CN113568589A

CN113568589A - Method, device and equipment for judging printing precision and storage medium

Info

Publication number: CN113568589A
Application number: CN202110873673.8A
Authority: CN
Inventors: 吴飞; 张明涛; 黎子滢
Original assignee: Sencai Digital Printing Technology Shenzhen Co ltd
Current assignee: Sencai Digital Printing Technology Shenzhen Co ltd
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2021-10-29

Abstract

The invention belongs to the technical field of printing, solves the technical problem that the judgment of the existing printing precision is overlarge due to subjective judgment factors, and provides a method, a device, equipment and a storage medium for judging the printing precision. The method for judging the printing precision comprises the following steps: acquiring a dot image formed by jetting the ink on a printing medium once by a nozzle; establishing a coordinate system which is positioned on the same plane with the ink dot image; acquiring coordinate information of each ink dot in the ink dot image in the coordinate system; calculating the characteristic information of the ink dot image according to the coordinate information corresponding to each ink dot; and comparing the characteristic information of the ink dot image with preset conditions to obtain a comparison result, and judging the printing precision according to the comparison result. The invention provides a method for calculating the characteristic information of a dot image, and then the printing precision is judged, so that the artificial participation is reduced, the intelligent judgment of the printing precision is realized, and the reliability of the precision judgment is improved; the method has the effect of quickly and accurately judging the printing precision.

Description

Method, device and equipment for judging printing precision and storage medium

Technical Field

The present invention relates to the field of printing technologies, and in particular, to a method, an apparatus, a device, and a storage medium for determining printing accuracy.

Background

Ink-jet printing is a non-impact dot-matrix printing technique, in which ink droplets are ejected from a micro-device and, according to preset control conditions, the ink droplets fly to the surface of a medium to directly form a printed image at a specified position. The accuracy of the drop position of the ink dots, the size of the ink dots and whether the distribution of the ink dots is uniform determine the actual accuracy of the printed image, and further influence the overall printing accuracy.

At present, the printing precision is judged by observing whether the printing precision meets the requirement or not by people, and a unified and scientific test judgment method and standard are lacked. However, the printing precision is judged by means of human visual observation, subjective thinking and experience dominate, different printing precision judgment results exist for different people, printing is fine work, human eye judgment has certain limitation, and precision judgment cannot be accurately described. Therefore, in the prior art, the judgment of the printing precision is too large as a subjective judgment factor, so that the judgment is not accurate enough.

Disclosure of Invention

In view of this, embodiments of the present invention provide a method, an apparatus, a device, and a storage medium for determining printing precision, where the determination of printing precision is caused by too large subjective determination factors, resulting in a technical problem of inaccurate determination.

In a first aspect, an embodiment of the present invention provides a method for determining printing accuracy, where the method includes: acquiring a dot image formed by jetting the ink on a printing medium once by a nozzle; establishing a coordinate system which is positioned on the same plane with the ink dot image; acquiring coordinate information of each ink dot in the ink dot image in the coordinate system; calculating the characteristic information of the ink dot image according to the coordinate information corresponding to each ink dot; and comparing the characteristic information of the ink dot image with preset conditions to obtain a comparison result, and judging the printing precision according to the comparison result.

Further, the characteristic information of the dot image is calculated according to the coordinate information corresponding to each dot: processing coordinate information corresponding to all ink dots in the ink dot image to obtain a reference line; calculating the variance of each ink point in the ink point image from the reference line; and taking the variance as the feature information.

Further, the step of processing the coordinate information corresponding to all the dots to obtain the reference line includes: and performing linear fitting on the coordinate information corresponding to all the ink points to obtain a linear equation of the reference line.

Further, the step of calculating the feature information of the dot image according to the coordinate information corresponding to each dot includes: acquiring contour coordinate information of each ink dot; calculating the diameter of the corresponding ink dot according to the contour coordinate information of each ink dot; calculating the diameter variance of all the ink dots according to the diameter of each ink dot; and taking the diameter variance as the characteristic information.

Further, the step of acquiring contour coordinate information of each dot further comprises, before the step of acquiring contour coordinate information of each dot: and acquiring the ink dot outline information of the ink dot image under a preset tolerance value.

Further, the step of calculating the feature information of the dot image according to the coordinate information corresponding to each dot includes: acquiring the number of ink flying points in a preset range of each ink dot; and taking the number of the ink flying points as the characteristic information.

Further, the acquiring of the dot image formed once by the nozzle ejecting on the printing medium includes: acquiring an original image formed by jetting a nozzle on a printing medium once;

and amplifying the original image to obtain the ink dot image.

A second aspect of the present invention provides an apparatus for determining printing accuracy, the apparatus comprising: the first acquisition module acquires a dot image formed by jetting the nozzle on the printing medium once; the establishing module is used for establishing a coordinate system which is positioned on the same plane with the ink dot image; the second acquisition module is used for acquiring the coordinate information of each ink dot in the ink dot image in the coordinate system; the computing module is used for computing the characteristic information of the ink dot image according to the coordinate information corresponding to each ink dot; and the judging module is used for comparing the characteristic information of the ink dot image with preset conditions to obtain a comparison result and judging the printing precision according to the comparison result.

A third aspect of the present invention provides a printing apparatus comprising: at least one processor, at least one memory, and computer program instructions stored in the memory that, when executed by the processor, implement a method as in any of the above.

A fourth aspect of the invention provides a storage medium having stored thereon computer program instructions which, when executed by a processor, implement a method as defined in any one of the preceding claims.

In conclusion, the beneficial effects of the invention are as follows:

by establishing a coordinate system, coordinate information corresponding to the ink dots is found out, and then relevant parameters capable of reflecting printing precision are calculated. The invention provides a uniform standard for printing precision, and adopts a scientific calculation method to calculate the characteristic information of the ink dot image and judge the printing precision, thereby reducing the artificial participation and improving the reliability of precision judgment; the method has the effect of quickly and accurately judging the printing precision.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and for those skilled in the art, without any creative effort, other drawings may be obtained according to the drawings, and these drawings are all within the protection scope of the present invention.

FIG. 1 is a flow chart of a method of adjusting drive waveforms at different temperatures based on a printed image according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method of adjusting drive waveforms at different temperatures based on a printed image according to an embodiment of the present invention;

FIG. 3 is a flow chart of a method of adjusting drive waveforms at different temperatures based on a printed image according to an embodiment of the present invention;

FIG. 4 is a flow chart of a method of adjusting drive waveforms at different temperatures based on a printed image according to an embodiment of the present invention;

FIG. 5 is a flow chart of a method of adjusting drive waveforms at different temperatures based on a printed image according to an embodiment of the present invention;

FIG. 6 is a flowchart of a method for determining printing accuracy according to a second embodiment of the present invention;

FIG. 7 is a flowchart of a method for determining printing accuracy according to a second embodiment of the present invention;

FIG. 8 is a flowchart of a method for determining printing accuracy according to a second embodiment of the present invention;

FIG. 9 is a diagram of a coordinate system established in the method for determining printing accuracy according to the second embodiment of the present invention;

FIG. 10 is a diagram of another coordinate system established in the method for determining printing accuracy according to the second embodiment of the present invention;

FIG. 11 is a schematic view of an apparatus according to a third embodiment of the present invention;

fig. 12 is a schematic diagram of an apparatus according to a fourth embodiment of the present invention.

In the figure:

1. a first acquisition module; 2. establishing a module; 3. a second acquisition module; 4. a calculation module; 5. and a judging module.

Detailed Description

Features and exemplary embodiments of various aspects of the present invention will be described in detail below, and in order to make objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The present invention is described in further detail below with reference to fig. 1-12.

Example one

In one aspect, an embodiment of the present invention provides a method for adjusting driving waveforms at different temperatures based on a printed image, as shown in fig. 1, the method includes:

s1, acquiring a reference flying speed of the ink drop and a printed reference printing image when the nozzle is driven to jet the ink drop with the specified ink amount by adopting a preset driving waveform at the reference temperature for printing;

the preset driving waveform is generated at a reference temperature and corresponds to the temperature, and the preset waveform can be set according to ink provided by a manufacturer and a reference waveform given by a corresponding printing nozzle or according to a use habit. The printing effect of printing can be reflected visually by referring to the printed image and the flying speed of the reference ink drop during printing; that is, generally speaking, the reference value is selected to be the temperature closest to the room temperature, generally from 25 ℃ to 30 ℃, preferably 25 ℃, generally speaking, the waveforms of the ink and the print head working at the room temperature are more conventional, the printing effect is better, and the influence of other variable factors is less, therefore, the reference value is selected to be the reference value at the room temperature, and the printing effect of all the waveforms is improved. In the present embodiment, the designation of the ink volume means that the ink droplets of the ink volumes of the large, medium and small dots need to be printed according to the printing requirements, and different printing ink droplets need to be printed due to different printing requirements, so that the reference images of the ink droplets of the ink volumes of the large, medium and small dots need to be acquired correspondingly.

S2, acquiring a first flight speed of ink drops and a printed first print image when the preset drive waveform is adopted to drive the nozzle to jet the ink drops with the specified ink amount for printing at a first temperature;

printing at a first temperature according to a preset driving waveform, and observing an obtained first printed image and a first flying speed; judging whether the printing deviation of the same waveform at different temperatures has influence or not; if the change rule of the ink along with the temperature is confirmed, printing can be carried out based on another driving waveform different from the preset driving waveform.

S3, evaluating the image quality and the first flying speed of the first printed image according to the reference printed image and the reference flying speed to generate a preliminary evaluation result;

the printing effect at the reference temperature is obtained, and then the waveforms at different temperatures are debugged according to the printing effect, so that all the printing effects are consistent. When the waveform is debugged, relevant parameters of the waveform can be adjusted according to the change of the viscosity of the ink along with the change of the temperature, and the waveform with the same printing effect at different temperatures is formed.

S4, adjusting the preset driving waveform to generate an alternative driving waveform according to the preliminary evaluation result;

and generating a preliminary evaluation result according to the evaluation, and setting the printing alternative waveform.

S5, acquiring a second flying speed of the ink drop and a printed second print image when the nozzle is driven to eject the ink drop with the specified ink amount by adopting the alternative driving waveform at the first temperature for printing;

a second print image associated with printing and a second drop flight speed are further acquired.

S6, evaluating the image quality and the second flying speed of the second printed image according to the reference printed image and the reference flying speed to generate an intermediate evaluation result;

and comparing the printed image printed at the first temperature by the different driving printing waveforms each time with the acquired second flying speed.

And S7, recording the alternative driving waveform as the designated driving waveform at the first temperature when the intermediate evaluation result meets the preset condition.

The preset condition may be that whether the printed images of the two are within a range of phase difference is evaluated, and the difference between the two flying speeds is also within a preset range, so that the printing effects of the waveforms at the two different temperatures are confirmed to be consistent, and then the waveforms with consistent printing effects are confirmed at the different temperatures.

In this embodiment, the printing effect of the preset driving waveform at a certain temperature is used as a reference value, and the waveforms at different temperatures are debugged according to the printing effect, so that the consistency of each printing effect is within a preset range, different waveforms are used for controlling printing at different temperatures, and the consistency of the printing effects at different temperatures is ensured. The invention not only emphasizes that all printing effects are good, but also more importantly, the printing effects at different temperatures are consistent. The technical problems that in the prior art, the printing effect of waveforms at different temperatures is far different in the printing process and the stability of actual production is influenced are solved. The printing effect under each temperature point is consistent along with the change of the temperature, thereby ensuring the production stability; the printing effect is consistent under different temperatures, and the printing effect of the final product is stable.

Preferably, as shown in fig. 2, the evaluating the image quality and the first flying speed of the first printed image according to the reference printed image and the reference flying speed, and generating a preliminary evaluation result includes:

s31, respectively acquiring printing fluency, printing precision, printing flying ink number and printing color gamut difference values of the reference printing image and the first printing image;

the flying speed of the ink drop is measured by introducing a waveform on an ink drop observer and testing the flying speed of the ink drop and the volume of the ink drop. The flying speed of the ink drop is determined by positioning an ink drop observer, and the distance between 100ms and 200ms after the ink drop is ejected from a nozzle plate of the nozzle is obtained, so that the flying speed of the ink drop is obtained. The test method is that firstly, an ink drop observer is used for observing ink jet of the nozzle, and the ink drop positioning is recorded at 100 ms. The drop placement is then recorded again at 200 ms. And finally, calculating the flying speed of the ink drop according to the moving distance of the ink drop in the time period of 100ms to 200 ms. The flying speed test at the reference temperature requires that the flying speed of the ink drop is within a normal controllable range, and the driving waveform is used as the first driving waveform which can be used at the temperature point. The volume and the shape of the ink drop can be acquired by a screen shot when the ink drop observer measures the ink drop.

The printing fluency test is to determine whether the ink meets the continuous printing requirement in the current environment under the normal working state of the printer. The specific steps comprise: before testing, firstly checking whether the states of the nozzles are all out, and recording a printing state strip. Aiming at the inks with different colors, different testing methods exist, and more specifically, aiming at the color inks, feathering in 6pass is used for printing four-color black with the total ink quantity of 1.2m multiplied by 1m for 3 times, and the recording and printing state strip and the surface area ink quantity of the nozzle plate of the nozzle are obtained. If the printing state is qualified, feather printing is carried out for 3 times by 6 passes to obtain 1.5m multiplied by 5m full ink volume four-color black, and the printing state strip and the surface area ink volume of the nozzle plate of the nozzle are rapidly obtained. For white ink, before testing, whether the states of the nozzles are all out is checked, and a printing state bar is recorded. And (4) using the total ink amount of 1.2m multiplied by 1m of the 6pass feathering and beating for 3 times to obtain the printing state strip and the surface area ink amount of the nozzle plate of the nozzle. And (3) feathering and beating the ink with the total ink amount of 1.5m multiplied by 5m for 3 times by 6pass to quickly obtain the ink amount of the surface area of the printing state strip and the nozzle plate of the nozzle. The color ink fluency test standard is that the color ink is printed for 3 times with the full ink volume and four color inks with the breadth of 1.2m multiplied by 1m, the number of broken lines of a channel is obtained, if the number of the broken lines is within 3, the color ink is judged to be qualified in terms of printing fluency, and the driving waveform is used as a first driving waveform which can be used at the temperature point. The white ink fluency test standard is that the printing breadth is 1.2m multiplied by 1m, the full ink amount is white for 3 times, the channel broken line number is obtained, if the broken line number of each channel is within 5, the fluency of the white ink is judged to be qualified, and the driving waveform is used as the first driving waveform which can be used under the temperature point.

The acquisition step of the number of the printing flying ink dots comprises the following steps: acquiring a local amplified color block image of the reference image; and acquiring the edge of the color block diagram, and judging whether the number of the ink flying dots exists or not. The method for acquiring the number of flying ink points comprises the following steps: and acquiring a printed 6pass color block diagram, and judging the number of ink flying points at the edge of the color block diagram. If the number of the flying ink dots is 0, the quality of the printing of the driving waveform is considered to be qualified, and the driving waveform is used as the first driving waveform which can be used at the temperature point.

The color gamut difference test means that the color representation of the printed color block is represented in a digitalized form by a Lab color model. The color gamut difference testing method comprises the following steps: checking whether the state of the spray head is normal; acquiring eight color patch images of 100% C, 100% M, 100% Y, 100% K, R, G, B and 100% CMYK which are respectively printed by adopting driving waveforms; then obtaining color gamut values corresponding to all the color block graphs; and calculating the difference value between the color gamut values corresponding to the color lump graphs as the color gamut difference value. The Lab values for the CMYK four colors at maximum ink volume can be recorded after the values are obtained using the i1Profile scan. If the color gamut testing standard is provided with a standard color sample, the color gamut difference value of the color blocks printed by the waveform is judged to meet the requirement if the delta E2000<1 of the standard color sample and the standard color sample exist, and the driving waveform is used as the first driving waveform which can be used at the temperature point.

S32, comparing the printing fluency, the printing precision, the number of printing flying ink dots and the printing color gamut difference value of the reference printing image and the first printing image; comparing the reference flying speed with a first flying speed;

and S33, generating a preliminary evaluation result.

In this embodiment, the 5 tests all reflect the hard index of the printing effect, and the 5 tests accurately reflect the whole printing effect by taking the printing as the evaluation standard. The general ink is evaluated from the 5 aspects, the 5 aspects test can better determine the reaction degree of the whole ink, and the driving waveform is used as the driving waveform which can be used at the temperature point only if the 5 reference standards pass the test.

Preferably, as shown in fig. 3, the adjusting the preset driving waveform to generate an alternative driving waveform according to the preliminary evaluation result includes:

s41, when the preliminary evaluation result does not meet the preset condition, adjusting at least one of the voltage, the period and the slope of the preset driving waveform;

and S42, generating an alternative driving waveform.

In the present embodiment, the waveform is adjusted according to the change in the printing effect; specifically, the change rule of the ink viscosity along with the change of the temperature can reflect the change of the printing effect; therefore, the voltage, the period and the slope of the waveform can be adjusted according to the change of the printing effect. For example, if deviation of printing precision occurs, the control voltage is adjusted up or down, if ink flying occurs, the driving pressure is not enough, the control voltage is adjusted up by a certain amount, and the specific amount needs to be adjusted according to the ink flying; of course, the voltage, the period and the slope of the driving waveform need to be adjusted simultaneously when necessary, so that the printing effect printed under the driving waveform meets the requirement.

Preferably, as shown in fig. 1, the acquiring a reference flying speed of an ink droplet when the nozzle is driven to eject the ink droplet of a specified ink amount at a reference temperature by using a preset driving waveform for printing and a printed reference print image includes:

s11, acquiring an initial printing image printed by adopting a preset driving waveform at a reference temperature and the flight speed of initial ink drops during printing;

specifically, the printing fluency, the printing precision, the number of printing flying ink dots and the printing color gamut difference value are obtained according to the printing image; the effect of printing the preset waveform at the reference temperature is in accordance with the preset effect, the good printing effect is ensured, and the printed picture is confirmed as the required reference picture.

S12, comparing the initial printing image with a preset printing image, and comparing the initial ink drop flying speed with a preset ink drop flying speed to generate a comparison result;

and S13, if the comparison result meets the preset requirement, taking the initial printing image as a reference printing image, and taking the initial flying speed as the reference flying speed.

Preferably, the reference temperature ranges are: 20-30 ℃.

In the present embodiment, waveforms at 15 ℃, 20 ℃, 30 ℃ and 35 ℃ are respectively debugged with the printing effect of the waveform at 25 ℃ as a reference; because the environment temperature is 15-35 ℃ for most of time, the temperature of the printing environment fluctuates at 15-35 ℃; the temperature in the range is selected, so that the printing has corresponding waveform control at different temperatures, and the printing effect is consistent when the printing is carried out at different temperature points.

The first temperature includes at least three different temperature points, and the first driving waveform corresponds to the first temperature.

In the present embodiment, two adjacent temperature points differ by 5 ℃. The reference temperature is set at 25 c and the selection of the reference may be closest to room temperature depending on the season and the environment. The range of the temperature points is set to be 15-35 ℃, and the difference between two adjacent temperature points is 5 ℃, because the ink has no obvious change in the range of 5 ℃, the printing effect of the ink cannot be too far apart; of course, in other embodiments, the difference between the two temperature points may be adjusted, and the size of the change of the parameters such as viscosity of the ink at different temperatures along with the change of the temperature is set according to the different types of the ink and the type of the print head.

Further, before acquiring a second flying speed of ink droplets when the nozzle is driven to eject the ink droplets of the specified ink volume for printing by adopting the alternative driving waveform at the first temperature and a printed second printing image, the method further comprises:

measuring the second flying speed, and determining the difference value between the second flying speed and the reference flying speed; and judging whether the difference value of the second flying speed and the reference flying speed accords with a preset range, wherein the difference value influences the flying speed of the ink drop generally comprises a driving waveform, and on the other hand, the nozzle is abnormal, so that the flying speed of the ink drop is influenced by the nozzle.

If the difference value is out of a preset range, determining the flight track of the ink drop; therefore, by determining whether the difference between the second flying speed and the reference flying speed is within the preset range, if not, it needs to be confirmed whether the waveform affects the flying speed or the nozzle abnormality affects the flying speed. Judging whether the nozzle is abnormal or not needs to judge the flight track of the ink drop, because the abnormal nozzle can influence the flight track of the ink drop under normal conditions, the flight track of the ink drop is determined; determining the flight trajectory of the drop includes determining an offset of the drop landing. The flight path of the ink drop is determined by confirming the offset of the ink drop.

When the flight track of the ink drop is inconsistent with a preset track, determining that the nozzle of the nozzle is abnormal; that is, it is determined that the amount of deviation of the landing position of the ink droplet is out of the preset range, it is considered that the nozzle is abnormal.

And selecting other nozzles of the sprayer as a second flying speed measuring object, and driving other nozzles of the sprayer to spray ink drops with the specified ink volume by adopting the alternative driving waveform at a first temperature for printing. Other nozzles means non-anomalous nozzles, i.e. nozzles that work normally; on the other hand, the nozzle having an abnormal condition can be corrected to a normal nozzle by correcting the nozzle, for example, determining whether the nozzle has an ink accumulation or not, and removing the ink accumulation from the nozzle. When the nozzle cannot be corrected in time, the normal ink jet can be selected as an object for obtaining the second flying speed measurement, that is, the second flying speed of the abnormal nozzle is obtained through discharge, and the flying speed of the normal nozzle is taken as the second flying speed; the problem that the flying speeds of two times of printing cannot be consistent due to abnormal nozzles is avoided, and further time is wasted because the proper waveform cannot be found by continuously debugging the waveform; has the advantage of facilitating rapid confirmation of the drive waveform.

Further, as shown in fig. 5, the method further includes: s8, acquiring first driving waveforms at all temperature points; drawing a driving waveform curve according to all the first driving waveforms; and storing the driving waveform curve.

In this embodiment, the waveform set according to the print effect is introduced into the board, and the waveform at each temperature node is calculated by the board to generate a waveform curve. The board card automatically calls the waveform at the corresponding temperature according to the detected temperature, so that the automatic temperature linkage waveform can detect the current temperature, and the board card calls the appropriate waveform; and then in the subsequent production of printing of being convenient for, when ambient temperature undulant great, the integrated circuit board can automatic identification, and the wave form is printed in the automatic call, does not need artifical detection ambient temperature's change and reset the wave form, is convenient for guarantee the continuity of printing when operational environment temperature undulant great, and has guaranteed the printing effect of whole printing in-process.

Preferably, with reference to fig. 4, after the step S8, the method further includes: respectively obtaining evaluation printing images and the flight speed of ink drops at a plurality of temperature points; and comparing whether the difference value between the reference printing image and the flying speed of the reference ink drop is in a preset range, and if so, defining the driving waveform curve as a printing waveform curve. When printing next time, directly calling the printing change waveform curve; if not, the waveform needs to be adjusted from the new one.

In the embodiment, four intermediate temperatures of 17.5 ℃, 22.5 ℃, 27.5 ℃ and 32.5 ℃ are selected, and a driving waveform curve is executed, namely, a waveform test is carried out at the intermediate temperature of two adjacent temperature points; acquiring printing images and ink drop flying speeds at the temperature points; similarly, the judgment basis of the printed image is printing fluency, printing precision, printing flying ink number and printing color gamut difference; comparing the printing effects of the four intermediate temperatures and other temperature nodes; on one hand, whether the whole driving waveform curve meets the requirement of consistent printing effect is verified, and on the other hand, whether the change of the ink at the phase difference of 2.5 ℃ can meet the consistency of the printing effect is verified.

Preferably, the evaluating the image quality and the first flying speed of the first printed image according to the reference printed image and the reference flying speed, and generating a preliminary evaluation result includes:

s311, respectively acquiring the printing precision of the reference printing image and the first printing image;

the printing precision comprises the following steps: straightness of connecting lines of all the printed ink drops, diameter variance of all the printed ink drops and flying ink point number of each ink drop;

s312, matching the precision grade corresponding to the printing precision;

the printing accuracy is graded according to the printing condition, for example, the straightness is in a preset range, the variance of the diameter is less than or equal to 4, and the number of points with ink flying is less than or equal to 4, the accuracy grade is set to pass.

And S313, taking the precision grade as a preliminary evaluation result.

The grade of the printing precision comprises pass and fail, and when the grade of the printing precision is pass, the driving waveform used at the temperature point is determined.

Preferably, the obtaining the printing accuracies of the reference print image and the first print image respectively includes:

respectively establishing a coordinate system which is in the same plane with the reference printing image and the first printing image; a row of nozzles of the nozzle head is controlled to jet ink once according to certain ink jet parameters under a driving waveform, and a row of dot patterns are formed on a printing medium. And acquiring a dot diagram by adopting a high-definition high-multiple image acquisition device to obtain an ink dot image for subsequent analysis. Acquiring coordinate information of each ink dot in the ink dot image in the coordinate system;

respectively acquiring coordinate information of each ink drop in the reference printing image and the first printing image in the coordinate system; the coordinate information of the dots includes: outline information of the dots and center coordinates of the dots. Because the ink dots can permeate on the printing medium and some fuzzy outlines can appear, the ink dot image is processed to a certain extent to obtain the center coordinates of the ink dots.

Calculating the characteristic information of the reference printing image and the first printing image according to the coordinate information corresponding to each ink drop; and according to the characteristic information of the ink dot image of the ink dots, including at least one of the number of satellite dots, the printing straightness of the ink dots and the uniformity of the size of the ink dots of all the ink dots in the ink dot image. The characteristic information can intuitively reflect the printing precision problem.

And respectively comparing the reference printing image and the first printing image characteristic information with preset conditions to obtain comparison results, and judging the printing precision according to the comparison results. Each kind of ink dot characteristic information corresponds to a range, and if the ink dot characteristic information is not in the range, the printing precision is considered to be unqualified. Or dividing the printing precision according to a certain grade, and performing corresponding matching according to the ink dot characteristic information to obtain the grade of the printing precision.

In this embodiment, the feature information of the dot image is feature information expressed by all dots on the dot image, and includes: at least one of the number of satellite dots, the printing straightness of the ink dots, and the uniformity of the size of the ink dots.

The satellite dots are the ink droplets ejected from the nozzles, which are scattered under the influence of the pressure of the environment, the flow of air, and the like during the movement, and the ink droplets are scattered on the printing medium, specifically, a positive dot is formed by the falling dots on the printing medium, and small dots are formed around the positive dot, and these small dots are called satellite dots. As shown in fig. 5, if there are N main dots in one dot image and there are satellite dots, the number of satellite dots in this dot image is N. The satellite dots mean that other small dots are present around one dot in the lateral direction, or that more than one dot is present at one dot position, in which case the size difference of the dots from the same row is large. The number of satellite dots is defined according to the number of abnormal ink dots.

In addition, when one positive dot only has one satellite dot, the judgment of the satellite dot comprises the steps of acquiring the area of the dots formed by all ink drops, calculating the average area of all the dots, and judging the corresponding dot as the satellite dot if the area is less than 50% of the average area.

If one positive point corresponds to one or more satellite points, the judgment of the satellite points comprises the following steps: acquiring all ink points corresponding to a single nozzle, calculating the areas of all the ink points, defining the ink point with the largest area as a positive point and defining the ink point with the smaller area as a satellite point.

When the areas of all the dots corresponding to a single nozzle are the same, a dot close to the reference line is defined as a positive dot, and a dot farther from the reference line is defined as a satellite dot. The larger dots are called positive dots and the small dots distributed around the positive dots are satellite dots.

In this embodiment, coordinate information corresponding to dots is found by establishing a coordinate system, and feature information of a dot image that can reflect printing accuracy is calculated; and comparing the characteristic information with a preset condition to obtain the printing precision. The invention provides a uniform standard for printing precision, and adopts a scientific calculation method to calculate the characteristic information of the ink dot image and judge the printing precision, thereby reducing the artificial participation and improving the reliability of precision judgment; the method has the effect of quickly and accurately judging the printing precision.

Preferably, the reference printing image is an image formed by driving the nozzle to jet ink droplets of a specified ink volume once at a reference temperature by using a preset driving waveform; the first print image is an image formed by driving the nozzle to eject ink droplets of the specified ink volume once at a first temperature using the preset driving waveform.

The second print image is also an image formed with ink droplets that are ejected with a specified ink amount at one time by driving the heads at the alternative waveform. That is, all images are dot images formed with one ink droplet.

Example two

The second embodiment is an improvement on the first embodiment, and additionally explains the judgment of the printing precision, and provides a method for judging the printing precision, which is applied to a printing device and judges the printing precision. The printing precision can be fine and reflect the influence of each printing parameter of the printing equipment on the printing effect, for example, the influence of the driving waveform on the printing effect, and the printing precision can intuitively reflect whether the driving waveform is suitable for printing at the temperature. As shown in fig. 6, the method includes:

s1, acquiring a dot image formed by jetting once on a printing medium by a nozzle (the step corresponds to the first embodiment that the reference printing image is an image formed by jetting once a specified ink amount of ink drops by driving a nozzle with a preset driving waveform at a reference temperature; the first printing image is an image formed by jetting once the specified ink amount of ink drops by driving the nozzle with the preset driving waveform at a first temperature);

a row of nozzles of the nozzle head is controlled to jet ink once according to certain ink jet parameters under a driving waveform, and a row of dot patterns are formed on a printing medium. And acquiring a dot diagram by adopting a high-definition high-multiple image acquisition device to obtain an ink dot image for subsequent analysis.

S2, establishing a coordinate system in the same plane as the dot image (this step corresponds to the embodiment in which the coordinate system in the same plane as the reference print image and the first print image are respectively established);

a two-dimensional coordinate system is established on a plane where the ink dots are located, so that all the ink dots are in the coordinate system.

S3, acquiring coordinate information of each dot in the dot image in the coordinate system (this step corresponds to acquiring coordinate information of each ink droplet in the reference print image and the first print image in the coordinate system respectively);

the coordinate information of the dots includes: outline information of the dots and center coordinates of the dots. Because the ink dots can permeate on the printing medium and some fuzzy outlines can appear, the ink dot image is processed to a certain extent to obtain the center coordinates of the ink dots.

S4, calculating the characteristic information of the ink dot image according to the coordinate information corresponding to each ink dot (in the first embodiment, calculating the characteristic information of the reference printing image and the first printing image according to the coordinate information corresponding to each ink drop);

and according to the characteristic information of the ink dot image of the ink dots, including at least one of the number of satellite dots, the printing straightness of the ink dots and the uniformity of the size of the ink dots of all the ink dots in the ink dot image. The characteristic information can intuitively reflect the printing precision problem.

And S5, comparing the dot image feature information with a preset condition to obtain a comparison result, and judging the printing precision according to the comparison result (in the first embodiment, comparing the reference printing image and the first printing image feature information with the preset condition to obtain the comparison result, and judging the printing precision according to the comparison result).

Each kind of ink dot characteristic information corresponds to a range, and if the ink dot characteristic information is not in the range, the printing precision is considered to be unqualified. Or dividing the printing precision according to a certain grade, and performing corresponding matching according to the ink dot characteristic information to obtain the grade of the printing precision.

In this embodiment, the feature information of the dot image is feature information expressed by all dots on the dot image, and includes: at least one of the number of satellite dots, the printing straightness of the ink dots, and the uniformity of the size of the ink dots. The satellite dots are the ink droplets ejected from the nozzles, which are scattered under the influence of the pressure of the environment, the flow of air, and the like during the movement, and the ink droplets are scattered on the printing medium, specifically, a positive dot is formed by the falling dots on the printing medium, and small dots are formed around the positive dot, and these small dots are called satellite dots. As shown in fig. 10, if there are N main dots in one dot image and there are satellite dots, the number of satellite dots in this dot image is N. The satellite dots mean that other small dots are present around one dot in the lateral direction, or that more than one dot is present at one dot position, in which case the size difference of the dots from the same row is large. The number of satellite dots is defined according to the number of abnormal ink dots.

When the areas of all the dots corresponding to a single nozzle are the same, a dot close to the reference line is defined as a positive dot, and a dot farther from the reference line is defined as a satellite dot. As shown in fig. 10, the larger dots are referred to as positive dots, and the small dots distributed around the positive dots are satellite dots.

As shown in fig. 7, comparing the dot image feature information with a preset condition to obtain a comparison result, and determining the printing accuracy according to the comparison result includes:

s41, processing the coordinate information corresponding to all the ink dots to obtain a reference line;

and performing linear fitting on the coordinate information corresponding to all the ink points to obtain a datum line, wherein the datum line is a linear equation of two-dimensional on a two-dimensional coordinate system. Namely, the central coordinates of each ink dot are fitted to obtain a linear equation of two.

S42, calculating the variance of each ink point from the reference line;

FIG. 9 shows all dots aligned along the x-axis. The absolute value of the actual y value of the dot corresponding to the y value on the reference line for the same x value as the dot is calculated. The absolute length is the offset of the dot from the reference line.

And S43, taking the variance as characteristic information.

The variance is the offset of each dot from the reference line.

Preferably, the step of processing the coordinate information corresponding to all the dots to obtain the reference line includes: and performing linear fitting on the coordinate information corresponding to all the ink points to obtain a linear equation of the reference line.

In the present embodiment, in the above-described step S41, the variance is calculated from the univariate linear regression model.

The linear regression equation is:

y＝α+βx

according to the rule of Cramer, get solutions

And

and (3) calculating: variance σ²

Wherein the content of the first and second substances,

it is determined whether the variance is less than 20. If the variance is larger than 20, judging that the printing straightness of the ink dots is unqualified, namely the printing precision is unqualified; the variance is less than or equal to 20, and the printing straightness of the ink dots is judged to be qualified. If the printing precision is judged to be qualified, the offset of the ink dots ejected under the driving waveform meets the preset requirement, and the printing precision of all the nozzles meets the requirement.

Preferably, as shown in fig. 8, comparing the dot image feature information with a preset condition to obtain a comparison result, and determining the printing accuracy according to the comparison result includes:

s44, acquiring contour coordinate information of each ink dot;

since ink printed on a printing medium has bleeding and the edges of the ink have no distinct boundary, there is no way to directly obtain clear contour information, and therefore more accurate contour coordinate information needs to be obtained.

The step of acquiring contour coordinate information of each dot further comprises the following steps: and acquiring the ink dot outline information of the ink dot image under a preset tolerance value.

Tolerance represents the approximation degree when similar color selection is selected, the preset tolerance value is 30, and the contour information of the selected ink dots is clicked. At a certain tolerance value, the boundary that can be clearly confirmed is used as the outline information of the ink dot. And confirming the contour information of all the ink dots under the same tolerance.

S45, calculating the diameter of the corresponding ink dot according to the contour coordinate information of each ink dot;

the image formed by the ink drop falling on the printing medium should be a smooth dot, so that the outline information of the dot can be confirmed, if the dot is not sufficiently round, the outline of the dot is smoothed to obtain an approximate circle, and further, the outline information of the round dot can be obtained. It is also possible to obtain the width value w of the ink dot for simplicity_iAnd height value h_i. Thus, the diameter of the dot can be directly obtained.

S46, calculating the diameter variance of all the ink dots according to the diameter of each ink dot;

and S47, taking the diameter variance as characteristic information.

In the above step S46, all the dot diameters are added and then the diameters of all the dots are averaged.

Diameter of each dot:

the diameters of all dots are added to give the average diameter of the dots:

variance of dot diameter

The variance can directly reflect the degree of dot uniformity; and judging whether the variance of the diameter is less than or equal to 4, and if the variance is more than 4, determining that the uniformity of the size of the ink dot is qualified.

Preferably, the step of calculating the relevant parameter according to the coordinate information corresponding to each dot includes:

acquiring the number of ink flying points in a preset range of each ink dot;

defining the number of flying ink points as related parameters.

In this embodiment, it is determined whether there are dots around the dot, or whether there are satellite dots in the direction perpendicular to the nozzle row for each dot, and if the number of dots in which there are satellite dots is greater than 4, it is determined that the printing accuracy does not meet the requirement; the condition that the printing precision meets the requirement is that under the driving of the driving waveform, the ejected ink drop does not have ink flying, namely, satellite dots do not occur.

In this embodiment, the step of acquiring coordinate information of each dot on the coordinate system before the dot image further includes: judging whether satellite points exist or not; and if the satellite points exist, discarding the coordinate information of the satellite points. Specifically, the area of dots formed by all ink droplets is acquired, and specifically, the average area of each dot may be calculated based on the contour information of the dots acquired in the above step. And then calculating the average area of all the points, wherein the area is less than 50% of the average area, and then determining the corresponding points as satellite points. After the step of determining the satellite dot, if the dot is regarded as the satellite dot, the coordinate information of the ink dot is not conformed. Thus, when the satellite spot falls on the position of the line formed by connecting all the spots, there is a variance in the confirmation reference line. According to the arrangement, only the large points are determined as the points participating in linear fitting, so that the judgment precision of the reference line is improved, and the standard of printing precision judgment is improved.

Preferably, the step of acquiring the dot image formed once by the nozzle jetting on the printing medium includes:

acquiring an original image formed by jetting a nozzle on a printing medium once; and amplifying the original image to obtain the ink dot image.

In this embodiment, a high magnification magnifier is used to magnify the original image; then shooting the amplified image by using a high-definition camera; and amplifying the original image to obtain a higher-definition image, so that the printing precision can be conveniently confirmed.

EXAMPLE III

The third embodiment of the invention provides a device for judging printing precision, which is applied to printing equipment and used for judging the printing precision. The printing precision can be fine and reflect the influence of each printing parameter of the printing equipment on the printing effect, for example, the influence of the driving waveform on the printing effect, and the printing precision can intuitively reflect whether the driving waveform is suitable for printing at the temperature. As shown in fig. 11, the apparatus includes:

a first acquiring module 1 that acquires a dot image formed by jetting a nozzle on a printing medium at one time;

a row of nozzles of the head is controlled to eject ink once according to a certain ink ejection parameter under a driving waveform, and a row of dot patterns is formed on the printing medium. And acquiring a dot diagram by adopting a high-definition high-multiple image acquisition device to obtain an ink dot image for subsequent analysis.

The establishing module 2 is used for establishing a coordinate system which is positioned on the same plane with the ink dot image;

The second acquisition module 3 is used for acquiring the coordinate information of each ink dot in the ink dot image in the coordinate system;

The calculating module 4 is used for calculating the characteristic information of the ink dot image according to the coordinate information corresponding to each ink dot;

And the judging module 5 obtains the printing precision according to the related parameters.

In this embodiment, the feature information of the dot image is feature information expressed by all dots on the dot image, and includes: at least one of the number of satellite dots, the printing straightness of the ink dots, and the uniformity of the size of the ink dots. The satellite dots are the ink droplets ejected from the nozzles, which are scattered under the influence of the pressure of the environment, the flow of air, and the like during the movement, and the ink droplets are scattered on the printing medium, specifically, a positive dot is formed by the falling dots on the printing medium, and small dots are formed around the positive dot, and these small dots are called satellite dots. If N positive dots exist in one ink dot image, the number of satellite dots in the ink dot image is N. The satellite dots mean that other small dots are present around one dot in the lateral direction, or that more than one dot is present at one dot position, in which case the size difference of the dots from the same row is large. The number of satellite dots is defined according to the number of abnormal ink dots.

When the areas of all the dots corresponding to a single nozzle are the same, a dot close to the reference line is defined as a positive dot, and a dot farther from the reference line is defined as a satellite dot.

Preferably, the computing module is further configured to process coordinate information corresponding to all the dots to obtain a reference line; calculating the variance of each ink point from the reference line; defining the variance as the feature information.

The absolute value of the actual y value of the dot corresponding to the y value on the reference line for the same x value as the dot is calculated.

The variance is the offset of each dot from the reference line.

In this embodiment, the variance is calculated according to a univariate linear regression model.

The linear regression equation is:

y＝α+βx

according to the rule of Cramer, get solutions

And

and (3) calculating: variance σ²

Wherein the content of the first and second substances,

Preferably, the calculation module is further configured to obtain contour coordinate information of each dot; calculating the diameter of the corresponding ink dot according to the contour coordinate information of each ink dot; calculating the diameter variance of all the ink dots according to the diameter of each ink dot; defining the diameter variance as the characteristic information.

Since ink bleeding occurs when printed on a print medium, the edges of the ink do not have a distinct boundary, which results in no way of directly obtaining unambiguous contour information.

Therefore, preferably, the step of acquiring contour coordinate information of each dot further includes: and acquiring the ink dot outline information of the ink dot image under a preset tolerance value.

Tolerance represents the approximation degree when similar color selection is selected, the preset tolerance value is 30, and the contour information of the selected ink dots is clicked. Under a certain tolerance value, the boundary which can be obviously confirmed is used as the outline information of the ink dot. And confirming the contour information of all the ink dots under the same tolerance.

The image formed by the ink drop falling on the printing medium should be a round dot, so that the outline information of the dot can be confirmed, if the dot is not round enough, the outline of the dot is smoothed to obtain an approximate circle, and further the outline information of the round dot can be obtained. It is also possible to obtain the width value w of the ink dot for simplicity_iAnd height value h_i. Thus, the diameter of the dot can be directly obtained.

All dot diameters are summed and then averaged.

Diameter of each dot:

the diameters of all dots are added to give the average diameter of the dots:

variance of dot diameter

The variance can directly reflect the degree of dot uniformity; and judging whether the variance is less than or equal to 4, and if the variance is more than 4, determining that the uniformity of the ink dot size is qualified.

acquiring the number of ink flying points in a preset range of each ink dot;

defining the number of flying ink points as related parameters.

In this embodiment, the step of acquiring coordinate information of each dot with respect to the coordinate system further includes: judging whether satellite points exist or not; and if the satellite points exist, discarding the coordinate information of the satellite points. Specifically, the area of dots formed by all ink droplets is acquired, and specifically, the average area of each dot may be calculated based on the contour information of the dots acquired in the above step. And then calculating the average area of all the points, wherein the area is less than 50% of the average area, and then determining the corresponding points as satellite points. After the step of determining the satellite dot, if the dot is regarded as the satellite dot, the coordinate information of the ink dot is not conformed. Thus, when the satellite spot falls on the position of the line formed by connecting all the spots, there is a variance in the confirmation reference line. According to the arrangement, only the large points are determined as the points participating in linear fitting, so that the judgment precision of the reference line is improved, and the standard of printing precision judgment is improved.

Example four

The method for judging the printing accuracy in the second embodiment of the present invention described with reference to fig. 12 is implemented by a printing apparatus. Fig. 12 is a schematic diagram illustrating a hardware configuration of a printing apparatus according to an embodiment of the present invention.

The area printing device may include a processor 301 and a memory 302 storing computer program instructions.

In particular, the processor 301 may include a central processing unit 301(CPU), or an Application Specific Integrated Circuit (ASIC), or may be configured as one or more Integrated circuits implementing embodiments of the present invention.

Memory 302 may include mass storage 302 for data or instructions. By way of example, and not limitation, memory 302 may include a Hard Disk Drive (HDD), floppy Disk Drive, flash memory, optical Disk, magneto-optical Disk, magnetic tape, or Universal Serial Bus 310 (USB) Drive or a combination of two or more of these. Memory 302 may include removable or non-removable (or fixed) media, where appropriate. The memory 302 may be internal or external to the data processing apparatus, where appropriate. In a particular embodiment, the memory 302 is non-volatile solid-state memory 302. In a particular embodiment, the memory 302 includes read only memory 302 (ROM). Where appropriate, the ROM may be mask-programmed ROM, Programmable ROM (PROM), Erasable PROM (EPROM), Electrically Erasable PROM (EEPROM), electrically rewritable ROM (EAROM), or flash memory or a combination of two or more of these.

The processor 301 realizes any one of the above-described methods of determining printing accuracy by reading and executing computer program instructions stored in the memory 302.

In one example, the zone printing device may also include a communication interface 303 and a bus 310. As shown in fig. 10, the processor 301, the memory 302, and the communication interface 303 are connected via a bus 310 to complete communication therebetween.

The communication interface 303 is mainly used for implementing communication between modules, apparatuses, units and/or devices in the embodiment of the present invention.

Bus 310 includes hardware, software, or both to couple the components of the zone printing apparatus to each other. By way of example, and not limitation, the bus 310 may include an Accelerated Graphics Port (AGP) or other graphics bus 310, an Enhanced Industrial Standard Architecture (EISA) bus 310, a front side bus 310(FSB), a Hyper Transport (HT) interconnect, an Industrial Standard Architecture (ISA) bus 310, an infiniband interconnect, a Low Pin Count (LPC) bus 310, a memory 302 bus 310, a Micro Channel Architecture (MCA) bus 310, a Peripheral Component Interconnect (PCI) bus 310, a PCI-Express (PCI-X) bus 310, a Serial Advanced Technology Attachment (SATA) bus 310, a video electronics standards association local (VLB) bus 310, or other suitable bus 310, or a combination of two or more of these. Bus 310 may include one or more buses 310, where appropriate. Although specific buses 310 are described and illustrated by embodiments of the invention, the invention contemplates any suitable buses 310 or interconnects.

In addition, in combination with the method for determining printing accuracy in the above embodiments, the embodiments of the present invention may be implemented by providing a computer-readable storage medium. The computer readable storage medium having stored thereon computer program instructions; the computer program instructions, when executed by the processor 301, implement any of the methods of determining printing accuracy in the above embodiments.

It is to be understood that the invention is not limited to the precise arrangements and instrumentalities shown in the drawings and described above. A detailed description of known methods is omitted herein for the sake of brevity. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present invention are not limited to the specific steps described and illustrated, and those skilled in the art can make various changes, modifications and additions or change the order between the steps after comprehending the spirit of the present invention.

The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, plug-in, function card, or the like. When implemented in software, the elements of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted by a data signal carried in a carrier wave over a transmission medium or a communication link. A "machine-readable medium" may include any medium that can store or transfer information. Examples of a machine-readable medium include electronic circuitry, semiconductor memory 302 devices, ROM, flash memory, Erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, Radio Frequency (RF) links, and so forth. The code segments may be downloaded via computer networks such as the internet, intranet, etc.

It should also be noted that the exemplary embodiments mentioned in this patent describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above-described steps, that is, the steps may be performed in the order mentioned in the embodiments, may be performed in an order different from the order in the embodiments, or may be performed simultaneously.

As described above, only the specific embodiments of the present invention are provided, and it can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system, the module and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again. It should be understood that the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for determining printing accuracy, the method comprising:

acquiring a dot image formed by jetting the ink on a printing medium once by a nozzle;

establishing a coordinate system which is positioned on the same plane with the ink dot image;

acquiring coordinate information of each ink dot in the ink dot image in the coordinate system;

calculating the characteristic information of the ink dot image according to the coordinate information corresponding to each ink dot;

and comparing the characteristic information of the ink dot image with preset conditions to obtain a comparison result, and judging the printing precision according to the comparison result.

2. The method for determining printing accuracy according to claim 1, wherein said calculating the characteristic information of said dot image based on the coordinate information corresponding to each dot:

processing coordinate information corresponding to all ink dots in the ink dot image to obtain a reference line;

calculating the variance of each ink point in the ink point image from the reference line;

and taking the variance as the feature information.

3. The method for determining printing accuracy according to claim 2, wherein the step of processing the coordinate information corresponding to all the dots to obtain the reference line comprises: and performing linear fitting on the coordinate information corresponding to all the ink points to obtain a linear equation of the reference line.

4. The method for determining printing accuracy according to claim 1, wherein the step of calculating the feature information of the dot image based on the coordinate information corresponding to each dot includes:

acquiring contour coordinate information of each ink dot;

calculating the diameter of the corresponding ink dot according to the contour coordinate information of each ink dot;

calculating the diameter variance of all the ink dots according to the diameter of each ink dot;

and taking the diameter variance as the characteristic information.

5. The method of determining printing accuracy according to claim 1, wherein said step of acquiring contour coordinate information of each dot is preceded by the step of:

and acquiring the ink dot outline information of the ink dot image under a preset tolerance value.

6. The method for determining printing accuracy according to claim 1, wherein the step of calculating the feature information of the dot image based on the coordinate information corresponding to each dot includes:

acquiring the number of ink flying points in a preset range of each ink dot;

and taking the number of the ink flying points as the characteristic information.

7. The method of judging printing accuracy according to any one of claims 1 to 6, wherein the step of acquiring the dot image formed by ejecting the nozzle on the printing medium once includes:

acquiring an original image formed by jetting a nozzle on a printing medium once;

and amplifying the original image to obtain the ink dot image.

8. An apparatus for judging printing accuracy, the apparatus comprising:

the first acquisition module acquires a dot image formed by jetting the nozzle on the printing medium once;

the establishing module is used for establishing a coordinate system which is positioned on the same plane with the ink dot image;

the second acquisition module is used for acquiring the coordinate information of each ink dot in the ink dot image in the coordinate system;

the computing module is used for computing the characteristic information of the ink dot image according to the coordinate information corresponding to each ink dot;

and the judging module is used for comparing the characteristic information of the ink dot image with preset conditions to obtain a comparison result and judging the printing precision according to the comparison result.

9. A printing apparatus, comprising: at least one processor, at least one memory, and computer program instructions stored in the memory that, when executed by the processor, implement the method of any of claims 1-7.

10. A storage medium having computer program instructions stored thereon, which when executed by a processor implement the method of any one of claims 1-7.