阅读说明：本技术 一种套准靶标的采集方法 (Method for collecting registration target ) 是由 杨皓琨 陈聪 高伟晋 包振健 李先军 于 2021-08-24 设计创作，主要内容包括：本申请公开了一种套准靶标的采集方法,所述方法在每组靶标之首设置光电靶标和校准靶标,所使用的视觉套色系统在图像采集设备的上游设置传感器,利用所述传感器作为触发器,通过所述传感器识别光电靶标来发送触发信号,所述图像采集设备根据所述传感器发出的触发信号经过一定延时后被启动,从而精准地控制图像采集时机,使所采集的图像能够仅包括目标套准靶标,并且,所述目标套准靶标已被消除角度误差。(The application discloses method for collecting registration targets, the method sets up photoelectricity target and calibration target at the head of every group target, and the vision chromatography system who uses sets up the sensor at image acquisition equipment's upper reaches, utilizes the sensor is as the trigger, through sensor discernment photoelectricity target sends triggering signal, image acquisition equipment basis triggering signal that the sensor sent is started after certain time delay to control the image acquisition opportunity accurately, make the image of gathering can only include target registration target, and, target registration target has been eliminated the angle error.)

1. A method for acquiring a registration target is applied to a unit printer, the unit printer comprises a plurality of registration modules and a plurality of color sets, each color set is provided with one registration module, each registration module comprises a sensor, an image acquisition device and a processor, the registration modules continuously acquire images of target registration targets in the printing process, and the method for acquiring each target registration target comprises the following steps:

the sensor sends a trigger signal to the delay trigger according to the photoelectric target;

the time delay trigger sends an acquisition signal to the image acquisition device according to the trigger signal;

and the image collector collects a target image according to the collection signal.

2. The acquisition method according to claim 1, wherein before the delay trigger sends the acquisition signal to the image acquirer according to the trigger signal, the processor acquires target delay time/distance, so that the image acquirer acquires a target image according to each delay time/distance after receiving the acquisition signal, wherein the target image includes a calibration target image and a target registration target image.

3. The acquisition method according to claim 2, wherein the target delay period comprises a target registration target delay period and a calibration target delay period, and the target delay distance comprises a target registration target delay distance and a calibration target delay distance, wherein,

the target registration target delay time is the delay time from the photoelectric target to the target registration target; the calibration target delay time is the delay time from the photoelectric target to the calibration target;

the target registration target delay distance is the delay distance between the photoelectric target and the target registration target; the calibration target delay distance is the delay distance between the photoelectric target and the calibration target.

4. The acquisition method according to claim 2, wherein calculating the calibration target delay time or target registration target delay time comprises:

obtaining the distance between the photoelectric target and the calibration target/target registration target;

acquiring a paper feeding speed;

and calculating the time delay of the calibration target/the target registration target according to the distance between the photoelectric target and the calibration target/the target registration target and the paper feeding speed.

5. The method according to claim 4, wherein the distance between the photoelectric target and the calibration/target registration target is a predetermined value; the paper feeding speed is a preset value or an actual value.

6. The acquisition method as set forth in claim 2, wherein obtaining the calibration target delay distance or the target registration target delay distance comprises:

acquiring the number of encoder points between the photoelectric target and the calibration target/target registration target;

acquiring the resolution of a printing machine encoder;

and calculating the delay distance of the calibration target or the delay distance of the target registration target according to the number of the encoder points and the resolution of the encoder of the printing machine.

7. The method according to claim 2, wherein for the scheme of acquiring the target image according to each of the delay distances, if the target image in the acquired target image is incomplete or not located in the center of the image, then:

calculating a delay distance offset correction value;

and correcting the delay distance according to the delay distance offset correction value.

8. The method according to claim 2, wherein for the scheme of acquiring the target image according to each of the delay periods, if the target image in the acquired image is incomplete or not located in the center of the image, then:

calculating a delay time offset correction value;

and correcting the delay time according to the correction value of the delay time.

9. The acquisition method of claim 7, wherein calculating a delay distance offset correction value comprises:

determining the central coordinates of the target image;

and calculating to obtain a distance offset correction value according to the deviation between the center of the target image and the center of the image and the resolution of the image.

10. The acquisition method according to claim 7, wherein calculating the delay duration correction value comprises:

determining the central coordinates of the target image;

calculating to obtain a distance offset correction value according to the deviation between the center of the target image and the center of the image and the resolution of the image;

and calculating a delay time length correction value according to the distance deviation correction value and the paper feeding speed.

Technical Field

The application belongs to the field of printing, and particularly relates to a method for collecting a registration target.

Background

The printing machine of the multi-color group is generally used for printing a complex pattern with colors by nesting different color groups, and before formal printing, the printing machine is debugged to ensure that a plurality of color groups are accurately matched, so that a printed product obtained by printing meets the requirement of printing precision, and the process is called registration. High-quality printed matter generally requires higher registration accuracy, and in order to realize registration accuracy control, a registration deviation value needs to be measured accurately in time, so that color register parameters are continuously corrected.

In the prior art, a method for detecting a misregistration value in real time includes a registration scheme based on a visual method, and generally, the registration scheme based on the visual method first photographs a color patch group, identifies a color patch image from an image obtained by photographing, determines a single color patch region according to the color patch image, and then photographs at a fixed time according to the identified region. However, the above-described scheme has at least the following problems: 1. the camera used for taking pictures needs a larger field of view, resulting in low resolution and poor measurement accuracy; 2. the color code position needs to be searched again after the printing plate is changed every time; 3. the photo opportunity cannot be adjusted in real time, and therefore, the accumulated error continuously increases with the continuous increase of the printing length, so that the position of the photo opportunity and the position of the registration target are staggered, and finally, the acquired registration target image cannot be used for calculating the registration deviation value or cannot reflect the registration deviation value of the target color set.

Disclosure of Invention

For solving the problems existing in the prior art, the application provides an acquisition method of registration targets, the method sets up a photoelectric target and a calibration target at the head of each group of targets, a used visual registration system sets a sensor at the upstream of image acquisition equipment, the photoelectric target and the sensor are used as triggers, the image acquisition equipment is started according to a trigger signal sent by the sensor, so that the image acquisition opportunity is accurately controlled, images acquired by image acquirers in each color group can only include the target registration targets, and the target registration targets are eliminated from angle errors.

The present application aims to provide the following aspects:

in a first aspect, the present application provides a method for acquiring a registration target, where the method is applied to a set-type printing machine, the set-type printing machine includes a registration module and a plurality of color sets, each color set is configured with one registration module, each registration module includes a sensor, an image collector and a processor, the registration module continuously acquires an image of the registration target during a printing process, and the method for acquiring each target registration target includes:

the sensor sends a trigger signal to the delay trigger according to the photoelectric target;

the time delay trigger sends an acquisition signal to the image acquisition device according to the trigger signal;

and the image collector collects a target image according to the collection signal.

In an implementation manner, before the time delay trigger sends the acquisition signal to the image acquirer according to the trigger signal, the processor respectively obtains a calibration target time delay duration/distance and a target registration target time delay duration/distance, so that the image acquirer acquires a target image according to each time delay duration/distance after receiving the acquisition signal, where the target image includes a calibration target image and a target registration target image.

In one implementation, the target delay time includes a target registration target delay time and a calibration target delay time, and the target delay distance includes a target registration target delay distance and a calibration target delay distance, where the target registration target delay time is a delay time from the photoelectric target to the target registration target; the calibration target delay time is the delay time from the photoelectric target to the calibration target; the target registration target delay distance is the delay distance between the photoelectric target and the target registration target; the calibration target delay distance is the delay distance between the photoelectric target and the calibration target.

Further, calculating the target image delay time comprises:

obtaining the distance between the photoelectric target and the target;

acquiring a paper feeding speed;

and calculating the target delay time according to the distance between the photoelectric target and the paper feeding speed.

In the application, the distance between the photoelectric target and the target is a preset value; and/or the acquired paper feeding speed is a preset value or an actual measured value.

In this application, obtaining the target delay distance includes:

acquiring the number of encoder points between the photoelectric target and the target;

acquiring the resolution of a printing machine encoder;

and calculating the delay distance of the calibration target or the delay distance of the target registration target according to the number of the encoder points and the resolution of the encoder of the printing machine.

In one implementation, for the scheme of acquiring the target image according to each of the delay distances, if the image in the acquired target image is incomplete or not located in the center of the image, then:

calculating a delay distance offset correction value;

and correcting the delay distance according to the delay distance offset correction value.

Optionally, calculating the range offset correction value comprises:

determining the central coordinates of the target image;

and calculating a delay distance offset correction value according to the deviation between the center of the target image and the center of the image and the resolution of the image.

In one implementation, for the scheme of acquiring target images according to each of the delay periods, if the target image in the acquired image is incomplete or not located in the center of the image, then:

calculating a delay time offset correction value;

and correcting the delay time length according to the delay time length offset correction value.

Further, calculating the delay time duration offset correction value includes:

determining the central coordinates of the target;

calculating to obtain a distance offset correction value according to the deviation between the target center and the image center and the resolution of the image;

and calculating a delay time length offset correction value according to the distance offset correction value and the paper feeding speed.

In a second aspect, the present application further provides a program for acquiring a registered target, which is used to implement the steps of the method for acquiring a registered target according to the first aspect when executed.

In a third aspect, a computer readable storage medium has stored thereon computer instructions which, when executed by a processor, implement the steps of the method for acquiring a registration target according to the first aspect.

Compared with the prior art, the triggering of the image collector in the method provided by the application depends on the physical photoelectric target, so that the triggering time is more accurate, and the accumulated error is eliminated; in addition, according to the method, after the registration target image is collected, the image is immediately analyzed and processed by using an independent processor to generate the registration deviation value of the color set, so that the system delay is shortened, the processing efficiency is improved, on the other hand, the registration modules are mutually independent, the modularization of the printing machine is enhanced, and the maintenance and the use are more convenient; in addition, the method provided by the application can accommodate the stretching deformation of the printing base material, and the maximum stretching deformation of the conventional printing base material is calculated.

Drawings

FIG. 1 shows a flow chart of a method of acquiring a registered target provided herein;

FIG. 2 shows a preferred one-plate week of chromatography targets in the present application.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of methods consistent with certain aspects of the invention, as detailed in the appended claims.

The method for acquiring the registered target provided by the present application is described in detail by the following specific examples.

First, a brief introduction is made to a usage scenario of the present solution.

The printing equipment that this application used is the printing machine of unit formula polychrome group, and is different with traditional polychrome group printing machine chromatography system, and the printing machine of unit formula polychrome group that this application used includes a plurality of mutually independent chromatography subsystems, and every chromatography subsystem includes a colour group and a registration module, and wherein, every registration module is special for specific colour group service, and every registration module includes a sensor, time delay trigger plate, image collector and treater at least.

In this example, each processor is in communication with the printer controller, which is a controller that performs adjustment of the physical position and printing parameters of each color set in the printer, so that the processor can send the calculated correction parameters to the printer controller to enable each color set to adjust the color register parameters in time.

Fig. 1 shows a flowchart of a method for acquiring registration targets according to the present application, as shown in fig. 1, the method includes acquiring a plurality of registration targets, and acquiring each registration target includes the following steps S101 to S103:

and S101, the sensor sends a trigger signal to the delay trigger according to the photoelectric target.

Fig. 2 shows a preferred one-plate-week color register target of the present application, and as shown in fig. 2, each of the plate-week color register targets sequentially includes a photoelectric target, a calibration target and a plurality of reference targets, wherein each of the photoelectric target and the calibration target is one, the number of the reference targets corresponds to the number of color sets, and after the color register target passes through each color set, each color set telescopically prints the color set target on the corresponding reference target, so that each color set target forms one register target with the reference target nested therewith.

It will be appreciated that different colour sets nest on different reference targets, the registration targets formed by the different colour sets being independent of one another, and optionally each colour set forming the registration target on the reference target in sequence for image acquisition.

The distance between any two adjacent reference targets is a preset value, optionally, the distance between any two adjacent reference targets may be the same or different, but whether the distances are the same or different, the distance between any two adjacent reference targets is preset, that is, the preset distance between any one reference target and the photoelectric target is known.

In this example, the optoelectronic target, the calibration target, and the reference target are printed in-situ by a first set of color sets, with subsequent color sets printing the color set targets nested in sequence on the corresponding reference targets.

In this example, before the delay trigger sends the acquisition signal to the image acquirer according to the trigger signal, the processors in the alignment modules respectively obtain a calibration target delay time length/distance and a target alignment target delay time length/distance, so that the image acquirer acquires a target image according to the delay time length/distance after receiving the acquisition signal, where the target image includes a standard target image and a target alignment target image.

It will be appreciated that the parameters of the target delay time/distance and the target registration target delay time/distance are calibrated, and the values obtained by the processors are different for the same parameter, and are related to the position of the registration module in which the processor is located.

In this example, the target registration target delay time is a delay time from the photoelectric target to the target registration target; the calibration target delay time is the delay time from the photoelectric target to the calibration target; the target registration target delay distance is the delay distance between the photoelectric target and the target registration target; the calibration target delay distance is the delay distance between the photoelectric target and the calibration target.

Furthermore, the initial value of the calibration target delay time and the target registration target delay time can be set manually, and the two delay times are adjusted continuously along with the continuous registration; similarly, the initial value of the calibration target delay distance and the initial value of the target registration target delay distance may also be set manually, and as the registration is performed continuously, the two delay distances are also adjusted continuously so that the acquired target registration target image can be located at the center of the acquired image under the condition that the printing material is deformed, in the following specific manner.

It should be noted that, in the present application, the delay time duration refers to that after the time duration is delayed, the delay trigger board sends a start signal to a specific device; the delay distance is that after the printing material is fed by the distance, the delay trigger board sends a starting signal to a specific device.

In this example, the target registration targets are continuously collected during printing, that is, the target registration targets are continuously collected during formal printing, and the registration deviation value is calculated, so that the color registration parameters are corrected in real time during printing, and the registration accuracy of the printed matter is always kept within a preset range.

In this example, the calibration target delay time is calculated in a similar manner to the target registration target delay time. The following description takes the calculation of the calibrated target delay time as an example, including:

obtaining the distance between the photoelectric target and the calibration target;

acquiring a paper feeding speed;

and calculating the time delay for collecting the calibration target according to the distance between the photoelectric target and the calibration target and the paper feeding speed.

In this example, the distance between the photoelectric target and the calibration target may be a preset value or an actual measurement value, and the distance may be input to the processor through an input device such as a control panel, or may be automatically reported to the processor by the distance measuring device.

It will be appreciated that the use of measured values makes it possible to eliminate as far as possible the errors due to the possible tensile deformation of the substrate during the paper advance.

In this example, the method for obtaining the measured value is not particularly limited, and any method of collecting the paper feeding distance of the printing material in the prior art may be used.

Similarly, the paper feeding speed may be a preset value or an actual measurement value, and the paper feeding speed may be input to the processor through an input device such as a control panel, or may be automatically reported to the processor by a speed measuring device.

In this example, the calculating the time delay for collecting the calibration target according to the distance between the photoelectric target and the calibration target and the paper feeding speed may specifically include: and calculating the quotient of the distance between the photoelectric target and the calibration target and the paper feeding speed.

In this example, the method of calculating the calibration target delay distance is similar to the calculation method of calculating the target registration target delay distance.

The following description takes the calculation of the delay distance of the calibration target image as an example:

acquiring the number of encoder points between the photoelectric target and the calibration target;

obtaining system parameters to obtain the resolution of a printer encoder;

and calculating the delay distance of the collected calibration target according to the number of the encoder points and the resolution of the printer encoder.

In this example, the number of encoder points and the resolution of the encoder of the printing machine may be preset values or measured values, and the number of encoder points and the resolution of the encoder of the printing machine may be input to the processor through the control panel or automatically reported to the processor by the measuring device.

In this example, the calculation of the collected calibration target delay distance according to the number of the encoder points and the resolution of the encoder of the printing machine may be performed by using any one of the related schemes in the prior art.

In this example, different measurement standards are essentially adopted for the delay time and the delay distance, but both measurement delay manners can improve the accuracy of acquiring the target image, and if no particular description is given, the following use of the delay time manner in this example is an example to describe the scheme of this application.

In this example, when the photoelectric target is recognized by the sensor, the photoelectric target is aligned with the sensor, the image collector is located downstream of the sensor, and the calibration target is located upstream of the photoelectric target, so the distance L between the image collector and the calibration target can be calculated according to the following formula (1):

L-L1 + L2 formula (1)

Wherein, L1 represents the distance between the sensor and the image collector, and L2 represents the distance between the photoelectric target and the calibration target.

In this example, the paper feeding speed is a preset value, or may be acquired in real time according to a detection device.

Further, the calibration target delay time T may be calculated according to the following formula (2):

L/V type (2)

Wherein L represents the distance between the image collector and the calibration target position; v represents the paper feed speed.

In this example, calculating the target registration target image delay time duration may include two ways, one is a direct calculation method and the other is an indirect calculation method, wherein the specific process of the direct calculation method is similar to the method of calculating the calibrated target image delay time duration, except that L2 is replaced by the distance between the target reference target and the calibrated target, specifically, the following steps are included:

acquiring the distance between an image collector and a target registration target;

acquiring a paper feeding speed;

and calculating the delay time for acquiring the target registration target according to the distance between the image acquisition device and the target registration target and the paper feeding speed.

In this embodiment, another way, that is, an indirect calculation method may calculate a time difference between acquiring the calibration target and acquiring the target registration target, in the method, the time delay duration of the target registration target image may be a time difference between the photoelectric target and the target registration target, or a time difference between the calibration target and the target registration target.

Specifically, the indirect calculation method may include the steps of:

obtaining the distance between a target registration target and the calibration target;

acquiring a paper feeding speed;

and calculating the time delay of the target registration target image according to the distance between the target registration target and the calibration target and the paper feeding speed.

In the indirect method, the distance between the target registration target and the calibration target is a preset value, and the paper feeding speed may be a set value or an actual measurement value as described above.

Further, the time difference T' between the calibration target and the target registration target can be calculated according to the following formula (3):

t '═ L'/V type (3)

Wherein L' represents the distance between the target registration target and the calibration target.

In this example, if the time difference between the photoelectric target and the target registration target is taken as the delay time, the delay time is the sum of T and T'; if the time difference between the calibration target and the target registration target is taken as the delay time length, the delay time length is T'.

According to the method, the physical signal of the photoelectric target is used as the trigger signal, so that the time delay trigger plate can accurately control the image acquisition time, the visual field of the image acquisition device can be reduced, the resolution of the obtained target registration target image is higher under the same shooting condition, and the calculated registration deviation value is more accurate and reliable.

Furthermore, the delay time of each registration module is independently calculated and set without mutual interference, so that the setting and modification of parameters are greatly simplified, and the system maintenance is facilitated.

And step S102, the time delay trigger sends a collecting signal to the image collector according to the trigger signal.

In this example, the delay trigger starts timing after receiving the trigger signal, and sends a start signal to the image collector after timing to a corresponding delay time, and the image collector starts operation according to the start signal.

For example, the time delay trigger starts timing after receiving the trigger signal, sends a start signal to the image collector after the time reaches the time delay of the calibration target, and the image collector starts operation according to the start signal to collect the image of the calibration target.

And the delay trigger continues to operate until the delay time of the target registration target is timed, the starting signal is sent to the image collector again, the image collector is triggered again, the operation is started, and the image of the target registration target is collected.

And after a second starting signal is sent to the image collector, the time delay trigger stops timing and returns to zero.

And step S103, the image collector collects a target image according to the collection signal.

In this example, the image collector sequentially collects a calibration target image and a target registration target image according to the collection signal.

In this example, the field of view of the image collector is slightly larger than the larger size of the calibration target and the target registration target image, so that the image in the collected image occupies the largest proportion of the image in the image, for example, the field of view of the image collector is 200% of the outer diameter of the double-ring target.

In this example, the target size of each color set is the same for each color set to facilitate setting the field of view of the image collector.

In this example, the calibration target may be a cross-shaped mark, the reference target may be an annular target, and the registration target is also an annular target, and the outer diameter of the registration target is larger than the inner diameter of the reference target.

In this example, if the target image in the acquired calibration target image and/or the target registration target image is incomplete or not located in the center of the image, calibration inaccuracy of the image acquirer or set deviation calculation inaccuracy may be caused, and therefore, the delay time may be adjusted to complete the target image, specifically, the method may include the following steps:

step S141, calculating a delay distance offset correction value;

and step S142, correcting the delay distance according to the delay time length correction value.

Further, the calculating the delay distance offset correction value includes:

in step S1421, the center coordinates of the target image are determined.

In this example, any method of determining the center coordinates of the image on the image in the prior art may be used. For example, the outer edge of the target image is determined first, and then the geometric center of the target image is determined.

The method for determining the outer edge of the target image is not particularly limited, and any method for determining the outer edge of the image on the image in the prior art may be used.

Further, the method for determining the geometric center of the target image is not particularly limited, and any method for determining the geometric center of the image in the prior art may be used. For example, the target used in the present application is a circular ring, and therefore, the geometric center of the target image can be deduced according to the geometric principle, for example, three points can determine the position of the center of the circle. It will be appreciated that the geometric center of the target image may be beyond the image, but the coordinates of the point may still be determined in a coordinate system established based on the acquired image.

Step S1422, calculating a delay distance offset correction value according to the deviation between the geometric center of the target image and the geometric center of the image and the image resolution.

In this example, the delay duration correction value may calculate a physical distance between two geometric centers using a pixel distance between the two geometric centers and an image resolution, so that the target image is located at the center of the image to the maximum extent after adjustment, so as to reduce a calculation error caused by distortion of the image acquired by the image acquirer.

If the triggering delay board delays time by a delay duration meter, if the target image in the collected calibration target image and/or the target registration target image is incomplete or not located in the center of the image, the method further comprises the following steps:

and calculating a delay time length offset correction value according to the distance offset correction value and the paper feeding speed.

In this example, the delay time length offset correction value is determined by dividing the distance offset correction value calculated as described above by the paper feed speed.

In this example, the image collector, if rotated about an axis perpendicular to the imaging plane, results in a large error in the measurement of the misregistration value. Specifically, assuming that the angular deviation of the image pickup is 1 °, if the registration deviation is 1mm, the error due to the angular deviation is 0.9mm × sin (1 °) to 0.016mm, which is considered to be a large deviation in the process printing, and therefore, it is necessary to perform correction.

In this example, after the calibration target image is collected, the installation angle of the image collector may be calibrated according to the calibration target image, and if the deviation of the installation angle exceeds a preset range, the installation angle of the image collector may be corrected.

The application also provides a program for acquiring the registered target, and the program is used for realizing the steps of the method for acquiring the registered target when being executed.

The present application also provides a computer readable storage medium having stored thereon computer instructions which, when executed by a processor, implement the steps of the aforementioned method for acquiring a registration target.

Compared with the prior art, the triggering of the image collector in the method provided by the application depends on the physical photoelectric target, so that the triggering time is more accurate, and the accumulated error is eliminated; in addition, according to the method, after the registration target image is collected, the image is immediately analyzed and processed by using an independent processor to generate the registration deviation value of the color set, so that the system delay is shortened, the processing efficiency is improved, on the other hand, the registration modules are mutually independent, the modularization of the printing machine is enhanced, and the maintenance and the use are more convenient; in addition, the method provided by the application can accommodate the stretching deformation of the printing base material, and the maximum stretching deformation of the conventional printing base material is calculated.

The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.