Patent ID: 8773726
Filing Date: 2014-07-08
Classification: G05B,H04N

Abstract:
1. An image forming device controlling a motor that drives a unit, the device comprising: a rate error calculator to calculate a rate error from a difference between a practical rotation rate and a target rotation rate of the motor; a position error calculator to calculate a position error from a required target rate and a time interval of a time interrupt that is generated by a central processing unit (CPU) every control cycle; a motor state controller to determine a state of the motor using the practical rotation rate, the current position, and the time interrupt; a rate commander to output the target rotation rate that is optimal for the determined state of the motor to the rate error calculator; a rate/position controller to output a control pulse to control a rotation rate and a position of the motor by applying the rate error received from the rate error calculator and the position error received from the position error calculator; an encoder to output at least two pulses that vary according to the practical rotation rate of the motor; a practical rotation rate measurer to measure the practical rotation rate using a time interval and a physical distance interval of the at least two pulses; and a current position measurer to measure the current position by counting a number of edges whenever each of the edges is generated from the at least two pulses, wherein the motor state controller operates the rate commander at time intervals when the time interrupt is generated, so as to output a target rotation rate optimal to the determined state of the motor.