JPS5828618B2 - pattern inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pattern inspection device suitable for application to a label inspection device that simultaneously inspects a plurality of labels attached to a product or its packaging using a plurality of image sensors. It is.

Conventionally, as a method for identifying patterns of objects that move continuously on a production line, standard patterns are memorized in advance, and by superimposing the pattern to be inspected detected by an image sensor on this standard pattern, the quality of the figure to be inspected is determined. A pattern matching technique is used to test.

Pattern inspection devices using this method are widely used for inspecting the quality of bottle labels and the appearance of product boxes.

This type of conventional example is disclosed in, for example, Japanese Patent Application Laid-open No. 53-69538 filed by the applicant of the present invention, and also, for example, in "Electronic Technology Vol. 20, published by Nikkan Kogyo Shimbun on May 1, 1978. In the conventional example of Article 107 and Rule 109 of ``No. 5'', when two or more labels affixed to products are to be inspected, one image sensor is used with an expanded field of view, or Alternatively, a method is used in which a plurality of image sensors are used for each label to be inspected.

However, the former method has its own technical limitations in terms of resolution when it comes to expanding the field of view;
Since it is not possible to inspect various products whose labels are attached at different positions, the latter method, that is, a method using two or more image sensors, is exclusively used.

In this case, the inspection results of each label are of course logically combined and a comprehensive judgment is made in the end, but each label is inspected independently to create individual logical information. Therefore, each image sensor operated independently.

That is, the conventional example has a configuration in which a plurality of independent systems of inspection apparatus are operated corresponding to the labels to be inspected.

By the way, in recent years, even higher standards have been required for the appearance of products, and it is not just standard compliance for each label, but also standard compliance for the relative relationship of label affixing positions. Became.

In such a case, if one were to test the relative relationships between labels by simply extending the conventional technology, extremely complex arithmetic operations would be required, resulting in large hardware costs and extremely long processing times. .

Normally, this type of equipment inspects continuously moving patterns, so random positional deviations due to various factors inevitably occur, and it takes a considerable amount of time to correct such random positional deviations. Since processing time must be allocated and the movement speed of the patterns is relatively fast, typically several pieces per second, it is difficult for this type of device to dedicate a longer period of time to scanning each label. This makes it virtually impossible.

Furthermore, if the relative relationship of labels is to be inspected by simply extending the conventional technology, each image sensor must be installed with extremely high precision, and such high precision must be maintained over a long period of time. It also comes with the difficulty of not having to do so.

The present invention has been made to solve the various problems mentioned above, and its purpose is to provide a pattern inspection device that is inexpensive, capable of high-speed operation, and that can obtain highly reliable inspection results. It is about providing.

According to the present invention that achieves the above object, all of the plurality of image sensors installed corresponding to the pattern to be inspected are controlled to operate synchronously, and all the signals of the pattern to be inspected are transmitted to any one of them. The detected pattern tip appearance point for each pattern is stored in the memory as a reference.

With such a configuration, when multiple patterns are stored in the memory, the relative position information of each pattern is also stored at the same time, and therefore a complex circuit is required to calculate the relative position of each stored pattern. and computation time can be completely eliminated.

Hereinafter, further details of the present invention will be explained with reference to the drawings.

First, an outline of an embodiment of the present invention will be explained with reference to FIG.

As shown in the figure, there is a bottle 9 of alcoholic beverages, etc., to which product labels (patterns to be inspected) 1 and 2 are attached.

For example, the bottle 9 is blackish brown, and the product labels 1 and 2 have characters, figures, symbols, etc. printed in black on a white or yellow base.

Product labels 1 and 2 are affixed to the body and shoulder of the bottle 9, respectively, but from the viewpoint of pattern resolution, etc.
Two TV cameras 3.4 (generally image sensors)
The structure is such that each label can be manipulated.

The bins 9 are passed in front of the television camera at a rate of several bins per second by a conveyance device (not shown).

The position detectors 7 and 7' have labels 1 and 2 attached to the television camera 3.
．． 4 is detected from the position O of the bottle 9, and a signal is sent to the identification circuit 8.

Upon receiving this, the identification circuit 8 detects the momentary illumination device 5 when the built-in camera 1 drive control circuit generates the next vertical synchronization signal.
, 6 are turned on, and the appropriateness of the pattern and relative positional relationship of the labels 1 and 2 is inspected by the method described below based on the image sensor output of one field immediately after the lighting.

FIG. 2 is a functional block diagram of one embodiment of the present invention, and FIG. 3 is a waveform diagram for explaining the operation of FIG. 2.

The television cameras 3 and 4 have a common camera 1 drive control circuit 3.
It is driven by a vertical synchronization signal a (see FIG. 3) supplied from 1 to 7, and always performs synchronous scanning so as to scan the same position on each exercise tube surface at the same time.

In the following, for convenience of explanation, label 1 will be referred to as a main label and label 2 will be referred to as a slave label, and the circuit parts to be tested will be referred to as a main pattern system and a slave pattern system, respectively, as necessary.

For example, when cameras 3 and 4 are expressed in this way, camera 3 is the main camera and camera 4 is the slave camera.

The signal outputs (pattern signals to be inspected) of the main camera 3 and slave camera 4 are output from analog-to-digital (A-D) conversion circuits 34 and 34, respectively.
．． 35, but regarding the output of the main camera 3,
Furthermore, it is also supplied to the main pattern tip detection circuit 36.

Each of the cameras 3 and 4 is connected to a conversion circuit 34. The sensitivity is adjusted so that no effective video signal can be output except when the instantaneous illumination devices 5 and 6 are turned on. 35. The main pattern tip detection circuit 36 is
Except for the above-mentioned lighting, the output function is substantially inactive.

The position detectors 7, 7', which are composed of a pair of light emitting diodes and phototransistors, etc.
2 has entered the predetermined field of view of cameras 3 and 4.
When detected from the position, a detection signal b (see FIG. 3) is sent to the instantaneous illumination control device 32.

As shown in FIG. 3, the instantaneous illumination control device 32 controls the camera drive control circuit 31 after r hours after receiving the detection signal.
Upon receiving the first vertical synchronizing signal a supplied from the synchronous lighting device 1, it sends a lighting signal C to the instantaneous lighting devices 5 and 6.

By turning on the instantaneous illumination devices 5 and 6, the signal outputs of the cameras 3 and 4 are brought to an appropriate level to enable subsequent processing.

On the other hand, the determination control circuit 33 receives the signals from the position detectors 7 and 7' and determines the first field after the position of the bin 9 is detected based on the vertical synchronization signal a as shown in FIG. Create an effective field period signal d and convert it to A
-D conversion circuits 34, 35, main pattern tip detection circuit 36
, memory control circuit 37, 38 (by sending this,
The circuits 34, 35, . . . 38 are activated.

Therefore, when the effective field period starts, camera 3,
The video output (pattern signal to be inspected) No. 4 is converted into a binary or multi-value digital video signal by A-D conversion circuits 34 and 35, and then sent to a main pattern tip detection circuit 36, which will be described below.
Waiting for the arrival of the main pattern leading edge detection signal f from the main pattern leading edge detection signal f, the main pattern leading edge detection signal f is inputted to the memory control circuits 37 and 38, respectively.

The main pattern leading edge detection circuit 36 is activated by the effective field period signal d, and integrates the image signal level of the main pattern, which is the video output of the main camera 3, every horizontal scanning period, and when this integrated value reaches a predetermined level. This is a circuit that determines that the pattern has started when it exceeds the threshold.

That is, this circuit has a function of separating the pattern and the background and extracting the starting point of the pattern.

Further details of this type of pattern tip detection circuit are disclosed in Japanese Unexamined Patent Publication No. 54-24546 filed by the applicant of the present invention.

When the memory control circuits 37 and 38 receive the main pattern leading edge detection signal f, the memory control circuits 37 and 38 convert the digital image signals output from the A-D conversion circuits 34 and 35 into horizontal and vertical directions under the control of the screen division circuit 45. Start the digitization operation of the screen to divide it into unit picture elements.

As a result, the main pattern signal and the sub-pattern signal, which have been digitized both grayscale and spatially, are stored in the test pattern memories (to be precise, digitized test pattern memories) 40 and 41, respectively.

In this way, since the main pattern tip detection signal f indicating the main pattern starting point (thereby activating the memory control circuits 37 and 38), the pattern to be inspected memo 1J40, 4
2, the main pattern and the sub-pattern to be inspected, each of which is based on the starting point of the main pattern, are stored.

FIG. 4 is a diagrammatic representation of this situation.

The video output 3' of the main camera 3 at the moment when the position detectors 7 and 7' operate (this is the video output 1' of the main label 1 as shown in the figure).
The video output 4' of the slave camera 4 includes the video output 2 of the slave label 2 as shown.

Note that the arrow in the figure indicates the direction of movement of the label.

The image signals 3', 4' are stored in the inspected pattern memo IJ 40, 41 by the position detector 7. This is carried out after the operation of T and waits for the generation of the raw pattern tip detection signal f, and the content 4 stored in the pattern memory 40 and 41 to be inspected is
0', 41' are image outputs 3', 4' after a certain time has elapsed
The labels 1" and γ each correspond to 4σ
, 41', the figure is on the left side.

In the figure, the combination A and B is when the relative position between the main label 1 and the slave label 2 is appropriate, and the combination A and C is when the relative position between the main and slave labels is too far apart and is inappropriate. It is.

In any case, the storage of the Belhattern in the pattern memory 41 to be inspected is started after the generation of the pattern tip detection signal f for the main label.

Now, in FIG. 2, standard pattern memories 39 and 42
Internally, main and sub-digitized standard patterns are stored that are appropriate both individually and in their relative positions.

Such accumulation of appropriate patterns can be performed by any appropriate method, but as an example, when the switch 46 is switched to the memory 39 side and the switch 47 is switched to the memory 42 side, appropriate patterns are stored. Good quality camera 3, 4
You can also do this by shooting with .

After storing the standard pattern (to be more precise, the digitized standard pattern), the switches 46 and 47 are respectively switched to the test pattern memo 1140 and 41 side, and the test pattern for the test label is stored in the method described above.

When the storage of the pattern to be inspected is completed, the determination control circuit 33 sends a determination timing control signal e (see FIG. 2) to the comparison determination circuits 43 and 44.

Upon receipt of this, the comparison judgment circuit 43 reads out the standard pattern and the pattern to be inspected for the main pattern from the memory 39.40 and performs a comparison judgment between the two. "'O" is outputted to one input terminal of the AND gate 48.

In parallel with this, the collation determination circuit 44 outputs the memo 1J4L42.
The standard pattern and the pattern to be inspected are read out for the slave pattern, and a comparison judgment is made between the two. If they match, a logic "1" is output, and if they do not match, a logic 11011 is output to the other input terminal of the AND gate 48. .

Therefore, the AND gate 48 outputs a logic "1" signal indicating that the product is good only when both the master and slave patterns are correct and the relative positions of the master and slave are also appropriate. .

Note that the matching judgment circuits 43 and 44 may be of any suitable type as long as they are logic circuits that compare and match patterns. It may be of a type that counts picture elements having a difference in shading, or of a type that counts picture elements having a predetermined difference in shading for one or more predetermined memory areas.

As is clear from the above description, according to the present invention, the adaptation of the main pattern, the sub pattern, and the mutual relationship between the main pattern and the sub pattern can be performed without using any means for matching the main pattern and the sub pattern. The gender can be tested.

Furthermore, according to the above-mentioned embodiment in which standard patterns are accumulated by photographing non-defective products by switching the switches 46 and 47, even if there is some error in the installation of the cameras 3 and 4, the difference between non-defective products and the product to be inspected is Since camera installation errors are offset during verification, a considerable amount of error in camera installation can be tolerated, and the camera installation mechanism and adjustment are simple, with the advantage of requiring less expense.

In the embodiment described above, the standard pattern and the pattern to be inspected are matched with respect to the pattern shading information. , it is clear that the effects of the present invention are achieved.

FIG. 5 is a functional block diagram of one such embodiment.

The difference between FIG. 5 and FIG. 2 is that feature extraction circuits 51 and 52 are inserted between the A-D conversion circuit 34 and the memory control circuit 37, and between the A-D conversion circuit 35 and the memory control circuit 38, respectively. The only difference is whether or not it is, and all other parts are common, so there is no need for redundant explanation of the other parts.

In FIG. 5, feature extraction circuits 51 and 52 create gray-scale and spatially digitized signals based on the outputs of the A-D conversion circuits 34 and 35 and the screen division signal from the screen division circuit 45. Then, predetermined features are extracted from this, and the coordinate information is transferred to the inspected pattern memos IJ 40 and 41 via the memory control circuits 37 and 38.

The above feature extraction items include, for example, figures such as circles and rectangles having a predetermined size, characters, or straight lines with a predetermined slope.

In this way, the detailed coordinate information of the characteristic pattern is memorized, and the tip detection signal of the main pattern is also used for the sub pattern as its reference coordinate.

In the above description, for convenience of explanation, the expressions "main pattern" and "sub pattern" are used, but which pattern is the main pattern and which is the sub pattern may be determined individually depending on the case.

Also, although we have explained two patterns, generally there are three patterns.
It is clear that it can also be applied to more than one pattern.

Also, although I explained using a TV camera as a sensor, it is also common (
It is clear that a two-dimensional solid-state camera or other two-dimensional electronic scanning photoelectric conversion device may be used.

Furthermore, in order to save memory capacity, it is clear that a portion of the pattern to be inspected may be stored in the memory, collated and judged, etc.

As described above in detail, the pattern inspection apparatus of the present invention operates the main and slave image sensors installed corresponding to the master and slave patterns to be inspected in synchronization, and the master and slave image sensors are operated synchronously with respect to the main pattern tip detection point. Since each pattern is stored in memory, there is no need for any complicated arithmetic circuit to detect the relative position between the stored main and slave patterns.
Moreover, high-speed pattern inspection is possible.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an outline of an embodiment of the present invention, FIGS. 2 and 5 are functional block diagrams of an embodiment of the present invention, and FIGS. It is a conceptual diagram explaining the operation|movement of a figure. 1.2...Label, 3,4...Image sensor, 8...Identification circuit, 31...
Camera 1 drive control circuit, 36...Pattern tip detection circuit, 40, 41...Test pattern memory, 39.42...Standard pattern memory, 4
3, 44... Verification judgment circuit, 48...
And gate.

Claims (1)

[Claims] 1. A plurality of image sensors installed corresponding to a plurality of patterns to be inspected, means for synchronously scanning the plurality of image sensors, and a pattern to be inspected signal output from each image sensor. means for creating a digitized pattern signal to be inspected through digitization processing; and means for detecting a starting point of a pattern signal for any one of the plurality of pattern signals to be inspected to generate a pattern tip detection signal; , means for receiving the pattern tip detection signal and storing each of the digitized pattern-to-be-inspected signals in a corresponding digitized pattern-to-be-inspected signal memory; and a digitized standard pattern corresponding to each digitized pattern-to-be-inspected signal. a digitized standard pattern signal memory for accumulating signals; a comparison and determination means for comparing and determining the contents of the digitized test pattern signal memory and the contents of the digitized standard pattern signal memory and outputting the determination result; 1. A pattern inspection device comprising: logical means for generating a pattern inspection result by logically combining the determination results of the above. 2. The digitized standard pattern signal memory comprises means for storing each of the digitized pattern signals to be inspected for the pattern to be inspected for which the pattern inspection result is to be good. The pattern inspection device according to item 1. 3. The pattern inspection apparatus according to claim 1, wherein both the digitized inspected pattern signal and the digitized standard pattern signal are created for only a portion of the inspected pattern.