Patent ID: 8363155
Filing Date: 2013-01-29
Classification: G03B,H04N

Abstract:
1. An automatic focusing apparatus for performing focus adjustment of an object image by driving a focus lens along an optical-axis direction, the automatic focusing apparatus comprising: an image pickup portion for converting an optical signal of an object image into an electric video signal by an image sensing element; an evaluating portion for calculating an evaluation value from the video signal obtained by the image pickup portion; a focus motor for driving the focus lens; an exposure controlling portion for calculating an exposure amount of the image pickup portion; a first calculating portion; and a drive controlling portion for controlling an acceleration/deceleration drive of the focus motor according to a predetermined acceleration/deceleration function, wherein the drive controlling portion accelerates the drive of the focus motor up to a target velocity and decelerates the drive of the focus motor from the target velocity after the target velocity is reached in synchronization with a synchronization signal for generating a timing of starting exposure for the optical signal of the image pickup portion, wherein the drive controlling portion is constructed in such a manner that a first acceleration/deceleration mode, in which a velocity of the focus motor is accelerated up to the target velocity and decelerated from the target velocity after the target velocity is reached in synchronization with the synchronization signal in a vertical synchronization time of the image sensing element, and a second acceleration/deceleration mode, in which the velocity of the focus motor is accelerated up to the target velocity and decelerated from the target velocity after the target velocity is reached in synchronization with the synchronization signal in a charge sweep time of the image sensing element within the vertical synchronization time of the image sensing element determined from the exposure amount calculated by the exposure controlling portion, can be selectively executed, and wherein the drive controlling portion selects the first acceleration/deceleration mode or the second acceleration/deceleration mode based on times calculated by the first calculating portion, in which the target velocity is reached in the first acceleration/deceleration mode and the second acceleration/deceleration mode, respectively, and the charge sweep time of the image sensing element.