JPH0579896A - Earthquake sensor - Google Patents

Abstract

PURPOSE:To detect the vibration of an earthquake from a voltage generated due to the deformation of a piezoelectric film in the extending direction by transmitting the horizontal vibration of the earthquake to the piezoelectric film via a vibration transmitting member in the horizontal direction. CONSTITUTION:An upper end of a piezoelectric film 4 is fixed inside a box body 2 by a fixing member 5. After a weight 6 is securely attached to the lower end of the film, the film 4 is dipped into a silicone oil 3. When the box body 2 is vibrated, the silicone oil 3 sways, and the sway is transmitted to the piezoelectric film 4 in the horizontal direction. At this time, the piezoelectric film 4 is set with the tensile force applied in the up-and-down direction. Therefore, the piezoelectric film 4 is deformed in tone extending direction by the sway transmitted in the horizontal direction, whereby a voltage is generated by the piezoelectric phenomenon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration-sensing device which senses vibration caused by an earthquake and outputs a signal.

[0002]

2. Description of the Related Art In order to prevent a secondary disaster after an earthquake occurs,
There is a home-use gas meter that is equipped with a seismic sensing device for detecting vibration due to an earthquake and that shuts off a gas flow path when the seismic sensing device detects vibration. As a seismic sensing device used for such a gas meter, a seismic sensing device disclosed in Japanese Utility Model Laid-Open No. 61-48325 has a steel ball inside a casing having a conical inner bottom surface, and The vibration-sensitive switch is configured to open and close the contacts of the switch mechanism by transmitting the movement through the concave spherical surface and the pressing plate, and this vibration-sensitive switch can be swung freely within the liquid-sealed chamber via the suspension shaft. We support. With this configuration, the inclination due to an error during mounting is corrected.

[0003]

However, in the above-described conventional seismic sensing device, since the operation of the steel ball is transmitted to the contact of the opening / closing mechanism of the switch, a complicated structure such as a transmission mechanism is required, which results in cost reduction. There is a problem that it causes rise and is easily damaged by impact. Further, since vibration is detected by the movement of the steel balls on the inner bottom surface of the conical shape, it is difficult to adjust the setting sensitivity after manufacturing, and there is a problem that the yield of the products deteriorates. Furthermore, in addition to the seismic switch part, a liquid ring chamber with a complicated shape is required, which also causes an increase in the cost due to an increase in the number of parts, and the problem that it cannot be mounted on the printed circuit board due to the large size and shape. was there.

The applicant of the present invention, in Japanese Patent Application No. 2-98851, dips two piezoelectric films into a fluid at right angles to each other and squares the voltages generated on the two piezoelectric films and adds them. We proposed a seismic sensing device that squared and output the measured value, but in order to detect the voltage proportional to the magnitude of the vibration regardless of the vibration transmission direction on the horizontal plane, the square calculation or absolute value calculation (peak value) There has been a problem that a circuit for performing calculations etc. is required and the circuit configuration becomes complicated.

An object of the present invention is to detect the vibration of an earthquake by transmitting the movement of the vibration transmitting member due to the vibration of the earthquake to the piezoelectric film in the horizontal direction, and detecting the voltage generated by the piezoelectric phenomenon on the piezoelectric film to simplify the simplification. With this structure, the number of parts can be reduced, the device can be downsized, and it can be mounted on a printed circuit board, cost can be reduced, shock resistance can be improved, and setting sensitivity can be easily adjusted. To provide a device.

Further, by forming the piezoelectric film into a cylindrical shape, it is possible to detect a voltage according to the magnitude of vibration without requiring square calculation or absolute value calculation, and a complicated calculation circuit is unnecessary. An object of the present invention is to provide a seismic sensing device that can realize downsizing of the device and cost reduction.

[0007]

The seismic sensing device of the present invention comprises:
A vibration transmitting member for transmitting vibration in a horizontal direction to a single piezoelectric film having electrodes formed on both sides, a holding member for holding the piezoelectric film in a vertical direction by restricting vertical displacement of both ends thereof, and a piezoelectric film. Voltage detection means for detecting the voltage generated at the electrode via the electrode.

Further, the piezoelectric film is a cylindrical film formed in a cylindrical shape.

Further, the holding member comprises a fixing member for fixing the upper end of the piezoelectric film and a weight fixed to the lower end.

Further, the holding member is a supporting member for fixing each of the upper end portion and the lower end portion of the piezoelectric film.

Further, the vibration transmitting member is a liquid in which the piezoelectric film is immersed.

In addition, the vibration transmitting member is a weight fixed to an appropriate position of the piezoelectric film.

A vibration suppressing member is fixed to the piezoelectric film at an appropriate position.

[0014]

In the vibration-sensing device of the present invention, the vibration is horizontally transmitted from the vibration transmitting member to the piezoelectric film having the electrodes formed on both sides. This piezoelectric film is held in the vertical direction by restricting its vertical displacement, and when vibration is transmitted in the horizontal direction from the vibration transmission member, the piezoelectric film bends in the horizontal direction with almost no change in the positions of both ends. As a result, the piezoelectric film is deformed in the extension direction on both sides thereof, and this deformation generates a voltage.
The voltage generated in this piezoelectric film is detected by the voltage detecting means via the electrode.

When the piezoelectric film is formed in a cylindrical shape, the vibration transmitted by the vibration transmission member is deformed according to the vibration regardless of the vibration direction in the horizontal plane, and the voltage is detected.

Further, the upper end of the piezoelectric film is fixed by a fixing member, and the weight is fixed to the lower end of the piezoelectric film, whereby the vertical displacement of the piezoelectric film is regulated and the piezoelectric film is held in the vertical direction. be able to. At this time,
The weight acts as a vibration transmitting member for vertical vibration, and as a result, the piezoelectric film expands and contracts in accordance with the vertical vibration to generate a voltage.

Further, by bonding the weight fixed to the lower end portion of the piezoelectric film to the device, it is possible to easily fix the piezoelectric film in a state in which a vertical tension is applied.

Further, by immersing the piezoelectric film in the liquid, when the vibration sensing device vibrates, the vibration can be transmitted to the piezoelectric film through the liquid and the vibration of the piezoelectric film can be damped.

Further, by fixing the weight to the piezoelectric film at a proper position, when the vibration sensing device vibrates, the vibration is transmitted to the piezoelectric film.

In addition, by fixing the vibration suppressing member at a proper position on the piezoelectric film, it is possible to damp the vibration of the piezoelectric film, which is less affected by temperature change and vibration frequency change than in the case of liquid.

[0021]

1 is a plan sectional view and a side sectional view of a seismic sensing apparatus according to an embodiment of the present invention. The vibration-sensing device 1 stores a silicone oil 3 in a cylindrical casing 2 and includes a piezoelectric film 4 immersed in the silicone oil 3. The piezoelectric film 4 has its upper end fixed inside the housing 2 via a fixing member 5, and has a weight 6 fixed to its lower end. As shown in FIG. 2, the piezoelectric film 4 has electrodes 7a and 7b formed on the front surface and the back surface, respectively, and the projections 4a and 4b are formed to project from the base 4c in directions orthogonal to each other. These protrusions 4a and 4b
Is bent in the same direction with respect to the base portion 4c, fixed to the fixing member 5 with the base portion 4c as the upper end, and the weight 6 is fixed to the end portions of the projecting portions 4a and 4b as the lower end portions.

With the above-described structure, the weights 6 exert a vertical tension on the protrusions 4a and 4b of the piezoelectric film 4, and when the silicon oil 3 serving as the vibration transmitting member swings due to vibration, the swinging is caused. It acts on the piezoelectric film 4 in a substantially horizontal direction, and the piezoelectric film 4 tends to project and deform in the horizontal direction. At this time, since the tension in the vertical direction acts on the piezoelectric film 4, the piezoelectric film 4 has its protrusions 4a, 4a.
In b, the front surface and the back surface are deformed in the extension direction.
For vertical vibration, the weight 6 acts as a vibration transmission member,
As a result, the piezoelectric film 4 expands and contracts in accordance with the vertical vibration,
Voltage is generated. In general, the piezoelectric film 4 has a surface that generates a positive charge and a surface that generates a negative charge when deformation occurs in the extension direction, and the piezoelectric film 4 is deformed in either the front surface direction or the back surface direction. In the case of electrode 7a,
A voltage corresponding to the size of the deformation is generated between 7b.

The voltage generated between the electrodes 7a and 7b formed on the front and back surfaces of the piezoelectric film 4 is detected by the voltage detection circuit shown in FIG. The voltage detection circuit 11 includes a capacitor C, resistors R1 and R2, and a MOSFET 12. Since the piezoelectric film 4 has a high impedance, its voltage value is easily affected by noise or the like. Therefore, the impedance-converted voltage by the MOSFET 12 is taken out at the source terminal 13. This voltage detection circuit 1
In 1, the capacitance of the capacitor C becomes a factor that determines the on / off time of the MOSFET 12, and the resistors R1 and R2 determine the threshold voltage of the MOSFET 12.

The protrusions 4a and 4b of the piezoelectric film 4
By dividing the electrode formed on each of the electrodes and squared the value obtained by squaring the voltages generated at the respective protruding portions 4a and 4b and adding the squared values, the vibration transmitted from the silicon oil 3 can be changed in the vibration direction on the horizontal plane. Regardless, it is possible to detect a voltage value depending only on the magnitude of vibration.

In this case, as described above, since the piezoelectric film 4 is only deformed in the extension direction, the positive / negative of the voltage values of the protrusions 4a and 4b are not inverted depending on the direction of transmission of vibration, and the piezoelectric film 4 is not changed. It is not necessary to obtain the absolute value of the generated voltage, and the circuit configuration can be simplified as compared with the conventional one.

FIG. 4 is a plan sectional view and a side sectional view showing the structure of a seismic sensing device according to another embodiment of the present invention.
Inside the cylindrical casing 22 of the vibration-sensing device 21, a weight 26 fixed to the lower end of the piezoelectric film 24 immersed in the silicone oil 23 is adhered to the inner bottom surface of the casing 22 with an adhesive 27. As a result, the lower end of the piezoelectric film 24 is completely restricted in displacement in the vertical and horizontal directions. On the other hand, the upper end portion of the piezoelectric film 24 is fixed by the fixing member 25, and the swing of the silicon oil 23 causes the piezoelectric film 24 to be completely converted into only the deformation in the extending direction.

FIG. 5 is a plan sectional view and a side sectional view showing the structure of a seismic sensing apparatus according to still another embodiment of the present invention. The vibration-sensing device 31 is a device in which a single piezoelectric film 34 is wound in a cylindrical shape inside a cylindrical casing 32, and a silicon gel 35 as a vibration suppressing member having a predetermined thickness is attached to the outer periphery thereof. is there. Inside the cylindrical piezoelectric film 34, a weight 37 held in a silicon gel 36 is provided. The weight 37 is stopped by the silicon gel 36 at an intermediate position in the vertical direction of the piezoelectric film 34.

According to this embodiment having the above-mentioned structure,
When the vibration-sensing device 31 senses an earthquake motion and vibrates, the weight 37 vibrates in the horizontal direction, and this vibration is transmitted to the inner peripheral surface of the piezoelectric film 34. The piezoelectric film 34 is fixed to the inner upper surface and the inner bottom surface of the housing 32 at the upper and lower ends thereof, and the piezoelectric film 34 is deformed in the extension direction by the movement of the weight 37. Electrodes 38a and 38b are formed on the front surface and the back surface of the piezoelectric film 34, respectively, as shown in FIG. 6, and the voltage generated by the deformation of the piezoelectric film 34 in the extension direction is transmitted through the electrodes 38a and 38b. It is detected by the voltage detection circuit shown in FIG.

By thus forming the piezoelectric film 34 in a cylindrical shape, the piezoelectric film 34 is deformed according to only the magnitude of the vibration regardless of the vibration transmission direction in the horizontal plane, so that the vibration transmission in the horizontal plane is performed. There is no need to perform a square operation to ignore the influence of the direction,
The circuit configuration can be simplified.

As the vibration suppressing member, instead of the silicone gel 35, silicone oil having an appropriate viscosity may be filled outside the piezoelectric film 34. Also, the weight 37
Can be made unnecessary by forming a high-mass portion in a portion of the vibration suppressing member located at the vertical center of gravity of the piezoelectric film 34. That is, the weight 37 can be replaced by increasing the amount of the silicon gel 36 in the central portion.

[0031]

According to the present invention, the vibration generated by an earthquake is horizontally transmitted to the piezoelectric film via the vibration transmitting member, and the voltage generated in the piezoelectric film by the deformation of the piezoelectric film in the extension direction is detected. By doing so, it is possible to accurately detect an earthquake with an extremely simple configuration that does not require a structure such as a transmission mechanism. As a result, cost reduction can be realized, the device can be downsized, and mounting on a printed circuit board can be dealt with.

Further, by forming the piezoelectric film in a cylindrical shape, the influence of the transmission direction of vibration on the horizontal plane can be neglected without using an arithmetic circuit for performing square calculation or the like.

The vertical movement of both end faces of the piezoelectric film can be easily realized by fixing the upper end portion and providing the lower end portion with a weight.

Furthermore, the piezoelectric film can be easily stretched by adhering this weight to the inside of the apparatus.

In addition, the vibration of the piezoelectric film can be suppressed by using a liquid having a predetermined viscosity for the vibration transmitting member.

Further, there is an advantage that the manufacturing process can be simplified by using the weight fixed to the proper position of the piezoelectric film as the vibration transmitting member.

Furthermore, by attaching a vibration suppressing member to the piezoelectric film, the vibration of the piezoelectric film can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a plan sectional view and a side sectional view showing a configuration of a seismic sensing apparatus that is an embodiment of the present invention.

FIG. 2 is a diagram showing a front surface and a back surface of a piezoelectric film used in the same vibration-sensing device.

FIG. 3 is a diagram showing a configuration of a voltage detection circuit used in the seismic sensor.

FIG. 4 is a plan sectional view and a side sectional view showing a configuration of a seismic sensing device according to another embodiment of the present invention.

FIG. 5 is a view showing a front surface and a back surface of a piezoelectric film used in the seismic sensing device according to the another embodiment.

6A and 6B are a plan sectional view and a side sectional view showing a configuration of a seismic sensing apparatus according to still another embodiment of the present invention.

[Explanation of symbols]

 1-Vibration Sensing Device 2-Housing 3-Silicon Oil (Vibration Transmission Member) 4-Piezoelectric Film 5-Fixing Member 6-Weight 7a, 7b-Electrode

Claims (7)

[Claims] 1. A vibration transmitting member for transmitting vibration in a horizontal direction to a single piezoelectric film having electrodes formed on both sides, and a holding for holding the piezoelectric film in a vertical direction by restricting vertical displacement of both ends of the piezoelectric film. A vibration-sensing device comprising: a member; and a voltage detecting unit that detects a voltage generated in a piezoelectric film via the electrode. 2. The seismic sensing device according to claim 1, wherein the piezoelectric film is a cylindrical film formed in a cylindrical shape. 3. The seismic sensing device according to claim 1, wherein the holding member includes a fixing member that fixes the upper end of the piezoelectric film and a weight that is fixed to the lower end. 4. The seismic sensing device according to claim 1, wherein the holding member is a support member that fixes each of an upper end portion and a lower end portion of the piezoelectric film. 5. The vibration-sensing device according to claim 1, wherein the vibration transmitting member is a liquid in which the piezoelectric film is immersed. 6. The vibration-sensing device according to claim 1, wherein the vibration transmitting member is a weight fixed to an appropriate position of the piezoelectric film. 7. The vibration-sensing device according to claim 1, wherein a vibration suppressing member is fixed to an appropriate place of the piezoelectric film.