Patent ID: 7295389
Filing Date: 2007-11-13
Classification: G02B

Abstract:
1. A lens barrel comprising: a lens group that conducts light from a subject; a lens shell that holds the lens group; a string-formed shape memory alloy element that moves the lens shell in a direction of an optical axis; and a pair of guide shafts formed approximately in parallel to the optical axis of the lens group, wherein the lens shell is integrally formed with a cylindrical portion through which one of the guide shafts penetrates, wherein the guide shafts guide movement of the lens shell; the string-formed shape memory alloy element contacts with a portion of the lens-shell at an approximately central portion of the alloy element; both ends of the alloy element are fixed at respective positions, wherein a line connecting the optical axis of the lens group and a center of the cylindrical portion is between the positions; and a combination of expansion or shrinkage of the string-formed shape memory alloy element and the guidance by the guide shafts moves the portion of the lens shell in contact with the string-formed shape memory alloy element approximately parallel to the optical axis to move the lens shell approximately in the direction of the optical axis.