Abstract: Embodiments of the present invention allow for a precise altitude to be calculated from read-out signals of a head slider. In one embodiment, a hard disk controller/multiprocessing unit (HDC/MPU) determines a head element portion in which the instability has occurred in accordance with the resolution change. The HDC/MPU adjusts the clearance accordingly. The head element portion reads signals of different frequencies under a condition of the signal strengths coinciding with a reference value, and the HDC/MPU calculates the resolution. The HDC/MPU determines that the instability has occurred if the difference is outside the criterion. The HDC/MPU uses the read-out signal of a head slider in which the instability has not occurred to calculate the altitude.

Abstract: Embodiments of the present invention efficiently conduct a test for detecting defects on a magnetic disk more accurately. According to one embodiment, a HDD carries out defect inspection of a magnetic disk using thermal fly height control (TFC). Changing a clearance by the TFC achieves defect inspection tests under varied test conditions without much decrease of throughput in manufacturing HDDs. First, a self analysis test (SAT) is carried out in a state that a heater power of P2 is supplied to a heater. Then, another SAT is carried out in a state that a heater power of P1 is supplied to the heater. The heater power P2 is larger than the heater power P1.

Abstract: Embodiments of the present invention allow for a precise altitude to be calculated from read-out signals of a head slider. In one embodiment, a hard disk controller/multiprocessing unit (HDC/MPU) determines a head element portion in which the instability has occurred in accordance with the resolution change. The HDC/MPU adjusts the clearance accordingly. The head element portion reads signals of different frequencies under a condition of the signal strengths coinciding with a reference value, and the HDC/MPU calculates the resolution. The HDC/MPU determines that the instability has occurred if the difference is outside the criterion. The HDC/MPU uses the read-out signal of a head slider in which the instability has not occurred to calculate the altitude.

Abstract: Embodiments of the present invention efficiently conduct a test for detecting defects on a magnetic disk more accurately. According to one embodiment, a HDD carries out defect inspection of a magnetic disk using thermal fly height control (TFC). Changing a clearance by the TFC achieves defect inspection tests under varied test conditions without much decrease of throughput in manufacturing HDDs. First, a self analysis test (SAT) is carried out in a state that a heater power of P2 is supplied to a heater. Then, another SAT is carried out in a state that a heater power of P1 is supplied to the heater. The heater power P2 is larger than the heater power P1.