Image display apparatus

• US 6,313,950 B1
• Filed: 03/15/2000
• Issued: 11/06/2001
• Est. Priority Date: 11/06/1997
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Togino, Takayoshi, Hayakawa, Kazuhito, Oode, Hisashi
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): SEYRAFI, SAEED HMT
• Application Number:
  US09/526,426
• Time in Patent Office: 601 Days
• Field of Search: 359/618, 359/628, 359/630, 359/631, 359/632, 359/633, 359/637, 359/640, 359/720, 345/7, 345/8, 345/9
• US Class Current: 359/630
• CPC Class Codes: G02B 17/0816 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0832 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/086 wherein the system is made of a single block of optical material, e.g. solid catadioptric systems
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/123 The splitting element being a lens or a system of lenses, including arrays and surfaces with refractive power
• CPC Class Codes: G02B 27/126 The splitting element being a prism or prismatic array, including systems based on total internal reflection

Abstract

An optical system for an ocular optical system or a projection optical system, in which a plurality of illuminating light sources of different colors can be placed in a side-by-side relation to each other, and which makes it possible to reduce the overall size and weight of an apparatus such as a head-mounted image display apparatus or a color film projection apparatus. The optical system has an image-forming optical system (1) that projects a real image or virtual image of an object placed in an image plane (3). The image-forming optical system (1) has an entrance pupil (5) at a position on the side of the image plane (3) remote from the image-forming optical system. An exit pupil (4) is located in a conjugate relation to the entrance pupil (5) with respect to the image-forming optical system (1). A chromatic aberration producing device (6) is provided between the entrance pupil (5) and the exit pupil (4). Even if a plurality of illuminating light sources of different colors are placed in a side-by-side relation to each other on the entrance pupil (5), rays from the different light sources can pass the exit pupil (4), being superimposed on one another, without chromatic aberration.

Claims

1. An image display apparatus comprising:

a reflection type image display device adapted to form an image plane to be viewed by an observer by reflecting light rays;

an illuminating device to emit light rays to illuminate said image plane; and

an optical system to lead image rays reflected from said reflection type image display device to an eyeball of the observer;

said optical system being an image-forming optical system forming an exit pupil by forming an image of said entrance pupil at a position where said eyeball of the observer is placed;

wherein said illuminating device is arranged to be capable of applying a bundle of light rays to a surface of said image display device closer to said optical system from at least a space between said image display device and said optical system;

said image display apparatus further comprising;

pupil-dividing means for reproducing a multiplicity of images of said entrance pupil on said exit pupil at respective positions displaced relative to each other, said pupil-dividing means being provided between said entrance pupil and said exit pupil.

2. An image display apparatus according to claim 1, wherein said image-forming optical system includes at least a decentered prism member,

wherein illuminating light rays emitted from said illuminating device enter said decentered prism member, travel through a prism medium and exit said decentered prism member to illuminate said reflection type image display device.

3. An image display apparatus according to claim 2, wherein said decentered prism member includes at least:

an entrance surface through which a bundle of light rays enters said decentered prism member;

a reflecting surface to reflect the light rays within said decentered prism member; and

an exit surface through which the light rays exit said decentered prism member;

wherein at least one of said entrance surface, reflecting surface and exit surface is an aspherical surface having a rotationally curved surface configuration.

4. An image display apparatus according to claim 3, wherein said aspherical surface having a rotationally asymmetric curved surface configuration is a free-form surface having only one plane of symmetry.

5. An optical system according to any one of claims 2 &

4, wherein said image-forming optical system is a decentered prism optical system having three optical surfaces that surround a medium having a refractive index larger than 1, said exit pupil being located to face said first surface, and said image plane being disposed to face said third surface, so that display light from the object placed in said image plane enters said decentered prism optical system through said third surface, which has a transmitting action, and is reflected by an inner side of said first surface, which faces said exit pupil and has both a reflecting action and a transmitting action, and the reflected light is incident on said second surface, which is located on an opposite side to said exit pupil with respect to said first surface, and is reflected by an inner side of said second surface, and the reflected light exits from said decentered prism optical system through said first surface.

6. An optical system according to any one of claims 2 &

4, wherein said pupil-dividing means is provided between said decentered prism optical system and said entrance pupil.

7. An optical system according to any of claims 2 &

4, wherein said pupil-dividing means is provided between said decentered prism optical system and said image plane.

8. An optical system according to any of claims 2 &

4, wherein said pupil-dividing means is provided between said exit pupil and said decentered prism optical system.

9. An optical system according to any of claims 2 &

4, wherein said pupil-dividing means is a two-dimensional diffraction grating.

10. An optical system according to any of claims 2 &

4, wherein said pupil-dividing means is a pair of superimposed lenticular lens plates whose groove directions perpendicularly intersect each other.

11. An optical system according to any one of claims 2 &

4, wherein said pupil-dividing means is a birefringent plate.

12. An optical system according to any of claims 2 &

4, wherein said pupil-dividing means is a micro lens array.

13. An optical system according to any of claims 2 &

4, wherein an illuminating light source is placed at a position of said entrance pupil.

14. An image display apparatus according to any one of claims 2 to 4, wherein said illuminating light rays entering said decentered prism member pass through said prism medium while intersecting an optical path of said image rays in said decentered prism member at least once before exiting said decentered prism member.

15. An image display apparatus according to any one of claims 1, or 2 to 4, wherein said image-forming optical system includes at least a decentered prism member,

wherein illuminating light rays emitted from said illuminating device are applied to said reflection type image display device without passing through said decentered prism member.

16. An image display apparatus comprising:

a reflection type image display device adapted to form an image plane to be viewed by an observer by reflecting light rays;

an illuminating device to emit light rays to illuminate said image plane; and

an optical system to lead image rays reflected from said reflection type image display device to an eyeball of the observer;

said optical system being an image-forming optical system forming an exit pupil by forming an image of said entrance pupil at a position where said eyeball of the observer is placed;

wherein said illuminating device is arranged to be capable of applying a bundle of light rays to a surface of said image display device closer to said optical system from at least a space between said image display device and said optical system;

said image display apparatus further comprising;

a pupil-divider to reproduce a multiplicity of images of said entrance pupil on said exit pupil at respective positions displaced relative to each other, said pupil-divider being provided between said entrance pupil and said exit pupil.