Projection zoom lens system and projector
AssigneeNittoh Kogaku K.K.
InventorsShuji Narimatsu, Akira Sawamoto
Life of this patent
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Abstract
A projection zoom lens system according to the present invention has a substantially telecentric incidence side and comprises a plurality of lens groups for behaving differently between a wide-angle end and a telephoto end, wherein at least one of two surfaces of a lens included in a first lens group located closest to a screen side has an aspheric surface. Since the lens closest to the screen has the largest diameter and the density of light rays becomes smallest among the lenses, it is possible to design the aspheric surface for correcting properly the light rays and reduce the correcting loads of the other lens groups constituting the projection zoom lens system so as to provide the compact and high performance zoom lens system.
Claims9
A projection zoom lens system having a substantially telecentric incidence side, comprising a plurality of lens groups for behaving differently between a wide-angle end and a telephoto end, wherein at least one of two surfaces of a lens included in a first lens group located closest to a screen side has an aspheric surface, and wherein the plurality of lens groups are the first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power, arranged in this order from the screen side, whereby zooming is carried out by fixing the first and fifth lens groups and moving the second, third and fourth lens groups.
Dependencies are inferred from the claim text.