Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2000-03-07
2001-08-21
Lester, Evelyn A (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S676000, C359S684000, C359S685000, C359S686000, C359S714000, C359S765000
Reexamination Certificate
active
06278559
ABSTRACT:
BACKGROUND OF THE INVENTION
A compact and lightweight zoom lens with high performance has been increasingly required for broadcasting and business purposes. Since high definition television broadcasting is about to proliferate, there is an urgent need for a zoom lens of practical size and weight which has high performance characteristics. Conventional zoom lenses often have many lens elements in order to attain a high performance, so they tend to be large and heavy. It has been difficult for these prior art lenses to maintain high performance imaging over the entire range of zoom from the wide-angle end to the telephoto end, while simultaneously allowing the subject distance to range from nearby to infinity. Thus, there is a need for a zoom lens which solves these two problems, while simultaneously providing a compact and lightweight zoom lens.
The assignee of the present invention has previously disclosed a zoom lens in Japanese Laid Open Patent Application H10-31157 in order to resolve these problems. However, a more lightweight and compact zoom lens is now required.
BRIEF SUMMARY OF THE INVENTION
This invention concerns a zoom lens, for use especially in television cameras for broadcasting or business purposes, where high performance is required. A first object of the present invention is to minimize the shift in image surface when the focal length is varied from the wide-angle to the telephoto end. A second object of the invention is to minimize the shift in image surface when the object is moved from the near to far position of focus. A third object of the invention is to provide a compact zoom lens. A fourth object of the invention is to provide a lightweight zoom lens.
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patent: 4874231 (1989-10-01), Aono
patent: 5666230 (1997-09-01), Tatsuno
patent: 5677792 (1997-10-01), Hamano
patent: 5808809 (1998-09-01), Yahagi
patent: 5856885 (1999-01-01), Yamamoto
patent: 5898525 (1999-04-01), Suzuki
patent: 5986820 (1999-11-01), Usui et al.
patent: 5995296 (1999-11-01), Usui
patent: 6002527 (1999-12-01), Ohtake
patent: 6055114 (2000-04-01), Ohtake
patent: 61-39016 (1986-02-01), None
patent: 10-31157 (1998-02-01), None
Arnold Bruce Y.
Fuji Photo Optical Co., Ltd.
International Arnold
Lester Evelyn A
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