Abstract An automatic safety brake for rotary blade equipment in which a capacitance proximity sensor utilizes the spinning blade as an antenna so that when any portion of the body of the user approaches the blade to closely a cam brake will be instantaneously actuated to stop the rotation of the blade before the body of the user comes in contact with the cutting edge of the blade. In one form of the invention cam members are applied to opposite side faces of the blade to serve as a brake for the instanteous stopping of the rotation of the blade. In another form of the invention a rubber wedge is driven into the cutting edge of the blade so as to instantaneously stop the rotation of the blade. In both forms of the invention the sensitivity of the sensor may be adjusted to suit the capacitance effect of the individual user of the equipment.
A power tool comprising a frame, a rotating cutting blade mounted in said frame, a brake mounted in said frame for movement into blade contacting position, a solenoid mounted in said frame and connected to said brake for moving said brake into contact with said blade, a capacitance proximity sensor mounted on said frame for detecting the approach of a portion of a human body to said blade, and means actuated by said sensor for energizing said solenoid to instanteously stop said blade when a portion of the human body closely approaches said blade.
Claim 2
Dependent Claim
94 words
A power tool comprising a frame, a rotating cutting blade mounted in said frame, a brake mounted in said frame for movement into blade contacting position, a solenoid mounted in said frame and connected to said brake for moving said brake into contact with said blade, a capacitance proximity sensor mounted on said frame for detecting the approach of a portion of a human body to said blade, and means actuated by said sensor for energizing said solenoid to instanteously stop said blade when a portion of the human body closely approaches said blade.
Claim 3
Dependent Claim
30 words
A device as claimed in claim 1 including means for adjusting the relative senitivity of said sensor to tune said sensor to the capacitances of the body of the user.
Claim 4
Dependent Claim
27 words
A device as claimed in claim 1 wherein an audible signal is actuated by the means for actuating said solenoid prior to the actuation of said solenoid.
Claim 5
Dependent Claim
30 words
A device as claimed in claim 1 wherein said brake is mounted for rotation and includes a cam surface for binding engagment with the side face of said saw blade.
Claim 6
Dependent Claim
28 words
A device as claimed in claim 1 wherein said brake is mounted for sliding movement with respect to said blade and engages the cutting edge of said blade.