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. 09, 1989
Filed:
May. 29, 1987
James R Hack, Villa Park, CA (US);
Sanders Associates, Inc., Nashua, NH (US);
Abstract
A plurality of switched voltage sources (10, 10', 10') apply charge to a sheet of paper (16) by way of respective sets of styli (12, 12', 12'). To print a dot when toner is subsequently applied to the paper, the voltage source (10) deposits charge on the paper (16) by applying a high voltage, and its voltage returns to ground when it is to avoid leaving a mark. In order to avoid the image degradation that results from the proximity of an unenergized stylus to an energized one, a zener diode (14) is interposed between the switched voltage source (10) and its respective styli (12). By virtue of stray capacitance (C.sub.s) between the styli (12) and ground, the potential of the styli does not return completely to ground when their respective voltage source is switched off. Instead, it returns only to the zener voltage, and this reduces the image degradation that the presence that the unenergized styli would otherwise cause.