Image display apparatus and optical system

• US 20020021498A1
• Filed: 04/26/2001
• Published: 02/21/2002
• Est. Priority Date: 04/28/2000
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Sudo, Takashi, Ohtaka, Keiji
• Granted Patent: US 6,594,085 B2
• Time in Patent Office: Days
• US Class Current: 359/629
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00

Abstract

An image display apparatus includes a light source for supplying illumination light, a reflection type display element for modulating the illumination light into image light by reflecting the light, an illumination optical system for guiding the illumination light to the reflection type display element, and a projection optical system for guiding the image light to an observer. The image light is incident on the projection optical system via at least a portion of the illumination optical system. The illumination optical system has a part, in an area where both the illumination light and the image light pass, which changes an optical action depending on a state of incident light. The part acts to deflect the illumination light to decrease an incident angle with respect to the reflection type display element as compared with a case where the part does not exist.

Claims

1. An image display apparatus comprising:

a light source for supplying illumination light;

a reflection type display element for modulating the illumination light into image light by reflecting illumination;

an illumination optical system for guiding the illumination light to said reflection type display element; and

a projection optical system for guiding the image light to an observer,

wherein the image light is incident on said projection optical system via at least a portion of said illumination optical system, and

said illumination optical system has a part, in an area where both the illumination light and the image light pass, which changes an optical action depending on a state of incident light, said part deflecting the illumination light to decrease an incident angle with respect to said reflection type display element as compared with a case where the part does not exist.

2. An apparatus according to claim 1, wherein the optical action exerted on the illumination light and the image light by said part changes depending on an incident angle of incident light.

3. An apparatus according to claim 1, wherein said part comprises a diffraction optical part whose diffraction effect changes depending on the incident angle of incident light.

4. An apparatus according to claim 1, wherein the optical action exerted on the illumination light and the image light by said part changes depending on a polarized state of incident light.

5. An apparatus according to claim 1, wherein said part comprises a diffraction optical part whose diffraction effect changes depending on the polarized state of incident light.

6. An apparatus according to claim 1, wherein letting θ

1 be the incident angle of the illumination light on said part, and θ

2 be the incident angle of the image light, a condition given by

|θ

1|>

|θ

2|

is satisfied.

7. An apparatus according to claim 1, wherein said part comprises a diffraction optical part which is placed in front of said reflection type display element and changes an optical action depending on a state of incident light, and letting θ

1 be the incident angle of the illumination light on said diffraction optical part and β

be the incident angle of the illumination light on said reflection type display element, a condition given by

|θ

1|>

|β

|

is satisfied.

8. An apparatus according to claim 1, wherein said part comprises a reflection/diffraction optical part whose optical action changes depending on a state of incident light, and letting θ

3 be the incident angle of the illumination light on said reflection/diffraction optical part and θ

4 be the reflection angle of the illumination light which is subjected to the reflection/diffraction effect of said reflection/diffraction optical part and propagates to said reflection type display element, a condition given by

|θ

3|>

|θ

4|

is satisfied.

9. An apparatus according to claim 1, wherein said illumination optical system comprises an optical member having a first surface on which the illumination light is incident, a second surface by which light incident from the first surface is totally reflected, and a third surface from which the light totally reflected by the second surface emerges toward said reflection type display element, and image light modulated by said reflection type display element enters said optical member through the third surface again and emerges from the second surface toward said projection optical system.

10. An apparatus according to claim 9, further comprising:

a reflection type liquid crystal display element serving as said reflection type image display element;

a first polarizing member for converting the illumination light into S-polarized light and making the light strike said optical member; and

a second polarizing member for analyzing image light modulated into P-polarized light by said reflection type liquid crystal display element.

11. An apparatus according to claim 1, wherein said projection optical system comprises an optical element having a plurality of optical acting surfaces, at least one of the plurality of optical acting surfaces is a reflecting surface, and at least one of the optical acting surfaces is a rotationally asymmetric surface.

13. An apparatus according to claim 12, wherein an optical action exerted on the illumination light and the image light by said diffraction optical part changes depending on an incident angle of incident light.

14. An apparatus according to claim 12, wherein an optical action exerted on the illumination light and the image light by said diffraction optical part changes depending on a polarized state of incident light.

15. An apparatus according to claim 12, wherein letting θ

1 be the incident angle of the illumination light on said diffraction optical part, and θ

2 be the incident angle of the image light, a condition given by

|θ

1|>

|θ

2|

is satisfied.

16. An apparatus according to claim 12, wherein said diffraction optical part comprises a diffraction optical part placed in front of said reflection type display element, and letting θ

1 be the incident angle of the illumination light on said diffraction optical part and β

be the incident angle of the illumination light on said reflection type display element, a condition given by

|θ

1|>

|β

|

is satisfied.

17. An apparatus according to claim 12, wherein said diffraction optical part comprises a reflection/diffraction optical part whose optical action changes depending on a state of incident light, and letting θ

3 be the incident angle of the illumination light on said reflection/diffraction optical part and θ

4 be the reflection angle of the illumination light which is subjected to the reflection/diffraction effect of said reflection/diffraction optical part and propagates to said reflection type display element, a condition given by

|θ

3|>

|θ

4|

is satisfied.

18. An apparatus according to claim 12, wherein said illumination optical system comprises an optical member having a first surface on which the illumination light is incident, a second surface by which light incident from the first surface is totally reflected, and a third surface from which the light totally reflected by the second surface emerges toward said reflection type display element, and image light modulated by said reflection type display element enters said optical member through the third surface again and emerges from the second surface toward said projection optical system.

19. An apparatus according to claim 18, further comprising:

a reflection type liquid crystal display element serving as said reflection type image display element;

a first polarizing member for converting the illumination light into S-polarized light and making the light strike said optical member; and

a second polarizing member for analyzing image light modulated into P-polarized light by said reflection type liquid crystal display element.

20. An apparatus according to claim 12, wherein said projection optical system comprises an optical element having a plurality of optical acting surfaces, at least one of the plurality of optical acting surfaces is a reflecting surface, and at least one of the optical acting surfaces is a rotationally asymmetric surface.

21. An image display system comprising:

said image display apparatus defined in claim 1 or 12; and

an image information output apparatus for supplying image information to said image display apparatus.

12. An image display apparatus comprising:

a light source for supplying illumination light;

a reflection type display element for modulating the illumination light into image light by reflecting illumination;

an illumination optical system for guiding the illumination light to said reflection type display element; and

a projection optical system for guiding the image light to an observer,

wherein the image light is incident on said projection optical system via at least a portion of said illumination optical system, and

said illumination optical system has a diffraction optical part in an area where both the illumination light and the image light pass.

22. An optical system comprising:

an illumination optical system for guiding illumination light to a reflection type display element; and

a projection optical system for guiding image light reflected by the reflection type display element to an observer,

wherein the image light is incident on said projection optical system via at least a portion of said illumination optical system, and

said illumination optical system has a part, in an area where both the illumination light and the image light pass, which changes an optical action depending on a state of incident light, said part deflecting the illumination light to decrease an incident angle with respect to said reflection type display element as compared with a case where the part does not exist.

23. An optical system comprising:

an illumination optical system for guiding illumination light to a reflection type display element; and

a projection optical system for guiding image light reflected by the reflection type display element to an observer,

wherein the image light is incident on said projection optical system via at least a portion of said illumination optical system, and

said illumination optical system has a diffraction optical part in an area where both the illumination light and the image light pass.