Patent GB-421638-A (GB)
Title: Improvements relating to automatic gramophone-record reproducing apparatus
IPC: G11B17/04
Filed: 1933-06-15
Abstract: 421,638. Gramophones. COLLARO, C., 84, Portsdown Road, Maida Hill, and COLLARO, Ltd., Culmore Road, Peckham, both in London. June 15, 1933, No. 28492 /34. Divided out of 421,575. [Class 40 (ii)] Relates to gramophones of the kind having means for bringing the pick-up or sound-box automatically into position to begin playing. According to the invention, (which is particularly applicable to a gramophone having a lateral slot in the casing, through which the records are inserted for playing without opening the casing, as described in Specification 406,311), the pick-up or sound-box is brought into the proper position on or above the edge of a record by a pusher or " selector member which, prior to the playing of each record moves for a predetermined time, and the path of which is controlled during the said movement by a cam which is adjusted in accordance with the size of the record, so as to vary the effective stroke of the selector member correspondingly. At the conclusion of the playing of each record, the pick-up or sound-box is moved outwards through a distance greater than the radius of the largest record for which the machine is designed, and it is moved inwards to the appropriate position, when the next record is used, by the cam-controlled action of the selector member. The Specification describes and shows the application of the invention to a machine which is the same as that described in Specification 421,575. As therein described, a bell-crank 44 is fixed to the stem of a record-carrier arm, not shown. Pivoted on an arm of the bell-crank is a bar 52 (referred to as a " selector bar "), which has a hooked end 107 near which is slidably mounted on the bar a plate 131 having a stepped edge 54. A spring 132 connects the plate 131 to the selector bar. The spindle on which one of the roller-carrying arms of the gate is mounted (as described in Specification 421,575) also carries an arm 49 which is connected by a link 48 to a pivoted cam 50, coacting with a pin 51 on the bar 52 ; a spring 53 holds the pin in contact with the cam 50. When a record is thrust into the slot of the casing, and passes through the gate, the latter is opened to an extent depending on the size of the record. By means of the mechanism 49, 48, the position of the cam 50 is adjusted accordingly, and this determines the position of the selector bar 52. Thus, when the cam drum 27 rotates and, through the bell-crank 44, moves the bar 52 to the position shown in chain lines, the appropriate step 54 is brought into engagement with a pin 55 on an arm 56 rigid with the pick-up arm, and moves the pick-up arm inwards through the necessary distance (i.e. until it is over the margin of the record then in use). The pick-up arm is meanwhile held up by means of a thrust rod 60 located in the pick-up arm bearing 61, Figs. 11 and 12. The rod 60 bears against an abutment screw 63 on a lever 62 which passes through a slot 121 in a spring-controlled bar 57, an end of which engages a cam surface 59 on the drum 27. When the pick-up arm is due to be lowered, the cam 59 allows the bar 57 to move towards the centre of the cam drum, so that the slot 121 shifts the lever 62 over to the chain-line position, Fig. 12, and the abutment 63 allows the rod 60, and thereby the pick-up arm, to be lowered. The swinging and lowering movements of the pick-up arm during the setting operations are damped by frictional and dash-pot devices respectively. The yieldable mounting and the spring control of the stepped plate 131 provide means for urging the pick-up needle from the smooth margin into the sound-groove of the record. After the record has been played, and during the second half-revolution of the cam drum, which is effected as described in Specification 421,575, the bar 57 is moved back by the cam 59, and causes the pick-up arm to be raised by the action of the parts 62, 63, 60. The selector bar 52 is then moved back by the bellcrank lever 44 to its original position, and in so moving, the claw 107 engages the pin 55 and swings the pick-up arm outwards. The shape of the claw is such that it does not prevent the pick-up arm from being swung out manually through a side opening in the casing (provided as described in Specification 421,639), when it is desired to change the needle. During the return movement of the bar 52, a bevelled face 164 of a projection 165 carried by the bar engages a pin 91 on a member 93 of the clutch-operating mechanism, to reset it to the normal position. Resetting of the release mechanism operated by the pick-up arm is effected by a pin on the bar 57. In addition to the mechanism described in Specification 421,575 for operating the clutch-bar at the end of the playing of a record, a modification comprising an auxiliary delay device is described (Fig. 16 not shown), for ensuring the required functioning of the device whereby the cam drum controls the clutch bar.