Patent GB-536700-A (GB)
Title: Apparatus for use in recording sound
IPC: G11B3/08
Filed: 1940-02-22
Abstract: 536,700. Gramophones. DAVIES, H. Feb. 22, 1940, No. 3386. [Class 40 (ii)] A sound recording apparatus comprises a turntable, a recording cutter head adapted to be lifted and lowered and to be positively moved by a feed-screw geared to the turntable mechanism, and hand controlled means adapted to be successively operated so that one operation causes the drive of the feedscrew and the lowering of the recording cutter head and the next operation causes the feedscrew to stop and the recording cutter head to be raised and so on successively. Turntable driving mechanism. The heavy turntable 1, Fig. 1, is driven by a silent electric motor 3 through a friction pulley 4 engaging the rim of the turntable. Pick-up mounting and feed-screw. The cutter-head 5, Figs. 1 and 5, is carried by a balanced lever 6, pivoted at 7 to an arm 8 which can be lifted about an horizontal spindle 9 on a carriage 10. When the arm 8 is lowered as shown, the stylus is still held off the record disc by a spring blade 22 which overcomes another spring blade 25, these blades acting on opposite ends of the lever 6. The stylus is lowered on the record by the spring 25 when the spring 22 is lifted from the lever 6 by a spring controlled pin 23 as explained below. The pressure of the spring 25 is adjusted by means of a pin and screw knob 27. The carriage 10 is fitted with two levers 17, 20 on a spindle 18 and with a manually operated finger 21 co-operating with the lever 20. The lever 17 has a half nut 16 adapted to be engaged with the feed-screw 15 under the action of a spring around the spindle 18. When the arm 8 is raised, the lever 20 can be manually depressed to disengage the feed; and when the arm 8 is lowered, the same operation can be performed by the manually operated finger 9. Control of feed and cutter-head. This control is performed by means of cams on an horizontal shaft 48, Figs.. 3 and 4, adapted to be driven by worm gear 47, 46 when the spindle 41 of the worm 46 is clutched to a spindle 37 driven by a belt 39, Fig. 1, from the turntable spindle 2. Another belt 32 transmits a drive from the turntable spindle to a shaft 30 provided with a friction pinion 34 adapted to drive the feed-screw 15 when a friction wheel 35 feathered to this feed-screw is allowed to engage the pinion under control of the cam device. In the position shown, the feed-screw drive is out of action and the stylus off the record. A record having been placed on the turntable and the cutter-head having been adjusted to the desired starting position, operation is started by the depression of whichever of two push-buttons 75, 76, Fig. 3, is the higher. This causes a T-shaped lever 73, 73<SP>1</SP> to be swung about its pivot 74 from one extreme position to the other under control of a toggle spring 77. The arm 73<SP>1</SP> of the lever rides over a projection 69 on a lever 67 and thereby temporarily depresses the lever 67. The lever 67 is fast with another lever 65 rotatable on a spindle 64 and normally urged upwards by a spring 70. When the lever 67 is depressed by the operation of a pushbutton, the lever 65 is therefore also depressed and a pin 66 at its end is moved out of a notch 62 in a ring 61 on the shaft 48. At'the same time, another lever 71 also pivoting about the spindle 64 is urged downwards by a spring 72 coupling this lever to the levers' 65, 67 and presses the worm spindle 41 down to cause the spindle 41 to be clutched to the spindle 37. The clutch comprises a rubber ring 44 between seats 43,45 on the two spindles. The clutch transmits a drive to the cam shaft 48 which turns about half a revolution when the clutch is again freed by the uprising of the levers, 71, 65 on the arrival of another notch 63 in the ring 61 opposite the pin 66 on the lever 65 An auxiliary latch may be provided to prevent friction between the pin 66 and the ring 61 during this operation The half rotation of the shaft 48 causes a face cam 49 to deflect a lever 52 to allow the frictionwheel 35 to engage the friction pinion 34, whereby drive is transmitted to the feed-screw 15. Also, a profile cam 50 causes arms 56 pivoted at 57 to rise and lift a bar 60 which in turn lifts the pin 23, Fig. 5, thereby allowing the stylus to engage the record. When it is desired to stop recording again the higher of the two buttons is pressed down to cause the cam shaft 48 to be again driven for half a revolution to its original position. During this half revolution, cam 49 causes drive to feed-screw to be discontinued bv separation of friction wheel 35 from friction pinion 34, and cam 50 causes stylus to be raised from record by reason of pin 23 being allowed to fall. Remote control may be provided for the push-buttons. Final concentric groove on record. During the 'last half revolution aforesaid of the cam shaft 48, the cam 49 is timed to act first to stop the screw-feed, and the cam 50 is timed to cause the rise of the stylus after two or more further revolutions of the record, with the result that a circular groove is cut in the record at the end of the recording. When such.'a record is reproduced, the stylus will therefore not score further when the end of the recorded track is reached.