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:
Sep. 24, 1991
Filed:
Aug. 29, 1988
James M Robitaille, Cleveland, OH (US);
Ericson Manufacturing Company, Willoughby, OH (US);
Abstract
A plug-mounted wriststrap detector and ground monitor includes hot, neutral and ground input terminals which are connected to corresponding terminals of a power outlet when the circuit is plugged in. A jack is provided to plug a wriststrap into the circuit to provide electrostatic protection to the user. Means are provided to detect that the user is wearing the wriststrap and that the wriststrap is properly connected to the circuit as a function of whether an a.c. signal of sufficient amplitude is detected coupled to the circuit by the wriststrap and/or user. Lamps and an audible alarm warn the user if the wriststrap is not properly connected. A precision ground integrity circuit is provided to detect whether an unsafe ground condition exists and to alert the user accordingly. The ground integrity circuit uses a constant current source and voltage comparator to determine that the ground impedance does not exceed a predetermined limit.