ZOOM LENS FOR PROJECTION AND PROJECTOR

摘要

PROBLEM TO BE SOLVED: To prevent positional deviation in variable power at the time of focusing and to realize the reduction of cost and compaction. SOLUTION: A 1st lens group 23 having a focusing function is held by a holding frame 33. The frame 33 is coupled with a 1st moving frame 30 through a helicoid. The frame 30 moves between a housing position where the frame 33 is withdrawn in a lens barrel when a cam barrel 22 is rotated to a non-use position and a projecting position where the frame 33 projects to a screen 18 side when the cam barrel 22 is rotated to a variable power area. In the case of focusing, the frame 33 is rotated. Thus, the frame 33 moves following the lead of the helicoid 33a with respect to the frame 30. A cam 38 for the frame 30 provided in the cam barrel 22 is formed in a circular arc-shaped locus in a direction orthogonal to an optical axis 6a within the rotating range of the cam barrel 22 corresponding to a zoom area. Thus, the cam barrel 22 is not rotated even when the frame 33 is rotated in the case of focusing. Then, an inexpensive and compact projector is provided because of adopting manual focusing.