Combined light source for projection display

• US 7,261,423 B2
• Filed: 08/11/2006
• Issued: 08/28/2007
• 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, English, R. Edward Jr., Ardashnikov, Boris
• Primary Examiner(s): Dowling; William C.
• Application Number:
  US11/464,052
• Publication Number:
  US 20060274277A1
• Time in Patent Office: 382 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/94, 353/98, 353/99, 349/5, 349/6, 349/7, 349/8, 349/9, 362/84, 362/555, 362/559, 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;

a second light generator producing second light; 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 modulating at least a part of the combined light beam with image information; and

a light homogenizer unit between the light source and the at least one image display unit to homogenize the combined light beam, the first light entering the homogenizer unit with a first angular distribution and the second light entering 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 first light generator comprises a lamp to generate the first light.

5. A system as recited in claim 1, wherein at least the first light generator comprises one or more light emitting diodes (LEDs).

6. A system as recited in claim 1, wherein the second light generator produces light at a wavelength of light that is produced by the first light generator.

7. A system as recited in claim 1, wherein the first light has a spectrum different from a spectrum of the second light, the spectrum of the second light supplementing the spectrum of the first light to provide a desired color balance in the combined light beam.

8. A system as recited in claim 1, wherein the first and second light generators are each light generators of a first type of light generator comprising a lamp or a second type of light generator comprising a LED.

9. A system as recited in claim 8, wherein the first light generator is of the same type of light generator as the second light generator.

10. A system as recited in claim 1, further comprising an image relay system to relay an image an output of the homogenizer unit to the at least one image display unit.

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

12. A system as recited in claim 11, 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.

13. A system as recited in claim 12, wherein the tunnel integrator is a trapezoidal tunnel integrator.

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

15. A system 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.

16. A system 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.

17. A system as recited in claim 1, wherein the image display unit comprises at least one of a liquid crystal display unit and a micromechanical display having an array of tiltable mirrors.

18. A system as recited in claim 1, further comprising a first reflector associated with the first light generator to collect the first light and direct the collected first light towards the light combiner and further comprising a second reflector associated with the second light generator to collect the second light and direct the collected second light towards the light combiner.

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

a first light generator producing first light;

a second light generator producing second light;

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.

20. A system as recited in claim 19, further comprising an index matching layer disposed between the first and second prisms, the second light that is substantially transmitted through the first and second prisms passing through the index-matching layer.

21. A system as recited in claim 20, wherein the index-matching layer is an adhesive layer.

22. A system as recited in claim 21, wherein the first light totally internally reflects within the first prism at a surface area substantially free of the refractive index-matching layer.

23. A system as recited in claim 19, wherein the first light generator comprises a lamp to generate the first light.

24. A system as recited in claim 19, wherein at least the first light generator comprises one or more light emitting diodes (LEDs).

25. A system as recited in claim 19, wherein the second light generator produces light at a wavelength of light that is produced by the first light generator.

26. A system as recited in claim 19, wherein the first light has a spectrum different from a spectrum of the second light, the spectrum of the second light supplementing the spectrum of the first light to provide a desired color balance in the combined light beam.

27. A system as recited in claim 19, wherein the first and second light generators are each light generators of a first type of light generator comprising a lamp or a second type of light generator comprising a LED.

28. A system as recited in claim 27, wherein the first light generator is of the same type of light generator as the second light generator.

29. A system as recited in claim 19, further comprising a first reflector associated with the first light generator to collect the first light and direct the collected first light towards the light combiner and further comprising a second reflector associated with the second light generator to collect the second light and direct the collected second light towards the light combiner.

30. A system as recited in claim 19, wherein the integrator is a tunnel integrator.

31. A system as recited in claim 19, wherein the tunnel integrator is a tapered integrator.