Patent ID: 8270074
Filing Date: 2012-09-18
Classification: G02B,G09B

Abstract:
1. A magnified-projection optical system for magnified-projection of an image outputted from a display element onto a screen comprising: a projection optical system, a relay optical system and a display element, which are arranged sequentially along an optical axis in that order as viewed from a screen side, wherein the relay optical system forms a primary image of the image outputted from the display element, and the projection optical system provides magnified-projection of the primary image formed by the relay optical system onto the screen and includes a negative group having a negative optical power and a positive group having a positive optical power arranged sequentially in that order as viewed from the screen; wherein the negative group includes: at least one negative meniscus lens arranged on the screen side; and at least one negative lens; wherein the projection optical system and the relay optical system satisfy the following conditional expressions (1) and (2): where Fb is a back focus of an entire optical system including the projection optical system and the relay optical system, F is a focal distance of the entire optical system, and Fp is a focal distance of the projection optical system.