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US4623943A Head positioning apparatus using a DC motor 失效
头定位装置使用直流电机

Head positioning apparatus using a DC motor
摘要:
In a head position control apparatus, a magnetic pole disc mounted on a DC motor has a plurality of opposite magnetic poles arranged on its circumference in a predetermined relationship with tracks on a floppy disk. A sensor located close to the pole disc generates a pulse signal having pulses corresponding to the tracks and a voltage representing the actual speed of the motor. The pulses are counted in an incremental or a decremental mode. The difference between a track position indicating command signal from a keyboard and the pulse count is detected for deriving a direction signal which indicates the direction of the head and determines the count mode, a speed reference variable according to a predetermined transfer function and a switching signal when the difference reduces below a certain limit. A speed control signal is generated representing the difference between the speed reference and the actual speed of the motor. A position control signal is generated representing the difference between the amplitude of the pulse signal and a reference voltage. In response to the switching signal one of the control signals is applied to a polarity inverter for inverting or noninverting its polarity depending on the direction signal and on its amplitude relative to the reference voltage.
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