Method and apparatus to write and inspect servo information on a disc drive

A method to write servo information on a disc in a disc drive, the method comprising:

• sequentially writing servo information from a track of the disc having a least number to a track having skew ‘0’;
• after writing the servo information to the track having skew ‘0’, moving a head to a track having the largest number;
• sequentially writing the servo information from the track having a largest number to a track prior to the track having skew ‘0’;
• and
• after writing all the servo information, inspecting the servo information written in a track at a predetermined distance from the track having skew ‘0’, and determining whether the servo information is correctly written.

A method to write and inspect servo information on a disc in a disc drive, the method comprising:

• writing servo information on a track of the disc;
• inspecting the servo information written in the track;
• if an error occurs in the track, determining whether the number of the track in which the error occurs corresponds to a track at a predetermined distance from a track having skew ‘0’;
• if the number of the track in which the error occurs corresponds to the track at the predetermined distance from the track having skew ‘0’, writing the servo information again, and if not, track-defect-processing the track in which the error occurs;
• and
• if all tracks have been inspected, track-defect-processing tracks within the predetermined distance from the track having skew ‘0.

A disc drive comprising:

• a disc having a surface;
• a spindle motor that rotates the disc;
• a transducer that writes and reads information in and from the disc;
• a voice coil motor that moves the transducer;
• and
• a controller that controls the transducer to
• sequentially write servo information toward a track of the disc having skew ‘0’ from an outer portion of the surface in an outer region of the disc,
• sequentially write servo information toward the track having skew ‘0’ from an inner portion of the surface in an inner region of the disc, and
• after the writing of the servo information is completed, to inspect the servo information written in a track at a predetermined distance from the track having skew ‘0’ and determining whether the servo information is correctly written.

A method to write servo information on a disc drive including a disc and a writing head, the method comprising:

• positioning the writing head at one of an inner portion and an outer portion of the disc;
• writing servo information on sequential tracks until writing servo information on a skew zero track, in which a skew between a tangent to the skew zero track and an axis of the writing head is approximately zero;
• positioning the writing head at the remaining of the inner portion and the outer portion of the disc;
• writing servo information on sequential tracks until writing servo information on a track immediately preceding the skew zero track;
• and
• inspecting the servo information on a track located a predetermined distance from the skew zero track to determine if a predetermined tolerance of the writing of the servo information was exceeded.

A method to write servo information on a disc drive including a writing head and a disc with tracks, the method comprising:

• defining a skew zero track as the track in which a skew between a tangent to the skew zero track and an axis of the writing head is approximately zero;
• positioning the writing head at a track at one of an inner portion and an outer portion of the disc and writing servo information;
• positioning the writing head on a next sequential track toward the skew zero track and writing servo information, until writing servo information on the skew zero track;
• positioning the writing head at the remaining of the inner portion and the outer portion of the disc and writing servo information;
• positioning the writing head on a next sequential track toward the skew zero track and writing servo information, until writing servo information on a track immediately preceding the skew zero track;
• and
• inspecting the servo information on a track located a predetermined distance from the skew zero track to determine if a predetermined tolerance of the writing of the servo information was exceeded.

A method to write servo information on a disc drive including a writing head and a disc with tracks, the method comprising:

• defining a skew zero track as the track in which a skew between a tangent to the skew zero track and an axis of the writing head is approximately zero;
• writing servo information on sequential tracks in a first radial direction of the disc toward the skew zero track, until servo information is written on the skew zero track;
• writing servo information on sequential tracks in a second radial direction of the disc, opposite the first direction, toward the skew zero track, until servo information is written on a track immediately preceding the skew zero track;
• and
• inspecting the servo information to determine if a predetermined tolerance of the writing of the servo information was exceeded.

A disc drive, comprising:

• a reading and writing head;
• a disc;
• and
• a controller, controlling the reading and writing head to
• write servo information on sequential tracks in a first radial direction of the disc toward a skew zero track until servo information is written on the skew zero track;
• write servo information on sequential tracks in a second radial direction of the disc, opposite the first direction, toward the skew zero track, until servo information is written on a track immediately preceding the skew zero track, and
• inspect the servo information to determine if the predetermined tolerance of the writing of the servo information was exceeded,
• wherein the skew zero track is defined as the track in which a skew between a tangent to the skew zero track and an axis of the reading and writing head is approximately zero.

A computer readable medium, comprising;

• a first set of instructions to define a skew zero track as a track of a disc in which a skew between a tangent to the skew zero track and an axis of a writing head is approximately zero;
• a second set of instructions to write servo information on sequential tracks in a first radial direction of the disc toward the skew zero track until servo information is written on the skew zero track;
• a third set of instructions to write servo information on sequential tracks in a second radial direction of the disc, opposite the first direction, toward the skew zero track, until servo information is written on a track immediately preceding the skew zero track
• a fourth set of instructions to inspect the servo information to determine if the predetermined tolerance of the writing of the servo information was exceeded.

A method, comprising:

• determining whether an area of a hard disc contains tracks in which servo information is superimposed;
• and
• if such an area is discovered, inspecting the tracks in the area for abnormalities in the servo information;
• and track-defect-processing the tracks.

A method, comprising:

• determining whether an abnormality occurs in servo information written in a track of a disc, at a predetermined distance from a skew zero track;
• if the abnormality is discovered, rewriting the servo information on the disc;
• and
• if the abnormality is not discovered, track-defect-processing tracks within the predetermined distance from the skew zero track.