JP4268104B2 - Inclination correction apparatus and inclination correction method - Google Patents

Description

  The present invention relates to a tilt correction device provided in a seismometer or the like and a tilt correction method using the tilt correction device.

Conventionally, seismometers are known that are buried in the ground or on the seabed to detect earthquakes. Such a seismometer is provided with a pendulum supported in a reciprocating manner by a spring at a neutral position. When an earthquake occurs and acceleration is applied to the pendulum, the amount of the deviation is reduced when the pendulum deviates from the neutral position. Vibration data is acquired by detecting the amount of change in capacitance. Accordingly, accurate vibration data cannot be obtained unless the pendulum is accurately adjusted to the neutral position. Therefore, when using the seismometer, tilt correction for adjusting the pendulum to the neutral position is performed (see, for example, Patent Document 1).
Among seismometers, horizontal pendulums with a low natural frequency have a high sensitivity to tilt, and if they are not neutral, the pendulum will fall in the tilt direction of the case body containing the pendulum and function as a pendulum. I can't. Therefore, when the natural frequency of the pendulum is low, it is indispensable to level the case body.

Specifically, the amount of static displacement of the pendulum is expressed by the following equation as a function of the natural frequency of the pendulum and the tilt angle of the case body.
x = g · sin θ / (2πf) ²
x: Static displacement of the pendulum (cm)
g: Gravity acceleration (980cm / s ² )
θ: Angle of inclination of case body relative to horizontal plane (degrees)
f: Pendulum natural frequency (Hz)

According to this equation, for example, when the natural frequency of the pendulum is 1 Hz, the pendulum will deviate from the neutral point by 4.3 mm even if the case body is inclined only once. Usually, the movable range of the pendulum in a vibration detector used for microearthquake observation is about ± 2 to 3 mm, and in order to ensure the maximum movable range of the pendulum of such a vibration detector, particularly low natural vibration In a pendulum having a number, tilt correction is necessary so that the tilt angle is 0 degree.
In order to correct the inclination of the seismometer, the vibration waveform of the pendulum is recorded on a recording sheet by a pen recorder or the like, and the operator confirms a portion having a large amplitude among the recorded vibration waveforms. Then, the seismometer is corrected to the posture when the amplitude of the vibration waveform is increased by the operation of the operator.
JP-A-10-73669

  However, in the conventional tilt correction of the seismometer, the operator has to correct the attitude of the seismometer after confirming the recording paper, so that there is a problem that the tilt correction takes time. In addition, since the operator misreads the recording paper or there is an error in reading the recording paper by the operator, the tilt correction may not be performed accurately.

  Accordingly, the present invention has been made to solve the above-described problem, and an object thereof is to provide a tilt correction device capable of performing tilt correction easily and accurately without being affected by human factors. To do.

In order to solve the above problems, the invention according to claim 1 includes a permanent magnet and a coil disposed in a magnetic field formed by the permanent magnet, and one of the permanent magnet and the coil. Is fixed in the case body, and the other is attached to a pendulum that is elastically supported so that it can vibrate in the case body, and a voltage corresponding to the magnitude of the vibration is generated at both ends of the coil by the vibration of the pendulum. An inclination correction apparatus for correcting the inclination of a vibration detector for detecting vibration, comprising a driving means for changing an inclination angle of the case body with respect to a horizontal plane, and an amplifier for amplifying a voltage generated in the coil. A resonance circuit section that feeds back the voltage to the input of the amplifier, a determination means that determines whether or not the voltage value of the voltage amplified by the resonance circuit section exceeds a predetermined value, and the determination means , When the voltage value is determined to exceed a predetermined value, characterized in that it comprises a drive control means for stopping the driving of the driving means.
Here, the predetermined value used by the judging means for judging the magnitude of the voltage value is a threshold value arbitrarily set by the user, which is sufficiently larger than the noise of the voltage generated in the coil, and is applied to the coil when the pendulum freely vibrates. It is preferable to set a value smaller than the generated voltage value.

  According to a second aspect of the present invention, in the tilt correction apparatus according to the first aspect, the apparatus includes a noise removing unit that removes a noise component of the voltage amplified by the resonance circuit unit.

  Invention of Claim 3 is the inclination correction method using the inclination correction apparatus of Claim 1 or 2, Comprising: The inclination which drives the said drive means and changes the inclination angle with respect to the horizontal surface of the said case body A resonance step of amplifying a voltage generated in the coil by the amplifier by the resonance circuit unit and feeding back the amplified voltage to an input of the amplifier; and the amplification by the determination unit by the resonance circuit unit A determination step for determining whether or not the measured voltage value exceeds a predetermined value; and when the determination means determines that the voltage value exceeds a predetermined value, the driving control means drives the driving means. And a drive stop step for stopping the operation.

  According to the first aspect of the present invention, when the driving means is driven to change the inclination angle of the case body with respect to the horizontal plane, the pendulum elastically supported in the case body vibrates. When the pendulum vibrates, the magnetic field formed by the permanent magnet and the coil move relative to each other to generate a voltage at both ends of the coil. The voltage generated in the coil is amplified by the amplifier, and the amplified voltage is fed back to the input of the amplifier by the resonance circuit unit. And it is judged by the judgment means whether the voltage value of the voltage amplified by the resonance circuit part exceeds a predetermined value. Here, when the determination means determines that the voltage value exceeds the predetermined value, the drive control means stops the drive of the drive means, and the posture of the case body is determined.

  In other words, seismometers can vibrate freely when the pendulum is in the neutral position, and the amplitude increases during free vibration, so the voltage generated in the coil is also greatest when free vibration occurs. . On the other hand, when the coil is in contact with the permanent magnet and the pendulum does not vibrate freely, the amplitude is almost zero, so that the voltage generated in the coil is extremely small.

By utilizing this principle and amplifying and resonating the voltage generated in the coil by the resonance circuit unit, the difference in voltage value when the pendulum is not freely vibrating can be further increased. It becomes possible to grasp more clearly whether or not the vibration is free. Then, if this predetermined value is set sufficiently larger than the voltage value output as noise and smaller than the voltage value of the voltage generated in the coil when the pendulum is free vibrating, the drive control means The tilt of the case body can be stopped while the pendulum is freely vibrating.
Therefore, since the inclination correction device automatically corrects the inclination of the case body, the inclination correction can be performed easily and accurately without being affected by human factors.

According to the second aspect of the present invention, the noise component of the voltage amplified by the resonance circuit unit can be removed by providing the noise removing means.
Accordingly, since the predetermined value can be set lower, it is possible to easily determine whether or not the pendulum vibrates even if it has a minute vibration, so it is necessary to increase the detection accuracy more than necessary. Disappear.

  According to the invention described in claim 3, in the tilting step, the pendulum elastically supported in the case body vibrates by driving the driving means to change the tilt angle of the case body with respect to the horizontal plane. When the pendulum vibrates, the magnetic field formed by the permanent magnet and the coil move relative to each other to generate a voltage at both ends of the coil. Next, in the resonance step, the voltage generated in the coil is amplified by the amplifier, and the amplified voltage is fed back to the input of the amplifier by the resonance circuit unit. Next, in the determination step, it is determined by the determination means whether or not the voltage value of the voltage amplified by the resonance circuit unit exceeds a predetermined value. In the drive stop step, when the determination means determines that the voltage value exceeds the predetermined value, the drive control means stops the drive of the drive means and determines the posture of the case body.

  In other words, seismometers can vibrate freely when the pendulum is in the neutral position, and the amplitude increases during free vibration, so the voltage generated in the coil is also greatest when free vibration occurs. . On the other hand, when the coil is in contact with the permanent magnet and the pendulum does not vibrate freely, the amplitude is almost zero, so that the voltage generated in the coil is extremely small.

By utilizing this principle and amplifying and resonating the voltage generated in the coil by the resonance circuit unit, the difference in voltage value when the pendulum is not freely vibrating can be further increased. It becomes possible to grasp more clearly whether or not the vibration is free. Then, if this predetermined value is set sufficiently larger than the voltage value output as noise and smaller than the voltage value of the voltage generated in the coil when the pendulum is free vibrating, the drive control means The tilt of the case body can be stopped while the pendulum is freely vibrating.
Therefore, since the inclination correction device automatically corrects the inclination of the case body, the inclination correction can be performed easily and accurately without being affected by human factors.

  The best mode of an inclination correction apparatus according to the present invention will be described below in detail with reference to the drawings. In the present embodiment, a tilt correction device provided in a vibration detector that detects seismic vibration in a seismometer will be described as an example.

<Overall configuration of vibration detector>
As shown in FIGS. 1 and 2, the vibration detector 2 provided with the tilt correction device 1 is formed by a case body 21, a permanent magnet 22 fixed to the inner side wall of the case body 21, and the permanent magnet 22. A coil 23 disposed in the magnetic field, and a pendulum 25 attached to one end of the coil 23 and elastically supported by a leaf spring 24 as an elastic member so as to be vibrated in the case body 21. Yes.

  The case body 21 is formed in a substantially cubic shape, and its upper end is rotatably connected to a protective case 26 that protects the vibration detector 2. Further, the lower end of the case body 21 is connected to an attitude control motor 11 (described later) provided at the bottom of the protective case 26, and by driving the attitude control motor 11, the upper end of the case body 21 is moved. The case body 21 can be tilted with respect to a horizontal plane by being rotated as a rotation center.

  An annular magnetic gap 22 a into which the coil 23 is inserted is formed in the permanent magnet 22, so that the coil 23 can be disposed in the magnetic field of the permanent magnet 22.

  The coil 23 is inserted into the magnetic gap 22 a of the permanent magnet 22, and the other end is attached to the pendulum 25. That is, the coil 23 vibrates with the vibration of the pendulum 25. The coil 23 is electrically connected to a resonance circuit unit 13 (described later). That is, when the coil 23 moves in the magnetic field of the permanent magnet 22, the voltage generated at both ends of the coil 23 can be transmitted to the resonance circuit unit 13.

  The pendulum 25 has a predetermined mass, and is attached to the case body 21 via the leaf spring 24. The pendulum 25 can vibrate in the plate thickness direction of the leaf spring 24 in the case body 21 when the case body 21 is inclined.

<Overall configuration of tilt correction device>
As shown in FIGS. 1 and 2, the inclination correction device 1 that corrects the inclination of the vibration detector 2 includes an attitude control motor 11 as a driving unit that changes an inclination angle of the case body 21 with respect to the horizontal plane, and an attitude control motor 11. The motor control circuit unit 12 as a drive control means for controlling the driving of the case body 21 and the amplifier 131 (described later) for amplifying the voltage generated in the coil 23 are provided. A resonance circuit unit 13 that feeds back the amplified voltage to the input of the amplifier 131, and a comparator 14 that determines whether the voltage value of the voltage amplified by the resonance circuit unit 13 exceeds a predetermined value. I have.

  The attitude control motor 11 is installed on the bottom surface of the protective case 26, and the case body 21 is inclined by rotating the lower end portion of the case body 21 around the upper end portion of the case body 21 by a drive mechanism (not shown). It becomes a drive source.

  The motor control circuit unit 12 is electrically connected to the attitude control motor 11, and controls the driving of the attitude control motor 12 by transmitting electric signals such as driving and stopping to the attitude control motor 11. Further, the motor control circuit unit 12 transmits a stop signal to the attitude control motor 11 when the comparator 14 determines that the voltage value of the voltage amplified by the resonance circuit unit 13 exceeds a predetermined value. Stop driving.

As shown in FIG. 3, the resonance circuit unit 13 is configured to input the voltage generated in the coil 23 to the amplifier 131 to amplify the voltage and feed back the output to the input of the amplifier 131. That is, the amplified voltage can be resonated by inputting it again to the amplifier 131. Accordingly, the input voltage is greatly amplified and output as a large vibration waveform.
The resonance circuit unit 13 is provided with a relay 132 before the input of the amplifier 131. By switching the relay 132, the direction of current flow can be changed. Specifically, as shown in FIG. 3, when the relay 132 is connected to the attitude control mode a, the voltage generated in the coil 23 is output to the amplifier 131, and when the relay 132 is connected to the observation mode b, the voltage is generated in the coil 23. The obtained voltage is output to a main controller (not shown) of the seismometer that acquires vibration data, and the earthquake is measured.

  When the comparator 14 sets a predetermined value of the voltage value in advance, when the voltage value of the voltage input from the resonance circuit unit 13 exceeds the predetermined value, the motor control circuit unit 12 sends the attitude control motor 11. It is configured to transmit an electric signal for stopping the driving of. Therefore, when the voltage value of the voltage transmitted from the resonance circuit unit 13 is smaller than the predetermined value, the comparator 14 does not transmit an electric signal to the motor control circuit unit 12 and the driving of the attitude control motor 11 is stopped. Never do.

<Inclination correction method>
Next, the inclination correction method of the vibration detector 2 by the inclination correction apparatus 1 will be described using the flowchart of FIG.
As shown in FIG. 1, when the horizontal level of the case body 21 is not within the allowable range, the coil 23 comes into contact with a stopper (not shown) and cannot freely vibrate. The output waveform from T1 outputs a minute noise voltage waveform that is the pendulum immobilization range of FIG. In this state, when the tilt correction of the vibration detector 2 is performed, the relay 132 is set to the attitude control mode a, the attitude control motor 11 is driven by the motor control circuit unit 12, and the case body 21 is set. The case body 21 is tilted by gradually changing the tilt angle with respect to the horizontal plane (step S1: tilt step).

By tilting the case body 21, the pendulum 25 tilts, but the pendulum 25 vibrates due to the elastic force of the leaf spring 24 that attempts to return the pendulum 25 to its original position. Due to the vibration of the pendulum 25, a voltage is generated at both ends of the coil 23 and is output to the resonance circuit unit 13. In the resonance circuit unit 13, the input voltage is amplified by the amplifier 131, and the amplified voltage is fed back to the input of the amplifier 131 to resonate (step S2: resonance step).
Here, when the horizontal level recovers until the case body 21 reaches the pendulum operating range, the pendulum 25 starts to free move away from the stopper, and shakes greatly at the natural frequency of the pendulum 25, as shown in FIG. The output waveform has a larger amplitude than the noise voltage waveform, and generates a large voltage.

Next, the comparator 14 determines whether or not the voltage value amplified by the resonance circuit unit 13 exceeds a predetermined value (step S3: determination step). Here, when the comparator 14 determines that the voltage value exceeds the predetermined value (step S3: YES), the motor control circuit unit 12 stops the driving of the attitude control motor 11 (step S4: driving stop step). ). This state means that the pendulum 25 has reached the neutral position, and is a state where an earthquake can be detected. The relay 132 is switched to the observation mode b, and the earthquake observation can be obtained as an output signal from the terminal T2. .
On the other hand, when the comparator 14 determines that the voltage value does not exceed the predetermined value (step S3: NO), the process returns to step S1 again, and the motor control circuit unit 12 drives the attitude control motor 11 to perform the case body 21. Tilt.

<Effects of Embodiment>
Thus, according to the inclination correction apparatus 1 and the inclination correction method according to the present invention, when the attitude control motor 11 is driven by the motor control circuit unit 12 and the inclination angle of the case body 21 with respect to the horizontal plane is changed, the case body. A pendulum 25 elastically supported by a leaf spring 24 in 21 vibrates. When the pendulum 25 vibrates, the magnetic field formed by the permanent magnet 22 and the coil 23 move relative to each other to generate a voltage at both ends of the coil 23. The voltage generated in the coil 23 is amplified by the amplifier 131, and the amplified voltage is fed back to the input of the amplifier 131 by the resonance circuit unit 13. Then, the comparator 14 determines whether or not the voltage value of the voltage amplified by the resonance circuit unit 13 exceeds a predetermined value. Here, when the comparator 14 determines that the voltage value exceeds the predetermined value, the motor control circuit unit 12 stops the driving of the attitude control motor 11 and the attitude of the case body 21 is determined.

  That is, it can freely vibrate when the coil 23 attached to the pendulum 25 is not in contact with the stopper, that is, when it is in a neutral position as shown in FIG. Since the voltage increases, the voltage generated in the coil 23 is also maximized when free vibration occurs. On the other hand, as shown in FIG. 1, when the coil 23 comes into contact with the permanent magnet 22 and the pendulum 25 does not freely vibrate, the amplitude is almost zero, so the voltage generated in the coil 23 is extremely small. .

By utilizing this principle and amplifying and resonating the voltage generated in the coil 23 by the resonance circuit unit 13, the difference in voltage value when the pendulum 25 is not freely vibrating can be further increased. It becomes possible to grasp more clearly whether or not the pendulum 25 is freely vibrating. If this predetermined value is set sufficiently larger than the voltage value output as noise and smaller than the voltage value of the voltage generated in the coil 23 when the pendulum 25 is free vibrating, the motor control circuit The part 12 can stop the inclination of the case body 21 in a state where the pendulum 25 is freely vibrating.
Therefore, since the inclination correction apparatus 1 automatically corrects the inclination of the case body 21, the inclination correction can be performed easily and accurately without being affected by human factors.

  The present invention is not limited to the above embodiment. For example, a filter as a noise removing unit that removes a noise component of the voltage amplified by the amplifier may be provided between the comparator and the resonance circuit unit. As a result, the predetermined value can be set lower, so that it is possible to easily determine whether or not the pendulum is vibrating freely even if it is oscillating minutely, so the detection accuracy needs to be increased more than necessary. Disappears. In addition, the present invention can be freely changed and improved without departing from the gist of the invention.

It is explanatory drawing before the inclination correction of the vibration detector by the inclination correction apparatus which concerns on this invention. It is explanatory drawing after the inclination correction of the vibration detector by the inclination correction apparatus which concerns on this invention. It is a circuit diagram of the resonance circuit part of the inclination correction apparatus which concerns on this invention. It is a flowchart which shows the flow about the inclination correction method which concerns on this invention. It is a figure which shows the example when the vibration waveform of the pendulum in the inclination correction apparatus which concerns on this invention is amplified by the resonance circuit part.

Explanation of symbols

1 Inclination correction device 11 Attitude control motor (drive means)
12 Motor control circuit (drive control means)
13 Resonant circuit unit 131 Amplifier 14 Comparator (determination means)
2 Vibration detector 21 Case body 22 Permanent magnet 23 Coil 24 Leaf spring 25 Pendulum

Claims (3)

A permanent magnet and a coil disposed in a magnetic field formed by the permanent magnet, wherein one of the permanent magnet and the coil is fixed in the case body, and the other can vibrate in the case body. An inclination correction device that is attached to an elastically supported pendulum and corrects the inclination of a vibration detector that detects vibration by generating a voltage corresponding to the magnitude of vibration at both ends of the coil by vibration of the pendulum. And
Driving means for changing an inclination angle of the case body with respect to a horizontal plane;
A resonance circuit unit having an amplifier for amplifying a voltage generated in the coil, and feeding back the amplified voltage to an input of the amplifier;
Determination means for determining whether or not the voltage value of the voltage amplified by the resonance circuit unit exceeds a predetermined value;
A drive control means for stopping the drive of the drive means when it is determined by the determination means that the voltage value exceeds a predetermined value;
An inclination correction apparatus comprising:   The inclination correction apparatus according to claim 1, further comprising a noise removing unit that removes a noise component of the voltage amplified by the resonance circuit unit. A tilt correction method using the tilt correction device according to claim 1 or 2,
An inclination step of driving the driving means to change an inclination angle of the case body with respect to a horizontal plane;
A resonance step of amplifying a voltage generated in the coil by the amplifier by the resonance circuit unit, and feeding back the amplified voltage to the input of the amplifier;
A determination step of determining whether or not a voltage value amplified by the resonance circuit unit exceeds a predetermined value by the determination unit;
A drive stop step of stopping the drive of the drive means by the drive control means when the determination means determines that the voltage value exceeds a predetermined value;
An inclination correction method comprising:

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