Twisting ball panel display

• US 4,126,854 A
• Filed: 05/05/1976
• Issued: 11/21/1978
• Est. Priority Date: 05/05/1976
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Sheridon, Nicholas K.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US05/683,448
• Time in Patent Office: 930 Days
• Field of Search: 340/324 M, 340/366 R, 340/366 B, 340/378 R, 340/373, 350/160 R, 350/161 R, 350/161 S, 350/355, 350/362, 40/52 R
• US Class Current: 345/107
• CPC Class Codes: G02B 26/026 based on the rotation of particles under the influence of an external field, e.g. gyricons, twisting ball displays based on orientable dipolar particles G02F1/172; based on electrophoresis G02F1/167
• CPC Class Codes: G09F 9/372 the positions of the elements being controlled by the application of an electric field
• CPC Class Codes: H01H 2219/0023 Images formed with electrophoretic technology, e.g. by charged pigment particles rearranged by applied electric field, e.g. electronic paper or e-paper, active ink

Abstract

A display system in which the display panel is comprised of a plurality of particles which have an electrical anisotropy due to hemispherical surface coatings of different Zeta potential and their distribution in a volume of a dielectric liquid, and which also have an optical anisotropy due to the hemispherical surface coatings having different optical characteristics which may be due to the color or other optical properties of the hemispherical coatings. Under the action of an external electric field, the particles will rotate in accordance with their electrical anisotropy to provide a display in accordance with their optical anisotropy. The display has switching threshold and memory capabilities.

Claims

1. An addressable display device comprising:

a light transparent body having a plurality of optically anisotropic particles contained within dielectric liquid-filled cavities thereof, each of said particles having at least two dissimilar surfaces of contrasting optical characteristics and different Zeta potentials, the dissimilar surfaces of said particles and the distribution of said particles in said dielectric liquid causing said particles to have an electrical anisotropy, and

addressing means for applying an electric field across selected portions of said body whereby the particles contained within said selected portions of said body will rotate in accordance with their electrical anisotropy to provide a display in accordance with their optical anisotropy.

2. The display of claim 1 wherein each of said optically anisotropic particles has a surface portion which has a light absorbancy greater than the light absorbancy of another surface portion.

3. The display of claim 1 wherein each of said optically anisotropic particles has one surface portion of one color and another surface portion of a different color.

4. The display of claim 1 wherein said particles are spherical and said particles have at least one hemispherical coating that provides their optical anisotropy.

5. The display of claim 1 wherein said body is elastomeric.

6. The display of claim 1 wherein said cavities have an asymmetrical shape whereby said display has a threshold behavior.

7. The display of claim 6 wherein the asymmetrical shape of said cavities is produced by a piezoelectric device coupled to said body.

8. The display of claim 1 wherein said particles are of elliptical shape.

9. The display of claim 4 wherein said particles are rough in one hemisphere and smooth in the other hemisphere.

10. The display of claim 1 wherein threshold and memory capabilities are provided by additional means for preventing rotation of said particles within selected portions of said body until the field across said selected portions of said body exceeds a threshold value.

11. The display of claim 10 wherein said addressing means is comprised of a matrix of electrodes on opposite sides of said body and means for accessing the matrix crossover points.

12. The display of claim 11 wherein said additional means is an additional electrode on said opposite sides of said body and electrically isolated from said matrix electrodes, said additional electrodes having a higher resistance per unit length than said matrix electrodes, said additional electrodes being biased oppositely to the bias applied to said matrix electrodes.

13. The display of claim 10 wherein said particles are of a ferromagnetic material and said additional means is a sheet of a ferromagnetic material positioned adjacent one side of said body.

14. The display of claim 1 wherein said addressing means includes a photoconductive layer.

15. The display of claim 1 wherein said addressing means includes means for applying AC and DC fields across said body.

16. An addressable display device comprising:

a plurality of optically anisotropic particles contained within cavities of a light transparent body, said cavities being slightly larger than said particles such that said particles can have rotational movement but substantially no translational movement, said cavities also containing a liquid dielectric, each of said particles having at least two dissimilar surfaces of contrasting optical characteristics and different Zeta potentials, the dissimilar surfaces of said particles and the liquid dielectric being responsible for imparting an electrical anisotropy to said particles, and

addressing means for electrically addressing selected portions of said body to provide rotation of the particles within said cavities within said portions of said body to provide a display.

17. An addressable display device comprising:

a light transparent body having a plurality of cavities therein, at least some of said cavities each containing a single optically anisotropic particle and a dielectric liquid, each optically anisotropic particle having at least two dissimilar surfaces of contrasting optical characteristics and different Zeta potentials so that each particle further exhibits an electrical anisotropy when distributed in said dielectric liquid, and

addressing means for applying an electric field across selected portions of said body whereby the particles contained within said selected portions of said body will rotate in accordance with their electrical anisotropy to provide a display in accordance with their optical anisotropy.