Light source element with lateral, angular light injection

• US 7,688,400 B1
• Filed: 12/29/1999
• Issued: 03/30/2010
• Est. Priority Date: 12/29/1998
• Status: Expired due to Fees

• Current Assignee: OSRAM GmbH (Ams-Osram AG)
• Original Assignee: OSRAM GmbH (Ams-Osram AG)
• Inventors: Bachl, Bernhard, Brunner, Herbert, Schellhorn, Franz, Kirchberger, Gunter, Waitl, Gunter
• Primary Examiner(s): RUDE, TIMOTHY L
• Application Number:
  US09/868,364
• Time in Patent Office: 3,744 Days
• Field of Search: 349 61- 71
• US Class Current: 349/65
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02B 6/0001 specially adapted for lighting devices or systems lighting or signalling on vehicles using light guides B60Q1/00; lighting devices for vehicle dashboards B60Q3/10; lighting devices for vehicle interior using light guides B60Q3/62; lighting devices mounted on the vehicle rear part using light guides F21S43/235; measuring arrangements having light conducting pointers G01D13/265; illumination of liquid crystal displays G02F1/1336; illuminated signs G09F13/00
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G09F 9/35 being liquid crystals G09F9/302 takes precedence; liquid crystal materials C09K19/00; liquid crystal panels comprising a number of electrodes in a single cell per se G02F1/13

Abstract

A light source element is employed back-lighting of liquid crystal displays and that comprises an obliquely placed light exit face and/or light entry face. At its surfaces, the light waveguide is surrounded by reflectors into which suitable aperture regions are potentially formed. A plurality of light sources and/or a more direct view is provided and, thus, a corresponding increase of the luminance results. A method is also provided for the manufacture of a light source element with an integrated reflector.

Claims

1. A light source element, comprising:

a light waveguide and a light source, the light waveguide having a light exit face and a surface lying opposite the light exit face, the light exit face and the surface lying opposite the light exit face being connected by side faces,

wherein the surface lying opposite the light exit face and at least some portions of the side faces are covered and contacted with reflectors that at least one of reflect and diffusely return light;

wherein at least one projection is formed in at least one of the side faces of the light waveguide, each projection extending over less than an entire length of the at least one of the side faces and comprising a portion of the light exit face, a portion of the surface opposite the light exit face, and first and second lateral surfaces connecting said portions of the light exit face and the surface opposite the light exit face;

wherein the first lateral surface is covered by a reflector and the second lateral surface is not covered by a reflector and is arranged at an acute angle relative to a principal direction of extent of the light waveguide to form a light entry face; and

wherein the light source is positioned in front of the light entry face.

2. The light source element according to claim 1 wherein light radiation emitted during operation by the light source penetrates into the light waveguide at an oblique angle.

3. The light source element according to claim 1 wherein the first and second lateral surfaces intersect so that the at least one projection has a triangular cross-sectional shape.

4. The light source element according to claim 1 wherein the reflectors are integrally connected to one another.

5. The light source element according to claim 1 wherein a material of the reflectors is capable of being injection molded and the reflectors are manufactured by injection molding.

6. The light source element according to claim 1 wherein a material of the reflectors is formed of a thermoplastic polyester on a base of polybutylene terephthalate.

7. The light source element according to claim 1 wherein a material of the reflectors comprises Pocan®

.

8. The light source element according to claim 1 wherein reflectors are formed of one of a reflective and a diffusely back-scattering film.

9. The light source element according to claim 8 wherein the film is formed on a base of polycarbonate.

10. The light source element according to claim 8 wherein at least one opening is formed in the film for passage of light radiation.

11. The light source element according to claim 8 wherein the film is at least one of coated and printed with white color.

12. The light source element according to claim 1 wherein the light source element forms a closed ring.

13. The light source element of claim 1, wherein at least one of the light exit face and the surface lying opposite the light exit face comprise light-scattering sections, the light scattering sections comprising small elevations applied to the surface of the waveguide as a point matrix.

14. The light source element of claim 1, wherein the surface lying opposite the light exit face and all of the lateral surfaces except for the second lateral surface are covered with reflectors that contact the surfaces and at least one of reflect and diffusely return light.

15. The light source element of claim 1, wherein at least one of the light exit face and the surface lying opposite the light exit face comprise light-scattering sections and plane sections, and an area ratio of the plane sections to the light-scattering sections along the light waveguide is set such that a uniform luminance of the light source element is achieved.

16. The light source element of claim 1, wherein the light exit face and the surface lying opposite the light exit face are substantially parallel.

17. The light source element of claim 1, wherein the at least one projection comprises two or more projections each extending over less than an entire length of the at least one of the side faces.

18. The light source element of claim 17, wherein each of the two or more projections comprises a separate light entry face.

19. The light source element of claim 17, wherein at least one of the two or more projections is positioned on a first side of a midpoint of the light waveguide, and at least one of the two or more projections is positioned on a second side of the midpoint opposite the first side.

20. The light source element of claim 19, wherein at least two projections are formed in each of the side faces of the light waveguide, and for each side face of the waveguide, at least one of the at least two projections is positioned on a first side of a midpoint of the light waveguide, and at least one of the at least two projections is positioned on a second side of the midpoint opposite the first side.

21. A liquid crystal display, comprising:

a light source element comprising a light waveguide and a light source, the light waveguide having a light exit face and a surface lying opposite the light exit face, the light exit face and the surface lying opposite the light exit face being connected by side faces; and

a liquid crystal element arranged at a side of the light exit face of the light source element,

wherein the surface lying opposite the light exit face and at least some portions of the side faces are covered and contacted with reflectors that at least one of reflect and diffusely return light;

wherein at least one projection is formed in at least one of the side faces of the light waveguide, each projection extending over less than an entire length of the at least one of the side faces and comprising a portion of the light exit face, a portion of the surface opposite the light exit face, and first and second lateral surfaces connecting said portions of the light exit face and the surface opposite the light exit face;

wherein the first lateral surface is covered by a reflector and the second lateral surface is not covered by a reflector and is arranged at an acute angle relative to a principal direction of extent of the light waveguide to form a light entry face; and

wherein the light source is positioned in front of the light entry face.

22. The liquid crystal display according to claim 21 wherein the liquid crystal element is held spaced from the light exit face by spacers.

23. The liquid crystal display of claim 21, wherein at least one of the light exit face and the surface opposite the light exit face comprises light-scattering sections and plane sections, and an area ratio of the plane sections to the light-scattering sections along the light waveguide is set such that a uniform luminance of the light source element is achieved.

24. The liquid crystal display of claim 21, further comprising a plurality of light sources, wherein the plurality of light sources are coplanar and are positioned in a plane parallel to the surface opposite the light exit surface.

25. The light source element of claim 21, wherein the at least one projection comprises two or more projections each extending over less than an entire length of the at least one of the side faces.

26. The light source element of claim 25, wherein each of the two or more projections comprises a separate light entry face.

27. The light source element of claim 25, wherein at least one of the two or more projections is positioned on a first side of a midpoint of the light waveguide, and at least one of the two or more projections is positioned on a second side of the midpoint opposite the first side.

28. The light source element of claim 27, wherein at least two projections are formed in each of the side faces of the light waveguide, and for each side face of the waveguide, at least one of the at least two projections is positioned on a first side of a midpoint of the light waveguide, and at least one of the at least two projections is positioned on a second side of the midpoint opposite the first side.

29. A light source element, comprising:

a light waveguide and a light source, the light waveguide having a light exit face and a surface lying opposite the light exit face, the light exit face and the surface lying opposite the light exit face being connected by side faces,

wherein the surface lying opposite the light exit face and at least some portions of the side faces are covered and contacted with reflectors that at least one of reflect and diffusely return light;

wherein at least one projection is formed in at least one of the side faces of the light waveguide and the surface opposite the light exit face, each projection comprising portions of first and second lateral surfaces connecting the light exit face and the surface opposite the light exit face;

wherein the at least one projection comprises a light entry face in front of which the light source is positioned, the light entry face being arranged at an acute angle relative to a principal direction of extent of the light waveguide; and

wherein the light exit face and the surface opposite the light exit face are substantially parallel.

30. The light source element of claim 29, further comprising a plurality of light sources, wherein the plurality of light sources are coplanar and are positioned in a plane parallel to the surface opposite the light exit surface.

31. The light source element of claim 29, wherein the at least one projection comprises two or more projections each extending over less than an entire length of the at least one of the side faces or the surface opposite the light exit face.

32. The light source element of claim 31, wherein each of the two or more projections comprises a separate light entry face.

33. The light source element of claim 31, wherein at least one of the two or more projections is positioned on a first side of a midpoint of the light waveguide, and at least one of the two or more projections is positioned on a second side of the midpoint opposite the first side.