JPS60133334A - Pressure sensor - Google Patents

Abstract

PURPOSE:To obtain a highly sensitive pressure sensor, which is hardly affected by the vibration noises and attitude change, by providing a force feedback means, which receives the displacement of a movable plate or a signal from a torque detecting means and imparts the force corresponding the signal to the movable plate. CONSTITUTION:Electrostatic capacity CX between electrodes 71 and 72, which are provided on the fixed plate 4 and a movable plate 62 is detected by an electrostatic-capacity measuring circuit 73, and a voltage eX corresponding to CX is outputted. An adder circuit 74 obtains the difference epsilon between the voltage signal eX from the electrostatic-capacity measuring circuit 73 and the voltage signal eX corresponding to initial capacity C0 (a state where pressures P1 and P2 are zero). The difference value is imparted to an amplifier 75. The amplifier 75 imparts the output to a coil 8, which is provided on the movable plate 62. The voltage corresponding to a current flowing the coil 8 is measured by a meter 77. Torque is generated in the movable plate 62 by the current flowing the coil 8. The torque is sent in the direction reverse to the direction of torque generated by the pressure difference between the pressures P1 and P2, i.e., the torque of the plate 62 is negatively fed back. Thus the movable plate 62 is balanced so that the input voltage epsilon of the amplifier 75 becomes zero. The pressure difference between P1 and P2 can be found as the displayed value on the meter 77. Thus the highly sensitive pressure sensor, which is hardly affected by vibration noises and attitude change can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a pressure sensor that detects pressure changes as displacement or torque of a movable plate. More specifically, the present invention relates to a pressure sensor that is particularly effective for use in measuring minute pressures such as, for example, 0.01 pm water column.

[Description of prior art]

Conventionally, a condenser microphone is known as a pressure sensor capable of measuring minute pressure. This device consists of a metal membrane that receives pressure and a constant electrode placed opposite to this metal membrane. It is detected as follows.

However, this device has the problem that unless the metal film is stretched so that the tension is uniformly reduced over the entire surface, detection sensitivity will vary and good characteristics cannot be obtained. Also, since the detection sensitivity is high, it has the disadvantage that it is susceptible to single vibration noise and posture changes.

[Object of the present invention]

The present invention has been made in view of these problems and shortcomings in the prior art, and aims to realize a highly sensitive pressure sensor that has a simple configuration, is less susceptible to vibration noise and changes in posture.

[Summary of the invention]

The device according to the present invention includes a fixed plate having slots and holes, a movable plate placed opposite the fixed plate to which pressure to be measured is applied, and a straight line passing through the center of gravity of the movable plate so that the movable plate can rotate. a support section that supports the movable plate at two points; a detection means that detects the displacement or torque of the movable plate; and a force feedback means that inputs a signal from the detection means and applies a force to the movable plate according to the signal. Consists of.

[Explanation based on examples]

FIG. 1 is a sectional view showing an example of the pressure sensor according to the present invention, FIG. 2 is a perspective view of a main part partially shown in cross section, and FIG. 3 is an assembled view of the main part. Here, a case where a differential pressure between pressure P and pressure p is detected will be exemplified. In these figures, 1 is a container, 2a and 2b are permanent magnets installed outside the container 1 and provide magnetic flux as shown by the arrow ψ, and 2o is a yoke, which is a permanent magnet 2a.

2b and covers the container 1 from the outside. 21.22
is a partition wall that partitions the inside of this container into two parts. partition wall 21,
Into each room 1a, ib divided by 22, pressure p to be measured is introduced from pressure introduction holes 11.12 1'.
2.

Reference numeral 3 denotes a pressure sensing portion which is a feature of the present invention, and is composed of a fixed plate 4 fixed to one partition wall 21, 22, and a movable portion 6 disposed opposite to the fixed plate 4 with a spacer 5 in between.

The fixed plate 4 is provided with a plurality of slits (five slits in this case) 41 that guide the pressure in the room 1b.

The movable part 6 includes a frame 61 and a movable plate 62 supported by the frame 61 via a support part 63 and installed to face the fixed plate 4. slits (here, five slits) 64 are provided in positions of the fixed plate 4 that do not face the plurality of slits 41 . Here, the support part 63 that supports the movable plate 62 also functions as a spring,
The center of gravity P(
This movable plate 62 is located at two points on the straight line l□ passing through
is supported.

In addition, in this example, the movable plate 62 has two supporting parts 63.
The slit hole 64 is provided only on the left side with respect to the straight line l□ (corresponding to the rotation axis) connecting the two.

71 is an electrode plate provided on the fixed plate 4, 72 is a 'rlL electrode plate 7
1, which are provided on the movable plate 62, and constitute a displacement detecting means t for the movable plate 62. A coil 8 is formed on the peripheral edge of the movable plate 62 and applies a force to the movable plate 62 according to the current flowing therein.

The operation of the apparatus configured in this way will be explained next.

A state in which no pressure is introduced into the pressure introduction holes 11 and 12 (room 1
In a state in which the pressures in a and 1b are equal), the OF moving plate 62 is held with a slight distance d between it and the fixed plate 4, which is equal to the thickness of the spacer 5. As the spacer 5, a plating layer provided on the fixed plate 4 may be used to obtain a small distance.The pressure P is introduced from the pressure introduction hole 11, and the pressure p2 is introduced from the pressure conductor hole 12. If (p□〈P
2), the pressure p2 in the chamber 1b is determined by passing through the plurality of slit holes 41fI provided in the fixed plate 4 as shown by the arrows.
It is applied to the back surface of one side of the movable plate 62 that does not have a slit hole. Moreover, the pressure P□ in the chamber 1a is applied to the entire surface of the movable plate 62, and also passes through the slit hole 64 of the movable plate 62 to the back surface of one side where the slit hole 64 of the movable plate 62 is provided. . FIG. 4 shows the movable plate 62 in this state.
It shows the state of pressure applied to.

Therefore, in the movable plate 62, on one side where the slit hole 64 is provided, the pressure between the front side and the back side through the slit hole 64 is p□, and no sit torque occurs.

On the other hand, on the other side where the slit hole 64 is not provided, pressures P and P are applied to the front side and the back side, respectively, so a torque proportional to the difference between P and P is movable. occurs on plate 62. As a result, the movable plate 62 is
It is tilted by an angle corresponding to the difference between □ and P2.

Here, the movable plate 62 is provided with a slit hole 64, and the movable plate 62 and the frame 61 are separated, so that the fluid (gas or liquid) in the chambers 1a and 1b is Although it leaks through these, it can be prevented by reducing the size of the slit hole 41, the slot hole 64, the gap width d1 between the movable plate 62 and the frame 61, and the distance d between the fixed plate 4 and the movable plate 6. Since the fluid resistance at each part is large, the movable plate 62 can be tilted in accordance with the pressure difference.

The displacement (inclination angle change) of the movable plate 62 is caused by the electrode plates 71 and 72.
This results in a change in the capacitance t Cx between.

FIG. 5 is a block diagram showing an example of an electric circuit connected to the electrodes 71 and 72.

The capacitance tCx between the electrodes 71 and 72 is detected by a capacitance measuring circuit 73, which outputs a voltage e corresponding to Cx.

The adder circuit 74 calculates the difference between the voltage signal e from the capacitance measuring circuit 73 and the voltage signal e8 corresponding to the initial capacitance Co (state where pressure P□, P2 is zero), and calculates the difference a(me-
e) is applied to the amplifier 75. The amplifier 75 amplifies the deviation X difference 6 and gives the output to the coil 8 provided on the movable plate 62, and measures the voltage (voltage across the resistor 76) corresponding to the current flowing through the coil 8 with a meter 77. I am asking you to do so.

The amplification degree of the amplifier 75 is sufficiently large, and the torque generated in the movable plate 62 by the current flowing through the coil 8 is opposite to the direction of the torque generated by the pressure difference between the pressures p□ and P2 (
Thus, the movable plate 62 is force-balanced so that the input voltage ε of the amplifier 75 becomes zero.

In the force equilibrium state, the movable plate 62 is balanced at the point where the electrode interrogation NOx is equal to the initial capacity C0, and the reading on the meter 77 is given by the differential pressure between the pressures P and P. It is possible to know the pressure difference between pl and p2 from this indicated value.In the device configured in this way, the movable plate 62 is responsible for the pressure difference, and the movable plate's torque based on the pressure difference is is known from the amount of feedback, the acceleration (translational motion component) due to gravity and external vibration does not become the force (torque) that rotates the movable plate 62, and the pressure is influenced by vibration noise and posture changes (gravity). It can be measured without being affected. Moreover, pressure measurement can be performed without being affected by the spring constant of the support portion of the movable plate 62, changes thereof, friction, and the like.

FIGS. 6 and 7 are a plan view and a sectional view of main parts showing other examples of the pressure sensing section 5. FIG.

In the embodiment shown in FIG. 6, in the movable plate 62, the rotation axis l
A plurality of slit holes 648L (nine in this case) are formed at a pitch P over the entire surface of the left side 62a with respect to □, and slit holes 64a and slit holes 648L are formed at the upper and lower peripheral edges of the right side 62b. The same number of circular cedar-shaped slit holes 64
b.

According to this embodiment, the left and right lances of the movable plate 62 can be easily taken, and the axis of rotation l
In the embodiment shown in FIG. 7, holes can be formed in the movable plate 62 at symmetrical positions.
In the fixed plate 4, there is a recess 42 on the left side with respect to the rotation axis.
The distance between the i-+J' moving plate and the fixed plate in this part is d2 (d2>d).

In this embodiment, the recess flB 42 of the fixing plate 4 (return pressure is determined by the interval d2 in this vicinity being 11! in the other parts).
Since it is larger than the distance d, the pressure is close to P or P2, and it is possible to generate torsion corresponding to the differential pressure between the movable plate 62 K Pl and P2.

In each of the above embodiments, the displacement or torque of the movable plate 62 is detected as a change in capacitance between the electrodes, but other means, such as using an optical signal or using a nozzle flat ＜Use a mechanism or
Strain or stress in the support portion 63 may also be detected. Further, although the electromagnetic force of a coil provided on the movable plate is used as a means for applying a feedback force to the movable plate 62, other means such as electrostatic force may be used. In this case, magnet 2a,
2b becomes unnecessary.

[Effects of the present invention]

As explained above, according to the present invention, a highly sensitive pressure sensor is provided that is not affected by vibration noise or changes in posture, and is not affected by displacement of the movable plate or changes in the characteristics of the torque detection means. can be realized.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the configuration of an example of the pressure sensor according to the present invention, Fig. 2 is a perspective view of the main part showing a partial cross section, Fig. 3 is an assembled configuration diagram of the main part, and Fig. 4 is a movable plate. An explanatory diagram showing the state of pressure applied to the
2, FIG. 6, and FIG. 7 are a plan view and a sectional view of main parts showing other examples of the pressure sensing section. 1... Container, 2O... Yoke, 2a, 2b...
Magnet, 3... Pressure detection section, 4... Fixing plate, 5...
Spacer, 6... Movable part, 61... Frame, 62
...Movable plate, 63...Support part, 71°72...Electrode plate, 8...Coil. M1 drawing rough 3 drawing 6 claw 4 drawing

Claims (1)

[Claims] (1) A fixing plate with slots and holes through which pressure is introduced;
A movable plate that is arranged opposite to the fixed plate and receives a first pressure on one side and a second pressure introduced through the slit hole of the fixed plate on the other side, passing through the center of gravity of the movable plate. A support part that rotatably supports the movable plate at two points on a straight line, a means for detecting the displacement or torque of the movable plate, and a signal from the detection means is input and a force corresponding to the signal is applied to the movable plate. A pressure sensor characterized in that the pressure sensor is provided with a force feedback means, and the differential pressure between the first pressure and the second pressure is known from a signal given to the force feedback means.