US Patent 8469067 Detection systems for power equipment

Methods to detect when a human body contacts a predetermined portion of a machine are disclosed. The methods distinguish contact with a person from contact with other materials. The methods are particularly applicable in woodworking equipment such as table saws to distinguish contact between a person and the blade of the saw from contact between the blade and wet or green wood. The methods and woodworking equipment may include predictive blade stop algorithms that prevent unnecessary activations of a safety brake during coast down of a blade and continued protection in the event a main power switch is turned off.