# US 5,345,325 A · Sculptured light diffuser for enhancing brightness and uniformity of liquid crystal displays

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- Number: US 5,345,325 A
- Document ID: US5345325A
- Status: Granted
- Kind: A
- Application number: 08/040,941
- Filed: 1993-03-31
- Granted: 1994-09-06
- Earliest claimed: 1993-03-31
- Assignees: Rockwell International Corporation
- Inventors: Todd Twachtmann
- Web page: https://patentgrep.com/patent/US5345325A

## CPC

- G02F 1/133611: {including means for improving the brightness uniformity}
- G02F 1/133606: {including a specially adapted diffusing, scattering or light controlling members}
- 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 liquid crystal display having enhanced viewing brightness and brightness uniformity which utilizes a sculptured diffuser having a varied thickness characteristic where the thickness of the diffuser is reduced in areas where brightness of the display device is desired.

## Claims

### Claim 1

A visual display device comprising:
a visible light source;
means for reflecting a portion of said visible light in a direction toward a viewer;
means for filtering said visible light, disposed between said light source and the viewer, so that, said visible light can be transformed into a visual image having predetermined visual characteristics; and,
means for diffusing said light incident on said means for filtering, said means for diffusing being interposed between said means for filtering and said light source, and said means for diffusing further having a first thickness at a predetermined first area, a second thickness at a predetermined second area;
whereby, a visual display device, with enhanced overall light brightness, is provided by reducing the attenuation of light caused by the diffuser, at said first area is achieved without a reduction in the overall average light intensity across the display device.

### Claim 2 (depends on 1)

A device of claim 1 wherein said first area is an area at the periphery of said means for diffusing and said second area is an area at a central portion of said means for diffusing.

### Claim 3 (depends on 2)

A device of claim 2 wherein said first area is a cornet of said means for diffusing.

### Claim 4

An improved liquid crystal display comprising;
a fluorescent lamp;
a reflector;
a liquid crystal filter;
a diffuser disposed between said lamp and said liquid filter;
said diffuser having a frustum shape with a rectangular lamp side and a rectangular filter side, a first trapezoidal shaped side and a second trapezoidal shaped side; and,
said lamp side having a smaller surface area than said filter side.