| 摘要 |
PROBLEM TO BE SOLVED: To obtain a large Q value for the resonance of a head system to improve erasing efficiency by using a signal obtained by dividing or multiplying oscillation frequency of a crystal oscillation means as an erasing head driving signal. SOLUTION: When the CONT terminal drops to Lo level, operation starts. An external signal for driving the head is input from the IN terminal. The resonance frequency of a parallel resonance circuit consisting of a capacitor C2 and an inductor L2 is almost matched with the frequency of the input signal. A damping resistor of head system is added between collector and the ground of a transistor Q7. In this circuit, R10 is 1.8 kω. The signal input from the IN terminal is a rectangular waveform of 7.16 MHz. Since the oscillation frequency is no longer fluctuated, the Q value of the driving circuit and head system is raised to improve the erasing efficiency. Thereby, simultaneous erasing of four tracks can be done at a time with the wide erasing head and power saving can also be realized.
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