Importance

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Abstract

An electronic ON/OFF control system for use on a powered hand tool to ensure operator safety and ease of operation. The hand tool is driven either by an electric motor driven, flexible drive shaft or a source of pressurized air supplied to the hand tool through a supply line. A low power frequency is applied alternately to the hand tool and power supply line. Appropriate circuitry detects changes in the frequency of the applied signal caused by an operator grasping the hand tool and power supply line and the sequence in which the two components are grasped. If the hand tool is being grasped when the drive shaft or supply line is subsequently grasped a signal is supplied to a power control unit which actuates the power source for the hand tool. The power control unit maintains the hand tool energized after releasing of the operator's grasp on the on the power supply line and automatically de-energizes the hand tool upon the operator releasing his grasp on the hand tool.

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First Claim