JP3136955B2 - Angular velocity detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detector for detecting the angular velocity of a moving object (vehicle) mounted on a car navigation system.

[0002]

2. Description of the Related Art Conventionally, a vibration type angular velocity detecting device is a tuning fork or a complicated structure, and a high-precision one is used.

FIG. 3 is a perspective view showing the structure of such a conventional angular velocity detecting device. In FIG. 3, this example is:
The pedestal 100 is fixed by a support bar 102. The tuning fork vibrator 104 includes two driving vibrators 104a and 104a.
4b with the base block 103 interposed therebetween.
The detecting oscillators 106a and 106b are connected to the driving oscillator 104.
a, 104b and are shifted by 90 degrees. Driving piezoelectric elements 105a and 105b are attached to the driving vibrators 104a and 104b. Further, the detecting piezoelectric elements 10a are attached to the detecting vibrators 106a and 106b.
7a and 107b are attached. Driving piezoelectric elements 105a, 105b and detecting piezoelectric elements 107a, 107
7b are terminals 101a, 101b, 101, respectively.
c, 101d, 101e, and 101f are connected by connection lines (not shown). Terminals 101a to 101f are pedestals 10
0 and is connected to an external circuit board (not shown). Drive signals supplied to two of the terminals 101a to 101f are used to drive the piezoelectric elements 105a and 105b.
Are excited, and the driving vibrators 104a and 104b vibrate.

[0004] The operation of the angular velocity detecting device configured as described above will be described below.

FIG. 4 is a perspective view showing the operating state of the driving vibrators 104a and 104b. In FIG. 4, the driving vibrators 104a and 104b vibrate toward and away from the central axis P. Accordingly, the detection vibrators 106a and 106b also vibrate toward and away from the central axis P. If the apparatus rotates at an angular velocity ω during this vibration, the Coriolis force is generated in the direction perpendicular to the member plane of the detecting vibrators 106a and 106b as shown by the following equation (1).

F = 2mvω (1) The detecting vibrators 106a and 106 are generated by the Coriolis force.
b will bend in a direction perpendicular to this member plane. Due to this deflection, the detecting vibrators 106a, 106
Electric charges are generated in the detecting piezoelectric elements 107a and 107b on the line b. Signal processing is performed on the output of the electric charges.

FIG. 5 is a block diagram showing a signal processing circuit for performing such signal processing. In FIG. 5, charges of the detection piezoelectric elements 107a and 107b are
The signal is amplified by 0, converted into a voltage change, and output from the synchronous detection circuit 151.
To remove the excitation signal component, furthermore, an offset adjustment circuit 152, a level adjustment circuit 153, and a low-pass filter (L
PF) 154 to remove unnecessary signal components, and
By adjusting the output sensitivity to a specified value, the angular velocity ω can be obtained. Also, the charge amplifier 155 for detecting the excitation vibration
As a result, the vibration of the driven tuning fork is detected from one of the driving piezoelectric elements 105a and 105b, and an AGC (automatic gain adjustment circuit) 156 generates a driving signal of a constant level.
Through the drive circuit 157, the driving piezoelectric element 105
a and 105b. That is, the vibration is kept constant by the feedback control.

[0008]

However, in the conventional angular velocity detecting device, the driving vibrators 104a, 104
Unless b and the detecting transducers 106a and 106b are arranged at accurate vertical positions, a correct detection value cannot be obtained, so that high-precision arrangement (assembly) is required. In the case of the tuning fork type, since the driving frequency is determined by the mechanical resonance frequency, it is necessary to perform trimming to set the frequency after assembly. That is, the conventional angular velocity detecting device has a drawback that it is difficult to obtain a high-accuracy detected value, and that assembly is troublesome and costly.

The present invention has been made to solve such a conventional problem, and a highly accurate detection value can be obtained with certainty.
It is an object of the present invention to provide an excellent angular velocity detecting device in which an assembling operation is facilitated and the cost can be reduced.

[0010]

According to a first aspect of the present invention, there is provided an angular velocity detecting apparatus having a thickness-shear vibration mode between a pedestal and a diaphragm, and a driving signal for detecting a vibration of the pedestal side. The surface and the surface on the diaphragm side are in the X-axis direction and 18
Driving elements that vibrate in directions different by 0 degrees are joined and arranged, and at least one set of angular velocity detecting elements are joined and arranged on a vibrating arm provided symmetrically with the center of the diaphragm, In addition, the drive signal supplied to the pedestal and the diaphragm causes the angular velocity detecting element to rotate repeatedly around the center of gravity of the diaphragm at an angle on the XY plane and to vibrate. The vibrating arm is bent by the action of the Coriolis force when an angular velocity is applied, and the angular velocity detecting element outputs a detection signal corresponding to the Coriolis force.

According to a second aspect of the present invention, there is provided an angular velocity detecting device, wherein a piezoelectric element is used as the driving element and the angular velocity detecting element.

[0012]

With such a configuration, in the angular velocity detecting device according to the first and second aspects, the driving element, for example, the driving piezoelectric element vibrates according to the driving signal supplied to the pedestal and the diaphragm. Further, the angular velocity detecting element, for example, the piezoelectric element for angular velocity detection vibrates by repeatedly rotating around the center of gravity of the diaphragm at an angle on the XY plane. The vibrating arm bends due to the action of Coriolis force when angular velocity is applied during this vibration,
The angular velocity detecting element outputs a detection signal corresponding to the Coriolis force. In other words, the vibrating body vibrates in the direction perpendicular to the direction in which the Coriolis force is generated, and the troublesome and high-precision assembly work for accurately arranging the driving vibrator and the detecting vibrator as described above is not required. . In addition, since the frequency of the drive signal depends only on the drive element and is not affected by the mechanical resonance of the diaphragm, the drive frequency is not determined by the mechanical resonance frequency as described above, and the frequency is adjusted. This eliminates the need for trimming. Therefore,
Highly accurate detection values can be reliably obtained, and the assembling work is facilitated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the angular velocity detecting device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view showing the configuration of an embodiment of an angular velocity detecting device according to the present invention. In FIG. 1, in this example, driving piezoelectric elements 202a and 202b having a thickness shear vibration mode are bonded and arranged between a pedestal 200 and a vibration plate 201. A drive signal is supplied from a drive circuit (not shown) between the pedestal 200 and the diaphragm 201, and the input drive signal is applied to each of the driving piezoelectric elements 202a and 202b. Also, the angular velocity detecting piezoelectric elements 203a, 203b, 203c, 203d
Are respectively joined to the vibrating arm portions of the diaphragm 201, and perform repetitive vibrations (repetitive motions) in the rotation direction.

Next, the operation of this embodiment will be described. FIG. 2 is a diagram for explaining an operation state of the configuration shown in FIG. 1 and 2, when a drive signal is supplied between the pedestal 200 and the diaphragm 201, the input drive signal is applied to each of the driving piezoelectric elements 202a and 202b, and the drive signal is applied by applying the input drive signal. The piezoelectric elements 202a and 202b vibrate. This vibration causes the surfaces of the driving piezoelectric elements 202a and 202b on the pedestal 200 side and the surface on the vibration plate 201 side to vibrate in directions different from each other in the X-axis direction by 180 degrees. As shown in FIGS. 2A and 2B, the diaphragm 201 vibrates while being repeatedly rotated at a delicate angle on the XY plane around the center of gravity of the plate. Further, an angular velocity detecting piezoelectric element 203 joined to the vibrating arm of the diaphragm 201
a to 203d perform repetitive vibration in the rotation direction. Due to this repetitive vibration, the piezoelectric elements 203a, 2
Numerals 03d vibrate so that, when the angular velocity detecting piezoelectric element 203a moves away from the center line of the diaphragm 201 in the Y-axis direction as shown in FIG. 2A, the angular velocity detecting piezoelectric element 203d also moves away. Further, as shown in FIG. 2B, when the angular velocity detecting piezoelectric element 203a approaches, the angular velocity detecting piezoelectric element 203d vibrates so as to approach. Similarly, when the angular velocity detecting piezoelectric elements 203b and 203c are separated from the center line of the diaphragm 201 in the Y-axis direction as shown in FIG. 203c also vibrates away. Then, as shown in FIG.
When 3b approaches, the piezoelectric element 203c for angular velocity detection also vibrates so as to approach.

The piezoelectric element 203a for detecting angular velocity in this portion
When the angular velocity ω is applied during the vibration of
Coriolis force acts on 1 and the vibrating arm bends. That is,
The Coriolis force can be detected from the detection signals of the angular velocity detecting piezoelectric elements 203a to 203d. This detection signal is subjected to arithmetic processing, and the angular velocity ω is detected with high accuracy.

In this embodiment, the vibrating plate 201 is provided with a vibrating arm one by one. However, a plurality of vibrating plates 201 are provided, and a piezoelectric element for detecting angular velocity is arranged to detect Coriolis force with high sensitivity. You can do it.

[0018]

As is apparent from the above description, according to the angular velocity detecting device of the first and second aspects, the driving piezoelectric element vibrates by the driving signal supplied to the pedestal and the diaphragm, and the angular velocity The detection piezoelectric element vibrates while repeatedly rotating at an angle on the XY plane centering around the center of gravity of the diaphragm. The vibrating arm is bent by the action of the Coriolis force when the angular velocity is applied during the vibration, and the angular velocity detecting element outputs a detection signal corresponding to the Coriolis force. That is, the vibrating body vibrates in the direction perpendicular to the direction in which the Coriolis force is generated, and its precise arrangement is not required, and the frequency of the driving signal depends only on the driving element and is not affected by the mechanical resonance of the diaphragm. For,
There is an effect that trimming for adjustment is not required, a highly accurate detection value can be reliably obtained, and the assembling work is facilitated, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of an angular velocity detecting device according to the present invention.

2A is a plan view showing an operation state of the configuration shown in FIG. 1; FIG. 2A is a plan view showing an operation state in which the piezoelectric element for angular velocity detection is separated; FIG. 2B is a plan view showing an operation state in which the piezoelectric element for angular velocity detection approaches;

FIG. 3 is a perspective view showing a configuration of a conventional angular velocity detecting device.

FIG. 4 is a perspective view showing an operation state of the conventional example shown in FIG. 3;

FIG. 5 is a block diagram showing a signal processing circuit in a conventional example.

[Explanation of symbols]

 200 pedestal 201 diaphragm 202a, 202b driving piezoelectric element 203a-203d angular velocity detecting piezoelectric element

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01C 19/56 G01P 9/04

Claims (2)

(57) [Claims] 1. A driving device having a thickness-shear vibration mode between a pedestal and a diaphragm, wherein the surface on the pedestal side and the surface on the diaphragm side vibrate in the X-axis direction and in directions different by 180 degrees by a drive signal. At least one set of angular velocity detecting elements is joined and arranged on a vibrating arm provided symmetrically with respect to the center of the diaphragm, and supplied to the pedestal and the diaphragm. The driving signal causes the angular velocity detecting element to rotate around the vicinity of the center of gravity of the diaphragm,
The vibrating arm is repeatedly rotated and vibrated at an angle on the Y plane, and the vibrating arm is bent by the action of the Coriolis force when the angular velocity is applied during the vibration. The angular velocity detecting element outputs a detection signal corresponding to the Coriolis force. An angular velocity detection device characterized in that: 2. The angular velocity detecting device according to claim 1, wherein a piezoelectric element is used as the driving element and the angular velocity detecting element.