Abstract: A method for determining the surface distortions of a disk in a spin-stand or single or multiple disk hard disk drive (HDD) utilizing a DFH type write head. A stepwise power curve is supplied to the DFH head, the head is flown over a chosen track on the disk, and the high frequency signal from a HDI sensor is analyzed in order to determine the step of an initial touchdown power and the step of a complete touchdown power as a function of individual sectors in a sector subdivision along a chosen track. The HDI sensor signal is averaged within each step of the power curve between these two steps and a Ratio variable, Ratio=(Max. amplitude)/(RMS amplitude) is calculated for each step and is averaged over each rotation of the disk during the step.

Abstract: An information recording device in accordance with the present invention obtains drive information of a semiconductor laser which is included in a magnetic head by means of a drive information obtaining section and successively records the information in a drive information storing section. A magnetic head control section controls the magnetic head in accordance with a condition of the semiconductor laser on the basis of the drive information thus obtained by the drive information obtaining section.

Abstract: Apparatuses and methods for certifying a magnetic recording disk (102) are disclosed herein, in a described embodiment, the apparatus (100) comprises a certifier head (104) for testing the disk's magnetic properties and a product head (106) for testing the disk's mechanical properties and the apparatus (100) is configured to enable simultaneous access to the disk (102) by the product head (106) and the certifier head (104). A method of upgrading a media certifier is also disclosed.

Abstract: Address information that has been error correction encoded is recorded on a second version of a recording medium after being transformed such that such that the address decoding cannot be performed by a playback device that is not compatible with the second version of the recording medium. The address decoding for the second version of the recording medium cannot be performed by the incompatible playback device (for example, a playback device that was manufactured to be compatible only with a first version of the recording medium). In other words, in the playback device that is not compatible with the second version of the recording medium, a state is created in which address errors cannot be corrected, so access is impossible (recording and playback are impossible).