Recording disk with round spindle hole in magnetic hub and prerecorded tracking servo information

A disc cartridge comprising:

• a main cartridge body portion including a first half and a second half with an opening formed in one of said first half and said second half for inserting therein a spindle of a disc drive device;
• and
• a disc-shaped recording medium rotatably housed in said main cartridge body portion, wherein
• said disc-shaped recording medium includes a disc substrate having a major surface operating as a signal recording portion and a substantially circular center opening in said major surface and a hub composed of a magnetic material mounted on said disc substrate for closing said center opening provided in said disc substrate,
• said hub includes a circular center spindle opening for inserting therein said spindle and, said spindle opening is a predetermined tolerance with respect to said spindle, and at a predetermined distance from said spindle opening, a driving member inserting opening for inserting therein a driving member of said disc drive device, and said hub further includes an inner rim portion having said spindle opening formed at a center thereof, an outer rim portion, and a connecting portion interconnecting said inner portion and said outer rim portion, wherein said outer rim portion protrudes from said major surface by a distance that is greater than a distance by which said inner rim portion protrudes from said major surface,
• said signal recording portion is divided into a plurality of concentric recording tracks with each of said plurality of concentric recording tracks equiangularly divided into a plurality of servo frames, each of said plurality of servo frames divided into a servo area and a data area, and
• servo frame information is pre-recorded on said servo area for providing at least one of a gain control signal, a servo timing mark, a grey code area and a plurality of burst patterns located on either side of a center of said recording tracks and displaced from each other for providing a tracking servo.

A disc-shaped recording medium comprising:

• a disc substrate including a major surface operating as a signal recording portion and a substantially circular center opening in said major surface;
• and
• a hub mounted on said disc substrate for closing said center opening in said disc substrate, wherein
• said hub includes an inner rim portion having a spindle opening at a center of said inner rim portion and an outer rim portion connected to an outer side of said inner rim portion via a step difference for extending from said inner rim portion to a side from which a spindle is inserted into said spindle opening,
• said spindle opening is a predetermined tolerance with respect to said spindle.

A disc cartridge comprising:

• a main cartridge body portion including a first half and a second half with an opening formed in one of said first half and said second half for inserting therein a spindle of a disc drive device;
• and
• a disc-shaped recording medium rotatably housed in said main cartridge body portion, wherein
• said disc-shaped recording medium includes a disc substrate having a major surface operating as a signal recording portion and a substantially circular center opening in said major surface and a hub mounted on said disc substrate for closing said center opening in said disc substrate,
• said hub includes an inner rim portion having a center spindle opening for inserting therein said spindle and an outer rim portion connected to an outer side of said inner rim portion via a step difference for extending from said inner rim portion to a side from which said spindle is inserted into said spindle opening, and
• said center spindle opening is a predetermined tolerance with respect to said spindle.