US Patent 7808728 Lens barrel and image pickup apparatus

A lens barrel that can be reduced in size and improve drive accuracy. A first cylindrical member is fixed. A rotatable second cylindrical member cam-engages with the first cylindrical member so as to move in an axial direction of an axial center. A third cylindrical member engaging with the first cylindrical member so as not to rotate can move in the axial direction by the rotation of the second cylindrical member. A fourth cylindrical member cam-engaging with the third cylindrical member engages with the second cylindrical member so as to move in the axial direction by following the rotation of the second cylindrical member. A lens holding member engaging with the third cylindrical member so as not to rotate relative to the third cylindrical member can move in the axial direction by cam-engaging with the fourth cylindrical member.