Image display apparatus

• US 5,812,100 A
• Filed: 06/01/1995
• Issued: 09/22/1998
• Est. Priority Date: 06/01/1994
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Kuba, Keiichi
• Primary Examiner(s): Liang, Regina
• Application Number:
  US08/457,375
• Time in Patent Office: 1,209 Days
• Field of Search: 345/7, 345/8, 348/115, 348/53, 340/980, 434/94, 359/13, 359/630, 359/738, 359/638
• US Class Current: 345/8
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: H04N 5/7491 of head mounted projectors

Abstract

A compact, lightweight and wide-field head-mounted image display apparatus which is capable of projecting an image overflowing with a sence of immersion. The apparatus includes an LCD (1), a beam splitter prism (5) having a half-mirror (3) which is disposed at a tilt at an intersection between the optical axis of the LCD (1) and the observer'"'"'s visual axis to lead an image ray bundle emanating from the LCD (1) to a pupil (4) of an observer'"'"'s eyeball, and a concave mirror (2) which is provided on a surface of the prism (5) on the side thereof which is remote from the LCD (1). Thus, after entering the prism (5), the image displayed on the LCD (1) is successively reflected by the concave mirror (2) and the half-mirror (3) and then enters the eyeball (4). The effective apertures of the half-mirror (3), the concave mirror (2) and the beam splitter prism (5) are reduced, thereby making the image of the periphery of the image display device unsharp, and thus providing dynamic presence.

Claims

1. An Image display apparatus comprising:

an apparatus body unit including an image device; and

a support member which enables said apparatus body unit to be fitted to an observer'"'"'s face or head,

said apparatus body unit comprising an ocular optical system for leading an image displayed by said image display device to an eyeball of an observer who is fitted with said apparatus body unit, and contrast reducing means whereby a contrast of a peripheral region of said image is made lower than a contrast of a central region of said image,

wherein said contrast reducing means allows said image to become gradually darker from a predetermined position of said image display device as a distance therefrom increases toward a periphery of said image display device, thereby making an image of the periphery of said image display device unsharp,

said contrast reducing means has a principal ray cutoff means for cutting off at least a principal ray in a ray bundle emanating from a most peripheral region of said image display device, said principal ray cut-off means being disposed at a position away from said image display device by a distance which is not shorter than a depth of focus, and

said principal ray cutoff means has the following features;

said principal ray cutoff means is disposed between said image display device and said ocular optical system,

said principal ray cutoff means cuts off the principal ray from the most peripheral region of said image display device and transmits a marginal ray closer to a center of said image display device than said principal ray in said ray bundle emanating from the most peripheral region, and

said principal ray cutoff means allows an image of said image display device over an area from the center to the periphery thereof to be led to said observer'"'"'s eyeball through said ocular optical system, and the image of said periphery is made darker than the image of the center of said image display device.

2. An image display apparatus according to claim 1, wherein an image of said principal ray cut-off means which is formed by said ocular optical system lies at a position which is 25 millimeters or more away from said eyeball.

3. An image display apparatus according to claim 1, which satisfies the following condition:

space="preserve" listing-type="equation">|A-B|>

3 m.sup.-1

where A (m^-1) is a position where an image of said image display device is formed by said ocular optical system, and B (m^-1) is a position where an image of said principal ray cut-off means is formed by said ocular optical system.

4. An image display apparatus according to claim 1, wherein said contrast reducing means has a ray bundle cutoff means for cutting off all of a ray bundle emanating from the most peripheral region of said image display device, said ray bundle cut-off means being disposed at a position away from said image display device by a distance which is not shorter than a depth of focus.

5. An image display apparatus according to claim 4, wherein said ray bundle cut-off means is disposed at a position which is f² /333 (millimeters) or more away from said image display device, where f (millimeters) is a focal length of said ocular optical system.

16. An image display apparatus according to any one of claims 1, 2 and 3 to 8, wherein said ocular optical system has a half-mirror and a concave mirror.

17. An image display apparatus according to any one of claims 1, 2 and 3 to 8, wherein said ocular optical system includes a prism having a half-mirror.

18. An image display apparatus according to any one of claims 1, 2, 3 to 8, and 9 to 14, wherein said prism is made of a plastic material.

19. An image display apparatus according to any one of claims 1, 2, 3 to 8, and 9 to 14, wherein one of an end surface of said prism which faces said image display device or a lens which is disposed between said image display device and said prism has an aspherical surface, said aspherical surface being designed so that negative power added increases as the distance from an optical axis increases toward a periphery as far as a predetermined position in an effective aperture region.

20. An image display apparatus according to any one of claims 1, 2, 3 to 8, and 9 to 14, wherein an eye relief of said ocular optical system is 20 millimeters or more.

21. An image display apparatus according to any one of claims 1, 2, 3 to 8, and 9 to 14, wherein said ocular optical system displays an outside-world image in such a manner that said outside-world image is superimposed on a periphery of the image of said image display device.

6. An image display apparatus comprising:

an apparatus body unit including an image device; and

a support member which enables said apparatus body unit to be fitted to an observer'"'"'s face or head,

said apparatus body unit comprising

an ocular optical system for leading an image displayed by said image display device to an eyeball of an observer who is fitted with said apparatus body unit,

contrast reducing means whereby a contrast of a peripheral region of said image is made lower than a contrast of a central region of said image,

illuminating means for illuminating said image display device, and

illuminance reducing means disposed between said image display device and said illuminating means, said illuminance reducing means being arranged such that illuminance of light illuminating a peripheral region of said image display device is lower than illuminance of light illuminating a central region of said image display device,

wherein said contrast reducing means allows said image to become gradually darker from a predetermined position of said image display device as a distance therefrom increases toward a periphery of said image display device, thereby making an image of the periphery of said image display device unsharp.

7. An image display apparatus according to claim 6, wherein said illuminance reducing means comprises a light-blocking member in which transmittance gradually decreases as a distance from a center thereof increases toward a periphery thereof.

8. An image display apparatus according to claim 6, wherein said illuminance reducing means is implemented by disposing said illuminating means away from said image display device by a distance at which said illuminating means generates illumination unevenness such that the periphery of said image display device is darker than the center thereof.

9. An image display apparatus comprising:

an apparatus body unit including an image display device; and

a support member which enables said apparatus body unit to be fitted to an observer'"'"'s face or head,

said apparatus body unit comprising an ocular optical system for leading an image displayed by said image display device to an eyeball of an observer who is fitted with said apparatus body unit,

wherein said ocular optical system has a configuration arranged to cut off at least a principal ray emanating from a most peripheral region of said image display device between a surface of said ocular optical system closest to said image display device and a surface of said ocular optical system closest to the observer'"'"'s eyeball so that said principal ray does not reach the observer'"'"'s eyeball, whereby when the observer sees said image, a contrast of a peripheral region of said image is lower than a contrast of a central region of said image, thereby making a boundary between an image display area and a non-image display area indistinct.

10. An image display apparatus according to claim 9, wherein said configuration of said ocular optical system is arranged such that an effective aperture of said ocular optical system is reduced to narrow a width of light led from said surface closest to said image display device to said surface closest to said observer'"'"'s eyeball so that the principal ray emanating from the most peripheral region of said image display device falls outside said width of light, thereby being cut off.

11. An image display apparatus according to claim 9, wherein said ocular optical system has a mirror surface, said mirror surface having a mirror-coated reflecting surface in a central portion thereof and one of a transmitting surface and an absorbing surface formed in a portion surrounding said reflecting surface, so that the principal ray emanating from the most peripheral region of said image display device is cut off by said transmitting surface or absorbing surface.

12. An image display apparatus according to claim 10, wherein said ocular optical system has a prism member, said prism member having an effective aperture reduced so that the principal ray emanating from the most peripheral region of said image display device and entering said prism member exits from said prism member through a side surface thereof, thereby being cut off without reaching said observer'"'"'s eyeball.

13. An image display apparatus according to claim 11, wherein said ocular optical system has a prism member, and said mirror surface is a concave mirror of said prism member.

14. An image display apparatus according to claim 11, wherein said ocular optical system has a prism member, and said mirror surface is a half mirror of said prism member.

15. An image display apparatus according to claim 12, 13 or 14, wherein said prism member has an entrance surface disposed closest to said image display device, an exit surface disposed closest to said observer'"'"'s eyeball, a concave mirror, and a half-mirror, so that a principal ray emanating from a central region of said image display device passes through said entrance surface and further passes through said half-mirror and is then reflected by said concave mirror, and the reflected principal ray is reflected by said half-mirror and passes through said exit surface so as to be led to said observer'"'"'s eyeball.