Patent GB-739381-A (GB)
Title: Improvements in or relating to devices for winding tape
IPC: G11B15/32
Filed: 1952-08-22
Abstract: 739,381. Driving sound film or tape. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Aug. 22, 1952 [Aug. 25, 1951], No. 21169/52. Class 40 (2). [Also in Group XVI] In a device for winding tape from one spool to another, such as in a magnetic recording and reproducing apparatus, the spools are coupled by a transmission mechanism comprising friction wheels which are in contact with the spools and whose position in relation to the spools varies in accordance with the diameters of the tape on the spools, means being provided in the transmission mechanism such that the tape is tensioned. In one embodiment described with reference to Fig. 1, transmission shafts 13, 14, Fig. 2, coupled by friction element 30 and reversing gear 16, carry keyed friction wheels 9, 10 respectively, which are pressed against the flanges 11, 12 of spools 5, 6 and are moved radially of the spools in accordance with the position of feeler wheels 17, 18 pressed against the outer convolutions of the tape. The tape during forward winding is drawn from spool 5 by a capstan 3 and tension in the tape is produced by adjusting the position of the friction wheel 10 so that it is in contact with the spool 6 at a radial position somewhat inward of the radius of the outer convolution of the tape, thus tending to turn the spool 6 at a faster speed than required. During rewinding the wheel 9 is moved to a position inward of the outer convolution on spool 5. In another embodiment, also described with reference to Figs. 1 and 2, there is no capstan 3, and the tape is wound directly on to spool 6 by the wheel 10. In this embodiment, however, the wheel 9 is adjusted, during forward winding on to spool 6, to be at a radial position outward of the outer convolution of the tape on spool 5, so that the shaft 13 is turned too fast and a frictional drag is produced by the element 30. During rewinding on to spool 5, the wheel 9 is moved to a radial position inside the outer turn on the spool 5, so that a tendency is produced to turn the spool 5 too fast, and again tension the tape. In a modification of this embodiment, the friction element 30 is omitted and replaced by driving elements 32, 33 which have positive drives in the direction for winding on with their respective spools, but have friction slip in the opposite direction. In this case the wheel 9 or 10 associated with the emptying spool is moved to a radial position outward of the outermost convolution on the spool. Fig. 4 shows a means whereby the friction wheel 9 or 10 may be automatically displaced in an axial direction according to its direction of rotation, the wheel 9 or 10 being mounted on a threaded bush 35. In an embodiment described with reference to Fig. 6, the feeler wheels 17, 18 are dispensed with and the wheels 9, 10 are coupled by a differential gear. As one of the spools 5, 6 fills, its appropriate wheel 9, 10 rotates at a lower speed than the other and produces a rotation of the cage 44 which has an encircling gear wheel 45 which in turn rotates a gear element 46 keyed to a shaft 47 carrying lead screws 48, 49, whereby the radial positions of the wheel 9, 10 are automatically adjusted. A spiral spring 54 in conjunction with a circular friction element 55 restricts the rotation of cage 44 and thereby delays the adjustment of wheels 9, 10, so that the one appropriate to the take-up spool 5 or 6 is always in a radial position nearer the centre of the outer convolution of the tape, thereby maintaining tension in the tape. As the cage 44 always rotates in the same direction irrespective of the direction of travel of the tape, the gear element 46 includes a reversing element which is brought into operation when moved to the left into the dotted position shown in Fig. 6, while the tape is driven from the spool 6 to the spool 5.