JPH08233671A - Pressure sensor device - Google Patents

Abstract

PURPOSE: To prevent infiltration of a solder ball into the detecting part side, and secure reliability of a sensor over a long period of time by providing a detecting part whose capacitance changes, a reference part whose capacitance does not change, a signal processing means and a filter means. CONSTITUTION: A detecting part 1 composed of a fixed electrode and a movable electrode has capacitance c1 of a capacitor 1a composed of one fixed electrode and a movable electrode and capacitance c2 of a capacitor 1b composed of a movable electrode. A reference part 2 has capacitance CR being a reference of a capacitor 2. CR oscillating circuits 31, 32 and 33 and a frequency measuring circuit 3X which are connected to the reference part 2 and are composed of the capacitance c1, c2 and CR and a resistance and respectively output signals of oscillating frequencies f1, f2 and fr, are provided inside a gate array 3. A pulse output circuit 4 performs signal processing such as amplification oo a pulse signal outputted from the gate array 3. A filter means prevents a solder ball generated at soldering time from infiltrating into the detecting part 1 and a pressure receiving part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor device which detects the pressure of a fluid (gas or the like) and outputs a signal corresponding to the pressure.

[0002]

2. Description of the Related Art As a conventional pressure sensor device of this type, there is a technique disclosed in Japanese Patent Laid-Open No. 59-171826. This disclosed technology attempts to compensate the temperature by matching the temperature coefficients of the housing, the diaphragm, and the spacer. The diaphragm supporting the movable electrode by soldering is fixed to the housing made of a metal material by soldering. The annular spacer made of a plastic material is fixed to the housing with screws, and the iron plate as a fixed electrode is fixed with screws so as to face the movable electrode.

[0003]

However, in the case of the technique disclosed in JP-A-59-171826, since the movable electrode is soldered to the diaphragm, the material of the diaphragm is limited, Is limited. In addition, special equipment for soldering is required for production, resulting in poor mass productivity. In terms of performance, since the sensor is composed of a pair of movable and fixed electrodes, deterioration of the sensor linearity due to parasitic capacitance is unavoidable. It is necessary and cannot be used for applications that require a system. In addition, there is a problem that it cannot be used for industrial purposes because the humidity cannot be corrected.

Further, the solder ball enters between the fixed electrode and the movable electrode, short-circuits the fixed electrode and the movable electrode respectively, and becomes inoperable, and the solder ball enters the diaphragm side, There is a problem that the diaphragm stops working and becomes inoperable.

The present invention has been made by paying attention to the above-mentioned problems, and its purpose is to make it possible to correct the absolute value of the characteristic by circuit processing and to perform complicated correction such as origin correction during use. (EN) Provided is a pressure sensor device, which not only does not require processing but also prevents solder balls generated during soldering from entering the detection portion side and can secure the reliability of the sensor for a long period of time. It is in.

[0006]

In order to achieve the above object, a pressure sensor device according to the present invention comprises a detection unit in which electrostatic capacitances C1 and C2 change according to a predetermined action from the outside, and A reference unit in which the capacitance CR does not change due to a predetermined action, and a signal processing unit which processes the capacitances C1 and C2 detected by the detection unit and the capacitance CR detected by the reference unit and outputs a desired signal. And a filter means for preventing a solder ball generated at the time of soldering from entering the detection portion and the reference portion.

In order to achieve the above object, the pressure sensor device according to the present invention detects a pressure receiving portion using a diaphragm as a pressure receiving member for detecting the pressure of a pressure fluid, and a reference capacitance CR. And a fixed electrode on one side and the other fixed electrode, and a movable electrode located between these fixed electrodes and moving according to the pressure sensed by the pressure receiving unit. A detection unit that detects the capacitance C1 and the capacitance C2 between the other fixed electrode and the movable electrode, and the capacitances C1 and C2 detected by the detection unit and the reference capacitance detected by the reference unit. A signal processing means for processing the capacitance CR and outputting a desired signal; and a filter means for preventing at least the solder ball generated during soldering from entering the detection portion and the pressure receiving portion. To do.

Further, it is preferable that the filter means is a filter having air permeability. Further, it is preferable that the filter means has a structure in which a large number of fine holes are formed in the fixed electrode so as to have a filter function.

[0009]

In the pressure sensor device according to the present invention, the assembling property is excellent, and since the reference portion is built in and the absolute value of the characteristic can be corrected by the circuit processing, it is possible to correct the origin during use. No complicated processing is required, and the sensor linearity is
Not only is it less susceptible to temperature and humidity, but the number of parts is small, and the productivity is improved at low cost.

In particular, solder balls generated during soldering tend to enter the detection portion side through through holes or the like, but the presence of the filter means prevents the solder balls from entering.

Further, the solder ball is prevented from penetrating between the fixed electrode and the movable electrode and short-circuiting the fixed electrode and the movable electrode to make them inoperable. Further, the solder ball is prevented from becoming inoperable. It will not enter the side and stop the movement of this diaphragm to make it inoperable.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional view of a pressure sensor device according to a first embodiment of the present invention, FIG. 2 is a perspective view of the pressure sensor device in an exploded state, FIG. 3 is a plan view of a diaphragm, and FIG. 4 is a partial sectional view of the diaphragm. FIG. 5 is a sectional view in which a part of the diaphragm is omitted.

The pressure sensor device according to the present invention comprises a base 21, an O-ring 22, a diaphragm 23, a diaphragm retainer 24, an electrode holder 47, and an electric field shield 7.
6, a detection unit (differential sensor unit) 1, and an electric field shield 7
7, the filter 10, the presser spring 78, and the electrode presser 49
And a signal processing unit C and a cover 69.

The base 21 has an accommodating portion 25 having a circular shape in a plan view, and a bottom portion 25a of the accommodating portion 25 has a plurality of concentric stopper portions (negative ends) centered on the center of the bottom portion 25a. Pressure stopper) 26a, 26b, 26c
And an O-ring fitting groove 27 which is located outside the stopper portion 26c and is concentric with the stopper portion 26c. In addition, a concave portion 28 is formed in the bottom surface portion 25a in the radial direction from the center thereof.
The recessed portion 28 communicates with the connecting pipe portion 29 formed on the peripheral surface portion of the base 21 so as to project therefrom, and these constitute the inflow port 40.

The diaphragm 23 is made of metal and has a plate-like shape having a mounting portion 23b on the peripheral portion of the surface portion 23a as shown in FIGS. 3 to 5, and the plunger receiving portion 4 is provided at the center thereof.
1 is formed on the surface portion 23a of the diaphragm 23, and the projecting portions 42a, 42b, 42 projecting downward (in FIG. 5) in an annular shape centered on the plunger receiving portion 41.
c and 42d, and a protruding portion 43 that is located outside the protruding portion 42d and is convex upward are formed, and the upper surface side of the surface portion 23a is a flat surface excluding the protruding portion 43.

The diaphragm retainer 24 has a circular shape in a plan view so as to be inserted into the circular accommodating portion 25 of the base 21, and has a stopper portion (positive pressure stopper) 44 having a flat outer bottom surface. A plunger holding hole 45 is formed in the center of the stopper 44.

The O-ring 22 is fitted in the O-ring fitting groove 27 of the accommodating portion 25 of the base 21, and the diaphragm 23 and the diaphragm retainer 24 are accommodated therein. Holds down the mounting portion 23b at the peripheral portion of the diaphragm 23 to fix the diaphragm 23, and the diaphragm 23 is
It is located in a diaphragm chamber 46 defined by the bottom surface portion 25a of the housing portion 25 and the stopper portion 44 of the diaphragm retainer 24, and the pressure receiving side of the diaphragm chamber 46 communicates with the inflow port 40. Then, the diaphragm retainer 2
Numeral 4 movably holds a plunger 51, which is a movable body, in the plunger holding hole portion 45, and these constitute a pressure receiving unit A.

A hole 50 is formed in the center of the electrode holder 47.
, A receiving portion 52 is formed on the bottom of the electrode holder 47, and a plurality of terminal insertion grooves 53 are formed on the inner peripheral surface of the electrode holder 47. The electric field shield 76 is composed of a disk-shaped shield plate 79 and an annular insulating film 80.

Further, the detection unit 1 includes one fixed electrode 55 having a disk shape, one insulating film 56 having a ring shape, a movable electrode 57 having a disk shape, the other insulating film 58 having a ring shape, and the other insulating film 58 having a disk shape. The fixed electrode 5 is provided with the fixed electrode 59.
5, 59 and the movable electrode 57 have terminal portions 55, respectively.
a, 59a, 57a are formed. One fixed electrode 5
5, a hole 55b is formed in the center of the movable electrode 57, and the movable electrode 57 has a pressing portion 57b at its peripheral portion and a movable portion 57c at its central portion. A plurality of slits 57d are formed in the circumferential direction, and the movable portion 57d is formed by the supporting portions 57e between the slits 57d.
c is retained.

The electric field shield 77 comprises a disk-shaped shield plate 83 and an annular insulating film 84. Further, the electrode retainer 49 has a retainer portion 65 at a lower portion thereof and a signal processing unit accommodating portion 66 at an upper portion thereof.
A plurality of terminal holes 67 are formed in the peripheral portion of the signal processing unit accommodating portion 66. The filter 10 is a disc made of mesh and has air permeability.

In the electrode holder 47, a shield plate 79 of the electric field shield 76 and an annular insulating film 80 are provided, and one fixed electrode 55 and one insulating film 56 of the detecting section 1 are provided. The movable electrode 57, the other insulating film 58, and the other fixed electrode 59 are housed in this order in a stacked manner, and the movable electrode 57 has its holding portion 57b sandwiched by the insulating films 58 and 56 from above and below. The terminal portions 55 a, 59 a, 57 a are inserted into the terminal insertion groove 53 on the inner peripheral surface portion of the electrode holder 47.

In the electrode holder 47, the shield plate 83 of the electric field shield 77, the insulating film 84, the filter 10, and the pressing spring 78 are housed so as to overlap with the detection unit 1. Further, in the electrode holder 47, the pressing portion 65 of the electrode pressing member 49 is inserted so as to overlap the detection unit 1 and the electric field shield 77, and the signal processing unit accommodating portion is inserted from the terminal hole 67 of the electrode pressing member 49. 66
The terminal portions 55a, 59a, 57a are projected toward.

The portion extending from the electrode holder 47 to the electrode retainer 49 constitutes a sensor unit B, which is the accommodating portion 2 of the base 21.
5 and one end (lower end) of the plunger 51 has a plunger receiving portion 41 of the diaphragm 23.
And the other end (upper end) of the plunger 51 is in contact with the movable portion 57c of the movable electrode 57 from below.

The signal processing unit C has a substrate 68 having a shape that can be fitted in the signal processing unit accommodating portion 66. The substrate 68 has the reference portion 2 and the capacitance detection circuit shown in FIG. The gate array 3 and the pulse output circuit 4 are incorporated. The reference unit (reference unit) 2 is
The capacitor 2a is composed of an element having a capacitance CR that serves as a reference.

The signal processing unit C is accommodated in the signal processing unit accommodating portion 66 of the electrode retainer 49, and the terminal portions 55a, 59a and 57a are soldered to the corresponding connecting portions of the substrate 68. It is connected. A cover 69 is covered over the electrode retainer 49, and the cover 69 includes the guide pin 90 and the press-fitting pin 91.
Pin hole 86 provided in the base 21 and pin press-fitting hole 8
Lead wires 71, 7 fixed to the base 21 by being inserted and press-fitted into the base plate 7 and connected to the substrate 68.
2, 73 are led out of the cover 69. in this case,
The lead wires 71, 72, 73 are the electrode retainer 49 and the cover 69.
It is sandwiched between the protrusions 74 and 75 provided on the
The lead wires 71, 72, 73 have a large drawing strength. The lead wires 71, 72, 73 are connected to the board 68 by soldering.

In the sensor unit B, the detection unit 1 composed of the two fixed electrodes 55 and 59 and the movable electrode 57 has a capacitance C1 of the capacitor 1a composed of one fixed electrode 55 and the movable electrode 57. And the other fixed electrode 5
9 and the electrostatic capacitance C2 of the capacitor 1b constituted by the movable electrode 57. Further, the reference unit 2 has a capacitance CR that serves as a reference for the capacitor 2a.

The inside of the gate array 3 is roughly connected to the detection unit 1 and the reference unit 2 and has a capacitance C.
Oscillation frequency f determined by 1, C2, CR and resistor not shown
There are CR oscillating circuits 31, 32, and 33 that output the signals 1, f2, and fr, respectively, and, in response to these signals, in the first half of one cycle of the reference oscillating signal fr from the CR oscillating circuit 33, the first half Oscillation frequency f1 in cycle, latter half 1 /
There is a frequency measurement circuit 3X that generates a pulse signal according to the frequency difference of f2 in two cycles. The pulse output circuit 4 amplifies the pulse signal output from the gate array 3,
Perform signal processing such as level adjustment.

Next, the operation of the pressure sensor device constructed as described above will be described. The diaphragm chamber 46
When the pressure on the pressure receiving side is zero, the movable electrode 57 in the detection unit 1 is not displaced, so that the electrostatic capacitances C1 and C2 are equal. Therefore, the oscillation frequencies f1 and f
2 becomes equal, and the oscillation frequency f1 in the first half cycle of the reference oscillation signal fr from the CR oscillation circuit 33 and the latter half 1 /
Since the frequency difference between the oscillation frequencies f2 in the two cycles is zero, no pulse signal is output from the gate array 3.

When a pressure fluid (eg, gas) is introduced from the inlet 40 to the pressure receiving side of the diaphragm chamber 46, the diaphragm 23 is displaced upward in FIG. Due to the upward displacement of the diaphragm 23, the movable portion 57c of the movable electrode 57 is pushed through the plunger 51 and displaced upward in FIG. 1, and the electrostatic capacitances C1 and C2 have different values. Therefore, since there is a frequency difference between the oscillation frequency f1 in the first half cycle and the oscillation frequency f2 in the second half cycle of the reference oscillation signal fr from the CR oscillation circuit 33, the frequency difference is generated from the gate array 3. That is, a number of pulse signals proportional to the pressure to be detected is output.

By the way, the capacitances C1 and C2 change depending on the surrounding environment, that is, the temperature, the material composition of the pressure fluid for measuring the pressure, and the like. Therefore, the CR oscillation circuit 31
Although the oscillation frequencies f1 and f2 at 32 and 32 also change, the capacitance CR of the reference unit 2 also changes at the same time, so that a measurement error due to a change in the surrounding environment can be eliminated without providing a correction circuit or the like. it can.

In the pressure sensor device described above, the sensor unit B, which constitutes the portion from the electrode holder 47 to the electrode holder 49, is housed in the housing portion 25 of the base 21, and the signal processing unit C is held in the electrode holder. The signal processing unit accommodating portion 66 of 49, the terminal portion 55
The terminal portions 55a, 59a, 57a are soldered to the corresponding patterns of the substrate 68 by penetrating the through holes 68a of the substrate 68 with a, 59a, 57a. Although the ball tries to enter the sensor unit B side through the through hole 68a or the like, the shield plate 8 of the electric field shield 77 is used.
Since the filter 10 is interposed between 3 and the pressing spring 78, the filter 10 prevents the solder ball from entering the fixed electrode 59 side. Also, when soldering the lead wires 71, 72, 73 to the substrate 68, solder balls are generated, but the filter 10 prevents the solder balls from entering the fixed electrode 59 side.

Therefore, the solder ball penetrates between the fixed electrode 59 and the movable electrode 57 or between the movable electrode 57 and the fixed electrode 55 to connect the fixed electrode 59 and the movable electrode 57, and the movable electrode 57 and the fixed electrode 55. It is prevented that the solder balls are short-circuited and become inoperable, and the solder balls do not enter between the diaphragm 24 and the diaphragm retainer 24 to stop the movement of the diaphragm 24 and become inoperable. .

The filter 10 is not limited to the disc-shaped one made of the mesh described above, but may be a normal ventilation filter. Further, as shown in FIG. 7, it is possible to omit the filter 10 by forming a large number of fine holes 59b in the fixed electrode 59 so as to have a filter function.

[0034]

As described above, in the pressure sensor device according to the present invention, the electrostatic capacitances C1 and C2 change according to a predetermined action from the outside, and the electrostatic sensor is used depending on the predetermined action. A reference unit in which the capacitance CR does not change; signal processing means for processing the capacitances C1 and C2 detected by the detection unit and the capacitance CR detected by the reference unit and outputting a desired signal;
Solder balls generated at the time of soldering and having a filter means for preventing intrusion to the detection portion and the reference portion, excellent in assemblability, and the built-in reference portion,
Since the absolute value of the characteristic can be corrected by circuit processing, complicated processing such as origin correction during use is unnecessary, and the sensor linearity is not easily affected by temperature and humidity, and the number of parts is small and the cost is low. Will improve productivity.

In particular, the solder balls generated at the time of soldering try to enter the detecting portion side through the through holes or the like, but the presence of the filter means prevents the solder balls from entering. Therefore, the reliability of the sensor can be ensured for a long period of time.

Further, the pressure sensor device according to the present invention is
A pressure receiving portion using a diaphragm as a pressure receiving member for detecting the pressure of the pressure fluid, a reference portion for detecting a reference electrostatic capacitance CR, one and the other fixed electrodes, and the pressure receiving portion located between these fixed electrodes. The unit has a movable electrode that moves according to the sensed pressure, and detects a capacitance C1 between one fixed electrode and the movable electrode and a capacitance C2 between the other fixed electrode and the movable electrode. A detection unit, and signal processing means for processing the electrostatic capacitances C1 and C2 detected by the detection unit and the reference electrostatic capacitance CR detected by the reference unit and outputting a desired signal,
Since the solder ball generated at the time of soldering is provided with at least the detecting portion and the filter means for preventing the solder ball from entering the pressure receiving portion, the solder ball enters between the fixed electrode and the movable electrode. Therefore, the fixed electrode and the movable electrode are not short-circuited to be inoperable, and the solder ball is prevented from entering the diaphragm side and stopping the movement of the diaphragm to become inoperable. Therefore, the reliability of the sensor can be ensured for a long period of time.

Further, since the filter means is a breathable filter, it is easy to assemble, and the filter means is provided with a plurality of fine holes in the fixed electrode so as to have a filter function. In the case of such a configuration, a separate filter can be omitted.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a pressure sensor device according to the present invention.

FIG. 2 is a perspective view of the pressure sensor device in an exploded state.

FIG. 3 is a plan view of a diaphragm.

FIG. 4 is a partial cross-sectional side view of the diaphragm.

FIG. 5 is a cross-sectional view of the diaphragm with a part thereof omitted.

FIG. 6 is a schematic block diagram of a capacitance detection circuit of the pressure sensor device according to the present invention.

FIG. 7 is a perspective view of a fixed electrode having a filter function.

[Explanation of symbols]

 1 Detection Section 2 Reference Section 10 Filter (Filter Means) 23 Diaphragm 55 One Fixed Electrode 57 Movable Electrode 59 Other Fixed Electrode C Signal Processing Means

Claims (4)

[Claims] 1. A detection unit in which electrostatic capacitances C1 and C2 change in response to a predetermined external action, a reference unit in which electrostatic capacitance CR does not change due to the predetermined action, and a static electricity detected by the detection unit. Signal processing means for processing the capacitances C1 and C2 and the electrostatic capacitance CR detected by the reference portion and outputting a desired signal, and preventing solder balls generated during soldering from entering the detection portion and the reference portion. And a filter means for controlling the pressure sensor device. 2. A pressure receiving portion using a diaphragm as a pressure receiving member for detecting the pressure of a pressure fluid, a reference portion for detecting a reference electrostatic capacitance CR, and one and the other fixed electrodes and these fixed electrodes. A movable electrode that is positioned and moves according to the pressure sensed by the pressure receiving portion, and has a capacitance C between one fixed electrode and the movable electrode.
Capacitance C2 between one and the other fixed electrode and the movable electrode
And a signal processing unit that processes the electrostatic capacitances C1 and C2 detected by the detecting unit and the reference electrostatic capacitance CR detected by the reference unit and outputs a desired signal, and when soldering 1. A pressure sensor device comprising: at least the detecting portion and a filter means for preventing the solder ball generated in the inside from entering the pressure receiving portion. 3. The pressure sensor device according to claim 1, wherein the filter means is a filter having air permeability. 4. The pressure sensor device according to claim 1 or 2, wherein the filter means has a structure in which a large number of fine holes are formed in the fixed electrode to provide a filter function.