WO1996019733A1 - Acceleration sensor - Google Patents

Acceleration sensor Download PDF

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Publication number
WO1996019733A1
WO1996019733A1 PCT/JP1995/002556 JP9502556W WO9619733A1 WO 1996019733 A1 WO1996019733 A1 WO 1996019733A1 JP 9502556 W JP9502556 W JP 9502556W WO 9619733 A1 WO9619733 A1 WO 9619733A1
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WO
WIPO (PCT)
Prior art keywords
acceleration
planar coil
coil
acceleration sensor
sensor according
Prior art date
Application number
PCT/JP1995/002556
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French (fr)
Japanese (ja)
Inventor
Norihiro Asada
Original Assignee
The Nippon Signal Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Nippon Signal Co., Ltd. filed Critical The Nippon Signal Co., Ltd.
Priority to US08/693,282 priority Critical patent/US5763783A/en
Priority to PCT/JP1995/002556 priority patent/WO1996019733A1/en
Priority to EP95940428A priority patent/EP0745858B1/en
Priority to DE69525935T priority patent/DE69525935T2/en
Publication of WO1996019733A1 publication Critical patent/WO1996019733A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/18—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration in two or more dimensions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/11—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by inductive pick-up

Definitions

  • the present invention relates to an acceleration sensor, and more particularly to an acceleration sensor that is highly accurate, easily manufactured at low cost, and easily reduced in size and thickness. (Background technology)
  • acceleration sensor in which a semiconductor substrate is processed by a micromachining technology to reduce the size and thickness.
  • Various types of acceleration sensors of this type such as a capacitance type, a piezoresistive type, and an induced current type, have been proposed.
  • a V-shaped groove is formed in a substrate, and a cantilever beam supported at one end side is arranged in the V-shaped groove.
  • the electrodes are arranged to face each other.
  • This displacement is detected as a change ⁇ C in the capacitance C between the two electrodes, and the acceleration is detected.
  • the beam described in the above publication has a cantilever structure, the beam can move in two directions, up and down, and laterally, and the axial sensitivity to acceleration is two axes. May be displaced laterally. In this case, it is necessary to remove the output change due to the displacement in the left and right direction, and a supplementary circuit for this is necessary, which complicates the circuit configuration. Furthermore, when the displacement amount is large, the non-support side end portion of the beam has a larger displacement amount than the support side end portion, and the distance between the electrodes may not be uniform. There is.
  • the detection sensitivity can be increased by increasing the change amount C of the capacitance C, and the change amount AC is increased.
  • the practical gap d between the electrodes is 2-3. ⁇ m is extremely narrow, and the yield is extremely poor due to dust adhering to the gap between electrodes during the manufacturing process.
  • the practical gap between electrodes is small, and the dynamic range of the sensor is small.
  • there are problems such as difficulty in producing narrow gaps uniformly. Further, there is a problem in that once the electrodes are attracted to each other, the attracting force due to the electrostatic attraction becomes strong and cannot be used.
  • a movable electrode is provided between two fixed electrodes, the movable electrode is displaced by acceleration, and a voltage corresponding to the capacitance difference due to the displacement of the movable electrode is fed back to the electrode section. Then, the movable electrode is controlled so that the capacitance difference becomes zero, and the voltage at this time is taken out as an acceleration detection signal.
  • the mass part at the center of the silicon substrate is supported by four beams extending at right angles to each other, and a piezoresistive element is provided at the root of each beam, and the piezoresistive element forms a prism circuit.
  • induction current type acceleration sensor for example, there is one described in Japanese Patent Application Laid-Open No. 5-122466.
  • a mass is provided by elastically supporting four beams at the center of the frame-shaped frame, a permanent magnet is provided on the top of the mass, while covers are provided above and below the frame, and an inner surface of the upper cover is provided. And a coil for detecting a change in the magnetic field facing the permanent magnet.
  • the induced current of the detection coil is generated only by a change in the magnetic flux. Therefore, the induced current of the detection coil is generated only when the permanent magnet is moving, that is, when the mass is displaced. Therefore, it is impossible to detect acceleration when the acceleration is constant and the mass does not move. What is detected by this acceleration sensor is a change in acceleration. To detect the acceleration itself, a circuit or the like that integrates a detection signal is required, and there is a problem that the circuit becomes complicated.
  • the present invention has been made in view of the above circumstances, and has a configuration in which acceleration is detected using magnetic coupling, whereby a dynamic range is widened, high sensitivity is obtained, and a circuit configuration is simplified. It is an object of the present invention to provide an acceleration sensor that is extremely inexpensive to manufacture and that can be easily reduced in size and thickness.
  • the periphery is supported by the frame through the frame-shaped frame and the support beam having the elastic restoring force, and the acceleration is accelerated.
  • the sensor is configured to apply an AC signal to the first planar coil.
  • the electric signal corresponding to the change in the gap between the first planar coil and the second planar coil is taken out from the second planar coil.
  • a transformer is formed by the first and second planar coils, and a displacement corresponding to the acceleration of the mass portion is detected using magnetic coupling.
  • the gap between the two planar coils can be made much larger, and when a semiconductor substrate is used, there is no influence of dust adherence and the production yield is improved, and the production cost can be reduced.
  • the sensitivity can be adjusted by changing the number of turns of the coil, high sensitivity can be achieved despite the large dynamic range.
  • the mass section is supported by the frame at four positions on the central axis orthogonal to each other, the displacement direction of the mass section can be reliably restricted to one axis, and multi-axis sensitivity can be obtained. Separation of output in case of structure can be eliminated.
  • the sensor section by processing a semiconductor substrate by a micromachining technique, miniaturization and thinning can be easily achieved.
  • it is configured to include an oscillator for applying an AC signal to the first planar coil of the sensor section, and an electronic circuit for calculating acceleration based on an electric signal output from the second planar coil.
  • a rectifier circuit configured to rectify the alternating electric signal output from the second planar coil; an analog-to-digital converter configured to convert a rectified output of the rectifier circuit into a digital signal; A rectifier circuit configured to calculate acceleration based on a digital output of the analog-to-digital converter.
  • acceleration can be detected in two axial directions.
  • the present invention is applied to a navigation system including a gyro, a position detection system of a self-propelled robot, and the like. It is possible.
  • the senor section is configured to include a magnetic body provided in proximity to the first planar coil and the second planar coil, respectively, the inductance of each coil is improved and the coupling between both coils is tight. And the sensitivity is improved.
  • FIG. 1 is a configuration diagram of a sensor unit showing an embodiment of the acceleration sensor of the present invention.
  • FIG. 2 is a sectional view taken along the line AA of FIG.
  • FIG. 3 is an exploded view of the sensor section.
  • FIG. 4 is a circuit configuration diagram of the acceleration sensor.
  • Fig. 5 is a graph showing an example of the relationship between the coupling coefficient and the gear between the coils.
  • FIG. 6 is a configuration example in the case of detecting acceleration in two directions.
  • FIG. 7 shows an example of a configuration for detecting acceleration in three directions.
  • FIG. 8 is a configuration diagram of another embodiment related to the sensor section of the acceleration sensor of the present invention.
  • FIG. 9 is a circuit diagram used for a measurement experiment of the sensor unit in FIG. Fig. 10 shows the output-acceleration of the acceleration sensor using the sensor unit of Fig. 8. It is a graph which shows a characteristic.
  • FIGS. 1 to 3 show the configuration of the sensor unit.
  • the sensor unit 1 has a mass unit 3 disposed in a frame 2 having a frame shape.
  • the mass part 3 is supported by the frame 2 via four support beams 4 at four positions on a central axis orthogonal to each other, that is, substantially at the center of each side of the mass part 3.
  • the support beam 4 is formed to be thinner than the frame 2 and the mass portion 3 and has an elastic restoring force. Therefore, the mass unit 3 is configured to be displaceable in response to the acceleration only in one axial direction of the upper and lower directions.
  • a thin-film first planar coil 5 is provided on the upper surface of the mass unit 3, and is disposed on the upper surface of a flat base 7 facing the frame 1 with a frame-shaped spacer 6 interposed therebetween.
  • a thin-film second planar coil 8 is provided so as to face the first planar coil 5.
  • the first planar coil 5 is a primary coil
  • the second planar coil 8 is a secondary coil
  • the coils 5 and 8 constitute a transformer. For example, if each thickness of the frame 2 and the spacer 6 is 200 ⁇ m, a transformer having a gap d between the coils of 400 zm is formed.
  • the frame 2, the support beam 4 and the mass 3 are formed integrally by processing a silicon substrate using micromanaging technology.
  • the spacer 6 and the base 7 are also formed by processing a silicon substrate in the same manner, and as shown in FIG. 3, these are separately processed and formed, and are superimposed on each other to form the sensor section 1. Make up.
  • FIG. 4 shows a circuit configuration of the acceleration sensor of this embodiment.
  • an oscillator 9 is connected to the first planar coil 5 of the sensor section 1, and an AC voltage is applied through a resistor.
  • the second planar coil 8 serving as a secondary coil has a rectifier circuit, for example, two diodes.
  • Rectified output of Ana port grayed from voltage doubler rectifier circuit 10 is connected voltage doubler rectifier circuit 10 composed of C 2 and a resistor R to an analog one Digital converter (hereinafter referred to as A / D converter) 11 Converted to a digital signal by 1 and input to micro computer 12.
  • the mass unit 3 When the vertical acceleration in FIG. 1 acts on the sensor unit 1, the mass unit 3 is displaced in the direction opposite to the acceleration direction, and the gear between the first plane coil 5 and the second plane coil 8 is displaced. And the coupling coefficient of the transformer formed by the first planar coil 5 (—secondary coil) and the second planar coil 8 (secondary coil) changes, and the second planar coil 8 The output voltage from changes.
  • V 0 ⁇ ⁇ k ⁇ V in
  • k is the coupling coefficient of the transformer
  • ⁇ is the frequency of the input voltage.
  • the coupling coefficient k and the output voltage V Is proportional to the, if constant ⁇ and V in, the output voltage of the secondary coil V.
  • the coupling coefficient k can be obtained.
  • This coupling coefficient k corresponds to the gap d between the first plane coil 5 and the second plane coil 8 due to the displacement of the mass section 3, and as a characteristic of the sensor section 1, If the relationship between the coefficient k and the gap d is determined, the detected output voltage V is obtained.
  • the gap d between the coils 5 and 8, that is, the amount of displacement of the mass section 3 can be known from the coupling coefficient k obtained from, and the acceleration can be detected.
  • Fig. 5 shows an example of the relationship between the gap d between both coils and the coupling coefficient k. Therefore, if the microcomputer 12 preliminarily stores a map showing the relationship between the coupling coefficient k and the gap d between the coils, the output voltage V from the second planar coil 8 of the sensor unit 1 is obtained. . Rectified by the voltage doubler rectifier circuit 10, converted into a digital signal by the AZD converter 11, and input to the micro computer (microcomputer) 12, which calculates the coupling coefficient k in the micro computer 12.
  • the gap d between the coils can be obtained from a map indicating the relationship between the coupling coefficient k and the gear d between the coils, which is stored in advance, and the displacement of the mass section 3 can be detected, and the acceleration can be obtained. Can be detected.
  • This output change of 200 mV is a large value that can be easily detected, and can take out a large change compared to the capacitance type ⁇ piezoresistive type acceleration sensor, enabling highly sensitive acceleration detection. is there.
  • the gap d between the two coils 5 and 8 is much larger than the capacitance type of 2 m to 3 m, several hundred meters, and the dynamic range can be increased. There is no influence of the adhesion of dust between the part 3 and the base 7, and the production is easy, the yield is improved, and the production cost can be reduced.
  • the processing circuit for processing the output signal from the sensor unit 1 can have a simple configuration.
  • the winding interval can be created with higher precision than in the case of manually wound or machine wound coils, and the ideal It is possible to form a transformer that obtains a value close to the ideal value according to the calculation formula of the mutual inductance and self-inductance of Detection accuracy can be improved.
  • the voltage doubler rectifier circuit 10 in the rectifier circuit for rectifying the output of the sensor section 1 the output voltage can be increased, the resolution can be increased, and the detection sensitivity can be improved.
  • one sensor unit 1 can be used as one to detect acceleration in one direction.
  • the sensor units 1 are respectively arranged on two surfaces orthogonal to each other. In this way, it is possible to detect acceleration in two directions, that is, in two dimensions.
  • FIG. 7 by arranging the sensor units 1 on three surfaces orthogonal to each other, three-dimensional acceleration can be detected. it can.
  • FIG. 7 if the configuration is such that three-dimensional acceleration can be detected, it can be applied to a navigation system for automobiles or the like and a position detection system for self-propelled robots.
  • the one-dimensional acceleration detection structure can be applied to active suspension for automobiles and the like.
  • FIG. 8 c shows another embodiment of a sensor portion of the acceleration sensor of the present invention, mounting a magnetic sensor section shown in FIG. 1 in order to improve the sensitivity of the acceleration sensor This is an example in the case of performing.
  • the sensor section 20 of the present embodiment has a thin-film first planar coil 5 provided in a frame of a frame 2 through four support beams 4 having elastic restoring force.
  • the mass part 3 is disposed, and a base 7 having a second planar coil 8 is provided at a predetermined interval from the mass part 3 via a frame-shaped spacer 6. This is the same as sensor unit 1 in Fig. 1.
  • plate-shaped first and second magnetic bodies 21 and 22 are mounted on the upper surface side of the mass unit 3 and the bottom surface side of the base 7, respectively.
  • the first magnetic body 21 is formed in a plate shape having substantially the same size as the mass part 3 and is mounted so as to cover the upper surface of the mass part 3. Therefore, the first magnetic body 21 can be displaced integrally with the mass section 3 in response to the acceleration, and becomes a part of the mass section 3.
  • the second magnetic body 22 includes a base 7 on which the second planar coil 8 is provided. It is formed in a plate shape approximately the same size as that of the base 7 and is mounted on the bottom side of the base 7.
  • the first and second magnetic bodies 21 and 22 are made of, for example, Mn-Zn ferrite material.
  • the first and second magnetic bodies 21 and 22 function as an iron core of a transformer including the first and second planar coils 5 and 8, and the first and second magnetic bodies
  • the inductance of the planar coils 5 and 8 is improved, so that the magnetic flux density generated when a current flows through the first planar coil 5 increases.
  • the magnetic flux linked to the second planar coil 8 also increases, so that the coupling between the coils becomes denser than that of the air core without a magnetic material shown in FIG. Therefore, the amount of change due to the distance between the first and second coils 5 and 8 also increases, and the sensitivity of the acceleration sensor improves.
  • a method of improving the sensitivity of the acceleration sensor using the transformer coupling of the present invention a method of increasing the amplitude of an alternating current applied to the primary coil, a method of increasing a distance between the primary coil and the secondary coil, and the like. For example, a method of narrowing the width can be considered.
  • the moving distance of the mass part becomes shorter, and the measuring range becomes narrower.
  • dust exists between the primary coil and the secondary coil, the movement of the mass is restricted by the dust, and there is a high possibility that an error will occur.
  • the first plane coil 5 is connected to the AC power supply 23.
  • a circuit in which two diodes D, a capacitor C and a resistor R are connected as shown in the figure is connected to the second plane coil 8 side. The measurement was carried out.
  • the output voltage V is shown for the air-core sensor unit 1 in Fig. 1. ul is about 3 mV , whereas in the case of the sensor unit 20 provided with the magnetic bodies 21 and 22 in FIG. 8, about 300 mV is obtained, and the output is about 100 times. The sensitivity is greatly improved.
  • the input impedance of the first planar coil 5 is approximately 4 ohms (1 MHz, 2 ohms of which are copper loss) when the core is air-core.
  • the input impedance of the first planar coil 5 When installed, it is approximately 45 ohms (1 MHz, of which 2 ohms is copper loss), and the input impedance of the first planar coil 5 is greatly increased compared to when it is air-core. Therefore, the current flowing through the first planar coil 5 for the same input voltage is one order of magnitude smaller than when the air core is used. Therefore, the amount of heat generated by the first planar coil 5 can be significantly reduced.
  • the magnetic flux density is increased, sufficient measurement sensitivity can be obtained without reducing the distance between the coils, and the measurement range can be expanded.
  • magnetic materials 21 and 22 are laminated on the sensor as a simple plate. If you do, the processing cost will be low. If a material such as ferrite, which is generally used, is used as the material of the magnetic material, it is inexpensive and does not cause a large cost increase as compared with an air core material.
  • FIG. 10 shows the relationship between the output voltage and the acceleration of the sensor unit 20 shown in FIG.
  • two-dimensional acceleration can be detected by arranging the sensor units 20 in FIG. 8 on two surfaces orthogonal to each other as shown in FIG. 6, and orthogonal to each other as shown in FIG. It is needless to say that three-dimensional acceleration can be detected.
  • the mass is displaced in response to the acceleration and the fixed portion is provided with a planar coil facing each other to constitute a transformer, and the coil is formed by using the magnetic coupling between the two coils. Since the gap between the mass part and the displacement of the mass part is detected, the gap between the mass part and the fixed part can be much larger than that of the conventional capacitance type, and the manufacturing is easy. It is easy, is not affected by dust adhesion between gaps, can reduce manufacturing costs, and can have a wide dynamic range. Further, since the sensitivity can be freely adjusted by adjusting the number of coil turns, high sensitivity can be achieved ( accordingly, a small and thin, high-sensitivity acceleration sensor can be provided at low cost.
  • the sensitivity can be adjusted, it is needless to say that the sensitivity can be reduced, and that the sensitivity can be manufactured according to the intended use.
  • the present invention can provide a small, thin, high-sensitivity acceleration sensor at low cost, and can improve control accuracy and reduce cost of a system using an acceleration sensor. Usability is great

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Abstract

An acceleration sensor which detects acceleration by utilizing magnetic coupling. A mass section (3) is displaceably supported by a frame (2) through supporting beams (4). A first planar coil (5) is provided on the section (5), and a second planar coil (8) is so provided as to face to the coil (5) at an interval. A transformer is constituted of the coil (5) as a primary coil and the coil (8) as a secondary coil. The sensor detects acceleration by detecting the variation of the distance between the coils (5 and 8), namely, the displacement of the mass section (3) by utilizing magnetic coupling.

Description

明 糸田 書  Akira Itoda
加 速 度 セ ン サ  Acceleration sensor
〔技術分野〕  〔Technical field〕
本発明は、 加速度センサに関して、 特に、 高精度で、 しかも、 安 い製造コス トで小型化及び薄型化の容易な加速度センサに関する。 〔背景技術〕  The present invention relates to an acceleration sensor, and more particularly to an acceleration sensor that is highly accurate, easily manufactured at low cost, and easily reduced in size and thickness. (Background technology)
従来、 マイ クロマシニング技術で半導体基板を加工して小型化及 び薄型化を図った加速度センサが知られている。 この種の加速度セ ンサと しては、 静電容量型、 圧電抵抗型及び誘導電流型等の種々の 構造のものが提案されている。  Conventionally, there has been known an acceleration sensor in which a semiconductor substrate is processed by a micromachining technology to reduce the size and thickness. Various types of acceleration sensors of this type, such as a capacitance type, a piezoresistive type, and an induced current type, have been proposed.
静電容量型としては、 例えば特開昭 5 7 — 1 2 5 3 5 5号公報に 提案されたものがある。  As the capacitance type, for example, there is one proposed in Japanese Patent Application Laid-Open No. 57-125355.
このものは、 基板に V形溝を形成し、 この V形溝内に、 一端側で 支持される片持ちビームを配置し、 互いに対面する V形溝の傾斜面 とビームの傾斜面に、 それぞれ電極を対面させて配置する構成であ る。 そして、 加速度が加わるとその大きさに応じてビームが変位す る。 この変位量を両電極間の静電容量 Cの変化 Δ C として検出し加 速度を検出するものである。  In this device, a V-shaped groove is formed in a substrate, and a cantilever beam supported at one end side is arranged in the V-shaped groove. In this configuration, the electrodes are arranged to face each other. When acceleration is applied, the beam is displaced according to the magnitude. This displacement is detected as a change ΔC in the capacitance C between the two electrodes, and the acceleration is detected.
しかし、 上記公報記載のものは、 片持ち構造であるため上下及び 横の 2方向にビームが移動可能で、 加速度に対する軸感度が 2軸と なるので、 例えば上下方向の加速度に対しても、 ビームが横方向に 変位する可能性がある。 この場合、 左右方向の変位による出力変化 分を除く必要があり、 このための補慣回路が必要で、 回路構成が複 雑となる。 更に、 変位量が大き く なるとビームの支持側端部より非 支持側端部の方が変位量が大き く なって電極間ギヤ ップの距離が均 一でなく なる可能性がある等の問題がある。  However, since the beam described in the above publication has a cantilever structure, the beam can move in two directions, up and down, and laterally, and the axial sensitivity to acceleration is two axes. May be displaced laterally. In this case, it is necessary to remove the output change due to the displacement in the left and right direction, and a supplementary circuit for this is necessary, which complicates the circuit configuration. Furthermore, when the displacement amount is large, the non-support side end portion of the beam has a larger displacement amount than the support side end portion, and the distance between the electrodes may not be uniform. There is.
また、 静電容量型の加速度センサの場合、 検出感度を高めるには 静電容量 Cの変化量厶 Cを大き くすればよ く、 この変化量 A Cを大 き くするには、 元の静電容量 Cを大き くすればよい。 静電容量 Cを 大き くするには、 電極面積を A、 電極間ギャ ップを d とすると、 静 電容量 Cは、 〇 = ε - A / d は誘電率） であり、 電極面積 Aを 大き くするか又は電極間ギャ ップ dを小さ くする方法がある。 In the case of a capacitance-type acceleration sensor, the detection sensitivity can be increased by increasing the change amount C of the capacitance C, and the change amount AC is increased. To increase the size, the original capacitance C should be increased. If the electrode area is A and the gap between the electrodes is d to increase the capacitance C, the capacitance C is 〇 = ε-A / d is the dielectric constant. There is a method of increasing the size or reducing the gap d between the electrodes.
しかし、 電極面積 Aを大き くするとセンサが大き く なり、 センサ の小型化の点からは電極間ギヤ ップ dを狭くする方がよいが、 実用 的な電極間ギャ ップ dは 2〜 3 〃 mと極めて狭く、 製造過程におい て電極間ギャ ップにゴミが付着する等により極端に歩留りが悪い。 また、 実用的な電極間ギャ ップが狭く センサのダイナミ ッ ク レ ンジ が小さい。 更に、 狭いギャ ップを均一に製作するこ とが難しい等の 問題がある。 また、 電極同士が一旦互いに吸着すると静電引力によ る吸着力は強く使用不能になるという問題がある。  However, if the electrode area A is increased, the sensor becomes larger, and it is better to reduce the gap d between the electrodes from the viewpoint of miniaturization of the sensor, but the practical gap d between the electrodes is 2-3.狭 m is extremely narrow, and the yield is extremely poor due to dust adhering to the gap between electrodes during the manufacturing process. In addition, the practical gap between electrodes is small, and the dynamic range of the sensor is small. In addition, there are problems such as difficulty in producing narrow gaps uniformly. Further, there is a problem in that once the electrodes are attracted to each other, the attracting force due to the electrostatic attraction becomes strong and cannot be used.
静電容量型の改良形として、 吸着により使用不能となるのを防止 すると共に、 ダイナミ ッ ク レンジの拡大を図った、 例えば特開平 5 - 2 6 9 0 2号公報に記載された静電サーボ型がある。  As an improvement of the capacitance type, it has prevented the use of the device by suction and expanded the dynamic range. For example, the electrostatic servo described in Japanese Patent Application Laid-Open No. 5-26902 There is a type.
このものは、 2つの固定電極間に可動電極を設け、 加速度によつ て可動電極が変位するようにし、 可動電極の変位による静電容量差 に対応した電圧を電極部にフ ィ ー ドバッ ク して静電容量差が零とな るように可動電極を制御し、 この時の電圧を加速度の検出信号とし て取り出す構成である。  In this device, a movable electrode is provided between two fixed electrodes, the movable electrode is displaced by acceleration, and a voltage corresponding to the capacitance difference due to the displacement of the movable electrode is fed back to the electrode section. Then, the movable electrode is controlled so that the capacitance difference becomes zero, and the voltage at this time is taken out as an acceleration detection signal.
しかし、 固定電極と可動電極との間を一定に保持するために電極 に印加する静電引力の電圧と検出電圧の分離が難しく、 センサ部か らの出力の処理回路も複雑になるという問題がある。  However, it is difficult to separate the voltage of the electrostatic attraction applied to the electrodes from the detection voltage in order to keep the fixed electrode and the movable electrode constant, and the circuit for processing the output from the sensor unit becomes complicated. is there.
圧電抵抗型の加速度センサとしては、 例えば特開昭 5 9 - 9 9 3 5 6号公報に記載されたものがある。  An example of a piezoresistive acceleration sensor is described in Japanese Patent Application Laid-Open No. 59-93956.
このものは、 シリ コ ン基板の中央部の質量部を、 互いに直角に延 びる 4本の梁で支持し、 各梁の根本に圧電抵抗素子を設け、 これら 圧電抵抗素子でプリ ッ ジ回路を構成して加速度に対応する出力を取 り出す構成である。 In this device, the mass part at the center of the silicon substrate is supported by four beams extending at right angles to each other, and a piezoresistive element is provided at the root of each beam, and the piezoresistive element forms a prism circuit. Configuration to obtain the output corresponding to the acceleration. It is a configuration to start.
しかし、 加速度に対する圧電抵抗素子の変化量が小さので、 検出 回路が複雑となる。 また、 半導体抵抗は温度係数が大きいので、 温 度補儻のための回路が必要となるという問題がある。  However, since the amount of change of the piezoresistive element with respect to acceleration is small, the detection circuit becomes complicated. In addition, since a semiconductor resistor has a large temperature coefficient, there is a problem that a circuit for temperature compensation is required.
誘導電流型の加速度センサとしては、 例えば特開平 5 — 1 2 2 4 6号公報に記載されたものがある。  As an induction current type acceleration sensor, for example, there is one described in Japanese Patent Application Laid-Open No. 5-122466.
このものは、 枠状のフレームの中央に 4本のビームで弾性支持し て質量部を設け、 質量部の上面に永久磁石を設ける一方、 フ レーム の上下にカバ一を設け、 上側カバーの内面に、 前記永久磁石と対向 させて磁界の変化を検出するコイルを設ける構成である。 そして、 加速度により質量部が変位した時に、 検出コイルを通過する永久磁 石の磁束が変化して検出コイルに誘導電流が流れる。 この誘導電流 の変化から加速度を検出する。  In this type, a mass is provided by elastically supporting four beams at the center of the frame-shaped frame, a permanent magnet is provided on the top of the mass, while covers are provided above and below the frame, and an inner surface of the upper cover is provided. And a coil for detecting a change in the magnetic field facing the permanent magnet. When the mass is displaced by the acceleration, the magnetic flux of the permanent magnet passing through the detection coil changes, and an induced current flows through the detection coil. The acceleration is detected from the change in the induced current.
かかる加速度センサでは、 検出コイルの誘導電流は磁束の変化の みで生じるため、 検出コイルの誘導電流は、 永久磁石が動いている 時、 即ち質量部が変位している時だけしか発生しない。 従って、 加 速度が一定で質量部の動きがない時には加速度の検出が不可能であ る。 そして、 この加速度センサで検出しているのは加速度の変化分 であり、 加速度そのものを検出するには、 検出信号を積分する回路 等が必要であり回路が複雑となるという問題がある。  In such an acceleration sensor, the induced current of the detection coil is generated only by a change in the magnetic flux. Therefore, the induced current of the detection coil is generated only when the permanent magnet is moving, that is, when the mass is displaced. Therefore, it is impossible to detect acceleration when the acceleration is constant and the mass does not move. What is detected by this acceleration sensor is a change in acceleration. To detect the acceleration itself, a circuit or the like that integrates a detection signal is required, and there is a problem that the circuit becomes complicated.
本発明は上記の事情に鑑みなされたもので、 磁気結合を利用して 加速度を検出する構成とするこ とにより、 ダイナミ ッ ク レ ンジが広 く、 しかも、 高感度で、 回路構成が簡単で製造コス トの極めて安い、 小型化及び薄型化を容易に可能とする加速度センサを提供するこ と を目的とする。  The present invention has been made in view of the above circumstances, and has a configuration in which acceleration is detected using magnetic coupling, whereby a dynamic range is widened, high sensitivity is obtained, and a circuit configuration is simplified. It is an object of the present invention to provide an acceleration sensor that is extremely inexpensive to manufacture and that can be easily reduced in size and thickness.
〔発明の開示〕  [Disclosure of the Invention]
このため、 本発明の加速度センサでは、 枠状のフレームと、 弾性 復元力を有する支持梁を介して前記フ レームに周囲が支持され加速 度に応答して変位する質量部と、 該質量部の前記変位方向の面に配 置される第 1 の平面コイルと、 該第 1 の平面コイルと間隙を設けて 対向配置される第 2の平面コイルとを備え、 前記第 1 の平面コイル と第 2の平面コィルとでトラ ンスを構成したセンサ部を有し、 前記 第 1 の平面コイルに交流信号を印加した伏態で、 加速度に対応する 前記第 1 の平面コイルと第 2の平面コイルとの前記間隙の変化に応 じた電気信号を第 2の平面コイルから取り出す構成と した。 Therefore, in the acceleration sensor of the present invention, the periphery is supported by the frame through the frame-shaped frame and the support beam having the elastic restoring force, and the acceleration is accelerated. A mass portion displaced in response to the temperature, a first planar coil disposed on the surface of the mass portion in the displacement direction, and a second planar coil disposed to face the first planar coil with a gap therebetween. A planar coil; and a sensor unit having a transformer formed by the first planar coil and the second planar coil. The sensor is configured to apply an AC signal to the first planar coil. The electric signal corresponding to the change in the gap between the first planar coil and the second planar coil is taken out from the second planar coil.
かかる構成によれば、 第 1 と第 2の平面コイルとでトランスを形 成して磁気結合を利用して質量部の加速度に対応する変位を検出す るようにしたので、 静電容量型に比べて両平面コイル間の間隙を格 段に大き く とることができ、 半導体基板を利用する場合に、 ゴミ の 付着による影響はなく製造の歩留りが向上して製造コス トを低減で きる。 また、 コイルの巻数を変えて感度を調整するこ とができるの で、 ダイナミ ッ ク レンジが大きレ、にも拘らず高感度にできる。  According to this configuration, a transformer is formed by the first and second planar coils, and a displacement corresponding to the acceleration of the mass portion is detected using magnetic coupling. In comparison, the gap between the two planar coils can be made much larger, and when a semiconductor substrate is used, there is no influence of dust adherence and the production yield is improved, and the production cost can be reduced. In addition, since the sensitivity can be adjusted by changing the number of turns of the coil, high sensitivity can be achieved despite the large dynamic range.
また、 前記質量部を、 互いに直交する中心軸上の 4つの位置でフ レームに支持する構成とすることで、 質量部の変位方向を確実に 1 軸に規制するこ とができ、 多軸感度構造の場合の出力の分離処理が 不要にできる。  In addition, since the mass section is supported by the frame at four positions on the central axis orthogonal to each other, the displacement direction of the mass section can be reliably restricted to one axis, and multi-axis sensitivity can be obtained. Separation of output in case of structure can be eliminated.
また、 前記センサ部を、 マイクロマシニング技術により半導体基 板を加工して形成することで、 容易に小型化及び薄型化ができる。  Further, by forming the sensor section by processing a semiconductor substrate by a micromachining technique, miniaturization and thinning can be easily achieved.
また、 前記センサ部の第 1 の平面コイルに交流信号を印加する発 振器と、 前記第 2の平面コイルから出力される電気信号に基づいて 加速度を演算する電子回路とを備えて構成した。  Further, it is configured to include an oscillator for applying an AC signal to the first planar coil of the sensor section, and an electronic circuit for calculating acceleration based on an electric signal output from the second planar coil.
また、 前記電子回路が、 前記第 2の平面コイルから出力される交 流電気信号を整流する整流回路と、 該整流回路の整流出力をディ ジ タル信号に変換するアナログ一ディ ジタル変換器と、 該アナログ一 ディ ジタル変換器のディ ジタル出力に基づいて加速度を演算するマ イ ク口コ ン ピュータとを備えて構成した場合に、 前記整流回路を、 倍電圧整流回路とすることで、 出力変化を大き く取り出すこ とがで き、 感度を高めるこ とができる。 A rectifier circuit configured to rectify the alternating electric signal output from the second planar coil; an analog-to-digital converter configured to convert a rectified output of the rectifier circuit into a digital signal; A rectifier circuit configured to calculate acceleration based on a digital output of the analog-to-digital converter. By using a voltage doubler rectifier circuit, a large change in output can be taken out, and the sensitivity can be increased.
また、 前記センサ部を、 互いに直交する 2つの面に配置する構成 とすれば、 2軸方向の加速度検出ができる。  Further, if the sensor section is arranged on two surfaces orthogonal to each other, acceleration can be detected in two axial directions.
また、 前記センサ部を、 互いに直交する 3つの面に配置する構成 とすれば、 3軸方向の加速度検出ができ、 ジャイロを含むナビゲー シヨ ンシステムゃ自走ロボッ 卜の位置検出システム等に適用するこ とが可能である。  Further, if the sensor unit is arranged on three surfaces orthogonal to each other, acceleration can be detected in three axial directions, and the present invention is applied to a navigation system including a gyro, a position detection system of a self-propelled robot, and the like. It is possible.
また、 前記センサ部を、 第 1 の平面コイルと第 2の平面コイルに それぞれ近接して設けた磁性体を含んだ構成とすれば、 各コイルの イ ンダクタンスが向上するため両コイルの結合が密になって感度が 向上する。  Further, if the sensor section is configured to include a magnetic body provided in proximity to the first planar coil and the second planar coil, respectively, the inductance of each coil is improved and the coupling between both coils is tight. And the sensitivity is improved.
前記各磁性体を、 板状に形成してセンサ部に積層する構成にすれ ば、 磁性体の加工コス 卜が安く センサ部の組立ても容易である。 〔図面の簡単な説明〕  If each of the magnetic bodies is formed in a plate shape and laminated on the sensor unit, the processing cost of the magnetic body is low and the sensor unit can be easily assembled. [Brief description of drawings]
第 1 図は本発明の加速度センサの一実施例を示すセンサ部の構成 図である。  FIG. 1 is a configuration diagram of a sensor unit showing an embodiment of the acceleration sensor of the present invention.
第 2図は第 1 図の A— A矢視断面図である。  FIG. 2 is a sectional view taken along the line AA of FIG.
第 3図はセンサ部の分解図である。  FIG. 3 is an exploded view of the sensor section.
第 4図は加速度センサの回路構成図である。  FIG. 4 is a circuit configuration diagram of the acceleration sensor.
第 5図は結合係数とコイル間のギヤ ッブとの関係の一例を示すグ ラフである。  Fig. 5 is a graph showing an example of the relationship between the coupling coefficient and the gear between the coils.
第 6図は 2方向の加速度を検出する場合の構成例である。  FIG. 6 is a configuration example in the case of detecting acceleration in two directions.
第 7図は 3方向の加速度を検出する場合の構成例である。  FIG. 7 shows an example of a configuration for detecting acceleration in three directions.
第 8図は本発明の加速度センサのセンサ部に関する別の実施例の 構成図である。  FIG. 8 is a configuration diagram of another embodiment related to the sensor section of the acceleration sensor of the present invention.
第 9図は第 8図のセンサ部の測定実験に用いた回路図である。 第 1 0図は第 8図のセンサ部を用いた加速度センサの出力一加速度 特性を示すグラフである。 FIG. 9 is a circuit diagram used for a measurement experiment of the sensor unit in FIG. Fig. 10 shows the output-acceleration of the acceleration sensor using the sensor unit of Fig. 8. It is a graph which shows a characteristic.
〔発明を実施するための最良の形憨〕  [Best mode for carrying out the invention 憨]
以下、 本発明の一実施例を図面に基づいて説明する。  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
第 1 図〜第 4図に本発明に係る加速度センサの構成を示す。  1 to 4 show the configuration of the acceleration sensor according to the present invention.
第 1 図〜第 3図は、 センサ部の構成を示し、 図において、 セ ンサ 部 1 は、 枠状のフレーム 2の枠内に、 質量部 3が配置される。 質量 部 3は、 互いに直交する中心軸上の 4つの位置、 即ち、 質量部 3 の 各辺の略中心位置で 4本の支持梁 4を介してフ レーム 2に支持され ている。 前記支持梁 4は、 フ レーム 2及び質量部 3に比べて厚さを 薄く形成され、 弾性復元力を有している。 従って、 質量部 3 は、 上 下方向の 1 軸方向のみに加速度に応答して変位可能に構成される。  FIGS. 1 to 3 show the configuration of the sensor unit. In the figure, the sensor unit 1 has a mass unit 3 disposed in a frame 2 having a frame shape. The mass part 3 is supported by the frame 2 via four support beams 4 at four positions on a central axis orthogonal to each other, that is, substantially at the center of each side of the mass part 3. The support beam 4 is formed to be thinner than the frame 2 and the mass portion 3 and has an elastic restoring force. Therefore, the mass unit 3 is configured to be displaceable in response to the acceleration only in one axial direction of the upper and lower directions.
前記質量部 3の上面には、 薄膜の第 1 の平面コイル 5が設けられ ており、 枠状のスぺーサ 6を介在してフ レーム 1 に対面する平板状 の基台 7の上面に、 前記第 1 の平面コィル 5 に対向して薄膜の第 2 の平面コイル 8が設けられている。 そして、 第 1 の平面コイル 5を 一次コイルとし、 第 2の平面コイル 8を 2次コイルとして、 両コィ ル 5， 8によって トランスを構成している。 例えば、 フ レーム 2 と スぺーサ 6の各厚さを 2 0 0 〃mとすれば、 コイル間のギヤ ップ d が 4 0 0 z mの トラ ンスが構成される。  A thin-film first planar coil 5 is provided on the upper surface of the mass unit 3, and is disposed on the upper surface of a flat base 7 facing the frame 1 with a frame-shaped spacer 6 interposed therebetween. A thin-film second planar coil 8 is provided so as to face the first planar coil 5. The first planar coil 5 is a primary coil, the second planar coil 8 is a secondary coil, and the coils 5 and 8 constitute a transformer. For example, if each thickness of the frame 2 and the spacer 6 is 200 μm, a transformer having a gap d between the coils of 400 zm is formed.
フ レーム 2、 支持梁 4及び質量部 3は、 マイ クロマンニング技術 を利用してシ リ コ ン基板を加工して一体形成される。 スぺーサ 6及 び基台 7 も同様にシリ コン基板を加工して形成されたものであり、 第 3図に示すように、 これらを別々に加工形成して互いに重ね合わ せてセンサ部 1 を構成している。  The frame 2, the support beam 4 and the mass 3 are formed integrally by processing a silicon substrate using micromanaging technology. The spacer 6 and the base 7 are also formed by processing a silicon substrate in the same manner, and as shown in FIG. 3, these are separately processed and formed, and are superimposed on each other to form the sensor section 1. Make up.
第 4図に本実施例の加速度センサの回路構成を示す。  FIG. 4 shows a circuit configuration of the acceleration sensor of this embodiment.
図おいて、 前記センサ部 1 の第 1 の平面コイル 5には、 発振器 9 が接続され、 抵抗を介して交流電圧が印加される。 一方、 2次コィ ルとなる第 2の平面コイル 8 には、 整流回路、 例えば 2つのダイォ ー ド D , , D 2 と 2つのコンデンサ（：】 ， C 2 と抵抗 Rからなる倍 電圧整流回路 10が接続されている。 倍電圧整流回路 10からのアナ口 グの整流出力は、 アナログ一ディ ジタル変換器 （以下、 A / D変換 器とする） 1 1でディ ジタル信号に変換され、 マイ クロコ ンピュー夕 12に入力される。 In the figure, an oscillator 9 is connected to the first planar coil 5 of the sensor section 1, and an AC voltage is applied through a resistor. On the other hand, the second planar coil 8 serving as a secondary coil has a rectifier circuit, for example, two diodes. Over de D,, D 2 and two capacitors (:.], Rectified output of Ana port grayed from voltage doubler rectifier circuit 10 is connected voltage doubler rectifier circuit 10 composed of C 2 and a resistor R to an analog one Digital converter (hereinafter referred to as A / D converter) 11 Converted to a digital signal by 1 and input to micro computer 12.
次に、 かかる構成の加速度センサの動作を説明する。  Next, the operation of the acceleration sensor having such a configuration will be described.
センサ部 1 に、 第 1 図中の上下方向の加速度が作用すると、 質量 部 3が加速度方向と反対方向に変位し、 第 1 の平面コイル 5 と第 2 の平面コイル 8 との間のギヤ ッブ dが変化して、 第 1 の平面コイル 5 (—次コイル） と第 2の平面コイル 8 ( 2次コイル） とで構成し た トラ ンスの結合係数が変化し、 第 2の平面コイル 8からの出力電 圧が変化する。  When the vertical acceleration in FIG. 1 acts on the sensor unit 1, the mass unit 3 is displaced in the direction opposite to the acceleration direction, and the gear between the first plane coil 5 and the second plane coil 8 is displaced. And the coupling coefficient of the transformer formed by the first planar coil 5 (—secondary coil) and the second planar coil 8 (secondary coil) changes, and the second planar coil 8 The output voltage from changes.
ここで、 トランスの入力電圧 V i nと出力電圧 V。 との間には、 次 の関係が成立する。 ただし、 下記の式は、 コイルに直流抵抗分がな い理想的なものとした場合である。 Here, the output voltage V. and the input voltage V in of the transformer The following relationship holds between and. However, the following equation is based on the assumption that the coil has no DC resistance.
V 0 = ω · k · V i n V 0 = ω · k · V in
こ こで、 kは トラ ンスの結合係数、 ωは入力電圧の周波数である。 上記の式から、 結合係数 kと出力電圧 V。 とは比例関係にあり、 ω及び V i nを一定とすれば、 2次コイルの出力電圧 V。 を検出する ことで結合係数 kを求めるこ とができる。 この結合係数 kは、 質量 部 3の変位による第 1 の平面コイル 5 と第 2の平面コイル 8 との間 のギャ ップ dに対応するものであり、 センサ部 1 の特性として、 予 め結合係数 k とギャ ップ d との関係を求めておけば、 検出された出 力電圧 V。 から得られた結合係数 kにより、 両コイル 5 , 8 との間 のギャ ップ d、 即ち、 質量部 3の変位量を知るこ とができ、 加速度 が検出できる。 Here, k is the coupling coefficient of the transformer, and ω is the frequency of the input voltage. From the above equation, the coupling coefficient k and the output voltage V. Is proportional to the, if constant ω and V in, the output voltage of the secondary coil V. By detecting, the coupling coefficient k can be obtained. This coupling coefficient k corresponds to the gap d between the first plane coil 5 and the second plane coil 8 due to the displacement of the mass section 3, and as a characteristic of the sensor section 1, If the relationship between the coefficient k and the gap d is determined, the detected output voltage V is obtained. The gap d between the coils 5 and 8, that is, the amount of displacement of the mass section 3 can be known from the coupling coefficient k obtained from, and the acceleration can be detected.
第 5図に、 両コイル間のギャ ップ d と結合係数 k との関係の一例 を示す。 従って、 マイクロコンピュータ 12に、 予め結合係数 k とコイル間 のギャ ップ d との関係を示すマップを記億させておけば、 前記セン サ部 1 の第 2の平面コイル 8からの出力電圧 V。 を、 倍電圧整流回 路 10で整流し、 A Z D変換器 1 1でディ ジ夕ル信号に変換してマイ ク 口コンピュータ （マイコン） 12に入力すると、 マイ クロコンピュー 夕 12において結合係数 kを演算し、 予め記憶された結合係数 kとコ ィル間のギヤ ッブ d との関係を示すマップからコイル間のギヤ ップ dを求めることができ、 質量部 3の変位量が検出でき、 加速度が検 出できる。 Fig. 5 shows an example of the relationship between the gap d between both coils and the coupling coefficient k. Therefore, if the microcomputer 12 preliminarily stores a map showing the relationship between the coupling coefficient k and the gap d between the coils, the output voltage V from the second planar coil 8 of the sensor unit 1 is obtained. . Rectified by the voltage doubler rectifier circuit 10, converted into a digital signal by the AZD converter 11, and input to the micro computer (microcomputer) 12, which calculates the coupling coefficient k in the micro computer 12. Then, the gap d between the coils can be obtained from a map indicating the relationship between the coupling coefficient k and the gear d between the coils, which is stored in advance, and the displacement of the mass section 3 can be detected, and the acceleration can be obtained. Can be detected.
例えば、 入力電圧が交流 10 Vの場合、 ギャ ップ dが mから 10 0 mに変化した時、 第 5図の特性では、 結合係数は 0. 96から 0. 94 に変化するので、 ω = 1 とすれば、 出力電圧 V。 は 9. 6 から9. 4 Vに変化し、 この場合の出力の変化分は、 200 m Vである。  For example, when the input voltage is AC 10 V, when the gap d changes from m to 100 m, the coupling coefficient changes from 0.96 to 0.94 in the characteristics of Fig. 5, so ω = If 1, output voltage V. Changes from 9.6 to 9.4 V, and the output change in this case is 200 mV.
この出力の変化 200 m Vは、 容易に検出できる大きい値であり、 静電容量型ゃ圧電抵抗型の加速度センサに比べて大きい変化を取り 出すこ とができ、 高感度な加速度検出が可能である。 しかも、 両コ ィル 5 , 8 のギャ ップ d も、 静電容量型の 2 m〜 3 mに比べて 数 100 mと格段に大き く、 ダイナミ ッ ク レンジを大き くできる と 共に、 質量部 3 と基台 7 との間の塵の付着の影響がなく、 製造が容 易で歩留りが向上し製造コス トを安くするこ とができる。 更には、 4本の支持梁 4 によって質量部 3の四方を支持しており、 加速度に 応答する質量部 3の移動方向が 1 方向に規制されるので、 多軸感度 構造の場合の出力分離回路等が不要であり、 センサ部 1 からの出力 信号を処理する処理回路が簡単な構成にできる。 また、 第 1 及び第 2の平面コイル 5 , 8を半導体製造技術を利用して製作するこ とで、 手巻や機械巻のコイルの場合に比べて巻線間隔を高精度に作成でき、 理想の相互イ ンダクタンス及び自己イ ンダクタンスの計算式に従つ た理想値に近い値を得る トラ ンスを形成するこ とができ、 加速度の 検出精度を向上できる。 また、 センサ部 1 の出力を整流する整流回 路に倍電圧整流回路 1 0を使用するこ とで、 出力電圧を大き く でき分 解能を高めて検出感度を向上できる。 This output change of 200 mV is a large value that can be easily detected, and can take out a large change compared to the capacitance type ゃ piezoresistive type acceleration sensor, enabling highly sensitive acceleration detection. is there. In addition, the gap d between the two coils 5 and 8 is much larger than the capacitance type of 2 m to 3 m, several hundred meters, and the dynamic range can be increased. There is no influence of the adhesion of dust between the part 3 and the base 7, and the production is easy, the yield is improved, and the production cost can be reduced. Furthermore, since the four sides of the mass part 3 are supported by four support beams 4, the movement direction of the mass part 3 in response to acceleration is restricted to one direction, so the output separation circuit in the case of a multi-axis sensitivity structure And the like are unnecessary, and the processing circuit for processing the output signal from the sensor unit 1 can have a simple configuration. Also, by manufacturing the first and second planar coils 5 and 8 using semiconductor manufacturing technology, the winding interval can be created with higher precision than in the case of manually wound or machine wound coils, and the ideal It is possible to form a transformer that obtains a value close to the ideal value according to the calculation formula of the mutual inductance and self-inductance of Detection accuracy can be improved. Further, by using the voltage doubler rectifier circuit 10 in the rectifier circuit for rectifying the output of the sensor section 1, the output voltage can be increased, the resolution can be increased, and the detection sensitivity can be improved.
上記実施例では、 前記センサ部 1 を 1 つとして 1 方向の加速度を 検出できる場合について説明したが、 例えば、 第 6図に示すように 互いに直交する 2つの面に前記センサ部 1 をそれぞれ配置するこ と で、 2方向、 即ち 2次元の加速度検出が可能であり、 第 7図に示す ように、 互いに直交する 3つの面に前記センサ部 1 をそれぞれ配置 するこ とで 3次元の加速度検出ができる。  In the above-described embodiment, the case has been described in which one sensor unit 1 can be used as one to detect acceleration in one direction.For example, as shown in FIG. 6, the sensor units 1 are respectively arranged on two surfaces orthogonal to each other. In this way, it is possible to detect acceleration in two directions, that is, in two dimensions. As shown in FIG. 7, by arranging the sensor units 1 on three surfaces orthogonal to each other, three-dimensional acceleration can be detected. it can.
そして、 第 7図のように 3次元の加速度検出可能な構成とすれば、 自動車等のナビゲージヨ ンシステムゃ自走ロボッ 卜の位置検出シス テムに適用するこ とができる。 尚、 1 次元の加速度検出構造では、 自動車用のアクティブサスペンショ ン等に適用するこ とができる。 第 8図に、 本発明の加速度センサのセンサ部の別の実施例を示す c 第 8図の実施例は、 加速度センサの感度を向上させるために第 1 図に示すセンサ部に磁性体を装着した場合の例である。 尚、 第 1 図 の実施例と同一要素は同一符号を付して説明を省略する。 Then, as shown in FIG. 7, if the configuration is such that three-dimensional acceleration can be detected, it can be applied to a navigation system for automobiles or the like and a position detection system for self-propelled robots. In addition, the one-dimensional acceleration detection structure can be applied to active suspension for automobiles and the like. In FIG. 8, an embodiment of Figure 8 c shows another embodiment of a sensor portion of the acceleration sensor of the present invention, mounting a magnetic sensor section shown in FIG. 1 in order to improve the sensitivity of the acceleration sensor This is an example in the case of performing. The same elements as those of the embodiment shown in FIG.
第 8図において、 本実施例のセンサ部 20は、 枠状のフ レーム 2 の 枠内に、 弾性復元力を有する 4本の支持梁 4 を介して薄膜の第 1 の 平面コイル 5を設けた質量部 3が配置され、 枠状のスぺーサ 6を介 在して第 2の平面コイル 8を有する基台 7が前記質量部 3 と所定の 間隔を有して設けられていることは第 1 図のセンサ部 1 と同様であ る。 そして、 前記質量部 3上面側及び基台 7底面側に、 それぞれ板 状の第 1 及び第 2の磁性体 21 , 22を装着している。  In FIG. 8, the sensor section 20 of the present embodiment has a thin-film first planar coil 5 provided in a frame of a frame 2 through four support beams 4 having elastic restoring force. The mass part 3 is disposed, and a base 7 having a second planar coil 8 is provided at a predetermined interval from the mass part 3 via a frame-shaped spacer 6. This is the same as sensor unit 1 in Fig. 1. Then, plate-shaped first and second magnetic bodies 21 and 22 are mounted on the upper surface side of the mass unit 3 and the bottom surface side of the base 7, respectively.
第 1 の磁性体 21は、 質量部 3 と略同等の大きさの板状に形成され て質量部 3上面を覆って装着される。 従って、 第 1 の磁性体 21は、 加速度に応答して質量部 3 と一体に変位可能であり、 質量部 3 の一 部となる。 第 2の磁性体 22は、 第 2の平面コイル 8を設けた基台 7 と略同等の大きさの板状に形成され、 基台 7の底面側に装着されて いる。 第 1 及び第 2の磁性体 21 , 22は、 例えば、 M n — Z n フ ェ ラ ィ ト材等で形成される。 The first magnetic body 21 is formed in a plate shape having substantially the same size as the mass part 3 and is mounted so as to cover the upper surface of the mass part 3. Therefore, the first magnetic body 21 can be displaced integrally with the mass section 3 in response to the acceleration, and becomes a part of the mass section 3. The second magnetic body 22 includes a base 7 on which the second planar coil 8 is provided. It is formed in a plate shape approximately the same size as that of the base 7 and is mounted on the bottom side of the base 7. The first and second magnetic bodies 21 and 22 are made of, for example, Mn-Zn ferrite material.
かかる構成では、 前記第 1 及び第 2の磁性体 21 , 22が、 第 1 及び 第 2の平面コイル 5 , 8で構成される トランスの鉄芯の機能を果た し、 第 1 及び第 2の平面コイル 5， 8のイ ンダクタンスが向上する, これにより、 第 1 の平面コイル 5 に電流を流した時に発生する磁束 密度が増大する。 磁束密度が増大すると第 2の平面コイル 8 に鎖交 する磁束も増大するため、 コイル間の結合が第 1 図に示す磁性体の ない空芯のものに比べて密となる。 従って、 第 1 及び第 2のコイル 5 , 8間の距離による変化分も増加するので加速度センサの感度が 向上する。  In such a configuration, the first and second magnetic bodies 21 and 22 function as an iron core of a transformer including the first and second planar coils 5 and 8, and the first and second magnetic bodies The inductance of the planar coils 5 and 8 is improved, so that the magnetic flux density generated when a current flows through the first planar coil 5 increases. When the magnetic flux density increases, the magnetic flux linked to the second planar coil 8 also increases, so that the coupling between the coils becomes denser than that of the air core without a magnetic material shown in FIG. Therefore, the amount of change due to the distance between the first and second coils 5 and 8 also increases, and the sensitivity of the acceleration sensor improves.
ところで、 本発明の トラ ンス結合を利用した加速度センサの感度 を向上させる方法としては、 1 次コイルに印加する交流電流の振幅 を大き くする方法、 1 次コイルと 2次コイルとの間の間隔を狭くす る方法等が考えられる。  By the way, as a method of improving the sensitivity of the acceleration sensor using the transformer coupling of the present invention, a method of increasing the amplitude of an alternating current applied to the primary coil, a method of increasing a distance between the primary coil and the secondary coil, and the like. For example, a method of narrowing the width can be considered.
しかし、 前者の方法では、 1 次コイルに流れる電流値が大き く な ると 1 次コイルそのものの抵抗 （銅損） による発熱が問題となり、 コイルの抵抗値を低減する必要がある。 コイルの抵抗値を低減する には、 コイルの断面積を増加させればよいが、 同一面積内で同一巻 き数のコイルを考えると、 コイルの断面積を増加させるには高さの み増加させる高ァスぺク ト比のパターニング技術を用いるこ とにな るが、 アスペク ト比が高い程製造コス トが幾何級数的に増大してし まう。  However, in the former method, if the current flowing through the primary coil increases, heat generation due to the resistance (copper loss) of the primary coil itself becomes a problem, and it is necessary to reduce the coil resistance. To reduce the resistance value of the coil, it is sufficient to increase the cross-sectional area of the coil.However, considering coils with the same number of turns in the same area, only the height is increased to increase the cross-sectional area of the coil. Although a patterning technique with a high aspect ratio is used, the manufacturing cost increases exponentially as the aspect ratio increases.
また、 後者の方法では、 質量部の動ける距離が小さ く なり測定レ ンジが狭く なる。 また、 1 次コイルと 2次コイルとの間に塵が存在 した場合に塵によって質量部の動きが制限され誤差が生じる可能性 が大きい。 塵は一股的にデバイスが小さい程存在確率が高く なるの で、 デバイスをパッケージングして出荷するとすれば製造工程での 塵の混入が問題となり、 コイル間の間隙を狭く しょう とすれば製造 現場に高ク リーン度が要求され製造コス トの増加を招く。 Also, in the latter method, the moving distance of the mass part becomes shorter, and the measuring range becomes narrower. In addition, if dust exists between the primary coil and the secondary coil, the movement of the mass is restricted by the dust, and there is a high possibility that an error will occur. The smaller the device, the higher the probability of the presence of dust Therefore, if the device is packaged and shipped, dust will be a problem in the manufacturing process, and if the gap between the coils is to be narrowed, a high degree of cleanliness will be required at the manufacturing site, leading to an increase in manufacturing costs. .
本発明の磁性体を設ける方法によれば、 下記に示す特性の測定結 果から上述の各方法における問題が生じないこ とは明らかである。 第 9図に示すように、 交流電源 23に第 1 の平面コイル 5を接続し. 第 2の平面コイル 8側に、 2つのダイオー ド D、 コンデンサ C及び 抵抗 Rを図示の如く接続した回路を用いて測定を行った。  According to the method for providing a magnetic body of the present invention, it is clear from the measurement results of the characteristics shown below that no problem occurs in each of the above methods. As shown in Fig. 9, the first plane coil 5 is connected to the AC power supply 23. A circuit in which two diodes D, a capacitor C and a resistor R are connected as shown in the figure is connected to the second plane coil 8 side. The measurement was carried out.
第 1 の平面コイル （ 1 次コイルに相当する） への入力電圧 V I Nを 3 V P - P とすると、 第 1 図の空芯のセンサ部 1 の場合は出力電圧 V 。u l は 3 m V程度であるのに対し、 第 8図の磁性体 21 , 22を設けた センサ部 20の場合は 3 0 0 m V程度が得られ、 出力は約 1 0 0倍で あり、 感度が大幅に向上する。 また、 第 1 の平面コイル 5の入カイ ンピーダンスは、 同じ電圧を入力した場合、 空芯の時は約 4オーム ( 1 M H z , そのうち 2オームは銅損） であるのに対し、 磁性体を 装着した時は約 4 5オーム （ 1 M H z , そのうち 2オームは銅損） であり、 第 1 の平面コイル 5の入力イ ンピーダンスが空芯の時と比 較して大幅に増加している。 従って、 同一の入力電圧に対して第 1 の平面コイル 5に流れる電流は空芯の時に比較して 1 桁小さ く なる。 このため、 第 1 の平面コイル 5での発熱量は大幅に抑制できる。 Assuming that the input voltage V IN to the first planar coil (corresponding to the primary coil) is 3 VP-P, the output voltage V is shown for the air-core sensor unit 1 in Fig. 1. ul is about 3 mV , whereas in the case of the sensor unit 20 provided with the magnetic bodies 21 and 22 in FIG. 8, about 300 mV is obtained, and the output is about 100 times. The sensitivity is greatly improved. When the same voltage is input, the input impedance of the first planar coil 5 is approximately 4 ohms (1 MHz, 2 ohms of which are copper loss) when the core is air-core. When installed, it is approximately 45 ohms (1 MHz, of which 2 ohms is copper loss), and the input impedance of the first planar coil 5 is greatly increased compared to when it is air-core. Therefore, the current flowing through the first planar coil 5 for the same input voltage is one order of magnitude smaller than when the air core is used. Therefore, the amount of heat generated by the first planar coil 5 can be significantly reduced.
即ち、 抵抗による発熱量 Pは、  That is, the heat value P due to the resistance is
P = i 2 R P = i 2 R
で表される。 ここで、 i はコイルに流れる電流、 Rは銅損である。 今、 Rは一定であるから、 発熱量 Pは、 1 1 0 0 になるこ とがわ 力、る。 It is represented by Here, i is the current flowing through the coil, and R is the copper loss. Now, since R is constant, the calorific value P is known to be 110.
更に、 磁束密度が増加するため、 コイル間の距離を狭く しなく と も充分な測定感度を得ることができ測定範囲を拡大できる。  Furthermore, since the magnetic flux density is increased, sufficient measurement sensitivity can be obtained without reducing the distance between the coils, and the measurement range can be expanded.
また、 磁性体 21， 22を、 簡単な形状の板状としてセンサ部に積層 するようにすれば加工費も安い。 磁性体の材質として、 一般的に用 いられるフ ェライ ト等の材料を用いれば安価であり、 空芯のものに 比較して大きなコス トアップを招く こともない。 In addition, magnetic materials 21 and 22 are laminated on the sensor as a simple plate. If you do, the processing cost will be low. If a material such as ferrite, which is generally used, is used as the material of the magnetic material, it is inexpensive and does not cause a large cost increase as compared with an air core material.
第 1 0図には、 第 8図に示すセンサ部 20の出力電圧—加速度の関係 を示す。  FIG. 10 shows the relationship between the output voltage and the acceleration of the sensor unit 20 shown in FIG.
尚、 第 8図のセンサ部 20に関しても、 第 6図のように、 互いに直 交する 2つの面にそれぞれ配置すれば 2次元の加速度検出が可能で あり、 第 7図のように、 互いに直交する 3つの面にそれぞれ配置す れぱ 3次元の加速度検出ができるこ とは言うまでもない。  It is to be noted that two-dimensional acceleration can be detected by arranging the sensor units 20 in FIG. 8 on two surfaces orthogonal to each other as shown in FIG. 6, and orthogonal to each other as shown in FIG. It is needless to say that three-dimensional acceleration can be detected.
以上説明したように本発明によれば、 加速度に応答して変位する 質量部と固定部に互いに対向する平面コイルを設けて トラ ンスを構 成し、 両コイル間の磁気結合を利用してコイル間のギャ ップ、 即ち 質量部の変位を検出する構成としたので、 従来の静電容量型に比べ て質量部と固定部との間のギャ ップを格段に大き くでき、 製造が容 易で、 ギャ ップ間の塵付着による影響がなく、 製造コス トを安くで きると共に、 ダイナミ ッ ク レンジを広く とれる。 また、 コイル巻数 を調整することで感度の調整が自由にできるので、 高感度にできる ( 従って、 小型且つ薄型であり、 高感度の加速度センサを低コス トで 提供するこ とができる。 As described above, according to the present invention, the mass is displaced in response to the acceleration and the fixed portion is provided with a planar coil facing each other to constitute a transformer, and the coil is formed by using the magnetic coupling between the two coils. Since the gap between the mass part and the displacement of the mass part is detected, the gap between the mass part and the fixed part can be much larger than that of the conventional capacitance type, and the manufacturing is easy. It is easy, is not affected by dust adhesion between gaps, can reduce manufacturing costs, and can have a wide dynamic range. Further, since the sensitivity can be freely adjusted by adjusting the number of coil turns, high sensitivity can be achieved ( accordingly, a small and thin, high-sensitivity acceleration sensor can be provided at low cost.
尚、 感度の調整が可能であるので、 低感度にもできることは言う までもなく 、 用途に応じた感度のものを製造することができる。  In addition, since the sensitivity can be adjusted, it is needless to say that the sensitivity can be reduced, and that the sensitivity can be manufactured according to the intended use.
〔産業上の利用可能性〕  [Industrial applicability]
本発明は、 小型且つ薄型で、 高感度の加速度センサを低コス トで 提供するこ とができ、 加速度センサを使用するシステムの制御精度 の向上及び低コス ト化を図ることができ、 産業上利用性は大である  INDUSTRIAL APPLICABILITY The present invention can provide a small, thin, high-sensitivity acceleration sensor at low cost, and can improve control accuracy and reduce cost of a system using an acceleration sensor. Usability is great

Claims

請求 の 範 囲 The scope of the claims
( 1 ) 枠状のフ レームと、 弾性復元力を有する支持梁を介して前記 フ レームに周囲が支持され加速度に応答して変位する質量部と、 該 質量部の前記変位方向の面に配置される第 1 の平面コイルと、 該第 (1) A frame-shaped frame, a mass portion whose periphery is supported by the frame via a support beam having elastic restoring force, and which is displaced in response to acceleration, and arranged on a surface of the mass portion in the displacement direction. A first planar coil to be
1 の平面コイルと間隙を設けて対向配置される第 2の平面コイルと を備え、 前記第 1 の平面コイルと第 2の平面コイルとで トラ ンスを 構成したセンサ部を有し、 前記第 1 の平面コイルに交流信号を印加 した伏態で、 加速度に対応する前記第 1 の平面コイルと第 2の平面 コイルとの前記間隙の変化に応じた電気信号を第 2の平面コイルか ら取り出す構成としたことを特徴とする加速度センサ。 A first planar coil and a second planar coil opposed to each other with a gap provided between the first planar coil and the second planar coil. A configuration in which an AC signal is applied to the first planar coil and an electric signal corresponding to a change in the gap between the first planar coil and the second planar coil corresponding to the acceleration is extracted from the second planar coil. An acceleration sensor, characterized in that:
( 2 ) 前記質量部は、 互いに直交する中心軸上の 4つの位置で支持 梁を介してフ レームに支持される構成である請求項 1 記載の加速度 センサ。  (2) The acceleration sensor according to claim 1, wherein the mass section is configured to be supported by the frame via support beams at four positions on a central axis orthogonal to each other.
( 3 ) 前記センサ部が、 半導体基板で構成される請求項 1 記載の加 速度センサ。  (3) The acceleration sensor according to claim 1, wherein the sensor unit is formed of a semiconductor substrate.
( 4 ) 前記センサ部の第 1 の平面コイルに交流信号を印加する発振 器と、 前記第 2の平面コィルから出力される電気信号に基づいて加 速度を演算する電子回路とを備えて構成した請求項 1 記載の加速度 センサ。  (4) An oscillator for applying an AC signal to a first plane coil of the sensor unit, and an electronic circuit for calculating acceleration based on an electric signal output from the second plane coil. The acceleration sensor according to claim 1.
( 5 ) 前記電子回路が、 前記第 2の平面コイルから出力される交流 電気信号を整流する整流回路と、 該整流回路の整流出力をデイ ジ夕 ル信号に変換するアナログ一ディ ジタル変換器と、 該アナ口グーデ ィ ジタル変換器のディ ジタル出力に基づいて加速度を演算するマイ クロコ ンピュータとを備えてなる請求項 4記載の加速度センサ。 (5) The electronic circuit includes: a rectifier circuit that rectifies an AC electric signal output from the second planar coil; and an analog-to-digital converter that converts a rectified output of the rectifier circuit into a digital signal. 5. The acceleration sensor according to claim 4, further comprising: a micro computer that calculates an acceleration based on a digital output of the analog-to-digital converter.
( 6 ) 前記整流回路が、 倍電圧整流回路である請求項 5記載の加速 度センサ。 (6) The acceleration sensor according to claim 5, wherein the rectifier circuit is a voltage doubler rectifier circuit.
( 7 ) 前記センサ部を、 互いに直交する 2つの面に配置して構成し た請求項 1 記載の加速度センサ。 (7) The acceleration sensor according to claim 1, wherein the sensor unit is arranged on two surfaces orthogonal to each other.
( 8 ) 前記センサ部を、 互いに直交する 3つの面に配置して構成し た請求項 1 記載の加速度センサ。 (8) The acceleration sensor according to claim 1, wherein the sensor units are arranged on three surfaces orthogonal to each other.
( 9 ) 前記センサ部が、 第 1 の平面コイルと第 2の平面コィルにそ れぞれ近接して設けた磁性体を含んで構成される請求項 1 記載の加 速度センサ。  (9) The acceleration sensor according to claim 1, wherein the sensor unit includes a magnetic body provided in close proximity to each of the first planar coil and the second planar coil.
( 10) 前記各磁性体は、 板状に形成してセンサ部に積層する構成で ある請求項 9記載の加速度センサ。  (10) The acceleration sensor according to claim 9, wherein each of the magnetic bodies is formed in a plate shape and stacked on a sensor unit.
PCT/JP1995/002556 1994-12-20 1995-12-13 Acceleration sensor WO1996019733A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US08/693,282 US5763783A (en) 1994-12-20 1995-12-13 Acceleration sensor
PCT/JP1995/002556 WO1996019733A1 (en) 1994-12-20 1995-12-13 Acceleration sensor
EP95940428A EP0745858B1 (en) 1994-12-20 1995-12-13 Acceleration sensor
DE69525935T DE69525935T2 (en) 1994-12-20 1995-12-13 ACCELERATION SENSOR

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JPPCT/JP94/02158 1994-12-20
PCT/JP1995/002556 WO1996019733A1 (en) 1994-12-20 1995-12-13 Acceleration sensor

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WO1996019733A1 true WO1996019733A1 (en) 1996-06-27

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2175283A1 (en) 2008-10-08 2010-04-14 Honeywell International MEMS accelerometer
WO2023228886A1 (en) * 2022-05-23 2023-11-30 国立大学法人 東京大学 Information processing device, information analysis system, and measurement method

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05142246A (en) * 1991-11-18 1993-06-08 Omron Corp Acceleration sensor

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
JPH05142246A (en) * 1991-11-18 1993-06-08 Omron Corp Acceleration sensor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2175283A1 (en) 2008-10-08 2010-04-14 Honeywell International MEMS accelerometer
US8065915B2 (en) 2008-10-08 2011-11-29 Honeywell International Inc. MEMS accelerometer
WO2023228886A1 (en) * 2022-05-23 2023-11-30 国立大学法人 東京大学 Information processing device, information analysis system, and measurement method

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