Patent ID: 7827889

Claim:
A table saw comprising: a frame structure with a generally flat work surface; a blade mounted on an arbor supported by an arm which pivotably coupled to the frame structure such that a portion of the blade extending above the work surface; a drive motor with an output shaft mounted to the frame structure for powering the blade; an actuation mechanism located beneath the work surface and configured to move the blade downwardly below the work surface in a response to an activation signal, the actuation mechanism includes a rod that engages the support arm on one end and is axially driven from a cylinder into the support arm, thereby pivoting the support arm and moving the blade below the work surface; a transmitter capacitively coupled to the blade and operable to transmit an electrical signal to the blade; a receiver capacitively coupled to the blade and operable to receive said electrical signal transmitted to the blade; and a controller connected to said receiver, said controller operable to detect a variation in said electrical signal and send an activation signal to the actuation mechanism when said variation in said electrical signal exceeds said threshold value, where said detection circuit adjusts said threshold value based on an electrical load associated with the operation of the active portion of the power tool.