temperature based on the temperature characteristic, and the converted luminance is broken based on the temperature characteristic. 18. The light-emitting device according to claim 17, wherein the light-emitting device is converted into luminance at a temperature of the light-emitting area corresponding to the luminance detection means, and the converted luminance is an estimated value of the luminance of the light-emitting area corresponding to the malfunctioning luminance detection means. Control method.   In the correction step, when there are a plurality of non-failed luminance detecting means, the luminance detected by each of the luminance detecting means is converted into luminance at a predetermined reference temperature based on the temperature characteristics, and the converted luminance is Is converted into the luminance at the temperature of the light emitting region corresponding to the malfunctioning luminance detecting means based on the temperature characteristic, and the converted luminance is calculated for the light emitting area corresponding to the malfunctioning luminance detecting means. The method for controlling a light emitting device according to claim 18, wherein the brightness is estimated. The light emitting device further includes a plurality of temperature detecting means for detecting the temperature of each light emitting region,
The method for controlling the light emitting device further includes a step of detecting the temperature of each light emitting region by a corresponding temperature detecting means,
The storage means stores a history of brightness detected by the brightness detection means and information on temperature characteristics of brightness of the light emitting area,
In the correction step, the malfunction detection is performed based on the history of the brightness detected by the malfunction detection means, the temperature detected by the temperature detection means, and the temperature characteristics of the light emitting area. The method of controlling a light emitting device according to claim 12, wherein the luminance of the light emitting area corresponding to the means is estimated. In the correction step,
The brightness detected at a certain time in the past by the brightness detecting means that has not failed is converted into the brightness at a predetermined reference temperature, and the brightness detected at the time of correction by the correcting step by the brightness detecting means that has not failed. From the brightness converted to the brightness at the reference temperature, find the rate of change in brightness,
The luminance obtained by multiplying the luminance detected at a certain time in the past by the luminance detecting means having failed to the luminance at the reference temperature by multiplying by the change rate was detected at the time of correction by the correction step. 21. The method of controlling a light emitting device according to claim 20, wherein the method is converted into luminance at temperature, and the converted luminance is used as an estimated value of luminance of a light emitting region corresponding to a malfunctioning luminance detecting means. In the correction step, when there are a plurality of non-failed brightness detecting means, the rate of change is obtained for each of the brightness detecting means, and the brightness detected at a certain time in the past by the failed brightness detecting means is used as a reference. The brightness obtained by multiplying the brightness converted into the brightness at the temperature by the average value of the rate of change is converted into the brightness at the temperature detected at the time of correction by the correction step, and the converted brightness is broken. 22. The method for controlling a light emitting device according to claim 21, wherein the luminance is an estimated value of a light emitting area corresponding to the luminance detecting means.   An image display device comprising the light emitting device according to claim 1 as a backlight.

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