Liquid crystal cells – elements and systems – Nominal manufacturing methods or post manufacturing...
Reexamination Certificate
2000-04-27
2001-01-23
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Nominal manufacturing methods or post manufacturing...
C349S161000, C349S158000, C349S191000
Reexamination Certificate
active
06177975
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to precision alignment of plates and, more particularly, to a system and method for aligning and sealing plates relative to one another.
2. Description of the Related Art
In potentially very low cost manufacturing processes for displays, including liquid crystal displays (LCDs), it is desirable to provide precision alignment between plates. For example, in an LCD, a thin film transistor array glass plate and a color filter plate are aligned to a tolerance of within one micron. The alignment process is performed in air using robots and automatic optical alignment. However to achieve the required accuracy, manual intervention and adjustment is required.
The conventional alignment systems are complex and require maintenance and recalibration to ensure appropriate tolerances. Further, the conventional system cannot be implemented in a vaccuum environment which is preferable for display elements.
Therefore, a need exists for a system and method for aligning and sealing plates with high accuracy using lithography. A further need exists for aligning and sealing the plates in a vacuum environment.
SUMMARY OF THE INVENTION
A system for aligning two plates, in accordance with the present invention, includes a first plate having a lithographically patterned structure formed on a first surface. A second plate also has a lithographically patterned structure formed on a second surface, the first and second surfaces being disposed to face each other. The patterned structures of the first and second plates have corresponding and opposing edges to provide an interference fit between the patterned structures of the first and second plates wherein self-alignment between the first and second plates is realized by engaging the corresponding and opposing edges in the interference fit.
In alternate embodiments, the corresponding and opposing edges may include interlocking angled edges. The patterned structures may be continuous about the first and second plates and may form a seal between the first and second plates. The patterned structures may include a metal material. The patterned structures may form a continuous lip about the first and second plates and the corresponding and opposing edges may include corresponding and opposing undercuts in the lips of the first and second plates. The patterned structures preferably include a resist material. The first plate and the second plate may be employed in a liquid crystal display. The first plate and the second plate are preferably aligned to a tolerance of less than one micron.
A method for aligning two plates, in accordance with the present invention includes the steps of providing a first plate having a lithographically patterned structure formed on a first surface and a second plate having a lithographically patterned structure formed on a second surface, the first and second surfaces being disposed to face each other, the patterned structures of the first and second plates having corresponding and opposing edges to provide an interference fit between the patterned structures of the first and second plates, coarsely aligning the first plate with the second plate in a first state wherein the first state includes an interference between the patterned structures, adjusting at least one of the first plate and the second plate to provide a second state having a clearance fit between the patterned structures of the first and second plates and moving the first and second plates together and returning to the first state to align the first and second plates relative to each other.
Another method for aligning two plates includes the steps of providing a first plate having a lithographically patterned structure formed on a first surface and a second plate having a lithographically patterned structure formed on a second surface, the first and second surfaces being disposed to face each other, the patterned structures of the first and second plates having corresponding and opposing edges to provide an interference fit between the patterned structures of the first and second plates, placing the first and second plates in a vacuum environment during alignment, coarsely aligning the first plate with the second plate in a first state wherein the first state includes an interference between the patterned structures, heating the first plate, the first plate having the patterned structure disposed externally relative to the patterned structure of the second plate, the heating providing a second state having a clearance fit between the patterned structures of the first and second plates and moving the first and second plates together and returning to the first state to align the first and second plates relative to each other.
Alternate methods may include the step of coarsely aligning which is performed using an optical alignment process. The patterned structure of the first plate may be exteriorly disposed to the patterned structure of the second plate and the step of adjusting may further include the step of expanding the first plate by heating. The patterned structure of the first plate may be exteriorly disposed to the patterned structure of the second plate and the step of adjusting may further include the step of contracting the second plate by cooling. The steps of both expanding the first plate by heating and contracting the second plate by cooling may be included.
In still other methods, the patterned structures of the first and second plates may each include a continuous lip including undercuts and the method may further include the step of engaging the lips between the first and second plates to form a seal. The method may further include the step of forming a seal between the first and second plates using a sealant. The step of providing a vacuum environment for aligning the first and second plates may also be included. The method may further include the step of forming the patterned structures by employing a resist material.
These and other objects, features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
REFERENCES:
patent: 4043647 (1977-08-01), Oue et al.
patent: 5831710 (1998-11-01), Colgan et al.
patent: 6104466 (2000-08-01), Buchwalter et al.
Shaw et al., “Negative Photoresists for Optical Lithography,” IBM J. Res. Develop., vol. 41, No. 1/2, pp. 81-94, Jan./Mar. 1997.
Hatzakis et al., “Single-Step Optical Lift-Off Process,” IBM J. Res. Develop., vol. 24, No. 4, pp. 452-460, Jul. 1980.
Buchwalter Stephen L.
Lewis David A.
Lien Shui-Chih Alan
Purushothaman Sampath
Ritsko John J.
Bitetto James J.
F. Chau & Associates LLP
International Business Machines - Corporation
Parker Kenneth
Qi Mike
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