Servo type vibration detector

Abstract

A servo-type vibration detector and a vibration control device are provided. A movable member coupled to a displacement detector is disposed with a gap relative to a fixed member having a coil fixed thereto. By disposing the coil in a closed magnetic circuit formed by a permanent magnet, the movable member, and the fixed member, a Lorentz force is generated that moves the movable member in an axial direction.

Description

Technical Field

[0001] This invention relates to a vibration sensor or vibration damping control device that detects the acceleration of a controlled object that is supported on a foundation and vibrates under disturbance over a wide frequency band, or its absolute velocity or absolute displacement relative to inertial space. Background Technology

[0002] 1. Trends of the Times

[0003] Vibration control is widely used in various fields such as semiconductor manufacturing, LCD manufacturing, and precision machining to block / suppress minute vibrations. Microfabrication / inspection equipment used in these processes, such as scanning electron microscopes and semiconductor steppers, requires stringent vibration tolerance conditions to ensure equipment performance. Going forward, with the increasing integration and miniaturization of products, the increasing speed of processing, and the growing size of equipment, vibration tolerance conditions are becoming increasingly stringent.

[0004] 2. Interference that the vibration damping device should remove.

[0005] In recent years, active vibration control technology, which generates control signals and controls control devices based on displacement, velocity, and acceleration information from vibration sensors located at multiple locations on the structure (such as a precision vibration damping table) of the vibration control object, is becoming increasingly popular.

[0006] Figure 52 This diagram shows a model of an existing active vibration damping table. Such an active vibration damping table is known as described in Patent Document 3. Multiple sets of air pressure actuators (502a, 502b) are arranged on the ground 500 to support the platform 501. Precision devices (not shown) are mounted on the platform 501. 503 is an accelerometer for detecting the vertical / horizontal acceleration of the platform 501, and 504 is an accelerometer for detecting the acceleration of the ground 500 (the vibration state of the foundation). 505a and 505b are displacement sensors for detecting the vertical / horizontal relative displacement of the platform 501 relative to the ground 500, respectively. The output signals from these sensors are input to a controller 506. A servo valve 508 controlled by the controller 506 is connected to the air pressure actuator 502a via piping 507. The flow rate of compressed air supplied to / discharged from the air pressure actuator 502a is adjusted by the servo valve 508, thereby controlling the internal pressure of the actuator 502a to drive the air pressure actuator.

[0007] The interferences that should be removed in vibration damping devices can be broadly categorized into ground vibration interference caused by the vibration of the floor and linear motion interference input from the vibration damping platform.

[0008] As sources of vibration that cause ground vibration interference, vibrations caused by human movement (known as walking vibration) occur at frequencies of 1–3 Hz, those caused by motors such as air conditioners at frequencies of 6–35 Hz, and the resonant points of floors or walls at approximately 10–100 Hz. High-rise / vibration-free buildings have a natural vibration frequency around 0.2–0.3 Hz. Furthermore, buildings generate micro-vibrations of 0.1–1.0 Hz due to wind swaying. Therefore, vibration damping tables need to suppress not only high-frequency vibrations but also eliminate low-frequency vibrations.

[0009] As a source of high-frequency vibrations caused by linear motion interference, when a vibration damping platform, for example, is equipped with a positioning platform 509, the structure, including the vibration damping platform, is impacted by the acceleration and deceleration of the platform, and sways due to the driving reaction force. If the vibrations caused by this impact and the swaying caused by the driving reaction force are not suppressed, the performance of the platform cannot be maintained. In short, the vibration damping device must possess both the functions of "vibration damping" against ground vibration interference and "vibration prevention" against linear motion interference.

[0010] 3. The role of vibration sensors in active vibration damping devices

[0011] In active vibration control, a state feedback-based control method is employed. This method controls the control device based on acceleration / velocity / displacement information from vibration sensors located at multiple locations on the structure being controlled. To achieve vibration damping performance over a wide frequency range, for example, acceleration signals are primarily used to control state variables above 10Hz, velocity signals are used to control state variables from 1 to 10Hz, and displacement signals are used to control state variables below 1Hz. For example:

[0012] (i) If using an acceleration sensor configured on platform 501 (using...) Figure 52 Using the signal from the accelerometer 503 to implement acceleration feedback is equivalent to increasing the mass M, which can achieve effects such as reducing the natural vibration frequency and reducing the resonance peak.

[0013] (ii) If the acceleration sensor mentioned above ( Figure 52 If the signal of 503 is converted into an absolute velocity or absolute displacement signal and feedback or feedforward is implemented, the vibration damping performance can be greatly improved over a wide frequency range.

[0014] (iii) If using an accelerometer located directly below platform 501 ( Figure 52 The signal of 504) is converted into an absolute velocity or absolute displacement signal, and feedforward is applied in the same way, which can improve the vibration damping performance over a wide frequency range.

[0015] To perform the control described in (ii) and (iii) above, velocity and position information relative to inertial space are required. An accelerometer can measure acceleration relative to inertial space; therefore, by mounting the accelerometer on the controlled object, the acceleration applied to the controlled object can be detected. Thus, in existing active vibration damping devices, the following method is used: the velocity signal is obtained by integrating the output of the accelerometer once, and the displacement signal is obtained by integrating it twice.

[0016] 4. Basic structure and detection principle of accelerometer

[0017] Figure 53 This is a model diagram illustrating the basic structure and detection principle of an electrostatic capacitive accelerometer. 301 is the main body housing the sensor's components; 302 is the mass; 303 is a spring mechanically supporting the mass 302 relative to the vibration measurement surface A; and 304 is an attenuator. The mass 302 also serves as the movable side electrode of the electrostatic capacitive sensor. 305 is the fixed side electrode positioned on the opposite side of the movable side electrode (mass 302), and 306 is the gap between the two electrodes.

[0018] 307 is an electromagnetic actuator that drives the mass 302 in the vertical direction relative to the vibration measurement surface A. Since the electrostatic capacitance C is determined by the size of the gap in the void 306, the relative displacement UX, which is the difference between the absolute ground vibration displacement U and the absolute displacement X of the mass, can be detected by measuring this electrostatic capacitance C. The servo circuit 310 (indicated by the double-dotted line) is powered by a gain K. P The displacement amplifier 311 is constructed to amplify the aforementioned relative displacement signal UX.

[0019] The following uses mathematical formulas to explain the detection principle of the accelerometer. Let the mass of the mass body 302 be m, the spring constant of the mechanical spring 303 supporting the mass body be k, the attenuation coefficient of the attenuator 304 be c, and the driving force of the actuator 307 be F = A. f If i = 0, then the following equations of motion hold true.

[0020] [Mathematical Expression 1]

[0021]

[0022] Through the proportional gain constant K P An amplifier is used to control the current i0 of the actuator so that the relative displacement ux is zero.

[0023] [Mathematical Expression 2]

[0024] A f i0 = K P (ux) …(2)

[0025] [Mathematical Expression 3]

[0026]

[0027] If the proportional gain constant K P If it is large enough, then compared with the third term on the right side of equation (3), the first and second terms can be ignored.

[0028] [Mathematical Expression 4]

[0029]

[0030] If the current i0 flowing through the actuator is detected according to equations (2) and (4), the acceleration of the mass 302 can be approximately calculated.

[0031] 5. The specific structure of existing servo-type accelerometers

[0032] Servo-type accelerometers can be broadly categorized into two types: (1) those using linear motion of the mass unit, and (2) those using oscillating motion of the mass unit. Examples of these two existing sensors will be described below.

[0033] (5-1)...Existing examples of linear motion acceleration sensors

[0034] Figure 54 This is a front sectional view showing a specific structural example of a conventional linear motion accelerometer. The basic principle of linear motion is disclosed in Patent Document 1. Figure 53 The basic structure and detection principle shown are as follows: 11 is a permanent magnet, 12 is a pole piece, 13 is a pole piece protrusion, 14 is a permanent magnet-side yoke, 15 is a coil-side yoke, 16a is a force-applying coil, 16b is a detection coil, 17 is a coil frame, 18 and 19 are coil frame support members made of non-magnetic and non-conductive materials, 20 is a front disc spring, 21 is a rear disc spring, 22 is the front connecting structure between the front disc spring 20 and the coil-side yoke 15, and 23 is the rear connecting structure between the rear disc spring 21 and the coil-side yoke 15.

[0035] 24 is a movable side electrode, 25 is a fixed side electrode, 26 is a front panel, 27 is a central plate, and 28 is a fastening component for the fixed side electrode 25 and the front panel 26.

[0036] A radially oriented magnetic gap 29 is formed between the outer periphery of the electrode portion 12 and the inner periphery of the coil-side yoke 15. 29a is the permanent magnet-side gap, and 29b is the yoke-side gap. A closed-loop magnetic circuit is formed by "permanent magnet 11 → electrode portion 12 → magnetic gap 29 → coil-side yoke 15 → permanent magnet-side yoke 14". If current flows through the force-applying coil 16a disposed in the space of the magnetic gap 29, a Lorentz force is generated that causes the movable side electrode 24 to move axially. 30 is the gap formed by the movable side electrode 24 and the fixed side electrode 25. Since the electrostatic capacitance C is determined by the size of the gap in the gap 30, the relative displacement UX, which is the difference between the absolute displacement U of the ground vibration and the absolute displacement X of the mass body, can be detected by measuring the electrostatic capacitance C. The servo circuit consists of a displacement detector 31, an amplifier 32, and a driver 33. The amplifier 32 and the driver 33 are at a gain K. P A displacement amplifier that amplifies the relative displacement signal UX. This is achieved through a proportional gain constant K. P An amplifier is used to control the current i0 of the actuator so that the relative displacement ux is zero. If the current i0 flowing through the force coil 16a is detected, the acceleration acting on the movable part can be calculated as described above.

[0037] (5-2)...Existing examples of oscillating motion acceleration sensors

[0038] (1) Overall structure of the sensor Figure 56 This is a front sectional view showing an example of the oscillating motion disclosed in Patent Document 2. 590a is an oscillator located within a circular plate-shaped frame 590. The oscillator 590a is formed as a tongue shape with a portion of its circumference removed, and is supported by the frame 590 via a hinge 590b. The frame 590, oscillator 590a, and hinge 590b are, for example, integrally formed from quartz glass. The hinge 590b is thin-walled and elastically deformable, allowing the oscillator 590a to displace in the vertical direction within the same figure by inputting acceleration.

[0039] 591 and 592 are a pair of magnetic yokes, 593 is the bottom of the pole piece, 594 is a permanent magnet, and 595 is the top of the pole piece. The permanent magnet 594 is magnetized in its thickness direction, and annular magnetic gaps 596 are formed between the inner circumferential surfaces of the open ends of the magnetic yokes 591 and 592 and the outer circumferential surfaces of the top of the pole piece 595. Coil frames 598, with torque coils 597 wound within these annular magnetic gaps 596, are respectively mounted on the two plates of the oscillator 590a.

[0040] Electrostatic capacitor electrodes 590c are formed in an arc shape on the outer periphery of the front end side of the tongue-shaped plate on the two plates of the oscillator 590a. 591e and 592e are electrode surfaces that are opposite to the electrostatic capacitor electrodes 590c at a predetermined interval.

[0041] In this servo-type accelerometer with this structure, the displacement of the oscillator 590a caused by the acceleration input is detected as the change in electrostatic capacitance between the electrostatic capacitance electrode 590c and the electrode surfaces 591e and 592e. The electrode surfaces 591e and 592e share a common potential. The detection signal from the electrostatic capacitance electrode 590c on the two surfaces of the oscillator 590a is differentially amplified by a servo amplifier (not shown), and a torque current based on the electrostatic capacitance difference flows through a pair of torque coils 597. Through the interaction of this torque current with the magnetic field generated by the permanent magnet 594, the displaced oscillator 590a returns to its original shape and reaches equilibrium at the neutral point. The torque current at this point is proportional to the acceleration applied to the oscillator 590a, and therefore the input acceleration is calculated from this current. The coil ends 597a and 597b of the torque coils 597 are electrically connected to a metal conductor (not shown) on the oscillator 590a.

[0042] (2) Structure of the oscillator

[0043] Figure 58 This is a top view of the oscillator 590a. Figure 58 (a) is a face. Figure 58 (b) is the other side. The frame 590, oscillator 590a, hinges 590b1 and 590b2 are formed, for example, from a circular plate of quartz glass by etching. The oscillator conductor A is formed in an arc shape on one side of the frame 590, approximately half the width of the frame 590. One end of the arc-shaped metal conductor extends along the extension direction of a hinge 590b1, and after passing the center of the oscillator 590a, it is formed into a hook-shaped shape that bends back towards its center. The arc-shaped oscillator conductor A constitutes an input / output terminal for the torque current.

[0044] The oscillator conductor B is formed on one surface, starting from the end of the oscillator conductor A located at the center of the oscillator 590a, sandwiching the center of the oscillator 590a, and extending towards the outer edge of the oscillator 10a at a distance approximately equal to the spacing between the skeleton conductors described later, with the same width as the oscillator conductor A. Furthermore, the oscillator conductor B is continuously formed along the side of the outer edge of the oscillator 590a to another surface at a position between a pair of hinges 590b1 and 590b2. The shape of the oscillator conductor B on the other surface is the same as the shape on the first surface. The oscillator conductor B connects the left and right torque coils 597 in series.

[0045] The oscillator conductor C is formed on another surface with a shape substantially the same as that of the oscillator conductor A described above. The end of the oscillator conductor C is formed in an arc shape on one side of the frame 590 with a width substantially equal to that of the frame 590. The end of the oscillator conductor C on one surface and the oscillator conductor C on the other surface are continuously formed along the inner diameter side of the frame 590. The arc-shaped oscillator conductor C constitutes another input / output terminal for the torque current.

[0046] The electrostatic capacitance detection electrode D is formed in an arc shape on one surface of the oscillator 590a along the outer edge of the oscillator 590a, and further along the hinge 590b2, and on the frame 590, an end is formed in an arc shape along the outer periphery of the frame 590 with a width approximately half the width of the frame 590.

[0047] Furthermore, the electrostatic capacitance detection electrode E is formed on another surface of the oscillator 590a in the same manner as the electrostatic capacitance detection electrode D. Additionally, the electrostatic capacitance detection electrode E extends along the inner diameter side of the frame 590 to one surface of the frame 590, and an end is formed in an arc shape on one surface of the frame 590 with a width approximately equal to that of the frame 10. The ends of the electrostatic capacitance detection electrodes D and E on one surface of the frame 590 are each connected to a servo amplifier (not shown).

[0048] As described above, each oscillator conductor is formed by sputtering or vacuum evaporating a thin film of gold (Au) onto the surfaces of the frame 590, oscillator 590a, hinges 590b1, and 590b2, which are made of quartz glass.

[0049] In the aforementioned linear motion accelerometer and oscillating motion accelerometer, the differences in their basic structures can be classified based on the elastic support method of the movable part. The linear motion type uses the direction of movement of the movable part as the axis, with a spring arranged circumferentially around this axis. The oscillating motion type uses a cantilever beam with one end fixed and the other free to support the movable part.

[0050] Existing technical documents

[0051] Patent Document 1: Japanese Patent Publication No. 2004-205284

[0052] Patent Document 2: Japanese Patent Publication No. 2010-96509

[0053] Patent Document 3: Japanese Patent Publication No. 2006-283966

[0054] In the case of the linear motion acceleration sensor disclosed in Patent Document 1, there are significant challenges in manufacturing technology due to the basic operating principle / structure. Figure 55 (a) is a front view showing the shape of the front disc spring 20. Figure 55 (b) is from the overall sensor diagram above. Figure 54 The front sectional view of the front panel 26, fixed side electrode 25, etc. was removed from the image. Figure 55 (c) is Figure 55 The enlarged view of part A in (b) is a diagram showing the state of the movable side electrode 24 after axial deformation.

[0055] To connect the terminals of the force coil 16a and the detection coil 16b to the externally located control circuit, four conductive paths are required. Furthermore, if the movable side electrode 24 and the displacement detector 31 are included... Figure 54 The conduction path requires a total of five independent conduction paths. Since the two coils and the movable side electrode move axially, it is not possible to connect the five terminals to the external fixing part using wires. Therefore, as... Figure 55 of (a), Figure 55 As shown in (c), the five conduction paths are formed by the front disc spring 20 and the rear disc spring 21. That is, the two disc springs 20 and 21 are formed to serve as elastic supports for the movable parts (coil frame 17, movable side electrode 24, etc.) and the five independent conduction paths.

[0056] exist Figure 55 In (a), 34a, 34b, and 34c are the outer peripheral fixing portions of the front disc spring 20. As shown by the dashed circle AA, these three outer peripheral fixing portions are cut off at three points in the circumferential direction to achieve electrical insulation. 35a, 35b, and 35c are the inner peripheral spring portions of the front disc spring. As shown by the dashed circle BB, these three inner peripheral spring portions are cut off at three points in the circumferential direction to achieve electrical insulation. 36a, 36b, and 36c are welding portions used to make each coil terminal conductive to the inner peripheral spring portions. Figure 55 In (c), it is shown that the terminals of the calibration coil 16b are connected to the inner circumferential spring portion 35c by means of the welding portion 36c. Furthermore, the coil wire diameter used for the servo-type accelerometer is, for example, an extremely fine wire of about 30 μm.

[0057] In other words, as a production technology issue arising from the basic operating principle / structure, existing servo-type accelerometers require a "cutting / insulating / welding" process between the disc spring and the coil. This complex process is a major cause of reduced yield and reliability during mass production. Considering long-term reliability, the small-diameter disc spring used in linear motion accelerometers must be made of metal. The rationale is that, from a sensor performance perspective, the mechanical resonant frequency, determined by the inertial mass of the movable part and the spring stiffness, needs to be sufficiently low, necessitating a relatively small spring stiffness value. Small-diameter disc springs deform significantly under relatively small external forces. Therefore, it is difficult to employ a structure that combines non-metallic materials (e.g., quartz glass) and conductive films (conduction paths) used in oscillating motion accelerometers.

[0058] The reason why the existing oscillating motion accelerometer disclosed in Patent Document 2 uses a thin-film processing method that requires expensive processing equipment such as sputtering and vacuum evaporation is that it requires the following (i) and (ii): (i) a conduction path connecting a pair of torque coils of the oscillating motion and an external control circuit, and (ii) a conduction path connecting an electrostatic capacitor electrode formed on the surface of the oscillator 590a of the oscillating motion and an external control circuit. The aforementioned multiple independent conduction paths utilize elastically deformable thin-walled hinges 590b1 and 590b2 to form a thin film on their surface. Figure 57 The magnified representation shows the oscillator 590a in the state of oscillation.

[0059] Besides this method, for example, one could envision connecting multiple thin wires (metal wires) to the moving member side and the fixed member side via welding or conductive adhesive. In this case, the spring load accompanying the deformation of the metal wires is applied in parallel with the spring stiffness of the hinge portion, affecting the mechanical resonant frequency. Furthermore, a decrease in reliability, such as fatigue failure caused by repeated stress applied to the metal wires, cannot be avoided.

[0060] Therefore, in any servo-type accelerometer, whether linear or oscillating, the conduction path for multiple signals flowing between the movable and fixed sides must be formed using an elastic member connecting the two. As a result, the increased cost due to the required complex structure and manufacturing methods becomes a major reason for reduced yield and reliability in mass production.

[0061] As an example of an active vibration damping table, consider a four-point support active control system. In this case, actuators are positioned at the four corners, with two actuators facing diagonally in the horizontal X direction and two in the Y direction. Furthermore, each actuator also includes an actuator supporting the load in the Z direction. This results in a total of eight actuators, requiring eight acceleration sensors for controlling each actuator. Additionally, if sensors for detecting ground acceleration are included, a total of nine costly acceleration sensors are needed. Therefore, in the case of a multi-axis controlled active vibration damping table, the large number of required acceleration sensors presents a serious problem of a high overall cost ratio.

[0062] As mentioned above, the difficulty of wiring processing, which is the main reason for the reduced yield, is an unavoidable problem in the moving / coil type (MC type) due to the movement of the coil in the movable part. This invention returns to the origin of this problem, focusing on the actuator section of a servo-type accelerometer, which forms a closed-loop magnetic circuit with three elements: a permanent magnet, a coil, and a yoke. If the coil, one of these three elements, is fixed, the inherent problem of the moving / coil type (MC type), namely the difficulty of wiring processing, which is the main reason for the reduced yield, is solved in one fell swoop. Summary of the Invention

[0063] Furthermore, the servo-type vibration detector of claim 1 includes: a fixed member; a movable member configured to move relative to the fixed member in a predetermined direction, wherein magnetic flux flows internally; an elastic member supporting the movable member and disposed relative to the fixed member with a gap; a displacement detection unit for detecting the displacement of the movable member in the predetermined direction; and a drive unit that, upon detecting a relative displacement of the movable member from its origin position by the displacement detection unit, generates an electromagnetic force that returns the movable member to its origin position, the drive unit comprising a coil fixed to the fixed member, and the movable member comprising at least a movable side yoke forming part of a closed-loop magnetic circuit.

[0064] In other words, this invention fixes a coil to the side of a fixed member and arranges a permanent magnet such that magnetic flux flows through the gap between the fixed member and the movable member. The movable member is composed of the permanent magnet and a yoke, or only the yoke. The movable member is driven by an electromagnetic force generated by forming a closed-loop magnetic circuit. According to this invention, complex wiring for moving / coil circuits is eliminated in the production process, significantly simplifying mass production methods and reducing production costs.

[0065] In the servo-type vibration detector of claim 2, the movable member further comprises a permanent magnet forming the closed-loop magnetic circuit, the movable side magnetic yoke is connected to any one of the magnetic pole faces of the permanent magnet, and the movable side magnetic yoke is disposed within the coil, and the driving unit is configured to move the permanent magnet and the movable side magnetic yoke in the predetermined direction by applying current to the coil and utilizing the reaction force of the Lorentz force experienced by the current-flowing conductor in the magnetic field.

[0066] That is, in this invention, if current flows through a conductor placed in a magnetic field, a Lorentz force as an electromagnetic force is generated in the conductor. Regardless of the type of actuator and its driving principle, the force relationship between the stationary and moving sides is relative. Specifically, in this invention, if current flows through the coil in a fixed configuration, the reaction force of the Lorentz force that causes the permanent magnet to move axially is utilized.

[0067] The servo-type vibration detector of claim 3 further comprises a permanent magnet fixed to the fixed member and forming the closed-loop magnetic circuit, the movable side magnetic yoke being disposed away from any one of the magnetic pole faces of the permanent magnet, and the movable side magnetic yoke being disposed within the coil, the drive unit being configured to move the movable side magnetic yoke in the predetermined direction by applying current to the coil and utilizing the reaction force of the Lorentz force experienced by the current-flowing conductor in the magnetic field.

[0068] That is, in this invention, not only is the coil fixed but also the permanent magnet fixed, and by moving only the yoke, an actuator for a servo-type accelerometer is constructed. That is, it should also be referred to as a "third linear motor," proposing a moving / yoke type (MY type (provisional name)) scheme. The MY type accelerometer is characterized by...

[0069] (1) Similar to the MC type, it achieves lightweighting of the movable part.

[0070] (2) Like the MM type, it does not require the processing of extremely fine wires with coils.

[0071] That is, it can eliminate the disadvantages of both MM and MC types, and combine the advantages of both.

[0072] In the servo-type vibration detector of claim 4, the displacement detection unit includes: a movable side electrode disposed on the movable member; and a fixed side electrode fixed to the fixed member in a manner opposite to the movable side electrode, configured to detect the displacement of the movable member based on the change in electrostatic capacitance formed between the movable side electrode and the fixed side electrode.

[0073] That is, in this invention, a high-resolution servo-type accelerometer can be realized by applying an electrostatic capacitive type that can achieve the highest detection accuracy among various sensors.

[0074] In the servo-type vibration detector of claim 5, the gap portion includes a first gap portion and a second gap portion forming a radial gap between the movable member and the fixed member within the closed-loop magnetic circuit. The first gap portion is fixedly configured with a coil for generating the Lorentz force, and the second gap portion is a magnetic connection portion for allowing magnetic flux to flow between the movable member and the fixed member.

[0075] That is, in this invention, in the existing MC type, only one gap is needed to form a closed-loop magnetic circuit. In contrast, in the MM or MY type of this invention, two gaps are required to form a closed-loop magnetic circuit. By providing a secondary gap (second gap) as a "magnetic connection" relative to the main gap (first gap) separating the coil, the coil can be fixedly mounted in a magnetic field with high magnetic flux density, and the coil can generate a Lorentz force.

[0076] In the servo-type vibration detector of claim 6, a pole piece connected to any one of the magnetic pole faces of the permanent magnet and forming part of a movable side magnetic yoke, a coil fixedly disposed on the fixing member with the radially opposite face of the pole piece or the permanent magnet separated by the first gap, and a magnetic connection part configured to allow magnetic flux to flow between the other magnetic pole face of the permanent magnet and the fixing member, wherein the permanent magnet, the pole piece, the first gap, the fixing member, and the magnetic connection part form a closed-loop magnetic circuit.

[0077] That is, in this invention, a magnetic connection portion is provided such that magnetic flux flows between the other magnetic pole face of the permanent magnet, which is a movable member, and the fixed member. Through this magnetic connection portion, the permanent magnet, the pole portion, the gap portion, and the fixed member, a closed-loop magnetic circuit for driving the pole portion using Lorentz force is formed.

[0078] The servo-type vibration detector of claim 7 includes a pole piece that forms part of a movable side magnetic yoke, and a coil that is fixedly disposed in the fixed member within the gap between the pole piece and the fixed member. The pole piece and any one magnetic pole face of the permanent magnet are disposed across the magnetic connection portion. The permanent magnet is fixedly disposed such that magnetic flux flows between the other magnetic pole face of the permanent magnet and the fixed member, and a closed-loop magnetic circuit is formed by the permanent magnet, the magnetic connection portion, the pole piece, and the fixed member.

[0079] That is, in this invention, a magnetic pole face of a permanent magnet, which is a fixed member, forms a magnetic circuit with a pole piece via a magnetic connection part, which is a movable member, and a magnetic pole face of the permanent magnet and the fixed member form a closed-loop magnetic circuit in a manner of magnetic flux flow.

[0080] In the servo-type vibration detector of claim 8, the electrode portion is configured in a generally cylindrical shape.

[0081] That is, the present invention has found that by making the electrode portion cylindrical and making the thickness of the cylindrical portion thin and long, the following effects are obtained.

[0082] (1) It can increase the force constant (electrical / mechanical conversion efficiency) of the voice coil motor.

[0083] (2) It can reduce the increase in the inertial mass of the movable part.

[0084] (3) Even if the number of coil turns is increased to increase the generating force, the heat generation can be suppressed.

[0085] As discovered in (1) above, by lengthening the electrode portion, the influence of leakage flux on the generated force can be reduced. In (2) above, even if the electrode portion is lengthened, the increase in mass is minimal if the thickness of the cylindrical portion is thin. In (3) above, by lengthening the electrode portion, the coil storage space on its opposite side can be increased. That is, by increasing the coil wire diameter, the increase in coil resistance accompanying the increase in the number of coil turns is suppressed. Therefore, by (1) to (3) above, the problem of increased mass (UP) of the movable part caused by replacing the MC type with the MM type is solved. According to the present invention, it is possible to obtain an MM type accelerometer with signal transmission characteristics and high responsiveness that extends to the high-frequency region (e.g., 400 to 500 Hz and above).

[0086] In the servo-type vibration detector of claim 9, it comprises a permanent magnet magnetized in the axial direction, a pole piece connected to one magnetic pole face of the permanent magnet, a coil fixedly disposed on the inner surface of the housing with the radially opposite face of the pole piece separated by a gap, and a magnetic connection portion configured to allow magnetic flux to flow between the other magnetic pole face of the permanent magnet and the housing.

[0087] That is, in this invention, by connecting the permanent magnet that is magnetized in the axial direction and the pole piece, a servo-type accelerometer can be realized with a simple component structure.

[0088] In the servo-type vibration detector of claim 10, the radial distances between the movable member in the first gap and the fixed member in the second gap are set as δ1 and δ2, respectively, where δ1 > δ2.

[0089] That is, in this invention, by making the gap (secondary gap) of the magnetic connection part narrower than the void part (main gap part), the magnetic resistance of the magnetic connection part is smaller than the magnetic resistance of the void part, thereby reducing the influence of the magnetic connection part on the generated force.

[0090] In the servo-type vibration detector of claim 11, the mass of the movable part including the movable side magnetic material component is set as m, and the mass of the permanent magnet is set as m p The lower limit value m of the mass of the movable part min =2m p The sensitivity K of the position sensor will be determined. S Adjusting the gain K C , proportional gain K P The electrical gain determined by the product is set as K. PT Set the force constant of the actuator to K. t Let the resistance of the coil be R. a K T =K PT Kt / R a The resonant frequency required by the accelerometer is set to f0, and the upper limit value of the mass of the movable part is m. max =K T / (2πf0) 2 When, set to m min ≤m≤m max The range.

[0091] That is, in this invention, the lower limit of the mass m of the movable part of the MM-type accelerometer is considered, with the mass m of the permanent magnet as the reference. p Based on this, by studying the shape of the magnetic material component (pole portion) connected to the permanent magnet, it is possible to obtain the force generated by existing MC-type or higher actuators, and to make the lower limit value m of the movable part mass m possible. min =2m p Furthermore, the upper limit of the mass m of the movable part is... max The resonant frequency f0 required by the accelerometer and the electrical gain K of the control circuit. PT The force constant K of the actuator t The resistance R of the coil a Sure.

[0092] In the servo-type vibration detector of claim 12, the magnetic connection part is composed of an auxiliary permanent magnet that is magnetized in the radial direction and an auxiliary coil that is fixedly disposed on the inner surface of the housing with a gap between the surfaces opposite to the auxiliary permanent magnet in the radial direction.

[0093] That is, in this invention, the magnetic connection portion is composed of an auxiliary permanent magnet magnetized in the radial direction and an auxiliary coil disposed on its opposite side. According to this structure, the magnetic connection portion functions as a secondary actuator, thus increasing the generating force of the drive unit. Furthermore, the air gap between the auxiliary permanent magnet and the auxiliary coil can be set sufficiently large, thus facilitating assembly. Even when the shaft of the movable part is eccentric relative to the fixed side, the generating force applied to the movable part in the radial direction is also very small.

[0094] In the servo-type vibration detector of claim 13, a first transmission part and a second transmission part are provided in the closed-loop magnetic circuit to transmit magnetic flux in the radial direction between the movable member and the fixed member. The first transmission part has a radial gap between the movable member and the fixed member, and the coil for generating the Lorentz force is fixedly disposed in the gap. The second transmission part fixes the movable member and the fixed member with a disc-shaped spring made of magnetic material in which magnetic flux flows in the radial direction. The disc-shaped spring also serves as the elastic member supporting the movable member.

[0095] That is, in this invention, the first transmission part is not treated as a gap, but rather as a magnetic circuit formed by the disc spring made of magnetic material itself, creating a closed-loop magnetic circuit. According to this embodiment, which eliminates the need for a magnetic connection part, a servo-type accelerometer can be implemented with a simple structure.

[0096] In the servo-type vibration detector of claim 14, the permanent magnet is used as the front permanent magnet, the coil is used as the front coil, and the magnetic connection part is composed of a rear permanent magnet that is magnetized in the radial direction, a pole piece connected to one magnetic pole surface of the rear permanent magnet, and a rear coil that is fixedly disposed on the inner surface of the housing across the gap on the radially opposite surface of the other magnetic pole surface of the rear permanent magnet. The front permanent magnet, the gap, the housing, the gap, the rear permanent magnet, and the pole piece form a closed-loop magnetic circuit.

[0097] That is, in this invention, the front permanent magnet is composed of a radially magnetized magnet, and the magnetic connection portion is composed of a radially magnetized magnet and a fixed coil. Since both the front and rear sides function as voice coil motors, the generated force is improved. Furthermore, by significantly increasing the radial gap between the coil mounting portion and the two permanent magnets, for example, it can be configured to be approximately δ = 0.5 mm. Compared to the above embodiment where a narrow gap forms an annular void, assembly during mass production is also easier.

[0098] In the servo-type vibration detector of claim 15, the elastic member is made of a conductive material in the shape of a generally flat circular ring, and at least the outer peripheral side of the elastic member is sandwiched with a non-conductive material and fixed to the fixing member.

[0099] That is, in this invention, the elastic member (disc spring) serves as a conductive path connecting the movable side electrode and the outside, and is electrically insulated relative to the fixed side supporting the elastic member. Therefore, it is possible to detect minute electrostatic capacitance signals between the fixed side electrode and the movable side electrode without being affected by interference noise.

[0100] In the servo-type vibration detector of claim 16, a non-conductive material is sandwiched between the movable side electrode and the electrode portion.

[0101] That is, in this invention, eddy currents are generated on the surface of the electrode, but since the movable side electrode is electrically insulated from the electrode, the electrostatic capacitance signal can avoid the influence of the eddy currents.

[0102] The servo-type vibration detector of claim 17 includes movable side electrode members respectively disposed on two end faces of the movable member, and fixed side electrode members disposed opposite to these movable side electrode members on the fixed member. A differential sensor is constructed by detecting the output difference of two sets of electrostatic capacitance sensors formed between the electrode surfaces of the movable side electrode members and the fixed side electrode members.

[0103] That is, in this invention, we focus on the structural features of a linear motion type MM or MY where both the left and right output shafts are open ends, and construct a differential electrostatic capacitive sensor by setting the electrodes for detecting electrostatic capacitance in the left and right parts.

[0104] The servo-type vibration detector of claim 18 is characterized in that, at one side shaft end of the movable member, two plate-shaped movable side electrode members are disposed with a gap between them, and a plate-shaped fixed side electrode member is disposed within the gap in such a way that it is clamped by the two movable side electrode members. A first electrostatic capacitance sensor is formed between the electrode surface Sa of the movable side electrode member and the electrode surface SA of the opposite fixed side electrode member, and a second electrostatic capacitance sensor is formed between the electrode surface SB on the back side of the electrode surface SA and the electrode surface Sb of the opposite movable side member.

[0105] That is, in this invention, two sets of electrostatic capacitive sensors are formed by two movable side electrodes and one fixed side electrode disposed on one side of the movable part's shaft end. It can also be applied to acceleration sensors with actuators capable of utilizing only one side of the shaft's main shaft end.

[0106] In the servo-type vibration detector of claim 19, a plate-shaped movable side electrode member is provided at the end of the movable member. Electrode surfaces SAA and SBB are formed on the surface and back of the movable side electrode member. Two plate-shaped fixed side electrode members are arranged to clamp the movable side electrode member with a gap. A first electrostatic capacitance sensor is formed between the electrode surface SAA and the electrode surface Saa of the opposite fixed side electrode member, and a second electrostatic capacitance sensor is formed between the electrode surface SBB and the electrode surface Sbb of the opposite fixed side electrode member.

[0107] That is, in this invention, two sets of electrostatic capacitive sensors are formed by a movable side electrode and two fixed side electrodes disposed on one side of the movable part's shaft end. Similar to the above embodiment, this can also be applied to an acceleration sensor having an actuator capable of utilizing only one side of the shaft's main drive end.

[0108] In the servo-type vibration detector of claim 20, the coil is housed in a non-magnetic metal frame, and the metal frame is fitted into the inner surface of the hollow cylindrical portion of the fixing member.

[0109] That is, the coil frame is made of a non-magnetic material with good thermal conductivity (e.g., aluminum), and the coil frame is tightly mounted to the inner surface of the housing. As a result, the heat generated by the coil can be easily dissipated, thus reducing sensor noise associated with thermal noise. In the case of existing MC-type sensors, the coil frame and coil are arranged in a suspended state. The components supporting the coil frame are made of non-magnetic and non-conductive materials, so heat dissipation based on thermal conduction of the coil cannot be expected. This invention utilizes the structural features of the MM-type design, which allows the coil to be fixed in place.

[0110] In the servo-type vibration detector of claim 21, a recess is formed on the inner surface of the housing near the axial end face of the coil that is in close contact with the inner surface of the fixed member, such that the radial distance between the movable member and the fixed member is greater than that between the two ends.

[0111] That is, in this invention, attention is paid to the fact that the magnetic flux flowing vertically in the magnetic gap effectively contributes to the generation of force by the actuator. In contrast, the magnetic flux flowing from the corner of the opposite surface of the coil to the corner of the inner peripheral surface of the coil-side yoke is leakage flux and does not contribute to the generation of force. The recess formed in the coil-side yoke makes a significant contribution to reducing leakage flux.

[0112] In the servo-type vibration detector of claim 22, at least one of the permanent magnet and the pole piece, the coil frame housing the coil and the fixing member, the elastic member and the fixing member, or the elastic member and the pole piece is fastened by bolts of M0.5 to M1.0 mm.

[0113] That is, in this invention, an extremely small bolt fastening method with diameters of M0.5 to M1.0 mm, used in specialized fields such as watches, is applied to an accelerometer composed of tiny components. The reason for applying the extremely small bolt fastening method is that it addresses the MM-type characteristics of components that do not require extremely fine wire processing and simplify the structure of the movable parts.

[0114] In existing accelerometer sensors constructed using adhesive bonding methods, defective products must be discarded during quality evaluation in mass production. In the sensor of this invention, multiple components can be reused, significantly improving the yield rate in mass production. Furthermore, in adhesive bonding methods, the thickness and unevenness of the adhesive between the bonded components contribute to reduced assembly accuracy. In the present invention, high assembly accuracy can be ensured as long as the machining accuracy of each component is achieved. Moreover, operator skill is not required, thus reducing deviations in product performance.

[0115] In the servo-type vibration detector of claim 23, the elastic member is formed of a disk-shaped conductive material, and the inner and outer peripheries of the elastic member are integrated with a thin plate member made of a non-conductive material.

[0116] In other words, this invention combines the advantages of both adhesive bonding and bolt fastening methods. For example, during the assembly preparation stage, components requiring electrical insulation are pre-integrated with conductive materials (metals) and insulating materials (ceramics, etc.) using an adhesive. Once this process is completed, the bolt fastening method can be applied, enabling efficient production with a simple structure.

[0117] The servo-type vibration detector of claim 24 further includes: a movable unit, including at least the movable member, and equipped with a movable side electrode; and a fixed unit, equipped with a fixed side electrode configured to face the movable side electrode, the displacement detection unit being configured to detect the electrostatic capacitance formed between the movable side electrode and the fixed side electrode, an interlocking structure being formed between the movable unit and the fixed unit, the movable unit and the fixed unit being able to move axially relative to each other while restricting the relative radial movement of the movable unit and the fixed unit, and grooves for bonding and fixing the movable unit and the fixed unit being formed on the outer surfaces of the movable unit and the fixed unit.

[0118] That is, according to the application of the present invention, by applying an adhesive method in the final assembly stage, the gap between the electrodes on the movable and fixed sides can be adjusted to an optimal value while simultaneously measuring the electrostatic capacitance. According to this method, all accumulated errors can be absorbed in the final process. For example, the two units can be secured by curing the UV-curable adhesive by irradiating it with LED light when the electrostatic capacitance reaches the target value.

[0119] In the servo-type vibration detector of claim 25, the invention includes the fixing member, the bolt, and the elastic member, which are made of conductive material. The elastic member is bonded to a thin plate made of a non-conductive member, which is bolted to the fixing member. The bolt head is configured to be in non-electrical contact with the elastic member.

[0120] That is, in this invention, the elastic member (disc) is used as a conduction path for the electrostatic capacitance signal between electrodes, and the elastic member is fastened to the housing in a non-electrical contact manner using metal bolts and non-conductive components (e.g., ceramics). According to this method, it is unaffected by interference noise and can transmit minute electrostatic capacitance signals.

[0121] In the servo-type vibration detector of claim 26, the elastic member is composed of a cantilever beam with one end as a fixed end and the other end as a free end, and the movable member is provided on the free end side of the cantilever beam.

[0122] That is, in this invention, a cantilever beam (oscillator structure) with one end as a fixed end and the other end as a free end is used in the elastic member. With the cantilever beam structure, low-rigidity support can be achieved with a simple structure, thus allowing the resonant frequency (natural value) of the movable part to be set sufficiently small.

[0123] In the servo-type vibration detector of claim 27, a portion of the cantilever beam is used as a conductive material, serving as a signal transmission path that connects the signal from the displacement detection unit to the fixed member side.

[0124] That is, in this invention, the MM type with a fixed coil is utilized, taking advantage of the fact that the electrical signal drawn from the movable side of the oscillating motion is only one electrostatic capacitance signal. In the case of the MC type with a moving coil, multiple signal transmission paths are formed using thin-film forming technology in a cantilever beam made of a non-conductive material such as quartz glass. In the case of the sensor of this invention, conductive (metallic) materials can be applied in the cantilever beam.

[0125] In the servo-type vibration detector of claim 28, the radial stiffness of the elastic member in the magnetic connection is set to K. r The eccentricity of the axis of the movable magnetic material component relative to the axis of the fixed magnetic material component is set as δ. r Let F be the radial force generated by the magnetic attraction at that time. r Define the negative spring stiffness K mr =F r / δ r , constitutes K r >K mr .

[0126] That is, in this invention, when the component accuracy and assembly accuracy cannot be fully obtained in the magnetic connection part, and the shaft cores on the fixed side and the movable side are eccentric, a centrifugal magnetic attraction F is generated. r The negative spring stiffness K, formed by the magnetic circuit, is... mr =F r / δ r As long as the disk specification is selected so that the centripetal rigidity of the disk is K, r >K mr The magnetic connector can then maintain a stable state.

[0127] In the servo-type vibration detector of the invention of claim 29, the magnetic connection portion constitutes a MY-type accelerometer by the permanent magnet that is magnetized in the radial direction and the outer peripheral surface of the pole piece that is configured with a gap from the inner peripheral surface of the permanent magnet.

[0128] That is, in this invention, a magnetic circuit is constructed using multiple segmented permanent magnets magnetized in the radial direction. Therefore, when no current is applied to the force-applying coil, no axial electromagnetic force is generated in the pole portion, and the pole portion can be held in the same position.

[0129] In the servo-type vibration detector of claim 30, the magnetic connection portion is composed of the permanent magnet magnetized in the axial direction, a pole-side magnetic yoke connected to either the N pole or the S pole of the permanent magnet, and an inner peripheral surface of the pole portion that is configured with a radial gap relative to the outer peripheral surface of the pole-side magnetic yoke.

[0130] That is, in this invention, a magnetic circuit is constructed using permanent magnets magnetized in the axial direction. The magnetic circuit can be easily constructed, and the performance of the permanent magnets can be selected over a wide range. Since the size / shape of the permanent magnets is not limited, the demagnetization characteristics (holding force H), which are indicators of the permanent magnet's performance, can be selected over a wide range. c saturation magnetic flux density B r Because permanent magnets have a performance margin, the gap in the magnetic connection can also be large enough. This gap becomes magnetic reluctance, but it is possible to obtain permanent magnet performance sufficient to compensate for its losses.

[0131] The servo-type vibration detector of claim 31 comprises: a fixed member; a movable member configured to move relative to the fixed member in a predetermined direction, wherein magnetic flux flows within it; an elastic member supporting the movable member and disposed relative to the fixed member with a gap; a displacement detection unit for detecting displacement of the movable member in the predetermined direction; and a drive unit that, upon detecting relative displacement of the movable member from its origin position by the displacement detection unit, generates an electromagnetic force to return the movable member to its origin position, wherein the displacement detection unit includes a movable side electrode configuration. The device comprises a movable electrode member having two electrode surfaces disposed on the movable member, and a fixed electrode member having two electrode surfaces disposed on the fixed member. By arranging the electrode surfaces of the movable electrode member and the fixed electrode member opposite to each other, two sets of electrostatic capacitive sensors are formed. The movable electrode member and the fixed electrode member are configured to move in a predetermined direction according to the movable member, causing the gap between the electrode surfaces of the two sets of electrostatic capacitive sensors to change in opposite phase. By taking the difference between the output signals of the two sets of electrostatic capacitive sensors, a differential sensor is formed.

[0132] That is, in this invention, by using the accelerometer as a differential sensor, a high-sensitivity sensor can be realized whose output is not easily affected by interference signals such as noise and drift.

[0133] The absolute velocity and absolute displacement signals obtained by fully integrating the acceleration output of the sensor of the present invention are not prone to divergence. Therefore, when the sensor of the present invention is applied to an active vibration damping table, in addition to the effect of improved sensor sensitivity (e.g., improved positioning accuracy of the stage), a significant improvement in vibration damping characteristics in the low-frequency region is also obtained.

[0134] The vibration control device of claim 32 includes the servo-type vibration detector and control device of claim 31. In order to obtain vibration damping performance in the low frequency region, the control device uses an absolute velocity signal obtained by integrating the acceleration signal output by the servo-type vibration detector once, or an absolute displacement signal obtained by integrating twice, to implement absolute velocity feedback and / or absolute displacement feedback.

[0135] That is, in this invention, the noise and drift jointly applied to the two electrode outputs are eliminated by taking the difference between the two sets of electrode outputs with opposite phase changes in the gap.

[0136] As a result, the absolute velocity signal and absolute displacement signal, which are fully integrated over the acceleration output, do not diverge. When the accelerometer of this embodiment is applied to an active vibration damping table, in addition to the effect of improved sensor sensitivity (e.g., improved positioning accuracy of the stage), a significant improvement in vibration damping characteristics is also achieved in the low-frequency region.

[0137] The servo-type vibration detector of claim 33 comprises: a fixed member; a movable member configured to move relative to the fixed member in a predetermined direction, wherein magnetic flux flows within it; an elastic member supporting the movable member and disposed relative to the fixed member with a gap; a displacement detection unit for detecting the displacement of the movable member in the predetermined direction; and a drive unit that, upon detecting a relative displacement of the movable member from its origin position by the displacement detection unit, generates an electromagnetic force that returns the movable member to its origin position, comprising a through coil. An electromagnet is constructed by a fixed-side magnetic yoke and a movable-side magnetic yoke disposed with a gap between the open end of the fixed-side magnetic yoke and the movable-side magnetic yoke, forming a closed-loop magnetic circuit. This electromagnet serves as an attraction-generating unit A that attracts the movable member, including the movable-side magnetic yoke, toward the coil. An attraction-generating unit B, which generates a force in the opposite direction to attraction-generating unit A, is disposed with the movable member in between, and the current flowing through the coil is controlled. This constitutes a drive unit based on Maxwell stress that causes the movable member to move axially.

[0138] That is, in this invention, a magnetic attraction force generated by Maxwell stress is used to drive the movable part. When comparing actuators with the same external dimensions, the electromechanical conversion efficiency (thrust constant) of Maxwell stress relative to the force generated by the input current is overwhelmingly higher than that of Lorentz force, typically more than 20 times. By utilizing this, the accelerometer of this embodiment can significantly increase the upper limit of the measurable acceleration.

[0139] The servo-type vibration detector according to the present invention, since it is configured such that the yoke or permanent magnet can move while the coil is fixed, does not require the complex wiring of existing moving / coil-type servo-type vibration detectors, thus greatly simplifying the mass production method and reducing production costs. Attached Figure Description

[0140] Figure 1 This is a diagram illustrating the servo-type accelerometer sensor according to Embodiment 1 of the present invention. Figure 1 (a) is Figure 1 (b) AA direction view, Figure 1(b) is a front sectional view of the sensor body.

[0141] Figure 2 This is a model diagram of the magnetic circuit of the MM-type accelerometer of the present invention.

[0142] Figure 3 This is a model diagram of the magnetic circuit of an existing MC-type accelerometer.

[0143] Figure 4 It is a graph showing the analysis results of the relationship between the generated force F and the length L of the electrode section.

[0144] Figure 5 This is a graph showing the analytical results representing the relationship between the leakage coefficient σ and the electrode length L.

[0145] Figure 6 It is a graph representing the inertial mass m of the movable part relative to the length L of the electrode portion.

[0146] Figure 7 V represents the coil housing volume relative to the length L of the electrode section. C The curve graph.

[0147] Figure 8 This is a control block diagram of an accelerometer used for theoretical analysis.

[0148] Figure 9 The curves comparing the gain / phase characteristics of (1) to (3) are given that only the inertial mass m is 4 times in (1) the existing MC type, (2) the MM type of the present invention, and (3) the existing MC type specifications.

[0149] Figure 10 The graph compares the force generated by the actuator with respect to time with (1) the existing MC type and (2) the MM type of the present invention.

[0150] Figure 11 The graph compares the effect of mechanical noise on the sensor output with (1) the existing MC type and (2) the MM type of the present invention.

[0151] Figure 12 The curves of coil current were compared between (1) and (3) in the existing MC type, (2) the present invention MM type, and (3) the existing MC type, with only the inertial mass m being 4 times.

[0152] Figure 13 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 2 of the present invention.

[0153] Figure 14 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 3 of the present invention.

[0154] Figure 15 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 4 of the present invention.

[0155] Figure 16 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 5 of the present invention.

[0156] Figure 17 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 6 of the present invention.

[0157] Figure 18 The diagram shows the flow of magnetic flux in Implementation 6, indicated by arrows (dashed lines).

[0158] Figure 19 The diagram shows the flow of heat in Embodiment 6, indicated by arrows (dashed lines).

[0159] Figure 20 This is the servo-type accelerometer sensor of Embodiment 7 of the present invention. Figure 20 (a) is a front sectional view. Figure 20 (b) is Figure 20 AA section view of (a).

[0160] Figure 21 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 8 of the present invention.

[0161] Figure 22 This is the servo-type accelerometer sensor of Embodiment 9 of the present invention. Figure 22 (a) is a front sectional view. Figure 22 (b) and Figure 22 (c) is a cross-sectional view of a segmented permanent magnet.

[0162] Figure 23 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 10 of the present invention.

[0163] Figure 24 This diagram illustrates that the differential servo-type accelerometer of Embodiment 10 can be composed of three units.

[0164] Figure 25 This is a graph showing the relationship between electrode output, noise and drift, and sensor acceleration output in the case of existing accelerometers.

[0165] Figure 26 This is a graph showing the relationship between the output of the two electrodes, noise and drift, and the sensor acceleration output in the case of the accelerometer of Embodiment 10.

[0166] Figure 27This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 11 of the present invention.

[0167] Figure 28 This diagram illustrates the swing motion servo-type accelerometer sensor according to Embodiment 12 of the present invention. Figure 28 (a) is a front sectional view. Figure 28 (b) is a schematic view of the side of the oscillator, which is a component of the sensor.

[0168] Figure 29 This is a diagram illustrating an example of the assembly method of embodiment 12.

[0169] Figure 30 This is a front cross-sectional view of the swing motion servo-type accelerometer of Embodiment 13 of the present invention.

[0170] Figure 31 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 14 of the present invention.

[0171] Figure 32 This is a diagram showing step 1 of the assembly process in embodiment 14.

[0172] Figure 33 This is a diagram showing step 2 of the assembly process in embodiment 14.

[0173] Figure 34 This is a diagram showing step 3 of the assembly process in embodiment 14.

[0174] Figure 35 This is a diagram showing step 4 of the assembly process in embodiment 14.

[0175] Figure 36 This is a diagram showing step 5 of the assembly process in embodiment 14.

[0176] Figure 37 This is a diagram showing the spiral disk of embodiment 14.

[0177] Figure 38 This is a diagram showing step 6 of the assembly process in embodiment 14.

[0178] Figure 39 This is a diagram showing step 7 of the assembly process in embodiment 14.

[0179] Figure 40 This is a diagram showing step 8 of the assembly process in embodiment 14.

[0180] Figure 41This refers to the servo-type accelerometer sensor of Embodiment 15 of the present invention. Figure 41 (a) is a front sectional view of the fixed-side electrode unit. Figure 41 (b) is a front sectional view of the fixed-side electrode unit.

[0181] Figure 42 This is a front cross-sectional view showing the state in embodiment 15 where the two units are fastened together.

[0182] Figure 43 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 16 of the present invention.

[0183] Figure 44 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 17 of the present invention.

[0184] Figure 45 This refers to the servo-type accelerometer sensor of Embodiment 18 of the present invention. Figure 45 (a) is a diagram showing the shape of the front spiral disk. Figure 45 (b) is a front cross-sectional view of the accelerometer sensor. Figure 45 (c) is a diagram showing the shape of the rear disc.

[0185] Figure 46 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 19 of the present invention.

[0186] Figure 47 This refers to the servo-type accelerometer sensor of Embodiment 20 of the present invention. Figure 47 (a) is a front sectional view. Figure 47 (b) is Figure 47 AA section view of (a).

[0187] Figure 48 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 21 of the present invention.

[0188] Figure 49 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 22 of the present invention.

[0189] Figure 50 This is a front cross-sectional view of the servo-type acceleration sensor according to Embodiment 23 of the present invention.

[0190] Figure 51 This is a front cross-sectional view of a servo-type accelerometer that uses an optical sensor in this invention.

[0191] Figure 52 This is a model diagram of an existing active vibration damping table.

[0192] Figure 53This is a model diagram illustrating the basic structure and detection principle of an electrostatic capacitive accelerometer.

[0193] Figure 54 This is a front sectional view showing a specific structural example of an existing linear motion acceleration sensor.

[0194] Figure 55 In existing linear motion acceleration sensors Figure 55 (a) is a front view showing the shape of the front disc spring. Figure 55 (b) is from Figure 54 A front sectional view of the front panel 26, fixed side electrode 25, etc., was removed. Figure 55 (c) is Figure 55 Enlarged view of part A in (b).

[0195] Figure 56 This is a front cross-sectional view showing an example of an existing oscillating motion accelerometer.

[0196] Figure 57 It is a magnified diagram showing the oscillator of a swing motion accelerometer in swing motion.

[0197] Figure 58 This is a top view of the oscillator of a pendulum motion accelerometer. Figure 58 (a) is a diagram representing one face of the oscillator. Figure 58 (b) is a diagram representing the other side.

[0198] Explanation of reference numerals in the attached figures

[0199] 101 Permanent Magnets

[0200] 102 Movable side member

[0201] 105 Fixed Side Components

[0202] 116, 104 Movable Magnetic Yoke

[0203] 106 coil

[0204] 110 Movable part of displacement detector

[0205] 117. Gap Detailed Implementation

[0206] Here, returning to the origin, we focus on the actuator section of a servo-type accelerometer, which forms a closed-loop magnetic circuit with three elements: a permanent magnet, a coil, and a yoke. If the coil, one of these three elements, is fixed, the inherent problem of the moving / coil type (MC type) – namely, the difficulty of wiring processing, which is the main cause of reduced yield – is solved in one fell swoop. The present invention will now be described in two steps.

[0207] (I) Moving / Magnetic (MM) Accelerometer

[0208] (II) Moving / Yoke Type (MY Type) Accelerometer

[0209] First, let’s begin with (I) above.

[0210] (First Implementation)

[0211] This embodiment focuses on a moving / magnetic (MM) type where the permanent magnet moves and the coil is fixed, thus eliminating the need for extremely fine wire processing. Existing servo-type accelerometers are moving / coil (MC) type, where the coil moves linearly or oscillates in the axial direction. In contrast, in this embodiment, the coil is fixed while the permanent magnet moves axially. However, MM-type servo-type accelerometers are unprecedented. The reason for this is believed to be the inherent misconception that "MM-type sensors suffer from poor transmission characteristics / high-speed response in the high-frequency region due to the increased inertial mass of the moving part." This invention overcomes this "blind spot" through the following research: In this embodiment, by researching (i) a lightweight magnetic circuit structure for the moving part, (ii) a magnetic pole shape that reduces the influence of leakage flux, and (iii) coil specifications that balance increasing generating force and suppressing heat generation by increasing the coil housing volume, the weaknesses of the MM type are eliminated, and sensor performance surpasses that of the MC type. Hereinafter, the specific structure and structural features of this embodiment will be described in (1), and the effect of the present invention on the basic performance of the accelerometer will be verified by theoretical analysis in (2).

[0212] (1-1) Specific structure of this embodiment

[0213] Figure 1 This figure shows an example of a servo-type accelerometer sensor according to Embodiment 1 of the present invention. Figure 1 (a) is from Figure 1 In view (b), only the external appearance of the spiral disk, described later, is extracted from the AA direction view. Figure 1 (b) is a front sectional view of the sensor body.

[0214] 101 is a permanent magnet, 102 is the front pole piece, and 103 is a cylindrical gap formed to reduce the weight of the front pole piece (described later as the inertial mass adjustment part). 104 is the rear pole piece, 105 is the coil-side yoke, 106a is the force-applying coil, 106b is the calibration coil, and 107 is a protrusion formed on the inner surface of the coil-side yoke. 108 is the front spiral spring (hereinafter referred to as the front disc), and 109 is the rear spiral spring (hereinafter referred to as the rear disc). Figure 1 The front disk shown in (a) is formed by a peak portion 108a and a groove portion 108b, and the rear disk is also an elastic member of the same shape. That is, the movable side magnetic material member (movable side yoke) is composed of a front pole portion 102 and a rear pole portion 104. The fixed side magnetic material member is a coil side yoke 105. 110 is a movable side electrode, 111 is a fixed side electrode, 112a is a front panel, 112b is a rear panel, 113 is a central plate, and 114 is a fastening member made of non-conductive material that fastens the fixed side electrode and the front panel. The movable side electrode 110 and the fixed side electrode 111 constitute an electrostatic capacitance type displacement detection part. 115 is the inner peripheral surface of the coil side yoke 105, which is the coil mounting part of the two coils (106a, 106b), and 116 is the coil-facing surface of the front pole portion 102. In this embodiment, the force-applying coil 106a and the verification coil 106b are constructed in a frameless manner, and their outer peripheral surfaces are mounted on the convex coil mounting portion 115.

[0215] A radially oriented magnetic gap 117 (first gap) is formed between the coil-facing surface 116 and the coil mounting portion 115. An annular gap 118 (serving as a magnetic connection portion for the second gap) is provided between the protrusion 107 of the coil-side yoke and the rear pole piece 104, consisting of a narrow gap. A closed-loop magnetic circuit is formed by the sequence "permanent magnet 101 → front pole piece 102 → magnetic gap 117 → coil-side yoke 105 → annular gap 118 → rear pole piece 104", as shown by the dashed arrow. The annular gap 118, indicated by dashed circle B, is positioned with a sufficiently small magnetic reluctance compared to the magnetic gap 117. The annular gap 118 is a magnetic connection portion used to form a closed-loop magnetic circuit in a magnetic circuit using a permanent magnet. It is well known that when an electric current flows through a conductor placed in a magnetic field, a Lorentz force, which is an electromagnetic force, is generated. Regardless of the type of driving principle, the force relationship between the fixed side and the moving side is relative for all actuators. That is, if either the fixed side or the moving side is fixed, the other side will move. In this embodiment, if current flows through the force-applying coil 106a fixedly disposed in the space of the magnetic gap 117, a Lorentz force reaction force is generated that causes the movable part to move axially. The movable part in this embodiment is composed of a permanent magnet 101, a front pole piece 102, a rear pole piece 104, and a movable side electrode 110.

[0216] 119a and 119b are leads of the force-applying coil 106a, and 120a and 120b are leads of the verification coil 106b. These four leads pass through the coil-side magnetic yoke 105 and the front panel 112a, and are connected to an externally located control circuit. 121 is the inner circumferential side plate support ring, 121a is a cylindrical gap formed to reduce the weight of the inner circumferential side plate support ring, and 122 is the outer circumferential side plate support ring. The inner circumferential side plate support ring 121 and the outer circumferential side plate support ring 122 are made of non-conductive material (insulating material).

[0217] Electrical insulation is achieved between the front electrode portion 102, which is made of magnetic material, and the movable electrode 110 via the inner peripheral side plate support ring 121. Although eddy currents are generated on the surface of the electrode portion, this electrical insulation measure prevents the electrostatic capacitance signal between the two electrodes from being affected by these eddy currents. Furthermore, the outer peripheral side plate support ring 122 provides electrical insulation between the outer peripheral side of the front plate 108 and the coil-side yoke 105. Mica, ceramics, glass, etc., which are inorganic solid insulating materials, can be used as insulating materials. The inner peripheral side plate support ring 121 is bonded and fixed between the movable electrode 110, which is made of conductive material, and the front electrode portion 102. The inner peripheral side of the front plate 108 is clamped between the movable electrode 110 and the inner peripheral side plate support ring 121. Furthermore, the outer periphery of the front disc 108 is bonded and fixed to the outer periphery disc support ring 122. 123 is one of the two wires (leads) for detecting the electrostatic capacitance between the movable side electrode 110 and the fixed side electrode 111. The end of the wire 123 is connected to the disc spring 108 and is installed in a groove (not shown) formed in the outer periphery disc support ring 122. The front disc 108 serves as both a support for the movable part and a conductive path for detecting electrostatic capacitance. That is, in order to detect the minute electrostatic capacitance signal between the fixed side electrode 111 and the movable side electrode 110, complete electrical insulation is achieved between the movable side electrode 110 and the external conductive path (front disc 108, wire (lead) 123).

[0218] In this embodiment, the force-applying coil 106a and the verification coil 106 are arranged such that they surround the permanent magnet 101 from the outer periphery and are connected in series with the front pole piece 102 of the permanent magnet 101. Furthermore, an annular gap 118, having a sufficiently small magnetic reluctance compared to the magnetic gap 117, is arranged within the closed-loop magnetic circuit. The movable members that move axially are the permanent magnet 101, the front pole piece 102, the rear pole piece 104, the movable side electrode 110, and the inner peripheral side disk support ring 121. To achieve weight reduction, each movable member has a cavity on its inner periphery.

[0219] In this embodiment, the front and rear discs 108 and 109 use disc-shaped springs formed by a helical curve. This embodiment and the embodiments described later are similar, but the shape of the spring is not limited to this helical curve. As long as a spring structure and specifications that can obtain low stiffness and low resonant frequency are selected according to the characteristics required by the accelerometer, well-known cloud-shaped springs can also be used; for example, well-known cloud-shaped springs can also be used.

[0220] (1-2) Features of this embodiment

[0221] In this embodiment, the axial length of the front electrode portion 102 is set to L, and this axial length L is formed to be sufficiently long. Furthermore, a cylindrical gap portion 103 (inertial mass adjustment portion) with a thin radial thickness is provided inside the front electrode portion. This structure provides the following advantages, which are noteworthy.

[0222] (1) It can increase the force constant (electric / mechanical conversion efficiency) of the actuator.

[0223] (2) It can reduce the increase in the inertial mass of the movable part.

[0224] (3) Even if the number of coil turns is increased to increase the generating force, the heat generation can be suppressed.

[0225] use Figures 2-7 The effects of (1) above will be explained. Figure 2 This is a model diagram of the magnetic circuit of the MM-type accelerometer of the present invention. Figure 3 This is a model diagram of the magnetic circuit of an existing MC-type accelerometer. Figure 2 The reference numerals for each element in the figure correspond to Figure 1 The reference numerals for the elements in (b). Similarly, Figure 3 The reference numerals for each element in the figure correspond to Figure 54 The reference numerals for each element in the accompanying drawings. And, as... Figure 3 As shown, in the conventional MC type, there is only one gap 29 forming a closed-loop magnetic circuit. In the case of the MM type of the present invention, as Figure 2 As shown, two gaps (117, 118) are required to form a closed-loop magnetic circuit. By providing a secondary gap (second gap) as a magnetic connection relative to the main gap (first gap) separating the coil, the coil can be fixedly positioned in a magnetic field with high magnetic flux density, enabling the coil to generate a large Lorentz force. Furthermore, the gap of the first gap is set to δ1, and the gap of the second gap is set to δ2, where δ1 > δ2. By making the magnetic reluctance of the magnetic connection sufficiently smaller than that of the first gap, the influence of the magnetic connection on the generated force can be reduced.

[0226] The following analysis results of the permanent magnet magnetic circuit are presented using the above analysis model. Figure 4 This is a graph showing the analysis results of the relationship between the generated force F and the length L of the electrode portion. Figure 5 This is a graph showing the analytical results representing the relationship between the leakage coefficient σ and the electrode length L.

[0227] exist Figure 4 In the example, characteristic curve (1) uses a samarium cobalt magnet, and the total coil length is the basic specification (l = l0) described in Table 1 below. Characteristic curve (2) uses a samarium cobalt magnet, and the total coil length is l = l0 × 1.6. Characteristic curve (3) represents the sensor in this embodiment. Figure 1 This refers to the case where neodymium magnets are used, and the total coil length is l = l0 × 1.6. Point A in the same diagram represents the pole piece length L = L in the existing MC type. A =0.3cm, generating force F =0.0064N. Point B in the same figure represents the length L = L of the electrode portion of the MM type of this invention. B =0.6cm, generating force F =0.018N. Therefore, compared with the existing MC type, the MM type of the present invention generates 2.8 times more force.

[0228] exist Figure 5 In the curve representing the leakage coefficient relative to the electrode length L, the leakage coefficient σ represents the ratio of "magnetic flux that contributes to force generation" to "total magnetic flux." The closer σ is to 1, the greater the force generated. According to... Figure 5 By increasing the axial length L of the pole piece, the ratio of the effective magnetic flux (gap permeability) to the leakage flux (leakage permeability) passing perpendicularly through the magnetic gap 117 can be reduced. The gap permeability is a magnetic flux that contributes to force generation, while the leakage permeability does not. That is, according to the structure of this embodiment, the force generated relative to the same current (electromechanical conversion efficiency) can be increased.

[0229] exist Figure 4 In the diagram, the characteristic curve (1) is divided into curves α and β with significantly different slopes, and the intersection of the envelopes of each curve is set as C. In the case of 0 < L < L... A Within this range, the generated force F increases significantly with the increase of the electrode length L. When L > L... A Within this range, the increase in force F is minimal. Therefore, the electrode length of most existing MC-type sensors is set to L = L. A (exist Figure 2 In the case of L A =0.3cm). The reason is that, in the case of an MC-type sensor, if the number of coil turns is increased, thus increasing the length L, the inertial mass also increases, and therefore the required force also increases. That is, this is because it cancels out the effect of increasing the length L.

[0230] The above (2) concerns that if the electrode portion is made into a thin cylindrical shape, the mass will not increase significantly even if the electrode portion is lengthened. Figure 6 This is a graph representing the inertial mass m of the movable part relative to the length L of the electrode portion. The front electrode portion has an outer shape ΦD. P It is composed of a cylindrical shape with a thickness t in the radial direction. Here, it is assumed to be ΦD. P =10mm, t=1mm. In Figure 6 In the middle, at the length L of the electrode portion A When the radius is 3mm, the total inertial mass of the movable part is m = 4.48g. At L... A When the diameter is 6mm, m = 5.16g. Therefore, when the electrode length is doubled, the increase in total inertial mass is 15%. Furthermore, consider the case where the electrode has the same outer diameter and a thickness t = 0.5mm. In this case, when the electrode length is doubled, the increase in total inertial mass is 8.4%.

[0231] The feature of (3) above is that it utilizes the insights of (2) above. Figure 7 This represents the coil storage volume V. C The diagram shows the length L relative to the pole piece. In this embodiment, the radial gap of the magnetic gap 117 is 2.5 mm, the radial thickness of the coil housed in the magnetic gap 117 is 2 mm, and the radial gap between the coil-facing surface 116 and the coil is 0.5 mm. By changing the pole piece length from L = 3 mm to L = 6 mm under the above conditions, the coil housing volume V... C The mass increases to 2.7 times. However, as mentioned above, the inertial mass of the movable part increases by only 15% when the thickness of the electrode portion is t = 1 mm, and by only 8.4% when the thickness is t = 0.5 mm.

[0232] If the coil's storage volume can be increased, then even if the number of coil turns increases and the generated force increases, the heat generation that causes thermal noise can be suppressed. The coil's resistance is proportional to its total length and inversely proportional to its cross-sectional area. Therefore, if the total coil length is set to n times the coil's cross-sectional area, and the coil's shape is set to √n times the coil's length, the resistance will not increase. In this case, the coil storage area can be √n×n.

[0233] (2) Comparison of the specifications of the present invention with those of existing sensors

[0234] In this section, based on a comparison with existing MC-type sensors, we use theoretical analysis to verify the effect of the structural features (1) to (3) described in section (1) on the basic performance of the accelerometer.

[0235] (2-1) Specifications of the linear motion type MC accelerometer and the sensor of this invention

[0236] Here, through theoretical analysis, the basic performance of the linear motion type moving / magnetic sensor (hereinafter referred to as linear motion type MM type) and the existing linear motion type moving / coil type (hereinafter referred to as linear motion type MC type) used as sensors of the present invention are evaluated. Table 1 compares the specifications of the existing linear motion type MC type and the sensor of the present invention (MM type).

[0237] (1) Specifications of inertial mass m: The inertial mass m is 1.25g in the MC form and 5g in the MM form. The inertial mass m = 1.25g in the MC form... Figure 54 In the process, the movable side electrode 24, the force application coil 16a, the verification coil 16b, the coil frame 17, and the coil frame support members 18 and 19 are determined. The inertial mass m = 5g of the MM type is the sum of the masses of the movable side electrode 110, the inner peripheral side disk support ring 121, the front pole piece 102, the permanent magnet 101, and the rear pole piece 104. As described above, the value of the inertial mass m = 5g is set based on the following conditions: (i) improving the sensor sensitivity in the low frequency region, and (ii) the wide frequency characteristics required by the active vibration damping table. (The mass m of the permanent magnet is used as a reference for the inertial mass m.) p Based on the definition of the mass m of the movable part

[0238] (2) Specifications of Coil Length and Coil Resistance Ra: The total coil length of the MM type is set to n = 1.6 times that of the MC type. As mentioned above, in order to make the coil resistance Ra the same, the cross-sectional area of ​​the MM type coil is set to n times, and the coil wire diameter is set to √n = 1.26 times. Therefore, the coil storage space Sn = n × √n = 2.0 times. According to this structure, if the same current I flows through two sensors, the MM type will generate less heat (W = I) compared to the MC type. 2 If (×Ra) remains the same, the above (ii) can be satisfied. And the force generated by the actuator can be more than n times.

[0239] (3) Specifications of electrical gain: Set the position sensor sensitivity to Ks, the adjustment gain to Kc, and the proportional gain to Kp. The overall electrical gain Kpt = Ks × Kc × Kp. This Kpt is set to be the same in both MM and MC modes.

[0240] [Table 1]

[0241] Comparison of accelerometer specifications

[0242]

[0243] (2-2) Theoretical Analysis Results

[0244] Figure 8This is a control block diagram of an accelerometer used for theoretical analysis. Equations (1) to (3) representing the detection principle of the above-mentioned electrostatic capacitive accelerometer are replaced with a control block diagram.

[0245] (i) Comparison of gain / phase characteristics

[0246] Figure 9 In the specifications in Table 1, the gain / phase characteristics of the following three cases (1) to (3) are compared: (1) the existing MC type, (2) the MM type of the present invention, and (3) the case where only the inertial mass m is 4 times in the existing MC type specifications in Table 1. Hereinafter, the performance of the above three cases is evaluated by the gain characteristics under the premise of being mounted on an active vibration damping table. The gain characteristics of (1) and (2) are not significantly changed. In the MM type of the present invention in (2), the resonant frequency f0 = 380 Hz. In the case of (3), the resonant frequency f0 = 380 → 220 Hz, and the bandwidth is reduced. The phase characteristics are evaluated by the phase delay near f = 100 Hz (dashed circle A). As will be described later in Supplement (2), the phase characteristics near f = 100 Hz are an important performance evaluation index when applying an accelerometer to an active vibration damping table. It is preferable to minimize the phase delay near f = 100 Hz as much as possible. The higher the resonant frequency f0, the more the phase delay near f = 100 Hz can be reduced. The phase characteristics of (1) and (3) are approximately the same at f = 100 Hz. However, at f > 100 Hz, a significant phase delay occurs in the case of (3) above. In the MM formula of the present invention in (2) above, the phase delay is significantly improved compared to (1) and (3).

[0247] (ii) Comparison of actuator-generated forces

[0248] Figure 10 In the specifications in Table 1, the generating force of the actuators relative to time was compared between (1) the existing MC type and (2) the MM type of the present invention. It is assumed that the input acceleration is an amplitude of 1.0 × 10⁻⁶. -6 m / s 2 A sine wave of (0.1 mGal). Compared with the existing MC type, the MM type of this invention generates a force that is 4 times greater in proportion to the inertial mass. The increased force accompanying the increased inertial mass can compensate for the weakness of the electrostatic capacitive type, which has reduced sensitivity in the low-frequency region.

[0249] (iii) Comparison of the impact of mechanical noise

[0250] Figure 11 In the specifications in Table 1, the impact of mechanical noise on the sensor output is compared between (1) the existing MC type and (2) the MM type of the present invention. Here, it is assumed that mechanical noise is an interference factor that hinders the smooth movement of the movable part. Assume an amplitude of 1.0 × 10⁻⁶.-6 A sinusoidal external force N (mechanical noise) is applied to the output shaft of the actuator (refer to...). Figure 8 (Control block diagram). In this invention, it is known that the impact of mechanical noise applied to the actuator on the sensor output is reduced to 1 / 4 compared to the existing type. This effect is due to the increased force generated by the actuator caused by the increase in inertial mass. That is, compared with the MC type, the disadvantage of the increased inertial mass of the movable part is that it becomes an advantage relative to the mechanical noise.

[0251] (iv) Comparison of coil currents

[0252] Figure 12 In the specifications in Table 1, the coil current was compared for the following three cases (1) to (3): (1) the existing MC type, (2) the MM type of the present invention, and (3) the case where only the inertial mass m is 4 times in the existing MC type specifications in Table 1. Assume the input acceleration is an amplitude of 1.0 × 10⁻⁶. -6 m / s 2 A sine wave of (0.1 mGal). Compared to the existing MC type, the increase in coil current in the MM type of the present invention is minimal. However, when the inertial mass m of the existing MC type is set to 4 times, the coil current increases proportionally to the inertial mass. This is because, in the present invention, while the total length (number of turns) of the coil is increased by 1.6 times, the coil wire diameter is increased by 1.26 times. The reason for this structure is that, as described above, by providing a sufficiently long cylindrical gap 103 (an inertial mass adjustment portion of length L) on the front pole portion 102, a large coil storage space can be formed. In this embodiment, the gap 103 uses a perfectly circular cylindrical shape, but since the purpose is to reduce the inertial mass, the gap may not be perfectly circular. For example, it may be a polygonal shape, or a shape with different inner diameters in the axial direction. These shapes are included and referred to as approximately cylindrical shapes.

[0253] By summarizing the features of the MM-type embodiments of the present invention shown in (i) to (iv) above, the difficulty of handling extremely fine lines, which is an inherent weakness of the MC type, can be fundamentally solved, and the following effects can be obtained.

[0254] (1) Compared with the existing MC type, the MM type of the present invention can achieve high-frequency characteristics that are no less than those of the MC type. That is, the weaknesses of the MM type are eliminated.

[0255] (2) The impact of mechanical noise on the sensor output can be reduced to 1 / 4 compared to the existing MC type. In addition, the increased force due to the increased inertial mass can compensate for the weakness of the electrostatic capacitive type, which has reduced sensitivity in the low-frequency region.

[0256] (3) Compared with the existing MC type, the increase in coil current and the amount of heat generated that causes thermal noise is minimal.

[0257] (2-3) Regarding the setting range of the mass m of the movable part

[0258] The range within which the mass *m* of the movable part of the MM-type sensor of the present invention can be set is examined. First, the lower limit of the settable mass *m* of the movable part is examined. If, due to weight reduction, the mass *m* of the movable part is infinitely close to that of the MC-type sensor, then the transmission characteristics of the MM-type sensor are the same as those of the MC-type sensor. In this case, since the mass *m* of the movable part cannot be less than the mass *m* of the permanent magnet... p Therefore, the mass m p The value of becomes the basis for determining its limit. In this embodiment ( Figure 1 In (b)), pole pieces (102, 104) for forming a magnetic circuit are essential in the movable part including the permanent magnet 101. In this embodiment, m p =1.52g, the mass of the front electrode portion 102 is m1 = 1.36g, the mass of the rear electrode portion 104 is m2 = 0.63g, and including the movable side electrode 111 and the inner peripheral side disk support ring 353, the mass is m3 = 1.45g. Therefore, the total mass of the movable part is m = m p +m1+m2+m3=4.96≈5.0g. Here, to achieve weight reduction, by making the plate thickness of components m1 and m2 t=1.0→0.5mm, m1+m2→1.0g. If the movable side electrode is aluminum and the plate thickness of each component is t=1.0→0.5mm, then m3→0.5g. Furthermore, considering the magnetic reluctance of the magnetic circuit and the component precision during machining, a plate thickness t=0.5mm is the limit. As a result, the total mass of the movable part m=m p +m1+m2+m3=2.5g. Therefore, the lower limit value m of the movable part mass of the MM-type sensor of the present invention is... min If the mass of the permanent magnet is m p Based on this, then m min =2m p Therefore, the range of movable part masses for which this invention can be used as an acceleration sensor is m ≥ 2m. p .

[0259] Next, we examine the upper limit of the movable part's mass m that can be set. The upper limit of the movable part's mass m is closely related to the bandwidth (resonant frequency f0) of the accelerometer.

[0260] [Mathematical Expression 5]

[0261]

[0262] in,

[0263] [Mathematical Expression 6]

[0264]

[0265] In equation (6), as shown in Table 1, K PT It is the position sensor sensitivity K. S Adjusting the gain K C , proportional gain K P The accumulation of K. t R is the force constant of the actuator. a It is the resistance of the coil. According to equation (5), the upper limit of the mass of the movable part is m. max It is determined by the resonant frequency f0 (bandwidth) required by the sensor.

[0266] [Mathematical Expression 7]

[0267]

[0268] Therefore, the range of the movable part mass for which the present invention can be used as an acceleration sensor is m ≤ m max As described above, when applying the sensor of the present invention to an active vibration damping station, the phase characteristics around f = 100 Hz are an important performance evaluation indicator. It is preferable to minimize the phase delay around f = 100 Hz as much as possible; for this purpose, the resonant frequency f0 needs to be set relatively high. In practice, sufficient performance can be obtained if f0 > 250 Hz.

[0269] (Second Implementation)

[0270] Figure 13 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 2 of the present invention. One feature of the MM-type accelerometer of the present invention is that, as described above, it eliminates the need for the complex ultra-fine wire processing inherent in the MC-type, resulting in a significant cost reduction in the manufacturing process. However, compared to the MC-type, the MM-type is generally considered to have reduced high-frequency characteristics due to the increased inertial mass of the movable part. However, the fundamental concept proposed in this invention is to overcome the aforementioned weaknesses of the MM-type by studying the magnetic circuit and the shape of the components constituting the magnetic circuit.

[0271] This embodiment further implements the basic concept of the present invention. That is, by selecting the component shape and magnetic material, although it is an MM type, the inertial mass m of the movable part is made close to the MC type. 351 is the front pole piece, 352 is the rear pole piece, and 353 is the inner peripheral side disc support ring. 354 is an axially magnetized ring-shaped permanent magnet, and 355 is a cylindrical void formed inside the front pole piece. The front pole piece 351 is the main component constituting the magnetic circuit and accounts for a large proportion of the mass of the movable part. In this embodiment, the front pole piece is made of a soft magnetic material and can be manufactured by stamping. Permalloy is a material with low coercivity and high permeability. Therefore, even if the thickness t of the cylindrical front pole piece is thin enough, it can be unaffected by magnetic reluctance and the length L can be long enough. As described above, the longer the length L of the front pole piece, the more the influence of magnetic flux leakage on the generated force can be reduced, and therefore the generated force can be increased even under the same current. Meanwhile, to increase the coil storage volume, coil specifications (number of turns, wire diameter) that can suppress coil heating can be selected. In this embodiment, even if the thickness t < 0.5 mm, a magnetic circuit that does not affect the actuator's generating force can be constructed. Furthermore, in this embodiment, to achieve weight reduction, the permanent magnet 354, the rear pole piece 352, and the inner peripheral side plate support ring 353 can also be hollow.

[0272] (Third Implementation)

[0273] In the first embodiment, as described above, the present invention focuses on the following aspects.

[0274] In other words, the key point is that "the weakness of the MM type, which has increased inertial mass of the moving part, actually becomes an advantage in improving the sensitivity of sensors in the low-frequency region." In particular, the low sensitivity of capacitive sensors in the low-frequency region can compensate for this weakness. Figure 14 This is a front cross-sectional view of the servo-type accelerometer according to Embodiment 3 of the present invention, which fully and flexibly utilizes the advantages of the MM type. That is, in contrast to the second embodiment described above, the inertial mass of the movable part is set to be large, thereby significantly improving the sensor sensitivity in the low-frequency region. However, as a trade-off, the high-frequency band is limited. 381 is the front pole piece, 382 is the rear pole piece, and 383 is the inner peripheral side disk support member. The front pole piece 381 and the rear pole piece 382 are movable side magnetic yokes. No hollow parts are formed in any component constituting the movable part. The effect of making the front pole piece 381, which accounts for a large proportion of the mass of the movable part, a solid member is significant.

[0275] When the sensor of this embodiment is applied, for example, to an active vibration damping table, a control system that focuses on improving the vibration damping characteristics in the low-frequency region can be designed. Furthermore, by combining the two sensors (1) that thoroughly reduce the inertial mass of the movable part (second embodiment) and (2) that sufficiently increase the inertial mass of the movable part (this embodiment), an active vibration damping / anti-vibration system (not shown) that can cover from low to high frequencies can be realized.

[0276] (Fourth Implementation)

[0277] Figure 15 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 4 of the present invention. In the above embodiment, an annular gap formed by a narrow gap (e.g., Figure 1 (b) The dashed circle B) forms a closed-loop magnetic circuit. In this embodiment, instead of the annular gap, the spiral / disc spring itself is used as the component forming the magnetic circuit.

[0278] 401 is the rear plate (second transmission part), 402 is the front plate made of conductive material, 403 is a permanent magnet, and 404 is a positioning pin installed at the center of the permanent magnet. 405 is the front pole piece, 406 is the outer peripheral plate support ring, 407 is the inner peripheral plate support member, 408 is the coil-side magnetic yoke, and 409 is the magnetic gap part (first transmission part). A closed-loop magnetic circuit is formed as shown by the dashed arrow: "Permanent magnet 403 → Front pole piece 405 → Coil-side magnetic yoke 408 → Rear plate 401 → Permanent magnet 403". This embodiment is not limited to this one; other embodiments are similar. However, the plates 401 and 402, which serve as elastic support members, may not be helical in shape; for example, they may be known cloud-shaped springs.

[0279] The rear disk 401 and the front disk 402 may not be of the same shape or material. To achieve electrical insulation between its inner circumference and the front electrode portion 405, the front disk 402 is fitted with an inner circumferential disk support member 407 made of a non-conductive material. The front disk 402 is preferably made of a non-magnetic material. Furthermore, to achieve electrical insulation between its outer circumference and the coil-side yoke 408, an outer circumferential disk support ring 406 made of a non-conductive material is fitted. However, electrical insulation of the rear disk 401 is not required. With this embodiment, which eliminates the need for a magnetic connection, a servo-type accelerometer can be implemented with a simple structure.

[0280] (Fifth Implementation)

[0281] Figure 16This is a front cross-sectional view of the servo-type accelerometer according to Embodiment 5 of the present invention. A permanent magnet is disposed in the cylindrical gap of the front pole piece, thereby achieving a compact sensor body. 251 is the axially magnetized permanent magnet, 252 is the front pole piece, and 253 is the space formed between the outer surface of the permanent magnet and the inner surface of the front pole piece. 254 is the rear pole piece, 255 is the coil-side yoke, 255a is a protrusion formed on the inner surface of the coil-side yoke, 256 is the force-applying coil, and 257 is the calibration coil. 258 is the front plate, 259 is the rear plate, 260 is the movable side electrode, 261 is the fixed side electrode, 262a is the front panel, 262b is the rear panel, 263 is the central plate, 264 is the fastening member, 265 is the coil mounting portion in the inner circumferential surface of the coil-side magnetic yoke, 266 is the coil-facing surface in the front pole piece 252, and a radial magnetic gap 267 is formed between the coil-facing surface 266 and the coil mounting portion 265.

[0282] The aspect in which an annular gap 268, consisting of a narrow gap, is provided between the protrusion 255a of the coil-side yoke and the rear pole piece 254 is the same as in the above embodiment. 269 is an outer peripheral support ring, and 270 is an inner peripheral support ring.

[0283] The permanent magnet is housed inside a cylindrical cavity 253, with one end face fixed to the front end face 271 of the front pole piece. Furthermore, the other end face of the permanent magnet is fixed to the rear pole piece.

[0284] A closed-loop magnetic circuit is formed by "permanent magnet 251 → front pole piece 252 → magnetic gap 267 → coil side yoke 255 → protrusion 255a → annular gap 268 → rear pole piece 254 → permanent magnet 251", as shown by the dashed arrow.

[0285] (Sixth Implementation Method)

[0286] Figure 17 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 6 of the present invention. A coil frame made of a material with good thermal conductivity is used to improve heat dissipation, and a magnetic circuit shape is formed to reduce leakage flux. That is, both the reduction of sensor noise related to thermal noise and the improvement of actuator generating force are achieved.

[0287] 201 is a permanent magnet magnetized in the axial direction; 202 is a front pole piece; 203 is a cylindrical gap formed inside the front pole piece; 204 is a rear pole piece; 205 is a coil-side yoke; 206a is a force-applying coil; and 206b is a calibration coil. 207 is a protrusion formed on the inner surface of the coil-side yoke; 208 is a front disc; 209 is a rear disc; 210 is a movable side electrode; 211 is a fixed side electrode; 212a is a front panel; 212b is a rear panel; 213 is a central plate; 214 is a fastening member; 215 is a coil mounting portion in the inner circumferential surface of the coil-side yoke; and 216 is a coil-facing surface in the front pole piece 202. A radially oriented magnetic gap 217 is formed between the coil-facing surface 216 and the coil mounting portion 215. The aspect in which an annular gap 218, consisting of a narrow gap, is provided between the protrusion 207 of the coil-side yoke and the rear pole piece 204 is the same as in the above embodiment. 219 is an outer peripheral support ring, and 220 is an inner peripheral support member.

[0288] 221 is the coil frame, and 223 is the recess formed between the outer periphery of the coil frame and the coil-side magnetic yoke 201. In the embodiment, the coil frame 221 is made of non-magnetic aluminum with good thermal conductivity.

[0289] Figure 18 The diagram illustrates the flow of magnetic flux in this embodiment, indicated by arrows (dashed lines). The image of "sand" represents the non-magnetic components constituting the accelerometer. Furthermore, components using magnetic materials are indicated by the usual "slashes." Specifically, the front panel 212a, rear panel 212b, coil frame 221, force coil 206a, calibration coil 206b, outer peripheral support ring 220, inner peripheral support member 220, front disk 208, rear disk 209, and movable side electrode 210 are all composed of non-magnetic components. A closed-loop magnetic circuit is formed as shown by the dashed arrows: "Permanent magnet 201 → front pole piece 202 → magnetic gap 217 → coil side yoke 205 → protrusion 207 → annular gap 218 → rear pole piece 204 → permanent magnet 201."

[0290] The magnetic flux A flowing vertically in the gap 217 effectively contributes to the force generation of this actuator. The magnetic fluxes B1 and B2 flowing from the corner of the coil-opposite surface 216 to the corner of the inner circumferential surface 205 of the coil-side yoke are leakage fluxes and do not contribute to force generation. The ease of flux flow in the magnetic circuit is represented by the permeability, which is the reciprocal of the magnetic reluctance. That is, let the gap permeability of the magnetic path through which flux A flows be P. g Let the leakage permeability of the magnetic paths through which leakage fluxes B1 and B2 flow be P, respectively. f1 P f2 If P g 》P f1 or Pg 》P f2 This allows for the generation of a large force. The recess 223 formed on the coil-side yoke reduces the leakage flux B2 and decreases the leakage permeability P. f2 It makes a significant contribution. The recess 223 is formed on the inner surface of the coil-side yoke near the axial end face of the coil, such that the radial distance between the movable part and the fixed member is longer than that between the two ends. The reduction effect of leakage flux generated by the recess 223 is not limited to this embodiment. Furthermore, since all the components around the leakage flux B1 flow are made of non-magnetic material, the leakage conductance P can be sufficiently reduced. f1 .

[0291] Figure 19 The diagram, illustrated by arrows (dashed lines), shows the heat flow in this embodiment. The outer peripheral surface of the coil frame 221 is in close contact with the inner peripheral surface 215 of the coil-side yoke. Extending to cover the recess 223, it is also in close contact with the side surface and inner peripheral surface 215a of the protrusion 207. Therefore, as shown by the arrows in the diagram, the heat generated by the coil can be easily dissipated through the aluminum frame 221 → coil-side yoke 205 to the front panel 212a and rear panel 212b.

[0292] exist Figure 54 In the case of the existing linear motion accelerometer (MC type) shown, the coil frame 17 and coils 16a and 16b are arranged in a state of suspension in the air. The coil frame support members 18 and 19 supporting the coil frame 17 are made of non-magnetic and non-conductive material. In addition, the disc springs 20 and 21 are thin plate members, so heat dissipation based on thermal conduction of the coil cannot be expected.

[0293] exist Figure 56 The same applies to the existing oscillating motion type / coil type (MC type) shown. In the heat conduction path connecting the torque coil 597 and the fixing part (yoke 591, 592), quartz glass (a non-magnetic and non-conductive material) with low thermal conductivity is sandwiched, so heat dissipation of the coil cannot be expected. That is, in the sensor of this embodiment, the reason for obtaining sufficient heat dissipation effect of the coil compared to the existing method is due to the utilization of the MM type feature that allows the coil to be fixed / adhered to the wall surface.

[0294] (Seventh Implementation)

[0295] Figure 20 (a) is a front sectional view of the servo-type accelerometer sensor according to Embodiment 7 of the present invention. Figure 20 (b) is Figure 20(a) is a cross-sectional view AA. All the above embodiments use sensor structures with permanent magnets magnetized in the axial direction. In this embodiment, a magnetic circuit is constructed using multiple permanent magnets, referred to as segmented magnets, magnetized in the radial direction.

[0296] 451 is a permanent magnet, and 452 is the front pole piece. The permanent magnet is composed of segmented permanent magnets 451a, 451b, 451c, and 451d magnetized in the radial direction, and is mounted on the front pole piece 452. 453 is a cylindrical gap formed to reduce the weight of the front pole piece. 454 is the rear pole piece, 455 is the coil-side yoke, and 456 is the force-applying coil or a coil part composed of a force-applying coil and a verification coil. 457 is a protrusion formed on the inner surface of the coil-side yoke; 458 is a front disc; 459 is a rear disc; 460 is a movable side electrode; 461 is a fixed side electrode; 462a is a front panel; 462b is a rear panel; 463 is a central plate; 464 is a fastening member; 465 is a coil mounting portion in the inner circumferential surface of the coil-side yoke; and 466 is the outer circumferential surface of the permanent magnet, corresponding to the coil-facing surface. A radially oriented magnetic gap 467 is formed between the coil-facing surface 466 and the coil mounting portion 465. The aspect where an annular gap 468, consisting of a narrow gap, is provided between the protrusion 457 of the coil-side yoke and the rear pole piece 454 is the same as in the above embodiment. 469 is an outer circumferential support ring; and 470 is an inner circumferential support ring. A closed-loop magnetic circuit is formed by "permanent magnet 451 → magnetic gap 467 → coil side yoke 455 → protrusion 457 → annular gap 468 → rear pole piece 454 → front pole piece 452 → permanent magnet 451", as shown by the dashed arrow.

[0297] (Eighth Implementation Method)

[0298] Figure 21 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 8 of the present invention. In the above embodiment, an annular gap formed by a narrow gap (e.g.) is provided. Figure 1 (b) The dashed circle B) forms a closed-loop magnetic circuit. In this embodiment, instead of the annular gap, a magnetic connection for forming a closed-loop magnetic circuit is constructed by a combination of a segmented permanent magnet magnetized in the radial direction and a fixed-side coil.

[0299] 651 is a segmented permanent magnet (auxiliary magnet), and 652 is the rear pole piece. The segmented permanent magnet, like in the seventh embodiment, consists of multiple segmented permanent magnets magnetized in the radial direction (see reference). Figure 20The sensor body is constructed as described in (b) and mounted on the rear electrode portion 652. 653 is a cylindrical gap formed to reduce the weight of the rear electrode portion. 654 is the front electrode portion, 655 is a permanent magnet magnetized in the axial direction, 656 is the front end face of the front electrode, and 657 is a cylindrical gap formed inside the front electrode. The permanent magnet 655 is housed inside the cylindrical gap 657, and one end face is fixed to the front end face 656 of the front electrode. Furthermore, the other end face of the permanent magnet is fixed to the rear electrode. Similar to the fifth embodiment, this embodiment utilizes the cylindrical gap 657 of the front electrode portion 654, in which the permanent magnet 655 is disposed, thereby achieving a compact sensor body.

[0300] 658 is the coil-side magnetic yoke, 659 is the front force-applying coil, 660 is the rear force-applying coil (auxiliary coil), and 661 is the calibration coil section.

[0301] 662 is the front plate, 663 is the rear plate, 664 is the movable side electrode, 665 is the fixed side electrode, 666a is the front panel, 666b is the rear panel, 667 is the central plate, 668 is the fastening member, 669 is the coil mounting portion in the inner circumferential surface of the coil-side yoke, 670 is the coil-facing surface (outer circumferential surface of the front pole piece), 671 is the magnetic gap, 672 is the outer circumferential support ring, and 673 is the inner circumferential support ring. A closed-loop magnetic circuit is formed by "permanent magnet 655 → front pole piece 654 → magnetic gap 671 → coil-side yoke 658 → permanent magnet 651 → rear pole piece 652 → permanent magnet 655", as shown by the dashed arrow.

[0302] In this embodiment, since the magnetic connection portion is composed of a radially magnetized magnet and a fixed coil, both the front and rear sides function as voice coil motors, thus increasing the generated force. Furthermore, similar to the first embodiment, the radial gap of the magnetic gap 671 is approximately 2.5 mm, and the radial gap between the coil-facing surface 670 and the coil is approximately 0.5 mm. Therefore, compared to the case where a narrow gap forms an annular gap (e.g., the annular gap 118 in the first embodiment), assembly during mass production is also easier.

[0303] (Ninth Implementation)

[0304] Figure 22 (a) is a front sectional view of the servo-type accelerometer sensor according to Embodiment 9 of the present invention. Figure 22 (b) and Figure 22 (c) is a cross-sectional view showing the segmented permanent magnet magnetized in the radial direction using this embodiment.

[0305] In this embodiment, the front permanent magnet is composed of segmented magnets magnetized radially, and the magnetic connection part is also composed of segmented magnets magnetized radially and a fixed coil. Both the front and rear sides function as voice coil motors, thus increasing the generated force. 701 is the front permanent magnet, 702 is the rear permanent magnet, and 703 is the pole piece (movable magnetic yoke). Both the front and rear permanent magnets are composed of multiple segmented permanent magnets magnetized radially and are mounted on the pole piece 703. Figure 22 (b) and Figure 22 As shown in (c), the magnetization directions in the radial direction of each permanent magnet are opposite.

[0306] 704 is the gap of the electrode portion; 705 is the front plate; 706 is the rear plate; 707 is the movable side electrode; 708 is the fixed side electrode; 709a is the front panel; 709b is the rear panel; 710 is the central plate; 711 is the fastening member; 712 is the coil-side yoke; 713 is the coil frame; 714 is the front coil; 715 is the rear coil. 716 is the outer peripheral support ring; 717 is the inner peripheral support ring; 718 is the front end face of the electrode portion; 719 is the rear end face of the electrode portion; 720 is the support ring for the rear plate spring; 721 is the coil mounting portion, which serves as the inner peripheral surface of the coil-side yoke 712. 722a and 722b are magnetic gaps formed between the coil mounting portion and the two permanent magnets on the front and rear sides, respectively. A closed-loop magnetic circuit is formed as shown by the dashed arrow: "Permanent magnet 701 → Coil-side yoke 712 → Permanent magnet 702 → Pole portion 703 → Permanent magnet 713". In this embodiment, the space formed by the rear permanent magnet and the rear coil is a magnetic connection portion. In this embodiment, both the front and rear sides function as voice coil motors, thus increasing the generated force. Furthermore, the radial gap between the magnetic gap portions 722a and 722b is approximately 2.5 mm, and the radial gap between the outer peripheral surfaces of the two permanent magnets and the coil frame is approximately 0.5 mm. Therefore, compared to the case where a narrow gap forms an annular void portion (e.g., the annular void portion 118 in the first embodiment), assembly during mass production is also easier.

[0307] (Tenth Implementation)

[0308] Figure 23 This is a front cross-sectional view of the differential servo-type accelerometer sensor according to Embodiment 10 of the present invention. Specifically, focusing on the structural features of a linear motion MM-type sensor where both left and right output shafts are open, a differential capacitive sensor is constructed by providing electrodes for detecting electrostatic capacitance at both the left and right locations. By using a differential accelerometer, a high-resolution sensor can be achieved, whose output is less susceptible to interference signals such as noise and drift.

[0309] (i) Structural Description

[0310] 301 is a permanent magnet, 302 is the front pole piece, and 303 is a cylindrical gap (inertial mass adjustment part). 304 is the rear pole piece, 305 is the coil-side yoke, 306a is the force-applying coil, 306b is the calibration coil, and 307 is a protrusion formed on the inner surface of the coil-side yoke. 308 is the front disk, and 309 is the rear disk. 310a is the front movable electrode, 311a is the front fixed electrode, 310b is the rear movable electrode, and 311b is the rear fixed electrode.

[0311] 312a is the front panel, 312b is the rear panel, 313a is the front center plate, 313b is the rear center plate, 314a is the front fastening member, and 314b is the rear fastening member. 315 is the inner circumferential surface of the coil-side yoke 305, 316 is the coil-facing surface of the front pole piece, and 317 is a radially spaced magnetic gap formed between the coil-facing surface 316 and the coil mounting portion 315. An annular gap 318, consisting of a narrow gap, is provided between the protrusion 307 of the coil-side yoke and the rear pole piece 304.

[0312] Furthermore, the annular gap 318 has a narrow gap with sufficiently low magnetic resistance compared to the magnetic gap 317. Similar to Embodiment 1, a closed-loop magnetic circuit is formed via "permanent magnet 301 → front pole piece 302 → magnetic gap 317 → coil-side yoke 305 → annular gap 318 → rear pole piece 304". The leads of the force coil 306a and the verification coil 306b pass through the coil-side yoke 305 and the front panel 312a, and their connection to the externally located control circuit is the same as in Embodiment 1 (not shown). 319a is the inner circumferential support ring of the front disk, 319b is the inner circumferential support ring of the rear disk, 320a is the outer circumferential support ring of the front disk, and 320b is the outer circumferential support ring of the rear disk. All four rings are made of a non-conductive material.

[0313] The fastening methods for the front plate 308 and the rear plate 309 are the same as in Embodiment 1. Furthermore, the method for connecting the wires that detect the electrostatic capacitance between the movable electrode and the fixed electrode to the external environment is also the same as in Embodiment 1 (not shown).

[0314] Figure 24This diagram illustrates that the differential servo-type accelerometer of this embodiment can be composed of three units. 330 is the front unit, 331 is the drive unit, and 332 is the rear unit. Each unit is an independent unit, and individual components can be installed. Once the components of each unit are installed, the three units are combined into one unit, as shown by the arrows in the diagram. After being combined, only the gap between the movable electrode and the fixed electrode on the front side and the gap between the movable electrode and the fixed electrode on the rear side need to be adjusted. Compared to conventional accelerometers, the servo-type accelerometer of this invention is extremely easy to select between differential and non-differential types. Here, we compare the non-differential embodiment 1 (… Figure 1 ) and differential implementation 10 ( Figure 23 , Figure 24 To make it differential, simply add a rear movable side electrode 310b to the drive unit 331 and install a rear fixed side electrode 311b on the rear unit 332. Therefore, the choice from non-differential to differential does not result in a significant increase in cost.

[0315] Furthermore, the adjustment of the electrode gap during the final stage of mass production—specifically, the adjustment of the gap between the rear movable side electrode 310b and the rear fixed side electrode 311b—can be performed independently of the front side. For example, the rear side adjustment can be performed after the front side adjustment is completed.

[0316] (ii) Explanation of drift / noise reduction effect

[0317] The following explanation, based on a comparison with existing methods, illustrates the drift / noise reduction effect of the sensor in this embodiment. Figure 25 This indicates the existing type of accelerometer (refer to...) Figure 54 The relationship between electrode output, noise and drift, and sensor acceleration output is shown in Figure 25. Electrode output is obtained by detecting the electrostatic capacitance determined by the gap between movable electrode 24 and fixed electrode 25. Graph A, representing noise and drift, is a sine wave with a small positive bias applied. Graph C, representing sensor acceleration output, is the result of applying noise and drift (Graph A) to the electrode output (Graph B).

[0318] Furthermore, in the active vibration damping table, absolute velocity feedback and absolute displacement feedback were implemented to obtain vibration damping performance in the low-frequency region. To obtain the absolute velocity signal, the acceleration signal needs to be integrated once, and to obtain the absolute displacement signal, the acceleration signal needs to be integrated twice. Figure 25Curve D represents the absolute velocity output obtained by integrating the sensor acceleration output (curve C) once using full integration. The velocity signal, superimposed with noise, diverges due to drift. To address this issue, in practical active vibration damping systems, full integration of 1 / s is not used. Instead, an approximate velocity signal is obtained by integrating the accelerometer output using incomplete integration of 1 / (s+a). Alternatively, an approximate displacement signal is obtained by integrating the velocity signal using the same integrator. However, the phase delay angle of the signal obtained through incomplete integration in the low-frequency region cannot be the same as that obtained with full integration. Consequently, an accurate negative feedback signal cannot be obtained. Furthermore, phase delay and increased gain occur in the low-frequency region, leading to problems such as insufficient vibration damping characteristics.

[0319] Figure 26 This indicates the relationship between the outputs of the two electrodes, noise and drift, and the sensor acceleration output in the case of the accelerometer in this embodiment.

[0320] Front electrode output B f It is obtained by detecting the electrostatic capacitance determined by the gap between the movable electrode 310a and the fixed electrode 311a, and the output B of the rear electrode is... r It is obtained by detecting the electrostatic capacitance determined by the gap between the movable electrode 310b and the fixed electrode 311b. By applying noise and drift to the outputs of these electrodes, the front electrode output B... f →C f The rear electrode outputs B. r →C r As a result, the acceleration output C of the differential sensor... s This results in a waveform that eliminates noise and drift. Furthermore, the absolute velocity signal D and the absolute displacement signal (not shown), which are fully integrated over the acceleration output, do not diverge. Therefore, when the accelerometer of this embodiment is applied to an active vibration damping stage, in addition to the effects of improved sensor sensitivity (e.g., improved stage positioning accuracy), a significant improvement in vibration damping characteristics in the low-frequency region is also obtained.

[0321] (Eleventh Implementation Method)

[0322] Figure 27 This is a front cross-sectional view of the differential servo-type accelerometer sensor according to Embodiment 11 of the present invention. Similar to Embodiment 10, a differential electrostatic capacitive sensor is constructed by providing electrodes for detecting electrostatic capacitance at both the left and right locations. Furthermore, similar to the ninth embodiment, the front permanent magnet is composed of a segmented magnet magnetized radially, and the magnetic connection portion is also composed of a segmented magnet magnetized radially and a fixed coil.

[0323] 801 is the front permanent magnet, 802 is the rear permanent magnet, 803 is the pole piece, 804 is the gap in the pole piece, 805 is the front disk, 806 is the rear disk, 807 is the front movable electrode, 808 is the front fixed electrode, 809a is the front panel, 809b is the rear panel, 810 is the front central plate, 811 is the front fastening member, 812 is the coil-side yoke, 813 is the coil frame, 814 is the front coil, and 815 is the rear coil. 816 is the front outer peripheral support ring, 817 is the front inner peripheral support ring, 818 is the front end face of the pole piece, 819 is the rear end face of the pole piece, 820 is the outer peripheral support ring of the rear disk, 821 is the coil mounting part that serves as the inner peripheral surface of the coil-side yoke, and 822 is the magnetic gap formed between the coil mounting part and the two permanent magnets. 823 is the rear movable electrode, 824 is the rear fixed electrode, 825 is the rear central plate, 826 is the rear fastening component, and 827 is the rear inner circumferential support ring.

[0324] The above describes two embodiments of the differential sensor. The structure of the actuator section of this differential sensor can be adapted to the scheme shown in the other embodiments of the present invention (linear motion type MM type).

[0325] (Twelfth Embodiment) Swing Type (1)

[0326] Figure 28 This diagram illustrates the swing motion servo-type accelerometer sensor according to Embodiment 12 of the present invention. Figure 28 (a) is a front sectional view. Figure 28 (b) is a schematic view of the side of the oscillator, which is a component of the sensor. Since the servo-type accelerometer of this embodiment is configured symmetrically on both sides, including the magnetic circuit of the permanent magnet, the components on the right side will be described first.

[0327] 901a is a permanent magnet, 902a is the front pole piece, 903a is a cylindrical void formed to reduce the weight of the front pole piece, 904a is the rear pole piece, 905a is the coil-side yoke, 906a is the electromagnetic coil, 907a is the coil frame, and 908a is a protrusion formed on the inner surface of the coil-side yoke. The front pole piece 902a and the rear pole piece 904a are movable yokes. 909 is an oscillator made of a non-magnetic and conductive material. This oscillator is constructed of a cantilever beam with one end fixed and the other end free, and a movable part is provided on the free end side of the cantilever beam. 910 is a shell with a cylindrical cavity in the upper part. This shell is made of a non-magnetic material. 911a is a plate member formed of insulating material at the lower end of the oscillator. The oscillator is fixed while being held between plate members 911a and 911b. 912 is a hinge portion. This hinge portion determines the overall spring stiffness of the oscillator during its oscillating motion. 913a is a movable side electrode formed on the oscillator, and 914a is a fixed side electrode. An electrically insulating covering film (not shown) is formed on the wall surface of the fixed side electrode that is in contact with the housing 910. The oscillator 909, made of conductive material, also serves as a common grounding wire connecting the detection signal of the electrostatic capacitance between the left and right electrodes to the control circuit. 915a is the coil-facing surface of the electrode 902a, and 916a is the coil mounting surface. A radially oriented magnetic gap 917a is formed between the coil-facing surface 915a and the coil mounting surface 916a. An annular gap 918a, consisting of a narrow gap, is formed between the protrusion 908a of the coil-side magnetic yoke and the rear electrode portion 904a. Similar to the first embodiment described above, a closed-loop magnetic circuit (not shown) is formed by "permanent magnet 901a → front pole piece 902a → magnetic gap 917a → coil-side yoke 905a → annular gap 918a → rear pole piece 904a". The annular gap 918a is set with a gap that is sufficiently small in magnetic resistance compared to the magnetic gap 917a. The annular gap is a magnetic connection part used to form a closed-loop magnetic circuit in a magnetic circuit using a permanent magnet. The signal lead between the transceiver coil 906a and the externally located control circuit is the same as in the first embodiment described above, and is provided using a through hole formed in the coil-side yoke 905a and the housing 910 (not shown).

[0328] 919a is a convex-shaped member formed of insulating material, located on the upper part of the oscillator 909 and bonded to it. This convex-shaped member 919a is bonded and fitted to the front electrode portion 902a. Because the convex-shaped member is made of insulating material, the front electrode portion 902a and the oscillator 909 maintain electrical insulation. 920 is a control circuit disposed in the lower gap of the housing 910.

[0329] In this embodiment, the oscillator 909 is used as the central axis, and the components are symmetrically arranged on both sides. In the reference numerals of the components such as the permanent magnet 901a and the pole piece 902a, the reference numeral for the right-side component is a, and the reference numeral for the left-side component is b. If we focus on the right-side components, as in the first embodiment described above, the electromagnetic coil 906a is arranged to surround the permanent magnet 901a and the front pole piece 902a connected in series with the permanent magnet from the outer periphery. Furthermore, an annular gap 918a with a sufficiently small magnetic reluctance compared to the magnetic gap 917a is arranged within the closed-loop magnetic circuit. The movable components that can move axially are the permanent magnet 901a, the front pole piece 902a, and the rear pole piece 904a.

[0330] Figure 29 This illustrates an example of the assembly method for the accelerometer according to this embodiment. After integrating the front electrode portion 902a, the permanent magnet 901a, and the rear electrode portion 904a using an adhesive, they are mounted onto the convex member 919a of the oscillator. Furthermore, after mounting the coil frame 907a, which houses the electromagnetic coil 906a, onto the coil-side yoke 905a, it is fitted into the cavity of the housing 910.

[0331] The components of the magnetic circuit can utilize the structure of the linear motion type accelerometer described in the first to eleventh embodiments. For example, the magnetic connection portion may not be an annular gap, but rather a combination of a segmented permanent magnet magnetized in the radial direction and a fixed-side coil.

[0332] Based on a comparison with the existing oscillating accelerometer disclosed in Patent Document 1, the features of this embodiment will be described. In this embodiment, the oscillator 909 can be made of a conductive metallic material. Figure 56 The reason for using non-conductive materials such as quartz glass in the oscillator 590a in the existing oscillating accelerometer shown is that multiple independent signals (coil and electrode signals) need to be transmitted and received between the movable and fixed control circuits of the sensor. A thin film of gold (Au) is deposited on the surface of the quartz glass by sputtering or vacuum evaporation, forming a conductive path for processing multiple independent signals. That is, since it is an MC type, only necessary components and special processing methods are selected. In this embodiment, which is an MM type, the signals transmitted and received from the movable part to the fixed side are simply the common ground of the left and right electrode signals. Therefore, the existing oscillating MC type is not required. Figure 56 The high-cost sputtering equipment required for the production process can be significantly simplified and costs reduced. The aforementioned common grounding connection can be set using the fixing parts 911a and 911b of the vibrator (not shown).

[0333] (Thirteenth Implementation Method)

[0334] Figure 30 This diagram illustrates a swing motion servo-type accelerometer sensor according to Embodiment 13 of the present invention. To simplify Embodiment 12, only one set of electrostatic capacitance detection electrodes is used.

[0335] 951 is a permanent magnet, 952 is the front pole piece, 953 is the rear pole piece, 954 is the coil-side yoke, 955 is the force-applying coil, 956 is the coil frame, and 957 is a protrusion formed on the inner surface of the coil-side yoke.

[0336] 958 is an oscillator made of a non-magnetic, conductive material; 959 is a rear shell of non-magnetic material with a cylindrical cavity at the top; 960 is the fixing part of the oscillator; 961a and 961b are plate members made of insulating material at the lower end of the oscillator. The fixing part 960 of the oscillator is fixed when clamped by plate members 961a and 961b. 962 is a hinge part (elastic deformation part). This hinge part determines the spring stiffness of the oscillator as a whole, which performs oscillating motion. 963 is a movable side electrode formed at the upper end of the oscillator; 964 is a fixed side electrode. The conductive material oscillator 958 also serves as a common grounding conductive path connecting the detection signal of the electrostatic capacitance between the left and right electrodes to the control circuit.

[0337] 965 is a convex member formed of insulating material, located on the upper part of the oscillator 958 and bonded to it. This convex member 965 is bonded and fitted to the front electrode portion 952. Because the convex member is made of insulating material, the front electrode portion 952 and the oscillator 958 can maintain electrical insulation.

[0338] 966 is a magnetic gap portion, and 967 is an annular gap portion. This annular gap portion is positioned such that its magnetic resistance is sufficiently small compared to the magnetic gap portion 966. The annular gap portion is a magnetic connection portion used to form a closed-loop magnetic circuit in a magnetic circuit using a permanent magnet. Similar to the first and twelfth embodiments described above, a closed-loop magnetic circuit (not shown) is formed by "permanent magnet 951 → front pole piece 952 → magnetic gap portion 966 → coil-side yoke 954 → annular gap portion 967 → rear pole piece 953".

[0339] 968 is a rear housing made of non-magnetic material. In the upper part, the central plate 969 and the fixed side electrode 964 are fastened by the fastening member 970. 971 is a control circuit provided in the lower gap of the rear housing 959.

[0340] As described above, in linear motion accelerometers and oscillating motion accelerometers, if the difference in their basic structures is classified by the elastic support method of the movable part, the linear motion type has a spring arranged in the circumferential direction of the movable part's movement direction as the axis. The oscillating motion type, as shown in the twelfth and thirteenth embodiments, uses a cantilever beam with one end as a fixed end and the other end as a free end to support the movable part. The operating principle of both the linear motion and oscillating motion types remains unchanged in detecting the gap between the fixed electrode and the movable electrode. Therefore, the solutions shown in other embodiments of the present invention can be applied in the oscillating motion type. For example, the method of mounting a thermally conductive coil frame shown in the sixth embodiment, and the method of forming a magnetic circuit using segmented magnets magnetized in the radial direction shown in the seventh and eighth embodiments, can also be applied.

[0341] (Fourteenth Implementation)

[0342] Figure 31 This diagram illustrates a servo-type accelerometer according to Embodiment 14 of the present invention, showing a structure in which multiple components constituting the sensor are bolted together. Figures 32-41 This describes the assembly process of the sensor in this embodiment. Existing servo-type MC-type accelerometers, such as... Figure 54 , Figure 56 The example shows a structure constructed using an adhesive bonding method. The reasons are: (1) the component shape is small, and (2) the movable part needs to be lightweight; these are the main reasons. In the case of a linear motion accelerometer, due to the complex structure requiring "cutting / insulating / welding" of the disc springs supporting both ends of the movable part, a structure based on bolt fastening is difficult. When a product is constructed using an adhesive bonding method, if it is a defective product during the quality evaluation stage of mass production, the main body of the product must be discarded.

[0343] This embodiment applies a method of fastening extremely small bolts (M0.5 to M1.0 mm) used in specialized fields such as watchmaking to a servo-type accelerometer composed of tiny components. The outer diameter of the servo-type accelerometer using this invention is approximately Φ25 mm, smaller than the outer diameter of a 500 yen unit. The reason for applying the bolt fastening method in this embodiment is that it focuses on the MM-type characteristics of the component structure, which simplifies the moving parts by eliminating the need for extremely fine wire processing. The accelerometer of this embodiment can reuse multiple components, significantly improving the yield rate during mass production. Furthermore, in the case of adhesive bonding, the thickness of the adhesive between the bonded components and its unevenness become factors that reduce assembly accuracy. With the bolt fastening method, high assembly accuracy can be ensured as long as the machining accuracy of each component is achieved. Moreover, no operator skill is required, thus reducing deviations in product performance.

[0344] (1) Implementation method: Overall structure of the sensor

[0345] exist Figure 31 In this design, 751 is a permanent magnet with a hollow portion, 752 is a front pole piece, 753 is a cylindrical gap, 754 is a rear pole piece, 755 is a coil-side yoke, 756a is a force-applying coil, 756b is a verification coil, and 757 is a protrusion formed on the rear inner surface of the coil-side yoke. 758 is a front plate, 759 is a rear plate, 760 is a movable side electrode, 761 is a fixed side electrode, 762a is a front panel, 762b is a rear panel, 763 is a central plate, and 764 is a fastening member made of a non-conductive material for the fixed side electrode and the front panel.

[0346] 765 is the coil frame, 766 is the coil frame mounting portion formed on the inner surface of the coil-side yoke, and 767 is the coil-facing surface, which serves as the outer surface of the front pole piece. A radially oriented magnetic gap 768 is formed between the coil-facing surface 767 and the coil frame mounting portion 766. An annular gap (magnetic connection portion) 769, consisting of a narrow gap, is provided between the protrusion 757 of the coil-side yoke and the rear pole piece 7544.

[0347] 770 is the inner circumferential side disc support member, and 771 is the outer circumferential side disc support member. Both disc support members 770 and 771 are made of non-conductive material (insulating material). 772 is a ring-shaped nut made of metal, installed on one end face of the inner circumferential side disc support member 770. The bolts used to fasten the various components will be described below.

[0348] (2) Function of each fastening bolt

[0349] Bolt 773a is used to fasten the movable electrode 760, the inner peripheral side plate support member 770, and the ring nut 772. The front side plate 758 is clamped between the movable electrode 760 and the inner peripheral side plate support member 770. Bolt 773b is used to fix the outer peripheral side plate support member 771 to the coil-side yoke 755. As described later, the front side plate 758 is bonded and fixed to the outer peripheral side plate support member. Therefore, bolt 773b serves to fix the outer peripheral end of the front side plate 758.

[0350] Bolt 773c secures the front pole piece 752, permanent magnet 751, and rear pole piece 754. Bolt 773d secures the outer periphery of the rear disc 759 and the coil-side yoke 755. Bolt 773e secures the inner periphery of the rear disc 759 and the rear pole piece 754. Bolt 773f secures the coil frame 765 to the coil-side yoke 755. Bolt 773g secures the front panel 762a and the rear panel 762b.

[0351] (3) Description of the assembly process The assembly process will be described below in stages.

[0352] (3-1) Assembly preparation stage

[0353] The basic assembly process of the sensor in this embodiment is bolt tightening. However, it is not necessary to bolt all components. For example, for components that require electrical insulation, the conductive material (metal) and the insulating material (ceramic, etc.) can be integrated in advance using an adhesive. Figures 32-34 In the assembly preparation stage, in Step 1, the outer peripheral side plate support member 771 and the front side plate 758, made of ceramic, are bonded and fixed at the location indicated by the dashed circle A. In Step 2, the inner peripheral side plate support member 770, made of ceramic, and the annular nut 772, made of metal, are bonded and fixed at the location indicated by the dashed circle B. In Step 3, the integrated component consisting of the inner peripheral side plate support member 770 and the annular nut 772 is bonded and fixed to the opening of the front electrode portion 752.

[0354] (3-2) Installation of coil frame and treatment of coil lead wires

[0355] Figures 35-36 This describes the process of installing the coil bobbin 765 and processing the coil leads. 774 is the lead of the force-applying coil 756a and the calibration coil 756b; 775 is an inner groove formed on the inner surface of the coil-side yoke 755; 776 is a through hole formed in the radial direction of the coil-side yoke; and 777 is an outer groove formed on the outer periphery of the coil-side yoke. The inner groove 775, the through hole 776, and the outer groove 777 are... Figure 31 There is no record of it.

[0356] In step 4, while inserting the coil bobbin 765 into the coil-side yoke, the front end of the coil lead 774 is led outward using the inner groove, the through hole, and the outer groove. In step 5, the coil bobbin 765 is fastened to the coil-side yoke 755 using bolts 773f.

[0357] (3-3) Treatment of lead wires for movable side electrode and installation of front electrode plate

[0358] Figure 37 This indicates the shape of the front disc 758 applied in this embodiment. In the dashed line D, 778 is the protruding end, and 779 is the through hole formed at the protruding end. In step (Step) 6, Figure 38 (a) is a diagram showing the state in which the front pole piece 752 is installed inside the coil-side yoke 755. Figure 38 (b) is a partial enlarged view of the dashed line E. 780 is an electrode groove formed on the outer peripheral surface of the coil-side yoke 755, and 781 is the lead wire of the movable-side electrode 760. 782 indicates that, with the cover of the lead wire 781 removed, the lead wire 781 is electrically connected to the front disk 758 via the through hole 779. The method of electrical connection can be welding, conductive adhesive, etc. 783 are multiple through holes formed in the front disk 758, the inner diameter of which is larger than the head 773bH of the fastening bolt 773b.

[0359] As described above, the front disc 758 and the outer peripheral disc support member 771 are bonded and fixed. Therefore, if the outer peripheral disc support member 771 is fixed to the coil-side yoke 755 by the fastening bolt 773b, electrical insulation can be maintained between the front disc 758 and the coil-side yoke 755. The head 773bH of the fastening bolt 773b remains non-contact with the through hole 783. The movable side electrode 760 is fastened to the annular nut 772 while the front disc 758 and the inner peripheral disc support member 770 are clamped by the fastening bolt 773a. As described above, the disc support member 770 and the annular nut 772 are pre-integrated using adhesive.

[0360] (3-4) Final assembly stage

[0361] Step 7 represents the process of fastening the permanent magnet 751 and the rear plate 759. For example... Figure 39 As shown, the permanent magnet 751 is fastened to the front pole piece 752 via the rear pole piece 754 by fastening bolt 773c. The rear plate 759 is fastened to the coil-side yoke 755 and the rear pole piece 754 by fastening bolts 773d and fastening bolt 773e.

[0362] Step 8 indicates the procedure for installing the sensor storage box in the final stage. For example... Figure 40 As shown, the fixed-side electrode 761 is temporarily fixed to the front panel 762a by the fastening member 764. The front panel 762a is fastened to the rear panel 762b by the fastening bolt 773g in a manner that accommodates the coil-side magnetic yoke 755.

[0363] Furthermore, the structure for extending the signal line 781 of the electrode and the lead wire 774 of the coil to the outside is not limited to this embodiment as a bolt-fastening structure. It can also be applied in other embodiments as an adhesive method.

[0364] (Fifteenth Implementation)

[0365] In the above embodiment, a bolt-fastening method was applied up to the final assembly stage, except for the initial preparation stage. This embodiment, by applying an adhesive method in the final assembly stage, adjusts the gap between the electrodes on the movable and fixed sides to an optimal value while simultaneously measuring the electrostatic capacitance. In other words, it is a countermeasure that absorbs all accumulated errors in the final process.

[0366] Figure 41 This indicates the two units that are fastened. Figure 41 (a) is called the fixed-side electrode unit 850. Figure 41 (b) is called the movable side electrode unit 851. Figure 42 This is a diagram showing the state in which the two units are joined together using an adhesive.

[0367] Hereinafter, only the parts specifically described in the fifteenth embodiment will be explained. 852 is a movable side electrode, 853 is a fixed side electrode, 854a is a front panel, 854b is a rear panel, 855 is a central plate, and 856 is a fastening member made of a non-conductive material for the fixed side electrode and the front panel. 857 is a coil-side magnetic yoke, 858a is a movable unit-side fitting element, 858b is a fixed unit-side fitting element, and 859 is a bolt for fastening the rear panel and the coil-side magnetic yoke. 860a is a movable unit-side mating surface, 860b is a fixed unit-side mating surface, and 860bc is a tapered portion formed on the fixed unit-side mating surface. The movable unit-side fitting element 858a and the fixed unit-side fitting element 858b form a fitting structure.

[0368] exist Figure 42In this embodiment, 861 is an adhesive applied between the movable unit side mating surface 860a and the fixed unit side mating surface 860b. In this embodiment, an ultraviolet-curable adhesive is used. This adhesive is cured by irradiation with LED light. Therefore, in the initial stage of LED light irradiation, the two units, with their radial movement restricted by the mating elements 858a and 858b forming the mating structure, can move relative to each other in the axial direction. The electrode gap δ z (The gap between the movable side electrode 852 and the fixed side electrode 853) is determined based on the measured value of the electrostatic capacitance. For example, with the fixed unit 851 fixed, the movable unit 850 is moved in the axial direction (arrow C). When the electrostatic capacitance reaches the target value, if the adhesive is cured by irradiating it with LED light, the two units can be secured.

[0369] In the initial stage of fastening the two units ( Figure 41 (b) In the state of the movable side electrode unit 851 alone, the actuator function of the sensor can be measured and evaluated. For example, if a displacement sensor for detecting the axial displacement of the movable side electrode 852 is separately configured, the frequency response characteristics and transient response characteristics relative to the current of the force coil 756a can be evaluated. Based on the evaluation results, the characteristics of the bolt fastening method can be effectively utilized to facilitate the replacement / reuse of each component.

[0370] Besides adjusting the gap δ between the two electrodes z In addition to the methods described above, the tilt angle δ between the two electrodes can also be used. θ The fastening member 856 is used in the adjustment. In this case, the fastening member 856 may also be applied with a UV-curable adhesive, for example. The δ of the gap between the two electrodes shown in this embodiment is adjusted. z (or δ) θ The method can also be applied to other embodiments of the present invention.

[0371] (Sixteenth Implementation)

[0372] Figure 43This is a front cross-sectional view of the differential servo-type accelerometer according to Embodiment 16 of the present invention. The movable part is a moving / coil type (MC type) with coil movement. 51 is a permanent magnet, 52 is an electrode portion, 53 is an electrode protrusion, 54 is a permanent magnet-side yoke, 55 is a coil-side yoke, 56a is a force-applying coil, 56b is a calibration coil, 57 is a coil frame, 58 and 59 are coil frame support members, 60 is a front disc, 61 is a rear disc, 62 is a front connecting member between the front disc 60 and the coil-side yoke 55, and 63 is a rear connecting member between the rear disc spring 61 and the coil-side yoke 55. A radially oriented magnetic gap 64 is formed between the outer periphery of the electrode portion 52 and the inner periphery of the coil-side yoke 55. 64a is a permanent magnet-side gap, and 64b is a yoke-side gap. The closed-loop magnetic circuit formed by “permanent magnet 51 → pole piece 52 → magnetic gap 64 → coil side yoke 55 → permanent magnet side yoke 54” is the same as that of the existing MC-type servo-type accelerometer.

[0373] 65 is the movable first electrode (electrode surface Sa), 66 is the movable second electrode (electrode surface Sb), 67 is a cylindrical member, and 68 is a fixed-side electrode support member made of non-conductive material. 69 is the fixed-side first electrode (electrode surface SA) formed on the fixed-side electrode support member 68, 70 is the fixed-side second electrode (electrode surface SB), 71 is a first gap formed by the movable first electrode 65 and the fixed first electrode 69, and 72 is a second gap formed by the movable second electrode 66 and the fixed second electrode 70. The movable first electrode 65 and the movable second electrode 66 are bonded and fixed through the cylindrical member 67. Furthermore, the movable first electrode 65 is bonded and fixed to the front disc spring 60 in its outer periphery. If the electrostatic capacitance signal A is defined by the gap of the first gap 71 and the electrostatic capacitance signal B is defined by the gap of the second gap 72, then the two electrostatic capacitance signals A and B are in opposite phase. That is, a differential sensor is constructed by independently detecting two electrostatic capacitance signals A and B. 73a is an axial conductor line that transmits the electrostatic capacitance signal B in the axial direction, and 73b is a radial conductor line that transmits the signal in the radial direction. The two electrostatic capacitance signals A and B, as well as the current flowing through the force coil 56a and the detection coil 56b, are transmitted to the fixed side via the front disc spring 60 and the rear disc spring 61. The two disc springs are divided in the circumferential direction, forming multiple independent signal transmission paths (not shown). 74 is the front panel.

[0374] exist Figure 43In the diagram, the portion indicated by the double-dotted line AA represents the actuator section that drives the two movable electrodes 65 and 66 axially. In this embodiment, an MC type (moving / coil type) actuator section is used. The MM type (moving / magnet type) shown in the above embodiment can also be used instead of the MC type. Alternatively, any actuator of the MC, MM, MI, or other types can be used.

[0375] (Seventeenth Implementation)

[0376] The above embodiment constructs two sets of electrostatic capacitive sensors by clamping a fixed-side electrode support member between two movable electrodes. Conversely, even with only a movable electrode member clamped between two fixed-side electrode support members, two sets of electrostatic capacitive sensors can be constructed. Figure 44 In this design, 151 is a first fixed-side electrode support member, 152 is a second fixed-side electrode support member, 153 is a movable-side electrode member, 154 is a cylindrical connecting member, 151a is a fixed-side first electrode (electrode surface Saa) formed on the surface of the first fixed-side electrode support member 151, and 153a is a movable-side first electrode (electrode surface SAA) formed on the surface of the movable-side electrode member 153. 152a is a fixed-side second electrode (electrode surface Sbb) formed on the surface of the second fixed-side electrode support member 153, and 153b is a movable-side second electrode (electrode surface SBB) formed on the surface of the movable-side electrode member 153. 155 is a first gap formed by the movable-side first electrode 153a and the fixed-side first electrode 151a, and 156 is a second gap formed by the movable-side second electrode 153b and the fixed-side second electrode 152a.

[0377] If the electrostatic capacitance signal A is defined by the gap of the first gap 155 and the electrostatic capacitance signal B is defined by the gap of the second gap 156, then the two electrostatic capacitance signals A and B are out of phase. That is, similar to the above embodiment, a differential sensor is constructed by independently detecting the two electrostatic capacitance signals A and B. The double-dotted line BB in the same figure is the actuator section that uses the connecting member 154 as the output. This actuator section BB can also use an MC type, MM type, or any type of actuator.

[0378] (Eighteenth Implementation)

[0379] Figure 45 This refers to the servo-type accelerometer sensor of Embodiment 18 of the present invention. Figure 45 (a) indicates the shape of the front disc. Figure 45 (b) represents a front sectional view of the accelerometer sensor body. Figure 45(c) indicates the shape of the rear disk. In the magnetic connection section (dashed circle BB) that forms the closed-loop magnetic circuit, insufficient component and assembly precision is achieved. Due to eccentricity of the shaft core on the fixed and movable sides, a centrifugal magnetic attraction force is generated (same as F in the figure). r This embodiment describes a disk shape that minimizes this effect.

[0380] 151 is a permanent magnet magnetized axially; 152 is a front pole piece; 153 is a space formed inside the pole piece; 154 is a rear pole piece; 155 is a coil-side yoke; 156 is a force-applying coil; 157 is a protrusion formed on the inner surface of the coil-side yoke; 158 and 159 are front and rear disks supporting the movable part, respectively. 160 is a movable side electrode; 161 is a fixed side electrode; 162a is a front panel; 162b is a rear panel; 163 is a central plate; 164 is a fastening member; and 165 is a magnetic gap. The aspect where a narrow annular gap 166 is provided between the protrusion 157 of the coil-side yoke and the rear pole piece 154 is the same as in the above embodiment. 167 is an outer peripheral support ring; and 168 is an inner peripheral support ring. The closed-loop magnetic circuit, as shown by the dashed arrows, is formed via "permanent magnet 151 → front pole piece 152 → magnetic gap 165 → coil-side yoke 155 → protrusion 157 → annular gap 166 → rear pole piece 154 → permanent magnet 151," and is the same as in the above embodiment. The shape of the rear pole piece 154 differs from the above embodiment. 169 is a protrusion formed at the center of the rear pole piece, 169a is a central protrusion used to position the center of the rear disk, and 170 is a gap.

[0381] In this embodiment, such as Figure 45 (a) and Figure 45 As shown in (c), the shape of the disc supporting the movable part differs significantly between the front and rear sides. The front disc ( Figure 45 (a) is a helical spring having a peak 158a and a groove 158b that are long in the circumferential direction. In contrast, the rear disc ( Figure 45 (c) is composed of six peaks 159a perpendicular to the circumferential direction and grooves 159b between the peaks. This is to reduce the axial stiffness K of the rear disc. a The width of the peak 159a is set to be relatively narrow, and the support interval R between the center and the outer periphery is set to be sufficiently long. The plate thickness of the rear disc is sufficiently thin compared to the front disc. Since the rigidity of the disc is inversely proportional to the cube of the plate thickness, for example, if the plate thickness is 1 / 2, the rigidity is 1 / 8. The axial rigidity k of the rear disc... a Similar in size to the front disc, with radial stiffness K rExtremely high. That is, in the magnetic connection part BB, when the shaft cores on the fixed side and the movable side are eccentric, the centripetal rigidity k is sufficiently high relative to the magnetic attraction Fr generated in the centrifugal direction. r This allows the movable shaft core to be held at a position with the same radius. Here, the eccentricity of the movable shaft core relative to the fixed shaft core is defined as δ. r In δ r When F = 0, the magnetic attraction force in the centrifugal direction is F r =0. However, in generating δ r In the case of eccentricity > 0, the magnetic attraction F r and eccentricity δ r Further increase. The magnetic attraction F in the centrifugal direction r With eccentricity δ r The relationship is nonlinear, and the axis placed on the movable side in the magnetic field is in an unstable equilibrium condition. Here, if defined as K... mr =F r / δ r Then K mr It is the negative spring stiffness formed by the magnetic circuit. Here, is defined as F. r >0 and K mr >0. Therefore, if the centripetal stiffness of the disk is chosen as K... r >K mr Then the magnetic connection part BB can maintain a stable state. The shape of the rear disk is not limited to the shape shown in this embodiment. If the radial direction rigidity k r Relative to axial stiffness k a If it is tall enough, it can also be any shape. For example, in the case of a spiral shape, if the spiral angle α (refer to...) Figure 45 (a) is defined as the slope of the curve relative to the circumferential direction, and can also be a curve with a sufficiently large angle α. If it is within the range of 45 ≤ α ≤ 90 degrees, then a sufficiently high radial stiffness k is obtained. r The shape of the front disc is not limited to the spiral curve shown in this embodiment. As long as the thickness of the disc is thin enough and can be controlled within the elastic limits of the material, it can be similar to the shape of the rear disc in this embodiment.

[0382] In this embodiment, Figure 45 The rear disc shown in (c) uses precipitation-hardening high-strength stainless steel (SUS631). This material undergoes precipitation hardening after cold rolling, resulting in the formation of intermetallic compounds containing fine Al particles within the martensite, thus yielding a stainless steel with very high hardness. The use of this special steel is for the following reasons: to maintain a small disc outer diameter and reduce axial stiffness k. a This necessitates thinning the plate and narrowing the peak width. Therefore, compared to Figure 45Compared to the case shown in (a) where the helix angle α is sufficiently small, a larger stress needs to be generated. The high-strength stainless steel used has approximately three times the tensile strength (1400–1500 N / m) compared to ordinary steels such as SUS304. 2 And spring limit values. Alternatively, it can be stainless steel such as SUS632J1, as long as the tensile strength is >1000 N / m. 2 Therefore, these insights and countermeasures can be applied to the present invention. The above-mentioned insights and countermeasures related to the disk shape and the strength of the disk material shown in this embodiment can be applied to all embodiments of the present invention.

[0383] (II) Moving / Yoke Type (MY Type) Accelerometer

[0384] The embodiments of the present invention described above propose an MM-type scheme for permanent magnet movement, replacing the existing MC-type scheme for coil movement. Returning to the original point, the focus is on the magnetic circuit of the actuator section constituting a servo-type accelerometer, which forms a closed loop consisting only of three elements: a "permanent magnet," a "coil," and a "yoke." The proposal of this embodiment is whether it is possible to construct a servo-type accelerometer by fixing the "permanent magnet" and the "coil" together while only moving the "yoke." That is, a moving / yoke type (MY type (provisional name)) scheme, which should also be referred to as a "third linear motor," is proposed. The MY type accelerometer is characterized by...

[0385] (1) Similar to the MC type, it achieves lightweighting of the movable part.

[0386] (2) Like the MM type, it does not require the processing of extremely fine wires with coils.

[0387] That is, it can eliminate the disadvantages of both MM and MC types, and combine the advantages of both.

[0388] (Nineteenth Implementation)

[0389] Figure 46This is a front cross-sectional view of the MY-type servo-type accelerometer according to Embodiment 19 of the present invention. 851 is a permanent magnet magnetized axially; 852 is a fixed-side pole piece (pole-side yoke); 852a is a tapered portion of the fixed-side pole piece; and 852b is a cylindrical portion of the fixed-side pole piece. 853 is a movable-side pole piece (movable-side yoke); 853a is the opposite surface of the cylindrical portion 852b in the fixed-side pole piece. 854 is a space formed inside the movable-side pole piece for weight reduction. 855 is a coil-side yoke; 855a is a permanent magnet-side yoke; 856 is a force-applying coil; and 857 is a bias coil. 858 is the front plate, 859 is the rear plate, 860 is the movable side electrode, 861 is the fixed side electrode, 862a is the front panel, 862b is the rear panel, 863 is the central plate, 864 is the fastening member, 865 is the coil mounting portion in the inner circumferential surface of the coil-side yoke, and 866 is the coil-facing surface in the movable side electrode portion. A radially oriented magnetic gap 867 (first gap) is formed between the coil-facing surface 866 and the coil mounting portion 865. A narrow gap 868 (second gap) (dashed circle B) is provided between the cylindrical portion 852B of the fixed side electrode portion and its facing surface 853a. This dashed circle B is a magnetic connection portion. 869 and 870 are an outer circumferential support ring and an inner circumferential support member made of non-conductive material. In this embodiment, when no current is applied to the force coil 856, and a small axial force is generated in the movable side pole portion 853, the pole portion 853 can be held in a fixed position by allowing a bias current to flow through the bias coil 857. A closed-loop magnetic circuit is formed as shown by the dashed arrow: "Permanent magnet 851 → Fixed side pole portion 852 → Gap portion 868 → Movable side pole portion 853 → Magnetic gap portion 867 → Coil side yoke 855 → Permanent magnet side yoke 855a → Permanent magnet 851".

[0390] The working principle of the sensor in this embodiment is the same as that of the MM type described above. If a current is applied to the force coil 856, the reaction force of the Lorentz force, which is the working principle of a linear motor, acts on the movable side electrode portion 853. The current in the force coil 856 is proportional to the acceleration generated by the external force; therefore, acceleration is measured by detecting the current in the force coil 856. The method for extending the leads of the force coil 856 and the bias coil 857, as well as the method for taking the signal lines of the electrodes out to the outside, is the same as in the embodiment described above. This is achieved by using the sensor described in the first embodiment. Figure 1 (b) or as the fourteenth embodiment based on a bolt-fastening structure. Figure 36 , Figure 38 The same method as (a) can be used. For example... Figure 36As shown, one example is a method of forming an outer groove 777 on the outer periphery of the coil-side yoke 755 and mounting the lead wire of the coil 774 in this groove. The same configuration (not shown) can also be applied in this embodiment and the embodiments described later.

[0391] The features of the MY-type accelerometer of the present invention are summarized as follows.

[0392] (1) The inertial mass of the movable part can be selected within a wide range. In this embodiment, the movable side electrode portion 853 is formed into a cylindrical shape, but by making the cylindrical portion thinner and lighter, the high-frequency performance, which is characteristic of the MC type, can be obtained. If the movable side electrode portion 853 is made into a solid cylindrical shape and the inertial mass is increased, the low-frequency performance, which is characteristic of the MM type, can be obtained. That is, the sensor specification that matches the characteristics required by the object (active vibration damping table, etc.) of which this sensor is applied can be arbitrarily selected according to the shape of the movable side electrode portion 853.

[0393] (2) The performance of the permanent magnet can be selected within a wide range. Since there are no restrictions on the size / shape of the permanent magnet 851, the demagnetization characteristics (holding force H) used as an indicator of the permanent magnet's performance can be selected over a wide range. c saturation magnetic flux density B r Since the permanent magnet has a performance margin, the gap 868 in the magnetic connection part B can be sufficiently increased. Although this gap 868 becomes a magnetic reluctance, the performance of the permanent magnet can be obtained to fully compensate for its losses.

[0394] (3) The coil specifications can also be selected within a wide range. As shown in this embodiment, if the movable side electrode portion 853 is made into a thin cylindrical shape, the increase in inertial mass is minimal even if the movable side electrode portion 853 is lengthened. By utilizing this aspect, the coil housing volume can be sufficiently increased, thus allowing the selection of coil wire diameter and coil turns without increasing resistance. Furthermore, based on the features described in (1) to (3) above, the actuator generating force can be selected within a wide range, thus enabling the realization of an acceleration sensor with excellent sensor sensitivity from low-frequency characteristics to high-frequency characteristics.

[0395] The same applies to this embodiment and the embodiments described later, which are related to the MY-type accelerometer. However, several insights and solutions related to the MM-type accelerometer of the present invention described in section (I) can also be applied to the MY-type. For example, the following can be applied: (i) a structure that uses a non-magnetic and thermally conductive coil frame to dissipate heat from the coil; (ii) a cantilever beam oscillator structure in which one end is a fixed end and the other end is a free end in an elastic member supporting the movable part; (iii) a structure that combines an adhesive method and a very small bolt fastening method in the joint between the components; (iv) a structure in which the inner and outer peripheral sides of the elastic member are fastened to the fixed side with a non-conductive material in order to achieve electrical insulation; (v) a structure that achieves electrical insulation between the movable side electrode and the movable member (electrode); and (vi) a structure that uses a disc spring with sufficiently low axial rigidity made of magnetic material in the magnetic connection part.

[0396] Furthermore, a stacked steel plate (e.g., 0.1-0.2 mm thick) is installed at the locations corresponding to the fixed-side pole piece 852 constituting the magnetic connection part B and the movable-side pole piece 853, which are their opposite surfaces, to overlap a thin annular disk. As used in motors, magnetically controlled bearings, etc., this reduces eddy current losses generated in relatively moving parts, thus providing characteristics advantageous for high-frequency performance. Not limited to this embodiment, the magnetic connection parts in the embodiments described later and in the MM type described in section (I) (e.g., as in the first embodiment) are also applicable. Figure 1 The same applies to part B (not shown).

[0397] (Twentieth Implementation)

[0398] Figure 47 This refers to the MY-type servo-type accelerometer sensor of Embodiment 20 of the present invention. Figure 47 (a) is a front sectional view. Figure 47 (b) is Figure 47 (a) is a cross-sectional view AA. In this embodiment, a magnetic circuit is constructed using multiple segmented permanent magnets that are magnetized in the radial direction.

[0399] 551 is a permanent magnet, 552 is a pole piece (movable side yoke), and 553 is a fixed side yoke. The permanent magnet is composed of segmented permanent magnets 551a, 551b, 551c, and 551d magnetized in the radial direction, and is mounted on the yoke. 554 is the internal space of the pole piece, 555 is the force-applying coil, 556 is the verification coil, 557 is the front plate, 558 is the rear plate, 559 is the movable side electrode, 560 is the fixed side electrode, 561a is the front panel, 561b is the rear panel, 562 is the central plate, 563 is the fastening member, 564 is the coil mounting portion in the inner circumferential surface of the yoke, and 565 is the coil facing surface in the pole piece. A radially oriented magnetic gap 566 (first gap) is formed between the coil facing surface 565 and the coil mounting portion 564. A gap portion 568 (second gap portion) consisting of a narrow gap is provided between the inner peripheral surfaces 567a, 567b, 567c, and 567d of the permanent magnet 551 and the opposite pole piece portion. This gap portion 568 is a magnetic connection portion. 569 and 570 are an outer peripheral support ring and an inner peripheral support member made of non-conductive material. A closed-loop magnetic circuit is formed as shown by the dashed arrow: "Permanent magnet 551 → gap portion 568 → pole piece portion 552 → magnetic gap portion 566 → fixed-side magnetic yoke 553 → permanent magnet 551".

[0400] In this embodiment, a segmented permanent magnet magnet is used, which is magnetized in the radial direction. Therefore, when no current is applied to the force coil 555, no axial electromagnetic force (unbalanced force) is generated in the pole portion 552. Thus, since the pole portion 552 can be kept in the same position, the fine adjustment based on the bias coil current as in the above embodiment is not required.

[0401] Alternatively, a permanent magnet magnetized in the axial direction can be used instead of a segmented permanent magnet magnetized in the radial direction, connecting the permanent magnet and a yoke from which magnetic flux flows in the radial direction. The shape of the yoke can also be the same as that of the segmented permanent magnet described above. The fixed-side yoke can simply be arranged to surround the outer periphery of the pole piece portion (not shown).

[0402] Alternatively, multiple thin, segmented permanent magnets magnetized in the radial direction can be mounted on the outer peripheral surface of the pole piece portion 552, which is opposite to the inner peripheral surfaces 567a to 567d of the permanent magnet 551. That is, it is a hybrid structure of MY and MC types. According to this structure, the magnetic reluctance of the magnetic connection portion (magnetic gap portion 568) can be reduced.

[0403] (Twenty-first implementation method)

[0404] Figure 48This is a front cross-sectional view of the differential servo-type accelerometer based on the MY type according to Embodiment 21 of the present invention. The magnetic circuit is constructed using a permanent magnet of the MY type, magnetized in the radial direction, with both left and right output shafts being open ends. By providing electrodes for detecting electrostatic capacitance at both the left and right locations, a differential electrostatic capacitive sensor can be realized. By making the accelerometer differential, a high-resolution sensor whose output is less susceptible to interference signals such as noise and drift can be achieved.

[0405] 501 is a permanent magnet, 502 is an electrode portion, and 503 is a magnetic yoke. The permanent magnet is composed of multiple segmented permanent magnets magnetized in the radial direction and is mounted on the magnetic yoke. 504 is the internal space of the electrode portion, 505 is a force-applying coil, 506 is a verification coil, 507 is a front plate, 508 is a rear plate, 509 is a front movable electrode, 510 is a front fixed electrode, 511 is a rear movable electrode, 512 is a rear fixed electrode, 513a is a front panel, 513b is a rear panel, 514 is a front central plate, 515 is a rear central plate, 516 is a front fastening member, and 517 is a rear fastening member. 518 is the coil mounting portion in the inner circumferential surface of the magnetic yoke; 519 is the coil-facing surface in the pole portion; 520 is the magnetic gap portion; 521 is the gap portion serving as a magnetic connection portion; 522 and 523 are a front outer circumferential support ring and a front inner circumferential support member made of non-conductive material; 524 and 525 are a rear outer circumferential support ring and a rear inner circumferential support member made of non-conductive material.

[0406] Furthermore, the method for connecting the wires that detect the electrostatic capacitance between the movable electrode and the fixed electrode to the outside is the same as in the above embodiment (not shown).

[0407] The absolute velocity and absolute displacement signals obtained by fully integrating the acceleration output of the differential sensor of the present invention are not prone to divergence. Therefore, when the sensor of the present invention is applied to an active vibration damping table, in addition to the effect of improved sensor sensitivity (e.g., improved positioning accuracy of the stage), a significant improvement in vibration damping characteristics in the low-frequency region is also obtained.

[0408] (III) Other Implementation Methods

[0409] The embodiments (I) and (II) described above are examples of MM-type and MY-type accelerometers consisting of a voice coil that generates a Lorentz force and a permanent magnet. The embodiments shown below utilize an electromagnet that generates a magnetic attraction based on Maxwell stress, rather than a Lorentz force. The aspect of fixing the coil constituting the electromagnet is the same as in embodiments (I) and (II). Furthermore, in that neither the coil nor the permanent magnet moves, but only the yoke forming the closed-loop magnetic circuit moves, this embodiment can also be considered another form of the MY-type described in section (II).

[0410] (Twenty-second implementation method)

[0411] Figure 49 This is a front cross-sectional view of the servo-type accelerometer sensor according to Embodiment 22 of the present invention. The servo-type accelerometer sensor is constructed by combining an electromagnet that generates magnetic attraction and a permanent magnet.

[0412] 601 is a permanent magnet magnetized in the axial direction; 602 is a permanent magnet-side pole piece; 603 is the opposite surface of the pole piece 602 on the permanent magnet side; 604 is the opposite surface of the pole piece side of the permanent magnet; 605 is a space formed inside the pole piece 602; and 606 is a permanent magnet-side yoke. 607 is a coil frame; 608 is the force-applying coil (control coil) of the electromagnet; and 609 is a bias coil. 610 and 611 constitute the electromagnet-side yoke, with 610 being the outer peripheral yoke relative to the core of coils 608 and 609, and 611 being the core-side yoke.

[0413] 612 is the pole piece (movable member side magnetic yoke) on the electromagnet side, 613 is the opposite surface on the central axis side of the pole piece 612, 614 is the opposite surface on the pole piece side of the central axis, and 615 is the space formed inside the pole piece 612.

[0414] 616 is the electromagnet-side housing, 617 is the permanent magnet-side housing, 618 is a movable member made of non-magnetic material, and 619 and 620 are fastening members that clamp the movable member 618 from the left and right. The fastening members are fixed from the left and right by the permanent magnet-side housing and the electromagnet-side housing. 621a and 621b are the movable-side electrode R and the fixed-side electrode R. 622a and 622b are the movable-side electrode L and the fixed-side electrode L. The two electrodes formed on the left and right sides of the movable part constitute a differential acceleration sensor. The imaginary line 623 in the shaft-side yoke 611 and the electromagnet-side housing 616 is a through-channel required when using displacement sensors other than electrostatic capacitive ones (described later in Supplement (3)).

[0415] The permanent magnet side pole piece 602 and the electromagnet side pole piece 612 are made of magnetic material and are fixed left and right at the center of the movable member 618, which is made of non-magnetic material. The electromagnet side forms a closed-loop magnetic circuit through a component including "central shaft 611 → electromagnet side yoke 610 → electromagnet side pole piece 612". The permanent magnet side forms a closed-loop magnetic circuit through a component including "permanent magnet 601 → permanent magnet side pole piece 602 → permanent magnet side yoke 606". As shown in the figure, the attractive force F generated by the permanent magnet 601... m The current always acts on the movable part 618. When the accelerometer is working, current flows through the bias coil 609, holding the movable part 618 at its origin. In this state, if an external force is applied to the movable part as a whole, current flows through the force coil 608, causing the movable part 618 to return to its origin. Since the current in the force coil 608 is proportional to the acceleration generated by the external force, acceleration is measured by detecting the current in the force coil 608.

[0416] In the accelerometer of this embodiment, a magnetic attraction based on Maxwell stress is used to drive the movable part. When comparing the actuator dimensions under the same conditions, the electromechanical conversion efficiency (thrust constant) of Maxwell stress relative to the force generated by the input current is overwhelmingly higher than that of Lorentz force, typically more than 20 times. By utilizing this, the accelerometer of this embodiment can significantly increase the upper limit of the measurable acceleration.

[0417] However, if the upper limit of the measurable acceleration can also be small, a structure combining a Lorentz force actuator and a permanent magnet (not shown) as an embodiment of Section (I) can be used instead of a Maxwell stress actuator.

[0418] (Twenty-third Implementation)

[0419] Figure 50 This is a front cross-sectional view of the servo-type accelerometer of Embodiment 23 of the present invention. The servo-type accelerometer is constructed by combining two electromagnets that generate magnetic attraction based on Maxwell stress in a left-right symmetrical manner.

[0420] The components of this accelerometer are symmetrically arranged, therefore the subscript to the right of the drawing number is designated as 'a', and the subscript to the left is designated as 'b'. First, let's describe the components on the right side. 631a is the coil frame, and 632a is the force-applying coil for the electromagnet.

[0421] The yoke on the electromagnet side is composed of 633a and 634a. 633a is the outer peripheral yoke relative to the core of coil 632a, and 634a is the core-side yoke (central shaft). 635a is a cylindrical portion of a pole piece made of non-magnetic material, 636a is a flat plate portion of a pole piece made of magnetic material (movable member-side yoke), 637a is a housing, 638 is a movable member made of non-magnetic material, and 640a and 640b are fastening members that clamp the movable member 638 from the left and right. The movable member is fastened from the left and right by fastening members 640a and 640b. 641a is a movable side electrode, and 642a is a fixed side electrode. The two electrodes formed on the left and right sides of the movable part constitute a differential acceleration sensor. 643a is the first magnetic pole at the front end of the central shaft, and 644a is the second magnetic pole at the front end of the yoke on the outer peripheral side of the central shaft. A closed-loop magnetic circuit is formed by “central axis 634a → magnetic yoke 633a → second magnetic pole 644a → flat plate portion 636a of pole piece → first magnetic pole 643a → central axis 634a”.

[0422] Furthermore, the shape of the yoke that constitutes the electromagnet, the position of the coil, etc., can be arbitrary as long as a closed-loop magnetic circuit is formed between the yoke and the movable side component.

[0423] When no current is applied to the force coils 632a and 632b of the left and right electromagnets, the attractive force does not act on the movable member 638, and the movable member 638 remains in its original position. If an external force is applied to the movable part as a whole, a reverse current flows through each force coil 632a and 632b, causing the movable part 638 to return to its original position. For example, I R A current equal to I0 + δI flows through the right-side force-applying coil 632a. L A current of I0 - δI flows through the left-side force-applying coil 632b. At this time, the current difference between the left and right sides is ΔI = I. R -I L =2δI. Since the current difference ΔI flowing through each force-applying coil is proportional to the acceleration generated by the external force, the acceleration is measured by detecting this current difference ΔI.

[0424] As described above, the electromechanical conversion efficiency (thrust constant) of the force generated relative to the input current is overwhelmingly higher than that of the Lorentz force due to the Maxwell stress. Therefore, by utilizing this, the accelerometer of this embodiment can measure extremely large accelerations. Furthermore, if the purpose is to measure micro-vibrations, a large force can be generated even with a small number of coil turns, thus enabling a significant miniaturization of the accelerometer, including the actuator.

[0425] (Supplement)(1) Regarding magnetic materials

[0426] The following supplements the common content in the implementation methods described in sections (I) to (III).

[0427] For the magnetic material used in the actuator section of a servo-type accelerometer, electromagnetic stainless steel, pure iron, permalloy, Tufperm, bermite, amorphous materials, etc., can be used. Furthermore, while the components forming the closed-loop magnetic circuit use magnetic materials, non-magnetic materials can be used for the housing, etc., which house the actuator.

[0428] (2) Characteristics of the accelerometer required when mounting an active vibration damping table

[0429] For example, this explains why the accelerometer used in an active air pressure servo vibration damping device, with an overall system response (intrinsic value) of around several Hz to tens of Hz, requires a high resonant frequency of several hundred Hz. In active vibration damping tables, in addition to proportional displacement feedback, acceleration feedback is also used. The application of acceleration feedback is primarily necessary to reduce resonance peaks. Furthermore, as is well known, the system is stable on the Bode plot of the first-order transfer function if the following two conditions are met.

[0430] (i) There is a positive gain margin at the phase intersection.

[0431] (ii) There is a positive phase margin at the gain intersection. By implementing acceleration feedback, the gain increases and the phase is delayed by 180 degrees.

[0432] Therefore, even if the overall system responsiveness (intrinsic value) is around several Hz to tens of Hz, the implementation of acceleration feedback provides a high frequency gain margin and phase margin. Therefore, the accelerometer and air pressure servo valve, as control elements constituting the active vibration damping table, require high resonant frequencies (high-speed response). The higher the resonant frequency f0, the more the phase delay near f = 100 Hz can be reduced. According to multiple experimental results, f0 > 200 Hz is acceptable, but as mentioned above, f0 ≥ 250 Hz is preferred. Furthermore, near f = 100 Hz, if the phase delay ΔΦ p <20deg is the allowable range, but if ΔΦ p ≤10deg is preferred.

[0433] (3) Types of displacement detection units that can be applied to the present invention

[0434] The displacement detection units in the embodiments of the present invention described in sections (I) to (III) represent cases where electrostatic capacitance is used exclusively. However, the feature of the present invention is the inherent effect of a servo-type sensor obtained by applying an actuator structure different from the conventional one. For example,

[0435] (i) Because the processing of extremely fine wires for multiple coil signals is simplified, the yield rate during mass production can be greatly improved.

[0436] (ii) While maintaining the characteristics described in (i) above, high-frequency characteristics can be improved by reducing the weight of the movable part. Alternatively, by selecting the inertial mass of the movable part, an accelerometer that emphasizes either high-frequency or low-frequency characteristics can be realized.

[0437] (iii) By applying differential, the drift / noise of sensor signals can be reduced.

[0438] Therefore, the displacement detection unit that achieves the above-mentioned effects of the present invention is not limited to the electrostatic capacitive type. Figure 51 This illustrates a case where an optical displacement detection unit based on triangulation is used in the displacement detection section, replacing the electrostatic capacitive type. 575 is the actuator section equipped with the drive unit, and 576 is the displacement detection section. The displacement detection section 576 consists of a light source 577, a projection lens 578, a receiving lens 579, and a receiving element 580, as shown in the schematic diagram. The actuator section 575 illustrates a case where the MM-type accelerometer structure described in the above embodiment is applied. 581 is a permanent magnet, 582a is a front pole piece, and 582b is a rear pole piece; 582a and 582b constitute a movable magnetic yoke. 583 is a fixed-side magnetic yoke, 584 is a force-applying coil, 585 is a verification coil, 586 is a front plate, 587 is a rear plate, 588a is a front panel, and 588b is a rear panel. A narrow gap 589, which serves as a magnetic connection, is provided between the inner circumferential surface of the rear pole piece and the opposing fixed-side magnetic yoke. 590 and 591 are an outer circumferential support ring and an inner circumferential support member made of non-conductive material. 592 is a laser, and 593 is a laser reflector disposed on the inner circumferential support member.

[0439] 594 is an opening surface through which the laser formed on the front panel 588a passes. The light-receiving element 580 is called a PSD (Position Sensitive Device), which measures displacement based on the difference in the imaging position on the PSD caused by the change in the position of the laser reflector 593. As an optical displacement unit, CMOS, CCD, orthographic reflection, diffuse scattering, and line beam methods can be used. As a displacement detection method other than optical, linear proximity sensors that utilize the change in inductance of a coil caused by eddy currents generated in the object being measured can also be used.

[0440] exist Figure 51The text describes the application of an optical displacement sensor in an MM-type accelerometer structure, but the MY-type accelerometer structure based on Maxwell stress electromagnets, as described in sections (II) and (III), can also be used. For example, in the nineteenth embodiment... Figure 46 In the case of the MY type, as long as the component equivalent to the inner circumferential support member 870 is used as the laser reflecting surface (equivalent to... Figure 51 (593) is sufficient.

[0441] Or in the twenty-second embodiment Figure 49 In this case, the through channel 623 (represented by imaginary lines) formed on the core-side magnetic yoke 611 and the electromagnet-side housing 616 can be used as the laser channel, and the central axis-side opposing surface 613 of the electrode portion 612 can be used as the laser reflecting surface. Alternatively, an eddy current linear proximity sensor can be installed inside the through channel 623.

[0442] For example, when using an optical displacement unit to make a servo-type accelerometer differential, simply by... Figure 51 The displacement detection unit 576 described therein can also be provided on the right side. In this case, it is sufficient to provide a member equivalent to the inner circumferential support member 591 on the right side of the rear electrode portion 582b and to mount the laser reflector on the rear electrode portion. The same applies to the case where a displacement detection unit other than the electrostatic capacitive type is used in the differential sensor embodiments described in sections (I) to (III). For example, in the MY type of the twenty-first embodiment ( Figure 48 In the case of ), the parts of the inner circumferential support members 523 and 525, which are equivalent to the front and rear sides, can be used as the laser reflecting surface or the detection surface of the eddy current linear proximity sensor.

[0443] Industrial applicability

[0444] According to the present invention, a servo vibration detector can be provided that does not require complex wiring, which can greatly simplify the mass production method and reduce the production cost.

Claims

1. A servo-type vibration detector, characterized in that, include: Fixed components; The movable component is configured to move in a predetermined direction relative to the fixed component, and is configured such that magnetic flux flows inside it; An elastic member supports the movable member in a configuration relative to the fixed member with a gap between them; The displacement detection unit detects the displacement of the movable member in the specified direction; as well as The drive unit, upon detecting a relative displacement of the movable member from its origin position via the displacement detection unit, generates an electromagnetic force that returns the movable member to its origin position. The movable member at least includes a movable side magnetic yoke that forms part of a closed-loop magnetic circuit. The movable component also includes a permanent magnet that forms the closed-loop magnetic circuit. The driving unit includes a force-applying coil fixed to the fixed member. By applying current, the permanent magnet and the movable yoke move in the predetermined direction due to the reaction force of the Lorentz force experienced by the current-flowing conductor in the magnetic field. The force-applying coil is mounted to the coil mounting portion located on the inner circumferential surface of the coil-side magnetic yoke of the fixing member. The force-applying coil is configured such that the pole piece of the movable side yoke, which is connected to the permanent magnet of the movable member in the radial or axial direction, is entirely surrounded from the outer peripheral side.

2. The servo-type vibration detector according to claim 1, characterized in that, The gap portion includes a first gap portion and a second gap portion that form a radial gap between the movable member and the fixed member within the closed-loop magnetic circuit. A coil for generating the Lorentz force is fixedly disposed in the first gap. The second gap is a magnetic connection portion used to allow magnetic flux to flow between the movable member and the fixed member.

3. The servo-type vibration detector according to claim 2, characterized in that, The device comprises a pole piece connected to any one of the magnetic pole faces of the permanent magnet and forming part of a movable magnetic yoke; a coil fixedly disposed on the fixing member with its radially opposite face to the pole piece or the permanent magnet separated by the first gap; and a magnetic connection portion configured to allow magnetic flux to flow between the other magnetic pole face of the permanent magnet and the fixing member. The permanent magnet, the pole piece, the first gap portion, the fixing member, and the magnetic connection portion form a closed-loop magnetic circuit.

4. The servo-type vibration detector according to claim 2, characterized in that, It includes a pole piece portion that forms part of the movable side magnetic yoke, and a coil that is fixedly disposed in the fixed member within the gap between the pole piece portion and the fixed member. The pole piece is disposed between itself and any one of the magnetic pole surfaces of the permanent magnet, separated by the magnetic connection portion. The permanent magnet is fixedly configured to allow magnetic flux to flow between the other magnetic pole face of the permanent magnet and the fixed member, forming a closed-loop magnetic circuit with the permanent magnet, the magnetic connection part, the pole piece part, and the fixed member.

5. The servo-type vibration detector according to claim 3 or 4, characterized in that, The electrode portion is cylindrical in shape.

6. The servo-type vibration detector according to claim 4, characterized in that, It consists of a permanent magnet that is magnetized in the axial direction, a pole piece connected to one magnetic pole face of the permanent magnet, a coil that is fixedly disposed on the inner surface of the fixing member with the radially opposite face of the pole piece separated by a gap, and a magnetic connection portion that is configured to allow magnetic flux to flow between the other magnetic pole face of the permanent magnet and the fixing member.

7. The servo-type vibration detector according to claim 1, characterized in that, Let the mass of the movable part, including the movable side magnetic yoke, be m, and let the mass of the permanent magnet be m. p The lower limit value m of the mass of the movable part min =2m p The sensitivity K of the position sensor will be determined. S Adjusting the gain K C , proportional gain K P The electrical gain determined by the product is set as K. PT Set the force constant of the actuator to K. t Let the resistance of the coil be R. a K T =K PT K t / R a The resonant frequency required by the accelerometer is set to f0, and the upper limit value of the mass of the movable part is m. max =K T / (2πf0) 2 When, set to m min ≤m≤m max The range.

8. The servo-type vibration detector according to claim 2, characterized in that, The magnetic connection part consists of an auxiliary permanent magnet that is magnetized in the radial direction and an auxiliary coil that is fixedly disposed on the inner surface of the fixing member with a gap between the surfaces opposite to the auxiliary permanent magnet in the radial direction.

9. The servo-type vibration detector according to claim 1, characterized in that, The closed-loop magnetic circuit includes a first transmission part and a second transmission part that transmit magnetic flux in the radial direction between the movable member and the fixed member. The first transmission part has a radial gap between the movable member and the fixed member, and the coil for generating the Lorentz force is fixedly disposed within the gap. The second transmission part uses a disc-shaped spring made of magnetic material in which magnetic flux flows in the radial direction to fix the movable member and the fixed member. The disc-shaped spring also serves as the elastic member supporting the movable member.

10. The servo-type vibration detector according to claim 2, characterized in that, The permanent magnet is used as the front permanent magnet, and the coil is used as the front coil. The magnetic connection part is composed of a rear permanent magnet that is magnetized in the radial direction, a pole piece connected to one magnetic pole surface of the rear permanent magnet, and a rear coil that is fixedly disposed on the inner surface of the fixing member across the gap on the radially opposite surface of the other magnetic pole surface of the rear permanent magnet. The front permanent magnet, the gap, the fixing member, the gap, and the pole piece form a closed-loop magnetic circuit.

11. The servo-type vibration detector according to claim 3 or 4, characterized in that, The displacement detection unit includes: A movable side electrode is disposed on the movable member; and The fixed side electrode is fixed to the fixing member in a manner opposite to the movable side electrode. A non-conductive material is sandwiched between the movable side electrode and the pole piece that is connected to any one of the magnetic pole surfaces of the permanent magnet and forms part of the movable side yoke.

12. The servo-type vibration detector according to claim 11, characterized in that, This includes movable side electrodes respectively disposed on two end faces of the movable member, and fixed side electrodes disposed on the fixed member opposite to these movable side electrodes. A differential sensor is constructed by detecting the output difference between two sets of electrostatic capacitance sensors formed between the electrode surfaces of the movable side electrode and the fixed side electrode.

13. The servo-type vibration detector according to claim 11, characterized in that, At the end of the movable member, two plate-shaped movable side electrodes are disposed with a gap between them, and the plate-shaped fixed side electrode is disposed within the gap by being clamped by the two movable side electrodes. A first electrostatic capacitance sensor is formed between the electrode surface (Sa) of the movable side electrode and the electrode surface (SA) of the opposite fixed side electrode, and a second electrostatic capacitance sensor is formed between the electrode surface (SB) on the back side of the electrode surface (SA) and the electrode surface (Sb) of the opposite movable side electrode.

14. The servo-type vibration detector according to claim 11, characterized in that, A plate-shaped movable side electrode is provided at the end of the movable member. Two electrode surfaces (SAA, SBB) are formed on the surface and back of the movable side electrode. Two plate-shaped fixed side electrodes are arranged to clamp the movable side electrode with a gap. A first electrostatic capacitive sensor is formed between one electrode surface (SAA) and the electrode surface (Saa) of the opposite fixed side electrode, and a second electrostatic capacitive sensor is formed between the other electrode surface (SBB) and the electrode surface (Sbb) of the opposite fixed side electrode.

15. The servo-type vibration detector according to claim 1, characterized in that, Also includes: A movable unit, including at least the movable member, and equipped with a movable side electrode; and A fixing unit is equipped with a fixed side electrode configured to face the movable side electrode. The displacement detection unit is configured to detect the electrostatic capacitance formed between the movable side electrode and the fixed side electrode. A fitting structure is formed between the movable unit and the fixed unit, allowing the movable unit and the fixed unit to move axially relative to each other while restricting their relative radial movement. Furthermore, grooves for bonding and fixing the movable unit and the fixed unit are formed on the outer surfaces of the movable unit and the fixed unit.

16. The servo-type vibration detector according to claim 3, characterized in that, The magnetic connection portion is composed of the permanent magnet that is magnetized in the radial direction and the outer peripheral surface of the pole piece that is configured with a gap from the inner peripheral surface of the permanent magnet.

17. The servo-type vibration detector according to claim 3, characterized in that, The magnetic connection portion is composed of a permanent magnet that is magnetized in the axial direction, a pole-side magnetic yoke that is connected to either the N pole or the S pole of the permanent magnet, and an inner peripheral surface of the pole portion that is arranged with a radial gap relative to the outer peripheral surface of the pole-side magnetic yoke.

18. A servo-type vibration detector, characterized in that, include: Fixed components; The movable component is configured to move in a predetermined direction relative to the fixed component, and is configured such that magnetic flux flows inside it; An elastic member supports the movable member in a configuration relative to the fixed member with a gap between them; The displacement detection unit detects the displacement of the movable member in the specified direction; as well as The drive unit, upon detecting a relative displacement of the movable member from its origin position via the displacement detection unit, generates an electromagnetic force that returns the movable member to its origin position. The driving unit includes a coil fixed to the fixed component. The movable member at least includes a movable side magnetic yoke that forms part of a closed-loop magnetic circuit. The displacement detection unit includes: A movable side electrode is disposed on the movable member; and The fixed side electrode is fixed to the fixing member in a manner opposite to the movable side electrode. The displacement of the movable member is detected based on the change in electrostatic capacitance formed between the movable side electrode and the fixed side electrode. The elastic member is made of a disk-shaped conductive material, and at least its outer peripheral side is sandwiched with a non-conductive material and fixed to the fixing member.

19. The servo-type vibration detector according to claim 18, characterized in that, The elastic member is formed of a disk-shaped conductive material, and the inner and outer peripheries of the elastic member are integrated with a thin plate member made of a non-conductive material.

20. The servo-type vibration detector according to claim 18, characterized in that, This includes the fixing member, bolt, and elastic member, all made of a conductive material. The elastic member is bonded and fixed to a thin plate made of non-conductive components. The non-conductive component is fastened to the fixed component by bolts. The head of the bolt is configured to be in non-electrical contact with the elastic member.

21. A servo-type vibration detector, characterized in that, include: Fixed components; The movable component is configured to move in a predetermined direction relative to the fixed component, and is configured such that magnetic flux flows inside it; An elastic member supports the movable member in a configuration relative to the fixed member with a gap between them; The displacement detection unit detects the displacement of the movable member in the specified direction; as well as The drive unit, upon detecting a relative displacement of the movable member from its origin position via the displacement detection unit, generates an electromagnetic force that returns the movable member to its origin position. The driving unit includes a coil fixed to the fixed component. The movable member at least includes a movable side magnetic yoke that forms part of a closed-loop magnetic circuit. It also includes a permanent magnet fixed to the fixing member and forming the closed-loop magnetic circuit. The movable yoke is positioned away from any one of the magnetic pole faces of the permanent magnet, and the movable yoke is disposed within the coil. The drive unit is configured to move the movable magnetic yoke in the predetermined direction by applying current to the coil and utilizing the reaction force of the Lorentz force on the current-flowing conductor in the magnetic field.

22. The servo-type vibration detector according to claim 21, characterized in that, The gap portion includes a first gap portion and a second gap portion that form a radial gap between the movable member and the fixed member within the closed-loop magnetic circuit. A coil for generating the Lorentz force is fixedly disposed in the first gap. The second gap is a magnetic connection portion used to allow magnetic flux to flow between the movable member and the fixed member.

23. The servo-type vibration detector according to claim 22, characterized in that, The device comprises a pole piece connected to any one of the magnetic pole faces of the permanent magnet and forming part of a movable magnetic yoke; a coil fixedly disposed on the fixing member with its radially opposite face to the pole piece or the permanent magnet separated by the first gap; and a magnetic connection portion configured to allow magnetic flux to flow between the other magnetic pole face of the permanent magnet and the fixing member. The permanent magnet, the pole piece, the first gap portion, the fixing member, and the magnetic connection portion form a closed-loop magnetic circuit.

24. The servo-type vibration detector according to claim 22, characterized in that, It includes a pole piece portion that forms part of the movable side magnetic yoke, and a coil that is fixedly disposed in the fixed member within the gap between the pole piece portion and the fixed member. The pole piece is disposed between itself and any one of the magnetic pole surfaces of the permanent magnet, separated by the magnetic connection portion. The permanent magnet is fixedly configured to allow magnetic flux to flow between the other magnetic pole face of the permanent magnet and the fixed member, forming a closed-loop magnetic circuit with the permanent magnet, the magnetic connection part, the pole piece part, and the fixed member.

25. The servo-type vibration detector according to claim 23 or 24, characterized in that, The electrode portion is cylindrical in shape.

26. The servo-type vibration detector according to claim 24, characterized in that, It consists of a permanent magnet that is magnetized in the axial direction, a pole piece connected to one magnetic pole face of the permanent magnet, a coil that is fixedly disposed on the inner surface of the fixing member with the radially opposite face of the pole piece separated by a gap, and a magnetic connection portion that is configured to allow magnetic flux to flow between the other magnetic pole face of the permanent magnet and the fixing member.

27. The servo-type vibration detector according to claim 22, characterized in that, The magnetic connection part consists of an auxiliary permanent magnet that is magnetized in the radial direction and an auxiliary coil that is fixedly disposed on the inner surface of the fixing member with a gap between the surfaces opposite to the auxiliary permanent magnet in the radial direction.

28. The servo-type vibration detector according to claim 21, characterized in that, The closed-loop magnetic circuit includes a first transmission part and a second transmission part that transmit magnetic flux in the radial direction between the movable member and the fixed member. The first transmission part has a radial gap between the movable member and the fixed member, and the coil for generating the Lorentz force is fixedly disposed within the gap. The second transmission part uses a disc-shaped spring made of magnetic material in which magnetic flux flows in the radial direction to fix the movable member and the fixed member. The disc-shaped spring also serves as the elastic member supporting the movable member.

29. The servo-type vibration detector according to claim 22, characterized in that, The permanent magnet is used as the front permanent magnet, and the coil is used as the front coil. The magnetic connection part is composed of a rear permanent magnet that is magnetized in the radial direction, a pole piece connected to one magnetic pole surface of the rear permanent magnet, and a rear coil that is fixedly disposed on the inner surface of the fixing member across the gap on the radially opposite surface of the other magnetic pole surface of the rear permanent magnet. The front permanent magnet, the gap, the fixing member, the gap, and the pole piece form a closed-loop magnetic circuit.

30. The servo-type vibration detector according to claim 23 or 24, characterized in that, The displacement detection unit includes: A movable side electrode is disposed on the movable member; and The fixed side electrode is fixed to the fixing member in a manner opposite to the movable side electrode. A non-conductive material is sandwiched between the movable side electrode and the pole piece that is connected to any one of the magnetic pole surfaces of the permanent magnet and forms part of the movable side yoke.

31. The servo-type vibration detector according to claim 30, characterized in that, This includes movable side electrodes respectively disposed on two end faces of the movable member, and fixed side electrodes disposed on the fixed member opposite to these movable side electrodes. A differential sensor is constructed by detecting the output difference between two sets of electrostatic capacitance sensors formed between the electrode surfaces of the movable side electrode and the fixed side electrode.

32. The servo-type vibration detector according to claim 30, characterized in that, At the end of the movable member, two plate-shaped movable side electrodes are disposed with a gap between them, and the plate-shaped fixed side electrode is disposed within the gap by being clamped by the two movable side electrodes. A first electrostatic capacitance sensor is formed between the electrode surface (Sa) of the movable side electrode and the electrode surface (SA) of the opposite fixed side electrode, and a second electrostatic capacitance sensor is formed between the electrode surface (SB) on the back side of the electrode surface (SA) and the electrode surface (Sb) of the opposite movable side electrode.

33. The servo-type vibration detector according to claim 30, characterized in that, A plate-shaped movable side electrode is provided at the end of the movable member. Two electrode surfaces (SAA, SBB) are formed on the surface and back of the movable side electrode. Two plate-shaped fixed side electrodes are arranged to clamp the movable side electrode with a gap. A first electrostatic capacitive sensor is formed between one electrode surface (SAA) and the electrode surface (Saa) of the opposite fixed side electrode, and a second electrostatic capacitive sensor is formed between the other electrode surface (SBB) and the electrode surface (Sbb) of the opposite fixed side electrode.

34. The servo-type vibration detector according to claim 21, characterized in that, Also includes: A movable unit, including at least the movable member, and equipped with a movable side electrode; and A fixing unit is equipped with a fixed side electrode configured to face the movable side electrode. The displacement detection unit is configured to detect the electrostatic capacitance formed between the movable side electrode and the fixed side electrode. A fitting structure is formed between the movable unit and the fixed unit, allowing the movable unit and the fixed unit to move axially relative to each other while restricting their relative radial movement. Furthermore, grooves for bonding and fixing the movable unit and the fixed unit are formed on the outer surfaces of the movable unit and the fixed unit.

35. The servo-type vibration detector according to claim 23, characterized in that, The magnetic connection portion is composed of the permanent magnet that is magnetized in the radial direction and the outer peripheral surface of the pole piece that is configured with a gap from the inner peripheral surface of the permanent magnet.

36. The servo-type vibration detector according to claim 23, characterized in that, The magnetic connection portion is composed of a permanent magnet that is magnetized in the axial direction, a pole-side magnetic yoke that is connected to either the N pole or the S pole of the permanent magnet, and an inner peripheral surface of the pole portion that is arranged with a radial gap relative to the outer peripheral surface of the pole-side magnetic yoke.

37. A servo-type vibration detector, characterized in that, include: Fixed components; The movable component is configured to move in a predetermined direction relative to the fixed component, and is configured such that magnetic flux flows inside it; An elastic member supports the movable member in a configuration relative to the fixed member with a gap between them; The displacement detection unit detects the displacement of the movable member in the specified direction; as well as The drive unit, upon detecting a relative displacement of the movable member from its origin position via the displacement detection unit, generates an electromagnetic force that returns the movable member to its origin position. An electromagnet is constructed by including a fixed-side magnetic yoke that passes through a coil and a movable-side magnetic yoke that is disposed with a gap between the open end of the fixed-side magnetic yoke and the fixed-side magnetic yoke. The electromagnet is formed by the fixed-side magnetic yoke, the gap, and the movable-side magnetic yoke, and serves as a first attraction force generating unit (A) that attracts the movable member including the movable-side magnetic yoke toward the coil side. Furthermore, by configuring a second attraction generating unit (B) that generates a force in the opposite direction to the first attraction generating unit (A) while clamping the movable member, and controlling the current flowing through the coil, the drive unit is constructed based on Maxwell stress that causes the movable member to move axially.

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