Illuminating arrangement with reflector having inclined irregularities or corrugations

• US 6,469,755 B1
• Filed: 10/29/1999
• Issued: 10/22/2002
• Est. Priority Date: 10/29/1998
• Status: Expired due to Fees

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Adachi, Masaya, Hiyama, Ikuo, Tsumura, Makoto
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGO, HUYEN LE
• Application Number:
  US09/429,954
• Time in Patent Office: 1,089 Days
• Field of Search: 349/62, 349/65, 349/67, 349/70, 349/71, 385/43, 385/146, 385/36
• US Class Current: 349/62
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/002 by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/133617 Illumination with ultraviolet light; Luminescent elements or materials associated to the cell
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

An illumination apparatus provides an improved light utilization efficiency and improved collimation. The illumination apparatus has a light guide, a collimating unit provided at least on one side of the light guide for collimating rays incident on the light guide, and a light source disposed in the vicinity of the collimating unit and surrounded by a reflector. Preferably, in order for the light guide to be able to emit collimated light uniformly from its emission surface, the light guide has inclined reflecting irregularities or stepwise reflecting plates which are provided directly or via an air gap on a back surface opposite to the emission surface thereof, wherein the inclined reflecting plates are specular-finished at least on the inclined portions.

Claims

1. An illumination arrangement comprising:

a light guide having a lower surface opposite to a light emission surface thereof, the lower surface and the light emission surface of the light guide intersecting one another across a mating edge, a reflector having inclined irregularities or corrugations disposed with respect to the lower surface of said light guide so as to reflect light in a direction toward the light emission surface, said inclined irregularities or said corrugations being specular finished;

a collimator provided adjacent at least one side of said light guide for collimating light incident on said light guide;

a light source juxtaposed to said collimator; and

a light source reflector which surrounds said light source.

6. An illumination arrangement according to any one of claims 1-5, wherein said collimator has an optical axis which is inclined relative to said light emission surface of said light guide.

7. An illumination arrangement according to any one of claims 1-5, wherein said light source is a cylindrical light source, and wherein said collimator has a first opening on a side thereof at least along a longitudinal direction of said cylindrical light source and a second opening on the side thereof facing said light guide, and a third opening in a center portion of said light guide which is narrower than the first and second openings.

8. An illumination arrangement according to any one of claims 1-5, wherein said light source is a cylindrical light source, and wherein said collimator has a first opening on a side thereof at least along a longitudinal direction of said cylindrical light source and a second opening on the side thereof facing said light guide, and a third opening in a center portion of said light guide which is narrower than the first and second openings, and wherein said collimator further has a light reflection surface provided partly on a wall of said wide opening facing said light source.

9. An illumination arrangement according to any one of claims 1-5, wherein said light source is a spot light source, said spot light source being disposed corresponding to each collimator, and wherein said collimator has an opening on the side thereof facing said light guide which is broader than an opening on the side which does not face said light guide.

10. An illumination apparatus according to any one of claims 1-3, further comprising a polarization converter interposed between said collimator and said light guide, wherein said light guide is a cylindrical light source, and said collimator has a first opening on a side thereof along a longitudinal direction of said cylindrical light source and a second opening on a side facing said light guide, and a third opening at a center portion of said collimator which is narrower than the first and second openings.

11. An illumination arrangement according to any of claims 1-3, further comprising a polarization converter interposed between said collimator and said light guide, wherein said light source is a spot light source, said spot light source being disposed for each one of said collimators, and wherein said collimator has an opening on the side thereof facing said light guide.

12. A liquid crystal display device provided with the illumination arrangement according to any one of claims 1-5 for displaying a picture through control of a polarization state, modes of scattering/transmittance, or absorption/transmission of light.

13. A liquid crystal display device according to claim 12, further comprising a screen disposed on the side of a display of said liquid crystal display device for spreading light of emission.

14. A liquid crystal display device according to claim 12, comprising a screen disposed on the side of display of a said liquid crystal display device for spreading light of emission and for absorbing external light and oblique incidence of light.

15. A liquid crystal display device according to claim 12, comprising a focus unit, a magnifying unit and a screen provided on the side of a display of a said liquid crystal display device.

16. A liquid crystal display device according to claim 12, wherein said light source emits a light the wavelength of which is 500 nm or less, and wherein phosphors that produce fluorescence light by irradiation by said light source are provided on the side of display of a said liquid crystal display element.

17. A liquid crystal display device comprising the illumination arrangement according to any one of claims 1-5 comprising:

a liquid crystal display element which includes;

a pair of transparent substrates spaced at a small distance, having transparent electrodes formed thereon counter-positioned to each other;

a liquid crystal layer interposed between said pair of transparent substrates; and

a voltage application device for applying a voltage in response to a picture signal to a pixel in a matrix formed by said transparent electrodes on said pair of transparent substrates;

a light source which emits light having a peak emission wavelength from 380 to 500 nm for illuminating said liquid crystal display element from a back side thereof; and

a wavelength converter disposed on an emission side of the liquid crystal layer of said liquid crystal display element, comprising phosphors of more than one species for converting light from said light source into a red or green light, said phosphors being arranged corresponding to respective pixels of said liquid crystal display element, wherein said liquid crystal display element has a polarizer disposed at least on the side of its light incidence such that a state of polarization of light which enters the liquid crystal layer is most efficiently utilized for the purpose of display.

18. A liquid crystal display device having the illumination arrangement according to any one of claims 1-5 disposed as a back light thereof, comprising:

a liquid crystal display element which includes;

a pair of transparent substrates, having transparent electrodes formed thereon so as to be counter-positioned and being spaced from each other by a small distance;

a liquid crystal layer interposed between said pair of transparent substrates; and

a voltage application device for applying a voltage in response to a picture signal to a pixel formed in a matrix by said transparent electrodes on said pair of transparent substrates;

further comprising a light source which emits a light having a peak emission spectrum of 430-480 nm for illuminating said liquid crystal display element as a back lighting; and

a wavelength converter comprising phosphors of more than one species arranged corresponding to respective pixels of said liquid crystal display element and disposed on the side of light emission of said liquid crystal layer for converting the light from said light source into a red or green colors, wherein said liquid crystal display element has a polarizer disposed on a light incidence side thereof for utilizing most efficiently the incidence light for the purpose of display by controlling a state of polarization thereof.

19. A liquid crystal display device having the illumination arrangement according to any one of claims 1-5 disposed as a back light thereof, comprising:

a liquid crystal display element which includes;

a pair of transparent substrates having transparent electrodes formed thereon so as to be counter-positioned to each other, the substrates being spaced by a small distance;

a liquid crystal layer interposed between said pair of transparent substrates; and

a voltage application device for applying a voltage in response to a picture signal to a pixel formed in a matrix by said transparent electrodes on said pair of transparent substrates;

further comprising a light source which emits a light having a peak emission spectrum of 380-500 nm for illuminating said liquid crystal display element as a back lighting; and

a wavelength converter comprising phosphors of more than one species arranged corresponding to respective pixels of said liquid crystal display element and disposed on the side of light emission of said liquid crystal layer for converting the light from said light source into a red or green colors;

wherein said light source is a fluorescent lamp juxtaposed to a side of a light guide formed into a plate; and

wherein said light guide has a structure to confine light which has entered from the side thereof by total reflection, and comprises an inclined reflector having a plurality of small irregularities or corrugations provided on a lower surface opposite to an emission surface of said light guide for emitting a collimated light therefrom, said collimated light being collimated at least in one direction by a change of a direction of its propagation on the reflector; and

further wherein a cholesteric liquid crystal film is interposed between said light guide and said liquid crystal display element as a polarization splitter, a retardation film is interposed between said cholesteric liquid crystal film and said liquid crystal display element as a first polarization converter, and a reflecting surface is provided in a lower direction of said light conductor as a second polarization converter for reflecting a portion of light reflected on said cholesteric liquid crystal film once again toward said cholesteric liquid crystal film such that at least a circularly polarized light which has entered in a vertical direction is reflected as a circularly polarized light having its direction of rotation reversed.

20. A liquid crystal display device according to claim 19, further comprising an optical path converter disposed between said light guide and said liquid crystal display element for converting non-polarized light at least in one direction into collimated light, wherein said optical path converter is disposed such that a direction of its optical conversion becomes orthogonal to a direction of said collimated light.

2. An illumination arrangement comprising a plurality of illumination apparatuses, each comprising:

a light guide having a lower surface opposite to a light emission surface thereof, the lower surface and the light emission surface of the light guide intersecting one another across a mating edge, a reflector having inclined irregularities or corrugations disposed with respect to the lower surface of said light guide as to reflect light in a direction toward the light emission surface, said inclined irregularities or said corrugations being specular finished;

a collimator provided adjacent at least one side of said light guide for collimating light incident on said light guide;

a light source juxtaposed to said collimator; and

a light source reflector which surrounds said light source.

3. An illumination arrangement comprising a plurality of illumination apparatuses, each comprising:

a light guide having a lower surface opposite to a light emission surface thereof, the lower surface and the light emission surface of the light guide intersecting one another across a mating edge, said light guide including a plurality of grooves provided on the light emission surface of said light guide, each groove having an inclined plane which is specular-finished;

a collimator provided at least;

on one side of said light guide for collimating light incident on said light guide;

a light source juxtaposed to said collimator; and

a light source reflector which surrounds said light source.

4. An illumination arrangement comprising a plurality of illumination-apparatuses, each comprising:

a light guide for emitting light therefrom in a band of rays of emission, said light guide having a lower surface opposite to a light emission surface thereof, the lower surface and the light emission surface of the light guide intersecting one another across a mating edge, a reflector having inclined irregularities or corrugations disposed with respect to the lower surface of said light guide as to reflect light in a direction toward the light emission surface thereof, said inclined irregularities or said corrugations being specular finished;

a polarization converter provided on said light guide;

a collimator provided at least on one side of said light guide for collimating light incident on said light guide;

a light source juxtaposed to said collimator; and

a light source reflector which surrounds said light source.

5. An illumination arrangement comprising a plurality of illumination apparatuses, each comprising:

a light guide having a lower surface opposite to a light emission surface thereof, the lower surface and the light emission surface of the light guide intersecting one another across a mating edge, said light guide including grooves formed in a light emission surface thereof, each groove having an inclined plane which is specular-finished for reflecting and emitting light in a band of rays of emission;

a polarization converter provided adjacent said light guide;

a collimator provided adjacent at least one side of said light guide for collimating light incident on said light guide;

a light source juxtaposed to said collimator; and

a light source reflector surrounding said light source.