JPH11271065A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently convert the Coriolis force into a sensitivity to enable the S/N improvement in an angular velocity sensor having an oscillator having four beams. SOLUTION: An oscillator 1 has a comb type tuning fork having four parallel beams 2-5 whose ends at one side are commonly supported by a coupling 6, the inner pair of beams 3, 4 are driving beams, and outer pair of beams 2, 5 are detecting beams. The oscillator 1 is supported by a torsion beam 8 which is located on the center line of the oscillator 1, say, z-axis and has a narrower width in the y-axis direction than the remove of the inner pair of beams 3, 4. Upon the input of an angular velocity around the z-axis, the adjacent beams 2-5 oscillate mutually reverse in the x-axis direction and the sizes of the oscillator 1 and torsion beam 8 are selected so that the ratio of the amplitude XU of the inner pair of beams 3, 4 to that XS of the outer pair of beams 2, 5 is 10 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor provided with a vibrator having a comb-shaped tuning fork shape having four beams and performing driving and detection with separate beams.

[0002]

2. Description of the Related Art Conventionally, as this kind of angular velocity sensor, one disclosed in Japanese Patent Application Laid-Open No. 8-278141 has been proposed. This is the outer two beam portions of a comb-shaped composite tuning fork (a so-called four-legged vibrator) having four parallel beam portions (oscillating arms) and a support portion that supports one end of the beam portions in common. Are used as drive beams (drive-side tuning forks), and the two inner beams are used as detection beam portions (detection-side tuning forks) for driving / detection.

The driving beam is excited in the direction in which the beams are arranged, and when an angular velocity is input about a predetermined axis, the vibration of the detecting beam in a direction orthogonal to the excitation direction of the driving beam is received. And the angular velocity is detected. This 4
Because the leg vibrator separates the beam for driving and for detecting,
It is said that a higher S / N can be obtained as compared with a two-leg vibrator (tuning fork).

[0004]

Here, in the above-described angular velocity sensor of the four-legged vibrator type, since the driving beam and the detecting beam are separated as described above, the driving beam is used. Unnecessary vibrations such as vibrations from the beam are not easily transmitted to the detection beam portion, and the detection beam portion is unlikely to vibrate except when an angular velocity is input, that is, when no Coriolis force is input. Therefore, noise N due to unnecessary vibration can be reduced.

On the other hand, since vibration is unlikely to occur, the amplitude of the detecting beam portion at the time of Coriolis force input (at the time of angular velocity input) becomes small, and sensitivity (gain of sensitivity) S becomes small. There is a possibility that a problem that N cannot be obtained may occur. By the way, when the inventor made a trial study of a four-legged vibrator based on the above-mentioned conventional technology, it was not possible to obtain a sufficient S / N, and rather, it was one digit smaller than the two-legged vibrator type. Met.

Accordingly, in order to improve the sensitivity S, it is necessary to increase the amplitude of the detection beam at the time of inputting the Coriolis force. No mention is made of a vibrator structure, a vibrator supporting method, or the like that increases the amplitude of the vibrator. In view of the above, the present invention provides an angular velocity sensor having a comb-shaped tuning fork-shaped vibrator having four beams, which enables efficient conversion of Coriolis force into sensitivity and further improvement in S / N. Aim.

[0007]

The inventor of the present invention first notices that there are two vibration modes (detection resonance modes) for detecting an angular velocity when an angular velocity is input in a quadruple vibrator type angular velocity sensor. did. That is, in the four-legged vibrator, one of the inner pair and the outer pair of the four beam portions is a driving beam portion, and the other pair is a detection beam portion. When the driving beams are driven and vibrated in a predetermined direction in opposite phases to each other (driving resonance mode), when the angular velocity is input, the driving beams vibrate in a direction opposite to the driving vibration direction by Coriolis force.

Therefore, the connecting portion connecting the beam portions is bent, and vibration is coupled to the detecting beam portion. As described above, the vibration due to the Coriolis force input to the driving beam is transmitted to the detecting beam, and the four beams vibrate in synchronization with each other in a direction orthogonal to the driving vibration direction. This vibration is the detection resonance mode. Here, one detection resonance mode is
This is a mode in which adjacent beam portions of the four beam portions arranged in parallel vibrate in directions opposite to each other (see FIG. 6A described below, hereinafter referred to as a first detection resonance mode). The detection resonance mode is such that when four beams arranged in parallel form one set of two beams on one side and one set of two beams on the other side from the center, they vibrate in the same direction within the group, and In the modes that vibrate in opposite directions (see FIG. 6B described later,
Hereinafter, referred to as a second detection resonance mode).

In each of these detection resonance modes, a desired detection resonance mode can be realized by appropriately setting the shape of the vibrator, for example, the width and length of the beam. Then, for each of the detection resonance modes, one of the inner pair and the outer pair of the four beam portions is set to one of the driving beam portion and the other to the other.
A transducer structure capable of improving S / N was studied using the pair as a detection beam.

It is considered that the vibration energy of the driving beam portion and the detection beam portion is dispersed, so that the amplitude of the detection beam portion becomes insufficient. As a result of focusing on the ratio XU / XS or XS / XU between the amplitude XU of the pair and the amplitude XS of the pair of outer beams, it was found that this ratio is correlated with the gain S of the sensitivity. .

[0011] Then, according to each detection resonance mode, the first
If the ratio XU / XS is set to 10 or less in the second detection resonance mode, and the ratio XS / XU, which is the reverse ratio to the first detection resonance mode, is set to 10 or less in the second detection resonance mode, It has been found that a practical level of S / N that is one digit higher than that of the four-leg transducer type can be realized. Claim 1
The invention of claim 14 is based on the above findings.

That is, according to the first aspect of the present invention,
In the xyz rectangular coordinate system, four beam portions (2 to 5) arranged in parallel in the y-axis direction, two on each side of the z-axis, and four beam portions (2 to 5) extending in the y-axis direction. ), A vibrator (1) formed in a comb-shaped tuning fork shape having a connecting portion (6) for connecting and supporting one end portion of (1). One of the pairs (2, 5) is a driving beam (3, 4), the other pair is a detecting beam (2, 5), and the driving beam is a driving beam. Driving means (20, 60, 61) for exciting the parts in the opposite phase in the y-axis direction to drive and vibrate are provided, and the detection beam part is generated when an angular velocity about the z-axis is input. X
Angular velocity detection means (25 to 27, for detecting angular velocity by detecting vibrations having opposite phases in the axial direction as detection vibrations);
63, 64), ie, 4
In an angular velocity sensor of a leg vibrator type, when an angular velocity is input, adjacent beam portions in the beam portions (2 to 5) vibrate in opposite directions in the x-axis direction, and a pair of inner beams vibrate in the x-axis direction. The dimension of the vibrator is set so that the ratio XU / XS between the amplitude XU of the beam portion and the amplitude XS of the pair of outer beam portions is 10 or less.

In the present invention, the detection resonance mode for detecting the angular velocity uses the first detection resonance mode, in which the amplitude XU of the pair of inner beams (3, 4) and the pair of outer resonance beams are used. Ratio XU / XS of amplitude XS of beam part (2, 5)
Is set to be 10 or less, the mechanical impedance can be reduced, and the vibration due to the Coriolis force input to the driving beams (3, 4) can be efficiently detected. 2, 5) to improve sensitivity and S /
N can be improved.

According to a second aspect of the present invention, in the four-legged vibrator type angular velocity sensor, when the angular velocity is input, two beams (2, 3) on one side of the z-axis out of the four beams are used. The two (4, 5) sides vibrate in opposite directions in the x-axis direction, and the amplitude XU of the pair of inner beams and the amplitude XS of the pair of outer beams in the vibration in the x-axis direction. The dimension of the vibrator is set so that the ratio XS / XU with respect to is not more than 10.

In the present invention, the detection resonance mode for detecting the angular velocity uses the second detection resonance mode, and in that mode, the amplitude XU of the pair of inner beams and the amplitude XS of the pair of outer beams are used in the mode. The dimensions of the vibrator are set so that the ratio XS / XU of the vibrator is 10 or less.
An effect equivalent to that of the described invention can be obtained. In addition, as a result of studying the method of supporting the vibrator, a torsion beam having a width smaller than the arrangement interval of the pair of inner beams was arranged on the center line of the vibrator, and the vibrator was supported via the torsion beam. It was found that the S / N could be improved by doing so. The inventions described in claims 3 and 4 are based on knowledge of the above-mentioned supporting method.

That is, according to a third aspect of the present invention, in the four-legged vibrator type angular velocity sensor, the vibrator (1) comprises:
a connecting portion (6) located on the z-axis and extending in the z-axis direction;
And is supported by torsion beams (8, 50, 51) whose width in the y-axis direction is smaller than the arrangement interval of the pair of inner beam portions (3, 4). And the dimensions of the vibrator and the torsion beam are set such that the ratio XU / XS is 10 or less in that mode.

In the present invention, since the vibrator (1) is supported by the connecting portion (6) by the thin torsion beams (8, 50, 51), the connecting portion (6) is moved in the x-axis direction when an angular velocity is input. When bending, the connecting portion bends around the torsion beam, so that the bending is not hindered. Therefore, the mechanical impedance can be further reduced as compared with the case where there is no torsion beam, and the amplitude of the detection vibration of the detection beam portion coupled from the driving vibration can be increased. In addition to the effect of the invention according to claim 1, S / N can be more effectively improved.

According to a fourth aspect of the present invention, in the quadruple vibrator type angular velocity sensor, the vibrator (1) is connected to the connecting portion (6) so as to be located on the z-axis and extend in the z-axis direction. They are connected and supported by torsion beams (8, 50, 51) whose width in the y-axis direction is narrower than the arrangement interval of the pair of inner beams (3, 4). It is characterized in that the vibrator vibrates in the detection resonance mode and the dimension of the vibrator is set so that the ratio XS / XU is 10 or less in that mode.

According to the present invention, it is possible to provide an angular velocity sensor having the effect of the torsion beam described above in addition to the effect of the second aspect of the present invention. Further, the invention according to claim 5 is characterized in that the pair of inner beams (3,
The distance WU between 4) and the distance W between the pair of outer beams (2, 5).
The ratio WS / WU to S is set to 2.5 or less. That is, by bringing WU and WS closer to each other, a pair of inner beams (3, 4) and a pair of outer beams (2,
By matching or approaching the rotational vibration efficiency (moment of inertia) of 5), the mechanical impedance of the vibrator is reduced, and the response by Coriolis force is improved.

Accordingly, the rotational torsional vibration generated when the Coriolis force is input to the inner pair or the outer pair of beams easily causes the rotational torsional vibration of the outer pair or the inner pair of beams. In addition, vibration energy due to Coriolis force can be efficiently transmitted, and high sensitivity can be obtained. The ratio WU / HU of the distance WU between the pair of inner beams (3, 4) and the width HU of the pair of inner beams (3, 4) is 2.5 or more. It is characterized by being 100 or less. That is, in order to increase the rotational torsional force (axial torque) for vibrating the pair of outer or inner beams on the detection side, the Coriolis of the pair of inner or outer beams on the drive side is used. By separating the point of force where the force acts from the approximate center axis between the pair of beams, the amplitude of the pair of outer or inner beams on the detection side during Coriolis input is increased, that is, high sensitivity is achieved. Obtainable. If the ratio WU / HU is 100 or more, the function as a tuning fork is reduced, and a sufficient drive amplitude cannot be obtained.

Further, the invention according to claim 7 is characterized in that the torsion beam (50, 51) is formed integrally with the vibrator (1) from the piezoelectric body, thereby improving the S / N at low cost. It is possible to provide an improved angular velocity sensor. The invention according to claim 8 is characterized in that the torsion beam (8) is formed separately from the vibrator (1) and is joined to the vibrator (1). the order of such can be manufactured with high durability material, rather high reliability, it is possible to provide an angular velocity sensor having improved S / N.

According to a ninth aspect of the present invention, the torsion beams (8, 50) are formed so as to extend from the connecting portion (6) in a direction opposite to the four beams (2 to 5) in the z-axis direction. According to another aspect of the present invention, there is provided a torsion beam configuration according to the seventh and eighth aspects. Also, in the invention according to claim 10, the torsion beam (51) is connected to the connecting portion (6) by z
Characterized in that they are formed so as to extend in the same direction of the four beam portions (2 to 5) in the axial direction,
It is possible to easily maintain the center of gravity of the vibrator (1), to be strong against external vibrations, and to be excellent in space efficiency.

Further, according to the present invention, the torsion beam (50, 51) is connected to the connecting portion (6) by the beam portion (2 to 2).
It is characterized in that it is formed in the same and opposite directions as 5), and can be made resistant to external impact. In the invention according to claim 12, the resonance frequency of the vibration mode in the y-axis direction is different between the pair of inner beams (3, 4) and the pair of outer beams (2, 5). By making the two pairs of resonance frequencies different from each other, the bending vibration of the inner pair or the outer pair of beam portions is transmitted to the outer pair or the inner pair of beam portions. However, the outer pair or the inner pair of beam portions do not bend or vibrate almost completely, so that the influence of the driving vibration is sufficiently reduced, the noise N can be reduced, and the S / S
N can be improved.

According to a thirteenth aspect of the present invention, a ratio of a resonance frequency fd of driving vibration of the driving beam portions (3, 4) to a resonance frequency fs of detection vibration of the detecting beam portions (2, 5) is provided. f
d / fs is 0.8 ≦ fd / fs ≦ 0.99 or 1.0
1 ≦ fd / fs ≦ 1.2, wherein the ratio fd / fs is within the above range to suppress the coupling between the drive resonance mode and the detection resonance mode,
S / N can be improved.

According to a fourteenth aspect of the present invention, the driving beams (3, 4) are provided with a monitoring means (21) for monitoring the driving vibration, and the driving means is provided with the monitoring means (21) for monitoring the driving vibration. The self-excited vibration of the driving beam portion is performed based on the monitor signal of (1), and a stable driving vibration can be obtained with respect to a temperature change or the like. In addition, the code | symbol in the parenthesis of each said means shows the correspondence with the concrete means of embodiment mentioned later.

[0026]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. In each of the drawings described in the embodiments below, each electrode described below shows an external appearance, and for convenience, is hatched with diagonal lines, but does not show a cross section. (First Embodiment) The basic configuration of this embodiment is shown in FIG.
FIG. 1 is a perspective view of the angular velocity sensor according to the present embodiment. Reference numeral 1 denotes a vibrator having four quadrangular prism-shaped beams 2, 3, 4, and 5 arranged substantially in parallel, a pair of inner beams 3, 4 being a driving beam, and a pair of outer beams. The parts 2 and 5 are configured as detection beam parts. Each of the beam portions 2 to 5 has one end portion connected to a common connecting portion 6.
The vibrator 1 has a comb-shaped tuning fork shape.

Here, as shown in FIG. 1, the longitudinal direction of the connecting portion 6, that is, the arrangement direction of the beam portions 2 to 5, is set to the y axis, and the beam portions 2 to 5 are set.
The xyz orthogonal coordinate system is configured with the longitudinal direction of the z axis as the z-axis and the thickness directions of the beams 2 to 5 and the connecting portion 6 as the x-axis. here,
The z-axis is located at the center between the pair of inner beams 3 and 4.
Hereinafter, description will be made based on this xyz rectangular coordinate system. Hereinafter, the x-axis direction refers to a direction parallel to the x-axis, and the same applies to the y-axis and the z-axis.

The dimension of the connecting portion 6 in the z-axis direction is larger between the pair of inner beams 3 and 4 than between the pair of outer beams 2 and 5. In other words, the length of the pair of inner beams 3, 4 in the z-axis direction is equal to the length of the pair of outer beams 2, 5,
Is shorter than the length. The beams 2 to 5 and the connecting portion 6 are integrally formed by machining a piezoelectric body such as PZT by dicing or the like. The vibrator 1 is polarized in the x-axis direction, as indicated by a white arrow shown in FIG.

Reference numeral 7 denotes a support portion, which has a substantially D-shape with a narrow central portion. The narrow portion is formed as a torsion beam 8, and a portion located on one end side of the torsion beam 8 is a connecting portion 6. The connection portion-side connection portion 7a fixed to the torsion beam 8 and the portion located on the other end side of the torsion beam 8 are configured as a substrate-side connection portion 7b fixed to a spacer 7c described later. Both the lengths of the connecting portions 7a and 7b in the y-axis direction are substantially equal to those of the connecting portion 6. The connecting portions 7a and 7b may not be provided, and may be directly connected to the connecting portion 6 and the spacer 7c at both ends of the torsion beam 8.

The torsion beam 8 is opposite to the beams 2 to 5 in the z-axis direction from a substantially central portion of the connecting portion 6 (that is, a substantially central portion between the supporting portions of the pair of inner beams 3 and 4). It is located to extend to the side. The width in the y-axis direction is smaller than the arrangement interval of the pair of inner beams 3 and 4. The support portion 7 is formed of a metal such as 42 alloy, for example, and as shown in FIG.
And the other side is bonded and fixed to the substrate (base) 10 via the spacer 7c by welding or the like.

Therefore, the vibrator 1 is supported in a floating state with respect to the substrate 10 via the support portion 7 and the spacer 7c. The central axis of the torsion beam 8 substantially coincides with the z-axis, in other words, the torsion beam 8 is located substantially on the center line of the vibrator 1. Further, as described later, the dimensional relationship between the vibrator 1 and the support portion 7 is such that the ratio XU / XS between the amplitude XU of the pair of inner beams 3 and 4 and the amplitude XS of the pair of outer beams 2 and 5 is 10. The resonance frequency of the vibration mode in the y-axis direction is set to
d) and the pair of outer beams 2, 5 (fd ₀ ) are different from each other, and a driving beam (in this example, a pair of inner beams).
The ratio fd / fs of the resonance frequency fd of the driving vibrations 3 and 4 and the detection resonance frequency fs of the detection vibrations of the detection beam portions (a pair of outer beams in this example) 2 and 5 is set to be within a predetermined range. , And so on.

Here, examples of specific dimensions of each part of the vibrator 1 and the support part 7 will be described with reference to the explanatory view of FIG. FIG. 2 shows the vibrator 1 and the support 7 viewed from the x-axis direction. First, in the z-axis direction, the length L1 of the pair of inner beams 3, 4 is 9 mm, and the pair of outer beams 2,
The length L2 of 5 is 11 mm, and the maximum dimension L3 of the entire vibrator 1 including the connecting portion 6 is 14 mm. Also, the z-axis direction dimensions L4 and L5 of the connection portion side connection portion 7a of the support portion 7 and the torsion beam 8 are each 1 mm.

On the other hand, in the y-axis direction, the dimension (beam width) W1 of each of the beams 2 to 5 is 1.2 mm.
Regarding the interval (slit width) between the adjacent beams 2 to 5, the interval W2 between the beams 2 and 3 and the interval W3 between the beams 4 and 5 are each 0.4 mm. , Beam 3
The distance W4 between the beam and the beam 4 is 4.0 mm. Therefore, the total length of the vibrator 1 is 9.6 mm. The dimension W5 in the y-axis direction of the torsion beam 8 is 2.0 mm. Further, the ratio WS / WU of the center axis interval WU of the pair of inner beams 3 and 4 to the center axis interval WS of the pair of outer beams 2 and 5 is set to about 1.6.

As described above, the dimension W5 of the torsion beam 8 in the y-axis direction is smaller than the distance W4 between the beam portions 3 and 4. That is, as described above, the width of the torsion beam 8 in the y-axis direction is smaller than the arrangement interval of the pair of inner beams 3 and 4. Further, the dimension (thickness) t of the vibrator 1 and the support portion 7 in the x-axis direction is 1.55 mm. next,
An electrode configuration formed on the vibrator 1 will be described. Here, the substrate 1 of the surface of the vibrator 1
The surface opposite to the X2 surface is defined as an X2 surface, and the surface opposite to the X2 surface is defined as an X1 surface. Also, in the vibrator 1, of the outer peripheral surfaces of the pair of outer beams 2 and 5 orthogonal to the y axis, the surface on the beam 2 side is set to Y.
The surface on the beam portion 5 side is defined as a Y1 surface.

In this embodiment, X1, X2, Y
Each electrode described later is formed on the Y1, Y2 plane, and the electrode configuration is shown in a developed view of FIG. In FIG. 3, (a)
Represents an X1 plane, (b) represents an X2 plane, (c) represents an Y1 plane, and (d) represents an electrode configuration on a Y2 plane. Hereinafter, description will be made with reference to FIG. Reference numeral 20 denotes a drive electrode (drive means), which is formed continuously from the outer peripheral side of the beam portion 3 to the outer peripheral side of the beam portion 4 through the connecting portion 6 on the X1 plane. Reference numeral 21 denotes a monitor electrode (monitor means) which is formed continuously from the inner peripheral side of the beam portion 3 through the connecting portion 6 to the inner peripheral side of the beam portion 4 on the X1 plane.

Reference numerals 22, 23 and 24 are angular velocity detecting electrodes (angular velocity detecting means) for detecting angular velocity. The angular velocity detection electrode 22 is formed over substantially the entire area of the beam 5 on the Y1 plane. On the other hand, the angular velocity detecting electrode 23 is formed over substantially the entire area of the beam 2 on the X1 plane, and the angular velocity detecting electrode 24 is formed substantially over the entire area of the beam 2 on the X2 plane. And
All the angular velocity detecting electrodes 22 to 24 are, as shown in FIG.
It is connected and conductive by the extraction electrodes 25, 26 and 27 formed on each surface. Angular velocity detecting electrodes 22 and 23
Are the extraction electrode 25 (on the Y1 plane) and the extraction electrode 26
(On the X1 plane), and the angular velocity detection electrodes 23 and 24 are connected via the extraction electrode 27 (on the Y2 plane).

28, 29, 30 and 31 are the above-mentioned driving,
This is a common electrode serving as a reference potential for the monitor and the angular velocity detection electrodes 20 to 24. The common electrode 28 is formed over substantially the entire area of the beam 5 on the X1 plane, and the common electrode 29 is formed over substantially the entire area of the beam 5 on the X2 plane. Further, the common electrode 30 is X2
From the substantially entire area of the beam portion 3 through the connecting portion 6 to the beam portion 4
Are formed continuously over substantially the entire area of the common electrode 3.
1 is formed over substantially the entire area of the beam portion 2 on the Y2 plane.

All the common electrodes 28 to 31 are
As shown in FIG. 3, the extraction electrodes 32 formed on each surface,
It is connected and conductive by 33, 34 and 35. The common electrodes 28 and 29 are connected via an extraction electrode 32 (Y1 plane), and the common electrodes 29 and 30 and the common electrode 31 are connected to extraction electrodes 33 and 34 (both X2 plane) and an extraction electrode 35 (Y2 plane). ) Is connected through.

On the X1 plane, pad electrodes 36 and 37 for wire bonding, which will be described later, are formed on the connecting portion 6. The pad electrode 36 is an angular velocity detecting electrode 2
The pad electrode 37 is located at the end of the extraction electrode 38 extending from the common electrode 28, and is formed wider than the extraction electrodes 26 and 38, respectively, in the middle of the extraction electrode 26 that conducts with the electrodes 2 to 24. Accordingly, the pad electrode 36 is electrically connected to the angular velocity detection electrodes 22 to 24, and the pad electrode 37 is electrically connected to the common electrodes 28 to 31.

The surface of the vibrator 1 that is orthogonal to the y-axis direction is the surface facing the beam 2 and the beam 3, and the beam 3 and the beam 4
No electrode is formed on the opposite surface between the beam portion 4 and the beam portion 5. Further, the drive electrode 20 and the monitor electrode 21,
The angular velocity detecting electrode 22 and the common electrodes 28 and 29 and the angular velocity detecting electrodes 23 and 24 and the common electrode 31 are formed with a gap therebetween, and are not conductive.

Further, as shown in FIG. 1, the substrate 10 is provided with terminals (lead terminals) T1 to T4 connected to a control circuit (control means) A10 described later. The terminal T1 is connected to the drive electrode 20 via the wire W1.
The terminal T2 is connected to the pad electrode 37 via the wire W2, the terminal T3 is connected to the monitor electrode 21 via the wire W3, and the terminal T4 is connected to the pad electrode 36 via the wire W4. . The connection of the respective wires is performed by, for example, wire bonding.

Next, the control circuit A10 provided in the angular velocity sensor of the present embodiment will be described with reference to the block diagram shown in FIG. The control circuit A10 mainly detects a drive system A11 that drives and vibrates the drive beams 3 and 4 by self-excited oscillation (self-excited vibration), and detects an angular velocity by detecting a detection vibration of the detection beams 2 and 5. It is divided into a detection system A12.
The vibrator 1 is connected to a circuit through a pad electrode 37 and is set at a reference potential.

The drive system A11 includes a charge amplifier 100 for converting an output (current) from the monitor electrode 21 into a voltage,
It comprises an AGC (auto gain control) circuit 101 provided after the charge amplifier 100. A
The GC circuit 101 applies the constant voltage to the drive electrode 20 while maintaining the feedback signal from the charge amplifier 100 to be a constant voltage.

The detection system A12 is provided after the current-voltage conversion circuit 102 for converting the output (current) from the angular velocity detection electrodes 22 to 24 into a voltage via the pad electrode 36, and the current-voltage conversion circuit 102 and thereafter. It comprises a synchronous detection circuit 103, an LPF (low-pass filter) 104 provided after the synchronous detection circuit 103, and a phase shift circuit 105 for shifting the feedback signal from the charge amplifier 100 by 90 °.

The output from the current-voltage conversion circuit 102 is output to the synchronous detection circuit 103 by the phase shift circuit 105.
After the synchronous detection based on the feedback signal shifted in step (1), the signal is smoothed by the LPF 104, converted into a DC voltage, and output as an angular velocity signal.
Next, the operation of the present embodiment will be described. First, X1
By applying an AC voltage between the drive electrode 20 and the common electrode 30 formed on the X2 plane and the X2 plane, uneven distribution of electric charges occurs in the driving beams (a pair of inner beams) 3 and 4.
Therefore, as shown in FIG. 5, the driving beam portions 3 and 4 perform bending vibrations symmetrical with respect to the center line of the vibrator in the y-axis direction (that is, in opposite phases to each other) (drive resonance mode). Resonates at.

The current proportional to the amplitude in the drive resonance mode is converted into a voltage by the charge amplifier 100 as an output from the monitor electrode 21 and monitored by the AGC circuit 101 so that this voltage, that is, the monitor signal is always constant. , A constant voltage signal (drive signal)
Apply to 0. Self-excited oscillation is performed in the above closed system,
Driving vibration is performed in the driving beams 3 and 4.

In this drive resonance mode, if the angular velocity input about the z-axis is 0, the detection beam portion (a pair of outer beam portions)
Since Nos. 2 and 5 hardly vibrate in the y-axis direction, the output from the angular velocity detecting electrodes 22 to 24, that is, the noise N is extremely small. For example, the amplitude of the detection beams 2 and 5 is about 1/200 compared to the amplitude of the driving beams 3 and 4. this is,
The length L of the driving beams 3 and 4 is set so that the resonance frequency of the driving resonance mode (driving vibration) differs from the resonance frequency of the mode in which the detecting beams 2 and 5 bend and vibrate in the y-axis direction.
This is because the dimensions and the shape are set such that the length L2 is different from the length L2 of the detection beam portions 2 and 5.

Therefore, in the drive resonance mode, substantially only the drive vibration of the drive beams 3, 4 is performed. When an angular velocity about the z-axis is input to the vibrator 1 during driving vibration, Coriolis force is generated in the vibrating driving beams 3 and 4. Then, in the x-axis direction orthogonal to the driving vibration direction (the direction of the driving resonance mode), the driving beams 3, 4 receive forces in directions opposite to each other. Due to this force, forces in directions opposite to each other in the x-axis direction (perpendicular to the plane of FIG. 5) are generated also in the vicinity of the support portion of the beam portion 3 and the vicinity of the support portion of the beam portion 4 of the connecting portion 6.

Accordingly, since the connecting portion 6 is twisted and flexed in the x-axis direction, the reaction beams 2 and 5 are also coupled and vibrate in opposite directions in the x-axis direction due to the reaction. The vibration mode (detection resonance mode) in the x-axis direction of FIG.
As shown in (1), the above-mentioned first detection resonance mode is set. That is, the adjacent beam portions 2 to 5 vibrate in opposite directions in the x-axis direction.

Here, the detection beams 2 and 5 have the opposite-phase vibrations in the x-axis direction as the detection vibrations, and the amplitudes proportional to the angular velocities are output (currents) from the angular velocity detection electrodes 22 to 24 as the currents. -The voltage is converted into a voltage by the voltage conversion circuit 102. This voltage is subjected to detection processing in the synchronous detection circuit 103 based on a feedback signal (monitor signal) from the phase shift circuit 105, and a signal smoothed through the LPF 104 is made the final output. This final output is D proportional to the angular velocity.
Generates C output (angular velocity signal).

The angular velocity detecting electrode 2 on the beam 2 side
The positional relationship between 3 and 24 and the common electrode 31 is the reverse of the positional relationship between the angular velocity detection electrode 22 and the common electrodes 28 and 29 on the beam 5 side. Therefore, in the above-described detection vibration in which the beam 2 and the beam 5 vibrate symmetrically (in opposite phases) in directions opposite to each other, the current detected from the angular velocity detection electrode 22 and the angular velocity detection electrodes 23 and 24 is It has the same phase.

By the way, according to this embodiment, since the first detection resonance mode is used, the amplitude XU of the driving beams 3, 4 and the detection beams 2, 5,
The dimensions of the vibrator 1 and the support portion 7 are set by simulation or the like so that the amplitude ratio XU / XS with respect to the amplitude XS is set to 10 or less. According to the study of the present inventors,
If the interval ratio WS / WU between the central axis interval WU of the pair of inner beams 3 and 4 and the central axis interval WS of the pair of outer beams 2 and 5 is within a predetermined range (about 1.6 in the present embodiment). It is confirmed that the amplitude ratio XU / XS can be set to 10 or less regardless of other dimensions.

Here, the relationship between the amplitude ratio XU / XS and the interval ratio WS / WU will be described with reference to the above-mentioned four-leg tuning fork vibrator of the prior art (JP-A-8-278141). The present embodiment is characterized in that in the detection resonance mode, the dimensions of the vibrator 1 and the torsion beam 8 are formed so that the amplitude ratio XU / XS becomes 10 or less, and the S / N ratio is improved. It is a point to be done.

The oscillator described in the above-mentioned prior art embodiment has an amplitude ratio XU / XS of 1 in the detection resonance mode.
It is as large as 0.7 or more. In the case of such a shape, when Coriolis force is input to the driving beam (driving vibrator), the amplitude in the direction orthogonal to the beam arrangement direction is very small. The amplitude of the vibrator is also reduced. This is the same even when the pair of outer beams is used for driving and the pair of inner beams is used for detection, or vice versa.

In this case, the amplitude at the time of Coriolis force input can be obtained only 1/10 or less, that is, the sensitivity can be obtained only 1/10 or less with respect to the conventional two-leg tuning fork. In addition, the effect of separating the driving beam and the detecting beam (vibrator) is also 1/5 that of a two-leg tuning fork. S / N improvement is not enough. Further, for example, the sensitivity S decreases. It becomes weaker to the external G by the decrease in the sensitivity S, and it becomes difficult to apply the sensor when, for example, the vehicle is considered.

As a result of studying the structure of the vibrator for the problem of sensitivity, in order to achieve higher sensitivity, the amplitude XU of the pair of inner beams in the detection direction in the detection resonance mode was determined.
And the amplitude ratio XU, which is the ratio of the amplitude XS of the pair of outer beams
/ XS is important. And the amplitude ratio X
As U / XS is reduced, vibration energy is also distributed to the detection beam (detection vibrator), and the amplitude of the detection beam in the detection direction increases when Coriolis force is input, that is, the sensitivity increases. , To solve the conventional problems and to improve the S / N of the sensor
Can be improved.

The mechanical impedance of the four-leg tuning fork is reduced,
As a result of studying from the viewpoint of improving the response to Coriolis force and improving the sensitivity, by reducing the amplitude ratio XU / XS, the driving tuning fork (driving beam portion) was obtained.
The vibration energy due to the Coriolis force is dispersed in the tuning fork (beam for detection) and the detection, and the sensitivity can be increased.
It has been found that as U / XS is reduced, the energy of the entire vibrator increases, that is, the mechanical impedance of the vibrator can be reduced. From the above, it can be seen that by reducing the amplitude ratio XU / XS, the mechanical impedance of the vibrator can be reduced and a high-sensitivity vibrator can be obtained. To obtain a high-sensitivity sensor, the amplitude ratio XU / XS must be 10 It must be:

Next, it was found that it is effective to reduce the above-mentioned interval ratio WS / WU as a specific method of reducing the amplitude ratio XU / XS. In order to reduce the amplitude ratio XU / XS (that is, to make the amplitude of the pair of inner beams 3, 4 and the pair of outer beams 2, 5 the same in the x-axis direction), these two pairs of beam portions 2 are used. Focusing on the idea of adjusting the easiness of the rotational vibration of ５5, that is, adjusting the inertia moment of both, and studying the adjustment of the length of each rotating arm, that is, the reduction of the interval ratio WS / WU. As a result, in order to realize a highly sensitive oscillator, the interval ratio WS / W
It has been found that it is desirable to make U 2.5 or less.

Further, a driving beam (a pair of inner beams) 3,
In order to increase the torsional rotation force, that is, the torque generated in the detection beam portions (a pair of outer beam portions) 2 and 5 when the Coriolis force is input to 4, an interval WU between the pair of inner beam portions 3 and 4 is increased. Preferably, the interval WU is the width HU of a pair of inner beams 3, 4 of the width W1 of each beam 2-5 shown in FIG.
However, it is desirable to set it to 2.5 or more.

In the embodiment described in the above prior art, the interval ratio WS / WU is 2.82, and since there is no torsion beam, the moment of inertia is large and the amplitude ratio XU
/ XS is about 10.7, and high sensitivity cannot be obtained. In contrast, in the present embodiment, the interval ratio WS /
Since the WU is set to 1.6 and the torsion beam 8 is provided, the amplitude ratio XU / XS is reduced to 1.6, and a sensitivity that is one order of magnitude higher than that of the related art can be obtained. In this structure, the vibration energy is efficiently transmitted to the detection beam portion to obtain a gain.

In the present embodiment, the effect of supporting the vibrator 1 by the torsion beam 8 is not only the effect of improving the sensitivity described above, but also enables the detection resonance mode to be stably realized. It also has an effect. Other than the torsion beam, for example, it is described that a lower portion of the vibrator is fixed to a rigid body, and a part of the above-described prior art example is provided with a cylindrical support hole in a thickness direction of the vibrator.

However, in the latter case, when a cylindrical pin is joined to this hole and the vibrator is supported from the side, the detection resonance mode described in the above prior art occurs, but it is proposed in the present invention. Detection resonance mode does not occur,
I cannot get stable. If it is further added, in the above-mentioned conventional technology, the method of supporting the vibrator is not specified, and the method of supporting the vibrator is an important element at the same level as the structure of the vibrator. Should be composed. The present embodiment provides a structure in which the method of supporting the vibrator and the structure of the vibrator are integrated.

The present embodiment is also characterized in that the vibrator 1 is supported by the torsion beam 8 located substantially on the center line of the vibrator 1. The torsion beam 8 is positioned so as to extend from a substantially central portion of the connecting portion 6 in the z-axis direction on the opposite side to the beam portions 2 to 5, and has a width in the y-axis direction that is equal to the width of the detection beam portion (one outside pair). (The beam portion) is smaller than the arrangement interval of the beams 2 and 5.

Therefore, as described above, when the connecting portion 6 bends in the x-axis direction when the angular velocity is input, the torsion beam 8
The bending is not hindered because the connecting portion 6 bends around the axis. Therefore, the amplitude of the detection vibration of the detection beam portions 2 and 5 can be increased. Further, in the present embodiment, the widths W1 of the drive beams 2, 5 and the detection beams 3, 4 are set to be the same,
In addition, the length L1 of the driving beams 2 and 5 is different from the length L2 of the detecting beams 3 and 4. Therefore, the resonance frequencies of the bending modes are different from each other in the driving resonance mode, and the driving vibration of the driving beams 3 and 4 (for example, fd = 643)
Even if 9 Hz is transmitted, the bending vibration (for example, fd ₀ = 4429 Hz) of the detection beams 2 and 5 is attenuated, and the S / N can be improved.

In the present embodiment, the ratio fd / fs of the resonance frequency of the drive vibration (drive resonance frequency) fd to the resonance frequency of the detection vibration (detection resonance frequency) fs is, for example, 1.
Since the dimensions of the vibrator 1 and the torsion beam 8 are set to be 04, the coupling between the drive resonance mode and the detection resonance mode can be suppressed, and the S / N can be improved. According to the study of the inventor, in order to suppress the coupling between the two modes, the ratio fd / fs is set to 0.8 ≦ fd / fs ≦
It is preferable that the relationship of 0.99 or 1.01 ≦ fd / fs ≦ 1.2 is satisfied.

Further, in the present embodiment, by arranging the torsion beam 8 in the direction opposite to the beam portions 2 to 5, the vibrator 1 and the torsion beam 8 can be formed separately and easily joined to each other. The weakest torsion beam can be formed of metal, and the impact resistance can be improved. In this embodiment, the vibrator 1 may be formed by etching another piezoelectric material, for example, Z-cut quartz, or dicing lithium niobate or langasite. Further, the present invention can be applied to a vibrator using a semiconductor.

In the present embodiment, even if the vibrator 1 is not supported via the torsion beam 8 and the bottom of the vibrator 1, that is, the connecting portion 6 is supported by clamping, the S / N is higher than the conventional one. Is obtained. Further, 20 may be used as a monitor electrode and 21 may be used as a drive electrode. In that case, it is needless to say that the connection to the control circuit A10 is appropriately changed.

Although the thickness of the vibrator 1 is not limited, the width (W1) of the beam is 0.01 to 5 mm based on physical limitations, driving frequency, and common sense from the viewpoint of manufacturing. Based on the premise, from the relationship between fs and fd, the thickness is
It is assumed that half to twice, that is, 0.005 to 10 mm. (Second Embodiment) In the first embodiment, as the detection resonance mode, the first detection resonance mode, that is, the mode in which the adjacent beams 2 to 5 vibrate in opposite directions in the x-axis direction is used. The present embodiment is different from the first embodiment in that the detection resonance mode is the second detection resonance mode shown in FIG.

In the second detection resonance mode of the present embodiment,
The inner pair of beams (driving beams) 3 and 4 vibrate in opposite phases to each other, and the outer pair of beams (detection beams) 2 and 5 vibrate in opposite phases to each other. The two beam portions 2, 3 on one side of the z-axis and the two beam portions 4, 5 on the other side vibrate in opposite directions in the x-axis direction. In order to realize the second detection resonance mode, the width W1 (see FIG. 2) of each of the beam portions 2 to 5 in the vibrator 1 may be smaller than that in the first embodiment. In this embodiment, the dimension of the vibrator 1 and the like is such that the ratio XS / XU between the amplitude XU of the pair of inner beams 3 and 4 and the amplitude XS of the pair of outer beams 2 and 5 is 10 or less. And the constraints described in the first embodiment are set.

In the second detection resonance mode, since the vibrator having the same size has a lower resonance frequency than the first detection resonance mode, the frequency of the vibrator can be reduced.
Therefore, it can be used in accordance with the configuration of the detection circuit (detection system A12 of the control circuit) requiring low-frequency vibration, the response of the sensor, and the like. (Third Embodiment) In the present embodiment, as compared with the first and second embodiments, the vibrator 1 is supported mainly by two torsion beams integrally formed with the vibrator instead of the support portion 7. It is different in the structure that was done. FIG. 7 shows the basic configuration of the present embodiment. FIG. 7 is a perspective view of the angular velocity sensor of the present embodiment. Hereinafter, points different from the first and second embodiments will be mainly described, and the same portions will be denoted by the same reference numerals in the drawings and description thereof will be omitted.

The vibrator 1 of the present embodiment has the same configuration as that of the first embodiment, and has four quadrangular prism-shaped beams 2, 3, 4, and 5 arranged substantially in parallel. Beams 3, 4
Are configured as driving beams, and a pair of outer beams 2 and 5 are configured as detection beams. One end of each of the beam portions 2 to 5 is fixedly supported by a common connecting portion 6, and the vibrator 1 has a comb-shaped tuning fork shape. Here, the relationship between the vibrator 1 and each axis of the xyz rectangular coordinate system is the same as in the first embodiment.

As shown in FIG. 7, there are two torsion beams 50 and 51 in this embodiment. The first torsion beam 50 is located on the opposite side of the beam portions 2 to 5 in the z-axis direction from a substantially central portion of the connecting portion 6 (that is, a substantially central portion between the support portions of the pair of inner beams 3 and 4). Located to extend. The second torsion beam 51 is positioned so as to extend from a substantially central portion of the connecting portion 6 in the same direction as the beams 2 to 5 in the z-axis direction. And both torsion beams 5
0 and 51 are located on the center line of the vibrator 1 (that is, the z-axis).

The ends of the torsion beams 50 and 51 on the side opposite to the connecting portion 6 are respectively formed as connecting portions 50a and 51a connected to a frame 52 described later. The portions of the two torsion beams 50 and 51 other than the connection portions 50a and 51a have a width in the y-axis direction smaller than the arrangement interval of the pair of inner beams 3 and 4 as in the first embodiment. .

The vibrator 1 of this embodiment is also composed of a piezoelectric material, as in the first embodiment. However, since the vibrator 1 and both torsion beams 50 and 51 are integrally formed, for example, a piezoelectric material such as an x-cut quartz crystal is used. Is preferably formed integrally by dicing. Note that the axis of the crystal is irrelevant to the xyz rectangular coordinate system, and is set to a desired direction. The vibrator 1 and the torsion beams 50 and 51 are coupled to the glass frame 52 by chemical bonding, and the vibrator 1 is in a floating state so as to be able to vibrate freely.

In the present embodiment, the first and second detection resonance modes can be used as the detection resonance mode. However, similar to the first and second embodiments, the first and second detection resonance modes correspond to the detection resonance modes to be used. Needless to say, the dimensions of the vibrator 1 and the torsion beams 50 and 51 can be set. Hereinafter, description will be made assuming that the second detection resonance mode is used.

Next, the configuration of the electrodes on the vibrator 1 will be described. The X1, X2, Y1, and Y2 planes of the vibrator 1 are the same as those in the first embodiment, and FIG.
1 plane, (b) X2 plane, (c) Y1 plane, (d) Y2 plane
2 shows an electrode configuration of a surface. Hereinafter, description will be made with reference to FIG.
Reference numerals 60 and 61 denote driving electrodes (driving means), which are formed on the outer peripheral portion of the beam portion 3 and the outer peripheral portion of the beam portion 4 on the X1 plane, respectively. Reference numeral 62 denotes a monitor electrode (monitor means), which is formed on the inner peripheral side of the beam portion 4 on the X1 plane.

Reference numerals 63 and 64 denote angular velocity detecting electrodes (angular velocity detecting means) for detecting angular velocity. Angular velocity detection electrode 63
Are formed over substantially the entire area of the beam section 5 on the Y1 plane, and the angular velocity detection electrodes 64 are formed over substantially the entire area of the beam section 2 on the Y2 plane. On the X1 plane, both drive electrodes 60 and 61 are formed by a lead electrode 65 formed on the connection part 6 and a lead electrode 66 formed on the connection part 6 and the torsion beam 51 by a pad electrode formed on the connection part 51a. 67 is electrically connected. In the X1 plane, the monitor electrode 62 is connected to the extraction electrode 6 formed from the connection portion 6 to the torsion beam 51.
8, the pad electrode 69 formed on the connection portion 51a
Is electrically connected to

The angular velocity detecting electrode 63 is connected to the extraction electrode 70 formed on the Y1 plane and the connecting portion 6 on the X1 plane.
And extraction electrode 71 formed on torsion beam 50
Is electrically connected to the pad electrode 72 formed on the connection portion 50a through the connection. On the other hand, the angular velocity detecting electrode 64
Is electrically connected to the pad electrode 75 formed on the connection portion 50a via the extraction electrode 73 formed on the Y2 surface and the extraction electrode 74 formed on the torsion beam 50 on the X1 surface. .

Reference numerals 76, 77, and 78 are common electrodes serving as reference potentials for the drive, monitor, and angular velocity detection electrodes 60 to 64. The common electrode 76 is formed continuously from substantially the entire area of the beam section 2 on the X1 plane to substantially the entire area of the beam section 5 through the connecting section 6, and the common electrode 77 is formed substantially on the X2 plane. It is formed continuously over the entire area and the connecting portion 6. In addition, the common electrode 78 is connected to the beam 3 on the X1 plane.
And is electrically connected to the common electrode 77 by a short-circuit electrode 78 a (see FIG. 7) formed on the surface of the beam 3 facing the beam 4 in the beam 3.

Each of the common electrodes 76 to 78 is conductive through an extraction electrode 79 formed on the Y1 plane.
6 is a pad electrode 8 formed on the connecting portion 50a via an extraction electrode 80 formed on the connecting portion 6 on the X1 plane.
1 electrically. Therefore, the pad electrode 67
, The pad electrode 69 is connected to the monitor electrode 62, the pad electrode 72 is connected to the angular velocity detection electrode 63, the pad electrode 75 is connected to the angular velocity detection electrode 64, and the pad electrode 81 is connected to the common electrodes 76 to 78. It will be in the form. These pad electrodes are connected to a control circuit (control means) B10 described later.
This is the part connected by wire bonding.
The electrodes 60 to 81 are formed by vapor deposition of Cr, Au, or the like.

Next, the control circuit B10 provided in the angular velocity sensor according to the present embodiment will be described with reference to the block diagram shown in FIG. The control circuit B10 performs an angular velocity detection by detecting a drive system B11 that drives and vibrates the drive beams 3 and 4 by self-excited oscillation (self-excited vibration) and a detection vibration of the detection beams 2 and 5. It is divided into a detection system B12.
The vibrator 1 is connected to the circuit from the pad electrode 81 by wire bonding or the like and is set at a reference potential.

The drive system B11 has the same configuration as the drive system A11, and includes a charge amplifier 100 and an AGC circuit 10.
And 1. Here, the output of the monitor electrode 62 is input to the charge amplifier 100 from the pad electrode 69, and a constant voltage is applied to the drive electrodes 60 and 61 from the AGC circuit 101 through the pad electrode 67 by a feedback signal.

The detection system B12 includes current-voltage conversion circuits 202a and 202b for converting outputs (currents) from the angular velocity detection electrodes 63 and 64 via the pad electrodes 72 and 75 into voltages.
A differential circuit 203 for subtracting outputs from the current-voltage conversion circuits 202a and 202b, a synchronous detection circuit 103 provided after the differential circuit 203, an LPF 104,
And a phase shift circuit 105. That is, as compared with the detection system A12, the difference is that there are two current-voltage conversion circuits and that the detection system A12 has the differential circuit 203.

Then, the current-voltage conversion circuits 202a,
02b is subtracted by a differential circuit 203, and, as in the first embodiment, the synchronous detection circuit 103
After the synchronous detection based on the feedback signal phase-shifted by the phase shift circuit 105, the LPF 104 smoothes the converted signal into a DC voltage and outputs it as an angular velocity signal.

Next, the operation of the present embodiment will be described. First, the drive electrodes 60 formed on the X1 plane and the X2 plane,
By applying an AC voltage between the common beam 61 and the common electrode 77, the driving beams 3, 4
However, as shown in FIG. 5, resonance occurs in the drive resonance mode. The amplitude in the drive resonance mode is monitored by monitoring the output from the monitor electrode 62 in the same manner as in the first embodiment, and self-oscillation is performed to drive and vibrate the drive beams 3 and 4.

Also in the present embodiment, the driving beam is driven so that the resonance frequency in the driving resonance mode (driving vibration) and the resonance frequency in the mode in which the detecting beam portions 2 and 5 bend and vibrate in the y-axis direction are different from each other. The length L1 of the parts 3 and 4 and the detection beam part 2,
Since the length L2 is set to be different from the length L2, if the angular velocity input about the z-axis is 0, the detection beams 2, 5 hardly vibrate in the y-axis direction, and the angular velocity detection electrode 63, The output from 64, the noise N, is very small. Therefore, in the drive resonance mode, substantially only the drive vibration of the drive beams 3, 4 is performed.

When an angular velocity about the z-axis is input to the vibrator 1 during the driving vibration, the Coriolis force generated in the vibrating driving beams 3 and 4 is generated as in the first embodiment. As a result, bending of the connecting portion 6 in the x-axis direction occurs, and opposite-phase vibrations (detection vibrations) of the detection beam portions 2 and 5 in the x-axis direction are coupled, and the second beam shown in FIG. A detection resonance mode occurs.

The detected vibration causes the angular velocity detecting electrode 6
A current proportional to the amplitude in the x-axis direction, that is, the angular velocity is generated from 3, 64. The current is applied to the pad electrode 72,
The voltage is converted to a voltage by the current-voltage conversion circuits 202a and 202b via the switch 75. In the case of the present embodiment, since the outputs from the angular velocity detection electrodes 63 and 64 are generated in opposite phases, a subtraction process is performed in the differential circuit 203 and a feedback signal (monitor signal) from the phase shift circuit 105 is output. ) Is detected by the synchronous detection circuit 103, and the LPF 1
The signal smoothed through the signal 04 is the final output. This final output produces a DC output (angular velocity signal) proportional to the angular velocity.

By the way, in the present embodiment, since the second detection resonance mode is used, the amplitude X
The amplitude ratio XS / XU between U and the amplitude XS of the detection beam portions 2 and 5
Is set to 10 or less, and the interval ratio WS / WU of the beam portions is set to be 10 or less.
The dimensions of the vibrator 1 and the torsion beams 50 and 51 are set. Also in the present embodiment, the torsion beam 50 substantially located on the center line of the vibrator 1
The support 51 allows the vibrator 1 to be supported without obstructing the bending of the connecting portion 6 when the angular velocity is input, and the amplitude of the detection vibration of the detection beam portions 2 and 5 can be increased. Therefore, also in this embodiment, a high S / N can be realized.

Further, in the present embodiment, since the vibrator 1 is supported by the torsion beams 50, 51 having both ends, the vibrator 1 is superior in impact resistance as compared with the cantilever support, and is driven by the two torsion beams 50, 51. System B11 and detection system B
Twelve wires can be separated, so that they have excellent electric noise resistance, and they are inexpensive because they are integrally formed of a piezoelectric body.

Also in this embodiment, the dimensions of the vibrator 1 and the torsion beams 50 and 51 are set so as to suppress the coupling between the driving resonance mode and the detection resonance mode. Note that, in the present embodiment, when the first detection resonance mode is used, each beam portion 2 is opposite to the above-described second embodiment.
The widths W1 to 5 (see FIG. 2) may be increased, and the dimensions may be set so that the ratio XU / XS is 10 or less, as in the first embodiment.

(Fourth Embodiment) FIG.
0 is shown. In the present embodiment, one torsion beam 90 integrally formed with the vibrator 1 extends from the connecting portion 6 in the same direction as the four beam portions 2 to 5 in the z-axis direction.
It is characterized by supporting the vibrator 1. The center axis (long axis) of the torsion beam 90 also substantially coincides with the z-axis, and is located substantially on the center line of the vibrator 1. The end of the torsion beam 90 on the side opposite to the connecting portion 6 is configured as a connecting portion 90a connected to the substrate or the frame as described in the first to third embodiments.
Then, in the portion other than the connection portion 90a, the width in the y-axis direction is smaller than the arrangement interval of the pair of inner beam portions 3 and 4.

The vibrator 1 is made of a piezoelectric material as described above, and has a comb-shaped tuning fork shape having beams 2 to 5 and a connecting portion 6. Further, the torsion beam 90 is integrally formed from the same piezoelectric material (for example, quartz) as the vibrator 1. The electrode configuration on the vibrator 1 is basically the same as that in the third embodiment, but since there is no torsion beam on the side opposite to the beam portions 2 to 5 as compared with the third embodiment, the pad electrode 72 ,
Reference numerals 75 and 81 are formed in the connecting portion 6, and the extraction electrodes 7
1, 74 and 80 are formed only in the connecting portion 6.

In this embodiment, as in the above-described embodiments, the dimensions are set so that the S / N ratio can be improved, and the effect of the torsion beam 90 can also be realized. Further, in the present embodiment, the torsion beam 90
Can be supported at the position of the center of gravity of the vibrator 1, and is excellent in external vibration. Further, since there is no torsion beam on the side opposite to the beam portions 2 to 5 and the configuration is high in space efficiency, the torsion beam can be lengthened, and the ratio XU / XS or XS / XU can be reduced. That is, there is a feature that the sensitivity S can be increased.

(Other Embodiments) In the above embodiments, a pair of inner beams 3 and 4 are used as driving beams, and a pair of outer beams 2 and 5 are used as detecting beams. The pair of inner beams 3 and 4 is used as a detection beam, and the pair of outer beams 2 and
The same effect can be obtained by using 5 as a driving beam.

The shape of the vibrator 1 may be as shown in FIG. In FIG. 11, a non-vibration part M1 which is a part that does not vibrate and extends in the same direction as each of the beam parts 2 to 5 from the connecting part 6 is formed between the pair of inner side beam parts 3 and 4. By forming the non-vibrating portion M1, the forming of the vibrator 1 is simplified.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing respective dimensions of a vibrator and a support unit of FIG. 1;

FIG. 3 is a developed view showing an electrode configuration on the vibrator of FIG.

FIG. 4 is a block diagram of a control circuit according to the first embodiment.

FIG. 5 is an explanatory diagram showing a drive resonance mode of the present invention.

FIG. 6 is an explanatory diagram showing a detection resonance mode of the present invention.

FIG. 7 is a perspective view illustrating a configuration of an angular velocity sensor according to a third embodiment of the present invention.

FIG. 8 is a developed view showing an electrode configuration on the vibrator of FIG. 7;

FIG. 9 is a block diagram of a control circuit according to the third embodiment.

FIG. 10 is a perspective view illustrating a configuration of an angular velocity sensor according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... vibrator, 2, 5 ... drive beam part, 3, 4 ... detection beam part, 6 ... connection part, 8, 90 ... torsion beam, 20,
60, 61: drive electrode, 21: monitor electrode, 25, 2
6, 27, 63, 64: angular velocity detection electrode; 50, first torsion beam; 51, second torsion beam.

Claims (14)

[Claims] 1. In an xyz rectangular coordinate system, at least four beam portions (2 to 5) arranged in parallel in the y-axis direction two on each side of the z-axis;
A vibrator (1) formed in a comb-shaped tuning fork shape having a connecting portion (6) for connecting and supporting one end of the beam portions (2 to 5).
In the four beam portions, one of the inner pair (3, 4) and the outer pair (2, 5) is used as one of the driving beam portions (3, 4), and One pair is a detection beam portion (2, 5), and the driving beam portion has a driving means (2) for driving and oscillating the driving beam portion in the y-axis direction in an opposite phase to each other.
0, 60, 61) are provided. The detection beam portion detects, as detection vibration, mutually opposite vibrations in the x-axis direction of the detection beam portion that occur when an angular velocity about the z-axis is input. An angular velocity sensor provided with angular velocity detecting means (25 to 27, 63, 64) for detecting the angular velocity, wherein when the angular velocity is input, adjacent beam parts of the beam parts (2 to 5) Vibrate in opposite directions in the x-axis direction, and in the vibration in the x-axis direction, the ratio XU / XS between the amplitude XU of the pair of inner beams and the amplitude XS of the pair of outer beams is The angular velocity sensor, wherein the size of the vibrator is set to be 10 or less. 2. In an xyz orthogonal coordinate system, at least four beam portions (2 to 5) arranged two in parallel on both sides of the z-axis in the y-axis direction, and extending in the y-axis direction,
A vibrator (1) formed in a comb-shaped tuning fork shape having a connecting portion (6) for connecting and supporting one end of the beam portions (2 to 5).
In the four beam portions, one of the inner pair (3, 4) and the outer pair (2, 5) is used as one of the driving beam portions (3, 4), and One pair is a detection beam portion (2, 5), and the driving beam portion has a driving means (2) for driving and oscillating the driving beam portion in the y-axis direction in an opposite phase to each other.
0, 60, 61) are provided. The detection beam portion detects, as detection vibration, mutually opposite vibrations in the x-axis direction of the detection beam portion that occur when an angular velocity about the z-axis is input. An angular velocity sensor provided with angular velocity detecting means (25 to 27, 63, 64) for detecting the angular velocity, wherein at the time of inputting the angular velocity, two of the four beam parts on one side of the z-axis are used. (2, 3) and the other two (4, 5) vibrate in opposite directions in the x-axis direction, and in the vibration in the x-axis direction, the amplitude XU of the pair of inner beams and the amplitude An angular velocity sensor, wherein the size of the vibrator is set such that a ratio XS / XU to an amplitude XS of a pair of outer beam portions is 10 or less. 3. In an xyz rectangular coordinate system, four beams (2) arranged two on each side of the z-axis in parallel with the y-axis direction.
5) and a connecting portion (6) extending in the y-axis direction and connecting and supporting one end of the four beam portions (2 to 5). In the four beam portions, one of an inner pair (3, 4) and an outer pair (2, 5) is used as one of the driving beam portions (3, 4), and A pair is a detection beam portion (2, 5), and the driving beam portion has a driving means (2) for exciting the driving beam portion in the y-axis direction in the opposite phase to each other to drive and vibrate.
0, 60, 61) are provided. The detection beam portion detects, as detection vibration, mutually opposite vibrations in the x-axis direction of the detection beam portion that occur when an angular velocity about the z-axis is input. An angular velocity sensor provided with angular velocity detecting means (25 to 27, 63, 64) for detecting the angular velocity, wherein the vibrator (1) is located on a z-axis and extends in a z-axis direction. And the torsion beams (8, 50, 51, 90) whose width in the y-axis direction is smaller than the arrangement interval of the pair of inner beams (3, 4). At the time of inputting the angular velocity, adjacent beam portions among the beam portions (2 to 5) vibrate in opposite directions in the x-axis direction, and the pair of inner beams in the vibration in the x-axis direction. Amplitude XU of the outer portion and amplitude XS of the pair of outer beams. An angular velocity sensor ratio XU / XS, characterized in that the dimensions of the vibrator and the torsion beam so as to be 10 or less is set for. 4. In an xyz rectangular coordinate system, four beam portions (2) arranged two on each side of the z-axis in parallel with the y-axis direction.
5) and a connecting portion (6) extending in the y-axis direction and connecting and supporting one end of the four beam portions (2 to 5). In the four beam portions, one of an inner pair (3, 4) and an outer pair (2, 5) is used as one of the driving beam portions (3, 4) and the other one is used. A pair is a detection beam portion (2, 5), and the driving beam portion has a driving means (2) for exciting the driving beam portion in the y-axis direction in the opposite phase to each other to drive and vibrate.
0, 60, 61) are provided. The detection beam portion detects, as detection vibration, mutually opposite vibrations in the x-axis direction of the detection beam portion that occur when an angular velocity about the z-axis is input. An angular velocity sensor provided with angular velocity detecting means (25 to 27, 63, 64) for detecting the angular velocity, wherein the vibrator (1) is located on a z-axis and extends in a z-axis direction. And the torsion beams (8, 50, 51, 90) whose width in the y-axis direction is smaller than the arrangement interval of the pair of inner beams (3, 4). When the angular velocity is input, two beams (2, 3) on one side of the z-axis and two beams (4, 5) on the other side of the four beam portions vibrate in opposite directions in the x-axis direction. And in the vibration in the x-axis direction, the amplitude XU of the pair of inner beams An angular velocity sensor, wherein the size of the vibrator is set such that a ratio XS / XU to an amplitude XS of the pair of outer beam portions is 10 or less. 5. A ratio WS / WU of a distance WU between the pair of inner beams (3, 4) and a distance WS between the pair of outer beams (2, 5) is 2.5 or less. The angular velocity sensor according to any one of claims 1 to 4, wherein: 6. A ratio WU / HU of a distance WU between the pair of inner beams (3, 4) and a width HU of the pair of inner beams (3, 4) is 2.5 or more and 100 or less. The angular velocity sensor according to any one of claims 1 to 5, wherein: 7. The torsion beam (50, 51, 9)
5. The angular velocity sensor according to claim 3, wherein the vibrator and the vibrator are integrally formed of a piezoelectric body. 6. 8. The vibrator (1), wherein the torsion beam (8) is formed separately from the vibrator (1) and is joined to the vibrator (1).
2. The angular velocity sensor according to 1. 9. The torsion beam (8, 50)
The angular velocity sensor according to claim 7, wherein the angular velocity sensor is formed so as to extend from the connection portion in a direction opposite to the four beam portions in the z-axis direction. 10. The torsion beam (51, 90).
9. The angular velocity sensor according to claim 7, wherein the at least one beam is formed so as to extend from the connection part in the same direction as the four beam parts in the z-axis direction. 10. . 11. The torsion beam (50, 51).
Are two and one of the torsion beams (51)
Extends in the same direction as the four beams (2 to 5) in the z-axis direction from the connecting portion (6), and the other torsion beam (50) extends in the z-axis direction from the connecting portion (6). 9. The device according to claim 7, wherein the plurality of beams are formed so as to extend in a direction opposite to the four beams.
2. The angular velocity sensor according to 1. 12. The method according to claim 1, wherein the resonance frequency of the vibration mode in the y-axis direction is different between the pair of inner beams (3, 4) and the pair of outer beams (2, 5). The angular velocity sensor according to any one of claims 1 to 11, wherein: 13. A ratio fd / fs of a resonance frequency fd of driving vibration of the driving beam portions (3, 4) to a resonance frequency fs of detection vibration of the detecting beam portions (2, 5) is 0.8. ≤ fd / fs ≤ 0.99 or 1.01 ≤ fd
The angular velocity sensor according to any one of claims 1 to 11, wherein a relationship of /fs≤1.2 is satisfied. 14. A driving means (21, 62) for monitoring the driving vibration is provided on the driving beam (3, 4).
The self-excited vibration of the drive beam portion based on a monitor signal from the monitor means (21, 62) in the drive vibration. The angular velocity sensor according to any one of the above.