A novel type of magnetic recording head

Abstract

Conventional magnetic heads are not suitable when a large number of narrow tracks have to be recorded simultaneously. Attention has therefore been directed to types of head in which the magnetic field is produced by a relatively large current in short sections of a small diameter wire, without using any magnetic circuit. In this way it has been possible to record 40 tracks simultaneously on ¼ in tape. As a variant of this technique the wire is replaced by an evaporated strip of silver, placed transversely and edge-on to the tape. This provides a head which has intrinsically good ‘wear’ properties and also enables a pair of heads to record on interleaved tracks. A number of heads of this type have been made which provide 60 tracks on ¼ in tape.The design of these heads is discussed and it is shown that they are suitable for data recording and that they have a far smaller time constant than conventional heads. Their use for normal analogue recording is not yet feasible as the power dissipation is too high. However it is suggested that re-introducing a micro-magnetic circuit, by an evaporation technique, would overcome this problem while retaining the other advantages.