Patent ID: 8248709
Filing Date: 2012-08-21
Classification: G02B

Abstract:
1. A zoom lens barrel including a plurality of stages of hollow cylindrical units that are extended in a direction of an optical axis of the zoom lens barrel, comprising: a first hollow cylindrical unit configured to hold a first lens group; a second hollow cylindrical unit which is lower than said first hollow cylindrical unit by at least two stages; a holding member supported by said second hollow cylindrical unit and configured to hold a second lens group; and an urging unit configured to urge said holding member toward the first lens group, wherein a cam follower is formed on said holding member, and a cam portion for engagement with said cam follower is formed on said second hollow cylindrical unit, and wherein in a shooting region, said cam portion has two cam surfaces on each of an object side and an image-forming surface side, while having, at a retracted position, one cam surface on the object side, wherein at said retracted position, said holding member is urged by said urging unit, whereby said cam portion is brought into contact with said cam follower via the one cam surface on the object side, whereas in a shooting region, said cam portion is in contact with said cam follower via the two cam surfaces on each of the object side and the image-forming surface side, and wherein said cam follower in engagement with said cam portion moves in the optical axis direction in accordance with rotation of said second hollow cylindrical unit to thereby move the second lens group toward the first lens group.