Method and apparatus for improved color filter saturation

• US 10,203,436 B2
• Filed: 05/15/2014
• Issued: 02/12/2019
• Est. Priority Date: 05/22/2013
• Status: Active Grant

• Current Assignee: WUXI Clearink Limited
• Original Assignee: Clearink Displays, Inc.
• Inventors: Whitehead, Lorne A.
• Primary Examiner(s): Beatty, Collin X
• Application Number:
  US14/891,783
• Publication Number:
  US 20160231475A1
• Time in Patent Office: 1,734 Days
• Field of Search: 359230
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• 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: G02B 5/128 transparent spheres being embedded in matrix
• CPC Class Codes: G02B 5/13 plural curved refracting elements forming part of a unitary body
• CPC Class Codes: G02B 5/136 plural reflecting elements forming part of a unitary body G02B5/124 takes precedence
• CPC Class Codes: G02B 5/201 in the form of arrays
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1677 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type
• CPC Class Codes: G09G 3/344 based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167

Abstract

A reflective image display comprising of a reflection enhancing layer comprising of a plurality of approximately spherical indentations is placed adjacent a sheet comprising of a plurality of hemispherical protrusions. The radii of curvature of the spherical indentations substantially coincides with the center of curvature of the adjacently located hemispheres to enhance the white paper-like appearance of the display while efficiently enabling optional color filters to yield saturated color.

Claims

1. A totally internally reflective display with a brightness enhancing structure, the display comprising:

a first optically transparent sheet;

at least one electrode layer;

a second optically transparent sheet having a surface further comprising of a plurality of convex or hemi-spherical protrusions, each of the convex or hemi-spherical protrusions having a dark pupil region;

a reflection enhancing layer that substantially semi-retro-reflects an incoming ray of light that passes through the dark pupil regions of the convex or hemi-spherical protrusions;

at least one optical modulation layer wherein light is prevented or allowed to pass, the optical modulation layer including a cavity having one or more electrophoretic particles suspended in a medium; and

a voltage source to controllably modulate the optical layer;

wherein the outgoing light ray is substantially parallel to the incoming light ray.

2. A reflective display according to claim 1, wherein the voltage source is switchable to:

apply a voltage across the optical modulation layer of one polarity to allow light to pass; and

apply a voltage across the optical modulation layer of a second polarity to prevent light from passing.

3. The reflective display according to claim 2, wherein the reflection enhancing layer comprises an array of approximately spherical indentations, whereby each spherical indentation further comprises a radius of curvature that substantially coincides with the center of curvature of the convex or hemi-spherical protrusion located substantially above the array of approximately spherical indentations.

4. The reflective display according to claim 3, wherein the ratio of the radius of curvature of a spherical indentation to the radius of curvature of a hemi-spherical protrusion is about 0.5 to 5.

5. The reflective display according to claim 3, wherein the ratio of the radius of curvature of a spherical indentation to the radius of curvature of a hemi-spherical protrusion is about 1 to 3.

6. The reflective display according to claim 3, wherein the ratio of the radius of curvature of a spherical indentation to the radius of curvature of a hemi-spherical protrusion is about 1 to 2.

7. The reflective display according to claim 3, wherein the optical modulating layer is comprised of an electrophoretic medium further comprised of a plurality of suspended electrostatically charged light absorbing electrophoretically mobile particles.

8. The reflective display according to claim 3, wherein the optical modulating layer is comprised of an electro-wetting system.

9. The reflective display according to claim 3, wherein the optical modulating layer is comprised of a micro-electromechanical system.

10. The reflective display according to claim 7, wherein:

movement of the electrophoretically mobile particles by application of a voltage of one polarity creates a light state; and

movement of the electrophoretically mobile particles by application of a voltage of a second polarity creates a dark state.

11. The reflective display according to claim 1, further comprising a color filter array comprised of red, green and blue sub-pixels.

12. The reflective display according to claim 1, further comprising a color filter array comprised of cyan, magenta and yellow sub-pixels.

13. The reflective display according to claim 1, wherein at least one electrode layer comprises a thin film transistor array.

14. The reflective display according to claim 1, wherein at least one electrode layer comprises a patterned array.

15. The reflective display according to claim 1, further comprising spacers or spacer beads.

16. The reflective display according to claim 7, wherein the electrophoretically mobile particles are comprised of an organic material or an inorganic material or a combination of an inorganic and organic material.

17. The reflective display according to claim 7, wherein the electrophoresis medium is comprised of a hydrocarbon or a fluorocarbon or a combination of a hydrocarbon and fluorocarbon.

18. The reflective display according to claim 1, wherein the optically transparent sheet having a surface comprising of a plurality of convex protrusions or hemi-spherical protrusions may be formed by any one of embossing, etching, molding, self-assembly, printing, lithography or micro-replication.

19. The reflective display according to claim 3, wherein the reflection enhancing layer comprised of a plurality of spherical indentations may be formed by any one of embossing, etching, molding, self-assembly, printing, lithography or micro-replication.

20. The reflective display according to claim 1, further comprising a front light.

21. An electronic book reader, portable computer, tablet computer, wearable, cellular telephone, smart card, sign, watch, shelf label, flash drive, outdoor billboards or outdoor signs comprising a display according to claim 1.