Sensor with a vibrating member in a cavity with integrated anomaly detection

Patent metadata

Field	Value
Publication number	US-9423292-B2
Application number	US-201314409432-A
Country	US
Kind code	B2
Filing date	May 28, 2013
Priority date	Jun 22, 2012
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

The invention relates to vibrating micro-systems, and notably but not exclusively to pressure, acceleration, or angular speed micro-sensors with a resonator in an evacuated cavity.
The resonator ( 10 ) with a vibrating element is placed in an oscillating circuit controlled by a closed-loop control, the oscillating circuit supplying an oscillating signal y(t) at a resonance frequency Fp representing the measurement of a physical quantity. The resonance frequency is calculated by counting pulses over a time window. The sensor furthermore comprises means for calculating a continuity parameter Pc representing the variations in the result of the calculation of the resonance frequency over the course of the successive time windows, and means for comparing the parameter Pc with a threshold in order to deduce from this information on the degradation of the precision of the sensor.

First claim

The invention claimed is:

1. A resonator measurement sensor, comprising
a resonator with a vibrating element placed in an oscillating circuit controlled by a closed-loop control, the oscillating circuit supplying an oscillating signal y(t) at a resonance frequency Fp representing the measurement of a physical quantity,
and a processing circuit for calculating this resonance frequency,
the processing circuit comprising means for conditioning the oscillating signal so as to produce a square-wave signal at the resonance frequency Fp, means for periodically producing a counting time window, at least one counter incremented by the square-wave signal at the resonance frequency during the counting time window, and means for calculating the resonance frequency from the content of the counter,
the sensor being characterized in that it furthermore comprises means for calculating a continuity parameter Pc representing the variations in the result of the calculation of the resonance frequency over the course of successive time windows, and means for comparing the parameter Pc with a threshold in order to deduce from this information on the degradation in the precision of the sensor.

2. The sensor as claimed in claim 1 , wherein the processing circuit comprises a first counter receiving the square-wave signal at the resonance frequency and counting a number N of periods of the resonance frequency Fp over the duration Tc of the window, a second counter receiving a signal at a clock frequency Fclk higher than the resonance frequency and counting a number n of clock periods over the N periods of the resonance frequency, the resonance frequency Fp calculated being equal to the clock frequency multiplied by the ratio N/n.

3. The sensor as claimed in claim 1 , wherein the continuity parameter is calculated periodically at the frequency of the counting time window, and its value Pc i for a window of rank i is equal to Fpi−Fpi−1, where Fpi is the resonance frequency calculated from the counting window of rank i and Fpi−1 is the resonance frequency calculated from the preceding counting window of rank i−1.

4. The sensor as claimed in claim 1 , wherein the processing circuit comprises a first counter receiving the square-wave signal at the resonance frequency and counting a number N of periods of the resonance frequency Fp over the duration Tc of the window, and a second counter receiving a signal at a clock frequency Fclk higher than the resonance frequency and counting a number n of clock periods over the N periods of the resonance frequency and the threshold with respect to which the continuity parameter is compared is equal to Fclk/2n or in the range between Fclk/2n and Fclk/n.

5. The sensor as claimed in claim 1 , wherein the vibrating element is placed in a cavity under a high vacuum, the detection of the exceeding of the threshold being a probable indication of a loss of vacuum.

6. The sensor as claimed in claim 2 , wherein the continuity parameter is calculated periodically at the frequency of the counting time window, and its value Pc i for a window of rank i is equal to Fpi−Fpi−1, where Fpi is the resonance frequency calculated from the counting window of rank i and Fpi−1 is the resonance frequency calculated from the preceding counting window of rank i−1.

7. The sensor as claimed in claim 6 , wherein the vibrating element is placed in a cavity under a high vacuum, the detection of the exceeding of the threshold being a probable indication of a loss of vacuum.

Assignees

• Thales Sa

Inventors

• Quer Regis
• Planchette Yann
• Muguet Jean-Michel

Classifications

• G01L9/0019 Primary

  of a semiconductive element · CPC title

• G01C19/5776

  Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719 · CPC title

• G01L27/007

  Malfunction diagnosis, i.e. diagnosing a sensor defect · CPC title

• G01P15/097

  by vibratory elements · CPC title

• G01H13/00 Primary

  Measuring resonant frequency · CPC title