Patent ID: 6853500

Claim:
A retracting mechanism of a zoom lens barrel including a first lens group, a second lens group and a third lens group, in that order from an object side, wherein said first lens group and said third lens group are integrally moved along an optical axis thereof during a zooming operation, and wherein at least one of said first lens group and said third lens group is moved relative to the other to reduce a distance therebetween when said zoom lens barrel is retracted, said retracting mechanism comprising: a first lens group moving ring which is linearly guided along said optical axis, and supports said first lens group; a second lens group moving ring which is linearly guided along said optical axis, and supports said second lens group; a third lens group moving ring which is linearly guided along said optical axis, and supports said third lens group, said third lens group moving ring being allowed to freely approach said first lens group moving ring while being prevented from moving away from said first lens group moving ring beyond a moving limit relative to said first lens group moving ring; a cam mechanism for moving said first lens group moving ring and said second lens group moving ring in respective moving manners independent of each other along said optical axis; a biasing device for biasing said third lens group moving ring in a direction away from said first lens group moving ring; a linear guide through-slot formed on said second lens group moving ring to be elongated in a direction parallel to said optical axis; a first linear guide projection formed on said first lens group moving ring to be engaged in said linear guide through-slot from outside said second lens group moving ring, said first linear guide projection including a hanging groove formed along a substantially center thereof and elongated in a direction parallel to said optical axis, a rear end of said hanging groove being closed; a second linear guide projection formed on said third lens group moving ring to be engaged in said linear guide through-slot from inside said second lens group moving ring; and a linear moving key projecting from a front end of said second linear guide projection to be engaged in said hanging groove, wherein a rear moving limit of said third lens group moving ring relative to said first lens group moving ring is determined by contact of said linear moving key with said closed rear end of said hanging groove.