US 2003/0156403 A1Published application

Surface light source device and liquid crystal display

AssigneeEnplas Corporation

InventorShingo Ohkawa

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Abstract

Provided are surface light source devices and LCDs having isotropic and wide viewing angles. A surface light source device for illuminating an LCD comprises a light guide plate hiving a back face provided with a great number of micro-reflectors. Light beams P1, P2 representing an inner input light are inner-reflected by first and then second inner reflection faces or in inverse order, respectively to become a first and second inner output lights Q1 and Q2 which are non-parallel to each other, providing an emission having angular intensity characteristics showing two peaks. Peak splitting of the emission is dissolved by a light diffusion sheet disposed along an emission face of the light guide plate, causing an LCD panel to be illuminated by an isotropic and wide-view-angled illumination output light. The first and second inner reflection faces may be inclined oppositely and symmetrically to each other with respect to an imaginary reference plane that passes a valley bottom of a micro-reflector and extends perpendicularly to the emission face.

Claims4

Dependent claims

A surface light source device including a primary light source, a light guide plate supplied with light from said primary light source and a light diffusion member, wherein

said light guide plate has a an emission face provided by a major face, a back face provided by another major face opposite with said emission face and an incidence face for being supplied with light from said primary light source,
said back face being provided with a great number of projection-like micro-reflectors for light-travelling-direction-conversion,
each of said micro-reflectors has a conversion-output-portion including a first inner-reflection face and a second inner-reflection face which provide a valley in said light guide plate and meet each other as to give a valley bottom of said valley,
said valley being opened as to get deeper and wider toward a main light coming direction of an inner input light reaching the valley, thereby generating an inner output light containing a first inner output light and a second inner output light from said inner input light reaching the valley,
the first inner output light being produced through being inner-reflected by said first inner-reflection face and then by said second inner-reflection face,
the second inner output light being produced through being inner-reflected by said second inner-reflection face and then by said first inner-reflection face,
said first and second inner-reflection faces being inclined so that said first inner output light and said second inner output light are non-parallel and thereby said emission face provides a direction-split-emission having two emission intensity peaks,
said light diffusion member being disposed along said emission face in order to:input said direction-split emission having two intensity peaks thereto and to output an emission having a single emission intensity peak by dissolving said direction-split emission.

5 more elements

A liquid crystal display including a liquid crystal display panel and a surface light source device for illuminating said liquid crystal display panel, said surface light source device including a primary light source, a light guide plate supplied with light from said primary light source and a light diffusion member, wherein

said light guide plate has a an emission face provided by a major face, a back face provided by another major face opposite with said emission;
face and an incidence face for being supplied with light from said primary light source,
said back face being provided with a great number of projection-like micro-reflectors for light-travelling-direction-conversion,
each of said micro-reflectors has a conversion-output-portion including a first inner-reflection face and a second inner-reflection face which provide a valley in said light guide plate and meet each other as to give a valley bottom of said valley,
said valley being opened as to get deeper and wider toward a main light coming direction of an inner input light reaching the valley, thereby generating an inner output light containing a first inner output light and a second inner output light from said inner input light reaching the valley,
the first inner output light being produced through being inner-reflected by said first inner-reflection face and then by said second inner-reflection face,
the second inner output light being produced through being inner-reflected by said second inner-reflection face and then by said first inner-reflection face,
said first and second inner-reflection faces being inclined so that said first inner output light and said second inner output light are non-parallel and thereby said emission face provides a direction-split emission having two emission intensity peaks,
said light diffusion member being disposed along said emission face in order to input said direction-split emission having two intensity peaks thereto and to output an emission having a single emission intensity peak by dissolving said direction-split emission.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/319,535Filed 16 Dec 2002
Priority: JP 389666/200121 Dec 2001
Published: 21 Aug 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G02B 6/0028
Provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source: light…
G02B 6/0036
Provided on the surface of the light guide or in the bulk of it: 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
G02B 6/0061
Varying in density, size, shape or depth along the light guide: to provide homogeneous light output intensity
G02B 6/0068
Characterised by the light source being coupled to the light guide: arrangements of plural sources, e.g. multi-colour light sources