Image display apparatus

Claim 2

An image display apparatus comprising: image display means for displaying an image; and a projection optical system for leading said image to an observation region, said projection optical system including: a reflecting and transmitting member having reflecting and transmitting functions disposed on an optical path of said image display means, a reflecting member disposed so as to form a turn-back optical path between said reflecting member and said reflecting and transmitting member, a refractive member having refractive power, said refractive member being arranged to produce at least positive chromatic aberration, and a diffraction optical element arranged to produce at least negative chromatic aberration, at least one of said refractive member and said diffraction optical element being disposed in an optical path between said reflecting and transmitting member and said observation region.

Claim 3

An image display apparatus comprising: image display means for displaying an image; and a projection optical system for leading said image to an observation region, said projection optical system including: a reflecting and transmitting member having reflecting and transmitting functions disposed on an optical path of said image display means, a reflecting member disposed so as to form a turn-back optical path between said reflecting member and said reflecting and transmitting member, and a combination element disposed in an optical path between said reflecting and transmitting member and said observation region, said combination element comprising: a refractive member having refractive power, said refractive member being arranged to produce at least positive chromatic aberration, and a diffraction optical element arranged to produce at least negative chromatic aberration.

Claim 4

An image display apparatus comprising: image display means for displaying an image; and a projection optical system for leading said image to an observation region, said projection optical system including: a reflecting and transmitting member having reflecting and transmitting functions disposed on an optical path of said image display means, a reflecting member disposed so as to form a turn-back optical path between said reflecting member and said reflecting and transmitting member, and a combination element disposed in an optical path between said reflecting and transmitting member and said observation region, said combination element comprising: a refractive member having refractive power, said refractive member being arranged to produce at least positive chromatic aberration, and a diffraction optical element arranged to produce at least negative chromatic aberration.

Claim 5

An image display apparatus according to claim 1 or 2, wherein: said refractive member and said diffraction optical element are formed so that at least a part of chromatic aberration produced by one of said refractive member and said diffraction optical element is cancelled by the other of said refractive member and said diffraction optical element.

Claim 6

An image display apparatus according to claim 1 or 2, wherein: said refractive member is one of a refracting surface of positive power and a positive refracting lens, and said diffraction optical element has positive power and is disposed between said reflecting and transmitting member and said reflecting member.

Claim 7

An image display apparatus according to claim 1 or 2, wherein: said diffraction optical element has positive power as a whole; and said refractive member and said diffraction optical element are disposed between an eyeball of said user and said reflecting and transmitting member.

Claim 8

An image display apparatus according to claim 1 or 2, wherein: said diffraction optical element has positive power and is disposed between an eyeball of said user and said reflecting and transmitting member; and said refractive member is one of a refracting surface of positive power and a positive refracting lens and is disposed between said reflecting and transmitting member and said reflecting member.

Claim 9

An image display apparatus according to claim 1 or 2, wherein: said diffraction optical element is a hybrid element having a combination of a refracting optical component and a diffraction optical element component, which are integrated with each other.

Claim 10

An image display apparatus according to claim 7, wherein: said hybrid element is made of a plastic material.

Claim 11

An image display apparatus according to claim 7, wherein: said hybrid element includes at least a doublet lens.

Claim 12

An image display apparatus according to claim 1 or 2, wherein: said diffraction optical element is a reflective diffraction optical element having a diffraction surface formed on a surface of said reflecting member.

Claim 13

An image display apparatus according to claim 1 or 2, wherein: said diffraction optical element has an aspherical action of pitch distribution such that a power of said diffraction optical element becomes weaker than a power of a paraxial spherical system, as a distance from an optical axis through said diffraction optical element increases.

Claim 14

An image display apparatus according to claim 1 or 2, wherein: said reflecting member is a concave reflecting mirror.

Claim 15

An image display apparatus according to claim 1 or 2, wherein: said reflecting and transmitting member is a prism having a semitransparent reflecting surface.

Claim 16

An image display apparatus according to claim 13, wherein: said prism is a plastic prism.

Claim 17

An image display apparatus according to claim 13, wherein: an end surface of said prism on a side thereof which faces said image display means is an aspherical surface.

Claim 18

An image display apparatus according to claim 13, wherein said projection optical system further comprises: an aspherical lens disposed between said image display means and said prism.

Claim 19

In an image display apparatus comprising means for displaying an image, and a projection optical system for leading said image to an observation region, said projection optical system including: a member having reflecting and transmitting functions disposed on an optical path of said image display means as optical axis bending means; a reflecting member disposed so as to form a turn-back optical path between it and said member having reflecting and transmitting functions; a member having refractive power; and a diffraction optical element; at least either said member having refractive power or said diffraction optical element being disposed in an optical path between said member having reflecting and transmitting functions and said observation region, which includes said turn-back optical path; said image display apparatus satisfying the following condition: 0.033<Σ(f/f.sub.DOE)<0.19 (1) where f is the focal length of the entire optical system for light of a given order of diffraction, f DOE is the focal length of said diffraction optical element for the light of a given order of diffraction, and Σ means summation carried out in a case where there are a plurality of diffraction optical elements.

Claim 20

In an image display apparatus comprising means for displaying an image, and a projection optical system for leading said image to an observation region, said projection optical system including: a member having reflecting and transmitting functions disposed on an optical path of said image display means as optical axis bending means; a reflecting member disposed so as to form a turn-back optical path between it and said member having reflecting and transmitting functions; a member having refractive power; and a diffraction optical element; at least either said member having refractive power or said diffraction optical element being disposed in an optical path between said member having reflecting and transmitting functions and said observation region, which includes said turn-back optical path; said image display apparatus satisfying the following condition: 0.033<Σ(f/f.sub.DOE)<0.19 (1) where f is the focal length of the entire optical system for light of a given order of diffraction, f DOE is the focal length of said diffraction optical element for the light of a given order of diffraction, and Σ means summation carried out in a case where there are a plurality of diffraction optical elements.

Claim 21

In an image display apparatus comprising means for displaying an image, and a projection optical system for leading said image to an observation region, said projection optical system including: a member having reflecting and transmitting functions disposed on an optical path of said image display means as optical axis bending means; a reflecting member disposed so as to form a turn-back optical path between it and said member having reflecting and transmitting functions; and a combination of a member having refractive power and a diffraction optical element, which are disposed in an optical path between said member having reflecting and transmitting functions and said observation region, which includes said turn-back optical path; said image display apparatus satisfying the following condition: 0.033<Σ(f/f.sub.DOE)<0.19 (1) where f is the focal length of the entire optical system for light of a given order of diffraction, f DOE is the focal length of said diffraction optical element for the light of a given order of diffraction, and Σ means summation carried out in a case where there are a plurality of diffraction optical elements.

Claim 22

In an image display apparatus comprising means for displaying an image, and a projection optical system for leading said image to an observation region, said projection optical system including: a member having reflecting and transmitting functions disposed on an optical path of said image display means as optical axis bending means; a reflecting member disposed so as to form a turn-back optical path between it and said member having reflecting and transmitting functions; and a combination of a member having refractive power and a diffraction optical element, which are disposed in an optical path between said member having reflecting and transmitting functions and said observation region, which includes said turn-back optical path; said image display apparatus satisfying the following condition: 0.033<Σ(f/f.sub.DOE)<0.19 (1) where f is the focal length of the entire optical system for light of a given order of diffraction, f DOE is the focal length of said diffraction optical element for the light of a given order of diffraction, and Σ means summation carried out in a case where there are a plurality of diffraction optical elements.

Claim 23

In an image display apparatus comprising means for displaying an image, and a projection optical system for leading said image to an observation region, said projection optical system including: a member having reflecting and transmitting functions disposed on an optical path of said image display means as optical axis bending means; a reflecting member disposed so as to form a turn-back optical path between it and said member having reflecting and transmitting functions; a member having refractive power; and a diffraction optical element; at least either said member having refractive power or said diffraction optical element being disposed in an optical path between said member having reflecting and transmitting functions and said observation region, which includes said turn-back optical path; said image display apparatus satisfying the following condition: 15<f<60 (2) where f is the focal length of the entire optical system for light of a given order of diffraction.

Claim 24

In an image display apparatus comprising means for displaying an image, and a projection optical system for leading said image to an observation region, said projection optical system including: a member having reflecting and transmitting functions disposed on an optical path of said image display means as optical axis bending means; a reflecting member disposed so as to form a turn-back optical path between it and said member having reflecting and transmitting functions; a member having refractive power; and a diffraction optical element; at least either said member having refractive power or said diffraction optical element being disposed in an optical path between said member having reflecting and transmitting functions and said observation region, which includes said turn-back optical path; said image display apparatus satisfying the following condition: 15<f<60 (2) where f is the focal length of the entire optical system for light of a given order of diffraction.

Claim 25

In an image display apparatus comprising means for displaying an image, and a projection optical system for leading said image to an observation region, said projection optical system including: a member having reflecting and transmitting functions disposed on an optical path of said image display means as optical axis bending means; a reflecting member disposed so as to form a turn-back optical path between it and said member having reflecting and transmitting functions; and a combination of a member having refractive power and a diffraction optical element, which are disposed in an optical path between said member having reflecting and transmitting functions and said observation region, which includes said turn-back optical path; said image display apparatus satisfying the following condition: 15<f<60 (2) where f is the focal length of the entire optical system for light of a given order of diffraction.

Claim 26

In an image display apparatus comprising means for displaying an image, and a projection optical system for leading said image to an observation region, said projection optical system including: a member having reflecting and transmitting functions disposed on an optical path of said image display means as optical axis bending means; a reflecting member disposed so as to form a turn-back optical path between it and said member having reflecting and transmitting functions; and a combination of a member having refractive power and a diffraction optical element, which are disposed in an optical path between said member having reflecting and transmitting functions and said observation region, which includes said turn-back optical path; said image display apparatus satisfying the following condition: 15<f<60 (2) where f is the focal length of the entire optical system for light of a given order of diffraction.