Remote wavelength conversion in an illumination device

• US 20050270775A1
• Filed: 06/04/2004
• Published: 12/08/2005
• Est. Priority Date: 06/04/2004
• Status: Active Grant

• Current Assignee: Signify North America Corporation (Signify N.V.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Harbers, Gerard, Keuper, Matthijs H.
• Granted Patent: US 7,070,300 B2
• Time in Patent Office: Days
• US Class Current: 362/231
• CPC Class Codes: G02B 27/1046 for use with transmissive spatial light modulators
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: G03B 21/204 using secondary light emission, e.g. luminescence or fluorescence using different colours G03B33/00; if related to video signals H04N9/3197
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

An illumination device uses a wavelength converting element, such as a phosphor layer, that is physically separated from a light source, such as one or more light emitting diodes, a Xenon lamp or a Mercury lamp. The wavelength converting element is optically separated from the light source, so that the converted light emitted by the wavelength converting element is prevented from being incident on the light source. Accordingly, the temperature limitations of the wavelength converting element are removed, thereby permitting the light source to be driven with an increased current to produce a higher radiance. Moreover, by optically separating the wavelength converting element from the light source, the conversion and recycling efficiency of the device is improved, which also increases radiance.

Claims

1. An illumination device comprising:

a light source that emits light having a first wavelength range along a first beam path;

a wavelength converting element in the first beam path, the wavelength converting element being physically separated from the light source, the wavelength converting element converting the light having a first wavelength range into light having a second wavelength range along a second beam path; and

a color separation element disposed between the light source and the wavelength converting element, the color separation element being configured to prevent substantially all of the light having the second wavelength range from being incident on the light source.

2. The illumination device of claim 1, wherein the light source is one of a semiconductor light emitting device, a Xenon lamp, and a Mercury lamp.

3. The illumination device of claim 1, wherein the light source comprises one or more light emitting diodes.

4. The illumination device of claim 1, further comprising at least one of a radiance enhancement film and a polarization recovery component coupled to receive the light emitted from the wavelength converting element.

5. The illumination device of claim 4, wherein the radiance enhancement film comprises at least one of a diffractive optical element and a micro refractive element and wherein the polarization recovery component comprises a non-absorbing polarizer.

6. The illumination device of claim 1, wherein the wavelength converting element is a phosphor.

7. The illumination device of claim 6, wherein the phosphor is patterned.

8. The illumination device of claim 6, wherein the wavelength converting element comprises a rotatable element, the rotatable element having at least a first section being covered with a first phosphor that converts the light having a first wavelength range to the light having the second wavelength range and a second section being covered with a second phosphor that converts the light having a first wavelength range to the light having a third wavelength range, wherein the color separation element is configured to further prevent substantially all of the light having the third wavelength range from being incident on the light source.

9. The illumination device of claim 1, wherein the color separation element is selected from the group consisting of a dichroic mirror, a dichroic cube, a dichroic sphere, a diffractive optical element and a hologram.

10. The illumination device of claim 1, wherein the wavelength converting element is mounted on a reflective submount.

11. The illumination device of claim 1, further comprising a lens, wherein the color separation element reflects the light having a first wavelength range from the light source to the wavelength converting element and transmits the light having the second wavelength range from the wavelength converting element to the lens.

12. The illumination device of claim 1, further comprising:

a first optical element disposed between the light source and the color separation element, the first optical element collimates the light emitted from the light source; and

a second optical element disposed between the wavelength converting element and the color separation element, the second optical element focuses the collimated light from the light source on the wavelength converting element and collimates the converted light having a second wavelength range.

13. The illumination device of claim 12, wherein the first optical element and the second optical element each include at least one of a collimator, reflective compound parabolic concentrator element, total internal reflecting optical element, a rectangular reflective angle transformer, a condenser lens, and a lens assembly.

14. The illumination device of claim 12, further comprising:

a second light source that emits light having a third wavelength range along a third beam path;

wherein the color separation element is a first color separation element that is further disposed between the second light source and the wavelength converting element, the first color separation element configured to transmit substantially all of the light having the second wavelength range and the light having the third wavelength range and to reflect substantially all of the light having a first wavelength range; and

a second color separation element disposed between the second light source and the first color separation element, the second color separation element being configured to transmit substantially all of the light having the second wavelength range and to reflect substantially all of the light having the third wavelength range;

wherein the wavelength converting element is in the first beam path and the third beam path, the wavelength converting element converting both the light having the first wavelength range and the light having the third wavelength range into light having the second wavelength range.

15. The illumination device of claim 14, further comprising:

a third optical element disposed between the second light source and the second color separation element, the third optical element collimates the light emitted from the second light source.

16. The illumination device of claim 12, further comprising:

a second light source that emits light having a third wavelength range along a third beam path;

a second wavelength converting element in the third beam path, the second wavelength converting element being physically separated from the second light source, the second wavelength converting element converting the light having the third wavelength range to light having a fourth wavelength range along a fourth beam path; and

a second color separation element disposed between the second light source and the second wavelength converting element, the second color separation element being configured to prevent substantially all of the light having the fourth wavelength range from the second wavelength converting element from being incident on the second light source; and

a third color separation element disposed between the wavelength converting element and the second wavelength converting element, the third color separation element being configured to combine the light having the second wavelength range and the light having the fourth wavelength range.

17. The illumination device of claim 16, further comprising a lens disposed after the third color separation element.

18. The illumination device of claim 16, wherein the third color separation element is one of an X-plate and an X-cube.

19. The illumination device of claim 16, wherein the lens is a condenser lens.

20. The illumination device of claim 16, further comprising a third light source that emits a light having a fifth wavelength range, wherein the third color separation element is further configured to combine the light having the second wavelength range, the light having the fourth wavelength range, and the light having the fifth wavelength range.

21. The illumination device of claim 20, further comprising:

a first of at least one of a radiance enhancement film and a polarization recovery component disposed between the color separation element and the third color separation element;

a second of at least one of a radiance enhancement film and a polarization recovery component disposed between the second color separation element and the third color separation element; and

a third of at least one of a radiance enhancement film and a polarization recovery component disposed between the third light source and the third color separation element.

22. The illumination device of claim 21, further comprising:

a first microdisplay disposed between the first of at least one of a radiance enhancement film and a polarization recovery component and the third color separation element;

a second microdisplay disposed between the second of at least one of a radiance enhancement film and a polarization recovery component and the third color separation element; and

a third microdisplay disposed between the third of at least one of a radiance enhancement film and a polarization recovery component and the third color separation element;

wherein the lens is a projector lens.

23. The illumination device of claim 16, further comprising:

a third light source that emits light having a fifth wavelength range along a fifth beam path;

a third wavelength converting element in the fifth beam path, the third wavelength converting element being physically separated from the third light source, the third wavelength converting element converting the light having the fifth wavelength range to light having a sixth wavelength range along a sixth beam path; and

a fourth color separation element disposed between the third light source and the third wavelength converting element, the fourth color separation element being configured to prevent substantially all of the light having the sixth wavelength range from the third wavelength converting element from being incident on the third light source;

wherein the third color separation element is further configured to combine the light having the second wavelength range, the light having the fourth wavelength range, and the light having the sixth wavelength range.

24. The illumination device of claim 23, wherein the second wavelength range, fourth wavelength range and sixth wavelength range are in the red, green and blue spectra, respectively.

25. The illumination device of claim 1, wherein the color separation element transmits the light having a first wavelength range from the light source to the wavelength converting element and reflects the light having the second wavelength range from the wavelength converting element back to the wavelength converting element.

26. The illumination device of claim 25, the device further comprising:

a first optical element disposed between the light source and the color separation element, the first optical element collimates the light emitted from the light source;

a second optical element disposed between the wavelength converting element and the color separation element, the second optical element focuses the collimated light from the light source on the wavelength converting element, wherein the color separation element is disposed between the first optical element and the second optical element; and

a third optical element, wherein the wavelength converting element is disposed between the second optical element and the third optical element, the wavelength converting element emits light having the second wavelength range along the second beam path and along a third beam path that is in the opposite direction of the second beam path, the third optical element collimates the light having the second wavelength range along the third beam path and the second optical element collimates the light having the second wavelength range along the second beam path.

27. The illumination device of claim 26, wherein the first optical element, the second optical element, and the third optical element each include at least one of a collimator, reflective compound parabolic concentrator element, total internal reflecting optical element, a rectangular reflective angle transformer, a condenser lens, and a lens assembly.

28. The illumination device of claim 26, further comprising a second color separation element, the wavelength converting element being disposed between the second color separation element and second optical element, the second color separation element transmits light having the second wavelength range and reflects light having the first wavelength range back to the wavelength converting element.

29. The illumination device of claim 26, further comprising

a second light source that emits light having a third wavelength range along a third beam path;

a second color separation element disposed between the second light source and the wavelength converting element, the second color separation element being configured to transmit substantially all of the light having the second wavelength range and to reflect substantially all of the light having the third wavelength range;

a fourth optical element disposed between the second light source and the second color separation element, the fourth optical element collimates the light emitted from the second light source;

wherein the wavelength converting element is in the first beam path and the third beam path, the third optical element focuses the collimated light from the second light source onto the wavelength converting element, the wavelength converting element converts both the light having the first wavelength range and the light having the third wavelength range into light having the second wavelength range.

30. The illumination device of claim 26, wherein the first wavelength range and the third wavelength range are approximately the same wavelength range.

31. The illumination device of claim 1, further comprising a second color separation element disposed over the wavelength converting element, the second color separation element configured to transmit light having the first wavelength range over a first range of angles and to transmit light having the second wavelength range over a second range of angles, the second range of angles is smaller than the first range of angles, wherein the second color separation element reflects light having the second wavelength range outside the second range of angles back to the wavelength converting element.

32. The illumination device of claim 31, wherein the second range of angles is approximately 30 degrees.

33. The illumination device of claim 31, wherein the second color separation element is a dichroic mirror.

34. The illumination device of claim 31, wherein the second color separation element is disposed in the beam path between the light source and the wavelength converting element.

35. The illumination device of claim 31, wherein the wavelength converting element is disposed in the beam path between the light source and the second color separation element, the illumination device further comprising a third color separation element that transmits light having the second wavelength range and reflecting light having the first wavelength range, the second color separation element being disposed between the third color separation element and the wavelength converting element.

36. The illumination device of claim 1, further comprising a second color separation element disposed over the wavelength converting element, the second color separation element configured to transmit light having the second wavelength range over a range of angles, wherein the second color separation element reflects light having the second wavelength range outside the range of angles back to the wavelength converting element.

37. The illumination device of claim 36, wherein the wavelength converting element comprises a plurality of phosphor dots, the illumination device further comprising an LCD panel wherein the second color separation element is disposed between the wavelength converting element and the LCD panel.

38. The illumination device of claim 37, further comprising:

an optical element disposed between the light source and the wavelength converting element, the optical element collimates the light emitted from the light source; and

a lens, the LCD panel being disposed between the second color separation element and the lens.

39. The illumination device of claim 1, wherein the wavelength converting element is physically separated from the light source by more than one millimeter.

40. The illumination device of claim 1, wherein the wavelength converting element is physically separated from the light source by one of air, gas, and vacuum.

41. The illumination device of claim 1, wherein the wavelength converting element is physically separated from the light source sufficiently to prevent substantial conductive heating of the wavelength converting element by the light source.

42. A device comprising:

a light source that emits light having a first wavelength range;

a first optical element associated with the light source, the first optical element collimates the light emitted from the light source along a first beam path;

a color separation element in the first beam path, the color separation element configured to direct substantially all of the collimated light along the first beam path toward a second optical element, the second optical element focuses the collimated light; and

a wavelength converting element receiving the focused light from the second optical element, the wavelength converting element configured to at least partially absorb light of the first wavelength range and to emit light having a second wavelength range, the second optical element collimates the light having the second wavelength range emitted by the wavelength converting element, wherein the color separation element prevents light having a second wavelength range from being incident on the light source.

43. The illumination device of claim 42, wherein the light source is one of a semiconductor light emitting device, a Xenon lamp, and a Mercury lamp.

44. The illumination device of claim 42, wherein the light source comprises one or more light emitting diodes.

45. The device of claim 42, wherein the color separation element reflects light having a first wavelength range and transmits light having a second wavelength range.

46. The device of claim 45, wherein the wavelength converting element is mounted on a reflective substrate.

47. The device of claim 46, wherein the reflective substrate is mounted on a heatsink.

48. The device of claim 42, wherein the color separation element transmits light having a first wavelength range and reflects light having a second wavelength range.

49. The device of claim 48, further comprising a third optical element, the wavelength converting element being disposed between the second optical element and the third optical element, the third optical element collimates light having a second wavelength range emitted by the wavelength converting element.

50. The device of claim 49, further comprising a second color separation element, the third optical element being disposed between the second color separation element and the wavelength converting element, the second color separation element transmits light having the second wavelength range and reflects light having the first wavelength range.

51. A device comprising:

a light source that emits light having a first wavelength range;

a first color separation element that receives light emitted by the light source, the first color separation element is configured to direct substantially all of the light emitted by the light source toward a wavelength covering element;

the wavelength converting element receives the light from the first color separation element, the wavelength converting element is configured to at least partially absorb light of the first wavelength range and to emit light having a second wavelength range, wherein the first color separation element prevents light having a second wavelength range from being incident on the light source; and

a second color separation element that receives light emitted by the wavelength converting element, the second color separation element is configured reflect light in the first wavelength range back to the wavelength converting element and to transmit light in the second wavelength range that is incident on the second color separation element in a first range of angles and to reflect light in the second wavelength range that is incident on the second color separation element outside the first range of angles.

52. The illumination device of claim 51, wherein the light source is one of a semiconductor light emitting device, a Xenon lamp, and a Mercury lamp.

53. The illumination device of claim 51, wherein the light source comprises one or more light emitting diodes.

54. The device of claim 51, further comprising a polarization recovery component, wherein the wavelength converting element is disposed between the polarization recover component and the light source.

55. The device of claim 51, wherein the light emitted by the light source having a first wavelength range is reflected by the first color separation element and light emitted by the wavelength converting element having a second wavelength range is transmitted through the first color separation element before being incident on the second color separation element.

56. The device of claim 51, further comprising:

a first optical element disposed between the light source and the first color separation element, the first optical element collimates the light emitted from the light source; and

a second optical element disposed between the first color separation element and the wavelength converting element, the second optical element focuses the light from the first color separation element towards the wavelength converting element.

57. The device of claim 56, further comprising a third optical element disposed between the wavelength converting element and the second color separation element, the third optical element collimates the light emitted by the wavelength converting element.

58. The device of claim 57, wherein the light emitted by the light source having a first wavelength range is transmitted through the first color separation element and light emitted by the wavelength converting element having a second wavelength range is reflected by the first color separation element.

59. The device of claim 51, wherein the wavelength converting element is physically separated from the light source by one of air, gas, and vacuum.