Combined light source for projection display

• US 7,090,357 B2
• Filed: 12/23/2003
• Issued: 08/15/2006
• Est. Priority Date: 12/23/2003
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Magarill, Simon, Ardashnikov, Boris, English, R. Edward Jr.
• Primary Examiner(s): Dowling, William C.
• Application Number:
  US10/745,000
• Publication Number:
  US 20050134811A1
• Time in Patent Office: 966 Days
• Field of Search: 353/31, 353/33, 353/34, 353/37, 353/98, 353/99, 353/81, 349/5, 349/6, 349/7, 349/8, 349/9, 362/555, 362/559, 362/84, 362/227, 362/230, 362/231, 362/234, 362/236, 362/253, 359/639, 359/640
• US Class Current: 353/94
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• 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

High pressure mercury arc lamps are commonly used as the illumination source in many projection systems. Such lamps may be deficient in either output power or spectrum, and so it is desirable to combine the light from the lamp with light from a second light generator. The second light generator may be another mercury lamp or a solid state source, such as one or more light emitting diodes. Different ways of combining light from two light generators are described. The second light source may be an arrangement of a number of red LEDs that supplements the red light produced by the mercury light. A tunnel integrator may be used to homogenize the combined light beam and to reduce the angular separation between the light beams from the two light generators.

Claims

1. A projector system, comprising:

a light source comprising

a first light generator producing first light and a first reflector disposed to collect at least part of the first light and to direct the collected first light in a first direction,

a second light generator producing second light and a second reflector disposed to collect at least part of the second light and to direct the collected second light in a second direction, and

a light combiner that combines the first light and the second light to produce a combined light beam;

at least one image display unit illuminated by at least a part of the combined light beam, the at least one image display unit imposing an image on the at least a part of the combined light beam to form an image beam; and

a light homogenizer unit between the light source and the at least one image display unit to homogenize the combined light beam;

wherein the first light enters the homogenizer unit with a first angular distribution and the second light enters the homogenizer unit with a second angular distribution substantially non-overlapping with the first angular distribution.

2. A system as recited in claim 1, further comprising a projector lens unit that projects the image beam.

3. A system as recited in claim 1, further comprising at least one polarizing beamsplitter, the combined light beam being incident on the at least one image display unit via the polarizing beamsplitter, the at least one image display unit being a reflective image display unit and producing a reflected image beam, the reflected image beam being separated from the combined light beam by the polarizing beamsplitter.

4. A system as recited in claim 1, wherein the homogenizer unit is a tunnel integrator.

5. A system as recited in claim 4, wherein the tunnel integrator comprises the light combiner, the first and second light generators directing the first and second lights respectively into the tunnel integrator and the combined beam emerging from the tunnel integrator.

6. A system as recited in claim 4, further comprising an image relay system to relay an image of an output of the homogenizer unit to the at least one image display unit.

7. A system as recited in claim 4, wherein the tunnel integrator has an entrance aperture and an exit aperture, the entrance aperture having a size different from a size of the exit aperture.

8. A system as recited in claim 7, wherein the tunnel integrator is a trapezoidal tunnel integrator.

9. A system as recited in claim 1, wherein the first light enters an entrance aperture of the homogenizer unit at a first aperture portion and the second light enters the entrance aperture at a second aperture portion different from the first aperture portion.

10. A system as recited in unit as recited in claim 1, wherein the at least one image display unit comprises at least two image display units and further comprising a color separator disposed to separate the combined beam into at least two beams of different color bands to illuminate the at least two image display units with respectively light of different color bands.

11. A system as recited in unit as recited in claim 10, wherein the color separator receives image light in the different color bands from the at least two image display units and combines the image light in the different color bands into the image beam that is projected by the projector lens unit.

12. A system as recited in unit as recited in claim 1, further comprising a controller coupled to the at least one image display unit to control an image produced by the at least one image display unit.

13. A light source unit for a projection system, comprising:

a first light generator producing first light and a first reflector disposed to collect at least part of the first light and to direct the collected first light in a first direction;

a second light generator producing second light and a second reflector disposed to collect at least part of the second light and to direct the collected second light in a second direction;

a light combiner that combines the first light and the second light to produce a combined light beam, the light combiner comprising a prism pair formed from first and second prisms, the first light being substantially totally internally reflected within the first prism and the second light being substantially transmitted through the first and second prisms to form a combined light beam; and

an integrator, the combined, light beam entering the integrator at an entrance aperture of the integrator.

14. A unit as recited in claim 13, wherein the second light generator comprises at least one light emitting diode (LED).

15. A unit as recited in claim 14, wherein the second reflector comprises a reflecting surface conforming to a surface of revolution about a revolution axis, the at least one LED unit having an LED axis non-parallel to the revolution axis.

16. A unit as recited in claim 13, wherein the first light generator comprises a high pressure mercury lamp.

17. A unit as recited in claim 16, wherein the second light generator comprises a high pressure mercury lamp.

18. A unit as recited in claim 13, further comprising an index matching layer disposed between the first and second prisms, the second light substantially transmitted through the first and second prisms passing through the index-matching layer.

19. A unit as recited in claim 18, wherein the index-matching layer is an adhesive layer.

20. A unit as recited in claim 18, wherein the first light totally internally reflects within the first prism at a surface area substantially free of the refractive index-matching layer.

21. A unit as recited in claim 13, wherein the integrator is a tunnel integrator.

22. A unit as recited in claim 21, wherein the tunnel integrator is a tapered integrator.

23. A light source unit for a projection system, comprising:

a first light generator unit producing a first light beam having a first cone angle, light in the first light beam having a relatively broad spectrum;

a second light generator unit producing a second light beam separated from the first light beam, the second light beam having a second cone angle substantially equal to the first cone angle, light in the second light beam having a relatively narrow spectrum; and

a light integrator disposed to receive both the first and second light beams and to produce a combined output beam.

24. A unit as recited in claim 23, wherein the first light generator unit comprises a mercury discharge lamp.

25. A unit as recited in claim 23, wherein the second light generator unit comprises at least one light emitting diode (LED) unit.

26. A unit as recited in claim 25, wherein light from the at least one LED unit is reflected as the second light beam by a reflector, the reflector having at least one reflecting surface conforming to a surface of revolution about a revolution axis non-parallel to an LED axis of the at least one LED unit.

27. A unit as recited in claim 23, further comprising a first reflecting surface disposed proximate an entrance aperture of the light integrator, one of the first and second light beams being directed into the entrance aperture via reflection at the first reflecting surface.

28. A unit as recited in claim 23, wherein the first light beam enters the light integrator with a first angular distribution and the second light beam enters the light integrator unit with a second angular distribution substantially non-overlapping with the first angular distribution.

29. A unit as recited in claim 23, wherein the first light beam enters an entrance aperture of the light integrator at a first aperture portion and the second light beam enters the entrance aperture at a second aperture portion different from the first aperture portion.

30. A unit as recited in claim 27, further comprising a prism pair comprising first and second prisms, the first prism having a totally internally reflecting surface that comprises the reflecting surface, light in the other of the first and second light beams being transmitted through both the first and second prisms.

31. A unit as recited in claim 27, wherein, light in the other of the first and second light beams enters the entrance aperture without passing through the reflecting surface.

32. A unit ac recited in claim 31, wherein the reflecting surface comprises a first mirror.

33. A unit as recited in claim 31, further comprising a second reflecting surface disposed proximate the entrance aperture, light in the one of the other of the first and second light beams and a third light beam being reflected off the second reflecting surface into the entrance aperture.

34. A unit as recited in claim 23, wherein the integrator is a tunnel integrator.

35. A unit as recited in claim 34, wherein the tunnel integrator is a tapered tunnel integrator.

36. A unit as recited in claim 23, further comprising an imager unit disposed to receive the combined output beam, and to produce an image beam, and a projection lens unit disposed to project the image beam.

37. A unit as recited in claim 36, wherein the imager unit includes at least one reflective image display unit and at least one respective polarizing beamsplitter, at least pan of the combined output beam passing to the at least one reflective image display unit via the at least one respective polarizing beamsplitter, image light from the at least one reflective image display unit being separated from the at least part of the combined output beam by the at least one respective polarizing beamsplitter.

38. A unit as recited in claim 37, wherein the at least one reflective image display unit comprises first, second and third reflective image display units, and the imager unit includes a color separation unit disposed to separate the combined output beam into first, second and third color bands directed respectively to the first, second and third reflective image display units.

39. A unit as recited in claim 36, further comprising a controller coupled to at least one image display device in the image unit, to control an image produced by the at least one image display device.