Patent ID: 7801434
Filing Date: 2010-09-21
Classification: G02B,H04N

Abstract:
1. A focus controller configured to control focus of an optical element, said focus controller comprising: a sensor configured to detect an image formed by the optical element and to output an image signal; a focus state detector configured to detect a focus state based on a contrast value of the image obtained from the image signal output from the sensor; and a driving mechanism configured to move the optical element or the sensor relative to the other in controlling the focus, wherein the driving mechanism includes: a motor that includes a rotor having a magnet, and a stator having a coil configured to provide a rotational force to the magnet; a position sensor configured to detect a position of the rotor in the motor; and a driving controller configured to select a first driving operation in a case of a feedback energization switching mode or a second driving operation in a case of a step mode, said first driving operation being configured to switch an energization state of the coil in accordance with an output of the position sensor, said second driving operation being configured to switch the energization state of the coil in accordance with a determined time interval, said feedback energization switching mode being configured to move the optical element in a predetermined direction at a first speed while detecting the focus state using the focus state detector, and said step mode being configured to reciprocate the optical element at a predetermined period at a second speed smaller than the first speed in an optical-axis direction while detecting the focus state.