WO2005029178A2

WO2005029178A2 - A system and method for the direct imaging of color filters

Info

Publication number: WO2005029178A2
Application number: PCT/IL2004/000882
Authority: WO
Inventors: Abraham Gross; Raanan Adin; Yigal Katzir; David Fisch
Original assignee: Orbotech Ltd.
Priority date: 2003-09-22
Filing date: 2004-09-22
Publication date: 2005-03-31
Also published as: TWI249083B; WO2005029178A8; JP2007506136A; KR20060097711A; WO2005029178A3

Abstract

A system and method for the laser direct imaging of stripe patterns onto a photosensitized surface comprising scanning a laser beam over a photo sensitized, surface. Stripe patterns are exposed by employing a pulse laser and synchronizing the delivery of pulses to expose additive regions of stripes. Alternatively, a laser is scanned over a rotated panel, and the speed of translation, speed of scanning and degree of rotation are coordinated to expose each stripe continuously, and avoid exposing regions between stripes.

Description

A SYSTEM AND METHOD FOR THE DIRECT IMAGING OF COLOR FILTERS

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60/503,887, filed September 22, 2003, the disclosure of which is incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to systems and methods for the direct imaging patterns on photosensitive surfaces, and more specifically to the direct imaging of color filter patterns on flat panel display substrates.

BACKGROUND OF THE INVENTION [0003] Flat panel displays, such as TFT (thin film transistor) displays, typically employ color filters to display color images. The color filters typically include each one of three primary colors, typically red, green and blue. The color filters are arranged in a fixed pattern, typically a striped pattern. Each color filter overlays some, but not all pixels on a panel. A color image is formed on a display by passing light through selected pixels according to location and color attributed by the color filter.

[0004] Conventionally, photolithographic processes are used to form the color filters on flat panel displays. A suitably dyed photosensitive filter material is selectively exposed in the desired filter pattern, typically a striped pattern, and developed. Typically, the unexposed portions of the filter material are removed, thereby leaving color filters only at desired locations. Masks are employed to determined which portions of the photosensitive filter material are to be exposed.

SUMMARY OF INVENTION

[0005] The present invention seeks to provide improved systems and methodologies for forming color filters on flat panel displays. [0006] The present invention further seeks to utilize laser direct imaging systems and methodologies, particularly digital systems and methodologies, to selectably expose a photosensitive material to form strip patterns. Strip patterns include, but are not limited to, color filters on flat panel displays.

[0007] In accordance with a general aspect of the invention, a laser direct imaging system is suitably arranged to optimize energy utilization of the laser to expose striped portions of the photosensitive material. Optimization is accomplished when using a pulsed laser by timing the delivery of pulses to locations of strips to be exposed. Another methodology for optimizing laser power is to orient a panel to be scanned relative to the scanner to take into account transportation during scanning such that each strip may be scanned continuously without modulating the laser on and off. Orientation of the stripes, the speed of scanning and the speed of mutual relative transportation between a panel to be exposed and the scanner are coordinated so that upon completion of scanning a first stripe, the laser beam is returned to scan a next strip to be exposed. Intermediate portions which are not to be exposed are automatically skipped. [0008] In accordance with another general aspect of the invention, a laser direct imaging system includes scanner scanning a beam in a scan direction, and a deflector deflecting the scanned beam in the cross scan direction. Deflection in the cross scan direction is coordinated with transportation of a panel which is to be exposed to compensate for transportation in the cross scan direction. Suitable deflectors include acousto-optical deflectors, in which a laser beam is deflected as a function of the frequency of an acoustic wave in the modulator.

[0009] There is thus provided in accordance with an embodiment of the invention a system and method for imaging a pattern onto a photosensitized surface, including a laser beam source outputting a laser beam; a support surface supporting a panel, the panel comprising an array of pattern elements formed thereon, the panel further including a photosensitive material overlaying the pattern; a scanner scanning the laser beam in multiple passes along a scan path across the photosensitized surface to expose portions of the photosensitive material; and a rotator providing a mutual angular orientation between the panel and the scanner so that a row of pattern elements on the panel intersects the scan path when the panel and the scanner are in a fixed position relative to each other. [0010] Various embodiments include one or more of the following additional and alternative features:

[0011] A transporter is operative to provide mutual relative translation between the scanner and the panel in a cross scan direction, the cross scan direction intersecting the scan path.

[0012] The cross scan direction is transverse to the scan path. [0013] The panel rotator aligns the panel so that a row of pattern elements is parallel to the effective scan path during mutual relative translation.

[0014] The panel rotator rotates the panel such that during each pass of the laser beam, the laser beam exposes a portion of the photosensitized surface overlaying the pattern elements of a single a row of pattern elements.

[0015] A speed of mutual relative translation is coordinated with a speed of scanning such that in each pass of the laser beam a portion of the photosensitized surface overlaying the pattern elements of a subsequent row of pattern elements is exposed.

[0016] The laser beam source outputs a pulsed laser beam defined by a multiplicity of temporally separated laser pulses, and each pulse exposes an overlapping portion of the photosensitized surface. Alternatively, the laser beam is a continuous wave laser beam.

[0017] The rotator rotated the panel relative to the scanner. Alternatively, the scanner is rotated relative to a support structure supporting the panel.

[0018] In accordance with another embodiment of the present invention, there is thus provided a system for imaging a pattern onto a photosensitized surface, including a laser beam source outputting a laser beam defined by a sequence of temporally separated laser pulses; and a scanner scanning the laser beam across a photosensitized surface in a scan direction; wherein the scanning and the sequence of laser pulses are synchronized to deliver each laser pulse to a noncontiguous location in the scan direction of a pattern to be imaged.

[0019] Various embodiments include one or more of the following additional and alternative features:

[0020] The laser beam source is a Q-switch pulsed laser. [0021] The scanner is a rotating polygon.

[0022] A transporter provides mutual relative translation between the scanner and the photosensitized surface.

[0023] A system controller controls at least one of: a pulse rate of pulses defining the laser beam, a speed of the mutual relative translation, and a speed of scanning.

[0024] The scanner is operative to deliver pulses in first scan to a first row to be exposed, and to deliver pulses in a second scan to a second row to be exposed that is contiguous with the first row to be exposed.

[0025] The scanner delivers each pulse to expose an additive region to form a stripe.

[0026] The pattern to be imaged comprises a pattern of color filter stripes on a flat panel display. [0027] In accordance with still another embodiment of the present invention, there is thus provided a system and method for imaging a pattern onto a photosensitized surface, including a laser beam source outputting a laser beam; a scanner scanning the laser beam across a photosensitized surface in a scan direction; a transporter providing mutual relative translation between the scanner and the photosensitized surface in a cross scan direction that is transverse to the scan direction; and a laser beam deflector deflecting the laser beam in the cross scan direction synchronously with the mutual relative translation as the laser beam is scanned in the scan direction. BRIEF DESCRIPTION OF DRAWINGS

[0028] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: [0029] Fig. 1 is a part simplified pictorial, part block diagram of a system for exposing strip patterns in photosensitive materials in accordance with an embodiment of the present invention.

[0030] Fig. 2 is a part simplified pictorial, part block diagram of a system for exposing strip patterns in photosensitive materials in accordance with another embodiment of the present invention.

[0031] Fig. 3 is a part simplified pictorial, part block diagram of a system for exposing strip patterns in photosensitive materials in accordance with still another embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0032] Reference is made to Figure 1, which is a part simplified pictorial, part block diagram of a system 10 for exposing strip patterns in photosensitive materials in accordance with an embodiment of the present invention. The systems and methodologies described herein are particularly suitable for fabricating color filter strips that are part of flat panel displays, although the exposure of strip patterns in suitable photosensitive materials is also contemplated. [0033] Briefly, flat panel displays include an array of pixels. A color filter is associated with each of the pixels. An image is displayed on the panel by selectively outputting light from the pixels, each pixel being selected according to its location and color. [0034] Typically, color filters are disposed in strips and each color filter strip overlays a row (or column) of pixels on a display panel 12. The filters are fabricated by suitably exposing a dyed photosensitive material.

[0035] In accordance with an embodiment of the invention, laser direct imaging technologies are employed to expose the photosensitive material. The invention may be carried out for example by suitably adapting scanning laser direct imaging equipment, such as the DP™ series of laser direct imaging systems, commercially available from Orbotech Ltd. of Yavne, Israel.

[0036] As seen in Fig. 1, in accordance with an embodiment of the invention, system 10 includes a pulsed laser 20 outputting a pulsed laser beam 22. Pulsed laser beam 22 is defined by a sequence of temporally separated laser pulses 24, rather than a continuous beam. Suitable lasers for providing a pulsed laser beam include, for example, Q-switch diode pumped solid state lasers commercially available from any of several laser suppliers including Coherent, Inc. and Spectra Inc. of California U.S.A.

[0037] The laser pulses 24 are passed through suitable pre- scan optics 26 and directed to impinge on a scanner 28, such as a rotating polygon having a plurality of facets 30. Pre- scan optics 26 typically include a plurality of lenses (not shown) which are selected to suitably shape laser beam 22 so that each laser pulse 24 exposes a spot having a desired size and shape on panel 12. It is noted that scanner delivers each laser pulse to a different location on panel 12. The respective paths of laser pulses 24 are denoted by the broken lines .

[0038] As the polygon of scanner 28 rotates in the direction of arrow 32 (the scan direction) , beam 22 impinges on one of the facets 30 of the polygon, which passes the beam through scanning optics 34. Typically, scanning optics 34 include an f-θ scan lens and other optical elements (not shown) . As the polygon rotates, beam 22 is scanned along a scan path in a scan direction indicated by arrow 36. [0039] Pattern data 40 corresponding to a pattern to be exposed is supplied to a system controller 42,-. System controller 42 controls one or more of: the rotational speed of the polygon of scanner 28, the mutual translation of panel 12 relative to scanner 28 and a clock governing the generation laser pulses 24. Although Fig. 1 depicts a translator moving panel 12 in the direction of arrow 46 (the cross scan direction) while scanner 28 remains stationary, actual system design may be such that panel 12 is kept stationary while scanner 28 is moved. [0040] In Fig. 1, timing signals 48 output by a pulse generator 50 are shown. These timing signals correspond to laser pulses 24 of laser beam 22. In accordance with an embodiment of the invention, laser pulses 24 are synchronized with the rotation of the polygon in scanner 28 so that each laser pulse 24 exposes an additional portion of a photosensitive material on panel 12 thereby to form exposed regions 60. Because of the temporal separation between laser pulses 24 in combination with continuous rotation of scanner 28, each of the exposed regions 60 is mutually non-contiguous with other exposed regions 60. The inherent on-off modulation of a pulsed beam, namely the time between pulses when the beam is "off" is utilized to move the beam 22 from one exposed region 60 to the next exposed region.

[0041] Upon the completion of a scan path, that is to say once laser beam 22 reaches the end of a swath to be scanned, which may, but does not have to be the entire width of panel 12, the next facet of the polygon in scanner 28 is rotated into place to instantaneously return laser beam 22 to the beginning of the scan path. Laser beam 22 is once again scanned along the scan path. Because of mutual relative translation between panel 12 and scanner 28, provided for example by a panel transporter 44, new locations on panel 12, adjacent to previously scanned locations, are now scanned. It is thus noted that each scan path is contiguous with a previous scan path, thereby generating an additive portion to each exposed region 60 to extend the exposed region as a strip in the cross scan direction. [0042] Reference is now made to Fig. 2 which is a part simplified pictorial, part block diagram of a system 110 for exposing strip patterns in photosensitive materials in accordance with another embodiment of the present invention. The photosensitive materials include a dyed filter material suitable for fabricating color filters on a panel 112, such as flat panel display. The dyed filter material typically is laid over a pixel pattern 113 already formed on panel 112. Although both system 110 and system 10 are configured to make optimal use of a laser direct imager for exposing patterns of non-contiguous strips, system 110 exposes each strip continuously, while system 10 exposes an additive region on each strip.

[0043] As seen in Fig. 2, system 110 includes a laser 120 outputting a laser beam 122 may be a continuous wave laser beam or a pulsed laser beam, provided, for example by a Q- switch diode pumped solid state laser, as is commercially available from any of several laser suppliers including Coherent, Inc. and Spectra Inc. of California U.S.A. In accordance with an embodiment of the invention, when a pulsed laser is used, as noted below system design (spot size, scanning speed, and the speed of mutual translation) needs to be such that a spot exposed by each of the pulses mutually overlaps at least one other spot in order to ensure the exposure of a continuous strip.

[0044] Laser beam 122 is passed through suitable pre-scan optics 126 and directed to impinge on a scanner 128, such as a rotating polygon having a plurality of facets 130. Pre-scan optics 126 typically include a plurality of lenses (not shown) which are selected to suitably shape laser beam 122 for exposing a continuous strip on panel 112.

[0045] As the polygon of scanner 128 rotates in the direction of arrow 32 (the scan direction) , beam 122 impinges on one of the facets 130 of the polygon, which passes the beam through scanning optics 134. Typically, scanning optics 134 include an f-θ scan lens and other optical elements (not shown) . As the polygon rotates, beam 122 is scanned along a scan path in a nominal scan direction indicated by arrow 136.

[0046] During scanning, panel 112 and scanner 128 are mutually relatively translated, for example by a transporter

144, in a cross scan direction indicated by arrow 146. It is noted that because of the mutual relative translation during scanning, the actual direction of scanning is slightly skewed, as indicated by arrow 148.

[0047] It is a feature of the present embodiment that a rotator 150 establishes a mutual angular offset between panel 112 and scanner 128 during scanning. Thus, absent mutual relative translation of panel 112 and scanner 128, rows of pattern elements in pattern 113, intersect an axis corresponding to the nominal scan direction 136. Upon introduction of mutual relative translation between panel 112 and scanner 128, the actual scan direction matches the orientation of rows of pattern elements 113 thereby facilitating the continuous exposure of regions 160.

[0048] In Fig. 2, it is seen that pattern data 140 corresponding to a pattern to be exposed is supplied to a system controller 142. System controller 142 controls one or more of: the rotational speed of the polygon of scanner 128, the mutual translation of panel 112 relative to scanner 128 and rotational orientation of panel 112 relative to scanner 128. [0049] Although Fig. 2 depicts a translator 144 moving panel 112 in the direction of arrow 146 (the cross scan direction) while scanner 128 remains stationary, actual system design may be such that panel 112 is kept stationary while scanner 128 is moved. The translator may operate to directly move panel 112, for example while panel 112 is supported on an air cushion, or it may operate to move a support table supporting panel 112.

[0050] Moreover, although Fig. 2 schematically shows a rotator 150 operative to rotate panel 112. It is noted that in accordance with an embodiment of the invention rotator 150 may operate directly on panel 112, or on a support table (not show) supporting panel 112, or it may rotate the scanner 128 relative to panel 112, while panel 112 is held stationary. The rotator may be operative once panel is already placed on system 128, or it may rotate panel 112 prior to placing it on system 110, for example as part of a pick and place type loader. [0051] System 110 is configured so that upon the completion of a scan path, that is to say once laser beam 122 reaches the end of a swath to be scanned, the next facet of the polygon in scanner 128 is rotated into place to instantaneously return laser beam 122 to the beginning of the scan path. System control 142 determines the appropriate relative angular orientation of panel 112 and scanner 128, along with the speed of translation and the speed of scanning so that each scan path corresponds to a stripe region 160 to be exposed, and to skip the region between stripes. [0052] Reference is now made to Fig. 3 which is a part simplified pictorial, part block diagram of system 210 for exposing strip patterns in photosensitive materials in accordance with another embodiment of the present invention. The photosensitive materials include a dyed filter material suitable for fabricating color filters on a panel 112, such as flat panel display. The dyed filter material is laid over a pixel pattern 113 already formed on panel 112.

[0053] In the embodiment seen in Fig. 3, system 210 is identical to system 110 in all respects except that it includes and additional, optional, cross scan deflector 370 in communication with system control 142 operative to deflect beam 122 in the cross scan direction. Thus in accordance with an embodiment of the invention, system control 142 further controls an angle of deflection of beam 122 to compensate for mutual relative translation between panel 112 and scanner 128. The compensation provided by deflector 370 may be in addition to, or in place of, establishing a mutual relative rotation between panel 112 and scanner 128 as described hereinabove with respect to Fig. 2.

[0054] Deflector 370 optionally is an acousto optical deflector employing an acoustic wave to deflect laser beam 122. The amount of deflection is controlled by changing the frequency of the acoustic wave in deflector 370, as known in the art.

[0055] It is appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the present invention includes modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.

Claims

1. A system for imaging a pattern onto a photosensitized surface, comprising: a laser beam source outputting a laser beam; a support surface supporting a panel, said panel comprising an array of pattern elements formed thereon, said panel further including a photosensitive material overlaying said pattern; a scanner scanning said laser beam in multiple passes along a scan path across said photosensitized surface to expose portions of said photosensitive material; and a rotator rotating providing a mutual angular orientation between said panel and said scanner so that a row of pattern elements on said panel intersects said scan path when said panel and said scanner are in a fixed position relative to each other.

2. The system claimed in claim 1, further comprising a transporter operative to provide mutual relative translation between said scanner and said panel in a cross scan direction, said cross scan direction intersecting said scan path.

3. The system claimed in claim 2, wherein said cross scan direction is transverse to said scan path.

4. The system claimed in claim 2, wherein said panel rotator is operative to align said panel so that a row of pattern elements is parallel to said scan path during said mutual relative translation.

5. The system claimed in claim 1, wherein said panel rotator rotates said panel such that during each pass of said laser beam, said laser beam exposes a portion of said photosensitized surface overlaying the pattern elements of a single a row of pattern elements.

6. The system claimed in claim 5, further comprising a transporter operative to provide mutual relative translation between said scanner and said panel.

7. The system claimed in claim 6, wherein a speed of said mutual relative translation is coordinated with a speed of scanning such that in each pass of said laser beam a portion of said photosensitized surface overlaying the pattern elements of a subsequent row of pattern elements is exposed.

8. The system claimed in claim 7, wherein said subsequent row of pattern elements is separated from a previous row of patter elements by at least one intermediate row of pattern elements.

9. The system claimed in claim 1, wherein said laser beam source outputs a pulsed laser beam defined by a multiplicity of temporally separated laser pulses.

10. The system claimed in claim 9, wherein each pulse exposes a portion of said photosensitized surface.

11. The system claimed in claim 10, wherein at least two portions of said photosensitized surface mutually overlap.

12. The system claimed in claim 1, wherein said laser beam source outputs a continuous wave laser beam.

13. The system claimed in claim 1, wherein said rotator is operative to rotate said panel relative to said scanner.

14. The system claimed in claim 1, wherein said rotator is operative to rotate said scanner relative to a support structure supporting said panel.

15. A method for imaging a pattern onto a photosensitized surface, comprising: outputting a laser beam; supporting a panel, said panel comprising an array of pattern elements formed thereon, said panel further including a photosensitive material overlaying said pattern; scanning said laser beam in multiple passes along a scan path across said photosensitized surface to expose portions of said photosensitive material; and providing a mutual angular orientation between said panel and said scanner so that a row of pattern elements on said panel intersects said scan path when said panel and said scanner are in a fixed position relative to each other.

16. The method claimed in claim 15, further comprising providing mutual relative translation between said scanner and said panel in a cross scan direction, said cross scan direction intersecting said scan path.

17. The method claimed in claim 16, wherein said cross scan direction is transverse to said scan path.

18. The method claimed in claim 16, wherein said providing mutual angular orientation comprises aligning said panel so that a row of pattern elements is parallel to an actual scan path during said mutual relative translation.

19. The method claimed in claim 15, wherein providing mutual angular orientation comprises aligning said panel such that during each pass of said laser beam, said laser beam exposes a portion of said photosensitized surface overlaying the pattern elements of a single a row of pattern elements.

20. The method claimed in claim 19, further comprising providing mutual relative translation between said scanner and said panel.

21. The method claimed in claim 20, further comprising coordinating a speed of said mutual relative translation and a speed of scanning such that in each pass of said laser beam a portion of said photosensitized surface overlaying the pattern elements of a subsequent row of pattern elements is exposed.

22. The method claimed in claim 21, wherein said subsequent row of pattern elements is separated from a previous row of patter elements by at least one intermediate row of pattern elements .

23. The method claimed in claim 15, wherein outputting a pulsed laser beam comprises outputting a pulsed laser beam.

24. The method claimed in claim 23, wherein each pulse exposes a portion of said photosensitized surface.

25. The method claimed in claim 24, wherein at least two portions of said photosensitized surface mutually overlap.

26. The method claimed in claim 15, wherein outputting a laser beam comprises outputting a continuous wave laser beam.

27. The method claimed in claim 15, wherein said rotator is operative to rotate said panel relative to said scanner.

28. The method claimed in claim 15, wherein said rotator is operative to rotate said scanner relative to a support structure supporting said panel.

29. A system for imaging a pattern onto a photosensitized surface, comprising, a laser beam source outputting a laser beam defined by a sequence of temporally separated laser pulses; and a scanner scanning said laser beam across a photosensitized surface in a scan direction; wherein said scanning and said sequence of laser pulses are synchronized to deliver each laser pulse to a noncontiguous location in said scan direction of a pattern to be imaged.

30. The system claimed in claim 29, where said laser beam source comprises a Q-switch pulsed laser.

31. The system claimed in claim 29, wherein said scanner comprises a rotating polygon.

32. The system claimed in claim 29, further comprising a transporter providing mutual relative translation between said scanner and said photosensitized surface.

33. The system claimed in claim 32, further comprising a system controller controlling at least one of: a pulse rate of pulses defining said laser beam, a speed of said mutual relative translation, and a speed of scanning.

34. The system claimed in claim 32, wherein said scanner is operative to deliver pulses in first scan to a first row to be exposed, and to deliver pulses in a second scan to a second row to be exposed that is contiguous with said first row to be exposed.

35. The system claimed in claim 34, wherein said scanner delivers each pulse to expose an additive region to form a stripe.

36. The system claimed in claim 29, wherein the pattern to be imaged comprises a pattern of color filter stripes on a flat panel display.

37. A method for imaging a pattern onto a photosensitized surface, comprising: outputting a laser beam defined by a sequence of temporally separated laser pulses; scanning said laser beam across a photosensitized surface in a scan direction; and synchronizing said scanning and said sequence of laser pulses to deliver each laser pulse to a non-contiguous location in said scan direction of a pattern to be imaged.

38. The system claimed in claim 37, where said outputting a laser beam comprises a outputting a laser beam from a Q-switch pulsed laser.

39. The method claimed in claim 37, wherein said scanning comprises reflecting said laser off of a rotating polygon.

40. The method claimed in claim 37, further comprising a providing mutual relative translation between a scanner and said photosensitized surface.

41. The method claimed in claim 40, further comprising controlling at least one of: a pulse rate of pulses defining said laser beam, a speed of said mutual relative translation, and a speed of scanning.

42. The method claimed in claim 40, wherein said scanning comprises delivering pulses in first scan to a first row to be exposed, and delivering pulses in a second scan to a second row to be exposed that is contiguous with said first row to be exposed.

43. The method claimed in claim 42, wherein said scanning comprises delivering each pulse to expose an additive region to form a stripe.

44. The method claimed in claim 37, wherein the pattern to be imaged comprises a pattern of color filter stripes on a flat panel display.

45. A system for imaging a pattern onto a photosensitized surface, comprising: a laser beam source outputting a laser beam; a scanner scanning said laser beam across a photosensitized surface in a scan direction; a transporter providing mutual relative translation between said scanner and said photosensitized surface in a cross scan direction that is transverse to said scan direction; and a laser beam deflector deflecting said laser beam in said cross scan direction synchronously with said mutual relative translation as said laser beam is scanned in said scan direction.

46. A method for imaging a pattern onto a photosensitized surface, comprising: outputting a laser beam; scanning said laser beam across a photosensitized surface in a scan direction; providing mutual relative translation between said scanner and said photosensitized surface in a cross scan direction that is transverse to said scan direction; and deflecting said laser beam in said cross scan direction synchronously with said mutual relative translation as said laser beam is scanned in said scan direction.