Safety systems for power equipment

Abstract

A saw with a safety system is disclosed. The safety system includes a detection system adapted to detect contact between a person and a blade while the blade is moving. The safety system further includes a brake system adapted to engage the blade and to stop the blade when the detection system detects contact between the person and the blade.

1 . A saw comprising: 
 a blade configured to move to cut a work piece, where the blade includes at least one cutting edge;    a motor adapted to move the blade;    a detection system adapted to detect contact between a person and the blade while the blade is moving; and    a brake system adapted to engage the cutting edge of the blade and to stop the blade when the detection system detects contact between the person and the blade.    
     
     
         2 . The saw of  claim 1 , further comprising a frame supporting the blade, and where the blade is electrically isolated from the frame.  
     
     
         3 . The saw of  claim 2  where the detection system is adapted to capacitively impart an electric signal on the blade and to detect the occurrence of a determined change in the signal.  
     
     
         4 . The saw of  claim 1 , where the brake system includes a brake pawl biased to engage the blade.  
     
     
         5 . The saw of  claim 4 , where the brake system includes a spring configured to move the brake pawl into the blade.  
     
     
         6 . The saw of  claim 5 , where the brake system includes a release mechanism adapted to selectively restrain the brake pawl from engaging the blade until the detection system detects contact between the person and the blade.  
     
     
         7 . The saw of  claim 6 , where the release mechanism includes a fuse wire that is melted upon detection of contact between the person and the blade.  
     
     
         8 . The saw of  claim 1 , where at least a portion of the brake system is housed in a replaceable cartridge.  
     
     
         9 . The saw of  claim 1 , where the detection system is capacitively coupled to the blade.  
     
     
         10 . The saw of  claim 9 , where the capacitive coupling between the detection system and the blade includes a drive electrode and a sense electrode.  
     
     
         11 . The saw of  claim 1 , further including a control system adapted to monitor the detection system and control actuation of the brake system.  
     
     
         12 . The saw of  claim 11 , where the control system is adapted to shut off the motor when contact between a person and the blade is detected.  
     
     
         13 . The saw of  claim 11 , where the control system is adapted to test at least part of the brake system to verify that at least part of the brake system is operational.  
     
     
         14 . The saw of  claim 1 , where the machine is a table saw.  
     
     
         15 . The saw of  claim 1 , where the machine is a miter saw.  
     
     
         16 . The saw of  claim 1 , where the machine is a radial arm saw.  
     
     
         17 . The saw of  claim 1 , where the machine is a circular saw.  
     
     
         18 . The saw of  claim 1 , where the machine is a band saw.  
     
     
         19 . A saw comprising: 
 an electrically conductive cutter;    detection means for detecting contact between a person and the cutter, where the detection system is adapted to capacitively impart an electric signal on the cutter, and to detect the occurrence of a determined change in the electric signal on the cutter; and    a reaction system associated with the detection means and the cutter, where the reaction system is adapted to cause a predetermined action to take place relative to the cutter upon detection of contact between the person and the cutter by the detection means.    
     
     
         20 . A saw comprising: 
 a blade configured to move to cut a work piece, where the blade includes at least one cutting edge;    a motor adapted to move the blade;    detection means for detecting contact between a person and the blade; and    brake means for stopping the blade when the detection means detects contact between the person and the blade.