Patent GB-510204-A (GB)
Title: Improvements in or relating to electro-mechanical devices for recording and reproducing sound oscillations on an endless film
IPC: G11B25/06
Filed: 1938-03-15
Abstract: 510,204. Tape-machines for recording and reproducing sound. RETERSON HOLDING SOC. ANON. March 15, 1938. No. 7961. Convention date, March 16, 1937. [Class 40 (ii)] Relates to machines for electro-mechanically recording and reproducing sound using as the record material a non-perforated endless film fed from a magazine in which it is spirally wound on rollers, and having a single feeddrum where the recording and reproduction are effected. According to the invention, the following features are provided in combination: (1) a recording member 34 and a reproducing member 33 co-operate either simultaneously or singly with the feed-drum 25, (2) one roller 28 of the magazine is positively rotated to release the inner convolution of the film, by gearing with the motor that drives the drum 25, and (3) a trip device 30 operated by the film controls the circuit of the motor, to stop the machine if required after a complete cycle of the endless film. In the machine shown diagrammatically in Fig. 2, the film is coiled at 27 in a removable casing, being wound around rollers 28, 42, the spindle of 28 being connected by a spring coupling to a pulley driven by a belt from a motor-driven flywheel 41, to the spindle of which the rubbercovered feed-drum 25 is connected. The roller 28 may be connected to the roller 42, and its speed is such that the film issues from the magazine without tension. Adjacent to the drum 25, arms 52, 51 carrying the recording'and reproducing devices 34, 33 respectively are pivotally mounted, substantially vertically, on a carriage on an horizontal spindle. Shavings 37 formed by the recorder 34 drop into a box 38, their removal from the record being facilitated by a blower 36. At a suitable point in the length of the film there is provided a notch or thickening which co-operates with the trip device 30 to stop the motor if required at the end of a single cycle of the film. The trip comprises a passage associated with which are spring contacts which close when the notch or thickening enters the passage. A push-button switch is provided, Fig. 6, (not shown), alternate closures of which operate, through a relay, to start and stop the motor at any time; a second manual switch is closed when it is desired to make the film-operated contacts effective to stop the film automatically. Fig. 5 shows the mechanism for feeding the recording and reproducing heads transversely across the film. The carriage 45 on which the arms 51, 52 are mounted, is threaded internally to engage a feed-screw V driven by the motor through a pulley 58, worm reduction gearing R, and a disconnectable coupling D. The coupling is engaged when it is desired to record or reproduce from a spiral track on the film; it is disengaged to prevent movement of the carriage when the sound tracks to be made or used run parallel to the edge of the film. Disengagement of the coupling is effected by longitudinally moving, by means of a button B, a spindle 61 which carries a disc member of the coupling. The spindle can be held in the declutching position by a catch (not shown), and with this setting the reproducing head can be moved into engagement with any selected record track by rotating the button B, whereby the feed-screw V is turned by means of pins 64 on the coupling-disc D. An indicator comprising a numbered dial 68, geared to the spindle 61 and movable past an observing lens 72, facilitates the setting of the recording and reproducing members, to pick out either a particular record track or a particular section of a spiral track. To bring the recorder and reproducer into action individually or simultaneously, cams 43 are provided on a shaft 71 to act upon extensions 70 of the arms 51, 52. These cams are moved, to raise and lower the recording and reproducing heads as required, by turning a crank 44 on the shaft 71. The crank carries a plunger 46, serving to close or open contacts in a switch 49 in such a manner as to control appropriately the circuits for recording and/or reproducing.