JPH0663734B2 - Deviation inspection device for display pattern - Google Patents

Description

The present invention relates to an apparatus for inspecting a positional deviation of a design such as a product name printed on a wrapping paper of a product flowing in a line.

[Conventional technology]

For example, products such as soap are individually wrapped in wrapping paper and then packed in a plurality of boxes, and patterns such as product names are printed on the wrapping paper that is the upper surface of each soap. There is. Therefore, due to the deviation of the wrapping paper during the above packaging,
If there is at least one soap in which the design is not located at a predetermined position, it is likely to be conspicuous and the quality or brand of the product may be impaired.

[Problems to be Solved by the Invention]

Therefore, conventionally, each soap was inspected by visual inspection for whether or not the pattern was at a predetermined position, but since the flow of the line was fast, it was impossible to perform an accurate inspection.

The present invention has been made to eliminate the above-mentioned problems, and an object of the present invention is to provide a display pattern deviation inspection device in which the inspection of the position deviation of the display symbol is automated.

[Means for Solving the Problems]

As shown in FIG. 1, the display pattern deviation inspection apparatus of the present invention is an apparatus for inspecting a positional deviation of a product conveyed on a line or a pattern printed on the packaging paper of the product, and conveyed to an inspection position. The pattern of the produced product or a part of the pattern is used as an inspection pattern R, and an area 41 including the inspection pattern R
(A) for imaging the image, and image data D of the imaging region 41 imaged by the camera (A)
By comparing the first image data storage means (B) for storing the image data, the image data D stored in the first image data storage means (B), and the image data of the product accurately set at the inspection position, Find the position shift of the product itself at the time of imaging,
Position correction means (C) for correcting the position information of the image data D stored in the first image data storage means (B), and image data of a pattern having the same design and no positional deviation is stored as basic data d _0. A second image data storage means (E) for performing the search, and a search area Q including the inspection pattern R substantially at the center are set, and a detection area q having the same size as the inspection pattern R is set.
Are sequentially shifted in the search area Q, the detection data d on the image data D corresponding to the detection area q and the basic data d from the second image data storage means (E) _The template matching means (F) for checking the matching degree between both data by comparing ₀ with each pixel, and the detection when the matching degree is the highest by the comparison by the template matching means (F). Position determination means (G) for obtaining the amount of deviation of the symbol from the shift position of the area q is provided.

[Action]

When the product is conveyed to the inspection position, the pattern of the product (1) or a part of the pattern is set as the inspection pattern R by the camera (A), and the region 41 including the inspection pattern R is imaged. The image data D is stored in the first image data storage means (B).

Next, the positional deviation of the product (1) is obtained from the separation distance of the product (1) in the image data D with respect to the line flow direction and the separation distance with respect to the direction orthogonal to the line flow direction, and the position information of the image data D is obtained. It is corrected by the position correction means (C).

Further, the image data of the pattern having the same design and no positional deviation is stored in advance in the second image data storage means (E) as the basic data d ₀ .

Next, the search area Q is set so as to include the inspection pattern R substantially at the center, and the detection area q having the same size as the inspection pattern R is sequentially shifted in the search area Q. At this time, the detection data d on the image data D corresponding to the detection area q is read one after another, and the read detection data d is read from the second image data storage means (E). The basic data d ₀ is compared with each pixel, and the matching degree between both data is checked by the template matching means (F).

The shift position of the detection area q when the matching degree is the highest by the comparison by the template matching means (F) indicates the existing position of the inspection pattern R. Therefore, the position determining means (G) obtains the difference between this position and the position of the basic data d ₀ as the amount of deviation of the symbol.

By the way, when the detection area q is shifted in the search area Q, if a plurality of images are shifted, the shift position where the degree of matching between both data becomes the maximum is detected early.
The accuracy of the amount of deviation detected at that time is poor (errors of a plurality of pixels at maximum). On the other hand, if the image is shifted by one image, the amount of deviation can be detected with high accuracy, but it takes too much time.

Therefore, according to the present invention, as described in claim 2, the template matching means (F) first shifts the detection area q in the search area Q by m pixels to obtain a matching degree. The second shift centering on the position of the detection area q at this time is searched for the highest shift position.
Search area Q ′ (<Q) is set, and the detection area q is shifted by n (<m) pixels with respect to the second search area Q ′ to find the highest matching degree. By sequentially narrowing the search region, even if the shift amount of the detection region q is finally 1 pixel, the shift amount can be detected with high accuracy in a short time.

〔Example〕

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

Reference numeral 1 denotes a soap to be inspected, which is conveyed leftward in the drawing at a constant speed by a conveyor 2. 3 and 4 are sensors that inspect whether or not the soap 1 has been conveyed to the inspection position. Reference numeral 5 is an illuminating lamp for illuminating the soap 1 at the inspection position, and uses a high-frequency fluorescent lamp to eliminate the flicker associated with the commercial frequency. Reference numeral 6 denotes a camera using a CCD image pickup device, which captures an image of the upper surface of the soap 1 at the inspection position.

Reference numeral 7 denotes a CPU (central processing unit) for centrally controlling the present apparatus, and internally has an image processing unit 7a which functions at the time of image processing described in detail later. 8 is a ROM (read only memory) that stores the control program executed by the CPU 7.
Is. Reference numeral 9 denotes a signal input section, and the detection signals from the sensors 3 and 4 are taken into the CPU 7 via the signal input section 9. Reference numeral 10 is an image memory for storing a video signal from the camera 6, and 11 is an image monitor display for monitoring an image pickup screen of the camera 6. 12
Is a keyboard for inputting various setting conditions and the like. 13 is a discharge device for discharging the soap 1 to the side from the flow of the line, 14 is a signal output unit of the CPU 7, and when a defect due to the displacement of the display pattern is detected by the inspection of this device, A predetermined discharge signal is sent to the discharge device 13 and a release signal is output to the camera 6 when the sensors 3 and 4 detect that the soap 1 has reached the inspection position.

Reference numeral 15 is a measurement result display for displaying the inspection result of this apparatus, and 16 is a floppy disk device for storing the inspection result as data.

Next, the operation of the apparatus having the above configuration will be described with reference to the flowchart of FIG.

First, the basic pattern required for the inspection described below will be described. FIG. 4 shows an image of the soap 1 picked up by the camera 6, and the outer frame 41 is an image pickup area of the camera 6. In the soap 1, “bac” is a trade name, “WHITE” is a trade name, and the area below the soap 1 is a striped pattern.
Pattern to be inspected (hereinafter referred to as inspection pattern R)
Any of the above-mentioned characters or patterns may be adopted as, but in the present embodiment, the character "a" in the center of "bac" was used. As a result, as a reference pattern for comparison,
It is necessary to previously register image data of a pattern having the same pattern as the inspection pattern R and having no positional deviation as the basic data d _{0, and} as information for this basic pattern R ₀ , it is shown in FIG. 5 (A). As described above, the pixel data for the area of the character "a" and the data of the distances x and y of the character "a" from the edge of the soap 1 are included, and the registration method will be described later.

Now, in step S1, when the type of the soap 1 to be inspected is selected by the keyboard 12, the desired one is read from the basic pattern R ₀ registered for each type from the floppy disk device. In the next step S2, the detection signal from the sensors 3 and 4 is waited, the soap 1 comes to a predetermined inspection position, and the predetermined inspection signal is taken into the CPU 7 from the sensors 3 and 4, and the camera 6 in step S3. The image data D of the imaged soap 1 is taken into the image memory 10.

In step S4, it is determined whether or not the soaps 1 are successively conveyed to the inspection position. If the soaps 1 are continuously conveyed, the process proceeds to the next step S5. / 60 seconds is required, so when using a camera with a shutter, when the release signal is input, the shutter is released when the read pixel comes to the beginning of the field, so in the worst case, that is, the read pixel is Immediately after passing the beginning of the field, it will wait about 1/60 second until the shutter is released next time. Line speed is 40
In the case of m / min, as shown in FIG. 4, the soap 1 moves 11 mm in 1/60 seconds. So this step
In S5, one edge L of the soap 1 is detected from the image data D of the soap 1 stored in the image memory 10 and the separation distance X of the soap 1 in the imaging region 41 with respect to the line flow direction is detected.
(Shown in FIG. 5 (B)), and the separation distance Y (shown in FIG. 5 (C)) of the soap 1 with respect to the direction orthogonal to the line flow direction is set and set accurately at the measurement position. The image data D of the soap 1 is address-shifted on the image memory 10 from the distance measured in the same manner for the soap 1, and the position is corrected.

There are random shutter cameras that release the shutter at the same time as the release signal is input, but even with this camera, the shutter is released with a simple position detection system that detects the soap 1 moving at high speed with an optical sensor. Since the detected position of the soap 1 at a given time includes an error of several millimeters, the position correction as described above is indispensable. Step
In S6, as shown in FIG. 5 (D), the search area Q including the character "a" which is the inspection pattern R at the center is the image data D.
Image memory 1 storing (data of imaging area 41)
Is set for.

In the next step S7, as shown in FIG. 5 (E), the detection areas q having the same size as the inspection pattern R are successively shifted with respect to the search areas Q on the image memory 10, and the detection areas at this time are detected. Template matching is performed to check the degree of matching between the data on the image memory 10 (referred to as detection data d) corresponding to q and the basic data d ₀ from the pattern R ₀ described above. The template matching process will be specifically described with reference to the pattern diagrams of FIGS. 6 to 8.

FIGS. I-1 to I-9 in FIG. 6 show the first stage of template matching, and in FIG.
The region of × 12 pixels corresponds to the search region Q shown in FIG. 5D, and the white or black dots in the region R of 3 × 3 pixels surrounded by a circle indicate the inspection pattern R to be inspected. When the white dot and the black dot in each pixel are represented by "0" and "1", this inspection pattern R has the following pixel information.

Further, the 3 × 3 pixel area surrounded by the broken line circle is the above-mentioned detection area q, and it is examined how much the detection data from this detection area q matches the basic data from the basic pattern R _0. However, in order to make the matching determination described below easier to understand, the detection area q
The pixel information of the basic pattern R ₀ is shown in FIG.

In FIG. I-1, the detection data read from the detection area q is Then, in order to check the degree of matching with the basic data, subtraction is performed between the corresponding pixels, as shown in the following table.

As can be seen from the above table, the number of matched pixels is found by counting the number of subtraction results that are 0. In pattern I-1, the number of matching pixels is four.

When the matching determination in FIG. I-1 is completed, the detection area q shifts to the right by four pixels, as shown in FIG. I-2. Since the detection data in FIG. I-2 are all “0” as in the previous case, the number of matching pixels is four.

When the detection area q reaches the right end as shown in the next FIG. I-3, the detection area q returns to the left end and shifts downward by four pixels as shown in the next I-4. In the next figure I-5, the detection area q and the inspection pattern R are matched in some pixels. The detection data at this time is The number of matching pixels that have become 0 when the subtraction is performed with the basic data is 6 and the patterns I-1 to I-
The degree of matching is higher than in the case of 4.

Since the number of matching pixels in each of FIGS. I-6 to I-9 below is four, the degree of matching is highest in the comparison in FIG. I-5 in the first-stage matching. Therefore, as shown in Fig. I-10, a region Q'which is expanded by two pixels around the detection region q in Fig. I-5 is used as a search region in the second stage love shown in Fig. 7. .

In Fig. II-1, the detection area q starts from the upper left in the search area Q'and this time shifts by two pixels. Also in this case,
As in the first step, when the number of matching pixels is checked, II-
1, II-4, II-7 and II-9 are four, whereas II-2, II-3, II-5 and II-6 are six, and the matching degree is high. There is. In this embodiment, in order to simplify the explanation, the image data is set to 12 × 12 14
Since the number of pixels is 4 and the standard image data is 9 pixels of 3 × 3, the matching degree is the same in the above-mentioned FIGS. II-2, II-3, II-5, and II-6. Q is 60 × 60 3600 pixels, and the detection area q is 28 × 28.
Since it is 784 pixels, the matching degree becomes highest in any matching. Here, the following discussion will be made assuming that the degree of matching is the highest in Fig. II-2.

As shown in Fig. II-10, the detection area q
A search area Q ″, which is an area expanded by one pixel around the center, is set, and then the process proceeds to the third step shown in FIG.

In the third stage, the detection area q is shifted in the search area Q ″ by one pixel from the upper left. The matching degree in this case is as shown in FIG. Is the highest, and the number of matching pixels is 9. Therefore, in the next step S8, as shown in Fig. III-10, the position of the detection area q in Fig. III-9 is detected. Then, the detected position is set as the position of the character "a" which was the inspection pattern R of the soap 1, and the inspection is performed from the position and the distance x, y (shown in FIG. 5A) with respect to the basic pattern R ₀ . Target soap 1
The deviation amount of the display symbol in is calculated. In step S9, it is determined from the magnitude of the deviation amount whether the product is a good product or a defective product. When the deviation amount is determined to be a defective product larger than a specified value, the process proceeds to the discharging process of step S10.

FIG. 3B is a subroutine showing the discharging process of step S10. First, in step S21, the soap 1 is removed from the line by the discharging device 13, and the next step
In S22, it is determined whether or not such discharging operation is continuous, and if the discharging operation occurs sporadically, Step S25
Then, the display indicating that the discharging operation is performed is displayed on the measurement result display display 15. On the other hand, if the discharge operation continues, it is determined that there is a problem in the production line, and the step S2
The process proceeds from step 2 to step S23, the production line is stopped, and an error is displayed in step S24.

Returning to FIG. 3 (A), in the next step S11, the deviation amount and the like are displayed on the display display 15 as the measurement result, and when the end key is pressed from the keyboard 12 in the next step S12, this detection mode is detected. Is completed and the process returns to the original step S1. If not, the process returns to step S2, and the soap 1 sent to the inspection position is subjected to the same inspection as described above.

In this way, in the inspection process, the positional deviation of the display pattern is inspected in real time with respect to the soap 1 flowing through the line, and the amount of the deviation is displayed on the measurement result display display 15. Even in the initial operation of registration, since only the deviation amount of the display pattern is displayed,
By checking the deviation amount, it is possible to determine whether the product is a good product or a defective product. As a result, the inspection pattern R for the soap 1 determined to be non-defective may be registered in the floppy disk device 16 as the basic pattern R ₀ .

In the template matching described above, the comparison operation is divided into three stages, and search regions Q, Q ′,
Since Q ″ is set, the total number of comparisons to be made for one soap 1 can be reduced. For example, when the search area Q is 60 × 60 pixels and the detection area q is 28 × 28 pixels,
The range in which the detection area q is moved for pattern comparison in the search area Q is 32 ÷ 4 because it is compared every 4 pixels in the first stage.
= 8 times of movement, including 9 times including the comparison at the origin, 9 times in the horizontal direction and 9 times in the vertical direction for a total of 81 comparisons with the basic pattern.

In the second stage, the comparison with the basic pattern is performed 9 times for every 2 pixels centering on the place where the best match is obtained in the first stage.

In the third stage, the comparison with the basic pattern is performed nine times for each pixel, centering on the place where the best match is obtained in the second stage.

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

On the other hand, when this is performed by the normal template matching method for each pixel, it is necessary to perform a comparative movement of 60−28 = 32 32 pixels in the horizontal direction and 32 pixels in the vertical direction. Is required, which is 33 × 33 = 1089 times.

As described above, in the template matching method applied to the present invention, the number of comparisons can be reduced to about 1/11 of the ordinary one, and high-speed inspection can be performed. Therefore, a large amount of 250 to 300 pieces per minute flows like soap 1. Even on a line, the inspection device can be realized by an inexpensive computer device.

〔The invention's effect〕

As described above, according to the present invention, the product conveyed to the inspection position is imaged by the camera, and the image data is based on the positional deviation amount of the product at the time of imaging which is understood from the comparison between the image data and the reference data. Since the position is corrected, it is possible to use an inexpensive camera with a shutter, which causes a time lag during imaging. Then, for this position-corrected image data,
By checking the degree of matching between the detection data read while sequentially shifting the predetermined read area and the basic data that has been registered in advance and has no positional deviation by the template matching method, the design of the product or the design Since a part of the positions is detected and the quality is determined to be good or bad, it is possible to detect the position shift of the display pattern for various products by simply changing the basic data to be registered. Further, when comparing patterns by template matching, the detection area q is shifted not by one pixel but by several pixels to detect a rough position of the design or a part of the design to be detected, and then the detected position is detected. By narrowing the search area Q'to the center and adopting a similar pattern comparison method below,
The number of pattern comparisons can be significantly reduced, and thus the present apparatus can be realized by an inexpensive computer apparatus having a slow processing speed.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims of a display pattern deviation inspection device of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, and FIGS. 3 (A) and 3 (B) are FIG. 4 is a flow chart showing the control operation of the apparatus shown in FIG. 4, FIG. 4 is a view showing an image of soap taken by the camera in the apparatus shown in FIG. 2, and FIG. 5 (A) is for the soap shown in FIG. The figure which shows a basic pattern, FIG.5 (B) and FIG.5 (C) are the figures for demonstrating the position correction of the imaged soap, FIG.5 (D) was set with respect to the inspection pattern in soap. FIG. 5 (E) is a diagram showing a search area, FIG. 5 (E) is a diagram showing template matching, and FIG. 5 (F) is a diagram showing a shift amount as an inspection result.
6 to 8 are pattern diagrams showing the comparison process performed by template matching. 1 ... Soap, 2 ... Conveyor, 3,4 ... Sensor, 5 ... Illumination lamp, 6 ... Camera, 7 ... CPU, 7a ... Image processing section, 8 ... ROM, 10 ... Image memory , 11 …… Image monitor display, 12 …… Keyboard, 13 …… Ejection processing, 15 …… Measurement result display, 16 …… Floppy disk device.

Claims (2)

[Claims] 1. A device for inspecting a positional deviation of a product conveyed on a line or a wrapping paper of the product, which inspects the product or a part of the product conveyed to an inspection position. An area 41 including a pattern R and including the inspection pattern R
(A) for imaging the image, and image data D of the imaging region 41 imaged by the camera (A)
A first image data storage means (B) for storing the product, and a separation distance with respect to the line flow direction of the product in the image data D stored in the first image data storage means (B) and a direction orthogonal to the line flow direction. The position correction means (C) that corrects the position information of the image data D stored in the first image data storage means (B) from the separation distance with respect to the image data of the pattern having the same design and no positional deviation. A second image data storage unit (E) for storing the basic data d ₀ and a search area Q including the inspection pattern R at the center are set, and a detection area q having the same size as the inspection pattern R is set.
Are sequentially shifted in the search area Q, the detection data d on the image data D corresponding to the detection area q and the basic data d from the second image data storage means (E) _The template matching means (F) for checking the matching degree between both data by comparing ₀ with each pixel, and the detection when the matching degree is the highest by the comparison by the template matching means (F). A deviation checking device for a display symbol, comprising: a position determining means (G) for obtaining a deviation amount of the symbol from the shift position of the area q. 2. The template matching means (F)
By shifting the detection area q by m pixels,
A second search area Q '(<Q) centered on the position of the detection area q when the degree of matching is maximized is set, and the detection area q is set to n ( <M)
The display pattern deviation inspection device according to claim 1, wherein the operation of shifting pixel by pixel is repeated until the shift amount of the detection region q becomes 1 pixel.