Detection system for power equipment
First Claim
1. A woodworking machine adapted to process a workpiece, where the woodworking machine has a location potentially dangerous to a person, the machine comprising:
- an electrically conductive sensor positioned at the potentially dangerous location in the machine; and
a contact detection system operably connected to the sensor to receive a signal therefrom, where the signal changes upon contact between the sensor and a person and upon contact between the sensor and the workpiece, and where the contact detection system is configured to differentiate contact with the person from contact with the workpiece based on the rate at which the signal changes.
6 Assignments
0 Petitions
Accused Products
Abstract
Woodworking machines including conductive cutters adapted to cut workpieces, and motors adapted to drive the cutters are disclosed. The machines also include a contact detection system adapted to detect contact between a person and the cutter, and to distinguish contact between the person and the cutter from contact between the workpiece and the cutter. The machines further include a reaction system adapted to cause a predetermined action to take place upon detection of contact between the person and the cutter by the contact detection system.
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Citations
17 Claims
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1. A woodworking machine adapted to process a workpiece, where the woodworking machine has a location potentially dangerous to a person, the machine comprising:
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an electrically conductive sensor positioned at the potentially dangerous location in the machine; and
a contact detection system operably connected to the sensor to receive a signal therefrom, where the signal changes upon contact between the sensor and a person and upon contact between the sensor and the workpiece, and where the contact detection system is configured to differentiate contact with the person from contact with the workpiece based on the rate at which the signal changes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A woodworking machine comprising:
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a cutter adapted to cut a workpiece; and
a contact detection system adapted to detect contact between a person and the cutter, the contact detection system including;
an excitation system adapted to supply an electrical signal having a first amplitude and period, the electrical signal being coupled to the cutter to induce a corresponding electrical signal of a second amplitude on the cutter, and a sensing system adapted to sense the second electrical signal induced onto the cutter, where the sensing system is adapted to detect contact between a person and the cutter based on a change in the sensed second electrical signal over a detection period, where the detection period is between 5 and 150 microseconds and at least twice the period of the first electrical signal. - View Dependent Claims (10, 11, 12, 13)
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14. A woodworking machine comprising:
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a support structure;
a motor supported by the support structure;
a blade assembly including a blade with cutting teeth, where the blade assembly is supported by the support structure and moveable by the motor, and where the blade assembly is electrically isolated from the support structure;
a contact detection system to detect contact between the blade assembly and a person, where the contact detection system includes;
an electrode adjacent the blade assembly to create a capacitive coupling to the blade assembly, where the blade assembly has an apparent capacitance, and circuitry adapted to detect a pre-selected increase in the apparent capacitance of the blade assembly, where the pre-selected increase in the apparent capacitance of the blade assembly is selected to correspond to the pre-selected increase in the apparent capacitance resulting from conductively coupling a person to the blade assembly so that the pre-selected increase in the apparent capacitance represents contact between the blade assembly and the person;
a brake mechanism adapted to stop the blade by moving into contact with the teeth of the blade upon detection of the pre-selected increase in the apparent capacitance of the blade assembly. - View Dependent Claims (15)
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16. For use in connection with a woodworking machine having a motor-driven cutting tool, a method of detecting contact between a person and the cutting tool, the method comprising:
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imparting an electrical signal onto the cutting tool, where the electrical signal has an alternating voltage amplitude defining plural voltage peaks;
sensing the electrical signal imparted onto the cutting tool; and
detecting contact between a person and the cutting tool by detecting that a predetermined plural number of the voltage peaks of the sensed electrical signal have amplitudes outside a specified range of amplitudes.
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17. A woodworking machine having a cutting tool adapted to cut workpieces, the machine comprising:
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means for driving the cutting tool;
means for detecting contact between a person and the cutting tool;
means for distinguishing contact between a person and the cutting tool from contact between green wood and the cutting tool; and
means for stopping movement of the cutting tool upon detection of contact between the person and the cutting tool.
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Specification