Patent ID: 7391578

Claim:
A projection zoom lens system, comprising, in order from an enlargement side to a reduction side, a first lens unit of negative refracting power, a second lens unit of positive refracting power, and a third lens unit of positive refracting power, wherein: upon zooming from a wide-angle end to a telephoto end with a projected image focusing on a constant position, the first lens unit and the second lens unit move while the third lens unit remains fixed, and wherein: the third lens unit is located on the enlargement side of a light bulb, and transmits an incident light ray from an illumination optical system adapted to illuminate the light bulb and a light ray reflected from the light bulb, and wherein: the first lens unit consists of, in order from the enlargement side to the reduction side, a meniscus shaped lens convex on the enlargement side and having negative power, a lens having two aspherical surfaces, a lens of negative power, wherein an absolute value of curvature is larger on the reduction side than on the enlargement side, and a lens of positive power, wherein an absolute value of curvature is larger on the enlargement side than on the reduction side.