JP2004150996A - Electrode structure of angular velocity detecting sensor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angular velocity detecting sensor element removing electrostatic leak (crosstalk) when adjusting a tuning fork type gyroscope. <P>SOLUTION: This electrode structure of an angular velocity detecting sensor element is characterized in that a signal pad for connecting to an excitation electrode on a sensor element surface and a signal pad for connecting to an angular velocity detecting electrode are disposed on different surfaces of on the sensor element surface. The signal pad parts of the excitation electrode and the angular velocity detecting electrode are disposed on the different surfaces respectively so as to reduce capacitive coupling between signal pad parts of the electrodes and reduce electrostatic leak. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, when the vibrator is excited in the X-axis direction by applying an AC voltage (excitation vibration signal) to the excitation electrode, the rotational angular velocity of the vibrator acting around the Y-axis direction is determined by the Coriolis force. The present invention relates to a piezoelectric vibration type angular velocity sensor element for detecting the magnitude of angular velocity based on the amount of electric charge generated in an angular velocity detecting electrode.
[0002]
[Prior art]
Conventionally, various gyroscopes (hereinafter, referred to as gyroscopes) have been developed as sensors for detecting angular velocity. The types are roughly classified into mechanical gyroscopes, mechanical gas gyroscopes, vibrating gyroscopes using vibrating vibrating reeds and tuning forks, optical fiber gyroscopes, and ring laser gyroscopes. The optical gyro uses the Sagnac effect, and the others use the Coriolis force, which is one of the inertial forces (apparent force) when rotating, to detect angular velocity. Depending on the intended use, accuracy, price and dimensions The sensor to be used is selected in consideration of the above.
[0003]
A piezoelectric vibration type angular velocity sensor is mounted on a vehicle or aircraft to record its running or flight trajectory, and to detect the angular velocity (angular velocity of rotation in a plane horizontal to the earth centered on the vertical line) generated when turning. That is being done. In automotive applications, it is used for control of chassis systems and calculation of direction of navigation systems. For example, in the case of vehicle attitude control during a sharp turn, in order to improve the attitude control performance, the angular velocity and roll rate (the angular velocity of rotation about the vehicle traveling direction as an axis) are fed back to the control system as the attitude information of the vehicle. Used. In the case of a navigation system, it is used to calculate the turning angle of the vehicle by integrating the angular velocity with time. Further, the angular velocity sensor is mounted on a robot, and is applied to attitude control thereof. In addition, they are also used in camera shake correction systems for video cameras and still cameras.
[0004]
FIG. 1 is a perspective view of an example showing a main part of a tuning fork type angular velocity sensor element 1 using quartz. In the figure, 1 is a sensor element (quartz plate), 3-1 and 3-2 are excitation electrodes, 4-1 and 4-2 are angular velocity detection electrodes, and excitation electrodes 4-1 and 4-2 are sensor elements 1 The electrodes 4-1 and 4-2 for angular velocity detection are provided on the left and right surfaces of one of the two legs 2-1 and 2-2 facing each other. Have been. In FIG. 1, the excitation electrode is disposed on the leg 2-2, and the detection electrode is disposed on the leg 2-1.
[0005]
In this angular velocity sensor element, as shown in FIG. 2, the excitation electrode 3-1 is connected to the terminal P1, and the excitation electrode 3-2 is connected to the terminal P2. The detection electrode 4-1 is connected to the terminal P3, and the detection electrode 4-2 is connected to P4.
[0006]
Here, the direction parallel to the short side of the sensor element 1, the direction of the electric axis of the quartz crystal is the X-axis direction, the direction of the long side is the Y-axis direction, and the direction orthogonal to the XY plane (the direction perpendicular to the plate surface of the sensor element). ) Is the Z-axis direction. Here, when an AC voltage (excitation vibration signal) e1 is applied between the terminals P1 and P2, an electric field is generated in the crystal as shown in the leg 2-2 in FIG. At this time, a distortion proportional to the magnitude of the X-axis component of the electric field occurs in the Y-axis direction in the excitation leg. Next, when an electric field is generated in the opposite direction, the two legs 2-1 and 2-2 of the sensor element 1 vibrate in the X-axis direction in opposite phases.
[0007]
At this time, when a rotational angular velocity acts around the Y axis, that is, when the sensor element 1 rotates about the Y axis, a Z-axis vibration component is generated by Coriolis force. Since the magnitude of the amplitude of this vibration component is proportional to the Coriolis force, two legs 2-1 and 2-2 of the sensor element 1 are charged with an amount of electric charge proportional to the rotational angular velocity by the piezoelectric effect. appear.
[0008]
As a result, electric charges are generated between the terminals P3 and P4 in the direction indicated by the arrow and then in the opposite direction between the terminals P3 and P4 as shown in the middle leg portion 2-1 in FIG. 2, and an electric signal corresponding to the Coriolis force is generated. es1 is obtained. The magnitude of the rotational angular velocity acting around the Y-axis direction can be known from the magnitude of the electric signal es1. The electric signal es1 is basically obtained as a sine curve. By comparing the phase of the waveform of the electric signal es1 with the waveform of the AC voltage e1 (excitation waveform), the direction of the rotational angular velocity is determined by the phase lead / lag. You can also know.
[0009]
Also, the electric signal es1 obtained between the terminals P3 and P4 is orders of magnitude smaller than the AC voltage e1 applied between the terminals P1 and P2.
[0010]
The terminals P1, P2, P3, and P4 are respectively connected to the outside by wire bonding.
[0011]
[Patent Document 1]
JP 2002-039760 A
[Problems to be solved by the invention]
When the distance between the electrodes becomes narrower with the downsizing of the angular velocity detection sensor element, the signal potential between the electrodes in the angular velocity detection sensor element differs, so that signal transmission due to capacitive coupling occurs, which is an unnecessary signal in the detection signal. Is detected. This is called electrical crosstalk. An angular velocity detection sensor element having a structure for reducing the influence of the electric crosstalk is provided.
[0013]
[Means for Solving the Problems]
In order to solve the problem, the present invention provides an angular velocity detection sensor element using a tuning fork type vibrator having at least two legs protruding from a base parallel to the Y axis.
A signal pad for connecting to the excitation electrode on the sensor element surface and a signal pad for connecting to the angular velocity detection electrode on different surfaces of the sensor element surface, respectively. Electrode structure.
[0014]
The electrode structure of the angular velocity detection sensor element is also characterized in that one of the signal pad portions is formed by a bump and is used for connection for conduction with the outside.
[0015]
In short, in an angular velocity detecting sensor element using a tuning fork type vibrator having at least two legs protruding from the base parallel to the Y axis, the excitation electrode and the angular velocity detecting electrode arranged on the legs are connected to the signal pad of the base. Although connected, the signal pad portion of the excitation electrode and the signal pad portion of the angular velocity detection electrode arranged on this base are respectively arranged on the back surface, so that the capacitance generated in the signal pad portion of the excitation electrode and the angular velocity detection electrode By reducing the coupling and arranging the signal pads on different surfaces, the distance between the excitation electrode and the angular velocity detection electrode can be increased, so that the capacitive coupling between the electrodes can be reduced.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same reference numeral indicates the same object.
[0017]
FIG. 5 is a perspective view showing an example of an angular velocity detecting sensor element shown in the sensor element 5 of FIGS. 3 and 4. Here, FIG. 4 is a perspective view showing the sensor element 5 of FIG. 3 inverted by 180 degrees around the Y axis. FIG. 5 is an arrangement view of the electrodes when the sensor element 5 of FIG. 3 is viewed from above in a direction perpendicular to the Y axis.
[0018]
The electrodes 6-1 and 6-2 arranged on the leg 2-4 shown in FIGS. 3, 4 and 5 are excitation electrodes, and the electrodes 7-1 and 7-2 arranged on the leg 2-3 are Angular velocity detection electrode. The excitation electrode 6-1 is connected to the terminal P5 as shown in FIG. 5, and the excitation electrode 6-2 is connected to the terminal P6. The angular velocity detecting electrode 7-1 is connected to the terminal P8, and the angular velocity detecting electrode 7-2 is connected to the terminal P7.
[0019]
The terminals P5 and P6 and the terminals P7 and P8 are arranged on the surfaces opposite to each other as shown in FIGS. Therefore, when the sensor element 5 of the present invention is mounted and supported on the support 8, the surface on which the signal pad 10 of the detection electrode, which is the surface in FIG. The signal pad 10 is connected to an external terminal for bonding, and the surface of the excitation electrode, which is the surface of FIG. 3 where the signal pad 10 is located, is connected to the external terminal by wire bonding. FIG. 6 is a perspective view showing a supporting structure of such an angular velocity detecting sensor element 5.
[0020]
FIG. 6 shows an example of mounting and supporting the sensor element 5 of the present invention (detailed electrode structure is not shown). A bump 9 is formed on a signal pad of the sensor element 5, and a connection terminal of the support 8 is provided. An electrical connection is made with the unit 11. Therefore, the surface of the sensor element 5 in contact with the support base 8 is connected by the bump 9, and the surface seen as the surface of the sensor element 5 is electrically connected, for example, by wire connection. The method for detecting the angular velocity of the sensor element 5 according to the present invention is the same as that of the conventional type shown in FIGS.
[0021]
Although the angular velocity detecting sensor element shown in the present embodiment has been described by taking a tuning fork type shape as an example, the shape of the sensor element 5 is not limited to the tuning fork type shape, and an H-shaped leg having legs extending in both directions. It goes without saying that the same effect can be obtained even if it has a structure or a shape having a plurality of legs in the same direction.
[0022]
【The invention's effect】
According to the present invention, by arranging the signal pads of the excitation electrode and the angular velocity detection electrode on different surfaces, the capacitive coupling of the electrodes (signal pads) can be reduced, and the signal pads can be arranged on different surfaces. Since the distance between the excitation electrode and the detection electrode can be increased, the capacitive coupling between the electrodes can be reduced, and the electric crosstalk can be reduced. Therefore, an unnecessary signal in the detection signal can be reduced. Thereby, a higher sensitivity and higher accuracy angular velocity sensor element can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a conventional angular velocity detection sensor element.
FIG. 2 is an electrode arrangement view of the angular velocity detection sensor element of FIG. 1 viewed from above and perpendicular to the Y axis.
FIG. 3 is a perspective view of the angular velocity detecting sensor element of the present invention as viewed from an excitation electrode side.
FIG. 4 is a perspective view in which the angular velocity detection sensor element of FIG. 3 is rotated by 180 degrees around a Y axis. (Back side of FIG. 3)
FIG. 5 is an electrode arrangement view of the angular velocity detection sensor element of FIGS. 3 and 4 viewed from above and perpendicular to the Y axis.
FIG. 6 is a perspective view showing an example of a supporting form of the angular velocity sensor element of the present invention.
[Explanation of symbols]
1 angular velocity detecting sensor elements 2-1, 2-2, 2-3, 2-4 legs 3-1 and 3-2 excitation electrodes 4-1, 4-2 angular velocity detecting electrodes 5 angular velocity detecting sensor elements 6-1, 6-2 Excitation electrodes 7-1, 7-2 Angular velocity detection electrode 8 Supports P1, P2, P3, P4 Terminals P5, P6, P7, P8 Terminal 9 Bump 10 Signal pad

Claims (2)

In an electrode structure of an angular velocity detection sensor element using a tuning fork type vibrator having at least two legs protruding from a base parallel to the Y axis,
A signal pad for connecting to the excitation electrode and a signal pad for connecting to the angular velocity detection electrode on the sensor element surface, each being arranged on a different surface of the sensor element surface. Electrode structure. 2. An electrode structure for an angular velocity detection sensor element according to claim 1, wherein one of said signal pad portions is formed by a bump and is used for connection for conduction with the outside.

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