JP2009222476A - Compound sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inertia force sensor attaining reduction in its mounting area and its size in detecting angular velocity and acceleration. <P>SOLUTION: In mutually orthogonal X, Y, Z axes, a firs arm 4 is disposed in the X axis direction and a second arm 6 is disposed in the Y axis direction, and an angular velocity detection part detects an angular velocity, based on the change in the state of a detection device 2 caused by the angular velocity, by vibrating the second arm 6 to the direction of the x axis and the acceleration detection part detects an acceleration based on the change in the state of the detection device 2 caused by the acceleration. An opposite part 21 is can freely move in any of the axis direction caused by an acceleration to any of the X, Y, Z-axis directions. The compound sensor is configured to detect the acceleration based on an electrostatic capacitance between the opposing electrodes 22 changing by the movement of the opposite part 21 caused be the acceleration. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a composite sensor that detects angular velocity and acceleration used in various electronic devices such as attitude control and navigation of a moving body such as an aircraft, an automobile, a robot, a ship, and a vehicle.

  Hereinafter, a conventional composite sensor will be described.

  Conventionally, when detecting angular velocity and acceleration, a dedicated angular velocity sensor is used to detect the angular velocity, and a dedicated acceleration sensor is used to detect the acceleration.

Therefore, when various angular velocity and acceleration are detected in various electronic devices, a plurality of angular velocity sensors and acceleration sensors are mounted on the mounting boards of the various electronic devices.

In general, an angular velocity sensor vibrates detection elements of various shapes such as a sound shape, an H shape, a T shape, and the like, and detects an angular velocity by electrically detecting a change in the state of the detection element accompanying the generation of Coriolis force. The acceleration sensor detects the acceleration by detecting the change in the state of the detection element associated with the acceleration.

Such an angular velocity sensor or an acceleration sensor is used for 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.

For example, Patent Document 1 and Patent Document 2 are known as prior art document information related to the invention of this application.
JP 2001-208546 A JP 2001-74767 A

In the above configuration, since the angular velocity sensor and the acceleration sensor are mounted on the mounting substrate in correspondence with the detection axis of the angular velocity and acceleration to be detected, it is necessary to secure a mounting area, and there is a problem that the size cannot be reduced. It was.

An object of the present invention is to solve the above-mentioned problems and to provide a composite sensor that is reduced in size by reducing the mounting area when detecting angular velocity and acceleration.

  In order to achieve the above object, in particular, the present invention provides a detection element comprising a first arm and a second arm that are formed by connecting a first arm and a second arm in a perpendicular direction, and a first support that supports one end of the first arm. An X-axis, a Y-axis, and a Z-axis perpendicular to each other, and a counter electrode disposed on a counter surface of each of the second arm and the counter section. One arm is arranged in the X-axis direction, the second arm is arranged in the Y-axis direction, and the angular velocity detector vibrates the second arm in the X-axis direction, and the state change of the detection element due to the angular velocity The acceleration detection unit detects an acceleration based on a change in capacitance between the second arm and the counter electrode of the counter unit due to the acceleration, and the counter unit is X Acceleration in the axial direction of any of the Y, Z, and Z axes A freely movable in either axial direction In to a configuration for detecting acceleration based on electrostatic capacitance between the counter electrode varies by the movable of the facing portion caused by the acceleration.

  With the above configuration, since the angular velocity detection unit for detecting the angular velocity and the acceleration detection unit for detecting the acceleration are formed in one detection element, the mounting area can be reduced and the size can be reduced.

  In addition, the second arm and a counter electrode disposed on each of the opposing surfaces of the counter part, the counter part is in any axial direction due to acceleration in any of the X, Y, and Z axis directions Since the acceleration is detected based on the capacitance between the opposed electrodes that changes due to the movement of the opposed portion caused by the acceleration, the acceleration detection sensitivity can be improved.

  That is, the opposing portion that faces the second arm does not function for detecting the angular velocity, but only functions for detecting the acceleration. Therefore, when the opposing portion is movable, the configuration in consideration of the detection of the angular velocity is adopted. In particular, it is possible to ensure the degree of freedom of design of the first connecting part and the second connecting part. For example, since the opposing portion can be configured to be very movable, when the opposing portion moves in any of the X, Y, and Z axis directions due to acceleration, the capacitance change increases and the acceleration Detection sensitivity can be improved.

  Furthermore, the second arm connected in a direction orthogonal to the first arm is vibrated in the X-axis direction, and it is necessary to adopt a configuration that considers the detection of acceleration when detecting the angular velocity based on the state change of the detection element caused by the angular velocity. And there is no design freedom. For example, since the thickness of the first arm and the second arm can be made equal to suppress the bending in the Z-axis direction, when the state of the first arm or the second arm changes due to the angular velocity, the Z A change in the state in the axial direction is suppressed, and deterioration of the angular velocity detection accuracy can be suppressed.

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

  The composite sensor in one embodiment of the present invention includes a detection element 2 having an angular velocity detection unit and an acceleration detection unit.

  In FIG. 1 and FIG. 3, the detection element 2 has two orthogonal arms formed by connecting the first arm 4 to the second arm 6 in the orthogonal direction, and one end of the two first arms 4 is supported by the support portion 8. The other ends of the two first arms 4 are connected to the rectangular frame body portion 12. The first arm 4, the second arm 6, and the support portion 8 are all shaped to have the same thickness, and the second arm 6 bends in a U shape until it faces the second arm 6 itself. The weight portion 14 is connected to the tip portion. The first arm 4 and the support portion 8 are arranged on substantially the same straight line, and the first arm 4 and the second arm 6 are arranged symmetrically with respect to the center of the detection element 2.

  When the first arm 4 is arranged in the X-axis direction and the second arm 6 is arranged in the Y-axis direction on the X-axis, Y-axis, and Z-axis orthogonal to each other, the second arms facing each other on the positive side of the Y-axis 6 includes a first drive electrode 16 and a second drive electrode 18 that drive and vibrate the two weight portions 14 on the positive side of the Y axis in opposite directions, and a second arm facing each other on the negative side of the Y axis. 6 includes a sensing electrode 20 that senses the strain of the second arm 6. The first drive electrode 16, the second drive electrode 18, and the sensing electrode 20 may be arranged symmetrically.

  The first and second drive electrodes 16 and 18 and the sensing electrode 20 are formed of an upper electrode and a lower electrode with a piezoelectric layer interposed therebetween.

  In FIG. 1 and FIG. 2, two opposing portions 21 arranged on the positive side of the Z axis are provided so as to face the first and second arms 4 and 6 and the weight portion 14. The facing portion 21 is a weight portion, and the two facing portions 21 are supported by the second support portion 25 via the first connecting portion 23, and the second supporting portion 25 is supported via the second connecting portion 27. Is fixed by a fixing portion 29. The fixing portion 29 has a frame shape, the first connecting portion 23 and the second connecting portion 27 have an arm shape, and the first connecting portion 23 and the second connecting portion 27 are arranged orthogonal to each other, and the second connecting portion 27 The thickness is made thinner than the thickness of the first connecting portion 23. As shown in FIG. 2, the fixing portion 29 is formed on the frame body portion 12 via the bump portion 31, and the opposing portion 21 and the first and second arms 4, 6 depend on the thickness of the bump portion 31. The second support portion 25 is held hollow by the second connecting portion 27 so that the weight portion 14 does not contact each other. Further, in the present invention, the first and second arms 4 and 6, the weight portion 14 and the facing portion 21 are held hollow so as not to contact each other by the bump portion 31, but in the bump portion 31, by plating or the like, The same effect can be obtained with a convex holding portion formed on the frame body 12. A counter electrode 22 is disposed on each of the facing surfaces of the counter portion 21 and the weight portion 14, and the capacitance (H) between the weight portion 14 and the counter portion 21 of the second arm 6 is changed by the counter electrode 22. In order to detect, it is made to approach.

  Furthermore, the first counter substrate 24 is disposed on the positive side of the Z axis so as to face the counter portion 21, the second support portion 25, the first and second connecting portions 23 and 27, and the first and second arms 4. 6, the second counter substrate 26 is disposed on the negative side of the Z axis so as to face the weight portion 14. The first counter substrate 24 is provided with a first recess 33 on a surface facing the counter portion 21 so as not to contact the counter portion 21, and the second counter substrate 26 is opposed to the weight portion 14 so as not to contact the weight portion 14. A second recess 35 is provided in The first counter substrate 24 is stacked on the fixed portion 29, and the frame body 12 is stacked on the second counter substrate 26.

  The first concave portion 33 and the second concave portion 35 are used as stoppers so that the second connecting portion 27 is not broken by the inertial force due to the acceleration when a large acceleration outside the measurement range is applied to the element portion 2. Has depth.

  Next, detection of angular velocity will be described.

  FIG. 4 is an enlarged perspective view showing a driving vibration state of the portion 2A in FIG.

  When the first arm 4 is arranged in the X-axis direction and the second arm 6 is arranged in the Y-axis direction as shown in FIG. 4 in the X-axis, Y-axis, and Z-axis orthogonal to each other, the first and second An AC voltage having a resonance frequency is applied to the drive electrodes 16 and 18 to drive and vibrate the second arm 6 starting from the second arm 6 on which the first and second drive electrodes 16 and 18 are arranged. The part 14 is also driven to vibrate in the direction facing the second arm 6 (the direction of the driving vibration indicated by the solid arrow and the dotted arrow). The AC voltage applied to the first drive electrode 16 and the AC voltage applied to the second drive electrode 18 are applied in opposite phases, and the width of each second arm 6 on the positive side of the Y axis increases. They are vibrated in opposite directions so as to narrow. In synchronization with this, the two second arms 6 arranged on the negative side of the Y axis also vibrate in opposite directions, and vibrate symmetrically around the Y axis. That is, all of the four second arms 6 and the four weight portions 14 are synchronously driven and vibrated in the opposing direction (drive vibration direction) of the second arm 6, and the drive vibration direction in the detection element 2 is the X-axis direction. It has become.

  A specific angular velocity detection will be described.

  In such a detection element 2, for example, when an angular velocity is generated clockwise around the Z axis, the driving vibration direction with respect to the weight portion 14 is synchronized with the driving vibration of the weight portion 14 as shown in FIG. Since the Coriolis force is generated in the direction orthogonal to the direction (Coriolis direction indicated by the solid line arrow and the dotted line arrow), the second arm 6 is distorted due to the clockwise angular velocity of the Z axis. At this time, the Coriolis direction of the detection element 2 is the Y-axis direction. When the Coriolis force is generated, each sensing electrode 20 disposed on the second arm 6 senses the distortion of the second arm 6, and the direction in which the Coriolis force is generated can be determined by the polarity of the sensing electrode 20. For example, two sensing electrodes 20 are arranged on the inside and the outside of the second arm 6, respectively, and the difference between the strain on the inside and the outside of the second arm 6 is sensed to determine the direction of Coriolis force generation. Good. Since the strain elongation rate inside the second arm 6 is different from the strain elongation rate outside, the difference in strain can be sensed. Similarly, when the counterclockwise angular velocity of the Z axis is generated, the distortion of the second arm 6 may be sensed. As described above, the angular velocity can be detected by sensing the distortion of the second arm 6 caused by the angular velocity.

  Next, detection of acceleration will be described.

  When the first arm 4 is arranged in the X-axis direction and the second arm 6 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 Z-axis direction. As shown in FIG. 2, the two opposing portions 21 are about to be displaced in the Z-axis direction. At this time, the facing distance (H) between the facing portion 21 and the weight portion 14 is increased, and the capacitance between all the facing electrodes 22 is decreased.

  When acceleration occurs in the X-axis direction, as shown in FIG. 6, the opposing distance (H1) between the opposing portion 21 and the weight portion 14 on the positive side of the X-axis is generated while the second connecting portion 27 is distorted. In the opposing distance (H2) between the opposing part 21 and the weight part 14 on the negative side of the X axis, if the opposing distance (H1) decreases, the opposing distance (H2) increases. That is, the capacitance between one counter electrode 22 increases and the capacitance between the other counter electrode 22 decreases.

  When acceleration occurs in the Y-axis direction, although not shown, the facing distance between the facing portion 21 and the weight portion 14 on the positive side of the Y-axis, the facing portion 21 and the Y-axis are not shown. In the facing distance from the negative weight portion 14, if one facing distance increases, the other facing distance decreases. In other words, the capacitance between the counter electrodes 22 also changes so that the change in the capacitance of the other electrode becomes smaller if one of them becomes larger.

  Thus, the acceleration can be detected by sensing the change in the capacitance between the counter electrodes 22 caused by the acceleration. In particular, since the facing distance (H) between the two facing portions 21 and the four weight portions 14 changes depending on the direction in which the acceleration occurs, the direction of acceleration can be detected simultaneously by sensing this.

  With the above configuration, the angular velocity detection unit for detecting the angular velocity and the acceleration detection unit for detecting the acceleration are formed in one detection element 2, so that the mounting area can be reduced and the size can be reduced.

  Moreover, it has the 2nd arm 6 and the counter electrode 22 arrange | positioned on each opposing surface of the opposing part 21, and the opposing part 21 originates in the acceleration of any axial direction of a X, Y, Z-axis direction, and any Since the acceleration is detected based on the capacitance between the opposing electrodes 22 that is movable in the axial direction and changes due to the movement of the opposing portion 21 caused by the acceleration, the acceleration detection sensitivity can be improved.

  That is, the facing portion 21 facing the second arm 6 does not function for detecting the angular velocity, but functions only for detecting the acceleration, so that the detection of the angular velocity is considered when the facing portion 21 is movable. In particular, the degree of freedom in designing the first connecting portion 23 and the second connecting portion 27 can be ensured. For example, as in the embodiment of the present invention, the opposing portion 21 is a weight portion, the two opposing portions 21 are supported by the second supporting portion 25 via the first connecting portion 23, and the second connecting portion 27 is The second support portion 25 is fixed by the fixing portion 29, the fixing portion 29 is formed into a frame shape, the first connecting portion 23 and the second connecting portion 27 are formed in an arm shape, and the first connecting portion 23 and the second connecting portion When the second connecting portion 27 is arranged so as to be orthogonal to the connecting portion 27 and the thickness of the second connecting portion 27 is smaller than the thickness of the first connecting portion 23, the facing portion 21 is movable in the X axis direction, the Y axis direction, and the Z axis direction. It becomes easy to do.

  In FIG. 1, when the facing portion 21 moves in the X-axis direction, one second connecting portion 27 is easily distorted downward and the other second connecting portion 27 is easily distorted upward. The opposing portion 21 is inclined and the capacitance between the opposing electrodes 22 easily changes. When the facing portion 21 is movable in the Y-axis direction, the second connecting portion 27 is easily twisted, and the facing portion 21 is inclined in the Y-axis direction, so that the capacitance between the facing electrodes 22 easily changes. When the facing portion 21 moves in the Z-axis direction, the second connecting portion 27 is pulled in the Z-axis direction, and the position of the facing portion 21 fluctuates in the Z-axis direction so that the capacitance between the facing electrodes 22 is easy. To change. In particular, since the thickness of the second connecting portion 27 is smaller than the thickness of the first connecting portion 23, the second connecting portion 27 is easily distorted, twisted or pulled easily.

  In this way, since the facing portion 21 can be configured to be very movable, when the facing portion 21 moves in any of the X, Y, and Z axis directions due to acceleration, a change in capacitance occurs. It becomes large and the detection sensitivity of acceleration can be improved.

  In addition, the second arm 6 connected to the first arm 4 in the orthogonal direction is vibrated in the X-axis direction, and the detection of acceleration is taken into account when detecting the angular velocity based on the state change of the detection element 2 caused by the angular velocity. The degree of freedom in design can be secured. For example, when the thicknesses of the first arm 4 and the second arm 6 are made equal as in the embodiment of the present invention, the first arm 4 and the second arm 6 are driven when the weight portion 14 of the second arm 6 vibrates. The two arms 6 are difficult to bend in the Z-axis direction.

  In FIG. 4, when the weight portion 14 of the second arm 6 is driven and vibrated in the X-axis direction, the weight portion 14 is subjected to Coriolis force in the Y-axis direction due to the angular velocity, but the arm 6 is distorted. Since the thickness of the arm 6 is the same as that of the first arm 4, it is difficult to bend in the Z-axis direction when driving vibration or receiving Coriolis force, and the loss of sensitivity can be suppressed by the amount of bending in the Z-axis direction.

  Thus, since it can be set as the structure which suppresses the bending to a Z-axis direction, when the state of the 1st arm 4 or the 2nd arm 6 changes according to an angular velocity, the change of the state to a Z-axis direction is suppressed. Detection sensitivity can be improved.

  In addition to the embodiment of the present invention, for example, the counter electrode 22 is arranged on each counter surface of the first counter substrate 24 that opposes the counter unit 21, and the acceleration detection unit counters the acceleration due to the acceleration. The capacitance change between the counter electrodes 22 disposed on the facing surfaces of the facing portion 21 and the weight portion 14 that change as the portion 21 moves, and the facing portions 21 and the first facing substrate 24 are disposed on the facing surfaces. The acceleration may be detected based on the capacitance change between the counter electrodes 22.

  Further, the configuration of the detection element 2 is not limited to the embodiment of the present invention, and may be other configurations.

  The inertial force sensor according to the present invention can be applied to various electronic devices because the mounting area can be reduced and the size can be reduced when detecting angular velocity and acceleration.

The disassembled perspective view of the detection element of the composite sensor in one embodiment of this invention AA sectional view of FIG. Enlarged perspective view of part 2A in FIG. FIG. 2 is an enlarged perspective view showing a driving vibration state of the portion 2A in FIG. AA sectional view of FIG. 1 when acceleration in the Z-axis direction occurs AA cross-sectional view of FIG. 1 when acceleration in the X-axis direction occurs

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Detection element 4 1st arm 6 2nd arm 8 Support part 12 Frame part 14 Weight part 16 1st drive electrode 18 2nd drive electrode 20 Sensing electrode 21 Opposing part 22 Opposing electrode 23 1st connection part 24 1st opposing board | substrate 25 second support portion 26 second counter substrate 27 second connecting portion 29 fixing portion 31 bump portion 33 first recess 35 second recess

Claims (6)

A detection element having an acceleration detection unit and an angular velocity detection unit;
The detection element includes an orthogonal arm formed by connecting a first arm and a second arm in an orthogonal direction, a first support portion that supports one end of the first arm, and a facing portion that faces the second arm. And a counter electrode disposed on each of the opposing surfaces of the second arm and the opposing portion,
In the X, Y, and Z axes orthogonal to each other, the first arm is disposed in the X-axis direction, the second arm is disposed in the Y-axis direction,
The angular velocity detection unit vibrates the second arm in the X-axis direction and detects an angular velocity based on a state change of the detection element caused by the angular velocity,
The acceleration detection unit detects acceleration based on a capacitance change between the second arm and the counter electrode of the counter unit due to the acceleration,
The opposing portion is movable in any axial direction due to acceleration in any axial direction of the X, Y, and Z axes, and the opposing electrode changes depending on the movement of the opposing portion due to acceleration A composite sensor that detects acceleration based on the capacitance between the two. The composite sensor according to claim 1, wherein the first and second arms have the same thickness. The composite sensor according to claim 1, wherein a plurality of orthogonal arms are provided, and the detection element is symmetrical. The composite sensor according to claim 1, wherein a tip portion of the second arm and the facing portion are weight portions. A plurality of the facing portions are provided, and the second supporting portion that supports the plurality of facing portions via the first connecting portion and the fixing portion that holds the second supporting portion hollow via the second connecting portion are provided. The composite sensor according to claim 1, wherein the first connection portion and the second connection portion are arranged orthogonal to each other, and the thickness of the second connection portion is smaller than the thickness of the first connection portion. A counter substrate facing the counter portion is disposed, a second counter electrode is disposed on each of the counter surfaces of the counter portion and the counter substrate, and the acceleration detection unit changes depending on the movement of the counter unit due to acceleration. The composite sensor according to claim 1, wherein acceleration is detected based on a capacitance between the opposing electrodes and a capacitance change between the second opposing electrodes.

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