Electro-optic display devices and methods
AssigneeEastman Kodak Company
InventorsRobert M. Goodwin, Richard T. Klingbiel, Hermann K. Bucher
Life of this patent
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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.
Claims11
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.
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 .epsilon..sub..parallel.,
- 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.
Dependencies are inferred from the claim text.