JP2007155359A - Pressure sensitive container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To configure a pressure sensor in consideration of the structure of the pressure sensor, which simplifies the structure of a sensor system and makes the system compact. <P>SOLUTION: In order to solve problems, a structure is provided wherein a plurality of (two or more) support members with height are anchored so as to keep their distances to the principal plane of one side of a plate-like substrate which deforms in its thickness direction in response to an external pressure so that its fixed section becomes the supporting point, and a sensing member is fixed to the head of the support member. When the support substrate is applied with an external force along a direction parallel to its thickness direction and is deformed, the head of the support member is deformed in a direction perpendicular to the external force, i. e. , distances between heads of the support members are varied. As a result, an expansion or contraction force (stress) is applied to the sensing member. A change in the stress is sensed by measuring a frequency, a resistance, reflection of light or the like, thereby enabling an exact detection using a simple structure to be carried out at a low cost. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pressure sensor container that achieves simplification of the structure of a sensor system and miniaturization of the system in the structure of a pressure sensor.

  In recent years, with the realization of the ITS concept, interest in automobile safety has increased. Amid such circumstances, accidents caused by air pressure problems such as tire bursts on expressways, etc., are likely to involve surrounding vehicles and develop into major accidents, and it is essential to monitor tire pressure while driving. This pressure sensor was developed from such a social background and necessity.

In recent years, many semiconductor pressure sensors using silicon MEMS are used in the market because of the simplicity of the manufacturing method. In many of these sensor structures, a silicon wafer is thinned (diaphragm) using a MEMS processing technique to form a concave structure, and is fixed to the bottom of the package to constitute a chamber. The fluctuation of the thin wall due to the pressure change of the air to be measured introduced into this space is detected as a change in resistance value through a piezoresistor built on the back of the thin wall.
In addition, the applicant has not found any prior art documents related to the present invention by the present application other than the prior art documents specified by the prior art document information described above.

As an example of a pressure sensor that measures the pressure of a fluid that is generally used, FIG. 4 shows a sensor that detects a pressure by a mechanical operation. In FIG. 4, there is a bar linked to a double diaphragm that is deformed by pressurization, and the pressurization amount is detected by reading the operation change amount of the bar.
The straight movement (variation amount) of the rod is converted into a rotation mechanism using a rack and pinion mechanism, and the amount of change is displayed by a pointer attached to the rotation mechanism.

  In such a system, there is a high possibility that the entire apparatus is large, the mechanism is complicated, and the entire system price is expensive.

  In addition, in the pressure sensor using silicon MEMS, if the non-measurement air is contaminated because the air to be measured (air in the environment) is in direct contact with the thin wall that serves as the sensing unit, the contamination in the chamber This may cause a problem of sensitivity deterioration due to adhesion / accumulation and deterioration of temperature characteristics. In addition, since the processing accuracy such as the thin wall thickness of the diaphragm and the built-in piezoresistor directly reflects the variation in product characteristics, the sensor output value is used in the production process that configures the system. However, there is a problem that increases the cost even in such wages.

  In order to improve the above-described current problems, the present invention provides a plurality of (two or more) support bodies having a height on one principal surface of a plate-like substrate that deforms in the thickness direction according to external pressure with a fixed portion as a fulcrum. ), Which has a structure in which the distance is fixed and the sensing member is fixed to the tip of the support, and when the support substrate is deformed by an external force parallel to the plate thickness, the tip of the support is external force Deformation in the direction orthogonal to the angle, that is, the distance between the tips of the support bodies fluctuates, and as a result, stretching force (stress) is applied to the sensing member. By sensing this change in stress using frequency, resistance value, light reflection, etc., it is possible to accurately detect the change with a simple structure and at a low cost.

  As an example of the present invention, when a cylindrical pressure sensor container having a sealed container structure is formed by joining the entire outer periphery (fixed part) of the support substrate and the edge part of the concave structure base, the shape is, for example, a disk shape. Concavities and convexities and corrugated structures are constructed according to the external pressure (pressure) sensitivity, and two support bodies having a height are placed on one side of the main surface at an appropriate distance from the center of the circle. Separate and stick. In addition, this support body is a structure that has been treated according to the nature of the sensing member, such as securing a conductive portion to the outside while performing insulation treatment with the surroundings such as a substrate if electrical conduction is required. Become.

Then, if an elastic resistor whose resistance value changes according to the stretching force is selected as a sensing member, after fixing both ends of the elastic resistor to the tip of the support, the periphery of the concave base (edge) and the support substrate Join and seal the outside. In addition, if the pressure change is known by the frequency change, it is possible to use a piezoelectric vibrator such as an AT cut of a quartz crystal as a sensing member and observe the frequency change caused by the stress change between the two fixed points.
In addition, it is desirable to seal an inert gas having a constant pressure in accordance with the external pressure in the sealed container, and when the sensor element is in the container, this is a measure for minimizing changes with time. In this way, the structure in which the sensor element is confined in the hermetic container is effective when the type of fluid is in contact with the sensor element such as a liquid.

  On the other hand, the method of constructing the support (sensor element) on the inside of the container has been described so far, but as an example of measuring by placing it on the outside of the container, a fluid pressure such as clean gas or low vacuum is measured. In this case, when the support substrate is deformed, the support is fixed to a portion where the main surface of the substrate is inclined, and a reflector such as Kagami is fixed to the tip. In this case, only one support may be used, and a pressure change can be detected by irradiating the reflector with a light beam such as laser light from the outside and detecting a change in the reflected light.

  As described above, the fluid pressure sensor container according to the present invention has a simple structure, so that the manufacturing cost can be reduced, and the pressure transmission structure is simple and is directly transmitted to the sensor unit. No pressure sensor can be realized. As the external pressure, the external pressure amount can be accurately detected when an external force is directly applied to the support substrate in addition to a fluid such as gas or liquid. In this case, if the support substrate surface on which the sensor element is mounted is directly fixed on the surface of the object to be measured that causes the bending, the bending of the surface of the object to be measured is directly applied to the substrate. Since the board is deformed and the distance between the supports changes, the expansion and contraction force is generated at the support part of the sensor element. Therefore, external force changes can be detected without adding a concave base. It can also be used as a pressure sensor.

  Embodiments of the present invention will be described below with reference to the drawings. Sensor elements mounted between the supports (2) include silicon (using changes in piezoresistance), single crystal piezoelectric vibrators (using changes in frequency and resonance resistance), and elastic resistors (using elasticity). Sensor element forms such as dispersion of resistance powder in organic material and the resistance value changes between the two points according to external force when pressure is applied) and capacitance (capacitance change between opposing support electrodes) it can. Although not shown in the figure, it is also possible to use a change in the reflection angle of the light beam by fixing the reflector on one support as described above.

  FIG. 1 is a cross-sectional view illustrating an outline of a case where a plurality of supports are used as the fluid pressure sensor of the present invention. A support substrate 1 is manufactured using an elastic thin plate material such as a metal material, a ceramic material, or a glass material, and two support bodies 2 having a certain height are fixed to one side of the main surface, and sensors are arranged at respective vertex positions. The element is fixedly held. As described above, since most of the sensor elements are methods for electrically detecting a change in external force, the structure is such that an electrode can be taken out of the two supports independently so as not to cause an electrical short circuit.

  Then, for the purpose of generating deformation of the support substrate in response to the fluid pressure change, a concave base 4 structure formed by recessing using an elastic material is manufactured, and this outer peripheral portion and the support substrate outer peripheral portion are joined to each other. A sealed structure (chamber) is formed with fulcrum as a fulcrum. The unevenness and corrugated shape constructed on the main surface of the support substrate is a means for drawing out the maximum sensitivity corresponding to the magnitude of the pressure, and its dimensions and pitch are designed according to the pressure to be sensed.

  The support vessel shape of the pressure vessel is preferably circular so that pressure is applied to the plate surface and deformed evenly, and the construction position of the support is preferably constructed at a point-symmetrical distance from the center of the circle. At times, sufficient simulation analysis can be used to increase the degree of freedom of shape.

  When such a chamber is formed and installed in a fluid, the support substrate is fixed with a height to the support substrate because the center of the support substrate fluctuates in the thickness direction with the outer periphery as a fulcrum due to fluctuations in fluid pressure. The apex of the supporting body has a displacement in a direction parallel to the main surface of the substrate, and is transmitted to the sensor element as an expansion / contraction force via the joining member, and changes in frequency and resistance depending on the type of the sensor element. It can be detected by a change in value.

  FIG. 2 is a schematic diagram showing the concept of the pressure detection method of the present invention based on FIG. Note that, for the sake of explanation by the model, the drawing is performed by paying attention to the operation of the support 2 constructed on the main surface of the support substrate 1, and the distance between the vertices of the two supports 2 changes due to the external force applied to the support substrate 1. FIG. 2 (a) to FIG. 2 (c) show the state to be performed.

  That is, when the external pressure is larger than the internal pressure of the chamber, the central portion of the support substrate 1 is deformed so that the central portion of the support substrate 1 is recessed with both ends corresponding to the outer peripheral portion as fulcrums as shown in FIG. When the space between the supports 2 is widened and, conversely, when the external pressure is small relative to the internal pressure of the chamber, the support substrate 1 similarly has both ends corresponding to the outer periphery as fulcrums as shown in FIG. Since the central portion is deformed so as to swell and the distance between the two supports 2 is reduced, the expansion and contraction force according to a change in external pressure acts on both ends of the sensor element mounted on the tip of the support by the joining member. It is shown that.

Therefore, the sensor element arbitrarily selected according to the situation receives the expansion / contraction force, and the pressure state can be detected by changing the frequency value, resistance value, capacitance value, etc. according to the magnitude.
In addition, the support substrate to which an external force is directly applied is not limited to the flat plate of FIG. 3A for the purpose of maximizing the sensitivity, but the deformation is maximized as shown in FIGS. 3B and 3C. It is also necessary to change the plate thickness concentrically around the central portion to make it uneven, or to process it so as to generate effective deformation according to the sensed pressure by processing it into a corrugated shape.

  As described above, the present invention is based on the structure in which the sensor element is attached to the support constructed on the main surface of the support substrate. If the back surface of the support substrate is fixed to the non-measurement object as it is, the non-measurement object If an external force is applied to the tube and it is deformed, it can be used as a “deflection sensor” that detects the degree of the deformation. Furthermore, the outer periphery of the support substrate is joined to the outer periphery of the concave base to form an airtight chamber. We propose a “pressure sensor container” having a structure that can be used as a “pressure sensor” that can detect the fluid pressure when inserted into the environment. In this case, it is desirable that the positional relationship with the sensor element to be supported by the support 2 is a form in which the side surface of the sensor element is held.

The conceptual diagram of the airtight type pressure vessel of this invention is shown. The schematic diagram which shows the operation | movement of external force transmission and detection by this invention is shown. The example of a cross-sectional shape of the support substrate form of this invention is shown. The conceptual diagram which shows an example of the conventional mechanical pressure detection system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support substrate 2 Support body 3 Pressure vessel 4 Concave base

Claims (4)

A structure in which a plurality of support bodies whose heights can be adjusted are fixed on a principal surface in one direction of a plate substrate at a distance, and a part of the outer periphery of the plate substrate or the entire outer periphery is fixed. When an external force is applied in the thickness direction of the substrate, it has a structure that deforms so as to warp in the thickness direction according to the external force with the fixed portion as a fulcrum (fixed end), and the apex of the support is orthogonal to the external force direction A pressure-sensitive container having a support substrate that changes in the direction of movement and changes the apex position of the support. 2. The plate-like substrate according to claim 1, further comprising: a support substrate in which thick portions and thin portions are alternately constructed concentrically around a portion on the main surface where displacement due to an external force is maximum. container. 2. The pressure-sensitive container according to claim 1, further comprising a support substrate that has been subjected to corrugated processing in a concentric manner around a portion on the main surface where displacement due to an external force is maximum. 4. The pressure sensitive container according to claim 1, wherein the outer periphery of the substrate is a fixed part, and the fixed part and the edge of the concave base are joined and fixed to form an airtight structure.

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