WO2004046668A1 - Horizontal ground motion detector - Google Patents

Horizontal ground motion detector Download PDF

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Publication number
WO2004046668A1
WO2004046668A1 PCT/JP2002/012550 JP0212550W WO2004046668A1 WO 2004046668 A1 WO2004046668 A1 WO 2004046668A1 JP 0212550 W JP0212550 W JP 0212550W WO 2004046668 A1 WO2004046668 A1 WO 2004046668A1
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WO
WIPO (PCT)
Prior art keywords
horizontal
pendulum
weight
horizontal pendulum
panel
Prior art date
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PCT/JP2002/012550
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French (fr)
Japanese (ja)
Inventor
Yuji Otake
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Japan As Represented By The President Of The University Of Tokyo
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Publication of WO2004046668A1 publication Critical patent/WO2004046668A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/16—Receiving elements for seismic signals; Arrangements or adaptations of receiving elements
    • G01V1/18—Receiving elements, e.g. seismometer, geophone or torque detectors, for localised single point measurements
    • G01V1/181—Geophones
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H1/00—Measuring characteristics of vibrations in solids by using direct conduction to the detector

Definitions

  • the present invention relates to a horizontal ground motion detector used for a seismograph or the like, and particularly to a horizontal ground motion detector capable of performing highly accurate measurement with a simple configuration.
  • Earth observation instruments such as broadband 'high-sensitivity seismometers and superconducting gravimeters, such as STS (speedometer) and CMG (accelerometer), use the internal tomography of the earth to accurately capture the small waveforms of teleseismic earthquakes. It has been used to clarify the internal structure of the earth, and has made a great contribution to recent seismic research. In order to develop such seismic research, high-sensitivity and high-accuracy servo-type seismometers have been developed.
  • seismometers that use a pendulum to create an inertia fixed point and measure the displacement between the vibrating ground and the inertia fixed point to detect vibrations have been used conventionally. I have. In order to increase the sensitivity and bandwidth of such seismographs, and to measure the low-frequency region peculiar to earthquakes, it is necessary to obtain a long natural cycle.
  • one problem is how to obtain a long natural cycle.
  • the weight of the pendulum may be made very heavy.
  • seismographs would become large in size.
  • the inverted pendulum is used to cancel the gravity acting on the weight with the restoring force of the mechanical panel to achieve a weak panel constant.
  • a zero-length panel has been devised, which is used in seismometers of the rugged type and in Lacoste gravimeters.
  • the above-mentioned horizontal high-sensitivity seismometer had the following problems.
  • a small panel constant is obtained by canceling out large forces, slight changes in the elastic constant of the panel due to slight inclination of the ground, installation errors, and temperature and aging are also affected. Enlarge and reduce the difference greatly.
  • the change in the difference results in a change in the panel constant of the entire pendulum, which causes a change in the natural period and gain, and is directly linked to the drift noise of the measured value. Therefore, there was a problem that it was difficult to make adjustments and installation during observation.
  • CMG CMG
  • an object of the present invention is to prevent the generation of drift noise due to a change in the panel constant of the elastic member, and to make adjustments and observations possible even when the period of the pendulum is to be increased. Easy installation Accordingly, it is an object of the present invention to provide a horizontal ground motion detector capable of achieving a high dynamic range and stabilization.
  • the horizontal ground motion detector has a weight portion provided on the distal end side, a base end side supported by a panel panel, and a horizontal swing rocking in a horizontal plane with the base end side as a center.
  • a pendulum, a levitation magnet portion disposed opposite to the horizontal pendulum and magnetically levitating the weight to maintain the swinging direction of the horizontal pendulum in a horizontal plane; and a horizontal magnet of the horizontal pendulum.
  • a measuring unit for measuring a swing angle a calculating unit for calculating a restoration amount of the horizontal pendulum based on a swing angle of the horizontal pendulum by the measuring unit, and a calculation unit based on a calculation result by the calculating unit And a restoring unit for restoring the horizontal pendulum.
  • Fig. 3 is a side view showing the horizontal ground motion detector.
  • Figure 6 is a graph showing the relationship between magnetic field strength, levitation force, and magnet area.
  • FIG. 7 is an explanatory diagram schematically showing the force applied to the weight.
  • Figure 8A shows the relationship between the current to the solenoid coil and the natural period. This is the graph shown.
  • Figure 8B is a graph showing the relationship between the inclination of the base and the natural period.
  • FIG. 1 is a perspective view showing a horizontal high-sensitivity seismometer 10 according to an embodiment of the present invention
  • FIG. 2 is a plan view showing the horizontal high-sensitivity seismograph 10 partially cut away
  • FIG. Figure and Figure 4 are rear views of the horizontal high-sensitivity seismograph 10.
  • arrows XYZ indicate three directions orthogonal to each other, and in particular, arrow XY indicates a horizontal direction, and arrow Z indicates a vertical direction.
  • the horizontal high-sensitivity seismometer 10 is a so-called servo-type seismometer.
  • the servo-type seismometer detects the position of the weight and stops its movement so that the pendulum does not swing even when a large shaking is caused by a large external force. This will enable high dynamic range and stabilization of seismometers.
  • the signal from the feedback circuit to the coil actuator connected to the weight and the output signal of the position detection circuit are used as the vibration detection output. And feedback. It has the characteristic that the attenuation constant and natural period of the pendulum can be varied by compensation using the parameters.
  • the horizontal high-sensitivity seismometer 10 has a base 11 fixed to the measurement position, a horizontal pendulum mechanism 20 mounted on the base 11, a magnetic levitation mechanism 30 and a pendulum restoration mechanism 40. And a control circuit 100 for controlling the pendulum restoring mechanism 40 based on the position of the horizontal pendulum 24.
  • the upper magnets 27 and 28 are formed by alternately arranging narrow N-pole and S-pole magnets (a few mm wide) in an arc centered on the central axis 23a of the X-shaped hinge 23. It is composed of It should be noted that a magnet in which N and S poles are alternately magnetized may be used instead of the band magnet.
  • the magnetic levitation mechanism 30 is provided in a non-contact manner with the frame 31 and the lower magnet portions 32, 33 provided on the frame 31 and opposed to the upper magnet portions 27, 28 described above. Check the swing angle of the horizontal pendulum 24. And a capacitance position detector 34 which emits the capacitance.
  • the capacitance position detector 34 measures the capacitance proportional to the displacement between the target reference mass and the electrode on the detector, and is output as an analog value. You.
  • the maximum resolution of the capacitance position detector 34 is, for example, 0.5 nm.
  • the pendulum restoring mechanism 40 includes a gantry 41, a magnetic panel mechanism 42 supported by the gantry 41, and a feedback mechanism 50.
  • the magnetic panel mechanism 42 has a solenoid docoinole 43 that forms a magnetic field axis along the direction of the arrow Y, and an axial direction that is in the direction of the arrow Y, and the tip of which is in contact with the horizontal pendulum 24. It has a circular bar magnet 4 and 4.
  • the solenoid coil 43 When the solenoid coil 43 is energized by the control circuit 100, it can apply a driving force to the circular bar magnet 44 to change the natural cycle of the horizontal pendulum 24. is there.
  • the driving force of the magnetic panel mechanism 42 is defined as f m ag.
  • the feedback mechanism 50 has a solenoid coil 51 that forms a magnetic field axis along the arrow Y direction, and a tip that contacts the horizontal pendulum 24 with the axial direction as the arrow Y direction. And a circular bar magnet 52 arranged in a row.
  • the solenoid 51 is energized and driven by a feed knock coil drive unit 104, which will be described later, applies a driving force to the circular bar magnet 44 and applies a driving force to the horizontal pendulum 24. It regulates movement.
  • the control circuit 100 is an analog feedback circuit, and as shown in FIG. 5, a preamplifier 101 for amplifying the output from the capacitance position detector 34, and a phase compensator. And a feed knock coil drive section 1 4 4 for driving a feed knock coil 43, and a feed knock coil drive section 1 4 4 for driving the solenoid coil 43.
  • the fact that a long-period pendulum is realized using the magnetic levitation mechanism 30 and the X-shaped hinge 23 will be described in detail. That is, Since the fluctuation of the panel constant of the elastic member used to support the vibrator is determined by the ratio to the elastic constant of the spring, it is weak to reduce the absolute value of the fluctuation of the spring constant. It is preferable to use metal springs. However, the weight supported by the weak metal panel is limited to light ones. Therefore, the weight is supported independently of the panel system to create an asymmetric state, and a weak panel mechanism is added to the weight using metal or another method to create a long-period oscillator. This is required.
  • the horizontal pendulum 24 was supported by the magnetic levitation mechanism 30 and the X-shaped hinge 23 was used as a weak spring mechanism.
  • the X-shaped hinge 23 can be constituted by a weak plate spring, and the period can be increased. It will be possible. Furthermore, when the natural period of the pendulum is fixed, it is expected that the use of a light ⁇ will make the seismograph lighter.
  • the weight of the weight 26 that can be levitated by the permanent magnet is a parameter that determines the natural period of the horizontal pendulum 24.
  • the calculation results of the flying weight by the opposing permanent magnets are described. However, almost the same results can be obtained with the levitation magnets of Ns alternately magnetized.
  • the attractive force F of the opposing magnet is
  • the operating characteristics of the horizontal pendulum 24 are mainly determined by the restoring force fres of the panel of the X-shaped hinge 23.
  • the force of the magnetic panel mechanism 42 is defined as f m ag.
  • a negative force f g s in acting on the weight 26 to cancel the restoring force of the X-shaped hinge 23 due to the gravity f g acts on the weight 26.
  • Fig. 7 schematically shows the relationship between the forces acting on the weight 26.
  • the tilt (rotation component) of the main unit along the Y-Z plane (tilt of the Y axis) with the force in Fig. 7 leads to the shift of the equilibrium point of the horizontal pendulum 24, and this detector In principle distinguishes this component from the external force of horizontal motion Can not.
  • the tilt (rotation component) of the body along the X_Z plane (X-axis tilt) leads to a change in the panel constant.
  • f ext is the external force
  • m is the reference mass
  • ⁇ is the damping coefficient
  • k is the panel constant of the X-shaped hinge 23
  • g is the gravitational acceleration
  • ⁇ is the angle that determines the degree of inversion of the horizontal pendulum
  • 0 is the deflection angle of the horizontal pendulum
  • M gsp is the magnetic charge of the internal rod magnet of the magnetic panel mechanism 42
  • 11 is the number of turns of the solenoid coil 43 of the magnetic panel mechanism 42
  • I is the number of turns.
  • ⁇ is the radius of the solenoid coil 43
  • xd is the displacement of the horizontal oscillator 24.
  • the first term in the parentheses on the right side is the restoring force ⁇ res of the X-shaped hinge 23, and the second term is the inverting force f gs in due to gravity acting on the weight 26 of the horizontal pendulum 24.
  • the term is the force f mag by the magnetic panel mechanism 42.
  • the external force that leads to the noise of the seismometer has a variety of things such as sound and pressure change in addition to the above-mentioned tilt component.
  • the magnetic spring mechanism 42 applies a negative restoring force in the direction opposite to that of the X-shaped hinge 23, and changes the natural period of the horizontal pendulum 24 in the direction to increase.
  • the calculated value is shown by the solid line in Fig. 8A.
  • Solenix DOCOMO It is shown by the relationship between the current value flowing through the coil 43 and the natural period.
  • the points in the figure are the experimental values obtained by the prototype. As can be seen from Fig. 8A, the calculated values and the experimental values are almost the same.
  • the horizontal sensitive seismometer 10 configured as above operates as follows. That is, when a horizontal vibration is transmitted to the horizontal high-sensitivity seismometer 10 due to an earthquake or the like, a force acts in a direction in which the horizontal pendulum 24 swings in the horizontal direction by the weight 26.
  • the minute displacement of the horizontal pendulum 24 is detected by the capacitance position detector 34.
  • the amount of movement detected by the capacitance position detector 34 corresponds to the deflection angle, and a signal of this deflection angle is input to the control circuit 100 and the amount of current supplied to the solenoid coil 51 Is calculated, and the solenoid coil drive 51 is driven by the feed coil drive unit 104.
  • the movement of the horizontal pendulum 24 is restricted by the circular bar magnet 52.
  • by extracting the output signal of the feedback coil driving unit 104 and the output signal of the capacitance position detector 34 it is possible to obtain a vibration detection output.
  • the horizontal high-sensitivity seismograph 10 according to the embodiment of the present invention, the following effects can be obtained.
  • a servo-type seismometer by supporting a horizontal pendulum using a heavy weight with a weak panel, it is possible to increase the period of the pendulum. it can. For this reason, it is possible to achieve high dynamic range and stability of seismometers.
  • a laser scanhole (maximum relative resolution 35 ⁇ m) may be used instead of the capacitance position detector 34.
  • the laser scale is a method of measuring the movement of a hologram diffraction grating cut in a quartz ruler using a laser interferometer. In this method, is the interference fringe created by the grating fringed and absolutely measured? The phase relationship between the interference waveforms of the two sinuses obtained by the fringe changes and the cosin function is calculated. Or information. Phase measurement has a relative resolution of tens of pm. In this case, a digital feed knock circuit is used as the control circuit.
  • Real-time processing is required because it is necessary to drive the solenoid 51 almost at the same time that displacement information is measured. Therefore, processing must be performed at high speed.
  • digital feedback using a high-speed DSP Digita 1 Signal Processor
  • Digital feedback knocks the feedback circuit and data processing / communication circuit together to reduce the cost. It has the advantage that it can obtain a wide dynamic range by correcting the nonlinear characteristics of the pendulum, and can use adaptive control to correct the change in the characteristics of the detector due to temperature.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Acoustics & Sound (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
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  • Geophysics And Detection Of Objects (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

A horizontal ground motion detector comprises a horizontal pendulum (24) having a forward end where a weight (26) is arranged and a base end, supported by an X-shaped hinge (23), so as to be oscillated in a horizontal plane around the base end, a magnetic levitation mechanism (30) which performs the magnetic levitation of the weight (26) and maintains the oscillating direction of the horizontal pendulum (24) in the horizontal plane, an electrostatic capacity position detector (34) for measuring the swinging angle of the horizontal pendulum (24) in the horizontal direction, a control circuit (100) for calculating the restoration quantity of the horizontal pendulum (24) based on the swinging angle of the horizontal pendulum (24) detected by the electrostatic capacity position detector (34), and a pendulum restoration mechanism (40) for restoring the horizontal pendulum (24) according to the calculation result obtained by the control circuit (100).

Description

明 細 書  Specification
水平地動検出器 Horizontal ground motion detector
技術分野 Technical field
本発明は、 地震計等に用いられる水平地動検出器に関 し、 特に簡単な構成で高精度の測定が行える ものに関する も ので ある。  The present invention relates to a horizontal ground motion detector used for a seismograph or the like, and particularly to a horizontal ground motion detector capable of performing highly accurate measurement with a simple configuration.
背景技術 Background art
S T S (速度計） や C M G (加速度計） 等の広帯域 ' 高感 度地震計や超伝導重力計等の地球観測機器は、 遠地地震の小 さな波形を正確に捕らえる地球の内部 トモグラフ ィ ーを利用 して地球の内部構造を明 らかに した り 、 等の近年の地震研究 に多大な貢献を している。 この よ う な地震研究を発展させる ために、 高感度 ■ 高精度のサーボ型の地震計等が開発されて きた。  Earth observation instruments such as broadband 'high-sensitivity seismometers and superconducting gravimeters, such as STS (speedometer) and CMG (accelerometer), use the internal tomography of the earth to accurately capture the small waveforms of teleseismic earthquakes. It has been used to clarify the internal structure of the earth, and has made a great contribution to recent seismic research. In order to develop such seismic research, high-sensitivity and high-accuracy servo-type seismometers have been developed.
地震計と して、 振り 子を用いて慣性不動点を作り 、 震動す る地面と こ の慣性不動点と の間の変位を測定する こ と で振動 を検出する ものが従来よ り 用い られている。 このよ う な地震 計を高感度 · 広帯域化 し、 特に地震特有の低周波領域の測定 を行 う ためには、 長い自然周期を得る こ と が必要と なる。  Conventionally, seismometers that use a pendulum to create an inertia fixed point and measure the displacement between the vibrating ground and the inertia fixed point to detect vibrations have been used conventionally. I have. In order to increase the sensitivity and bandwidth of such seismographs, and to measure the low-frequency region peculiar to earthquakes, it is necessary to obtain a long natural cycle.
こ こで、 どのよ う に して長い自然周期を得るかが一つの問 題と なる。 長周期を得るために、 例えば、 振り 子の錘を非常 に重いもの とする こ と が考えられる。 し力 しな力 S ら、 このよ う な地震計は大型化する とい う 問題があった。  Here, one problem is how to obtain a long natural cycle. In order to obtain a long period, for example, the weight of the pendulum may be made very heavy. There was a problem that such seismographs would become large in size.
一方、 錘にかかる重力を機械式のパネの復元力で打ち消 し 弱いパネ定数を実現するための倒立振り 子ゃリ一フスプリ ン グタイプの地震計、 さ らにラ コステ重力計で使用 されてレヽる ゼロ長パネが考案されている。 On the other hand, the inverted pendulum is used to cancel the gravity acting on the weight with the restoring force of the mechanical panel to achieve a weak panel constant. A zero-length panel has been devised, which is used in seismometers of the rugged type and in Lacoste gravimeters.
特に最近の水平高感度地震計は、 僅かに倒立させた振 り 子 で重力によ り 板パネの強い復元力を打ち消 し、 その僅かな差 で振り 子の弱いバネを実現し長周期化をはかっている ものが ある。 例えば、 S T S — 1 は、 水平振り 子のヒ ンジに使用 し ている板パネの復元力を打ち消すために、 本体を水平面から 僅かに上に傾け、 その角度調整で振り 子の倒立の具合いを変 えて重力の打ち消 し調整を行っている。  In particular, recent horizontal high-sensitivity seismometers use a slightly inverted pendulum to cancel the strong restoring force of the panel panel due to gravity, and a slight difference realizes a weak pendulum spring and prolongs the period. Some are wearing For example, the STS-1 tilts the main unit slightly upward from the horizontal plane to cancel the restoring force of the panel used for the hinge of the horizontal pendulum, and changes the angle of the pendulum by adjusting its angle. We are making adjustments to cancel gravity.
上述した水平高感度地震計である と次のよ う な問題があつ た。 すなわち、 大き な力同士の打ち消 しで小さなパネ定数を 得る とい う構造であるため、 地面の僅かな傾きや設置誤差、 温度 · 経年変化によ るパネの弾性定数の少 しの変化もその差 を大き く 拡大 · 縮小する。 その差の変化は振り 子全体のパネ 定数の変化にな り 、 自然周期や利得の変動をもた ら し測定値 の ド リ フ ト · ノ イ ズに直結する。 したがって、 その調整や観 測時の設置が難しいとい う 問題があった。  The above-mentioned horizontal high-sensitivity seismometer had the following problems. In other words, since a small panel constant is obtained by canceling out large forces, slight changes in the elastic constant of the panel due to slight inclination of the ground, installation errors, and temperature and aging are also affected. Enlarge and reduce the difference greatly. The change in the difference results in a change in the panel constant of the entire pendulum, which causes a change in the natural period and gain, and is directly linked to the drift noise of the measured value. Therefore, there was a problem that it was difficult to make adjustments and installation during observation.
また設置を容易にするために、 C M Gのよ う に内部に電動 ジンバル機構を持ったものもあるが、 構造が複雑にな り 、 コ ス トが高く なる とい う 問題があった。 さ らに、 パネ機構の設 計と製作は、 非常に特殊な技術を必要とする とい う 問題があ つた。  Some of them, such as CMG, have an electric gimbal mechanism inside for easy installation. However, there was a problem that the structure was complicated and the cost was high. In addition, there was a problem that the design and fabrication of the panel mechanism required very special techniques.
そこで本発明の目的は、 振り 子の長周期化を図る場合であ つても、 弾性部材のパネ定数の変化に伴う ド リ フ ト · ノ イズ の発生を防止 し、 かつ、 調整や観測時の設置を容易にする こ とで、 高ダイナミ ッ ク レンジ化及び安定化が図る こ とができ る水平地動検出器を提供するにある。 Therefore, an object of the present invention is to prevent the generation of drift noise due to a change in the panel constant of the elastic member, and to make adjustments and observations possible even when the period of the pendulum is to be increased. Easy installation Accordingly, it is an object of the present invention to provide a horizontal ground motion detector capable of achieving a high dynamic range and stabilization.
発明の開示 Disclosure of the invention
本発明における水平地動検出器は、 先端側に錘部が設け ら れる と と もに、 基端側が板パネで支持され、 上記基端側を中 心と して水平面内で揺動する水平振り 子と 、 この水平振り 子 の下方に対向配置され上記錘部を磁気浮上させて上記水平振 り 子の揺動方向を水平面内に維持する浮上磁石部と、 前記水 平振り 子の水平方向の振れ角を測定する測定部と、 こ の測定 部による上記水平振り 子の振れ角に基づいて上記水平振り 子 の復元量を算出する演算部と、 こ の演算部によ る算出結果に 基づいて上記水平振り 子を復元する復元部と を備えて構成さ れている。  The horizontal ground motion detector according to the present invention has a weight portion provided on the distal end side, a base end side supported by a panel panel, and a horizontal swing rocking in a horizontal plane with the base end side as a center. A pendulum, a levitation magnet portion disposed opposite to the horizontal pendulum and magnetically levitating the weight to maintain the swinging direction of the horizontal pendulum in a horizontal plane; and a horizontal magnet of the horizontal pendulum. A measuring unit for measuring a swing angle, a calculating unit for calculating a restoration amount of the horizontal pendulum based on a swing angle of the horizontal pendulum by the measuring unit, and a calculation unit based on a calculation result by the calculating unit And a restoring unit for restoring the horizontal pendulum.
図面の簡単な説明 BRIEF DESCRIPTION OF THE FIGURES
図 1 は本発明の一実施の形態に係る水平地動検出器を示す 斜視図である。  FIG. 1 is a perspective view showing a horizontal ground motion detector according to one embodiment of the present invention.
図 2 は同水平地動検出器を示す平面図である。  FIG. 2 is a plan view showing the horizontal ground motion detector.
図 3 は同水平地動検出器を示す側面図である。  Fig. 3 is a side view showing the horizontal ground motion detector.
図 4 は同水平地動検出器を示す背面図である。  Fig. 4 is a rear view showing the horizontal ground motion detector.
図 5 は同水平地動検出器に組み込まれた制御回路を示すブ 口 ッ ク 図である。  Figure 5 is a block diagram showing the control circuit built into the horizontal ground motion detector.
図 6 は磁場強度と浮上力 と磁石面積との関係を示すグラフ である。  Figure 6 is a graph showing the relationship between magnetic field strength, levitation force, and magnet area.
図 7 は錘にかかる力を模式的に示す説明図である。  FIG. 7 is an explanatory diagram schematically showing the force applied to the weight.
図 8 Aはソ レノ ィ ドコイルへの電流と 自然周期と の関係を 示すグラ フである。 Figure 8A shows the relationship between the current to the solenoid coil and the natural period. This is the graph shown.
図 8 B はベース の傾き と 自然周期と の関係を示すグラ フで ある。  Figure 8B is a graph showing the relationship between the inclination of the base and the natural period.
発明を実施するため の最良の形態 BEST MODE FOR CARRYING OUT THE INVENTION
図 1 は本発明の一実施の形態に係る水平高感度地震計 1 0 を示す斜視図、 図 2 は同水平高感度地震計 1 0 を一部切欠 し て示す平面図、 図 3 は同側面図、 図 4 は同水平高感度地震計 1 0 の背面図である。 なお、 これらの図中矢印 X Y Z は互い に直交する三方向を示してお り 、 特に矢印 X Yは水平方向、 矢印 Z は鉛直方向を示 している。  FIG. 1 is a perspective view showing a horizontal high-sensitivity seismometer 10 according to an embodiment of the present invention, FIG. 2 is a plan view showing the horizontal high-sensitivity seismograph 10 partially cut away, and FIG. Figure and Figure 4 are rear views of the horizontal high-sensitivity seismograph 10. In these figures, arrows XYZ indicate three directions orthogonal to each other, and in particular, arrow XY indicates a horizontal direction, and arrow Z indicates a vertical direction.
水平高感度地震計 1 0 は、 いわゆるサーボ型地震計である。 サーボ型地震計は、 錘の位置を検出 しその動き を止める こ と で大きな外力によ る大きな揺れでも振り 子が振り 切れないよ う に したものである。 このこ と で地震計の高ダイナミ ッ ク レ ンジ化及び安定化を図る こ とが可能と なる。 また、 フィ ー ド バッ ク回路から錘に接続されたコ イ ルァク チユエータへの信 号や位置検出回路の出力信号を、 振動検出出力 とする。 さ ら にフィ ー ドバッ クノ、。ラ メ ータによ る補償で、 振り 子の減衰定 数や自然周期等が可変でき る とい う特性を有している。  The horizontal high-sensitivity seismometer 10 is a so-called servo-type seismometer. The servo-type seismometer detects the position of the weight and stops its movement so that the pendulum does not swing even when a large shaking is caused by a large external force. This will enable high dynamic range and stabilization of seismometers. In addition, the signal from the feedback circuit to the coil actuator connected to the weight and the output signal of the position detection circuit are used as the vibration detection output. And feedback. It has the characteristic that the attenuation constant and natural period of the pendulum can be varied by compensation using the parameters.
水平高感度地震計 1 0 は、 測定位置に固定されるベース 1 1 と、 こ のベース 1 1 上に搭載された水平振り 子機構 2 0 、 磁気浮上機構 3 0、 振り 子復元機構 4 0 と、 水平振り 子 2 4 の位置に基づいて振 り 子復元機構 4 0 を制御する制御回路 1 0 0 と を備えている。  The horizontal high-sensitivity seismometer 10 has a base 11 fixed to the measurement position, a horizontal pendulum mechanism 20 mounted on the base 11, a magnetic levitation mechanism 30 and a pendulum restoration mechanism 40. And a control circuit 100 for controlling the pendulum restoring mechanism 40 based on the position of the horizontal pendulum 24.
水平振 り 子機構 2 0 は、 X Y Zテーブル 2 1 と、 この X Y Zテーブル 2 1 に支持された振り 子支持部 2 2 と、 こ の振り 子支持部 2 2 に X型ヒ ンジ 2 3 を介 して取付け られた水平振 り 子 2 4 と、 こ の水平振り 子 2 4 の先端側下部に取付け られ た板状のブラケッ ト 2 5 と、 こ のブラケッ ト 2 5 の下面に取 付け られた錘 2 6 と、 この錘 2 6 を挟んで配置された一対の 上側磁石部 2 7， 2 8 と を備えている。 The horizontal pendulum mechanism 20 is composed of the XYZ table 21 and the XY The pendulum support 22 supported on the Z table 21, the horizontal pendulum 24 attached to the pendulum support 22 via the X-shaped hinge 23, and the horizontal pendulum A plate-like bracket 25 attached to the lower part of the tip side of the child 24, a weight 26 attached to the lower surface of the bracket 25, and a pair of Upper magnet parts 27 and 28 are provided.
X Y Zテープノレ 2 1 は、 3 つの調節ネジ 2 1 a〜 2 1 c に よ り X Y Z方向について移動可能に構成されてお り 、 例えば 錘 2 6 の質量を変えた場合に、 磁石浮上機構 3 0 によ る磁気 浮上が適正に行われる よ う に調節する こ と が可能である。  The XYZ taper 21 is configured to be movable in the XYZ direction by three adjusting screws 21a to 21c.For example, when the mass of the weight 26 is changed, the It can be adjusted so that the magnetic levitation is performed properly.
X型ヒ ンジ 2 3 は、 恒弾性合金 （ハイテ リ ンバー） の板バ ネによ り 形成されてお り 、 振り 子支持部 2 2及び水平振り 子 2 4 にネジ止め されている。 こ の X型ヒ ンジ 2 3 によ り 水平 振り 子 2 4 は振り 子支持部 2. 2 に対し、 その中心軸 2 3 a を 摇動軸と して揺動可能に支持されている。 なお、 中心軸 2 3 a は鉛直方向である こ とから、 水平振り 子 2 4 の揺動範囲は 水平面内 と なる。  The X-shaped hinge 23 is formed of a plate spring made of a constant elastic alloy (high terember), and is screwed to the pendulum support 22 and the horizontal pendulum 24. The horizontal pendulum 24 is swingably supported by the X-shaped hinge 23 on the pendulum support part 2.2 with its central axis 23a as a pivot axis. Since the center axis 23a is in the vertical direction, the swing range of the horizontal pendulum 24 is in the horizontal plane.
上側磁石部 2 7 , 2 8 は、 X型ヒ ンジ 2 3 の中央軸 2 3 a を中心 と した 円弧状に N極と S 極の細い帯状磁石 （数 m m 幅） が交互に配置されたものから構成されている。 なお、 帯 状磁石の代わ り に N極 · S極を交互に着磁した磁石を用いて も よい。  The upper magnets 27 and 28 are formed by alternately arranging narrow N-pole and S-pole magnets (a few mm wide) in an arc centered on the central axis 23a of the X-shaped hinge 23. It is composed of It should be noted that a magnet in which N and S poles are alternately magnetized may be used instead of the band magnet.
磁気浮上機構 3 0 は、 架台 3 1 と、 この架台 3 1 上に設け られ、 上述 した上側磁石部 2 7， 2 8 に対向配置された下側 磁石部 3 2， 3 3 と、 非接触で水平振り 子 2 4 の振れ角を検 出する静電容量位置検出器 3 4 と を備えている。 The magnetic levitation mechanism 30 is provided in a non-contact manner with the frame 31 and the lower magnet portions 32, 33 provided on the frame 31 and opposed to the upper magnet portions 27, 28 described above. Check the swing angle of the horizontal pendulum 24. And a capacitance position detector 34 which emits the capacitance.
下側磁石部 3 2 ， 3 3 は、 X型ヒ ンジ 2 3 の中央軸 2 3 a を中心 と した 円弧状に N極と S極の細い帯状磁石 （数 m m 幅） が交互に配置されたものから構成されている。 なお、 帯 状磁石の代わ り に N極 · S極を交互に着磁した磁石を用いて ち ょい。  In the lower magnet sections 32 and 33, strip-shaped magnets (several mm width) with N poles and S poles are arranged alternately in an arc centered on the central axis 23a of the X-shaped hinge 23. It is composed of things. It should be noted that instead of the band magnet, a magnet in which N and S poles are alternately magnetized is used.
このと き、 上述した上側磁石部 2 7 ， 2 8 における N極と 下側磁石部 3 2 ， 3 3 の N極と が対向する よ う に、 上側磁石 部 2 7 ， 2 8 における S極と下側磁石部 3 2 , 3 3 の S極と 対応する よ う に配置されている。 このこ と で永久磁石の直上 平面では磁場の位置エネルギーを均一にでき、 錘 2 6 の安定 浮上が実現でき る。  At this time, the S poles of the upper magnet sections 27 and 28 are arranged such that the N poles of the upper magnet sections 27 and 28 and the N poles of the lower magnet sections 32 and 33 face each other. It is arranged so as to correspond to the S pole of the lower magnet sections 32 and 33. As a result, the potential energy of the magnetic field can be made uniform on the plane directly above the permanent magnet, and the weight 26 can be stably levitated.
静電容量位置検出器 3 4 は、 ターゲッ トである参照質量と 検出器にある電極と の間の変位に比例 した静電容量を測定す る も のであ り 、 アナロ グ値と して出力される。 静電容量位置 検出器 3 4 の最大分解能は例えば 0 . 5 n mである。  The capacitance position detector 34 measures the capacitance proportional to the displacement between the target reference mass and the electrode on the detector, and is output as an analog value. You. The maximum resolution of the capacitance position detector 34 is, for example, 0.5 nm.
なお、 上述 した上側磁石部 2 7 ， 2 8及び下側磁石部 3 2 ， 3 3 で用いる永久磁石は、 例えば、 希土類であるネオジゥム コノ ル トゃフェライ トシー トであって 0 . 2 T以上の磁場を 発生する ものを用いる。 希土類の永久磁石の磁場強度は、 磁 場の転移点であるキューリ 一温度に達するまでは大き な温度 依存性が無く 、 また僅かな強度の温度依存性があっても浮上 は鉛直方向なので、 水平振 り 子にはほとんど影響 しない。 希 土類の永久磁石を用いた場合、 1 0 k g の錘を 3 次元空間内 の 1 軸を板パネ等で拘束する こ と で安定に浮上でき る こ とが 明 らかになつている。 The permanent magnets used in the upper magnet portions 27 and 28 and the lower magnet portions 32 and 33 described above are, for example, rare earth neodymium conoferrite sheets having 0.2 T or more. Use a device that generates a magnetic field. The magnetic field strength of a rare earth permanent magnet does not have a large temperature dependence until it reaches the Curie temperature, which is the transition point of the magnetic field, and even if there is a slight temperature dependence, the levitation is in the vertical direction. Has little effect on pendulum. When a rare-earth permanent magnet is used, a 10 kg weight can be stably levitated by constraining one axis in a three-dimensional space with a panel, etc. It is clear.
振 り 子復元機構 4 0 は、 架台 4 1 と、 こ の架台 4 1 に支持 された磁気パネ機構 4 2 と 、 フ ィ ー ドバッ ク機構 5 0 と を備 えている。 磁気パネ機構 4 2 は、 矢印 Y方向に沿つた磁場軸 を形成する ソ レ ノ ィ ドコィノレ 4 3 と、 軸方向を矢印 Y方向 と しその先端が水平振り 子 2 4 に当接して配置された円形棒磁 石 4 4 と を備えている。 ソ レノ ィ ドコイル 4 3 には制御回路 1 0 0 によ り 通電される こ とで、 円形棒磁石 4 4 に駆動力を 与えて、 水平振り 子 2 4 の 自然周期を変える こ と が可能であ る。 こ こ で、 磁気パネ機構 4 2 に よ る駆動力を f m ag とす る。  The pendulum restoring mechanism 40 includes a gantry 41, a magnetic panel mechanism 42 supported by the gantry 41, and a feedback mechanism 50. The magnetic panel mechanism 42 has a solenoid docoinole 43 that forms a magnetic field axis along the direction of the arrow Y, and an axial direction that is in the direction of the arrow Y, and the tip of which is in contact with the horizontal pendulum 24. It has a circular bar magnet 4 and 4. When the solenoid coil 43 is energized by the control circuit 100, it can apply a driving force to the circular bar magnet 44 to change the natural cycle of the horizontal pendulum 24. is there. Here, the driving force of the magnetic panel mechanism 42 is defined as f m ag.
フ ィ ー ドバック機構 5 0 は、 矢印 Y方向に沿った磁場軸を 形成する ソ レ ノ ィ ドコ イ ル 5 1 と 、 軸方向を矢印 Y方向 と し その先端が水平振り 子 2 4 に当接 して配置された円形棒磁石 5 2 と を備えている。 ソ レノィ ドコィノレ 5 1 は後述するフィ 一ド ノ ッ ク コイル駆動部 1 0 4 によ り 通電 · 駆動される こ と で、 円形棒磁石 4 4 に駆動力を与えて、 水平振り 子 2 4 の動 き を規制する ものである。  The feedback mechanism 50 has a solenoid coil 51 that forms a magnetic field axis along the arrow Y direction, and a tip that contacts the horizontal pendulum 24 with the axial direction as the arrow Y direction. And a circular bar magnet 52 arranged in a row. The solenoid 51 is energized and driven by a feed knock coil drive unit 104, which will be described later, applies a driving force to the circular bar magnet 44 and applies a driving force to the horizontal pendulum 24. It regulates movement.
制御回路 1 0 0 は、 アナロ グフィ ー ドバッ ク回路であって、 図 5 に示すよ う に、 静電容量位置検出器 3 4 からの出力を増 幅するプリ アンプ 1 0 1 と 、 位相補償器 1 0 2 と、 フィ ー ド ノ ッグフイ ノレタ 1 0 3 と、 ソ レ ノ ィ ドコィノレ 4 3 を駆動する フィ ー ドノ ック コ イ ル駆動部 1 ◦ 4 と を備えている。  The control circuit 100 is an analog feedback circuit, and as shown in FIG. 5, a preamplifier 101 for amplifying the output from the capacitance position detector 34, and a phase compensator. And a feed knock coil drive section 1 4 4 for driving a feed knock coil 43, and a feed knock coil drive section 1 4 4 for driving the solenoid coil 43.
次に、 磁気浮上機構 3 0 及び X型ヒ ンジ 2 3 を用いて長周 期の振り 子を実現している点について詳述する。 すなわち、 振 り 子を支持するために用い られる弾性部材のパネ定数の変 動はバネの弾性定数に対する比率で決ま る こ と か ら、 バネ定 数の変動の絶対値を小さ く する には弱い （柔 らかい） 金属バ ネを用いる こ と が好ま しい。 しか し弱い金属パネで支え られ る錘は軽いものに限 られる。 そ こで、 パネ系 と は独立に錘を 支え、 無定位な状態を作る と と も に、 錘に金属または別の方 法で弱いパネ機構を付加 して、 長周期振 り 子を作る'こ と が求 め られる。 Next, the fact that a long-period pendulum is realized using the magnetic levitation mechanism 30 and the X-shaped hinge 23 will be described in detail. That is, Since the fluctuation of the panel constant of the elastic member used to support the vibrator is determined by the ratio to the elastic constant of the spring, it is weak to reduce the absolute value of the fluctuation of the spring constant. It is preferable to use metal springs. However, the weight supported by the weak metal panel is limited to light ones. Therefore, the weight is supported independently of the panel system to create an asymmetric state, and a weak panel mechanism is added to the weight using metal or another method to create a long-period oscillator. This is required.
したがって、 水平振 り 子 2 4 を磁気浮上機構 3 0 で支持す る と と も に、 弱いバネ機構 と して X型ヒ ンジ 2 3 を用いた。 この よ う に、 X型ヒ ンジ 2 3 に対する錘 2 6 の負荷を ごく 僅 かとする こ と ができ る こ と 力 ら、 X型ヒ ンジ 2 3 を弱い板バ ネで構成でき長周期化が可能と なる。 さ ら に、 振 り 子の 自然 周期を固定 して考えた と き には、 軽い鲤の使用で地震計の軽 量化も期待でき る。  Therefore, the horizontal pendulum 24 was supported by the magnetic levitation mechanism 30 and the X-shaped hinge 23 was used as a weak spring mechanism. As described above, since the load of the weight 26 on the X-shaped hinge 23 can be reduced to a very small value, the X-shaped hinge 23 can be constituted by a weak plate spring, and the period can be increased. It will be possible. Furthermore, when the natural period of the pendulum is fixed, it is expected that the use of a light 鲤 will make the seismograph lighter.
なお、 重力に対する錘の支持と振り 子の機能を分離 して構 造を単純にする こ と で、 設置誤差等で生 じる傾き に起因 した 相互干渉に よ る悪影響も除 く こ と が可能と な る。  By separating the function of the weight from gravity and the function of the pendulum to simplify the structure, it is also possible to eliminate the adverse effects due to mutual interference caused by tilt caused by installation errors, etc. It becomes.
永久磁石で浮上でき る錘 2 6 の重量は、 水平振 り 子 2 4 の 自 然周期を決めるパラ メ ータ である。 こ こ では、 簡略化 した 例 と して対向する永久磁石によ る浮上重量の計算結果を述べ る。 伹 し、 N S 交互着磁の浮上用磁石でも ほぼ同 じ結果が得 られる。 対向する磁石の吸引力 F は、  The weight of the weight 26 that can be levitated by the permanent magnet is a parameter that determines the natural period of the horizontal pendulum 24. Here, as a simplified example, the calculation results of the flying weight by the opposing permanent magnets are described. However, almost the same results can be obtained with the levitation magnets of Ns alternately magnetized. The attractive force F of the opposing magnet is
, B2 S , B 2 S
F 丄 …(つ  F…… (T
2 μ で表 される。 こ こ で B g は対向する磁極問の磁束密度、 μ は透磁率、 S は磁極間の対向面積である。 反発力も同様に成 り 立つ。 この式 （ 1 ) を使って磁力を変えた と き の水平振り 子 2 4 に使 う錘 2 6 の浮上力を計算 した結果を図 6 中実線に 示す。 また、 図 6 中のポイ ン ト Ρ は実験値を示す。 N S交互 着磁の浮上用磁石は磁力線が帯と帯の間に閉 じるので、 強い 磁場の範囲は近傍のみである。 その範囲は大き く 見ても表面 から数 + m mの程度である。 そのために浮上用磁場の漏れに よる X型ヒ ンジ 2 3 等に対する影響も少な く でき る。 2 μ It is represented by Here, B g is the magnetic flux density between the facing magnetic poles, μ is the magnetic permeability, and S is the facing area between the magnetic poles. The resilience also holds. The results of calculating the levitation force of the weight 26 used for the horizontal pendulum 24 when the magnetic force is changed using this equation (1) are shown in the solid line in FIG. Point 中 in Fig. 6 indicates the experimental value. NS Alternating magnetized levitation magnets have a strong magnetic field only in the vicinity because the magnetic field lines are closed between the bands. The range is about several mm from the surface at a glance. Therefore, the influence on the X-shaped hinge 23 and the like due to the leakage of the magnetic field for levitation can be reduced.
しかし範囲が狭く ても、 上側磁石部 2 7 , 2 8 を下側磁石 部 3 2 , 3 3 に対向 して近づければ、 磁石近傍では 0 . 5 T 程度の磁場強度が期待でき る。 図 6 のグラ フから磁石の面積 S にも よ るが、 1 0 0 0 m m 2 程度の面積で 2 k g 程度の 重量の錘 2 6 を浮上させる こ と ができ、 実験値は計算値に合 致している。 However, even if the range is narrow, a magnetic field strength of about 0.5 T can be expected in the vicinity of the magnet if the upper magnets 27 and 28 are brought close to and opposed to the lower magnets 32 and 33. Although Ru good in the area S from the graph of the magnet of FIG. 6, 1 0 0 0 mm 2 about an area to weight 2 6 weight about 2 kg can trigger levitated, the experimental value if the calculated value I do.
次に、 水平振り 子 2 4 の動作特性について説明する。 水平 振り 子 2 4 の動作特性は、 主に X型ヒ ンジ 2 3 の板パネの復 元力 f re s で決ま る。 こ こ で、 磁気パネ機構 4 2 の力 を f m ag とする。 また本体が傾斜する こ と に よ り 、 重力 f g に よ る X型ヒ ンジ 2 3 の復元力を打ち消すよ う な負の力 f g s in が錘 2 6 に対して働く 。 こ の錘 2 6 に働く 力の関係を模式的 に示 したのが図 7である。  Next, the operating characteristics of the horizontal pendulum 24 will be described. The operating characteristics of the horizontal pendulum 24 are mainly determined by the restoring force fres of the panel of the X-shaped hinge 23. Here, the force of the magnetic panel mechanism 42 is defined as f m ag. In addition, since the main body is tilted, a negative force f g s in acting on the weight 26 to cancel the restoring force of the X-shaped hinge 23 due to the gravity f g acts on the weight 26. Fig. 7 schematically shows the relationship between the forces acting on the weight 26.
図 7 中の力で Y— Z平面 （ Y軸の傾き） に沿った本体の傾 き （回転成分） は、 水平振り 子 2 4 の平衡点のシフ ト につな が り 、 こ の検出器は原理的に水平動の外力 と こ の成分を区別 でき ない。 X _ Z 平面 （ X軸の傾き） に沿っ た本体の傾き (回転成分） はパネ定数の変化につながる。 水平振り 子 2 4 に働く 外力 とそれぞれの力の関係は、 d2xd dxH , n Mgspnl fext = m ~~ -^- + ε ~ 一 Xd (k— mgSin ^ Sin 土 ¾ μ ) The tilt (rotation component) of the main unit along the Y-Z plane (tilt of the Y axis) with the force in Fig. 7 leads to the shift of the equilibrium point of the horizontal pendulum 24, and this detector In principle distinguishes this component from the external force of horizontal motion Can not. The tilt (rotation component) of the body along the X_Z plane (X-axis tilt) leads to a change in the panel constant. The relation between the external force acting on the horizontal pendulum 24 and each force is d 2 x d dx H , n M gsp nl f ext = m ~~-^-+ ε ~ one Xd (k— mgSin ^ Sin soil μ )
dt2 dt 2な dt 2 dt 2
… (2) で表され、 この式 （ 2 ) では Y— Z平面に沿った傾き は無い も の とする。 錘 2 6 に働 く 重力 f g は、 磁気浮上力 f l eve l で打ち消され式 （ 2 ) に表れない。 こ こで f ext は外力、 m は参照質量、 ε は減衰係数、 k は X型ヒ ンジ 2 3 のパネ定数、 g は重力加速度、 φ は水平振り 子 2 4 の倒立の具合を決める 角度、 0 は水平振り 子 2 4 の振れ角、 M g sp は磁気パネ機構 4 2 の内部棒磁石の磁荷、 11 は磁気パネ機構 4 2 の ソ レノ ィ ドコイル 4 3 の卷き数、 I はソ レノ ィ ドコィノレ 4 3 の電流、 α はソ レ ノ イ ドコ イ ル 4 3 の半径、 x d は水平振 り 子 2 4 の変位である。 また右辺の括弧内の第 1 項は X型ヒ ンジ 2 3 の復元力 ί res で、 第 2項は水平振り 子 2 4 の錘 2 6 に働く 重力によ る倒立力 f gs in、 第 3 項は磁気パネ機構 4 2 によ る 力 f mag である。  (2), and in this equation (2), it is assumed that there is no inclination along the Y-Z plane. The gravity f g acting on the weight 26 is canceled by the magnetic levitation force f l eve l and does not appear in equation (2). Where f ext is the external force, m is the reference mass, ε is the damping coefficient, k is the panel constant of the X-shaped hinge 23, g is the gravitational acceleration, φ is the angle that determines the degree of inversion of the horizontal pendulum 24, 0 is the deflection angle of the horizontal pendulum 24, M gsp is the magnetic charge of the internal rod magnet of the magnetic panel mechanism 42, 11 is the number of turns of the solenoid coil 43 of the magnetic panel mechanism 42, and I is the number of turns. The current of the laser coil 43, α is the radius of the solenoid coil 43, and xd is the displacement of the horizontal oscillator 24. The first term in the parentheses on the right side is the restoring force ί res of the X-shaped hinge 23, and the second term is the inverting force f gs in due to gravity acting on the weight 26 of the horizontal pendulum 24. The term is the force f mag by the magnetic panel mechanism 42.
地震計のノ イ ズにつながる外力は、 上記の傾斜成分のほか に音や気圧変化等多様なも のがある。 この式 （ 2 ) を使って 磁気バネ機構 4 2 で X型ヒ ンジ 2 3 と逆方向の負の復元力を 加え、 水平振り 子 2 4 の自然周期が長く なる方向に変化させ た と きの計算値を図 8 A中実線で示す。 なお、 ソ レノ ィ ドコ ィル 4 3 に流す電流値と 自然周期 と の関係で示されている。 また、 図中のポイ ン トは、 試作機によ って得られた実験値で ある。 図 8 Aからわかる よ う に、 計算値と実験値はほぼ一致 している。 The external force that leads to the noise of the seismometer has a variety of things such as sound and pressure change in addition to the above-mentioned tilt component. Using this equation (2), the magnetic spring mechanism 42 applies a negative restoring force in the direction opposite to that of the X-shaped hinge 23, and changes the natural period of the horizontal pendulum 24 in the direction to increase. The calculated value is shown by the solid line in Fig. 8A. In addition, Solenix DOCOMO It is shown by the relationship between the current value flowing through the coil 43 and the natural period. The points in the figure are the experimental values obtained by the prototype. As can be seen from Fig. 8A, the calculated values and the experimental values are almost the same.
一方、 X— Z平面 （ X軸の傾き） でベー ス 1 1 を傾け、 水 平振り 子 2 4 の復元力を変化させたと きの傾き角に依存した 自然周期の変化の計算値を図 8 B に示す。 なお、 試作機の参 照質量は 2 kg程度である。  On the other hand, when the base 11 is tilted on the X—Z plane (tilt of the X axis) and the restoring force of the horizontal pendulum 24 is changed, the calculated value of the change in natural period depending on the tilt angle is shown in Fig. 8. See B. The reference mass of the prototype is about 2 kg.
こ の よ う に構成された水平高感度地震計 1 0 は、 次のよ う に動作する。 すなわち、 地震等によ り 水平高感度地震計 1 0 に水平方向の振動が伝わる と、 錘 2 6 によって水平振り 子 2 4 が水平方向に振れる方向に力が働く 。 こ の水平振り 子 2 4 の微小な移動量を静電容量位置検出器 3 4 が検出する。 静電 容量位置検出器 3 4 で検出された移動量は振れ角に対応 し、 この振れ角 の信号は、 制御回路 1 0 0 に入力され、 ソ レノ ィ ド コ ィ ノレ 5 1 への通電量が算出され、 フ ィ ー ドノく ック コィノレ 駆動部 1 0 4 に よ り ソ レノ ィ ドコ ィノレ 5 1 が駆動される。 そ して、 円形棒磁石 5 2 によ り水平振り 子 2 4 の動きが規制さ れる。 同時に、 フィ ー ドバック コ イル駆動部 1 0 4 の出力信 号や静電容量位置検出器 3 4 の出力信号を取り 出すこ と によ り 、 振動検出出力とする こ とができ る。  The horizontal sensitive seismometer 10 configured as above operates as follows. That is, when a horizontal vibration is transmitted to the horizontal high-sensitivity seismometer 10 due to an earthquake or the like, a force acts in a direction in which the horizontal pendulum 24 swings in the horizontal direction by the weight 26. The minute displacement of the horizontal pendulum 24 is detected by the capacitance position detector 34. The amount of movement detected by the capacitance position detector 34 corresponds to the deflection angle, and a signal of this deflection angle is input to the control circuit 100 and the amount of current supplied to the solenoid coil 51 Is calculated, and the solenoid coil drive 51 is driven by the feed coil drive unit 104. The movement of the horizontal pendulum 24 is restricted by the circular bar magnet 52. At the same time, by extracting the output signal of the feedback coil driving unit 104 and the output signal of the capacitance position detector 34, it is possible to obtain a vibration detection output.
上述したよ う に本発明の一実施の形態に係る水平高感度地 震計 1 0 によれば、 次のよ う な効果が得られる。 すなわち、 サーボ型地震計において、 重い錘を用いた水平振り 子を弱い パネで支持する こ と によ り 、 振り 子の長周期化を図る こ とが でき る。 こ のた め、 地震計の高ダイナミ ック レ ンジ化及ぴ安 定化が図る こ と が可能と なる。 また、 強い板パネを用いた場 合の温度変化に依存した ドリ フ トゃ複雑なパネ による重力の 打ち消 し機構に起因する設置の困難性を排除する こ と が可能 である。 As described above, according to the horizontal high-sensitivity seismograph 10 according to the embodiment of the present invention, the following effects can be obtained. In other words, in a servo-type seismometer, by supporting a horizontal pendulum using a heavy weight with a weak panel, it is possible to increase the period of the pendulum. it can. For this reason, it is possible to achieve high dynamic range and stability of seismometers. In addition, it is possible to eliminate the difficulty of installation due to the drift that depends on the temperature change when a strong panel is used and the mechanism for canceling gravity due to the complicated panel.
また、 水平高感度地震計 1 0 では、 錘 2 6 の浮上を永久磁 石を用いた磁気浮上によって実現してい る ので、 電力消費を 小さ く でき、 地震計のよ う に野外で設置する機器に適 してい る。  In the horizontal high-sensitivity seismometer 10, the levitation of the weight 26 is realized by magnetic levitation using permanent magnets, so power consumption can be reduced, and equipment installed outdoors like a seismometer Suitable for
なお、 静電容量位置検出器 3 4 の代わ り に レーザス ケーノレ (最大相対分解能 3 5 p m ) を用いても良い。 レーザス ケー ルでは、 石英の物差しに刻んであるホロ グラム回折格子の動 き を レーザ干渉計によ り 測定する方法である。 こ の方法では. 格子で作られる干渉縞をフ リ ンジカ ゥ ン ト し絶対測定するか. 縞の変化によ り 得られる 2 つのサイ ンと コサイ ン関数の干渉 波形の位相関係を求めて変位情報とするかである。 位相測定 は数十 p mの相対分解能がある。 なお、 この場合、 制御回路 と してはデジタルフィ ー ドノ ッ ク 回路を用いる。  It should be noted that a laser scanhole (maximum relative resolution 35 μm) may be used instead of the capacitance position detector 34. The laser scale is a method of measuring the movement of a hologram diffraction grating cut in a quartz ruler using a laser interferometer. In this method, is the interference fringe created by the grating fringed and absolutely measured? The phase relationship between the interference waveforms of the two sinuses obtained by the fringe changes and the cosin function is calculated. Or information. Phase measurement has a relative resolution of tens of pm. In this case, a digital feed knock circuit is used as the control circuit.
変位情報を計測する と ほぼ同時にソ レ ノ ィ ドコィノレ 5 1 を 駆動する必要がある こ とから、 リ アルタイ ム処理が必要であ る。 したがって、 処理は高速に行 う必要がある。 このよ う な 高速の非線形データ処理には高速の D S P ( D i g i t a 1 S i g n a l P r o c e s s o r ) を使ったデジタ ノレフィ ー ドバック が最適である。 デジタ ノレフ イ ー ドノ ッ ク では、 フ ィ ー ドバッ ク回路とデータ処理 · 通信回路を一体化 して低価 格に した り 、 振り 子の非線形特性を補正し広いダイナミ ック レ ンジを得た り 、 温度によ る検出器の特性変化を補正するァ ダプティ ブ制御が使用でき る等の利点がある。 Real-time processing is required because it is necessary to drive the solenoid 51 almost at the same time that displacement information is measured. Therefore, processing must be performed at high speed. For such high-speed nonlinear data processing, digital feedback using a high-speed DSP (Digita 1 Signal Processor) is optimal. Digital feedback knocks the feedback circuit and data processing / communication circuit together to reduce the cost. It has the advantage that it can obtain a wide dynamic range by correcting the nonlinear characteristics of the pendulum, and can use adaptive control to correct the change in the characteristics of the detector due to temperature.
なお、 地震計にデジタルフィ ー ドバック を採用する場合に 問題であった信号入力 · 出力のための A D C · D A Cのダイ ナミ ック レ ンジの不足は、 必要な範囲をカバーする ビッ ト幅 を上位と下位ビ ッ ト群に分け、 それぞれに対応する各 2 つの A D Cや D A Cで高ビッ ト化して対応するか、 デルタ ■ シグ マ方式の 2 4 ビッ ト D A C を使用する こ と も可能である。  In addition, the lack of dynamic range of ADCs and DACs for signal input and output, which was a problem when digital feedback was adopted for seismometers, resulted in a higher bit width covering the required range. It is also possible to use two ADCs or DACs corresponding to each of them to increase the number of bits, or to use a delta-sigma 24-bit DAC.
なお、 本発明は前記実施の形態に限定される ものではな く 、 本発明の要旨を逸脱しない範囲で種々変形実施可能であるの は勿論である。  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.
産業上の利用可能性 Industrial applicability
本発明によれば、 振り 子の長周期化を図る場合であっても、 弾性部材のパネ定数の変化に伴 う ドリ フ ト ■ ノ イ ズの発生を 防止 し、 かつ、 調整や観測時の設置を容易にする こ と で、 高 ダイナミ ッ ク レ ンジ化及び安定化が図る こ と が可能な水平地 動検出器が得られる。  ADVANTAGE OF THE INVENTION According to this invention, even if it aims at making the period of a pendulum longer, the generation of the drift noise due to the change of the panel constant of the elastic member can be prevented, and at the time of adjustment and observation. By facilitating the installation, a horizontal ground motion detector capable of achieving high dynamic range and stabilization can be obtained.

Claims

4 求 の 4 requests
1 . 先端側に錘部が設け られる と と もに、 基端側が板バ ネで支持され、 上記基端側を中心と して水平面内で揺動する 水平振り 子と、  1. A horizontal pendulum having a weight portion on the distal end side, a base end side supported by a plate spring, and swinging in a horizontal plane about the base end side;
ロ  B
こ の水平振り 子の下冑方に対向配置され上記錘部を磁気浮上 させて上記水平振り 子の揺動方向を水平面内に維持する浮上 磁石部と、  A levitation magnet section disposed opposite to the lower arm of the horizontal pendulum to magnetically levitate the weight and maintain the swinging direction of the horizontal pendulum in a horizontal plane;
前記水平振り 子の水平方向の振れ角を測定する測定部と、 こ の測定部による上記水平振り 子の振れ角に基づいて上記 水平振り 子の復元量を算出する演算部と、  A measuring unit for measuring a horizontal swing angle of the horizontal pendulum; and a calculating unit for calculating a restoration amount of the horizontal pendulum based on the swing angle of the horizontal pendulum by the measuring unit.
こ の演算部による算出結果に基づいて上記水平振り 子を復 元する復元部と を備えている こ と を特徴とする水平地動検出 And a restoring unit for restoring the horizontal pendulum based on the calculation result by the calculating unit.
^ o ^ o
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JPS477022Y1 (en) * 1969-04-02 1972-03-13

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