JPH08136377A - Pressure sensor and pressure sensor unit - Google Patents

Abstract

PURPOSE: To prevent the invasion of foreign articles such as fine particles, dust, etc., into a pressure chamber of a pressure sensor. CONSTITUTION: A glass cover 2 is attached to the upper surface of a silicon frame 1 having a diaphragm 3 integrally supported therewith, thereby forming a pressure chamber 4 between the frame 1 and diaphragm 3. Trapping electrodes 8a, 8b are formed at the inner surfaces of the frame 1 and the cover 2 to face a pressure introduction path 7 communicating with the pressure chamber 4 from a side face of a pressure sensor A. A dust collection capacitor is thus formed. Fine dust particles in the air are collected by the static attraction force of the trapping capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor and a pressure sensor unit. More specifically, the present invention relates to a method of preventing foreign matter from entering a pressure introducing portion provided in a pressure sensor in a differential pressure type pressure sensor or a pressure sensor unit accommodating the differential pressure type pressure sensor.

[0002]

2. Description of the Related Art A semiconductor pressure sensor is extremely small in size, has excellent sensitivity, and is resistant to temperature changes in the surrounding environment. Therefore, research and development have been actively conducted in recent years. The pressure sensor N is shown in FIG.
The schematic sectional drawing of is shown. The pressure sensor N is the frame 101.
A thin film-shaped diaphragm 103 is supported substantially at the center, and the frame 101 and the diaphragm 103 are integrally formed from a silicon wafer or the like. Frame 1
A cover 102 made of glass or the like is joined to the upper surface of 01, a pressure chamber 104 is provided between the diaphragm 103 and the cover 102, and the diaphragm 103 can be elastically displaced in the thickness direction. There is.

A pressure introducing passage 107 is provided from the side surface of the pressure sensor N to the pressure chamber 104.
4 The inside is open to the atmosphere. Then, when the pressure of the fluid such as gas or liquid is introduced toward the lower surface of the diaphragm 103, the pressure depending on the magnitude of the introduced pressure [the pressure difference in the pressure chamber 104 (atmospheric pressure)]. The diaphragm 103 is displaced. When the diaphragm 103 is displaced, the distance between the diaphragm 103 and the cover 102 changes, and the movable electrode 10 formed on the upper surface of the diaphragm 103 is changed.
5 and the fixed electrode 106 on the inner surface of the cover 102 change in capacitance. Therefore, the magnitude of the introduced pressure (differential pressure from the atmospheric pressure) can be known by detecting the change in the magnitude of the electrostatic capacitance.

[0004]

However, in such a pressure sensor, when used for a long period of time due to its structure, foreign matter such as dust and dirt in the atmosphere may enter the pressure chamber through the pressure introducing passage. was there. In such a case, there is a problem in that the foreign matter that has entered is clogged in the pressure chamber to hinder the displacement of the diaphragm, causing a malfunction such as a decrease in sensor sensitivity.

Further, this pressure sensor is usually incorporated in a pressure measuring device such as a gas meter or a blood pressure monitor as a post-pressure sensor unit which is housed in a package made of metal or plastic. However, even if the pressure sensor unit is housed in the pressure sensor unit, dust or the like may enter the pressure chamber through the pressure introduction path provided in the package during storage. Therefore, in storing the pressure sensor unit, it is necessary to store the pressure sensor unit in a place such as a clean room where there is no foreign matter such as dust and dirt, and the storage facility and storage method are costly.

The present invention has been made in view of the above-mentioned drawbacks of conventional examples, and an object thereof is to prevent foreign matter such as dust and dirt from entering the pressure chamber of the pressure sensor. To prevent the malfunction of.

[0007]

A first pressure sensor according to the present invention comprises a fixed substrate bonded to at least one surface of a support substrate which supports a diaphragm whose flexure amount changes due to pressure change, and fixed to the diaphragm. A pressure sensor for detecting a pressure difference between a pressure of a first pressure introducing portion provided between the diaphragm and a substrate and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, It is characterized in that a pressure introducing passage for introducing pressure to the first or second pressure introducing portion is provided, and foreign matter intrusion preventing means is provided in a part or the whole of the pressure introducing passage.

As the foreign matter invasion preventing means, for example, a dust collecting capacitor can be provided in a part or the whole of the pressure introducing passage for introducing pressure into the first pressure introducing portion. It is preferable to always apply a voltage to the dust collecting capacitor,
It can also be shared at least in part with an auxiliary capacitor such as a temperature compensating capacitor.

Further, as a foreign matter intrusion preventing means, a narrow path having a gap smaller than the gap between the diaphragm and the fixed substrate may be provided in a part of the pressure introducing path for introducing the pressure into the first pressure introducing section. .

Further, a plurality of grooves or holes having a width smaller than the gap between the diaphragm and the fixed substrate may be provided in a part of the pressure introducing passage for introducing pressure to the first pressure introducing portion.

In the second pressure sensor of the present invention, a fixed substrate is bonded to at least one surface of a support substrate that supports the diaphragm, the amount of bending of which changes according to the pressure change, and the fixed substrate is provided between the diaphragm and the fixed substrate. In the pressure sensor for detecting the differential pressure between the pressure of the first pressure introducing portion and the pressure of the second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, the first or second pressure sensor is provided. The pressure introducing section for introducing the atmospheric pressure is provided in the pressure introducing section, and the open end of the pressure introducing path is arranged vertically downward.

In the first pressure sensor unit of the present invention, the fixed substrate is bonded to at least one surface of the support substrate supporting the diaphragm whose flexure amount changes by the pressure change, and the fixed substrate is bonded between the diaphragm and the fixed substrate. A pressure sensor for detecting a pressure difference between a pressure of a first pressure introducing portion provided and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, and the pressure sensor are housed. A pressure sensor unit comprising a sensor package and having a pressure introducing path for introducing pressure to the first or second pressure introducing section in the sensor package, for preventing foreign matter from entering a part or the whole of the pressure introducing path. It is characterized by the provision of means.

As a foreign matter invasion preventing means, a dust collecting capacitor or a dust removing filter can be provided in the pressure introducing passage, the pressure introducing passage is sealed with a liquid, and the first pressure sensor is provided through the liquid. Alternatively, the pressure may be introduced into the second pressure introducing section.

In the second pressure sensor unit of the present invention, the fixed substrate is bonded to at least one surface of the support substrate that supports the diaphragm whose deflection amount changes according to the pressure change, and the fixed substrate is bonded between the diaphragm and the fixed substrate. A pressure sensor for detecting a pressure difference between a pressure of a first pressure introducing portion provided and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, and the pressure sensor are housed. In a pressure sensor unit comprising a sensor package and having a pressure introducing passage for introducing atmospheric pressure into the first or second pressure introducing portion, the open end of the pressure introducing passage is directed vertically downward. It is characterized by having been placed.

In the third pressure sensor unit of the present invention, a fixed substrate is bonded to at least one surface of a support substrate that supports a diaphragm whose bending amount changes due to pressure change, and the fixed substrate is connected to the diaphragm. A pressure sensor for detecting a differential pressure between a pressure of a first pressure introducing portion provided between the pressure sensor and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion; In a pressure sensor unit having a pressure introducing passage for introducing pressure into the first or second pressure introducing portion, the end portion of the pressure introducing passage is sealed with a seal. It is characterized by blocking by sticking.

The gas meter of the present invention is a gas meter having a function of detecting a decrease in gas pressure, and is the first or second pressure sensor of the present invention or the first or second pressure sensor of the present invention.
It is characterized in that it is provided with a second or third pressure sensor unit.

The sphygmomanometer of the present invention is a sphygmomanometer for measuring blood pressure with a pressure sensor via blood pressure detecting means such as a cuff body, and is the first or second pressure sensor of the present invention or the above-mentioned present invention. It is characterized in that it is provided with a first, second or third pressure sensor unit.

[0018]

In the first pressure sensor of the present invention, it is possible to prevent foreign matter such as dust and dirt from entering the pressure introducing passage from entering the pressure introducing portion. In particular, it is possible to prevent foreign matter or the like from entering the first pressure introducing portion between the diaphragm and the fixed substrate and clogging the first pressure introducing portion to prevent displacement of the diaphragm.

Specifically, if a dust collecting capacitor is provided in a part or the whole of the pressure introducing passage for introducing pressure to the first pressure introducing portion and a voltage is constantly applied, the dust will not enter. It is possible to continuously collect dust and other foreign matter by static electricity.

At this time, if the dust collecting capacitor shares at least a part with an auxiliary capacitor such as a temperature compensating capacitor, the structure of the pressure sensor provided with the auxiliary capacitor can be simplified and the number of manufacturing steps can be reduced. A highly accurate pressure sensor can be manufactured.

Further, a narrow passage having a gap smaller than the gap between the diaphragm and the fixed substrate is provided in a part of the pressure introducing passage for introducing the pressure to the first pressure introducing portion so as to prevent the displacement of the diaphragm. It is possible to prevent foreign matter such as dust of various sizes from entering the first pressure introducing portion by stopping the foreign matter in a narrow path.

Further, by providing a plurality of grooves or holes having a width smaller than the gap between the diaphragm and the fixed substrate in a part of the pressure introducing passage for introducing pressure to the first pressure introducing portion, the diaphragm It is possible to prevent foreign matter such as dust having a size that hinders the displacement from entering the first pressure introducing portion by stopping at the groove portion or the hole portion. Moreover, since a plurality of grooves and holes are provided, the fluid resistance of the pressure introducing passage can be reduced, and the pressure detection accuracy is not reduced.

In the second pressure sensor of the present invention, the open end of the pressure introducing passage for introducing atmospheric pressure into the pressure introducing portion is directed vertically downward so that foreign matters such as dust and dust in the atmosphere are naturally generated. It is possible to prevent the pressure from penetrating into the pressure introducing portion. In particular, it is possible to prevent foreign matter in the atmosphere from entering through the open pressure introducing passage and clogging the first pressure introducing portion between the diaphragm and the fixed substrate to prevent displacement of the diaphragm.

In the first pressure sensor unit of the present invention, since the foreign substance invasion preventing means is provided in the pressure introducing passage for introducing pressure to the pressure introducing portion of the pressure sensor, dust from the pressure introducing passage of the sensor package. It is possible to prevent foreign matter such as dust and dirt from entering the pressure introducing portion. Therefore, it is possible to prevent dust or the like from entering the pressure introducing portion of the pressure sensor, and particularly to prevent clogging between the diaphragm and the fixed substrate to prevent displacement of the diaphragm.

At this time, if a dust collecting capacitor is provided in the pressure introducing passage provided in the sensor package, it is possible to collect dust and the like that enter the pressure introducing portion due to static electricity.

If a dust removing filter is provided in the pressure introducing passage, the dust removing filter can remove dust and the like entering the pressure introducing portion.

Further, if the pressure introducing passage is sealed with a liquid and the pressure is introduced into the pressure introducing portion via the liquid, it is possible to prevent dust and the like from entering the pressure introducing portion.
Further, invasion of gas such as water vapor that deteriorates the pressure sensor is also prevented, and the life of the pressure sensor is extended.

In the second pressure sensor unit according to the present invention, the open end of the pressure introducing passage for introducing the atmospheric pressure to the pressure introducing portion is directed vertically downward so that foreign matters such as dust and dust in the atmosphere are removed. It is possible to prevent natural intrusion into the pressure introducing portion.

Further, in the third pressure sensor unit of the present invention, since the end of the pressure introducing passage is closed by sticking a seal, dust from the pressure introducing passage during transportation or in stock, etc. It is possible to prevent dust and the like from entering the pressure introducing portion.

In the gas meter and blood pressure monitor of the present invention,
Since foreign matter such as dust and dirt does not enter the pressure introducing section,
No malfunction occurs even after long-term use. Also,
Even if it is used in an environment with a lot of dust and dirt, it will not easily break down.

[0031]

1 is a partially cutaway perspective view showing a pressure sensor A according to an embodiment of the present invention. In the pressure sensor A, a thin film-shaped diaphragm 3 is supported substantially in the center of a frame 1, and the frame 1, the diaphragm 3 and the pressure introduction path 7 are integrally manufactured from a silicon wafer or the like by a semiconductor manufacturing process. A cover 2 made of glass is joined to the upper surface of the frame 1, and a pressure chamber 4 is provided between the cover 2 and the diaphragm 3 so that the diaphragm 3 can be elastically displaced in its thickness direction. . A movable electrode 5 is formed on the upper surface of the diaphragm 3 and is electrically connected to an electrode pad 9a on the upper surface of the frame 1. A fixed electrode 6 is formed on the inner surface of the cover 2 with a small gap from the movable electrode 5 and is electrically connected to another electrode pad 9b on the upper surface of the frame 1.

From the side surface of the pressure sensor A, a pressure introducing passage 7 for introducing a reference pressure (such as atmospheric pressure) toward the pressure chamber 4 is provided. The pressure introducing passage 7 is provided with a dust collecting capacitor as a foreign matter invasion preventing means for preventing foreign matter such as dust and dirt from entering the pressure chamber 4.
The dust collecting condenser faces the pressure introducing passage 7 and faces the frame 1
A pair of trapping electrodes 8a, 8 are provided on the inner surface and the inner surface of the cover 2.
b, the two trapping electrodes 8a and 8b are electrically connected to further electrode pads 10a and 10b on the upper surface of the frame 1, respectively.

However, if a constant voltage is constantly applied between the trap electrodes 8a and 8b from the electrode pads 10a and 10b, an electrostatic force is generated between the trap electrodes 8a and 8b.
Acting as an electrostatic filter, foreign matter such as dust, dirt, and water vapor introduced from the pressure introducing passage 7 is trapped by the electrodes 8a, 8a.
trapped in b. As described above, since the pressure introducing passage 7 is provided with the dust collecting condenser, for example, dust and dirt in the atmosphere, which is the reference pressure, are trapped by the dust collecting condenser, and the dust and dirt are stored in the pressure chamber 4. Foreign matter such as the like does not enter, and it is possible to prevent a decrease in the sensitivity of the pressure sensor A and a malfunction.

FIG. 2 is a schematic diagram of a pressure sensor B according to another embodiment of the present invention, in which the pressure introducing passage 7 is shown.
Is formed so as to circulate (almost half a circle) around the diaphragm 3 along the outer periphery of the pressure chamber 4, and trapping electrodes 8a and 8b are provided on the inner surface of the frame 1 facing the pressure introducing passage 7 and the inner surface of the cover 2, respectively. 7 is provided over almost the entire length. A temperature compensation circuit (not shown) is connected to the electrode pads 10a and 10b, and the trapping electrode 8
a and 8b are provided with electrode pads 10a and 1a from the temperature compensation circuit.
A constant voltage is constantly applied via 0b. Also,
The trapping electrodes 8a and 8b are also used as reference electrodes, and the temperature compensating circuit uses the trapping electrode 8a.
The temperature change of the electrostatic capacitance value between a and 8b is detected, and the electrostatic capacitance value between the movable electrode 5 and the fixed electrode 6 is corrected according to the change, and the static capacitance at a constant temperature (reference temperature) is detected. The calculation is performed so that the value of the capacitance is obtained.

In this pressure sensor B, the pressure introducing path 7
Is formed long, so that it is possible to more reliably trap foreign matters and the like between the trapping electrodes 8a and 8b. Also,
Since the trapping electrodes 8a and 8b can also be used as reference electrodes, a dust collecting capacitor and a reference capacitor can be formed at the same time, and the pressure sensor B with good pressure detection accuracy can be easily manufactured. Further, as compared with the case where the dust collecting capacitor and the reference capacitor are separately formed, there is an advantage that the structure of the pressure sensor B is simple and the size can be reduced. Reference numeral 13 denotes a crimp portion for electrically connecting the fixed electrode 6 provided on the inner surface of the cover 2 to the electrode pad 9b on the upper surface of the frame, and 14 for electrically connecting the trapping electrode 8b to the electrode pad 10b on the upper surface of the frame 1. It is the crimping part.

FIG. 3 is a partially cutaway perspective view showing a pressure sensor C provided with another foreign matter intrusion preventing means. The pressure introducing passage 7 is provided with a protrusion 15 over the entire width.
The pressure introduction path 7a at the top of the pressure chamber is a narrow path smaller than the gap distance of the pressure chamber 4. Therefore, foreign matter such as dust and dirt larger than the gap of the pressure chamber 4 cannot pass through the narrow pressure introduction path 7a, and it is possible to prevent the foreign matter from entering the pressure chamber 4. Protrusion 15
Can be integrally formed with the frame 1, the diaphragm 3 and the pressure introducing passage 7 by etching a silicon wafer, and is simpler in manufacturing process than the case where the trapping electrodes 8a and 8b are formed, and foreign matter intrusion is performed. Preventing means can be provided.

Further, FIG. 4 is an enlarged perspective view in which a part of the pressure sensor D provided with another foreign substance intrusion preventing means is cut away, and is provided so as to close the pressure introducing passage 7. A narrow air passage 17 is provided at the top of the protrusion 16.
Are arranged in the width direction. The height or width of the air passage 17 is smaller than the distance between the gaps of the pressure chamber 4, and foreign matter larger than the gap cannot pass through the air passage 17. In the pressure sensor C, if there is not a sufficient gap in the pressure introduction passage 7a which is a narrow passage, resistance may occur when introducing pressure of the atmosphere or the like, and the response speed of the sensor may decrease. If there is
Since a large number of ventilation passages 17 are provided, the resistance generated when the atmosphere is introduced is small, and the pressure can be introduced into the pressure chamber 4 without decreasing the response speed of the sensor. Further, although the ventilation path 17 is shown as having a groove shape, a foreign material can be sufficiently prevented from entering even if the introduction direction is shorter. Since this ventilation path 17 can also be easily formed by the semiconductor manufacturing process, the manufacturing process does not become complicated.

FIG. 5 is a sectional view showing a pressure sensor E which is still another embodiment of the present invention.
The pressure introducing path 7 for introducing pressure to the pressure introducing path 7 is provided so that the opening 18 of the pressure introducing path 7 faces vertically downward, and the pressure sensor E is housed in the package with the opening 18 facing vertically downward. It is incorporated in a pressure measuring device such as a gas meter or a blood pressure monitor as described later. Foreign matter such as dust and dirt floating in the atmosphere naturally falls due to gravity in an environment where the movement (convection) of the atmosphere is small. Therefore, in the case where the pressure chamber 4 is opened to the atmosphere with little convection and atmospheric pressure is introduced into the pressure chamber 4, the opening 1
By providing the pressure introduction path 7 so that 8 is directed vertically downward, it is possible to prevent foreign matter from entering the pressure chamber 4.

As described above, various measures for preventing foreign matter from entering the pressure sensor itself can prevent foreign matter from entering the pressure chamber. In addition, the pressure sensor is often used by being housed in a package made of metal or plastic, and foreign matter can be prevented from entering the pressure chamber by taking measures to prevent foreign matter from entering the pressure introduction path provided in the package. Can be prevented.

FIG. 6 is a sectional view showing a pressure sensor unit F according to the present invention. In the pressure sensor unit F, for example, a conventional pressure sensor 21 having no foreign matter intrusion prevention means is housed in a package 22 made of metal or plastic, and a pressure introduction path 23 of the pressure sensor 21 is opened in the package 22. ing. A pressure-introducing pipe 26 for introducing the measurement pressure is provided from below the package 22 so as to penetrate the bottom surface, and the measurement pressure can be introduced from the lower surface of the diaphragm of the pressure sensor 21. Further, in order to introduce an atmosphere serving as a reference pressure into the package 22 from the outside of the package 22, for example, a tubular pressure introducing passage 24 is provided so as to project inside the package 22 to prevent foreign matter from entering the pressure introducing passage 24. Means are provided. As a foreign matter invasion preventing means, the pressure introducing passage 24
A pair of trapping electrodes 25, 25 provided on the upper and lower inner surfaces of the trapping electrode face each other to form a dust collecting capacitor. By applying a voltage between the trapping electrodes 25, 25, the dust collecting capacitor functions as an electrostatic filter. Therefore, the pressure introduction path 24
Foreign substances such as dust and dirt that try to enter from the inside are trapped by the trapping electrodes 25, 25, so that the foreign substances can be prevented from entering the pressure chamber of the pressure sensor 21. Then, when the atmospheric pressure from which dust and the like have been removed by the trapping electrodes 25, 25 is introduced into the package 22 from the pressure introducing passage 24 and the measurement pressure is introduced from the pressure introducing pipe 26, the reference pressure (atmospheric pressure) ) And the measured pressure, the diaphragm is displaced, and the measured pressure (differential pressure from the reference pressure) can be obtained. Further, by using the pressure sensor of the present invention provided with the foreign matter intrusion prevention means, it is possible to more effectively prevent foreign matter such as dust and dirt from entering the pressure chamber.

Further, as shown in FIG. 6, if a seal 28 is attached to the surface of the package 22 so as to close the opening 27 of the pressure introducing passage 24, foreign matter such as dust or dust is pressed during transportation or storage. The pressure sensor 21 can be stored in a good condition because it cannot enter the inside of the package 22 through the introduction path 24. As a result, it is not necessary to store in a clean place such as in a clean room, and the storage cost can be reduced.
Further, the seal 28 may be peeled off at the start of use, and there is no inconvenience that foreign matter is clogged in the pressure chamber before use and the pressure cannot be measured because the storage condition is bad.

In the pressure sensor unit G shown in FIG. 7, the dust removing filter 34 is used as a foreign matter intrusion preventing means.
It is provided in the pressure introducing passage 33 provided in the package 32. The dust removal filter 34 is provided with the pressure sensor 31.
The foreign matter or the like larger than the gap distance of the pressure chamber 35 can be removed. For example, a hollow fiber dust removing filter 34 is embedded in the pressure introducing passage 33 without any gap. Foreign matter such as dust and dirt in the atmosphere introduced from the pressure introducing passage 33 is removed by the dust removing filter 34, and it is possible to prevent the foreign matter from entering the pressure chamber 35 from the pressure introducing passage 36 of the pressure sensor 31. . Further, the dust removal filter 34 is not limited to a hollow fiber filter, and a membrane filter such as a membrane filter or a HEPA filter may be used.

FIG. 8 is a perspective view showing a pressure sensor unit H which is still another embodiment according to the present invention. A U is provided outside the package 42 in which the pressure sensor 41 is housed.
A pressure introducing path 43 having a tubular shape is provided, and one end of the pressure introducing path 43 is opened inside the package 42. A certain amount of liquid 44 is stored in the U-shaped portion 43a of the pressure introducing passage 43, the pressure introducing passage 43 is sealed by the liquid 44, and the atmospheric pressure outside the package 42 is inside the package 42 via the liquid 44. Reportedly. At this time, it is desirable that the liquid 44 to be used be capable of transmitting pressure without loss, and that the amount of evaporation is small and the solidification temperature is low so that it can be used for a long period of time and used in various environments. Further, when a liquid 44 such as mercury is used, it is possible to prevent gas such as water vapor, which deteriorates the sensor, from entering the package 42, so that it can be used in a bad environment. It is also preferable from the viewpoint. Further, it is preferable that the inner wall of the pressure introducing passage 43 is formed of a material that does not easily wet the liquid 44, for example, the pressure introducing passage 4
3 If the inner wall is treated with a fluororesin or the pressure introduction path 43 is made of fluororesin such as PTFE (trade name Teflon), the liquid 44 moves smoothly in the U-shaped portion 43a, and the package without pressure loss. An external pressure (atmospheric pressure) can be introduced into the inside of 42. Of course, the U-shaped portion 43a may be provided inside the package 42. In the figure, reference numeral 45 denotes a pressure introducing pipe for introducing the measured pressure. The pressure introduced from the pressure introducing pipe 45 is applied to the lower surface of the diaphragm of the pressure sensor 41 and introduced from the pressure introducing passage 43. The pressure difference between the pressure (atmospheric pressure) and the atmospheric pressure introduced from the pressure introducing pipe 45 can be obtained.

Further, in the pressure sensor unit H,
If the liquid 44 is sealed in the pressure introducing passage 43 in advance, it is possible to prevent foreign matter such as dust or dust from entering the package 42 from the pressure introducing passage 43 during transportation or storage.

FIG. 9 is a sectional view of a pressure sensor unit I which is still another embodiment of the present invention. The opening 54 of the pressure introducing portion 53 of the pressure sensor unit I is provided on the bottom surface of the package 52 in which the pressure introducing pipe 55 is arranged so as to face vertically downward. The pressure sensor unit I is generally used in a place where there is little convection of the atmosphere, and in this case, dust and dust floating in the atmosphere naturally fall according to gravity with the passage of time. Therefore, the opening 5 of the pressure introducing portion 53
By providing 4 vertically downward, it is possible to easily prevent dust and dirt from entering the package 52 from the pressure introducing portion 53. At this time, like the pressure sensor E, if the pressure sensor 51 in which the opening 57 of the pressure introduction path 56 is arranged vertically downward is used, the pressure chamber 58 can be more effectively.
It is possible to prevent foreign matter from entering the area.

FIG. 10 shows a gas meter J of the present invention. The gas meter J is provided with a gas cutoff valve 62 and a metering unit (not shown) for measuring the amount of gas (total amount of gas) flowing through the gas main 61, and measures the amount of gas flowing through the gas main 61. Is measured and displayed on the meter section 63. The pressure sensor 6 is provided on the branch pipe 64 branched from the gas main pipe 61.
5 is connected, and the gas pressure introduced from the branch pipe 64 is applied to the lower surface of the diaphragm of the pressure sensor 65 without leakage. The pressure chamber of the pressure sensor 65 is open to the atmosphere, and foreign matter invasion preventing means 66 is provided in the pressure introduction path of the pressure sensor 61. As the foreign matter invasion preventing means 66, a dust collecting capacitor composed of a pair of electrodes facing each other provided in the pressure introducing path, a hollow fiber-like or film-like dust removing filter, or the like can be used. For example, the first embodiment described above can be used. A pressure sensor A provided with such a dust collecting capacitor can be used. The sensor signal from the pressure sensor 65 is output to the control unit 67, and the control unit 67 constantly detects the gas pressure flowing through the gas main pipe 61. Then
In the unlikely event of a gas leak, the gas pressure flowing through the gas main pipe 61 decreases. The control unit 67 detects the decrease in gas pressure and closes the gas cutoff valve 62 to stop the gas supply or issue an alarm.

Since the foreign matter invasion preventing means 66 is provided in the pressure introducing path of the pressure sensor 65, the pressure sensor 65 does not operate due to foreign matter such as dust or dust,
It is possible to provide a more reliable gas meter J without fear of deterioration of sensitivity and to use gas more safely.

FIG. 11 shows another gas meter K according to the present invention. The gas meter K is provided with an external pressure introducing passage 72 for introducing atmospheric pressure into the pressure chamber of the pressure sensor 71 outside the sensor. The external pressure introducing passage 72 is connected to the pressure introducing passage of the pressure sensor 71. The external pressure introducing passage 72 is provided with foreign matter invasion preventing means 73 such as a dust collecting condenser formed of a pair of electrodes facing each other, a hollow fiber-like or film-like dust removing filter, and the like. Alternatively, the liquid may be sealed in the U-shaped external introduction path 72, and the atmospheric pressure may be introduced through the sealed liquid. As described above, the foreign matter invasion preventing means 73 can be provided in the external pressure introducing passage 72 provided outside the pressure sensor.

FIG. 12 is a block diagram of still another gas meter L of the present invention, in which the gas flow rate of gas flowing through the metering section 82 and the gas pipe 81 (gas flow rate per unit time) is shown. Flow sensor 83 for measurement, gas pipe 81
The pressure sensor 84 according to the present invention is provided with foreign matter intrusion prevention means 84a for measuring the gas pressure inside, and a seismograph 85 for detecting an earthquake. The total amount of gas flowing in the gas pipe 81 is measured by the measuring unit 82 and displayed on a display unit (not shown) such as a meter. The gas flow rate and gas pressure in the gas pipe 81 are measured by the flow rate sensor 83 and the pressure sensor 84, respectively, and are constantly monitored by the controller 86. If a gas leak occurs, the flow rate of gas flowing through the gas pipe 81 increases abnormally. Also, if you forget to turn off the gas appliances, the gas will continue to flow for an abnormal time. Furthermore, the gas pressure flowing through the gas pipe 81 decreases before and after the gas leak and the restoration of the gas pipe construction. In the gas meter L, when the controller 86 detects an abnormality in the gas flow rate or a decrease in gas pressure, the warning lamp 88 is turned on to notify the alarm and the gas cutoff valve 87 is closed. Further, even when an earthquake is detected by the seismograph 85, the warning lamp 88 is turned on to notify the alarm and the gas cutoff valve 87 is closed. In this way, when an abnormality occurs in the gas flow rate or gas pressure, the gas pipe 81 can be automatically closed to prevent the risk of explosion or the like. Particularly, since the pressure sensor 84 is provided with the foreign matter invasion preventing means 84a, foreign matter such as dust and dirt does not enter the pressure chamber of the pressure sensor 84, and the sensitivity is not deteriorated even in long-term use. A highly reliable gas meter L can be provided. Also, FIG.
As shown in 2, the external signal 8 from the gas alarm installed in the room or the incomplete combustion alarm installed in the gas appliance, etc.
The gas shutoff valve 87 may be closed or the warning lamp 88 may be turned on by detecting 9.

FIG. 13 is a block diagram of a sphygmomanometer according to the present invention. The sphygmomanometer M includes a pressure sensor 91 according to the present invention equipped with foreign matter intrusion prevention means 91a, a cuff 92, a pump 93 and a CP.
The control unit 94 is composed of U and the like. Cuff 9
2 and the pressure sensor 91 are connected by a pressure guiding tube 95, and a pump 93 is connected to the pressure guiding tube 95.
Can send air to the cuff 92. When measuring the blood pressure, first, the cuff 92 is wrapped around the upper arm of the measurement subject, the age and sex of the measurement subject are input from the input unit 96 such as a keyboard as necessary, and the blood pressure monitor M is started. . When the control unit 94 receives the start signal from the input unit 96, it closes the control valve 98, activates the pump 93, sends air to the cuff 92 until a predetermined pressure is reached, and tightens the upper arm portion. The pressure applied to the cuff 92 is always detected by the pressure sensor 91, and when the pressure reaches a certain level, the control unit 94 stops the pump 93. Next, the control unit 94
Opens the control valve 98 to gradually remove the air in the cuff 92 to reduce the pressure. At this time, the pressure applied to the pressure sensor 91 via the pressure guiding tube 95 becomes small while changing periodically with the pressure of the blood flow flowing through the upper arm. Therefore, the systolic blood pressure, the diastolic blood pressure, and the pulse rate can be indirectly obtained by detecting the change in the pressure applied to the pressure sensor 91 via the pressure guiding tube 95 by the control unit 94. When the minimum blood pressure is obtained, the control unit 94 fully opens the control valve 98 to discharge the air in the cuff 92 to the atmospheric pressure. The obtained systolic blood pressure and diastolic blood pressure are displayed on the output unit 97 including a display or the like, or by referring to the input age or the like, it is possible to call attention to an abnormal value or the like as necessary. Since this sphygmomanometer is provided with the foreign substance invasion preventing means 91a, even if it is used for a long period of time, there are few malfunctions due to the foreign substances, and it is possible to measure blood pressure accurately forever.

In the gas meter and the blood pressure monitor described above, the embodiments using the pressure sensor of the present invention provided with the foreign matter intrusion prevention means have been described, but the pressure sensor unit of the present invention provided with the foreign matter invasion prevention means and It is also possible to use the pressure sensor unit of the present invention in which the opening of the pressure introducing path is arranged vertically downward. Needless to say, the present invention is not limited to these gas meters and sphygmomanometers, and can be applied to various pressure measuring devices using pressure sensors (or pressure sensor units).

[0052]

In the pressure sensor of the present invention, foreign matter intrusion preventing means including a dust collecting condenser, a narrow passage, a plurality of grooves or holes is provided in the pressure introducing passage, or the pressure introducing passage is opened. Since the end is arranged vertically downward, foreign matter such as dust or dirt larger than the gap between the fixed electrode and the diaphragm does not enter the pressure introducing portion from the pressure introducing path.

Further, in the pressure sensor unit of the present invention, foreign matter intrusion preventing means such as a dust collecting capacitor and a dust removing filter is provided in the pressure introducing passage provided in the sensor package, or the pressure introducing passage is opened. Since the end is arranged vertically downward, foreign matters such as dust and dirt do not enter the pressure introducing portion through the pressure introducing passage.

Therefore, due to foreign matter such as dust and dirt,
The movement of the diaphragm is not hindered, the sensitivity of the pressure sensor or the pressure sensor unit does not decrease even after long-term use, and stable operation can be performed forever.

Further, according to the present invention, it is possible to prevent a decrease in sensitivity due to dust or the like during transportation or storage, and to provide a more reliable pressure sensor and pressure sensor unit.

By using these pressure sensors and pressure sensor units, the reliability of gas meters, blood pressure monitors, etc. can be improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a pressure sensor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a pressure sensor which is another embodiment of the present invention.

FIG. 3 is a partially cutaway perspective view showing a pressure sensor which is still another embodiment of the present invention.

FIG. 4 is a partially cutaway enlarged perspective view showing a pressure sensor according to still another embodiment of the present invention.

FIG. 5 is a sectional view showing a pressure sensor which is still another embodiment of the present invention.

FIG. 6 is a sectional view showing a pressure sensor unit according to the present invention.

FIG. 7 is a plan sectional view showing another pressure sensor unit according to the present invention.

FIG. 8 is a perspective view showing still another pressure sensor unit according to the present invention.

FIG. 9 is a sectional view showing still another pressure sensor unit according to the present invention.

FIG. 10 is a partially cutaway schematic view showing a gas meter according to the present invention.

FIG. 11 is a partially cutaway enlarged schematic view showing another gas meter according to the present invention.

FIG. 12 is a configuration diagram showing still another gas meter according to the present invention.

FIG. 13 is a configuration diagram showing a sphygmomanometer according to the present invention.

FIG. 14 is a cross-sectional view showing a conventional pressure sensor.

[Explanation of symbols]

3 diaphragm 4 pressure chamber 7 pressure introducing passage 8a, 8b for pressure sensor trap electrodes 12a, 12b reference electrode 17 ventilation passage 24, 33, 43, 53 pressure introducing passage for package 26, 45, 55 pressure introduction Pipe 28 seal

Claims (15)

[Claims] 1. A fixed substrate is bonded to at least one surface of a support substrate that supports a diaphragm whose amount of flexure changes according to a change in pressure, and a first pressure introducing portion provided between the diaphragm and the fixed substrate. A pressure sensor for detecting a pressure difference between a pressure and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, wherein pressure is introduced into the first or second pressure introducing portion. And a foreign matter invasion preventing unit provided in a part or the whole of the pressure introducing passage. 2. The foreign matter invasion preventing means is a dust collecting capacitor provided in a part or the whole of the pressure introducing passage for introducing pressure to the first pressure introducing portion. The pressure sensor described in. 3. The pressure sensor according to claim 2, wherein a voltage is constantly applied to the dust collecting capacitor. 4. The pressure sensor according to claim 2, wherein the dust collecting capacitor shares at least a part with an auxiliary capacitor such as a temperature compensating capacitor. 5. The narrow passage having a gap smaller than a gap between a diaphragm and a fixed substrate, wherein the foreign matter intrusion preventing means is provided in a part of the pressure introducing passage for introducing pressure to the first pressure introducing portion. The pressure sensor according to claim 1, wherein 6. The foreign matter invasion preventing means is provided in a part of the pressure introducing passage for introducing pressure into the first pressure introducing portion and has a width smaller than a gap between the diaphragm and the fixed substrate. The pressure sensor according to claim 1, wherein the pressure sensor is a groove or a hole. 7. A fixed substrate is bonded to at least one surface of a support substrate that supports a diaphragm whose amount of flexure changes according to a change in pressure, and a first pressure introducing portion provided between the diaphragm and the fixed substrate. A pressure sensor for detecting a pressure difference between a pressure and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, wherein atmospheric pressure is applied to the first or second pressure introducing portion. A pressure sensor comprising a pressure introducing passage for introducing the pressure sensor, wherein the open end of the pressure introducing passage is arranged vertically downward. 8. A fixed substrate is bonded to at least one surface of a support substrate that supports a diaphragm whose amount of flexure changes according to pressure change, and a first pressure introducing portion provided between the diaphragm and the fixed substrate. The pressure sensor includes a pressure sensor for detecting a differential pressure between a pressure and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, and a sensor package for accommodating the pressure sensor. Alternatively, in a pressure sensor unit having a pressure introducing passage for introducing pressure to the second pressure introducing portion in the sensor package, foreign matter intrusion preventing means is provided in a part or the whole of the pressure introducing passage. Pressure sensor unit. 9. The pressure sensor unit according to claim 8, wherein the foreign matter invasion preventing means is a dust collecting capacitor provided in the pressure introducing passage. 10. The pressure sensor unit according to claim 8, wherein the foreign matter invasion preventing means is a dust removing filter provided in the pressure introducing passage. 11. The foreign matter invasion preventing means is a liquid for sealing the pressure introducing passage, and the pressure is introduced into the first or second pressure introducing portion of the pressure sensor through the liquid. The pressure sensor unit according to claim 8, wherein: 12. A fixed substrate is bonded to at least one surface of a support substrate that supports a diaphragm, the amount of flexing of which changes according to a change in pressure, and a first pressure introducing portion provided between the diaphragm and the fixed substrate. The pressure sensor includes a pressure sensor for detecting a differential pressure between a pressure and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, and a sensor package for accommodating the pressure sensor. Alternatively, in a pressure sensor unit having a pressure introducing path for introducing atmospheric pressure into the second pressure introducing section in the sensor package, the pressure is characterized in that the open end of the pressure introducing path is arranged vertically downward. Sensor unit. 13. A fixed substrate is joined to at least one surface of a support substrate supporting a diaphragm whose deflection changes with pressure changes, and a first pressure introducing portion provided between the diaphragm and the fixed substrate. The pressure sensor includes a pressure sensor for detecting a differential pressure between a pressure and a pressure of a second pressure introducing portion provided on the opposite side of the diaphragm from the pressure introducing portion, and a sensor package for accommodating the pressure sensor. Alternatively, in a pressure sensor unit having a pressure introducing passage for introducing pressure to the second pressure introducing portion in the sensor package, an end portion of the pressure introducing passage is closed by attaching a seal. Pressure sensor unit. 14. A gas meter having a function of detecting a decrease in gas pressure, wherein the pressure sensor according to claim 1 or 7,
A gas meter comprising the pressure sensor unit according to 12 or 13. 15. A sphygmomanometer for measuring blood pressure by a pressure sensor via a blood pressure detecting means such as a cuff body, wherein the pressure sensor according to claim 1 or 7,
A blood pressure monitor comprising the pressure sensor unit according to 12 or 13.