JP2000088580A - Silicon gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon gyro which allows the elastic leg span to be reduced, improves the sensitivity without needing a high driving voltage, and is made at a low cost. SOLUTION: The silicon gyro is formed from an Si wafer and has three elastic legs 2a, 2b, 2c separated by two grooves. A vibrator 1 supporting the elastic legs 2a, 2b, 2c has a base a part of which is fixed to a base 3. A vertical electrode 4 is disposed in parallel to the array plane of the elastic legs 2a, 2b, 2c and near the elastic legs 2a, 2b, 2c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon gyro for detecting a rotational angular velocity using a Coriolis force generated when an elastic leg of a vibrator rotates while vibrating, and in particular, does not require a high voltage. And a silicon gyro capable of improving sensitivity.

[0002]

2. Description of the Related Art In recent years, a vibration type silicon gyro used for an on-vehicle navigation system, an attitude control device for an unmanned vehicle, and a screen shake prevention device for a video camera has been separated by two grooves. A vibrator having three parallel elastic legs, driving means for generating vibrations in the elastic legs, and detecting means for detecting a vibration component in a direction of the vibration generated in the elastic legs when the vibrator rotates A silicon gyro consisting of

[0003]

As means for detecting a stable angular velocity in a three-tuning fork silicon gyro of electrostatic capacity detection and electrostatic force drive, an electrode for driving or detection is provided between elastic legs. However, it is difficult to form the dimension W between the elastic legs smaller than the thickness d of the silicon wafer as the substrate in the silicon gyro having such a configuration. This is because it is difficult to form a through-hole in a narrow gap with respect to the thickness d of the substrate, and when trying to reduce the width of the horizontal electrode between the legs, the mechanical strength of the horizontal electrode becomes small, and the etching process and the like are reduced. This is because the damage frequency increases.

However, the relationship between the dimension W between the elastic legs as the vibrator, the thickness d of the substrate, and the magnitude Q of the resonance is as follows.
As the dimension W between the elastic legs is smaller than the thickness d of the substrate, Q
The value increases. This is clear from the graph of FIG. That is, if the dimension W between the elastic legs can be reduced, the displacement amount of the elastic legs can be increased even at a low voltage, so that the vibration state is stabilized and the sensitivity is increased.

[0005] In general, the electrostatic drive requires a relatively high voltage (10 to 50 V) in order to obtain a driving force obtained by a piezoelectric element such as PZT. However,
Most small devices are designed to work with power supplies below 15V. Therefore, when a voltage of 15 V or more is required, a voltage source other than the device is required,
There are disadvantages such as an increase in cost, a reduction in size, an increase in noise induced from a power supply, and a decrease in sensitivity.

The present invention has been made in view of the above points, and can reduce the size between the elastic legs, improve the sensitivity without requiring a high driving voltage, and can reduce the cost. It is intended to provide a certain silicon gyro.

[0007]

According to a first aspect of the present invention, there is provided a silicon gyro formed by a silicon wafer and separated by two grooves.
A silicon gyro having a plurality of elastic legs, wherein a part of a base of a vibrator supporting the elastic legs is fixed to a base, and a vertical electrode which is parallel to an arrangement surface of the elastic legs and is close to the elastic legs is arranged. It is characterized by having been established.

According to a second aspect of the present invention, there is provided a silicon gyro according to the first aspect, wherein a groove width W between the elastic legs and a thickness d of the elastic legs are W / d =
It is characterized by having a relationship of 1 to 0.02.

According to a third aspect of the present invention, there is provided a silicon gyro according to the first or second aspect, wherein the vertical electrode is formed on a drive electrode corresponding to each of the elastic legs, the groove and the outside of the elastic leg. It is characterized by comprising Coriolis detection electrodes corresponding to the sides.

Further, the silicon gyro according to claim 4 is the silicon gyro according to claim 1 or 2, wherein the vertical electrodes correspond to the drive electrodes corresponding to the respective elastic legs, and correspond to the grooves. And a horizontal electrode perpendicular to the direction in which the elastic legs are arranged and adjacent to the elastic legs is disposed outside the elastic legs.

According to a fifth aspect of the present invention, there is provided a silicon gyro according to the first to fourth aspects, wherein a driving electrode for each of the elastic legs is composed of two electrodes, and A drive synchronization electrode for detecting the Coriolis force in the vertical direction is further formed between the electrodes.

Further, the silicon gyro according to claim 6 is the silicon gyro according to claim 5, wherein the two drive electrodes are mutually inconsistent with AC components having mutually opposite phase relationships. DC with polarity relationship
It is characterized by applying a component.

According to these silicon gyros, a high Q value (thousands to tens of thousands) can be obtained by omitting the horizontal electrodes conventionally provided between the elastic legs and narrowing the dimensions between the elastic legs. be able to.

In addition, the drive electrodes for each of the elastic legs are
With the configuration of the two electrodes, the AC component having the opposite phase relationship and the DC component having the opposite polarity relationship are provided.
The components can be applied to the respective electrodes, and the mutual effects induced by the detection circuit system can be offset, so that the detection sensitivity can be improved.

The horizontal detection of the Coriolis force is as follows:
The detection can be performed by detecting a change in the overlap ratio between the elastic leg and the Coriolis detection electrode. Further, if a horizontal electrode is provided outside the elastic leg, the accuracy can be further improved. Further, the detection of the vibrator in the vertical direction can be performed by the drive synchronization electrode.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a plan view showing a first embodiment of the present invention, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. 3 is a sectional view taken along line 3-3 of FIG.

The silicon gyro body according to the first embodiment of the present invention shown in FIGS. 1 to 3 includes a vibrator 1, a base 3 and a vertical electrode 4.

The vibrator 1 is made of silicon and includes a base portion 1a and three elastic legs 2a, 2b, 2c parallel to each other and separated by two grooves extending from the base portion 1a. In the present embodiment, the vibrator 1 is joined to a base 3 made of glass in the vicinity of an end of the base 1a by means such as anodic bonding, and a groove width W between the elastic legs 2a, 2b, 2c. And the thickness d of the elastic leg 2 is such that W / d = 1 to 0.02. When W / d is set to 1 or less, the Q value becomes 1000 or more as shown in FIG. 9, and it is impossible to reduce W / d to 0.02 or less from the viewpoint of processing. Specifically, when the thickness d of the silicon wafer is 300 μm, the groove width W is preferably about 30 to 150 μm.

The vertical electrode 4 of the present embodiment is any one of a drive electrode 4A, a drive synchronization electrode 4B, and a Coriolis detection electrode 4C, and is provided in a groove 3a recessed on the upper surface of the base 3. The elastic legs 2 are arranged in parallel with the arrangement surfaces of the legs 2a, 2b, and 2c and close to the elastic legs 2.

Specifically, as shown in FIGS. 1 and 3, two drive electrodes 4A are provided for the elastic legs 2a.
a, 4Ab, and a drive synchronization electrode 4Ba disposed between the drive electrodes 4Aa, 4Ab for obtaining a REF output for synchronous detection of the elastic leg 2a are formed as vertical electrodes. Similarly, for the elastic leg 2b, two drive electrodes 4Ac and 4Ad and a drive synchronization disposed between the two drive electrodes 4Ac and 4Ad for obtaining a REF output for synchronous detection of the elastic leg 2b. An electrode 4Bb is provided between the two drive electrodes 4Ae and 4Af for the elastic leg 2c and a drive synchronous electrode between the two drive electrodes 4Ae and 4Af for obtaining a REF output for synchronous detection of the elastic leg 2c. 4Bc is formed as a vertical electrode. Coriolis detection electrodes 4Cb and 4Cc are respectively provided in portions of the groove 3a corresponding to the portions between the elastic legs 2a and 2b and between the elastic legs 2b and 2c.
Are formed as vertical electrodes. Further, in the present embodiment, the Coriolis detection electrodes 4 are provided on the portions of the groove 3a corresponding to the outer sides of the elastic legs 2a and 2c, respectively.
Ca, 4Cd is formed. Note that the vertical electrode 4 in the present embodiment is made of chromium.

When the vibrator 1 vibrates, the vibrator 1
a, 2b, and 2c vibrate around the base 1a. The vibration of the elastic legs 2a, 2b, 2c
a, but the level is weak and the base 1
There is almost no vibration at the end of a. In the present invention,
The end of the base 1a is joined to the base 3 so as not to affect the vibration of the elastic legs 2a, 2b, 2c.

As described above, the elastic legs 2a, 2
By forming the gap between b and 2c narrow, the Q value representing the magnitude of resonance can be increased. The Q value represents an output with respect to the input energy (in this case, the vibration amplitude of the elastic leg). As shown in FIG. 9, the resonance amplitude increases as the value increases. This means that, for example, a voltage of 100 V is necessary for driving the silicon gyro when the Q value is low, but a voltage of 15 V or less is sufficient by increasing the Q value. is there.
In addition, the Q value of the three tuning fork silicon gyro becomes higher as the distance between the elastic legs becomes smaller when the thickness of the substrate is constant in both the horizontal and vertical directions.

Also in the present embodiment, the elastic legs 2a, 2
By forming the gap between b and 2c as narrow as 30 to 150 μm and forming the silicon wafer substrate with a thickness of 300 μm, low voltage driving can be achieved.

When the vibrator 1 configured as described above is driven, the vibrator 1 can vibrate freely in the vertical or horizontal direction. The vibrator 1 vibrates without being twisted, and the displacement of the vibrator 1 due to the Coriolis force generated in the direction perpendicular to the driving direction makes it possible to detect the component in the direction perpendicular to the driving direction. The arrow in FIG. 3 indicates the driving direction of the elastic legs 2a, 2b, 2c of the vibrator 1 at a certain moment, and the driving directions of the left and right two legs 2a, 2c and the center leg 2b are reversed. It is shown that.

For driving or detecting the angular velocity of the vibrator 1, if single crystal silicon having few lattice defects is used for the vibrator 1 of the present embodiment, there is no distortion inside the vibrator 1 and the thermal characteristics are low. It is excellent in that it can perform all driving and angular velocity detection of the vibrator 1 in a non-contact manner, and does not require any additional structure that affects the vibration of the vibrator 1, so that stable angular velocity can be detected. Becomes

In other words, silicon as the material of the vibrator 1 has a high purity and a single crystal material having no defect can be easily used, so that a high Q value can be obtained (thousands to tens of thousands).
Also, since there are very few lattice defects, there is no fatigue due to vibration, no plastic fracture occurs even when vibrated with large amplitude, and no distortion or internal stress occurs inside silicon,
A stable output can be obtained even when used for a long time in an environment with a temperature change.

Further, since the vibrator 1 of the silicon gyro according to the present embodiment has no foreign material adhered thereto, stable vibration can be obtained without being affected by other structures as the vibration of the vibrator 1. When a piezoelectric element or an electrode is formed on the vibrator 1, no gap is formed between the vibrator 1 and no distortion or stress is applied to the vibrator itself. Further, there is no distortion due to the difference in thermal expansion coefficient between different materials, and there is no influence of temperature change due to different materials. Further, since the thermal expansion coefficient of silicon itself is as small as about 2 ppm, the influence on the resonance frequency is smaller than that of the piezoelectric element. Further, when the self-excited oscillation circuit is adopted, the oscillation frequency changes following the expansion and contraction of the vibrator 1, and the resonance state can be always maintained.

Further, since the vibrator 1 is made of silicon, it is possible to produce a large amount of fine processing accuracy collectively by using photolithography technology. , And can be prevented from affecting the output signal.

FIG. 4 is a block diagram showing an embodiment of driving and detecting the silicon gyro.

The oscillation circuit 101 applies a frequency of 50 KHz and an amplitude of 5 V to the Coriolis detection electrodes 4Cb and 4Cd.
Are applied. Further, the phase inversion circuit 10
By 2, a carrier having a phase opposite to that of the oscillation circuit 101 is applied to the Coriolis detection electrodes 4Ca and 4Cc.

Each of the elastic legs 2a, 2b, 2c of the vibrator 1 and the Coriolis detection electrode 4C, which is the vertical electrode 4, are separated by a gap of 20 μm, and generate a capacitance.

These capacitances are used for the CV conversion circuit 103.
Is converted to a voltage value. After passing through a side band frequency of 2 KHz, which is a resonance frequency of the vibrator 1, and passing 2 KHz of induction noise due to electrostatic driving, the signal passes through an HPF 104 having a cutoff frequency of 10 KHz. ) Synchronous detection is performed at a frequency and phase synchronized with 101. This output is output to LPF 106
Thus, a change in the capacitance in the horizontal direction between the Coriolis detection electrode 4C and the three elastic legs 2a, 2b, 2c of the vibrator 1 is obtained.

Since the vibrator 1 is made of low-resistivity silicon, the impedance with respect to an alternating voltage formed by the capacitance between each of the legs 2a, 2b, 2c of the vibrator 1 and the drive electrode 4A. The components may be considered to be electrically conductive. That is, the capacitance change due to the three legs to the CV conversion circuit 103 is directly connected to the signal extraction unit 100, and the elastic legs 2a, 2b, 2c
Are added by the CV conversion circuit 103.

The drive synchronization electrodes 4Ba, 4Bb, 4B
In c, the drive synchronization electrodes 4Ba and 4Bc are short-circuited and connected to the phase inversion circuit 121, and the drive synchronization electrode 4Bb is connected to the oscillation circuit 120. The oscillation circuit 120
It oscillates at a frequency of 70 KHz and an amplitude of 5 V.

These drive synchronization electrodes 4Ba, 4Bb, 4
Since Bc and the three elastic legs 2a, 2b, 2c of the vibrator 1 are separated by a gap of 20 μm, a capacitance is generated between them. These capacitances are CV
The voltage is converted by the conversion circuit 103 into a voltage value.

HPF 109 (cut-off frequency 10 KH
After passing through z), the synchronous detection circuit 110 performs synchronous detection at a frequency and a phase synchronized with the oscillation circuit (unit) 120. By passing this output through the LPF 111, the drive synchronization electrode 4B and the three elastic legs 2a, 2b,
A change in capacitance in the vertical direction between 2c and 2c is obtained.

Further, the driving electrodes 4Ac and 4Ad are connected to an amplification and DC voltage superimposing circuit 118, and the driving electrodes 4Aa, 4Ab, 4Ae and 4Af are also connected to an amplification and DC voltage superimposing circuit 119.

A phase detection circuit 114 for comparing the oscillation phase of a voltage controlled oscillator (hereinafter referred to as VCO) with the oscillation phase of the oscillator, a loop filter 115, and the VC
The output of the PLL unit 113 is determined by the PLL unit 113 composed of O116 and the + 90 ° phase shift circuit 112.
Since the signal is amplified by the amplifying and DC voltage superimposing circuits 118 and 119 and the DC voltage is further superimposed thereon, electrostatic attraction acts between each elastic leg 2a, 2b, 2c of the vibrator 1 and each drive electrode 4A. . Then, the drive electrodes 4Aa, 4A
b, 4Ae, and 4Af, and drive electrodes 4Ac, 4A
To d, an alternating voltage whose phase has been inverted by the phase inverter 117 is applied.

The output of the amplification and DC voltage superposition circuit 119 and the input of the CV conversion circuit 103 (that is, the vibrator 1
In the vertical direction is + 90 ° phase shift circuit 112
Thus, the output of the CV conversion circuit 103 is always delayed by 90 °. That is, the configuration is such that the vertical vibration of the vibrator 1 is delayed by 90 °, and its phase is kept locked by the PLL unit 113. Therefore, the vibrator 1 continues to oscillate in the vertical resonance state (actual displacement is delayed by 90 ° with respect to the driving phase of the vibrator) at the resonance frequency unique to the vibrator.

For this reason, even if there is a temperature change from the outside and the dimensions of the vibrator 1 are minutely changed to cause a change in the resonance frequency inherent to the vibrator, the oscillator always oscillates in a resonance state in which the displacement amount becomes maximum. Continue. The output of the PLL unit 113 is a synchronization signal of the synchronization detection circuit 107. Therefore, in the horizontal direction capacitance change component of the vibrator 1, the PLL unit 1
13, only the component synchronized with the output of the LPF 10 is detected.
8, the desired output is obtained.
Since the phase is locked by 13, no phase shift occurs due to the synchronous detection circuit 107, and a stable output is obtained.

When an angular velocity is generated in the silicon gyro in the extension direction of the vibrator 1, Coriolis force acts on each of the elastic legs 2a, 2b, 2c of the vibrator 1 vibrating in the vertical direction.

Object m moving at velocity V (vector value)
The Coriolis force Fc when the angular velocity w (vector value) is applied is expressed as Fc = 2 m (Vxw) (x indicates a vector product).

For example, when the vibrator 1 is vibrating vertically and when an angular velocity acts around the extension direction of the vibrator 1, the vibrator 1 receives Coriolis force in the horizontal direction. The vibrator 1 receives a horizontal force due to the Coriolis force, and is displaced in the horizontal direction in synchronization with the vertical vibration.

This displacement is proportional to the applied angular velocity. Since the amount of displacement of the vibrator 1 in the horizontal direction is proportional to the change in capacitance with the Coriolis detection electrode 4C, the silicon gyro is detected by detecting the change in capacitance in the horizontal direction of the vibrator 1 synchronized with the vertical direction. The magnitude and direction (rotation direction) of the angular velocity applied to the image can be understood. However, in the silicon gyro of the present invention, a horizontal electrode for detecting a change in capacitance is provided between the elastic poles 2a, 2b, 2c so as to form a narrow space between the elastic legs 2a, 2b, 2c. Not.

Therefore, in the present embodiment, the Coriolis detection electrode 4C and the corresponding elastic legs 2a, 2b,
The displacement in the horizontal direction is detected based on the change in the area of the overlap with 2c.

Further, in this embodiment, the vertical drive synchronization electrode 4B and the drive electrode 4A are formed as separate electrodes. Therefore, the oscillation circuit 120, the phase inversion circuit 1
21, amplification and DC voltage superposition circuit 118, amplification and DC
There is no need to divide the voltage by arranging a voltage dividing resistor in each connection connected to the voltage superimposing circuit 119,
Since only the necessary voltage needs to be supplied, the power supply voltage can be effectively used. That is, the silicon gyro can be driven at a low voltage.

The displacement in the vertical direction can be detected by obtaining the REF output for synchronous detection from the drive synchronization electrode 4B.

FIG. 5 is a block diagram showing another embodiment of driving and detecting the silicon gyro. This embodiment is different from the first embodiment in that DC components having opposite polarities are applied to two drive electrodes 4A corresponding to one elastic leg 2.

That is, the drive electrodes 4Ab and 4Af are connected to the amplification and DC voltage superposition circuit 134, and the drive electrodes 4Aa and 4Ae are connected to the amplification and DC voltage superposition circuit 1
35. The drive electrode 4Ad is connected to the amplification and DC voltage superimposition circuit 132, and the drive electrode 4Ac is connected to the amplification and DC voltage superposition circuit 131.

A phase detection circuit 114 for comparing the oscillation phase of the VCO 116 with the oscillation phase of the vibrator, a loop filter 115, and a P
The LL unit 113 and the + 90 ° phase shift circuit 112 always provide a + 90 ° phase difference between the input and output of the PLL unit 113, that is, between the input from the + 90 ° phase shift circuit 112 and the output from the VCO 116. At that time, PL
The output of L section 113 is supplied to amplification and DC voltage superimposing circuit 13.
1,132,134,135 and further DC
Since the voltage is superimposed, each elastic leg 2a,
2b, 2c and drive electrodes 4Aa, 4Ab, 4Ac, 4A
An electrostatic attraction acts between d, 4Ae, and 4Af.

Amplifying and DC voltage superimposing circuits 132 and 13
The output of the CV conversion circuit 103 and the input of the CV conversion circuit 103 (that is, the vertical vibration of the vibrator) are configured such that the output of the CV conversion circuit is always delayed by 90 ° by the + 90 ° phase shift circuit 112. ing. That is, the configuration is such that the vertical vibration of the vibrator 1 is delayed by 90 °, and its phase is kept locked by the PLL unit 113. Therefore, the vibrator 1 has a resonance state in the vertical direction at the resonance frequency unique to the vibrator (the actual displacement is 9
Oscillation continues in a state of 0 ° delay).

For this reason, even when there is a temperature change from the outside and the dimensions of the vibrator 1 are minutely changed and the resonance frequency unique to the vibrator is changed, the oscillation always occurs in a resonance state in which the displacement becomes maximum. Continue. The output of the PLL unit 113 is a synchronization signal of the synchronization detection circuit 107. Therefore, in the vertical capacitance change component of the vibrator 1, the PLL unit 1
13, only the component synchronized with the output of the LPF 10 is detected.
8, the desired output is obtained.
Since the phase is locked by 13, no phase shift occurs due to the synchronous detection circuit 107, and a stable output is obtained.

As described above, in the second embodiment, the drive electrodes are divided into a plurality (in the second embodiment, two vertical electrodes for each elastic leg 2 are provided), and the AC electrodes having opposite polarities which are opposite to each other. By adding the component and the DC component, the degree of influence of the driving component on the CV conversion circuit 103 can be reduced. That is, for example, if the respective sums of the AC component and the DC component of the drive electrodes 4Aa and 4Ab in the elastic legs 2a are obtained, they are canceled each other.
The elastic legs 2b, 2 arranged at the center or right side in the figure
The same applies to the drive electrodes 4Ac, 4Ad, 4Ae, and 4Af of c.

Then, as described above, each of the elastic legs 2a, 2b,
The drive electrode 4A corresponding to 2c is divided into a plurality of parts, and an AC component having an opposite phase relationship and a DC component having an opposite polarity relationship are applied to each other, so that the drive electrode 4A is divided per unit area. An electrostatic force equivalent to driving with one electrode can be obtained with almost no loss of electrostatic force, and noise such as induction applied to the CV conversion circuit 103 can be minimized.

That is, the drive electrodes are divided into a plurality of parts, and an AC component having a mutually opposite phase relationship and a DC component having a mutually opposite polarity relationship are applied to each electrode, thereby canceling each other's influence and detecting. By minimizing the noise induced on the electrode side and changing the electrode arrangement even in the same device, it is possible to improve the detection sensitivity and obtain a high S / N ratio. Compared to the case where one drive electrode is used, the same electrostatic force can be applied at the same voltage without damaging the electrostatic force applied to the vibrator 1.

The driving of the vibrator 1 performs a function equivalent to that of a single electrode, and furthermore, the amplitude of the AC component that causes the induction noise is finely adjusted, so that the canceling effect can be obtained. Can be enhanced.

FIGS. 6 to 8 show a silicon gyro according to a second embodiment of the present invention, and FIG. 6 is a plan view showing the structure of the vibrator 1 according to the second embodiment. FIG.
6 is a sectional view taken along line 7-7 in FIG. 6, and FIG. 8 is a sectional view taken along line 8-8 in FIG.

The silicon gyro body of the second embodiment also includes a vibrator 1, a base 3, and a vertical electrode 4. The vibrator 1 is made of silicon and has a base 1
a and three elastic legs 2a, 2b, 2c parallel to each other and separated by two grooves extending from the base portion 1a.

More specifically, as shown in FIG. 6 and FIG. 8, two drive electrodes having the same magnitude and opposite polarity AC and DC components are applied to the elastic legs 2a. 4Aa, 4Ab and the two drive electrodes 4Aa, 4Ab for obtaining a REF output for synchronous detection of the elastic leg 2a.
The drive synchronization electrode 4Ba provided between Ab is formed as a vertical electrode. Similarly, for the elastic legs 2b, two drive electrodes 4Ac and 4Ad to which AC components and DC components of the same size and opposite polarities are applied, respectively,
A drive synchronization electrode 4Bb disposed between the drive electrodes 4Ac and 4Ad for obtaining a REF output for synchronous detection of the elastic leg 2b, and has the same size with respect to the elastic leg 2c. Two drive electrodes 4Ae and 4Af to which AC components and DC components of opposite polarities are applied, and a drive synchronization electrode 4Bc between both drive electrodes 4Ae and 4Af for obtaining a REF output for synchronous detection of the elastic leg 2c. It is formed as a vertical electrode.

In this embodiment, the groove 3
a between the elastic legs 2a and 2b and between the elastic legs 2b and 2c
In the portions corresponding to the spaces, the Coriolis detection electrodes 4C are respectively provided.
e, 4Cf are formed as vertical electrodes.
The horizontal electrodes 5a and 5b that are perpendicular to the direction in which the elastic legs 2 are arranged and are close to the elastic legs 2a and 2c are provided outside the elastic legs 2a and 2c. The configuration is different from the silicon gyro. The other configuration of the silicon gyro body is the same as that of the first embodiment.

The silicon gyro according to the present embodiment having the above-described configuration basically exhibits the same characteristics as the above-described silicon gyro, and can obtain the same effects. Furthermore, in the inspection process at the time of mass production, it is necessary to measure the resonance frequency in the horizontal direction by driving the vibrator 1 in the horizontal direction, but the inspection work at that time can be easily performed. .

[0063]

As described above, according to the silicon gyro according to the present invention, by reducing the size between the elastic legs, the sensitivity for detecting the Coriolis force can be improved without requiring a high driving voltage. It has effects such as being able to do.

[Brief description of the drawings]

FIG. 1 is a plan view of a silicon gyro according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the silicon gyro of FIG. 1 taken along line 2-2.

FIG. 3 is a sectional view taken along line 3-3 of the silicon gyro in FIG. 1;

FIG. 4 is a block diagram of one embodiment showing driving and detection of the silicon gyro of FIG. 1;

FIG. 5 is a block diagram of another embodiment showing driving and detection of the silicon gyro of FIG. 1;

FIG. 6 is a plan view of a silicon gyro according to a second embodiment of the present invention.

FIG. 7 is a sectional view taken along line 7-7 of the silicon gyro shown in FIG. 6;

8 is a sectional view taken along line 8-8 of the silicon gyro shown in FIG. 6;

FIG. 9 is a graph showing a relationship between a gap between elastic legs and a Q value of a vibrator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Oscillator 2 Elastic leg 3 Base 3a Groove 4 Vertical electrode 4A Drive electrode 4B Drive synchronization electrode 4C Coriolis detection electrode 5 Horizontal electrode 100 Signal extraction unit 101, 120 Oscillation circuit 102, 117, 121, 130, 133 Phase inversion circuit 103C −V conversion circuits 104, 109 HPFs 105, 107, 110 Synchronous detection circuits 106, 108, 111 LPF 112 + 90 ° phase shift 113 PLL unit 114 Phase detection circuit 115 Loop filter 116 VCO 118, 119, 131, 132, 134, 135 Amplification and DC voltage superposition circuit

Claims (6)

[Claims] 1. A silicon gyro formed of a silicon wafer and having three elastic legs separated by two grooves, wherein a part of a base of a vibrator supporting the elastic legs is fixed to a base. And a vertical electrode parallel to the surface of the elastic legs and adjacent to the elastic legs. 2. The silicon gyro according to claim 1, wherein a groove width W between the elastic legs and a thickness d of the elastic legs have a relationship of W / d = 1 to 0.02. . 3. The vertical electrode according to claim 1, wherein the vertical electrode comprises a drive electrode corresponding to each of the elastic legs and a Coriolis detection electrode corresponding to the groove and an outer side of the elastic leg. Silicon gyro. 4. The vertical electrode comprises a drive electrode corresponding to each of the elastic legs, and a Coriolis detection electrode corresponding to the groove. The silicon gyro according to claim 1 or 2, further comprising a horizontal electrode disposed near the elastic leg. 5. A driving electrode for each of the elastic legs is constituted by two electrodes, and a driving synchronization electrode for detecting a Coriolis force in a vertical direction is further formed between the two driving electrodes. The silicon gyro according to any one of claims 1 to 4, characterized in that: 6. The silicon gyro according to claim 5, wherein an AC component having an opposite phase relationship and a DC component having an opposite polarity relationship are applied to the two drive electrodes. .