GUARD DETECTION SYSTEM FOR A POWER TOOL

摘要

A power table saw has a saw blade driven by a drive motor with power selectively supplied to the drive motor by actuation of a mains switch. A riving knife is provided that can be selectively positioned in an extended position and a retracted position relative to the blade. A blade guard is removably mounted to the riving knife in a position above the blade. A sensible element on the riving knife can be detected by a first sensor when the riving knife is retracted, the first sensor having a non-null state when the sensible element is adjacent the first sensor and a null state otherwise. A second sensor is configured to detect the presence of the blade guard and has a null state when the blade guard is detected and a non-null state otherwise. A controller is operable to determine the states of the first and second sensors and to disengage power to the drive motor when the mains switch is actuated when the states of the first and second sensors are different.