Illumination apparatus and image projection apparatus using the illumination apparatus

• US 20070091271A1
• Filed: 12/13/2006
• Published: 04/26/2007
• Est. Priority Date: 09/12/2002
• Status: Active Grant

• Current Assignee: Olympus Corporation
• Original Assignee: Olympus Corporation
• Inventors: Hanano, Kazunari
• Granted Patent: US 7,350,924 B2
• Time in Patent Office: Days
• US Class Current: 353/30
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0955 Lenses lenses per se G02B3/00
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/2066 Reflectors in illumination beam in projection beam G03B21/28
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

An illumination apparatus comprises a small-plane light source having diffusion radiation characteristics, a columnar light leading member, having an incident end surface, an outgoing radiation end surface and a reflection surface, configured to reflect on the reflection surface, at least a part of a light ray from small-plane light source collected from the incident end surface, thereby leading the light to the outgoing radiation end surface, and an angle position converting member configured to convert an outgoing light angle intensity of the outgoing light from the outgoing radiation end surface of the columnar light leading member into a position intensity in a predetermined irradiation area.

Claims

1. An illumination apparatus comprising:

a small-plane light source having diffusion radiation characteristics;

a columnar light leading member, having an incident end surface, an outgoing radiation end surface and a reflection surface, configured to reflect on the reflection surface at least a part of a light ray from the small-plane light source collected from the incident end surface, thereby leading the light to the outgoing radiation end surface; and

an angle position converting member configured to convert an outgoing light angle intensity of the outgoing light from the outgoing radiation end surface of the columnar light leading member into a position intensity in a predetermined irradiation area, wherein a distance between the angle position converting member and the predetermined irradiation area is substantially equal to a focal distance of the angle position converting member;

the angle position converting member including a pupil forming member configured to form a pupil by using the outgoing radiation end surface of the columnar light leading member as a virtual light source,

a position of the irradiation area is set in the vicinity of a position of a pupil formed by the pupil forming member; and

a light diffusion element arranged on a rear stage of the outgoing radiation end surface of the columnar light leading member.

2. The apparatus according to claim 1, wherein, when the pupil forming member has a focal distance f and a size of the irradiation area is L, a diffusion angle θ

of the light diffusion element satisfies the following expression;

−

2×

Tan<sup>−

1</sup> (0.5×

L/f)<

θ

<

2×

Tan<sup>−

1</sup> (0.5×

L/f)

3. The apparatus according to claim 1, wherein the light diffusion element includes a one-dimensional diffuser.

4. An illumination apparatus comprising:

a small-plane light source having diffusion radiation characteristics;

a columnar light leading member, having an incident end surface, an outgoing radiation end surface and a reflection surface, configured to reflect on the reflection surface at least a part of a light ray from the small-plane light source collected from the incident end surface, thereby leading the light to the outgoing radiation end surface; and

an angle position converting member configured to convert an outgoing light angle intensity of the outgoing light from the outgoing radiation end surface of the columnar light leading member into a position intensity in a predetermined irradiation area, wherein a distance between the angle position converting member and the predetermined irradiation area is substantially equal to a focal distance of the angle position converting member; and

wherein the pupil forming member is arranged so as to be eccentric with respect to a normal line of the outgoing radiation end surface of the columnar light leading member.

5. The apparatus according to claim 4, wherein the pupil forming member includes a prism having free-form surfaces.

6. An image projection apparatus comprising:

an illumination apparatus comprising;

a small-plane light source having diffusion radiation characteristics;

a columnar light leading member, having an incident end surface, an outgoing radiation end surface and a reflection surface, configured to reflect on the reflection surface at least a part of a light ray from the small-plane light source collected from the incident end surface, thereby leading the light to the outgoing radiation end surface; and

an angle position converting member configured to convert an outgoing light angle intensity of the outgoing light from the outgoing radiation end surface of the columnar light leading member into a position intensity in a predetermined irradiation area;

a light modulation element, having a pixel structure, configured to modulate a light ray for each pixel in accordance with an image signal; and

a projection lens configured to enlarge and project the light modulation element, wherein

the light modulation element is arranged in the illumination area in the illumination apparatus and the distance between the outgoing radiation end surface and the angle position converting member and the distance between the angle position converting member and the light modulation element are substantially equal;

the angle position converting member including a pupil forming member configured to form a pupil by using the outgoing radiation end surface of the columnar light leading member as a virtual light source, and

a position of the irradiation area is set in the vicinity of a position of a pupil formed by the pupil forming member; and

further comprising a light diffusion element arranged on a rear stage of the outgoing radiation end surface of the columnar light leading member.

7. The apparatus according to claim 6, wherein, when the pupil forming member has a focal distance f and a size of the irradiation area is L, a diffusion angle θ

of the light diffusion element satisfies the following expression;

−

2×

Tan<sup>−

1</sup> (0.5×

L/f)<

θ

<

2×

Tan<sup>−

1</sup> (0.5×

L/f)

8. The apparatus according to claim 6, wherein the light diffusion element includes a one-dimensional diffuser.

9. An image projection apparatus comprising:

an illumination apparatus comprising;

a small-plane light source having diffusion radiation characteristics;

a columnar light leading member, having an incident end surface, an outgoing radiation end surface and a reflection surface, configured to reflect on the reflection surface at least a part of a light ray from the small-plane light source collected from the incident end surface, thereby leading the light to the outgoing radiation end surface; and

an angle position converting member configured to convert an outgoing light angle intensity of the outgoing light from the outgoing radiation end surface of the columnar light leading member into a position intensity in a predetermined irradiation area;

a light modulation element, having a pixel structure, configured to modulate a light ray for each pixel in accordance with an image signal; and

a projection lens configured to enlarge and project the light modulation element, wherein

the light modulation element is arranged in the illumination area in the illumination apparatus and the distance between the outgoing radiation end surface and the angle position converting member and the distance between the angle position converting member and the light modulation element are substantially equal;

the angle position converting member including a pupil forming member configured to form a pupil by using the outgoing radiation end surface of the columnar light leading member as a virtual light source, and

wherein the pupil forming member is arranged so as to be eccentric with respect to a normal line of the outgoing radiation end surface of the columnar light leading member.

10. The apparatus according to claim 9, wherein the pupil forming member includes a prism having free-form surfaces.