Tohru Kira

Identification of the place causing Barkhausen noise in yoke type MR heads

In yoke-type magnetoresistive (MR) heads, Barkhausen noise occurs in different regions depending on various applied fields. The place causing the noise can be specified by comparing the observed change of noise with the calculated field distribution in the head when an internal bias is superimposed on a uniform external field. Using a recording coil current instead of a uniform external field, noise from a bottom yoke or a substrate is clearly detected. >

Combined Type Thin Film Head For Dcc

An inductive head for recording and a yoke type MR head for playback have been employed in a DCC system. It is difficult to fabricate these heads on the same substrate while controlling the head properties. We therefore developed a new hybrid thin film head. The new combined structure of the head enables simplification of the production process, and the head proved to be suitable for use in DCC systems.

Combined thin-film heads for digital compact cassettes

A combined thin-film head has been developed for digital-compact-cassette (DCC) recording. In this head, the inductive recording head is placed behind the yoke-type magnetoresistive (MR) playback head. This design greatly simplifies fabrication by reducing the number of layers. Therefore, its structural stability and productivity are superior to those of other head designs. Its recording current is similar to that of a conventional thin-film recording head. The maximum output-level current is 120-160 mA/sub 0-p/, and the average output at 48 kHz exceeds 100 mu V/sub p-p/. The overwrite characteristics of 48 kHz on 9.6 kHz are about -19 dB. The influence of the recording field on the playback characteristics of the yoke-type MR head is negligible. This head has the characteristics required for DCC recording and playback. >

Thin film heads for digital multi-channel recorder

The fabrication and performance of thin film magnetic heads newly developed for a digital multi-channel recorder are described. The reproducing head is a yoke type magnetoresistive head and the recording head is an inductive head. Four kinds of noise peculiar to the yoke type magnetoresistive heads have been completely suppressed by strict control of process conditions. Two new processes for a coil and a core have been applied to the recording head. Two reproducing heads and one recording head are assembled in a tape guide block ensuring accurate tape transport and stable tape-to-head contact. The characteristics of both the reproducing head and the recording head have proved to be sufficient for a digital multichannel recorder. >