SYSTEM AND METHOD FOR A REFERENCE CHAMBER WITH A HOUSING AND A DEFLECTABLE STRUCTURE

• US 20190041363A1
• Filed: 08/02/2018
• Published: 02/07/2019
• Est. Priority Date: 08/03/2017
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Tumpold, David, Dehe, Alfons
• Granted Patent: US 11,549,917 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 2291/021 Gases
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: G01N 29/2425 optoacoustic fluid cells therefor
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects
• CPC Class Codes: G01N 29/4436 with a reference signal amplitude comparison G01N29/48

Abstract

A reference chamber for a fluid sensor comprises a housing, a deflectable structure, which is arranged movably within the housing, a control device configured to drive the deflectable structure at a first point in time such that the deflectable structure assumes a defined position, and to drive the deflectable structure at a second point in time such that the deflectable structure moves out of the defined position and a movement of the deflectable structure in the housing is obtained. The reference chamber comprises an evaluation device configured to determine a movement characteristic of the movement of the deflectable structure on the basis of the moving into the defined position or on the basis of the moving out of the defined position and to determine an atmospheric property in the housing on the basis of the movement characteristic.

Claims

1. A reference chamber for a fluid sensor, comprising:

a housing;

a deflectable structure, which is arranged movably within the housing;

a control device configured to drive the deflectable structure at a first point in time to cause the deflectable structure to move into a defined position, and to drive the deflectable structure at a second point in time to cause the deflectable structure to move out of the defined position, wherein movement of the deflectable structure in the housing is obtained; and

an evaluation device configured to determine a movement characteristic of the movement of the deflectable structure based on the moving into the defined position or based on the moving out of the defined position, and to determine an atmospheric property in the housing based on the movement characteristic.

2. The reference chamber as claimed in claim 1, further comprising an electrode pair, wherein the deflectable structure has a first electrode of the electrode pair, and wherein a second electrode of the electrode pair is arranged adjacent to the first electrode;

and wherein the control device is configured to drive the deflectable structure by applying a voltage difference to the electrode pair.

3. The reference chamber as claimed in claim 2, wherein at least one electrode of the electrode pair comprises an insulation structure configured to prevent an electrical short circuit between the first electrode and the second electrode during a mechanical contact between the first electrode and the second electrode.

4. The reference chamber as claimed in claim 1, wherein the deflectable structure in the defined position mechanically contacts a supporting structure or an electrode.

5. The reference chamber as claimed in claim 4, wherein the control device is further configured to drive the deflectable structure, to cause mechanical contact during a bounce movement.

6. The reference chamber as claimed in claim 1, wherein the movement comprises an oscillation of the deflectable structure into the defined position or an oscillation of the deflectable structure out of the defined position into a rest position.

7. The reference chamber as claimed in claim 1, wherein the deflectable structure comprises an electrode that is part of an electrode pair, and wherein the control device is configured to apply to the electrode pair at the first point in time a voltage that is greater than a snap-in voltage of the electrode pair, and to apply to the electrode pair at the second point in time a voltage that is less than or equal to a release voltage that leads to a release of a first electrode of the electrode pair from a second electrode of the electrode pair.

8. The reference chamber as claimed in claim 1, further comprising an actuator coupled to the deflectable structure, wherein the control device is configured to control the actuator to cause the deflectable structure to move into the defined position or out of the defined position.

9. The reference chamber as claimed in claim 1, wherein the movement characteristic provides information regarding a change in a movement resistance of a filling medium in the housing, said movement resistance acting on the deflectable structure.

10. The reference chamber as claimed in claim 1, wherein the movement characteristic comprises at least one of a dead time until the deflectable structure moves out of the defined position, an oscillation frequency of the deflectable structure, an oscillation amplitude of the deflectable structure, an oscillation damping of the oscillation of the deflectable structure, a slope of the movement of the deflectable structure, a limiting frequency of the deflectable structure or a resonant frequency of the oscillation of the deflectable structure.

11. The reference chamber as claimed in claim 1, wherein the atmospheric property relates to at least one from a pressure within the housing, a composition of a fluid in the housing or a number of fluid molecules in the housing.

12. The reference chamber as claimed in any claim 1, wherein the evaluation device is configured to detect the movement characteristic during a calibration interval, to store information based on the movement characteristic in a memory as reference value, and once again to detect the movement characteristic during a checking interval, to compare the detected movement characteristic with the stored information to obtain a comparison result, and to determine the atmospheric property based on the comparison result.

13. The reference chamber as claimed in claim 12, wherein the calibration interval is a first calibration interval, and wherein the evaluation device is configured to detect the movement characteristic during a second calibration interval and to store information based on the movement characteristic of the second calibration interval in the memory as a new reference value.

14. The reference chamber as claimed in claim 1, wherein the evaluation device is configured to output a signal indicating a deviation of the atmospheric property from a reference state taking account of a tolerance range.

15. The reference chamber as claimed in claim 1, wherein the evaluation device is configured to indicate a leak in the housing or an imminent failure of the reference chamber based on the atmospheric property.

16. The reference chamber as claimed in claim 1, wherein the control device is configured to wait between the first point in time and the second point in time for a time interval to elapse to enable a rest state of the deflectable structure.

17. The reference chamber as claimed in claim 1, wherein the housing is formed in a hermetically sealed fashion in a functional operating state, wherein the evaluation device is configured to ascertain an untightness of the housing based on the atmospheric property varying over time.

18. The reference chamber as claimed in claim 1, wherein the housing is filled with a reference gas or a low pressure when the housing is in a functional state.

19. The reference chamber as claimed in claim 1, wherein the deflectable structure is part of a pressure transducer.

20. The reference chamber as claimed in claim 19, wherein the pressure transducer is a microphone.

21. The reference chamber as claimed in claim 1, wherein the evaluation device is configured to determine the movement characteristic optically or electrically.

22. The reference chamber as claimed in claim 1, wherein the deflectable structure comprises a first electrode of an electrode pair, the first electrode and a second electrode of the electrode pair are closed, and a closed volume is present between the first and second electrode of the electrode pair.

23. The reference chamber as claimed in claim 1, wherein the deflectable structure is a membrane.

24. A fluid sensor comprising:

an emitter configured to emit a thermal radiation;

a reference chamber configured to receive at least one portion of the thermal radiation, the reference chamber comprising;

a housing,

a deflectable structure, which is arranged movably within the housing,

a control device configured to drive the deflectable structure at a first point in time to cause the deflectable structure to move into a defined position, and to drive the deflectable structure at a second point in time to cause the deflectable structure to move out of the defined position, wherein movement of the deflectable structure in the housing is obtained,

an evaluation device configured to determine a movement characteristic of the movement of the deflectable structure based on the moving into the defined position or based on the moving out of the defined position and to determine an atmospheric property in the housing based on the movement characteristic; and

an absorption path arranged between the emitter and the reference chamber;

wherein the fluid sensor is configured to perform a photoacoustic evaluation of a fluid arranged in the absorption path, the photoacoustic evaluation comprising evaluating the movement of the deflectable structure caused by the thermal radiation.

25. The fluid sensor as claimed in claim 24, wherein the evaluation device is configured to evaluate the movement of the deflectable structure that is caused by the thermal radiation in the reference chamber for the photoacoustic evaluation during a measurement interval, and to determine a fluid property of the fluid arranged in the absorption path based the evaluation.

26. The fluid sensor as claimed in claim 24, wherein the fluid sensor is configured to drive the emitter with a rectangular signal.

27. The fluid sensor as claimed in claim 24, wherein the deflectable structure comprises a first electrode of an electrode pair, wherein the fluid sensor is configured to apply to the electrode pair a voltage that is less than a snap-in voltage for the evaluation of the movement of the deflectable structure that is generated by the thermal radiation.

28. The fluid sensor as claimed in claim 24, wherein the fluid sensor comprises a gas sensor.

29. The fluid sensor as claimed in claim 24, wherein the reference chamber comprises a plurality of reference chambers, the absorption path comprises a plurality of absorption paths, and a corresponding absorption path of the plurality of absorption paths is assigned to each reference chamber.

30. The fluid sensor as claimed in claim 29, wherein a first reference chamber and a second reference chamber of the plurality of reference chambers in a functional operating state have an identical atmospheric property in the housing, wherein the evaluation device is configured to compare the movement characteristic of the first and second reference chamber with one another and, in the case of a deviation outside a tolerance range, to output a signal indicating a fault state of the fluid sensor.

31. An apparatus comprising a fluid sensor as claimed in claim 24.

32. The apparatus as claimed in claim 31, wherein the apparatus comprises an automobile, a cellular phone or a building.

33. A method for providing a reference chamber comprising the following steps:

providing a housing;

arranging a deflectable structure movably within the housing;

arranging a control device configured to drive the deflectable structure at a first point in time to cause the deflectable structure to move into a defined position, and to drive the deflectable structure at a second point in time to cause the deflectable structure to move out of the defined position, wherein a movement of the deflectable structure in the housing is obtained;

arranging an evaluation device configured to determine a movement characteristic of the movement of the deflectable structure based on the moving into the defined position or based on the moving out of the defined position, and to determine an atmospheric property in the housing based on the movement characteristic.

34. A method for determining an atmospheric property in a reference chamber having a deflectable structure arranged movably within a housing, the method comprising:

moving the deflectable structure at a first point in time into a defined position;

moving the deflectable structure at a second point in time out of the defined position, wherein a movement of the deflectable structure in the housing is obtained;

determining a movement characteristic of the movement of the deflectable structure based on the moving into the defined position or based on the moving out of the defined position; and

determining an atmospheric property in the housing based on the movement characteristic.

35. A non-transitory computer readable medium with an executable program stored thereon, wherein the program instructs a processor to perform the method as claimed in claim 34.