Motion detecting system for use in a safety system for power equipment

(54) MOTION DETECTING SYSTEM FOR USE IN A SAFETY SYSTEM FOR POWER EQUIPMENT

(76) Inventor: Stephen F. Gass, Wilsonville, OR (US)

Correspondence Address:
SD3, LLC

25977 S.W. Canyon Creek Road, Suite G
WILSONVILLE, OR 97070 (US)

(21) Appl. No.: 11/506,260

(22) Filed: Aug. 18, 2006

Related U.S. Application Data

(63) Continuation of application No. 10/923,282, filed on Aug. 20, 2004.

Continuation of application No. 09/929,234, filed on
Aug. 13, 2001.

(60) Provisional application No. 60/496,568, filed on Aug. 20, 2003. Provisional application No. 60/225,056, filed on Aug. 14, 2000. Provisional application No. 60/225,057, filed on Aug. 14, 2000. Provisional application No. 60/225,058, filed on Aug. 14, 2000. Provisional application No. 60/225,059, filed on Aug. 14, 2000. Provisional application No. 60/225,089, filed onAug. 14, 2000. Provisional application No. 60/225, 094, filed on Aug. 14, 2000. Provisional application No. 60/225,169, filed on Aug. 14, 2000. Provisional application No. 60/225,170, filed on Aug. 14, 2000.

A woodworking machine including a detection system adapted to detect a dangerous condition between a person and a working portion of the machine is disclosed. The machine includes a reaction system associated with the detection system to cause a predetermined action to take place relative to the working portion upon detection of the dangerous condition. A motion detection system is adapted to detect motion of the working portion and to disable the reaction system when the working portion is not moving. The motion detection system may sense whether motion in a machine has stopped by monitoring the back emf produced on the motor leads as the motor coasts to a stop. The woodworking machine may take the form of a saw, the working portion may be a blade adapted to cut when spinning, and the dangerous condition may be a person contacting the blade.