WO2008007729A1

WO2008007729A1 - Image analyzing method, image analyzing apparatus, inspecting apparatus, image analyzing program and computer readable recording medium

Info

Publication number: WO2008007729A1
Application number: PCT/JP2007/063887
Authority: WO
Inventors: Hiroyuki Nakai; Yasuhiro Ueda; Minoru Yasukawa; Minori Yamataka
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2006-07-13
Filing date: 2007-07-12
Publication date: 2008-01-17
Also published as: JP2008020369A; JP4143660B2

Abstract

A liquid crystal display panel inspecting apparatus (1) is provided with a differential absolute value calculating section (41) for calculating the absolute value of a differential value of the luminance value of a target pixel included in a picked up image and the luminance value of a same color pixel adjacent to the target pixel; and an average value calculating section (42), for calculating the average value of the absolute values of the differential values calculated by the differential absolute value calculating section (41) along an arranging direction of a plurality of the same color pixels. Thus, an image analyzing method, an image analyzing apparatus and an inspecting apparatus which can detect defects of the display panel at a high detection sensitivity are provided.

Description

Specification

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

Technical field

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 captured from the display panel, and a computer in which the image analysis program is recorded The present invention relates to a readable recording medium. Background art

In recent years, with the increase in size of liquid crystal display panels, the importance of automatic inspection has increased. In automatic inspection equipment, at least defects that are visible to the human eye must be detected, so detection sensitivity equivalent 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, 1) The human eye observes not only vertically but also obliquely with respect to the panel surface. 2) Because human visual processing is analog and the resolution in the luminance direction is high, 3) This is because human visual inspection is performed at a high resolution by using this part intensively when the spatial resolution at the center of the visual field is high.

[0004] Therefore, in an automatic inspection apparatus using a camera, it is necessary to improve detection sensitivity as much as possible by devising a device configuration and an algorithm.

[0005] Further, conventional liquid crystal display panels have been configured such that each pixel of each color is arranged in one pixel consisting of RGB. As described in the above, a plurality of divided picture elements are provided in one picture element, and the brightness of the intermediate gray level of the pixel is expressed more vigorously by changing the brightness of each divided picture element separately. Multi-domain liquid crystal display panels are now being used.

[0006] Regarding the detection of line defects, in the case of a conventional liquid crystal display panel, the brightness of each picture element in a line of same color picture elements having a line defect is different from the brightness of the picture element in the other line of same color picture elements. Is used to detect line defects. 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 value is added to the value. An algorithm has been used that detects a line having a value different from the surroundings as a line defect compared to the value related to the arrangement of the same color picture elements located in the direction orthogonal to the arrangement direction.

[0007] However, for a multi-domain liquid crystal panel, the luminance power of the divided picture elements in the line defect portion is different for each divided picture element. As an example of a multi-domain liquid crystal panel, one picture element (for example, R1) consists of two parts (upper and lower parts). (Rlup) brightness changes, the brightness of the lower part (Rllow) changes from 128 to 256, and the upper and lower parts of the adjacent R pixels are in the same order in the direction of Rlup-Rllow. (ROup—ROlow—Rlup—Rllow—RSup—RSlow). In this case, if there is a line defect, the luminance changes alternately in one line of the same color picture element, with black lighting or white lighting.

[0008] Therefore, a line defect is detected by using the fact that the luminance pattern of the divided picture elements constituting the picture element is different in the line defect part that is obtained by simply adding the luminance values of the picture elements in the direction in which the same color picture elements are arranged. A way to do this is conceivable.

Patent Document 1: Japanese Published Patent Publication “Japanese Patent Laid-Open No. 04-102830 (Publication Date: April 3, 1992)”

Patent Document 2: Japanese Published Patent Publication “JP 07-181451 Publication Date (July 21, 1995)”

Patent Document 3: Japanese Patent Publication “Japanese Patent Laid-Open No. 08-184834 (Publication Date: July 16, 1996)”

Patent Document 4: Japanese Patent Publication “Japanese Patent Laid-Open No. 10-240933 (Publication Date: September 11, 1998)”

Disclosure of the invention

[0009] However, in the conventional line defect detection algorithm described above, the difference between the detected values of the defective portion and the non-defective portion and the luminance value of each non-defective portion also vary, so that the defect is extracted. The problem is that the detection sensitivity is not obtained and defects cannot be separated.

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

[0011] In order to solve the above problems, 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 by an imaging means having an imaging element, and obtains the obtained 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 luminance value of an image, the luminance value of a target pixel included in the captured image, and the plurality of In the arrangement direction of the same-color picture element !, the absolute difference calculation process for calculating the absolute value of the difference between the brightness value of the same-color picture element adjacent to the target picture element, and the difference absolute value calculation process. And an average value calculating step of calculating an average value of absolute values of the difference values along the arrangement direction of the plurality of same-color picture elements.

In order to solve the above problems, an 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 obtains the obtained image An image analysis apparatus in an inspection apparatus that detects a defect of the display panel by analyzing a luminance value of an image, the luminance value of a pixel of interest included in the captured image, and an array of the plurality of same-color pixels A difference absolute value calculating means for calculating an absolute value of a difference value between a luminance value of the same color pixel adjacent to the target picture element in the direction, and an absolute value of the difference value calculated by the difference absolute value calculating means. An average value calculating means for calculating an average value along the arrangement direction of the plurality of same-color picture elements is provided.

[0013] In the conventional configuration, 1) calculate the average value (first average value) of the luminance values of the pixels in the same color pixel row of interest in the image captured from the display panel, and 2) the first average Calculate the average value (second average value) of the luminance values in the same color pixel column that is different from the same color pixel column for which the value was calculated, and calculate the difference value between the first average value and the second average value To do.

[0014] On the other hand, according to the configuration of the present invention, the absolute difference calculation means calculates the luminance value of the pixel of interest from among the plurality of same-color picture elements arranged in a fixed direction, and the same-color picture element. The absolute value of the difference value from the luminance value of the picture element adjacent to the target picture element in the arrangement direction is calculated for the same color picture element column. Then, the average value calculating means calculates the average value along the arrangement direction of the same color picture elements from the absolute value of the difference value calculated by the difference absolute value calculating means.

[0015] When a line defect occurs in a column of the same color picture element, the column is compared with a normal column that is not a line defect. In comparison, a picture element with normal luminance and a picture element with abnormal luminance are mixed.

[0016] Therefore, when there is a line defect in a column of a certain same-color picture element, the luminance value in the normal luminance picture element and the luminance value in the abnormal luminance picture element in the column as described above. By calculating the difference between and, 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 an inspection apparatus, it is possible to realize an inspection apparatus that can detect defects in the display panel with high detection sensitivity.

[0018] 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 picture elements.

[0019] Further, in the image analysis method, a maximum luminance value calculating step of calculating a maximum value of luminance values of a plurality of imaging elements that have captured a target pixel for each column of imaging elements arranged in the arrangement direction. Before the difference absolute value calculating step, and in the difference absolute value calculating step, the absolute value of the difference value between the maximum value related to the pixel of interest and the maximum value related to the same color pixel adjacent to the pixel. Is preferably calculated for each column of the image sensor.

[0020] 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, in the maximum luminance value calculation step, the maximum one of the luminance values of the plurality of image sensors (pixels) that captured the target pixel is calculated for each column of the image sensors arranged in the same color pixel arrangement direction. To do. In the difference absolute value calculation step, the absolute value of the difference value between the maximum value related to the pixel of interest and the maximum value related to the same color pixel adjacent to the pixel is calculated for each column of the image sensor. .

[0021] As described above, by obtaining the maximum value of the luminance values of a plurality of imaging elements that have imaged the target pixel, the luminance value in the normal luminance pixel and the luminance value in the abnormal luminance pixel are calculated. The ratio can be further increased, and the defect detection sensitivity can be increased as compared with the case of calculating the luminance value of the entire pixel of interest.

[0022] In order to solve the above problems, an image analysis method according to the present invention is obtained 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. 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 luminance value of a captured image, the luminance value of a target pixel included in the captured image, and In the arrangement direction of 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 picture element and the difference value calculation step calculated above And a standard deviation calculating step of calculating a standard deviation of the difference value for each column of the image pickup elements arranged in 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 obtains the obtained image An image analysis apparatus included in an inspection device that detects a defect of the display panel by analyzing a luminance value of an image, the luminance value of a pixel of interest included in the captured image, and the plurality of same-color pixel elements A difference value calculating means for calculating a difference value between luminance values of the same color picture element adjacent to the target picture element in the arrangement direction, and a standard deviation of the difference value calculated by the difference value calculating means, And standard deviation calculating means for calculating for each column of image pickup devices arranged in the arrangement direction of the same color picture elements.

[0024] According to the above configuration, the difference value calculating means calculates the difference value between the luminance value of the target picture element and the luminance value of the same color picture element adjacent to the target picture element, and the standard deviation calculating means is Then, the standard deviation of the difference value is calculated for each column of the image sensors arranged in the arrangement direction of the same color picture elements.

[0025] By calculating the standard deviation of the difference value as described above, 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. 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.

[0027] 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 by an imaging unit having an imaging element, and obtains the obtained 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 luminance value of an image, the image analysis method including: The interval between the plurality of same-color picture elements, the portion corresponding to the target portion of the target pixel of the target pixel and the same-color pixel adjacent to the target pixel in the arrangement direction of the plurality of same-color pixels. When the pixel interval is defined as the pixel interval, the luminance value of the image sensor is extracted for each pixel interval along the arrangement direction of the plurality of same-color pixels from the captured image. An extraction step for forming a group of luminance values, a standard deviation calculation step for calculating the standard deviation of luminance values included in the luminance value group formed in the extraction step for each group of luminance values, and the calculation of the standard deviation And a maximum value calculating step for calculating the maximum value of the standard deviation calculated in the process for each of the plurality of columns of the same color picture element.

[0028] In order to solve the above problems, 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 means having an imaging element, and obtains the obtained image. An image analysis apparatus included in an inspection apparatus that detects a defect of the display panel by analyzing a luminance value of an image, the interval between the plurality of same-color picture elements in the captured image, When the interval between the portion and the portion corresponding to the target portion of the same color pixel adjacent to the target pixel in the arrangement direction of the plurality of same color pixels is defined as the pixel interval, The extraction means 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 the same color picture elements, and the extraction means Brightness included in the group of luminance values A standard deviation calculating means for calculating the standard deviation of the degree value for each group of the luminance values, and a maximum value for calculating the maximum standard deviation calculated by the standard deviation calculating means for each of the plurality of columns of the same color And a value calculating means.

[0029] According to the above configuration, the extraction unit extracts the luminance value of the image sensor (pixel) for each pixel interval along the arrangement direction of the same color pixels from the captured image of the display panel. A group of brightness values is formed. In other words, this group of luminance values is a set of luminance values of an image pickup element that has picked 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.

[0030] 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. Calculate for each row of pixels of the same color. [0031] As described above, by obtaining the maximum value of the standard deviation of the luminance values included in the luminance value group, the luminance value in the pixel of the normal luminance value and the luminance deviating from the normal luminance value range power. The ratio with the luminance value of the defective pixel having the 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.

[0033] Further, 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 device, and the luminance value of the obtained captured image is analyzed to thereby detect the defect in the display panel. An inspection apparatus for detecting the image analysis apparatus, and a defect detection means for determining the presence / absence of a defect by comparing a luminance value of a pixel calculated by the image analysis apparatus with a predetermined threshold value. An inspection apparatus including the above is also included in the technical scope of the present invention.

[0034] In this case, the image analysis apparatus may be realized by a computer. In this case, the image analysis apparatus that realizes the image analysis apparatus by a computer by causing the computer to operate as the respective means. A control program (image analysis program) and a computer-readable recording medium on which the control program is recorded are also included in the technical scope of the present invention.

[0035] Other objects, features, and advantages of the present invention will be fully understood from the following description. The advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

Brief Description of Drawings

FIG. 1 is a functional block diagram showing a configuration of a control device included in a liquid crystal display panel inspection device according to an embodiment.

FIG. 2 is a schematic diagram showing a configuration of a liquid crystal display panel inspection apparatus according to an embodiment.

FIG. 3 is a schematic diagram showing an arrangement of divided picture elements in a multi-domain liquid crystal display panel.

FIG. 4 is a diagram showing the allocation of the image sensor of the camera to the pixels of the liquid crystal display panel. FIG. 5 is a graph showing the relationship between the set luminance value of the liquid crystal display panel and the actual luminance value.

FIG. 6 is a diagram showing the luminance of each divided picture element when the liquid crystal display panel is lit black.

FIG. 7 is a diagram showing the luminance value of each image sensor when a liquid crystal display panel is imaged.

FIG. 8 is a diagram showing a result of detection processing of line defects by a conventional inspection method.

FIG. 9 is a diagram showing a defect detection result by the first inspection method in the inspection apparatus.

FIG. 10 is a flowchart showing the flow of processing for performing the first inspection in the inspection apparatus.

FIG. 11 is a diagram showing a defect detection result by a second inspection method in the inspection apparatus.

FIG. 12 is a flowchart showing a flow of processing for performing a second inspection in the inspection apparatus.

FIG. 13 is a diagram showing a defect detection result by a third inspection method in the inspection apparatus 1

FIG. 14 is a flow chart showing a flow of processing for performing a third inspection in the inspection apparatus.

FIG. 15 is a diagram showing a defect detection result by a fourth inspection method in the inspection apparatus.

FIG. 16 is a flowchart showing the flow of processing for performing a fourth inspection in the inspection apparatus.

Explanation of symbols

1 LCD panel inspection equipment

2 Camera (imaging means)

4 Image converter (image analyzer)

7 Defect detection unit (defect detection means)

20 LCD panel (display panel)

21 pixels

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 section (Absolute difference calculation means)

42 Average value calculator (mean value calculation means)

44 Difference value calculation unit (Difference value calculation means)

45 Standard deviation calculator (Standard deviation calculation means)

46 System division calculation unit (extraction means)

47 Maximum value calculator (Maximum value calculation means)

BEST MODE FOR CARRYING OUT THE INVENTION

[0038] An embodiment of the present invention will be described with reference to Figs. 1 to 16 as follows.

[0039] (Configuration of Liquid Crystal Display Panel Inspection Apparatus 1)

The liquid crystal display panel inspection apparatus 1 (hereinafter referred to as 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 by an imaging means having an imaging element, and the brightness of the obtained captured image The display panel defect is detected by analyzing the values, and the display panel defect is detected by the first to fourth inspection methods described later.

[0040] In the following description, the display panel defect specifically means a picture element having a luminance value out of a predetermined range force among a plurality of picture elements constituting the display panel.

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

[0042] 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.

[0043] 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.

The 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 picked up by the camera 2, and the picked-up image is sent to the control device 3 and processed by a predetermined algorithm. It is.

As will be described later, the inspection apparatus 1 includes the illumination 11 and the lighting circuit 12. However, these members are omitted in FIG.

[0046] (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.

[0047] The image conversion unit 4 performs processing 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.

[0049] The storage unit 6 stores various setting values used in the inspection apparatus 1.

The main controller 5 writes and reads information.

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.

[0051] The display unit 8 displays inspection conditions, inspection results, and the like, and the input unit 9 receives operation of the inspection apparatus 1 by an operator. Which of the first to fourth inspection methods to be described later is used for the inspection is designated by the operator via the input unit 9.

[0052] (Configuration of 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, a difference value calculation unit. 4 4 (Difference value calculation means), Standard deviation calculation section 45 (Standard deviation calculation means), System division calculation section 4 6 (Extraction means), Maximum value calculation section 47 (Maximum value calculation means) .

[0053] The difference absolute value calculation unit 41 determines the luminance value of the divided pixel of interest (for example, the R pixel 22a in FIG. 6) and the same-color divided pixel (for example, in FIG. 6) adjacent to the pixel. R picture element 22b) The absolute value of the difference value is calculated with respect to the same color picture element sequence (R picture element, G picture element or B picture element sequence).

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.

[0055] 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. To do.

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

[0057] The standard deviation calculation unit 45 calculates the standard deviation of the difference value calculated by the difference value calculation unit 44.

The calculation is performed for each column of image sensors arranged in the arrangement direction of the same color picture elements.

[0058] From the captured image of the liquid crystal display panel 20, the system division calculation unit 46 performs the brightness value of the image sensor (the brightness value of the pixel of the captured image) for each pixel interval to be described later along the arrangement direction of the same color picture elements. By extracting, a group of luminance values (system) is formed.

[0059] The maximum value calculation unit 47 calculates the standard deviation of the luminance values included in the system, which is 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.

[0061] (Configuration of liquid crystal display 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, this is a multi-domain liquid crystal display panel in which a plurality of divided picture elements are provided in one picture element and the luminance of each divided picture element is changed separately.

Note that the inspection target 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 picture elements constituting line defects 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 The pixel 21 also has the power of RGB three-color picture elements (R picture element 22, G picture element 23, B picture element 24), and these picture elements are further divided into smaller divided picture elements. Specifically, R picture element 22 is divided into divided R picture element 22a and divided R picture element 22b, G picture element 23 is divided into G picture element 23a, divided G picture element 23b, and B picture element 24 is divided. It is divided into B picture element 24a and divided B picture element 24b.

[0064] 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 element, G picture element, and B picture element). RU

[0065] In FIG. 3, the powers in which alphabets are written on each divided picture element. Each divided picture element indicates a divided picture element in which R is red, G is green, and B is blue. In the following explanation, the case where one picture element consists 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.

[0066] (Correspondence between image sensor 25 and pixel 21)

FIG. 4 is a diagram showing the allocation of the image sensor of the camera 2 to the pixel 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 that assigns a predetermined number of image sensors 25 to the pixels 21 of the liquid crystal display panel 20. In the case shown in FIG. 4, the image sensor 25 is assigned 6 × 6 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 a larger number of image sensors be allocated.

[0067] (Problems of conventional inspection methods)

Here, problems of the conventional inspection method will be described.

The relationship between the brightness setting value and the actual brightness 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, in the inspection of liquid crystal display panels that are lit at intermediate gray levels, where the change in the actual luminance value is large relative to the change in the luminance setting, the detection accuracy is relatively high even with conventional inspection algorithms. It is possible to obtain.

[0069] In contrast, in the black lighting inspection and the white lighting inspection, since the gradient of the luminance value with respect to the luminance setting value is small and the change in the luminance value is small, it is difficult to detect a minute change in the luminance setting. Therefore, the conventional method may not have sufficient sensitivity to obtain sufficient defect detection accuracy.

Therefore, the panel inspection method of 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.

[0071] (Conventional inspection method in black lighting inspection)

Next, a conventional inspection method in the black lighting inspection will be described.

FIG. 6 shows a line defect 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 in the alphabet written on each divided picture element. As shown in the figure, when the black R is lit, the divided R picture elements 22a and 22b have the same brightness (luminance value 0). Since only the divided R picture element 22c which is a picture element is lit, the luminance value of the divided R picture element 22c is different from that of the divided R picture element 22d which is the same color picture element adjacent to the divided R picture element 22c. If the luminance of the divided R picture element 22c is R1, and the luminance of the divided R picture element 22d is RO, the pattern of this 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 showing 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 the luminance value of the pixels forming the captured image obtained by imaging the liquid crystal display panel 20. BR denotes 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 image area including no picture elements other than the divided R picture element.

In FIG. 7, the image pickup element 25 shown in white is an image of a divided R pixel having a bright spot defect.

[0075] 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 It is expressed by a formula. BR0 = = BO / 94 -RO / 9

BR1 = = BO / 64 -R0 / 6

RR0 = = RO / 3

RR1 = = RO

RGO = RO / 9- hGO / 9

RGl: = R0 / 6- hG0 / 6

GGO = GO / 3

GG1 = GO

GBO: = GO / 9- f BO / 9

GBl: = G0 / 6- f BO / 6

BBO = = BO / 3

BB1 = = BO

BR2 = = BO / 94 -Rl / 9

BR3 = = BO / 64 -Rl / 6

RR2 = = Rl / 3

RR3 = = R1

RG2: = Rl / 9- hRO / 9

RG3 = Rl / 6- hR0 / 6

In the conventional inspection method, inspection is performed in the following three stages.

1) Calculate the average value (first average value) of the brightness values of the image sensor in the direction in which the same color picture elements are lined up in the captured image (X-axis direction).

2) Calculate the average value (second average value) of the corresponding luminance values of the same color pixels in adjacent pixels in the direction (Y-axis direction) orthogonal to the above-mentioned arrangement direction. 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, but the luminance values of the image sensor in the direction in which the same color picture elements are arranged (X-axis direction) may be added. These are the same 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 figure, the line indicated by the arrow 27a shows the result of calculating the average of the luminance values in the direction of the same color picture elements (X-axis direction). The row indicated by the arrow 27b is a row of the same-color picture elements located at a position separated by six image sensors in the Y-axis direction from the above-mentioned average value and the same-color picture element row for which the average value was calculated. This is the difference between the average value of the luminance values of the same color picture elements in adjacent pixels. In addition, when the difference value is negative, 0 is indicated. The value of the line indicated by the arrow 27c in the row of the arrow 27b becomes the detected value of the line defect. That is, the average value of the luminance values in the arrangement of the same color picture elements having the line defect is 5 (R0 + R1) Z18, and the difference value is 5 (R1−R0) Z18.

[0079] (First inspection method of inspection apparatus 1)

On the other hand, in the inspection apparatus 1, the first inspection is performed by the following three steps.

1) In the captured image of the liquid crystal display panel 20, the brightness of the imaging element that captured the target divided picture element and the division adjacent to 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 brightness of the image sensor that picked up the picture element 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 if the difference absolute average value exceeds the threshold value, it is determined that there is a defect.

FIG. 9 shows values calculated by the above processing. FIG. 9 is a diagram showing a defect detection result obtained by the first inspection method in the inspection apparatus 1. In the figure, only the line-up and the vicinity of the line defect of the image sensor shown in FIG. 6 are shown.

[0081] The column indicated by the arrow 28a indicates the luminance value of the image sensor that has captured the divided picture element of interest and the same value adjacent to the divided picture element at a position separated by three image sensors from the image sensor. The absolute value of the difference with the luminance value of the image pick-up element corresponding to the division | segmentation pixel of a color is shown. The line indicated by the arrow 28b shows the value obtained by averaging the absolute values of the differences in the direction of the same color picture elements (difference absolute average value). The arrow 28c in the row of this arrow 28b That is, the line value indicated by 5 | R1−RO | / 9 is the detected value of the line defect. In other words, it is preferable to calculate the detected value of the luminance value line defect of the image sensor that has the largest area in which the divided picture element is imaged among a plurality of image sensors that have imaged the divided picture element of interest.

[0082] Comparing the detection value in FIG. 8 (5 (R1—R0) Z18) with the detection value in FIG. 9 (5 | R1 -RO | / 9), the inspection device 1 detects the location of the line defect. The value is twice that of the conventional method, indicating that the detection sensitivity is improved.

[0083] In the case of white lighting and intermediate gradation, only the actual values of the brightness RO, GO, BO, and R1 of the divided picture elements in the liquid crystal display panel 20 change. The same as in the case of black lighting. 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.

[0084] As described above, the first inspection method corresponds to the luminance value of the imaging element obtained by imaging a part of the divided picture element of interest and the part of the same-color divided picture element adjacent to the divided picture element. A difference absolute value calculation step for calculating the absolute value of the difference value with respect to the luminance value of the imaging element that captured the portion for the plurality of same-color divided pixels, and the difference absolute value calculation step described above. An average value calculating step of calculating an average value of absolute values of the difference values along the arrangement direction of the plurality of same-color divided picture elements.

[0085] (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.

The 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.

[0087] Upon receiving this captured image, the difference absolute value calculation unit 41 calculates the absolute value of the difference described above from the brightness value of each pixel of the captured image (the brightness value of each image sensor) (S1), The absolute value of the calculated difference is output to the average value calculator 42.

[0088] Upon receiving the absolute value of the difference, the average value calculation unit 42 calculates the absolute value of the difference from the absolute value. The calculated absolute difference average is calculated (S2). Then, the average value calculation unit 42 outputs the calculated difference absolute average value to the defect detection unit 7 via the main control unit 5.

[0089] Upon receiving the absolute difference average value, the defect detector 7 compares the absolute difference average value with a predetermined threshold value, and if the absolute difference average value is equal to or greater than the predetermined threshold value, a line defect exists. If it is determined to be good (YES in S3), otherwise it is determined to be non-defective (NO in S3).

[0090] (Second inspection method of inspection apparatus 1)

Next, the second inspection method in the inspection apparatus 1 will be described with reference to FIGS. The second inspection method is the direction in which the same color picture elements of the brightness value of the image sensor that captured the segmented pixel of interest are aligned with the captured image shown in FIG. 7 before the inspection by the first inspection method. A filter function for obtaining the maximum value at is applied.

[0091] Specifically, the second inspection method includes the following four stages of processing.

1) With respect to the direction in which the same color picture elements are lined up (X-axis direction), the divided pixel power adjacent to the target divided picture element is converted into an image sensor, and is located at a position separated by N image sensors from the divided pixel element. When

In other words, when one divided picture element is captured by N image sensors in the X-axis direction, the maximum value of the luminance values of the N image sensors in the X-axis direction of the divided picture element of interest is calculated. The obtained maximum value filter function is applied to the luminance value of each image sensor (maximum luminance value calculation step).

2) For a captured image having a luminance value subjected to the maximum value filter function, the segmentation in the direction in which the same color picture elements are lined up (X-axis direction) with the luminance of the image sensor that captured the segmented pixel of interest. The absolute value of the difference from the luminance of the image sensor that captured the divided picture element adjacent to the picture element is calculated (difference absolute value calculating step).

3) Calculate the average value (absolute difference average value) of the absolute values of the above differences in the direction (X-axis direction) of the divided picture elements.

4) The difference absolute average value is compared with a predetermined threshold value, and if the difference absolute average value exceeds the threshold value, it is determined that there is a defect.

The values calculated by the above process 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 same figure, only the line with the line defect of the image sensor shown in FIG. 7 and the vicinity thereof are shown. [0093] In FIG. 11, the column indicated by the arrow 29a is the value of each image sensor generated after performing the above-described processing for obtaining the maximum value, and the column of the arrow 29b is 3 images for the maximum value. This is a value obtained by calculating the absolute value of the difference from the luminance value at the position of the adjacent same-color divided picture element separated by the element. Furthermore, the line indicated by the arrow 29c is the average of the absolute values of the differences calculated along the arrangement of the same color pixels. A specific calculation example will be described below.

In the captured image shown in FIG. 7, one divided picture element is picked up by three image pickup elements in the X-axis direction. For example, in the case of a divided R picture element having a bright spot defect, the central part is imaged by a row of image sensors consisting 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) possessed by RR3. Therefore, the brightness values of RR2, RR3, and RR2 are all converted to R1.

[0095] In the case of RR3, the difference between the luminance value (R1) of RR3 and the luminance value (RO) of RR1, which is an image sensor located at a position away from the RR3 by three image sensors in the X-axis direction. The absolute value (I Rl -RO I) is calculated.

[0096] Further, the average value of the absolute values of the differences in the row of imaging elements arranged in the X-axis direction (

I Rl -RO I) is calculated. This average value is used as a detection value of the line defect portion.

In FIG. 11, the detected value (I Rl—RO |) of the line defect indicated by the arrow 29c is larger than the detected value (5 I Rl −RO I / 9) shown in FIG. I understand that.

[0098] As described above, the second inspection method is as follows: 1) An image sensor that arranges the maximum luminance value of a plurality of imaging elements that have captured the target divided picture element in the arrangement direction of the divided picture elements. 2) calculating the absolute value of the difference between the maximum value relating to the segmented pixel of interest and the maximum value relating to the same color segmented pixel adjacent to the segmented pixel; And a difference absolute value calculating step for calculating for each column of the image sensor.

[0099] (Process flow for performing second inspection)

Next, the 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. The 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.

[0101] Upon receiving this captured image, the maximum value filter calculation unit 43 performs the above-described maximum value filter function on the luminance value of each pixel forming the captured image (the luminance value of each image sensor) (

S11), and outputs the calculated luminance value to the difference absolute value calculation unit 41.

[0102] Since the subsequent processing flow is the same as the processing flow for performing the first inspection described above, description thereof is omitted.

[0103] (Third inspection method of 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 image pickup elements corresponding to the divided picture elements adjacent in the direction in which the same color picture elements are arranged in the picked-up 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.

[0104] Specifically, the third inspection method includes the following processes.

1) In the captured image, the difference value between the luminances of the image pickup 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 calculating step).

2) Next, the average value of the difference values of the image sensors arranged in the X-axis direction is calculated, and the standard deviation of the difference value is calculated (standard deviation calculation step).

3) The standard deviation value is compared with a predetermined threshold value, and if the standard deviation value exceeds the threshold value V, it is determined that there is a defect.

[0105] 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 showing a defect detection result obtained by the third inspection method in the inspection apparatus 1.

[0106] In the drawing, only the image sensor corresponding to the imaging device shown in Fig. 7 and the periphery thereof 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 indicates the standard deviation in the direction of the arrangement of the same color pixels. The result of calculation is shown. A specific calculation example is described below. In the captured image shown in FIG. 7, one divided picture element is picked up by three image pickup elements in the X-axis direction. For example, in the case of a divided R picture element having a bright spot defect, the central part is imaged by a row of image sensors consisting of RR2, RR3, and RR2.

[0108] In the case of RR3, the difference value (RO) between the luminance value (R1) of RR3 and the luminance value (RO) 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) is calculated.

[0109] Then, the standard deviation of the difference values in the image sensor columns (RR2, RR3, RR2, RRO, RR1, and RRO repetition force) arranged in the X-axis direction, including the image sensor columns, is Calculated. The value of this standard deviation is used as a detection value for the line defect portion.

[0110] As shown in FIG. 13, the detected value of the line defect part by the third inspection method indicated by the arrow 30c (the value obtained by multiplying the square root of 33 by (R1-RO) divided by 9) is It can be seen that the detection value is larger than the detection value (5 (R1-R0) Z18) shown in FIG. 8, and the detection sensitivity is improved.

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

[0112] (Process flow for performing the third inspection)

Next, the 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.

[0113] The 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.

[0114] Upon receiving this captured image, the difference value calculation unit 44 calculates the difference value with respect to the luminance value (the luminance value of each image sensor) of each pixel forming the captured image (S21). The difference value is output to the standard deviation calculator 45.

[0115] Upon receiving this difference value, the standard deviation calculation unit 45 calculates the standard deviation of the difference value.

(S22) The calculated standard deviation value is output to the defect detection unit 7 via the main control unit 5.

[0116] Upon receiving this standard deviation value, the defect detection unit 7 determines that the standard deviation value and a predetermined threshold value are used. If the standard deviation value is equal to or greater than the specified threshold value, it is determined that a line defect exists (YES in S23), otherwise it is determined to be a non-defective product (NO in S23). .

[0117] (Fourth inspection method for 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 at each pixel interval, which will be described later, with respect to the arrangement of the same-color picture elements, 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 a part of the divided picture element of interest (the first part of the first divided picture element) and another divided adjacent to the arrangement direction of the same color picture elements (X-axis direction). 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 the distance of three image sensors.

[0118] Specifically, the fourth inspection method includes the following processes.

1) Extract the luminance values of a group of image sensors at a position separated by the pixel interval in the direction in which the same color picture elements are arranged in the captured image. The same extraction is performed for image pickup elements adjacent in the X-axis direction, and this process is repeated at least until the next image pickup element is the same as the one extracted first. Hereinafter, the group of image pickup devices is referred to as a system. By the above processing, the same number of systems as the pixel interval are formed.

2) Calculate the standard deviation of the brightness values of each extracted system.

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 the figure, only the image sensor corresponding to the image pickup device that images the defective portion shown in FIG. 7 and its periphery are shown.

[0120] In FIG. 15, the columns indicated by the arrows 31a, 31b, and 31c indicate the adjacent divided picture elements. The brightness of image sensors separated by three image sensors, which are distances, is extracted and shown in each column. The row of arrow 31d shows the result of calculating the standard deviation of the brightness values of each system. is there. Furthermore, the line of arrow 31e is the maximum 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 is described below.

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

[0122] Then, the standard deviation of the luminance values of each extracted system is calculated. In the case of the first system, the standard deviation (R1-RO) Z6 is calculated from the luminance value of RR2 (R1Z3) and the luminance value of RRO (ROZ3).

[0123] Further, the maximum value ((Rl-RO) / 2) of the standard deviation calculated in the first to third systems is calculated. This maximum value is used as the detection value of the line defect portion.

[0124] From the results shown in FIG. 15, the detected value ((R1-R0) Z2) force of the line defect part is detected as shown in FIG.

It is larger than (5 (R1-R0) Z18), and it can be seen that the detection sensitivity is improved.

[0125] As described above, in the fourth inspection method, there is an interval between a plurality of same-color divided picture elements in a captured image obtained by imaging the liquid crystal display panel 20, and a certain part of the noticed divided picture element (first The interval between the first part of one divided picture element) and the part corresponding to the first part of the same-color divided picture element adjacent to the first divided picture element (first part of the second divided picture element) It is a prime interval. The fourth detection 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 pixels from the captured image, and In the extraction process, the standard deviation calculation step for calculating the standard deviation of the luminance values included in the luminance value system formed for each luminance value system, and the standard deviation calculated in the standard deviation calculation process are calculated. And a maximum value calculating step for calculating a maximum value for each array of the same color picture elements.

[0126] (Process 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.

[0127] The 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.

[0128] Upon receiving this captured image, the system division calculation unit 46 extracts the luminance value of the group of image sensors (pixels of the captured image) at positions separated by the pixel interval, thereby representing the above system. The same number as the prime interval (three systems in the above example) is formed (S31), and the luminance value of each formed system is output to the standard deviation calculator 45.

[0129] 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. .

[0130] Upon receiving these standard deviation values, the maximum value calculation unit 47 selects the maximum one of the standard deviation values (S33), and the maximum value is sent via the main control unit 5. Output to defect detection unit 7.

[0131] Upon receiving the maximum value, the defect detection unit 7 compares the maximum value with a predetermined threshold value, and determines that a line defect exists if the maximum value is equal to or greater than the predetermined threshold value (in S34). YE S), otherwise, it is determined to be a non-defective product (NO in S34).

[0132] (Effect of inspection device 1)

As described above, in the inspection apparatus 1, the ratio between the luminance value of the normal divided picture element and the luminance value of the divided picture element having a defect can be increased, which is higher than the defect detection by the conventional inspection method. Line defects can be detected with detection sensitivity.

In the inspection apparatus 1, regarding the detection sensitivity from the vertical direction with respect to the surface of the liquid crystal display panel 20, a detection sensitivity higher than that of human eyes can be obtained.

[0134] In human visual inspection, inspection is performed not only from the direction perpendicular to the panel surface but also from an oblique direction. Depending on the brightness of the line defect, the visual recognition performance by oblique observation may be higher, so 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, inspection sensitivity equal to or better than visual inspection sensitivity can be achieved. It is possible to obtain.

[0135] 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.

[0136] (Modification example)

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

[0137] 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. It is not necessary to have all of part 47. 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.

[0138] By configuring a dedicated inspection circuit on the image processing board of the control device 3, parallel processing may be performed with a hard- er. 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.

[0139] The present invention can also be applied when one picture element has three divided picture element forces. In this case, out of the upper divided picture element, middle divided picture element, and lower divided picture element that are arranged in the same color picture element arrangement direction, the luminance value of the middle divided picture element is determined from the processing target in the first to fourth inspection methods. May be removed. 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.

[0140] 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 realized by software using a CPU as follows. May be.

[0141] That is, the inspection apparatus 1 has a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) in the upper d program, A RAM (random access memory) for developing the program and a storage device (recording medium) such as a memory for storing the program and various data are provided. The object of the present invention is to read 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 functions described above, with a computer. This can also be achieved by supplying a recording medium recorded as possible to the inspection apparatus 1 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

[0142] The recording medium includes, for example, a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy disk Z hard disk, and an optical disk such as CD-ROMZMOZ MD / DVD / CD-R. Disk systems, IC cards (including memory cards) Z optical cards and other card systems, or mask ROMZEPROMZEEPROMZ flash ROM and other semiconductor memory systems can be used.

[0143] 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. In addition, the transmission medium constituting the communication network is not particularly limited. For example, in the case of wired communication such as IEEE1394, USB, power line carrier, cable TV line, telephone line, ADSL line, infrared rays such as IrDA and remote control, Bluetooth (registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, and terrestrial digital network 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.

[0144] The present invention can also be expressed as follows.

[0145] The method for inspecting a liquid crystal display panel according to the present invention is the same for a picked-up image in 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. Execute difference calculation processing to calculate the absolute value of the luminance difference between adjacent pixels of the same color in the line direction, then execute calculation processing to calculate the average of the calculated values, and then the average A comparison process for comparing values in a direction orthogonal to the direction of the arrangement is executed to extract line defects in the arrangement direction of the same color picture elements.

[0146] Further, in the arrangement direction of the same-color picture elements, the inspection method is arranged in the arrangement direction when adjacent same-color picture elements are separated from the captured image by N elements. Therefore, it is preferable to execute the maximum value detection process for neighboring N elements before the difference calculation process.

[0147] Further, the difference calculation process is a process of calculating a luminance difference with the same color picture element adjacent in the direction of the same color picture element, and the calculation process calculates a standard deviation of the calculated values. It is preferable that

[0148] In the liquid crystal display panel inspection method of the present invention, when the same color picture elements are adjacent to the picked-up image in the direction in which the same color picture elements are arranged, they are separated from the picked-up image by N elements. Further, an extraction process for extracting the value of the imaging element for each N elements in the arrangement direction and dividing it into N element groups is performed, and then the standard deviation of each of the extracted element groups is calculated. Next, a maximum value detection process is performed to obtain the maximum standard deviation force of the N element groups extracted with the same alignment force. Finally, the detected value is directly intersected with the direction of the alignment. The line defect in the direction of the arrangement of the same color picture elements is extracted by executing a comparison process in which the comparison is made in the direction in which the pixels are aligned.

[0149] As described above, the image analysis method according to the present invention is 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. The difference absolute value calculation step for calculating the same color picture element sequence 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 a plurality of the same color picture elements And an average value calculating step for calculating.

[0150] As described above, the image analysis apparatus according to the present invention has the luminance value of the target picture element included in the captured image and the same color picture adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements. A difference absolute value calculation means for calculating an absolute value of a difference value from the luminance value of the elementary element, and an average value of the absolute values of the difference values calculated by the difference absolute value calculation means are arranged in a plurality of arrangement directions of the same color pixels. The average value calculating means for calculating along

[0151] As described above, the image analysis method according to the present invention is a pixel of interest included in the captured image. A difference value calculating step of calculating a difference value between the luminance value of the same color pixel and the luminance value of the same color pixel adjacent to the target pixel in the arrangement direction of the plurality of same color pixels, and calculating in the difference value calculating step And a standard deviation calculating step for calculating the standard deviation of the difference values for each of the imaging element columns arranged in the arrangement direction of the plurality of same-color picture elements.

[0152] As described above, the image analysis apparatus according to the present invention has the luminance value of the target picture element included in the captured image and the same color picture adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements. A difference value calculating means for calculating a difference value with respect to the luminance value of the element, and an image sensor for arranging the standard deviation of the difference value calculated by the difference value calculating means in an arrangement direction of the plurality of same-color picture elements And a standard deviation calculating means for calculating each column.

[0153] As described above, the image analysis method according to the present invention is an interval between the plurality of same-color picture elements in the captured image, and includes an attention portion of the target picture element and a method of arranging the plurality of same-color picture elements. When the interval between the same color pixel adjacent to the target pixel in the direction and the portion corresponding to the target portion is defined as the pixel interval, from the captured image, along the arrangement direction of the plurality of same color pixels. Extracting the luminance value of the image sensor for each pixel interval to form a group of luminance values, and the standard deviation of the luminance values included in the group of luminance values formed in the extracting step A standard deviation calculation step for calculating the luminance value for each group of luminance values, and a maximum value calculation step for calculating the maximum value of the standard deviation calculated in the standard deviation calculation step for each row of the plurality of same-color picture elements. It is the composition which includes.

[0154] As described above, the image analysis apparatus according to the present invention is an interval between the plurality of same-color picture elements in the captured image, and includes an attention portion of the target picture element and a method of arranging the plurality of same-color picture elements. When the interval between the same color pixel adjacent to the target pixel in the direction and the portion corresponding to the target portion is defined as the pixel interval, from the captured image, along the arrangement direction of the plurality of same color pixels. A luminance value of the image sensor for each pixel interval to extract a luminance value group, and a standard deviation of luminance values included in the luminance value group formed by the extraction means. A standard deviation calculating means for calculating the luminance value for each group of luminance values, and a maximum value calculating means for calculating the 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. It is a configuration.

[0155] Therefore, the detection sensitivity is higher than that of the defect detection apparatus to which the conventional defect detection method is applied. There is an effect that the defect of the display panel can be detected.

[0156] The specific embodiments or examples made in the detailed description section of the invention are to clarify the technical contents of the present invention, and are limited to such specific examples. Therefore, the present invention should not be construed in a narrow sense, and can be carried out with modifications within the spirit of the present invention and the scope of the claims described below.

Industrial applicability

[0157] Since defects in display panels, particularly multi-domain liquid crystal panels, can be detected with high detection sensitivity, the present invention can be applied to inspection apparatuses that inspect these display panels.

Claims

The scope of the claims

[1] Detect a defect in the display panel by capturing a display panel in which multiple pixels of the same color are arranged in a certain direction with an imaging device that has an image sensor and analyzing the luminance value of the captured image. An image analysis method in an image analysis apparatus included in an inspection apparatus, the luminance value of a target picture element included in the captured image and the same color picture element adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements A difference absolute value calculating step of calculating an absolute value of a difference value from the luminance value of

An average value calculation step of calculating an average value of the absolute values of the difference values calculated in the difference absolute value calculation step along an arrangement direction of the plurality of same-color picture elements. .

[2] The maximum luminance value calculation step of calculating the maximum value of the luminance values of a plurality of image sensors that have captured the target picture element for each column of the image sensors arranged in the arrangement direction is the difference absolute value calculation step. Including before

In the difference absolute value calculation step, the absolute value of the difference value between the maximum value related to the pixel of interest and the maximum value related to the same color pixel adjacent to the pixel is calculated for each column of the image sensor. The image analysis method according to claim 1, wherein the image analysis method is characterized.

[3] Detecting defects in the display panel by capturing a display panel in which multiple pixels of the same color are arranged in a certain direction with an imaging device that has an image sensor and analyzing the luminance value of the captured image An image analysis method in an image analysis apparatus included in an inspection apparatus, the luminance value of a target picture element included in the captured image and the same color picture element adjacent to the target picture element in the arrangement direction of the plurality of same color picture elements A difference value calculating step for calculating a difference value from the luminance value of

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.

[4] A display panel in which a plurality of pixels of the same color are arranged in a fixed direction is imaged by an imaging device having an image sensor, and the luminance of the obtained captured image is analyzed to detect a defect in the display panel. An image analysis method in an image analysis apparatus included in an inspection apparatus, The interval between the plurality of same-colored pixels in the captured image, and the target portion of the target pixel of the target pixel and the same-color pixel adjacent to the target pixel in the arrangement direction of the plurality of same-color pixels. When the interval between the part corresponding to is the pixel interval,

In the 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 pixels from the captured image, and in the extraction step A standard deviation calculating step of calculating the standard deviation of the luminance values included in the formed luminance value group for each of the luminance value groups;

An image analysis method comprising: a maximum value calculation step of calculating a maximum value of the standard deviation calculated in the standard deviation calculation step for each of the plurality of columns of the same color picture element.

[5] A display panel in which a plurality of pixels of the same color are arranged in a certain direction is imaged by an imaging device having an image sensor, and a defect in the display panel is detected by analyzing the luminance value of the obtained captured image. An image analysis apparatus in an inspection apparatus that performs

Absolute difference that calculates the absolute value of the difference 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 of interest in the arrangement direction of the plurality of pixels of the same color A value calculating means;

An image analysis 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. .

[6] A display panel in which a plurality of pixels of the same color are arranged in a certain direction is imaged by an imaging device having an image sensor, and the luminance value of the obtained captured image is analyzed to detect defects in the display panel. An image analysis apparatus included in the inspection apparatus,

A difference value calculating means for calculating a difference value between a luminance value of the 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;

A standard deviation calculating means for calculating a standard deviation of the difference value calculated by the difference value calculating means for each column of the image pickup elements arranged in an arrangement direction of the plurality of same-color picture elements. Analysis device.

[7] A display panel in which a plurality of pixels of the same color are arranged in a certain direction is imaged by an imaging device having an image sensor, and the luminance of the obtained captured image is analyzed to detect a defect in the display panel. An image analysis apparatus included in the inspection apparatus,

The interval between the plurality of same-colored pixels in the captured image, and the target portion of the target pixel of the target pixel and the same-color pixel adjacent to the target pixel in the arrangement direction of the plurality of same-color pixels. When the interval between the part corresponding to is the pixel interval,

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, an extraction unit that forms a group of luminance values, and the extraction unit A standard deviation calculating means for calculating the standard deviation of the luminance values included in the formed luminance value group for each of the luminance value groups;

An image analyzing apparatus comprising: a maximum value calculating unit that calculates a maximum value of the standard deviation calculated by the standard deviation calculating unit for each of the plurality of columns of the same color picture element.

[8] A display panel in which a plurality of same-color picture elements are arranged in a certain direction is imaged by an imaging device having an image sensor, and the luminance value of the obtained captured image is analyzed to detect defects in the display panel. An inspection device for

The image analysis device 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.

[9] An image analysis program for causing a computer to function as each of the above means of the image analysis device according to any one of claims 5 to 7.

[10] A computer-readable recording medium in which the image analysis program according to claim 9 is recorded.