Sensor device

Abstract

A sensor device (1) designed to measure pressure (P). [Solution] The sensor device (1) comprises at least one substrate (10) and at least one sensor material (20). The substrate (10) is formed as a substrate diaphragm (11) within several areas. The substrate diaphragm (11) has a thickness (T11) along a vertical axis (Z) and a diameter (D11) in a horizontal plane (XY) perpendicular to the vertical axis (Z). The substrate diaphragm (11) is designed to detect a pressure (P) to be measured and can bend along the vertical axis (Z) under the action of the pressure (P). The sensor material (20) is placed on the substrate diaphragm (11). It generates piezoelectric charges (Q20+, Q20-) under the action of the bending of the substrate diaphragm (11), and the amount of piezoelectric charges (Q20+, Q20-) generated is proportional to the magnitude of the measured pressure (P).

Description

[Technical Field]

[0001] The present invention relates to a sensor device according to the preamble of an independent claim. [Background technology]

[0002] Sensor devices are well known. They are used in a variety of applications to measure pressure, temperature, and other parameters.

[0003] Thus, sensor devices that measure pressure according to the piezoelectric principle are known. For this purpose, they are equipped with piezoelectric materials such as quartz (SiO2) and gallium orthophosphate (GaPO4) that generate a piezoelectric charge under the action of the pressure to be measured. The piezoelectric charge is generated on the surface of the piezoelectric material and extracted by electrodes. The amount of piezoelectric charge generated is proportional to the magnitude of the measured pressure.

[0004] Piezoelectric materials such as SiO2 and GaPO4 exhibit extremely high external rigidity. This high external rigidity allows piezoelectric sensor devices to have a high natural frequency exceeding 500 kHz. This high natural frequency makes piezoelectric sensor devices suitable for dynamic pressure measurement. Generally, the maximum measurement frequency is one-third of the natural frequency.

[0005] Such a piezoelectric sensor device for dynamic pressure measurement is sold by the applicant as type 603C. In type 603C, piezoelectric material formed as multiple discs is axially spaced from a diaphragm by a base plate. The pressure to be measured acts as a force on the piezoelectric material through the diaphragm and the base plate. Since piezoelectric materials such as SiO2 and GaPO4 are brittle and can break at local pressure peaks, the base plate ensures that the pressure distribution on the piezoelectric material is uniform. The maximum measurement frequency of type 603C is approximately 200 kHz. The technical specifications for type 603C are described in datasheet No. 603C_003-288e-11.22.

[0006] Currently, users of pressure measurement sensor devices are seeking to further increase the measurement frequency.

[0007] The object of the present invention is to provide a sensor device that exhibits a measurement frequency significantly higher than 200 kHz in pressure measurement. [Overview of the project]

[0008] This objective is achieved by the features of the independent claim.

[0009] The present invention relates to a sensor device adapted for measuring pressure, comprising at least one substrate and at least one sensor material, wherein the substrate is formed as a substrate diaphragm in several areas, the substrate diaphragm having a thickness along a vertical axis and a diameter in a horizontal plane perpendicular to the vertical axis, the substrate diaphragm is designed to detect a pressure to be measured, the substrate diaphragm is capable of bending along a vertical axis under the influence of the pressure, the sensor material is placed on the substrate diaphragm and generates a piezoelectric charge due to the bending of the substrate diaphragm, the amount of the generated piezoelectric charge is proportional to the magnitude of the measured pressure, the thickness of the substrate diaphragm is 20 μm or less, preferably 10 μm or less, preferably 5 μm or less, the diameter of the substrate diaphragm is 300 μm or less, preferably 200 μm or less, preferably 100 μm or less, and the ratio of the thickness to the diameter of the substrate diaphragm is selected such that the sensor device has a natural frequency of 1 MHz or higher.

[0010] Preferred embodiments of the present invention are protected by the dependent claims.

[0011] The present invention will be described in more detail below, with reference to the figures. [Brief explanation of the drawing]

[0012] [Figure 1] A partial plan view of a first embodiment of a sensor device 1 equipped with a pressure sensor 1P for measuring pressure P is shown. [Figure 2] FIG. 1 shows a partial cross-sectional view of the sensor device 1 along the A-A cross-section shown in FIG. 1. [Figure 3] FIG. 4 shows a partial plan view of the second embodiment of the sensor device 1 including the group of pressure sensors 1P shown in FIG. 1. [Figure 4] FIG. 7 is a partial schematic circuit diagram of the first embodiment of the sensor device 1 including the pressure sensor 1P according to FIG. 1 or FIG. 2, and including the transmission device 5, the converter unit 6, and the evaluation unit 7. [Figure 5] FIG. 10 is a partial schematic circuit diagram of the second embodiment of the sensor device 1 including the group of pressure sensors 1P according to FIG. 3, and including the transmission device 5, the converter unit 6, and the evaluation unit 7.

DETAILED DESCRIPTION OF THE INVENTION

[0013] In the figures, the same reference numerals denote the same objects.

[0014] The sensor device 1 has a function of measuring the pressure P.

[0015] As shown in the embodiments of FIGS. 1 to 3, the sensor device 1 includes at least one pressure sensor 1P for measuring the pressure P.

[0016] Furthermore, as shown in FIGS. 4 and 5, the sensor device 1 includes at least one transmission device 5, at least one converter unit 6, and at least one evaluation unit 7.

[0017] In FIGS. 1 to 3, the sensor device 1 is shown in a three-dimensional coordinate system including the horizontal axis X, the lateral axis Y, and the vertical axis Z. The three axes X, Y, and Z are orthogonal to each other. The horizontal axis X and the lateral axis Y extend in the horizontal plane XY. FIGS. 1 and 3 show the embodiments of the sensor device 1 in a plan view within the horizontal plane XY. FIG. 2 shows a cross-section of the sensor device 1.

[0018] Substrate 10 The sensor device 1 includes at least one substrate 10. The substrate 10 has a function of detecting the pressure P to be measured.

[0019] The substrate 10 is made of an electrically insulating material such as silicon and glass. Silicon has a resistivity of 10 7 Ωm or more at room temperature (20 °C). Glass has a resistivity of 10 11 Ωm or more at 20 °C.

[0020] The substrate 10 has a front side and a back side. On the front side, the substrate 10 forms a support surface. The support surface is located in the horizontal plane XY. The support surface has a size of 3 mm × 3 mm or less, preferably 2 mm × 2 mm or less. On the back side, the substrate 10 forms a substrate opening 12.

[0021] Preferably, the substrate 10 is a silicon-on-insulator (SOI) including the following functional layers. - The support layer 13 is made of silicon and has a thickness in the range of 200 to 500 μm along the vertical axis Z, preferably having a thickness of 400 μm. The support layer 13 has a function of supporting the components of the sensor device 1. - The boundary layer 14 is made of silicon and has a thickness in the range of 100 to 2 μm along the vertical axis Z, preferably having a thickness of 50 μm, and more preferably having a thickness of 5 μm. The boundary layer 14 has a function of forming a substrate diaphragm 11 in several areas. The boundary layer 14 defines the substrate 10 in the horizontal plane XY. - The stop layer 15 has a thickness of 1 μm along the vertical axis Z and is arranged along the vertical axis Z between the support layer 13 and the boundary layer 14. The stop layer 15 is made of an oxide material and has a resistivity of 10 at 20 °C 12It has a resistivity of Ωm or greater. Therefore, the function of the stop layer 15 is to electrically insulate the boundary layer 14 from the support layer 13. Furthermore, the stop layer 15 functions as an etching stop during the manufacturing of substrate openings 12 by chemical etching in the substrate 10. During manufacturing, silicon is etched away along the vertical axis Z on the back side of the substrate 10 up to the stop layer 15.

[0022] The base diaphragm 11 is designed to detect a pressure P to be measured. The base diaphragm 11 comprises two surfaces F11 and F12. The two surfaces F11 and F12 include a front surface F11 and a back surface F12. The front surface F11 is on the front side of the base 10 and is located in the horizontal plane XY. The pressure P acts on the front surface F11 along the vertical axis Z. The front surface F11 is oriented in the direction in which the pressure P acts. The back surface of the base diaphragm 11 defines a base opening 12 on the back side of the base 10. Under the action of the pressure P, the base diaphragm 11 may flex inward into the base opening 12 along the vertical axis Z.

[0023] The base diaphragm 11 has a thickness T11 of 20 μm or less, preferably 10 μm or less, and preferably 5 μm or less. The base diaphragm 11 has a diameter D11 of 300 μm or less, preferably 200 μm or less, and preferably 100 μm or less. The ratio of the thickness T11 to the diameter D11 of the base diaphragm 11 is selected so that the sensor device 1 has a natural frequency f1 of 1 MHz or higher. Advantageously, the ratio of the thickness T11 to the diameter D11 of the base diaphragm 11 is 1.7. -2 ~5.0 10 -2 It is within the range. The exemplary ratio of the thickness T11 to the diameter D11 of the base diaphragm 11 results in the following natural frequency f1. - If the thickness T11 of the base diaphragm 11 is equal to 5 μm and the diameter D11 of the base diaphragm 11 is equal to 300 μm, the resulting ratio of the thickness T11 to the diameter D11 of the base diaphragm 11 is 1.7 10 -2 This is equivalent to a natural frequency f1 exceeding 1 MHz. - When the thickness T11 of the base diaphragm 11 is equal to 5 μm and the diameter D11 of the base diaphragm 11 is equal to 200 μm, the ratio obtained as a result of the thickness T11 with respect to the diameter D11 of the base diaphragm 11 is 2.5×10 -2 equals, and the resulting natural frequency f1 exceeds 2.5 MHz. - When the thickness T11 of the base diaphragm 11 is equal to 5 μm and the diameter D11 of the base diaphragm 11 is equal to 100 μm, the ratio obtained as a result of the thickness T11 with respect to the diameter D11 of the base diaphragm 11 is 5.0×10 -2 equals, and the resulting natural frequency f1 exceeds 10 MHz.

[0024] In contrast to the 603C type piezoelectric sensor device provided with a metal diaphragm made of stainless steel 17 - 4PH, the base diaphragm 11 according to the present invention is made of silicon. 7.8 g / cm 3 Compared with stainless steel 17 - 4PH having a density of, silicon has a density of 2.3 g / cm 3 . Therefore, the base diaphragm 11 according to the present invention is more than three times lighter, thereby further increasing the natural frequency f1 of the sensor device 1.

[0025] Sensor material 20 The sensor device 1 includes at least one sensor material 20. The sensor material 20 has a function of generating a measured value of the pressure P to be measured.

[0026] The sensor material 20 is piezoelectric and is composed of quartz (SiO2), gallium orthophosphate (GaPO4), calcium gallogermanate (Ca3Ga2Ge4O 14 , that is, CGG), langasite (La3Ga5SiO 14 , that is, LGS), tourmaline, aluminum nitride (AlN), lead zirconate titanate (PZT), aluminum scandium nitride (Al(1 - x)Sc(x)N where x = 0...0.4), and potassium sodium niobate (K(x)Na(1 - x)NbO3 where x = 0.2...0.5), etc.

[0027] The sensor material 20 is placed on the substrate 10. Preferably, the sensor material 20 is placed on the front side of the substrate 10 within at least one area of ​​the substrate diaphragm 11.

[0028] Preferably, the sensor material 20 is arranged within several areas on the front surface F11 of the base diaphragm 11. The sensor material 20 forms a layer extending in the horizontal plane XY. Within the horizontal plane XY, the sensor material 20 has a base area D20. The base area D20 is greater than or equal to the diameter D11 of the base diaphragm 11. The sensor material 20 has a constant thickness T20 along the vertical axis Z. The thickness T20 is 10 μm or less, preferably 5 μm or less, and preferably 1 μm or less.

[0029] The 603C type piezoelectric sensor device comprises sensor material in the form of three discs, each having a thickness of 0.2 mm and a diameter of 3.5 mm. Viewed axially, the discs are separated from the diaphragm by a metal base plate having a thickness of 0.6 mm and a diameter of 3.5 mm. In contrast to the 603 type piezoelectric sensor device, the sensor material 20 is arranged as a thin layer on the substrate diaphragm 11 according to the present invention. The thickness T20 of the thin layer is 10 μm or less. This means that the weight of the sensor device 1 according to the present invention is reduced because there are no sensor material discs and no metal base plate. Furthermore, since the natural frequency f1 is inversely proportional to the weight of the sensor device 1, the natural frequency f1 of the sensor device 1 increases due to the absence of sensor material discs and a metal base plate.

[0030] Under the action of the pressure P to be measured, the sensor material 20 generates piezoelectric charges Q20+ and Q20- as measured values. The pressure P acts in one direction along the vertical axis Z on the front surface F11 of the substrate diaphragm 11, causing the substrate diaphragm 11 to flex. In Figure 2, the pressure P is schematically shown as an arrow. The piezoelectric material 20 generates piezoelectric charges Q20+ and Q20- as a result of the flexing of the substrate diaphragm 11. The amount of piezoelectric charges Q20+ and Q20- generated is proportional to the magnitude of the measured pressure P. The sustained operating temperature of the sensor material 20 is in the range of -40°C to +500°C.

[0031] Piezoelectric charges Q20+ and Q20- are generated on multiple surfaces of the sensor material 20, which are surfaces parallel to the horizontal plane XY. The piezoelectric charges Q20+ and Q20- include a first piezoelectric charge Q20+ and a second piezoelectric charge Q20-. In the cross-section shown in Figure 2, the first piezoelectric charge Q20+ is generated on the surface of the sensor material 20 facing away from the substrate diaphragm 11, and the second piezoelectric charge Q20- is generated on the surface of the sensor material 20 facing the substrate diaphragm 11. In the following description, the first piezoelectric charge Q20+ is preferably converted into a pressure signal PS, while the second piezoelectric charge Q20- is preferably used as a ground potential signal MS.

[0032] The sensitivity σ of the sensor device 1 is extremely important. Sensitivity σ is the ratio of the measured value to the input value of the pressure P to be measured. Sensitivity σ decreases on the order of the cube with increasing thickness T11 of the base diaphragm 11. Furthermore, sensitivity σ decreases on the order of the square with decreasing diameter D11 of the base diaphragm 11. Therefore, the sensitivity σ of the sensor device 1 decreases with increasing ratio of thickness T11 to diameter D11 of the base diaphragm 11. - The thickness T11 of the base diaphragm 11 is equal to 5 μm, the diameter D11 of the base diaphragm 11 is equal to 300 μm, and the resulting ratio of the thickness T11 to the diameter D11 of the base diaphragm 11 is 1.7 10 -2 If equal to , the resulting sensitivity σ of sensor device 1 when AlN is used as the sensor material is approximately 5 pC / bar. - The thickness T11 of the base diaphragm 11 is equal to 5 μm, the diameter D11 of the base diaphragm 11 is equal to 200 μm, and the resulting ratio of the thickness T11 to the diameter D11 of the base diaphragm 11 is 2.5 10 -2 If equal to this, the resulting sensitivity σ of sensor device 1 when AlN is used as the sensor material is approximately 0.5 pC / bar. - The thickness T11 of the substrate diaphragm 11 is equal to 5 μm, the diameter D11 of the substrate diaphragm 11 is equal to 100 μm, and the resulting ratio of the thickness T11 to the diameter D11 of the substrate diaphragm 11 is 5.0 10 -2 If equal to , the resulting sensitivity σ of sensor device 1 when AlN is used as the sensor material is approximately 0.05 pC / bar.

[0033] Pressure sensor 1P The sensor device 1 comprises a plurality of sensor electrodes 21 and 23. The sensor electrodes 21 and 23 have the function of extracting piezoelectric charges Q20+ and Q20- from the surface of the sensor material 20.

[0034] The sensor electrodes 21 and 23 are positioned within a region of the surface of the sensor material 20 where piezoelectric charges Q20+ and Q20- are generated. The sensor electrodes 21 and 23 include a first sensor electrode 21 and a second sensor electrode 23. The sensor electrodes 21 and 23 are made of conductive materials such as silver (Ag), gold (Au), and platinum (Pt).

[0035] In the cross-section shown in Figure 2, the first sensor electrode 21 is positioned on the surface of the sensor material 20 facing away from the substrate diaphragm 11, and extracts a first piezoelectric charge Q20+. The second sensor electrode 23 is positioned on the surface of the sensor material 20 facing the substrate diaphragm 11, and extracts a second piezoelectric charge Q20-. Each of the two sensor electrodes 21 and 23 forms a layer extending parallel to the horizontal plane XY. Parallel to the horizontal plane XY, the first sensor electrode 21 has a first sensor base area D21, and the second sensor electrode 23 has a second sensor base area D23. Along the vertical axis Z, each of the two sensor electrodes 21 and 23 has a constant thickness of 200 nm or less.

[0036] Compared to a 603C type piezoelectric sensor device having a diaphragm with a diameter of 5.5 mm, the base diaphragm 11 according to the present invention is about an order of magnitude smaller. The base diaphragm 11 is miniaturized. The surface of a 603C type diaphragm has space to accommodate more than 100 base diaphragms 11 according to the present invention. The base diaphragm 11, the sensor material 20 placed thereon, and the sensor electrodes 21, 23 placed on the surface of the sensor material 20 form a miniaturized pressure sensor 1P, which not only generates piezoelectric charges Q20+, Q20- in response to the pressure P to be measured, but also includes sensor electrodes 21, 23 for extracting these piezoelectric charges Q20+, Q20- from the surface of the sensor material 20.

[0037] The external rigidity of the base diaphragm 11 is not constant across its entire diameter D11. While the external rigidity is constant along the vertical Z in the central area of ​​the base diaphragm 11, it increases in the peripheral area of ​​the transition between the stop layer 15 and the support layer 13. However, an increase in external rigidity in the peripheral region of the base diaphragm 11 reduces the sensitivity σ of the sensor device 1, and therefore the generation of piezoelectric charges Q20+ and Q20-. This decrease in the sensitivity σ of the sensor device 1 in the peripheral area of ​​the base diaphragm 11 distorts the measured pressure P. It is preferable that the first piezoelectric charge Q20+ is not extracted at all in the peripheral area, and that this first piezoelectric charge Q20+ is preferentially used as the pressure signal PS, thereby avoiding a decrease in the sensitivity σ of the sensor device 1 in the peripheral area of ​​the base diaphragm 11. For this reason, the diameter of the first sensor base area D21 from which the first piezoelectric charge Q20+ is extracted is smaller than the diameter D11 of the substrate diaphragm 11. Preferably, the first sensor base area D21 is 80% or less, and more preferably 60% or less, of the diameter D11 of the substrate diaphragm 11.

[0038] On the other hand, the second sensor base area D23 from which the second piezoelectric charge Q20- is extracted is preferably greater than or equal to the diameter D11 of the substrate diaphragm 11, and the second piezoelectric charge Q20- is preferably used as a ground potential signal MS.

[0039] The sensor device 1 includes a plurality of sensor contacts 22 and 24. These sensor contacts 22 and 24 have the function of providing electrical contacts between the sensor electrodes 21 and 23 and the transmission device 5.

[0040] The sensor contacts 22 and 24 are made of conductive materials such as Ag, Au, and Pt.

[0041] The sensor contacts 22 and 24 include a first sensor contact 22 and a second sensor contact 24. The first sensor contact 22 is positioned on the first sensor electrode 21 and forms an electrical contact with the first sensor electrode 21. The second sensor contact 24 is positioned on the second sensor electrode 23 and forms an electrical contact with the second sensor electrode 23. Each of the two sensor contacts 22 and 24 has a planar extension parallel to the horizontal plane XY, and this planar extension is designed to be large enough to realize an electrical contact by ultrasonic thermal ball-wedge bonding and ultrasonic wedge-wedge bonding, etc.

[0042] The base diaphragm 11, the sensor material 20 placed on the front surface F11 of the base diaphragm 11, and the sensor electrodes 21 and 23 placed on the surface of the sensor material 20 form the pressure sensor 1P of the embodiment of the sensor device 1 shown in Figures 1 to 3. The piezoelectric charges Q20+ and Q20- are measured values ​​of the pressure sensor 1P. The continuous operating temperature of the pressure sensor 1P is in the range of -40°C to +500°C.

[0043] Group of pressure sensors 1P According to a second embodiment of the sensor device 1, the base body 10 comprises a plurality of base body diaphragms 11.

[0044] The multiple substrate diaphragms 11 are preferably arranged on the surface of a substrate 10 lying in a horizontal plane XY. The pressure P to be measured acts on the front surface F11 of the multiple substrate diaphragms 11 along the vertical direction Z, causing the multiple substrate diaphragms 11 to flex. The sensor material 20 is placed on each of the multiple substrate diaphragms 11, in at least one area on the front surface F11 of the substrate diaphragm 11. The sensor material 20 generates piezoelectric charges Q20+ and Q20- due to the flexing of the substrate diaphragms 11. On each of the multiple substrate diaphragms 11, a first sensor electrode 21 is placed on the surface of the sensor material 20 facing away from the substrate diaphragm 11, and extracts a first piezoelectric charge Q20+. A second sensor electrode 23 is placed on the surface of the sensor material 20 facing the substrate diaphragm 11, and extracts a second piezoelectric charge Q20-.

[0045] According to the second embodiment, the sensor device 1 comprises a plurality of sensor group conductors 25, 27. The sensor group conductors 25, 27 function to collect piezoelectric charges Q20+, Q20-.

[0046] The sensor group conductors 25 and 27 are made of conductive materials such as Ag, Au, and Pt.

[0047] The sensor group conductors 25 and 27 are arranged within areas on two surfaces of the sensor material 20. The sensor group conductors 25 and 27 include a first sensor group conductor 25 and a second sensor group conductor 27. The first sensor group conductor 25 forms an electrical contact with the first sensor electrode 21 and electrically connects them in series. The second sensor group conductor 27 forms an electrical contact with the second sensor electrode 23 and electrically connects them in series.

[0048] Multiple base diaphragms 11 on which sensor material 20 is placed on the front surface F11, the sensor material 20 placed on the multiple base diaphragms 11, and sensor electrodes 21, 23 and sensor group conductors 25, 27 placed on the surface of the sensor material 20 form a group of pressure sensors 1P.

[0049] Advantageously, two or more substrate diaphragms 11, preferably 16 or more substrate diaphragms 11, and preferably 128 or more substrate diaphragms 11 are formed on the substrate 10.

[0050] An increase in the natural frequency f1 in the sensor device 1 according to the present invention is achieved by reducing the ratio of the thickness T11 to the diameter D11 of the base diaphragm 11; however, this also reduces the sensitivity σ of the sensor device 1 according to the present invention. The sensitivity σ changes on the order of the square of the diameter D11 of the base diaphragm 11. If the thickness T11 is kept constant, halving the diameter D11 of the base diaphragm 11 reduces the amount of piezoelectric charges Q20+ and Q20- generated to 1 / 4. By arranging multiple base diaphragms 11 within the base 10, placing the sensor material 20 on each of the front surfaces F11 of the multiple base diaphragms 11, and further connecting sensor electrodes 21 and 23 in series to extract the piezoelectric charges Q20+ and Q20- from the sensor material 20, the decrease in sensitivity σ of the sensor device 1 according to the present invention can be offset, and may even be increased.

[0051] According to the second embodiment, the sensor device 1 includes a plurality of sensor group contacts 26, 28. The sensor group contacts 26, 28 function to provide electrical contacts to the transmission device 5.

[0052] The sensor group contacts 26 and 28 are made of conductive materials such as Ag, Au, and Pt.

[0053] The sensor group contacts 26 and 28 include a first sensor group contact 26 and a second sensor group contact 28. The first sensor group contact 26 is positioned on the first sensor group conductor 25 and forms an electrical contact with the first sensor group conductor 25. The second sensor group contact 28 is positioned on the second sensor group conductor 27 and forms an electrical contact with the second sensor group conductor 27. Each of the two sensor group contacts 26 and 28 has a planar extension parallel to the horizontal plane XY, and this planar extension is sized to be large enough to realize an electrical contact by ultrasonic thermal ball wedge bonding and ultrasonic wedge-wedge bonding, etc.

[0054] Transmission device 5 The transmission device 5 has the function of transmitting piezoelectric charges Q20+ and Q20-.

[0055] The transmission device 5 comprises a plurality of charge carriers 51, 52 made of conductive materials such as copper (Cu), silver (Ag), and gold (Au). The charge carriers 51, 52 are wires, typically with a diameter of 15 to 200 μm.

[0056] The charge carriers 51 and 52 include a first charge carrier 51 and a second charge carrier 52.

[0057] As shown in the schematic circuit diagram of Figure 4, an electrical contact is formed between the first sensor contact 22 and the first charge transmission body 51, and an electrical contact is formed between the second sensor contact 24 and the second charge transmission body 52. ​​Piezoelectric charges Q20+ and Q20- are transmitted from the sensor contacts 22 and 24 by these charge transmission bodies 51 and 52.

[0058] As shown in the schematic circuit diagram of Figure 5, an electrical contact is formed between the first sensor group contact 26 and the first charge transmission body 51, and an electrical contact is formed between the second sensor group contact 28 and the second charge transmission body 52. ​​Piezoelectric charges Q20+ and Q20- are transmitted from the two sensor group contacts 26 and 28 by these charge transmission bodies 51 and 52.

[0059] When the measurement frequency f* significantly exceeds 100 kHz, the wave impedance Z5 of the transmission device 5 must be considered. This is because the piezoelectric charges Q20+ and Q20- of the charge carriers 51 and 52 generate a magnetic field, thereby creating inductance. Furthermore, the charge carriers 51 and 52 form capacitance relative to each other. The wave impedance Z5 depends on both the inductance and capacitance of the transmission device 5. The wave impedance Z5 causes electromagnetic waves to be reflected at the ends of the transmission device 5. Reflection of electromagnetic waves can distort the pressure measurement. To avoid such reflections, at least one end of the transmission device 5 is electrically terminated by an electrical resistor. The electrical resistor absorbs the incident electromagnetic waves. This electrical resistance is equal to the wave impedance Z5 of the transmission device 5. According to industry standards, for coaxial cable transmission equipment 5, the wave impedance Z5 is 50Ω or 75Ω, and for two-wire transmission equipment 5, the wave impedance Z5 is in the range of 100Ω to 300Ω.

[0060] Converter unit 6 The converter unit 6 functions to electrically convert the transmitted piezoelectric charges Q20+ and Q20- into at least one measurement signal PS, MS.

[0061] The measured signals PS and MS include the pressure signal PS and the ground potential signal MS. The pressure signal PS corresponds to the first piezoelectric charge Q20+. The ground potential signal MS corresponds to the second piezoelectric charge Q20-.

[0062] As shown in the schematic circuit diagrams of Figures 4 and 5, the converter unit 6 comprises at least one operational amplifier 61, at least one feedback capacitance 62, at least one first charge input contact 63, at least one second charge input contact 65, at least one signal output contact 66, and at least one ground potential output contact 67.

[0063] The operational amplifier 61 includes an inverting input i-, a non-inverting input i+, and a signal output o. The inverting input i- is 10 -14High electrical insulation is provided by a small leakage current of less than A (amperes). The inverting input i- of the converter unit 6 has an input impedance Z61 close to 0Ω. The non-inverting input i+ is connected to the ground potential 64 of the sensor device 1. The ground potential 64 is an electrical reference potential such as 0V. The ground potential 64 may be the potential of the conductive ground at the installation location of the sensor device 1.

[0064] The charge input contacts 63 and 65 have the function of providing electrical contacts between the converter unit 6 and the transmission device 5. The charge input contacts 63 and 65 are made of conductive materials such as Cu, Ag, and Au.

[0065] The first charge transmitter 51 is one end of the transmission device 5 to the inverting input i- of the operational amplifier 61. The first charge transmitter 51 is in electrical contact with the inverting input i- of the operational amplifier 61 via the first charge input contact 63. As a result, the second piezoelectric charge Q20+ from the pressure sensor 1P and the group of pressure sensors 1P is applied to the inverting input i- of the operational amplifier 61. The second piezoelectric charge Q20+ generates a current at the inverting input i-.

[0066] The second charge transmission body 52 is in electrical contact with the ground potential 64 via the second charge input contact 65. As a result, the first piezoelectric charge Q20- of the pressure sensor 1P and the group of pressure sensors 1P is brought to the ground potential 64.

[0067] The operational amplifier 61 functions to amplify the piezoelectric charge Q20+ at the inverting input i-.

[0068] The operational amplifier 61 operates to reduce the voltage difference between the inverting input i- and the non-inverting input i+ to zero. To this end, the piezoelectric charge Q20+ to be amplified flows from the inverting input i- into the operational amplifier 61 as a current, generating an electrical output voltage at the signal output o.

[0069] The operational amplifier 61 has an operating frequency f61. The operating frequency f61 is the highest frequency at which the operational amplifier 61 can amplify the piezoelectric charge Q20+. Preferably, the operating frequency f61 is 50 MHz or higher, and more preferably 500 MHz or higher.

[0070] The feedback capacitance 62 is connected in parallel to the inverting input i- and signal output o of the operational amplifier 61.

[0071] The feedback capacitance 62 functions to adjust the amplification factor of the converter unit 6. The feedback capacitance 62 is connected between the inverting input i- and the signal output o of the operational amplifier 61. Through the feedback capacitance, the electrical output voltage applied to the signal output o flows back to the inverting input i- as a current 62. The amount of current that flows back depends on the magnitude C62 of the feedback capacitance 62. The larger the feedback capacitance 62, the more current flows back to the inverting input i-, where it then flows into the operational amplifier 61 in addition to the piezoelectric charge Q20+ that is to be amplified. Preferably, the magnitude C62 of the feedback capacitance 62 is in the range of 10pF to 1000pF.

[0072] The input impedance Z61 at the inverting input i- is inversely proportional to the product of the operating frequency f61 of the operational amplifier 61 and the magnitude C62 of the feedback capacitance 62:

number

[0073] To avoid reflection of electromagnetic waves within the transmission device 5 and at the inverting input i-, the wave impedance Z5 of the transmission device 5 is matched with the input impedance Z61 at the inverting input i-. For this purpose, a balanced impedance Z6 is electrically connected between one end of the transmission device 5 facing the inverting input i- and the inverting input i-. The following is applied to adjusting the wave impedance Z5 of the transmission device 5: Z5 = Z61 + Z6

[0074] The balanced impedance Z6 is approximately the same magnitude as the wave impedance Z5 of the transmission device 5. Preferably, the balanced impedance Z6 is less than or equal to the wave impedance Z5 of the transmission device 5. If the wave impedance Z5 of the transmission device 5 is designed as a 50Ω or 75Ω coaxial cable, the balanced impedance Z6 is less than or equal to this wave impedance Z5 of the 50Ω or 75Ω coaxial cable. If the wave impedance Z5 of the transmission device 5 is designed as a two-wire system in the range of 100Ω to 300Ω, the balanced impedance Z6 is less than or equal to this wave impedance Z5 of the two-wire system in the range of 100Ω to 300Ω. Preferably, the balanced impedance Z6 is 300Ω or less, preferably 75Ω or less, and preferably 50Ω or less.

[0075] A numerical example is shown below. If the proportionality constant between the input impedance Z61 at the inverting input i- and the product of the operating frequency f61 of the operational amplifier 61 and the magnitude C62 of the feedback capacitance 62 is 2π, and the operating frequency f61 of the operational amplifier 61 is 500MHz and the magnitude C62 of the feedback capacitance 62 is 100pF, then the input impedance Z61 at the inverting input i- is 3.2Ω. When this is matched with the wave impedance Z5 of the transmission device 5, which is designed as a 50Ω coaxial cable, the balanced impedance Z6 becomes 46.8Ω.

[0076] The pressure signal PS is the electrical output voltage applied to the signal output o of the operational amplifier 61. The pressure signal PS corresponds to the amount of the first piezoelectric charge Q20+. The converter unit 6 amplifies each first piezoelectric charge Q20+ to give the pressure signal PS.

[0077] The signal output contact 66 and the ground potential output contact 67 function to provide electrical contacts between the converter unit 6 and the evaluation unit 7. The signal output contact 66 and the ground potential output contact 67 are made of conductive materials such as Cu, Ag, and Au.

[0078] The signal output o of the operational amplifier 61 forms an electrical contact with the signal output contact 66. The pressure signal PS is applied to the signal output contact 66. The ground potential output contact 67 forms an electrical contact with the ground potential 64. The ground potential signal MS is applied to the ground potential output contact 67.

[0079] Evaluation Unit 7 The evaluation unit 7 has the function of evaluating the sensor signals PS and MS.

[0080] For this purpose, the evaluation unit 7 comprises at least one signal conductor 71, at least one ground potential conductor 72, at least one interface 73, at least one arithmetic unit 74, at least one input unit 75, and at least one output unit 76.

[0081] The signal conductor 71 and the ground potential conductor 72 are made of conductive materials such as Cu, Ag, and Au.

[0082] An electrical contact with the signal conductor 71 is formed at the first signal output contact 66, and an electrical contact with the ground potential conductor 72 is formed at the first ground potential output contact 72. The pressure signal PS is transmitted to the interface 73 via the signal conductor 71. The ground potential signal MS is supplied to the interface 73 via the ground potential conductor 72.

[0083] Interface 73 has the function of digitizing the measurement signals PS and MS and providing measurement data elements PD and MD.

[0084] For this purpose, the interface 73 comprises at least one converter element, such as an analog-to-digital converter. The converter element is configured to digitize the measurement signals PS and MS to give measurement data elements PD and MD. Each measurement data element PD and MD specifies the measurement data quantities pv and mv for the measured value. Each measurement data element PD and MD is a binary sequence having a resolution such as 12 bits and 16 bits.

[0085] Interface 73 also includes at least one timer, such as a clock. This timer is configured to assign time points pt and mt to each measurement data element PD and MD. Each time point pt and mt is a binary sequence with a resolution such as 12 bits and 16 bits. The time points pt and mt assigned to the measurement data elements PD and MD are also hereafter referred to as the time points pt and mt associated with the measurement data elements PD and MD. In time points pt and mt, Interface 73 digitizes the sensor signals PS and MS into the measurement data elements PD and MD. Time points pt and mt have a time resolution, which, according to the Nyquist-Shannon sampling theorem, is equal to the reciprocal value of twice the measurement frequency f*. For measurement frequencies f* at most 1 / 3 of a natural frequency f1 of 1 MHz or more, time points pt and mt are 3 / 2 10 -6 It has a time resolution of more than a second.

[0086] The measurement data elements PD and MD include at least one pressure data element PD having a pressure quantity pv, and the time points pt and mt include at least one pressure time point pt associated with the pressure data element PD. Interface 73 digitizes each pressure signal PS to provide a pressure data element PD having a pressure quantity pv and a pressure data element PD having an associated pressure time point pt.

[0087] As shown in the schematic diagrams of Figures 4 and 5, the measurement data elements PD and MD also include at least one ground potential data element MD having a ground potential quantity mv, and the time points pt and mt include at least one ground potential time point mt associated with the ground potential data element MD.

[0088] The arithmetic unit 74 includes at least one data memory and at least one data processor.

[0089] The arithmetic unit 74 includes at least one evaluation program AP stored in data memory that can be loaded into the data processor. The evaluation program AP loaded into the data processor is configured to evaluate measurement data elements PD, MD having measurement data quantities pv, mv and time points pt, mt.

[0090] The arithmetic unit 74 can be operated by the input unit 75. The verb "operate" means that a human can input a command using the input unit 75, and that command is then executed by the arithmetic unit 75. The input unit 75 may be a keyboard or a touchscreen for command input. A command may be entered as a string by the input unit 75, and the evaluation program AP loaded into the data processor is configured to generate control data for the entered command. Thus, the entered command may be for switching the sensor device 1 on or off, and the evaluation program AP loaded into the data processor is configured to generate control data for the command, which switches the sensor device 1 on or off.

[0091] Furthermore, the evaluation program AP loaded into the data processor is also configured to graphically display the measurement data elements PD, MD and date element t for evaluation. The output unit 76 may be a screen on which the measurement data elements PD and MD are graphically displayed for human use.

[0092] Those skilled in the art familiar with the present invention can implement various modifications of the presented embodiments. For example, the pressure sensor 1P, the transmission device 5, and the converter unit 6 may be mounted in a housing at the installation location where the pressure P is measured. [Explanation of Symbols]

[0093] 1. Sensor device 1P Pressure Sensor 5. Transmission device 6 Converter Units 7 Evaluation Units 10 Base 11 Base diaphragm D11 Diameter of the base diaphragm F11 Front surface of the base diaphragm F12 Back surface of the base diaphragm T11 Thickness of the base diaphragm 12 Base opening 13 Support layer 14 Boundary layer 15 Stop Layer 20 Sensor Materials D20 Sensor material base area T20 Sensor material thickness 21 First recovery electrode D21 Base area of ​​the first sensor electrode 22 First sensor contact 23 Second sensor electrode D23 Base area of ​​the second sensor electrode 24 Second sensor contact 25 First sensor group conductor 26 First sensor group contact 27 Second sensor group conductor 28 Second sensor group contact 51 First charge carrier 52 Second charge carrier 61 Operational Amplifier - Inverted input +Non-inverted input o Signal output 62 Feedback Capacitance C62 Feedback capacitance magnitude 63 First charge input contact 64. Ground potential 65 Second charge input contact 66 Signal output contact 67 Ground potential output contact 71 Signal Conductor 72 Ground potential conductor 73 Interface 74 arithmetic units 75 Input Units 76 Output Units AP Evaluation Program AA section path f1 Natural frequency f* measurement frequency f61 Operating frequency MD Ground Potential Data Element MS ground potential signal mt Ground potential point mv ground potential amount P pressure PD pressure data elements PS pressure signal pt pressure point pv pressure Q20+ First piezoelectric charge Q20 - Second piezoelectric charge σ Sensitivity X horizontal axis XY horizontal plane Y horizontal axis Z vertical axis Z5 Wave Impedance Z6 Balanced Impedance Z61 Input Impedance

Claims

1. A sensor device (1) designed to measure pressure (P), comprising at least one substrate (10) and at least one sensor material (20), wherein the substrate (10) is formed as a substrate diaphragm (11) in several areas, the substrate diaphragm (11) having a thickness (T11) along a vertical axis (Z) and a diameter (D11) in a horizontal plane (XY) perpendicular to the vertical axis (Z), the substrate diaphragm (11) is designed to detect the pressure (P) to be measured, and the substrate diaphragm (11) is capable of bending along the vertical axis (Z) under the action of the pressure (P), wherein the sensor material (20) is the substrate diaphragm The sensor material (20) is positioned on (11) and generates piezoelectric charges (Q20+, Q20-) due to the deflection of the base diaphragm (11), the amount of the generated piezoelectric charges (Q20+, Q20-) is proportional to the magnitude of the measured pressure (P), the thickness (T11) of the base diaphragm (11) is 20 μm or less, preferably 10 μm or less, preferably 5 μm or less, the diameter (D11) of the base diaphragm (11) is 300 μm or less, preferably 200 μm or less, preferably 100 μm or less, and the ratio of the thickness (T11) to the diameter (D11) of the base diaphragm (11) is selected such that the sensor device (1) has a natural frequency (f1) of 1 MHz or higher. A sensor device (1) characterized by the following.

2. The ratio of the thickness (T11) to the diameter (D11) of the base diaphragm (11) is 1.

7. －２ ~5.0 10 －２ The sensor device (1) according to claim 1, characterized in that it is within the range.

3. The sensor device (1) according to claim 1 or 2, characterized in that the sensor material (20) is arranged on the front surface (F11) of the base diaphragm (11), and the front surface (F11) faces the direction in which the pressure (P) acts.

4. The sensor device (1) according to any one of claims 1 to 3, characterized in that the sensor material (20) has a thickness (T20) of 10 μm or less, preferably 5 μm or less, and preferably 1 μm or less, along the vertical axis (Z).

5. The sensor device (1) according to any one of claims 1 to 4, characterized in that the substrate (10) and the substrate diaphragm (11) are made of silicon.

6. The piezoelectric charges (Q20+, Q20-) are generated on a plurality of surfaces of the sensor material (20), the sensor device (1) comprises a plurality of sensor electrodes (21, 23), the sensor electrodes (21, 23) are arranged on the surface of the sensor material (20), and the piezoelectric charges (Q20+, Q20-) are extracted, and the substrate diaphragm (11), the sensor material (20) arranged on the front surface (F11) of the substrate diaphragm (11), and the sensor electrodes (21, 23) arranged on the surface of the sensor material (20) form a pressure sensor (1P), as described in any one of claims 1 to 5.

7. The sensor device (1) according to claim 5, characterized in that the piezoelectric charge (Q20+, Q20-) includes a first piezoelectric charge (Q20+) and a second piezoelectric charge (Q20-), and the plurality of sensor electrodes (21, 23) include a first sensor electrode (21) and a second sensor electrode (23), the first sensor electrode (21) has a first sensor base area (D21), the second sensor electrode (23) has a second sensor base area (D23), the first sensor electrode (21) extracts the first piezoelectric charge (Q20+), the first piezoelectric charge (Q20+) is used as a pressure signal (PS), and the first sensor base area (D23) is 80% or less, preferably 60% or less, of the diameter (D11) of the substrate diaphragm (11).

8. A sensor device (1) according to claim 6 or 7, characterized in that a plurality of substrate diaphragms (11) are formed in several areas within the substrate (10), each of the plurality of substrate diaphragms (11) is designed to receive the pressure (P) to be measured, each of the plurality of substrate diaphragms (11) is capable of bending under the influence of the pressure (P), a sensor material (20) is placed on each of the plurality of substrate diaphragms (11), and the sensor material (20) generates piezoelectric charges (Q20+, Q20-) as a result of the bending of the substrate diaphragm (11).

9. The sensor device (1) according to claim 8, characterized in that two or more substrate diaphragms (11), preferably 16 or more substrate diaphragms (11), preferably 128 or more substrate diaphragms (11), are formed within the substrate (10).

10. The piezoelectric charge (Q20+, Q20-) includes a first piezoelectric charge (Q20+) and a second piezoelectric charge (Q20-), wherein the first piezoelectric charge (Q20+) is generated on the surface of the sensor material (20) facing away from the substrate diaphragm (11), and the second piezoelectric charge (Q20-) is generated on the surface of the sensor material (20) facing the substrate diaphragm (11), and the plurality of sensor electrodes (21, 23) include a first sensor electrode (21) and a second sensor electrode (23), wherein the first sensor electrode (21) is arranged on the surface of the sensor material (20) facing away from the substrate diaphragm (11). The sensor device (1) according to claim 8 or 9, characterized in that a first piezoelectric charge (Q20+) is extracted, the second sensor electrode (23) is arranged on the surface of the sensor material (20) facing the substrate diaphragm (11), a second piezoelectric charge (Q20-) is extracted, and the sensor group conductor (25, 27) includes a first sensor group conductor (25) and a second sensor group conductor (27), the first sensor group conductor (25) electrically connects the first sensor electrode (21) in series, and the second sensor electrode (23) is electrically connected in series by the second sensor group conductor (27).

11. The sensor device (1) according to any one of claims 1 to 10, characterized in that the sensor device (1) comprises at least one transmission device (5), the transmission device (5) comprises a plurality of charge transmission bodies (51, 52), the charge transmission bodies (51, 52) transmit the piezoelectric charge (Q20+, Q20-), and at least one end of the transmission device (5) is electrically terminated by a wave impedance (Z5).

12. The sensor device (1) according to claim 11, wherein the sensor device (1) comprises at least one converter unit (6), the converter unit (6) comprises an operational amplifier (61) and a feedback capacitance (62), the operational amplifier (61) includes an inverting input (i-), a non-inverting input (i+), and a signal output (o), the feedback capacitance (62) is connected between the inverting input (i-) and the signal output (o), the transmission device (5) transmits the piezoelectric charge (Q20+, Q20-) to the converter unit (6), the piezoelectric charge (Q20+, Q20-) includes a first piezoelectric charge (Q20+), the first piezoelectric charge (Q20+) is applied to the inverting input (i-) of the operational amplifier (61), and the converter unit (6) amplifies the first piezoelectric charge (Q20+) into a pressure signal (PS) applied to the signal output (o).

13. The operational amplifier (61) has an operating frequency (f61), and the operational amplifier (61) amplifies the first piezoelectric charge (Q20+) into a pressure signal (PS) according to the operating frequency (f61), the feedback capacitance (62) has a magnitude (C62), the magnitude (C62) determines the amount of current that flows back through the feedback capacitance (62) to the inverting input (i-), the current that flows back amplifies the first piezoelectric charge (Q20+), and the input impedance (Z61) at the inverting input (i-) of the operational amplifier (61) is inversely proportional to the product of the operating frequency (f61) of the operational amplifier (61) and the magnitude (C62) of the feedback capacitance (62): [Math 1] The sensor device (1) according to claim 12, characterized in that

14. The sensor device (1) according to claim 13, characterized in that the input impedance (Z61) at the inverting input (i-) of the operational amplifier (61) is balanced with the wave impedance (Z5) of the transmission device (5) by a balanced impedance (Z6), and the balanced impedance (Z6) is electrically connected between one end of the transmission device (5) that is directed toward the inverting input (i-) of the operational amplifier (61) and the inverting input (i-) of the operational amplifier (61).

15. The sensor device (1) according to claim 14, characterized in that the balanced impedance (Z6) is of a magnitude similar to the wave impedance (Z5) of the transmission device (5).

16. In the case of the wave impedance (Z5) of the transmission device (5) in the embodiment of a 50Ω or 75Ω coaxial cable, the balanced impedance (Z6) is less than or equal to the wave impedance (Z5) of the 50Ω or 75Ω coaxial cable, and in the case of the wave impedance (Z5) of the transmission device (5) in the embodiment of a two-wire system in the range of 100Ω to 300Ω, the balanced impedance (Z6) is less than or equal to the wave impedance (Z5) of this two-wire system in the range of 100Ω to 300Ω, according to claim 15.

17. The sensor device (1) according to any one of claims 13 to 16, characterized in that the operating frequency (f61) of the operational amplifier (61) is 1 / 3 or more of the natural frequency (f1) of the sensor device (1) which is 1 MHz or more.

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