Multi-impact thermal asperity sensor head

摘要

An asperity height sensing head and method of using the same are disclosed. The head includes multiple magnetoresistive (MR) sensors carried by a first rail of a slider adjacent to the air bearing surface (ABS) and positioned a distance Lp from each other. Asperity height estimating circuitry coupled to each of the multiple MR sensors detects a number N of the MR sensors which exhibit a change in resistance as a result of contact between the ABS and a first asperity on the surface of the disc. The asperity height estimating circuitry estimates the height HA of the first asperity as a function of the number N, as a function of the pitch angle theta p , and as a function of the distance Lp.