Birch, Stewart, Kolasch & Birch, LLP
Projection zoom lens and projection-type display device
A negative first group G1 is fixed when a power of the projection zoom lens varies and has a focusing function. A positive second group G2, a positive or negative third group G3, a positive fourth group G4 and a positive or negative group G5 move with a mutual relationship. A sixth group G6 functions as a relay lens. The fifth group G5 includes a cemented lens formed by cementing a negative meniscus lens L10 having a convex surface directed to the magnification side, a negative lens L11 and a positive lens L12 in order from a magnification side, and a positive lens L13 having a convex surface directed to a reduction side. Also, an expression |F5|/F>4.5 is satisfied where F denotes a focal length of the projection zoom lens at a wide-angle end and F5 denotes a focal length of the fifth group.
Fujinon Corporation
G
G02B
inventional
Hiroshi Kimiaki
Yamada Nakazawa