Method for forming a narrowed-electrode pickup stylus for video disc systems

Claim 1

A method of fabricating a narrowed-electrode stylus by modifying a tapering dielectric support element having a tip which is defined by a prow and a substantially flat V-shaped rear surface remote from said prow; the entire rear surface of said dielectric support element being covered with conductive material to form an electrode; said narrowed-electrode stylus being suitable for playing back prerecorded signals from a disc record groove of a given width and a given pitch; said method comprising the steps of: introducing said tip of said tapering support element in an abrasive groove having a bottom wall, substantially parallel side walls separated by a distance less than said given width and lands extending away from said side walls; while establishing relative motion between said tapering support element and said abrasive groove along a line which is disposed in a plane substantially perpendicular to said V-shaped rear surface; gently tilting said electrode face of said support element toward said abrasive groove until it subtends a shallow angle with the bottom wall of said abrasive groove to form a portion having an arrowhead-shape cross-section in the region of said tip; the apex of said arrowhead-shape cross-section being located on said prow; the base of said arrowhead-shape cross-section being defined by said substantially flat rear surface; said lands of said abrasive grooves forming the shoulders of said arrowhead-shape cross-section; said side walls of said abrasive groove forming the sides of said arrowhead-shape cross-section interconnecting said shoulders and said base of said arrowhead-shape cross-section; and terminating said relative motion subsequent to formation of said tip portion having an arrowhead-shape cross-section.

Claim 2

A method of fabricating a narrowed-electrode stylus by modifying a tapering dielectric support element having a tip which is defined by a prow and a substantially flat V-shaped rear surface remote from said prow; the entire rear surface of said dielectric support element being covered with conductive material to form an electrode; said narrowed-electrode stylus being suitable for playing back prerecorded signals from a disc record groove of a given width and a given pitch; said method comprising the steps of: introducing said tip of said tapering support element in an abrasive groove having a bottom wall, substantially parallel side walls separated by a distance less than said given width and lands extending away from said side walls; while establishing relative motion between said tapering support element and said abrasive groove along a line which is disposed in a plane substantially perpendicular to said V-shaped rear surface; gently tilting said electrode face of said support element toward said abrasive groove until it subtends a shallow angle with the bottom wall of said abrasive groove to form a portion having an arrowhead-shape cross-section in the region of said tip; the apex of said arrowhead-shape cross-section being located on said prow; the base of said arrowhead-shape cross-section being defined by said substantially flat rear surface; said lands of said abrasive grooves forming the shoulders of said arrowhead-shape cross-section; said side walls of said abrasive groove forming the sides of said arrowhead-shape cross-section interconnecting said shoulders and said base of said arrowhead-shape cross-section; and terminating said relative motion subsequent to formation of said tip portion having an arrowhead-shape cross-section.