Method for seeking in a magnetic disk drive having a spiral track

In a disk drive having a transducer head, a magnetic disk with a spiral track, and an actuator for moving the head across and positioning the head over a surface of the magnetic disk in response to control currents, the magnetic disk rotating at a constant angular velocity and the spiral track having contiguous storage segments, each storage segment including a servo sector and a predetermined number of data sectors, the storage segments being situated along the spiral track such that the servo sectors may not be aligned along a radius of the magnetic disk, a method for seeking from a current storage segment at a first radial position to a desired storage segment at a second radial position, comprising:

• determining a head transit time for moving the head from the first radial position to the second radial position according to a desired velocity profile;
• applying a first control current pulse to the actuator, wherein the first control current pulse has an amplitude and a duration designed to cause the head to move from the first radial position toward the second radial position at a coast velocity resulting solely from the application of the first current pulse and not resulting from a velocity measurement during the head movement from the first radial position to the second radial position;
• after applying the first control current pulse to the actuator, commencing a timer for measuring the expiration of the head transit time after applying the first control current pulse;
• reading a servo sector encountered during the head movement to determine the actual position of the head at the encountered servo sector;
• adjusting the head transit time based on the actual position of the head at the encountered servo sector;
• after expiration of the adjusted head transit time, applying a second control current pulse to the actuator to terminate the head movement;
• and
• after applying the second control current pulse, reading at least one servo sector along the spiral track to locate the position of the head with respect to the desired storage segment.

A disk drive, comprising:

• a transducer head;
• a magnetic disk with a spiral track, the magnetic disk rotating at a constant angular velocity and the spiral track having contiguous storage segments, each storage segment including a servo sector and a predetermined number of data sectors, the storage segments being situated along the spiral track such that the servo sectors may not be aligned along a radius of the magnetic disk;
• an actuator for moving the head across and positioning the head over a surface of the magnetic disk in response to control currents;
• means for seeking from a current storage segment at a first radial position to a desired storage segment at a second radial position, the seeking means including
• means for determining a head transit time for moving the head from the first radial position to the second radial position according to a desired velocity profile;
• means for applying a first control current pulse to the actuator, wherein the first control current pulse has an amplitude and a duration designed to cause the head to move from the first radial position toward the second radial position at a coast velocity resulting solely from the application of the first current pulse and not resulting from a velocity measurement during the head movement from the first radial position to the second radial position;
• timer means for measuring the expiration of the head transit time after applying the first control current pulse;
• means for applying a second control current pulse to the actuator to terminate the head movement after expiration of the head transit time;
• and
• means for reading at least one servo sector along the spiral track after applying the second control current pulse to locate the position of the head with respect to the desired storage segment.

A disk drive, comprising:

• a transducer head;
• a magnetic disk with a spiral track, the magnetic disk rotating at a constant angular velocity and the spiral track having contiguous storage segments, each storage segment including a servo sector and a predetermined number of data sectors, the storage segments being situated along the spiral track such that the servo sectors may not be aligned along a radius of the magnetic disk;
• an actuator for moving the head across and positioning the head over a surface of the magnetic disk in response to control currents;
• means for seeking from a current storage segment at a first radial position to a desired storage segment at a second radial position, the seeking means including
• means for determining a head transit time for moving the head from the first radial position to the second radial position according to a desired velocity profile;
• means for applying a first control current pulse to the actuator, wherein the first control current pulse has an amplitude and a duration designed to cause the head to move from the first radial position toward the second radial position at a coast velocity resulting solely from the application of the first current pulse and not resulting from a velocity measurement during the head movement from the first radial position to the second radial position;
• timer means for measuring the expiration of the head transit time after applying the first control current pulse;
• means for reading a servo sector encountered during the head movement to determine the actual position of the head at the encountered servo sector;
• means for adjusting the head transit time based on the actual position of the head at the encountered servo sector;
• means for to the actuator to terminate the head movement after expiration of the adjusted head transit time;
• and
• means for reading at least one servo sector along the spiral track after applying a second control current pulse to locate the position of the head with respect to the desired storage segment.