Patent ID: 7986468
Filing Date: 2011-07-26
Classification: G03B

Abstract:
1. A lens barrel comprising: an imaging optical system; a tube configured to contain the imaging optical system; a movable holder configured to hold a lens included in the imaging optical system in the tube in such a way that the lens is movable along a direction of an optical axis of the imaging optical system; a sensor unit configured to output a sinusoidal cyclic detection signal responsive to the movement of said holder, said cyclic detection signal having a peak value that changes depending on a movement amount of the holder; a memory unit configured to store a relationship between peak values of the detection signal and a position of the holder in the direction of the optical axis in advance; and an arithmetic processor configured to calculate a position of the holder in the direction of the optical axis from a peak value of a detection signal detected by the sensor unit in movement of the holder based on the relationship stored in the memory unit.