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. 25, 2020
Filed:
Nov. 26, 2018
Seiko Epson Corporation, Tokyo, JP;
Koji Shiokawa, Azumino, JP;
SEIKO EPSON CORPORATION, Tokyo, JP;
Abstract
A projection optical system includes a first lens unit and a second lens unit interposing an intermediate image therebetween. The first lens unit includes two aspherical lenses (a first lens unit first lens and a first lens unit ninth lens), and a first lens unit cemented lens. The projection optical system satisfies the following Conditional Expressions (1) and (2) when the number of lens elements of the first lens unit and the number of lens elements of the second lens unit are set to be Num1 and Num2, respectively. In addition, refractive indexes and Abbe numbers of three lenses constituting the first lens unit cemented lens satisfy a predetermined conditional expression.Num2≤7  (1)1.5≤Num1/Num2≤2.5  (2)