Patent ID: 6115194
Filing Date: 2000-09-05
Classification: G02B

Abstract:
A projection lens having one side that is an enlarging side, and another side that is a reducing side, said projection lens having no more than nine lens elements of positive of negative refractive power comprising, in order from the enlarging side of said projection lens:a first lens group of positive refractive power;a second lens group of negative refractive power;a third lens group of positive refractive power and including a negative lens element and a positive lens element, in that order;a fourth lens group of negative refractive power and including a negative lens element and a positive lens element, in that order;a fifth lens group of positive refractive power;and a sixth lens group of positive refractive power;whereinthere are no intervening lens elements between the enlarging side and said sixth lens group other than the first through fifth lens groups, andsaid projection lens is structured so that, on the reducing side, a maximum angle formed by a principal ray relative to the optical axis is 2.5.degree. or less, and the following condition is satisfied0.40<F/F.sub.56 <1.4where:F is the focal length of the projection lens, andF.sub.56 is the composite focal length of the fifth lens group and sixth lens group.