| 摘要 |
PURPOSE:To automatically attain initialization by providing a switching means bringing the exciting coil of a stepping motor into the closing state at power supply interruption. CONSTITUTION:When a main power supply is interrupted, the coil of an electro magnetic relay 3 is interrupted, the contact of the electromagnetic relay 3 is closed, the terminals of coils 1, 2 of the stepping motor SM are short-circuited and the driving of a rotor of the stepping motor SM is blocked. In the stepping motor, the rotor having a permanent magnet is moved stepwise by using plural exciting coils, and when the rotor receives an external torque when the terminals of the exciting coils are short-circuited, the inverse electromotive force is generated to the closed circuits of the short-circuited coils 1, 2 to disturb the drive of the rotor. Thus, no troublesome operation is required and the mag netic head seeking mechanism is braked to protect the magnetic head and other devices and the automatic initialization is applied even without loading the magnetic disk.
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