Real-time printing dot positioning method based on optical image

Abstract

This invention discloses a real-time positioning method for printing dots based on optical imaging. This invention relates to the field of printing positioning technology and solves the technical problem that objects may have different placement postures during printing, and the printing area cannot be identified during the printing process, leading to printing abnormalities. This invention calibrates and positions the printing dots of the printer, thereby reducing errors in subsequent printing processes. Furthermore, it analyzes the printing area during printing, combining the object's placement posture and the printer's printing direction to select appropriate printing directions and angles, adapting to the printing requirements of objects with different placement postures, reducing errors during printing, and improving printing efficiency.

Description

Technical Field

[0001] This invention relates to the field of inkjet printing positioning technology, specifically to a real-time inkjet printing point positioning method based on optical imaging. Background Technology

[0002] Existing OLED manufacturing methods typically include two types: vapor deposition and inkjet printing. Among them, inkjet printing OLED technology has a simpler manufacturing process and is more precise than vapor deposition, making it particularly advantageous when processing large-size panels.

[0003] According to Chinese Patent Application No. CN202010208317.X, a method and system for multi-error compensation positioning control of ink droplets is disclosed. The method includes the following steps: (1) performing trial printing to obtain the ink droplet flight positioning error, nozzle positioning error and substrate positioning error respectively; (2) before formal printing, performing feedforward control on the substrate movement based on the obtained ink droplet flight positioning error, nozzle positioning error and substrate positioning error; and then entering formal printing; (3) detecting and obtaining the ink droplet landing point positioning error in formal printing in real time, and performing online feedback control on the substrate movement based on the obtained ink droplet landing point positioning error.

[0004] The aforementioned patent uses an ink droplet landing observation system to conduct real-time observation and compensate for errors that cannot be observed or are not observed accurately during trial printing. For example, ink droplet positioning errors caused by airflow interference from substrate movement or other factors during ink droplet flight, and ink droplet positioning errors caused by fusion flow due to substrate movement or different order of ink droplet landing on the substrate. This reduces ink droplet positioning errors and speeds up the control response.

[0005] Some existing inkjet printers may encounter printing errors due to the different placement of the objects being transported. This mismatch in the printing area can lead to printing errors and the printer being unable to recognize the objects, resulting in printing malfunctions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a real-time positioning method for printing points based on optical imaging. This method solves the problem that objects may have different placement postures during printing, and the printing area cannot be identified during the printing process, which can lead to printing abnormalities.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a real-time positioning method for printing dots based on optical images, the method comprising the following steps:

[0008] Step 1: Conduct multiple experiments on the printing dots, and calibrate the accuracy of the printing dots based on the experimental results. The specific calibration method is as follows:

[0009] First, identify the target object, which is a regular-shaped object such as a cube, cuboid, or cylinder. Then, determine the printing area of ​​the target object and record this area as the target printing area. Simultaneously, perform printing processing based on this area to generate multiple sets of actual printing points, as shown in the attached diagram. Figure 2 As shown, the multiple sets of actual printing points obtained may coincide with the printing points corresponding to the printing area, or they may be scattered around the printing points. The actual printing points are labeled as i, and i = 1, 2, ..., j. Then, the actual printing points that are farthest and closest to the target printing area are obtained and labeled as imax and imin, respectively.

[0010] Next, the specific cause of the deviation is determined based on the farthest printing point (imax) and the nearest printing point (imin), and the deviation of the printer is corrected accordingly. These specific causes may include inaccurate printer calibration, printhead blockage, irregularity of the object surface, or inconsistent relative movement speed between the printer and the object.

[0011] Step Two: Use the offset-corrected inkjet printer to print on the object, and perform positioning analysis based on the changes in the printing area of ​​the object. The specific positioning analysis method is as follows:

[0012] The process involves acquiring the object to be printed and designating it as the target object, along with its target printing area. The target printing area is then compared to the printer's current printing direction, which represents the printing effect corresponding to the printer's current position. For example, if the printer is horizontally or vertically positioned, the corresponding printing direction is horizontal and vertical; if the printer is tilted, the corresponding printing method is tilted. When the target printing area matches the current printing direction, the target object can be printed directly. Conversely, when the printing area differs from the current printing direction, the printer's current printing direction needs to be adjusted. Specifically, the printer's orientation, angle, or position needs to be adjusted to ensure its printing direction perfectly aligns with the target printing area.

[0013] Step 3: When the current printing direction of the inkjet printer needs to be adjusted, acquire the historical data of the inkjet printer, and determine the standard printing direction based on the historical data. The specific determination method is as follows:

[0014] Obtain the printing thickness corresponding to different printing directions in historical data, and classify the different printing directions according to the printing thickness. Specifically, classify them into uniform printing and non-uniform printing. Then obtain all uniform printing directions and record them as n, where n = 1, 2, ..., m. At the same time, obtain the printing angle corresponding to the uniform printing direction and record it as Gn.

[0015] Next, the uniform printing directions are sorted in ascending order according to the printing angle Gn, and the corresponding angle intervals are generated according to the sorting order. At the same time, the median value of the angle interval is selected and used as the standard printing direction.

[0016] Step 4: Next, compare and adjust the obtained standard printing direction with the target printing area, and the specific adjustment method is as follows:

[0017] A coordinate system is established for the target printing area. The X-axis is established with the horizontal plane of the target object as the reference, and the Z-axis is established with the vertical direction of the target object as the reference. This process is repeated to establish the spatial coordinate system of the object to be analyzed. Then, the target printing area is represented using coordinates, specifically the four vertices of the target printing area. The target printing area is then mapped to obtain the mapped coordinates. Details are attached. Figure 3 As shown.

[0018] Next, the current printing direction of the inkjet printer is obtained, and the current printing direction of the inkjet printer is assumed to be the standard printing direction. The difference between the mapped coordinates and the current printing direction is calculated, and the mapped coordinates of the target printing area are at the same height as the current printing direction. The calculated difference is compared with a preset value, and the specific value of the preset value is set by the operator. When the difference is greater than the preset value, it means that the current printing direction is not suitable and further adjustment and positioning are required. Conversely, when the difference is less than the preset value, it means that the current printing direction is suitable, and the adjustment result is generated.

[0019] Step 5: For cases requiring further positioning adjustments, the optimal adjustment parameters are generated by analyzing the angle range. The specific generation method is as follows:

[0020] Obtain the angle range, and select the mapped coordinates and preset values ​​from the angle range to determine the pre-selected angles that meet the conditions. At the same time, generate the pre-selected angle range. Then, label all the pre-selected angles in the pre-selected angle range as a, where a = 1, 2, ..., b, and obtain the printing thickness Ha and adjustment time Ta corresponding to the pre-selected angle a. Here, the adjustment time represents the time required to adjust the printer from the standard printing direction to the pre-selected angle.

[0021] Next, the printing thickness Ha of the pre-selected angle a is analyzed, and the printing thickness Ha that meets the production requirements is selected. At the same time, the corresponding pre-selected angle a is marked as the initial selection angle a1. The printing thickness Ha1 and the adjustment time Ta1 corresponding to the initial selection angle a1 are substituted into the formula Fa1=Ha1+Ta1×θ to calculate the comprehensive value Fa1 corresponding to the initial selection angle a1. θ is a preset proportional coefficient with a value of 1.241. Then, the initial selection angle corresponding to the smallest comprehensive value Fa1 is selected as the standard angle.

[0022] Next, the difference between the current printing direction and the standard angle is calculated, and the current printing direction is adjusted based on the difference, while generating adjustment information.

[0023] Step Six: Analyze the printing results of the inkjet printer on the target object after adjustment, and adjust the inkjet printer accordingly based on the analysis results to generate adjustment parameters. The specific method for generating adjustment parameters is as follows:

[0024] All target objects are acquired and labeled. Then, the printing thickness of all target objects is acquired, which can be measured using laser ultrasound. The printing thickness of all target objects is judged. When the difference between the printing thicknesses is within the allowable range, it means that no adjustment is needed. Conversely, when the difference between the printing thicknesses is not within the allowable range, it means that the printer needs to be adjusted. The allowable range here is a range value. When printing on different target objects, uneven printing may occur due to the machine itself, which requires further adjustment of the machine.

[0025] Next, all printing thicknesses are obtained, and the discrete values ​​of the printing thickness are calculated. The calculated discrete values ​​are used as the standard values ​​of the printing thickness. Then, the parameters of the printer are set according to the standard values ​​of the printing thickness, and the printing speed is adjusted to achieve the standard printing thickness.

[0026] This invention provides a real-time positioning method for printing dots based on optical imaging. Compared with existing technologies, it has the following advantages:

[0027] This invention calibrates and positions the printing points of the inkjet printer, thereby reducing errors in the subsequent printing process. Furthermore, it analyzes the printing area during printing, taking into account the object's placement posture and the inkjet printer's printing direction, to select appropriate printing directions and angles to adapt to the printing requirements of objects with different placement postures, reduce errors in the printing process, and improve printing efficiency.

[0028] This invention also analyzes the printing effect of the printed object, calculates the thickness of the printing ink, and calculates the optimal printing thickness based on the obtained values ​​to address uneven printing. Furthermore, it calculates the adjustment parameters of the printing machine to ensure the overall printing quality. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method of the present invention;

[0030] Figure 2 This is a schematic diagram of the mapping coordinate analysis of the present invention;

[0031] Figure 3This is a schematic diagram of the inkjet dot calibration analysis of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please see Figure 1 , Figure 2 and Figure 3 This application provides a real-time positioning method for printing dots based on optical images, which specifically includes the following steps:

[0034] Step 1: Conduct multiple experiments on the printing dots, and calibrate the accuracy of the printing dots based on the experimental results. The specific calibration method is as follows:

[0035] First, identify the target object, which is a regular-shaped object such as a cube, cuboid, or cylinder. Then, determine the printing area of ​​the target object and record this area as the target printing area. Simultaneously, perform printing processing based on this area to generate multiple sets of actual printing points, as shown in the attached diagram. Figure 2 As shown, the multiple sets of actual printing points obtained may coincide with the printing points corresponding to the printing area, or they may be scattered around the printing points. The actual printing points are labeled as i, and i = 1, 2, ..., j. Then, the actual printing points that are farthest and closest to the target printing area are obtained and labeled as imax and imin, respectively.

[0036] Next, the specific cause of the deviation is determined based on the farthest printing point (imax) and the nearest printing point (imin), and the deviation of the printer is corrected accordingly. These specific causes may include inaccurate printer calibration, printhead blockage, irregularity of the object surface, or inconsistent relative movement speed between the printer and the object.

[0037] Based on practical analysis, assuming printing is being performed on a flat rectangular object, with the printing area set on one face of the object. During the printing process, the actual printheads not only appeared within the predetermined area, but some points also deviated to the top and right of the area. Measurements determined that the farthest printhead was located in the upper right corner of the area, while the nearest printhead was located in the lower left corner. Inspection revealed that the printer's calibration settings were incorrect, causing the printhead angle to deviate from the ideal state. The printer was then recalibrated, and the printhead angle was adjusted to ensure that the printed pattern accurately fell within the predetermined printing area.

[0038] Step Two: Use the offset-corrected inkjet printer to print on the object, and perform positioning analysis based on the changes in the printing area of ​​the object. The specific positioning analysis method is as follows:

[0039] The process involves acquiring the object to be printed and designating it as the target object, along with its target printing area. The target printing area is then compared to the printer's current printing direction, which represents the printing effect corresponding to the printer's current position. For example, if the printer is horizontally or vertically positioned, the corresponding printing direction is horizontal and vertical; if the printer is tilted, the corresponding printing method is tilted. When the target printing area matches the current printing direction, the target object can be printed directly. Conversely, when the printing area differs from the current printing direction, the printer's current printing direction needs to be adjusted. Specifically, the printer's orientation, angle, or position needs to be adjusted to ensure its printing direction perfectly aligns with the target printing area.

[0040] Based on practical analysis, suppose there is a rectangular product packaging box, and product information needs to be printed on the top of the box. This top area is the target printing area. Before printing, it is necessary to confirm that the printhead of the inkjet printer is facing this top area. Place the box under the inkjet printer, and use the positioning system to detect the position of the box. The printing software will automatically analyze the relative position of the target printing area and the printhead of the inkjet printer. If the software determines that the printing direction is correct, that is, the printhead is facing the top of the box, the printing program can be started. However, if the software detects that the printing direction does not match the target printing area, for example, the printhead is facing the side of the box, the operator will receive a prompt and adjust the position of the inkjet printer or the placement of the box until the printing direction is correctly aligned.

[0041] Step 3: When the current printing direction of the inkjet printer needs to be adjusted, acquire the historical data of the inkjet printer, and determine the standard printing direction based on the historical data. The specific determination method is as follows:

[0042] Obtain the printing thickness corresponding to different printing directions in historical data, and classify the different printing directions according to the printing thickness. Specifically, classify them into uniform printing and non-uniform printing. Then obtain all uniform printing directions and record them as n, where n = 1, 2, ..., m. At the same time, obtain the printing angle corresponding to the uniform printing direction and record it as Gn.

[0043] Next, the uniform printing directions are sorted in ascending order according to the printing angle Gn, and the corresponding angle intervals are generated according to the sorting order. At the same time, the median value of the angle interval is selected and used as the standard printing direction.

[0044] Based on actual analysis, assuming the printing system performed hundreds of printing jobs in the past month, with detailed records of printing direction and thickness for each job, analysis of this data revealed that the printing thickness was most uniform when the printing angle was between 30° and 60°. Therefore, we set the midpoint of this range, 45°, as the standard printing direction. In the future, we will prioritize setting the printer angle to 45° to achieve the best printing results.

[0045] Step 4: Next, compare and adjust the obtained standard printing direction with the target printing area, and the specific adjustment method is as follows:

[0046] A coordinate system is established for the target printing area. The X-axis is established with the horizontal plane of the target object as the reference, and the Z-axis is established with the vertical direction of the target object as the reference. This process is repeated to establish the spatial coordinate system of the object to be analyzed. Then, the target printing area is represented using coordinates, specifically the four vertices of the target printing area. The target printing area is then mapped to obtain the mapped coordinates. Details are attached. Figure 3 As shown.

[0047] Next, the current printing direction of the inkjet printer is obtained, and the current printing direction of the inkjet printer is assumed to be the standard printing direction. The difference between the mapped coordinates and the current printing direction is calculated, and the mapped coordinates of the target printing area are at the same height as the current printing direction. The calculated difference is compared with a preset value, and the specific value of the preset value is set by the operator. When the difference is greater than the preset value, it means that the current printing direction is not suitable and further adjustment and positioning are required. Conversely, when the difference is less than the preset value, it means that the current printing direction is suitable, and the adjustment result is generated.

[0048] Based on practical analysis, let's assume the operator sets a preset value of 0.5 mm based on experience. Before a printing job begins, the system detects that the difference between the printer's current printing direction and the standard printing direction (assumed to be 45°) is 0.6 mm, exceeding the preset value. At this point, the printing system will automatically prompt the operator to make adjustments.

[0049] Step 5: For cases requiring further positioning adjustments, the optimal adjustment parameters are generated by analyzing the angle range. The specific generation method is as follows:

[0050] Obtain the angle range, and select the mapped coordinates and preset values ​​from the angle range to determine the pre-selected angles that meet the conditions. At the same time, generate the pre-selected angle range. Then, label all the pre-selected angles in the pre-selected angle range as a, where a = 1, 2, ..., b, and obtain the printing thickness Ha and adjustment time Ta corresponding to the pre-selected angle a. Here, the adjustment time represents the time required to adjust the printer from the standard printing direction to the pre-selected angle.

[0051] Next, the printing thickness Ha of the pre-selected angle a is analyzed, and the printing thickness Ha that meets the production requirements is selected. At the same time, the corresponding pre-selected angle a is marked as the initial selection angle a1. The printing thickness Ha1 and the adjustment time Ta1 corresponding to the initial selection angle a1 are substituted into the formula Fa1=Ha1+Ta1×θ to calculate the comprehensive value Fa1 corresponding to the initial selection angle a1. θ is a preset proportional coefficient with a value of 1.241. Then, the initial selection angle corresponding to the smallest comprehensive value Fa1 is selected as the standard angle.

[0052] Next, the difference between the current printing direction and the standard angle is calculated, and the current printing direction is adjusted based on the difference, while generating adjustment information.

[0053] Step Six: Analyze the printing results of the inkjet printer on the target object after adjustment, and adjust the inkjet printer accordingly based on the analysis results to generate adjustment parameters. The specific method for generating adjustment parameters is as follows:

[0054] Ensuring consistent printing thickness across all objects is crucial in the inkjet printing process. First, all objects need to be numbered for tracking and management. Then, advanced measurement technologies, such as laser ultrasonic testing, allow us to accurately obtain printing thickness data for each object.

[0055] After obtaining the print thickness data, we will analyze it in detail to determine whether the differences between them are within the allowable range. This allowable range is a preset interval that takes into account the thickness unevenness that may occur in different objects during the printing process due to mechanical factors. If the print thickness difference of all objects is within this range, it is considered that no adjustment is needed to the printer; if it exceeds this range, it indicates that corresponding adjustments are required.

[0056] To standardize the print thickness, we calculate the discrete values ​​of all measured print thicknesses, reflecting the fluctuations in print thickness. These discrete values ​​are then used as the standard for print thickness, and the printer parameters are set accordingly. Specifically, we can control the print thickness by adjusting the print speed to meet the standard value.

[0057] Some of the data in the above formulas are numerical calculations with dimensions removed, and the contents not described in detail in this specification are all prior art known to those skilled in the art.

[0058] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A method for real-time positioning of printing dots based on optical imaging, characterized in that, Includes the following steps: Step 1: Analyze the actual printing points obtained from multiple experiments based on the target printing area, and adjust the precision of the printing machine accordingly. Step 2: Use the inkjet printer with the precision adjusted to print on the object, and determine whether to adjust the inkjet printer based on the printing area of ​​the object. Step 3: When adjustments are needed, determine the standard printing direction of the inkjet printer by combining historical data; Step 4: Adjust the current printing direction of the printer based on the target printing area as the standard, and determine whether further adjustment is needed based on the difference in the standard printing direction. Step 5: For cases requiring further adjustment, filter the pre-selected angle range and determine the standard angle based on the printing thickness and adjustment time. Simultaneously, generate adjustment information, and the specific processing method is as follows: Obtain the angle range, select the pre-selected angle from the angle range, and generate the pre-selected angle range. Then, label all the pre-selected angles in the pre-selected angle range as a, where a = 1, 2, ..., b. Obtain the printing thickness Ha and adjustment time Ta corresponding to the pre-selected angle a. The adjustment time is the time required to adjust the printer from the standard printing direction to the pre-selected angle. Next, the printing thickness Ha at the pre-selected angle α is analyzed, and the printing thickness Ha that meets the production requirements is selected. At the same time, the corresponding pre-selected angle α is marked as the initial selection angle α1. The printing thickness Ha1 corresponding to the initial selection angle α1 and the adjustment time Ta1 are substituted into the formula. The comprehensive value Fa1 corresponding to the initially selected angle a1 is calculated, and The preset proportional coefficient is set to 1.

241. Then, the initial angle corresponding to the minimum comprehensive value Fa1 is selected as the standard angle, and the current printing direction of the inkjet printer is adjusted according to the standard angle to generate adjustment information. Step 6: Analyze the printing thickness of the printed object based on the adjusted inkjet printer, and calculate the standard value based on the printing thickness.

2. The real-time positioning method for printing dots based on optical imaging according to claim 1, characterized in that, The precise adjustment of the inkjet printer in step one is as follows: Obtain the printing area of ​​the object to be printed and record the printing area as the target printing area. Then, print multiple times with the target printing area as the object to obtain multiple sets of actual printing points and label them as i, where i = 1, 2, ..., j. At the same time, obtain the actual printing points that are farthest and closest to the target printing area and record them as imax and imin. The specific cause of the deviation is determined by comparing the farthest actual print point (imax) and the nearest actual print point (imin), and the deviation of the printer is corrected accordingly.

3. The real-time positioning method for printing dots based on optical imaging according to claim 1, characterized in that, The specific method for determining whether the inkjet printer needs adjustment in step two is as follows: The object to be printed is designated as the target object, and the printing area of ​​the target object is designated as the target printing area. At the same time, the current printing direction of the printer is obtained, and the target printing area is compared with the current printing direction. When the target printing area is the same as the current printing direction, the target object can be printed directly. Conversely, when the printing area is not the same as the current printing direction, the current printing direction of the printer needs to be adjusted.

4. The real-time positioning method for printing dots based on optical imaging according to claim 1, characterized in that, The analysis of determining the standard printing direction when the inkjet printer needs to be adjusted in step three is as follows: Obtain the printing thickness corresponding to different printing directions in historical data, and classify the printing directions into uniform printing and non-uniform printing according to the printing thickness. Then, obtain all uniform printing directions and record them as n, where n = 1, 2, ..., m. At the same time, obtain the printing angle corresponding to the uniform printing direction and record it as Gn. Next, the uniform printing directions are sorted in ascending order according to the printing angle Gn, and the corresponding angle intervals are generated according to the sorting order. At the same time, the median value of the angle interval is selected and used as the standard printing direction.

5. The real-time positioning method for printing dots based on optical imaging according to claim 1, characterized in that, The specific method for adjusting the current printing direction of the inkjet printer using the standard printing direction as the standard in step four is as follows: Establish the corresponding X, Y, and Z axes based on the length, width, and height of the target object, and establish a spatial coordinate system. Then, obtain the target printing area of ​​the target object, represent the target printing area as coordinate points, and perform coordinate mapping on the target printing area to obtain the mapped coordinates. Next, the current printing direction of the inkjet printer is obtained, and the difference between the mapped coordinates and the current printing direction is calculated. The calculated difference is compared with the preset value. If the difference is greater than the preset value, further positioning adjustment is required. Conversely, if the difference is less than the preset value, the adjustment result is generated.

6. The real-time positioning method for printing dots based on optical imaging according to claim 1, characterized in that, The specific method for analyzing and adjusting the thickness of the printed object in step six is ​​as follows: All printed objects are acquired and labeled, and the printing thickness of each printed object is also acquired. Then, the difference in printing thickness of all printed objects is analyzed, and the difference is compared with the preset value difference. When the difference is less than the preset difference, no adjustment is needed; conversely, when the difference is greater than the preset difference, adjustment is needed.

7. The real-time positioning method for printing dots based on optical imaging according to claim 6, characterized in that, The analysis method for the situation requiring adjustment in step six is ​​as follows: Obtain all printing thicknesses and calculate the discrete values ​​of the printing thickness. Use the calculated discrete values ​​as the standard values ​​of the printing thickness, and then set the parameters of the printer based on the standard values ​​of the printing thickness.

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