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:
Feb. 22, 2000
Filed:
Nov. 25, 1997
Katsuhiro Takamoto, Sakai, JP;
Masakuni Tai, Machida, JP;
Minolta Co., Ltd., Osaka, JP;
Abstract
A variable magnification optical system for projecting images from a small-sized, high-resolution display device consists of, from the projection side, a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a negative optical power, and a fourth lens unit having a positive optical power and kept in a fixed position during magnification adjustment. The optical system achieves magnification adjustment by moving at least the second and third lens units along the optical axis, and has at least one negative lens element in the second lens unit, at least one negative lens element in the third lens unit, and at least one positive lens element in the fourth lens unit made of lens materials having predetermined anomalous dispersions and predetermined Abbe numbers.