Projection type image display apparatus

• US 6,183,090 B1
• Filed: 06/17/1998
• Issued: 02/06/2001
• Est. Priority Date: 06/20/1997
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Nakanishi, Hiroshi, Takahara, Ikuo, Hamada, Hiroshi, Kato, Hiromi
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US09/098,455
• Time in Patent Office: 965 Days
• Field of Search: 353/34, 353/33, 353/20, 353/30, 353/31, 359/483, 359/487, 359/488, 359/495, 359/500
• US Class Current: 353/20
• CPC Class Codes: G02B 27/1026 for use with reflective spatial light modulators
• CPC Class Codes: G02B 27/1046 for use with transmissive spatial light modulators
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• 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

A projection type image display apparatus of the present invention includes: a light source; a polarization selective reflection element having a function of reflecting or transmitting a light beam from the light source in accordance with a polarization direction thereof; and an element for modulating a polarization plane of an incident light beam in accordance with an image to be displayed. The polarization selective reflection element is film-like and has an optical transmission axis and an optical reflection axis. The polarization selective reflection element transmits a first linearly polarized light beam, and reflects a second linearly polarized light beam having a polarization plane orthogonal to a polarization plane of the first linearly polarized light beam, regardless of a direction of incidence of a light beam with respect to the polarization selective reflection element.

Claims

1. A projection type image display apparatus, comprising:

a light source;

a first polarization selective reflection element having a function of reflecting or transmitting a light beam from the light source in accordance with a polarization direction thereof;

a first element for modulating a polarization plane of an incident light beam in accordance with an image to be displayed;

a projection lens for projecting the modulated light beam; and

a polarizing filter for transmitting only a linearly polarized component of a light beam having one direction, said polarizing filter being located between at least one of the light source and the first polarization selective reflection element, and the first polarization selective reflection element and the protection lens,

wherein the first polarization selective reflection element is film-like and has an optical transmission axis and an optical reflection axis,

the first polarization selective reflection element transmits a first linearly polarized light beam, and reflects a second linearly polarized light beam having a polarization plane orthogonal to a polarization plane of the first linearly polarized light beam, regardless of a direction of incidence of a light beam with respect to the first polarization selective reflection element,

the first polarization selective reflection element has a structure in which a polarization selective reflection film having a polarization selective reflection function is stacked on a polarizing filter for transmitting only a linearly polarized component of a light beam having one direction, the polarization selective reflection film being closer to the first element.

2. A projection type image display apparatus, comprising:

a light source;

a

first polarization selective reflection element having a function of reflecting or transmitting a light beam from the light source in accordance with a polarization direction thereof;

a first element for modulating a polarization plane of an incident light beam in accordance with an image to be displayed;

a projection lens for projecting the modulated light beam; and

polarizing filters for transmitting only a linearly polarized component of a light beam having one direction,

wherein the polarization selective reflection element is film-like and has an optical transmission axis and an optical reflection axis,

the polarization selective reflection element transmits a first linearly polarized light beam, and reflects a second linearly polarized light beam having a polarization plane orthogonal to a polarization plane of the first linearly polarized light beam, regardless of a direction of incidence of a light beam with respect to the polarization selective reflection element, and

the polarizing filters including a first polarizing filter located between the light source and the polarization selective reflection element, and a second polarizing filter located between the polarization selective reflection element and the projection lens, the first and second polarizing filters being arranged in such a manner that the transmission axes thereof are in a crossed Nicols state with respect to the optical path.

3. A projection type image display apparatus according to claim 2, wherein

the first element for modulating the polarization plane of an incident light beam is a reflective image display element,

the reflective image display element receives the reflected or transmitted light beam from the first polarization selective reflection element,

the light beam reflected by the reflective image display element is a modulated light beam which is incident upon the first polarization selective reflection element, and

the modulated light beam is transmitted or reflected by the first polarization selective reflection element and is incident upon the projection lens.

4. A projection type image display apparatus according to claim 2, wherein the polarization selective reflection element has a structure in which, a polarization selective reflection film having a polarization selective reflection function is stacked on a polarizing filter for transmitting only a linearly polarized component of a light beam having one direction, the polarization selective reflection film being closer to the first element.

5. A projection type image display apparatus according to claim 2, further comprising:

a color separating element for separating a light beam from the light source into a plurality of light beams each having a different wavelength region;

a plurality of polarization selective reflection elements having a function of reflecting or transmitting a light beam from the light source in accordance with a polarization direction thereof the plurality of polarization selective reflection elements including the first polarization selective reflective element;

a plurality of elements for modulating a polarization plane of an incident light beam in accordance with an image to be displayed, the plurality of elements including the first element; and

a color synthesizing element for synthesizing the plurality of light beams each having a different wavelength region, and

wherein the plurality of polarization selective reflection elements and the plurality of reflective image display elements respectively correspond to the plurality of light beams each having a different wavelength region,

the color separating element is provided in an optical path between the plurality of polarization selective reflection elements and the light source, and

the color synthesizing element is provided in an optical path between the plurality of polarization selective reflection elements and the projection lens.

6. A projection type image display apparatus according to claim 2, wherein:

the first element is one of a plurality of elements,

the apparatus further comprises in addition to the first polarization selective reflection element, a second polarization selective reflection element between the projection lens and the plurality of elements,

light beams which have been reflected or transmitted by the first polarization selective reflection element and which have been modulated by the plurality of elements are synthesized by the second polarization selective reflection element to form a synthesized light beam, the light beams reflected or transmitted by the first polarization selective reflection element corresponding to the plurality of image display elements, respectively, and

the synthesized light beam is incident upon the projection lens.

7. A projection type image display apparatus according to claim 2, further comprising a color separating element and a color synthesizing element wherein:

the first element comprises one of a plurality of reflective image display elements,

the color separating element separates a light beam from the light source into a plurality of light beams each having a different wavelength region,

the plurality of reflective image display elements respectively correspond to the plurality of light beams each having a different wavelength region,

the color synthesizing element synthesizes the plurality of light beams each having a different wavelength region reflected by the plurality of reflective image display elements,

the first polarization selective reflection element corresponds to the synthesized light beam having the different wavelength regions, and

a single element is commonly used as the color separating element and the color synthesizing element.

8. A projection type image display apparatus according to claim 2, wherein the first linearly polarized light beam is parallel to the transmission axis and the second linearly polarized light beam is parallel to the reflection axis.

9. A projection type image display apparatus, comprising:

a light source;

a polarization selective reflection element for transmitting light from said light source of one polarization and reflecting light from said light source of another polarization, said polarization selective reflection element transmitting the light having the one polarization as a first linearly polarized light beam parallel to a transmission axis thereof and reflecting the light having the other polarization as a second linearly polarized light beam parallel to a reflection axis thereof;

a light modulating element for modulating a polarization of one of the first and second linearly polarized light beams in accordance with an image to be displayed;

a projection lens for projecting the modulated light beam; and

polarizing filters for transmitting only a linearly polarized component of a light beam having one direction, the polarizing filters including a first polarizing filter located between the light source and the polarization selective reflection element, and a second polarizing filter located between the polarization selective reflection element and the projection lens, the first and second polarizing filters being arranged in such a manner that the transmission axes thereof are in a crossed Nicols state with respect to the optical path.

10. A projection type image display apparatus according to claim 9, further comprising:

a wavelength selecting element arranged in the light path between said polarization selective reflection element and said light modulating element for selecting light having a wavelength in a particular wavelength range from the one of the first and second linearly polarized light beams, whereby the selected light is modulated by said light modulating element.

11. A projection type image display apparatus according to claim 9, further comprising:

a wavelength selecting element arranged in the light path between said light source and said polarization selective reflection element for selecting light having a wavelength in a particular wavelength range from the light output by said light source, whereby the selected light is supplied to said polarization selective reflection element.

12. A projection type image display apparatus according to claim 9, wherein said polarization selective reflection element is arranged in the light path between said light modulating element and said projection lens.

13. A projection type image display apparatus according to claim 9, wherein said polarization selective reflection element comprises a polarization selective reflection film.

14. A projection type image display apparatus, comprising:

a light source;

a plurality of a polarization selective reflection elements each for transmitting light from said light source of one polarization and reflecting light from said light source of another polarization, each said polarization selective reflection element transmitting the light having the one polarization as a first linearly polarized light beam parallel to a transmission axis thereof and reflecting the light having the other polarization as a second linearly polarized light beam parallel to a reflection axis thereof;

light modulating elements, each light modulating element modulating a polarization plane of one of the first and second linearly polarized light beams of a corresponding one of said polarization selective reflection elements in accordance with an image to be displayed;

a synthesizing element for synthesizing the light beams modulated by said light modulating elements;

a projection lens for projecting the synthesized modulated light, and polarizing filters arranged in the light paths between said light source and each of said polarization selective reflection elements.

15. A projection type image display apparatus according to claim 14, wherein each of said polarization selective reflection elements comprises a polarization selective reflection film.

16. A projection type image display apparatus according to claim 14, wherein the light paths to each of the light modulating elements have substantially the same length in air equivalent.

17. A projection type image display apparatus, comprising:

a light source;

a plurality of a polarization selective reflection elements each for transmitting light from said light source of one polarization and reflecting light from said light source of another polarization, each said polarization selective reflection element transmitting the light having the one polarization as a first linearly polarized light beam parallel to a transmission axis thereof and reflecting the light having the other polarization as a second linearly polarized light beam parallel to a reflection axis thereof;

light modulating elements, each light modulating element modulating a polarization plane of one of the first and second linearly polarized light beams of a corresponding one of said polarization selective reflection elements in accordance with an image to be displayed;

a synthesizing element for synthesizing the light beams modulated by said light modulating elements;

a projection lens for projecting the synthesized modulated light; and

polarizing filters for transmitting only a linearly polarized component of a light beam having one direction, the polarizing filters including first polarizing filters each of which is located between the light source and one of the polarization selective reflection elements, and second polarizing filters each of which is located between one of the polarization selective reflection elements and the projection lens, the first and second polarizing filters being arranged in such a manner that the transmission axes of respective pairs of first and second polarizing filters are in a crossed Nicols state with respect to the optical path.

19. A projection type image display apparatus according to claim 17, wherein the light paths to each of the light modulating elements have substantially the same length in air equivalent.

20. A projection type image display apparatus according to claim 17, wherein each of said polarization selective reflection elements comprises a polarization selective reflection film.

18. A projection type image display apparatus, comprising:

a light source;

a first polarization selective reflection element having a function of reflecting or transmitting a light beam from the light source in accordance with a polarization direction thereof;

a first element for modulating a polarization plane of an incident light beam in accordance with an image to be displayed; and

a projection lens for projecting the modulated light beam,

wherein the first polarization selective reflection element is film-like and has an optical transmission axis and an optical reflection axis,

the first polarization selective reflection element transmits a first linearly polarized light beam, and reflects a second linearly polarized light beam having a polarization plane orthogonal to a polarization plane of the first linearly polarized light beam, regardless of a direction of incidence of a light beam with respect to the first polarization selective reflection element, wherein

the first element is one of a plurality of elements,

the apparatus further comprises in addition to the first polarization selective reflection element, a second polarization selective reflection element between the projection lens and the plurality of elements,

light beams which have been reflected or transmitted by the first polarization selective reflection element and which have been modulated by the plurality of elements are synthesized by the second polarization selective reflection element to form a synthesized light beam, the light beams reflected or transmitted by the first polarization selective reflection element corresponding to the plurality of image display elements, respectively, and

the synthesized light beam is incident upon the projection lens.