Patent ID: 6535691
Filing Date: 2003-03-18
Classification: G02B

Abstract:
A lens drive comprising:a stepper motor that can be rotated forward and reversely; motor control means for controlling driving of the stepper motor; a photographing lens for forming a subject image on predetermined image surface; lens drive means for driving the photographing lens; coupling means for coupling the stepper motor and the lens drive means, transmitting a forward operation of the stepper motor, thereby driving the photographing lens from an initial position to a focus position, and transmitting a reverse operation of the stepper motor, thereby driving the photographing lens from the focus position to the initial position; and memory means connected to said motor control means for storing control data therein so that the control data can be readable depending on an object focus position, said control data comprising individual data for each one of a plurality of object focus positions, wherein the motor control means comprises: start control means for supplying a forward pulse in a frequency band of a self-start area to the stepper motor stopping at the initial position to start forward rotation of the stepper motor; acceleration control means for increasing frequency of the forward pulse so that the forward pulse in a frequency band of a through area is supplied to the stepper motor which is placed in a forward rotation state by the start control means; constant-speed drive control means for maintaining the frequency of the forward pulse supplied to the stepper motor, which is placed in the forward rotation state in the through area by the acceleration control means, until the stepper motor, is driven to a proximity of the object focus position; deceleration control means for decreasing the frequency of the forward pulse so that the forward pulse in the frequency band of the self-start area is supplied to the stepper motor which is driven to the proximity of the object focus position by the constant-speed drive control means; and stop control means for stopping the stepper motor using the deceleration control means when the stepper motor is driven to the object focus position.