|Publication number||USH1744 H|
|Application number||US 08/532,944|
|Publication date||Aug 4, 1998|
|Filing date||Sep 21, 1995|
|Priority date||Sep 21, 1995|
|Publication number||08532944, 532944, US H1744 H, US H1744H, US-H-H1744, USH1744 H, USH1744H|
|Inventors||Stanley R. Clayton, Mark R. Roser, Stephen D. Russell, Randy L. Shimabukuro|
|Original Assignee||Clayton; Stanley R., Roser; Mark R., Russell; Stephen D., Shimabukuro; Randy L.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (14), Referenced by (17), Classifications (8), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to a ring oscillator that senses temperature and transmits temperature information to a radio receiver.
Thermometric oscillators are one of many devices used to sense temperature. Other temperature sensing devices include thermocouples, resistance temperature detectors, and junction diodes. Typically these devices are placed in close proximity to the point where the measurement is desired and are connected by wires to other electronic components that process the output of the sensing device. In many applications, however, the wires connecting to the sensing device are inconvenient. In a production line, for example, the sensing device may be moving while the other components preferably remain stationary. In other applications, a temperature sensing point may be difficult to access, such as inside a nuclear reactor or some other harsh environment, where wired connections may be inconvenient.
Another disadvantage is that the temperature range of the sensing device may not extend to the range of interest.
Optical pyrometry is a well known technique for measuring temperature that does not require connecting wires to the point of measurement. Optical pyrometers measure the intensity of electromagnetic radiation from an object to determine temperature. However, the accuracy of the temperature measurement is dependent on the accuracy of the emissivity given for the object. Also, intervening material between the object and the pyrometer may distort the temperature measurement. Furthermore, optical pyrometry is currently limited to elevated temperatures where emissivity is high.
The thermometric ring oscillator of the present invention addresses the problems described above, and may provide further related advantages. The following description of a thermometric ring oscillator does not preclude other embodiments and advantages of the present invention that may exist or become obvious to those skilled in the art.
A temperature measuring device comprises a ring oscillator having a nominal oscillating frequency positioned at a location where temperature is to be measured. The ring oscillator emits electromagnetic radiation to an antenna located at a convenient distance from the ring oscillator. The antenna transforms the electromagnetic radiation into an electrical signal. A receiver receives the electrical signal and measures the frequency of the electrical signal to determine the corresponding temperature. The temperature may then be visually monitored from a display or electronically monitored by other devices.
An advantage of the thermometric ring oscillator is that both temperature sensing and wireless transmission of temperature data are performed with a minimum of parts.
Another advantage is that the thermometric ring oscillator may be incorporated with other electronic devices and circuits for measuring temperature under actual operating conditions.
A further advantage is that the thermometric ring oscillator may be miniaturized by standard microelectronic fabrication techniques to allow maximum thermal coupling.
Still another advantage is that the frequency of the ring oscillator may readily be measured to 1 part in 1011, thus making possible extremely precise temperature measurements.
The features and advantages summarized above in addition to other aspects of the present invention will become more apparent from the description, presented in conjunction with the following drawings.
FIG. 1 is a circuit diagram of the thermometric ring oscillator.
FIG. 2 is a detailed circuit diagram of a single inverter.
FIG. 3 is an example of ring oscillator frequency versus temperature for higher temperatures.
FIG. 4 is an example of ring oscillator frequency versus temperature for lower temperatures.
The following description is presented solely for the purpose of disclosing how the present invention may be made and used. The scope of the invention is defined by the claims.
Referring to FIG. 1, a thermometric oscillator 10 comprises an odd number of inverters 12 connected serially in a closed feedback loop. Other arrangements of an odd number of inverters 12 may be used, for example, a single inverter. Generally, a greater number of inverters has a lower ambient temperature oscillating frequency and a wider frequency variation over a percentage of temperature change than a smaller number of inverters. An optional feedback impedance (not shown) may also be used. As the temperature environment of thermometric oscillator 10 changes, the switching speed of the transistors of which the inverters are comprised changes, causing the oscillating frequency to change. FIGS. 3 and 4 are plots of frequency versus temperature for exemplary ring oscillator circuits. Thermometric ring oscillator 10 may be miniaturized by standard microelectronic fabrication techniques. Miniaturized thermometric oscillator 10 may be placed in close proximity to the point where a temperature measurement is desired, for example, on an integrated circuit microchip to ensure optimum thermal coupling. The nominal oscillating frequency of thermometric oscillator 10 may readily be measured to 1 part in 1011, thus making possible extremely precise temperature measurements.
An antenna 14 may be located at a convenient location to transform electromagnetic radiation from thermometric oscillator 10 into an electrical signal. A receiver 16 is connected to antenna 14 to receive the electrical signal, measure the frequency of the signal, and determine the corresponding temperature of thermometric oscillator 10. The temperature may be determined, for example, from a lookup or calibration table. The temperature may be presented on a display 18 or from an output 19 in digital or analog form to other devices.
FIG. 2 shows a detailed circuit diagram of an exemplary inverter 20 that may be used for making thermometric ring oscillator 10 in FIG. 1. A voltage source 22 biases inverter 20 to operate as an amplifier. Other oscillator circuits may be used, such as junction transistor circuits. The nominal oscillating frequency may be chosen to accommodate a wide variety of applications by selecting the number of inverters comprising thermometric ring oscillator 10, and may range over the frequency spectrum from about 100 GHZ down to the sub-audio frequency range of about 1 Hz. A typical range for the nominal oscillating frequency is from about 10 MHZ to about 150 MHZ. Changes in temperature may be detected by measuring the corresponding changes in the nominal oscillating frequency. Exemplary values of oscillating frequency versus temperature for thermometric ring oscillator 10 are plotted in FIGS. 3 and 4.
Other modifications, variations, and applications of the present invention may be made in accordance with the above teachings other than as specifically described to practice the invention within the scope of the following claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3596262 *||Jan 8, 1968||Jul 27, 1971||Southwest Res Inst||Telemetry measuring apparatus|
|US3971362 *||Oct 27, 1972||Jul 27, 1976||Miniature ingestible telemeter devices to measure deep-body temperature|
|US4025912 *||Jul 19, 1976||May 24, 1977||The United States Of America As Represented By The Secretary Of The Navy||Method and apparatus for remotely transducing and transmitting pressure and temperature changes|
|US4140999 *||May 3, 1976||Feb 20, 1979||Robertshaw Controls Company||Transformer hot spot detection system|
|US4297557 *||May 3, 1976||Oct 27, 1981||Robertshaw Controls Company||Microwave oven temperature indicator and control means|
|US4448549 *||Feb 9, 1982||May 15, 1984||Citizen Watch Company Limited||Temperature sensing device|
|US4471354 *||Nov 23, 1981||Sep 11, 1984||Marathon Medical Equipment Corporation||Apparatus and method for remotely measuring temperature|
|US4549818 *||Dec 2, 1983||Oct 29, 1985||Citizen Watch Co., Ltd.||Temperature detector|
|US4658407 *||Dec 20, 1984||Apr 14, 1987||Kabushiki Kaisha Toshiba||Electronic clinical thermometer with power shut-off at maximum temperature|
|US4689621 *||Mar 31, 1986||Aug 25, 1987||Temperature responsive transmitter|
|US4874252 *||Oct 25, 1988||Oct 17, 1989||W. C. Heraeus Gmbh||Electronic thermometer|
|US4918423 *||Jul 25, 1988||Apr 17, 1990||Bridgestone Corporation||Tire inspection device|
|US5214668 *||Sep 30, 1991||May 25, 1993||Nec Corporation||Temperature detector and a temperature compensated oscillator using the temperature detector|
|US5374822 *||Jan 24, 1989||Dec 20, 1994||Robert Bosch Gmbh||Optical transmitter for producing an optical signal indicative of temperature|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5965817 *||Jul 28, 1998||Oct 12, 1999||Quasar International, Inc.||Temperature compensation of resonant frequency measurements for the effects of temperature variations|
|US6948388||Dec 18, 2003||Sep 27, 2005||The United States Of America As Represented By The Secretary Of The Navy||Wireless remote sensor|
|US7066643 *||Mar 26, 2004||Jun 27, 2006||Sunplus Technology Co,Ltd.||Radio frequency temperature sensor and method of calibrating temperature therefor|
|US7215212||Apr 12, 2004||May 8, 2007||General Electric Company||Apparatus for monitoring temperature and method for operating same|
|US7636052||Dec 21, 2007||Dec 22, 2009||Chevron U.S.A. Inc.||Apparatus and method for monitoring acoustic energy in a borehole|
|US7810993||Feb 6, 2008||Oct 12, 2010||Chevron U.S.A. Inc.||Temperature sensor having a rotational response to the environment|
|US7841234||Jul 30, 2007||Nov 30, 2010||Chevron U.S.A. Inc.||System and method for sensing pressure using an inductive element|
|US7863907||Feb 6, 2008||Jan 4, 2011||Chevron U.S.A. Inc.||Temperature and pressure transducer|
|US8083405||Oct 8, 2010||Dec 27, 2011||Chevron U.S.A. Inc.||Pressure sensor having a rotational response to the environment|
|US8106791||Apr 13, 2007||Jan 31, 2012||Chevron U.S.A. Inc.||System and method for receiving and decoding electromagnetic transmissions within a well|
|US8143906||Nov 24, 2010||Mar 27, 2012||Chevron U.S.A. Inc.||Temperature and pressure transducer|
|US8261607||Oct 4, 2010||Sep 11, 2012||Chevron U.S.A. Inc.||System and method for sensing pressure using an inductive element|
|US8353677||Oct 5, 2009||Jan 15, 2013||Chevron U.S.A. Inc.||System and method for sensing a liquid level|
|US8390471||Sep 7, 2007||Mar 5, 2013||Chevron U.S.A., Inc.||Telemetry apparatus and method for monitoring a borehole|
|US8784068||Dec 24, 2012||Jul 22, 2014||Chevron U.S.A. Inc.||System and method for sensing a liquid level|
|US20050135456 *||Mar 26, 2004||Jun 23, 2005||Hsin-Chou Lee||[radio frequency temperature sensor and method of calibrating temperature therefor]|
|US20050225415 *||Apr 12, 2004||Oct 13, 2005||Mahony Michael J||Apparatus for monitoring temperature and method for operating same|
|U.S. Classification||374/117, 374/170, 331/66, 331/57, 340/870.17|
|Sep 21, 1995||AS||Assignment|
Owner name: NAVY, UNITED STATES OF AMERICA, AS REPRESENTED BY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CLAYTON, STANLEY R.;ROSER, MARK R.;RUSSELL, STEPHEN D.;AND OTHERS;REEL/FRAME:007684/0792
Effective date: 19950920