Backlight and liquid crystal display using same
View Patent ↗A backlight unit 1 includes a plurality of light emitting devices 2 constituted with, for example, LED lamps, and an optical sheet 4 disposed on light emission surface 2 b sides of the light emitting devices 2 . The light emission surface sides of the plural light emitting devices are joined to the optical sheet 4 via joining layers 5 . The backlight unit 1 satisfies a condition of n 1 ≦n 2 ≦n 3 , where n 1 is a refractive index of the optical sheet 4 , n 2 is a refractive index of the joining layer 5 , and n 3 is a refractive index of the light emitting device 2.
1. A backlight unit, comprising:
a plurality of light emitting devices having semiconductor light emitting elements;
an optical sheet disposed on light emission surface sides of the plurality of light emitting devices; and
joining layers intervening between light emission surfaces of the plurality of light emitting devices and the optical sheet,
wherein a condition of n 1 ≦n 2 ≦n 3 is satisfied, where n 1 is a refractive index of the optical sheet, n 2 is a refractive index of the joining layer, and n 3 is a refractive index of the light emitting device.
2. The backlight unit according to claim 1 ,
wherein the refractive index n 1 of the optical sheet is 1.3 or less, the refractive index n 2 of the joining layer is 1.4 or less, and the refractive index n 3 of the light emitting device is 2.48 or less.
3. The backlight unit according to claim 1 , further comprising
a base substrate to which non-light emission surfaces of the plurality of light emitting devices are joined.
4. The backlight unit according to claim 3 ,
wherein the plurality of light emitting devices are disposed on the base substrate in matrix; and
wherein the base substrate is disposed directly under a display device radiating light emitted from the plurality of light emitting devices.
5. The backlight unit according to claim 1 ,
wherein the joining layer is made of transparent resin having a thermosetting property.
6. The backlight unit according to claim 5 ,
wherein the transparent resin is silicone resin.
7. The backlight unit according to claim 1 ,
wherein the optical sheet has a reflection part provided on a non-joining part for the light emitting device in a surface to which the plurality of light emitting devices are joined.
8. The backlight unit according to claim 7 ,
wherein the reflection part is provided in 80% or more of the non-joining part for the light emitting device of the optical sheet.
9. The backlight unit according to claim 7 ,
wherein the reflection part has a reflectance of 80% or more.
10. The backlight unit according to claim 3 ,
wherein the base substrate has a through hole.
11. The backlight unit according to claim 10 ,
wherein the optical sheet has a reflection part provided on a non-joining part for the light emitting device in a surface to which the plurality of light emitting devices are joined; and
wherein the through hole is provided in a position facing the reflection part.
12. The backlight unit according to claim 3 ,
wherein the base substrate has a peripheral member disposed around the light emitting device.
13. The backlight unit according to claim 12 ,
wherein the peripheral member has a cylindrical shape or a cup shape; and
wherein part of the joining layer is filled inside the peripheral member.
14. The backlight unit according to claim 1 ,
wherein the light emitting device includes the semiconductor light emitting element, and a light emission part which is exited by light from the semiconductor light emitting element to emit white light.
15. The backlight unit according to claim 1 ,
wherein the semiconductor light emitting element comprises a light emitting diode or a laser diode.
16. The backlight unit according to claim 1 ,
wherein the optical sheet has at least one selected from a optical diffusion film, a light guide plate, and a prism film.
17. A liquid crystal display device, comprising:
a backlight unit according to claim 1 ; and
a liquid crystal display part disposed on a light emission surface side of the backlight unit.
18. The liquid crystal display device according to claim 17 ,
wherein the backlight unit comprises a base substrate having the plurality of light emitting devices disposed thereon in matrix; and
wherein the base substrate is disposed directly under the liquid crystal display part.
19. The liquid crystal display device according to claim 17 ,
wherein the backlight unit has as the optical sheet at least one selected from a optical diffusion film and a prism film.
20. The liquid crystal display device according to claim 17 , further comprising
at least one selected from a optical diffusion film and a prism film disposed between the optical sheet of the backlight unit and the liquid crystal display part.