GB638288A - Magnetic recording and reproducing - Google Patents

Abstract

638,288. Magnetic recording and reproducing apparatus. BRUSH DEVELOPMENT CO. Feb. 28, 1947, No. 5886. Convention date, March 2, 1946. [Class 40 (ii)] In a magnetic recording and reproducing apparatus using a disc or endless band record, the transducer is made to follow the magnetic track by means of a stylus which is coupled to the transducer and which engages a guide track whose movement is coupled to that of the magnetic track. When the record takes the form of a disc 31, Fig. 2, the guide member 4-21 may be supported on top of the disc 31 to which it is keyed by a pin 3-41, so that a stylus 61 which is coupled to the transducer 62 engages a spiral track 4-27 and causes the transducer 62 to traverse the magnetic surface 30 of the disc 31. In another form the spiral track may be formed on a raised centre part of the disc 31. In a further form the guide track may be mounted underneath the turntable 32 facing downwards, Fig. 18, the stylus 61 being carried by a separate arm 5-56 coupled to the transducer arm 60 by a spring 5-65. In yet another form the guide track may be carried on a lower turntable 5-11, Fig. 15, the stylus arm 5-21 being coupled to the transducer arm 60 by a link 5-32, wherein lost-motion is provided by means of a .pin-and-slot connection in order to ensure that both stylus 61 and transducer 62 make contact with their appropriate surfaces. Driving engagement between the shaft of the motor and the inner edge of the turntable is effected by means of jockey pulleys mounted on spring- loaded plates, Figs. 9 and 10 (not shown), the shaft of the motor being stepped to provide alternative speeds when coupled with one or the other of the jockey pulleys in order that either magnetic or ordinary gramophone records revolving at different speeds may be used, a suitable gramophone pick-up being provided for the latter type of record. In an alternative construction, Figs. 12 and 13 (not shown), a single jockey pulley is used and a second speed is obtained by the use of an intermediate shaft which is coupled to the motor shaft by a rubber tyre and is mounted on a separate spring-loaded plate which is moved under the control of a suitable changeover lever. When the magnetic record is a helical trace on a detachable endless band 6-11, Figs. 20 and 21, mounted on a drum, the transducer 6-12 is pivotally mounted on an arm 6-73 which is pivotally mounted on a sliding carriage 6-72, and which carries at its other end a stylus 61 engaging a guide track 6-13 on a cylinder 6-61 coupled to the drum by means of an intermediate wheel 6-63. The drum is driven by means of a motor shaft 3-12 and a rubber-tyred jockey wheel 6-91.