Seismic Sensor

Abstract

The present invention provides a novel seismic sensor as follows: in the recorder function of the seismic sensor, seismic acceleration data before earthquake detection can be obtained, and it can work in a state of reduced power consumption. The seismic sensor switches the action mode of earthquake detection or earthquake acceleration measurement according to the measured acceleration, and has: a simple earthquake detection mode, in which, when the measured acceleration is below a specified first threshold, the simple earthquake detection mode is continued, and the measured acceleration data is not saved; an earthquake detection mode, in which, when the measured acceleration in the simple earthquake detection mode is greater than the first threshold and below a second threshold greater than the first threshold, the earthquake detection mode is continued, and the measured acceleration data is saved; and an earthquake measurement mode, in which, when the measured acceleration in the earthquake detection mode is greater than the second threshold, the earthquake measurement mode is continued, and the acceleration and SI value are measured and saved.

Description

Technical Field

[0001] The present invention relates to a seismic sensor. Background Art

[0002] In the case of a battery-driven device such as a seismic sensor that is installed in a meter box and is used to cut off gas and electricity when an earthquake occurs, it is particularly desirable to reduce standby power. However, although a seismic sensor using an MCU (Micro Controller Unit) can obtain an index value for evaluating the magnitude of an earthquake through calculation processing, the power consumption tends to be higher than that of a conventional mechanical seismic sensor that is powered by vibration.

[0003] As a seismic sensor, a technology has been proposed in the past that performs earthquake detection after switching from a low power consumption mode to a measurement mode, and returns to a low power consumption mode when it is determined that there is no earthquake. The technology improves the detection accuracy by filtering the measured acceleration and removing noise components (for example, Patent Document 1).

[0004] In addition, a seismograph has been proposed that increases the trigger level in coordination with the calculated noise level, thereby accurately distinguishing whether the detected vibration is noise or an earthquake, and setting a threshold for possible delays in earthquake detection. When the noise level exceeds the threshold and persists for a certain period of time, an abnormal alarm unit sounds an alarm to indicate that an abnormality has occurred that prevents the earthquake from being correctly detected, thereby being able to accurately grasp situations in which earthquake detection may be delayed (for example, Patent Document 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-15604

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-108847 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In the seismic sensors used for earthquake measurement as described above, in addition to reducing power consumption and improving the sensitivity of earthquake detection accuracy, the purpose is to study the acceleration before and after an earthquake occurs, and to obtain acceleration data of vibrations before earthquake detection.

[0011] In this regard, it is considered to always acquire acceleration data at fixed intervals before switching to measurement mode after detecting an earthquake, but in this case, it is difficult to ensure that the seismic sensor can operate for a long time such as 5 or 10 years under battery operation. Alternatively, there is a disadvantage that the user may have to replace the battery more frequently, which is time-consuming.

[0012] Therefore, in view of the above-mentioned problems, the ultimate object of the present invention is to provide a seismic sensor having a recorder function capable of acquiring vibration acceleration data even before an earthquake is detected and capable of reducing power consumption as much as possible.

[0013] Here, the seismic sensor having the recorder function as described above in the present invention may be only a seismic sensor.

[0014] Means for solving problems

[0015] The seismic sensor of the present invention for solving the above-mentioned problems switches the operation mode related to earthquake detection or earthquake acceleration measurement according to the measured acceleration, wherein:

[0016] The seismic sensor has:

[0017] A simple earthquake detection mode, when the measured acceleration is below a predetermined first threshold value, the simple earthquake detection mode is continued and the measured acceleration data is not saved;

[0018] earthquake detection mode, when the acceleration measured in the simple earthquake detection mode is greater than the first threshold value and less than a second threshold value, continuing in the earthquake detection mode and saving the measured acceleration data, where the second threshold value is greater than the first threshold value; and

[0019] In the earthquake measurement mode, when the acceleration measured in the earthquake detection mode is greater than the second threshold value, the earthquake measurement mode is continued, and the acceleration and SI (Spectrum Intensity) value are measured and saved.

[0020] According to the present invention, even in the simple earthquake detection mode in which earthquake acceleration storage processing is not performed, acceleration is measured, so earthquake detection can be performed with low power consumption. In addition, if the acceleration measured in the simple earthquake detection mode is above the specified first threshold value, it is switched to the earthquake detection mode, and the acceleration is measured and stored, so that the acceleration data before the earthquake occurs can be recorded. In addition, if the acceleration measured in the earthquake detection mode is above the specified second threshold value, it is switched to the earthquake measurement mode, and in addition to the acceleration, the SI value is measured and stored, so that when an acceleration is generated that is judged to be an earthquake, an indicator of the impact of seismic activity on the structure can be recorded. That is, according to the present invention, acceleration information before an earthquake occurs can be obtained with low power consumption.

[0021] In addition, in the present invention, the following seismic sensor can also be used, characterized in that the seismic sensor has an information processing device and an acceleration sensor, in the simple earthquake detection mode, the information processing device is in a disconnected state and the acceleration sensor is in an on state, and in the earthquake detection mode and the earthquake measurement mode, the information processing device is in an intermittent drive state and the acceleration sensor is in an on state. Thus, in the simple earthquake detection mode, the information processing device is in a disconnected state, so that power consumption can be reduced more reliably. In addition, the low-power acceleration sensor is in an on state, so that microvibrations before an earthquake can be linked to earthquake detection.

[0022] In addition, in the present invention, the following seismic sensor can also be used, characterized in that the seismic sensor further includes: a storage unit for storing the acceleration data, the periods of the earthquake detection mode and the earthquake measurement mode are divided into a predetermined acceleration data acquisition period, and each time the acceleration data acquisition period passes, the acceleration data measured by the acceleration sensor is temporarily stored in the memory in the information processing device, and after the earthquake measurement mode ends, the acceleration data temporarily stored in the memory in the information processing device is stored in the storage unit. Thus, the seismic sensor can obtain acceleration data with an earthquake as a trigger condition.

[0023] In addition, in the present invention, the following seismic sensor can also be used, characterized in that the acceleration data acquisition period is 20 seconds, and after the seismic measurement mode ends, the acceleration data stored in the storage unit is the acceleration data acquired during the entire data acquisition period in the seismic measurement mode, and the acceleration data acquired during the data acquisition period immediately before the earthquake in the seismic detection mode. Thus, in addition to the earthquake occurrence process, the acceleration data immediately before the earthquake can also be recorded.

[0024] In addition, in the present invention, the following seismic sensor can also be used, characterized in that after the acceleration data acquired during the entire data acquisition period in the seismic measurement mode is saved, the simple earthquake detection mode is switched again. In this way, the acceleration data when an earthquake occurs can be acquired with high reliability, and it is beneficial to reduce power consumption. In addition, once the earthquake stops, the acceleration measurement can be continued again with low power consumption.

[0025] Effects of the Invention

[0026] In the seismic sensor, data acquisition of acceleration of vibration before earthquake detection can be performed by the recorder function, and power consumption when measuring acceleration before earthquake detection can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram of the structure of a device that is a prerequisite for a seismic sensor.

[0028] FIG. 2( a ) and FIG. 2( b ) are diagrams for explaining the actual conventional operation mode of the accelerometer and the seismic sensor.

[0029] Figure 3 This is a diagram for explaining a situation in which the seismic sensor is operated in an earthquake detection mode before the occurrence of an earthquake is detected.

[0030] Figure 4 This is a processing flow chart of the action mode of the seismic sensor.

[0031] Figure 5 This is a diagram for explaining the operation mode of the seismic sensor.

[0032] FIG. 6( a ) and FIG. 6( b ) are diagrams for explaining the acquisition of acceleration data by the seismic sensor.

[0033] Description of Reference Numerals

[0034] 1: Seismic sensor

[0035] 11: Acceleration sensor

[0036] 12: MCU (Micro Controller Unit)

[0037] 13: Storage

[0038] 14: Output section

[0039] 15: Input section DETAILED DESCRIPTION

[0040] [Application Examples]

[0041] In this application example, a case where a recorder function for acquiring acceleration data and a simple earthquake detection mode, which is an operation mode for reducing power consumption, are applied to a seismic sensor is described. Figure 1 As shown, the seismic sensor of this application example comprises: an acceleration sensor 11; an MCU 12, which detects the occurrence of an earthquake and calculates the magnitude of an earthquake based on the acceleration measured by the acceleration sensor 11; a storage unit 13, which stores the measured acceleration and threshold values ​​for earthquake judgment; an output unit 14, which outputs information indicating the occurrence and magnitude of an earthquake; and an input unit 15, which is an input terminal of the MCU 12. Moreover, according to the magnitude of the measured acceleration, the action mode related to earthquake detection and earthquake acceleration measurement is switched. In more detail, as Figure 5 As shown, the operation modes are divided into three types, and the system operates in any one of the simple earthquake detection mode, the earthquake detection mode, and the earthquake measurement mode.

[0042] In the simple earthquake detection mode, acceleration is measured, and the measured acceleration data is not saved. When the measured acceleration is below a predetermined first threshold value, the simple earthquake detection mode continues to operate.

[0043] In the earthquake detection mode, the acceleration is measured and the measured acceleration data is saved. When the acceleration is greater than a first threshold value and less than a second threshold value, the earthquake detection mode continues to work. Here, the second threshold value is greater than the first threshold value.

[0044] In the earthquake measurement mode, the acceleration and SI value are measured and the measured acceleration and SI value are stored. In the earthquake detection mode, when the acceleration measured is greater than the second threshold value, the earthquake measurement mode continues to operate for a predetermined time.

[0045] As described above, the seismic sensor 1 includes the MCU 12 and the acceleration sensor 11. In the simple earthquake detection mode, the MCU 12 is turned on and the acceleration sensor 11 is turned off. In the earthquake detection mode and the earthquake measurement mode, the MCU 12 and the acceleration sensor 11 are both turned on.

[0046] As shown in Figure 6, acceleration data is temporarily saved at fixed intervals of every 20 seconds, and the period for saving data with an earthquake as a trigger condition is 120 seconds after an earthquake is detected in the earthquake measurement mode, and 20 seconds before an earthquake occurs in the earthquake detection mode. After saving 120 seconds of measurement data in the earthquake measurement mode, switch to the simple earthquake detection mode.

[0047] [Example 1]

[0048] The following is an explanation of the seismic sensor of the embodiment of the present invention using the accompanying drawings. In addition, in the following embodiment, an example of applying the present invention to a module-type seismic sensor is explained, but the present invention can also be applied to other seismic sensors such as a substrate-type seismic sensor. The embodiment shown below is an example of a module-type seismic sensor, and the module-type seismic sensor of the present invention is not limited to the following structure.

[0049] <Device Structure>

[0050] Figure 1 1 is a diagram showing a device configuration as a prerequisite of the seismic sensor of the present embodiment. The seismic sensor 1 includes an acceleration sensor 11 , an MCU 12 , a storage unit 13 , an output unit 14 , and an input unit 15 .

[0051] The acceleration sensor 11 is, for example, an acceleration sensor using a piezoelectric element or an acceleration sensor that detects electrostatic capacitance between electrodes. The acceleration measured (also referred to as “sampled”) by the acceleration sensor 11 is output to the MCU 12 .

[0052] MCU12 is, for example, a general integrated circuit, and acquires the acceleration measured by the acceleration sensor 11 at a predetermined period, and detects the occurrence of an earthquake or calculates an index value representing the magnitude of an earthquake based on the acceleration. In addition, MCU12 operates in different forms such as an active mode or a sleep mode depending on the situation. Sleep mode refers to an operation in which MCU12 operates in a manner that limits functions by stopping the execution of commands or stopping the supply of clocks while receiving an interrupt, thereby reducing power consumption compared to the active mode. In the active mode, MCU12 determines whether the detected vibration is an earthquake or noise or calculates an index value representing the magnitude of an earthquake.

[0053] The storage unit 13 is a temporary storage unit such as RAM (Random Access Memory) or a non-volatile memory such as EPROM (Erasable Programmable Read Only Memory), for example, to maintain the measured acceleration, the threshold value for earthquake judgment, etc. In addition, the storage unit 13 may also be a memory having an acceleration sensor 11 and MCU12 built in. In addition, the output unit 14 is, for example, an output terminal of the MCU12. For example, when it is determined that an earthquake has occurred, the MCU12 outputs information indicating the occurrence and scale of the earthquake to other devices via the output unit 14. The output unit 14 may also have a communication function. In addition, the input unit 15 is an input terminal of the MCU12. It is also possible to adopt the following method, that is, the MCU12 receives, for example, the operation of a switch not shown in the figure, the input of instructions from other devices, etc. via the input unit 15.

[0054] A high-pass filter (not shown) may be provided between the acceleration sensor 11 and the MCU 12 to remove the gravity component. Alternatively, the MCU 12 may convert the acceleration measured by the acceleration sensor 11 into an absolute value of the acceleration based on a predetermined offset and process the acceleration.

[0055] FIG. 2 is a diagram for explaining the actual existing operation of the accelerometer and the seismic sensor 1. FIG. 2(a) shows an overview of the operation of the accelerometer. A general accelerometer acquires acceleration data using a start signal or the like as a trigger condition. As the start signal, (1) a signal generated by clicking a start button, (2) a signal output when a predetermined time is reached by setting a timer, (3) a signal output when an acceleration signal above a predetermined value is detected, (4) a signal generated by a combination of the above, etc. are considered. In particular, when using (1) a signal generated by clicking a start button or (2) a signal output when a predetermined time is reached by setting a timer, the acquisition of acceleration data is started regardless of the occurrence of an earthquake, so the amount of data acquired becomes huge. Next, FIG. 2(b) shows an overview of the operation of the existing seismic sensor 1. The existing seismic sensor 1 acquires acceleration data using the occurrence of an earthquake as a trigger condition. In this case, the MCU 12 does not work before the earthquake occurs, so it is not possible to acquire acceleration data of the vibration before the earthquake detection. In addition, if the threshold for detecting the occurrence of an earthquake is too high, the low-acceleration P wave that arrives before the S wave when an earthquake occurs cannot be detected. In addition, if the threshold is too low, noise such as daily vibrations may be mistakenly detected as an earthquake.

[0056] As a mode of operation of the seismic sensor 1 , it is conceivable to operate the seismic sensor 1 in an earthquake detection mode for detecting acceleration with less power consumption before the acceleration sensor 11 detects the occurrence of an earthquake. Figure 3 1 is a diagram for explaining the operation of the seismic sensor 1 in the earthquake detection mode before the occurrence of an earthquake is detected. Figure 3 In the earthquake detection mode, the acceleration sensor 11 is always connected, and the acquired acceleration data is temporarily stored in the RAM (not shown) in the acceleration sensor 11. In the earthquake detection mode, the MCU12 receives acceleration data from the acceleration sensor 11. The following process is repeated: the MCU12 is kept in the on state for 10msec (milliseconds) and in the off state for 320msec. That is, the MCU12 acquires acceleration data from the RAM in the acceleration sensor 11 at a ratio of being turned on for 10msec every 330msec. 20 seconds of the acquired acceleration data are stored in the RAM (not shown) of the MCU12. If it exceeds 20 seconds, it will be deleted, and the storage of 20 seconds of acceleration data will start again.

[0057] In the earthquake measurement mode, the MCU 12 is turned on at the same timing as in the earthquake detection mode, and receives acceleration data from the RAM of the acceleration sensor 11 and stores it in the RAM of the MCU 12. At this time, the SI value shown in the mathematical formula (1) is also calculated simultaneously.

[0058]

Mathematical formula 1

[0059]

[0060] The SI value is an index of the destructive force of earthquake activity, which is obtained by averaging the integral values ​​of the velocity response spectrum between 0.1 seconds and 2.5 seconds, which is the natural period of a relatively rigid structure. v is the velocity response spectrum, T is the period, and h is the attenuation constant. Figure 3 As shown in FIG. 1 , the period during which the MCU 12 is in the on state is longer than in the earthquake detection mode, and the period during which the MCU 12 is in the off state is shorter than in the earthquake detection mode. Therefore, the power consumption in the earthquake measurement mode is greater than that in the earthquake detection mode.

[0061] In addition, in this case, a large amount of data is acquired before the occurrence of an earthquake is detected by the acceleration sensor 11, which causes the working time of the MCU 12 to be prolonged, thereby increasing power consumption, which is not efficient.

[0062] Based on the above problems, the seismic sensor 1 in this embodiment is set as a seismic sensor with the following recorder function, which works in a low-power mode before earthquake detection and can obtain data on the acceleration of vibration before earthquake detection. Here, the seismic sensor with the recorder function is also defined as equivalent to the seismic sensor 1.

[0063] Figure 4 This is a processing flow chart of the operation mode of the seismic sensor 1 in this embodiment. This process is performed by the MCU 12 executing the program stored in the storage unit 13 of the seismic sensor 1. The seismic sensor 1 switches the mode of earthquake detection and earthquake acceleration measurement according to the magnitude of the measured acceleration. The mode is divided into 3 types, and works in any one of the simple earthquake detection mode, earthquake detection mode, or earthquake measurement mode. If this process is executed, first, the seismic sensor 1 works in the simple earthquake detection mode ( Figure 4 : S101). Next, in the acceleration sensor 11, acceleration data is acquired in the simple earthquake detection mode (S102). In the simple earthquake detection mode, acceleration data is not stored.

[0064] The acceleration data acquired in the process of S102 is compared with a predetermined first threshold value (acceleration threshold value) pre-set in the seismic sensor 1 (S103). When the acceleration acquired in the simple earthquake detection mode is less than the first threshold value (S103: No), the simple earthquake detection mode is continued. On the other hand, when the acceleration acquired in the simple earthquake detection mode is greater than the first threshold value (S103: Yes), the seismic sensor 1 is switched to the earthquake detection mode (S104).

[0065] After the seismic sensor 1 switches to the earthquake detection mode, it acquires and saves acceleration data (S105). For the acquired acceleration, a comparison is performed with a predetermined second threshold value (acceleration threshold value) pre-set in the seismic sensor 1 (S106). Here, the second threshold value is greater than the first threshold value. When the acceleration acquired in the earthquake detection mode is less than the second threshold value (S106: No), return to S103. In S103, the comparison with the first threshold value (acceleration threshold value) is performed again (S103). When the acceleration acquired in S105 last time is less than the first threshold value (S103: No), switch to the simple earthquake detection mode. On the other hand, when the acceleration acquired in S105 last time is greater than the first threshold value (S103: Yes), continue the earthquake detection mode (S104). On the other hand, when the acceleration acquired in the earthquake detection mode is greater than the second threshold value (S106: Yes), the seismic sensor 1 switches to the earthquake measurement mode (S107). Here, the earthquake measurement mode is equivalent to the measurement mode.

[0066] After the seismic sensor 1 switches to the seismic measurement mode, acceleration data acquisition is performed (S108). The SI value is calculated based on the acquired acceleration (S109). In addition, a judgment is made as to whether 120 seconds have passed since the switch to the seismic measurement mode (S111). If 120 seconds have not passed (S111: No), the process returns to S108 and is repeatedly executed starting from the acceleration data acquisition. If 120 seconds have passed (S111: Yes), 120 seconds of data in the seismic measurement mode and 20 seconds of data in the seismic detection mode are saved (S112), and the simple seismic detection mode is switched again.

[0067] Figure 5 1 is a diagram for explaining the operation mode of the earthquake sensor 1 in this embodiment. The switching between the simple earthquake detection mode, the earthquake detection mode, and the earthquake measurement mode is as follows: Figure 4 As shown in the processing flow chart. During the operation of the seismic sensor 1, the acceleration sensor 11 is always in the on state in any mode, and the MCU 12 is in the off state in the simple earthquake detection mode. Conversely, it is in the on state (intermittently on state) in the earthquake detection mode and the earthquake measurement mode.

[0068] Therefore, in the simple earthquake detection mode in which the acceleration sensor 11 is in the on state and the MCU 12 is in the off state, it is most likely to reduce the power consumption of the seismic sensor 1. In addition, if the simple earthquake detection mode is switched to the earthquake detection mode, the MCU 12 is transferred to the on state, so that the earthquake detection mode can be used as a recorder function before the earthquake occurs.

[0069] FIG6 is a diagram for explaining the acquisition of acceleration data of the seismic sensor 1 in the present embodiment. FIG6(a) shows the internal operation mode of the seismic sensor 1. FIG6(b) shows the operation mode of the seismic sensor 1. As shown in FIG6(a), the measurement data of acceleration acquired in the acceleration sensor 11 is temporarily saved to the RAM (not shown) in the MCU 12 at a fixed interval of every 20 seconds. In addition, as shown in FIG6(b), the period for saving the measurement data with the earthquake as the trigger condition is 120 seconds after the earthquake is detected in the earthquake measurement mode, and 20 seconds before the earthquake occurs in the earthquake detection mode. Therefore, in addition to the acceleration data during the earthquake, the seismic sensor 1 can also record the acceleration data before the earthquake occurs. In addition, after the measurement data is saved, the acceleration data other than the 120 seconds after the earthquake is detected in the earthquake measurement mode and the 20 seconds before the earthquake occurs in the earthquake detection mode will be reset.

[0070] In addition, in the following, in order to enable comparison between the constituent elements of the present invention and the structure of the embodiment, the constituent elements of the present invention are described by attaching reference numerals.

[0071] <Invention 1>

[0072] A seismic sensor 1 switches an operation mode related to earthquake detection or earthquake acceleration measurement according to measured acceleration, the seismic sensor 1 comprising:

[0073] A simple earthquake detection mode, when the measured acceleration is below a predetermined first threshold value, the simple earthquake detection mode is continued and the measured acceleration data is not saved;

[0074] earthquake detection mode, when the acceleration measured in the simple earthquake detection mode is greater than the first threshold value and less than a second threshold value, continuing in the earthquake detection mode and saving the measured acceleration data, where the second threshold value is greater than the first threshold value; and

[0075] In the earthquake measurement mode, when the acceleration measured in the earthquake detection mode is greater than the second threshold value, the earthquake measurement mode is continued, and the acceleration and SI value are measured and saved.

Claims

1. A seismic sensor that switches an operation mode related to earthquake detection or earthquake acceleration measurement according to measured acceleration, The seismic sensor has: A simple earthquake detection mode, when the measured acceleration is below a predetermined first threshold, continuing the simple earthquake detection mode and not saving the measured acceleration data; earthquake detection mode, when the acceleration measured in the simple earthquake detection mode is greater than the first threshold value and less than the second threshold value, the earthquake detection mode is continued and the data of the measured acceleration is saved, wherein, The second threshold is greater than the first threshold; as well as seismic measurement mode, when the acceleration measured in the seismic detection mode is greater than the second threshold, continuing the seismic measurement mode, measuring and saving the acceleration, calculating and saving the spectral intensity value, The seismic sensor includes an information processing device and an acceleration sensor. In the simple earthquake detection mode, the information processing device is in an off state and the acceleration sensor is in an on state. In the earthquake detection mode and the earthquake measurement mode, the information processing device is in an intermittent driving state and the acceleration sensor is in an on state, The seismic sensor further includes a storage unit, wherein the storage unit stores the acceleration data. The periods of the earthquake detection mode and the earthquake measurement mode are divided into predetermined acceleration data acquisition periods. During each acceleration data acquisition period, the acceleration data measured by the acceleration sensor is temporarily stored in a memory in the information processing device. After the earthquake measurement mode ends, the acceleration data temporarily stored in the memory in the information processing device is stored in the storage unit. After the earthquake measurement mode ends, the acceleration data stored in the storage unit are the acceleration data acquired during the entire data acquisition period in the earthquake measurement mode and the acceleration data acquired during the data acquisition period immediately before the earthquake in the earthquake detection mode.

2. The seismic sensor according to claim 1, characterized in that: After the acceleration data acquired during the entire data acquisition period in the earthquake measurement mode is saved, the mode is switched to the simple earthquake detection mode again.

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