JP2000292295A - Inner pressure sensor for enclosed container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain detailed characteristics stably through a simple structure. SOLUTION: The sensor 11 formed on the bottom face part and representing the inner pressure variation of an enclosed container in the form of a strain comprises a thin film magnetic material layer 31 having magnetostriction formed on a substrate 21 of nonmagnetic plate, a planar coil 51 of conductor formed in the center of the substrate 21 through an insulation layer 41, and I/O terminals 61, 71 at the opposite ends of the coil 51. Since the variation in the inductance of the coil 51 caused by variation in the permeability of the thin film magnetic material layer 31 having magnetostriction corresponds to the magnitude of a generated strain, the magnitude of the generated strain can be detected from the variation of oscillation frequency, when the substrate is deformed. In particular, when the bottom face part is shaped to have a center and a substrate being formed at the bottom face part is a circle or a right polygon having a matched center, the coil is preferably formed annularly in spiral or meander line shape according to the anosotropy of the thin film magnetic material layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for detecting the internal pressure of a closed container which is formed on a substantially flat bottom surface of the closed container and detects a change in the internal pressure of the closed container by distortion of the bottom portion. The present invention relates to a sensor for detecting the internal pressure of an airtight container having a simple structure and capable of obtaining stable characteristics.

[0002]

2. Description of the Related Art Conventionally, as a sensor for detecting the internal pressure of a closed vessel of this type, a so-called strain gauge whose resistance value changes due to strain has been known as means for detecting deformation of a bottom surface.

FIG. 4 is a structural view showing an example in which a sensor 10 for detecting an internal pressure is mounted on a closed container 1. FIG. 5 is a perspective view showing an example of a strain gauge 110 used as the sensor 10 in FIG.

[0004] As shown in FIGS. 4 and 5, a strain gauge 110 as a pressure detection sensor is adhered to the center of a plate-like upper bottom portion 2 of a cylindrical hermetic container 1. The strain gauge 110 is formed in a flat shape on the surface of the upper bottom portion 2 by a thin film pattern of a linear conductor 130 made of an iron-nickel alloy.

Here, the principle of detecting the internal pressure of the closed vessel 1 by the strain gauge 110 will be described. Here, a strain gauge 110 is adhered to the upper bottom portion 2 of the closed container 1, and the thickness of the upper bottom portion 2 is more functionally satisfactory and safe than the lower bottom portion 3 and the side surface 4 of the closed container 1. It is assumed that the thickness is slightly thinner in the range.

When the internal pressure of the sealed container 1 increases from the normal state, the upper and lower bottoms 2, 3 and the side surface 4 of the closed container 1 are deformed so as to expand, while when the internal pressure decreases from the normal state. The upper and lower bottom portions 2 and 3 and the side surface 4 of the closed container 1 are deformed so as to be dented.

This deformation is caused by the upper bottom 2 having a smaller thickness.
Focus on The linear conductor 13 is formed on the plane of the linear conductor 130 in which the strain gauge 110 is formed by a thin film pattern.
The resistance value of the linear conductor 130 changes when strain is applied in the length direction of 0, that is, in the case where the wires are formed by connecting parallel lines. When the internal pressure of the closed container 1 changes, first the upper bottom 2 is deformed, and then the strain gauge 110 bonded to the upper bottom 2 is similarly deformed.
As a result, the input / output terminals 140, 1
Since the electric resistance between 50 changes, the change in the internal pressure of the sealed container 1 is detected by extracting the change in the electric resistance from the input / output terminals 140 and 150.

Such a strain gauge 110 is formed by forming a thin metal film having a resistance value changed by strain as a linear conductor 130 on a surface of a thin substrate 120 such as polyimide by vapor deposition or the like. The substrate 120 is bonded to a position where the strain is detected by using an adhesive.

Further, as another strain detecting means for detecting deformation of the facing surface in the closed container, a metal plate having a material and a shape for detecting the deformation of at least one of the facing surfaces is disposed, and the deformation of the metal plate is detected. In some cases, a change in the distance between the opposing metal plates is detected as a change in capacitance between two electrodes.

[0010]

In the conventional sensor for detecting an internal pressure in the above-mentioned conventional closed vessel, the former using a strain gauge, the strain gauge is bonded to a thin plate whose strain is to be detected using an adhesive. Because of the necessity, the detection characteristics change due to variations in the bonding position or the thickness of the bonding layer, and there is a problem that the characteristics need to be checked each time bonding is performed.

[0011] Further, in the case of using opposed metal plates, it is necessary to maintain the positional relationship between the two plates with high accuracy, and there is a problem that the structure becomes complicated.

An object of the present invention is to solve the above problems and to provide a sensor for detecting the internal pressure of an airtight container having a simple structure and stable characteristics.

[0013]

A sensor for detecting the internal pressure of a closed container according to the present invention is formed on a substantially flat bottom surface of the closed container, and detects a change in the internal pressure of the closed container by distortion of the bottom surface. A non-magnetic plate formed on the bottom surface, and an inductor formed substantially at the center of the non-magnetic plate and detecting a distortion of the non-magnetic plate by a change in inductance. .

According to this configuration, the strain at the bottom portion is converted into a change in inductance. Therefore, by incorporating the inductor as an element of the oscillation circuit, the magnitude of the strain can be easily converted into a change in oscillation frequency.

Preferably, the shape of the non-magnetic material plate is one of a circle and a regular polygon, and the inductor is provided on the surface of the thin film magnetic material layer having magnetostriction formed substantially at the center of the non-magnetic material plate. It has a configuration in which at least one coil is formed via an insulating layer.

The specific configuration of this coil is a helical linear conductor located substantially at the center of the non-magnetic plate, or a substantially central portion of the non-magnetic plate according to the anisotropy of the thin-film magnetic layer. It is preferable that the conductor is a linear conductor having an annular shape with a meander (meandering) line shape. With this configuration, it is possible to efficiently detect the deformation of the thin film magnetic layer accompanying the deformation of the bottom surface.

[0017]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view and a sectional view showing an embodiment of a sensor according to the present invention.

The sensor 11 shown in FIG. 4 for detecting the internal pressure of the closed container is the sensor 10 formed on the upper surface 2 of the closed container 1 shown in FIG.

Therefore, like the sensor 10 shown in FIG. 4, the sensor 11 has an upper bottom 2 and a lower bottom 3 which form a parallel plane.
Is formed on the surface of the bottom portion with the upper bottom portion 2 serving as a bottom surface portion having a somewhat thinner plate thickness and having a slightly thinner thickness. Detected by distortion.

In the sensor 11 shown in FIG. 1, a thin-film magnetic layer 31 made of a metal material having magnetostriction is formed on a main plane of a rectangular substrate 21 which is a nonmagnetic plate made of a metal material. A coil 51 of a meandering line made of a conductive material is formed in a rectangular shape in the center of the substrate 21, and input / output terminals 61, 71 with the outside are provided at both ends of the coil 51.
have.

In this configuration, when an external force acts on the substrate 21 to deform the substrate 21, the magnetic permeability of the thin film magnetic layer 31 having magnetostriction changes, and the inductance of the coil 51 changes. This change in inductance corresponds to the magnitude of the generated strain. Therefore, the magnitude of the generated strain can be detected from the change in the inductance. LC using the coil 51 as an L (inductance) element
By incorporating the distortion into the oscillation circuit, the magnitude of the distortion can be easily converted into a change in the oscillation frequency.

A rectangular meandering coil 51
As shown in FIG. 1, is formed by alternately connecting both ends of a large number of linear conductors arranged in parallel. The case where the substrate 21 on which the meandering-shaped coil 51 is formed is bent in a direction perpendicular to the length direction of the linear conductor to be the coil 51, that is, in the parallel arrangement direction, and in the length direction of the linear conductor The change in inductance between the case where the coil is bent in the direction parallel to that of the coil 51 differs depending on the material properties including the anisotropy of the thin film magnetic material having magnetostriction. However, in the shape of the coil 51 shown in FIG. It acts as a sensitive sensor for one axial deformation,
The sensitivity to the deformation in the axial direction that is perpendicular to this is much worse.

Therefore, in order to detect the deformation strain of a plate material deformed in a state where the periphery is fixed, it is necessary to make the coil shape conform to the strain distribution.

When the cross-sectional shape of the cylindrical airtight container is square or circular, the strain at the center of the plate-shaped bottom portion shows the maximum value, and the direction of the strain is radial from the center point and its size is large. Indicates a strain distribution represented by substantially concentric contour lines. Therefore, in order to efficiently detect such a deformation based on the strain distribution as a change in inductance, the strain distribution and the anisotropy of the magnetostrictive material used must be equal to the change in permeability in a direction parallel to the direction of strain. It is necessary to match the direction of the conductor of the coil with the direction of the strain depending on whether the direction of the coil is large or the change in the magnetic permeability in the direction perpendicular to the direction of the strain.

This is because when the magnetic permeability in the direction parallel to the strain direction is large, that is, when the change in the magnetic permeability is radial with respect to the center of the bottom plate, a concentric coil is suitable, If the permeability in the direction perpendicular to the direction of the above is large, that is, if the change in the permeability is concentric with the center of the bottom plate portion, it is appropriate that a coil with a meandering line shape formed in an annular shape is suitable. Is shown.

Next, a sensor using concentric coils will be described with reference to FIG.

In the sensor 12 shown in FIG. 2, a thin-film magnetic layer 32 made of a metal material having magnetostriction is formed on a main plane of a circular substrate 22 which is a non-magnetic material plate made of a metal material. A spiral coil 52 made of a linear conductor is formed at the center of the substrate 22, and both ends of the coil 52 have input / output terminals 62 and 72 with the outside.

An internal terminal 82 is provided at an inner end of the coil 52, and an insulating layer 92 is formed on the coil 52 so as to cover the upper surface. Input / output terminals 62, 7
2 is located above the insulating layer 92, and the internal terminal 82 is connected to the input / output terminal 72 through the upper surface of the insulating layer 92.

The sensor 12 having this configuration is formed on the bottom surface so that the center points thereof are aligned with each other, and an external force acts on the bottom surface and the substrate 22
Is deformed, the magnetic permeability of the thin film magnetic layer 32 having magnetostriction changes, and the inductance of the coil 52 changes.
Due to the change in the inductance of the spiral coil 52, it is possible to efficiently detect the deformation of the substrate 22 at the bottom of the closed container caused by the change in the pressure in the cylindrical closed container.

Next, a sensor using a meander-line shaped coil formed in a ring shape will be described with reference to FIG.

In the sensor 13 shown in FIG. 3, a thin film magnetic layer 33 made of a metal material having magnetostriction is formed on a main plane of a circular substrate 23 which is a non-magnetic material plate made of a metal material. A coil 53 of a meandering line shape made of a linear conductor is formed in an annular shape with the center point coincident with the center of the substrate 23, and has input / output terminals 63 and 73 with the outside at both ends of the coil 53. ing.

The sensor 13 having this structure is formed on the bottom surface so that the center points thereof coincide with each other.
Is deformed, the magnetic permeability of the thin film magnetic layer 33 having magnetostriction changes, and the inductance of the coil 53 changes.
Due to the change in the inductance of the coil 53 formed in an annular shape by the meandering line shape, it is possible to efficiently detect the deformation of the substrate 23 at the bottom portion of the closed container caused by the change in the pressure in the cylindrical closed container.

In the above description, the shape of the substrate made of the non-magnetic material plate is rectangular or circular, but it may be polygonal. However, in order to detect deformation efficiently, it is desirable that the bottom surface of the closed container has a shape having a center point, and the shape of the substrate of the sensor is a regular polygon including a circle or a square.

Further, in the above description, the closed container is cylindrical, but it is obvious that the present invention can be applied to any shape as long as it has a plate portion which is deformed according to the internal pressure.

[0036]

As described above, according to the present invention, a non-magnetic plate formed on a substantially flat bottom surface of a closed container and serving as a substrate, and a non-magnetic plate formed at a substantially central portion of the non-magnetic plate are provided. A sensor for detecting the internal pressure of a sealed container having an inductor for detecting the strain of the nonmagnetic plate by a change in inductance is obtained.

With this configuration, the strain on the bottom surface is converted into a change in inductance. Therefore, by incorporating the inductor as an element of the oscillation circuit, the magnitude of the strain can be easily converted into a change in oscillation frequency. Therefore, an effect is obtained that the distortion can be detected in detail and stably with a simple structure.

Further, according to the present invention, the shape of the non-magnetic material plate is one of a circle and a regular polygon, and the inductor is a thin-film magnetic material layer having magnetostriction formed substantially at the center of the non-magnetic material plate. A spiral wire having a configuration in which at least one coil is formed on the surface of the non-magnetic material layer via an insulating layer, and the coil is located substantially at the center of the non-magnetic material plate according to the anisotropy of the thin-film magnetic material layer It is possible to obtain a sensor that is a linear conductor or a linear conductor that forms an annular shape with a meandering line located substantially at the center of a nonmagnetic plate.

As a result, in particular, the bottom portion of the sealed container has a shape having a center point, and the shape of the substrate of the sensor attached to the bottom portion is also a regular polygon including a circle or a square, and the center points are matched. In this case, the effect is obtained that the deformation of the thin film magnetic layer accompanying the deformation of the bottom surface can be detected efficiently.

[Brief description of the drawings]

FIG. 1A is a plan view showing one embodiment of the present invention,
(B) is a sectional view of (A).

FIG. 2A is a plan view showing another embodiment different from FIG. 1, and FIG. 2B is a cross-sectional view taken along the line AA of FIG.

3A is a plan view showing another embodiment different from FIGS. 1 and 2, and FIG. 3B is a cross-sectional view of FIG.

FIG. 4 is a perspective view showing one embodiment of a closed container forming a sensor.

FIG. 5 is a perspective view showing an example of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Closed container 2 Top bottom part 10, 11, 12, 13 Sensor 21, 22, 23 Substrate (nonmagnetic plate) 31, 32, 33 Thin film magnetic layer 41, 42, 43, 92 Insulating layer 51, 52, 53 Coil 61, 62, 63, 71, 72, 73 Input / output terminal 82 Internal terminal

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Naoki Waka, 7-7-1, Koriyama, Taishiro-ku, Sendai-shi, Miyagi F-term (reference) 2F055 AA11 BB20 CC14 EE21 EE29 FF43 GG11 2F063 AA25 AA42 BA19 DA02 GA03 GA56 5E049 AA01 AA09 AC05 BA16

Claims (5)

[Claims] 1. A sensor for detecting an internal pressure of an airtight container, which is formed on a substantially flat bottom surface of the airtight container and detects a change in the internal pressure of the airtight container by distortion of the bottom surface. A sensor for detecting an internal pressure of a sealed container, comprising: a non-magnetic plate, and an inductor formed at a substantially central portion of the non-magnetic plate to detect distortion of the non-magnetic plate by a change in inductance. . 2. The sensor according to claim 1, wherein the shape of the non-magnetic plate is one of a circle and a regular polygon. 3. The inductor according to claim 1, wherein at least one coil is formed on a surface of a thin film magnetic layer having magnetostriction formed substantially at a central portion of the nonmagnetic plate via an insulating layer. A sensor for detecting an internal pressure of a sealed container, comprising: 4. The sensor according to claim 3, wherein the coil is a helical linear conductor located substantially at the center of the non-magnetic plate. 5. The internal pressure of an airtight container according to claim 3, wherein the coil is a linear conductor formed in an annular shape with a meandering line shape located substantially at the center of the nonmagnetic plate. Detection sensor.