JPH0658688B2 - Print pattern recognition device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] Recognition target (print pattern printed by a dot printer)
This image is stored as a digital image in the frame memory, and a dictionary pattern that indicates the density measurement position is created using the recognition target creation data, and the image density in the frame memory is measured using this dictionary pattern. It is a print pattern recognition device for inspecting an image. As a result, in dot printing, a dictionary pattern is created to show the dot position by using, for example, the pattern data of a character generator for printer printing, so that it is possible to measure at an appropriate density position and to detect linear blurring defects in printing. The defect is surely detected.

[Industrial application field]

The present invention relates to a print pattern recognition device capable of inspecting a print pattern printed by a dot printer and surely detecting a linear blurring defect therein as a defect.

[Conventional technology]

Conventionally, one of the print quality defects of a dot printer is a linear blurring defect, and it is necessary to detect this defect in printer print inspection or the like. FIG. 7 is a diagram showing normal printing of a quadrangular pattern, and FIG. 8 is a diagram showing linear scratch defects with the same quadrilateral pattern. In FIG. 8, the linear blurring defect is formed in a white linear shape as a portion which is not printed in the lateral direction. This is because one or several of the dot pins forming the printer head have a protrusion defect. In order to detect this linear blurring defect, as shown in FIG. 8, print density values are added in the X-axis or Y-axis direction, and the maximum value (Max) and minimum value (Min) of each added value are calculated. determined good in the difference (Max-Min) value predetermined reference value when the _{(S L)} is smaller than _{(Max-Min <S L)} , greater than or equal to when a defective (Max-Min ≧ _{S L)} I was making a decision.

[Problems to be solved by the invention]

In the above conventional detection method, for example, as shown in FIG.
If there is a difference in the density between the print edge portion of the rectangular pattern and the print interior, it may be erroneously determined to be defective although it is a good product. In addition, as described above, the density difference between the print edge portion and the print inside is caused by
This is because the ink bleeds from each dot printed by the dot printer to the surrounding area and affects the surrounding dots. Further, when the dot printing is enlarged, as shown in FIG. 9, the density is different between the dot center and its periphery (the peripheral area formed by the ink bleeding as described above), and the image for detection is different. In the processing, when the read pixel interval smaller than the print dot interval is detected, the density values are different and the correct density determination cannot be performed. Further, there is a problem that it takes a long time to perform the adding process of all the pixels by making the read pixel interval small.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to reliably detect linear blurring defects and the like in printing, and it is also possible to shorten the processing time and detect at high speed. The purpose is to provide a device.

[Means for solving problems]

 FIG. 1 is an overall configuration diagram of the recognition device of the present invention.

In FIG. 1, 1 is a test pattern 2 based on a character generator 10 that generates test pattern data.
A dot printer for producing a test pattern 3, an image pickup device for picking up an image of the test pattern 2, 4 an image input circuit, 5 a frame memory, 6 a pattern matching circuit, 7 a density measuring circuit,
Reference numeral 9 is a dictionary creating circuit for creating the dictionary pattern 8 from the character generator 10. The dictionary pattern 8 created by the dictionary creating circuit 9 is the pattern matching circuit 6
Is output to the concentration measuring circuit 7.

[Work]

An analog image signal obtained by imaging the test pattern 2 with the image pickup device 3 during the print inspection is converted into a digital image signal by the image input circuit 4 and then stored in the frame memory 5. Using the pattern data of the character generator 10 which is the creation data of the test pattern 2, the dictionary creation circuit 9 indicates the dictionary pattern 8 that indicates the proper measurement density position.
It was created in advance. The test pattern 2 and the dictionary pattern 8 do not necessarily have to be created from the pattern data of the character generator 10, and the test pattern 2 and the dictionary pattern 8 correspond to each other, that is, each printing of the test pattern 2 is performed. It suffices that the center of the dot and each density measurement position of the dictionary pattern 8 match each other. Next, after the pattern position in the frame memory 5 is determined by the pattern matching circuit 6, the density measurement circuit 7 uses the dictionary pattern 8 to perform measurement. That is,
For the image positioned by the pattern matching circuit 6, the image density is measured at the density measuring position according to the dictionary pattern 8, and when a linear low image density portion exists along the scanning direction of the print head. This is determined to be a defective line defect. Since the dictionary pattern 8 corresponds to the dot position at the time of actual dot printing, proper density measurement can be performed, and defects such as linear blurring in printing can be detected.

〔Example〕

 An embodiment of the present invention will be described in detail below.

FIG. 1 is an overall configuration diagram of a recognition device according to the present invention.

In the present invention, first, the character generator 10 in which test pattern data is stored in a ROM or the like at the time of print inspection.
Based on the above, the dot printer 1 creates the print test pattern 2. The print test pattern 2 is picked up by an image pickup device 3 composed of a CCD or the like, the unevenness of the light amount and the like are corrected, and the image is obtained as an analog image signal. The analog image signal is converted into a digital image signal in the image input circuit 4 and stored in the frame memory 5 as a density value. On the other hand, based on the character generator 10, the dictionary creating circuit 9 creates a pattern indicating a position corresponding to the center of each print dot of the test pattern 2 as each density measurement position, and stores it as the dictionary pattern 8. Then, the pattern matching circuit 6 scans the dictionary pattern 8 created by the dictionary creating circuit 9 in the frame memory 5, detects the position of the pattern to be inspected, and outputs it to the density measuring circuit 7. The density measuring circuit 7 uses the dictionary pattern 8 to add the density in the same direction as the scanning direction of the print head, and inspects the linear blurring defect of the print according to the difference between the maximum value and the minimum value of the added value, The judgment result is output.

Next, the operation of the above embodiment will be described with reference to the operation flowchart of FIG. 2 and FIGS.

First, the test pattern 2 printed by the dot printer 1
Is acquired by the image pickup device 3 as an analog image signal. Further, it is converted into a digital image signal by the image input circuit 4 and stored in the frame memory 5 as an inspection target pattern. When the pattern to be inspected is a quadrangular pattern, as shown in FIG. 3, areas of high density (black circles) centered on the print dots are arranged in the X-axis and Y-axis directions. Further, the dictionary creating circuit 9 creates, as a dictionary pattern, a pattern indicating a density reading point from the character pattern of the character generator 10 corresponding to the test pattern. When this dictionary pattern is a quadrangular pattern, as shown in FIG. 4, the center of the print dot excluding the periphery of the print pattern is the read pixel (small white circle).
It is created so as to be located (above, S1 in FIG. 2). Next, the pattern matching circuit 6 scans the frame memory 5 using the dictionary pattern 8 created in the dictionary creating circuit 9 to perform positioning by pattern matching (above, S2 in FIG. 2). At the pattern position output from the pattern matching circuit 6, the density measuring circuit 7 adds the densities in the X-axis and Y-axis directions based on the dictionary pattern 8 created in the dictionary creating circuit 9 and counts the projected density value. At the same time, the number of projection bits is counted. That is, the density of the pattern to be inspected is read at the read pixel position designated by the dictionary pattern (density reading point designating pattern) while the positioning is performed by pattern matching, and the density is read on the Y axis in the X direction (same as the scanning direction of the print head). Direction) to form a pattern of density projection values f (y) as shown in FIG. 5 (a). Similarly, in the state where the pattern matching is performed, the number of read pixels of the dictionary pattern (density reading point designating pattern) is added in the X direction on the Y axis and projected as shown in FIG. 5 (b). A pattern having the number of bits n (y) is formed (the above is S3 in FIG. 2). Next, the density measuring circuit 7 calculates a normalized line density (f (y) / n (y)) from the density projection value f (y) and the number of projection bits n (y) (above, S in FIG. 2).
4). In the case of a wire dot printer, interference occurs between the pins due to the pattern to be printed, that is, the way in which the pins project from each other (the pins disappear).
Therefore, in addition to a simple square pattern, an arrow pattern, a spiral pattern, etc. are also used as a test pattern. However, by performing the above normalization, any pattern can be obtained. Can handle. For example, when the test pattern is an upward arrow as shown in FIG. 6 (a), the dictionary pattern (density reading point designating pattern) is as shown in FIG. As shown in FIG. 6 (c), the projected bit number pattern has different densities depending on the position. However, as shown in FIG. 6 (d), if the normalized line density is used, a pattern having no positional variation will be formed. That is, the density addition is normalized without being influenced by the test pattern. Next, the density measuring circuit 8 calculates the difference between the maximum value (Max) and the minimum value (Min) from the normalized line density, and uses this value as a predetermined reference value (S
_L ). That is, when Max-Min <S _L is good, when Max-Min ≧ S _L is good, Max-M
When in ≧ S _L , it is determined to be defective and the result is output (above, S5 in FIG. 2).

As described above, the linear blurring defect in the print can be detected. At this time, since the print dot center of the pattern to be inspected is indicated by the dictionary pattern (density reading point instruction pattern) and the density is measured, the measurement position does not deviate from the print dot center and correct density measurement becomes possible. The influence of the difference in the density of the print edge portion of the test pattern is eliminated, and the time for the density addition processing is shortened.

In the above embodiment, the character pattern for printer printing is used to create the dictionary pattern, but at least the creation data of the recognition target may be used to create the pattern indicating the position of the density measurement. .

〔The invention's effect〕

According to the present invention, since the dictionary pattern for instructing the position of the density measurement is created using the creation data of the recognition target and the density measurement is performed using this dictionary pattern, the print edge is affected. The linear blurring defect in the print can be inspected with an appropriate density measurement value, and the processing time becomes short.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a recognition device according to the present invention, FIG. 2 is an operation flowchart according to an embodiment of the present invention, FIG. 3 is a diagram showing an inspection target pattern, and FIG. 4 is a diagram showing a density reading point designating pattern. 5 (a) to 5 (c) are diagrams for explaining an example of concentration measurement according to an embodiment of the present invention, and FIGS. 6 (a) to 6 (d) are diagrams for explaining concentration measurement in the case of arrows, and FIG. FIG. 8 is a diagram showing normal printing of a square pattern, FIG. 8 is a diagram showing linear shading defects in the square pattern, and FIG. 9 is an enlarged view of dot printing. 1 ... Dot printer, 2 ... Test pattern, 3 ... Imaging device, 4 ... Image input circuit, 5 ... Frame memory, 6 ... Pattern matching circuit, 7 ... Density measurement circuit, 8 ... Dictionary pattern ...... Dictionary creating circuit, 10 ...... Character generator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Tsukahara, Inventor Hiroyuki Tsukahara, 1015 Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Takuya Uzumaki, 1015, Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited

Claims (3)

[Claims] 1. An image pickup device (3) for inputting an image of the recognition target with a print pattern printed by a dot printer as a recognition target, and an analog image signal output from the image pickup device (3) as a digital image signal. An image input circuit (4) for converting into a frame, a frame memory (5) for storing a digital image signal output from the image input circuit (4), and each print of the print pattern based on the print pattern creation data. A dictionary creation circuit (9) that creates a pattern that designates the center of the dot as a density measurement position as a dictionary pattern (8), and positions the image in the frame memory (5) using the dictionary pattern (8). A pattern matching circuit (6) for performing image density measurement on the positioned image at a density measurement position according to the dictionary pattern (8).
A density measuring circuit (7) that determines a defect when there is a linearly low image density portion along the scanning direction of the print head.
And a print pattern recognition device. 2. The print pattern creation data is pattern data of a character generator (10) for printing a dot printer.
A print pattern recognition device according to the item. 3. The print pattern recognition device according to claim 2, wherein the dictionary pattern (8) is formed by removing a print peripheral portion where the density value is unstable.