GB558528A - Automatic phonographs - Google Patents

Abstract

558,528. Automatic gramophones. PHILCO RADIO & TELEVISION CORPORATION. July 3, 1942, No. 9217. Convention date, Aug. 21,1941. [Class 40 (ii)] Relates to trip mechanism responsive to the quick movement imparted to the pick-up arm by the eccentric or quick pitch inner groove of record discs for initiating the record changing and pick-up return devices. According to the invention, an arm 11 rotating with the pick-up arm carries an insulated bracket 12 supporting a pivot 14 with a roller 16 and an electric contact arm 15. The arm 15 is biased by gravity and a light spring 20 to rest normally by means of a rubber cushion 19 on a set screw 18. During the inward travel of the pick-up, the roller 16 engages the under surface of a plate 22 and is thereby rotated to cause the contact 17 at the end of the arm 15 to approach the plate 22. But a cam 7 on the hub of the turntable periodically rocks a lever 24 pivoted at 25, and a set screw 27 at the end of lever 24 thereby periodically lifts the plate 22 off the roller 16, so that the arm 15 periodically moves back to its set screw stop 18 before the contact 17 can reach the plate 22. When, however, the quick movement of the pick-up arm occurs at the end of the playing of a record, the contact 17 reaches the plate 22 and closes the circuit of a solenoid 28. A lever 36 attached to the core of the solenoid is turned about its pivot 37, a roller 38 on one end of the lever 36 is withdrawn from locking engagement with a notch in a cam disc 29, and a clutch member 33 at the other end of the lever 36 is brought into engagement with a clutch member 34 on the hub of the turntable. Motion is then transmitted through gearing 32, 31, 30 to the cam disc 29, which makes one revolution and is then again locked by the roller 38. The rotation of the cam disc 29 serves to control any suitable record changing mechanism and to return the pick-up. A cam follower 43, 41 is attached by a spring 42 to the arm 11, which rotates with the pick-up arm. The cam disc 29 first lifts the follower 43, 41 which lifts the pick-up. Then the cam disc moves the pick-up out to allow the record changing to take place. Finally, the cam disc moves the pick-up arm inward over the edge of the fresh record and drops it on the starting groove. The pick-up arm may be operated by the mechanism described in Specification 556,974.