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:
Jun. 16, 1998
Filed:
May. 14, 1996
Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
An image magnification control device for a camera having a photographic lens. The image magnification control device includes a first detector that functions to detect a focal length 'f0' of the photographic lens. A distance 'X0' between a rear focal point of the photographic lens and an image taking plane of the camera is then determined based on a delivery-amount of a focusing lens of the photographic lens and the detected focal length 'f0'. A second detector detects a defocusing amount 'dx' by analyzing a light passed through the photographic lens, in which the defocusing amount 'dx' represents a displacement of an image formed by the photographic lens from the image taking plane. An image magnification 'm0' is determined based on a formula 'm0=X0/f0', while a control focal length 'f1' is calculated based on a formula 'f1=(f).sup.2 .multidot.m0)/(X0+dx)'. The focal length of the photographic lens is thus controlled so as to meet the control focal length 'f1'.