Patent GB-439106-A (GB)
Title: Improvements in and relating to automatic record changers for gramophones
IPC: G11B17/16
Filed: 1934-04-19
Abstract: 439,106. Magazine gramophones. COMPARE, A., 26, Alandale Drive, Pinner Hill, Pinner, Middlesex. April 19, 1934, No. 11806. [Class 40 (ii)] Relates to magazine gramophones in which records which may be of three or more different diameters are supported on a post above the turntable in any order, and aro released singly for playing. According to the invention, as each record passes down from the post to the turntable it brushes past and displaces one or more feelers located in its path, the extent of the displacement of the feelers into one of at least three positions corresponding to the size of the record, means being provided for moving the pick-up arm inwards to an extent controlled by the displacement of the feelers so that the pick-up is properly positioned for starting the playing of the record. In the machine shown, the post on which the records are supported, Figs. 4, 6, 6<b>, comprises two members 112, 218, mounted on a pin 112<a> fixed to a bridge structure 111, the part 112 being a forked rod which is fixed and encloses a slotted limb of the part 218. This is shaped as a bell-crank lever pivotally movable on the pin 112<a>, and its lower end has an offset base 113. Within the slot in the part 218 is a lever 118, also pivoted at 112<a>. The three parts 112, 118, 218 are aligned to form a smooth stem when an abutment 217 on a spindle 214 is turned by a handle 215 into the position shown in Fig. 6, and the records may then be readily threaded on, being supported on the base 113 when the abutment 217 is moved up as shown in Fig. 4. When the lever 118 is rocked as subsequently described, its toe 119 pushes the lowest record off the support 113. Feelers or gauge arms 177 are pivoted at 179 on oppositely disposed upright parts of the bridge structure, and are connected by wires 219 and a bell-crank lever 220 to the spindle 214, so that the arms 177 are raised when the abutment 217 is turned to enable the records to be threaded on the post. Each gauge arm 177 is connected to a vertical rod 180, Figs. 4 and 11 respectively connected to one of a pair of bell-crank levers 181 which are linked by a rod 184. Movement of the arms 177 causes a fork 186 to set a lever 188 into a position determined by the amount of movement of the arms, which is dependent on the size of a record passing down between the arms to the turntable. The lever 188 coacts with the mechanism serving to swing the pick-up arm for repositioning after the playing of a record, this mechanism being driven by a main shaft 122. The motor (not shown), that drives the turntable also drives a pinion 121, Fig. 11, loosely mounted on the shaft 122, and this pinion is adapted to be coupled to the shaft through a clutch comprising a ratchet wheel 124 secured to the pinion and a pawl 126 mounted on an arm fast on the shaft. An arm 131 normally holds the pawl out of engagement with the ratchet-wheel, so that the shaft 122 is stationary. The shaft carries a bevel wheel 157, gearing with a wheel 157<1> mounted on a short vertical shaft which carries a plate 160. This plate has pivoted eccentrically thereon a bell-crank lever 163, which is urged by a spring 164 so that a pin 166 thereon tends to move clockwise, Fig. 11. The pin 166 lies within a frame 136 which is fixed to a vertical tube 135 to which the pick-up arm 133 is attached. The tube is so mounted on journals in an upright part of the bridge 111 that the assemblage comprising the pick-up arm, tube 135, and frame 136 can rotate about vertical and horizontal axes. The bell-crank lever 163 carries a second pin 165 adapted to engage with the lever 188, which has an extension carrying a rack 189. This is engaged by a pawl 191, which serves to hold the lever 188, against the action of a spring, in any position in which it is set by movement of the gauge arms 177. The operation of the machine is as follows. Assuming that a record is on the turntable and is being played, as the pick-up arm 133 moves, the frame 136 rotating with it operates a lever 137, Fig. 11, carrying on a pivoted arm 143 a lug 144, which coacts with a member depending from the turntable; the arrangement is such that when the needle enters the run-off groove in the record the arm 143 swings the arm 131 clear of the pawl 126. Thus the main shaft 122 is coupled to the motor through the clutch 124, 126. The raising of the pick-up is brought about by a cam 148 on the shaft 122 operating mechanism which tilts the frame 136 and so rocks the tube 135 and the pick-up arm about the journals on which they are mounted. At the same time, the gauge arms 177, which remained depressed during the playing of the record, are allowed to rise, the pawl 191 being moved away from the rack 189 by means of a lever 198 actuated by the shaft 122. The outward movement of the pick-up arm is next effected by the engagement of the pin 166 with the part 167 of the frame 136. The bottom record in the stack is then released from the magazine post by movement of the finger 118, which is effected by a cam 176 on the shaft 122 acting upon mechanism 175, 170,168 connected to the finger, Figs. 4 and 11. As the record falls, it displaces the gauge arms 177 which, in accordance with the extent of their movement, control the position of the lever 188, Fig. 11, by which the return movement of the pick-up arm is limited. This return is brought about during the completion of the revolution of the bell-crank lever 163, by the engagement of the pin 166 with the part 185 of the frame 136, the inward movement of the pick-up arm ceasing when the pin 165 is obstructed by the lever 188. Finally the cam 148 allows the pick-up to be lowered on to the record, and another cycle of operations begins with the playing of the fresh record, the main shaft 122 having meanwhile been stopped, after completing one revolution, by engagement of the pawl 126 with the arm 131. A rod 219, which can be moved into various positions by means of a knob 225, Fig. 11, is adapted to control the members 175, 131, and 198, to enable the playing of a record to be repeated, or to cause a record being played to be rejected at any time. In order to switch off the motor as soon as all the records have been played, two switches 199,200, Figs. 4 and 6<a>, are provided in parallel in the motor circuit. The switch 200 is controlled by a pair of spring-controlled arms 202 which are pivoted together like scissors at 203, their outer ends bearing pads 205 which rest on the top record. When the arms fall to their lowermost position, on the release of the last record, one of the arms allows a trigger lever 208, Fig. 6<a>, to move and release a bar 212 by which the contacts of the switch 200 are normally held closed, so that the switch is thereupon opened. The switch 199 is controlled by a cam 201 on the main shaft 122, and is opened when the pick-up arm has been swung outwardly. Thus the motor circuit is finally broken.