Pickup circuitry for a video disc player with printed circuit board

Abstract

Stylus, having a conductive electrode, is mounted at one end of a pivoted stylus support arm within a pickup cartridge body of non-conductive material, removably received in a conductive housing. A conductive spring, with one end in electrical contact with the stylus electrode, is secured at its opposite end to the cartridge body. A printed circuit board, mounted within the conductive housing, comprises a dielectric substrate bearing a conductive coating in several elongated surface regions. The conductive coating in two of said regions defines first and second conductors, lying substantially parallel to each other. When the cartridge is received in the housing, electrical contact is established between the body-secured spring end and one end of the first conductor. Capacitive elements couple the other end of the first conductor to the housing. The spring, first conductor, and housing form a transmission line, which resonates with the end-loading capacitive elements and a variable capacitance formed between stylus electrode and the disc record, at frequencies in a selected range. UHF oscillations at a frequency adjacent said range are inductively coupled to the transmission line. AM detector, connected to second conductor, recovers recorded information.