Patent GB-478389-A (GB)
Title: Improvements in or relating to sound reproducing machines provided with a repetition device
IPC: G11B3/08
Filed: 1936-11-19
Abstract: 478,389. Gramophones. ROUTIN, J. L. Nov. 19, 1936, Nos. 31752, 31753, 31754, and 31755. Convention dates, Nov. 23, 1935, March 31, 1936, April 30, 1936, and Oct. 5, 1936. Addition to 460,897. [Class 40 (ii)] Relates to gramophones adapted for selection and repetition of a predetermined part of a disc record, as described in the parent Specification, and consists of improvements of various parts thereof, in particular an improved cam for controlling the position of the pick-up arm, a lever mechanism for adjusting that cam, a pawl and ratchet mechanism driven chronometrically for controlling the cam that operates the lifting of the pick-up arm, and a spring hammer device for opening the box of needles. As shown in Fig. 1, the pick-up arm b is pivoted at c on the rotatable pillar 10, and keyed by a finger 12 and slot f to an arm d formed with a knife edge e acting as a supporting fulcrum for the pick-up arm when this is lifted from the record. The notch of the adjustable cam 13 is now made with both sides 15, 115 inclined, and the finger 12 always lies above part of this notch, so that when the pillar 10 falls and lifts the pick-up, the finger 12 rides down to-the bottom of the notch, and the pick-up arm is thus returned to over the restarting position determined by the position of the cam 13. The cam 13 is provided with a lever 117, and this, as shown in Fig. 7, is adjusted against a graduated toothed sector 118. A pawl 123 is pivoted on the end of the lever 117 to engage the toothed sector to hold the lever in the adjusted position. The pivot of the pawl 123 is an eccentric 151, which can be rotated for fine adjustment by means of a milled head. Further fine adjustment is provided by a cam rotated by a milled knob 128 to adjust the sector 118. The cam 50 controlling the lifting and lowering of the pickup arm is now provided with a double-armed pawl 53, Figs. 2 and 3, pivoted on the cam at 56 and adapted to engage a ratchet wheel 48 formed' with N teeth and adapted to be driven one revolution when the record makes N revolutions. The ratchet wheel is fast with a pinion 49 with which a toothed wheel 64 can be put in and out of mesh, this wheel being mounted on a spindle 63 on a bracket 61 pivoted at 62 and urged by a spring 66 towards the pinion 49. When the wheel 64 is disengaged from the pinion 49, it is rotated by a spring 65 in a counterclockwise direction until a pin 74 on the wheel 64 abuts against an arm 75 set (according to the length of the part of the record to be reproduced) by means of a handle and worm gear 78, 77 to a position indicated by a graduated drum 79. Starting from this position, when the wheel 64 is put in mesh with the pinion 49, it is driven in a clockwise direction until a pin 73 on the wheel strikes the arm 58 of a bell-crank lever 57, 58 pivoted at 59. The lever rocks and releases the end 55 of the double-armed pawl 53, which is urged in a counterclockwise direction to bring its end 54 into engagement with the ratchet wheel 48, thereby causing the cam 50 to follow the counterclockwise rotation of the ratchet wheel. A pin 70 on the cam 50 now pushes a rod 67 to the right, and this rod being jointed at 68 to the bracket 61, the wheel 64 is moved out of mesh with the pinion 49 and returned by the spring 65 to its starting position. The rod 67 is held back by a stop 71 until the cam 50 has made one revolution when the pin 70 engages an extension 69 of the rod 67 and lifts this rod off the stop 71, whereupon the wheel 64 is again put in mesh with the pinion 49. Immediately after this the end 55 of the pawl 53 is arrested by the arm 57 of the bell-crank lever and the end 54 of the pawl withdrawn from the ratchet wheel. The above operation is then repeated. Alternatively, the bell-crank lever might be electromagnetically operated periodically. When it is desired to repeat the whole record, a knob 93 is turned to allow a spring catch 89 to engage an arm 85 on the bracket 61 to hold the wheel 64 out of mesh with the pinion 49, and the bell-crank lever 57, 58 is then rocked at the end of the record by a cam 81 on an arm 80 following the movement of the pick-up arm. The cam is adjusted by a knob 82 to operate when the needle has reached the last groove of the record. The driving motor M is fed from terminals 94 through two switches in parallel, a switch 95 operated by a hand lever 96, and a switch 87 operated by the arm 85 of the frame 61. So long as the switch 95 is closed, repetition goes on. If the switch 95 is opened while the switch 87 is closed, the operation continues until the selected part of the record is completed when the pin 73 rocks the bell-crank lever 57, 58 and the wheel 64 is disengaged and the switch 87 simultaneously opened. In an alternative switching arrangement, Fig. 4, a switch 271 normally closed is arranged on a lever 265 pivoted at 266 and provided with a finger 267. The lever can be adjusted to three different positions determined by the co-operation of a spring catch 268 with pins 269, 270 on the lever. When the lever is in the central position shown, finger 267 is in the path of the end 55 of the double-armed pawl 53 during the rotation of the cam 50 by the ratchet wheel 48. The repetition mechanism is then stopped after the pick-up arm is lifted at the end of a selected part of the record, but the switch 271 remains closed and the motor continues to operate. When the upper end of the lever is swung to the right, the finger 267 is moved out of reach, and repetition proceeds uninterruptedly. And when the upper end of the lever is swung to the left, the repetition mechanism is stopped as when the lever is in the central position, and in addition the motor is stopped by the opening of the switch 271 by a bell-crank lever 272 rocked by the cam 50. A knob 276 is provided on the bell-crank lever 57, 58 so that this lever may be operated by hand to make a return to the beginning of a selected passage at any time. Another modification comprises a second ratchet wheel, integral with and adjacent to the ratchet wheel 48, and formed with a larger number of teeth. The end 54 of the pawl 53 first engages this second ratchet wheel and the spindle 56 of the pawl is then displaced by a fixed ramp to make the end 54 engage the ratchet wheel 48. A further modification comprises an additional cam on the spindle of the cam 50 to control a brake to hold the pick-up arm against lateral movement while the needle is being lowered back on to the record. In another improvement, Fig. 10, a hammer 137 at the end of a spring arm 136 on a lever 133 controlled by a spring 135 is gradually cocked by a cam 132 driven by the motor of the gramophone and is released by the cam after a given run to strike a catch 39 to release a cover 44 of a needle box 43. The opening of this box might be used to control the motor. The cover when closed down again is locked by the catch- 39 under the influence of a spring 42. The box 140, Fig. 12, containing the gramophone mechanism has a hinged lid 141 carrying an electric lamp 142 on a bracket 143 controlling a switch 144. The lamp is supplied through the hinge 145 and the link 146 and through leads wound .up on spools 147, 148.