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US4856875A
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Liquid-crystal display devices of twisted nematic type
Assignee: Sharp Corp
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Filing: 1987-12-29
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Granted: 1989-08-15
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Expires: 2007-12-29
Abstract
Abstract A liquid-crystal display device of the twisted nematic type which comprises (1) a pair of electrode substrates facing each other, each being provided with an orientation membrane, the surface of which is treated by rubbing, and (2) a specific nematic liquid-crystal composition having a positive dielectric anisotropy containing a pyrimidine derivative of formula (I), ##STR1## wherein R 1 and R 2 are each a straight-chain alkyl group of 1 to 12 carbon atoms and containing an optically active substance, sandwiched between the two electrode substrates and arranged so that the axes of the liquid-crystal molecules will be twisted by an angle φ in the range of 210°≦φ≦300°, which shows excellent multiplex driving characteristics and suitable for use in display units of heavy-duty multiplex driving type.
Inventors
- 👤 Shyuichi Kozaki
- 👤 Yukiko Ichimura
- 👤 Yozo Narutako
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:20
CPC Classifications
C; C09; C09K; C09K19/00; C09K19/04; C09K19/06; C09K19/34; C09K19/3441; C09K19/345; C09K19/3458; C09K19/02; C09K19/0208; C09K19/42
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
154 words
A liquid-crystal display device of the twisted nematic type which comprises (1) a pair of electrode substrates facing each other, each being provided with an orientation membrane, the surface of which is treated by rubbing, and (2) a nematic liquid-crystal composition having a positive dielectric anisotropy and containing an optically active substance, sandwiched between the two electrode substrates and arranged so that the axes of the liquid-crystal molecules will be twisted by a prescribed angle φ, said nematic liquid-crystal composition comprising at least 5 weight % of liquid-crystals of a pyrimidine derivative represented by the following formula (I), ##STR36## wherein R 1 and R 2 are each a straight-chain alkyl group of 1 to 12 carbon atoms, and said angle φ being set at a level in the range of 210°≦φ≦300° under the condition of (φ/360°-1.4)<d/p<φ/360°, in which p represents the helical pitch of liquid-crystal molecules and d represents the thickness of liquid-crystal layer.
Claim 2
Dependent Claim
154 words
A liquid-crystal display device of the twisted nematic type which comprises (1) a pair of electrode substrates facing each other, each being provided with an orientation membrane, the surface of which is treated by rubbing, and (2) a nematic liquid-crystal composition having a positive dielectric anisotropy and containing an optically active substance, sandwiched between the two electrode substrates and arranged so that the axes of the liquid-crystal molecules will be twisted by a prescribed angle φ, said nematic liquid-crystal composition comprising at least 5 weight % of liquid-crystals of a pyrimidine derivative represented by the following formula (I), ##STR36## wherein R 1 and R 2 are each a straight-chain alkyl group of 1 to 12 carbon atoms, and said angle φ being set at a level in the range of 210°≦φ≦300° under the condition of (φ/360°-1.4)<d/p<φ/360°, in which p represents the helical pitch of liquid-crystal molecules and d represents the thickness of liquid-crystal layer.
Claim 3
Dependent Claim
31 words
The display device of claim 1 in which the nematic liquid-crystal composition comprises the liquid-crystal of pyrimidine derivative (I), nematic liquid-crystals having large positive dielectric anisotropy and an optically active substance.
Claim 4
Dependent Claim
49 words
The display device of claim 2 in which the nematic liquid-crystal having large positive dielectric anisotropy includes a cyano compound selected from the group consisting of compounds of the formula: ##STR37## wherein R 3 to R 8 are each a straight-chain alkyl group of 1 to 7 carbon atoms.
Claim 5
Dependent Claim
71 words
The display device of claim 2 in which the optically active substance includes at least one compound selected from the group consisting of compounds of the formulae: ##STR38## wherein 2MB* denotes a radical of C 2 H 5 -C*H(CH 3 )-CH 2 --in which C* stands for an asymmetric carbon atom, and a compound of those represented by the formula: ##STR39## wherein X is --C1, --OCOC 7 H 17 or ##STR40##
Claim 6
Dependent Claim
29 words
The display device of claim 1 in which the formula (I) pyrimidine derivative is contained in an amount of 10 to 70 weight % in the nematic liquid-crystal composition.
Claim 7
Dependent Claim
22 words
The display device of claim 5 in which the amount of the formula (I) pyrimidine derivative is 30 to 70 weight %.
Claim 8
Dependent Claim
19 words
The display device of claim 1 in which the orientation membrane is made of an inorganic or organic material.
Claim 9
Dependent Claim
21 words
The display device of claim 7 in which the inorganic material is SiO 2 and the organic material is a polyimide.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-14 | 1993-02-13 | 1993-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-14 | 1997-02-13 | 1997-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-14 | 2001-02-13 | 2001-08-15 | $7700.00 | Window Closed / Lapsed |