US 5,686,897 A · Self-testing electronic grounding device

Abstract

A self-testing electronic personnel grounding device (wrist strap) for the purpose of dissipating static electricity from an individual. It uses a built-in electronic circuitry to detect a break in the electrical continuity in the wrist strap and alerts the wearer when there is a break in electrical continuity owing to broken connections along the dual wire coil cord or at the adjustable elastic wrist band, when it is improperly worn, or when the wearer's body resistance is too high. This device operates on a watch (Nickel-Cadmium, NiCd) type battery to provide the energy source to light an LED (Light emitting Diode) to indicate that there is a break in electrical continuity. The electronic circuitry is designed such that if the wrist band is improperly worn, causing ineffective contact between the human skin and the conductive side of the wrist band, the LED indicator will come on signaling a break in electrical continuity. The circuitry was also designed to be foolproof and also to conserve battery power to last for over one year of normal use and to allow the LED to dim off to alert the user that the battery is running out. This self-testing circuitry uses a dual wire coil cord to provide a closed loop electronic circuit.

Claims19

Dependent claims

A self-testing grounding device comprising:

a conductive strap physically attached to a circuit unit to form a wristband;
a conductive cord with one end electrically connected to said circuit unit with a removable plug, and the other end electrically connected to a voltage potential, wherein;
said circuit unit has an internal power supply, and also an external warning device that will turn on if said wristband becomes disconnected to said voltage potential,
wherein said conductive strap and said circuit unit are electrically separated by a variable electrical resistance,
wherein said conductive cord comprises two parallel wires, respectively connected to said conductive strap and said circuit unit on one end, and to said common voltage potential on the other end, wherein, of each of said two parallel wires, one is connected to a gate of a field effect transistor through said variable resistance and through a conductive plate located on said circuit unit, and the other is connected to the source and base of said field effect transistor.

2 more elements

Dependencies are inferred from the claim text.

Self-testing electronic grounding device

Life of this patent

Self-testing electronic grounding device

Life of this patent

Abstract

Claims19