JPH04332814A - Manufacture of anglular velocity sensor - Google Patents

Abstract

PURPOSE:To improve detection sensitivity of an anglular velocity sensor by correcting mismatched vibration of two arms caused by a relative fluctuation in piezoelectric constants, placed positions, etc., of respective driving piezoelectric elements in addition to unbalance in shape of a vibrator. CONSTITUTION:In manufacturing an angle speed sensor exhibiting an approximate tuning fork shape as a whole, while both arms 1,2 are vibrated by respective driving piezoelectric elements 6,7 attached to the two arms 1,2, an output from a detecting piezoelectric element 5 is monitored, while ultraviolet ray hardening adhesive 11 is added to at least one of the arms to adjust vibration mass.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is an orthogonal three-dimensional coordinate system in which two arms extending parallel to each other in the Z-axis direction at intervals in the Y-axis direction are excited while being excited in the Y-axis direction. , relates to a method for manufacturing an angular velocity sensor that has a substantially tuning fork shape as a whole and detects angular velocity based on the Coriolis force generated in the X-axis direction when rotated around the Z-axis. This effectively prevents a decrease in angular velocity detection sensitivity caused by mutual variations in shape and size, variations in the mounting positions of the driving piezoelectric elements on the respective arms, and the like.

0002

[Prior Art] Rotary gyroscopes have traditionally been widely used as a means of detecting the moving direction of objects, but in recent years, due to the increasing demand for consumer electronics, small and inexpensive vibrating gyroscopes have been developed. In other words, angular velocity sensors are attracting attention.

An example of a known angular velocity sensor that generates a Coriolis force when an angular velocity is generated under vibration of an object is shown in a perspective view in FIG. 2, for example.

[0004] In this orthogonal three-dimensional coordinate system, two arms 1 and 2 extend parallel to each other in the Z-axis direction at a predetermined interval in the Y-axis direction, and both arms 1 and 2 A vibrator 4 consisting of a base 3 whose base ends are interconnected is provided with a detection piezoelectric element 5 protruding from the base 3 in the X-axis direction, and a driving piezoelectric element 5 is provided on the outer surface of each of the two arm parts. This is an angular velocity sensor that has an approximately tuning fork shape as a whole and is made up of a plurality of piezoelectric elements 6 and 7 arranged therein. be done.

[0005] In such an angular velocity sensor, by applying an alternating current voltage to the drive piezoelectric elements 6 and 7 attached to the outer surfaces of the arms 1 and 2, the arms 1 and 2 are caused to vibrate symmetrically in the Y-axis direction. , while maintaining that vibration state, vibrator 4
When rotated around the Z-axis at an angular velocity ωZ, Coriolis forces FX in opposite directions in the X-axis direction are generated on each of the arms 1 and 2, which are moving at a velocity V, at a certain moment.

[0006] Here, the speed V of the arms 1 and 2 changes alternately, and the Coriolis force FX is generated modulated by the excited frequency, so the vibrator 4 moves along the Z axis. It will torsionally vibrate around it, and the torsion angle at that time is
Coriolis force FX is proportional to angular velocity ωZ.

Therefore, in this angular velocity sensor, the torsional vibration is converted into a bending vibration of the detection piezoelectric element 5, for example, a bimorph element, which protrudes in the X-axis direction and is fixed to the case or other parts, and the bimorph is The electric charge generated by the element is extracted as a voltage.

[0008]

[Problems to be Solved by the Invention] According to such an angular velocity sensor, when the driving piezoelectric elements 6 and 7 vibrate the arm parts 1 and 2, the vibration amplitude of both the arm parts 1 and 2 is always kept constant. In the actual manufacture of the angular velocity sensor, it is necessary to vibrate both of them accurately and symmetrically.
piezoelectric characteristics, the mounting positions of the drive piezoelectric elements 6 and 7 with respect to the respective arm parts 1 and 2, the shape and dimensions of both arm parts 1 and 2,
Since it is virtually impossible to match the mass etc. with high precision, the unbalanced vibrations of both arms 1 and 2 will cause unnecessary vibrations in the base 3, and as a result, The detection piezoelectric element 5 also detects unnecessary vibrations and outputs a signal, so that the situation appears as if the Coriolis force FX is being detected even though the angular velocity ωZ is actually zero. That is, there is a problem in that an offset output is generated, resulting in a decrease in the S/N ratio and, ultimately, in detection sensitivity.

In order to solve this problem, as disclosed in Japanese Patent Application Laid-Open No. 62-250309, each arm is cut by cutting the free end of one of the arms using a laser. A method has been proposed to improve the detection sensitivity of angular velocity by eliminating the difference in sensitivity to acceleration between the Another problem is that it requires a lot of skill, and furthermore, it is impossible to recreate the arm once it has been cut.

The present invention solves all of the problems of the prior art, and achieves extremely high detection sensitivity without requiring an expensive device such as a laser cutting device or skill to operate the device. It is an object of the present invention to provide a method for manufacturing an angular velocity sensor that can be effectively improved and that can be repeatedly adjusted.

[0011]

[Means for Solving the Problems] In the method of manufacturing an angular velocity sensor of the present invention, when manufacturing an angular velocity sensor having an approximately tuning fork shape as a whole, the arm With the part excited,
While observing the output from the detection piezoelectric element installed on a surface perpendicular to the mounting surface of the drive piezoelectric element, add ultraviolet curing adhesive to the required position of at least one arm, and then This is to adjust the mass and the vibrating mass including the mass of the drive piezoelectric element disposed there.

0012

[Operation] In the manufacturing method of the present invention, the mutual
Variations in shape, dimensions, mass, etc., piezoelectric characteristics, mounting position, etc. of each drive piezoelectric element, etc.
By correcting it by adding a vibrating mass to the arm at the final stage of the sensor manufacturing process, the offset output caused by these variations can be significantly reduced, and the sensitivity of Coriolis force and, therefore, angular velocity detection can be improved. It can be greatly improved.

[0013] Incidentally, the addition of the vibrating mass here can be carried out by dropping or applying the required amount of ultraviolet curable adhesive onto an arbitrary position using, for example, a precision dispenser, and irradiating the adhesive with ultraviolet rays. Therefore, compared to the conventional technology using a laser cutting device, equipment costs can be significantly reduced, and skill for the work can be almost eliminated.

Moreover, here, even after dropping or applying the ultraviolet curable adhesive, as long as it is not irradiated with ultraviolet rays,
Since the adhesive can be easily removed using a solvent or the like, readjustment can be easily performed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the invention,
In the figures, parts equivalent to those described in the prior art are indicated by the same numbers.

That is, in the figure, 1 and 2 indicate arms that extend parallel to each other in the Z-axis direction of the three-dimensional coordinate system and are located at a predetermined interval in the Y-axis direction, and 3 indicates , the right end of the figure shows a base that integrally connects both arm parts 1 and 2.

Reference numeral 4 indicates a vibrator consisting of arm portions 1 and 2 and a base portion 3, and this vibrator 4 is connected to the case and other parts by means of a detection piezoelectric element 5 provided protruding from the base portion 3 in the X-axis direction. It is fixed to the base part 8 of.

Furthermore, 6 and 7 indicate respective driving piezoelectric elements attached to the outer surfaces of the respective arm portions 1 and 2;
These drive piezoelectric elements 6 and 7, which can be constructed from bimorph layers, can be moved by applying an alternating current voltage thereto, so that both arm parts 1 and 2 can be rotated by 180 degrees with respect to the Z axis with the base 3 as a fulcrum. It functions to cause symmetrical vibration with a phase difference of °.

In addition, as shown in the figure, each of the arm parts 1 and 2 has a tip weight 9 at each free end thereof, which increases the sensitivity to the Coriolis force. The vibrator 4 is integrally molded from a metallic elastic material having a high Young's modulus, such as Elinvar alloy.

In this embodiment, in a semi-finished sensor having the above-mentioned configuration, both arm parts 1
. A precision dispenser 12 is used to apply a drop onto an arbitrary position on at least one arm (arm 1 in the figure). When the amount of the dripping reaches an appropriate amount, the dimensions, shapes, and masses of both arm parts 1 and 2, piezoelectric constants, dimensions, shapes, arrangement positions, and other unbalances of piezoelectric elements 6 and 7 for both drives are unbalanced. is effectively modified, and the angular velocity ωZ
When the offset voltage is at its minimum under the condition where harden.

By the way, in the case of adding the vibrating mass in this way, the ultraviolet curable adhesive 11 used is:
It is preferable that the adhesive 11 has thixotropy (non-flowability), and the above-mentioned imbalance can be corrected by adding mass by increasing or decreasing the dripping amount of the adhesive 11, as well as changing the dripping position of the adhesive 11. can be carried out over a fairly wide range by appropriately selecting the range from the proximal end of the arm to the free end surface, and/or by mixing filler with the adhesive 11.

Therefore, according to the angular velocity sensor manufactured in this way, the shape, size, mass,
Even if there are variations in the piezoelectric characteristics, dimensions, shapes, placement positions, etc. of the piezoelectric elements 6 and 7 for both drives, both arm parts 1 and 2 can be moved under the action of the additional mass created by curing the adhesive 11. It becomes possible to vibrate symmetrically with high precision, and as a result, the offset output when the angular velocity ωZ is zero can be extremely effectively reduced, and the detection sensitivity of the angular velocity ωZ can be greatly improved.

[0023]

[Effects of the Invention] As is clear from the above, according to the present invention, in addition to the shape imbalance of the vibrator, the piezoelectric constant, size, shape, and arrangement of each drive piezoelectric element can be The detection sensitivity of the angular velocity sensor can be improved by correcting mismatched vibrations of the arms due to relative variations in position, etc. by adding a vibrating mass to at least one arm when the sensor is near completion. can be greatly improved.

Furthermore, since the additional mass here is brought about by irradiating the ultraviolet ray curing adhesive with ultraviolet rays, the equipment cost required to add the additional mass to the vibrating mass can be kept sufficiently low. At the same time, the skill required for the work can be made almost unnecessary.

Furthermore, before irradiation with ultraviolet rays, the dripped or applied adhesive on the arm can be removed using, for example, a solvent, making it possible to repeatedly adjust the vibrating mass.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the invention.

FIG. 2 is a perspective view illustrating a conventional angular velocity sensor.

[Explanation of symbols]

1, 2 Arm part 3 Base 4. Oscillator 5 Piezoelectric element for detection 6,7 Drive piezoelectric element 8 Base part 9 Tip weight 11 Ultraviolet curing adhesive 12 Precision dispenser 13 Ultraviolet irradiator

Claims (1)

[Claims] Claim 1: Within an orthogonal three-dimensional coordinate system, two arms extending parallel to each other in the Z-axis direction at intervals in the Y-axis direction are excited in the Y-axis direction while moving around the Z-axis. When manufacturing an angular velocity sensor that has an almost tuning fork shape as a whole and detects angular velocity based on the Coriolis force generated in the X-axis direction when rotated, both arms are While the arm part is being excited, and while observing the output from the detection piezoelectric element installed on the surface perpendicular to the driving piezoelectric element, add ultraviolet curing adhesive to the arm part to reduce the vibration mass. A method of manufacturing an angular velocity sensor, characterized by performing adjustment.