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:
Apr. 07, 1998
Filed:
Jun. 17, 1996
Fumiaki Usui, Kawasaki, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A zoom lens device including in order of lens units from the lens unit closest to an object side of the zoom lens device to an image side of the zoom lens device, a first lens unit having a positive refractive power, a second lens unit for changing magnification and having a negative refractive power, a third lens unit for correcting changes in an image plane which occur as the magnification changes, and a fourth lens unit for forming an image. The first lens unit includes (i) a front lens subunit which is stationary during focusing and which has a positive refractive power and (ii) a rear lens subunit which is movable in order to bring an object into focus. The front lens subunit includes a negative lens and a positive lens. The rear lens subunit includes a negative lens and at least two positive lenses.