JPH01153904A - Displacement measuring instrument - Google Patents

Abstract

PURPOSE:To simplify the constitution and to obtain the small-sized instrument by constituting a magnetic circuit by using a vibration sensing member and winding a coil around this vibration sensing member. CONSTITUTION:A displacement detection part 40 detects the displacement of the vibration sensing member 46 from a casing 45 corresponding to a displacement quantity and a suppression part suppresses the displacement of the member 46 according to the detection result. Here, a permanent magnet 43 fixed to the casing 45 has both end surfaces magnetized into the N and S magnetic polarities to form an N and an S magnetic poles at the inner peripheral flank parts of magnetic yokes 41 and 42 across them. The member 46 is made of a magnetic material and held freely displaceably in a cylinder axial direction or X direction by a leaf spring 12. Thus, the magnet 43, yokes 41 and 42, and member 46 constitute the magnetic circuit across a gap. On the outer peripheral flank of the member 46, on the other hand, servo coils 47A and 47B are wound around the gap part between the yokes 41 and 42 to constitute the suppression part. Then the coils 47A and 47B are driven according to the detection result of the detection part 40 to damp the displacement of the member 46.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a displacement measuring device, and is particularly suitable for application to a servo-type displacement measuring device that measures minute displacements.

[Summary of the invention]

The present invention provides a displacement measuring device in which a magnetic circuit is constructed using a vibration-sensing member that is conventionally configured separately from a magnetic circuit, and a coil is wound around the vibration-sensing member. The combined structure is simplified, and thus a displacement measuring device that is compact as a whole can be obtained.

[Conventional technology]

Conventionally, in this type of servo-type displacement measuring device, the displacement of the vibration sensing member is detected using an optical method or an electrical method, and the displacement of the vibration sensing member is suppressed and braked based on the detection result. There are some devices designed to measure a desired amount of displacement.

For example, as a displacement measuring device that detects displacement using an optical method, as shown in FIG.
A configuration has been proposed in which the vibration is detected by fixing the displacement detecting section l to the object to be measured (Japanese Patent Application No. 60-23).
No. 5033).

In this case, in the displacement detection unit 1, a vibration sensing member 13 made of a cylindrical weight is supported by a plate spring 12 so as to be freely displaceable in the X direction with respect to a casing 11 fixed to the object to be measured. A light source light beam LAI emitted from a coherent light source such as a laser diode 14 is converted by a collimation lens 15 into an irradiation light beam LA2 made of parallel light, and is irradiated.

A pair of semitransparent mirrors 17 constituting an interference mirror are attached to the vibration sensing member 13 and the mounting member 16 provided so as to face the vibration sensing member 13.
and 18 are provided to face each other, and the irradiation light flux L
By repeatedly reflecting A2 between the semitransparent mirrors 17 and 18, interference light LA3 is formed, and this is emitted to the photodetector element 19 as an interference detection light beam LA4 emitted from the exit side semitransparent 1118.

Thus, as shown in FIG. 6(A), between the semi-transparent mirrors 17 and 18, the light intensity It is irradiated between the minimum value ILL and the maximum value ItU when viewed in the direction of displacement X of the vibration sensing member 13. It is possible to generate interference light LA3 whose wavelength λ/2 changes periodically according to LA2.

(Thus, the interference detection light flux L emitted from the semi-transparent mirror 18
When the vibration sensing member 13 is continuously displaced in the X direction, the light intensity A4 is determined by the position XI? of the semi-transparent mirrors 17 and 18, as shown in FIGS. 6(A) and 6(B). and the distance d between Xl1
The value of the interference light detection signal S, which is sent out from the photodetector element 19, changes in accordance with the change in S. Here, the light intensity (2) of the interference detection light beam LA4 emitted from the semi-transparent mirror 18 can be expressed by the following formula (%). In equation (1), ■ is the light intensity of the irradiation light flux LA2 incident from the semi-transparent mirror 17, λ
is the wavelength, Lo is the displacement amount of the vibration sensing member 13, ω is the frequency, and R is a coefficient depending on the reflectance of the mirror.

From equation (1), the displacement id of the vibration sensing member 13 from the vibration center
is (n=0,l,2...)...(2
), for example, as the distance d increases, the light intensity I becomes 1. From +! . The light intensity changes to increase up to, and when it exceeds this range, the light intensity ■ increases! . From-■.

It changes so that it decreases to.

Utilizing this relationship, the servo circuit section 2 applies a servo control force to the vibration sensing member 13 to suppress the change when the light intensity ■ increases (or decreases) in accordance with a change in the distance d. Accordingly, a servo output that suppresses the displacement of the vibration sensing member 13 within the range (aO-λ/8) to (aO+λ/8) expressed by equation (2) is generated based on the interference light detection signal S1.

That is, the interference light detection signal S is sent to the comparator circuit 21 as a detection input S2 via the input amplifier circuit 20 of the servo circuit section 2.
and is compared with the reference voltage V□□ in the comparator circuit 21.

Here, the reference voltage V□□ is selected so that the center of fluctuation of the servo output S5 becomes a value corresponding to approximately the center level of the dynamic range of the servo circuit unit 2.

The difference voltage ΔV between the detection input St and the reference voltage VIIEFI is provided as an error signal S to the phase shift circuit 22, and its phase shift output S4 is provided to the output amplification circuit 23.

The output amplification circuit 23 generates a servo output S5 corresponding to the error signal S based on the phase-shifted output S4, and supplies this to the servo coil 24 provided in the displacement detection section 1.

The servo coil 24 is grounded via a load resistor 25, and a servo current corresponding to the servo output S flows through the servo coil 24 and the load resistor 25, thereby generating a servo control force in the servo coil 24 and Generates a displacement detection output S at both ends of the resistor 25,
This signal is sent to the output terminal TOUT.

The servo coil 24 is wound around a bobbin 27 fixed to the vibration sensing member 13, and is arranged so as to be magnetically coupled to the magnetic circuit 28.

The magnetic circuit 28 allows the magnetic flux generated from the permanent magnet 29 to pass through the servo coil 24 through the magnetic yokes 30A and 30B, thus applying a servo control force in the direction of pulling back the vibration sensing member 13 according to the polarity of the servo output S. It is done like this.

In this way, the servo coil 24, together with the magnetic circuit 28 and the servo circuit section 2, is connected to the vibration sensing member 13 obtained from the displacement detection section l.
A suppressor is configured to suppress and brake the displacement of the vibration sensing member 13 based on the displacement amount detection result.

In the above configuration, when the vibration sensing member 13 is displaced in the X direction due to the vibration of the object to be measured, the interference light detection signal S (Fig. 2 (B)) changes according to the amount of displacement. , an error signal S representing the change, based on the error signal S
The servo output S, which returns , to 0, is the servo coil 24
and applied to the load resistor 25.

At this time, the servo coil 24 generates a servo control force in the direction of suppressing the displacement of the vibration sensing member 13, and thus, when the error signal S becomes 0, the displacement operation of the vibration sensing member 13 stops, The displacement detection output S corresponding to the servo output S at this time is the output terminal T. . Sent from

By the way, when the vibration-sensing member 13 vibrates within a measurable range, the servo circuit section 2 will cause the semi-transparent mirror 17 to move to the reference position d0 (FIG. 2(B)) when the vibration-sensing member 13 is pulled into servo operation. A servo output S having a magnitude such that the center does not displace by more than ±A/8 is supplied to the servo coil 24, so that the vibration sensing member 13 is connected to the semitransparent mirror 1.
The distance d between 7 and 18 is displaced within a minute range of about ±λ/8 with respect to the wavelength λ of the irradiation beam LA2 (the amount of displacement is 1/1 compared to the amount of displacement in a state where the servo is not operated).
000). In this way, the displacement detection output S6 can have a signal level of a practically sufficient voltage level (for example, about 0 to 10 [■]) corresponding to the acceleration of the vibration sensing member 13.

As a result, according to the conventional configuration, displacement detection is highly sensitive to minute displacements of the object to be measured, and changes linearly enough for practical use as a change in the range of ±λ/8 with respect to the wavelength of the irradiation light beam LA2. Output Sb can be obtained.

[Problem that the invention seeks to solve]

By the way, in this type of displacement measuring device, if the displacement detection section can be made smaller, the influence on the vibration of the object to be measured when the displacement detection section is fixed to the object to be measured can be reduced accordingly. It is believed that the measurement accuracy can be further improved.

Furthermore, if the displacement detection section can be miniaturized in this way, the space required to fix the displacement detection section to the object to be measured can be reduced. It is believed that vibration can be measured and the range of application of the displacement measuring device can be expanded.

In practice, when measuring vibration, three types of displacement detection parts are fixed to the object to be measured so that the vibration sensing member 13 is displaced not only in the X direction but also in the Y direction and two directions perpendicular to this. It is common to simultaneously measure vibrations in each X direction, Y direction, and two directions, and it is necessary to prepare a large space in order to fix the displacement detection section to the object to be measured.

The present invention has been made in consideration of the above points, and it is an object of the present invention to simplify the configuration of the displacement detecting section and to propose a displacement measuring device that is compact in size as a whole.

[Means for solving problems]

In order to solve this problem, in the present invention, the magnetic circuit and the vibration-sensing member 46 are shared, that is, the vibration-sensing member 46 is configured to be displaced relative to the case 45 according to the amount of displacement, and the vibration-sensing member 46 is The vibration of the violently vibrating member 46 is based on the displacement detecting section 14.15.17.18.19 configured to detect the displacement of the member 46 and the detection result S of the displacement detecting section 14.15.17.18.19. Suppression unit 2.4 that suppresses and brakes displacement
1.42.43.45.47A, 47B, the suppressor 2.41.42.43.
45. 47A and 47B are magnetic circuits formed by a permanent magnet 43 and a vibration sensing member 46 fixed to the case 45;
On the magnetic path of the magnetic circuit formed by the permanent magnet 43 and the vibration sensing member 46, the coils 47A and 47B are wound and tightened around the vibration sensing member 46, and the displacement detection parts 14, 15. By driving the coils 47A and 47B based on the detection result S obtained from 17.18.19, the displacement of the vibration sensing member 46 that is integrally configured with the coils 47A and 47B is suppressed and braked as a result. do.

[Effect]

A magnetic circuit is constructed using the vibration sensing member 46, and coils 47A and 47B are wound around the vibration sensing member 46 to form the suppressor 2.
．． By configuring 41, 42, 43, 45, 47A and 47B, the overall configuration can be simplified, space can be used effectively, and the combined configuration can be made smaller accordingly.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

[1] First Embodiment In FIG. 1, in which parts corresponding to those in FIG. In addition to the magnet 43, a vibration sensing member 46 constitutes a magnetic circuit.

That is, the permanent magnet 43 has a cylindrical shape with both end surfaces magnetized to N and S poles, respectively, and cylindrical magnetic yokes 41 and 42 extend inwardly with respect to the permanent magnet 43. It is fixed to the casing 45 by being sandwiched between them.

On the other hand, the vibration sensing member 46 has a cylindrical shape made of a magnetic material, is held movably in the X direction defined by the cylindrical axis direction by the plate spring 12, and is connected between its outer peripheral side surface and the magnetic yokes 41 and 42. A gap is formed between the inner peripheral side surface and the inner circumferential side surface.

Therefore, N-pole and S-pole magnetic poles are formed on the inner peripheral side surfaces of the magnetic yokes 41 and 42, respectively, and the vibration sensing member 46 forms a magnetic path connecting the magnetic poles with a gap in between.

On the other hand, on the outer peripheral side surface of the vibration sensing member 46, servo coils 47A and 47B are wound and tightened in the gaps formed between the magnetic yokes 41 and 42, respectively, and the servo circuit section Servo output S obtained from 2 (Fig. 2).

The displacement of the vibration-sensing member 46 is suppressed according to the amount of vibration.

Therefore, by configuring the magnetic circuit using the vibration sensing member 46 in this way, and by winding the servo coils 47A and 47B around the outer peripheral side of the vibration sensing member 46, the vibration sensing member 46 and the casing 45 Permanent magnets 43, magnetic yokes 41 and 42, and servo coils 47A and 47B can be arranged between them, and the length of the displacement detection section 40 in the tube axis direction can be shortened accordingly. Therefore, the configuration of the entire displacement detecting section 40 can be simplified and the entire structure can be made smaller, and the amount of vibration can be detected with high accuracy, and the range of application of the displacement measuring device can be expanded. .

Furthermore, in this embodiment, the collimator lens 15 is arranged to protrude within the vibration sensing member 46.

That is, in the casing 45, a holding part 45A formed integrally with the casing 45 is provided on the back surface portion of the vibration sensing member 46, and is configured to protrude into the vibration sensing member 46 at the center position of the holding part 45A. Cylindrical protrusion 45
B.

Furthermore, a holding member 50 is provided at the root portion of the protrusion 45B.
The laser diode 14 is fixed thereto, and the collimator lens 15 is fixed to the tip of the protrusion 45B.

In this way, the laser diode 14 can be placed close to the vibration sensing member 46, and the combined length can be further shortened accordingly.

Further, in the casing 45, a mounting member 52 is fixed with an O-ring 51 in between, and a collimator lens is attached to the photodetecting element 19 fixed to the central part of the mounting member 52 via a support member 53. The emitted light beam LA2 is made incident through 15.

Further, on the optical path of the irradiation light beam LA2, semitransparent mirrors 17 and 18 are attached to the vibration sensing member 46 and the mounting member 52, respectively, so as to face each other and to be inclined at a predetermined angle from a direction orthogonal to the optical axis of the optical path. The reflected light reflected by the semi-transparent mirror 18 on the photodetecting element 19 side is transmitted to the laser diode 14.
This is to ensure that they are not returned to the country.

In the above configuration, the laser beam emitted from the laser diode 14 is incident on the semitransparent mirrors 17 and 18 via the collimator lens 15, and is incident on the photodetecting element 19.

At this time, when vibration is applied to the displacement detection section 40, the vibration sensing member 46 is displaced with respect to the casing 45, and the distance between the semitransparent mirrors 17 and 18 changes accordingly, resulting in interference light LA4.
The amount of light changes. Thus, by detecting the interference light LA4 via the photodetection element 19, the amount of displacement can be detected.

Furthermore, a servo output S is obtained from the servo circuit section 2 (FIG. 2) in accordance with the amount of displacement, and a drive current flows through the servo coils 47A and 47B in accordance with the servo output S.

As a result, a driving force is obtained to suppress the displacement,
The amount of displacement applied to the displacement detecting section 40 can be detected with high accuracy based on the servo output S.

According to the above configuration, by configuring the magnetic circuit using the vibration sensing member 46 and winding the servo coil around the outer periphery of the vibration sensing member 46, the entire length of the displacement detection section 40 can be shortened. As a result, it is possible to obtain a displacement detection section that is compact as a whole.

Furthermore, in this embodiment, by arranging the collimator lens 15 so as to protrude into the vibration sensing member 46,
Accordingly, the combined length can be shortened, and a displacement detection section that is smaller in size can be obtained.

In this way, the displacement detection section can be downsized, so
It is possible to obtain a displacement measuring device that has higher measurement accuracy and a wider range of application than conventional ones.

[2] Second Embodiment In FIG. 2, parts corresponding to those in FIG.
This is a displacement measuring device designed to detect a displacement amount of 1.

That is, in the vibration sensing member 61 and the mounting member 52, instead of the semi-transparent mirrors 17 and 18, electrodes 62 and 63 are arranged to face each other with a predetermined distance apart.

Therefore, when the vibration sensing member 61 is displaced, the distance between the electrodes 62 and 63 changes accordingly, and the capacitance between the electrodes 62 and 63 changes accordingly.

Therefore, by detecting the change in the capacitance (2) between the electrodes 62 and 63, the displacement of the vibration sensing member 61 can be detected.

Based on the detection principle, the interelectrode capacitance detection circuit 64
The capacitance between the electrodes 62 and 63 is detected, and the detection result is output to the servo circuit section 2.

Therefore, servo control force is obtained in the servo coils 47A and 47B wound around the vibration sensing member 61 based on the drive signal S output from the servo circuit section 2, and the displacement of the vibration sensing member 61 is suppressed and braked. Can be done.

According to the configuration shown in FIG. 2, even in a servo-type displacement measuring device that electrically detects displacement based on the capacitance between the electrodes 62 and 63, a servo coil is wound around the vibration sensing member. By doing so, the length of the entire displacement detecting section can be shortened and a compact displacement detecting section can be obtained as a whole.

[3] Other Embodiments Although the first embodiment describes the case in which the collimator lens protrudes into the vibration-sensitive member, the present invention is not limited to this. Even if the servo coil is arranged so that it does not protrude inward, the length of the assembly in which the servo coil is wound around the vibration sensing member can be shortened.

Alternatively, the collimator lens may be directly attached to the vibration sensing member.

Furthermore, as shown in FIG. 3, not only the collimator lens but also a semiconductor laser may be attached within the vibration sensing member 46.

Furthermore, in this case, if the semiconductor laser is placed very close to the semi-transparent mirror and the semi-transparent mirrors 17 and 18 are placed very close, the interference detection light LA4 can be obtained even if the collimator lens is omitted. This makes it possible to simplify the configuration of the separation and combination by omitting the collimator lens.

Furthermore, by arranging the semiconductor laser close to the semi-transparent mirror and omitting the collimator lens, diverging light will be incident on the semi-transparent mirror.

Therefore, even if the semi-transparent mirror is arranged vertically without tilting, the reflected light beam reflected by the semi-transparent mirror of the photodetecting element 19 can be prevented from being fed back to the laser diode 14.

Thus, there is no need to tilt the translucent mirror and place it at an angle.
Accordingly, the adjustment work can be simplified and a displacement measuring device having a simple structure as a whole can be obtained.

Furthermore, as shown in FIG. 4, the semiconductor laser, the collimator lens, and the photodetecting element may be arranged on the side of the vibration sensing member and the mounting member, respectively, contrary to the arrangement shown in FIG. 3.

Furthermore, in the above embodiment, a case was described in which a servo coil was wound in each of the two gaps formed between the vibration sensing member and the magnetic yoke. Alternatively, a servo coil may be provided only in one gap.

Further, in the above-described embodiments, a case was described in which the present invention was applied to a servo-type displacement detection device configured to detect the displacement of a vibration sensing member using an electrical method and a mechanical method. The present invention is not limited to this, and can be widely applied to servo-type displacement measuring devices that detect displacement of a vibration sensing member using other detection means.

Furthermore, in the above-mentioned embodiment, a case was described in which the present invention was applied to a displacement measuring device that measures minute vibrations.
The present invention is not limited to this, but includes temperature detection information, pressure detection information,
The present invention can be widely applied to displacement measurement devices that convert physical displacement amounts such as position detection information into displacement of a vibration sensing member and measure the displacement.

〔Effect of the invention〕

As described above, according to the present invention, a magnetic circuit is constructed using a vibration-sensing member, and a coil is wound around the vibration-sensing member, so that the structure can be simplified accordingly, and the overall structure can be simplified. A small displacement measuring device can be obtained as follows.

[Brief explanation of the drawing]

FIG. 1 is a linear sectional view showing one embodiment of a displacement measuring device according to the present invention, FIG. 2 is a linear sectional view showing a second embodiment thereof, and FIG. 3 is a linear sectional view showing a third embodiment thereof. Route cross section,
FIG. 4 is a linear sectional view showing the fourth embodiment, FIG. 5 is a linear sectional view showing a conventional displacement measuring device, and FIG. 6 is a characteristic curve diagram for explaining its operation. 1.40... Displacement detection section, 2... Servo circuit section, 13.46.61... Vibration sensing member, 1
4... Laser diode, 17.18...
...Semi-transparent mirror, 19...Photodetection element, 24.4
7A, 47B... Servo coil, 29.43.
・Pa...Permanent magnet, 3QA, 30B.

Claims (1)

[Scope of Claims] A vibration-sensing member configured to be displaced relative to a case in accordance with the amount of displacement, a displacement detection section configured to detect displacement of the vibration-sensing member, and detection by the displacement detection section A displacement measuring device comprising a suppressing section that suppresses and brakes displacement of the vibration sensing member based on the results, wherein the suppressing section includes a magnetic circuit formed by a permanent magnet fixed to the case and the vibration sensing member. , a coil wound around the vibration sensing member on a magnetic path of a magnetic circuit formed by the permanent magnet and the vibration sensing member, and a coil configured to be wound around the vibration sensing member; A displacement measuring device characterized in that displacement of the vibration-sensing member is suppressed and braked by driving the coil based on the vibration-sensing member.