Method and device for adjusting consistency of digital printing nozzles

Abstract

The invention relates to a method and a device for adjusting the consistency of digital printing nozzles, and the method comprises the following steps: S1, preparation work: pre-printing a special correction pattern on a reference printer, calculating Lab values of color blocks with the same chromaticity at all positions of a full breadth, solving an average value, and storing the average value as SLab; s2, correction is started, and a to-be-corrected printer is used for printing a special correction pattern; s3, starting image scanning; s4, calculating Lab numerical values of all nozzle color blocks of the printer to be corrected, calculating the difference of each nozzle according to the reference value Slab, and solving delta E00; s5, nozzle calculation is performed one by one, nozzle parameters are optimized, when delta E00 reaches the minimum value, the optimal value is achieved, and related parameters are stored; and S6, outputting the adjustment coefficient of each nozzle. According to detection and correction of the method, a camera is adopted for automatic scanning and transmitting to an image processing unit, automatic processing is carried out, and adjusting parameters of all nozzles are given; the method does not depend on observation and judgment of operators, skill requirements of the operators are lowered, working efficiency is improved, and waste of printed materials is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of digital printing, and in particular to a method and a device for adjusting the consistency of a digital printing nozzle. Background Art

[0002] The width of a digital printhead is about 100mm, while large-format digital printing needs to reach more than 3m. In order to meet the needs of large-format printing, multiple printheads are spliced ​​together. There are certain differences between printheads. When printing the same color, the output will have a certain color difference. In order to ensure the overall printing quality, the parameters between printheads need to be adjusted to achieve consistency correction. The traditional method is to manually input the data into the printing system, and then the printing system will print to see if the effect is appropriate. If not, adjust again. The adjustment process is complicated and inefficient, and the human eye cannot stably and accurately interpret weak color differences. Summary of the invention

[0003] The purpose of the present invention is to provide a method for adjusting the consistency of a digital printing nozzle to solve the problems of low efficiency and low accuracy of manual detection and adjustment methods, and also to provide a device for adjusting the consistency of a digital printing nozzle for implementing the method.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for adjusting the consistency of a digital printing nozzle comprises the following steps:

[0006] S1: Preparation: pre-print the calibration pattern on the reference printer according to the standardized process, calculate the Lab value of the same chromaticity color block at each position of the full-width, calculate the average value, and save it as the reference value SLab;

[0007] S2: Start calibration, and use the printer to be calibrated to print a special calibration pattern;

[0008] S3: After printing is completed, image scanning begins;

[0009] S4: Calculate the Lab values ​​of all the color blocks of the printer to be calibrated, calculate the difference of each nozzle according to the pre-processed reference value Slab, and calculate ΔE00;

[0010] S5: Calculate each nozzle one by one, optimize the nozzle parameters, and when ΔE00 reaches the minimum, the optimum is reached and the relevant parameters are stored;

[0011] S6: Output the adjustment coefficient of each nozzle.

[0012] Furthermore, in step S3, the image is scanned and then transmitted to an image processor.

[0013] Furthermore, the paper conveying direction is defined as being along the left-right direction, and the image scanning direction is along the front-back direction.

[0014] Furthermore, correction plates are provided on the front and rear sides of the correction-specific pattern printed in step S2, and during the image scanning process, the image of the correction plate is also collected.

[0015] Furthermore, the correction plate is a white plate, which is used to perform white correction on the image.

[0016] Furthermore, in step S3, a line array camera is used to perform image scanning.

[0017] Furthermore, the illumination light source used in conjunction with the linear array camera adopts an LED constant current constant temperature light source.

[0018] A device for adjusting the consistency of a digital printing nozzle comprises at least one processor, at least one memory and computer program instructions stored in the memory, and when the computer program instructions are executed by the processor, an adjustment method as claimed in any one of claims 1 to 7 is implemented.

[0019] Beneficial effects of the present invention:

[0020] The present invention uses a camera to scan the calibration pattern printed by the printer to be calibrated, and after scanning, outputs an image or calibration coefficients of each nozzle according to customer needs. The detection and calibration of this method does not rely on the observation and judgment of the operator, reduces the skill requirements of the operator, thereby improving work efficiency, reducing waste of substrates, and optimizing the printing effect of the splicing position.

[0021] Furthermore, white boards are provided on both sides of the scanning area, and an image of the white board is scanned while scanning the paper, and white correction is performed on the image. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the steps of the method for adjusting the consistency of the digital printing nozzle of the present invention;

[0023] Figure 2 is a view of a correction-specific pattern;

[0024] Figure 3 It is a schematic diagram of the relative arrangement positions of the line array camera, the illumination light source and the paper;

[0025] Figure 4 yes.

[0026] 1. Linear array camera; 2. Light source; 3. Paper; 4. Image scanning area; 5. Whiteboard. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0028] Example:

[0029] A method for adjusting the consistency of a digital printing nozzle, such as Figure 1 As shown, the following steps are included:

[0030] Step S1: Preparation: pre-print the calibration pattern on the reference printer according to the standardized process, calculate the Lab value of the same chromaticity color block at each position of the full-width, calculate the average value, and save it as the reference value SLab;

[0031] Step S2: Start calibration and use the printer to be calibrated to print a calibration pattern.

[0032] Correction special pattern, such as Figure 2 As shown, it contains multiple color blocks; each nozzle corresponds to a pattern, and each pattern is the same. Figure 2 The patterns corresponding to the first, second and Nth nozzles are shown in FIG. 1 , with some omissions in between.

[0033] Step S3: After printing is completed, stop printing and paper feeding; start image scanning; after the image is scanned, transmit it to the image processor for image processing. In this example, a line array camera is used for image scanning.

[0034] If the paper transmission direction is defined as left-right, the image scanning direction is along the front-back direction. Figure 3 Compared with the method of scanning in parallel with the paper direction, the color difference caused by the different optical characteristics between pixels of the linear array imaging system can be eliminated, greatly improving the test accuracy.

[0035] A correction plate is provided on the front and rear sides of the correction-specific pattern printed in step S2, and the image of the correction plate is also collected during the image scanning process. In this embodiment, the correction plate adopts a white plate for white correction of the image. Automatic white point calculation is performed according to the measured value of the white plate, and white correction is performed on the image; in the width direction of the image, flat field correction is implemented, and the point color difference of different pixel positions of the line scan is corrected. The white plate adopts white ceramic or polytetrafluoroethylene material or spray-coated diffuse reflective material.

[0036] In other embodiments, color palettes of other colors, such as green, red, blue, yellow, etc., may be added to perform multi-color correction to increase the accuracy of color correction; through correction, fluctuations of light sources and sensors over time can be resolved, thereby increasing the accuracy of color measurement.

[0037] Step S4: Calculate the Lab values ​​of all the color blocks of the nozzles of the printer to be calibrated, calculate the difference of each nozzle according to the pre-processed reference value Slab, and calculate ΔE00.

[0038] Step S5: Calculate each nozzle one by one and optimize the nozzle parameters. When ΔE00 reaches the minimum, it is considered to be optimal and the relevant parameters are stored.

[0039] Step S6: Output the adjustment coefficient of each nozzle.

[0040] The image scanning process also involves the lighting source used in conjunction with the line array camera. The lighting source is a strip light source that is consistent with the width of the paper, that is, extends in the front-to-back direction, and is suspended in the air to illuminate the paper below. The lighting source uses an LED constant current and constant temperature light source. Since the stability of LED color depends on current and temperature, it is driven by a constant current source to ensure stable brightness. The constant temperature system achieves constant temperature management through water cooling and automatic temperature control systems, which can ensure the short-term stability of the imaging system over time.

[0041] A device for adjusting the consistency of a digital printing nozzle includes at least one processor, at least one memory, and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, the above-mentioned adjustment method is implemented.

[0042] The memory is used to store non-temporary computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc. The processor may be a central processing unit (CPU) or other forms of processing units with data processing capabilities and / or instruction execution capabilities, and may control other components in the computer device to perform desired functions.

[0043] The "connection" mentioned in the present invention includes direct and indirect connection unless otherwise specified. In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0044] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0045] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A method for adjusting the consistency of a digital printing nozzle, characterized in that: The following steps are involved: S1: Preparation: pre-print the calibration pattern on the reference printer according to the standardized process, calculate the Lab value of the same chromaticity color block at each position of the full-width, calculate the average value, and save it as the reference value SLab; S2: Start calibration, and use the printer to be calibrated to print a special calibration pattern; S3: After printing is completed, image scanning begins; S4: Calculate the Lab values ​​of all the color blocks of the printer to be calibrated, calculate the difference of each nozzle according to the pre-processed reference value Slab, and calculate ΔE00; S5: Calculate each nozzle one by one, optimize the nozzle parameters, and when ΔE00 reaches the minimum, the optimum is reached and the relevant parameters are stored; S6: Output the adjustment coefficient of each nozzle.

2. The method for adjusting the consistency of a digital printing nozzle according to claim 1, characterized in that: In step S3, after the image is scanned, it is transmitted to the image processor.

3. The method for adjusting the consistency of a digital printing nozzle according to claim 2, characterized in that: If the paper conveying direction is defined as left-right, the image scanning direction is defined as front-back.

4. The method for adjusting the consistency of a digital printing nozzle according to claim 3, characterized in that: A correction plate is provided at the front and rear sides of the correction-specific pattern printed in step S2, and during the image scanning process, the image of the correction plate is also collected.

5. The method for adjusting the consistency of a digital printing nozzle according to claim 4, characterized in that: The correction plate is a white plate, which is used for performing white correction on the image.

6. The method for adjusting the consistency of a digital printing nozzle according to claim 1, characterized in that: In step S3, a line array camera is used to perform image scanning.

7. The method for adjusting the consistency of a digital printing nozzle according to claim 6, characterized in that: The lighting source used in conjunction with the line array camera adopts an LED constant current constant temperature light source.

8. A device for adjusting the consistency of a digital printing nozzle, characterized in that: The method comprises at least one processor, at least one memory and computer program instructions stored in the memory, and when the computer program instructions are executed by the processor, the adjustment method according to any one of claims 1 to 7 is implemented.

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