A method for measuring the volume of a large number of droplet arrays and its application

Abstract

The present invention belongs to the field of novel displays, specifically relating to a method for measuring the volume of a massive droplet array and its application. The method comprises: performing array mapping of a massive droplet deposition area on a planar substrate, stitching the captured image array to obtain an image of the complete deposition observation area; performing image processing on the image of the deposition observation area to separate the deposition areas of each droplet; extracting the morphological characteristics of each droplet deposition area based on its deposition area; and predicting the deposition volume of each droplet within the deposition observation area on the planar substrate using a pre-established mapping relationship between the morphological characteristics of the droplet deposition area and the droplet volume based on the morphological characteristics of each droplet deposition area. Using only a common industrial camera, the present invention achieves low-cost, efficient, and high-precision volume measurement and uniformity assessment of massive droplet arrays, providing a reference for selecting printing parameters.

Description

Technical Field

[0001] The present invention belongs to the field of novel displays, and more specifically, relates to a method for measuring the volume of a massive droplet array and its application. Background Art

[0002] Inkjet printing is a non-contact, micron-scale printing process that directly sprays nanoscale solutions onto flexible or rigid substrates. Compared to traditional film-forming techniques, it does not require a vacuum environment and offers advantages such as low energy consumption, low cost, high material utilization, and flexible deposition materials. It is currently one of the most frequently discussed emerging thin film deposition technologies.

[0003] Currently, inkjet printing utilizes two film-forming methods: electrofluidic dot-spraying and electrofluidic atomization. With both methods, printing quality is significantly affected by printing parameters, and the spray flow rate is difficult to regulate, making it difficult to precisely control the thickness of the resulting inkjet-printed film. Consequently, the industrialization of inkjet printing technology is challenging in producing films with stable quality and uniform, controllable thickness. Film quality depends largely on the uniformity of the inkjet droplet volume distribution and volumetric uniformity. Therefore, in industrial production, identifying the printing parameter range that achieves uniform droplet volume distribution is crucial before film production.

[0004] The current methods for measuring the volume of inkjet printing droplets include: using a CCD camera or a high-speed camera for observation. This method has a slow efficiency in observing the volume of electrofluid dot spraying and is difficult to adapt to the production cycle. When used to observe electrofluid atomization, it can only observe the contour of the fog cone; using a particle image velocimeter to measure particles in the flow field. This method tends to measure the number of particles and the flow rate, and has a large error in measuring the particle volume; using a phase Doppler particle analyzer, but when measuring the fog cone, it can only measure the droplet volume at a certain point in the fog cone, not the entire fog cone, and is costly; using a CCD camera to observe the deposition distribution of particles on the substrate. This method only stays at the stage of calculating the number of particles and does not study volume measurement. Compared with electrofluidic dot-jet printing, electrofluidic atomization printing droplets have the characteristics of huge quantity, small size and large deposition range. Often a nozzle can spray out tens of thousands of droplets per second, with a droplet volume of 1 to 100 pL and a deposition range of more than 8 mm. However, all current droplet measurement methods cannot achieve efficient and high-precision droplet volume measurement of huge droplets, and it is also difficult to achieve efficient and high-precision droplet volume distribution uniformity evaluation.

[0005] In summary, proposing an efficient and high-precision method for measuring the volume of massive droplet arrays suitable for inkjet printing has become one of the research focuses in this field. Summary of the Invention

[0006] In response to the defects of the existing technology and the need for improvement, the present invention provides a method for measuring the volume of a large number of droplets and its application, the purpose of which is to perform efficient and high-precision volume measurement of a large number of tiny droplets generated during the inkjet printing process.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for measuring the volume of a large droplet array is provided, comprising:

[0008] Perform array image acquisition on the massive droplet deposition area on the flat substrate, and perform image stitching on the acquired image array to obtain an image of the complete deposition observation area;

[0009] Performing image processing on the image of the deposition observation area to separate the deposition area of ​​each droplet; extracting the morphological characteristics of the droplet deposition area based on the deposition area of ​​each droplet;

[0010] Based on the morphological characteristics of each droplet deposition area, a pre-established mapping relationship between the morphological characteristics of the droplet deposition area and the droplet volume is used to predict the deposition volume of each droplet on the plane substrate within the deposition observation area;

[0011] In which, the mapping relationship is obtained by training through machine learning, and the training sample set used is obtained by extracting information from droplets obtained in the following manner: using a printing solution that is the same as the printing solution used to prepare the giant droplet array, and inkjet printing on a planar substrate of the same type as the planar substrate.

[0012] Furthermore, there is no fusion between the droplets in the deposition observation area; and when taking images, array images are taken at an angle perpendicular to the deposition observation area, and there are overlapping areas between adjacent images.

[0013] Furthermore, the image processing method is as follows: performing binarization processing on the image of the deposition observation area; performing morphological processing on the binarized image to separate the deposition area of ​​a single droplet;

[0014] When the massive droplet array to be measured is obtained by electrofluidic atomization, the morphological characteristics of each droplet deposition area include the inscribed circle radius, circumscribed circle radius, deposition area, and radial relative position of the deposited droplet;

[0015] When the massive droplet array to be measured is obtained by electrofluidic point spraying, the morphological characteristics of the deposition area of ​​each droplet include the inscribed circle radius, the circumscribed circle radius and the deposition area of ​​the deposited droplet.

[0016] Furthermore, in the training of the mapping relationship, back propagation is performed to update the parameters by taking the root mean square error RMSE(X,f) between the predicted value and the true value label as the minimum;

[0017]

[0018] Y=(V1,V2,…,V i ) T ;

[0019]

[0020] Where X is the data set consisting of the deposition area morphology feature value vectors of all droplets in the deposition observation area, x i is the morphological characteristic value vector of the deposition area of ​​the i-th droplet, Y is the true value vector consisting of the volume true values ​​of all droplets in the deposition observation area, V i is the true value of the volume of the i-th droplet, i is an integer from 1 to n, n is the number of droplets in the deposition observation area, f(x i ) is based on x i The predicted volume value, m represents the total number of training samples.

[0021] The present invention also provides a method for evaluating the volume of a large droplet array, comprising:

[0022] Dividing a binary image of size M×N obtained when performing the method for measuring the volume of a large number of droplets into a plurality of regions of size m×n, where m and n are divisible by M and N respectively;

[0023] Calculating the total deposition volume of the droplets in each region on the planar substrate based on the deposition volume of each droplet in the region obtained by the method for measuring the volume of the massive droplet array;

[0024] The uniformity of the deposition volume distribution in the deposition observation area is measured by the difference between the total deposition volumes of the droplets in each area, and / or the volume uniformity of the giant droplet array in the deposition observation area is calculated.

[0025] Furthermore, the difference in the total droplet deposition volume in each region is calculated by the coefficient of variation CV of the total droplet deposition volume corresponding to each region. D Quantization, the calculation method is as follows:

[0026]

[0027]

[0028]

[0029]

[0030] Among them, num is the number of divided areas; CV Dis the coefficient of variation, the smaller the value, the more uniform the sediment volume distribution; σ S is the standard deviation of the total droplet deposition volume corresponding to num regions; is the average value of the total droplet deposition volume corresponding to num regions; S j is the total deposition volume of droplets in the jth block area; j is an integer from 1 to num.

[0031] Furthermore, the total droplet deposition volume S in the jth block area j The calculation method is:

[0032]

[0033]

[0034] Among them, ndrop j is the total number of droplets in the jth block area; V ji is the true value of the volume of the i-th droplet in the j-th block area; is the predicted volume of the i-th droplet in the j-th block area; x ji is the morphological feature value vector of the deposition area of ​​the i-th droplet in the j-th block area, including all the morphological feature information of the deposition area of ​​the droplet; I ji is the deposition area of ​​the i-th droplet in region j, i ranges from 1 to ndrop j ;Area ji represents the deposition area of ​​the i-th droplet in the j-th block area.

[0035] Furthermore, the volume uniformity is calculated as follows:

[0036] U D =(D Vmax -D Vmin ) / D V50 ;

[0037]

[0038] Where U D V is a measure of the volume uniformity of the droplets; Vmin 、V V50 、V Vmax They are: accumulate the droplet deposition volume in order from small to large, and when the cumulative value is equal to min%, 50%, and max% of the total droplet deposition volume, the corresponding droplet deposition volume is calculated according to the sampling principle of max+min=100. The specific values ​​of max and min are determined according to actual production needs; D Vmin 、D V50 、D Vmax The volume is V Vmin 、VV50 、V Vmax The corresponding droplet diameter in flight.

[0039] The present invention also provides a device for measuring and evaluating the volume of a large droplet array, which is used to perform a large droplet array volume measurement method and a large droplet array volume evaluation method as described above, comprising: a visual unit, a control unit, and a processing unit;

[0040] The visual unit performs image acquisition operations under the control of the control unit, and the processing unit is used to perform image stitching, feature extraction, and calculation of liquid deposition volume, uniformity of deposition volume distribution in the deposition observation area, and volume uniformity of a large number of droplet arrays in the deposition observation area.

[0041] The present invention also provides a method for determining printing parameters for inkjet printing, comprising:

[0042] (1) performing pre-printing on a planar substrate using preset printing parameters, measuring the volume of a large droplet array using a method for measuring the volume of a large droplet array as described above, and obtaining deposition volume distribution uniformity and volume uniformity using a method for evaluating the volume of a large droplet array as described above;

[0043] (2) Determine whether both the deposition volume distribution uniformity and the volume uniformity meet the standards. If so, use the preset printing parameters as the printing parameters for formal printing. Otherwise, reset the printing parameters and repeat step (1) until the printing parameters for formal printing are determined. When the number of iterations reaches a threshold and no printing parameters that meet both the deposition volume distribution uniformity and the volume uniformity are found, it is determined that the fault does not come from the printing parameter setting and the iteration is stopped.

[0044] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0045] (1) The present invention proposes a method for measuring the volume of a large number of droplet arrays. The method captures droplet images, obtains droplet deposition characteristics, and directly predicts the droplet volume from the deposition image by mapping the droplet deposition characteristics to the droplet volume. The method has a measurement efficiency far higher than using a white light interferometer to measure the volume of each droplet, and also higher than using a camera to measure each droplet separately, thus achieving high-efficiency measurement of the droplet array. Specifically, when capturing the deposited droplet images, a high-magnification CCD camera can be used to capture multiple images for stitching, resulting in high-precision images. Through image processing and analysis, high-precision measurement of the droplet array can be achieved.

[0046] (2) The method for measuring the volume of a large number of droplet arrays proposed in the present invention requires only an ordinary industrial camera, lens and light source as the observation system. Compared with measurement systems using high-speed cameras, white light interferometers, particle image velocimeters and the like, the present invention has low cost, small size, requires low motion precision, and is easy to use in actual production.

[0047] (3) The present invention further utilizes the above-mentioned method for measuring the volume of a giant droplet array. After obtaining the volume of the giant droplet, the uniformity of the deposition volume distribution in the deposition observation area and / or the volume uniformity of the giant droplet array in the deposition observation area are analyzed to achieve efficient and high-precision evaluation of the film quality, which makes an important contribution to the rapid and efficient determination of the printing parameter range.

[0048] (4) The present invention uses preset printing parameters to perform pre-printing on a flat substrate, uses the above-mentioned method for measuring the volume of a large droplet array to measure the volume of the large droplet array, and uses the above-mentioned method for evaluating the volume of a large droplet array to obtain the uniformity of the deposition volume distribution and the uniformity of the volume. Based on whether the uniformity of the deposition volume distribution and the uniformity of the volume meet the standards, the printing parameters for the formal printing are determined efficiently and accurately. Furthermore, the movement speed of the nozzle for the formal printing can be calculated based on the nozzle flow rate and film thickness requirements in the pre-printing stage, and ultimately, a thin film with stable quality and uniform and controllable film thickness can be efficiently achieved. The method of the present invention has application value in the actual manufacturing of new display devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A flowchart of a method for measuring the volume of a large number of droplets array provided in an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a pre-printing process provided by an embodiment of the present invention;

[0051] Figure 3 An image processing flow chart provided by an embodiment of the present invention;

[0052] Figure 4 A schematic diagram of morphological feature extraction provided by an embodiment of the present invention;

[0053] Figure 5 A schematic diagram of a method for calculating droplet deposition distribution provided in an embodiment of the present invention;

[0054] Figure 6 A schematic diagram of a method for calculating the volume of droplets at different positions within a grid provided by an embodiment of the present invention;

[0055] Figure 7 A schematic diagram of a method for calculating droplet volume uniformity provided in an embodiment of the present invention;

[0056] Figure 8A schematic diagram of detection closed-loop feedback control for a printing system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is 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 for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0058] Example 1

[0059] A method for measuring the volume of a large number of droplet arrays, such as Figure 1 Shown, including:

[0060] Perform array image acquisition on the massive droplet deposition area on the flat substrate, and perform image stitching on the acquired image array to obtain an image of the complete deposition observation area;

[0061] Performing image processing on the image of the deposition observation area to separate the deposition area of ​​each droplet; extracting the morphological characteristics of the droplet deposition area based on the deposition area of ​​each droplet;

[0062] Based on the morphological characteristics of each droplet deposition area, a pre-established mapping relationship between the morphological characteristics of the droplet deposition area and the droplet volume is used to predict the deposition volume of each droplet on the plane substrate within the deposition observation area;

[0063] In which, the mapping relationship is obtained by training through machine learning, and the training sample set used is obtained by extracting information from droplets obtained in the following manner: using a printing solution that is the same as the printing solution used to prepare the giant droplet array, and inkjet printing on a planar substrate of the same type as the planar substrate.

[0064] The method of this embodiment achieves high-precision measurement of droplet volume by photographing and stitching an array of droplet deposition images; and achieves efficient measurement of droplet volume by performing feature extraction and machine learning prediction on the droplet deposition images; that is, the method of measuring the volume of a large droplet array proposed in this embodiment can use a CCD camera to photograph the droplet deposition situation, obtain the droplet deposition characteristics, and directly predict the droplet volume from the deposition image through the mapping relationship between the droplet deposition characteristics and the droplet volume. The measurement efficiency of the method of this embodiment is much higher than using a white light interferometer to measure the volume of each droplet, and is also higher than using a camera to measure each droplet separately, achieving high-efficiency measurement of the droplet array.

[0065] As a preferred embodiment, there is no fusion between the droplets in the above-mentioned deposition observation area; and when taking pictures, the downward-looking camera is turned on to take pictures in an array, and there are overlapping areas between adjacent images.

[0066] This method uses a high-magnification CCD camera to capture multiple images and stitch them together, resulting in highly accurate images. Through image processing and analysis, high-precision measurements of droplet arrays can be achieved. The observation system requires only a CCD camera, lens, and light source. Compared to measurement systems using high-speed cameras, white-light interferometers, and particle image velocimetry, this method offers low cost, compact size, and requires less precise motion, making it easy to implement in production.

[0067] It should be noted that, in an optional scenario, the large amount of droplets deposited on the above-mentioned planar substrate may be droplets obtained in the pre-printing stage, so as to further determine whether the pre-printing parameters are qualified by evaluating whether the droplet volume distribution is qualified. Thus, optionally, as Figure 2 As shown, the droplets can be obtained by:

[0068] The nozzle moves to one end of the pre-printed flat substrate, turns on the nozzle voltage and air pressure, and after the nozzle spray is stable, it moves at a constant speed v in the X direction for a distance D x During this process, ensure that there is a section on the substrate with a width of D in the X direction. img , the deposition area where there is no fusion between droplets is used as the deposition observation area. img Must be greater than or equal to the preset minimum column width D min , the preset value is set according to the actual printing situation. If D min If it is too small, the number of droplets is insufficient, and the corresponding representation of whether the current printing parameters are qualified is not sufficient; turn on the downward-looking camera to perform array imaging to ensure that there are overlapping areas between adjacent images and the imaging area covers the entire deposition observation area; perform image stitching on the acquired image array to obtain an image Img0 of the complete deposition observation area.

[0069] At present, there are two film-making methods for inkjet printing: electrofluidic dot jetting and electrofluidic atomization. The corresponding nozzles are dot jet nozzles and electrofluidic atomization nozzles. In particular, when the nozzle is a dot jet nozzle, in order to ensure that the droplets do not merge, the above speed v should meet the following requirements: v ≥ 2 × d max ×f,d max is the diameter of the largest circumscribed circle of the droplet deposition area, and f is the droplet spraying frequency of the point spray nozzle.

[0070] In addition, the extraction of the morphological features of each droplet deposition area in the deposition observation area is completed by image processing of the image of the deposition observation area, which can be used as a preferred embodiment. The specific extraction method is:

[0071] (1) Binarize the image of the deposition observation area; perform morphological processing on the binarized image to separate the deposition area of ​​each droplet.

[0072] Specifically, such as Figure 3 As shown, the image Img0 is preprocessed. Image preprocessing includes grayscale conversion and adaptive equalization. The preprocessed image is binarized and recorded as Img_binary. The pixel value 1 in Img_binary is the droplet deposition area, and the pixel value 0 is the substrate area. Morphological processing is then performed to separate the deposition area of ​​a single droplet, where the deposition area of ​​the i-th droplet is Region_drop i ;

[0073] (2) Based on the deposition area of ​​each droplet, the morphological features of the droplet deposition area are extracted.

[0074] At present, there are two methods of making films in inkjet printing: electrofluidic dot spraying and electrofluidic atomization. Figure 4 As shown, when the large amount of droplets to be measured is obtained by electrofluidic atomization, the morphological characteristics include the radius of the inscribed circle r of the droplet. i , circumscribed circle radius R i , deposition area i and radial relative position D i .

[0075]

[0076] Among them, pix_r i 、pix_R i 、pix_Area i Region_drop i The number of pixels occupied by the radius of the inscribed circle, the number of pixels occupied by the radius of the circumscribed circle, and the total number of pixels occupied; M is the magnification of the high-power vision system (i.e., the downward-looking camera); y i Region_drop i The center of gravity is the vertical coordinate in the image Img0; Y is the vertical coordinate of the nozzle center corresponding to Img0; i is an integer from 1 to N, and N is the total number of droplets in the deposition image.

[0077] When the large amount of droplets to be measured is obtained by electrofluidic point spraying, the morphological characteristics include the inscribed circle radius r i , circumscribed circle radius R i and deposition area i .

[0078] As a preferred implementation, in the training of the above mapping relationship, the root mean square error RMSE(X,f) between the predicted value and the true value label is used as the performance indicator of the regression task, and the mapping relationship is trained with the goal of minimizing this performance indicator;

[0079]

[0080] Among them, f(x i ) is the volume prediction value based on the morphological characteristics of the deposition area of ​​the i-th droplet, V i is the true value of the volume of the i-th droplet, and m represents the total number of training samples.

[0081] The true value of the volume of each droplet can optionally be obtained by:

[0082] Place the deposition observation area on the white light interferometer platform and use white light interferometry to measure the true value V of the volume of each droplet in the deposition observation area. i , and the volume corresponds to the morphological characteristics of the droplet deposition area to establish a data set; the data set contains the morphological characteristics of the droplet deposition area of ​​each droplet in the deposition observation area, x i is the eigenvalue vector of the i-th droplet, Y is the vector of the true value of the droplet volume, n is the number of data in the data set, and i is an integer from 1 to n:

[0083]

[0084] x i =(r i ,R i ,Area i ,D i ) T

[0085] Y=(V1,V2,…,V i ) T

[0086] Based on the machine learning algorithm, the regression relationship between the droplet volume and the morphological characteristics of the deposition area is obtained, and the droplet volume V is established. i The prediction model f(x i ); is the predicted volume of the i-th droplet.

[0087] It should be noted that since the deposition conditions of different solutions on different planar substrates vary greatly, the same prediction model cannot be applied. Therefore, without changing the type of planar substrate and the printing solution, the prediction model f(x i ), by measuring the x of each droplet i , and get the predicted value of each droplet volume

[0088] Example 2

[0089] A method for evaluating the volume of a large number of droplet arrays, such as Figure 2 Shown, including:

[0090] Dividing a binarized image of size M×N obtained when performing a method for measuring the volume of a large droplet array as described in Example 1 into a plurality of regions of size m×n;

[0091] Calculating the total deposition volume of the droplets in each region on the planar substrate based on the deposition volume of each droplet in the region obtained by the method for measuring the volume of the massive droplet array;

[0092] The uniformity of the deposition volume distribution in the deposition observation area is measured by the difference between the total deposition volumes of the droplets in each area; where m and n are divisible by M and N respectively; and / or, the volume uniformity of the giant droplet array in the deposition observation area is calculated.

[0093] As a preferred embodiment, the difference in the total deposition volume of the droplets in each region is specifically: the ratio of the standard deviation of the total deposition volume of the droplets corresponding to the multiple regions to the average value of the total deposition volume of the droplets corresponding to the multiple regions, such as Figure 5 As shown, it can be expressed as:

[0094]

[0095]

[0096]

[0097]

[0098] Among them, num is the number of divided areas; CV D It is a measure of the uniformity of the sediment volume distribution. The smaller the value, the more uniform the sediment volume distribution. S is the standard deviation of the total droplet deposition volume corresponding to the above multiple regions; is the average value of the total droplet deposition volume corresponding to the above multiple regions; S j is the total deposition volume of droplets in the jth block area; j is an integer from 1 to num.

[0099] There are two cases for the droplets in region j, such as Figure 6As shown in the figure, one type of droplet has no intersection with the grid boundary line, and its deposition volume estimate can be directly used for cumulative calculation; the other type of droplet is located on the grid boundary line, and only a part of it is located in area j. It is necessary to further estimate the deposition volume in area j based on the ratio of the area of ​​the droplet deposited in area j to the total droplet deposition area; the total droplet deposition volume S in the jth block area j The calculation method is:

[0100]

[0101]

[0102] Among them, ndrop j is the total number of droplets in the jth block area; V ji is the true value of the volume of the i-th droplet in the j-th block area; is the predicted value of the deposition volume of the i-th droplet; x ji is the eigenvalue vector of the i-th droplet in the j-th block area (including all the morphological feature information of the droplet deposition area); I ji is the area of ​​the i-th droplet in region j; i ranges from 1 to ndrop j ;Area ji represents the deposition area of ​​the i-th droplet in the j-th block area.

[0103] That is, as a preferred embodiment, when calculating the total droplet deposition volume corresponding to each region, if there is a droplet partially located in the region, the deposition volume of the droplet in the region is calculated as follows:

[0104] The predicted value of the deposition volume of the droplet is multiplied by the percentage of the deposition area of ​​the droplet in the region to the total deposition area of ​​the droplet, and the product is used as the deposition volume of the droplet in the region.

[0105] As a preferred embodiment, Figure 7 As shown, the calculation method of the above volume uniformity is:

[0106] U D =(D Vmax -D Vmin ) / D V50 ;

[0107]

[0108] Where U D V is a measure of the volume uniformity of the droplets; Vmin 、V V50 、V VmaxThey are: accumulate the droplet deposition volume in order from small to large, and when the cumulative value is equal to min%, 50%, and max% of the total droplet deposition volume, the corresponding droplet deposition volume is calculated according to the sampling principle of max+min=100. The specific values ​​of max and min are determined according to actual production needs; D Vmin 、D V50 、D Vmax The volume is V Vmin 、V V50 、V Vmax The corresponding droplet diameter in flight.

[0109] Example 3

[0110] A device for measuring and evaluating the volume of a large number of droplets array, comprising:

[0111] The visual unit includes a high-magnification downward detection module and a low-magnification downward detection module. The high-magnification downward detection module includes a camera, a matching high-magnification lens and a matching coaxial light source for collecting droplet deposition images. The low-magnification downward detection module includes a camera, a matching low-magnification lens and a matching coaxial light source for rapid positioning.

[0112] The control unit controls the camera image acquisition, light source on / off and brightness adjustment, and movement of the nozzle, substrate, and camera. The entire visual unit performs the image acquisition operation in Example 1 under the control of the control unit.

[0113] The image processing unit is used to process the images captured by the camera and complete the image stitching, feature extraction, and calculation of droplet volume, volume distribution, and volume uniformity described in the first and second embodiments.

[0114] Example 4

[0115] A method for determining printing parameters for inkjet printing, comprising:

[0116] (1) Pre-printing is performed on a flat substrate using preset printing parameters. After pre-printing and before formal printing, a downward-looking camera is turned on and the volume of the giant droplet array is measured using the method for measuring the volume of the giant droplet array described in Example 1. The volume evaluation method for the giant droplet array described in Example 2 is used to obtain the uniformity of the deposition volume distribution and the volume uniformity.

[0117] (2) Determine whether both the deposition volume distribution uniformity and the volume uniformity meet the standards. If so, use the preset printing parameters as the printing parameters for formal printing. Otherwise, reset the printing parameters and repeat step (1) until the printing parameters for formal printing are determined. When the number of iterations reaches a threshold and no printing parameters that meet both the deposition volume distribution uniformity and the volume uniformity are found, it is determined that the fault does not come from the printing parameter setting and the iteration is stopped.

[0118] That is, the methods of embodiment 1 and embodiment 2 are performed before formal printing and film forming to determine whether the printing system is working properly, such as Figure 8 As shown, the specific process can be as follows:

[0119] S1. Perform pre-printing with a set of printing parameters and calculate the deposition volume distribution uniformity CV of the droplets. D , droplet volume uniformity U D ;

[0120] S2, CV D 、U D and the preset volume distribution uniformity threshold CV D0 , preset volume uniformity threshold U D0 Compare and if all are less than the preset value, the group of printing parameters is judged to be qualified; if all are not less than the preset value, the pre-printing is judged to be unqualified;

[0121] S3. If the pre-print is qualified, calculate the nozzle movement speed v of the formal printing according to the nozzle flow and film thickness requirements in the pre-print stage. n , to start formal printing; the nozzle moving speed v n The algorithm is:

[0122]

[0123]

[0124] Among them, Q n is the nozzle flow rate calculated based on pre-printing, h is the target film thickness, S n S is the expected nozzle stroke during the formal printing process. film is the target film area; V all v is the sum of the volumes of all droplets in the pre-printed deposition observation area, which is calculated by predicting the volume of each droplet by the characteristic value of each deposited droplet in the deposition observation area and summing them up; p D is the speed of the nozzle moving during the pre-printing process; img is the width of the deposition observation area in the X direction.

[0125] S3. If the pre-print fails, it is necessary to further determine whether there are other pre-print parameter groups that can be tried. If so, pre-print again with other parameters. If not, it is determined that the fault does not come from the printing parameter settings, and further troubleshooting of the nozzle and printing environment is required.

[0126] Similarly, since there are currently two film-making methods for inkjet printing: electrofluidic dot jetting and electrofluidic atomization, for the electrofluidic dot jetting scenario, the printing parameters are: voltage amplitude, frequency and waveform; for the electrofluidic atomization deposition scenario, the printing parameters are: voltage, air pressure and printing height.

[0127] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring the volume of a large number of droplet arrays, characterized in that: include: Perform array image acquisition on the massive droplet deposition area on the flat substrate, and perform image stitching on the acquired image array to obtain an image of the complete deposition observation area; Performing image processing on the image of the deposition observation area to separate the deposition area of ​​each droplet; extracting the morphological characteristics of the droplet deposition area based on the deposition area of ​​each droplet; Based on the morphological characteristics of each droplet deposition area, a pre-established mapping relationship between the morphological characteristics of the droplet deposition area and the droplet volume is used to predict the deposition volume of each droplet on the plane substrate within the deposition observation area; The mapping relationship is obtained by training through machine learning, and the training sample set is obtained by extracting information from droplets obtained in the following manner: using a printing solution that is the same as the printing solution used to prepare the giant droplet array, and inkjet printing on a planar substrate of the same type as the planar substrate; The image processing method is as follows: performing binarization processing on the image of the deposition observation area; performing morphological processing on the binarized image to separate the deposition area of ​​a single droplet; When the massive droplet array to be measured is obtained by electrofluidic atomization, the morphological characteristics of each droplet deposition area include the inscribed circle radius, circumscribed circle radius, deposition area, and radial relative position of the deposited droplet; When the massive droplet array to be measured is obtained by electrofluidic point spraying, the morphological characteristics of the deposition area of ​​each droplet include the inscribed circle radius, the circumscribed circle radius and the deposition area of ​​the deposited droplet.

2. The method for measuring the volume of a large droplet array according to claim 1, wherein: There is no fusion between the droplets in the deposition observation area; and when taking images, array images are taken at an angle perpendicular to the deposition observation area, and there are overlapping areas between adjacent images.

3. The method for measuring the volume of a large droplet array according to claim 1, wherein: In the training of the mapping relationship, the root mean square error between the predicted value and the true value label is used Minimum is the goal, and back propagation is performed to update the parameters; Y=(V1,V2,…,V i ) T ; Where X is the data set consisting of the deposition area morphology feature value vectors of all droplets in the deposition observation area, x i is the morphological characteristic value vector of the deposition area of ​​the i-th droplet, Y is the true value vector consisting of the volume true values ​​of all droplets in the deposition observation area, V i is the true value of the volume of the i-th droplet, i is an integer from 1 to n, n is the number of droplets in the deposition observation area, f(x i ) is based on x i The predicted volume value, m represents the total number of training samples.

4. A method for evaluating the volume of a large droplet array, characterized in that: include: Dividing a binary image of size M×N obtained when performing the method for measuring the volume of a large droplet array according to any one of claims 1 to 3 into a plurality of regions of size m×n, where m and n are divisible by M and N respectively; Calculating the total deposition volume of the droplets in each region on the planar substrate based on the deposition volume of each droplet in the region obtained by the method for measuring the volume of the massive droplet array; The uniformity of the deposition volume distribution in the deposition observation area is measured by the difference between the total deposition volumes of the droplets in each area, and / or the volume uniformity of the giant droplet array in the deposition observation area is calculated.

5. The method for estimating the volume of a large droplet array according to claim 4, wherein: The difference in the total droplet deposition volume in each region is calculated by the coefficient of variation CV of the total droplet deposition volume corresponding to each region. D Quantization, the calculation method is as follows: Among them, num is the number of divided areas; CV D is the coefficient of variation, the smaller the value, the more uniform the sediment volume distribution; σ S is the standard deviation of the total droplet deposition volume corresponding to num regions; is the average value of the total droplet deposition volume corresponding to num regions; S j is the total deposition volume of droplets in the jth block area; j is an integer from 1 to num.

6. The method for estimating the volume of a large droplet array according to claim 5, wherein: The total droplet deposition volume S in the jth block area j The calculation method is: Among them, ndrop j is the total number of droplets in the jth block area; V ji is the true value of the volume of the i-th droplet in the j-th block area; is the predicted volume of the i-th droplet in the j-th block area; x ji is the morphological feature value vector of the deposition area of ​​the i-th droplet in the j-th block area, including all the morphological feature information of the deposition area of ​​the droplet; I ji is the deposition area of ​​the i-th droplet in region j, i ranges from 1 to ndrop j ;Area ji represents the deposition area of ​​the i-th droplet in the j-th block area.

7. The method for estimating the volume of a large droplet array according to claim 4, wherein: The volume uniformity is calculated as follows: U D =(D Vmax -D Vmin ) / D V50 ; Where U D V is a measure of the volume uniformity of the droplets; Vmin 、V V50 、V Vmax They are: accumulate the droplet deposition volume in order from small to large, and when the cumulative value is equal to min%, 50%, and max% of the total droplet deposition volume, the corresponding droplet deposition volume is based on the sampling principle of max+min=100. The specific values ​​of max and min are determined according to actual production needs; D Vmin 、D V50 、D Vmax The volume is V Vmin 、V V50 、V Vmax The corresponding droplet diameter in flight.

8. A device for measuring and evaluating the volume of a large number of droplet arrays, characterized in that: Used to perform a method for measuring the volume of a large droplet array as claimed in any one of claims 1 to 3 and a method for evaluating the volume of a large droplet array as claimed in any one of claims 4 to 7, comprising: a visual unit, a control unit, and a processing unit; The visual unit performs image acquisition operations under the control of the control unit, and the processing unit is used to perform image stitching, feature extraction, and calculation of liquid deposition volume, uniformity of deposition volume distribution in the deposition observation area, and volume uniformity of a large number of droplet arrays in the deposition observation area.

9. A method for determining printing parameters for inkjet printing, characterized in that: include: (1) Pre-printing is performed on a planar substrate using preset printing parameters, and the volume of the giant droplet array is measured using a method for measuring the volume of the giant droplet array as described in any one of claims 1 to 3, and the deposition volume distribution uniformity and volume uniformity are obtained using a method for evaluating the volume of the giant droplet array as described in any one of claims 4 to 7; (2) Determine whether both the deposition volume distribution uniformity and the volume uniformity meet the standards. If so, use the preset printing parameters as the printing parameters for formal printing. Otherwise, reset the printing parameters and repeat step (1) until the printing parameters for formal printing are determined. When the number of iterations reaches a threshold and no printing parameters that meet both the deposition volume distribution uniformity and the volume uniformity are found, it is determined that the fault does not come from the printing parameter setting and the iteration is stopped.

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