US 6,211,929 B1 · Surface light source device of side light type and liquid crystal display

Abstract

A liquid crystal display includes a LCD panel and a surface light source device of side light type to illuminate the panel. The surface light source device comprises a guide plate having an emission face, a back face and an incidence face, a primary light source to supply light through the incidence face, and a reflection member disposed along the back face. The reflection member has an inner reflection face including a plurality of fine regions to control angular extension of illumination output. The fine regions are provided with scattering property which is different from that of the rest region. In cases where emission promoting power (scattering power) of the emission face falls according to distance from the incidence face, the reflection face of the reflection member is provided with scattering power which varies so as to tend to compensate said falling of emission promoting power. Fine regions are arranged in corner portions located at both ends of the incidence face to avoid short of emission. Employment of a reflection member provided with fine regions controls angular extension of illumination output, thereby preventing bright-dark unevenness from appearing under ranging view-angles.

Claims10

Dependent claims

A surface light source device of side light type comprising:

a guide plate having an emission face, a back face and an incidence face, said emission face being provided with a plurality of light scattering elements promoting emission from the emission face, the light scattering elements being distributed on the emission face with a covering rate varying depending on a position on the emission face;
a primary light source arranged to supply said guide plate with primary light through said incidence face;
and
a reflection member arranged along said back face so as to return light leaked from said back face into said guide plate,
wherein said reflection member has a reflection face which is directed to said back face and is provided with a plurality of fine regions having a scattering property which is different from that of a rest of the reflection face to control angular extension of illumination output, the fine regions being arranged so as to prevent the light scattering elements being distributed on the emission face from causing an angular extension of illumination output to vary depending on a position on the emission face.

2 more elements

A liquid crystal display including a liquid crystal display panel and a surface light source device of side light type for illuminating the liquid crystal display panel, the surface light source device comprising:

a guide plate having an emission face, a back face and ain incidence face, said emission face being provided with a plurality of light scattering elements promoting emission from the emission face, the light scattering elements being distributed on the emission face with a covering rate varying depending on a position on the emission face;
a primary light source arranged to supply said guide plate with primary light through said incidence face;
and
a reflection member arranged along said back face so as to return light leaked from said back face into said guide plate;
wherein said reflection member has a reflection face which is directed to said back face and is provided with a plurality of fine regions having a scattering property which is different from that of a rest of the reflection face to control angular extension of illumination output, the fine regions being arranged so as to prevent the light scattering elements being distributed on the emission face from causing an angular extension of illumination output to vary depending on a position on the emission face.

2 more elements

Dependencies are inferred from the claim text.

Surface light source device of side light type and liquid crystal display

Life of this patent

Surface light source device of side light type and liquid crystal display

Life of this patent

Abstract

Claims10