JP6289687B2 - LIGHT SOURCE DEVICE, LIGHT SOURCE DEVICE CONTROL METHOD, AND DISPLAY DEVICE - Google Patents

Description

The present invention relates to a light source device , a control method for the light source device , and a display device .

Some color image display devices include a color liquid crystal panel having a color filter and a light source device (backlight device) that emits white light to the back surface of the color liquid crystal panel.
Conventionally, a fluorescent lamp such as a cold cathode fluorescent lamp (CCFL) has been mainly used as a light source of a light source device. However, in recent years, light emitting diodes (LEDs) that are excellent in terms of power consumption, lifetime, color reproducibility, and environmental load have come to be used as light sources of light source devices.

  A light source device (LED backlight device) using LEDs as a light source generally has a large number of LEDs. Patent Document 1 discloses an LED backlight device having a plurality of light emitting units each having one or more LEDs. Patent Document 1 discloses that the luminance of a light emitting unit is controlled for each light emitting unit. By reducing the light emission luminance of the light emitting unit that irradiates light to a region where a dark image is displayed in the screen of the color image display device, power consumption is reduced and image contrast is improved. Such luminance control for each light emitting unit in accordance with image characteristics is referred to as local dimming control.

The light source device has a problem that the light emission luminance from the light emitting unit changes. The change in light emission luminance is caused by, for example, a change in light emission characteristics of the light source due to a temperature change, aged deterioration of the light source, and the like. In a light-emitting device having a plurality of light-emitting portions, variations in the light emission luminance (brightness unevenness) of the light-emitting portions occur due to variations in the temperature and the degree of aging of the light-emitting portions.
As a technique for reducing such a change in light emission brightness and uneven brightness, a technique for adjusting the light emission brightness of a light emitting unit using an optical sensor is known. Specifically, among the light emitted from the light source device, a light sensor that detects reflected light that is reflected by the optical sheet (optical member) of the light source device and returned to the light emitting unit side is provided. A method of adjusting the light emission luminance of the light emitting unit based on the above is known. In a light-emitting device having a plurality of light-emitting units, each light-emitting unit is turned on in turn, and the reflected light is detected by an optical sensor for each light-emitting unit, and the light emission luminance is adjusted. Such a technique is disclosed in Patent Document 2, for example.

JP 2001-142409 A JP 2011-27941 A

  However, the luminance distribution on the light emitting portion side surface of the optical sheet when one light emitting portion is turned on changes when the optical sheet bends. In the conventional technique, such a change is not taken into consideration, and the detection value of the optical sensor greatly fluctuates due to the deflection of the optical sheet. As a result, in the conventional technique, it is impossible to adjust the light emission luminance of the light emitting unit with high accuracy.

The present invention provides a light source device and a light source capable of obtaining a detection value with small fluctuation due to the deflection of the optical sheet as a detection value of reflected light from the optical sheet, and thus adjusting the light emission luminance of the light emitting unit with high accuracy. An object is to provide a device control method and a display device .

The first aspect of the present invention is:
A plurality of light emitting units;
An optical sheet that reflects part of the light from each of the plurality of light emitting units;
A plurality of detection units for detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on,
Adjusting means for adjusting the light emission luminance of the target light emitting unit based on the detection value of the detecting unit selected from the plurality of detecting units;
Have
The optical sheet includes a first portion in which luminance on the surface of the optical sheet when the light emitting unit of the target is turned on is substantially constant without depending on a deflection amount of the optical sheet, and light emission of the target There is a second part in which the brightness on the surface of the optical sheet when the part is lit changes depending on the amount of deflection of the optical sheet,
The adjustment unit is a light source device that selects a detection unit provided at a position corresponding to the first portion .

The second aspect of the present invention is:
A plurality of light emitting units;
An optical sheet that reflects part of the light from each of the plurality of light emitting units;
A plurality of detection units for detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on,
Adjusting means for adjusting the light emission luminance of the target light emitting unit based on the detection value of the detecting unit selected from the plurality of detecting units;
Have
When the target light emitting unit is turned on, the plurality of detection units are provided at positions where an error of a detection value due to the deflection of the optical sheet is not more than a predetermined value without depending on the deflection amount of the optical sheet. And a second detection unit provided at a position where an error of a detection value due to the deflection of the optical sheet is larger than the predetermined value depending on the deflection amount of the optical sheet. Including
The adjustment unit is a light source device that selects the first detection unit .
The third aspect of the present invention is:
A plurality of light emitting units;
An optical sheet that reflects part of the light from each of the plurality of light emitting units;
A plurality of detection units for detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on,
Adjusting means for adjusting the light emission luminance of the target light emitting unit based on the detection value of the detecting unit selected from the plurality of detecting units;
Have
The plurality of detection units include a first detection unit provided at a position where a detection value when the light emitting unit of the target is turned on is substantially constant without depending on a deflection amount of the optical sheet, and the target And a second detection unit provided at a position where a detection value when the light emitting unit is turned on varies depending on the amount of deflection of the optical sheet,
The adjustment unit is a light source device that selects the first detection unit .

The fourth aspect of the present invention is:
A plurality of light emitting units, an optical sheet that reflects a part of the light from each of the plurality of light emitting units, and a plurality that detects reflected light reflected by the optical sheet when the target light emitting unit is turned on. A light source device control method comprising:
A lighting step of lighting the plurality of light emitting units one by one;
A detection step of detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on by the lighting step, by a detection unit selected from the plurality of detection units;
An adjustment step of adjusting the light emission luminance of the target light emitting unit based on the detection value of the detection unit selected in the detection step;
Have
The optical sheet includes a first portion in which luminance on the surface of the optical sheet when the light emitting unit of the target is turned on is substantially constant without depending on a deflection amount of the optical sheet, and light emission of the target There is a second part in which the brightness on the surface of the optical sheet when the part is lit changes depending on the amount of deflection of the optical sheet,
In the detection step, a detection unit provided at a position corresponding to the first portion is selected.

According to a fifth aspect of the present invention,
A plurality of light emitting units, an optical sheet that reflects a part of the light from each of the plurality of light emitting units, and a plurality that detects reflected light reflected by the optical sheet when the target light emitting unit is turned on. A light source device control method comprising:
A lighting step of lighting the plurality of light emitting units one by one;
A detection step of detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on by the lighting step, by a detection unit selected from the plurality of detection units;
An adjustment step of adjusting the light emission luminance of the target light emitting unit based on the detection value of the detection unit selected in the detection step;
Have
When the target light emitting unit is turned on, the plurality of detection units are provided at positions where an error of a detection value due to the deflection of the optical sheet is not more than a predetermined value without depending on the deflection amount of the optical sheet. And a second detection unit provided at a position where an error of a detection value due to the deflection of the optical sheet is larger than the predetermined value depending on the deflection amount of the optical sheet. Including
In the detection step, the first detection unit is selected.
The sixth aspect of the present invention is:
A plurality of light emitting units, an optical sheet that reflects a part of the light from each of the plurality of light emitting units, and a plurality that detects reflected light reflected by the optical sheet when the target light emitting unit is turned on. A light source device control method comprising:
A lighting step of lighting the plurality of light emitting units one by one;
A detection step of detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on by the lighting step, by a detection unit selected from the plurality of detection units;
An adjustment step of adjusting the light emission luminance of the target light emitting unit based on the detection value of the detection unit selected in the detection step;
Have
The plurality of detection units include a first detection unit provided at a position where a detection value when the light emitting unit of the target is turned on is substantially constant without depending on a deflection amount of the optical sheet, and the target And a second detection unit provided at a position where a detection value when the light emitting unit is turned on varies depending on the amount of deflection of the optical sheet,
In the detection step, the first detection unit is selected.

  According to the present invention, as a detection value of reflected light from the optical sheet, a detection value with a small fluctuation due to the deflection of the optical sheet can be obtained, and as a result, the light emission luminance of the light emitting unit can be adjusted with high accuracy.

The figure which shows an example of the light source device which concerns on Example 1. FIG. The figure which shows an example of the light source device which concerns on Example 1. FIG. 1 is a block diagram illustrating an example of a light source device according to a first embodiment. The figure which shows an example of the correspondence table which concerns on Example 1. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 1, and the optical sensor for adjustment. The figure which shows an example of the brightness | luminance change by the structure and deflection of the light source device which concerns on Example 1. The figure which shows an example of the light emission luminance distribution of a light emission part The figure which shows an example of the bending of an optical sheet The figure which shows an example of the relationship between the variation | change_quantity of the brightness | luminance by bending of an optical sheet, and Rd The figure which shows an example of the relationship between the directivity of the light from a light emission part, and a zero crossing point The figure which shows an example of the correspondence table which concerns on Example 1. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 1, and the optical sensor for adjustment. The figure which shows an example of the light source board | substrate which concerns on Example 1. FIG. The figure which shows an example of the light emission part which concerns on Example 2. FIG. The figure which shows an example of the relationship between the variation | change_quantity of the brightness | luminance by bending of an optical sheet, and Rd The figure which shows an example of the positional relationship of the light emission part which concerns on Example 2, and the optical sensor for adjustment. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 2, and the optical sensor for adjustment. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 2, and the optical sensor for adjustment. The figure which shows an example of the light source device which concerns on Example 3. FIG. The figure which shows an example of the correspondence table which concerns on Example 3. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 3, and the optical sensor for adjustment. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 3, and the optical sensor for adjustment. The figure which shows an example of the relationship between the variation | change_quantity of the brightness | luminance by bending of an optical sheet, and Rd The figure which shows an example of the error which concerns on Example 3. FIG. The figure which shows an example of the correspondence table which concerns on Example 3. The figure which shows an example of the error which concerns on Example 3. FIG. The figure which shows an example of the light source device which concerns on Example 3. FIG. The figure which shows an example of the correspondence table which concerns on Example 3. The figure which shows an example of the correspondence table which concerns on Example 3. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 3, and the optical sensor for adjustment. The figure which shows an example of the light source device which concerns on Example 3. FIG. The figure which shows an example of the correspondence table which concerns on Example 3. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 3, and the optical sensor for adjustment. The figure which shows an example of the positional relationship of the light emission part which concerns on Example 3, and the optical sensor for adjustment. The figure which shows an example of the relationship between the variation | change_quantity of the brightness | luminance by bending of an optical sheet, and Rd

<Example 1>
Hereinafter, a light source device and a control method thereof according to Embodiment 1 of the present invention will be described. In this embodiment, an example in which the light source device is a backlight device used in a color image display device will be described, but the light source device is not limited to the backlight device used in the display device. The light source device may be, for example, a lighting device such as a street lamp or indoor lighting.

FIG. 1A is a schematic diagram illustrating an example of a configuration of a color image display apparatus according to the present embodiment. The color image display device includes a backlight device and a color liquid crystal panel 105. The backlight device includes a light source substrate 101, a diffuser plate 102, a condensing sheet 103, a reflective polarizing film 104, and the like.
The light source substrate 101 emits light (white light) applied to the back surface of the color liquid crystal panel 105. The light source substrate 101 is provided with a plurality of light sources. As the light source, a light emitting diode (LED), a cold cathode tube, an organic EL element, or the like can be used.
The diffuser plate 102, the light condensing sheet 103, and the reflective polarizing film 104 are arranged in parallel with the light source substrate, and optically change the light from the light source substrate 101 (specifically, a light emitting unit described later).
Specifically, the diffusion plate 102 causes the light source substrate 101 to function as a surface light source by diffusing light from the plurality of light sources (LED chips in this embodiment).
The condensing sheet 103 diffuses the diffuser 102 and condenses white light incident at various incident angles in the front direction (color liquid crystal panel 105 side), thereby improving the front luminance (front luminance). Let
The reflective polarizing film 104 improves the front luminance by efficiently polarizing incident white light.
The diffuser plate 102, the light collecting sheet 103, and the reflective polarizing film 104 are used in an overlapping manner. Hereinafter, these optical members are collectively referred to as an optical sheet 106. The optical sheet 106 may include a member other than the optical member described above, or may not include at least one of the optical members described above. Further, the optical sheet 106 and the color liquid crystal panel 105 may be integrally formed.
Each member of the optical sheet 106 is made of a thin resin of about several hundred μm to several mm. Therefore, the optical sheet 106 is likely to change its shape (deflection). For example, a deflection of about several mm can occur in the thickness direction. Specifically, the amount of deflection depends on the size of the optical sheet, and is about 0.1 to 0.3% of the length of the long side of the optical sheet (about 1 to 3 mm when the length of the long side is 1000 mm). Deflection can occur. Deflection is caused by various factors such as thermal expansion, static electricity, aging, and gravity. For example, it is conceivable that a maximum deflection of about 1 mm occurs due to thermal expansion. When the optical sheet is substantially parallel to the ground, it is conceivable that a deflection of about 2 to 3 mm occurs due to gravity. As described above, since the deflection is caused by various factors, it is difficult to accurately predict the deflection of the optical sheet 106 and to prevent the deflection itself.
The color liquid crystal panel 105 includes a plurality of pixels including an R sub-pixel that transmits red light, a G sub-pixel that transmits green light, and a B sub-pixel that transmits blue light. A color image is displayed by controlling the luminance of each sub-pixel.
The backlight device having the configuration described above (the configuration shown in FIG. 1A) is generally called a direct type backlight device.

FIG. 1B is a schematic diagram illustrating an example of the configuration of the light source substrate 101.
The light source substrate 101 has a plurality of light emitting units.
In the example of FIG. 1B, the light source substrate 101 includes a total of four LED substrates 110 of 2 rows × 2 columns arranged in a matrix. In this embodiment, the light source substrate 101 has a plurality of LED substrates, but the light source substrate 101 may have one LED substrate. For example, the four LED substrates in FIG. 1B may be one LED substrate.
Each LED substrate 110 has a total of eight light emitting portions 111 of 2 rows × 4 columns. That is, the light source substrate 101 has a total of 32 light emitting units 111 of 4 rows × 8 columns.
Each light emitting unit 111 is provided with one light source (LED chip 112), and the light emission luminance of each light emitting unit 111 can be individually controlled. As the LED chip 112, for example, a white LED that emits white light can be used. As the LED chip 112, white light can be obtained by using a plurality of LEDs having different colors of emitted light (for example, a red LED emitting red light, a green LED emitting green light, a blue LED emitting blue light, etc.). A configured chip may be used.
The LED substrate 110 is provided with an optical sensor 113 (detection unit) that detects light and outputs a detection value. A part of the light from the light emitting unit 111 is reflected by the optical sheet and returned to the light emitting unit side. The optical sensor 113 detects the reflected light reflected by the optical sheet 106 and returned to the light emitting unit side. The light emission luminance of the light emitting unit 111 can be predicted from the luminance of the reflected light. In this embodiment, a plurality of photosensors are provided at different positions. In the example of FIG. 1B, four light sensors 113 are provided for one LED substrate 110. Specifically, for each of the two light emitting units 111 arranged in the column direction of the LED substrate 110, the optical sensor 113 is provided between the two light emitting units 111. As the optical sensor 113, a sensor that outputs luminance as a detection value, such as a photodiode or a phototransistor, can be used. Further, a color sensor that outputs a color change in addition to the luminance may be used as the optical sensor 113.

FIG. 2A is a schematic diagram illustrating an example of the arrangement of the LED substrate 110, the light emitting unit 111, and the optical sensor 113 when viewed from the front direction (color liquid crystal panel 105 side). The LED board 110 (1,1) is adjacent to the right side of the LED board 110 (1,1) disposed at the upper left corner, and the LED board 110 (2) is below the LED board 110 (1,1). , 1) are adjacent. The LED substrate 110 (2, 2) is adjacent to the right side of the LED substrate 110 (2, 1).
The LED substrate 110 (X, Y) (X, Y = 1 or 2) has eight light emitting portions 111 (X, Y, Z1) (Z1 = 1 to 8). For example, the LED substrate 110 (1, 1) includes the light emitting unit 111 (1, 1, 1), the light emitting unit 111 (1, 1, 2), the light emitting unit 111 (1, 1, 3), and the light emitting unit 111 (1). , 1, 4), light emitting unit 111 (1, 1, 5), light emitting unit 111 (1, 1, 6), light emitting unit 111 (1, 1, 7), and light emitting unit 111 (1, 1, 8). Have Z1 is a value indicating the position of the light emitting unit 111. Positions Z1 of the four light emitting units in the first row of the eight light emitting units 111 (X, Y, Z1) are 1, 2, 3, 4 in order from the left end, and the four light emitting units in the second row have four positions. The position Z1 is 5, 6, 7, and 8 in order from the left end.
The LED substrate 110 (X, Y) is provided with four optical sensors 113 (X, Y, Z2) (Z2 = 1 to 4). For example, the LED substrate 110 (1, 1) includes an optical sensor 113 (1, 1, 1), an optical sensor 113 (1, 1, 2), an optical sensor 113 (1, 1, 3), and an optical sensor 113 ( 1, 1, 4). Z2 is a value indicating the position of the optical sensor 113, and is 1, 2, 3, 4 in order from the left end.

FIG. 2B is a cross-sectional view (a cross-sectional view obtained by a plane perpendicular to the screen) showing an example of the arrangement of the LED substrate 110 and the optical sheet 106.
One LED chip 112 is provided in each light emitting portion 111 of the LED substrate 110. Each LED chip 112 is arranged at equal intervals. An interval between the LED chips 112 is referred to as an LED pitch 131. The LED substrate 110 is disposed in parallel with the optical sheet 106. A distance between the LED substrate 110 (light emitting unit 111) and the optical sheet 106 is referred to as a diffusion distance 130. In the backlight device using the LED chip 112 having general directivity, each member is arranged so that the diffusion distance 130 is equal to or longer than the LED pitch 131, thereby allowing the optical sheet 106 to pass through. The brightness unevenness of the light can be sufficiently reduced. In this embodiment, it is assumed that the LED pitch 131 and the diffusion distance 130 are equal.

FIG. 3 is a block diagram illustrating an example of the configuration of the backlight device.
Since the four LED boards 110 have the same configuration, the LED board 110 (1, 1) will be described as an example. The LED substrate 110 (1, 1) includes light emitting portions 111 (1, 1, 1) to 111 (1, 1, 8). The light emitting units 111 (1, 1, 1) to 111 (1, 1, 8) are driven by LED drivers 120 (1, 1, 1) to 120 (1, 1, 8), respectively.
In the present embodiment, light emission luminance adjustment processing is performed to reduce luminance unevenness caused by variations in the temperature between the light emitting units 111 and the degree of aging degradation at regular or specific timings. All the light emitting units 111 are turned on during normal operation, but in the light emission luminance adjustment processing, the plurality of light emitting units 111 are turned on one by one in a predetermined order, and the reflected light is detected using the optical sensor 113. Then, the light emission luminance of the light emitting unit 111 is adjusted based on the detection value of the optical sensor 113.

FIG. 3 shows a lighting state when obtaining a detection value used for adjusting the light emission luminance of the light emitting unit 111 (1, 1, 1). In FIG. 3, the light emitting units 111 (1, 1, 1) are turned on, and the other light emitting units 111 are turned off. Most of the light 121 (1, 1, 1) emitted from the light emitting unit 111 (1, 1, 1) is incident on the color liquid crystal panel 105 (not shown in FIG. 3). However, a part of the light is returned as reflected light from the optical sheet 106 (not shown in FIG. 3) to the light emitting unit side and enters each optical sensor 113. Each optical sensor 113 outputs an analog value 122 (detection value) representing the luminance according to the luminance of the detected reflected light. The A / D converter 123 outputs the optical sensor 113 (1, 2, 1) previously associated with the light emitting unit 111 (1, 1, 1) among the analog values 122 output by the respective optical sensors 113. The analog value 122 (1, 2, 1) is selected. Then, the A / D converter 123 performs analog-digital conversion of the selected analog value into a digital value, and outputs the digital value 124 to the microcomputer 125. The optical sensor 113 previously associated with the light emitting unit 111 is used to adjust the light emission luminance of the light emitting unit 111. Therefore, this optical sensor is hereinafter referred to as an adjustment optical sensor.
The luminance distribution on the light emitting part side surface of the optical sheet when one light emitting part is turned on changes when the optical sheet bends (the light emitting part side surface of the optical sheet is described as the back surface). In this embodiment, since the optical sensor 113 (1, 2, 1) is used when adjusting the light emission luminance of the light emitting unit 111 (1, 1, 1), a detection value with small fluctuation due to the deflection of the optical sheet is obtained. be able to. As a result, the light emission luminance of the light emitting unit can be adjusted with high accuracy. The reason why such an effect can be obtained will be described in detail later.
Similar processing is performed for the other light emitting units 111. That is, the reflected light is detected by each optical sensor 113 with only the light emitting unit 111 to be processed turned on. Then, in the A / D converter 123 whose luminance is to be adjusted, the analog value 122 of the optical sensor 113 previously associated with the light emitting unit 111 whose luminance is to be adjusted is converted into a digital value 124, and the digital value 124 is obtained. It is output to the microcomputer 125. Therefore, the A / D converter 123 outputs all 32 detection values (detection values of the optical sensor; digital value 124) to the microcomputer 125.

  The microcomputer 125 adjusts the light emission luminance of the light emitting unit 111 based on the detection value (specifically, the digital value 124) of the optical sensor 113. In this embodiment, the microcomputer 125 adjusts the light emission luminance of each light emitting unit based on the detection value of the adjustment optical sensor. Specifically, the microcomputer 125 holds the luminance target value (target value of the detection value) of each light emitting unit 111 determined at the time of manufacturing inspection of the color image display device in the nonvolatile memory 126. For each light emitting unit 111, the microcomputer 125 compares the detection value of the optical sensor 113 associated with the light emitting unit 111 with the target value. Then, the microcomputer 125 adjusts the light emission luminance for each light emitting unit 111 so that the detected value matches the target value according to the comparison result. The light emission luminance is adjusted by adjusting an LED driver control signal 127 output from the microcomputer 125 to the LED driver 120, for example. The LED driver 120 drives the light emitting unit 111 according to the LED driver control signal. The LED driver control signal represents, for example, the pulse width of a pulse signal (current or voltage pulse signal) applied to the light emitting unit 111. In that case, the light emission luminance of the light emitting unit 111 is PWM controlled by adjusting the LED driver control signal. The LED driver control signal is not limited to this. For example, the LED driver control signal may be a peak value of a pulse signal applied to the light emitting unit 111, or may be both a pulse width and a peak value. By adjusting the light emission luminance of each light emitting unit 111 so that the detected value becomes the target value, the luminance unevenness of the entire backlight device can be suppressed.

FIG. 4 is a correspondence table showing an example of a processing order of the plurality of light emitting units 111 and a correspondence relationship between the light emitting units 111 and the adjustment optical sensors. The above-described processing (processing for obtaining a detection value and outputting it to the microcomputer 125) is performed 32 times, the same as the number of the light emitting units 111.
In the first process, the light emitting unit 111 (1, 1, 1) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (1, 2, 1) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (1, 2, 1) is output to the microcomputer 125.
FIG. 5A is a schematic diagram showing a positional relationship between the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 2, 1) when viewed from the front direction (color liquid crystal panel 105 side). It is. In this embodiment, when adjusting the light emission luminance of the light emitting unit 111 (1, 1, 1), not the light sensor 113 closest to the light emitting unit 111 (1, 1, 1) but the light emitting unit 111 (1, 1). , 1), the optical sensor 113 (1, 2, 1) located at a relatively far position is used. Since the vertical distance 140 is 0.5 times the LED pitch 131 and the horizontal distance 141 is 4 times the LED pitch 131, the light emission center of the light emitting unit 111 (1, 1, 1) and the light are calculated from the three-square theorem. It can be seen that the distance to the sensor 113 (1, 2, 1) is 4.03 times the LED pitch 131. In the present embodiment, since the LED pitch 131 and the diffusion distance 130 are equivalent, the distance between the light emission center of the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 2, 1) is It can also be seen that the diffusion distance is 4.03 times.

As shown in FIG. 4, in the second process, the light emitting units 111 (1, 1, 2) are turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (1, 2, 2) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (1, 2, 2) is output to the microcomputer 125.
FIG. 5B is a schematic diagram showing the positional relationship between the light emitting units 111 (1, 1, 2) and the optical sensors 113 (1, 2, 2) when viewed from the front direction (color liquid crystal panel 105 side). It is. Similar to the first processing, the distance between the light emission center of the light emitting unit 111 (1, 1, 2) and the optical sensor 113 (1, 2, 2) is 4.03 times the diffusion distance 130.

The third and subsequent processes are similarly performed in the order shown in the correspondence table of FIG. In the third and subsequent processes, the distance between the light emitting unit 111 to be processed and the adjustment optical sensor is 4.03 times the diffusion distance 130.
In the following description, the ratio of the distance between the light emission center of the light emitting unit 111 and the optical sensor 113 with respect to the diffusion distance 130 is described as Rd.

  Next, the reason why a detection value with a small variation due to the deflection of the optical sheet 106 can be obtained by using the optical sensor 113 provided at a position where Rd = 4.03 as the adjustment optical sensor will be described.

FIG. 6A is a schematic diagram illustrating an example of a positional relationship between the LED chip 112, the optical sensor 113, the LED substrate 110, and the optical sheet 106. The LED substrate 110 is disposed in parallel with the optical sheet 106. The LED chip 112 is disposed on the LED substrate 110 with the light emitting surface facing the optical sheet 106 side (the direction of the optical sheet side out of the directions perpendicular to the light source substrate). When the LED chip 112 is lit, the light 121 from the LED chip 112 spreads toward the optical sheet 106 side. Light emitted from a general LED has directivity having an intensity distribution that is substantially Lambertian distribution, and has the highest intensity in a direction perpendicular to the light emitting surface.
FIG. 7 is a graph showing an example of the relationship between the angle θ with respect to the direction perpendicular to the light emitting surface of the LED chip 112 and the intensity of the light emitted from the LED chip 112 (light emission intensity). FIG. 7 is an example when the light emission intensity distribution of the LED chip 112 is a Lambertian distribution. In FIG. 7, the y-axis indicates the emission intensity, and the x-axis indicates the angle θ. As shown in FIG. 7, the Lambertian distribution has a relationship of light emission intensity = cos θ, the light emission intensity is highest at an angle θ = 0 °, and the light emission intensity is zero at an angle θ = ± 90 °.
FIG. 6B is a graph showing an example of the luminance distribution on the back surface of the optical sheet 106 when only one LED chip 112 (only one light emitting unit) is turned on. In FIG. 6B, the y axis represents luminance, and the x axis represents the position on the optical sheet 106. Specifically, the x-axis indicates the distance from the position facing the LED chip 112. The luminance on the back surface of the optical sheet 106 is the light directly incident from the LED chip 112 (direct incident amount) and the light incident after repeated reflection between the optical sheet 106 and the LED substrate 110 (indirect incident amount). ) And the total. The luminance distribution on the back surface of the optical sheet 106 has a curve 150 in which the luminance becomes maximum when x = 0 (a position immediately above the LED chip 112) and decreases as the distance from the position where x = 0 is increased. A curve 150 is a luminance distribution when the optical sheet 106 is not bent.
Here, as shown in FIG. 6A, the optical sensor 113-1 is such that the detection surface of the optical sensor 113-1 faces the optical sheet 106 side (of the direction perpendicular to the light source substrate, the optical sheet side). −1 is arranged on the LED substrate 110. In that case, the optical sensor 113-1 detects the luminance corresponding to the luminance 151 at the position facing the optical sensor 113-1 in the luminance distribution of FIG. In order to optimize the S / N ratio in the detection value of the optical sensor, it is necessary to make the optical sensor as close to the LED chip 112 as possible and receive a larger amount of light. The design was made.

  FIG. 8 is a cross-sectional view showing an example of the deflection generated in the optical sheet 106. The peripheral portion of the optical sheet 106 is fixed by an optical sheet fixing member 157. However, due to factors such as thermal expansion, static electricity, aging, and gravity, the optical sheet 106 has a larger amount of deflection at the central portion and a smaller amount of deflection at the peripheral portion. In the deflection direction, a negative deflection 155 in which the entire optical sheet 106 approaches the LED substrate 110 and a positive deflection 156 in which the entire optical sheet 106 is separated from the LED substrate 110 are generated. In addition to these deflections, local deflections and swells may also occur, but in general, either the negative deflection 155 or the positive deflection 156 is dominant.

A dashed line 160 in FIG. 6A indicates the position of the optical sheet 106 bent in the minus direction. When the optical sheet 106 bends in the minus direction, the optical sheet 106 approaches the LED substrate 110 while maintaining a parallel relationship with the LED substrate 110. Originally, as shown in the cross-sectional view of FIG. 8, the amount of deflection increases toward the center of the optical sheet 106, but from a microscopic viewpoint limited to the periphery of the LED chip 112, the parallel relationship between the optical sheet 106 and the LED substrate 110 There is no problem even if it is assumed that
An alternate long and short dash line 161 in FIG. 6B indicates a luminance distribution on the back surface of the optical sheet 106 bent in the minus direction. In the curve 161, the brightness is higher near the position facing the LED chip 112 (near x = 0) than the curve 150, and the brightness is lower than the curve 150 at a position away from the position facing the LED chip 112. This is because when the optical sheet 106 approaches the LED chip 112, the spread of light from the LED chip 112 (spread of light until reaching the optical sheet 106) is suppressed. By suppressing the spread of the light from the LED chip 112, the light 121 is concentrated at a position facing the LED chip 112, and the light 121 is difficult to reach a position away from the position facing the LED chip 112.
When the optical sheet 106 is at the position of the alternate long and short dash line 160, the optical sensor 113-1 detects the luminance corresponding to the luminance 162 at the position facing the optical sensor 113-1 in the luminance distribution 161 of FIG. . The brightness 162 is higher than the brightness 151 when the optical sheet 106 is not bent at a position close to the LED chip 112 (near x = 0), and lower than the brightness 151 at a position far from the LED chip 112. That is, due to the change in the luminance distribution on the back surface of the optical sheet due to the deflection of the optical sheet, the amount of change in the detection value of the optical sensor due to the deflection of the optical sheet is Varies with distance. Originally, what should be detected by the optical sensor is a change in luminance due to temperature and aging deterioration. Thus, the change in luminance caused by the deflection of the optical sheet 106 becomes a detection error.

A broken line 170 in FIG. 6A indicates the position of the optical sheet 106 bent in the plus direction. When the optical sheet 106 bends in the plus direction, the optical sheet 106 is separated from the LED substrate 110 while maintaining a parallel relationship with the LED substrate 110.
A broken line 171 in FIG. 6B indicates a luminance distribution on the back surface of the optical sheet 106 bent in the plus direction. In the curve 171, the luminance is lower than the curve 150 near the position facing the LED 112 (near x = 0), and the luminance is higher than the curve 150 at a position away from the position facing the LED chip 112. This is because the light from the LED chip 112 is further spread when the optical sheet 106 is separated from the LED chip 112. As the spread of light from the LED chip 112 increases, the light 121 is less likely to concentrate at a position facing the LED chip 112, and the light 121 easily reaches a position away from the position facing the LED chip 112.
When the optical sheet 106 is at the position of the broken line 170, the optical sensor 113-1 detects the luminance corresponding to the luminance 172 at the position facing the optical sensor 113-1 in the luminance distribution 171 of FIG. 6B. The brightness 172 is lower than the brightness 151 when the optical sheet 106 is not bent at a position close to the LED chip 112 (near x = 0), and is higher than the brightness 151 at a position far from the LED chip 112. Similar to the case where the optical sheet 106 is bent in the minus direction, such a change in luminance becomes a detection error.

  From FIG. 6B, it can be seen that there is a position 180 where the curve 150, the curve 161, and the curve 171 coincide with each other (a position where the luminance change due to deflection becomes zero; a zero cross point of the curve). Therefore, in this embodiment, it is provided so as to face the vicinity of the position on the back surface of the optical sheet that becomes the zero cross point (the position on the back surface where the absolute value of the change in luminance due to the deflection of the optical sheet is a predetermined value or less). The optical sensor 113-2 is used as an adjustment optical sensor. In other words, the optical sensor 113-2 provided at a position where the absolute value of the change amount of the detection value due to the deflection of the optical sheet is equal to or less than a predetermined value is used as the adjustment optical sensor. Specifically, in this embodiment, for each light emitting unit, the absolute value of the change amount of the detected value due to the deflection of the optical sheet when only the light emitting unit among the plurality of optical sensors is turned on is less than or equal to a predetermined value. An optical sensor provided at a certain position is associated (FIG. 4). And when adjusting the light emission brightness | luminance of a light emission part, the optical sensor matched with the light emission part is used among several optical sensors. Thereby, the detection error of the optical sensor (the fluctuation of the detection value) due to the deflection of the optical sheet 106 can be reduced.

The installation position of the optical sensor 113 is not limited to the LED board 110. For example, the optical sensor 113 may be disposed in a hole provided in the LED substrate 110, or the optical sensor 113 may be disposed at a position away from the LED substrate 110.
In addition, DICOM part 14 is used as a display performance standard in a medical image display device that requires high accuracy. In DICOM part 14, the detection value of the photometer for calibrating the display luminance is required to be within 3% of the absolute luminance (Digital Imaging and Communications in Medicine (DICOM) Part 14: Grayscale Standard Display Display). reference). By using a photometer (that is, an optical sensor) that satisfies such accuracy, an error in display luminance can be suppressed to a level that cannot be discriminated by the user. Therefore, the adjustment optical sensor is opposed to a position on the back surface of the optical sheet in which the ratio of the luminance when the optical sheet is bent is 97% or more and 103% or less with respect to the luminance when the optical sheet is not bent. Is preferably provided. By using the adjustment optical sensor provided at such a position, it is possible to obtain a detection value with a smaller fluctuation due to the deflection of the optical sheet, and thus to adjust the light emission luminance of the light emitting unit with higher accuracy. .

Next, the relationship between the amount of change in luminance on the back surface of the optical sheet 106 and Rd (the ratio of the distance between the light emission center of the light emitting unit 111 and the optical sensor 113 to the diffusion distance 130) will be described.
FIG. 9 is an example when the light emission intensity distribution of the light emitting unit (LED chip) is substantially Lambertian distribution (when the light emission intensity follows cos θ). FIG. 9 shows an example where the LED pitch 131 and the diffusion distance 130 are the same. In FIG. 9, the x-axis indicates Rd, and the y-axis indicates the amount of change in luminance (luminance on the back surface of the optical sheet) due to deflection of the optical sheet. A curve 200 indicates the amount of change in luminance when the optical sheet 106 is bent in the negative direction. A curve 201 indicates the amount of change in luminance when the optical sheet 106 is bent in the plus direction.
From FIG. 9, it can be seen that the closer to the position facing the LED chip 112 (the position on the optical sheet facing the position of Rd = 0), the larger the amount of change in luminance due to the deflection of the optical sheet. It can also be seen that the position on the optical sheet facing the position where Rd is approximately 4 is the zero cross point, and that the amount of change in luminance increases when Rd is larger than this.
When the detection surface of the optical sensor 113 faces the optical sheet 106 side (the optical sheet side direction out of the directions perpendicular to the light source substrate), the y-axis indicates a detection error of the optical sensor 113.
Therefore, when the light emission intensity distribution is a substantially Lambertian distribution, the adjustment optical sensor used for adjusting the light emission luminance of the light emitting unit is the distance between the light emitting unit and the optical sheet from the light emission center of the light emitting unit. It is preferable to be provided at a position separated by a distance that is approximately four times the distance. Thereby, it is possible to obtain a detection value with less fluctuation due to the deflection of the optical sheet.
For the above reasons, in this embodiment, the distance between the light emitting unit 111 to be processed and the adjustment optical sensor is 4.03 times the diffusion distance 130. Thereby, it is possible to obtain a detection value with less fluctuation due to the deflection of the optical sheet.

  FIG. 10A is a graph showing an example of the relationship between the directivity of light from the light emitting unit (LED chip) and Rd indicating the position facing the zero cross point. In FIG. 10A, the x-axis indicates directivity, and the y-axis indicates Rd at a position facing the zero cross point. FIG. 10B is a graph showing an example of the relationship between the directivity of light from the light emitting unit (LED chip) and the light emission intensity distribution. The x-axis in FIG. 10B indicates the angle with respect to the direction on the optical sheet side in the direction perpendicular to the light source substrate, and the y-axis is a position separated by a predetermined distance in the direction on the optical sheet side in the direction perpendicular to the light source substrate. The emission luminance at is shown.

When the light emission intensity distribution of the light emitting portion is a Lambertian distribution (when the light emission intensity follows cos θ; the light emission intensity distribution is the curve 190 in FIG. 10B), Rd at a position facing the zero cross point is approximately 4. Become. On the other hand, when the directivity of light from the light emitting portion is high (for example, when the light emission intensity follows cos ³ θ; the light emission intensity distribution is the curve 191 in FIG. 10B), the position facing the zero cross point Rd is a value smaller than 4. This is because, as the directivity of light from the light emitting unit is higher, the spread of the luminance distribution on the back surface of the optical sheet is suppressed, and the zero cross point approaches the position facing the light emission center of the light emitting unit. Further, when the directivity of light from the light emitting portion is weak (for example, when the light emission intensity follows cos ^1/3 θ; the light emission intensity distribution is the curve 192 in FIG. 10B), the position facing the zero cross point Rd at 4 is a value greater than 4. The directivity can be controlled by using a lens or a reflector that changes the directivity or diffusibility of light.

  Therefore, when the light source substrate includes a plurality of light emitting units that emit light having different directivities, it is preferable that the distance between the light emitting unit 111 to be processed and the adjustment optical sensor is not uniform. Specifically, the distance between the light emission center of the light emitting unit that emits light with high directivity and the optical sensor used for adjusting the light emission luminance of the light emitting unit is that of the light emitting unit that emits light with low directivity. It is preferable that the distance is shorter than the distance between the light emission center and the optical sensor used when adjusting the light emission luminance of the light emitting portion.

FIG. 11 is a correspondence table in the case where the light source substrate has a plurality of light emitting units that emit light having different directivities (the processing order of the plurality of light emitting units 111 and the correspondence relationship between the light emitting units 111 and the adjustment light sensors). It is a figure which shows an example of a correspondence table | surface. In the example of FIG. 4, the light sensor 113 provided at a position where Rd = 4.03 is used as the adjustment light sensor when adjusting the light emission luminance for all the light emitting units 111. In the example of FIG. 11, for the light emitting unit 111 arranged at the edge of the light source substrate, the optical sensor 113 provided at a position where Rd = 4.72 or 5.02 is used as the adjustment optical sensor. Specifically, the light emitting units 111 (1, 1, 1) to 111 (1, 1, 5), 111 (1, 2, 1) to 111 (1, 2, 4), 111 (1, 2, 8) ), 111 (2, 1, 1), 111 (2, 1, 5) to 111 (2, 1, 8), 111 (2, 2, 4) to 111 (2, 2, 8) in total When adjusting the light emission luminance of each of the light emitting units 111, the optical sensor 113 provided at a position where Rd = 4.72 or 5.02 is used as an adjustment optical sensor.

This is because the light 121 from the LED chip 112 is reflected by the side wall surface of the backlight device, so that the directivity of light from the light emitting unit is reduced. Specifically, the closer to the edge of the light source substrate, the lower the directivity of light from the light emitting part. FIG. 12A is a graph showing an example of the directivity of light from the LED chip 112. A curve 190 shows a Lambertian distribution. The intensity distribution of light from the light emitting portion arranged at the edge of the light source substrate is a curve 193 having a lower directivity than the curve 190 (Lambert distribution).
Therefore, in the example of FIG. 11, the distance between the light emission center of the light emitting unit close to the edge of the light source substrate and the adjustment optical sensor corresponding to the light emitting unit is light emission of the light emitting unit far from the edge of the light source substrate. The light emitting unit and the adjustment optical sensor are associated with each other so as to be longer than the distance between the center and the adjustment optical sensor corresponding to the light emission unit.
In this way, by using the optical sensor 113 having a large Rd when adjusting the light emission luminance of the light emitting unit 111 that emits light with low directivity, the detection error of the optical sensor 113 due to the deflection of the optical sheet 106 can be further reduced.

FIG. 12B is a schematic diagram illustrating a positional relationship between the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 2, 2) (adjustment optical sensor). In the present embodiment, when adjusting the light emission luminance of the light emitting unit 111 (1, 1, 1), detection is performed by the deflection of the optical sheet 106 instead of the optical sensor 113 closest to the light emitting unit 111 (1, 1, 1). The optical sensor 113 (1, 2, 2) at a position where the error is reduced is used. Since the vertical distance 230 is 0.5 times the LED pitch 131 and the horizontal distance 231 is 5 times the LED pitch 131, the light emitting unit 111 (
It can be seen that the distance between the light emission center of (1, 1, 1) and the optical sensor 113 (1, 2, 2) is 5.02 times the LED pitch 131. In the present embodiment, since the LED pitch 131 and the diffusion distance 130 are equivalent, the distance between the light emission center of the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 2, 2) is It can also be seen that it is 5.02 times the diffusion distance 130.
FIG. 12C is a schematic diagram showing a positional relationship between the light emitting unit 111 (1, 1, 4) and the optical sensor 113 (2, 2, 4) (adjustment optical sensor). In the present embodiment, when adjusting the light emission luminance of the light emitting unit 111 (1, 1, 4), detection is performed by the deflection of the optical sheet 106 instead of the optical sensor 113 closest to the light emitting unit 111 (1, 1, 4). The optical sensor 113 (2, 2, 4) at a position where the error is reduced is used. Since the vertical distance 240 is 2.5 times the LED pitch 131 and the horizontal distance 241 is four times the LED pitch 131, the light emission center and light of the light emitting unit 111 (1, 1, 4) are calculated from the three square theorem. It can be seen that the distance to the sensor 113 (2, 2, 4) is 4.72 times the LED pitch 131. In this embodiment, since the LED pitch 131 and the diffusion distance 130 are equal, the distance between the light emission center of the light emitting unit 111 (1, 1, 4) and the optical sensor 113 (2, 2, 4) is It can also be seen that it is 4.72 times the diffusion distance 130.

As described above, according to the present embodiment, a detection value with small fluctuation due to the deflection of the optical sheet can be obtained as the detection value of the reflected light from the optical sheet. Can be adjusted.
In this embodiment, an example in which the light source substrate has a plurality of light emitting units has been described, but the light source substrate may have one light emitting unit. In that case, it is only necessary to provide one optical sensor used when adjusting the light emission luminance of the one light emitting unit. And the said optical sensor should just be provided so that the absolute value of the variation | change_quantity of the brightness | luminance by the bending of an optical sheet may oppose the position on the back surface of the optical sheet which is below a predetermined value. For example, as shown in FIGS. 13A to 13C, the light source substrate may have one light emitting unit. When the light emission intensity distribution of the light emitting part is substantially Lambertian distribution, the optical sensor may be provided at a position separated from the light emission center of the light emitting part by a distance approximately four times the diffusion distance. In FIG. 13A, the optical sensor is provided at the edge of the light emitting portion. In FIG. 13B, the optical sensor is provided outside the light emitting portion. In FIG. 13C, the optical sensor is provided inside the light emitting portion.
In the present embodiment, an example in which the detection surface of the optical sensor 113 faces the optical sheet 106 side (the direction on the optical sheet side out of the directions perpendicular to the light source substrate) has been described, but the present invention is not limited to this. . If the detection surface of the optical sensor 113 is directed to a zero cross point on the optical sheet (a position where the change in luminance due to deflection is a predetermined value or less), the detection surface is directed in a direction inclined with respect to a direction perpendicular to the light source substrate. Also good.
In this embodiment, when detecting light from the light emitting unit (specifically, reflected light), only the light emitting unit is turned on. However, the light emission has little influence on the light from the light emitting unit. The part may be lit.

<Example 2>
Hereinafter, a light source device according to a second embodiment of the invention will be described. In the first embodiment, an example in which one light source (LED chip 112) is provided in one light emitting unit 111 and the LED pitch 131 and the diffusion distance 130 are equal to each other has been described. In the present embodiment, an example in which a plurality of light sources (a plurality of LED chips 112) are provided in one light emitting unit 111 and the LED pitch 131 and the diffusion distance 130 are not equivalent will be described. In addition, the same code | symbol is attached | subjected to the same member as Example 1, and the description is omitted.

In the first embodiment, one LED chip 112 is provided in one light emitting unit 111, but a total of four LED chips 112, for example, 2 rows × 2 columns, 3 rows × 3 columns, are provided in one light emitting unit 111. It is conceivable to provide a total of nine LED chips 112.
FIG. 14A is a schematic diagram showing an example in which a total of four LED chips 112 of 2 rows × 2 columns are arranged in one light emitting unit 111. The four LED chips 112 are arranged at equal intervals. The point 301 is the center point of the light emitting unit 111, and the center point of the four LED chips 112 and the center point 301 coincide. Therefore, the light emission center of the light emitting unit 111 is a point 301.
FIG. 14B is a schematic diagram illustrating an example in which a total of four LED chips 300 of 2 rows × 2 columns are arranged in one light emitting unit 111. In FIG. 14A, one white LED is used as one LED chip 112, but in FIG. 14B, one LED chip 300 is formed using a plurality of LEDs having different colors of emitted light. It is configured. Specifically, one LED chip 300 includes four LEDs, one red LED that emits red light, two green LEDs that emit green light, and one blue LED that emits blue light. ing. One LED chip 300 may be considered to correspond to one LED chip 112 in FIG. Therefore, FIG. 14A and FIG. 14B may be considered equivalent. The point 302 is the center point of the light emitting unit 111, and the center point of the four LED chips 300 and the center point 302 coincide. Therefore, the light emission center of the light emitting unit 111 is a point 302.
FIG. 14C is a schematic diagram illustrating an example in which a total of nine LED chips 112 of 3 rows × 3 columns are arranged in one light emitting unit 111. Nine LED chips 112 are arranged at equal intervals. The point 303 is the center point of the light emitting unit 111, and the center points of the nine LED chips 112 coincide with the center point 303. Therefore, the light emission center of the light emitting unit 111 is a point 303.

  The graph of FIG. 9 of Example 1 shows that the detection error of the optical sensor 113 is the smallest when Rd is around 4 when a general LED chip whose emission intensity distribution is Lambertian distribution (cos θ) is used. . That is, the graph of FIG. 9 shows that the position on the optical sheet facing Rd near 4 is the zero cross point. Even when a plurality of LED chips 112 are arranged in one light emitting unit 111, it may be considered in the same manner as a case where one LED chip 112 is arranged in one light emitting unit 111. This will be described below.

FIG. 15 shows an example of the relationship between the amount of change in luminance on the back surface of the optical sheet 106 and Rd. The x axis in FIG. 15 represents Rd. The y-axis in FIG. 15 indicates the amount of change in luminance (luminance on the back surface of the optical sheet) due to deflection of the optical sheet, that is, the detection error of the optical sensor.
Curves 200 and 201 indicate detection errors when one LED chip is arranged in one light emitting unit 111. A curve 200 indicates a detection error when the optical sheet 106 is bent in the minus direction. A curve 201 indicates a detection error when the optical sheet 106 is bent in the plus direction.
Curves 310 and 311 indicate detection errors when a total of four LED chips of 2 rows × 2 columns are arranged in one light emitting unit 111. A curve 310 indicates a detection error when the optical sheet 106 is bent in the minus direction. A curve 311 indicates a detection error when the optical sheet 106 is bent in the plus direction.
Curves 320 and 321 indicate detection errors when a total of nine LED chips of 3 rows × 3 columns are arranged in one light emitting unit 111. A curve 320 indicates a detection error when the optical sheet 106 is bent in the minus direction. A curve 321 indicates a detection error when the optical sheet 106 is bent in the plus direction.
From FIG. 15, it can be seen that the zero cross point does not depend on the number of LED chips 112 arranged in one light emitting unit 111. Specifically, when the light emission intensity distribution of the light emitting unit 111 (light emission intensity distribution of each LED chip 112) is substantially Lambertian distribution, the position on the optical sheet facing the position where Rd is substantially 4 is the zero cross point. It turns out that it becomes. That is, when the light emission intensity distribution is substantially Lambertian distribution, the detection error of the optical sensor 113 is at a position away from the light emission center of the light emitting unit by a distance that is approximately four times the distance between the light emitting unit and the optical sheet. You can see that it is the smallest.

FIG. 16A shows an example of the positional relationship between the light emitting unit and the adjustment optical sensor corresponding to the light emitting unit when a total of four LED chips of 2 rows × 2 columns are arranged in one light emitting unit. It is a schematic diagram shown.
In the example of FIG. 16A, when adjusting the light emission luminance of the light emitting unit 330, the third closest optical sensor 332 to the light emitting unit 330 is used instead of the optical sensor closest to the light emitting unit 330. It can be seen that the distance 334 between the light emission center of the light emitting unit 330 and the optical sensor 332 is 4.00 times the LED pitch 333. If the LED pitch 333 and the diffusion distance 130 are equal, the distance between the light emission center of the light emitting unit 330 and the optical sensor 332 is 4.00 times the diffusion distance 130 (that is, Rd = 4.00). I understand that. As a result, the detection error due to the deflection of the optical sheet 106 can be sufficiently reduced.
FIG. 16B shows an example of the positional relationship between the light emitting unit and the adjustment optical sensor corresponding to the light emitting unit when a total of nine LED chips of 3 rows × 3 columns are arranged in one light emitting unit. It is a schematic diagram shown.
In the example of FIG. 16B, when adjusting the light emission luminance of the light emitting unit 340, the second closest optical sensor 342 to the light emitting unit 340 is used instead of the optical sensor closest to the light emitting unit 340. Since the vertical distance 345 is 0.5 times the LED pitch 343 and the horizontal distance 344 is 3.5 times the LED pitch 343, from the three square theorem, the distance between the light emission center of the light emitting unit 340 and the optical sensor 342 is determined. This distance is 3.54 times the LED pitch 343. If the LED pitch 343 and the diffusion distance 130 are equal, the distance between the light emission center of the light emitting unit 340 and the optical sensor 342 is 3.54 times the diffusion distance 130 (that is, Rd = 3.54). I understand that. As a result, the detection error due to the deflection of the optical sheet 106 can be sufficiently reduced.

  In the examples of FIGS. 16A and 16B, an example in which the optical sensor closest to the light emitting unit is not used is shown. However, even if the optical sensor closest to the light emitting unit is used, the optical sheet 106 is bent. The detection error due to can be reduced. FIG. 17 shows an example of a configuration that can reduce the detection error due to the deflection of the optical sheet 106 even when the optical sensor closest to the light emitting unit is used.

FIG. 17 is a schematic diagram illustrating an example of a positional relationship between a light emitting unit and an adjustment optical sensor corresponding to the light emitting unit when a total of 18 LED chips of 6 rows × 6 columns are arranged in one light emitting unit. It is.
In the example of FIG. 17, the optical sensor 352 closest to the light emitting unit 350 is used when adjusting the light emission luminance of the light emitting unit 350. Since the vertical distance 355 is three times the LED pitch 353 and the horizontal distance 354 is three times the LED pitch 353, the distance between the light emission center of the light emitting unit 350 and the optical sensor 352 is calculated from the three-square theorem. It can be seen that the pitch is 4.24 times the pitch 353. Assuming that the LED pitch 353 and the diffusion distance 130 are equal, the distance between the light emission center of the light emitting unit 350 and the optical sensor 352 is 4.24 times the diffusion distance 130 (that is, Rd = 4.24). I understand that. As described above, when the size of one light emitting unit is large, the detection error due to the deflection of the optical sheet 106 can be sufficiently reduced even when the optical sensor closest to the light emitting unit is used.

  FIG. 18A is a cross-sectional view showing an example of the arrangement relationship between the LED substrate 110 and the optical sheet 106 when the diffusion distance is twice the LED pitch. On the LED substrate 110, LED chips 112 are arranged at equal intervals. An interval between the LED chips 112 is an LED pitch 361. The optical sheet 106 is arranged in parallel with the LED substrate 110. A distance between the optical sheet 106 and the LED substrate 110 is a diffusion distance 360. In the backlight device using the LED chip 112 having general directivity, the brightness of light after passing through the optical sheet 106 is arranged by arranging each member so that the diffusion distance 360 is sufficiently longer than the LED pitch 361. Unevenness can be sufficiently reduced.

FIG. 18B shows an example of the positional relationship between the light emitting unit and the adjustment optical sensor corresponding to the light emitting unit when a total of four LED chips of 2 rows × 2 columns are arranged in one light emitting unit. It is a schematic diagram shown. FIG. 18B shows an example in which the diffusion distance is twice the LED pitch.
In the example of FIG. 18B, when adjusting the light emission luminance of the light emitting unit 370, the second closest optical sensor 372 to the light emitting unit 370 is used instead of the optical sensor closest to the light emitting unit 370. Light emitting part 3
It can be seen that the distance between the light emission center 70 and the optical sensor 372 is 2.00 times the LED pitch 361. Here, since the diffusion distance 130 is twice the LED pitch 361, the distance between the light emission center of the light emitting unit 370 and the optical sensor 372 is 4.00 times the diffusion distance 130 (that is, Rd = 4.00). It is also understood. As a result, the detection error due to the deflection of the optical sheet 106 can be sufficiently reduced.

As described above, according to the present embodiment, even when a plurality of light sources are provided on the light source substrate or when the LED pitch and the diffusion distance are not equal, the optical sheet is the same as in the first embodiment. A detection value with a small fluctuation due to the deflection can be obtained.

<Example 3>
Hereinafter, a light source device according to Example 3 of the invention will be described. In the first and second embodiments, the configuration using the optical sensor provided so as to face the position on the back surface of the optical sheet 106 in which the variation in luminance due to the deflection of the optical sheet 106 is sufficiently small has been described. However, if such optical sensors can be used for all the light emitting units 111, the number of optical sensors 113 increases, and the manufacturing cost increases. In this embodiment, a configuration that can reduce luminance unevenness of a light source device using a small number of optical sensors 113 will be described. In addition, the same code | symbol is attached | subjected to the same member as Example 1 and Example 2, and the description is omitted.

  FIG. 19A is a schematic diagram illustrating an example of the configuration of the LED substrate 110 according to the present embodiment. In FIG. 19A, the LED substrate 110 has a total of four light emitting portions 111 of 2 rows × 2 columns. In each light emitting unit 111, four LED chips 112 are arranged at equal intervals. The backlight device (light source device) according to the present embodiment can adjust the light emission luminance for each light emitting unit 111. Each LED substrate 110 is provided with one optical sensor 113. The optical sensor 113 is disposed at the center of the four light emitting units 111 (that is, the center of the LED substrate 110). For this reason, in this embodiment, the number of optical sensors is smaller than in the case where optical sensors are arranged as shown in FIGS.

FIG. 19B is a schematic diagram illustrating an example of the arrangement of the LED substrate 110, the light emitting unit 111, and the optical sensor 113 when viewed from the front direction (color liquid crystal panel 105 side). On the right side of the LED board 110 (1, 1) arranged at the upper left end, the LED board 110 (1, 2), the LED board 110 (1, 3), and the LED board 110 (1, 4) are arranged in that order. Has been. Below the LED board 110 (1, 1) arranged at the upper left end, the LED board 110 (2, 1) and the LED board 110 (3, 1) are arranged in that order. On the right side of the LED board 110 (2, 1), the LED board 110 (2, 2), the LED board 110 (2, 3), and the LED board 110 (2, 4) are arranged in that order. On the right side of the LED board 110 (3, 1), the LED board 110 (3, 2), the LED board 110 (3, 3), and the LED board 110 (3, 4) are arranged in this order. As described above, the light source substrate 101 has a total of 12 LED substrates 110 (48 rows of light emitting units 111 of 6 rows × 8 columns) of 3 rows × 4 columns.
The LED substrate 110 (1, 1) includes a light emitting unit 111 (1, 1, 1), a light emitting unit 111 (1, 1, 2), a light emitting unit 111 (1, 1, 3), and a light emitting unit 111 (1, 1). , 4). The LED substrate 110 (1, 1) is provided with an optical sensor 113 (1, 1). The same applies to other LED substrates.

  FIG. 19C is a cross-sectional view illustrating an example of an arrangement relationship between the LED substrate 110 and the optical sheet 106. Each LED chip 112 is arranged at equal intervals. The interval between the LED chips 112 is defined as an LED pitch 401. The optical sheet 106 is arranged in parallel with the LED substrate 110. A distance between the optical sheet 106 and the LED substrate 110 is a diffusion distance 400. Here, it is assumed that the LED pitch 401 and the diffusion distance 400 are equal.

FIG. 20 is a correspondence table showing an example of processing order of the plurality of light emitting units 111 and a correspondence relationship between the light emitting units 111 and the adjustment optical sensors. The process described in the first embodiment (the process of acquiring the detection value and outputting it to the microcomputer 125) is performed 48 times, the same as the number of the light emitting units 111. In FIG. 20, only four LED substrates 110 (1, 1) to 110 (1, 4) are shown for simplicity. The correspondence relationship between the light emitting unit 111 and the adjustment optical sensor in the other LED substrates is the same as that of the LED substrates 110 (1, 1) to 110 (1, 4).
In the first process, the light emitting unit 111 (1, 1, 1) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (1, 2) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (1, 2) is output to the microcomputer 125.
FIG. 21A is a schematic diagram showing a positional relationship between the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 2) when viewed from the front direction (color liquid crystal panel 105 side). . Instead of the optical sensor 113 closest to the light emitting unit 111 (1, 1, 1), the optical sensor 113 (1, 2) located relatively far from the light emitting unit 111 (1, 1, 1) is used. Since the vertical distance 410 is 1 times the LED pitch 401 and the horizontal distance 411 is 5 times the LED pitch 401, the light emission center of the light emitting unit 111 (1, 1, 1) and the optical sensor 113 are calculated from the three square theorem. It can be seen that the distance between (1, 2) is 5.10 times the LED pitch 401. In this embodiment, since the LED pitch 401 and the diffusion distance 400 are equivalent, the distance between the light emission center of the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 2) is the diffusion distance. It can also be seen that it is 5.10 times 400 (Rd = 5.10).

As shown in FIG. 20, in the second process, the light emitting units 111 (1, 1, 2) are turned on, and the other light emitting units 111 are turned off. Then, the optical sensor 113 (1, 2) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (1, 2) is output to the microcomputer 125.
FIG. 21B is a schematic diagram showing a positional relationship between the light emitting units 111 (1, 1, 2) and the optical sensors 113 (1, 2) when viewed from the front direction (color liquid crystal panel 105 side). . By a calculation method similar to the calculation method described in the description of the first process, the distance between the light emission center of the light emitting unit 111 (1, 1, 2) and the optical sensor 113 (1, 2) is the diffusion distance 400. It turns out that it is 3.16 times (Rd = 3.16).

  The third and subsequent processes are similarly performed in the order shown in the correspondence table of FIG. At this time, the distance between the light emission center of the light emitting unit 111 to be processed and the adjustment optical sensor is 5.10 times or 3.16 times the diffusion distance 400.

As described above, at a position on the back surface of the optical sheet facing the position where Rd is approximately 4, the change in luminance due to the deflection of the optical sheet is substantially zero.
In the present embodiment, the plurality of light emitting units include a second light emitting unit and a third light emitting unit. The optical sensor used when adjusting the light emission luminance of the second light emitting unit is on the back surface of the optical sheet in which the amount of change in luminance due to the deflection of the optical sheet when only the second light emitting unit is turned on is substantially zero. It is provided at a position farther from the second light emitting unit than a position facing the position. The optical sensor used for adjusting the light emission luminance of the third light emitting unit is a position on the back surface of the optical sheet where the amount of change in luminance due to the deflection of the optical sheet when only the third light emitting unit is turned on is substantially zero. It is provided at a position closer to the third light emitting unit than a position facing the.

FIG. 22 is a schematic diagram illustrating an example of the positional relationship between the light emitting unit 111 and the adjustment optical sensor. In FIG. 22, the light emitting unit 111 (second light emitting unit) where the position of the adjustment optical sensor is Rd = 5.10 is filled with a hatched pattern. For example, the light emitting unit 111 (1, 1, 1) and the light emitting unit 111 (1, 2, 2) are the second light emitting units. In FIG. 22, the light emitting unit 111 (third light emitting unit) where the position of the adjustment optical sensor is Rd = 3.16 is filled with a dot pattern. For example, the light emitting unit 111 (1, 1, 2) or the light emitting unit 111 (1, 2, 1) is the third light emitting unit. In FIG. 22, the numbers of the second light emitting units and the third light emitting units are equal to each other. In the present embodiment, the second light emitting unit and the third light emitting unit are arranged in a distributed manner so that an error in light emission luminance after adjustment due to a change in luminance distribution on the back surface of the optical sheet is offset. Specifically, the second light emitting unit and the third light emitting unit are adjacent to each other.

FIG. 23 shows an example of the relationship between the amount of change in luminance on the back surface of the optical sheet 106 and Rd. The x axis in FIG. 23 represents Rd. The y axis in FIG. 23 indicates the amount of change in luminance (luminance on the back surface of the optical sheet) due to deflection of the optical sheet, that is, the detection error of the optical sensor. A curve 200 indicates a detection error when the optical sheet 106 is bent in the minus direction. A curve 201 indicates a detection error when the optical sheet 106 is bent in the plus direction. The position opposite to the position where Rd is approximately 4 is the zero cross point.
When the optical sheet 106 bends in the minus direction, a positive error occurs at a position facing the position of Rd = 3.16, as indicated by a point 430 (a larger detection value is obtained than when the optical sheet is not bent). . Further, at a position opposite to the position of Rd = 5.10, a negative error occurs as indicated by a point 431.

FIG. 24A is a graph showing an example of the distribution of detection errors of the adjustment optical sensor when the optical sheet 106 is bent in the minus direction. In FIG. 24A, the x-axis represents eight light emitting portions 111 (2,1,1), 111 (2,1,2), 111 (2,2,1), 111 (2, 2, 2), 111 (2, 3, 1), 111 (2, 3, 2), 111 (2, 4, 1), 111 (2, 4, 2). The y-axis in FIG. 24A indicates the detection error of the adjustment optical sensor when the optical sheet 106 is bent by a certain amount in the minus direction.
Although the absolute value is not large, a negative error occurs in the detection value of the adjustment optical sensor corresponding to the light emitting unit 111 (2, 1, 1), and the adjustment value corresponding to the light emitting unit 111 (2, 1, 2) is generated. Although the absolute value is not large, a positive error occurs in the detection value of the optical sensor. Similarly, the detection value of the adjustment optical sensor corresponding to the light emitting unit 111 (2, 2, 1) has a positive error although the absolute value is not large, and corresponds to the light emitting unit 111 (2, 2, 2). Although the absolute value is not large, a negative error occurs in the detection value of the adjusting optical sensor. Note that the absolute value of the detection error is larger in the light emitting unit 111 located near the center than in the light emitting unit 111 located near the end of the backlight device. This is because the amount of deflection of the optical sheet 106 is greater near the center than near the edges. In any case, the detection error is not large.
From FIG. 24A, it can be seen that the light emitting unit 111 in which a minus detection error occurs and the light emitting unit 111 in which a plus detection error occurs are adjacent to each other.

FIG. 24C is a graph showing the luminance distribution of the backlight device after the light emission luminance adjustment when the optical sheet 106 is bent in the negative direction. FIG. 24C shows a luminance distribution (luminance distribution on the front surface of the optical sheet (on the surface opposite to the back surface)) when all the light emitting units are turned on. The x-axis in FIG. 24C is the same as the x-axis in FIG. The y-axis in FIG. 24C indicates a luminance error when all the light emitting units are turned on with the adjusted light emission luminance. As described above, an error occurs in the detection value of the optical sensor 113 due to the deflection of the optical sheet 106. If the emission luminance is adjusted based on the detected value having such an error, an error (deviation from the target value) occurs in the adjusted emission luminance. As a result, an error also occurs in the luminance when all the light emitting units are turned on with the adjusted emission luminance. A curve 440 shows the result when the light emission luminance is adjusted according to the correspondence table of FIG.
As shown in FIG. 24A, a negative error occurs in the detected value in the light emitting unit 111 (2, 1, 1). Therefore, a positive error occurs in the light emission luminance after adjustment. On the other hand, a positive error occurs in the detected value in the light emitting unit 111 (2, 1, 2). Therefore, a negative error occurs in the light emission luminance after adjustment. However, since the light from the light emitting part is sufficiently diffused in the backlight device, an error in the light emission luminance between the light emitting parts 111 (2, 1, 1) and the light emitting parts 111 (2, 1, 2) adjacent to each other is offset. Is done. As a result, as shown by a curve 440 in FIG. 24C, the error in luminance (luminance on the front surface of the optical sheet) when all the light emitting units are turned on with the adjusted emission luminance becomes a small value. The light emission luminance error is canceled between the other light emitting units 111 such as the light emitting unit 111 (2, 2, 1) and the light emitting unit 111 (2, 2, 2). The luminance error is a small value.

Here, as a comparison, in the light source substrate 101 of FIG. 19B, an example in the case where the light emission luminance of the light emitting unit 111 is adjusted using the detection value of the optical sensor 113 closest to the light emitting unit 111 as in the past is shown. .
FIG. 25 is an example of a correspondence table when the light emission luminance is adjusted by a conventional method.
In the first process, the light emitting unit 111 (1, 1, 1) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (1, 1) closest to the light emitting unit 111 (1, 1, 1) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (1, 1) is output to the microcomputer 125. The
FIG. 21C is a schematic diagram illustrating a positional relationship between the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 1) when viewed from the front direction (color liquid crystal panel 105 side). . The optical sensor 113 (1, 1) closest to the light emitting unit 111 (1, 1, 1) is used. Since the vertical distance 450 is one time the LED pitch 401 and the horizontal distance 451 is one time the LED pitch 401, the light emission center of the light emitting unit 111 (1, 1, 1) and the optical sensor 113 are calculated from the three-square theorem. It can be seen that the distance between (1, 1) is 1.41 times the LED pitch 401. In this embodiment, since the LED pitch 401 and the diffusion distance 400 are equal, the distance between the light emission center of the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 1) is the diffusion distance. It can also be seen that it is 1.41 times 400 (Rd = 1.41).
The third and subsequent processes are similarly performed in the order shown in FIG. At that time, the distance between the light emission center of the light emitting unit 111 and the adjustment optical sensor is all 1.41 times the diffusion distance 400 (Rd = 1.41).

When the optical sheet 106 bends in the minus direction, a positive error having a large absolute value is generated in the detection value of the photosensor at the position of Rd = 1.41, as indicated by a point 432 in FIG.
FIG. 24B is a graph showing an example of the distribution of detection errors of the adjustment optical sensor when the optical sheet 106 is bent in the minus direction. The x-axis and y-axis in FIG. 24B are the same as the x-axis and y-axis in FIG. However, FIG. 24B shows a detection error when the adjustment optical sensor is selected according to the correspondence table of FIG.
In the example of FIG. 24B, a positive detection error with a large absolute value occurs in all the light emitting units 111. Further, the absolute value of the detection error is larger in the light emitting unit 111 located near the center than in the light emitting unit 111 located near the end of the backlight device. This is because the amount of deflection of the optical sheet 106 is greater near the center than near the edges.

A curve 460 in FIG. 24C shows a result when the light emission luminance is adjusted according to the correspondence table in FIG.
As shown in FIG. 24B, a positive error occurs in the detected value in the light emitting unit 111 (2, 1, 1). Therefore, a negative error occurs in the light emission luminance after adjustment. Similarly, in all other light emitting units 111 such as the light emitting unit 111 (2, 1, 2), a positive error occurs in the detection value, and thus a negative error occurs in the adjusted light emission luminance.
When the correspondence table of FIG. 20 is followed, the error in the light emission luminance is canceled out, so that the error can be reduced as shown by the curve 440. On the other hand, when the optical sensor closest to the light emitting unit is used according to the correspondence table of FIG. 25, not only the absolute value of the detection error is large, but also the error of the light emission luminance is not canceled out. A large negative error in absolute value occurs in the brightness on the front surface of the sheet.

Next, the case where the optical sheet 106 is bent in the plus direction will be described. In the present embodiment, by following the correspondence table of FIG. 20, even when the optical sheet 106 is bent in the plus direction, an error in luminance on the front surface of the optical sheet can be reduced.
When the optical sheet 106 bends in the plus direction, a negative error occurs as shown by a point 470 in FIG. 23 at a position facing the position of Rd = 3.16. Further, at a position opposite to the position of Rd = 5.10, a positive error occurs as indicated by a point 471 in FIG.
FIG. 26A is a graph illustrating an example of a distribution of detection errors of the adjustment optical sensor when the optical sheet 106 is bent in the plus direction. The x-axis and y-axis in FIG. 26A are the same as the x-axis and y-axis in FIG. From FIG. 26A, as in the case where the optical sheet 106 bends in the minus direction (FIG. 24A), the light emitting unit 111 in which a negative detection error occurs and the light emitting unit 111 in which a positive detection error occurs. It can be seen that they are adjacent to each other.
FIG. 26B is a graph showing the luminance distribution of the backlight device after the light emission luminance adjustment when the optical sheet 106 is bent in the plus direction. The x-axis and y-axis in FIG. 26B are the same as the x-axis and y-axis in FIG. From FIG. 26B, as in the case where the optical sheet 106 bends in the minus direction (FIG. 24C), the error in the light emission luminance is canceled between the light emitting portions 111, so that It can be seen that the luminance error is a small value.

  As described above, in this embodiment, the second light emitting unit (the light emitting unit in which the adjustment light sensor is disposed at the position of Rd = 5.10) and the third light emitting unit (the position of Rd = 3.16 are used for adjustment). And the light emitting units where the optical sensors are arranged). Thereby, the number of optical sensors can be reduced, and an error in luminance on the front surface of the optical sheet when all the light emitting units are turned on with the adjusted emission luminance can be reduced.

In the example of FIG. 19B, the number of LED substrates 110 and the number of optical sensors 113 are the same (12). Next, a configuration that can reduce the luminance error on the front surface of the optical sheet even when the number of the optical sensors 113 is further reduced will be described.
FIG. 27 is a schematic diagram illustrating an example when the number of optical sensors 113 is further reduced from FIG. Specifically, in FIG. 27, the optical sensors 113 (1, 1), 113 (1, 2), 113 (1, 3), 113 (1, 4), 113 (3, 1) of FIG. ), 113 (3, 2), 113 (3, 3), 113 (3, 4) are excluded, and the number of optical sensors 113 is four.

FIG. 28 is a correspondence table when the number of optical sensors 113 is further reduced from the case of FIG. The process described in the first embodiment (the process of acquiring the detection value and outputting it to the microcomputer 125) is performed 48 times, the same as the number of the light emitting units 111. FIG. 28 illustrates processing (first to sixteenth processing) for four LED substrates 110 (1, 1) to 110 (1, 4).
In the first process, the light emitting unit 111 (1, 1, 1) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (2, 1) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (2, 1) is output to the microcomputer 125. Here, Rd = 5.10 at the position of the optical sensor 113 (2, 1).
In the second process, the light emitting units 111 (1, 1, 2) are turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (2, 1) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (2, 1) is output to the microcomputer 125. Again, Rd = 5.10 at the position of the optical sensor 113 (2, 1).
In the third process, the light emitting unit 111 (1, 1, 3) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (2, 1) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (2, 1) is output to the microcomputer 125. Here, Rd = 3.16 at the position of the optical sensor 113 (2, 1).
Similarly, in the fourth process, Rd = 3.16 at the position of the adjustment optical sensor. Thereafter, the processes up to the 16th are similarly performed. At that time, Rd is either 5.10 or 3.16 at the position of the adjustment optical sensor.

  The 17th to 32nd processes are performed in the same manner as the process according to the correspondence table shown in FIG. For example, in the process for the 17th light emitting unit 111 (2, 1, 1), the optical sensor 113 (2, 2) is selected as the adjustment optical sensor, and Rd = 5.10 at the position of the adjustment optical sensor. . In the process for the 18th light emitting unit 111 (2, 1, 2), the optical sensor 113 (2, 2) is selected as the adjustment optical sensor, and Rd = 3.16 at the position of the adjustment optical sensor. In the process for the 21st light emitting unit 111 (2, 2, 1), the optical sensor 113 (2, 1) is selected as the adjustment optical sensor, and Rd = 3.16 at the position of the adjustment optical sensor. . In the process for the 22nd light emitting unit 111 (2, 2, 2), the optical sensor 113 (2, 1) is selected as the adjustment optical sensor, and Rd = 5.10 is set at the position of the adjustment optical sensor.

FIG. 29 is a correspondence table when the number of photosensors 113 is further reduced from the case of FIG. 19B (in the case of the configuration of FIG. 27). FIG. 29 illustrates a process (from the 33rd to the 48th process) for four LED boards 110 (3, 1) to 110 (3, 4).
In the 33rd process, the light emitting unit 111 (3, 1, 1) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (2, 1) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (2, 1) is output to the microcomputer 125. Here, Rd = 3.16 at the position of the optical sensor 113 (2, 1).
In the 34th process, the light emitting units 111 (3, 1, 2) are turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (2, 1) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (2, 1) is output to the microcomputer 125. Again, Rd = 3.16 at the position of the photosensor 113 (2,1).
In the 35th process, the light emitting unit 111 (3, 1, 3) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (2, 1) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (2, 1) is output to the microcomputer 125. Here, Rd = 5.10 at the position of the optical sensor 113 (2, 1).
Similarly, in the 36th process, Rd = 5.10 at the position of the adjustment optical sensor. Thereafter, the processing up to the 48th is similarly performed. At that time, Rd is either 5.10 or 3.16 at the position of the adjustment optical sensor.

FIG. 30 is a schematic diagram illustrating an example of the positional relationship between the light emitting unit 111 and the adjustment optical sensor in accordance with the correspondence table of FIGS. In FIG. 30, the light emitting unit 111 (second light emitting unit) in which the position of the adjustment optical sensor is Rd = 5.10 is filled with an oblique line pattern. For example, the light emitting unit 111 (1, 1, 1) and the light emitting unit 111 (1, 1, 2) are the second light emitting units. In FIG. 30, the light emitting unit 111 (third light emitting unit) where the position of the adjustment optical sensor is Rd = 3.16 is filled with a dot pattern. For example, the light emitting unit 111 (1, 1, 3) or the light emitting unit 111 (1, 1, 4) is the third light emitting unit.
As can be seen from FIG. 30, the second light emitting unit and the third light emitting unit are adjacent to each other. Therefore, even in the configuration of FIG. 27, the luminance on the front surface of the optical sheet when all the light emitting units are turned on with the adjusted light emission luminance is canceled by the error of the light emission luminance between the light emitting units 111. Can be reduced.

19A and 19B, one optical sensor 113 is arranged for four light emitting units 111. FIG. Next, a case where one optical sensor 113 is arranged for six light emitting units 111 will be described.
FIG. 31A is a schematic diagram illustrating an example of the configuration of the LED substrate 110 according to the present embodiment. In FIG. 31A, the LED substrate 110 has a total of six light emitting portions 111 of 2 rows × 3 columns. In each light emitting unit 111, four LED chips 112 are arranged at equal intervals. The backlight device according to the present embodiment can adjust the light emission luminance for each light emitting unit 111. Each LED substrate 110 is provided with one optical sensor 113. The optical sensor 113 is disposed at the center of the six light emitting units 111 (that is, the center of the LED substrate 110).

FIG. 31B is a schematic diagram illustrating an example of the arrangement of the LED substrate 110, the light emitting unit 111, and the optical sensor 113 when viewed from the front direction (color liquid crystal panel 105 side). The LED substrate 110 (1,1) is adjacent to the right side of the LED substrate 110 (1,1) disposed at the upper left corner, and the LED substrate 110 (2,1) is disposed below the LED substrate 110 (1,1). ) Are adjacent. The LED substrate 110 (2, 2) is adjacent to the right side of the LED substrate 110 (2, 1). As described above, the light source substrate 101 includes a total of four LED substrates 110 of 2 rows × 2 columns (a total of 24 light emitting units 111 of 4 rows × 6 columns).
The LED substrate 110 (1, 1) includes a light emitting unit 111 (1, 1, 1), a light emitting unit 111 (1, 1, 2), a light emitting unit 111 (1, 1, 3), and a light emitting unit 111 (1, 1). , 4), light emitting part 111 (1, 1, 5) and light emitting part 111 (1, 1, 6). The LED substrate 110 (1, 1) is provided with an optical sensor 113 (1, 1). The same applies to other LED substrates.

  FIG. 31C is a cross-sectional view illustrating an example of an arrangement relationship between the LED substrate 110 and the optical sheet 106. Each LED chip 112 is arranged at equal intervals. An interval between the LED chips 112 is set as an LED pitch 501. The optical sheet 106 is arranged in parallel with the LED substrate 110. A distance between the optical sheet 106 and the LED substrate 110 is a diffusion distance 500. Here, it is assumed that the diffusion distance 500 is 1.5 times the LED pitch 501. By setting the diffusion distance 500 to be equal to or greater than the LED pitch 501, the luminance unevenness after passing through the optical sheet 106 can be sufficiently reduced.

FIG. 32 is a correspondence table (correspondence table in the case of the configuration of FIG. 31B) showing an example of the processing order of the plurality of light emitting units 111 and the correspondence relationship between the light emitting units 111 and the adjustment optical sensors. The process described in the first embodiment (the process of acquiring the detection value and outputting it to the microcomputer 125) is performed 24 times, the same as the number of the light emitting units 111. In FIG. 32, only two LED substrates 110 (1, 1) and 110 (1, 2) are illustrated for simplicity. The correspondence between the light emitting unit 111 and the adjustment optical sensor in the LED substrates 110 (2, 1) and 110 (2, 2) is the same as that of the LED substrates 110 (1, 1) and 110 (1, 2).
In the first process, the light emitting unit 111 (1, 1, 1) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (1, 2) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (1, 2) is output to the microcomputer 125.
FIG. 33A is a schematic diagram showing a positional relationship between the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 2) when viewed from the front direction (color liquid crystal panel 105 side). . Instead of the optical sensor 113 closest to the light emitting unit 111 (1, 1, 1), the optical sensor 113 (1, 2) located relatively far from the light emitting unit 111 (1, 1, 1) is used. Since the vertical distance 510 is 1 time the LED pitch 501 and the horizontal distance 511 is 8 times the LED pitch 501, the light emission center of the light emitting unit 111 (1, 1, 1) and the optical sensor 113 are calculated from the three square theorem. It can be seen that the distance between (1, 2) is 8.06 times the LED pitch 501. Since the diffusion distance 500 is 1.5 times the LED pitch 501, the distance between the light emission center of the light emitting unit 111 (1, 1, 1) and the optical sensor 113 (1, 2) is 5. It can also be seen that it is 37 times (Rd = 5.37).

As shown in FIG. 32, in the second process, the light emitting units 111 (1, 1, 2) are turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (1, 2) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (1, 2) is output to the microcomputer 125.
FIG. 33B is a schematic diagram showing a positional relationship between the light emitting units 111 (1, 1, 2) and the optical sensors 113 (1, 2) when viewed from the front direction (color liquid crystal panel 105 side). . Instead of the optical sensor 113 closest to the light emitting unit 111 (1, 1, 2), the optical sensor 113 (1, 2) located relatively far from the light emitting unit 111 (1, 1, 2) is used. Since the vertical distance 520 is 1 time the LED pitch 501 and the horizontal distance 521 is 6 times the LED pitch 501, the light emission center of the light emitting unit 111 (1, 1, 2) and the optical sensor 113 are calculated from the three square theorem. It can be seen that the distance between (1, 2) is 6.08 times the LED pitch 501. Since the diffusion distance 500 is 1.5 times the LED pitch 501, the distance between the light emission center of the light emitting unit 111 (1, 1, 2) and the optical sensor 113 (1, 2) is 4 of the diffusion distance 500. It can also be seen that it is 06 times (Rd = 4.06).

As shown in FIG. 32, in the third process, the light emitting unit 111 (1, 1, 3) is turned on and the other light emitting units 111 are turned off. Then, the optical sensor 113 (1, 2) is selected as the adjustment optical sensor, and the detection value of the optical sensor 113 (1, 2) is output to the microcomputer 125.
FIG. 33C is a schematic diagram showing a positional relationship between the light emitting units 111 (1, 1, 3) and the optical sensors 113 (1, 2) when viewed from the front direction (color liquid crystal panel 105 side). . Instead of the optical sensor 113 closest to the light emitting unit 111 (1, 1, 3), the optical sensor 113 (1, 2) located relatively far from the light emitting unit 111 (1, 1, 3) is used. Since the vertical distance 530 is 1 time the LED pitch 501 and the horizontal distance 531 is 4 times the LED pitch 501, the light emission center of the light emitting unit 111 (1, 1, 3) and the optical sensor 113 are calculated from the three square theorem. It can be seen that the distance between (1, 2) is 4.12 times the LED pitch 501. Since the diffusion distance 500 is 1.5 times the LED pitch 501, the distance between the light emission center of the light emitting unit 111 (1, 1, 3) and the optical sensor 113 (1, 2) is 2 of the diffusion distance 500. It can also be seen that it is 75 times (Rd = 2.75).

The fourth and subsequent processes are performed in the same manner in the order shown in the correspondence table of FIG. At this time, the distance between the light emission center of the light emitting unit 111 to be processed and the adjustment optical sensor is 5.37 times, 4.06 times, or 2.75 times the diffusion distance 500.
As described above, at a position on the back surface of the optical sheet facing the position where Rd is approximately 4, the change in luminance due to the deflection of the optical sheet is substantially zero.
In the present embodiment, the plurality of light emitting units include a first light emitting unit, a second light emitting unit, and a third light emitting unit. And the optical sensor detection part used when adjusting the light emission luminance of the first light emitting unit is an optical sheet whose change amount of luminance due to the deflection of the optical sheet when only the first light emitting unit is turned on is substantially zero. It is provided to face the position on the back. The detection unit used when adjusting the light emission luminance of the second light emitting unit and the detection unit used when adjusting the light emission luminance of the third light emitting unit are as described above.

  FIG. 34 is a schematic diagram illustrating an example of a positional relationship between the light emitting unit 111 and the adjustment optical sensor. In FIG. 34, the light-emitting portion (second light-emitting portion) where the position of the adjustment optical sensor is Rd = 5.37 is filled with a hatched pattern. For example, the light emitting unit 111 (1, 1, 1) and the light emitting unit 111 (1, 2, 3) are the second light emitting units. The light emitting part (third light emitting part) where the position of the adjustment optical sensor is Rd = 2.75 is filled with a dot pattern. For example, the light emitting unit 111 (1, 1, 3) or the light emitting unit 111 (1, 2, 1) is the third light emitting unit. And the light emission part (1st light emission part) whose position of the optical sensor for adjustment is a position of Rd = 4.06 is not filled with the pattern. For example, the light emitting unit 111 (1, 1, 2) and the light emitting unit 111 (1, 2, 2) are the first light emitting units. In the present embodiment, the first light emitting unit, the second light emitting unit, and the third light emitting unit are dispersed so that the error of the adjusted light emission luminance due to the change in the luminance distribution on the back surface of the optical sheet is offset. Has been placed. Specifically, the first light emitting unit to the third light emitting unit are repeatedly arranged in the row direction in the order of the second light emitting unit, the first light emitting unit, and the third light emitting unit. In other words, the second light emitting unit and the third light emitting unit are adjacent to each other via the first light emitting unit.

FIG. 35 shows an example of the relationship between the amount of change in luminance on the back surface of the optical sheet 106 and Rd. The x axis in FIG. 35 represents Rd. The y-axis in FIG. 35 indicates the amount of change in luminance (luminance on the back surface of the optical sheet) due to deflection of the optical sheet, that is, the detection error of the optical sensor. A curve 200 indicates a detection error when the optical sheet 106 is bent in the minus direction. A curve 201 indicates a detection error when the optical sheet 106 is bent in the plus direction. The position opposite to the position where Rd is approximately 4 is the zero cross point.
When the optical sheet 106 bends in the minus direction, a positive error (an error with a small absolute value) occurs at a position opposite to the position where Rd = 2.75, as indicated by a point 540. At a position opposite to the position of Rd = 4.06, the error is substantially zero as indicated by a point 541. At a position opposite to the position of Rd = 5.37, a negative error (an error with a small absolute value) occurs as indicated by a point 542.
In the present embodiment, since the first to third light emitting units are arranged in a distributed manner, the error in the light emission luminance of each light emitting unit due to the detection error of the adjustment optical sensor is offset. For example, an error in light emission luminance caused by a detection error occurring at a position where Rd = 2.75 and an error in light emission luminance caused by a detection error occurring at a position where Rd = 5.37 are offset. As a result, an error in luminance (luminance on the front surface of the optical sheet) when all the light emitting units are turned on with the adjusted emission luminance can be reduced.

  As described above, according to the present embodiment, the number of photosensors can be reduced, and luminance errors on the front surface of the optical sheet when all the light emitting units are turned on with the adjusted light emission luminance are reduced. can do.

  Note that one light source device may be configured by combining a plurality of different light source devices described in each embodiment.

Reference Signs List 101 light source substrate 106 optical sheet 111 light emitting unit 113 optical sensor 125 microcomputer

Claims (19)

A plurality of light emitting units;
An optical sheet that reflects part of the light from each of the plurality of light emitting units;
A plurality of detection units for detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on,
Adjusting means for adjusting the light emission luminance of the target light emitting unit based on the detection value of the detecting unit selected from the plurality of detecting units;
Have
The optical sheet includes a first portion in which luminance on the surface of the optical sheet when the light emitting unit of the target is turned on is substantially constant without depending on a deflection amount of the optical sheet, and light emission of the target There is a second part in which the brightness on the surface of the optical sheet when the part is lit changes depending on the amount of deflection of the optical sheet,
The light source apparatus according to claim 1 , wherein the adjustment unit selects a detection unit provided at a position corresponding to the first portion .   The optical sheet includes a first change portion that is a second portion in which the luminance on the surface of the optical sheet increases due to the deflection of the optical sheet approaching the target light emitting portion, and the optical sheet is the target light emitting portion. There is a second change portion that is a second portion in which the brightness on the surface of the optical sheet is reduced by the deflection approaching
  The first part is a boundary part between the first change part and the second change part.
The light source device according to claim 1.   In the first change portion, the brightness on the surface of the optical sheet decreases due to the deflection of the optical sheet away from the target light emitting unit,
  In the second change part, the brightness on the surface of the optical sheet increases due to the deflection of the optical sheet away from the target light emitting unit.
The light source device according to claim 2. A plurality of light emitting units;
An optical sheet that reflects part of the light from each of the plurality of light emitting units;
A plurality of detection units for detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on,
Adjusting means for adjusting the light emission luminance of the target light emitting unit based on the detection value of the detecting unit selected from the plurality of detecting units;
Have
When the target light emitting unit is turned on, the plurality of detection units are provided at positions where an error of a detection value due to the deflection of the optical sheet is not more than a predetermined value without depending on the deflection amount of the optical sheet. And a second detection unit provided at a position where an error of a detection value due to the deflection of the optical sheet is larger than the predetermined value depending on the deflection amount of the optical sheet. Including
The light source device, wherein the adjustment unit selects the first detection unit . A plurality of light emitting units;
An optical sheet that reflects part of the light from each of the plurality of light emitting units;
A plurality of detection units for detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on,
Adjusting means for adjusting the light emission luminance of the target light emitting unit based on the detection value of the detecting unit selected from the plurality of detecting units;
Have
The plurality of detection units include a first detection unit provided at a position where a detection value when the light emitting unit of the target is turned on is substantially constant without depending on a deflection amount of the optical sheet, and the target And a second detection unit provided at a position where a detection value when the light emitting unit is turned on varies depending on the amount of deflection of the optical sheet,
The light source device, wherein the adjustment unit selects the first detection unit . The detector which is selected by the adjustment means, the light source device according to any one of claims 1 to 5, characterized in that not the closest detector to the light-emitting portion of the subject. The adjustment unit selects a detection unit closest to a position where the amount of change due to deflection of the optical sheet is substantially zero when the target light emitting unit is turned on. The light source device according to any one of claims 1 to 3 . It said adjustment means, according to claim 3 or and selects the closest detection unit change amount of deflection of the optical sheet of the detected value at the position is substantially zero at the time when allowed to turn on the light-emitting portion of the object 5. The light source device according to 4 . The detection unit selected by the adjustment unit is provided at a position away from the light emission center of the target light emission unit by a distance of 2.75 to 5.37 times the distance between the light emission unit and the optical sheet. the light source device according to any one of claims 1 to 8, characterized in that is. The adjusting means is provided at a position away from the light emission center of the target light emitting unit by a distance shorter than 2.75 times or longer than 5.37 times the distance between the light emitting unit and the optical sheet. not selecting a detection portion is a light source device according to any one of claims 1 to 9, characterized in. The detection unit selected by the adjusting unit is provided at a position separated from the light emission center of the target light emission unit by a distance approximately four times the distance between the light emission unit and the optical sheet. The light source device according to any one of claims 1 to 10 . The plurality of light emitting units are turned on one by one,
It said adjusting means includes a light source device according to any one of claims 1 to 11, characterized by selecting one of the detector corresponding to one light emitting unit that is lighted. The optical sheet includes a light source device according to any one of claims 1, characterized in that deflect the heat to 12. The light source device according to any one of claims 1 to 13, wherein the plurality of light emitting units are arranged on a light source substrate substantially parallel to the optical sheet. Wherein the light emitting portion, a light source device according to any one of claims 1, wherein a plurality of light sources are provided to 14. The light source device according to any one of claims 1 to 15 ,
A liquid crystal panel for receiving light from the light source device from the back side;
A display device comprising: A plurality of light emitting units, an optical sheet that reflects a part of the light from each of the plurality of light emitting units, and a plurality that detects reflected light reflected by the optical sheet when the target light emitting unit is turned on. A light source device control method comprising:
A lighting step of lighting the plurality of light emitting units one by one;
A detection step of detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on by the lighting step, by a detection unit selected from the plurality of detection units;
An adjustment step of adjusting the light emission luminance of the target light emitting unit based on the detection value of the detection unit selected in the detection step;
Have
The optical sheet includes a first portion in which luminance on the surface of the optical sheet when the light emitting unit of the target is turned on is substantially constant without depending on a deflection amount of the optical sheet, and light emission of the target There is a second part in which the brightness on the surface of the optical sheet when the part is lit changes depending on the amount of deflection of the optical sheet,
In the detection step, a detection unit provided at a position corresponding to the first portion is selected. A plurality of light emitting units, an optical sheet that reflects a part of the light from each of the plurality of light emitting units, and a plurality that detects reflected light reflected by the optical sheet when the target light emitting unit is turned on. A light source device control method comprising:
A lighting step of lighting the plurality of light emitting units one by one;
A detection step of detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on by the lighting step, by a detection unit selected from the plurality of detection units;
An adjustment step of adjusting the light emission luminance of the target light emitting unit based on the detection value of the detection unit selected in the detection step;
Have
When the target light emitting unit is turned on, the plurality of detection units are provided at positions where an error of a detection value due to the deflection of the optical sheet is not more than a predetermined value without depending on the deflection amount of the optical sheet. And a first detection unit provided at a position where an error of a detection value due to the deflection of the optical sheet is larger than the predetermined value depending on a deflection amount of the optical sheet.
2 detectors,
In the detection step, the first detection unit is selected. A plurality of light emitting units, an optical sheet that reflects a part of the light from each of the plurality of light emitting units, and a plurality that detects reflected light reflected by the optical sheet when the target light emitting unit is turned on. A light source device control method comprising:
A lighting step of lighting the plurality of light emitting units one by one;
A detection step of detecting reflected light reflected by the optical sheet when the target light emitting unit is turned on by the lighting step, by a detection unit selected from the plurality of detection units;
An adjustment step of adjusting the light emission luminance of the target light emitting unit based on the detection value of the detection unit selected in the detection step;
Have
The plurality of detection units include a first detection unit provided at a position where a detection value when the light emitting unit of the target is turned on is substantially constant without depending on a deflection amount of the optical sheet, and the target And a second detection unit provided at a position where a detection value when the light emitting unit is turned on varies depending on the amount of deflection of the optical sheet,
In the detection step, the first detection unit is selected.

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