| 摘要 |
PURPOSE:To maintain the drive torque of a pulse motor substantially constant by varying the time constant of a counterelectromotive force absorber in a pulse motor. CONSTITUTION:In a circuit having resistors R1, R2 and a diode D for absorbing counterelectromotive forces produced at exciting coils phi1-phi4 of a pulse motor, a switch K is provided in parallel with a resistor R1, and when a sub-scanning line density is 3.85 pieces/mm., the switch K is opened, while when the sub-scanning line density is 7.7 pieces/mm., the switch K is closed to increase the time constant of the counterelectromotive force absorber when the sub-scanning line density is increased, thereby maintaining the drive torque of the pulse motor substantially constant even if the sub-scanning line density is switched-over. |
