Patent ID: 7970273
Filing Date: 2011-06-28
Classification: G03B

Abstract:
1. A diaphragm control apparatus incorporated in a camera body, to which an interchangeable lens provided with a diaphragm apparatus is detachably attached, said diaphragm apparatus including a diaphragm operatively-associated rod for driving an adjustable diaphragm to open and shut said adjustable diaphragm, and said diaphragm control apparatus including a slider that is driven to move said diaphragm operatively-associated rod, said diaphragm control apparatus comprising: a diaphragm control mechanism including a stepping motor and a lead screw which is driven to rotate by said stepping motor, wherein said slider is moved via rotation of said lead screw; a position detector, which detects a position of said slider; and a controller, which controls an excitation pattern of said stepping motor, wherein said slider is biased to move toward an initial position by a resilient biaser, wherein, when said stepping motor is in a free state with said interchangeable lens attached to said camera body, said slider allows said diaphragm operatively-associated rod to move to said initial position by a biasing force of said resilient biaser that biases said slider toward said initial position while rotating said lead screw and said stepping motor, wherein said controller detects a position of said slider as an origin position thereof via said position detector when said stepping motor is in said free state, wherein said controller drives said stepping motor stepwise by a predetermined number of steps in a direction to move said slider away from said origin position against said biasing force of said resilient biaser, and thereafter drives said stepping motor stepwise in a direction to move said slider toward said origin position while detecting a position of said slider via said position detector, and wherein said controller performs an origin-position initialization process which sets an initial excitation pattern of said stepping motor upon a distance from said detected position of said slider to said origin position becoming less than a moving distance of said slider for one step of said stepping motor.