JP3036137B2 - Angular velocity sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gyroscope and an angular velocity sensor using a vibration member.

[0002]

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

[0003] Although these can obtain a stable orientation, they are mechanical, so that the apparatus is large, the cost is high, and it has been difficult to apply them to equipment for which miniaturization is desired.

On the other hand, there is a vibration type angular velocity sensor which detects Coriolis force from a vibrating sensing element by vibrating an object without using a rotational force. Many are of a structure that employs piezoelectric and electromagnetic mechanisms. These are vibrations in which the motion of the mass constituting the gyro is not a constant speed motion. 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. Measuring the angular velocity by detecting the vibration due to the torque is the origin of the vibration type angular velocity sensor, and many sensors using a piezoelectric body have been devised in particular (Journal of the Japan Society for Aeronautical and Space Sciences, Vol. 23, No. 257, 239). −
350P).

[0005]

An angular velocity sensor having a configuration based on the above principle has been invented, but has the following problems.

In the tuning fork vibration type sensor, there is a sensor having a structure in which a detection unit and a drive unit are integrated with a metal plate and bent. When a temperature change is applied, the detection unit and the drive unit move at a bent portion, and the orthogonal angle changes. Therefore, these factors cause an offset output variation in a wide temperature range. Few sensors could be obtained.

Further, in order to obtain high accuracy without changing the orthogonal angle, a metal block is cut out and manufactured.

[0008] These do not change the orthogonal angle and have excellent temperature characteristics, but have drawbacks such as high manufacturing cost.

The present invention has been made in view of the foregoing, and has as its object to obtain an inexpensive angular velocity sensor having excellent temperature characteristics over a wide temperature range.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a tuning fork vibrating member by connecting a vibrating member having a driving element and a detecting element arranged substantially orthogonally to each other on the driving element side. And the above-mentioned vibrating member is bent at a substantially right angle by a slit provided from a widthwise end toward an intermediate portion so as to be staggered in a longitudinal direction at a substantially central portion of a flat metal plate. This is configured by attaching piezoelectric elements to both sides of the bent portion.

[0011]

According to the above configuration, when the driving element is vibrated,
Since the center of the driving element and the center of the sensing element can be aligned on a straight line, when the tuning fork is vibrated, the sensing element is balanced in weight and does not twist and vibrate. Even if it has characteristics, the sensing element does not twist and vibrate, so that an angular velocity sensor with a small output offset signal fluctuation over a wide temperature range without generating unnecessary signal components from the sensing element portion can be obtained.

[0012]

1 and 2 are structural views showing an embodiment of an angular velocity sensor according to the present invention. A tuning fork vibration system will be described below.

First, the structure of the vibration part of the sensor will be described. In FIG. 2, reference numerals 1 and 2 denote vibration members, and the vibration members 1 and 2 are flat metal plates 3 mainly made of Fe and Ni.
4 are bent substantially at right angles by slits provided from the ends in the width direction toward the intermediate portion so as to be staggered in the longitudinal direction at substantially the center, and the bent portions 3a, 4
The piezoelectric elements 5 and 6 provided with Ag electrodes on both sides of the piezoelectric ceramic are attached to both sides of the element a. The upper and lower portions of the vibrating members 1 and 2 serve as detecting elements, and the lower portions of the vibrating members 1 and 4a serve as driving elements. The detecting elements and the driving elements are arranged substantially orthogonal to each other.

The piezoelectric elements 5 and 6 include vibration members 1 and 2
The piezoelectric elements 5 and 6 are electrically connected to each other by bonding with an epoxy adhesive.

Next, as shown in FIG. 1, the pair of left and right vibrating members 1 and 2 obtained as described above is held in parallel by a metal block 7 to constitute a tuning fork vibrating member. Have been. The metal block 7 has a hole at the center and is supported by a support rod 8.

The vibrating members 1 and 2 are connected to the electrode block on the driving element side. The support rod 8 is fixed to the terminal base 9.

The terminal base 9 is mainly composed of Fe, and the lead terminals 10, 11, 12, 13, 14, 15 and the support rod 8 are provided.
And insulating glass 16, 17, 18, 19, 20, 21,
22 are implanted. Lead terminals 10, 12,
Reference numeral 13 denotes a terminal for guiding electric signals from the two piezoelectric elements 5 and 6 to the outside.

The lead wires 23, 24, 25, 2
Reference numeral 6 is for connecting the piezoelectric elements 5 and 6 to the lead terminals 10, 12, and 13.

Reference numeral 27 denotes a can cap 27 mainly composed of Fe.
Thus, the outer peripheral edge of the terminal base 9 is joined by welding to form an angular velocity sensor.

The outline of the operation of the angular velocity sensor of the present embodiment configured as described above will be described below.

First, in order to drive the tuning fork vibrating member, an AC signal is applied to one of the piezoelectric elements 6 on the driving element side provided on the vibrating member 1 or 2, for example, to the piezoelectric element on the lead terminal 13 side. The element 6 starts vibrating, and the vibrating members 1 and 2 start symmetric tuning fork vibration around the support rod 8.
In this tuning fork vibration, when an angular velocity is applied to a vibrating system, a physical force (Coriolis force) acts, and an angular velocity signal is detected by the piezoelectric element 5 on the detecting element side provided on the vibration members 1 and 2. be able to. Generally, a tuning fork having tuning fork vibration
The piezoelectric elements 5 and 6, which are constituent materials of the tuning fork, and the vibrating members 1 and
It is determined by overall performance such as 2.

Next, based on the above embodiment, the result of comparing the characteristic evaluation with the conventional example will be described. In the comparative conventional angular velocity sensor, the detection unit and the driving unit are the same metal plate, and are bent at the side of the metal plate.

FIG. 3 compares the temperature-offset output characteristics of the present invention and the conventional example. According to FIG.
When a temperature change of −40 ° C. to 85 ° C. was given and the temperature offset change was compared, it was found that the example of the present invention had a smaller change in the offset output value of about 1/5.

Further, the above-described embodiment and the conventional angular velocity sensor are compared with each other in terms of sensor sensitivity and offset output by -4.
When 100 cycles of repeated temperature shocks were applied at a temperature of 0 ° C. to 85 ° C., and the characteristics before and after were compared, the example of this example showed a sensitivity change of に お い て within the range of the repeated temperature shocks.
Hereinafter, an offset output change of 1/5 or less was obtained.

Although the present invention has been described with reference to a sensor having a structure in which the central portion of the tuning fork vibration member is held and supported by a metal block as an embodiment, the central portion of the tuning fork is a U-shaped tuning fork vibration member. The same effect can be obtained even in a tuning fork structure integrated with no metal block 7.

[0026]

As described above, according to the present invention, when the tuning fork is vibrated, the sensing element portion has a good weight balance at the center, so that the sensing element does not twist and vibrate, and the sensing element does not vibrate. The unnecessary vibration component is reduced, and a stable angular velocity sensor with no characteristic change over a wide temperature range and a sudden temperature change can be obtained. Furthermore, since the metal plate can be bent, cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an angular velocity sensor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a vibration member of the sensor.

FIG. 3 is a temperature-offset output characteristic diagram of a sensor of the present invention and a conventional sensor.

[Explanation of symbols]

 1, 2 vibrating member 3, 4 metal plate 3a, 4a bent portion 5, 6 piezoelectric element

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Toshihiko Ichise 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. No. (72) Inventor Junsei Yoshida 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-163611 (JP, A) JP-A-61-180107 (JP, A) ) Actually Opened Hei 2-88109 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01C 19/56 G01P 9/04

Claims (1)

(57) [Claims] A tuning fork vibrating member is formed by connecting a vibrating member having a driving element and a detecting element arranged substantially orthogonally to each other on the driving element side, and the vibrating member is substantially formed of a flat metal plate. Structurally formed by slitting at approximately the right angle with slits provided from the widthwise end to the middle so that they are staggered in the longitudinal direction at the center, and pasting piezoelectric elements on both sides of the bent part Angular velocity sensor.