Passive inductive switch
First Claim
1. A system for remotely activating a deployed device, the deployed device having a load and a battery, the system comprising:
- (a) a transmitter, remote from the deployed device, for generating an AC magnetic field; and
(b) a receiver disposed at the deployed device, the receiver including(i) an antenna and a voltage detector coupled to said antenna for sensing the AC magnetic field and generating an output signal in response to the sensed AC magnetic field, wherein said voltage detector only generates said output signal when the sensed AC magnetic field induces a voltage in said antenna and said voltage exceeds a threshold voltage;
(ii) a switch coupled in series with the load and the battery; and
(iii) an integrating delay circuit coupled between the voltage detector and said switch for integrating the output signal,said switch being responsive to said integrating delay circuit to couple the battery to the load, thereby activating the deployed device,and wherein said voltage detector includes at least one semiconductor device, said semiconductor device having a cutoff mode and an active mode, and wherein said semiconductor device operates in said cutoff mode when said induced voltage is below the threshold voltage, and operates in said active mode when said induced voltage is above the threshold voltage.
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Accused Products
Abstract
A passive inductive switch for coupling a battery to a load in a remotely deployed battery-powered electronic device. The switch operates in response to a transmitted magnetic field at a particular frequency. The switch includes an antenna for transforming the magnetic field into an induced voltage and a voltage detector for sensing the induced voltage and triggering a switching element. The switch operates in a standby mode until a sufficient voltage is induced in the antenna which causes the switch to couple the battery to the load. In the standby mode the switch draws a negligible amount of power, which permits the device to be deployed in the field for long periods of time without expending significant battery power.
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Citations
33 Claims
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1. A system for remotely activating a deployed device, the deployed device having a load and a battery, the system comprising:
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(a) a transmitter, remote from the deployed device, for generating an AC magnetic field; and (b) a receiver disposed at the deployed device, the receiver including (i) an antenna and a voltage detector coupled to said antenna for sensing the AC magnetic field and generating an output signal in response to the sensed AC magnetic field, wherein said voltage detector only generates said output signal when the sensed AC magnetic field induces a voltage in said antenna and said voltage exceeds a threshold voltage; (ii) a switch coupled in series with the load and the battery; and (iii) an integrating delay circuit coupled between the voltage detector and said switch for integrating the output signal, said switch being responsive to said integrating delay circuit to couple the battery to the load, thereby activating the deployed device, and wherein said voltage detector includes at least one semiconductor device, said semiconductor device having a cutoff mode and an active mode, and wherein said semiconductor device operates in said cutoff mode when said induced voltage is below the threshold voltage, and operates in said active mode when said induced voltage is above the threshold voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A device for remote deployment, having both an active mode and a standby mode, the device switching from the standby mode to the active mode in response to the sensing of an AC magnetic field transmitted from a remote transmitter, the device comprising:
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(a) a load; (b) a battery; and (c) a receiver including (i) an antenna and a voltage detector coupled to said antenna for sensing the AC magnetic field and for generating an output signal in response to the sensed AC magnetic field, wherein said voltage detector only generates said output signal when the sensed AC magnetic field induces a voltage in said antenna and said voltage exceeds a threshold voltage; (ii) a switch coupled in series with the load and the battery; and (iii) an integrating delay circuit coupled between the voltage detector and said switch for integrating the output signal, said switch being responsive to said integrating delay circuit to couple the battery to the load, thereby activating the deployed device, wherein said voltage detector includes at least one semiconductor device, said semiconductor device having a cutoff mode and an active mode, and wherein said semiconductor device operates in said cutoff mode when said induced voltage is below the threshold voltage, and operates in said active mode when said induced voltage is above the threshold voltage. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A deployable device, comprising a load, a battery, and a passive inductive switch for selectively coupling the load to the battery in response to a received AC magnetic field, the passive inductive switch comprising:
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a tuned antenna a voltage detector connected across the tuned antenna for receiving and rectifying AC electrical signals induced in the tuned antenna by the AC magnetic field, wherein the voltage detector comprises a first semiconductor junction having at least one terminal connected to the battery and operating in cutoff mode unless said electrical signals exceed a threshold voltage whereupon the voltage detector outputs a rectified AC output; an integrating delay circuit connected to the voltage detector for receiving the rectified AC output and for integrating the rectified AC output to provide an integrated voltage signal; and a semiconductor switch connected in series between the battery and the load for selectively coupling the load to the battery, and connected to the integrating delay circuit, whereby the switch comprises a normally-open switch configured to connect the load to the battery in response to the integrated voltage signal, wherein the voltage detector and semiconductor switch draw no bias currents from the battery when in a standby mode, and wherein the passive inductive switch draws only semiconductor leakage currents from the battery when in said standby mode. - View Dependent Claims (29, 30, 31, 32, 33)
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Specification