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:
Sep. 06, 2022
Filed:
Sep. 18, 2019
Seiko Epson Corporation, Tokyo, JP;
Koji Shiokawa, Azumino, JP;
Toshihiko Sakai, Matsumoto, JP;
Seiko Epson Corporation, Tokyo, JP;
Abstract
A projection system has a zooming function and is configured that light rays from a telecentric system enter. The projection system is formed of seven lens groups. The first and seventh lens groups are fixed when the projection magnification is changed, and the second, third, fourth, fifth, and the sixth lens groups move along the optical axis when the projection magnification is changed. The second lens group is formed of one positive lens. The third lens group is formed of one positive lens. The fourth lens group is formed of one or two positive lenses and one negative lens having the center of curvature located at the magnifying side. The fifth lens group is formed of one negative lens having a magnifying-side aspheric surface and a demagnifying-side aspheric surface with each of the surfaces having the center of curvature located at the demagnifying side.