Atmospheric pressure sensor

Abstract

To provide an atmospheric pressure sensor for measuring an atmospheric pressure from a physical quantity different from an elastic displacement.SOLUTION: An atmospheric pressure sensor 100 includes a squeeze film damping structure 8 and a computing unit. The squeeze film damping structure 8 includes a first object 4 and a second object 10 capable of moving relatively to the first object 4. A squeeze film damping phenomenon is generated between the first object 4 and the second object 10. The computing unit calculates an ambient pressure of the squeeze film damping structure 8 from a thermal noise generated in the second object 10.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a barometric pressure sensor. [Background technology]

[0002] Known methods for measuring air pressure include a method for detecting the air pressure itself, a method for utilizing the dependence of other physical quantities (e.g., heat transport amount) on the air pressure, and a method for utilizing the ionization phenomenon of gas. For example, a membrane type barometer is known as a barometer for detecting the air pressure itself. A membrane type barometer is a barometer that measures air pressure from the amount of elastic displacement of a thin film caused by air pressure. As a type of membrane type barometer, a barometer that measures air pressure using the squeeze film damping phenomenon is known (see Non-Patent Document 1). The squeeze film damping phenomenon is a phenomenon in which a resistance force occurs against the movement of the movable plate due to the behavior of a fluid present in the gap region between a fixed plate and a movable plate that are brought close to each other by a distance of several micrometers to several tens of micrometers when the fluid moves along the opposing surfaces of the fixed plate and the movable plate in conjunction with the movement of the movable plate, as the fluid behaves like a viscous fluid. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Aurelien Dantan, "Membrane sandwich squeeze film pressure sensors," Journal of Applied Physics, 128, 091101 (2020); https: / / doi.org / 10.1063 / 5.0011795 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, a membrane-type barometer generally measures air pressure from the amount of elastic displacement of a thin film caused by air pressure, but we disclose an air pressure sensor that measures air pressure from a physical quantity other than the amount of elastic displacement. [Means for solving the problem]

[0005] The technical matters described herein are not intended to explicitly or implicitly limit the invention described in the claims, nor to enable those who benefit from the invention (e.g., the applicant and the right holder) to limit the invention described in the claims, but are merely provided to facilitate understanding of the gist of the invention. The outline of the invention from other perspectives can be understood, for example, from the claims at the time of filing of this patent application. The disclosed air pressure sensor includes a squeeze film damping structure and a calculator. The squeeze film damping structure includes a first object and a second object that is movable relative to the first object. A squeeze film damping phenomenon occurs between the first object and the second object. The calculator calculates the atmospheric pressure of the squeeze film damping structure from thermal noise generated in the second object by the squeeze film damping phenomenon. Effect of the Invention

[0006] According to the air pressure sensor of the present disclosure, it is possible to measure air pressure from thermal noise of a second object that is movable relative to a first object. [Brief description of the drawings]

[0007] [Figure 1] The relationship between the conditions under which the Reynolds equation holds true under the squeeze film damping phenomenon and the atmospheric pressure P. [Diagram 2] The structure of the air pressure sensor. (a) Cross-sectional view. (b) Enlarged view. [Diagram 3] Functional configuration of the air pressure sensor. [Figure 4] Results of the demonstration experiment. [Diagram 5] Functional configuration of the air pressure sensor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Prior to describing embodiments of the air pressure sensor of the present disclosure, the principle of the air pressure sensor of the present disclosure will be described.

[0009] The air pressure sensor disclosed herein includes a squeeze film damping structure. The squeeze film damping structure includes a first object and a second object that is movable relative to the first object. Typically, the first object and the second object each have a flat surface, and the first object and the second object are brought close to each other at a distance of several micrometers to several tens of micrometers, with the flat surface of the first object facing the flat surface of the second object. The thermal noise f (unit: N / √Hz) generated in the second object due to the squeeze film damping phenomenon is expressed by Equation (1) (see Reference 1). In Equation (1), k B is the Boltzmann constant (k B =1.380649×10 -23 [J / K]), T is the ambient temperature of the squeeze film damping structure (i.e., the temperature of the environment in which the squeeze film damping structure is placed) (unit: K), and C SFD is the damping coefficient (unit: N s / m). (Reference 1) TB Gabrielson, "Mechanical-thermal noise in micromachined acoustic and vibration sensors," in IEEE Transactions on Electron Devices, vol. 40, no. 5, pp. 903-909, May 1993, doi: 10.1109 / 16.210197.

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[0010] Damping coefficient C SFDis expressed by equation (2) (see Reference 1). In equation (2), μ is the viscosity of the gas in the gap region between the first and second objects in the squeeze film damping structure (unit: N s / m 2 ), h is the distance between the first and second objects (unit: m), and S is the facing area of ​​the first and second objects (i.e., the area of ​​the surface of the first object (resp. the second object) that faces the second object (resp. the first object)) (unit: m 2 ).

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[0011] Viscosity coefficient μ is expressed by equation (3) (see Reference 2). In equation (3), μ AAP is the viscosity of air at normal temperature and pressure (unit: N s / m 2 ) and K n is the Knudsen number. (Reference 2) T. Veijola et al. "Equivalent-circuit model of the squeezed gas film in a silicon accelerometer," Sensors and Actuators A-physical 48 (1995): 239-248.

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[0012] Knudsen number K n is expressed by the formula (4) (see Non-Patent Document 1). In the formula (4), λ is the mean free path (unit: m), H is the characteristic length (unit: m), d is the diameter of a gas molecule (unit: m), and P is the atmospheric pressure of the squeeze film damping structure (i.e., the atmospheric pressure of the environment in which the squeeze film damping structure is placed) (unit: N / m 2 ) The characteristic length H is the distance h between the first and second objects.

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[0013] Therefore, equation (5) holds between thermal noise f and atmospheric pressure P. From this equation, it can be seen that atmospheric pressure P can be measured by detecting thermal noise f.

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[0014] In the squeeze film damping phenomenon, the pressure distribution of a viscous fluid flow in a sufficiently narrow gap is described by the Reynolds equation, which takes into account only the squeeze effect (i.e., ignoring the wedge and stretch effects), and such a Reynolds equation holds under the condition of equation (6) (see Reference 3). In equation (6), ω is the vibration frequency of the second object, ρ is the density of the fluid, R is the molar gas constant, and M is the molar mass of the molecule. (Reference 3) JB Starr, "Squeeze-film damping in solid-state accelerometers," IEEE 4th Technical Digest on Solid-State Sensor and Actuator Workshop, Hilton Head, SC, USA, 1990, pp. 44-47, doi: 10.1109 / SOLSEN.1990.109817.

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[0015] From equations (3) and (4), equation (6) can be expressed as equation (7).

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[0016] The relationship between Ξ and P is shown in FIG. 1 using the following parameter values ​​that can be used in the configuration of the air pressure sensor 100 of the embodiment described below. As is clear from FIG. 1, the air pressure sensor 100 using the following parameter values ​​has a value of approximately 10 to 105 N / m 2 The following parameters are only an example, and the values ​​of ω and h can be determined according to the structure of the pressure sensor 100, and the values ​​of M, T, and d can be determined according to the environment in which the pressure sensor 100 is placed. ω=2π×19rad / s (natural angular frequency of Pendulum 10) h=17 μm (distance between electrodes 4d, 4e and electrodes 10a, 10b) R = 8.31 J / (K mol) M = 2.8 × 10 -2 kg / mol (molar mass of nitrogen) μ AAP =1.5×10 -5 N·s / m 2 (Viscosity coefficient of air at normal temperature and pressure) k B =1.38×10 23 J / K T=300K d=0.38nm (diameter of nitrogen molecule)

[0017] <Embodiment> The air pressure sensor 100 of the embodiment has substantially the same structure as an accelerometer having a servo mechanism. As described later, a part of the structure of the accelerometer having a servo mechanism is a squeeze film damping structure. Although there is no limitation on the structure of the accelerometer having a servo mechanism, the accelerometer having a servo mechanism shown in Figures 2 and 3 is adopted for the purpose of explaining the embodiment.

[0018] The structure of the air pressure sensor 100 will be outlined with reference to Figs. 2 and 3. The air pressure sensor 100 includes a housing 1, a pendulum 10, a torque coil 60, a permanent magnet 3, an electrode support 4, a displacement detector 30, a current output amplifier 50, a read resistor 80, and a calculator 90. One end of a rectangular flat-plate pendulum 10 made of, for example, quartz is a fixed end and is fixed to the inner wall of the housing 1. A flexure 2 is formed in a portion near the fixed end of the pendulum 10. The flexure 2 has a narrowed structure in which the pendulum 10 is thin. Therefore, the elastic deformation of the flexure 2 allows the pendulum 10 to swing like a cantilever beam. The pendulum 10 is located in a predetermined neutral position when no acceleration is applied to the air pressure sensor 100 from the outside. A torque coil 60 is fixed to the pendulum 10. An electrode 10a is fixed to one surface of the free end of the pendulum 10, and an electrode 10b is fixed to the other surface.

[0019] A permanent magnet 3 is fixed to the inner wall of the housing 1, and a magnetic field is generated in the space around the permanent magnet 3. A torque coil 60 fixed to the pendulum 10 is located in the space in this magnetic field. An electrode support 4 is attached to the inner wall of the housing 1 facing the free end of the pendulum 10. The electrode support 4 includes a base 4a and two legs 4b and 4c extending from both ends of the base 4a into the housing 1. The free end of the pendulum 10 is located in the gap between the two legs 4b and 4c. An electrode 4d is fixed to the inner surface of the leg 4b, and an electrode 4e is fixed to the inner surface of the leg 4c. The electrode 4d faces the electrode 10a attached to the pendulum 10, and the electrode 4e faces the electrode 10b attached to the pendulum 10. The electrodes 4d and 10a form a capacitor, and the electrodes 4e and 10b form a capacitor.

[0020] When an external input acceleration is applied to the air pressure sensor 100, the pendulum 10 tries to stay in its position due to inertia, but the housing 1 is displaced by the influence of the input acceleration. This causes the position of the pendulum 10 to change relative to the housing 1. Specifically, when the housing 1 is used as a reference, the flexure 2 elastically deforms, causing the pendulum 10 to tilt.

[0021] The displacement detector 30 detects the displacement of the position of the pendulum 10 relative to the housing 1, and outputs an electric signal corresponding to the displacement. In this example, the displacement detector 30 includes an oscillator circuit 31, a detector 32, and a demodulator 33. The oscillator circuit 31 generates an AC signal. The AC signal is supplied to the detector 32, which is, for example, a Wheatstone bridge circuit, and the demodulator 33. The detector 32 amplitude-modulates the AC signal based on the difference between the capacitance between the electrode 10a and the electrode 4d and the capacitance between the electrode 10b and the electrode 4e. The modulated AC signal is sent to the demodulator 33. The demodulator 33 demodulates the modulated AC signal and outputs an electric signal corresponding to the displacement of the position of the pendulum 10 relative to the housing 1. For example, the magnitude of the displacement of the position of the pendulum 10 relative to the housing 1 corresponds to the voltage of the electric signal.

[0022] The voltage output of the demodulator 33 is input to the current output amplifier 50. The output current of the current output amplifier 50 flows through the torque coil 60. At this time, a force is generated in the torque coil 60 in a direction that cancels the displacement of the position of the pendulum 10 relative to the housing 1, in relation to the magnetic field created by the permanent magnet 3. This force acts on the pendulum 10. In this way, the air pressure sensor 100 forms a feedback control system (i.e., a servo mechanism) that tries to keep the pendulum 10 in a predetermined neutral position. The current that has flowed through the torque coil 60 flows through the read resistor 80.

[0023] Although the atmospheric pressure sensor 100 employs a capacitance detection method as a displacement detection method, this is not limited to this method. For example, it is also possible to employ a method of detecting the displacement of the pendulum 10 using a light source such as laser light or an LED (light-emitting diode), or a method of detecting displacement using magnetism such as a magnetoresistance effect element.

[0024] In the above-mentioned air pressure sensor 100, the squeeze film damping structure 8 is composed of the pendulum 10 and the electrode support 4, the electrode support 4 corresponds to the first object, and the pendulum 10 corresponds to the second object. More specifically, the electrode 4d (resp. electrode 4e) of the electrode support 4 can be regarded as the first object, and the electrode 10a (resp. electrode 10b) of the pendulum 10 can be regarded as the second object.

[0025] Even when no artificial acceleration is applied to the atmospheric pressure sensor 100, collisions of gas molecules with the second object occur all the time, causing the second object to oscillate all the time. This oscillation is obtained from the voltage across the read resistor 80 as a force acting on the pendulum 10, and the above-mentioned thermal noise f can be calculated by frequency analysis of the oscillation. Specifically, in this example, when no artificial acceleration is applied to the atmospheric pressure sensor 100, the calculator 90 obtains a time series signal of the input acceleration from the voltage across the read resistor 80 (this process is performed by an accelerometer and is well known to those skilled in the art), performs FFT (fast Fourier transform) analysis on the time series signal of the force acting on the pendulum 10 calculated from the time series signal of the inertial mass and the input acceleration, and calculates the atmospheric pressure value P according to the relational expression between the thermal noise obtained by this FFT analysis and Equation (5). The calculator 90 includes, but is not limited to, a processor, a memory, and the like.

[0026] The results of the demonstration experiment of the atmospheric pressure sensor 100 are shown in Figure 4. In the demonstration experiment, a servo-type accelerometer, a product of Japan Aviation Electronics Industry, Inc., was used as the atmospheric pressure sensor 100. The parameter values ​​of the servo-type accelerometer used in the demonstration experiment are as described above. In addition, a Pirani vacuum gauge was used to measure the atmospheric pressure value. As is clear from Figure 4, the atmospheric pressure value calculated from the thermal noise measured by the atmospheric pressure sensor 100 is almost the same as the atmospheric pressure value measured by the Pirani vacuum gauge, demonstrating the usefulness of the atmospheric pressure sensor 100.

[0027] In the squeeze film damping structure 8, the thermal noise is caused by the collision of gas molecules with the second object, and therefore the amplitude of the displacement of the second object is minute. In other words, when acceleration is applied to the atmospheric pressure sensor 100, it becomes difficult to detect the thermal noise. In order to detect the thermal noise even when there is an external acceleration disturbance, an atmospheric pressure sensor 200 having the configuration shown in FIG. 5 may be adopted. The atmospheric pressure sensor 200 includes two accelerometers placed in the same environment. The atmospheric pressure sensor 200 has a configuration in which two accelerometers, each having the same structure as the atmospheric pressure sensor 100, share one computing unit 90.

[0028] In the air pressure sensor 200, the calculator 90 cancels the disturbance acceleration in a common mode by using a time series signal a1(t) of the acceleration measured by one accelerometer (this acceleration includes the disturbance acceleration and the acceleration resulting from the collision of gas molecules with the second object included in one accelerometer) and a time series signal a2(t) of the acceleration measured by the other accelerometer (this acceleration includes the disturbance acceleration and the acceleration resulting from the collision of gas molecules with the second object included in the other accelerometer). Specifically, when two accelerometers are arranged so that the disturbance acceleration applied to one accelerometer and the disturbance acceleration applied to the other accelerometer have the same polarity, the disturbance acceleration is canceled in a common mode by obtaining a difference a1(t)-a2(t) between the time series signal a1(t) of the acceleration measured by one accelerometer and the time series signal a2(t) of the acceleration measured by the other accelerometer. When two accelerometers are arranged so that the disturbance acceleration applied to one accelerometer and the disturbance acceleration applied to the other accelerometer have opposite polarities, the disturbance acceleration is cancelled in a common mode by calculating the sum a1(t)+a2(t) of the time series signal a1(t) of the acceleration measured by one accelerometer and the time series signal a2(t) of the acceleration measured by the other accelerometer. The time series signal a1(t)-a2(t) or a1(t)+a2(t) obtained by common mode cancellation is calculated by taking the square root of the sum of the squares sqrt((f1(t))) of the time series signal f1(t) of the acceleration caused by the collision of gas molecules with a second object included in one accelerometer and the time series signal f2(t) of the acceleration caused by the collision of gas molecules with a second object included in the other accelerometer. 2 +(f2(t)) 2 The calculator 90 calculates the time series signal (=sqrt((f1(t))) obtained by the inertial mass and common mode cancellation. 2 +(f2(t)) 2)), and the thermal noise obtained by this FFT analysis is regarded as f in equation (5), thereby calculating the air pressure P in the environment in which the two accelerometers are placed. In short, the calculator 90 calculates the thermal noise generated in the second object included in one accelerometer and the second object included in the other accelerometer by common mode canceling the displacement (resp. speed) generated by a common disturbance from the displacement (resp. speed) of one second object and the displacement (resp. speed) of the other second object, and calculates the air pressure in the environment in which the squeeze film damping structure 8 included in one accelerometer and the squeeze film damping structure 8 included in the other accelerometer are placed from the calculated thermal noise.

[0029] According to the embodiment of the air pressure sensor 100, 200, the measurable pressure range can be easily changed by changing the structural parameters (e.g., the distance between the electrodes). Since the thermal expansion coefficient of quartz is very small, when the pendulum 10 is made of quartz, the effect on the distance between the electrodes is small, and therefore the air pressure sensor 100, 200 has good temperature independence.

[0030] The atmospheric pressure sensor 100 of the embodiment has substantially the same structure as an accelerometer having a servo mechanism, but is not limited thereto. The atmospheric pressure sensor of the present disclosure is based on the knowledge that there is a one-to-one relationship between thermal noise and atmospheric pressure by analytical expression (see formula (5)). Therefore, the essential condition of the atmospheric pressure sensor of the present disclosure is that it includes a first object and a second object that is movable relative to the first object, a squeeze film damping structure in which a squeeze film damping phenomenon occurs between the first object and the second object, and a calculator that calculates the atmospheric pressure of the squeeze film damping structure from the thermal noise generated in the second object, and it is not essential that the atmospheric pressure sensor of the present disclosure has substantially the same structure as an accelerometer having a servo mechanism. In addition, the atmospheric pressure sensor 100 of the embodiment has a measuring device (i.e., the displacement detector 30) that measures the displacement of the second object (i.e., the pendulum 10), but is not limited thereto, and may have a measuring device that measures the speed of the second object (i.e., the pendulum 10). The displacement is obtained by integrating the speed.

[0031] <Addendum 1> The technical features disclosed in the above-mentioned various embodiments and their modifications are not necessarily mutually exclusive. As long as there is no contradiction from a technical point of view, the technical features of one embodiment or its modifications may be applied to the technical features of another embodiment or its modifications.

[0032] The claims set forth in the claims section at the time of filing of this application do not necessarily exhaustively claim all inventions disclosed in this specification. In this regard, it should not be understood or interpreted that the applicant of this application has waived the right to obtain a patent for any invention not claimed at the time of filing of this application. To the extent permitted by the laws, regulations or treaties of the country or region in which this application is accepted, the applicant of this application reserves the right to obtain a patent for any invention not claimed in this application, the right to file a divisional application for such invention, the right to claim such invention by amendment, and any other rights, unless the applicant of this application expressly and conclusively expresses an intention to the contrary.

[0033] An example of a summary of the present disclosure based on another aspect is as follows:

[0034] The air pressure sensor of the first invention includes a first object and a second object that is movable relative to the first object, a squeeze film damping structure in which the squeeze film damping phenomenon occurs between the first object and the second object, and a calculator that calculates the ambient pressure of the squeeze film damping structure from thermal noise generated in the second object.

[0035] A second invention is an air pressure sensor according to the first invention, characterized in that it includes a measuring instrument that measures the displacement or speed of the second object, and the calculator calculates thermal noise from the displacement or speed of the second object.

[0036] A third invention is an air pressure sensor according to the first or second invention, characterized in that the second object is a cantilever-shaped oscillator.

[0037] A fourth invention is the air pressure sensor according to any one of the first to third inventions, further comprising:

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[0038] The air pressure sensor of the fifth invention includes a first object and a second object movable relative to the first object, a first squeeze film damping structure in which a squeeze film damping phenomenon occurs between the first object and the second object, a third object and a fourth object movable relative to the third object, a second squeeze film damping structure in which a squeeze film damping phenomenon occurs between the third object and the fourth object, a measuring instrument that measures the displacement of the second object, a measuring instrument that measures the displacement of the fourth object, and a measurement device that measures the measured displacement of the second object and the displacement of the fourth object. The present invention includes a calculator that calculates thermal noise generated in the second object and the fourth object (as a specific example, this thermal noise is the root mean square of the thermal noise generated in the second object and the thermal noise generated in the fourth object, and this root mean square essentially corresponds to the arithmetic average of the thermal noise generated in the second object and the thermal noise generated in the fourth object) by common mode canceling the displacement generated by a common disturbance from the measured displacement, and calculates the ambient pressure of the first squeeze film damping structure and the second squeeze film damping structure from the calculated thermal noise.

[0039] A sixth invention provides an air pressure sensor according to the fifth invention, characterized in that the second object and / or the fourth object is a cantilever-shaped oscillator.

[0040] A seventh aspect of the present invention is the air pressure sensor according to the fifth or sixth aspect of the present invention, further comprising:

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[0041] An eighth aspect of the present invention is an air pressure sensor according to any one of the fifth to seventh aspects of the present invention, characterized in that "displacement" is read as "speed".

[0042] A ninth invention is an air pressure sensor according to any one of the fifth to eighth inventions, characterized in that the first squeeze film damping structure is the same as the second squeeze film damping structure.

[0043] <Addendum 2> Although the invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes can be made and elements thereof substituted with equivalents without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular system, device, or component thereof to the teachings of the invention without departing from the essential scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

[0044] Furthermore, the use of terms such as "first", "second", etc., does not indicate any order or importance, and terms such as "first", "second", etc., are used to distinguish elements. The terms used herein are for the purpose of describing the embodiments and are not intended to limit the invention in any way. The term "comprises" and its conjugations, when used in this specification and / or the appended claims, disclose the presence of the mentioned features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The term "and / or" includes any and all combinations of one or more of the associated listed elements, if any. In the claims and the specification, unless otherwise stated, the terms "connected", "coupled", "joined", "connected", or all of their synonyms, and all of their conjugations, do not necessarily negate the presence of one or more intermediate elements between two elements that are, for example, "connected" or "coupled" to each other or "connected" to each other.

[0045] Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art and this disclosure, and should not be interpreted ideally or excessively formally unless explicitly defined.

[0046] It will be understood that in the description of the present invention, many techniques and steps are disclosed. Each of these has separate advantages and each can be used in combination with one or more, or in some cases all, of the other disclosed techniques. Thus, to avoid cluttering, this specification refrains from describing every possible combination of individual techniques or steps. Nevertheless, the specification and claims should be read with the understanding that such combinations are fully within the scope of the present invention and claims.

[0047] The corresponding structure, materials, acts, and equivalents of all functional elements combined with means or steps in the following claims are intended to include the structures, materials, or acts, if any, for performing the function in combination with other claimed elements.

[0048] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Various modifications and variations are permitted within the scope of the present invention. The selected and described embodiments are intended to illustrate the principles of the present invention and its practical application. The present invention is used in various embodiments with various modifications and variations, and the various modifications and variations are determined according to the expected use. All such modifications and variations are intended to be included within the scope of the present invention as defined by the appended claims, and are intended to be accorded the same protection when interpreted in accordance with the breadth that is fairly, legally and equitably entitled thereto. [Explanation of symbols]

[0049] 1. Housing 2 Flexure 3. Permanent magnets 4 Electrode support 4a base 4b Legs 4c Legs 4d electrode 4e electrode 8 Squeeze film damping structure 10 Pendulum 10a electrode 10b electrode 30 Displacement detector 31 Oscillator Circuit 32 Detector 33 Demodulator 50 Current Output Amplifier 60 Torque coil 80 Read Resistance 90 Arithmetic unit 100 Barometric pressure sensor 200 Barometric pressure sensor

Claims

1. An air pressure sensor, a squeeze film damping structure including a first object and a second object movable relative to the first object, where a squeeze film damping phenomenon occurs between the first object and the second object; a calculator for calculating an atmospheric pressure of the squeeze film damping structure from thermal noise generated in the second object; a barometric pressure sensor including

2. 2. The air pressure sensor according to claim 1, a measuring device for measuring a displacement or a speed of the second object; The calculator calculates the thermal noise from the displacement or the speed of the second object. A pressure sensor characterized by:

3. 2. The air pressure sensor according to claim 1, The second object is a cantilever oscillator. A pressure sensor characterized by:

4. 2. The air pressure sensor according to claim 1, Between the thermal noise and the atmospheric pressure, [0089] holds, except that f is the thermal noise, P is the atmospheric pressure, k B is the Boltzmann constant, T is the ambient temperature of the squeeze film damping structure; S is the facing area between the first object and the second object, h is the distance between the first object and the second object; μ AAP is the viscosity of air at normal temperature and pressure, d is the diameter of the gas molecule, A pressure sensor characterized by:

5. An air pressure sensor, a first squeeze film damping structure including a first object and a second object movable relative to the first object, where a squeeze film damping phenomenon occurs between the first object and the second object; a second squeeze film damping structure including a third object and a fourth object movable relative to the third object, wherein a squeeze film damping phenomenon occurs between the third object and the fourth object; a measuring device for measuring a displacement of the second object; A measuring device that measures a displacement of the fourth object; a calculator that calculates thermal noise generated in the second object and the fourth object by common mode canceling a displacement generated by a common disturbance from the measured displacement of the second object and the measured displacement of the fourth object, and calculates an atmospheric pressure of the first squeeze film damping structure and the second squeeze film damping structure from the thermal noise; a barometric pressure sensor including

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