Apparatus and method for detecting dangerous conditions in power equipment
First Claim
Patent Images
1. A woodworking machine, comprising:
- a motor;
an electrically isolated, rotatable arbor configured to be driven by the motor, where the arbor has an outer surface;
a circular blade coupled to the arbor;
an excitation system adapted to generate an electrical signal; and
a capacitive coupling adapted to capacitively couple the excitation system to the arbor to transfer at least a portion of the electrical signal to the blade, where the capacitive coupling includes two spaced-apart conductors, and where at least a portion of the outer surface of the arbor is one of the conductors.
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Abstract
Woodworking machines are disclosed having electrically conductive cutting tools adapted to cut workpieces. The machines include a contact detection system capacitively coupled to the cutting tool, and adapted to detect contact between a person and the cutting tool. The machines also include a reaction system configured to cause one or more predetermined actions to take place upon detection of contact between a person and the cutting tool by the contact detection system.
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Citations
19 Claims
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1. A woodworking machine, comprising:
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a motor; an electrically isolated, rotatable arbor configured to be driven by the motor, where the arbor has an outer surface; a circular blade coupled to the arbor; an excitation system adapted to generate an electrical signal; and a capacitive coupling adapted to capacitively couple the excitation system to the arbor to transfer at least a portion of the electrical signal to the blade, where the capacitive coupling includes two spaced-apart conductors, and where at least a portion of the outer surface of the arbor is one of the conductors.
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2. A woodworking machine comprising:
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an electrically conductive cutting tool mounted on a rotatable, electrically conductive shaft; a contact detection system configured to detect contact between a person and the cutting tool, where the contact detection system includes a capacitive coupling adapted to impart an electrical signal onto the cutting tool; and a reaction system configured to cause one or more predetermined actions to take place upon detection of contact between a person and the cutting tool by the contact detection system; where the capacitive coupling comprises at least a portion of the shaft as one conductive plate, and a second conductive plate adjacent to and spaced apart from the shaft so that there is a gap between the shaft and the second conductive plate, and a dielectric in the gap between the shaft and second conductive plate. - View Dependent Claims (3, 4, 5, 6, 7, 8, 14, 15)
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9. A woodworking machine comprising:
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a frame; a conductive cutting tool supported by and electrically insulated from the frame; a motor supported by the frame and adapted to drive the cutting tool; a contact detection system adapted to detect contact between a person and the cutting tool, wherein the contact detection system includes a first electrode capacitively coupled to the cutting tool to impart a signal to the cutting tool and a second electrode capacitively coupled to the cutting tool to monitor the signal imparted to the cutting tool; and a reaction system adapted to stop movement of the cutting tool upon detection of contact between a person and the cutting tool by the contact detection system. - View Dependent Claims (10, 11, 12)
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13. A woodworking machine, comprising:
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an electrically conductive cutting tool; a motor configured to drive the cutting tool; a contact detection system configured to detect contact between a person and the cutting tool; a capacitive coupling between the contact detection system and the cutting tool, where the capacitive coupling comprises at least a portion of the cutting tool as one conductive plate, and a second conductive plate adjacent to and spaced apart from the cutting tool so that there is a gap between the cutting tool and the second conductive plate; and a brake mechanism configured to engage and stop the cutting tool if contact between the person and the cutting tool is detected by the contact detection system; where the contact detection system is configured to impart an electrical signal onto the cutting tool through the capacitive coupling, and to detect contact between a person and the cutting tool based on changes in the electrical signal imparted to the cutting tool. - View Dependent Claims (16, 17, 18, 19)
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Specification