Projection zoom lens system and projector apparatus
AssigneesNittoh Kogaku K.K., In Focus Systems, Inc.
InventorsSyuji Narimatsu, Jeffrey A. Gohman
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Abstract
A projection zoom lens system of the present invention for projecting image onto a screen from a light modulator such as a DMD includes a first lens group having a negative refractive power and a second lens group having a positive refractive power arranged in this order from the screen side. An outer diameter LD of the last lens and a back focus at the wide-angle end Bfw of the projection zoom lens system satisfy the condition below. 0.3<LD/Bfw<0.5 (A). Further, at least one of surfaces of the last lens is aspheric. Therefore, even though the back focus is long and a diameter of the last lens is small, it is possible to provide a compact projector lens system having excellent optical performance with the only nine lenses arrangement.
Claims6
A projection zoom lens system for projecting an image onto a screen from a light modulator that includes a plurality of elements for changing a reflection direction of light to generate the image, said projection zoom lens system comprising a first lens group having a negative refractive power and a second lens group having a positive refractive power, arranged in this order from the side of said screen, wherein at least one of both surfaces of a last lens of said second lens group that is closest to said light modulator is aspheric, and
- wherein an outer diameter LD of said last lens and a back focus at a wide-angle end Bfw of said projection zoom lens system satisfy the following condition:
- 0.3<LD/Bfw<0.5.
Dependencies are inferred from the claim text.