Discharge control using an imaging device

Abstract

To provide a printing system for achieving high accuracy in positioning of dispensing nozzles and a print base material in an inkjet printer.SOLUTION: A printing system 200 includes a substrate support 102, a print head assembly 119 which is positioned facing the substrate support, and an imager 202. The print head assembly includes: a plurality of dispensing nozzles 206 extending in an ejection direction towards the substrate support; and a plurality of marks. The imager is movable relative to the print head assembly and oriented in a direction opposite to the ejection direction for capturing at least one image including the plurality of marks indicating positions of the plurality of dispensing nozzles in the print head assembly.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 62 / 775,955, filed December 6, 2018, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] FIELD Embodiments of the present application relate generally to inkjet printing systems. In particular, methods, systems, and / or apparatus for controlling jetting in inkjet printing systems are described.

[0003] Inkjet printing is commonly used in office and home printers, as well as industrial-scale printers used for display manufacturing, high-volume document printing, material deposition on manufactured articles such as printed circuit boards (PCBs), and construction of biological articles such as tissue. Many commercial and industrial inkjet printers, as well as some consumer printers, use piezoelectric dispensers to deposit the printing material onto the substrate. A piezoelectric element is positioned adjacent to a printing material reservoir, and when a voltage is applied to the piezoelectric element, the piezoelectric element deforms and applies a compressive force to the printing material reservoir. The printing material reservoir is configured to dispense the printing material when subjected to the compressive force.

[0004] Some inkjet printing applications require high precision in the positioning of the ejection nozzles and / or the print substrate. In view of this, methods, systems and / or apparatuses are proposed for controlling the ejection of printing material in an inkjet printer. Summary of the Invention

[0005] In one embodiment, a printing system includes a substrate support, a printhead assembly positioned opposite the substrate support, the printhead assembly including a plurality of ejection nozzles extending in an ejection direction toward the substrate support, and a plurality of marks, the imager being movable relative to the printhead assembly and oriented in a direction opposite the ejection direction to capture at least one image including a plurality of marks indicating positions of the plurality of ejection nozzles of the printhead assembly.

[0006] In one embodiment, a printing method includes: an imaging device capturing an image of at least one of a plurality of marks on a print head assembly; detecting the plurality of marks in the at least one image captured by the imaging device; determining positions of a plurality of discharge nozzles of the print head assembly based on the detected plurality of marks; and discharging printing material from the plurality of discharge nozzles onto the substrate based on the determined positions of the plurality of discharge nozzles while moving the substrate relative to the print head assembly.

[0007] In one embodiment, a printing system includes a substrate support, a printhead assembly disposed opposite the substrate support, a first imaging device, a second imaging device, and a controller. The printhead assembly includes a plurality of discharge nozzles extending in a discharge direction toward the substrate support and a plurality of first marks. The first imaging device is movable relative to the printhead assembly and oriented in a direction opposite to the discharge direction to capture at least one first image including the plurality of first marks indicating positions of the plurality of discharge nozzles of the printhead assembly. The second imaging device is movable relative to the substrate support and oriented toward the substrate support to capture at least one second image of a substrate on the substrate support. The controller is configured to control the discharge of printing material from the plurality of discharge nozzles onto the substrate based on the at least one first image and the at least one second image.

[0008] In one embodiment, a flat panel display is produced by a printing method that includes capturing an image of at least one of a plurality of marks on a printhead assembly with an imaging device. The plurality of marks are detected in the at least one image captured by the line-scan imaging device. Positions of a plurality of discharge nozzles of the printhead assembly are determined based on the detected plurality of marks. Printing material is ejected from the plurality of discharge nozzles onto the substrate based on the determined positions of the plurality of discharge nozzles while the substrate is moved relative to the printhead assembly. [Brief explanation of the drawings]

[0009] Aspects of the present disclosure will be best understood from the following detailed description when read in conjunction with the accompanying drawings, in which: In accordance with standard industry practice, the various features are not drawn to scale, and in fact the dimensions of the various features may be arbitrarily increased or decreased for illustrative purposes.

[0010] [Figure 1] FIG. 1 is a top isometric view of a printing system according to one embodiment.

[0011] [Figure 2A] FIG. 1 is a schematic side view of a printing system according to one embodiment, showing a printhead assembly in one position. [Figure 2B] FIG. 2 is a schematic side view of a printing system according to one embodiment, showing a printhead assembly in another position. [Figure 2C] FIG. 10 is a schematic top view of a printing system according to another embodiment.

[0012] [Figure 3A] FIG. 2 is a schematic plan view of an imaging device and printhead assembly according to one embodiment. [Figure 3B] FIG. 10 is a schematic plan view of an imaging device and printhead assembly according to another embodiment.

[0013] [Figure 4]1 is a flowchart of a printing method according to an embodiment.

[0014] [Figure 5A] FIG. 1 is a schematic side view of a printing system according to an embodiment.

[0015] [Figure 5B] FIG. 2 is a schematic plan view of an imaging device and a substrate according to an embodiment.

[0016] [Figure 6] 1 is a flowchart of a printing method according to an embodiment.

[0017] [Figure 7] FIG. 2 is a block diagram of a control unit according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] The following disclosure provides numerous embodiments or examples of various features of the present subject matter. Specific examples of components, values, operations, materials, arrangements, etc. are described below to facilitate understanding of the disclosure. It should be understood that these specific examples are merely illustrative and are not intended to be limiting. Other components, values, operations, materials, arrangements, etc. are also contemplated. For example, although reference numerals and / or characters may be repeated in various examples throughout this disclosure, this repetition is for the purposes of brevity and clarity and does not dictate a relationship between the various embodiments and / or configurations described herein. Furthermore, for convenience of description, spatially relative terms such as "below," "under," "lower," "above," and "upper" may be used herein to describe the relationship of one element or feature shown in each figure to another element or feature. These spatially relative terms are intended to encompass various orientations of the device during use or operation in addition to the orientation depicted. Devices may be oriented in other orientations (rotated 90 degrees or otherwise), and the spatially relative descriptions used herein may be interpreted accordingly.

[0019] Some inkjet printing applications require high precision in positioning of the discharge nozzles and / or the substrate to achieve the desired high-quality printed product. To accurately position the discharge nozzles, nozzle mapping is performed to map the positions of the discharge nozzles to corresponding positions in a reference frame of the inkjet printing system. The mapped positions of the discharge nozzles are used to perform accurate printing. The mapped positions of the discharge nozzles are obtained from image data acquired by a line-scan imaging device with a single vertical array of image sensors. Compared to other approaches that use an array of image sensors arranged in multiple rows and columns to acquire image data, the use of a line-scan imaging device significantly reduces the time and complexity required to acquire image data, resulting in a faster printing process.

[0020] FIG. 1 is a top isometric view of a printing system according to one embodiment.

[0021] The printing system 100 includes a substrate support 102, a printing assembly 104, and a holder assembly 106 for manipulating the substrate during printing. The printing system 100 is mounted on a base 108. In one embodiment, the base 108 is a large component to minimize vibration transmission to the moving parts of the printing system 100. In one example, the base 108 is a granite block. The substrate support 102 is disposed on the base 108 and includes a support surface 110 and a device for making the support surface 110 substantially frictionless. In one example, the support surface 110 is an air table that forms a gas cushion that suspends the substrate. The support surface 110 is characterized by a plurality of holes 112 through which gas is ejected to provide an upward force that maintains the substrate at a desired height above the support surface 110. Some of the holes are also controllably configured to suction gas from the gas cushion that suspends the substrate, allowing for precise localized control of the substrate height.

[0022] The printing assembly 104 includes a dispensing assembly 114 mounted on a printing support 116. The printing support 116 is mounted relative to the substrate support 102, providing structural access for the dispensing assembly 114 to precisely apply printing material to a substrate on the substrate support 102. The printing support 116 includes a rail or beam 117 that traverses the substrate support 102, thereby enabling the dispensing assembly 114 to traverse the substrate support 102 and deposit printing material anywhere on the substrate between one side of the printing support 116 and the other. In one embodiment, the printing support 116 is attached to and extends from a base 108 to provide stable support for the dispensing assembly 114. On either side of the substrate support 102, two stands 120 extend from the base 108 to the rails 117. The rails 117 extend across the substrate support 102. In one embodiment, both the stand 120 and the rail 117 are made of the same material as the base 108. In one example, the stand 120, rail 117, and base 108 are integrally formed from a single block of granite.

[0023] The ejection assembly 114 includes at least one printhead assembly 119 and a print assembly controller 118. The print assembly controller 118 includes electronics and / or sensors that control the printhead assembly 119's functional parameters, such as its position along the print support 116, timing, duration, type of printing material, and ejection profile. The printhead assembly 119 is movable along a rail 117 on the print support 116 by movement of a print carriage 122. The print carriage 122 is coupled to the print support 116 and translates the printhead assembly 119 along the rail 117 from one end of the rail 117 to the other. In one example, the print carriage 122 is driven by a motor or servo motor. For simplicity, power and signal lines are not shown.

[0024] A substrate (not shown in FIG. 1 ) is positioned below the printing assembly 104 by a holder assembly 106. The holder assembly 106 ensures that the substrate is in contact with the holder assembly 106 when the substrate is placed on the printing assembly 104 and moves the substrate along the substrate support 102 to position the substrate relative to the printing assembly 104 so that the printing material is accurately dispensed onto the substrate. 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. The first direction is indicated by arrow 124 in FIG. 1 . The first direction 124 is referred to as the "Y direction" or "scan direction." The print head assembly 119 moves in a second direction generally perpendicular to the first direction, guided by rails 117. The rails 117 extend generally in the second direction indicated by arrow 126 in FIG. 1 . The second direction 126 is referred to as the "X-direction" or "cross-scan direction," and the rail 117 is referred to as the "X-beam." A third direction, generally perpendicular to the first and second directions, is indicated by arrow 125 in FIG. 1. The third direction 125 is referred to as the "Z-direction." The X, Y, and Z directions are the axial directions of a coordinate system, indicated by arrows 124, 125, and 126, that serves as a frame of reference for the printing system 100. In at least one embodiment, the origin of this coordinate system is a fixed point, for example, based on the base 108.

[0025] The holder assembly 106 is disposed on a holder assembly support 128, which in one embodiment is a rail extending in a first direction along an edge 130 of the substrate support 102 for substantially the entire length thereof. In one embodiment, the holder assembly support 128 is attached to the base 108 and provides stable support for the holder assembly 106. In one embodiment, the holder assembly support 128 is made of the same material as the base 108. In one example, the holder assembly support 128, base 108, and print support 116 are integrally formed from a single block of granite. The holder assembly support 128 is referred to as a "Y-beam." During operation, the holder assembly 106 moves along the holder assembly support 128 to position the securely held substrate at any desired location on the substrate support 102. The print assembly 104, for example, by operation of the print assembly control 118, positions the print head assembly 119 to enable precise access to the location on the substrate where printing material is to be dispensed.

[0026] The system controller 129 receives signals from various sensors located throughout the printing system 100 and sends signals to each component of the printing system 100 to control printing. The system controller 129 is operably coupled to the print assembly controller 118 and the holder assembly controller 131, for example, via a network. The holder assembly controller 131 controls the operation of the holder assembly 106. One or more of the substrate support 102, print assembly 104, holder assembly 106, and other auxiliary systems, such as an environmental control system or a material management system, have sensors operably coupled to the system controller 129 that send signals to the system controller 129 regarding the status of each component during printing operations. The system controller 129 contains data and instructions for determining the control signals to send to each component of the printing system 100 that it controls. In one embodiment, two or more of the system controller 129, print assembly controller 118, and holder assembly controller 131 are integrated into a single controller. In one embodiment, at least one of system controller 129, print assembly controller 118, and holder assembly controller 131 is implemented as multiple controllers distributed within printing system 100 and connected to one another via a network. An example configuration of a controller according to one embodiment is described with reference to FIG. 7. For simplicity, in the following description, "controller" refers to any one or more of the controllers of printing system 100.

[0027] To achieve precision in inkjet printing, tiny droplets of printing material are deposited onto correspondingly small areas on the substrate. For example, droplets of printing material with diameters of 10-30 μm are deposited onto areas of the substrate measuring 25-200 μm. This deposition is often performed while the substrate is moving in the Y direction (scan direction) to minimize printing time. Such precision printing is complicated by many factors, including minute imperfections in the dimensions and / or position of components of the printing system 100, variations in these dimensions with temperature, imperfections in the substrate such as misalignment of structures already formed on the substrate, variations in the translational speed of the substrate, the discharging assembly 114, and the holder assembly 106, and variations in the distance from the printhead assembly 119 to the substrate. For example, if the position of the discharge nozzles of the printhead assembly 119 is not precisely known or controlled within the reference frame of the printing system 100, it can be difficult to control the droplets of printing material from the discharge nozzles of the printhead assembly 119 to reach their target locations even when the substrate is in the proper position. In this regard, nozzle mapping is performed to know or control the position of the ejection nozzles within the frame of reference of the printing system 100. In another regard, features of the substrate are mapped into the frame of reference of the printing system 100 so as to correct for any misalignment of the substrate.

[0028] 2A and 2B are schematic side views of a printing system 200 according to one embodiment, showing a printhead assembly in various positions. In one embodiment, printing system 200 includes one or more features of printing system 100 described herein.

[0029] As shown in FIGS. 2A and 2B , printing system 200 includes substrate support 102 and imaging device 202, with printhead assembly 119 positioned opposite substrate support 102. Herein, imaging device 202 is a line-scan imaging device, although other imaging devices may be used. Printhead assembly 119 includes a plurality of ejection nozzles 206 extending in an ejection direction 225 toward substrate support 102. Printhead assembly 119 includes a plurality of marks (also referred to as “housing marks”), as described herein with respect to FIGS. 3A and 3B . Line-scan imaging device 202 is movable relative to printhead assembly 119. For example, FIGS. 2A and 2B illustrate different relative positions of line-scan imaging device 202 and printhead assembly 119. In this example, printhead assembly 119 is coupled to rail 117 by an air-bearing assembly or other low-friction coupling means (not shown). A linear actuator coupled between the printhead assembly 119 and one or both of the stand 120 moves the printhead assembly 119 in the cross-scan direction. The line-scan imager 202 is oriented opposite the jetting direction 225 and captures at least one image including a plurality of marks to determine the positions of the printhead assembly's jetting nozzles 206. In the example configuration of Figures 2A and 2B, the jetting direction 225 is opposite the Z direction, and the line-scan imager 202 is oriented in the Z direction opposite the jetting direction 225.

[0030] In one embodiment, the line scan imaging device 202 is stationary relative to the substrate support 102. For example, in this example, the line scan imaging device 202 is fixed to stand 120A of two stands 120A and 120B similar to stand 120 of printing system 100. Stands 120A and 120B extend from base 108 on either side of the substrate support 102. The printhead assembly 119 is movable in the cross-scan direction (X direction) relative to the line scan imaging device 202 and the substrate support 102. For example, it is movable from a center position on rail 117 shown in FIG. 2A to a position adjacent to stand 120A and facing the line scan imaging device 202, as shown in FIG. 2B. While the printhead assembly 119 passes by the line scan imaging device 202 near the position shown in FIG. 2B, the printhead assembly 119 can be positioned within the imaging field of view of the line scan imaging device 202. The line scan imager 202 captures an image of at least one of the opposing discharge nozzles 206. The captured image is transferred to a controller 118 coupled to the line scan imager 202 or another controller of the printing system 100, as shown in Figures 2A and 2B.

[0031] The above-described arrangement of the line scan imaging device 202 is an example configuration, and other configurations are within the scope of various embodiments. In one example, another imaging device 204 (also a line scan imaging device in this example) is fixed to the stand 120B on the opposite side of the substrate support 102, and the print head assembly 119 can be moved to either side of the substrate support 102 to image the discharge nozzles 206. In one embodiment, the line scan imaging device 204 is omitted, or two or more line scan imaging devices are included in the printing system 200. As another example, in at least one embodiment, the line scan imaging device 202 or the line scan imaging device 204 is movable relative to the substrate support 102, e.g., by a motor, and the imaging device is positioned at a predetermined image capture position, such as the position shown in FIG. 2B, to capture an image of the discharge nozzles 206. For example, as shown in FIG. 2B, after capturing an image, the line scan imaging device 204 moves away from the image capture position, e.g., by retracting as shown by arrow 251 or swinging as shown by arrow 252, so as not to interfere with the printing process. 2B , rather than moving print head assembly 119 over stationary line scan imager 202 to acquire an image, line scan imager 202 is physically moved relative to print head assembly 119, or both line scan imager 202 and print head assembly 119 are physically moved relative to each other to acquire an image. For example, line scan imager 202 can be coupled to rail 117 by a linear positioner, and line scan imager 202 can be moved relative to print head assembly 119 to a position opposite print head assembly 119 to acquire an image of discharge nozzles 206.

[0032] FIG. 2C is a schematic top view of a printing system 200 according to another embodiment. For simplicity, FIG. 2C omits some components, such as the substrate support 102 and the base 108. In the exemplary configuration of FIG. 2C , the line-scan imaging device 202 and / or the line-scan imaging device 204 can be moved along the Y direction, e.g., by a motor, to scan the discharge nozzles 206 and acquire images thereof. For example, the line-scan imaging device 202 is coupled to a rail 274 via a motorized carriage (not shown in FIG. 2C ). The rail 274 is supported along the inner edge of the stand 120A. The rail 274 is attached to the stand 120A by a connecting member 272. The line-scan imaging device 202 can be moved linearly along the rail 274 between positions 202A and 202B, as indicated by arrow 276. As another example, the line-scan imaging device 204 is coupled to a pivot 284 via a swivel mount 282. Pivot 284 is supported by stand 120B. Line scan imager 204 is pivotable about pivot 284 between positions 204A and 204B, as indicated by arrow 286. When multiple cameras are used, each camera may be coupled to printing system 200 in any of the ways described above, with various types of couplings being used depending on the camera.

[0033] Figure 3A is a schematic plan view of a line scan imaging device 202 and printhead assembly 119 according to one embodiment. Figure 3A is a combined top plan view of line scan imaging device 202 (looking down in the discharge direction 225 of Figure 2A) and a bottom plan view of printhead assembly 119 (looking up in the Z direction of Figure 2A) side by side. A nozzle face 321 of a housing or body 330 of printhead assembly 119 is shown. The discharge ends of each discharge nozzle 206 are disposed in nozzle face 321.

[0034] The line scan imaging device 202 includes multiple image sensors 332. In one embodiment shown in FIGS. 3A and 3B, all of the image sensors 332 of the line scan imaging device 202 are arranged in a single vertical row (e.g., line 331) along the scan direction (Y direction). In another embodiment (not shown), the image sensors 332 of the line scan imaging device 202 are arranged in two or more vertical rows. For example, the image sensors 332 in the first row are configured as primary image sensors that acquire image data for nozzle mapping, and the image sensors 332 in the second row are configured as redundant or secondary sensors that provide image data in the event that one or more of the primary image sensors fail. The image sensors 332 are photosensitive elements that capture light reflected from the nozzle face 321 of the printhead assembly 119 toward the line scan imaging device 202 and record electrical signals responsive to the captured light. The image sensors 332 capture images of the printhead assembly 119 while the printhead assembly 119 moves relative to the line scan imaging device 202 in the cross-scan direction (X direction). In this respect, image capture by line scan imager 202 is similar to image capture performed by copiers and scanners using similar linear photosensor configurations. To capture images with feature dimensions in the range of a few microns, e.g., 5-10 microns, image sensor 332 is configured to provide a high resolution, e.g., approximately 0.1 microns. Examples of image sensors include, but are not limited to, complementary metal-oxide semiconductor (CMOS) sensors and charge-coupled device (CCD) sensors.

[0035] In one embodiment, ambient light provides illumination for image capture by the line scan imager 202. However, in at least one embodiment, depending on the optical characteristics of the environment in which the line scan imager 202 operates, at least one light source (not shown) is provided to illuminate the nozzle face 321 of the print head assembly 119 during image capture. Various parameters of the light emitted by the light source, such as the wavelength, intensity, wave motion, and / or angle of incidence, are selected and / or varied depending on one or more considerations, including, but not limited to, the reflectivity of the nozzle face 321, the color and / or other optical characteristics of the discharge nozzles 206 and the marks on the nozzle face 321, and the ambient atmosphere (e.g., an inert environment) of the line scan imager 202. In one embodiment, visible light is used to illuminate the nozzle face 321 of the print head assembly 119 during image capture, while other embodiments use non-visible light (i.e., electromagnetic radiation outside the visible spectrum). The light source may be incorporated into the line scan imager 202 as, for example, a white LED light source, and is provided on a sensor face of the line scan imager 202 opposite the nozzle face 321 of the printhead assembly 119 .

[0036] The ejection nozzles 206 are visible in the nozzle face 321 of the printhead assembly 119. In the example configuration of FIGS. 3A and 3B, the ejection nozzles 206 are arranged in one or more rows extending in the X direction. For example, FIGS. 3A and 3B show four rows of ejection nozzles 206 corresponding to four printheads 320, 322, 324, and 326. The number of rows of ejection nozzles 206 and / or the number of ejection nozzles 206 within each row of the printhead assembly 119 shown in FIG. 3A is exemplary and will vary from printing system to printing system and / or printhead assembly to printing system. Some printhead assemblies do not have the ejection nozzles arranged in a particular pattern. In high-precision printing systems, each printhead assembly may have thousands of ejection nozzles. In one embodiment, as can be seen in FIG. 3A, the line 331 of the image sensor 332 of the line-scan imager 202 extends in the Y direction long enough to completely span all of the rows of ejection nozzles 206 of the printhead assembly 119. Alternatively, for a printhead assembly in which the ejection nozzles are not arranged in a particular pattern, the single line 331 of the image sensor 332 of the line scan imager 202 extends long enough to completely span the entire width (Y direction) of the area of ​​the nozzle face in which all of the ejection nozzles are located. Thus, in this configuration, a single pass of the printhead assembly 119 past the line scan imager 202 in the X direction can be used to capture an image that includes or encompasses all of the ejection nozzles 206 of the printhead assembly 119.

[0037] However, if the length of line 331 is not long enough to include all of the ejection nozzles 206 in a single pass (i.e., the line scan camera is shorter than the width of the nozzle face 321, as shown in FIG. 2C ), multiple line scan imagers 202 / 204 can be used and / or at least one line scan imager 202 / 204 can make multiple passes to acquire multiple images, each including a corresponding portion of the nozzle face 321. For example, using the configuration described with respect to FIG. 2C , the line scan imager 202 / 204 can be moved to subsequent positions to acquire images of each portion of the nozzle face 321. Alternatively, two or more cameras 202 can be positioned along the Y direction in FIG. 2C to scan the entire nozzle face 321 in a single pass. These multiple images can then be stitched together, for example by controller 118, to form a larger image that includes all of the ejection nozzles 206 of the printhead assembly 119, and this image can be used for nozzle mapping.

[0038] In general, the line scan imaging device 202 (or 204) typically includes multiple image sensors arranged in a vertical row along a first direction, with the line scan imaging device and the nozzle face 321 moving relative to each other in a second direction perpendicular to the first direction. Thus, the image sensor array scans the entire nozzle face 321. If the scan area on the nozzle face 321 has a dimension in the first direction that is longer than the length of the line scan imaging device in the first direction, the vertical row of line scan imaging devices must reposition the nozzle face 321 after one scan so that the area not reached in the first scan can be scanned in the second scan, increasing the time it takes to complete the scan. In such cases, two or more line scan imaging devices can be used to simultaneously scan an area larger than the range that a single line scan imaging device can access in a single scan. The two or more line scan imaging devices may be adjacent or non-adjacent, and the images acquired by the two or more line scan imaging devices may be combined into a composite image for processing, or may be processed individually. For example, when imaging one or more marks on the nozzle face 321, if the one or more marks are located over an area that cannot be imaged in a single scan by a single line-scan imaging device, two or more line-scan imaging devices can be used to image a mark area, or a portion thereof, that is larger than the field of view of a single line-scan imaging device. Multiple adjacent portions of the mark area can be imaged by multiple line-scan imaging devices, and the images can be combined to create a composite image of the entire mark area. Alternatively, two or more line-scan imaging devices can be used to image portions of the mark area that are too far away for a single line-scan imaging device to access in a single scan. Furthermore, when imaging an ejection nozzle, if the imaging area is larger than the field of view of a single line-scan imaging device, two or more line-scan imaging devices can be used, as described above.

[0039] In the exemplary configuration of Figure 3A, the multiple printheads include four horizontal rows of ejection nozzles 206, each row belonging to a printhead 320, 322, 324, or 326. Each of the printheads 320, 322, 324, or 326 is implemented as a cartridge or card removably disposed in a corresponding slot or area within a central region 327 of the nozzle face 321 of the printhead assembly 119. When installed in a corresponding slot or area within the central region 327, the printheads 320, 322, 324, or 326 are coupled to receive printing material and control signals. In response to the control signals, the ejection nozzles 206 of the printheads 320, 322, 324, or 326 eject printing material onto a substrate supported on the substrate support 102. In one embodiment, the printheads 320, 322, 324, or 326 include piezoelectric elements or transducers (not shown) associated with the ejection nozzles 206. Upon receiving a control signal, the piezoelectric element or transducer deforms, causing the corresponding discharge nozzle 206 to discharge printing material onto the substrate. Other configurations (e.g., other types of transducers and / or arrangements of discharge nozzles) may also be used. The print heads 320, 322, 324, 326 may be removed from the print head assembly 119 for inspection, maintenance, and / or replacement, and then reinstalled in the print head assembly 119. Repeated installation and removal of the print heads 320, 322, 324, 326, and the resulting mechanical failures and / or improper installation, may change the position or orientation of the discharge nozzles 206 of the print head assembly 119, potentially resulting in misalignment between the discharge nozzles and the intended print area on the substrate and resulting in defective prints. To address this issue, the nozzle locations may be mapped using the methods and apparatus described herein.

[0040] To perform nozzle mapping on or within the nozzle face 321 of the housing or body 330, the printhead assembly 119 has multiple housing marks—four housing marks 310, 312, 314, and 316 in this example—for determining the locations of the ejection nozzles 206 of the printhead assembly 119. In the example configuration of FIG. 3A , the housing marks 310, 312, 314, and 316 are positioned around a central region 327 where the ejection nozzles 206 are located. However, the housing marks 310, 312, 314, and 316 may be positioned at other locations on or within the nozzle face 321 and / or at other relative locations relative to the ejection nozzles 206. In one embodiment, the housing marks 310, 312, 314, and 316 are referred to as “fiducial marks.” These marks have one or more known characteristics, such as pattern, orientation, size, and location on the nozzle face 321 of the printhead assembly 119. The housing marks 310, 312, 314, and 316 may be attached (e.g., with an adhesive), etched or machined, or printed or painted onto the nozzle face 321 of the printhead assembly 119. Other methods for providing fiducial marks on the printhead assembly may also be used. The number and / or shape of the housing marks 310, 312, 314, and 316 in the example configuration of FIG. 3A are exemplary. The housing marks 310, 312, 314, and 316 can be of any number, shape, material, and / or orientation. By way of example, any of the housing marks 310, 312, 314, and 316 may include text, a barcode, a company name, and / or a logo. The greater the number of fiducial marks and / or the more complex the shapes of the marks, the greater the accuracy of the position of the ejection nozzles 206 determined using the housing marks 310, 312, 314, and 316.

[0041] To determine the location of the discharge nozzles 206 of the printhead assembly 119 using the housing marks 310, 312, 314, and 316, the controller 118 controls the line scan imaging device 202 to acquire an image of the nozzle face 321 of the printhead assembly 119 while the printhead assembly 119 passes by the line scan imaging device 202. The acquired image is transmitted from the line scan imaging device 202 to the controller 118, which detects the housing marks 310, 312, 314, and 316 and the at least one discharge nozzle 206 from the acquired image. Image processing algorithms and / or software and / or programs for recognizing objects based on known characteristics, such as pattern, position, size, and / or orientation, are well known in the art of image processing and will not be described in detail herein. In one embodiment, the controller 118 relies on such well-known algorithms and / or software and / or programs to recognize the housing marks 310, 312, 314, and 316 and the at least one discharge nozzle 206 from the acquired image.

[0042] In at least one embodiment, the controller 118 uses known characteristics of the housing marks 310, 312, 314, 316 (e.g., one or more of the pattern, orientation, size, and location), the known shape (e.g., circularity) and size of each discharge nozzle 206, and the expected location of each discharge nozzle 206 relative to the housing marks 310, 312, 314, 316. For example, the known characteristics of the housing marks 310, 312, 314, 316 are included in printhead assembly configuration data stored in and / or accessible to the controller 118. The printhead assembly configuration data may further include other data related to the discharge nozzles 206, including, but not limited to, at least one of: the number of rows of discharge nozzles, the number of discharge nozzles per row, the spacing between adjacent discharge nozzles within a row or column of discharge nozzles, the spacing between adjacent rows and / or columns, the spatial relationship of each row of discharge nozzles to the housing marks, etc. In one embodiment, the printhead assembly configuration data is a coordinate map representing the housing marks and discharge nozzles, e.g., a series of x-y locations on or within the housing marks and discharge nozzles. From the printhead assembly configuration data, the controller 118 can determine the expected position of each discharge nozzle 206 relative to the housing marks 310, 312, 314, and 316. Once the controller 118 recognizes the housing marks 310, 312, 314, and 316 and at least one discharge nozzle 206 from the acquired image, it compares their recognized positions from the acquired image with known / expected positions from the printhead assembly configuration data. From this comparison, the controller 118 derives a relationship that transforms the recognized positions from the acquired image to the known / expected positions from the printhead assembly configuration data. The controller 118 uses the derived relationship and the predicted positions of all of the other discharge nozzles 206 to interpolate the positions of all of the other discharge nozzles 206 of the print head assembly 119 using bilinear interpolation, which may include one or more interpolation operations such as translation, rotation, skew, scaling, etc. As a result, the positions of all of the discharge nozzles 206 of the print head assembly 119 are determined.

[0043] The controller 118 then maps the determined positions for all of the discharge nozzles 206 of the print head assembly 119 to corresponding positions in the printing system's frame of reference (e.g., a coordinate system having axes in the X, Y, and Z directions as described herein). This mapping is possible because the print head assembly 119 has at least one known position in the printing system's frame of reference under the control of the controller 118. In one embodiment, the mapping of the determined positions for all of the discharge nozzles 206 to corresponding positions in the printing system's frame of reference uses bilinear interpolation, which includes one or more interpolation operations such as translation, rotation, shear, and scaling.

[0044] The controller 118 controls the dispensing of printing material from the discharge nozzle 206 onto the substrate supported by the substrate support 102 based on the mapped position of the discharge nozzle 206 within the reference frame of the printing system. The mapped position of the discharge nozzle 206 accurately reflects the actual detected position of the discharge nozzle 206, thereby improving printing accuracy.

[0045] 3B is a schematic plan view of line-scan imager 202 and printhead assembly 319 according to one embodiment. In one embodiment, printhead assembly 319 includes one or more features of printhead assembly 119 described herein. FIG. 3B shows a top plan view of line-scan imager 202 (looking down in ejection direction 225 in FIG. 2A ) and a bottom plan view of printhead assembly 319 (looking up in the Z direction in FIG. 2A ).

[0046] Compared to printhead assembly 119, printhead assembly 319 further includes multiple printhead marks at predetermined (or known) positions relative to the discharge nozzles 206. As with housing marks 310, 312, 314, and 316, the printhead marks can be of any number and / or shape and / or material and / or orientation. For example, printhead 320 includes printhead marks 340 and 342 at predetermined positions relative to the discharge nozzles 206 of printhead 320. The other printheads 322, 324, and 326 also include similar printhead marks at predetermined positions relative to the discharge nozzles 206 of printheads 322, 324, and 326, respectively. The following description of printhead 320 also applies to the other printheads 322, 324, and 326.

[0047] In at least one embodiment, printhead marks 340, 342 are formed on or in the underside of printhead 320 such that they have a predetermined positional relationship to discharge nozzles 206 of printhead 320. Similar to the description of FIG. 3A , controller 118 controls line scan imaging device 202 to acquire images of nozzle face 321 of printhead assembly 319 while printhead assembly 319 passes line scan imaging device 202. The acquired images are transmitted from line scan imaging device 202 to controller 118, which detects housing marks 310, 312, 314, 316 and printhead marks 340, 342 from the acquired images. Printhead assembly configuration data allows controller 118 to determine the expected positions of printhead marks 340, 342 relative to housing marks 310, 312, 314, 316. After recognizing the housing marks 310, 312, 314, and 316 and the printhead marks 340 and 342, the controller 118 derives a relationship that converts the positions and orientations recognized from the acquired image to the known / expected positions and orientations from the printhead assembly configuration data. Using the derived relationship and the expected positions and orientations of the printhead marks 340 and 342, the controller 118 interpolates the positions and orientations of those marks on the printhead assembly 319 and then interpolates the positions of the discharge nozzles 206 of the printheads 320 of the printhead assembly 319. The above process is also applicable to the other printheads 322, 324, and 326. As a result, the positions of all discharge nozzles 206 of the printhead assembly 319 are accurately determined. The controller 118 then performs nozzle mapping and print material discharge control based on the determined positions of the discharge nozzles 206, as described with reference to FIG. 3A .

[0048] In at least one embodiment, because the printhead marks 340, 342 are fixed to the printhead 320, inserting or removing the printhead 320 into or from the printhead assembly 319 does not affect the relative positions of the printhead marks 340, 342 and the ejection nozzles 206 of the printhead 320. Therefore, rather than directly detecting at least one ejection nozzle 206 as in the printhead assembly 119 described with reference to FIG. 3A , the positions of the ejection nozzles 206 of the printhead 320 can be determined by detecting the printhead marks 340, 342. In one embodiment, the printhead marks 340, 342 are larger and have a more distinctive (i.e., more recognizable) shape than the densely packed, small, circular ejection nozzles 206 (several microns in diameter). As a result, it is easier for the controller 118 to detect the printhead marks 340, 342 than to detect the ejection nozzles 206, thereby improving the speed and / or accuracy of the nozzle mapping process. This effect is particularly noticeable in inkjet printing applications, where thousands of small, closely spaced ejection nozzles are arranged within a printhead assembly. In such a printhead assembly, it can be difficult to identify one or more of the ejection nozzles in an acquired image, especially if the ejection nozzles are obscured by printing material from a previous printing operation. In one embodiment, a cleaning mechanism (not shown) is provided to clean the ejection nozzles before image acquisition, but it is still advantageous to provide printhead marks in a predetermined positional relationship to the ejection nozzles for nozzle mapping.

[0049] 4 is a flowchart of a printing method 400 according to one embodiment. The printing method 400 may be implemented in the printing system 200 by or under the control of at least one controller, as described herein. In the following description, the printing method 400 is implemented by or under the control of the controller 118.

[0050] In operation 405, the controller causes the imaging device to capture an image of at least one of the plurality of marks on the print head assembly. For example, as described with respect to FIG. 2B , the controller 118 moves the print head assembly 119 past the line scan imaging device 202 near the image capture location. The controller 118 also causes the line scan imaging device 202 to capture an image of the nozzle face 321 of the print head assembly 119 while the print head assembly 119 passes the line scan imaging device 202. The captured image includes at least the plurality of marks 310, 312, 314, 316 on the print head assembly 119.

[0051] In operation 415, the controller detects the plurality of marks in at least one image acquired by the imaging device. For example, the controller 118 uses one or more well-known image processing algorithms and / or software and / or programs described herein to detect or recognize the plurality of marks 310, 312, 314, 316 in the image acquired by the line-scan imaging device 202.

[0052] In operation 425, the controller detects the positions of the multiple discharge nozzles of the printhead assembly based on the detected multiple marks. In one example, the controller 118 detects or recognizes at least one discharge nozzle 206 and uses the detected positions of the at least one discharge nozzle 206 and housing marks 310, 312, 314, and 316 to determine the positions of all other discharge nozzles 206 of the printhead assembly 119, as described with reference to FIG. 3A. In another example, the controller 118 detects or recognizes printhead marks 340 and 342 at predetermined positions relative to the discharge nozzles 206 of the printhead 320 and uses the detected positions of the housing marks 310, 312, 314, and 316 and printhead marks 340 and 342 to determine the positions of all discharge nozzles 206 of the printhead assembly 319, as described with reference to FIG. 3B. Thus, although it is not possible or practical to directly image and recognize all of the ejection nozzles of a printhead assembly, the locations of all of the ejection nozzles in the printhead assembly can be determined by imaging and recognizing either the printhead assembly housing mark or the nozzles or printhead marks associated with the ejection nozzles.

[0053] In operation 435, the controller controls the ejection of printing material from the plurality of ejection nozzles onto the substrate based on the detected positions of the plurality of ejection nozzles. For example, the controller 118 maps the determined positions of the ejection nozzles 206 of the printhead assembly 119 or 319 to corresponding positions in the printing system's frame of reference based on the known positions of the printhead assemblies within the printing system's frame of reference, as described herein. The controller 118 then uses the mapped positions of the ejection nozzles 206 within the printing system's frame of reference to control when the ejection nozzles eject printing material and / or which ejection nozzles to use according to print data or a recipe that includes coordinates within the printing system's frame of reference. This results in a printed product with high printing accuracy. For example, if a print nozzle is found to be located a distance d away from its expected position, a droplet ejected according to an existing printing plan will arrive at a position that is a distance d away from its target position t. The distance d is multiplied by the x-component d. x If there is a printhead assembly -d x The average distance (avg_d) that the print nozzles are away from their expected positions in the x direction can be adjusted to compensate. x ), print assembly is off by -(avg_d x ) can be adjusted and corrected. y If there is d y The print plan can be adjusted globally using a jetting delay of / v, where v is the translational velocity of the substrate in the y direction. y ) and the y component of

[0054] In one embodiment, printed products produced using the above-described printing methods include, but are not limited to, solar panels, flat panel displays such as organic light emitting diode (OLED) displays, and the like.

[0055] In one embodiment, the nozzle mapping described herein is performed during initialization of the printing system and / or between printing operations. In at least one embodiment, the nozzle mapping described herein is performed during printing operations. For example, the print head assembly 119 is moved from the printing position shown in FIG. 2A to the image acquisition position for image acquisition and nozzle mapping described with respect to FIG. 2B, and then the print head assembly 119 is returned to the printing position to continue printing operations based on the results of the nozzle mapping.

[0056] In one embodiment, a line scan imager is used that has a single vertical row of photosensors at least as long as the extent of the ejection nozzles of the printhead assembly, so that a single pass of the printhead assembly through the line scan imager can provide a high-resolution image that includes all of the ejection nozzles, reducing printer initialization time and / or print interruptions.

[0057] In one embodiment, a line-scan imaging device significantly reduces the time and complexity of image data acquisition compared to other approaches that use an array of image sensors arranged in multiple columns and rows to acquire image data, thereby speeding up nozzle mapping, printer initialization, and / or the printing process. In some circumstances, a conventional camera with an array of photosensors may take 15-20 minutes to acquire an image of sufficient quality for nozzle mapping, whereas in the same circumstances, a line-scan imaging device according to one embodiment may only take a few minutes to acquire a high-resolution image suitable for nozzle mapping. This is because, to acquire an acceptable image of thousands of densely packed ejection nozzles with a conventional camera, the camera must be properly aligned with the printhead assembly, which can be time-consuming. While such imaging devices can be used in the methods and apparatus described herein, using a line-scan imaging device for image acquisition often eliminates the need for camera alignment; instead, a single pass of the printhead assembly through the line-scan imaging device is sufficient to acquire high-quality, high-resolution images. As mentioned above, even when several passes are required to image the entire nozzle face, the imaging speed is still improved over other approaches that use conventional cameras. This increases the imaging speed, which not only improves throughput but also allows for shorter intervals between measurements. As a result, measurements and / or corrections can be made more frequently during a printing operation, resulting in increased printing accuracy.

[0058] 5A is a schematic side view of one embodiment of a printing system 500. In one embodiment, printing system 500 includes one or more features of printing system 100 and / or printing system 200 described herein.

[0059] Compared to printing system 200, printing system 500 further includes a second imaging device 502 that is movable relative to the substrate support 102 and oriented toward the substrate support 102 to capture at least one second image of a substrate 508 on the substrate support 102. In one example, the substrate 508 is a glass substrate. Other substrate materials are within the scope of various embodiments. In the example configuration of FIG. 5A , the imaging device 502 is mounted to the print carriage 122 so as to be movable with the print head assembly 119 relative to the substrate 508. In another example configuration (not shown), the imaging device 502 is movable independently of the print head assembly 119 (e.g., via a drive shaft or motor). For example, the imaging device 502 may have an independently actuable actuation connection to the rail 117.

[0060] Figure 5B is a schematic plan view of an embodiment of an imaging device 502 and a substrate 508. Figure 5B shows a top plan view of the substrate 508 (looking down in the discharge direction 225 of Figure 5A) and a bottom plan view of the imaging device 502 (looking up in the Z direction of Figure 5A).

[0061] The substrate 508 includes at least one print area where droplets of printing material ejected from the ejection nozzles land. This area is then processed to become a permanent part of the printed product. In the example configuration of FIG. 5B , the substrate 508 includes seven print areas sp1 through sp7, each corresponding to a display panel to be manufactured. To identify the location of the print area, the substrate 508 includes multiple board marks for each print area. In the example configuration of FIG. 5B , each print area includes four board marks at the corners. For simplicity, FIG. 5B only shows board marks 510, 512, 514, and 516 for identifying print area sp1 and board marks 520, 522, 524, and 526 for identifying print area sp3. In one embodiment, the board marks are referred to as "fiducial marks" and have one or more known characteristics, such as pattern, orientation, size, and location on the printed circuit board 508. The board marks are attached (e.g., by adhesive), etched or machined, or printed or painted onto the substrate 508. Other methods can also be used to provide the substrate marks on the substrate. The number and / or shape of the substrate marks in the configuration example of FIG. 5B are exemplary. The substrate marks can be of any number, shape, material, and / or orientation. Any of the substrate marks can include text, barcodes, company names, logos, etc. The greater the number of substrate marks and / or the more complex the shapes of the marks, the more accurate the position of the printing area determined using the substrate marks.

[0062] To determine the position of the print region sp1 using the board marks 510, 512, 514, and 516, the controller 118 controls the imaging device 502 to capture at least one image of the substrate 508 while the substrate 508 passes underneath the imaging device 502, for example in the Y direction. The one or more captured images are transmitted from the imaging device 502 (which may be a line scan imaging device) to the controller 118, which detects the board marks 510, 512, 514, and 516 from the one or more captured images. In one example, the board marks 510, 512, 514, and 516 are all captured in a single image. In another example, the board marks 510 and 512 are captured in a single image, and the other board marks 514 and 516 are captured in a separate image. In yet another example, the board marks 510, 512, 514, and 516 are each captured in a separate image. Image processing algorithms and / or software and / or programs for recognizing objects based on known characteristics such as pattern, position, size, and / or orientation are well known in the art of image processing and will not be described in detail herein. In one embodiment, the controller 118 relies on such well-known algorithms and / or software and / or programs to recognize the substrate marks 510, 512, 514, 516 from one or more acquired images, similar to the method for recognizing the housing marks 310, 312, 314, 316 described with respect to Figures 3A and 3B.

[0063] The controller 118 then maps the positions of the print area sp1 indicated by the detected substrate marks 510, 512, 514, and 516 to corresponding positions in the printing system's frame of reference, similar to the method for mapping the determined positions of the discharge nozzles 206 to corresponding positions in the printing system's frame of reference described with reference to Figures 3A and 3B. Note that different mapping algorithms may be used to map different marks or sets of marks. For example, the housing marks 310, 312, 314, and 316 may be mapped using a first algorithm, and the substrate marks 510, 512, 514, and 516 may be mapped using a second algorithm that is different from the first algorithm.

[0064] The controller 118 controls the ejection of printing material from the ejection nozzles 206 onto the print zone sp1 of the substrate 508 based on the mapped position of the ejection nozzles 206 within the printing system reference frame described with reference to Figures 3A and 3B and the mapped position of the print zone sp1 within the printing system reference frame described with reference to Figure 5B. In one embodiment, this control of the ejection of printing material includes physical adjustments of the substrate 508 and / or the print head assembly 119 and / or logical modifications of the printing data used to generate the control signals for the ejection nozzles 206. The mapped positions of the ejection nozzles 206 and the print zone sp1 accurately reflect the actual positions of the ejection nozzles 206 and the print zone sp1, thereby improving printing accuracy.

[0065] In at least one embodiment, while one print area of ​​a substrate is being printed, substrate marks for identifying another print area on the same substrate are imaged and recognized. For example, while print area sp1 of substrate 508 is being printed by moving substrate 508 back and forth in the Y direction, substrate marks 520, 522, 524, and 526 for identifying another print area sp3 are imaged during the same back and forth movement of substrate 508 in the Y direction. Thus, when the printing operation of print area sp1 is completed, print area sp3 is immediately ready for printing because substrate marks 520, 522, 524, and 526 have already been detected and the position of the corresponding print area sp3 has already been mapped to the reference frame of the printing system. Therefore, in at least one embodiment, the printing process for the entire substrate 508 can be sped up.

[0066] 6 is a flowchart of a printing method 600 according to one embodiment. In one embodiment, printing method 600 may be implemented in printing system 500 by or under the control of at least one controller, as described herein. In the following description, printing method 600 is implemented by or under the control of controller 118.

[0067] In operation 605, the controller causes the first imaging device to capture at least one first image including a plurality of first marks to determine the positions of a plurality of ejection nozzles of the print head assembly. For example, as described with respect to FIG. 2B , the controller 118 moves the print head assembly 119 past the line scan imaging device 202 near the image capture location. The controller 118 also causes the line scan imaging device 202 to capture a first image of the nozzle face 321 of the print head assembly 119 while the print head assembly 119 passes the line scan imaging device 202 in the X direction. The first captured image includes at least a plurality of marks 310, 312, 314, 316 of the print head assembly 119.

[0068] In operation 615, the controller causes the second imaging device to capture at least one second image including a plurality of second marks to determine the location of the print area on the substrate. For example, the controller 118 causes the imaging device 502 to capture at least one second image of the substrate 508 that is expected to include substrate marks 510, 512, 514, 516 identifying print area sp1 (or substrate marks 520, 522, 524, 526 identifying print area sp3) while the substrate 508 passes in the Y direction below the imaging device 502. The substrate 508 is passed in the Y direction below the imaging device 502 before the printing operation of the substrate 508 (e.g., identifying print area sp1) or during the printing operation of the substrate 508 (e.g., identifying print area sp3 while printing print area sp1).

[0069] In operation 625, the controller controls the ejection of printing material from the multiple ejection nozzles into the print area of ​​the substrate based on at least one first image and at least one second image. For example, the controller 118 detects or recognizes multiple marks 310, 312, 314, and 316 from the first acquired image of the print head assembly 119 to determine the position of the ejection nozzle 206, and detects or recognizes multiple substrate marks 510, 512, 514, and 516 from the second acquired image of the substrate 508 to determine the position of the print area sp1. The controller 118 then maps the determined positions of the ejection nozzle 206 and the print area sp1 to corresponding positions in the reference frame of the printing system. The controller 118 then uses the mapped positions of the ejection nozzle 206 and the print area sp1 in the reference frame of the printing system to control when the ejection nozzles eject printing material and / or the selection of which ejection nozzles to use in accordance with print data or a recipe including coordinates in the reference frame of the printing system. As a result, a printed product with high printing accuracy can be obtained.

[0070] The methods described above include example operations that do not necessarily need to be performed in the order described. Operations may be added, substituted, reordered, and / or deleted as needed in accordance with the spirit and scope of the embodiments of the present disclosure. Embodiments that combine different features and / or different embodiments are also within the scope of the present disclosure and would be apparent to one of ordinary skill in the art upon review of the present disclosure.

[0071] Figure 7 is a block diagram of a controller according to one embodiment. One or more of the units and / or systems and / or operations described with respect to Figures 1 to 6 are implemented, in one embodiment, by one or more controllers 700 of Figure 7.

[0072] The controller 700 includes a hardware processor 702, a storage device 704 including at least one non-transitory computer-readable storage medium, a bus 708, an I / O (input / output) interface 710, and a network interface 712. The processor 702 is coupled to the storage device 704, the I / O interface 710, and the network interface 712 via the bus 708. The network interface 712 is connectable to a network 714, thereby enabling the processor 702 and the storage device 704 to communicate with other devices via the network 714. The processor 702 is configured to execute computer program instructions encoded in and / or access data stored in the storage device 704 to cause the controller 700 to perform one or more functions and / or operations described with respect to FIGS.

[0073] The processor 702 may include one or more of a central processing unit (CPU), multiprocessor, distributed processing system, application specific integrated circuit (ASIC), and / or suitable hardware processing unit.

[0074] Storage device 704 includes one or more electronic, magnetic, optical, electromagnetic, infrared, and / or semiconductor systems (or apparatus or devices) for non-transient storage of instructions and / or data. For example, storage device 704 includes semiconductor or solid-state memory, magnetic tape, removable computer diskettes, random access memory (RAM), read-only memory (ROM), rigid magnetic disks, and / or optical disks. Examples of optical disks, storage device 704 includes compact disc-ROM (CD-ROM), rewritable compact disc-R / W (CD-R / W), and / or digital video disks (DVD).

[0075] I / O interface 710 is a circuit that can be connected to external circuitry. For example, I / O interface 710 includes one or more of a keyboard, keypad, mouse, trackball, trackpad, cursor direction keys, card reader, communication port, display, signal lights, printer, and / or audio device for communicating information to and from processor 702. In one example, I / O interface 710 is omitted.

[0076] The network interface 712 is circuitry that enables the controller 700 to communicate with a network 714 to which one or more other controllers and / or image acquisition / processing devices are connected. For example, the network interface 712 includes one or more of a wireless network interface, such as BLUETOOTH, WIFI, WIMAX, GPRS, WCDMA, etc., or a wired network interface, such as ETHERNET, USB, IEEE-1394, etc. In one example, the network interface 712 is omitted.

[0077] The control unit 700 is configured to perform some or all of the functions and / or operations described with respect to Figures 1 to 6, and may therefore achieve one or more of the benefits and / or effects described with respect to Figures 1 to 6.

[0078] The foregoing outlines features of several embodiments so that those skilled in the art may better understand aspects of the present disclosure. Those skilled in the art will appreciate that this disclosure may readily be used as a basis for designing or modifying other processes and structures which carry out the same purposes and / or achieve the same advantages as the embodiments described herein. Those skilled in the art will also appreciate that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present disclosure.

Claims

1. A printing system, the printing system comprising: a substrate support; a print support; a printhead assembly movably coupled to the print support; The printhead assembly includes: a plurality of discharge nozzles extending in a discharge direction toward the substrate support; a plurality of marks; The printing system further comprises: an imaging device coupled to the print support, the print head assembly and the imaging device being movable relative to one another, the imaging device being oriented in a direction opposite to the ejection direction to capture an image including the plurality of marks; the print head assembly is positionable within an imaging field of view of the imaging device such that the imaging device can capture the image while the print head assembly passes near the imaging device, and the imaging device is a line scan imaging device.

2. The control unit further includes: mapping the position of each of the nozzles of the printhead assembly to a corresponding position in a frame of reference of the printing system; and controlling ejection of printing material from the nozzles based on the mapped positions of the nozzles in the frame of reference of the printing system.

3. The control unit, from the image captured by the imaging device, the plurality of marks; detecting a nozzle among the plurality of discharge nozzles; determining a position of each of the nozzles in the printhead assembly; the detected mark; The printing system of claim 2 , further comprising: determining based on the detected nozzles.

4. each of the marks has a predetermined position relative to the plurality of discharge nozzles; The printing system further includes a control unit, detecting the mark from the image captured by the imaging device; the detected mark; a predetermined position of the mark; and determining a position of each of the nozzles in the printhead assembly based on the determined position of each of the nozzles in the printhead assembly.

5. The printing system of claim 1 , wherein the imaging device is stationary relative to the substrate support.

6. The printing system of claim 5 , wherein the nozzles are arranged in at least one row along the cross-scan direction.

7. 7. The printing system of claim 6, further comprising a controller, the controller comprising the step of controlling the imaging device to capture an image that includes all of the nozzles in a single pass of the print head assembly in the cross-scan direction by the imaging device.

8. A printing system, comprising: a substrate support; a print support extending across the substrate support; a printhead assembly movably coupled to the print support; The printhead assembly comprises: a printhead having a plurality of nozzles facing the substrate support; Housing and a plurality of marks on the housing; and The printing system includes: a line scan imaging device, wherein the line scan imaging device and the print head assembly are relatively movable to position the nozzle and the plurality of marks within a field of view of the line scan imaging device to capture an image, and the print head assembly and the line scan imaging device move relative to each other such that the image includes the plurality of marks and the plurality of nozzles; and The printing system includes a control unit that controls the ejection of printing material from the nozzles based on the image captured by the imaging device.

9. the control unit detects each of the marks and one nozzle of the plurality of nozzles from the image captured by the imaging device; 9. The printing system of claim 8, further comprising: determining a position of each of the nozzles based on the detected marks and the detected nozzles.

10. The printing system of claim 9 , wherein the controller is configured to map the position of each of the nozzles into a reference frame of the printing system.

11. 10. The printing system of claim 9, wherein the controller controls the imaging device to capture the image in a single cross-scan pass of the printhead assembly.

12. The printing system of claim 11 , wherein the nozzles are arranged in at least one row along the cross-scan direction.

13. A printing method, the printing method comprising: capturing images of a plurality of fiducial marks on the printhead assembly with an imaging device; detecting the plurality of fiducial marks in the image captured by the imaging device; determining positions of a plurality of ejection nozzles within the printhead assembly based on the detected plurality of fiducial marks; and discharging printing material from the plurality of discharge nozzles onto the substrate while moving the substrate relative to the print head assembly based on the detected positions of the plurality of discharge nozzles, The printhead assembly includes: a housing having the plurality of fiducial marks; a plurality of printheads removably mounted to the housing; and Each of the plurality of print heads a corresponding set of ejection nozzles from a plurality of ejection nozzles in the printhead assembly; a printhead mark having a predetermined position relative to the corresponding set of ejection nozzles; and The printing method includes: detecting print head marks of the plurality of print heads from the image captured by the imaging device; determining positions of the plurality of ejection nozzles in the printhead assembly based on the detected plurality of reference marks on the housing, the detected printhead marks of the plurality of printheads, and predetermined positions of each of the printhead marks relative to the corresponding set of ejection nozzles.

14. 14. The printing method of claim 13, further comprising the step of mapping the determined positions of the plurality of discharge nozzles in the print head assembly to corresponding positions in a reference frame, wherein the step of discharging printing material from the plurality of discharge nozzles is performed based on the mapped positions of the plurality of discharge nozzles in the reference frame.

15. detecting one discharge nozzle from the image captured by the imaging device, 14. The printing method of claim 13, wherein determining the positions of the plurality of ejection nozzles in the printhead assembly is performed based on the detected plurality of fiducial marks and the detected ejection nozzles.

16. The printing method of claim 13, wherein the step of capturing at least one of the images is performed while the print head assembly is moving in a cross-scan direction to pass near the imaging device.

17. the imaging device is a line-scan imaging device having a plurality of image sensors arranged in a line along a scan direction orthogonal to a cross-scan direction, the plurality of ejection nozzles are arranged in at least one line along the cross-scan direction, 14. The method of printing of claim 13, wherein the image is captured by the line scan imaging device by a single pass of the print head assembly near the line scan imaging device.

18. 18. The printing method of claim 17, wherein the scan direction is the Y direction and the cross-scan direction is the X direction.

19. A printing system, comprising: a substrate support portion that supports a substrate; a holder assembly for moving the substrate along the substrate support in a scanning direction; a printhead assembly disposed opposite the substrate support and movable in a cross-scan direction, the printhead assembly comprising: a plurality of discharge nozzles extending in a discharge direction toward the substrate support; a plurality of marks; and The printing system includes: a line scan imaging device oriented in a direction opposite to the ejection direction for capturing an image including the plurality of marks; the print head assembly is movable to position the nozzles and the marks within a field of view of the line scan imaging device so that the line scan imaging device can capture the image, and the print head assembly and the line scan imaging device are capable of relative motion; The line scan imaging device has a plurality of image sensors arranged linearly along the scanning direction.

20. 20. The printing system of claim 19, wherein the line scan imaging device is stationary relative to the substrate support.

Images