GB865188A - Improvements in or relating to cassettes for magnetic recorders and recorders for use with these - Google Patents

Abstract

865,188. Magnetic recording and reproducing apparatus. EPSYLON RESEARCH & DEVELOPMENT CO. Ltd. July 10, 1957 [March 21, 1957], No. 16138/57. Class 40 (2). In a magnetic recorder wherein the record medium 3 passes between a pair of externallydriven spools 2 in a cassette 1 to traverse a magnetic transducer, the transducer consists of a magnetizable head 4 . . . 6 embodied in the cassette and having ends adapted to be engaged with an external magnetic circuit 7. For use with a record medium 3 of a synthetic resin thread coated or impregnated with magnetizable material, the head may consist of lowfriction guides 4 (e.g. of polyfluorethylene or of a porous material impregnated therewith) each having a tapered bore serving to centre the record thread in a circular aperture in highly permeable pole-pieces 5 separated by a beryllium-copper spacer 6, the parts 4 . . . 6 being sealed into the cassette to retain a silicone lubricant filling. The magnetic circuit may consist of an electromagnet 7 with arms of sufficient resilience to press against the sides of the pole-pieces 5 when inserted in apertures la. In a modification for reproducing low frequencies (Fig. 3, not shown), the record passes through two small tubes of moderate permeability and high resistivity inserted in the pole-pieces 5 and extending into the guides 4; the pole-pieces are turned outwards at their outer ends to present butting faces to an electromagnet 7 held in place by bifurcated spring spigots. The drive to the spools 2 may include a slipping clutch to prevent the record 3 (permanently secured to the spools at its ends) from breaking; the force at maximum slip may be used to switch-off the winding means. A thread traverser may be associated with the take-up spool. The spools 2 may be arranged on a common axis.