| 摘要 |
PURPOSE:To make the detection of the abnormal rotation of a step motor during its constant-speed rotation, by detecting the increase or decrease of the peak value of an exciting current beyond the specified range. CONSTITUTION:A transistor 4a is turned on and off by a driving signal which is input to a terminal 1a, and the base potential of a transistor 4a is varied by an operation amplifier 3a which receives a reference voltage Vref that is applied to a terminal 1b, thereby the current flowing in an exciting winding 10 is constantly controlled. At this time, a capacitor 5b is charged by the exciting current via a diode 6c. When the potential of the capacitor 5b is decreased to below a specified voltage V1 or exceeds V2, a signal 1 is output from operation amplifiers 3b and 3c. When abnormal rotation occurrs during the constant-speed rotation, wherein a gate signal 1d is input; the exciting current increases or decreases due to armature reaction, the potential of the capacitor 5b becomes <V1 or >V2, an AND circuit 8 is turned on, and the abnormal rotation can be detected. |
