Eddy-current-assisted digital video read/write head

Abstract

The paper describes write fields and replay characteristics of gapped heads with magnetically recessed leading poles for high-frequency digital video. It describes an investigation by finite-element analysis and compares computed results for laminated Sendust and Co 91 Nb 6 Zr 3 heads and discusses the effects due to depositing a layer of copper inside the leading gap edge. Recessing the leading pole yields an asymmetric field, while eddy currents in the copper layer cause an advantageous redistribution of flux in the head. Predicted increases in both maximum horizontal field and horizontal field gradient by at least 130% and 17% are predicted for Sendust and Co 91 Nb 6 Zr 3 heads, respectively, at 100 MHz. Hence, such a head can write on higher coercivity media than a conventional gapped head. The playback performance is also improved by an extension of the frequency response. The paper gives a linear model for the phase of the spectral response, valid over a wide range of frequencies, for each of two leading pole recessions.Index Terms-Digital magnetic recording, eddy currents, finite element methods, magnetic recording/reading heads, video recording.