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:
May. 16, 1989
Filed:
Jul. 21, 1988
Kazuo Yamakawa, Osaka, JP;
Kazuhito Aoki, Osaka, JP;
Minolta Camera Kabushiki Kaisha, Osaka, JP;
Abstract
The present invention provides a lens system for projecting to a screen a video image formed on a face plate of a cathode ray tube. The lens system comprises, from the screen side to the tube side: a first positive lens unit; a second positive lens unit; a third negative lens unit having a screen side surface convex to the screen side; a fourth lens unit of bi-convex lens; and a fifth negative lens unit having a screen side surface concave to the screen side, at least the fourth lens unit being made of glass material, wherein the lens system includes at least one aspheric surface and fulfills the following conditions: ##EQU1## wherein; f represents the focal length of the whole lens system; f.sub.1 represents the focal length of the first positive lens unit; f.sub.2 represents the focal length of the second positive lens unit; f.sub.3 represents the focal length of the third negative lens unit; and .nu..sub.3 represents the Abbe number of the third negative lens unit.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile