Patent ID: 8336432

Claim:
A machine tool safety system adapted for electrical connection to an electric-motor-driven machine tool, comprising: a substantially transparent safety guard ( 16 ), shaped to surround at least one dangerous part of a machine tool, and fixed in place to prevent a portion of a human operator's body from contacting said dangerous part; at least one electrical element ( 14 ), forming part of said safety guard, and coupled to an electronic flesh-sensing response circuit ( 19 ) which detects any capacitance change of at least 10 picofarads resulting when an operator contacts said electrical element ( 14 ), and generates a corresponding output signal; an electrical control circuit connected to the flesh-sensing circuit ( 19 ) in such a way as to sense bodily contact; and an electrical control circuit which, upon receiving said output signal from the flesh-sensing circuit ( 19 ), generates a current burst, on a winding of a motor of said electric-motor-driven machine tool, having a duration of at least 200 milliseconds to brake motion of a rotor of said motor, to a negligible speed, quickly enough to avoid injury to a body part of said operator.