| 摘要 |
PURPOSE:To protect a motor and its driving circuit by providing a 1st overcurrent detecting means which detects the overcurrent of a momentary current of the driving motor and a 2nd overcurrent detecting means which detects an overcurrent to a mean current, and stopping the driving motor through the operation of both overcurrent detecting means. CONSTITUTION:A controller 10 turns on transistors (TR) 2 and 5 and turns off TRs 3 and 4 so as to rotate a DC motor 6 forward (CW). Further, the TRs 3 and 4 are turned on and the TRs 2 and 5 are turned off so as to rotate the motor backward (CCW). Therefore, whichever direction the DC motor rotates, a current conducted through the DC motor 6 is conducted through a resistance 7, so it can be detected. When the current I conducted through the DC motor 6 exceeds a maximum momentary permissible current I2, a CPU 12 checks an overcurrent detection input from an interface 11 at a sampling period and stops the DC motor 6 is there is the input. Further, the output of a comparator 9 turns off the DC motor 6 when a current exceeding a continuous rated permissible current I1 is conducted for T seconds. Consequently, the motor can be protected against the maximum momentary current and continuous rate current.
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