Light source

• US 20040264185A1
• Filed: 04/28/2004
• Published: 12/30/2004
• Est. Priority Date: 04/29/2003
• Status: Active Grant

• Current Assignee: OSRAM OLED GMBH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Bogner, Georg, Grotsch, Stefan
• Granted Patent: US 7,467,885 B2
• Time in Patent Office: Days
• US Class Current: 362/231
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

A light source, such as for a projection system, having a plurality of semiconductor chips and at least two different, electromagnetic-radiation-emitting chip types with different emission spectra, each semiconductor chip having a chip coupling-out area through which radiation is coupled out. Furthermore, the light source has a plurality of primary optical elements, each semiconductor chip being assigned a primary optical element, which in each case has a light input and a light output and reduces the divergence of at least part of the radiation emitted by the semiconductor chip during the operation thereof. The semiconductor chips with the primary optical elements are arranged in at least two groups that are spatially separate from one another, with the result that the groups emit separate light cones during operation of the semiconductor chips. The separate light cones of the groups are superposed by means of a secondary optical arrangement to form a common light cone.

Claims

1. Light source comprising:

a plurality of semiconductor chips and at least two different electromagnetic-radiation-emitting chip types having different emission spectra, each of said semiconductor chips having a chip coupling-out area through which the electromagnetic radiation is coupled out,

a plurality of primary optical elements, each of said semiconductor chips having a respective one of said primary optical elements corresponding thereto, which has a light input and a light output and reduces the divergence of at least part of the electromagnetic radiation emitted by the semiconductor chip during operation thereof,

wherein the semiconductor chips with the respectively corresponding primary optical elements are arranged in at least two groups that are spatially separate from one another, such that the groups emit separate light cones during operation of the semiconductor chips, and

a secondary optical arrangement, wherein the separate light cones of the groups are superposed by means of said secondary optical arrangement to form a common light cone.

2. Light source according to claim 1,

wherein

the separate light cones of the groups are superposed by means of the secondary optical arrangement to form a common light cone with a common colour locus.

3. Light source according to claim 2,

wherein

the colour locus of the common light cone lies in the white region of the CIE chromaticity diagram.

4. Light source according to claim 1,

wherein

at least one of the groups has semiconductor chips of only one chip type.

5. Light source according to claim 1,

wherein

the semiconductor chips of a chip type are contained only in one of the groups.

6. Light source according to claim 1,

wherein

the plurality of semiconductor chips has a first, a second and a third chip type, the emission spectra of which are such that white light can be generated by superposition of the radiation emitted by semiconductor chips of different chip types.

7. Light source according to claim 6,

wherein

the first chip type emits green radiation, the second chip type emits red radiation and the third chip type emits blue radiation.

8. Light source according to claim 6,

wherein

the semiconductor chips of the first chip type are arranged in a first group and the semiconductor chips of the second and third chip types are arranged in a second group, the semiconductor chips of different chip types of the second group being arranged in a manner intermixed with one another.

9. Light source according to claim 1,

wherein

the semiconductor chips of a same chip type are arranged in a group of their own.

10. Light source according to claim 1,

wherein

the secondary optical arrangement has at least one selectively reflective unit, which is transmissive to the radiation of at least one of the separate light cones and is reflective to the radiation of another of the separate light cones and by means of which at least two separate light cones are superposed.

11. Light source according to claim 10,

wherein

the selectively reflective unit contains a dichroic layer system.

12. Light source according to claim 10,

wherein

the secondary optical arrangement has at least one combining cube based on at least one selectively reflective unit.

13. Light source according to claim 1,

wherein

an aperture angle of the separate light cones is between 0 and 60°

.

14. Light source according to claim 1,

wherein

the primary optical elements of at least one group are at least partly arranged in such a way that their light outputs are densely packed.

15. Light source according to claim 1,

wherein

the semiconductor chips with the primary optical elements are essentially arranged in a common plane.

16. Light source according to claim 1,

wherein

the semiconductor chips with the primary optical elements are arranged in matrix-like fashion at least partly or in partial groups.

17. Light source according to claim 1,

wherein

the light input has a light input area or a light input opening, the size of which is less than or equal to two times the chip coupling-out area.

18. Light source according to claim 1,

wherein

the primary optical element is in each case an optical concentrator, the light input being the actual concentrator output, so that light passes through the concentrator in the opposite direction compared with the customary application of a concentrator for focusing and is thus not concentrated, but rather leaves the concentrator with reduced divergence through the light output.

19. Light source according to claim 18,

wherein

the optical concentrator is a CPC-, CEC- or CHC-like concentrator.

20. Light source according to claim 18,

wherein

the concentrator has side walls which connect the light input to the light output and are formed in such a way that direct connecting lines running on the side walls essentially run straight between the light input and the light output.

21. Light source according to claim 18,

wherein

the concentrator has a cross-sectional area in the form of a regular polygon in a region on the side of the light input, and in that it likewise has a cross-sectional area in the form of a regular polygon in a region on the side of the light output.

22. Light source according to claim 18,

wherein

the concentrator has a basic body defining a cavity, the inner wall of which basic body is reflective to a light emitted by the semiconductor chip, and/or the inner wall of which basic body is essentially provided with a layer or layer sequence, which is reflective to a light emitted by the semiconductor chip.

23. Light source according to claim 18,

wherein

the concentrator is a dielectric concentrator, the basic body of which is a solid body composed of a dielectric material with a suitable refractive index, so that light coupled in via the light input is reflected in it by total reflection at the lateral interface, coupling the light input to the light output, of the solid body to the surrounding medium.

24. Light source according to claim 23,

wherein

the light output is surface of the solid body which is curved in lens-like fashion.

25. Light source according to claim 24,

wherein

the light output is curved like an aspherical lens.

26. Light source according to claim 23,

wherein

the dielectric concentrator is at least partly provided with a layer or layer sequence, which is reflective to light emitted by the respective semiconductor chip.

27. Light source according to claim 18,

wherein

the concentrator is arranged downstream of the semiconductor chip in the main radiating direction thereof, and in that there is a gap between the chip coupling-out area and the light input of the concentrator.

28. Light source according to claim 27,

wherein

the gap is substantially free of solid or viscous material.

29. Light source according to claim 27,

wherein

each semiconductor chip is assigned one or more reflector elements, which are arranged and/or are of a form such that some of the light beams which do not pass directly from the semiconductor chip into the concentrator are multiply reflected at said reflector elements and directed onto the light input of the concentrator at a smaller angle with respect to the main radiating direction of the semiconductor chip.

30. Light source according to claim 23,

wherein

the basic body of the concentrator comprises a transparent glass, a transparent crystal or a transparent plastic, that is produced in a transfer moulding method.

31. Light source according to claim 1,

wherein

the semiconductor chip is an electromagnetic-radiation-emitting diode.

32. Light source according to claim 1,

wherein

the semiconductor chips are arranged on a respective carrier on which they are in each case surrounded by a frame at or in which the primary optical element is fitted and by which the latter is held and/or by which the latter is adjusted relative to the chip coupling-out area.

33. Light source according to claim 32,

wherein

at least some of the carriers and/or in each case the carrier and the frame are formed in one part with one another.

34. Light source according to claim 32,

wherein

the inner area of the frame and/or free areas of that surface of the carrier which faces toward the radiating direction of the semiconductor chip

is or are reflective to light emitted by the respective semiconductor chip and/or

is or are at least partly provided with a layer or layer sequence which is reflective to light emitted by the respective semiconductor chip.

35. Light source according to claim 1,

wherein

a plurality of primary optical elements are formed in one part with one another.

36. Light source according to claim 1, comprising three different electromagnetic-radiation-emitting chip types having different emission spectra.

37. Light source according to claim 1,

wherein

the primary optical elements of at least one group are at least partly arranged in such a way that their light outputs adjoin one another without any gaps.

38. Light source according to claim 1,

wherein

the light input has a light input area or a light input opening, the size of which is less than or equal to 1.5 times the chip coupling-out area.

39. Light source according to claim 21,

wherein

said concentrator has a cross-sectional area in the form of a square cross-sectional area in a region on the side of the light input.

40. Light source according to claim 21,

wherein

said concentrator has a cross-sectional area in the form of one of the group of a triangular, quadrangular, hexagonal and octagonal cross-sectional area, in a region on the side of the light output.

41. Light source according to claim 22,

wherein

said layer or layer sequence on the inner wall of said basic body is a metallic layer, which is reflective to a light emitted by the semiconductor chip.

42. Light source according to claim 26,

wherein

said layer or layer sequence of the dielectric concentrator is a metallic layer, which is reflective to light emitted by the respective semiconductor chip.

43. Light source according to claim 23,

wherein

the basic body of the concentrator comprises a transparent glass, a transparent crystal or a transparent plastic, that is produced in an injection moulding method.

44. Light source according to claim 1,

wherein

the semiconductor chip is an electromagnetic-radiation-emitting diode with a radiating characteristic which complies at least approximately with Lambert'"'"'s law.

45. Light source according to claim 1,

wherein

the semiconductor chip is a thin-film light-emitting diode.

46. Light source according to claim 1,

wherein

an aperture angle of the separate light cones is between 0 and 40°

, the limits being included.

47. Light source according to claim 1,

wherein

an aperture angle of the separate light cones is between 0 and 20°

, the limits being included.

48. Light source according to claim 34,

wherein

said layer or layer sequence at least partly provided on the inner area of the frame and/or free areas of that surface of the carrier which faces toward the radiating direction of the semiconductor chip is a metallic layer.