JP2007198777A - Inertia force sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inertia force sensor capable of detecting a plurality of inertia forces different from one another such as angular velocity and acceleration, detecting an inertia force on a plurality of detection axes, and achieving compactness of various types of electronic apparatuses. <P>SOLUTION: The inertia force sensor is provided with a detection element 1 for detecting inertia forces. The detection element 1 comprises a fixing arm 2 of which both end parts are fixed; two first arms 4 and a second arm 6 connected to the fixing arm 2 in approximately orthogonal directions. The second arm 6 is connected between the two first arms 4. The first arms 4 and the second arm 6 are especially extended in opposite directions with respect to the fixing arm 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inertial force sensor that detects an inertial force 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 inertial force sensor will be described.

  Conventionally, when an inertial force sensor that detects an inertial force such as an angular velocity or acceleration is used, a dedicated angular velocity sensor is used to detect the angular velocity, and a dedicated acceleration sensor is used to detect the acceleration. In addition, when detecting angular velocities and accelerations of a plurality of detection axes with respect to the X axis, Y axis, and Z axis orthogonal to each other, a plurality of angular velocity sensors and acceleration sensors are used so as to correspond to the number of detection axes. It was.

  Therefore, when various angular velocity and acceleration are detected in combination with various electronic devices, or when angular velocity and acceleration are detected for multiple detection axes, multiple angular velocity sensors and acceleration sensors are mounted on various electronic devices. Each was mounted on a board.

  In general, an angular velocity sensor detects an angular velocity by electrically detecting a distortion of a detection element caused by the generation of Coriolis force by vibrating a detection element having various shapes such as a sound shape, an H shape, and a T shape. The 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.

  A plurality of inertial force sensors such as an angular velocity sensor and an acceleration sensor are used in an attitude control device, a navigation device, and the like of a moving body such as a vehicle, corresponding to the inertial force and 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, when detecting the inertial force of various electronic devices, a plurality of inertial force sensors such as an angular velocity sensor and an acceleration sensor are mounted on the mounting board of the various electronic devices corresponding to the inertial force and detection axis to be detected. Therefore, it is necessary to secure a mounting area for mounting a plurality of inertial force sensors, and there is a problem that various electronic devices cannot be reduced in size.

  The present invention solves the above problems and does not require a mounting area for mounting a plurality of inertial force sensors, detects a plurality of different inertial forces such as angular velocity and acceleration, or detects a plurality of detection axes. An object of the present invention is to provide an inertial force sensor that can detect inertial force and can reduce the size of various electronic devices.

  In order to achieve the above object, the present invention particularly provides a detection element having a fixing arm having both ends fixed to a mounting substrate, and two first and second arms connected to the fixing arm in a substantially orthogonal direction. And the second arm is connected between the two first arms.

  With the above configuration, when the fixing arm is arranged in the X-axis direction and the first and second arms are arranged in the Y-axis direction with respect to the X-axis, Y-axis, and Z-axis orthogonal to each other, If both ends of the first arm are driven and oscillated in the X-axis direction, distortion caused by the angular velocity around the Z-axis can be generated in the Y-axis direction of the fixing arm or the X-axis direction of the second arm, Strain caused by the angular velocity around the Y axis can be generated in the Z-axis direction of the first arm, and can be detected by detecting this strain.

  As for acceleration, for example, distortion caused by acceleration in the Y-axis direction can be generated in the fixing arm, and distortion caused by acceleration in the X-axis direction can be generated in the third arm. It can be detected if it is detected.

  Therefore, a plurality of different inertia forces can be detected, or the inertia forces of a plurality of detection shafts can be detected, so that the mounting area can be reduced and the size can be reduced.

  FIG. 1 is a perspective view of a detection element of an inertial force sensor according to an embodiment of the present invention, and FIG. 2 is an operation state diagram of the detection element.

  In FIG. 1, an inertial force sensor according to an embodiment of the present invention includes a detection element 1 for detecting inertial force and a processing circuit (not shown). The detection element 1 has a fixing arm 2 having both ends fixed, and two first arms 4 and second arms 6 connected to the fixing arm 2 in a substantially orthogonal direction. In this configuration, the first arms 4 are connected. In particular, the first arm 4 and the second arm 6 extend in directions opposite to each other with respect to the fixing arm 2.

  In addition, the detection element 1 has a fixing arm 2 arranged in the X-axis direction and a first arm 4 and a second arm 6 arranged in the Y-axis direction on the X, Y, and Z axes orthogonal to each other. Yes.

  Further, the detection element 1 is integrally formed from a silicon substrate. On this silicon substrate, a drive electrode is disposed on an arm for driving vibration, and a detection electrode is disposed on an arm for detecting strain. In this detection element 1, the arms for driving vibration are the both ends of the first arm 4, and the arms for detecting distortion are the fixing arm 2, the first arm 4, and the second arm 6.

  For the drive electrode and the detection electrode, for example, a lower electrode of Pt is formed on a silicon substrate by high frequency sputtering, a PZT piezoelectric body is formed on the upper portion of this lower electrode by high frequency sputtering, and an upper portion is formed by Au evaporation on the upper portion. What is necessary is just to form by forming an electrode.

  When an alternating voltage with a resonance frequency at which silicon resonates is applied to the lower electrode and the upper electrode, the arm on which the drive electrode is arranged vibrates and if the arm is distorted due to angular velocity or acceleration, it is placed on the distorted arm. A voltage corresponding to the strain is output from the detected electrode. Based on this output voltage, the processing circuit can detect the angular velocity and acceleration.

  With the above configuration, for example, as shown in FIG. 2, if the angular velocity is driven and vibrated in the X axis direction at both ends of the first arm 4 (solid arrows and dotted arrows are alternately repeated), the Z axis Distortion caused by the rotational angular velocity can be generated in the Y-axis direction of the fixing arm 2 or in the X-axis direction of the second arm 4 (Coriolis force in the Y-axis direction of the first arm 2 corresponding to the drive vibration). Therefore, distortion caused by the angular velocity around the Y axis can be generated in the Z axis direction of the first arm 4 (Coriolis force is generated in the Z axis direction of the first arm 4 in response to the drive vibration). Therefore, detection is possible by detecting this distortion.

  As for acceleration, for example, distortion caused by acceleration in the Y-axis direction can be generated in the fixing arm 2 (because the weights of the first arm 4 and the second arm 6 are applied to the fixing arm 2), and the X-axis Distortion due to direction acceleration can be generated in the first arm 4 or the second arm 6 (because the weights of the first arm 4 and the second arm 6 are applied to the first arm 4 and the second arm 6, respectively). Detection is possible by detecting this distortion.

  Therefore, a plurality of different inertia forces can be detected, or the inertia forces of a plurality of detection shafts can be detected, and the mounting area can be reduced and the size can be reduced.

  In addition, when a weight part is connected to the both ends of the 2nd arm 6, while being able to improve the detection sensitivity of an acceleration, the amplitude in a drive vibration becomes large and the detection sensitivity of an angular velocity can be improved.

  The inertial force sensor according to the present invention can detect a plurality of inertial forces or detect inertial forces of a plurality of detection shafts, and can be applied to various electronic devices.

The perspective view of the detection element of the inertial force sensor in one embodiment of this invention Operation state diagram of detection element of the same inertial force sensor

Explanation of symbols

2 Fixing arm 4 First arm 6 Second arm

Claims (4)

It has a detection element that detects inertial force,
The detection element includes a fixing arm whose both ends are fixed to a mounting substrate, and two first and second arms connected to the fixing arm in a substantially orthogonal direction, and the second arm includes two An inertial force sensor connected between the first arms. The inertial force sensor according to claim 1, wherein the first arm and the second arm extend in directions opposite to each other with respect to the fixing arm. 2. The inertial force sensor according to claim 1, wherein an end portion of the first arm is driven to vibrate to detect an angular velocity by detecting distortion of the second arm. The inertial force sensor according to claim 1, wherein an acceleration is detected by detecting distortion of the fixing arm.

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