# US 9,519,085 B2 · Light diffusing sheet and backlight using same

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- Number: US 9,519,085 B2
- Document ID: US9519085B2
- Status: Granted
- Kind: B2
- Application number: 13/516,743
- Filed: 2010-12-16
- Published: 2012-10-11
- Granted: 2016-12-13
- Earliest claimed: 2009-12-17
- Assignees: Kimoto Co., Ltd.
- Applicants: Hiroshi Yokota; Shingo Ohsaku
- Inventors: Hiroshi Yokota; Shingo Ohsaku
- Web page: https://patentgrep.com/patent/US9519085B2

## CPC

- G02B 5/0242: {by means of dispersed particles}
- G02B 5/0221: {the surface having an irregular structure (G02B5/0226 takes precedence)}
- G02F 1/133606: {including a specially adapted diffusing, scattering or light controlling members}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- 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 light diffusing sheet can include a diffusion layer. The diffusion layer has a surface profile that satisfies certain conditions.

## Claims

### Claim 1

A light diffusing sheet comprising a diffusion layer, wherein the diffusion layer has a surface profile that satisfies the following conditions 1 and 2:
Condition 1: a condition under which when the skewness (JIS B0601, 2001) of a roughness curve as determined by two-dimensional surface profile measurement is represented by Rsk, Rsk is negative,
Condition 2: a condition under which when the mean height (JIS B0601, 2001) of roughness curve elements as determined by two-dimensional surface profile measurement is represented by Rc, Rc is not less than 6.0 μm, wherein
the total thickness of the light diffusing sheet is 80 μm or less,
wherein the diffusion layer includes a diffusing agent and a binder resin; and
wherein the diffusing agent has an average particle size from 1 to 10 μm.

### Claim 2 (depends on 1)

The light diffusing sheet according to claim 1, wherein the diffusion layer has a surface profile that satisfies the following conditions 3 and 4:
Condition 3: a condition under which when the peak count (JIS B0601, 2001) as determined by two-dimensional surface profile measurement is represented by Pc, Pc is not less than 150, and
Condition 4: a condition under which when the ten-point average roughness (JIS B0601, 2001) as determined by two-dimensional surface profile measurement is represented by Rzjis, Rzjis is not less than 12.0 μm.

### Claim 3 (depends on 1)

The light diffusing sheet according to claim 1, which is used in a backlight in which a high brightness LED light source is incorporated.

### Claim 4 (depends on 1)

A backlight comprising at least a light source, an optical plate for light guiding or diffusion disposed adjacent to the light source, and a light diffusing sheet disposed on the light exit side of the optical plate, wherein the light diffusing sheet is the light diffusing sheet according to claim 1.

### Claim 5 (depends on 4)

The backlight according to claim 4, wherein the light source is an LED light source.

### Claim 6 (depends on 4)

The backlight according to claim 4, wherein the light source includes a high brightness LED light source.

### Claim 7 (depends on 2)

The light diffusing sheet according to claim 2, which is used in a backlight in which a high brightness LED light source is incorporated.

### Claim 8 (depends on 3)

A backlight comprising at least a light source, an optical plate for light guiding or diffusion disposed adjacent to the light source, and a light diffusing sheet disposed on the light exit side of the optical plate, wherein the light diffusing sheet is the light diffusing sheet according to claim 3.

### Claim 9 (depends on 2)

A backlight comprising at least a light source, an optical plate for light guiding or diffusion disposed adjacent to the light source, and a light diffusing sheet disposed on the light exit side of the optical plate, wherein the light diffusing sheet is the light diffusing sheet according to claim 2.

### Claim 10 (depends on 9)

The backlight according to claim 9, wherein the light source is an LED light source.

### Claim 11 (depends on 1)

The light diffusing sheet according to claim 1,
wherein the content of the diffusing agent is from 100 to 200 parts by weight with respect to 100 parts by weight of the binder resin.