US5579142A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid crystal display device having pleochroic dye and particular relationship of ratio d/po and twist angle
Assignee: Sharp Corp
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Filing: 1995-10-13
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Granted: 1996-11-26
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Expires: 2015-10-13
Abstract
Abstract A liquid crystal display device of the present invention includes: a pair of substrates, at least one of which is transparent; and a liquid crystal layer interposed between the pair of substrates, the liquid crystal layer having a helical structure including: a liquid crystal material having a positive dielectric constant anisotropy; a pleochroic dye; and at least one of a cholesteric liquid crystal material and a chiral agent as an optical active material, wherein the liquid crystal layer has a helical axis in a thickness direction of the liquid crystal layer, and longitudinal axes of liquid crystal molecules in a vicinity of the pair of substrates are substantially parallel to the substrates, a ratio of a natural pitch (p 0 ) and a thickness (d) of the liquid crystal layer of the helical structure satisfies a relationship: (2θ-π)/4π<d/p 0 ≦θ/2π, where a twisted angle of the helical structure is θ rad, and the twisted angle θ rad of the helical structure is within a range: 2π∞θ≦5π/2.
Inventors
- 👤 Yutaka Sawayama
- 👤 Masako Nakamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:23
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/13725; G02F2203/00; G02F2203/02
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
162 words
A liquid crystal display device comprising: a pair of substrates, at least one of which is transparent; and a liquid crystal layer interposed between the pair of substrates, the liquid crystal layer having a helical structure including: a liquid crystal material having a positive dielectric constant anisotropy; a pleochroic dye; and at least one of a cholesteric liquid crystal material and a chiral agent as an optical active material, wherein the liquid crystal layer has a helical axis in a thickness direction of the liquid crystal layer, and longitudinal axes of liquid crystal molecules in a vicinity of the pair of substrates are substantially parallel to the substrates, a ratio of a natural pitch (p 0 ) and a thickness (d) of the liquid crystal layer of the helical structure satisfies a relationship: (2θ-π)/4π<d/p 0 ≦θ/2π, where a twisted angle of the helical structure is θ rad, and the twisted angle θ rad of the helical structure is within a range: 2π≦θ≦5π/2.
Claim 2
Dependent Claim
162 words
A liquid crystal display device comprising: a pair of substrates, at least one of which is transparent; and a liquid crystal layer interposed between the pair of substrates, the liquid crystal layer having a helical structure including: a liquid crystal material having a positive dielectric constant anisotropy; a pleochroic dye; and at least one of a cholesteric liquid crystal material and a chiral agent as an optical active material, wherein the liquid crystal layer has a helical axis in a thickness direction of the liquid crystal layer, and longitudinal axes of liquid crystal molecules in a vicinity of the pair of substrates are substantially parallel to the substrates, a ratio of a natural pitch (p 0 ) and a thickness (d) of the liquid crystal layer of the helical structure satisfies a relationship: (2θ-π)/4π<d/p 0 ≦θ/2π, where a twisted angle of the helical structure is θ rad, and the twisted angle θ rad of the helical structure is within a range: 2π≦θ≦5π/2.
Claim 3
Dependent Claim
31 words
A liquid crystal display device according to claim 1, wherein one of the pair of substrates further includes an active element for switching a voltage applied to the liquid crystal layer.
Claim 4
Dependent Claim
37 words
A liquid crystal display device according to claim 2, wherein the active element is a non-linear element which is selected from a group consisting of a MIM, a diode, a varister, and a thin film transistor (TFT).
Claim 5
Dependent Claim
69 words
A liquid crystal display device according to claim 1, wherein one of the pair of substrates has a reflective pixel electrode which is provided so as to be in contact with the liquid crystal layer, and wherein the reflective pixel electrode consisting of an insulating film having a ragged surface and a metal reflective film which is formed so as to replicate the ragged surface of the insulating film.
Claim 6
Dependent Claim
21 words
A liquid crystal display device according to claim 1, wherein the twisted angle θ of the helical structure is about 9π/4.
Claim 7
Dependent Claim
46 words
A liquid crystal display device according to claim 1, wherein each of the pair of substrates has an alignment film which is formed such that a pretilt angle of the liquid crystal molecules constituting the liquid crystal layer is within a range of 5° to 20°.
Claim 8
Dependent Claim
69 words
A liquid crystal display device according to claim 2, wherein one of the pair of substrates has a reflective pixel electrode which is provided so as to be in contact with the liquid crystal layer, and wherein the reflective pixel electrode consisting of an insulating film having a ragged surface and a metal reflective film which is formed so as to replicate the ragged surface of the insulating film.
Claim 9
Dependent Claim
21 words
A liquid crystal display device according to claim 2, wherein the twisted angle θ of the helical structure is about 9π/4.
Claim 10
Dependent Claim
46 words
A liquid crystal display device according to claim 2, wherein each of the pair of substrates has an alignment film which is formed such that a pretilt angle of the liquid crystal molecules constituting the liquid crystal layer is within a range of 5° to 20°.
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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) | 1999-11-26 | 2000-05-27 | 2000-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-11-26 | 2004-05-27 | 2004-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-11-26 | 2008-05-27 | 2008-11-26 | $7700.00 | Window Closed / Lapsed |