JP2016191637A - Sensor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor module capable of suppressing a detection error.SOLUTION: A pedestal side electrode part 14 includes a center electrode 14M and an annular reference electrode 14R arranged apart from the outer peripheral edge of the center electrode 14M. A diaphragm side electrode part 15 has a common electrode 15C including a first electrode 15C1 facing the center electrode 14M and an annular second electrode 15C2 arranged apart from the outer peripheral edge of the first electrode 15C1 and facing the reference electrode 14R. Since the center electrode 14M faces the first electrode 15C1, and the reference electrode 14R faces the second electrode 15C2, there is a space where an electrode is not formed between the first electrode 15C1 and the second electrode 15C2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sensor module.

Some capacitive pressure sensors include a sensor module in which electrodes are provided on a pedestal portion and a diaphragm portion, respectively, and a capacitive capacitor is formed by these electrodes. In this pressure sensor, when the diaphragm portion is displaced by the pressure of the fluid to be measured, the capacitance between the electrodes changes, so that a pressure value converted accordingly is detected.
As a conventional example, a substrate and an elastic diaphragm disposed opposite to the substrate at a predetermined interval are provided. A circular center electrode and an annular reference electrode are formed on the substrate so as to be separated from each other. There is a capacitance type pressure sensor in which a common electrode having a diameter larger than that of a reference electrode is formed in a circular shape on an opposing surface (Patent Document 1).

As another conventional example, there is a capacitance type pressure sensor in which a diaphragm and a substrate are arranged apart from each other, and a measurement electrode and a reference electrode are formed on the surfaces facing each other (Patent Document 2). .
As another conventional example, there is a capacitance type pressure sensor in which a sensor diaphragm and a sensor pedestal are arranged apart from each other, and a plurality of fixed electrodes and a plurality of movable electrodes are separately formed on surfaces facing each other. Yes (Patent Document 3).

An example approximate to Patent Document 1 will be described with reference to FIGS.
FIG. 10 shows a cross section of the sensor module 100.
In FIG. 10, the sensor module 100 has a structure in which a pedestal portion 101 and a diaphragm portion 102 are joined to each other via a cylindrical joining glass 103. The pedestal portion 101 is provided with a pedestal side electrode portion 104. The pedestal side electrode portion 104 includes a central electrode 104M provided at the center of the pedestal portion 101, a reference electrode 104R provided on the outer peripheral side of the central electrode 104M, and a shield electrode 104S provided on the outer periphery of the reference electrode 104R. Have
A diaphragm side electrode portion 105 is provided in the diaphragm portion 102. The diaphragm side electrode unit 105 includes a common electrode 105C facing the pedestal side electrode unit 104, and a shield electrode 105S provided on the opposite side of the common electrode 105C with a shield coat 106 interposed therebetween.

A plan view of the pedestal 101 is shown in FIG. As shown in FIG. 11, the center electrode 104M is circular, and the reference electrode 104R and the shield electrode 104S each have an annular shape with the center of the circle of the center electrode 104M as a concentric circle.
The plane of the diaphragm portion 102 is shown in FIG. As shown in FIG. 12, the common electrode 105C has a circular shape, and the outer peripheral edge thereof is larger than the outer peripheral edge of the reference electrode 104R in plan view (see FIG. 10). Note that the central electrode 104M shown in FIG. 11 and the common electrode 105C shown in FIG. 12 are both hatched, but this does not show a cross section, and the configuration of these electrodes is easy to understand. belongs to.
In the sensor module 100 having such a configuration, the diaphragm portion 102 that receives pressure is bent, and a gap between the central electrode 104M and the reference electrode 104R provided in the pedestal portion 101 and the common electrode 105C provided in the diaphragm portion 102 is formed. Change, and this is detected as a change in capacitance.

When the electrostatic capacitance between the center electrode 104M and the common electrode 105C is Cm and the electrostatic capacitance between the reference electrode 104R and the common electrode 105C is Cr, the pressure conversion value K of the entire sensor module is as follows: Calculated based on an arithmetic expression.
K1 = Cm-Cr (1)
K2 = Cm / Cr (2)
K3 = (Cm-Cr) / (Cm + Cr) (3)

Japanese Patent No. 2815279 JP-A-8-285714 JP 2006-10539 A

  In the conventional example of Patent Document 1, the central electrode and the reference electrode must be secured to some extent due to restrictions on capacitance detection capability. In order to reduce the size of the sensor, these electrodes are close to each other. In addition, since the common electrode is formed over the entire plane of the diaphragm, in Patent Document 1, when detecting the capacitance, the capacitance generated between the central electrode and the common electrode, the reference electrode, There is a location that interferes with the capacitance generated between the common electrode.

That is, in the example shown in FIGS. 10 to 12, the common electrode 105C is formed as a solid surface on the same plane, and each of the static electrodes is located between the central electrode 104M and the reference electrode 104R that are close to each other. It is what forms a capacitance. Therefore, when the capacitance is detected, an interference location A is generated between the center electrode 104M and the reference electrode 104R.
In this interference location A, the range ratio of the common electrode 105C constituting the electrode changes due to changes in the surrounding environment (temperature, humidity, noise disturbance, etc.) and the end effect of the capacitor, so the apparent electrode area also changes. , Leading to detection errors.

Furthermore, the apparent area of the electrodes facing each other changes due to slight displacement of the electrode positions of the diaphragm portion 102 and the pedestal portion 101, the inclination of the bonding glass 103, and the difference in the bending method of the diaphragm portion 102. This causes variations in the characteristics of the sensor module.
Since the area of the reference electrode 104R needs to be set large in order to balance the capacitance due to the center electrode 104M, the deflection of the diaphragm portion 102 due to pressurization is directly affected by the change in capacitance. Therefore, the amount of change in the capacitance formed by the reference electrode 104R is large, and the output due to the change in the capacitance of the center electrode 104M thus obtained is expressed by the equations (1) to (3). Since it acts in the direction of decreasing, the output span decreases.

  In the conventional examples of Patent Documents 2 and 3, the electrode provided on the diaphragm and the electrode provided on the substrate are each composed of a plurality, but the reason for providing a plurality of these electrodes, There is no description regarding the shape of these electrodes. Patent Documents 2 and 3 do not find a description suggesting the problem of Patent Document 1 in which at least an interference location occurs due to the relationship between the electrode provided on the diaphragm and the electrode provided on the substrate.

  An object of the present invention is to provide a sensor module that can suppress detection errors.

  The sensor module of the present invention is provided in the diaphragm portion, a diaphragm portion provided in the pedestal portion, a pedestal side electrode portion provided in the pedestal portion, and opposed to the pedestal side electrode portion. A diaphragm side electrode portion, and one of the pedestal side electrode portion and the diaphragm side electrode portion is a central electrode disposed at a central portion and an annular shape disposed away from an outer peripheral edge of the central electrode. A reference electrode, the other of the pedestal side electrode portion and the diaphragm side electrode portion has a common electrode, and the common electrode includes a first electrode facing the center electrode, and a first electrode And an annular second electrode disposed away from the outer peripheral edge and facing the reference electrode.

  In the present invention, the center electrode and the first electrode face each other, the reference electrode and the second electrode face each other, and there is a gap where no electrode is provided between the first electrode and the second electrode. Interference between the capacitance generated between the electrode and the first electrode and the capacitance generated between the reference electrode and the second electrode can be reduced, and therefore detection errors of the sensor module can be suppressed. .

In this invention, the dimension between said 1st electrode and said 2nd electrode is the surface where the said base side electrode part of the said base part is formed, and the surface where the said diaphragm side electrode of the said diaphragm part is formed It is preferable that it is 10 times or more of the dimension between.
If the dimension between the first electrode and the second electrode is less than 10 times the dimension between the surface of the pedestal part and the surface of the diaphragm part, the effect of separating the first electrode and the second electrode is not sufficient. However, the degree of interference between the capacitances generated between the center electrode and the first electrode and between the reference electrode and the second electrode is increased, resulting in inconvenience in detection.

In the present invention, the second electrode preferably has a larger radial dimension than the reference electrode.
In this configuration, even if the diaphragm portion is attached by shifting from the position where the second electrode correctly faces the reference electrode, the capacitance generated between the center electrode and the first electrode, the reference electrode, There is little interference with the capacitance generated between the two electrodes.

In the present invention, it is preferable that a linear conductive portion is connected between the first electrode and the second electrode.
In this configuration, a sufficient effect as a common electrode can be obtained by electrically connecting the first electrode and the second electrode. Since the conductive part is linear, even if there is interference between the capacitance generated between the center electrode and the first electrode and the capacitance generated between the reference electrode and the second electrode, the amount is extremely small. Few.

In the present invention, it is preferable that a plurality of the conductive portions are arranged.
In this configuration, if there is only one conductive part, the first electrode and the second electrode cannot be electrically connected when the conductive part is cut. Even if it is done, since the first electrode and the second electrode are electrically connected by the remaining conductive portion, a sufficient effect as a common electrode can be obtained.

In the present invention, it is preferable that a shield electrode is provided on each of the inner peripheral side and the outer peripheral side across the reference electrode.
In this configuration, the interference of capacitance can be reduced due to the shielding effect. Moreover, it can be expected that the detection error due to the interference between the central electrode and the reference electrode due to high humidity is suppressed by the shielding effect by the shield electrode on the inner peripheral side.

In this invention, the said common electrode is formed in the insulating member provided in the surface facing the said base part of the said diaphragm part, The surface on the opposite side to the surface in which the said common electrode of the said insulating member was formed Is preferably provided with a shield electrode.
With this configuration, the interference effect can be reduced due to the shielding effect, and even if the wetted liquid is filled with a conductive substance such as water, the influence can be reduced and detection errors can be suppressed. I can hope. In addition, as described above, when shield electrodes are provided on the inner and outer peripheral sides with the reference electrode interposed therebetween, malfunctions and detection errors due to radioactive and conductive electromagnetic noise are caused by the interaction of these electrodes. I can hope to suppress it.

Sectional drawing which shows the sensor module of 1st Embodiment of this invention. The top view which shows the plane facing the diaphragm part of a base part. The top view which shows the positional relationship of a reference electrode and a hole. The top view which shows the plane facing the base part of a diaphragm part. The top view which expanded a part of diaphragm part. The figure which shows the sensor module of 2nd Embodiment of this invention, and is equivalent to FIG. The top view which shows the plane facing the diaphragm part of a base part. The top view which shows the positional relationship of a reference electrode and a hole. The figure which shows the sensor module of 3rd Embodiment of this invention, and is equivalent to FIG. Sectional drawing of the sensor module of the example approximated to patent document 1. FIG. The top view which shows the base part of the example approximated to patent document 1. FIG. The top view which shows the diaphragm part of the example approximated to patent document 1. FIG.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows the overall configuration of the sensor module 10.
In FIG. 1, a sensor module 10 is a pressure conversion element disposed inside a pressure sensor (not shown). In order to detect the pressure of the fluid to be measured, the pressure of the fluid to be measured is an electrical output signal. It is to convert to.
The sensor module 10 includes a pedestal portion 11, a diaphragm portion 12 disposed to face the pedestal portion 11, and a cylindrical bonding glass 13 disposed between the pedestal portion 11 and the diaphragm portion 12. Yes. The thickness dimension of the bonding glass 13 is L.

The pedestal portion 11 has a thick disk shape made of ceramic, and the outer diameter thereof is, for example, 30 mm. A pedestal-side electrode portion 14 is provided on the surface of the pedestal portion 11 that faces the diaphragm portion side. The pedestal side electrode portion 14 is formed by printing and applying an Ag—Pd paste on the flat surface of the pedestal portion 11 and then baking.
The pedestal side electrode portion 14 includes a central electrode 14M provided in the center portion, and an annular reference electrode 14R provided on the outer peripheral side of the central electrode 14M and on the inner peripheral side of the bonding glass 13. The central electrode 14M is a moving electrode, and the reference electrode 14R is a fixed electrode.
The center electrode 14M and the reference electrode 14R are covered with a glass coat 14G, and the outer peripheral edge of the glass coat 14G is bonded to the bonding glass 13.

The diaphragm portion 12 has a thin disk shape made of ceramic, and the outer diameter dimension thereof is equal to the outer diameter dimension of the pedestal portion 11. A common electrode 15 </ b> C is provided on the surface of the diaphragm 12 that faces the pedestal. The common electrode 15 </ b> C is formed by printing and applying a metal organic paste (for example, Au resinate) on the plane of the diaphragm portion 12 and then baking.
The common electrode 15C includes a first electrode 15C1 that faces the center electrode 14M, and an annular second electrode 15C2 that is arranged away from the outer peripheral edge of the first electrode 15C1 and faces the reference electrode 14R.
In the present embodiment, the diaphragm 12 is bent by the pressure of the fluid to be measured, so that the capacitance between the center electrode 14M and the first electrode 15C1 and the static between the reference electrode 14R and the second electrode 15C2 are increased. The pressure of the fluid to be measured is detected from the change from the electric capacity.

  In FIG. 1, hatching indicating a cross section of the pedestal portion 11 and the diaphragm portion 12 is omitted. Furthermore, although the pedestal side electrode portion 14 and the common electrode 15C are shown thick, this is for making the installation position of the pedestal side electrode portion 14 and the common electrode 15C easy to understand, and the actual thickness is The outer diameter of the pedestal 11 is extremely small. For example, the thickness of the pedestal side electrode portion 14 after firing is, for example, about 5 μm, and the thickness of the common electrode 15C after firing is about 0.5 μm. The dimension L between the surface 11B of the pedestal portion 11 where the pedestal side electrode portion 14 is formed and the surface 12B of the diaphragm portion 12 where the common electrode 15C is formed is about 10 μm.

FIG. 2 shows a plane of the pedestal 11 that faces the diaphragm 12.
In FIG. 2, the center electrode 14 </ b> M is a circle whose circle center coincides with the center of the pedestal 11. The diameter MD of the central electrode 14M is, for example, 7 mm.
The reference electrode 14R is disposed concentrically with the central electrode 14M. The reference electrode 14R is formed in an annular shape having an inner peripheral diameter RD1 of, for example, 18 mm and an outer peripheral diameter RD2 of, for example, 19 mm. No electrode is formed in the region between the inner periphery of the reference electrode 14R and the outer periphery of the center electrode 14M, and the glass coat 14G is formed directly on the plane of the pedestal 11 (see FIG. 1).

The pedestal 11 is formed with six holes 11A1 to 11A6 for forming through holes or introducing the air as needed. These holes 11A1 to 11A6 are formed through the pedestal 11.
The hole 11A1 is formed in the region of the central electrode 14M. The hole 11A1 is formed away from the center of the circle of the central electrode 14M in relation to a circuit (not shown) arranged on the opposite side of the pedestal 11.
The hole 11A2 is formed in a region between the inner periphery of the reference electrode 14R and the outer periphery of the center electrode 14M.
The hole 11A3 is formed so as to extend over the outer peripheral edge of the reference electrode 14R. The reference electrode 14R has an enlarged portion 14R1 formed concentrically with the center of the hole 11A3.
The hole 11A4 is formed away from the outer periphery of the reference electrode 14R in the radial direction in a direction opposite to the center electrode 14M of the hole 11A3.
The holes 11A5 and 11A6 are formed in regions where the bonding glass 13 is provided.

The positional relationship between the reference electrode 14R and the holes 11A3 and 11A4 is shown in FIG.
In FIG. 3A, the enlarged portion 14R1 in which the hole portion 11A3 is formed has a part of its inner peripheral edge protruding from the inner peripheral edge of the reference electrode 14R toward the center of the pedestal portion 11, and has an outer peripheral edge. The portion protrudes from the outer peripheral edge of the reference electrode 14R toward the outer diameter of the pedestal portion 11. The region where the bonding glass 13 is formed is cut in an arc shape so as to avoid the protruding portion of the enlarged portion 14R1.
In FIG. 3B, the hole 11A4 is formed away from the outer peripheral edge of the reference electrode 14R. The region where the bonding glass 13 is formed is cut in an arc shape so as to avoid the hole 11A4.

FIG. 4 shows a plane that faces the pedestal 11 of the diaphragm 12.
In FIG. 4, the first electrode 15 </ b> C <b> 1 is a circle whose circle center coincides with the center portion of the diaphragm portion 12. The diameter of the first electrode 15C1 is 7 mm, which is the same as the diameter MD of the central electrode 14M.
The second electrode 15C2 is disposed concentrically with the first electrode 15C1. The second electrode 15C2 has an inner peripheral diameter CD1 that is smaller than the inner peripheral diameter of the reference electrode 14R (for example, 17 mm), and an outer peripheral diameter CD2 that is the same as the outer peripheral diameter RD2 of the reference electrode (for example, 19 mm). is there. That is, the second electrode 15C2 is formed in an annular shape like the reference electrode 14R, but the radial dimension (width dimension) is set larger than the radial dimension of the reference electrode 14R. In the present embodiment, the configuration is not limited to the above-described configuration as long as the radial dimension of the second electrode 15C2 is set larger than the radial dimension of the reference electrode 14R. The outer diameter CD2 of 15C2 may be larger than the outer diameter RD2 of the reference electrode.

The dimension CD between the outer periphery of the first electrode 15C1 and the inner periphery of the second electrode 15C2 is a surface 11B on which the pedestal side electrode portion 14 of the pedestal portion 11 is formed and a surface on which the common electrode 15C of the diaphragm portion 12 is formed. It is 10 times or more of the dimension L between 12B. For example, when CD = (17 mm−7 mm) / 2 = 5 mm and L = 10 μm, the magnification is 500 times. When the ratio of the dimension L to the dimension CD is less than 10 times, the effect of separating the first electrode 15C1 and the second electrode 15C2 is not sufficient, and between the central electrode 14M and the first electrode 15C1, and the reference electrode The degree of interference between the capacitances generated between 14R and the second electrode 15C2 increases.
A linear conductive portion 15D is connected to the first electrode 15C1 and the second electrode 15C2. The conductive portion 15D is arranged so that two portions are linear with the first electrode 15C1 interposed therebetween. The dimension along the longitudinal direction of the conductive portion 15D is a dimension CD between the outer periphery of the first electrode 15C1 and the inner periphery of the second electrode 15C2, and the dimension (width dimension) orthogonal to the longitudinal direction is 0.3 mm. Degree.

An electrode extraction portion 15E is connected to a part of the outer peripheral edge of the second electrode 15C2. The electrode extraction portion 15E is formed along the longitudinal direction of the conductive portion 15D, and has a linear base portion 15E1 connected to the second electrode 15C2 and a tip portion 15E2 connected to the base portion 15E1. The dimension (width dimension) orthogonal to the longitudinal direction of the base part 15E1 is a value larger than the width dimension of the conductive part 15D, for example, 1 mm. The distal end portion 15E2 has a planar rectangular shape, and the width dimension thereof is larger than the width dimension of the base portion 15E1.
In the present embodiment, the diaphragm side electrode unit 15 includes the common electrode 15C, the conductive unit 15D, and the electrode extraction unit 15E.
The conductive portion 15D and the electrode extraction portion 15E are formed of the same material as the common electrode 15C and in the same procedure as the common electrode 15C. The thickness dimension of the conductive part 15D and the electrode extraction part 15E is the same as the thickness dimension of the common electrode 15C.

FIG. 5A shows an enlarged view of the electrode extraction portion 15E. In FIG. 5A, the connecting portion between the base 15E1 of the electrode extraction portion 15E and the second electrode 15C2 is a curved portion R. Similarly, a curved portion R is formed at a connection portion between the base portion 15E1 and the distal end portion 15E2.
FIG. 5B shows an enlarged view of the conductive portion 15D. In FIG. 5B, curved portions R are formed at the connection portions between the first electrode 15C1 and the second electrode 15C2 of the conductive portion 15D.

In the first embodiment, the following effects can be achieved.
(1) The pedestal side electrode portion 14 has a central electrode 14M and an annular reference electrode 14R arranged away from the outer peripheral edge of the central electrode 14M, and the diaphragm side electrode portion 15 has a common electrode 15C. The common electrode 15C includes a first electrode 15C1 that faces the center electrode 14M, and an annular second electrode 15C2 that is arranged away from the outer peripheral edge of the first electrode 15C1 and faces the reference electrode 14R. Since the center electrode 14M and the first electrode 15C1 face each other, and the reference electrode 14R and the second electrode 15C2 face each other, there is a gap where no electrode is formed between the first electrode 15C1 and the second electrode 15C2. Therefore, interference between the electrostatic capacitance generated between the center electrode 14M and the first electrode 15C1 and the electrostatic capacitance generated between the reference electrode 14R and the second electrode 15C2 can be reduced, so that the detection of the sensor module can be performed. Errors can be suppressed.

(2) The dimension CD between the first electrode 15C1 and the second electrode 15C2 is such that the surface 11B on which the pedestal side electrode part 14 of the pedestal part 11 is formed and the diaphragm side electrode part 15 of the diaphragm part 12 are formed. Since it is 10 times or more of the dimension L between the surface 12B, the effect of separating the first electrode 15C1 and the second electrode 15C2 is sufficient, and electrostatic charges are generated between the center electrode 14M and the first electrode 15C1. Interference between the capacitance and the capacitance generated between the reference electrode 14R and the second electrode 15C2 can be suppressed.

(3) Since the second electrode 15C2 has a larger dimension in the radial direction than the reference electrode 14R, even if the second electrode 15C2 is attached with a deviation from the position facing the reference electrode 14R, the central electrode 14M and the first electrode Interference between the electrostatic capacity generated between the reference electrode 14R and the second electrode 15C2 can be suppressed.

(4) Since the linear conductive portion 15D is connected to the first electrode 15C1 and the second electrode 15C2, a sufficient effect as the common electrode 15C can be obtained. Since the conductive portion 15D is linear, the capacitance generated between the center electrode 14M and the first electrode 15C1 and the capacitance generated between the reference electrode 14R and the second electrode 15C2 are also from this point. Interference can be suppressed.

(5) Since the conductive portion 15D is linear, the area of the conductive portion 15D provided between the first electrode 15C1 and the second electrode 15C2 can be reduced as compared with the case where the conductive portion 15D is curved. It is possible to suppress the interference of capacitance more effectively.

(6) Since the width dimension of the conductive portion 15D is smaller than the width dimension of the second electrode 15C2 and the minimum necessary width dimension, the area of the conductive portion 15D can be reduced from this point as well, Capacitance interference can be suppressed more effectively.

(7) Since the conductive portion 15D is linearly arranged at two locations across the first electrode 15C1, even if one of the two conductive portions 15D may be cut, the remaining 1 Since the conductive portions 15D at the locations are in a state where the first electrode 15C1 and the second electrode 15C2 are connected, the effect as the common electrode 15C can be made sufficient.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIGS.
The second embodiment is different from the first embodiment in that a shield electrode is provided on the pedestal portion 11, and the other configuration is the same as that of the first embodiment. In the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.
FIG. 6 shows the overall configuration of the sensor module 20 of the second embodiment, and corresponds to FIG.

In FIG. 6, the sensor module 20 includes a pedestal portion 11, a diaphragm portion 12, and a bonding glass 13. A pedestal side electrode portion 24 is provided on the surface of the pedestal portion 11 that faces the diaphragm portion side. The pedestal side electrode part 24 is formed by printing and applying an Ag—Pd paste on the flat surface of the pedestal part 11 and then baking it.
The pedestal side electrode portion 24 includes a shield electrode 24S in addition to the central electrode 14M and the reference electrode 14R.

FIG. 7 shows a plane facing the diaphragm portion 12 of the pedestal portion 11.
In FIG. 7, the shield electrode 24S includes an annular small-diameter shield electrode 24SA provided between the center electrode 14M and the reference electrode 14R, and an annular large-diameter shield electrode 24SB provided on the outer peripheral side of the reference electrode 14R. Prepare.
The small-diameter shield electrode 24SA is disposed concentrically with the central electrode 14M, and has an inner peripheral diameter SA1 of, for example, 7.5 mm and an outer peripheral diameter SA2 of, for example, 17 mm.
The large-diameter shield electrode 24SB is disposed concentrically with the center electrode 14M, and has an inner peripheral diameter SB1 of, for example, 20 mm and an outer peripheral diameter SB2 of, for example, 27 mm.
Electrodes are formed in the region between the central electrode 14M and the small-diameter shield electrode 24SA, the region between the small-diameter shield electrode 24SA and the reference electrode 14R, and the region between the reference electrode 14R and the large-diameter shield electrode 24SB, respectively. The glass coat 14G is directly formed on the plane of the pedestal 11 (see FIG. 6).

The positional relationship between the reference electrode 14R and the holes 11A3 and 11A4 is shown in FIG.
In FIG. 8A, the enlarged portion 14R1 in which the hole portion 11A3 is formed has a part of its inner peripheral edge protruding from the inner peripheral edge of the reference electrode 14R toward the center of the pedestal portion 11, and has an outer peripheral edge. The portion protrudes from the outer peripheral edge of the reference electrode 14R toward the outer diameter of the pedestal portion 11. The small-diameter shield electrode 24SA and the large-diameter shield electrode 24SB are cut in an arc shape so as to avoid the protruding portion of the enlarged portion 14R1.
In FIG. 8B, the hole 11A4 is formed away from the outer peripheral edge of the reference electrode 14R. The large-diameter shield electrode 24SB is cut in an arc shape so as to avoid the hole 11A4.

In the second embodiment, in addition to the same effects as (1) to (7) of the first embodiment, the following effects can be achieved.
(8) Since the shield electrodes 24SA and 24SB are provided on the inner peripheral side and the outer peripheral side, respectively, with the reference electrode 14R interposed therebetween, the interference of capacitance can be reduced due to the shielding effect.
(9) Even if high-humidity air is interposed between the center electrode 14M and the reference electrode 14R, it is blocked by the shielding effect by the small-diameter shield electrode 24SA on the inner peripheral side of the reference electrode 14R, so the influence is reduced. It is possible to suppress the detection error.

[Third Embodiment]
A third embodiment of the present invention will be described with reference to FIG.
The third embodiment is different from the second embodiment in that shield electrodes are provided not only on the pedestal portion but also on the diaphragm portion, and the other configurations are the same as those in the first embodiment and the second embodiment. In the description of the third embodiment, the same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.
FIG. 9 shows the overall configuration of the sensor module 30 of the third embodiment, and corresponds to FIG.
In FIG. 9, the sensor module 30 includes a pedestal part 11, a diaphragm part 12, and a bonding glass 13. A pedestal side electrode portion 24 is provided on the surface of the pedestal portion 11 that faces the diaphragm portion side.

A shield electrode 35 </ b> S is provided on the surface of the diaphragm 12 that faces the pedestal. The shield electrode 35 </ b> S is formed in a circular shape having the same outer diameter as the inner peripheral diameter of the bonding glass 13.
An insulating member 31 is provided on the entire surface including the plane of the shield electrode 35S on the surface of the diaphragm portion 12 on the pedestal portion side. The insulating member 31 is made of glass.
A common electrode 15C, a conductive portion 15D, and an electrode extraction portion 15E are provided on the surface of the insulating member 31 that faces the pedestal portion 11. In FIG. 9, the conductive portion 15D and the electrode extraction portion 15E are not shown. The planar shapes of the common electrode 15C, the conductive portion 15D, and the electrode extraction portion 15E are the same as those shown in FIG. In the present embodiment, the diaphragm side electrode portion 35 includes the shield electrode 35S, the common electrode 15C, the conductive portion 15D, and the electrode extraction portion 15E. The shield electrode 35S is formed in the same manner as the common electrode 15C, the conductive portion 15D, and the electrode extraction portion 15E.

In the third embodiment, in addition to the same effects as (1) to (9) of the second embodiment, the following effects can be achieved.
(10) The common electrode 15C, the conductive portion 15D, and the electrode extraction portion 15E are formed on the insulating member 31 provided on the surface of the diaphragm portion 12 facing the pedestal portion 11, and the common electrode 15C of the insulating member 31 is electrically conductive. Since the shield electrode 35S is provided on the surface opposite to the surface on which the portion 15D and the electrode extraction portion 15E are formed, the interference effect of the electrostatic capacity can be reduced due to the shielding effect, and the diaphragm portion 12 Even if the liquid contact side is filled with a conductive substance such as water, the influence can be reduced and detection errors can be suppressed.
(11) The central electrode 14M, the reference electrode 14R, and the diaphragm side electrode portion are constituted by the small diameter shield electrode 24SA and the large diameter shield electrode 24SB provided on the inner and outer peripheral sides with the reference electrode 14R interposed therebetween, and the shield electrode 35S. Since the detection unit consisting of 15 is wrapped with a shield potential, it is possible to suppress malfunctions and detection errors due to radioactive and conductive electromagnetic noise.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in each of the embodiments described above, the pedestal side electrode portion 14 includes the central electrode 14M and the reference electrode 14R, and the diaphragm side electrode portion 15 includes the common electrode 15C. The electrode unit 14 may include a common electrode 15C, and the diaphragm side electrode unit 15 may include a center electrode 14M and a reference electrode 14R.

  Further, the conductive portion 15D may not be linear but may be a curve. Furthermore, the conductive portion 15D is not necessarily provided. Even if it is a case where it provides, it is not limited to what provides the electroconductive part 15D in two places, Only one place or three places or more may be sufficient.

  DESCRIPTION OF SYMBOLS 10,20,30 ... Sensor module, 11 ... Base part, 12 ... Diaphragm part, 14, 24 ... Base side electrode part, 14M ... Center electrode, 14R ... Reference electrode, 15, 35 ... Diaphragm side electrode part, 15C ... Common Electrode, 15C1 ... first electrode, 15C2 ... second electrode, 15D ... conductive portion, 24S, 35S ... shield electrode, 31 ... insulating member

Claims (7)

A pedestal portion, a diaphragm portion provided in the pedestal portion, a pedestal side electrode portion provided in the pedestal portion, and a diaphragm side electrode portion provided in the diaphragm portion facing the pedestal side electrode portion; With
One of the pedestal side electrode portion and the diaphragm side electrode portion has a central electrode disposed in the central portion and an annular reference electrode disposed away from the outer peripheral edge of the central electrode,
The other of the pedestal side electrode part and the diaphragm side electrode part has a common electrode,
The sensor module, wherein the common electrode includes a first electrode facing the center electrode and an annular second electrode disposed away from an outer peripheral edge of the first electrode and facing the reference electrode. The sensor module according to claim 1,
The dimension between the first electrode and the second electrode is the dimension between the surface of the pedestal portion where the pedestal side electrode portion is formed and the surface of the diaphragm portion where the diaphragm side electrode is formed. A sensor module characterized by being 10 times or more. The sensor module according to claim 1 or 2,
The sensor module, wherein the second electrode has a larger radial dimension than the reference electrode. The sensor module according to any one of claims 1 to 3,
A linear conductive part is connected between the first electrode and the second electrode. A sensor module, wherein: The sensor module according to claim 4, wherein
The sensor module, wherein a plurality of the conductive parts are arranged. In the sensor module according to any one of claims 1 to 5,
A sensor module, wherein shield electrodes are respectively provided on an inner peripheral side and an outer peripheral side across the reference electrode. The sensor module according to any one of claims 1 to 6,
The common electrode is formed on an insulating member provided on a surface of the diaphragm portion facing the pedestal portion, and a shield electrode is formed on a surface of the insulating member opposite to the surface on which the common electrode is formed. A sensor module characterized in that is provided.

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