JP2000009470A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the detection precision from lowering by a physical (electrical and mechanical) disturbance and to improve the angular velocity detection precision. SOLUTION: The angular velocity sensor is provided with a pair of parallel connection beams bb1 and bb2 being extended in x direction, a first drive frame 5 and a second drive frame 25 that are continuous to spring beams 1-4/21-24 with a high deflection property in x direction being continuous to them, are located between the pair of connection beams bb1 and bb2, and are aligned in x direction, a first drive body 11 that is located inside the first drive frame 5 and is continuous to beams 7-10 with a high deflection property in a y direction being continuous to it, a second drive body 31 that is located inside the second drive frame 25 and has a high deflection property in a y direction being continuous to it, excitation means 15, 16/35, and 36 for vibrating and driving at least one of the first and second drive frames 5 and 25 in x direction, first displacement detection means 13 and 14 for detecting the y vibration of the first vibration body 11, and second displacement detection means 33 and 34 for detecting the y vibration of the second vibration body 31.

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).

FIG. 4 of US Pat. No. 5,635,638 shows that a pair of vibrators are connected by a pair of semicircular beams, and each of the vibrators has high flexibility in the vibration direction x. Through the beam,
There is disclosed an angular velocity sensor in which the pair of vibrators are floated and supported by eight anchors.

[0004]

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.

In the angular velocity sensor disclosed in US Pat. No. 5,635,638, the vibration spring is not connected from the center of gravity of the vibrator. It is presumed to be balanced. In addition, nonlinear oscillation occurs. Therefore, it is presumed that S / N is poor because an unstable fluctuation of the detection output is generated due to the imbalance of the shift vibration of the resonance frequency. Since the driving vibrator and the detecting vibrator have the same mass, it is assumed that if the driving vibrator generates vibration in the detection direction due to a dimensional change during manufacturing, the S / N of the angular velocity signal decreases. Since the vibration of the detection vibrator is a torsional vibration supported at a plurality of points, the vibration leaks to the outside through the substrate, and the vibration component reflected outside returns to the substrate and is applied to the vibrator, so that the S / N of the angular velocity signal is reduced. It is presumed to decrease. Since the vibration drive signal is transmitted to the detection capacitor, it is assumed that the S / N of the angular velocity signal is low.

[0006] The present invention relates to physical (electrical and mechanical)
It is an object of the present invention to prevent a decrease in detection accuracy due to disturbance and to increase angular velocity detection accuracy.

[0007]

(1) An angular velocity sensor according to the present invention comprises a pair of parallel connecting beams (bb1, bb2) extending in the x direction and supported by a substrate (100); The first spring beam (1 to 4/21 to 24) having high flexibility in the x direction is continuous between the pair of connecting beams (bb1, bb2) and is arranged in the x direction.
A drive frame (5) and a second drive frame (25); a spring beam which is inside the first drive frame (5) and has high flexibility in the y-direction continuous therewith.
A first vibrating body (11) continuous to (7 to 10); continuous to a spring beam (27 to 30) inside the second drive frame (25) and having high flexibility in the y-direction continuous therewith; 2nd vibrating body (31); 1st drive frame
(5) Exciting means (15, 16/35, 36) for driving at least one of the second drive frame (25) in the x direction; a first means for detecting y vibration of the first vibrating body (11) Displacement detecting means (13, 14); and second displacement detecting means (33, 34) for detecting y-vibration of the second vibrating body (31). For easy 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, when the first drive frame (5) and the second drive frame (25) are vibrated in the x-direction in opposite phases by the excitation means (15, 16/35, 36), The first vibrating body (11) and the second vibrating body (31) also vibrate in opposite phases in the x direction, similarly to the first drive frame (5) and the second drive frame (25). When an angular velocity about the z-axis is applied, the first vibrating body (11) and the second vibrating body (3
1) is supported by a spring beam (7 to 10/27 to 30) having high flexibility in the y direction, so that the first vibrating body (11) and the second vibrating body
The vibration of (31) becomes an elliptical vibration, and also vibrates in the y direction. Since the x vibrations of the first vibrating body (11) and the second vibrating body (31) are relatively opposite in phase, the y vibration is also relatively opposite in phase. First
And the second displacement detecting means (13, 14/33, 34)
Detect vibration.

The first and second displacement detecting means (13, 14/33, 3
By performing the differential amplification of the vibration detection signal of 4), a vibration detection signal of a level approximately twice as large as the vibration detection signal of each displacement detecting means is obtained, and not only electrical noise is reduced, but also angular velocity is reduced. Signal components due to other mechanical external forces are also canceled. For example, when acceleration and deceleration in the y direction are applied, the movements of the first vibrating body (11) and the second vibrating body (31) are in the same direction, and the first and second displacement detecting means (13, 14 / The displacement detection signal levels of (33, 34) fluctuate in the same direction to the same extent, but if they are differentially amplified, the fluctuations of this signal level cancel out. Therefore, the S / N of the angular velocity signal does not decrease due to external force such as acceleration.

A spring beam having high flexibility in the x direction (1 to 4/21 to 2
4), the first drive frame (5) and the second drive frame (25) are supported by the connecting beams (bb1, bb2), are floatingly supported on the substrate (100), and have the first drive frame (25). 5) and the second drive frame (25) are less susceptible to temperature distortion;
In addition to stabilizing the x-vibration of (11, 31), the first and second vibrators (11, 31) can be moved through the spring beams (7 to 10/27 to 30) having high flexibility in the y-direction. Since the first and second vibrators (11, 31) are floated and supported, the first and second vibrators (11, 31) are less susceptible to temperature distortion, the y-vibration corresponding to the angular velocity is stabilized, and the reliability (stability) of the angular velocity signal is high.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (2) First vibrating body (11) and second vibrating body (11)
The vibrating body (31) is a frame-shaped body, and a first body is provided inside each of them.
And second displacement detecting means (13, 14/33, 34). (3) The pair of connecting beams (bb1, bb2) are symmetric about the x-axis and the y-axis passing through the intermediate point O between them, and the first and second drive frames (5, 25) are symmetric about the y-axis. Yes, the first and second vibrators (11, 31) are also symmetrical with respect to the y-axis. (4) Connected to a spring beam (1 to 4, 21 to 24) with high flexibility in the x direction supported by floating on a substrate. And the first drive frame arranged in the x direction
(5) and a second drive frame (25); a spring beam (61,6) having a high flexibility in the x direction connecting the first drive frame (5) and the second drive frame (25);
2); a first vibrator which is inside the first drive frame and which is continuous with the spring beam having high flexibility in the y direction which is continuous therewith; a y-direction which is inside the second drive frame and which is continuous therewith A second vibrating body continuous with a spring beam having high flexibility; an exciting means (15, 16/35, which vibrates and drives at least one of the first drive frame (5) and the second drive frame (25) in the x direction; 36); first displacement detecting means (13, 14) for detecting y vibration of the first vibrating body (11); and second displacement detecting means (13) for detecting y vibration of the second vibrating body (31). 33,3
4) an angular velocity sensor comprising;

In a preferred embodiment of the invention, the connecting beams (bb
The end of (1, bb2) is supported by a spring beam (b11, b16 / b21, b26) having one end supported by an anchor (a11, a16) and having high flexibility in the y-direction. Frame (5) and first vibrator (11)
A first set of vibration systems composed of a set of a second drive frame (25) and a second set of
A spring beam having a high flexibility in the x direction, one end of which is supported by an anchor (a12 to a15 / a22 to a25) in order to resonate the tuning fork with a second set of vibration systems composed of the vibrating body (31). b12-b15 / b22-b
25), and the arrangement of the angular velocity sensor elements with respect to the intermediate point O was all point symmetric.

According to this, a first set of vibration systems composed of an assembly of the first drive frame (5) and the first vibrator (11), and the second drive frame (25).
Although the second set of vibration systems consisting of the set of the second vibrator and the second vibrator (31) is anchored at multiple points via connecting beams (bb1, bb2), thermal expansion, internal stress, etc. The release does not break the symmetry about point O. Therefore, the reliability (stability) of the angular velocity signal is high.

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

[0015]

FIG. 1 shows a mechanical element of a first embodiment of the present invention. On the silicon substrate 100 on which the insulating layer is formed, floating body anchors a11 to a15 and a21 to a2 made of polysilicon containing conductive impurities (hereinafter referred to as conductive polysilicon) are provided.
5, anchors of drive electrodes 15, 16/35, 36, anchors of drive detection electrodes 17, 18/37, 38, anchors of angular velocity detection electrodes 13, 14/33, 34, and frequency adjustment electrodes 19, 20/39, 40. Anchors are connected, and these anchors are connected to connection electrodes (not shown) by wiring formed on the insulating layer on the silicon substrate 100.

By using a lithographic semiconductor process, spring beams b11, b16 / of conductive polysilicon floating in the x-direction, floating from the silicon substrate 100 and connected to the floating anchors a11 to a15, a21 to a25.
b21, b26, spring beams b12 to b15 extending in the y direction
/ B22 to / b25, and connecting beams bb1 and bb2 which are continuous with them and extend in the x direction. These connecting beams bb1 and bb2 have the same width and length, are parallel to each other, and are symmetric with respect to the x-axis passing through their intermediate point O.

Spring beams 1,2 / 21,22 and 3,4 / 23,24 extending in the y-direction and having high flexibility in the x-direction are continuous with the connecting beams bb1 and bb2, and the first spring beams are connected to these spring beams. The drive frame 5 and the second drive frame 25 are continuous, and the first and second drive frames 5 and 25 are provided inside the drive frames 5 and 25 via spring beams 7 to 10 and 27 to 30 which extend in the x direction and have high flexibility in the y direction. The vibrating body 11 and the second vibrating body 31 are continuous. These elements also float from the silicon substrate 100 and are conductive polysilicon.

The first and second drive frames 5 and 25, the first and second drive frames
Are symmetrical with respect to the y-axis passing through the sensor center O and are symmetrically positioned.
4, 7 to 10 and 21 to 24, 27 to 30 are also symmetrical with respect to the y-axis and located at symmetrical positions.

The first and second drive frames 5/25 each have a comb-shaped movable electrode 6 distributed at an equal pitch in the y direction and projecting in the x direction.
/ 26, and the drive electrodes 15, 16/35, and 36 made of conductive polysilicon connected to the drive electrode anchor also have comb-shaped fixed electrodes protruding into the space in the y-direction distribution of the movable electrode 6/26. There is a distribution in the y direction.

By applying a voltage higher than the potential of the drive frame 5 (25) (approximately the equipment ground level) to the drive electrodes 15 and 16 (35, 36) alternately, the drive frame 5 (25) moves in the x direction. Vibrates. In this embodiment, the drive frame 25
Is also driven in the x direction, but the x vibration has a phase opposite to that of the drive frame 5 in order to make a resonance tuning fork vibration.

The vibrating body 11 (31) vibrates x because it is connected to the drive frame 5 (25) by spring beams 7 to 10 (27 to 30) extending in the x direction. Drive frame 5 and vibrating body 11
And the second vibration system including the drive frame 25 and the vibrating body 31 are caused to vibrate in a resonant tuning fork manner, so that x vibration with high energy consumption efficiency is obtained.

When the drive frame 5 (25) vibrates in the x direction, the capacitance between the drive frame 5 and the drive detection electrodes 17 and 18 vibrates, and the drive frame 2 (25) has a phase opposite to the capacitance vibration.
5 and the drive detection electrodes 37 and 38 oscillate in capacitance.

The vibrating body 11/31 is also generally in the form of a frame, but a plurality of cross beams extending in the x direction exist at equal pitches in the y direction. Fixed detection electrodes 13, 14/3 of a pair of conductive polysilicon
3, 34, which are supported by the respective anchors for the detection electrodes on the substrate 100 and are electrically continuous therewith (in an electrical connection relationship).

Although the pair of detection electrodes 13 and 14 (33, 34) are insulated, the y-vibration (y
Each of the counter electrodes 13, 14 (33, 3) for detecting the
4) The detection electrodes at the corresponding positions between each pair are electric relays.
And the charge amplifiers 46 and 47 (56,
57).

When the vibrating bodies 11 and 31 are vibrating in a resonant tuning fork manner in the x direction and an angular velocity about the z-axis passing through the center O is applied, the vibrating bodies 11 and 31 are relatively out of phase having a y component. Elliptical vibration occurs, which causes the electrodes 13, 14/3
Capacitance vibration corresponding to y vibration is generated at 3, 34. Electrode 1
The capacitance oscillations of the electrodes 3 and 14 are relatively opposite in phase, and
The capacitance oscillations of 3, 34 are also relatively opposite in phase. Since the y-vibrations of the vibrators 11 and 31 are in opposite phases, the capacitance oscillations of the electrodes 13 and 33 are relatively opposite phases, and similarly, the capacitance oscillations of the electrodes 14 and 34 are relatively opposite phases. It is.

Comb-shaped movable electrodes 12, 32 distributed at equal pitches in the y direction and projecting in the x direction are also provided on the vibrators 11, 31.
The frequency adjusting electrodes 19, 20/39, and 40 made of conductive polysilicon connected to the fixed electrode anchor also have comb-shaped electrodes protruding into the space of the movable electrode 12/32 in the y-direction distribution. Distributed in the direction. These movable electrodes and frequency adjusting electrodes adjust the speed (spring force) of the x-vibration of the vibrating bodies 11 and 31, and adjust the resonance frequency (natural frequency) of the vibrating bodies 11 and 31 by the resonance of the drive frames 5 and 25. The frequency is lowered to several hundred Hz higher than the frequency. The drive frames 5, 25 excite both of them at the same frequency equivalent to the natural frequency by applying a drive voltage. In order to increase the angular velocity detection sensitivity, the resonance frequencies (natural frequencies) of the vibrators 11 and 31 are designed to be several hundred Hz higher than the resonance frequencies (natural frequencies) of the drive frames 5 and 25. By applying a DC voltage to the electrodes 19, 20/39, and 40 to adjust the level, the vibrating body 1
The resonance frequencies of 1, 31 are finely adjusted to values close to the design values.

The angular velocity sensors described above are connected to the angular velocity detection circuits 42 to 60, TSG, and FCR shown in FIG. The timing signal generator TSG is used to drive the driving frames 5 and 2
A drive signal for driving phase shifter 5 in the x direction at a resonance frequency is generated and supplied to drive circuits 41 and 51 and a synchronous signal for synchronous detection is supplied to synchronous detection circuits 45, 50 and 55.
FIG. 3 shows drive signals A and B, drive feedback signal and angular velocity signal, and x and y vibrations. The drive circuits 41 and 51 apply a drive voltage (pulse) to the drive electrodes 15, 16/35 and 36 in synchronization with the drive signals A and B. Thus, the vibrating body 11 together with the drive frame 5 and the vibrating body 31 together with the drive frame 25 vibrate in opposite phases in the x direction. Due to this vibration, the capacitances of the drive detection electrodes 17 and 18 vibrate in opposite phases, and the drive detection electrodes 37 and 38 also vibrate.
Vibrates in opposite phases. Charge vibrations 42, 43/52, 53 convert the vibration of the capacitance into voltage vibration (capacitance signal).

The differential amplifier 44 differentially amplifies the capacitance signals (opposite phases) of the amplifiers 42 and 43, makes the amplitude of the capacitance signal generated by one charge amplifier approximately double, and reduces noise. A canceled differential signal is generated and supplied to the synchronous detection circuit 45 and the feedback processing circuit FCR. Synchronous detection circuit 4
5 detects a differential signal provided by the differential amplifier 44, that is, an x-vibration detection voltage representing x-vibration, in synchronism with a synchronizing signal having the same phase as the drive signal, and detects a phase shift of x-vibration with respect to the drive pulse signal. A feedback signal is generated and supplied to a feedback processing circuit FCR.

The feedback processing circuit FCR provides the drive circuit 41 with a phase shift signal for adjusting the level of the phase shift signal provided by the synchronous detection circuit 45 to a set value. The phase of the output drive voltage with respect to the drive signal is shifted according to the signal. Synchronous detection circuit 4
In the state where the phase shift signal level of No. 5 substantially reaches the set value, the x vibration of the drive frame 5 becomes stable. The frequency adjustment circuit 59 applies a DC voltage that reduces the resonance frequency of the vibrating body 11 to a value that is several hundred Hz higher than the resonance frequency of the drive frame 5 to the frequency adjustment electrodes 19 and 20.

The driving and feedback circuits of the driving frame 25 and the vibrating body 31 are the same as those of the driving frame 5 and the vibrating body 11 described above. Then, the vibrating body 31 vibrates at a resonance tuning fork at substantially the same frequency as 11. When an angular velocity about the z-axis passing through the center O is applied during the stable resonance tuning fork vibration, Coriolis force is applied to the drive frames 5, 25 and the vibrators 11, 31, which include y vibration in addition to x vibration. Causes elliptical motion. However, the drive frames 5, 25 have high flexibility in the x direction but high rigidity in the y direction.
4, the y vibration is small. However, the vibrating members 11 and 31 have spring beams 7-1 having high flexibility in the y direction.
Since it is supported at 0, 27 to 30, it vibrates largely in the y direction. The y vibrations of the vibrating bodies 11 and 31 are relatively in opposite phases.

The capacitances of the pair of detecting electrodes 13 and 14 for detecting the y vibration of the vibrating body 11 oscillate in opposite phases, and the charge amplifiers 46 and 47 generate the capacitance signals representing the vibrations to generate differential signals. The amplifier 48 substantially doubles the amplitude of the differential signal of the two signals, that is, the amplitude of the capacitance signal generated by one charge amplifier, generates a differential signal in which noise is canceled, and supplies the differential signal to the differential amplifier 49. . The capacitance of the pair of detection electrodes 33 and 34 for detecting the y vibration of the vibrating body 31 oscillates in opposite phases, and the charge amplifiers 56 and 57 generate the capacitance signals indicating this, and the differential amplifier 58 The amplitude of the differential signal of the two signals, that is, the capacitance signal generated by one charge amplifier is approximately doubled to generate a differential signal in which noise is canceled, and the differential signal is given to the differential amplifier 49. The differential amplification signals of the differential amplifiers 48 and 58 are relatively out of phase. Therefore, the differential output of the differential amplifier 49 cancels out noise acting on each signal processing circuit of the first vibrating body 11 and the second vibrating body 31 at substantially the same level at the same time, and furthermore, acceleration, deceleration, vibration, etc. , The y-displacement component (also corresponding to noise) of the vibrating body due to the external force acting on the first and second vibrating bodies 11 and 31 simultaneously in the same direction is also cancelled.
This is a detection signal obtained by amplifying y vibration caused by angular velocity, and has high angular velocity detection sensitivity and high S / N.

The differential output, that is, the detection signal, is applied to a synchronous detection circuit 50, which detects the detection signal in synchronization with the synchronous signal having the same phase as the drive signal, and generates a signal representing the angular velocity. I do. 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.

Second Embodiment FIG. 4 shows mechanical elements of a second embodiment. In the second embodiment, in order to increase the linearity of the x vibration of the drive frames 5 and 25, the spring beams 1-4 and 21-24 are U-shaped spring beams having high flexibility in both the x and y directions. In addition, the U-shaped spring beams 61,
In addition, the drive frames 5 and 25 are connected by these. That is, the U-shaped spring beams 61 and 62 are continuous with the drive frames 5 and 25. Further, the x-vibrations of the vibrators 11 and 31 are also U-shaped spring beams in order to increase the linearity and make the vibrations independent. In the second embodiment, the driving vibration is close to a simple vibration, and the S / N of the angular velocity detection signal is improved. In the second embodiment, the first drive frame 5 and the second drive frame 25 are connected by U-shaped spring beams 61, 62, so that the resonant tuning fork vibration of the drive frames 5, 25 is possible. So the connection beams bb1 and bb
2 may be omitted, and the spring beams 1 to 4 and 21 to 24 may be floatingly supported on the substrate 100 by anchors. However, the connecting beams bb1 and bb2 release the processing distortion and the temperature distortion, and the drive frame 5,
Since it is effective to increase the linearity of the x vibration of 25,
It is preferable to use the connecting beams bb1 and bb2.

FIG. 5 shows a third embodiment of the present invention. In the third embodiment, a U-shaped spring beam 6 is provided as in the second embodiment.
At 1,62, the first drive frame 5 and the second drive frame 25 are connected,
The spring beams 1 to 4 and 21 to 24 are z-type spring beams having high flexibility in the x direction and low flexibility in the y direction, and the vibrators 11 and 3
The spring beams 7 to 10 and 27 to 30 supporting the first spring 1 are z-shaped spring beams having high flexibility in the y direction and low flexibility in the x direction. The difference from the second embodiment is that the spring beams 1-4, 21-24
Are hardly vibrated in the y direction, easily vibrated in the x direction, and the spring beams 7 to 10 and 27 to 30 are easily vibrated in the y direction.

FIG. 6 shows a fourth embodiment of the present invention. In the fourth embodiment, the increase in the internal stress of the drive frames 5, 25 and the vibrating bodies 11, 31 and the increase in the stress of the spring beams connected to each other due to the difference in the thermal expansion coefficient from the base substrate 100 are reduced. ,
The vibration characteristics are changed from non-linear to linear, a resonance tuning fork vibration is realized, and the S / N of the angular velocity signal is increased. The spring beam is a flat loop-shaped loop beam, and has high flexibility in a direction orthogonal to the substantially straight side of the loop and low flexibility in a direction parallel to the substantially straight side of the loop. . Vibrators 11, 31
Is supported on the drive frames 5 and 25 by the loop beams, so that it vibrates only in the direction of the detected vibration y and is hardly vibrated in other directions. Further, since the drive frames 5, 25 are also supported by loop beams, the drive frames 5, 25 and the vibrating body 1
Both 1 and 31 have a small increase in internal stress due to temperature and have linearity of vibration. The connecting beams are y parallel sides bb3, bb4
A substantially rectangular protection frame having four loop beams b
Anchor a1 via 11, b16, b21, b26
1, a16, a21, and a26. Thereby, the arrangement of the fixed electrode and the movable electrode is relatively symmetrically displaced by the dimensional change due to the thermal expansion of the substrate 100 or the protection frame (bb1 to bb4), and the capacitance change due to the temperature change is offset in the differential configuration. It has a configuration. The features of the angular velocity sensor of the present invention described above are listed below. (1) x-excitation of the drive frames 5 and 25 is performed by electrostatic force. (2) The drive frames 5 and 25 that are drive vibrators and the vibrators 11 and 31 that are detection vibrators are frame-shaped. 3) Spring beams (1 to 4, 21 to 24, bb)
1, bb2 / 61, 62), (4) the driving vibrator frames 5, 25 are formed outside so as to surround the detecting vibrator frames 11, 31, and (5) the vibrating bodies 11, 31 The y-displacement corresponding to the angular velocity is detected by the capacitance. (6) In order to oscillate the driving frequency and the detection frequency by dual resonance, the frequency on the detection side is several tens.
(7) The spring shape for vibrating the two driving vibrators 5 and 25 is π type (b1 in FIG. 1).
1, 2, 21), U-shaped (61, 62 in FIG. 4) or loop (FIG. 6) spring beams were used, and the driving vibration was inverted tuning fork vibration. The loop may be rectangular, circular or polygonal. (8) The plurality of driving oscillators 5, 25 are connected to the connecting beams (bb1 to bb4) by spring beams. (9) The driving oscillator 5 and 25 and the detecting vibrators 11 and 31 are connected by a plurality of spring beams 7 to 10 and 27 to 30. These spring beams have a specific shape of a flattened annular or rectangular spring. High flexibility only in the direction. (10) Many components are symmetrical with respect to their respective centers.
The combination of elements is symmetric about the center O. (12) The point of symmetry coincides with the center of gravity. (13) Each of the signal detection of the drive system and the signal detection of the detection system has a differential configuration.
The in-phase component of the detection signal is removed. (14) By including all of the above configurations, the leakage of electric noise during vibration due to electrostatic force is significantly reduced. (15) The S / N of the displacement signal is improved, and the S / N of the detected vibration displacement signal is improved.
N is improved, and the S / N of the angular velocity signal is improved. (16) The structure is surrounded by a polygonal frame (bb1 to bb4). This frame may be circular or elliptical. (16) The above frames (bb1 to bb4) or the connecting portions between the connecting beams bb1 and bb2 and the vibrators 5 and 25 are stress-relaxed to relieve stress during driving vibration. Beam 1
4, 21 to 24 are provided. Thereby, the linearity of the vibration and the simple vibration can be realized. (17) The above frame (bb1 to bb4)
The oscillators 5 and 2 are formed on the underlying silicon substrate 100 by loop spring beams (b11, b16, b21 and b26 in FIG. 6).
It was fixed at four or more locations symmetrically with respect to the center of gravity of No. 5. The loop may be circular or polygonal. Thus, the stress due to the thermal expansion difference of the vibrating body is reduced in the lower fixed substrate by the spring portion fixing the frame portion and the substrate, and the temperature characteristics are improved. The loop-shaped spring portion improves the linearity of the spring portion and improves the temperature characteristics of the spring itself. In addition, a spring structure that hardly induces a mode other than the predetermined vibration mode is used. (18) The spring constant of the above-mentioned spring beam is set sufficiently higher than the resonance frequency of the drive vibration and the detection vibration. Since the temperature characteristics have reproducibility and do not have hysteresis or discontinuous characteristics, the sensor has a low cost and a high S / N. (20) In a semiconductor process using lithography,
Since it can be constructed on a silicon wafer and can be manufactured by a conventional semiconductor process, it can be produced at low cost. 1 floating body
Formed from a single plate, it can be easily formed by a semiconductor process and can be produced at low cost.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing an outline of an angular velocity measuring circuit connected to the embodiment shown in FIG. 1;

FIG. 3 is a time chart showing voltages applied to drive electrodes 15, 16/25, and 26 for x excitation by drive circuits 41 and 42 shown in FIG. 2, wherein (a) and (b) are drive charts. The drive voltage applied to the electrodes is shown in FIG.
5, (d) shows the output signal of the synchronous detection circuit 50, (e) shows the output signal of the differential amplifier 44, and (f) shows the output signal of the differential amplifier 49.

FIG. 4 is a plan view of a second embodiment of the present invention.

FIG. 5 is a plan view of a third embodiment of the present invention.

FIG. 6 is a plan view of a fourth embodiment of the present invention.

[Explanation of symbols]

 a11 to a16, a21 to a26: anchors b11 to b16, b21 to b26: spring beams bb1 to bb4: connecting beams 1-4: spring beams 5: first drive frame 6: movable electrodes 7 to 10: spring beams 11: first 1 vibrator 12: movable electrode 13-20: fixed electrode 21-24: spring beam 25: second drive frame 26: movable electrode 27-30: spring beam 31: second vibrator 32: movable electrode 33-40: fixed Electrodes 61, 62: spring beams

Claims (4)

[Claims] 1. A pair of parallel connecting beams extending in the x direction and floatingly supported by a substrate; continuous with a highly flexible spring beam in the x direction which is continuous with the connecting beams and located between the pair of connecting beams. , A first drive frame and a second drive frame arranged in the x direction; a first vibrating body that is inside the first drive frame and is continuous with a spring beam having high flexibility in the y direction that is continuous with the first drive frame; a second drive A second vibrating body which is inside the frame and which is continuous with the spring beam having high flexibility in the y direction which is continuous with the second vibrating body; means for vibrating and driving at least one of the first drive frame and the second drive frame in the x direction; An angular velocity sensor comprising: first displacement detecting means for detecting y vibration of the first vibrating body; and second displacement detecting means for detecting y vibration of the second vibrating body. 2. The angular velocity sensor according to claim 1, wherein the first vibrating body and the second vibrating body are frame-shaped bodies, and the first and second displacement detecting means are located inside each of the first and second vibrating bodies. 3. The pair of connecting beams are symmetrical about an x-axis and a y-axis passing through an intermediate point O therebetween, the first and second drive frames are symmetrical about a y-axis, and the first and second vibrations are provided. 3. The angular velocity sensor according to claim 1, wherein the body is also symmetric with respect to the y-axis. 4. A first drive frame and a second drive frame arranged in the x direction and continuous with a spring beam having a high flexibility in the x direction supported by floating on a substrate; connecting the first drive frame and the second drive frame. Done x
A spring beam having high flexibility in the first direction; a first vibrating body which is inside the first drive frame and is continuous with a spring beam having high flexibility in the y direction which is continuous with the first drive frame; and which is inside the second drive frame. A second vibrating body that is continuous with a spring beam having high flexibility in the y direction that is continuous with the second vibrating body; means for vibrating and driving at least one of the first driving frame and the second driving frame in the x direction; y vibration of the first vibrating body An angular velocity sensor comprising: first displacement detecting means for detecting the vibration; and second displacement detecting means for detecting the y vibration of the second vibrating body.