A flying height tester that can vary an air pressure and measure an air bearing height between a slider and a substrate. The substrate is located within a chamber that has an air pressure. The tester includes a loader which places a slider adjacent to the substrate. An optical system computes the air bearing height from a light beam that is directed through the substrate and reflected off of the slider. The chamber is coupled to a pressure control system that can vary the pressure of the air surrounding the slider. The pressure control system varies the pressure to simulate slider operation at various altitudes. The tester of the present invention can thus measure air bearing height while simulating various altitude conditions.
A computer hard disk drive has a drive controller that monitors the condition of the head-disk interface within the drive. The drive normally operates under ambient or relatively low internal pressure. However, when the drive is in imminent risk for a head-disk interface failure, the drive is pressurized to allow the air bearing surfaces of the heads to achieve a greater flying height above the surfaces of their respective disks, thereby delaying the onset of a catastrophic head-disk interface failure. In addition, the spindle rotation rate and/or the slider head access rate are decreased to avoid hastening the imminent failure. Measurements of the condition and stability of the head-disk interface inside the drives are made by monitoring data error rates, head flying height, and other performance variables.
A disk drive controller controls a vacuum pump to establish a vacuum within a disk drive housing to conserve power while ensuring that the head of the drive does not crash into the disk. The controller compares actual spindle power to a predetermined maximum power threshold and actual fly height to a calibration fly height to control the pump. The calibration values are derived by comparing no-load and loaded values for a parameter, e.g., error rate, disk temperature, and so on.
