Patent GB-770094-A (GB)
Title: Improvements in and relating to automatic record changers
IPC: H02K7/118
Filed: 1955-05-23
Abstract: 770,094. Automatic gramophones. WEBSTER-CHICAGO CORPORATION. May 23, 1955 [July 29, 1954], No. 14864/55. Class 40 (2). [Also in Group XXIV] In a centre-post record changer for mixed diameter records in which indexing means are provided to control the setting-down position of the stylus, the machine is normally set for a record of the smallest diameter but when a record of larger diameter falls to the turntable it rotates a flag 90, Fig. 1, about a vertical shaft 93 carrying a cranked arm 87 which in turn rotates a shouldered cam plate 89 on a bracket 96 through the medium of a pin 88. Three steps shown on the cam plate 89, Fig. 5, correspond to the setting-down positions for three different size records. During an automatic cycle, the pick-up arm 30, Fig. 3, is fed over the turntable by a cam-lever 44 operated by a cam-disc 29 and frictionally coupled by a pad 73 to a shaft 60 carrying the pick-up arm 30 and a plate 63 bearing a pin 103 which engages the steps on the cam plate 89. The cam lever 44 also performs the function of lifting and lowering the shaft 60 and thereby the pick-up arm 30. In the lowered position, the pad 73 leaves the plate 63 so that the pick-up arm 30 is free to traverse a record. The arm 30 is mounted on shaft 60 by a pivot 68 and has a bracket 70 which hooks under a fixed bracket 71 when the shaft 60 is raised and thereby gives an upward tilt to the arm 30. The camdisc 29 is tooth-gear driven from the turntable sleeve 17 and has a recess 32a in which the sleeve 17 idles during the playing of a record. During playing an arm 78 frictionally coupled to shaft 60 moves a two-pronged lever 80, 81 counterclockwise against a member 83 on the cam-disc 29. The member 83 moves a pivoted plate member 39 slowly towards sleeve 17 which carries a protruding pin 37 which taps the plate 39 backwards until the run-off groove is reached. When this happens the pin 37 becomes positively engaged with plate 39 to give the camdisc 29 its initial rotation to start an automatic cycle. After the last record has been released on to the turntable an overarm 110 and its shaft 111 drop to their lowermost position and press down a spring-loaded lever 113 and a stop link 115 so that when the pick-up arm is next swung outwardly on the next automatic cycle, the pick-up arm is prevented from being fed inwardly again because link 115 is held in the path of a projection 117 on plate 63. When the lowering operation of the pick-up arm is then performed a hooked end 119 of plate 63 actuates a micro-switch 120 to interrupt the current supply to the motor. During playing of a record, an automatic cycle may be initiated by the pressing of knob 122 which through a linkage and a push rod 126, Figs. 2 and 3, moves an arm 128 and trips the two-pronged lever 80, 81. Knob 122 is also rotatable to three different positions to control the speed of the motor, by means of another push rod 150, Figs. 3 and 14, which moves a cam-slide 159, Fig. 11, which raises and lowers the rotor shaft 151 of the motor. the shaft 151 carries a stepped cone driving a jocket pulley 153 engaging the rim 11 of the turntable 10. Six steps are provided on the stepped cone so that three different speeds may be obtained on each of two different frequency supplies. The jockey pulley 153 is invertible, the inverting of the pulley having the effect of raising or lowering its rim by one step on the stepped cone, according to whether a 50-cycle or 60-cycle supply is being provided for. A link 170 couples the cam-slide 159 to a cranked shaft 168 which carries a notched plate 166 to move the jockey pulley away from the stepped cone while speed changing takes place.