JP2001324513A - Acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid type sensor having stable output characteristics irrespective of a vibration frequency. SOLUTION: An acceleration sensor 1 is constituted in such a way that a sealed vessel consists of a metallic housing 2 which becomes a main electrode and a lid plate 3 and a plurality of auxiliary electrodes (4A, 4B, 4C,...) are provided at an equal interval in a condition in which they are insulated from each other in the sealed vessel. The sealed vessel contains a conductive liquid 6, and a contact area of the auxiliary electrodes (4A,...) and the conductive liquid 6 is changed when the acceleration sensor 1 changes an angle and a direction of inclination to change a resistance value between the main electrode and the auxiliary electrodes. Suppressing members (7A, 7B, 7C,...) for suppressing abrupt flow of the conductive liquid are provided in the vessel. The behavior of the conductive liquid close to a resonance frequency is suppressed by suppressing a flow of the conductive liquid by the suppressing members to stabilize a sensor output and facilitate the processing of a signal from the acceleration sensor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor capable of obtaining a horizontal acceleration as a continuous signal corresponding to its magnitude.

[0002]

2. Description of the Related Art Hitherto, various types of acceleration sensors for detecting acceleration in the horizontal direction have been proposed. Among them, as a sensor having uniform characteristics in all directions to detect an object whose acceleration direction to be detected cannot be specified, such as an earthquake, there is a seismic sensor disclosed in Japanese Patent No. 2892559 by the present applicant. .

[0003] In this seismic device, a metal conductive ball is arranged in a metal container having a gently inverted conical bottom.
When an acceleration of a predetermined value or more is applied to the seismic sensor, the conductive sphere rolls from the center of the bottom surface and comes into contact with electrodes arranged around the conductive sphere.
By electrically connecting the electrode and the container via the conductive sphere in this manner, it is possible to output as a signal that an acceleration of a predetermined value or more has been applied.

However, since this seismic sensor has a structure in which electric paths are connected and disconnected by conductive balls, it is only possible to determine whether the applied acceleration is less than a predetermined value or more. Was.

On the other hand, as an acceleration sensor capable of obtaining a signal corresponding to the magnitude of acceleration, there is an acceleration sensor using a semiconductor, for example. This semiconductor type acceleration sensor, for example, holds a weight portion with a beam and outputs an electric signal according to the amount of distortion generated in the beam portion due to acceleration. Usually, by combining two or more detection units, It forms a sensor that detects acceleration in all directions. Although this acceleration sensor can provide a small and sensitive sensor, it is vulnerable to excessive input due to impact or the like and requires careful handling during manufacturing and installation. There is also a device provided with a buffer mechanism for protecting the detection unit against an excessive input, but there is a problem that the structure becomes complicated and the cost increases.

Other than these, there are, for example, those using an optical fiber gyro and those using a magnet and a coil. However, it is difficult to reduce the size of the sensor itself, and the cost is high.

Therefore, the present applicant proposes an acceleration sensor as shown in FIG. 7 in Japanese Patent Application No. 11-129280 or the like as an acceleration sensor which is small and outputs a continuous signal corresponding to the magnitude of acceleration and is easy to handle. did. The acceleration sensor 101 includes a metal housing 102 and a cover plate 1.
03 constitutes a closed housing. A plurality of conductive terminals are inserted into the cover plate 103 and are insulated and fixed.
In this example, there are four conductive terminals 104A, 104B, 104C and 104D (not shown) which are arranged at equal intervals and are insulated from each other, and
2 are equidistant from each other. A conductive liquid 105 is sealed in the closed container, and each of the conductive terminals is electrically connected to the housing 102 and the cover plate 103 with a predetermined resistance value.

When the acceleration sensor 101 receives an acceleration, the liquid surface 105A of the conductive liquid 105 is inclined, for example, as shown at 105B according to the direction and magnitude of the acceleration.
When the liquid surface is inclined in this manner, each conductive terminal 104
The contact area between A to 104D and the conductive liquid 105 changes. Thus, by comparing the change in resistance between each conductive terminal and the housing, the magnitude and direction of the acceleration received by the acceleration sensor 101 can be known. In addition, since the change in the resistance value according to the change in the magnitude and direction of the acceleration has a good response, for example, when used as a seismic sensor, a control device driven by a signal from this sensor is used as a control target device. Appropriate processing corresponding to the vibration can be performed.

Also, when an overload due to an impact or the like is applied, the driving portion is not a solid but only a liquid and the stress does not concentrate on a specific portion. It is unlikely to be out of order or damaged.

[0010]

This acceleration sensor 1
The output characteristic with respect to the vibration frequency, that is, the frequency characteristic of the change in the resistance value when the acceleration of the same magnitude is given to 01 is shown as a curve 111 in the graph of FIG. As can be seen from this graph, the sensitivity of the acceleration sensor 101 increases around 10 Hz as compared with the change amount at a relatively low frequency vibration, and decreases in a higher vibration frequency region. The change in the resistance value is reduced in the high vibration frequency region because the flow of the liquid does not sufficiently follow the vibration due to viscosity or the like, and the resistance change, that is, the output as a sensor is reduced. Specifically, although there is a slight difference in the size of the container, the viscosity of the liquid, and the like, in this example, the sensor output is reduced with respect to vibration having a frequency exceeding 15 Hz.

Normally, the main frequency range of the seismic wave is 10 Hz or less, especially 1 to 5 Hz. Vibration in a range exceeding the frequency range is limited to living vibrations caused by impacts such as when something hits the device equipped with the sensor. When the acceleration sensor 101 is used for a seismic sensor, it is convenient that the sensitivity is reduced in a high vibration frequency region exceeding 15 Hz as described above.

However, the sensitivity of the sensor is very high in the vibration frequency region around 8 to 10 Hz. For example, in this example, a resistance change of about 4 to 5 times occurs as compared with a range of 1 to 3 Hz. This is because the resonance frequency of the liquid, determined by the size of the container and the viscosity of the liquid, is 8
Since the liquid crystal exists around 10 Hz to 10 Hz, the behavior of the liquid increases in a frequency region before and after the frequency. Therefore, a change in the contact area between the conductive liquid 105 and the conductive terminal 104 and a change in the resistance value accompanying the change are large.

In practice, the change in voltage between the electrodes of the sensor due to the change in resistance is integrated as an output signal by an electronic circuit and input to a processing device, and this signal is integrated to suppress the generation of a peak signal due to resonance. Can also. This processing will be described with reference to FIG. Note that, for simplicity, only the virtual straight line direction connecting the conductive terminals 104A and 104B will be described. Needless to say, the size is required.

The acceleration sensor 101 has a conductive terminal 104A.
, And 104B and the housing 102 are each connected by a conductive liquid 105 to form variable resistors Ra and Rb. The conductive terminals 104A and 104B are connected to fixed resistors R1 and R2, respectively, and form a Wheatstone bridge circuit (hereinafter, referred to as a bridge circuit) together with the above-described variable resistors Ra and Rb. In this bridge circuit, the common terminal E of the fixed resistors R1 and R2 and the housing 102 are connected to a detection power supply V and a measurement reference voltage is applied. Here, the power source is an alternating current such as a sine wave or a rectangular wave in order to prevent a change in resistance value due to electrolysis or polarization of the liquid. Thus, the voltage between the intermediate points X1 and X2 of the bridge circuit to which the reference voltage is applied is measured.

Normally, when the acceleration sensor 101 is in a normal posture and is not receiving acceleration due to vibration or the like, the liquid level is in the state of 105A in FIG.
a and Rb and the fixed resistors R1 and R2 are balanced, and no voltage is generated between the intermediate points X1 and X2. When any acceleration is applied in a virtual linear direction connecting the conductive terminals 104A and 104B, the conductive liquid 105 inside the acceleration sensor 101 flows to be in a state like a liquid level 105A, for example. Therefore, the contact area with each of the conductive terminals 104A and 104B changes, and one of the resistance values of the variable resistors Ra and Rb increases and the other decreases, and the balance of the bridge circuit is lost. As a result, a potential difference occurs between the intermediate points X1 and X2, and this voltage becomes an output signal of the acceleration sensor. From this output signal, the amount of inclination of the liquid 105 with respect to the housing 102 can be determined, and the magnitude of the acceleration or the amount of inclination of the acceleration sensor can be known.

The processing of the output signal is described in detail in the above-mentioned Japanese Patent Application No. 11-129280 or the like, but its outline will be described here. The output signal is actually processed as an integrated value picking up only a point synchronized with, for example, the highest positive value during one cycle of the AC voltage applied from the power supply V. The signal after this processing is an acceleration sensor Since there is no difference from the case where the DC voltage is applied to the first embodiment, the description will be made ignoring the change in the AC voltage for convenience of explanation. The output voltage from the acceleration sensor is, for example, a sinusoidal waveform. When a relatively low frequency vibration acceleration of 5 Hz or less is applied to the sensor, the output voltage is substantially proportional to the magnitude of the vibration acceleration. On the other hand, in the vicinity of the resonance frequency, the movement of the liquid increases, so that the output voltage also increases. At higher frequencies, the output voltage decreases because the conductive liquid cannot follow the vibration.

The output signal is subjected to signal processing for correcting an increase in output near the resonance frequency, and is sent to the control device. In this signal processing, the output signal from the acceleration sensor is measured a predetermined number of times for a predetermined sampling time, and the measured signal is integrated. When the output from the acceleration sensor is integrated, the data is averaged. Therefore, even if, for example, a single noise is mixed with the data, the protruding portion is averaged by other data, and the influence is effectively canceled.

Here, in the case of low-frequency vibration, the amount of change in the sensor output itself during the sampling time for one integration process is small, so that the correction rate of the processed signal with respect to the sensor output is small. On the other hand, for a relatively high frequency vibration, the change in the sensor output during the sampling time for one integration process is large, so that the correction rate is high. For example, assuming that the sampling time for the integration processing is 0.1 second, the sensor output for a vibration of 5 Hz, that is, a vibration of 0.2 seconds, is integrated for 0.5 cycle. In this case, the maximum value of the sine wave vibration is 7
It is corrected to about 0%. Further, in the case of a vibration of 10 Hz, that is, a cycle of 0.1 second, the integration of the sensor output for one cycle cancels out the increase / decrease of the output and is regarded as substantially zero. As described above, since the correction rate of the signal from the acceleration sensor gradually increases as the cycle of the vibration approaches the above-described sampling time, the increase in the output from the acceleration sensor, which increases as the resonance frequency approaches, is effectively reduced. Will be corrected. In addition, in the case of vibration of a frequency higher than the target frequency, as described above, the conductive liquid cannot sufficiently follow up, and the output decreases. Signal is smaller than

By performing the signal processing as described above, the sensitivity of the detection circuit can be substantially eliminated with respect to vibration at an arbitrary frequency, for example, vibration at a resonance frequency.

However, if the rate of increase of the sensor output at the resonance frequency is extremely high, this signal processing may not be sufficient. For example, the aforementioned conventional acceleration sensor 101
In the case of, as shown by the curve 111 in FIG. 8, the change in resistance of the sensor is as large as about 4 to 5 times near the resonance frequency as compared with the case of the frequency range where the change is low, and the rising tendency is steep. The signal correction by the integration process does not work sufficiently. For this reason, if the peak value cannot be sufficiently removed as shown by the curve 121 in FIG. 9, or if the peak voltage is corrected to match the value in the low frequency range, the sensitivity to the vibration frequency before and after the peak voltage is lowered unnecessarily. There is a problem to say that. Therefore, if the seismic wave contains vibration in this vibration frequency range, the change in resistance value will reach a predetermined amount even if the seismic intensity does not reach the predetermined seismic intensity. Or the processing device driven by a signal from the sensor may not be able to perform appropriate processing. Therefore, there is a need for a liquid sensor that suppresses the occurrence of a resonance phenomenon.

[0021]

The acceleration sensor according to the present invention has a substantially cylindrical hermetic container having both ends closed, in which a main electrode and a plurality of sub-electrodes are insulated from each other. The sub-electrodes are provided at the same distance from the main electrode and are arranged at equal intervals, and a conductive liquid is sealed in a closed container and the amount of the conductive liquid is regulated. In the posture, at least a part of the sub-electrode is located on the liquid surface, and when the inclination angle and the inclination direction of the closed container can be changed from the normal posture, the contact area between the sub-electrode and the conductive liquid changes. Then, the resistance between the main electrode and the sub-electrode is changed, and a suppression member for suppressing a rapid flow of the liquid is provided in the container.

By providing a restricting member in the container to narrow the flow path of the conductive fluid, the slow flow of the liquid mainly due to the low frequency vibration is not largely affected at the resonance frequency. Since only the behavior due to the fast flow of the liquid is suppressed, the change in the resistance value near the resonance frequency can be suppressed.

Further, according to the acceleration sensor of the present invention, the closed container is constituted by a cylindrical metal housing having one end closed and a metal disk fixedly abutted on the opening of the metal housing. By using the metal housing and the disk as the main electrode, the housing and the disk can be used as the main electrode, and the sealed container is strong, airtight and liquid-tight, and stabilizes the characteristics of the conductive liquid for a long period of time. It is possible to provide an acceleration sensor that maintains the acceleration.

According to the third aspect of the present invention, since four sub-electrodes of the acceleration response element are arranged at equal intervals, it is possible to reliably detect a change in the resistance value with respect to the acceleration in the orthogonal direction. Can be.

Further, by fixing the suppression member as a plate-like member to each sub-electrode, the effective area of the electrode can be increased, so that a liquid having a relatively high resistance value can be used.

Further, by using the plate-like member provided between the sub-electrodes as the suppressing member, the fixing operation of the suppressing member becomes easier.

Further, by disposing the plate-shaped suppressing member radially with respect to the center of the container, it is possible to effectively suppress, particularly, a wavy flow in the circumferential direction due to resonance of the liquid.

[0028]

FIG. 2 is a longitudinal sectional view of an acceleration sensor according to the present invention, and FIG.
This will be described with reference to FIG. The acceleration sensor 1 forms a closed container by a metal housing 2 having one end closed and a metal lid plate 3 for closing an opening of the metal housing 2. A plurality of, in this example, four, through holes 3A are provided in the cover plate 3, and sub-electrodes 4A, 4B, 4C, 4D made of metal conductive terminals are inserted through each of the through holes. It is hermetically insulated and fixed by the insulating filler 5.

A predetermined amount of the conductive liquid 6 having a predetermined specific resistance value and a predetermined viscosity is sealed in the closed container. Each of the sub-electrodes has a plate-shaped metal restraining member 7A, 7B, 7A.
C and 7D are fixed. These suppression members 7A to 7D are preferably arranged so as to face radially with respect to the center of the container.
Although the flow path of the liquid immersed therein and traversing the inside of the container is narrowed, it does not prevent the flow of the liquid itself.

These suppressing members 7A to 7D are conductively connected to respective metal terminals so as to be substantially radial from the center of the container as shown in FIG. Suppression member 7
A to 7D are made of metal and arranged so as not to touch each other, and the conductive liquid 6 passes between the respective restraining members and between the housing 2 or the cover plate 3 and each of the restraining members to pass through the closed container. It has been made available for distribution. In this manner, the acceleration sensor 1 uses the metal housing 2 and the cover plate 3 as main electrodes, and connects the sub-electrodes 4A to 4D and the suppression members 7A to 7D fixed to the respective electrodes by the conductive liquid 6. .

When acceleration is applied to the acceleration switch 1, the conductive liquid 6 flows in the container. At this time, since the conductive liquid 6 flows between the suppression members 7A to 7D and the cover plate 3 or the housing 2 or a gap between the suppression members, the liquid 6 is supplied according to the magnitude and direction of the acceleration as in the above-described conventional example. The surface is inclined, and the contact area between each sub-electrode and the suppressing member and the conductive liquid changes. Here, the flow path of the conductive liquid 6 is controlled by the suppression members 7A to 7A.
The flow velocity is suppressed by the flow path resistance because the flow velocity is narrowed by D. However, when the flow velocity is low, the influence is small and the influence increases as the flow velocity increases.

More specifically, in the case of vibration, the flow speed of the liquid increases as the frequency increases, so that the effect of suppressing the flow velocity by providing the suppression member and narrowing the substantial flow path also increases. In this example, as shown by a curve 31 in the graph of FIG. 8, the flow velocity of the liquid is relatively slow with respect to the vibration of 1 to 5 Hz which is the center of the seismic wave as compared with the related art, , There is substantially no effect on the amount of change in the resistance value. On the other hand, by suppressing the flow velocity of the liquid in a frequency range of about 8 to 9 Hz or higher in which the conductive liquid 6 causes resonance, and by suppressing the occurrence of a large fluctuation of the liquid surface tilt amount due to the resonance phenomenon. In addition, the amount of change in the resistance value can be suppressed as compared with the related art. In addition, since vibrations in a frequency region of 10 Hz or more can be regarded as life vibrations as described above, there is no substantial problem even if the flow rate of the liquid is suppressed by the suppressing member and resistance change does not easily occur. Therefore, even if a vibration combined with a vibration wave of a wide frequency range of about 10 Hz like a seismic wave is applied to the sensor, a reliable and accurate sensor output can be performed.

As described above, by providing the suppressing member in the container and partially narrowing the flow path of the liquid, particularly by suppressing the flow velocity of the liquid near the resonance frequency, the wavy motion of the liquid is expanded by resonance. In addition, it is possible to suppress the increase in the change in the resistance between the electrodes. In addition, since the flow path along the wall surface of the housing is restricted by arranging the suppressing member radially with respect to the center of the container, the wavy flow along the wall surface of the liquid is effectively converged, The inclination of the liquid surface is prevented from becoming excessive due to the coincidence between the wave generated in the vibration direction and the flow along the wall surface.

For example, in the case where the effect of the wave-like motion propagating along the wall in the container is almost negligible and substantially negligible, for example, as shown in FIG. . Also in this case, each restraining member 17
It goes without saying that there is a gap between them and they are not electrically connected directly. In particular, in the case where the restraining members are arranged so as to face radially with respect to the center of the container as shown in FIG. 2, all the restraining members may be attached to the cover plate or the housing and arranged between the conductive members. good. Further, in this embodiment, the case where the metal housing and the lid plate are used as the main electrodes and the conductive terminals electrically insulated and fixed to these are used as the sub-electrodes has been described as an example. When the whole container is made of an electrically insulating material such as glass, it goes without saying that the same applies even when a conductive terminal serving as a main electrode is inserted and fixed in the center of the conductive terminal serving as a sub-electrode in the container. No.

In the above-described example, the suppression member can be attached to an arbitrary position of the sub-electrode or the cover plate, so that the liquid flow path can be relatively freely secured, but the number of parts is large and the operation is rather complicated. It is. Therefore, in another example of the present invention, the suppression member is integrally mounted. This example will be described with reference to FIGS. Note that the same components as those described in the above-described example are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 4 is a longitudinal sectional view, and FIG.
In the acceleration sensor 21 shown in the B sectional view, the conductive liquid 6 is placed in a closed container constituted by the housing 2 and the cover plate 3.
At the same time, a suppressing member 27 made of an electric insulating material such as a synthetic resin is enclosed. As shown in FIG. 6, the suppressing member 27 includes a substrate 27A and a plurality of plate-like portions 27 integrated with the substrate.
B. Since the substrate 27A is disposed on the cover plate 3, through-holes 27C are provided at positions corresponding to the sub-electrodes 4A to 4D, and each sub-electrode is inserted into these through-holes during assembly. Plate-shaped part 2 for sub-electrode
The position of 7B is determined as shown in FIG. The plate-like portion 27B
Abuts on the closed inner surface of the housing 2 to determine the position of the container with respect to the central axis direction.

Also in this suppressing member 27, the conductive liquid 6
Is the same as in the above-described example, and the conductive liquid 6 has a substantial resistance due to the resistance when flowing in the narrow space between the plate portions 27B or between the plate portion 27B and the inner wall of the housing 2. Since the flow velocity is reduced, the wavy flow is suppressed, and the amplification of the wave due to resonance hardly occurs. Further, the plate-like portions 27B are arranged radially with respect to the center of the container, but the arrangement is not limited to this, and a plurality of plate-like portions may surround the center of the container as in the example of FIG. Needless to say.

Although the suppressing member 27 is made of an electrically insulating synthetic resin or the like as an example, the suppressing member 27 may be formed by using a substrate as a metal and arranging a plate portion on the substrate. In this case, the position of the plate-like portion can be reliably determined by making the through-hole for passing the sub-electrode sufficiently large so as not to contact the sub-electrode and fixing the substrate on the cover plate by welding or the like. In addition, if the positional relationship can be surely grasped at the time of assembling, the suppressing member does not necessarily need to be installed on the sub-electrode or the cover plate, and may be fixed to the inner surface of the housing.

The output signal of the acceleration sensor is input to a processing device and integrated therein in the same manner as in the above-described conventional example.
This processing will be described again with reference to FIG. It should be noted that, similarly to the above, the sub-electrode 4A
Only the case in which the acceleration in the virtual straight line direction connecting the acceleration and the direction 4B is received will be described, but it goes without saying that the acceleration in the direction perpendicular to the acceleration can be similarly detected.

The acceleration sensor 1 forms variable resistances Ra and Rb by connecting the sub-electrodes 4A and 4B and the housing 2 with a conductive liquid 6, respectively. Sub electrode 4
A and 4B are connected to fixed resistors R1 and R2, respectively, and constitute a bridge circuit together with the variable resistors Ra and Rb. The common terminal E of the fixed resistors R1 and R2 of the bridge circuit and the housing 2 are connected to a power supply V, and a reference voltage for measurement is applied. Thus, the voltage between the intermediate points X1 and X2 of the bridge circuit to which the reference voltage is applied is measured.

Normally, when the acceleration sensor 1 is in the normal posture and is not receiving acceleration due to vibration or the like, the variable resistors Ra and Rb and the fixed resistors R1 and R2 are balanced, and a voltage is generated between the intermediate points X1 and X2. do not do. When acceleration is applied in the virtual linear direction connecting the sub-electrodes 4A and 4B, the conductive liquid 6 flows and the liquid surface is inclined, so that the contact area between the sub-electrodes 4A and 4B changes. Therefore, one of the resistance values of the variable resistors Ra and Rb increases and the other decreases, and the balance of the bridge circuit is lost. As a result, a potential difference occurs between the intermediate points X1 and X2, and this voltage becomes an output signal of the acceleration sensor.

As described above, this output signal has a complicated waveform that is linked to both the cycle of the AC voltage from the power supply and the cycle of the vibration acceleration. Here, as in the above-described example, the DC voltage is applied to the acceleration sensor. Description will be made assuming that the voltage is applied. In the present invention, the flow path of the conductive liquid 6 is narrowed by providing the suppression plate in the closed container and the flow of the liquid is slowed down. The shape almost corresponds to the waveform of the vibration acceleration. In contrast, for relatively high frequency vibrations, the effect of the flow path resistance on the movement of the liquid is greater. In the embodiment, the extreme action of the liquid is suppressed by the effective operation of the suppressing plate with respect to the movement of the liquid in the vibration near the resonance frequency or the vibration of the frequency higher than the resonance frequency. As shown by a curve 31 in FIG. 8, the peak value of the output signal increases about twice as much as that at a low frequency without the influence of resonance, and is less than half as compared with the peak value of the above-mentioned conventional product. Can be suppressed.

The integration process for this output signal will be described. First, the number of data in one integration process is one cycle in the target frequency oscillation. The target frequency is set to a frequency that effectively corrects an increase in output near the resonance frequency and does not affect a normal output signal, particularly a signal due to vibration in a frequency domain due to an earthquake. For example, a case where the resonance frequency of the sensor is 9 Hz and the target frequency is 10 Hz will be described. In this case, one cycle of the target frequency of 10 Hz is 0.1
Seconds. On the other hand, if the sampling frequency is 1000
Assuming that the sampling frequency is Hz, the sampling period for one integration process is 0.1 second by setting the sampling number to 100 data, which coincides with the period of the target frequency.

When the data sampled under these processing conditions is integrated, the change in data during one sampling time, 0.1 second in this example, is small for vibration having a frequency sufficiently lower than the target frequency. It can be considered that substantial correction is hardly performed even when the integration process is performed. On the other hand, the signal for the vibration of 10 Hz, which is the target frequency, is obtained by integrating the value of one cycle, so that the output signals accompanying the increase and decrease of the resistance value cancel each other, and become substantially zero. Is considered. As the signal from the acceleration sensor increases its correction amount sequentially as the vibration frequency approaches the above-mentioned target frequency, the increase in the output from the acceleration sensor that increases as it approaches the resonance frequency is effectively corrected. You.

In particular, in the present invention, the suppression member for suppressing the flow of the liquid is provided inside the acceleration sensor to narrow the flow path of the liquid. , The correction becomes easier, and as shown by the curve 41 in FIG. 9, the corrected signal can obtain substantially uniform frequency characteristics over a wide range. Therefore, if the vibration is within a predetermined frequency range from a long-period vibration to a detection signal due to vibration of an arbitrary frequency, a stable signal corresponding to the magnitude of the vibration, that is, the magnitude of the acceleration is obtained regardless of the frequency component. Therefore, particularly when used for a seismic sensor, a reliable and appropriate treatment can be performed according to the magnitude of the shaking caused by the earthquake.

In the above example, signal processing for repeated vibrations has been described on the premise that the acceleration sensor of the present invention is used for a seismic sensor. Of course,
It can also be used as a tilt sensor that can detect the tilt angle from the tilt between the container and the liquid level.

[0047]

As described above, according to the acceleration sensor of the present invention, even when a liquid is used as the inertial body, the behavior of the liquid due to the resonance frequency can be suppressed and the sensor output can be further stabilized. Signal processing can be easily performed, and the output signal from the acceleration sensor at the same acceleration can be processed so as to be substantially uniform regardless of the frequency component of the vibration.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of an acceleration sensor of the present invention.

FIG. 2 is a sectional view of the acceleration sensor shown in FIG.

FIG. 3 is a cross-sectional view showing another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing another embodiment of the present invention.

5 is a sectional view of the acceleration sensor shown in FIG.

FIG. 6 is an embodiment of a suppressing member used in the acceleration sensor of FIG. 4;

FIG. 7 is a longitudinal sectional view showing a conventional acceleration sensor.

FIG. 8 is a graph showing frequency characteristics of resistance between terminals of the acceleration sensor.

FIG. 9 shows an example of a signal obtained by correcting the output from the acceleration sensor.

FIG. 10 shows an example of a circuit using an acceleration sensor.

[Explanation of symbols]

 1:21: acceleration sensor 2: housing 3: lid plate 4A, 4B, 4C, 4D: sub-electrode 6: conductive liquid 7A, 7B, 7C, 7D, 17, 27: suppression member

Claims (6)

[Claims] A closed container having a substantially cylindrical shape with both ends closed, a main electrode and a plurality of sub-electrodes are provided in a state insulated from each other, and each of the sub-electrodes is connected to the main electrode. The conductive liquid is sealed in the closed container, and the amount of the conductive liquid is set such that at least a part of the sub-electrode has a liquid surface in a normal posture. When the closed container can change the inclination angle and the inclination direction from the normal posture, the contact area between the sub-electrode and the conductive liquid changes, and the resistance between the main electrode and the sub-electrode changes. An acceleration sensor having a variable value, and a suppression member for suppressing a rapid flow of liquid is provided in the container. 2. An airtight container for an acceleration response element comprises a cylindrical metal housing having one end closed and a metal disk fixed to an opening of the metal housing. The metal housing and the disk are mainly used. The acceleration sensor according to claim 1, wherein the disk is an electrode, and a metal lead terminal serving as a sub-electrode is fixed through the disk in an electrically insulating manner. 3. The acceleration sensor according to claim 1, wherein four sub-electrodes of the acceleration response element are provided. 4. The acceleration sensor according to claim 1, wherein the suppression member is a plate-like member fixed to each sub-electrode. 5. The method according to claim 1, wherein the suppressing member is a plate-like member disposed between the sub-electrodes.
The acceleration sensor according to the item. 6. The container according to claim 4, wherein the restraining member is disposed radially with respect to the center of the container.
The acceleration sensor according to 1.