EP0803758A2
Expired / Lapsed
EP
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Liquid crystal display
Assignee: Hitachi Ltd
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Filing: 1997-04-24
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Granted: —
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Expires: 2017-04-24
Abstract
Abstract A liquid crystal display featuring excellent visibility by satisfying both brightness and a contrast ratio comprises a projection optical system in which a polarizing plate, a phase plate 1 and a phase plate 2 in which a retardation of each of the phase plates and a gradient of wavelength dispersion of the retardation can be freely set, a liquid crystal layer, and a reflection plate are arranged in parallel and a transmitted light is reflected by the reflection plate. A gradient of one of the phase plates is set to an extremely steep gradient, a gradient of the other phase plate is set to an extremely flat gradient, and wavelength dispersion of a retardation composite value obtained from three of the liquid crystal layer and the two phase plates is approximated to a retardation curve expressed by a relational expression of (0.25 + 0.5n)λ, where (n) is an integer and λ is a wavelength (nm) of the transmitted light.
Inventors
- 👤 Osamu Itoh
- 👤 Shinichi Komura
- 👤 Ikuo Hiyama
- 👤 Shoichi Hirota
- 👤 Masaya Adachi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 11:46
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H04N9/3102; H04N9/3105; G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/133553; G02F1/133555; G02F1/13363; H04N9/3141; H04N9/315; H04N9/3158; G02F1/133637; G02F1/133638; G02F1/137; G02F1/139; G02F1/1393; G02F2201/00; G02F2201/40; G02F2413/00; G02F2413/02; H04N5/00; H04N5/74; H04N5/7416; H04N5/7441
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
162 words
A liquid crystal display in which a polarizing plate, two phase plates, an upper substrate, a liquid crystal layer, a drive device, and a lower substrate also serving as a reflection plate are sequentially laminated in a travelling direction of a transmitted light, and an absorption axis direction of the polarizing plate and an alignment direction of the liquid crystal layer, which is on the side adjacent to the polarizing plate have a non-parallel relation, characterized in that each of the two phase plates, which are set to phase plates 1 and 2, respectively, has wavelength dispersion of a retardation such that wavelength dispersion of a retardation composite value of the phase plates and the liquid crystal layer is substantially approximated to a retardation curve expressed by a relational expression of (0.25 + 0.5n)λ in a range of wavelengths from 400nm to 700nm of said transmitted light, where n is an integer and λ is a wavelength (nm) of the transmitted light.
Claim 2
Dependent Claim
203 words
A liquid crystal display in which a polarizing means, two phase plates, an upper substrate, a liquid crystal layer, a drive device, and a lower substrate also serving as a reflection plate are sequentially laminated in a travelling direction of a transmitted light, and an absorption axis direction of the polarizing means and an alignment direction of the liquid crystal layer, which is on the side adjacent to the polarizing direction have a non-parallel relation, characterized in that the polarizing means is a polarizing plate of a type in which a vibration direction of a transmission polarization component of the polarizing means rotates by 90° when a passing direction of the transmission light is changed, and each of the two phase plates, which are set to phase plates 1 and 2, respectively, has wavelength dispersion of a retardation, such that wavelength dispersion of a retardation composite value of the phase plates and the liquid crystal layer is set so as to be substantially approximated to a retardation curve expressed by a relational expression of (0.5n)λ in a range of wavelengths from 400nm to 700nm of said transmitted light, where n is an integer and λ is a wavelength (nm) of the transmitted light.
Claim 3
Dependent Claim
146 words
A liquid crystal display according to claim 1, characterized in that n is 0 or larger, a gradient of the wavelength dispersion of the retardation of the phase plate 1 is steeper than that of the liquid crystal layer and a gradient of the wavelength dispersion of the retardation of the phase plate 2 is flatter than that of the liquid crystal layer, the phase plate 1 is arranged so that a delay axis of the phase plate 1 perpendicularly crosses the alignment direction of the liquid crystal layer, and the phase plate 2 is arranged so that a delay axis of the phase plate 2 is in parallel with the alignment direction of the liquid crystal layer, and a retardation at the wavelength 550 (nm) of the phase plate 2 is larger than a retardation at the wavelength 550 (nm) of the phase plate 1.
Claim 4
Dependent Claim
143 words
A liquid crystal display according to claim 2, wherein n is 1 or larger, a gradient of the wavelength dispersion of the retardation of the phase plate 1 is steeper than that of the liquid crystal layer and a gradient of the wavelength dispersion of the retardation of the phase plate 2 is flatter than that of the liquid crystal layer, the phase plate 1 is arranged so that a delay axis of the phase plate 1 perpendicularly crosses the alignment direction of the liquid crystal layer, and the phase plate 2 is arranged so that a delay axis of the phase plate 2 is in parallel with the alignment direction of the liquid crystal layer, and retardation at the wavelength 550 (nm) of the phase plate 2 is larger than a retardation at the wavelength 550 (nm) of the phase plate 1.
Claim 5
Dependent Claim
96 words
A liquid crystal display according to claim 2, characterized in that n is equal to 0, a gradient of the wavelength dispersion of the retardation of the phase plate 1 is steeper than that of the liquid crystal layer and a gradient of the wavelength dispersion of the retardation of the phase plate 2 is flatter than that of the liquid crystal layer, and the phase plate 1 and the phase plate 2 are arranged so that a delay axis of each of the phase plates perpendicularly crosses an alignment direction of the liquid crystal layer.
Claim 6
Dependent Claim
148 words
A liquid crystal display according to claim 1 or 2, characterized in that n is smaller than 0, a gradient of the wavelength dispersion of the retardation of the phase plate 1 is steeper than that of the liquid crystal layer and a gradient of the wavelength dispersion of the retardation of the phase plate 2 is flatter than that of the liquid crystal layer, the phase plate 1 is arranged so that the delay axis of the phase plate 1 is in parallel with an alignment direction of the liquid crystal layer and the phase plate 2 is arranged so that the delay axis of the phase plate 2 perpendicularly crosses the alignment direction of the liquid crystal layer, and a retardation at the wavelength 550 (nm) of the phase plate 2 is larger than a retardation at the wavelength 550 (nm) of the phase plate 1.
Claim 7
Dependent Claim
181 words
A liquid crystal display having a projection optical system in which a polarizing plate, a phase plate, a liquid crystal layer, and a reflection plate are arranged in parallel and a transmitted light is reflected by the reflection plate, characterized in that the phase plate comprises phase plates 1 and 2 in which a retardation of each of the phase plates and a gradient of wavelength dispersion of the retardation can be freely set, and the gradient of the phase plate 1 is set so as to be larger than the gradient of the liquid crystal layer and the gradient of the phase plate 2 is set so as to be smaller than the gradient of the liquid crystal layer, and wavelength dispersion of a retardation composite value in the projection optical system which is a combination of the liquid crystal layer and the phase plates 1 and 2 is brought substantially close to a retardation curve expressed by a relational expression of (0.25 + 0.5n)λ where n is an integer and λ is a wavelength (nm) of the transmitted light.
Claim 8
Dependent Claim
63 words
A projection-type liquid crystal display comprising a drive device, a light source, an optical system, and a plurality of liquid crystal display elements, characterized in that the liquid crystal display element includes a liquid crystal layer, two substrates, and at least one phase plate, and retardations of the phase plates of the plurality of liquid crystal display elements are different from each other.
Claim 9
Dependent Claim
92 words
A projection-type liquid crystal display according to claim 8, wherein two substrate forming the liquid crystal display element have a display electrode and an alignment layer, the display electrode on the lower substrate also serves as a reflection plate, the display electrode on the lower substrate is connected to an active element, two substrates are arranged so as to face each other by sandwiching the liquid crystal layer, and a delay axis of the phase plate is in parallel with or perpendicularly crosses an adjacent alignment direction of the liquid crystal layer.
Claim 10
Dependent Claim
76 words
A projection-type liquid crystal display according to claim 9, wherein when n is an integer, a composite value of a retardation of the phase plate and a retardation of the liquid crystal layer which form the liquid crystal display element substantially satisfies 0.5nλ at least in a range of 100 nm in a visible wavelength range of λ = 400 nm to 700 nm when an arbitrary voltage VB is applied to the liquid crystal layer.
Claim 11
Dependent Claim
108 words
A projection-type liquid crystal display according to claim 10, wherein n is positive or 0, two of the phase plates are provided, wavelength dispersion of retardation of one phase plate is steeper than that of the liquid crystal layer and a delay axis of the phase plate is set so as to be in parallel with an adjacent alignment direction of the liquid crystal layer, and wavelength dispersion of retardation of the other phase plate is flatter than that of the liquid crystal layer and a delay axis of the other phase plate is set so as to perpendicularly cross an adjacent alignment direction of the liquid crystal.
Claim 12
Dependent Claim
105 words
A projection-type liquid crystal display according to claim 10, wherein (n) is negative, two phase plates are provided, wavelength dispersion of retardation of one of the phase plates is steeper than that of the liquid crystal layer and a delay axis of the phase plate is set so as to perpendicularly cross an adjacent alignment direction of the liquid crystal, and wavelength dispersion of retardation of the other phase plate is flatter than that of the liquid crystal layer and a delay axis of the other phase plate is set so as to be in parallel with an adjacent alignment direction of the liquid crystal.
References Cited (Backward Citations)
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