JPH07290693A - Registration regulating controller for multi-color printer - Google Patents

Abstract

PURPOSE:To directly detect a registering deviation from a halftone dot of an arbitrary design without providing a registering special mark on a printing plate by providing registering controller means for applying a correction signal of a deviation to a driver of an edition of the design by registration generating means. CONSTITUTION:A camera is moved to a position where a halftone of a process color of a printed matter to be imaged on a sheet set on a base in the case 1a of setting a camera position. In the case 1b of imaging, imaging (correcting the camera position) is executed until it is obtained as a predetermined output value of the halftone of used ink, i.e., as a digital signal. In the case 2a of four process colors, when an output value for deciding the camera position is decided, four colors (black, indigo blue, red, and yellow) are confirmed. In the case of 'NO', it is returned to the case 1a of setting the camera position. In the case 2b of (R plane, G plane, B plane), measurable states of the planes are confirmed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a register adjustment control device for a multicolor printing machine for registering a multicolor printing machine.

[0002]

2. Description of the Related Art Conventionally, the registration of a multi-color printing machine is performed manually, and a person judges the misregistration to operate the registration control device of the printing machine. A normal multicolor printing machine prints four colors of process inks by printing them in a superimposed manner, but the registration requires high precision, and this registration work puts a heavy burden on the operator. ing.
Therefore, various automatic register adjustment devices have been proposed,
Among them, what is mainly carried out is a device for attaching registration marks, diamond marks, etc. for registration on a printing plate, and for adjusting the misregistration for detecting the position of the marks by a simple optical means. . Further, there is also proposed a register adjusting device that does not require a register mark and uses halftone dot edges of a pattern.

[0003]

However, in such an apparatus, since a special mark for optical reading is put in a printed matter, there is a problem that a blank space is wasted, and a trouble of putting the special mark occurs. In the inspection of the special mark, the periphery of the printed matter is inspected, and there is a problem that the pattern portion cannot be accurately registered when the printed matter contracts due to humidity or the like. Further, even in the register adjustment control device that does not require a special mark, the reading position is limited.
The present invention was devised in view of the above-mentioned points, and the purpose thereof is to directly add arbitrary marks by using advanced image processing technology without putting special marks for registration on the printing plate. A register adjustment control device for a multi-color printing machine is provided which detects register misregistration from the halftone dots of the image and gives register adjustment information such as top / bottom left / right and twist to an appropriate register adjustment controller.

[0004]

[Means for Solving the Problems] That is, means for achieving the object are reading means for color-enlarged imaging of a pattern on a printed matter and reading halftone dots as RGB luminance signals by a camera, and the read RGB luminance signals. Noise removal means for removing the noise of the
The binarizing means for binarizing, the extracting means for dividing and extracting the reference color and the other colors from the binarized RGB luminance signal into the respective image processing memories (planes) as color halftone dot figures, and the dividing and extracting. A center of gravity calculating means for calculating the center of gravity of a halftone dot figure, a relative distance calculating means for calculating a relative distance of X and Y coordinates from a center of gravity of a reference color to a center of gravity of multiple colors, and a reference value registration for registering this as a reference value. Means and a comparing means for comparing the relative distance of the center of gravity of the halftone dots of the next pattern with the reference value after this reference registration, and when a difference is caused by the comparing means, the difference is corrected. A register defect generating means for generating a register control signal and a register control device means for giving a correction signal of the deviation amount to a drive device of a picture pattern by the register generating means.

[0005]

In general, the pattern is a superposition of process inks, and the pattern is composed of a set of dots for each ink. Further, the halftone dots of the pattern are perceived as RGB luminance reduction information for the white part due to the complementary color relationship when magnified and imaged by the CCD color camera.
It can be decomposed into each plane and extracted as halftone dot figures such as indigo, red, and yellow. Further, the center of gravity of the halftone dots of each plane can be obtained, and the relative distance of the center of gravity from the other plane can be obtained with reference to the reference color, for example, the center of gravity of the black halftone dots. However, the center of gravity of the reference color is registered in advance. FIG. 3 is an example in which the extracted halftone dot figures are superimposed and displayed on the four planes of black, indigo, red, and yellow to explain the relative distance. The relative distance is measured on a registered printed matter and stored as a reference. It shows that the relative distance of the printed matter to be measured is measured, and if the difference between the relative distance and the reference value is more than a certain value, it can be judged as misregistration. Distance A between each color based on black dots
The lateral misregistration can be detected by the relative fluctuations of B and C, and the misregistration due to the relative fluctuations of the vertical distances D, E, and F can be detected. Also, the opposite may be the case. When there are two cameras, twist register control becomes possible due to the relative fluctuations of the vertical distances D, E, and F with respect to the black dots in the other camera. Thus, in the present invention,
By extracting halftone dot patterns on the four planes of black, indigo, red and yellow with a single color CCD camera, the center of gravity shift between the planes will be eliminated, and the distance will be calculated based on the relative position. The effect is eliminated, specific halftone dots can be extracted by advanced image processing, and for the above reasons, it is possible to directly obtain the registration signal from the picture without adding a special registration mark as in the past. Become. An embodiment of the present invention will be described in detail below with reference to the drawings.

[0006]

FIG. 1 is a block diagram showing an embodiment of the present invention. In the present apparatus, a reading means for color-enlarged image of a printed matter to read halftone dots as RGB luminance signals by a camera, a noise removing means for removing noise of the read RGB luminance signals, and a noise-removed RGB luminance signal. Binarizing means for binarizing, the extracting means for dividing and extracting the reference color and other colors from the binarized RGB luminance signal into respective image processing memories (planes) as halftone dot patterns by color, and this division. A center of gravity calculating means for calculating the center of gravity of the extracted halftone dot figure, a relative distance calculating means for calculating the relative distance of the X and Y coordinates from the center of gravity of the reference color to the center of gravity of multiple colors, and a reference for registering this as a reference value. The value registration means, the comparison means for comparing the relative distance of the center of gravity of the halftone dots of the next picture after the reference registration with the reference value, and the difference when the comparison means causes the difference. A registration failure generation means for generating a register control signal for the correction of, in which a structure and a register controller means for providing a correction signal of the shift amount to the driving unit of a picture of determine by the register generator. Figure 1
In, at the color enlarged image of the design of the printed matter,
The reading means for reading with the camera as a GB luminance signal is performed by the illuminated image pickup device 1 having a CCD color camera having a magnification capable of picking up halftone dots. This read R
Noise removing means for removing noise from the GB luminance signal, binarizing means for binarizing the RGB luminance signal from which noise has been removed, and image processing memories for the reference color and other colors from the binarized RGB luminance signal. Extraction means for dividing and extracting color halftone dot graphics on a (plane), center of gravity calculating means for calculating the center of gravity of the divided and extracted halftone dot figures, and X, Y coordinates from the center of gravity of the reference color to the center of gravity of multiple colors. A reference value registration means for reading the relative distance and using this as a reference value; and a comparison means for comparing the relative distance of the center of gravity of the halftone dots of the next pattern after the reference registration with the reference value. When a difference is generated by the comparison means, the registration defect generating means for generating a registration control signal for correcting the difference is an image processing for processing a RGB luminance signal from the illuminated image pickup device 1 to extract a halftone image. Done on device 2 In the image processing device 2, when there is a deviation amount, the correction command is issued by the register control device 4.
Further, the misregistration is displayed on the monitor device 3.

The components of these block diagrams are explanatory views of the register adjustment control device of FIG. 2, and the CCD camera 1 is used as the illuminated image pickup device 1. This CCD camera 1 uses a three-plate CCD color camera, but any CCD color camera capable of detecting RGB luminance values with good precision may be used, and a halogen light source is provided in order to reduce influence on external light. Further, a telephoto lens of about 200 times is used to obtain a halftone image. This configuration is intended for vertical, horizontal, and twist register control.
Although two cameras are used to capture images at two locations, one image is sufficient for up / down / left / right registration control. Also,
There is a difference in accuracy even when performing twist registration, but 1 unit is 1
It is possible to pick up a plurality of halftone dots by picking up an image of a part, and one CCD camera may pick up an image of two parts. Further, the CCD camera 1 is attached to a support frame 6 fixed to a base 5 and fixed at a camera position for picking up an image of a specific pattern portion. This setting method is arbitrary, but it is necessary to include the halftone dots of the ink used in the image pickup portion, and the device structure is such that the monitor device can move while looking at the halftone dots of the pattern. If the camera position is set, a certain pattern portion can be extracted even if the printed matter to be inspected changes by coming into contact with the stopper 7 provided at a predetermined position on the table 5. Since the misregistration is judged based on the relative position between the halftone dots that are simultaneously picked up by the color camera, even this kind of sheet alignment can be sufficiently dealt with. The image processing device 2 includes the noise removing means described above,
The binarizing means, the extracting means, the center of gravity calculating means, the reference value registering means, the comparing means, and the misregistration generating means are housed.

Next, these functions and their functions will be described with reference to the flow chart shown in FIG. In the camera position setting 1a, the camera is moved to a position where a halftone dot of the process color of the printed matter to be imaged on the paper set on the table 5 is obtained. In the imaging 1b, imaging (correction of camera position) is performed until a predetermined output value of the halftone dot of the ink used, that is, a digital signal is obtained. When the camera position is determined and the output value is determined in the process with four colors 2a, confirmation of four colors (black, indigo, red, and yellow) is performed, and in the case of "NO", the process returns to the camera position setting 1a. In (R plane, G plane, B plane) 2b, the measurable state of each plane is confirmed. In the noise removal 2c, the obtained RGB original image is subjected to appropriate noise removal in order to remove the influence of shading or the like of the CCD camera 1. Specifically, by applying a K median filter or the like, which is a general theory of image processing, it becomes possible to accurately grasp the halftone dot shape. Binarization 2d The imaged image can be regarded as a decrease in RGB brightness with respect to the white part of the printed matter due to the complementary color relationship of the process ink. If an optimum threshold value is set, a binary dot pattern for each RGB brightness is set. Can be extracted. Since the threshold to be set needs to suppress the binarization fluctuation due to disturbance, the automatic threshold setting method that allows immediate resetting when the fluctuation occurs is adopted. Although various threshold setting methods have been established as a general theory of image processing, the p-tile method is adopted because the halftone dot shape of the image to be extracted is close to an ellipse and the area is constant. In addition, regarding black ink extraction, since it is a portion where the three primary colors overlap, a logical operation 2e is performed for extraction.

Extraction 2f of 4 Colors When the binarization of the elliptical halftone dot or the lacking elliptical halftone dot is completed as described above, the R luminance signal is next colored in the indigo halftone plane G due to the complementary color relationship. The red dot plane can be extracted as the luminance signal, and the yellow dot plane can be extracted as the B luminance signal. The black dot plane is extracted as a logical product of RGB luminance signals. Here, it is difficult to separate a portion where the black halftone dots and other colors overlap, but the black portion is removed by exclusive OR of the planes of the black halftone dots and each color halftone dot. As a result, the extracted halftone dots do not become elliptical and the halftone dot area decreases,
There is no particular problem. That is, the processing is performed after each color other than the black color is binarized. Further, even if there are many colors to be printed, the colors can be separated by a logical operation of RGB luminance. Thus, R
From the GB luminance signal to the logical operation between planes,
The indigo, red, and yellow halftone dot patterns are extracted on four planes, but a plurality of halftone dots are extracted depending on the magnification. For the labeling 2g, when the planes of each halftone dot are extracted, only the specific halftone dots necessary for the gravity center calculation are calculated in order to calculate the gravity center from the obtained halftone dot and judge the misregistration based on the relative position. The process of erasing the unnecessary halftone dot figures remaining is performed by the labeling 2g. As a means for erasing specific halftone dots, a method of labeling by a labeling method, which is a general theory of image processing, and erasing except for those having a large area with respect to the labeled figure is adopted. By this method, it is possible to extract specific halftone dots that are not affected by noise. Regarding the center of gravity calculation 2h and the relative distance calculation 2j, the center of gravity calculation 2h and the relative distance calculation 2j of each halftone dot are performed here. The calculation of the center of gravity and the relative positional relationship will be described with reference to FIGS. 3 and 4.
The operation is omitted because it has been described above.

FIG. 3 shows a means for extracting one halftone dot in each plane and calculating the center of gravity of each halftone dot to calculate the relative position, that is, a center of gravity calculating means for calculating the center of gravity of the divided and extracted halftone dot graphic, and a reference. Reference value registration means for reading the relative distances of the X and Y coordinates from the barycenter of color to the barycenter of multiple colors and using this as a reference value is shown. FIG. 4 shows a plurality of halftone dots in the CCD camera 1. 3 shows the centroid calculating means for extracting three halftone dots and calculating the relative distance from the centroids of them to the halftone dots of other colors. Initial setting 2k, reference value registration 2m When the center of gravity and relative distance of the halftone dots of each color are determined by the above calculation, it is judged whether or not to register this.
If "NO", the first pattern is registered by the reference value registration 2m, and the image capturing 1b is provided with a signal that may capture the next pattern. In this way, the reference registration is performed for the first pattern with the black dots as the reference, but the barycenters of the dots and the relative distance from the barycenters may be calculated according to the next pattern. The next pattern is input to the initialized 2k through each process in the same way as described above, and it is judged "YES" whether the previous pattern and the current pattern can be compared.
Then, proceed to the next program. For comparison 2n, a comparison of the relative distances of each color is now made, as described in the action section. As an example, FIG. 6 shows the misregistration amount. It can be seen from FIG. 6 that the yellow halftone dot based on the black halftone dot has a shift amount of +5 dots in the X direction and +5 dots in the Y direction. It is judged whether or not there is a register shift amount in the register defect occurrence 2p, the monitor device 3, and the register control device 4, and if "NO" is judged, a signal for starting the image pickup of the next pattern is given. In the reference value registration 2m, the next imaging start signal is only given to the imaging 1b only when the reference value is registered. When it is determined to be "YES", the register shift amount is displayed on the monitor device 3 and also transmitted to the register control device 4 for the +5 dots in each of the X and Y directions, which is not shown (not shown). A signal that shifts each pixel by -5 dots is transmitted to the drive mechanism. Also,
After a predetermined time when the correction is completed, a signal for picking up the next pattern is given to the image pickup 1b. In this way, when the difference between the relative distances is calculated and the absolute value of the difference becomes larger than the set reference value, it is detected as a misregistration, and the deviation direction is calculated according to the size of the deviation, and the controller is twisted vertically and horizontally. The registration control signal of is continuously transmitted. Although the barycentric coordinate is represented by the number of dots, it may be converted into a machine precision unit mm by a certain coefficient. These pieces of information can be displayed on the CRT and monitored at any time, and the occurrence of misregistration can be displayed on the CRT to remind the operator.

[0011]

As described above, according to the present invention, since the register control signal can be generated without adding a special register control mark on the printing plate, the following effects are produced. (1) There is no need to add special marks in the platemaking department. (2) Paper is saved because the special mark is not added. (3) There is no need to delete special marks from paper. (4) The registration accuracy is improved because the registration is performed not by the special mark but by the design. (5) It is particularly effective for printed matter to which special marks cannot be added. (6) If there is a pattern in which the ink used is present, it can be measured at any place on the printed matter. Further, since it is possible to measure a portion of the design which seems to be particularly important, register control is remarkably improved. (7) Since the misregistration is judged by the relative distance between the halftone dots of the data captured by the color CCD camera at a time, the camera shake due to the vibration of the printing machine and the influence of the shake of the printed matter are eliminated. Also, the method for fixing printed matter can be simplified, and the device can be manufactured at low cost. From these things, the register adjustment control device of the multicolor printing machine, which greatly contributes to the reduction of printing cost and the improvement of printing quality, is extremely useful in practice.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of FIG. 1.

FIG. 3 is a halftone dot image diagram of black, red, indigo, and yellow, which is enlarged and picked up by an image pickup camera and extracted by image processing.

FIG. 4 shows an enlarged view of a plurality of indigo halftone dots enlarged by the imaging camera and extracted by image processing, and their centroid positions.

FIG. 5 is a flowchart that also serves as a component of the present invention.

[Explanation of symbols]

 1 Illuminated imaging device 2 Image processing device 3 Monitor device 4 Register control device 5 units 6 Support frame 7 Stopper 1b Imaging 2c Noise removal 2d Binarization 2f Four color extraction 2h Center of gravity calculation 2j Relative distance calculation 2m Reference value registration 2n Comparison 2p Registration error occurred

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 13, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of FIG. 1.

FIG. 3 is a halftone dot image diagram of black, red, indigo, and yellow, which is enlarged and picked up by an image pickup camera and extracted by image processing.

FIG. 4 shows an enlarged view of a plurality of indigo halftone dots enlarged by the imaging camera and extracted by image processing, and their centroid positions.

FIG. 5 is a flowchart that also serves as a component of the present invention.

FIG. 6 is an explanatory diagram of an amount of misregistration in an example of measuring a relative distance between halftone dots.

[Explanation of symbols] 1 Imager with illumination 2 Image processor 3 Monitor device 4 Register control device 5 6 Support frame 7 Stopper 1b Imaging 2c Noise removal 2d Binarization 2f 4 color extraction 2h Center of gravity calculation 2j Relative distance calculation 2m Reference value registration 2n Comparison 2p Registration error occurred

Claims (1)

[Claims] 1. A register adjusting control device of a multicolor printing machine, wherein a reading means for color-enlarged imaging of a pattern of a printed matter to read halftone dots by a camera as an RGB luminance signal, and noise of the read RGB luminance signal are removed. Noise removal means, binarization means for binarizing the RGB luminance signal from which noise has been removed, and reference colors and other colors from this binarized RGB luminance signal in respective image processing memories (planes) for each color. Extraction means for dividing and extracting as a figure, center of gravity calculating means for calculating the center of gravity of the divided and extracted halftone dot figure, and relative distance calculation for calculating the relative distance of X and Y coordinates from the center of gravity of the reference color to the center of gravity of multiple colors Means, reference value registration means for registering the reference value as a reference value, and comparison means for comparing the relative distance of the center of gravity of the halftone dots of the next picture after the reference registration with the reference value. means When a difference occurs, a register defect generating means for generating a register control signal for correcting the difference, and a register control device means for giving a correction signal for the deviation amount to the drive device of the pattern by the register generating means. A register adjustment control device for a multi-color printing press, which is characterized by having the following.