Jet control employing substrate alignment features and print area alignment features

Abstract

In a printing method, at least one image of a substrate loaded in a printing system is acquired. Based on the at least one image, an actual position of a first alignment feature on the substrate in a frame of reference of the printing system is determined. An expected position of a second alignment feature on the substrate is determined based on the actual position of the first alignment feature. An actual position of the second alignment feature in a frame of reference of the printing system is determined based on the at least one image and an expected position of the second alignment feature. A target location of a printed area on the substrate is determined based on an actual location of the second alignment feature. And controlling a printing material to be ejected onto the substrate in the printing area based on the target position of the printing area.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 782,442, filed on December 20, 2018, U.S. Provisional Patent Application No. 62 / 891,807, filed on August 26, 2019, and U.S. Non-Provisional Application No. 16 / 716,143, filed on December 16, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0002] In general, embodiments of the present application relate to inkjet printing systems. Specifically, jetting control methods, systems, and / or devices for use in inkjet printing systems are described. Background Art

[0003] Inkjet printing is common in office and home printers, as well as industrial printers used to manufacture displays, print large printed materials, incorporate materials into manufactured products such as PCBs, and construct biological products such as tissues. Some printing applications, such as printing luminescent materials on display substrates, require extremely high positioning accuracy of the dispensing nozzle and / or the printing substrate. In some cases, if the placement error of the droplets of printing material exceeds about 15 μm, printing errors will result. Achieving this extremely high accuracy is affected by numerous factors, such as manufacturing tolerances of printer components, thermal expansion, thermal non-uniformity, vibration, and the evolution of the characteristics of printer components over time. Differences in substrate preparation can also cause errors. In particular, before printing the luminescent material on the display substrate, positioning members of the luminescent material are sometimes printed on the substrate. Variations or errors in the printing position can lead to and compound errors in the printing of the luminescent material. In this regard, methods, systems and / or devices for controlling the ejection of printing material in an inkjet printer are proposed. Summary of the Invention

[0004] In a printing method according to one embodiment, at least one image of a substrate loaded in a printing system is acquired. Based on the at least one image, an actual position of a first alignment feature on the substrate in a reference frame of the printing system is determined. Based on the actual position of the first alignment feature, an expected position of a plurality of second alignment features on the substrate is determined. Based on the at least one image and the expected position of the second alignment features, the actual positions of the plurality of second alignment features in the reference frame of the printing system are determined. Based on the actual positions of the second alignment features, target positions of a plurality of printing areas on the substrate are determined. Based on the target positions of the printing areas, ejection of printing material onto the substrate in the plurality of printing areas is controlled.

[0005] In one embodiment, a printing system includes a substrate support for supporting a substrate; a printhead assembly having a dispensing nozzle; at least one imaging device; and a controller. The controller is configured to control the at least one imaging device to capture a first image of a plurality of first alignment features on the substrate. The controller is further configured to determine, based on the first image, actual positions of the first alignment features within a reference frame of the printing system. The controller is further configured to determine, based on the actual positions of the plurality of first alignment features, expected positions of a plurality of second alignment features. The controller is further configured to control the relative positioning of the at least one imaging device and the substrate support based on the expected positions of the second alignment features, such that the second alignment features can be imaged using the at least one imaging device. The controller is further configured to control the at least one imaging device to capture a second image of the second alignment features. The controller is further configured to determine, based on the second image, actual positions of the second alignment features within the reference frame of the printing system. The controller is further configured to determine, based on the actual positions of the second alignment features, a target position of a printing area corresponding to the group of second alignment features. The controller is further configured to control the dispensing nozzle of the printhead assembly to eject printing material onto the substrate within the printing area based on the target position of the printing area.

[0006] In one embodiment, a controller for a printing system includes at least one processor. The processor is used to receive image data of at least one alignment feature among a plurality of alignment features on a substrate that supports a print job in the printing system. The processor is also used to determine the actual positions of the plurality of alignment features in a reference frame of the printing system based on the image data. The processor is also used to determine the target positions of the pixels at the corners of a printing area on the substrate based on the actual positions of the plurality of alignment features. The processor is also used to determine the target positions of the pixels along the edge of the printing area based on the target positions of the pixels at the corners of the printing area. The processor is also used to determine the target positions of the pixels in the printing area based on the target positions of the pixels along the edge of the printing area. The processor is also used to control the ejection of printing material from a dispensing nozzle of a print head assembly of the printing system onto the substrate in the printing area based on the target positions of the pixels in the printing area.

[0007] In one embodiment, a flat panel display is made by a printing method, wherein at least one image of a substrate loaded in a printing system is obtained; based on the at least one image, the actual position of a first alignment feature on the substrate in a reference system of the printing system is determined; based on the actual position of the first alignment feature, the expected positions of multiple second alignment features on the substrate are determined; based on the at least one image and the expected positions of the second alignment features, the actual positions of the multiple second alignment features in the reference system of the printing system are determined; based on the actual positions of the second alignment features, target positions of multiple printing areas on the substrate are determined; and based on the target positions of the printing areas, the printing material is controlled to be ejected onto the substrate in the multiple printing areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Various aspects of the present disclosure may be better understood with reference to the accompanying drawings and the following detailed description. It should be noted that, in accordance with standard industry practice, the various features are not drawn to scale. In fact, the size of the various features may be arbitrarily increased or decreased for clarity.

[0009] Figure 1 It is a top-down isometric view of the printing system.

[0010] Figure 2 is a schematic top view of a printing system according to one embodiment.

[0011] Figure 3A is a schematic side view of a printing system according to one embodiment.

[0012] Figure 3B In the example Figure 3A Schematic top view of a substrate of a printing system.

[0013] Figure 4 is a flow chart of a printing method according to one embodiment.

[0014] Figures 5A-5D is based on Figure 4 Schematic plan view of a substrate or portion of a substrate processed during the various operations of the printing method shown.

[0015] Figure 6A is a flow chart of a printing method according to one embodiment.

[0016] Figure 6B is based on Figure 6A Schematic plan view of the printing area on the substrate processed by the printing method shown.

[0017] Figure 7 is a flow chart of a printing method according to one embodiment.

[0018] Figure 8is a block diagram of a controller according to one embodiment.

[0019] Figure 9 is a schematic isometric view of a printing assembly according to one embodiment. DETAILED DESCRIPTION

[0020] The present disclosure then provides many different embodiments or examples to implement the different features of the present invention. The specific examples of components, values, operations, materials, configurations, etc. described below are intended to simplify the present disclosure. Of course, these examples are merely exemplary and non-restrictive. Other components, values, operations, materials, configurations, etc. are contemplated. For example, for the purpose of brevity and clarity, the reference numbers and / or letters in the various examples of the present disclosure may be repeated, but the repetition itself does not indicate the relationship between the various embodiments and / or configurations discussed. For ease of explanation, spatial relationship terms such as "below", "below", "lower", "above", "upper", etc. may be used in this article to describe the relationship between an element or feature as shown in the figure and other elements or features. Spatial relationship terms are intended to include different directions when the device is used or operated other than the direction shown in the figure. If the device adjusts its direction (rotates 90 degrees or is in other directions) under other circumstances, the spatial relationship descriptors used in this article will be interpreted accordingly.

[0021] Some inkjet printing applications rely on high-precision positioning of the dispensing nozzle and / or the printing substrate to achieve high-quality printed products. To precisely dispense printing material onto small target locations on a substrate using an inkjet printing system, it is necessary to determine the actual position of the substrate and / or its print area within the inkjet printing system's reference frame. High-precision printing is then performed using the actual position of the print area defined by the printing system's reference frame. The actual position of the print area is determined based on one or more print area alignment features on the substrate. The actual position of the print area alignment features is, in turn, determined based on one or more substrate alignment features. Therefore, in at least one embodiment, the actual position of all print areas on a substrate can be determined within a single reference frame of the printing system. A single "trigger" schedule for a print job can be created to print all print areas on the substrate, while allowing for substrate fabrication and / or printer measurement errors. This improves printing speed and accuracy. This arrangement is superior to other approaches that provide a limited set of markers to determine the position of the substrate, without a separate set of markers to determine the position of each print area, and therefore cannot correct for errors between print areas on the substrate.

[0022] Figure 1 is a top isometric view of the printing system 100 .

[0023] The printing system 100 has a substrate support 102, a printing assembly 104, and a holder assembly 106 for manipulating the printing substrate. The printing system 100 is built on a base 108, which in one example is a massive object to minimize vibration transmission to the operating components of the printing system 100. In one example, the base 108 is a block of granite. The substrate support 102 is located on the base 108 and includes a support surface 110 and a device that makes the support surface 110 substantially frictionless. In one example, the support surface 110 is a pneumatic table that provides an air cushion on which the substrate floats. The support surface 110 has a plurality of holes 112 through which gas jets flow, thereby providing an upward force to maintain the substrate at a desired height above the support surface 110. Some of the holes are also used to controllably exhaust gas from the air cushion that floats the substrate, thereby precisely controlling the height of the substrate locally.

[0024] The printing assembly 104 includes a dispenser assembly 114 disposed on a print support 116. The print support 116 is positioned relative to the substrate support 102 so that the dispenser assembly 114 is structurally positioned relative to the substrate on the substrate support 102, allowing the printing material to be precisely applied to the substrate. The print support 116 includes a guide rail or beam 117 that traverses the substrate support 102, allowing the dispenser assembly 114 to traverse the substrate support 102 and deposit the printing material at any location on the substrate from one side of the print support 116 to the other. In one example, the print support 116 is attached to and extends from the base 108, thereby stably supporting the dispenser assembly 114. Two brackets 120 extend from the base 108 (on opposite sides of the substrate support 102) to the guide rails 117 (which span the substrate support 102). In one example, both the brackets 120 and the guide rails 117 are made of the same material as the base 108. In one example, the bracket 120, the rail 117, the rail 117, and the base 108 are integrally formed from a single piece of granite.

[0025] Dispenser assembly 114 includes at least one printhead assembly 119 and a printhead controller 118. Printhead controller 118 includes electronics and / or sensors for controlling functional parameters of printhead assembly 119, such as the position, timing, duration, type of printed material, and dispensing of printhead assembly 119 along print support 116. Printhead assembly 119 is movable along rails 117 of print support 116 by operation of a print carriage 122, which is coupled to print support 116 to translate printhead assembly 119 along rails 117 from one end to the other. In one example, print carriage 122 is driven by a motor or servo motor. Power and signal conduits are omitted to simplify the drawing.

[0026] substrate ( Figure 1 The substrate support 102 is positioned below the printing assembly 104 by a holder assembly 106. During loading, the holder assembly 106 securely contacts the substrate and moves the substrate along the substrate support 102 to position the substrate relative to the printing assembly 104, which dispenses printing material onto the substrate in a precise manner. The holder assembly 106 is located on one side of the substrate support 102 and extends along the substrate support 102 in a first direction to translate the substrate in the first direction during printing. Figure 1 The first direction is indicated by arrow 124. The first direction 124 is sometimes referred to as the "Y direction" or "scanning direction". The print head assembly 119 moves in a second direction under the guidance of the track 117, which is substantially transverse to the first direction. The track 117 is substantially in the Figure 1 The rails 117 extend in a second direction indicated by arrow 126. The second direction 126 is sometimes referred to as the "X direction" or "cross-scan direction," and the rails 117 are referred to as "X beams." Figure 1 Arrow 125 in FIG. 1 represents a third direction that is substantially transverse to the first and second directions. Third direction 125 is referred to as the "Z direction." The X, Y, and Z directions are axes of a coordinate system (which serves as a reference system for printing system 100), as indicated by arrows 124, 125, and 126. In one example, the origin of the coordinate system is a fixed point, such as a fixed point associated with base 108 or a starting position of dispenser assembly 114.

[0027] The holder assembly 106 is disposed on a holder assembly support 128, which, in one example, is a rail extending substantially along the entire length of the substrate support 102 in a first direction along an edge 130 of the substrate support 102. In one example, the holder assembly support 128 is attached to the base 108, stably supporting the holder assembly 106. In one example, the holder assembly support 128 and the base 108 are made of the same material. In one example, the holder assembly support 128, the base 108, and the print support 116 are integrally formed from a single piece of granite. The holder assembly support 128 is referred to as a "Y-beam." During operation, the holder assembly 106 moves along the holder support 128 to position a securely held substrate at any location on the substrate support 102. The printing assembly 104, for example, by operating the printing assembly controller 118, positions the printhead assembly 119 to contact a precise location on the substrate for dispensing printing material.

[0028] The system controller 129 receives signals from various sensors deployed throughout the printing system 100 and sends these signals to various components of the printing system 100 to control printing. The system controller 129 is operably coupled, for example, via a network, to the printing assembly controller 118 and the fixture assembly controller 131, which controls the operation of the fixture assembly 106. One or more of the substrate support 102, the printing assembly 104, the fixture assembly 106, and other auxiliary systems (e.g., an environmental control system and a materials management system) may have sensors operably coupled to the system controller 129, which transmit signals related to the status of each component to the system controller 129 during printing operations. The system controller 129 includes data and instructions for determining the control signals to be sent to each controlled component of the printing system 100. In one embodiment, two or more of the system controller 129, the printing assembly controller 118, and the fixture assembly controller 131 are integrated into a single controller. In one embodiment, at least one of the system controller 129 , the printing component controller 118 , and the fixed component controller 131 is implemented as several controllers distributed in the printing system 100 and connected to each other via a network. Figure 7 An example configuration of a controller according to one embodiment is described. For the sake of brevity, reference to a “controller” in the following description refers to any one or more controllers in the printing system 100 .

[0029] To achieve precise inkjet printing, droplets of printing material are deposited onto small areas on the substrate. For example, in some cases, droplets of printing material with a diameter of 5-10 μm are deposited onto an area of 10-15 μm on the substrate. This is typically done while the substrate is moving in the Y direction (scanning direction) to minimize printing time. This extremely high precision is affected by many factors, such as minor imperfections in the size and / or position of various parts of the printing system 100, variations in these dimensions with temperature, inaccuracies in the substrate, inaccuracies in the translational speed of the substrate, dispenser assembly 114, and holder assembly 106, and inaccuracies in the distance between the substrate and the printhead assembly 119. For example, if the position of the dispensing nozzle of the printhead assembly 119 within the reference frame of the printing system 100 cannot be accurately understood or controlled, it is difficult to control the droplets of printing material ejected by the dispensing nozzle of the printhead assembly 119, and it is difficult for the droplets of printing material to reach the target location when the substrate is in the correct position. In some aspects, nozzle mapping is required to determine or control the position of the dispensing nozzle in the reference frame of the printing system 100. In other aspects, features of the substrate are identified and mapped into the reference frame of the printing system 100 to compensate for any deviations of the substrate.

[0030] Figure 2is a schematic top view of a printing system 200 according to one embodiment. In one embodiment, the printing system 200 includes one or more features of the printing system 100 described herein.

[0031] Printing system 200 includes a substrate support that supports a substrate in a manner similar to substrate support 102 of printing system 100. For simplicity, Figure 2 The substrate support is not shown in FIG. 2 , but rather the substrate 208 on the substrate support is shown. The printing system 200 also includes a print head assembly 119 having a dispensing nozzle 206. In practice, Figure 2 The dispensing nozzle 206 may not be visible in such a plan view, but for the purpose of illustration, Figure 2 The marking of the dispensing nozzle 206 is shown in FIG. The dispensing nozzle 206 represented by a circle is shown on the upper surface of the print head assembly 119, but in fact the dispensing nozzle 206 is actually located at the same Figure 2 The nozzle surface (not visible) of the print head assembly 119 is opposite the upper surface visible in FIG. Thus, the circle representing the dispensing nozzle 206 shows the location of the dispensing nozzle 206 on the nozzle surface opposite the visible upper surface. The printing system 20 also includes a controller 118 and at least one imaging device 118 coupled to the controller 118.

[0032] exist Figure 2 In an example configuration, the printing system 200 includes two imaging devices, namely a first imaging device 201 and a second imaging device 202. In one example, the first imaging device 201 and the second imaging device 202 both include cameras having a set of image sensors arranged in multiple columns and rows to capture image data. Examples of image sensors include, but are not limited to, CMOS (complementary metal oxide semiconductor) sensors and CCD (charge coupled device) sensors. The first imaging device 201 has a first low resolution and a wide field of view 268. The second imaging device 202 has a second high resolution and a narrow field of view 288. The configuration of the imaging devices described is exemplary, and other configurations are within the scope of the embodiments. In other examples, as long as the imaging device has a sufficiently wide viewing angle and / or a sufficiently high resolution, a single imaging device is sufficient for the image capture described herein. In other examples, imaging devices with adjustable viewing angles and / or adjustable resolutions are used.

[0033] At least one of the first imaging device 201 and the second imaging device 202 is movable relative to the substrate support and, therefore, relative to the substrate 208 on the substrate support. For example, the first imaging device 201 is mounted on the distal end of an arm 262, the proximal end of which is attached to a pivot 264. Pivot 264 is mounted on and slides along a rail 266 supported by one of the brackets 120, namely bracket 120A. Arm 262 can telescope (as indicated by arrow 272) to adjust its length. Arm 262 can also rotate about pivot 264, as indicated by arrow 274, and the proximal end of arm 262 can move along rail 266, as indicated by arrow 276. Similarly, the second imaging device 202 is mounted on the distal end of an arm 282, the proximal end of which is attached to a pivot 284. Pivot 284 is mounted on and slides along a rail 286 supported by another bracket 120, namely bracket 120B. The arm 282 can be telescoped to adjust its length. The described movement of the first imaging device 201 and / or the second imaging device 202 is exemplary, and other configurations are also within the scope of the embodiments.

[0034] The movement of the first imaging device 201 and / or the second imaging device 202 relative to the substrate 208 is controlled by the controller 118 via a precision positioning device such as a servo motor. Therefore, the actual position of the first imaging device 201 and / or the second imaging device 202 in the reference frame of the printing system 200 is known to the controller 118, and the controller 118 can use this actual position to determine the actual position of one or more marks identified from the images captured by the first imaging device 201 and / or the second imaging device 202.

[0035] In one example, a first imaging device 201 with a larger field of view 268 can be used to capture a wide-area intermediate image of substrate 208, thereby increasing the likelihood that the intermediate image will include a mark 290 on substrate 208. Based on the captured wide-area image, controller 118 uses known algorithms, as described herein, to identify mark 290. The actual position of identified mark 290 is determined based on at least the actual position of first imaging device 201 when the wide-area image was captured. However, due to the low resolution of first imaging device 201, in some cases, the actual position of identified mark 290 determined based on this low-resolution wide-area image may not be accurate enough. In such cases, a second imaging device 202 with a higher resolution, under the control of controller 118, is moved to the position of mark 290 in the wide-area image to capture another high-resolution image. This allows for a more accurate determination of the actual position of mark 290 within the printing system's reference frame. The actual position of mark 290 is then used to determine the actual position of one or more printing areas on substrate 208, as described herein. The high accuracy of determining the actual position of mark 290 helps improve printing accuracy.

[0036] In another example, the second imaging device 202 can be moved under the control of the controller 118 so that the expected position of the mark 290 falls within the field of view 288 of the second imaging device 202. The expected position (or predetermined position) of the mark 290 can be known from, for example, pattern data provided to the printing system 200 for a print job to be printed on the substrate 208. In one example, the pattern data includes an ideal or expected position of the feature in the reference frame of the printing system, the ideal or expected position being consistent with ideal or expected position information used to manufacture a previous layer (e.g., a black matrix). The ideal or expected position can be obtained from a CAD (computer-aided design) drawing of the manufacturing substrate.

[0037] If the mark 290 is indeed present within the narrower field of view 288 of the second imaging device 202, the mark 290 can be identified from the high-resolution image captured by the second imaging device 202, and the actual position of the mark 290 can be determined with high accuracy based on at least the actual position of the second imaging device 202 at the time the high-resolution image was captured, without the need to capture another image. However, if the mark 290 is not within the narrower field of view 288 of the second imaging device 202 due to substrate manufacturing errors or mark installation errors, and thus the mark 290 cannot be identified from the high-resolution image captured by the second imaging device 202, the first imaging device 201 with a wider field of view 268 is moved in to capture an intermediate wide-area image for identifying the mark 290, and then the actual position of the mark 290 is accurately determined using the second imaging device 202, as described above.

[0038] The order of using two imaging devices to capture multiple images of a mark described above is exemplary. In other examples, a single imaging device with an adjustable field of view and / or adjustable resolution (e.g., with a zoom function) can be used instead of multiple imaging devices to capture wide-area images and high-resolution images. In another example, a single image with both high resolution and large coverage of the substrate may be sufficient to obtain a high-precision mark without the need for multiple images, as described below with respect to Figure 3A and Figure 3B Description.

[0039] Figure 3A is a schematic side view of a printing system 300 according to one embodiment. Figure 3B In the example Figure 3ASchematic top view of substrate 308 of printing system 300. In one embodiment, printing system 300 includes one or more features of printing system 100 and printing system 200 described herein. In contrast to printing system 200, in which one or more imaging devices each include a set of image sensors arranged in multiple columns and rows, printing system 300 includes at least one line scan imager having image sensors arranged in a row. The printing system may use a method such as that described with respect to Figure 2 The imaging device described with a set of image sensors can also be used as described with respect to Figure 3A and 3B A line scan imager having a row of image sensors is described.

[0040] like Figure 3A As shown, printing system 300 includes substrate support 102, print head assembly 119, and line scan imager 303. Print head assembly 119 is movably coupled to print support 116 and positioned facing substrate support 102. Line scan imager 303 is coupled to print support 116 or print head assembly 119 and also positioned facing substrate support 102. Line scan imager 303 is movable along print support 116.

[0041] The printhead assembly 119 includes a dispensing nozzle 206 extending toward the substrate support 102. The printhead assembly 119 and the line scan imager 303 are positioned facing the print support 102 in a spraying direction 325 in which printing material is ejected from the dispensing nozzle 206 of the printhead assembly 119 onto a substrate 308 of the substrate support 102. The printhead assembly 119 is coupled to the guide rail 117 via an air bearing assembly or other low-friction coupling device (not shown). A linear actuator, such as a motor or other drive, moves the printhead assembly 119 in a cross-scan direction. The linear actuator is coupled between the printhead assembly 119 and one or both of the carriages 120A and 120B. The line scan imager 303 is coupled to a print carriage 322 carrying the printhead assembly 119 and is thus movable along the guide rail 117 of the print support 116 relative to the substrate support 102 along with the printhead assembly 119. Line scan imager 303 is coupled to a rail 313 supported by print carriage 322, and is movable along rail 313, for example, by a motor or servo motor. Thus, for example, controller 118 can control the movement of line scan imager 303 along print support 116 by movement of printhead assembly 119 along print support 116, by movement of line scan imager 303 relative to printhead assembly 119 along rail 313, or by both. In another example, line scan imager 303 is fixed to print carriage 322 and can be moved along print support 116 by movement of print carriage 322 and printhead assembly 119. In another example, line scan imager 303 is coupled to print support 116 and can be moved independently of printhead assembly 119. In another example, printing system 300 includes multiple line scan imagers, such as line scan imager 303, so that multiple images of substrate 308 are captured during a single pass of the line scan imager in the Y direction.

[0042] The line scan imager 303 is used to capture at least one image, the image including at least one mark on the substrate 308. The line scan imager 303 converts the image into data or signals and sends them to the controller 118 or another controller of the printing system 300 (e.g., Figure 1 The controller 118 receives the signal converted into image data, or the image data sent by the line scan imager 303. Based on the image data, the controller 118 determines the actual position of at least one marker, such as Figure 2The actual location of one or more printing areas of the substrate 308 is then determined based on the actual location of the markings, as described herein. The determination of the printing areas is a process for controlling the printing system 300 to perform high-precision printing. Another optional process facilitates nozzle mapping. With respect to nozzle mapping, the printing system 300 includes an imaging device 302 oriented in a Z direction opposite to the jetting direction 325 for capturing at least one image including a plurality of markings on a bottom surface (or nozzle surface) 329 of the printhead assembly 119. The captured image is sent to the controller 118 or another controller of the printing system 300, such as Figure 3A As shown, the controller 118 is connected to the imaging device 302. For example, the controller 118 identifies a mark on the nozzle surface 329 of the print head assembly 119 from the image sent by the imaging device 302, and maps the position of the dispensing nozzle 206 to the reference system of the printing system 300. According to the mapped position (or actual position) of one or more printing areas of the substrate 308 and the mapped position of the dispensing nozzle 206 in the same reference system, the printing material in the dispensing nozzle 206 is controlled to be ejected to the one or more printing areas of the substrate 308. Because the mapped position of the dispensing nozzle 206 and the one or more printing areas reflects the actual position of the dispensing nozzle 206 and the one or more printing areas with high accuracy, the printing accuracy is improved. In an example configuration, the imaging device 302 for nozzle mapping is a line scan imager, which captures an image including the nozzle surface 329 of the print head assembly 119 while the print head assembly 119 passes through the imaging device 302 in the scanning direction (X direction). In at least one embodiment, the imaging device 302 is omitted.

[0043] Figure 3B In the example Figure 3A Schematic plan view of substrate 308 of printing system 300. More specifically, for comparison, Figure 3B The substrates 308 are shown placed side by side (as shown in FIG. Figure 3A The plan view of the spray direction 325 in FIG. 300 is similar to the plan view of the line scan imager 303 (as viewed from the top of FIG. 301 ). Figure 3A A combined view of a planar bottom view of the bottom surface (looking upward in the Z direction).

[0044] The line scanner imager 303 includes a plurality of image sensors 332. Figure 3BIn an exemplary configuration, all image sensors 332 of the line scan imager 303 are arranged in a row, such as line 331, along the cross-scan direction (X direction). In another embodiment (not shown), the image sensors 332 of the line scan imager 303 are arranged in more than one row. For example, the image sensors 332 in the first row serve as primary image sensors for capturing image data, while the image sensors 332 in the second row can serve as redundant or secondary sensors, providing image data in the event of a failure of one or more primary image sensors, or as additional sensors to improve the signal-to-noise ratio of the image data. The image sensors 332 are optoelectronic devices that capture light reflected from the substrate 308 toward the line scan imager 303 and record electrical signals based on the captured light. As the substrate 308 moves relative to and beneath the line scan imager 303 along the scan direction (Y direction), the image sensors 332 capture an image, including one or more markings on the substrate 308, as described herein. In this regard, the image capture performed by the line scan imager 303 is similar to that performed by a copier or scanner employing a similar arrangement of linear light sensors. In order to capture images including marks or features with a size in the range of several microns, for example, 5-10 microns, the image sensor 332 is configured to provide a high resolution of, for example, about 0.1 microns. Examples of image sensors include, but are not limited to, CMOS (complementary metal oxide semiconductor) sensors and CCD (charge coupled device) sensors.

[0045] To capture an image using the line scan imager 303, the line scan imager 303, under the control of the controller 118, is moved in the X-direction to a position where the mark to be captured is likely to fall within the field of view of the line scan imager 303. The line scan imager 303 is then temporarily fixed in the X-direction relative to the substrate support, which then moves the substrate 308 in the Y-direction for image capture to capture the mark. For example, during the movement of the substrate 308 in the Y-direction, the line scan imager 303 passes over the region of the substrate 308 between lines 373 and 374. The width of this region, or the distance between lines 373 and 374, corresponds to the length of line 331 of the image sensor 332 in the X-direction. The controller 118 controls the line scan imager 303 to capture an image of the region 383, 384, and 385 (hereinafter referred to as images 383, 384, and 385) between lines 373 and 374. Image 383 is captured at the location where the mark 520 is expected to be found. Similarly, image 384 is captured at the locations where marks 522 and 560 are expected to be found, and image 385 is captured at the location where mark 562 is expected to be found. The expected locations of the marks on substrate 308 are contained in the pattern data provided to the printing system for printing on substrate 308. This pattern data includes at least print data of the pattern to be printed on substrate 308 as coordinates in the printing system's reference frame. Before capturing the images, controller 118 controls the movement of line scan imager 303 in the X direction based on the pattern data, so that the expected locations of the marks to be imaged fall within the field of view of line scan imager 303. For example, the expected locations of marks 520, 542, 560, and 562 fall within the area between lines 373 and 374. In at least one embodiment, some of images 383, 384, and 385 are combined into a single image. For example, marks 520 and 522 may be contained in one image extending along the Y direction, while marks 560 and 562 may be contained in another image extending along the Y direction. Images captured by the line scan imager 303 in the printing system 300 are used in a manner similar to the use of images captured by the first imaging device 201 and / or the second imaging device 202 of the printing system 200. However, depending on the size or length of the line 331 of the image sensor 332 in the X direction and / or the length of the captured image / area in the Y direction, the line scan imager 303 can capture high-resolution images covering a wide area. Therefore, when using the line scan imager 303, multiple image captures can be avoided, as described in the examples with respect to the first imaging device 201 and / or the second imaging device 202.

[0046] Now describe Figure 3B308, which will be used as an example substrate, is mapped into the reference frame of the printing system according to some embodiments using one or more imaging devices as described with respect to printing system 200 and / or one or more line scan imagers as described with respect to printing system 300. In one example, substrate 308 is a glass substrate, but other materials such as plastic or ceramic may also be used with the various printers described herein.

[0047] Substrate 308 includes at least one substrate alignment feature and a plurality of print area alignment features. An alignment feature can be any feature having one or more known characteristics, indicating at least one of the position or orientation of an object, that can be captured in image data and identified from the captured image data. A substrate alignment feature indicates at least one of the position or orientation of the substrate. A print area feature indicates at least one of the position or orientation of at least one print area on the substrate. For example, an alignment feature can be a marking, sometimes also referred to as a "fiducial mark," having one or more known characteristics, such as pattern, orientation, size, and location on substrate 308. The marking can be attached (e.g., via an adhesive), etched or machined, or printed or coated onto substrate 308. Other methods of providing markings on the substrate can be used. Any number and / or shape and / or material and / or orientation of markings can be used. Any marking can include text, barcodes, company names, and / or logos. A greater number of markings and / or more complex marking shapes increase the accuracy of the print area positions determined using the markings. Alignment features can also include features inherent to or incorporated into substrate 308. In one example, one or more edges and / or one or more corners of substrate 308 can be used as alignment features. In yet another example, features included on substrate 308 during prior processing can be used as alignment features. Examples of such features include pixel wells or sub-pixel wells in the black matrix material, or other pixel or area definitions where the printed material will be deposited. For simplicity only, markings are used as alignment features in the following description of exemplary embodiments.

[0048] exist Figure 3B In an example configuration, the substrate 308 includes one or more substrate marks 501, 511, 521, 531 arranged at one or more corners of the substrate 308 as substrate alignment features. Each substrate mark 501, 511, 521, 531 is in the shape of a cross, and its position and orientation can be known from the pattern data. The substrate marks 501, 511, 521, 531 together accurately indicate the position of the substrate 308 in the reference frame of the printing system. The shape and / or size and / or number and / or orientation and / or substrate alignment of the substrate marks 501, 511, 521, 531 are precisely aligned with the substrate 308. The relative positions within are merely exemplary. Other configurations are also within the scope of various embodiments. For example, assuming that substrate mark 501 has a known spatial relationship with the corresponding corner 301 of substrate 308, a single substrate mark, such as substrate mark 501, may be sufficient to indicate the position of substrate 308. In yet another example, an edge or corner of substrate 308 may serve as a substrate mark. While in some cases only one substrate mark may be sufficient, providing more than one substrate mark on substrate 308 may increase the accuracy of material deposition.

[0049] In addition to the substrate mark, the substrate 308 also includes a plurality of printing area marks for identifying the plurality of printing areas and mapping the plurality of printing areas to the reference frame of the printing system. For the sake of simplicity, the printing area marks are referred to as "marks" in the following description. Figure 3B In an example configuration, the substrate 308 includes seven printing areas sp1 to sp7, each corresponding to, for example, a display panel to be manufactured. In order to identify the location of the printing area, each printing area of the substrate 308 includes one or more markings. Specifically, each of the printing areas sp1 to sp5 is identified by a set or group of four markings at its corners, while the printing areas sp6 and sp7 share a common set of four markings 590, 592, 594, 596 at the corners of their areas. Figure 3B For the sake of simplicity, some reference numerals are omitted. Markings 510, 512, 514, and 516 on the substrate 308 are used to identify the printing area sp1, markings 520, 522, 524, and 526 on the substrate 308 are used to identify the printing area sp3, and markings 560, 562, 564, and 566 on the substrate 308 are used to identify the printing area sp4.

[0050] In some other methods, a limited set of marks is provided to define the entire substrate, without providing a separate set of marks for each printing area. For example, some methods may only include substrate marks 501, 511, 521, 531 on the substrate 308, and then use the substrate marks 501, 511, 521, 531 to calculate the position information of the printing area based on the layout design information of the substrate and assuming that the printing area is perfectly arranged on the substrate as expected. Such methods may not be able to solve and remedy the situation where the printing area cannot be arranged as expected due to, for example, substrate manufacturing errors. For example, Figure 3B As shown, print area sp1 has placement errors compared to other print areas. Placement errors can include XY offset, rotation, scaling, skew, and keystone (imaging perpendicularity) errors. Inaccurate calculated positions of print areas, especially those with placement errors, can affect the printing accuracy of other methods.

[0051] Figure 4is a flow chart of a printing method 400 according to one embodiment. Figures 5A-5D is based on Figure 4 A schematic plan view of substrate 308 or a portion of substrate 308 processed by various operations of the printing method is shown. Printing method 400 may be performed in any of printing systems 100, 200, and 300 by or under the control of at least one controller described herein. In the following description, printing method 400 is referred to as being performed by or under the control of controller 118.

[0052] In operation 405, at least one image of a substrate loaded in the printing system is acquired. For example, the controller 118 acquires at least one image of the substrate 308 loaded in the printing system 200 or 300 from the first imaging device 201 and / or the second imaging device 202 of the printing system 200, or from the line scan imager 303 of the printing system 300, respectively. The at least one image is acquired at the desired location of the target mark. In the following description, the line scan imager 303 is used for image acquisition.

[0053] Figure 5A 308 is a schematic plan view of a portion of the substrate 308 where the substrate mark 501 is located according to the pattern data. An image 506 of the portion of the substrate 308 is collected and sent as a signal or image data to the controller 118 for mark recognition. Figure 5A The intended form of substrate mark 501, shown by the dashed line, has a cross shape. The cross is formed by vertical elements 502 and horizontal elements 503 intersecting at center point 504, with vertical elements 502 and horizontal elements 503 oriented in the Y and X directions, respectively. Based on the pattern data, the XY coordinate system of center point 504 in the printing system's reference system corresponds to the intended position 504A of substrate mark 501. Figure 5A The dashed lines in FIG5 are for illustration purposes and are not captured in image 506. Image 506 is captured by moving line scan imager 303 under the control of controller 118 to a position where substrate mark 501, at its expected position, is likely to fall within the field of view of line scan imager 303, and then capturing image 506. Controller 118 acquires or generates data representing captured image 506 from the transmission of line scan imager 303.

[0054] In operation 415, the actual position of the first alignment feature on the substrate is determined based on the at least one acquired image. Figure 5A, the controller 118 determines the actual location of the substrate mark 501 based on the data representing the image 506. To do so, the controller 118 performs a mark recognition process to identify the substrate mark 501 from the image data using known characteristics of the substrate mark 501 included in pattern data stored in the controller 118 and / or accessible to the controller 118. Image processing algorithms and / or software and / or programs for identifying objects based on known characteristics of the objects, such as pattern, position, size, and / or orientation, are well known in the image processing art and will not be described in detail herein.

[0055] When the substrate mark 501 cannot be identified from the captured image 506, the controller 118 controls the line scan imager 303 to retake the image. In one example, retaking the image involves repositioning the line scan imager 303 to a new position along the X direction to better correspond to the expected position 504A of the substrate mark 501. In another example, retaking the image involves adjusting the resolution and / or field of view of the line scan imager 303 to image a wider area of the substrate 308. When an imaging device, such as a camera, is used for image capture, as described in relation to Figure 2 Then, the controller 118 performs the mark recognition process again to recognize the substrate mark 501 from the recaptured image.

[0056] In at least one embodiment, it may not be necessary to capture the entire mark. Instead, when a portion of the mark is sufficient to determine the mark's location, capturing an image including that portion may be sufficient to delineate the entire substrate. Therefore, as used herein, "one or more images including one or more marks" or similar expressions do not require that the entire mark be captured from the image; rather, capturing a portion that allows the mark to be identified from the captured portion of the image for subsequent determination of the mark's location may be sufficient.

[0057] Identifying a mark means that the controller has determined that an image (single image or composite image) contains a mark. When the controller identifies a mark, it triggers a process to map the mark into the printing system's reference frame by determining the mark's actual position in the printing system's reference frame. As a result of the mark identification and mapping process, the identified substrate mark 501 will be found at its actual position 504B in the printing system's reference frame, regardless of whether the image is re-photographed, as shown in FIG. Figure 5A, as shown by the solid line in . The controller 118 can determine the actual position of the identified substrate mark 501 based on the known actual position of the image captured by the line scan imager 303. The XY coordinate system of the actual position 504B is offset from the XY coordinate system of the expected position 504A. The orientation of the identified substrate mark 501 may also be different from its expected orientation, as shown by the angle α between the vertical element 502 of the identified substrate mark 501 at the actual position 504B and the Y direction. In one example, the image acquisition and mark recognition processing described is performed to obtain more than one substrate mark, such as substrate marks 501, 511, 521, 531 on the substrate 308. In another example, the actual position of one or more other substrate marks 511, 521, 531 is calculated based on the determined actual position of the substrate mark 501 and pattern data including known relationships between the substrate marks. The controller 118 utilizes the determined actual position and / or orientation and / or other actual characteristics of the one or more substrate marks and based on the known relationship between the one or more substrate marks in the pattern data and the substrate 308 to determine the actual position and / or orientation of the substrate 308. The controller 118 may utilize the determined actual position and / or orientation of the substrate 308 to fundamentally adjust the substrate 308 and / or correct the print data of the pattern to be printed on the substrate 308.

[0058] In operation 425, expected positions of a plurality of second alignment features on the substrate are determined based on the actual positions of the first alignment features. For example, the controller 118 calculates the expected positions of the print area marks using the actual positions and / or orientations of the one or more substrate marks 501, 511, 521, and 531 determined in operation 415 and based on a known relationship between the one or more substrate marks and the print area marks in the pattern data. Bilinear interpolation is an exemplary method for calculating the expected positions of the print area marks, which includes one or more interpolation operations, such as translation, rotation, tilt, and scaling.

[0059] Figure 5B 4 shows a schematic plan view of the substrate 308 as determined by the controller 118 as a result of operation 425. Figure 5B In FIG, the actual positions of substrate marks 501, 511, 521, 531 are determined by operation 415 and are shown in solid lines at their actual positions. Print area marks have not yet been identified or mapped and are shown in dashed lines at their respective intended positions. It should be noted that in this example, it is still desirable to Figure 3B The marks 510 , 512 , 514 , 516 corresponding to the offset printing area sp1 are close to the ideal or expected positions defined by the pattern data.

[0060] In operation 435, the actual position of the second alignment feature is determined based on the at least one image and the expected position of the second alignment feature. For example, controller 118 performs a mark recognition process on the area of the image captured in operation 405 where the expected position determined in operation 425 represents the likely location of the print area mark. This is possible if, for example, the image captured by line scan imager 303 in operation 405 is a high-resolution image covering a large area of substrate 308, where substrate 308 has one or more substrate marks and one or more print area marks. As such, the captured image already contains the one or more print area marks, and processing can be performed on the same image without retaking the image. If the captured image does not cover all print area marks, additional images are captured in a manner similar to operation 405.

[0061] The actual positions of the identified printing area marks are determined from the captured image data in a manner similar to operation 415. All printing area marks representing printing areas can be identified, and their actual positions can be determined from the captured image. For example, all printing area marks 520, 522, 524, 526 representing printing area sp3 can be identified, and their actual positions can be determined from the captured image. This configuration provides high-precision printing area clarity. However, in some cases, the actual position of at least one printing area mark representing a printing area can be calculated based on the actual positions of other printing area marks representing the same printing area. For example, some printing area marks 510, 512, 514 representing printing area sp1 are identified, and their actual positions are determined based on the captured image; however, the actual position of the remaining printing area mark 516 representing the same printing area sp1 is calculated based on the actual positions of the other printing area marks 510, 512, 514 that have been determined. This configuration sacrifices some accuracy in printing area clarity to speed up processing. As Figure 3B As shown, when the printing area sp1 is obviously misaligned, this sacrifice of accuracy may affect the printing precision and ultimately the quality of the printed product.

[0062] Figure 5C 4 shows a schematic plan view of the substrate 308 as determined by the controller 118 as a result of operation 435. Figure 5CIn FIG. 4 , after operations 415 and 435 , all substrate marks and print area marks have been mapped into the reference frame of the printing system and are shown in solid lines at their actual locations. Since the print areas represented by the print area marks have not yet been obtained, they are shown in dashed lines. In other words, the coordinates of each print position within each print area in the reference frame of the printing system have not yet been determined. The controller 118 has now determined and may have quantified and / or marked that the print area sp1 is not at its expected location ( Figure 5B ), but it is actually placed in the wrong place ( Figure 5C As described herein, this detected placement error of the printing area sp1 allows the controller 118 to make corrections to improve printing accuracy. In at least one embodiment, not all printing area marks are processed simultaneously. For example, the printing area marks corresponding to the printing area sp1 and the printing area sp2 are processed first, so that printing can be performed in the printing areas sp1 and sp2. While the printing operation is being performed on the printing areas sp1 and sp2, the printing area marks corresponding to the next printing areas to be printed, i.e., the printing areas sp3 and sp4, are mapped, and so on. This configuration reduces the processing time and printing time of the entire substrate 308 by operating in parallel.

[0063] In operation 445, based on the actual position of the second alignment feature, the target positions of the plurality of printing areas on the substrate are determined. As used herein, the "target position" of a printing area or pixel is the actual position of the printing area or pixel in the reference frame of the printing system, and the position at which the print head assembly of the printing system deposits the printing material. The pattern data may include a coordinate diagram that presents the expected position of the mark and at least the corners of the corresponding printing area, for example, as an XY coordinate system in the reference frame of the printing system or substrate. Taking the printing area sp3 as an example, once the controller 118 maps the marks 520, 522, 524 and 526, the actual positions of the marks 520, 522, 524 and 526 are compared with their known / expected positions in the pattern data. By comparison, the controller 118 obtains a conversion relationship between the positions of the marks 520, 522, 524 and 526 determined from the captured image and their known / expected positions in the pattern data. The controller 118 uses the obtained relationships and the expected positions of the corresponding corners 540 , 542 , 544 , and 546 of the print area sp3 in the pattern data to determine the actual positions of the corners 540 , 542 , 544 , and 546 of the print area sp3 in the reference frame of the printing system.

[0064] Then, the controller 118 determines the actual positions of all pixels to be printed in the printing area sp3 based on the actual positions of the corners 540, 542, 544, and 546. An example method for determining the actual positions of pixels based on the corners is bilinear interpolation, including one or more interpolation operations, such as translation, rotation, tilt, and scaling. Alternatively, in a thin film encapsulation (TFE) application, where the film is to be deposited on the printing area sp3 instead of printing individual pixels, the controller 118 determines the actual position of the boundary of the printing area sp3 based on the actual positions of the corners 540, 542, 544, and 546. The determination of the actual position of the mark, printing area corner, pixel, or boundary in the reference system of the printing system is also referred to as mapping in this article. In some embodiments, the controller 118 performs nozzle mapping in a similar manner to determine the actual position of the dispensing nozzle of the print head assembly 119 based on the nozzle surface mark (not shown) contained in the nozzle surface 329 and one or more images containing the nozzle surface mark taken by the imaging device 302.

[0065] Figure 5D 4 shows a schematic plan view of the substrate 308 as determined by the controller 118 as a result of operation 445. Figure 5D In the example, all substrate markings, print zone markings, and print zones have been mapped in operations 415, 435, and 445 and are shown as solid lines at their actual or target locations. This is merely an example. As described above, one or more print zones may be processed while a print operation is being performed in one or more other print zones.

[0066] Although in the above description, the identification and mapping of printing areas involves collecting and processing marks for each printing area separately, the present disclosure is not limited thereto. For example, the definition of a printing area may involve collecting and processing a set of marks 590, 592, 594, 596 that are common to several printing areas, such as Figure 5D When all common markers 590, 592, 594, 596 have been acquired and identified, the actual positions of the pixels or boundaries of the printing areas sp6 and sp7 are determined, for example, by interpolation, based on the actual positions of the common markers 590, 592, 594, 596 and based on the pattern data indicating the expected positions or relationships of the printing areas sp6 and sp7 relative to the markers 590, 592, 594, 596.

[0067] In operation 455, based on the established target position of the printing area, the printing material is controlled to be ejected onto the substrate in the plurality of printing areas. For example, based on the actual position of the pixel point or boundary of the printing area sp3 in the reference system of the printing system and / or the actual position of the dispensing nozzle of the print head assembly 119 in the reference system of the printing system, the controller 118 controls the printing material to be ejected from the dispensing nozzle of the print head assembly 119 to the printing area sp3 of the substrate 308. In one embodiment, the printing material ejection control includes physical adjustment of the substrate 308 and / or the print head assembly 119, and / or logical modification of the printing data for generating a control signal for the dispensing nozzle to eject the printing material. Since the determined actual position of the dispensing nozzle and / or the printing area sp3 accurately reflects the real physical position of the dispensing nozzle and the printing area sp3, the printing accuracy is improved.

[0068] Specifically, the actual position of the dispensing nozzle and the printing area are in the same reference frame of the printing system and are used by the controller 118 to control when and / or which dispensing nozzle to eject the printing material based on the pattern data, which includes coordinates in the reference frame of the printing data or substrate. For example, if the position of the printing nozzle is found to be different from its expected position by a distance d, then the ink droplets ejected according to the existing printing plan will arrive at a position that is different from its target position t by a distance d. If the distance d has an x-component (the distance in the X direction) d x , you can adjust the print head assembly -d x To compensate. If the printing nozzle is at an average distance in the X direction deviates from its intended position, the printed component can be adjusted To compensate. If the distance d has a y-component d y , you can use the global delay trigger d y / v To adjust the printing plan, where v is the translation speed of the substrate in the Y direction, and the average distance of the y-vector is This allows for the production of printed products with high printing accuracy.

[0069] In one embodiment, printed products manufactured by the printing method include, but are not limited to, solar panels and flat panel displays, such as organic light emitting diode (OLED) displays.

[0070] Figure 6A is a flow chart of a printing method 600 according to one embodiment. Figure 6B is based on Figure 6A The schematic plan view of the printing area sp3 on the substrate 308 processed by the printing method 600 is shown. Figure 6BThe printing method 600 can be executed in any of the printing systems 100, 200, and 300 by or under the control of at least one controller described herein. In the following description, the printing method 600 is executed by or under the control of the controller 118. In one embodiment, the printing method 600 includes one or more features of the printing method 400 described herein.

[0071] In operation 605, at least one image including the alignment features on the substrate is acquired. For example, in a manner similar to operation 405 in the printing method 400, the controller 118 acquires at least one image including one or more marks from the first imaging device 201 and / or the second imaging device 202 of the printing system 200 or the line scan imager 303 of the printing system 300.

[0072] In operation 615, actual positions of the plurality of alignment features in the reference frame of the printing system are determined based on the at least one image. For example, the controller 118 determines the actual positions of the marks 520, 522, 524, and 526 representing the printing area sp3 from the captured image in a manner similar to operations 415 and / or 435 in the printing method 400.

[0073] In operation 625, target positions of pixels at corners of the printed area on the substrate are determined based on the actual positions of the alignment features. For example, the controller 118 compares the actual positions of the markers 520, 522, 524, and 526 with their predetermined positions in the pattern data, thereby obtaining a relationship or conversion function between the actual positions of the markers 520, 522, 524, and 526 (e.g., determined based on the captured image) and their predetermined positions in the pattern data. The controller 118 uses the obtained conversion function and the predetermined positions of the corners 540, 542, 544, and 546 in the pattern data to determine the actual positions of the corners 540, 542, 544, and 546.

[0074] In operation 635, the target positions of the pixels on the edge of the printing area are determined based on the target positions of the pixels at the corners of the printing area. Figure 6B As shown, the controller 118 determines the first side 620 of the printing area sp3 based on the actual positions of the corners 540 and 546, determines the second side 630 of the printing area sp3 based on the actual positions of the corners 540 and 542, determines the third side 640 of the printing area sp3 based on the actual positions of the corners 542 and 544, and determines the fourth side 650 of the printing area sp3 based on the actual positions of the corners 544 and 546.

[0075] For TFE applications, the controller 118 may now proceed to operation 655 to control the print head assembly to deposit a thin film on the print area sp3 within the boundaries defined by the identified edges 620, 630, 640, 650 of the print area sp3.

[0076] For printing at a single pixel in the print area sp3, the controller 118 determines the actual positions of the pixels 622 and 624 on the first side 620 based on the number of pixels in each row of the print area sp3 in the X direction in the image data (e.g., evenly distributing the pixels along the first side 620). Similarly, the controller 118 determines the actual positions of the pixels 642 and 644 on the third side 640 based on the same number of pixels in each row.

[0077] In operation 645, the target position of the pixel point in the printing area is determined based on the target position of the pixel point along the edge of the printing area. Figure 6B As shown, the controller 118 determines the actual positions of pixels 631 and 671 on the determined second side 630 based on the number of pixels in each column of the print area sp3 in the Y direction in the pattern data. Similarly, the controller 118 determines the actual positions of pixels 636 and 676 on the determined fourth side 650 based on the same number of pixels in each column. For pixels within the print area sp3, the controller 118 first determines a column 660 of pixels based on the determined pixels 622 and 642 on the corresponding first and third sides 620 and 640. The controller 118 then determines the actual positions of pixels 632 and 672 on the determined column 660 based on the number of pixels in each column. Similarly, the controller 118 determines a column 670 of pixels based on the determined pixels 624 and 644 on the corresponding first and third sides 620 and 640. The controller 118 then determines the actual positions of pixels 634 and 674 on the determined column 670 based on the number of pixels in each column. The above process is repeated until the actual positions of all pixels in the printing area sp3 are determined.

[0078] In at least one embodiment, operations 625 , 635 , 645 of printing method 600 are performed in operation 445 of printing method 400 to determine a target position of the print area on the substrate based on the actual position of the print area mark.

[0079] In operation 655 , based on the target position of the pixel point in the printing area, the printing material is controlled to be ejected from the dispensing nozzle of the print head assembly onto the substrate in the printing area. For example, the controller 118 controls the ejection of the printing material in a manner similar to operation 455 in the printing method 400 .

[0080] Figure 7is a flow chart of a printing method 700 according to one embodiment. The printing method 700 can be executed in any of the printing systems 100, 200, and 300 by or under the control of at least one controller described herein. In the following description, the printing method 700 is executed by or under the control of the controller 118. In one embodiment, the printing method 700 includes one or more features of the printing methods 400 and 600 described herein.

[0081] In operation 705, at least one imaging device is controlled to capture a first image of a plurality of first alignment features on the substrate. For example, the controller 118 controls the first imaging device 201 and / or the second imaging device 202 to capture one or more first images including the substrate marks 501, 511, 521, and 531 on the substrate 308 in a manner similar to operation 405 in the printing method 400 described above.

[0082] In operation 715, based on the first image, the actual position of the first alignment feature in the reference frame of the printing system is determined. For example, the controller 118 performs a mark recognition process on the acquired first image to identify substrate marks 501, 511, 521, 531 from the acquired first image, and then determines the actual position of the identified substrate marks in a manner similar to operation 415 in the printing method 400. In some cases, multiple image acquisitions are performed by multiple imaging devices, such as with respect to Figure 2 Description.

[0083] In operation 725 , the controller 118 determines the expected positions of the plurality of second alignment features based on the actual positions of the plurality of first alignment features. For example, the controller 118 determines the expected positions of the print zone marks based on the actual positions of the substrate marks in a manner similar to operation 425 in the printing method 400 .

[0084] In operation 727, based on the expected position of the second alignment feature, the relative position of the at least one imaging device and the substrate support supporting the substrate is controlled so that the second alignment feature is imaged using the at least one imaging device. For example, the controller 118 controls the first imaging device 201 and / or the second imaging device 202 so that the one or more expected positions of the one or more print area marks determined in operation 725 fall within the field of view of the first imaging device and / or the second imaging device 202.

[0085] In operation 729, the at least one imaging device is controlled to capture a second image of the second alignment feature. For example, after the repositioning in operation 727, the controller 118 controls the first imaging device 201 and / or the second imaging device 202 to capture one or more second images including the expected location of the one or more print area marks.

[0086] In operation 735, the actual position of the second alignment feature in the reference frame of the printing system is determined based on the second image. For example, the controller 118 performs mark recognition processing on the second image acquired in operation 729 to identify one or more print area marks from the acquired second image, and then determines the actual position of the identified print area marks in a manner similar to operation 715. In some cases, multiple image acquisitions are performed by multiple imaging devices, such as with respect to Figure 2 Description.

[0087] In the event that the field of view of the first imaging device 201 and / or the second imaging device 202 is not wide enough to capture one or more print area marks and / or substrate marks in the first image, at least one imaging device may be repositioned according to operation 727 and subsequent images may be captured according to operation 729. Figure 4 The image captured by a line scan imager such as the line scan imager 303 can cover a sufficiently wide area of the substrate 308 to capture the target mark, and a separate image capture process can be avoided.

[0088] In operation 745, a target position of a print area corresponding to the second set of alignment features is determined based on the actual position of the second alignment features. For example, the controller 118 determines the target position of the print area based on the actual position of the corresponding set of print area marks in a manner similar to operation 445 and / or operations 625, 635, and 645.

[0089] In operation 755 , the printing material is ejected from the dispensing nozzle of the print head assembly onto the substrate in the printing area based on the target position of the printing area. For example, the controller 118 controls the ejection of the printing material in a manner similar to operation 455 .

[0090] In some cases, a line scan imager may be used to calibrate the position of the substrate on the substrate support 102 ( Figure 1). Thus, instead of performing the above-described operation 755, or in addition to performing the above-described operation 755, a repositioning operation may be performed to improve the position of the substrate on the substrate support. In one example, the actual position of the substrate mark can be compared with the expected position of the substrate mark based on the pattern data of the substrate, and a deviation parameter can be determined using any controller or processor described herein. The deviation parameter can be determined in a variety of ways. In one example, the deviation of each substrate mark from its designed position can be determined, and the deviation parameter can be set to a maximum deviation. In another example, the deviation parameter can be set to an average deviation. In another example, the deviation parameter can be set to a deviation of a predetermined substrate mark.

[0091] The deviation parameter is then compared to the tolerance to determine whether the substrate needs to be repositioned. Any controller or processor described herein can perform this comparison. If substrate repositioning is necessary, the printing system is controlled to perform the standard substrate positioning procedure again. This process can be repeated until the deviation parameter is within tolerance, at which point operation 755 described above can be performed.

[0092] The described methods include example operations, but they do not necessarily need to be performed in the order shown. Operations can be added, replaced, changed in order, and / or deleted as appropriate within the spirit and scope of the embodiments of the present disclosure. Embodiments composed of different features and / or different embodiments are also within the scope of the present disclosure and will be apparent to those of ordinary skill in the art after reading this disclosure.

[0093] Figure 8 is a block diagram of a controller according to one embodiment. Figure 8 One or more controllers 800 to implement Figure 1-7 One or more devices and / or systems and / or operations described in.

[0094] The controller 800 includes a hardware processor 802, a storage device 804 including at least one non-transitory computer-readable storage medium, a bus 808, an I / O (input / output) interface 810, and a network interface 812. The processor 802 is coupled to the storage device 804, the I / O interface 810, and the network interface 812 via the bus 808. The network interface 812 can be connected to a network 814, so that the processor 802 and the storage device 804 can communicate with other devices via the network 814. The processor 802 is used to execute computer program instructions encoded in the storage device 804 and / or access data stored in the storage device 804, so that the controller 800 performs operations related to Figure 1-7 One or more functions and / or operations described.

[0095] Processor 802 includes one or more of a central processing unit (CPU), a multi-processor, a distributed processing system, an application specific integrated circuit (ASIC), and / or a suitable hardware processing unit.

[0096] The storage device 804 includes one or more electronic, magnetic, optical, electromagnetic, infrared, and / or semiconductor systems (or devices or apparatuses) for non-transitory storage of instructions and / or data. For example, the storage device 804 includes semiconductor or solid-state memory, magnetic tape, removable computer diskette, random access memory (RAM), read-only memory (ROM), hard disk, and / or optical disk. As examples of optical disks, the storage device 804 includes a compact disk-read only memory (CD-ROM), a compact disk-read / write (CD-R / W), and / or a digital versatile disk (DVD).

[0097] The I / O interface 810 is a circuit that can be connected to an external circuit. For example, the I / O interface 810 includes one or more of a keyboard, a keypad, a mouse, a trackball, a touchpad, cursor direction keys, a card reader, a communication port, a display, a signal light, a printer, and / or an audio device, and is used to exchange information with the processor 802. In one example, the I / O interface 810 is omitted.

[0098] Network interface 812 is a circuit that allows controller 800 to communicate with network 814, to which one or more other controllers and / or image acquisition / processing devices are connected. For example, network interface 812 may include one or more wireless network interfaces such as Bluetooth, WIFI, WIMAX, GPRS, and WCDMA, or wired network interfaces such as ETHERNET, USB, or IEEE-1394. In one example, network interface 812 is omitted.

[0099] By implementing Figure 1-7 Some or all of the functions and / or operations described above, the controller 800 can implement Figure 1-7 One or more of the advantages and / or effects described.

[0100] If the layout of the substrate is known in advance so that the printing system can be configured to utilize the substrate layout, alignment features on the substrate can be quickly located. If a series of substrates with similar or identical layouts are to be processed, the printing system can be configured to quickly locate the alignment features on successive substrates by positioning and activating the camera to focus on the likely location of the alignment features.

[0101] In one instance, a substrate has six panels defined across the width of the substrate. The panels can define a single display device to be formed on the substrate or a group of display devices to be formed on the substrate. The supplementary figures attached in the Appendix to this application summarize the configuration of a printing system camera to quickly acquire and locate alignment marks for such a substrate. Here, the substrate has one or more first alignment features, sometimes also referred to as fiducial marks, and each panel on the substrate is defined using one or more second alignment features. Because it is known in advance that the substrate has six panels of substantially the same size and shape evenly spaced across the width of the substrate, the camera or line imager can be positioned along the printing support, as described herein, and actuated to locate the first alignment feature and the second alignment feature.

[0102] In this case, a first camera system comprising one or more cameras captures a wide image of one or more areas of the substrate. The substrate is scanned from an input side of the printing system to an output side of the printing system to perform a first scan, with the first camera system capturing a first image or multiple first images of the substrate during the first scan. The first scan captures images of at least two first alignment features and may also capture one or more second alignment features. The first scan may capture an image of the entire substrate, or the first scan may capture only areas of the substrate where the first alignment features are expected to be found. Thus, a single first image may include more than one first alignment feature captured and logically combined from multiple images, or the first scan may capture multiple first images.

[0103] A substrate is typically positioned at the input of a printing system for processing. The substrate rests against a positioning feature, such as a physical post or bank, which initializes the position of the substrate. A substrate positioning system is securely coupled to the substrate for further positioning. The substrate typically has opposing first and second ends and opposing first and second sides. The first end of the substrate passes through each imaging system and then the second end passes through each imaging system. As described above, the first image or images include at least two first alignment features and may include more than two first alignment features. If the two first alignment features are located at the first end of the substrate, then the first scan may only partially scan the substrate, imaging only the first alignment features that are expected to be found near the first end.

[0104] In one scenario, the first alignment features are expected to be located near the corners of the substrate. Therefore, wide-area cameras can be positioned on either side of the substrate processing surface of the printing system to capture wide-area images of the substrate near these expected locations. Each wide-area camera has a sufficiently large field of view to eliminate potential errors in positioning the first alignment features, so the wide-area cameras will almost certainly capture the first image (or images). In one embodiment, the positioning error of the first alignment features is approximately 2 mm, and wide-area cameras with a field of view of 10-13 mm are used.

[0105] The first image (or images) is analyzed using image processing software to identify alignment features therein. The image processing software searches for the first alignment feature based on a local search informed by an expected position of the first alignment feature. The expected position is defined as a coordinate in a first coordinate system defined by the printing system, as described elsewhere herein, and is based on a predefined layout of the substrate, which layout includes the coordinates of the alignment features in a second coordinate system defined by the substrate. When the substrate is loaded into the input side of the printing system, a mathematical transformation that relates the second coordinate system to the first coordinate system is based at least in part on the starting position of the substrate. Therefore, by converting the coordinates of the alignment features from the predefined layout to the first coordinate system using a mathematical transformation, the expected positions of all alignment features, including the first alignment feature and the second alignment feature, are known.

[0106] By determining the x-coordinate and y-coordinate of each first alignment feature, the image processing software determines at least the alignment of the first alignment features. As described herein, the y-direction is the scanning direction of the substrate, and the x-direction is the direction perpendicular to the y-direction within the plane of the substrate. If the first alignment features should have the same x-coordinate value, the degree to which the x-coordinates of the first alignment features differ indicates a rotation error of the substrate. As described elsewhere herein, the substrate positioning system is operable to incrementally rotate the substrate to align the x-coordinates of the first alignment features based on an alignment error determined from processing one or more images of the substrate. The rotation angle can be defined as the difference in the x-coordinates of the first alignment features divided by the difference in the y-coordinates of the first alignment features, expressed in radians. The positioning system can also position the substrate to correct for a global x-error of the substrate within a range of deviations between the aligned x-coordinates of the first alignment features and the expected position of the substrate in a predefined substrate processing recipe. Alternatively, the position of the camera can be adjusted for the global x-error of the substrate to capture images of the alignment features.

[0107] The positioning system can also be used to position the substrate or a portion of the substrate in the z direction, which is a direction substantially perpendicular to the substrate processing surface of the printing system (and perpendicular to the x and y directions). The positioning system may have a precision z-actuating component, such as a z-axis linear actuator connected to the substrate engaging portion of the positioning system, to perform z-direction positioning of the substrate portion engaged with the positioning system. In many cases, the substrate engages with the positioning system at the edge of the substrate, so that the z-actuating component positions the edge of the substrate in the z direction. This can serve to at least slightly position the entire substrate in the z direction and / or position the edge of the substrate in the z direction. In many cases, the substrate floats on an air cushion that precisely defines the gap between the substrate and the substrate processing surface, regardless of the movement of the positioning system. The air cushion and the positioning system work together to precisely position the substrate above the substrate processing surface at a distance predefined in the substrate processing solution, and can flatten the substrate with high precision over the entire range of the substrate, including the edge portion where the positioning system engages the substrate.

[0108] The image processing and alignment operations described above can be performed while the substrate is positioned at the output side of the printing system after the first scan. If the substrate is not fully scanned to the output side of the printing system during the first scan, the substrate can remain in a partially scanned position while image processing and alignment are performed, or the substrate can be moved back to the input side of the printing system for alignment. After the substrate is conditioned and positioned according to the substrate processing plan, a second scan is performed, wherein the positioning system moves the substrate from the output side to the input side of the printing system, or vice versa. During the second scan, a second camera system including one or more cameras captures multiple second images of the substrate. Each camera of the second camera system is positioned based on the expected position of the one or more second alignment features, and the expected position in the predefined substrate layout is corrected based on the alignment operations performed after the first scan.

[0109] The second camera system has high-magnification cameras to capture high-resolution images of the second alignment features. In one embodiment, the field of view of the high-magnification cameras is approximately 1 mm, so each high-magnification camera can capture alignment features that are less than 1 mm in size, and if the alignment features are spaced less than 1 mm apart, more than one alignment feature may be captured in a single scan. Typically, when scanning a substrate, the cameras of the second camera system are activated when the alignment feature to be imaged enters the field of view of one of the cameras of the second camera system and are deactivated when the alignment feature is expected to disappear from the field of view. The predefined layout of the substrate is used to determine the expected arrival time of the alignment features within the camera's field of view, and corrections are made for any positioning of the substrate performed during calibration.

[0110] The second scan captures images of all second alignment features. However, in some cases, a single scan may not capture all second alignment features. For example, if some second alignment features are too close together to be imaged by a single camera at the speed of the second scan, one or more second alignment features may be missed during the second scan due to the camera's cycle time. A third scan may be required to capture those missed second alignment features. In this case, an alternative approach is to slow down the scan speed so that all features can be imaged in a single scan. Another option is to use multiple cameras to image the alignment features in a column.

[0111] Each second image is processed by image processing software to determine the actual position of at least two second alignment features for each panel defined on the substrate. Because the layout of the substrate is typically known in advance, a camera of the second camera system is deployed to capture an image of each panel defined on the substrate. Therefore, each camera of the second camera system captures an image of at least two alignment features for each panel defined on the substrate. The cameras of the second camera system are high-power cameras with a limited field of view, but because the substrates are aligned, the expected positions of the second alignment features in the predefined layout are used to position the cameras of the second camera system, and each second image contains a high-resolution image of at least one second alignment feature. The precisely determined actual positions of the second alignment features are used to adjust the printing plan to account for any errors in positioning the panels on the substrate.

[0112] In cases where six panels are defined across the width of the substrate, the second camera system can include six high-magnification cameras positioned at locations on the substrate where second alignment features are expected to appear. During the second scan, each camera of the second camera system captures one or more images of the substrate while scanning the substrate. If desired, image processing software can be used to logically stitch the multiple images together, or capture images only near the expected locations of the alignment features, resulting in gaps between the image locations. Regardless, the six high-magnification cameras capture images of at least two second alignment features for each panel defined on the substrate. Capturing more than two images of the second alignment features for each panel increases the certainty of panel positioning and system calibration.

[0113] It should be noted that a printing system configured with a single camera can be used to align and calibrate the printing system with substrates having different layouts and sizes. In general, if the printing system has n high-magnification cameras and the substrate has m panels, where m is less than n, the substrate with m panels can be aligned and calibrated with the printing system. Because the travel range of the high-magnification cameras is known and the cameras can be positioned based on the known travel range, if there are as many cameras as there are panels, the cameras can be positioned at the desired location x of the alignment feature. This is also true for substrates with sections having different panel layouts. For example, a substrate may have a first section defining three panels and a second section defining six panels. A portion of the six high-magnification cameras of the second camera system, in this example, three cameras, can be used to image the second alignment features of the three panels of the first section, while all cameras can be used to image the second alignment features of the panels of the second section. If the second section has fewer panels than the total number of cameras in the second camera system, a second portion of the cameras of the second camera system can be used to image the second alignment features of the panels of the second section.

[0114] The first and second camera systems are each coupled to the print support substantially as described elsewhere herein. Each camera has a carriage that is connected to a rail on the print support. The print support may define two rails, with each camera system supported by one rail. Alternatively, both camera systems may be supported by only one rail. In the dual-rail scenario, the camera of the first camera system may be coupled to and driven along the first rail, while the camera of the second camera system may be coupled to and driven along the second rail. Thus, the range of motion of each camera of the first camera system is limited by the range of motion of the adjacent cameras. However, since the cameras of the first camera system are wide-angle cameras, the first image can be captured by positioning the cameras of the first camera system at the location where the first alignment feature is expected to appear. The same applies to the cameras of the second camera system. If a portion of the substrate has a different panel layout, requiring repositioning of the cameras during the second scan, the cameras of the second camera system may also be repositioned during the second scan. In some cases, the cameras of the second camera system may be slightly moved during the scan to capture images of the second alignment feature with a near x-coordinate.

[0115] Figure 9FIG2 is an isometric diagram of a printed assembly 900 according to one embodiment. Printed assembly 900 includes multiple cameras deployed in a first camera system 902 and a second camera system 904. Printed assembly 900 can be used to implement the embodiments described above using the first and second camera systems. First camera system 902 includes multiple first cameras 906, and second camera system 904 includes multiple second cameras 908. First cameras 906 and second cameras 908 can be the same type of camera or different types of cameras. In one embodiment, first camera 906 is a wide-angle camera, and second camera 908 is a high-resolution camera.

[0116] The printing assembly 900 has a printing support 910 similar to Figure 1 The guide rail 117 in the printing support 910 supports the first camera 906 and the second camera 908 to span the substrate 912 supported by the substrate support 914 below the printing support 910. Not shown here, the dispenser assembly 114 can be coupled to the printing support 910, such as Figure 1 Note: The dimensions of the printing support 910, substrate 912, and substrate support 914 are shown truncated.

[0117] A first camera 906 and a second camera 908 are coupled to and supported by print support 910 in a spaced relationship from substrate support 914, thereby providing clearance between print support 910 and the device supported by substrate 912. Cameras 906 and 908 are each coupled to a camera bracket 916. Camera brackets 916 coupled to first camera 906 are each coupled to a first rail of print support 910 (not visible here, but may be a recessed groove located in the underside surface of print support 910 facing substrate support 914). Camera brackets 916 coupled to second camera 908 are similarly coupled to a second rail of print support 910. Camera brackets 916 are configured to move relative to each other on the two rails without interfering, thereby enabling the first camera 906 and the second camera 908 to be positioned along print support 910 without interference between either first camera 906 or second camera 908. This allows the first camera 906 to be moved and positioned at any desired location relative to the substrate 912, while also allowing the second camera 908 to be positioned at any desired location independent of the first camera 906. Typically, each camera mount 916 has an actuator, such as a driven wheel or air bearing, that engages a groove or shelf formed in the lower or upper surface of the support 910 to provide positioning capabilities. The cameras 906 and 908 are coupled to the camera mount 916 in an orientation that allows the field of view of each camera 906 and 908 to encompass a portion of the substrate 912. It should be noted that some cameras 906 and 908 may be fixed to the print support 910 and immovable relative to the print support 910, but at least some cameras 906 and 908 may be movable relative to the print support 910. For example, the outer cameras of each camera group may be fixed, while the cameras between the outer cameras may be actuated.

[0118] The features of several embodiments are summarized above so that those skilled in the art can better understand the aspects of the present disclosure. It should be understood by those skilled in the art that other processes and structures can be easily designed or modified based on the present disclosure to achieve the same purposes and / or the same advantages as the embodiments described herein. It should also be understood by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and various changes, substitutions, and modifications can be made without violating the spirit and scope of the present disclosure.

Claims

1. A printing method, characterized in that: include: acquiring at least one image of a substrate loaded in a printing system, determining an actual position of a first alignment feature on the substrate in a reference frame of the printing system based on the at least one image, determining expected positions of a plurality of second alignment features on the substrate based on the actual positions of the first alignment features, determining actual positions of the plurality of second alignment features in a reference frame of the printing system based on the at least one image and the expected positions of the second alignment features, determining target positions of a plurality of printing areas on the substrate based on the actual position of the second alignment feature, and Based on the target positions of the printing areas, the printing material is controlled to be ejected onto the substrate in the plurality of printing areas.

2. The printing method according to claim 1, wherein The at least one image includes a first image and a second image, and the method further includes: acquiring the first image of the first alignment feature on the substrate, wherein an actual position of the first alignment feature on the substrate is determined based on the first image; and Based on the expected position of the second alignment feature, a second image of the second alignment feature on the substrate is acquired, wherein the actual position of the second alignment feature is determined based on the second image.

3. The printing method according to claim 2, characterized in that During a first scan of the substrate from the input side of the printing system to the output side of the printing system, the first image is captured using a wide-angle camera; and during a second scan of the substrate from the output side of the printing system to the input side of the printing system, the second image is captured using multiple high-magnification cameras.

4. The printing method according to claim 3, characterized in that Also includes: The substrate is aligned between the first scan and the second scan.

5. The printing method according to claim 4, characterized in that Aligning the substrate includes aligning the substrate along two orthogonal directions.

6. The printing method according to claim 1, wherein: Also includes: A placement error of the substrate is determined, wherein determining target positions of the plurality of print areas includes compensating for the placement error.

7. The printing method according to claim 6, characterized in that The at least one image includes a first image and a second image, and the method further includes: acquiring the first image of the first alignment feature on the substrate, wherein an actual position of the first alignment feature on the substrate is determined based on the first image; and A second image of the second alignment feature on the substrate is acquired based on the expected position of the second alignment feature, wherein an actual position of the second alignment feature is determined based on the second image.

8. The printing method according to claim 7, characterized in that capturing the first image with a wide-angle camera during a first scan of the substrate from an input side of the printing system to an output side of the printing system; and capturing the second image with a plurality of high-magnification cameras during a second scan of the substrate from an output side of the printing system to an input side of the printing system; And the substrate is aligned between the first scan and the second scan.

9. The printing method according to claim 8, characterized in that The substrates are aligned along two orthogonal directions.

10. A printing method, characterized in that: include: Capturing a first image of a substrate loaded in the printing system with a first camera, determining an actual position of a first alignment feature on the substrate in a reference frame of the printing system based on the first image, Using a second camera to capture a second image of the substrate, determining an expected position of a second alignment feature on the substrate based on the actual position of the first alignment feature, determining an actual position of the second alignment feature in a reference frame of the printing system based on the second image and the expected position of the second alignment feature, determining a target position of a printing area on the substrate based on the actual position of the second alignment feature, and Based on the target position of the printing area, the printing material is controlled to be ejected onto the substrate in the printing area.

11. The printing method according to claim 10, characterized in that During a first scan of the substrate from the input side of the printing system to the output side of the printing system, the first image is captured using a wide-angle camera; and during a second scan of the substrate from the output side of the printing system to the input side of the printing system, the second image is captured using a high-magnification camera.

12. The printing method according to claim 11, characterized in that Also includes: The substrate is aligned between the first scan and the second scan.

13. The printing method according to claim 12, characterized in that Aligning the substrate includes aligning the substrate along two orthogonal directions.

14. The printing method according to claim 13, characterized in that Also includes: A placement error of the printed area is determined.

15. The printing method according to claim 14, characterized in that The placement error is an alignment error or a rotation error.

16. The printing method according to claim 15, characterized in that Also includes: The actual position of the edge of the printing area is determined.

17. The printing method according to claim 16, characterized in that Also includes: A relationship between the expected position and the actual position of the second alignment feature is determined.

18. A printing method, characterized in that: include: During the multiple scans of the substrate, a first camera is used to capture a plurality of first images of the substrate loaded in the printing system. determining actual positions of a plurality of first alignment features on the substrate in a reference frame of the printing system based on the first image, During the multiple scans, a second camera is used to capture a plurality of second images of the substrate. determining expected positions of a plurality of second alignment features on the substrate based on an actual position of at least one of the first alignment features, determining an actual position of the second alignment feature in a reference frame of the printing system based on the second image and the expected position of the second alignment feature, determining target positions of a plurality of printing areas on the substrate based on the actual position of the second alignment feature, and Based on the target position of the printing area, the printing material is controlled to be ejected onto the substrate in the printing area.

19. The printing method according to claim 18, characterized in that Also includes: During the plurality of scans, the substrate is aligned at least once along two orthogonal directions.

20. The printing method according to claim 18, wherein Also includes: Before starting the multiple scans, at least one of the first camera and the second camera is moved to a target position.

Images