JP2006226802A - Compound sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound sensor for achieving miniaturization of a mounting substrate by compounding an angular speed sensor and an acceleration sensor to reduce a mounting area without needing the mounting area of the angular speed sensor and the mounting area of the acceleration sensor. <P>SOLUTION: The compound sensor having the angular speed sensor and the acceleration sensor is provided with two cone parts 8 connected to a fixing base part 4, a first vibrating element 10 for connecting one end to one cone part 8 and connecting the other end to the other cone part 8, and a second vibrating element 12 for connecting one end to the cone part 8. The first vibrating element 10 and the second vibrating element 12 are driven and vibrated, and drive vibration of the first vibrating element 10 changed by being caused by movement of the cone part 8 is detected to detect an acceleration. Curvature vibration of the second vibrating element 12 changed by being caused by Coriolis force is detected to detect an angular speed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 distortion of the vibrator accompanying the generation of Coriolis force to detect angular velocity To do.

  Moreover, the conventional acceleration sensor has a weight part, and detects acceleration by comparing and detecting the movement of the weight part accompanying the acceleration with that 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.

  The present invention solves the above-described problems, and 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 to provide a combined sensor.

  In order to achieve the above object, the present invention particularly relates to two weight parts connected to a fixed base, and a first vibration element having one end connected to one of the weight parts and the other end connected to the other weight part. And a second vibration element having one end connected to the weight portion, wherein the first vibration element and the second vibration element are driven to vibrate with each other, and the first vibration changes due to the movement of the weight portion. The driving vibration of the element is detected to detect acceleration, and the angular vibration is detected by detecting the bending vibration of the second vibrating element that changes due to the Coriolis force.

  With the above configuration, the first and second weight parts connected to the fixed base, the first vibration element having one end connected to one weight part and the other end connected to the other weight part, and the first connected to the weight part. Since the first vibration element and the second vibration element are driven to vibrate with each other, the acceleration sensor detects the drive vibration of the first vibration element that changes due to the movement of the weight portion. The acceleration can be detected, and the angular velocity sensor can detect the angular velocity by detecting the bending vibration of the second vibration element.

  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, the invention described in all claims of the present invention will be described using embodiments with reference to the drawings.

  1 is a perspective view of a composite sensor without a case according to an embodiment of the present invention, FIG. 2 is a perspective view of a portion A in FIG. 1, FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4, FIG. 6 is a cross-sectional view taken along the line BB in FIG. 4, and FIG. 7 is a perspective view showing a driving state and an operating state of the part A in FIG. FIG. 8 is an acceleration detection circuit diagram, FIG. 9 is a waveform diagram of a drive signal when driving the first vibration element, FIG. 10 is a perspective view showing a drive state of the B part of FIG. 1, and FIG. FIG. 12 is a perspective view showing an operating state, FIG. 12 is a perspective view showing a driving state of a portion B in FIG. 1, and FIG. 13 is an angular velocity detection circuit diagram.

  1 to 3, the composite sensor without a case in one embodiment of the present invention is a composite sensor having an angular velocity sensor and an acceleration sensor, and a fixed base having two support shaft portions 2 for mounting on a substrate. 4 and two spindle parts 2 connected between the two spindle parts 2 and provided with a groove 6 between the two peripheral spindle parts 2 from the outer peripheral edge, and one spindle part 8 with one end , Two first vibration elements 10 having the other end connected to the other weight 8, two second vibration elements 12 having one end connected to the bottom of the groove 6 provided in the weight 8, and a signal And a substrate 14 on which a processing circuit is mounted and on which two support shafts 2 of the fixed base 4 are attached and supported. Then, the first vibration element 10 and the second vibration element 12 are driven to vibrate with each other, the driving vibration of the first vibration element 10 that changes due to the movement of the weight portion 8 is detected to detect acceleration, and Coriolis is detected. The angular velocity is detected by detecting the bending vibration of the second vibrating element 12 that changes due to the force.

  The first vibration element 10 has a slit shape in which three filaments 16 are provided side by side, and the second vibration element 12 has a T shape having a first arm 18 and a second arm 20 that are connected substantially orthogonal to each other. The two weight portions 8, the two first vibration elements 10, and the two second vibration elements 12 are arranged to face each other with respect to the fixed base 4, and the two first vibration elements 10 and the two second vibration elements 12 are The straight line connecting the two first vibration elements 10 and the fixed base 4 and the straight line connecting the two second vibration elements 12 and the fixed base 4 are arranged so as to be substantially orthogonal. With such an arrangement, when the two first vibrating elements 10 are arranged on the X axis and the two second vibrating elements 12 are arranged on the Y axis in the X axis, the Y axis, and the Z axis substantially orthogonal to each other, The two weight portions 8 are arranged symmetrically with respect to the X axis.

  In the first vibrating element 10, two of the three filaments 16 are provided with drive electrodes for applying drive vibration, and the remaining one is provided with a detection electrode for detecting drive vibration. A Pt lower electrode 24 is formed on the silicon plate 22 by high frequency sputtering, a PZT piezoelectric body 26 is formed on the lower electrode 24 by high frequency sputtering, and an upper electrode 28 is formed on the upper portion by Au evaporation. is doing. When an AC voltage having a resonance frequency at which silicon resonates is applied to the lower electrode 24 and the upper electrode 28, the PZT piezoelectric body 26 expands and contracts, and the two filaments 16 drive and vibrate. When the linear member 16 vibrates, the three linear members 16 influence each other, so that the driving vibration is detected from the linear member 16 on which the detection electrodes are arranged.

  4 to 6, similarly to the first vibration element 10, the second vibration element 12 is provided with a drive electrode for applying drive vibration, and further detects bending vibration caused by angular velocity. The detection electrodes are arranged. The first arm 18 is provided with the drive positive electrode 32 and the drive negative electrode 30 so that the drive negative electrode 30 is sandwiched between the two drive positive electrodes 32, and the drive positive electrode 32 and the drive negative electrode 30 are sandwiched therebetween. Thus, the detection positive electrode 34 and the detection negative electrode 36 are arranged. On the second arm 20, the driving negative electrode 30 arranged on the first arm 18 is arranged in a T shape, and the driving positive electrode 32 is arranged in an L shape. Of the two drive positive electrodes 32, one drive positive electrode 32 may be used as a monitor positive electrode for monitoring drive vibration, and the drive negative electrode 30 may be shared as a monitor negative electrode.

  In the second vibrating element 12, a Pt lower electrode 24 is formed on a silicon plate 22 by high frequency sputtering, a PZT piezoelectric body 26 is formed on the lower electrode 24 by high frequency sputtering, and further on the upper portion. The upper electrode 28 is formed by Au deposition. The upper electrode 28 is composed of a drive positive electrode 32 and a drive negative electrode 30, and when an AC voltage having a resonance frequency at which silicon resonates is applied, the PZT piezoelectric body 26 expands and contracts on each of the drive positive electrode 32 side and the drive negative electrode 30 side. Occurs, and the second arm 20 vibrates.

  Next, an operation when drive vibration and acceleration of the first vibration element 10 occur will be described.

  As shown in FIG. 7, the first vibrating elements 10 are driven to vibrate in the direction of the arrows. In the first vibrating element 10, among the three linear bodies 16, the driving directions of the adjacent linear bodies 16 are opposite to each other, and the linear bodies 16 are moved in the Z axis (+ Z) direction and (−Z). Drive and vibrate to alternate with direction. In the state where this drive vibration is applied, the drive vibration of the first vibration element 10 that changes due to the movement of the weight portion 8 is detected to detect the acceleration.

  For example, as shown in FIGS. 1 and 7, when acceleration occurs in the (−X) direction side of the X axis (the two weight portions 8 try to move in the (+ X) direction of the X axis), (+ X) A compressive stress is generated in the direction of the first vibration element 10 on the direction side in the arrow direction (A). At this time, a tensile stress is generated in the first vibration element 10 on the (−X) direction side.

  Further, when acceleration occurs in the (+ X) direction side of the X axis (the two weight portions 8 try to move in the (−X) direction of the X axis), the first vibration element 10 on the (+ X) direction side has A tensile stress is generated in the arrow direction (B). At this time, a compressive stress is generated in the first vibration element 10 on the (−X) direction side.

  Different tensions are applied to the two first vibration elements 10 according to the movement of the weight 8, and the natural resonance frequencies of the two first vibration elements 10 change as compared with the state before the movement of the weight 8. (The frequency of the drive vibration wave of one first vibration element 10 is increased, and the frequency of the drive vibration wave of the other first vibration element 10 is decreased), so that the acceleration can be detected by detecting the difference between the natural resonance frequencies. can do.

  In addition, the phase of the drive vibration wave of the two first vibration elements 10 changes as compared with the state before the weight 8 is movable (the phase of the drive vibration wave of the negative first vibration element 10 advances, the other Since the phase of the driving vibration wave of the first vibration element 10 is delayed), the acceleration can be detected even if the difference between the driving vibration waves is detected.

  When detecting the acceleration, for example, an acceleration detection circuit as shown in FIG. 8 is used to detect and detect the respective drive signals based on the drive vibration waves of the two first vibration elements 10 by synchronous detection. A resistor 38, an amplifier 40, a band pass filter 42, an AGC circuit 44, a synchronous detection circuit 46, and a low pass filter 48 are connected to the first vibration element 10 of the acceleration detection circuit. An acceleration is detected by detecting a phase difference caused by a change in frequency. At this time, as shown in FIG. 9, if the drive signal wave of the drive signal before the weight portion 8 is moved is the drive signal wave A, the drive signal wave of the drive signal after the weight portion 8 is moved is one of the first signal waves. The phase corresponding to the vibration element 10 becomes the drive signal wave B with a phase delay, and the phase corresponding to the other first vibration element 10 becomes the drive signal wave C with the phase advanced.

  Next, the operation when the drive vibration and the angular velocity of the second vibration element 12 occur will be described.

  As shown in FIG. 10, the second vibrating element 12 vibrates and drives the both ends of the second arm 20 to alternately repeat in the (+ Y) direction and the (−Y) direction of the Y axis. In the state where this driving vibration is applied, the angular vibration is detected by detecting the bending vibration of the second vibration element 12 that changes due to the Coriolis force. When bending vibration is generated in the second vibration element 12, the PZT piezoelectric body 26 formed on the silicon plate 22 is distorted, and charges are generated in the detection positive electrode 34 and the detection negative electrode 36, which are detected.

  For example, as shown in FIG. 11, when an angular velocity is generated around the X axis, the angular velocity is detected by detecting the bending vibration of the first arm 18 in the Z axis direction. Since the second arm 20 bends and vibrates so that the entirety repeats alternately in the (+ Z) direction and the (−Z) direction of the Z axis, the first arm 18 also follows the (+ Z) direction of the Z axis (−Z). ) Bend and vibrate to repeat alternately in the direction.

  For example, as shown in FIG. 12, when an angular velocity occurs around the Z-axis, the angular velocity is detected by detecting the bending vibration of the first arm 18 in the X-axis direction. Since the second arm 20 bends and vibrates so that the entirety repeats alternately in the (+ X) direction and the (−X) direction of the X axis, the first arm 18 also follows the (+ X) direction and the (−X) direction of the X axis. ) Bend and vibrate to repeat alternately in the direction.

  When the angular velocity is detected, for example, an angular velocity detection circuit as shown in FIG. 13 is used to detect and detect the respective bending signals based on the bending vibration waves of the two second vibrating elements 12. A resistor 38, an amplifier 40, a band pass filter 42, an AGC circuit 44, a synchronous detection circuit 46, and a low pass filter 48 are connected to the second vibration element 12 of this angular velocity detection circuit. The angular velocity is detected by detecting the difference in resonance frequency or the phase difference of the driving vibration wave.

  With the above configuration, the two weight portions 8 connected to the fixed base portion 4, the first vibration element 10 having one end connected to one weight portion 8 and the other end connected to the other weight portion 8, and the weight portion 8. The first vibration element 10 and the second vibration element 12 are driven and vibrated with each other, so that the acceleration sensor is a first variable that changes due to the movement of the weight portion 8. The acceleration can be detected by detecting the driving vibration of the first vibration element 10, and the angular velocity can be detected by detecting the bending vibration of the second vibration element 12 as the angular velocity sensor. That is, the angular velocity sensor and the acceleration sensor can be combined, and the mounting area can be reduced and the mounting substrate 14 can be downsized.

In detecting the acceleration, the difference in natural resonance frequency in the drive vibration of the first vibration element 10,
Or if the phase difference of the drive vibration wave in the drive vibration of the two 1st vibration elements 10 is detected, it can detect easily and accurately. At this time, if the first vibrator has a slit shape in which a plurality of linear bodies 16 are provided side by side, and the adjacent linear bodies 16 are driven to vibrate in opposite directions, sensitivity is amplified and detection can be performed with very high accuracy. In particular, if the groove 6 is provided from the outer peripheral edge toward the fixed base 4 and the second vibration element 12 is connected to the bottom of the groove 6, the driving vibration and bending vibration of the second vibration element 12 are not affected. The sensitivity of the first vibration element 10 can be further amplified.

  In detecting the angular velocity, the second vibrator has a T shape having a first arm 18 and a second arm 20 which are connected substantially orthogonally to each other, the first arm 18 is connected to the weight portion 8, and the second arm is connected. By driving and vibrating 20, the angular velocity in the biaxial direction can be detected and the height can be reduced.

  Further, since the two first vibration elements 10 are arranged opposite to the fixed base 4 and the two first vibration elements 10 and the fixed base 4 are arranged on a straight line, the first vibration element 10 is driven. In addition to suppressing the noise caused, the two second vibration elements 12 are arranged opposite to the fixed base 4 and the two second vibration elements 12 and the fixed base 4 are arranged in a straight line. Noise caused by driving the vibration element 12 can be suppressed, and acceleration and angular velocity can be detected with higher accuracy. In particular, since the straight line connecting the two first vibration elements 10 and the fixed base 4 and the straight line connecting the two second vibration elements 12 and the fixed base 4 are substantially orthogonal to each other, the shape becomes symmetrical and the first vibration Noise due to driving of the element 10 and the second vibration element 12 can be further suppressed.

  Further, the fixed base 4 has two support shaft portions 2 for mounting the substrate 14, and if the weight portion 8 is connected between the support shaft portions 2, the fixed base 4 can be accurately mounted on the substrate 14. The noise resulting from the movement of the weight 8 can be suppressed.

  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.

1 is a perspective view of a composite sensor without a case in one embodiment of the present invention. Enlarged perspective view of part A in FIG. AA sectional view of FIG. Enlarged perspective view of part B in FIG. AA sectional view of FIG. BB sectional view of FIG. The perspective view which shows the drive state and operation | movement state of the A section of FIG. Acceleration detection circuit diagram Drive signal waveform diagram The perspective view which shows the drive state of the B section of FIG. The perspective view which shows the operation state of the B section of FIG. The perspective view which shows the drive state of the B section of FIG. Angular velocity detection circuit diagram

Explanation of symbols

2 Supporting shaft portion 4 Fixed base portion 6 Groove 8 Weight portion 10 First vibration element 12 Second vibration element 14 Substrate 16 Linear body 18 First arm 20 Second arm 22 Silicon plate 24 Lower electrode 26 PZT piezoelectric body 28 Upper electrode 30 Drive negative electrode 32 Drive positive electrode 34 Detection positive electrode 36 Detection negative electrode 38 Resistance 40 Amplifier 42 Band pass filter 44 AGC circuit 46 Synchronous detection circuit 48 Low pass filter

Claims (10)

A combined sensor having an angular velocity sensor and an acceleration sensor, the first vibration having two weight parts connected to a fixed base and one end connected to one of the weight parts and the other end connected to the other weight part. An element and a second vibration element having one end connected to the weight portion are provided, the first vibration element and the second vibration element are driven to vibrate with each other, and the first change is caused by the movement of the weight portion. A composite sensor that detects an acceleration by detecting a driving vibration of a vibration element and detects an angular velocity by detecting a bending vibration of the second vibration element that changes due to a Coriolis force. 2. The composite sensor according to claim 1, wherein the two first vibration elements are arranged opposite to the fixed base, and the two first vibration elements and the fixed base are arranged on a straight line. The composite sensor according to claim 2, wherein acceleration is detected by detecting a difference between natural resonance frequencies in driving vibration of the two first vibration elements. The composite sensor according to claim 2, wherein an acceleration is detected by detecting a phase difference between driving vibration waves in driving vibration of the two first vibration elements. 2. The composite sensor according to claim 1, wherein the two second vibration elements are disposed to face the fixed base, and the two second vibration elements and the fixed base are disposed on a straight line. The two first vibration elements are disposed opposite to the fixed base, the two second vibration elements are disposed opposite to the fixed base, and the two first vibration elements and the fixed base are disposed. The composite sensor according to claim 1, wherein a straight line connecting and a straight line connecting two second vibration elements and the fixed base are substantially orthogonal. The composite sensor according to claim 1, wherein the weight portion has a groove from an outer peripheral edge toward the fixed base, and the second vibration element is connected to a bottom portion of the groove. 2. The composite sensor according to claim 1, wherein the first vibrating element has a slit shape in which a plurality of linear bodies are provided side by side, and the adjacent linear bodies are driven and vibrated in directions opposite to each other. The second vibration element has a T shape having a first arm and a second arm that are connected substantially orthogonally to each other, wherein the first arm is connected to the weight portion, and the second arm is driven to vibrate. The composite sensor according to 1. The composite sensor according to claim 1, wherein the fixed base portion has two support shaft portions for board mounting, and the weight portion is connected between the support shaft portions.

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