PROTECTION SYSTEM FOR BURST AREA OF MAGNETIC DISK DEVICE

PURPOSE:To prevent data from being mistakenly written in a servo signal area by inhibiting recording in a burst area only during a specific period that a rotating position detection means detects. CONSTITUTION:An index signal occurs the moment a hole 7 made in the rotar 1 of a spindle motor is detected. Meanwhile a detection signal far a hole element 6 occurs the moment polarity changes from S to N due to the passage of a rotor magnet. A period until initially a hole element signal occurs after the index signal has occurs is regarded as the burst area, that is, a recording inhibition period T1, and a recording inhibition signal is generated. Since the burst area and the recording inhibition signal are always synchronous although the rotation of the spindle motor fluctuates, servo information in the burst area is protected.