Surface emitting device, liquid crystal display, and optical sheet combination
View Patent ↗A surface emitting device includes a light emitter, a polarizer having a transmission axis along which light emerging from the light emitter is transmitted, and an optical sheet combination disposed between the light emitter and the polarizer and composed of a plurality of optical sheets. Each of the plurality of optical sheets includes an emergent surface for causing the emergent light to emerge, a spatial structure continuously arrayed on the emergent surface, a first optical axis parallel to an extension direction of the spatial structure and having a first refractive index, and a second optical axis parallel to an array direction of the spatial structure and having a second refractive index different from the first refractive index, wherein the first or second optical axis of a smaller one of the first and second refractive indices extends almost parallel to the transmission axis of the polarizer.
1. A surface emitting device comprising:
a light emitter;
a polarizer having a transmission axis along which light emerging from the light emitter is transmitted; and
an optical sheet combination disposed between the light emitter and the polarizer and composed of a plurality of optical sheets,
each of the plurality of optical sheets including:
an emergent surface for causing the emergent light to emerge therefrom,
a spatial structure continuously arrayed on the emergent surface,
a first optical axis parallel to an extension direction of the spatial structure and having a first refractive index, and
a second optical axis parallel to an array direction of the spatial structure and having a second refractive index different from the first refractive index, wherein the first or second optical axis of a smaller one of the first and second refractive indices extends almost parallel to the transmission axis of the polarizer.
2. The surface emitting device according to claim 1 , wherein the optical sheet combination includes:
a first optical sheet in which the first refractive index is smaller than the second refractive index; and
a second optical sheet in which the first refractive index is greater than the second refractive index.
3. The surface emitting device according to claim 2 , wherein the respective first and second optical sheets are composed of a resin sheet drawn in the extension direction of the spatial structure.
4. The surface emitting device according to claim 3 , wherein:
the first optical sheet is formed of a resin sheet in which the refractive index is smaller in a drawing direction; and
the second optical sheet is formed of a resin sheet in which the refractive index is greater in the drawing direction.
5. The surface emitting device according to claim 4 , wherein the first optical sheet is formed of a resin material selected from a group consisting of methacrylic resins, polystyrene resins, styrene-methyl methacrylate copolymers, and mixtures thereof.
6. The surface emitting device according to claim 4 , wherein the second optical sheet is formed of a resin material selected from a group consisting of Polyethylene Terephthalate, Polyethylene Naphthalate, mixtures thereof, and copolymers thereof.
7. The surface emitting device according to claim 2 , wherein the second optical sheet is disposed between the first optical sheet and the polarizer.
8. The surface emitting device according to claim 2 , wherein the first optical sheet is disposed between the second optical sheet and the polarizer, and has a third refractive index of an optical axis parallel to a thickness direction and greater than the first refractive index of the first optical sheet.
9. The surface emitting device according to claim 8 , wherein the third refractive index is substantially equal to the second refractive index of the first optical sheet.
10. The surface emitting device according to claim 9 , wherein the first optical axis of the first optical sheet is almost parallel to the transmission axis of the polarizer.
11. The surface emitting device according to claim 1 , wherein the spatial structure is a prism or a lenticular lens.
12. The surface emitting device according to claim 11 , wherein the spatial structure is formed of a birefringent liquid crystal material.
13. A liquid crystal display comprising:
a liquid crystal display panel;
a light emitter for illuminating the liquid crystal display panel;
a first polarizer disposed on a light incident side of the liquid crystal display panel and having a transmission axis along which light emerging from the light emitter is transmitted;
a second polarizer disposed on a light emergent side of the liquid crystal display panel; and
an optical sheet combination disposed between the first polarizer and the light emitter and composed of a plurality of optical sheets, each of the plurality of optical sheets including:
an emergent surface for causing the emergent light to emerge,
a spatial structure continuously arrayed on the emergent surface,
a first optical axis parallel to an extension direction of the spatial structure and having a first refractive index, and
a second optical axis parallel to an array direction of the spatial structure and having a second refractive index different from the first refractive index, wherein the first or second optical axis of a smaller one of the first and second refractive indices extends almost parallel to the transmission axis of the polarizer.
14. A surface emitting device comprising:
a light emitter for emitting a light which has polarization state whose intensity in the maximum direction is greater than one in the direction perpendicular to the maximum direction;
a polarizer having a transmission axis along which the light emerging from the light emitter is transmitted; and
an optical sheet combination disposed between the polarizer and the light emitter and composed of a plurality of optical sheets, each of the plurality of optical sheets including:
an emergent surface for outgoing the emitted light,
a spatial structure continuously arrayed on the emergent surface, a first optical axis parallel to an extension direction of the spatial structure and having a first refractive index, and
a second optical axis parallel to an array direction of the spatial structure and having a second refractive index different from the first refractive index, wherein the first or second optical axis of a smaller one of the first and second refractive indices extends almost parallel to the transmission axis of the polarizer.
15. An optical sheet combination, comprising:
a plurality of optical sheets each including:
an emergent surface for causing an emergent light from a light emitter;
a spatial structure continuously arrayed on the emergent surface;
a first optical axis parallel to an extension direction of the spatial structure and having a first refractive index; and
a second optical axis parallel to an array direction of the spatial structure and having a second refractive index different from the first refractive index,
wherein the first or second optical axis along of a smaller one of the first and second refractive indices extends almost parallel to a transmission axis along which light emerging from the light emitter is transmitted.