JPS61278729A - Pressure detecting device - Google Patents

Abstract

PURPOSE:To compensate easily temperature by employing two semiconductor materials having the similar characteristics as a resistance element and obtaining changes in their resistance ratios. CONSTITUTION:The titled device has the 1st and 2nd pressure sensors R1 and R4d2 made of semiconductors having the similar characteristics of resistance changes with respect to static hydraulic pressure. The 1st and 2nd pressure sensors R1 and R2 are disposed in the 1st container 1 packed with a pressure transmitting medium 2 and in the vicinity of a container including the 1st container 1, respectively. The pressure in the 2nd container 9 is made constant, and only temperature changes as the 1st container 1 does. The resistances of the 1st and 2nd pressure sensors R1 and R2 are ratio-calculated, and divided by a temperature signal, whereby the influence of temperature is eliminated and a signal in proportion to the pressure can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improving the sensitivity of a pressure detection device using a semiconductor and improving temperature compensation means.

[Conventional technology]

Most pressure detection devices using semiconductors as sensors utilize piezoresistance effects. In a sensor that utilizes this piezoresistance effect, stress changes occur within the semiconductor crystal due to strain caused by external force, and this changes the energy level of electrons. As a result, the resistance value changes.

Therefore, in order to obtain sufficient measurement sensitivity for the pressure to be measured by H1, the key point in designing a pressure detection device is how to apply distortion to the semiconductor pressure sensor. Generally, as shown in FIG. 5, a method is often used in which a semiconductor piezoresistive element 10 is bonded to a diaphragm 11.

(Problems to be Solved by the Invention) However, since the conventional pressure detection device as shown in FIG. 5 uses one semiconductor as a sensor, There were problems such as difficulty in eliminating the term □ (difficulty in temperature compensation) and inability to obtain a sufficient pressure-conductivity change (insufficient pressure sensitivity).

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure detection device that combines two pressure sensors each made of semiconductor and having substantially similar characteristics, has a simple structure, and is easy to correct for temperature.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention has first and second pressure sensors made of semiconductors having substantially the same resistance change characteristics with respect to hydrostatic pressure, and the first pressure sensor is connected to the first pressure sensor for pressure transmission. placed in a first container filled with medium;
A pressure sensor is arranged in the vicinity of the containers including the inside of the first container, and the pressure inside the second container is kept constant and only the temperature changes in the same way as in the first container.
By performing a ratio calculation on the resistance of the second pressure sensor and dividing it by the temperature signal, the influence of temperature is removed and a signal proportional to pressure is obtained.

〔Example〕

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a diagram showing an example of the main part configuration (pressure detection end) of a pressure detection device according to the present invention. In the same figure, 1 is the first
It is a container. 2 is a pressure transmission medium sealed in the first container 1, and for example, in the embodiment, silicone oil, which is an incompressible fluid, is used. R+ is the first pressure sensor made of a pressure-sensitive semiconductor material, such as InSb, whose resistance value changes to positive polarity in response to changes in applied hydrostatic pressure (such pressure-sensitive semiconductor materials As for materials, there are materials such as Garb and GaAS whose resistance value becomes positive with respect to an increase in pressure, and materials whose resistance value becomes negative such as black phosphorus, Se, Te, etc. For example, [n3b
The bandgap pressure coefficient (dEQ/dP) T is 15~
20X10' (ev/bar) and silicon is -0
, 3 to -1,5X10' (ev/bar) 11 degrees).

Reference numeral 9 denotes a second container disposed within the first container 1. A temperature transfer medium (silicone oil in the embodiment) 5 is sealed in the second container 9. A second pressure sensor +JR2 having substantially the same characteristics as the first pressure sensor is arranged. Reference numeral 12 denotes a space (preferably in a vacuum state) provided within the second container 9 to absorb the pressure increase due to thermal expansion of the temperature transfer medium. TC is a temperature detection element arranged in the first container 1, such as a thermal lightning pair, for example. Note that the lower temperature detection element C does not necessarily have to be placed inside the container 1, since it is for measuring the temperatures of the first and second pressure sensors R1 and R2. 4 is a hermetic seal part, and lead wires 68 to 8b are electrically connected to pressure sensors R+ and R2.
This is to prevent the pressure transmission medium 2 from leaking when taking it out of the first container 1.

Although not shown in the figure, this hermetic seal is the second hermetic seal.
This also applies when taking out the lead wire from the container 9. The pressure to be measured is applied to the portion 1a of the first container 1, but a diaphragm that is corrosion resistant and has a wide elastic range is provided to prevent the pressure transmission medium 2 sealed therein from flowing out.

FIG. 2 shows an electric circuit to which the lead wires 68 to 8b in FIG. 1 are connected, and from the output terminal of this circuit, a signal eout corresponding to the applied pressure can be obtained.

In FIG. 2, 20 is a constant voltage source, and U is an amplifier.

R+ is the resistance value of the first pressure sensor shown in FIG. 1, R2
Similarly, is the resistance value of the second pressure sensor. C is a logarithmic converter, D is a divider, and F is an adder.

The first pressure sensor R+ is connected to the inverting input terminal of the amplifier U, and the second pressure sensor R+ is connected between the output terminal and the inverting input terminal of the amplifier U.
pressure sensor R2 is connected.

A constant voltage source 20 is connected between the other end of the first pressure sensor R+ and the non-inverting input terminal of the amplifier U. The output terminal and non-inverting input terminal of amplifier U are connected to logarithmic converter C. Output voltage e2 of logarithmic converter C and output voltage (-A) of adder F
are connected in series and introduced into the divider. Further, a signal from the temperature detection element TO is introduced into another input terminal of the divider.

The operation of the pressure detecting device in which the pressure detecting end shown in FIG. 1 and the electric circuit shown in FIG. 2 configured as described above are combined will be described below.

The first and second pressure sensors shown in FIGS. 1 and 2 are made of intrinsic semiconductors having the same characteristics and sensitivity to hydrostatic pressure.
Adjust so that the pressure applied to both pressure sensors is the same. As a result, the first and second pressure sensors R+, R2
The electrical conductivity σ is expressed by equations (1) and (1).

σ−nL*e・(μe+μp) (1)(2)
Here, e is the electron elementary charge μ is the electron balance #J degree μp is the hole mobility In the equation (1), n is the intrinsic carrier power of the semiconductor material, which is expressed by the following equation.

Here, no is the temperature, Eo is the material constant that is not related to band energy, band gap energy T is the absolute temperature, K is the Boltzmann constant, and is the hydrostatic pressure of the semiconductor material.The resistance value, that is, the conductivity changes mainly because Band gap energy Eo
However, it varies depending on the pressure. The resistance value (R) of the pressure sensor due to pressure change is expressed by the following equation.

Here, C is a constant determined by the shape and dimensions of the pressure sensor Ro is a constant Therefore, the pressure sensors R+ and R2 are immersed in silicone oil as shown in Figure 1, and the pressure is applied to the first pressure sensor in the first container. When a change is given, the resistance 1a (represented as R+, R2) of each pressure sensor R+, R2 changes as follows.

When this is amplified by the amplifier U shown in FIG. 2, the output e1 of the amplifier U is expressed by equation (6).

Roλ ” ”” R#leo (
6) eo is the voltage of the constant voltage source 20.If the temperature inside the first container 1 shown in FIG. 1 is uniform, (
Equation (6) can be rewritten as Equation (7) using Equations (4) and (9).

921 e+ = eo −eXl” 1teT (Eo
2 Ea + ))12ri1...(7) As described above, by taking the resistance ratio (R2/R1), the first temperature shadow 1? A signal e1 with (T-■) deleted can be obtained.

When el is passed through a logarithmic variable 'Mk unit C, a signal e2 expressed by equation (8) is obtained.

e2=ln l e+ l Note that l1nQoz e, -A Ro+ When a constant signal of -A is added from the adder F to this e2 signal, the input to the divider is x*r (E G 2 E o + >.If this signal is divided by the humidity signal (1/ton) from the temperature detection element TC, a signal eout expressed by equation (9) is obtained.

eo uL = ac-(EG2 EG + )
(9) In this way, by using two pressure sensors made of pressure-sensitive semiconductor materials with substantially similar characteristics and placing one in a container where the pressure changes and the other in a container where the pressure does not change, a single pressure sensor can be used. FIG. 3 shows another embodiment of the pressure-sensitive semiconductor pressure sensor. The same elements as in Fig. 1 are given the same reference numerals and redundant explanations are omitted, but in this example, the second container is fixed to the outer wall of the first container, and one side of the container is open to the atmosphere. It is. In this case, temperature transfer within the second container takes place through the outer wall of the container. This example has the advantage that the structure can be simplified if the second pressure sensor is small and has a sufficiently small heat capacity.

, R+ and R2 are pressure sensors.

In addition, in FIG. 2, the first pressure sensor R+ is connected between the inverting input terminal of the amplifier U and the constant voltage source 20, and the second pressure sensor R2 is connected between the input and output terminals of the amplifier U. Although the explanation has been made assuming that the pressure sensors R+ and R2 are connected to each other, it is clear that the present invention can also be implemented by changing the connection arrangement of the pressure sensors R+ and R2.

〔Effect of the invention〕

As described above, according to the present invention, the following effects can be obtained.

(2) Temperature compensation can be easily performed by using two semiconductor materials having similar characteristics as resistive elements and determining the change in their resistance ratio.

■ No pressure transducer such as a diaphragm is required, simplifying the mechanical configuration.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the main part configuration of a pressure detection device according to the present invention, and FIG. 2 is a diagram showing each lead wire 6a to 8a shown in FIG. 1.
3 is a side view of the main part configuration of the pressure detection device showing another embodiment, FIG. 4 is a diagram showing an example where the amplifier U is not required, and FIG. Diaphragm 1
1 is a diagram showing a conventional means configured by bonding a semiconductor piezoresistive element 10 to a semiconductor piezoresistive element 1. DESCRIPTION OF SYMBOLS 1... First container, 2... Pressure transmission medium, 4...
Hermetic seal portion, 5... Temperature transmission medium, 68-
8b... Lead wire, 9... Second container, R1...
First pressure sensor, R2...Second pressure sensor, TC
...Temperature detection element, U...Additional 11/A unit, C...
Logarithmic variable Mka, D... depruritic device, F... numbing device. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A first container to which a pressure to be measured is applied and a pressure transmission medium sealed inside the container; and a first semiconductor disposed within the first container and whose resistance changes depending on the hydrostatic pressure. a pressure sensor, a second container disposed near the container including the inside of the first container, having a structure that is not affected by the hydrostatic pressure, and having a temperature transfer medium sealed therein; A pressure detection device comprising: a second semiconductor pressure sensor disposed in a container; and means for calculating a resistance ratio of the first and second semiconductor pressure sensors. (2) A temperature detection element for detecting the temperature inside the first container, and means for logarithmically converting the output signal of the means for calculating the resistance ratio, and a signal based on the signal obtained by the temperature detection element. 2. The pressure detection device according to claim 1, wherein the temperature component of the signal from the logarithmic conversion means is corrected using the following.