Auxiliary optics for a twisting ball display

• US 5,777,782 A
• Filed: 12/24/1996
• Issued: 07/07/1998
• Est. Priority Date: 12/24/1996
• 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): Ben, Loha
• Application Number:
  US08/777,225
• Time in Patent Office: 560 Days
• Field of Search: 359/298, 359/296, 345/107, 345/111, 427/214, 349/117, 349/188
• US Class Current: 359/296
• 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

Abstract

A gyricon or rotating-particle display having an auxiliary optical structure. The display includes a substrate with an optically transmissive window, a plurality of particles disposed in the substrate, and an optical focusing element optically coupled to the window. Each particle has an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the particle electrically responsive such that when the particle is rotatably disposed in an electric field while the electrical dipole moment of the particle is provided, the particle tends to rotate to an orientation in which the electrical dipole moment aligns with the field. A rotatable disposition of each particle is achievable while the particle is thus disposed in the substrate; when the particle is in this rotatable disposition, it is not attached to the substrate. Each particle, when rotatably disposed in the substrate, is disposable in first and second rotational orientations with respect to the optically transmissive window. Each particle provides a first optical modulation characteristic when disposed in its first orientation with respect to a flux of optical energy through the window, and further provides a second optical modulation characteristic when disposed in its second orientation with respect to a flux of optical energy through the window. The optical focusing element can be optically refractive; for example, it can include an array of converging lenses, such as a "fly'"'"'s-eye" array of microlenses. In this case, the particles can be disposed in an array that is registered with the lens array.

Claims

1. Apparatus comprising:

a substrate having an optically transmissive window;

a plurality of particles disposed in the substrate,

each particle having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the particle electrically responsive such that when the particle is rotatably disposed in an electric field while the electrical dipole moment of the particle is provided, the particle tends to rotate to an orientation in which the electrical dipole moment aligns with the field,

a rotatable disposition of each particle being achievable while said particle is thus disposed in the substrate, said particle, when in said rotatable disposition, not being attached to the substrate,

each particle, when rotatably disposed in the substrate, being disposable in first and second rotational orientations with respect to the optically transmissive window,

each particle providing a first optical modulation characteristic when disposed in said first orientation with respect to a flux of optical energy through the window,

each particle further providing a second optical modulation characteristic when disposed in said second orientation with respect to a flux of optical energy through the window; and

an optical focusing element optically coupled to the window.

2. The apparatus of claim 1 wherein the focusing element is optically refractive.

3. The apparatus of claim 2 wherein the optically refractive focusing element comprises an array of lenses.

4. The apparatus of claim 3 wherein the array of lenses comprises an array of converging lenses.

5. The apparatus of claim 3 wherein the array of lenses comprises an array of microlenses.

6. The apparatus of claim 3 wherein the particles are disposed in an array that is registered with the lens array.

7. The apparatus of claim 1 wherein the focusing element is structurally incorporated with the window in a single unit.

8. The apparatus of claim 1 wherein the focusing element is structurally distinct from the window and is fixedly attached to the window.

9. The apparatus of claim 1 wherein the substrate contains a dielectric fluid and the particles are disposed in the substrate in contact with the fluid.

10. The apparatus of claim 9 wherein the disposition of the particles in the fluid gives rise to the respective electrical dipole moments of the particles.

11. The apparatus of claim 9 wherein the dielectric fluid is an optically transmissive fluid having a first refractive index, and each particle comprises an optically transmissive region having a second refractive index.

12. The apparatus of claim 11 wherein each particle, when disposed in at least one of said first and second rotational orientations, produces a refractive effect when illuminated by a flux of optical energy through the substrate window, the refractive effect being produced as a result of said first and second indices of refraction differing from one another.

13. The apparatus of claim 11 wherein the optically transmissive region of each particle is associated with the first optical modulation characteristic, and each particle further comprises a region having a second optical property associated with the second optical modulation characteristic.

14. The apparatus of claim 1 wherein each particle comprises a spheroidal ball.

15. The apparatus of claim 1 wherein the ball has first and second hemispheres and

the first hemisphere of the ball is associated with a first zeta potential,

the second hemisphere of the ball is associated with a second zeta potential,

the first and second zeta potentials arising when the ball is disposed in a dielectric fluid, the first and second zeta potentials contributing to the electrical dipole moment.

16. The apparatus of claim 1 and further comprising means for producing an electric field to facilitate a rotation of at least one particle rotatably disposed in the substrate.

17. The apparatus of claim 16 wherein the electric field producing means comprises means for selectively addressing a set of particles rotatably disposed in the cavities, the set comprising at least one particle, by applying the electric field to the particles of the set and thereby facilitating a rotation of at least one particle of the set.

18. A device comprising:

a substrate comprising a matrix having a plurality of cavities, the substrate having an optically transmissive window;

an optically transmissive dielectric fluid having a first refractive index, disposed in the cavities of the matrix;

a plurality of optically anisotropic particles disposed in the cavities of the matrix in contact with the fluid, each particle having at least one optically transmissive region having a second refractive index,

each particle providing a first optical modulation characteristic when disposed in the fluid in a first orientation with respect to a flux of optical energy,

each particle further providing a second optical modulation characteristic when disposed in the fluid in a second orientation with respect to a flux of optical energy,

each particle having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the particle electrically responsive such that when the particle is rotatably disposed in an electric field while the electrical dipole moment of the particle is provided, the particle tends to rotate to an orientation in which the electrical dipole moment aligns with the field,

a rotatable disposition of each particle being achievable while said particle is thus disposed in the substrate, said particle, when in said rotatable disposition, not being attached to the substrate; and

an optical focusing element optically coupled to the window.

19. The apparatus of claim 18 and further comprising:

means for producing an electric field to facilitate a rotation of at least one particle

rotatably disposed in the substrate.

20. Apparatus comprising:

a substrate having an optically transmissive window, the substrate containing an optically transmissive dielectric fluid having a first refractive index;

a plurality of particles disposed in the substrate,

each particle having at least one optically transmissive region having a second refractive index,

each particle having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the particle electrically responsive such that when the particle is rotatably disposed in an electric field while the electrical dipole moment of the particle is provided, the particle tends to rotate to an orientation in which the electrical dipole moment aligns with the field,

a rotatable disposition of each particle being achievable while said particle is thus disposed in the substrate, said particle, when in said rotatable disposition, not being attached to the substrate,

each particle, when rotatably disposed in the substrate, being disposable in first and second rotational orientations with respect to the optically transmissive window,

each particle providing a first optical modulation characteristic when disposed in the fluid in a first orientation with respect to a flux of optical energy through the window,

each particle further providing a second optical modulation characteristic when disposed in the fluid in a second orientation with respect to a flux of optical energy through the window; and

an optical modulating element optically coupled to the window.

21. The apparatus of claim 20 wherein the optical modulating element comprises an optical focusing element.