Disk used for calibrating floating height of protrusion detection head, method of calibrating floating height of protrusion detection head using the disk and glide tester using the method

A method of calibrating the floating height of a protrusion detection head for a magnetic disk which makes use of a bump disk, comprising:

• using a standard protrusion having a predetermined height and a plurality of reference protrusions positioned either on substantially the same radial line as the standard protrusion or on a circumferential line having substantially the same radial distance as the standard protrusion under a predetermined positional relationship with respect to the standard protrusion, the bump disk being mounted on a spindle on which either the bump disk or a magnetic disk is selectively mounted, further including:
• a standard protrusion identification step in which the protrusion detection head is loaded over the bump disk mounted on the spindle, through the rotation of the spindle the protrusion detection head is lifted, the protrusions on the bump disk are inspected via the protrusion detection head to detect positions of the standard protrusion and the reference protrusions, and the standard protrusion on the bump disk is identified based on the condition that the reference protrusions are positioned either on substantially the same radial line as the standard protrusion or on a circumferential line having substantially the same radial distance as the standard protrusion and based on the predetermined positional relationship;
• and
• a circumferential speed determining step which obtains either a circumferential speed at which in accordance with the variation of the rotating speed of the spindle bumping of the protrusion detection head with the standard protrusion identified in said standard protrusion identification step occurs starting from a condition in which no bumping of the protrusion detection head with the identified standard protrusion occurs or another circumferential speed at which in accordance with the variation of the rotating speed of the spindle bumping occurrence is ceased starting from a condition in which bumping is occurring, wherein the magnetic disk is rotated either at one of the circumferential speeds determined in the circumferential speed determining step or at a circumferential speed calculated based on the determined circumferential speeds to lift the protrusion detection head.

A glide tester, comprising:

• a protrusion detection head for a magnetic disk;
• a bump disk including a standard protrusion having a predetermined height and a plurality of reference protrusions positioned either on substantially the same radial line as the standard protrusion or on a circumferential line having substantially the same radial distance as the standard protrusion under a predetermined positional relationship with respect to the standard protrusion;
• a spindle on which either said bump disk or the magnetic disk is selectively mounted;
• a standard protrusion identification means in which said protrusion detection head is loaded over said bump disk mounted on said spindle, through the rotation of said spindle said protrusion detection head is lifted, the protrusions on said bump disk are inspected via said protrusion detection head to detect the positions of the standard protrusion and the reference protrusions, and the standard protrusion of said bump disk is identified based on the condition that the reference protrusions are positioned either on substantially the same radial line as the standard protrusion or on the circumferential line having substantially the same radial distance as the standard protrusion and based on the predetermined positional relationship;
• a circumferential speed determining means which obtains either a circumferential speed at which in accordance with the variation of the rotating speed of said spindle, bumping of said protrusion detection head with the standard protrusion identified in said standard protrusion identification means occurs starting from a condition in which no bumping of said protrusion detection head with the identified standard protrusion occurs or another circumferential speed at which, in accordance with the variation of the rotating speed of said spindle, bumping occurrence is ceased starting from a condition in which bumping is occurring;
• and a protrusion inspection means which performs a protrusion inspection by rotating the magnetic disk either at one of the circumferential speeds determined in said circumferential speed determining means or at a circumferential speed calculated based on the determined circumferential speeds and by lifting the protrusion detection head.