Printhead alignment apparatus, system, and method

Abstract

To provide devices, systems, and methods for fine-tuning a printhead position and orientation.SOLUTION: A printing system includes a printhead carriage 122 supporting a printhead 124 and mounted for translation along a beam that extends along the x-axis of an x, y, z Cartesian coordinate system. A method for controlling the printing system includes sensing one or more of a rotational orientation of the printhead about the x-axis, y-axis, and the z-axis and a position of the printhead along the y-axis and z-axis. Based on the sensed one or more of the rotational orientation and the position, a position or positions of one or more bearings arranged to support the printhead carriage on the beam 116 is adjusted. Adjusting the position(s) of the one or more bearings adjusts one or both of the rotational orientation of the printhead and the position of the printhead. Systems and methods relate to control of printing systems.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 701,529, filed July 20, 2018, and U.S. Patent Application No. 16 / 515,580, filed July 18, 2019, the entire contents of each of which are incorporated herein by reference. (Field)

[0002] The present disclosure relates to devices, systems, and methods for fine-tuning the position and orientation of printheads used in industrial printing systems for manufacturing devices such as displays. [Background technology]

[0003] The manufacture of various electronic devices using inkjet printing technology relies heavily on the precision of ink droplet placement to ensure the product functions properly and meets quality expectations. Examples of these devices include, but are not limited to, microchips, printed circuit boards, solar cells, electronic displays (e.g., liquid crystal displays, organic light-emitting diode displays, quantum dot electroluminescent displays), and other devices. In an exemplary application using inkjet printing to manufacture organic light-emitting diode (OLED) displays, organic materials (also referred to as organic inks) are printed onto a substrate to form pixels. The manufacture of these and other devices presents various challenges. For example, whether using inkjet printing, thermal printing, or other techniques, it is difficult to deposit organic inks or other ink materials uniformly in desired locations with precise, accurate, and reproducible control. To achieve these goals, improvements to existing systems and technologies are needed.

[0004] As pixel size decreases with increasing resolution for display devices such as organic LED displays, the accuracy and precision of printing components, such as printheads, become increasingly important to maintaining the quality of the manufactured devices. To achieve accurate droplet placement, there is a need for various devices, systems, and methods that facilitate accurate and precise positioning and orientation of printing components, such as the position and orientation of a printhead relative to a substrate on which material is deposited. Accurate droplet placement can increase the resolution of the final product and reduce material waste during manufacturing. Additionally, there is a need for devices and methods configured to facilitate a more efficient manufacturing process and reduce (e.g., minimize) the overall complexity and weight of the associated printing equipment. Summary of the Invention

[0005] According to various exemplary embodiments of the present disclosure, a printing system includes a printhead carriage that supports a printhead and is mounted for translation along a beam that extends along an x-axis in an x-, y-, and z-axis Cartesian coordinate system. A method for controlling the printing system includes detecting one or more of the rotational orientations of the printhead about the x-, y-, and z-axes and the positions of the printhead along the y- and z-axes. Based on the detected one or more rotational orientations and positions, adjusting the positions of one or more bearings that are positioned to support the printhead carriage on the beam. Adjusting the positions of the one or more bearings adjusts one or both of the rotational orientation of the printhead and the position of the printhead.

[0006] In yet another exemplary embodiment of the present disclosure, a method for controlling a printing system includes sensing information regarding a position of a printhead along a path of movement extending in an x-axis direction; sensing information regarding one or more of a rotational orientation of the printhead about the x-axis, y-axis, and z-axis and a position of the printhead along the y-axis and z-axis; adjusting one or both of the rotational orientation and position of the printhead by adjusting the position of one or more bearings of a printhead carriage to which the printhead is mounted; and storing information correlating the positions of the one or more bearings of the printhead carriage with corresponding positions along the path of movement of the printhead carriage.

[0007] In yet another exemplary embodiment of the present disclosure, a printing system includes a substrate support system configured to support a substrate having a surface to be printed. The substrate support system is configured to maintain the surface to be printed in an x-y plane that is substantially perpendicular to the z-axis of an x-axis, y-axis, and z-axis Cartesian coordinate system. The printing system includes a beam extending across the substrate support system in the x-axis direction, and a print head carriage movably coupled to the beam and moving in the x-axis direction. The print head carriage includes one or more bearings arranged to support the print head carriage relative to the beam. At least one of the one or more bearings is coupled to a selectively adjustable actuator to adjust one or more of the rotational orientation of the print head carriage about the x-axis, y-axis, and z-axis, and the position of the print head carriage in the y-axis and z-axis directions.

[0008] Additional objects, features, and / or other advantages will be set forth in part in the description that follows, and in part will be obvious from the specification, or will be learned by practice of the present disclosure and / or claims. These objects and advantages will be realized and attained, at least in part, by the elements and combinations particularly pointed out in the appended claims.

[0009] The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the scope of the claims, which are to be entitled to their full scope, including equivalents. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a print assembly of an industrial printing system according to an exemplary embodiment of the present disclosure.

[0011] [Figure 2] FIG. 2 is a perspective view of a printhead carriage according to an exemplary embodiment of the present disclosure.

[0012] [Figure 3A] FIG. 1 is a schematic plan view of a printhead and carriage assembly according to an exemplary embodiment of the present disclosure.

[0013] [Figure 3B] FIG. 3B is a schematic plan view of the printhead and carriage assembly of FIG. 3A rotated from the orientation shown in FIG. 3A.

[0014] [Figure 4] FIG. 1 is a schematic side view of a gas bearing and actuator according to an exemplary embodiment of the present disclosure.

[0015] [Figure 5] FIG. 10 is a schematic side view of a gas bearing and actuator according to another exemplary embodiment of the present disclosure.

[0016] [Figure 6] FIG. 10 is a schematic side view of a gas bearing and actuator according to yet another exemplary embodiment of the present disclosure.

[0017] [Figure 7] FIG. 1 is a block diagram of a control system of a printing system according to an exemplary embodiment of the present disclosure.

[0018] [Figure 8] 1 is a flowchart illustrating a control method for a printing system according to an exemplary embodiment of the present disclosure.

[0019] [Figure 9] 10 is a flowchart illustrating a method for calibrating a printing system according to another embodiment of the present disclosure.

[0020] [Figure 10] 10 is a flowchart illustrating a control method for a printing system according to another embodiment of the present disclosure.

[0021] [Figure 11] FIG. 1 is a schematic perspective view of a substrate and a printhead according to an exemplary embodiment of the present disclosure.

[0022] [Figure 12] FIG. 10 is a schematic side view of a carriage and printhead relative to a beam (shown in cross section) according to another exemplary embodiment of the present disclosure.

[0023] [Figure 13] 13 is a schematic cross-sectional view of a carriage and printhead according to the exemplary embodiment of FIG. 12, taken along a plane perpendicular to the cross-section of FIG. 12.

[0024] [Figure 14] 14 is a schematic cross-sectional view of the carriage and print head according to the exemplary embodiment of FIG. 12, viewed from the same direction as FIG. 13.

[0025] [Figure 15] 13 is a schematic cross-sectional view of a carriage and print head according to the exemplary embodiment of FIG. 12, viewed from the same direction as FIG. 12. DETAILED DESCRIPTION OF THE INVENTION

[0026] Various exemplary embodiments of the present disclosure provide devices, systems, and methods for adjusting the orientation of a print head, e.g., to improve accuracy in one or both of the print head's orientation (e.g., rotation about an axis) and position (e.g., translation along an axis) relative to the surface onto which the print head deposits material. For example, various exemplary embodiments of the present disclosure enable fine adjustment of one or more of the print head's three rotational orientations about one or more of three Cartesian coordinate axes and fine adjustment of one or more of the print head's two translational positions along one or more of two Cartesian coordinate axes. For simplicity, the embodiments disclosed herein sometimes refer to adjustment of the orientation about a single rotational axis. For example, the embodiments disclosed herein relating to FIGS. 1 through 3 refer to adjustment of the print head's rotational orientation about an axis extending perpendicular to the substrate's surface to be printed (referred to herein as "θ-z" adjustment or equivalently "theta-z" adjustment). Other embodiments of the present disclosure are configured to allow rotational orientation adjustment about any or all of the Cartesian coordinate axes (x, y, z) and translational position adjustment along any two of the three Cartesian coordinate axes that are perpendicular to the direction of print head travel defined along the third Cartesian coordinate axis.

[0027] Exemplary embodiments of the present disclosure provide significant advantages over other possible methods of adjusting a printhead. For example, one possible method of adjusting the rotational orientation involves mounting the printhead on a rotating turntable that allows the printhead to rotate (e.g., spin on its own axis) about an axis perpendicular to the surface of the substrate being printed. However, this mechanism can be heavy and expensive, and its size and weight can make it difficult to integrate into an overall printing system.

[0028] As an alternative to mounting the printhead on a turntable or other rotating device, a substrate orientation adjustment device or system may be provided to adjust the angle of the substrate's printing surface relative to an axis perpendicular to the substrate's printing surface. Such a substrate orientation adjustment mechanism may, for example, be part of a substrate transport device that moves the substrate during printing. This system may be more complex than a substrate transport system not configured to provide theta-z adjustment for the orientation of the substrate's printing surface, potentially resulting in inaccuracies in other aspects of the overall substrate positioning, such as x and y positioning. Various exemplary embodiments of the present disclosure may reduce or eliminate the need to configure a substrate support system to rotate the substrate about the z-axis and compensate for movement along the x-axis. Furthermore, embodiments of the present disclosure may provide finer adjustment control with more degrees of freedom, resulting in more accurate ink placement and control.

[0029] Therefore, when embodiments of the present disclosure are used in conjunction with a substrate support system, it is not necessary for the substrate support system to rotate the substrate about the theta-z axis to correct for theta-z errors in the orientation of the print head. This reduces the complexity of the substrate support system and improves accuracy and precision. However, those skilled in the art will appreciate that various exemplary embodiments of the present disclosure may be used in conjunction with a substrate support and / or substrate transport system configured to rotate the substrate about the z axis to combine theta-z adjustment techniques for the print head and the printing surface of the substrate. For example, in exemplary embodiments, the substrate transport system may be used to provide coarse control of the orientation of the substrate, and an adjustable print head carriage may be used to provide fine control of the orientation of the print head relative to the substrate.

[0030] This disclosure contemplates various exemplary embodiments of printhead and carriage assemblies that allow the rotational orientation of the printhead relative to other components of the printing system, including the printing surface, to be rotated about one or more axes. For example, the printhead can be rotated about an axis perpendicular to the printing surface of the substrate on which the printhead deposits organic material to form pixels, allowing for relative theta-z adjustment of the printhead and the printing surface.

[0031] In an exemplary embodiment, the printhead carriage includes a plurality of bearings configured to support the printhead carriage and the attached printhead on a beam (also referred to as a gantry). These bearings may include gas bearings, magnetic levitation (maglev) bearings, or other bearings or devices that maintain the carriage at a desired position and orientation relative to the beam while reducing or minimizing contact between the beam and the carriage. For example, the bearings may be configured to translate the carriage along the beam in a single degree of freedom.

[0032] According to exemplary embodiments of the present disclosure, the position of one or more bearings can be changed relative to the carriage to change the rotational orientation of the carriage relative to the beam, and thus the orientation of the carriage relative to one or more of three Cartesian coordinate axes. For example, one or more bearings can be moved relative to the carriage along their longitudinal axis (i.e., an axis extending perpendicular to the surface of the bearing facing the beam) to change the orientation of the carriage. In some embodiments, the bearings can be attached to the carriage by passively rotating ball-and-socket joints to maintain the surface of the bearing facing the beam parallel to the surface of the beam even when the orientation of the carriage is changed.

[0033] In an exemplary embodiment, one or more bearings movable along a longitudinal axis are coupled to the carriage by an actuator. The actuator is configured to move each bearing along its longitudinal axis. The actuator may be referred to herein as an actuation mechanism. In an exemplary embodiment, the actuator comprises a piezoelectric element that changes shape based on the application of an electric current. In other exemplary embodiments, the actuator comprises a device such as, for example, a pneumatic actuator, a hydraulic actuator, or an electromechanical actuator such as a linear motor, a voice coil type device, or the like. Optionally, the actuator includes a sensor, such as a position encoder device, that provides information (e.g., a signal) containing information regarding the actual position of the actuator. This information can be used by a controller in a feedback-type control system to determine the position of the carriage.

[0034] Referring now to FIG. 1 , an exemplary embodiment of a printing system 100 applicable to industrial printing is shown. While the printing system is shown in isolation, those skilled in the art will appreciate that the printing system can be located in an enclosure with a controlled processing environment and can be part of an overall industrial system for manufacturing various electronic components, including displays (e.g., organic LED displays). Non-limiting examples of industrial systems for manufacturing electronic device components, such as display printing, are disclosed in U.S. Patent Application Publication Nos. 2014 / 0311405 A1, 2017 / 0028731 A1, 2018 / 0014411 A1, and U.S. Patent No. 9,505,245, the entire contents of each of which are incorporated herein by reference. The printing apparatus 100 includes a substrate support system 102 that supports a substrate 104. The substrate support system can include, for example, a vacuum chuck, a substrate levitation chuck with pressure and vacuum ports, or a combination thereof. In the exemplary embodiment, the substrate support system 102 includes a substrate levitation chuck 106 and a motion system 108 configured to move the substrate 104 along the y-axis shown in Figure 1. (Those skilled in the art will appreciate that the x- and y-axes of the illustrated xyz Cartesian coordinate system are interchangeable, and thus the z-axis has been selected as the axis perpendicular to the surface of the substrate to be printed, without intending to limit the scope of the present disclosure.) The motion system may include a first beam 110 and a second beam 112 arranged longitudinally along the y-axis, and a device such as a gripper (not shown) may be configured to hold the substrate 104 and move it along the y-axis within the print zone 114. Further details regarding non-limiting examples of substrate support system configurations that can be used as substrate support system 102 are described in U.S. Patent Application Publication Nos. 2017 / 0028731A1, 2014 / 0311405A1, 2018 / 0014411A1, and U.S. Patent No. 9,505,245, the contents of each of which are incorporated herein by reference.

[0035] The printing system 100 includes a beam 116 (e.g., a gantry or bridge). The beam 116 is positioned above a region of the substrate support system 102 defined as the print zone (the region below the range where the print head travels along the beam 116; more details are provided below). In the exemplary embodiment of FIG. 1 , the beam 116 is supported above the print zone by a first lift platform 118 at one end and a second lift platform 120 at the opposite end. The beam 116 may be made of a stable material that has high dimensional accuracy, rigidity, and strength. In one non-limiting example, the beam 116 has a smooth surface (e.g., a polished surface). The beam 116 may be made of a material such as, but not limited to, a ceramic material, a metal or alloy such as aluminum or steel, or a composite material. In the exemplary embodiment of FIG. 1 , the beam 116 is made of granite.

[0036] The printing system 100 may include one or more printhead carriages 122. The printhead carriages 122 are coupled to the beam 116 for translational movement along the beam 116 in the x-axis direction shown in FIG. 1 . The one or more printhead carriages 122 are configured to mount one or more printheads 124 used to deposit material on the substrate 104. For example, the one or more printheads 124 may be inkjet printheads configured to deposit ink (e.g., organic LED material) on the substrate 104. The one or more carriages 122 may be moved along the beam 116 to various positions along the x-axis to position the printheads 124 along the x-axis at desired printing locations on the substrate 104. By combining translational movement of the substrate 104 along the y-axis with translational movement of the carriage 122 along the x-axis, the printheads 124 can reach portions of the substrate 104 along the x-axis and y-axis to print organic material in desired areas of the substrate 104, thereby depositing material in a pattern on the printing surface, for example. Carriage 122 and beam 116 may be configured to maintain a printing surface (not shown) of each print head 124 parallel to the surface to be printed (the surface facing beam 116) of substrate 104. In one exemplary embodiment, printing system 100, as described above, is part of an overall industrial manufacturing system for producing electronic devices, such as substrates used in electronic displays.

[0037] The printing system 100 may also include one or more measurement devices associated with the print heads 124. For example, in the embodiment of FIG. 1, one or more sensors 119, such as interferometers, are coupled to each print head 124. The sensors 119 are coupled to optics (not shown) configured to measure the actual translational position and / or orientation of the print heads 124 and carriage 122 during a calibration process or during printing (discussed in more detail below). While only one sensor 119 is shown in FIG. 1, in an example embodiment of the printing system 100, multiple measurement devices are arranged to determine the rotational orientation of one or more print heads 124 about one or more axes, such as about the x-axis, y-axis, and z-axis. In an example embodiment, the printing system 100 includes three separate measurement devices (e.g., laser interferometers or other optical measurement devices) that measure the distance from a plane defined by the surface of the substrate 104 to three known points on the print heads. From these three distance measurements, the rotational orientation of print head 124 can be determined about all three axes (e.g., x-axis, y-axis, and z-axis). Similarly, one or more additional measurement devices can be positioned to sense the position of the print head along two axes perpendicular to the direction of travel of print head 124. For example, in the embodiment of Figure 1, the position of print head 124 relative to beam 116 along the y-axis and z-axis may be determined by additional measurement devices (e.g., optical sensors or other devices).

[0038] Additionally or alternatively, the printing system may be calibrated using a calibration device, such as a "master glass" (not shown), glass sheet, or other material that is the same size as the substrate (e.g., substrate 104). The master glass has a pattern of marks with known locations. One or more (e.g., two) high-magnification cameras are used to determine the actual positions of the marks relative to their expected locations to determine any errors in the position and / or orientation of the print head 124. Any errors are recorded and used to correct the position and / or orientation of the print head 124 using the systems and methods described herein.

[0039] Due to the high degree of precision required for printing system 100 ( FIG. 1 ), even slight inaccuracies in the components of printing system 100 can result in misalignment between one or more of print heads 124 and substrate 104 as print head carriage 122 moves along beam 116 to print. For example, minute irregularities in the surface of beam 116 due to manufacturing tolerances in the manufacture of beam 116 can cause variations in the rotational orientation of carriage 122 about the z-axis (shown in FIG. 1 ) as carriage 122 moves along beam 116. For example, variations in the thickness or flatness of beam 116 can cause variations in the rotational orientation of carriage 122 about the z-axis as carriage 122 moves along beam 116. Even small variations in these orientations (e.g., on the order of microradians) can result in variations in the predicted position of print head 124 relative to substrate 104, potentially compromising printing accuracy (e.g., intended drop placement and / or trajectory). For example, the orientation of the printhead face, from which the ink-depositing nozzles extend, relative to the surface of the substrate being printed may be misaligned in theta-z, which can lead to both inaccurate placement of ink droplets and / or uneven deposition and therefore drying of ink droplets, resulting in uneven film thickness in the final product.

[0040] In addition to variations in the carriage 122's orientation about the z-axis, variations in the thickness or flatness of the beam 116 can also cause variations in the carriage 122's orientation or position about other axes as the carriage 122 moves along the beam 116. For example, some sagging of the beam 116 can occur between the first and second lift platforms 118, 120 because the beam 116 is not supported along its entire length. The sagging of the beam 116 can cause variations in the carriage 122's rotational orientation about the y-axis as the carriage 122 moves along the beam 116. The rotational misorientation about the y-axis can cause the print head surface to be non-parallel to the substrate's printing surface. Such sagging can also cause the print head surface to be closer to the substrate's printing surface than intended or designed. Similarly, variations in beam thickness, flatness, and straightness can cause variations in the rotational orientation of carriage 122 about the x- and y-axes, in addition to the aforementioned variations about the z-axis. Similarly, the aforementioned variations in the beam and / or other component supports throughout the system can cause variations (translations) in the position of carriage 122 along the y- and z-axes. Example embodiments of the present disclosure can be configured to compensate for (e.g., correct) variations in the orientation of carriage 122, and thus printhead 124, about the x-, y-, and z-axes, as well as to compensate for the position of carriage 122 along two independent axes perpendicular to the direction of carriage 122 movement (e.g., the y- and z-axes in FIG. 1 ).

[0041] 11, there is shown a schematic perspective view of a substrate 1104. FIG. 11 illustrates the changes in orientation about the x-, y-, and z-axes (θ-x, θ-y, and θ-z, respectively) and translations along the x-, y-, and z-axes (x-, θ-y, and θ-z, respectively). T , y T , z T In an exemplary embodiment of the present disclosure, the translation x T represents the movement of print head 1124 along a path of movement such as beam 116 (FIG. 1).

[0042] FIG. 11 also illustrates that potential misalignment of the substrate position or orientation can result in misalignment between the print head and the substrate. In FIG. 11, solid lines indicate the substrate 1104 in a first orientation. Dashed lines indicate the substrate 1104 in a second orientation, rotated relative to the first orientation about one of the x-axis, y-axis, or z-axis. The substrate 1104 can also be misaligned translationally relative to the print head 1124 in either the x-axis, y-axis, or z-axis. Such rotation or translation of the substrate 1104 can result in misalignment between the substrate 1104 and the print head 1124. Additionally, or alternatively, misalignment between the substrate 1104 and the print head 1124 can result from rotational misalignment of the print head 1124 relative to the substrate 1104. The total misalignment between the print head 1124 and the substrate 1104 can be the sum of the deviations of the substrate 1104 from its intended orientation about the x-, y-, and z-axes and from its intended position in the x-, y-, and z-directions, and the deviations of the print head 1124 from its intended orientation about the x-, y-, and z-axes and from its intended position in the y- and z-directions (the x-direction being the direction of travel of the print head 1124). In the exemplary embodiment of the present disclosure described with respect to Figures 2-10, the carriage 122 (Figure 1) and the print head 124 (Figure 1) can be adjusted rotationally and translationally along each axis to compensate for such deviations from the intended alignment of the print head 124 with the substrate 104.

[0043] Referring now to FIG. 2 , a printhead carriage 222 according to an exemplary embodiment of the present disclosure is shown in more detail. The printhead carriage 222 can include one or more devices configured to facilitate low-friction movement of the printhead carriage 222 along a beam, such as beam 116 in FIG. 1 , and to facilitate accurate positioning of the carriage 222 relative to the surface of a substrate to be printed. In an exemplary embodiment, the printhead carriage 222 includes features configured to support the carriage 222 and enable it to move along the beam 116 while minimizing (e.g., reducing or eliminating) friction between the carriage 222 and the beam 116. The carriage 222 includes a printhead mount 223 configured to receive a portion of a printhead (e.g., printhead 124 shown in FIG. 1 ) and hold the printhead in place on the carriage 222 as the carriage 222 traverses the beam 116.

[0044] 2, printhead carriage 222 includes a plurality of gas bearings 226. Each gas bearing 226 has a surface 229 that faces a beam (e.g., beam 116 shown in FIG. 1), and gas bearings 226 are configured to receive a supply of pressurized gas (e.g., air or an inert gas) and to vent the gas between the beam and surface 229 of gas bearing 226, thereby creating a layer of air or other gas that supports carriage 222 against the beam.

[0045] 2-4, other exemplary embodiments may include other types of devices configured to reduce (e.g., eliminate) contact friction between the printhead carriage and the beam. For example, some exemplary embodiments may include various combinations of permanent magnets and / or electromagnets configured to levitate the carriage 222 relative to the beam 116 using magnetic forces. Such devices are also referred to as "maglev" devices.

[0046] Each gas bearing 226 may be pivotally coupled to carriage 222. The pivotal nature of the gas bearings 226 facilitates aligning surfaces 229 of the gas bearings 226 parallel to the surface of the beam 116 they face. In other words, the pivotal coupling allows surfaces 229 of the gas bearings 226 to be positioned horizontally relative to the surface of the beam 116. Positioning the gas bearings 226 in this manner facilitates proper operation of the gas bearings 226, i.e., the formation of a gas cushion between the gas bearings 226 and the beam 116. In the exemplary embodiment, as shown in FIG. 4 , the gas bearings 226 are coupled to carriage 222 using ball-and-socket joints 434. Therefore, the ball-and-socket joints 434 facilitate "self-alignment" of the gas bearings 226 relative to the beam 116. Each gas bearing 226 may be "self-aligning" independently of the other gas bearings 226. In the embodiment described herein, a ball joint 434 is shown, however, other articulated assemblies, such as assemblies including one or more rotational bearings, are within the scope of the present disclosure.

[0047] In an exemplary embodiment of the present disclosure, one or more gas bearings are aligned along a longitudinal axis A of the bearing. L As used herein, the "longitudinal axis" of a gas bearing refers to an axis perpendicular to the surface 229 of the gas bearing. For example, as shown in FIG. 2, adjusting gas bearing 226A is coupled to carriage 222 so as to be movable along longitudinal axis A. L . In other words, the bearing surface 229 of the regulating gas bearing 226A can translate to protrude away from or approach the surface of the mounted printhead carriage 222. The gas bearing 226A is sometimes referred to as the "regulating gas bearing 226A" or the "translating gas bearing 226A." As the regulating gas bearing 226A moves along its longitudinal axis, the orientation of the carriage 222 relative to the beam 116 also changes.

[0048] While the exemplary embodiment of Figure 2 shows two regulating gas bearings 226A at upper and lower positions on one side of the carriage 222, other exemplary embodiments may include one regulating gas bearing or more than two regulating gas bearings 226A. For example, the exemplary embodiment includes four regulating gas bearings at four positions adjacent to the printhead mount 223 of the printhead carriage. Additionally or alternatively, the carriage 222 may include additional gas bearings located at positions other than those shown in Figure 2, such as, but not limited to, one or more regulating gas bearings 226A at six, eight, or more gas bearing positions adjacent to the printhead mount 223.

[0049] Gas bearing 226C, mounted on carriage 222 opposite adjusting gas bearing 226A, is configured to passively move longitudinally to compensate for the longitudinal movement of adjusting gas bearing 226A. That is, because the thickness T (FIG. 1) of beam 116 is nominally constant, a longitudinal change in the position of adjusting gas bearing 226A results in longitudinal movement of gas bearing 226C opposite adjusting gas bearing 226A. Thus, the distance between gas bearing 226C and adjusting gas bearing 226A remains constant, allowing gas to flow from the bearings through the gap between gas bearings 226A, 226C, and beam 116, ensuring proper function of gas bearing 226.

[0050] 2, gas bearing 226C (also referred to as a compensating gas bearing) is coupled to carriage 222 using spring struts 234 that allow longitudinal movement of compensating gas bearing 226C to compensate for longitudinal movement of adjusting gas bearing 226A. Spring struts 234 can be comprised of mechanical springs such as coil springs, disc springs, leaf springs, etc., which may be made of a resilient material such as a metal alloy, polymer, or other material, or may comprise a gas spring or other type of spring member, such as a variable volume pneumatic reservoir.

[0051] An exemplary embodiment that only performs a theta-z adjustment will be used to explain various principles of operation. Other orientation / position adjustments will then be described based on the same general principles. In use, to compensate for variations in the orientation of the carriage 122, and therefore the print head 124, relative to the substrate 104 (FIG. 1), the adjustment gas bearing 226A can be moved along its longitudinal axis to return the orientation of the carriage 122 to a desired theta-z orientation, for example, relative to the printed surface of the substrate, as will be further described in connection with FIGS. 3A and 3B.

[0052] 3A and 3B, there are shown schematic plan views of a printhead carriage 322 and a portion of beam 316 of a printing system (e.g., printing system 100 shown in FIG. 1). Figures 3A and 3B are views looking down on a substrate's surface, such as substrate surface 305 of substrate 304, from a direction perpendicular to the substrate's surface, as shown by the dashed line. In the configuration shown in FIG. 3A, tuning gas bearing 326A is in a neutral position relative to carriage 322, and printhead 324 is in a neutral orientation relative to substrate 304.

[0053] FIG. 3B is a schematic plan view similar to that shown in FIG. 3A, but shows that the adjusting gas bearing 326A is aligned with the longitudinal axis A relative to the carriage 322. L(Only one is shown in Figures 3A and 3B, the other is located below the visible one). Extension of tuning gas bearing 326A causes the carriage's orientation about the z-axis (an axis perpendicular to the plane of the paper in Figures 3A and 3B) to change in a clockwise rotational direction, as shown by arrow C in Figure 3B. Because changing the orientation of carriage 322 about the z-axis can change the y-axis position of print head 324 relative to substrate 304 (i.e., its vertical position in Figures 3A and 3B), the control system of printing system 100 (Figure 1) may be further configured to adjust the y-axis position of substrate 304 to compensate for the change in position of print head 324 and substrate 304 in the y-axis. Similarly, a change in the orientation of carriage 322 about the z-axis results in a change in the position of carriage 322 along the x-axis (i.e., a change in position along the direction of beam 316), which can be compensated for by moving carriage 322 along beam 316.

[0054] While the exemplary embodiment of Figures 2-3B includes two adjusting gas bearings (e.g., 226A in Figure 2, one of which (326A) is shown in Figure 3B), other embodiments may optionally have only one adjusting gas bearing or more than two. For example, in one exemplary embodiment, the bearing diagonally opposite the adjusting gas bearing (i.e., the bearing in the upper left of Figures 3A and 3B) expands in the same manner as the adjusting gas bearing. As an additional non-limiting example, rather than using the compensating bearing 326C shown in Figures 3A and 3B, the gas bearings 326 and 326C in Figures 3A and 3B may be selectively expanded and contracted relative to the carriage 322 to actively compensate for the expansion of the adjusting gas bearing 326A.

[0055] As adjusting gas bearing 326A and compensating bearing 326C move relative to the carriage, changing the orientation of carriage 322 relative to beam 316, the rotational orientation of carriage 322 about the z-axis changes, as shown in Figure 3B. The ball joints of gas bearing 326, adjusting gas bearing 326A, and compensating bearing 326C adjust to keep surfaces 329 of gas bearings 326, 326A, and 326C parallel to the surface of beam 316. Thus, gas bearings 326, 326A, and 326C can maintain a low-friction (e.g., low-friction or no-friction) interface between beam 316 and carriage 322 in the orientation shown in Figure 3B. In other words, the ball joints passively adjust the surfaces 329 of the gas bearings 326, 326A, 326C to ensure that they are level with the surface of the beam 316, facilitating the formation of a gas cushion (e.g., a gas layer) between the surfaces 329 of the gas bearings 326, 326A, 326C and the surface of the beam 316.

[0056] In the exemplary embodiment of FIG. 4, the regulating gas bearing 426A is coupled to the printhead carriage 422 by a piezoelectric actuator 436 (FIG. 4). The piezoelectric actuator 436 is configured to change shape based on the application of an electric current. In the exemplary embodiment of FIG. 4, application of an electric current to the piezoelectric actuator 436 causes the regulating gas bearing 426A to expand, moving away from the surface of the carriage 422 to which the piezoelectric actuator 436 is connected. For example, application of an electric current can cause the piezoelectric actuator 436 to change from a first, unextended (e.g., contracted) state 438, shown in solid lines, to a second, extended state 440, shown in dotted lines. The application of the electric current can be controlled, for example, by a control system that controls movement of the carriage 422 along the x-axis along the beam (e.g., beam 116, 216, or 316 shown in FIGS. 1-3B) and movement of the substrate (e.g., substrate 104 shown in FIG. 1 or substrate 304 shown in FIGS. 3A and 3B) along the y-axis.

[0057] Piezoelectric components can provide desirable characteristics for actuator 436, including, but not limited to, high compression, high precision, and relatively small movement. For a beam (e.g., beam 116, 216, or 316 shown in FIGS. 1-3B ) to withstand the forces exerted by the gas bearings (which may be on the order of thousands of Newtons (N)), a high compression force must be exerted by actuator 436. For example, the force exerted by the gas bearings on the beam can range from approximately 500 N (113 pounds of force) to approximately 1500 N (337 pounds of force). The force exerted by the gas bearings on the beam can be greater than or less than the exemplary ranges shown above, e.g., less than 500 N or greater than 1500 N, depending on factors such as the number of gas bearings, the area of ​​the bearing surfaces, and the weight of the printhead and carriage assembly.

[0058] The desired range of rotation of the printhead carriage about the z-axis (or x-axis or y-axis, if applicable) can be less than 1 radian and can be expressed in microradians. In an exemplary embodiment, the range required to rotate the printhead carriage about a selected axis to correct misalignment can be 0 microradians to 50 microradians, 0 microradians to 100 microradians, or other ranges. To facilitate rotation over this range, an actuator (e.g., actuator 436 shown in FIG. 4 ) may need to translate the tuning gas bearings a distance in the micron range, for example, from about 0 microns to about 100 microns. This distance varies depending on the pitch between the tuning gas bearings (i.e., the distance between the tuning gas bearings) and the desired change in rotational orientation of the printhead carriage about the selected axis.

[0059] For example, the pitch between the tuning gas bearings may be about 0.5 meters (19.7 inches), and the range of travel of the tuning gas bearings may be about 25 microns, which may result in a maximum rotation of the carriage about the selected axis of about 50 microradians. In other exemplary embodiments, the range of orientation change about the selected axis required to properly orient the printhead carriage relative to the printing surface of the substrate may be less than or greater than 50 microradians, and the range of longitudinal travel of the tuning gas bearings along their longitudinal axes will vary accordingly.

[0060] Actuators other than piezoelectric actuators are also contemplated within the scope of the present disclosure. For example, in certain exemplary embodiments, the regulating gas bearings may be actuated by an electromechanical device, such as a hydraulic device, a pneumatic device, a linear motor, or a stepper motor, connected to a kinematic linkage, or any other device configured to longitudinally move the bearing based on an electrical or other control signal. As a further non-limiting exemplary embodiment, one or more actuators may comprise a voice coil-type device including a magnet and a movable electromagnet, for example, comprising a coil of wire wound around a bobbin. Applying a current to the coil generates a magnetic field that interacts with the magnetic field of the magnet, causing movement of the bobbin. Details of this device are described in U.S. Patent Application Publication No. 2018 / 0014411 A1, the contents of which are incorporated herein by reference.

[0061] In the exemplary embodiment of Figure 4, the carriage 422 and tuning gas bearing 426A may include a mechanical (i.e., "hard") stop 442 that limits movement of the tuning gas bearing 426A relative to the carriage 422. This stop 442 ensures that a coupled printing system (e.g., printing system 100 shown in Figure 1) can function properly even when the tuning gas bearing 426A is in its fully extended tuning position. In the embodiment of Figure 4, the tuning gas bearing 426A is shown adjacent to the beam 416. While the mechanical stop 442 is specifically shown and described with respect to Figure 4, the mechanical stop 442 may be included in any of the exemplary embodiments described herein.

[0062] In the exemplary embodiment of FIG. 4 , the mechanical stop 442 includes one or more annular members 443 disposed on either side of a shoulder 445 disposed on the actuator. The annular members 443 contact the shoulder 445 to prevent the adjustment gas bearing 426A from overextending or underextending beyond the adjustable range defined by the shoulder 445 and the annular members 443. The adjustable range can be selected based on the amount of extension required to correct the carriage orientation. For example, in the exemplary embodiment, the adjustment bearing may have an adjustment range of approximately 25 microns, as described above. Other exemplary embodiments may have a wider adjustment range, such as 50 microns, 100 microns, or more, or a narrower adjustment range, such as 10 microns, 5 microns, or less. The mechanical stop 442 limits the actuator's range of motion to a range where the actuator provides predictable and stable movement for a given electrical input. For example, the actuator's range of motion may be limited to a range where the relationship between applied current and actuator movement is approximately linear. Additionally, the mechanical stops 442 can maintain the actuator and carriage positions within defined limits when the actuator is not powered, such as when the printing system is powered down for maintenance or during periods of non-use.

[0063] In yet another exemplary embodiment, the actuator may include one or more piezoelectric actuators coupled between the regulating gas bearings in parallel with another device configured to support at least a portion of the load applied between the regulating gas bearings and the carriage. This device may be, for example, a resilient biasing member such as a mechanical spring or a pneumatic spring. For example, referring now to FIG. 5, a schematic side view of the regulating gas bearing 526A and the carriage 522 is shown. A spring 546 (e.g., a coil spring) is coupled between the regulating gas bearing 526A and the carriage 522. The spring 546 is mounted in parallel with an actuator (e.g., a piezoelectric actuator) 536. The spring 546 can support a portion of the load applied between the regulating gas bearing 526A and the carriage 522, and the piezoelectric actuator 536 can finely position the carriage 522 relative to the regulating gas bearing 526A as described above. For example, the load is the force exerted by the weight of a printhead (not shown in FIG. 5) supported by carriage 522 and at least a portion of the weight of carriage 522 itself.

[0064] Referring now to Figure 6, a similar configuration to that described with respect to Figure 5 is shown. In Figure 6, instead of coil spring 546, a pneumatic spring 647 (e.g., including a piston-cylinder arrangement) is positioned in parallel with piezoelectric actuator 636 between regulating gas bearing 626A and carriage 622. Pneumatic spring 647 supports a portion of the load applied between regulating gas bearing 626A and carriage 622, and piezoelectric actuator 636 can finely position carriage 622 relative to regulating gas bearing 626A.

[0065] During use, a printhead carriage (e.g., printhead carriage 122, 222, 322, or 422) can be moved along a beam (e.g., beam 116, 316, or 416 shown in Figures 1-3B) by a linear motor system. The linear motor system includes a stator (not shown) connected to the carriage 422 and a series of permanent magnets or electromagnets (not shown) embedded or otherwise affixed to the beam. Extending the regulating gas bearing 426A beyond a certain range can affect the alignment of the stator with the magnets, and therefore the stator can affect the magnets or the beam. A mechanical stop 442 can prevent the regulating gas bearing 426A from extending beyond a certain distance where the linear motor functions properly and the carriage 422 does not affect the beam. While a mechanical stop is specifically shown in the embodiment of Figure 4, a mechanical stop may be used in any of the other embodiments or combinations of embodiments shown in this disclosure.

[0066] In an exemplary embodiment, the printing system may incorporate a system for correcting deviations of a substrate transport system, such as the substrate support system 102 (FIG. 1), from an intended transport path. The correction system may be generally as described in U.S. Patent Application Publication No. 2018 / 0014411 A1 or U.S. Patent No. 9,505,245, issued November 29, 2016, the entire contents of which are incorporated herein by reference. The system may also include a transport system, such as a substrate gripper, configured to guide a component, such as a substrate, along a transport path as a manufacturing aid. In a typical implementation, the transport path may be on the order of several meters, but positioning may be required on a micron or finer scale (e.g., nanometer or finer). To aid in precise positioning, one or more sensors are used to detect one or more dimensions of the misalignment between the component (e.g., substrate) and the light beam. A position correction signal is then generated based on the deviation detected by the one or more sensors. This signal is provided to one or more transducers and used to offset the deviation. This allows the part to follow the optical path without being hindered by small mechanical errors along the transport path. In an exemplary embodiment, one or more sensors provide feedback so that the transducer constantly "zeroes out" positional and / or rotational errors.

[0067] In exemplary embodiments of the present disclosure, one or more aspects of the path-compensating transport system may be used in conjunction with an adjustable printhead carriage (e.g., printhead carriage 122, 222, 322, 422, 522, 622, or 1222). A printhead carriage configured to provide rotational adjustment about and positional adjustment along each axis, combined with the path compensation provided by embodiments disclosed in U.S. Patent Application Publication No. 2018 / 0014411 A1 or U.S. Patent No. 9,505,245, can improve printhead-to-substrate positioning accuracy and ensure precise, accurate, and repeatable print results. Furthermore, printhead carriage rotational and positional adjustment can reduce or eliminate the need for substrate rotational adjustments via the transport system, reducing the number and associated complexity of the transport system. Thus, by perfectly aligning the substrate and printhead, both transport path errors (deviations from the intended transport path) and rotational or positional errors (e.g., printhead theta-z errors or other deviations from the intended rotational alignment or position) can be corrected as needed to achieve accurate printing results.

[0068] Embodiments of the present disclosure may include a control system configured to rotate or translate the carriage (e.g., carriage 122, 222, 322, 422, 522, 622, or 1222) as needed to correct for rotational or positional inaccuracies due to deviations in the straightness and / or flatness of components associated with the beam 116 or the substrate support system 102. The control system may include one or more sensors configured to determine the actual position and orientation of the carriage and substrate transport system, and one or more processors operably coupled to the one or more sensors. In exemplary embodiments of the present disclosure, the one or more sensors may include one or more components such as an encoder, an interferometer (e.g., a laser interferometer), or other optical measurement devices such as a camera. The control system may be an integrated control system that controls both the print head carriage and the transport system, or it may include two substantially separate control systems that independently control the substrate transport system and the print head carriage.

[0069] In an exemplary embodiment, a desired position or rotational orientation of the printhead carriage relative to a particular axis of rotation, or a desired amount by which the carriage position and / or orientation must be adjusted to compensate for the misalignment, is determined based on information about the actual position and orientation of the printhead carriage as it translates along the x-axis along the beam. In an exemplary embodiment, a measurement device on the printhead (e.g., printhead 124, 324 shown in FIGS. 1, 3A, and 3B) is used to determine the misalignment or position inaccuracy that occurs as the printhead carriage moves along the beam as it moves along the beam. For example, one or more of a camera, an interferometer such as a laser interferometer, or other measurement devices such as those described above can be used to collect information about the orientation and position of the printhead as the carriage moves along the beam. The orientation and position data can be provided to a control system. The control system controls the position of the printhead carriage (printhead carriage 122, 222, 322, 422, 522, 622, or 1222), the y-position of the substrate (e.g., substrate 104, 304 shown in Figures 1, 3A, and 3B), and one or more rotational orientations of the printhead carriage (and thus the printheads mounted on the printhead carriage) about one or more rotational axes (e.g., the theta-z orientation of the printhead carriage). The control system may also perform other control functions for printing system 100, such as controlling the loading and unloading of substrates and the deposition of organic material through the printheads.

[0070] Additionally, the center of rotation of the printhead about any of the x, y, or z axes may be offset from the center of the printhead, and therefore, rotational orientation of the carriage about an axis may cause the printhead to move in the x, y, or z directions. The control system may be programmed or otherwise configured to compensate for such movement and move the carriage or substrate an appropriate amount based on the rotational adjustment about the x, y, and / or z axes.

[0071] In an example embodiment, the control system may operate on a "real-time" basis, collecting and processing data regarding the actual position and / or orientation of the substrate or carriage being carried by the transport system as the print head carriage moves along the beam 116, 316, 416, 1216. The control system may then process the real-time data and adjust the position and / or orientation of the transport system or print head carriage to compensate for any inaccuracies in the transport system or carriage orientation or position during a printing operation.

[0072] As an alternative to a “real-time” control configuration, in various exemplary embodiments, the control system may record, during the initial calibration process, the carriage movements required to compensate for any inaccuracies in the beam through which the carriage moves. The required corrections to the carriage orientation may be calculated based on measurements taken by one or more sensors, such as an interferometer or other measurement device, as the carriage moves back and forth along the beam. The measurements may be collected in a correction table or map associated with the carriage's position along the beam. Each correction value is associated with a specific carriage position by the table or map, and this set of correction values ​​is used to compensate for specific inaccuracies in the beam, such as variations in beam flatness or thickness. The correction table or map is associated with the specific beam used in the printing system for which the calibration was performed. The correction values ​​may be stored in electronic memory operably coupled to the control system's processor. The control system applies a correction value associated with each position of the carriage on the beam or each position of the transport system along the transport path, so that inaccuracies in the position and / or orientation of the carriage and transport system do not have to be re-measured each time the carriage moves back and forth along the beam and the transport system moves along the transport path.

[0073] Referring now to FIG. 7 , a block diagram illustrating a control system 750 for controlling a printing system according to an exemplary embodiment of the present disclosure is shown. The control system 750 includes at least one sensor device 752 configured to generate an output signal representative of the orientation and / or position of a print head (e.g., print head 124, 324, 1224 of FIGS. 1 , 3A, 3B, 12-15 ) relative to a surface of a substrate to be printed, onto which the print head is configured to deposit a material, such as ink. The sensor device 752 may include one or more sensors, such as interferometers, encoders, or other devices described herein and / or known to those skilled in the art. In one embodiment, the sensor device 752 includes one or more laser interferometers.

[0074] The sensor device 752 is operably coupled to a controller 754, such as a computer system including a processor and electronic storage media. The controller 754 receives information from the sensor device 752 regarding the rotational orientation and / or position of the print head relative to the surface being printed. Additionally, in some embodiments, the controller 754 may receive information from other devices, such as other sensors coupled to the printing system. These sensors are configured to generate information regarding the rotational orientation and position of the print head in the x, y, and z directions (e.g., along the x, y, and z axes described for the exemplary embodiment with respect to Figures 1-4 above). Additionally or alternatively, the controller 754 may receive information from other devices and systems in the printing system, such as a system configured to support and / or transport a substrate (e.g., the substrate support system 102 shown in Figure 1) or a system configured to move the print head (e.g., the motion system 108 shown in Figure 1). The controller 754 may receive inputs regarding operational aspects of the printing system, such as printhead position, substrate position, operating conditions of the printing system, information related to other components of the printing system such as the containment plenum, or other inputs.

[0075] The controller 754 may be operatively coupled to various components of the printing system, such as the substrate support system (e.g., 102 in FIG. 1 ), the motion control system (e.g., 108 in FIG. 1 ), or other components of the printing system. The controller 754 may generate output signals to control the printing system based on input from the sensor device 752 and input from any other sensors or input devices operatively connected to the controller 754. For example, the controller 754 may be configured to send output signals to one or more control devices 756 of the printing system. The control devices 756 may include, for example, controllable components (e.g., motors, servo motors, linear motors, or other actuators) coupled to components of the printing system.

[0076] In the exemplary embodiment of FIG. 7, controller 754 sends output signals to a control device 756. Controller 756 includes, for example, one or more actuators (e.g., piezoelectric actuators 436 shown in FIG. 4) configured to change position and / or shape based on an applied current. In this manner, the output signals from controller 754 can be used to control the actuation state of actuators 436 and the orientation of the corresponding print heads (e.g., print heads 124, 324 of FIGS. 1 and 3A / 3B). Additionally, in the exemplary embodiment, controller 754 may generate additional outputs that control the operational state of the printing system, such as by controlling a substrate support system, a motion control system, or other operational aspects of the printing system.

[0077] In an exemplary embodiment, control device 756 optionally includes a device configured to provide feedback to controller 754. For example, in an exemplary embodiment, control device 756 is a piezoelectric actuator coupled to encoder device 757 configured to provide feedback to controller 754 regarding the actual position of control device 756. Encoder device 757 may be an optical encoder, a magnetic encoder, or any other device configured to generate a signal based on the position or movement of control device 756. If control device 756 reaches a target position based on the received feedback, controller 754 maintains the control device at the target position. When feedback from encoder device 757 indicates that control device 756 has reached the target position, controller 754 stops movement of control device 756.

[0078] Referring now to FIG. 8 , a flowchart 860 illustrates a workflow for adjusting the axial position and / or axial orientation of a printhead carriage. Throughout this specification, the term “position” refers to translational position along an axis, and the term “orientation” refers to rotational orientation about an axis. The exemplary embodiment of FIG. 8 represents an example of a control method that uses real-time input regarding the actual position and / or orientation of the carriage and adjusts the carriage position and / or orientation based on the real-time input. At 862, the workflow includes sensing information regarding the rotational orientation of the printhead about an axis perpendicular to the printing surface onto which the printhead deposits material. The printhead may be attached to a printhead carriage that is movably mounted on a beam that extends across the substrate support system. In various exemplary embodiments, the sensed printhead orientation information can be provided to a controller, such as controller 754 ( FIG. 7 ).

[0079] At 864, one or both of the axial position and rotational orientation of the printhead carriage are adjusted, e.g., based on the sensed information. As described above, in exemplary embodiments, this adjustment can be achieved by adjusting the orientation of the printhead relative to the substrate about an axis perpendicular to the substrate's surface to be printed by changing the size, shape, position, or other characteristics of one or more actuators, such as actuator 436 (FIG. 4). For example, as described above with respect to FIGS. 1-4, one or more non-contact bearings, such as gas bearings 226, 326, and 426 (FIGS. 2, 3A, 3B, 4), may be moved by the actuators along their respective longitudinal axes to change the orientation of the printhead. In various exemplary embodiments, the actuators may be controlled by a controller, such as controller 754 (FIG. 7). For example, the controller may receive the sensed information and output a signal to control the actuator to adjust the printhead carriage.

[0080] At 866, the actual orientation of the printhead carriage about the axis and / or the actual position along the axis may be sensed, and further control or adjustment may be performed as needed based on the actual orientation and position, or the orientation and position may be confirmed and the adjustment may be stopped. For example, in an exemplary embodiment, the controller receives signals from one or both of an encoder (e.g., encoder device 757 in FIG. 7) or another measurement device, such as sensor device 752 (FIG. 7). The encoder or another measurement device may sense one or more of the actuator position, bearing position, or carriage position, and provide the sensed information to the controller as a signal indicating the actual position of the sensed component. The controller evaluates the received signals and determines the actual orientation and position of the carriage based on, for example, stored geometric relationships correlating the position of each component, such as the actuator and / or bearing, with the actual orientation and / or position of the carriage. Based on the information received by the controller, if the carriage is not at the desired orientation and / or position, the controller may further adjust the orientation and / or position of the carriage until the signals received from the encoder or sensor indicate the orientation and / or position is correct. 3A and 3B, for example, correction of the theta-z orientation of the carriage can result in changes in the x and y position of the print head relative to the substrate. The controller may be configured to adjust the x and y positions of the print head as needed based on changes in the print head's orientation about the z axis. Similarly, changes in rotational orientation about the x or y axes can result in changes in translational position along the x, y, and z axes, and the controller may be programmed to correct for such changes in position based on information from one or more sensors.

[0081] As an alternative to the real-time control method described above with respect to Figure 8, in one exemplary embodiment, the control system may be programmed with information from an initial calibration process, and the information obtained during the initial calibration process is used by the controller to control the orientation of the carriage during subsequent printing operations. In one example of this configuration, the measurement device used to determine the orientation of the carriage as it moves along the beam is only temporarily attached to a component of the printing system for calibration purposes and can then be removed from the printing system once the calibration process is complete. Such a configuration therefore reduces the cost and overall complexity of the printing system because the measurement system does not need to be permanently attached to the printing system.

[0082] Referring now to FIG. 9 , another exemplary embodiment of workflow 970 includes an initial calibration process using one or more measurement devices, where these one or more measurement components, after their use in the initial calibration process, do not need to be used in subsequent printing operations. For example, at 972, workflow 970 includes detecting information regarding one or both of the rotational orientation and position of the print head relative to a surface onto which the print head is depositing material. Detection can be performed by a measurement device, such as an interferometer or camera, as described above. In various exemplary embodiments, measurement information from the measurement device regarding the orientation and position of the print head is received by a controller as the print head carriage moves along a path of travel, such as beam 116, 316, 416. At 974, the orientation and / or position of the print head is adjusted as the print head moves along the path of travel. For example, in various exemplary embodiments, the controller sends signals to one or more actuators to adjust the rotational orientation or position of the carriage and print head until information from the measurement device indicates that the desired orientation and / or position of the print head has been achieved. Optionally, a sensor, such as an encoder, coupled to the actuator provides a signal to the controller containing information about the actual position (e.g., linear extension) of the actuator relative to the carriage. Another sensor may provide the controller with information about the position of the carriage and print head along a path of movement, such as along the beam. Additional adjustments to the position and / or orientation of the print head may be made as needed based on changes in the orientation or position of the print head resulting from adjustments by one or more actuators.

[0083] At 976, information regarding the rotational orientation of the print head and its position along and perpendicular to the path of travel is stored to collect a set of correction values ​​corresponding to the positions along the path of travel of the print head. For example, in various exemplary embodiments, the controller associates information regarding the positions of one or more actuators with the position of the carriage along the beam to collect a set of actuator positions associated with the position of the carriage along the beam. This set of collected information can optionally include x-, y-, and z-direction correction values ​​for a given position of the carriage along the beam, as needed, to compensate for changes resulting from rotation of the carriage about a given axis. The associated set of collected values, referred to as a table, list, map, etc., can be stored in electronic memory operatively coupled to the processor. Electronic memory includes, but is not limited to, random access memory (RAM), read-only memory (ROM), electronic storage devices such as disk drives or flash memory, or any other type of electronic storage medium or device.

[0084] When the printing system is used after the initial calibration process, the orientation and / or position of the carriage and print head are adjusted by the controller based on the carriage's position along the beam. This adjustment is made by controlling one or more actuators on the carriage according to an actuator extension value associated with the carriage's position as the carriage moves across the beam. For example, referring now to FIG. 10 , workflow 1080 is shown. At 1082, information regarding the position along the print head's path of travel is sensed. For example, in various exemplary embodiments, during a printing operation, the controller receives information regarding the carriage's position along the beam. At 1084, the rotational orientation and / or position of the print head is adjusted based on stored correction values ​​corresponding to the position along the print head's path of travel. For example, in various exemplary embodiments, the controller may adjust the carriage's orientation or position based on values ​​stored in electronic memory, such as data stored in connection with step 976 of the workflow of FIG. 9 . In this way, the control system can correct for orientation and position errors based on an initial calibration rather than relying on real-time measurements, thereby reducing the need to integrate measurement sensors and systems into the printing system and, as a result, reducing the complexity of the printing system.

[0085] 12-15 are schematic diagrams illustrating the use of one or more actuators on the carriage to adjust the carriage's orientation about the x-axis and y-axis (the coordinate system of FIG. 1 ). In the exemplary embodiment described above, only two of the gas bearings 226 are adjustable gas bearings and are configured to adjust the carriage's orientation about the z-axis; however, in other exemplary embodiments, the system may include more than two adjustable gas bearings to facilitate adjustment of the carriage's orientation about and / or position along other axes. In some exemplary embodiments, each of the gas bearings may be an adjustable gas bearing because it is attached to an actuator. The number of gas bearings may be adjustable based on the number of individual adjustments desired; increasing the number of desired adjustments simply requires providing more gas bearings on the actuator.

[0086] Referring now to FIG. 12 , a cross-sectional view of the beam 1216, carriage 1222, and print head 1224 is shown taken along a plane perpendicular to the length of the beam 1216. In the orientation of the drawing in FIG. 12 , the x-axis is an axis perpendicular to the plane of the drawing. To rotate the carriage 1222 about the x-axis, actuators coupled to adjustable bearings 1286 and 1287 are actuated to increase the distance between the carriage 1222 and the surface of each adjustable bearing 1286 and 1287 facing the beam 1216. An actuator coupled to adjustable bearing 1288 is actuated to decrease the distance between the carriage 1222 and the surface of adjustable bearing 1288 facing the beam 1216. As a result, the carriage 1222 and the associated print head 1224 rotate counterclockwise about the x-axis, as indicated by arrow R in FIG. 12 . When it is desired to rotate the carriage 1222 and print head 1224 clockwise about the x-axis, actuators coupled to the adjustable bearings 1286, 1287 are actuated to decrease the distance between the carriage 1222 and the surfaces of the adjustable bearings 1286, 1287 that face the beam 1216. Additionally, the adjustable bearing 1288 is actuated to increase the distance between the carriage 1222 and the surfaces of the adjustable bearings 1288 that face the beam 1216. In this manner, the adjustable bearing 1288 can be used to compensate for inaccuracies in the x-axis orientation of the carriage 1222 as it moves along the beam 1216. In the exemplary embodiment of FIG. 12 , each bearing 1286, 1287, 1288 includes an actuator, although one or more of the bearings may optionally be fixed or passively movable (e.g., using a spring-loaded mount). For example, in one exemplary embodiment, bearing 1286 is passively movable, thereby passively compensating for the actuation of adjustable bearings 1287 and 1288. As a further example, bearing 1288 may be fixed relative to carriage 1222, and as adjustable bearing 1287 is actuated, bearing 1286 may be passively or actively adjustable to compensate for the movement of bearing 1287. Similarly, bearing 1287 may be fixed, and one or both of bearings 1286, 1288 may include an actuator.

[0087] Referring now to FIG. 13, a technique for achieving rotation about the y-axis is shown. FIG. 13 is a view rotated 90 degrees about the z-axis from FIG. 12 and shows a cross-section along a plane through which the longitudinal axis of the beam extends. The y-axis is an axis perpendicular to the plane of the drawing of FIG. 13. In FIG. 13, two adjustment bearings 1390, 1392 are located on top of the carriage 1222. To rotate the carriage 1222 and print head 1224 counterclockwise about the y-axis, adjustment bearing 1390 is extended relative to the carriage 1222, and adjustment bearing 1392 is retracted relative to the carriage 1222. This causes the carriage 1222 to rotate relative to the beam 1216, as indicated by arrow R in FIG. 13. Clockwise rotation about the y-axis can be achieved by extending the adjusting bearing 1392 relative to the carriage 1222 and retracting the adjusting bearing 1390 relative to the carriage 1222, reversing the direction of rotation R. While in the exemplary embodiment shown in FIG. 13 both adjusting bearings 1390, 1392 are connected to actuators and described as such, in other exemplary embodiments only one of the adjusting bearings 1390, 1392 includes an actuator and a fixed bearing is used in place of the other adjusting bearing 1390, 1392. Rotation about the y-axis can be achieved in either direction by extending or retracting one adjusting bearing and maintaining the fixed bearing at a fixed distance from the carriage 1222. In this manner, inaccuracies in the y-axis direction that occur as the carriage 1222 moves along the beam 1216 can be compensated for.

[0088] Referring now to Figure 14, a view similar to Figure 13 is shown showing a cross-section of the beam 1216 and carriage 1222 taken along a plane extending through the longitudinal axis of the beam 1216. To adjust the z-position of the carriage 1222 and print head 1224 relative to the beam 1216, adjustment bearings 1390 and 1392 are extended or retracted simultaneously to move the carriage 1222 as needed relative to the beam 1216. This corrects for any z-position inaccuracies that may arise as the carriage 1222 moves along the beam 1216. While Figure 14 shows two adjustment bearings 1390, 1392, embodiments with a single adjustment bearing located in the center of the carriage 1222, or with three or more adjustment bearings, are also within the scope of the present disclosure.

[0089] 15, which is a view similar to FIG. 12 but showing a cross section of beam 1216 taken along a plane perpendicular to the longitudinal axis of beam 1216. To adjust the position of carriage 1222 in the y direction, adjustment bearings 1594 and 1596 are extended and adjustment bearing 1598 is contracted, causing carriage 1222 to move in the y direction. To reverse the movement of carriage 1222 in the y direction, adjustment bearings 1594 and 1596 are contracted and adjustment bearing 1598 is extended. In this manner, inaccuracies in the position of carriage 1222 and printhead 1224 in the y direction can be corrected.

[0090] Various exemplary embodiments of the present disclosure provide for changing the orientation of the carriage 1222 and print head 1224 about any one or combination of the x-axis, y-axis, and z-axis, and for translating the carriage 1222 and print head 1224 along any one or both directions perpendicular to the direction of movement of the carriage 1222 along the beam 1216 (i.e., the y-axis and z-axis as shown). Adjustments can be made dynamically based on real-time feedback, such as that described with respect to the workflow of Figure 8. Alternatively, adjustments can be made based on data collected and recorded during a calibration process, such as that described with respect to the workflow of Figures 9 and 10.

[0091] Devices manufactured using embodiments of the disclosed devices, systems, and methods include, but are not limited to, electronic displays or display components, printed circuit boards, or other electronic components that can be used, for example, in portable electronic devices, televisions, computer displays, or other electronic devices incorporating display technology.

[0092] It will be understood that the specific examples and embodiments described herein are non-limiting and that modifications in structure, dimensions, materials, and methods may be made without departing from the scope of the present teachings. Other embodiments according to the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention. The specification and examples are exemplary only and are intended to be encompassed under applicable law by the full scope of the following claims, including equivalents.

Claims

1. 1. A method for controlling a printing system having a printhead carriage supporting a printhead and mounted for translation along a beam, comprising: detecting rotational errors, positional errors, or both of the printhead; dynamically adjusting a position of a magnetic levitation bearing disposed to support the print head carriage on the beam based on the detected error; A method for dynamically adjusting the position of the magnetic levitation bearing to adjust the rotational orientation of the printhead, the position of the printhead, or both.

2. The method of claim 1 , wherein adjusting the position of the magnetic levitation bearing comprises actuating an actuator.

3. The method of claim 2 , wherein the actuator is a piezoelectric, pneumatic, hydraulic, or electromechanical actuator.

4. The method of claim 3 , wherein dynamically adjusting the position of the magnetic levitation bearing corrects the position error of the printhead, the rotation error of the printhead, or both.

5. The method of claim 1 , wherein a laser interferometer is used to sense the rotational error, the positional error, or both.

6. The method of claim 1 , further comprising sensing a position of the printhead carriage along the beam.

7. The method described in claim 1, wherein adjusting the position of one or more of the magnetic levitation bearings is performed while the print head moves along the beam and prints on the surface to be printed.

8. The method of claim 1 , wherein dynamically adjusting the position of the magnetic levitation bearing comprises actuating the magnetic levitation bearing along its longitudinal axis.

9. 1. A method for controlling a printing system having a printhead carriage supporting a printhead and mounted for translation along a beam extending in an x-axis direction in an x, y, z Cartesian coordinate system, comprising: Detecting information relating to a position of the print head along a path of movement extending in the x-axis direction; sensing information regarding one or more of a rotational orientation of the print head about the x-axis, the y-axis, and the z-axis, and a position of the print head along the y-axis and the z-axis; Based on the detected information, the printer to which the print head is attached dynamically adjusting one or both of the rotational orientation and the position of the printhead by actuating an actuator coupled to one or more magnetic levitation bearings of a printhead carriage; and storing information correlating positions of the one or more magnetic levitation bearings of the printhead carriage with corresponding positions along the path of travel of the printhead carriage.

10. 10. The method of claim 9, wherein storing information correlating the position of the one or more magnetic levitation bearings of the print head carriage comprises receiving information related to the position of the one or more magnetic levitation bearings of the print head carriage from an encoder.

11. 10. The method of claim 9, wherein sensing information related to one or more of the rotational orientation of the print head and the position of the print head comprises sensing information using a laser interferometer.

12. 10. The method of claim 9, wherein sensing information regarding one or more of the rotational orientation of the print head and the position of the print head comprises imaging a calibration mark of a calibration device with a camera.

13. The method of claim 11 , wherein the laser interferometer senses errors in the position, rotational orientation, or both of the print head.

14. 14. The method of claim 1, further comprising determining a position or orientation error of a mark on a substrate disposed in the printing system.

15. a substrate support system configured to support a substrate having a surface to be printed and to maintain the surface to be printed in an xy plane perpendicular to the z-axis of an x-axis, y-axis, z-axis Cartesian coordinate system; a beam extending in an x-axis direction across the substrate support system; a printhead carriage movably coupled to the beam for movement in the x-axis direction, the printhead carriage comprising one or more magnetic levitation bearings arranged to support the printhead carriage relative to the beam.

16. The printing system of claim 15 , wherein at least one of the one or more magnetic levitation bearings has a bearing surface facing the beam.

17. 16. The printing system of claim 15, wherein at least one of the one or more magnetic levitation bearings is adjustable along a longitudinal axis of the magnetic levitation bearing, the longitudinal axis being perpendicular to a bearing surface.

18. 17. The printing system of claim 16, further comprising at least one ball joint coupling one of the one or more magnetic levitation bearings to the printhead carriage.

19. 16. The printing system of claim 15, further comprising an actuator coupling one of the one or more magnetic levitation bearings to the printhead carriage.

20. The printing system of claim 19 , wherein the actuator comprises a piezoelectric element.

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