US4281903A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electro-optic passive display cell
Assignee: ETS SA A SWISS CORP
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Filing: 1979-02-01
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Granted: 1981-08-04
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Expires: 1999-02-01
Abstract
Abstract An electro-optic passive display device comprising a pair of plates having, as an active component between the plates, a mixture comprising a nematic liquid crystal possessing negative dielectric anisotropy, dichroic molecules and a chiralic compound capable of providing a helical structure to the active component, the chiralic compound concentration being selected to produce a pitch of the helix between 0.9d and 3d, "d" being the distance between plates, critical to ensure the formation of a helical structure only under the effect of an electric field and to provide a high contrast display.
Inventors
- 👤 Fereydoun Gharadjedaghi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:45
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/13725; G02F1/139; G02F1/1393; G02F1/1396
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
165 words
An electro-optic passive display cell comprising: two substantially parallel spaced plates; a frame sealed between said plates and defining a tight chamber therebetween; control electrodes arranged on the inner facing surfaces of said plates for providing an electric field therebetween; a coating of homeotropic alignment material covering said inner surfaces and said electrodes, an active component disposed in said chamber, said active component comprising a mixture of a nematic liquid crystal having a negative dielectric anisotropy, dichroic molecules and a chiralic compound capable of providing a helical structure to the said active component when an electric field is applied and a homeotropic structure in the absence of an applied electric field, the concentration of the said chiralic compound being selected to provide a pitch of the helical structure having a value substantially comprised between 0.9 and 3 times the distance between plates whereby satisfactory readable contrast is provided between areas under effect of an electric field and areas where such electric field effect is absent.
Claim 2
Dependent Claim
165 words
An electro-optic passive display cell comprising: two substantially parallel spaced plates; a frame sealed between said plates and defining a tight chamber therebetween; control electrodes arranged on the inner facing surfaces of said plates for providing an electric field therebetween; a coating of homeotropic alignment material covering said inner surfaces and said electrodes, an active component disposed in said chamber, said active component comprising a mixture of a nematic liquid crystal having a negative dielectric anisotropy, dichroic molecules and a chiralic compound capable of providing a helical structure to the said active component when an electric field is applied and a homeotropic structure in the absence of an applied electric field, the concentration of the said chiralic compound being selected to provide a pitch of the helical structure having a value substantially comprised between 0.9 and 3 times the distance between plates whereby satisfactory readable contrast is provided between areas under effect of an electric field and areas where such electric field effect is absent.
Claim 3
Dependent Claim
16 words
The display cell as claimed in claim 1, in which the nematic liquid crystal is methoxy-benzyliden-butyl-aniline.
Claim 4
Dependent Claim
17 words
The display cell as claimed in claim 1, in which said chiralic compound is cholesteryl oleyl carbonate.
Claim 5
Dependent Claim
149 words
An electro-optic passive display cell comprising: two substantially parallel spaced plates; a frame sealed between said plates and defining a tight chamber therebetween, control electrodes arranged on the inner facing surfaces of said plates for providing an electric field therebetween; and a coating of homeotropic alignment material covering said inner surfaces and the said electrodes, an active component disposed in said chamber, said component comprising a mixture of a nematic liquid crystal having a negative dielectric anisotropy, dichroic molecules and a chiralic compound capable of providing a helical structure to the said active component when an electric field is applied, the concentration of said chiralic compound selected to provide a pitch of the said helical structure having a value substantially comprised between 0.9 and 3 times the distance between plates whereby to be compatible with the spontaneous formation of a homeotropic structure in the absence of an electric field.
Claim 6
Dependent Claim
149 words
An electro-optic passive display cell comprising: two substantially parallel spaced plates; a frame sealed between said plates and defining a tight chamber therebetween, control electrodes arranged on the inner facing surfaces of said plates for providing an electric field therebetween; and a coating of homeotropic alignment material covering said inner surfaces and the said electrodes, an active component disposed in said chamber, said component comprising a mixture of a nematic liquid crystal having a negative dielectric anisotropy, dichroic molecules and a chiralic compound capable of providing a helical structure to the said active component when an electric field is applied, the concentration of said chiralic compound selected to provide a pitch of the said helical structure having a value substantially comprised between 0.9 and 3 times the distance between plates whereby to be compatible with the spontaneous formation of a homeotropic structure in the absence of an electric field.
Claim 7
Dependent Claim
16 words
The display cell as claimed in claim 4, in which the nematic liquid crystal is methoxy-benzyliden-butyl-aniline.
Claim 8
Dependent Claim
17 words
The display cell as claimed in claim 4, in which said chiralic compound is cholesteryl oleyl carbonate.
References Cited (Backward Citations)
DE2658568A1
Cited
US4143947A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-08-03 | 1985-02-02 | 1985-08-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-03 | 1989-02-02 | 1989-08-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-03 | 1993-02-02 | 1993-08-04 | $7700.00 | Window Closed / Lapsed |