Patent ID: 6779897
Filing Date: 2004-08-24
Classification: G02B,G03B

Abstract:
An oblique projection optical system for leading rays of light from a display surface on which an image is displayed to a projection surface in such a way that a ray of light from a center of the display surface is obliquely incident on the projection surface in order to project a magnified image of the image displayed on the display surface onto the projection surface, the oblique projection optical system including a plurality of reflecting surfaces having a power,wherein at least two of the reflecting surfaces having a power have a free-form curved surface, and, of all the reflecting surfaces having a power, the one closest to the projection surface has a negative power and at least one of the others has a positive power; and wherein the display surface has a smaller dimension in a height direction than in a width direction, the reflecting surfaces having a power each reflect the rays of light from the display surface in such a way as to deflect the rays of light in the height direction of the display surface, a pupil plane is located between the one of the reflecting surfaces having a power that is second-closest to the display surface and the display surface, and the following conditions are fulfilled: Fnoy&gE;Fnoz, Fnoy&lE;4.5, and Fnoz&lE;4.0, where Fnoy represents an f-number in a direction corresponding to the height direction of the display surface, and Fnoz represents an f-number in a direction corresponding to the width direction of the display surface.