The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 01, 1979
Filed:
Feb. 27, 1978
Gary W Hughes, Princeton, NJ (US);
Hirohisa Kawamoto, Princeton, NJ (US);
RCA Corporation, New York, NY (US);
Abstract
Stylus suitable for use in a capacitive disc record playback apparatus comprises a wedge-shaped support material and an electrode formed on a flat longitudinal surface of the support material. Signal pickup qualities of such stylus can be determined by supporting such stylus on a silicon dioxide-silicon wafer where the capacitance formed between the electrode bottom and the wafer can be changed at a cyclical rate by energizing the wafer with a low frequency signal. A tuned resonator circuit coupled to the electrode detects those capacitance variations and additional undesired capacitance variations contributed by fringe capacitance between the whole of the electrode and the wafer. Where the wafer is of an n-type silicon material, the contribution of the fringe capacitance to the detected capacitance variations is reduced by growing a large quantity of positive charge in the silicon dioxide layer of the wafer.