JP3270239B2 - Acceleration sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor used for attitude control of a moving body such as an automobile, an aircraft, a ship, a vehicle, and the like, and a navigation system.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting acceleration, a strain gauge type sensor in which a strain gauge is attached to a cantilever has been mainly used. An example is shown in FIG. As shown in FIG. 16, the strain gauge sensor includes a fixed portion 13, a cantilever 14, and a strain detecting resistor 15. These related prior arts are disclosed in Japanese Patent Application Laid-Open No. 61-14457.
No. 6 publication.

On the other hand, there is a sensor using a semiconductor silicon chip which is temperature-compensated for a change in temperature. However, for a wide range of acceleration, a low frequency close to DC in practical use is obtained from the bending strength of the silicon chip. It was not sufficient to detect in the full range from high acceleration to high acceleration. Therefore, it is required to form a cantilever that can sufficiently withstand impact resistance. A related technique is Japanese Patent Application No. 63-74157.

[0004]

Various acceleration sensors having the above-mentioned configuration have been proposed, but have the following problems. The acceleration sensor is mainly a sensor having a two-layer structure in which an elastic body subjected to mechanical strain is integrated with a detection unit that converts the change into an electrical change. The acceleration sensor having such a two-layer structure receives a change in the adhesive or the thermal expansion of the cantilever to which the strain detecting resistor serving as the detecting portion is attached due to a change in the external temperature. Due to various factors, the temperature drift is large, the stability of the detection operation is difficult, and the output value fluctuates due to a temperature change.

It is an object of the present invention to provide an acceleration sensor which has excellent temperature characteristics in a wide temperature range, can detect acceleration with high sensitivity and low drift.

[0006]

According to the acceleration sensor of the present invention, a desired crystal axis and a crystal blank cut out in the plane of the crystal axis are mechanically or electrically processed, and the vibrating arm is formed only by the crystal blank. A pair of substantially U-shaped tuning-fork type quartz vibrators are formed symmetrically arranged, one of which is a driving-side tuning fork and the other is a detecting-side tuning fork. Integral configuration separate for detection, ie 2
Two substantially U-shaped tuning-fork type quartz vibrators are integrally formed via a connector at a support portion which is a base of two vibrating arms so as to face each other in parallel to each other.

[0007] The binding site of the connector with respect to the support is substantially U
It is desirable to have a portion where the mechanical Q value of the character-shaped tuning-fork type quartz vibrator has a small decrease and the vibration can be transmitted effectively. For example, in the support portion, regions having a certain area including a vibrating node (the meaning of which will be described later) may be integrally formed via a connector. As described above, when the drive-side tuning fork and the detection-side tuning fork are fixed to each other with a certain area including the vibrating node generated in the support portion via the block-shaped connector, the energy confinement theory is used. In addition, the mechanical Q value of the tuning fork vibration and the mechanical transmission efficiency from the driving side tuning fork to the detection side tuning fork can be maximized. Therefore, the mechanical transmission loss in the substrate of the conventional tuning fork coupling portion can be remarkably improved, and the sensitivity of the angular velocity detection by the Coriolis force can be remarkably improved.

[0008] Even if other portions of the support portion such as the bottom surface of the support portion are connected to each other, the vibration can be transmitted from the drive side to the detection side. Therefore, the coupling portion is not limited to the above-described vibration node. is there. As described above, according to the present invention, two vibrating arms of the detection-side tuning fork are used so that one of the driving-side tuning forks maintains the driving vibration (torsional vibration) and the other detection-side tuning fork detects the Coriolis force. An electrode for extracting an electric signal of a vibration component in a direction perpendicular to a connecting direction (X-axis direction), that is, a direction of a displacement speed due to acceleration (Z'-axis direction), on a detection-side tuning fork; Accordingly, it is possible to obtain a highly accurate and inexpensive acceleration sensor with very little temperature drift.

Further, since a substantially U-shaped tuning-fork type quartz vibrator in which the vibrating arm and the supporting portion are integrally connected is used, there are no various manufacturing steps such as a piezoelectric element attaching step as in a conventional example, and the temperature is reduced. It is intended to obtain a stable acceleration sensor without variation. Hereinafter, a description will be given corresponding to each claim. Claim 1
The acceleration sensor described above cuts out in the X, Y 'plane with the Y' axis direction of the new crystal axes X, Y ', Z' rotated around the X axis of the crystal axes X, Y, Z in the longitudinal direction. Electrodes are respectively provided on the peripheral surfaces of the one and the other vibrating arms of a substantially U-shaped tuning fork-shaped quartz blank having a shape in which one and the other symmetric vibrating arms of a rectangular cross section are connected in parallel and integrally by a support portion. The first and second tuning-fork type quartz vibrators are fixed to the support portion via a connector in a state where they face each other in parallel to each other, and the first tuning-fork type quartz vibrator is connected via electrodes. By applying an AC voltage
A drive-side tuning fork for generating torsional vibrations of opposite phases displaced about the Y 'axis of one and the other vibrating arms is provided, and the second tuning-fork type quartz vibrator is connected to the first tuning fork via the coupler. One and other vibrating arms generated by Coriolis force based on torsional vibrations of opposite phases displaced around the Y 'axis of the one and other vibrating arms propagated from the tuning fork crystal resonator and acceleration in the Z' axis direction A detection-side tuning fork for acceleration detection for detecting, via an electrode, an AC voltage generated by bending vibrations having opposite phases in the X-axis direction.

[0010] The acceleration sensor according to the second aspect is the first aspect.
In the acceleration sensor described above, the resonance frequencies of the torsional vibrations of opposite phases displaced around the Y 'axis of one and the other vibrating arms of the drive-side tuning fork and the resonance frequencies of the one and the other vibrating arms of the detection-side tuning fork in the X-axis direction are different from each other. The resonance frequencies of the opposite-phase bending vibrations are substantially equal to each other, and the resonance frequencies of the opposite-phase bending vibrations displaced in the X-axis direction of one and the other vibrating arms of the drive-side tuning fork and one and the other of the detection-side tuning fork. The vibrating arm of the drive-side tuning fork and the vibrating arm of the detection-side tuning fork are set to have different shapes and sizes so that the resonance frequencies of the torsional vibrations of opposite phases displaced around the Y 'axis of the vibrating arm of the present invention are different from each other. It is characterized by.

The acceleration sensor according to the third aspect is the first aspect.
In the acceleration sensor described above, the resonance frequency of the opposite-phase bending vibration displaced in the X-axis direction of the one and the other vibrating arms of the drive-side tuning fork and the opposite-phase torsional vibration displaced around the Y 'axis and the detection-side tuning fork The one and the other vibrating arms are driven so that the resonance frequency of the bending vibration of the opposite phase in the X-axis direction and the resonance frequency of the torsional vibration of the opposite phase displaced around the Y ′ axis are different from each other. The vibrating arm of the side tuning fork and the vibrating arm of the detection side tuning fork are set to have different shapes and sizes.

According to a fourth aspect of the present invention, there is provided the acceleration sensor according to the first aspect.
In the acceleration sensor described above, the electrodes arranged on the peripheral surface of one and the other vibrating arms of the drive-side tuning fork are respectively divided into three in the circumferential direction on the front and back surfaces of the one and the other vibrating arms when viewed in the Z′-axis direction. Each of the one and the other vibrating arms is divided into three, and the outer and inner surfaces of the vibrating arm are divided into three, the outer electrode is the outer electrode, the middle electrode is the middle electrode, and the inner electrode is the inner electrode. In this case, the inner surface electrode, the outer surface electrode, and the middle back electrode of one vibrating arm, the inner back electrode, the outer back electrode, and the middle surface electrode of the other vibrating arm are commonly connected, and the other vibrating arm has The inner electrode on the front surface, the outer electrode on the front surface, the middle electrode on the back surface, the inner electrode on the back surface of one vibrating arm, the outer back electrode, and the middle electrode on the front surface are commonly connected.

According to a fifth aspect of the present invention, there is provided the acceleration sensor according to the first aspect.
In the acceleration sensor described above, the electrodes disposed on the circumferential surface of one and the other vibrating arms of the detection-side tuning fork are respectively provided on the four circumferential surfaces on the front and back sides and on both sides of the one and the other vibrating arms when viewed in the Z′-axis direction. The four vibrating arms are provided in a state of being divided into four in the circumferential direction. The front and back electrodes of the one vibrating arm and the both side electrodes of the other vibrating arm are connected in common. It is characterized in that the front and rear electrodes and both side electrodes of the one vibrating arm are commonly connected.

According to the sixth aspect of the present invention, there is provided an acceleration sensor according to the first aspect.
In the acceleration sensor described above, the connector has a columnar shape with both end faces having an area, and both end faces are bonded to a surface partially including a vibrating node generated in a support portion of the drive-side tuning fork and the detection-side tuning fork. It is characterized by having. According to a seventh aspect of the present invention, in the acceleration sensor according to the first aspect, each of the driving-side tuning fork and the detection-side tuning fork has a through-hole having an area partially including a vibration node generated in the support portion. The connector has a columnar shape, and is bonded to the supporting portions of the drive-side tuning fork and the detection-side tuning fork in a state where both ends are inserted through the through holes.

According to an eighth aspect of the present invention, the one and other vibrations of the substantially U-shaped tuning-fork type quartz blank having a shape in which one and the other symmetric vibrating arms of a rectangular cross section are connected in parallel and integrally by a support portion are provided. First and second tuning-fork type quartz resonators each having electrodes disposed on the peripheral surface of the arm,
The first tuning-fork type quartz vibrator is fixed to the supporting portion via a connector in a state where the vibrating arms are parallel to each other and faced to each other by applying an AC voltage via an electrode. A drive-side tuning fork that generates torsional vibrations of opposite phases displaced around the longitudinal direction of the first tuning-fork type quartz vibrator from the first tuning-fork type quartz vibrator via the coupler. One and the other generated by Coriolis force based on torsional vibrations of opposite phases displaced around the longitudinal direction of the propagated one and other vibrating arms and acceleration in a direction orthogonal to the direction in which the one and other vibrating arms are arranged. A detection-side tuning fork for detecting an acceleration that detects, via an electrode, an AC voltage generated by bending vibrations of opposite phases in the arrangement direction of the other vibrating arms.

[0016]

According to the first aspect of the present invention, an AC voltage is applied to the first tuning-fork type quartz vibrator serving as the driving-side tuning fork via an electrode, so that one of the vibrating arms of the other tuning arm is applied to the driving-side tuning fork. Torsional vibrations of opposite phases displaced about the Y 'axis are generated. The torsional vibrations of opposite phases displaced around the Y 'axis are caused when an acceleration in the Z' axis direction is applied to one and the other vibrating arms (of course, the same tuning is given to the second tuning-fork type quartz vibrator). , And Z'-axis direction, Coriolis force generates bending vibrations of one and the other vibrating arms of the first tuning-fork type quartz vibrator having phases opposite to each other in the X-axis direction. An AC voltage generated by bending vibrations of one and the other vibrating arms of the first tuning-fork type quartz vibrator having mutually opposite phases in the X-axis direction is detected via the electrodes. This AC voltage is Z '
Since the value is proportional to the acceleration in the axial direction, the acceleration in the Z'-axis direction can be detected from the AC voltage.

According to the second aspect of the present invention, the resonance frequency of the bending vibration in the X-axis direction of one and the other vibrating arms of the drive-side tuning fork and the mutual resonance frequency of the one and the other vibrating arms of the detection-side tuning fork in the X-axis direction. The resonance frequencies of the opposite-phase bending vibrations are substantially equal to each other, and the resonance frequencies of the opposite-phase bending vibrations displaced in the X-axis direction of one and the other vibrating arms of the drive-side tuning fork and one and the other vibration of the detection-side tuning fork. When the driving-side tuning fork is driven to resonate due to the fact that the resonance frequencies of torsional vibrations of opposite phases displaced about the Y 'axis of the arm are different from each other, the detection-side tuning fork is rotated around the Y' axis of one and the other vibrating arms. A phase-dependent bending vibration in the X-axis direction generated on one and the other vibrating arms of the tuning fork on the detection side is efficiently extracted by a Coriolis force based on the torsional vibration of the opposite phase and the Coriolis force based on the acceleration in the Z'-axis direction. Both the influence of opposite phases of torsional vibration is displaced about Y 'axis is reduced. As a result,
It is possible to effectively detect the AC voltage generated by the opposite-phase bending vibrations in the X-axis direction while suppressing the influence of the AC voltage generated by the opposite-phase torsional vibration displaced around the Y 'axis, and to accurately detect the Z'-axis. It is possible to detect the acceleration in the direction.

According to the third aspect of the present invention, the resonance frequencies of the oppositely displaced bending vibrations displaced in the X-axis direction of the one and the other vibrating arms of the drive-side tuning fork and the opposite phases displaced about the Y 'axis. The resonance frequency of the torsional vibration of the detecting side tuning fork and the resonance frequency of the bending vibration of the opposite phase in the X axis direction of the one and the other vibrating arms of the detecting side tuning fork and the resonance frequency of the torsional vibration of the opposite phase displaced around the Y 'axis are separated from each other. In the case where the drive-side tuning fork is driven in resonance, the detection-side tuning fork is driven by Coriolis based on torsional vibrations in opposite phases displaced around the Y 'axis of one and the other vibrating arms and acceleration in the Z' axis direction. The opposite phase torsional vibrations displaced around the Y 'axis do not affect the X-axis bending vibrations in the X-axis direction generated on one and the other vibrating arms of the detection-side tuning fork due to the force of. As a result, it is possible to effectively detect the AC voltage generated by the opposite-phase bending vibrations in the X-axis direction while suppressing the influence of the AC voltage generated by the opposite-phase torsional vibration displaced around the Y 'axis, and to accurately detect the AC voltage. The acceleration in the Z'-axis direction can be detected.

According to the fourth aspect of the present invention, an alternating voltage is applied between the two sets of commonly connected electrodes of the driving-side tuning fork, and the torsions having opposite phases are displaced around the Y 'axis of one and the other vibrating arms. Causes vibration. At this time, the frequency of the AC voltage is close to the resonance frequencies of the torsional vibrations of opposite phases displaced around the Y 'axis of the one and the other vibrating arms, and the drive-side tuning fork is driven in resonance.

According to the fifth aspect of the present invention, between the two sets of commonly connected electrodes of the detection-side tuning fork, an alternating current generated by one and the other vibrating arms due to bending vibrations having opposite phases in the X-axis direction. Voltage will result. According to the configuration of the sixth aspect, bending vibrations of one phase and the other vibrating arm of the driving-side tuning fork in the X-axis direction, which are in opposite phases to each other, are efficiently detected without lowering the mechanical Q value of the driving-side tuning fork. It will be transmitted to the side tuning fork.

According to the seventh aspect of the present invention, the bending vibrations of the one and the other vibrating arms of the driving-side tuning fork in the X-axis direction are opposite to each other without lowering the mechanical Q value of the driving-side tuning fork. This is transmitted to the detection-side tuning fork efficiently. According to the configuration of claim 8, since the cut-out direction of the drive-side tuning fork and the detection-side tuning fork is arbitrary, there is a difference in characteristics due to a difference in the cut-out direction.
Works in the same way as

Here, the reason why the two substantially U-shaped tuning-fork type quartz vibrators are connected and integrated via a connector will be described. If an acceleration is applied to the Z 'axis of the tuning-fork crystal unit, a Coriolis force is generated in each vibrating arm in a direction symmetric to the X-axis due to the displacement speed v due to the acceleration. I do. At this time, the generated vibration in the X-axis symmetric direction vibrates in the torsional vibration around the Y 'axis and the X-axis direction component orthogonal to the Z-axis acceleration direction. In other words, the principle of acceleration detection is that when one and the other vibrating arms generate torsional vibrations of opposite phases displaced about the Y 'axis, if a displacement speed v due to acceleration is applied to the vibrating arms, Coriolis The force is newly generated as bending vibration in the X-axis direction orthogonal to the Z-axis direction. The acceleration can be detected by detecting the component of the bending vibration.

However, in the case of a single tuning-fork type quartz resonator, the resonance frequency of the torsional vibrations of opposite phases displaced around the Y 'axis of the resonance drive and the newly generated X-axis direction Since the non-resonant frequencies of the bending vibrations having opposite phases are the same frequency, it is generally difficult to separate them. This is due to provision of the separation electrode and the like.
Even if the mode can be separated and detected well,
Since the detection level is extremely low with respect to the strong level of the resonance drive, the detection level is masked by the influence of induction or the like, or is affected by the detection level, so that accurate detection cannot be performed. Thus, some solution for separating drive and detection by frequency differences was desired.

Therefore, the present invention solves this difficulty by joining two substantially U-shaped tuning-fork type quartz vibrators via a connector to separate them into a drive side and a detection side.
In the present invention, the crystal resonator itself has a pair of vibrating arms arranged in plane symmetry, and one of two substantially U-shaped tuning fork-shaped crystal resonators having a tuning fork shape is a driving side tuning fork, and the other is a driving side tuning fork. It is a detection-side tuning fork and integrated with a connector.

By using quartz as a material of these tuning forks, high sensitivity of acceleration detection, small thermal expansion coefficient, and torsional vibrations of opposite phases displaced around the Y 'axis by electrode arrangement are provided. Accordingly, acceleration can be detected, and the frequency dependence of the crystal with respect to a temperature change becomes smaller. As a result, the temperature drift of the acceleration sensor is reduced, and the temperature is reduced. In addition, the driving signal component on the driving side is less mixed into the detection side as an unnecessary signal component, the resonance frequency fluctuation at the time of driving is small, and the phase shift change at the time of synchronous detection is small. As a result, an acceleration sensor having excellent temperature characteristics in a wide temperature range can be obtained.

Here, the operation of the present invention will be described a little more. This means that a new vibration mode (in this case, Z mode) due to Coriolis force is generated (absolutely not resonance) in a tuning fork that vibrates in a specific driving mode (in this case, X mode) that vibrates greatly. Therefore, the generated new vibration mode (in this case, Z mode, but the frequency is synchronized with the drive mode, so it is the same as the drive mode) is selectively (a kind of mechanical filtering) by mode resonance. It is to detect.

In other words, if the drive side vibration mode is mixed with the detection side tuning fork, erroneous detection may occur (because the level is isolated to 100 dB), so that the detection vibration mode can be selected from the drive vibration mode. As described above, the electrode structure of the detection-side tuning fork is different from that of the driving-side tuning fork, and the shape and size of the vibrating arm are different so as to provide resonance selection characteristics with respect to the resonance frequency. In the detection side tuning fork,
The drive mode is suppressed as much as possible, and only the detection mode is detected as efficiently as possible.

In the present invention, since a plurality of vibration modes are handled, measures against them are important points. That is, the bending vibrations having opposite phases displaced in the X-axis direction are transmitted from the support portion of the first tuning-fork type quartz vibrator of the driving-side tuning fork via the coupler to the second tuning-fork type quartz vibrating which is the detection-side tuning fork. Partially propagated to the support of the child, but the X of the second tuning fork
Since it is set so that the resonance frequency and the bending vibration of the opposite phases displaced in the axial direction do not coincide with each other and do not resonate, most are confined in the drive-side tuning fork. At this time, if the rotation angular velocity around the Y 'axis is given to the first tuning fork crystal resonator (the same rotation angular velocity is given to the second tuning fork crystal resonator as a matter of course), the first tuning fork crystal resonator is given the second rotation by the Coriolis force. Bending vibrations having opposite phases in the Z'-axis direction of one and the other vibrating arms of the tuning fork-shaped quartz resonator 1 are newly generated. The flexural vibrations having opposite phases in the Z'-axis direction propagate to the second tuning-fork type quartz vibrator through the coupler, and are set to be substantially equal to the resonance frequency of the flexural vibrations having opposite phases in the Z'-axis direction. If it is, it can be detected efficiently.

The detection using the resonance phenomenon has high sensitivity and high efficiency, so it is suitable for miniaturization and high accuracy. However, it has a disadvantage that it is easily affected by other signal interference. In addition, when a large number of different vibrations such as bending vibrations having opposite phases in the X-axis direction or bending vibrations having opposite phases in the Z'-axis direction are to be used, it is necessary to eliminate and suppress interference due to unnecessary vibration. Special attention must be paid to A relatively easy countermeasure is to set the resonance frequencies apart from each other or to avoid proximity, at the expense of some sensitivity.

Fortunately, since these various vibrations are orthogonal to each other and the boundary conditions are independent of each other, there is an advantage that they are easy to control without mutual interference. For example, the bending vibration displacing in the Z′-axis direction and the bending vibration displacing in the X-axis direction use the length of the vibrating arm as a common boundary condition for frequency determination, while the thickness and width are other boundary conditions. Therefore, by making the thickness and the width different from each other in addition to the difference between the piezoelectric constants, the resonance frequencies can be very easily isolated and set differently.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an acceleration sensor according to a first embodiment of the present invention. FIG. 1A is a perspective view in an assembled state, and FIG. 1B is a perspective view in an exploded state. In FIG. 1, reference numeral 21 denotes a first tuning fork-shaped quartz vibrator made of a substantially U-shaped tuning fork-shaped quartz blank having a shape in which one and the other symmetrical vibrating arms 24 and 25 having a rectangular cross section are connected in parallel and integrally by a support portion 23, respectively. The drive electrode 22 is cut out by a working (hereinafter referred to as a drive-side tuning fork) by electric processing or mechanical processing, and driving electrodes 22 are arranged on the peripheral surfaces of the one and the other vibrating arms 24 and 25. Reference numeral 26 denotes a second tuning-fork type crystal resonator (hereinafter, referred to as a second tuning-fork type crystal resonator) comprising a substantially U-shaped tuning-fork type crystal blank having a shape in which one and the other symmetrical vibrating arms 29 and 30 having the same rectangular cross section are connected in parallel and integrally by the support portion 28. , A detection-side tuning fork), and a detection electrode 27 is disposed on the peripheral surface of one and the other vibrating arms 29, 30.

Numeral 31 is a connector having a rectangular cross section made of quartz.
A joint portion 3 partially including a drive-side vibrating node whose both end surfaces are located substantially at the center surfaces of the drive-side support portions 23 and the detection-side support portions 28 of the drive-side tuning fork 21 and the detection-side tuning fork 26, respectively.
2 and a joint 33 partially including the detection-side vibrating node are bonded by an adhesive to form an acceleration sensor. in this case,
The drive-side tuning fork 21 and the detection-side tuning fork 26 are in parallel with each other and face each other. The connector 31 has a function of transmitting the vibration of the drive-side tuning fork 21 to the detection-side tuning fork 26, and the connector 31 forms a tuning fork together with the drive-side tuning fork 21 and the detection-side tuning fork 26. It is considered that

A substantially U-shaped tuning fork crystal blank used for the driving tuning fork 21 and the detection tuning fork 26, which are essential parts, will be described below. FIG. 2 is a perspective view of a substantially U-shaped tuning fork crystal blank used for the driving tuning fork 21 and the detection tuning fork 26. In FIG. 2, reference numeral 34 denotes a substantially U-shaped tuning fork crystal blank having a substantially concave shape used for the driving tuning fork 21 and the detection tuning fork 26. This crystal blank 34 has crystal axes X, Y,
A new crystal axis X, Y ', Z' rotated around the X axis by an angle θ (= 1 to 3 °) with respect to Z is cut out in the X, Y 'plane with the Y' axis direction as a longitudinal direction. This is a structure in which two parallel vibrating arms 35A and 35B are connected by a support 35C.

Here, an example of the dimensions of the crystal blank constituting the substantially U-shaped tuning fork crystal resonator will be described. For example, as a first embodiment, the vibrating arms of the drive-side tuning fork and the detection-side tuning fork are made of quartz in a U-shape having a length (L) of 10 mm, a thickness (t) of 2.5 mm, and a width (W) of 3.5 mm. It is molded in the cut direction shown in FIG. The dimensions of the drive-side tuning fork and the detection-side tuning fork are not limited to the above example, and the dimensions of both tuning forks need not be the same, and are opposite torsional vibrations displaced around the Y 'axis and opposite to each other in the X-axis direction. It is set appropriately according to the resonance frequency of the bending vibration of the phase.

The substantially U-shaped tuning fork crystal blank 34 is shown in FIG.
When used for the drive-side tuning fork 21 and the detection-side tuning fork 26 of the acceleration sensor shown in (1), the resonance frequencies of torsional vibrations of opposite phases displaced around the Y 'axis of the drive-side tuning fork 21 and the X-axis direction of the detection-side tuning fork 26 The resonance frequencies of the opposite-phase bending vibrations are equal to each other, and the resonance frequencies of the opposite-phase bending vibrations in the X-axis direction of the drive-side tuning fork 21 and the opposite-phase displacement of the detection-side tuning fork 26 around the Y 'axis are different. It is cut out and used in such a shape and size that the resonance frequency of the torsional vibration is different.

The drive-side tuning fork 21 is connected to a drive electrode 22
To generate torsional vibrations of opposite phases, which are displaced around the Y 'axis of the one and other vibrating arms 24 and 25. In this case, the resonance drive is performed with the frequency of the AC voltage substantially equal to the resonance frequency of the torsional vibrations of opposite phases displaced around the Y 'axis.

The detection-side tuning fork 26 is a Coriolis force based on torsional vibrations of opposite phases displaced around the Y 'axis propagated from the driving-side tuning fork 21 via the connector 31 and acceleration in the Z'-axis direction. The AC voltage generated by the bending vibrations of the one and the other vibrating arms 29 and 30 in the opposite phases in the X-axis direction generated by the vibration arms 29 and 30 is detected via the electrodes. Hereinafter, a specific configuration of the driving electrode 22 as a main part will be described. FIG. 3 is a connection diagram of a driving electrode 22 formed on the peripheral surface of one and the other vibrating arms of the driving-side tuning fork 21 as a main part. In FIG. 3, 36a, 36b, and 36c are outer portions formed on the surface of one vibrating arm 24 when viewed from the Z 'axis direction.
The middle and inside drive electrodes 36d, 36e and 36f are outside, middle and inside drive electrodes formed on the back surface of one vibrating arm 24 as viewed from the Z 'axis direction. 37a, 37
b, 37c are inner, middle, and outer drive electrodes 37 formed on the surface of the other vibrating arm 25 viewed from the Z 'axis direction.
Reference numerals d, 37e, and 37f denote inner, middle, and outer drive electrodes formed on the back surface of the other vibrating arm 25 when viewed from the Z'-axis direction. As shown in FIG. Each of the vibrating arms is provided on the front and back surfaces of the other vibrating arm so as to be divided into three in the circumferential direction.

The driving electrodes 36a, 36c, 36e on the front and back surfaces of one vibrating arm 24 and the driving electrodes 37b, 37d, 37f on both side surfaces of the other vibrating arm 25 are commonly connected, and the other vibrating arm 24 is connected. 25 drive electrodes 37a, 3 on the front and back
7c, 37e and the driving electrodes 36b, 36d, 37f on both sides of one vibrating arm 24 are commonly connected. Driving electrodes 36a, 36c, 36e, 37b, 37d, 37f
And the driving electrodes 36b, 36d, 3
6f, 37a, 37c and 37e are connected to the vibrating arm 2
This is performed by extending the electrode pattern on the peripheral surfaces of the layers 4 and 25.

Reference numeral 38 denotes driving electrodes 36a, 3 which are connected in common.
6c, 36e, 37b, 37d, 37f are connected to a common line, and 39 is a commonly connected drive electrode 36b, 36.
d, 36f, 37a, 37c, 37e. The driving electrode 22 configured as described above
When the resonance drive is performed by applying a drive signal (AC voltage) between the common lines 38 and 39, the one and the other vibrating arms 24 and 25 are displaced around the Y 'axis in opposite phases. A torsional vibration occurs, and one vibrating arm 24 and the other vibrating arm 25 of the driving tuning fork 21 are twisted in directions opposite to each other.

Hereinafter, a specific configuration of the detection electrode 27 which is a main part will be described. FIG. 4 is a connection diagram of the detection electrodes 27 formed on the four peripheral surfaces on the front and back sides and both sides of one and the other vibrating arms of the detection-side tuning fork 26 which is a main part. In FIG. 4, reference numerals 40a and 40c denote detection electrodes formed on the front and back surfaces of one vibrating arm 29 when viewed from the Z'-axis direction, and reference numerals 40b and 40d denote detection electrodes viewed from the Z'-axis direction of the one vibrating arm 29. These are detection electrodes formed on both side surfaces. 41a and 41c are detection electrodes formed on the front and back surfaces of the other vibrating arm 30 when viewed from the Z 'axis direction, and 41b and 41d are formed on both side surfaces when viewed from the Z' axis direction of the other vibrating arm 30 respectively. Formed sensing electrode,
As shown in FIG. 1, when viewed in the Z'-axis direction, the one and the other vibrating arms are provided on the front and back surfaces and on the four circumferential surfaces on both sides, respectively, in a state of being divided into four by four ridges in the circumferential direction.

The detection electrodes 40a and 40c on the front and back surfaces of one vibrating arm 29 and the detection electrodes 41b and 41d on both side surfaces of the other vibrating arm 30 are commonly connected, and the front and back surfaces of the other vibrating arm 30 are connected. And the detection electrodes 40b and 40d on both sides of one vibrating arm 29 are commonly connected. Detection electrodes 40a, 40c, 41b, 41
d, and the detection electrodes 40b, 40d, 4
The common connection of 1a and 41c is performed by extending the electrode pattern on the peripheral surfaces of the vibrating arms 29 and 30.

Reference numeral 42 denotes commonly connected detection electrodes 40a, 4
Common lines connected to Oc, 41b, 41d, 43 are commonly connected detection electrodes 40b, 40d, 41a, 41c.
It is a common line connected to. Hereinafter, the vibration nodes shown as the driving-side vibration nodes 32 and the detection-side vibration nodes 33 in FIG. 1 will be described in detail. FIG. 5 is a side view of the substantially U-shaped tuning fork crystal blank 34, showing a configuration for detecting vibration nodes. FIG. 6A is a perspective view of a substantially U-shaped tuning fork crystal blank 34 showing the position of a vibrating node, FIG. 6B is a front view thereof, and FIG. 6C is a side view thereof.

In FIG. 5, the substantially U-shaped tuning fork crystal blank 34 is held by a symmetrical pinpoint support 43 so as to sandwich the supporting portion 35C of the substantially U-shaped tuning fork crystal blank 34. An electric signal is given to the blank 34 to give a direction in which the vibrating arms 35A and 35B open and close, that is, an X-mode bending vibration, as shown in the arrow direction (X-axis direction) in FIGS. Then, the mechanical sharpness of bending vibration (resonance) (hereinafter referred to as “mechanical Q value”) is measured, and a point at which the mechanical Q value decreases little is measured. FIG.
The hatched portions below the curves AMB and BNC shown in (a), (b) and (c) indicate portions where the decrease of the mechanical Q value remains within several%.

The curves AMB and BNC are defined as vibrating nodes for convenience. That is, a substantially U-shaped tuning fork crystal blank 3
4 represents a line near the boundary between the vibrating part and the non-vibrating part. That is, when two substantially U-shaped tuning fork-shaped quartz blanks are joined by a connector having a certain area so as to include the same, bending vibration of one substantially U-shaped tuning fork-shaped quartz blank is performed well, and one substantially U-shaped tuning fork-shaped quartz blank is performed. A vibrating node is a portion where the bending vibration of the U-shaped tuning fork crystal blank is easily transmitted to the other approximately U-shaped tuning fork crystal blank.

6 (b) and 6 (c) show the vibration state in the X mode by dotted lines, and the side surface of the substantially U-shaped tuning fork crystal blank vibrates to the lower side as compared to the front and back surfaces. It is shown that. Depending on the dimensions of the vibrating arm and the support, if the support is sufficiently large, point M is approximately at the midpoint. The N point is at 80% to 90% of the support. If the coupling is performed in the oblique line on the symmetry axis of the tuning fork passing through the point M, the resonance Q value of the substantially U-shaped tuning fork crystal blank serving as the driving side tuning fork is small, but the substantially U-shaped tuning fork crystal serving as the detection side tuning fork is reduced. The transmission of vibration energy to the blank is very poor.

Therefore, if coupling is performed with a connector having a certain area including the vibrating node formed by the curve AMB, effective vibration can be transmitted and received. For example, they may be connected by a columnar connector having a rectangular PQRS centered at the point M (see FIG. 6B) as an adhesive area. The size of the area of the rectangular PQRS is a matter of design in consideration of the size of the support.

FIGS. 7 and 8 show one experimental example showing the degree of reduction of the mechanical Q value with respect to the pinpoint support position (x). Fig. 7 shows the dimensions and cut axis of the sample of the substantially U-shaped tuning fork crystal blank used in the experiment.
(A) and (b) show. In FIGS. 7A and 7B,
Dimensions z ₁ is 95 mm, z ₂ is 25 mm, z ₃ is 70 mm, z ₄
Is 5mm, z ₅ is 15mm. With respect to the substantially U-shaped tuning fork-shaped quartz blanks shown in FIGS. 7A and 7B, X-mode vibration is caused, and the pinpoint support positions are set on the h line, the g line,
The degree of reduction of the mechanical Q value was measured by moving on the h 'line and the i line. FIG. 8 shows the experimental results.
The vertical axis of the experimental results shown in FIG. 8 cannot support the bottom (x = 0) of the substantially U-shaped tuning fork-shaped quartz blank, so that the vertical axis was standardized using data of x = 2 mm. In FIG. 8, the solid line indicates the characteristic on the g line,
The broken lines indicate the characteristics on the h line and the h 'line, and the alternate long and short dash line indicates the characteristics on the i line. From this figure, it can be seen that the side of the vibrating arm and the supporting portion of the substantially U-shaped tuning fork crystal blank is affected by the pinpoint support far below the front and back surfaces.

On h and h ', it can be seen that the mechanical Q value is not affected even if the supporting point is considerably close to the vibrating arm. The operation principle of the acceleration sensor configured as described above will be described below. FIG. 9A is a diagram illustrating the principle of the acceleration sensor of the present invention. In FIG. 9A, an acceleration is applied in the ± Z-axis direction that is plane-symmetric with respect to the XY plane,
At this time, the speed at which the prism having a mass of 2 m is displaced is defined as v. Assuming that the displacement of the prism body is torsional vibration of the angular velocity vector ω around the Y axis, ± Z which is plane symmetric with respect to the XY plane
When acceleration is applied in the axial direction, these prisms have 2 mΩ
A Coriolis force F expressed by a vector cross product of × v is generated.

Since the Coriolis force F is perpendicular to the plane defined by the vectors ω and v in the right coordinate direction, the applied acceleration can be directly detected by detecting the generated Coriolis force vector F. You can. Assuming that the displacement of the prism is d = A sin Ωt, the velocity | v | is | v | = dd / dt = AΩ cos Ωt, and the force | F | | F | = 2 mAΩ | ω |.

Here, the output signal of the acceleration sensor, the force | F
Is output in proportion to |, the acceleration can be known from the output signal of the acceleration sensor. Here, FIG. 9B is a diagram showing the operation principle of the crystal blank 34 which is a main part of the present invention, and corresponds to the principle diagram of FIG. 9A. FIG.
In (b), assuming that the vibrating arms 35A and 35B perform torsional vibrations (angular velocities) of opposite phases in which the vibrating arms 35A and 35B are displaced around the Y 'axis, when acceleration is applied in the Z axis direction of the crystal blank 34, X is attached to each vibrating arm 35A, 35B.
A Coriolis force F is generated in the axial direction.

The operation of the acceleration sensor according to the first embodiment of the present invention will be described below. FIG. 10 is a plan view of the acceleration sensor for explaining the operation when viewed from the Y′-axis direction. The following operation is mainly performed. As described above, the AC voltage is applied to the driving electrodes of the vibrating arms 24 and 25 by using vibration driving means (not shown) so that the driving-side tuning fork 21 maintains torsional vibrations of opposite phases displaced around the Y 'axis. When the vibrating arms 24 and 25 are torsionally vibrated by adding
Another mode of vibration is generated by the Coriolis force and propagates to the detection-side tuning fork 26. Due to the vibration component propagated through the connector 31 to the detection-side tuning fork 26, the detection-side tuning fork 26 is displaced around the Y 'axis torsionally vibrates in opposite phases. On the other hand, the electric signal of the vibration component of the bending vibration having the opposite phase in the X-axis direction of the detection-side tuning fork 26, that is, the Coriolis force is transmitted from the detection electrodes provided on the surfaces of the vibrating arms 29 and 30 of the detection-side tuning fork 26. By extracting the AC signal by the signal detecting means (not shown) as described above, an acceleration signal corresponding to the rotational angular velocity of the driving tuning fork 21 and the detection tuning fork 26 can be obtained. The following operation is also performed. The vibrating arms 24 and 2 are provided to the driving-side tuning fork 21 using vibration driving means (not shown) so as to maintain torsional vibrations of opposite phases displaced around the Y 'axis.
When the AC voltage is applied to the drive electrode 5 as described above and the vibrating arms 24 and 25 are torsionally vibrated, the detection-side tuning fork 26 moves around the Y 'axis due to the vibration component propagated through the connector 31 to the detection-side tuning fork 26. Displaced torsional vibrations of opposite phases occur. On the other hand, the electric signals of the vibration components of the flexural vibrations of the opposite phases in the X-axis direction perpendicular to the vibration direction of the detection-side tuning fork 26, that is, the Coriolis force, are used as the vibration arms 29 and 30 of the detection-side tuning fork 26. As described above, an AC signal is extracted from the detection electrode provided on the surface by the signal detection means (not shown), whereby an acceleration signal corresponding to the rotational angular velocity of the drive-side tuning fork 21 and the detection-side tuning fork 26 is obtained.

According to the acceleration sensor of this embodiment, the vibrating arms 24 and 25, which are not the bonding type as in the conventional example, are used as the drive-side tuning fork 21 and the detection-side tuning fork 26;
Since a substantially U-shaped tuning-fork type crystal blank in which the 29, 30 and the support portions 25; 28 are integrated respectively is used, the acceleration can be detected with high temperature characteristics over a wide temperature range, with little variation, and with high accuracy. Can be.

The resonance frequencies of the torsional vibrations of the opposite phases displaced around the Y 'axis of one and the other vibrating arms 24 and 25 of the drive-side tuning fork 21 are opposite to those of the detection-side tuning fork 26 in the X-axis direction. The resonance frequencies of the bending vibrations which are substantially equal to the resonance frequency of the bending vibration and which are displaced in the X-axis direction of the one and the other vibration arms of the drive-side tuning fork 21 and the one and the other vibration arms of the detection-side tuning fork 26 are opposite to each other. Since the resonance frequencies of the torsional vibrations of the opposite phases displaced around the Y 'axis of the 29 and 30 are different from each other, when the drive-side tuning fork 21 is driven in resonance, the opposite phases displaced about the Y' axis. The torsional vibration and the Coriolis force based on the acceleration in the Z'-axis direction efficiently extract the opposite-phase bending vibrations in the X-axis direction generated in the one and the other vibrating arms 29, 30 and around the Y'-axis. Coordinating possible to reduce the influence of the reverse phase of the torsional vibration each other. As a result, it is possible to effectively detect the AC voltage caused by the opposite-phase bending vibrations in the X-axis direction while suppressing the effect of the AC voltage caused by the opposite-phase torsional vibration displaced around the Y ′ axis, and with high accuracy. Z '
Axial acceleration can be detected.

Further, both end surfaces of the connector 31 are connected to the drive-side tuning fork 2.
1 and the supporting portions 23 and 28 of the detection-side tuning fork 26 are adhered to the surface partially including the vibrating nodes, so that the torsional vibrations of opposite phases displaced around the Y 'axis of the driving-side tuning fork 21 are prevented. It is possible to transmit to the detection-side tuning fork 26 with maximum mechanical transmission efficiency without lowering the mechanical Q value of the driving-side tuning fork 21,
6 can be easily integrated with the connector 31 and the manufacture is easy.

Here, the characteristics and effects of the above embodiment will be described in comparison with the conventional example. According to the above-described embodiment of the present invention, the drive-side tuning fork 21 and the detection-side tuning fork 26, each of which is formed of a substantially U-shaped tuning fork-shaped crystal unit, are integrated by the connector 31 so as to face each other in parallel. High resonance sharpness (mechanical Q value), high angular velocity detection sensitivity, low thermal expansion coefficient, stable drive frequency, and as a result, the phase shift change of synchronous rectification in the above-described sensor signal processing And a part of the drive signal component on the drive side is not mixed into the detection section as an unnecessary signal component, and as a result, the drift stability can be obtained as excellent as 1/10 of the conventional one. Was.

FIG. 11 is a perspective view of an acceleration sensor according to a second embodiment of the present invention. FIG. 1A is a perspective view in an assembled state, and FIG. 1B is a perspective view in an exploded state. The acceleration sensor of this embodiment uses a columnar connector 31A instead of the prismatic connector of FIG. 1, and the other configuration is the same as that of FIG. The effect of this embodiment is the same as that of the first embodiment.

FIG. 12 is a perspective view of an acceleration sensor according to a third embodiment of the present invention. FIG. 1A is a perspective view in an assembled state, and FIG. 1B is a perspective view in an exploded state. In the acceleration sensor of this embodiment, circular through holes 23a and 28a having a certain area including a vibrating node are provided in the support portions 23 and 28 of the drive side tuning fork 21 and the detection side tuning fork 26 by, for example, etching, and the connector 31A is provided with the through hole. It is bonded in a state where it is inserted through 23a and 28a. Other configurations are the same as those of the embodiment of FIG.

In this embodiment, both ends of the connector 31A are supported by the support portions 23, 28 of the drive-side tuning fork 21 and the detection-side tuning fork 26.
Holes 23a, 28 partially including vibrating nodes generated in
a, the drive-side tuning fork 21
Can be transmitted to the detection-side tuning fork 26 with the maximum mechanical transmission efficiency without lowering the mechanical Q value of the driving-side tuning fork 21 and displacing in the X-axis direction. Connecting the tuning fork 21 and the coupling side tuning fork 26 to the connector 3
At 1A, it is strongly integrated and has excellent vibration resistance. Other effects are similar to those of the first embodiment.

FIG. 13 is a perspective view of an acceleration sensor according to a fourth embodiment of the present invention. FIG. 1A is a perspective view in an assembled state, and FIG. 1B is a perspective view in an exploded state. In the acceleration sensor of this embodiment, rectangular through holes 23b and 28b having a certain area including a vibrating node are provided in the support portions 23 and 28 of the drive-side tuning fork 21 and the detection-side tuning fork 26 by, for example, etching. It is bonded in a state where it is inserted into the holes 23b and 28b. Other configurations are the same as those of the embodiment of FIG.

In this embodiment, both ends of the connector 31 are connected to the through-holes 23b and 28b partially including vibrating nodes formed in the supporting portions 23 and 28 of the driving-side tuning fork 21 and the detecting-side tuning fork 26.
, The bending vibrations of the opposite phases displaced in the X-axis direction of the driving-side tuning fork 21 without reducing the mechanical Q value of the driving-side tuning fork 21 and the maximum mechanical transmission. The driving fork 21 and the coupling-side tuning fork 26 can be transmitted to the detection-side tuning fork 26 with high efficiency.
It is strongly integrated and has excellent vibration resistance. Other effects are similar to those of the first embodiment.

In each of the above embodiments, the resonance frequencies of the torsional vibrations of opposite phases displaced around the Y 'axis of the one and the other vibrating arms of the drive-side tuning fork and the one and the other vibrating arms of the detection-side tuning fork. The resonance frequencies of the opposite-phase bending vibrations in the X-axis direction are substantially equal to each other, and the resonance frequencies of the opposite-phase bending vibrations displaced in the X-axis direction of one and the other vibrating arms of the drive-side tuning fork and the resonance frequency of the detection-side tuning fork. The vibrating arm of the driving-side tuning fork and the vibrating arm of the detecting-side tuning fork are set to have different shapes and sizes so that the resonance frequencies of the torsional vibrations of the opposite phases displaced about the Y 'axis of the one and the other vibrating arms are different. However, instead of this, as a fifth embodiment, the resonance frequency of the torsional vibrations of opposite phases, which are displaced around the Y 'axis of one and the other vibrating arms of the drive-side tuning fork, are displaced in the X-axis direction. Resonance of flexural vibrations of opposite phases The resonance frequency of the torsional vibration of the opposite phase and the resonance frequency of the bending vibration of the opposite phase in the X-axis direction, which are displaced around the Y 'axis of the one and the other vibrating arms of the detection-side tuning fork, are separated from each other and different from each other. The vibrating arm of the drive-side tuning fork and the vibrating arm of the detection-side tuning fork may be set to different shapes and sizes. In the case of setting as described above, for example, the size of the vibrating arm of the quartz blank constituting the detection-side tuning fork is set to 10 mm in length (L) × 3.5 mm in thickness (t) × 2.5 mm in width (W).
And integrated as shown in FIG.

With this configuration, the resonance frequencies of the torsional vibrations of the opposite phases displaced around the Y 'axis of the one and the other vibrating arms of the drive-side tuning fork 21 and the bending vibrations of the opposite phases displaced in the X-axis direction. And the resonance frequency of the opposite-phase torsional vibration displaced around the Y 'axis of one and the other vibrating arms of the detection-side tuning fork 26 and the resonance frequency of the opposite-phase bending vibration in the X-axis direction are different from each other. Therefore, when the drive-side tuning fork is driven by resonance, one and the other of the detection-side tuning fork 26 are driven by Coriolis force based on the torsional vibration of the opposite phase displaced around the Y 'axis and the acceleration in the Z' axis direction. With respect to the bending vibrations of the opposite phases in the X-axis direction generated in the vibrating arms 28 and 29, the torsional vibrations of the opposite phases displaced around the Y 'axis can be prevented from becoming extremely large.
As a result, it is possible to effectively detect the AC voltage generated by the opposite-phase bending vibrations in the X-axis direction while suppressing the influence of the AC voltage generated by the opposite-phase torsional vibration displaced around the Y 'axis, and to accurately detect the AC voltage. The acceleration in the Z'-axis direction can be detected. Other points are the same as those of the above-described embodiments.

It should be noted that even if the lower bottom portions of the support portions are connected to each other via a connector instead of the vibration nodes in the support portions of the drive side tuning fork and the detection side tuning fork, vibration is effective from the drive side tuning fork to the detection side tuning fork. , And such a configuration is also included as an example. In other words, any part of the support portion may be connected as long as it transmits a part of the vibration energy without decreasing the mechanical vibration sharpness of the tuning fork vibration. In addition, the bonding is performed at one place, but it is obvious that the bonding may be performed at two or more places by using two or more connectors.

The electrode structures of the drive-side tuning fork 21 and the detection-side tuning fork 26 are not limited to those shown in the above-described embodiments, but can be variously changed. In other words, it is necessary to detect bending vibration and Coriolis signal components. It is something that can be done. For example, the detection electrodes may be four electrodes formed so as to straddle the four ridges of the vibrating arm, or may be two electrodes circumferentially divided on both side surfaces of the vibrating arm.

In the above embodiment, the crystal axes X, Y, Z
New crystal axis X rotated about 2 to 3 degrees around the X axis of
A crystal blank cut out in the X, Y 'plane with the Y' axis direction of Y ', Z' as the longitudinal direction was used.
It is also possible to use a quartz blank cut out with the Y-axis direction of Y and Z taken as the longitudinal direction. Therefore, the expression of “new crystal axes X, Y ′, Z ′ rotated around the X axes of the crystal axes X, Y, Z” in the claims indicates that the rotation angle is 0 degree, that is, Axis X, Y, Z and crystal axis X,
The case where Y 'and Z' overlap each other is also included. The rotation angle of the crystal axis may be other than the angle of 2 to 3 degrees. That is, the cut-out directions of the drive-side tuning fork 21 and the detection-side tuning fork 26 are not limited to those shown in FIG.
The desired effect can be achieved even if each is cut out in the X and Y planes with the axial direction as the longitudinal direction. However, FIGS. 1 and 2
Compared with the embodiment, the effect is slightly reduced due to the difference in the cutting direction, but there is no particular problem. The desired effect can be obtained not only in the Y and Y 'axes but also in the X and X' axes and the Z and Z 'axes.

[0066]

As described above, according to the present invention,
Unnecessary signal components are reduced, low-frequency acceleration near DC can be detected in a wide temperature range, and a stable acceleration sensor with very little characteristic change even with a rapid temperature change can be obtained. Further, if the drive-side tuning fork and the detection-side tuning fork are fixed via a block connector having a certain area partially including a vibration node generated in the support portion, the mechanical Q value of the tuning-fork vibration and the drive-side tuning fork can be obtained. The efficiency of mechanical transmission from the to the detection-side tuning fork can be maximized.

Therefore, the mechanical transmission loss at the time of connecting both tuning forks can be remarkably improved, and the sensitivity of acceleration detection by Coriolis force can be improved. And since it is a structure with a simple structure, cost reduction can be achieved,
Great industrial value. And since it is a structure with a simple structure, cost reduction can be achieved and industrial value is large.

Hereinafter, the effects of each claim will be described. According to the acceleration sensor of the present invention, a substantially U-shaped tuning-fork type crystal blank in which a vibrating arm and a supporting portion, which are not a bonded type as in the conventional example, are integrally used as the driving-side tuning fork and the detection-side tuning fork, respectively. Therefore, the acceleration can be detected with high accuracy over a wide temperature range, with little variation, and with high accuracy.

According to the acceleration sensor of the present invention, the resonance frequencies of torsional vibrations of opposite phases displaced around the Y 'axis of one and the other vibrating arms of the drive-side tuning fork and one and the other of the detecting-side tuning fork. Resonance frequencies of bending vibrations of the opposite phases displaced in the X-axis direction of one and the other vibrating arms of the driving-side tuning fork are substantially equal to the resonance frequencies of the bending vibrations having the opposite phases in the X-axis direction of the vibrating arm. Since the resonance frequencies of the torsional vibrations of opposite phases displaced about the Y 'axis of one and the other vibrating arms of the side tuning fork are made different, when the driving side tuning fork is driven to resonance, the detection side tuning fork has Y The opposite-phase torsional vibrations displaced around the '-axis and the opposite-phase bending vibrations in the X-axis direction generated on one and the other vibrating arms of the tuning-side tuning fork by the Coriolis force based on the acceleration in the Z'-axis direction are increased. With wear, it is possible to reduce the opposite phases of torsional vibrations displaced about Y 'axis. As a result,
It is possible to effectively detect the AC voltage generated by the opposite-phase bending vibrations in the X-axis direction while suppressing the influence of the AC voltage generated by the opposite-phase torsional vibration displaced around the Y 'axis, and to accurately detect the Z'-axis. It is possible to detect the acceleration in the direction.

According to the acceleration sensor of the third aspect, the resonance frequencies of torsional vibrations of opposite phases displaced around the Y 'axis of one and the other vibrating arms of the drive-side tuning fork and the opposite directions displaced in the X-axis direction. The resonance frequency of the phase bending vibration, the resonance frequency of the opposite phase torsional vibration displaced around the Y 'axis of one and the other vibrating arms of the detection side tuning fork, and the resonance frequency of the phase opposite bending vibration in the X axis direction Are separated from each other, so that when the driving-side tuning fork is driven in resonance, one and the other are caused by the torsional vibrations of opposite phases displaced around the Y 'axis and the Coriolis force based on the acceleration in the Z' axis direction. In contrast to the bending vibrations of the opposite phases in the X-axis direction generated in the vibrating arm of the first embodiment, the torsional vibrations of the opposite phases displaced around the Y'-axis can be suppressed. As a result, it is possible to effectively detect the AC voltage generated by the opposite-phase bending vibrations in the X-axis direction while suppressing the influence of the AC voltage generated by the opposite-phase torsional vibration displaced around the Y 'axis, and to accurately detect the AC voltage. The acceleration in the Z'-axis direction can be detected.

According to the acceleration sensor of the fourth aspect, since only the electrodes are formed on the front and back surfaces of the vibrating arm, the electrodes are easily formed and the manufacture is easy. According to the acceleration sensor according to the fifth aspect, since only one electrode is formed on the detection-side tuning fork on each of the front and back surfaces and both side surfaces of the pair of vibrating arms, the electrodes can be easily formed, and the manufacturing is easy. Easy.

According to the acceleration sensor of the sixth aspect, the torsional vibrations of opposite phases displaced around the Y 'axis of one and the other vibrating arms of the driving-side tuning fork are transmitted to the mechanical Q of the driving-side tuning fork.
The value can be transmitted to the detection-side tuning fork with maximum mechanical transmission efficiency without reducing the value, and the driving-side tuning fork and the coupling-side tuning fork can be easily integrated with the coupling, which facilitates manufacturing. .

According to the acceleration sensor of the present invention, the torsional vibrations of opposite phases displaced around the Y 'axis of one and the other vibrating arms of the drive-side tuning fork are transmitted to the mechanical Q of the drive-side tuning fork.
The value can be transmitted to the detection-side tuning fork with maximum mechanical transmission efficiency without decreasing the value, and the driving-side tuning fork and the coupling-side tuning fork are firmly integrated with a connector, and are excellent in vibration resistance.

According to the eighth aspect of the invention, a substantially U-shaped tuning-fork type crystal blank in which a vibrating arm and a supporting portion, which are not a bonding type as in the prior art, are integrated as a driving-side tuning fork and a detecting-side tuning fork, respectively. Is used, the acceleration can be detected with high accuracy over a wide temperature range with excellent temperature characteristics and little variation.

[Brief description of the drawings]

FIG. 1 is a perspective view of an acceleration sensor according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a cutting direction of a substantially U-shaped tuning fork crystal blank.

FIG. 3 is a schematic diagram showing a state of a drive electrode provided on a drive-side tuning fork.

FIG. 4 is a schematic diagram showing a state of a detection electrode provided on a detection-side tuning fork.

FIG. 5 is a schematic view showing pinpoint support positions of a substantially U-shaped tuning fork-shaped quartz blank.

FIG. 6 is a schematic view of a substantially U-shaped tuning fork-shaped crystal blank for explaining a vibrating node.

FIG. 7 is a schematic diagram showing dimensions and cut axes of a sample of a substantially U-shaped tuning fork-shaped quartz blank.

FIG. 8 is a characteristic diagram showing a difference in mechanical Q value due to a difference in a pinpoint support position of the acceleration sensor of the present invention.

FIG. 9 is a schematic diagram illustrating the principle of acceleration detection in the acceleration sensor according to the first embodiment of the present invention.

FIG. 10 is a schematic diagram showing an operation of acceleration detection in the acceleration sensor according to the first embodiment of the present invention.

FIG. 11 is a perspective view showing an acceleration sensor according to a second embodiment of the present invention.

FIG. 12 is a perspective view showing an acceleration sensor according to a third embodiment of the present invention.

FIG. 13 is a perspective view showing an acceleration sensor according to a fourth embodiment of the present invention.

FIG. 14 is a schematic diagram showing a cutting direction of a quartz crystal blank of an acceleration sensor according to a fifth embodiment of the present invention.

FIG. 15 is a schematic diagram of an acceleration sensor according to a fifth embodiment of the present invention.

FIG. 16 is a perspective view showing an example of a conventional acceleration sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Drive side tuning fork 22 Electrode 23 Support part 24 One vibrating arm 25 The other vibrating arm 26 Detection side tuning fork 27 Electrode 28 Support part 29 One vibrating arm 30 The other vibrating arm 31 Coupler 32 Joining part including vibrating node 33 Vibration Joints including nodes 36a to 36d Driving electrodes 37a to 37d Driving electrodes 38, 39 Common lines 40a to 40d Detection electrodes 41a to 41d Detection electrodes 42, 43 Common lines 31A Connectors 23a, 28a Through holes 23b, 28b Through holes 50a to 50d Detection electrodes 51a to 51d Detection electrodes

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Toshihiko Ichise 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Atsushi Otomo 1275-2 Kamihirose, Sayama City, Saitama Prefecture Nippon Dempa Kogyo Co., Ltd.Sayama Office (72) Inventor Jira Ota 12275-2 Kamihirose, Sayama City, Saitama Prefecture Nippon Dempa Industry Co., Ltd. 72) Inventor Koichiro Ota 12275-2 Kamihirose, Sayama City, Saitama Prefecture Nippon Denpa Kogyo Co., Ltd., Sayama Plant (72) Inventor Minoru Ishihara 125-2 Kamihirose, Sayama City, Saitama Prefecture Nippon Dempa Kogyo Co., Ltd., Sayama Plant (56) References JP-A-7-260488 (JP, A) JP-A-7-260489 (JP, A) JP-A-7-260491 (JP, A) JP-A-4-324311 (JP, A) JP-A-60-73414 (JP, A) JP-A-3-291517 (JP, A) JP-A-3-113310 (JP, A) JP-A-4-361165 (JP JP, A) JP-A-54-148392 (JP, A) JP-A-56-136014 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 19/56 G01P 9/04

Claims (8)

(57) [Claims] 1. A new crystal axis X, Y ', and Z' rotated around the X axis of the crystal axes X, Y, and Z are respectively cut out in the X, Y 'plane with the Y' axis direction as a longitudinal direction. Electrodes are arranged on the peripheral surfaces of the one and the other vibrating arms of a substantially U-shaped tuning fork-shaped quartz blank, each having a shape in which one and the other symmetric vibrating arms of a rectangular cross section are connected in parallel and integrally by a support portion. An acceleration sensor in which first and second tuning-fork type quartz vibrators are fixed to the support portion via a connector in a state where the first and second tuning-fork type quartz vibrators face each other in parallel with each other. By applying an AC voltage through the first and second vibrating arms.
A drive-side tuning fork that generates torsional vibrations of opposite phases displaced around an axis, wherein the second tuning-fork type quartz vibrator propagates from the first tuning-fork type quartz vibrator via the coupler And the other vibrating arm, which is generated by Coriolis force based on the torsional vibration displaced around the Y 'axis and the acceleration in the Z' axis direction, of the one and other vibrating arms in the opposite phase in the X axis direction. An acceleration sensor characterized in that it is a tuning-side tuning fork for acceleration detection that detects an AC voltage generated by bending vibration via an electrode. 2. The resonance frequencies of torsional vibrations of opposite phases displaced around the Y 'axis of one and the other vibrating arms of the drive-side tuning fork and opposite to each other in the X-axis direction of the one and the other vibrating arms of the detection-side tuning fork. The resonance frequency of the phase bending vibration is approximately equal,
In addition, the resonance frequencies of the opposite-phase bending vibrations displaced in the X-axis direction of the one and the other vibrating arms of the drive-side tuning fork and the opposite ones displaced around the Y 'axis of the one and the other vibrating arms of the detection-side tuning fork. 2. The acceleration sensor according to claim 1, wherein the vibrating arm of the drive-side tuning fork and the vibrating arm of the detection-side tuning fork are set to have different shapes and sizes so that the resonance frequency of the torsional vibration of the phase is different. 3. The resonance frequencies of bending vibrations of the opposite phases displaced in the X-axis direction of one and the other vibrating arms of the drive-side tuning fork, and torsional vibrations of the opposite phase displaced around the Y 'axis, and of the detection-side tuning fork. The driving side so that the resonance frequency of the bending vibration of the opposite phase in the X-axis direction of the one and the other vibrating arms and the resonance frequency of the torsional vibration of the opposite phase displaced around the Y 'axis are different from each other. The acceleration sensor according to claim 1, wherein the vibrating arm of the tuning fork and the vibrating arm of the detection-side tuning fork are set to have different shapes and sizes. 4. An electrode disposed on the peripheral surface of one and the other vibrating arms of the drive-side tuning fork is divided into three in the circumferential direction on the front and back surfaces of the one and the other vibrating arms when viewed in the Z 'axis direction. Each of the one and the other vibrating arms is divided into three, and the outer electrode is an outer electrode, the inner electrode is an inner electrode, the inner electrode is an inner electrode, and the inner electrode is an inner electrode. When the inner electrode on the front surface, the outer electrode on the front surface, the inner electrode on the back surface of the one vibrating arm, the inner electrode on the back surface, the outer electrode on the back surface, and the inner electrode on the front surface of the other vibrating arm are commonly connected, and the surface of the other vibrating arm is 2. The acceleration sensor according to claim 1, wherein the inner electrode, the outer surface electrode, the inner rear electrode, and the inner rear electrode, the outer rear electrode, and the inner front electrode of one vibrating arm are commonly connected. 5. An electrode provided on the peripheral surface of one and the other vibrating arms of the detecting-side tuning fork has four electrodes on the four peripheral surfaces on the front and back sides and on both sides of the one and the other vibrating arms when viewed in the Z'-axis direction.
Are provided in a state divided into four in the circumferential direction at two ridge lines, and the front and back electrodes of the one vibrating arm and the both side electrodes of the other vibrating arm are connected in common, and the surface of the other vibrating arm is connected. The acceleration sensor according to claim 1 , wherein the back electrode and both side electrodes of the one vibrating arm are connected in common. 6. The connector has a columnar shape with both end surfaces having an area, and both end surfaces are bonded to a surface partially including a vibrating node generated in a supporting portion of the drive-side tuning fork and the detection-side tuning fork. The acceleration sensor according to claim 1, wherein 7. The drive-side tuning fork and the detection-side tuning fork each have a through-hole having a certain area partially including a vibrating node generated in the support portion, and the connector has a columnar shape. 2. The acceleration sensor according to claim 1, wherein the first through-hole and the second through-hole are adhered to the supporting portions of the driving-side tuning fork and the detection-side tuning fork. 8. An electrode is formed on the peripheral surface of said one and other vibrating arms of a substantially U-shaped tuning fork-shaped quartz blank having a shape in which one and the other symmetric vibrating arms of a rectangular cross section are connected in parallel and integrally by a support portion. First and second respectively arranged
An acceleration sensor in which the tuning fork-shaped quartz resonator of the first aspect is fixed to the support portion via a connector in a state where the tuning fork-shaped quartz resonators are faced in parallel with each other, and an AC voltage is applied to the first tuning fork-shaped quartz resonator through an electrode. A drive-side tuning fork that generates torsional vibrations of opposite phases that are displaced around the longitudinal direction of one and the other vibrating arms by being applied, and the second tuning-fork type quartz vibrator passes through the coupler. Opposite torsional vibrations displaced around the longitudinal direction of the one and other vibrating arms propagated from the first tuning-fork type quartz vibrator and acceleration in a direction orthogonal to the direction in which the one and other vibrating arms are arranged A tuning fork for acceleration detection, which detects, via an electrode, an AC voltage generated by bending vibrations of opposite phases in the arrangement direction of one and the other vibrating arms generated by the Coriolis force based on An acceleration sensor according to claim.