JP5556363B2 - Vacuum gauge - Google Patents

Description

  The present invention relates to a vacuum gauge using a vibrating body, and more particularly to a vacuum gauge capable of measuring a wide range of gas pressures.

  Conventionally, a vacuum gauge (vacuum sensor) that measures the pressure of an atmosphere using a tuning fork type vibrating body is known (see Patent Document 1). The principle of measuring the atmospheric pressure using a tuning fork type vibrator is to vibrate the vibrator and specify the vacuum pressure of the atmosphere from its vibration characteristics.

Conventionally, a vacuum gauge (pressure sensor) that measures a gas pressure from vibration characteristics of a vibrating body by vibrating the vibrating body in two directions is also known (see Patent Document 2).
Conventionally, a vacuum gauge (vacuum sensor) in which a measurable pressure range is expanded using a plurality of vibrating bodies having different areas is also known (see Patent Document 3).

Japanese Patent Laid-Open No. 62-137533 Japanese Patent Laid-Open No. 08-338776 (paragraph in FIG. 5, 0059) JP 2008-093401 A

(A) Limitation of measurable pressure range in vacuum gauge using vibrating body:
In a vacuum gauge using a vibrating body, generally, the Q value of the vibrating body (one of the vibration characteristics of the vibrating body) is inversely proportional to the gas pressure P. The Q value of the vibrating body is related to the gas pressure P, ω _R is the resonance angular frequency [rad / s] of the vibrating body, m is the mass [kg] of the vibrating body, and S is the area in the translation direction [ m ² ], R is the gas constant [8.314 J / k · mol], T is the temperature [K], M is the mass of the gas molecule [kg / mol], E is Young's modulus [Pa], and I is the moment of inertia of the cross section. [m ⁴ ], l: Effective beam length [m] (= beam length + weight 1 side / 2), it can be expressed as the following equation (1).

In addition, said Formula (1) is materialized when a vibrating body is a cantilever. Thereby, the gas pressure can be indirectly evaluated by measuring the Q value of the vibrating body. However, the practical measurement range of the Q value of a vacuum gauge using a vibrating body is about 100 to 100,000, and there is a problem that the pressure range that can be measured is limited to about three digits.
(B) Problems in the vacuum gauges of Patent Documents 1 to 3 described above:
(A) The vacuum gauge of Patent Document 1 vibrates a pair of parallel flat plate-like vibrating bodies forming one tuning fork type vibrator in a direction perpendicular to the flat plate surface, and specifies the vacuum pressure of the atmosphere from the vibration characteristics. Therefore, there is a problem that the pressure range that can be measured with one vacuum gauge is narrow.

(B) Although the vacuum gauge of patent document 2 has expanded the pressure range which can be measured with one vacuum gauge so that a vibrating body can be vibrated in two directions, there exist the following problems. .
(B1) Since the vacuum gauge of Patent Document 2 employs a configuration in which the vibration direction of the vibrating body is switched according to the pressure of the gas to be measured, measurement is discontinuous when the vibration direction of the vibrating body is switched.

    (B2) The vacuum gauge of Patent Document 2 employs a configuration in which two electrodes for vibrating the vibrating body in two directions are separately provided and the vibration direction of the vibrating body is switched in accordance with the gas pressure to be measured. This complicates the circuit configuration.

(C) Although the vacuum gauge of patent document 3 has expanded the pressure range which can be measured with one vacuum gauge using the several vibrating body from which an area differs, there exist the following problems.
(C1) Since the vacuum gauge of Patent Document 3 employs a configuration in which a vibrating body to be used is selected according to the pressure of the gas to be measured, measurement is discontinuous when the vibrating body to be used is switched.

(C2) In the vacuum gauge of patent document 3, since the structure which selects the vibrating body to be used according to the pressure of the gas to measure is employ | adopted, a circuit structure becomes complicated.
(C3) In the vacuum gauge of patent document 3, since the mass of the vibrating body is increased by increasing the area, the effect of increasing the area is offset. This point will be further described.

FIG. 31 shows an example of design values of the vacuum gauge designed in accordance with the configuration example of the vacuum gauge shown in Patent Document 3 (the area ratio of the vibrating body in design I and design II is 4: 1). 32 is a diagram showing the relationship between the gas pressure P and the Q value of the vibrating body at the design values shown in FIG. As shown in FIG. 32, the effect of increasing the area of the weight of the vibrating body is small. Further, if the area is increased, there is a possibility that the vibrating body and the vibration detection electrode come into contact with each other due to the influence of the warping of the vibrating body. Therefore, the area of the vibrating body cannot be increased beyond a certain value.
(C) In order to solve the above-described problems, the present invention provides a vacuum gauge that can measure the pressure of a wide range of gas without making the measurement discontinuous with a single vacuum gauge and has a simplified circuit configuration. The purpose is to provide.

In order to solve the above problems, the vacuum gauge of the present invention is provided with a plurality of pressure measuring units that measure the atmospheric pressure from the vibration characteristics of the vibrating body held in a resonance state, and the pressure measuring units have a common atmosphere. In a vacuum gauge for measuring pressure, the pressure ranges that can be measured by each pressure measuring unit are made different, and the pressure ranges are partially overlapped, and the entire pressure measurement range of the vacuum gauge in, addition the output signal of the pressure measuring unit for the same atmosphere, multiplication or division operations to be characterized in that a calculation unit for calculating a pressure measurement signal (the invention of claim 1).

  According to the first aspect of the present invention, a plurality of pressure measuring units for measuring the pressure of a common atmosphere are provided, the pressure ranges that can be measured by each pressure measuring unit are made different, and a part of the pressure range is provided. By being configured to overlap, the pressure of a wider range of gas can be measured with one vacuum gauge.

According to the invention of the first aspect, in the entire region of the pressure measurement range of the gauge, it adds the output signal of the pressure measuring unit for the same atmosphere, calculating the pressure measurement signal by multiplying or division operations As a result, the pressure of a wide range of gases can be measured without making the measurement discontinuous with one vacuum gauge.

According to the invention of the first aspect, it adds the output signal of the pressure measurement section may be Sonaere the only the calculator multiplication or division operation to calculate the pressure measurement signal, the pressure of the gas to be measured Accordingly, the configuration for selecting the pressure measuring unit is not necessary, and the circuit configuration of the vacuum gauge is further simplified.

In vacuum gauge described above Symbol claim 1, based on the characteristic data of the relationship between the arithmetic value and the pressure value that by the prior SL calculating section, a pressure measurement signal calculated by said calculation unit to a pressure value conversion, a configuration in which closed the pressure conversion section for outputting as a pressure value (claim 2).

According to the invention described in claim 2, by the output signal a signal based on the pressure value obtained by the pressure converter unit, pressure pressure range between overlap that can be measured by the pressure measuring section It is possible to correct a non-linearity in the vicinity of the region and obtain a pressure measurement signal having a uniform linearity over the entire region of the pressure measurement range of the vacuum gauge.

3. The vacuum gauge according to claim 2 , wherein the pressure conversion unit performs conversion from a combination calculation value to a pressure value at the time of actual measurement by a conversion unit including a storage unit storing a data table of the characteristic data. (Claim 3 ).

3. The vacuum gauge according to claim 2 , wherein the pressure conversion unit uses a conversion unit including a storage unit that stores a relational expression approximately obtained from the curve of the characteristic data, from a combination calculation value at the time of actual measurement. It is set as the structure which converts into a pressure value (Claim 4 ).

The vacuum gauge as claimed in any one of the above claims 1 to 4, the drive to generate a vibrating body, a vibrating electrode portion driven by electrostatic force vibration member, a driving signal for vibrating the vibrator A pressure generation unit that measures the pressure of the atmosphere from the vibration characteristics of the vibration body by holding the vibration body in a resonance state by applying the drive signal to the excitation electrode unit. A plurality of the vibrators in a common atmosphere in the vacuum gauge, different pressure ranges that can be measured by the vibrators, and a part of the pressure range. constructed by overlapping the corresponding to each vibrator provided a plurality of the pressure measurement section, the entire area of the pressure measurement range of the gauge, adds the output signal of the pressure measuring unit for the same atmosphere, Multiplication or division Operation to a structure in which a calculation unit for calculating a pressure measurement signal (the invention of claim 5).

According to the fifth aspect of the present invention, a plurality of vibrators having different pressure ranges that can be measured in a common atmosphere in a vacuum gauge are provided, and the pressure ranges are partially overlapped. A single vacuum gauge can measure a wider range of gas pressures.

According to the fifth aspect of the present invention, the output signals of the respective pressure measurement units for the same atmosphere are added and multiplied in the entire range of the pressure measurement range of the vacuum gauge in a state where a plurality of vibrators are vibrated simultaneously. or by division operation to calculate the pressure measurement signal, without the measurement at one of the gauge becomes discontinuous, it becomes possible to measure the pressure in the broad range of gases.

According to the invention of the claim 5, adds the output signal of the pressure measurement section may be Sonaere the only the calculator multiplication or division operation to calculate the pressure measurement signal, the pressure of the gas to be measured Accordingly, the configuration for selecting the vibrating body to be used is not necessary, so that the circuit configuration of the vacuum gauge is further simplified.

In the vacuum gauge according to claim 5 , each of the vibrators has a configuration in which a pressure range that can be measured varies depending on at least one of a thickness, a length of a beam, a material, or an area (the invention of claim 6 ). ).

The vacuum gauge according to claim 5 or 6 , wherein the pressure measurement unit includes a vibration detection unit that detects vibration of the vibrating body, and the drive signal generation unit is a detection signal of the vibration detection unit. The drive signal for exciting the vibrating body is generated by changing the phase of the detection signal and amplifying the detection signal (invention of claim 7 ) .
The vacuum gauge according to claim 7 , wherein the pressure measurement unit includes a vibration electrode unit including a pair of vibration electrodes disposed along the vibration direction on both sides of the vibration body, and includes a vibration detection unit. A vibration detection unit comprising: a phase shift circuit that changes the phase of the detection signal; an amplifier that amplifies the output signal of the phase shift circuit; and an inversion circuit that inverts the phase of the output signal of the amplifier. The resonance state of the vibrating body is maintained by applying the output signals of the inverting circuit and the amplifier to the set of excitation electrodes, respectively, as drive signals having opposite phases based on the detection signals of 8 invention).

The vacuum gauge according to any one of claims 1 to 4 , wherein the vacuum gauge is configured to vibrate in a first vibration direction and a second vibration direction orthogonal to the first vibration direction. Based on the vibration body, the excitation electrode section that drives the vibration body by electrostatic force, the vibration detection section that detects the vibration of the vibration body, and the detection signal of the vibration detection section, the phase of the detection signal is changed. A drive signal generation unit that generates a drive signal for exciting the vibrating body by amplification, applying the drive signal to the excitation electrode unit to hold the vibrating body in a resonance state, A vacuum gauge that measures the pressure of the atmosphere from the vibration characteristics of a vibrating body, wherein the vibrating electrode section includes first and second applied forces for vibrating the vibrating body in first and second vibration directions, respectively. A vibration electrode unit, and as the vibration detection unit, the vibration The first and second vibration detectors detect vibrations in the first and second vibration directions, respectively, and apply a drive signal based on the detection signal of the first vibration detector to the first excitation electrode unit. By doing so, a first pressure measuring unit that measures the pressure by vibrating the vibrating body in the first vibration direction, and a drive signal based on the detection signal of the second vibration detecting unit is sent to the second excitation electrode unit. And a second pressure measuring unit that measures the pressure by vibrating the vibrating body in a second vibration direction, and the first and second pressure measuring units cause the vibrating body to be first. And simultaneously oscillating in the second vibration direction to simultaneously measure each pressure in each vibration direction, different pressure ranges that can be measured by the first and second pressure measuring units, and and configure part by overlapping the pressure range, prior In the entire region of the pressure measurement range of the gauge, adds the output signals of said first and second pressure measuring unit for the same atmosphere, configuration and provided with a calculation unit for calculating a pressure measurement signal by multiplying or division operations (Invention of claim 9 )

According to the ninth aspect of the present invention, the vibration body is vibrated in both the first and second vibration directions having different measurable pressure ranges, and the pressure is measured, and the pressure ranges are partially overlapped. By comprising, it is possible to extend the pressure range measurable with one vacuum gauge.

According to the ninth aspect of the present invention, the vibration body is vibrated simultaneously in the first and second vibration directions, and each pressure measurement in each vibration direction is performed simultaneously, whereby the vibration direction is switched depending on the gas pressure. As a result, it is possible to eliminate the generation of unmeasurable time during switching, and it is possible to continuously measure a wide range of pressures.

According to the ninth aspect of the present invention, since a circuit for switching the vibration direction of the vibrating body is not required, the circuit can be simplified.
According to the ninth aspect of the present invention, the vibrating body is vibrated simultaneously in the first and second vibration directions by the first and second pressure measuring units, and each pressure measurement in each vibration direction is performed simultaneously. in a state in which there, in the entire region of the pressure measurement range of the gauge, the output signal of the pressure measuring unit for the same atmosphere addition, by multiplication or division operation to calculate the pressure measurement signal, one at a vacuum gauge It becomes possible to measure a wide range of gas pressures without making the measurement discontinuous.

According to the invention of the claim 9, adds the output signal of the pressure measurement section may be Sonaere the only the calculator multiplication or division operation to calculate the pressure measurement signal, the pressure of the gas to be measured Accordingly, the configuration for selecting the pressure measuring unit is not necessary, and the circuit configuration of the vacuum gauge is further simplified.

10. The vacuum gauge according to claim 9 , wherein the first excitation electrode unit is composed of first and second excitation electrodes disposed along both sides of the vibrating body along a first vibration direction. A set of excitation electrodes, and the second excitation electrode section includes a set of third and fourth excitation electrodes disposed along the second vibration direction on both sides of the vibrating body. The drive signal generation unit includes first and second phase shift circuits that change the phases of the detection signals of the first and second vibration detection units, and the first and second phase shift circuits. First and second amplifiers for amplifying the respective output signals of the phase shift circuit, and first and second inversion circuits for inverting the phases of the output signals of the first and second amplifiers, respectively. Having a negative phase drive signal based on the detection signal of the first vibration detector By applying the output signals of the first inverting circuit and the first amplifier to the first and second excitation electrodes, respectively, the resonance state of the vibrating body in the first vibration direction is maintained. In addition, the output signals of the second inverting circuit and the second amplifier are supplied to the third and fourth excitation electrodes, respectively, as drive signals of opposite phase based on the detection signal of the second vibration detection unit. By applying, the resonance state in the second vibration direction of the vibrating body is maintained (invention of claim 10 ).

The vacuum gauge as claimed in any one of the above claims 7 to 10, wherein the drive signal generating unit, as the voltage of the drive signal is constant, the signal for changing the phase of the detection signal of the vibration detection unit The pressure measurement unit is configured to measure the pressure based on the magnitude of the detection signal of the vibration detection unit (invention of claim 11 ).

The vacuum gauge according to any one of claims 7 to 10 , wherein the drive signal generation unit detects the detection signal of the vibration detection unit such that the magnitude of the detection signal of the vibration detection unit is constant. The gain of amplification with respect to a signal whose phase is changed is adjusted, and the pressure measurement unit measures pressure based on the voltage of the drive signal (invention of claim 12 ).

The vacuum gauge according to any one of claims 7 to 12 , further comprising an initial excitation signal source that outputs an initial excitation signal having a frequency corresponding to a natural frequency of the vibrating body, and at the time of initial driving of the vibrating body, Instead of the drive signal based on the detection signal of the vibration detection unit, an initial drive signal based on the initial excitation signal is applied to the excitation electrode unit (invention of claim 13 ).

The vacuum gauge according to any one of claims 7 to 13 , wherein the vibration detecting unit detects vibration of the vibrating body by detecting a capacitance between the vibrating body and a detection electrode. It is set as the thing (invention of Claim 14 ).

  According to the present invention, it is possible to provide a vacuum gauge that can measure a wide range of gas pressures without making measurement discontinuous with a single vacuum gauge and whose circuit configuration is simplified.

It is a top view which shows the structural example of the structure which comprises the mechanism part of the vacuum gauge which concerns on 1st Embodiment of this invention. It is a side view of the structure shown in FIG. It is a figure which shows an example of the design value of the vibrating body which concerns on 1st Embodiment of this invention. It is a figure which shows the relationship between Q value in the design value of the vibrating body shown in FIG. 3, and the pressure P of gas. It is a block diagram which shows the circuit structural example of the vacuum gauge which concerns on 1st Embodiment of this invention. It is a figure which shows an example from which the design value of the vibrating body which concerns on 1st Embodiment of this invention differs. FIG. 7 is a diagram showing a relationship between the amplitude of the vibrating body and the gas pressure P when the amplifier gain is adjusted so that the drive voltage is constant in the vibrating body having the design value shown in FIG. 6. 7 is a diagram illustrating a relationship between a driving voltage and a gas pressure P when an amplifier gain is adjusted so that the amplitude of the vibrating body is constant in the vibrating body having the design value illustrated in FIG. 6. FIG. It is a figure which illustrates the relationship between the amplitude of a vibrating body and atmospheric pressure in 1st Embodiment of this invention. It is a figure which illustrates the relationship between the output voltage of the capacity voltage conversion circuit in 1st Embodiment of this invention, and the pressure of atmosphere. It is a figure which illustrates the relationship between the output value of the calculating part (consisting of an adder) in Example 1 of this invention, and the pressure of an atmosphere. It is a figure which illustrates the relationship between the output value of the calculating part (consisting of a multiplier) in Example 2 of this invention, and the pressure of an atmosphere. It is a figure which illustrates the relationship between the output value of the calculating part (consisting of a divider) in Example 3 of this invention, and the pressure of an atmosphere. It is a top view which shows the example of a different structure of the structure which comprises the mechanism part of the vacuum gauge which concerns on 1st Embodiment of this invention. It is a side view of the structure shown in FIG. It is a block diagram which shows the example of a different circuit structure of the vacuum gauge which concerns on 1st Embodiment of this invention. It is a block diagram which shows the further different circuit structural example of the vacuum gauge which concerns on 1st Embodiment of this invention. It is a figure which shows the further different example of the design value of the vibrating body which concerns on 1st Embodiment of this invention. It is a figure which shows the relationship between the gas pressure P in the specific example 1 of the design value of the vibrating body shown in FIG. 18, and the Q value of a vibrating body. It is a figure which shows the relationship between the gas pressure P and the Q value of a vibrating body in the specific example 2 of the design value of the vibrating body shown in FIG. It is a figure which shows the relationship between the gas pressure P in the specific example 3 of the design value of the vibrating body shown in FIG. 18, and the Q value of a vibrating body. It is a figure which shows the relationship between the gas pressure P in the specific example 4 of the design value of the vibrating body shown in FIG. 18, and the Q value of a vibrating body. It is a figure which shows the relationship between the gas pressure P and the Q value of a vibrating body in the specific example 5 of the design value of the vibrating body shown in FIG. It is a top view which shows the structural example of the structure which comprises the mechanism part of the vacuum gauge which concerns on 2nd Embodiment of this invention. It is a side view of the structure shown in FIG. It is a figure which shows an example of the design value of the vibrating body which concerns on 2nd Embodiment of this invention. It is a figure which shows the relationship between the gas pressure P in the design value of the vibrating body shown in FIG. 26, and the Q value of a vibrating body. It is a block diagram which shows the circuit structural example of the vacuum gauge which concerns on 2nd Embodiment of this invention. FIG. 27 is a diagram showing the relationship between the amplitude of the vibrating body and the gas pressure P when the amplification gain is adjusted so that the drive voltage is constant in the first vibration direction of the vibrating body having the design value shown in FIG. 26. FIG. 27 is a diagram illustrating a relationship between a driving voltage and a gas pressure P when the amplification gain is adjusted so that the amplitude of the vibrating body is constant in the first vibration direction of the vibrating body having the design value illustrated in FIG. 26. It is a figure which shows an example of the design value of the vacuum sensor designed according to the structural example of the vacuum gauge shown by patent document 3. FIG. It is a figure which shows the relationship between the gas pressure P in the design value shown in FIG. 31, and the Q value of a vibrating body.

Hereinafter, embodiments of the present invention will be described in detail. About the same component, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted. In addition, this invention is not limited to the following embodiment, In the range which does not change the summary, it can implement suitably.
[First Embodiment]
The vacuum gauge according to the first embodiment of the present invention constantly vibrates a plurality of vibrating bodies that have different measurable pressure ranges and partially overlap each other, and output signals of each pressure measuring unit corresponding to each vibrating body Is calculated based on the combination calculation value, and the output signal of the calculation processing unit based on the combination calculation value is used as the pressure measurement signal of the vacuum gauge.
(B) Structure of the structure that forms the mechanism of the vacuum gauge:
FIG. 1 is a plan view showing a configuration example of a structure that forms a mechanism part of a vacuum gauge according to the first embodiment of the present invention, and FIG. 2 is a side view of the structure shown in FIG. In FIG. 1 and FIG. 2, the structure constituting the mechanism of the vacuum gauge includes a vibrating body 4 comprising a weight 1, a beam 2 and a vibrating body fixing portion 3, a vibrating electrode 5 for vibrating the vibrating body 4, and a vibrating body. 4 is composed of a vibration detection electrode 6 for detecting vibrations.
(B) Relationship between the shape of the vibrating body, the Q value of the vibrating body and the gas pressure P:
Next, the relationship between the shape of the vibrating body 4, the Q value of the vibrating body 4, and the gas pressure P will be described. The vibrating body 4 receives a resistance force due to collision of gas molecules. In the molecular flow region, the resistance force by the gas molecules is directly proportional to the gas pressure P. As the gas pressure decreases, the resistance force that the vibrating body 4 receives from the gas molecules decreases, so the Q value (resonance sharpness) of the vibrating body increases. However, the vibrating body 4 has a specific Q value Q _E and never exceeds the specific Q value Q _E. That is, the lower limit of the pressure of the gas that can vibrator 4 is measured, meant to be limited by the specific Q value Q _E.

The relationship between the pressure P of the Q value and gas of the vibrating member 4, the natural frequency of the vibration member 4 to f _r, the weight of the mass m, the area which receives the resistance force of the gas to S, the gas and R constant, the T If the temperature and M are masses per 1 mol of gas molecules, the Q value of the vibrating body 4 is expressed by the following equation (2):

It can be expressed as. Note that the above expression (2) has substantially the same content as the above-described expression (1) because it has a relationship of f _r = ω _R / 2π.
(C) Examples of design values of the vibrator:
FIG. 3 is a diagram illustrating an example of the design value of the vibrating body according to the first embodiment of the present invention, and FIG. 4 illustrates the relationship between the Q value and the gas pressure P in the design value of the vibrating body illustrated in FIG. It is a figure which shows a relationship. The table shown at the bottom of FIG. 3 shows design (a) and design (b) as design examples. As shown in FIG. 4, the gas pressure (measurable pressure range) that can be measured in the case of design (a) is about 0.1 Pa to about 100 Pa (“evaluation range of design (a)” in FIG. 4). In addition, the gas pressure (measurable pressure range) that can be measured in the case of the design (b) is about 3 Pa to about 3000 Pa (“evaluation range of the design (b)” in FIG. 4). The pressure region of “about 3 Pa to about 100 Pa” in FIG. 4 is an overlap pressure region where the measurable range of the vibrating body of design (a) and the measurable range of the vibrating body of design (b) overlap. It has become.

Thus, the gas pressure range (measurable pressure range) that can be measured according to the shape of the vibrating body can be arbitrarily designed, and the overlap pressure region can also be arbitrarily designed. In addition, the natural frequency of each vibration body of the design (a) and the design (b) shown in FIG. 3 is about 320 Hz and about 16.5 kHz, respectively, when the material of each vibration body is silicon.
(D) Circuit configuration of vacuum gauge:
Next, the circuit configuration of the vacuum gauge according to the first embodiment of the present invention will be described. FIG. 5 is a block diagram showing an example of a circuit configuration of the vacuum gauge according to the first embodiment of the present invention. Since the configuration includes two vibrating bodies in one vacuum gauge, the figure is divided into upper and lower parts. ing.

The circuit configuration example of FIG. 5 corresponds to the structure of the configuration example shown in FIGS. 1-2, and includes a vibrating body 24, a weight 25, a beam 26, and a weight 21, a beam 22, and a vibrating body fixing portion 23. The vibration body 28 composed of the vibration body fixing portion 27, the excitation electrodes 29 and 30, the vibration detection electrodes 31 and 32 for detecting the vibration of the vibration bodies 24 and 28, and the capacitance between the weight 21 and the vibration detection electrode 31 Capacitance-voltage conversion circuit 33 that outputs voltage V _A according to change, capacitance-voltage conversion circuit 34 that outputs voltage V _B according to change in capacitance between weight 25 and vibration detection electrode 32, capacitance-voltage conversion Phase shift circuits 35 and 36 for changing the phases of the signals V _A and V _B output from the circuits 33 and 34, amplifiers 37 and 38 for amplifying the outputs of the phase shift circuits 35 and 36, and amplitudes of the vibrators 24 and 28 Switch circuit 39 and 40 for switching the drive signal, and the initial excitation signal for the vibrators 24 and 28. Sources 41 and 42, combined by calculating the arithmetic unit 91 the output signals V _A and V _B of the capacitance-voltage conversion circuit 33 and 34, the combination calculation value (operation signal V _PO) to a pressure value by the pressure converting unit 92 It comprises an arithmetic processing unit 93 that converts and outputs the pressure measurement signal V _P of the vacuum gauge.

As shown in FIG. 5, the vibrator 24, the excitation electrode 29, the vibration detection electrode 31, the capacitance voltage conversion circuit 33, the phase shift circuit 35, the amplifier 37, the drive signal switching circuit 39, and the initial excitation A pressure measurement unit 81A is configured by the signal source 41, and an output signal V _A of the capacitance-voltage conversion circuit 33 is an output signal as the pressure measurement unit 81A. In addition, the pressure measuring unit 81B includes the vibrating body 28, the excitation electrode 30, the vibration detection electrode 32, the capacitance voltage conversion circuit 34, the phase shift circuit 36, the amplifier 38, the drive signal switching switch circuit 40, and the initial excitation signal source 42. There is constituted, the output signal V _B of the capacitance-voltage conversion circuit 34 is an output signal of the pressure measurement section 81B.

  In addition, the above-described combination calculation by the calculation unit 91 of the calculation processing unit 93 is performed in a state where the vibration measuring bodies 24 and 28 are constantly vibrated and the pressure measurement units 81A and 81B are operated. Is done in the region. More specifically, as the calculation unit 91, for example, a calculation unit 91a composed of an adder, a calculation unit 91m composed of a multiplier, a calculation unit 91d composed of a divider, and the like described in the first to third embodiments will be described. Can be applied.

The pressure converter 92 of the processing unit 93, based on the characteristic data of the relationship between the combination calculated value (the calculation signal V _PO) and the pressure value by the calculation unit 91, the combination calculated value in a time of actual measurement (calculation signal V _PO ) To a pressure value.

In FIG. 5, the arithmetic processing unit 93 includes a pressure conversion unit 92 on the output side of the calculation unit 91, and a signal based on the pressure value obtained by the pressure conversion unit 92 is output as a pressure measurement signal V _P of the vacuum gauge. However, the present invention is not limited to the above configuration. That is, in the present invention, basically, a wide pressure range from the lower limit side of the measurable pressure range of the low pressure region pressure measurement unit to the upper limit side of the measurable pressure range of the high pressure region pressure measurement unit (pressure measurement of the vacuum gauge). In the entire range), a measurement signal that changes continuously according to the pressure and has a one-to-one relationship with the pressure is obtained, and based on this measurement signal, the atmospheric pressure can be set within a wide pressure range (vacuum pressure range). It suffices if measurement can be continuously performed over the entire measurement range. For this reason, in the present invention, depending on the signal form required as the pressure measurement signal of the vacuum gauge, for example, the arithmetic processing unit 93 does not include the pressure conversion unit 92, and the calculation signal _VPO from the calculation unit 91 is used as the vacuum gauge. It can also be configured to output as a pressure measurement signal.
(E) Operation of pressure measurement unit in vacuum gauge:
(A) Next, the operation of each pressure measuring unit in the vacuum gauge according to the first embodiment of the present invention will be described with reference to the circuit configuration example of FIG. In FIG. 5, when the vibrating bodies 24 and 28 are initially excited, the drive signal switching switch circuits 39 and 40 are connected to A and B, and D and E, respectively. A signal having a frequency corresponding to the natural frequency of the vibrating bodies 24 and 28 output from 41 and 42 is applied to the vibrating electrodes 29 and 30, and the vibrating bodies 24 and 28 are excited. The initial excitation signal sources 41 and 42 are used only during initial driving, and after the vibrating bodies 24 and 28 start to vibrate, the drive signal switching switch circuits 39 and 40 are switched, and A, C, D, respectively. F is connected. The phases of the signals output from the capacity voltage conversion circuits 33 and 34 are shifted by the phase shift circuits 35 and 36, applied to the excitation electrodes 29 and 30 via the amplifiers 37 and 38, and the resonance state is maintained. The drive signal switching circuits 39 and 40 operate so as to switch connections according to the amplitudes of the vibrating bodies 24 and 28, respectively, as described above. For example, the amplitude of the vibrating bodies 24 and 28, That is, the control for the switch circuit (not shown) that the magnitudes of the output signals V _A and V _B of the capacitive voltage conversion circuits 33 and 34 output according to the displacement of the vibrating bodies 24 and 28 have reached a preset value. And at the detection timing, a switching signal from the B side to the C side and a switching signal from the E side to the F side are given from the switch circuit control unit to the drive signal switching switch circuits 39 and 40, respectively. It can be carried out.

(B) The pressure measurement operation method of each pressure measurement unit 81A, 81B is configured to adjust the gains of the amplifiers 37, 38 so that the voltage of the drive signal applied to the excitation electrodes 29, 30 is constant (hereinafter referred to as “ In other words, the amplitude of the vibrating bodies 24 and 28 corresponding to the Q values of the vibrating bodies 24 and 28, that is, the respective signals V _A output from the capacity voltage conversion circuits 33 and 34 , V _B changes in size. Therefore, the signals V _A and V _B output from the capacity voltage conversion circuits 33 and 34 can be used as output signals as the pressure measuring units 81A and 81B.

In addition, if each signal V _A , V _B is converted into each Q value and further converted into gas pressure P, pressure measurement in each measurable pressure range of the pressure measuring units 81A, 81B can be performed. it can. For example, when the designs (a) and (b) which are the design examples shown in FIG. 3 are used for the vibrating bodies 24 and 28, the output of the capacitive voltage conversion circuit 33 (the output of the pressure measuring unit 81A) is in the range of 0.1 Pa to 100 Pa. By measuring the gas pressure from the magnitude of the signal V _A ) and from the magnitude of the output of the capacitive voltage conversion circuit 34 (output signal V _B of the pressure measuring unit 81B) in the region of 3 Pa to 3000 Pa, 0.1 Pa It is possible to measure the pressure of a wide range of gas from 3 to 3000 Pa. Further, the conversion from each output signal (amplitude of the vibrating body) of each of the capacitance / voltage conversion circuits 33 and 34 into each pressure value can be directly performed without passing through the Q value.

Further, when the vibrating body 28 in the configuration example of FIG. 5 is a design value shown in FIG. 6 and the material is a silicon vibrating body, for example, in the vibration direction along the wide surface of the weight 1, the excitation electrode 30 is used. When the gain of the amplifier 38 is adjusted so that the voltage of the drive signal applied to is constant, the relationship between the magnitude of the output signal V _B of the capacitive voltage conversion circuit 34 (amplitude of the vibrating body) and the pressure value is As shown in FIG. 7, in the high pressure region (about 10 Pa or more), the amplitude is approximately inversely proportional to the pressure, and on the low pressure side, the amplitude is saturated toward the maximum limit value. Here, FIG. 6 shows an example in which the design values of the vibrating body according to the first embodiment of the present invention are different.

As described above, according to the present invention, the output signals V _A and V _{B of the} pressure measuring units 81A and 81B are combined and calculated by the calculation unit 91, and the output signal of the calculation processing unit 93 based on the combination calculation value is vacuumed. In the case of outputting each pressure measurement signal based on the output signal (amplitude of the vibrating body) of each capacitive voltage conversion circuit in the above-described constant driving voltage method as a vacuum gauge, Conversion from the output signal of each capacitance-voltage conversion circuit to each pressure value can be performed, for example, as follows. That is, the characteristic data of the relationship between the magnitudes of the output signals V _A and V _B (amplitude of the vibrating body) of the capacitance-voltage conversion circuits 33 and 34 and the pressure values are acquired. Then, the conversion means having a storage unit storing the data table of the characteristic data converts the output signals V _A and V _B (amplitude of the vibrating body) at the actual measurement into the pressure values PA and PB. Each output signal V _A , V _B (vibrating body) at the time of actual measurement can be obtained by a conversion means having a storage unit storing a relational expression approximately obtained from the curve of the characteristic data. It is also possible to adopt a configuration in which the pressure values PA and PB are converted.

(C) In addition, the pressure measurement operation method of each pressure measuring unit 81A, 81B is determined according to the amplitude of the vibrating bodies 24, 28, that is, the capacitance voltage conversion circuits 33, 34 output according to the displacement of the vibrating bodies 24, 28. _A configuration in which the gains of the amplifiers 37 and 38 are respectively adjusted so that the magnitudes of the output signals V _A and V _B (the amplitude of the vibrating body) are constant (hereinafter also referred to as “constant amplitude method”) may be employed. In this case, the voltage of each drive signal applied to the excitation electrodes 29 and 30 from the amplifiers 37 and 38 changes corresponding to each Q value of the vibrating bodies 24 and 28, so the voltage of each drive signal is measured by pressure. Each output signal as the parts 81A and 81B can be used.

  If the voltage of each of the drive signals is converted into each Q value and further converted into the gas pressure P, the pressure measurement in each measurable pressure range of the pressure measuring units 81A and 81B can be performed. . Moreover, the conversion from the voltage of each drive signal to each pressure P value can be directly performed without passing through the Q value.

Further, when the vibrating body 28 in the configuration example of FIG. 5 is, for example, the design value shown in FIG. 6 and the material is a vibrating body made of silicon, in the vibration direction along the wide surface of the weight 1, a capacitive voltage conversion circuit. The relationship between the magnitude of the drive signal (drive voltage) and the pressure value when the gain of the amplifier 38 is adjusted so that the magnitude of the output signal V _B of 34 (the amplitude of the vibrating body) is constant is shown in FIG. In the high voltage region (about 10 Pa or more) as shown in FIG. 5, the drive voltage is approximately proportional to the pressure, and on the low voltage side, the drive voltage decreases so as to saturate toward the minimum limit value.

As described above, in the present invention, the output signals V _A and V _{B of the} pressure measuring units 81A and 81B are combined and calculated by the calculation unit 91, and the output signal of the calculation processing unit 93 based on the combination calculation value is vacuum-processed. However, if each pressure measurement signal based on the voltage of each drive signal in the constant amplitude method is also output as a vacuum gauge, the voltage of each drive signal is changed to each pressure value. This conversion can be performed, for example, as follows. That is, the characteristic data of the relationship between the voltage of each drive signal and each pressure value is acquired. The conversion means having a storage unit storing a data table of the characteristic data can be configured to convert the voltage of each drive signal into each pressure value at the time of actual measurement. It is also possible to adopt a configuration for converting the voltage of each drive signal into each pressure value at the time of actual measurement by a conversion means having a storage unit that stores a relational expression approximately obtained from a curve.

(D) Here, in the circuit configuration example of FIG. 5, the output signals V _A and V _{B of the} pressure measuring units 81A and 81B input to the computing unit 91 are converted into capacitive voltage conversion in accordance with the driving voltage constant method. Although the configuration of the output signals (amplitude of the vibrating body) of the circuits 33 and 34 is shown, the present invention is not limited to the configuration described above, and is input to the arithmetic unit 91 in accordance with the constant amplitude method. Alternatively, the output signals V _A and V _{B of the} pressure measuring units 81A and 81B may be signals based on the voltages of the drive signals.

(E) The circuit configuration example in FIG. 5 corresponds to a pressure measurement method in which all the vibrating bodies are constantly vibrated regardless of the gas pressure.
Further, in the description of the operation of the pressure measuring unit described above, as shown in the table of FIG. 3, two vibrators having different vibrator thickness, beam length, vibrator body material or area are used. In the case of the above, similarly, by using three or more vibrators having at least one of the thickness of the vibrator, the length of the beam, the material or the area of the vibrator, the gas in a wider area can be used. The pressure can be measured.
(F) Configuration and operation of the calculation unit in the vacuum gauge:
Examples of pressure measurement characteristics of the two pressure measurement units 81A and 81B corresponding to the two vibrators 24 and 28 having different measurable pressure ranges are shown in FIGS.

FIG. 9 is a diagram illustrating the relationship between the amplitude of the vibrating body and the pressure of the atmosphere in the first embodiment of the present invention, and illustrates the amplitude-pressure characteristics of the vibrating bodies 24 and 28.
FIG. 10 is a diagram illustrating the relationship between the output voltage of the capacitive voltage conversion circuit and the atmospheric pressure in the first embodiment of the present invention. The capacitive voltage conversion circuit 33, corresponding to the vibrators 24, 28 in FIG. Each output voltage-pressure characteristic of 34 (that is, the pressure measuring units 81A and 81B) is illustrated.

  Here, as shown in FIGS. 9 to 10, the output value of each capacitance-voltage conversion circuit is approximately proportional to the amplitude of each corresponding vibrating body. In the characteristic examples shown in FIGS. 9 to 10, the measurement limit is about 1000 Pa on the high pressure side due to the influence of the viscosity of air.

Signals of the calculation results are calculated by combining the output signals V _A and V _B of the two pressure measuring units 81A and 81B (capacitance voltage conversion circuits 33 and 34) having the pressure measurement characteristics illustrated in FIGS. The configuration and operation of the calculation unit 91 that outputs V _PO will be described with reference to the first to third embodiments.

(A) In the first embodiment, a calculation unit 91a composed of an adder is applied as the calculation unit 91 in the circuit configuration of FIG. 5, and the output signal V _A of the capacitance-voltage conversion circuit 33 and the pressure measurement in the pressure measurement unit 81A are applied. In this configuration, a signal V _PO (ad) represented by the following equation (3) obtained by adding the output signal V _B of the capacitive voltage conversion circuit 34 in the unit 81B is output (configuration of the addition method).

[Equation 3]
V _PO (ad) = α _A V _A + α _B V _B (3)
Here, α _A and α _B are coefficients.

(B) FIG. 11 is a diagram showing an example of the relationship between the output value V _PO (ad) of the calculation unit 91a and the atmospheric pressure P in the first embodiment, where the coefficient α _A in the above equation (3) is 1. The case where the coefficient α _B is 2 is illustrated. Note that the vertical axis (output value) in FIG. 11 is linearly displayed.

As shown in FIG. 11, in the wide pressure range from the lower limit side of the measurable pressure range of the pressure measuring unit 81A to the upper limit side of the measurable pressure range of the pressure measuring unit 81B, the output signal V _PO (ad) of the calculating unit 91a And the pressure P have a one-to-one relationship, so that the atmospheric pressure P can be continuously measured over a wide pressure range based on the output signal V _PO (ad) of the calculation unit 91a. .

(A) In the second embodiment, a calculation unit 91m composed of a multiplier is applied as the calculation unit 91 in the circuit configuration of FIG. 5, and the output signal V _A of the capacitance-voltage conversion circuit 33 and the pressure measurement in the pressure measurement unit 81A are applied. In this configuration, a signal V _PO (ml) represented by the following equation (4) obtained by multiplying the output signal V _B of the capacitance-voltage conversion circuit 34 in the unit 81B is output (configuration of multiplication method).

[Equation 4]
V _PO (ml) = βV _A × V _B (4)
Here, β is a coefficient.

(B) FIG. 12 is a diagram showing an example of the relationship between the output value V _PO (ml) of the calculation unit 91m and the atmospheric pressure P in Example 2, and the coefficient β in the above equation (4) is 1. The case is illustrated. In addition, the vertical axis | shaft (output value) of FIG.

As shown in FIG. 12, in the wide pressure range from the lower limit side of the measurable pressure range of the pressure measuring unit 81A to the upper limit side of the measurable pressure range of the pressure measuring unit 81B, the output signal V _PO (ml) of the computing unit 91m And the pressure P have a one-to-one relationship, so that the atmospheric pressure P can be continuously measured over a wide pressure range based on the output signal V _PO (ml) of the calculation unit 91m. .

  Further, in the second embodiment of the multiplication method, since the rate of change of the output signal of the calculation unit is larger than that in the first embodiment of the addition method, the pressure P can be obtained with higher resolution.

(A) In the third embodiment, a calculation unit 91d composed of a divider is applied as the calculation unit 91 in the circuit configuration of FIG. 5, and the output signal V _A of the capacitance-voltage conversion circuit 33 in the pressure measurement unit 81A is subjected to pressure measurement. In this configuration, the signal V _PO (di) expressed by the following equation (5) divided by the output signal V _B of the capacitance-voltage conversion circuit 34 in the unit 81B is output (configuration of the division method).

[Equation 5]
V _PO (di) ＝ γV _A ÷ V _B (5)
Here, γ is a coefficient.
(B) FIG. 13 is a diagram showing an example of the relationship between the output value V _PO (di) of the calculation unit 91d and the atmospheric pressure P in the third embodiment, and the coefficient γ in the above equation (5) is 1. The case is illustrated. The vertical axis (output value) in FIG. 13 is logarithmic.

As shown in FIG. 13, in the wide pressure range from the lower limit side of the measurable pressure range of the pressure measuring unit 81A to the upper limit side of the measurable pressure range of the pressure measuring unit 81B, the output signal V _PO (di) of the calculating unit 91d. And the pressure P have a one-to-one relationship, so that the atmospheric pressure P can be continuously measured over a wide pressure range based on the output signal V _PO (di) of the calculation unit 91d. .

Further, in the third embodiment of the division method, since the rate of change of the output signal of the calculation unit is larger than that in the first embodiment of the addition method, the pressure P can be obtained with higher resolution.
In the above-described first to third embodiments, the output signals V _A and V _{B of the} pressure measuring units 81A and 81B input to the computing unit 91 corresponding to the constant driving voltage method are the capacitance voltage conversion circuits 33 and 34, respectively. It is an Example based on the structure which is each output signal (amplitude of a vibrating body). However, the present invention is not limited to the above configuration, and the configuration in which the output signals V _A and V _B of the pressure measurement units 81A and 81B are combined and calculated by the calculation unit 91 corresponds to the constant amplitude method. The present invention can also be applied to a configuration in which the output signals V _A and V _{B of the} pressure measuring units 81A and 81B input to the calculator 91 are signals based on the voltages of the drive signals.

Moreover, although the example which outputs an analog voltage signal is shown in FIGS. 11-13 as the output signal _VPO of the calculating part 91, you may make it output the digitized signal.
Moreover, although the above-mentioned Examples 1-3 demonstrated the structural example in the vacuum gauge using two pressure measuring parts (vibrating body) from which the pressure range which can be measured differs, this invention is limited to the said structure. Instead, the present invention can also be applied to a vacuum gauge using three or more pressure measuring units (vibrating bodies) having different measurable pressure ranges. For example, the same configuration as in the first to third embodiments can be applied to a vacuum gauge using three pressure measuring units (vibrating bodies) having different measurable pressure ranges to obtain the following configuration. .
(Additional configuration example) All three pressure measuring units (vibrating bodies) are operated simultaneously, and the output signals V _A , V _B , and V _C of the three pressure measuring units are combined and “V _PO (ad) = α _“A V _A + α _B V _B + α _C V _C ” is performed. Here, α _A , α _B , and α _C are coefficients.
(Configuration example of multiplication method) All three pressure measuring units (vibrating bodies) are operated simultaneously, and the output signals V _A , V _B , and V _C of the three pressure measuring units are combined and “V _PO (ml) = βV An operation such as “ _A × V _B × V _C ” is performed. Here, β is a coefficient.
(Configuration example of division method) All three pressure measurement units (vibrating bodies) are operated simultaneously, and the output signals V _A , V _B , and V _C of the three pressure measurement units are combined to obtain “V _PO (di) = γV _A calculation such as “ _A ÷ V _B ÷ V _C ” is performed. Here, γ is a coefficient. In the configuration using three or more pressure measuring units (vibrating bodies) having different measurable pressure ranges, in the case of the division method, V _A and V _{B in} order from the output signal of the pressure measuring unit corresponding to the higher pressure side. , V _C.
(G) Configuration and operation of pressure conversion circuit:
Further, as described above, the pressure conversion unit 92 in the arithmetic processing unit 93 is based on the characteristic data of the relationship between the combination calculation value (calculation signal V _PO ) by the calculation unit 91 and the pressure value, and the combination calculation value at the time of actual measurement. Conversion from (calculation signal V _PO ) to a pressure value is performed. Note that data acquired in advance is used as the characteristic data.

For example, in the case of the second embodiment in which the arithmetic unit 91m composed of a multiplier is applied as the arithmetic unit 91, characteristic data on the relationship between the output value V _PO (ml) of the arithmetic unit 91m and the pressure P as shown in FIG. Get it. The pressure conversion unit 92 is configured to convert a combination calculation value (output value V _PO (ml)) into a pressure value at the time of actual measurement by a conversion unit including a storage unit that stores a data table of the characteristic data. In addition, from the combination calculation value (output value V _PO (ml)) at the time of actual measurement by the conversion means having a storage unit storing the relational expression approximately obtained from the characteristic data curve. It can also be set as the structure which converts into a pressure value. In the arithmetic processing unit 93, the pressure conversion unit 92 configured as described above is provided, and the output signal V _P of the pressure conversion unit 92 is used as the pressure measurement signal of the vacuum gauge, so that each of the pressure measurement units 81A and 81B can be measured Nonlinearity in the vicinity of the overlap pressure region where the ranges overlap can be corrected, and uniform linearity can be provided over the entire region of the pressure measurement range of the vacuum gauge.

As the output signal V _P of the pressure converter 92, the relationship between the pressure value (magnitude of the signal) signal level, for example, the pressure in a uniform proportional coefficient over the entire area of the pressure measurement range of the gauge A signal proportional to the value may be output, or a signal proportional to the logarithm of the pressure value may be output. The output signal V _P of the pressure converter 92 may be, for example, an analog voltage signal, or may be a digitized signal.
FIG. 14 is a plan view showing a different configuration example of the structure constituting the mechanism part of the vacuum gauge according to the first embodiment of the present invention. 15 is a side view of the structure shown in FIG. 14 and 15, the structure constituting the mechanism part of the vacuum gauge includes a vibrating body 4 including a weight 1, a beam 2 and a vibrating body fixing portion 3, and excitation electrodes 5 and 7 for exciting the vibrating body 4. The present invention can also be applied to a vacuum gauge equipped with such a structure, which includes vibration detection electrodes 6 and 8 for detecting the vibration of the vibration body 4.
(L) Different circuit configuration examples of vacuum gauge:
(A) Moreover, the circuit configuration of the vacuum gauge according to the first embodiment of the present invention may be configured as follows. FIG. 16 is a block diagram showing a different circuit configuration example of the vacuum gauge according to the first embodiment of the present invention. In FIG. 16, one vacuum gauge includes a plurality of (for example, two) vibrators having different vibrator thicknesses, beam lengths, vibrator body materials, or areas. Only the circuit configuration of the pressure measuring unit 82A corresponding to the vibrating body is shown, but the circuit configuration of the pressure measuring device 82B corresponding to the other vibrating body is the same.

(B) Circuit configuration:
The circuit configuration example of FIG. 16 corresponds to the structure of the configuration example shown in FIGS. 14 to 15, and the pressure measurement unit 82A corresponding to one vibration body 4 includes the vibration body 4, the excitation electrode 5, 7, vibration detection electrodes 6 and 8, capacitive voltage conversion circuits 53 and 52 that output a voltage corresponding to a change in capacitance between the vibrating body 4 and the vibration detection electrodes 6 and 8, and capacitive voltage conversion circuits 53 and 52 A difference circuit 55 that outputs the difference between the outputs of the difference circuit 55, a phase shift circuit 57 that changes the phase of the output of the difference circuit 55, an amplifier 59 that amplifies the output of the phase shift circuit 57, and the phase of the input signal is inverted 180 degrees. The inverter circuit 61, the initial excitation signal source 63 for initial excitation of the vibrating body 4 in a predetermined vibration direction, and a drive signal switching switch circuit 65 for selecting a signal applied to the excitation electrodes 5 and 7 Has been. Then, the output signal V _B of the output signal V _A and the detailed circuit is not shown pressure measuring portion 82B of the pressure measuring portion 82A combination calculated by the arithmetic unit 91, the combination calculation value (operation signal V _PO) pressure processing unit 93 which outputs as a pressure measurement signal V _P of the gauge is converted into a pressure value is provided by the converter 92.

The configuration of the arithmetic processing unit 93 is the same as the circuit configuration example of FIG.
(C) Operation of the pressure measuring unit:
(C1) Next, the operation of the pressure measurement unit in the circuit configuration example of FIG. 16 will be described. In FIG. 16, when the vibrating body 4 is initially vibrated, the drive signal switching switch circuit 65 is in a state where A and B are connected. A signal having a frequency corresponding to the natural frequency of the vibrating body 4 in a predetermined vibration direction is output from the initial drive signal source 63, the phase thereof is inverted by the inverter circuit 61, the output of the inverter circuit 61 and the initial drive signal source The output of 63 is applied to the excitation electrode 7 and the excitation electrode 5, respectively. The initial excitation signal source 63 is used only during initial driving. After the vibrating body 4 starts to vibrate, the drive signal switching switch circuit 65 is switched, and A and C are connected. Note that the switching control of the drive signal switching switch circuit 65 is performed, for example, by setting the amplitude of the vibrating body 4, that is, the magnitude of the output signal of the difference circuit 55 output according to the displacement of the vibrating body 4 to a preset value. This is performed by detecting the arrival at a switch circuit control unit (not shown) and giving a switching signal from the B side to the C side from the switch circuit control unit to the drive signal switching switch circuit 65 at the detection timing. it can.

  Then, in a state where A and C are connected in the drive signal switching switch circuit 65, the phase of the output signal of the difference circuit 55 is shifted by the phase shift circuit 57, amplified by the amplifier 59, and further the output of the amplifier 59 The phase is inverted by the inversion circuit 61. The output of the inverting circuit 61 and the output of the amplifier 59 are applied to the excitation electrode 7 and the excitation electrode 5, respectively, and the resonance state of the vibrating body 4 in a predetermined vibration direction is maintained.

(C2) When the pressure measurement operation method of the pressure measurement unit 82A is configured to adjust the gain of the amplifier 59 so that the voltage of the drive signal applied to the excitation electrodes 7 and 5 is constant (constant drive voltage method) Corresponding to the Q value in the predetermined vibration direction of the vibrating body 4, the amplitude in the predetermined vibration direction of the vibrating body 4, that is, the magnitude of the signal output from the difference circuit 55 changes according to the displacement amount of the vibrating body To do. Therefore, the output signal V _A of the difference circuit 55 can be used as an output signal as the pressure measuring unit 82A.

Note that if the magnitude of the signal V _A is converted into a Q value in a predetermined vibration direction and further converted into a gas pressure P, pressure measurement in the measurable pressure range of the pressure measuring unit 82A can be performed. . Further, the conversion from the output signal (amplitude of the vibrating body) of the difference circuit 55 to the pressure value can be directly performed without using the Q value.

    (C3) Further, the pressure measuring operation method of the pressure measuring unit 82A is set to the amplitude in the predetermined vibration direction of the vibrating body 4, that is, the magnitude of the output signal of the difference circuit 55 output according to the displacement of the vibrating body 4 ( A configuration in which the gain of the amplifier 59 is adjusted so that the amplitude of the vibrating body is constant (constant amplitude method) may be employed. In this case, since the voltage of the drive signal applied from the amplifier 59 to the excitation electrodes 7 and 5 changes corresponding to the Q value in the predetermined vibration direction of the vibrating body 4, the voltage of this drive signal is changed to the pressure measuring unit 82A. As an output signal.

  If the voltage of the drive signal is converted into a Q value in a predetermined vibration direction and further converted into a gas pressure P, pressure measurement within the measurable pressure range of the pressure measuring unit 82A can be performed. Further, the conversion from the voltage of the drive signal to the pressure P value can be directly performed without using the Q value.

    (C4) As described above, in the circuit configuration example of FIG. 16, a single vacuum gauge includes a plurality of vibrators having at least one of the thickness of the vibrator, the length of the beam, the material of the vibrator, or the area. Each pressure measurement system corresponding to each vibrating body includes a vibrating body, a vibrating electrode unit including a pair of vibrating electrodes installed along the vibration direction on both sides of the vibrating body, and vibrations of the vibrating body. A phase shift circuit for changing a phase of a detection signal of the vibration detection unit, an amplifier for amplifying the output signal of the phase shift circuit, and an inversion for inverting the phase of the output signal of the amplifier A drive signal generation unit comprising a circuit, and applying each output signal of the inverting circuit and the amplifier to a set of excitation electrodes as a reverse-phase drive signal based on the detection signal of the vibration detection unit. Resonance is maintained It is configured.

(D) Configuration and operation of the calculation unit:
Next, in the circuit configuration example of FIG. 16, the configuration and operation of the calculation unit 91 that calculates the output signals V _A and V _B of the two pressure measurement units 82A and 82B in combination and outputs the calculation result as the signal V _PO. These are the same as the configuration and operation described in the first to third embodiments using the circuit configuration example of FIG.

(E) Configuration and operation of the pressure converter:
Further, the configuration and operation of the pressure conversion unit 92 in the circuit configuration of FIG. 16 are the same as those described in the circuit configuration example of FIG.

(F) Also, in the circuit configuration example of FIG. 16, as in the circuit configuration example of FIG. 5 described above, two different at least one of the thickness of the vibrating body, the length of the beam, the material or the area of the vibrating body is different. Although an example in the case of using a vibrating body has been shown, it is even wider by using three or more vibrating bodies that differ in at least one of the thickness of the vibrating body, the length of the beam, the material of the vibrating body, or the area. It becomes possible to measure the gas pressure in the region.
(Nu) Further different circuit configuration examples of vacuum gauge:
(A) Further, the circuit configuration of the vacuum gauge according to the first embodiment of the present invention can be further configured as follows. FIG. 17 is a block diagram showing still another circuit configuration example of the vacuum gauge according to the first embodiment of the present invention. FIG. 17 shows one vibrating body in a configuration in which at least one of the vibrating body thickness, beam length, vibrating body material or area is different (for example, two) in one vacuum gauge. Only the circuit configuration of the pressure measuring unit 83A corresponding to the above is shown, but the circuit configuration of the pressure measuring device 83B corresponding to other vibrating bodies is the same.

(B) Circuit configuration:
The circuit configuration example of FIG. 17 corresponds to the structure of the configuration example shown in FIGS. 14 to 15 similarly to the circuit configuration example of FIG. 16. Compared with the circuit configuration example of FIG. Although the configuration of the parts is different, the configuration is the same as that of FIG. 16 in other points.

In FIG. 17, the pressure measuring unit 83A corresponding to one vibrating body includes a vibrating body 4, excitation electrodes 5 and 7, vibration detection electrodes 6 and 8, and a static between the vibrating body 4 and the vibration detection electrodes 6 and 8. Capacitance / voltage conversion circuits 53 and 52 that output a voltage corresponding to a change in capacitance, a difference circuit 55 that outputs a difference between outputs of the capacitance / voltage conversion circuits 53 and 52, a drive signal source 73, and a drive signal source 73 It comprises an amplifier 59 for amplifying the output and an inverting circuit 61 for inverting the phase of the input signal by 180 degrees. Then, the output signal V _A of the pressure measuring unit 83A and the output signal V _B of the pressure measuring unit 83B whose detailed circuit is not shown are calculated by the calculation unit 91 and the combination calculation value (calculation signal V _PO ) is calculated as the pressure. processing unit 93 which outputs as a pressure measurement signal V _P of the gauge is converted into a pressure value is provided by the converter 92.

  The circuit configuration example of FIG. 17 does not include the phase shift circuit 57, the initial excitation signal source 63, and the drive signal switching switch circuit 65 as in the circuit configuration example of FIG. A driving signal source 73 used not only for initial driving but also for driving in a steady pressure measurement state is provided.

The configuration of the arithmetic processing unit 93 is the same as the circuit configuration example of FIG.
(C) Operation of the pressure measuring unit:
(C1) Next, the operation of the pressure measurement unit in the circuit configuration example of FIG. 17 will be described. In FIG. 17, the signal output from the drive signal source 73 is amplified by the amplifier 59, and the phase of the output of the amplifier 73 is inverted by the inverting circuit 61. By applying the output of the inverting circuit 61 and the output of the amplifier 59 to the excitation electrodes 5 and 7, respectively, the vibrating body 4 is vibrated in a predetermined vibration direction. Since the capacitance between the vibrating body 4 and the vibration detection electrodes 6 and 8 changes when the vibrating body 4 vibrates in a predetermined vibration direction, the capacitance-voltage conversion circuits 53 and 52 The voltage is converted into a voltage corresponding to the change in capacitance, that is, the amplitude of the vibrating body 4 in a predetermined vibration direction. Since the output voltages of the capacitor voltage conversion circuits 52 and 53 are in opposite phases, the difference between the output voltages is obtained by the difference circuit 55 to obtain a final output voltage corresponding to the amplitude in a predetermined vibration direction of the vibrating body 4.

(C2) When the pressure measurement operation method of the pressure measurement unit 83A is configured to adjust the gain of the amplifier 59 so that the voltage of the drive signal applied to the excitation electrodes 5 and 7 is constant (drive voltage constant method) Corresponding to the Q value in the predetermined vibration direction of the vibration body 4, the amplitude in the predetermined vibration direction of the vibration body 4, that is, the magnitude of the signal output from the difference circuit 55 according to the displacement amount of the vibration body 4 is Change. Therefore, the output signal V _A of the difference circuit 55 can be used as an output signal as the pressure measuring unit 83A.

Note that if the magnitude of the signal V _A is converted into a Q value in a predetermined vibration direction and further converted into a gas pressure P, pressure measurement in the measurable pressure range of the pressure measuring unit 83A can be performed. . Further, the conversion from the output signal (amplitude of the vibrating body) of the difference circuit 55 to the pressure value can be directly performed without using the Q value.

    (C3) Further, the pressure measuring operation method of the pressure measuring unit 83A is set to the amplitude of the vibrating body 4 in a predetermined vibration direction, that is, the magnitude of the output signal of the difference circuit 55 output according to the displacement of the vibrating body 4 ( A configuration in which the gain of the amplifier 59 is adjusted so that the amplitude of the vibrating body is constant (constant amplitude method) may be employed. In this case, since the voltage of the drive signal applied from the amplifier 59 to the excitation electrodes 5 and 7 changes corresponding to the Q value in the predetermined vibration direction of the vibrating body 4, the voltage of this drive signal is changed to the pressure measuring unit 83A. As an output signal.

  If the voltage of the drive signal is converted into a Q value in a predetermined vibration direction and further converted into a gas pressure P, pressure measurement in the measurable pressure range of the pressure measurement unit 83A can be performed. Further, the conversion from the voltage of the drive signal to the pressure value can be directly performed without using the Q value.

(D) Configuration and operation of the calculation unit:
Next, in the circuit configuration example of FIG. 17, the configuration and operation of the calculation unit 91 that calculates by combining the output signals V _A and V _B of the two pressure measurement units 83A and 83B and outputs the calculation result as the signal V _PO. These are the same as the configuration and operation described in the first to third embodiments using the circuit configuration example of FIG.

(E) Configuration and operation of the pressure converter:
The configuration and operation of the pressure conversion unit 92 in the circuit configuration of FIG. 17 are the same as those described in the circuit configuration example of FIG.

(F) Also, in the circuit configuration example of FIG. 17, as in the above-described circuit configuration example of FIG. 5, there are two different at least one of the thickness of the vibrating body, the length of the beam, the material or the area of the vibrating body. Although an example in the case of using a vibrating body has been shown, it is even wider by using three or more vibrating bodies that differ in at least one of the thickness of the vibrating body, the length of the beam, the material of the vibrating body, or the area. It becomes possible to measure the gas pressure in the region.
(Further different examples of design values for vibrators)
Next, the relationship between the gas pressure P and the Q value of the vibrating body will be described based on still different examples of the design values of the vibrating body according to the first embodiment of the present invention. FIG. 18 is a diagram illustrating still another example of the design values of the vibrating body according to the first embodiment of the present invention. Specific examples 1 to 5 are shown as design values of two vibrating bodies having different measurable pressure ranges. ing.
[Specific Example 1]
Design (I) and design (II) in FIG. 18 are examples of design values of the vibrating body 4 in the specific example 1. In the design (I) and the design (II), the thickness of the vibrating body (= beam thickness) ( C value) is different. FIG. 19 shows the relationship between the gas pressure P and the Q value of the vibrator in the first specific example of the design values of the vibrator shown in FIG. However, this is a case where the Q value peculiar to the vibrator is 100000, the temperature T is 300K, and the gas to be evaluated is air, and the same applies to the following specific examples. From FIG. 19, it can be seen that by using two vibrating bodies having different thicknesses, it is possible to widen the pressure range that can be measured by about one digit compared to the case of one vibrating body. .
[Specific Example 2]
Design (III) and design (IV) in FIG. 18 are examples of design values of the vibrating body 4 in the specific example 2. In the design (III) and the design (IV), the beam length (D value) of the vibrating body is shown. Is different. FIG. 20 shows the relationship between the pressure P of the gas and the Q value of the vibrator in the specific example 2 of the design value of the vibrator. From FIG. 20, it can be seen that by using two vibrating bodies having different beam lengths, it is possible to widen the pressure range that can be measured by about 0.5 digits as compared to the case of one vibrating body.
[Specific Example 3]
Design (V) and design (VI) in FIG. 18 are examples of design values of the vibrating body 4 in the specific example 3, and the material (Young's modulus) of the vibrating body is different between the design (V) and the design (VI) ( Silicon: 130Gpa, Aluminum: 70GPa). FIG. 21 shows the relationship between the gas pressure P and the vibration member Q value in specific example 3 of the design values of the vibration member. From FIG. 21, it can be seen that by using two vibrators having different vibrator materials, it is possible to slightly widen the measurable pressure range as compared with the case of one vibrator.
[Specific Example 4]
Design (VII) and design (VIII) in FIG. 18 are examples of design values of the vibrating body 4 in the specific example 4. In the designs (VII) and (VIII), the area of the weight of the vibrating body (A × B value) ) Is different. FIG. 22 shows the relationship between the gas pressure P and the Q value of the vibrating body in specific example 4 of the design value of the vibrating body. It can be seen from FIG. 22 that by using two vibrating bodies having different weight areas, it is possible to widen the pressure range that can be measured by an order of magnitude less than that of a single vibrating body.
[Specific Example 5]
From the above equation (1), the coefficient part a of 1 / P is expressed as the following equation (6).

  It can be seen from this equation (6) that the measurement range that can be measured can be greatly changed by using two vibrators having greatly different coefficients, that is, a large difference. .

  Design (IX) and design (X) in FIG. 18 are examples of design values of the vibrating body 4 in the specific example 5. In the design (IX) and the design (X), the length of the beam of the vibrating body (D value). , Area (A × B value) and beam thickness (C value) are different. FIG. 23 shows a relationship between the gas pressure P and the Q value of the vibrating body in the specific example 5 of the design value of the vibrating body. From FIG. 23, it is possible to widen the pressure range that can be measured by about three orders of magnitude compared to the case of one vibrator by using two vibrators having the coefficients of Equation (6) that are greatly different from each other. I know that there is.

  And according to 1st Embodiment of this invention, the output signals from the two pressure measurement parts corresponding to the two vibrating bodies designed with the design values shown in the above specific examples 1 to 5, for example, are combined. By adopting a configuration with a calculation unit for calculation, it is possible to measure a wide range of gas pressures without making measurement discontinuous with a single vacuum gauge, and to realize a vacuum gauge with a simplified circuit configuration. be able to.

In addition, although the case where two vibrating bodies are used has been described for all of the specific examples described above, it is also possible to use three or more vibrating bodies in the first embodiment of the present invention.
(L) According to the first embodiment of the present invention as described above, a plurality of vibrating bodies having different measurable pressure ranges and partially overlapping are constantly vibrated, and each pressure measurement corresponding to each vibrating body is performed. The output signals of the units are combined and calculated by the calculation unit, and the output signal of the arithmetic processing unit based on this combination calculation value is used as the pressure measurement signal of the vacuum gauge, so that the measurement is discontinuous with one vacuum gauge Thus, it is possible to realize a vacuum gauge that can measure the pressure of a wide range of gas and that has a simplified circuit configuration.
[Second Embodiment]
The vacuum gauge according to the second embodiment of the present invention causes the vibrating body to vibrate simultaneously in two vibration directions having different measurable pressure ranges and partially overlapping, and each pressure measuring unit corresponding to each vibration direction. The basic configuration is such that the output signals are combined and calculated by the calculation unit, and the output signal of the arithmetic processing unit based on the combination calculation value is used as the pressure measurement signal of the vacuum gauge.
(B) Structure of the structure that forms the mechanism of the vacuum gauge:
FIG. 24 is a plan view of a structure that forms a mechanism part of a vacuum gauge according to the second embodiment of the present invention, and FIG. 25 is a side view of the structure shown in FIG. 24 and 25, the structure constituting the mechanism part of the vacuum gauge includes a vibrating body 104 including a weight 101, a beam 102 and a vibrating body fixing portion 103, and an excitation electrode for exciting the vibrating body 104 in the first vibration direction. 105 and 106, excitation electrodes 107 and 108 for exciting the vibration body 104 in the second vibration direction, vibration detection electrodes 109 and 110 for detecting vibration in the first vibration direction of the vibration body 104, and the vibration body 104 Vibration detection electrodes 111 and 112 for detecting vibrations in the second vibration direction.
(B) Relationship between the shape of the vibrating body, the Q value of the vibrating body and the gas pressure P:
Next, the relationship between the shape of the vibrating body 104, the Q value of the vibrating body 104, and the gas pressure P is the same as that described for the vibrating body 4 in the item (b) of the first embodiment described above. the relationship between the Q value and the gas pressure P of the body 104, the natural frequency, the area weight of the mass m, the S undergoes the resistance of the gas of the vibrating body 104 f _r, the gas and R constant, temperature T , M is the mass per 1 mol of gas molecules, the Q value of the vibrating body 104 can be expressed as in the above equation (2).
(C) Examples of design values of the vibrator:
FIG. 26 is a diagram illustrating an example of the design value of the vibrating body according to the second embodiment of the present invention, and FIG. 27 is a diagram illustrating the gas pressure P and the Q of the vibrating body at the design value of the vibrating body illustrated in FIG. It is a figure which shows the relationship with a value. As shown in FIG. 27, the gas pressure that can be measured when vibrating in the first vibration direction is about 10 Pa to about 10000 Pa, and the gas that can be measured when vibrating in the second vibration direction. The pressure is about 0.1 Pa to about 100 Pa. That is, the gas pressure that can be measured according to the vibration direction can be changed. Note that the natural frequencies in the first and second vibration directions of the vibrating body shown in FIG. 26 are approximately 1680 Hz and approximately 560 Hz, respectively, when the vibrating body is made of silicon, for example.
(D) Circuit configuration of vacuum gauge:
Next, a circuit configuration of the vacuum gauge according to the second embodiment of the present invention will be described. FIG. 28 is a block diagram showing a circuit configuration example of a vacuum gauge according to the second embodiment of the present invention, in which voltages according to changes in electrostatic capacitances of the vibrating body 104 and the vibration detection electrodes 109, 110, 111, and 112 are shown. Capacitor voltage conversion circuits 120, 121, 122, and 123, a difference circuit 124 that outputs a difference in output between the capacitor voltage conversion circuits 120 and 121, and a difference that outputs a difference in output between the capacitor voltage conversion circuits 122 and 123. The circuit 125, the phase shift circuit 126 that changes the phase of the output of the difference circuit 124, the amplifier 128 that amplifies the output of the phase shift circuit 126, the inversion circuit 130 that inverts the phase of the input signal by 180 degrees, and the vibrating body 104 1. Initial excitation signal source 132 for initial excitation in the vibration direction of 1, a switch circuit 134 for selecting a signal applied to the excitation electrodes 105 and 106, and a phase shift circuit for changing the phase of the output of the difference circuit 125 127, an amplifier 129 for amplifying the output of the phase shift circuit 127, An inversion circuit 131 for inverting the phase of the input signal by 180 degrees, an initial excitation signal source 133 for initial excitation of the vibrating body 104 in the second vibration direction, and signals applied to the excitation electrodes 107 and 108 Each of the output signals V _A and V _B of the switch circuit 135 and the difference circuits 124 and 125 that are selected by the calculation unit 191 is combined and calculated, and the combination calculation value (calculation signal V _PO ) is converted into a pressure value by the pressure conversion unit 192. an arithmetic processing unit 193 to output as a pressure measurement signal V _P of the gauge conversion to.

As shown in FIG. 28, the vibrating body 104, the excitation electrodes 105 and 106, the vibration detection electrodes 109 and 110, the capacity voltage conversion circuits 120 and 121, the difference circuit 124, the phase shift circuit 126, the amplifier 128, and the inverting circuit 130, the initial excitation signal source 132, and the switch circuit 134 constitute a pressure measurement unit 181A, and the output signal V _A of the difference circuit 124 is an output signal as the pressure measurement unit 181A. Further, the vibrating body 104, the excitation electrodes 107 and 108, the vibration detection electrodes 111 and 112, the capacitance voltage conversion circuits 122 and 123, the difference circuit 125, the phase shift circuit 127, the amplifier 129, the inverting circuit 131, and the initial excitation signal source 133, pressure measuring portion 181B by the switch circuit 135 is configured, the output signal V _B of the difference circuit 125 is an output signal of the pressure measuring unit 181B.

  In addition, the combination calculation by the calculation unit 191 of the calculation processing unit 193 is performed in the state where the pressure measurement range of the vacuum gauge is obtained while the vibrating body 104 is simultaneously vibrated in two vibration directions and the pressure measurement units 181A and 181B are operated. This is performed in all areas. As the arithmetic unit 191, as in the first embodiment, an arithmetic unit 191a composed of an adder, an arithmetic unit 191m composed of a multiplier, an arithmetic unit 191d composed of a divider, and the like can be applied.

In addition, the pressure conversion unit 192 in the arithmetic processing unit 193 determines the combination calculation value (calculation signal V _PO in actual measurement) based on the characteristic data of the relationship between the combination calculation value (calculation signal V _PO ) and the pressure value by the calculation unit 191. ) To a pressure value.

In FIG. 28, the arithmetic processing unit 193 includes a pressure conversion unit 192 on the output side of the calculation unit 191, and a signal based on the pressure value obtained by the pressure conversion unit 192 is output as a pressure measurement signal V _P of the vacuum gauge. However, the present invention is not limited to the above configuration. That is, in the present invention, basically, a wide pressure range from the lower limit side of the measurable pressure range of the low pressure region pressure measurement unit to the upper limit side of the measurable pressure range of the high pressure region pressure measurement unit (pressure measurement of the vacuum gauge). In the entire range), a measurement signal that changes continuously according to the pressure and has a one-to-one relationship with the pressure is obtained, and based on this measurement signal, the atmospheric pressure can be set within a wide pressure range (vacuum pressure range). It suffices if measurement can be continuously performed over the entire measurement range. Therefore, in the present invention, depending on such signal form required as a pressure measurement signal of the gauge, for example, without providing the pressure converter unit 192 in the arithmetic processing unit 193, the gauge of the operation signal V _PO from the arithmetic unit 191 It can also be configured to output as a pressure measurement signal.
(E) Operation of pressure measurement unit in vacuum gauge:
(A) Next, the operation of the pressure measurement unit in the vacuum gauge according to the second embodiment of the present invention using the vibrating body shown in FIG. 26 will be described. In FIG. 28, when the vibrating body 104 is initially vibrated, the switch circuits 134 and 135 are in a state where A and B and D and E are connected, respectively. A signal having a frequency corresponding to the natural frequency of the vibrating body 104 in the first vibration direction is output from the initial drive signal source 132 and applied to the excitation electrode 105 through the inversion circuit 130 and also to the excitation electrode 106. Applied. On the other hand, a signal having a frequency corresponding to the natural frequency of the vibrating body 104 in the second vibration direction is output from the initial drive signal source 133 and applied to the excitation electrode 107 via the inversion circuit 131 and the excitation electrode 108. Is also applied. The initial excitation signal sources 132 and 133 are used only during initial driving, and after the vibrating body 104 starts to vibrate, the switch circuits 134 and 135 are switched, and A and C, and D and F are connected, respectively. It becomes. Note that the switching control of the switch circuits 134 and 135 is, for example, a value in which the amplitude of the vibrating body 104, that is, the magnitudes of the output signals of the difference circuits 124 and 125 output according to the displacement of the vibrating body 104 are set in advance. Is detected by a switch circuit control unit (not shown), and at the detection timing, a switch signal from the B side to the C side and a switch signal from the E side to the F side from the switch circuit control unit to the switch circuits 134 and 135 are detected. This can be done by giving each switching signal.

  In the state where A and C are connected and D and F are connected in the switch circuits 134 and 135, the phase of the output signal of the difference circuit 124 is shifted by the phase shift circuit 126 and amplified by the amplifier 128. Further, the phase of the output of the amplifier 128 is inverted by the inversion circuit 130. The output of the inverting circuit 130 and the output of the amplifier 128 are applied to the excitation electrode 105 and the excitation electrode 106, respectively, and the resonance state of the vibrating body 104 in the first vibration direction is maintained. On the other hand, the phase of the output signal of the difference circuit 125 is shifted by the phase shift circuit 127, amplified by the amplifier 129, and further the phase of the output of the amplifier 129 is inverted by the inversion circuit 131. The output of the inverting circuit 131 and the output of the amplifier 129 are applied to the excitation electrode 107 and the excitation electrode 108, respectively, and the resonance state of the vibrating body 104 in the second vibration direction is maintained.

(B) The pressure measuring operation method of each pressure measuring unit 181A, 181B is set so that the voltage of the drive signal applied to the excitation electrodes 105 and 106 is constant, and the gain of the amplifier 128 is applied to the excitation electrodes 107 and 108. When the gain of the amplifier 129 is adjusted so that the voltage of the drive signal to be applied is constant (a constant drive voltage method), it corresponds to each Q value in the first and second vibration directions of the vibrating body 104. Thus, the magnitudes of the signals output from the difference circuits 124 and 125 change in accordance with the respective amplitudes of the vibrating body 104 in the first and second vibration directions, that is, the displacement amount of the vibrating body. Therefore, the signals V _A and V _B output from the difference circuits 124 and 125 can be used as output signals as the pressure measuring units 181A and 181B.

  If the magnitudes of the output signals of the difference circuits 124 and 125 are converted into Q values in the first and second vibration directions and further converted into gas pressures P, the pressure measurement units 181A and 181B Each pressure measurement in the measurable pressure range can be performed. Moreover, the conversion from each output signal (amplitude of the vibrating body) of the difference circuits 124 and 125 to each pressure value can be directly performed without passing through the Q value.

Here, in the case of the vibrator having the design values shown in FIG. 26 and made of silicon, the voltage of the drive signal applied to the excitation electrodes 105 and 106 is constant in the first vibration direction, for example. When the gain of the amplifier 128 is adjusted, the relationship between the magnitude of the output signal of the difference circuit 124 (the amplitude of the vibrating body) and the pressure P value is as shown in FIG. 29 (about 10 Pa or more). In the high pressure region, the amplitude is almost inversely proportional to the pressure, and on the low pressure side, the amplitude is saturated toward its maximum limit value. Here, the description of the scale values of “1.00E-07” to “1.00E-04” in the vertical axis “amplitude (m)” in FIG. 29 is “1.00 × 10 ⁻⁷ ” to “ 1.00 × 10 ⁻⁴ ”.

  As described above, in the present invention, the output signals of the pressure measurement units 181A and 181B are combined and calculated by the calculation unit 191, and the output signal of the calculation processing unit 193 based on the combination calculation value is used as the pressure measurement signal of the vacuum gauge. However, when each pressure measurement signal based on the output signal of each difference circuit in the above-mentioned constant drive voltage method is also output as a vacuum gauge, conversion from the output signal of each difference circuit to each pressure value For example, it can be performed as follows. That is, characteristic data on the relationship between the magnitudes of the output signals of the difference circuits 124 and 125 (the amplitude of the vibrating body) and the pressure values is acquired in advance. The conversion means having a storage unit storing the data table of the characteristic data may be configured to convert each output signal (amplitude of the vibrating body) into each pressure value at the time of actual measurement. A configuration for converting each output signal (amplitude of the vibrating body) into each pressure value at the time of actual measurement by a conversion means having a storage unit storing a relational expression approximately obtained from the curve of the characteristic data. It can also be.

  (C) Further, the pressure measurement operation method of each pressure measuring unit 181A, 181B is determined according to the amplitude of the vibrating body 104, that is, the magnitude of each output signal of the difference circuits 124, 125 output according to the displacement of the vibrating body 104. The gains of the amplifiers 128 and 129 can be adjusted so as to be constant (constant amplitude method). In this case, the voltages of the drive signals applied from the amplifiers 128 and 129 to the excitation electrodes 105, 106, 107, and 108 are changed corresponding to the respective Q values in the first and second vibration directions of the vibrating body 104. Therefore, the voltage of each drive signal can be used as each output signal as the pressure measuring units 181A and 181B.

  If the voltage of each driving signal is converted into each Q value in the first and second vibration directions, and further converted into the gas pressure P, the pressure measurement units 181A and 181B can measure each pressure range. Each pressure measurement can be made. Further, the conversion from the voltage of each drive signal to each pressure value can be directly performed without passing through the Q value.

Here, in the case of the vibrator having the design values shown in FIG. 26 and the material being silicon, for example, in the first vibration direction, the magnitude of the output signal of the difference circuit 124 (the amplitude of the vibrator) is constant. The relationship between the magnitude of the driving signal (driving voltage) and the pressure value when adjusting the gain of the amplifier 128 is as follows. In the high voltage region (about 10 Pa or more) as shown in FIG. Is substantially proportional to the pressure, and on the low pressure side, the drive voltage decreases so as to saturate toward the minimum limit value. Here, the description of the scale values of “1.00E-01” to “1.00E + 02” in the vertical axis “drive voltage (Vpeak)” in FIG. 30 is “1.00 × 10 ⁻¹ ” to “1”, respectively. .00 × 10 ⁺² ”.

  As described above, in the present invention, the output signals of the pressure measurement units 181A and 181B are combined and calculated by the calculation unit 191, and the output signal of the calculation processing unit 193 based on the combination calculation value is used as the pressure measurement signal of the vacuum gauge. However, when each pressure measurement signal based on each drive signal in the constant amplitude method is also output as a vacuum gauge, conversion from each drive signal to each pressure value is performed as follows, for example. Can be done. That is, for example, the characteristic data of the relationship between the voltage (the magnitude) of each drive signal and each pressure value is acquired. The conversion means having a storage unit storing a data table of the characteristic data can be configured to convert the voltage of each drive signal into each pressure value at the time of actual measurement. It is also possible to adopt a configuration for converting the voltage of each drive signal into each pressure value at the time of actual measurement by a conversion means having a storage unit that stores a relational expression approximately obtained from a curve.

(D) Here, in the circuit configuration example of FIG. 28, the output signals V _A and V _{B of the} pressure measuring units 181A and 181B input to the calculator 191 correspond to the above-described constant driving voltage method. , 125 output signals (vibration body amplitude) are shown, but the present invention is not limited to the above configuration, and is input to the arithmetic unit 191 corresponding to the constant amplitude method. The output signals V _A and V _{B of the} pressure measuring units 181A and 181B can be configured to be signals based on the voltage of each drive signal.

(E) In the second embodiment of the present invention, the vibrating body 104 is vibrated simultaneously in the first vibration direction and the second vibration direction, which are different in measurable pressure range and partially overlap, Since the gas pressure is simultaneously measured in the vibration direction, it is possible to continuously measure the gas pressure, unlike when the vibration direction is switched depending on the gas pressure. Further, since it is not necessary to switch the vibration direction depending on the gas pressure, the control circuit and the like are simplified.
(F) Configuration and operation of the calculation unit in the vacuum gauge:
Next, in the circuit configuration example of FIG. 28 in the second embodiment of the present invention, the output signals V _A and V _B of the two pressure measuring units 181A and 181B are calculated in combination, and the calculation result is output as the signal V _PO. The configuration and operation of the calculation unit 191 are the same as the configuration and operation of the calculation unit 91 described in the first to third embodiments using the circuit configuration example of FIG.
(G) Configuration and operation of pressure converter:
The configuration and operation of the pressure conversion unit 192 in the circuit configuration of FIG. 28 are the same as those described for the pressure conversion unit 92 in the circuit configuration example of FIG.
(H) According to the second embodiment of the present invention as described above, the vibrating body is simultaneously vibrated in two vibration directions having different measurable pressure ranges and partially overlapping, and corresponding to each vibration direction. By combining the output signals of each pressure measurement unit with the calculation unit and using the output signal of the arithmetic processing unit based on this combination calculation value as the pressure measurement signal of the vacuum gauge, measurement can be performed with one vacuum gauge. Without being discontinuous, it is possible to measure a wide range of gas pressures and realize a vacuum gauge with a simplified circuit configuration.

1, 21, 25, 101 ... weight
2, 22, 26, 102 ... beam
3, 23, 27, 103 ... vibrating body fixing part
4, 24, 28, 104 ... Vibrating body
5, 7, 29, 30, 105 to 108 ... excitation electrodes
6, 8, 31, 32, 109 to 112 ... Vibration detection electrode
33, 34, 52, 53, 120-123 ... capacity voltage conversion circuit
35, 36, 57, 126, 127 ... Phase shift circuit
37,38,59,128,129 ... Amplifier
39, 40, 65, 134, 135 ... Switch circuit for driving signal switching
41, 42, 63, 132, 133 ... Signal source for initial drive
55, 124, 125 ... Difference circuit
61, 130, 131 ... Inversion circuit
73 ... Drive signal source
81A, 81B, 82A, 82B, 83A, 83B, 181A, 181B ... Pressure measurement unit
91,191 ... Calculation unit
92,192 ... Pressure converter
93, 193 ... arithmetic processing unit

Claims (14)

In a vacuum gauge that provides a plurality of pressure measuring units that measure the pressure of the atmosphere from the vibration characteristics of the vibrating body held in a resonance state, and measures the pressure of a common atmosphere by each of the pressure measuring units,
The pressure ranges that can be measured by each pressure measuring unit are made different, and the pressure ranges are partially overlapped,
In the entire region of the pressure measurement range of the gauge, adds the output signal of the pressure measuring unit for the same atmosphere, a vacuum gauge, characterized in that a calculation unit for calculating a pressure measurement signal by multiplying or division operations . The vacuum gauge according to claim 1,
A pressure conversion unit that converts a pressure measurement signal calculated by the calculation unit into a pressure value based on characteristic data of a relationship between a calculation value and a pressure value by the calculation unit and outputs the pressure value as a pressure value. Vacuum gauge. The vacuum gauge according to claim 2 ,
The said pressure conversion part performs the conversion from the calculated value at the time of an actual measurement to a pressure value by the conversion means provided with the memory | storage part which stored the data table of the said characteristic data, The vacuum gauge characterized by the above-mentioned. The vacuum gauge according to claim 2 ,
The pressure conversion unit performs conversion from a calculated value to a pressure value at the time of actual measurement by a conversion unit including a storage unit that stores a relational expression approximately obtained from the curve of the characteristic data. Vacuum gauge. The vacuum gauge according to any one of claims 1 to 4 ,
A vibration body, a vibration electrode unit that drives the vibration body by electrostatic force, and a drive signal generation unit that generates a drive signal to vibrate the vibration body, and the drive signal is supplied to the vibration electrode unit. A vacuum gauge provided with a pressure measuring unit that applies pressure to hold the vibrating body in a resonance state and measures the pressure of the atmosphere from the vibration characteristics of the vibrating body,
A plurality of the vibrators are provided in a common atmosphere in the vacuum gauge, each of the pressure ranges that can be measured by the vibrators is different, and the pressure ranges are partially overlapped.
A plurality of the pressure measuring units are provided corresponding to the vibrating bodies,
A vacuum gauge comprising a calculation unit that calculates a pressure measurement signal by adding, multiplying, or dividing an output signal of each pressure measurement unit for the same atmosphere in all the pressure measurement ranges of the vacuum gauge. The vacuum gauge according to claim 5 ,
Each of the vibrators has a different pressure range that can be measured when at least one of thickness, beam length, material, or area is different . The vacuum gauge according to claim 5 or 6,
The pressure measurement unit includes a vibration detection unit that detects vibration of the vibrating body,
The drive signal generation unit generates a drive signal for exciting the vibrating body by changing the phase of the detection signal and amplifying the detection signal based on the detection signal of the vibration detection unit. Total. The vacuum gauge according to claim 7 ,
The pressure measurement unit includes a vibration electrode unit including a pair of vibration electrodes disposed along the vibration direction on both sides of the vibration body, and a phase shift circuit that changes a phase of a detection signal of the vibration detection unit; A drive signal generation unit comprising an amplifier that amplifies the output signal of the phase shift circuit and an inversion circuit that inverts the phase of the output signal of the amplifier, as a drive signal having a reverse phase based on the detection signal of the vibration detection unit A vacuum gauge that maintains a resonance state of a vibrating body by applying output signals of the inverting circuit and the amplifier to the set of excitation electrodes, respectively . The vacuum gauge according to any one of claims 1 to 4 ,
A vibrator configured to vibrate in a first vibration direction and a second vibration direction orthogonal to the first vibration direction, and an excitation electrode unit that drives the vibration body by electrostatic force; A vibration detection unit that detects the vibration of the vibration body, and a drive signal that generates a drive signal for exciting the vibration body by changing the phase of the detection signal and amplifying the detection signal based on the detection signal of the vibration detection unit A vacuum gauge that measures the pressure of the atmosphere from the vibration characteristics of the vibrating body by holding the vibrating body in a resonance state by applying the drive signal to the excitation electrode unit,
As the excitation electrode unit, provided with first and second excitation electrode units for causing the vibrating body to vibrate in first and second vibration directions, respectively.
The vibration detection unit includes first and second vibration detection units that detect vibrations in the first and second vibration directions of the vibrating body, respectively.
A first pressure measurement unit that measures a pressure by vibrating the vibrating body in a first vibration direction by applying a drive signal based on a detection signal of the first vibration detection unit to the first excitation electrode unit. When,
A second pressure measurement unit that measures a pressure by vibrating the vibrating body in a second vibration direction by applying a drive signal based on the detection signal of the second vibration detection unit to the second excitation electrode unit. And
The first and second pressure measuring units simultaneously vibrate the vibrating body in the first and second vibration directions to simultaneously measure each pressure in each vibration direction;
The pressure ranges that can be measured by the first and second pressure measuring units are different, and the pressure ranges are partially overlapped,
A calculation unit is provided for calculating the pressure measurement signal by adding, multiplying, or dividing the output signals of the first and second pressure measurement units for the same atmosphere in the entire pressure measurement range of the vacuum gauge. A characteristic vacuum gauge. The vacuum gauge according to claim 9 ,
The first excitation electrode unit includes a pair of excitation electrodes including first and second excitation electrodes disposed along the first vibration direction on both sides of the vibrating body. As two excitation electrode portions, a set of excitation electrodes composed of third and fourth excitation electrodes installed along the second vibration direction on both sides of the vibrating body,
The drive signal generation unit includes first and second phase shift circuits that change phases of detection signals of the first and second vibration detection units, and each of the first and second phase shift circuits. First and second amplifiers for respectively amplifying output signals; and first and second inversion circuits for inverting the phases of the output signals of the first and second amplifiers, respectively.
Applying output signals of the first inversion circuit and the first amplifier to the first and second excitation electrodes, respectively, as drive signals having opposite phases based on the detection signal of the first vibration detection unit And maintaining the resonance state in the first vibration direction of the vibrator,
Applying the output signals of the second inversion circuit and the second amplifier to the third and fourth excitation electrodes, respectively, as drive signals having opposite phases based on the detection signal of the second vibration detection unit The vacuum gauge is characterized in that the resonance state in the second vibration direction of the vibrating body is maintained . The vacuum gauge according to any one of claims 7 to 10 ,
The drive signal generation unit adjusts an amplification gain for a signal obtained by changing the phase of the detection signal of the vibration detection unit so that the voltage of the drive signal is constant,
The vacuum gauge according to claim 1, wherein the pressure measuring unit measures pressure based on a magnitude of a detection signal of the vibration detecting unit . The vacuum gauge according to any one of claims 7 to 10 ,
The drive signal generation unit adjusts an amplification gain for a signal obtained by changing the phase of the detection signal of the vibration detection unit so that the magnitude of the detection signal of the vibration detection unit is constant.
The vacuum gauge , wherein the pressure measuring unit measures pressure based on a voltage of the drive signal . The vacuum gauge according to any one of claims 7 to 12 ,
An initial excitation signal source for outputting an initial excitation signal having a frequency corresponding to the natural frequency of the vibrator;
A vacuum gauge , wherein an initial drive signal based on the initial excitation signal is applied to the excitation electrode unit instead of a drive signal based on a detection signal of a vibration detection unit when the vibrating body is initially driven . The vacuum gauge according to any one of claims 7 to 13,
The said vibration detection part detects the vibration of the said vibrating body by detecting the electrostatic capacitance between the said vibrating body and a detection electrode, The vacuum gauge characterized by the above-mentioned .

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