JP2699603B2 - Angular velocity sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gyroscope, and particularly to an angular velocity sensor using piezoelectric element vibration.

2. Description of the Related Art Conventionally, as an inertial navigation device using a gyroscope, a mechanical rotary gyroscope is mainly used as a method for finding the direction of a moving object such as an airplane or a ship.

Although a stable azimuth can be obtained, the apparatus is large-scale because it is a mechanical type, the cost is high, and it is difficult to apply the apparatus to equipment for which miniaturization is desired.

On the other hand, there is a vibration type angular velocity sensor that detects a "Coriolis force" from a detection element vibrated by vibrating an object without using a rotational force. Many are of a structure that employs piezoelectric and electromagnetic mechanisms. In these, the motion of the mass constituting the gyro is not a constant-speed motion but a vibration. Therefore, when an angular velocity is applied, the Coriolis force is generated as a vibration torque having a frequency equal to the frequency of the mass. The principle of the vibration type angular velocity sensor is to measure the angular velocity by detecting the vibration caused by the torque, and many sensors using a piezoelectric body have been devised. (Journal of the Japan Society for Aeronautical and Space Sciences, vol.23, no.257, 339
The conventional angular velocity sensor based on the above principle is the second
It is as shown in the figure. That is, the detecting piezoelectric element 1
And the driving piezoelectric element 2 are orthogonally connected by a joining member 6 and joined to the tuning fork structure by the electrode block 3. The tuning fork structure is supported by a support rod 4 and fixed to a base 5.
Electrical wiring is connected from the lead pin 8 to the driving piezoelectric element 2 via the lead wire 7d, and from the lead pin 8 via the holding plate 9 to the detecting piezoelectric element 1 via the lead wire 7e.

In order to operate the conventional angular velocity sensor configured as described above, first, the surfaces facing each other for driving the pair of driving piezoelectric elements 2 are used as a common electrode, and an alternating current signal is applied between each surface and the outer surface. multiply. The driving piezoelectric element 2 to which the signal is applied is a so-called tuning fork vibration which starts symmetrical vibration around the electrode block 3, and when an angular velocity is applied thereto, a "Coriolis force" is generated and the angular velocity can be detected.

By holding one end of the lead wire 7e at a position substantially perpendicular to the surface of the detecting piezoelectric element 1 by the holding plate 9, inhibition of tuning fork vibration by the lead wire 7e is suppressed.

Problems to be Solved by the Invention An angular velocity sensor disclosed in Japanese Patent Application No. 1-95719 has been invented with a configuration based on the above principle, but has the following problems.

The length and diameter of the lead wire 7e are determined so that the natural frequency of the lead wire 7e is about 3 kHz or more, so that resonance does not occur at a drive frequency of about 1 kHz of the angular velocity sensor.
Also, wires are used to prevent disconnection. However, if the wires are loose or the shape becomes close to a circle, the natural frequency of the lead wire 7e decreases, which easily affects the driving of the sensor, and also directly affects the vibration of the piezoelectric element 1 for detection. Therefore, there is a problem that the final output fluctuates.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a stable angular velocity sensor having a final output without the influence of a lead wire.

Means for Solving the Problems In order to achieve the above object, the present invention provides a driving piezoelectric element, a detecting piezoelectric element, and stacking and joining the driving piezoelectric element and the detecting piezoelectric element such that the vibration directions are orthogonal to each other. A first joining member to be joined, a second joining member joining the pair joined in this way to a tuning fork structure, a support member supporting the tuning fork structure, and a base member fixing the supported tuning fork structure. Electrical connection to the detecting piezoelectric element, the lead wire is not directly connected to the electrode on the detecting piezoelectric element from the lead pin, but the lead pin is firstly connected to the first joining member by an adhesive or the like. And then connected to electrodes on the detecting piezoelectric element.

Effect The angular velocity sensor of the present invention having the above-described configuration can shorten a line segment by mechanically fixing the intermediate portion of the lead wire electrically connected to the detecting piezoelectric element to the first joining member, The natural frequency becomes sufficiently high, and the length of the lead wire becomes short, which reduces the change in shape and variation, and suppresses the fluctuation of the natural frequency. A stable angular velocity sensor can be obtained.

Embodiment FIG. 1 is a structural view showing an embodiment of an angular velocity sensor according to the present invention.
The same numbers are given. As shown, the detecting piezoelectric element 1
Member 6 in which the driving piezoelectric element 2 is a first joining member
Are joined so that the vibration directions are orthogonal to each other. A pair of the joined elements is joined to a tuning fork structure by an electrode block 3 serving as a second joining member, and fixed to a base 5 by a support rod 4. Electrical connection is made from the lead pins 8 embedded in the base 5 to the driving piezoelectric element 2 via lead wires 7a, and the holding plate 9
Member 6 with lead wire 7b from lead pin 8 held in
After being mechanically fixed with an adhesive or the like, it is connected to the detecting piezoelectric element 1 by a lead wire 7c. Lead wire 7b and lead wire 7c
Is a single lead wire, the middle of which is mechanically fixed. Since there is almost no relative vibration between the joining member 6 and the point where the lead wire 7c of the detecting piezoelectric element 1 is connected, the sensing piezoelectric element 1 side is located from the portion of the lead wire 7c bonded and fixed to the joining member 6. The effect on driving is negligible. The effect on the driving of the lead wire is as follows.
It is sufficient to consider only the effect of the portion of the lead wire 7b from the lead wire 7b to the holding plate 9. Since the connecting point of the lead wire 7b to the tuning fork structure sensor element is the joining member 6 and not the detecting piezoelectric element 1, the length from the joining member 6 of the lead wire 7b to the holding plate 9 is shown in FIG. Even if it is shorter than the lead wire 7e, the vibration of the detecting piezoelectric element 1 is not hindered. Since the line segment is shortened as the lead wire 7b and its natural frequency is set to 5 kHz, it can be largely separated from the drive frequency of 1 kHz, and the natural frequency changes due to the change in shape and dispersal of this lead wire. Even if it fluctuates, it does not become smaller than 3 kHz and has little effect on driving. Therefore, an angular velocity sensor having a stable final output can be obtained.

Effect of the Invention As is apparent from the above description, according to the present invention, the lead wire electrically connected to the detecting piezoelectric element is bonded and fixed to the joining member of the sensor element at the intermediate portion, whereby the lead wire is connected. It can be shortened, the natural frequency becomes sufficiently high, and the fluctuation of the natural frequency due to the change of the shape of the lead wire or the variation can be suppressed. Therefore, an angular velocity sensor having a stable final output can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing the structure of an angular velocity sensor according to one embodiment of the present invention, and FIG. 2 is a schematic perspective view showing the structure of a conventional angular velocity sensor. 1 ... piezoelectric element for detection, 2 ... piezoelectric element for driving, 3 ...
Electrode block (second joining member), 4 ... support rod, 5 ...
… Base, 6 …… joining member (first joining member), 7a, 7b,
7c …… Lead wire.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Susumu Sakamoto, Inventor 1006, Kazuma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Mamoru Matsuda 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-229023 (JP, A) JP-A-2-272318 (JP, A) JP-A-2-306110 (JP, A) JP-A-1-120615 (JP, U) JP-A-64-10617 (JP, U)

Claims (1)

(57) [Claims] The present invention relates to a driving piezoelectric element, a detecting piezoelectric element, a first joining member for stacking and joining the driving piezoelectric element and the detecting piezoelectric element so that their vibration directions are orthogonal to each other, and A second joining member for joining a pair of the obtained elements to a tuning fork structure, a support member for supporting the tuning fork structure on a base, a signal input / output lead pin embedded in the base, and the other end of the lead pin And a holding plate held on the piezoelectric element for detection, the electrical connection to the piezoelectric element for detection, the electrode on the piezoelectric element for detection via a mechanically fixed portion from the lead pin to the first joining member An angular velocity sensor performed by a connected lead wire.