Patent ID: 7428377
Filing Date: 2008-09-23
Classification: G02B

Abstract:
1. A focusing drive apparatus comprising: a focusing lens group disposed so as to be movable frontward and rearward in an optical axis direction for focusing of a picture taking lens; a motor for driving the focusing lens group; a motive power transmission mechanism changed between an engaged state in which motive power of the motor can be transmitted to the focusing lens group and a disengaged state in which motive power of the motor cannot be transmitted to the focusing lens group; an AF device which moves the focusing lens group to an in-focus position by means of the motor based on a contrast in an image of a subject taken through a picture taking optical system; a manual operation device which enables the focusing lens group to be moved by a manual operating force; a determination device being configured to determine whether a present focusing condition is an AF-able condition in which the focusing lens group can be moved to the in-focus position by the AF device or an AF-unable condition in which the focusing lens group cannot be moved to the in-focus position by the AF device; and a change control device being configured to set, the motive power transmission mechanism in the engaged state to enable the focusing lens group to be moved to the in-focus position by the AF device when the determination device determines that the present focusing condition is the AF-able condition, and, being configured to set the motive power transmission mechanism in the disengaged state to reduce the necessary manual operating force for moving the focusing lens group by means of the manual operation device when the determination device determines that the present focusing condition is the AF-unable condition.