JPS6448205A - Magnetic disk driving device - Google Patents

Abstract

PURPOSE:To surely erase the desired part of a magnetic disk and to avert the deterioration in C/N (carrier to noise ratio) of the reading out signal of the signal written after the erasing by the erased residual magnetization pattern by controlling the timing to supply an erasing signal. CONSTITUTION:This device has a pair of magnetic heads Ha, Hb which are different in gap azimuth from each other and are commonly used for writing, reading out and erasing, an erasing signal source 21 which supplies the erasing signal and a timing control circuit 22 which controls the timing to supply the erasing signal. An index signal is extracted by the erasing timing control circuit 22 from the data read out by the magnetic head Ha and the erasing signal is supplied to erase this part at the time of erasing the data of the desired sector of tracks Ta. Since the tracks Ta are erased by the magnetic head Hb of the gap azimuth different from the recording azimuth thereof, the deterioration in the C/N of the reading out signal of the signal written afterward by the residual magnetization of the erasing pattern is obviated.