JPH09325013A - Print misregistration detection device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] From a multi-valued image of a corrugated cardboard conveyed by a mass production conveyor or the like captured by a camera 1, A / D converted, and stored in an image memory 3, a plurality of eye marks on a corrugated cardboard are distinguished. This eliminates the need for complicated window settings for the device that detects the misalignment of printing due to key operations when changing the type of corrugated board. SOLUTION: A corrugated cardboard paper (sample paper) that is correctly printed in advance (with an eye mark at a reference position) is prepared, and a sample paper input command 21 is given to the device, and a binarization circuit 5 and change point extraction are performed. The circuit 9, the change point memory 10, the CPU 13, etc. detect the coordinates of the eye mark on the corrugated paper from the differential binarized image of the eye mark, and the RAM 14 as the reference coordinates.
Is stored. Next, when the corrugated paper to be inspected is conveyed and reaches the image pickup position of the camera, the determination start command 22 is input to the apparatus and the eye mark coordinates are detected in the same manner as the sample paper,
The pass / fail judgment result 23 is output depending on whether the difference between the detected coordinate and the reference coordinate is within the allowable value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object such as corrugated paper which is printed on one or a plurality of printing areas in which the position of the printing area is specified by a positioning mark and is conveyed by a mass production conveyor or the like. The present invention relates to a print misregistration detection apparatus as an image processing apparatus that picks up an image using a two-dimensional image pickup apparatus, and determines the quality of the position of a print area on an object from a digital image obtained by A / D converting the image.

[0002] In the drawings, the same reference numerals indicate the same or corresponding parts.

[0003]

2. Description of the Related Art Conventionally, in an image processing apparatus for detecting this kind of print position deviation, a sample object printed in advance at a correct position in order to set a reference position of a positioning mark on the object. The image is captured, the window is set to the position of each positioning mark on this image by key input, and the reference coordinates of the positioning mark are detected in the set window.

[0004]

However, in the above-mentioned conventional image processing apparatus, whenever the kind of the object changes, the setting corresponding to the kind must be manually performed each time. Preparations in advance were complicated. In addition, when there are a plurality of positioning marks on one screen, it is necessary to give a command for each detection location and switch the settings to make a determination, which causes a problem that the processing takes time.

Therefore, it is an object of the present invention to provide a print misregistration detection device that can solve such problems.

[0006]

In order to solve the above-mentioned problems, the printing misregistration detection device according to claim 1 specifies the position of the printing area by the corresponding positioning marks (eye marks 02A to 02C, etc.). Alternatively, an object (corrugated cardboard, etc.) printed on a plurality of printing areas is imaged using a two-dimensional imaging device (camera 1), and the image is A / D converted (via an A / D converter 2). (Then, stored in the image memory 3)
In a device for detecting the positional deviation of the print area on the object from the digital image obtained by the above, the object of the sample (sample paper based on the position of each print area in advance (based on the sample paper input command 21) is used). Position of each positioning mark on the sample object (reference coordinate X _SA ,
Means (RAM1) for detecting and storing X _SB , X _SC, etc.
4), detecting the position (detection coordinates X _DA , X _DB , X _DC, etc.) of each positioning mark on this object from the digital image of the object to be inspected (based on the determination start command 22),
Deviation amount (X _SA -X _DA between the position of the positioning marks respectively corresponding on the object of the stored samples of the the position of the positioning marks this _{detection, X SB -X DB, X SC} -X DC etc. ) Is compared with the corresponding permissible values (± ΔX, etc.) set in advance, and the quality of the printing position is judged (the judgment result 23
Output means) (CPU 13).

According to a second aspect of the present invention, there is provided the printing misregistration detection device according to the first aspect, wherein the position of each of the positioning marks is the positioning mark (binarization circuit 5).
Via a binary image or a differential binary image. According to a third aspect of the present invention, in the printing misregistration detection apparatus according to the first or second aspect, the object is corrugated paper.

The operation of the present invention is as follows. That is, the sample object is imaged when the type of the object is switched, the entire position of the object is detected from this image, and the position of the frame of the preset entire area for detecting the positioning mark is detected. Correction is performed according to the overall position of the object, and the plurality of positioning marks in this frame are differentiated into binary. In the case of an embodiment described later, the differential binarized image is then projected in the horizontal direction, and the vertical position of each positioning mark is automatically detected. Then, a preset horizontal position detection window is generated in accordance with the detected vertical position of each positioning mark, and the coordinates of the right end of the positioning mark in each window are detected and stored as reference coordinates.

At the time of determining the inspection object, the coordinates of the right end of the positioning mark in each window are detected and the amount of deviation from the reference coordinates is calculated, as in the case of the sample object. Then, it is determined whether or not this deviation amount is within a preset allowable value, and a pass / fail signal is output.

[0010]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing the arrangement of a print misregistration detection apparatus as an embodiment of the present invention.
In FIG. 1, reference numeral 1 is a TV camera as a two-dimensional image pickup device for picking up an image of a printed surface of corrugated cardboard paper (also simply referred to as corrugated board) as an object conveyed by a mass production conveyor (not shown), and 2 is a camera 1 An A / D converter 3 for converting a video signal output by raster scanning of a picked-up image into multivalued grayscale image data is an image memory for storing this image data as a multivalued grayscale image corresponding to the picked-up image. .

Next, 11 is a window memory for storing a preset window pattern (a whole area frame 05, windows 06A to 06C, etc., which will be described later) which defines a mask area (window area) of the image data of the image memory 3. Four
Is an image memory control circuit that sets a window area fetched from the window memory 11 at a designated position, and controls to fetch the image data of this window area from the image memory 3, and the image memory control circuit 5 controls the image data fetched from the image memory 3. It is a binarization circuit for binarizing or differential binarizing.

Reference numeral 7 is a projection extraction circuit for extracting the projection data of the binarized image output from the binarization circuit 5, 8 is a projection memory for storing the projection data extracted by the projection extraction circuit 7, and 9 is 2 A change point extraction circuit 10 for extracting the change points of the rising and falling edges of the differential binarized image output from the binarization circuit 5 is a change point memory for storing the extracted change point data.

Reference numeral 12 is an input / output interface circuit with the outside of the apparatus, 13 is a microprocessor (hereinafter abbreviated as CPU) for controlling the entire apparatus, and 14 is a CPU.
RAM as working memory 13 and CPU 1
3, a bus for connecting the RAM 14, the projection memory 8, the change point memory 10, the window memory 11, the input / output interface circuit 12, and the like.

Next, reference numeral 21 is a sample paper input command given to the CPU 13 from the outside through the input / output interface circuit 12, and the image of the sample paper as a corrugated paper of the sample printed at the reference position should be inputted. Command to the effect, 2
Reference numeral 2 is a determination start command externally given to the CPU 13 when the corrugated cardboard to be inspected is conveyed to the imaging position of the camera 1, and is a process for inputting an image of the corrugated cardboard to be inspected and determining whether the printing position is good or bad. Is a command to start. Reference numeral 23 is a quality determination result output from the CPU 13 via the input / output interface circuit 12 to the outside.

FIG. 2 is a screen view for explaining a coordinate detecting operation of a positioning mark (called an eye mark) of an object as an embodiment of the present invention. In this example, three eye marks are shown. In the figure, F is an input screen of the printing surface of the corrugated cardboard as an object, 01 is the left end (corrugated cardboard end) of the corrugated cardboard which is the reference of the horizontal position of the corrugated cardboard, and 02 (02A, 02B, 02C) Three eye marks, namely, the upper, middle, and lower eye marks, as printing positioning marks provided on the left end side of this corrugated paper, 03
Is a differential binarized image showing the contour of each eye mark 02.

Reference numeral 04 denotes an intersection between the corrugated board edge 01 and a horizontal line in contact with the lower edge of the lower eye mark 02C. In this embodiment, it represents the position of the object and is called the overall position detection point. 05
Is a rectangular frame with a preset size, which is placed so that the overall position detection point 04 is the lower left corner point, and is called the overall region frame. Also 0
6 (06A, 06B, 06C) is a window as a detection area of the position (in this case, the coordinate of the right end) of the eye mark 02 (02A, 02B, 02C) of the corrugated paper to be inspected.

FIG. 3 is a flowchart for detecting the coordinates of the eye mark on the sample paper, and S1 to S10 show the steps. Next, the operation of FIG. 1 will be described with reference to FIGS. First, the sample paper is imaged by the camera 1 in synchronization with the sample paper input command 21 input to the input / output interface circuit 12 from the outside, and the imaged image is digitized by the A / D converter 2, A multi-value grayscale image composed of image data is input to the image memory 3 (S1). Then, the image in the image memory 3 is binarized by a predetermined threshold value through the binarization circuit 5, and the projection and extraction circuit 7 obtains the projections of the binarized image in the horizontal and vertical directions. Are stored in the projection memory 8.

From the projection data of the projection memory 8 to the CPU
The coordinates of the overall position detection point 04 determined by the horizontal coordinates of the cardboard edge 01 and the vertical coordinates of the lower edge of the lower eye mark 02C as shown in FIG. The positional shift amount of the entire area frame 05 is detected (S2). Then, the whole area frame 05 preset so as to surround the three eye marks 02A to 02C is read out from the window memory 11, and the whole lower area corner point of the whole area frame 05 is made to coincide with the whole position detection point 04. After correcting the positional deviation amount of the frame 05, the entire area frame 05 is set in the image memory control circuit 4 (S
3).

Then, the image in the entire area frame 05 is read from the image memory 3 via the image memory control circuit 4, and is binarized by the binarizing circuit 5 (that is, the density gradient of each target point is set to a predetermined threshold value). The value is binarized) (S4). Then, the change point is detected from the differential binarized image via the change point extraction circuit 9 and stored in the change point memory 10. Next, from the stored change point data of each eye mark 02A to 02C, the CP
Horizontal projection data 07 of the differential binarized image of each eye mark 02A to 02C is created by the software processing of U13 (S5), and each eye mark 0 is based on this projection data 07.
2A, 02B, the vertical position of the upper and lower ends of each of _{02C (Y UA, Y LA,} Y UB, Y LB, Y UC, Y LC) to detect the following formula each eye mark 02A~02C by ~ The respective center coordinates (Y _CA , Y _CB , Y _CC ) in the vertical direction of are calculated (S6).

[0020]

[Formula 1] Y _CA = (Y _UA −Y _LA ) / 2 + Y _LA・ ・ ・ Y _CB = (Y _UB −Y _LB ) / 2 + Y _LB・ ・ ・ Y _CC = (Y _UC −Y _LC ) / 2 + Y _LC · .. Next, the windows 06 (06A to 06) as preset areas for horizontal position detection of each eye mark 02 are detected.
C) is called from the window memory 11, and the windows 06A to 06C are displayed in the vertical direction.
The centers of A to 06C correspond to the center coordinates (Y _CA , Y _CB , and Y _CC ) obtained by the above equations, respectively, and in the horizontal direction, the right ends of the eye marks 02A to 02C respectively correspond to the windows 06A to. After correcting the positional deviation of each of the windows 06A to 06C so as to occur at a predetermined position that is sufficiently contained in 06C, the windows 06A to 06C are set in the image memory control circuit 4 (S7).

Then, the image in each of the windows 06A to 06C is read from the image memory 3 via the image memory control circuit 4, the read image is binarized by the binarization circuit 5, and from this differential binarized image. The change point in the horizontal direction of each of the eye marks 02A to 02C (the right end of the eye mark) is detected via the change point extraction circuit 9, and the detected change point data is stored in the change point memory 10 (S8).

From this stored change point data, the CP
U13 by the right end of the horizontal coordinate X _S of each eye mark _{02A~02C (X SA, X SB,} X SC) the calculated (S9),
This coordinate X _S (X _SA , X _SB , X _SC ) is _assigned to each eye mark 02.
It is stored in the RAM 14 as the reference coordinates of A to 02C (S
10), and the process of FIG. 3 ends. FIG. 4 is a flow chart of the quality judgment operation for the corrugated cardboard to be inspected.
S13 shows the step. This figure is different from FIG. 3 in that steps S1, S9, and S10 are S1A, S9A, and S10A, respectively.
Is replaced with steps S11 to S13.

Next, referring mainly to FIGS. 2 and 4, mainly in FIG.
The operation of FIG. 1 different from that of FIG. Inspection target
Whether the roll paper has arrived at the imaging position of camera 1
In synchronization with the judgment start command 22 from
Capture the image from camera 1 (S1A), same as the case of sample paper
Similarly, the CPU 13 causes each of the eye marks 02A to 02C
Horizontal coordinate X of the right edge_D(X_DA, X_DB, X_DC)
(S2 to S9A). And each detection coordinate (X_DA, X
_DB, X_DC) And the reference coordinates (X_SA, X _SB, X
_SC) And the corresponding shift amount (X_SA-X_DA, X_SB−
X_DB, X_SC-X_DC) Is calculated (S10A) and preset
Compared with the allowable value (± ΔX) (S11), this deviation amount
Is a non-defective product if is within the allowable value as in the following equations
Then, the determination result 23 as a non-defective signal is output to the outside.
(S12).

[0024]

-ΔX ≤ X _SA -X _DA ≤ + ΔX ... -ΔX ≤ X _SB -X _DB ≤ + ΔX ... -ΔX ≤ X _SC -X _DC ≤ + ΔX ... On the other hand, comparison of the step S11 Then, eye mark 02A
If the amount of deviation of the detected coordinates of any of the above-mentioned 02C is out of the allowable value as in the following equations, it is determined to be defective, and the determination result 23 as a defective signal is output to the outside (S13).

[0025]

X _SA −X _DA ≦ −ΔX or + ΔX ≦ X _SA −X _DA ... X _SB −X _DB ≦ −ΔX or + ΔX ≦ X _SB −X _DB・ ・ ・ X _SC −X _DC ≦ −ΔX or + ΔX ≦ X _SC -X _DC ··· Note tolerance (± [Delta] X) can be freely set.

[0026]

According to the present invention, a sample paper is prepared in advance,
By giving a sample paper input command, the device inputs the image of the sample paper and automatically detects and sets the reference coordinates of the eye mark 02. No setting operation is required.

Further, the shift amounts of a plurality of eye marks can be simultaneously judged by one image input by one command, and the processing time can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an apparatus as an embodiment of the present invention.

FIG. 2 is a screen diagram for explaining the eye mark coordinate detection operation.

FIG. 3 is a flowchart of the coordinate detection operation of the eye mark of the sample corrugated cardboard.

FIG. 4 is a flow chart of a quality judgment operation of the corrugated paper that is also the inspection target

[Explanation of Codes] F Screen 01 Cardboard Edge 02 (02A-02C) Eye Mark 03 Differential Binary Image 04 Whole Position Detection Point 05 Whole Area Frame 06 (06A to 06C) Window 07 Projection Data 1 Camera 2 A / D Conversion 3 Image memory 4 Image memory control circuit 5 Binarization circuit 7 Projection extraction circuit 8 Projection memory 9 Change point extraction circuit 10 Change point memory 11 Window memory 12 Input / output interface circuit 13 Microprocessor (CPU) 14 RAM 15 Bus 21 views Paper input command 22 Judgment start command 23 Judgment result

Claims (3)

[Claims] 1. A two-dimensional image pickup device picks up an image of an object printed in one or a plurality of printing areas in which the positions of the printing areas are specified by corresponding positioning marks, and the image is A / D. In a device that detects the positional deviation of the print area on the object from the digital image obtained by conversion, each positioning mark on the sample object from the digital image of the sample object whose position is the reference in advance. Means for detecting and storing the position of each of the positioning marks on the object from the digital image of the object to be inspected, and the position of each of the detected positioning marks and the object of the stored sample. A printing shift comprising means for comparing the amount of deviation of the position of each corresponding positioning mark on the object with a corresponding corresponding preset value, and determining the quality of the printing position. Detection device. 2. The printing misregistration detection device according to claim 1, wherein the position of each of the positioning marks is 2 of the positioning mark.
A printing misregistration detection device, which is obtained from a binarized image or a differential binarized image. 3. The printing misregistration detection device according to claim 1, wherein the object is a corrugated cardboard paper.