# US 8,783,932 B2 · Backlight device and liquid crystal display apparatus

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- Number: US 8,783,932 B2
- Document ID: US8783932B2
- Status: Granted
- Kind: B2
- Application number: 13/641,052
- Filed: 2011-04-14
- Published: 2013-02-07
- Granted: 2014-07-22
- Earliest claimed: 2010-04-15
- Assignees: Mitsubishi Electric Corporation
- Applicants: Rena Nishitani; Tomohiro Sasagawa; Eiji Niikura; Kuniko Kojima; Jun Someya; Hiroaki Sugiura; Kazuhiko Tsutsumi; Akihiro Nagase
- Inventors: Rena Nishitani; Tomohiro Sasagawa; Eiji Niikura; Kuniko Kojima; Jun Someya; Hiroaki Sugiura; Kazuhiko Tsutsumi; Akihiro Nagase
- Web page: https://patentgrep.com/patent/US8783932B2

## CPC

- G02F 1/133615: {Edge-illuminating devices, i.e. illuminating from the side}
- G02B 6/0036: {2-D arrangement of prisms, protrusions, indentations or roughened surfaces}
- G02B 6/0061: {to provide homogeneous light output intensity}
- G02B 6/0068: {Arrangements of plural sources, e.g. multi-colour light sources}
- G02B 6/0076: {Stacked arrangements of multiple light guides of the same or different cross-sectional area}
- G02B 6/002: {by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces}
- G02B 6/003: {Lens or lenticular sheet or layer}
- G02F 1/133614: {using photoluminescence, e.g. phosphors illuminated by UV or blue light}
- G02F 1/133624: {characterised by their spectral emissions}
- 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
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A planar light source device includes a first light source for emitting a first light ray having a punctate spatial luminance distribution; a second light source for emitting a second light ray; a first spatial luminance distribution conversion portion for changing the first light ray to a linear spatial luminance distribution; a second spatial luminance distribution conversion portion for changing a spatial luminance distribution of the first and second light rays to a planar spatial luminance distribution; wherein the first light ray is a laser light; the second light ray has a divergence angle larger than the divergence angle of the first light ray when the first light ray is emitted from the first light source; and a slow-axis direction of the first light ray entering the second spatial luminance distribution conversion portion is parallel to an outgoing direction of the planar light.

## Claims

### Claim 1

A planar light source device comprising:
a first light source for emitting a first light ray which has a punctate spatial luminance distribution when the first light ray is emitted;
a second light source for emitting a second light ray;
a first spatial luminance distribution conversion portion for receiving the first light ray, changing the first light ray from the punctate spatial luminance distribution to a linear spatial luminance distribution, and then exiting the first light ray;
a second spatial luminance distribution conversion portion for receiving the first light ray having the linear spatial luminance distribution and the second light ray, changing a spatial luminance distribution of the received first light ray and a spatial luminance distribution of the received second light ray to a planar spatial luminance distribution, and then exiting the first light ray and the second light ray as planar light; and
an optical element disposed on an optical path from a light emitting surface of the first light source to a light incidence face of the second light source where the first light ray enters, the optical element spreading a divergence angle of the first light ray in the slow-axis direction on the optical path; wherein:
the first light ray is a laser light;
the second light ray has a divergence angle larger than the divergence angle of the first light ray when the first light ray is emitted from the first light source; and
a slow-axis direction of the first light ray entering the second spatial luminance distribution conversion portion is parallel to an outgoing direction of the planar light.

### Claim 2 (depends on 1)

The planar light source device according to claim 1, wherein a dominant wavelength of the first light ray is any wavelength in a wavelength band of 630 nm to 650 nm.

### Claim 3 (depends on 1)

A liquid crystal display apparatus comprising the planar light source device according to claim 1 as a backlight device.

### Claim 4 (depends on 1)

The planar light source device according to claim 1 wherein:
the first spatial luminance distribution conversion portion is a rectangular prism-shaped light guiding element;
the second spatial luminance distribution conversion portion is a plate-like light guide plate;
the light guiding element is disposed in a same plane as the light guide plate;
a light exit face of the light guiding element faces a light incidence face of the light guide plate;
the first light source is disposed to face at least one of two faces each formed by short sides formed in both ends of the light guiding element; and
the second light source is disposed so as to face one of side, faces formed by long sides and short sides of the light guiding element.

### Claim 5 (depends on 1)

The backlight device according to claim 1, wherein the first spatial luminance distribution conversion portion transmits the second light ray.

### Claim 6 (depends on 1)

The planar light source device according to claim 1 wherein a slow-axis direction of the first light ray entering the light guiding element is parallel to an outgoing direction of the planar light.