GB497800A - System of electromagnetic sound recording on metallic plates, ribbons or wires - Google Patents

Abstract

497,800. Telegraphones. MARZOCCHI, L. June 28, 1937, Nos. 17999 and 18000. Convention dates, June 26, 1936 and April 17, 1937. [Class 40 (ii)] In an electromagnetic recording system of the Poulsen type, the magnetizable wire or strip is given a uniform longitudinal movement whilst the electromagnets rotate round the axis of the wire or in a plane parallel or perpendicular to the plane of the moving strip. Fig. 1 shows the application to a wire 1 fed by rollers 3 from drum 2 to drum 5 through a hollow shaft 12 carrying the electromagnet 6 and rotated by driving means 16 in fixed bearings 13. The shaft is threaded to drive a worm wheel 17 geared to the rollers 3. A helical record trace is therefore impressed on the wire. The trace may be of single or multiple helical form. Fig. 4 shows the application to a strip, the electromagnets 21, 22, 23 being carried by a disc 26 rotated parallel to the plane of the moving strip 18 to produce traces of the form shown in Fig. 2. Means such as contact rings 25 permit of cutting out the magnets during the non-recording parts of their revolution. The other side of the strip may be recorded upon by using a second rotary disc 26<1>. Fig. 11 shows a strip record giving a uniform tone intensity as the magnets pass on to and off the strip. The central band A is of full tone intensity, the bands B, B<1> of gradually increasing and decreasing intensity and the bands C are unrecorded.