JPH07146192A - Pressure sensor - Google Patents

Abstract

PURPOSE:To measure line pressure and face pressure with a high resolution and a high accuracy by arranging a plurality of distortion-sensing elements consisting of a distortion-sensing resistor and a pair of electrodes in one- dimensional or in two-dimensional matrix on a flexible insulation base. CONSTITUTION:A glass powder layer with a specific composition is formed and calcined on a metal plate 1 to form a crystallization glass layer 2. Gold paste is screen-printed and calcined on a base 3 consisting of the metal plate 1 and the glass layer 2, thus forming a pair of electrodes 4, 4 and a pair of lead parts 5, 5. A resistor paste is screen-printed and calcined between the electrodes 4, 4 to form a resistor 6. In this manner, a distortion-sensing element consisting of the electrodes 4, 4 and the resistor 6 is arranged in a matrix on the flexible base 3, thus measuring the pressure distribution on a one- dimensional line or that on a two-dimensional plane with a high resolution and a high accuracy by a simple method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor for easily measuring a pressure distribution on a one-dimensional line or a two-dimensional plane.

[0002]

2. Description of the Related Art Conventionally, pressure sensors used in industry, especially sensors for analog linear pressure measurement,
Si semiconductor type sensors are the mainstream. In this sensor, for example, as shown in FIG. 4, a resistance layer 21 is formed by doping a Si substrate 20 having a thickness of 10 μm with nitrogen or the like, and a pair of electrodes 22 is formed on the resistance layer 21 to form a strain sensitive element. Resin layer 2
3 is joined to the main body 24. Arrow 2 on this
When a pressure is applied as in No. 5, the Si substrate 20 is deformed and the resistance layer 21 is distorted, and as a result, the resistance value changes according to the pressure change and outputs. In the sensor shown in FIG. 5, a constantan resistance layer 31 is formed on a polyimide resin substrate 30, which is attached to an object to be detected with an adhesive.
The resistance value change of the resistance layer 31 corresponding to the deformation of the polyimide resin substrate 30 due to the pressure is detected through the electrode 32.

[0003]

In order to measure the pressure distribution on a one-dimensional line or a two-dimensional surface with a conventional pressure sensor, a plurality of sensors are arranged in a matrix and the distribution of change in resistance value is measured. You have to measure. The Si semiconductor pressure sensor described above has a large shape, a complicated structure, and a complicated electric circuit. Therefore, the size is inevitably large. On the other hand, the one using a polyimide resin substrate has a problem in long-term reliability because it has to be adhered to the object surface. In either case, the wiring for extracting the signal from the matrix-shaped resistors becomes complicated, and it is virtually impossible to measure the one-dimensional or two-dimensional pressure distribution using these conventional sensors.

[0004]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems and provides a plurality of strain sensitive elements each including a strain sensitive resistor and a pair of electrodes on a flexible insulating substrate. The pressure sensor is characterized by arranging the pieces in a one-dimensional or two-dimensional matrix. Here, the insulating base material is preferably a metal plate and a glass layer formed on the surface thereof. Further, the strain sensitive resistor is preferably composed of a mixed layer of ruthenium oxide and glass.

In particular, the glass is preferably a crystallized glass composed of an amorphous glass layer made of borosilicate glass and a Ca—Mg—O type partial crystal layer deposited in the amorphous glass layer. Since this crystallized glass has a heat resistance temperature of 900 ° C. or higher, it can be easily formed on the glass layer by printing or drawing using a resistance paste with a firing temperature up to about 900 ° C. and subsequent firing. .

Further, the metal plate forming the glass layer has a coefficient of thermal expansion (100
˜140) × 10 ⁻⁷ / ° C. stainless steel is preferred.
The electrode of the resistor and the lead portion thereof can be easily formed on the glass layer by printing or drawing a conductive paste such as silver paste or platinum pesto and subsequent firing.

[0007]

According to the present invention, the pressure distribution on the one-dimensional line and the pressure distribution on the two-dimensional plane can be measured with high resolution and high reliability by a simple method.

[0008]

EXAMPLES Examples of the present invention will be described below. As shown in FIG. 1, 200 μm thick stainless steel SUS304
A glass powder layer having the composition shown in Table 1 is formed by electrophoretic electrodeposition on the substrate 1 made of, and subsequently baked at 900 ° C. to form a crystallized glass layer having a thickness of about 70 μm.

[0009]

[Table 1]

A gold paste is screen-printed on the base material 3 consisting of the metal plate 1 and the crystallized glass layer 2 as described above.
By firing at 0 ° C., the pair of electrodes 4, 4 and their lead portions 5, 5 are formed. Then, the resistor 6 is formed between the electrodes 4 and 4. The resistor 6 is formed by screen-printing a resistor paste made of ruthenium oxide and glass powder and subsequently firing at 850 ° C. In this way, as shown in FIG. 2, strain sensitive elements including the electrodes 4 and 4 and the resistor 6 are arranged in a matrix on the flexible base material 3. Note that, in FIG. 2, the lead portion 5 is simply represented by a line. Further, the entire surface is covered with an overcoat layer 7 made of a fluororesin and having a thickness of about 10 μm.

In this embodiment, the size is 20 cm × 20 c.
A matrix of 100 strain sensitive elements in total of 10 rows in the horizontal direction and 10 columns in the vertical direction is formed on the base material of m. When, for example, a human hand is placed on this pressure sensor, the pressure applied to the 100 strain sensitive elements depends on the shape of the hand. As a result, the distribution of the resistance values of the matrix-shaped strain sensitive element represents the shape of a human hand.

FIG. 3 shows an example in which a sensor 10 in which strain sensitive elements are one-dimensionally arranged on a strip-shaped base material is arranged on the floor portion 11 of the bed by using the same material as that of the first embodiment. The overturned state and sleeping state of the person lying on this can be constantly monitored by the pressure distribution, and by actively feeding back this, it is possible to obtain data for prevention of bedsores of the elderly and the sick, for example. it can.

The sensor of the above embodiment has a very simple structure including the lead portion of the strain sensitive element, and the measurement accuracy is ±
About 5% can be easily obtained. Further, when the resistor is formed by drawing and firing the resistance paste, the measurement accuracy can be increased to about ± 1%. In the example,
The substrate made of a metal plate and a glass layer was used as the resistor, and the resistor was made of ruthenium oxide. However, for example, a flexible ceramic plate may be used as the substrate and a constantan film may be used as the resistor. Is possible,
It is not limited to the above. Further, not only the pressure but also the measurement of strain or the like becomes possible by using the present sensor.

[0014]

According to the present invention, by forming a strain sensitive element in a one-dimensional or two-dimensional manner on a base material having an arbitrary shape, it is possible to measure linear pressure and surface pressure with high resolution and high accuracy. A sensor is obtained. The shape of the sensor for this purpose is much smaller and simpler than the conventional example, and the circuit can be simpler.
Until now, it is possible to open new applications such as bed bedsore prevention, which was impossible in the past.

[Brief description of drawings]

FIG. 1 is a sectional view showing a two-dimensional surface pressure measuring sensor of the present invention.

FIG. 2 is a plan view showing a schematic configuration of the sensor.

FIG. 3 is a perspective view showing a bed using the one-dimensional pressure measuring sensor of the present invention.

FIG. 4 is a sectional view of a conventional Si semiconductor pressure sensor.

FIG. 5 is a perspective view showing a conventional polyimide substrate type strain sensor.

[Explanation of symbols]

 1 Metal Plate 2 Glass Layer 3 Insulating Substrate 4 Electrode 5 Lead Section 6 Resistor 7 Overcoat Layer

Claims (3)

[Claims] 1. A pressure characterized in that a plurality of strain-sensitive elements each comprising a strain-sensitive resistor and a pair of electrodes thereof are arranged in a one-dimensional or two-dimensional matrix on a flexible insulating substrate. Sensor. 2. The pressure sensor according to claim 1, wherein the insulating base material comprises a metal plate and a glass layer formed on the metal plate. 3. The pressure sensor according to claim 1, wherein the strain sensitive resistor comprises a mixed layer of glass and an oxide of ruthenium.