Optimization method and optimization system for quickly checking ink jet state of jet hole through camera

Abstract

The invention discloses an optimization method and optimization system for quickly checking the ink jet state of a spray orifice through a camera, and the method comprises the steps: carrying out the ink droplet observation and positioning of a spray head for ink jet printing, selecting a proper spray head for ink jet printing as a qualified spray head, and carrying out the detection of the ink jet state of the spray orifice through the camera. Recording the parameters of the ink droplets currently sprayed on the test film by the qualified spray head; an ink droplet image on the test film is obtained, interference ink dots in the ink droplet image are filtered out through an ink droplet distribution state and form screening method, a filtered screened ink droplet image is obtained, and the hole position of the abnormal spray hole corresponding to the abnormal ink droplet is checked out through the ink droplet distribution state and form screening method; and carrying out ink droplet observation and measurement on the screened abnormal spray holes. The invention discloses an optimization method and an optimization system for quickly checking the ink jet state of a spray hole through a camera, which minimize interference, increase the robustness of an algorithm and save the time and efficiency for checking the state of a spray head.

Description

Technical Field

[0001] The present invention relates to the technical field of inkjet printing, and in particular to an optimization method and an optimization system for quickly checking the inkjet state of a nozzle through a camera. Background Art

[0002] In the industrial printing industry, due to the large number of nozzles in the printhead, in order to ensure the consistency of the printing state and prevent abnormal printing quality caused by nozzle blockage, it is necessary to visually manage the inkjet state of the nozzle. The existing general method is to accurately collect the speed / volume and angle of the ink droplets of the nozzle through the ink droplet observation instrument. In order to obtain more accurate measurement results, a high-power lens is required, which makes the field of view of the ink droplet observation instrument smaller. At most 5 to 8 nozzles can be inspected each time. A nozzle has thousands of nozzles. If it is checked by mobile inspection, a single nozzle takes about 30 minutes to 1 hour, which greatly affects the work efficiency. If a device uses multiple nozzles to combine nozzle groups for printing, the detection time will be doubled.

[0003] Therefore, it is necessary to develop a system to quickly check the inkjet status. First, the ink droplets are printed on a transparent film, and then the transparent film is sampled for visual inspection and the nozzle number is located. Then, the ink droplets are observed for abnormal nozzle numbers. Since the sampling situation is more complicated, the robustness of the algorithm needs to be strengthened. Summary of the invention

[0004] The present invention overcomes the shortcomings of the prior art and provides an optimization method and optimization system for quickly checking the inkjet status of a nozzle through a camera, using the ejected ink droplets to locate whether the nozzle is abnormal and record the abnormal hole position; through image preprocessing, the interference is minimized, and further reduced through automatic area segmentation, and the phenomenon of uneven ink droplet spacing caused by uneven tension of the transparent film itself is optimized, thereby increasing the robustness of the algorithm and saving time and efficiency in nozzle status inspection.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an optimization method for quickly checking the inkjet state of a nozzle through a camera, comprising the following steps: Step 1, observe and locate the ink droplets of the inkjet printing nozzle, select a suitable inkjet printing nozzle as a qualified nozzle, and record the ink droplet parameters currently sprayed on the test film by the qualified nozzle; Step 2, obtaining the ink drop image on the test film in step 1, filtering out interfering ink dots in the ink drop image by ink drop distribution state and morphology screening method, obtaining the filtered screening ink drop image, and finding out the hole position of the abnormal nozzle corresponding to the abnormal ink drop by ink drop distribution state and morphology screening method; Step 3: perform ink droplet observation and measurement on the screened abnormal nozzles.

[0006] In a preferred embodiment of the present invention, the ink droplet observation and positioning comprises the following steps: Step 1.1, determining whether the ink droplets ejected from the nozzle orifice of the nozzle meet the ink droplet requirements set in inkjet printing; Step 1.1.1, when the ink droplets ejected from the nozzle orifice of the nozzle meet the ink droplet requirements set in inkjet printing, jump to step 2; Step 1.1.2, when the ink droplets ejected from the nozzle orifice of the nozzle do not meet the ink droplet requirements set in inkjet printing, collect the next nozzle orifice and repeat step 1.1; Until a nozzle is selected that can spray ink droplets that meet the requirements set in inkjet printing.

[0007] In a preferred embodiment of the present invention, in step 1.1, an ink droplet observer is used to inspect the nozzles of each row of the nozzle in turn, and the volume of the ink droplets ejected from the nozzles is judged to determine whether it meets the preset ink droplet volume requirements. If it meets the requirements, it is judged to be qualified. If the current ink droplet volume is qualified, the operation of step 1.1 is stopped, and the offset of the first ink droplet in the current row is recorded, and then marked in the ink droplet map of the current row according to the recorded point.

[0008] In a preferred embodiment of the present invention, in step 2, obtaining the ink droplet image on the test film in step 1 includes the following steps: The ink droplet image printed on the test film by the nozzle selected in the current step 1 is collected by a grayscale line scan camera.

[0009] In a preferred embodiment of the present invention, the method for screening ink droplet distribution state and morphology comprises the following steps: Step 2.1, for the abnormal interference on the ink drop image, perform a binarization operation through a set threshold, select the corresponding kernel to perform a preliminary removal of the interfering ink dots through an image morphological filtering operation, and obtain a preliminary filtered ink drop image after the interfering ink dots are removed; Step 2.2, take the center point of all ink droplets in the initial filter ink droplet image, sort the Y value of each ink droplet image, and then automatically segment it into several groups of values ​​using a segmentation algorithm based on the sorting results. At this time, each group of ink droplets still contains interference points; Step 2.3, calculate the distance between all points in the group and the center value of each classification cluster. If the distance is greater than the set threshold, it is considered as interference, and the point is deleted from the group. At this time, the ink drop spacing basically eliminates the interference of nozzle missing and scattered ink droplets, and obtains a deep filter ink drop image; Step 2.4, single missing points are checked in the deep filter ink drop image by using the algorithm for finding single missing points, and single missing points are checked in the deep filter ink drop image by using the algorithm for finding continuous missing points; until the image corresponding point coordinates of all nozzles in this row are found and the serial numbers are marked.

[0010] In a preferred embodiment of the present invention, in step 2.2, the segmentation algorithm includes the following steps: Step 2.2.1, the pixel value of the sample point in the Y direction in the image is marked as Y i , where i represents the number of samples, for Y i The same values ​​are combined and recorded as Y n , where n represents the number of Y samples after merging, the number of records; Step 2.2.2, after merging Y n Dynamically partition clusters, when Y n -Y n-1 =1, the two coordinates are considered adjacent and classified into the same cluster. When Yn-Yn-1>1, the two coordinates are considered not adjacent and classified into different clusters. Each cluster is denoted by C m , M represents the number of clusters, and the mean A of all points in the cluster is calculated m and the number N m ; Step 2.2.3, select the three clusters with the largest number of points; Step 2.2.4: Take the mean of the centers of adjacent clusters to calculate the dividing line value S between clusters m =(A m +A m+1 ) / 2; Step 2.2.5: The original sample is divided into two groups according to the segmentation line value S. m to split.

[0011] In a preferred embodiment of the present invention, the algorithm for finding a single missing point includes the following steps: Calculate the distance D between two adjacent points in the X direction of each group of points i , and the spacing D i Sort and generate D i ', for D i 'Take the median value D i '(I / 2), get the median value of the spacing as the actual ink drop spacing D = D i '(I / 2), I is the number of all samples; Draw a circle with a set radius as the center by adding a standard spacing D to the right of the current point. Search for ink dots from all the points in each group above in the area inside the circle. If they exist, they are determined to be normal ink dots. Search for ink dots to the right based on the currently found ink dots.

[0012] In a preferred embodiment of the present invention, an algorithm for finding consecutive missing ink dots includes the following steps: when a number of adjacent ink droplets are detected as missing dots, the hole positions are corrected again with reference to the results of the adjacent front and back rows; and by analogy, the image corresponding point coordinates of all nozzles in this row are found and the serial numbers are marked.

[0013] The correction of the hole position is based on the characteristics of the nozzle holes of the nozzle, and it is known that the projection intervals of all holes in an ideal state are equal.

[0014] In a preferred embodiment of the present invention, abnormal interference includes ink droplet scatter, ink droplet scratch, or ink droplet adhesion; the nucleus is smaller than a normal ink droplet and larger than the middle value of the ink droplet scatter; and normal ink droplets cannot be removed when the interfering ink dots are initially removed.

[0015] In a preferred embodiment of the present invention, an optimization system for quickly checking the inkjet state of a nozzle through a camera is implemented by an optimization method for quickly checking the inkjet state of a nozzle through a camera, comprising: A data acquisition module, the data acquisition module is used to observe and locate ink droplets of inkjet printing nozzles, select a suitable inkjet printing nozzle as a qualified nozzle, and record the parameters of ink droplets currently sprayed on the test film by the qualified nozzle; A data processing module, the data processing module is used to obtain an ink drop image on the test film, filter out interfering ink dots in the ink drop image by ink drop distribution state and morphology screening method, obtain the filtered screened ink drop image, and identify the hole position of the abnormal nozzle corresponding to the abnormal ink drop by the ink drop distribution state and morphology screening method; A data compound module is used to observe and measure ink droplets on the screened abnormal nozzles.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses an optimization method and an optimization system for quickly checking the inkjet state of a nozzle through a camera.

[0017] 1. The present invention uses a line scan camera image acquisition system, uses a transparent film as an intermediate carrier, uses the ejected ink droplets to locate whether the nozzle hole is abnormal, and records the abnormal hole position.

[0018] 2. In this system, the interference of scattered points / scratches / adhesions is minimized through image preprocessing and further reduced through automatic region segmentation.

[0019] 3. The algorithm in this system enhances the image interference of scattered points / scratches / adhesions. At the same time, the dynamic spacing segmentation method is used to optimize the uneven ink drop spacing caused by the uneven tension of the transparent film, thereby increasing the robustness of the algorithm.

[0020] 4. After positioning, the ink droplet observation instrument is used for precise re-testing, which greatly saves the time and efficiency of the nozzle status inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0022] Figure 1 It is a flow chart of an optimization method and an optimization system for quickly checking the inkjet state of a nozzle through a camera according to the present invention; Figure 2 It is a schematic diagram of an optimization method for quickly checking the inkjet state of a nozzle through a camera and ink droplet observation and positioning in an optimization system of the present invention; Figure 3 It is a schematic diagram of an optimization method for quickly checking the inkjet state of a nozzle through a camera and a nozzle in an optimization system spraying ink droplets onto a test film; Figure 4 It is a schematic diagram of an optimization method for quickly checking the inkjet state of a nozzle through a camera of the present invention and an ink droplet image of an ink droplet on a test film collected by a grayscale line scan camera in the optimization system; Figure 5 It is a schematic diagram of an optimization method for quickly checking the inkjet state of a nozzle through a camera and an ink droplet distribution state and morphology screening method in an optimization system to identify the hole position of an abnormal nozzle corresponding to an abnormal ink droplet of the present invention; Figure 6 It is a schematic diagram of an optimization method for quickly checking the inkjet state of a nozzle through a camera and checking the nozzles in sequence in an optimization system of the present invention; Figure 7 It is an optimization method for quickly checking the inkjet state of a nozzle through a camera and an image of ink drop sampling on a test film using a single grayscale line scan camera and a backlight method in the optimization system of the present invention; Figure 8 It is an optimization method for quickly checking the inkjet state of a nozzle through a camera and an image obtained by binarizing a sampled image in an optimization system of the present invention; Fig. 9 It is an optimization method for quickly checking the inkjet state of a nozzle through a camera and an image after the binarization processing is image-processed in the optimization system of the present invention; Fig.10 It is a diagram 1 of an optimization method for quickly checking the inkjet state of a nozzle through a camera and a segmentation algorithm implemented in an optimization system of the present invention; Fig.11 It is a diagram 2 of an optimization method for quickly checking the inkjet state of a nozzle through a camera and a segmentation algorithm implemented in an optimization system of the present invention; Fig.12 The invention relates to an optimization method for quickly checking the inkjet state of a nozzle through a camera and an optimization system for segmenting an original sample according to a segmentation line value Sm to obtain an actual corresponding original image; Fig.13It is a data table after deleting interference points whose distances between all points in the group and the center values ​​of their respective classification clusters are greater than a set threshold value in an optimization method and an optimization system for quickly checking the inkjet state of a nozzle through a camera of the present invention; Fig.14 It is an optimization method for quickly checking the inkjet state of a nozzle through a camera of the present invention and an image after the ink drop spacing in the optimization system is preliminarily removed from the interference of nozzle missing and scattered ink droplets; Fig.15 It is a schematic diagram of an optimization method for quickly checking the inkjet state of a nozzle through a camera and an algorithm for finding a single missing point in the optimization system of the present invention; Fig.16 It is a schematic diagram of an optimization method for quickly checking the inkjet state of a nozzle through a camera and an algorithm for finding consecutive missing ink dots in an optimization system of the present invention; Among them, 1-print head, 2-ink droplet observation instrument, 3-backlight source, 4-grayscale line scan camera, 5-test film, 6-coaxial light source. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0024] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship. Embodiment 1

[0025] like Figure 1-Figure 16 As shown, the present invention discloses an optimization method for quickly checking the inkjet state of a nozzle through a camera, comprising the following steps: Step 1, observe and locate the ink droplets of the inkjet printing nozzle 1, select a suitable inkjet printing nozzle 1 as a qualified nozzle 1, and record the ink droplet parameters currently sprayed by the qualified nozzle 1 on the test film 5; Specifically, the ink droplet observation and positioning includes the following steps: Step 1.1, determining whether the ink droplets ejected from the nozzle hole of the nozzle 1 meet the ink droplet requirements set in inkjet printing; Step 1.1.1, when the ink droplets ejected from the nozzle hole of nozzle 1 meet the ink droplet requirements set in inkjet printing, jump to step 2; Step 1.1.2, when the ink droplets ejected from the nozzle hole of nozzle 1 do not meet the ink droplet requirements set in inkjet printing, collect the next nozzle hole and repeat step 1.1; Until a nozzle 1 that can eject ink droplets that meet the requirements set in inkjet printing is selected.

[0026] More specifically, in step 1.1, an ink droplet observer 2 is used to inspect the nozzles of each row of the nozzle 1 in turn, and the volume of the ink droplets ejected from the nozzles is determined to determine whether it meets the preset ink droplet volume requirement. If it meets the requirement, it is determined to be qualified. If the current ink droplet volume is qualified, the operation of step 1.1 is stopped, and the offset of the first ink droplet in the current row is recorded, and then marked in the ink droplet map of the current row according to the recorded point.

[0027] Step 2, obtain the ink drop image on the test film 5 in step 1, filter out the interfering ink dots in the ink drop image by ink drop distribution state and morphology screening method, obtain the filtered screened ink drop image, and find out the abnormal nozzle hole position corresponding to the abnormal ink drop by ink drop distribution state and morphology screening method. Abnormal interference includes ink drop scatter, ink drop scratch, or ink drop adhesion; the core is smaller than the normal ink drop and larger than the middle value of the ink drop scatter; normal ink drop cannot be removed when the interfering ink dots are initially removed.

[0028] Specifically, in step 2, obtaining the ink drop image on the test film 5 in step 1 includes the following steps: The grayscale line scan camera 4 captures the ink droplet image of the ink droplet printed on the test film 5 by the nozzle selected in the current step 1 .

[0029] Furthermore, the ink droplet distribution state and morphology screening method includes the following steps: Step 2.1, for the abnormal interference on the ink drop image, perform a binarization operation through a set threshold, select the corresponding kernel to perform a preliminary removal of the interfering ink dots through an image morphological filtering operation, and obtain a preliminary filtered ink drop image after the interfering ink dots are removed; Step 2.2, take the center point of all ink droplets in the initial filtered ink droplet image, and sort the Y value of each ink droplet image, and then use the segmentation algorithm to automatically segment it into several groups of values ​​according to the sorting results. At this time, each group of ink droplets still contains interference points.

[0030] Furthermore, in step 2.2, the segmentation algorithm includes the following steps: Step 2.2.1, the pixel value of the sample point in the Y direction in the image is marked as Y i , where i represents the number of all samples, for Y i The same values ​​are combined and recorded as Y n , where n represents the number of Y samples after merging, the number of records; Step 2.2.2, after merging Y nDynamic partition cluster (heap), when Y n -Y n-1 = 1, the two coordinates are considered adjacent and classified into the same cluster. n -Y n-1 >1, the two coordinates are considered to be non-adjacent and classified into different clusters. Each cluster is denoted by C m , M represents the number of clusters, and the mean A of all points in the cluster is calculated m and the number N m ; Step 2.2.3, select the three clusters with the largest number of points; Step 2.2.4: Take the mean of the centers of adjacent clusters to calculate the dividing line value S between clusters m =(A m +A m+1 ) / 2; Step 2.2.5: The original sample is divided into two groups according to the segmentation line value S. m Segmentation is performed, which actually corresponds to the original image record.

[0031] Step 2.3, calculate the distance between all points in the group and the center value of each classification cluster. If the distance is greater than the set threshold, it is considered as interference, and the point is deleted from the group. At this time, the ink drop spacing basically eliminates the interference of nozzle missing and scattered ink droplets, and obtains a deep filter ink drop image; Step 2.4, single missing points are checked in the deep filter ink drop image by using the algorithm for finding single missing points, and single missing points are checked in the deep filter ink drop image by using the algorithm for finding continuous missing points; until the image corresponding point coordinates of all nozzles in this row are found and the serial numbers are marked.

[0032] Furthermore, the algorithm for finding a single missing point includes the following steps: Calculate the distance D between two adjacent points in the X direction of each group of points i , and the spacing D i Sort and generate D i ', for D i 'Take the median value D i '(I / 2), get the median value of the spacing as the actual ink drop spacing D = D i '(I / 2), I is the number of all samples; according to the current point, add a standard spacing D to the right and draw a circle with a set radius as the center. In the area inside the circle, search for ink dots from all the points in each group above. If they exist, they are judged as normal ink dots. Then search for ink dots to the right according to the currently found ink dots.

[0033] Furthermore, the algorithm for finding consecutive missing ink dots includes the following steps: when a number of adjacent ink drops are detected as missing dots, the hole positions are corrected again with reference to the results of the adjacent front and back rows; and by analogy, the image corresponding point coordinates of all nozzle holes in this row are found and the serial numbers are marked. The hole positions are corrected based on the characteristics of the nozzle holes of nozzle 1, and it is known that the spacing of all holes after projection in the ideal state is equal.

[0034] Step 3: perform ink droplet observation and measurement on the screened abnormal nozzles. Embodiment 2

[0035] like Figure 1-Figure 16 As shown, an optimized method for quickly checking the inkjet state of a nozzle through a camera comprises the following steps: Step 1, observe and locate the ink droplets of the inkjet printing nozzle 1, select a suitable inkjet printing nozzle 1 as a qualified nozzle 1, and record the ink droplet parameters currently sprayed by the qualified nozzle 1 on the test film 5; Specifically, the ink droplet observation and positioning includes the following steps: Step 1.1, determining whether the ink droplets ejected from the nozzle hole of the nozzle 1 meet the ink droplet requirements set in inkjet printing; Step 1.1.1, when the ink droplets ejected from the nozzle hole of nozzle 1 meet the ink droplet requirements set in inkjet printing, jump to step 2; Step 1.1.2, when the ink droplets ejected from the nozzle hole of nozzle 1 do not meet the ink droplet requirements set in inkjet printing, collect the next nozzle hole and repeat step 1.1; Until a nozzle 1 that can eject ink droplets that meet the requirements set in inkjet printing is selected.

[0036] More specifically, in step 1.1, an ink droplet observer 2 is used to inspect the nozzles of each row of the nozzle 1 in turn, and the volume of the ink droplets ejected from the nozzles is determined to determine whether it meets the preset ink droplet volume requirement. If it meets the requirement, it is determined to be qualified. If the current ink droplet volume is qualified, the operation of step 1.1 is stopped, and the offset of the first ink droplet in the current row is recorded, and then marked in the ink droplet map of the current row according to the recorded point.

[0037] For example: by cooperating with the ink droplet observation instrument 2 and the coaxial light source 6 located on both sides of the nozzle 1, each row of nozzle holes is checked in turn, and whether it is qualified is determined according to the volume. If the current ink droplet volume is qualified, the first step of the operation is stopped, and the offset of the first ink droplet in the current row is recorded, and then marked in the figure according to the recorded point position (assuming that the nozzle 1 has 3 rows of nozzle holes, the following results are Gap: 2 for the first row, Gap: 1 for the second row, and Gap: 1 for the third row).

[0038] Step 2, obtain the ink drop image on the test film 5 in step 1, filter out the interfering ink dots in the ink drop image by ink drop distribution state and morphology screening method, obtain the filtered screened ink drop image, and find out the abnormal nozzle hole position corresponding to the abnormal ink drop by ink drop distribution state and morphology screening method. Abnormal interference includes ink drop scatter, ink drop scratch, or ink drop adhesion; the core is smaller than the normal ink drop and larger than the middle value of the ink drop scatter; normal ink drop cannot be removed when the interfering ink dots are initially removed.

[0039] Specifically, in step 2, obtaining the ink drop image on the test film 5 in step 1 includes the following steps: The ink droplet image of the ink droplet printed on the test film 5 by the nozzle selected in the current step 1 is collected by the grayscale line scan camera 4. A backlight source 3 is provided on the lower side of the test film 5, and the test film 5 is a transparent test film. It is convenient to cooperate with the backlight source 3 to improve the accuracy and stability of ink dot sampling.

[0040] Furthermore, the ink droplet distribution state and morphology screening method includes the following steps: Step 2.1, for the abnormal interference on the ink drop image, perform a binarization operation through a set threshold, select the corresponding kernel to perform a preliminary removal of the interfering ink dots through an image morphological filtering operation, and obtain a preliminary filtered ink drop image after the interfering ink dots are removed; Step 2.2, take the center point of all ink droplets in the initial filtered ink droplet image, and sort the Y value of each ink droplet image, and then use the segmentation algorithm to automatically segment it into several groups of values ​​according to the sorting results. At this time, each group of ink droplets still contains interference points.

[0041] Furthermore, in step 2.2, the segmentation algorithm includes the following steps: Step 2.2.1, the pixel value of the sample point in the Y direction in the image is marked as Y i , where i represents the number of all samples, for Y i The same values ​​are combined and recorded as Y n , where n represents the number of Y samples after merging, the number of records; Step 2.2.2, after merging Y n Dynamic partition cluster (heap), when Y n -Y n-1 =1, the two coordinates are considered adjacent and classified into the same cluster. When Yn-Yn-1>1, the two coordinates are considered not adjacent and classified into different clusters. Each cluster is denoted by C m , M represents the number of clusters, and the mean A of all points in the cluster is calculated m and the number N m ; Step 2.2.3, select the three clusters with the largest number of points; Step 2.2.4: Take the mean of the centers of adjacent clusters to calculate the dividing line value S between clusters m =(A m +A m+1 ) / 2; Step 2.2.5: The original sample is divided into two groups according to the segmentation line value S. m Segmentation is performed, which actually corresponds to the original image record.

[0042] Step 2.3, calculate the distance between all points in the group and the center value of each classification cluster. If the distance is greater than the set threshold, it is considered to be interference, and the point is deleted from the group. At this time, the ink drop spacing basically eliminates the interference of nozzle missing and scattered ink droplets, and obtains a deep filter ink drop image.

[0043] For example: Calculate the Y of all points in this group n and the center value A of each classification cluster m The distance D of (62,162,269) n =Y n -A m ,If the distance is greater than the set threshold (assumed to be 10), it is considered as interference, and the point is deleted from the group.

[0044] Step 2.4, single missing points are checked in the deep filter ink drop image by using the algorithm for finding single missing points, and single missing points are checked in the deep filter ink drop image by using the algorithm for finding continuous missing points; until the image corresponding point coordinates of all nozzles in this row are found and the serial numbers are marked.

[0045] Furthermore, the algorithm for finding a single missing point includes the following steps: Calculate the distance D between two adjacent points in the X direction of each group of points i , and the spacing D i Sort and generate D i ', for D i 'Take the median value D i '(I / 2), get the median value of the spacing as the actual ink drop spacing D=D of this group of data i '(I / 2), I is the number of all samples; according to the current point, add a standard spacing D to the right and draw a circle with a set radius as the center. In the area inside the circle, search for ink dots from all the points in each group above. If they exist, they are judged as normal ink dots. Then search for ink dots to the right according to the currently found ink dots.

[0046] For example, when calculating the distance between two adjacent points in the X direction of each group of points, D i =X i -X i-1 (I represents the total number of samples), and the interval D i Sort and generate D i ', for Di 'Take the median value D i '(I / 2), get the median value of the spacing as the actual ink drop spacing D = D i '(I / 2). Draw a circle with a set radius and a standard spacing D to the right of the current point. Search for ink dots from all the points in each group above in the area inside the circle. If they exist, they are determined to be normal ink dots. Search for ink dots to the right according to the currently found ink dots.

[0047] Here is the search process: Assume that the Gap=1 in the second row of observations, sort all the points in the second row of category C2 in the X direction. Because Gap=1, it is assumed that there is no missing starting point, so the point with the minimum X value is marked as X. 21 (Row 2, No. 1); In range Traverse all the points in the second row, if there is a point that meets the range, mark this point as X 22 ; In range Traverse all the points in the second row. If there is no point that satisfies the condition, then point X is considered missing. 23 =X 22 +D; In range Traverse all the points in the second row, if there is a point that meets the range, mark this point as X 24 .

[0048] Furthermore, the algorithm for finding consecutive missing ink dots includes the following steps: when a number of adjacent ink drops are detected as missing dots, the hole positions are corrected again with reference to the results of the adjacent front and back rows; and by analogy, the image corresponding point coordinates of all nozzle holes in this row are found and the serial numbers are marked. The hole positions are corrected based on the characteristics of the nozzle holes of nozzle 1, and it is known that the spacing of all holes after projection in the ideal state is equal.

[0049] For example, when X is detected 23 The first is the missing point, X 24 If there are missing points, you need to refer to the results of the first and third rows to correct the hole positions. 24 =(X 14 +X 34 ) / 2, because of the characteristics of the nozzle holes of nozzle 1, the spacing of all holes after projection is theoretically equal. 24 The first is the missing point, X 25 If X is also a missing point, then 25 =(X 15 +X 35 ) / 2.

[0050] Similarly, find the coordinates of the corresponding points in the image of all nozzles in this row and mark the serial numbers.

[0051] Step 3: perform ink droplet observation and measurement on the screened abnormal nozzles. Embodiment 3

[0052] Based on the first or second embodiment, an optimization system for quickly checking the inkjet state of a nozzle through a camera is implemented by using an optimization method for quickly checking the inkjet state of a nozzle through a camera, including: The data acquisition module is used to observe and locate ink droplets of the inkjet printing nozzle 1, select a suitable inkjet printing nozzle 1 as a qualified nozzle, and record the parameters of the ink droplets currently sprayed on the test film 5 by the qualified nozzle 1.

[0053] A data processing module is used to obtain an ink droplet image on the test membrane 5, filter out interfering ink dots in the ink droplet image through ink droplet distribution status and morphology screening methods, obtain the filtered screened ink droplet image, and identify the abnormal ink droplet corresponding to the abnormal nozzle hole position through ink droplet distribution status and morphology screening methods.

[0054] A data compound module is used to observe and measure ink droplets on the screened abnormal nozzles.

[0055] Working principle: The present invention provides an optimization method and an optimization system for quickly checking the inkjet state of a nozzle through a camera. The ink droplet observation system detects the angular position state of a nozzle 1 to establish a connection between a point on a transparent film and an actual nozzle, and accurately locates the nozzle. The image is binarized and the blob is extracted, and then a morphological opening operation is performed to remove most of the original scattered points / adhesions and film scratch interference, and then the ink droplet rows are automatically segmented according to the Y-direction position distribution state. The nozzle sequence error caused by the uneven ink droplet spacing caused by the warping of the film is solved by dynamically updating the reference point. By referring to the X-direction position of the correct nozzles in other rows, the precise position of the continuous abnormal nozzle sequence when the nozzles in a large area are currently blocked is calculated.

[0056] Based on the ideal embodiment of the present invention, through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. An optimization method for quickly checking the inkjet status of a nozzle through a camera, characterized in that: The following steps are involved: Step 1, observe and locate the ink droplets of the inkjet printing nozzle, select a suitable inkjet printing nozzle as a qualified nozzle, and record the ink droplet parameters currently sprayed on the test film by the qualified nozzle; Step 2, obtaining the ink drop image on the test film in step 1, filtering out interfering ink dots in the ink drop image by ink drop distribution state and morphology screening method, obtaining the filtered screening ink drop image, and finding out the hole position of the abnormal nozzle corresponding to the abnormal ink drop by ink drop distribution state and morphology screening method; Step 3: perform ink droplet observation and measurement on the screened abnormal nozzles.

2. The optimization method for quickly checking the inkjet status of a nozzle through a camera according to claim 1, characterized in that: The ink droplet observation and positioning comprises the following steps: Step 1.1, determining whether the ink droplets ejected from the nozzle orifice of the nozzle meet the ink droplet requirements set in inkjet printing; Step 1.1.1, when the ink droplets ejected from the nozzle orifice of the nozzle meet the ink droplet requirements set in inkjet printing, jump to step 2; Step 1.1.2, when the ink droplets ejected from the nozzle orifice of the nozzle do not meet the ink droplet requirements set in inkjet printing, collect the next nozzle orifice and repeat step 1.1; Until a nozzle is selected that can spray ink droplets that meet the requirements set in inkjet printing.

3. The optimization method for quickly checking the inkjet status of a nozzle through a camera according to claim 2, characterized in that: In step 1.1, an ink droplet observer is used to check the nozzles of each row of the nozzles in turn, and the volume of the ink droplets ejected from the nozzles is used to determine whether it meets the preset ink droplet volume requirements. If it meets the requirements, it is determined to be qualified. If the current ink droplet volume is qualified, the operation of step 1.1 is stopped, and the offset of the first ink droplet in the current row is recorded, and then marked in the ink droplet map of the current row according to the recorded point.

4. The optimization method for quickly checking the inkjet status of a nozzle through a camera according to claim 3, characterized in that: In step 2, obtaining the ink droplet image on the test film in step 1 includes the following steps: The ink droplet image printed on the test film by the nozzle selected in the current step 1 is collected by a grayscale line scan camera.

5. The optimization method for quickly checking the inkjet status of a nozzle through a camera according to claim 4, characterized in that: The ink droplet distribution state and morphology screening method comprises the following steps: Step 2.1, for the abnormal interference on the ink drop image, perform a binarization operation through a set threshold, select the corresponding kernel to perform a preliminary removal of the interfering ink dots through an image morphological filtering operation, and obtain a preliminary filtered ink drop image after the interfering ink dots are removed; Step 2.2, take the center point of all ink droplets in the initial filter ink droplet image, sort the Y value of each ink droplet image, and then automatically segment it into several groups of values ​​using a segmentation algorithm based on the sorting result. At this time, each group of ink droplets still contains interference points; Step 2.3, calculate the distance between all points in the group and the center value of each classification cluster. If the distance is greater than the set threshold, it is considered as interference, and the point is deleted from the group. At this time, the ink drop spacing basically eliminates the interference of nozzle missing and scattered ink droplets, and obtains a deep filter ink drop image; Step 2.4, single missing points are checked in the deep filter ink drop image by using the algorithm for finding single missing points, and single missing points are checked in the deep filter ink drop image by using the algorithm for finding continuous missing points; until the image corresponding point coordinates of all nozzles in this row are found and the serial numbers are marked.

6. The optimization method for quickly checking the inkjet status of a nozzle through a camera according to claim 5, characterized in that: In step 2.2, the segmentation algorithm includes the following steps: Step 2.2.1, the pixel value of the sample point in the Y direction in the image is marked as Y i , where i represents the number of all samples, for Y i The same values ​​are combined and recorded as Y n , where n represents the number of Y samples after merging, the number of records; Step 2.2.2, after merging Y n Dynamically partition clusters, when Y n -Y n-1 = 1, the two coordinates are considered adjacent and classified into the same cluster. n -Y n-1 >1, the two coordinates are considered to be non-adjacent and classified into different clusters. Each cluster is denoted by C m , M represents the number of clusters, and the mean A of all points in the cluster is calculated m and the number N m ; Step 2.2.3, select the three clusters with the largest number of points; Step 2.2.4: Take the mean of the centers of adjacent clusters to calculate the dividing line value S between clusters m =(A m +A m+1 ) / 2; Step 2.2.5: The original sample is divided into two groups according to the segmentation line value S. m to split.

7. The optimization method for quickly checking the inkjet status of a nozzle through a camera according to claim 6, characterized in that: The algorithm for finding a single missing point includes the following steps: Calculate the distance D between two adjacent points in the X direction of each group of points i , and the spacing D i Sort and generate D i ', for D i 'Take the median value D i '(I / 2), get the median value of the spacing as the actual ink drop spacing D = D i '(I / 2), I is the number of all samples; Draw a circle with a set radius as the center by adding a standard spacing D to the right of the current point. Search for ink dots from all the points in each group above in the area inside the circle. If they exist, they are determined to be normal ink dots. Search for ink dots to the right based on the currently found ink dots.

8. The optimization method for quickly checking the inkjet status of a nozzle through a camera according to claim 7, characterized in that: The algorithm for finding consecutive missing ink dots includes the following steps: when it is detected that several adjacent ink droplets are all missing dots, the hole positions are corrected again with reference to the results of the adjacent front and back rows; and by analogy, the image corresponding point coordinates of all nozzles in this row are found and the serial numbers are marked.

9. The optimization method for quickly checking the inkjet status of a nozzle through a camera according to claim 1, characterized in that: Abnormal interference includes ink droplet scatter, ink droplet scratch, or ink droplet adhesion; The nucleus is smaller than a normal ink droplet and larger than the median value of the ink droplet scatter points; Normal ink droplets cannot be removed during the preliminary removal of interfering ink dots.

10. An optimized system for quickly checking the inkjet status of a nozzle through a camera, characterized in that: The method is implemented by using an optimization method for quickly checking the inkjet state of a nozzle through a camera as described in any one of claims 1 to 9, comprising: A data acquisition module, the data acquisition module is used to observe and locate ink droplets of inkjet printing nozzles, select a suitable inkjet printing nozzle as a qualified nozzle, and record the parameters of ink droplets currently sprayed on the test film by the qualified nozzle; A data processing module, the data processing module is used to obtain an ink drop image on the test film, filter out interfering ink dots in the ink drop image by ink drop distribution state and morphology screening method, obtain the filtered screened ink drop image, and identify the hole position of the abnormal nozzle corresponding to the abnormal ink drop by the ink drop distribution state and morphology screening method; A data compound module is used to observe and measure ink droplets on the screened abnormal nozzles.

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