# US 6,295,162 B1 · Rear projection screen with optical sheet having irregularities caused by diffusing material smoothed with a transparent control layer

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- Number: US 6,295,162 B1
- Document ID: US6295162B1
- Status: Granted
- Kind: B1
- Application number: 09/125,292
- Filed: 1998-08-14
- Granted: 2001-09-25
- Earliest claimed: 1997-01-20
- Assignees: Dai Nippon Printing Co., Ltd.
- Inventors: Hideki Miyata
- Web page: https://patentgrep.com/patent/US6295162B1

## CPC

- G03B 21/625: Lenticular translucent screens
- 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)

## Abstract

A rear projection screen including a lenticular lens sheet with lenticular lenses for condensing or diffusing light and a transparent smooth layer having a surface roughness of 0 to 40 micrometers placed on the surface of the light-emerging side of the lenticular lens sheet. The rear projection screen can give an image that (1) is free from roughening, (2) has high fidelity gloss reproduction, and (3) has excellent contrast and sharpness.

## Claims

### Claim 1

A rear projection screen used for projecting very clear and distinct images comprising
an optical sheet including a diffusing material and having fine irregularities caused by said diffusing material on a light-emerging-side surface of said optical sheet; and
a transparent coating layer provided on at least an imaging-light-transmitting area in the light-emerging side surface of said optical sheet,
wherein said transparent coating layer smooths the imaging-light-transmitting area in the light-emerging-side surface of said optical sheet so that a surface roughness Ra of the imaging-light-transmitting area of said optical sheet is 0 to 40 μm.

### Claim 2 (depends on 1)

The rear projection screen according to claim 1, wherein the coating layer is a layer whose thickness d fulfills the equation d=λ/4n, where n is a refractive index of the coating layer, d is the thickness, and λ is a theoretical design wavelength.

### Claim 3 (depends on 1)

The rear projection screen according to claim 1, wherein the coating layer has a hardness that is higher than that of the optical sheet.

### Claim 4 (depends on 1)

The rear projection screen according to claim 1, further comprising a light-shielding layer provided on the light-emerging-side surface of the optical sheet, excluding the surface of the imaging-light-transmitting area.

### Claim 5 (depends on 4)

The rear projection screen according to claim 4, further comprising a transparent coating layer con the light-shielding layer.

### Claim 6 (depends on 1)

The rear projection screen according to claim 1, wherein said coating layer has a refractive index that is lower than the refractive index of said optical sheet.

### Claim 7 (depends on 1)

The rear projection screen according to claim 1, wherein said images are projected from a single-tube-light source.

### Claim 8

A rear projection screen used for projecting very clear and distinct images comprising
a plurality of optical sheets, at least the outermost optical sheet of said optical sheets including a diffusing material and having fine irregularities caused by said diffusing material on a light-emerging-side surface of said optical sheet; and
a transparent coating layer provided on at least an imaging-light-transmitting area in the light-emerging-side surface of at least the outermost optical sheet[, said transparent coating layer having a refractive index that is lower than the refractive index of the outermost optical sheet],
wherein said transparent coating layer smooths the imaging-light-transmitting area of the outermost optical sheet so that a surface roughness Ra of the imaging-light-transmitting area of the outermost optical sheet is from 0 to 0.40 μm.

### Claim 9 (depends on 8)

The rear projection screen according to claim 8, wherein the coating layer is a layer whose thickness d fulfills the equation d=λ/4n, where n is a refractive index of the coating layer, d is the thickness, and λ is a theoretical design wavelength.

### Claim 10 (depends on 8)

The rear projection screen according to claim 8, wherein the coating layer has a hardness that is higher than that of the outermost optical sheet.

### Claim 11 (depends on 8)

The rear projection screen according to claim 8, further comprising a light-shielding layer provided on the light-emerging-side surface of at least the outermost optical sheet, excluding the surface of the imaging-light-transmitting area.

### Claim 12 (depends on 11)

The rear projection screen according to claim 11, further comprising a transparent coating layer on the light-shielding layer.

### Claim 13 (depends on 8)

The rear projection screen according to claim 8, wherein said coating layer has a refractive index that is lower than the refractive index of said optical sheet.

### Claim 14 (depends on 8)

The rear projection screen according to claim 8, wherein said images are projected from a single-tube-light source.