Luminance adjustment apparatus, luminance adjustment method, and program for functioning computer as luminance adjustment apparatus

Abstract

To provide a luminance adjustment apparatus which shortens a creation time of correction data.SOLUTION: A control device 103 of a luminance adjustment apparatus 100 includes an imaging control unit 411, an image processing unit 413, a parameter setting unit 417, and a drive control unit 412. The image processing unit 413 includes an image memory section 414, a luminance correction section 415, and an arithmetic section 416. The arithmetic section 416 calculates lightness of each light source 151 from image data, uses information set by the parameter setting unit 417 to select correction data stored in the luminance correction section 415, multiplies the lightness of each light source 151 and the selected correction data, calculates a ratio between the multiplied lightness of each light source 151 and desired lightness, and calculates an ideal drive current value of each light source 151 as an amount to be adjusted for each light source 151 from the ratio. The drive control section 412 uses the calculated drive current value to adjust lightness of a display screen 142 of a display device 140 via a drive circuit section 143.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a technique for inspecting a display device, and more particularly to a technique for inspecting a display device by adjusting the luminance of the display device. [Background technology]

[0002] In a conventional brightness adjustment device, when adjusting the distribution of brightness, correction data for correcting image data captured by a camera is created in advance. For example, Japanese Patent Application Laid-Open No. 2011-2401 (Patent Document 1) discloses a technology for "creating high-precision correction data in a brightness measurement device without using an expensive surface light source." This technology is a "method of calculating a correction coefficient in a brightness measurement device having an image sensor with a plurality of pixels," which includes "a step of capturing an image of an object at a reference position, a step of capturing an image of the object shifted by at least one pixel from the reference position, a sensitivity ratio calculation step of calculating a sensitivity ratio for each pixel with respect to a predetermined reference pixel based on the captured image, and a sensitivity correction coefficient calculation step of calculating a sensitivity correction coefficient for each pixel based on the sensitivity ratio" (see [Abstract]). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-2401 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the brightness adjustment device disclosed in Patent Document 1 captures an object to be inspected while shifting the camera pixel by pixel, and calculates a sensitivity correction coefficient for each pixel of the camera after capturing images the number of times the camera is shifted. Therefore, it takes time to create the correction data.

[0005] In addition, since the object is a two-dimensional display device, pixels other than those on the optical axis of the camera capture luminance from an oblique angle. Therefore, when a directional light source that is not standard diffusion captures an object, the luminance of the object other than the part on the optical axis is different from the luminance of the part from directly in front of it. To address this problem, there is a method of taking an image at an angle close to directly in front by increasing the measurement distance. However, adopting such a method causes a problem that the luminance adjustment device becomes large.

[0006] The present disclosure has been made in view of the above-mentioned background, and an object of the present disclosure in a certain aspect is to provide a technique for shortening the time required for creating correction data. Another object is to provide a smaller brightness adjustment device. [Means for solving the problem]

[0007] According to one embodiment, there is provided a luminance adjustment device, which includes: an imaging means for imaging a display surface on which a plurality of directional light sources are arranged; a memory unit storing correction data corresponding to the deviation angle, which is derived in advance from a distribution of luminance based on image data obtained by previously imaging a display device having the display surface, and a desired luminance previously defined for the display surface, in order to correct the luminance in accordance with a deviation angle from an optical axis of the imaging means; a calculation unit for calculating a corrected luminance for the display surface based on the correction data corresponding to the deviation angle; and a drive control unit for controlling the drive of the plurality of light sources based on a difference between the desired luminance and the corrected luminance.

[0008] In one aspect, by multiplying captured image data by correction data corresponding to the viewing angle characteristics of the display device, it is possible to correct deviations due to a measurement system and adjust the luminance distribution to a desired one.

[0009] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a hardware configuration of a brightness adjusting device 100 according to a first embodiment. [Diagram 2] FIG. 1 is a diagram showing the configuration of a display device 140. [Diagram 3] 1 is a diagram for explaining the relationship between each of a plurality of light sources 151 arranged in a substantially matrix shape and luminance. [Figure 4] FIG. 2 is a block diagram showing the configuration of a control device 103. [Diagram 5] 1 is a diagram illustrating a measurement system for measuring the viewing angle characteristics of luminance of an arbitrary display device 140. FIG. [Figure 6] FIG. 13 is a diagram showing an example of the viewing angle characteristic of luminance. [Figure 7] FIG. 7 is a diagram showing the reciprocal of the approximation curve shown in FIG. 6. [Figure 8] 1 is a diagram showing the distribution of luminance for a plurality of light sources 151 arranged in a substantially matrix shape. [Figure 9] FIG. 11 shows a configuration of a brightness adjusting device 900 according to a second embodiment. [Figure 10] 6 is a diagram showing an example of the viewing angle characteristic of luminance for a highly directional light source 151 of a display device 140 measured by the measurement system of FIG. 5. FIG. [Figure 11] 13 is a diagram showing the distribution of luminance in the left half region of display surface 142 of display device 140. FIG. [Figure 12] 13 is a diagram showing the distribution of luminance in the right half region of display surface 142 of display device 140. FIG. [Figure 13] FIG. 11 is a diagram showing the reciprocal of the approximation curve in FIG. 10. [Figure 14] 1 is a diagram showing a distribution obtained by combining the luminance of a plurality of light sources 151 arranged in a substantially matrix shape. [Figure 15] FIG. 15 illustrates an example of the configuration of a brightness adjusting device 1500. [Figure 16] FIG. 15 is a block diagram showing the configuration of a control device 1503. [Figure 17]1 is a diagram showing an example of images obtained by cameras 1510 and 1520 capturing images of display device 140 in which camera 110 has adjusted each light source 151 on display surface 142 of display device 140 to have uniform brightness. [Figure 18] FIG. 13 is a diagram illustrating an image after shape and size conversion. [Figure 19] FIG. 13 is a diagram showing the distribution of luminance after the shape of an image is transformed. [Figure 20] 13 is a diagram showing an example of a display device 140 having a portion of a display surface 142 where a light source 151p is mounted inclined to the left. [Figure 21] FIG. 2 is a block diagram showing the hardware configuration of a computer 2100 that functions as the control device 103, 1503. [Figure 22] 1 is a flowchart showing a part of the processing executed by a CPU 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0012] Embodiment 1 The configuration of brightness adjusting device 100 will be described with reference to Fig. 1. Fig. 1 is a block diagram showing a hardware configuration of brightness adjusting device 100 according to the first embodiment. Brightness adjusting device 100 accommodates display device 140 as an object to be inspected.

[0013] The brightness adjusting device 100 includes a housing 101, a control device 103, a camera 110, a camera fixing jig 121, and a receiving stand 122. The display device 140 is disposed at a predetermined position on the receiving stand 122. The display device 140 includes a display surface 142, a drive circuit unit 143, and a plurality of light sources 151. Each of the plurality of light sources 151 emits light 152.

[0014] The control device 103 controls the operation of the brightness adjusting device 100 . Camera 110 includes a plurality of image capturing elements 120 each having a red, green, and blue (RGB) color filter. Camera 110 is disposed at a position spaced a distance D from display surface 142 of display device 140 in the vertical direction.

[0015] The camera fixing jig 121 fixes the position of the camera 110. In one aspect, the camera fixing jig 121 is attached to the upper surface of the housing 101. The receiving stand 122 is attached to the lower surface of the housing 101. The housing 101 blocks light from the outside. The inner wall of the housing 101 is blackened to prevent stray light caused by reflection of the light 152 emitted from the display device 140 inside the housing 101.

[0016] The camera 110 captures light emitted from a plurality of light sources 151 to obtain a luminance distribution. The camera 110 outputs a signal corresponding to the captured image. The output signal is input to the control device 103.

[0017] 2 is a diagram showing the configuration of display device 140. Display device 140 includes a display cover 141, a display surface 142 that emits light, and a drive circuit unit 143. A plurality of light sources 151 are arranged vertically and horizontally on the surface of display surface 142. Each light source 151 is realized by, for example, an LED (Light Emitting Diode) or other directional element.

[0018] The drive circuit section 143 has a function of individually controlling the current that drives each of the plurality of light sources 151 , and sets the brightness of the display surface 142 .

[0019] [Luminance distribution] The relationship between the position and brightness of each of the plurality of light sources 151 will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining the relationship between the brightness of each of the plurality of light sources 151 arranged in a substantially matrix shape.

[0020] More specifically, FIG. 3(A) shows a schematic representation of an image obtained by photographing the display surface 142. FIG. 3(B) shows the distribution of luminance between an arbitrary line A'-A" in the image. As is clear from FIG. 3(B), the luminance in the periphery tends to be darker than the luminance in the center. Since each light source 151 arranged in the periphery is away from the position where the optical axis 150 of the camera 110 and the display surface 142 intersect, the diagonal component of the light 152 emitted from the light source 151 is captured by the camera 110. The light 152 has directionality. Therefore, as shown in FIG. 1, the light 152 is strong in the direction perpendicular to the display surface 142, and the diagonal component is relatively weak. As a result, the luminance in the periphery of the display device 140 is measured as dark, and the shorter the distance D, the larger the angle between the optical axis 150 and the line connecting the camera 110 and the light source 151 in the periphery becomes, so the difference between light and dark in luminance becomes more noticeable.

[0021] [Control device] The control device 103 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing the configuration of the control device 103. The control device 103 is realized, for example, by a personal computer that reads and executes a program.

[0022] The control device 103 includes an imaging control unit 411, an image processing unit 413, a parameter setting unit 417, and a drive control unit 412. The image processing unit 413 includes an image memory unit 414, a luminance correction unit 415, and a calculation unit 416.

[0023] The imaging control unit 411 controls the operation of the camera 110. The drive control unit 412 controls the operation of the display device 140. The image processing unit 413 processes the image signal output from the camera 110. The parameter setting unit 417 holds measurement conditions, desired luminance information of each object, etc. The measurement conditions, luminance information, etc. are input by the user of the luminance adjustment device 100.

[0024] In the image processing unit 413, the image memory unit 414 temporarily stores image data such as a measurement image. The brightness correction unit 415 stores correction data for correcting the measurement image. The correction data is acquired in advance for each object. The calculation unit 416 performs a preset image processing calculation on the measurement image stored in the image memory unit 414.

[0025] In one aspect, drive control unit 412 causes display surface 142 to execute a pre-specified display via drive circuit unit 143 of display device 140. In accordance with the control of drive control unit 412, imaging control unit 411 controls camera 110 to capture an image of display surface 142. Image data acquired by camera 110 is input to control device 103. The image data is stored in image memory unit 414.

[0026] The calculation unit 416 calculates the brightness of each light source 151 from the image data. The calculation unit 416 selects correction data stored in the brightness correction unit 415 using information set by the parameter setting unit 417. Furthermore, the calculation unit 416 multiplies the brightness of each light source 151 by the selected correction data. The calculation unit 416 calculates the ratio between the brightness of each light source 151 after multiplication and a desired brightness, and calculates the amount to be adjusted for each light source 151, that is, the ideal drive current value of each light source 151, from the ratio. The drive control unit 412 adjusts the brightness of the display surface 142 of the display device 140 via the drive circuit unit 143 using the drive current value calculated in the image processing unit 413.

[0027] [Creating correction data] A method for acquiring the correction data will be described with reference to Fig. 5. Fig. 5 is a diagram illustrating a measurement system for measuring the viewing angle characteristic of luminance of an arbitrary display device 140.

[0028] The distance from the display surface 142 of the display device 140 to the luminance meter 105, that is, the measurement distance D', is adjusted to the distance D from the display surface 142 to the camera 110. First, the user (operator) of the luminance adjustment device measures the luminance of the light source 151a from directly in front, that is, the luminance of the display surface 142 emitting the light 152a from the optical axis direction of the light source 151a. Then, the user rotates the luminance meter 105 in the left-right and up-down directions with the light source 151a as a reference, and measures the luminance when the optical axis is shifted from directly in front. Note that, although a configuration in which the display device 140 is fixed and the luminance meter 105 is rotated is exemplified in FIG. 5, the configuration is not limited to this. A luminance adjustment device according to another aspect may have a configuration in which the luminance meter 105 is fixed and the display device 140 is rotated with the light source 151a as a reference.

[0029] [Luminance viewing angle characteristics] The viewing angle characteristic of luminance will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a diagram showing an example of the viewing angle characteristic of luminance. The horizontal axis is angle θ, which represents the deviation from the optical axis. The vertical axis is luminance L, which represents a relative value when the luminance at 0 degrees on the optical axis is set to 1. As shown in Fig. 6, as the angle increases around the optical axis of 0 degrees, the luminance L decreases. Note that the dotted line is an approximation curve.

[0030] Fig. 7 is a diagram showing the reciprocal of the approximation curve shown in Fig. 6. The function f(θ) for deriving the correction data is expressed as a function with the angle θ as a parameter. The calculation unit 416 derives the correction data using the function, and stores the derived correction data in the brightness correction unit 415.

[0031] In another aspect, the luminance adjusting device 100 holds, for each of the plurality of display devices 140, the viewing angle characteristic of each device and a function f(θ) for deriving correction data. When a plurality of display devices are to be inspected, the user measures the viewing angle characteristic of luminance for each display device 140 in advance, and stores the corresponding correction data (f(θ)) in the luminance correction unit 415. The calculation unit 416 selects the correction data corresponding to the display device from among the correction data stored in the luminance correction unit 415, based on the information set in the parameter setting unit 417.

[0032] In the measurement system of the brightness adjusting device 100, the coordinates (x, y) and the angle θ have the relationship shown in the following formula (1). θ=arcsin(√(x 2 +y 2 ) / D) ···(1) In one aspect, calculation unit 416 converts the central coordinates of each light source 151 into an angle from equation (1), reads out function f(θ) for deriving correction data stored in luminance correction unit 415, and multiplies the value at the corresponding angle. Luminance adjustment device 100 can correct the luminance distribution obtained by calculating the brightness of each light source 151 from the image data stored in image memory unit 414.

[0033] [Brightness distribution after correction] The distribution of luminance after correction will be described with reference to FIG. 8. FIG. 8 is a diagram showing the distribution of luminance for a plurality of light sources 151 arranged in a matrix. More specifically, FIG. 8(A) shows the distribution of luminance after multiplying the distribution of luminance in FIG. 3(B) by the correction data stored in the luminance correction unit 415. In order to make the brightness of the display device 140 a desired brightness, for example, a uniform brightness, the calculation unit 416 compares the brightness after correction with the desired brightness for each light source 151 and calculates the adjustment amount of the drive current. The drive control unit 412 changes the drive current of each light source 151 via the drive circuit unit 143 to adjust the brightness of the display surface 142.

[0034] Fig. 8(B) shows the distribution of luminance after the brightness adjustment. As shown in Fig. 8(B), the luminance value of each light source 151 is uniform.

[0035] As described above, the brightness adjusting device 100 according to the present embodiment can adjust the brightness distribution of the display surface 142 of the display device 140 to a desired distribution by performing correction taking into account the influence of the measurement system.

[0036] Note that the present embodiment illustrates a case where correction data is created in advance for a light source of one color of display device 140. When a display device according to another aspect has a light source configured with multiple colors such as RGB, the luminance adjustment device can measure the viewing angle characteristics of luminance for each color and create correction data for each color.

[0037] Embodiment 2 The following describes the second embodiment. The brightness adjustment device according to the present embodiment differs from the brightness adjustment device according to the first embodiment in that it has a function of moving camera 110 in the horizontal direction. Note that the same components as those in brightness adjustment device 100 according to the first embodiment are given the same numbers. Therefore, the description of the same components will not be repeated.

[0038] A luminance adjusting device 900 according to the present embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram showing a configuration of a luminance adjusting device 900 according to a second embodiment. The luminance adjusting device 900 further includes a moving stage 926 in addition to the configuration of the luminance adjusting device 100. The moving stage 926 moves the camera 110 horizontally in the longitudinal direction relative to the display surface 142.

[0039] Fig. 10 is a diagram showing an example of the viewing angle characteristic of luminance for highly directional light source 151 of display device 140 measured by the measurement system of Fig. 5. The viewing angle characteristic shown in Fig. 10 shows that luminance L varies greatly as angle θ increases, compared to the viewing angle characteristic shown in Fig. 6. The correlation between the approximation curve for such characteristics and angle θ tends to be low, and therefore the reliability of the correction data is low.

[0040] Therefore, the brightness adjustment device 900 according to the present embodiment divides the imaging range and synthesizes the brightness for each range to generate correction data. Note that the dotted line shown in Fig. 10 is an approximation curve that approximates within the range of capture angles when the imaging range is divided into two.

[0041] Referring again to FIG. 9, the brightness adjustment device 900 drives the moving stage 926 to move the camera 110 so that the optical axis 150 of the camera 110 coincides with the center position of the left half area of ​​the display surface 142 of the display device 140. After the camera 110 stops, the brightness adjustment device 900 captures each light source 151 emitting light and acquires captured image data for obtaining a luminance distribution. Next, the brightness adjustment device 900 moves the camera 110 by the moving stage 926 so that the optical axis 150 of the camera 110 coincides with the center position of the right half area of ​​the display surface 142 of the display device 140, thereby capturing an image of the luminance distribution of the light source 151. In this way, the brightness adjustment device 900 divides the range captured by the camera 110 with respect to the display surface 142 into two, thereby reducing the effective capture angle for the camera 110.

[0042] [Luminance distribution] The relationship between the position and luminance of each of the plurality of light sources 151 will be described with reference to Fig. 11 to Fig. 13. Fig. 11 is a diagram showing the distribution of luminance in the left half region of the display surface 142 of the display device 140.

[0043] More specifically, FIG. 11(A) is an example of an image measured by moving camera 110 so that optical axis 150 of camera 110 coincides with the center position of the left half area of ​​display surface 142 of display device 140. FIG. 11(B) shows the distribution of luminance between an arbitrary line B'-B". The right side area of ​​display surface 142 (dotted frame in FIG. 11(A)) is outside the effective range.

[0044] FIG. 12 is a diagram showing the distribution of luminance in the right half region of display surface 142 of display device 140. FIG. 12(A) is an example of an image measured by moving camera 110 so that optical axis 150 of camera 110 coincides with the center position of the right half region of display surface 142 of display device 140. FIG. 12(B) shows the distribution of luminance between an arbitrary line C'-C". The left region of display surface 142 (dotted frame in FIG. 12(A)) is also outside the effective range.

[0045] Fig. 13 is a diagram showing the reciprocal of the approximation curve in Fig. 10. The function f(θ) for deriving the correction data is expressed as a function with the angle θ as a parameter. The calculation unit 416 derives the correction data using the function f(θ) and stores the derived correction data in the brightness correction unit 415.

[0046] [Brightness distribution after correction] The luminance distribution after correction will be described with reference to FIG. 14. FIG. 14 is a diagram showing a distribution obtained by combining the luminance of a plurality of light sources 151 arranged in a matrix. More specifically, FIG. 14(A) shows a luminance distribution obtained by combining the luminance distribution shown in FIG. 11(B) and the luminance distribution shown in FIG. 12(B) after multiplying the luminance distribution by the correction data stored in the luminance correction unit 415. The calculation unit 416 compares the luminance after correction with the desired luminance (here, uniform luminance) for each light source 151 to calculate the adjustment amount of the drive current. The drive control unit 412 changes the drive current of each light source 151 via the drive circuit unit 143 to adjust the luminance of the display surface 142.

[0047] Fig. 14B shows the distribution of luminance after adjustment. As shown in Fig. 14B, the luminance values ​​of the light sources are uniform.

[0048] In this manner, brightness adjustment device 900 according to the present embodiment divides the area to be photographed of display device 140 and measures each area. In this manner, brightness adjustment device 900 corrects the distribution of brightness on display surface 142 taking into account the influence of the measurement system, without increasing the effective capture angle of camera 110. This allows adjustment to a desired distribution.

[0049] In addition, in another aspect, the configuration adopted by the brightness adjustment device 900 is also effective in cases where there is a restriction on the height of the device, such as when the brightness adjustment device 900 cannot adopt a sufficient height, instead of the restriction on the size of the display device 140.

[0050] Embodiment 3 The third embodiment will be described below. The brightness adjustment device 1500 according to the present embodiment differs from the brightness adjustment devices 100 and 900 according to the above-described embodiments in that the brightness adjustment device 1500 includes cameras 1510 and 1520 that image the display device 140 from diagonally above the display device 140, in addition to the camera 110 that images the display device 140 from above. Note that the same components as those included in the brightness adjustment devices 100 and 900 are denoted by the same numbers. Therefore, the description of the same components will not be repeated.

[0051] A brightness adjusting device 1500 according to the present embodiment will be described with reference to Fig. 15. Fig. 15 is a diagram illustrating a configuration of the brightness adjusting device 1500.

[0052] Brightness adjusting device 1500 includes cameras 1510 and 1520, and fixing jigs 1511 and 1521 for fixing cameras 1510 and 1520, respectively, in addition to the configuration of brightness adjusting device 100. Camera 1510 includes an image sensor 1512. Camera 1520 includes an image sensor 1522. Furthermore, brightness adjusting device 1500 includes a control device 1503 instead of control device 103.

[0053] In one aspect, brightness adjusting device 1500 uses camera 110 arranged perpendicular to display surface 142 of display device 140, camera 1510 arranged diagonally above left with respect to display surface 142, and camera 1520 arranged diagonally above right with respect to display surface 142 to capture images of display surface 142 and obtain image data for obtaining a distribution of brightness of light emitted from multiple light sources 151. Cameras 110, 1510, and 1520 output signals corresponding to the captured images. Each output signal is input to control device 1503.

[0054] [Control device] The control device 1503 will be described with reference to FIG. 16. FIG. 16 is a block diagram showing the configuration of the control device 1503. The control device 1503 according to this embodiment includes an image processing unit 1613 instead of the image processing unit 413 in the configuration of the control device 103 according to the first embodiment. The image processing unit 1613 further includes an image shape conversion unit 1620 and a brightness unevenness reference unit 1630 in addition to the configuration of the image processing unit 413. The image shape conversion unit 1620 converts the shape of the captured measurement image. The brightness unevenness reference unit 1630 holds one or more thresholds that define the range of allowable brightness unevenness. The one or more thresholds may include an upper threshold and a lower threshold.

[0055] The operation of the image shape conversion unit 1620 will be described with reference to Fig. 17. Fig. 17 is an example of an image obtained by photographing the display device 140, which has been adjusted by the camera 110 so that each light source 151 of the display surface 142 of the display device 140 has a uniform brightness, with a camera disposed obliquely above the display device 140. More specifically, Fig. 17(A) shows an image obtained by photographing the display device 140, which has been adjusted so that each light source 151 has a uniform brightness, with the camera 1510. Fig. 17(B) shows an image obtained by photographing the display device 140, which has been adjusted so that each light source 151 has a uniform brightness, with the camera 1520.

[0056] 17(A) and 17(B), in order to capture the entire image in which the near side becomes larger, in brightness adjustment device 1500, cameras 1510 and 1520 are arranged so that distance D2 from the center of display surface 142 of display device 140 to camera 1510 and distance D3 from the center to camera 1520 are longer than distance D to camera 110. In another aspect, cameras 1510 and 1520 may be arranged at a distance equal to D by configuring the focal length of the lens attached to cameras 1510 and 1520 to be shorter than the focal length of the lens attached to camera 110 so that display device 140, which is the subject, can be captured at a wide angle.

[0057] The cameras 1510 and 1520 are disposed obliquely above the display surface 142 of the display device 140. Therefore, as shown in FIG. 17(A) and FIG. 17(B), the shape of the measured image of the camera 110 is different, that is, the measured image is a trapezoid rather than a rectangle. Furthermore, since the distance from the camera 110 to the front side of the display surface 142 and the distance from the camera 110 to the back side of the display surface 142 are different, the size of one pixel of the measured image differs depending on the position of the display surface 142. Therefore, it is difficult to calculate the luminance, which is the amount of light per unit area of ​​the light source 151, in this state. Therefore, the image shape conversion unit 1620 converts the image data so that the measured images of the cameras 1510 and 1520 have the same shape and size as the measured image of the camera 110. That is, the image shape conversion unit 1620 converts the trapezoid shape into a rectangular shape. As a result, the size of each pixel of the converted measured image becomes uniform.

[0058] Therefore, the image after conversion by image shape conversion unit 1620 will be described with reference to Fig. 18. Fig. 18 is a diagram that shows a schematic representation of an image after conversion of shape and size. More specifically, Fig. 18(A) shows an image after the shape of an image captured by camera 1510 has been converted. Fig. 18(B) shows an image after the shape of an image captured by camera 1520 has been converted.

[0059] A method for converting a trapezoidal image into a rectangular image includes, for example, detecting light sources at the four corners of an image, regarding the centers of gravity of the light sources as the vertices of the four corners, and performing an interpolation process on the distribution of luminance within the surface so that the coordinates of the vertices of the four corners match the coordinates of the center of gravity of the four corners of the target image, that is, the image of camera 110. However, the method for converting the shape is not limited to this.

[0060] Each image input to the control device 1503 is stored in the image memory unit 414. The image shape conversion unit 1620 compares the images from the cameras 1510 and 1520 with the image from the camera 110, converts the shapes of the images from the cameras 1510 and 1520 so that the vertices of the four corners match, and stores the images in the image memory unit 414.

[0061] The operation of the luminance unevenness reference unit 1630 will be described with reference to Fig. 19. Fig. 19 is a diagram showing the distribution of luminance after the shape of an image is converted. More specifically, Fig. 19(A) shows the distribution of luminance between an arbitrary line E'-E" in an image after the shape of an image captured by camera 1510 is converted. Fig. 19(B) shows the distribution of luminance between an arbitrary line F'-F" in an image after the shape of an image captured by camera 1520 is converted.

[0062] As shown in Figures 19(A) and 19(B), due to the influence of the directivity of the light source 151, there is a tendency for the brightness unevenness to have a gradation-like pattern, with the sides closer to the cameras 1510 and 1520 (the E' side and the F" side) being relatively brighter and the sides further away (the E" side and the F' side) being relatively darker. The brightness unevenness reference unit 1630 stores threshold line data that defines the allowable range of brightness unevenness taking this tendency into consideration. The calculation unit 416 selects the threshold line data based on the information set by the parameter setting unit 417.

[0063] FIG. 20 is an example of a display device 140 having a portion on the display surface 142 where the light source 151p is mounted tilted to the left. When the light source 151p is mounted tilted on the display surface 142, the light 152p emitted from the light source 151p is also tilted. Therefore, due to the influence of the directivity of the light source 151p, the light becomes strongest in a direction shifted to the left from the perpendicular direction to the display surface 142. In other words, the light in the perpendicular direction to the display surface 142 becomes weaker than the light emitted from the light source 151 mounted normally without tilting. Therefore, in this state, when the brightness adjustment device 1500 adjusts the brightness using an image acquired by the camera 110 arranged above the display device 140, the drive current for the tilted light source 151p is changed to be higher than the drive current supplied when the light source 151p is mounted normally. In other words, the drive current is adjusted so that the luminous flux of the light 152p emitted from the light source 151p itself becomes brighter.

[0064] Referring again to Fig. 19, in Fig. 19(A), the light source 151p at point P is above the upper limit of the threshold line of the luminance distribution, and is therefore detected as being brighter than the desired brightness. On the other hand, in Fig. 19(B), the light source 151p at point P is below the lower limit of the threshold line of the luminance distribution, and is therefore detected as being darker than the desired brightness. This state is the same as the state seen when the light source 151p is mounted tilted to the left, as shown in Fig. 20, and therefore can be detected as localized luminance unevenness by comparing with the threshold line.

[0065] In this manner, the brightness adjusting device 1500 according to the present embodiment measures the distribution of brightness on the display surface 142 of the display device 140 using image data acquired by photographing the display surface 142 with the cameras 1510 and 1520 provided obliquely above the display surface 142. In this manner, the brightness adjusting device 1500 can detect local brightness unevenness caused by factors such as when any of the multiple light sources 151 is mounted at an angle.

[0066] [Control device configuration] An example of a specific configuration of the control device 103, 1503 will be described with reference to Fig. 21. Fig. 21 is a block diagram showing the hardware configuration of a computer 2100 that functions as the control device 103, 1503.

[0067] The computer 2100 includes, as its main components, a CPU (Central Processing Unit) 1 that executes a program, a mouse 2 and a keyboard 3 that receive instructions input by a user of the computer 2100, a RAM 4 that volatilely stores data generated by the execution of the program by the CPU 1 or data input via the mouse 2 or keyboard 3, a hard disk 5 that nonvolatilely stores data, an optical disk drive 6, a communication interface (I / F) 7, and a monitor 8. The components are mutually connected by a data bus. A CD-ROM (Compact Disc - Read Only Memory) 9 or other optical disks are loaded into the optical disk drive 6.

[0068] The processing in the computer 2100 is realized by each piece of hardware and software executed by the CPU 1. Such software may be pre-stored in the hard disk 5. In addition, the software may be stored in a CD-ROM 9 or other recording medium and distributed as a computer program. Alternatively, the software may be provided as a downloadable application program by an information provider connected to the Internet. Such software is read from the recording medium by the optical disk drive 6 or other reading device, or downloaded via the communication interface 7, and then temporarily stored in the hard disk 5. The software is read from the hard disk 5 by the CPU 1 and stored in the RAM 4 in the form of an executable program. The CPU 1 executes the program.

[0069] Each component constituting the computer 2100 is a common one. Therefore, one of the essential parts of the technical idea according to the present disclosure can be said to be software stored in the RAM 4, the hard disk 5, the CD-ROM 9 or other recording medium, or software that can be downloaded via a network. The recording medium may include a non-transitory computer-readable data recording medium. The operation of each piece of hardware of the computer 2100 is well known, and therefore a detailed description will not be repeated.

[0070] The recording medium is not limited to a CD-ROM, a FD (Flexible Disk), or a hard disk, but may also be a medium that carries a program in a fixed manner, such as an SSD (Solid State Drive), a magnetic tape, an optical disk (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc)), an IC (Integrated Circuit) card (including a memory card), an optical card, a mask ROM, an EPROM (Electronically Programmable Read-Only Memory), an EEPROM (Electronically Erasable Programmable Read-Only Memory), or a semiconductor memory such as a flash ROM.

[0071] The program referred to here includes not only a program that can be directly executed by a CPU, but also a source program format program, a compressed program, an encrypted program, and the like.

[0072] The operation of the computer 2100 functioning as a brightness adjustment unit will be described with reference to Fig. 22. Fig. 22 is a flow chart showing a part of the processing executed by the CPU 1.

[0073] (1) In a certain aspect, CPU1 controls cameras 110, 1510, and 1520 to capture display surface 142 of display device 140 on which multiple light sources 151 having directivity are arranged (step S2210). Hard disk 5 stores correction data according to the deviation angle, which is derived in advance from a distribution of brightness based on image data obtained by previously capturing an image of display surface 142, and a desired brightness that is predefined for the display surface, in order to correct the brightness in accordance with the deviation angle from the optical axis of camera 110. CPU1 accesses the correction data and the desired brightness (step S2210). CPU1, as arithmetic unit 416, calculates the corrected brightness for the display surface based on the correction data according to the deviation angle (step S2230). CPU1, as drive control unit 412, controls driving of multiple light sources 151 based on the difference between the desired brightness and the corrected brightness (step S2240).

[0074] (2) In another aspect, the correction data is data obtained by taking the reciprocal of a characteristic distribution of viewing angle luminance for each of a plurality of light sources, the characteristic distribution being determined by using the angle between each of the plurality of light sources and optical axis 150 of camera 110 as a parameter.

[0075] (3) In another aspect, CPU 1 controls motion stage 926 which moves camera 110 longitudinally relative to display surface 142 .

[0076] (4) In another aspect, CPU 1 controls shooting by camera 110 as a first camera arranged in front of display surface 142, as well as camera 1510 as a second camera and camera 1520 as a third camera arranged obliquely with respect to display surface 142. CPU 1 receives image data output from each camera.

[0077] (5) In another aspect, CPU 1 functions as image shape conversion unit 1620 to convert the shape and size of the images captured by cameras 1510 and 1520 so that they have the same shape and size as the image captured by camera 110.

[0078] (6) In still another aspect, hard disk 5 stores, as brightness unevenness reference unit 1630, one or more thresholds for comparison with the distribution of brightness according to the converted data. The one or more thresholds may include, for example, an upper threshold and a lower threshold. CPU 1 uses the thresholds to detect the presence or absence of local brightness unevenness due to factors such as the inclination of light source 151.

[0079] As described above in detail, the brightness adjustment device according to this embodiment does not shift the camera in the longitudinal direction of the pixels, so that the time required to create correction data is shortened. Also, since correction data can be created taking into account the shift angle, there is no need to increase the distance between camera 110 and display device 140. This allows the brightness adjustment device to be made more compact.

[0080] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0081] 1 CPU, 2 mouse, 3 keyboard, 4 RAM, 5 hard disk, 6 optical disk drive, 7 communication interface, 8 monitor, 9 CD-ROM, 100, 900, 1500 brightness adjustment device, 101 housing, 103, 1503 control device, 105 brightness meter, 110, 1510, 1520 camera, 120, 1512, 1522 imaging element, 121 camera fixing jig, 122 unit, 140 display device, 141 display cover, 142 display surface, 143 drive circuit unit, 150 optical axis, 151, 151a, 151p light source, 152, 152p light, 411 imaging control unit, 412 drive control unit, 413, 1613 image processing unit, 414 image memory unit, 415 brightness correction unit, 416 calculation unit, 417 Parameter setting unit, 926 moving stage, 1511, 1521 fixing jig, 1620 image shape conversion unit, 1630 brightness unevenness reference unit, 2100 computer.

Claims

1. an imaging means for imaging a display surface on which a plurality of directional light sources are arranged; a storage unit that stores correction data corresponding to the deviation angle from the optical axis of the imaging means, the correction data being derived in advance from a distribution of brightness based on image data obtained by previously photographing a display device having the display screen, and a desired brightness that is previously defined for the display screen; and a calculation unit that calculates a corrected luminance for the display surface based on correction data corresponding to the deviation angle; a drive control unit that controls driving of the plurality of light sources based on a difference between the desired luminance and the corrected luminance.

2. 2. The brightness adjusting device according to claim 1, wherein the correction data is data obtained by taking the reciprocal of a characteristic distribution of viewing angle brightness for each of the plurality of light sources, the characteristic distribution being determined by using an angle between the light source and an optical axis of the imaging means as a parameter.

3. The brightness adjusting device according to claim 1 , further comprising a moving means for moving the imaging means in a longitudinal direction relative to the display surface.

4. The imaging means is A first camera disposed in front of the display surface; The brightness adjusting device according to claim 1 , further comprising: a second camera disposed obliquely with respect to the display surface.

5. The brightness adjusting device according to claim 4 , further comprising a conversion unit for converting a shape and a size of the image captured by the second camera so that the shape and the size of the image captured by the first camera are the same as those of the image captured by the first camera.

6. The brightness adjusting device according to claim 5 , further comprising a reference storage unit storing one or more threshold values ​​for comparison with a distribution of brightness according to the data converted by the conversion unit.

7. Taking an image of a display surface on which a plurality of directional light sources are arranged using a camera; accessing correction data corresponding to the deviation angle from the optical axis of the camera, the correction data being derived in advance from a distribution of brightness based on image data obtained by previously photographing a display device having the display surface, the correction data corresponding to the deviation angle from the optical axis of the camera, and a desired brightness that is previously defined for the display surface; calculating a corrected luminance for the display surface based on correction data corresponding to the deviation angle; and controlling driving of the plurality of light sources based on a difference between the desired luminance and the corrected luminance.

8. A program for causing a computer to function as a brightness adjustment device, the program including: Taking an image of a display surface on which a plurality of directional light sources are arranged using a camera; accessing correction data corresponding to the deviation angle from the optical axis of the camera, the correction data being derived in advance from a distribution of brightness based on image data obtained by previously photographing a display device having the display surface, the correction data corresponding to the deviation angle from the optical axis of the camera, and a desired brightness that is previously defined for the display surface; calculating a corrected luminance for the display surface based on correction data corresponding to the deviation angle; and controlling driving of the plurality of light sources based on a difference between the desired luminance and the corrected luminance.

Images