JP4143660B2 - Image analysis method, image analysis apparatus, inspection apparatus, image analysis program, and computer-readable recording medium - Google Patents

Description

  The present invention relates to a method for inspecting a display panel in which a plurality of same-color picture elements are arranged in a certain direction, an apparatus therefor, an image analysis program for analyzing an image obtained by imaging the display panel, and a computer-readable record in which the image analysis program is recorded It relates to the medium.

  In recent years, the importance of automatic inspection has increased with the increase in size of liquid crystal display panels. In an automatic inspection apparatus, at least a defect that can be seen by the human eye must be detected, and thus a detection sensitivity equal to or higher than that of the human eye is required.

  However, the human eye has very high defect detection sensitivity for the following reasons 1 to 3. In other words, because 1) human eyes observe not only vertically but also obliquely with respect to the panel surface, 2) because human visual processing is analog and resolution in the luminance direction is high, 3) This is because vision has a high spatial resolution at the center of the visual field, and at the time of inspection, the portion is intensively used for inspection with high resolution.

  Therefore, in an automatic inspection apparatus using a camera, it is necessary to improve detection sensitivity as much as possible by devising an apparatus configuration and an algorithm.

  Further, conventionally, a liquid crystal display panel has a configuration in which one picture element of each color is arranged in one pixel composed of RGB. However, as the size of the panel increases, Patent Documents 1 to 3 describe. As shown, a multi-domain liquid crystal display panel that provides a plurality of divided picture elements in one picture element and expresses the brightness of the intermediate gray level of the pixel more finely by changing the brightness separately. Has come to be used.

  Regarding the detection of line defects, in the case of a conventional liquid crystal display panel, it is used that the luminance of each pixel is different from the luminance of the other pixels of the same color in the same color pixel array having a line defect. Line defects are detected. Specifically, as described in Patent Document 4, the luminance value of the picture element is added in the direction in which the same color picture elements are arranged, and the same color picture element located in the direction orthogonal to the direction of the arrangement. An algorithm has been used that detects a line having a value different from the surroundings as a line defect as compared with the value related to the arrangement of.

  However, in the multi-domain liquid crystal panel, the luminance of the divided picture elements in the line defect portion is different. As an example of a multi-domain liquid crystal panel, one picture element (for example, R1) consists of two parts (upper and lower parts), and when displaying 256 gradations in total, the upper part (from 0 to 127) R1up) changes, and the lower stage (R1low) changes until 128-256. The upper and lower parts of adjacent R picture elements are arranged in the same order in the direction of the R1up-R1low arrangement. Type (R0up-R0low-R1up-R1low-R2up-R2low). In this case, if there is a line defect, the luminance changes alternately in one line of the same color picture element by black lighting or white lighting.

Therefore, in addition to adding the luminance values of the picture elements in the direction in which the same color picture elements are lined up, a method for detecting a line defect using the fact that the luminance pattern of the divided picture elements constituting the picture element is different in the line defect portion Can be considered.
Japanese Patent Laid-Open No. 04-102830 (published April 3, 1992) JP 07-181451 (released July 21, 1995) Japanese Patent Laid-Open No. 08-184834 (released on July 16, 1996) Japanese Patent Laid-Open No. 10-240933 (published on September 11, 1998)

  However, in the above conventional line defect detection algorithm, the difference between the detection values of the defective portion and the non-defective portion is small, and even in the non-defective portion, the luminance value varies for each picture element, so that the detection sensitivity for extracting the defect is high. There arises a problem that the defect cannot be separated because it cannot be obtained.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an image analysis method and an image analysis that can detect defects in a display panel, particularly a multi-domain liquid crystal panel, with high detection sensitivity. It is to provide an apparatus and an inspection apparatus.

  In order to solve the above-described problem, the image analysis method according to the present invention images a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging unit having an imaging element, and the brightness of the obtained captured image. An image analysis method in an image analysis apparatus included in an inspection apparatus that detects a defect of the display panel by analyzing a value, wherein a luminance value of a target picture element included in the captured image and the plurality of same-color picture elements A difference absolute value calculating step of calculating a difference value with a luminance value of the same color pixel adjacent to the target pixel in the arrangement direction, and an absolute value of the difference value calculated in the difference absolute value calculating step And an average value calculating step of calculating an average value along the arrangement direction of the plurality of same-color picture elements.

  In order to solve the above-described problem, the image analysis apparatus according to the present invention images a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging unit having an imaging element, and the brightness of the obtained captured image. An image analysis apparatus in an inspection apparatus that detects a defect in the display panel by analyzing a value, and the attention value in a luminance value of a target picture element included in the captured image and the arrangement direction of the plurality of same color picture elements A difference absolute value calculating means for calculating an absolute value of a difference value between the luminance values of the same color picture elements adjacent to the picture element, and an average value of the absolute values of the difference values calculated by the difference absolute value calculating means, Average value calculating means for calculating along the arrangement direction of a plurality of same-color picture elements.

  In the conventional configuration, 1) the average value (first average value) of the luminance values of the pixels in the column of the same color pixel of interest is calculated in the image captured from the display panel, and 2) the first average value is calculated. An average value (second average value) of luminance values in the same-color picture element sequence different from the same-color picture element sequence is calculated, and a difference value between the first average value and the second average value is calculated.

  On the other hand, according to the configuration of the present invention, the difference absolute value calculating unit is configured to detect the luminance value of the pixel of interest and the arrangement direction of the same color picture element among the plurality of same color picture elements arranged in a certain direction. The absolute value of the difference value from the luminance value of the picture element adjacent to the target picture element is calculated for the same color picture element column. Then, the average value calculation means calculates the average value of the difference values calculated by the difference absolute value calculation means along the arrangement direction of the same color picture elements.

  When a line defect occurs in a column of the same color picture element, the column is in a state where a picture element having normal luminance and a picture element having abnormal luminance are mixed as compared with a normal column having no line defect.

  Therefore, if there is a line defect in a column of a certain same color pixel, the difference between the luminance value in the normal luminance pixel and the luminance value in the abnormal luminance pixel in the column as in the above configuration. By calculating, the ratio between the luminance values can be increased, and as a result, the defect detection sensitivity can be increased as compared with the case of calculating the average value of the luminance values of the entire column.

  Therefore, by applying the image analysis apparatus to the inspection apparatus, it is possible to realize an inspection apparatus that can detect defects in the display panel with high detection sensitivity.

  In a multi-domain liquid crystal display panel in which a plurality of divided picture elements are provided in one picture element, the plurality of same color picture elements means a plurality of same color divided picture elements.

Further, the image analysis method of the present invention is to display the above display by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging means having an imaging element, and analyzing the luminance value of the obtained captured image. An image analysis method in an image analysis apparatus possessed by an inspection apparatus for detecting a panel defect, wherein a maximum value of luminance values possessed by a plurality of image pickup elements that have picked up a picture element is calculated for the plurality of picked up picture elements Imaging process for arranging the absolute value of the difference between the maximum luminance value calculating step, the maximum value related to the target picture element, and the maximum value related to the same color picture element adjacent to the target picture element in the arrangement direction of the same color picture elements Difference absolute value calculating step for each element column, and an average for calculating the absolute value of the difference value calculated in the difference absolute value calculating step along the arrangement direction of the plurality of same-color picture elements Value calculator It is characterized in that it comprises and.

According to the above configuration, one picture element is imaged by the plurality of image sensors. In other words, one picture element is divided into a plurality of pixels in the captured image. Then, the maximum brightness value calculation step, out of the luminance values in which a plurality of image pickup elements of the captured certain picture elements (pixels) have to calculate the maximum one. Then, the difference absolute value calculation step, for each column of image pickup elements, is calculated and the maximum values for target pixels, the absolute value of the difference value between the maximum value relating to the same color pixels adjacent to the target picture element.

  As described above, by obtaining the maximum value of the luminance values of the plurality of image sensors that have captured the target pixel, the ratio of the luminance value of the normal luminance pixel to the luminance value of the abnormal luminance pixel is further increased. Therefore, the defect detection sensitivity can be increased as compared with the case where the luminance value of the entire noticeable pixel is calculated.

  In order to solve the above-described problem, the image analysis method according to the present invention images a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging unit having an imaging element, and the brightness of the obtained captured image. An image analysis method in an image analysis apparatus included in an inspection apparatus that detects a defect of the display panel by analyzing a value, wherein a luminance value of a target picture element included in the captured image and the plurality of same-color picture elements A difference value calculation step of calculating a difference value between the luminance values of the same color picture elements adjacent to the target pixel in the arrangement direction, and a standard deviation of the difference values calculated in the difference value calculation step are represented by the plurality of same colors. And a standard deviation calculating step of calculating for each column of image pickup devices arranged in the arrangement direction of the picture elements.

  In order to solve the above-described problem, the image analysis apparatus according to the present invention images a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging unit having an imaging element, and the brightness of the obtained captured image. An image analysis apparatus included in an inspection apparatus that detects a defect of the display panel by analyzing a value, wherein the luminance value of a pixel of interest included in the captured image and the arrangement direction of the plurality of same-color picture elements A difference value calculating means for calculating a difference value between luminance values of the same color picture elements adjacent to the target picture element, and a standard deviation of the difference values calculated by the difference value calculating means, an array of the plurality of same color picture elements And a standard deviation calculating means for calculating for each column of the image pickup elements arranged in the direction.

  According to the above configuration, the difference value calculating unit calculates a difference value between the luminance value of the target pixel and the luminance value of the same color pixel adjacent to the target pixel, and the standard deviation calculating unit calculates the difference. The standard deviation of the values is calculated for each column of image sensors arranged in the arrangement direction of the same color picture elements.

  As described above, by obtaining the standard deviation of the difference value, it is possible to increase the ratio between the luminance value of the normal luminance pixel and the luminance value of the defective pixel having a luminance value outside the normal luminance value range. it can. Therefore, it is possible to detect a defective pixel having a luminance value outside the normal luminance value range with higher sensitivity than the conventional configuration.

  Therefore, by applying the image analysis apparatus to the inspection apparatus, it is possible to realize an inspection apparatus that can detect defects in the display panel with high detection sensitivity.

  In order to solve the above-described problem, the image analysis method according to the present invention images a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging unit having an imaging element, and the brightness of the obtained captured image. An image analysis method in an image analysis apparatus included in an inspection apparatus that detects a defect of the display panel by analyzing a value, the interval between the plurality of same-color picture elements in the captured image, When the interval between the part and the part corresponding to the target part of the same color picture element adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements is defined as the picture element interval, from the captured image, An extraction process for forming a group of luminance values by extracting the luminance values of the image sensor at intervals of the pixel elements along the arrangement direction of a plurality of same-color picture elements, and the luminance formed in the extraction process Group of values A standard deviation calculating step for calculating the standard deviation of the luminance value for each group of the luminance values, and calculating a maximum value of the standard deviation calculated in the standard deviation calculating step for each of the plurality of columns of the same color pixels. And a maximum value calculating step.

  In order to solve the above-described problem, the image analysis apparatus according to the present invention images a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging unit having an imaging element, and the brightness of the obtained captured image. An image analysis apparatus included in an inspection apparatus that detects a defect of the display panel by analyzing a value, the interval between the plurality of same-color picture elements in the captured image, the attention part of the attention picture element, and the In the arrangement direction of a plurality of same-color picture elements, when the interval between the same-color picture elements adjacent to the target picture element and the part corresponding to the target part is set as the picture element interval, the plurality of same-color pictures from the captured image Extracting the brightness value of the image sensor for each picture element interval along the element arrangement direction to form a brightness value group, and the brightness value group formed by the extraction means Included brightness value standard Standard deviation calculating means for calculating the difference for each group of luminance values, and maximum value calculating means for calculating the maximum value of the standard deviation calculated by the standard deviation calculating means for each row of the same color picture elements. It is characterized by providing.

  According to the above configuration, the extraction unit extracts the luminance value of the imaging element (pixel) from the captured image of the display panel at every pixel interval along the arrangement direction of the same color picture elements. Form a group. That is, the group of luminance values is a set of luminance values of an image pickup element that picks up a specific portion of a picture element, and is a set relating to a column of the same color picture element to be noticed.

  The standard deviation calculating means calculates the standard deviation of the luminance values included in the extracted luminance value group for each luminance value group, and the maximum value calculating means calculates the maximum value of the calculated standard deviation of the same color pixel. Calculate for each column.

  As described above, by obtaining the maximum value of the standard deviation of the luminance values included in the group of luminance values, the defective picture having the luminance value in the normal luminance value picture element and the luminance value outside the normal luminance value range. The ratio with the original luminance value can be increased. Therefore, it is possible to detect a defective pixel having a luminance value outside the normal luminance value range with higher sensitivity than the conventional configuration.

  Therefore, by applying the image analysis apparatus to the inspection apparatus, it is possible to realize an inspection apparatus that can detect defects in the display panel with high detection sensitivity.

  An inspection apparatus for detecting a defect in the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction by an imaging means having an imaging element and analyzing a luminance value of the obtained captured image An inspection apparatus comprising the image analysis apparatus and a defect detection unit that determines the presence or absence of a defect by comparing a luminance value of a pixel calculated by the image analysis apparatus with a predetermined threshold value. Is included in the technical scope.

  The image analysis apparatus may be realized by a computer. In this case, a control program (image) for causing the image analysis apparatus to be realized by the computer by causing the computer to operate as the respective means. Analysis program) and a computer-readable recording medium on which the analysis program is recorded are also included in the technical scope of the present invention.

  In the image analysis method according to the present invention, as described above, the absolute value of the difference value between the luminance value of the pixel of interest included in the captured image and the luminance value of the same color pixel adjacent to the pixel is calculated as described above. The difference absolute value calculation step for calculating a row of identical color elements, and the average for calculating the absolute value of the difference values calculated in the difference absolute value calculation step along the arrangement direction of a plurality of the same color pixels And a value calculation step.

As described above, the image analysis apparatus according to the present invention has the luminance value of the pixel of interest included in the captured image and the luminance of the pixel of the same color adjacent to the pixel of interest in the arrangement direction of the plurality of pixels of the same color. A difference absolute value calculating means for calculating an absolute value of a difference value from the value, and an average value of the absolute values of the difference values calculated by the difference absolute value calculating means along an arrangement direction of a plurality of same-color picture elements It is the structure provided with the average value calculation means to calculate.
In the image analysis method according to the present invention, as described above, a display panel in which a plurality of same-color picture elements are arranged in a certain direction is imaged by an imaging means having an imaging element, and the luminance value of the obtained captured image is analyzed. An image analysis method in an image analysis apparatus possessed by an inspection apparatus for detecting a defect of the display panel, wherein the maximum luminance value of a plurality of image sensors that have imaged a picture element The maximum luminance value calculation step for calculating the element, the absolute value of the difference value between the maximum value related to the target picture element and the maximum value related to the same color picture element adjacent to the target picture element, and the arrangement direction of the same color picture element The difference absolute value calculation step calculated for each column of the image pickup devices arranged in a row, and the average value of the absolute values of the difference values calculated in the difference absolute value calculation step along the arrangement direction of the plurality of same-color picture elements Calculate A configuration including a average value calculating step.

  As described above, the image analysis method according to the present invention includes the luminance value of the pixel of interest included in the captured image and the luminance of the pixel of the same color adjacent to the pixel of interest in the arrangement direction of the plurality of pixels of the same color. A difference value calculating step for calculating a difference value with respect to the value, and a standard deviation of the difference value calculated in the difference value calculating step is calculated for each column of the imaging elements arranged in the arrangement direction of the plurality of same-color picture elements. And a standard deviation calculating step.

  As described above, the image analysis apparatus according to the present invention has the luminance value of the pixel of interest included in the captured image and the luminance of the pixel of the same color adjacent to the pixel of interest in the arrangement direction of the plurality of pixels of the same color. A difference value calculating means for calculating a difference value from the value, and a standard deviation of the difference value calculated by the difference value calculating means is calculated for each column of the imaging elements arranged in the arrangement direction of the plurality of same-color picture elements. And a standard deviation calculating means.

  As described above, the image analysis method according to the present invention is the interval between the plurality of same-color picture elements in the captured image, and the target part of the target picture element and the attention direction in the arrangement direction of the plurality of same-color picture elements. When the interval between the pixel of the same color adjacent to the pixel and the portion corresponding to the target portion is defined as the pixel interval, the pixel is extracted from the captured image along the arrangement direction of the plurality of pixels of the same color. The luminance value of the image sensor is extracted at each interval to form a luminance value group, and the standard deviation of the luminance value included in the luminance value group formed in the extraction step is the luminance value. A standard deviation calculating step for each group, and a maximum value calculating step for calculating the maximum value of the standard deviation calculated in the standard deviation calculating step for each row of the plurality of same-color picture elements.

  As described above, the image analysis apparatus according to the present invention is the interval between the plurality of same-color picture elements in the captured image, and the target part of the target picture element and the attention direction in the arrangement direction of the plurality of same-color picture elements. When the interval between the pixel of the same color adjacent to the pixel and the portion corresponding to the target portion is defined as the pixel interval, the pixel is extracted from the captured image along the arrangement direction of the plurality of pixels of the same color. The brightness value of the image sensor is extracted at each interval to extract a brightness value group, and the brightness value standard deviation included in the brightness value group formed by the extraction means is defined as the brightness value. A standard deviation calculating means for calculating each group, and a maximum value calculating means for calculating the maximum value of the standard deviation calculated by the standard deviation calculating means for each row of the plurality of same-color picture elements.

  Therefore, it is possible to detect the defect of the display panel with higher detection sensitivity than the defect detection apparatus to which the conventional defect detection method is applied.

  An embodiment of the present invention will be described below with reference to FIGS.

(Configuration of the liquid crystal display panel inspection apparatus 1)
The liquid crystal display panel inspection apparatus 1 (hereinafter referred to as the inspection apparatus 1) captures an image of a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging unit having an imaging element, and the brightness of the obtained captured image The display panel defect is detected by analyzing the value, and the display panel defect is detected by first to fourth inspection methods described later.

  In the following, the display panel defect specifically means a picture element having a luminance value out of a predetermined range among a plurality of picture elements constituting the display panel.

  FIG. 2 is a schematic diagram showing the configuration of the liquid crystal display panel inspection apparatus 1 of the present embodiment. As shown in FIG. 2, the inspection apparatus 1 includes a camera 2 (imaging means) and a control device 3 as main components.

  The camera 2 is for imaging the liquid crystal display panel 20, and has a plurality of imaging elements arranged in a matrix. Examples of the camera 2 include a CCD camera and a c-MOS camera. The camera 2 is attached to the frame 13 of the inspection apparatus 1 with a jig 14.

  The control device 3 includes an image conversion unit 4 (image analysis device) having an image reading function, and controls the operation of the inspection device 1.

  A multi-domain liquid crystal display panel 20 to be inspected by the inspection apparatus 1 is placed on the carriage 15 and arranged in the inspection apparatus 1. The liquid crystal display panel 20 is imaged by the camera 2, and the captured image is sent to the control device 3 and processed by a predetermined algorithm.

  In addition, although the inspection apparatus 1 is provided with the illumination 11 and the lighting circuit 12 so that it may mention later, these members are abbreviate | omitted in FIG.

(Configuration of control device 3)
FIG. 1 is a functional block diagram showing the configuration of the control device 3. As shown in FIG. 1, the control device 3 includes an image conversion unit 4, a main control unit 5, a storage unit 6, a defect detection unit 7 (defect detection means), a display unit 8, and an input unit 9.

  The image conversion unit 4 performs processing to be described later on the captured image of the liquid crystal display panel 20 captured by the camera 2, and calculates a luminance value for defect detection. The configuration of the image conversion unit 4 will be described later.

  The main control unit 5 controls the camera 2, the illumination 11, and the lighting circuit 12 in addition to each unit of the control device 3. The lighting circuit 12 is connected to the liquid crystal display panel 20 and controls the lighting of the liquid crystal display panel 20.

  The storage unit 6 stores various setting values used in the inspection apparatus 1, and information is written and read by the main control unit 5.

  The defect detection unit 7 determines the defect of the liquid crystal display panel 20 by comparing the luminance value calculated by the image conversion unit 4 with a predetermined reference value.

  The display unit 8 displays inspection conditions, inspection results, and the like, and the input unit 9 receives an operation of the inspection apparatus 1 by an operator. Which of the first to fourth inspection methods is used for inspection is designated by the operator via the input unit 9.

(Configuration of the image conversion unit 4)
As shown in FIG. 1, the image conversion unit 4 includes a difference absolute value calculation unit 41 (difference absolute value calculation unit), an average value calculation unit 42 (average value calculation unit), a maximum value filter calculation unit 43, and a difference value calculation unit. 44 (difference value calculation means), standard deviation calculation section 45 (standard deviation calculation means), system division calculation section 46 (extraction means), and maximum value calculation section 47 (maximum value calculation means).

  The difference absolute value calculation unit 41 calculates the luminance value of the noticed divided picture element (for example, the R picture element 22a in FIG. 6) and the same color divided picture element adjacent to the picture element (for example, the R picture element in FIG. 6). The absolute value of the difference value from the luminance value of 22b) is calculated for the arrangement of the same color picture elements (rows of R picture elements, G picture elements or B picture elements).

  The average value calculation unit 42 calculates the average value of the absolute values of the difference values calculated by the difference absolute value calculation unit 41 along the arrangement direction of the same color picture elements.

  The maximum value filter calculation unit 43 calculates the maximum value of the luminance values of a plurality of image sensors that have captured the target divided picture element for each column of the image sensors arranged in the arrangement direction of the same color divided picture elements.

  The difference value calculation unit 44 calculates a difference value between the luminance value of the divided picture element of interest and the luminance value of the same color divided picture element adjacent to the divided picture element.

  The standard deviation calculation unit 45 calculates the standard deviation of the difference values calculated by the difference value calculation unit 44 for each column of image pickup elements arranged in the arrangement direction of the same color picture elements.

  The system division calculation unit 46 extracts, from the captured image of the liquid crystal display panel 20, the luminance value of the imaging element (the luminance value of the pixel of the captured image) for each pixel interval described later along the arrangement direction of the same color picture elements. Thus, a group (system) of luminance values is formed.

  The maximum value calculation unit 47 calculates the standard deviation of the luminance values included in the system formed by the system division calculation unit 46 for each system of luminance values.

  Details of each unit included in the image conversion unit 4 will be described later.

(Configuration of LCD panel)
The liquid crystal display panel 20 to be inspected by the inspection apparatus 1 is a display panel in which a plurality of same-color picture elements are arranged in a certain direction. More specifically, a plurality of divided picture elements are provided in one picture element. This is a multi-domain liquid crystal display panel that changes the brightness separately.

  The inspection object of the inspection apparatus 1 is not limited to a multi-domain liquid crystal display panel as long as it is a display panel in which a plurality of same-color picture elements are arranged in a certain direction. The inspection apparatus 1 is particularly effective for a display panel in which the luminance of the picture elements constituting the line defect changes alternately.

  FIG. 3 is a schematic diagram showing the arrangement of divided picture elements in a multi-domain liquid crystal display panel 20 (display panel). As shown in the figure, in the liquid crystal display panel 20, one pixel 21 is composed of RGB three-color picture elements (R picture element 22, G picture element 23, and B picture element 24). It is divided into smaller divided picture elements. Specifically, the R picture element 22 is divided into the divided R picture element 22a and the divided R picture element 22b, the G picture element 23 is divided into the divided G picture element 23a and the divided G picture element 23b, and the B picture element 24 is divided into the divided B elements. It is divided into a picture element 24a and a divided B picture element 24b.

  The divided picture elements of the same color are arranged in a certain direction (X-axis direction in FIG. 3), and form an array of the same color picture elements (rows of R picture elements, G picture elements, and B picture elements).

  In FIG. 3, alphabets are written on each divided picture element, which indicate divided picture elements in which R is red, G is green, and B is blue. In the following description, a case where one picture element is composed of two divided picture elements will be described, but the same algorithm can be used even when there are three or more divided picture elements.

(Correspondence relationship between image sensor 25 and pixel 21)
FIG. 4 is a diagram showing the allocation of the image pickup device of the camera 2 to the pixels 21 of the liquid crystal display panel 20. As shown in the figure, the image sensor 25 of the camera 2 images the liquid crystal display panel 20 at a magnification at which a predetermined number of image sensors 25 are assigned to the pixels 21 of the liquid crystal display panel 20. In the case shown in FIG. 4, the image sensor 25 is assigned in a 6 × 6 manner vertically and horizontally per pixel 21. When one picture element is divided into N divided pixels, it is necessary to allocate at least N × N image sensors, and it is preferable that more image sensors be allocated.

(Problems of conventional inspection methods)
Here, problems of the conventional inspection method will be described.

  The relationship between the luminance setting value and the actual luminance value in the liquid crystal display panel 20 can be represented by a graph as shown in FIG. FIG. 5 is a graph showing the relationship between the set luminance value of the liquid crystal display panel 20 and the actual luminance value. As shown in the figure, the brightness value in the intermediate gradation has a steep slope with respect to the brightness setting value. For this reason, the actual luminance value changes greatly with changes in the luminance setting, and it is possible to obtain a relatively high detection accuracy even with a conventional inspection algorithm when inspecting a liquid crystal display panel that is lit at intermediate luminance. is there.

  On the other hand, in the black lighting inspection and the white lighting inspection, the gradient of the luminance value with respect to the luminance setting value is small and the change in the luminance value is small, so it is difficult to detect a minute change in the luminance setting. Insufficient defect detection accuracy may not be obtained.

  Therefore, the panel inspection method in the present invention can be used alone, but can also be used in combination with a conventional method according to the luminance setting of the liquid crystal display panel to be inspected.

(Conventional inspection method for black lighting inspection)
Next, a conventional inspection method in the black lighting inspection will be described.

  FIG. 6 shows line defects when the liquid crystal display panel 20 shown in FIG. 3 is lit black. FIG. 6 is a diagram showing the luminance of each divided picture element when the liquid crystal display panel is lit black. In the figure, each divided picture element has a luminance of a value written together with the alphabet written on each divided picture element. As shown in the figure, the divided R picture elements 22a and 22b have the same luminance (brightness value 0) when black is lit, but in the liquid crystal display panel 20 in the case where there is a line defect, the line defect portion 26 has a bright spot defect. Since only the divided R picture element 22c that is a picture element lights up, the luminance values of the divided R picture element 22c and the divided R picture element 22d that is the same color picture element adjacent to the divided R picture element 22c are different. If the luminance of the divided R picture element 22c is R1, and the luminance of the divided R picture element 22d is R0, the pattern of the divided picture element is repeated in the X-axis direction in FIG.

  FIG. 7 shows an image obtained by imaging the liquid crystal display panel 20 shown in FIG. 6 with the assignment of the image sensor 25 shown in FIG. FIG. 7 is a diagram illustrating the luminance value of each image sensor 25 when the liquid crystal display panel 20 is imaged. In the figure, the luminance of each image sensor 25 is shown stepwise (0 to 3) by the value marked on each image sensor 25. The luminance value of the imaging element 25 is a value based on the luminance of the liquid crystal display panel 20 and can be said to be a luminance value of a pixel forming a captured image obtained by imaging the liquid crystal display panel 20. BR indicates an image sensor that captures an area including the divided B picture element and the divided R picture element. RR indicates an image sensor that captures an area that does not include a picture element other than the divided R picture element.

  In FIG. 7, an image pickup element 25 indicated by white is an image of a divided R picture element having a bright spot defect.

  When the ratio of the vertical length of each divided picture element, the horizontal length, and the width of the black matrix portion separating the divided picture elements is 7: 4: 2, the luminance value of each image sensor is expressed by the following equation. Is done.

BR0 = B0 / 9 + R0 / 9
BR1 = B0 / 6 + R0 / 6
RR0 = R0 / 3
RR1 = R0
RG0 = R0 / 9 + G0 / 9
RG1 = R0 / 6 + G0 / 6
GG0 = G0 / 3
GG1 = G0
GB0 = G0 / 9 + B0 / 9
GB1 = G0 / 6 + B0 / 6
BB0 = B0 / 3
BB1 = B0
BR2 = B0 / 9 + R1 / 9
BR3 = B0 / 6 + R1 / 6
RR2 = R1 / 3
RR3 = R1
RG2 = R1 / 9 + R0 / 9
RG3 = R1 / 6 + R0 / 6
In the conventional inspection method, the inspection is performed in the following three stages.
1) The average value (first average value) of the luminance values of the image sensor in the direction in which the same color picture elements are arranged (X-axis direction) in the captured image is calculated.
2) An average value (second average value) of corresponding luminance values of the same color pixels in adjacent pixels in a direction (Y-axis direction) orthogonal to the arrangement direction is calculated, and the first average value and the second average value are calculated. The difference from the average value is calculated.
3) A line defect is extracted by comparing the calculated difference value with a predetermined threshold value.

  In the above processing, the average value of the luminance values is calculated. However, the luminance values of the imaging elements in the direction in which the same color picture elements are arranged (X-axis direction) may be added. These are equivalent as processing.

  FIG. 8 shows the results when the above processing is performed on the image sensor shown in FIG. FIG. 8 is a diagram showing the result of the line defect detection processing by the conventional inspection method. In the same figure, the line pointed by the arrow 27a indicates the result of calculating the average of the luminance values in the arrangement direction (X-axis direction) of the same color picture elements. The row indicated by the arrow 27b is a row of the same-color picture elements located at positions separated by six image sensors in the Y-axis direction from the above-described average value and the same-color picture element row for which the average value was calculated. This is a calculation of the difference from the average value of the luminance values of the same color picture elements in the pixel to be processed. When the difference value is negative, 0 is written. The value of the line indicated by the arrow 27c in the row of the arrow 27b is the detected value of the line defect. That is, the average value of the luminance values in the line of same color picture elements having line defects is 5 (R0 + R1) / 18, and the difference value is 5 (R1−R0) / 18.

(First inspection method of the inspection apparatus 1)
On the other hand, in the inspection apparatus 1, the first inspection is performed by the following three-stage processing.
1) In a captured image of the liquid crystal display panel 20, in a direction (X-axis direction) where the image sensor that captured the target divided picture element has the same color and the same color picture elements are arranged, the adjacent divided picture element is imaged. The absolute value of the difference from the brightness of the image sensor thus obtained is calculated (difference absolute value calculating step).
2) Next, an average value (absolute difference average value) in the direction in which the divided picture elements are arranged (X-axis direction), which is an average value of the absolute values of the differences, is calculated (average value calculation step).
3) The difference absolute average value is compared with a predetermined threshold value, and it is determined that there is a defect when the difference absolute average value exceeds the threshold value.

  The values calculated by the above processing are shown in FIG. FIG. 9 is a diagram illustrating a defect detection result by the first inspection method in the inspection apparatus 1. Note that FIG. 6 shows only the arrangement of the image sensor shown in FIG.

  The column indicated by the arrow 28a indicates the luminance value of the imaging element that captured the segmented pixel of interest and the segmented picture element of the same color adjacent to the segmented pixel located at a position separated from the imaging element by three imaging elements. The absolute value of the difference from the luminance value of the corresponding image sensor is shown. The row indicated by the arrow 28b indicates a value (absolute difference average value) obtained by averaging the absolute values of the differences in the direction in which the same color picture elements are arranged. The value indicated by the arrow 28c in the row of the arrow 28b, that is, 5 | R1-R0 | / 9 is the detected value of the line defect. In other words, it is preferable to calculate the detection value of the line defect from the luminance value of the image sensor that has the largest area in which the divided picture element is imaged among the plurality of image sensors that have imaged the divided picture element of interest.

  When the detection value (5 (R1-R0) / 18) in FIG. 8 and the detection value (5 | R1-R0 | / 9) in FIG. 9 are compared, the detection value by the inspection apparatus 1 at the location where there is a line defect is It has a value twice that of the conventional method, and it can be seen that the detection sensitivity is improved.

  In the case of white lighting and intermediate gradation, only the actual values of the luminances R0, G0, B0, and R1 of the divided picture elements in the liquid crystal display panel 20 change. Same as the case. Therefore, in the case of white lighting and intermediate gradation, the defect detection sensitivity can be improved by the inspection method in the inspection apparatus 1 as in the case of black lighting.

  As described above, in the first inspection method, the luminance value of the imaging element that captured a part of the divided picture element of interest and the part corresponding to the part of the same-color divided picture element adjacent to the divided picture element are imaged. A difference absolute value calculating step of calculating an absolute value of a difference value with respect to the luminance value of the image pickup device for the plurality of same-color divided picture elements, and an absolute value of the difference value calculated in the difference absolute value calculating step And an average value calculating step for calculating the average value along the arrangement direction of the plurality of same-color divided picture elements.

(Processing flow for performing the first inspection)
Next, a flow of processing for performing the above-described first inspection in the inspection apparatus 1, particularly the image conversion unit 4, will be described with reference to FIG. FIG. 10 is a flowchart showing a flow of processing for performing the first inspection in the inspection apparatus 1.

  A captured image of the liquid crystal display panel 20 captured by the camera 2 is input to the difference absolute value calculation unit 41 of the image conversion unit 4 via the main control unit 5.

  Upon receiving this captured image, the difference absolute value calculation unit 41 calculates the absolute value of the above-described difference from the luminance value of each pixel of the captured image (the luminance value of each image sensor) (S1), and calculates the calculated difference. Is output to the average value calculator 42.

  When the absolute value of the difference is received, the average value calculating unit 42 calculates the above-described absolute difference average value from the absolute value of the difference (S2). Then, the average value calculation unit 42 outputs the calculated absolute difference average value to the defect detection unit 7 via the main control unit 5.

  When the difference absolute average value is received, the defect detection unit 7 compares the difference absolute average value with a predetermined threshold value, and determines that a line defect exists if the difference absolute average value is equal to or greater than the predetermined threshold value ( If it is not, it is determined that the product is non-defective (NO in S3).

(Second inspection method of the inspection apparatus 1)
Next, a second inspection method in the inspection apparatus 1 will be described with reference to FIGS. In the second inspection method, before the inspection by the first inspection method, the luminance value of the image pickup device that picks up the divided picture element of interest in the captured image shown in FIG. A filter function for obtaining the maximum value is applied.

Specifically, the second inspection method includes the following four stages of processing.
1) When the divided pixel adjacent to the divided pixel of interest is in the position separated from the divided picture element by N with respect to the direction in which the same color picture elements are arranged (X-axis direction), That is, when one divided picture element is imaged by N imaging elements in the X-axis direction, the maximum value for obtaining the maximum value of the luminance values of the N imaging elements in the X-axis direction of the divided picture element of interest. A value filter function is applied to the luminance value of each image sensor (maximum luminance value calculating step).
2) With respect to a captured image having a luminance value subjected to the maximum value filter function, the luminance of the image pickup element that picks up the divided picture element of interest and the divided picture element in the direction in which the same color picture elements are arranged (X-axis direction) The absolute value of the difference from the luminance of the image sensor that has captured the adjacent divided picture elements is calculated (difference absolute value calculating step).
3) An average value (absolute difference average value) in the direction of the arrangement of the divided picture elements (X-axis direction), which is an average value of the absolute values of the differences, is calculated.
4) The difference absolute average value is compared with a predetermined threshold value, and it is determined that there is a defect when the difference absolute average value exceeds the threshold value.

  The values calculated by the above processing are shown in FIG. FIG. 11 is a diagram illustrating a defect detection result obtained by the second inspection method in the inspection apparatus 1. In the figure, only the arrangement of the image sensor shown in FIG.

  In FIG. 11, the column indicated by the arrow 29a is the value of each image sensor generated after the above-described processing for obtaining the maximum value, and the column of the arrow 29b is separated by 3 image sensors with respect to the maximum value. Further, the absolute value of the difference from the luminance value at the position of the adjacent same-color divided picture element is calculated. Further, the line indicated by the arrow 29c is obtained by calculating the average of the absolute values of the differences along the arrangement of the same color picture elements. A specific calculation example will be described below.

  In the captured image shown in FIG. 7, one divided picture element is captured by three image sensors in the X-axis direction. For example, in the case of a divided R picture element having a bright spot defect, the center portion thereof is imaged by a row of imaging elements composed of RR2, RR3, and RR2. In this case, the maximum value of the luminance values of the three image sensors in the X-axis direction of the divided picture element is the luminance value (R1) that RR3 has. Therefore, the luminance values of RR2, RR3, and RR2 are all converted to R1.

  In the case of RR3, the absolute value of the difference between the luminance value (R1) of RR3 and the luminance value (R0) of RR1, which is an image sensor located at a position away from the RR3 by three image sensors in the X-axis direction ( | R1-R0 |) is calculated.

  Further, an average value (| R1−R0 |) of the absolute values of the differences in the column of the imaging elements arranged in the X-axis direction is calculated. This average value is used as a detection value of the line defect portion.

  In FIG. 11, the detected value (| R1-R0 |) of the line defect indicated by the arrow 29c is further larger than the detected value (5 | R1-R0 | / 9) shown in FIG. .

  As described above, the second inspection method is as follows: 1) For each column of image sensors that arranges the maximum value of the luminance values of a plurality of image sensors that image the target divided picture element in the arrangement direction of the divided picture elements. The absolute value of the difference value between the maximum luminance value calculation step to be calculated, 2) the maximum value related to the divided picture element of interest, and the maximum value related to the same color divided picture element adjacent to the divided picture element is And a difference absolute value calculating step for calculating for each column.

(Processing flow for performing the second inspection)
Next, a flow of processing for performing the above-described second inspection in the inspection apparatus 1, particularly the image conversion unit 4, will be described with reference to FIG. FIG. 12 is a flowchart showing a flow of processing for performing the second inspection in the inspection apparatus 1.

  A captured image of the liquid crystal display panel 20 captured by the camera 2 is input to the maximum value filter calculation unit 43 of the image conversion unit 4 via the main control unit 5.

  Upon receiving this captured image, the maximum value filter calculation unit 43 performs the maximum value filter function on the luminance value of each pixel forming the captured image (the luminance value of each image sensor) and calculates (S11). The luminance value is output to the difference absolute value calculation unit 41.

  Since the subsequent processing flow is the same as the processing flow for performing the first inspection described above, a description thereof will be omitted.

(Third inspection method of the inspection apparatus 1)
Next, a third inspection method in the inspection apparatus 1 will be described with reference to FIGS. In the third inspection method, the difference value between the luminance values of the imaging elements corresponding to the divided picture elements adjacent to each other in the direction in which the same color picture elements are arranged in the captured image of the liquid crystal display panel 20 is calculated. The standard deviation of the difference value is calculated and compared with a predetermined threshold value.

Specifically, the third inspection method includes the following processes.
1) In the captured image, a difference value between the luminances of the imaging elements corresponding to the divided picture elements adjacent in the direction in which the same color picture elements are arranged (X-axis direction) is calculated (difference value calculation step).
2) Next, an average value of the difference values of the image sensors arranged in the X-axis direction is calculated, and a standard deviation of the difference value is calculated (standard deviation calculation step).
3) The value of the standard deviation is compared with a predetermined threshold value, and if the standard deviation value exceeds the threshold value, it is determined that there is a defect.

  According to the third inspection method, the result of the above calculation based on the luminance value of the captured image shown in FIG. 7 is as shown in FIG. FIG. 13 is a diagram illustrating a defect detection result obtained by the third inspection method in the inspection apparatus 1.

  In the figure, only those corresponding to the image pickup device that picks up an image of the defective portion shown in FIG. 7 and its periphery are shown. In FIG. 13, the column indicated by the arrow 30a indicates the difference from the adjacent divided picture elements separated by three image sensors, and the row indicated by the arrow 30b calculates the standard deviation in the direction of the arrangement of the same color picture elements. The results are shown. A specific calculation example will be described below.

  In the captured image shown in FIG. 7, one divided picture element is captured by three image sensors in the X-axis direction. For example, in the case of a divided R picture element having a bright spot defect, the center portion thereof is imaged by a row of imaging elements composed of RR2, RR3, and RR2.

  In the case of RR3, a difference value (R0-R1) between the luminance value (R1) of RR3 and the luminance value (R0) of RR1 that is an image sensor located at a position away from the RR3 by three image sensors in the X-axis direction. Is calculated.

  Then, the standard deviation of the difference values in the image sensor columns arranged in the X-axis direction including the image sensor columns (columns formed by repetition of RR2, RR3, RR2, RR0, RR1, and RR0) is calculated. The value of this standard deviation is used as a detection value for the line defect portion.

  As shown in FIG. 13, the detected value (the value obtained by multiplying the square root of 33 by (R1-R0) divided by 9) by the third inspection method indicated by the arrow 30c is shown in FIG. It is larger than the detected value (5 (R1-R0) / 18) shown, and it can be seen that the detection sensitivity is improved.

  As described above, the third inspection method includes a difference value calculation step for calculating a difference value between the luminance value of the divided pixel element of interest and the luminance value of the same-color divided pixel element adjacent to the divided pixel element, A standard deviation calculating step of calculating the standard deviation of the difference values calculated in the value calculating step for each column of the image pickup elements arranged in the arrangement direction of the same color picture elements.

(Processing flow for performing the third inspection)
Next, a flow of processing for performing the above-described third inspection in the inspection apparatus 1, particularly the image conversion unit 4, will be described with reference to FIG. FIG. 14 is a flowchart showing a flow of processing for performing the third inspection in the inspection apparatus 1.

  A captured image of the liquid crystal display panel 20 captured by the camera 2 is input to the difference value calculation unit 44 of the image conversion unit 4 via the main control unit 5.

  Upon receipt of this captured image, the difference value calculation unit 44 calculates the difference value with respect to the luminance value of each pixel forming the captured image (the luminance value of each image sensor) (S21), and uses the calculated difference value as a standard. Output to the deviation calculator 45.

  Upon receiving this difference value, the standard deviation calculation unit 45 calculates the standard deviation of the difference value (S22), and outputs the calculated standard deviation value to the defect detection unit 7 via the main control unit 5.

  Upon receiving this standard deviation value, the defect detection unit 7 compares the standard deviation value with a predetermined threshold value, and determines that a line defect exists if the standard deviation value is equal to or greater than the predetermined threshold value. (YES in S23), otherwise, it is determined to be a non-defective product (NO in S23).

(Fourth inspection method of the inspection apparatus 1)
Next, a fourth inspection method in the inspection apparatus 1 will be described with reference to FIGS. In the fourth inspection method, the brightness value of the image sensor is extracted from the captured image of the liquid crystal display panel 20 with respect to the arrangement of the same color picture elements at each pixel interval described later, and the standard deviation of the extracted brightness values is calculated. The maximum value of the standard deviation is calculated. Here, the picture element interval is another division adjacent to the arrangement direction of the same color picture elements (X-axis direction) from a certain part of the noticed division picture element (first part of the first division picture element). This is the distance to the part of the picture element corresponding to the first part (the first part of the second divided picture element), and is the distance expressed by the number of image sensors. In the example shown in FIGS. 4 and 7, one divided picture element is imaged by nine image sensors, and the number of these image sensors in the X-axis direction is three. Therefore, in this case, the pixel interval means a distance corresponding to three image sensors.

Specifically, the fourth inspection method includes the following processes.
1) Extract brightness values of a group of image sensors at positions separated by the pixel interval in the direction in which the same color picture elements are arranged in the captured image. Similar extraction is performed for image sensors adjacent in the X-axis direction, and this process is repeated at least until the next image sensor to be extracted is the same as the first image sensor. Hereinafter, the group of image sensors is referred to as a system. By the above processing, the same number of systems as the pixel interval are formed.
2) The standard deviation of the luminance values of each extracted system is calculated.
3) Select the largest standard deviation calculated for each system.
4) The maximum value of the standard deviation is compared with a predetermined threshold, and if the maximum value exceeds the threshold, it is determined that there is a defect.

  FIG. 15 shows the result of applying the above inspection method to the image sensor shown in FIG. FIG. 15 is a diagram illustrating a defect detection result obtained by the fourth inspection method in the inspection apparatus 1. In FIG. 7, only the image sensor corresponding to the image pickup device that images the defective portion shown in FIG. 7 and its periphery are shown.

  In the figure, the columns indicated by the arrows 31a, 31b, and 31c are the columns shown for each system by extracting the luminance of the image sensors separated by three image sensors that are the distances to the adjacent divided picture elements. The row of the arrow 31d indicates the result of calculating the standard deviation of the luminance value of each system. Furthermore, the line of the arrow 31e is the maximum value of three standard deviations derived from the three systems. The value indicated by the arrow 31f is a detected value of the line defect portion. A specific calculation example will be described below.

  In the captured image shown in FIG. 7, one divided picture element is captured by three image sensors in the X-axis direction. Therefore, the picture element interval is 3, and a group of three image sensor elements is formed. For example, in the case of a row of image sensors consisting of repetition of RR2, RR3, RR2, RR0, RR1, RR0, RR2 and RR0 form a first system, RR3 and RR1 form a second system, and RR2 A third system is formed by RR0.

  Then, the standard deviation of the extracted luminance values of each system is calculated. In the case of the first system, the standard deviation (R1-R0) / 6 is calculated from the luminance value (R1 / 3) of RR2 and the luminance value (R0 / 3) of RR0.

  Further, the maximum standard deviation ((R1-R0) / 2) calculated for the first to third systems is calculated. This maximum value is used as the detection value of the line defect portion.

  From the result shown in FIG. 15, the detection value ((R1-R0) / 2) of the line defect portion is larger than the detection value (5 (R1-R0) / 18) shown in FIG. It can be seen that it has improved.

  As described above, in the fourth inspection method, the interval between a plurality of same-color divided picture elements in a captured image obtained by picking up the liquid crystal panel 20, and a certain part of the noticed divided picture element (the first divided picture element first). The interval between one portion) and the portion corresponding to the first portion (the first portion of the second divided picture element) of the same color divided picture element adjacent to the first divided picture element is defined as a picture element interval. The fourth inspection method includes an extraction step of forming a luminance value system by extracting the luminance value of the imaging element for each pixel interval along the arrangement direction of the same color picture elements from the captured image; The standard deviation calculation step for calculating the standard deviation of the luminance value included in the luminance value system formed in the process for each luminance value system, and the maximum value of the standard deviation calculated in the standard deviation calculation step is the same color pixel. And a maximum value calculating step for calculating each array.

(Processing flow for performing the fourth inspection)
Next, a flow of processing for performing the above-described fourth inspection in the inspection apparatus 1, particularly the image conversion unit 4, will be described with reference to FIG. FIG. 16 is a flowchart showing a flow of processing for performing the fourth inspection in the inspection apparatus 1.

  A captured image of the liquid crystal display panel 20 captured by the camera 2 is input to the system division calculation unit 46 of the image conversion unit 4 via the main control unit 5.

Upon receiving this captured image, the system division calculation unit 46 extracts the luminance values of a group of image sensors (pixels of the captured image) located at positions separated by the pixel interval, so that the above-mentioned system is the same as the pixel interval. (Three systems in the above example) are formed (S31), and the luminance value of each formed system is output to the standard deviation calculation unit 45.

  Upon receiving these luminance values, the standard deviation calculation unit 45 calculates the standard deviation of the luminance values for each system (S32), and outputs the calculated standard deviation value to the maximum value calculation unit 47.

  Upon receiving these standard deviation values, the maximum value calculation unit 47 selects the maximum one of the standard deviation values (S33), and uses the maximum value via the main control unit 5 to detect the defect detection unit 7. Output to.

  Upon receiving the maximum value, the defect detection unit 7 compares the maximum value with a predetermined threshold, and determines that a line defect exists if the maximum value is equal to or greater than the predetermined threshold (YES in S34). Otherwise, it is determined to be a non-defective product (NO in S34).

(Effect of inspection device 1)
As described above, in the inspection apparatus 1, the ratio between the luminance value of a normal divided picture element and the luminance value of a divided picture element having a defect can be increased, and the detection sensitivity is higher than the defect detection by the conventional inspection method. Can detect line defects.

  In the inspection apparatus 1, the detection sensitivity from the vertical direction with respect to the surface of the liquid crystal display panel 20 is higher than human visual detection sensitivity.

  In human visual inspection, the panel surface is inspected not only from the vertical direction but also from the oblique direction. Depending on the brightness of the line defect, the visual recognition performance by oblique observation may be higher, so that from the viewpoint of inspection sensitivity, the detection sensitivity of the inspection apparatus 1 may not reach the visual inspection sensitivity. However, in this case, by changing the positional relationship between the camera 2 and the liquid crystal display panel 20 so that oblique observation is possible, it is possible to obtain inspection sensitivity equivalent to or higher than visual inspection sensitivity.

  Of the first to fourth inspection methods, the second inspection method in which the detected value of the line defect portion is the largest is most preferable.

(Example of change)
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in the embodiments. Is also included in the technical scope of the present invention.

  The image conversion unit 4 includes a difference absolute value calculation unit 41, an average value calculation unit 42, a maximum value filter calculation unit 43, a difference value calculation unit 44, a standard deviation calculation unit 45, a system division calculation unit 46, and a maximum value calculation unit 47. You don't have to have everything. Of these functional blocks, the image conversion unit 4 only needs to include a combination of functional blocks that can perform processing for realizing at least one of the first to fourth inspection methods. For example, in order to realize the first inspection method, the image conversion unit 4 only needs to include a difference absolute value calculation unit 41 and an average value calculation unit 42.

  By configuring a dedicated inspection circuit on the image processing board of the control device 3, parallel processing may be performed by hardware. As a result, when calculating only the average value as in the conventional inspection method, the absolute value is calculated after calculating the difference as in the first inspection method, and the average value is calculated in almost the same time. can do.

  The present invention can also be applied when one picture element is composed of three divided picture elements. In this case, the luminance value of the middle divided picture element is excluded from the processing target in the first to fourth inspection methods among the upper divided picture element, the middle divided picture element, and the lower divided picture element arranged in the arrangement direction of the same color picture elements. May be. With this configuration, the amount of calculation can be reduced, and the ratio between the luminance value of a normal divided picture element and the luminance value of a divided picture element having a defect can be increased.

  Further, each block of the inspection apparatus 1 described above, particularly each block of the image conversion unit 4 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the inspection apparatus 1 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, a RAM (random access memory) that expands the program, A storage device (recording medium) such as a memory for storing the program and various data is provided. The object of the present invention is to record the program code (execution format program, intermediate code program, source program) of the control program (image analysis program) of the inspection apparatus 1, which is software that realizes the above-described functions, in a computer-readable manner. This can also be achieved by supplying the recording medium to the inspection apparatus 1 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the inspection apparatus 1 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention can also be expressed as follows.

  The liquid crystal display panel inspection method of the present invention is a multi-domain liquid crystal display panel inspection in which a plurality of divided pixels of the same color are arranged in the same pixel, and is adjacent to the captured image in the arrangement direction of the same color pixels. The difference calculation process for calculating the absolute value of the luminance difference with the same color picture element to be executed is executed, the calculation process for calculating the average of the calculation values is executed next, and then the average value is orthogonal to the arrangement direction. A comparison process for comparing the directions is executed to extract line defects in the direction of the arrangement of the same color picture elements.

  In the inspection method, when the same-color picture elements adjacent to each other are separated by N elements in the captured image, the maximum value detection processing for the neighboring N-elements is performed in the arrangement direction. It is preferable to execute before the difference calculation process.

  Further, the difference calculation process is a process of calculating a luminance difference between adjacent color elements in the direction of the same color picture element, and the calculation process is a process of calculating a standard deviation of the calculated values. Is preferred.

  According to the liquid crystal display panel inspection method of the present invention, the same color picture elements are arranged in the arrangement direction with respect to the captured image, and the adjacent same color picture elements are separated by N elements in the captured image. An extraction process for extracting the value of the image sensor for each N element and dividing it into N element groups is performed. Next, a calculation process for calculating the standard deviation of each extracted element group is performed. A maximum value detection process for obtaining a maximum value from the standard deviation of N element groups extracted from the array of N is performed, and finally a comparison process for comparing the detected value with a direction orthogonal to the direction of the array is performed. A line defect in the direction in which the same color picture elements are arranged is extracted.

  Since defects of display panels, particularly multi-domain liquid crystal panels, can be detected with high detection sensitivity, the present invention can be applied to an inspection apparatus that inspects these display panels.

It is a functional block diagram which shows the structure of the control apparatus with which the liquid crystal display panel test | inspection apparatus of one Embodiment is provided. It is the schematic which shows the structure of the liquid crystal display panel test | inspection apparatus of one Embodiment. It is the schematic which shows arrangement | positioning of the division | segmentation picture element in a liquid crystal display panel of a multi domain system. It is a figure which shows allocation with respect to the pixel of a liquid crystal display panel of the image pick-up element which a camera has. It is a graph which shows the relationship between the setting luminance value of a liquid crystal display panel, and an actual luminance value. It is a figure which shows the brightness | luminance of each division | segmentation picture element at the time of liquid crystal display panel black lighting. It is a figure which shows the luminance value of each image pick-up element when imaging a liquid crystal display panel. It is a figure which shows the detection process result of the line defect by the conventional inspection method. It is a figure which shows the defect detection result by the 1st inspection method in the said inspection apparatus. It is a flowchart which shows the flow of the process for performing a 1st test | inspection in the said test | inspection apparatus. It is a figure which shows the defect detection result by the 2nd inspection method in an inspection apparatus. It is a flowchart which shows the flow of the process for performing a 2nd test | inspection in the said test | inspection apparatus. It is a figure which shows the defect detection result by the 3rd inspection method in the said inspection apparatus 1. FIG. It is a flowchart which shows the flow of the process for performing a 3rd test | inspection in the said inspection apparatus. It is a figure which shows the defect detection result by the 4th inspection method in the said inspection apparatus. It is a flowchart which shows the flow of the process for performing a 4th test | inspection in the said inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel inspection apparatus 2 Camera (imaging means)
4 Image converter (image analysis device)
7 Defect detection unit (defect detection means)
20 Liquid crystal display panel 21 Pixel 22a Split R picture element (same color picture element)
22c Split R picture element (same color picture element)
22d Split R picture element (same color picture element)
25 Image sensor 41 Difference absolute value calculation unit (difference absolute value calculation means)
42 Average value calculation unit (average value calculation means)
44 Difference value calculation unit (difference value calculation means)
45 Standard deviation calculator (standard deviation calculation means)
46 System division calculation part (extraction means)
47 Maximum value calculator (maximum value calculation means)

Claims (10)

An inspection apparatus that detects a defect in the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction by an imaging unit having an imaging element and analyzing a luminance value of the obtained captured image An image analysis method in an image analysis apparatus,
The absolute difference value for calculating the absolute value of the difference value between the luminance value of the target picture element included in the captured image and the luminance value of the same color picture element adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements A calculation process;
An average value calculating step of calculating an average value of the absolute values of the difference values calculated in the difference absolute value calculating step along an arrangement direction of the plurality of same-color picture elements. . An inspection apparatus that detects a defect in the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction by an imaging unit having an imaging element and analyzing a luminance value of the obtained captured image An image analysis method in an image analysis apparatus,
  A maximum luminance value calculating step of calculating a maximum value of luminance values of a plurality of imaging elements that have imaged a certain pixel with respect to the plurality of captured pixels;
  An absolute value of a difference value between the maximum value related to the target picture element and the maximum value related to the same color picture element adjacent to the target picture element is calculated for each column of the image pickup elements arranged in the arrangement direction of the same color picture element Difference absolute value calculation step,
  An average value calculating step of calculating an average value of the absolute values of the difference values calculated in the difference absolute value calculating step along an arrangement direction of the plurality of same-color picture elements. . An inspection apparatus that detects a defect in the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction by an imaging unit having an imaging element and analyzing a luminance value of the obtained captured image An image analysis method in an image analysis apparatus,
A difference value calculating step of calculating a difference value between the luminance value of the target picture element included in the captured image and the luminance value of the same color picture element adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements;
A standard deviation calculating step of calculating a standard deviation of the difference value calculated in the difference value calculating step for each column of image pickup devices arranged in an arrangement direction of the plurality of same-color picture elements. analysis method. An inspection apparatus that detects a defect in the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction by an imaging unit having an imaging element and analyzing a luminance value of the obtained captured image An image analysis method in an image analysis apparatus,
The interval between the plurality of same-color picture elements in the captured image, the target part of the target picture element and the target part of the same-color picture element adjacent to the target picture element in the arrangement direction of the plurality of same-color picture elements. When the interval between the corresponding parts is the pixel interval,
An extraction step of forming a group of luminance values by extracting the luminance value of the imaging element for each pixel interval along the arrangement direction of the plurality of same-color picture elements from the captured image;
A standard deviation calculating step for calculating the standard deviation of the luminance values included in the group of luminance values formed in the extracting step for each group of the luminance values;
And a maximum value calculating step of calculating a maximum value of the standard deviation calculated in the standard deviation calculating step for each of the plurality of columns of the same color picture element. An image in an inspection apparatus that detects a defect of the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction by an imaging means having an imaging element and analyzing a luminance value of the obtained captured image An analysis device,
The absolute difference value for calculating the absolute value of the difference value between the luminance value of the target picture element included in the captured image and the luminance value of the same color picture element adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements A calculation means;
An image analyzing apparatus comprising: an average value calculating means for calculating an average value of the absolute values of the difference values calculated by the difference absolute value calculating means along an arrangement direction of the plurality of same-color picture elements. . An inspection apparatus that detects a defect in the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction by an imaging unit having an imaging element and analyzing a luminance value of the obtained captured image An image analysis device,
A difference value calculating means for calculating a difference value between a luminance value of a target picture element included in the captured image and a luminance value of the same color picture element adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements;
An image comprising: a standard deviation calculating unit that calculates a standard deviation of the difference value calculated by the difference value calculating unit for each column of the imaging elements arranged in an arrangement direction of the plurality of same-color picture elements. Analysis device. An inspection apparatus that detects a defect in the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction by an imaging unit having an imaging element and analyzing a luminance value of the obtained captured image An image analysis device,
The interval between the plurality of same-color picture elements in the captured image, the target part of the target picture element and the target part of the same-color picture element adjacent to the target picture element in the arrangement direction of the plurality of same-color picture elements. When the interval between the corresponding parts is the pixel interval,
An extraction unit that forms a group of luminance values by extracting the luminance value of the imaging element for each pixel interval along the arrangement direction of the plurality of same-color pixels from the captured image;
A standard deviation calculating means for calculating, for each group of luminance values, a standard deviation of luminance values included in the group of luminance values formed by the extracting means;
An image analyzing apparatus comprising: a maximum value calculating means for calculating a maximum value of the standard deviation calculated by the standard deviation calculating means for each of the plurality of columns of the same color picture element. An inspection apparatus that detects a defect in the display panel by imaging a display panel in which a plurality of same-color picture elements are arranged in a certain direction with an imaging means having an imaging element and analyzing the luminance value of the obtained captured image. And
The image analysis apparatus according to any one of claims 5 to 7,
An inspection apparatus comprising: defect detection means for determining the presence or absence of a defect by comparing a luminance value of a picture element calculated by the image analysis apparatus with a predetermined threshold value.   The image analysis program for functioning a computer as said each means of the image analysis apparatus of any one of Claims 5-7.   A computer-readable recording medium on which the image analysis program according to claim 9 is recorded.

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