EP0606940A2
Expired / Lapsed
EP
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Chloresteric polarizer and the manufacture thereof
Assignee: Koninklijke Philips NV
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Filing: 1994-01-06
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Granted: —
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Expires: 2014-01-06
Abstract
Abstract A broadband cholesteric polarizer is described, as well as a method of manufacturing such a polarizer. Said polarizer comprises an optically active layer of a polymer material having a cholesteric order, said material being oriented so that the axis of the molecular helix extends transversely to the layer. In accordance with the invention, the polarizer is characterized in that the pitch of the molecular helix in the layer is varied in such a manner that the difference between the maximum pitch and the minimum pitch is at least 100 nm. The optically active layers are preferably provided on substrates which bring about a conversion of circularly polarized light into linearly polarized light. Three different methods of manufacturing such broadband polarizers are described.
Inventors
- 👤 Dirk Jan C/O Int. Octrooibureau B.V. Broer
- 👤 Johan C/O Int. Octrooibureau B.V. Lub
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 18:23
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/30; G02B5/3016; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/133528; G02F1/133536; G02F1/133543; G02F1/1336; G02F1/13362
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
70 words
A cholesteric polarizer comprising an optically active layer of a polymer material having a cholesteric order, the material being oriented in such a manner that the axis of the molecular helix extends transversely to the layer, characterized in that the pitch of the molecular helix in the layer is varied in such a manner that the difference between the maximum pitch and the minimum pitch is at least 100 nm.
Claim 2
Dependent Claim
41 words
A cholesteric polarizer as claimed in Claim 1, characterized in that the pitch of the molecular helix increases substantially continuously from a minimum value at one surface of the layer to a maximum value at the other surface of the layer.
Claim 3
Dependent Claim
20 words
A cholesteric polarizer as claimed in Claim 1 or 2, characterized in that the polymer material forms a three-dimensional network.
Claim 4
Dependent Claim
67 words
A cholesteric polarizer as claimed in Claim 1, 2 or 3, characterized in that the optically active layer is present on a substrate of a stretched synthetic resin film, the degree of stretching and the thickness of the film being selected in such a manner that the optical retardation of the film is approximately 0.25 times the wavelength of the band reflected during operation of the polarizer.
Claim 5
Dependent Claim
94 words
A cholesteric polarizer as claimed in Claim 1, 2 or 3, characterized in that the optically active layer is present on a substrate of two stretched synthetic resin films of different composition, the directions of stretching of both films extending substantially transversely to each other and the degree of stretching of both films being selected in such a manner that, due to the difference in dispersion between the films, the nett retardation of the substrate is substantially equal to 0.25 times the wavelength over a substantial portion of the reflected band of the polarizer.
Claim 6
Independent Claim
91 words
A method of manufacturing a cholesteric polarizer as claimed in any one of the preceding Claims, characterized in that a mixture of chiral and nematogenic monomers, each having a different reactivity, is provided in the form of a layer between two parallel substrates, after which actinic radiation is applied in accordance with a radiation profile whose intensity varies over the layer, so that the mixture is polymerized to an optically active layer of polymer material having a cholesteric order, whereafter, if desired, the substrates are removed from the optically active layer.
Claim 7
Independent Claim
90 words
A method of manufacturing a cholesteric polarizer as claimed in any one of the Claims 1-5, characterized in that a mixture of chiral and nematogenic monomers, each having a different reactivity, is provided on a substrate in the form of a layer, after which actinic radiation is applied in accordance with a radiation profile whose intensity varies over the layer, so that the mixture is polymerised to an optically active layer of polymer material having a cholesteric order, whereafter, if desired, the substrate is removed from the optically active layer.
Claim 8
Dependent Claim
28 words
A method as claimed in Claim 6 or 7, characterized in that the number of reactive groups of the chiral monomer differs from that of the nematogenic monomer.
Claim 9
Dependent Claim
34 words
A method as claimed in Claim 6,7 or 8, characterized in that the mixture also comprises a dye having an absorption maximum whose wavelength corresponds substantially to the wavelength of the actinic radiation used.
Claim 10
Independent Claim
62 words
A method of manufacturing a cholesteric polarizer as claimed in any one of the Claims 1-5, characterized in that a surface of an optically active layer of polymerised liquid crystalline material having a cholesteric order is provided with a film of reactive monomers which cause a concentration gradient in the layer as a result of diffusion, after which the monomers are polymerised.
Claim 11
Dependent Claim
24 words
A method as claimed in Claim 10, characterized in that the film comprises a mixture of monomers having different diffusion rates in the layer.
Claim 12
Dependent Claim
25 words
A method as claimed in Claim 10 or 11, characterized in that at least a part of the monomers comprises two or more polymerisable groups.
Claim 13
Dependent Claim
37 words
A lighting device comprising a socket for an electric light source, a reflector and a cholesteric polarizer which is preferably provided with a quarter-wave plate, characterized in that a polarizer as claimed in Claims 1-5 is used.
References Cited (Backward Citations)
No citation records indexed.
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