JP2008232703A - Inertia force sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inertia force sensor having heightened detection sensitivity. <P>SOLUTION: This sensor is equipped with a detection element 1 having an acceleration detection part and an angular velocity detection part. The detection element 1 has two orthogonal arms wherein the first arm 8 is connected to the second arm 10 approximately in the orthogonal direction, and has a constitution described as follows: the first arm 8 is a T-shaped orthogonal arm wherein the first connection arm 11 is arranged orthogonally to the second connection arm 13; one end of the first connection arm 11 is supported by a support part 12 and connected to a weight part 2 through the second arm 10; the other end of the first connection arm 11 is connected to the orthogonal second connection arm 13; both ends of the second connection arm 13 is connected to a frame body part 4; each thickness of the first arm 8 and the second connection arm 13 is formed extremely more thinly than the thickness of the second arm 10 or the weight part 2; and the first arm 8 and the second arm 10 are arranged mutually in the orthogonal direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to sensors used in various electronic devices such as attitude control and navigation of moving bodies such as aircraft, automobiles, robots, ships, and vehicles.

  Hereinafter, an acceleration sensor which is one of conventional inertial force sensors will be described.

  FIG. 12 is a plan view of a detection element of a conventional acceleration sensor, FIG. 13 is an AA sectional view of the detection element, and FIG. 14 is a BB sectional view of the detection element.

  12 to 14, the conventional acceleration sensor includes a detection element 51 that detects acceleration, and a processing circuit (not shown) that detects acceleration by performing arithmetic processing on an acceleration signal output from the detection element 51. ing. The detection element 51 includes a support portion 54 that supports the weight portion 52 and a fixing portion 58 that is connected to the support portion 54 via a flexible portion 56. It is mounted on the mounting board.

  The flexible portion 56 has an arm shape, and the flexible portion 56 is arranged in a cross shape with the support portion 54 as the center, and the pair of flexible portions 56 and the support portion 54 are arranged on the same straight line. I try to do it.

  A strain resistance element 58 is provided in the flexible portion 56, and a change in resistance value of the strain resistance element 58 is output as an acceleration signal based on a change in the state of the flexible portion 56 that is bent due to the movement of the weight portion 52. ing.

  Next, detection of acceleration will be described.

  When the flexible portion 56 formed of a cross-shaped arm is arranged in the X axis direction and the Y axis direction on the X axis, the Y axis, and the Z axis orthogonal to each other, for example, when acceleration occurs in the X axis direction, the weight portion 52 Of the two flexible portions 56 arranged in the X-axis direction, one of the flexible portions 56 bends in the positive direction of the Z-axis. The other flexible portion 56 bends in the negative direction of the Z-axis (the bend portion 52 is bent as the weight 52 tries to rotate in the Z-axis direction around the support portion 54). Then, the two strain resistance elements 58 provided in the two flexible portions 56 also bend in the positive and negative directions of the Z axis according to the flexure of the flexible portion 56, so that the resistance value of the strain resistance element 58 changes. This resistance value change is output as an acceleration signal to detect acceleration.

  Such an acceleration sensor is used in a posture control device, a navigation device, or the like of a moving body such as a vehicle corresponding to a detection axis to be detected.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 10-48243

  In the above configuration, since the arm-shaped flexible portion 56 is arranged in a cross shape with the support portion 54 as the center, the weight portion 52 is formed by the flexible portion 56 arranged in the axial direction in which acceleration occurs. Movement is restricted. Of the two flexible portions 56 arranged in the X-axis direction, one of the flexible portions 56 bends in the positive direction of the Z-axis, and the other flexible portion 56 has a negative direction of the Z-axis. Deflection occurs.

  At this time, in FIG. 12, when acceleration occurs in the X-axis direction, the weight part 52 tries to move in the X-axis direction, but the movement of the weight part 52 is caused by the flexible part 56 arranged in the X-axis direction. Be regulated. Due to this restriction, the weight portion 52 tends to rotate in the Z-axis direction around the support portion 54, so that the flexible portion 56 bends, but the amount of the bend is small and the resistance value change of the strain resistance element 58 is also small. However, the detection sensitivity is low.

  The present invention solves the above-described problems, and an object thereof is to provide an inertial force sensor with increased detection sensitivity.

  In order to achieve the above object, in particular, the present invention provides a detecting element having a weight portion connected via a connecting portion, and a frame body portion in which the weight portion is disposed inward, and a facing portion facing the weight portion. A substrate, and a counter electrode disposed on each counter surface of the weight portion and the counter substrate. In the acceleration detection unit, between the counter electrodes disposed on the counter surfaces of the weight portion and the counter substrate An acceleration is detected by detecting a change in capacitance, and the connecting part is an orthogonal arm in which the first connecting arm is orthogonal to the second connecting arm, and one end of the first connecting arm is connected to the weight part. And both end portions of the second arm are connected to the frame body portion, and the thickness of the first connection arm and the thickness of the second connection arm are made thinner than the thickness of the weight portion. .

  With the above configuration, for example, when the first connecting arm is arranged in the X-axis direction and the second connecting arm is arranged in the Y-axis direction on the X-axis, Y-axis, and Z-axis that are orthogonal to each other, acceleration occurs in the Y-axis direction. Since the weight portion tends to rotate around the X axis with the first connecting arm as an axis, the capacitance between the weight portion and the counter electrode of the counter substrate changes. The weight portion rotates in the Z-axis direction because the thickness of the first connecting arm is thinner than the thickness of the weight portion, so that the center of gravity position of the weight portion in the Z-axis direction is shifted from the center of gravity position of the first connecting arm. This is because the center of gravity of the first connection arm tries to rotate around the first connection arm and the first connection arm twists. Since the twist of the first connecting arm is easily generated when acceleration occurs, the capacitance between the counter electrodes is easily changed, and the detection sensitivity can be improved.

  Further, when acceleration occurs in the X-axis direction, the weight portion tends to rotate in the Z-axis direction around the second connection arm arranged in a direction orthogonal to the first connection arm, so that the weight portion and the counter substrate face each other. The capacitance between the electrodes changes. Similarly to the above, the weight part rotates in the Z-axis direction because the thickness of the second connecting arm is thinner than the weight part, so that the center of gravity position of the weight part and the center of gravity of the second connecting arm in the Z-axis direction. This is due to the fact that the center of gravity of the weight portion tries to rotate around the second connecting arm and the second connecting arm twists. Since the twist of the second connecting arm is easily generated when acceleration occurs, the capacitance between the counter electrodes is easily changed, and the detection sensitivity can be improved.

  In particular, when detecting the acceleration in the X-axis direction and the Y-axis direction, the acceleration in the Y-axis direction is detected by the weight portion rotating in the Z-axis direction around the first connecting arm, and the acceleration in the X-axis direction is It is detected by rotating the weight portion in the Z-axis direction with the second connecting arm as an axis, and each can be detected independently, and a reduction in detection can be suppressed.

(Embodiment 1)
1 is an exploded perspective view of a detection element of a composite sensor according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG.

  In FIG. 1, the composite sensor according to the first embodiment of the present invention includes a detection element 1 having an acceleration detection unit and an angular velocity detection unit, and an acceleration signal and an angular velocity signal output from the detection element 1 by arithmetic processing. A processing circuit (not shown) for detecting acceleration and angular velocity is provided.

  The detection element 1 connects a weight part 2 via a connection part, and includes a frame-like frame body part 4 in which the weight part 2 is disposed inward, and a counter substrate 6 facing the weight part 2. And is fixed to the mounting substrate by the frame portion 4.

  Specifically, it has two orthogonal arms in which the first arm 8 is connected to the second arm 10 in a substantially orthogonal direction, and one end of each of the two first arms 8 is supported by the support portion 12. The other end of the arm 8 is connected to the frame body portion 4. The second arm 10 is bent in a U shape until it faces the second arm 10 itself, and the weight portion 2 is connected to the tip of the bent second arm 10.

  The first arm 8 is a T-shaped orthogonal arm in which the first connection arm 11 is orthogonal to the second connection arm 13, and one end of the first connection arm 11 is supported by the support portion 12. It is connected to the weight part 2 via the second arm 10, the other end of the first connection arm 11 is connected to a second connection arm 13 that is orthogonal, and both ends of the second connection arm 13 are frame parts. 4 is connected. At this time, both end portions of the second connection arm 13 are extended in the direction orthogonal to the first connection arm 11 and connected to the frame body portion 4.

  The first connecting arm 11 and the support portion 12 are arranged on substantially the same straight line, and the first arm 8 and the second arm 10 are arranged symmetrically with respect to the center of the detection element 1, and the thickness of the first connecting arm 11 and The thickness of the second connecting arm 13 is made much thinner than the thickness of the weight portion 2.

  Further, the counter substrate 6 is disposed so as to face the weight portion 2, and the first to fourth counter electrodes 14, 16, 18, and 20 are disposed on the respective facing surfaces of the weight portion 2 and the counter substrate 6. ing. Furthermore, a drive electrode 22 that drives and vibrates the weight portion 2 and a detection electrode 24 that detects the drive of the weight portion 2 are arranged on one of the two second arms 10 that face each other, and the other two second arms 10 that face each other. The first sensing electrode 26 and the second sensing electrode 28 for sensing the distortion of the second arm 10 are arranged. Among these electrodes, at least the drive electrode 22, the detection electrode 24, the first sensing electrode 26, and the second sensing electrode 28 are composed of an upper electrode and a lower electrode with a piezoelectric layer interposed therebetween.

  Signal lines (not shown) are framed from the first to fourth counter electrodes 14, 16, 18, 20, the drive electrode 22, the detection electrode 24, and the first and second detection electrodes 26, 28. It is pulled out to the portion 4 and is electrically connected to the wiring pattern of the mounting substrate through wire bonding or the like at the end of the signal line.

  Next, the angular velocity detection unit and the acceleration detection unit will be described.

  First, the angular velocity detection unit will be described. As shown in FIG. 4, when the first arm 8 of the detection element 1 is arranged in the X-axis direction and the second arm 10 is arranged in the Y-axis direction on the X axis, the Y axis, and the Z axis orthogonal to each other, When an AC voltage having a resonance frequency is applied to the drive electrode 22, the second arm 10 is driven to vibrate starting from the second arm 10 on which the drive electrode 22 is disposed, and accordingly, the weight portion 2 is also opposed to the second arm 10. Drive vibration occurs in the drive vibration direction indicated by the solid arrow and the dotted arrow. Further, all of the four second arms 10 and the four weight portions 2 are synchronously driven and vibrated in a direction opposite to the second arm 10 (drive signal direction). The driving vibration direction in the detection element 1 is the X-axis direction.

  At this time, for example, when an angular velocity is generated around the left of the Z-axis, in synchronization with the drive vibration of the weight portion 2, a direction perpendicular to the drive vibration direction with respect to the weight portion 2 (solid arrow and dotted arrow) Since the Coriolis force is generated in the Coriolis direction (Y-axis direction) described above, distortion caused by the angular velocity around the left of the Z-axis can be generated in the second arm 10. That is, a voltage is output from the first and second sensing electrodes 26 and 28 due to a change in the state of the second arm 10 that is bent due to the Coriolis force (a strain generated in the second arm 10). Based on this, the angular velocity is detected.

  Next, the acceleration detection unit will be described.

  First, acceleration in the X-axis direction will be described. As shown in FIGS. 1 and 5, when the counter substrate 6 is arranged on the XY plane in the X axis, the Y axis, and the Z axis orthogonal to each other, if the acceleration is not generated, the substrate 6 and the weight portion 2 are opposed to each other. The opposing distance (H1) of the first opposing electrode 14 on the surface and the opposing distance (H2) of the second opposing electrode 16 on the opposing surface of the substrate 6 and the weight part 2 are equal, although not shown, the third opposing electrode The opposing distance of 18 and the opposing distance of the fourth counter electrode 20 are also equal.

  At this time, for example, when acceleration occurs in the X-axis direction, as shown in FIGS. 1 and 6, the weight portion 2 rotates around the Y-axis around the second connecting arm 13 arranged in the Y-axis direction. try to. As a result, the facing distance (H1) of the first counter electrode 14 on the facing surface of the substrate 6 and the weight portion 2 is reduced, and the facing distance (H2) of the second facing electrode 16 on the facing surface of the substrate 6 and the weight portion 2 is reduced. Becomes larger. The same applies to the facing distance of the third counter electrode 18 and the facing distance of the fourth counter electrode 20.

  Next, the acceleration in the Y-axis direction will be described. As shown in FIGS. 1 and 7, when the counter substrate 6 is arranged on the XY plane in the X axis, the Y axis, and the Z axis orthogonal to each other, if the acceleration is not generated, the substrate 6 and the weight portion 2 are opposed to each other. The opposing distance (H1) of the first opposing electrode 14 on the surface and the opposing distance (H2) of the third opposing electrode 18 on the opposing surface of the substrate 6 and the weight portion 2 are equal. Although not shown, the facing distance of the second counter electrode 16 and the facing distance of the fourth counter electrode 20 are also equal.

  At this time, when acceleration occurs in the Y-axis direction, as shown in FIGS. 1 and 8, the weight portion 2 tries to rotate around the X-axis around the first connecting arm 11 arranged in the X-axis direction. Therefore, for example, the facing distance between the third and fourth counter electrodes 18 and 20 is increased, and the facing distance between the first and second counter electrodes 14 and 16 is decreased.

  That is, since the capacitance between the electrodes changes, acceleration in the X-axis direction or Y-axis direction is detected based on the change in capacitance.

  With the above configuration, the acceleration is detected by detecting the capacitance of the first to fourth counter electrodes 14, 16, 18, and 20 disposed on the opposing surfaces of the weight portion 2 and the substrate 6 by the acceleration detection unit. Then, the angular velocity detection unit can detect the change in the state of the flexible portion caused by the Coriolis force by the first and second sensing electrodes 26 and 28, and the acceleration and angular velocity can be detected by the single detection element 1. The mounting area can be reduced and the size can be reduced.

  For example, when the first connecting arm 11 is arranged in the X-axis direction and the second connecting arm 13 is arranged in the Y-axis direction on the X-axis, Y-axis, and Z-axis orthogonal to each other, acceleration occurs in the Y-axis direction. Then, since the weight portion 2 tends to rotate around the X axis with the first connecting arm 11 as an axis, the capacitance between the weight portion 2 and the counter electrode of the counter substrate 6 changes. The weight 2 rotates around the X axis because the thickness of the first connecting arm 11 is thinner than the thickness of the weight 2, so that the center of gravity position of the weight and the center of gravity of the first connecting arm 11 in the Z-axis direction are This is because the center of gravity of the weight portion 2 tries to rotate around the first connecting arm 11 and the first connecting arm 11 is twisted. Since the twist of the first connecting arm 11 is easily generated when acceleration occurs, the capacitance between the counter electrodes is easily changed, and the detection sensitivity can be improved.

  Further, when acceleration occurs in the X-axis direction, the weight part 2 tends to rotate around the Y-axis with the second connection arm 13 arranged in a direction orthogonal to the first connection arm 11 as an axis. The capacitance between the counter electrodes of the counter substrate 6 changes. Similarly to the above, the weight portion 2 rotates around the Y axis because the thickness of the first connecting arm 11 is thinner than the weight portion 2, and the position of the center of gravity of the weight portion 2 in the Z-axis direction and the first connection This is because the position of the center of gravity of the arm 11 is shifted, and the center of gravity of the weight portion 2 tries to rotate around the second connection arm 13 and the second connection arm 13 is twisted. Since the twist of the second connecting arm 13 is easily generated when acceleration occurs, the capacitance between the counter electrodes is easily changed, and the detection sensitivity can be improved. At this time, since the two second connecting arms 13 are arranged opposite to each other, for example, one of the second connecting arms 13 tries to twist upward while a tensile and compressive force is applied to the first connecting arm 11, and the other The second connecting arm 13 tends to twist downward and tries to rotate as a whole.

  In particular, when detecting the acceleration in the X-axis direction and the Y-axis direction, the acceleration in the Y-axis direction is detected by rotating the weight portion 2 around the X axis around the first connecting arm 11, The acceleration is detected when the weight portion 2 rotates around the Y axis with the second connecting arm 13 as an axis, and can be detected independently, so that a decrease in detection can be suppressed.

(Embodiment 2)
9 is an exploded perspective view of the detection element of the composite sensor according to the second embodiment of the present invention, FIG. 10 is a cross-sectional view taken along line AA in FIG. 9, and FIG. 11 is a cross-sectional view taken along line BB in FIG.

  The detection element of the composite sensor according to the second embodiment of the present invention is obtained by improving the second connection arm 13 in the detection element of the composite sensor according to the first embodiment.

  9-11, the 1st arm 8 is a T-shaped orthogonal arm which made the 1st connection arm 11 orthogonal to the 2nd connection arm 13, Comprising: One end of this 1st connection arm 11 is a support part. 12, and is connected to the weight portion 2 via the second arm 10, and the other end of the first connection arm 11 is connected to a second connection arm 13 that is orthogonal to the second connection arm 13. Are connected to the frame body portion 4. At this time, both end portions of the second connection arm 13 extend in the same direction as the first connection arm 11 and are connected to the frame body portion 4. The detection of angular velocity and the detection of acceleration are the same as in the first embodiment. With the above configuration, the same effect as that of the composite sensor in the first embodiment can be obtained in the second embodiment.

  Since the inertial force sensor according to the present invention can improve the detection sensitivity, it can be applied to various electronic devices.

The disassembled perspective view of the detection element of the composite sensor in the 1st Embodiment of this invention AA sectional view of FIG. BB sectional view of FIG. Operation state diagram of the detection element during angular velocity detection AA cross-sectional view when the counter substrate is placed Operation state diagram of the detection element when detecting acceleration in the X-axis direction BB cross section when counter substrate is placed Operation state diagram of the detection element when detecting acceleration in the Y-axis direction The disassembled perspective view of the detection element of the composite sensor in the 2nd Embodiment of this invention AA sectional view of FIG. BB sectional view of FIG. Plan view of conventional detector AA sectional view of FIG. BB sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Detection element 2 Weight part 4 Frame body part 6 Opposite substrate 8 1st arm 10 2nd arm 11 1st connection arm 12 Support part 13 2nd connection arm 14 1st counter electrode 16 2nd counter electrode 18 3rd counter electrode 20 Fourth counter electrode 22 Drive electrode 24 Sense electrode 26 First sense electrode 28 Second sense electrode

Claims (6)

A detection element having an acceleration detection unit;
The detecting element connects a weight part via a connecting part, a frame body part in which the weight part is disposed inward, a counter substrate opposed to the weight part, and each of the weight part and the counter substrate And the acceleration detecting unit detects an acceleration by detecting a change in capacitance between the counter electrode arranged on each opposing surface of the weight part and the opposing substrate. And
The connecting portion is an orthogonal arm in which a first connecting arm is orthogonal to a second connecting arm, and connects one end of the first connecting arm to the weight portion and both ends of the second arm to the frame body. An inertial force sensor coupled to a portion, wherein the thickness of the first coupling arm and the thickness of the second coupling arm are smaller than the thickness of the weight portion. 2. The inertial force sensor according to claim 1, wherein both end portions of the second connection arm extend in the same direction as the first connection arm and are connected to the frame body portion. 2. The inertial force sensor according to claim 1, wherein both end portions of the second connecting arm extend in a direction orthogonal to the first connecting arm and are connected to the frame body portion. The inertial force sensor according to claim 1, wherein the detection element has a symmetrical shape. An angular velocity detection unit is provided in the detection element,
The detection element includes two orthogonal arms formed by connecting the first arm to the second arm in the orthogonal direction, and a support portion supporting the two first arms, and the first arm is the first arm. The weight portion is connected to the distal end portion of the second arm, and the angular velocity detection portion drives and vibrates the weight portion to detect a change in the state of the detection element due to the Coriolis force. The inertial force sensor according to claim 1, wherein the angular velocity is detected. 6. The inertial force sensor according to claim 5, wherein the angular velocity is detected by bending the second arm until it opposes and detecting a state change of the second arm.

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