JPS61239105A - Inspecting method of printing pattern - Google Patents

Abstract

PURPOSE:To inspect the quality even in case of a fine pattern of a printing character, etc., and even if there is a dispersion in a size of printing, by generating plural pieces of window groups so that the quality can be decided at every window. CONSTITUTION:A television camera 11 brings a pattern 1 of a printing character, etc. and converts it to an electrical signal. This signal is converted to a binary digital signal in accordance with its variable density level by an A/D converting part 12, and stored in an image memory 14. A feature extracting part 15 extracts various feature data containing an area data of the pattern 1 from the memory 14, and a processor 16 executes various operation processings containing a comparison, based on this data. A window generating part 13 sets a window, based on an instruction from the processor 16, and selects the feature data to be read out of the memory 14. A position where this window is to be generated, and its shape, etc. are stored in advance in the memory 14, or window information is given to the device 16 through an I/O interface part 17 by an operation display part 18, and brought to a setting processing, and thereafter, given to the window generating part 13.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an inspection method that images a printed pattern, processes the image, and inspects mainly local defects such as cuts, chips, or blurs in the printed pattern. Regarding.

[Conventional technology]

Conventionally, quality inspection of printed patterns using image processing technology has been carried out exclusively by determining the area value of the entire printed pattern and determining whether or not this area value is within a predetermined tolerance range.

[Problem that the invention seeks to solve]

However, although this method can roughly inspect the quality of printed patterns, it is difficult to inspect defects due to partial concave or convex portions of the pattern or to inspect fine patterns such as printed characters for differences.

This is because in patterns such as printed characters, the area value of the characters varies greatly depending on the degree of ink application, etc., so it is not possible to properly determine criteria for distinguishing between good products and defective products.

Therefore, it is an object of the present invention to enable accurate inspection of the quality of even fine patterns such as printed characters or variations in print thickness.

[Means for solving problems]

Window setting means for setting a group of windows of a predetermined shape (chain window) adjacent to each other in the printed butter to be inspected, and area data for extracting area value data occupied by the printed pattern portion for each set window. An extraction means and a calculation means for performing various calculations including comparison with a set value based on the area value data are provided.

[Effect]

After capturing an image of the print pattern with an imaging device such as a television camera and converting the captured image signal into a binary signal according to the density level, a predetermined number of adjacent windows of a predetermined shape covering at least the width of the pattern are formed along the shape of the pattern. The pattern area value is determined for each window by setting the pattern area value, and depending on whether or not this area value is within a predetermined tolerance range, mainly local defects such as printing chips, cuts, scratches, and protrusions can be detected with high precision. Try to get it. In addition, the judgment is based on the difference in pattern area values between adjacent windows, and is the pattern area value a predetermined standard? By appropriately using the determination based on the number of windows in '3, the determination based on the envelope window, etc., the content of determination is enriched and accuracy is improved.

〔Example〕

Figure 1 is a reference diagram for explaining the invention in detail;
The figure is a block diagram showing the configuration of an image processing apparatus in which the present invention is implemented, and FIG. 3 is a reference diagram for explaining a specific sequence of defect inspections.

First, FIG. 2 will be explained. In addition, in the same figure,
1 is a printed pattern to be inspected, 11 is an imaging device such as a television camera, and 12 is an analog/digital (A/D)
) conversion section, 13 is a window generation section, 14 is an image memory, 15 is a feature data extraction section, 16 is a processing device such as a microprocessor, 17 is an input/output (Ilo) interface section, and 18 is an operation display section. .

The television camera 11 images a pattern 1 such as printed characters,
Convert to electrical signal (image signal). This image signal is A/
The signal is supplied to the D converter 12, where it is converted into a binary digital signal according to its gray level, and stored in the dual cylinder memory 14. The feature extraction unit 15 extracts various feature data including area data of the print pattern 1 from the image memory 14, and the processing device 16 performs various calculation processes including comparison based on this feature data. The window generation unit 16 is
Window settings are made based on instructions from the processing device 16, and feature data to be read from the image memory 14 is selected. This window specifies the area to be observed or inspected on the imaging screen, and the position and shape of the area to be observed can be stored in advance in a predetermined memory, or can be entered using the 1104777147
Settings can be made by providing window information to the processing device 16 via the section 17. This window information is appropriately processed in the processing device 16 and then provided to the window generation section 13.

Note that the method for generating such a window is already known;
For example, it is shown in Japanese Patent Application Laid-Open No. 58-189780.

In FIG. 1, the win set in this way is a print pattern, and 21*22...2n is a window. In addition, in the same figure, 3 is the envelope window, 4
is the outside window area, i.e. the background, and 5 is the dirt (
noise).

That is, Fig. 1 shows the printing pattern (here, the number ``''
This is an example in which n circular windows (21, 22...2n) are set adjacent to each other along the shape of 2'') 1. The feature data extraction unit 1
Since pattern area data for each window can be obtained from 5, each area data can be compared with predetermined upper and lower limit setting values by the processing device 16.

Defects can be identified.

For example, if the printed pattern is chipped, cut, or faded, the area value will be less than a predetermined value. too
1. Each can be detected. Third
Figure (B) shows an example in which cuts 61 and 62 occur in the printed pattern 12, and Figure (C) shows an example in which chips or scratches 65 and protrusions 64 occur. Note that character pattern 11 in (a) of the same figure has a narrower character width than (b), but this is an example of a normal case. By selecting the upper and lower limit setting values appropriately, the character width can be adjusted. This shows that it is possible to perform a good/distortion test regardless of the condition. Also, partial defects such as chips, cuts, scratches, or protrusions as mentioned above can be detected not only from the area value occupied by one window (for example, find the difference between adjacent windows and compare this with another set value). Inspection accuracy can be improved by using methods such as The processing device 16 calculates the number of windows whose area values are within a predetermined tolerance range, and sets the number of windows to another set value. It is possible to determine whether the printed pattern of interest is of a different type by comparing with Needless to say,
This is similar to using the background value instead of the area value for each window.

Furthermore, although the envelope window 3 is generated in FIG. 1, the edges are automatically generated from the position data of the chain windows 21 to 2n, and are used to separate the print pattern 1 from the background 4. provided. In other words, by providing an enveloping window 5 of , anything outside the enveloping window of is considered to be a different pattern, and a pattern with this different pattern means that pattern 1 is a different pattern or that there is dirt 5. It can be treated as Note that the width of the envelope window 30 is one or more than the size of the individual windows 21 + 22...2n. -Set to be larger.

The above explanation deals with the case where there is only one pattern to be inspected, but if there are multiple printed patterns such as numbers or character strings, inspection can be performed by setting a chain window like the one above for each pattern separately. It is done. Further, although a circular window is set in the above example, it goes without saying that the shape is not limited to a circle.

〔Effect of the invention〕

According to this invention, a plurality of window groups are generated and the quality is judged for each individual window. Therefore, partial defects such as cuts, chips, scratches, or protrusions in the pattern can be detected based on the thickness of the pattern. It is possible to detect (related to By determining the difference in pattern WJ product values between windows and comparing this with a set value,
It is possible to further enhance the inspection content and improve accuracy. Furthermore, by determining the number of windows that satisfy the set criteria and by setting an envelope window that includes the chain window, there is an advantage that noise components such as differences in printed patterns and dirt can be accurately inspected.

[Brief explanation of drawings]

FIG. 1 is a reference diagram for explaining an embodiment of the present invention, FIG. 2 is a block diagram showing an image processing apparatus in which this invention is implemented, and FIG. 6 is a reference diagram for explaining a specific example of defect inspection. It is a diagram. Code explanation 1111112...Print pattern, 21-2n
... Window, 3 ... Envelope window, 4 ... Area outside the window (background), 5 ...
...Dirty, 61-64...Minor defect, 11...
...TV camera (imaging device), 12...Analog/digital (A/D) conversion section, 16...
...Window generation section, 14... Image memory,
15... Feature extraction unit, 16... Processing device (microprocessor), 17... Input/output (Ilo) interface unit, 18... Operation Display section. Agent Patent Attorney Akio Namiki Agent Patent Attorney Matsuzaki Quality 1 Figure 5 Home? ! 2 Figure

Claims (1)

[Claims] A method for inspecting a printed pattern, in which the printed pattern is imaged and subjected to image processing including at least binarization, and then inspected, the printed pattern being inspected in a predetermined shape adjacent to each other along the printed pattern of the processed image. By setting a predetermined number of windows for printing, determining the area value occupied by the print pattern portion for each window, and performing predetermined calculations for each window, including comparing the area value with the set value, A method for inspecting a printed pattern, characterized in that it enables mainly partial inspection of the printed pattern.