Induced transport route correction

Abstract

To provide suited induction-type transport path correction.SOLUTION: A printer deposits a material onto a substrate as a part of a manufacturing process for an electronic product. At least one transported component experiences an error that affects the deposition. The error is mitigated using transducers that equalize a position of the component, e.g., to provide an "ideal" conveyance path to thereby allow precise droplet placement despite the error. In one embodiment, an optical guide (e.g., laser) is used to define a desired path and a sensor mounted on the component dynamically detects a deviation from the path, and the deviation then drives the transducers and is used to counteract the error immediately. An error correction method herein corrects more than a type of transportation error so that the same can be applied to correct, errors in, for example, a substrate transport path, a printhead transport path and / or split-axis transportation non-orthogonality.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] This disclosure claims the benefit of U.S. Patent Application No. 15 / 642,188, filed July 5, 2017 on behalf of first named inventor Eliyahu Vronsky, entitled "Guided Transport Path Correction," U.S. Provisional Application No. 62 / 489,768, filed April 25, 2017 on behalf of first named inventor Digby Pun, entitled "Transport Path Correction Techniques And Related Systems, Methods And Devices," and U.S. Provisional Application No. 62 / 359,969, filed July 8, 2016 on behalf of first named inventor Digby Pun, and U.S. Provisional Application No. 62 / 459,402, filed February 15, 2017 on behalf of first named inventor David C. Darrow, entitled "Precision Position Alignment, Calibration and Measurement in Printing And Manufacturing Systems," each of which is incorporated herein by reference.This disclosure also relates to the following documents: U.S. Patent No. 9,352,561 (USSN 14 / 340403), filed as application on July 24, 2014 on behalf of first inventor Nahid Harjee for “Techniques for Print Ink Droplet Measurement And Control To Deposit Fluids Within Precise Tolerances,” U.S. Patent Publication No. 20150360462 (USSN 14 / 738785), filed as application on June 12, 2015 on behalf of first inventor Robert B. Lowrance for “Printing System Assemblies and Methods,” and U.S. Patent Publication No. 20150298153 (USSN 14 / 738785), filed as application on June 30, 2015 on behalf of first named Michael Baker for “Techniques for Arrayed Printing of a Permanent Layer with Improved Speed ​​and Accuracy.” No. 14 / 788609, and U.S. Patent No. 8,995,022, filed as application on August 12, 2014 on behalf of first named inventor Eliyahu Vronsky for “Ink-Based Layer Fabrication Using Halftoning To Control Thickness.” [Background technology]

[0002] One type of industrial printer can be applied to precision manufacturing, for example, the fabrication of electronic devices.

[0003] To take one non-limiting example, an inkjet printer can be used to deposit one or more ultra-thin layers of an electronic display device or a solar panel device. The "ink" in this case differs from the traditional concept of ink as a dye of a desired color, and can instead be organic monomers that diffuse and mix together somewhat but are not absorbed, deposited instead as discrete droplets that maintain an intentional layer thickness that serves to impart structural, electromagnetic, or optical properties to the finished device. Inks are also typically intentionally made to be translucent, and the resulting layer is used to generate and / or transmit light. Successive coats of ink deposited by printing are then processed in place (e.g., cured using ultraviolet light or otherwise baked or dried) to form a permanent layer with a very tightly tuned thickness, e.g., 1-10 microns, depending on the application. These types of processes can be used to deposit various conductors, such as hole injection layers ("HIL"), hole transport layers ("HTL"), hole transport layers ("HTL"), emissive or emissive layers ("EML"), electron transport layers ("ETL"), electron injection layers ("EIL"), anode or cathode layers, hole blocking layers, electron blocking layers, polarizers, barrier layers, primers, encapsulation layers, and other types of layers of an OLED pixel. The referenced materials, processes, and layers are merely exemplary. In one application, the ink can be deposited to create layers within each of many individual electronic components or structures within individual microscopic fluid reservoirs (e.g., within "wells") to form individual display pixels or solar cell layers, for example. In another application, the ink can be deposited to form one or more encapsulation layers that have macroscopic dimensions, for example, covering many such structures (e.g., spanning a display screen area with millions of pixels).

[0004] The required precision can be very fine; for example, a manufacturer's specifications for fabricating a thin layer of an organic light-emitting diode ("OLED") pixel may specify a condensed fluid deposition in a pixel well to picoliter resolution (or even to a higher level of precision). Even slight local variations in the volume of deposited fluid from the specifications can create problems. For example, variations in ink volume between structures (e.g., between pixels) can create hue or intensity differences or other performance differences that are noticeable to the human eye. In encapsulation or other "macroscopic" layers, such variations can impair layer function (e.g., a layer may not reliably seal electronic components sensitive to unwanted particulate matter, oxygen, or moisture) or create otherwise observable differences. As devices become smaller and smaller, these problems become even more significant. It will be appreciated that a typical application may feature a printer having tens of thousands of nozzles depositing discrete droplets, each having a volume of 1 to 30 picoliters ("pL"), and when it is considered that manufacturing process corners for printheads can lead to inoperable nozzles and individual errors in droplet size, nozzle location, droplet velocity, or droplet landing position, thereby causing localized ink volume delivery variations, there is an enormous challenge in producing thin, homogenous layers that closely follow the desired manufacturing specifications.

[0005] One source of error in achieving fine accuracy relates to the use of mechanical components in the fabrication process relative to the scale of the product being manufactured. As a non-limiting example, most printers have a mechanical transport system that moves one or more printheads, the substrate, or both to perform printing. Some printers may also feature transport systems for rotating or offsetting components (e.g., moving or rotating the printheads to change the effective pitch between the nozzles), each of which may impart fine mechanical or positioning errors and thus lead to non-uniformity. For example, even if these transport systems typically rely on high-precision components (e.g., precision tracks or edge guides), they may still impart jitter or translational or rotational inaccuracies (e.g., deviations on the scale of millimeters, microns, or smaller in the transport path) that make it difficult to achieve the required accuracy and uniformity throughout the transport path length used in production. To provide some context, equipment used to fabricate large HDTV screens may feature "room-sized" printers controlled to deposit ultra-thin layers of material onto meter-wide by meter-long substrates, where individual droplet deliveries are planned to nanometer-scale coordinates. Transport paths in such equipment may be meters in length. It is noted that there are many other mechanical components in such systems that may introduce some form of error, for example, transport path systems used to exchange printheads, camera assemblies that align or inspect the substrate, and other types of moving parts. In such systems, even mechanical parts with very fine precision may generate deviations that affect the nanometer-scale coordinates referenced above. Thus, the layers required become thinner and thinner, and the precision required becomes smaller and smaller relative to the product being fabricated, making it even more imperative to carefully control and / or mitigate potential sources of positional error.

[0006] Generally, there are several conventional techniques for reducing position and translation errors in these types of processing systems. First, the substrate can be roughly aligned with the printer transport and then finely aligned manually (potentially repeatedly during the processing process). Such a process is time-consuming, i.e., generally impeding the goal of having an automated high-speed assembly line type process for producing consumer products. It is also generally extremely difficult to obtain the required micron or nanometer accuracy using such manual processes. There are also some errors that cannot be adequately addressed using such techniques, such as errors caused by differences in the transport path as just introduced above (e.g., errors that appear after the substrate is aligned). As a second example, US Patent Publication No. 20150298153 relates to a process of measuring fine position and / or rotation errors in substrate position and correcting these errors in software, for example, by reallocating the nozzles used to print or by changing the nozzle drive waveforms used to fire the nozzles otherwise. In other words, generally speaking, these techniques attempt to "live with" minute position and rotation errors (thereby preserving printing speed) and then adjust the nozzles used, and when and how those nozzles are electronically controlled, to correct for the errors (e.g., using a pre-planned raster without having to readjust an error-dependent scan path). However, despite the usefulness of compensating for alignment errors in software, measuring and accounting for this error in software and recalculating firing allocations for thousands of nozzles can require significant computational resources and time.

[0007] What is needed are additional techniques for correcting motion, rotation, and position errors in mechanical systems in manufacturing equipment. Still further, what is needed are techniques for correcting errors in moving components of a manufacturing system to simulate an "ideal" edge or transport path. Such techniques, when applied to precision manufacturing processes, and in particular to printing systems of the type described, would reduce the need for significant computational resources and time to re-render raster control data, leading to an overall simpler and / or faster and / or more accurate printing process. The present invention addresses these needs and provides further related advantages. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 illustrates a substrate 103 as it is transported through an industrial printing system along a transport path 107. To its right, FIG. 1 shows the substrate in two hypothetical positions (103′ and 103”) with respective rotational and translation errors (Δx, Δy, and Δθ). The transport path errors and associated substrate rotation and translation errors are considered to be exaggerated relative to the scale of the drawing to aid in illustration.

[0009] [Figure 2A] 2A is a schematic diagram of a system 201 for dynamically correcting mechanical errors. A first component 203 travels along a transport path 206 (generally aligned with the "y" axis in this example), mirrors 211 / 212 and sensors 208 / 209 detect deviations from an optical guide 202 (e.g., a laser beam), and during the travel of the first component, transducers 216 and 217 are automatically driven in response to signals from sensors 208 / 209 to equalize deviations (e.g., in one or more dimensions, such as x, z, and / or θ) so that a second component 205 follows an ideal path despite mechanical errors.

[0010] [Figure 2B]FIG. 2B is a flow chart associated with correcting position and / or rotational errors as a transported component is advanced along a transport path.

[0011] [Figure 3A] Figure 3A is a schematic diagram showing one or more transducers performing fine mechanical adjustments and correcting the errors referred to in relation to Figure 1 (i.e., in this example as part of the "gripper" that advances the substrate). As described, an optical guide such as a laser source 319 can be used to define a desired path, and deviations from this path are sensed by one or more sensors 320. One or more transducers "T" are driven in response to this deviation, with the result (in this example) that the substrate travels a "perfectly straight" or "jitter-free" transport path.

[0012] [Figure 3B] Figure 3B depicts a transport path 107 with mechanical imperfections similar to Figure 1. However, in this case, a transducer "T" as introduced relative to Figure 3A is used to perform fine adjustments of the substrate position and / or orientation as the gripper advances on the path 107. The result is that the substrate now moves according to an "ideal" motion (e.g., a perfectly straight "ideal" edge and / or a path containing no jitter), as represented by the imaginary straight edge 323.

[0013] [Figure 3C] Figure 3C is similar to Figure 3B in that it illustrates the use of a transducer "T" to correct for transport path errors, however, in this case errors also potentially arise from a second transport path 356, which in this case exhibits a non-ideal position or orientation of the print head (or camera or other assembly) as it is transported in the general direction of arrow 354.

[0014] [Figure 3D]FIG. 3D is similar to FIG. 3C in that it depicts the movement of the print head along edge or track 356, but as shown, the print head assembly now also has its own optical guide 371 and transducer assembly to provide fine position and rotation corrections that mitigate errors in the edge or track 356, the result being that the print head now also effectively travels a hypothetical "ideal" path 325 (or 369 as will be discussed below).

[0015] [Figure 3E] Figure 3E is similar to Figure 3C in that it depicts the motion of the print head along an edge or track 356. However, while the print head transport path has optical guides, corrections to match the print head jitter are instead applied by a transducer-based error correction system associated with another transport path, in this case transducers associated with the gripper.

[0016] [Figure 3F] FIG. 3F is an illustrative diagram showing a mechanism for correcting transport path errors, for example, by implementing compensatory counter-motions (or other error mitigation) in up to six different degrees of freedom (e.g., potentially including three translational degrees of freedom, plus yaw, pitch, and / or roll).

[0017] [Figure 4A] 4A provides a plan view of a substrate and illustrates the raster or scanning process. The shaded areas 407 represent a single scan path, while the transparent areas 408 represent alternative paths. As indicated by the dimensional legend in the figure, in this example, the "x" axis corresponds to the cross-scan dimension, while the "y" axis corresponds to the in-scan dimension.

[0018] [Figure 4B] FIG. 4B provides a top schematic view of a processing machine that includes multiple modules, one of which (415) features a printer within a controlled atmosphere.

[0019] [Figure 4C] FIG. 4C is a block diagram illustrating one method 431 for dynamically correcting transport path errors in an industrial printing system.

[0020] [Diagram 5] FIG. 5 is an illustrative diagram showing a series of optional layers, products, or services that can each independently embody the techniques introduced herein; for example, these techniques can be implemented in the form of software (by numeral 503), or as printer control data (by numeral 507) used to control a printer to print on a substrate or otherwise correct errors, or as products made relying on these techniques (e.g., as illustrated by numerals 511, 513, 515, or 517).

[0021] [Figure 6A] FIG. 6A is a detailed perspective view of one embodiment of an industrial printer, such as the printer inside the print module of FIG. 4B.

[0022] [Figure 6B] FIG. 6B is a detailed perspective view of an embodiment of a gripper.

[0023] [Figure 6C] FIG. 6C is a close-up perspective view of the transducer assembly from the gripper of FIG. 6B.

[0024] [Figure 6D] FIG. 6D is a close-up perspective view of the floating mechanical pivot assembly from the gripper of FIG. 6B.

[0025] [Figure 6E] FIG. 6E is a schematic perspective view of the error correction system represented by FIGS. 6B-6D, with emphasis on the design of the floating mechanical pivot assembly.

[0026] [Figure 7A]FIG. 7A shows an embodiment 701 in which an optical guide 702 is used to ensure linear motion of a gripper 703 and a substrate 704 .

[0027] [Figure 7B] FIG. 7B shows an embodiment 713 in which the laser source and / or light redirecting optics are mounted to an offsettable component of the gripper or other element being transported.

[0028] [Figure 7C] FIG. 7C shows an embodiment 719 in which a sensor 720 is used to calibrate a light source 721, for example, to detect and / or correct a path error 722 relative to an intended path 723.

[0029] [Figure 7D] Figure 7D shows an embodiment 727 in which the light source 728 is improperly aligned. However, unlike the embodiment of Figure 7C, the deviation between the incorrect optical path 729 and the correct optical path 730 is electronically corrected by using transducers (represented by arrow icons 732A / 732B) to implement compensating offsets. The signals that control these offsets can be stored in digital memory and read out during system operation, or otherwise added to the dynamic correction depending on the transport path position, so that the transported component follows the correct path 730.

[0030] [Figure 7E] 7E shows an embodiment 735 that implements a zero target control loop. Sensors 736A / 736B dynamically detect deviations from a desired path in one or more dimensions (in this case represented by the deviation between a "line of sight" 737A / 737B and a beam 738 from a laser source 739). A motion controller 741 provides feedback that drives transducers 742A / 742B to constantly drive the error to zero.

[0031] [Figure 7F]7F shows an embodiment 745 in which transducers 746A / 746B are driven to keep the transported object (e.g., gripper 747 and substrate 748) always horizontal with respect to the optical guide 749. In this case, sensors 750A / 750B detect deviations of portions of the substrate and / or gripper from the optical guide 749 and drive the two transducers 746A / 746B to even out jitter in altitude or otherwise precisely control the altitude.

[0032] [Figure 7G] 7G shows an embodiment 755 that uses two parallel transport systems 756A / 756B for a given transport direction. In this case, each transport system has its own optical guide 757A / 757B and transducer compensation system 759A / 759B. One of the transport systems 756B also carries another light source 765 that generates an optical guide 766 that is used to align and synchronize the two transport systems 756A / 756B. A signal from a detector 767 on the second transport system 756A is fed to a motion controller 763 to maintain synchronization between the transport systems.

[0033] [Figure 7H] 7H shows an embodiment 771 in which two transport systems 772 and 773 each have their own source 774 / 775 and motion controller 780 / 781. The result is that each motion controller 780 / 781 receives an individual (absolute position coordinate) command signal 782 / 783 and is able to establish the appropriate position relative to the system coordinate reference system, with errors being corrected transparently to the general system motion control.

[0034] [Figure 7I]7I shows an embodiment 787 in which two transport systems 788 / 789 each have their own source 790 / 791 and sensor pair 792A,B / 793A,B, but only one system has a transducer-based error correction system (794A / B). In this case, a motion controller 795 generates transducer control signals 796A / 796B such that one of the transport systems (789) compensates for errors associated with the other transport system 788. Non-motion errors such as errors in alignment of the optical guides for either the transport systems and / or non-orthogonality between the transport systems can also be corrected.

[0035] [Figure 8A] FIG. 8A is a cross-sectional view of an assembly that uses two different sets of transducers "T" to correct errors in more than one dimension.

[0036] [Figure 8B] FIG. 8B is a cross-sectional view of another assembly that uses two different sets of transducers "T" to correct errors in more than one dimension.

[0037] The subject matter defined by the recited claims may be better understood by reference to the following detailed description, which should be read in conjunction with the accompanying drawings. This description of one or more specific embodiments, which are designed below to enable one to build and use various implementations of the techniques described by the claims, is not intended to limit the recited claims, but to illustrate their applications. Without limiting the foregoing, the present disclosure provides several different examples of techniques for mitigating transport path errors in a manufacturing apparatus or printer, and / or for processing thin films for one or more products of a substrate as part of a reproducible printing process. The various techniques can be embodied in various forms, for example, in the form of a printer or manufacturing apparatus or components thereof, in the form of control data (e.g., pre-calculated correction data or converter control data), or in the form of an electronic or other device that is processed as a result of these techniques (e.g., having one or more layers produced according to the described techniques). Although specific examples are presented, the principles described herein may also be applied to other methods, devices, and systems. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The present disclosure provides a method for correcting transport path errors and / or providing a method for ... Improved techniques for processing layers are provided. In one embodiment, these techniques are applied to a manufacturing apparatus or system that produces layers of an electronic display, solar panel, or another electronic device, or indeed any other type of precision device or product. The manufacturing or processing system includes a transport system, where components will be guided along a transport path to aid in manufacturing. The path length is typically quite long relative to the required positioning accuracy. In a typical implementation, for example, the transport path length can be meters, but the required positioning can be on the micron scale or even finer (e.g., nanometer scale or finer). To aid in precise positioning, one or more sensors are used to detect deviations between the components and the light beam in one or more dimensions. Deviations detected by the one or more sensors are then used to derive position correction signals that are fed to one or more transducers and used to offset the deviations, with the result that the components track the optical path despite the fine mechanical errors associated with the transport path. In one embodiment, the one or more sensors provide feedback that forces the transducers to constantly "zero" the position and rotation errors.

[0039] More specifically, these techniques can be optionally applied to printers used to fabricate electronic products, where the printer deposits material on a substrate at precise coordinates. A transport system in this context can be any mechanical system used by the printer, such as a gripper used to advance the substrate, a printhead motion system used to transport the printhead (e.g., orthogonal to the gripper motion), a camera transport system, a flight altitude or printhead altitude adjustment system, and other types of assemblies. In the discussion immediately following, examples will be described in which these techniques are applied to gripper path adjustment. It should be understood that the techniques described herein are not limited to gripper transport systems, nor to the general context of printers. Conversely, it should also be understood that these techniques can be optionally applied to two or more transport or transportation systems in a manufacturing system, such as to control any of the x, y, and / or z positions, or associated rotational degrees of freedom, as desired. In one embodiment discussed below, these techniques are applied independently to each of the gripper and print head transport paths and used in coordination with a position feedback system for each transport path to provide precise position positioning in the x, y, and / or z axes and to ensure coordinate system orthogonality and precise position control within the printing system.

[0040] In one example, a meter-long by meter-wide glass substrate would be introduced into a "room-sized" printer, which would print individual droplets of "ink" at very precise coordinates (e.g., in precise nanometer or sub-nanometer coordinates). Two transport systems are used to position the droplets, including a "gripper" that advances the substrate back and forth along a "fast" or "in-scan" direction, and a printhead transport system that moves the printhead in a "slow" or "cross-scan" direction (e.g., the printhead is repositioned during subsequent scans so that printing occurs in swaths as the substrate moves under the printhead). In variations, both systems can be moved simultaneously, or the printhead or substrate can be stationary while the other moves in two or more dimensions. Droplet landing locations are typically selected so that the deposited droplets mix together on the glass substrate to provide gapless area coverage, forming a liquid coat without pinholes, gaps, or other defects. The "ink" is different from the conventional notion of ink for a graphics printer, and is typically a relatively viscous material (e.g., an organic monomer) that is colorless, or alternatively described, where the natural color of the material is not important. The ink is typically not absorbed and spreads only to a limited extent so that the finished layer provides a specifically desired layer thickness or other specifically desired electronic, magnetic, light generating, structural, or similar properties. For example, the ink can be an organic monomer in one embodiment, and the deposited coat (once the droplets are sufficiently mixed) is then cured using ultraviolet light to form a polymer layer. The liquid coat, once formed, is then hardened, dried, cured, developed, or otherwise treated ("treated") to form a permanent or semi-permanent layer of the electronic product being fabricated on the glass substrate. These techniques can be used to deposit light generating layers, encapsulation layers, and potentially other types of layers for individual pixels of an electronic display.For example, the techniques disclosed herein can be applied to a wide variety of manufacturing processes, including, but not limited to, the deposition of precision coatings for "smart windows" and other types of electronic, optical, or other devices. Note that when used to form layers of precision electronic components (e.g., micron- or nanometer-scale structures), each droplet in the foregoing examples must typically be deposited at very fine position coordinates; for example, too much or too little ink, or a poorly placed droplet, can result in a defective or suboptimal component. Precision mechanical parts (e.g., tracks or edge guides) are used to help ensure precise motion, but these systems can still introduce mechanical jitter that interferes with proper droplet placement.

[0041] In embodiments herein, to correct this problem, a transport system (e.g., gripper) can have two components, including a first (or "track-guided") component that moves along a transport path, and a second (or "offsetable") component, where one or more transducers are used to offset the second component relative to the first component. For example, the first component follows a track, while the second component carries a vacuum chuck that is used to engage the substrate. In other embodiments, other techniques can be used to engage and / or transport the substrate. When the first component experiences jitter and error, the error is detected and used to drive a transducer that causes the second component to offset the error so that the substrate travels along an ideal path. In one embodiment, this is accomplished by using a laser beam and / or optics and / or detectors to mark the ideal path, and the second component carries one or more of these optical components in such a manner that it detects deviations of the second component from the marked ideal path. The detected deviation is used to instantly drive the transducer to counter the deviation. In one implementation, a simple two-cell detector can be used to detect path deviation in one dimension, while in another implementation, a four-cell or more complex design can be used to detect errors in two or more dimensions. For example, in the context of the example presented above, a glass substrate can be supported on an air bearing (i.e., above a gas floating table), while a gripper can use suction to selectively engage and then transport the substrate. The "second component" of the gripper, in one embodiment, can be offset in the cross-scan dimension and in altitude to match (or otherwise equalize) the fly height of the substrate above the air floating table. Of course, other implementations will occur to those skilled in the art. As noted above, the techniques described herein can be applied to a wide variety of manufacturing and / or transport systems (e.g., application to printers, grippers, printheads, or similar components is considered "optimal").

[0042] It should be noted that whatever the source of error (e.g., whether due to a "repeatable" error or otherwise to the transport system), the techniques described herein instantly correct the position of what is being transported so as to undergo ideal motion, at least in one or more dimensions orthogonal to the direction of transport. These techniques are particularly useful when precise position and / or orientation control is desired, for example, in assembly line type processes, where each substrate or each product may be subject to minute repeatable or non-repeatable position and / or orientation errors.

[0043] To correct and / or mitigate the errors, in one embodiment, fine positioning transducers are driven without a fixed pivot point to counter mechanical imperfections. These transducers perform fine adjustments of the substrate position and / or orientation, thereby countering the effects of mechanical imperfections in at least one dimension. In this way, the transport system (e.g., gripper, substrate, print head, camera, or other transport path) continues to be characterized by mechanical imperfections, but the motion of the substrate and / or print head is performed to approximate an ideal progression. In one embodiment, the transport path is substantially linear, and the transport occurs substantially along a first dimension (e.g., the "y" dimension), while the two or more transducers each independently apply a linear offset in an independent dimension (e.g., the "x" dimension). When driven in common mode, these transducers allow the offset of imperfections associated with the transport system that affect the "x" dimension position of the substrate. For example, the transported object can be made to travel a virtual straight edge in the "y" dimension. When driven in differential mode, the transported object can also be rotated in the "xy" plane to correct for orientation errors similarly caused by mechanical imperfections in the transport path. Note that three or more transducers can be used to simultaneously correct errors in multiple dimensions, for example to "equalize" gripper or printhead elevation, as will be discussed further below.

[0044] In a split-axis system used to fabricate electronic devices on a substrate, a "gripper" can be used to move the substrate along a first dimension (e.g., the "y" dimension). The gripper has a first component that rides along an edge or track and a second component (typically a vacuum device) that engages and locks onto the substrate. A transducer can be operatively positioned between the first and second components to provide selective offsets between the first and second components at two or more discrete points of interaction, providing both common mode and differential mode displacements as referenced above. When the first component experiences translational and rotational deflections caused by mechanical imperfections in the transport system (e.g., in the second dimension), the transducer is driven to precisely equalize these deflections in that dimension, essentially providing the second component with a "virtual edge" or "virtual transport path" that is not characterized by mechanical errors. Note that the errors can be linear and nonlinear, and the corrections can be correspondingly linear and nonlinear. In optional embodiments, this type of system can be embodied in a printer or printing system, for example, where the y dimension is the substrate transport dimension and / or one of the "in-scan" or "cross-scan" dimensions, and the x dimension is the print head transport dimension and / or the other of the "in-scan" or "cross-scan" dimensions. Note that the frames of reference described are arbitrary and can be inverted or exchanged for other frames of reference or other degrees of freedom.

[0045] As described, there may be multiple transport paths in a manufacturing system, and these techniques may be applied to any one or combination of these transport paths, and may be applied to correct for positional errors (or rotational errors) in one dimension or errors in multiple dimensions. A few examples will help highlight this point.

[0046] First, in one contemplated implementation, these techniques are used to correct cross-scan dimension errors in the substrate position as the gripper moves along the transport path. The gripper has a first and second component as referenced above and a linear transducer operatively coupling these components at at least two interaction points, the transducer structured to provide a "floating" pivot point. As the first component progresses along the transport path, deviations from the optical guide or desired optical orientation are detected. Signals generated from this detected deviation are used to control the transducer to provide "common mode" and "differential mode" offsets that repeatedly provide translation offsets or rotational adjustments of the substrate in the cross-scan dimension to drive the deviation or error to zero. The substrate is thus advanced in a linear path despite mechanical imperfections in the transport system. Various embodiments of the described transducers will be provided below, but briefly, in one embodiment, a "voice coil" can be used for these transducers to provide a very precise microscopic throw. A floating mechanical pivot assembly compatible with common and differential drive modes can also optionally be used to help provide structural support and interconnection between the first and second components. In other embodiments, piezoelectric or other transducers can be used instead.

[0047] In an optional extension to this first example, the gripper position (and / or the position of a second component of the gripper) can also be adjusted in the in-scan dimension. For example, in one embodiment, the electronic drive signal (used to advance the gripper or otherwise trigger printer nozzle firing) is adjusted to correct for position error of the substrate in the in-scan dimension. It is also possible to use another transducer (e.g., another voice coil or other transducer) to offset the first component relative to the second component in the in-scan dimension. In a first technique, the in-scan position error can be measured and used to offset individual nozzle firings (i.e., as the printhead and substrate move relative to each other to achieve nozzle firing at a precisely corrected intended in-scan position). For example, a delay in nozzle firing can be calculated and programmed into the printhead for each nozzle, and firing is then driven from a common trigger signal. In a second technique, a common nozzle trigger signal or a shared nozzle trigger signal can be generated as a function of the gripper position (and / or the position of the first component of the gripper) and can be corrected for errors such that the trigger signal is generated to simulate an error-free movement of the gripper. With regard to this optional extension, it has already been described that in one implementation, the correction technique can be applied to each of the gripper and print head transport paths and used in concert with a position feedback system for each transport path to provide precise positioning in the x and y axes and to ensure coordinate system orthogonality and precise position control within the printing system. In one such implementation, the gripper system has a linear encoder that provides position feedback, for example, by imaging a visible mark or "check mark" associated with that transport path. Such markings can be applied, for example, via an adhesive tape that marks "each micron" (or other regular distance measure) of advancement relative to the track or guide.This position feedback can optionally be used to correct the in-scan dimension advancement of the gripper (e.g., so that the gripper is inherently or transparently correctly positioned relative to the in-scan direction). In systems where such position feedback is applied to each transport path (e.g., such that a similar linear encoding system is also used for printhead in-scan positioning), transducer-based correction techniques can provide offsets orthogonal to the transport direction for each printhead and gripper to define a coordinate reference system and precisely control drop placement. These techniques, by themselves, do not necessarily inherently correct non-orthogonality between the transport axes (e.g., the x and y axes associated with the gripper and printhead transport systems, respectively). In some embodiments, therefore, additional techniques described herein can optionally be applied to correct the positioning of the light beam used to mark the desired transport path, or to otherwise control an error correction system to account for the non-orthogonality. When combined with optional techniques for fine adjustment and / or correction, these techniques help provide precise position control of all elements in the manufacturing system. The various advantages and synergies of these various techniques will be detailed below.

[0048] Considering the principles discussed thus far, light sources and detectors (depending on the implementation) and any associated optics can be used to induce and / or sense position deviations of the transported components. At least one transducer can be used to correct the transport path error by displacing what is being transported in a dimension orthogonal to the direction of transport in response to the detected deviations using both common mode and differential mode control, i.e., using feedback. In still further detailed embodiments, this type of control can be applied, for example, to the "y" axis motion of a first transport system and to the "x" axis motion of a second transport system, to correct the transport path error in two different transport paths using separate sets of transducers. In this way, correcting the two different transport paths helps to facilitate precise correction across deposition and / or processing parameters. For example, in the context of the split-axis printing system introduced above, correction of both the gripper / substrate path and the printhead path effectively normalizes the "print grid" (the coordinate reference system used to define where droplets will be printed), providing a system in which the system's understanding of the print grid coordinates is precisely correct and not undermined by errors in the mechanical system associated with transport. These techniques and the various combinations and permutations discussed herein (including documents incorporated by reference) help provide precise positional control over the deposited droplets. For example, these techniques can be further applied to "z-axis" (e.g., elevation) or other dimensional motion control. Alternatively, the techniques described herein can be combined with the use of per-nozzle droplet and / or nozzle parameters to provide highly accurate control over the deposited liquid volume, as described, for example, in U.S. Pat. No. 9,352,561 and U.S. Publication No. 20150298153.

[0049] This disclosure will be broadly organized as follows: (1) Figures 1-3E will be used to provide an introduction regarding depositing material on a substrate, sources of fine alignment errors, and associated remedial measures. (2) Figures 4A-5 will be used to introduce more specific techniques, i.e., regarding online and offline processes for measuring / detecting and combating errors in the considered split-axis printing environment. (3) Figures 6A-6E will be used to explain specific mechanical structures in one or more detailed embodiments. (4) Figures 7A-H will be used to discuss various use cases and optional extensions. (5) Figures 8A and 8B will be used to discuss multi-dimensional control of the transport system components (e.g., x- and z-axis control).

[0050] Before proceeding with the introduction, it may be useful to first introduce certain terminology that will be used herein.

[0051] A specifically contemplated implementation may include an apparatus comprising instructions stored on a non-transitory machine-readable medium. Such instruction logic may be written or designed in a manner having a certain structure (architectural features) to cause one or more general-purpose machines (e.g., processors, computers, or other machines) to behave as special-purpose machines, each having a structure that necessarily performs a task described on input operands depending on the instructions, which when ultimately executed, take a specific action or otherwise produce a specific output. As used herein, a "non-transitory" machine-readable or processor-accessible "medium" or "storage device" refers to any tangible (i.e., physical) storage medium from which instructions may subsequently be read by a machine, including, for example, but not limited to, random access memory, hard disk memory, optical memory, floppy disks, CDs, solid-state drives (SSDs), server storage devices, volatile memory, non-volatile memory, and other tangible mechanisms, regardless of the technology used to store data on the medium. The medium or storage device can be in a stand-alone form (e.g., a program disk or solid-state device) or can be embodied as part of a larger organization, such as a laptop computer, a handheld device, a server, a network, a printer, or other set of one or more devices. The instructions can be implemented in different forms, such as as metadata that is effective to invoke an action when invoked, as Java code or script, as code written in a specific programming language (e.g., as C++ code), as a processor-specific instruction set, or in some other form. The instructions can also be executed by the same processor or different processors or processor cores, depending on the embodiment. Throughout this disclosure, various processes will be described, any of which may be implemented as instructions stored on a generally non-transitory machine-readable medium, any of which may be used to fabricate a product.Depending on the product design, such products can be processed to be in a sealable form or as a preliminary step for other printing, curing, manufacturing, or other processing steps that will ultimately create a finished product for sale, distribution, export, or import, where these products incorporate the engineered layers. Also, depending on the implementation, the instructions can be executed by a single computer, or in other cases can be stored and / or executed on a distributed basis, for example, using one or more servers, web clients, or application-specific devices. Each of the functions described with reference to the various figures herein can be implemented as part of a composite program or as a stand-alone module, both stored either on a single media representation (e.g., a single floppy disk) or on multiple separate storage devices. The same applies to the error correction information generated according to the process described herein, i.e., templates representing position errors as a function of transport path position, can be stored on a non-transitory machine-readable medium for temporary or permanent use, either on the same machine or for use on one or more other machines. For example, such data can be generated using a first machine and then stored for transfer to a printer or manufacturing device, e.g., for downloading via the Internet (or another network), or for manual transport (e.g., via a transport medium such as a DVD or SSD) for use on another machine. A "raster" or "scan path" as used herein refers to the progression of the print head or camera motion relative to the substrate, i.e., it need not be linear or continuous in all embodiments. The terms "hardening," "solidifying," "processing," and / or "rendering" a layer refer to a process applied to deposited ink to transform it from a fluid form into the permanent structure of what is being made. These terms are relative terms, e.g., the term "hardened" does not necessarily require that the completed layer be objectively "hard," so long as the completed form is "harder" than the liquid ink deposited by the printer.The term "permanent," as in "permanent layer," refers to something that is intended for indefinite use (e.g., as opposed to a manufacturing mask layer that is typically removed as part of the manufacturing process). Throughout this disclosure, various processes are described, any of which may be implemented as instruction logic (e.g., as instructions stored on a non-transitory machine-readable medium or other software logic), as hardware logic, or as a combination of these, depending on the embodiment or specific design. A "module," as used herein, refers to a structure dedicated to a specific function, e.g., a "first module" that performs a first specific function and a "second module" that performs a second specific function, refer to mutually exclusive code sets when used in the context of instructions (e.g., computer code). When used in the context of a mechanical or electromechanical structure (e.g., a "cryptography module"), the term "module" refers to a dedicated set of components, which may include hardware and / or software. In all cases, the term "module" is used to refer to a specific structure for performing a function or operation that would be understood by one of ordinary skill in the art to which the subject matter pertains, not as a general placeholder or "means" or "whatever structure" (e.g., a "team of bulls") to perform a described function, but as a conventional structure used in the specific technical field (e.g., a software module or a hardware module). "Electronic," when used to refer to a method of communication, can also include audible, optical, or other communication functions, e.g., in one embodiment, electronic transmission can encompass optical transmission of information (e.g., via an imaged 2D barcode) that is digitized by a camera or sensor array, converted to an electronic digital signal, and then exchanged electronically. The terms "transducer" and / or "actuator" are generally used in a synonymous manner and regardless of the form or type of transducer or actuator. For example, a "voice coil" and a "piezoelectric transducer" are each examples of an actuator / transducer.

[0052] Also referred to herein are detection mechanisms and alignment marks or fiducials recognized on each substrate, or as part of the printer platen or transport path, or as part of the printhead. In many embodiments, the detection mechanism is an optical detection mechanism that uses a sensor array (e.g., a camera) to detect a recognizable shape or pattern on the substrate (and / or on a physical structure within the printer). Other embodiments do not assume a sensor array, for example, a line sensor can be used to sense the fiducials as the substrate is loaded into or advanced through the printer. Note that some embodiments rely on dedicated patterns (e.g., special alignment marks), while other embodiments rely on recognizable optical features (including the geometry of any pre-deposited layers on the substrate or physical features in the printer or printhead), each of which is a "fiducial." In addition to using visible light, when referring generally to "light," "optical system," or "optics," alternative embodiments can rely on ultraviolet or other non-visible light, magnetic, radio frequency, or other forms of electromagnetic radiation. Also, it should be noted that some embodiments herein will be discussed with reference to a printhead, multiple printheads, or a printhead assembly, but it should be understood that the printing systems described herein may generally be used with one or more printheads. In one contemplated application, for example, an industrial printer features three printhead assemblies, each assembly having three separate printheads with a mechanical mounting system that allows positional and / or rotational adjustments such that the constituent printheads (e.g., of the printhead assembly) and / or printhead assemblies can be individually precisely aligned to a desired grid system. Various other terms will be defined below or used in a manner clear from the context.

[0053] I. Introduction 1, 2A-2B, and 3A-3E are used to introduce some of the techniques discussed in this disclosure and some of the problems that these techniques address.

[0054] More specifically, FIG. 1 depicts a prior art process 101 associated with a type of transport mechanism. In this specific example, it is assumed that there is a substrate 103 that is to be printed with droplets deposited at selected nodes of a printing grid 105. The printing grid 105 is illustrated as being centered within the substrate to represent that in this position, droplets of ink from the printhead are intended to land at precise locations (i.e., at locations represented by the nodes of the printing grid) with a predictability that translates to layer uniformity. However, it should be noted that while illustrated in this manner, the printing grid is defined relative to the printer (and not specifically the substrate) and extends to any location where printing may occur (e.g., the printable area may be larger than the substrate, and errors in substrate position may potentially translate to errors in droplet landing locations). Also, it is believed that the spacing of the vertical and horizontal lines is generally predictably spaced, however, this is typically based on the assumption that advancement along the x and y transport paths is precisely accurate (and / or linear). Finally, and while a printer, substrate, and printed grid are illustrated herein, it should be noted that these problems are not specific to printers, and the techniques described herein may be applied to a wide variety of situations in which something is mechanically transported, rotated, or moved. The context of printing processes, substrates, and printed grids is used as a non-limiting illustrative example to introduce the problems and techniques described in this disclosure.

[0055] Printing occurs as the substrate is transported, generally as represented by arrow 104, and a transport system mechanism is assumed to guide the substrate along a transport path 107. This transport path is illustrated in FIG. 1 as being slightly curved, which in this example represents mechanical imperfections in the transport system (e.g., of some type of edge guide, track or traveler, or other means used to steer the substrate 103). Note that in a typical industrial printing process, such as for making OLED display panels as described above, the substrate may be approximately 2 meters by 3 meters in size, while the nonlinearity of the path 107 may be a few microns or even smaller. The curvature (or other errors) of the path 107 as depicted in FIG. 1 is therefore exaggerated for purposes of discussion and illustration. While errors of this magnitude are not significant in many applications, in certain manufacturing processes (e.g., the manufacture of OLED displays and / or certain other electronic devices on large substrates), errors of this type may limit the achievable product size, lifetime, or quality. That is, the droplets generally need to be deposited at precise locations so that they mix together and produce a homogenous layer without leaving gaps or pinholes. Upon landing, the droplets spread only to a limited extent, and surface irregularities in the finished layer can limit the achievable layer thinness and otherwise create quality issues. Even slight mislocation of the droplet landing site can affect product quality and / or manufacturing reliability.

[0056] FIG. 1 as a diagram is conceptually divided into two halves, including a left half and a right half. The left half of the diagram shows a substrate 103 and a slightly curved transport path 107. The substrate 103 is generally advanced back and forth along this path 107 in what is designated the "y" dimension, as referenced by arrow 104. The numeral 103 represents that the substrate is at some point in proper alignment with a printing grid 105. The printing grid as depicted in this diagram is an abstraction in which the vertical lines represent the apparent paths of the individual nozzles of the printhead as the printhead and substrate are moved relative to one another, while the horizontal lines represent digital firing signals or other capabilities of the nozzles to refill and fire repeated drops of ink (i.e., the spacing of these horizontal lines typically represents the "speed" at which the nozzles can fire). Alternatively, described differently, the printing grid 105 has nodes, each of which represents an opportunity to fire a drop of ink. As already indicated, it is desirable to deposit the ink in a manner that is precisely controlled in terms of position and leaves no pinholes, which is achieved in part by having precise knowledge of where each droplet will land on the substrate. It is further noted that the droplets are deposited at discrete locations, but are viscous and therefore typically spread out to form a continuous liquid coat that has no gaps or irregularities. The volume per unit area is generally pre-correlated with the desired thickness or other properties of the final layer, and thus the droplet density and relative position can in theory be selected (taking into account the expected droplet size) in a manner that promotes a uniform layer of the desired thickness after droplet spreading and mixing to produce the desired effect (this is discussed in U.S. Pat. No. 8,995,022, which is incorporated by reference).

[0057] The printing grid 105 is depicted diagrammatically in the left half of the figure in a "squared up" fashion with the substrate 103, representing where printing will generally occur at the desired drop landing locations.

[0058] Unfortunately, errors (i.e. curvature) in the transport path 107 can effectively distort the printing grid 105, meaning that droplets do not always land where they are supposed to be relative to the substrate, as they are subject to minute positional and rotational errors as the substrate is advanced. The right hand side of FIG. 1 illustrates the substrate translation and / or orientation errors as the substrate is advanced from a first position d0 along the transport path 107, with the substrate position and yaw represented by 103′ relative to a (virtual) ideal “reference edge” 109, to a second position d1 along the transport path, with the substrate position and yaw represented by 103″ relative to the reference edge 109. As can be seen, the substrate is subject to offset and rotational errors in multiple dimensions due to errors (e.g. curvature) of the transport path 107. The errors can be seen in this example to be horizontal and vertical offsets Δx0 and Δy0, and an angular offset Δθ0 in the xy plane when the substrate is moved to the first position d0, and different horizontal and vertical offsets Δx1 and Δy1, and an angular offset Δθ1 when the substrate is advanced to the second transport path position d1. As the nature of these errors changes as the substrate is advanced, these errors may be measured in a number of dimensions, e.g. The effect of the described type of error is to distort the printing grid, which means that the planned printing process (in theory) produces the desired layer properties, but in practice the drop deposition may be distorted, potentially resulting in quality issues. If left uncorrected, these various errors may produce pinholes, thin zones, and other defects that limit the precision and / or quality achievable with the printing system. Again, this may limit device size (e.g., it may be difficult or impossible to produce products with better quality or resolution, such as high quality miniaturized products or very thin large area display screens). The effect of the described type of error is to distort the printing grid. For example, the system and printing plan may effectively assume a straight printing grid (105 in FIG. 1), while "y" errors and / or jitter (i.e., parallel to the transport path) effectively distort the separation between the horizontal lines of that printing grid. Similarly, "x" dimension errors and / or jitter effectively distort the separation between the vertical lines of that printing grid, the result being errors in the deposition locations of the individual drops.These types of errors can result in too little or too much fluid deposition or other non-uniformities in various pixel wells, potentially leading to brightness and / or hue variations or other errors in the finished display; in the context of "macroscopic layers," such as encapsulation errors spanning many electronic components, these types of errors can lead to non-uniformities in the layer, potentially impairing layer function.

[0059] As illustrated in this example, it should be noted that the depicted errors may in some cases simply be a repeatable function of the transport path 107, i.e., there is a nonlinear displacement in the x dimension, a nonlinear displacement in the y dimension, and a nonlinear tilt, as the transport path is considered as curved in this example. Other types of errors, such as z-dimension errors, pitch, and roll, may also potentially occur on a repeatable basis, but are not depicted in this particular figure. Thus, in applications such as industrial printers used to create fine (e.g., micron or smaller scale) electronic, optical, or other structures that rely on uniformity of the type described, the same errors may potentially occur from substrate to substrate if a series of substrates are to be printed as part of an "assembly line" type fabrication process. There are also other potential sources of error that may be specific to a given substrate and / or may represent changing conditions, e.g., temperature fluctuations.

[0060] Although errors affecting substrate progression are illustrated, there are other sources of similar errors that can potentially affect device quality and / or process reliability. For example, split-axis printers typically move not only the substrate, but also printheads or cameras, or other mechanical components. Briefly, in systems that move one or more printheads (generally in the "x" dimension relative to FIG. 1), similar path errors can result in "x", "y" rotations or other errors in the printheads (relative to the dimensions of FIG. 1). For example, if the printheads have errors in different positions, such also typically have the effect of distorting the vertical lines of the printing grid 105 (i.e., spacing them unevenly). Similar analogies can be drawn with respect to other transport path analogies in industrial printing systems of the referenced type. In general, it is desirable to reduce the effects of these layers and improve predictability and reliability in layer processing, and generally have the ability to process thinner, more homogenous layers.

[0061] To address these issues, an embodiment provides a transport path correction system that detects and neutralizes one or more forms of path errors. Figure 2A shows an embodiment 201 having two main components, including a first track-guided component 203 and a second offsettable component 205. Both of these components generally move together in a general direction represented by arrow 206. In one implementation, these two components can be part of a vacuum gripper that is used to engage and move a substrate along a "fast" axis. In another implementation, these two components can instead be part of a printhead traveler, for example, that travels a track and carries a printhead for use in printing droplets on a substrate.

[0062] The depicted embodiment uses a light source 207 that directs a beam of light 202 in a manner that will serve to guide or promote the desired travel, in this case a perfectly straight travel simulating a "virtual edge guide". In the depicted scheme, the light source 207 is stationary and the beam 202 it emits is sensed by two optical detectors 208 and 209, both mounted on the second component. In addition, beam splitters 211 and 212 are used to redirect light from the optical path to the detectors 208 / 209 in a manner that will be used to sense and correct deviations of the second component from the optical path. It should be noted that the depicted structure is not required for all embodiments, for example, a specifically contemplated variant features a light source mounted on the second component with one or more beam splitters and / or one or more detectors stationary, although other configurations are possible and will occur to those skilled in the art.

[0063] To correct for path deviations, the signals from each of the detectors are optionally fed to a processing circuit 214 / 215 that applies a function "F" to these signals to generate correction signals that will be applied as feedback to correct the path deviation. Although two sets of such circuits are depicted, it is possible to use only one circuit (e.g., a software-driven processor) or to have significant duplication of circuit elements. The correction signals are then fed to one or more transducers "T" that instantly apply a correction to "zero" the deviation from the optical path, i.e., advantageously, the processing circuit and / or the detector generate a signal that is "zero" (or does not cause further transducer adjustments) when the second component 205 is synchronized with the optical path, and that drives it back to zero whenever there is a deviation from the optical path. It should be noted that this structure is not required for all embodiments. In the figure, it can be seen that the depicted embodiment relies on two transducers, specifically numbered 216 and 217, each of which provides a substantially linear throw in a direction perpendicular to the direction of transport. In this example, the use of two transducers at separate points of interaction (c1 / c2) between components 203 and 205 provides common mode and differential mode control, respectively, to linearly offset component 205 from the first component 203 (in the direction of arrow 213) and to provide rotation of component 205 relative to component 203 as represented by the angular measure "θ". The transducers can be any desired type of transducer suitable for the throw in question, including but not limited to piezoelectric transducers. In embodiments in which the substrate is supported by an air bearing (and component 205 uses a vacuum gripper to engage the substrate), the transducers can be voice coils, advantageously providing a relatively large maximum throw (e.g., sub-micron to 100 microns or more) with a high degree of repeatability and reliability.The combination of common mode and differential mode control for the transducer essentially provides a floating pivot point between components 203 and 205 that can be offset in the "x" direction (note that the xyz coordinate labels seen in the figures are arbitrary in this example). To help provide mechanical structural support between components 203 and 205, in some embodiments, a mechanical linkage ("M") 218 ​​can be used that constrains components 203 and 205 to move with one another in the "y" direction, while at the same time allowing free offset and relative xy rotation between these components in the "x" direction. Such additional structural linkage can be particularly advantageous when a voice coil is used as the transducer, to help constrain any unwanted loads on the transducer in a direction orthogonal to the direction of transducer displacement. Numeral 221 provides additional details regarding the detector, showing a two-cell design, where the cells are represented by values ​​"a" and "b". Briefly, in one design, light from a light source impinges on one or both of these sensors, and the difference between the voltages generated by each of these sensors is used to linearize the second component 205 with respect to the optical path. For example, in a two-cell design, the value "(ab) / (a+b)" generates positive and negative outputs proportional to the amount of deviation from the midpoint of the two cells. Such a signal can be used alone to drive a transducer associated with the position where the optical path is centered between the two cells. Note that in some embodiments, the processing circuitry 214 / 215 can be combined with the detector and purchased as a single unit that provides, for example, a digital or analog output representative of the imbalance signal sensed by each cell of the detector.

[0064] In some embodiments, it is possible to sense path deviations in more than one dimension, for example, in each of the x and z dimensions relative to the depicted coordinate system. For this detection of deviations, a four-cell design can be used, represented by the numeral 223 in the figure. For example, the value "[(a+c)-(b+d)] / (a+b+c+d)]" can be used to sense x-dimension deviations from the desired path, and the value [(a+b)-(c+d)] / (a+b+c+d)] can be used to sense z-dimension deviations from the desired path. Note that to correct deviation motions in the second (or third, fourth, etc.) degree of freedom, depending on the implementation, a separate second set of correction transducers (not seen in this figure) may be required. The transducer configuration is similar to that already depicted in FIG. 2A, except that the direction of transducer displacement can be, for example, along the z dimension. It should be noted that the use of a linear transformer is not required for all embodiments; rather, corrections can be made with respect to one or more rotational degrees of freedom, for example to even out surfaces or edges, and to correct pitch, yaw, and / or roll.

[0065] FIG. 2A also illustrates some additional optional components that may be used in some embodiments. First, numeral 225 refers to an adjustment mechanism that can be used to align and / or adjust the light source 207. In one embodiment, the light source is a laser, and numeral 225 refers to a screw-based precision mount that changes the attitude and / or yaw of the laser relative to the direction of transport. Second, numerals 227 / 229 refer to beam splitters and detectors that can be used for the same purpose; for example, by mounting such detectors in a fixed manner relative to the light source 207, the light source can be periodically recalibrated (e.g., adjusted using adjustment mechanism 225) to ensure proper orientation. It is also possible to use a standard 231 at the far end of the optical path to aid in alignment and / or automatically provide feedback regarding the proper orientation of the light source. In one embodiment, the standard can be a simple target or line of sight (e.g., the laser is adjusted until its beam hits the center), while in another embodiment, the standard can be a detector / circuit that provides electronic feedback, for example, allowing manual or automatic alignment of the light source.

[0066] FIG. 2B is a flow chart depicting a method step 251 that implements some of the techniques introduced above. As represented by numeral 252, the method can be embodied in a manufacturing system having a transport path where it is desired to correct fine motion, position, or orientation errors of the transport system. For example, the manufacturing system can perform high-precision product "assembly line" manufacturing using a printer for material deposition, as introduced above. First, an alignment or calibration step 253 can be performed to ensure that the light beam is accurately directed as desired to mark a linear progression. For example, as introduced above, the light beam can be used to image a stationary target with a line of sight, and can be adjusted 254 either manually by a human operator or automatically based on electronic feedback until the light beam is incident with a reticle formed by the line of sight. In a typical implementation, calibration can be performed upon initial installation, at start-up, periodically (e.g., daily or weekly), upon the occurrence of some milestone event (e.g., a detected error above a threshold, or a temperature change above a threshold amount), or as otherwise desired. A series of substrates 255 are then introduced in succession and aligned with the printer's coordinate reference system to ensure that the individual panel products on these substrates are in a known position relative to the light beam (e.g., as formed by a properly aligned laser). This process will be discussed further below, but in one embodiment, the combination of optical alignment marks per transport path (e.g., position feedback for the gripper and printhead) and two transducer-based error offset systems and associated optical paths effectively defines a coordinate reference system for the printer and coordinates motion in that coordinate reference system. Each given substrate in the series can be individually aligned to this coordinate reference system by imaging fiducials on the given substrate and adjusting either the substrate position / orientation or the printing recipe so that printing occurs precisely on each panel as desired. Printing then occurs on the aligned substrate.As each conveying or transport system is operated, the error (i.e., deviation from each marked optical path) is dynamically measured, by numeral 255, optionally for more than one transport path and / or one dimension per transport path, as indicated by numeral 257, and optionally using one error correction system to correct for multi-dimensional errors (e.g., x and z deviations using a four-cell detector design), by numeral 258. Dynamic correction 259 is then applied as feedback to instantly correct the error and to change the position and orientation of the "second component" relative to the first component to drive the deviation from the associated optical path to zero, i.e., so that the "thing" being transported (e.g., substrate, camera, print head, or other element) travels the desired perfectly straight path despite microscopic jitter that may still affect the transport system. As mentioned above, in one embodiment, alignment along the direction of transport (e.g., in a direction parallel to the light beam used as a guide) can be optionally assisted through the use of an alignment system, for example measuring marks on an adhesive tape proximate to the transport path, for example with alignment marks every micron of progression along the transport path. A transducer-based correction system in such an embodiment is therefore relied upon to correct path deviations and rotational deviations in a direction perpendicular to the marked optical path direction (for example, optionally using two or more transducers, per numeral 265, and differential mode control for two or more transducers, per numeral 267). The result is that what is being transported follows a virtual ideal path as already referred to and identified by numeral 269.

[0067] Having introduced transducer-based correction and the use of optical guidance, its application to path error control will now be discussed, again in the exemplary context of an industrial split-axis printer environment.

[0068] FIG. 3A shows an embodiment 301 for reducing transport path errors in a gripper system advancing a substrate, such as substrate 103 from FIG. 1. More specifically, it is again assumed that the substrate is advanced back and forth along a path represented by arrow 104. In this example, the substrate will be advanced using a gripper. A first component 302 of the gripper will generally travel along path 107 (from FIG. 1) along a track extending in the "y" dimension. The gripper also has two transducers (T) 305 and 306 that operably connect the first component 302 with a second component 303 that engages the edge of the substrate. In one exemplary case, the substrate is supported on air bearings above a floating table to provide a nearly frictionless support, while in other examples other mechanisms can be used for support and transport. Each of the two transducers is controlled to displace the second component relative to the first component along a common direction (e.g., in the "x" dimension as illustrated in the figure), as represented by arrow 310. Each transducer can be controlled independently, leading to a situation where "common mode" control linearly offsets the second component in the x dimension toward and away from the first component 302 at the respective engagement points, while "differential mode" control pivots the second component relative to the first component about a pivot point "Xpvt". It can be seen that the pivot point "Xpvt" is a floating pivot point because the transducers can be electronically driven in a manner that has both common and differential drive components. In some embodiments, this floating pivot point can be an abstract concept, while in other embodiments, a mechanical structure provides the pivot while also providing a structural coupling between the two components of the gripper. It should be noted that although this figure shows the gripper as engaging the substrate near its upper left corner, in typical circumstances it may be desirable for the gripper to engage the substrate midway along its length, for example to provide a mutual moment of the transducers (e.g., to facilitate control over both common mode and differential mode displacements).

[0069] While the first component 302 follows the error-disturbed path 107 from FIG. 1, the second component latches onto what is being transported (in this case substrate 103, e.g., using a vacuum) and is dynamically offset to follow a linear path. Transducers 305 and 306 are found to be independently controllable to move the substrate, as shown by arrows 308 and 309, and are controlled in such a manner as to precisely nullify x-dimensional and θ-rotation-induced errors in path 107, such that the substrate motion follows an ideal "reference edge" (see line 109 from FIG. 1). Note that in an alternative design, instead of having linear throws that are parallel to each other, transducer 305 could achieve the rotation while transducer 306 could achieve a linear throw, or the transducers could be made to generate an offset in the "y" dimension or any other desired dimension, with the corresponding effect of mitigating errors in the position or rotation of the substrate. 3A, the gripper first component 302 moves along the "y" dimension while transducers 305 and 306 each push and pull the substrate along a linear range of motion along the "x" dimension via contact at respective contact points "c." Again, each transducer, in this example, can be a linear motor, a piezoelectric transducer, a voice coil, or another type of transducer.

[0070] In the split-axis printing system of this example, the substrate is advanced in the "y" dimension relative to the printhead for a particular "scan" or raster motion. The "y" dimension in this example therefore also forms the "in-scan" dimension. The printhead is then moved in the "x" dimension (i.e., in the "cross-scan" dimension) to reposition the printhead for the subsequent scan, and the substrate is then advanced in the opposite direction for the subsequent scan, with successive scans continuing until the entire liquid coat has been created. The substrate can then be advanced (typically out of the printer to another chamber) and the liquid coat cured, dried, or otherwise processed to convert the liquid coat into a permanent structure having the desired electrical, optical, and / or mechanical properties. The printing system is then ready to receive another substrate and perform similar printing on the subsequent substrate, for example according to a general pre-defined "recipe."

[0071] It has already been mentioned that errors along the transport path 107 (from FIG. 1) can potentially lead to errors in multiple dimensions (i.e. not just offsets in the x dimension). This may be less significant if the transport system is aligned in position (e.g. using registration marks as already referenced), but in other systems, variations in the angle of the path may also lead to non-linearities in the y position of the substrate. In such implementations, the y dimension errors can optionally be corrected using other forms of means 311 for correcting the substrate motion in the "in-scan" dimension. Options include, for example, using a third transducer 314 to effect a throw of the first and / or second components of the gripper in the in-scan dimension to normalize the y dimension advancement of the substrate. In other embodiments, feedback can instead be used to adjust electronic control signals 315 (e.g., as feedback signals, delta signals, or electronic drive signals) for gripper advancement to impart a slight velocity increase or decrease (Δv) to counter y-dimension errors, or gripper motion can be triggered to match position markers as introduced above. In yet another optional embodiment, adjustments can also be implemented in software, for example by calculating and programming individual y-position dependent nozzle firing delays (as represented by box 316), i.e., nozzles of the print head can be "commanded" to print slightly earlier or later as the substrate and print head are moved relative to each other in the "y" dimension in a manner that, in some embodiments, exactly counters "y"-dimension position errors of the substrate relative to the printer. Also, per numeral 317, in another embodiment, the "trigger" signals used to time nozzle firing can be adjusted to have the effect of shifting the horizontal lines of the printing grid (see numeral 105 from FIG. 1) to counter position errors of the substrate relative to the printer. Note that gripper "in-scan" or "y-axis" compensation is not required for all embodiments.

[0072] FIG. 3A also shows the optical system used to define the desired progression. As already introduced, a light beam 318 is directed from a light source 319 (e.g., a laser) in the progression direction (e.g., in this case parallel to the y dimension as referred to in the figure). At least one sensor or detector 320 is used to image this path and detect deviations from the light beam 318 as the gripper and the substrate move along their transport path. Advantageously, the at least one sensor or detector 320 is mounted in a fixed manner on the second component 303 of the gripper, such that a feedback signal derived from the sensor or detector 320 is used to reorient and displace the substrate in the x dimension and xy orientation as the progression occurs, such that the substrate movement corresponds exactly to the marked optical path (318), even though the movement of the first component of the gripper continues to be subject to mechanical jitter. As mentioned above, in contemplated variations, the light source 319 and sensor / detector 320 can be configured differently, such as with the light source 319 mounted on the second component 303 of the gripper, using beam splitter optics mounted on the gripper, etc. Such design variations are well within the skill of one of ordinary skill in the art of optics.

[0073] 3A, it should be observed that the use of two or more transducers in a mechanical transport system can correct errors in the transport path (e.g., with respect to nonlinear guides or tracks or edges) or other motion errors. While a path error may exist as represented by numeral 107 in FIG. 1, the techniques and structures introduced above attempt to "coexist" with this repeatable error in the transport path (e.g., the first component 302 of the gripper continues to travel a path disturbed by this error), but the transducers achieve a throw or other correction to equalize and / or nullify this path error in at least one dimension, so that what is being moved (in this example, the substrate) travels an idealized path as represented by numeral 109 in FIG. 1. In one embodiment, these motion corrections can be achieved mechanically by two or more transducers (e.g., transducers 305 and 306, each independently controllable with a linear throw in a direction (e.g., 310) substantially orthogonal to the direction of arrow 104) that are parallel to each other and each have a linear throw substantially orthogonal to the direction of conveyance.

[0074] Although these techniques can be applied to virtually any mechanical transport system, one area that may benefit from these techniques has already been described as being related to industrial printers, where ink droplets need to be deposited at very precise locations. For example, one considered embodiment is as a printer used to fabricate light-emitting devices such as organic LED display devices (e.g., cell phone screens, HDTV screens, and other types of displays), and "panel" devices such as solar panels. In this regard, in the applications discussed above (e.g., on which meter-wide and long substrates are printed), some conventional systems rely on air-floating tables to advance the substrate during printing. Gas ingress and egress in such systems can be carefully controlled to avoid imparting effects to the substrate (e.g., temperature, static electricity buildup, or other effects that may affect the ink behavior) that could potentially cause defects in the finished layer. In other words, gas flow is used to generate a fluid bearing under the substrate, creating a substantially frictionless surface along which the substrate is moved during printing. The second component 303 from FIG. 3A in such applications can support a vacuum chuck that engages the substrate, or multiple vacuum locks that engage individual parts of the substrate. In such applications, to achieve the “micron-scale” (or smaller) throw used to neutralize nonlinearities and provide precise path advancement, the transducers 305 and 306 can advantageously be formed as voice coils that use compression and expansion (i.e., normal to the direction of the force supported by the floating table's gas bearings) to achieve the microscopic throw used to achieve precise printhead and nozzle alignment with the substrate. That is, with respect to electronic flat panel processing specifically, and with respect to OLED display device processing specifically, the use of (frictionless) floating supports and vacuum grippers is important to minimize defects and maximize device lifetime, and the use of voice coils as transducers has been found to provide an effective component for providing the required throw in such systems.However, other types of transducers may also be used to achieve the throw for a particular type of application, for example through the use of a piezoelectric transducer, a linear motor, or other type of transducer. In such systems, a floating mechanical pivot mechanism may optionally be used to assist the voice coil in providing structural linkage and mechanical support for error correction.

[0075] FIG. 3B provides a diagram 321 similar to that of FIG. 1, but further illustrates a goal that can be reached using the mechanism of FIG. 3A. More specifically, FIG. 3B shows the substrate 103 and gripper from FIG. 3A as they advance along a path 107. As in FIG. 1, the path 107 is again assumed to have errors that exhibit some form of curvature or variation, which again may be errors in edge guides, tracks, or other mechanisms, which impart position and / or rotational errors to the gripper. However, in this case, the gripper is considered to have a transducer "T" that is controlled to counteract this error, for example in the form of a voice coil displacement that compensates for or equalizes the variation of the path 107. Again, it should be noted that the scale of the errors is greatly exaggerated relative to the scale of FIG. 3B, for example, in practice the path may be meters long (e.g., a 3 meter long substrate is transported through a room-sized printer), while the curvature may be micron or sub-micron in scale.

[0076] It will be recalled from FIG. 1 that at the gripper's position d0 along the path, the original transport path errors were equal to Δx0, Δy0, and Δθ0. However, with respect to the system of FIG. 3B, the transducer is actuated to displace and / or rotate the substrate as seen on the lower right side of FIG. 3B and designated by numeral 103′. That is, the transducer “T” displaces the gripper's second component and the substrate relative to the gripper's first component and track or edge guide 107 to have absolute positions x3, y3, and θ3. In the context of 3B, the quantity x3 represents an absolute x position that effectively defines a virtual edge 323 offset from the error-disturbed transport path 107, the quantity y3 corresponds to an optional positioning offset of the substrate that offsets it to an arbitrary “smoothed” or normalized advance (330) relative to the in-scan (or transport) direction, and the quantity θ3 corresponds to a desired angular orientation of the substrate. With respect to the example of FIG. 3B, for the moment it can be assumed that y3 and θ3 are "zero", e.g. the substrate is oriented to be exactly vertical (i.e. squared off relative to the floating support table with no "y" dimension correction, although this need not be the case in all embodiments). In FIG. 3B the printing grating is depicted in numeral 105' to have a consistent x and θ relationship to the substrate 103'. As the substrate is advanced from position d0 to position d1, the transducers are controlled to maintain this consistent positional relationship between the substrate and the normal of the printing grating, i.e. the substrate is aligned to have absolute positions x3 and θ3 (notwithstanding errors along path 107) and is therefore depicted in 103" as having exactly this relationship to the printing grating in 105". It should be noted that in these examples the printing grid is illustrated as maintaining a predetermined relationship to the substrate, however the printing grid is defined by the printhead positioning and substrate and printhead transport system, and what is truly desired is for the printhead and substrate transport mechanisms to maintain a consistent, predetermined relationship to each other, and for the coordinate system established by this linkage to be precisely aligned for each product being processed.In some embodiments, the printer coordinate reference system is first calibrated (and adjusted) to effectively define the printing grid, and each substrate (or product being processed thereon) is then specifically aligned to the printing grid as it is introduced (i.e., into the printer) via a product-by-product or substrate-by-substrate alignment process. This will be illustrated further below.

[0077] Equations are depicted at various locations in the figure to show how constant positional relationships are maintained. More specifically, it will be recalled that the inherent repeatable errors of the transport path 107 at position d0 were equal to the position and rotation offsets of Δx0, Δy0, and Δθ0. The converter "T" is therefore controlled to add further offsets of Δx2, Δy2, and Δθ2, which are applied in response to the detected errors at position d0 along the transport path. That is, in one embodiment, these values ​​are the negatives of the errors Δx0, Δy0, and Δθ0, i.e., they exactly cancel the errors and optionally offset the substrate to some pre-determined x / y / θ value. In one embodiment, the converter "T" depicted only corrects the substrate position in x and θ (e.g., any "y" dimension correction is optionally achieved using a position feedback / adjustment system as described above). Note how at position d1, the converters are controlled to add different offsets depending on different errors in position on the transport path 107, i.e., adding offsets of Δx4, Δy4, and Δθ4. As depicted in FIG. 3B, the values ​​x5 and θ5 can be exactly equal to the values ​​x3 and θ3, but again, this need not be the case in all embodiments.

[0078] Micron-scale or better position control is in many ways not as intuitive as it may seem; for example, in one embodiment, the gripper transport system and the printhead transport system each carry a camera that is used to find a common registration mark and thereby establish the origin of a coordinate system that matches the two transport paths. This process, and the transport systems for each printhead and substrate in such a system, effectively define the printer's coordinate reference system (and in large part determine the configuration of the printing grid according to which droplets can be deposited). U.S. Provisional Patent Application No. 62 / 459,402, already incorporated by reference, provides information regarding the use of these cameras, position detection, and associated calibration. Essentially, in addition to finding a common coordinate point (or "origin") in one disclosed system, each transport system uses optical tape and optical sensors to provide precise (e.g., micron-scale) position detection and feedback so that the transport system (e.g., the first component of the gripper) "knows" exactly where it is relative to the printer's coordinate system, and these various components work together to effectively define the complete printer coordinate system. In fact, use of such a system can eliminate the need for component offsets in the direction of transport; for example, a gripper is simply driven to a specific, appropriate position value in the direction of transport.

[0079] Once the "origin" is established by the referenced camera alignment process, the two transport systems are geared to determine the relative coordinates between each transport system camera and a transport system reference point (e.g., corresponding to a print head nozzle position), which then allows precise identification of any point relative to the printer's coordinate system, assuming a proper understanding of the relationship (e.g., orthogonality) between the coordinate axes. As mentioned above, in such a system, the printer's "understanding" of the drop landing location depends on the printing grid, which in turn is defined by this coordinate system. Transport path motion errors in such a system, if left uncorrected, can potentially lead to a situation where a particular printing grid location (e.g., associated with an understanding of a specific combined gripper / print head position) deviates from the actual positions of these components. By correcting the transport path errors in the manner described herein, using the various devices described herein, this allows the system to correct its path errors such that the substrate and print head are each positioned in a manner corresponding to the printing grid assumption. In fact, as described elsewhere herein, even errors such as minor non-orthogonality between the transport paths can be corrected using optional rotational offsets (e.g., non-zero values ​​of θ3 and θ5) and / or by adjusting the optical guides (e.g., light beams for one or more transport paths) to correct for the non-orthogonality in the transport paths, as described above.

[0080] Continuing with the example provided by Figure 3B, each substrate introduced into the system then has one or more fiducials identified and used to precisely understand the position of the substrate (or the panel product thereon) during printing. As each substrate is introduced, its fiducials can be detected (e.g., using one or more of the cameras) and a mechanical system can be used to properly orient / align the substrate to correspond to the expected position (note that this process is not necessary for all embodiments, e.g., it is also possible to adjust the printer control information by modifying the printing recipe and / or firing triggers or details to accommodate known substrate misalignment or angular orientation loss).

[0081] The bottom portion of FIG. 3B illustrates how two linear transducers (e.g., voice coils) on the gripper are driven to correct for rotational errors and to positionally offset the substrate in a manner that corresponds to an idealized edge (e.g., via displacement in the “x” dimension). More specifically, a local portion of the transport path is designated by numeral 327 as having a significant amount of curvature that deviates from the idealized straight edge 109 of the transport path. At two effective contact points between the substrate and the transport path (designated “c1” and “c2”, respectively), the errors are assumed to be “xi” (depicted as an offset relative to the idealized straight edge in the negative direction) and “xj” (depicted as an offset relative to the idealized straight edge in the positive direction), respectively. Here, it is assumed that it is desired to precisely position the left edge of the substrate (or printable area of ​​the substrate) at an absolute position “xk” from the idealized transport path (e.g., corresponding to the depicted virtual edge 323). Number 105' represents a slight offset of the printing grid to accommodate the full range of "x" positional errors imparted by the system, and optionally provide some slight buffer. To achieve this correction, the positive error (i.e., xi) at position "c1" is further offset by an amount "xk-|xi|", while the negative error (i.e., xj) at position "c2" is further offset by an amount "xk+|xj|". The two depicted transducers "T" are controlled for this purpose, thus straightening the substrate relative to an idealized straight edge. Similar corrections are performed at all other times during the movement of the gripper along the transport path 107 depending on the errors at the relevant positions, i.e. so that the substrate follows a virtual path associated with the absolute position "xk".

[0082] A few points should be noted with respect to this discussion. First, the gripper is depicted in this figure as a single unit, but in reality can be made up of many parts (e.g., the first and second components mentioned above, or a distributed series of two, three, five, or another number of grippers or gripper components that engage the substrate at different locations). Second, in this embodiment, two transducers are depicted as parallel linear actuators (e.g., voice coil or piezoelectric transducers, respectively), but this is not required for all embodiments. That is, depending on the embodiment, the transducer "T" can be coupled in series and can be a rotary, linear, or other type of actuator. In still other embodiments, more or less than two transducers can be used. Third, as mentioned above, various mechanisms exist for identifying the position along the transport path, for example, signals (e.g., drive signals, timing signals, etc.) can be used for this purpose, as represented by numeral 328, or a position sensor 329 (camera, etc.) can be used. In one specifically contemplated embodiment, as referenced above and discussed in U.S. Provisional Patent Application No. 62 / 459402, a position marking system and a position detector are used for each transport path to measure and / or adjust associated positions (e.g., for print head transport and substrate transport). Obviously, many alternatives are possible.

[0083] As already referenced, a processing device or system can have multiple transport paths. In the context of a split-axis printer, in one embodiment, as already referenced, the printer coordinate reference system can be defined depending on separate print head and substrate transport paths. FIG. 3C is used to discuss position errors resulting from inaccuracies in a second transport path, such as the print head transport path. Such a situation is generally depicted by numeral 351 in FIG. 3C. The substrate is advanced by the gripper in a first dimension (i.e., using one transport system, as represented by arrow 104), and the print head is advanced along a second transport path 356 in a second dimension (i.e., using another transport system, as represented by arrow 354). At a first position 353 of the print head along the transport path associated with the latter transport system, the print head is subject to errors Δi0, Δj0, and Δφ0. Note that the variables i, j, and φ represent the x and y offsets (and angular rotations in the xy plane), but i, j, and φ are used instead of x, y, and θ to distinguish this embodiment from that of the gripper transport system. As the print head is advanced to position 353′, as represented by phantom lines on the right side of the figure, the errors are Δi1, Δj1, and Δφ1. Again, this error is a function of position along the transport path 356, and the change in error is potentially linear or non-linear. If left uncorrected, this error can also distort the print and cause manufacturing accuracy problems as already referenced. In this embodiment, it is assumed that any motion of the substrate 103 relative to the gripper transport path is corrected using the depicted gripper (and its transducer “T”), but the problem is that the print head traveler can also generate errors, resulting in x, y, or θ errors of the print head, changing the expected landing position of the droplets ejected from the print head nozzles.The effects of these errors are illustrated relative to the intended printed grid 357, as shown by arrow 355; i.e., the effect of unintended printhead rotation (and / or unintended "x" dimension displacement) is seen through a distorted printed grid 257' (in a similar manner, unintended printhead rotation displacement in the "y" dimension would effectively result in "squeezing together" the vertical printed grid lines).

[0084] In relation to the figure, it is also desired that the print head undergoes ideal motion, i.e. motion that is not characterized by unintended mechanical errors. That is, in this example, it is also desired that the print head follow a hypothetical ideal (e.g., linear) transport path 325 that would effectively correspond to an unperturbed printing grid (e.g., represented by numeral 357). This is achieved in one embodiment by having the transported object (i.e., the print head) follow both a hypothetical "ideal" gripper motion represented by vertical line 109 and a hypothetical "ideal" print head motion represented by horizontal line 325.

[0085] In much the same manner as the gripper path correction, the transport system for the printhead transport path can also optionally use an optical guide (e.g., a laser source and associated optics / detection system) and a set of transducers to facilitate idealized printhead positioning. To this effect, in response to dynamically sensed errors, the transducers advantageously provide a displacement to an arbitrary "absolute" position that accommodates the entire range of printhead "y" position errors, optionally providing some slight buffer, so that the printhead motion corresponds to a virtual path 369, which also provides a fixed, known position that corresponds to the "offset" printing grid (105' from FIG. 3B).

[0086] FIG. 3D provides an illustration of a system 361 intended to correct for this type of error. That is, FIG. 3D shows a second transport path 356 used to support lateral movement of one or more printheads in the general direction indicated by arrow 354. The printhead assembly includes a first "track-guided" component 363 that rides (e.g., along a track or guide) along the transport path 356, and a second offsettable component 364 that mounts the printheads. These first and second components are again operatively coupled by one or more transducers 365. The transducers are, in this example, linear actuators that each support a micro-throw to offset the second component in the "y" dimension (and / or the "z" dimension), and common mode and differential mode drive are again used to selectively achieve linear displacement and / or xy plane rotation (θ). As represented by both numerals 367 and 367' (representing the printhead at distinct positions along the "cross-scan" or "x" dimension, respectively), the corrections allow the printhead to follow a virtual ideal path 369 that is not characterized by mechanical errors (i.e., even though the first component 363 continues to travel the error-impeded second transport path 356). A light source 370 is again positioned to direct a light beam 371 to detect and correct jitter in a dimension orthogonal to the direction of the light beam. Note that depending on the design (and size and / or available space on the printhead assembly), it may be desirable to have the light source mounted on the second component 364 to detect beam deviations relative to a stationary detector and / or optics (not shown) rather than detecting motion of the detector and / or optics relative to a stationary beam.As with the gripper embodiment, the transducers of FIG. 3D can be controlled to offset the printhead to an absolute y position (i.e., corresponding to line 369) such that when the printhead is at position 367, the aforementioned errors of Δi0, Δj0, and Δφ0 are further offset by Δi2, Δj2, and Δφ2, and when the printhead is at position 367′, the transducers are controlled to offset the printhead and add offsets Δi4, Δj4, and Δφ4. i and φ typically have constant values ​​at positions 367 and 367′, and are both typically zero, although again, this is not required for all embodiments. As with the previous gripper example, the depicted transducer configuration is merely exemplary and different transducers (e.g., rotary transducers) can be used and can be applied to different transport systems and / or dimensions. Additionally, as with the previous example, the depicted transducers offset the printhead in this embodiment using both common mode control and differential mode control to achieve a floating pivot point. The result is that the desired "error-free" transport path 325 is offset to an arbitrary position 369 that is sufficient to encompass any "y" or in-scan dimension jitter due to imperfections in the second transport path 356. The result of these dynamically applied corrections, as indicated by numeral 355' (and the optional use of gripper corrections as already referenced), effectively normalizes the print grid, as indicated by numeral 357". Note that it is also possible to use another transducer 373, or to use drive signal correction techniques 374 and / or position feedback / adjustment techniques as already discussed, to offset the position of part or all of the printhead assembly and correct for cross-scan position errors, as referenced by function box 372.

[0087] Considering the principles discussed thus far, correcting each of the substrate paths to a "virtual" linear edge, and the printhead paths to a "virtual" linear edge, allows both the substrate and the printhead to be positioned in a manner that conforms to the printing grid assumptions (e.g., the printer's coordinate reference system) despite the minute errors imparted by the mechanical system. These techniques may optionally be combined with drive control techniques (or other described techniques for correcting each transport along that transport dimension) to further improve system accuracy. Again, these techniques can also be extended to other motion dimensions and processing and / or mechanical systems.

[0088] FIG. 3E presents another example 375, i.e., an alternative embodiment in which errors in one transport path can be corrected using one or more transducers “T” associated with a second transport path. In this case, the gripper assembly can be assumed to include two linear transducers, again controlled in common and differential modes to achieve cross-scan offset and rotation correction without a fixed pivot point. Note that in this case, the errors are again on the scale of microns or nanometers. The depicted angles and offsets are therefore greatly exaggerated in the figure to aid in explanation. In this case, the figure shows icons for “two grippers”, but in reality these represent the exact same grippers and gripper positions along the “in-scan” dimension for two separate scans. However, in this case, one of the transport paths (i.e., path 356 with respect to the printhead assembly) does not have its own transducer-based error correction system (or optionally, it has such a system, but the depiction corresponds to an implementation in which the gripper error correction system would be further driven to correct for coordinate axis non-orthogonality). The gripper error correction system is therefore controlled in this embodiment to also correct print head transport path jitter orthogonal to the light beam 371, or for non-orthogonality between transport paths. That is, detected deviations (or non-orthogonality) in the print head transport path are corrected in this embodiment by adding additional mitigation offsets into the gripper second component 303, for example by combining deviations / error corrections from a desired path of multiple transport systems. In this embodiment, therefore, the two grippers should be assumed to represent two alternative sets of transducer control signals that respectively correct the print head system errors (or non-orthogonality) {Δi0, Δj0, and Δφ0} at print head position 373′ and the print head system errors (or non-orthogonality) {Δi1, Δj1, and Δφ1} at print head position 373″ (i.e., corresponding to the individual scans).That is, with reference to FIG. 3B , even though the gripper transport in the “y” dimension is assumed to be corrected to an ideal edge (with respect to the gripper transport path) through the use of mitigating offsets and angles provided by the gripper system's transducers, in one embodiment, these same transducers may also be used to correct errors in the print head path (or other errors). As depicted, further offsets and / or rotations are added to effectively reposition the substrate to have an intended position and orientation relative to the print head (e.g., to produce motion in a manner that matches the print head errors, as represented by alternative transformed edges 107′″ and 107′″). Other error correction techniques can also be applied to enhance these processes.

[0089] As the above discussion implies, while the previous examples show correction of errors in one or two transport paths, the principles described with reference to FIG. 3E can be applied to correct fine errors in any number of transport paths, e.g., one, two, three, four, five, etc., where corrections for multiple transport paths are applied to a single drive path (e.g., to a transducer used for substrate transport) or to correct errors in a first number of transport paths via mitigation corrections applied to a second, fewer transport paths. As described, the discussion also applies to correction of non-orthogonality, e.g., where the gripper and printhead transport paths are not exactly 90 degrees separated. This can be treated as equivalent to the case of measured printhead x-position dependent errors, with corresponding corrections applied by offsetting the transported components in either transport system. It should also be noted that while the term "transport path" is illustrated in the figures as a position change along a curved path, the principles and fine error correction procedures discussed above can also be applied to correct for fine errors in any dimension (i.e., including rotation and precise angular orientation); for example, in embodiments in which the mechanism is rotated, it is possible to measure the angular change rate or orientation "jitter" and use transducers and / or drive signal corrections as illustrated above to correct for such fine errors. Finally, while FIG. 3E illustrates incorporating printhead transport path errors (or other non-gripper errors) into the gripper correction, it is contemplated that these various transport paths are interchangeable; for example, gripper system position errors may be corrected using printhead system error correction transducers.

[0090] FIG. 3F shows that the techniques presented above can be embodied in many different forms to correct transport path errors, generally as represented by numeral 381. In the context of a printer for manufacturing applications, a print recipe can be pre-stored or cached in a manner that would be used to reproducibly print on many substrates on a continuous basis as part of an assembly line type process, for example, as indicated by numeral 382. As a non-limiting example, the techniques described herein can then be applied to correct fine motion errors along a path associated with the motion of a substrate, the motion of one or more printheads or printhead assemblies, the motion of a camera assembly or inspection tool, and the like. Note that one advantage of a system designed to drive errors to zero is that the effects of various other environmental variables, such as temperature, can be largely ignored from an error correction perspective, and path deviations drive path corrections such that the position and orientation during transport is precisely matched to the motion of the light beam or guide, whatever the temperature may be. These techniques allow automatic correction of motions along these transport paths for minute errors, such that the motion of the substrate (or, optionally, any of these systems) is made to correspond to an ideal path, even though the actual transport drive mechanisms (e.g., motions of grippers, edge guides, travelers, etc.) are still hindered by path errors that impart unintended offsets, nonlinearities, and other errors. Generally speaking, the corrections are made by a subsystem independent of the print recipe, in a manner that allows for print planning and assumes that the substrate is ideally placed. For example, the structures described herein provide, in one embodiment, a means for countering errors or unintended offsets "Δx" in a first dimension relative to the transport path, the first dimension being independent of the transport path (meaning that it includes at least one component orthogonal to it). Such a means may comprise at least one transducer controlled as a function of the transport path position to reduce or eliminate "Δx", as represented by numeral 383 in FIG. 3F.Such means generally comprise transducers that are electronically controlled to achieve positional displacements in response to dynamic errors that vary according to position along the transport path and / or other factors. As represented by numeral 384, these structures (or different, potentially overlapping sets of structures) can provide means for defining a virtual edge at a specific, arbitrary location in a first dimension (e.g., at "x3" in the embodiment from FIG. 3F) and offsetting the gripper components to such location relative to the transport path (or the structure being transported). As before, such means also generally comprise transducers and associated hardware and / or instruction logic that cause the transducers to nullify or equalize the errors. By numeral 385, in another embodiment, the structures described herein provide means for countering errors "Δy" in a second dimension relative to the transport path. This second dimension is optionally independent of the transport path, but can (alternatively) represent a common dimension to the transport path, or may otherwise be generally synonymous with the transport path. Such means may optionally comprise at least one transducer controlled in response to the transport path position (and / or other factors) to reduce or eliminate "Δy", such as, for example, for the embodiments depicted above, by correcting the position of the "thing" being transported or otherwise adjusting the speed or motion along the transport path, or using a position feedback system as already referenced. In yet another variation, the same structure that may be applied to counter "Δy" by numeral 386 may provide a means to define a virtual edge at a specific (absolute or relative) position in the second dimension (e.g., at a non-zero "y3" for the above embodiment) and offset the transport path (or the structure being transported) to such position. Such means also generally comprise a transducer and logic that causes the transducer to effect a positional displacement in response to a dynamically sensed error as the object is advanced along the transport path.In one embodiment, the means can include another transport path or associated error correction system, such as an error correction system associated with the printhead transport (e.g., to compensate for nozzle firing time, substrate, printhead or other position errors, or other sources of error). In yet another embodiment (387), a transducer similar to that discussed above can be applied to counter rotational errors (Δθ). In one embodiment, the means can include a single transducer that converts electrical energy into structural rotation, while in other embodiments, two or more position transducers can be applied in the same vein. For example, as discussed above, one implementation can use two voice coils, each a linear transducer that, when operated independently, provides rotational adjustment of what is being transported, and a floating mechanical pivot mechanism is used to support the voice coils and provide structural rigidity. These structures (or different, potentially overlapping sets of structures) may also provide means for defining a virtual edge in a specific (absolute or relative) angular relationship to the first and second dimensions discussed above (e.g., "θ3" in the above embodiment) (388) and for offsetting the transport path (or the structure being transported) in a manner corresponding to such orientation. In yet another embodiment (389), the structures described herein provide means for accommodating an offset "Δz" in a third dimension relative to the transport path, the third dimension optionally being independent of the transport path and the first and second dimensions referenced above. Such means may again comprise at least one transducer controlled by hardware and / or software logic in response to the dynamically measured error to reduce or eliminate that error. The transducer and supporting logic may also be used to define a virtual edge in Z3 (390). Numeral 391 and the associated set of ellipses allow these techniques to be applied to multiple degrees of freedom, including corrections and / or offsets in any of the three positional dimensions and any of the three rotational dimensions (i.e., yaw, pitch, and / or roll).In some embodiments, means for correcting misalignment can be applied to align the substrate to the printer's coordinate reference system, as represented by numeral 393. Such means can include position sensors such as cameras, handlers or other transport devices, processors, and associated support instructions and / or hardware logic for repositioning the substrate relative to the desired print (or conversely, adjusting the print to match a misaligned substrate). Means for correcting print head (PH) errors and / or aligning the print head (PH), as referenced above, can include a converter with a floating pivot point and / or support for common and differential correction modes, as referenced above. The system can also include means for realigning or adjusting the light source, as represented by numeral 396, to provide a calibrated path and / or printer coordinate reference system (e.g., by adjusting the laser attitude and yaw). The system can also include means for correcting non-orthogonality of the coordinate reference system (397).

[0091] It should be noted that each reference to a dimension, e.g., "x", "y", "θ", or other dimension, is arbitrary, i.e., they may refer to any dimension and are not limited to Cartesian, rectangular, regular or rectilinear coordinates. In one embodiment, the "x" and "y" dimensions correspond to the "cross-scan" and "in-scan" dimensions, respectively, of the processing system, although this need not be true in all embodiments.

[0092] By correcting for motion errors in such a manner, the described processes provide a "virtual" and / or ideal and / or straight transport path even though the mechanical motion system may still be disturbed and continue to follow existing repeatable imperfections. When applied in the context of manufacturing systems such as the aforementioned industrial printers, these techniques provide a powerful tool to enable precision positioning and manufacturing.

[0093] II. ONLINE AND OFFLINE PROCESSES ASSOCIATED WITH SEGMENT SHAFT MANUFACTURING SYSTEM Figures 4A-5 are used to discuss some of the details associated with a typical split-axis processing system. Figure 4A is used to discuss a typical scanning motion used in the processing system to deposit material that will form a layer of an electronic device, while Figure 4B is used to discuss the configuration of a specific manufacturing system that relies on a printer and a processing chamber. Figure 4C will be used to discuss a process in which each substrate in a series of substrates is aligned with a coordinate reference system used by the printer, while Figure 5 will be used to discuss the processing of an electronic device (or a specific layer of such a device).

[0094] More specifically, FIG. 4A depicts a substrate 401 along with several dashed boxes representing individual panel products. One such product, seen at the bottom left of the figure, is designated using reference numeral 402. Each substrate (in a series of substrates) has, in one embodiment, several registration marks as represented by numeral 403. In one embodiment, two such marks 403 are used on the substrate as a whole, allowing measurement of substrate position offset relative to mechanical components of the printer (e.g., grippers), while in another embodiment, three or more such marks 403 are used to facilitate additional adjustments (e.g., rotational adjustments). In yet another embodiment, each panel (such as any of the four depicted panels) is accompanied by a per-panel registration mark such as mark 405, this latter approach allowing gripper adjustments so that each panel being printed is precisely aligned to the printer's coordinate reference system. Whatever approach is used, one or more cameras 406 are used to image the registration marks to identify the substrate position relative to the printer's coordinate reference system. In one embodiment, a camera is mounted on each of the gripper and the advancing printhead assembly, and these cameras can each be controlled to image one or more substrate fiducials and identify precise substrate (and / or product) position and orientation relative to a position along the printer's transport axis (i.e., relative to the printer's coordinate reference system). In another contemplated embodiment, a single stationary camera is used, and the printer's transport mechanism (e.g., a handler and / or air float mechanism) moves the substrate to sequentially position each registration mark within the field of view of the single camera. In a different embodiment, the camera is mounted on a two-dimensional motion system for transport relative to the substrate. In yet another embodiment, low and high magnification images are taken, the low magnification image coarsely locating the fiducials for the high resolution magnification, and the high magnification image identifying precise fiducial positions according to the printer coordinate system. Line or CCD scanners can also be used.Considering the previous discussion, in one embodiment, the printer's transport mechanism (and associated feedback / position sensing mechanism) controls the motion to within about a micron of the intended position, and an imaging system is used for each substrate to align (and optionally mechanically reposition) the substrate to the printer's coordinate reference system until reasonably accurate alignment is achieved. In another embodiment, the measured position and / or orientation errors can be used to customize / adjust the printing recipe in software, such that the print is skewed to match the detected substrate position / or orientation.

[0095] In a typical implementation, printing will be performed to deposit a given layer of material over an entire substrate at once (i.e., with a single printing process providing layers for multiple products). Such deposition can be performed within individual pixel wells (not shown in FIG. 4A; i.e., there would typically be millions of such wells for a television screen), such as depositing an emissive layer within such wells, or on a "blanket" basis, such as depositing a barrier or protective layer such as an encapsulation layer. Regardless of which deposition process is in question, FIG. 4A shows two illustrative scans 407 and 408 along the long axis of the substrate. In a split-axis printer, the substrate is typically moved back and forth (i.e., in the direction of the depicted arrows) with the printer advancing the printhead positionally (i.e., perpendicular to the page of the drawing) between scans. Note that while the scan path is depicted as linear, this is not required in any embodiment. Also, while the scan paths (e.g., 407 and 408) are illustrated as being adjacent and mutually exclusive in terms of area covered, this is also not required in every embodiment (e.g., the print head can be applied on a portion-by-portion basis to swaths of printing as needed or desired). Finally, note also that any given scan path will typically pass across the entire printable length of the substrate, printing layers for multiple products in a single pass. Each pass uses nozzle firing decisions according to a printing recipe, and control over the transducers (not shown in FIG. 4A ) is used to ensure that each drop in each scan is deposited precisely where it should be deposited relative to the substrate and / or panel boundaries.

[0096] FIG. 4B illustrates one contemplated multi-chamber processing apparatus 411 that can be used to apply the techniques disclosed herein. Generally speaking, the depicted apparatus 411 includes several general modules or subsystems, including a transfer module 413, a printing module 415, and a processing module 417. Each module maintains a controlled environment so that printing can be performed, for example, by the printing module 415 in a first controlled atmosphere and other processing can be performed, for example, another deposition process, such as an inorganic encapsulation layer deposition (for the printed material, for example) or a curing process, in a second controlled atmosphere. These atmospheres can be the same, if desired. The apparatus 411 uses one or more mechanical handlers to move substrates between modules without exposing the substrates to an uncontrolled atmosphere. It is possible to use other substrate handling systems and / or specific devices and control systems within any given module that are adapted to the processing performed for that module. Within the printing module 415, as discussed, mechanical handling can include the use of floating tables, grippers, and alignment / micro-error correction mechanisms (in a controlled atmosphere), as discussed above.

[0097] Various embodiments of the transfer module 413 can include an input load lock 419 (i.e., a chamber that provides buffering between different environments while maintaining a controlled atmosphere), a transfer chamber 421 (also having a handler for transporting the substrate), and an atmospheric buffer chamber 423. Other substrate handling mechanisms, such as a floating table, can be used within the print module 415 for stable support of the substrate during the printing process. In addition, an xyz motion system (such as a split axis or gantry motion system) can be used to reposition and / or realign the substrate to the printer, to provide precise positioning of at least one print head relative to the substrate, and to provide a y-axis transport system for transport of the substrate through the print module 415. It is also possible within the print chamber to use multiple inks for printing, e.g., using separate print head assemblies, so that, e.g., two different types of deposition processes can be performed within the print module in a controlled atmosphere. The printing module 415 can include a gas enclosure 425 that houses the inkjet printing system along with means for introducing a non-reactive atmosphere (e.g., nitrogen or a noble gas) and otherwise controlling the atmosphere for environmental conditioning (e.g., temperature and pressure, gas composition and presence of particulate matter).

[0098] Various embodiments of the processing module 417 can include, for example, a transfer chamber 426, which also includes a handler for transporting the substrate. In addition, the processing module can also include an output load lock 427, a nitrogen stack buffer 428, and a curing chamber 429. In some applications, the curing chamber can be used to cure, bake, or dry the monomer film into a uniform polymer film. For example, two specifically contemplated processes include a heating process and an ultraviolet radiation curing process.

[0099] In one application, the apparatus 411 is adapted for mass production of liquid crystal display screens or OLED display screens, for example, fabricating an array of (for example) eight screens at a time on a single large substrate. The apparatus 411 can support an assembly line type process such that a series of substrates are processed in succession, one substrate being printed on and then advanced for curing while a second substrate in the series is simultaneously introduced into the printing module 415. The screens produced in one embodiment can be used in televisions and as display screens for other forms of electronic devices. In a second application, the apparatus can be used in the mass production of solar panels in much the same manner.

[0100] The printing module 415 can be advantageously used in such applications to deposit organic light-emitting layers or encapsulation layers that help protect sensitive elements of an OLED display device. For example, the depicted apparatus 411 can be loaded with a substrate and controlled to move the substrate between various chambers in a manner uninterrupted by exposure to uncontrolled atmosphere during the encapsulation process. The substrate can be loaded via an input load lock 419. A handler located in the transfer module 413 can move the substrate from the input load lock 419 to the printing module 415, and after completion of the printing process, the substrate can be moved to a processing module 417 for curing. By repeated deposition of subsequent layers, each of controlled thickness, a cohesive encapsulation can be built up to suit any desired application. Again, it is noted that the techniques described above are not limited to encapsulation processes, and many different types of tools can be used. For example, the configuration of the apparatus 411 can be varied to place the various modules 413, 415, and 417 in a different juxtaposition, and additional fewer or different modules can also be used. In one embodiment, the depicted apparatus 411 can be coupled with other modules and / or systems to potentially produce other layers of a desired product (e.g., via different processes). When the first substrate in the series is completed (e.g., processed to deposit materials that will form the layer at issue), another substrate in the series is then introduced and processed in the same manner, e.g., according to the same recipe.

[0101] Figure 4B provides one example of a set of linked chambers or processing components, but clearly other possibilities exist. The techniques introduced above can be used to control processing processes performed with the device depicted in Figure 4B, or indeed by any other type of deposition equipment.

[0102] Once printing is finished, the substrate and wet ink (i.e., deposition liquid) can then be transported for curing or processing of the deposition liquid into a permanent layer. For example, a substrate can have the "ink" applied in the print module 415 and then transported to the curing chamber 429, all without disrupting the controlled atmosphere (i.e., advantageously used to prevent moisture, oxygen, or particulate contamination). In a different embodiment, an ultraviolet scanner or other processing mechanism can be used in situ, for example on a split axis traveler in much the same manner as the print head / camera assembly described above.

[0103] FIG. 4C provides another flow chart for system alignment, with a series of steps generally designated using numeral 431. The method begins with system initialization, per numeral 432. For example, this initialization can be performed at each power-up, or on an ad-hoc (e.g., operator command) or periodic basis. An alignment / detection operation 433 is then performed with respect to the various transport paths, for example, to identify a common point as an origin or common reference point, and to identify the precise location of each nozzle within a coordinate reference system established by this point and the position feedback (and position indicators) associated with each transport path. As shown on the left side of the figure, this operation (or system initialization) can be performed when desired, for example, after a maintenance operation, resulting in a change in the printhead or other system components (which may result in the nozzles in a different location relative to the printer's coordinate reference system). Note that numeral 434 represents a typical printhead assembly configuration, i.e., an assembly carrying nine printheads (this may be one larger assembly or several subassemblies, e.g., three "ink sticks," each carrying three printheads in an interleaved configuration). In one embodiment, there may be between 256 and 1,024 nozzles per printhead.

[0104] To elaborate on the alignment procedure, as described by U.S. Provisional Application No. 62 / 459402, a removable optical reticle can be mounted in a known position (e.g., coaxially) with the "down" camera of the printhead assembly, and both the gripper and printhead are geared along their transport paths until this camera and the "up" camera mounted on the gripper "find" each other (i.e., they both image the reticle, e.g., positioned until each camera image finds an associated set of sight lines in the reticle or directly associated captured image). This point can then be used to define a common reference point or origin of the coordinate reference system, as represented by numeral 435. Each transport axis is then moved so that one of these cameras images a fiducial associated with the other's transport system. For example, by numeral 437, the gripper and printhead transport systems are geared until the gripper's "upward facing" camera finds the fiducial or registration marks on the printhead and uses a search algorithm to precisely locate the center point of each print nozzle. The position of each motion system, i.e., gripper / printhead assembly, along its respective transport path (e.g., observed with precise location aided by registration marks from optical tape) then allows for precise definition of this fiducial or registration mark within the printer's coordinate reference system, and so on. Each nozzle can be precisely defined in terms of the printer's coordinate reference system, allowing precise control over where droplets are ejected. For other potential sources of error, for example unintentional non-orthogonality between the transport axes, the error can be detected using additional fiducials or alignment marks (e.g., a fixed fiducial associated with the printer support table is imaged by one or both cameras per numeral 439 and an associated adjustment is made to the coordinate reference system, optical guide system, or recipe), or alternatively the optical guide / laser can be adjusted as part of a manual or electronic calibration process per numeral 440 until precise alignment and orthogonality is achieved.

[0105] Optionally, such a calibration process can be performed periodically, or whenever system parameters are changed, for example, a new printhead is introduced, potentially introducing nozzles at previously known locations relative to the printer's coordinate reference system.

[0106] During run time, the introduction of each substrate in the series of substrates can potentially introduce unintended misalignments between where printing should occur (relative to the printer) and where printing occurs (relative to the substrate). Each substrate thus undergoes a position and / or orientation detection process, per numeral 441, in which associated errors are incorporated into the electronic printing details or to reposition the given substrate for printing of a layer (so that printing occurs in precise alignment with respect to the substrate fiducials and with respect to other layers deposited on the substrate that are also precisely aligned with respect to these fiducials). As each given substrate in the series is introduced into the printing module (e.g., 415 from FIG. 4B), per numeral 442, it is first roughly aligned using one or more bunkers and / or mechanical handlers. Once the given substrate and its associated fiducials are approximately in the correct position, an imaging system (such as a “downward-looking” camera system carried by the printhead assembly) is then employed, per numeral 443, using a search algorithm and suitable image processing to precisely locate one or more substrate fiducials. For example, this detection can be performed using a spiral search pattern or similar search pattern that searches for a reference expected position until a precise reference position and / or orientation is detected. A series of optional and / or alternative correction processes can then be employed to precisely position and / or reposition the substrate. For example, as variously indicated by process box 445, in one embodiment, the aforementioned transducers can be driven to provide precise substrate positioning (e.g., the vacuum lock of the gripper's "second component" is not adjusted, but the transducers are ganged in common drive mode and / or differential drive mode until the substrate reference has exactly the correct starting position and orientation). The transducer positions corresponding to this substrate position / orientation can then be used as zero levels or positions, and (in production) error corrections are then superimposed thereon or otherwise defined relative to these positions. Alternatively or additionally, a mechanical handler can be used to reposition the substrate as needed.As yet another alternative, the recipe can be adjusted in software as disclosed in US Patent Publication No. 20150298153 to correct alignment errors (e.g., with correction of remaining reproducible errors with respect to transducers associated with the gripper and / or print head transport system, as already referenced). Printing then occurs according to the desired printing recipe, per numeral 445. After printing, the freshly printed substrate is unloaded (e.g., transported to a processing chamber) for curing, while the system receives or prepares to receive a new substrate under robotic or human direction.

[0107] FIG. 5 illustrates several different implementation layers, collectively designated by reference numeral 501. Each one of these layers represents a possible separate implementation of the techniques introduced herein. First, the techniques as introduced in this disclosure can take the form of instructions (e.g., executable instructions or software for controlling a computer or printer) stored on a non-transitory machine-readable medium, as represented by graphic 503. Second, by computer icon 505, these techniques can also be optionally implemented as part of a computer or network within a company that designs or manufactures components for sale or use in other products. Third, as illustrated using storage medium graphic 507, the techniques already introduced can take the form of stored printer control instructions as data that, when acted upon, will cause a printer to process one or more layers of a component, relying on the use of different ink volumes or positions that, per the above discussion, mitigate alignment errors. Note that the printer instructions can be transmitted directly to the printer, for example, via a LAN. In this regard, the storage medium graphic can represent (without being limited to) RAM inside or accessible to a computer or printer, or a portable medium such as a flash drive. Fourth, as represented by the processing device icon 509, the techniques introduced above can be implemented as part of a processing apparatus or machine, or in the form of a printer within such an apparatus or machine. It is noted that the particular depiction of the processing device 509 represents one exemplary printer device, for example, as discussed in connection with FIG. 4B. The techniques introduced above can also be embodied as an assembly of manufactured components. For example, in FIG. 5, several such components are depicted in the form of an array 511 of semi-finished flat panel devices that will be separated and sold for incorporation into final consumer products. The depicted devices may have, for example, one or more emissive or encapsulating or other layers that are processed depending on the methods introduced above.The techniques introduced above can also be embodied in the form of end consumer products as referenced, for example in the form of a display screen for a portable digital device 513 (e.g., an electronic pad or a smartphone, etc.), as a television display screen 515 (e.g., an OLED TV), a solar panel 517, or other type of device.

[0108] Having thus discussed in detail the sources of positional error and associated remedies, the present disclosure will now turn to a discussion of more detailed embodiments of specific processing apparatus.

[0109] III. Specific Implementation Figures 6A-6E are used to discuss a specific printer implementation as applied to the manufacture of an OLED display or a solar panel. Depending on the product design, the printers seen in these figures can be used to deposit layers for many products on a substrate at once (e.g., many smartphone or other portable device displays, perhaps hundreds at a time, as conceptually represented by the individual arrayed products on substrate 411 from Figure 4A) or layers for a single product per substrate, such as the display screen of HDTV 415 or solar panel 417 from Figure 4A. Many other exemplary applications will be apparent to those skilled in the art.

[0110] More specifically, Figure 6A shows the printer 601 as having several components that operate to enable reliable placement of ink drops on specific locations on the substrate. Printing in the illustrated system requires relative motion between each printhead assembly and the substrate. This can be accomplished with a motion system, typically a gantry or split-axis system. Either the printhead assembly can move over a stationary substrate (gantry type) or both the printhead assembly and the substrate can move in the case of a split-axis configuration. In another embodiment, the printhead assembly can be substantially stationary while the substrate is moved along both the x and y axes relative to the printhead.

[0111] The printer comprises a printer support table 603 and a bridge 605. The printer support table 603 is used to transport substrates (such as substrate 609) using a planar floating support surface mounted by a frame 604, while the bridge 605 is used to transport several printheads and various support tools, e.g., optical inspection tools, curing devices, etc. As mentioned above, the bridge allows one or more printhead assemblies 611A and 611B to move back and forth along the bridge 605 along the "slow axis", while a gripper (e.g., a vacuum gripper, not seen in this figure) provides a "fast axis" for transporting the substrate (e.g., in what is referred to elsewhere herein as the "y" dimension (e.g., see dimension legend 602)). To accomplish printing, a printhead assembly (e.g., primary assembly 611A) would be positioned at a suitable position along the bridge, while the vacuum gripper moves the substrate in a generally linear fashion along the "y" dimension to provide a first scan or raster. The printhead assembly 611A or 611B is then typically moved along bridge 605 to a different position and stopped, and the vacuum gripper then moves the substrate 609 back in the opposite direction under the new printhead assembly position to provide the subsequent scan or raster, etc.

[0112] The printer support table 603 can have a porous medium that provides a planar floating support surface. The planar floating support surface includes an input zone, a print zone, and an output zone, designated using numerals 606-608, respectively. A substrate 609 is depicted in the input zone 606, ready to be printed. A combination of gas positive pressure and vacuum can be applied through an array of ports or using a distributed porous medium provided by the support table. Such a zone, having both pressure and vacuum control, can be effectively used to provide a fluid spring between the floating table surface and each substrate 609. A combination of positive pressure and vacuum control can provide a fluid spring with bidirectional stiffness. The gap that exists between the substrate 609 and the surface of the floating table can be referred to as the "fly height", and this height is adjusted by controlling the positive pressure and vacuum port conditions. In this manner, the z-axis height of the substrate can be carefully controlled in various portions of the printer support table, including, but not limited to, in the print zone 607. In some embodiments, mechanical retention techniques such as pins or frames can be used to limit the lateral translation of the substrate while it is supported by the gas cushion. Such retention techniques can include using spring-loaded structures, such as to reduce momentary forces incident on the side of the substrate while it is being retained. This can be beneficial because high force impacts between a laterally translating substrate and the retention means can potentially cause chipping or catastrophic failure of the substrate. In other areas of the printer support table, the fly heights do not need to be controlled as precisely, for example, in the input or output zones 606 and 608, or can be controlled to provide different fly heights or fly height profiles. "Transition zones" between areas such as where the pressure-to-vacuum nozzle ratio gradually increases or decreases can be provided. In an illustrative example, there can be an essentially uniform height between the pressure-vacuum zone, the transition zone, and the pressure-only zone, such that within tolerances the three zones can essentially lie in one plane.The fly height of the substrate over the pressure-only zone elsewhere may be greater than the fly height of the substrate over the pressure-vacuum zone, such as to allow sufficient height so that the substrate does not collide with the printer support table in the pressure-only zone. In an illustrative example, the OLED panel substrate may have a fly height of about 150 microns (μ) to about 300μ above the pressure-only zone, and then about 30μ to about 50μ above the pressure-vacuum zone. In an illustrative example, one or more portions of the printer support table 603 or other processing equipment may include an air bearing assembly provided by NewWay Air Bearing (Aston, Pennsylvania, United States of America). Porous media, such as those having physical dimensions defined to occupy the entirety of the substrate 609, or a defined area of ​​the substrate, such as the display area or an area outside the display area, may be obtained from Nano TEM Co., Ltd. (Niigata, Japan), and the like. Such porous media may include pore sizes defined to provide a desired pressurized gas flow over a defined area while reducing or eliminating mura or other visible defect formation.

[0113] In the embodiment of FIG. 6A, a handler or other transport system (not shown) delivers each substrate 609 to an input area 606 of the printer support table 603. A vacuum gripper engages the substrate 609 and transports it from the input zone 606 into the print zone 607, then moves the substrate back and forth for printing, achieving a separate "near frictionless", low particle generating high speed scan along the fast axis of the printer according to a particular recipe. When printing is finished, the vacuum gripper then transports the substrate to the output zone 608, where a mechanical handler takes over and transports the substrate to the next processing device. During this time, a new substrate can be received in the input zone 606, and the vacuum gripper is then transported back to that zone to engage the new substrate. In one embodiment, deposited droplets of ink are allowed to mix together in the output zone, e.g., via a short sit or fix cycle where the substrate is allowed to remain in the output zone, and printing and fixing and subsequent curing are carried out in a controlled environment (e.g., generally in a nitrogen or noble gas atmosphere or other non-reactive environment).

[0114] The depicted printer 601 may also include one or more maintenance or administration bays 612A and 612B, each of which may store tools 615-620, e.g., printheads, cameras, "ink sticks," for modular engagement with one or both printhead assemblies. Similarly, in one embodiment, these bays are configured for interaction with other components, such as a drop measurement module, a purge basin module, a blotter module, and the like, optionally within the same enclosure volume or a second volume. In one embodiment, the printhead assembly can simultaneously load three "ink sticks," as represented by numeral 622, with each "ink stick" supporting three printheads and supporting fluid and circuit contacts in a manner adapted for modular engagement with the printhead assembly. The ink delivery system (not shown separately in FIG. 6A) includes one or more ink reservoirs, ink supply tubing which carries ink between the reservoirs and one or more of the printhead assemblies, and suitable control circuitry, while the motion system (also not shown separately in FIG. 6A) includes electronic control elements such as a subsystem master processor and control system, actuation elements for the gripper and printhead assemblies, and suitable control code.

[0115] Each printhead assembly 611A / 611B includes a traveler 623A / 623B that rides along the bridge (i.e., on a track or guide) and an engagement mechanism 624A / 624B mounted adjacent a front face 625A / 625B of the bridge for robotically engaging and disengaging ink sticks or other tools, as desired, on a modular basis, with respective support bays 612A / 612B. Each printhead assembly (611A / 611B) is supported by a linear air bearing motion system (essentially low particle generation) or other linear motion system to enable it to move along the bridge 605. Each printhead assembly is accompanied by fluidic and electronic connections to at least one printhead, each printhead having hundreds to thousands of nozzles capable of ejecting ink at a controlled rate, velocity, and size. Providing one illustrative example, the printhead assembly can include about 1 to about 60 printhead devices, each of which can have about 1 to 90 printheads, each of which can have 16 to about 2,048 nozzles, each of which can emit droplets having a volume of about 1 to 20 picoliters (pL), depending on the design. Each of the front faces 625A / 625B provides a separate z-axis movement plate that controls the elevation of the engagement mechanism (and thus the printhead or other tool) above the surface of the substrate. The traveler and engagement mechanism can serve as the "first" and "second" components already referenced with respect to the printhead assembly, for example, these components are coupled by an electromechanical interface (not seen in FIG. 6A) that allows for robotic adjustment of the transported tool in each of the x, y, and z dimensions, in one embodiment. In this regard, the already referenced U.S. Provisional Patent Application No. 62 / 459,402 generally provides details regarding the z-axis calibration of the printhead and various other elements of the printer's coordinate reference system.The electromechanical interface may advantageously include stepper motors, fine adjustment screws, and other mechanisms for adjusting (a) the x, y, and / or z mounting of each tool relative to an associated engagement feature, and (b) the pitch between individual tools (e.g., pitch between ink sticks). In addition, each tool may also include various fine adjustment mechanisms, for example, for pitch adjustment between multiple printheads carried by each ink stick. The electromechanical interface may optionally include kinematic or similar mounts for repeatably and reliably engaging each tool to within 1 micron of its intended position in each dimension, along with robotic adjustment mechanisms configured to provide feedback for precise position adjustment of each tool relative to the engagement features.

[0116] The electromechanical interface also advantageously includes a set of transducers as already referenced, e.g., to offset the engagement features 624A / 624B linearly in the "y" dimension relative to the associated traveler 623A / 623B. As should be apparent from the discussion thus far, the provision of a transducer correction feature that provides a "virtual straight edge" for the printhead and another "virtual straight edge" for the gripper (not seen in FIG. 6A ) promotes a printing grid that is more "regular", e.g., helps to ensure uniform drop placement at the precise regular intervals associated with the printing grid, thereby promoting layer uniformity.

[0117] As should be apparent, the depicted structural elements allow control over substrate x-axis position using common mode displacement of the substrate by a separate voice coil assembly, and control over substrate orientation about the θ dimension (i.e., rotation about the z-axis). Various embodiments of the depicted gripper system can maintain substrate orientation parallel to the y-axis of travel within + / - 4,300 microradians or less, depending on implementation. As previously mentioned, when it is also desired to adjust the substrate position to more closely match deviations in the printhead (printhead assembly) position and orientation, this control over orientation along with common mode x-axis displacement, and the effective implementation of a floating pivot point for the substrate, allows precise repositioning of the substrate, simulating a perfect virtual edge (or guide) for each substrate and traveler motion (e.g., printhead, camera, etc.). As previously mentioned, the vacuum gripper and printhead assembly / traveler each also include an optical system (not seen in the figures) for detecting registration marks, i.e., providing electronic position signals precisely indicating the location of the gripper or printhead assembly along the associated transport path.

[0118] As should be observed, the use of the voice coil in combination with the air (gas) bearing support of the substrate and the vacuum-based engagement between the gripper and the substrate provides an efficient mechanism for a frictionless and effective mechanism for both substrate transport and fine position adjustment. The present structure helps to maintain minimal contact interaction with the substrate during electronic component processing (e.g., during layer deposition and / or curing), which helps to avoid distortions and defects that may otherwise occur as a result of substrate deformation, contact-induced local substrate temperature variations, or other effects such as electrostatic energy accumulation. At the same time, the nearly frictionless support and transducer system, in combination, helps to provide a micron-scale or better throw used to perform fine adjustments of the substrate position. These structures help to perform the precise substrate corrections required to obtain one or more "virtual transport paths" despite mechanical imperfections as already referenced, and despite the fact that the substrates serving as deposition targets may be meters long and meters wide. The voice coil can also be configured to provide a relatively large throw, for example, from sub-microns to 100 microns or more, which may be significant depending on the implementation (e.g., when the system in question is subject to this scale of jitter, given its manufacturing tolerances).

[0119] 6B shows the vacuum gripper 631 in additional detail. The vacuum gripper 631 again comprises a first component 633 (riding on a y-axis carriage, not seen in the figure), a second component 635 that engages the substrate, and two linear transducers 637 and 639. As depicted, it should be noted that the second component is positioned vertically above the first component as both are advanced along the gripper's transport direction (e.g., along the "y dimension" depicted by legend 632), and the second component supports a vacuum chuck 643 that is used to selectively engage the substrate. Unlike the previous example, which assumes the use of a virtual pivot point, this example further includes a floating mechanical pivot assembly or mechanism 641 that provides a mechanical linkage between the first and second components 633 / 635 as the gripper is advanced along the y dimension, and helps provide structural support for embodiments in which the linear transducers are embodied as voice coils. The floating pivot mechanism includes a pivot shaft 651, an assembly top plate 653 (mounted to the gripper second component 635), and an x-axis sliding bottom plate 655 that moves on rails relative to a support frame 644 provided by the gripper first component 633. The assembly top plate is preferably made of a relatively thin material to provide flexure and allow, for example, leveling of the gripper second component relative to the substrate and floating table, and is rigidly fixed to the second gripper second component using a mounting bracket 656. Briefly, as component 633 is advanced along the y dimension, the floating mechanical pivot mechanism 641 constrains component 635 to similarly advance along the y dimension while allowing x-axis sliding interaction between these components 633 / 635 and rotation about the floating pivot axis 649.

[0120] The floating pivot point allows for differential or common mode drive of transducers 637 and 639, as discussed above. These various motions are further represented by a set of motion arrows 645 / 647. Generally speaking, each transducer couples a mounting block 657 (e.g., mounted to a frame 644 of a first component of the gripper) and a mounting plate 661 (mounted to a second component of the gripper), and a linear actuator 659 couples the mounting block and mounting plate and provides precision displacement along the x-axis. The design of transducers 637 / 639 and floating mechanical pivot mechanism 641, as represented by dashed outlines 663 and 665, will be shown and discussed in further detail in connection with Figures 6C and 6D.

[0121] FIG. 6B also illustrates the positioning of the optical guide 667 relative to the various components of the gripper. In this design, the beam of light is above the top surface of the offsettable component (635) of the gripper, but below the plane occupied by the substrate. Such a configuration facilitates ease of access for the purpose of adjusting the optical components for the purpose of proper alignment. In an alternative embodiment, the optical guide (i.e., the beam of light in this example) can be directed into the cavity between the first and second components 633 / 655 of the gripper, and thus the beam is seen in a half-dash line traversing the gripper to represent that in such alternative embodiment the beam may be hidden from view at this particular location, for example, as represented by numeral 667′. A beam splitter 668 per transducer is also mounted on the second component 635 of the gripper and is used to redirect the laser light from the optical guide to a detector per transducer, represented by numeral 669. The design of the beam splitter and / or detector 668 / 669 per transducer advantageously features adjustment screws to adjust each so that the beam splitter and / or detector can be aligned, for example, so that the detector reads zero error when the second component of the gripper is ideally positioned relative to the pre-aligned optical guide (667). These various elements are also mounted in one embodiment below the plane occupied by the substrate, but on the top surface of the offsettable component 635 of the gripper. In alternative embodiments, these elements can be mounted elsewhere (e.g., between components 633 and 635, i.e., below the top surface of component 635, in a manner hidden from view). The beam splitter, detector, and adjustment screws are each advantageously positioned to be accessible (e.g., using a screwdriver or other tool) to allow for off-line adjustment for the purposes of this calibration. In alternative embodiments, proper beam splitter and / or detector alignment can be detected, or misalignment can be detected and otherwise incorporated into the correction process.For example, in one embodiment, a test substrate can be introduced, fiducials on the test substrate can be imaged at multiple locations, the misaligned light beam, beam splitter, and / or detector can have readings at different transport path advancement positions that are stored and incorporated into the error correction process at run time, and the transducer correction signal is effectively "skewed" at run time to ideally advance the second component of the gripper based, for example, on preprogrammed adjustments to the readings of the misaligned optical guide or associated optical components. It should also be pointed out that in various other embodiments, the optical components can be configured differently, for example, the detector can be mounted separately from the gripper, and / or the light source can be mounted on the component being transported, and / or various components can be mounted elsewhere.

[0122] Of note, FIG. 6B also shows an “up-looking” camera 670 that is used to image fiducials via a focal path 669 (represented in FIG. 1 as an optical cone) for purposes of aligning the vacuum gripper and printhead assembly (not shown) to define the printer's coordinate reference system and to identify the relative distances and positions of various printhead assembly components (e.g., precise printhead nozzle positions and printhead assembly camera, not shown, in terms of the printer's coordinate reference system), as described above.

[0123] Figure 6C shows a close-up view of the linear transducer 637 from Figure 6B. Again, the other transducer (designated by numeral 639 in Figure 6B) is substantially identical or symmetrical in design to transducer 637.

[0124] More specifically, the linear transducer assumes a voice coil design, in this embodiment, with the gripper first and second components 633 / 635 supported on air bearings. The voice coil is contained within a cylindrical housing 659 to allow displacement of the first component (e.g., vacuum chuck bar and substrate) relative to the second component along the general direction of double arrow 645. An adjustment plate 670 advantageously allows fine adjustment of the transducer xyz orientation as between these two components to linearly move the second component along the x-dimension axis (see dimension legend 632 in FIG. 6B). Again, this can be provided with a manually adjustable screw arrangement that is adjusted and / or calibrated at low frequency. The voice coil in this embodiment has a magnet-based design that provides a fast, precise microscopic throw and displaces the mounting plate 661 in response to an electronic control signal, i.e., again, in the direction of double arrow 645, toward and away from the mounting block 657.

[0125] FIG. 6D shows the floating mechanical pivot mechanism 641 from FIG. 6B. As previously described, the assembly top plate 653 carries a bushing that allows pivoting of the assembly top plate (and gripper second component and vacuum chuck) about the pivot axis 649. This axis is defined by a pivot shaft 651 that extends vertically downward parallel to the z dimension and couples to an x-axis sliding lower plate 655. Although not seen in the figure, the x-axis sliding lower plate 655 is generally coupled to the gripper first component by rails (via the support frame 644) to allow relatively frictionless x-axis displacement of the assembly top plate 653, pivot shaft 651, vacuum chuck 643, and gripper second component 635 relative to the component 633 (and support frame 644), while simultaneously constraining these two components 633 / 635 to move together in the y dimension. This structure provides mechanical support for the floating pivot point, and common and differential mode voice coil displacements are used to provide error mitigation offsets of the second component along the directions of arrow 673 and rotational arrow 675, respectively. Note that the floating pivot point is not required for all embodiments, for example, in embodiments where the transducers provide sufficient output impedance, the mechanical pivot mechanism could potentially be omitted. Regardless of whether a mechanical support structure is used, the floating pivot point advantageously enables common and differential mode control for multiple transducers to reposition the substrate in the x and θ dimensions, thus approximating the ideal transport path of a "straight edge". Various modifications and equivalents will no doubt occur to those skilled in the art.

[0126] FIG. 6E provides a schematic diagram 681 illustrating elements of the pivot mechanism represented by FIGS. 6B-6D. More specifically, this figure now illustrates linear x-axis rails 683 that effectively provide bearings 685 on either side of the x-axis sliding lower plate 655, allowing the structure (and all that is supported above it) to ride in and out of the drawing page. At the same time, the assembly top plate 653 mounts a bushing 686 to allow free rotation of that plate relative to the x-axis sliding lower plate 655 about the pivot axis 649. More specifically, the bushing 686 supports the bearings 689 and enables this rotation. FIG. 6E also illustrates the flexure provided by the assembly top plate 653 relative to the gripper second component 635 and transducers 637 / 639.

[0127] Although the transducer correction mechanism depicted in FIGS. 6A-6D is illustrated in the context of a gripper assembly, the same basic structure can also be used for the printhead assembly (or for each printhead assembly or other tool carrier). Specifically, a first component rides on a track (or x-axis carriage assembly) on gas bearings, while a second component carrying the printhead (or other tool) is displaced in the "y" and / or "z" dimensions depending on the position error in that dimension depending on the x-axis position (and / or other factors, e.g., temperature). For correction in a given dimension, two transducers are again used with a virtual or floating pivot point to achieve both y and θ corrections (or z and xz plane angle corrections) in the relative position of the printhead to the substrate, and in doing so, make the printhead follow a virtual straight edge path. Optionally, two such correction mechanisms can be used together to effectively provide a very precise regular printing grid that provides additional precision over drop placement to provide a straight edge path for each gripper and printhead transport system, respectively. The Z-axis adjustment of the printhead can also be controlled using a transducer-based motion correction system of similar design to provide altitude correction of the printhead orifice plate relative to the substrate surface, thereby managing altitude differences and also with improved accuracy. Other degrees of freedom may also be similarly corrected. In precision motion systems, particularly printer-based processing systems where the coordinate reference system used for printing / manufacturing is effectively related to multiple transport paths, the use of multiple correction systems of this type improves accuracy over droplet landing locations, thus promoting greater uniformity in the processed layers. In turn, this makes it easier to produce thinner layers, e.g., having thicknesses of 5 microns or less. Again, it should be noted that while the designs discussed above emphasize the use of "virtual straight edges" for the purpose of improving the regularity of the printing grid, not all embodiments are so limited, and nearly any desired "ideal" path can be approximated using the teachings provided herein.

[0128] IV. Various Use Cases, Revisited 7A-7I are used to review some specific use cases for the techniques introduced above.

[0129] More specifically, FIG. 7A shows an embodiment 701 in which an optical guide 702 is used to ensure linear motion of a gripper 703 and a substrate 704. The depicted structure implements a continuous process carried out in real time. A robotic gripper (not shown) holds the substrate as it is advanced in the transport system. In the depicted embodiment, the light beam 702 (i.e. the beam generated by the laser source 705) ideally remains parallel to the substrate and at a constant distance from it as the latter is advanced through the system (this is represented by an imaginary linear edge 711). To the extent that deviations occur, the offset (in linear position) and rotation of the second component of the gripper relative to the beam 702 is measured by two laser sensors 706A / 706B. Path deviation measurements from the two laser sensors enable two actuators 707A / 707B (e.g., piezoelectric transducers, voice coils, etc.) to adjust the rotational angle 709 (with respect to an optional mechanical pivot assembly 708) and linear position 710 along a direction perpendicular to the beam to maintain an “ideal” relationship between the second (offsetable) component of the gripper and the beam.

[0130] 7B shows another embodiment 713, but this time the laser source and / or optics 714 are mounted in a fixed relationship to the "thing" being transported and the sensor 715 is stationary. Differential readings over time from the sensor can be used to detect and correct, for example, rotational errors, and steady state beam misalignment can be used to detect and correct the linear position of the thing being transported in a direction orthogonal to the beam 716. As shown by the extended dashed line 717, one variation of this configuration features a stationary laser source such that the beam is directed to the item being transported along line 717 and redirected to the sensor by optics 714 mounted on an offsettable component in a manner that allows detection of deviations from a desired path. Many variations will occur to those skilled in the art, and any mechanism is contemplated, for example, where a light source or other radiation source, beam, detector, etc. is used to detect position deviations. In other embodiments, but not limited to, both the laser source and detector may be stationary while the optics (flat or curved mirrors or beam splitters) are mounted in a fixed manner relative to the offsettable components in a manner that facilitates detection of positional deviations. Whatever design is used, the signal from the sensor is again used to direct the actuators 718A / 718B to maintain beam alignment.

[0131] FIG. 7C illustrates an embodiment 719 in which a sensor 720 is used to calibrate a light source 721, for example, to detect and / or correct a path error 722 relative to an intended path 723. A laser sensor in the vicinity of the laser source is used to optically measure the laser beam direction. If the laser beam direction deviates from the intended path 723, the position of the laser and / or the deflection of its beam is adjusted (manually and / or electronically, under the influence of an electronic control signal) until the intended path is achieved. For example, in one embodiment, the laser mount can be controlled by a piezoelectric (or other) transducer or other deflection means 724 (under the influence of a processing circuit 725) to adjust the tilt and / or rotation of the laser source until proper alignment is obtained. It is noted that advantageously, the laser sensor can be designed to detect path deviations in two dimensions and ideally effect correction of alignment errors using an automatic control loop with a response within milliseconds. It should also be noted that the design of a suitable laser sensor is within the level of one of ordinary skill in the art; for example, in some embodiments, a beam splitter and a four-cell sensor may be used to align the beam, as previously referenced. Many suitable adjustment and sensing mechanisms will occur to those skilled in the art of optics, including, but not limited to, those based on analog designs (e.g., an analog output is generated using a voltage proportional to the position or deflection), convex or concave mirrors and beam splitters, interferometry, and other mechanisms.

[0132] FIG. 7D shows another embodiment 727 in which the light source 728 is improperly aligned. However, unlike the embodiment of FIG. 7C, the deviation between the incorrect optical path 729 and the correct optical path 730 is passively and electronically mitigated, for example, by using a first sensor 731 that detects the error and an actuator 732A / 732B that implements a compensating offset. The signals that control these offsets can be stored in a digital memory 733 and read out during system operation, or can be otherwise added to the dynamic corrections (identified at run-time from the second sensor 734A / 734B) depending on the transport path position, so that the transported object follows the correct path 730. FIG. 7D shows an additional laser position sensor 731 on the left side near the end of the laser beam. This sensor allows the elimination of the sensor 720 (and the associated active laser attitude control represented in FIG. 7C). That is, instead of actively correcting the laser alignment error, the error is measured by an additional laser sensor 731 and corrected using two transducers (ie, depending on the substrate position, while moving the substrate).

[0133] FIG. 7E illustrates an embodiment 735 that implements a zero target control loop. Sensors 736A / 736B dynamically detect deviations from a desired path in one or more dimensions (in this case represented by deviations between a "line of sight" 737A / 737B and a beam 738 from a laser source 739). Processing electronics 740A / 740B preprocess the output from the sensors so that a zero signal is the norm (indicating "no adjustment"). This output is provided to a motion controller (i.e., a processor-implemented zero target controller) 741, which generates a correction signal and provides feedback to a drive transducer 742A / 742B when correction is required, i.e., always, to drive the error to zero. FIG. 7E does not explicitly show the method used to correct the laser alignment error, but without limitation, either the active control method introduced for FIG. 7C or the transducer compensation method represented by FIG. 7D can be used for this purpose, and other methods will occur to those skilled in the art.

[0134] 7F shows an embodiment 745 in which actuators 746A / 746B are driven to keep the transported object (e.g., gripper 747 and substrate 748) always level in terms of z-axis elevation with respect to a beam or optical guide 749. In this case, sensors 750A / 750B detect deviations of the gripper (or other transport mechanism) from the optical guide 749 and drive the two actuators 746A / 746B to even out jitter in elevation or otherwise precisely control the elevation (e.g., to maintain a pre-determined elevation profile to match a zone, etc., as already referenced). A processor-based motion controller 751 can again be used to assist with this purpose.

[0135] FIG. 7G shows an embodiment 755 using two parallel transport systems 756A / 756B for a given transport direction. In this case, whether due to the size of the substrate being received or due to other details of the manufacturing process, it is assumed that the substrate or other transported element 758 is to be transported by multiple traveling components along a parallel transport path, and it is desired that each transport system (i.e., each of the two parallel vacuum gripper systems in this example) is precisely synchronized and controlled to avoid mechanical jitter and / or substrate tilt. To this end, each parallel transport system 756A / 756B has its own optical guide or beam 757A / 757B and transducer compensation system 759A / 759B, each generally corresponding to one of the embodiments described herein. The sensor pairs 761A / 761B and 762A / 762B report signals to a motion controller circuit 763, which controls two motors (not shown), one corresponding to each transport system 756A / 756B. One of the transport systems 756B also carries another light source 765 (e.g., a laser source) which further generates a third optical guide 766, while the other transport system 756A carries a third sensor 767, e.g., a four-cell design as described above. As shown in phantom lines, the path deviation signals from each of the five sensors 761A / 761B / 762A / 762B and 767 are fed to a motion controller circuit which advances or retracts one or both of the motors so that each of the parallel transport systems 756A / 756B is advanced precisely in parallel. For embodiments using multiple transducer correction systems (e.g., to control both x-offset and z-altitude for each lateral displacement and / or flight altitude control), the signals from the third optical guide 766 and third sensor can be used to detect the altitude difference between the second offsettable components (i.e., for each gripper system in this embodiment).Similar to Figures 7C-D, the components associated with the third optical guide may optionally further include components that are used during a calibration mode or process to ensure that the third optical guide is horizontal and perpendicular to the direction of transport provided by the parallel transport system 756A / 756B.

[0136] 7H shows an embodiment 771 in which two conveying systems 772 and 773 used for the orthogonal transport paths each have their own individual laser source 774 / 775 and associated optical guides 777 / 778 and motion controllers 780 / 781. The result is that each motion controller 780 / 781 receives an individual drive or command signal 782 / 783, i.e., as absolute position commands, and errors are corrected transparently to the general system motion control so that it can establish the appropriate position relative to the system coordinate reference system.

[0137] FIG. 7I shows an embodiment 787 in which two transport systems 788 / 789 each have their own source 790 / 791 and sensor pairs 792A / 792B and 793A / 793B, but only one transport system has actuators 794A / 794B that correct the motion jitter. In this case, the motion controller 795 generates transducer control signals 796A / 796B, as introduced above in connection with the discussion of FIG. 3E, such that the actuators 794A / 794B are driven to compensate for the errors associated with the other transport system 788. Non-motion errors, such as errors in the alignment of the optical guides related to either the transport systems and / or non-orthogonality between the transport systems, can also be corrected, as already introduced (this non-orthogonality is represented by two depicted erroneous beam paths 797A / 797B). As represented by the individual correction signals 798A / 798B transmitted to each laser source 790 / 791, one or both light sources can be calibrated electronically (or by mixing any of the optional alignment / calibration techniques already introduced) to correct for non-orthogonality, for example, by realigning the laser paths, adjusting the correction signals provided to the actuators 794A / 794B, etc.

[0138] While various options and use cases are described above, it should be noted that the various techniques and options are considered optional and could be mixed and matched with one another in any permutation or combination. As a non-limiting example, it is possible (and explicitly contemplated) that the embodiment of FIG. 7H could use a zero target controller (and associated "line of sight" sensor, introduced above in connection with the embodiment shown in FIG. 7E). Other combinations, permutations, and modifications similar to one or more of the examples discussed above will no doubt be apparent to those skilled in the art.

[0139] V. Multi-dimensional control of offsettable conveying system components An embodiment of a gripper error correction system as described above can correct errors in multiple dimensions, orthogonal to the transport path and / or orthogonal to the optical guide. As illustrated above, in an environment where the transport system moves a component being transported along a first translation axis (e.g., along the "y" axis of motion), a set of one or more actuators or transducers, such as a voice coil or piezoelectric transducer, can be used to offset the component being transported along a second translation axis (e.g., along the "x" axis of motion), while a set of one or more actuators or transducers, such as a voice coil or piezoelectric transducer, can be used to offset the component being transported (or another component) along a third translation axis (e.g., along the "z" axis of motion), all three of which are mutually orthogonal. In another embodiment, three or more actuators can be used per offsettable component to promote equalization of that component. These various design options will be discussed below in connection with FIGS. 8A and 8B.

[0140] 8A is a cross-sectional view of an assembly 801 that uses two different sets of transducers "T" to correct errors in more than one dimension. More specifically, a first track-guided component 803 of the transport system travels along a first dimension of travel (i.e., in this example, along the "y" axis into the page of the drawing), while a second offsettable component 805 is constrained to travel with the first component along the first dimension of travel. The depicted assembly has two transducer sets, including a set 807 that can be considered to have transducers that displace the second component relative to the first component along the "x" axis, to the same extent as described in connection with the gripper embodiment discussed above, and a second set 809 that can be considered to have transducers that displace the second component relative to the first component along the "z" axis to adjust the flight altitude. In this example, the second transducer set is considered to have three transducers and associated contact points c1-c3 to optionally enable automatic planar equalization of the second component 805 along the "z" axis (i.e., to accommodate unintentional tilt of the second component in the xz and yz planes). As represented by numeral 805' and broken linkage 806, the second component can be optionally structured as two or more components, for example, offsettable from each other along the "z" axis and offset as a group from the first component along the "x" axis. Each transducer set is considered to include a mechanical linkage / support structure (labeled "M" in the figure), such as the floating pivot plate assembly or structural support analogues discussed above, to structurally constrain components 803 and 805 to move together along the "y" axis while allowing offsettable component 805 to advance in the x and z dimensions relative to first component 803.

[0141] FIG. 8B is a cross-sectional view of another assembly 831 that uses two different sets of transducers "T" to correct for errors in more than one dimension. In this view, a first component is represented by numeral 833 while a second offsettable component is represented by numeral 835. These components are also constrained to travel together along the "y" axis while in this example being selectively offsettable from one another in the direction of arrow 836 (i.e., along the "x" axis). In one embodiment, these components are structurally the same as the gripper design of FIG. 6B, where a set of transducers is used to achieve displacement in the direction of arrow 836, and the mechanical linkage between components 833 and 835 is not visible in the figure.

[0142] To correct for the fly-height in this example, the second component 835 again supports a vacuum chuck 839, represented by dashed line 845, that is used to engage the substrate. One or more transducers 837 are used to selectively displace the vacuum chuck 839 along the "z" axis in the direction of arrow 841. In this case, the vacuum chuck 839 is also supported by flexures 843, which provide a spring force that allows for a slightly negative "z" axis displacement of the vacuum chuck 839 and substrate 845 when no force is exerted by the one or more transducers 839, but also provide sufficient spring force to allow for a slightly positive "z" axis displacement of the vacuum chuck 839 and substrate 845 when the transducers are actuated to their full throw. Depending on the embodiment, the transducers can be piezoelectric transducers when the required throw is less than about 3 microns, while a voice coil or similar transducer can be used for larger throws, for example 5 microns or more. Other types of actuator scans can also be used depending on the embodiment.

[0143] In this example, flexures are used to provide structural support that constrains the two components to travel together along the "y" axis (e.g., as seen in FIG. 6D) along with a floating pivot assembly, although other types of structures that perform these functions will no doubt occur to those skilled in the art. The examples presented above are, as a result, to be considered merely illustrative, and not limiting.

[0144] VI. Conclusion Considering the various techniques and considerations introduced above, manufacturing processes can be implemented to mass-produce products quickly at low per-unit costs. When applied to display device or solar panel manufacturing, e.g., flat panel displays, these techniques allow for high-speed panel-by-panel printing processes, where multiple panels are optionally produced from a common substrate. By providing high-speed, repeatable, error-free printing techniques (e.g., using common inks and printheads for each panel), it is believed that printing can be substantially improved, e.g., reducing printing time per layer to a small fraction of the time that would be required without the techniques described above, while ensuring consistent precision deposition of inks all within the desired target area of ​​each substrate. Returning again to the example of a large HD television display, it is believed that each color component layer can be accurately and reliably printed for large substrates (e.g., 8.5 generation substrates that are approximately 220 cm x 250 cm) in 180 seconds or less, or even 90 seconds or less, which represents a substantial process improvement. Improving the efficiency and quality of printing paves the way for a significant reduction in the cost of producing large HD television displays, and therefore lower end-user costs. As mentioned above, display manufacturing (and specifically OLED manufacturing) is one application of the techniques introduced herein, but these techniques can be applied to a wide variety of processes, computers, printers, software, manufacturing equipment, and end devices, and are not limited to display panels. In particular, it is anticipated that the disclosed techniques can be applied to any process in which a printer is used to deposit multiple product layers as part of a common printing operation, including, but not limited to, many microelectronic applications.

[0145] It is noted that the described technique offers a number of options. In one embodiment, panel (or product-by-product) misalignment or skew can be adjusted on a product-by-product basis within a single array or on a single substrate. The printer scan path can be planned such that orientation misalignment of the substrate (or other transported item such as a print head) is automatically compensated for via transducers coupling the substrate and the transport system (e.g., grippers) without requiring adjustment / adaptation based on one or more alignment errors. In one embodiment, transducer corrections can be used to mitigate errors within different transport paths (e.g., print head transport paths), or multiple transducers or transducer sets can be used to correct multi-dimensional position and / or orientation errors. In various embodiments, as described, errors are not pre-measured, but rather dynamically detected and used to fine-tune the substrate and / or individual panel positions to provide perfect alignment.

[0146] Also, while various embodiments illustrate the use of a gripper (or mechanism coupling the substrate to a transport mechanism) and the use of two transducers to achieve fine adjustment, other embodiments may use a different number of these elements. For example, in one embodiment, two or more grippers, each with their own dedicated transducer, may be used. In addition, while the techniques described above are illustrated as applied to a printer using a vacuum gripper system, many other applications may benefit from the techniques described, including applications using a different type of transport mechanism, a different type of printer, a different type of deposition mechanism, or another type of transport path or mechanism. Clearly, many variations exist without departing from the inventive principles described herein.

[0147] In the foregoing description and accompanying drawings, specific terms and drawing symbols have been set forth to provide a thorough understanding of the disclosed embodiments. In some cases, the terms and symbols may imply specific details that are not required to practice these embodiments. The terms "exemplary" and "embodiment" are used to express examples rather than preferences or requirements.

[0148] As shown, various modifications and changes may be made to the embodiments presented herein without departing from the broader spirit and scope of the present disclosure. For example, a feature or aspect of any of the embodiments may be applied in combination with any other of the embodiments, or in place of its corresponding feature or aspect, at least where practical. Thus, for example, not all features are shown in each and every drawing, and it is assumed that, for example, a feature or technique shown according to an embodiment of one drawing can be adopted as an element of or in combination with a feature of any other drawing or embodiment, even if not specifically declared in this specification. Thus, the present specification and drawings are to be regarded in an illustrative sense, not a restrictive sense. The present invention provides, for example, the following: (Item 1) 1. An apparatus for processing a layer of an electronic product, comprising: a printhead for depositing material onto a substrate, said material forming said layer; a transport system that transports at least one of the substrate and the print head during deposition of the material; and a component of the conveying system advanced along a transport path; an optical system comprising a light beam directed parallel to the transport path and a detector for detecting the light beam, the optical system configured such that deviations of the component in at least one dimension independent of a direction of the light beam are detected by the detector; at least one transducer actuated to displace the component in a direction perpendicular to the transport path in response to the deviation; An apparatus comprising: (Item 2) 2. The apparatus of claim 1, wherein the advancement of the component is characterized by mechanical imperfections that generate at least one of a translation error and a rotation error that affects the deposition of the material on the substrate, and the at least one is actuated to equalize the at least one error. (Item 3) The component transports the print head, and the at least one transducer adjusts the print head in response to the deviation so that the print head travels parallel to the light beam. 2. The device according to item 1, which is driven. (Item 4) 2. The apparatus of claim 1, wherein the component is part of a gripper system that transports the substrate along the transport path, and the at least one transducer is driven in response to the deviation so that the substrate travels parallel to the light beam. (Item 5) the transport system is a first transport system, the transport path is a first transport path, the optical system is a first optical system, the component is a first component, and the at least one transducer is part of a first transducer set; The apparatus also includes: a second transport system for transporting a second component along a second transport path, the second component carrying the print head; and a second optical system comprising a second light beam directed parallel to the second transport path and a second detector detecting the second light beam, the second optical system configured such that deviations of the print head in at least one dimension independent of a direction of the second light beam are detected by the second detector; a second transducer set comprising at least one transducer operatively coupling the second transport path and the print head, the second transducer set being driven in response to the deviation of the print head in the at least one dimension independent of the direction of the second light beam; 5. The apparatus according to item 4, comprising: (Item 6) the detector is configured to detect deviations of the component in at least two degrees of freedom independent of the direction of the light beam; 2. The apparatus of claim 1, wherein the at least one transducer comprises at least two transducer sets, each transducer set being driven in response to a deviation of the component in a corresponding one of the at least two degrees of freedom so as to equalize the deviation in the corresponding one of the at least two degrees of freedom. (Item 7) 3. The apparatus of claim 2, wherein the detector comprises a four-cell sensor and the at least two degrees of freedom comprise movement in two independent dimensions, each orthogonal to the direction of the light beam. (Item 8) 2. The apparatus of claim 1, wherein the detector comprises at least two sensors, each of the at least two sensors configured to detect a deviation of the component in a common dimension independent of the direction of the light beam, and the at least two sensors configured to detect a rotation of the component relative to the direction of the light beam responsive to a difference between deviations detected by each of the at least two sensors along the common dimension. (Item 9) 2. The apparatus of claim 1, wherein the component comprises a vacuum gripper that selectively engages the substrate using a vacuum, the vacuum gripper transporting the substrate along the transport path. (Item 10) 2. The apparatus of claim 1, wherein the optical system comprises a laser source, the light beam comprises a laser beam, and the component mounts at least one of the laser source, the detector, and beam redirecting optics in a manner such that movement of the component in a direction perpendicular to the direction of the light beam is detected by the detector. (Item 11) the transport system is a first transport system, which transports the substrate; the transportation path is a first transportation path, and the optical system is a first optical system; The apparatus also includes: a second component associated with the second transport system that transports the print head along a second transport path during deposition of the material; and a second optical system comprising a second light beam directed parallel to the second transport path and a second detector that detects the second light beam, the second optical system configured such that a deviation of the second component in at least one dimension independent of a direction of the second light beam is detected by the second detector; means for identifying non-orthogonality between the first transportation path and the second transportation path; Item 2. The device according to item 1, comprising: (Item 12) 2. The apparatus of claim 1, wherein the at least one converter comprises at least three converters operatively coupling the transport path and the component, the at least three converters being driven in response to the deviation so as to equalize it as the component is advanced along the transport path. (Item 13) 2. The apparatus of claim 1, wherein the at least one transducer comprises at least two transducers each selectively displaces the component in a common direction perpendicular to the direction of the light beam, the at least two transducers being driven in a common mode to displace the component in the common direction, and the at least two transducers being driven in a differential mode to rotate the component relative to the common direction. (Item 14) Item 14. The apparatus of item 13, wherein each transducer of the at least one transducer comprises at least one of a voice coil, a linear actuator, and a piezoelectric transducer. (Item 15) The component is a second component, the transport system comprises a gripper, the gripper comprising a first component constrained to travel along the transport path and the second component; Item 14. The apparatus of item 13, wherein the gripper also comprises a mechanical structure operably coupling the first component with the second component, the mechanical structure constraining the second component to progress with the first component along the transport path while allowing the at least one transducer to displace the second component from the first component in the at least one dimension to even out the deviation. (Item 16) Item 16. The apparatus of item 15, wherein the at least one transducer comprises at least two transducers each selectively displaces the component in a common direction perpendicular to the direction of the light beam, the mechanical structure configured to provide a mechanical pivot point that is similarly displaced in the common direction upon actuation of the at least two transducers, the at least two transducers being driven in a common mode to displace the component in the common direction and in a differential mode to rotate the component relative to the common direction. (Item 17) 2. The apparatus of claim 1, further comprising means for adjusting the direction of the light beam relative to the transport path. (Item 18) Item 10. The apparatus of item 1, further comprising means for detecting angular misalignment between the light beam and the transport path. (Item 19) 1. A method for depositing material and processing a layer of an electronic product, the method comprising: depositing droplets of the material onto a substrate using a print head; The material forms the layer; and transporting at least one of the substrate and the print head during deposition of the material using a transport system; advancing a component of the transportation system along a transportation path; directing a light beam parallel to the transport path and detecting the light beam using a detector in a manner to detect deviations of the component in at least one dimension independent of a direction of the light beam; driving at least one transducer to displace the component in a direction perpendicular to the transport path in response to the deviation; A method comprising: (Item 20) 1. An apparatus for depositing material and processing a layer of an electronic product, the apparatus comprising: means for depositing droplets of said material onto a substrate using a print head, said material forming said layer; and a transporting means for transporting at least one of the substrate and the print head during deposition of the material, the transporting means comprising a component that is advanced along a transport path; and a light beam directed parallel to the transport path; means for detecting a deviation of the component in at least one dimension independent of a direction of the light beam using a detector configured to detect the light beam; means for driving at least one transducer to displace the component in a direction perpendicular to the transport path in response to the deviation; An apparatus comprising: Uses, alternatives, modifications, and improvements are also possible.

Claims

1. 1. An inkjet printer, comprising: A support table; a first component moving in a y-direction along a path; a second component coupled to the first component by a linear transducer, the second component moving in an x-direction orthogonal to the y-direction; A light source; an optical detector coupled to the second component that detects light directed by the light source; a controller operably coupled to the optical detector and the linear transducer and configured to control movement of the second component in the x-direction in response to a signal output by the optical detector.

2. The inkjet printer of claim 1 , wherein the first component and the second component are components of a transport system for transporting a substrate.

3. The inkjet printer of claim 1 , wherein the light source is a laser source.

4. The inkjet printer of claim 1 , wherein the second component is a vacuum gripper.

5. 10. The inkjet printer of claim 1, wherein the second component is coupled to the first component by a mechanical pivot mechanism.

6. The inkjet printer of claim 3 further comprising an adjustment mechanism coupled to the laser source.

7. 10. The inkjet printer of claim 1, wherein the second component is a vacuum gripper, and the second component is coupled to the first component by a mechanical pivot mechanism.

8. 6. The inkjet printer of claim 5, wherein the linear converter is a first linear converter and further comprising a second linear converter, the mechanical pivot mechanism being located between the first linear converter and the second linear converter.

9. 9. The inkjet printer of claim 8, wherein the controller is also operably coupled to the second linear converter and is further configured to actuate the second linear converter to move the second component in the x-direction relative to the first component based on a signal output by the optical detector.

10. 10. The inkjet printer of claim 9, wherein the controller is further configured to actuate the first linear transducer and the second linear transducer to rotate the second component relative to the mechanical pivot mechanism.

11. The inkjet printer of claim 1 , wherein the first component travels along the path on an air bearing.

12. The inkjet printer of claim 1 , wherein the second component comprises a flexure.

13. 1. An inkjet printer, comprising: A support table; a first component moving in a y-direction along a path; a first linear transducer, a second linear transducer, and a second component coupled to the first component by a floating mechanical pivot mechanism, the second component moving in an x-direction orthogonal to the y-direction; A light source; an optical detector coupled to the second component that detects light directed by the light source; a controller operably coupled to the optical detector and the linear transducer and configured to control movement of the second component in the x-direction in response to a signal output by the optical detector.

14. 14. The inkjet printer of claim 13, wherein the first component and the second component are components of a gripper.

15. The inkjet printer of claim 14 , wherein the gripper comprises a vacuum chuck.

16. 14. The inkjet printer of claim 13, wherein the light source is a laser source, the laser source further comprising means for adjusting an orientation of the laser source relative to the path.

17. The inkjet printer of claim 13 , wherein the controller is further configured to rotate the second component relative to the mechanical pivot mechanism.

18. 1. An inkjet printer, comprising: A support table; a first component moving in a y-direction along a path; a first linear transducer, a second linear transducer, and a second component coupled to the first component by a floating mechanical pivot mechanism, the second component moving in an x-direction orthogonal to the y-direction; a bridge that is suspended on the support table and extends in the x-direction; A light source; an optical detector coupled to the second component that detects light directed by the light source; a controller operably coupled to the optical detector and the linear transducer and configured to control movement of the second component in the x-direction in response to a signal output by the optical detector.

19. 20. The inkjet printer of claim 18, wherein the controller is further configured to operate the linear transducer to correct for position errors of the second component.

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