Patent ID: 7593053
Filing Date: 2009-09-22
Classification: G02B,G03B,H04N

Abstract:
1. An autofocus device comprising: a lens-driving unit that drives a lens; a focal-point-position-detecting unit that detects a position of a focal point of the lens; a distance measurement sensor that measures a distance to an object; and a control unit that performs a focus operation to control the lens-driving unit to drive the lens so that the position of the focal point of the lens detected by the focal-point-detecting unit is set to an in-focus position, wherein, when a restart condition of the focus operation has not yet been satisfied after the position of the focal point of the lens is set to the in-focus position, the control unit determines a switch of focusing on objects based on the position of the focal point of the lens detected by the focal-point-detecting unit and a measured distance result by the distance measurement sensor, and wherein the control unit restarts the focus operation based on a determination result of the switch of focusing on objects and drives the lens so that the position of the focal point of the lens is set to an in-focus position based on a measured distance result by the distance measurement sensor, wherein the control unit determines whether a determination period of time for determination of the switch lasts longer than a reference period of time for the switch of focusing on objects and restarts the focus operation when the determination period of time lasts longer than the reference period of time, and wherein the control unit changes the reference period of time based on any one of brightness of an object to be imaged and measuring time of the distance measurement sensor.