JP2002049910A - Method and device for testing nonuniformity of periodic pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately test area deviation that partially takes place in a pattern in testing the area deviation of a periodic pattern on the basis of an area image. SOLUTION: An image means obtained by arranging a pixel string in a cross direction picks up an image of a test object having a periodic pattern in which a pattern of a prescribed width is repeated in a cross direction and inputs a pattern image, an area is measured in each block in which a pixel string (line) is made as a unit in regard to each pattern on the inputted pattern image, the measured area of each block is respectively converted into a luminance value, each converted luminance value is respectively set in a unit pixel in which a pixel is made as a unit, the area image is prepared by arranging unit pixels in which each luminance value is respectively set while associating with the sequence of each block, and area deviation and its nonconformity are tested on the basis of the prepared area image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a periodic pattern, and more particularly, to a method in which a light transmitting pattern is periodically formed on a substrate such as an aperture grill used for a cathode ray tube of a color television and a color filter used for a liquid crystal display. The present invention relates to a method and an apparatus for inspecting a periodic pattern, which are suitable for detecting a deviation in the area of a pattern and unevenness of the pattern in a product formed in a suitable manner.

[0002]

2. Description of the Related Art Industrial products having a periodic pattern in which a minute pattern as a unit is repeated include a shadow mask used for a cathode ray tube of a color television and a color filter used for a liquid crystal display.
In an industrial product having such a periodic pattern, each pattern has a predetermined shape and area (size) based on a design value, and a pattern existing around the pattern has a shape corresponding to each adjacent pattern. They are arranged repeatedly with a predetermined interval between them.

[0003] The area (size) of such an individual pattern is always (1) always the same regardless of the location on the entire surface (entire) of the sample, or (2) gradually increases depending on the location in the sample. (For example, the area is increased from the center toward the periphery).

[0004] When such an industrial product is manufactured, it is necessary to perform the following inspection for deviation (area deviation) of the area of each pattern from the design value. (1) If even one pattern has an area deviation exceeding the limit level, it is determined as a defect. (2) In the evaluation of each pattern, even if the area deviation can be regarded as normal within the limit level, it is determined as a defect if the area deviation occurs locally in a plurality of patterns within a certain range. In the latter case, the detection of local occurrence is not limited to the individual patterns within the limit level. Means inspecting the non-uniformity (unevenness) of the area.

[0005] Inspection of the deviation and non-uniformity of the area between the patterns as described above includes (1) a visual inspection in which an inspector directly inspects an inspection object (industrial product) by visual inspection and (2) )
A partial automatic inspection in which several representative regions are determined for an inspection object, the regions are input as an image using an imaging device, and only the patterns included in the representative regions are measured and inspected by image processing for an area. ) The entire surface of the inspection object (whole)
There is a full-automatic inspection in which an image is input and all patterns are individually measured and inspected.

[0006]

However, the visual inspection described in the above (1) has individual differences among inspectors and is easy to be overlooked, and the inspection time in the (2) partial automatic inspection is short. Although there is an advantage, since the inspection is performed only in the representative area, a defect generated in a pattern in the other area cannot be inspected. In addition, in the full-surface automatic inspection of (3), the inspection time is very long because the entire surface is inspected, and the type of the inspection object whose area gradually changes depending on the place (region) in the sample is required. Since the area between each pattern and the limit level of the deviation are different for each area, an inspection by the inspector is required for the measured area data, but when the number of patterns is increased, this inspection is performed. There is a problem that even if you try to do.

[0007] Further, as a common problem in the automatic inspection, it is not possible to detect the uneven defect in which an area shift within a limit level is locally concentrated in each pattern.

In order to solve the above-mentioned conventional problems, the present applicant can easily inspect the defect of the area generated in each pattern for the entire inspection object, and furthermore, the deviation within an allowable range is localized. Japanese Patent Application No. 2000-149332 has already proposed a technique for inspecting a periodic pattern that can easily inspect an unevenness defect having an area which is concentrated on a pattern. Hereinafter, this is referred to as a proposed invention.

In the proposed invention, in a method for inspecting a periodic pattern, an image of an inspection object having a periodic pattern is captured, a pattern image is input, and an area of each pattern on the input pattern image is measured. The measured area of each pattern is converted into a luminance value, each converted luminance value is set as a unit pixel having a fixed number of pixels as a unit, and the unit pixel in which each luminance value is set is, Area images are created by arranging them in association with the order of each pattern, and area deviations and unevenness are inspected based on the created area images, so that area deviation defects and unevenness defects occurring in the pattern can be reliably detected. Inspection is possible.

Hereinafter, the proposed invention will be described in detail with reference to specific examples. FIG. 1 is a schematic perspective view, including a block diagram, showing a main part of an example of an inspection apparatus according to the proposed invention.

The inspection apparatus includes a stage 10 on which an inspection object W is mounted, a CCD camera (imaging means) 12 which is disposed above the stage 10 and which images the object W and inputs an inspection image. An X-axis guide 1 for guiding the camera 12 in the X direction when the camera 12 is moved by a driving unit (not shown).
4, a Y-axis guide 16 for guiding in the Y-direction together with the guide 14, and the camera 12 guided by these guides 14 and 16 to scan the inspection object W in the XY directions indicated by the arrows. When capturing the object W, the camera 1
An image input unit 20 including a camera controller 18 for controlling the camera 2 and an image processing unit 2 for processing an inspection image captured and input by the CCD camera 12
2, the image processing unit 22 and the camera controller 18
And a device control unit 24 for controlling the entire device.

As shown in FIG. 2, the inspection apparatus is roughly divided into an inspection processing unit 26, a human interface unit 28, and a machine interface unit 30.
And the entire operation of each functional unit included in each of these units 26 to 30 is controlled by the device control unit 24. The inspection processing unit 26 includes the image input unit 20 as a functional unit and the image processing unit 22 that processes image data input by the image input unit 20. Similarly, the human interface unit 28 An information display unit 32 for displaying the results processed by the processing unit 22 and a personal operation unit 34 for exchanging information with an operator are provided by a machine interface unit 30.
Is a machine interlocking unit 36 that exchanges information with an external machine such as a belt conveyor (not shown) that conveys an object.
Each of these function units 26 to 30 is managed by the device control unit 24 as a whole.

Each of these functional units will be described in detail. An apparatus control unit 24 for managing the operation of each of the above functional units 26 to 30
For example, a dedicated device, a general-purpose sequencer, a personal computer, or the like can be used. Further, as the CCD camera 12 included in the image input unit 20, an area sensor camera or a line sensor camera can be used, and as an imaging means, an imaging tube or the like can be used.

As the image processing section 22, a dedicated image processing device, a personal computer, or the like can be used. or,
The information display unit 32 displays the inspection progress status for the operator,
It has the function of presenting inspection results, counting results, history of past inspection results, etc., and displaying captured images, images in the course of processing, or images after processing, such as CRT monitors, liquid crystal monitors, and LED arrays. Etc. are available.

The interpersonal operation unit 34 (1) accepts an input operation required for the inspection from the operator, (2) sets the characteristics (size, etc.) of the inspection object, and (3) the image processing unit 22 Set adjustment values (filter size, etc.), (4)
It has a function of setting an adjustment value (shutter speed or the like) of the image input unit 20, and can use a mechanical button, a touch panel, a keyboard, a mouse, and the like.

The machine interlocking unit 36 synchronizes with an external device at the time of the automatic inspection, for example, synchronizes the supply of the inspection object to the image input unit 20 with the end timing, and instructs the distribution apparatus to be inspected based on the inspection result. Instructions for sorting and sorting the inspection target,
It has a function of issuing a request to stop the supply to the inspection unit, etc., including RS-232C, RS-422, GPIB (General
Purpose Interface Bus), LAN (Ethernet), parallel I / O, relay, etc. can be used.

In the proposed inspection apparatus, the image processing unit 22 has an inspection object W having a periodic pattern.
Means for measuring (calculating) the area of each pattern on the pattern image obtained by capturing the image by the CCD camera 12 and means for converting the measured area of each pattern into a luminance value Means for setting each converted luminance value to a unit pixel having a fixed number of pixels as a unit, and arranging each unit pixel to which each luminance value is set in association with the arrangement order of each pattern Means for creating an area image by using the software and means for inspecting an area deviation based on the created area image are respectively constructed by software.

Next, the operation of the inspection apparatus will be described with reference to the flowchart shown in FIG.

First, as shown in FIG. 1, the inspection object W having a periodic pattern on the stage 10 is scanned by the CCD camera 12 to image the entire object W to form a pattern image. Input (step 1). When a shadow mask is used as the object W, an aperture pattern is imaged as a transmitted light image using a back surface illumination (not shown) provided in the stage 10.

Next, the area of each pattern on the input pattern image is measured (step 2). Here, the area is measured for each pattern. Specifically, the area can be measured by the following image processing.

That is, the input pattern image is binarized by using a threshold value experimentally obtained in advance in accordance with the sample, and the pixels constituting each pattern are turned on in the binary image.
Is converted to be a pixel. As described above, the ON pixels of the binarized image are subjected to the labeling processing, the number of pixels constituting the same labeled individual pattern is obtained, and the obtained number is defined as the area.

After the measurement of the area for each pattern in the pattern image is completed in step 2 above, an area image is created (step 3). FIG. 4 shows the relationship between the pattern image and the area image as an image. FIG. 2A is a pattern image obtained by imaging the inspection object W, and FIG. 2B is a corresponding area image.

As shown schematically in the enlarged upper left corner of the pattern image of FIG. 4A in FIG. 4C, the area of each pattern is given by the numbers (1) to (7). If the value is a brightness value, the corresponding brightness value of the area image is represented by the same number for convenience, as shown in FIG. That is, one area obtained for each pattern in FIG. 4C is set as the luminance value of one pixel (unit pixel), and an area image is created by arranging in the same order as each pattern in the pattern image. The luminance value in this case is 256
In addition to the gradation, that is, 8 bits, it may be displayed in 16 bits depending on the precision, or may be handled in floating point.

When the area image created in the above step 3 is displayed on the monitor of the information display section 32, not only defects of individual patterns but also stripes when the area deviation has directionality are locally concentrated. In this case, since the image appears uneven, it can be visually confirmed on the monitor.

In this embodiment, in order to automatically inspect the area deviation, a specific example will be described later with reference to an example. However, an emphasized image is created from the area image corresponding to FIG. 4D (step 4). The emphasized image is binarized with a threshold value experimentally set in advance to create an area deviation determination image (step 5).

In the emphasizing process in step 4, a spatial filter according to the shape of the defect (unevenness) to be detected is used. If the defect is a vertical stripe, the luminance value of each pixel is processed using a spatial filter as shown in FIG.
Each element constituting this filter corresponds to a pixel, and the numeral is a coefficient by which the luminance value of each corresponding pixel is multiplied. Specifically, the luminance value of each pixel when the center element of the filter is matched with the pixel of interest is multiplied by each coefficient of the corresponding element, and the sum is added to the pixel value of the pixel of interest located at the center. The process of resetting is executed for the entire area image in units of A pixels in the vertical direction. The size A in the vertical direction and the number B of 0 in the horizontal direction are experimentally determined in advance in accordance with the defect to be detected, and are appropriately set.

FIG. 5B shows a spatial filter for enhancing the horizontal streak. The filter for enhancing the vertical stripe shown in FIG.
° Rotated configuration. Although illustration is omitted,
A spatial filter for spot enhancement is also used to extract spot-like unevenness having no directionality in the area deviation. this is,
It is necessary to prepare an appropriate configuration according to the shape of the unevenness, but as an example, a configuration combining the filters of FIGS. 5A and 5B can be used.

As described above, by creating the area deviation determination image in step 5, the automatic inspection can be performed based on whether or not the target binarized pixel exists in the determination image.

Hereinafter, the proposed invention will be described more specifically. FIG. 6 is an example of a pattern image having a size of 4 vertical patterns and 10 horizontal patterns corresponding to FIG. 4C and having no defect. The numbers also shown at the top of this figure indicate the area of each pattern indicated by the corresponding →, and the area (unit: [μm ² ], for example) of each pattern is increased by 2 from left to right and by 1 from top to bottom. Formed in the same design, not entirely shown, but between 10,000 and 1005
It is assumed that it is formed up to 0.

FIG. 7A shows the pattern images having no defect shown in FIG. 6 when the areas between adjacent patterns are measured by image processing and arranged in order. A monochrome area image in which the area based on the actual measurement in FIG. 7A is converted into an 8-bit luminance value is created. FIG. 7B corresponds to this area image, and the figure shows the brightness values set for each pixel corresponding to each area for convenience. The luminance value set for each pixel in FIG. 7B is: luminance = (area-10000) × 5
Is calculated by the conversion formula

The emphasis processing of step 4 is performed on the area image of FIG. 7B. In this example, for the sake of convenience, the filter shown in FIG. 5A is processed by a filter having a configuration of [−1, 2, −1] corresponding to A = 1 and B = 0.
A case in which a vertical stripe-enhanced image shown in (C) is created is shown. In this figure, the positions of the crosses at the left end and the right end represent invalid areas where filter processing cannot be calculated. Here, the filter processing is applied to the area image of FIG. 7B. However, when it is not necessary to visually check the image or when it is desired to eliminate an error due to 8-bit conversion, the area of FIG. Filtering can be applied to the data itself.

When the vertical stripe-enhanced image is created as described above, the image is binarized at a predetermined threshold value as in step 5 to create a judgment image shown in FIG. . In this judgment image, since there is no defect, the pixel value is only 0 which means no defect.

On the other hand, FIG. 8 is a pattern image in the case where there is a deviation (defect) in the area. In the case of FIG. 6 where there is no defect, the area is located in the central pattern portion where the area is arranged in the order of 1008 → 10010. Deviation occurs, 10010 → 10
It has the same value as 010.

When image data corresponding to FIGS. 7A to 7D is created for the pattern image having a defect, the image data becomes as shown in FIGS. 9A to 9D, respectively. In this case, as shown in FIG. 3C, a vertical stripe-enhanced image in which pixel values are enhanced in the positive and negative directions at the center of the pattern is created. As shown in (D), a pixel row having a pixel value of 1 meaning that there is a defect at the center of the pattern is extracted, and a vertical stripe-shaped area deviation defect can be automatically detected.

Although a description based on a specific example is omitted, the case of a horizontal streak-like area shift and the case of a local spread unevenness can be automatically detected in the same manner.

As described in detail above, according to the specific example of the proposed invention, an area image which is a grayscale image representing the area data of each pattern over the entire surface of the sample (test object) is created.
By displaying this on a monitor, a visual inspection of the area deviation becomes possible.

When an automatic inspection for an area deviation is performed by applying a spatial filter to the created area image, a streak-shaped area deviation defect extending in a vertical direction or a horizontal direction is not limited.
Since the deviation of the area within the allowable level can be regarded as unevenness of shading in the area image, for example, a secondary image as proposed by the present applicant in JP-A-6-229736 has been applied to the area image. By applying the "algorithm for inspecting the unevenness of the opening area in the periodic pattern" using a differential spatial filter, it is possible to automatically inspect the locally generated area unevenness. Thus, even when the area unevenness is automatically inspected, the inspector can verify the area data by simultaneously visually inspecting the area image on the monitor.

According to the invention proposed by the present applicant described in detail above, for the entire inspection object having a periodic pattern, it is possible to easily inspect for a deviation in the area of each pattern, and also within the allowable range. An excellent effect is obtained in that unevenness defects in the area where the deviation occurs locally can be easily inspected.

However, as a result of a more detailed study by the present inventors, the proposed invention in which an area is measured for each pattern to create an area image includes a pattern having a predetermined width in the width direction such as an aperture grille. In the case of the inspection object formed repeatedly, it became clear that there was another problem.

That is, in the aperture grille, a pattern composed of narrow strip-shaped slits (openings) is repeatedly formed in the width direction. FIG. 10A shows an image of a pattern image (input image) input by imaging such an aperture grill under reflected illumination. In this figure, the pattern is represented as an elongated black area. Have been. When applying the proposed invention to an aperture grille that can obtain such a pattern image, since the area is measured in units of each pattern, the area of each measured pattern is, from left to right, area a to area j, the corresponding area image is, as shown in the image in FIG. 10 (B), a 1 × horizontal arrangement of luminance a to luminance j obtained by converting these areas into luminance in the width direction, that is, the horizontal direction. It is obtained as an image of the pixel row 1 composed of 10 pixels.

As described above, when inspecting the unevenness of the area of the pattern based on the area image using the pattern as a unit, FIG.
As shown in FIG. 1, if the deviation of the area extends over the entire length of the pattern, the inspection can be performed if it is easy to understand. However, as shown in the third pattern from the right in FIG. In the case where the deviation of the convex part is the same as the deviation of the concave part in the lower part, since it is offset by the entire area of this pattern, the deviation of the area occurring in a part of the pattern You will not be able to inspect.

The present invention has been made to solve the above-described new problem, and is created by converting the area of a periodic pattern in which a pattern of a predetermined width is repeatedly formed in the width direction into luminance. An object of the present invention is to provide a method and an apparatus for inspecting unevenness of a periodic pattern, which can accurately inspect even an area deviation occurring partially in a pattern when inspecting an area deviation of the pattern based on an area image. And

[0043]

According to the present invention, in a method for inspecting unevenness of a periodic pattern, an inspection object having a periodic pattern in which a pattern of a predetermined width is repeated in a width direction is formed by a pixel array in the width direction. A pattern image is input by imaging with the imaging means that matches the pattern, and the area of each pattern on the input pattern image is measured for each block in units of one or more fixed pixel columns. The area of each block is converted into a luminance value, and each converted luminance value is set to a unit pixel having a certain number of pixels as a unit,
The unit pixels for which the respective brightness values are respectively set are arranged in association with the order of the respective blocks to create an area image, and by inspecting the area deviation and the unevenness based on the created area image, It is a solution to the problem.

According to the present invention, in a periodic pattern unevenness inspection apparatus, an inspection object having a periodic pattern in which a pattern of a predetermined width is repeated in a width direction is imaged by aligning a pixel column in the width direction. Imaging means for inputting a pattern image by inputting a pattern image; means for measuring an area of each pattern on the input pattern image for each block in units of one or more fixed pixel rows; Means for converting the area to each brightness value, means for setting each converted brightness value to a unit pixel using a fixed number of pixels as a unit, and a unit pixel for which each brightness value is set,
By providing means for creating an area image by arranging them in association with the order of the blocks and means for inspecting an area deviation and its unevenness based on the created area image, the above-mentioned problem is also solved. It was done.

That is, in the present invention, the pattern is cut into blocks in units of one or more pixel columns, and the area of the blocks is converted into luminance to create an area image. Even in a pattern having a long direction, an area image in which the area of the block unit is reflected over the entire length is obtained, so that the entire area deviation of each pattern can be accurately inspected.

[0046]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The periodic pattern unevenness inspection apparatus according to the present embodiment has substantially the same basic hardware configuration as that of the proposed invention shown in FIGS. 1 and 2, and a description thereof will be omitted. .

The inspection object according to the present embodiment is the same as that shown in FIG.
This is an aperture grille in which a strip-like elongated pattern of a predetermined width, which can obtain a pattern image similar to that shown in FIG. 0 (A), is repeatedly formed in the width direction.

In the inspection apparatus according to the present embodiment, a CCD camera (imaging means) 12 is attached to an inspection object (aperture grill) W placed at a predetermined position on the inspection stage 10 shown in FIG. Along with arranging the pixel row so that the width direction of the pattern formed on the object W coincides with the pixel row,
By imaging the entire pattern of the object W while scanning the CCD camera 12 in the direction of the arrow with the camera controller 18, it is possible to input a pattern image in which pixel rows are orthogonal to the length direction of the pattern. ing. The CCD camera 12 may be an area sensor camera or a line sensor camera.

In this inspection device, the image processing device 22
A means for measuring an area of each block in units of one or more fixed pixel columns for each pattern on the pattern image input as described above, and a luminance value for each block. Means for converting each of the converted luminance values into unit pixels each having a fixed pixel as a unit, and associating the unit pixels with each of the luminance values set with the order of the blocks. Means for arranging and creating an area image, and means for inspecting an area deviation and its unevenness based on the created area image are respectively constructed by software.

The means for measuring the area binarizes the input pattern image with a predetermined threshold value for each of the predetermined pixel rows, based on the number of pixels corresponding to each block after binarization. To measure the area of each block. The inspection means has a function of enhancing the area image by a spatial filter to create an enhanced image, and automatically inspecting the area image based on the enhanced image.

Next, the operation of the present embodiment will be described. Note that the basic processing flow in the present embodiment is substantially the same as the flowchart shown in FIG.

A pattern image is input by imaging the inspection object W having the defect shown in FIG. 12 with the pixel rows aligned in the width direction of the strip pattern as described above. FIG. 13A shows an image of this pattern image (input image). In the figure, a range delimited by a horizontal broken line represents a pixel row, although exaggerated. That is, FIG. 13A corresponds to an image in which an image of a pixel row is superimposed on the pattern image of FIG.

When a pattern image is input as described above, each pattern on the input pattern image is
The area is measured for each block having one pixel column as a unit. FIG. 13B shows a divided image obtained by dividing the pattern image shown in FIG. 13A in units of pixel columns. In FIG. 13B, up to the sixth line is shown for convenience. The area corresponding to the pattern corresponding portion on each divided image divided for each pixel column (line) is measured as a block.

FIG. 14 shows a processing procedure for measuring the area for each block. FIG. 13A is the same as FIG.
Is a divided image of the first line of
It is converted to a value to create a one-line binary image shown in FIG. At the same time, labeling is performed for each pixel included in each block (black area in the figure) to indicate that the pixel is included in the same block. In this labeling, each block is numbered from 1 to 10. Next, the number of pixels labeled with the same number is counted, and is obtained as areas a1 to j1 of each block as shown in FIG.

The processing shown in the image of FIG.
Execute for all pixel columns (lines) after the line,
For convenience, the area of each block is measured as shown in FIG. 15 up to the third line.

Next, the area of each block measured as described above is converted into a luminance value, and each converted luminance value is set to one pixel (unit pixel), and each luminance value is set. By arranging the unit pixels in association with the order of the blocks, an area image as shown in FIG. 15B is created.

Thereafter, based on the created area image, an area deviation and its unevenness are inspected. As this inspection method,
The created area image may be displayed on a monitor screen and visually checked, or the image may be enhanced by a spatial filter to create an enhanced image, and an automatic inspection may be performed based on the enhanced image. The processes such as the measurement of the area, the conversion of the area to the luminance value, the creation of the area image, and the inspection based on the area image are substantially the same as those in the case of the proposed invention, so that detailed description is omitted. .

As described in detail above, according to the present embodiment,
When an area image is created, pixels having a luminance value of the area of each block when the slit (pattern) is divided for each line are arranged and arranged in the order of each block. It is possible to accurately inspect a large change in the area and a deviation or unevenness of the area existing in a part of the slit. Similarly, it is possible to specify the position of the deviation or unevenness of the area occurring in the pattern.

As described above, the present invention has been specifically described. However, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, the method for measuring the area of a block is not limited to the case described in the above embodiment, and a known image processing algorithm for measuring the area from a gray image with high accuracy may be used. A commercially available device that can measure the area from the gray image with sub-pixel accuracy may be used.

In the above embodiment, the pattern image is
Although the case of dividing by one pixel column has been described, a block may be cut out in units of two or more pixel columns. Furthermore,
Although the case where the unit pixel forming the area image is one pixel is shown, there is no particular limitation as long as a certain number is used as a unit.
One area may be converted using a plurality of pixels as a unit.

The inspection object is not limited to the aperture grill, but may be a pattern having a certain length, for example, a color filter.

[0064]

As described above, according to the present invention,
When inspecting the area deviation of the pattern based on the area image created by converting the area of the periodic pattern in which the pattern of the predetermined width is repeatedly formed in the width direction into the luminance, the pattern partially occurs in the pattern. It is also possible to accurately inspect the area deviation.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view, including a block diagram, showing a main part of an inspection apparatus according to a proposed invention.

FIG. 2 is a block diagram showing an outline of an entire inspection apparatus according to the proposed invention;

FIG. 3 is a flowchart showing the operation of the inspection device.

FIG. 4 is an explanatory diagram showing an image of a relationship between a pattern image and an area image.

FIG. 5 is an explanatory diagram showing an example of each spatial filter for vertical stripe enhancement and horizontal stripe enhancement.

FIG. 6 is an explanatory diagram showing an example of an image of a pattern image when there is no defect;

FIG. 7 is an explanatory diagram showing each processed image obtained based on the pattern image of FIG. 6;

FIG. 8 is an explanatory diagram showing an example of an image of a pattern image when there is a defect;

FIG. 9 is an explanatory diagram showing each processed image obtained based on the pattern image of FIG. 8;

FIG. 10 is an explanatory diagram showing an input image when an aperture grill is to be inspected and a corresponding area image;

FIG. 11 is an explanatory diagram showing an example of an area shift occurring in a pattern of an aperture grille.

FIG. 12 is an explanatory diagram showing another example of the area shift occurring in the aperture grill pattern.

FIG. 13 is an explanatory diagram showing a relationship between an input image of an aperture grille and a divided image in units of pixel columns.

FIG. 14 is an explanatory diagram showing a procedure for measuring the area of each block in a divided image.

FIG. 15 is an explanatory diagram showing the relationship between the area of each block and the luminance value of the area image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Stage 12 ... CCD camera 14 ... X-axis guide 16 ... Y-axis guide 18 ... Camera controller 20 ... Image input part 22 ... Image processing part 24 ... Device control part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiko Soeda 1-1-1, Ichigaya-Kaga-cho, Shinjuku-ku, Tokyo Within Dai Nippon Printing Co., Ltd. No.1-1 Dai Nippon Printing Co., Ltd. F-term (reference) 2G051 AA73 AA90 AB20 CA03 CA04 CD04 EA11 EA20 EC05 ED07 ED14 FA10 5B057 AA01 BA02 CE03 CE06 CE12 DA03 DC04 DC22

Claims (6)

[Claims] An image of an inspection object having a periodic pattern in which a pattern of a predetermined width is repeated in a width direction is captured by an imaging unit in which pixel rows are aligned in the width direction, and a pattern image is input. For each pattern on the pattern image, the area is measured for each block in units of one or more fixed pixel columns, and the measured area of each block is converted into a luminance value. Is set as a unit pixel having a fixed number of pixels as a unit, and the unit pixels having the respective set luminance values are arranged in association with the order of the blocks to form an area image. A method for inspecting unevenness of a periodic pattern, comprising inspecting an area deviation and its unevenness based on an image. 2. A method for measuring the area of each block, comprising: determining an input pattern image by a predetermined threshold value for each of the predetermined pixel rows;
The method for inspecting unevenness of a periodic pattern according to claim 1, wherein the method is performed based on the number of pixels corresponding to each block after binarization. 3. The periodic pattern unevenness inspection method according to claim 1, wherein the area image is enhanced by a spatial filter to create an enhanced image, and inspection is performed based on the enhanced image. 4. An image pickup means for picking up an image of an inspection object having a periodic pattern in which a pattern of a predetermined width is repeated in the width direction by aligning pixel rows in the width direction and inputting a pattern image. Means for measuring the area of each pattern in units of one or more fixed pixel rows for each pattern on the pattern image, and means for converting the measured area of each block into a luminance value. Means for setting each luminance value to a unit pixel in units of a fixed number of pixels, and creating an area image by arranging the unit pixels each having the respective luminance value set in correspondence with the order of each block. And a means for inspecting an area deviation and its irregularity based on the created area image. 5. The apparatus according to claim 1, wherein the means for measuring the area binarizes the input pattern image with a predetermined threshold value for each of the predetermined pixel columns, based on the number of pixels corresponding to each block after binarization. The unevenness inspection apparatus for a periodic pattern according to claim 4, wherein the apparatus has a function of measuring the area of each block. 6. The inspection means has a function of creating an enhanced image by enhancing the area image with a spatial filter and performing an automatic inspection based on the enhanced image. 5. The unevenness inspection apparatus for periodic patterns according to 4.