JP2017150974A - Pressure change measuring device, altitude measuring device, and pressure change measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure a temporal change of the pressure of a measurement object.SOLUTION: A pressure change measuring device 1 includes: a cavity into which a pressure transmission medium for transmitting a measurement object pressure flows; and a communication hole for making the pressure transmission medium circulate inside and outside of the cavity. The pressure change measuring device further includes: a differential pressure sensor 110 for detecting a pressure difference detection value according to a pressure difference between the pressure inside the cavity and the measurement object pressure; a reference value setting part 60 for setting a detection reference value based on a temperature detection value detected by the temperature sensor 120 and the temperature sensor 120 for detecting the a temperature detection value according to the temperature of the differential pressure sensor 110 and a temperature characteristic of the detection reference value showing the detection value of the differential pressure sensor 110 in a state where no differential pressure exists; and a calculation processing part 70 for generating information showing the change of the measurement object pressure based on the detection reference value set by the reference value setting part 60 and the differential pressure detection value detected by the differential pressure sensor 110.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure change measuring device, an altitude measuring device, and a pressure change measuring method.

  Conventionally, as an apparatus for measuring a change in pressure of a measurement target, an inner chamber (pressure chamber), a differential pressure sensor for detecting a differential pressure between the pressure in the inner chamber and the pressure of the measurement target, and a pressure transmission medium of the measurement target are provided. A pressure change measuring device having a pressure passage hole that can flow into and out of an inner chamber is known (for example, Patent Documents 1 to 3).

Japanese Patent Laid-Open No. 48-12778 JP-A-2-52229 Japanese Patent No. 5650360

  However, while the pressure change measuring device as described above can detect the pressure change of the measurement target at a predetermined timing from the output signal, it measures the change in the pressure of the measurement target over time, that is, the change of the measurement target pressure with respect to the time axis. Difficult to do. For example, in the pressure change measuring apparatus as described above, when measuring the change over time of the pressure of the measurement target based on the obtained output signal, the pressure change of the measurement target is compared with the reference value in a state where the pressure of the measurement target is constant. It is necessary to measure how much the output signal has changed, but it is not clear how to set this reference value. For this reason, it has been difficult for the pressure change measuring apparatus as described above to measure the change over time in the pressure of the measurement object with high accuracy.

  The present invention has been made to solve the above problems, and its object is to provide a pressure change measuring device, an altitude measuring device, and a pressure change measuring method capable of measuring a change over time in pressure of a measurement object with high accuracy. Is to provide.

  In order to solve the above problem, an aspect of the present invention includes a cavity into which a pressure transmission medium that transmits a measurement target pressure flows, and a communication hole that allows the pressure transmission medium to flow inside and outside the cavity. A differential pressure sensor that detects a differential pressure detection value corresponding to a differential pressure between an internal pressure of the cavity and the pressure to be measured; a temperature sensor that detects a temperature detection value corresponding to a temperature of the differential pressure sensor; and the temperature A reference value setting unit for setting the detection reference value based on the temperature detection value detected by the sensor and a temperature characteristic of a detection reference value indicating the detection value of the differential pressure sensor in a state without the differential pressure; An arithmetic processing unit that generates information indicating a change in the measurement target pressure based on the detection reference value set by the reference value setting unit and the differential pressure detection value detected by the differential pressure sensor A pressure change measuring apparatus comprising: a.

  One embodiment of the present invention is the pressure change measuring apparatus according to the first aspect, wherein the differential pressure sensor includes a sensor body having the cavity and a distal end from the proximal end so as to close an opening surface of the cavity excluding the communication hole. A cantilever that is unidirectionally extending toward the portion and bends and deforms according to a pressure difference between the inside and the outside of the cavity, and a resistance change of the base end portion according to the bending deformation of the cantilever. And a differential pressure detection circuit section for detecting the differential pressure detection value.

  According to another aspect of the present invention, in the pressure change measuring apparatus, the differential pressure sensor includes a reference portion having a lever portion configured to have the same material and shape as the cantilever, and the difference The pressure detection circuit unit includes a Wheatstone bridge circuit having a detection resistance including a resistance of a proximal end portion of the cantilever and a reference resistance including a resistance of a proximal end portion of the lever portion.

  One embodiment of the present invention is the pressure change measuring apparatus according to the first aspect, wherein the temperature sensor includes a body portion having a cavity, the same material and the same shape as the cantilever, and the cavity of the body portion. A temperature detection resistor unit configured to cover and a temperature detection circuit unit that detects the temperature detection value based on a resistance change of the temperature detection resistor unit.

  One embodiment of the present invention is characterized in that, in the pressure change measuring apparatus, the cantilever includes a piezoresistor formed of an impurity semiconductor layer at least at the base end.

  Further, according to one aspect of the present invention, in the pressure change measurement apparatus, the reference value setting unit is based on the temperature detection value, a temperature characteristic of the temperature detection value, and a temperature characteristic of the detection reference value. The detection reference value is set.

  In one embodiment of the present invention, in the pressure change measuring apparatus, the reference value setting unit estimates the temperature of the differential pressure sensor based on the temperature detection value and a temperature characteristic of the temperature detection value. The detection reference value is set based on the estimated temperature of the differential pressure sensor and a temperature characteristic of the detection reference value.

  In one embodiment of the present invention, in the pressure change measurement apparatus, the reference value setting unit is configured to generate the temperature generated based on a temperature characteristic of the temperature detection value and a temperature characteristic of the detection reference value. The detection reference value is calculated based on a calculation formula for calculating the detection reference value from a detection value and the temperature detection value.

  In one embodiment of the present invention, in the pressure change measurement apparatus, the reference value setting unit is configured to generate the temperature generated based on a temperature characteristic of the temperature detection value and a temperature characteristic of the detection reference value. The detection reference value is generated based on a conversion table that associates a detection value with the detection reference value and the temperature detection value.

  An aspect of the present invention includes the pressure change measuring device described above, and an altitude converting unit that converts the change in the measurement target pressure obtained from the pressure change measuring device into altitude information. It is a measuring device.

  Another aspect of the present invention includes a cavity into which a pressure transmission medium that transmits a pressure to be measured flows, and a communication hole that allows the pressure transmission medium to flow inside and outside the cavity. A pressure change measurement method using a differential pressure sensor that detects a differential pressure detection value according to a differential pressure with respect to the measurement target pressure, wherein a reference value setting unit detects a temperature detection value according to the temperature of the differential pressure sensor A reference for setting the detection reference value based on the temperature detection value detected by the temperature sensor for detecting the temperature and a temperature characteristic of a detection reference value indicating the detection value of the differential pressure sensor in a state without the differential pressure The measurement target pressure based on the value setting step and the detection reference value set by the reference value setting step and the differential pressure detection value detected by the differential pressure sensor; A pressure change measurement method which comprises a processing step of generating information indicating a change.

  ADVANTAGE OF THE INVENTION According to this invention, the time-dependent change of the pressure of a measuring object can be measured with high precision.

It is a functional block diagram which shows an example of the pressure change measuring apparatus by 1st Embodiment. It is a top view which shows an example of the sensor chip in 1st Embodiment. It is sectional drawing of the sensor chip along the AA line shown in FIG. It is sectional drawing of the sensor chip along the BB line shown in FIG. It is a figure which shows an example of the output signal of the differential pressure sensor in 1st Embodiment. It is a figure which shows an example of operation | movement of the differential pressure sensor in 1st Embodiment. It is a flowchart which shows an example of operation | movement of the pressure change measuring apparatus in 1st Embodiment. It is a figure explaining an example of operation | movement of the reference value setting part in 1st Embodiment. It is another figure explaining an example of operation | movement of the reference value setting part in 1st Embodiment. It is a flowchart which shows an example of operation | movement of the arithmetic processing part in 1st Embodiment. It is a figure explaining an example of operation | movement of the arithmetic processing part in 1st Embodiment. It is a figure which shows an example of the conversion table in 3rd Embodiment. It is a top view which shows an example of the sensor chip in 4th Embodiment. It is sectional drawing of the sensor chip along the AA line shown in FIG. It is sectional drawing of the sensor chip along the BB line shown in FIG. It is a top view which shows an example of the sensor chip in 5th Embodiment. It is sectional drawing of the sensor chip along the BB line shown in FIG. It is a functional block diagram which shows an example of the pressure change measuring apparatus by 6th Embodiment. It is a functional block diagram which shows an example of the altitude measurement apparatus by 7th Embodiment.

Hereinafter, a pressure change measuring device and an altitude measuring device according to an embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is a functional block diagram showing an example of a pressure change measuring device 1 according to the first embodiment.
As shown in FIG. 1, the pressure change measuring device 1 includes a differential pressure sensor 110, a temperature sensor 120, a reference value setting unit 60, and an arithmetic processing unit 70.

  The differential pressure sensor 110 detects a change in pressure (measuring target pressure) of a medium to be measured (for example, a fluid such as air), and the internal pressure of the cavity 10 (see FIG. 3) described later and the measuring target pressure ( A differential pressure detection value corresponding to the differential pressure with respect to the external pressure is detected. The differential pressure sensor 110 includes a differential pressure detection circuit unit 40 that detects a differential pressure detection value.

The differential pressure detection circuit unit 40 includes a Wheatstone bridge circuit 41 and a differential amplifier circuit 42.
The Wheatstone bridge circuit 41 includes a resistor R1 (detection resistor Rsen) included in a differential pressure sensor unit 111 described later, a resistor R2 (reference resistor Rref) included in a reference unit 112 described later, a resistor R3, and a resistor R4. Yes.
The resistor R1 (detection resistor Rsen) has a first end connected to the power supply line Vcc and a second end connected to the node N1, and the resistance changes according to the differential pressure inside and outside the cavity 10. The resistor R2 (reference resistor Rref) has a first end connected to the node N1 and a second end connected to the power supply line GND, and is a reference for reducing a detection error due to temperature dependence of the differential pressure detection value and resistance value variation. Resistance.
The resistor R3 has a first end connected to the power supply line Vcc and a second end connected to the node N2. The resistor R4 has a first end connected to the node N2 and a second end connected to the power supply line GND. The resistors R1 and R2 are configured in a sensor chip 100 described later, and the resistors R3 and R4 are external resistors provided outside the sensor chip 100.

  The differential amplifier circuit 42 is, for example, a measurement amplifier (instrumentation amplifier), and amplifies the potential difference between the node N1 and the node N2 and outputs the amplified signal as an output signal S1. In the differential amplifier circuit 42, the inverting input terminal (− terminal) is connected to the node N1, and the non-inverting input terminal (+ terminal) is connected to the node N2.

The temperature sensor 120 detects a temperature detection value corresponding to the temperature (for example, ambient temperature) of the differential pressure sensor 110. The temperature sensor 120 includes a temperature detection circuit unit 50 that detects a temperature detection value.
The temperature detection circuit unit 50 includes a Wheatstone bridge circuit 51 and a differential amplifier circuit 52.
The Wheatstone bridge circuit 51 includes a resistor R5 (detection resistor Rtmp), a resistor R6, a resistor R7, and a resistor R8 included in a temperature sensor unit 121 described later.
The resistor R5 (detection resistor Rtmp) has a first end connected to the power supply line Vcc and a second end connected to the node N3, and the resistance value changes according to the temperature of the differential pressure sensor 110. The resistor R6 has a first end connected to the node N3 and a second end connected to the power supply line GND.
The resistor R7 has a first end connected to the power supply line Vcc and a second end connected to the node N4. A resistor R8 has a first end connected to the node N4 and a second end connected to the power supply line GND. The resistor R5 is configured in the sensor chip 100 described later, and the resistors R6, R7, and R8 are external resistors provided outside the sensor chip 100.

The differential amplifier circuit 52 is, for example, a measurement amplifier (instrumentation amplifier), and amplifies the potential difference between the node N3 and the node N4 and outputs it as an output signal S2. In the differential amplifier circuit 52, an inverting input terminal (− terminal) is connected to the node N3, and a non-inverting input terminal (+ terminal) is connected to the node N4.
The sensor chip 100 includes a differential pressure sensor 110, a differential pressure sensor unit 111, and a reference unit 112, and the resistor R1, the resistor R2, and the resistor R5 are configured on the same semiconductor substrate in the sensor chip 100. Has been. Details of the configuration of the sensor chip 100 will be described later.

The reference value setting unit 60 is based on the temperature detection value (the value of the signal S2) detected by the temperature sensor 120 and the temperature characteristic of the detection reference value indicating the detection value of the differential pressure sensor 110 in a state where there is no differential pressure. Set the detection reference value. For example, the reference value setting unit 60 sets the detection reference value based on the temperature detection value, the temperature characteristic of the temperature detection value, and the temperature characteristic of the detection reference value. Specifically, the reference value setting unit 60 estimates the temperature of the differential pressure sensor 110 based on, for example, the temperature detection value and the temperature characteristics of the temperature detection value, and detects the detected temperature of the differential pressure sensor 110 and the detected temperature. The detection reference value is set based on the temperature characteristic of the reference value.
The reference value setting unit 60 includes a temperature characteristic storage unit 61 and a reference value generation unit 62.

The temperature characteristic storage unit 61 stores various temperature characteristic data used for generating (estimating) the detection reference value. The temperature characteristic storage unit 61, for example, a temperature detection of a temperature characteristic of a detection reference value indicating a relationship between the temperature of the differential pressure sensor 110 and a detection reference value, a temperature of the temperature sensor 120, and a temperature detection value indicating a relationship between the temperature detection values. Stores temperature characteristics of values.
In this embodiment, as an example of the temperature characteristic of the detection reference value, the temperature characteristic storage unit 61 changes the temperature of the differential pressure sensor 110 and associates the temperature value with the detection reference value. Data (reference value conversion table) is stored. Further, the temperature characteristic storage unit 61 changes the temperature of the temperature sensor 120 as an example of the temperature characteristic of the temperature detection value, and associates the temperature value with the temperature detection value (temperature conversion table). Remember.

  The reference value generation unit 62 estimates the temperature of the differential pressure sensor 110 based on the temperature detection value detected by the temperature sensor 120 and the temperature characteristic of the temperature detection value stored in the temperature characteristic storage unit 61. That is, the reference value generation unit 62 estimates the temperature of the differential pressure sensor 110 by acquiring a temperature value corresponding to the temperature detection value acquired from the temperature sensor 120 from the temperature conversion table of the temperature characteristic storage unit 61. When the temperature detection value does not exist in the temperature conversion table, the reference value generation unit 62 may acquire a temperature value corresponding to the closest temperature detection value, for example, using linear interpolation. The temperature value may be estimated.

  Further, the reference value generation unit 62 sets the detection reference value based on the estimated temperature of the differential pressure sensor 110 and the temperature characteristic of the detection reference value. That is, the reference value generation unit 62 acquires the detection reference value corresponding to the temperature value acquired from the temperature conversion table of the temperature characteristic storage unit 61 from the reference value conversion table of the temperature characteristic storage unit 61, thereby detecting the detection reference value. Is generated (set). When the temperature value does not exist in the reference value conversion table, the reference value generation unit 62 may acquire a detection reference value corresponding to the closest temperature value, for example, using linear interpolation. The detection reference value may be estimated. The reference value generation unit 62 outputs the acquired detection reference value to the arithmetic processing unit 70 as the output signal S3.

The arithmetic processing unit 70 indicates a change in the measurement target pressure based on the detection reference value set by the reference value setting unit 60 and the differential pressure detection value (the value of the signal S1) detected by the differential pressure sensor 110. Generate information. The arithmetic processing unit 70 outputs pressure change information indicating the calculated change in the measurement target pressure. In the present embodiment, it is assumed that the arithmetic processing unit 70 outputs a pressure value (external pressure value Pout) outside the cavity 10 as an example of pressure change information.
The arithmetic processing unit 70 includes a table storage unit 71, an internal pressure value storage unit 72, and a pressure calculation unit 73.

The table storage unit 71 stores various conversion tables used for calculating the external pressure value Pout. The table storage unit 71 stores, for example, a differential pressure value conversion table and a flow rate conversion table. The differential pressure value conversion table is a table showing the relationship between the change rate (ΔR / R) of the resistor R1 and the differential pressure value ΔP inside and outside the cavity 10, and the change rate (ΔR / R) of the resistor R1 and the difference It is the table which matched pressure value (DELTA) P. The flow rate conversion table is a table showing the relationship between the differential pressure value ΔP and the flow rate Q of air moving in and out of the cavity 10, and is a table in which the differential pressure value ΔP and the flow rate Q are associated with each other.
The internal pressure value storage unit 72 stores an internal pressure value Pin that is an estimated value at the next measurement.

  Based on the differential pressure detection value Vsen detected by the differential pressure sensor 110 and the detection reference value Vref set by the reference value setting unit 60, the pressure calculation unit 73 excludes an accurate fluctuation voltage ΔVp excluding the temperature fluctuation. Is calculated. Here, the fluctuation voltage ΔVp is expressed by the following equation (1).

  The pressure calculation unit 73 calculates the fluctuation voltage ΔVp using the formula (1). Next, the pressure calculation unit 73 divides the fluctuation voltage ΔVp by the amplification factor (gain value) of the differential amplifier circuit 42, and also supplies the voltage of the power line Vcc supplied to the Wheatstone bridge circuit 41 and the resistor R2. Based on the resistance values of .about.R4, the resistance value (R + ΔR) of the resistor R1 is calculated. Here, the resistance value R indicates the resistance value of the resistor R1 when the differential pressure value ΔP is “0”, and the resistance value ΔR indicates the resistance value of the change in the resistance R1 that has changed due to the differential pressure value ΔP. Further, the pressure calculation unit 73 acquires the differential pressure value ΔP corresponding to the rate of change (ΔR / R) of the resistor R1 from the differential pressure value conversion table of the table storage unit 71.

  Further, the pressure calculation unit 73 calculates the external pressure value Pout based on the internal pressure value Pin stored in the internal pressure value storage unit 72, the differential pressure value ΔP acquired from the differential pressure value conversion table, and the following equation (2). calculate. The pressure calculation unit 73 outputs the calculated external pressure value Pout to the outside of the pressure change measurement device 1.

  Further, the pressure calculation unit 73 acquires the flow rate Q corresponding to the differential pressure value ΔP from the flow rate conversion table of the table storage unit 71. The pressure calculation unit 73 calculates the internal pressure value Pin at the next measurement using the following formula (3) from the acquired flow rate Q.

Here, the variable i indicates the sample number (measurement number), the variable Vc indicates the volume of the cavity 10, and the variable Δt indicates the measurement time interval (sample interval). The internal pressure value Pin (i) indicates the current internal pressure value, and the internal pressure value Pin (i + 1) indicates the internal pressure value at the next measurement.
The pressure calculation unit 73 causes the internal pressure value storage unit 72 to store the calculated internal pressure value Pin (i + 1) at the next measurement.

Next, the configuration of the sensor chip 100 will be described with reference to FIGS.
FIG. 2 is a plan view showing an example of the sensor chip 100 in the present embodiment. FIG. 3 is a cross-sectional view of the sensor chip 100 along the line AA shown in FIG. FIG. 4 is a cross-sectional view of the sensor chip 100 along the line BB shown in FIG.
As shown in FIGS. 1 to 3, the sensor chip 100 of this embodiment includes a sensor body 2 having a rectangular parallelepiped outer shape formed by using an SOI substrate 5, and includes a differential pressure sensor unit 111 and a reference unit 112. And a temperature sensor unit 121.

  The differential pressure sensor unit 111 is a sensor that detects pressure fluctuations in a predetermined frequency band (for example, a low frequency band of 1 Hz or less), and is disposed in a space where a pressure transmission medium (for example, gas such as air) exists. used. The differential pressure sensor unit 111 includes a sensor main body 2 having a cavity 10 and a cantilever 3 in which a distal end portion 3a is a free end and a proximal end portion 3b is cantilevered.

In the present embodiment, the cantilever 3 side along the thickness direction (Z-axis direction) of the sensor chip 100 is referred to as the upper side, and the opposite side is referred to as the lower side. The short direction perpendicular to the longitudinal direction (X-axis direction) in plan view of the chip 100 will be described as the Y-axis direction.
As shown in FIG. 3, the SOI substrate 5 is a substrate in which a silicon support layer 5a, an insulating layer 5b having electrical insulation such as a silicon oxide film, and a silicon active layer 5c are thermally bonded. .

The sensor body 2 is formed of, for example, a silicon support layer 5a on the SOI substrate 5.
Specifically, the sensor body 2 has a bottom wall portion 2a and a peripheral wall portion 2b, and is formed in a hollow bottomed cylindrical shape that opens upward. The internal space of the sensor body 2 functions as a cavity (air chamber) 10, and the portion opened upward functions as a communication opening 11 that communicates the inside and the outside of the cavity 10. That is, the hollow sensor body 2 has a cavity 10 formed therein, and has a communication opening 11 that communicates the inside and the outside of the cavity 10.

The insulating layer 5b is an oxide layer formed of, for example, SiO2 (silicon dioxide). It is formed in an annular shape over the entire circumference on the opening edge of the peripheral wall 2b of the sensor body 2.
The silicon active layer 5c is formed on the insulating layer 5b so as to close the sensor body 2 from above. In the silicon active layer 5c, a gap G1 (partition groove) having a U-shape (C shape) in plan view that penetrates the silicon active layer 5c in the thickness direction (Z-axis direction) is formed. Thereby, the annular frame portion 13 and the cantilever 3 are formed in the silicon active layer 5c.
The gap G <b> 1 is formed in a region located inside the communication opening 11 in a plan view (in a region communicating with the inside of the cavity 10), and functions as a communication hole through which the pressure transmission medium flows inside and outside the cavity 10.

  The cantilever 3 has a cantilever structure in which the base end portion 3b is integrally connected to the inside of the opening end of the peripheral wall portion 2b in the sensor body 2 via the frame portion 13, and the tip end portion 3a is a free end. The communication opening 11 is arranged to be covered. That is, the cantilever 3 has a plate shape extending in one direction from the base end 3b toward the tip end 3a so as to close the opening surface of the cavity 10 excluding the gap G1 (communication hole). It bends and deforms according to the pressure difference. The cantilever 3 has a lever main body 20, a plurality of lever support portions 21 that connect the lever main body 20 and the sensor main body 2 and supports the lever main body 20 in a cantilever state, and covers the communication opening 11. Placed in.

  At the base end portion 3b of the cantilever 3, a gap G2 (partition groove) having a U-shape (C shape) in plan view that penetrates the cantilever 3 in the thickness direction (Z-axis direction) is formed. The gap G <b> 2 is disposed at the center of the sensor chip 100 in the short side direction (Y-axis direction) at the base end portion 3 b of the cantilever 3. Thus, the cantilever 3 is structured to be easily bent and deformed around the base end 3b.

The two lever support portions 21A and 21B are arranged so as to be arranged in the short direction (Y-axis direction) with the gap G2 interposed therebetween, and connect the lever main body 20 and the frame portion 13 and hold the lever main body 20 in a cantilever state. I support it. Accordingly, the cantilever 3 is bent and deformed around these lever support portions 21A and 21B.
Note that the support widths along the short direction (Y-axis direction) of the two lever support portions 21 are the same. Therefore, when the cantilever 3 is bent and deformed, the stress per unit area acting on the one lever support portion 21 and the stress per unit area acting on the other lever support portion 21 are equal.

  In the silicon active layer 5c on which the cantilever 3 is formed, a doped layer 6 (impurity semiconductor layer) which is a piezoresistor (resistance element) is formed over the entire surface of the silicon active layer 5c. The doped layer 6 is formed by doping a doping material (impurity) such as phosphorus by various methods such as an ion implantation method and a diffusion method.

Of the doped layer 6, the portion where the cantilever 3 is formed (including the portion formed on the lever support portion 21) functions as the resistor R <b> 1 (detection resistor Rsen) described above. The resistance value of the resistor R1 changes according to the amount of bending of the lever support portion 21.
On the top surface of the doped layer 6, electrodes (D 1, D 2) made of a conductive material (for example, Au (gold)) having a lower electrical resistivity than the doped layer 6 are formed. The electrodes (D1, D2) are formed in a frame shape surrounding the cantilever 3 in plan view, and are separated into an electrode D1 and an electrode D2 by a gap G1 and a gap G5. The electrode D1 functions as the first end of the resistor R1 (detection resistor Rsen), is connected to the power supply line Vcc, and the electrode D2 functions as the second end of the resistor R1 (detection resistor Rsen). The inverting input terminal (− terminal) of the circuit 42 is connected.

  The reference portion 112 includes the lever portion 4 configured to be the same material and shape as the cantilever 3. In the present embodiment, the reference portion 112 is configured symmetrically with the differential pressure sensor portion 111 around the center line in the short direction (Y-axis direction) of the sensor chip 100, and the lever portion 4 and the gap G3, a gap G4, and electrodes (D2, D3) are included. In addition, the reference part 112 is comprised so that it may become the same material and the same shape except the point which does not have a cavity, as shown in FIG.

Like the cantilever 3, the lever portion 4 includes a doped layer 6, and the doped layer 6 functions as the resistor R 2 (reference resistor Rref) described above, but is fixed and generated without a cavity. The resistance value of the resistor R2 is not affected by fluctuations in the measurement target pressure.
In the reference portion 112, the electrodes (D2, D3) are separated into the electrode D2 and the electrode D3 by the gap G2 and the gap G5. The electrode D2 functions as a first end of the resistor R2 (reference resistor Rsen), is connected to the non-inverting input terminal (+ terminal) of the differential amplifier circuit 42, and the electrode D2 is connected to the resistor R1 (reference resistor Rsen). And the power supply line GND is connected.

  As shown in FIGS. 2 and 4, the temperature sensor unit 121 includes an electrode D4, an electrode D5, and a doped layer 6 as a piezoresistor. The doped layer 6 functions as the resistor R5 described above, and the doped layer 6 (resistor R5) is formed between the gap G5 and the gap G6, and is formed as a long rectangle in the longitudinal direction (X-axis direction). ing. The electrode D4 functions as a first end of the resistor R5 (detection resistor Rtmp), is connected to the power supply line Vcc, and the electrode D5 functions as a second end of the resistor R5 (detection resistor Rtmp), and is differentially amplified. The inverting input terminal (− terminal) of the circuit 52 is connected.

Next, the operation of the pressure change measuring apparatus 1 according to this embodiment will be described with reference to the drawings.
First, the operation of the differential pressure sensor 110 according to the present embodiment will be described with reference to FIGS. 5 and 6.
FIG. 5 is a diagram illustrating an example of an output signal of the differential pressure sensor 110 according to the present embodiment. FIG. 6 is a diagram illustrating an example of the operation of the differential pressure sensor 110 according to the present embodiment.
FIG. 5A shows changes with time in the external pressure (Pout) and the internal pressure (Pin), and FIG. 5B shows changes with time in the output signal of the differential pressure sensor 110.

  First, as shown in FIG. 6A, when the external pressure (Pout) and the internal pressure (Pin) are equal and the differential pressure (ΔP) is zero as in the period A in FIG. The cantilever 3 is not bent and deformed. Here, as in the period B after time t in FIG. 5A, for example, when the external pressure (Pout) rises stepwise, the internal pressure (Pin) cannot change rapidly, and a differential pressure (ΔP) is generated. Therefore, as shown in FIG. 6B, the cantilever 3 is bent and deformed toward the inside of the cavity 10. Then, stress is applied to the dope layer 6 (resistor R1) in accordance with the bending deformation of the cantilever 3, and the resistance value changes, so that the output signal of the differential pressure sensor 110 is output from the cantilever 3 as shown in FIG. Increases in accordance with the amount of deflection (displacement).

Further, after the increase of the external pressure (Pout) (after time t1), the pressure transmission medium gradually flows from the outside to the inside of the cavity 10 via the gap G1. For this reason, as shown in FIG. 5A, the internal pressure (Pin) rises with a slower response than the fluctuation of the external pressure (Pout) while being delayed from the external pressure (Pout) as time passes.
As a result, since the internal pressure (Pin) gradually approaches the external pressure (Pout), the deflection of the cantilever 3 gradually decreases, and the differential pressure sensor 110 outputs an output signal that gradually decreases as shown in FIG. Is output (period C).

  When the internal pressure (Pin) becomes the same as the external pressure (Pout) as in the period D after time t3 shown in FIG. 5A, the bending deformation of the cantilever 3 is eliminated as shown in FIG. 6C. Then, the initial state shown in FIG. Further, as shown in FIG. 5B, the output signal of the differential pressure sensor 110 also returns to the same value as in the initial state of period A.

  The output signal of the differential pressure sensor 110 is an addition of the reference voltage in the initial state and a signal amplified based on the resistance change of the doped layer 6 (resistor R1). The reference voltage in the initial state is the difference between the voltage difference (potential difference) between the node N1 and the node N2 of the Wheatstone bridge circuit 41 illustrated in FIG. 1 when the differential pressure (ΔP) applied to the cantilever 3 is zero. It becomes the voltage value amplified by. The reference value setting unit 60 detects a reference voltage (detected) in an initial state, that is, a state where the differential pressure (ΔP = Pout−Pin) between the internal pressure (Pin) and the external pressure (Pout) is “0” (the state where there is no differential pressure). Set the reference value as an estimate.

Next, the operation of the pressure change measuring apparatus 1 in the present embodiment will be described with reference to FIG.
FIG. 7 is a flowchart showing an example of the operation of the pressure change measuring apparatus 1 in the present embodiment.
As shown in FIG. 7, in the pressure change measuring apparatus 1, first, the temperature sensor 120 and the differential pressure sensor 110 detect detection values (S101). That is, the temperature detection circuit unit 50 of the temperature sensor 120 detects a detection value (temperature detection value) corresponding to the temperature of the differential pressure sensor 110. Further, the differential pressure detection circuit unit 40 of the differential pressure sensor 110 detects a detection value (differential pressure detection value) corresponding to the differential pressure between the internal pressure and the external pressure of the cavity 10.

  Next, the pressure change measuring apparatus 1 sets a detection reference value based on the detection value (temperature detection value) of the temperature sensor 120 and the temperature characteristic of the detection reference value of the differential pressure sensor 110 (step S102). That is, the reference value setting unit 60 of the pressure change measuring device 1 estimates the temperature of the differential pressure sensor 110 based on the temperature detection value detected by the temperature sensor 120 and the temperature characteristics of the temperature detection value. A detection reference value is generated based on the temperature of the differential pressure sensor 110 and the temperature characteristics of the detection reference value. The reference value setting unit 60 outputs and sets the generated detection reference value to the arithmetic processing unit 70. Details of the detection reference value setting process by the reference value setting unit 60 will be described later with reference to FIGS.

  Next, the pressure change measurement device 1 generates information indicating a change in the measurement target pressure based on the detection reference value and the detection value (differential pressure detection value) of the differential pressure sensor 110 (step S103). Based on the detection reference value set by the reference value setting unit 60 and the internal pressure value Pin stored in the internal pressure value storage unit 72, the arithmetic processing unit 70 of the pressure change measuring device 1 is an external pressure value Pout that is a measurement target pressure. Is calculated as information indicating a change in pressure to be measured. Further, the arithmetic processing unit 70 estimates the internal pressure value Pin at the next measurement and stores it in the internal pressure value storage unit 72. Details of the operation of the arithmetic processing unit 70 will be described later with reference to FIGS. 10 and 11.

Next, the pressure change measuring device 1 outputs information indicating the change in the generated measurement target pressure (step S104). The pressure change measuring apparatus 1 ends the measurement process after the process of step S104.
In addition, the pressure change measuring apparatus 1 performs the process of step S101-step S104 regularly for every predetermined time interval.

Next, the operation of the reference value setting unit 60 will be described with reference to FIGS.
FIG. 8 is a diagram illustrating an example of the operation of the reference value setting unit 60 in the present embodiment.
In the graph shown in FIG. 8, the vertical axis indicates the output voltage [V] (volt) of the differential pressure sensor 110 and the temperature sensor 120, and the horizontal axis indicates the temperature T [° C.]. A waveform W1 indicates a change in the output voltage of the temperature sensor 120 with respect to the temperature T as a temperature characteristic of the temperature detection value. A waveform W2 indicates a change in the output voltage (detection reference value) of the differential pressure sensor 110 with no differential pressure with respect to the temperature T as the temperature characteristic of the differential pressure detection value.

  In addition, the information shown in the waveform W1 shall be previously memorize | stored in the temperature characteristic storage part 61 as a temperature conversion table, for example. Moreover, the information shown in the waveform W2 shall be beforehand memorize | stored in the temperature characteristic memory | storage part 61 as a reference value conversion table, for example.

First, the reference value generation unit 62 of the reference value setting unit 60 acquires, as the temperature of the differential pressure sensor 110, the temperature T corresponding to the temperature detection value (Vymp) that is the detection value of the temperature sensor 120 based on the waveform W1. To do. In the example shown in FIG. 8, the temperature of the differential pressure sensor 110 is a temperature T1.
Next, the reference value generation unit 62 acquires a detection reference value (Vref) corresponding to the temperature (temperature T1) of the differential pressure sensor 110 based on the waveform W2.
As described above, the reference value setting unit 60 estimates the temperature of the differential pressure sensor 110 based on the temperature detection value and the temperature characteristics of the temperature detection value, and the estimated temperature of the differential pressure sensor 110 and the detection reference. A detection reference value is generated based on the temperature characteristics of the value.

FIG. 9 is another diagram illustrating an example of the operation of the reference value setting unit 60 in the present embodiment.
In the bar graph (BG0, BG1, BG2) shown in FIG. 9, the vertical axis indicates the voltage [V]. In FIG. 9, the bar graph BG0 indicates the differential pressure detection value (Vref0) of the differential pressure sensor 110 when the temperature T = T0 in the state where there is no differential pressure in the cavity 10.

  Next, the bar graph BG1 shows an example when the temperature T = T0 and a differential pressure is generated in the cavity 10. In this example, it is shown that the differential pressure sensor 110 outputs the voltage Vsen1 as the differential pressure detection value due to the differential pressure. In this example, the difference ΔVp1 between the voltage Vsen1 and the detected differential pressure value (Vref0) is a voltage value corresponding to the differential pressure of the detected differential pressure value.

  Next, the bar graph BG2 shows an example in the case where there is the same differential pressure as in the case of the bar graph BG1 in a state where the temperature T = T0 + ΔT. In this example, it is shown that the differential pressure sensor 110 outputs the voltage Vsen2 as the differential pressure detection value due to the differential pressure. In the case of this example, the reference value setting unit 60 generates a detection reference value (Vref1) obtained by adding the temperature variation ΔVtmp1 to the detection reference value (Vref0) at the temperature T = 0 by the process shown in FIG. Therefore, the difference ΔVp1 between the voltage Vsen1 and the differential pressure detection value (Vref1) becomes a voltage value corresponding to the differential pressure of the differential pressure detection value, and the pressure change measuring device 1 corrects the fluctuation of the differential pressure detection value due to the temperature change. be able to.

Next, the operation of the arithmetic processing unit 70 will be described with reference to FIGS. 10 and 11.
FIG. 10 is a flowchart illustrating an example of the operation of the arithmetic processing unit 70 in the present embodiment. The process of the flowchart shown in this figure corresponds to step S103 in FIG.
As shown in FIG. 10, the pressure calculation unit 73 of the arithmetic processing unit 70 first calculates a detection change amount (ΔVp) based on the differential pressure detection value and the detection reference value (step S201). Based on the differential pressure detection value Vsen detected by the differential pressure sensor 110 and the detection reference value Vref set by the reference value setting unit 60, the pressure calculation unit 73 excludes an accurate fluctuation voltage ΔVp excluding the temperature fluctuation. Is calculated. For example, the pressure calculation unit 73 calculates the fluctuation voltage ΔVp corresponding to the differential pressure using the above-described equation (1).

Next, the pressure calculation unit 73 converts the detected change amount ΔVp into a differential pressure value ΔP (step S202). That is, the pressure calculation unit 73 divides the fluctuation voltage ΔVp by the amplification factor (gain value) of the differential amplifier circuit 42, and also supplies the voltage of the power supply line Vcc supplied to the Wheatstone bridge circuit 41 and the resistors R2 to R2. Based on the resistance value of R4, the resistance value (R + ΔR) of the resistor R1 is calculated. Then, the pressure calculation unit 73 acquires a differential pressure value ΔP corresponding to the rate of change (ΔR / R) of the resistor R1 from the differential pressure value conversion table of the table storage unit 71.

  Next, the pressure calculation unit 73 calculates information (external pressure value Pout) indicating a change in the measurement target pressure based on the internal pressure value Pin and the differential pressure value ΔP (step S203). That is, the pressure calculation unit 73 calculates the external pressure value Pout based on the internal pressure value Pin stored in the internal pressure value storage unit 72, the differential pressure value ΔP acquired from the differential pressure value conversion table, and the above-described equation (2). calculate.

  Next, the pressure calculation unit 73 estimates the flow rate Q from the differential pressure value ΔP (step S204). Here, the flow rate is a flow rate that moves inside and outside the cavity 10. The pressure calculation unit 73 acquires the flow rate Q corresponding to the differential pressure value ΔP from the table storage unit 71.

  Next, the pressure calculation unit 73 estimates the next internal pressure value Pin based on the flow rate Q, and stores it in the internal pressure value storage unit 72 (step S205). That is, the pressure calculation unit 73 calculates the internal pressure value Pin at the next measurement based on the flow rate Q acquired from the flow rate conversion table and the above-described equation (3). The pressure calculation unit 73 causes the internal pressure value storage unit 72 to store the calculated internal pressure value Pin at the next measurement. After the process of step S205, the pressure calculation unit 73 ends the process.

Next, FIG. 11 is a diagram illustrating an example of the operation of the arithmetic processing unit 70 in the present embodiment.
In FIG. 11, the vertical axis represents the pressure P, and the horizontal axis represents the sample number at which the measurement was performed. A waveform W3 indicates a change in the measurement target pressure (Pout).
In the example shown in FIG. 11, the i-th measurement is an initial state where there is no differential pressure value ΔP, and the internal pressure value storage unit 72 stores the internal pressure value Pin (i), which is the internal pressure initial value, as the internal pressure value Pin. Has been. Here, the pressure calculation unit 73 stores the internal pressure value Pin (i) in the internal pressure value storage unit 72 as the internal pressure value Pin (i + 1) at the next measurement.

  Next, in the (i + 1) -th measurement, a differential pressure value ΔP (i + 1) is generated, and the arithmetic processing unit 70 adds the differential pressure value ΔP () to the internal pressure value Pin (i + 1) stored in the internal pressure value storage unit 72. A value obtained by adding i + 1) is calculated as an external pressure value Pout. Further, the arithmetic processing unit 70 estimates the flow rate Q from the differential pressure value ΔP (i + 1), and calculates the internal pressure value Pin (i + 2) at the next measurement based on the flow rate Q. The pressure calculation unit 73 causes the internal pressure value storage unit 72 to store the calculated internal pressure value Pin (i + 2) at the next measurement.

Next, in the (i + 2) -th measurement, a differential pressure value ΔP (i + 2) is generated, and the arithmetic processing unit 70 adds the differential pressure value ΔP (to the internal pressure value Pin (i + 2) stored in the internal pressure value storage unit 72. A value obtained by adding i + 2) is calculated as an external pressure value Pout. Further, the arithmetic processing unit 70 estimates the flow rate Q from the differential pressure value ΔP (i + 2), and calculates the internal pressure value Pin (i + 3) at the next measurement based on the flow rate Q. The pressure calculation unit 73 causes the internal pressure value storage unit 72 to store the calculated internal pressure value Pin (i + 3) at the next measurement.
For the next (i + 3) -th measurement, the arithmetic processing unit 70 performs the same processing, and calculates a value obtained by adding the differential pressure value ΔP (i + 3) to the internal pressure value Pin (i + 3) as the external pressure value Pout. To do.

  As described above, the pressure change measuring apparatus 1 according to the present embodiment includes the differential pressure sensor 110, the temperature sensor 120, the reference value setting unit 60, and the arithmetic processing unit 70. The differential pressure sensor 110 includes a cavity 10 into which a pressure transmission medium (for example, air) that transmits a measurement target pressure (for example, air pressure) flows, and a gap G1 (communication hole) that allows the pressure transmission medium to flow inside and outside the cavity 10. ) And a differential pressure detection value corresponding to the differential pressure between the internal pressure of the cavity 10 and the pressure to be measured is detected. The temperature sensor 120 detects a temperature detection value corresponding to the temperature of the differential pressure sensor 110. The reference value setting unit 60 sets the detection reference value based on the temperature detection value detected by the temperature sensor 120 and the temperature characteristic of the detection reference value indicating the detection value of the differential pressure sensor 110 in a state where there is no differential pressure. To do. The arithmetic processing unit 70 is information (for example, an external pressure value) indicating a change in the measurement target pressure based on the detection reference value set by the reference value setting unit 60 and the differential pressure detection value detected by the differential pressure sensor 110. Pout).

  Thereby, the pressure change measuring apparatus 1 by this embodiment can set the detection reference value according to a temperature fluctuation correctly. Therefore, the pressure change measuring apparatus 1 according to the present embodiment can measure the change with time of the pressure of the measurement object with high accuracy.

In the present embodiment, the differential pressure sensor 110 is directed from the base end 3b toward the tip 3a so as to close the sensor main body 2 having the cavity 10 and the opening surface of the cavity 10 excluding the gap G1 (communication hole). It is a plate-like shape extending in one direction, and includes a cantilever 3 that bends and deforms according to a pressure difference between the inside and the outside of the cavity 10, and a differential pressure detection circuit unit 40. The differential pressure detection circuit unit 40 detects the differential pressure detection value based on the resistance change (resistance change of the resistor R1) of the base end 3b according to the bending deformation of the cantilever 3.
Thereby, in the pressure change measuring apparatus 1 according to the present embodiment, the differential pressure sensor 110 more accurately determines the differential pressure between the internal pressure of the cavity 10 and the measurement target pressure based on the resistance change according to the bending deformation of the cantilever 3. Can be detected. Since the cantilever 3 can be formed by semiconductor process technology, the cantilever 3 can be very thin (for example, several tens to several hundreds nm) in the pressure change measuring apparatus 1 according to the present embodiment. Therefore, the pressure change measuring apparatus 1 according to the present embodiment can detect minute pressure fluctuations with high accuracy.

In the present embodiment, the differential pressure sensor 110 includes the reference unit 112 having the lever unit 4 configured to be the same material and shape as the cantilever 3, and the differential pressure detection circuit unit 40 includes the cantilever 3. A Wheatstone bridge circuit 41 having a detection resistor R1 including a resistance of the base end portion 3b and a reference resistance R2 including a resistance of the base end portion of the lever portion 4.
Thereby, in the pressure change measuring device 1 according to the present embodiment, the differential pressure sensor 110 has the same material and the same shape as the resistor R1 (detection resistor Rsen) and the resistor R2 (reference resistor Rref). The influence of electromagnetic noise (for example, common noise) and temperature change can be reduced. Therefore, the pressure change measuring apparatus 1 according to the present embodiment can measure the change over time of the pressure of the measurement object with higher accuracy.

In the present embodiment, the cantilever 3 includes a piezoresistor formed of an impurity semiconductor layer (dope layer 6) at least at the base end 3b.
Thereby, in the pressure change measuring apparatus 1 according to the present embodiment, a piezoresistor can be easily added to the cantilever 3 by forming the impurity semiconductor layer (dope layer 6).
In the present embodiment, the resistor R5 included in the temperature sensor 120 is also a piezoresistor formed by the impurity semiconductor layer (dope layer 6). As a result, the temperature characteristic of the differential pressure sensor 110 and the temperature characteristic of the temperature sensor 120 can be brought close to each other. Therefore, the pressure change measuring apparatus 1 according to the present embodiment sets the detection reference value according to the temperature fluctuation more accurately. can do.

In the present embodiment, the reference value setting unit 60 sets the detection reference value based on the temperature detection value, the temperature characteristic of the temperature detection value, and the temperature characteristic of the detection reference value. That is, the reference value setting unit 60 estimates the temperature of the differential pressure sensor 110 based on the temperature detection value and the temperature characteristic of the temperature detection value, and the estimated temperature of the differential pressure sensor 110 and the temperature of the detection reference value. A detection reference value is set based on the characteristics.
Thereby, the pressure change measuring apparatus 1 by this embodiment can set the detection reference value according to a temperature fluctuation correctly with a simple method.

In the present embodiment, the resistor R1 and the resistor R2 of the differential pressure sensor 110 and the resistor R5 of the temperature sensor 120 are configured as one sensor chip 100. That is, the resistors R1 and R2 of the differential pressure sensor 110 and the resistor R5 of the temperature sensor 120 are formed on the same substrate (semiconductor substrate).
As a result, the temperature sensor 120 can more accurately detect the temperature of the differential pressure sensor 110, so that the pressure change measuring apparatus 1 according to the present embodiment can detect the temperature change according to a temperature variation using a simple method. The value can be set more accurately. Further, the temperature sensor 120 can accurately detect the temperature of the differential pressure sensor 110 that is detecting the detected differential pressure value. Therefore, the pressure change measuring apparatus 1 according to the present embodiment can reset the detection reference value every time the pressure of the measurement target is measured.

Further, the pressure change measuring method according to the present embodiment includes the cavity 10 into which the pressure transmission medium that transmits the pressure to be measured flows, and the gap G1 (communication hole) that allows the pressure transmission medium to flow inside and outside the cavity 10. A pressure change measurement method using a differential pressure sensor 110 that detects a differential pressure detection value corresponding to a differential pressure between the internal pressure of the cavity 10 and the measurement target pressure, and includes a reference value setting step and an arithmetic processing step. Including. In the reference value setting step, the reference value setting unit 60 detects the temperature detection value detected by the temperature sensor 120 that detects the temperature detection value corresponding to the temperature of the differential pressure sensor 110, and the differential pressure sensor 110 in a state where there is no differential pressure. The detection reference value is set based on the temperature characteristic of the detection reference value indicating the detected value. In the calculation processing step, the calculation processing unit 70 changes the measurement target pressure based on the detection reference value set in the reference value setting step and the differential pressure detection value indicating the detection value detected by the differential pressure sensor 110. (External pressure value Pout) is generated.
Thereby, the pressure change measuring method according to the present embodiment can measure the change over time of the pressure of the measurement object with high accuracy, like the pressure change measuring apparatus 1 described above.

[Second Embodiment]
Next, the pressure change measuring apparatus 1 according to the second embodiment will be described.
In the first embodiment described above, the example in which the reference value setting unit 60 sets the detection reference value based on the temperature conversion table and the reference value conversion table has been described. However, in the present embodiment, the calculation indicating the temperature characteristic is performed. A modification example in which the detection reference value is set based on an equation (calculation model) will be described.
The configuration of the pressure change measuring device 1 according to the present embodiment is basically the same as the configuration of the pressure change measuring device 1 of the first embodiment, and thus the description thereof is omitted here. In the present embodiment, the temperature characteristic storage unit 61 stores the coefficient information of the arithmetic expression instead of the temperature conversion table and the reference value conversion table, and the processing of the reference value setting unit 60 is different.

  In the present embodiment, the temperature characteristic of the temperature detection value of the waveform W1 shown in FIG. 8 can be expressed by the following linear function equation (4).

Here, the variable Vtmp indicates the temperature detection value of the temperature sensor 120, and the variable T indicates the temperature.
The temperature characteristic storage unit 61 of the present embodiment stores coefficient information (coefficient a ₁ and coefficient b ₁ ) of Expression (4) instead of the temperature conversion table.
Further, the temperature characteristic of the detection reference value of the waveform W2 shown in FIG. 8 can be expressed by the following linear function equation (5).

Here, the variable Vsen indicates the differential pressure detection value of the differential pressure sensor 110.
The temperature characteristic storage unit 61 of the present embodiment stores the coefficient information (coefficient a ₂ and coefficient b ₂ ) of Expression (5) instead of the reference value conversion table.

  In addition, the reference value setting unit 60 according to the present embodiment uses the coefficient information stored in the temperature characteristic storage unit 61 and the above-described equation (4) as the temperature characteristic of the temperature detection value as a temperature detection value detected by the temperature sensor 120. From the above, the temperature of the differential pressure sensor 110 is calculated. The reference value setting unit 60 calculates the detection reference value from the calculated temperature of the differential pressure sensor 110 using the coefficient information stored in the temperature characteristic storage unit 61 and the above-described equation (5) as the temperature characteristic of the detection reference value. To do.

  The relationship between the detection reference value (Vref) and the temperature detection value (Vtmp) of the temperature sensor 120 is expressed by the following equation (6) based on the above-described equations (4) and (5). it can.

The reference value setting unit 60 of the present embodiment is based on the coefficient information (coefficient a ₁ coefficient a ₂ , coefficient b ₁ , and coefficient b ₂ ) stored in the temperature characteristic storage unit 61 and the above equation (6). The detection reference value may be calculated from the temperature detection value detected by the temperature sensor 120.

As described above, in the present embodiment, the reference value setting unit 60 calculates the detection reference value from the temperature detection value generated based on the temperature characteristic of the temperature detection value and the temperature characteristic of the detection reference value. A detection reference value is calculated based on the calculation formula (formula (6)) and the temperature detection value.
Thereby, the pressure change measuring apparatus 1 according to the present embodiment can accurately set the detection reference value corresponding to the temperature fluctuation as the detection reference value by a simpler method.

[Third Embodiment]
Next, a pressure change measuring apparatus 1 according to a third embodiment will be described with reference to the drawings.
In the present embodiment, the reference value setting unit 60 is based on a conversion table for converting the detected temperature value into the detected reference value instead of the calculation expression (equation (6)) for calculating the detected reference value from the detected temperature value. A modification example in which the detection reference value is set will be described.

  Note that the configuration of the pressure change measuring apparatus 1 according to the present embodiment is basically the same as the configuration of the pressure change measuring apparatus 1 of the first and second embodiments, and thus description thereof is omitted here. In the present embodiment, the temperature characteristic storage unit 61 stores a conversion table for converting a temperature detection value into a detection reference value instead of the temperature conversion table and the reference value conversion table, and the processing of the reference value setting unit 60 is performed. Different.

As shown in FIG. 12, the temperature characteristic storage unit 61 of the present embodiment stores a conversion table that associates a temperature detection value with a detection reference value.
FIG. 12 is a diagram illustrating an example of the conversion table in the present embodiment.
As shown in this figure, the temperature characteristic storage unit 61 stores a conversion table in which “temperature detection values” are associated with “detection reference values”. In the example shown in FIG. 12, the “detection reference value” corresponding to “Vtmp1” is “Vref1”, and the “detection reference value” corresponding to “Vtmp2” is “temperature detection value”. "Indicates" Vref2 ".

The conversion table is generated based on the temperature characteristic of the temperature detection value and the temperature characteristic of the detection reference value. For example, the conversion table is based on the above-described temperature conversion table and reference value conversion table, or the above-described equation (6). Generated.
The reference value setting unit 60 of the present embodiment converts the temperature detection value into the detection reference value based on the conversion table for converting the temperature detection value stored in the temperature characteristic storage unit 61 into the detection reference value.

As described above, in the present embodiment, the reference value setting unit 60 associates the temperature detection value and the detection reference value generated based on the temperature characteristic of the temperature detection value and the temperature characteristic of the detection reference value. The detection reference value is generated based on the conversion table to be attached and the temperature detection value.
Thereby, the pressure change measuring apparatus 1 according to the present embodiment can accurately set the detection reference value corresponding to the temperature fluctuation as the detection reference value by a simpler method.

[Fourth Embodiment]
Next, the pressure change measuring apparatus 1 according to the present embodiment will be described with reference to the drawings.
In the present embodiment, a modified example in which the pressure change measuring device 1 includes a sensor chip 100a in which the structures of the reference unit 112 and the temperature sensor unit 121 are different from each other instead of the sensor chip 100 described above will be described.

The configuration of the sensor chip 100a will be described with reference to FIGS.
FIG. 13 is a plan view showing an example of the sensor chip 100a in the present embodiment. FIG. 14 is a cross-sectional view of the sensor chip 100a taken along line AA shown in FIG. FIG. 15 is a cross-sectional view of the sensor chip 100a taken along line BB shown in FIG.
13 to 15, the same components as those in FIGS. 2 to 4 are denoted by the same reference numerals, and the description thereof is omitted.

  As illustrated in FIGS. 13 to 15, the sensor chip 100a includes a differential pressure sensor unit 111, a reference unit 112a, and a temperature sensor unit 121a. The sensor chip 100a in the present embodiment has the same structure as the differential pressure sensor unit 111 and the reference unit 112a, and the temperature sensor unit 121a has the same structure as that of the differential pressure sensor unit 111 and the reference unit 112a. It is different from the sensor chip 100 of the first embodiment in that it is configured.

  The reference part 112a includes a communication opening 11a similar to the differential pressure sensor part 111, and the internal space of the sensor body 2 by the communication opening 11a functions as a cavity 10a (air chamber). The lever portion 4 is fixed to the sensor main body 2 and has a configuration that cannot be bent and deformed.

  The temperature sensor unit 121a has the same configuration as that of the reference unit 112a. The sensor main body 2 (main body unit) having the cavity 10b and the cantilever 3 have the same material and shape, and the sensor main body 2 (main body unit). ), And a lever portion 4a (temperature detection resistance portion) configured to cover the cavity 10b. The lever portion 4a functions as a resistor R5a (detection resistor Rtmp) similar to the resistor R5. Moreover, the temperature sensor part 121a is provided with the same communication opening 11b as the differential pressure sensor part 111, and the internal space of the sensor main body 2 by the communication opening 11b functions as a cavity 10b (air chamber).

In the temperature sensor unit 121a, the gap G6 corresponds to the gap G3 of the reference unit 112a, and the gap G7 corresponds to the gap G4 of the reference unit 112a.
The temperature sensor unit 121a is arranged in a direction rotated 90 degrees in plan view with the reference unit 112a or the differential pressure sensor unit 111.
In this embodiment, the temperature sensor unit 121a includes the cavity 10b, so that not only the temperature characteristics in the thermal equilibrium state but also the heat capacity and the temperature characteristics in the transient state can be brought close to the differential pressure sensor unit 111.

As described above, in the present embodiment, the temperature sensor 120 has the sensor main body 2 (main body portion) having the cavity 10b, the same material and the same shape as the cantilever 3, and the sensor main body 2 (main body portion). ) Of the lever portion 4a (temperature detection resistance portion) configured to cover the cavity 10 and a temperature detection circuit portion 50 that detects a temperature detection value based on a resistance change of the lever portion 4a.
As a result, the pressure change measuring apparatus 1 according to the present embodiment has the temperature characteristics of the temperature sensor unit 121a (temperature characteristics of the resistor R5a) of the differential pressure sensor 110 not only in the thermal equilibrium state but also in the transient state. Since the temperature characteristic (temperature characteristic of the resistor R1) can be approximated, the set reference value can be set with higher accuracy. Therefore, the pressure change measuring apparatus 1 according to the present embodiment can measure the change over time of the pressure of the measurement object with high accuracy even when there is a temperature fluctuation.

  In the present embodiment, the reference portion 112 a has the same cavity 10 a as that of the differential pressure sensor portion 111. Therefore, the temperature characteristic of the resistor R2 (reference resistor Rref) of the reference unit 112a can be made closer to the temperature characteristic of the resistor R1 (detection resistor Rsen) of the differential pressure sensor unit 111. Therefore, the pressure change measuring apparatus 1 according to the present embodiment can further reduce the influence due to the temperature change of the differential pressure sensor 110.

In the example of the present embodiment described above, the example in which the differential pressure sensor unit 111, the reference unit 112a, and the temperature sensor unit 121a are arranged in different directions has been described. However, the differential pressure sensor unit 111 and the reference unit 112a are described. And may be arranged in the same direction as the temperature sensor unit 121a. For example, the differential pressure sensor unit 111, the reference unit 112a, and the temperature sensor unit 121a are arranged in the same direction, and the differential pressure sensor unit 111, the temperature sensor unit 121a, and the reference unit 112a are arranged in the X-axis direction in this order. You may make it do.
As a result, the sensor chip 100a can reduce variations in the resistance R1, the resistance R2, and the resistance R5a due to manufacturing variations depending on the orientation of the manufacturing apparatus.

[Fifth Embodiment]
Next, a pressure change measuring apparatus 1 according to a fifth embodiment will be described with reference to the drawings.
In the present embodiment, a modified example in which the pressure change measuring apparatus 1 includes a sensor chip 100b having a different structure of the temperature sensor unit 121 instead of the sensor chip 100 described above will be described.

The configuration of the sensor chip 100b will be described with reference to FIGS.
FIG. 16 is a plan view showing an example of the sensor chip 100b in the present embodiment. FIG. 17 is a cross-sectional view of the sensor chip 100b along the line BB shown in FIG.
16 and 17, the same components as those in FIGS. 2 and 4 are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIGS. 16 and 17, the sensor chip 100b includes a differential pressure sensor unit 111, a reference unit 112, and a temperature sensor unit 121b. The sensor chip 100b according to the present embodiment is different from the sensor chip 100 according to the first embodiment in that the temperature sensor unit 121b includes a resistor R5b formed by the platinum film 7.
In the temperature sensor part 121b, as shown in FIG. 17, a platinum film 7 having a characteristic as a sensor resistance used for the temperature sensor 120 better than that of the piezoresistor is formed on the upper surface of the doped layer 6. In this embodiment, the platinum film 7 is arranged such that the gap G5 and the gap G6 form a resistor R5b by the platinum film 7. The platinum film 7 is formed to have a long rectangle in the longitudinal direction (Y-axis direction).

As described above, in the present embodiment, the temperature sensor 120 includes the resistor R5 (detection resistor Rtmp) configured by the platinum film 7.
Thereby, the temperature sensor 120 can measure the temperature of the differential pressure sensor 110 more accurately. Therefore, the pressure change measuring apparatus 1 according to the present embodiment can measure the change over time of the pressure of the measurement object with higher accuracy.

[Sixth Embodiment]
Next, a pressure change measuring device 1a according to a sixth embodiment will be described with reference to the drawings.
FIG. 18 is a functional block diagram showing an example of the pressure change measuring device 1a according to the present embodiment.
As illustrated in FIG. 18, the pressure change measuring device 1 a includes a differential pressure sensor 110, a temperature sensor 120, a reference value setting unit 60 a, and an arithmetic processing unit 70.
In this figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

The reference value setting unit 60 a includes a temperature characteristic storage unit 61, a reference value generation unit 62, and a characteristic measurement unit 63.
The present embodiment is different from the first embodiment in that the reference value setting unit 60a includes a characteristic measurement unit 63.

  The characteristic measurement unit 63 measures various temperature characteristics stored in the temperature characteristic storage unit 61. For example, the characteristic measurement unit 63 acquires the set reference value detected by the differential pressure sensor 110 at a predetermined temperature interval, and obtains the temperature characteristics of the set reference value (for example, the above-described reference value conversion table and coefficient information). It is stored in the temperature characteristic storage unit 61. In addition, for example, the characteristic measurement unit 63 acquires the temperature detection value detected by the temperature sensor 120 at a predetermined temperature interval, and displays the temperature characteristic of the temperature detection value (for example, the above-described temperature conversion table or coefficient information). It is stored in the temperature characteristic storage unit 61.

  The characteristic measuring unit 63 may measure the temperature characteristic periodically, or may measure the temperature characteristic by a maintenance mode such as a calibration mode.

As described above, the pressure change measurement device 1a according to the present embodiment includes the characteristic measurement unit 63 that measures various temperature characteristics stored in the temperature characteristic storage unit 61.
As a result, the pressure change measuring apparatus 1a according to the present embodiment allows the pressure of the measurement target to be measured over time even when the temperature characteristics of the differential pressure sensor 110 or the temperature sensor 120 change due to aging (aging). The change can be measured with higher accuracy.

[Seventh Embodiment]
Next, an altitude measuring apparatus 200 according to the seventh embodiment will be described with reference to the drawings.
FIG. 19 is a functional block diagram showing an example of the altitude measuring apparatus 200 according to the present embodiment.
As shown in FIG. 19, the altitude measuring device 200 includes the pressure change measuring device 1 (1 a) described above and an altitude converting unit 210.

The altitude converting unit 210 converts a change in pressure to be measured (for example, an external pressure value Pout) obtained from the pressure change measuring device 1 (1a) into altitude information. For example, since the external pressure value Pout corresponds to the atmospheric pressure, the altitude converting unit 210 outputs altitude information obtained by converting a change in atmospheric pressure into a change in altitude.
As described above, the altitude measuring apparatus 200 according to the present embodiment includes the pressure change measuring apparatus 1 (1a) capable of measuring the above-described temporal change in the pressure of the measurement target with high accuracy. Changes over time can be measured with high accuracy.

The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention.
For example, in the first embodiment, the example in which the differential pressure sensor 110 includes the reference unit 112 has been described. However, the resistor R2 may be configured by an external resistor without including the reference unit 112.
Further, in each of the above embodiments, the reference value setting unit 60 has described the example in which the setting reference value is set every time measurement is performed. However, the setting reference value may be set every predetermined period. However, the setting reference value may be set when the detected differential pressure value is out of a predetermined range.

Further, the various processes in the reference value setting unit 60 described in the first to third embodiments are not limited to the configuration of the sensor chip 100 in the first embodiment, and the fourth and fifth embodiments. Various processes in the reference value setting unit 60 may be applied to the sensor chip 100a (100b) in the embodiment.
In the second embodiment, the example in which the reference value setting unit 60 calculates the setting reference value using a linear function has been described. However, other functions such as a quadratic function may be used. .

In the fifth embodiment, the example in which the resistance by the platinum film 7 is used for the temperature sensor 120 has been described. However, the present invention is not limited to this. For example, a thermistor or a thermocouple is used. May be.
Further, in each of the embodiments described above, the temperature sensor 120 outputs the same detection signal (detection value that varies depending on the temperature) as the differential pressure sensor 110. However, the temperature sensor 120 directly outputs information indicating the temperature. You may make it do. In this case, the temperature characteristic storage unit 61 does not need to store the temperature characteristic of the temperature detection value.

  Further, in each of the above embodiments, the example in which the pressure change measuring device 1 (1a) outputs the external pressure value Pout as information indicating the change in the target pressure has been described, but the present invention is not limited to this. For example, the pressure change measuring device 1 (1a) may output the differential pressure value ΔP as information indicating a change in the target pressure. Further, the pressure change measuring device 1 (1a) may sequentially store information indicating changes in the target pressure.

In the first and fifth embodiments, the example in which the resistor R5 (R5a) is formed in a rectangular shape has been described. However, a rectangular wave shape or a meandering shape is used to increase the resistance value. May be formed. In this case, the power consumption of the pressure change measuring device 1 (1a) can be reduced by increasing the resistance value.
Further, in each of the embodiments described above, an example in which the differential pressure sensor 110 and the temperature sensor 120 supply the same power supply voltage (voltage of the power supply line Vcc) has been described. Different power supply voltages may be supplied depending on the respective characteristics. For example, the power supply voltage supplied to the temperature sensor 120 may be lower than that of the differential pressure sensor 110 to reduce the power consumption of the pressure change measuring device 1 (1a).

The reference value setting unit 60 (60a) and the arithmetic processing unit 70 included in the pressure change measuring device 1 (1a) described above have a computer system therein. And the program for implement | achieving the function of each structure with which the reference value setting part 60 (60a) mentioned above and the arithmetic processing part 70 are equipped is recorded on a computer-readable recording medium, and the program recorded on this recording medium is recorded. You may perform the process in each structure with which the reference value setting part 60 (60a) mentioned above and the arithmetic processing part 70 are provided by making a computer system read and run. Here, “loading and executing a program recorded on a recording medium into a computer system” includes installing the program in the computer system. The “computer system” here includes an OS and hardware such as peripheral devices.
Further, the “computer system” may include a plurality of computer devices connected via a network including a communication line such as the Internet, WAN, LAN, and dedicated line. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. As described above, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

  The recording medium also includes a recording medium provided inside or outside that is accessible from the distribution server in order to distribute the program. Note that the program is divided into a plurality of parts and downloaded at different timings, and each of the constituents included in the reference value setting unit 60 (60a) and the arithmetic processing unit 70 is combined, and each of the divided programs is distributed. The server may be different. Furthermore, the “computer-readable recording medium” holds a program for a certain period of time, such as a volatile memory (RAM) inside a computer system that becomes a server or a client when the program is transmitted via a network. Including things. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  Moreover, you may implement | achieve part or all of the function with which the pressure change measuring apparatus 1 (1a) mentioned above is provided as integrated circuits, such as LSI (Large Scale Integration). Each function described above may be individually made into a processor, or a part or all of them may be integrated into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, in the case where an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology may be used.

DESCRIPTION OF SYMBOLS 1, 1a ... Pressure change measuring apparatus 2 ... Sensor main body 2a ... Bottom wall part 2b ... Peripheral wall part 3 ... Cantilever 3a ... Tip part 3b ... Base end part 4, 4a ... Lever part 5 ... SOI substrate 5a ... Silicon support layer 5b ... Insulating layer 5c ... Silicon active layer 6 ... Dope layer (piezoresistor)
DESCRIPTION OF SYMBOLS 7 ... Platinum film 10, 10a, 10b ... Cavity 11, 11a, 11b ... Communication opening 13 ... Frame part 20 ... Lever main body 21 ... Lever support part 40 ... Differential pressure detection circuit part 41, 51 ... Wheatstone bridge circuit 42, 52 ... Differential amplifier circuit 50 ... Temperature detection circuit unit 60, 60a ... Reference value setting unit 61 ... Temperature characteristic storage unit 62 ... Reference value generation unit 63 ... Characteristic measurement unit 70 ... Calculation processing unit 71 ... Table storage unit 72 ... Internal pressure value storage Unit 73 ... pressure calculation unit 100, 100a, 100b ... sensor chip 110 ... differential pressure sensor 111 ... differential pressure sensor unit 112, 112a ... reference unit 120 ... temperature sensor 121, 121a, 121b ... temperature sensor unit 200 ... altitude measuring device 210 ... Altitude conversion part D1, D2, D3, D4, D5 ... Electrodes R1, R2, R3, R4, R5, R5a, R b, R6, R7, R8 ... resistance G1, G2, G3, G4, G5, G6, G7 ... gap

Claims (11)

A cavity into which a pressure transmission medium for transmitting a pressure to be measured flows, and a communication hole through which the pressure transmission medium flows into and out of the cavity; and a differential pressure between the internal pressure of the cavity and the pressure to be measured A differential pressure sensor for detecting a corresponding differential pressure detection value;
A temperature sensor for detecting a temperature detection value corresponding to the temperature of the differential pressure sensor;
A reference value setting for setting the detection reference value based on the temperature detection value detected by the temperature sensor and a temperature characteristic of a detection reference value indicating the detection value of the differential pressure sensor in a state without the differential pressure And
An arithmetic processing unit that generates information indicating a change in the measurement target pressure based on the detection reference value set by the reference value setting unit and the differential pressure detection value detected by the differential pressure sensor; A pressure change measuring device comprising: The differential pressure sensor is
A sensor body having the cavity;
A cantilever that is plate-shaped extending in one direction from the base end to the tip so as to close the opening surface of the cavity excluding the communication hole, and bends and deforms according to a pressure difference between the inside and the outside of the cavity; ,
The pressure change measuring device according to claim 1, further comprising: a differential pressure detection circuit unit that detects the differential pressure detection value based on a resistance change of the base end portion according to the bending deformation of the cantilever. . The differential pressure sensor has a reference portion having a lever portion configured to be the same material and shape as the cantilever,
The differential pressure detection circuit unit is
The pressure change measuring device according to claim 2, further comprising a Wheatstone bridge circuit having a detection resistor including a resistance of a proximal end portion of the cantilever and a reference resistance including a resistance of a proximal end portion of the lever portion. . The temperature sensor is
A body having a cavity;
A temperature detecting resistor configured to be the same material and shape as the cantilever and to cover the cavity of the main body;
The pressure change measuring device according to claim 2, further comprising: a temperature detection circuit unit that detects the temperature detection value based on a resistance change of the temperature detection resistor unit. The pressure change measuring device according to any one of claims 2 to 4, wherein the cantilever includes a piezoresistor formed of an impurity semiconductor layer at least at the base end. The reference value setting unit includes:
The detection reference value is set based on the temperature detection value, a temperature characteristic of the temperature detection value, and a temperature characteristic of the detection reference value. The pressure change measuring device according to item. The reference value setting unit includes:
Based on the temperature detection value and the temperature characteristic of the temperature detection value, the temperature of the differential pressure sensor is estimated, and based on the estimated temperature of the differential pressure sensor and the temperature characteristic of the detection reference value, The pressure change measuring device according to claim 6, wherein the detection reference value is set. The reference value setting unit includes:
Based on the temperature detection value, the calculation formula for calculating the detection reference value from the temperature detection value generated based on the temperature characteristic of the temperature detection value and the temperature characteristic of the detection reference value, The pressure change measuring device according to claim 6, wherein a detection reference value is calculated. The reference value setting unit includes:
Based on the temperature detection value, a conversion table that is generated based on the temperature characteristic of the temperature detection value and the temperature characteristic of the detection reference value, and associates the temperature detection value with the detection reference value. The pressure change measuring device according to claim 6, wherein the detection reference value is generated. The pressure change measuring device according to any one of claims 1 to 9,
An altitude measuring device comprising: an altitude converting unit that converts a change in the measurement target pressure obtained from the pressure change measuring device into altitude information. A cavity into which a pressure transmission medium for transmitting a pressure to be measured flows, and a communication hole through which the pressure transmission medium flows into and out of the cavity; and a differential pressure between the internal pressure of the cavity and the pressure to be measured A pressure change measurement method using a differential pressure sensor that detects a corresponding differential pressure detection value,
A reference value setting unit detects the temperature detection value detected by a temperature sensor that detects a temperature detection value according to the temperature of the differential pressure sensor, and a detection value indicating the detection value of the differential pressure sensor in the absence of the differential pressure A reference value setting step for setting the detection reference value based on a temperature characteristic of the reference value;
The arithmetic processing unit generates information indicating a change in the measurement target pressure based on the detection reference value set by the reference value setting step and the differential pressure detection value detected by the differential pressure sensor. A pressure change measuring method comprising: an arithmetic processing step.

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