JPH03167407A - Apparatus for inspecting deviation of display pattern - Google Patents

Abstract

PURPOSE:To decrease the number of pattern comparing circuit by judging whether a pattern is located at a normal position or not based on comparison in template matching and the shift position of a detecting region when the matching degree is at the highest degree. CONSTITUTION:As basic data (a) as a reference in comparison inspection, image data which are equal to a pattern to be inspected and have no position deviation are registered in a second image-data memory means C. Image data containing a pattern region to be inspected R are picked up and stored in a first image- data memory means B. At the time of the inspection, an inspecting region (theta) having the same size as the region R is sequentially shifted in a specified retrieving region Q including the region R. At this time, the detected data are read out of the means B in correspondence with the region (q). The matching degree of both detected data and the reference data which are read out of the means C is examined. Whether the pattern is located at the normal position or not is judged with a position judging means E based on the position of the region (q) when the matching degree becomes the highest value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for inspecting misalignment of designs such as product names printed on product wrapping paper.

[Conventional technology]

For example, products such as soap soap are individually wrapped in wrapping paper and multiple pieces are packed in one box, and the product name and other designs are printed on the wrapping paper on the top of each soap. ing. Therefore, due to the shift of the wrapping paper during the above packaging,
If even one soap does not have the above-mentioned design in a predetermined position, it will be easily noticeable and may damage the quality and brand of the product.

[Problem to be solved by the invention]

Therefore, in the past, each soap was visually inspected to see if the pattern was in a predetermined position, but due to the rapid flow of the line, accurate inspection was impossible.

The present invention has been made in order to eliminate the above-mentioned problems, and an object of the present invention is to provide a display symbol displacement inspection device that automates the inspection of display symbol displacement.

[Means for Solving the Problems] As shown in FIG. 1, the display pattern displacement inspection device of the present invention is a device for inspecting the displacement of a design written on a product or a product wrapping paper, and includes: A camera A that captures an image so as to include the pattern to be inspected or a partial area of the pattern; a first image data storage means B that stores image data captured by the camera A''; a second image data storage means C for storing basic data serving as a reference for the symbol or a part of the symbol;
and, a detection area q having the same size as the area R is set as the area R.
When the shift 1 is performed sequentially within the search area Q including
The detection data read out from the second image data storage stage C and the basic data read out from the second image data storage stage C are stored in each image IP. a template matching means D that compares the degree of matching between both data at each time, and a template matching means D that compares the degree of matching between both data; The present invention is characterized by a position determining means E for determining whether the symbol or a part of the symbol is in a normal position.

[Effect]

As basic data serving as a reference for comparative inspection, image data that is the same as the pattern to be inspected or a part of the pattern and that has no positional deviation is stored in the second image data storage means C.
On the other hand, the image data including the pattern to be inspected or a part of the area R of the pattern is captured by the camera A and stored in the first image data storage means B. At the time of inspection, a detection area q having the same size as the above area is set.
are sequentially shifted within a predetermined search area Q including the area R, sequentially read out as detection data from the first image data storage means B corresponding to the detection area q, This detected data and the second image data storage stage C
The template matching means D compares each pixel with the basic data read out from the template matching means D to improve the degree of matching between the two pieces of data. The position determining means E determines whether the symbol or a part of the symbol is in a normal position.

〔Example〕

FIG. 2 shows an embodiment of the display pattern deviation inspection device of the present invention.

! indicates a stone spear to be inspected, which is conveyed by a conveyor 2 to the left in the figure at a constant speed. 3 and 4
Soap in the inspection position! This is a sensor that detects whether or not it has been transported. Reference numeral 5 is a lighting lamp for illuminating the stone Ml at the inspection position, and a high-frequency fluorescent lamp is used to eliminate flickering caused by commercial frequency. 6 is a camera using a CCD image sensor, which captures an image of the upper surface of the soap l at the inspection position.

Reference numeral 7 denotes a CPU (central processing unit) for centrally controlling the present apparatus, which includes an image processing unit 7a that functions during image processing, which will be described in detail later. 8 is CPU7
This is a ROM (read only memory) that stores control programs executed by the ROM. 9 is a signal input port, and the detection signal from the sensor 3.4 is taken into the CPU 7 via this signal input port 9. IO is an image memory that stores the video signal from the camera 6, and 1l is an image monitor display for monitoring the image captured by the camera 6. 12 is a keyboard for inputting various setting conditions and the like. 13 is a soap l for which a defect due to misalignment of the display pattern was detected by the inspection of this device.
It is a discharge device for discharging from the flow of the line,
14 is a signal output section of the CPU 7 to the ejection device 13,! Reference numeral 5 denotes a measurement result display display for displaying the test results performed by this apparatus, and 16 is a floppy disk device for storing the test results as data.

Next, the operation of the apparatus having the above configuration will be explained according to the flowchart of FIG. 3(A).

First, we will discuss the basic patterns required for the inspection described below. FIG. 4 shows an image of the soap l taken by the camera 6, and the outer frame 4l is the imaging area of the camera 6. In Soap 1, "bac" is a trade name, "WH Summer TE" is a product name, and below Soap 1 is a striped pattern.

Pattern to be inspected (hereinafter referred to as inspection pattern R)
may be any of the above-mentioned letters or designs, but in this embodiment, the central letter "a" in "bac" is used. Accordingly, it is necessary to register in advance the basic pattern R0, which is the same as the inspection pattern R, as a reference pattern for comparison, and the information for this basic pattern Rn is shown in FIG. 5(A). Like, the letter ゜a”
It includes pixel data for the area , and data of the distance HXsy of the character "a" from the edge of the soap l, and the method of registering it will be described later.

Now, in step S1, when the type of stone stone 1 to be inspected is selected using the keyboard 12, a desired pattern is read out from the floppy disk drive from among the basic patterns R0 registered for each product M. Next step S2
When the soap l comes to a predetermined inspection position and the predetermined detection signal from the sensor 3.4 is taken into the CPU 7, the soap l imaged by the camera 6 is read in step S3. The image is taken into the image memory IO.

In step S4, it is determined whether or not the soap 1 is being conveyed to the inspection position [ζ one after another. If it is being conveyed continuously, the process proceeds to the next step S5. By the way, one field of screen is captured by the camera 6. It takes 1/60 seconds to capture an image, so if a camera with a shutter is used, the shutter is released at the beginning of the field, so it will take 1/60 seconds to capture the next image. Therefore, in the worst case, there will be a lag of 1/60 seconds between the detection signal from sensor 3.4 and the actual image capture, and the line speed will be 40n/2.
In the case of 1 minute, as shown in FIG. 4, the soap 1 moves 11 times in 1/60 seconds. Therefore, in step S5, one edge L of the soap l is detected from the image data of the soap l stored in the image memory 10, and the separation distance X (the 5 (B)), and the separation distance Y (shown in FIG. 5 (C)) of the soap l in the direction orthogonal to the line flow direction. The position of the image data of the soap 1 is corrected based on the distance measured in the same manner. In step S6,
As shown in FIG. 5(D), a search area Q centered on the letter "a", which is the test pattern R, is determined.

In the next step S7, as shown in FIG. 5(E), the area of small sections (
Template matching is performed to check the degree of matching between the image data read from the detection area q (hereinafter referred to as detection data) and the image data of the basic pattern R0 (hereinafter referred to as basic data). This template matching process will be specifically explained using pattern diagrams shown in FIGS. 6 to 8.

Figure 1-1-1-9 in Figure 6 shows the first stage of template matching, and in Figure I-1, 1-1-1-9 shows the first stage of template matching.
The 2x12 pixel area is the search area Q shown in Figure 5(D).
The white or black dots in the 3x3 pixel area R surrounded by a circle indicate the inspection pattern R to be inspected. Expressed, this test pattern R has the following pixel information.

The detection area q is a detection area q, and the extent to which the detection data from this detection area q matches the basic data from the basic pattern R0 is investigated, but in order to make the matching judgment explained below easier to understand. , the basic pattern R is in the detection area q.

pixel information is shown.

In Figure I-1, the detection data read from the detection area q is subtracted between each corresponding pixel in order to examine it, resulting in the following table.

As you can see in the table above, the subtraction result is 0, and by counting the number of pixels, you can find the number of matching pixels.
In pattern 1-1, the number of matching pixels is four.

When the matching determination in Figure 1-1 is completed, the detection area q is shifted to the right by four pixels, as shown in Figure 1-2. The detection data in this I-2 diagram is the same as last time, all “
0'', the number of matching pixels is four.

When the detection area q reaches the right end as shown in the following figure 1-3, the detection area q returns to the left end and shifts downward by one or four pixels as shown in the next figure 1-4.

At the next 1-5rlJ, the detection area q and the inspection pattern R come to match in some pixels. The detected data at this time is as follows, and when subtracted from the basic data, the number of matching pixels that becomes O is 6, and the patterns I-t to I-
The degree of matching is higher than in case 4.

Since the number of matching pixels in each of the following figures 1-6 to I-9 is four, in the first stage matching, the degree of matching is highest in the comparison in figure 1-5. Therefore, as shown in Fig. 1-10, an area Q' which is centered around the detection area q in Fig. I-5 and expanded by two pixels around it is set as the search area in the second stage shown in Fig. 7.

I[-1 In the diagram, the detection area q starts from the upper left within the search area Q° and is now shifted by two pixels.

In this case, as in the first stage, when we examine the number of matching pixels, we find n-1, n-4, II-7, and 4 in Figure 1-9.
II-2, If-3, n-5 and I
In Figure I-6, there are six, indicating a high degree of matching. In this example, in order to simplify the explanation, the image data was set to 144 pixels of 12Xl2, and the reference image data was set to 9 pixels of 3x3, so the above n-2, II-
3, II-5 and n-6, the matching degree is the same, but the search area Q actually applied is 3600 pixels of 60×60, and the detection area q is 784 pixels of 28×2B.
Since it is a painting industry, the degree of matching is the highest in any one of the matching methods. Here, we will proceed with the following discussion assuming that the degree of matching is highest in the n-2 diagram.

As shown in Figure II-10, a search area Q'' is set as an area centered around the detection area q in Figure II-6 and expanded by one pixel around it, and then the third stage shown in Figure 8 is performed. Proceed to.

In the third stage, the detection area q is shifted one pixel at a time from the upper left within the search area Q''.As is clear from the figure, the degree of matching in this case is as shown in Figure III-9 between the detection data and the basic data. reaches its maximum value at the end of t, where t completely matches, and the number of matching pixels becomes 9.Therefore, in the next step S8, as shown in Figure III-10, [[-9
The position of the detection area q in the figure is detected, and the detected position is set as the position of the character @a", which was the inspection pattern R of the soap l, and the distance 111x, y (th) between that position and the basic pattern R0 is determined. 5 (A) shown), the amount of deviation of the displayed pattern on the soap l to be inspected is calculated.In step S9, it is determined whether the product is good or defective based on the size of the amount of deviation, and the amount of deviation is If the value is larger than the specified value and the product is determined to be defective, the process proceeds to step SIO for discharge processing.

FIG. 3(B) is a subroutine showing the discharge process in step SIO. First, in step S21+trowel, the soap l is removed from the line by the discharge device l3, and in the next step S22, such a discharge operation is performed. It is determined whether or not the discharge operation is continuous, and if the discharge operation occurs sporadically, the process advances to step S25, and a display indicating that the discharge operation has been performed is displayed on the measurement result display 15. On the other hand, if the discharge operation continues, it is assumed that there is a problem with the production line, and the process proceeds from step S22 to step S23, the production line is stopped, and an abnormality is displayed in the next step S24.

Returning to FIG. 3(A), in the next step Sll, the measurement results such as the amount of deviation are displayed on the display l5, and when the end key is pressed on the keyboard 12 in the next step S12, this detection The mode ends and the original step S
Return to l, but if not, return to step S2,
Next, the same test as described above is performed on the soap l delivered to the test position.

In this way, during the inspection process, stones a flowing through the line are
The positional deviation of the displayed pattern is inspected in real time with respect to t, and the amount of deviation is displayed on the measurement result display l5. By checking the amount of deviation, you can determine whether the product is good or defective. Thereby, the inspection pattern R for the soap 1 determined to be good can be registered in the floppy disk device 16 as the basic pattern R0.

In the template matching described above, the comparison operation is divided into three stages, and an appropriate search area Q. Q',Q
”, the total number of comparisons that need to be made for one stone can be reduced.For example, if the search area Q
is 60 x 60 pixels and the detection area q is 28 x 28 pixels, the detection area q is set for pattern comparison within the search area Q.
The range of movement is 32 ÷ 4 = 8 movements because in the first step, every 4 pixels are compared, which means 9 movements including the comparison at the origin, 9 times in the horizontal direction and 9 times in the vertical direction. A total of 81 basic patterns are compared.

In the second stage, the comparison with the basic pattern is performed nine times for every two pixels, centering on the location where the match was the best in the first stage.

In the third stage, each pixel is compared nine times with the basic pattern, centering on the location where the match was the best in the second stage.

Therefore, the total number of comparisons is 9X9+9+9=99 times.

On the other hand, this is normal! When using the pixel-by-pixel template matching method, 60-28=32 Comparative movement of 32 pixels in the horizontal direction and 32 pixels in the vertical direction is required, and if the comparison of the origin is included, 33 comparisons are required, and 33X33= That's 1089 times.

In this way, the template matching method applied to the present invention can reduce the number of comparisons to about one-eleventh of the usual number and enable high-speed inspection.
Even in a line where a large quantity of 300 to 300 pieces flows, the inspection device can be implemented using an inexpensive computer device.

〔Effect of the invention〕

As explained above, the present invention enables detection data read out by sequentially shifting a predetermined readout area with respect to image data for a product to be inspected, and basic data registered in advance with no positional deviation. By checking the degree of matching using the template matching method, we can detect the position of the design or part of the design of the product and determine whether it is good or bad. It is possible to detect the positional shift of the displayed pattern. Also, when comparing patterns in template matching, the detection area q is shifted not by one pixel but by several pixels to detect the approximate position of the pattern or part of the pattern to be detected, and then If we narrow the search area to Q゜ centered on Q゜ and then use a method to perform similar pattern comparisons, the number of pattern comparisons can be greatly reduced.
Therefore, the present device can be implemented using an inexpensive computer device with a slow processing speed.

[Brief explanation of the drawing]

Fig. 1 is a complaint correspondence diagram of the display pattern deviation inspection device of the present invention, Fig. 2 is a system diagram showing an embodiment of the present invention, and Fig. 3 (A) and Fig. 3 (B) are Fig. 2 4 is a flowchart showing the control operation of the illustrated device; FIG. 4 is a diagram showing an image of the stone spear captured by the camera 4 in the device shown in FIG. 2;
FIG. 5(A) is a diagram showing the basic pattern for the stone clam shown in FIG. 4, FIG. 5(B) and FIG. Figure 5 (D) is
FIG. 5(E) is a diagram showing the search area set for the inspection pattern for soap. FIG. 5(E) is a diagram showing template matching. FIG. 6 to 8 are pattern diagrams showing comparison processing performed in template matching. ! ...Soap, 2...Conveyor, 3.4...Sensor 5...Lighting light, 6...Camera, 7...CPU,
7a... Image processing section, 8... ROM, lO... Image memory 11... Image monitor display, l2... Keyboard, l3... Ejection device, l5... Measurement result display display, l6...Floppy disk device.

Claims (2)

[Claims] (1) A device for inspecting the positional deviation of a design written on a product or product wrapping paper, which includes a region R of the design or a part of the design to be inspected.
a first image data storage means that stores the image data taken by the camera; and a second image data storage means that stores basic data serving as a reference for the pattern or a part of the pattern without positional deviation. image data storage means, and a detection area q having the same size as the area R.
, the detection data read out from the first image data storage means and the basic information read out from the second image data storage means corresponding to the detection area q. a template matching means that compares the data pixel by pixel to check the degree of matching between the two data; 1. A display symbol shift inspection device comprising: position determination means for determining whether the symbol or a part of the symbol is in a normal position. (2) The template matching means detects the detection area q
By shifting by m pixels, a second search area Q'(<Q) centered at the position of the detection area q when the matching degree is the highest is set, and this second search area Q' 2. The display pattern shift inspection device according to claim 1, wherein the operation of shifting the detection area q by n (<m) pixels is repeated until the amount of shift of the detection area q becomes 1 pixel.