JPH06294756A - Defect inspection system - Google Patents

Abstract

PURPOSE:To detcet the defects only in an inspection region by providing an run length encoding means for obtaining the address at a varying point of a binary image data, and an intermediate data setting means for setting flags of a starting point and an ending point of defect, and the inspection region and an uninspection region. CONSTITUTION:A line CCD camera 1 reads in the image data of an object C and the image data is binarized. A run length encoding means 5 determines the address at a varying point of the binarized image data. An intermediate data setting means A sets flags for the starting point and ending point of defect, and inspection region and uninspection region based on a data delivered from the encoding means 5. A decision flag for uninspection region is set at the time of starting the inspection. A decision means B performs connective processing based on the intermediate data and set an inspection region decision flag of the intermediate data connected with the uninspection region at the starting time of inspection at the uninspection region. The uninspection region is not operated but the intermediate data is operated only for the inspection region thus detecting a defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting defects such as foreign matter, dirt, scratches, black spots, pinholes and fish eyes contained in image data read by a sensor such as a line CCD camera.

[0002]

2. Description of the Related Art Foreign matter, dirt, scratches, black dots, etc., contained in image data read by a sensor such as a line CCD camera.
Various types of defect inspection devices for inspecting defects such as pinholes and fish eyes have been announced. For example,
There is a high-speed line defect inspection device of a feature extraction system (for example, model name: LSC-100 (manufactured by Mitsubishi Rayon Co., Ltd.), a pattern matching type printed circuit board appearance inspection device, a printed matter defect inspection device, and the like.

[0003]

With regard to the feature extraction method, the defect and the normal portion are discriminated from the value of the image data. However, when detecting defects contained in a plurality of patterns as described above, it is necessary to determine not only the value of the image data but also the position of the image data. For example,
The defect outside the pattern and the defect inside the pattern are the same as the image data, but only the latter needs to be detected as a defect. In the prior art, there is no discrimination function as described above.

On the other hand, with regard to the apparatus of the pattern matching system, it is necessary to once record one repeat of the image in the memory by the matching system of the normal image and the measured image. Therefore, it is preferable to create a large number of patterns of the same pattern, but this cannot be adopted when only one sheet is created and when the pattern creation accuracy is poor. Also,
Currently, has been put to practical use is the case of the image memory of the order of 1000 ² pixels, as in the present invention thousands ^{2 to} several tens of thousand ²
In the case of a very large image such as a pixel, it cannot be practically inspected.

The present invention has been made on the basis of the above background, and an object thereof is to detect a defect while discriminating an inspection region and a non-inspection region, and to include a defect in a plurality of print patterns. It is an object of the present invention to provide a defect inspection apparatus that can be used for a defect inspection performed on a substrate or a defect in a complicated plane shape.

[0006]

The present invention, which is a feature extraction method in the classification of the prior art, solves the problems of the prior art by adding a function of discriminating between an inspection area and a non-inspection area.
That is, the defect inspection apparatus of the present invention is a defect inspection apparatus that reads an image of an inspection object with a line CCD camera and detects a defect included in this image data. Run length coding means for obtaining the change point address of the, the data obtained by the run length coding means, at least the start point, the end point of the defect, and the intermediate data setting means for setting the determination flag of the inspection area and the non-inspection area, Consistency processing is performed on the basis of the intermediate data, and the determination means sets the inspection area determination flag of the intermediate data connected to the non-inspection area at the start of inspection to the non-inspection area, and detects only the defect in the inspection area. It is characterized by doing.

[0007]

The present invention having the above structure operates and acts as follows. In the defect inspection apparatus of the present invention, the line CC
With the D camera, read the image data of the inspection object,
This image data is binarized. The run length encoding means obtains the change point address of the binary image data. The intermediate data setting means sets at least a start point and an end point of the defect and a determination flag for the inspection area and the non-inspection area from the data obtained by the run length encoding means. At this time, when the inspection is started, it is a non-inspection area, and the determination flag of the non-inspection area is set.

Further, the judging means performs the connectivity processing based on the intermediate data, and sets the inspection area discrimination flag of the intermediate data connected to the non-inspection area at the start of the inspection to the non-inspection area. Since the intermediate data is calculated based on this determination flag, the calculation is not performed for the non-inspection area, but the intermediate data is calculated only for the inspection area. As a result, only the defect in the inspection area is detected. According to the present invention, the defect can be detected while discriminating the inspection area and the non-inspection area.

[0009]

EXAMPLES The present invention will be specifically described with reference to examples. FIG. 1 shows a block diagram of an embodiment of the inspection apparatus according to the present invention. In the inspection apparatus of this aspect, the run length encoding means 5 for obtaining the change point address of the binary image data from the signal of the line CCD camera 1, the start point, the end point of the defect from the data obtained by the run length encoding means 5, and Intermediate data setting means A that sets a determination flag for the inspection area and the non-inspection area, performs connectivity processing based on the intermediate data, and sets an inspection area determination flag for the intermediate data that is connected to the non-inspection area at the start of inspection. The determination means B is set in the non-inspection area and detects only defects in the inspection area.

In this apparatus, the image data of the inspection object C is read by the line CCD camera, the image data is binarized, the run length encoding means 5 obtains the change point address of the binary image data, and the intermediate point is obtained. The data setting unit A sets the start point and the end point of the defect and the determination flags of the inspection region and the non-inspection region from the data obtained by the run length encoding unit 5. At the start of the inspection, it is a non-inspection area, and the determination flag of the non-inspection area is set. The determination unit B performs the connectivity processing based on the intermediate data, sets the inspection area determination flag of the intermediate data connected to the non-inspection area at the start of the inspection to the non-inspection area, and calculates the non-inspection area. Is not performed, the intermediate data is calculated only for the inspection area, and only the defect in the inspection area is detected.

FIG. 2 is a diagram showing a device configuration of an embodiment according to the present invention. The line CCD camera 1 has 20 elements.
It is a line CCD camera (model name SCC-2048, manufactured by Mitsubishi Rayon Co., Ltd.) having 48 elements and a clock of 20M.
2 is an image processing device (manufactured by Mitsubishi Rayon Co., Ltd., model name LSC)
-100). An A / D converter 3 performs A / D conversion on the signal from the line CCD camera 1 with 8 bits. Reference numeral 12 is a reference value memory, which is a line CCD camera 1.
Is a memory for recording one line. Reference numeral 11 denotes a threshold value memory, which sets a threshold value for each element of the line CCD camera 1. For example, when a fixed value is designated, the same value is recorded in the threshold memory 11.

Variations between elements of the line CCD camera 1,
When correcting unevenness of illumination, lens distortion, etc., the threshold value is specified as transmittance or reflectance. At this time, image data obtained by reading a subject having uniform transmittance or reflectance is recorded in the reference value memory 12, and the product of this image data and the transmittance or reflectance is stored in the threshold memory 1.
Record at 1. Reference numeral 4 is a comparator, which binarizes the output of the A / D converter 3 according to the logic designation 7 by the value of the threshold memory 11. 5 is a run length encoding circuit, which converts the binary data output from the comparator 4 into
Run length encoding. Reference numeral 6 denotes a memory, which can be used similarly to the main memory of the CPU. 7 is a logical designation,
Set 0 to detect white, and set 1 to detect black. A line designation 8 sets a unit of the number of processing lines of the run length code 5. Reference numeral 9 is a run length buffer, which has a capacity of 128 KB and has two series, which are used alternately.

Since the run length code is 2 bytes / piece, up to 32000 defects can be recorded. 10 is
This is a run length buffer sequence switching designation, and switches the run length buffer 9 used by the run length encoding circuit 5. The series opposite to this is the run-length buffer 9 used in the connectivity processing. 13 is RAM,
Reference numeral 14 is a ROM, and 15 is a CPU. A GPIB interface 16 transfers data such as inspection conditions and inspection results with the host computer 17. The host computer 17 sets inspection conditions for the image processing circuit 2 and displays inspection results.

FIG. 3 is a diagram showing an example of a pattern for explaining the image processing contents of the present invention. 18 is an inspection target, and four 20 patterns are printed. 19
Is the inspection range, and the periphery is the non-inspection area 21.
The defects are those inside the pattern 20, such as 22;
Some of them are around the pattern 20 like 23, and some of them are outside the range of the pattern 20 like 24. Since both the non-inspection area and the defective portion are shown in white, it is necessary to discriminate between the inspection area and the non-inspection area during the connectivity processing.

FIG. 4 is a diagram showing the flow of defect detection.
FIG. 4A shows binary data for two rows. The white part is 1 and the halftone part is 0. 4 (b) is shown in FIG. 4 (a).
Is a run-length code, and indicates the start and end points of two lines.

FIG. 4C shows the defect 1 obtained from FIG. 4B.
It is intermediate data for each piece. Among these, the connectivity processing between two lines is performed at the start point and the end point. Area is the value of (end point-start point),
The area of the defect is the time when the run-length codes are no longer connected when addition is performed during the connectivity processing. The left end is the minimum value among the start points during the connectivity processing, and the right end is the maximum value among the end points during the connectivity processing. The difference between the two when the run length codes are no longer connected is the horizontal ferret diameter. The length is obtained by adding the number of rows of the connectivity processing, and the value at the time when the run length codes are no longer coupled is the vertical Feret diameter.

The inspection area discrimination flag indicates whether the run length code is an inspection area or a non-inspection area. 1 is the inspection area, and 0 is the non-inspection area. At this time, when the inspection is started, it is a non-inspection area, and the determination flag 0 of the non-inspection area is set. Therefore, the inspection area discrimination flag is set to 0 for the intermediate data on the first line and 1 for the intermediate data on the second and subsequent lines. Those connected to the run length code of the inspection area discrimination flag 0 during the connectivity processing are changed to 0 and the operation of the intermediate area data is not performed, and the inspection area discrimination flag 1
Those which are connected to the run length code of 1 perform the operation of the intermediate data. By this processing, it is understood that the inspection area and the non-inspection area can be discriminated by treating them as defects only when the inspection area discrimination flag is 1 at the time when the run length codes are no longer connected.

[0018]

According to the defect inspection apparatus of the present invention, it is possible to detect a defect while discriminating an inspection region and a non-inspection region while using the feature extraction method. For example, a defect included in a plurality of print patterns can be detected. Defects can be detected in the field of inspection or defect inspection within a complicated plane shape.

[Brief description of drawings]

FIG. 1 is a block diagram of a defect inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a defect inspection apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing an example of a pattern for explaining image processing contents of the present invention.

FIG. 4 is a diagram showing a flow of defect detection.

[Explanation of symbols]

 1 ... Line CCD camera 2 ... Image processing circuit 3 ... A / D converter 4 ... Comparator 5 ... Run-length encoding circuit 6 ... Memory 7 ... Logical designation 8 ....・ Number of lines 9 ・ ・ ・ Run length buffer 10 ・ ・ ・ Run length buffer series switching designation 11 ・ ・ ・ Threshold memory 12 ・ ・ ・ Reference value memory 13 ・ ・ ・ RAM 14 ・ ・ ・ ROM 15 ・ ・ ・ CPU 16 ... GPIB 17 ... Host computer 18 ... Inspection object 19 ... Inspection range 20 ... Pattern 21 ... Non-inspection area 22-24 ... Defect

Claims (1)

[Claims] 1. A defect inspection apparatus for reading an image of an object to be inspected by a line CCD camera and detecting defects contained in the image data, wherein a change point address of binary image data is obtained from a signal of the line CCD camera. A run length coding means, an intermediate data setting means for setting at least a start point and an end point of a defect, and a determination flag of an inspection area and a non-inspection area from the data obtained by the run length coding means, based on the intermediate data. Connection processing is performed on the non-inspection area at the start of inspection, and the inspection area determination flag of the intermediate data connected to the non-inspection area is set to the non-inspection area, and only the defect in the inspection area is detected. Characteristic defect inspection equipment.