Disk device and disk drive controlling method

A disk drive controlling method comprising the steps of:

• performing main control processing that controls the operation of a controlled object on the basis of an error signal calculated from a target signal of the controlled object which will become necessary incidentally to recording of data in a disk medium and/or reproduction of data recorded in the disk medium and an observation signal of the controlled object;
• performing repetitive control processing that samples the error signal with a sampling clock pulse to obtain a repetitive signal component which is generated in synchronization with rotation of the disk medium from the sampled error signal;
• performing sampling clock generation processing that generates the sampling clock pulse used to sample the error signal and resets a timing at which the sampling clock signal is generated with a rotation detecting pulse generated when rotation of the disk medium has been detected;
• and
• performing sampling clock limit processing that limits generation of the sampling clock signal at a timing immediately before generation of the rotation detecting pulse.