ILLUMINATION SYSTEMS FOR REFLECTIVE DISPLAYS

• US 20130278900A1
• Filed: 04/22/2013
• Published: 10/24/2013
• Est. Priority Date: 04/20/2012
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Hertel, Dirk, Paolini, Richard J. Jr., Telfer, Stephen J., Paletsky, Benjamin Harris, Sainis, Sunil Krishna, Mancini, Giovanni, Shea, Colleen, Biss, David Paul, Fantone, Stephen Dennis
• Granted Patent: US 10,190,743 B2
• Time in Patent Office: Days
• US Class Current: 353/28
• CPC Class Codes: F21S 41/645 by electro-optic means, e.g. liquid crystal or electrochromic devices
• CPC Class Codes: F21S 43/26 Refractors, transparent cover plates, light guides or filters not provided in groups F21S43/235 - F21S43/255
• CPC Class Codes: F21S 43/30 characterised by reflectors
• CPC Class Codes: F21V 14/003 by interposition of elements with electrically controlled variable light transmissivity, e.g. liquid crystal elements or electrochromic devices
• 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: G03B 21/10 Projectors with built-in or built-on screen
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/608 Fluid screens
• CPC Class Codes: G03B 21/62 Translucent screens

Abstract

A display device (30) comprises a reflective display (38) arranged to render a first image viewable through a viewing surface and a projection means (31-37) arranged to render a second image viewable in reflection on the viewing surface, the reflective display (38) and the projection means (31-37) being mounted on a common frame.

Claims

1. A display device comprising a reflective display arranged to render a first image viewable through a viewing surface and a projection means arranged to render a second image viewable in reflection on the viewing surface, the reflective display and the projection means being mounted on a common frame.

2. A display device according to claim 1 further comprising means for adjusting the intensity of the second image depending on the ambient illumination.

3. A display device according to claim 1 wherein the first image is an achromatic image and the second image is a chromatic image.

4. A display device according to claim 3 wherein the chromatic second image has a lower resolution than the achromatic first image.

5. A display device according to claim 1 wherein the first and second images are arranged to display video at different frame rates.

6. A display device according to claim 1 wherein the reflective display comprises a rotating bichromal member, electrochromic or electro-wetting material.

7. A display device according to claim 1 wherein the reflective display comprises an electrophoretic material comprising a plurality of electrically charged particles disposed in a fluid and capable of moving through the fluid under the influence of an electric field.

8. A display device according to claim 7 wherein the electrically charged particles and the fluid are confined within a plurality of capsules or microcells.

9. A display device according to claim 7 wherein the electrically charged particles and the fluid are present as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material.

10. A display device according to claim 7 wherein the fluid is gaseous.

11. A display device comprising a digital projector and a reflective surface mounted on a common frame, the digital projector comprising a light source, a projection lens and at least one additional optical element adapted to cause a projected image to be formed on the reflective surface, wherein the light passing from the light source through the projection lens is folded by more than 180 degrees in a plane containing the principal axis of the projection lens and a plane of symmetry of the at least one additional optical element before being reflected from the reflective surface.

12. A reflective display arranged to render a first image viewable through a viewing surface and a projection means comprising a light modulator arranged to render a second image viewable in reflection on the viewing surface, the first and second images being superimposed and having approximately the same width and height, the first image having w1 pixels in the width dimension and h1 pixels in the height dimension, where

h1>

w1

the second image having w2 pixels in the width dimension and h2 pixels in the height dimension, where

h2<

w2.

13. A display device comprising a reflective display arranged to render a first image viewable through a viewing surface and a projection means arranged to render a second image viewable in reflection on the viewing surface, wherein the frame rate of the reflective display differs from that of the projection means by at least 10 percent.

14. A method for rendering an image using a reflective display arranged to render a first image viewable through a viewing surface and a projection means arranged to render a second image viewable in reflection on the viewing surface, the method comprising:

(a) separating the image information into at least two components, a first component comprising at least luminance information and a second component comprising chrominance information; and

(b) using the first component to direct the first image and the second component to direct the second image.

15. An information display comprising a bistable reflective display having at least two separate reflective displays having display surfaces arranged to display different colors, and independently controllable light emitters arranged to direct light on to the two display surfaces.

16. An information display according to claim 15 in the form of a traffic light having three different colored electro-optic display areas illuminated by three different colored light emitters.

17. An information display according to claim 15 in the form of a traffic light having three monochrome electro-optic media areas illuminated by three different colored light emitters.

18. An information display according to claim 17 having three substantially white electro-optic media areas each having a plurality of light sources arranged substantially in a circle surrounding the electro-optic media area and arranged to illuminate the electro-optic media area.

19. An electrophoretic display comprising:

at least one front electrode through which an observer can view the display;

a layer of an electrophoretic medium, the electrophoretic medium comprising a fluid and two types of electrically charged particles disposed in the fluid and capable of moving through the fluid on application of an electric field to the fluid, one of the two types of particles being dark in color and the other being reflective and of a color different from that of the dark particles;

at least one rear electrode disposed on the opposed side of the layer of electrophoretic medium from the front electrode(s), the rear electrode(s) having a plurality of apertures extending therethrough; and

a light source disposed on the opposed side of the rear electrodes from the layer of electrophoretic medium and arranged to direct light through the layer of electrophoretic medium,

the display having a first optical state in which the dark particles lie adjacent the front electrode(s), so that the observer sees a dark color, a second optical state in which the reflective particles lie adjacent the front electrode(s), so that the observer sees the color of the reflective particles, and a third optical state is which the dark particles lie adjacent the rear electrode(s), the reflective particles the light source generates light, and the color of the reflective particles is visible to an observer.

20. A vehicle provided with at least one electrophoretic display according to claim 19.