Write-safe condition verification apparatus and method for the write element in a disc drive

This invention relates generally to the field of disc drive data storage devices and more particularly, but without limitation, to performing real-time, closed loop write verification by detecting electromagnetic coupling of constituent components making up the write path in the disc drive. A disc drive with on-the-fly verification of an enabled condition of the write element, comprising a rotatable disc having a magnetic recording surface, and a data reading and writing assembly. The data reading and writing assembly comprises a read/write head comprising a write element and a read element, both adjacent the recording surface; a preamplifier comprising a write driver applying a series of write currents for writing data to the recording surface and a read amplifier for reading stored data from the recording surface; and an interconnect joining the write driver to the write element so as to generate time-varying magnetic fields selectively magnetizing the recording surface in response to the write currents, and joining the read amplifier to the read element so as to transduce magnetization vectors on the recording surface associated with stored data. The disc drive furthermore comprises a detection circuit connected to the data reading and writing assembly, receiving a write-safe signal indicative of a write-safe condition, the write-safe signal comprising a sum of constituent operable magnetic coupling values of the read/write head, the preamplifier and the interconnect. The detection circuit is preferably connected to the preamplifier and receives the write-safe signal when a bias current is directed to the read element while writing data to the recording surface, such that a reversal in the writing current generates an electromagnetic coupling effect in the bias current. An advantageous construction comprises adaptively connecting the detection circuit to the analog buffer head voltage terminal of the preamplifier.