Optical element, polarization illumination device, and projection display apparatus

• US 5,978,136 A
• Filed: 12/17/1997
• Issued: 11/02/1999
• Est. Priority Date: 12/18/1996
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Yajima, Akitaka, Ogawa, Yasunori, Ushiyama, Tomiyoshi
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US08/992,012
• Time in Patent Office: 685 Days
• Field of Search: 359/487, 359/495, 359/497, 359/250, 359/252, 359/253, 359/256, 359/259, 359/619, 359/629, 359/634, 359/638, 359/621, 359/622, 359/626, 359/627, 353/20, 353/31, 353/32, 353/33, 353/34, 353/37, 349/5, 362/19
• US Class Current: 359/485.04
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/285 comprising arrays of elements, e.g. microprisms
• 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 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

Two polarization conversion element arrays are disclosed. Each polarization conversion element array is composed of a plurality of polarization conversion elements for converting light incident upon the polarization conversion element array to a linearly polarized light beam with a predetermined polarization direction. The plurality of polarization conversion elements are disposed opposite to each other with a predetermined space provided between at about the center of the light-outgoing surface of a lens array in the direction of arrangement. Of the light beams (s-polarized+p-polarized light beams) gathered by the lens array, light beam that is not incident upon the polarization conversion element and passes through the predetermined space is a light beam including a predetermined polarized light beam (s-polarized light beam) that is primarily made to leave the array 320a and an ineffective polarized light beam (p-polarized light beam). Of the light passing through and leaving the space, the required polarized light beam alone can be made to leave as an effective light beam by providing a polarization plate or the like at the light-outgoing side of the space.

Claims

1. An optical element comprising:

two polarization conversion element arrays for converting polarized light with random polarization directions to one type of polarized light,

wherein each of said two polarization conversion element arrays includes polarization separating surfaces for separating the polarized light with random polarization directions into two types of linearly polarized light and reflecting surfaces for reflecting one of the two types of the linearly polarized light produced by separation by said polarization separating surfaces, said polarization separating surfaces and said reflecting surfaces being alternately arranged between light-transmissive members, and

wherein said two polarization conversion element arrays are separated by a predetermined space with no elements disposed between the two polarization conversion element arrays, said polarization separating surfaces of one of said two polarization conversion element arrays are arranged opposite to said polarization separating surfaces of the other of said two polarization conversion element arrays with respect to the predetermined space.

2. An optical element according to claim 1, further comprising a dummy region including neither said polarization separating surfaces nor said reflecting surfaces, said dummy region being made of a transmissive material and disposed on an end at a predetermined space side of each of said two polarization conversion element arrays.

3. An optical element according to claim 1, further comprising a region including neither said polarization separating surfaces nor said reflecting surfaces, said region being made of a transmissive material and disposed on an end opposite to a predetermined space side of each of said two polarization conversion element arrays.

4. An optical element comprising:

a lens array composed of a plurality of lenses disposed in a matrix; and

two polarization conversion element arrays, affixed to one surface of said lens array, the two polarization conversion element arrays converting polarized light with random polarization directions to one type of polarized light,

wherein each of said two polarization conversion element arrays includes polarization separating surfaces for separating the polarized light with random polarization directions into two types of linearly polarized light and reflecting surfaces for reflecting one of the two types of the linearly polarized light produced by separation by said polarization separating surfaces, said polarization separating surfaces and said reflecting surfaces being alternately arranged between light-transmissive members, and

wherein said two polarization conversion element arrays are separated by a predetermined space with no elements disposed between the two polarization conversion element arrays, said polarization separating surfaces of one of said two polarization conversion element arrays are arranged opposite to said polarization separating surfaces of the other of said two polarization conversion element arrays with respect to the predetermined space.

5. An optical element according to claim 4, further comprising a dummy region including neither said polarization separating surfaces nor said reflecting surfaces, said dummy region being made of a transmissive material and disposed on an end at a predetermined space side of each of said two polarization conversion element arrays.

6. An optical element according to claim 5, wherein a corner at the side of the predetermined space side of said dummy region is removed.

7. An optical element according to claim 4, further comprising a region including neither said polarization separating surfaces nor said reflecting surfaces, said region being made of a transmissive material and disposed on an end opposite to a predetermined space side of each of said two polarization conversion element arrays.

8. An optical element according to claim 4, wherein said polarization separating surfaces and said reflecting surfaces of each of said polarization conversion element arrays are arranged along a direction of arrangement at a pitch that is greater than 1/2 an arrangement pitch of said lens array disposed along the direction of arrangement of said polarization separating surfaces and said reflecting surfaces.

9. A polarization illumination device comprising:

a light source; and

an optical element for converting light from said light source into one type of polarized light,

wherein said optical element includes a lens array composed of a plurality of lenses disposed in a matrix; and

two polarization conversion element arrays, affixed to one surface of said lens array, for converting polarized light with random polarization directions to one type of polarized light,

wherein each of said two polarization conversion element arrays includes polarization separating surfaces for separating the polarized light with random polarization directions into two types of linearly polarized light and reflecting surfaces for reflecting one of the two types of the linearly polarized light produced by separation by said polarization separating surfaces, said polarization separating surfaces and said reflecting surfaces being alternately arranged between light-transmissive members, and

wherein said two polarization conversion element arrays are separated by a predetermined space with no elements disposed between the two polarization conversion element arrays, said polarization separating surfaces of one of said two polarization conversion element arrays are arranged opposite to said polarization separating surfaces of the other of said two polarization conversion element arrays with respect to the predetermined space.

10. A polarization illumination device according to claim 9, further comprising a dummy region including neither said polarization separating surfaces nor said reflecting surfaces, said dummy region being made of a transmissive material and disposed on an end at a predetermined space side of each of said two polarization conversion element arrays.

11. A polarization illumination device according to claim 10, wherein a corner at the predetermined space side of said dummy region is removed.

12. A polarization illumination device according to claim 9, further comprising a region including neither said polarization separating surfaces nor said reflecting surfaces, said region being made of a transmissive material and disposed on an end opposite to a predetermined space side of each of said two polarization conversion element arrays.

13. A polarization illumination device according to claim 9, wherein said polarization separating surfaces are arranged in accordance with a distribution of light leaving said lens array.

14. A polarization illumination device according to claim 9, further comprising a polarization separating surface disposed at a location closest to the predetermined space between said two polarization conversion element arrays, such that a center of said closest polarization separating surface is disposed closer towards the predetermined space than a center axis of a lens among said plurality of lenses of said lens array which is disposed closest to said closest polarization separating surface.

15. A polarization illumination device according to claim 9, wherein said polarization separating surfaces and said reflecting surfaces of each of said polarization conversion element arrays are arranged along a direction of arrangement at a pitch that is greater than 1/2 an arrangement pitch of said lens array disposed along the direction of arrangement of said polarization separating surfaces and said reflecting surfaces.

16. A projection display apparatus comprising:

a polarization illumination device;

modulating means for modulating light from said polarization illumination device in accordance with a received image signal; and

projection optical means for projecting the light beam modulated by said modulating means,

wherein said polarization illumination device includes a light source; and

an optical element for converting light from said light source incident thereupon to light with a predetermined polarization direction that leaves said optical element, and

wherein said optical element includes a lens array composed of a plurality of lenses disposed in a matrix; and

two polarization conversion element arrays, affixed to one surface of said lens array, for converting polarized light with random polarization directions to one type of polarized light,

wherein each of said two polarization conversion element arrays includes polarization separating surfaces for separating the polarized light with random polarization directions into two types of linearly polarized light and reflecting surfaces for reflecting one of the two types of the linearly polarized light produced by separation by said polarization separating surfaces, said polarization separating surfaces and said reflecting surfaces being alternately arranged between light-transmissive members, and

wherein said two polarization conversion element arrays are separated by a predetermined space with no elements disposed between the two polarization conversion element arrays, said polarization separating surfaces of one of said two polarization conversion element arrays are arranged opposite to said polarization separating surfaces of the other of said two polarization conversion element arrays with respect to the predetermined space.

17. A projection display apparatus according to claim 16, further comprising a dummy region including neither said polarization separating surfaces nor said reflecting surfaces, said dummy region being made of a transmissive material and disposed on an end at a predetermined space side of each of said two polarization conversion element arrays.

18. A projection display apparatus according to claim 17, wherein a corner at the predetermined space side of said dummy region is removed.

19. A projection display apparatus according to claim 16, further comprising a region including neither said polarization separating surfaces nor said reflecting surfaces, said region being made of a transmissive material and disposed on an end opposite to a predetermined space side of each of said two polarization conversion element arrays.

20. A projection display apparatus according to claim 16, wherein said polarization separating surfaces are arranged in accordance with a distribution of light leaving said lens array.

21. A projection display apparatus according to claim 16, further comprising a polarization separating surface disposed at a location closest to the predetermined space between said two polarization conversion element arrays, such that a center of said closest polarization separating surface is disposed closer towards the predetermined space than a center axis of a lens among said plurality of lenses of said lens array which is disposed closest to said closest polarization separating surface.

22. A projection display apparatus according to claim 16, wherein said polarization separating surfaces and said reflecting surfaces along the light-incoming surface of each of said polarization conversion element arrays are arranged along a direction of arrangement at a pitch that is greater than 1/2 an arrangement pitch of said lens array disposed along the direction of arrangement of said polarization separating surfaces and said reflecting surfaces.