Polarizing illumination device and projection display device

• US 6,084,714 A
• Filed: 01/25/1999
• Issued: 07/04/2000
• Est. Priority Date: 02/16/1998
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Yajima, Akitaka, Ushiyama, Tomiyoshi
• Primary Examiner(s): MACK, RICKY LEVERN
• Application Number:
  US09/236,467
• Time in Patent Office: 526 Days
• Field of Search: 359/619, 359/620, 359/621, 359/622, 359/627, 359/629, 359/487, 359/497, 349/9, 353/20
• US Class Current: 359/627
• 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

Abstract

A technique for preventing a decrease in the amount of effective polarized light that emerges from a polarizing conversion element array is provided. To this end, a polarizing illumination device includes a polarizing conversion element array that converts light emitted from a light source into one type of linearly polarized light, and a plurality of light-shielding portions for blocking a part of light that is incident on the polarizing conversion element array. The polarizing conversion element array is divided into effective incident areas for emitting effective polarized light, and ineffective incident areas for emitting ineffective polarized light. The widths of the plurality of light-shielding portions are set to be smaller than the width of the ineffective incident areas of the polarizing conversion element array, so that light to be incident on the effective incident areas is not blocked. This makes it possible to prevent a decrease in the amount of effective polarized light that emerges from the polarizing conversion element array.

Claims

1. A polarizing illumination device that generates one type of polarized light, comprising:

a) a light source;

b) a polarizing conversion element array that converts light emitted from said light source into a first type of linearly polarized light; and

c) a plurality of light-shielding portions that blocks a part of light that is incident on the light incident surface of said polarizing conversion element array,

said polarizing conversion element array comprising;

1) a polarization beam splitter array having a light separating surface that separates the light from said light source into the first type of linearly polarized light and a second type of linearly polarized lights, and

2) a selective phase plate selectively disposed on a light emitting surface of said polarization beam splitter array to convert the second type of linearly polarized light into the first type of linearly polarized light,

said polarization beam splitter array having a plurality of polarization separating films and a plurality of reflecting films alternately arranged along a predetermined direction with an arrangement space there between,

said plurality of light-shielding portions being arranged nearly in parallel with the predetermined direction and having set widths, and

the widths of said plurality of light-shielding portions along the predetermined direction being smaller than the arrangement space between said polarization separating films and said reflecting films along the predetermined direction.

2. A polarizing illumination device according to claim 1, said polarizing conversion element array having a center and said plurality of light-shielding portions being arranged so that distances therebetween increase from the center of said polarizing conversion element array.

3. A polarizing illumination device according to claim 1, said polarizing conversion element array having a center and said plurality light-shielding portions are arranged so that distances therebetween decrease from the center of said polarizing conversion element array.

4. A polarizing illumination device according to claim 1, said polarizing conversion element array having a center and the widths of said plurality of light-shielding portions being set to decrease from the center of said polarizing conversion element array.

5. A projection display device that projects an image, said projection display comprising:

a) a polarizing illumination device that generates one type of polarized light;

b) a modulation device that modulates emitting light from said polarizing illumination device according to a given image signal; and

c) a projection optical device that projects the light modulated by said modulation device,

said polarizing illumination device comprising;

1) a light source;

2) a polarizing conversion element array that converts light emitted from said light source into a first type of linearly polarized light; and

3) a plurality of light-shielding portions that block a part of light that is incident on the light incident surface of said polarizing conversion element array,

said polarizing conversion element array comprising;

a polarization beam splitter array having a light separating surface that separates the light from said light source into the first type of linearly polarized light and a second type of linearly polarized light; and

a selective phase plate selectively disposed on a light emitting surface of said polarization beam splitter array to convert the second type of linearly polarized light into the first type of linearly polarized light,

said polarization beam splitter array having a plurality of polarization separating films and a plurality of reflecting films alternately arranged along a predetermined direction with an arrangement space therebetween,

said plurality of light-shielding portions being arranged nearly in parallel with the predetermined direction and having set widths, and

the widths of said plurality of light-shielding portions along the predetermined direction being smaller than the arrangement space between said polarization separating films and said reflecting films along the predetermined direction.

6. A projection display device according to claim 5, said polarizing conversion element array having a center and said plurality of light-shielding portions having selective distances therebetween, said plurality of light-shielding portions being arranged so that the distances therebetween increase from the center of said polarizing conversion element array.

7. A projection display device according to claim 5, said polarizing conversion element array having a center and said plurality of light-shielding portions having selective distances therebetween, said plurality of light-shielding portions being arranged so that the distances therebetween decrease from the center of said polarizing conversion element array.

8. A projection display device according to claim 5, said polarizing conversion element array having a center and the widths of said plurality of light-shielding portions being set to decrease from the center of said polarizing conversion element array.