Erasing mechanism for recording medium producing visual display - uses two magnetic fields at right angles in plane of recording

摘要

A magnetic recording disc or tape used to provide a visual display, forming part of a registering system for the operation of e.g. a vehicle, has an erasing system with two magnetic fields in the plane of the recording medium, with the direction of the field at right angles to each other. The erasing mechanism consists of a single coil (4) with a minimum of two limbs (2, 3) in the same plane, each preferably with a rectangular cross section (5). The two limbs intersect at a point outside the width of the recording track (6). The coil (4) can be supplied either with direct or with alternating current. When alternating current is used for the excitation, the alternating fields are made effective by improved eddy current dissipation.