JPH0968412A - Method and apparatus for inspecting through hole plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly accurate judgment of the degree of unevenness of light transmissivity as caused by abnormality in the dimension of a through hole by presenting the difference between the maximum value and a mean value in variations per standardization data area group generated from a contrast data of an image taken. SOLUTION: Light of a light source 44 passes through a diffusion plate 43 and a through hole of a shadow mask SM and a through hole area SMe to which the light is exposed from an opening 45a is taken by a CCD camera 49. An image data Di obtained is taken as contrast data as density value of an image by an image processor 54 through a camera controller 62. A low frequency portion thereof is removed to generate a standardization data. As the standardization data indicates the unevenness of the light transmissivity caused by abnormality in the dimension of the through hole, the standardization data is scanned for each specified area group to compute the degree of variations of the data for each area and a difference is presented 52 between the maximum value and a mean value computed. Thus, the degree of variations in the data can be recognized with an emphasis thereby enabling highly accurate judgment of the degree of the unevenness of the light transmissivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a through-hole plate in which a large number of through-holes are arranged in a substantially periodic manner, for inspecting unevenness of light transmittance caused by dimensional abnormality of the through-hole. The present invention relates to an inspection method and an inspection apparatus, and particularly to an inspection method and an inspection apparatus for inspecting a through-hole plate such as a shadow mask for a color CRT or a color filter for a liquid crystal display panel.

[0002]

2. Description of the Related Art Generally, a shadow mask is manufactured by forming a large number of through holes in a thin metal plate by a photo-etching method so as to be arranged almost periodically. This shadow mask manufacturing method corresponds to the coating step of applying a resist having etching resistance to the main surface of the metal thin plate to form a resist film on the main surface of the metal thin plate, and the electron beam passage hole of the shadow mask. By irradiating the resist film with light through a pattern plate having a predetermined pattern, a baking step of baking a predetermined pattern on the resist film, and supplying a developing solution to the resist film on which the predetermined pattern has been baked, A developing step of dissolving and removing a predetermined portion of the film to form a resist film in a predetermined pattern and exposing the main surface of the metal thin plate to be etched, and an etching solution for the metal thin plate having the resist film formed in the predetermined pattern Is supplied to etch the exposed main surface of the thin metal plate that is not covered with the resist film, thereby forming a large number of electron beam passage holes. Consisting of an etching step for forming a through hole.

In the above coating process, when the resist is not uniformly applied to the main surface of the metal thin plate and the film thickness of the resist film formed on the main surface is not uniform, or when the resist film of the metal thin plate is etched in the etching process. If the liquid is not uniformly supplied, local dimensional abnormalities occur in a large number of through holes formed in the thin metal plate.

As a method for inspecting the local dimensional abnormality of the through hole, a method for inspecting unevenness of the light transmittance due to the dimensional abnormality such as the shape and the hole diameter of the through hole is adopted. More specifically, as shown in FIG. 11, first, an inspector holds the shadow mask SM by hand,
A light table 202 having a built-in light source (not shown)
It is arranged in front of the translucent inclined table surface 204. Then, the light of the light source is irradiated onto the shadow mask SM through the inclined table surface 204, and the shadow mask SM is visually observed while being swayed as indicated by an arrow in the drawing. At this time, if a dimensional abnormality such as the shape of the through hole or the hole diameter locally occurs in the shadow mask SM, it is recognized by the inspector as unevenness of the light transmittance passing through the through hole, and this unevenness is allowed. Based on past experience, it is determined whether the shadow mask is a good shadow mask or a defective shadow mask. As the unevenness of the light transmittance caused by the dimensional abnormality of the through holes, the unevenness of the light and shade of the light (unevenness of the light transmittance) is scattered over the entire surface of the shadow mask SM, and the unevenness of the light and shade is partially scattered. There is partial unevenness, streak unevenness in which light and shade unevenness occurs in the vertical or horizontal direction.

[0005]

However, the above-mentioned inspection has the following problems due to the visual judgment of the inspector.

In addition to the above-mentioned unevenness of light transmittance, the inspector
You will also see the amount of light that has passed through the through holes. Further, in the inspection, it is not always necessary to compare the unevenness occurring in the non-defective shadow mask SM, which is a limit sample, with the unevenness occurring in the shadow mask SM to be inspected. Of the shadow mask SM to be inspected
It was done while visually observing only the unevenness. Therefore, a high level of skill and considerable experience are required to determine the quality by comparing the unevenness of the limit sample and the shadow mask SM to be inspected. Even if the level of skill and experience are almost the same, the quality judgment may vary due to individual differences among the inspectors and the health condition.

Further, when the light amount distribution is substantially uniform over the entire area of the through hole in the shadow mask SM where the through hole is formed, there is the following problem in determining the quality of unevenness. It is indispensable to prepare the limit sample that is the basis of the judgment in order to judge the contrast with the limit sample.
There is a limit to the preparation of the limit sample. This is because the manner of occurrence of unevenness is not uniform because it is affected by the quality in each of the above-mentioned steps and the composition of the metal thin plate as a raw material. Therefore, due to the limitation of the limit sample, in the case where the shadow mask SM having a substantially uniform light amount distribution and good unevenness has a slight unevenness in light and shade, the above-described overall unevenness is a good shadow mask SM. In the simple contrast determination of, the shadow mask SM may be a good product. However, such a shadow mask SM may be a defective product in a high-quality cathode-ray tube, and in some cases it may not be sufficient to simply make a visual inspection by an inspector to make a comparison with a non-defective product.

The present invention has been made to solve the above problems, and improves the reliability in determining the quality of unevenness in the light transmittance caused by the dimensional abnormality of the through holes of a through hole plate such as a shadow mask. With the goal.

[0009]

Means for Solving the Problems and Their Actions / Effects In order to solve such problems, the inspection method for a through-hole plate according to the first aspect of the present invention relates to a through-hole plate in which a large number of through-holes are arranged almost periodically. In the inspection method of a through-hole plate for inspecting unevenness of light transmittance caused by dimensional abnormality of the through-hole, the through-hole plate is irradiated with light from one main surface side of the through-hole plate to the other side. Image pickup step of obtaining the gradation data of the picked-up image by removing the low-frequency component appearing in the distribution of the individual data belonging to the gradation data, and the normalized data from the gradation data. A low-frequency removing step for generating a standardized data for each predetermined area group, and a dispersion calculating step for calculating the degree of dispersion of individual data belonging to the area group for each area group; Maximum degree of variation obtained for each group And it calculates an average value, having a presentation step of presenting the difference between the maximum value and the average value the calculation.

In order to solve the above-mentioned problems, the inspection device for a through hole plate according to the second aspect of the present invention is based on a through hole size abnormality in a through hole plate in which a large number of through holes are arranged almost periodically. In the inspection device of the through-hole plate for inspecting the unevenness of the light transmittance that occurs, an irradiation unit that supports the through-hole plate and irradiates the supported through-hole plate with light from one main surface side thereof, Imaging means for imaging the light-transmitted aperture plate from the other main surface side to obtain gradation data of the captured image, and low frequency components appearing in the distribution of individual data belonging to the gradation data. And a low-frequency removing unit that generates standardized data from the gradation data, and the standardized data is scanned for each predetermined area group, and the degree of variation of individual data belonging to the area group is determined by the area. Variation calculation means for calculating each group, and obtained for each area group It calculates the maximum value of the degree of serial variation and the mean value, having a presenting means for presenting the difference between the maximum value and the average value the calculation.

In the inspection method for a through-hole plate according to the first invention or the inspection device for a through-hole plate according to the second invention, which has the above-mentioned structure, light is emitted from one main surface of the through-hole plate to transmit the light. To pass through. Thereby, light is transmitted through the through holes of the through hole plate, and a light-dark distribution is obtained on the other main surface side of the through hole plate according to the density of the arrangement of the through holes. This distribution of brightness and darkness is captured as gradation data, which is the density value of a pixel, through the imaging of the through-hole plate.

Then, the gradation data is subjected to the removal of the low frequency component, and the low frequency component appearing in the distribution of the individual data belonging to this is removed to be standardized data. In this standardized data, by removing the above low frequency components,
The low frequency component data distribution, that is, the gradual distribution of light and dark that follows the density of the arrangement of the through holes of the through plate is removed, and unevenness of the light transmittance caused by the dimensional abnormality of the through holes appears. .
The unevenness of the light transmittance shown in the standardized data is captured for each area group by scanning the predetermined area group of the standardized data, and is reflected in the degree of variation of the data calculated for each area group. That is, the unevenness of the light transmittance shown on the through-hole plate is grasped as the unevenness of each predetermined area group, and is also regarded as the degree of data variation for each area group. Even if the unevenness of the light transmittance is slightly different, the data area is narrowed in the area group, so that the degree of data unevenness is emphasized. On the other hand, the average value of the degree of variation obtained for each region group serves as an index of unevenness of the through-hole plate scanned in this region group. Therefore, by presenting the difference between the maximum value and the average value of the variation degree obtained for each region group, the degree of variation degree of data can be emphasized and recognized, and the degree of unevenness of light transmittance can be accurately determined. It is possible to distinguish well.

In the configuration of the first aspect of the present invention, the determination step of determining whether the unevenness of the through-hole plate to be inspected is good or bad based on the difference between the calculated maximum value and the average value, Instead of the presentation step, or with the presentation step.

Further, in the above-mentioned configuration of the second invention,
The present invention has a judgment means for judging whether the unevenness of the through-hole plate to be inspected is good or bad based on the difference between the calculated maximum value and the average value instead of the presentation means or together with the presentation means.

In the inspection method or inspection apparatus for a through-hole plate having these configurations, it is possible to judge whether the through-hole plate is good or bad based on the difference between the maximum value and the average value of the degree of variation obtained for each region group. The determination can be made in a state in which the degree of variation of data is emphasized and with a difference from the index of unevenness. Therefore, according to the inspection method or the inspection apparatus for a through-hole plate having these configurations, it is possible to accurately detect the unevenness of the light transmittance caused by the dimensional abnormality of the through-hole regardless of the density of the unevenness. Therefore, it is possible to improve the reliability of determining whether the unevenness is good or bad.

In order to solve the above-mentioned problems, the inspection method for a through hole plate according to the third aspect of the present invention is based on an abnormal size of the through hole for the through hole plate in which a large number of through holes are arranged almost periodically. In the inspection method of the through-hole plate for inspecting the unevenness of the light transmittance caused by, the through-hole plate is irradiated with light from the one main surface side thereof, and the through-hole plate is imaged from the other main surface side, An image pickup step of obtaining gradation data of the picked-up image, and a low frequency removal step of removing low frequency components appearing in a distribution of individual data belonging to the gradation data and generating standardized data from the gradation data. , A variation calculation step of scanning the standardized data for each predetermined area group, and calculating the degree of variation of individual data belonging to the area group for each area group, and the variation calculation step for each of the area groups. The maximum value of the degree and the frequency are calculated, and the calculated value is calculated. It has a presentation step of presenting the difference in the degree of variation in the degree and the maximum frequency variation of Daine, the.

In order to solve the above-mentioned problems, the inspection device for a through hole plate according to the fourth aspect of the present invention is a through hole plate in which a large number of through holes are arranged in a substantially periodic manner due to an abnormal size of the through holes. In the inspection device of the through-hole plate for inspecting the unevenness of the light transmittance that occurs, an irradiation unit that supports the through-hole plate and irradiates the supported through-hole plate with light from one main surface side thereof, Imaging means for imaging the light-transmitted aperture plate from the other main surface side to obtain gradation data of the captured image, and low frequency components appearing in the distribution of individual data belonging to the gradation data. And a low-frequency removing unit that generates standardized data from the gradation data, and the standardized data is scanned for each predetermined area group, and the degree of variation of individual data belonging to the area group is determined by the area. Variation calculation means for calculating each group, and obtained for each area group Serial calculates the maximum value and frequency of the degree of variation, having a presenting means for presenting the difference in the degree of variation in the degree and the maximum frequency variation of the maximum value the calculation.

In the inspection method for a through-hole plate according to the third invention or the inspection device for a through-hole plate according to the fourth invention, which has the above-described structure, light is emitted from one main surface of the through-hole plate to transmit the light. To pass through. Thereby, light is transmitted through the through holes of the through hole plate, and a light-dark distribution is obtained on the other main surface side of the through hole plate according to the density of the arrangement of the through holes. This distribution of brightness and darkness is captured as gradation data, which is the density value of a pixel, through the imaging of the through-hole plate.

Then, the gradation data is subjected to the removal of the low frequency component, and the low frequency component appearing in the distribution of the individual data belonging to this is removed to be standardized data. In this standardized data, by removing the above low frequency components,
The low frequency component data distribution, that is, the gradual distribution of light and dark that follows the density of the arrangement of the through holes of the through plate is removed, and unevenness of the light transmittance caused by the dimensional abnormality of the through holes appears. .
The unevenness of the light transmittance shown in the standardized data is captured for each area group by scanning the predetermined area group of the standardized data, and is reflected in the degree of variation of the data calculated for each area group. That is, the unevenness of the light transmittance shown on the through-hole plate is grasped as the unevenness of each predetermined area group, and is also regarded as the degree of data variation for each area group. Even if the unevenness of the light transmittance is slightly different, the data area is narrowed in the area group, so that the degree of data unevenness is emphasized. On the other hand, since the degree of variation in the maximum frequency of the degree of variation obtained for each area group is obtained for a large number of area groups, it is used as an index of the unevenness of the through-hole plate scanned in this area group. Become. Therefore, by presenting the difference between the degree of variation of the maximum value of the degree of variation obtained for each region group and the degree of variation of the maximum frequency, it is possible to emphasize and recognize the degree of variation of the data. It is possible to accurately determine the degree of unevenness in the transmittance.

In the configuration of the third aspect of the invention, the quality of the unevenness of the through-hole plate to be inspected is determined based on the difference between the calculated degree of variation of the maximum value and the degree of variation of the maximum frequency. It has a discriminating step of replacing the presenting step or together with the presenting step.

Further, in the configuration of the above-mentioned fourth invention,
A discriminating means for discriminating the quality of the unevenness of the through-hole plate to be inspected based on the difference between the degree of variation of the calculated maximum value and the degree of variation of the maximum frequency,
Instead of the presenting means or together with the presenting means.

In the inspection method or inspection apparatus for a through-hole plate having these configurations, the through-hole plate is detected based on the difference between the degree of variation in the maximum value of the degree of variation obtained for each region group and the degree of variation in the maximum frequency. Since the quality of the unevenness is determined, this determination can be made in a state in which the degree of the variation of the data is emphasized and with a difference from the index of the unevenness. Therefore, according to the inspection method or the inspection apparatus for a through-hole plate having these configurations, it is possible to accurately detect the unevenness of the light transmittance caused by the dimensional abnormality of the through-hole regardless of the density of the unevenness. Therefore, it is possible to improve the reliability of determining whether the unevenness is good or bad.

[0023]

Other Embodiments of the Invention The above-mentioned invention can also adopt the following other embodiments. According to a first aspect, in the above invention, low-frequency components appearing in a distribution of individual data belonging to the grayscale data are removed, and standardization data is generated from the grayscale data by using the grayscale data. smoothing is performed by a median filter having a filter window of m rows and n columns (m and n are natural numbers) to obtain smoothed data,
The gradation data is divided by the smoothed data to generate the standardized data.

In the first mode, the low-frequency components appearing in the distribution of individual data belonging to the gradation data are effectively removed by the smoothing by the median filter, and the low-frequency components are removed and smoothed. Data. After the gradation data is divided by this smoothed data, the low-frequency component data distribution and the gentle distribution of light and dark that follows the density of the arrangement of the through holes in the through-hole plate are removed, and the normalized data is transparent. It represents the unevenness of the light transmittance caused by the dimensional abnormality of the holes. Therefore, according to the first aspect as well, it is possible to accurately detect the unevenness of the light transmittance caused by the dimensional abnormality of the through hole regardless of the density of the unevenness, and the reliability of the determination of the goodness of the unevenness is high. Can be increased.

According to a second aspect of the present invention, in the configuration of the above-mentioned second and fourth inventions, the calculating means scans the standardized data for each area group in a partial range of the area. It has a means for making the groups overlap.

According to the inspection apparatus of the second aspect, when the standardized data is scanned so that the area groups do not overlap with each other, unevenness in the light transmittance exists across the area groups before and after the area data. However, the unevenness can be accurately detected, and the reliability of the quality determination of the unevenness can be further improved.

Further, in a third aspect based on the configurations of the second and fourth inventions, the arithmetic means determines the size of the area group when the standardized data is scanned as the unevenness. It has area group setting means for setting according to the type.

According to the inspection apparatus of the third aspect, regardless of the type of unevenness of light transmittance, the unevenness is included in the region group so that the degree of the variation of the data is effectively emphasized. You can For example, in the case where the unevenness of the light transmittance is scattered over almost the entire surface of the through-hole plate or the partial unevenness is partially scattered, a square size (a row × a Columns; a is a natural number) or rectangular size (b rows × c columns; b and c are natural numbers) region groups. Further, in the case of vertical unevenness in which the unevenness of the light transmittance occurs in the vertical direction, a rectangular size with the side along the direction of occurrence of the unevenness as the long side (d row × e column; d, e is Natural number d <e)
In the area group, the vertical unevenness can be effectively included at the location where the vertical unevenness occurs. Further, in the case of lateral unevenness in which unevenness of the light transmittance is generated in a stripe pattern in the lateral direction, a rectangular size having the long side on the side in which the unevenness occurs (f row × g column; f, g
Is a group of regions of natural number f> g), and lateral unevenness can be effectively included at the location where the lateral unevenness occurs. Therefore, according to the inspection device for a through-hole plate having these configurations, it is possible to detect unevenness with high accuracy regardless of the type of unevenness, and it is possible to further enhance the reliability in determining whether the unevenness is good or bad.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described based on an embodiment of a shadow mask inspection apparatus. First, the external structure of the shadow mask inspection apparatus 30 of this embodiment will be described. As shown in the front view of FIG. 1, a shadow mask inspection device 30 includes an optical measuring device 40 for capturing an image of a shadow mask SM and obtaining image data, and a data processing device 50 for performing various data processing based on the image data. It is composed of.

The optical measuring device 40 is provided with a surface plate 41, and an opening for allowing illumination light to pass therethrough is formed at the center of the upper surface of the surface plate 41. A diffusion plate 43 (for example, a glass plate or a plastic plate) that diffuses and transmits light is placed on the upper surface of the surface plate 41.
A light source 44 is disposed below the light source 3. This light source 4
As 4, a high-frequency lighting fluorescent lamp is used, for example. A mask plate 45 is placed on the upper surface of the diffusion plate 43, and the shadow mask SM is attached and fixed to the mask plate 45 with an adhesive tape or the like.

A stand support arm 46 extending upward is erected from the surface plate 41, and the stand support arm 4 is provided.
6, a camera holding beam 47 is provided so-called cantilever. Further, since the camera holding beam 47 is attached to the stand supporting arm 46 so as to be adjustable by an adjustment mechanism (not shown), the camera holding beam 47 and the CCD.
The camera 49 and the camera 49 can be moved together in the vertical direction (Z direction in the drawing). Further, the CCD camera 49 is adjustably attached to the camera holding beam 47, and the CCD camera 49 can be moved in the left-right direction (X direction in the drawing). Therefore, the CCD camera 49 can be moved vertically and horizontally so that the areas to be imaged by the shadow masks of various sizes and the imaging area of the CCD camera 49 coincide with each other.

The CCD camera 49 is a CCD camera in which CCD elements are two-dimensionally arranged, and is capable of digitally outputting 10 bits of light and shade of an image in a light and shade range. Note that CC
An image of 1,534 pixels × 1,024 pixels can be acquired from the D camera 49.

The data processing device 50 comprises a display 52 for displaying an image to be described later, an image processing device 54 for performing various image processings, and a camera control device 62 for controlling the gain and shutter speed of the CCD camera 49. There is.

Next, the electrical configuration of the shadow mask inspection apparatus 30 will be described with reference to the block diagram of FIG. The light emitted from the light source 44 sequentially passes through the diffusion plate 43 and the through hole of the shadow mask SM and enters the CCD camera 49. At this time, the shadow mask SM is brought into close contact with and fixed to the mask plate 45, and the through hole region SMe, which is a region where the through hole of the shadow mask SM is formed, is the opening 45 of the mask plate 45.
The peripheral region of the shadow mask SM exposed from a and having no through hole is masked. Therefore, the CCD camera 49 images the shadow mask SM with respect to the through hole area SMe, and the two-dimensionally arranged grayscale image (multivalued image).
Image data Di. This image data Di is
After being captured by the image processing device 54 via the camera control device 62 and subjected to image processing described later, various images are displayed on the display 52.

The image processing device 54 is a general-purpose high-speed image processing device that performs various processes according to a pre-registered program, and a CPU 66 that performs various other image processes and other predetermined processes, and an image. Main storage device 68 such as RAM for temporarily storing data such as data Di
A keyboard 70 for inputting data, an auxiliary storage device 72 for storing data such as image data Di, such as a flexible disk device, and a printer 74 for issuing inspection results and the like. They are connected to each other via a bus line 64. In addition, the camera control device 62 is connected to the bus line 64 of the image processing device 54.
And the display 52 are connected.

Next, the unevenness inspection process performed by the shadow mask inspection apparatus 30 of this embodiment will be described with reference to the flowcharts of FIG.

The flow chart of FIG. 3 shows an outline of the unevenness inspection processing of the shadow mask SM performed in this embodiment. When the processing is started, initialization necessary for performing the subsequent processing is performed. (Step S100). For example, the inspection start initial screen is displayed on the display 52, and the memory area used in the process described later is cleared.

When this initialization is performed, the display 52
An initial setting screen is displayed on the screen, and the input locations of various items (initial setting items) required in the process of the subsequent inspection processing remain uninput on the initial setting screen.

Subsequent to step S100, various items required in the inspection process are initialized (step S110). In this initial setting, data is sequentially input to the initial setting items on the initial setting screen that is displayed with no data input in the initialization process. That is, as shown in the flowchart of FIG. 4 showing the detailed processing of the initialization processing, the output file name of the inspection result (step S11
1), the mask type of the mask plate 45 used for masking the shadow mask SM to be inspected (step S11
2), The inspector name (step S113) is sequentially input.
These are posted on the inspection result displayed or printed out after the inspection is completed. The output file is a file for storing the inspection result for each shadow mask SM to be inspected, and the data format thereof is the sample ID (for example, manufacturing serial number) of the shadow mask SM to be inspected and the inspector name. , It is constructed so that the inspection date etc. can be saved.

When these inputs are completed, the process waits until the inspection start switch is pressed (step S114). When the inspection is started, the output file is opened (step S115) to prepare for the output of the inspection result. It should be noted that this output file outputs the determination result for unevenness described later and the data is saved. After that, the initial setting data such as the input output file name is output (step S116), the initial setting data is displayed on the initial setting screen of the display 52, and the result display screen is set (step S117). Then, a result display screen for displaying the result of the quality determination of the unevenness of the shadow mask SM to be inspected is displayed on the display 52 (step S118). The result of the quality determination of the unevenness or the like is automatically input according to the determination result in the unevenness determination processing described later, and the item is the type of the unevenness (total unevenness, partial unevenness, vertical unevenness, horizontal unevenness) or the like. The result is a result of quality judgment for each unevenness.

Subsequent to the above-mentioned initial setting, as shown in FIG. 3, the completion of setting the shadow mask SM by the inspector on the diffusion plate 43 on which the mask plate 45 is placed is waited for, and the switch is operated after the setting is completed. And waits for an input start instruction issued (step S120). If there is an input start instruction, the transmission image of the shadow mask SM to be inspected is taken in and a variety of processes for inspecting unevenness are performed by a series of processes in and after step S122.
First, after step S120, the lighting of the light source 44 is controlled, and the CCD camera 49 is set so as to match the image capturing conditions when capturing the transmission image of the shadow mask SM with the CCD camera 49 (step S12).
2). More specifically, the shutter speed and the gain of the CCD camera 49 are set on the basis of the predetermined imaging conditions such as the shutter speed, the gain and the focus, and the through hole area SMe of the through hole of the shadow mask SM to be inspected. , Focus adjustment and Z of CCD camera 49
Axial position adjustment is performed.

The Z-axis position adjustment is performed by manually operating an adjusting mechanism (not shown) to vertically move the camera holding beam 47 and the CCD camera 49 integrally with respect to the stand supporting arm 46. Settings, gain adjustments, etc. are performed by the camera control device 62. Also,
Focus adjustment is performed by manually adjusting the lens unit 77 of the CCD camera 49. In this case, the focus of the CCD camera 49 is adjusted so as to blur in order to remove moire that occurs between the pixel array of the CCD camera 49 and the periodic arrangement of the through holes of the shadow mask SM.

When the image pickup conditions of the CCD camera 49 are set in this manner, the CCD camera 49 starts image pickup of the shadow mask SM on the diffusion plate 43, and the light emitted from the light source 44 and transmitted through the through holes of the shadow mask SM is transmitted. A transparent image (hereinafter referred to as a raw image) is captured by the CCD camera 49 (step S124). The CCD camera 49 outputs the raw image of the shadow mask SM to the main storage device 68 via the camera control device 62 and the bus line 64 as gradation data with a digital output of 1,534 pixels × 1,024 pixels and a gradation range of 10 bits.

Generally, the intervals between the large numbers of through holes formed in the shadow mask SM are narrow in the central portion of the shadow mask and widen in the peripheral direction. This is because the arrangement of the through holes of the shadow mask SM is designed in consideration of forming the flat shadow mask SM into a dome shape. From this, the shadow mask S
The above-described gradation data, which is the data of the transmission image of M, has a bright and dark pattern (hereinafter, referred to as “dark and bright” in the central portion of the shadow mask SM, which becomes darker in accordance with the density of the arrangement of the through holes of the shadow mask SM. This pattern is referred to as grade) and is the data expressed as a light and shade range.
Moreover, the gradation data also reflects the light and shade based on the unevenness of the shadow mask SM.

Then, the gradation data of this raw image is sent to the image processing device 54 via the camera control device 62. Note that the camera control device 62 displays the raw image on the display 52 along with the data output to the image processing device 54. Thereby, the image pickup area of the CCD camera 49 can be confirmed.

The output signal (gradation data) of the raw image obtained by the CCD camera 49 is superposed with a signal such as uneven light emission distribution caused by the light source 44 or the diffusion plate 43 itself, uneven sensitivity of the image pickup system and the like. . Therefore, the above step S
Following the capture of the raw image in 124, the image data (gradation data) is divided by the reference data (gradation data) having the same number of data to perform shading correction (step S126). The reference data is gradation data of an image previously captured with the shadow mask SM not placed on the diffusion plate 43 and only the mask plate 45 placed, and is stored in the main storage device 68 in advance. Therefore, this reference data is read during shading correction.

Subsequently, a processing target area SMe0 for discriminating streak unevenness in this unevenness inspection processing is set (step S).
128). That is, as shown in FIG. 5, the through-hole region SMe of the through-hole of the shadow mask SM has a curved peripheral edge, and therefore the curved peripheral edge region has a matching number of data when performing the deviation calculation described later. Collapse. Therefore, the rectangular processing target area SM is previously obtained in step S128.
e0 is defined as a plane area defined by the X axis and the Y axis. Next, the set processing target area SMe0
The shading-corrected grayscale data of the above is a median filter (hereinafter abbreviated as M / F) having a filter window of 31 pixels × 31 pixels (hereinafter simply referred to as 31 × 31. The same applies hereinafter). Image correction is performed using (step S130), and low-frequency components are removed from the gradation data by M / F to obtain standardized standardized data.

Here, the contents of the image correction processing in step S130 will be described. In this image correction, the following smoothing process and standardization process are performed. First, in the smoothing process, the data (gradation data) that fills each data window of the 31 × 31 filter window is arranged in the order of size to create a data string, and the data that comes to the center position of the data string is output. The processing that takes a value is one processing unit. Then, for the shading-corrected gradation data for the processing target area SMe0, while changing the M / F filtering area, for example, the filter window is moved pixel by pixel in a predetermined direction to perform the above-described processing in one processing unit. Data area of the gradation data (processing target area SMe0)
Repeat over.

By the smoothing process by the median filter, noise having a high spatial frequency is effectively reduced from the shading-corrected gradation data. Further, smoothed data of an image in which small fluctuations are smoothed can be obtained. The smoothed data reflects the grade and large fluctuations of the shadow mask SM, which is a low-frequency component, but the unevenness of the shadow mask SM is reduced or eliminated as noise or small fluctuations.

In the subsequent normalization process, the shading-corrected gradation data is divided by the smoothed data that has been smoothed in M / F to obtain standardized data for the raw image. In this division operation, when the data value of the smoothed data is zero, the corresponding data is not divided and the corresponding data of the standardized data is set to zero. Since the standardized data thus obtained has undergone division of the gradation data by the smoothed data, the grade and large fluctuation (low frequency component) of the shadow mask SM reflected in the smoothed data as a shade range are removed. , Data representing the unevenness of the light transmittance due to the dimensional abnormality of the through hole.

Since the standardized data represents the unevenness of the light transmittance as described above, it is possible to display the unevenness image on the display 52 based on the standardized data. In this case, the following processing is performed when displaying the uneven image. First, since the standardized data is real number data and is difficult to handle in image processing, it is multiplied by a predetermined integer, for example, 4000 in order to convert it into integer data, to obtain standardized integer data. Next, an image based on this standardized integer data, that is, to display the unevenness of the light transmittance due to the dimensional abnormality of the through hole as an image of the light and shade range data,
Visualization image conversion is performed on the standardized integer data to display the uneven image on the display 52.

Here, the contents of the process from the gradation data to the obtaining of the standardized data will be schematically explained together with the contents of the process for displaying the uneven image. As shown in FIG.
The raw image G captured by the CCD camera 49 is the step S.
After the processes of 124 to 126, the shading-corrected gradation data GD is obtained. The graph in the figure shows the gradation data GD in the image along the horizontal axis of the raw image. On the other hand, the smoothed data M / FD obtained by smoothing the grayscale data GD by the M / F by part of the processing (smoothing processing) in step S130, as shown in FIG. The data is reduced or removed from the gradation data GD as a small variation, and only the grade of the shadow mask SM is reflected.

Then, after the rest of the processing (normalization processing) in step S130, standardized data KD obtained by dividing the gradation data GD by the smoothed data M / FD is obtained. Then, the uneven image is displayed after the integer data conversion of the standardized data KD and the visualization image conversion. As shown in the figure, this uneven image is an image of only the unevenness of the shadow mask SM to be inspected, and since the grade is removed, the unevenness is consequently emphasized.

Subsequent to the above-described image correction, a process for discriminating unevenness in light transmittance is performed (step S140). In this unevenness determination processing, as shown in the flowcharts of FIG. 7 and subsequent figures, determination processing is performed for each type of unevenness (total unevenness, partial unevenness, vertical unevenness, horizontal unevenness). That is, as shown in the flow chart of FIG. 7, first, the discrimination process for the entire unevenness is performed (step S150), and then the discrimination process for the partial unevenness (step S170) and the discrimination process for the vertical unevenness (step S190). The discrimination processing for lateral unevenness (step S210) is sequentially performed. The details of the unevenness discrimination processing are the same, although the detailed processing contents thereof, which will be described later, used for the unevenness differ depending on the unevenness to be discriminated. Therefore, the detailed content will be described below by taking the determination process (step S150) for the overall unevenness as an example.

As shown in the flow chart of FIG. 8, when the discrimination processing for the overall unevenness (step S150) is started, first, the size of the processing window used for data collection in the discrimination processing is selected (step S152).
That is, even in the case of the entire unevenness, the unevenness of the light transmittance is not uniform in the scattered state in the through-hole region SMe of the shadow mask SM or the unevenness in the scattered places. Therefore, the size of the processing window is selected so as to deal with various overall unevenness. Specifically, a small-sized processing window is used for small unevenness, and a large-sized processing window is used for large individual unevenness. In this embodiment, 20 × 20, 30 × 30, 40 × 45,
Processing windows having window sizes of 60 × 60, 80 × 90, and 240 × 180 (units are all pixels) were selected. This is because by selecting such a square or rectangular size processing window, individual unevenness in the overall unevenness can be included in the processing window regardless of its size.

After the window size is set in this way, window scanning and data calculation / storage are performed for the processing window SW of one of the sizes (step S).
154). That is, as shown in FIG. 9, the processing window S
Processing target area S while shifting W by 1/2 pitch
Each time while scanning vertically and horizontally over the Me0 area,
The standard deviation σ of these pieces of grayscale data belonging to the processing window SW is obtained from the following mathematical expression and stored.

[0057]

[Equation 1]

In the above equation, f (x, y) is the density value (gradation data value) at the coordinates (x, y) in the processing window SW, and av is the entire processing target area SMe0 of the shadow mask SM. It is an average density value (grayscale data value), and N is the total number of data in the processing window SW (total number of pixels, 400 if the processing window SW is a 20 × 20 processing window). The value of the average density av is calculated after the processing target area SMe0 is set in step S128 and the image correction is performed in step S130 for the gradation data that has been captured in step S124.
In the present embodiment, the smoothed data M is used for image correction.
Since the gradation data GD is divided by / FD,
The value of the average density av is 1.

As is clear from this equation, the standard deviation σ
Represents the degree of variation of the data belonging to the processing window SW, and if the value of the standard deviation σ is large, the degree of unevenness at the scanning position in the processing window SW is large. The standard deviation σ is calculated and stored each time the processing window SW is scanned until the processing window SW is scanned over the entire processing target area SMe0 as described above.

After that, all the stored standard deviations σ are stored.
Is used to obtain the average value σav, the maximum value σmax, and the most frequent value σpeak (step S156). Average value σ
av is calculated by adding and averaging each time the standard deviation σ is calculated, and the maximum value σmax is the size comparison after each calculation of the standard deviation σ or the size comparison after the calculation of all standard deviations σ. Is required through. In the case of the most frequent value σpeak, the standard deviation σ value and its frequency are plotted every time each standard deviation σ is calculated to create a histogram shown in FIG. The value of the deviation σ is obtained as the most frequent value σpeak.

Then, the absolute value | σmax-σav | of the difference between the maximum value σmax and the average value σav and the maximum value σma.
absolute value of the difference between x and the most frequent value σpeak | σmax-σ
peak | is calculated and these are stored (step S1
58). In this case, the calculated absolute value of these differences | σma
x- [sigma] av | and | [sigma] max- [sigma] peak | are stored in association with the size of the processing window SW and the type of unevenness (total unevenness), and are also displayed on the display 52. Therefore, the inspector determines that the maximum value σ for the standard deviation σ
Absolute value of difference between max and average value σav | σmax−σa
v | and the absolute value | σmax−σpeak | of the difference between the maximum value σmax and the most frequent value σpeak will be presented.

The average value σav of the standard deviation σ for each processing window SW is an index of unevenness in the entire processing target area SMe0 scanned by the processing window SW because it is the average value. Further, since the most frequent value σpeak obtained from the standard deviation σ of each processing window SW is also the value of the standard deviation σ obtained most at various places in the processing target area SMe0, the processing window SW is also the same. It serves as an index of unevenness in the entire scanned processing target area SMe0. On the other hand, the processing window S with a narrow data area
The maximum value σmax of the standard deviation σ obtained for W is such that even if the overall unevenness is a slight unevenness, the data area is narrowed in the processing window SW, so this unevenness is emphasized to some extent. Will be represented. Therefore, the absolute value of the above difference | σmax−σav |,
The inspector who receives the presentation of | σmax-σpeak | can recognize the degree of the overall unevenness as the magnitude of the absolute value of the above difference, so that the unevenness of the light transmittance can be recognized regardless of the shading of the unevenness and the skill of the inspector. The degree can be accurately determined.

Subsequent to the calculation and storage of the absolute values in step S158, these absolute values are stored in the main storage device 68 in advance in the respective discrimination maps (whether the overall unevenness is good or not |
σmax-σav | is associated with the map and whether the overall unevenness is good or bad and | σmax-σpeak | is associated with each other) to determine whether the overall unevenness is good or bad, and the result is stored in the main storage device 68. (Step S160).
In this case, the result of the quality determination of the overall unevenness is the absolute values of the differences | σmax-σav |, | σmax-σpeak |
And the size of the processing window SW and the type of unevenness (total unevenness) are stored.

After that, it is determined whether or not the determination of the overall unevenness is completed for all the processing windows SW selected in step S152 (step S162). If the determination is negative, the processing window SW is changed (step S
164), the process from step S154 is performed by the changed process window SW. On the other hand, step S1
If an affirmative decision is made in 62, the operation proceeds to the next processing, in this case the partial unevenness discrimination processing of FIG. 7 (step S170).

In the partial unevenness discrimination processing in step S170, after the size of the processing window corresponding to various partial unevennesses is selected, the same processing as the above-mentioned determination of the overall unevenness is performed in each selected processing window SW. Perform (steps S154 to 164). The processing window SW selected in this partial unevenness discrimination processing is 10 × 10, 20 × 2.
The processing window has window sizes of 0, 30 × 30, 40 × 40 and 50 × 50. This is because by selecting such a square size processing window, it is possible to include individual unevenness in the partial unevenness in the processing window regardless of its size.

Step S190 following step S170
In the vertical unevenness determination processing in step 1, after selecting the size of the processing window corresponding to various vertical unevennesses, the same processing as the above-described determination of overall unevenness is performed in each of the selected processing windows SW (steps S154-). 164). The processing window SW selected in the vertical unevenness determination processing is a vertically long rectangular size (10
X60, 5x60, 5x90, 10x90 and 15x
This is a processing window having a window size of 90). This is because by selecting such a rectangular processing window, it is possible to include individual unevenness in the vertical unevenness in the processing window regardless of the width and length of the unevenness.

Further, step S190 following step S190
In the lateral unevenness determination processing in 210, after the size of the processing window corresponding to various lateral unevenness is selected, the same processing as the above-described overall unevenness determination is performed in each of the selected processing windows SW (step S154). ~ 164).
The processing window SW selected in this lateral unevenness discrimination processing is
It is a processing window of a horizontally long rectangular size (60 × 10, 60 × 5, 80 × 10, 80 × 5 and 120 × 10) along the horizontal direction which is the direction of occurrence of unevenness. This is because by selecting such a rectangular size processing window, it is possible to include individual unevenness in the lateral unevenness in the processing window regardless of the width and length of the unevenness.

After the pass / fail determination for each unevenness is performed in the processes up to step S210, the process returns to the process of FIG. 3 and the pass / fail determination result in steps S150 to 210 is displayed on the display 52 (step S22).
0). At this time, the type of the processing window SW and the type of the unevenness (the distinction between the whole unevenness, the partial unevenness, the vertical unevenness, and the horizontal unevenness) and the absolute value of the above difference | σmax-σ
av | and | σmax−σpeak | are also displayed on the display 52. After that, another shadow mask S
Whether or not it is necessary to continuously perform the above-described inspection of M is determined from the pressing state of a predetermined switch (step S230). Then, in the case of continuing the inspection, the processing from step S120 described above is repeated. It should be noted that these items in the above determination result are stored in the auxiliary storage device 72 at the time of the corresponding processing together with the sample ID and the like of the corresponding shadow mask SM to be inspected, and regarding other shadow masks SM in step S230. In the case of performing the process of (1), in preparation for the inspection of the other shadow masks SM, the main storage device 68 for erasing the display image of the display 52 and various data temporarily stored in the process of this determination process. Erased from.

As described above, in the shadow mask inspection apparatus 30 of the present embodiment, the respective unevennesses of the whole unevenness, the partial unevenness, the vertical unevenness, and the horizontal unevenness that have occurred in the processing target area SMe0 are processed by the corresponding processing window SW. The standard deviation σ is obtained from the data of density values (gradation data) belonging to the processing window SW each time of scanning. Then, the maximum value σmax, the average value σav, and the most frequent value σpeak are calculated from the standard deviation σ calculated for each scan of the processing window SW, and the absolute values of the differences | σmax−σav |, | σm
Based on ax- [sigma] peak | The maximum value σmax of the standard deviation σ used for this quality judgment is expressed by emphasizing the degree of unevenness by narrowing the area to which the data belongs, and the average value σ of the standard deviation σ.
The av and the most frequent value σpeak are indices of unevenness in the entire processing target region SMe0 through averaging or selection of the most frequent value. Therefore, according to the shadow mask inspection apparatus 30 of the present embodiment, it is possible to accurately detect the various types of unevenness described above even if the density of the unevenness is small in the shadow mask SM to be inspected. It is possible to improve the reliability of the quality judgment of various irregularities (unevenness of light transmittance) caused by the dimensional abnormality of the through holes in the shadow mask SM.

In addition, in the shadow mask inspection apparatus 30 of the present embodiment, the processing window SW is sized so that the corresponding unevenness is effectively included for each of the overall unevenness, the partial unevenness, the vertical unevenness, and the horizontal unevenness. Set. Therefore, it is possible to accurately detect each unevenness regardless of the type of unevenness, and it is possible to further improve the reliability of the quality determination of the unevenness.

Further, in the shadow mask inspection apparatus 30 of the present embodiment, when the processing window SW is scanned over the processing target area SMe0, the processing window SW is shifted by ½ of the pitch and is scanned each time. The standard deviation σ was calculated. Therefore, every time the processing window SW is scanned,
The / 2 window area is in an overlapping state (see FIG. 9). Therefore, regarding the unevenness generated on the periphery of the processing window SW, it is possible to obtain the standard deviation σ by including the unevenness in the processing window SW during the next scanning of the processing window SW. Therefore, according to the shadow mask inspection apparatus 30 of the present embodiment, the unevenness can be detected more accurately regardless of where the unevenness occurs and where the occurrence of the unevenness occurs. Can be further improved.

Further, since the quality judgment result for each unevenness is accurate, the following effects can be obtained. That is, the shadow mask S to be inspected
When M has a defect of unevenness, the result of the unevenness determination is used together with the type of the unevenness and the quality control of each step (coating step, baking step, developing step, etching step, etc.) in the photoetching method of the shadow mask SM. Can be reflected in, and quality can be improved through this.

Further, the shadow mask S to be inspected
In addition to the discrimination result for M, the standard deviation σ obtained in each processing window SW, its maximum value σmax, and the average value σa
v, the most frequent value σpeak and the absolute value of the difference | σma
If x-σav | and | σmax-σpeak | are stored in the auxiliary storage device 72, the following effects can be obtained. Even if the shadow mask SM determined to be non-defective by the unevenness discrimination processing is defective in quality at a later date, if the above data at the time of the discrimination processing is read and displayed, it is stored as the pointed out defective quality. The data can be contrasted. Therefore, it is possible to re-examine the validity of the quality determination and the validity of the map for the quality determination, and to easily investigate the cause of the quality defect by comparing the determination result with the quality defect.

Here, a modification of the shadow mask inspection apparatus 30 of the above embodiment will be described. In the shadow mask inspection device 30 described above, the maximum value σma of the standard deviation σ is
x, the average value σav, and the absolute value of the difference | σmax-σav | and | σmax-σpeak | obtained from the most frequent value σpeak.
Based on and, the quality of the unevenness is determined. However, the absolute values of the above differences | σmax-σav | and | σmax-σpe
It is also possible to adopt a modified example of the configuration in which the quality of the unevenness is determined based on only one of ak |. In addition, a pass / fail judgment is also made for each of the overall unevenness, the partial unevenness, the vertical unevenness, and the horizontal unevenness. However, if the pass / fail determination is determined to be defective due to any unevenness, the processing may be terminated at that point in time, as a modified example. With the configurations of these modified examples, it is possible to reduce the processing time for determining the unevenness when there is a defective unevenness.

It is also possible to use a processing window SW having a size other than the above size, or to use only a processing window SW having an optimum size among the above sizes.

The embodiments of the present invention have been described above.
The present invention is not limited to such embodiments, and it goes without saying that the present invention can be carried out in various modes without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a front view showing an external configuration of a shadow mask inspection apparatus 30 according to an embodiment.

FIG. 2 is a block diagram showing an electrical configuration of the shadow mask inspection apparatus 30 shown in FIG.

FIG. 3 is a flowchart showing the entire inspection process for unevenness of the shadow mask SM performed by the shadow mask inspection device 30.

FIG. 4 is a flowchart showing the detailed contents of initial setting processing in the unevenness inspection processing.

FIG. 5 is an explanatory diagram for explaining processing contents in the unevenness inspection processing shown in FIG. 3.

FIG. 6 is an explanatory diagram for schematically explaining the content of the processing from the gradation data of the raw image to the obtaining of the standardized data together with the processing content for displaying the uneven image.

FIG. 7 is a flowchart showing the contents of step S140 shown in FIG.

FIG. 8 is a flowchart showing the detailed content of overall unevenness determination processing performed in step S150 shown in FIG.

9 is an explanatory diagram for explaining how the processing window SW is scanned in step S154 shown in FIG.

FIG. 10 is an explanatory diagram for explaining a histogram in which the value of standard deviation σ and its frequency are plotted.

FIG. 11 is an explanatory diagram for explaining how a conventional unevenness inspection is performed on the shadow mask SM.

[Explanation of symbols]

 30 ... Shadow mask inspecting device 40 ... Optical measuring device 41 ... Surface plate 43 ... Diffusing plate 44 ... Light source 45 ... Mask plate 45a ... Opening 46 ... Stand supporting arm 47 ... Camera holding beam 49 ... CCD camera 50 ... Data processing device 52 ... Display 52a ... Display area 54 ... Image processing device 62 ... Camera control device 64 ... Bus line 66 ... CPU 68 ... Main storage device 70 ... Keyboard 72 ... Auxiliary storage device 74 ... Printer 77 ... Lens part SM ... Shadow mask SMe0 ... Processing target Area SMe ... Through hole area SW ... Processing window

Claims (8)

[Claims] 1. A method of inspecting a through-hole plate, comprising: a through-hole plate in which a large number of through-holes are arranged approximately periodically; An imaging step of irradiating a perforated plate with light from one main surface side thereof to image the perforated plate from the other main surface side, and obtaining gradation data of the captured image; and an individual step belonging to the gradation data. A low-frequency removing step of removing low-frequency components appearing in the data distribution and generating standardized data from the grayscale data, and scanning the standardized data for each predetermined area group, A variation calculation step of calculating the degree of variation of the data for each area group, and a maximum value and an average value of the degree of variation obtained for each area group, and the calculated maximum value and average value. And a presentation step for presenting the difference between Inspection method of the through-hole plate to be. 2. The method for inspecting a through-hole plate according to claim 1, wherein the quality of the unevenness of the through-hole plate to be inspected is determined based on a difference between the calculated maximum value and the average value. A method of inspecting a through-hole plate, which has a determining step to be performed instead of or in addition to the presenting step. 3. A through-hole plate inspection device for inspecting a light-through hole plate in which a large number of through-holes are arranged in a substantially periodic manner for inspecting unevenness of light transmittance caused by dimensional abnormality of the through holes. Irradiation means for supporting the perforated plate and irradiating the supported perforated plate with light from one main surface side thereof, and imaging the perforated plate irradiated with the light from the other main surface side, An image pickup means for obtaining gradation data of a picked-up image, a low frequency removing means for removing low frequency components appearing in a distribution of individual data belonging to the gradation data, and generating standardized data from the gradation data, A variation calculation unit that scans the standardized data for each predetermined area group and calculates the degree of variation of individual data belonging to the area group, and the degree of variation obtained for each area group. The maximum value and the average value of Inspection device of the through-hole plate, characterized in that it comprises a presentation means for presenting the difference between the value and the average value. 4. The inspection device for a through-hole plate according to claim 3, wherein the quality of the unevenness of the through-hole plate to be inspected is determined based on a difference between the calculated maximum value and the average value. An inspection device for a perforated plate, which has a determining means to be lowered instead of the presenting means or together with the presenting means. 5. A through-hole plate inspection method for inspecting unevenness of light transmittance caused by dimensional abnormality of a through-hole plate, wherein a plurality of through-holes are arranged approximately periodically. An imaging step of irradiating a perforated plate with light from one main surface side thereof to image the perforated plate from the other main surface side, and obtaining gradation data of the captured image; and an individual step belonging to the gradation data. A low-frequency removing step of removing low-frequency components appearing in the data distribution and generating standardized data from the grayscale data, and scanning the standardized data for each predetermined area group, A variation calculation step of calculating the degree of variation of the data for each area group, and a maximum value and frequency of the degree of variation obtained for each area group, and the degree of variation of the calculated maximum value. The difference between the maximum frequency variation and Method of inspecting hole plate, characterized in that it comprises a Shimesuru presenting step. 6. The through-hole plate inspection method according to claim 5, wherein the through-hole plate to be inspected is based on a difference between the degree of variation in the calculated maximum value and the degree of variation in the maximum frequency. The determination step of determining the quality of the unevenness of
A method of inspecting a through-hole plate, which is provided in place of or together with the presenting step. 7. A through-hole plate inspection apparatus for inspecting unevenness of light transmittance caused by dimensional abnormality of a through-hole plate, wherein a plurality of through-holes are arranged approximately periodically. Irradiation means for supporting the perforated plate and irradiating the supported perforated plate with light from one main surface side thereof, and imaging the perforated plate irradiated with the light from the other main surface side, An image pickup means for obtaining gradation data of a picked-up image, a low frequency removal means for removing low frequency components appearing in a distribution of individual data belonging to the gradation data, and generating standardized data from the gradation data, A variation calculation unit that scans the standardized data for each predetermined area group and calculates the degree of variation of individual data belonging to the area group, and the degree of the variation obtained for each area group. Of the maximum value and the frequency, and the calculated maximum Inspection device of the through-hole plate, characterized in that it has a, and presenting means for presenting the difference in the degree of variation in the degree and the maximum frequency variation of. 8. The through-hole plate inspection apparatus according to claim 7, wherein the through-hole plate to be inspected is based on a difference between the degree of variation in the calculated maximum value and the degree of variation in the maximum frequency. The determination means for determining the quality of the unevenness of
An inspection device for a through-hole plate, which is provided in place of or together with the presenting means.