Optical: systems and elements – Single channel simultaneously to or from plural channels
Reexamination Certificate
1999-10-18
2001-06-19
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
C359S691000, C359S640000
Reexamination Certificate
active
06249383
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present application is based on Application No. 10-297931 filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a taking optical system for cameras, and specifically relates to a taking optical system having an image-splitting image sensing unit for sensing divisions or parts of an image formed by an exchangeable lens.
2. Description of Related Art
In conjunction with the popularization of personal computers in recent years, digital still cameras for taking images which are easily stored on floppy disks and the like have become widely used. With the increasing popularity of digital still cameras, there has been demand for enlargement of the photographic range, and concomitant demand for photographic lenses of various specifications. In the field of recording images on silver salt film, single lens reflex cameras have come to use a plurality of exchangeable taking lenses (exchangeable lenses), and there has been a corresponding demand for taking lenses of various specifications.
If exchangeable lenses for single lens reflex cameras can be used with digital still cameras using an photoelectric conversion element, it is possible to respond to the demand for such photographic lenses. One specific method, for example, arranges a direct photoelectric conversion element on the image forming plane of an exchangeable lens. Japanese Laid-Open Patent Application Nos. 63-205626 and 7-253537 disclose other methods wherein a condenser lens is arranged near the image plane of an exchangeable lens, and a relay optical system is provided for re-forming an image formed by the exchangeable lens.
In such methods which arrange a direct photoelectric conversion element on the image forming plane of an exchangeable lens, an extremely large photoelectric conversion element having a large number of pixels is required to obtain the full optical capabilities of the exchangeable lens by having a screen size similar to that of silver salt film. Such a large photoelectric conversion element is prohibitively expensive and difficult to apply to consumer products.
The constructions disclosed in Japanese Laid-Open Patent Application Nos. 63-205626 and 7-253537 are disadvantageous inasmuch as the taking optical system is greatly enlarged by the inposition of a relay optical system so as to re-form the image formed by the exchangeable lens.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved taking optical system for cameras.
Another object of the present invention is to provide a compact taking optical system for cameras capable of using exchangeable lenses, and which is suitable for producing high quality images.
These objects are attained by a taking optical system comprising a main optical system for forming an object image, and an image splitting unit for dividing an image without re-forming the image formed by the main optical system, wherein the image splitting unit comprises sequentially from the object side a performance correcting positive lens and a split prism, and satisfies the following conditional equation:
−0.25<&phgr;h×Ys<0.25
0.8<&bgr;h<1.2
where &phgr;h represents the optical power of the performance enhancing lens, Ys represents the maximum image height by the image-splitting unit, and &bgr;h represents the transverse magnification of the performance correcting lens.
REFERENCES:
patent: 4867549 (1989-09-01), Sekine
patent: 5404247 (1995-04-01), Cobb et al.
patent: 5680249 (1997-10-01), Ishikawa et al.
patent: 5703716 (1997-12-01), Furuta
patent: 6101043 (2000-08-01), Kohno et al.
patent: 61-210312 (1986-09-01), None
patent: 63-205626 (1988-08-01), None
patent: 7-253537 (1995-10-01), None
patent: 8-114742 (1996-05-01), None
Burns Doane , Swecker, Mathis LLP
Epps Georgia
Minolta Co. , Ltd.
Thompson Tim
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