Illumination system and projector adopting the same

• US 20040012831A1
• Filed: 10/10/2002
• Published: 01/22/2004
• Est. Priority Date: 10/12/2001
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Sung-Ha, Sokolov, Kirill Sergeevich
• Granted Patent: US 6,799,849 B2
• Time in Patent Office: Days
• US Class Current: 359/15
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• 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

An illumination system includes an illumination unit having at least one light emitting device which emits a light beam of a predetermined wavelength and at least one holographic optical element which reduces a cross section of the light beam emitted from the light emitting device, and an optical path changer which changes a proceeding path of an incident light passing through the holographic optical element. A projector includes at least one illumination unit having at least one light emitting device which emits a light beam of a predetermined wavelength and at least one holographic optical element which reduces a cross section of the light beam emitted from the light emitting device, an optical path changer which changes a proceeding path of an incident light input through the holographic optical element, a display device which forms an image by processing a light beam input from the optical path changer according to an image signal, and a projection lens unit which magnifies the image formed by the display device and projects the magnified image toward a screen.

Claims

1. An illumination system comprising:

an illumination unit which includes;

at least one light emitting device which emits a light beam having a predetermined wavelength, and

at least one holographic optical element which reduces a cross section of the light beam emitted from the light emitting device; and

an optical path changer which changes a proceeding path of an incident light passing through the holographic optical element.

2. The illumination system as claimed in claim 1, wherein the light emitting device includes a light emitting device having an array structure.

3. The illumination system as claimed in claim 2, wherein the light emitting device is one of a light emitting diode (LED), a laser diode (LD), an organic electro luminescent (EL), and a field emission display (FED).

4. The illumination system as claimed in claim 3, wherein:

the at least one holographic optical element comprises;

a first holographic optical element which changes a proceeding direction of the light beam emitted from the light emitting device; and

a second holographic optical element which reduces a diffraction angle of an incident light beam of which the proceeding direction is changed by the first holographic optical element, and

the at least one holographic optical element reduces a cross section of an incident light beam where the light beam is reflected by the optical path changer.

5. The illumination system as claimed in claim 4, wherein the first holographic optical element allows an incident light beam to be incident on the second holographic optical element at a predetermined angle of inclination and to be a parallel light beam.

6. The illumination system as claimed in claim 5, wherein the optical path changer is a reflection mirror.

7. The illumination system as claimed in claim 5, wherein the optical path changer comprises:

a first optical path changer which changes the proceeding path of the incident light passing through the holographic optical element; and

a second optical path changer which changes a proceeding path of the light beam passing through the first optical path changer by selectively transmitting or reflecting the light beam.

8. The illumination system as claimed in claim 7, wherein:

the illumination unit comprises a plurality of illumination units which emit light beams having different wavelengths, and

the illumination units are arranged in a line in a horizontal direction.

9. The illumination system as claimed in claim 8, wherein the second optical path changer is a dichroic filter which reflects or transmits a light beam passing through the first optical path changer according to a wavelength thereof.

10. The illumination system as claimed in claim 7, wherein the second optical path changer is a cholesteric band modulation filter which reflects or transmits the light beam passing through the first optical path changer according to a polarization direction and a wavelength thereof.

11. The illumination system as claimed in claim 10, wherein the cholesteric band modulation filter comprises:

a first mirror surface which reflects a light beam of a right circular polarization and transmits a light beam of a left circular polarization, with respect to a beam light having a predetermined wavelength; and

a second mirror surface which transmits the light beam of the right circular polarization and reflects the light beam of the left circular polarization, with respect to the beam light having the predetermined wavelength.

12. The illumination system as claimed in claim 8, wherein the illumination units are further arranged in a multi-layer structure.

13. The illumination system as claimed in claim 7, wherein:

the illumination unit comprises a plurality of illumination units which emit light beams having different wavelengths, and

the illumination units are arranged to be separated from one another at a predetermined angle.

14. The illumination system as claimed in claim 13, wherein the second optical path changer is one of an X prism and an X type dichroic filter.

15. The illumination system as claimed in claim 13, wherein the illumination units are further arranged in a multi-layer structure.

16. The illumination system as claimed in claim 13, further comprising a parallel light beam forming unit which produces a light beam emitted from a corresponding light emitting device or light emitting device array into a parallel light beam.

17. The illumination system as claimed in claim 16, wherein the parallel light beam forming unit is one of a collimating lens array and a Fresnel lens array.

18. An illumination system comprising:

at least one light emitting device or light emitting device array which emits a light beam having a wavelength;

a first holographic optical element which condenses the light beam emitted from the light emitting device or light emitting device array;

a second holographic optical element which produces an incident light beam passing through the first holographic optical element into a parallel light beam with a reduced cross section thereof;

a third holographic optical element which reduces a diffraction angle of an incident light beam which is made into the parallel light beam by the second holographic optical element; and

an optical path changer which changes a proceeding path of an incident light beam passing through the third holographic optical element.

19. The illumination system as claimed in claim 18, wherein the light emitting device or light emitting device array is one of a light emitting diode (LED), a laser diode (LD), an organic electro luminescent (EL), and a field emission display (FED).

20. The illumination system as claimed in claim 19, wherein the optical path changer is a reflection mirror.

21. The illumination system as claimed in claim 19, wherein the optical path changer comprises:

a first optical path changer which changes the proceeding path of the incident light passing through the third holographic optical element; and

a second optical path changer which changes a proceeding path of the light beam passing through the first optical path changer by selectively transmitting or reflecting the light beam.

22. The illumination system as claimed in claim 21, wherein:

the at least one light emitting device or light emitting device array comprises a plurality of light emitting devices or light emitting device arrays which emit light beams having different wavelengths, and

the light emitting devices or light emitting device arrays are arranged in a line in a horizontal direction.

23. The illumination system as claimed in claim 22, wherein the second optical path changer is a dichroic filter which reflects or transmits a light beam passing through the first optical path changer according to a wavelength thereof.

24. The illumination system as claimed in claim 22, wherein the second optical path changer is a cholesteric band modulation filter which reflects or transmits a light beam passing through the first optical path changer according to a polarization direction and a wavelength thereof.

25. The illumination system as claimed in claim 22, wherein the cholesteric band modulation filter comprises:

a first mirror surface which reflects a light beam of a right circular polarization and transmits a light beam of a left circular polarization, with respect to a beam light having a predetermined wavelength; and

a second mirror surface which transmits the light beam of the right circular polarization and reflects the light beam of the left circular polarization, with respect to the beam light having the predetermined wavelength.

26. The illumination system as claimed in claim 22, wherein the light emitting devices or light emitting device arrays, the first through third holographic optical elements, and the first optical path changer are further arranged in a multi-layer structure so as to secure a sufficient amount of light.

27. The illumination system as claimed in claim 21, wherein:

the at least one light emitting device or light emitting device array comprises a plurality of light emitting devices or light emitting device arrays which emit light beams having different wavelengths, and

the light emitting devices or light emitting device arrays are arranged to be separated from one another at a predetermined angle.

28. The illumination system as claimed in claim 27, wherein the second optical path changer is one of an X prism and an X type dichroic filter.

29. The illumination system as claimed in claim 26, wherein the light emitting devices or light emitting device arrays, the first through third holographic optical elements, and the first optical path changer are further arranged in a multi-layer structure so as to secure a sufficient amount of light.

30. The illumination system as claimed in claim 29, wherein the multi-layer structure is in a symmetrical structure so as to have one or more of the light emitting devices or light emitting device arrays face each other.

31. The illumination system as claimed in claim 27, further comprising a parallel light beam forming unit which makes a light beam emitted from a corresponding one of the light emitting devices or light emitting device arrays into a parallel light beam.

32. The illumination system as claimed in claim 27, wherein a third holographic optical element of a corresponding one of the light emitting devices or light emitting device arrays is disposed on a plane different from a plane of a neighboring third holographic optical element and does not prevent a proceeding path of a light beam from the neighboring third holographic optical element.

33. The illumination system as claimed in claim 19, further comprising a parallel light beam forming unit which produces the light beam emitted from the light emitting device or light emitting device array into a parallel light beam.

34. The illumination system as claimed in claim 33, wherein the parallel light beam forming unit is one of a collimating lens array and a Fresnel lens array.

35. A projector comprising:

at least one illumination unit which includes;

at least one light emitting device which emits a light beam having a predetermined wavelength, and

at least one holographic optical element which reduces a cross section of the light beam emitted from the light emitting device;

an optical path changer which changes a proceeding path of an incident light input through the holographic optical element;

a display device which processes an image signal of a light beam input from the optical path changer and forms an image thereof; and

a projection lens unit which magnifies the image formed by the display device and projects the magnified image.

36. The projector as claimed in claim 35, wherein the light emitting device includes a light emitting device having an array structure.

37. The projector as claimed in claim 36, wherein the light emitting device is one of a light emitting diode (LED), a laser diode (LD), an organic electro luminescent (EL), and a field emission display (FED).

38. The projector as claimed in claim 37, wherein:

the at least one holographic optical element comprises;

a first holographic optical element which changes a proceeding direction of the light beam emitted from the light emitting device; and

a second holographic optical element which reduces a diffraction angle of an incident light beam of which the proceeding direction is changed by the first holographic optical element, and

the at least one holographic optical element reduces a cross section of an incident light beam where the light beam is reflected by the optical path changer.

39. The projector as claimed in claim 38, wherein the first holographic optical element allows an incident light beam to be incident on the second holographic optical element at a predetermined angle of inclination and to be a parallel light beam.

40. The projector as claimed in claim 38, wherein the at least one holographic optical element further comprises:

a third holographic optical element which condenses the light beam emitted from the light emitting device;

a fourth holographic optical element which produces the incident light beam passing through the third holographic optical element into a parallel light beam with a reduced cross section thereof; and

a fifth holographic optical element which reduces a diffraction angle of the incident light beam which is made parallel by the fourth holographic optical element.

44. The projector as claimed in claim 43, wherein a fifth holographic optical element of a corresponding one of the illumination units is disposed on a plane different from a plane of a neighboring fifth holographic optical element and does not prevent a proceeding path of a light beam from the neighboring fifth holographic optical element.

41. The projector as claimed in claim 40, wherein the optical path changer is a reflection mirror.

42. The projector as claimed in claim 40, wherein the optical path changer comprises:

a first optical path changer which changes the proceeding path of the incident light input through the holographic optical element; and

a second optical path changer which changes a proceeding path of the light beam passing through the first optical path changer by selectively transmitting or reflecting the light beam.

43. The projector as claimed in claim 42, wherein:

the at least one illumination unit comprises a plurality of illumination units which emit light beams having different wavelengths, and

the illumination units are arranged in a line in a horizontal direction.

45. The projector as claimed in claim 43, wherein the second optical path changer is a dichroic filter which reflect or transmits a light beam passing through the first optical path changer according to a wavelength thereof.

46. The projector as claimed in claim 43, wherein the second optical path changer is a cholesteric band modulation filter which reflects or transmits a light beam passing through the first optical path changer according to a polarization direction and a wavelength thereof.

47. The projector as claimed in claim 46, wherein the cholesteric band modulation filter comprises:

a first mirror surface which reflects a light beam of a right circular polarization and transmits a light beam of left circular polarization, with respect to a beam light having a predetermined wavelength; and

a second mirror surface which transmits the light beam of the right circular polarization and reflects the light beam of the left circular polarization, with respect to the beam light having the predetermined wavelength.

48. The projector as claimed in claim 42, wherein:

the at least one illumination unit comprises a plurality of illumination units which emit light beams having different wavelengths, and

the illumination units are arranged to be separated from one another at a predetermined angle.

49. The projector as claimed in claim 48, wherein the second optical path changer is one of an X prism and an X type dichroic filter.

50. The projector as claimed in claim 48, wherein the illumination units are further arranged in a multi-layer structure.

51. The projector as claimed in claim 48, further comprising a parallel light beam forming unit which makes a light beam emitted from a corresponding one of the light emitting devices or light emitting device arrays into a parallel light beam.

52. The projector as claimed in claim 51, wherein the parallel light beam forming unit is one of a collimating lens array and a Fresnel lens array.

58. The projector as claimed in claim 35, further comprising:

a fly eye lens which uniformly distributes light beams proceeding in the same direction through the optical path changer; and

a relay lens which condenses the light beams toward the display device.

59. The projector as claimed in claim 35, wherein the display device is a mobile mirror apparatus which includes one or more micromirrors, and realizes the image by on/off switching operations of the one or more micromirrors according to the image signal.

60. The projector as claimed in claim 35, wherein the display device is an LCD device which realizes the image by polarizing and modulating an incident light beam.

53. An illumination system comprising:

at least one illumination unit which includes;

at least one light emitting device which emits a light beam having a predetermined wavelength, and

at least one diffractive optical device which reduces a cross section of the light beam emitted from the light emitting device; and

an optical path changer which changes a proceeding path of an incident light beam input through the diffractive optical device.

54. The illumination system as claimed in claim 53, wherein the light emitting device includes a light emitting device having an array structure.

55. The illumination system as claimed in claim 54, wherein the light emitting device is one of a light emitting diode (LED), a laser diode (LD), an organic electro luminescent (EL), and a field emission display (FED).

56. The illumination system as claimed in claim 55, wherein the at least one diffractive optical device comprises:

a first diffractive optical device which changes a proceeding direction of the light beam emitted from the light emitting device; and

a second diffractive optical device which reduces a diffraction angle of an incident light beam, of which the proceeding direction is changed by the first diffractive optical device, so as to reduce a cross section of an incident light beam where the light beam is reflected by the first optical path changer.

57. The illumination system as claimed in claim 55, wherein the at least one diffractive optical device comprises:

a first diffractive optical device which condenses the light beam emitted from the light emitting device;

a seond diffractive optical device which produces an incident light beam passing through the third diffractive optical device into a parallel light beam with a reduced cross section thereof; and

a third diffractive optical device which reduces a diffraction angle of an incident light beam which is made parallel by the second diffractive optical device.