Transducer and interrogator device

Patent 5701121 Issued on December 23, 1997. Estimated Expiration Date:

December 23, 2014. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

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Inventor

Murdoch, Graham Alexander M.

Assignee

Application

No. 356782 filed on 12/12/1994

US Classes:

340/10.34, Power up340/825.72, Wireless link340/870.31, Inductive transmitter455/41.1Near field (i.e., inductive or capacitive coupling)

Examiners

Primary: Hofsass, Jeffery
Assistant: Hill, Andrew

Attorney, Agent or Firm

Learman & McCulloch

Foreign Patent References

2163324 GB. 02/13/1986
2191029 GB. 12/13/1987

International Class

G08C 019/00

Foreign Application Priority Data

1988-04-11 AU

Abstract

A transducer and interrogator device is disclosed in which the interrogator provides power and information to the transducer via a magnetic field. The transducer is a passive actuator device that includes an inductive pickup coil that, when subjected to the interrogator's magnetic field, powers the passive actuator and an external electrical device. The magnetic field produced by the interrogator can be modulated in such a manner as to provide identification, commands, or other information to the passive actuator without substantially reducing the power transferred to the passive actuator. Modulation can be by amplitude, phase, frequency, pulse width, or pulse position. An antiphase magnetic field can also be generated to cancel far field radiation. The passive actuator can include a logic circuit to demodulate any received data from the interrogator via the magnetic field, which data can be used to control the operation of the external device. The passive actuator can also include a circuit for transmitting information back to the interrogator using the power extracted from the interrogator's magnetic field. Transmission can be either by a modulated electromagnetic signal generated by an oscillator internal to the passive actuator or by coupled impedance signalling using the passive actuator's pickup coil.