Patent ID: 7784104

Claim:
A power tool system comprising: a power tool configured to be manipulated by a user and to include a controller which enables said power tool only upon receiving an authentication signal; a wearable piece provided as a separate entity from said power tool and configured to be worn by said user; a certification unit configured to store an identification code specifying said power tool and to transmit said identification code; and an authenticator configured to read said identification code from said certification unit and to provide said authentication signal to said controller when said identification code is authenticated to be eligible for a privileged use of said power tool; wherein said power tool incorporates one of said authenticator and said certification unit, while said wearable piece incorporates the other of said authenticator and said certification unit; said system includes communication means which is configured to establish a communication between said certification unit and said authenticator for transmission of said identification code therebetween, while the user holds said power tool with said wearable piece carried on, wherein said communication means is configured to use the user's body as a signal transmission path, and wherein said communication means comprises a first transceiver incorporated in said certification unit, and a second transceiver incorporated in said authenticator; and, said first transceiver including: a signal electrode configured to be held in close proximity to the user's body; a ground electrode configured to be held close proximity to the user's body in a spaced relation from said signal electrode; and a transmitter configured to apply a voltage signal indicative of said identification code across said signal electrode and said ground electrode; said second transceiver including: a circuit ground configured to be connected to the ground through a casing of said power tool; a touch electrode provided on a grip of said power tool for contact with the user's hand; and a signal detector configured to be connected across said touch electrode and said circuit ground for detection of said voltage signal.