US 7,405,897 B2Granted

Single-pass self-servowriting method and system employing a low sector rate startup procedure

AssigneeHitachi Global Storage Technologies Netherlands B.V.

InventorsKenneth James Dougherty, Gary Allan Herbst, Jong Ming Lin

Life of this patent

Estimating the term…

Loading patent…

Abstract

A self-servowriting (SSW) method that, with the actuator fully engaged against a compliant structure (e.g., a crashstop), first writes a tightly-spaced open-loop sequence of servo bursts in a segmented spiral path and then continues writing this tightly-spaced sequence under closed-loop servo control while reading back amplitude information from the servo bursts written earlier until the tightly-spaced burst pattern extends over several read-write head (RWH) offset intervals. With the actuator still engaged against the compliant structure, this tightly-spaced startup sequence is then read back by the closed servo control loop to write a number of concentric servo seed tracks, which are then self-propagated across the remainder of the disk surface to produce a final servopattern.

Claims20

Dependent claims

A method for writing embedded servo position information in the data storage tracks of a data storage device (DSD) having (1) a rotating data storage medium with at least one data storage surface containing the data storage tracks each disposed over a plurality of sectors, (2) a read/write head (RWH) disposed in a transducing relationship with the data storage surface, (3) an actuator for disposing the RWH in a radial position on the data storage surface according to a voice-coil motor (VCM) signal value, (4) at least one crashstop disposed to limit actuator motion, and (5) a servo control loop for producing the VCM signal responsive to information read from the data storage surface, the method comprising the steps of:

(a) forcing the actuator against a crashstop, thereby moving the RWH to a crashstop region of the data storage surface;
(b) writing an open-loop sequence of servo bursts in the crashstop region;
(c) writing a closed-loop sequence of servo bursts each positioned in the crashstop region according to amplitude information read from a plurality of servo bursts written earlier;
(d) writing a plurality of closed-loop servo seed tracks each positioned in the crashstop region according to amplitude information read from a plurality of servo bursts written earlier;
and
(e) writing a plurality of servo tracks each positioned according to servo positioning information read from a servo track written earlier, whereby the servo tracks are propagated across the data storage surface from the servo seed tracks under servo loop control.

3 more elements

A data storage device (DSD) comprising:

a rotating data storage medium having at least one data storage surface defining a plurality of generally concentric data storage tracks each disposed over a plurality of sectors;
a read/write head (RWH) supported in a transducing relationship with the data storage surface by an actuator;
at least one crashstop disposed to limit actuator motion;
a voice coil motor (VCM) coupled to the actuator for positioning the RWH responsive to a VCM signal;
a servo control loop coupled to the VCM and the RWH for producing a VCM signal responsive to information read from the data storage tracks;
and
a servowriting controller coupled to the servo control loop for writing the embedded servo position information in the data storage tracks on the data storage surface, comprising:
means for forcing the actuator against a crashstop, thereby moving the RWH to a crashstop region of the data storage surface,
means for writing an open-loop sequence of servo bursts in the crashstop region,
means for writing a closed-loop sequence of servo bursts each positioned in the crashstop region according to amplitude information read from a plurality of servo bursts written earlier,
means for writing a plurality of closed-loop servo seed tracks each positioned in the crashstop region according to amplitude information read from a plurality of servo bursts written earlier, and
means for writing a plurality of servo tracks each positioned according to servo positioning information read from a servo track written earlier, whereby the servo tracks are propagated across the data storage surface from the servo seed tracks under servo loop control.

9 more elements

Dependencies are inferred from the claim text.