Apparatus and method for restricting the discharge of fasteners from a tool

A tool for discharging fastening devices comprising:

• means for discharging the fastening devices;
• means for determining when the fastening devices are to be discharged, wherein the determining means is coupled to the discharging means;
• means for generating an oscillatory signal, wherein a resonant frequency of the oscillatory signal depends both upon characteristics of the generating means and also upon a material proximate at least one portion of the generating means, and wherein the generating means is supported by the discharging means;
• means for detecting a frequency of the oscillatory signal and producing a first signal indicative thereof, wherein the detecting means is electrically coupled to the generating means;
• means for producing a second signal indicative of a quality factor of the oscillatory signal, wherein the quality factor depends at least in part upon the material proximate the at least one portion of the generating means, and wherein the producing means is coupled to the generating means;
• and
• means for providing a third signal to prevent the determining means from causing the discharging means to discharge at least one of the fastening devices, wherein the third signal is provided in response to the first and second signals.

A method of preventing a tool from discharging a fastening device into human flesh, the method comprising:

• exciting a resonant tank circuit having a coil with an electrical signal to produce an oscillatory signal within the resonant tank circuit and an electromagnetic field that envelops a material that is proximate the coil, wherein the electrical signal is continually adjusted to be at a resonant frequency of the resonant tank circuit as affected by the material;
• generating a frequency signal indicative of a frequency of oscillation of the oscillatory signal, which is the resonant frequency of the resonant tank circuit as affected by the material;
• generating a control signal for controlling an amplitude of the electrical signal so that the oscillatory signal tends toward a constant amplitude;
• processing the frequency signal and an additional signal that is functionally related to the control signal to determine whether the material has a resistance and a reactance characteristic of human flesh;
• and
• when the processing of the frequency signal and the additional signal indicates that the material has the resistance and the reactance characteristic of human flesh, producing an output signal that causes the tool to become disabled from discharging the fastening device.