JPH03276012A - angular velocity sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

BACKGROUND OF THE INVENTION Conventionally, a mechanical rotary gyro has been mainly used as an inertial navigation device using a gyroscope to determine the direction of a moving object such as an airplane or a ship.

Although this method can provide stable orientation, since it is mechanical, the device is labor intensive and expensive, and it is difficult to apply it to equipment that is desired to be miniaturized.

On the other hand, there is a vibration-type angular velocity sensor that vibrates an object without using rotational force and detects the "Coriolis force" from the vibrated sensing element. Many of these structures employ piezoelectric and electromagnetic mechanisms. In these cases, the mass that makes up the gyro does not move at a constant speed, but instead vibrates. Therefore, when angular velocity is applied, the Coriolis force is
It is generated as a vibration torque with a frequency equal to the frequency of the mass. The principle of a vibration-type angular velocity sensor is to measure angular velocity by detecting vibrations caused by this torque, and in particular, many sensors using piezoelectric materials have been devised (Journal of the Japan Society for Aeronautics and Astronautics, Vol. 23, No. 267, 339). -36
0 pages).

FIG. 2 shows the structure of an angular velocity sensor based on the above principle. In FIG. 2, 1 is a detection piezoelectric element, 2 is a coupling member, and 3 is a drive piezoelectric element.
A sensor element is constructed by joining a detection piezoelectric element 1 and a detection piezoelectric element 1 to a joining member 2 so as to be orthogonal to each other. A tuning fork element is constructed by joining this pair of sensor elements to an elastic coupling member 4 at the end of the driving piezoelectric element 3 so as to form a tuning fork structure. Further, this tuning fork element is mounted on a base 6 while being supported by a support pin 5 whose one end is connected to approximately the center of the elastic coupling member 4.

Reference numeral 7 denotes a driving electrode formed to face both sides of the driving piezoelectric element 3; 8 denotes a signal leader line formed on the driving piezoelectric element 3 so as to be disposed outside the driving electrode 7; This is for drawing out leads from the electrodes of the detection piezoelectric element 1.

Reference numeral 9 denotes a lead wire that connects the driving electrode 7, the signal lead wire 8, and the lead pin 10 implanted in the base 6.

To operate the conventional angular velocity sensor configured as described above, first, in order to drive the pair of drive piezoelectric elements 3, the opposing inner surfaces are used as a common electrode, and the outer surfaces are driven respectively. An alternating current signal is applied between the electrode 7 for use. The drive piezoelectric element 3 to which the signal has been applied begins to vibrate symmetrically about the elastic coupling member 4 . This is what is called tuning fork vibration.

When a rotation with an angular velocity ω is applied to the detection piezoelectric element 1 which is vibrating at a speed V, a "Coriolis force" is applied to the detection piezoelectric element 1.
occurs. This "Coriolis force" is perpendicular to the velocity V and has a magnitude of 2m+17ω. Since the tuning fork is vibrating, if one of the sensing piezoelectric elements 1 is vibrating at a speed of V at a certain point, the other sensing piezoelectric element 1 is vibrating at a speed of -V, resulting in the "Coriolis force' is −2 mVω. Coriolis forces acting in opposite directions act on the pair of detection piezoelectric elements 1, causing them to deform in opposite directions, and charges are generated on the surfaces of the elements due to the piezoelectric effect. The pair of sensor elements are wired so that charges generated by the "Coriolis force" are added to each other.

Therefore, even if a translational motion other than angular velocity is applied to the sensor, charges of the same polarity will be generated on the surfaces of the pair of detection piezoelectric elements 1, so that they will cancel each other out and no output will be produced.

Here, Ma is the speed caused by tuning fork vibration, and the tuning fork vibration speed is Ma=v −5 inωot vo: tuning fork vibration speed amplitude ω. :If it is the angular period of the tuning fork vibration, then the "Coriolis force" is FC=21 tomao・ω−! ilnωot, the angular velocity ω and the tuning fork vibration velocity ma. It is proportional to , and becomes a force that deforms the detection piezoelectric element 1 in the plane direction. Therefore, the surface charge amount Q0 of the detection piezoelectric element 1 is Qcoc''la −to ·Sin ωot, and if the tuning fork vibration velocity amplitude V is controlled to be constant, then Qcocω ·sin (L+ot). , the amount of surface charge Q generated on the detection piezoelectric element 1 is obtained as an output proportional to the angular velocity ω.

Also, the driving electrode 5a on the driving piezoelectric element 3.

Charges are generated in 6b according to the deformation of the drive piezoelectric element 3, but since the drive electrodes 6a and 6b are symmetrical in shape and have the same area, the generated charges are equal. , the generated charge is canceled by signal processing using differential input.

Problems to be Solved by the Invention The angular velocity sensor having the above configuration has the following problems.

When connecting wires using the wire bonding method, a backup device is required to hold the element. Especially when realizing an angular velocity sensor that uses a parallel bimorph for a piezoelectric bimorph element for detection, etc., the wire bonding method It was difficult to automate. Also, the wire
Because its thinness is finite, it always inhibits vibration.

Therefore, this has also been an obstacle to realizing stable driving of tuning fork vibration.

The present invention has been made in view of this problem, and an object of the present invention is to obtain an angular velocity sensor that can solve these problems.

Means for Solving the Problems In order to solve the above problems, the present invention uses electrodes made of conductive paste to connect the electrodes of the drive piezoelectric element and the detection piezoelectric element electrodes.

Effect: The above-mentioned configuration facilitates mass production, stabilizes output, and improves vibration resistance.

Embodiment FIG. 1 is a structural diagram showing an embodiment of an angular velocity sensor according to the present invention. In FIG. 1, 11 is a piezoelectric bimorph element for detection, 12 is a coupling member, and 13 is a piezoelectric bimorph element for drive. A υ sensor element is constructed by joining them orthogonally to each other. Then, the ends and portions of the pair of sensor elements are fitted into the recesses of the coupling member 14 made of ceramic at the ends of the driving piezoelectric bimorph element 13 so as to form a tuning fork structure. By joining them together, a tuning fork element is constructed.

Furthermore, this tuning fork element is mounted on the base 16 while being supported by a support pin 16 whose one end is connected to approximately the center of the coupling member 14.

Reference numeral 17 indicates a drive electrode formed to face both sides of the drive piezoelectric bimorph element 130, and 18 indicates this drive electrode 17.
The driving piezoelectric bimorph element 1 is arranged outside the
3 is used to lead out the lead from the electrode of the piezoelectric bimorph element 11 for detection.

Reference numeral 19 denotes a lead wire that is implanted in the driving electrode 17, the signal lead line 18, and the pin 16, or connects the lead pin 2o.

Here, an extraction electrode 21 is provided on the outer surface of the coupling member 12 by baking silver paste, and this extraction electrode 21 connects the electrode of the piezoelectric bimorph element 11 for detection and the signal extraction line provided to the piezoelectric bimorph element 13 for driving. 18 are connected.

A lead electrode 22 is provided on the top and side surfaces of the coupling member 14 by baking silver paste, and the lead electrode 22 connects the electrode of the driving piezoelectric bimorph element 13 and the signal lead wire 18 to the single wire 19. has been done.

Note that 11a and 13a are intermediate electrodes of the piezoelectric bimorph element 11 for detection and the piezoelectric bimorph element 13 for drive, respectively.

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

The principle of angular velocity detection is the same as the conventional example, so a description thereof will be omitted.

Since the coupling member 14 is made of ceramic, an electrode for leading out the lead wire 19 from the tuning fork element can be provided from the coupling member 14.

The connection between the detection piezoelectric bimorph element 11 and the drive piezoelectric bimorph element 13 with the signal lead wire 18 and the lead wire 1
9 and the drive piezoelectric bimorph element 13 are baked using silver paste.

The silver paste is 80% silver and is a mixed bond type that uses both glass and oxide. Signal extraction M1 of piezoelectric bimorph element 11 for detection and piezoelectric bimorph element 13 for drive
In the connection with 8, there is no movable part such as a bonding wire, so stable characteristics can be obtained, and there is no need to use a connecting member provided with a conductor, so costs can be reduced.

Extraction electrode and drive piezoelectric bimorph element 1
3, there is no need for backup in the case of wire bonding, and automation becomes easy, especially when the drive piezoelectric bimorph element 13 and the like are made into parallel contacts.

Although silver conductive paste was used in this embodiment, it is not limited to silver as long as it is a conductive paste, and copper paste, carbon paste, etc. can also be used.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, according to the present invention, by making connections using conductive paste, lead wires can be almost eliminated, stable tuning fork vibration can be obtained, and output can be stabilized. Additionally, the risk of lead wire breakage is eliminated. Furthermore, it is possible to obtain an angular velocity sensor that allows fine wiring, facilitates automation, and is highly mass-producible.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an angular velocity sensor according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a conventional angular velocity sensor. 11...Piezoelectric bimorph element for detection, 12゜1
4...Coupling member, 13...Piezoelectric bimorph element for drive, 21.22...Extracting electrode.

Claims (1)

[Claims] A driving piezoelectric element and a sensing piezoelectric element are orthogonally connected to each other via a coupling member to constitute a sensor element, and a part of the electrode of the driving piezoelectric element is used as a signal line of the sensing piezoelectric element. An angular velocity sensor characterized in that the signal line and the detection piezoelectric element are connected by an electrode made of a conductive paste provided on a coupling member.