| 摘要 |
PURPOSE:To operate a stepping motor with a high accuracy and a high resolution by making the relation between the number of steps and a motor turning angle linear. CONSTITUTION:A detected voltage Via (a detected current value) and a command voltage Vsa (a target current value) are applied to a constant current chopper circuit 2a. Since the output voltage Voa is at a low level while the Via does not reach the Vth, the motor current increases through a negative-logic motor driver 3a. At that time, the Vth is equal to the Vsa because a transistor TR becomes off. When the Via rises to the Vth due to the increase of the motor current, the motor current decreases because the Voa reverses to a high level and the Vth decreases to Vsa.R2/(R1+R2) since the TR becomes on. When the Via drops to the Vth due to the decrease of the motor current, the motor current increases again since the Voa comes back to the low level and the Vth rises to the Vsa since the TR becomes off. By this, a hysteresis DELTAVth of the Vth is Vsa.R1/(R1+R2). |
