JP5330620B1 - Servo type acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a servo type acceleration sensor which can be constituted by inexpensive parts and can be easily assembled and adjusted.
A pendulum unit 6 that is displaced according to acceleration, a frame unit 7 that supports the pendulum unit 6, displacement detection units 16a and 16b that detect displacement of the pendulum unit 6 by a change in capacitance, and A servo circuit unit 3 is provided for supplying a current for controlling the displacement of the pendulum unit 6 to the coil 13a provided on the pendulum unit 6 based on the amount of change in capacitance detected by the displacement detection units 16a and 16b. 3 is a servo type acceleration sensor 1 that outputs the current supplied by 3 as acceleration, and is a metal that forms flexible portions 11c and 11d that also serve as electrode wiring portions 11e and 11f of the displacement detection portions 16a and 16b and wiring portions of the coil 13a. The thin plate member 11 is sandwiched between a pair of pendulum printed boards 12a and 12b and a pair of frame printed boards 17a and 17b, and the surface of the pendulum 6 and the surface of the frame 7 are formed in the same plane.
[Selection] Figure 2

Description

  The present invention relates to a servo-type acceleration sensor used for a seismometer or the like.

  In the capacitance type servo acceleration sensor, when acceleration is applied, the pendulum part tends to displace with respect to the frame part. However, the displacement is detected by a change in the electrostatic capacity, and the coil provided in the pendulum part is electrostatically detected. An electromagnetic force is generated by flowing a current according to the change in the capacity so that the pendulum portion is apparently stationary. Since this current is proportional to the acceleration, the acceleration can be known by measuring the current.

  In Patent Document 1, a vibrator (pendulum part) is constituted by a plurality of substrates on which a coil pattern is formed, and a flexible body is provided on one end side of the vibrator (pendulum part) as a support for the vibrator (pendulum part). A servo-type vibration sensor is described in which a spring is provided and this spring also functions as a wiring material for a coil pattern.

  In Patent Document 2, a movable plate (pendulum part) and a hinge are separated, and a hinge for supporting the movable plate (pendulum part) is formed of a flexible plate (metal spring material). An inclinometer is described which is fixed to a movable plate (pendulum portion) and a fixed plate (frame portion) by a U-shaped clip member.

Japanese Patent No. 2861694 Japanese Patent No. 2913525

  In the technique described in Patent Document 1, the vibrator (pendulum unit) is controlled and driven by a magnetic force, and the driving force is proportional to the number of turns of the coil, the gap magnetic field, and the current flowing through the coil. In such a component configuration, it is difficult to secure a gap magnetic field (for example, 5000 gauss), to secure the number of turns in the coil pattern (for example, 600 turns), and to pass a considerable current, so it is difficult to put it to practical use. .

  In the technique described in Patent Document 2, the flexible plate is fixed to the fixed plate and the movable plate with a U-shaped clip member, so that the number of parts increases, the assembly work is not easy, and the size is reduced. Is unsuitable and increases the number of assembly steps.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a servo-type acceleration sensor that can be configured with inexpensive parts and can be easily assembled and adjusted. It is something to try.

  In order to solve the above problems, the invention according to claim 1 includes a pendulum part that is displaced according to acceleration, a frame part that supports the pendulum part, and a displacement detection part that detects displacement of the pendulum part by a change in capacitance. And a servo circuit unit for supplying a current for controlling the displacement of the pendulum unit to a coil provided in the pendulum unit based on the amount of change in capacitance detected by the displacement detection unit. A servo-type acceleration sensor that outputs a current to be accelerated as the pendulum part and the frame part are sandwiched between a pair of pendulum part printed boards and a pair of frame part printed boards. The surface of the pendulum part and the surface of the frame part are configured to be in the same plane, the pendulum part is supported by the frame part via the metal thin plate member, and the electrode wiring of the displacement detection unit is connected to the metal thin plate member And coil wiring And it forms a flexible portion which also serves.

  The displacement detection unit includes electrodes formed on the pair of pendulum printed circuit boards, and housings facing the electrodes. At least one of the housings forms a magnetic circuit, and the frame unit. And the gap between the electrodes of the displacement detector can be set by the thickness of each spacer sandwiched between the housings.

  A convex part is formed on the tip end side of the pendulum part, a notch part facing the convex part is formed in the frame part, and the metal thin plate members constituting the convex part and the notch part are respectively the pendulum part. It can project from the printed circuit board for a frame and the printed circuit board for a frame part.

  It can be formed by bending at least a part of the electrode wiring part.

  A plurality of minute holes can be formed on a surface of the metal thin plate member sandwiched between the pendulum printed board and the frame printed board.

  According to the present invention, the pendulum part and the frame part are configured by sandwiching the metal thin plate member between the pair of pendulum part printed circuit boards and the pair of frame part printed circuit boards, so that the assembly operation of the pendulum part and the frame part is easy. At the same time, it can be configured with inexpensive parts.

  Further, if the gap between the electrodes of the displacement detection unit is set by the thickness of the spacer, the gap adjustment between the electrodes becomes easy.

  If a convex part is formed on the tip side of the pendulum part and a notch part where the convex part faces is formed in the frame part, the positional deviation of the pendulum part with respect to the frame part can be easily confirmed.

  If at least a part of the electrode wiring part is bent, the pendulum part can be prevented from being biased by releasing stress due to assembly or pulling.

  Also, if a plurality of minute holes are formed on the surface of the metal thin plate member sandwiched between the pendulum printed board and the frame printed board, an adhesive is applied to form a pair of pendulum printed boards and a pair of frame parts. When the printed circuit board is bonded and brought into close contact, the adhesive enters the micropore and cures as it is, so that a sufficient adhesive force can be obtained (anchor effect).

Schematic sectional view of a servo acceleration sensor according to the present invention Schematic cross section of sensor Plan view of sheet metal member Plan view of printed circuit board for pendulum Plan view of printed circuit board for frame Plan view of printed circuit board for pendulum and frame printed with adhesive It is explanatory drawing of a 1st assembly jig, (a) is a top view of a 1st assembly jig, (b) is a side view of a 1st assembly jig, (c) is a print for pendulum parts on a 1st assembly jig Plan view of the board and frame printed circuit board placed Plan view of a state in which a thin metal plate member is placed on the pendulum printed board and the frame printed board Plan view with the pendulum printed circuit board and the frame printed circuit board placed on a thin metal plate It is explanatory drawing of a 2nd assembly jig, (a) is a top view of a 2nd assembly jig, (b) is a side view of a 2nd assembly jig, (c) is a 1st assembly jig of a 2nd assembly jig. The top view of the state set to the implement, (d) is the side view of the state which set the 2nd assembly jig to the 1st assembly jig Top view of pendulum and frame Enlarged view of the tip convex part of the pendulum part and the cutout part of the frame part Cross-sectional view of the pendulum with the coil attached It is explanatory drawing of a 1st housing, (a) is a top view, (b) is sectional drawing. It is explanatory drawing of a 2nd housing, (a) is a top view, (b) is sectional drawing. Top view of spacer It is explanatory drawing of a base member, (a) is a top view, (b) is sectional drawing.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the servo acceleration sensor 1 according to the present invention includes a sensor unit 2, a servo circuit unit 3, a case 4, and a base member 5. The sensor unit 2 is attached to the base member 5, and the servo circuit unit 3 is attached to the sensor unit 2.

  As shown in FIG. 2, the sensor unit 2 includes a pendulum unit 6, a frame unit 7, a first housing 8, a second housing 9, two spacers 10a and 10b, and the like. The sensor portion 2 has a substantially cylindrical shape, a height of about 15 mm, and an outer diameter of about 23 mm.

  The pendulum part 6 and the frame part 7 are formed by sandwiching and bonding the metal thin plate member 11 between the pair of pendulum part printed boards 12a and 12b and the frame part printed boards 17a and 17b. Coils 13a and 13b are attached to the printed circuit boards 12a and 12b.

  The electrodes 14a, 14b provided on the printed circuit boards 12a, 12b for the pendulum part are arranged on both sides in the vicinity of the end part opposite to the side supported by the frame part 7 through the metal thin plate member 11 of the pendulum part 6, Displacement detectors 16a and 16b for detecting capacitance are formed by the surface 15a of the first housing 8 and the surface 15b of the second housing 9 facing the electrodes 14a and 14b.

  Further, the frame portion 7 is sandwiched between the first housing 8 and the second housing 9 via the spacers 10a and 10b.

  As shown in FIG. 3, the metal thin plate member 11 is formed with a pendulum side portion 11a to be the pendulum portion 6 and a frame portion side portion 11b to be the frame portion 7 and also serves as wiring of the coils 13a and 13b. Electrode wiring portions 11e and 11f that form wirings of the flexible portions 11c and 11d and the electrodes 14a and 14b of the displacement detection portions 16a and 16b are formed.

  The flexible portions 11c and 11d also serving as wiring and the electrode wiring portions 11e and 11f are wired to the servo circuit portion 3. The metal thin plate member 11 is formed with two (four in total) guide holes 11g in each of the pendulum part side part 11a and the frame part side part 11b. In the case of the shape as shown in FIG. 3, unnecessary portions 11h and 11i of the thin metal plate member 11 are cut in the assembling work.

  The flexibility of the flexible portions 11c and 11d can be easily adjusted by adjusting the plate thickness of the thin metal plate member 11 and the width of the flexible portions 11c and 11d, and the variation in quality is reduced. In addition, the electrode wiring portions 11e and 11f of the electrodes 14a and 14b of the displacement detectors 16a and 16b are bent into, for example, a substantially U-shape so that stress applied during assembly is released. This can be prevented.

  As shown in FIG. 4, two guide holes 12c and through holes 12d are formed in the pendulum printed circuit boards 12a and 12b. The pendulum printed boards 12a and 12b are provided with bow-shaped electrodes 14a and 14b and three coil positioning copper foil patterns 14c. Note that the electrodes 14a and 14b and the copper foil pattern 14c are not present on the adhesion surface (back surface) of the pendulum printed circuit boards 12a and 12b to the pendulum side portion 11a of the metal thin plate member 11.

  As shown in FIG. 5, two guide holes 17c are formed in the frame printed boards 17a and 17b. Further, the surface (front surface) of the frame printed circuit boards 17a and 17b in contact with the spacers 10a and 10b is the same thickness as the electrodes 14a and 14b of the pendulum printed circuit boards 12a and 12b, and is covered with copper foil. A pattern 17d is formed. In addition, the copper foil pattern 17d does not exist in the adhesive surface (back surface) with the frame part side site | part 11b of the metal thin plate member 11 of the printed circuit boards 17a and 17b for frames.

  Next, the assembly work procedure of the servo acceleration sensor 1 according to the present invention will be described. First, in order to assemble the pendulum part 6 and the frame part 7 constituting the sensor part 2, as shown in FIG. 6, an adhesive 18 is applied to a predetermined portion on the back surface of the pendulum part printed boards 12a and 12b. Similarly, the adhesive 18 is applied to a predetermined portion on the back surface of the frame portion printed boards 17a and 17b. As the adhesive 18, a heat curing type epoxy adhesive is suitable.

  Next, as shown in FIGS. 7A and 7B, a first assembly jig 20 provided with a screw hole 20a and four guide pins 20b is prepared. Then, as shown in FIG. 7C, the guide hole 12c and the frame portion of the pendulum printed board 12a are placed on the first assembly jig 20 with the surface (back surface) coated with the adhesive 18 facing upward. The guide holes 17c of the printed circuit board 17a are respectively inserted into the guide pins 20b, and the one printed circuit board 12a for the pendulum part and the printed circuit board 17a for the frame part are placed.

  Next, as shown in FIG. 8, the metal thin plate member 11 is placed on the pendulum printed board 12 a and the frame printed board 17 a placed on the first assembly jig 20 with the adhesive application surface facing upward. 11i is cut, and the thin metal plate member 11 is placed by inserting two guide holes 11g into the guide pins 20b of the first assembly jig 20 respectively. In addition, the metal thin plate member 11 shown in FIG. 8 is in a state before cutting the unnecessary portion 11h.

  Next, as shown in FIG. 9, the guide hole 12c of each printed circuit board 12b, 17b with the adhesive-coated surface (back surface) of the other printed circuit board 12b for pendulum and the printed circuit board 17b for the other frame section facing down. , 17 c are inserted into the guide pins 20 b of the first assembly jig 20 and placed on the thin metal plate member 11.

  Next, as shown in FIGS. 10A and 10B, a second assembly jig 21 provided with a through hole 21a and four loose fitting holes 21b, and a fastening bolt 22 are prepared. The loose fitting holes 21b are for preventing the second assembly jig 21 from hitting the guide pins 20b of the first assembly jig 20 when the second assembly jig 21 is placed. Then, the second assembly jig 21 is placed on the pendulum printed circuit board 12b and the frame printed circuit board 17b. The screw holes 20a and the through holes 21a, the guide pins 20b, and the loose fitting holes 21b of the first assembly jig 20 are formed. Place it in position.

  Further, as shown in FIGS. 10 (c) and 10 (d), the tightening bolt 22 is connected to the through hole 21 a of the second assembly jig 21, the through hole 12 d of the pendulum printed board 12 b, and the center of the thin metal plate member 11. Are inserted into the through holes 12d of the printed circuit board 12a for the pendulum and the pendulum, screwed into the screw holes 20a of the first assembly jig 20, and tightened with a predetermined torque. Here, the tightening bolt 22 is used, but instead of tightening with the tightening bolt 22, a constant load may be applied using the second assembly jig 21 as a weight.

  Thus, the pair of pendulum printed boards 12a and 12b and the pair of frame printed boards 17a coated with the metal thin plate member 11 and the adhesive 18 by the first assembly jig 20 and the second assembly jig 21, respectively. Heat curing is performed under predetermined conditions with 17b sandwiched at a predetermined pressure.

  Further, if a plurality of unillustrated micro holes (square holes □ 0.2 mm) are formed on the entire bonding surface of the metal thin plate member 11, the pendulum printed circuit boards 12a and 12b and the frame portion coated with the adhesive 18 are used. When the printed circuit boards 17a and 17b are bonded to the metal thin plate member 11 by fastening with the first assembly jig 20, the second assembly jig 21 and the fastening bolts 22, the adhesive 18 enters the microholes and heat cures as it is. Therefore, it is possible to obtain a sufficient adhesive force (anchor effect) while preventing the adhesive 18 from protruding or warping due to adhesion.

  If the pendulum printed circuit boards 12a and 12b and the frame printed circuit boards 17a and 17b are glass epoxy substrates, the pendulum printed circuit boards 12a and 12b and the frame printed circuit board 17a are used without using the adhesive 18. 17b may be heat-sealed to the thin metal plate member 11.

  By assembling as described above, even when the pendulum printed boards 12a and 12b and the frame printed boards 17a and 17b are slightly warped, the flatness of the pendulum 6 and the frame 7 is improved by heating during curing. , Almost the same plane can be obtained. Further, the pendulum portion 6 is supported by the frame portion 7 via the flexible portions 11 c and 11 d of the metal thin plate member 11, and has an integrated structure with good symmetry with respect to the metal thin plate member 11.

  Next, as shown in FIG. 11, after the adhesive 18 is cured, the pendulum portion 6 and the frame portion 7 are removed from the assembly jigs 20 and 21, and an unnecessary portion 11 h of the metal thin plate member 11 is cut off.

  By the assembling work according to the above procedure, the pendulum part 6 and the frame part 7 have an integral structure. And as shown in FIG. 12, while forming the convex part 6a in the front end side of the pendulum part 6, the notch part 7a is formed in the frame part 7 which this convex part 6a faces, and the convex part 6a and the notch part 7a are formed. The pendulum side part 11a and the frame part side part 11b of the metal thin plate member 11 forming the pendulum part 6 and the frame part 7 are protruded from the pendulum part printed boards 12a and 12b and the frame part printed boards 17a and 17b, respectively. It becomes easy to confirm the positional deviation in the displacement direction.

  Next, as shown in FIG. 13, the coils 13a and 13b are placed in accordance with the coil positioning copper foil patterns 14c of the pendulum printed boards 12a and 12b on both sides of the pendulum 6, and are adhered with an adhesive. In order to maintain the balance, the coils 13 a and 13 b are attached to both surfaces of the pendulum unit 6. Then, only the coil 13a on one side is electrically connected to the flexible portions 11c and 11d that also serve as wiring. In addition, it can also be set as the structure which uses the coils 13a and 13b of both surfaces.

  By forming the copper foil pattern 14c for positioning on the printed circuit boards 12a and 12b for the pendulum part, the copper foil pattern 14c becomes a convex state (about 75 μm projecting) as compared with the printed circuit board 12a and 12b surface. 13b can be easily positioned.

  Next, as shown in FIG. 14, the first housing 8 constituting the magnetic circuit is formed. As the material of the first housing 8, a soft magnetic material (for example, electromagnetic soft iron) having a high saturation magnetic flux density is used. A magnet (for example, a rare earth magnet) 25 is provided at the center. The first housing 8 is provided so as to surround the coil 13a, and applies a predetermined magnetic field to the gap where the coil 13a is located. 8a is a screw hole for coupling with the second housing 9, and 8b is a guide hole.

  Further, as shown in FIG. 15, the second housing 9 is formed. The second housing 9 does not constitute a magnetic circuit, but may be configured similarly to the first housing 8 if the coil 13b is also used. The same material as that of the first housing 8 is used in order to achieve a thermal balance. 9a is a hole for coupling with the first housing 8, and 9b is a guide hole.

  Next, the frame portion 7 in which the thin metal plate member 11 is sandwiched and bonded by the pair of frame printed boards 17a and 17b is used to guide the two spacers 10a and 10b using guide pins (not shown) and coupling bolts (not shown). The first housing 8 and the second housing 9 are interposed therebetween. The spacers 10a and 10b are made of thin and non-magnetic metal materials. As shown in FIG. 16, the spacers 10a and 10b have substantially the same shape as the frame printed boards 17a and 17b, but are formed without cutouts. 10c is a coupling hole and 10d is a guide hole.

  The thickness of the spacer 10a is obtained so that a desired capacitance can be obtained in the displacement detector 16a formed by the electrode 14a provided on one surface of the pendulum 6 and the surface 15a of the second housing 8 facing the electrode 14a. Thus, the electrostatic capacity is adjusted. Similarly, in the displacement detection unit 16b constituted by the electrode 14b provided on the other surface of the pendulum unit 6 and the surface 15b of the second housing 9, the capacitance varies depending on the thickness of the spacer 10b so that a desired capacitance can be obtained. Is adjusted. The spacers 10a and 10b have the same thickness, but may have different thicknesses as necessary.

  As described above, the use of the spacers 10a and 10b facilitates adjustment for obtaining a desired capacitance. In the displacement detectors 16a and 16b, the surfaces 15a15b of the housings 8 and 9 are grounded.

  Next, the servo circuit unit 3 is attached to the second housing 9. The coil 13a is connected to the servo circuit unit 3 through flexible portions 11c and 11d that also serve as wiring of the thin metal plate member 11. The electrodes 14a and 14b of the displacement detectors 16a and 16b are connected to the servo circuit unit 3 via the electrode wiring units 11e and 11f.

  Next, the sensor part 2 to which the servo circuit part 3 is attached is fixed to the base member 5 shown in FIG. At this time, by using the three angle adjusting screw holes 5b provided in the base member 5, a slight shift of the sensitive shaft generated during assembly can be performed by adjusting the screw advance / retreat adjustment angle of the sensor unit 2 with respect to the base member 5. Therefore, the position of the pendulum unit 6 can be corrected.

  Next, the case 4 is fixed to the base member 5 to which the sensor unit 2 is fixed at four points with screws using the coupling holes 5c. Although the outer shape of the case 4 is a substantially rectangular parallelepiped shape, it may be a cylindrical shape. By using aluminum as the material, it is possible to reduce the weight and reduce the cost while reducing the generation of noise and the influence of noise by the shielding effect. If it is a magnetic material, the influence of magnetic noise can be reduced. Engineering plastics may be used as long as they do not deform under the conditions of use and are stable with respect to temperature. It may be selected as desired.

  Since the pendulum part 6 and the frame part 7 are sandwiched and clamped between the first assembly jig 20 and the second assembly jig 21 as in the assembly work according to the above procedure, or the adhesive 18 is heated and cured, The pendulum part 6 and the frame part 7 are almost on the same plane, and the required capacitance can be easily set by sandwiching spacers 10a and 10b having a predetermined thickness between the frame part 7 and the housings 8 and 9, respectively. Can do.

  Moreover, even if it is the structure which used the printed circuit boards 12a, 12b, 17a, 17b for the pendulum part 6 and the frame part 7, since the heat resistance of -50 degreeC-100 degreeC can be obtained, it is in the required specification of a seismometer. A sufficient temperature range can be obtained.

  According to the present invention, it is possible to provide a servo-type acceleration sensor that is an inexpensive component and can be easily assembled and adjusted.

  DESCRIPTION OF SYMBOLS 1 ... Servo type acceleration sensor, 2 ... Sensor part, 3 ... Servo circuit part, 4 ... Case, 5 ... Base member, 6 ... Pendulum part, 6a ... Convex part, 7 ... Frame part, 7a ... Notch part, 8 ... 1st housing, 9 ... 2nd housing, 10a, 10b ... Spacer, 11 ... Metal thin plate member, 11a ... Pendulum side part, 11b ... Frame part side part, 11c, 11d ... Flexible part, 11e, 11f ... Electrode wiring part 11g, 12c, 17c ... guide holes, 12d, 21a ... through holes, 12a, 12b ... pendulum printed circuit boards, 13a, 13b ... coils, 14a, 14b ... electrodes, 15a, 15b ... surface, 16a, 16b ... displacement Detection part, 17a, 17b ... Printed circuit board for frame part, 18 ... Adhesive, 20 ... First assembly jig, 20a ... Screw hole, 20b ... Guide pin, 21 ... Second assembly jig, 21b ... Guide hole, 22 ... Tightening bolt .

Claims (5)

A pendulum part that is displaced according to acceleration, a frame part that supports the pendulum part, a displacement detection part that detects displacement of the pendulum part by a change in capacitance, and a change in capacitance detected by the displacement detection part A servo-type acceleration sensor that includes a servo circuit unit that supplies a current for controlling the displacement of the pendulum unit to a coil provided in the pendulum unit, and outputs the current supplied by the servo circuit unit as an acceleration, The pendulum part and the frame part are formed by sandwiching a thin metal plate member between a pair of pendulum printed boards and a pair of frame printed boards, and the surface of the pendulum part and the surface of the frame part are flush with each other The pendulum part is supported by the frame part via the metal thin plate member, and a flexible part that serves as both the electrode wiring part of the displacement detection part and the coil wiring part is formed on the metal thin plate member. It is characterized by Bo type acceleration sensor. 2. The servo acceleration sensor according to claim 1, wherein the displacement detection unit includes electrodes respectively formed on the pair of pendulum printed circuit boards and housings facing the electrodes. A servo-type acceleration sensor, wherein at least one of them constitutes a magnetic circuit, and a gap between the electrodes of the displacement detector is set by a thickness of each spacer sandwiched between the frame and each housing. . 3. The servo acceleration sensor according to claim 1, wherein a convex portion is formed on a tip side of the pendulum portion, and a notch portion facing the convex portion is formed in the frame portion, and the convex portion and the The servo-type acceleration sensor according to claim 1, wherein the thin metal plate member constituting the notch portion protrudes from the pendulum printed board and the frame printed board. 4. The servo acceleration sensor according to claim 1, wherein at least a part of the electrode wiring portion is bent. 5. 5. The servo acceleration sensor according to claim 1, wherein a plurality of minute holes are formed on a surface of the metal thin plate member sandwiched between the pendulum printed circuit board and the frame printed circuit board. Servo-type acceleration sensor characterized by that.

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