Dynamic Sensor for Measurement Device

• US 20200136617A1
• Filed: 10/25/2019
• Published: 04/30/2020
• Est. Priority Date: 10/25/2018
• Status: Active Grant

• Current Assignee: Pepperl + Fuchs GmbH
• Original Assignee: Pepperl + Fuchs GmbH
• Inventors: Kuhn, Thomas, Vater, Jochen, Braunsmann, Christoph
• Granted Patent: US 11,075,632 B2
• Time in Patent Office: Days
• CPC Class Codes: H03K 17/9502 Measures for increasing reliability
• CPC Class Codes: H03K 17/9532 with variable frequency
• CPC Class Codes: H03K 17/9535 with variable amplitude
• CPC Class Codes: H03K 17/9547 with variable amplitude
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2217/9401 Calibration techniques

Abstract

An oscillating sensor device, particularly for a proximity sensor, for sensing a dynamic change of attenuation caused by a measurable physical effect includes an oscillator including a resonance circuit and an amplifier fed back to the resonance circuit and configured to maintain oscillation of the oscillator, and a control unit configured to control the open loop gain of the oscillator. The amplifier comprises a non-linear gain characteristics defining an operating point at a preset amplitude of oscillation. The control unit is configured to control the open loop gain of the oscillator so that the operating point is set to a preset amplitude of the oscillation.

Claims

1. An oscillating sensor device, particularly for a proximity sensor, for sensing a dynamic change of attenuation caused by a measurable physical effect, comprising:

an oscillator including a resonance circuit and an amplifier fed back to the resonance circuit and configured to maintain oscillation of the oscillator wherein the amplifier comprises a non-linear gain characteristics defining an operating point at a preset amplitude of oscillation, and

a control unit configured to control the open loop gain of the oscillator and to control the open loop gain of the oscillator so that the operating point is set to a preset amplitude of the oscillation.

2. The oscillating sensor device according to claim 1, wherein the dynamic of adapting the open loop gain is lower than the dynamic of change of attenuation due to an object to be detected.

3. The oscillating sensor device according to claim 1, wherein the amplifier (22) has a gain stage which is feedback coupled with the resonance circuit by means of a feedback circuit including a variable resistance to be controlled by the control unit in order to control the open loop gain of the oscillator, wherein particularly the feedback coupling is provided by a trimming resistor with a fixed resistance and a controllable switch so that an effective variable resistance is set by controlling the switch with a modulated control signal.

4. Oscillating sensor device according to claim 1, wherein the amplifier has a gain stage, wherein the control unit is configured to control the gain of the gain stage in order to control the open loop gain of the oscillator, wherein particularly the gain stage is configured as a voltage controlled gain stage to be controlled by a voltage gain control signal provided by the control unit or the gain stage includes an internal feedback to be controlled by a PWM gain control signal provided by the control unit.

5. The oscillating sensor device according to claim 1, wherein the control unit comprises an amplitude determination unit for determining a current amplitude value of the oscillation amplitude, a control deviation unit for determining an amplitude deviation between the preset amplitude and the current amplitude value, and a controlling block for implementing a control with an integration portion to provide a control signal for controlling the open loop gain of the oscillator.

6. The oscillating sensor device according to claim 5, wherein the controlling block of the control unit is configured to provide an integration portion with a first integration factor.

7. The oscillating sensor device according to claim 6, wherein the controlling block of the control unit is configured to provide the integration portion with the first integration factor in case of a positive amplitude deviation between a preset amplitude and a current amplitude of oscillation and with a second integration factor for a negative amplitude deviation, wherein the first integration factor and the second integration factor are different.

8. The oscillating sensor device according to claim 6, wherein the control unit is configured to provide a proportional and/or a differential portion for either the positive or the negative amplitude deviation.

9. The oscillating sensor device according to claim 1, wherein the control unit is configured to adjust the open loop gain of the oscillator so that the oscillation amplitude corresponds to the preset amplitude after a first time after a positive amplitude deviation larger than a given first amplitude deviation threshold has been detected.

10. The oscillating sensor device according to claim 9, wherein the control unit is configured to adjust the open loop gain so that the oscillation amplitude corresponds to the preset amplitude after a second time after a negative amplitude deviation larger than a given second amplitude deviation threshold has been detected, wherein the second time is shorter than the first time and wherein the first amplitude deviation threshold is equal, higher or lower than the second amplitude deviation threshold.

11. A measurement device comprising an oscillating sensor device according to claim 1 and an analyzing unit configured to receive the amplitude deviation and to derive a sensor signal therefrom.

12. The measurement device according to claim 11, wherein a frequency determination unit is provided and is configured to determine an oscillation frequency shift caused by a dynamic object, wherein the analyzing unit is configured to receive the oscillation frequency and to determine a kind of dynamic object by the amplitude deviation and by the frequency shift determined.

13. A proximity sensor comprising an oscillating sensor device according to claim 1 wherein the resonance circuit includes a sensing coil.

15. The oscillating sensor device according to claim 3, wherein:

the amplifier has a gain stage;

the control unit is configured to control the gain of the gain stage in order to control the open loop gain of the oscillator; and

one of;

the gain stage is configured as a voltage controlled gain stage to be controlled by a voltage gain control signal provided by the control unit;

or

the gain stage includes an internal feedback to be controlled by a PWM gain control signal provided by the control unit.

16. The oscillating sensor device according to claim 15, wherein the control unit comprises:

an amplitude determination unit for determining a current amplitude value of the oscillation amplitude;

a control deviation unit for determining an amplitude deviation between the preset amplitude and the current amplitude value; and

a controlling block for implementing a control with an integration portion to provide a control signal for controlling the open loop gain of the oscillator.

17. The oscillating sensor device according to claim 7, wherein the control unit is configured to provide a proportional and/or a differential portion for either the positive or the negative amplitude deviation.

14. A method for operating an oscillating sensor device, particularly for a proximity sensor, for sensing a dynamic change of attenuation caused by a measurable physical effect, which comprises:

providing the oscillation sensor device with an oscillator including a resonance circuit and an amplifier fed back to the resonance circuit and configured to maintain oscillation of the oscillator, the amplifier comprising a non-linear gain characteristics defining an operating point at a preset amplitude of oscillation,

controlling the open loop gain of the oscillator so that the operating point is set to a preset amplitude of the oscillation.