JP3106939B2 - Capacitive pressure detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a diaphragm which is deformed in response to pressure and detects a displacement of the diaphragm from a change in capacitance formed between the diaphragm and a fixed electrode provided opposite to the diaphragm. The present invention relates to a capacitance type pressure detecting device.

[0002]

2. Description of the Related Art FIGS. 7 and 8 show a conventional example of such a capacitance type pressure detecting device (see Japanese Patent Publication No. 6-1228). In FIG. 7,
Reference numeral 1 denotes a pressure detecting unit main body, 2 denotes a diaphragm made of a silicon substrate, and 3a and 3b denote fixed electrodes, which are opposed to the diaphragm 2 at a predetermined distance (d) to form capacitances C1 and C2, respectively. . Reference numerals 4a and 4b denote insulating substrates for holding the fixed electrodes 3a and 3b while insulating them from the diaphragm 2, and hermetically fixing the diaphragm 2 and the glass bonding layers 6a and 6b around the periphery via supporting members 5a and 5b. Reference numerals 7a and 7b denote electrode plates for taking out the fixed electrodes 3a and 3b to the outside of the insulating substrates 4a and 4b. The fixed electrodes 3a and 3b are fixed to the insulating substrates 4a and 4b and then fixed to the insulating substrates 4a and 4b by a method such as sputtering. Conductor thin films are formed on the inner surfaces of the pressure guiding holes 8a and 8b penetrating the electrode plates 4a and 4b and the electrode plates 7a and 7b to conduct electricity.

When the pressure detecting unit main body 1 is configured as a differential pressure gauge, as shown in FIG. 8 , it is sealed in pressure transmitting media 10 and 11 such as silicon oil, and is connected to the main body case 12 at the pressure guiding hole 8a side, for example. Fixed. The pressure of the measurement fluid is transmitted from the seal diaphragms 13a and 13b to the diaphragm 2 via the pressure transmission media 10 and 11. Pressure transmission medium 10,
The reason for using 11 is mainly to protect the diaphragm 2 from excessive pressure. When excessive pressure is applied, the seal diaphragm 13a or 13b collides with the receiving portion 14a or 14b provided on the case 12 and is further displaced. Therefore, only a certain amount of pressure is applied to the diaphragm 2. However, when such oil is filled, the above-mentioned capacitances C1 and C2 depend on the dielectric constant of the oil, and if this changes with temperature or pressure, an error occurs.

As a method of correcting the error, for example, the displacement of the diaphragm 2, that is, the pressure is measured without being affected by the dielectric constant of the oil by calculating the measured values of the capacitances C1 and C2 by the following equation. be able to. (C1−C2) / {(C1 + C2) −2Ck)} = Δ / d (1) C1 = ε0 · ε · S / (d−Δ) = Ck C2 = ε0 · ε · S / (d + Δ) = Ck .. (2) where Ck: parasitic capacitance generated between conductors other than the electrodes Δ: displacement of the diaphragm 2 S: electrode area d: distance between the diaphragm 2 and the fixed electrode 3a or 3b ε0: relative dielectric constant of oil Rate ε: Vacuum permittivity.

[0005]

The effect of changing the dielectric constant of the pressure medium with temperature and pressure can be eliminated by performing the calculation as in the above equation (1). There are the following problems in performing the measurement. That is, in the measurement of the high-pressure fluid, the entire distance between the diaphragm 2 and the fixed electrode 3a or 3b decreases because the entire detection unit main body 1 receives a compression pressure from the surroundings, and the capacitance increases on both sides. When this variation is represented by δ, the above (2)
The equation is as shown in the following equation (3). C1 = ε0 · ε · S / (d−Δ−δ) = Ck C2 = ε0 · ε · S / (d + Δ−δ) = Ck (3) Therefore, the above equation (1) is obtained by the following equation (4). Δ depending on the pressure cannot be eliminated. (C1−C2) / {(C1 + C2) −2Ck)} = Δ / (d−δ) (4)

Similarly, when the temperature of the pressure transmitting media 10 and 11 changes, the distance between the diaphragm 2 and the fixed electrode 3a or 3b expands and contracts, and the capacitance changes in the same direction. Appears and an error occurs when measuring with high accuracy. For this reason, a method of performing correction by providing a temperature sensor or a pressure sensor is known in the art. As a relatively simple method for avoiding this, there is a method as shown in FIG. 9 (SENSORS June 19).
95, pp32, 33, 48, 49 "SmartPre
sure Sensors for Industry
ial Application ").

In FIG. 9 , reference numeral 21 denotes a sensor diaphragm and reference numeral 22 denotes a reference diaphragm, which are formed on a single silicon substrate 23. The former has a differential pressure to be measured, and the latter has one differential pressure. Are guided to both sides of the diaphragm, and are not deformed by the differential pressure. According to U.S. Pat. No. 4,794,320 described in the above document, the capacitance of the sensor diaphragm 21 is Cs, the capacitance of the reference diaphragm 22 is Cr, the circuit is Is the parasitic capacitance composed of other input capacitances including Cp, the period of the transmission frequency determined by Cp and Cs is Ts, the period of the transmission frequency determined by Cp and Cr is Tr, and the period of the transmission frequency determined by Cp, Cs and Cr is Tb, and the feedback resistance of the oscillator is Rf, which is corrected by the following equation.

Ts = (Cs + Cp) × Rf Tr = (Cr + Cp) × Rf Tb = (Cr + Cs + Cp) × Rf (5) From equation (5), Tb−Tr = Cs × Rf Tb−Ts = Cr × Rf Ts + Tr− Tb = Cp × Rf (6) Here, Cs = ε0 · ε · S / (d−Δ) Cr = ε0 · ε · S / d (7) From the equation, (Cr / Cs) −1 = Δ / d (8), and the capacitance Cr of the reference diaphragm 22
The displacement of the sensor diaphragm 21 is obtained by calculating the ratio between the sensor diaphragm 21 and the capacitance Cs of the sensor diaphragm 21.

However, in the configuration shown in FIG. 9 , although the influence of the parasitic capacitance Cp commonly applied to the sensor diaphragm 21 and the reference diaphragm 22 can be eliminated, the parasitic capacitances of the individual diaphragms (that is, the diaphragms) The capacitance between the diaphragm fixed part and the surrounding conductor, which does not change due to the displacement of this, is unavoidable due to its structure.)
There is a problem that compensation cannot be made because r and Cs themselves change. Accordingly, the present invention has been made to solve the above-mentioned drawbacks, and has an object to enable low-cost and highly accurate pressure measurement.

[0010]

In order to solve such a problem, according to the first aspect of the present invention, fixed electrodes are arranged at predetermined intervals on both sides of a conductive diaphragm which deforms in response to pressure. At least one capacitance-type pressure detecting means for forming a pair of capacitances with the diaphragm;
Absolute pressure detecting means for detecting an absolute pressure from a change in capacitance, temperature detecting means for detecting an ambient temperature including a diaphragm from a change in capacitance, the capacitance type pressure detecting means, and an absolute pressure detecting means And selecting means for sequentially selecting the temperature detecting means, and a correction calculating means for correcting the detected pressure based on the detected absolute pressure and temperature ,
The temperature detecting means is formed on a dielectric substrate and one surface thereof.
Consisting of a pair of comb-shaped electrodes that mesh with each other
And the comb-shaped electrode surface is contacted with the capacitance type pressure
Insulation that sandwiches the substrate on which the diaphragm of the detection means is formed
On the board side, fix it to the wiring section provided on this insulating board.
Was it it said.

According to the second aspect of the present invention, fixed electrodes are arranged at predetermined intervals on both sides of a conductive diaphragm that is deformed in response to pressure, and a pair of capacitances is formed between the fixed electrodes and the diaphragm. Capacitance type pressure detection means, and either one of absolute pressure detection means for detecting absolute pressure from change in capacitance and temperature detection means for detecting ambient temperature including the diaphragm from change in capacitance, A dielectric constant detecting unit for detecting a dielectric constant of a surrounding fluid enclosing the capacitance type pressure detecting element; and a dielectric constant detecting unit for detecting any one of the capacitance type pressure detecting unit and the absolute pressure detecting unit or the temperature detecting unit. Selecting means for sequentially selecting the means, and the detected pressure,
It characterized in that a correction calculating means for correcting, based on the detected permittivity absolute pressure or temperature.

[0012] In the second aspect of the present invention, the dielectric material
The ratio detecting means sandwiches the substrate forming the diaphragm.
Formed on an electrically insulated member including an insulating substrate
Can be composed of interdigitated interdigital electrodes
(Invention of claim 3) or the dielectric constant detecting means comprises:
Formed a diaphragm of the capacitance type pressure detecting means
At the fixed part on the periphery of the substrate, connect the diaphragm substrate or
Forming one of the sandwiched insulating substrates by spot facing
And the diaphragm substrate inside this space.
A fixed electrode provided on the surface of the insulating substrate;
Use the communication port for introducing the surrounding fluid and the inner surface of this communication port.
And the lead electrode for guiding the fixed electrode to the outside
(The invention of claim 4). Claim 1 or 2
In the present invention, the absolute pressure detecting means is provided with the capacitance
Formed on the substrate on which the diaphragm of the quantitative pressure detection means is formed
And other diaphragms
Fixed electrodes arranged at a predetermined interval on one of the surfaces
And the space between the other diaphragm and the fixed electrode is evacuated.
And the fixed electrode is hermetically sealed to the outside.
And a lead electrode to be taken out.
Item 5).

[0013]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, reference numeral 31 denotes a silicon substrate on which a diaphragm 32 is formed by plasma etching from both sides. The diaphragm 32 has a flat portion 33 slightly thinner than the substrate 31 at the center and an annular thin portion 34 on the outer periphery. 35a and 35b are substrates made of an insulating material having a thermal expansion coefficient substantially equal to that of the silicon substrate 31 such as Pyrex glass, and are hermetically bonded to the periphery of the silicon substrate 31 by a method such as electrostatic bonding. Gaps 36a and 36b are formed in the gap.

The diaphragm 3 of the insulating substrates 35a and 35b
The fixed electrodes 37a and 37b in which two layers of Cr / Au are laminated by a method such as sputtering are formed on the portions facing the flat portions 33 of the second.
Is formed, and a capacitor C is provided between the diaphragm 32 and the capacitor C.
1, C2 are formed. 38a and 38b are gaps 36a,
36b is a pressure guiding port that communicates with the outside. This impulse port 3
Electrodes 39a and 39b are provided by a method such as sputtering on the inner surfaces of the inner surfaces 8a and 38b and the outer surfaces of the insulating substrates 35a and 35b so as to surround the pressure guiding ports 38a and 38b.
a, 37b.

Numeral 40 is a pressure detecting means, and numeral 41 is a space (vacuum chamber) formed by processing the silicon substrate 31 by plasma etching to a depth substantially equal to the flat portion 33 of the diaphragm 32. An electrode 42 is provided on the surface of the insulating substrate 35a facing the gap 41, and is electrically connected to an electrode 44 provided on the outer surface of the insulating substrate 35a via a lead electrode formed on the inner surface of the hole 43. 32, a capacitance C3 is formed. Further, an insulating substrate 45 is air-tightly bonded on the electrode 44 by a method such as diffusion bonding or electrostatic bonding in a vacuum atmosphere, and the inside of the gap 41 is maintained at a vacuum. Note that the substrate 45 is not limited to an insulating material.

Reference numeral 46 denotes a temperature detecting means. Reference numeral 47 denotes an electrode provided on the outer surface of the insulating substrate 35a, and a capacitance C4 is formed between the electrode and the silicon substrate 31 with the insulating substrate 35a interposed therebetween. Reference numeral 48 denotes a base for holding the detection unit 1, 4
Reference numeral 9 denotes an insulating plate for insulating the electrode 39b from the base 48.
Each is fixed by a known method such as adhesion or bonding. Reference numeral 50 denotes an opening provided for electrically connecting the silicon substrate 31. The silicon substrate 31 is electrically connected to the electrode 51 through the inner surface of the opening 50 by a method such as sputtering.

In the configuration shown in FIG.
The magnitude relation between P1 and P2 is arbitrary, but for convenience, P1 <P
The description will be made taking the case of 2 as an example. Now, P
When a pressure difference of 1, P2 (P1 <P2) is applied, the diaphragm 32 is displaced in the direction of the arrow. The amount of this displacement can be obtained by detecting the capacitances C1, C2 and calculating the equation (1). As described above, the dielectric constant of the pressure transmitting fluids 10 and 11 can be obtained without being affected by a change due to temperature or pressure. When pressure is applied, the portion of the insulating substrate 35a forming the wall surface of the vacuum chamber 41 is deformed by the pressure P2, and the capacitance C
Since 3 changes, a signal corresponding to the absolute value of the pressure is obtained. Here, if there is a change in the temperature, a void is formed in the silicon substrate 3
Although the pressure sensitivity changes depending on the thermal expansion of 1, the pressure sensitivity can be made sufficiently large by the dimensions of the vacuum chamber 41 and the insulating substrate 35a, so that the pressure can be detected independently of the temperature.

The temperature change changes the dielectric constant of the insulating substrate 35a. That is, in materials such as Pyrex glass,
Generally, the dielectric constant increases in proportion to the temperature, and the capacitance C4
Changes. Although the thickness of the insulating substrate 35a is reduced by being compressed by the pressure, the influence on the capacitance is so small as to be negligible. The capacitance C4 is affected by the change in oil permittivity due to electric lines of force leaking into the surrounding pressure transmission medium. This is prevented by separating the electrode 47 from the end of the insulating substrate 35a sufficiently. As a whole, the pressure dependency of the capacitance C4 is very small. Therefore, by calculating the capacitances C1 and C2 by the calculation means 54 shown in FIG. 2 and performing a predetermined correction calculation on the result based on the pressure and temperature obtained from the capacitances C3 and C4, a highly accurate calculation can be performed. Measurement becomes possible.

At this time, as shown in FIG.
If the two detection circuits 52 are switched by the switching circuit 53, there is an advantage that a dedicated circuit becomes unnecessary and the cost is reduced as compared with a method of providing another correction sensor. In addition,
FIG. 2 shows a capacitance detection circuit 52 and a capacitance switching circuit 5.
3 and calculating means 54 of the detected capacitances C1 to Cn
And the like. In FIG. 1, one differential pressure detecting means is provided, but two or more differential pressure detecting means can be provided. In this way, it is possible to cope with different pressure differences, and it is possible to further increase the sensitivity.

FIG. 3 is a block diagram showing a first embodiment of the present invention. FIG. 3A is a top view, and FIG.
It is a side sectional view. The difference from the one shown in FIG. 1 is that the temperature detecting means 46 is provided on one surface of the dielectric substrate 55 with a pair of comb-shaped electric
It is formed by a capacitor provided with the poles 58a and 58b , and is fixed to the wirings 57a and 57b provided on the insulating substrate 35a. In this example, the electrode is a pressure transmitting fluid (10, 1).
Since there is little contact with the pressure transmitting fluid (1)
0, 11) is less affected by a change in the dielectric constant, and
It has the advantage that the production and mounting of electrodes is easy and cost can be reduced.
You. Also in this example, the capacitor for temperature detection is 35b.
Can be formed on the side .

FIG. 4 is a block diagram showing a second embodiment of the present invention. This differs from that shown in FIG.
As the degree detecting means, the diaphragm 3 is provided on the silicon substrate 31.
2 to the same depth as the flat portion 33
This is the point that the third gap 59 is provided. This void
Surface of insulating substrate 35a facing silicon substrate 31 of 59
Is provided with an electrode 62, and a hole formed on the inner surface of the opening 61.
An electrode provided on the outer surface of the insulating substrate 35a is connected via a ground electrode.
It is electrically connected to the pole 63 and has an electrostatic
The capacitance C5 is formed.

The surrounding pressure transmitting fluid 11 is introduced into the space 59.
Therefore, even if the surrounding pressure changes, the insulating substrates 35a,
35b and the silicon substrate 31 were not deformed.
Accordingly, the capacitance C5 is induced by the pressure transmitting fluid 11 therebetween.
Depends on electric power. That is, pressure transmission with temperature and pressure
The dielectric constant of the fluid 11 can be detected. Capacitance C
5 is for compressive deformation at high pressure and expansion and contraction due to temperature.
However, these are different from the effects of the pressure transmission medium.
All are very small and can be ignored.

On the other hand, the capacitance C3 is as described above.
In addition, since it is a function of only pressure and does not depend on temperature, C5 and
Extract signals that depend only on temperature by calculating
Can be. This example is directly similar to the first and second embodiments.
Obtain temperature information by calculation instead of detecting contact temperature
Although the function relationship between capacitance and temperature is
Because it is governed by the characteristics of the body 11,
It has the same temperature dependence as the capacitances C1 and C2. Pressure transmission
The dielectric constant of silicon oil used in the fluid, Ho low temperature side
In contrast to the non-linear characteristic with a large rate of change,
In the second embodiment, since a dielectric is used,
Non-linear characteristics with smaller change rate on the side, need to be corrected
There is a drawback that temperature detection accuracy is low in a wide temperature range,
In the example of FIG. 4, there is an advantage that the correction accuracy does not change in the temperature range.
Will have points.

FIG . 5 shows a modification of FIG. FIG.
(A) is a top view, and (B) is a side sectional view. Sand
Means for detecting the dielectric constant of the pressure transmitting fluid 11 is insulated.
Etching or the like of the comb-shaped uneven portion 64 on the surface of the substrate 35a
And comb electrodes 65a, 65b on the surface.
To form a capacitance C5 between the two electrodes. Electrodes are insulated
It has a capacitance through the surface of the substrate 35a, but has a comb electrode
The gap between 65a and 65b is reduced and the insulating substrate 35a
By increasing the depth of the groove of the uneven portion 64 of the
The dielectric constant of the pressure transmitting fluid 11 between 65a and 65b
The structure is determined. This makes the electrode fabrication insulated
Since it is only necessary to process the surface of the substrate 35a, manufacturing is easy.
There is an advantage that cost is reduced.

FIG. 6 shows a modification of FIG. 1 or FIG . Figure
1 or FIG. 4 is different from the silicon substrate 3 shown in FIG.
1 by means of plasma etching, etc.
66 in that the pressure detecting means formed at 66 is used. This example
In this case, the processing of the silicon substrate 31 becomes complicated.
4 compared to using the insulating substrate 35a as a diaphragm.
Using silicon with excellent mechanical strength as the diaphragm
Therefore, there is an advantage that manufacturing is easy and reliability is improved.
You. 4 and 5, the absolute pressure detecting means and the dielectric
Ratio detection means, but the temperature detection means
Needless to say, an electric power detecting means may be provided.
Nor.

[0026]

According to the present invention, the following effects can be obtained.
You can expect. (1) According to the first aspect of the present invention, a die that is deformed according to pressure is provided.
Place fixed electrodes on both sides of the
To detect the capacitance on both sides and change the capacitance.
Detection means for directly detecting temperature and pressure from
Switch each of these capacitances appropriately and measure with one device
Diaphragm and parasitic capacitance
The effect of the dielectric constant of the pressure transmitting fluid on
Now compensates for direct effects of temperature and pressure
As a result, parasitic parts other than the diaphragm
Unlike those that only compensate for capacity,
The advantage that high-precision measurement is possible in the range is obtained. Special
In addition, a temperature detecting means is provided on one surface of the dielectric substrate with a pair of comb teeth.
Electrode by forming a capacitor with
Not only makes it easier to work and mount, but also
Because the contact area can be reduced,
The advantage that the influence which can be reduced can be obtained.

Also, as in the conventional device, it is based on other principles.
Pressure and temperature sensors
Detects temperature and pressure from changes in capacitance based on the same principle
So that the capacitance detection value is switched and measured.
New detection means is unnecessary,
Can be reduced. In the invention of claims 2 to 5,
Detection means for detecting temperature and pressure from changes in capacitance
And the dielectric constant of the pressure transmitting fluid
Provision of detection means to detect temperature and pressure
To correct. In other words, the dielectric constant of the pressure transmitting fluid is directly detected
Temperature change in the dielectric constant of the pressure transmitting fluid
The advantage of being able to correct the effects of
You.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a block diagram illustrating a signal processing circuit of FIG. 1;

FIG. 3 is a partial configuration diagram showing the first embodiment according to the present invention.

FIG. 4 is an overall configuration diagram showing a second embodiment according to the present invention.

FIG. 5 is a partial configuration diagram showing a modified example of FIG.

FIG. 6 is a configuration diagram showing a modified example of FIG . 1 or FIG .

FIG. 7 is a partial configuration diagram showing a conventional example .

FIG. 8 is an overall configuration diagram showing a conventional example.

FIG. 9 is a configuration diagram showing another conventional example.

[Explanation of symbols]

1 ... pressure detection unit main body, 2, 32, 66 ... diaphragm,
3a, 3b, 37a, 37b ... fixed electrodes, 4a, 4b,
35a, 35b: insulating substrate, 5a, 5b: support member, 6
a, 6b: glass bonding layer, 7a, 7b: electrode plate, 8a,
8b: pressure guide hole, 10, 11: pressure transmitting fluid, 12: case, 13a, 13b: seal diaphragm, 14a, 1
4b: receiving portion, 21: sensor diaphragm, 22: reference diaphragm, 23, 31: silicon substrate, 3
3 flat part, 34 thin part, 36a, 36b, 41, 5
9: air gap, 38a, 38b: pressure guiding port, 39a, 39b,
42, 44, 47, 51, 56a, 56b, 58a,
58b, 62, 63, 65a, 65b: electrodes, 40: absolute pressure detecting means, 43, 61: holes, 45: substrate, 46:
Temperature detecting means, 48: base, 49: insulating plate, 50, 61
... Opening, 52, Detection circuit, 53, Switching circuit, 54, Calculation means, 55, Dielectric substrate, 57a, 57b, Wiring, 64
... Uneven portions.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kimihiro Nakamura 1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (56) References JP-A-60-61637 (JP, A) JP-A-7-7161 (JP, A) JP-A-62-24120 (JP, A) JP-A-3-175329 (JP, A) JP-A-59-4177 (JP, A) JP-A-3-175329 (JP) JP-A-5-52692 (JP, A) JP-A-5-332867 (JP, A) JP-A-6-66658 (JP, A) JP-A-60-128321 (JP, A) JP-A-60-128321 US Pat. No. 4,625,560 (US, A) US Pat. No. 4,741,214 (US, A) US Pat. No. 5,623,102 (US, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) G01L 9/12

Claims (5)

(57) [Claims] 1. A fixed electrode is disposed at a predetermined interval on both sides of a conductive diaphragm that is deformed in response to pressure, and at least one capacitance that forms a pair of capacitances with the diaphragm. Pressure detection means, absolute pressure detection means for detecting an absolute pressure from a change in capacitance, temperature detection means for detecting the ambient temperature including the diaphragm from a change in capacitance, the capacitance pressure detection selecting means for sequentially selecting the unit absolute pressure detecting means and the temperature detecting means, the detected pressure, and a correction calculating means for correcting based on the detected absolute pressure and temperature, said temperature detecting means, the dielectric Body substrate and formed on one side
Consisting of a pair of comb-shaped electrodes that mesh with each other
And the comb-shaped electrode surface is contacted with the capacitance type pressure
Insulation that sandwiches the substrate on which the diaphragm of the detection means is formed
A capacitance type pressure detecting device, which is fixed to a wiring portion provided on the insulating substrate on the substrate side . 2. A conductive diaphragm which deforms in response to pressure.
Fixed electrodes are arranged at predetermined intervals on both sides of the ram,
Capacitance that forms a pair of capacitance with the diaphragm
Capacitive pressure detecting means and absolute pressure detecting means for detecting absolute pressure from change in capacitance
Ambient temperature including diaphragm from step and capacitance change
And a temperature detecting means for detecting the dielectric constant of the surrounding fluid enclosing the capacitance type pressure detecting element.
Dielectric constant detecting means for detecting the ratio, the capacitance type pressure detecting means and the absolute pressure detecting means or
One of the temperature detecting means and the dielectric constant detecting means are sequentially
Selection means for selecting, the detected pressure, the detected dielectric constant and absolute pressure or
Correction calculation means for correcting based on temperature.
Characteristic capacitance type pressure detector. 3. The apparatus according to claim 2 , wherein said permittivity detecting means comprises:
Electrically isolated, including the insulating substrate that sandwiches the substrate that forms the
Interdigitated comb-shaped electrodes formed on an edged member
The capacitance type pressure detecting device according to claim 2, wherein 4. The method according to claim 1, wherein said permittivity detecting means is a capacitance type.
Fixing of the periphery of the substrate on which the diaphragm of the pressure detecting means is formed
In the fixed part, the diaphragm substrate or the insulating
A gap formed by counterboring one of the plates and the surface of the insulating substrate facing the diaphragm substrate inside this gap
A fixed electrode provided on the surface, a communication port for introducing a surrounding fluid into the gap, and guiding the fixed electrode to the outside by using an inner surface of the communication port.
And a lead electrode.
The capacitance-type pressure detection device according to claim 1. 5. An apparatus according to claim 5, wherein said absolute pressure detecting means is provided with said capacitance.
Formed on the substrate on which the diaphragm of the pressure detection means is formed
A predetermined distance between the other diaphragm and one surface of the other diaphragm.
The space between the fixed electrode and the other diaphragm and the fixed electrode is maintained in a vacuum.
And a lead electrode for taking out the fixed electrode to the outside in an airtight manner.
3. The method according to claim 1, wherein
The capacitance-type pressure detection device according to 1.