JP4774733B2 - Compound sensor - Google Patents

Description

  The present invention relates to a composite sensor that combines an angular velocity sensor and an acceleration sensor used in various electronic devices such as attitude control and navigation of moving bodies such as aircraft, automobiles, robots, ships, and vehicles.

  Hereinafter, a conventional composite sensor will be described.

  A conventional composite sensor is a composite sensor in which an angular velocity sensor and an acceleration sensor are each mounted on a mounting substrate.

  Conventional angular velocity sensors, for example, vibrate vibrators of various shapes such as sound shape, H shape, T shape, etc., and electrically detect the distortion of the vibrator accompanying the generation of Coriolis force to calculate the angular velocity To do.

  The conventional acceleration sensor has a weight portion, and calculates the acceleration by comparing and detecting the movement of the weight portion due to the acceleration before the movement.

  Such angular velocity sensors and acceleration sensors are used in navigation devices and vehicle control devices mounted on vehicles.

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

  The composite sensor having the above-described configuration is obtained by mounting an angular velocity sensor and an acceleration sensor on each mounting board, and it is necessary to secure a mounting area for the angular velocity sensor and a mounting area for the acceleration sensor, so that the mounting board can be reduced in size. Had the problem of not.

  In order to solve the above problems, the present invention does not require the mounting area of the angular velocity sensor and the mounting area of the acceleration sensor, but reduces the mounting area by combining the angular velocity sensor and the acceleration sensor, thereby reducing the size of the mounting board. It aims at providing the compound sensor which aimed at.

In order to solve the above problems, the present invention provides a rectangular frame-shaped fixed base having four corners, a central base connected to four corners of the frame-shaped fixed base by four connecting portions, An X-axis comprising two angular velocity sensors symmetrically arranged in a uniaxial direction around the base and two acceleration sensors symmetrically arranged in the direction of the other axis different from the angular velocity sensor around the central base. Two angular velocity sensors symmetrically arranged in the Y- axis direction around the central base in the Y-axis and Z-axis, and two acceleration sensors symmetrically arranged in the X- axis direction around the central base, Has a T shape in which one end of the first arm arranged in the Y-axis direction is connected to the central base, the other end is connected to the center of the second arm, and the second arm is arranged in the X-axis direction. , the first a A first detection positive electrodes and the first detecting negative electrode disposed beam, a first piezoelectric element and the first driving positive electrode and the first driving negative electrodes disposed on the second arm, the acceleration sensor, The angular velocity sensor has a configuration in which the weight portion and the central base portion are connected by a second piezoelectric element including a second drive positive electrode, a second drive negative electrode, a second detection positive electrode, and a second detection negative electrode. The second arm vibrates in the Y-axis direction, and in the acceleration sensor, the second piezoelectric element vibrates in the Z-axis direction .

As described above, the present invention has a rectangular frame-shaped fixed base having four corners, a center base connected to the four corners of the frame-shaped fixed base by four connecting portions, and the center base. , Two angular velocity sensors arranged symmetrically in one axis direction, and two acceleration sensors arranged symmetrically in the direction of the other axis different from the angular velocity sensor around the central base, and an X axis and a Y axis substantially orthogonal to each other in the Z-axis, around the central base portion, and two angular velocity sensors symmetrically arranged in the Y-axis direction, around the central base comprises two acceleration sensors symmetrical arrangement in the X-axis direction, the angular velocity sensor, the Y-axis one end of the first arm disposed in the direction connected to the central base portion, connecting the other end to the middle of the second arm, the second arm with a T shape arranged in the X-axis direction, the first arm First test A positive electrode and a first detecting negative electrodes are arranged, a first piezoelectric element and the first driving positive electrode and the first driving negative electrodes disposed on the second arm, the acceleration sensor, the weight portion and a central base portion , A second drive positive electrode, a second drive negative electrode, a second detection positive electrode, and a second piezoelectric element having a second detection negative electrode, and the second arm is connected to the angular velocity sensor. Since the second piezoelectric element vibrates in the Y-axis direction and the second piezoelectric element vibrates in the Z-axis direction in the acceleration sensor, the angular velocity sensor and the acceleration sensor are provided in the frame-shaped fixed base. The mounting substrate can be reduced in size.

  Further, since the two angular velocity sensors are symmetrically arranged in the uniaxial direction with the center base as the center, the mutual vibrations can be canceled and absorbed, and as a result, the accuracy can be improved. Furthermore, since the two acceleration sensors are symmetrically arranged in the uniaxial direction with the central base as the center, the mutual vibrations can be canceled and absorbed, and as a result, the accuracy can be improved. Furthermore, these two angular velocity sensors and two acceleration sensors are arranged in different axial directions in a rectangular frame-shaped fixed base having four corners. Interference can be suppressed, and as a result, the detection accuracy of both can be improved.

  That is, the angular velocity sensor and the acceleration sensor can be combined, and the mounting area can be reduced and the mounting substrate can be downsized.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a premise example of the present invention will be described with reference to FIGS.

  The composite sensor shown in FIG. 1 is a composite sensor having an angular velocity sensor and an acceleration sensor, and is disposed inside the frame-shaped fixed base 1 and inside the frame-shaped fixed base 1, and connected to the frame-shaped fixed base 1. A central base 3 connected via the first base, a first piezoelectric element 4 connected to the central base 3, a weight 6 disposed around the central base 3, and a second connected to the weight 6 and the central base 3. A vibrator 10 having a piezoelectric element 8 is provided, and a frame-like fixed base 1 of the vibrator 10 is attached and supported on a substrate 11 on which a signal processing circuit is mounted. The central base 3 may be in contact with the substrate 11 or non-contact.

  The first piezoelectric element 4 and the second piezoelectric element 8 are driven to vibrate, and the angular velocity sensor calculates the angular velocity by detecting the bending vibration of the first piezoelectric element 4 that changes due to the Coriolis force, and serves as an acceleration sensor. Can detect the driving vibration of the second piezoelectric element 8 that changes due to the movement of the weight 6 and calculate the acceleration.

  The connecting portion 2 that connects the frame-shaped fixed base 1 and the central base 3 is substantially the same as the width of the frame-shaped fixed base 1 and forms a vibration absorbing portion. The vibration absorbing portion plays a role of a damper function (vibration absorbing function), and the vibration absorbing portion may be a simple linear object, but may be provided with a mesh, a groove, a concave portion, or the like. In particular, the frame-like fixed base 1 is preferably formed in a square shape having four corners, and the four corners and the central base 3 are connected by the four connecting portions 2.

  The first piezoelectric element 4 has a T shape having a first arm 12 and a second arm 14 that are connected substantially orthogonally to each other, and connects the first arm 12 to the central base 3 and is substantially orthogonal to each other. The first arm 12 is arranged in the Y-axis direction on the axis, the Y-axis, and the Z-axis. The weight portion 6 is E-shaped, and a part of the weight portion 6 is used as a connecting portion 16 for connecting the central base portion 3, and the weight portion 6 and the central base portion 3 are connected via the connecting portion 16 of the weight portion 6. It is connected. Two second piezoelectric elements 8 are arranged on both sides of the connecting part 16 of the weight part 6, and both the weight part 6 and the second piezoelectric element 8 are arranged in the Y-axis direction.

  2 to 4, the first piezoelectric element 4 is provided with a drive electrode for applying drive vibration and a detection electrode for detecting flexural vibration caused by angular velocity. The first arm 12 is provided with the drive positive electrode 20 and the drive negative electrode 18 so that the drive negative electrode 18 is sandwiched between the two drive positive electrodes 20, and the drive positive electrode 20 and the drive negative electrode 18 are sandwiched therebetween. As described above, the detection positive electrode 22 and the detection negative electrode 23 are arranged. On the second arm 14, the driving negative electrode 18 arranged on the first arm 12 is arranged in a T shape, and the driving positive electrode 20 is arranged in an L shape. Of the two drive positive electrodes 20, one drive positive electrode 20 may be used as a monitor positive electrode for monitoring drive vibration, and the drive negative electrode 18 may be shared as a monitor negative electrode.

  In the first piezoelectric element 4, a Pt lower electrode 28 is formed on a silicon plate 26 by high frequency sputtering, and a PZT piezoelectric body 30 is formed on the lower electrode 28 by high frequency sputtering. The upper electrode 32 is formed by Au evaporation. When an alternating voltage having a resonance frequency at which silicon resonates is applied to the drive positive electrode 20 and the drive negative electrode 18 sandwiching the PZT piezoelectric body 30 by the lower electrode 28 and the upper electrode 32, the drive positive electrode 20 side and the drive negative electrode On each of the 18th side, the PZT piezoelectric body 30 expands and contracts, and the second arm 14 vibrates.

  When the silicon plate 26 receives strain (bending vibration) due to the Coriolis force due to the angular velocity, a charge is generated in the PZT piezoelectric body 30, and this is detected by the detection positive electrode 22 and the detection negative electrode 23. To detect.

  In FIG. 5, the thickness of the weight portion 6 is greater than the thickness of the second piezoelectric element 8. Similarly to the first piezoelectric element 4, the second piezoelectric element 8 is formed by forming a Pt lower electrode 28 on a silicon plate 26 by high frequency sputtering, and a PZT piezoelectric body on the lower electrode 28 by high frequency sputtering. 30 is formed, and an upper electrode 32 is formed on the upper portion by Au evaporation. When an alternating voltage having a resonance frequency at which silicon resonates is applied to the drive positive electrode 20 and the drive negative electrode 18 sandwiching the PZT piezoelectric body 30 by the lower electrode 28 and the upper electrode 32, the drive positive electrode 20 side and the drive negative electrode On each of the 18th side, the PZT piezoelectric body 30 expands and contracts, and the second piezoelectric element 8 is driven to vibrate.

  The frame-like fixed base 1, the central base 3, the connection 2, the first piezoelectric element 4, the second piezoelectric element 8, and the weight 6 are preferably formed integrally from the silicon plate 26.

  Next, the drive vibration and operation state of the first piezoelectric element 4 and the second piezoelectric element 8 will be described.

  As shown in FIG. 6, the first piezoelectric element 4 and the second piezoelectric element 8 drive and vibrate each other in the direction of the arrow. The first piezoelectric element 4 is driven to vibrate so that both ends of the second arm 14 are alternately repeated in the (+ Y) direction and the (−Y) direction of the Y axis, and the second piezoelectric element 8 is Drive vibration is repeated so as to alternate between the (+ Z) direction and the (−Z) direction.

  With this driving vibration, the angular velocity and acceleration are calculated as follows.

  The angular velocity sensor detects the bending vibration of the first piezoelectric element 4 that changes due to the Coriolis force, and calculates the angular velocity. The angular velocity around the X axis is the first in the Z axis direction as shown in FIG. The bending vibration of one arm 12 is detected and calculated, and the angular velocity around the Z-axis is calculated by detecting bending vibration of the first arm 12 in the X-axis direction as shown in FIG. In FIG. 7, the second arm 14 bends and vibrates so that the whole of the second arm 14 alternately repeats in the (+ Z) direction and the (−Z) direction of the Z axis. Accordingly, the first arm 12 also follows the (+ Z) direction of the Z axis. And bending vibration so as to repeat alternately in the (−Z) direction. In FIG. 8, the second arm 14 bends and vibrates so that the entirety of the second arm 14 alternately repeats in the (+ X) direction and the (−X) direction of the X axis, and accordingly, the first arm 12 also follows the (+ X) direction of the X axis. And bending vibration so as to repeat alternately in the (−X) direction.

  The acceleration sensor detects the driving vibration of the second piezoelectric element 8 that changes due to the movement of the weight 6 and calculates the acceleration.

  As shown in FIG. 9, for example, when acceleration occurs in the (+ X) direction side of the X axis (the weight part 6 tries to move in the (−X) direction of the X axis), the (−X) of the weight part 6 Stress is generated at the end on the direction side on the (+ Y) direction side of the Y axis, and at the end on the (+ X) direction side of the weight portion 6 with respect to the (−Y) direction side of the Y axis. Then, different tensions are applied to the two second piezoelectric elements 8 connecting the weight part 6 and the fixed base part according to the movement of the weight part 6. That is, the tension is applied so that the second piezoelectric element 8 on the (−X) direction side of the weight portion 6 contracts in the Y-axis direction, and the second piezoelectric element 8 on the (+ X) direction side of the weight portion 6 extends in the Y-axis direction. So that tension is applied.

  At this time, for example, the resonance frequency (natural value) of the natural vibration of the two second piezoelectric elements 8 changes compared to the state before the weight portion 6 is moved (the drive vibration frequency of one of the second piezoelectric elements 8 is high). Therefore, the drive vibration frequency of the other second piezoelectric element 8 is lowered), and this may be detected. That is, the lower electrode 28 and the upper electrode 32 serve as a drive positive electrode, a drive negative electrode, a detection positive electrode, and a detection negative electrode.

  With the above configuration, the frame-shaped fixed base 1 is disposed inside the frame-shaped fixed base 1, and the central base 3 is connected to the frame-shaped fixed base 1 via the connection portion 2. The first piezoelectric element 4, the weight part 6 arranged around the central base part 3, and the second piezoelectric element 8 connecting the weight part 6 and the central base part 3, Since the two piezoelectric elements 8 are driven to vibrate, the angular velocity sensor can calculate the angular velocity by detecting the bending vibration of the first piezoelectric element 4, and the acceleration sensor changes due to the movement of the weight portion 6. The acceleration can be calculated by detecting the driving vibration of the second piezoelectric element 8.

  That is, the angular velocity sensor and the acceleration sensor can be combined, and the mounting area can be reduced and the mounting substrate 11 can be downsized.

  In particular, the connecting portion 2 that connects the frame-shaped fixed base 1 and the center base 3 is substantially equal to the width of the frame-shaped fixed base 1 and forms a vibration absorbing portion. Therefore, the vibration absorbing portion has a damper function (vibration absorbing). Even if an impact, noise, or the like is applied to the composite sensor, the impact or noise can be absorbed, and destruction of the vibrator 10 can be suppressed or detection accuracy can be improved. The vibration absorbing portion may be a simple linear object, but may be provided with a mesh, a groove, a concave portion, or the like. In particular, the frame-like fixed base 1 is preferably formed in a square shape having four corners, and the four corners and the central base 3 are connected by the four connecting portions 2.

  The first piezoelectric element 4 has a T shape having a first arm 12 and a second arm 14 that are connected substantially orthogonally to each other, and the first arm 12 is arranged in the Y-axis direction and is second in the Y-axis direction. The arm 14 is driven to vibrate, the angular velocity around the Z-axis is calculated by detecting the bending vibration of the first arm 12 in the X-axis direction, and the angular velocity around the X-axis is calculated by bending the first arm 12 in the Z-axis direction. The weight portion 6 and the two second piezoelectric elements 8 are arranged in the Y-axis direction and the second piezoelectric element 8 is driven to vibrate, and the acceleration in the X-axis direction is the weight portion in the X-axis direction. 6, the driving vibration of the second piezoelectric element 8 that changes due to the movement of the second piezoelectric element 8 is detected and calculated. Therefore, the first piezoelectric element 4 and the second piezoelectric element 8 can be used face down, and the height can be reduced.

  The angular velocity sensor increases the Coriolis force when the angular velocity occurs by increasing the end of the second arm 14 of the first piezoelectric element 4 or connecting the arm weight, thereby improving detection accuracy. In addition, the resonance frequency can be reduced.

  The acceleration sensor suppresses the movement of the weight portion 6 in the Z-axis direction by making the thickness of the connecting portion 16 of the weight portion 6 thicker than the thickness of the second piezoelectric element 8, and is affected by the bending in the Z-axis direction. Since the acceleration is calculated by detecting the drive vibration frequency associated with the drive vibration of the second piezoelectric element 8, the detection is also easy.

  In the embodiment of the present invention, in the calculation of the acceleration sensor, the acceleration is calculated by detecting the driving vibration frequency accompanying the driving vibration of the second piezoelectric element 8. The acceleration may be calculated by detecting the capacitance between the drive positive electrode 20 and the drive negative electrode 18.

  That is, since the distance between the drive positive electrode 20 and the drive negative electrode 18 changes with the drive vibration of the second piezoelectric element 8, this is detected and calculated as a change in capacitance.

  Further, the positions of the frame-like fixed base 1 and the central base 3 may be in a form other than that shown in FIG. For example, it is a form shown in FIG. In FIG. 10, two first piezoelectric elements 4 and two weights 6 are arranged symmetrically with respect to the central base 3, and angular velocities around the Z axis, X axis, and acceleration in the Y axis direction are calculated. can do.

  Since the two first piezoelectric elements 4 are arranged symmetrically around the central base 3 and the two second piezoelectric elements 8 and the weight part 6 are arranged symmetrically, vibrations at the time of driving vibration are canceled and absorbed. Can improve accuracy.

  As described above, the composite sensor according to the present invention can be used for various electronic devices such as attitude control and navigation of moving bodies such as aircraft, automobiles, robots, ships, and vehicles.

The perspective view of the compound sensor used as the premise example of this invention Enlarged perspective view of part A in FIG. AA sectional view of FIG. BB sectional view of FIG. AA sectional view of FIG. The perspective view which shows the drive state of the composite sensor The perspective view of the A section of FIG. 6 which shows the operation state of the composite sensor The perspective view of the A section of FIG. 6 which shows the operation state of the composite sensor The perspective view of the B section of Drawing 6 showing the operating state of the compound sensor The top view of the vibrator of the compound sensor in one embodiment of the present invention

DESCRIPTION OF SYMBOLS 1 Frame-shaped fixed base 2 Connection part 3 Center base 4 1st piezoelectric element 6 Weight part 8 2nd piezoelectric element 10 Vibrator 11 Substrate 12 1st arm 14 2nd arm 16 Connection part 18 Driving negative electrode 20 Driving positive electrode 22 Detection Positive electrode 23 Detection negative electrode 26 Silicon plate 28 Lower electrode 30 PZT piezoelectric body 32 Upper electrode

Claims (1)

A rectangular frame-shaped fixed base having four corners;
A central base connected by four connecting portions to four corners of the frame-shaped fixed base;
Two angular velocity sensors symmetrically arranged in a uniaxial direction around the central base;
Two acceleration sensors arranged symmetrically in the direction of the other axis different from the angular velocity sensor around the central base,
In the X axis, the Y axis, and the Z axis that are substantially orthogonal to each other,
Two angular velocity sensors arranged symmetrically in the Y- axis direction around the central base,
Two acceleration sensors arranged symmetrically in the X- axis direction around the central base,
The angular velocity sensor has a T shape in which one end of the first arm arranged in the Y-axis direction is connected to the central base, the other end is connected to the center of the second arm, and the second arm is arranged in the X-axis direction. And arranging a first detection positive electrode and a first detection negative electrode on the first arm,
A first piezoelectric element in which a first drive positive electrode and a first drive negative electrode are arranged on the second arm;
In the acceleration sensor, the weight portion and the central base portion are connected by a second piezoelectric element including a second drive positive electrode, a second drive negative electrode, a second detection positive electrode, and a second detection negative electrode. With configuration ,
In the angular velocity sensor, the second arm vibrates in the Y-axis direction,
In the acceleration sensor, the second piezoelectric element is driven and vibrated in the Z-axis direction .

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