Pressure based wireless sensor and applications thereof

Patent metadata

Field	Value
Publication number	US-9789738-B2
Application number	US-201615348365-A
Country	US
Kind code	B2
Filing date	Nov 10, 2016
Priority date	Sep 29, 2014
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A wireless sensor includes an antenna, a tuning circuit, a pressure sensing circuit, a processing module, and a transmitter. Collectively, the pressure sensing circuit, the antenna, and the tuning circuit have one or more radio frequency (RF) characteristics and the pressure sensing circuit causes the RF characteristic(s) to vary with varying sensed pressures. The processing module detects a variance of the RF characteristic(s) from a desired value. In response to the detecting of the variance, the processing module adjusts the tuning circuit to substantially re-establish the desired value of the RF characteristic(s). The processing module generates a message regarding the adjusting of the tuning circuit, wherein a level of the adjusting is representative of a variance of pressure sensed by the pressure sensing circuit. The transmitter transmits the message.

First claim

What is claimed is:

1. A wireless sensor comprises:
an antenna;
a tuning circuit operably coupled to the antenna;
a pressure sensing circuit operably coupled at least one of the antenna and the tuning circuit, wherein the antenna, the tuning circuit, and the pressure sensing circuit collectively have one or more radio frequency (RF) characteristics and wherein the pressure sensing circuit causes the one or more RF characteristics to vary with varying sensed pressures;
a processing module operable to:
detect a variance of the one or more RF characteristics from a desired value of the one or more RF characteristics;
in response to the detecting of the variance, adjust the tuning circuit to substantially re-establish the desired value of the one or more RF characteristics; and
generate a message regarding the adjusting of the tuning circuit, wherein a level of the adjusting of the tuning circuit is representative of a variance of pressure sensed by the pressure sensing circuit; and

a transmitter operably coupled to transmit the message.

2. The wireless sensor of claim 1 , wherein the pressure sensing circuit comprises:
a variable capacitance circuit that includes a first plate, a second plate, and a diaphragm, wherein, as a result of pressure variations on the diaphragm, causes a change in capacitance of the variable capacitance circuit.

3. The wireless sensor of claim 1 , wherein the pressure sensing circuit comprises:
a variable capacitance circuit that includes a first plate, a second plate, and a diaphragm puck, wherein, as a result of pressure variations on the diaphragm puck, causes a change in capacitance of the variable capacitance circuit.

4. The wireless sensor of claim 1 , wherein the pressure sensing circuit comprises:
a variable inductance circuit that includes a tuning loop and a diaphragm that, as a result of pressure variations, causes an inductance change of the tuning loop.

5. The wireless sensor of claim 1 , wherein the pressure sensing circuit comprises:
a variable inductance circuit that includes a tuning loop and a diaphragm puck that, as a result of pressure variations, causes an inductance change of the tuning loop.

6. The wireless sensor of claim 1 , wherein an RF characteristic of the one or more RF characteristics comprises:
an impedance at a frequency;
a resonant frequency;
a quality factor; and
a gain.

7. The wireless sensor of claim 1 , wherein the processing module is further operable to:
in response to a calibration request at a known pressure, adjust the tuning circuit to establish the desired value of the one or more RF characteristics; and
record a level of the adjusting of the tuning circuit to represent a pressure calibration of the wireless sensor.

8. The wireless sensor of claim 1 further comprises:
a second antenna; and
a power harvesting circuit operably coupled to the second antenna, wherein, when the second antenna receives an RF signal, the power harvesting circuit converts the RF signal into a power supply voltage.

9. The wireless sensor of claim 1 further comprises:
a temperature sensor operably coupled to the processing module, wherein the temperature sensor senses a temperature of an environment proximal to the wireless sensor, and wherein the processing module includes a sensed temperature within the message.

10. A passive wireless tire pressure sensor comprises:
an antenna;
a tuning circuit operably coupled to the antenna;
a pressure sensing circuit operably coupled to at least one of the antenna and the tuning circuit, wherein the antenna, the tuning circuit, and the pressure sensing circuit collectively have one or more radio frequency (RF) characteristics and wherein the pressure sensing circuit causes the one or more RF characteristics to vary with varying sensed pressures;
a second antenna;
a power harvesting circuit operably coupled to the second antenna, wherein, when the second antenna receives an RF signal, the power harvesting circuit converts the RF signal into a power supply voltage;
a processing module powered via the power supply voltage, wherein the processing module is operable to:
detect a variance of the one or more RF characteristics from a desired value of the one or more RF characteristics;
in response to the detecting of the variance, adjust the tuning circuit to substantially re-establish the desired value of the one or more RF characteristics; and
generate a message regarding the adjusting of the tuning circuit, wherein a level of the adjusting of the tuning circuit is representative of a variance of pressure sensed by the pressure sensing circuit; and

a transmitter powered by the power supply voltage, wherein the transmitter transmits the message.

11. The passive wireless tire pressure sensor of claim 10 , wherein the pressure sensing circuit comprises:
a variable capacitance circuit that includes a first plate, a second plate, and a diaphragm, wherein, as a result of pressure variations on the diaphragm, causes a change in capacitance of the variable capacitance circuit.

12. The passive wireless tire pressure sensor of claim 10 , wherein the pressure sensing circuit comprises:
a variable capacitance circuit that includes a first plate, a second plate, and a diaphragm puck, wherein, as a result of pressure variations on the diaphragm puck, causes a change in capacitance of the variable capacitance circuit.

13. The passive wireless tire pressure sensor of claim 10 , wherein the pressure sensing circuit comprises:
a variable inductance circuit that includes a tuning loop and a diaphragm that, as a result of pressure variations, causes an inductance change of the tuning loop.

14. The passive wireless tire pressure sensor of claim 10 , wherein the pressure sensing circuit comprises:
a variable inductance circuit that includes a tuning loop and a diaphragm puck that, as a result of pressure variations, causes an inductance change of the tuning loop.

15. The passive wireless tire pressure sensor of claim 10 , wherein the processing module is further operable to:
in response to a calibration request at a known pressure, adjust the tuning circuit to establish the desired value of the one or more RF characteristics; and
record a level of the adjusting of the tuning circuit to represent a pressure calibration of the wireless tire pressure sensor.

16. The passive wireless tire pressure sensor of claim 10 , wherein the power harvesting circuit is further operable to:
converts the RF signal into a first power supply voltage for powering the processing module; and
converts the RF signal into a second power supply voltage.

17. The passive wireless tire pressure sensor of claim 10 further comprises:
a temperature sensor operably coupled to the processing module, wherein the temperature sensor senses a temperature of an environment proximal to the wireless tire pressure sensor, and wherein the processing module includes a sensed temperature within the message.

18. The passive wireless tire pressure sensor of claim 10 further comprises:
the second antenna being physically mounted on a stem of a tire such that at least a portion of the second antenna is on an outside of the tire; and
the antenna and the pressure circuit are mounted within the tire.

Assignees

• Rfmicron Inc

Inventors

• Rokhsaz Shahriar
• Young Brian David

Classifications

• H04L67/04

  specially adapted for terminals or networks with limited capabilities; specially adapted for terminal portability · CPC title

• H04W84/18

  Self-organising networks, e.g. ad-hoc networks or sensor networks · CPC title

• H04L67/12

  specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks · CPC title

• G06K7/10297

  arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092 (cryptographic protocols H04L9/00; network security protocols H04L63/00; real-time communication protocols in data switching networks H04L65/00; network protocols for data switching network services H04L67/00) · CPC title

• H04L67/00

  Network arrangements or protocols for supporting network services or applications (user-to-user messaging H04L51/00; network arrangements, protocols or services for supporting real-time applications in data packet communications networks H04L65/00) · CPC title