JP3097173B2 - Seismic sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic sensor for detecting occurrence of an earthquake using a vibration sensor.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a schematic configuration of a conventional seismic sensor. The conventional seismic device 51 includes a capacitance change type vibration sensor 52 and a signal processing circuit 53. The vibration sensor 52 detects vibration and outputs a sensor output to the signal processing circuit 53 as a change in capacitance between electrodes. . The signal processing circuit 53 extracts a vibration waveform from the sensor output of the vibration sensor 52, compares the vibration waveform with seismic wave data stored in an IC card, a memory, or the like, and analyzes the vibration waveform. We judge whether it is vibration other than earthquake.

[0003]

However, a vibration sensor used for a seismic sensor has a movable electrode provided on a mass supported by a thin beam and a fixed electrode provided opposite to the movable electrode. When a vibration is sensed, the beam bends and the mass is displaced, and a change in interelectrode capacitance between the movable electrode and the fixed electrode is output as a sensor output (see FIG. 2). .

[0004] The vibration sensor has a structure in which the beam portion is very weak, and a large stress is generated in the beam every time vibration occurs. Therefore, when used for a long time or when an impact exceeding the limit is applied, the beam portion may be broken or the characteristics as a sensor may be changed. As a result, the seismic sensor malfunctions, and even if an earthquake occurs, no seismic output is output, which may cause serious damage.

[0005] Further, in the conventional test of the seismic sensor at the time of shipment, mechanical vibration is applied to the seismic sensor to check whether it is operating normally. There was a problem that the cost was high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described drawbacks of the conventional example, and has as its object the purpose of automatically diagnosing the presence / absence of a failure simply by applying a diagnostic voltage to a vibration sensor. Is to do so.

[0007]

According to the present invention, a vibration sensor detects a vibration and outputs a change in capacitance between the electrodes as a capacitance change type vibration sensor. Signal processing means for determining occurrence; and self-diagnosis means for applying a plurality of different levels of voltage between the electrodes of the vibration sensor and determining whether or not a failure has occurred based on a change in capacitance output from the vibration sensor. It is characterized by:

[0008]

[Function] A plurality of different levels of electric current are applied between the electrodes of the vibration sensor.
When pressure is applied, the distance between the electrodes changes due to the electric field generated between the electrodes. At this time, if the beam supporting the electrodes is broken, the change in the distance between the electrodes is different from that in the normal state. This change in the distance between the electrodes is a change in the capacitance between the electrodes.
Since the output from the vibration sensor, between the electrodes of the vibration sensor
By detecting the sensor output of the vibration sensor while applying a plurality of different levels of voltage , it is possible to check whether the vibration sensor has failed.

Therefore, it is possible to diagnose an abnormality of the seismic sensor without giving vibration to the seismic sensor, and to easily perform the inspection of the seismic sensor.

[0010]

FIG. 2 shows a vibration sensor 2 used for a seismic sensor.
FIG. The diaphragm 7 has a mass 10 supported in a cantilever manner by a thin beam 9 at the center of the frame 8, and a movable electrode 1 is provided on the lower surface of the mass 10.
1 is provided. The diaphragm 7 is mounted on a base 12, the lower surface of the frame 8 is adhered to the upper surface of the base 12, and the fixed electrode 13 is provided on the upper surface of the base 12 so as to face the movable electrode 11. A small gap is formed between the movable electrode 11 and the fixed electrode 13. A cover 15 is attached to the upper surface of the diaphragm 7 via a spacer 14, and the beam 9 and the mass 1
0 is hermetically closed by a frame 8, a base 12, and a cover 15. Reference numeral 16 denotes a lead connected to the fixed electrode 13, and 17 denotes a lead connected to the movable electrode 11. Sensor outputs are output from both leads 16 and 17.

When vibration (or acceleration) is applied to the vibration sensor 2, the beam 9 is bent and the mass 10
Vibrates in the thickness direction (the direction of the arrow).
The distance between the electrodes 1 and 13 changes, and the capacitance between the electrodes 11 and 13 changes. Therefore, by taking out this capacitance change ΔC from the leads 16 and 17 as a sensor output, mechanical vibration can be converted into an electric signal.

FIG. 1 shows a vibration sensor 1 using the vibration sensor 2.
The schematic configuration of is shown. Reference numeral 3 denotes a signal processing circuit which takes in a sensor output output from the vibration sensor 2 and takes out a vibration waveform from the sensor output. The signal processing circuit 3 holds, for example, seismic wave data corresponding to the geography and characteristics of the area by a memory or an IC card, and compares the vibration waveform obtained from the sensor output of the vibration sensor 2 with the seismic wave data. By analyzing the vibration waveform, it is determined whether the detected vibration is an earthquake or a non-earthquake vibration. If it is determined that the detected earthquake is an earthquake, an earthquake output is output to the outside.

The self-diagnosis circuit 4 for detecting a failure of the vibration sensor 2 includes a booster circuit 5 and a sensor failure detection circuit 6. The booster circuit 5 can apply a high voltage of several levels between the electrodes 11 and 13 of the vibration sensor 2 through the leads 16 and 17, and the sensor failure detection circuit 6 can detect an electrode when a high voltage for diagnosis is applied. The change ΔC in the inter-capacity is read from the sensor output, and it is determined whether or not the change in the capacity ΔC is a normal capacity change. If it is determined that the capacity is abnormal, a failure output is output to the outside.

FIG. 3 shows a change in capacitance ΔC when a voltage is applied between the booster circuit 5 and the electrodes 11 and 13 of the vibration sensor 2. As shown in FIG. 3, the electrodes 11, 1
When a voltage V equal to or higher than a fixed voltage (Vs) is applied between the electrodes 3 and 3, a force due to an electric field acts between the electrodes 11 and 13 and the electrodes 11 and 13
The distance between the electrodes 11 and 13 changes. Accordingly, as shown in FIG. 4A, when two levels of high voltage are continuously applied between the electrodes 11 and 13 from the booster circuit 5, the solid line α in FIG. As described above, the inter-electrode capacitance changes greatly. However, if the beam 9 of the vibration sensor 2 is broken and becomes difficult to move,
Even if a high voltage is applied between the electrodes 1 and 13, the distance between the electrodes 11 and 13 is hardly changed, and the capacitance change ΔC is also shown by the broken line β in FIG.
As shown by, the level is abnormal compared to the normal state. Therefore, the state of the capacitance change ΔC is determined by the sensor failure detection circuit 6.
Thus, it is possible to determine whether the vibration sensor 2 is normal or abnormal.

The self-diagnosis operation by the self-diagnosis circuit 4 may be performed, for example, immediately after the power of the seismic sensor 1 is turned on. May be automatically performed once, thereby preventing the seismic sensor 1 from malfunctioning. In addition, the self-diagnosis circuit 4 can be used to sort non-defective and non-defective products of the seismic sensor 1 immediately after manufacturing the seismic sensor 1 or at the time of shipping the seismic sensor 1. The spread of damage can be prevented.

When the self-diagnosis circuit 4 detects a failure of the vibration sensor 1, the failure of the vibration sensor 1 can be notified to the outside by an alarm or the like. Or, seismic sensor 1
Is provided in a gas meter or the like, the self-diagnosis circuit 4
When a failure output is output from the controller, the solenoid valve for gas supply can be automatically closed.

[0017]

According to the present invention, the presence or absence of a failure can be inspected without applying mechanical vibration to the seismic sensor, and self-diagnosis can be easily performed. Therefore,
Even if a structurally weak but sensitive vibration sensor is used, a highly reliable seismic sensor can be manufactured, and damage caused by a failure of the seismic sensor can be prevented. Further, by performing self-diagnosis periodically, it is possible to predict the occurrence of a failure. Further, the product test at the time of the improved shipment can be easily performed, and the defective product of the seismic sensor can be easily and inexpensively checked, thereby preventing the spread of the earthquake damage due to the shipment of the defective product.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a seismic sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a specific structure of the vibration sensor.

FIG. 3 is a diagram showing a relationship between an applied voltage between electrodes and a change amount of inter-electrode capacitance in the vibration sensor of the above.

FIG. 4A is a diagram showing a waveform of a diagnostic voltage applied between electrodes by a self-diagnosis circuit, and FIG. 4B is a diagram showing a normal and abnormal inter-electrode capacitance generated in response to the applied voltage; It is a figure showing a change.

FIG. 5 is a block diagram showing a schematic configuration of a conventional seismic device.

[Explanation of symbols]

 2 Vibration sensor 3 Signal processing circuit 4 Self-diagnosis circuit

Claims (1)

(57) [Claims] 1. A capacitance change type vibration sensor which detects vibration and outputs it as a change in capacitance between electrodes; a signal processing means for extracting a vibration waveform from an output of the vibration sensor to determine occurrence of an earthquake; A self-diagnosis device comprising: self-diagnosis means for applying a plurality of different levels of voltage between the electrodes to determine whether a failure has occurred based on a change in capacitance output from a vibration sensor.