JP2000009471A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the angular velocity detection precision by stabilizing the continuous vibration of a vibrator. SOLUTION: The angular velocity sensor is provided with a pair of x vibrators 2 and 3 that are located at symmetrical positions in reference to a point O, a connection beam 1 that is continuous to them and is deflected at least in x direction, a first support beam 4 that is continuous to it and includes first flexible beams 41 and 42 being deflected in x and y directions between the point O and the connection beam, and is symmetrical in reference to the point O, detection vibrators 5/6 that are symmetrical in reference to the point O, second support beams 7/8 that are continuous to these, include second flexible beams 71, 72/81, and 82 being deflected in y direction in reference to the point O, and are symmetrical in reference to the point O, an anchor 120 for supporting the first support beam 4 and the second support beams 7/8 at the point O, excitation means 10A and 10B for vibrating and driving the x vibrators 2 and 3 in inverse phase, and means 111 and 112 for detecting the y vibration of the detection vibrators 5/6. The detection vibrators 5/6 are separated in x direction from the y axis and are symmetrical in reference to the point O.

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 having a vibrating body floatingly supported on a substrate.
Although not intended to be limited to this, the present invention relates to an angular velocity sensor that electrically attracts / releases a floating semiconductor thin film formed by using a semiconductor microfabrication technique with a comb-shaped electrode and excites the x-direction.

[0002]

2. Description of the Related Art A typical type of angular velocity sensor has a pair of floating comb electrodes (a left floating comb electrode and a right floating comb electrode) on the left side and one set on the right side of a floating thin film. And two sets of fixed comb electrodes (a left fixed comb electrode and a right fixed comb electrode that mesh with and are parallel to each set of floating comb electrodes in a non-contact manner) as left floating comb electrodes / left fixed comb electrodes. By alternately applying a voltage between the space and the right floating comb electrode / the right fixed comb electrode, the floating thin film vibrates in the x direction. When an angular velocity of rotation about the z-axis is applied to the floating thin film, Coriolis force is applied to the floating thin film, and the floating thin film becomes
An elliptical vibration that vibrates also in the y direction. If the floating thin film is used as a conductor or an electrode is bonded, and a detection electrode parallel to the xz plane of the floating thin film is provided on the substrate, the capacitance between the detection electrode and the floating thin film becomes elliptical oscillation. Vibrates according to the y component (angular velocity component). By measuring the change (amplitude) of the capacitance, the angular velocity can be determined (for example, Japanese Patent Application Laid-Open Nos. 5-248873, 7-218268, 8-152327, and 9). -127148, JP-A-9-42
No. 973).

[0003]

In the conventional angular velocity sensor, the anchor portion is divided into multiple points, and since there is a distance between the anchor portions, compression or tension is applied when an external force such as a temperature change is applied to a beam spring portion for making the vibrator single vibration. Stress is applied. Therefore, the resonance frequency changes with the temperature, and the characteristic has hysteresis and discontinuous points. It reduces the accuracy of the sensor. For example, as disclosed in Japanese Patent Application Laid-Open No. Hei 7-218268, in a conventional angle sensor having multiple anchor portions, vibration during driving leaks to the vibration on the detection side due to the distance between the anchors, thereby lowering accuracy. It is considered that Further, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-218268, in the case where the fixed points of the driving vibration mode and the detection vibration mode do not match, the angular velocity detection accuracy is affected by mutual vibration leakage and external force. It is thought to decrease. Further, when the driving vibration mode includes a vibration component that reduces vibration due to Coriolis force, the angular velocity detection output is small. In some cases, the amplitude of the conventional vibrator is different between the + x direction and the −x direction, and the vibration is unstable, and the vibration may not be established as a sensor.

An object of the present invention is to stabilize continuous vibration of a vibrator and to increase angular velocity detection accuracy.

[0005]

(1) An angular velocity sensor according to the present invention includes a pair of x vibrators (2, 3) at symmetric positions with respect to a point O on an x, y plane; A connecting beam (1) distributed and symmetric with respect to the point O, continuous with each of the pair of x-vibrators (2, 3) and flexing at least in the x-direction; First bending in the x and y directions between connecting beam
First support beam symmetrical about point O, including flexible beams (41, 42)
(4); a detecting oscillator (5/6) symmetrical with respect to the point O; a second flexible beam (7
1,72 / 81,82), the second support beam (7 /
8); first support beam (4) and second support beam (7/8) at point O
Anchors (120) supporting the pair x transducers (2, 3), x
Exciting means (10A, 10B) driven to vibrate in the opposite phase to the direction; and means for detecting the y-direction vibration of the detecting vibrator (5/6) (11
1,112); In addition, in order to facilitate understanding, the reference numerals of the corresponding elements in the embodiments shown in the drawings and described later are added in the parentheses for reference.

According to this, the anchor (120) of one point O
Supports the pair of x-vibrators (2, 3) via the first support beam (4) and the connecting beam (1), and detects the vibrator via the second support beam (7/8). Since (5/6) is supported, that is, the fixed support point of the pair of x oscillators (2, 3) and the fixed support point of the detection oscillator (5/6) are both one point and the same point. Therefore, the following advantages are obtained: In the conventional point support by a plurality of anchors, stress was conventionally applied to the beam portion of the x-vibrator due to the influence of the deflection of the base supporting the anchor due to the supporting environment temperature or self-heating of the x-vibrator and external force. However, in the present invention, since the beam is supported at one point O as described above, the above-described stress is not applied to the beam. Therefore, discontinuous shift of resonance frequency and hysteresis due to disturbance or the like are reduced. The stationary point of the x-vibrator system and the detection vibrator system is point O, and is supported there, so that the leakage of vibration between the x-vibrator system and the detection vibrator system is reduced, so that the angular velocity detection is performed. 2. The accuracy is improved, and The first support beam (4) supported by the anchor at the point O includes a first flexible beam (41, 42/43, 44) which bends in the x and y directions. Since the connecting beam (1) is continuous and the connecting beam bends in the x direction and is continuous with the pair of x vibrators (2, 3), the pair of x vibrators (2, 3) becomes x Vibration easily in the direction.
Thus, since the excitation means (10A, 10B) drives the pair of x vibrators (2, 3) symmetrical with respect to the point O in the x direction in the opposite phase, the x driving vibration is almost a simple vibration. In addition, the vibration in the detection direction y is not applied to the detection vibrator, so that the angular velocity detection accuracy is improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (2) The detection transducers (5/6) are separated from each other in the x-direction from the y-axis and are symmetrically positioned with respect to a point O to form a pair. When an angular velocity about the z axis passing through the point O and perpendicular to the x and y axes is applied to the sensor, each x vibration of the pair of x vibrators (2, 3) becomes an elliptical vibration having a y vibration component, The connecting beam (1) generates torsional vibration around the z-axis. This torsional vibration propagates to the second support beam (7, 8), and the torsional vibration causes the pair of detection vibrators (5, 6) to move to the second flexible beam (71, 77 /
81, 87), they vibrate in opposite directions in the y direction, but since each of the detection transducers (5, 6) is separated from the y axis in the x direction, their y amplitude due to torsional vibration is reduced. , The detection oscillator (5,
6) The y vibration is large and the angular velocity detection accuracy is high. (3) The second support beams (7, 8) surround the detection vibrators (5, 6) and the second flexible beams (71, 77/81, 87) distributed on the x, y plane, and A stiffening beam (74,75 / 84,85) supported by an anchor (120) in continuation of the flexible beam. With this reinforcement beam (74,75 / 84,85),
Doubly supported via the second flexible beam (71,77 / 81,87) (balanced support)
Since the detection transducers (5, 6) are supported in the form,
(5, 6) is easy to make a simple vibration in the y direction, the vibration in the y direction is stable, and the angular velocity detection accuracy and stability are high. (4) The connecting beam (1) has a loop shape with the point O as the loop center. As a result, the inside of the loop (the space inside the loop of the connecting beam 1)
A detection vibration system (or x vibration system) is placed at
The sensor element can be compactly arranged, for example, by arranging a vibration system (detection vibration system). Also, the pair of x vibrators (2, 3) are driven to vibrate in opposite phases in the x direction by the excitation means (10A, 10B), that is, the pair of x vibrators (2, 3) are used as tuning forks. However, the first support beam (4) is bent in the x and y directions.
1,42 / 43,44), the connecting beam (1) is easy to bend in the y-direction, the loop of the connecting beam (1) is easy to expand and contract in the y-direction due to x-negative phase vibration, and the pair of x-vibration The phase (x) vibration of the child (2, 3) is easy. For example, when driven by the excitation means (10A, 10B),
When a driving external force is applied to the x vibrator (2, 3), the x vibrator (2, 3) tends to resonate in the opposite phase.

[0008] Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0009]

FIG. 1 shows a mechanical element according to an embodiment of the present invention. On the silicon substrate 100 on which the insulating layer is formed, floating body anchors 120 of polysilicon containing impurities for making it conductive (hereinafter referred to as conductive polysilicon), anchors of many drive electrodes 91 to 94, and many The anchors of the detection electrodes 111 and 112 are joined, and these anchors are connected to a connection electrode (not shown) by wiring formed on an insulating layer on the silicon substrate 100.

Using a lithographic semiconductor process, a center x-beam 46 of conductive polysilicon extending in the x-direction and floating from the silicon substrate 100 and continuous to the floating body anchor 120 and connected to the anchor 120
Is formed as a first loop 45 having a rectangular shape.

The first support beam 4 extends in the y direction from the intersection of the first loop 45 with the y axis passing through the center O of the anchor 120.
(Y arms 43, 44 and flexible rectangular loops 41,
42) extends and at the intersection of the loops 41 and 42 with the y-axis,
A rectangular second loop 1 (x parallel sides 11, 12, and y parallel sides 13, 14) is continuous with the first support beam 4. At the intersection of the y-parallel sides 13 and 14 with the x-axis, the first x-vibrators 21 and 22 and the second x-vibrators 31 and 3 continuous with them are provided.
2 is continuous. These elements are also used in the silicon substrate 10
It is floating from zero, is the same conductive polysilicon as the first loop 45, is supported by the anchor 120 at the center O, and is floating from the substrate 100.

The first x vibrators 21 and 22 are connected to a second loop.
The second x vibrators 31 and 32 are symmetrical in shape and symmetrical with respect to the y-axis with respect to the y-axis, and are symmetrical with respect to the y-axis. In position. These x vibrators 21, 22, 31 and 3
2 is also symmetric about the x-axis passing through the center O.

These x-vibrators 21, 22, 31 and 32
Have comb-shaped movable electrodes 23 and 33 distributed at equal pitches in the y-direction and projecting in the x-direction.
(91-94) and the drive detection electrodes 9A, 9B (101
104), there is a comb-shaped fixed electrode protruding into the space of the movable electrode 23, 33 in the y-direction distribution, which is distributed in the y-direction.

Drive electrodes 10A, 10B 91, 93 and 9
By applying a voltage higher than the potential of the x oscillator 2 (approximately the equipment ground level) to the x oscillator 2
Vibrates in the x direction. Due to the x-vibration, the capacitance between the x-vibrator 2 and the drive detection electrodes 9A and 9B 101 and 103 vibrates, and the x-vibrator 2 has a phase opposite to the capacitance vibration.
And the capacitance between 102 and 104 oscillates.

The x-vibrator 3 has a shape and a position symmetric with respect to the y-axis with respect to the x-vibrator 2, and a drive electrode for driving the x-vibrator 3 (a driving electrode which is symmetric with respect to the y-axis with 10A and 10B). ), A driving pulse having a phase opposite to that of the x-vibrator 2 is applied, so that the x-vibrator 3 vibrates in the x-direction in a phase opposite to that of the x-vibrator 2, and the x-vibrator 3 and the drive detection electrode (y 9A, 9B symmetrical about the axis)
The capacitance between the two oscillates. Drive pulses are applied to oscillators 2 and 3
With this resonance frequency, the x vibrators 2 and 3 generate resonance tuning fork vibration, and perform x vibration with high energy consumption efficiency.

Due to this x vibration, the second rectangular loop 1
Of the y-parallel sides 13 and 14 vibrate in the same manner as the x vibrators 2 and 3. As a result, the left and right ends of the x-parallel sides 11 and 12 (connecting points with the y-parallel sides) vibrate in the direction of approximately 45 degrees with respect to the x- and y-axes. Since the x-parallel sides 11 and 12 are symmetrical with respect to this, the vibrator does not vibrate in the x direction but vibrates only in the y direction. However, since the flexible rectangular loops 41 and 42 absorb the y vibration, the y vibration is slightly reduced.
4, the x-parallel side of the first loop 45 vibrates only slightly in the y-direction and does not vibrate in the x-direction.
The center x beam 46 is continuous with the first loop 45 at the midpoint of the y-parallel side of the first loop 45.
Even if the parallel sides vibrate in the y direction, the center x-beam 46 does not vibrate in the x direction, nor does it vibrate in the y direction. Therefore, no x vibration is applied to the anchor 120. With respect to the x excitation of the x oscillators 2 and 3, (the center O of) the anchor 120 is a stationary point, and eventually, the anchor 120 is connected to the x oscillators 2 and 3
Is supported at the stationary point.

The beam 7 for supporting the detection vibrator is located at the midpoint of the y-parallel side of the first loop 45 which does not vibrate in any of the x and y directions with respect to the x excitation of the x vibrators 2 and 3. y arm 7
3, the center of the y-direction is continuous, and U-shaped flexible beams 71, 72 are continuous at the y-direction end of the y-arm 73. Half pieces 51 and 5 of vibrator 5
2 is continuous. These halves 51 and 52 are continuous at the base (y-arm) 53 of the vibrator, and the first detecting vibrator 5 is symmetrical with respect to the x-axis. Further, with respect to the base 53, there are flexible beams 77, 78 and a y-arm 76 which are symmetrical with the flexible beams 71, 72 and the y-arm 73, and these are also connected to the halves 51, 52. A reinforcing y-arm 75 is continuous at a y-direction midpoint (intersection with the x-axis) of the y-arm 76, and a y-parallel side is continuous at an end of the y-arm 75 in the y-direction. The y-parallel side is continuous with the y-arm 74, and the y-arm 74 is continuous with the y-parallel side of the first loop 45.
These reinforcing members 75 and 74 also exist symmetrically with respect to the x-axis.

The second detecting vibrator 6 and the supporting beam 8
Are symmetrical with respect to the y-axis with respect to the first detecting transducer 5 and the supporting beam 7, and exist at symmetrical positions. The detecting transducers 5 and 6 and the supporting beams 7 and 8 are point-symmetric with respect to the center O and are symmetrically distributed with respect to both the x and y axes.

The above-described detecting vibrators 5, 6 and the beams 7, 8 supporting them are also made of conductive polysilicon and have substantially the same potential as the anchor 120. The half pieces 51, 52/61, and 62 of the detection vibrators 5 and 6 are roughly in the shape of a rectangular loop, and a bridge for a movable electrode parallel to the x-axis, which connects the opposing y-parallel sides, is in the y-direction. There is a pair of fixed detection electrodes 111 and 112 made of conductive polysilicon in each space between the bridge beams, supported by each anchor for the detection electrode on the substrate 100, and electrically connected thereto. (Continuous electrical connection). FIG. 2 shows A2 of FIG.
4 shows an enlarged cross section taken along line A2.

Referring again to FIG. 1, a pair of detection electrodes 11
Although the electrodes 1 and 112 are insulated, the detection electrodes at the corresponding positions between the pairs of the counter electrodes for detecting the y movement of the first detection transducer 5 are commonly connected. The same applies to each counter electrode for detecting the y movement of the second detection transducer 6.

When the x vibrators 2 and 3 are vibrating in the x direction in opposite phases, for example, when an angular velocity about an axis parallel to the z axis passing through the center O is applied, the vibrations of the x vibrators 2 and 3 are increased. , Y component, and a torsional vibration about the z-axis appears in the second loop 1, and a torsional vibration about the z-axis also appears in the first loop 45. This allows arm 7
3, 76/83, and 86 vibrate in the y direction, and the detecting vibrators 5 and 6 vibrate in the y direction.
The vibrations are out of phase.

FIG. 3 shows an electric circuit connected to the angular velocity sensor shown in FIG. The timing signal generator TSG
A drive pulse signal for driving the x vibrators 2 and 3 in the x direction in a reverse phase at a resonance frequency is generated, and drive circuits a1 to a4 and b1 to
In addition to b4, a synchronous signal for synchronous detection is applied to synchronous detection circuits e1 to e5.

FIG. 4 shows that the drive circuits a1 to a4 and b1 to b4 are driven by the drive electrodes (10A, 10A, 10B) in synchronization with the drive pulse signals.
B: 91 to 94). This allows
The x vibrators 2 and 3 perform tuning fork vibrations having the opposite phases in the x direction.

The x-vibration of the x-vibrator 2 causes the capacitance of the opposing (101 and 103) of the drive detection electrode (9A) to vibrate in the opposite phase with respect to the vibrator 2. Differential amplifier c
1 to c8 (c1) differentially amplify the capacitance signal generated by the preamplifier, which represents the oscillation of these capacitances,
The amplitude of the capacitance signal generated by one preamplifier is approximately 2
A differential signal is generated by canceling the noise, and given to differential amplifiers d1 to d4. One differential amplifier (d1) is supplied with differential signals of the two differential amplifiers (c1, c2) having mutually opposite phases, and the differential signals are converted to the differential amplifier (d1). To the synchronous detection circuits e1 to e4 (e1). Synchronous detection circuits e1 to e4 (e1) detect a differential signal provided by the differential amplifier (d1), that is, an x-vibration detection voltage representing x-vibration, in synchronization with a synchronous signal having the same phase as the drive pulse signal. A signal representing the phase shift of the x vibration with respect to the signal is generated and supplied to a feedback processing circuit FCR. The feedback processing circuit FCR supplies the phase shift signals for adjusting the phase shift signal levels provided by the synchronous detection circuits e1 to e4 (e1) to the set values and the drive circuits a1 to a4.
4, b1 to b4 (a1, b1), and the drive circuit receiving the shift shifts the phase of the output drive voltages V1 to V8 (V1, V2) with respect to the drive pulse signal in accordance with the phase shift signal. In a state where all the phase shift signal levels of the synchronous detection circuits e1 to e4 have become substantially set values, the x oscillator 2,
The resonance tuning fork vibration of No. 3 becomes stable.

When an angular velocity about the axis parallel to the z-axis passing through the center O is applied during the stable resonance tuning fork vibration, y-vibrations appear in the detection vibrators 5 and 6 in opposite phases, and the amplitude of the vibration is the angular velocity. Corresponding to the absolute value, the phase difference between the detection transducers 5 and 6 (± 180
The sign of (degree) corresponds to the direction of the angular velocity.

The capacitance of the pair of detection electrodes (111, 112) for detecting the y-vibration of the detection vibrators 5, 6 (5) vibrates in a relatively opposite phase due to the y-vibration. A preamplifier generates a capacitance signal to generate differential amplifiers c9 and c10.
(C9) substantially doubles the differential signal of both signals, that is, the amplitude of the capacitance signal generated by one preamplifier, generates a differential signal in which noise is canceled, and provides the differential signal to the differential amplifier d5.

The differential amplifier d5 includes two differential amplifiers c
9 and c10, the differential signals of opposite phase relationship to each other are given,
The differential amplifier d5 converts these differential signals into a synchronous detection circuit e.
Give 5 The synchronous detection circuit e5 detects a differential signal provided by the differential amplifier d5, that is, a y-vibration detection voltage representing y-vibration, in synchronization with a synchronous signal in phase with the drive pulse signal.
A signal representing the angular velocity is generated. The polarity (±) of the angular velocity signal indicates the direction of the applied angular velocity, and the absolute value of the signal level indicates the magnitude of the angular velocity.

As described above, detection of x vibration (drive feedback) and detection of y vibration (yaw rate) include noise caused by voltage pulses applied to the drive electrodes by the drive circuits a1 to a4 and b1 to b4. Since the relative position of the detection electrode with respect to the drive electrode is the same everywhere, and the differential amplifiers c1 to c8 and d1 to d5 calculate the difference between the signals of the detection electrodes at the symmetric positions, the differential with respect to noise due to x excitation is obtained. The output is only noise appearing at the rising and falling points of the drive pulse, as shown in the bottom row of FIG. 4, and is removed by the basic detection circuits e1 to e5. Thus, the S / N of the x vibration feedback signal output from the synchronous detection circuits e1 to e4 is high, and the S / N of the angular velocity signal output from the synchronous detection circuit e5 is high.

FIG. 5 schematically shows the outline of the vibration system of the angular velocity sensor shown in FIG. 1. Referring to FIG. 5, the characteristics of the angular velocity sensor shown in FIG. 1 will be described. The x vibrators 2 and 3 are vibrated in the x direction in opposite phases. This state is shown in FIG. x vibrator 2,3
When an angular velocity is applied to the detection vibrators 5 and 6, the x vibrators 2 and 3 vibrate in the x direction, and receive Coriolis force proportional to the angular velocity in the y direction perpendicular to the vibration direction x and the detection axis z of the angular velocity. Vibrate. Since the detection oscillators 5 and 6 are stopped, they do not receive Coriolis force.

When a Coriolis force is applied, the x oscillator 2,
3 vibrates in the y direction, and their displacement in the y direction is proportional to the angular velocity; y displacement = (angular velocity × vibrator velocity × vibrator mass) / y
The spring constant in the direction is y displacement, which is a constant. The vibrators 2, 3/5, and 6 have a vibration mode at the time of resonance in the detection direction y in which the x vibrators 2 and 3 have phases opposite to each other and the detection vibrators 5 and 6 also have phases opposite to each other. Coincides with the center of gravity O of the entire floating body of the angular velocity sensor. Thus, when the x vibrators 2 and 3 receive Coriolis force, the detection vibrators 5 and 6 vibrate in the y direction as shown in FIG. In addition, the resonance frequency of the x vibrators 2 and 3 and
The resonance frequencies of the detection vibrators 5 and 6 are set slightly higher than the resonance frequencies of the x vibrators 2 and 3 from the balance between sensitivity and correspondence.
From the relationship between the masses of the x oscillators 2 and 3, the masses of the detection oscillators 5 and 6, and the spring constants in the respective detection directions y, the x oscillators 2 and 3
Reference numeral 3 denotes a configuration that hardly displaces in the y direction. Instead, the detection oscillators 5 and 6 are displaced greatly. As described above, the accuracy (S / N ratio) of this sensor can be improved since the leakage (crosstalk) of the drive (x) and detection (y) vibrations is small in principle.

Also, this structure is different from the conventional structure in that it does not forcibly suppress vibration, so that it is resistant to the influence of stress and temperature change. In addition, since the fixed point of the drive and detection vibrations almost coincides with the center of gravity of the sensor, and when subjected to Coriolis force as described above, it does not involve any rotational movement as compared with the conventional case, so even if there is no support, there is no center of gravity. In the position the support point is stationary. Therefore, since the external vibration (when mounted on a vehicle or the like) hardly affects the driving vibration and the detection vibration of the sensor, the S / N ratio is improved as compared with the conventional type. In addition, since the above-described support is used, the influence of thermal expansion due to temperature or the like is small, and the temperature correction can be reduced. Therefore, the S / N ratio is improved as compared with the conventional type.

The angular velocity sensor shown in FIG.
At the center of mass of the loop 3, the loop 1, which is a spring portion, continuously floats and supports them, so that there is substantially no change in the spring effect due to the deformation of the vibrating mass (2, 3) itself. , 3
The x vibration of is close to a simple vibration. The overall size can be reduced without changing the length of the spring (1). Since a driving force of x excitation applied to the x vibrators 2 and 3 is applied to a connection point (one point) with the loop 1, a component such as a torsion is hardly generated in a mode of vibration, and the x vibration becomes a simple vibration.

Since the angular velocity sensor shown in FIG. 1 employs a bi-resonant x-vibration system, the amplitudes of the x-vibrators 2 and 3 are amplified and a large change can be obtained. As a result, driving can be performed with a small amount of energy, so that cost can be reduced. Since a large displacement output can be obtained, the S / N is improved.

Further, in the angular velocity sensor shown in FIG. 1, the fixed point of each of the bi-resonant vibration modes is the center of gravity O, and the x vibrators 2 and 3 are supported by the center of gravity O (single point). As a result, the leakage of the x vibration does not occur in principle, so that the amplification factor of the detected vibration y can be increased. Detection vibration y
Since unnecessary vibration is not induced in the angular velocity signal, the S / N of the angular velocity signal is improved. Unnecessary vibration is not induced in driving vibration, and driving can be performed with simple vibration. Therefore, S / N is improved.

In the angular velocity sensor shown in FIG. 1, each of the centers of gravity of the x vibration system and the y vibration system is one point O,
Since they are the same point, no stress load is generated in the spring portions (1, 4, 7, 8) due to the effect of thermal expansion due to temperature, and the temperature characteristics are improved. In particular, the reliability (stability) of detecting the angular velocity is high when the device is used in an environment with a large temperature change such as a vehicle.

Further, since the spring portions (1, 4, 7, 8) of the angular velocity sensor shown in FIG. 1 are all formed in a bent shape, a stress load is applied to the spring portions due to the influence of thermal expansion due to temperature. It does not occur and the temperature characteristics are improved. As compared with the same resonance frequency, the outer shape can be made smaller, so that the cost is lower.

Further, springs (41, 42) for stress relaxation are added to the spring for the x drive vibration. As a result, the nonlinearity of the x drive vibration is improved, and the x-drive vibration oscillates in a single vibration.
N is improved.

When the angular velocity is not applied, the detecting oscillators 5 and 6 are substantially stationary and the detecting vibration y does not resonate with the driving vibration x. / N is improved.

The y-detection displacement of the detection oscillators 5, 6 is designed to be larger than the detection displacement of the x-vibrators 2, 3 in the detection direction y (the mass of 5, 6 is smaller than that of 2, 3). ), The influence of the y detection vibration on the x drive vibration is relatively reduced, and the S / N of the angular velocity signal is improved. X of the center of mass (53, 63) of detection transducers 5, 6 with respect to fixed point O
By increasing the distance, the detection oscillators 5, 6
Can be increased in the y direction, so that the angular velocity detection signal S
/ N can be increased.

The detecting oscillator 5 of the angular velocity sensor shown in FIG.
6 are flexible beams 71, 7 having high spring property (flexibility) in the y direction.
2 and supported by frames (74, 75) close to a rigid body. Since the detection vibrators 5 and 6 vibrate not in the torsional rotation mode but in a parallel and opposite phase to each other, an ideal sine output is obtained when the detection vibration y is detected by the capacitance, and the angular velocity signal S / N is improved.

The angular velocity sensor shown in FIG. 1 can be manufactured on a silicon wafer by a semiconductor process using a lithography and can be manufactured by a conventional semiconductor process, so that it can be manufactured at low cost. The floating body (4, 1-3 / 5-8) is formed from a single plate and can be easily formed by a semiconductor process.
Can be produced at low cost.

FIG. 6 shows a modification of the angular velocity sensor shown in FIG. 1 which is different from that shown in FIG. In this modification, an additional loop 47 and a y-beam 48 are interposed between the floating body anchor 120 and the x-beam 46 shown in FIG.
Beam 46 is connected to anchor 120.

FIG. 7 schematically shows an outline of a vibration system of this modified example. In this modification, since the loop 47 is added, the propagation of the torsional vibration is effectively performed as in the embodiment of FIG. 1, and the blocking of the excitation vibration x is more effective than the embodiment of FIG. It is. That is, the effect of not transmitting the x vibration of the x vibrators 2 and 3 to the detection vibrators 5 and 6 and the substrate 100 is high.

[Brief description of the drawings]

FIG. 1 is a plan view of one embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line A2-A2 of FIG.

FIG. 3 is a block diagram showing an electric circuit for exciting the embodiment shown in FIG. 1 and obtaining an angular velocity signal.

FIG. 4 shows drive circuits a1 to a4 and b1 to b4 shown in FIG.
Is a time chart showing the voltage applied to the drive electrodes 91 to 94 for x excitation.

5A and 5B are plan views schematically showing a configuration outline of a vibration system of the angular velocity sensor shown in FIG. 1, wherein FIG. 5A shows a state where an angular velocity is not applied, and FIG. 5B shows a state where an angular velocity is applied. .

FIG. 6 is a plan view showing a changed part of the angular velocity sensor shown in FIG. 1;

FIG. 7 is a plan view schematically showing a configuration outline of a vibration system of the angular velocity sensor showing a change unit in FIG. 6;

[Explanation of symbols]

1: second loop 11 to 14: x, y parallel sides 2, 3: x vibrator 21, 22, 31, 3
2: x vibrator 4: first support beam 41, 42: flexible rectangular loop 43, 44: y arm 45: first loop 46: x beam 47: additional loop 48: y beams 5, 6: detecting oscillators 51, 52/61, 62: half pieces 7, 8: beams for supporting the detecting oscillators 9A, 9B, 91 to 94: drive detection electrodes 10A, 10B, 101 to 104: drive electrodes 100: substrate 120: floating body anchor

Claims (4)

[Claims] 1. A pair of x oscillators which are symmetrically positioned with respect to a point O on the x, y plane; distributed in the x, y plane, symmetric with respect to the point O, and provided with a pair of x oscillators. Continuous,
A connecting beam that flexes at least in the x-direction; a first support beam that is symmetrical about point O, including a first flexible beam that is continuous with the connecting beam and that flexes in the x, y directions between point O and the connecting beam. A second support beam symmetrical with respect to point O, including a second flexible beam which is continuous with the detector and deflects in the y direction between point O and at the point O; An angular velocity comprising: an anchor supporting the first support beam and the second support beam; excitation means for driving the pair of x-vibrators in opposite phases in the x-direction; and means for detecting y-direction vibration of the detection vibrator. Sensor. 2. The angular velocity sensor according to claim 1, wherein each of the detection vibrators is apart from each other in the x-direction from the y-axis and is symmetrical with respect to the point O to form a pair. 3. The second supporting beam includes a detection transducer distributed on an x, y plane and a reinforcing beam surrounding the second flexible beam and supported by the anchor continuously to the second flexible beam. The angular velocity sensor according to claim 1. 4. The angular velocity sensor according to claim 1, wherein the connecting beam has a loop shape with the point O as a loop center.