Capacitively coupled machine tool safety having a self-test network
First Claim
1. A machine tool safety system comprising:
- an electric field generator adapted to be carried on a portion of the person of a machine tool operator for generating an electric field;
a capacitive receptor antenna mountable in a predetermined location with respect to a machine tool and cooperable with the electric field generator to form a capacitively coupled transmission arrangement operative to induce, by the action of the electric field through the capacitive coupling, a monotonically increasing electrical signal the magnitude of which is functionally related to the distance between the electric field generator and the capacitive receptor antenna;
a signal processor connected to the capacitive receptor antenna and responsive to the signal induced in the capacitive receptor antenna by the electric field to generate an indication when the magnitude of the induced electrical signal exceeds a predetermined threshold, the indication being able to be used to permit safe operation of a machine tool;
a self-test radiating antenna disposed in proximity to the capacitive receptor antenna; and
a self-test network electrically connected to the self-test radiating antenna for generating an excitation signal operative to induce in the capacitive receptor antenna a test signal having a magnitude greater than the threshold.
1 Assignment
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Accused Products
Abstract
A machine tool safety system includes an electric field generator capacitively coupled to a receptor antenna. A self-test network includes a self-test radiating antenna and a circuit arrangement operative to apply a test signal to the self-test antenna. The test signal may be of sufficient strength to induce in the receptor antenna a first excitation signal having a magnitude greater than a first predetermined threshold to verify that the safety system is operative to detect the entry of the field generator carried on an operator'"'"'s person into a hazard zone proximal to the machine tool. The test signal may be of sufficient strength to induce a second excitation signal greater than a second threshold to verify that the safety system is operative to detect the entry of the field generator into an arming zone spaced from the hazard zone.
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Citations
15 Claims
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1. A machine tool safety system comprising:
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an electric field generator adapted to be carried on a portion of the person of a machine tool operator for generating an electric field; a capacitive receptor antenna mountable in a predetermined location with respect to a machine tool and cooperable with the electric field generator to form a capacitively coupled transmission arrangement operative to induce, by the action of the electric field through the capacitive coupling, a monotonically increasing electrical signal the magnitude of which is functionally related to the distance between the electric field generator and the capacitive receptor antenna; a signal processor connected to the capacitive receptor antenna and responsive to the signal induced in the capacitive receptor antenna by the electric field to generate an indication when the magnitude of the induced electrical signal exceeds a predetermined threshold, the indication being able to be used to permit safe operation of a machine tool; a self-test radiating antenna disposed in proximity to the capacitive receptor antenna; and a self-test network electrically connected to the self-test radiating antenna for generating an excitation signal operative to induce in the capacitive receptor antenna a test signal having a magnitude greater than the threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification