TIR switched flat panel display

• US 8,651,724 B2
• Filed: 12/31/2009
• Issued: 02/18/2014
• Est. Priority Date: 01/02/2009
• Status: Active Grant

• Current Assignee: Rambus Delaware
• Original Assignee: Rambus Delaware LLC (Rambus Inc.)
• Inventors: Richardson, Brian E.
• Primary Examiner(s): DZIERZYNSKI, EVAN P
• Application Number:
  US13/143,342
• Publication Number:
  US 20110267667A1
• Time in Patent Office: 1,510 Days
• Field of Search: 362/222.1, 362/615, 362/623, 362/624, 359/222.1
• US Class Current: 362/615
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]

Abstract

A flat panel display uses pixels (2060) that are turned on or off by the enabling or disabling total internal reflection, TIR, of a light guide (2010). A reflective surface (2070) directs the switched light towards the viewer. An optional mask may be employed to provide extremely high contrast ratios in low and in high ambient lighting conditions. The elements (2080) that enable TIR may be enabled quickly because of their small size and weight, resulting in a very fast switching speed. The fast switching speed allows colors to be generated and displayed in a sequential manner.

Claims

1. A light valve device comprising:

a light guide comprising a first surface, a second surface, and a third surface, wherein light enters through the first surface and propagates in the light guide by total internal reflection between the second surface and the third surface;

contact elements adjacent respective portions of the second surface, each contact element comprising a contact portion that faces the second surface, each contact element configured such that a portion of the light that is incident thereon is transmitted therethrough when the contact portion is in physical contact with the second surface;

a respective actuator coupled to each of the contact elements to selectively move the contact portion of the contact element into and out of physical contact with the second surface; and

a respective reflector positioned to receive the light transmitted through each of the contact elements when the contact element is in physical contact with the second surface, the reflector configured such that the light is reflected back into the light guide and exits the light guide through the third surface;

wherein the contact portions of the contact elements are small compared to the reflectors such that the contact elements function as quasi-point sources.

2. The light valve device of claim 1, wherein the actuator comprises an electrostatic actuator.

3. The light valve device of claim 1, wherein the actuator comprises a piezoelectric actuator.

4. The light valve device of claim 1, wherein the actuator comprises an electro-magnetic actuator.

5. The light valve device of claim 1, additionally comprising a control electronics panel located adjacent the second surface of the light guide, the control electronics panel comprising circuitry to control the actuators.

6. The light valve device of claim 5, wherein the actuators are secured to the control electronics panel.

7. The light valve device of claim 1, wherein the reflectors are generally spherical in shape.

8. The light valve device of claim 1, wherein the reflectors are generally aspheric in shape.

9. The light valve device of claim 1, wherein the contact portion of the contact element is index matched to the light guide.

10. The light valve device of claim 1, additionally comprising a region between the light guide and the contact elements outside the contact portions thereof, the region lower in refractive index than the light guide.

11. The light valve device of claim 10, wherein the region is configured as a hollow space between the light guide and each reflector.

12. The light valve device of claim 11, wherein the hollow space is substantially coextensive with the reflector.

13. The light valve device of claim 1, wherein:

each of the contact elements comprises a surface remote from the light guide; and

the respective reflector is located on the surface of the contact element.

14. The light valve device of claim 1, additionally comprising a mask plate of light absorbing material positioned adjacent the third surface of the light guide, the mask plate defining an aperture through which the light reflected by each reflector passes after exiting the light guide through the third surface.

15. The light valve device of claim 1 additionally comprising a diffusing layer located adjacent the third surface of the light guide.

16. The light valve device of claim 1, additionally comprising a light emitting diode light source positioned adjacent the first surface of the light guide.

17. A flat panel display comprising the light valve device of claim 1.