# US 2014/0152942 A1 · Surface light source device and liquid crystal display device

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- Number: US 2014/0152942 A1
- Document ID: US20140152942A1
- Status: Published application
- Kind: A1
- Application number: 14/079,254
- Filed: 2013-11-13
- Published: 2014-06-05
- Earliest claimed: 2012-12-04
- Assignees: Boe Technology Group Co., Ltd.
- Applicants: Boe Technology Group Co., Ltd.
- Inventors: KIMAN KIM; JAEGEON YOU
- Web page: https://patentgrep.com/patent/US20140152942A1

## CPC

- G02F 1/13362: {providing polarized light, e.g. by converting a polarisation component into another one}
- G02F 1/133543: {Cholesteric polarisers}
- G02F 1/133614: {using photoluminescence, e.g. phosphors illuminated by UV or blue light}
- 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

An surface light source device comprises: a light guide plate; a monochromatic light source located at a side of an incidence surface of the light guide plate; a cholesteric liquid crystal film, a λ/4 wave sheet and a wavelength converting thin film sequentially located at a side of an emission surface of the light guide plate. The surface light source device may improve the utilization rate of light and lower the costs.

## Claims

### Claim 1

A surface light source device, comprising:
a light guide plate;
a monochromatic light source located at a side of an incidence surface of the light guide plate; and
a cholesteric liquid crystal film, a λ/4 wave sheet and a wavelength converting thin film sequentially located at a side of an emission surface of the light guide plate.

### Claim 2 (depends on 1)

The surface light source device according to claim 1, wherein the cholesteric liquid crystal film and the wavelength converting thin film are respectively adhered to two sides of the λ/4 wave sheet.

### Claim 3 (depends on 1)

The surface light source device according to claim 1, wherein the cholesteric liquid crystal film, the λ/4 wave sheet, and the wavelength converting thin film are formed integrally, and the cholesteric liquid crystal film and the wavelength converting thin film are respectively located at two sides of the λ/4 wave sheet.

### Claim 4 (depends on 1)

The surface light source device according to claim 1, further comprising: a diffuse reflection sheet located at the other side of the light guide plate

### Claim 5 (depends on 1)

The surface light source device according to claim 1, wherein the monochromatic light source is a point light source or a linear light source.

### Claim 6 (depends on 1)

The surface light source device according to claim 1, wherein the monochromatic light source is a blue light source.

### Claim 7 (depends on 1)

The surface light source device according to claim 1, wherein the wavelength converting thin film comprises a single layer of fluorescent material or quantum dot material, or is in multi-layered structure formed by laminating multiple layers of fluorescent materials, or by laminating multiple layers of quantum dot materials.

### Claim 8 (depends on 1)

The surface light source device according to claim 1, wherein the surface light source device is of an edge lighting type or of a direct lighting type.

### Claim 9 (depends on 1)

A liquid crystal display device, comprising a surface light source device according to claim 1.