Patent ID: 7787214

Claim:
A disk apparatus, comprising: a hub having a disk inserting portion having a cylindrical plane in the outer part of one end and a disk receiving portion having a flat part and being pivotably supported; a disk-shaped recording medium having an inner hole through which the disk inserting portion is fitted and being held by the disk receiving portion; a head facing toward at least one face of the disk-shaped recording medium, levitating and scanning above the disk-shaped recording medium and reading a signal recorded on the disk-shaped recording medium or writing a signal on the disk-shaped recording medium; and clamp means holding the disk-shaped recording medium with the disk receiving portion, the clamp means having a clamp member mounted on a top face of the hub, wherein the hub is formed with a contact point or contact plane between the hub and the disk-shaped recording medium at a distance Rh from a rotational axis center and the clamp member is formed with a contact point or contact plane between the clamp member and the disk-shaped recording medium at a distance Rs from the rotational axis center, and wherein a difference between the distances Rh and Rs is selected so that the disk-shaped recording medium includes a warp greater than 0 μm and less than or equal to 15 μm, an amount of the warp being controlled independent of a predetermined operating temperature, and wherein a relationship between the distances Rh and Rs is Rs<Rh when the head is provided on the disk receiving portion side of the hub with respect to the disk-shaped recording medium and is Rs>Rh when the head is provided on the clamp member side.