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. 19, 2023
Filed:
Oct. 08, 2021
Kenji Miya, Iwate, JP;
Kenji Miya, Iwate, JP;
RICOH INDUSTRIAL SOLUTIONS INC., Kanagawa, JP;
Abstract
A projection optical system includes a first refractive system, a reflective optical system, and a second refractive system, disposed in the stated order in a direction from the reduction side toward the enlargement side, to enlarge and project an image displayed on an image display element, onto a projection surface. A first lens group of the first refractive system forms a first intermediate image with a light beam from the image display element. A second lens group of the first refractive system forms a second intermediate image with a light beam from the first intermediate image. A light beam from the second intermediate image is reflected by the reflective optical system and is then refracted by the second refractive system. A condition (1): 1.5<Bf/f<25 is satisfied, in which f represents a focal length of the entire projection optical system and Bf represents a back focus obtained by air conversion.
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