Illuminating device and projector utilizing the same

• US 5,692,819 A
• Filed: 03/02/1995
• Issued: 12/02/1997
• Est. Priority Date: 10/21/1991
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Shingaki, Junko, Kimura, Kazumi, Mitsutake, Hideaki, Kawasaki, Shigeru, Yano, Kohtaro
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US08/403,549
• Time in Patent Office: 1,006 Days
• Field of Search: 353/31, 353/33, 353/34, 353/37, 353/38, 353/98, 353/99, 353/102, 353/97, 353/122, 353/101, 359/40, 359/49, 359/48, 362/268, 362/296, 362/307, 362/308, 362/311, 352/297, 352/261, 352/263
• US Class Current: 353/31
• CPC Class Codes: F21V 7/09 with a combination of different curvatures
• CPC Class Codes: F21W 2131/406 for theatres, stages or film studios
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09

Abstract

A projector comprising a light source having first and second high-luminance light emitting areas, an illuminating optical system for directing the light, from said light source, toward an object to be illuminated, wherein said first and second high-luminance light-emitting areas are positioned on the optical axis of said illuminating optical system, and a projection optical system for projecting the light emerging from said illuminated object, wherein said illuminating optical system is constructed in such a manner that a central area of said illuminated object is illuminated by most of the light beam from said first high-luminance light-emitting area, and a peripheral area of said illuminated object is illuminated by the remainder of the light beam from said first high-luminance light emitting area and most of the light from said second high-luminance light-emitting area.

Claims

1. A projector comprising:

a light source having first and second high-luminance light emitting areas;

an illuminating optical system for directing light, from said light source, toward an object to be illuminated, wherein said first and second high-luminance light-emitting areas are positioned on an optical axis of said illuminating optical system; and

a projection optical system for projecting the light emerging from said illuminated object;

wherein said illuminating optical system is constructed in such a manner that multiple rays of light emitted from a point in said first high-luminance light-emitting area are imaged on a central area of said illuminated object such that said multiple rays of light converge at one point in said central area and that multiple rays of light emitted from respective points in each of said first and second high-luminance light-emitting areas are imaged on a peripheral area of said illuminated object such that said multiple rays of light emitted from said respective points in each of said first and second high-luminance light-emitting areas converge at points in said peripheral central area.

2. A projector according to claim 1, wherein said illuminating optical system includes:

a reflector for reflecting the light from said light source; and

a refractive element provided at the peripheral area at the aperture side of said reflector.

3. A projector according to claim 1, wherein said illuminating optical system is constructed in such a manner that said first high-luminance light-emitting area is imaged on the central area of said illuminated object and that said first and second high-luminance light-emitting areas are imaged on the peripheral area of said illuminated object.

4. A projector according to claim 1, wherein said illuminated object is composed of a light valve composed of TN liquid crystal capable of forming an image by modulating the light, and said illuminating optical system includes a polarizing beam splitter for separating the light, prior to the entry into said light valve, into polarized lights of mutually different polarizing directions and directing one of said polarized lights towards said light valve.

5. A projector according to claim 1, wherein said illuminated object is composed of a light valve composed of ferroelectric liquid crystal capable of forming an image by modulating the light, and said illuminating optical system includes a polarizing beam splitter for separating the light, prior to the entry into said light valve, into polarized lights of mutually different polarizing directions and directing one of said polarized lights towards said light valve.

6. A projector according to claim 1, wherein said illuminated object is composed of a light valve composed of PLZT capable of forming an image by modulating the light, and said illuminating optical system includes a polarizing beam splitter for separating the light, prior to the entry into said light valve, into polarized lights of mutually different polarizing directions and directing one of said polarized lights towards said light valve.

7. A projector according to claim 1, wherein said illuminating optical system has a concave mirror whose focusing point is positioned on said optical axis, said concave mirror is provided at the back of said light source, and said focusing point is substantially consistent with the high-luminance light-emitting area positioned nearer to said concave mirror of said two high-luminance light-emitting areas.

8. An illuminating apparatus comprising:

a light source having first and second high-luminance light-emitting areas; and

an illuminating optical system for directing the light from said light source toward an object to be illuminated, wherein said first and second high-luminance light-emitting areas are positioned on the optical axis of said illuminating optical system;

wherein said illuminating optical system is constructed in such a manner that multiple rays of light emitted from a point in said first high-luminance light-emitting area are imaged on a central area of said illuminated object such that said multiple rays of light converge at one point in said central area and that multiple rays of light emitted from respective points in each of said first and second high-luminance light-emitting areas are imaged on a peripheral area of said illuminated object such that said multiple rays of light emitted from said respective points in each of said first and second high-luminance light-emitting areas converge at points in said peripheral area.

9. An illuminating apparatus according to claim 8, wherein said illuminating optical system has a concave mirror whose focusing point is positioned on said optical axis, said concave mirror is provided at the back of said light source, and said focusing point is substantially consistent with the high-luminance light-emitting area positioned nearer to said concave mirror of said two high-luminance light-emitting areas.

10. A projector comprising:

a white light source having first and second high-luminance light-emitting areas;

an illuminating optical system for receiving a white light from said light source, wherein said first and second high-luminance light-emitting areas are positioned on the optical axis of said illuminating optical system;

color separation means for separating said white light into component lights of red, green and blue;

three modulation means for forming image lights respectively corresponding to said component lights of red, green and blue;

color synthesis means for synthesizing said image lights; and

a projection optical system for projecting thus synthesized image lights;

wherein said illuminating optical system is constructed in such a manner that multiple rays of light emitted from a point in said first high-luminance light-emitting area are imaged on a central area of said modulation means such that said multiple rays of light converge at one point in said central area and that multiple rays of light emitted from respective points in each of said first and second high-luminance light-emitting areas are imaged on a peripheral area of said modulation means such that said multiple rays of light emitted from said respective points in each of said first and second high-luminance light-emitting areas converge at points in said peripheral area.

11. A projector according to claim 10, wherein said illuminating optical system has a concave mirror whose focusing point is positioned on said optical axis, said concave mirror is provided at the back of said light source, and said focusing point is substantially consistent with the high-luminance light-emitting area positioned nearer to said concave mirror of said two high-luminance light-emitting areas.

12. A projector comprising:

a light source having first and second high-luminance light-emitting areas;

an illuminating optical system for directing light from said light source toward an object to be illuminated, provided with a reflector of a first focal length, wherein said first and second high-luminance light-emitting areas are positioned on an optical axis of said illuminating optical system;

a projection optical system for projecting the light emerging from said illuminated object; and

an optical element provided in the vicinity of said optical axis and having a second focal length smaller than said first focal length;

wherein said light source, said illuminating optical system and said optical element are positioned in such a manner that light from said first high-luminance light-emitting area, emerging from said reflector, and light from said second high-luminance light-emitting area, emerging from said optical element, illuminate a peripheral area of said illuminated object.

13. A projector according to claim 12, wherein said reflector is an elliptical mirror having a first focal point in said first high-luminance light-emitting area and a second focal point on said illuminated object, and said optical element is a lens of a positive refractive power, positioned adjacent to said elliptical mirror.

14. An projector according to claim 12, wherein said reflector is an elliptical mirror having a first focal point in said first high-luminance light-emitting area and a second focal point on said illuminated object, and said optical element is an elliptical mirror having a focal point in a position between said first and second high-luminance light-emitting areas.

15. An illuminating apparatus comprising:

a light source having first and second high-luminance light-emitting areas;

an illuminating optical system provided with a reflector of a first focal length, for directing light from said light source toward an object to be illuminated, wherein said first and second high-luminance light-emitting areas are positioned on an optical axis of said illuminating optical system; and

an optical element provided in the vicinity of said optical axis and having a second focal length smaller than said first focal length;

wherein said light source, said illuminating optical system and said optical element are positioned in such a manner that light from said first high-luminance light-emitting area, emerging from said reflector, and light from said second high-luminance light-emitting area, emerging from said optical element, illuminate a peripheral area of said illuminated object.

16. A projector comprising:

a white light source having first and second high-luminance light-emitting areas;

an illuminating optical system provided with a reflector of a first focal length for reflecting a white light from said light source, wherein said first and second high-luminance light-emitting areas are positioned on an optical axis of said illuminating optical system;

color separation means for separating said white light into component lights of red, green and blue;

three modulation means for forming image lights respectively corresponding to said component lights of red, green and blue;

color synthesis means for synthesizing said image lights;

a projection optical system for projecting thus synthesized image lights; and

an optical element provided in the vicinity of said optical axis and having a second focal length smaller than said first focal length;

wherein said light source, said illuminating optical system and said optical element are positioned in such a manner that light from said first high-luminance light-emitting area, emerging from said reflector, and light from said second high-luminance light-emitting area, emerging from said optical element, illuminate a peripheral area of said illuminated object.

17. A projector comprising:

a light source;

an illuminating optical system for illuminating an object to be illuminated with light from said light source, wherein said light from said light source includes a plurality of light beams each of which illuminates a corresponding off axis point on said object;

a projection optical system for receiving said plural light beams through said object and for projecting an image of said object, said projection optical system having a plurality of pupils each of which is defined in accordance with a vignetting for the light beam from each off axis points on said object; and

means for controlling an incident angle, to said object, of a ray at a center of gravity of each of said light beams such that the ray at the center of gravity of each light beam is substantially directed to a center of the corresponding pupil of said plural pupils.

18. A projector according to claim 17, wherein said illuminating optical system is provided, behind said light source, with a mirror of a parabolic reflecting face of which focal point is positioned substantially at the light emitting area of said light source, and said incident angle controlling means is adapted to receive the light from said light source, by way of said mirror.

19. A projector according to claim 17, wherein said illuminating optical system includes a mirror of aspherical reflecting face of which the center of curvature is positioned substantially at the light-emitting area of said light source, and a collimating lens system of which focal point is positioned substantially at the light-emitting area of said light source, and said incident angle controlling means is adapted to receive the light from said light source, by way of said miror and said collimating lens system.

20. A projector according to claim 17, wherein said illuminating optical system includes a mirror of an elliptical reflecting face of which the first focal point is positioned substantially at the light-emitting area of said light source, and a collimating lens system of which focal point is positioned substantially at the second focal point of the elliptical reflecting face of said mirror, and said incident angle controlling means is adapted to receive the light from said light source, by way of said mirror and said collimating lens system.

21. A projector according to claim 17, wherein said incident angle controlling means includes an aspherical lens of which curvature is varied between the central and peripheral areas thereof in order to control the incident angle of the ray of center of gravity of each of said light beams into the illuminated object.

22. A projector according to claims 21, wherein said aspherical lens is positioned close to the illuminated object and satisfies a relation:

space="preserve" listing-type="equation">Δ

x/2NA<

e.sub.1 <

f

wherein e₁ is the axial distance between the aspherical face of said aspherical lens and said illuminated object, f is the focal length of said aspherical lens, NA is the numerical aperture of said projection optical system at the side of said illuminated object, and Δ

x is the alignment error between the center of said illuminated object and that of said aspherical lens.

23. A projector according to claim 21, wherein said aspherical lens has an aspherical face at the side of said light source, and a spherical face at the side of said illuminated object.

24. A projector according to claim 21, wherein said incident angle controlling means includes aspherical lens between said aspherical lens and said illuminated object.

25. A projector according to claim 17, wherein said incident angle controlling means includes a lens of distributed refractive index, of which refractive index is varied between the central and peripheral areas thereof, in order to control the incident angle of the ray of center of gravity in each of said light beams into the illuminated object.

26. A projector according to claim 25, wherein said lens of distributed refractive index has mutually parallel faces at the side of said light source and at the side of said illuminated object.

27. A projector according to claims 17, wherein said illuminated object includes a liquid crystal device for displaying an image in response to an input signal.

29. A projector according to claim 17, wherein said illuminating optical system is provided, behind said light source, with a mirror of a spherical reflecting face of which focal point is positioned substantially at the light emitting area of said light source, and said incident angle controlling means is adapted to receive the light from said light source, by way of said mirror.

28. A projector comprising:

a white light source;

color separation means for separating a white light from said white light source into component lights of red, green and blue;

three modulating means for forming image lights respectively corresponding to said component lights of red, green and blue, wherein each of said component lights includes a plurality of light beams each of which illuminates a corresponding off axis point on said modulating means;

color synthesis means for synthesizing said image lights of red, green and blue;

a projection optical system for receiving thus synthesized image lights of red, green and blue, each of which includes said plural light beams illuminating the off axis points on said modulating means, said projection optical system having a plurality of pupils each of which is defined in accordance with a vignetting for the light beams from each off axis points on said modulating means; and

means for controlling an incident angle, to said modulating means of a ray at a center of gravity of each of said light beams such that the ray at the center of gravity of each light beams is directed to a center of corresponding pupil of said plural pupils.

30. A projector comprising:

a light source having first and second high-luminance light-emitting areas;

an illuminating optical system for directing light, from said light source, toward an object to be illuminated, wherein said first and second high-luminance light-emitting areas are positioned on an optical axis of said illuminating optical system; and

a projection optical system for projecting the light emerging from said illuminated object;

wherein said illuminating optical system is constructed in such a manner that a central area of said illuminated object is illuminated by a light beam from said first high-luminance light-emitting area, and a peripheral area of said illuminated object is illuminated by light beams from said first and second high-luminance light emitting areas;

wherein said illuminating optical system includes;

a reflector for reflecting the light from said light source; and

a lens positioned in the path of the light emerging from said reflector, said lens being provided with an entrance face having a positive refractive power only in the vicinity of the optical axis of said illuminating optical system and being free from refractive power in other areas, and an exit face having a positive power over the entire area.

31. A projector comprising:

a light source having first and second high-luminance light-emitting areas;

an illuminating optical system for directing light, from said light source, toward an object to be illuminated, wherein said first and second high-luminance light-emitting areas are positioned on an optical axis of said illuminating optical system; and

a projection optical system for projecting the light emerging from said illuminated object;

wherein said illuminating optical system is constructed in such a manner that a central area of said illuminated object is illuminated by a light beam from said first high-luminance light-emitting area, and a peripheral area of said illuminated object is illuminated by light beams from said first and second high-luminance light emitting areas;

wherein said illuminating optical system includes;

a main elliptical mirror having a first focal point in said first high-luminance light-emitting area and a second focal point on the axial point of said illuminated object; and

a sub elliptical mirror having a focal point on an axial point displaced from said first focal point of said main elliptical mirror toward said illuminated object.

32. A projector comprising:

light source having first and second high-luminance light emitting areas;

an illuminating optical system for directing light, from said light source, toward an object to be illuminated, wherein said first and second high-luminance light-emitting areas are positioned on an optical axis of said illuminating optical system; and

a projection optical system for projecting the light emerging from said illuminated object;

wherein said illuminating optical system is constructed in such a manner that a central area of said illuminated object is illuminated by a light beam from said first high-luminance light-emitting area, and a peripheral area of said illuminated object is illuminated by light beams from said first and second high-luminance light emitting areas;

wherein said illuminating optical system includes;

a reflector for reflecting the light from said light source; and

a lens provided in the path of light emerging from said reflector, said lens having a negative refractive power in the peripheral area thereof and being free from refractive power in other areas.