Patent ID: 8988816
Filing Date: 2015-03-24
Classification: G11B

Abstract:
1. A magnetic disk apparatus comprising: a plurality of magnetic disks; a plurality of heads configured to execute recording or reading with respect to the magnetic disks; a plurality of sensors provided in the heads, respectively, each of the sensors configured to output a signal in accordance with a flying height of the head from the magnetic disk; a writing module configured to simultaneously write servo data in the plurality of magnetic disks by using the plurality of heads; a control module configured to simultaneously execute a process of detecting a crash of the heads into the magnetic disks for the plurality of heads based on each output signal of the plurality of sensors when writing the servo data; a noise filter module configured to be shared with respect to each output signal of the plurality of sensors, wherein the control module executes a process for setting a flying height of the heads from the magnetic disks so as to be a predetermined value for the plurality of heads by letting each output signal of the sensors pass through the noise filter; and an OR gate into which each output signal of the plurality of sensors is input without passing through the noise filter, wherein the control module detects a crash in one of the plurality of heads based on an output signal of the OR gate.