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1. (WO2007002660) SYSTEM AND METHODS FOR INKJET PRINTING FOR FLAT PANEL DISPLAYS
Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

SYSTEM AND METHODS FOR INKJET PRINTING
FOR FLAT PANEL DISPLAYS

BACKGROUND OF THE INVENTION
Field of the Invention
[0001] Embodiments of the present invention generally relate to electronic device manufacturing and more particularly to apparatus and methods for forming color filters in a flat panel display using inkjetting.

Description of the Related Art
[0002] Flat panel displays (FPDs) have become the display technology of choice for computer terminals, visual entertainment systems, and personal electronic devices such as cellular phones, personal digital assistants (PDAs), and the like. Liquid crystal displays (LCDs), and especially active matrix liquid crystal displays (AMLCDs), have emerged as the most versatile and robust of the commercially available FPDs. A basic element of the LCD technology is a color filter through which light is directed to produce a colored visual output. The color filter is made up of sub-pixels, which are typically red, green, and blue and are distributed in a pattern or array within an opaque (black) matrix which allows for improved resolution of the color filtered light.

[0003] Traditional methods of producing these color filters, such as dyeing, lithography, pigment dispersion, and electrodeposition, all have a major disadvantage of requiring the sequential introduction of the three colors. That is, a first set of sub-pixels having one color is produced by a series of steps, whereupon the process must be repeated twice more to apply all three colors. An area for improvement in the technology applicable to color filter production has been the introduction of improved dispensing devices, such as inkjets. By using an inkjet system, all three colors can be applied within the color filter matrix in one step and hence the process need not be carried out in triplicate.

[0004] One problem with effective employment of inkjet printing is that it is difficult to dispense ink accurately on a substrate, while maintaining a high throughput. Accordingly, there is a need for improved methods and apparatus to efficiently position inkjet heads above ink landing positions on a substrate to reduce the number of printing passes required for dispensing ink on the substrate.

SUMMARY OF THE INVENTION
[0005] The present invention generally provide a method for inkjet printing, comprising disposing a substrate on a substrate support, providing an inkjet printing module support having one or more inkjet heads disposed thereon, wherein the one or more inkjet heads are disposed above the substrate, and performing a printing operation by moving the one or more inkjet heads along a first axis and moving the substrate along a second axis perpendicular to the first axis such that the one or more inkjet heads dispense ink into one or more ink landing positions disposed in a pattern that is not aligned with either the first axis or the second axis.

[0006] Embodiments of the invention are directed to a method for inkjet printing, comprising disposing a substrate on a substrate support, providing an inkjet head that is disposed above the substrate support and has a plurality nozzle that are adapted to dispense an ink droplet therefrom, wherein the plurality of nozzles comprise a first nozzle and a second nozzle, dispensing ink from the first nozzle to a first region of a sub-pixel formed on a surface of the substrate, and dispensing ink from the second nozzle to the first region of the sub-pixel formed on the surface of the substrate.

[0007] Embodiments of the invention are directed to a method for inkjet printing, comprising disposing a substrate on a substrate support, providing a first inkjet head and a second inkjet head that are disposed above the substrate support, wherein the first and second inkjet heads each have a plurality of nozzles that are adapted to dispense an ink droplet therefrom, dispensing ink from a first nozzle formed in the first inkjet head on a first region of a sub-pixel formed on a surface of the substrate, and dispensing ink from a second nozzle formed in the second inkjet head on the first region of the sub-pixel formed on the surface of the substrate.

[0008] Embodiments of the invention are directed to a method for inkjet printing, comprising disposing a substrate on a substrate support, wherein the substrate has a plurality of sub-pixels formed on a surface of the substrate, providing an inkjet printing module having a first inkjet head and a second inkjet head that are disposed above the substrate, wherein the first and second inkjet heads each have a plurality of nozzles that are adapted to dispense an ink droplet therefrom, and dispensing a plurality of ink droplets on a first region of each of the sub-pixels, wherein dispensing the plurality of ink droplets comprises dispensing at least one ink droplet on the first region of a sub-pixel from a first nozzle formed in the first inkjet head, and dispensing at least one ink droplet on the first region of the sub-pixel from a second nozzle formed in the second inkjet head.

[0009] Embodiments of the invention are directed to a system for inkjet printing, comprising a substrate stage having a substrate supporting surface, a first inkjet head that contains a plurality of nozzles which are positioned over the substrate supporting surface, and a system controller that is configured to dispense an ink droplet from at least two of the plurality of nozzles onto a sub-pixel formed on a substrate disposed on the substrate supporting surface as the first inkjet head is transferred in a first direction.

[0010] Embodiments of the invention are directed to a system for inkjet printing, comprising a substrate stage having a substrate supporting surface, a first inkjet head that contains a first array of nozzles which are positioned over the substrate supporting surface, a second inkjet head that contains a second array of nozzles which are positioned over the substrate supporting surface, wherein the second array of nozzles are offset a fixed distance relative to the first array of nozzles during the inkjet printing process, and a system controller that is configured to dispense an ink droplet from one in the first array of nozzles and one nozzle in the second array of nozzles onto a sub-pixel formed on a substrate as the first inkjet head and the second inkjet head are transferred in a first direction.

BRIEF DESCRIPTION OF THE DRAWINGS
[0011] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0012] Figure 1 illustrates a perspective view of an inkjet printing apparatus in accordance with one or more embodiments of the invention.

[0013] Figure 2 illustrates a top view of the inkjet heads disposed above the substrate having display objects in connection with one or more embodiments of the invention.

[0014] Figure 3 illustrates a top view of each inkjet heads being oriented at a pitch angle a relative to the respective display object in connection with one or more embodiments of the invention.

[0015] Figure 4 is an illustrative top view of nine pixels disposed on a portion of one of the display objects.

[0016] Figure 5 illustrates a flowchart of a method for forming color filters on one or more display objects in accordance with one or more embodiments of the invention.

[0017] Figure 6 illustrates the movements of an inkjet head with respect to a substrate in connection with forming a mosaic color filter pattern in accordance with one or more embodiments of the invention.

[0018] Figure 7 illustrates the movements of another inkjet head with respect to the substrate in connection with forming the mosaic color filter pattern in accordance with one or more embodiments of the invention.

[0019] Figure 8 illustrates another example of a pattern that is not aligned with either the X-axis or the Y-axis in accordance with one or more embodiments of the invention.

[0020] Figure 9 illustrates the movements of another inkjet head with respect to the substrate in connection with forming the mosaic color filter pattern in accordance with one or more embodiments of the invention.

DETAILED DESCRIPTION
[0021] Figure 1 illustrates a perspective view of an inkjet printing apparatus 100 in accordance with one or more embodiments of the invention. The inkjet printing apparatus 100 may be configured to form color filters for flat panel displays. The inkjet printing apparatus 100 includes a stage positioning system 110 and an inkjet printing system 120. The stage positioning system 110 includes a substrate stage 130, which may be configured to move in the Y-axis direction. The substrate stage 130, however, may also be configured to move in the X-axis direction. The substrate stage 130 may be an X-Y table, such as those that are commonly used in semiconductor processing. A substrate 150 is configured to be disposed on the substrate stage 130. In one embodiment, at least one of the edges 151 of the substrate 150 are aligned along the X-axis or Y-axis directions. The substrate 150 may include one or more display objects 155 onto which ink may be dispensed during inkjet printing. The substrate 150 may be made of glass, polymers, and/or any other suitable material. Typically, the substrates 150 are rectangular in shape and may have a surface area greater than about 2000 cm2. Commonly, the processing equipment is generally configured to accommodate substrates having a surface area greater than about 15,000 cm2. Rectangular shaped substrates are not intended to be limiting as to the scope of the invention described herein, since aspects of the invention can be utilized to deposit a material on a surface of a substrate of any desired shape without varying from the basic scope of the invention.

[0022] The substrate stage 130 may bθ moved by a stage moving device (not shown), which may have one or more motors or actuation devices, such as a linear motor, for moving the substrate stage 130 in either the Y-axis or in the X-axis direction. The stage moving device may also be configured to rotate the substrate stage 130. This rotation feature may be used to align the substrate 150 and the display objects disposed thereon with an inkjet printing module 160 (described below) of the inkjet printing system 120. The rotation capabilities of the substrate stage 130 facilitate optimal alignment of the substrate 150 with the inkjet printing module 160, which may result in a more accurate and efficient inkjetting operation. To that end, the stage moving device may include a rotational motor configured to rotate the substrate stage 130 in either clockwise or counterclockwise direction. Other details of the substrate stage 130 and any components related thereto (e.g., a controller, a substrate securing device and the like) are provided in US Provisional Patent Application Serial No. 60/625,550, filed November 4, 2004 and entitled APPARATUS AND METHODS FOR FORMING COLOR FILTERS IN A FLAT PANEL DISPLAY BY USING INKJETTING, which is incorporated herein by reference in its entirety.

[0023] As briefly mentioned above, the inkjet printing system 120 includes the inkjet printing module 160, which may include three inkjet heads 122, 124 and 126. Each inkjet head 122, 124 and 126 may be used to dispense ink through one or more nozzles formed therein (e.g., nozzle 190 in Figures 2 and 3). As an example, each inkjet head 122, 124 and 126 may dispense a different color ink, depending upon the color system being utilized. For example, inkjet head 122 may dispense red ink, inkjet head 124 may dispense green ink and inkjet head 126 may dispense blue ink. Other ink colors, such as cyan, yellow, magenta or white, may also be dispensed by the inkjet heads 122, 124 and 126. Any one or more of the inkjet devices may dispense the same color ink or a clear ink. Although described as being equipped with three inkjets heads, the inkjet printing module 160 may have any number of inkjet heads, depending upon the application or use of the inkjet printing apparatus 100.

[0024] In addition to the inkjet printing module 160, the inkjet printing system 120 may further include an inkjet printing module support 125 on which the inkjet printing module 160 is mounted. The inkjet printing module 160 may be moveable along the inkjet printing module support 125 by an inkjet positioning device (not shown). The inkjet positioning device may include one or more motors or actuation devices for moving the inkjet printing module 160 along the inkjet printing module support 125 in the X-axis direction. The inkjet positioning device may also include one or more motors or actuation devices for moving the inkjet printing module 160 in the Y-axis direction.

[0025] Each of the inkjet heads 122, 124 and 126 may include other components related thereto, such as a height adjustment device, a head rotation actuator device, an ink reservoir and the like. Details of each component related to the inkjet heads 122, 124 and 126 are provided in US Provisional Patent Application Serial No. 60/625,550, filed November 4, 2004 and entitled APPARATUS AND METHODS FOR FORMING COLOR FILTERS IN A FLAT PANEL DISPLAY BY USING INKJETTING, which is incorporated herein by reference in its entirety. The head rotation actuator device may be configured to rotate the inkjet head. In this manner, the pitch or the angle at which an inkjet head is oriented relative to a display object disposed on the substrate can be changed depending upon the printing application. Each inkjet head may have numerous nozzles, such as between about 2 nozzles and about 760 nozzles. Preferably, each inkjet head has about 128 nozzles. In one aspect, an array nozzles may be formed in the inkjet heads 122, 124 and 126 to deliver the ink droplets in a desired pattern on the one or more display objects 155 disposed on the substrate. For example, referring to Figure 2, each of the inkjet heads 122, 124 and 126 have a linear array of nozzles 190 formed thereon (i.e., 19 shown on each inkjet head). The ink droplets may be dispensed at frequencies between about 0.01 kHz to about 100 kHz. The size of each droplet may be between about 2 μm to about 100 μm in diameter. The speed at which the droplets are dispensed may be between about 2 m/s to about 12 m/s. Examples of inkjet heads described herein include Spectra SE128A, SX128, or SM 128 inkjet head assemblies. The Spectra SE-128 inkjet head assembly has 128 nozzles, with each nozzle having a diameter of 38 μm and a space between adjacent nozzles of 508 μm. The Spectra SE-128 inkjet head assembly can dispense ink droplets having a volume of approximately 25 to 35 pico liters and can operate at a frequency of about 40 kHz.

[0026] Further, each of the inkjet heads 122, 124 and 126 may be independently moveable in one or more lateral directions relative to another of the inkjet heads 122, 124 and 126. Each of the inkjet heads 122, 124 and 126 may also be rotatable independently relative to the inkjet printing module support 125. Further, the inkjet heads 122, 124 and 126 may be independently moveable in one or more vertical directions (e.g., along a Z-axis) away from or toward the substrate 150. The lateral movement, rotation, and vertical movement may be performed independently, in any sequence, and/or substantially simultaneously. For example, each inkjet head may be (1) laterally moved and thereafter rotated; (2) each inkjet head may be rotated and thereafter laterally moved; and/or (3) each inkjet head may be simultaneously rotated and laterally moved. Similarly, vertical movement of an inkjet head may be performed before, after or during lateral movement and/or rotation of the inkjet head. In any case, the lateral motion, vertical motion and/or rotation of one inkjet head may occur while the remaining inkjet heads are held stationary.

[0027] As briefly mentioned above, the inkjet printing module support 125 may be moved in both an X-axis direction and a Y-axis direction. In this regard, once inkjet heads 122, 124 and 126 have been laterally moved and/or rotated to a given position and/or angular orientation, the inkjet printing module support 125 may affect the movement of the positioned and/or oriented inkjet heads 122, 124 and 126 over the respective display objects 155 to effectuate an ink printing operation on the display objects 155. Other details regarding the various manner in which the inkjet heads may be moved independently of each other are provided in US Patent Application Serial No. 11/019,967, filed December 22, 2004 and entitled APPARATUS AND METHODS FOR AN INKJET HEAD SUPPORT HAVING AN INKJET HEAD CAPABLE OF INDEPENDENT LATERAL MOVEMENT, which is incorporated herein by reference in its entirety.

[0028] The inkjet printing apparatus 100 may further include a system controller 102 and an image data file 104, which may be an integral component of the system controller 102 or an external device. The system controller 102 may be in communication with the inkjet printing module support 125 and the inkjet heads 122, 124 and 126 to control and monitor the operation and movement of the inkjet printing module support 125 and the inkjet heads 122, 124 and 126. The system controller 102 may also be in communication with the substrate stage 130 to control the movement of the substrate stage 130 in both the X-axis and the Y-axis directions.

[0029] The system controller 102 may be any suitable computer or computer system, including, but not limited to a mainframe computer, a minicomputer, a network computer, a personal computer, and/or any suitable processing device, component, or system. The system controller 102 may control the lateral movement of the inkjet heads 122, 124 and 126 in the X-axis and the Y-axis directions. The system controller 102 may also control the rotation of each of the inkjet heads 122, 124 and 126 relative to the inkjet printing module support 125.

[0030] The image data file 104 may contain data and/or information regarding the substrate 150 and/or display objects 155 to be processed by the inkjet printing apparatus 100. For example, the image data file 104 may include information that can be used by the system controller 102 to control the movement and printing operations of each of the inkjet heads 122, 124 and 126 and the substrate stage 130. As such, the system controller 102 may use the information contained in the image data file 104 in controlling the printing or inkjetting operations on the display objects 155.

[0031] Figure 2 illustrates a top view of the inkjet heads 122, 124 and 126 disposed above the substrate 250 having display objects 255 in connection with one or more embodiments of the invention. Each of the inkjet heads 122, 124 and 126 generally contain an array of nozzles 190 (i.e., 19 shown on each inkjet head) that are adapted to deliver the ink to at least a portion of the display objects 255 on the surface of the substrate 250. The inkjet heads 122, 124 and 126 are displayed as perpendicular to the display objects 255. However, one or more of the inkjet heads 122, 124 and 126 may be rotated to any appropriate angle relative to the display objects 255. Each of the inkjet heads 122, 124 and 126 may be rotated by the respective head rotation actuator device to "pitch" or orient the inkjet head and nozzles 190 at a desired angle relative to a respective display object. The angle at which the respective inkjet head is oriented relative to the display object may be referred to as the pitch or pitch angle.

[0032] Figure 3 illustrates a top view of each inkjet heads 122, 124 and 126 being oriented at a pitch angle a relative to the respective display object 255 in connection with one or more embodiments of the invention. The pitch angle a (see Figure 3) may vary from about 0 degrees to about 90 degrees. As illustrated in Figure 2, the pitch angle between the inkjet heads 122, 124 and 126 and the topmost edge of the display object 255 is about 0 degrees.

[0033] Figure 4 illustrates a top view of nine pixels 410, 420, 430, 440, 450, 460, 470, 480 and 490 disposed within a display object (e.g., display object 255 in Figures 2 and 3). Each pixel may have three sub-pixels (i.e., labeled either "A", "B", or "C" in Figure 4), that each may act as a color filter. In one embodiment, the colors red, green and blue may be used for making color filters for the respective pixels. For example, the color red may be assigned to the leftmost color filter region (labeled "A"), the color green may be assigned to the center color filter region (labeled "B") and the color blue may be assigned to the rightmost color filter region (labeled "C"). The color filter regions may be assigned in a different order or may be assigned different colors without varying from the scope of the invention described herein.

[0034] Each color filter region (e.g., "A", "B", or "C") may have one or more predetermined ink landing positions (e.g., 405) where a color ink drop may be deposited by the inkjet head 122. As an example, five ink landing positions are shown for the leftmost color filter region "A" in pixel 410. Although five ink landing positions are shown in each color filter region, any number of ink landing positions may be used in each color filter region. In operation, as the display object 255 is moved relative to the respective inkjet head 122, a drop of ink is deposited on each desired ink landing position. After the respective ink drops have been deposited on all of desired ink landing positions for a given processing period, the ink may be cured to complete the manufacture of the respective pixels of the display object. The ink may be cured by various methods and devices described in US Provisional Patent Application Serial No. 60/625,550, filed November 4, 2004 and entitled APPARATUS AND METHODS FOR FORMING COLOR FILTERS IN A FLAT PANEL DISPLAY BY USING INKJETTING, which is incorporated herein by reference in its entirety.

[0035] The manner in which inkjet heads dispense ink to the ink landing positions may be controlled by the system controller 102. The system controller 102 may operate pursuant to a computer program that utilizes information contained in the image data file 104 that is generated by an image data processor (not shown) and that corresponds to the substrate 150 being processed. The system controller 102 and the image data processor may be described in more detail in US Provisional Patent Application Serial No. 60/625,550, filed November 4, 2004 and entitled APPARATUS AND METHODS FOR FORMING COLOR FILTERS IN A FLAT PANEL DISPLAY BY USING INKJETTING, which is incorporated herein by reference in its entirety.

[0036] Referring back to Figure 1 , during the inkjet printing process, the substrate stage 130 and the inkjet printing module 160 may move with respect to each other in either the X-axis direction or the Y-axis direction. For example, the substrate stage 130 may be moved in the Y-axis direction underneath the inkjet printing module 160 while the inkjet printing module 160 remains stationary. In another example, the substrate stage 130 may be stationary while the inkjet printing module 160 is moved in the X-axis direction. As such, the inkjet printing process may involve instances in which the inkjet printing module 160 remains stationary while the substrate stage 130 is moved relative to the inkjet printing module 160 and instances in which the substrate stage 130 remains stationary while the inkjet printing module 160 is moved relative to the substrate stage 130, or any combination of the above in any desired order. Further, the inkjet printing module 160 and the substrate stage 130 may be moved simultaneously during all or a portion of the inkjet printing process. The rate at which the substrate stage 130 or the inkjet printing module 160 moves may vary from about 500 m/sec to about 1000 m/sec.

[0037] Referring to Figure 4, in one embodiment, the inkjet head 122 contains an array of two or more nozzles 190, such as the 17 nozzles shown in Figure 4. In this configuration, the array of nozzles may be adapted to dispense ink, contained in the inkjet head 122, in desired ink landing positions, such as the ink landing positions 405 in the color filter regions "A." As shown in Figure 4, the inkjet head 122 may contain a linear array of regularly spaced nozzles 190 that are oriented at a pitch angle a relative to an edge of the color filter regions. The pitch angle a will generally be set so that the spacing of the nozzles 190 in one direction (e.g., Y-direction in Figure 4) equals the distance between the ink landing position 405 in that same direction. In one aspect, the system controller 102 and the array of nozzles 190 are configured so that the ink droplets can be deposited at desired ink landing positions 405 within a desired color filter as the inkjet head 122 is translated relative to the color filters in the X-direction and/or the Y-direction. In one aspect, the system controller 102 is adapted to cause the inkjet head 122 to translate in the X-direction relative to the display objects while delivering an ink droplet on the desired ink landing positions 405 as each nozzle 190 passes over each desired ink landing position 405. For example, as shown in Figure 4, the left uppermost nozzle 190 in the inkjet head 122 is positioned over the topmost ink landing position 405 in the color filter regions "A" of pixel 410 so that an ink droplet can be dispensed at this location. In this way, the left uppermost nozzle 190 in the inkjet head 122 and the system controller 102 can be adapted to dispense ink droplets in the topmost ink landing positions 405 in the color filter regions "A" of pixels 440 and 470 as the inkjet head 122 is translated relative to the color filters in the X-direction (e.g., from left side to right side of Figure 4). In general, the system controller 102 can be used to control the translation of the landing positions relative to the inkjet head and the delivery of ink from each of the nozzles in an inkjet head so that a desired ink droplet pattern can be created on the surface of the substrate. The translation of the landing positions relative to the inkjet head may be accomplished by moving the inkjet head relative to the substrate and/or moving the substrate relative to the inkjet head.

[0038] Referring to Figures 1 and 4, in one embodiment, the substrate 250 is aligned so that the long side (e.g., side 403 in Figure 4) of a rectangular shaped sub-pixel (i.e., labeled either "A", "B", or "C" in Figure 4) is aligned along the predominant transfer direction of the substrate relative to the inkjet printing module 160. In general, the predominant transfer direction is the direction in which a large percentage of the movement of the substrate relative to the inkjet printing module 160 is made during the inkjet printing process. In yet another embodiment, the substrate 250 is aligned so that the short side (e.g., side 402 in Figure 4) of a rectangular shaped sub-pixel is aligned along the predominant transfer direction 401 (Figure 4) as the ink droplets are deposited on the surface of the substrate 250 during the inkjet printing process. One advantage of aligning the short side of a rectangular shaped sub-pixel along the predominant transfer direction is that the alignment of the columns of landing positions 405 (e.g., landing positions 405 in sub-pixels labeled "A" in pixels 410, 420 and 430) between the sub-pixels and the pixels can be more easily controlled, since each of the nozzles 190 in the inkjet head 122 are aligned so that they will pass over a desired landing positions in the desired regions of the substrate versus relying on the orientation of the finite number of nozzles 190 on the inkjet head 122 to define the accuracy of the spatial position of the ink droplets. The error created when the predominant transfer direction is aligned along the long side of the rectangular shaped sub-pixel can be seen by noting that the left uppermost nozzle 190 could be used to deposit ink drops in the landing positions 405 in sub-pixels labeled "A" in pixels 410, 420 and 430 as the inkjet head 122 is transferred in the "-Y"-direction, but none of the other nozzles 190 on the inkjet head 122 could be used to accurately deposit a column of ink drops in the desired landing positions 405 in the sub-pixels labeled "A" in pixels 440, 450 and 460, or the desired landing positions 405 in the sub-pixels labeled "A" in pixels 470, 480 and 490, during a single pass of the inkjet head 122. The variation the spacing between the columns of deposited ink droplets created when the predominant transfer direction is in-line with rows of landing positions is generally visible, and thus is seen as a defect in the formed color filter. Therefore, aspects of the invention described herein avoid this defect by allowing the system controller 102 to align the predominant transfer direction of the substrate relative to the inkjet printing module 160 so that it is not in-line with columns of landing positions and thus an ink droplet can be accurately placed on each of the desired landing positions as the nozzles pass over the desired landing positions during the inkjet printing process. One will note that the system controller 102 may need to align the inkjet printing inkjet head 122 and nozzles so that at least one nozzle 190 in the inkjet head 122 pass over each of the landing positions 405 (see Figure 4).

[0039] As mentioned above the image data file 104 may be used by the system controller 102 to control the printing or inkjetting operation on the display objects. For example, the image data file 104 may be used to control ink landing positioning on various ink landing positions. Accordingly, the image data file 104 may be generated using one or more substrate layout data, information regarding the number of ink drops to be deposited in each pixel's color filter region, the position and/or spacing of the ink drops for each color filter region, any desired or required offset distances of an ink landing position from a pixel's edge and information regarding the Y-axis resolution of the image and/or the display object. Details regarding the manner in which the image data file 104 is generated are provided in US Provisional Patent Application Serial No. 60/625,550, filed November 4, 2004 and entitled APPARATUS AND METHODS FOR FORMING COLOR FILTERS IN A FLAT PANEL DISPLAY BY USING INKJETTING, which is incorporated herein by reference in its entirety.

[0040] Substrate layout data may include data regarding the substrate, the type of substrate, the display objects on the substrate, information regarding the pixels on the substrate, the length of the substrate in the X-axis direction and in the Y-axis direction, the top margin of the substrate, the bottom margin of the substrate, the left side margin of the substrate, the right side margin of the substrate, the number and sizes of any gap or gaps between display objects, the number of display objects in the X-axis direction and the number of display objects in the Y-axis direction.

Substrate layout data may be used to determine the X and Y coordinate information for each pixel and the pixel color filter regions contained on the display objects.

[0041] The number and position of the ink landing positions along with the substrate layout data may be used to determine the position of each ink drop to be deposited in a respective pixel color filter region. In this manner, the image data processor may be programmed to automatically determine the respective ink landing positions to evenly distribute the ink drops inside a pixel's color filter region.

[0042] In some instances, the position of an ink drop may be shifted from its desired location due to errors in motion of the substrate stage 130. In extreme cases, a drop may land outside a pixel region and become a defect. To avoid such errors, dynamic adjustment of inkjet head position during inkjetting may be employed. For example, a visualization device, an inspection device or other similar devices, may be employed to check the inkjet heads and nozzle positions relative to a substrate pixel prior to an inkjet printing operation. InkJet head and/or nozzle position information may be fed to the system controller 102 and an offset may be determined to correct any positioning error.

[0043] In addition, inkjet head position and/or nozzle firing/jetting time may be adjusted on the fly, i.e., while the substrate stage 130 is in motion, based on the determined offset. For example, assuming that the substrate stage 130 travels along a Y-axis direction at a constant rate during inkjetting, an error in the Y-axis position of an inkjet head may be compensated for by jetting from a nozzle of the inkjet early, late or not at all. Likewise, an error in an X-axis direction position (e.g., perpendicular to the substrate stage 130's direction of travel) may be compensated for by adjusting the X-axis position of the inkjet head prior to printing (e.g., by moving the inkjet head to the left or right relative to the direction of travel so that a nozzle is properly positioned over a pixel location). Such an on-the-fly, self compensation mechanism may greatly improve printing accuracy by compensating for dynamic errors in inkjet head position. Further, the in-line position, lateral position, height, pitch, yaw, etc., of an inkjet head may be dynamically adjusted while the substrate stage 130 remains in motion.

[0044] Figure 5 is a flowchart of a method 500 for forming color filters on one or more display objects 155 in accordance with one or more embodiments of the invention. Once the substrate 150 containing the display objects 155 is placed on the substrate stage 130, the operation of the inkjet printing apparatus 100 may begin at step 510, at which the system controller 102 is activated. At step 520, the system controller 102 obtains and processes the image data file for the substrate 150.

[0045] At step 530, if the inkjet printing module support 125 is configured to remain stationary while the substrate stage 130 moves, the system controller 102 moves the substrate stage 130 to a home or start position for the substrate 150. Alternatively, if the substrate stage 130 is configured to remain stationary while the inkjet printing module support 125 moves, the system controller 102 moves the inkjet printing module support 125 to a home or start position. At step 540, the system controller 102 activates each of the inkjet heads 122, 124 and 126, e.g., by supplying ink to the inkjet heads or otherwise preparing the inkjet heads for printing.

[0046] At step 550, the system controller 102 commences the printing process by adjusting the lateral positions of each of the inkjet heads 122, 124 and 126. For instance, the inkjet heads 122, 124 and 126 may be adjusted for proper positioning during printing of ink into the pixels. During this step, the system controller 102 may also rotate one or more of the inkjet heads 122, 124 and 126 to the proper pitch angle relative to the display objects on the substrate 150.

[0047] At step 560, the system controller 102 commences the print passing operation of the inkjet printing module support 125 and each of the inkjet heads 122, 124 and 126. The print passing operation may include passing the substrate 150 below the inkjet printing module support 125 in the Y-axis direction from a starting edge to a stopping edge to print ink in all applicable display pixels on the display objects 155 on the substrate 150. In one embodiment, the system controller 102 moves the substrate stage 130 along the Y-axis direction and the inkjet printing module support 125 along the X-axis direction so that the inkjet heads 122, 124 and 126 may dispense ink along a pattern that is not aligned with either the X-axis or the Y-axis. For example, the pattern may be a diagonal pattern, as described in Figures 6 and 7. Figure 8 illustrates another example of a pattern that is not aligned with either the X-axis or the Y-axis.

[0048] Figure 6 illustrates the movements of an inkjet head 610 with respect to a substrate 620 in connection with forming a mosaic color filter pattern 600 in accordance with one or more embodiments of the invention. For the first ink drop, the inkjet head 610 remains stationary while the substrate 620 moves in the Y-axis direction toward the inkjet head 610 such that a first ink from nozzle 650 is dispensed into an ink landing position 630. For the second ink drop, the inkjet head 610 moves along the X-axis by a distance Δx toward an ink landing position 640 while the substrate 620 moves in the Y-axis direction by a distance Δy such that a second ink from nozzle 650 is dispensed into the ink landing position 640. Distance Δx represents the x component of the distance between ink landing position 630 and ink landing position 640. Distance Δy represents the y component of the distance between ink landing position 630 and ink landing position 640. Distance Δx, distance Δy, the respective speeds at which the inkjet head 610 and the substrate 620 move may be determined by the system controller 102 according to the image data file for the substrate 620. For the third ink drop, the inkjet head 610 moves along the X-axis by a distance 2Δx from ink landing position 630 toward an ink landing position 660 while the substrate 620 moves in the Y-axis direction by a distance 2Δy from ink landing position 630 such that a third ink from nozzle 650 is dispensed into the ink landing position 660.

[0049] The inkjet head 610 continues to move in the X-axis direction while the substrate 620 moves in the Y-axis direction until the inkjet head 610 dispenses ink to all the ink landing positions that are configured to be filled with the ink from the inkjet head 610. Figure 6 also illustrates the path or scan 670 for the inkjet head 610 during the first printing pass.

[0050] Figure 7 illustrates the movements of an inkjet head 710 with respect to the substrate 620 in connection with forming the mosaic color filter pattern 600 in accordance with one or more embodiments of the invention. The movements of the inkjet head 710 with respect to the substrate 620 are similar to the movements of the inkjet head 610, except that the substrate 620 moves in the opposite Y-axis direction during the second printing pass. Figure 7 also illustrates the path or scan 770 for the inkjet head 710 during the second printing pass.

[0051] In this manner, the rest of the ink landing positions within each color filter region may be filled during subsequent printing passes using different inkjet heads configured to dispense different colors. The inkjet heads may be configured to move in both forward and reverse directions along the X-axis during each printing pass. The substrate 620 may be configured to move continuously in the both forward and reverse directions along the Y-axis during each printing pass.

[0052] The foregoing description discloses only particular embodiments of the invention. Modifications of the above disclosed methods and apparatus which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For example, embodiments of the present invention may be applied to semiconductor processing and/or electronic device manufacturing. More particularly, resist patterns may be jetted onto substrates which may include glass, polymers, semiconductors, and/or any other suitable materials that are practicable. Thus, the jetted material may include ink, polymers, or any other suitable material that is practicable.

[0053] In one embodiment, as shown in Figure 9, a plurality of inkjet heads 910 are positioned and oriented so that at least one nozzle 911 in one or more of the inkjet heads 910 can deliver an ink droplets to each of the desired ink landing position(s) 930 contained within the desired color filters 920 of the mosaic color filter pattern 900. In this configuration, the nozzle 911 positions in adjacent inkjet heads 910 are staggered in the X and Y-directions so that all of the ink landing positions 930 within a region of the mosaic color filter pattern 900 can be covered as the plurality of inkjet heads 910 pass over the color filters 920. The number of inkjet heads 910, the staggered distance between nozzles, and the pitch angle a is dependent on the number and spacing between nozzles 911 in each inkjet head 910 and the spacing between the ink landing positions 930 (e.g., distance in the X-direction) in the color filters 920. In one aspect, it may be desirable to utilize enough inkjet heads 910 to assure that the color filter pattern (e.g., item # 900 in Figure 9) can have each of the desired color filters 920 formed after a single pass of the inkjet heads 910. Figure 9 illustrates one configuration of a plurality of inkjet heads 910 that can be aligned and translated to cover the desired landing positions 930 in the sub-pixels, or color filters 920, of a mosaic color filter pattern 900 in single pass as the heads are translated in the direction 970. The timing of when the ink droplets are dispensed from the nozzles 911 to cover the desired landing positions 930 is controlled by a system controller (not shown). In another aspect, it may be desirable to pass the inkjet heads 910 over the color filters 920 multiple times to provide the desired ink droplet coverage to fill all of the ink landing positions 930 within a region of the color filter pattern. In this case, it may be desirable to move the inkjet heads 910 relative to the color filter pattern (e.g., item # 900) in one or more directions (e.g., X and Y-directions) to provide the optimal coverage of the ink landing positions 930 in the shortest time.

[0054] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.