Velocity correction system with damping means

Abstract

One type of video disc reproducing system senses the capacitance between a stylus and a disc record to reconstruct the video information. The stylus includes a thin conductive element or electrode and rides in a groove of the record, which is rotated at high speeds. The record includes a conductive layer covered with a thin dielectric material. A velocity correction system comprising a closed-loop feedback system provides an advantageous means to vary the position of the pickup means relative to the moving record. This positioning maintains the relative velocity between the two substantially constant for a given radius from the center of rotation, thus correcting for residual velocity errors. There is disclosed a transducer apparatus which is mechanically coupled to the signal pickup means and electrically coupled to circuitry providing a velocity error signal. The transducer has a stationary portion which includes means for generating a magnetic flux. The transducer also has a second portion which is coupled to the pickup stylus and which is movable with respect to the stationary portion. The stationary and movable portions are intercoupled by compliant members. An electrical winding is disposed on the movable portion and is coupled by the magnetic flux such that an electrical current passed through the winding imparts motion to the movable portion. Electrical damping is provided by a closed-loop conductive member on the movable portion which is coupled by the magnetic flux and is operative to oppose motion of the movable portion.