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US4009934A
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Electro-optic display devices and methods
Assignee: Eastman Kodak Co
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Filing: 1974-06-28
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Granted: 1977-03-01
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Expires: 1994-06-28
Abstract
Abstract An electro-optic display is provided which uses a liquid crystalline composition (a) having a positive, zero frequency dielectric anisotropy and (b) exhibiting a dielectric anisotropy inversion with increasing frequency of an applied field. Such a composition is subjected to an electric field of a first audio frequency and then subjected to a field of a second audio frequency of a magnitude sufficient to produce a dielectric anisotropy inversion in said composition. The resultant anisotropy changes allow the molecular orientation of the composition to be altered by the applied field thereby changing the optical properties of the composition.
Inventors
- 👤 Robert M. Goodwin
- 👤 Richard T. Klingbiel
- 👤 Hermann K. Bucher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:16
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/13306; C; C09; C09K; C09K19/00; C09K19/04; C09K19/06; C09K19/08; C09K19/10; C09K19/20; C09K19/2007; C09K19/2021; G02F1/137; G02F1/139; G02F1/1392
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
68 words
A method of scattering incident light comprising the steps of: 1. illuminating a liquid crystalline composition a. having a positive, zero frequency dielectric anisotropy, b. exhibiting a dielectric loss in the component of permittivity parallel to the optic axis of said composition, and c. exhibiting a dielectric anisotropy inversion when subjected to an electric field greater than the crossover frequency at which the dielectric anisotropy is zero; 2.
Claim 2
Independent Claim
68 words
A method of scattering incident light comprising the steps of: 1. illuminating a liquid crystalline composition a. having a positive, zero frequency dielectric anisotropy, b. exhibiting a dielectric loss in the component of permittivity parallel to the optic axis of said composition, and c. exhibiting a dielectric anisotropy inversion when subjected to an electric field greater than the crossover frequency at which the dielectric anisotropy is zero; 2.
Claim 3
Dependent Claim
56 words
alternately at a rate of change faster than about 20 changes per second subjected said composition to a. an electric field of a first frequency within the audio range below said crossover frequency, and b. an electric field of a second frequency within the audio range above said crossover frequency to provide transient molecular reorientation of
Claim 4
Dependent Claim
56 words
alternately at a rate of change faster than about 20 changes per second subjected said composition to a. an electric field of a first frequency within the audio range below said crossover frequency, and b. an electric field of a second frequency within the audio range above said crossover frequency to provide transient molecular reorientation of
Claim 5
Dependent Claim
25 words
said composition thereby scattering incident light. 2. The method as described in claim 1 wherein said crossover frequency is between 500 Hz and 10 kHz.
Claim 6
Dependent Claim
20 words
The method as described in claim 1 wherein said first frequency is about 0.5 to 0.1 times the crossover frequency.
Claim 7
Dependent Claim
20 words
The method as described in claim 1 wherein said second frequency is about 2 to 10 times the crossover frequency.
Claim 8
Independent Claim
148 words
A method of modulating light comprising the steps of: 1. illuminating an electro-optical device comprising: a. two closely-spaced, transparent, parallel conductive walls containing therebetween b. a cholesteric liquid crystalline composition i. having a positive, zero frequency dielectric anisotropy, ii. exhibiting a dielectric loss in ε.sub.∥, iii. exhibiting a dielectric anisotropy inversion when subjected to an electric field of a frequency greater than the crossover frequency at which the dielectric anisotropy is 0, and iv. having a planar cholesteric texture when no field is applied, 2. applying to said composition an electric field of a first frequency within the audio range below said crossover frequency and of a magnitude sufficient to alter the texture of said composition to a homeotropic nematic texture; and 3. applying an electric field of a second frequency within the audio range above said crossover frequency to orient said composition in a planar cholesteric texture.
Claim 9
Independent Claim
148 words
A method of modulating light comprising the steps of: 1. illuminating an electro-optical device comprising: a. two closely-spaced, transparent, parallel conductive walls containing therebetween b. a cholesteric liquid crystalline composition i. having a positive, zero frequency dielectric anisotropy, ii. exhibiting a dielectric loss in ε.sub.∥, iii. exhibiting a dielectric anisotropy inversion when subjected to an electric field of a frequency greater than the crossover frequency at which the dielectric anisotropy is 0, and iv. having a planar cholesteric texture when no field is applied, 2. applying to said composition an electric field of a first frequency within the audio range below said crossover frequency and of a magnitude sufficient to alter the texture of said composition to a homeotropic nematic texture; and 3. applying an electric field of a second frequency within the audio range above said crossover frequency to orient said composition in a planar cholesteric texture.
Claim 10
Dependent Claim
19 words
The method as described in claim 5 wherein said crossover frequency is between about 500 Hz to 10 kHz.
Claim 11
Dependent Claim
24 words
The method as described in claim 5 wherein said liquid crystalline composition is mesomorphic within the temperature range of about -20° to 100° C.
Claim 12
Dependent Claim
28 words
The method as described in claim 5 wherein said device is illuminated on one side and has a light absorbing layer on the side opposite that of illumination.
Claim 13
Dependent Claim
20 words
The method as described in claim 5 wherein said first frequency is about 0.5 to 0.1 times the crossover frequency.
Claim 14
Dependent Claim
20 words
The method as described in claim 5 wherein said second frequency is about 2 to 10 times the crossover frequency.
Claim 15
Dependent Claim
16 words
The method as described in claim 5 wherein said cholesteric composition comprises a chiral nematic material.
References Cited (Backward Citations)
US3731986A
Cited
US3857629A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-02-29 | 1980-08-30 | 1981-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-29 | 1984-08-30 | 1985-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-29 | 1988-08-30 | 1989-03-01 | $7700.00 | Window Closed / Lapsed |