CN110065309B - Multi-nozzle adjusting method for overprinting - Google Patents

Abstract

The invention belongs to the field of digital printing, and particularly relates to a multi-nozzle adjusting method for overprinting. A method of multi-nozzle adjustment for overprinting, comprising the steps of: (1) a coarse adjustment stage: printing a calibration and test chart, calculating the actual distance between adjacent nozzles through the calibration and test chart, and inputting the actual distance into a jet printing system for preliminary parameter correction; 2. fine adjustment stage: and printing a fine adjustment test chart, and inputting the fine adjustment test chart into a jet printing system through the calculated deviation for further parameter correction. The invention discloses a multi-nozzle adjusting method for overprinting, which has the following beneficial effects: 1. the automation degree is high: the front and back splicing effect and parameters of the spray head are directly spliced by equipment without manual adjustment, so that the labor is reduced; 2. the quick adjustment reduces the time of machine adjustment and preparation.

Description

A multi-nozzle adjustment method for overprinting

technical field

The invention belongs to the field of digital printing, in particular to a multi-jet adjustment method for overprinting.

Background technique

Overprinting refers to the overlapping registration of graphic and text printing of various color plates during multi-color printing, that is, monochrome printing plates with different screen line angles obtained after color separation of the original, overlapping and registering in sequence according to the color order of the printing plates, and the final printing result is the same as that of the original. Prints with the same level and tone of the original. However, on the existing digital printing lines, the distance between adjacent nozzles is mostly determined by the human eye, which not only requires a lot of manual adjustment and consumes a lot of time, but also relies heavily on the experience of workers, which is not conducive to standardized production.

SUMMARY OF THE INVENTION

Object of the invention: The present invention makes improvements to the problems existing in the above-mentioned prior art, that is, the present invention discloses a multi-nozzle adjustment method for overprinting. The invention uses the test pattern sprayed on the substrate, and the machine vision system judges the test pattern, detects the relative distance, and converts the distance from pixels to actual distance and inputs it into the spray printing system for rapid adjustment and determination.

Technical solution: a multi-nozzle adjustment method for overprinting, comprising the following steps:

(1) Coarse adjustment stage

Print the calibration and test chart, calculate the actual distance between adjacent nozzles through the calibration and test chart, and input it into the printing system for preliminary parameter correction. Step (1) includes the following steps:

(11), print calibration and test chart;

(12), collecting the images of the calibration and test charts jetted in step (11);

(13), analyze the image collected in step (12):

(131) Determine the correspondence Fy between physical distances/pixels

The physical distance between the two adjacent calibration lines of the calibration and test charts is constant, set as Yd, and the template matching algorithm is used to measure the distance between the two adjacent calibration lines of the calibration and test charts. Pixel pitch Yp, then: Fy=Yd/Yp;

(132) by template matching algorithm, calculate the pixel coordinate position Yn of the scale line of the nozzle N along the paper direction, and the pixel coordinate position Yn' of the corresponding scale line of the adjacent nozzle N+f;

(133) Calculate the pixel difference: ΔY=Yn-Yn'

(134) Convert the pixel difference value ΔY into the actual physical distance difference value ΔYd, that is, ΔYd=ΔY*Fy;

(14), output the corresponding relationship between the pixel difference value ΔY obtained in step (134) and the actual physical distance difference value ΔYd to the printing system, and perform rough adjustment and correction;

2. Fine tuning stage

The fine adjustment test chart is printed, and the calculated deviation is input into the jet printing system for further parameter correction, wherein step (2) includes the following steps:

(21), print fine adjustment test chart;

(22), the image of the fine-tuning test chart obtained in the acquisition step (21);

(23), analyze the image of the fine-tuning test chart collected in step (22):

(231) locating the test image by using a template matching algorithm, and dividing the single-row line segments L-10 to L10 into 21 parts;

(232) By analyzing the continuity of the two line segments and the distance between the line segments of the 21 images in (231), it is determined which line has the best degree of coincidence of the line segments, wherein:

The line segment of each nozzle is divided into two parts, one part of the line segment is the calibration line segment, which is located on the left side of the fine adjustment test chart, and the other part of the line segment is a split line segment, and the pixel deviation from the calibration line segment is -10 to 10 pixels longitudinally. ;

(233) Obtain the line segment line number Ln with the best degree of coincidence, and convert it into the corresponding pixel deviation n, where -10≤n≤10;

(244) Return the pixel deviation n to the printing system to determine whether n is equal to 0. If it is not equal to 0, the printing system performs fine adjustment and correction, and then goes to step (21); if it is equal to 0, the use of Multi-jet adjustment for overprinting.

Beneficial effects: The multi-nozzle adjustment method for overprinting disclosed by the present invention has the following beneficial effects:

1. High degree of automation: no manual adjustment is required, the effect and parameters of the front and rear nozzles are directly assembled by the equipment, reducing labor;

2. Quick adjustment, reducing the time for machine adjustment and preparation.

Description of drawings

Fig. 1 is a flow chart of a multi-nozzle adjustment method for overprinting disclosed in the present invention;

Fig. 2 is the schematic diagram of calibration and test chart;

Fig. 3 is a schematic diagram of a fine adjustment test chart, wherein the vertical line on the right side represents the marking line of the longitudinal position of the nozzle.

Detailed ways:

The specific embodiments of the present invention will be described in detail below.

As shown in Figure 1, a method for adjusting multiple nozzles for overprinting includes the following steps:

(1) Coarse adjustment stage

Print the calibration and test chart, calculate the actual distance between adjacent nozzles through the calibration and test chart, and input it into the printing system for preliminary parameter correction. Step (1) includes the following steps:

(11), print calibration and test chart (as shown in Figure 2);

(12), collecting the images of the calibration and test charts jetted in step (11);

(13), analyze the image collected in step (12):

(131) Determine the correspondence Fy between physical distances/pixels

The physical distance between the two adjacent calibration lines of the calibration and test charts is constant, set as Yd, and the template matching algorithm is used to measure the distance between the two adjacent calibration lines of the calibration and test charts. Pixel pitch Yp, then: Fy=Yd/Yp;

(132) by template matching algorithm, calculate the pixel coordinate position Yn of the scale line of the nozzle N along the paper direction, and the pixel coordinate position Yn' of the corresponding scale line of the adjacent nozzle N+f;

(133) Calculate the pixel difference: ΔY=Yn-Yn'

(134) Convert the pixel difference value ΔY into the actual physical distance difference value ΔYd, that is, ΔYd=ΔY*Fy;

(14), output the corresponding relationship between the pixel difference value ΔY obtained in step (134) and the actual physical distance difference value ΔYd to the printing system, and perform rough adjustment and correction;

2. Fine tuning stage

The fine adjustment test chart is printed, and the calculated deviation is input into the jet printing system for further parameter correction, wherein step (2) includes the following steps:

(21), print fine adjustment test chart (as shown in Figure 3);

(22), the image of the fine-tuning test chart obtained in the acquisition step (21);

(23), analyze the image of the fine-tuning test chart collected in step (22):

(231) locating the test image through a template matching algorithm, and dividing the single-row line segments L-10 to L10 into 21 parts;

(232) By analyzing the continuity of the two line segments and the distance between the line segments of the 21 images in (231), it is determined which line has the best degree of coincidence of the line segments, wherein:

The line segment of each nozzle is divided into two parts, one part of the line segment is the calibration line segment, which is located on the left side of the fine adjustment test chart, and the other part of the line segment is a split line segment, and the pixel deviation from the calibration line segment is -10 to 10 pixels longitudinally. ;

(233) Obtain the line segment line number Ln with the best degree of coincidence, and convert it into the corresponding pixel deviation n, where -10≤n≤10;

(244) Return the pixel deviation n to the printing system to determine whether n is equal to 0. If it is not equal to 0, the printing system performs fine adjustment and correction, and then goes to step (21); if it is equal to 0, the use of Multi-jet adjustment for overprinting.

The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-mentioned embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims (1)

1. A multi-nozzle adjusting method for overprinting is characterized by comprising the following steps:

(1) coarse adjustment stage

Printing a calibration and test chart, calculating the actual distance between adjacent spray heads through the calibration and test chart, and inputting the actual distance into a spray printing system for preliminary parameter correction, wherein the step (1) comprises the following steps:

(11) jet printing calibration and test chart;

(12) collecting the calibration and test chart images of the jet printing in the step (11);

(13) and (3) analyzing the image acquired in the step (12):

(131) determining a correspondence Fy between physical distances/pixels

And the physical distance between two adjacent calibration lines of the calibration and test chart is constant and is set as Yd, and the pixel pitch Yp between two adjacent calibration lines of the calibration and test chart is measured through a template matching algorithm, then: Yd/Yp;

(132) calculating a pixel coordinate position Yn of the marking line of the spray head N along the paper moving direction and a pixel coordinate position Yn' of the corresponding marking line of the adjacent spray head N + f by a template matching algorithm;

(133) calculating a pixel difference value: delta Y-Yn'

(134) Converting the pixel difference Δ Y into an actual physical distance difference Δ Yd, i.e., Δ Yd ═ Δ Y × Fy;

(14) outputting the corresponding relation between the pixel difference value delta Y obtained in the step (134) and the actual physical distance difference value delta Yd to a jet printing system, and performing coarse adjustment and correction;

(2) fine adjustment stage

Printing a fine adjustment test chart, and inputting the fine adjustment test chart into a jet printing system through the calculated deviation for further parameter correction, wherein the step (2) comprises the following steps:

(21) spraying and printing a fine adjustment test chart;

(22) acquiring the image of the fine adjustment test chart obtained in the step (21);

(23) and analyzing the image of the fine adjustment test chart acquired in the step (22):

(231) positioning the test image by a template matching algorithm, and cutting the single-line segments L-10-L10 into 21 parts;

(232) and (231) analyzing the continuity of the two line segments of the 21 images and the distance between the line segments to determine which line has the best line segment overlap ratio, wherein:

the line segment of each spray head is divided into two parts, one part of the line segment is a calibration line segment and is positioned on the left side of the fine adjustment test chart, the other part of the line segment is a splicing line segment, and the pixel deviation of the line segment and the calibration line segment is-10 pixels longitudinally in sequence;

(233) acquiring a line segment line number L n with the best coincidence degree, and converting the line segment line number L n into a corresponding pixel deviation n, wherein n is more than or equal to-10 and less than or equal to 10;

(244) returning the pixel deviation n to the jet printing system, judging whether n is equal to 0, if not, finely adjusting and correcting the jet printing system, and then, turning to the step (21); if equal to 0, the multi-nozzle adjustment for overprinting is completed.

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