Storage device, control device, and vibration-detection method

A control device used for a storage device for positioning at a predetermined position on a storage medium by driving an actuator with both a head and a vibration sensor, and at least for writing data onto the storage medium, the control device comprising:

• a filter for outputting a signal of a frequency band centered on a first frequency from an output of the vibration sensor;
• a write-protection-determination unit for protecting against data-writing processing upon a value of the output of the filter being larger than a threshold value;
• a position-error-signal-detection unit for detecting an amount of an off-track of the head;
• and
• a threshold-value-determination unit for determining the threshold value based on the off-track amount and a filter-output value when the actuator is driven at a second frequency.

A vibration-detection method used for a storage device configured to position a head at a predetermined position on a storage medium by driving an actuator with the head and at least to write data onto the storage medium, the method comprising the steps of:

• acquiring an output of a filter configured to pass a first frequency from an output of a vibration sensor mounted on the actuator;
• and
• protecting against data writing upon a value of the output of the filter being larger than a threshold value,
• wherein the first frequency is a frequency which is an integral multiple of a Nyquist frequency which is a half of a sampling frequency of servo information which is written onto the storage medium in advance.