Computer graphics processing and selective visual display system – Image superposition by optical means
Reexamination Certificate
2001-03-28
2003-11-25
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Image superposition by optical means
C345S008000, C345S009000, C345S102000, C348S115000, C349S011000, C349S013000, C359S013000, C359S015000, C359S630000, C359S631000, C359S633000
Reexamination Certificate
active
06653989
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a composite display apparatus including an image-pickup optical system for guiding light from the image information of its external world to an image-pickup device and a display optical system for guiding light exiting from a liquid crystal display etc. to the eyeballs of an observer.
BACKGROUND OF THE INVENTION
There have been proposed units including a head mounted display (HMD) and a miniature CCD camera attached thereto and displaying image information obtained from the camera on a display device included in the HMD directly or after subjecting the image information to some image processing. There have also been proposed various see-through type HMDs which use optical coupling/separating devices, such as a half mirror, and enable not only the observation of images displayed on a display device, but also the direct observation of its external world at an angular magnification of ×1.
In the above forms of HMDs, a difference between the ocular optical axis of the display optical system, which is for allowing the person equipped with the HMD to observe the image information displayed on the display device of the HMD, and the optical axis of the CCD camera (image-pickup optical system), which is for allowing the image information of its external world to form an image on the CCD surface, results in parallax.
So there have been proposed units including both image-pickup optical system and display optical system which is free from parallax in Japanese Patent Application Laid-Open No. 4-22358 and Japanese Patent Application Laid-Open No. 5-303053.
The display optical system of the visual aid unit proposed in Japanese Patent Application Laid-Open No. 4-22358 is constructed in such a manner that light emitted from a miniature liquid crystal display unit passes through a plane half mirror and then is guided to eyeballs by an ocular. On the other hand, the image-pickup optical system of the same is constructed in such a manner that light of its external world passes through the plane half mirror and then forms an image in a miniature camera which is provided in such a position as to face the liquid crystal device across the half mirror. This visual aid unit, however, tends to be large because the plane half mirror used in the unit is arranged at an angle of 45 degrees. In addition, this unit cannot apply to see-thorough type units because there is arranged an ocular in front of the eyeballs of an observer.
On the other hand, in Japanese Patent Application Laid-Open No. 5-303053, there is disclosed a head mounted display system which includes an image pickup optical system and a display optical system and is capable of constituting a see-through type unit; however, the unit has a complicated optical system and tends to be very large.
The applicants of the present invention have already overcome these problems and proposed composite display apparatus in Japanese Patent Application Laid-Open No. 11-174367 which includes a display optical system with more than one eccentric reflection surface for guiding a light beam from a display means, such as a liquid crystal display (LCD), to the eyeballs of an observer and an image-pickup optical system for allowing image information of its external world to form an image on the surface of an image-pickup device, such as CCD, and enable preventing the light beam from the display means from entering the pickup surface of the image-pickup optical system, in addition, observing the image information of both optical systems and creating an image of the same in a good state where there results no parallax while allowing the entire unit to be miniaturized.
FIG. 10
is a schematic view showing the main part of one form of the composite display apparatus proposed in Japanese Patent Application Laid-Open No. 11-174367. In the same figure, reference numeral
101
denotes a display optical system (LCD display optical system) which consists of a prism body
9
a
utilizing more than one internal reflection, includes more than one eccentric reflection surface each having more than one eccentric curvature, and realizes a color display using a ferroelectric display device
2
(FLCD), as a display means, by illuminating the display device with three light sources
31
R,
31
G and
31
B radiating respective color light in a time-sharing manner one by one while synchronizing the illumination with the display of the color image separated into colors R, G and B. R, G and B images are displayed within {fraction (1/60)} to {fraction (1/30)} seconds altogether utilizing the afterimage effect. Each of the light sources
31
R,
31
G and
31
B can be constructed by combining a white-light source and a color filter. The image information displayed on the FLCD
2
is guided to the eyeballs of an observer through a display optical system
101
. The display optical system
101
a
is an optical axis.
Reference numeral
102
denotes an image-pickup optical system (CCD image-pickup optical system) which, like the display optical system
101
, consists of a prism body
9
c
utilizing more than one internal reflection, includes more than one eccentric reflection surface each having more than one eccentric curvature, and images the image information of its external world on an image-pickup device (CCD)
3
. Reference numeral
102
a
is an optical axis of the image-pickup optical system. The display optical system
101
and the image-pickup optical system
102
are joined together via an optical path separating means
4
.
The optical path separating means
4
consists of eccentrically curved reflection surfaces, which separate the optical paths from the display optical system
101
and from the image-pickup optical system
102
. The optical path separating means
4
consists of eccentric reflection surfaces, the surface on one side being used in the display optical system
101
and the surface on the other side being used in the image-pickup optical system
102
.
The light beam from the image information displayed on the FLCD
2
exits in the form of linearly polarized light. PP denotes a sheet polarizer and its polarization axis are established in such a direction as to be at right angle to the polarization axis of the linearly polarized light radiated from the FLCD
2
. Thus, the linearly polarized light from the FLCD
2
is prevented from entering a CCD
3
through an optical system
6
via the optical path separating means
4
and prism body
9
c,
as described later. Reference numeral
5
denotes a diaphragm. Numeral
6
denotes an optical system which images the image of its external world entering via the prism body
9
c
on a CCD
3
surface.
Further, this composite display apparatus allows its external world to be visible through the prism bodies
9
a,
9
c;
accordingly, it can constitute a see-through type unit. In other words, the users of this composite display apparatus observe an image which is the superposition of image information of its external world and that displayed on the FLCD
2
. When establishing a see-through optical system
103
, in addition to the display optical system
101
and the image-pickup optical system
102
, for observing image information of its external world alone, the reflection surface of the optical path separating means
4
is a half mirror (the transmittance-to-reflectance ratio is not limited to 50%:50%, but is arbitrary) and the refractive index of the materials of the prism bodies
9
a,
9
c
of both optical systems
101
,
102
are the same. Reference numeral
1
c
denotes an optical axis of the see-through optical system
103
(external world optical axis).
In
FIG. 10
, the optical axis
101
a
of the display optical system
101
, the optical axis
102
a
of the image-pickup optical system
102
and the optical axis
1
c
of the see-through optical system
103
coincide at the optical path separating means
4
and become co-axial with an ocular optical axis
1
a.
Establishing each constituent as above enables a miniaturized optical system. Further, establishing the refrac
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hjerpe Richard
Tran Henry N.
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