US4097121A
Expired / Lapsed
US
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Liquid-crystal display with bistable cholesteric liquid-crystal layer and method of making the same
Assignee: Siemens AG
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Filing: 1976-09-14
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Granted: 1978-06-27
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Expires: 1996-09-14
Abstract
Abstract A liquid-crystal display incorporating a pair of spaced carrier plates separating a layer of liquid-crystal material, both of the plates having a set of selection conductors on their inner surfaces, defining a display matrix of visual elements, one or both sets of a selection conductors having dielectric layers on the respective conductors, forming marginal electrodes surrounding each individual visual element, the marginal electrodes being produced by a simultaneous masking and etching operation on the dielectric layer and associated conductor.
Inventors
- 👤 Miroslav Tauer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:02
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/13731; G02F1/133; G02F1/1333; G02F1/1343; G02F1/134309; G02F1/134336
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
301 words
A liquid crystal display for the representation of visual images comprising two carrier plates having therebetween in a hermetically sealed arrangement, a layer of cholesteric liquid crystal with a homeotripic wall orientation, each of said carrier plates having a conductor array on its inner surface facing the other, said liquid crystal having at least in a certain frequency range a positively anisotropic susceptibility, and at field strengths equal to or greater than a first threshold value E cn taking on a homeotropically-nematic texture, in which it remains as long as the applied field is greater than a second lower threshold value E nc , said conductor arrays having at least one separately operable conductor, the electrodes of at least one of the two carrier plates having a dielectric layer thereon, the dielectric constant of which is smaller than that of the LC layer, said dielectric layer being so dimensioned relative to the associated electrode that marginal portions of the latter are exposed, respective marginal portions defining a plurality of picture segments, with said marginal portions defining a marginal zone each of which operatively encircles a respective display segment, which marginal zone during operation of the liquid crystal display, each have a minimum field strength E r , equal or greater than E cn , in the liquid-crystal layer, and simultaneously a holding field strength E h , lower than E cn , at the location of the picture segment enclosed by the marginal zone, during operation of the liquid crystal display, the marginal edges of the combined electrode and dielectric layers forming an approximately flat edge wall composed of the lower electrode edge and the upper aligned dielectric edge, such edge wall being inclined in the form of a beveled edge whereby the electrode edge extends outwardly beyond the dielectric edge.
Claim 2
Dependent Claim
301 words
A liquid crystal display for the representation of visual images comprising two carrier plates having therebetween in a hermetically sealed arrangement, a layer of cholesteric liquid crystal with a homeotripic wall orientation, each of said carrier plates having a conductor array on its inner surface facing the other, said liquid crystal having at least in a certain frequency range a positively anisotropic susceptibility, and at field strengths equal to or greater than a first threshold value E cn taking on a homeotropically-nematic texture, in which it remains as long as the applied field is greater than a second lower threshold value E nc , said conductor arrays having at least one separately operable conductor, the electrodes of at least one of the two carrier plates having a dielectric layer thereon, the dielectric constant of which is smaller than that of the LC layer, said dielectric layer being so dimensioned relative to the associated electrode that marginal portions of the latter are exposed, respective marginal portions defining a plurality of picture segments, with said marginal portions defining a marginal zone each of which operatively encircles a respective display segment, which marginal zone during operation of the liquid crystal display, each have a minimum field strength E r , equal or greater than E cn , in the liquid-crystal layer, and simultaneously a holding field strength E h , lower than E cn , at the location of the picture segment enclosed by the marginal zone, during operation of the liquid crystal display, the marginal edges of the combined electrode and dielectric layers forming an approximately flat edge wall composed of the lower electrode edge and the upper aligned dielectric edge, such edge wall being inclined in the form of a beveled edge whereby the electrode edge extends outwardly beyond the dielectric edge.
Claim 3
Dependent Claim
19 words
A liquid-crystal display according to claim 1, wherein each conductor strip has a transverse cross-section approximating an isosceles trapezoid.
Claim 4
Dependent Claim
27 words
A liquid-crystal display according to claim 2, wherein a straight line approximating said inclined edge wall forms an angle of at least 10° with the plate normal.
Claim 5
Dependent Claim
18 words
A liquid-crystal display according to claim 1, characterized in that the dielectric layer consists of SiO 2 .
Claim 6
Dependent Claim
18 words
A liquid-crystal display according to claim 3, characterized in that the dielectric layer consists of SiO 2 .
Claim 7
Dependent Claim
39 words
A liquid-crystal display according to claim 1 in the form of a display matrix, wherein the conductors of each plate are in the form of parallel strips, those on one plate extending normal to those on the other path.
Claim 8
Dependent Claim
39 words
A liquid-crystal display according to claim 5, in the form of a display matrix, wherein the conductors of each plate are in the form of parallel strips, those on one plate extending normal to those on the other path.
Claim 9
Dependent Claim
41 words
A liquid-crystal display according to claim 1 wherein, with a plate spacing of 10 to 20 μum and an electrode-coating thickness of 0.1 to 0.5 μum, the dielectric layer is 0.6 to 3μum thick, and preferably consists of SiO 2 .
Claim 10
Dependent Claim
42 words
A liquid-crystal display according to claim 7 wherein, with a plate spacing of 10 to 20 μum and an electrode-coating thickness of 0.1 to 0.5 μum, the dielectric layer is 0.6 to 3 μum thick, and preferably consists of SiO 2 .
Claim 11
Independent Claim
255 words
A method of producing a liquid crystal display, for the representation of visual images, which comprises two carrier plates having therebetween, in hermetically sealed arrangement, a layer of cholesteric liquid crystal with a homeotropic wall orientation, each of said carrier plates having a conductor array on its inner surface facing the other, said liquid crystal having at least in a certain frequency range a positively anisotropic susceptibility, and at field strengths equal to or greater than a first threshold value E cn taking on a homeotropically-nematic texture, in which it remains as long as the applied field is greater than a second lower threshold value E nc , the electrodes of at least one of the two carrier plates having a dielectric layer thereon, with the dielectric layer being so dimensioned relative to the associated electrode that marginal portions of the latter are exposed, whereby the electrode edge extends outwardly beyond the dielectric edge, comprising the steps of coating one face of each carrier plate with an electrode coating and at least one electrode surface with a dielectric layer, whereby at least one carrier plate is thereby provided with a double layer, photo-masking upon the layers of the respective plates the display electrode configuration, and etching the respective plates, simultaneously etching the double layer until the desired edge formation is produced, thereafter assembling the two carrier plates in operative spaced relation, enclosing the marginal edge portions therebetween to form a chamber, filling the chamber with a liquid crystal material, and finally sealing the filled chamber.
Claim 12
Independent Claim
255 words
A method of producing a liquid crystal display, for the representation of visual images, which comprises two carrier plates having therebetween, in hermetically sealed arrangement, a layer of cholesteric liquid crystal with a homeotropic wall orientation, each of said carrier plates having a conductor array on its inner surface facing the other, said liquid crystal having at least in a certain frequency range a positively anisotropic susceptibility, and at field strengths equal to or greater than a first threshold value E cn taking on a homeotropically-nematic texture, in which it remains as long as the applied field is greater than a second lower threshold value E nc , the electrodes of at least one of the two carrier plates having a dielectric layer thereon, with the dielectric layer being so dimensioned relative to the associated electrode that marginal portions of the latter are exposed, whereby the electrode edge extends outwardly beyond the dielectric edge, comprising the steps of coating one face of each carrier plate with an electrode coating and at least one electrode surface with a dielectric layer, whereby at least one carrier plate is thereby provided with a double layer, photo-masking upon the layers of the respective plates the display electrode configuration, and etching the respective plates, simultaneously etching the double layer until the desired edge formation is produced, thereafter assembling the two carrier plates in operative spaced relation, enclosing the marginal edge portions therebetween to form a chamber, filling the chamber with a liquid crystal material, and finally sealing the filled chamber.
Claim 13
Dependent Claim
64 words
A method according to claim 10, wherein the margin of the dielectric layer is etched to a greater degree than the electrode edge whereby the marginal edges of the combined electrode and dielectric layers form an approximately flat edge wall composed of the lower electrode edge and the upper aligned dielectric edge, which edge wall is inclined in the form of a beveled edge.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-06-26 | 1981-12-26 | 1982-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-26 | 1985-12-26 | 1986-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-26 | 1989-12-26 | 1990-06-27 | $7700.00 | Window Closed / Lapsed |