阅读说明：本技术 基于图像处理实时监控喷墨打印头角度的方法及系统 (Method and system for monitoring angle of ink-jet printing head in real time based on image processing ) 是由 叶芸 刘兰 秦新智 郭太良 陈恩果 于 2021-08-02 设计创作，主要内容包括：本发明涉及一种基于图像处理实时监控喷墨打印头角度的方法及系统,包括以下步骤：步骤S1:获取喷墨头图像；步骤S2:确定定位标识图像；步骤S3:根据定位标识图像判断对应的标识位置,并通过计算机程序计算出喷头位置在预设范围内的偏转角；同时获取喷墨头水平度以及喷墨基板水平度,确定喷墨头水平度和喷墨基板水平度的水平度夹角；步骤S4:根据喷墨头水平度和喷墨基板水平度的水平度夹角,进行判断,当水平度夹角大于预设角度值,生成水平度报警信息,根据所获得的图像信息对喷墨头进行实时监控,提示所述喷墨头所在平面的水平度需调整；步骤S5:判断喷头检测是否完成并根据角度偏移量对喷头进行调整。本发明能够解决喷墨打印由于喷头偏移造成的打印不均匀和不完整的问题,实现薄膜大面积均匀性和完整性打印。(The invention relates to a method and a system for monitoring the angle of an ink-jet printing head in real time based on image processing, which comprises the following steps: step S1, acquiring an ink jet head image; step S2, determining a positioning identification image; step S3, judging the corresponding mark position according to the positioning mark image, and calculating the deflection angle of the spray head position in the preset range by the computer program; simultaneously acquiring the levelness of the ink-jet head and the levelness of the ink-jet substrate, and determining a levelness included angle between the levelness of the ink-jet head and the levelness of the ink-jet substrate; step S4, judging according to the levelness included angle of the ink-jet head and the levelness of the ink-jet substrate, generating levelness alarm information when the levelness included angle is larger than a preset angle value, monitoring the ink-jet head in real time according to the obtained image information, and prompting that the levelness of the plane where the ink-jet head is located needs to be adjusted; and step S5, judging whether the nozzle detection is finished and adjusting the nozzle according to the angle offset. The invention can solve the problems of uneven and incomplete printing caused by the offset of the spray head in ink-jet printing, and realize the large-area uniform and complete printing of the film.)

1. A method for real-time monitoring of inkjet printhead angle based on image processing, comprising the steps of:

step S1, the ink jet head to be tested drops ink droplets on the substrate and obtains the image of the ink jet head;

step S2, determining the positioning identification image according to the obtained ink jet head image;

step S3, judging the corresponding mark position according to the positioning mark image, and calculating the deflection angle of the spray head position in the preset range by the computer program; simultaneously acquiring the levelness of the ink-jet head and the levelness of the ink-jet substrate, and determining a levelness included angle between the levelness of the ink-jet head and the levelness of the ink-jet substrate;

step S4, judging a levelness included angle according to the levelness of the ink-jet head and the levelness of the ink-jet substrate, generating levelness alarm information when the levelness included angle is larger than a preset angle value, monitoring the ink-jet head in real time according to the obtained image information, and prompting that the levelness of the plane where the ink-jet head is located needs to be adjusted;

step S5, judging whether the nozzle monitoring is completed, if not, continuing to select the undetected ink jet head; if so, determining the angle offset of the spray head, and adjusting the spray head according to the angle offset.

2. The method for real-time monitoring of inkjet printhead angle based on image processing according to claim 1, wherein the step S1 is specifically as follows: and generating a plurality of image acquisition positions corresponding to the ink jet head to be detected, and acquiring images corresponding to the image acquisition positions to obtain a plurality of ink jet head images.

3. The method for real-time monitoring of inkjet printhead angle based on image processing of claim 1, wherein the identification location corresponding to the positioning identification image is an image capture location of the positioning identification image; the identification positions are provided with a plurality of identification positions, and each identification position is provided with a corresponding reference identification position.

4. The method for real-time monitoring of inkjet printhead angle based on image processing of claim 3, wherein the generating of levelness alarm information is specifically: and respectively calculating the distances between the plurality of identification positions and the corresponding reference identification positions to obtain a plurality of identification offsets, and generating levelness alarm information when any one of the identification offsets is larger than a preset offset range value.

5. The method for real-time monitoring of inkjet print head angle based on image processing as claimed in claim 1, wherein the determining of the angular offset of the nozzle and the adjusting of the nozzle according to the angular offset are specifically: determining the geometric center of the mark image, obtaining the offset between the mark image and the geometric center of the corresponding ink jet head pattern, obtaining the average value of the offset of the multiple nozzles, and calculating the deflection angle through Matlab.

6. A system for monitoring the angle of an ink-jet printing head in real time based on image processing is characterized by comprising a printing module, a control module, an ink droplet input module, a substrate receiving module, an image acquisition module, a determination module, a position acquisition module, a position generation module, a levelness acquisition module, an included angle calculation module and a levelness alarm module; the printing comprises the steps of respectively connecting an ink drop input module and a substrate receiving module; the control module is respectively connected with the image acquisition module, the determination module, the position acquisition module, the position generation module, the levelness acquisition module, the included angle calculation module and the levelness alarm module; the printing module is connected with the control module.

Technical Field

The invention relates to the technical field of ink-jet printing, in particular to a method and a system for monitoring an angle of an ink-jet printing head in real time based on image processing.

Background

Due to the advantages of direct imaging, low cost, high efficiency, high yield, flexibility and the like, the ink-jet printing technology has wide application scenes such as photoelectric device preparation, flexible wearable printing electronics and the like. More specifically, when the 0LED device is manufactured, ink is injected into the pixel pits of the glass substrate by an ink jet head of an ink jet printing device in an ink jet printing manner, so as to form a material film on the 0LED device. Related methods for controlling inkjet printing have been proposed: 1. the direction of ink-jet printing is determined according to the ratio of the ink-jet printing speed to the ejection frequency of the ink material, so that the phenomenon that the thickness of the material is not uniform due to ink loss caused by the fact that the system can only print in a single direction is avoided. In fact, this printing control method only ensures that the ink falls in the pixel pits in the aspect of equipment process printing mode control, does not consider the nozzle form and position errors, and cannot ensure the uniformity and the integrity of the ink. 2. The exit angle of the ink drop is quantitatively corrected according to the temperature difference formed by the front end position and the rear end position of the nozzle along the printing direction, and the accuracy of ink-jet printing is improved by adjusting the temperature. This control method requires a temperature control element to be provided for each nozzle, which is inefficient and costly when the number of nozzles is too large, and the instability of this method is accelerated once the printing environment changes due to the uncontrollable nature of the temperature. 3. And detecting the spray head to determine the offset compensation amount of the spray head, and adjusting the position of the ink jet printing head by a method of seamless splicing of the ink jet printing head. The method can not completely solve the problem of distortion of the printed image at the joint of the spray head and the spray head, and the quality of the printed image is poor. Since the nozzles are often formed with some errors in position during the manufacturing process, the position of the nozzle head may be shifted or blocked during long-term inkjet printing, and therefore, the generated ink drops often have a certain exit angle or volume error. When the position of the ink-jet head is deviated, a part of ink ejected by the ink-jet head drops outside the pixel pits, and the ink material in each pixel pit on the glass substrate is uneven, so that the film thickness uniformity and the integrity of the material film are influenced, and the quality problem of the OLED device is influenced.

Disclosure of Invention

In view of the above, the present invention provides a method and a system for monitoring an angle of an inkjet printhead in real time based on image processing, which can solve the problem of uneven and incomplete printing caused by offset of a nozzle in inkjet printing.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for real-time monitoring of inkjet printhead angle based on image processing, comprising the steps of:

step S1, the ink jet head to be tested drops ink droplets on the substrate and obtains the image of the ink jet head;

step S2, determining the positioning identification image according to the obtained ink jet head image;

step S3, judging the corresponding mark position according to the positioning mark image, and calculating the deflection angle of the spray head position in the preset range by using a computer program; simultaneously acquiring the levelness of the ink-jet head and the levelness of the ink-jet substrate, and determining a levelness included angle between the levelness of the ink-jet head and the levelness of the ink-jet substrate;

step S4, judging a levelness included angle according to the levelness of the ink-jet head and the levelness of the ink-jet substrate, generating levelness alarm information when the levelness included angle is larger than a preset angle value, monitoring the ink-jet head in real time according to the obtained image information, and prompting that the levelness of the plane where the ink-jet head is located needs to be adjusted;

step S5, judging whether the nozzle monitoring is completed, if not, continuing to select the undetected ink jet head; if so, determining the angle offset of the spray head, and adjusting the spray head according to the angle offset.

Further, the step S1 is specifically: and generating a plurality of image acquisition positions corresponding to the ink jet head to be detected, and acquiring images corresponding to the image acquisition positions to obtain a plurality of ink jet head images.

Further, the identification position corresponding to the positioning identification image is the image acquisition position of the positioning identification image; the identification positions are provided with a plurality of identification positions, and each identification position is provided with a corresponding reference identification position.

Further, the generating of the levelness alarm information specifically includes: and respectively calculating the distances between the plurality of identification positions and the corresponding reference identification positions to obtain a plurality of identification offsets, and generating levelness alarm information when any one of the identification offsets is larger than a preset offset range value.

Further, determining the angular offset of the nozzle, and adjusting the nozzle according to the angular offset specifically includes: determining the geometric center of the mark image, obtaining the offset between the mark image and the geometric center of the corresponding ink jet head pattern, obtaining the average value of the offset of the multiple nozzles, and calculating the deflection angle through Matlab.

A system for monitoring the angle of an ink-jet printing head in real time based on image processing comprises a printing module, a control module, an ink droplet input module, a substrate receiving module, an image acquisition module, a determination module, a position acquisition module, a position generation module, a levelness acquisition module, an included angle calculation module and a levelness alarm module; the printing comprises the steps of respectively connecting an ink drop input module and a substrate receiving module; the control module is respectively connected with the image acquisition module, the determination module, the position acquisition module, the position generation module, the levelness acquisition module, the included angle calculation module and the levelness alarm module; the printing module is connected with the control module.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, on the premise of not changing the ink-jet printing equipment, the position of the spray head is monitored in real time through the computer auxiliary equipment, the mark position is judged by using the ink-jet printing head image fed back, and the alarm information is generated according to the mark position, so that the position of the ink-jet printing head is adjusted, the printing technology is more suitable for industrialization, the large-area, high-performance and low-cost printing process is more favorably realized, and the yield of ink-jet printing is improved.

Drawings

FIG. 1 is a schematic diagram of the operation of an ink jet print head according to one embodiment of the present invention;

FIG. 2 is a schematic view of a calibration nozzle in accordance with an embodiment of the present invention;

FIG. 3 is a flow chart of a method in an embodiment of the present invention;

FIG. 4 is a schematic diagram of a system according to an embodiment of the invention;

FIG. 5 is a schematic diagram of a controller according to an embodiment of the present invention;

FIG. 6 is a schematic view of a localization marker in accordance with an embodiment of the present invention;

FIG. 7 is a sequence diagram of ink drops ejected simultaneously by multiple nozzles in one embodiment of the invention;

FIG. 8 is a schematic view of the ink drop firing angle in one embodiment of the present invention.

Detailed Description

The invention is further explained below with reference to the drawings and the embodiments.

In this embodiment, referring to fig. 1, an operating principle of inkjet printing for manufacturing an OLED device is that an inkjet head injects ink droplets to a substrate, and the substrate moves in a two-dimensional space, and a digital pulse driver controls nozzles. However, in long-term inkjet printing, there may be various factors that cause the actual positions of the nozzles to shift or to form blockages. The user can correct the nozzles prior to ink jet printing. During the calibration process, the user is required to manually calibrate the position of the nozzle. However, when the number of nozzles is too large, this method is not practical at all, which not only wastes a lot of manpower and is inefficient, but also may cause a certain error between the nozzle calibration position and the actual position due to improper operation or operation deviation of the user. Referring to fig. 2, which is a prior art calibration nozzle, it can be seen that, by capturing an image of a row of nozzles, the image is displayed on a calibration interface of a display screen of an inkjet control terminal, where the calibration interface may have a cross cursor 202 for identifying the nozzles, a user moves the cross cursor 202 to the center of a first nozzle 204, the inkjet control terminal records the current coordinates of the cross cursor as the coordinates of the nozzles 204 to calibrate the position for the first nozzle 204, and then the user can move the cross cursor to the center of a last nozzle 206, and the inkjet control terminal records the current coordinates of the cross cursor as the coordinates of the nozzle 206 in fig. 2 to calibrate the position for the last nozzle 206. Since the spacing distance between the nozzles is fixed, the positions of all nozzles can be determined based on the positions to which the nozzles 204 and 206 are calibrated.

Important specifications of the inkjet printhead include positioning accuracy of droplets, inkjet droplet volume, printing reliability and yield, and the like. The target location for drop fall is determined by the geometry of the display screen, and drop volume is determined primarily by the print head diameter. Since the pixel size of the display screen is typically in the order of microns, higher resolution requires smaller volumes of droplets and more precise positioning. For example, when 1-2 million droplets with a diameter of about 25 μm are deposited on a color display substrate with a pixel resolution of 100-150 ppi (sub-pixel size of about 85-55 μm) and a size of 35.56cm, a printing error of the whole pixel substrate may be caused by a slight deviation of droplet positioning, so that a device with accurate printing positioning and high resolution can be obtained by requiring a printing head size of about 10pl and droplet falling accuracy within ± 10 μm. Drop placement errors are mainly caused by mechanical deflection of the print deck and the deflection angle of the drops at the printhead exit. The equipment used for manufacturing the ink-jet printing display screen is generally provided with a professional high-precision printing platform (such as an air bearing platform), and the requirement of mechanical displacement precision can be met.

The deflection angle of the droplets at the printhead exit is influenced by the design of the printhead and the ink formulation, since the printheads used to produce the display are specially designed and manufactured to have less and less influence on the droplet deflection, which typically does not exceed 10 mrad. Through the design of the printing head and the optimization of ink, the deviation angle of liquid drops can reach +/-2 mrad, and the corresponding printing resolution can reach 200 ppi. In addition, the size of the ejected ink drop can be reduced or the spreading and wetting behavior of the ink drop on the surface of the substrate can be controlled by optimizing the chemical composition of the ink, regulating the chemical composition or the physical structure of the surface of the substrate and the like, and the resolution of ink-jet printing can also be effectively improved. These methods of improving print resolution are all very important in the fabrication of OLED displays. Each print head has its corresponding ink ejection position, a marker image is determined based on the ink jet head, and the position of the ink jet head is adjusted based on the marker image.

Therefore, referring to fig. 3, the present embodiment provides a method for real-time monitoring an angle of an inkjet printhead based on image processing, comprising the following steps:

step S1, the ink jet head to be tested drops ink drops on the substrate to obtain an ink jet head image;

step S2, determining the positioning identification image according to the obtained ink jet head image, which comprises the following steps: extracting the image characteristics of the ink gun image, and taking the ink gun image as a positioning identification image when the image characteristics of the ink gun image are matched with the set identification characteristics;

step S3, judging the corresponding mark position according to the positioning mark image, and calculating the deflection angle of the spray head position in the preset range; simultaneously acquiring the levelness of the ink-jet head and the levelness of the ink-jet substrate, and determining a levelness included angle between the levelness of the ink-jet head and the levelness of the ink-jet substrate;

step S4, judging according to the levelness included angle of the ink-jet head and the levelness of the ink-jet substrate, generating levelness alarm information when the levelness included angle is larger than a preset angle value, monitoring the ink-jet head in real time according to the obtained image information, and prompting that the levelness of the plane where the ink-jet head is located needs to be adjusted;

step S5, judging whether the nozzle monitoring is completed, if not, continuing to select the undetected ink jet head; if so, determining the angle offset of the spray head, and adjusting the spray head according to the angle offset.

In this embodiment, preferably, step S1 specifically includes: and generating a plurality of image acquisition positions corresponding to the ink jet head to be detected, and acquiring images corresponding to the image acquisition positions to obtain a plurality of ink jet head images.

In this embodiment, preferably, the identification position corresponding to the positioning identification image is an image acquisition position of the positioning identification image; the identification positions are provided with a plurality of identification positions, and each identification position is provided with a corresponding reference identification position.

In this embodiment, preferably, the generating of the levelness alarm information specifically includes: and respectively calculating the distances between the plurality of identification positions and the corresponding reference identification positions to obtain a plurality of identification offsets, and generating levelness alarm information when any one of the identification offsets is larger than a preset offset range value.

In this embodiment, preferably, the determining an angular offset of the nozzle and adjusting the nozzle according to the angular offset specifically include: determining the geometric center of the mark image, obtaining the offset between the mark image and the geometric center of the corresponding ink jet head pattern, obtaining the average value of the offset of the multiple nozzles, and calculating the deflection angle through Matlab, wherein the calculation is specifically carried out according to a formula:and (6) performing calculation.

The arctan function is represented in Matlab with codes as follows:

figure(1)

x=-pi/2:0.01:pi/2;

y=tan(x);

plot(y,x);

set(gca,'YTick',[-pi:pi/2:pi])

set(gca,'ytickLabel',{'-π','-π/2','0','-π/2','π'})

grid on

axis([-1.2 2*pi -1.2 2*pi])。

in this embodiment, a method and a system for monitoring an angle of an inkjet printing head in real time based on image processing are also provided, including a printing module, a control module, an ink droplet input module, a substrate receiving module, an image acquisition module, a determination module, a position acquisition module, a position generation module, a levelness acquisition module, an included angle calculation module, and a levelness alarm module; the printing comprises the steps of respectively connecting an ink drop input module and a substrate receiving module; the control module is respectively connected with the image acquisition module, the determination module, the position acquisition module, the position generation module, the levelness acquisition module, the included angle calculation module and the levelness alarm module; the printing module is connected with the control module.

Preferably, the image acquiring module is configured to acquire a plurality of inkjet head images for the inkjet head; a determination module for determining a positioning identification image among the plurality of inkjet head images; the position acquisition module is used for acquiring the identification position corresponding to the positioning identification image; and the position alarm module is used for generating alarm information according to the identification position, and the alarm information is used for prompting that the position of the ink gun needs to be adjusted.

In the present embodiment, preferably, referring to fig. 5, fig. 5 schematically shows a hardware structure 503 of the controller. Taking a processor 501 as an example, the processor 501 and the memory 502 may be connected by a bus or other means, and fig. 5 illustrates the connection by the bus as an example. The memory 502, which is a non-volatile computer-readable storage medium, may be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as program instructions/modules corresponding to the printing method in the embodiments of the present invention. The processor 501 executes various functional applications of the server and data processing, i.e., a printing method of the above-described method embodiment, by executing the nonvolatile software program, instructions, and modules stored in the memory 502. Preferably, the memory 502 may include a storage program area that may store an operating system, an application program required for at least one function, and a storage data area that may store data created according to use of a printing apparatus of an inkjet printer, and the like. Further, the memory 502 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some embodiments, memory 502 optionally includes memory located remotely from processor 501, which may be connected to the printing device of an inkjet printer via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

Referring to fig. 5, the one or more modules are stored in the memory 502 and when executed by the at least one processor 501 perform the printing method in any of the method embodiments described above, e.g., the method steps of fig. 3 described above.

In this embodiment, referring to fig. 6, when the carrying fixture 606 moves along the X axis and the image capturing device 604 moves along the Y axis, and when reaching a certain image capturing position (X, Y), the image capturing device 604 may capture an image of the positioning mark of the ink filling member 608 or the positioning mark of the carrying fixture 606, and the obtained inkjet head image includes the positioning mark, that is, the inkjet head image is a positioning mark image. In specific implementation, the image acquisition position corresponding to the positioning identification image may be used as an identification position corresponding to the identification image, that is, the current position of the positioning identification. For example, at the arrival of a certain image acquisition position (x, y).

Referring to fig. 8, when the ink drop has a current deflection angle, the computer device generates a corresponding alarm message, calculates a required compensation amount according to the deflection angle, and then performs a corresponding adjustment according to the compensation amount. The printing method in the above-described embodiment is performed, for example, the steps in fig. 3 are performed.

According to the embodiment, when the position of the spray head generates the offset within a certain range, the horizontal included angle between the spray head and the substrate is detected, and when the horizontal included angle is larger than the preset angle, the system can give out prompt information, so that the phenomenon that ink drops drop out of a preset position due to the position offset is avoided, and the quality of an LED device is improved.

The product can execute the method provided by the embodiment of the invention, and has corresponding functional modules and beneficial effects of the execution method. For technical details that are not described in detail in this embodiment, reference may be made to the method provided by the embodiment of the present invention. The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a general hardware platform, and certainly can also be implemented by hardware. It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware related to instructions of a computer program, which can be stored in a computer readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a read-only memory or a random access memory. It should be finally noted that the above embodiments are only intended to illustrate the technical solutions of the present invention, and not to limit the same, and that under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of brevity, although the present invention is described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions described in the foregoing embodiments can be modified or part of the technical features can be equivalently replaced, and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.