US 4,588,978 AGranted

Remote switch-sensing system

AssigneeTransensory Devices, Inc.

InventorHenry V. Allen

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Abstract

A system for monitoring vehicle tire pressure, or the like. The system includes a transmitter and a receiver mounted on the vehicle body, and magnetically coupled inductor and enhancer circuits carried on the vehicle wheel. The inductor circuit contains an open/closed condition switch which is responsive to tire pressure. The transmitter signal, acting through the inductor and enhancer circuits, produces a response voltage in the receiver which varies at a selected transmitter frequency according to the condition of the switch. In one embodiment of the invention, the inductor and enhancer circuits are tuned to enhance the response voltage in the receiver, at a selected transmitter frequency and at one inductor circuit switch condition. In a second embodiment, the inductor and enhancer circuits are tuned to produce receiver signals which have one signal-to-noise ratio peak at one transmitter frequency and with the pressure switch in one condition, and a second signal-to-noise ratio peak, at a second transmitter frequency and with the switch in its other condition.

Claims22

Dependent claims

A system for monitoring an open/closed condition switch carried on one of a pair of remote members, said system comprising

a transmitter mounted on the other remote member, including a transmitter coil which is positioned adjacent the one remote member, and means for coupling an alternating current to said coil, such that a selected-frequency electromagnetic field is generated thereby,
an inductor circuit carried on the one remote member, including an inductor coil operatively positioned adjacent the transmitter coil during operation of the system, and a switch element including such open/closed condition switch and circuit components operatively connecting the switch to the inductor-circuit coil to vary, according to the condition of the switch, the characteristics of a signal induced in the circuit by magnetic coupling between the transmitter and circuit coils, when the transmitter is generating such selected-frequency field,
a receiver mounted on the other remote member, including a coil positioned for magnetic coupling to the inductor-circuit coil during operation of the system, and a monitoring circuit for detecting the signal response voltage in the inductor circuit according to a signal produced in the receiver coil by inductive coupling with the inductor circuit coil, and
an enhancer circuit carried on the one remote member, including an inductor coil magnetically coupled to the inductor-circuit coil, and circuit means for producing resonance characteristics in the enhancer circuit which act to increase the signal voltage produced in the receiver circuit coil at a selected signal frequency, over that producible in the receiver circuit coil in the absence of the enhancer circuit.

1 more element

A system for monitoring the pressure in the tire of a vehicle wheel comprising

a transmitter mounted on the vehicle, including a transmitter coil positioned adjacent such vehicle wheel, and an alternating-current signal generator for generating selected-frequency alternating current electromagnetic fields in said coil,
an inductor circuit carried on the wheel for rotation therewith, including an inductor coil operatively positioned adjacent the transmitter coil, and a switch element including a pressure-responsive, open/closed condition switch operatively connected to the inductor-circuit coil to vary the Q characteristics of the circuit according to the switch condition,
a receiver mounted on the vehicle, including a coil positioned for magnetic coupling to the inductor circuit coil, and a monitoring circuit for detecting signal voltage in the inductor circuit according to a signal produced in the receiver coil by inductive coupling with the inductor circuit coil, and
an enhancer circuit carried on the wheel for rotation therewith, including an inductor coil which is magnetically coupled to the inductor circuit coil, and circuit means for producing resonance characteristics in the enhancer circuit which produce, through coupling to the inductor circuit coil, receiver signals which have a first signal-to-noise ratio peak, at one transmitter field frequency, with the switch element in its closed condition, and a second signal-to-noise ratio peak at a second transmitter field frequency, with the switch element in its open condition.

1 more element

Dependencies are inferred from the claim text.