Method of operating LC sensors, corresponding system and apparatus

Patent metadata

Field	Value
Publication number	US-10859617-B2
Application number	US-201816136121-A
Country	US
Kind code	B2
Filing date	Sep 19, 2018
Priority date	Sep 10, 2015
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

In one embodiment, an inductive/LC sensor device includes: an energy storage device for accumulating excitation energy, an LC sensor configured to oscillate using energy accumulated in the energy storage device and transferred to the LC sensor, an energy detector for detecting the energy accumulated in the energy storage device reaching a charge threshold, and at least one switch coupled with the energy detector for terminating accumulating excitation energy in the energy storage device when the charge threshold is detected having been reached by the energy detector.

First claim

The invention claimed is:

1. An LC sensor device, comprising:
an energy storage device configured to accumulate excitation energy,
an LC sensor coupled to the energy storage device and configured to oscillate when energized by the excitation energy from the energy storage device,
an energy detector configured to detect the excitation energy in the energy storage device reaching a charge threshold,
a first switch configured to selectively couple the LC sensor with an energy source; and
a second switch connected in series with the LC sensor and positioned between the LC sensor and a ground terminal and being configured to be controlled by the energy detector.

2. The LC sensor device of claim 1 , wherein the energy storage device includes a reference capacitor coupled in parallel to the series connection of the LC sensor and the second switch.

3. The LC sensor device of claim 1 , wherein the second switch is coupled in series to the LC sensor and the energy storage device includes a reference capacitor coupled in parallel with a combination of the LC sensor and the second switch.

4. The LC sensor device of claim 1 , wherein:
the energy storage device includes a reference capacitor coupled in series to the LC sensor, and
the energy detector is configured close the first switch to electrically couple the LC sensor to the energy source and open the second switch to remove a short-circuit across the reference capacitor while the LC sensor is electrically coupled to the energy source by the first switch.

5. The LC sensor device of claim 1 , wherein:
the energy storage device includes a reference capacitor, and
the energy detector is configured to detect the energy accumulated reaching the charge threshold by detecting a voltage across the reference capacitor reaching a voltage threshold.

6. The LC sensor device of claim 1 , wherein when the first and second switches are open there is a zero-voltage drop across the LC sensor.

7. The LC sensor device of claim 1 , wherein at least one of the energy detector, the first switch, and the second switch is controlled by a controller unit.

8. The LC sensor device of claim 1 , wherein the energy detector includes a Schmitt trigger configured to detect the excitation energy in the energy storage device reaching the charge threshold, the LC sensor device including a microcontroller configured to control the first and second switches based on an output of the Schmitt trigger.

9. A method comprising:
electrically coupling an energy storage device to an energy source via a first switch;
accumulating excitation energy in the energy storage device while the energy storage device is electrically coupled to the energy source by the first switch;
detecting the excitation energy accumulated reaching a charge threshold;
opening the first switch in response to detecting the excitation energy accumulated reaching the charge threshold; and
oscillating an LC sensor, while the first switch is open, using the excitation energy accumulated by the energy storage device, wherein:
the accumulating includes accumulating the excitation energy while the energy storage device is electrically coupled to the energy source via a closed second switch and the first switch, the method includes transferring charge from the energy storage device to the LC sensor while the first switch is open and the second switch electrically couples the LC sensor to ground, and the oscillating includes oscillating the LC sensor in response to opening the second switch in response to detecting the excitation energy accumulated reaching the charge threshold.

10. The method of claim 9 , wherein:
the accumulating includes:
a first charge phase in which the closed second switch electrically couples the LC sensor to the ground while the first switch electrically couples the energy storage device to the energy source; and
a second charge phase in which the second switch is open while the first switch electrically couples the energy storage device to the energy source; and
the oscillating includes oscillating the LC sensor in response to opening the first switch in response to detecting the excitation energy accumulated reaching the charge threshold.

11. An LC sensor device, comprising:
an energy storage device configured to accumulate excitation energy,
an LC sensor coupled to the energy storage device and configured to oscillate when energized by the excitation energy in the energy storage device,
an energy detector configured to detect the excitation energy in the energy storage device reaching a charge threshold,
a first switch coupled with the energy detector and configured to electrically couple the LC sensor with an energy source and cause the excitation energy to be transferred from the energy source to the energy storage device while the first switch is closed, wherein the energy detector is configured to open the first switch in response to detecting that the charge threshold has been reached by the excitation energy in the energy storage device, wherein the LC sensor is configured to oscillate while the first switch is open, and
a second switch connected in series with the LC sensor and positioned between the LC sensor and a ground terminal, the second switch being configured to be controlled by the energy detector.

12. The LC sensor device of claim 11 , wherein:
the energy storage device includes a reference capacitor.

13. The LC sensor device of claim 11 , wherein the second switch is coupled in series to the LC sensor and the energy storage device includes a reference capacitor coupled in parallel with a combination of the LC sensor and the second switch.

14. The LC sensor device of claim 13 , wherein the energy detector includes a Schmitt trigger configured to detect the excitation energy in the energy storage device reaching the charge threshold, the LC sensor device including a microcontroller configured to control the first and second switches based on an output of the Schmitt trigger.

15. A fluid flow sensing device, comprising:
a sense structure configured to be moved by a fluid flow; and
an LC sensor device coupled to the sense structure and configured to sense movement of the sense structure, the LC sensor including:
an energy storage device configured to accumulate excitation energy,
an LC sensor coupled to the energy storage device and configured to oscillate when energized by the excitation energy in the energy storage device,
an energy detector configured to detect the excitation energy in the energy storage device reaching a charge threshold,
a first switch coupled with the energy detector and configured to electrically couple the LC sensor with an energy source and cause the excitation energy to be transferred from the energy source to the energy storage device while the first switch is closed, wherein the energy detector is configured to open the first switch in response to detecting that the charge threshold has been reached by the excitation energy in the energy storage device, wherein the LC sensor is configured to oscillate while the first switch is open, and
a second switch connected in series with the LC sensor and positioned between the LC sensor and a ground terminal, the second switch being configured to be controlled by the energy detector.

16. The LC sensor device of claim 15 , wherein the energy detector includes a Schmitt trigger configured to detect the excitation energy in the energy storage device reaching the charge threshold, the LC sensor device including a microcontroller configured to control the first and second switches based on an

Assignees

• St Microelectronics Srl

Inventors

• Condorelli Riccardo
• Mangano Daniele

Classifications

• G01D5/20 Primary

  by varying inductance, e.g. by a movable armature · CPC title

• H03K17/954

  controlled by an oscillatory signal · CPC title

• H03K17/9537

  in a resonant circuit · CPC title

• G01R27/26 Primary

  Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants {; Measuring impedance or related variables} · CPC title