Patent ID: 6989957

Claim:
A disk storage device comprising: an information storing disk; a head for writing data to tracks on said disk and/or reading data from tracks on said disk; a head-moving mechanism that moves said head in response to an input signal; a head-position measuring circuit that generates a head-position signal representing a radial position of said head relative to said disk; a current feedback amplifier; a voltage feedback amplifier; and a controller that is configured to: generate a drive signal using a desired track-position signal and said head-position signal generated by said head-position measuring circuit, set an upper limit on said drive signal, monitor said head-position signal, or a signal derived from said head-position signal, to determine whether a malfunction condition exists, and in the event of determining that a malfunction condition exists, causing said drive signal to be applied as an input to said voltage feedback amplifier and causing an output from said voltage feedback amplifier to provide said input signal to said head-moving mechanism, or in the event of determining that a malfunction condition does not exist, causing said drive signal to be applied as an input to said current feedback amplifier and causing an output from said current feedback amplifier to provide said input signal to said head-moving mechanism.