Optical: systems and elements – Single channel simultaneously to or from plural channels – By partial reflection at beam splitting or combining surface
Reexamination Certificate
2001-04-19
2003-11-11
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By partial reflection at beam splitting or combining surface
C359S630000, C359S633000, C359S637000, C359S639000
Reexamination Certificate
active
06646811
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an optical element and a compound display apparatus using the same.
Besides, this invention relates to an optical system suitable for an image pickup display apparatus or the like which is enhanced in the degree of freedom of layout by the use of an optical element which is thin (thin in the direction of the visual axis) and is easy in the display and image pickup at a wide angle of field and has a free curved surface.
Besides, this invention relates to a compound display apparatus which has an image pickup optical system for introducing light from the image information of the external world and forming an image on an image pickup element and a display optical system for observing therethrough the image information displayed on display means such as liquid crystal and which is generally downsized, and particularly is suitable for an apparatus called a head mounted display (HMD) or a spectacle type display.
2. Related Background Art
There have heretofore been proposed an apparatus in which a compact CCD camera is mounted on an HMD and image information obtained from the compact CCD camera is intactly displayed on the HMD, and an apparatus in which image information obtained from a compact CCD camera is processed and converted into discrete image information, which is then displayed on an HMD. Also, there have been proposed various see-through type HMD's (HMD's designed such that the light of the external world can be directly observed at an angular magnification of about 1).
In the HMD's of such a form, it is not preferable that when the eyeball optical axis of a display optical system for observing therethrough the image information displayed on the display means of the HMD and the optical axis of the CCD camera for imaging the image information of the external world on the surface of the CCD differ from each other, a parallax occurs between these. An apparatus having an image pickup optical system and a display optical system with no parallax each other is proposed in Japanese Patent Application Laid-Open No. 4-22358 and Japanese Patent Application Laid-Open No. 5-303053.
The display optical system proposed in Japanese Patent Application Laid-Open No. 4-22358 is such that light emitted from a compact LCD passes through a half mirror, and thereafter is imaged on a compact camera. On the other hand, the image pickup optical system is such that the light of the external world passes through a plane half mirror, and thereafter is imaged on the compact camera. This plane half mirror is disposed at 45° with respect to the optical axis and therefore, the apparatus has tended to become bulky. Also, this apparatus has been of a construction in which eyepieces are in front of the eyeballs and therefore a see-through optical system is not realized.
Japanese Patent Application Laid-Open No. 5-303053 discloses a construction in which a see-through optical system is realized, but the optical system is complicated and the apparatus has tended to become very bulky.
HMD's which have solved these problems are proposed in Japanese Patent Application Laid-Open No. 10-239628, Applicant's Japanese Patent Application Laid-Open No. 11-174367, Japanese Patent Application Laid-Open No. 2000-75240, etc.
Each of the compound display apparatuses proposed in these publications uses two prism-shaped optical elements (free curved surface prism) having its so-called free curved surface having different power depending on the azimuth angle disposed appropriately in both of the display optical system and the image pickup optical system, and uses the joined surface of the both free curved surface prisms as optical path separating means such as a half mirror to thereby realize a compact compound display apparatus.
SUMMARY OF THE INVENTION
It is an object of the present invention to further improve the optical system proposed in the above-mentioned publications, and appropriately construct the free curved surface prisms (optical elements) of the display optical system and image pickup optical system and an imaging optical system to thereby provide an optical element which is compact and thin in the direction of the optical axis of the eyeball and suitable for a wider angle of field and a compound display apparatus using the same.
It is another object of the present invention to appropriately set the construction of a display optical system having a plurality of eccentric reflecting surfaces for directing a beam from display means such as a liquid crystal display (LCD) to an observer's eyeball and the construction of an image pickup optical system for imaging the image information of the external world on the surface of an image pickup element such as a CCD to thereby provide a compound display apparatus which is generally downsized and yet enables the image information of the both optical systems to be observed and imaged in a good state.
It is still another object of the present invention to provide a compound display apparatus including a see-through optical system which also enables the image information of the external world to be observed at the same time.
To solve the above noted problems, the optical element of the present invention is an optical element having on the same medium an incidence surface, an emergence surface, and a plurality of eccentric reflecting surfaces eccentric relative to a reference ray Ri and having power, at least one of the plurality of eccentric reflecting surfaces being a dual purpose surface used as a transmitting surface and reflecting surface, wherein a beam incident from the incidence surface is reflected by the plurality of eccentric reflecting surfaces to thereby fold an optical path and is caused to emerge from the emergence surface, characterized in that the meridional section composite power of the optical element is negative.
In the above-described optical element, at least one of the plurality of eccentric reflecting surfaces may be a rotation-asymmetrical surface.
Also, in the above-described optical element, the emergence surface may be a rotation-asymmetrical surface.
Also, in the above-described optical element, all of the incidence surface, the emergence surface and the plurality of eccentric reflecting surface may be rotation-asymmetrical surfaces.
Also, in the above-described optical element, design may be made such that the local meridional section focal length f
ypout
and local sagittal section focal length f
xpout
of the emergence surface and the meridional section composite focal length f
yp
and sagittal section composite focal length f
xp
of the optical element satisfy
|f
yp
/f
ypout
|<2 (1)
|f
xp
/f
xpout
|<2. (2)
Also, in the above-described optical element, the emergence surface may have negative power.
Also, to solve the above-noted problems, the optical element of the present invention is an optical element having on the same medium an incidence surface, an emergence surface and a plurality of eccentric reflecting surfaces eccentric relative to a reference ray Ri and having power, at least one of the plurality of eccentric reflecting surfaces being a dual purpose surface used as a transmitting surface and reflecting surface, wherein a beam incident from the incidence surface is reflected by the plurality of eccentric reflecting surfaces to thereby fold an optical path and is caused to emerge from the emergence surface, characterized in that at least one of the plurality of eccentric reflecting surfaces is a rotation-asymmetrical surface, and design is made such that the local meridional section focal length f
ypout
and local sagittal section focal length f
xpout
of the emergence surface and the meridional section composite focal length f
yp
and sagittal section composite focal length f
xp
of the optical element satisfy
|f
yp
/f
ypout
|<2 (1′)
|f
xp
/f
xpout
|<2. (2′)
A compound lens unit may have at least one rota
Canon Kabushiki Kaisha
Dinh Jack
Epps Georgia
Fitzpatrick ,Cella, Harper & Scinto
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