| 摘要 |
PROBLEM TO BE SOLVED: To suppress an increase in a circuit scale due to complicated calculation and ensure high speed response in PWM driving control of a DC motor.SOLUTION: If a DC motor is PWM-controlled so as to feed roll paper or apply a back tension by the DC motor, the following control is exercised. That is, a current for driving the DC motor is detected, and a value of the current is compared with a target value for the PWM control. Next, using a preset clock, values indicative of the comparison result are counted for a cycle of a PWM control signal, an output tendency of the comparison result is studied on the basis of an obtained count value per cycle of the PWM control signal and encoded as a code. Values of the code are stored by as much as preset cycles of the PWM control signal in a storage unit. The code values stored in both a first period and a second period longer than the first period are examined as a previous tendency of the PWM control, and the PWM control signal is adjusted. |
