# US 6,295,104 B1 · Front illuminating system with layer between light guide and LCD

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- Number: US 6,295,104 B1
- Document ID: US6295104B1
- Status: Granted
- Kind: B1
- Application number: 09/317,172
- Filed: 1999-05-24
- Granted: 2001-09-25
- Earliest claimed: 1998-05-26
- Assignees: Minebea Co., Ltd.
- Inventors: Motoji Egawa; Nobuhiro Sato; Shingo Suzuki
- Web page: https://patentgrep.com/patent/US6295104B1

## CPC

- 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}
- G02B 6/0041: {provided in the bulk of the light guide}
- G02B 6/005: {provided by one optical element, or plurality thereof, placed on the light output side of the light guide}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

In a transparent and spread illuminating apparatus 1, a light reflection pattern 7 consisting of the concave and convex is formed on the front surface 6 of a transparent substrate 2 so that the emission light is allowed to be uniformly irradiated on the face of the transparent substrate 2 regardless of a distance from a light source lamp 4, and the light is facially irradiated on a reflection type liquid crystal display element L. In addition, a transparent member 11 for changing the progressing direction of the light reflected from the transparent substrate 2 is disposed between the reflection type liquid crystal display element L and the transparent substrate 2 so as to be in close contact with both surfaces thereof. As a result, the degradation of the contrast which makes the observation of an image difficult and the generation of the moire pattern can be prevented.

## Claims

### Claim 1

A transparent and spread illuminating apparatus in which a transparent substrate is disposed so as to cover an observing surface of a reflection type liquid crystal display element, wherein a light source is disposed so as to be close to at least one side surface of said transparent substrate, a light reflection pattern including concave portions is formed on an observing surface of said transparent substrate, and a transparent member is disposed between said reflection type liquid crystal display element and said transparent substrate so as to be in close contact with the observing surface of the liquid crystal display element and a surface of the transparent substrate opposite to the observing surface of the transparent substrate, and wherein assuming that the refractive index of the transparent member is N1, and the refractive index of the transparent substrate is N2, the ratio of N2/N1 is in a range of 1.05≦N2/N1≦1.15.

### Claim 2 (depends on 1)

A transparent and spread illuminating apparatus as claimed in claim 1, wherein said transparent member is liquid, gel or an elastic material.

### Claim 3 (depends on 1)

A transparent and spread illuminating apparatus as claimed in claim 1, wherein the transparent member is formed of a light diffusing plate for diffusing the light.

### Claim 4 (depends on 3)

A transparent and spread illuminating apparatus as claimed in claim 3, wherein the light diffusing plate includes beads.

### Claim 5 (depends on 3)

A transparent and spread illuminating apparatus as claimed in claim 3, wherein the light diffusing plate is formed by adhering a layer including beads on a transparent substrate.