JPS59170772A - Angular velocity sensor - Google Patents

Abstract

PURPOSE:To eliminate an offset and to improve detection precision by providing a piezoelectric element on the surface perpendicular to the oscillation surface of an oscillator among flanks which support the oscillator. CONSTITUTION:When the piezoelectric elements 2a and 2b are supplied with an electric signal of frequency close to a resonance frequency, a tuning fork 4 starts oscillating. When this tuning force 4 is swiveled around an axis Z-Z, Coriolis force operates on a fitting part 5b having a surface perpendicular to the oscillation surfaces of the tuning fork 4, whose oscillations are transmitted to the fitting part 5b. At this time, the amplitude of oscillation transmitted to the fitting part 5b is proportional to an angular velocity around the axis Z-Z, so the electric signal generated between the piezoelectric elements 2c and 2d is proportional to an angular velocity around the axis Z-Z. The oscillation surfaces 4a of the tuning fork 4 are thin as compared with the area, so the oscillation mode in a direction X-X is much smaller than that in a direction Y-Y.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an angular velocity sensor that detects the angular velocity of a rotating body or the like.

[Prior art]

Conventionally, a vibrating gyroscope has been used as a sensor for detecting angular velocity. As shown in FIG. 1, this is a structure in which piezoelectric elements 2a to 2d are attached to each side surface of a prism 1, and the prism 1 is supported by support members 3a r 3b.

When a power source having a constant frequency is connected to the opposing piezoelectric elements 2a12b, the square column 1 vibrates in the zz' force direction using the supporting members 3a and 3b as nodes. This prism 1 is x −x
When rotating around the 'axis, the prism 1 also vibrates in the Y-Y' direction, and Newton's law of motion states that the vibration amplitude is proportional to the angular velocity applied to the x-x' axis. It has been analyzed based on the Coriolis force and the Coriolis force, and is well known. Therefore, the piezoelectric element 2a12b of the square column 1
Since the piezoelectric element 2C12d provided on the side surface perpendicular to the side surface on which the square column 7 is provided outputs a voltage proportional to the Y-Y' direction vibration of the prism 7, the angular velocity can be determined from this voltage value.

However, in such a conventional sensor, since the area of each face in the longitudinal direction of the prism 1 is approximately the same, the vibration modes are similar, and even when the angular velocity around the x-x' axis is not given, Since the vibration in the zz' force direction causes some vibration in the Y-Y' direction due to resonance, an offset occurs. In order to reduce this offset, it is possible to change the area ratio of the horizontal plane and the vertical plane in the longitudinal direction, but in this case, the area of one plane will be small, and the piezoelectric element will also be small, so the output It has the disadvantage that the voltage becomes small and the accuracy deteriorates. I'm jealous of cleaning up the angular velocity sensor.

In order to achieve such an object, the present invention provides a piezoelectric layer eC on a side surface of a support body that supports a vibrating body, which is perpendicular to the photographing surface of the barrel moving body.

Hereinafter, the present invention will be described in detail using drawings showing embodiments.

〔Example〕

FIG. 2 is a perspective view showing one embodiment of the present invention.
The same symbols are used for parts that are the same as those in the figure. The tuning fork (+1) in the figure is a four-piece vibrating body, and has two vibrating pieces 4a that are sufficiently thin compared to the area of the vibrating surface, and piezoelectric elements 2a and 2b are attached to each vibrating piece 4a. installed.

The tuning fork 4 is supported at two points by the support body 5. This support body is made up of 9 thin plates consisting of 5 pieces, with a support part 5a fixed to the tuning fork 4 and a mounting part 5b fixed to the mounting plate 6 h7.
The supporting part 5a and the mounting part 5b are in a right-angled relationship, and the surface of the mounting part 5b includes both the vibrating pieces 4a+4a (the Y-Y axis and the Z-Z axis in FIG. (containing plane). Piezoelectric elements 2c and 2d are attached to sides of the support body 5 that are perpendicular to the vibration plane of the tuning fork 4, that is, to both sides of the attachment portion 5b.

The operation of the sensor configured in this way is as follows.

When an electric signal having a frequency close to the resonance frequency of the tuning fork 4 is supplied to the piezoelectric element 2a12b, the fork 4 starts to vibrate. When the tuning fork 4 is rotated around the 2-2 axis, a Coriolis force acts on the mounting part 5b, which has a surface perpendicular to the vibration surface of the tuning fork 4, and the vibration of the tuning fork 4 is transmitted to the mounting part 5b. Since the amplitude of the vibration transmitted to the portion 5b is proportional to the angular velocity tr given around the Z-Z axis between the piezoelectric elements 2CI2d (this was analyzed by Coriolis), A signal is generated in proportion to the angular velocity.

In this case, the tuning fork 4 not only vibrates in the direction including the vibrating pieces 4a+4a, that is, in the Y-Yil11 direction, but also in the i
If it also has a vibration form in the n-angle x - x rl and H directions,
Even if the angular velocity around the Z-Z axis is not given, the mounting part 5
The piezoelectric elements 2C and 2dK provided at t generate an air signal, causing an offset. However, since the shape of the tuning fork 4 can be selected arbitrarily, the tuning fork 4 used in this invention is configured so that the vibrating piece 4a is thinner than the area, so that X-X The direction of the swing is Y
,, The vibration form can be made sufficiently small compared to the vibration form in the -Y direction. Therefore, the electric signal generated in the piezoelectric elements 2c+2d when the angular velocity around the 2-Z axis is not given is sufficiently smaller than the 7d signal generated when the angular velocity is given, and substantially no offset occurs.

Since no offset occurs, the piezoelectric elements 2c, 2
There is no need to reduce the area of d, and therefore the pressure fF
i, element 'lc, -2d K Since the value of the generated electric signal becomes large, detection and integration can be improved.

〔Effect of the invention〕

As explained above, the angular velocity sensor according to the present invention uses a tuning fork having a vibrator whose thickness is sufficiently thin compared to the area of vibration, and a piezoelectric element is placed on the side surface of the supporting body of the tuning fork on a surface perpendicular to the vibration surface. Since the configuration is provided with lx < , there is an effect that an offset occurs and the detection accuracy is also good.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional angular velocity sensor, and Section 2 1 is a perspective view of an angular velocity sensor according to the present invention. 2a to 2d... Piezoelectric element, 4... Tuning fork, 4a
... Vibrator, 5... Support body. Patent applicant: G-Eco Co., Ltd. Agent: Masaki Yamakawa (and one other person)

Claims (1)

[Claims] A vibrating body having a thin vibrating piece with a large vibrating surface area, a support body that supports this vibrating body, and a piezoelectric element provided on a side surface of the support body that is perpendicular to the vibrating plane of the vibrating body. Configured angular velocity sensor.