Liquid crystal cells – elements and systems – Nominal manufacturing methods or post manufacturing... – Aligning liquid crystal with means other than alignment layer
Reexamination Certificate
1999-07-23
2001-01-23
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Nominal manufacturing methods or post manufacturing...
Aligning liquid crystal with means other than alignment layer
C349S033000, C349S143000, C345S087000
Reexamination Certificate
active
06177976
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an LCD (Liquid Crystal Display) for displaying images including texts and graphics and, more particularly, to a method of producing and driving an LCD which is easy to produce and has a desirable viewing angle characteristic.
In a TN (Twisted Nematic) type LCD extensively used today, while a voltage is not applied, LC molecules are parallel to the surfaces of substrates and render “white”. On the application of a voltage, the molecules change their director in the direction of an electric field. As a result, sequential transition occurs from the “white” state to a “black” state. However, the viewing angle available with the conventional LCD is limited due to the behavior of the molecules occurring in response to the voltage. The limited viewing angle is particularly noticeable in the rising direction of LC molecules in the event of halftone display.
Implementations for improving the viewing angle are taught in, e.g., Japanese Patent Laid-Open Publication Nos. 63-106624 (Prior Art 1 hereinafter) and 6-43461 (Prior Art 2 hereinafter). The problem with Prior Art 1 is that it is not practicable without resorting to a photoresist step and a plurality of rubbing steps not necessary for the production of ordinary TN type LCDs. Prior Art 2 needs various kinds of microtreatment including a photoresist step for a common electrode and not necessary for the production of ordinary TN type LCDs. Further, the two substrates must be put together by a highly advanced technology. Moreover, when a voltage is applied to an electrode, it is likely that a sufficient electric field does not act in a certain portion, preventing the LC from sufficiently responding to the applied voltage. This lowers contrast available with the LCD.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method of producing and driving an LCD easy to produce, excellent in viewing angle characteristic, and high contrast.
In accordance with the present invention, an LCD has two substrates, an LC layer sandwiched between the two substrates and causing a plurality of regions of different kinds to coexist therein, a first electrode provided on at least one of the two electrodes and formed with an aperture, and a second electrode provided on the one electrode in alignment with the aperture.
Also, in accordance with the present invention, an LCD has two substrates, an LC layer sandwiched between the two substrates and causing a plurality of regions of different kinds to coexist therein, a first electrode provided on at least one of the two substrates, and a second electrode provided on, but insulated from, the first electrode.
Further, in accordance with the present invention, a method of producing an LCD includes the step of preparing an empty panel having two substrates, a first electrode provided on at least one of the two substrates and formed with an aperture, and a second electrode provided on the one substrate in alignment with the first electrode. After LC has been injected into the empty panel, the panel is cooled from a temperature higher than the isotropic phase-LC layer transition temperature of LC to a temperature lower than the transition temperature while a voltage higher than a voltage to be applied between the first electrode and a third electrode facing the first electrode is applied between the second electrode and the third electrode
Moreover, in accordance with the present invention, a method of producing an LCD includes the step of preparing an empty panel having two substrates, a first electrode provided on at least one of the two substrates, and a second electrode provided on, but insulated from, the first electrode. After LC has been injected into the empty panel, the panel is cooled from a temperature higher than the isotropic phase-LC layer transition temperature of LC to a temperature lower than the transition temperature while a voltage higher than a voltage to be applied between the first electrode and a third electrode facing the first electrode is applied between the second electrode and the third electrode.
REFERENCES:
patent: 5013137 (1991-05-01), Tsuboyama et al.
patent: 5309264 (1994-05-01), Lien et al.
patent: 5608556 (1997-03-01), Koma
patent: 5710611 (1998-01-01), Suzuki et al.
patent: 0 549 283 (1993-06-01), None
patent: 2 213 305 (1989-08-01), None
patent: 63-106624 (1988-05-01), None
patent: 6-43461 (1994-02-01), None
patent: 7-013164 (1995-01-01), None
patent: 7-273614 (1995-09-01), None
Y. Iimura et al., “Electro-optic characteristics of amorphous and super-multidomain TN-LCDs prepared by a non-rubbing method”, pp. 915-918, SID International Symposium Digest of Technical Papers, San Jose, Jun. 14-16, 1994.
N. Koma et al., “No-rub multi-domain TFT-LCD using surrounding-electrode method”, pp. 869-872, SID International Symposium Digest of Technical Papers, Orlando, May 23-25, 1995.
Murai Hideya
Suzuki Masayoshi
Suzuki Teruaki
Duong Tai V.
NEC Corporation
Sikes William L.
Young & Thompson
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