Safety detection and protection system for power tools
First Claim
Patent Images
1. A table saw comprising:
- a frame structure with a generally flat work surface;
a rotatable circular blade mounted on an arbor and being adapted to have at least a portion of said blade extending above the flat work surface in position to cut a work piece;
a drive motor with an output shaft mounted to the frame structure for powering the saw blade;
a sensing mechanism for generating at least a first actuation signal responsive to predetermined sensed characteristics relating to the existence and/or movement of a person in close proximity thereto; and
a retracting mechanism located beneath said work surface for rapidly moving said blade downwardly below the work surface responsive to said first actuation signal being received.
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Abstract
A detection system for detecting a dangerous condition for an operator using a power tool of the type which has an exposed blade relative to a work surface and a protection system for minimizing, if not eliminating the possibility of a user being injured by contacting the blade. In one preferred embodiment of the present invention, a proximity detection system is capable of detecting the presence of a user near the blade of a table saw and a protection system that can either retract the blade below the work surface of the table saw or terminate the drive torque to the blade which can result in rapid stopping of the saw blade by a work piece that is being cut.
221 Citations
45 Claims
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1. A table saw comprising:
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a frame structure with a generally flat work surface;
a rotatable circular blade mounted on an arbor and being adapted to have at least a portion of said blade extending above the flat work surface in position to cut a work piece;
a drive motor with an output shaft mounted to the frame structure for powering the saw blade;
a sensing mechanism for generating at least a first actuation signal responsive to predetermined sensed characteristics relating to the existence and/or movement of a person in close proximity thereto; and
a retracting mechanism located beneath said work surface for rapidly moving said blade downwardly below the work surface responsive to said first actuation signal being received. - View Dependent Claims (2, 3, 4)
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5. A table saw comprising:
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a frame structure with a generally flat work surface;
a rotatable circular blade mounted on an arbor and being adapted to have at least a portion of said blade extending above the flat work surface in position to cut a work piece;
a drive motor with an output shaft mounted to the frame structure for powering the saw blade;
a sensing mechanism for generating at least a first actuation signal responsive to predetermined sensed characteristics relating to the existence and/or movement of a person in close proximity thereto; and
a retracting mechanism located beneath said work surface for rapidly moving said blade downwardly below the work surface responsive to said first actuation signal being received, wherein said retracting mechanism further comprises;
an arm structure that has a first pulley operatively coupled to said arbor, a second pulley operatively coupled to said output shaft of said drive motor and a flexible belt coupling said first and second pulleys, said arm structure pivoting about an axis concentric with said output shaft so that the tension in said belt is relatively constant regardless of the position of the blade relative to said work surface; and
an actuator connected to said frame structure and said arm structure for rapidly moving said arm structure to cause said blade to be moved below said work surface responsive to receiving said first actuation signal from said sensing mechanism. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A table saw comprising:
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a frame structure with a generally flat work surface;
a rotatable circular blade mounted on an arbor and being adapted to have at least a portion of said blade extending above the flat work surface in position to cut a work piece;
a drive motor with an output shaft mounted to the frame structure for powering the saw blade;
a sensing mechanism for generating at least a first actuation signal responsive to predetermined sensed characteristics relating to the existence and/or movement of a person in close proximity thereto;
a retracting mechanism located beneath said work surface for rapidly moving the blade downwardly below the work surface responsive to said first actuation signal being received, wherein said retracting mechanism moves said blade beneath said work surface within less than approximately 7 milliseconds after said first actuation signal is received by said retracting mechanism.
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12. A table saw comprising:
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a frame structure with a generally flat work surface;
a rotatable circular blade mounted on an arbor and being adapted to have at least a portion of said blade extending above the flat work surface in position to cut a work piece, said circular blade being electrically isolated from said arbor, a drive motor output shaft and said frame structure work surface, so that an excitation field can be applied to said blade;
a drive motor with an output shaft mounted to the frame structure for powering said blade;
a sensing mechanism for generating at least a first actuation signal responsive to predetermined sensed characteristics relating to the existence and/or movement of a person in close proximity thereto;
a retracting mechanism located beneath said work surface for rapidly moving the blade downwardly below the work surface responsive to said first actuation signal being received, wherein said sensing mechanism comprises;
said work surface defining a ground plane and having a slot opening through which said blade can extend;
at least one electrically conductive deflection plate electrically isolated from but attached to said work surface for shaping an electric field that emanates from said blade when an excitation field is applied thereto;
circuitry for selectively generating and applying excitation signals to each of said deflection plates and to said blade to thereby define at least one sensing volume near said blade above said work surface;
circuitry for sensing the dielectric constant of said sensing volume and generating sensed signals that are indicative of the sensed dielectric constant;
a processor for receiving said generated signals and for producing said first actuation signal when predetermined sensed characteristics indicate that a person is in a highly dangerous position relative to said blade. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A system for sensing an object in proximity to a surface, said system comprising:
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said surface defining an electrical ground;
at least one electrically conductive deflection plate electrically isolated from but operatively attached to said surface;
at least one electrically conductive sensor electrically isolated from but operatively associated with said deflection plate;
said at least one deflection plate shaping an electric field that emanates from said at least one sensor when an excitation field is applied thereto;
circuitry for selectively generating and applying excitation signals to each of said deflection plates and to said sensor to thereby define at least one sensing volume near said sensor away from said surface;
circuitry for sensing the dielectric constant of said sensing volume and generating sensed signals that are indicative of the sensed dielectric characteristic;
a digital processor for receiving said generated signals and for determining the presence of the object from an analysis of a plurality of said generated sensed signals. - View Dependent Claims (39, 40, 41, 42, 43)
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44. A system for sensing a human in proximity to a moving element of a structure which is in proximity to a sensor operatively associated with the structure, said system comprising:
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at least a portion of said structure defining an electrical ground;
at least one electrically conductive deflection member electrically isolated from but operatively attached to said portion of said structure;
at least one electrically conductive sensor electrically isolated from but operatively associated with said deflection member;
said at least one deflection member shaping an electric field that emanates from said at least one sensor when an excitation field is applied thereto;
circuitry for selectively generating and applying excitation signals to each of said deflection member and to said sensor to thereby define at least one sensing volume near said moving element;
circuitry for sensing the dielectric characteristics of said sensing volume and generating sensed signals that are indicative of the sensed dielectric characteristics;
a digital processor for receiving said generated signals and for determining the presence of the human in proximity to said moving element from an analysis of a plurality of said generated sensed signals. - View Dependent Claims (45)
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Specification