Color separating optical system, image display optical system, and projection image display apparatus

• US 7,156,520 B2
• Filed: 09/04/2002
• Issued: 01/02/2007
• Est. Priority Date: 09/04/2001
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Abe, Masayuki, Okuyama, Atsushi, Chigira, Tatsuo
• Primary Examiner(s): KOVAL, MELISSA J
• Application Number:
  US10/235,975
• Publication Number:
  US 20030067586A1
• Time in Patent Office: 1,581 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/52, 353/81, 349/8, 349/9
• US Class Current: 353/20
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• 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 9/3117 by using a sequential colour filter producing two or more colours simultaneously, e.g. by creating scrolling colour bands
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A color separating-combining optical system is configured to separate illumination light into a plurality of color spectrums, guiding these color spectrums to respective image display elements, and combining the color spectrums modulated by the image display elements. The system includes a first polarization separating optical system that reflects the first color spectrum from the separating optical system to a first image display element and transmits the first color spectrum from the first image display element to the combining optical system. Similarly, a second polarization separating optical system is provided that reflects and transmits the second color spectrum. The degree of linear polarization of a reflected color can be maintained higher than that of another, and/or an antireflection element can be included in the path of reflected light.

Claims

1. A color separating-combining optical system

comprising:

a separating optical system which separates illumination light into a first color spectrum and a second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a first polarization separating optical system with a first polarization separating surface, which reflects said first color spectrum from said separating optical system to a first image display element, and transmits said first color spectrum from said first image display element to said combining optical system; and

a second polarization separating optical system with a second polarization separating surface, which reflects said second color spectrum from said separating optical system to a second image display element, and transmits said second color spectrum from said second image display element to said combining optical system,

wherein a degree of linear polarization of said first color spectrum reflected by said first polarization separating surface is higher than a degree of linear polarization of said second color spectrum reflected by said second polarization separating surface.

2. A color separating-combining optical system comprising:

a separating optical system which separates illumination light into a first color spectrum and a second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a first polarization separating optical system with a first polarization separating surface, which reflects said first color spectrum from said separating optical system to a first image display element, and transmits said first color spectrum from said first image display element to said combining optical system; and

a second polarization separating optical system with a second polarization separating surface, which reflects said second color spectrum from said separating optical system to a second image display element, and transmits said second color spectrum from said second image display element to said combining optical system,

wherein a degree of linear polarization of said first color spectrum transmitted by said first polarization separating surface is higher than a degree of linear polarization of said second color spectrum transmitted by said second polarization separating surface.

3. A color separating-combining optical system comprising:

a separating optical system which separates illumination light into a first color spectrum and a second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a first polarization separating optical system with a first polarization separating surface, which transmits said first color spectrum from said separating optical system to a first image display element, and reflects said first color spectrum from said first image display element to said combining optical system; and

a second polarization separating optical system with a second polarization separating surface, which transmits said second color spectrum from said separating optical system to a second image display element, and reflects said second color spectrum from said second image display element to said combining optical system,

wherein a degree of linear polarization of said first color spectrum transmitted by said first polarization separating surface is higher than a degree of linear polarization of said second color spectrum transmitted by said second polarization separating surface.

4. A color separating-combining optical system comprising:

a separating optical system which separates illumination light into a first color spectrum and a second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a first polarization separating optical system with a first polarization separating surface, which transmits said first color spectrum from said separating optical system to a first image display element, and reflects said first color spectrum from said first image display element to said combining optical system; and

a second polarization separating optical system with a second polarization separating surface, which transmits said second color spectrum from said separating optical system to a second image display element, and reflects said second color spectrum from said second image display element said combining optical system,

wherein a degree of linear polarization of said first color spectrum reflected by said first polarization separating surface is higher than a degree of linear polarization of said second color spectrum reflected by said second polarization separating surface.

5. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a first color spectrum and a second color spectrum;

a first image display element which modulates said first color spectrum;

a second image display element which modulates said second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating optical system with a first polarization separating surface, which reflects said first color spectrum from said separating optical system to said first image display element, and transmits said first color spectrum from said first image display element to said combining optical system, and

a second polarization separating optical system with said second polarization separating surface, which reflects said second color spectrum from said separating optical system to a second image display element, and transmits said second color spectrum from said second image display element to said combining optical system,

wherein a degree of linear polarization of said first color spectrum reflected by said first polarization separating surface is higher than a degree of linear polarization of said second color spectrum reflected by said second polarization separating surface.

6. A projection type image display apparatus according to claim 5, wherein said first color spectrum includes light of green, and said second color spectrum includes light of blue or red.

7. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a light of green and a light of blue and red;

a green light image display element which modulates said light of green;

a blue light image display element which modulates said light of blue;

a red light image display element which modulates said light of red;

a combining optical system which combines said light of green and said light of blue and red;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating optical system with a first polarization separating surface, which reflects said light of green from said separating optical system to said green light image display element, and transmits said light of green from said green light image display element to said combining optical system; and

a second polarization separating optical system with said second polarization separating surface, which reflects said light of blue from said separating optical system to said blue light image display element, and transmits said light of blue from said blue light image display element to said combining optical system, and which reflects said light of red from said separating optical system to said red light image display element, and transmits said light of red from said red light image display element to said combining optical system,

wherein a degree of linear polarization of said light of green reflected by said first polarization separating surface is higher than a degree of linear polarization of said light of red reflected by said second polarization separating surface.

8. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a first color spectrum and a second color spectrum;

a first image display element which modulates said first color spectrum;

a second image display element which modulates said second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating optical system with a first polarization separating surface, which reflects said first color spectrum from said separating optical system to said first image display element, and transmits said first color spectrum from said first image display element to said combining optical system; and

a second polarization separating optical system with said second polarization separating surface, which reflects said second color spectrum from said separating optical system to a second image display element, and transmits said second color spectrum from said second image display element to said combining optical system,

wherein a degree of linear polarization of said first color spectrum transmitted by said first polarization separating surface is higher than a degree of linear polarization of said second color spectrum transmitted by said second polarization separating surface.

9. A projection type image display apparatus according to claim 8, wherein said first color spectrum includes light of green, and said second color spectrum includes light of blue or red.

10. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a light of green and a light of blue and red;

a green light image display element which modulates said light of green;

a blue light image display element which modulates said light of blue;

a red light image display element which modulates said light of red;

a combining optical system which combines said light of green and said light of blue and red;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating optical system with a first polarization separating surface, which reflects said light of green from said separating optical system to said green light image display element, and transmits said light of green from said green light image display element to said combining optical system; and

a second polarization separating optical system with said second polarization separating surface, which reflects said light of blue from said separating optical system to said blue light image display element, and transmits said light of blue from said blue light image display element to said combining optical system, and which reflects said light of red from said separating optical system to said red light image display element, and transmits said light of red from said red light image display element to said combining optical system,

wherein a degree of linear polarization of said light of green transmitted by said first polarization separating surface is higher than a degree of linear polarization of said light of red transmitted by said second polarization separating surface.

11. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a first color spectrum and a second color spectrum;

a first image display element which modulates said first color spectrum;

a second image display element which modulates said second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating optical system with a first polarization separating surface, which transmits said first color spectrum from said separating optical system to said first image display element, and reflects said first color spectrum from said first image display element to said combining optical system; and

a second polarization separating optical system with said second polarization separating surface, which transmits said second color spectrum from said separating optical system to said second image display element, and reflects said second color spectrum from said second image display element to said combining optical system,

wherein a degree of linear polarization of said first color spectrum transmitted by said first polarization separating surface is higher than a degree of linear polarization of said second color spectrum transmitted by said second polarization separating surface.

12. A projection type image display apparatus according to claim 11, wherein the degree of linear polarization of said first color spectrum transmitted by said first polarization surface is higher than a degree of linear polarization of said first color spectrum reflected by said first polarization surface.

13. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a first color spectrum and a second color spectrum;

a first image display element which modulates said first color spectrum;

a second image display element which modulates said second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating optical system with a first polarization separating surface, which transmits said first color spectrum from said separating optical system to said first image display element, and reflects said first color spectrum from said first image display element to said combining optical system; and

a second polarization separating optical system with said second polarization separating surface, which transmits said second color spectrum from said separating optical system to a second image display element, and reflects said second color spectrum from said second image display element to said combining optical system,

wherein a degree of linear polarization of said first color spectrum reflected by said first polarization separating surface is higher than a degree of linear polarization of said second color spectrum reflected by said second polarization separating surface.

14. A projection type image display apparatus according to claim 13, wherein the degree of linear polarization of said first color spectrum transmitted by said first polarization surface is higher than a degree of linear polarization of said first color spectrum reflected by said first polarization surface.

15. A color separating-combining optical system comprising:

a separating optical system which separates illumination light into a first color spectrum and a second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a first polarization separating optical system which reflects said first color spectrum from said separating optical system to a first image display element, and transmits said first color spectrum from said first image display element to said combining optical system;

a second polarization separating optical system which guides said second color spectrum from said separating optical system to a second image display element, and guides said second color spectrum from said second image display element to said combining optical system; and

an antireflection element which is located on an optical path of said first color spectrum from said separating optical system, which should be reflected by said first polarization separating optical system but transmits said first polarization separating optical system.

16. A color separating-combining optical system comprising:

a separating optical system which separates illumination light into a first color spectrum and a second color spectrum;

a combining optical system with polarization separating surface, which combines said first color spectrum and said second color spectrum, by reflecting said first color spectrum and transmitting said second color spectrum;

a first polarization separating optical system which guides said first color spectrum from said separating optical system to a first image display element, and guides said first color spectrum from said first image display element to said combining optical system;

a second polarization separating optical system which guides said second color spectrum from said separating optical system to a second image display element, and guides said second color spectrum from said second image display element to said combining optical system; and

an antireflection element which is located in an optical path of said first color spectrum which should be reflected by said first polarization separating optical system but transmitted by said combining optical system.

17. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a first color spectrum and a second color spectrum;

a first image display element which modulates said first color spectrum;

a second image display element which modulates said second color spectrum;

a combining optical system which combines said first color spectrum and said second color spectrum;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating separating optical system which reflects said first color spectrum from said separating optical system to a first image display element, and transmits said first color spectrum from said first image display element to said combining optical system;

a second polarization separating optical system which guides said second color spectrum from said separating optical system to a second image display element, and guides said second color spectrum from said second image display element to said combining optical system; and

an antireflection element which is located on an optical path of said first color spectrum from said separating optical system, which should be reflected by said first polarization separating optical system but transmitted by said first polarization separating optical system.

18. A projection type image display apparatus according to claim 17 wherein said first polarization separating optical system has a shape of prism, and said antireflection element is adhered with the prism surface of said first polarization separating optical system.

19. A projection type image display apparatus according to claim 18 wherein said antireflection element has a heat radiating member located on a side opposed to a side adhered with said first polarization separating surface.

20. A projection type image display apparatus according to claim 17, wherein said antireflection element has a surface with a predetermined surface roughness.

21. A projection type image display apparatus according to claim 17, wherein said antireflection element has a surface on which light-absorbing paint is coated.

22. A projection type image display apparatus according to claim 17, wherein said first color spectrum includes a light of green, and said second color spectrum includes a light of blue or red.

23. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a light of green and a light of blue or red;

a green light image display element which modulates said light of green;

a blue light image display element which modulates said light of blue;

a red light image display element which modulates said light of red;

a combining optical system which combines said light of green and said light of blue and red;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating optical system which reflects said light of green from said separating optical system to said green light image display element, and transmits said light of green from said green light image display element to said combining optical system;

a second polarization separating optical system which guides said light of blue from said separating optical system to said blue light image display element,and guides said light of blue from said blue light image display element to said combining optical system, and which guides said light of red from said separating optical system to said red light image display element, and guides said light of red from said red light image display element to said combining optical system; and

an antireflection element which is located on an optical path of said light of green from said separating optical system, which should be reflected by said first polarization separating optical system but transmitted by said first polarization separating optical system.

24. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light into a first color spectrum and a second color spectrum;

a first image display element which modulates said first color spectrum;

a second image display element which modulates said second color spectrum;

a combining optical system with polarization separating surface, which combines said first color spectrum and said second color spectrum, by reflecting said first color spectrum and transmitting said second color spectrum;

a projecting optical system which projects a combined light from said combining optical system;

a first polarization separating optical system which guides said first color spectrum from said separating optical system to said first image display element, and guides said first color spectrum from said first image display element to said combining optical system.

a second polarization separating optical system which guides said second color spectrum from said separating optical system to said second image display element, and guides said second color spectrum from said second image display element to said combining optical system; and

an antireflection element which is located on an optical path of said first color spectrum which should be reflected by said combining optical system but transmitted by said combining optical system.

25. A projection type image display apparatus according to claim 24, wherein said first color spectrum includes a light of green, and said second color spectrum includes a light of blue or red.

26. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light from said illumination system into a light of green and a light of blue and red;

a green light image display element which modulates said light of green;

a blue light image display element which modulates said light of blue;

a red light image display element which modulates said light of red;

a combining optical system with a polarization separating surface, which combines said light of green and said light of blue and red, by reflecting said light of green and by transmitting said light of blue and red;

a projecting optical system which projects combined light from said combining optical system;

a first polarization separating optical system which guides said light of green from said separating optical system to said green light image display element, and guides said light of green from said green light image display element to said combining optical system;

a second polarization separating optical system which guides said light of blue from said separating optical system to said blue light image display element, and guides said light of blue from said blue light image display element to said combining optical system, and which guides said light of red from said separating optical system to said red light image display element, and guides said light of red from said red light image display element to said combining optical system; and

an antireflection element which is located on an optical path of said light of green from said separating optical system, which should be reflected by said combining optical system but transmitted by said combining optical system.

27. A projection type image display apparatus comprising:

an illumination system;

a separating optical system which separates illumination light into a first color spectrum and a second color spectrum;

a first image display element which modulates said first color spectrum;

a second image display element which modulates said second color spectrum;

a combining optical system with polarization separating surface, which combines said first color spectrum and said second color spectrum, by reflecting said first color spectrum and transmitting said second color spectrum;

a projecting optical system which projects a combined light from said combining optical system;

a first polarization separating optical system which reflects said first color spectrum from said separating optical system to said first image display element, and transmits said first color spectrum from said first image display element to said combining optical system;

a second polarization separating optical system which guides said second color spectrum from said separating optical system to said second image display element, and guides said second color spectrum from said second image display element to said combining optical system;

a first antireflection element which is located on an optical path of said first color spectrum which should be reflected by said first polarization separating optical system but transmitted by said first polarization separating optical system; and

a second antireflection element which is located on an optical path of said second color spectrum which should be reflected by said second polarization separating optical system but transmitted by said second polarization separating optical system.

28. A color separating-combining optical system comprising:

a first image display element, a second image display element, and a third image display element;

color spectrum separating means for separating an illumination light into a green spectrum, and a blue spectrum and a red spectrum;

a first polarization separating surface for making, by a polarization separation effect, an optical path along which the green spectrum is incident into the first image display element from the color spectrum separating means, different from an optical path along which the green spectrum is emerged from the first image display element;

a second polarization separating surface for separating, by a polarization separation effect the blue spectrum and the red spectrum from the color spectrum separating means independently, and for making, by a polarization separation effect, an optical path along which the blue spectrum is incident into the second image display element, different from an optical path along which the blue spectrum is emerged from the second image display element, and an optical path along which the red spectrum is incident into the third image display element, different from an optical path along which the red spectrum is emerged from the third image display element; and

a third polarization separating surface for combining the green spectrum from the first polarization separating surface, with the blue spectrum and the red spectrum from the second polarization separating surface,

wherein a polarization separation characteristic of the first polarization separating surface is made different from a polarization separation characteristic of the second polarization separating surface, so that when a ratio of a component of main polarized direction of the green spectrum, blue spectrum and red spectrum is assumed as a degree of linear polarization, a degree of linear polarization of the green spectrum at the time of being incident into the first image display element from the first polarization separating surface is higher than a degree of linear polarization of the blue spectrum at the time of being incident into the second image display element from the second polarization separating surface and a degree of linear polarization of the red spectrum at the time being incident into the third image display element from the second polarization separating surface.

29. A color separating-combining optical system according to claim 28, wherein the second polarization separating surface has a polarization separation characteristic of making a degree of linear polarization of blue spectrum reflected by the second polarization separating surface substantially equal to a degree of linear polarization of the blue spectrum transmitted through the second polarization separating surface, and making a degree of linear polarization of red spectrum reflected by the second polarization separating surface substantially equal to a degree of linear polarization of the red spectrum transmitted through the second polarization separating surface.

30. A color separating-combining optical system according to claim 28, wherein the first polarization separating surface has a polarization separation characteristic of making a degree of linear polarization of the green spectrum at the time of being incident into the first image display element from the first polarization separating surface, higher than a degree of linear polarization of green spectrum at the time of being incident into the third polarization separating surface from the first polarization separating surface through the first image display element.

31. A color separating-combining optical system according to claim 28, further comprising a polarization plate located between the first polarization separating surface and the third polarization separating surface.

32. A color separating-combining optical system according to claim 28, wherein the first image display element, second image display element and third image display element are reflection type image display elements.

33. A projection type image display apparatus comprising:

a color separating-combining optical system according to claim 28, an illumination optical system for making illumination light incident into the color separating-combining optical system at a state in which the polarized direction of the incident light is aligned; and

a projection optical system for projecting color light emerged from the color separating-combining optical system.