Erasing system of magnetic disk

Abstract

Abstract PURPOSE:To erase from low frequency component to high frequency component without lowering rotational frequency of a magnetic disk by setting initial frequency in the frequency band of a record signal and recording alternating signals that change gradually until becoming higher than upper limit frequency and erasing. CONSTITUTION:When erasing a recorded still picture, a switch 9 is changed, and a signal of a sweep generator 8 is supplied to a magnetic head 3 through a recording amplifier 6. The sweep generator 8 is made variable by a counter 7 that counts rotational frequency of a motor 2, and frequency of an erasing signal increases with time. In this initial stage of sweep, recording magnetic field of the magnetic disk 1 which is in low band frequency area is rewritten and erased by initial frequency of sweep. As the sweep frequency becomes higher, the high band recording magnetic field is successively rewritten and erased by the sweep frequency. Finally, only the recording magnetic field due to final frequency set outside of recording frequency band remains, and consequently, the recorded still picture information is erased.

Inventors

• 👤 Etsuro Saito
• 👤 悦郎 斉藤

Bibliographic Details