EP0382460A2
Expired / Lapsed
EP
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Liquid crystal display device
Assignee: Sharp Corp
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Filing: 1990-02-06
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Granted: —
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Expires: 2010-02-06
Abstract
Abstract The invention relates to a liquid crystal display device wherein phase difference plates (2,4) equal in retardation value, being composed of uniaxial polymer film or the like, are disposed symmetrically at the front side and back side of an STN liquid crystal panel (3), and the wavelength dispersion is made nearly ideal. As a result, the phase difference is compensated over the entire wavelength region, and the azimuth angles of the exit ellipsoidal polarization are aligned, so that a colorless display and high contrast may be realized at the same time.
Inventors
- 👤 Hiroshi Ohnishi
- 👤 Toshiyuki Yoshimizu
- 👤 Masakazu Wada
- 👤 Hiroshi Kuwagaki
- 👤 Toshimichi Katsube
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 10:26
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/13363; G02F1/133637; G02F1/137; G02F1/139; G02F1/1396; G02F1/1397; G02F2413/00; G02F2413/02; G02F2413/08
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
175 words
A liquid crystal display device, relating to a supertwisted nematic liquid crystal display device, composed by sequentially laminating an upper polarizer plate (1), a first phase difference plate (2), an STN liquid crystal panel (3), a second phase difference plate (4), and a lower polarizer plate (5), wherein the retardation values of the first phase difference plate (2) and the second phase difference plate (4) are equal to each other, and the first phase difference plate (2) and the second phase difference plate (4) are symmetrically disposed with respect to the STN liquid crystal panel (3), or in the relation of ϑ₁ + ϑ₂ = 180°, wherein ϑ₁ is the angle formed by the liquid crystal molecular orientation axis of the upper substrate composing the STN liquid crystal panel (3) and the optical axis of the first phase difference plate (2), ϑ₂ is the angle formed by the liquid crystal molecular orientation axis of the lower substrate composing the STN liquid crystal panel (3) and the optical axis of the second phase difference plate (4).
Claim 2
Dependent Claim
175 words
A liquid crystal display device, relating to a supertwisted nematic liquid crystal display device, composed by sequentially laminating an upper polarizer plate (1), a first phase difference plate (2), an STN liquid crystal panel (3), a second phase difference plate (4), and a lower polarizer plate (5), wherein the retardation values of the first phase difference plate (2) and the second phase difference plate (4) are equal to each other, and the first phase difference plate (2) and the second phase difference plate (4) are symmetrically disposed with respect to the STN liquid crystal panel (3), or in the relation of ϑ₁ + ϑ₂ = 180°, wherein ϑ₁ is the angle formed by the liquid crystal molecular orientation axis of the upper substrate composing the STN liquid crystal panel (3) and the optical axis of the first phase difference plate (2), ϑ₂ is the angle formed by the liquid crystal molecular orientation axis of the lower substrate composing the STN liquid crystal panel (3) and the optical axis of the second phase difference plate (4).
Claim 3
Dependent Claim
32 words
A liquid crystal display device according to claim 1, wherein the retardation values of the first phase difference plate (2) and the second phase difference plate (4) are 330 to 500 nm.
Claim 4
Dependent Claim
32 words
A liquid crystal display device according to claim 1, wherein the retardation values of the first phase difference plate (2) and the second phase difference plate (4) are 330 to 420 nm.
Claim 5
Dependent Claim
18 words
A liquid crystal display device according to claim 1, wherein both ϑ₁ and ϑ₂ are greater than 45°.
Claim 6
Dependent Claim
16 words
A liquid crystal display device according to claim 1, wherein both ϑ₁ and ϑ₂ are 90°.
Claim 7
Dependent Claim
34 words
A liquid crystal display device according to claim 1, wherein the first phase difference plate (2) and the second phase difference plate (4) are respectively composed of a single or plural uniaxial polymer film.
Claim 8
Dependent Claim
166 words
A liquid crystal display device according to claim 1, wherein relating to a liquid crystal display device using an STN liquid crystal panel (3) with known twist angle and retardation value, supposing the retardation values of the first phase difference plate (2) and the second phase difference plate (4) to be Rel individually, the effective retardation values due to the first phase difference plate (2) and the second phase difference plate (4) to be Re2, and the angle formed by the optical axes of the first phase difference plate (2) and the second phase difference plate (4) to be ϑ, from the graph showing the correlation of Re (panel) and Rel, an approximate value of Rel is selected, and from nRe2 = Re (panel) x 3/2 (n=1 or 2), an approximate value of Re2 is calculated, and from Re2 = 2Relcos ϑ, an approximate value of ϑ is calculated, and accordingly the first phase difference plate (2) and the second phase difference plate (4) are disposed.
References Cited (Backward Citations)
No citation records indexed.
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