JPS61114103A - Pattern positioning method of image processing - Google Patents

Abstract

PURPOSE:To increase the accuracy of data for position shift detection by adding statistical processing of smoothing to position shift processing and optimizing the quantity of a shift. CONSTITUTION:Nine-bit squares 9 and 10 are extracted from the entire planes of images 7 and 8 at the same positions and data 11 at the center point of one square 9 is ORed exclusively with all data of the other square 10. Data of the square 10 which have the same value with the data 11 at the center position of the square 9 are given a value 1 through said logical operation and an integral counter 13 counts up by one. This logical operation is carried out (512-9)X(512-9) times for the entire planes of the images 7 and 8 to extract 9-bit squares while the squares are shifted by one bit longitudinally and laterally, so that the value of the integral counter is graphed as shown in 14. Data of the graph 14 are smoothed to obtain a graph 17 and there is only one counter having a minimum value, so that accurate position shift detection is performed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to alignment, which is pre-processing, in image processing in a printed circuit board pattern inspection device, and in particular, to a suitable method for comparing identical patterns. Regarding pattern alignment.

[Background of the invention]

In conventional pattern position deviation detection, when calculating the amount of deviation,
It was calculated based on the amount of deviation between the center point of one pattern and the other pattern. This method uses a plurality of integration counters to find and calculate the minimum value of the counter values. This has the disadvantage that the amount of deviation cannot be calculated if there are multiple minimum values. An example of a patent that describes pattern alignment in detail is Japanese Patent No. 57-113227.

[Purpose of the invention]

An object of the present invention is to provide a method for accurately detecting positional deviations of a pattern by performing statistical processing in consideration of the periphery of a pixel, rather than detecting positional deviations on a pixel-by-pixel basis.

[Summary of the invention]

The present invention attempts to accurately calculate the positional deviation by adding a statistical method to the problem, since the validity of the positional deviation could not be verified when the positional deviation was detected in pattern alignment. It is.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 shows an example of the configuration of an apparatus for inspecting patterns on printed circuit boards. This device compares two identical printed circuit boards,
It detects defects. Camera 1.2 is a detector that takes 5.12w square images from two printed circuit boards. Stage 3.4 has the same width in the same direction (= 5
m) is a drive system that moves together. The printed circuit board 5.6 is placed and fixed on the stages 3 and 4.

The defect detection method of this device is to detect defects from two identical printed circuit boards.
Patterns at the same coordinates are extracted, the image is binarized, and pattern matching is also performed.

The range that can be detected at one time is 5. I2w square pattern7.
8, so the stage 3.4'a: is moved by 5 pitches, and the detection pattern section 7.8'! Defects are detected over the entire plane of the printed circuit board by shifting f-1.

FIG. 2 shows a circuit for detecting the positional deviation of the extracted portion 7.8 from the binarized pattern extracted by the camera 1.2. This circuit is necessary to correct deviations in images to be compared and to perform accurate comparison. Positional deviation calculation is performed only in a range of 7.8 of the extracted image. The method is to extract 9 points 9° and 10 from the same location on all planes of image 7.8, and from the extracted 9 and 10, data 11 of the center point of one 9 and data 11 of the other 10. Performs an exclusive OR operation with all data. In this calculation, data 10 having the same value as data 11 at the center position of 9 becomes 1, and 1 is added to the integrated value 13. This operation is 7
．． 9-bit square extraction for all image planes of 8,
Shifted by 1 bit vertically and horizontally (512-9)
When the process is repeated 2-9) times, the value of the integration counter is represented as a graph of 14. As a result, the amount of positional deviation can be calculated from the counter number having the smallest value.

However, there may be some inconvenience in the calculation.

That is when multiple counters have the minimum value.

Therefore, as a solution to this problem, smoothing as shown in FIG. 3 is performed. Smoothing is a method of adding data around one point to obtain the value of that point, as shown in Figure 4.
This takes into account surrounding data. Therefore, if the data represented by graph 14 is smoothed, graph 17 will be obtained, and only one counter will have the minimum value, allowing accurate positional deviation detection.

〔Effect of the invention〕

According to the present invention, by adding statistical smoothing processing to positional deviation detection, the amount of deviation can be optimized, which increases the accuracy of positional deviation detection data.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a pattern and a detection method in a printed circuit board pattern inspection device, Fig. 2 is a diagram showing the configuration of a pattern position deviation detection circuit, Fig. 3 is a diagram showing the smoothing results after pattern position deviation detection, and Fig. 4 is a diagram showing a pattern position deviation detection circuit configuration diagram. The figure is a diagram showing an example of a smoothing method. 1.2... Camera, 3, 4... Drive stage, 5,
6... Printed circuit board, 7.8... Detection pattern section,
9゜10...Binarization position shift detection comparison/Turn,
1]... Reference pixel for positional deviation detection, 12... Positional deviation width, 13... Integration counter for positional deviation detection, 14.
・Graph of counter value of integrated color group, 15,1.
6... Array of integration counters, 17... Graph of smoothing of integration counters, 18... Example of data before smoothing, 1
9...Example of data after smoothing.

Claims (1)

[Claims] 1. In a printed circuit board pattern inspection system that simultaneously photographs the details of two printed circuit boards that should have the same pattern using two cameras and compares them to detect defects, In order to compare patterns of the same part and extract the same part, a two-step process is performed in the positional deviation amount calculation method that accurately calculates the amount of positional deviation in order to perform alignment correction before detecting defects. In the first stage, from the binarized data of the pattern, the point at the center of one side of the pattern (pixel data) and all the points on the other side (pixel data) are subjected to an exclusive OR operation, and then integrated. A pattern alignment method in image processing characterized in that the amount of deviation is calculated by adding smoothing of the integrated value to the second stage of calculating the amount of deviation from the minimum value of the values.