Patent GB-1177458-A (GB)
Title: Improvements in and relating to Phonograph Apparatus
Inventor: NAKAJIMA YASUTAKA
IPC: G11B3/36
Filed: 1968-04-22
Abstract: 1,177,458. Phonograph record changers. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. 22 April, 1968, No. 18974/68. Heading G5R. A phonograph record changer comprises a chassis, a turntable mounted on the chassis, carriage means on the chassis movable along a path parallel with a radius of the record, a tone arm with a pick-up pivotally mounted on the carriage means, a rotatable drive means supported on the chassis, the drive means having its axis of rotation disposed parallel to the path of the carriage means, a detecting means for initiating a record-changing cycle in response to accelerated movement of the pick-up in the run-out groove of a record, a first means on the carriage for moving the tone arm to lift the pick-up from the record and to lower it on to the record, a second means on the carriage for coupling the carriage to the drive means (causing the carriage means to move along a path parallel with the axis of the drive means), and means for feeding a record to the turntable. Starting; tone arm traverse to record.-When the drive of turntable 56 is started, the turntable boss drives continuously by pulley 50 and belt 62, Figs. 2 and 25, a cylinder 36, and a gear 130, Fig. 25, formed on the boss drives intermittently, during the cycle, a large gear 148 having a cam on its upper surface. The tone arm assembly includes a roller 102, Figs. 2 and 3. At starting, linkage operated by the cam serves to orientate the tone arm assembly in a horizontal plane until the tone arm 32 is inclined to the axis of cylinder 36 in a direction such that stylus 31 is to the left of bracket 33, Fig. 1. The consequent inclination of roller 102 relative to the axis of cylinder 36 results in a component of motion, in the direction B, Fig. 3, being imparted to the carriage 78 on which the tone arm assembly is mounted. When, during this movement, a tone arm locating lever 350, Fig. 3, forming part of the tone arm assembly, makes contact with one of three abutments 404, 406, 408, Fig. 22, on a locating plate 322 (depending on the size of the record on the turntable), the tone arm is progressively rotated until it is perpendicular to the axis of cylinder 36 and tangential to the record groove. The stylus is now located above the starting groove of the record, and tone arm traverse ceases. Tone arm lowering, operative traverse and raising.-At this stage, linkage operated by the cam serves to lower the tone arm until the stylus touches the record. As the record rotates, the stylus moves inwards, but as soon as this movement inclines the tone arm 32 to the axis of the cylinder 36, a component of motion is imparted, through cylinder 36 and roller 102, to the carriage 78, which thereupon moves in the direction of arrow B until the perpendicularity is restored. The tone arm 32 is thus effectively driven by the cylinder 36 in this manner throughout its operative traverse. During the operative traverse the cam is at rest. When the stylus reaches the run-out groove of the record its increased inward speed serves to initiate further rotation of the cam, whereupon the tone arm 32 is raised and locked in the raised position. Tone arm return traverse.-The tone arm assembly is now orientated, by linkage operated by the cam, in the horizontal plane so that stylus 31 is to the right of bracket 33. The consequent reverse inclination of roller 102 relative to cylinder 36 results in the carriage 78 being driven to the right until the tone arm reaches rest 282, Fig. 1, whereupon the tone arm gradually resumes perpendicularity to cylinder 36 and the traverse ceases.. (The tone arm raising mechanism, and the mechanism and manner of return traverse, are very similar to those described in Specification 1,093,649.) Record release.-During the return traverse, the gear is not rotating, but after the tone arm has moved to its rest position, gear rotation is resumed. At this stage a pin 372, Fig. 25, fixed to the underside of gear 148, encounters a U-shaped dropping lever 312 and moves it slightly about its pivot 320. The lower portion 316 of dropping lever 312 has a slot which accommodates the lower end 146 of a rocking lever 140, so that when lever 140 is rocked by movement of lever 312, the lowermost record of a stack 136 is dropped on to the turntable 56, Fig. 25. Other features.-When the last record has been played, the locating plate 322, Fig. 22 (which tilts downwards to varying degrees for different sizes of record), tilts downwards to its maximum extent, so that the tone arm locating lever 350 is in contact with a fourth abutment 410 when the tone arm is in the rest position. Consequently, the tone arm cannot start its initial traverse towards the turntable, and the automatic cycle ceases. During play, playing a record may be interrupted by turning a hand lever. This serves to initiate resumption of the gear rotation which in turn serves to raise the tone arm and return it to the rest position automatically, as above described. Dropping of the next record then follows, also automatically. The mechanism is designed so that damage to the tone arm by a falling record is avoided by preventing descent of a record except when the tone arm has been returned to its rest position, or to a position beyond the outer periphery of the record.