Bearing arrangement for a record player tonearm

Abstract

The disclosed arrangement is of the type for a short tonearm which is guided over the record so that the tonearm remains tangential to the grooves of the record. The tonearm is balanced mechanically on a single point bearing, with the phono cartridge to one side and a counterweight to the other side of the bearing. A permanent magnet fixed to the top of the tonearm interacts with a stationary magnet closely spaced from it to hold the tonearm vertically. The tonearm magnet is a vertical, round, solid cylinder section, while the stationary magnet is a parallelepiped with facing width equal to the diameter of the facing tonearm magnet. This constrains the tonearm to prevent it from tipping to the side, while permitting rotation about the vertical axis and about a horizontal axis through the point bearing and perpendicular to the tangent to the record groove. The improvement comprises that the stationary magnet is provided with a winding. By control of a direct current in the winding, the tonearm can be raised and lowered and the stylus pressure controlled, even while the stylus is tracking in a groove. Futhermore, the tonearm can be magnetically preloaded, so that in the absence of current in the control winding, the tonearm raises to its rest position, thus preventing damage to the record. Various designs are described for determining the interaction of the movable and stationary magnets and the superimposed magnetic field of the control winding.