Patent ID: 6084719
Filing Date: 2000-07-04
Classification: G02B

Abstract:
A projection lens for use in a projection apparatus in which a conjugate distance between an original picture and a screen onto which to project the original picture is substantially fixed, said projection lens comprising, in order from the screen side, a first lens unit of negative refractive power and a second lens unit of positive refractive power, wherein, when a magnification of projection is shifted from a higher magnification to a lower magnification, said first lens unit remains stationary and said second lens unit moves toward the screen side to change a focal length, and said projection lens satisfying the following condition:0.85<L/fr<1.0where fr is an overall focal length in a wide-angle end of lenses which lie nearer the original picture than a stop, and L is a distance from said stop to a front principal point of the whole lenses which lie nearer the original picture than said stop.