Servo control for record player pick=up arm - has pivot allowing horizontal balancing about carriage with reflector

摘要

The record player has optical servo control system to monitor pick up arm to ensure that it remains perpendicular to radius of record disc. The record disc(4) is rotated by a motor driven platform (2). A point (7) on a pick up head (6) contacts grooves in the disc and is moved by an arm (5) with counterweight (8). A pivot (9) allows horizontal balancing about a carriage (10) on which an arm (15) carries a reflecting surface. A luminous source (20) provides radiation for the reflecting surface which is directed to a detector (23) whose signals drive a motor (33) via a printed circuit (30). A gearing (34, 35) to an endless screw shaft (36) permits positioning of carriage and pick up arm.