Patent GB-692661-A (GB)
Title: Improvements in or relating to magnetic recording and reproducing apparatus
Inventor: CAMRAS MARVIN
IPC: G11B5/004
Filed: 1951-03-19
Abstract: 692,661. Magnetic sound recording and reproducing apparatus. INTERNATIONAL RESEARCH & DEVELOPMENT CORPORATION. March 19; 1951. No. 6502/51. Class 40 (ii): Before starting the winding of a a magnetizable sheet record around a drum 15, Fig. 3, having a rubber or cork facing, the magnetic head 19 is moved to the position shown in dot-dash lines; by rotating a pinion 87 which engages a rack 69 on which the head is pivotally mounted. A transverse pin 72 on the rack engages fixed guideplates 71 to cause the head to tilt upwards as it is moved back. The feed nut, for moving the head across the drum, which may comprise the downturned sides 79 of a leaf spring may also be disengaged from the head screw 56 by rotating an operating bar 85 to rotate a cam 84 which lifts an arm 81 thus raising a rod 80 fixed to the leaf, spring. The record sheet is placed between angles 120 of a guide 119 and is held in position by a transverse bar (Fig. 1, not shown). A motor 11 is started and a button 48 pressed to engage a clutch 37 and rotate the drum. A gear 54 is also rotated, and a cam. on the gear causes a rocking member 145 to pivot inwardly, see Figs. 5 and 6 (not shown). This movement causes an arm 141 to move down and with the aid of a spring 136 push a pivoted shoe 129, having a lining 132, Fig. 8, of plush, felt or velvet against the leading edge of the record. The lining has edges wich extend at opposite helical angles from a central point, to spread the sheet record along the drum. As the drum rotates The record is fed downwardly and around the drum and. within a casing 111, under tension exerted by the transverse bar of the guide 119. Strips of plush 133, 134 are provided on the lining 132 and the casing 111 to help to spread the record. The shoe 129 is released from engagement with the record by movement of a plunger 150 which cause the member 145 to be rocked into an upright position. Several sheet records may be wrapped around the drum to make duplicate recordings. In a modification, Fig. 18; the drum 215 has sprockets 217, which 'engage the underside of the record and form indentations therein. Spring clips 220 or a casing similar to the casing 111 may be used to hold the overlapping ends of the record in position. The record may be wrapped around the drum either in the same way as is described with reference to Fig. 3, or by hand. In further modifications Figs. 20 and 22 (not shown) the record is held on the drum by spring-urged pins 'in the drum which engage slots or holes in the records Figs. 21, 23, (not.shown)..An indexing plate 195, Fig. 3, co-operates with a pointer 197 on the head 19. The magnetic head comprises legs 169, 170, Fig. 12, and a central T-shape leg 171. The leg' 169 has an' erase coil 172 and the leg 170 a high frequency bias coil 173 and a signal coil 174. The coils 172, 173 are connected in series to a H.F. oscillator 187 through a switch 187. The record comprises a body part 200, Fig. 14, of paper coated with ferro-magnetic material 201. U.S.A. Specification 2,351,004 is referred to