JP4652301B2 - Color display board image quality inspection method and image quality inspection apparatus - Google Patents

Description

  The present invention relates to an image quality inspection method and an image quality inspection apparatus for a color display panel such as a color liquid crystal display panel, and more particularly to inspection of luminance of a color display panel having a stripe arrangement in which pixels of the same color are continuous in a photographed image by a monochrome camera. The present invention relates to an image quality inspection method and an image quality inspection apparatus based on the image quality inspection method.

  Patent Document 1 describes an inspection method for determining whether or not a component is correctly mounted on a printed circuit board. In this inspection method, paying attention to the color difference between the printed circuit board and each component on the printed circuit board, the printed circuit board on which these components are mounted is photographed sequentially by a monochrome imaging means through each of a plurality of color filters. . By processing these monochrome images, it is possible to determine whether or not each component is placed at an appropriate position on the printed circuit board. Therefore, it is possible to determine whether or not the component mounting position is appropriate by simple image processing compared to color image processing. Can be efficiently determined.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for applying this determination method to an image quality inspection method for a color liquid crystal display panel (hereinafter simply referred to as LCD). According to the inspection method described in Patent Document 2, the LCD display screen is photographed sequentially with a monochrome CCD camera through color filters such as R, G, and B, and the brightness of the LCD is determined from the image. Defects can be inspected. Further, by providing the image quality correction means, the non-uniformity of the screen is eliminated, and the variation of the determination result based on this non-uniformity is prevented.

  By the way, in the image quality inspection, when the presence of a luminance defect is confirmed from the inspection image taken by the CCD camera as described above, the pixel address of the detected defect LCD is specified. In order to specify this address, the pixel address of the CCD camera is associated with the pixel address of the LCD in advance. For this correspondence, in order to eliminate the influence of aberration such as chromatic aberration due to each filter, the lighting screen is photographed through each color filter, and from the image of the CCD camera through each color filter, the CCD pixel address and An address correspondence table with the LCD pixel address is formed.

  As long as the relative position between the LCD to be inspected and the CCD camera is not shifted on the inspection stage, once the address correspondence table for the first LCD to be inspected is created, the second sheet of the same standard is used. Subsequent luminance defect pixel addresses for LCDs can be easily identified based on the address correspondence table described above.

  However, in order not to cause a substantial shift in the relative position between each LCD and the CCD camera, the inspection is performed so that all the electrodes of the drive circuit formed on the LCD are accurately in contact with the corresponding probes of the inspection apparatus. It is necessary to precisely position the receiving LCD on the inspection stage for each time, and this takes time for inspection.

  Therefore, a simple lighting method using a short circuit called a shorting bar is used for driving the LCD on the inspection stage. In this simple lighting system, the operation of the LCD pixels on the inspection stage can be appropriately controlled for inspection by bringing a very small number of probes into contact with the short circuit.

  However, when this simple lighting method is adopted, each LCD displays all the probes of the inspection apparatus on the inspection stage, regardless of whether all the pixels are lit or displayed partially. It is not necessary to make contact with all corresponding electrodes, only a few selected probes are placed in contact with the short circuit. Therefore, in the simple lighting method, it is substantially impossible to sequentially arrange the LCDs at appropriate predetermined positions on the inspection stage without causing a deviation from the CCD camera.

  Therefore, in the case of this simple lighting method, the luminance is obtained from each inspection image obtained by photographing the inspection screen through the R, G, B color filters with the monochrome photographing means in a state where all the pixels of the LCD are lit. The presence or absence of defects can be determined. However, in order to specify the LCD pixel address of the defective pixel, the following procedure is required for each LCD to be inspected.

  First, the first display screen of the LCD is photographed by the monochrome photographing means through the R, G, B color filters by the simple lighting method. In this case, in an LCD having a stripe-type pixel arrangement, it is difficult to accurately specify each address from an image in which all pixels are lit as in the inspection screen. For this reason, in an LCD having a stripe-type pixel arrangement, discontinuous pixels for each color are displayed in a dispersed manner in order to easily specify an accurate address.

  The above-described inspection screen and each first distributed display screen are imaged without moving the LCD that is the inspection target on the inspection stage. Therefore, the first correspondence between the pixel address of the CCD and the pixel address of the LCD is obtained from each first distributed display image obtained for each filter and the image on the inspection screen. When a defective pixel such as a luminance defect is observed in each CCD image that is an inspection image, the correspondence between the pixel address of the inspection screen (LCD) and the pixel address of each first distributed display screen (CCD) is represented. From the first correspondence relationship, a corresponding pixel address on the LCD is obtained and used for repairing a defective pixel of the LCD.

  As described above, according to the simple lighting method, although it is not necessary to place each LCD on the inspection stage with high accuracy, as described above, even in the inspection of the LCD of the same standard, the pixel of the LCD In order to associate the address with the pixel address of the CCD, the first dispersion of the color display plate is performed in a state where non-continuous pixels for each color are dispersedly displayed by the simple lighting method for each LCD to be inspected. The display screen needs to be photographed by the monochrome photographing means through the R, G, B color filters.

  Therefore, in the conventional inspection method using the simple lighting method, the corresponding address of the inspection image is obtained separately from the inspection image capturing every time the inspection image is detected to detect defective pixels such as luminance defects. Therefore, on the inspection stage, it is necessary to repeat the photographing three times through each RGB filter through the distributed display screen in the simple lighting method. Therefore, since the image inspection process becomes complicated, the conventional inspection method using the simple lighting method further simplifies the procedure for obtaining the corresponding address in order to further simplify the image inspection process. Was strongly desired.

JP-A-1-150844 Japanese Patent Laid-Open No. 9-43292

  Accordingly, an object of the present invention is to simplify the procedure for determining the image quality of the color display plate by simplifying the procedure for obtaining the correspondence between the pixel address of the color display plate and the pixel address of the photographing means. There is.

In the present invention, in a state where all the pixels of a color display panel having a stripe type pixel array are turned on by a simple lighting method using a short circuit, the inspection screen is photographed by a monochrome photographing means through R, G, and B color filters. A method of inspecting the image quality of the color display board from each inspection image obtained
In a state where discontinuous pixels for each color are dispersedly displayed by the simple lighting method, the first dispersion display screen of the color display plate is photographed by the monochrome photographing means through the R, G, B color filters,
A first correspondence between the pixel address of the photographing means and the pixel address of the inspection image on the color display plate is obtained from each first distributed display image obtained by the photographing, and selected from the correspondence Obtaining a second correspondence relationship between a pixel address of the photographing unit for a reference color and a pixel address of the photographing unit for another color;
With respect to other color display plates of the same standard, the second dispersed display surface is photographed by the monochrome photographing means through the color filter of the reference color in a state where the discontinuous pixels for each color are dispersedly displayed by the simple lighting method. thing,
Applying the second correspondence relationship to an image that has passed through the reference color filter obtained by the photographing to obtain a pixel address of the monochrome photographing means corresponding to a color other than the reference color;
By applying the first correspondence relationship to the pixel address of the photographing unit for the other color display plate, the first correspondence relationship between the pixel address of the color display plate and the pixel address of the monochrome photographing unit is obtained. thing,
For the other color display board, the inspection screen in which all pixels are lit by the simple lighting method is photographed by the monochrome photographing means through the R, G, B color filters, and the other color display obtained by the photographing is performed. When a defective pixel is observed from the inspection image of the plate, it corresponds to the pixel of the monochrome photographing means for displaying the defective pixel of the other color display plate from the first address correspondence relationship for the other color display plate The address of the pixel defect of the other color display panel is specified.

  In the present invention, with this simple lighting method, the inspection screen is photographed by the monochrome photographing means through the R, G, B color filters in a state where all the pixels of the color display panel are lit. The presence or absence of a defect such as a luminance defect is determined from these inspection images. In order to specify the pixel address of the defective pixel on the color display board, the following procedure is performed.

  In a state where discontinuous pixels for each color are dispersedly displayed by the simple lighting method, the first dispersed display screen of the color display plate is photographed by the monochrome photographing means through the R, G, and B color filters.

  This distributed display screen is imaged, and from each first distributed display image obtained for each filter and the inspection image, a first of the pixel address of the imaging means and the pixel address of the inspection image of the color display board is obtained. Correspondence is required.

  Accordingly, when a defect such as a luminance defect is observed from the inspection image of the first color display plate, it is difficult to detect chromatic aberration by comparing the inspection screen with each of the distributed display screens. Thus, it is possible to accurately specify the address of the defective pixel without being affected by a large aberration.

  However, for the second and subsequent color display panels of the same standard as the first sheet, the inspection screen in a state where all the pixels of the color display panel are turned on by the simple lighting method similar to the conventional one is displayed as R, G, B. Although it is necessary to shoot with a monochrome photographing means through each color filter, the second dispersed display surface is photographed with a monochrome photographing means through a color filter in a state in which discontinuous pixels for each color are dispersedly displayed by a simple lighting method. In this case, instead of the conventional three-time shooting through each color filter, a single shooting through the selected single color filter is performed.

  For example, when the G filter is selected, the second dispersion display surface is photographed by the photographing means that has passed through the G filter, thereby obtaining a single second dispersion display image. On the other hand, with respect to the first color display board, the pixel address of the photographing means for the color filter selected from the inspection image for which the first correspondence relationship has been obtained and the pixel address of the photographing means for the other color filters The second correspondence relationship is obtained. When a defect is observed from the inspection screen for the second color display board, the two sheets observed by, for example, arithmetic processing, from the second distributed display image and the first and second correspondences. The pixel address of the eye color display board can be specified.

  Therefore, for the second and subsequent color display boards, monochrome photography is performed through the second dispersion display surface through the color filter in a state in which discontinuous pixels for each color are dispersedly displayed by the simple lighting method as in the past. When photographing by means, it is not necessary to shoot three times through each color filter as in the prior art, and already obtained with respect to the second distributed display image and the first color display plate obtained by one shoot. From the first and second correspondences, it is possible to specify the address of the defective pixel of the second and subsequent color display plates.

  The address of the pixel of the color display panel that is not lit on the distributed display screen of the simple lighting method can be obtained by interpolation processing using a plurality of corresponding addresses obtained by a plurality of lighting pixels.

  As the photographing means, for example, a camera having an image sensor made of CCD or CMOS can be used. A liquid crystal display panel is used as an example of the display panel of the object to be inspected, but the method of the present invention can be applied to inspection of various electronic display devices such as plasma display devices. In general, in order to increase the resolution of an image by the image sensor, a plurality of pixel regions of the image sensor correspond to one pixel region of the liquid crystal display panel.

  The address of the image sensor pixel can be corrected according to the amount of light received by adjacent pixels of the image sensor pixel. It is desirable to obtain the pixel address of the color liquid crystal display panel based on the corrected image sensor pixel address.

  In the address correction of the image sensor pixel, an integer address can be converted to a real address, and the pixel address of the photographing unit after correction can be obtained by rounding the value of the obtained real number address. The pixel address of the color liquid crystal display panel corresponding to this pixel address can be obtained from the first correspondence relationship.

  The corrected image sensor pixel address can be converted to an integer address by rounding off the real address.

A CCD sensor is used as the image sensor, and conversion from an integer address to a real address can be performed based on the following equation.
Real number address = integer address of the pixel with the largest received light amount in each predetermined area of CCD + 0.5 × difference of received light amount of adjacent pixels ÷ (received light amount of CCD of integer address and both adjacent pixels of CCD Difference from the lower received light amount) (1)

  Further, the inspection screen and the second distributed display screen are photographed without passing through a color filter, and luminance unevenness is determined based on the address correspondence relationship from the inspection image and the distributed display image obtained from the inspection screen and the distributed display screen. The resulting LCD pixel address can be identified.

  An image quality inspection apparatus that performs the inspection method according to the present invention includes an address conversion unit. The address conversion unit includes an arithmetic processing unit that performs the arithmetic processing of the formula (1).

  According to the present invention, as described above, the discontinuous pixels are distributed by the simple lighting method for the first color display board in order to specify the address of the defective pixel in the image quality inspection of the second and subsequent color display boards. The first correspondence between the pixel address of the photographing means obtained from the first dispersed image obtained in advance by display and the pixel address of the color display panel and the second correspondence obtained from the correspondence are used. The In addition to this, for each of the second and subsequent color display boards, a second distributed display screen in which discontinuous pixels are distributedly displayed by the simple lighting method is obtained by photographing through a filter of any one color. A distributed display image is used. By using these, the address of the defective pixel is specified.

  Therefore, in the image quality inspection using the simple lighting method, the number of repetitions of the photographing process for obtaining the second dispersed display image on the second and subsequent color display plates is reduced to one third for each color display plate. Therefore, it is possible to perform an image quality inspection more quickly than in the past.

  FIG. 1 shows an image quality inspection apparatus 10 suitable for carrying out the image quality inspection method according to the present invention. FIG. 2 is a flowchart showing a procedure of the image quality inspection method for the color display board according to the present invention. Hereinafter, the present invention will be described along an example in which a color liquid crystal display panel (hereinafter, simply referred to as an LCD) is used as an object to be inspected and an image quality inspection is performed on a luminance defect.

  As shown in FIG. 1, the image quality inspection apparatus 10 is well known in the art that can move the XY plane in the X-axis and Y-axis directions and can move in the Z-axis direction perpendicular to the XY plane and about the Z-axis. The XYZθ stage 12 and a support frame 18 that is disposed on the stage and accommodates the backlight source 14 and the light diffusion plate 16 inward. On the support frame 18, an LCD 20 that is an object to be inspected is held. Thereby, the LCD 20 on the support frame 18 receives light from the backlight light source 14 through the diffusion plate 16 evenly from the back surface thereof.

  Although not shown, the LCD 20 already includes a three-color filter and a pair of polarizing plates, as is well known. A plurality of well-known shorting bars (not shown) for short-circuiting a plurality of electrodes provided for each pixel of the LCD 20 are formed at the edge of the LCD 20. These shorting bars are used for inspections such as a simple lighting inspection which will be described later, and are removed after completion of a predetermined inspection. In the image quality inspection before the polarizing plate is incorporated in the LCD 20, the LCD is disposed between a pair of parallel polarizing plates whose polarization directions are perpendicular to each other.

  Although not shown, a conventionally well-known probe assembly provided with a plurality of probes capable of contacting each shorting bar is disposed on the support frame 18. By selecting a probe to be energized among these probes, all the pixels of the LCD 20 are allowed to transmit light from the backlight light source 14 through each shorting bar, that is, all the pixels are lit and the luminance is increased. Thus, the LCD 20 can be fully displayed and the LCD 20 can be dispersedly displayed so that some of the pixels of the LCD 20 are lit by light transmission.

  In the luminance inspection of the LCD 20, the light-emitting surface of the LDC is photographed by the photographing means in a state where all the pixels of the LCD 20 are displayed, and the pixel having insufficient luminance is specified by the image processing of the image processing device 26. In order to simplify the image processing, a monochrome photographing unit such as a CCD camera 22 is used. Further, a filter device 24 capable of selecting RGB color filters is disposed between the CCD camera 22 and the LCD 20.

  The display screen of the LCD 20 is photographed by the CCD camera 22 for each filter through each color filter (R, G, B) of the filter device 24. In photographing by the CCD camera 22 through each color filter, when the light from each pixel of the LCD 20 passes through each color filter, the CCD camera for each color of the filter as shown in FIG. 3 mainly due to the difference in refractive index. 22 produces different aberrations on the screen shot at 22. Chromatic aberration gives a large error to address specification described later. In order to eliminate the influence of this chromatic aberration and to specify the exact address of the LDC, the above-described filter device 24 is used for photographing the inspection screen of the LCD 20 and the CCD camera 22 of the first distributed screen, which will be described later. Shooting is performed for each color filter.

  FIG. 4A shows an arrangement of pixels (for example, R1 to R9, G1 to G9, and B1 to B9) of the LCD 20 subjected to the image quality inspection according to the present invention. The arrangement of FIG. 1A is a stripe type pixel arrangement in which pixels of the same color are continuously arranged in the vertical direction. Further, in the illustrated example, the pixels are arranged in the horizontal direction in the order of RGB.

  The inspection screen in which all the pixels of the LCD 20 having such a stripe-type pixel array are lit is a state in which all the pixels of the LCD 20 are lit by the simple lighting method as described above on the support frame 18. The inspection screen is obtained by photographing with the CCD camera 22 through the R, G, B color filters of the filter device 24. However, even if the address is specified from the inspection screen in which all the pixels of the stripe type LCD 20 are lit, the same color continues in each stripe. Therefore, from the image of the CCD camera 22 in which such a full screen is lit. It is difficult to identify the exact pixel address of the LCD 20.

  Therefore, in order to make it possible to clearly identify the pixel address, first, for example, FIG. 4 (a) of all the pixels of the LCD 20 on the support frame 18 by the simple lighting method as described above. A part of the pixels (R2 to B2, R5 to B5, R8 to B8) shown in FIG.

  In this distributed display screen, for the red pixels R1 to R9, the pixel R2 between the pixel R1 and the pixel R3, the pixel R5 between the pixel R4 and the pixel R6, and the pixel R8 between the pixel R7 and the pixel R9 are in a non-lighting state. . Similarly, for green pixels G1 to G9, G2, G5, and G8 are in a non-lighting state, and for blue pixels B1 to B9, B2, B5, and B8 are in a non-lighting state. Therefore, in this distributed display state, pixels of the same color that are continuous in the vertical direction are not continuously lit, and pixels of the same color are lit non-continuously.

  The distributed display screen of the first LCD 20 is photographed by the CCD camera 22 through the R, G, B color filters of the filter device 24 (step S1).

5 to 7 show the CCD camera images taken by the CCD camera 22 through the R, G, B color filters of the filter device 24 in a state where all the pixels of the LCD 20 are turned on. In contrast to this all-pixel lighting screen, in the above-described distributed display screen, each pixel (R2'-B2 ', R5'-) of each CCD image corresponding to the non-lighting pixels (R2-B2, R5-B5, R8-B8). B5 ', R8' to B8 ') are not lit.

A correspondence relationship between each pixel of the LCD 20 and each pixel of the CCD camera 22 will be described in a lighting element display state in which all the pixels of the LCD 20 are turned on. FIG. 5 shows an inspection image of the CCD camera 22 obtained by photographing the inspection screen of the LCD 20 in which all the pixels in the pixel array shown in FIG. 4A are lit through the R filter of the filter device 24. By passing the R filter, light from the G pixel and B pixel other than the R pixel shown in FIG. 4A is strongly attenuated. In the illustrated example, one pixel of the LCD 20 corresponds to three pixels of the CCD camera 22. In this way, by associating a plurality of pixels of the CCD camera 22 with one pixel of the LCD 20, a captured image with high resolution can be obtained.

  In this case, among the pixels of the CCD camera 22 shown in FIG. 5, the relatively continuous light from the corresponding pixels R <b> 1 to R <b> 9 of the LCD 20 is also applied to two consecutive pixels subsequent to the pixels denoted by R <b> 1 ′ to R <b> 9 ′. However, the arithmetic processing circuit 26a of the image processing device 26 designates the highest pixel among the three consecutive pixels in the corresponding predetermined region as the incident pixel. Therefore, the inspection image shown in FIG. 5 is obtained by photographing the inspection screen of the LCD 20 shown in FIG. 4A with the CCD camera 22 through the R filter. For example, one pixel of the CCD camera 22 marked with R1 ′ in the inspection image corresponds to one pixel of the LCD 20 marked with R1 in FIG.

  Similarly, FIGS. 6 and 7 show the respective CCD images of the CCD camera 22 obtained by photographing the screen in which all the pixels of the LCD 20 are activated through the G filter and the B filter of the filter device 24. For example, one pixel of the CCD camera 22 labeled G1 ′ in the inspection image of FIG. 6 corresponds to one pixel of the LCD 20 labeled G1 in FIG. Further, one pixel of the CCD camera 22 marked with, for example, B1 ′ in the inspection image of FIG. 7 corresponds to one pixel of the LCD 20 marked with B1 in FIG.

  The inspection images in FIG. 5 to FIG. 7, that is, all-pixel lighting images, are obtained by the CCD camera 22 that retains the relative relationship with the LCD 20 on the support frame 18. By integrating with the arithmetic processing circuit 26a of the apparatus 26, an inspection image corresponding to the display screen of the LCD 20 in FIG. That is, the pixels (R1 ′ to R9 ′, G1 ′ to G9 ′, B1 ′ to B9 ′) of the CCD camera 22 on the comprehensive inspection image are the pixels (R1 to R9, G1 to G9, B1 to B1) of the LCD 20, respectively. Corresponds to B9).

  However, in order to improve the identification performance of each pixel of the same color on the image and thereby identify the exact pixel address of the LCD 20, as described in step S1, the LCD 20 is displayed in a distributed manner, and the distributed screen is displayed on the filter device 24. The image is taken by the CCD camera 22 through each color filter. On the distributed display screen (see FIG. 5) photographed through the red filter, each pixel (R2 ′, R5 ′, R8 ′) of the CCD camera 22 corresponding to the non-lighted pixel (R2, R5, R8) displays a bright spot. Never do.

  Similarly, in the distributed display screen (see FIG. 6) photographed through the green filter, each pixel (G2 ′, G5 ′, G8 ′) of the CCD camera 22 corresponding to the non-lighted pixel (G2, G5, G8) is bright. Do not display points. In the distributed display screen (see FIG. 7) photographed through the blue filter, each pixel (B2 ′, B5 ′, B8 ′) of the CCD camera 22 corresponding to the non-lighted pixels (B2, B5, B8) is a bright spot. Is not displayed.

  By integrating these distributed display images by the arithmetic processing circuit 26a of the image processing device 26, the distributed display screen of the LCD 20 of FIG. 4A (however, the pixels R2 to B2, R5 to B5, and R8 to B8 are non-displayed). A comprehensive dispersion display image as shown in FIG. 8 corresponding to (lighting) is obtained. Among the pixels of the CCD camera 22 on the total dispersion display image, pixels (R2 ′ to B2 ′, R5 ′ to B5 ′, R8) corresponding to the non-lighting pixels R2 to B2, R5 to B5, and R8 to B8 of the LCD 20. '-B8') are not displayed as volatiles.

  Due to the image processing, the same color pixels R1 'and R3', R4 'and R6', R7 'and R9', G1 'and G3', G4 'and G6 are obtained by the CCD image of the distributed display screen in which the same color is discontinuously lit. ', G7' and G9 'and B1' and B3 ', B4' and B6 ', B7' and B9 'can be clearly distinguished.

  As described above, the LCD 20 is dispersedly displayed by the simple lighting method, and the lighting pixels (R1 ′ to B1 ′, R3 ′ to B3 ′, R4'-B4 ', R6'-B6', R7'-B7 ', R9'-B9') are shown in FIG. 4 (a) as in the all-lighting integrated image shown in FIG. 4 (b). It corresponds to the pixels (R1 to B1, R3 to B3, R4 to B4, R6 to B6, R7 to B7, R9 to B9) of the LCD 20. Therefore, at least the position information of the lighting pixels (R1 'to B1', R3 'to B3', R4 'to B4', R6 'to B6', R7 'to B7', R9 'to B9') of the CCD camera 22 (Address) and the corresponding position information (address) of the pixels (R1 to B1, R3 to B3, R4 to B4, R6 to B6, R7 to B7, R9 to B9) of the LCD 20 (step S2). ), And the correspondence relationship is stored in the storage device 26b as the first correspondence relationship.

  Further, for example, the pixel position information (address) of G selected as the reference color and the position information (address) of other colors (R, G) as the reference color for the pixel information of the CCD camera 22 in the dispersed display image shown in FIG. ) Is obtained (step S2). This second correspondence relationship is also stored in the storage device 26b to be used for specifying the address for image quality inspection of the second and subsequent LCDs 20.

From the distributed display screen shown in FIG. 8, for example, based on the address (Xg, Yg) of the G pixel, the address (Xr, Yr) of the R pixel and the address (Xb, Yb) of the B pixel are shown as follows. It is.
(Xr, Yr) = (Xg-1, Yg + 1) (2)
(Xb, Yb) = (Xg + 1, Yg-1) (3)
The relational expression indicating the difference can be stored in the storage device 26b as the second correspondence relation.

  In FIG. 8, non-illuminated pixels (R2 to B2, R5 to B5, R8 to B8) are indicated by broken lines, but each pixel (R2 ', R5', The position or address of R8 ', G2', G5 ', G8', B2 ', B5', B8 ') can be obtained by a conventionally well-known interpolation method.

  As described above, in steps S1 and S2, the first correspondence relationship between the pixel address of the LCD 20 and the pixel address of the CCD camera 22 for the first LCD 20 by the distributed display and interpolation method of the LCD 20 by the simple lighting method and A second correspondence relationship for the above-described CCD pixel is obtained. Thereafter, in a state where the relative positional relationship between the CCD camera 22 and the first LCD 20 on the support frame 18 of the XYZθ stage 12 is maintained, the first LCD 20 is subjected to the simple lighting method as described above. An inspection screen in a state where all pixels of the LCD 20 are lit is photographed by the CCD camera 22 through the R, G, B color filters of the filter device 24 (step S3).

  As described above, FIGS. 5 to 7 show CCD camera images taken through the color filters. By integrating these camera images, an inspection image corresponding to the pixel display screen of the LCD 20 in FIG. 4A is obtained. When a luminance defect is observed from this inspection image, the pixels (R1 ′ to R9 ′, G1 ′ to G9 ′, B1 ′) of the CCD camera 22 indicating the luminance defect are obtained from the first correspondence relationship obtained in step S2. To B9 ′) are determined to be defects of the pixels (R1 to R9, G1 to G9, B1 to B9) of the LCD 20 (step S4).

  Next, in place of the first LCD 20 described above, a second LCD 20 having the same standard as this is installed on the support frame 18 in order to specify an address for the image quality inspection. This second LCD 20 is distributedly displayed in the same manner as described above so that the respective colors are discontinuous by the simple lighting method. The second distributed display screen for the second LCD 20 is photographed by the CCD camera 22 through any one of the reference color filters selected from R, G, and B of the filter device 24, and one second second display screen is obtained. A distributed display image is obtained (step S5).

  For example, when the G filter that is green as the reference color is selected, the distributed display image shown in FIG. 6 is obtained as the second distributed display screen. However, CCD pixels G2 ′, G5 ′, G8 ′) corresponding to some of the non-lighted pixels G2, G5, G8 of the LCD 20 are not displayed as volatile points.

  The arithmetic processing circuit 26a of the image processing device 26 applies the second correspondence relationship for the first LCD 20 stored in the storage device 26b by processing the CCD camera image of the second distributed display screen. Thus, the CCD pixel address of, for example, red and blue pixels other than the reference color is obtained from the address of the reference color pixel of the CCD camera 22 that has photographed the second distributed display screen. Further, the address of each CCD camera pixel that is not displayed as a dot corresponding to the non-lighted pixel of the LCD 20 can be obtained by the interpolation method (step S6).

  When the arithmetic processing circuit 26a obtains the CCD pixel address of, for example, red and blue pixels other than the reference color from the address of the reference color pixel of the CCD camera 22 in step S6, it next stores 1 stored in the storage device 26b. By applying the first correspondence relationship for the second LCD 20, all pixel addresses of the CCD camera 22 obtained in step S 6 and the first correspondence relationship for all pixels of the second LCD 20 are obtained. The first correspondence relationship with respect to the second LCD 20 is stored in the storage device 26b in order to be used for specifying the defect address of the inspection screen of the LCD 20 that follows.

  After the first correspondence relationship for the second LCD 20 is obtained, the simple lighting similar to that in step S3 is performed with the relative positional relationship between the LCD and the CCD camera 22 held on the support frame 18. The inspection screen in which all the pixels are turned on by the method is photographed by the CCD camera 22 through the R, G, B color filters of the filter device 24 (step S8). By this photographing, an image similar to that shown in FIGS. 5 to 7 for the second LCD 20 on the support frame 18 is obtained, and the same processing as shown in FIG. A comprehensive inspection image is obtained.

  When a luminance defect is observed from the comprehensive inspection image of the second LCD 20, the first correspondence relationship for the second LCD 20 obtained in step S7 is stored in the storage device 26b. Obtains an LCD address corresponding to the CCD image address where the luminance defect is observed from the first correspondence relationship (step S9).

  For the third and subsequent LCDs 20, the pixel addresses on the LCD 20 detected by the image quality inspection can be specified by repeating Steps S5 to S9.

  As described above, according to the inspection method according to the present invention, since the simple lighting method is adopted for the luminance inspection such as the luminance defect of the LCD 20, the individual probes are attached to all the electrodes corresponding to the respective pixels of the LCD 20. All the pixels of the LCD 20 can be lit and displayed without contact. Thereby, since the high precision is not requested | required of the arrangement | positioning precision of LCD20 on LCD20, the arrangement | positioning operation | work of LCD20 is simplified.

  In addition, in spite of adopting the simple lighting method, the address of the defective pixel of the second and subsequent LCDs 20 is obtained except that the image capturing is repeated three times for each color filter for the inspection image by full lighting for each LCD 20. In order to specify, it is not necessary to repeat the photographing three times for each color filter. That is, if a distributed display screen of the LCD 20 is photographed with respect to the filter of the selected reference color, when luminance defects are observed in all color pixels including color pixels other than the reference color on the LCD 20, for example, by calculation, the LCD 20 Can be identified quickly and accurately.

  Incidentally, as shown in FIG. 9A, in the pixel array of the LCD 20, the light from R (1) and B (1) of the CCD camera 22 corresponding to each of them as shown in FIG. 9B. Consider a case where three adjacent pixel columns are irradiated. As is apparent from the graph shown in the lower part of FIG. 10A1 among the three columns of pixels that receive light from the R (1) pixel of the LCD 20, the center pixel column has the largest amount of light received, and the amount of light received is on both sides. Attenuates evenly toward the pixel column.

  Therefore, as shown in the upper graph of FIG. 10A1, the light receiving relative intensity of the central pixel column is the highest among the three pixel columns that receive light from the R (1) pixel. Further, the light receiving relative intensities of the pixel columns on both sides thereof are low and equal to each other. Similarly, the pixel column that receives the distribution light of the graph shown in the lower part of FIG. 10 (a2) from the B (1) pixel receives the light from the B (1) pixel as shown in the upper graph. Of the three received pixel columns, the light receiving relative to the central pixel column has the highest relative intensity. Further, the light receiving relative intensities of the pixel columns on both sides thereof are low and equal to each other.

  In such a case, as shown in FIG. 9C, among the three pixel columns of the CCD camera 22, each pixel (R1 ′, B1 ′) located at the center of each central column is When it is specified to be associated with R (1) and B (1) of the LCD 20, the correspondence relationship with the pixels on the LCD 20 does not shift in the difference processing of the above formulas (2) and (3).

  However, due to mismatch between the pixel array of the LCD 20 shown in FIG. 11 (a) and the pixel array of the LCD 20 shown in FIG. 11 (b), as shown in FIG. 1) The maximum intensity position of the light distribution from the pixels may deviate from the central column of the three pixel columns, which may cause a relative intensity difference between the pixel columns on both sides of the central column. Similarly to FIG. 12 (a), as shown in FIG. 12 (b), the maximum intensity position of the light distribution from the B (1) pixel is shifted from the central column of the three pixel columns. There may be a relative intensity difference between the pixel columns on both sides of the.

  In this case, as shown in FIG. 11C, each pixel (R1 ′, B1 ′) located at the center of each center column is associated with R (1) and B (1) of the LCD 20. Specified. Therefore, an address corresponding to 5 pixels is generated between the pixels (R1 ′, B1 ′) on the pixel of the CCD camera 22, but between the two pixels (R1, B1) on the LCD 20, 4. An address difference of 3 pixels occurs.

  In such a case, the light intensities of the pixels on both sides of the central pixel row are not equal. For example, the pixels of the other colors are obtained from the pixel address of the reference color of the CCD camera 22 using the equations (2) and (3). Accurate address calculation is hindered when seeking an address.

  Therefore, the following equation is used to correct the pixel position of the central pixel row as shown in FIG.

  Real number address = integer address of the pixel with the largest received light amount in each predetermined area of CCD + 0.5 × difference of received light amount of adjacent pixels ÷ (received light amount of CCD of integer address and both adjacent pixels of CCD Difference from the lower received light amount) (1)

  By using the expression (1), a numerical value after the decimal point is introduced into the pixel address of the CCD camera 22, but the calculation result can be rounded to an integer by an arithmetic process such as rounding. Finally, an integer LCD 20 pixel address corresponding to the pixel address of the CCD camera 22 rounded to the integer is determined as the corresponding address. The calculation of Expression (1) can be performed by the calculation processing circuit 26a of the image processing device 26.

  As described above, by correcting the address of the light receiving pixel designated in the predetermined light receiving area of the CCD camera 22 with the amount of light received by both pixels, the address of the defective pixel of the LCD 20 is quickly identified with higher accuracy. It becomes possible.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, although an example in which a CCD camera is used as an image sensor has been described, an electronic image sensor such as a CMOS sensor can be used instead of the CCD sensor. In addition, the present invention can be applied to an image quality inspection of another electronic display panel such as a plasma display device as an object to be inspected.
Further, the inspection screen is photographed without passing through the color filter, the second distributed display screen through the selected reference color filter is photographed, and the inspection image obtained from the inspection screen and the second distributed display screen. Further, using the distributed display image, it is possible to specify the LCD pixel address causing the luminance unevenness based on the same first address correspondence as described above.

1 is a block diagram schematically showing a part of an apparatus for carrying out an image quality inspection method for a color display plate according to the present invention. It is a flowchart which shows the procedure of the image quality inspection method which concerns on this invention. It is explanatory drawing which shows the relationship between the light of each color pixel of LCD, and the distortion of the image of the CCD camera which receives this light, (a) is red (R), (b) is green (G), (c) is The distortion for blue (B) is shown. The correspondence between the pixel arrangement of the LCD and the corresponding pixel arrangement of the CCD camera is shown, (a) shows an example of the pixel arrangement of the LCD as the object to be inspected, and (b) shows the CCD camera of the corresponding CCD camera. An example of a pixel arrangement is shown. It is explanatory drawing which shows the image of the CCD camera which image | photographed the all lighting display screen through the red (R) filter, and its pixel address. It is explanatory drawing which shows the image of the CCD camera which image | photographed the all lighting display screen through the green (G) filter, and its pixel address. It is explanatory drawing which shows the image of the CCD camera which image | photographed the all lighting display screen through the blue (B) filter, and its pixel address. It is explanatory drawing which shows the image of the CCD camera which image | photographed the dispersion | distribution display screen, and its pixel address. It is drawing which shows the relationship (1) with the pixel of the CCD camera which receives the light from LCD, and the light-receiving amount, (a) shows an example of the light emission pixel of LCD, (b) shows each pixel (R1) of LCD. , B1) shows an example of a pixel in a light receiving area of a CCD camera that receives light from (C1), and (c) shows a pixel address (R1 ′) of a CCD pixel designated to correspond to each pixel (R1, B1) of the LCD at that time. , B1 ′). (A), (b) shows the change in the amount of light received by the CCD corresponding to each pixel (R1, B1) of the LCD, and the graphs shown at the bottom of each show the light for each pixel address on the light receiving surface of the CCD. An example of the intensity distribution is shown, and the graph shown at the top of each shows an example of the relative intensity of each CCD pixel with respect to each pixel address (R1 ′, B1 ′) of each pixel of the CCD. It is drawing which shows the relationship (2) with the pixel of the CCD camera which receives the light from LCD, and its light reception amount, (a) shows an example of the light emission pixel of LCD, (b) shows each pixel (R1) of LCD. , B1) shows an example of a pixel in a light receiving area of a CCD camera that receives light from (C1), and (c) shows a pixel address (R1 ′) of a CCD pixel designated to correspond to each pixel (R1, B1) of the LCD at that time. , B1 ′). (A), (b) shows the change in the amount of light received by the CCD corresponding to each pixel (R1, B1) of the LCD, and the graphs shown at the bottom of each show the light for each pixel address on the light receiving surface of the CCD. An example of the intensity distribution is shown, and the graph shown at the top of each shows an example of the relative intensity of each CCD pixel with respect to each pixel address (R1 ′, B1 ′) of each pixel of the CCD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image quality inspection apparatus 12 XYZ (theta) stage 14 Backlight light source 16 Light diffusing plate 18 Support frame 20 LCD
22 CCD camera 24 Filter device 26 Image processing device 26a Arithmetic processing circuit 26b Storage device

Claims (9)

Obtained by photographing the inspection screen with monochrome photographing means through R, G, B color filters in a state where all the pixels of the color display panel having the stripe type pixel arrangement are lit by the simple lighting method by the short circuit. A method for inspecting the image quality of the color display board from each inspection image,
In a state where discontinuous pixels for each color are dispersedly displayed by the simple lighting method, the first dispersion display screen of the color display plate is photographed by the monochrome photographing means through the R, G, B color filters,
A first correspondence between the pixel address of the photographing means and the pixel address of the inspection image on the color display plate is obtained from each first distributed display image obtained by the photographing, and selected from the correspondence Obtaining a second correspondence relationship between a pixel address of the photographing unit for a reference color and a pixel address of the photographing unit for another color;
With respect to other color display plates of the same standard, the second dispersed display surface is photographed by the monochrome photographing means through the color filter of the reference color in a state where the discontinuous pixels for each color are dispersedly displayed by the simple lighting method. thing,
Applying the second correspondence relationship to an image that has passed through the reference color filter obtained by the photographing to obtain a pixel address of the monochrome photographing means corresponding to a color other than the reference color;
By applying the first correspondence relationship to the pixel address of the photographing unit for the other color display plate, the first correspondence relationship between the pixel address of the color display plate and the pixel address of the monochrome photographing unit is obtained. thing,
For the other color display board, the inspection screen in which all pixels are lit by the simple lighting method is photographed by the monochrome photographing means through the R, G, B color filters, and the other color display obtained by the photographing is performed. When a defective pixel is observed from the inspection image of the plate, it corresponds to the pixel of the monochrome photographing means for displaying the defective pixel of the other color display plate from the first address correspondence relationship for the other color display plate A method for inspecting an image quality of a color display board, comprising the steps of specifying an address of a pixel defect of the other color display board.   2. The address of the pixel of the color display panel that is not lit on the distributed display screen of the simple lighting method is obtained by an interpolation process using a plurality of corresponding addresses obtained by a plurality of lighting pixels. The image quality inspection method described.   The imaging device is a camera having an image sensor made of CCD or CMOS, the display plate is a liquid crystal display plate, and a plurality of pixel regions of the image sensor correspond to one pixel region of the liquid crystal display plate. 2. The image quality inspection method according to 1.   The address of the image sensor pixel is corrected according to the amount of light received by adjacent pixels of the image sensor pixel, and the pixel address of the color liquid crystal display panel is obtained based on the corrected image sensor pixel address. The image inspection method described.   The image sensor pixel address correction is conversion from an integer address to a real address, and the rounded value of the real address is determined to determine the corrected pixel address of the photographing means, and the pixel address corresponding to the pixel address is corrected. The inspection method according to claim 4, wherein a pixel address of a color liquid crystal display panel is obtained from the first correspondence relationship.   6. The inspection method according to claim 5, wherein the corrected image sensor pixel address is obtained by rounding off a real address. 6. The inspection method according to claim 5, wherein the image sensor is a CCD sensor, and conversion from an integer address to a real number address is performed based on the following equation.
Real number address = integer address of the pixel with the largest received light amount in each predetermined area of CCD + 0.5 × difference of received light amount of adjacent pixels ÷ (received light amount of CCD of integer address and both adjacent pixels of CCD Difference from the lower received light amount) (1)   Further, the inspection screen and the second distributed display screen are photographed without passing through a color filter, and luminance unevenness is determined based on the address correspondence relationship from the inspection image and the distributed display image obtained from the inspection screen and the distributed display screen. 5. The inspection method according to claim 3 or 4, wherein the LCD pixel address that occurs is specified.   5. An image quality inspection apparatus for performing the inspection method according to claim 4, further comprising an address conversion unit, wherein the address conversion unit includes an arithmetic processing unit that performs the arithmetic processing of the equation (1).

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