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:
Jan. 21, 2020
Filed:
Dec. 04, 2017
Seiko Epson Corporation, Tokyo, JP;
Koji Shiokawa, Azumino, JP;
Nobutaka Minefuji, Azumino, JP;
SEIKO EPSON CORPORATION, Tokyo, JP;
Abstract
A projection optical system includes a first lens unit adapted to make a enlargement-side imaging surface and an intermediate image conjugate with each other, a second lens unit adapted to make the intermediate image and a reduction-side imaging surface conjugate with each other. The first lens unit has positive power, and the second lens unit has negative power. Defining a focal distance of the first lens unit as fU, a focal distance of the second lens unit as fU, a total lens length of the first lens unit as LLU, and a total lens length of the second lens unit as LLU, the following expression (1) and expression (2) are satisfied:−0.3<1/2<−0.005  (1)0.5<1/2<0.9  (2).