Illumination apparatus comprising a light guide plate divided by wedge-shaped grooves having an apex angle of 15 degrees or less and a ratio of depth to thickness in a range of 0.4 to 0.7

• US 7,764,334 B2
• Filed: 06/29/2007
• Issued: 07/27/2010
• Est. Priority Date: 06/30/2006
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kitagawa, Toshitake, Okada, Naotada
• Primary Examiner(s): Schechter; Andrew
• Assistant Examiner(s): Kim; Dennis Y
• Application Number:
  US11/771,591
• Publication Number:
  US 20080030650A1
• Time in Patent Office: 1,124 Days
• Field of Search: 349/65, 362/613, 362/616, 362/619, 362/620, 362/612, 362/625, 362/626, 362/97.3
• US Class Current: 349/65
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays

Abstract

An illumination apparatus includes: a light guide plate composed of a plurality of aligned blocks; and a plurality of light sources, each being provided for one of the blocks and emitting light to the one block. A gap of 0.1 microns or more is formed in at least part of a region between the adjacent blocks. An inside of the gap serves as an air layer.

Claims

1. An illumination apparatus comprising:

a light guide plate composed of a plurality of aligned blocks; and

a plurality of light sources, each being provided for one of the blocks and emitting light to the one block,

the light guide plate being monolithically formed, and being divided into the plurality of aligned blocks by wedge-shaped grooves which are formed in the light guide plate, and are substantially parallel to a direction of the light,

a gap of 0.1 microns or more being formed in a part of a region between the adjacent blocks by forming the grooves, and

an inside of the gap serving as an air layer;

an apex angle of the wedge-shaped groove is 15 degrees or less, and

a ratio (depth of the wedge-shaped groove/thickness of the light guide plate) is in a range from 0.4 to 0.7.

2. The illumination apparatus according to claim 1, wherein a width of the gap is greater than a wavelength of a light emitted from the light sources.

3. The illumination apparatus according to claim 1, wherein the plurality of blocks are separate from each other, the adjacent blocks have faces opposed to each other, at least one of the faces is a rough surface having irregularities with Ra being 0.1 microns or more, and the one face abuts the other of the faces opposed to each other, whereby the gap of 0.1 microns or more is formed.

4. The illumination apparatus according to claim 1, wherein the plurality of blocks are separate from each other, and a spacer is provided between the blocks, whereby the gap of 0.1 microns or more is formed.

5. The illumination apparatus according to claim 1, wherein the light guide plate is formed by an injection molding.

6. The illumination apparatus according to claim 1, wherein

the plurality of aligned blocks are separate,

a protrusion is formed in one of faces opposed to each other in adjacent blocks and abuts other face,

a gap is formed in a region between the adjacent blocks other than a region that the protrusion abuts, and

a maximum width of the gap is 0.1 microns or more.

7. The illumination apparatus according to claim 1, wherein

each of the light sources includes a red light emitting diode configured to emit red light, green light emitting diode configured to emit green light, and a blue light emitting diode configured to emit blue light.

8. The illumination apparatus according to claim 7, further comprising a color mixing member provided between the block and its associated light sources, the color mixing member mixing the red light, the green light and the blue light.

9. A liquid crystal display apparatus comprising:

an illumination apparatus;

a liquid crystal panel irradiated with light from the illumination apparatus; and

a controller for applying a video signal to the liquid crystal panel and successively turning on the light sources in synchronization with timing of application of the video signal,

the illumination apparatus including;

a light guide plate composed of a plurality of aligned blocks; and

a plurality of light sources, each being provided for one of the blocks and emitting light to the one block,

the light guide plate being monolithically formed, and being divided into the plurality of aligned blocks by wedge-shaped grooves which are formed in the light guide plate substantially parallel to the direction of the light,

a gap of 0.1 microns or more being formed in a part of a region between the adjacent blocks by forming the grooves, and

an inside of the gap serving as an air layer;

an apex angle of the wedge-shaped groove is 15 degrees or less, and

a ratio (depth of the wedge-shaped groove/thickness of the light guide plate) is in a range from 0.4 to 0.7.

10. The liquid crystal display according to claim 9, wherein a width of the gap is greater than a wavelength of a light emitted from the light sources.

11. The liquid crystal display according to claim 9, wherein the plurality of blocks are separate from each other, the adjacent blocks have faces opposed to each other, at least one of the faces is a rough surface having irregularities with Ra being 0.1 microns or more, and the one face abuts the other of the faces opposed to each other, whereby the gap of 0.1 microns or more is formed.

12. The liquid crystal display according to claim 9, wherein the plurality of blocks are separate from each other, and a spacer is provided between the blocks, whereby the gap of 0.1 microns or more is formed.

13. The liquid crystal display according to claim 9, wherein the light guide plate is formed by an injection molding.

14. The liquid crystal display according to claim 9, wherein

the plurality of aligned blocks are separate,

a protrusion is formed in one of faces opposed to each other in adjacent blocks and abuts other face,

a gap is formed in a region between the adjacent blocks other than a region that the protrusion abuts, and

a maximum width of the gap is 0.1 microns or more.

15. The liquid crystal display according to claim 9, wherein

each of the light sources includes a red light emitting diode configured to emit red light, green light emitting diode configured to emit green light, and a blue light emitting diode configured to emit blue light,

the liquid crystal display further comprising a color mixing member provided between the block and its associated light sources, the color mixing member mixing the red light, the green light and the blue light.

16. The liquid crystal display apparatus according to claim 9, wherein

the illumination apparatus further includes a light receiver for detecting intensity of the light for each block, and

the controller controls the light sources using a detection result of the light receiver.