Method for detecting, method for compensating, method for operating and pressure sensor

Abstract

The present invention relates to a method (32) for detecting the signal influence (28) of a coating material (22) on a sensor element (18) of a pressure sensor (14), comprising the steps of: providing (12) a pressure sensor (14) that provides a measurement signal (16) based on the deflection of the sensor element (18) related to the pressure (p) on the pressure sensor (14), and the pressure sensor having a coating material (22) on the sensor element (18) facing the sensor environment (20) and influencing the measurement signal (16); exciting (44) with an electrical excitation signal (46). The invention relates to a sensor element (18); detecting (48) the response signal (50) of the sensor element (18) to an excitation signal (46); comparing (52) the response signal (50) with a stored reference signal (54); wherein, by comparing (52) the frequency change trend (56) of the response signal (50) with the frequency change trend (58) of the reference signal (54), an influence parameter (C) is calculated as at least one quantitative characteristic quantity of the coating material (22), which influences the signal (28) of the measurement signal (16) due to the acceleration sensitivity of the pressure sensor (14). The invention also relates to a method (26) for compensation, a method (10) for operation, and a pressure sensor (14).

Description

Technical Field

[0001] This invention relates to a method for detecting signal interference as described in the preamble of claim 1. Furthermore, the invention also relates to a method for compensating for signal interference, a method for operating a pressure sensor, and a pressure sensor itself. Background Technology

[0002] DE 10 2020 209 856 A1 discloses a method for determining the state of a pressure sensor having a deflectable micromechanical sensor structure. The method involves exciting the micromechanical sensor structure with an electrical excitation signal, detecting the response behavior of the sensor structure, comparing it to reference behavior, and thereby evaluating the sensor state in terms of the presence of deposits. This response behavior can be a resonant frequency or a quality factor. If the presence of deposits is inferred, corrective measures for removing the deposits are initiated. Summary of the Invention

[0003] According to the present invention, a method for detection is provided, having the features described in claim 1. This allows for the detection of the degree of signal influence on the measurement signal caused by the coating material, and preferably the calculation and compensation of the signal component affected by this influence. The pressure sensor can operate reliably even in the presence of deposits on the sensor element. The measurement accuracy of the pressure sensor is improved.

[0004] The pressure sensor can be a microprocessor-controlled pressure sensor (MEMS pressure sensor). This pressure sensor can be installed in vehicles, aircraft, watercraft, industrial products, and / or consumer products. Consumer products here can be mobile devices, especially smartphones or wearable devices, preferably smartwatches.

[0005] The sensor element can be a microelectromechanical (MEMS) sensor element used to convert applied pressure into an electrical measurement signal. The sensor element may include a sensor diaphragm that deflects according to the pressure. The measurement signal may depend on the deflection of the sensor diaphragm. For this purpose, the sensor element may have a piezoresistive, piezoelectric, optical, and / or capacitive conversion device. The pressure applied to the sensor element and to be measured can be an absolute pressure, preferably the ambient pressure of the sensor element's sensor environment, and / or a differential pressure, particularly the differential pressure between the front and back sides of the sensor element.

[0006] The pressure sensor can be a capacitive pressure sensor. The sensor element can have a movable electrode. This electrode can deflect relative to a fixed counter electrode. The measurement signal can depend on the distance between the electrode and the counter electrode related to the deflection of the sensor element.

[0007] Acceleration sensitivity is the lateral sensitivity of a pressure sensor to acceleration. In this case, the measurement signal indicating the pressure applied to the pressure sensor may be affected, thus interfering with the pressure measurement. Acceleration sensitivity may involve accelerations including gravitational acceleration and / or linear and / or rotational accelerations acting on the pressure sensor from external sources.

[0008] The signal influence of the coating material can be generated by the accelerating force acting on the sensor element, which is related to the mass and acceleration of the coating material. The accelerating force corresponds to the pressure component of the signal component that constitutes the signal influence in the measurement signal, which is related to the sensor element and the sensor area on which the accelerating force effectively acts.

[0009] The reference signal can be stored in a storage unit. The storage unit can be a component of the pressure sensor. The storage unit can be an integrated circuit, particularly an FPGA or ASIC. The storage unit can be associated with an electronic unit of the pressure sensor. This electronic unit can digitally convert and / or output the measurement signal.

[0010] The coating material can have a preferably sealed insulating substance that separates the sensor element from the sensor environment. The coating material can be formed from the insulating substance and deposits on the side of the insulating substance facing away from the sensor element and towards the sensor environment.

[0011] The isolating material may include gels and / or oils. The isolating material may be viscoelastic. The isolating material may be primarily, preferably solely, arranged to protect the sensor element from environmental influences. The isolating material may be liquid or semi-liquid. Solid and gaseous properties of the isolating material may be absent. The isolating material may partially or completely cover the sensor element.

[0012] Sediments can be undesirable materials, substances, or objects on an insulating material. Sediments can be dirt, organic and / or inorganic materials, water, snow, ice, dust, and / or sand.

[0013] The pressure sensor may have a housing in which an insulating material is housed. The housing may have an opening facing the sensor environment of the pressure sensor for transmitting pressure between the sensor environment and the sensor element or the insulating material. The sensor element may be arranged relative to the insulating material on a side facing away from the opening. The housing may house, preferably surround, or enclose the sensor element.

[0014] The excitation signal may include a frequency range that at least includes the expected resonant frequency of the sensor element. This excitation signal may be a timing frequency scan signal or a synchronous broadband frequency superposition signal. The frequency superposition signal may be a voltage pulse signal.

[0015] The excitation signal can have a time offset relative to the response signal. Excitation and detection of the response signal can be time-separated. The excitation signal can be conducted to the sensor element through an excitation element, such as an excitation electrode. Excitation and detection of the response signal can be performed simultaneously.

[0016] A quantitative characteristic quantity can take different values. Signal effects can be at least related to this characteristic quantity. This characteristic quantity can subsequently cause signal effects in a way that the signal effects are fundamentally dependent on the characteristic quantity and at least one other parameter. In addition to this influencing parameter, the acceleration acting on the pressure sensor will also cause signal effects.

[0017] When a deviation is found between the response signal and the reference signal, the influence parameter can be calculated. The calculation can be arranged based on this comparison. The influence parameter can be calculated quantitatively based on information from both the response signal and the reference signal, or calculated based solely on information from the response signal. Information from the response signal and / or the reference signal can be used when calculating the influence parameter.

[0018] In a preferred embodiment of the invention, it is advantageous that the influencing parameter includes the mass value of the coating material. The influencing parameter may correspond to this mass value, i.e., the mass of the coating material. The influencing parameter may directly or indirectly describe the mass value of the coating material.

[0019] One influencing parameter is the thickness of the coating material on the sensor element. Another influencing parameter is the thickness of the insulating material, particularly the gel layer thickness.

[0020] In an advantageous embodiment, the resonant frequency and / or the quality factor of the resonant peak in the frequency variation trend of the response signal are determined. The resonant frequency and quality factor are preferably related to the pressure and the mass of the coating material. A larger mass of coating material will decrease the resonant frequency and / or alter the resonant peak described by the quality factor.

[0021] The resonant frequency can correspond to the natural frequency of the sensor element with the coating material or a multiple of the natural frequency of the sensor element with the coating material.

[0022] In one particular embodiment of the invention, it is advantageous that the influencing parameters are calculated based on the resonant frequency and / or quality factor. The influencing parameters can be associated with the resonant frequency and / or quality factor.

[0023] The correlation between the influencing parameters and the resonant frequency and / or quality factor can be determined and stored before the pressure sensor is first put into operation. This correlation can be checked during the operation of the pressure sensor and changed as necessary.

[0024] In one particular embodiment of the invention, it is advantageous that the influencing parameters are calculated based on a known relationship between the resonant frequency in the frequency variation trend and the mass of the coating material. This known relationship can be stored in a storage unit.

[0025] In a particular configuration of the invention, it is advantageous that the influencing parameters are calculated based on a known relationship between the quality factor of the resonance peak and the mass of the coating material. Preferably, the influencing parameters are calculated based on a known relationship between, on the one hand, the resonant frequency and the quality factor, and on the other hand, the mass of the coating material.

[0026] Given the known relationships, other environmental influences, especially temperature, can be considered.

[0027] Known relationships can be stored in a memory cell. Known relationships can also be stored in a memory cell that also stores a reference signal. The memory cell can be a component of the pressure sensor. The memory cell can be an integrated circuit, particularly an FPGA or ASIC. The memory cell can be associated with the electronic unit of the pressure sensor. The electronic unit can digitally convert and / or output the measurement signal.

[0028] A preferred embodiment of the invention is advantageous in which the frequency variation trend of the reference signal is obtained through at least two measurements, each performed with the pressure sensor oriented differently from the direction of gravitational acceleration, and the response signal detected. The first measurement, with excitation and detection of the response signal, can be performed with the pressure sensor in a first orientation relative to gravitational acceleration, particularly a parallel orientation, while the second measurement, with excitation and detection of the response signal, can be performed with the pressure sensor in a second, opposite orientation relative to gravitational acceleration, particularly an antiparallel orientation.

[0029] The reference signal can be obtained before the pressure sensor is first put into operation. The reference signal can be obtained for a pressure sensor with the same or similar structure as described.

[0030] According to the present invention, a method for compensating for signal interference, having the features described in claim 8, is also proposed. Acceleration can be measured using an external acceleration sensor.

[0031] According to the present invention, a method for operating a pressure sensor having the features of claim 9 is also proposed.

[0032] According to the present invention, a pressure sensor having the features described in claim 10 is also proposed.

[0033] Further advantages and advantageous configurations of the invention will become apparent from the accompanying drawings. Attached Figure Description

[0034] The present invention will now be described in detail with reference to the accompanying drawings. The drawings show in detail: Figure 1 This invention provides a method for operating a pressure sensor in a specific embodiment.

[0035] Figure 2 This invention provides a method for obtaining a reference signal for a detection method in a specific embodiment.

[0036] Figure 3 The present invention relates to a pressure sensor according to a specific embodiment and a response signal when a method for detecting signal influence is executed.

[0037] Figure 4 : Figure 3 The pressure sensor and its response signal when sediment is present. Detailed Implementation

[0038] Figure 1 A method for operating a pressure sensor according to a specific embodiment of the present invention is illustrated. The method 10 for operating the pressure sensor first includes providing a pressure sensor 14 that provides a measurement signal 16 related to the deflection of a sensor element 18, which is related to a pressure p on the pressure sensor 14, and the pressure sensor having a coating material 22 on the sensor element 18 facing the sensor environment 20 and influencing the measurement signal 16. During operation of the pressure sensor 14, compensation 24 is performed by a compensation method 26 that compensates for the signal influence 28 caused by the coating material 22 on the sensor element 18 of the pressure sensor 14 due to acceleration sensitivity.

[0039] The coating material 22 may have an insulating substance that separates the sensor element 18 from the sensor environment 20, preferably sealing it. This insulating substance may be a gel.

[0040] The sensor element 18 may be a microelectromechanical sensor element 18 for converting the pressure p applied thereto into an electrical measurement signal 16, and includes a sensor diaphragm that can deflect according to the pressure p.

[0041] In addition to providing the pressure sensor 14, the compensation method 26 includes: calculating the influence parameter C of the coating material 22 by means of a method 32 for detecting the signal influence 28 of the coating material 22 on the sensor element 18 of the pressure sensor 14; measuring the acceleration a acting on the pressure sensor 14 having the sensor element 18 and the coating material 22; calculating the signal component 40 of the signal influence 28 in the measurement signal 16 based on the measured acceleration a and the calculated influence parameter C; and compensating the signal component 40 in the measurement signal 16 24.

[0042] A method 32 for detecting the signal influence 28 of the coated material 22 on the sensor element 18 of the pressure sensor 14, in addition to providing the pressure sensor 14, includes: stimulating the sensor element 18 with an electrical excitation signal 46; detecting the response signal 50 of the sensor element 18 to the excitation signal 46; and comparing the response signal 50 with a stored reference signal 54. The comparison 52 involves comparing the frequency variation trend 56 of the response signal 50 with the frequency variation trend 58 of the reference signal 54.

[0043] Based on comparison 52, for example, when there is a deviation between frequency change trends 56 and 58, an influence parameter C is calculated as at least one characteristic quantity of the coating material 22, wherein the influence parameter C causes a signal influence 28 on the measurement signal 16 through the acceleration sensitivity of the pressure sensor 14. The influence parameter C may include the mass value m of the coating material 22. When acceleration a acts on the pressure sensor 14, the mass of the coating material 22 causes an accelerating force acting on the sensor element 18 with a deflectable sensor diaphragm, which corresponds to the pressure component of the signal component 40 that causes the signal influence 28 in the measurement signal 16 in relation to the diaphragm area.

[0044] In the frequency variation trend 56 of the response signal 50, it is preferable to obtain the resonant frequency fr and the quality factor G of the resonant peak in the frequency variation trend 56. The influence parameter C is calculated in particular based on the resonant frequency fr and the quality factor G. For this purpose, the influence parameter C is calculated based on the known relationship 60 between the resonant frequency fr and the quality factor G in the frequency variation trend 56 and the influence parameter C (in particular the mass m of the coating material 22).

[0045] Figure 2 This illustration shows a method for obtaining a reference signal for a detection method according to a specific embodiment of the invention. The frequency variation trend 58 of the reference signal 54 is obtained, for example, in advance, particularly before the pressure sensor 14 is first put into operation, by at least two measurements, each measurement involving excitation 44 and detection 48 of the response signal 50 when the pressure sensor 14 is oriented differently from each other relative to the direction of gravitational acceleration. In the first measurement 62, the sensor element 18 is excited with an excitation signal 46. At this time, the pressure sensor 14 is oriented parallel to the direction of gravitational acceleration 64, meaning the coating material 22 is facing upwards. The response signal 50 of the sensor element 18 is then detected. In the second measurement 66, the pressure sensor 14 is oriented antiparallel to the direction of gravitational acceleration 64, i.e., the coating material 22 is facing downwards, and the sensor element 18 is excited with the excitation signal 46 and the response signal 50 of the sensor element 18 is detected.

[0046] Subsequently, in Comparison 68, the two response signals 50 are compared with each other, and the reference signal 54 is calculated from this comparison.

[0047] Figure 3 This illustration shows a pressure sensor according to a specific embodiment of the present invention, and its response signal when a method for detecting signal effects is performed. Figure 3 Figure a) shows a pressure sensor 14, which has a sensor element 18 and an insulating material, such as a gel, serving as a coating material 22 on the sensor element 18. Figure 3 Figure b) shows the response signal 50 of the sensor element 18 after the excitation signal is applied. Here, the frequency variation trend 56 of the response signal 50 has a resonant peak 70 at the resonant frequency fr. This resonant peak 70 has a quality factor G, which describes the width 72 of the resonant peak 70.

[0048] Figure 4 Show Figure 3 The pressure sensor in the middle and the response signal when performing a method for detecting the influence of the signal in the presence of sediment. Figure 4 Figure a) shows a pressure sensor 14, which has a sensor element 18 and an insulating material 74 with deposits 76. Therefore, the coating material 22 is formed of the insulating material 74 and the deposits 76. Figure 4 Figure b) shows the response signal 50 of the sensor element 18 after the excitation signal is applied. Here, the frequency change trend 58 of the response signal 50 has a greater than Figure 3 The resonant frequency fr in b) is smaller than the resonant frequency. The resonant peak 70 has a smaller resonant frequency than... Figure 3 The quality factor G in b) is a larger quality factor G, which is due to the higher damping of the resonant oscillation caused by the coating material 22.

Claims

1. A method (32) for detecting the signal influence (28) of a coated material (22) on a sensor element (18) of a pressure sensor (14), comprising the following steps: Provide (12) a pressure sensor (14) that provides a measurement signal (16) based on the deflection of the sensor element (18) in relation to the pressure (p) on the pressure sensor (14), and the pressure sensor has a coating material (22) on the sensor element (18) facing the sensor environment (20) and affecting the measurement signal (16). The sensor element (18) is excited by an electrical excitation signal (46). Detect (48) the response signal (50) of the sensor element (18) to the excitation signal (46). The response signal (50) is compared with the stored reference signal (54) (52). Its features are, Based on the comparison (52) of the frequency change trend (56) of the response signal (50) and the frequency change trend (58) of the reference signal (54), the influence parameter (C) is calculated as at least one quantitative characteristic quantity of the coating material (22), which in turn causes a signal influence (28) on the measurement signal (16) due to the acceleration sensitivity of the pressure sensor (14).

2. The method (32) for detection according to claim 1, characterized in that, The influencing parameter (C) includes the mass value (m) of the coating material (22).

3. The method (32) for detection according to claim 1 or 2, characterized in that, The resonant frequency (fr) and / or the quality factor (G) of the resonant peak (70) in the frequency variation trend (56) of the response signal (50) are obtained.

4. The method (32) for detection according to claim 3, characterized in that, The influence parameter (C) is calculated based on the resonant frequency (fr) and / or the quality factor (G).

5. The method (32) for detection according to claim 3 or 4, characterized in that, The influence parameter (C) is calculated based on the known relationship (60) between the resonant frequency (fr) in the frequency change trend (56) and the mass value (m) of the coating material (22).

6. The method (32) for detection according to any one of claims 3 to 5, characterized in that, The influence parameter (C) is calculated based on the known relationship (60) between the quality factor (G) of the resonance peak (70) and the mass value (m) of the coating material (22).

7. The method (32) for detection according to any one of the preceding claims, characterized in that, The frequency variation trend (58) of the reference signal (54) is obtained by at least two measurements, which are performed by exciting (44) and detecting (48) the response signal (50) when the pressure sensor (14) is oriented differently from each other relative to the direction of gravitational acceleration (64).

8. A method (26) for compensating for the signal influence (28) caused by the coating material (22) on the sensor element (18) of the pressure sensor (14) through acceleration sensitivity, comprising the following steps: Provide (12) a pressure sensor (14) that provides a measurement signal (16) based on the deflection of the sensor element (18) in relation to the pressure (p) on the pressure sensor (14), and the pressure sensor has a coating material (22) on the sensor element (18) facing the sensor environment (20) and affecting the measurement signal (16). The influence parameter (C) of the coating material (22) is calculated by the method for detection (32) according to any one of the preceding claims. The acceleration (a) acting on the pressure sensor (14) having the sensor element (18) and the coating material (22) is measured (34). The signal component (40) of the measured signal (16) is calculated based on the measured acceleration (a) and the calculated influence parameter (C). The signal component (40) in the measurement signal (16) is compensated (24).

9. A method (10) for operating a pressure sensor (14), comprising the following steps: Provide (12) a pressure sensor (14) that provides a measurement signal (16) based on the deflection of the sensor element (18) in relation to the pressure (p) on the pressure sensor (14), and the pressure sensor has a coating material (22) on the sensor element (18) facing the sensor environment (20) and affecting the measurement signal (16). Compensation (24) is performed by the method (26) for compensation as described in claim 8.

10. A pressure sensor (14) that provides a measurement signal (16) by means of a sensor element (18) based on the deflection of the sensor element (18) in relation to the pressure (p) on the pressure sensor (14), and the pressure sensor has an insulating material on the sensor element (18) for protection against environmental influences, and the pressure sensor is configured to operate by means of the method for operation (10) according to claim 9.

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