JP2000136934A - Detection-signal processor for angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a detection-signal processor which reduces the change in the level of an angular-velocity detection output with respect to a change in a driving amplitude and a driving frequency by calculating an angular velocity value in which the ratio of an amplitude in a driving direction detected by a vibration detection means to an amplitude in a detecting direction is used as a parameter. SOLUTION: A signal processing circuit 15 computes an angular velocity value Ω in which the ratio VDCy/VDCx of an amplitude in a driving direction (x) detected by a vibration detection means to an amplitude in a detection direction (y) is used as a parameter. That is to say, a synchronous detection circuit 15b DC-converts a signal Vy (t) in a driving frequency component, an LPF 15d cuts off a high-frequency noises, and a DC signal VDCy is given to a division circuit 15e. On the other hand, a vibration displacement signal V2x (t) is given to a synchronous detection circuit 15a, and it is DC-converted so as to be given to the division circuit 15e as a DC signal V2DCx after a high-frequency noise is cut off by an LPF 15c. The division circuit computes the ratio VDCy/VDCx and an amplifier 15f converts the ratio VDCy/VDCx into the angular velocity Ω so as to be outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a vibrator is excited in an x direction, that is, vibrated, and an angular velocity .OMEGA. Vibration of the vibration type angular velocity sensor which detects vibration in the direction y (or z) orthogonal to the drive direction x and the angular velocity Ω, that is, the detection direction y (or z), induced by the Coriolis force F generated in the detection direction The present invention relates to a detection signal processing device that generates a signal representing an angular velocity Ω based on a signal that has detected.

[0002]

2. Description of the Related Art The above-mentioned vibration type angular velocity sensor uses a piezoelectric vibrator in which a vibrator is made of a piezoelectric material such as quartz and an excitation electrode and a vibration detection electrode are joined to the piezoelectric material. A conductive thin film floatingly supported on a silicon substrate via an anchor is used as a vibrator, and the vibrator is electrostatically driven by a comb electrode for excitation and a comb electrode for vibration detection, and vibration is detected by a change in capacitance. And a type that detects vibration using electromotive force or electromotive voltage due to electromagnetic coupling.

Here, a more detailed example of the electrostatic drive type, which is one of them, is that a typical one is a set of floating comb electrodes (one set on the left side and one set on the right side of the floating thin film). Two sets of fixed comb electrodes are provided (left fixed comb electrodes and right fixed comb electrodes which mesh with and are parallel to each set of floating comb electrodes in a non-contact manner). By alternately applying a voltage between the left floating comb electrode / left fixed comb electrode and between the right floating comb electrode / right fixed comb electrode, the floating thin film vibrates in the x direction. When the angular velocity of rotation about the z-axis is applied to the floating thin film,
When the Coriolis force is applied to the floating thin film, the floating thin film has 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 obtained (for example, Japanese Patent Application Laid-Open Nos. 5-248872, 7-218268, 8-152327, 9). -127148, JP-A-9-42973).

In detecting vibration of a vibrator, a displacement detection mode for converting a displacement of the vibrator (position of the vibrator) into an electric signal, and a speed for converting a speed (displacement speed) of the vibrator into an electric signal. There is a detection mode. When it is desired to eliminate the fluctuation of the input potential of the detection circuit by a signal output from the sensor, the displacement speed is determined by a current / voltage conversion circuit using an operational amplifier or a bipolar transistor as shown in FIG. As shown in FIG. 8B, a charge amplifier (integrator) using an operational amplifier generates an electric signal indicating displacement, that is, a detection signal. The detection signal is voltage,
In the case of electromotive force caused by a magnetic field that does not want current to flow, buffer amplifiers, differential amplifiers,
The displacement speed is detected by an FET or the like. Further, the displacement signal can be obtained by time-differentiating the displacement signal, and the displacement signal can be obtained by integrating the displacement speed signal.

[0005]

In a vibration type angular velocity sensor, when an angular velocity .OMEGA. Is applied to a vibrator, an amplitude oscillating at a substantially driving frequency in a y direction induced by a Coriolis force F is detected. Output as a voltage proportional to the amplitude. However, the amplitude in the y direction depends on the relationship between the driving frequency, the resonance frequency in the x direction and the resonance frequency in the y direction, and the amplitude amplification factor e in the y direction.
And the amplitude a in the x direction, and the voltage amplitude and phase rotation of the detection signal are determined by the characteristics of the circuit, especially the first stage amplifier. Therefore, when the above characteristics change due to a change in environmental temperature or the like, there is a problem that the output level for the same angular velocity fluctuates. Further, since the output is proportional to the drive amplitude a, the amplitude a in the drive direction x can be accurately determined. In addition, constant value control was required.

A first object of the present invention is to reduce the level fluctuation of the angular velocity detection output with respect to the fluctuation of the driving amplitude a and the driving frequency f which cause the above-mentioned fluctuation of the output. A second object is to reduce the output level fluctuation even with respect to the characteristic change.

[0007]

First, an arithmetic expression and a symbol are defined as follows: x (t) = a · sin (ωt) (1) vx (t) = a · ω · cos (ωt) ・ ・ ・ (2) ix (t) = b ・ vx (t) = ba ・ ω ・ cos (ωt) ・ ・ ・ (3) Vx (t) = c ・ ba ・ a ・ ω ・cos (ωt) ・ ・ ・ (4) VDCx = d ・ c ・ b ・ a ・ ω ・ ・ ・ ・ (5) F (t) = 2 ・ m ・ vx (t) ・ Ω ・ (6) ky ≒ m · ω ² ··· (7) y (t) = e · F (t) / ky = e · 2 · m · vx (t) · Ω / (m · ω ² ) = e · 2 · m · a · ω · cos (ωt) · Ω / (m · ω ² ) = 2 · e · a · cos (ωt) · Ω / ω (8) vy (t) = − 2 · e · a · sin (ωt) · Ω (9) iy (t) = − 2 · g · e · a · sin (ωt) · Ω (10) Vy (t) = − 2 · h · g · e · a · sin (ωt) · Ω (11) VDCy = −2 · i · h · g · e · a · Ω (12) VDCy / VDCx = −2 · i · h · g・ E ・ a ・ Ω / (d ・ c ・ b ・ a ・ ω ) = − 2 · i · h · g · e · Ω / (d · c · b · ω) (13) = j · e · Ω / ω (14a) j = −2 · i・ H ・ g / (d ・ c ・ b) Ω = (VDCy / VDCx) ・ ω / (j ・ e) (14b) V2x (t) = k ・ ba ・ sin (ωt) ・ ・・ (15) V2DCx = k ・ d ・ b ・ a (16) VDCy / V2DCx = −2 ・ i ・ h ・ g ・ e ・ Ω / (k ・ d ・ b) ・ ・ ・ (17) = j ′ · he · Ω / k (18a) j ′ = − 2 · ig / d · b Ω = (VDCy / V2DCx) · k / (j ′ · he) (18b) (−2 ・ h ・ g ・ e ・ a ・ Ω) ・ (c ・ b ・ a ・ ω) ・ ・ ・ (19) (c ・ b ・ a ・ ω) ²・ ・ ・ (20) ( −2 · h · g · a · Ω) / (c · b · a · ω) = − 2 · h · g · e · Ω / (c · b · ω) = (VDCy / V2DCx) · d / I (21) Ω = (VDCy / V2DCx) · k / (j ′ · he · e) = [(− 2 · h · g · e · a · Ω) / (c · ba · ω)] ・ (i / d) / (j ′ ・· E) ··· (22).

X (t): displacement of x vibration of vibrator vx (t): displacement speed of x vibration of vibrator ix (t): current value proportional to displacement speed vx (t) Vx (t): x Voltage representing the displacement speed of the vibration VDCx: DC voltage representing the displacement speed of the x-vibration F (t): Coriolis force Ω: Angular velocity around the z-axis applied to the transducer y (t): y-direction of the transducer due to Coriolis force Displacement vy (t): Displacement velocity in the y direction of the vibrator due to Coriolis force iy (t): Current value proportional to displacement velocity vy (t) Vy (t): Voltage representing displacement velocity of y vibration VDCy: DC voltage representing displacement speed V2x (t): voltage representing displacement of x vibration a: amplitude f: vibration frequency (= ω / (2π)) b: proportional coefficient c: proportional coefficient d: proportional coefficient m: vibrator Mass e: Amplitude amplification factor of oscillator in y direction g: Proportional coefficient h: Current-voltage conversion coefficient of y vibration sensor i: Proportional coefficient j: Proportional coefficient k: x vibration Sensor current-voltage conversion coefficient j ': proportional coefficient.

The vibrator is a sinusoidal vibration x in the x direction of the equation (1).
Assuming that (t) is satisfied, the displacement velocity vx (t) is given by equation (2). When a current ix (t) expressed by the equation (3), which is proportional to the displacement velocity vx (t), is generated by the x vibration sensor and the current ix (t) is converted into a voltage, the voltage Vx ( t) is obtained. When this voltage Vx (t) is converted into a DC voltage, a DC voltage VDCx represented by equation (5) is obtained.

When a constant angular velocity Ω having the z axis as a rotation axis is applied to the vibrator, a Coriolis force F (t) of equation (6) is applied to the vibrator. When the resonance frequency of the vibrator in the driving direction x and the resonance frequency of the angular velocity detection direction y are substantially equal to each other with a difference of about 1%, the spring constant ky in the y direction is expressed by the equation (7). Since the displacement y (t) in the y direction due to the Coriolis force F (t) is proportional to the Coriolis force F (t) and inversely proportional to ky, assuming that the amplitude amplification factor of the vibrator in the y direction is e, (8) It is expressed by an equation. The displacement velocity vy (t) in the y-direction is a differential value of the displacement y (t) in the y-direction and is expressed by equation (9).

(10) proportional to the displacement velocity vy (t) in the y direction,
When a current iy (t) shown in the equation is generated by the y vibration sensor and the current iy (t) is converted into a voltage, a voltage Vy (t) shown in the equation (11) is obtained. When this voltage Vy (t) is converted into a DC voltage, (12)
The DC voltage VDCy shown by the equation is obtained.

Next, when the ratio between VDCy and VDCx is obtained, equation (13) is obtained, and the amplitude a in the driving direction x disappears. This eliminates the need for a highly accurate amplitude control in the driving direction x, which was conventionally required. Since g and b, h and c, and i and d are equivalent signal conversion coefficients, the characteristic changes with respect to temperature and frequency are considered to be equivalent, and VDCy / VDCx is expressed as in equation (14a). j
Is a constant. VDCy / VDCx is proportional to e and Ω and inversely proportional to ω. From the equation (14a), the angular velocity Ω is obtained as shown in the equation (14b). The value of the angular velocity Ω is obtained in a form that is proportional to (VDCy / VDCx) and ω and inversely proportional to e.

The "speed" of the vibration in the driving direction x of the vibrator is detected by a vibration sensor, the "speed" of the vibration in the detection direction y is detected by a vibration sensor, and the angular velocity Ω is calculated based on both the detected values. In the embodiment, the displacement signals Vx (t) and Vy (t) expressed by the equations (4) and (11) are obtained from each vibration sensor.
From these signals, an electric circuit that generates a signal representing the angular velocity Ω by calculating the expressions (5), (12) and (14b) may be employed.

In a mode in which the "displacement" of the vibration in the driving direction x and the detection direction y of the vibrator is detected by the vibration sensor, and the angular velocity Ω is calculated based on both detected values,
Since the displacement signals x (t) and y (t) expressed by the equations (1) and (8) are obtained, these are differentiated to obtain the displacement signal Vx (t) expressed by the equations (4) and (11). ), Vy (t), and a signal representing the angular velocity Ω by calculating the equations (5), (12) and (14b) from these signals Vx (t) and Vy (t). May be employed as an electric circuit that generates

The "speed" of the vibration of the vibrator in the detection direction y
Is detected by the y vibration sensor, and the “displacement” of the vibration in the driving direction x is detected.
Is detected by the x-vibration sensor, the displacement signal (voltage) V2x (t) of the x-vibration of the vibrator can be expressed by Expression (15). When this is converted into the DC voltage V2DCx, the equation (16) is obtained. Then V
When the ratio between DCy and V2DCx is obtained, Expression (17) is obtained, and the angular velocity Ω can be calculated by Expression (18b). Since h and k are constants, if h / k is made constant with respect to fluctuations in temperature and the like, it depends only on e, and only the relationship between the resonance frequency in the driving direction x and the angular velocity detection direction y , The sensitivity variation will depend. This is because the above-mentioned VDCy / V2DCx is also used when the displacement is detected by detecting each vibration in the drive direction x and the detection direction y of the angular velocity by “displacement speed” detection and integrating the displacement speed detection signal in the drive direction x. The equation becomes equivalent to the equation (17) to be calculated, and the fluctuation of the sensitivity due to the fluctuation of the characteristic of the circuit to the environmental change can be minimized.

Further, the amplitude (-2 · h · g · e · a · Ω) of the detection signal Vy (t) in the detection direction y expressed by the equation (11) and the detection of the driving direction x expressed by the equation (4) are obtained. The product of the amplitudes (c, b, a, ω) of the signal Vx (t) is as shown in equation (19), and an electric signal proportional to this product is a detection signal in the drive direction x represented by equation (20). Divided by the electrical signal proportional to the square of the amplitude of
(VDCy / V2DCx) · d / i, VDCy / VDCx, VDC
Equation (21) equivalent to equations (13) and (17) for calculating y / V2DCx is obtained. From equation (21), (VDCy / V2DCx) = [(− 2 · h · g · e · a · Ω) / (c · b · a ·
ω)] · (i / d) By substituting this into equation (18b), equation (22) is obtained, and in equation (21), (−2 · h · g · e · a · Ω) / (c · b · a · ω) can be used to calculate the angular velocity Ω.

In particular, when detecting the displacement of the drive direction x by detecting the speed (displacement speed) of the vibration in the detection direction y, or detecting the displacement of the vibration in both directions and differentiating the detection signal in the drive direction x to obtain the speed. In the case of conversion, since the phases of the signals in both directions match or are shifted by 180 degrees, it is possible to use a multiplier and a low-pass filter in a circuit for converting to a DC voltage. (1) Therefore, the detection signal processing device of the angular velocity sensor according to the present invention is capable of controlling the vibration displacement or displacement velocity in the driving direction (x) of the vibration type angular velocity sensor and the driving direction when the angular velocity (Ω) acts on the sensor. Vibration detecting means (10a, 10b, 13 / 11a, 11) for detecting vibration displacement or displacement speed in the orthogonal detection direction (y)
b, 14); and the vibration detecting means (10a, 10b, 13 / 11a, 11b, 1
Means (15) for calculating an angular velocity value (Ω) having as a parameter a ratio (VDCy / VDCx) of the amplitude in the driving direction (x) detected in 4) and the amplitude in the detection direction (y). In addition, in order to facilitate understanding, symbols of corresponding elements or corresponding items in the embodiments shown in the drawings and described later are added for reference in parentheses.

As described above, the ratio of VDCy to V2DCx (VDCy / V
DCx), the ratio is proportional to e and .OMEGA. And inversely proportional to .OMEGA., So it becomes a parameter of the angular velocity .OMEGA. As expressed by, for example, (13), (17) or (21), and (14b) , (18b) or (22) can be used to calculate the angular velocity Ω. For example, looking at the equation (17), h and k are constants. If h / k is made to be constant with respect to fluctuations in temperature and the like, it depends only on e. The sensitivity variation depends only on the relationship of the resonance frequency in the direction y. Fluctuations in sensitivity due to fluctuations in circuit characteristics due to environmental changes can be minimized.

[0019]

(2) The means (15) for calculating the angular velocity value includes means (15g) for calculating the square of the amplitude in the drive direction (x), and the amplitude in the detection direction (y) in the detection signal. And driving direction
means (15h) for calculating the product of the amplitudes of (x), and means (15e) for calculating the ratio of the square of the amplitude to the product of the amplitudes (Equation 21) as the parameter. (3) The vibration detecting means (10a, 10b, 13 / 11a, 11b, 14)
The displacement speed is detected (FIGS. 3 to 7). (4) The vibration detecting means (10a, 10b, 13) detects displacement (FIG. 2). (5) The vibration detecting means (10a, 10b, 13 / 11a, 11b, 14)
Detects the displacement in the drive direction and the displacement speed in the detection direction (Fig. 2+
(Figure 3). (6) The means (15) for calculating the angular velocity value includes a driving direction
An integrating means (15i) for integrating the displacement speed of (x) to obtain an amplitude is included.

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

[0021]

FIG. 1 shows a first embodiment of the present invention. This embodiment is an electrostatic drive type angular velocity sensor that detects the angular velocity applied to the vibrator 8 around the z-axis. On the silicon substrate 1 on which the insulating layer is formed, floating body anchors 2a to 2 made of polysilicon containing conductive impurities (hereinafter referred to as conductive polysilicon) are provided.
d is bonded, and the wiring (formed by a dotted line) formed on the insulating layer on the silicon substrate 1 allows the semiconductor thin film made of conductive polysilicon to be made of the vibration frame 6, the vibrator 8, the fixed electrode 9a, 9b / 10a and 9b are connected to connection electrodes (not shown) on the substrate 1. The silicon substrate 1
A wiring having a conductivity (n) opposite to the conductivity type (p) of the polysilicon is formed on the silicon substrate 1 by pn junction, and the wiring, the floating body anchors 2a to 2d, and the anchor portions of the connection electrodes are formed. May be joined. Further, instead of the silicon plate, the substrate 1 can be made of a material that is stable in the micromachine manufacturing process temperature and is good for the environment, such as quartz glass, glass, ceramic, and high melting point metal.

A first set of floating support beams 3a to 3d extending in the y direction are continuous with the floating body anchors 2a to 2d, and parallel beams 4a and 4b are continuous with the support beams 3a to 3d. A rectangular ring-shaped vibrating frame 6, which is substantially parallel to the surface of the substrate 1, is continuous with the second set of floating support beams 5a to 5d extending in the y direction, which are continuous with the parallel beams 4a and 4b.

The side (y side or y side) of the vibrating frame 6 parallel to the y direction
A plurality of movable comb-shaped electrodes for x driving protruding from the parallel sides 6b and 6d in the left-right direction (x direction) at equal pitches in the y direction in a comb shape protrude. The pair of fixed electrodes 9a and 9b for x drive facing each other with the y side 6d interposed therebetween include:
has entered the interdental slot of the movable comb electrode on the y side 6d,
There is a comb-shaped fixed comb-teeth electrode for x drive, and there is a minute gap between the movable comb electrode for x drive and the fixed comb tooth electrode for x drive. x-drive fixed electrode 9a,
By alternately applying a voltage to 9b, the vibration frame 6 becomes x
Vibrates in the direction.

A pair of fixed electrodes 10a and 10b for detecting x vibration which face each other with another y side 6b interposed therebetween have:
has entered the interdental slot of the movable comb electrode on the y side 6b,
There are comb-shaped fixed comb-teeth electrodes for x-vibration detection, and there is a minute gap between the movable comb electrode for x-vibration detection and the fixed comb-teeth electrode for x-vibration detection. Vibration frame 6 is x
When it vibrates in the direction, the capacitance between the fixed electrodes 10a and 10b and the vibration frame 6 changes in height in opposite phases.

A third set of floating support beams 7a extending in the x direction
7d are connected to the y-side 6b of the rectangular ring-shaped vibrating frame 6,
6d, and the other ends of these support beams are connected to the y of the vibrator 8 in the inner space of the b-shaped ring of the vibrating frame 6.
The sides 8b and 8d are integrally connected. The y-sides 8b and 8d of the vibrator 8 are parallel to the third set of support beams 7a to 7d.
A movable electrode 8e for y displacement detection extending in the x direction is distributed in the y direction, and extends in the x direction from the y sides 8b and 8d. Within one pitch of the distribution of the movable electrodes 8e, there is a pair of fixed electrodes 11a and 11b for detecting y displacement, and each pair is distributed in the y direction.

As described above, the first set of floating support beams 3a to 3d,
Parallel beams 4a, 4b, second set of floating support beams 5a to 5d, vibrating frame 6, third set of floating support beams 7a to 7d, vibrator 8, and comb teeth of fixed electrodes 9a, 9b / 10a, 10b Is
It is separated from the surface of the substrate 1 in the z direction. That is, the substrate 1
, Facing each other with a gap. They are,
After the floating body anchor and the fixed electrode anchor are formed on the surface of the silicon substrate 1 by the micro-machining technology, they are formed integrally and continuously on the floating body anchor and the fixed electrode anchor. As described above, a support mode that is separated from the surface of the substrate 1 in the z direction and that can be displaced or bent in the x direction, the y direction, or the z direction with respect to the substrate 1 is referred to as “floating” or “movable” in this document.

The shape of the above-mentioned vibrating frame 6 is a ro-shaped ring, which is vertically and horizontally symmetrical with respect to the intersection of the two diagonal lines, and whose center of gravity is at the intersection. The vibration frame 6 has a third
The vibrator 8 which is integral and continuous through the set of support beams 7a to 7d is also
It is vertically and horizontally symmetric with respect to the intersection, and the center of gravity is at the intersection.

The first set of floating support beams 3 supporting the vibration frame 6
a to 3d and the second set of floating support beams 5a to 5d
Because they are floating from and extend in the y-direction,
Although it does not bend in the direction, it is easy to bend in the x direction.
Are less likely to vibrate in the y direction and more likely to vibrate in the x direction. Since the vibrator 8 is integral with the vibrating frame 6 and is supported by the vibrating frame 6 via the third set of floating support beams 7a to 7d extending in the x direction, when the vibrating frame 6 vibrates in the x direction. The vibrator 8 also vibrates in the x direction. The third set of floating support beams 7a to 7d does not bend in the x direction, but easily bends in the y direction, and the vibrator 8 hardly vibrates in the x direction with respect to the vibrating frame 6 and vibrates in the y direction. Easy to do. Thus, when an angular velocity about the z-axis is applied to the entire sensor (1 to 11), the vibrator 8 vibrates in the y direction, but the vibration frame 6 does not substantially vibrate in the y direction.

The vibration frame 6 (and the vibrator 8)
It is connected to the x drive circuit 12 via a to 2d and wiring (dotted line) on the substrate 1, where it is connected to the equipment ground (GND). The fixed electrodes 9a and 9b are connected to the x drive circuit 12 via wiring on the substrate 1. The x drive circuit 12 alternately applies a voltage for electrostatic attraction to the fixed electrodes 9a and 9b and repeats this at a resonance frequency in the x direction. The vibration frame 6 (and the vibrator 8) is pulled to the left in FIG. 1 when a voltage is applied to the fixed electrode 9a, is pulled to the right when a voltage is applied to the fixed electrode 9b, and moves to the left and right. Resonates and vibrates.

When the vibration frame 6 moves to the left, the capacitance between the movable comb-teeth electrode (x-side 6b) for detecting the x-vibration and the fixed electrode 10b for detecting the x-vibration decreases. The capacitance between the comb electrode (y side 6b) and the fixed electrode 10a for x vibration detection increases. The opposite is true when moving to the right. The movable comb electrode (y side 6b) is at the equipment earth potential (GND), while the fixed electrodes 10a and 10b are connected to the x vibration detection circuit 13. x vibration detection circuit 13
Generates an electric signal (displacement signal in the driving direction x) representing the position difference (differential amplification value) of the vibration frame 6 (equipment earth potential GND) with respect to the fixed electrodes 10a and 10b for x vibration detection, and It is given to the drive circuit 12. This electric signal is an AC signal (hereinafter referred to as an x vibration feedback signal) indicating a level change synchronized with the x vibration of the vibration frame 6. x drive circuit 1
2 generates a drive signal using the feedback signal, and applies a drive voltage synchronized with the drive signal to the fixed electrodes 9a and 9;
b.

When the vibrator 8 vibrates in the y direction, the vibrator 8
The capacitance between the movable electrode 8e and the fixed electrode 11a increases and decreases and vibrates, and the movable electrode 8e and the fixed electrode 11
The capacitance between b and fluctuates. y vibration detection circuit 1
Reference numeral 4 denotes an electric signal (displacement speed signal in the detection direction y) representing a difference (differential amplification value) of a displacement speed of the vibration frame 6 (equipment earth potential GND) with respect to the fixed electrodes 11a and 11b for y vibration detection. And this is given to the signal processing circuit 15.
When the x-vibration of the vibrator 8 (vibration frame 6) is constant, there is a fixed relationship between the angular velocity and the amplitude of the y-vibration of the vibrator 8 as shown in equations (6) to (11). There is. Signal processing circuit 15
Converts the displacement velocity signal in the detection direction y into a signal representing the angular velocity Ω (angular velocity signal) based on this relationship.

FIG. 2 shows the configuration of the x vibration detection circuit 13 and the x drive circuit 12, and FIG. Amplitude adjustment circuit 12a of x drive circuit 12 (FIG. 2)
The start signal generator included in the first embodiment generates a driving signal having substantially the same frequency as the resonance frequency of the vibration frame 6 + the vibrator 8 at the time of starting, and the phase shifter 12b generates the driving signal SDa whose phase is adjusted. The inverter 12d outputs the inverted signal S
Db. The output amplifiers 12e and 12h amplify the drive signals SDa and SDb and generate x excitation voltages VDa and VDb.
Is generated and applied to the fixed electrodes 9a and 9b for x excitation.

Since the drive signals SDa and SDb have opposite phases, the vibration frame 6 vibrates in the x direction, and the distance between the fixed electrodes 10a and 10b for x vibration detection and the vibration frame 6 in the x direction is opposite to each other. To change. Charge amplifiers 13a and 13b generate a voltage representing this displacement. Since the differential amplifier 13c differentially amplifies the displacement detection voltage of the opposite phase, the amplified output is the feedback signal V which cancels the common-mode noise contained in each displacement detection voltage of the charge amplifiers 13a and 13b.
2x (t), which is given to the amplitude adjustment circuit 12a of the x drive circuit 12. The amplitude adjustment circuit 12a is provided with a given field.
The amplitude of the feedback signal V2x (t) is monitored,
The feedback signal is amplified so as to be ef. The feedback signal whose level is thus standardized is supplied to the phase shifter 12b. The phase shifter 12b provides a drive signal SD for the feedback signal V2x (t) when the vibration frame 6 (including the vibrator 8) is vibrating x at its resonance frequency.
The feedback signal V2x (t) is delayed by a phase delay within ± 45 deg (°) with respect to the phase delay of a.
This is binarized into a rectangular wave having a duty of 50%, which is used as a drive signal SDa, a reverse phase signal of the drive signal SDa is generated by an inverter 12f, and this is used as a drive signal SDb, which is used as an output amplifier 12e. , 12h.

When the vibrator 8 is vibrating in the x direction, z
When an angular velocity around the axis is applied to the vibrator 8, the x vibration of the vibrator 8 becomes an elliptical vibration along the x, y plane. That is, a y component (y vibration) corresponding to the angular velocity appears. Thus, the vibrator 8 vibrates in the y direction with respect to the angular velocity detecting fixed electrodes 11a and 11b. The vibration detection circuit 14 (FIG. 3) includes current / voltage conversion amplifiers 14a and 14b using operational amplifiers.
A voltage representing the y displacement speed of the vibration frame 6 is generated. Since the differential amplifier 14c differentially amplifies the y-phase velocity voltage having the opposite phase, the amplified output is the y vibration velocity detection signal Vy (t ) Is given to the synchronous detection circuit 15b of the signal processing circuit 15. The synchronous detection circuit 15b converts the drive frequency component signal Vy (t) into a DC signal,
5d cuts off the high-frequency noise and supplies a DC signal VDcy representing the level of the y vibration velocity to the dividing circuit 15e. On the other hand, the x vibration displacement signal V2x (t) is supplied to the synchronous detection circuit 15a. The synchronous detection circuit 15a converts the drive frequency component signal V2x (t) into a DC signal, and the low-pass filter 15c blocks high-frequency noise, and supplies a DC signal V2DCx representing the level of x vibration displacement to the division circuit 15e. . Division circuit 15
e calculates VDcy / V2DCx, and the amplifier 15f converts the ratio VDcy / V2DCx into an angular velocity Ω according to the equation (18b), and outputs an electric signal representing the angular velocity Ω.

Second Embodiment FIG. 4 shows a configuration of a signal processing circuit 15 according to a second embodiment.
The mechanism of the sensor and the configuration of the x-vibration detection circuit 13 are as shown in FIGS. In the second embodiment, the speed signal Vy (t) of the y vibration and the displacement signal V2x (t) of the x vibration are given to the multiplier 15h, and the multiplier 15h receives (19)
The product of both is calculated according to the formula. The multiplier 15g calculates the square value of the displacement signal V2x (t) of the x vibration. Division circuit 15
e calculates (d / i) · (VDcy / V2DCx) according to equation (21), and the amplifier 15f calculates the ratio (d / i) · (VDcy / V2DCx)
Is converted into an angular velocity Ω according to equation (22), and an electrical signal representing the angular velocity Ω is output.

Third Embodiment The configuration of the x-vibration detection circuit 13 of the third embodiment is shown in FIG. 5, and the configuration of the signal processing circuit 15 is shown in FIG. The mechanism of the sensor is as shown in FIG. In the third embodiment, the vibration detection circuit 13 generates a voltage representing the x displacement speed of the vibration frame 6 by current / voltage conversion amplifiers 13d and 13e using operational amplifiers. Since the differential amplifier 13c differentially amplifies the opposite phase x displacement speed voltage, the amplified output is a voltage representing approximately twice the speed represented by one displacement speed voltage, and the respective displacement speed voltages of the amplifiers 13d and 13e. Is canceled out, and becomes a velocity signal Vx (t) of x vibration, which is supplied to the amplitude adjustment circuit 12a of the x drive circuit 12 and the integrator 15i of the signal processing circuit 15 in FIG.

The integrator 15i integrates the velocity signal Vx (t) of the x vibration to generate a displacement signal V2x (t) of the x vibration and supplies the displacement signal V2x (t) to the multipliers 15h and 15g. Similarly to the second embodiment, the multiplier 15h calculates the product of the two according to the equation (19). The multiplier 15g calculates the square value of the displacement signal V2x (t) of the x vibration. The dividing circuit 15e calculates (d / i) · (VDcy /
V2DCx), and the amplifier 15f calculates the ratio (d / i) · (VDc
y / V2DCx) is converted into an angular velocity Ω according to equation (22), and an electrical signal representing the angular velocity Ω is output.

Fourth Embodiment FIG. 7 shows a configuration of a signal processing circuit 15 according to a fourth embodiment.
The sensor mechanism and the configuration of the x-vibration detection circuit 13 are as shown in FIGS. In the fourth embodiment, the speed signal Vy (t) of the y vibration and the speed signal Vx (t) of the x vibration are given to the multiplier 15h, and the 90-degree phase shifter 15j is provided.
Converts the velocity signal Vx (t) of x vibration into a displacement signal equivalent to V2x (t) in the form of converting cos (ωt) into sin (ωt) in equation (4). Subsequent processing is the same as the processing of the signal processing circuit 15 of the third embodiment shown in FIG. 6, in which a value obtained by multiplying (VDcy / V2DCx) by a coefficient is calculated by a division circuit 15e, and the calculated value is calculated by an amplifier 15f. Convert to angular velocity signal.

Although the present invention has been described in the form of the driving direction x and the detecting direction y, the present invention can be similarly implemented in a mode in which the detecting direction is z. In this case, y and z in the above description are exchanged.

[Brief description of the drawings]

FIG. 1 is a drawing showing an outline of a first embodiment of the present invention, in which a sensor unit is a plan view and an electric circuit unit is a block diagram.

FIG. 2 is a block diagram showing a configuration of an x vibration detection circuit 13 and an x drive circuit 12 shown in FIG.

FIG. 3 is a block diagram showing a configuration of a y-vibration detection circuit 14 shown in FIG.

FIG. 4 is a block diagram illustrating a configuration of a signal processing circuit 15 according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an x vibration detection circuit 13 and an x drive circuit 12 to which a third embodiment of the present invention is applied.

FIG. 6 is a block diagram illustrating a configuration of a signal processing circuit 15 according to a third embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of a signal processing circuit 15 according to a fourth embodiment of the present invention.

FIG. 8 is an electric circuit diagram showing an example of a configuration of an amplifier conventionally used for detecting vibration, in which (a) is a current / voltage conversion amplifier that generates an electric signal indicating the speed of vibration;
(B) is a chart for generating an electric signal representing the displacement of vibration.
Shows the amplifier.

[Explanation of symbols]

1: substrate 2a to 2d: anchor 3a to 3d: support beam 4a, 4b: parallel beam 5a to 5d: support beam 6: vibrating frame 7a to 7d: support beam 8: vibrator 9a, 9b: fixed electrode for x excitation 10a, 10b: x
Fixed electrodes for vibration detection 11a, 11b: Fixed electrodes for y vibration detection 13: x vibration detection circuit 14: y vibration detection circuit 15: signal processing circuit (angular velocity calculation device)

Claims (2)

[Claims] 1. A vibration detecting means for detecting a vibration displacement or a displacement speed in a driving direction of a vibration type angular velocity sensor and a vibration displacement or a displacement speed in a detection direction orthogonal to the driving direction when an angular velocity acts on the sensor; And a means for calculating an angular velocity value having a parameter of a ratio between the amplitude in the driving direction detected by the vibration detecting means and the amplitude in the detection direction as a parameter. 2. The means for calculating the angular velocity value includes: means for calculating the square of the driving direction amplitude in the detection signal; means for calculating the product of the detection direction amplitude and the driving direction amplitude; 2. A detection signal processing device for an angular velocity sensor according to claim 1, further comprising means for calculating a ratio of a product of a square and an amplitude as the parameter.