# US 12,000,560 B2 · Illumination systems for reflective displays

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- Number: US 12,000,560 B2
- Document ID: US12000560B2
- Status: Granted
- Kind: B2
- Application number: 18/205,808
- Filed: 2023-06-05
- Published: 2023-11-02
- Granted: 2024-06-04
- Earliest claimed: 2012-04-20
- Assignees: E Ink Corporation
- Applicants: E Ink Corporation
- Inventors: Dirk Hertel; Richard J. Paolini, Jr.; Benjamin Harris Paletsky; Stephen J. Telfer
- Web page: https://patentgrep.com/patent/US12000560B2

## CPC

- F21S 43/30: characterised by reflectors
- F21S 43/26: {Refractors, transparent cover plates, light guides or filters not provided in groups F21S43/235 - F21S43/255}
- F21S 43/2605: {Refractors}
- F21V 14/003: {by interposition of elements with electrically controlled variable light transmissivity, e.g. liquid crystal elements or electrochromic devices}
- G03B 21/10: Projectors with built-in or built-on screen
- G03B 21/14: Details
- F21S 41/645: {by electro-optic means, e.g. liquid crystal or electrochromic devices}
- G02F 1/167: by electrophoresis
- G02F 1/1677: Structural association of cells with optical devices, e.g. reflectors or illuminating devices
- G03B 21/608: Fluid screens
- G03B 21/62: Translucent screens
- F21S: NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## 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

### Claim 1

A display system, comprising:
a reflective display for rendering a first image viewable through a viewing surface; and
a projection system including a light source, one or more optical elements, and a light modulator for rendering a second image viewable in reflection on the viewing surface, the second image having approximately the same width and height as the first image and being superimposed on the first image to form a composite image, wherein the first image has w1 pixels in the width dimension and h1 pixels in the height dimension, where h1>w1, and the second image has w2 pixels in the width dimension and h2 pixels in the height dimension, where h2<w2.

### Claim 2 (depends on 1)

The display system of claim 1, wherein the reflective display is an electrophoretic display, an electro-wetting display, an electrochromic display, a rotating bichromal display, or a reflective liquid crystal display.

### Claim 3 (depends on 2)

The display system of claim 2, wherein the reflective display is an electrophoretic display including an electrophoretic medium 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.

### Claim 4 (depends on 3)

The display system of claim 3, wherein the electrically charged particles and the fluid are confined within a plurality of capsules or microcells.

### Claim 5 (depends on 1)

The display system of claim 1, wherein pixels of the second image rendered by the projection system are mapped 1:1 onto pixels of the first image rendered by the reflective display.

### Claim 6 (depends on 1)

The display system of claim 1, wherein the first image comprises achromatic image components and the second image comprises chromatic image components.

### Claim 7 (depends on 1)

The display system of claim 1, wherein the light source comprises a color light-emitting diode (LED) or a solid state color laser source.

### Claim 8 (depends on 1)

The display system of claim 1, wherein the projection system comprises a pico-projector.

### Claim 9 (depends on 1)

The display system of claim 1, wherein the reflective display comprises an electronic document reader or an electronic book.

### Claim 10 (depends on 1)

The display system of claim 1, wherein the light modulator is in a landscape orientation, and the second image viewable in reflection on the viewing surface is in a portrait orientation.

### Claim 11 (depends on 1)

The display system of claim 1, wherein a long axis of the light modulator is projected onto a short axis of the viewing surface.

### Claim 12 (depends on 1)

The display system of claim 1, wherein the frame rate of the reflective display differs from that of the projection system by at least 10 percent.

### Claim 13

A display system, comprising:
a reflective display for rendering a first image viewable through a viewing surface; and
a projection system including a light source, one or more optical elements, and a light modulator for rendering a second image viewable in reflection on the viewing surface, the second image having approximately the same width and height as the first image and being superimposed on and in registration with the first image to form a composite image, wherein pixels of the second image are mapped 1:1 onto pixels of the first image, and wherein the frame rate of the reflective display differs from that of the projection system by at least 10 percent.

### Claim 14 (depends on 13)

The display system of claim 13, wherein the projection system operates at about 60 frames per second and the reflective display operates at about 15 frames per second to enhance video contrast.

### Claim 15 (depends on 13)

The display system of claim 13, wherein the reflective display is an electrophoretic display including an electrophoretic medium 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.