Playback apparatus for electrostatically recorded signals

Claim 1

IN APPARATUS FOR THE PLAYBACK OF INFORMATION FROM ELECTROSTATICALLY RECORDED DIELECTRIC MEDIUM COMPRISING, IN COMBINATION, A FRONTAL SIGNAL SENSING ELECTRODE, AN OPPOSED BACKING ELECTRODE, MEANS FOR PASSING BETWEEN SAID ELECTRODES A DIELECTRIC MATERIAL WHICH CONTAINS ELECTROSTATIC CHARGES CORRESPONDING TO AN ELECTROSTATICALLY RECORDED SIGNAL WHEREBY TO INDUCE IN SAID ELECTRODES AN ELECTRIC SIGNAL OF AN ELECTROMOTIVE FORCE PROPORTIONAL TO SAID CHARGES, AND AMPLIFIER MEANS EFFECTIVE TO AMPLIFY SAID INDUCED SIGNAL, THE IMPROVEMENT WHICH COMPRISESA A FRONTAL ELECTRODE OF LAMINAR CONSTRUCTION COMPRISING A CENTER ELECTRODE LAMINA, AN ELECTRICALLY CONDUCTIVE SHIELD LAMINA ON EACH SIDE OF SAID CENTER ELECTRODE LAMINA, AND AN INSULATING BARRIER LAMINA OF DIELECTRIC MATERIAL BETWEEN EACH SHIELD LAMINA AND THE CENTER ELECTRODE LAMINA, SAID BARRIER LAMINAE AND THE CENTER ELECTRODE LAMINA TOGETHER PROVIDING A FIXED GAP BETWEEN SAID SHIELD LAMINAE, SAID GAP HAVING A WIDTH LESS THAN 0.002 OF AN INCH, AND MEANS TO CONDUCTIVELY COUPLE SAID CENTRAL ELECTRODE AND SAID SHIELD LAMINAE TO SAID AMPLIFIER MEANS.