The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 28, 1976
Filed:
Feb. 24, 1975
Keiichi Sakaguchi, Yokohama, J;
Noritsugu Hirata, Yokohama, J;
Canon Kabushiki Kaisha, Tokyo, J;
Abstract
A zoom lens structure for use with an optical instrument comprises a zooming optical system movable along the optical axis thereof and including a magnifying system and a correcting system; support frames for holding the zooming optical system; a plurality of guide shafts fitted in the support frames of the zooming optical system to cause sliding of the support frames; a frame member for holding the guide shafts at the opposite ends thereof and surrounding the zooming optical system; a fucusing optical system; a holder frame for permitting the focusing optical system to be moved along the optical axis independently of the zooming optical system; and a mechanism using a cam to drive the holder frame. Within the frame member surrounding the zooming optical system, a beam splitter for splitting an object light beam to derive a viewfinder light beam is interposed between the portion of the frame member remote from an object to be photographed and the zooming system. The side wall of the frame member is formed with an opening for passing therethrough the viewfinder light beam. Thus, the lengths over which the zooming optical system holder frames and the guide shafts are fitted together can be increased to enhance the zooming accuracy.