Image display apparatus

• US 5,768,024 A
• Filed: 10/10/1995
• Issued: 06/16/1998
• Est. Priority Date: 11/25/1994
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Takahashi, Koichi
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): SCHWARTZ, JORDAN MARC
• Application Number:
  US08/541,531
• Time in Patent Office: 980 Days
• Field of Search: 359/631, 359/630, 359/668, 359/727, 359/728, 359/13, 359/14, 359/16, 359/19
• US Class Current: 359/631
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0132 comprising binocular systems
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0172 characterised by optical features

Abstract

An image display apparatus, e.g. a head-mounted image display apparatus, which enables observation of a clear image at a wide field angle, and which is extremely small in size and light in weight and hence unlikely to cause the observer to be readily fatigued. The image display apparatus has an image display device (6) and an ocular optical system (7). The ocular optical system (7) has a first surface (3), a second surface (4) and a third surface (5), which are disposed in the mentioned order from the observer'"'"'s eyeball (1) side. The space between the first and second surfaces (3 and 4) and the space between the second and third surfaces (4 and 5) are filled with a medium having a refractive index larger than 1. The first and second surfaces (3 and 4) have different curvatures. The second surface (4) is a reflecting or semitransparent surface which is decentered with respect to an observer'"'"'s visual axis (2), and which has a concave surface directed toward the observer'"'"'s eyeball (1). Light rays emanating from the image display device (6) enter the observer'"'"'s eyeball (1) without forming an intermediate image. The light rays are reflected once by the second surface (4) only. Thus, light rays from the image display device (6) are refracted by the third surface (5), reflected by the second surface (4), and further refracted by the first surface (3) so as to enter the observer'"'"'s eyeball (1).

Claims

1. An image display apparatus comprising:

an image display device for displaying an image; and

an ocular optical system constructed and arranged to project an image formed by said image display device and to lead the image into an observer'"'"'s eyeball,

said ocular optical system having at least three surfaces, which are defined as first, second and third surfaces in order from an observer'"'"'s eyeball side, a space between said first and second surfaces and a space between said second and third surfaces being filled with a medium having refractive index larger than 1, said first and second surfaces having different curvatures, said second surface being a reflecting or semitransparent surface which is decentered with respect to an observer'"'"'s visual axis and has a concave surface directed toward said observer'"'"'s eyeball,

wherein light rays emanating from said image display device enter said observer'"'"'s eyeball without forming an intermediate image during travel to said observer'"'"'s eyeball, said light rays being reflected once by said second surface only, and wherein a path of light rays from said image display device is refracted by said third surface, reflected by said second surface, and further refracted by said first surface so as to enter said observer'"'"'s eyeball,

any one of said first, second and third surfaces is an anamorphic surface, and

the first, second and third surfaces of said ocular optical system have positive, positive and negative refractive powers, respectively.

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

space="preserve" listing-type="equation">f.sub.y /f.sub.x >

1 (1)

where f_y is a focal length of said ocular optical system in a plane which contains both said observer'"'"'s visual axis and a center of said image display device, and f_x is a focal length of said ocular optical system in a plane which perpendicularly intersects the plane containing both said observer'"'"'s visual axis and the center of said image display device.

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

space="preserve" listing-type="equation">0.5<

R.sub.y2 /R.sub.x2 <

3 (2)

where R_y2 is a curvature radius of the second surface of said ocular optical system in a plane containing both said observer'"'"'s visual axis and a center of said image display device, and R_x2 is a curvature radius of said second surface in a plane which perpendicularly intersects the plane containing both said observer'"'"'s visual axis and the center of said image display device.

5. An image display apparatus according to claim 4, wherein the curvature radii R_x2 and R_y2 of the second surface of said ocular optical system satisfy the following condition:

space="preserve" listing-type="equation">0.5<

R.sub.y2 /R.sub.x2 ≦

1 (4).

7. An image display apparatus according to claim 1 or 3, wherein the first surface of said ocular optical system has a convex surface directed toward the observer'"'"'s eyeball.

8. An image display apparatus according to claim 1 or 3, wherein the third surface of said ocular optical system has a concave surface directed toward said image display device.

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

space="preserve" listing-type="equation">30°

<

α

<

80°

(6)

where α

is an angle between the second surface of said ocular optical system and said observer'"'"'s visual axis.

10. An image display apparatus according to claim 1 or 3, wherein a display surface of said image display device is tilted with respect to said observer'"'"'s visual axis.

3. An image display apparatus comprising:

an image display device for displaying an image; and

an ocular optical system constructed and arranged to project an image formed by said image display device and to lead the image into an observer'"'"'s eyeball,

said ocular optical system having at least three surfaces, which are defined as first, second and third surfaces in order from an observer'"'"'s eyeball side, a space between said first and second surfaces and a space between said second and third surfaces being filled with a medium having refractive index larger than 1, said first and second surfaces having different curvatures, said second surface being a reflecting or semitransparent surface which is decentered with respect to an observer'"'"'s visual axis and has a concave surface directed toward said observer'"'"'s eyeball,

wherein light rays emanating from said image display device enter said observer'"'"'s eyeball without forming an intermediate image during travel to said observer'"'"'s eyeball, said light rays being reflected once by said second surface only, and wherein a path of light rays from said image display device is refracted by said third surface, reflected by said second surface, and further refracted by said first surface so as to enter said observer'"'"'s eyeball, and

which satisfies the following condition;

space="preserve" listing-type="equation">1<

R.sub.y2 /R.sub.x2 <

3

where R_y2 is a curvature radius of the second surface of said ocular optical system in a plane containing both said observer'"'"'s visual axis and a center of said image display device, and R_x2 is a curvature radius of said second surface in a plane which perpendicularly intersects the plane containing both said observer'"'"'s visual axis and the center of said image display device.

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

space="preserve" listing-type="equation">-1>

(.o slashed..sub.1 +.o slashed..sub.2)/.o slashed..sub.3 >

-15(5)

where .o slashed.₁, .o slashed.₂ and .o slashed.₃ are refractive powers of the first, second and third surfaces of said ocular optical system.

11. An image display apparatus comprising:

an image display device for displaying an image; and

an ocular optical system constructed and arranged to project an image formed by said image display device and to lead the image into an observer'"'"'s eyeball,

said ocular optical system having at least three surfaces, which are defined as first, second and third surfaces in order from an observer'"'"'s eyeball side, a space between said first and second surfaces and a space between said second and third surfaces being filled with a medium having refractive index larger than 1, said first and second surfaces having different curvatures, said second surface being a reflecting or semitransparent surface which is decentered with respect to an observer'"'"'s visual axis and has a concave surface directed toward said observer'"'"'s eyeball,

wherein light rays emanating from said image display device enter said observer'"'"'s eyeball without forming an intermediate image during travel to said observer'"'"'s eyeball, said light rays being reflected once by said second surface only, and wherein a path of light rays from said image display device is refracted by said third surface, reflected by said second surface, and further refracted by said first surface so as to enter said observer'"'"'s eyeball, and

said second surface of said ocular optical system is an anamorphic surface.

12. An image display apparatus comprising:

an image display device for displaying an image; and

an ocular optical system constructed and arranged to project an image formed by said image display device and to lead the image into an observer'"'"'s eyeball,

said ocular optical system having at least three surfaces, which are defined as first, second and third surfaces in order from an observer'"'"'s eyeball side, a space between said first and second surfaces and a space between said second and third surfaces being filled with a medium having refractive index larger than 1, said first and second surfaces having different curvatures, said second surface being a reflecting or semitransparent surface which is decentered with respect to an observer'"'"'s visual axis and has a concave surface directed toward said observer'"'"'s eyeball,

wherein light rays emanating from said image display device enter said observer'"'"'s eyeball without forming an intermediate image during travel to said observer'"'"'s eyeball, said light rays being reflected once by said second surface only, and wherein a path of light rays from said image display device is refracted by said third surface, reflected by said second surface, and further refracted by said first surface so as to enter said observer'"'"'s eyeball, and

which satisfies the following condition;

space="preserve" listing-type="equation">1<

R.sub.y2 /R.sub.x2 <

3

where R_y2 is a curvature radius of the second surface of said ocular optical system in a plane containing both said observer'"'"'s visual axis and a center of said image display device, and R_x2 is a curvature radius of said second surface in a plane which perpendicularly intersects the plane containing both said observer'"'"'s visual axis and the center of said image display device, and

the first, second and third surfaces of said ocular optical system have positive, positive and negative refractive powers, respectively.

13. An image display apparatus comprising:

a face-mounted unit body having an image display device disposed in front of an observer'"'"'s face with a display surface thereof directed toward an observer'"'"'s visual axis so that a line normal to the display surface intersects an observer'"'"'s visual axis;

an ocular optical system having

a first surface provided at a position which faces the observer'"'"'s eyeball,

a second surface disposed to face said first surface such that a spacing between said first and second surfaces gradually increases toward said image display device from the observer'"'"'s visual axis,

a third surface provided so that said third surface faces the display surface of said image display device, and that one end of said third surface intersects an extension of said first surface, and the other end of said third surface intersects an extension of said second surface, and a medium which is surrounded by said first, second and third surfaces, and which has a refractive index (n) larger than 1 (n>

1); and

a support member for supporting said face-mounted unit body on an observer'"'"'s head so that said face-mounted unit body is held fit to the observer'"'"'s face,

said second surface being a reflecting surface that reflects light rays in said ocular optical system, and said second surface having such a surface configuration that a surface configuration in a plane (YZ-plane) containing light rays turned back by said reflecting surface is different from a surface configuration in a XZ-plane perpendicular said YZ-plane.

14. An image display apparatus according to claim 13, wherein said face-mounted unit body includes a see-through optical element provided at a side of said ocular optical system which is remote from the observer'"'"'s eyeball, said see-through optical element having a fourth surface disposed according to one of A and B, such that A said fourth surface is in substantially uniform contact with said second surface, and B said fourth surface is proximate to and facing said second surface of said ocular optical system, said see-through optical element further having a medium which has a refractive index (n) larger than 1 (n>

1) and a fifth surface provided to face said fourth surface across said medium, and a see-through switching shutter disposed at a position which is on the observer'"'"'s visual axis, and which faces the fifth surface of said see-through optical element.

15. An image display apparatus according to claim 14, wherein said see-through optical element is provided to face said ocular optical system across an air spacing.

16. An image display apparatus according to claim 14, wherein said see-through optical element is cemented to said ocular optical system.

17. An image display apparatus according to claim 13, wherein said third surface of said ocular optical system has a concave surface directed toward said image display device.