Patent ID: 7770438

Claim:
A glide height checking apparatus, comprising: a head slider with an air bearing surface, utilized for checking a magnetic disk, and a current control section; wherein the head slider including a plurality of heaters, each heater locally heating a corresponding region of the air bearing surface, and a sensor detecting collision of the air bearing surface with a projection on a surface of the magnetic disk; and a storage section storing asperity information; wherein the current control section supplies a current to each of the plurality of heaters, magnitude of the current being determined based on the asperity information which represents asperity condition of the air bearing surface, the asperity information corresponds to magnitude of a current which is supplied to each of the plurality of heaters such that the sensor output is constant irrespective of location of collisions of the air bearing surface with the projection on a surface of the magnetic disk, the collisions being produced in a condition that the head slider is allowed to fly on the magnetic disk rotating with a constant linear velocity and to move in a radial direction of the magnetic disk, so that the projection on the surface of the magnetic disk is allowed to collide, one after another in order, with the air bearing surface at some points thereon.