Patent GB-672792-A (GB)
Title: Magnetic sound recorders
Inventor: SCHROTER EDWARD
IPC: G11B23/087
Filed: 1949-06-27
Abstract: 672,792. Magnetic recording and reproducing apparatus. GRACE ELECTRONICS. Inc. June 27, 1949. No. 17021/49. Class. 40 (ii). A magnetic sound recorder comprises rotatable winding and rewinding turntables adapted to receive the reels of a magnetic recording tape which is fed from one reel to the other, and to be driven by a friction driving wheel mounted on one arm of a lever intermediate the winding and rewinding turntables, while the other arm is resiliently engageable with a pivoted actuating arm mounted over it selectively to move said friction driving wheel into and out of resilient frictional rotary engagement with one or the other of the turntables by movement of the actuating arm about its pivotal axis. The apparatus is mounted in a casing 2, the rear upper part 6 of which may be hinged back for the removal of a magazine 8 containing the tape reels 148, 149 which engage over centre pins 86, 90, and drive pins 89, 94 of turntables 80. 81 which project through a cover plate 144. A recessed panel board 12 mounted over a loud speaker 10, carries a switch and tone control 13, volume control 14, sockets 15, 16 for microphone or earphones, and a multiposition control lever 22 movable in slots 17-21. A roll top cover 23 is provided. Inside, the casing is divided into two compartments by a platform 3 below which is mounted a motor 30 connected by friction gears 32, 33, 39 to a pulley 46 which drives through a clutch a tape-driving capstan 53. Pulley 46 is also connected by a belt to a friction driving wheel 82 which is mounted on a bell-crank lever 106 pivoted at 107. Lever 106 may be turned anticlockwise or clockwise from the position shown to cause driving wheel 82 to engage respectively a drum (not shown) arranged below and having positive driving connection with turntable 80, or a drum 91, Fig. 3, frictionally coupled with turntable 81, both turntables rotating anti-clockwise when driven. Control lever 22 comprises a main part which is rotatable in a horizontal plane about a pivot 140 and can also move in a vertical direction, and an extension 141 pivoted to the main part at 143, which rotates about 140 in a horizontal plane only. When lever 22 is moved to left or right, extension 141 moves a bar 120, Fig. 4, endwise which, through a shaped slot 135 engaging a, pin 113, turns bell-crank lever 106 and moves driving wheel 82 so as to drive turntable 80 or 81 respectively. At the same time rollers 123, 124 move aside to release brakes 130. 133, the arrangement being such that the brake on the driven drum is released slightly in advance of the other so as to take up any slack in the tape. Also a pin 203, Fig. 5, on lever 22 which projects through an opening in extension 141 coacts with a spring extension of an arm 196 pivoted at 197 so that when pin 203 is moved to the left, arm 196 moves anti-clockwise causing a roller 169 to press the recording tape 160 firmly against the drive capstan 53. This allows a spring-urged roller 168 to press the tape against a recording head 187. When lever 22 is depressed it engages a pin 182 on a lever 179 so that subsequent movement to the right moves an erasing head 170 into operative position. When lever 22 is moved upwards, its inner end is depressed and operates lever 99, Fig. 3 to give a positive drive between drum 91 and turntable 81. In use, for recording, the tape reels are in position, the tape being initially on reel 148, and threaded round rollers 166 ... 169 and joined. to reel 149. The motor is switched on to drive capstan 53 and wheel 82. Lever 22 is depressed and moved to the right into slot 21. This through pin 203 causes roller 169 to press the tape on to drive capstan 53, and roller 168 to hold the tape against the recording head 187. Also pin 182 causes the erasing head 170 to move into the operative position. At the same time bar 120 moves to the left to cause wheel 82 to drive turntable 81 and remove the brakes 130, 133. The rate of drive is determined by the capstan 53, the reel 149 tending to be driven at a faster rate through a slipping clutch, thus taking up the slack. For winding back, lever 22 is moved into slot 18. Pin 203 moves to the right removing the pressure of rollers 168, 169 on the tape. The erasing head is also withdrawn. Also bar 120 moves to the right to cause turntable 80 to be driven to wind back the tape at full speed. For playing back, lever 22 is moved into slot 20, to cause the tape to be fed through as for recording except that the erasing head 170 is left inoperative. For running through part of the tape without playing it, lever 22 is moved up into slot 19. This feeds the tape through at high speed since the depressed inner end of lever 22 engages lever 99, Fig. 3 to give a positive drive to turntable 81. Also, pin 203 is below and out of range of spring 201 thus allowing spring 198, Fig. 5, to remove rollers 168; 169 from the tape which is also lifted clear of the recording head by a finger 199. For momentary interruptions in recording without stopping the rest or the mechanism, a magnet 67, Fig. 5, is energized to cause an arm 71 to disengage a clutch and hold capstan 53 stationary. An indicator disc 210 pivoted under the lid of the magazine 8, Fig. 3, and visible through a window 212, Fig. 2, is driven by a friction wheel 219, Figs. 4 and 5, of a flexibly mounted gear train driven by a wheel 215 pressed against the tape.