Illumination system and projection display device employing the same

• US 6,902,310 B2
• Filed: 01/30/2003
• Issued: 06/07/2005
• Est. Priority Date: 02/01/2002
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Im, Yong-seok
• Primary Examiner(s): Husar, Stephen
• Assistant Examiner(s): Ton, Anabel
• Application Number:
  US10/353,948
• Publication Number:
  US 20030147255A1
• Time in Patent Office: 859 Days
• Field of Search: 362/558, 362/551, 362/231, 362/555, 362/553, 362/309, 362/268, 362/328, 362/240, 359/618, 359/15, 359/13
• US Class Current: 362/558
• CPC Class Codes: G02B 27/18 for optical projection, e.g. combination of mirror and condenser and objective photographic, cine and overhead projectors G03B21/00; photographic projection printing G03B27/32; photolithographic projectors G03F7/20; projection television H04N5/74; colour projection television H04N9/31
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• 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

Abstract

A compact illumination system using a light source such as an array of light emitting diodes (LEDs) or laser diodes (LDs) having a long life span, and a projection display device employing the illumination system are provided. The illumination system includes a light source; a collimating lens array for making light emitted form the light source be parallel; an optical path conversion unit for reflecting the light incident in parallel from the collimating lens array back toward the light source to initially converge the light; and a secondary focusing lens disposed at a side where the light source is positioned, for converging the light, that has been reflected and converged through the optical path conversion unit, on a predetermined position. The illumination system reflected the light emitted from the light source back toward the light source through the optical path conversion unit so that the volumes of the illumination system can be greatly reduced to be compact.

Claims

1. An illumination system comprising:

a light source;

a collimating lens array for making light emitted form the light source be parallel;

an optical path conversion unit for reflecting the light incident in parallel from the collimating lens array back toward the light source to initially converge the light; and

a secondary focusing lens disposed at a side where the light source is positioned, for converging the light, that has been reflected and converged through the optical path conversion unit, on a predetermined position.

2. The illumination system of claim 1, wherein the optical path conversion unit comprises:

a Fresnel lens for converging the parallel light incident from the collimating lens array; and

a mirror for converting a path of the light transmitted through the Fresnel lens toward the secondary focusing lens.

3. The illumination system of claim 2, further comprising an optical fiber for leading the light that has been converged through the secondary focusing lens.

4. The illumination system of claim 3, wherein the Fresnel lens is separated from the mirror by a predetermined gap, and the gap is variable.

5. The illumination system of claim 1, wherein the optical path conversion unit comprises:

an initial focusing lens having at least one convex side; and

a mirror for converting a path of the light transmitted through the initial focusing lens toward the secondary focusing lens.

6. The illumination system of claim 5, further comprising an optical fiber for leading the light that has been converged through the secondary focusing lens.

7. The illumination system of claim 6, wherein the initial focusing lens is separated from the mirror by a predetermined gap, and the gap is variable.

8. The illumination system of claim 1, wherein the optical path conversion unit has at least one convex plane and a reflective coating on its back side.

9. The illumination system of claim 1, wherein the optical path conversion unit is a Fresnel lens comprising a reflective coating on the back thereof so that the parallel light incident from the collimating lens array is reflected and converged.

10. The illumination system of claim 9, further comprising an optical fiber for leading the light that has been converged through the secondary focusing lens.

11. The illumination system of claim 1, wherein the optical path conversion unit is a holographic optical element.

12. The illumination system of claim 1, wherein the optical path conversion unit is a spherical concave mirror.

13. The illumination system of claim 1, wherein the light source is composed of light emitting diodes or laser diodes.

14. The illumination system of claim 13, wherein the light source has an array structure.

15. The illumination system of claim 13, wherein the light source comprises a plurality of light emitters arranged in the array structure, the light emitters emitting light of different wavelengths.

16. The illumination system of claim 13, wherein the collimating lens array comprises a first cylindrical convex lens for compensating for a saggital plane of the light and a second cylindrical convex lens for compensating for a tangential plane of the light.

17. The illumination system of claim 13, wherein the collimating lens array is an aspherical fly-eye lens system.

18. The illumination system of claim 13, wherein the collimating lens array comprises a cylindrical convex lens for compensating for a saggital or tangential plane of the light and a spherical convex lens for performing compensation on the light transmitted through the cylindrical convex lens.

19. A projection display device which forms a color image from light emitted from an illumination system using a display device according to an image signal and magnifically project the color image on a screen, wherein the illumination system comprises:

a light source;

a collimating lens array for making light emitted form the light source be parallel;

an optical path conversion unit for reflecting the light incident in parallel from the collimating lens array back toward the light source to initially converge the light; and

a secondary focusing lens disposed at a side where the light source is positioned, for converging the light, that has been reflected and converged through the optical path conversion unit, on a predetermined position.

20. The projection display device of claim 19, wherein the optical path conversion unit comprises:

a Fresnel lens for converging the parallel light incident from the collimating lens array; and

a mirror for converting a path of the light transmitted through the Fresnel lens toward the secondary focusing lens.

21. The projection display device of claim 20, wherein the Fresnel lens is separated from the mirror by a predetermined gap.

22. The projection display device of claim 21, further comprising an optical fiber for leading the light that has been converged through the secondary focusing lens.

23. The projection display device of claim 19, wherein the optical path conversion unit comprises:

an initial focusing lens having at least one convex side; and

a mirror for converting a path of the light transmitted through the initial focusing lens toward the secondary focusing lens.

24. The projection display device of claim 23, further comprising an optical fiber for leading the light that has been converged through the secondary focusing lens.

25. The projection display device of claim 19, wherein the optical path conversion unit has at least one convex plane and a reflective coating on its back side.

26. The projection display device of claim 19, wherein the optical path conversion unit is a Fresnel lens comprising a reflective coating on the back thereof so that the parallel light incident from the collimating lens array is reflected and converged.

27. The projection display device of claim 19, wherein the optical path conversion unit is a holographic optical element.

28. The projection display device of claim 19, wherein the optical path conversion unit is a spherical concave mirror.

29. The projection display device of claim 19, further comprising an optical fiber for leading the light that has been converged through the secondary focusing lens.

30. The projection display device of claim 19, wherein the light source is composed of light emitting diodes or laser diodes.

31. The projection display device of claim 30, wherein the light source has an array structure.

32. The projection display device of claim 30, wherein the light source comprises a plurality of light emitters arranged in the array structure, the light emitters emitting light of different wavelengths.

33. The projection display device of claim 30, wherein the collimating lens array comprises a first cylindrical convex lens for compensating a saggital plane of the light and a second cylindrical convex lens for compensating a tangential plane of the light.

34. The projection display device of claim 30, wherein the collimating lens array is an aspherical fly-eye lens system.

35. The projection display device of claim 30, wherein the collimating lens array comprises a cylindrical convex lens for compensating for a saggital or tangential plane of the light and a spherical convex lens for performing compensation on the light transmitted through the cylindrical convex lens.