WO2015146165A1

WO2015146165A1 - Angular velocity sensor, driving circuit and driving method for same, and angular velocity detection sensor device

Info

Publication number: WO2015146165A1
Application number: PCT/JP2015/001693
Authority: WO
Inventors: 一成澤田; 勇樹山中; 義博升井
Original assignee: 旭化成エレクトロニクス株式会社
Priority date: 2014-03-25
Filing date: 2015-03-25
Publication date: 2015-10-01

Abstract

　This angular velocity sensor driving circuit is an oscillation controller (5) for oscillating an angular velocity sensor unit (3) that has drive electrodes (D1, D2), detection electrodes (X1…), and an oscillator (3a), the circuit being provided with: a square wave generator (5b) for generating an oscillation start signal; a self-oscillation circuit (5a) for generating an excitation signal on the basis of a detection signal from the detection electrodes (X1…); a switching circuit (5c) for outputting an oscillation start signal to the drive electrodes (D1, D2) during an oscillation start interval in which oscillation by the oscillator (3a) starts, and outputting an excitation signal to the drive electrodes (D1, D2) during an angular velocity detection interval in which angular velocity is detected; a controller (5f) for controlling the switching circuit (5c) in such a way that the oscillation start interval and the angular velocity detection interval are repeated; and a sequencer (5e) for regulating the energy of the oscillation start signal that will be presented to the drive electrodes (D1, D2) during the next oscillation start interval, doing so on the basis of the amplitude, or the amount of fluctuation in amplitude, of the detection signal or the excitation signal during the angular velocity detection interval.

Description

Angular velocity sensor, driving circuit and driving method thereof, and angular velocity detecting sensor device

The present invention relates to an angular velocity sensor capable of performing intermittent and time-division oscillation in an oscillation operation, a driving circuit thereof, a driving method thereof, and an angular velocity detection sensor device.

Conventionally, there is an oscillating part that can be displaced inside, and by oscillating this oscillating part at a predetermined frequency, the angular velocity is detected by detecting the displacement generated by the Coriolis force generated in the oscillating part when the angular velocity is applied to the system There is known an angular velocity sensor for detecting the above.
As a method for detecting the displacement of the vibration part, there are a method for detecting a change in capacitance due to the displacement of the vibration part, a method for detecting a change in stress due to the displacement of the vibration part by a piezoelectric effect, and the like.
As a configuration of a conventional angular velocity sensor, a vibration unit supported to be displaceable by an angular velocity from the outside, a detection electrode that detects and outputs a change in stress due to displacement of the vibration unit by a piezoelectric effect, and a drive that vibrates the vibration unit The structure which has an electrode is mentioned.

Specifically, the following angular velocity sensors have been proposed.
Patent Document 1 discloses an angular velocity sensor including two drive electrodes D1 and D2 to which a drive signal for vibrating a vibration unit is input and four detection electrodes X1, X2, Y1, and Y2.
In the case of Z-Drive that vibrates the vibration part in the Z-axis direction, an in-phase sine wave Vdz is driven to the drive electrodes D1 and D2 to vibrate the vibration part in the Z-axis direction. Then, sin waves Vs_x1, Vs_x2, Vs_y1, and Vs_y2 whose phases are shifted by 270 ° with respect to the drive signal can be detected from the detection electrodes X1, X2, Y1, and Y2. With this detection signal, the following carrier wave and angular velocity can be detected.

The carrier wave Vs can be detected as an average value of the sin waves Vs_x1, Vs_x2, Vs_y1, and Vs_y2 detected from the detection electrodes X1, X2, Y1, and Y2, that is, “Vs = (Vs_x1 + Vs_x2 + Vs_y1 + Vs_y2) / 4”.
The angular velocity ωy of the Y axis can be detected as a value proportional to the orthogonal component of the difference between the sin waves Vs_x1 and Vs_x2 detected from the detection electrode X1 and the detection electrode X2, that is, “the orthogonal component of ωyω (Vs_x1−Vs_x2)”.
The X-axis angular velocity ωx can be detected as a value proportional to the orthogonal component of the difference between the sin waves Vs_y1 and Vs_y2 detected from the detection electrodes Y1 and Y2, that is, “the orthogonal component of ωx∝ (Vs_y1−Vs_y2)”.

In the case of X-Drive that vibrates the vibration part in the X-axis direction, the oscillating control part output signals Vdrx and -Vdrx of sine waves having opposite phases are driven to the drive electrodes D1 and D2 to vibrate the vibration part in the X-axis direction. . In the following description, signals having opposite phases, voltages, and the like may be represented by adding a minus sign (−) to the same sign. For example, in the above example, the sine wave oscillation control unit output signal Vdrx and the sine wave oscillation control unit output signal −Vdrx are signals that are 180 ° out of phase with each other. From the detection electrodes Y1, Y2, it is possible to detect the sin wave oscillation control unit output signals Vsx_X1, Vsx_X2, Vsx_Y1, Vsx_Y2 shifted by 270 ° with respect to the drive signal. With this detection signal, the following carrier wave and angular velocity can be detected.

The carrier wave Vsx can be detected as ½ of the difference between the sin waves Vsx_X1 and Vsx_X2 detected from the detection electrodes X1 and X2, that is, “Vsx = (Vsx_X1−Vsx_X2) / 2”.
The Z-axis angular velocity ωz can be detected as a value proportional to the orthogonal component of the difference between the sin waves Vsx_Y1 and Vsx_Y2 detected from the detection electrodes Y1 and Y2, that is, “the orthogonal component of ωz∝ (Vsx_Y1−Vsx_Y2)”.
As described above, a method is known in which the angular velocities around the angular axes are detected in a time-division manner by sequentially switching the angular velocities around the plurality of axes and the excitation direction, which is the direction in which the vibration unit vibrates.

Utility Model Registration No. 3159045 JP 2011-38955 A JP 2011-99818 A Utility Model Registration No. 3159045 JP 2011-99818 A

Patent Documents 1 to 3 disclose a technique for detecting angular velocity by changing the vibration direction of the vibration unit in a time-sharing manner. However, in the time-sharing operation, control or adjustment for stably vibrating the vibration unit. Is insufficient.
An object of the present invention is to provide an angular velocity sensor, a driving circuit thereof, a driving method thereof, and an angular velocity detecting sensor device capable of realizing a stable oscillation in which a vibration section stably vibrates in a time division operation.

In order to achieve the above object, an angular velocity sensor drive circuit according to an aspect of the present invention is an angular velocity sensor drive circuit that vibrates a sensor unit having a drive electrode, a detection electrode, and a vibration unit, and generates a vibration start signal. A vibration start signal generation circuit, an excitation circuit that generates an excitation signal based on a detection signal from the detection electrode, and the vibration start signal that is output to the drive electrode in a vibration start section in which vibration of the vibration unit starts. An angular velocity detection section for detecting angular velocity, an output section for outputting the excitation signal to the drive electrode, a control circuit for controlling the output section so that the vibration start section and the angular velocity detection section are repeated, and the angular velocity Based on the amplitude of the detection signal or the excitation signal in the detection section or the fluctuation amount of the amplitude, the vibration start signal applied to the drive electrode during the next vibration start section Characterized in that it comprises a an adjustment unit that adjusts the Energy.

In order to achieve the above object, an angular velocity sensor according to an aspect of the present invention includes the angular velocity sensor drive circuit according to the above aspect, and a sensor unit including a drive electrode, a detection electrode, and a vibration unit. Features.

In order to achieve the above object, the angular velocity sensor driving method according to one aspect of the present invention provides a vibration start signal in a vibration start section in which vibration of the vibration portion of the angular velocity sensor portion is started. Outputting to the drive electrode an excitation signal generated based on a detection signal from the detection electrode of the angular velocity sensor unit, and detecting the angular velocity detection interval Changing the amplitude or time of the vibration start signal to be output to the drive electrode in the next vibration start section based on the amplitude of the signal or the excitation signal or the fluctuation amount of the amplitude. To do.

In order to achieve the above object, an angular velocity sensor drive circuit according to another aspect of the present invention is an angular velocity sensor drive circuit that drives a weight portion having a drive electrode, and vibrates the weight portion in a first axis direction. A first drive signal, a second drive signal that vibrates the weight portion in the second axis direction, and a first static signal that stabilizes the vibration of the weight portion in the first axis direction are generated and output to the drive electrode. And a signal generation circuit that outputs the first drive signal from the signal generation circuit to the drive electrode in a section from detection of the angular velocity in the second axis direction to detection of the angular velocity in the first axis direction. An oscillation section is set, a first free section for freely vibrating the weight portion is set after the first oscillation section, and the first static signal is driven by the signal generation circuit after the first free section. First oscillation stop zone output to the electrode Set, characterized in that it and a control circuit for the second driving signal to set the second oscillation interval to be output to the drive electrodes from the signal generating circuit immediately after the first oscillation stop period.

In order to achieve the above object, an angular velocity detection sensor device according to an aspect of the present invention includes an angular velocity sensor drive circuit according to an aspect of the present invention, and a drive signal supplied by the angular velocity sensor drive circuit. An angular velocity for detecting an angular velocity from the detection signal output from the detection electrode, comprising a drive electrode, the weight portion that vibrates by the drive signal, and a detection electrode that outputs a detection signal output by the vibration of the weight portion. A detection circuit.

In order to achieve the above object, a driving method of an angular velocity sensor according to another aspect of the present invention is an angular velocity sensor driving method for driving an angular velocity sensor having a weight portion provided with a drive electrode. A first drive signal is output to the drive electrode in a first oscillation section that vibrates in one axial direction, and a first free section after the first oscillation section supplies a constant voltage to the drive electrode or the drive electrode In a floating state, and in a first oscillation stop section after the first free section, a first stabilization signal for stabilizing the vibration of the weight portion in the first axis direction is output to the drive electrode, and the first A second drive signal for vibrating the weight portion in the second axis direction is output to the drive electrode in a second oscillation section immediately after one oscillation stop section.

According to each aspect of the present invention, it is possible to stably vibrate the vibration part in the time-sharing operation and to realize stable oscillation.

It is a figure which shows an example of the frequency characteristic and envelope characteristic of an angular velocity sensor by an external drive. 1 is a circuit block diagram showing a schematic configuration of an angular velocity sensor 1 according to a first embodiment of the present invention. It is a figure which shows the connection state of the oscillation control part 5 in the oscillation start area at the time of the oscillation control part 5 with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped as Z-Drive. It is a figure which shows the connection state of the oscillation control part 5 in the stable oscillation area at the time of the oscillation control part 5 with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped as Z-Drive. It is a figure which shows the connection state of the oscillation control part 5 in the oscillation start area at the time of the oscillation control part 5 with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped as X-Drive. It is a figure which shows the connection state of the oscillation control part 5 in the stable oscillation area at the time of the oscillation control part 5 with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped as X-Drive. It is an image figure of the time division operation | movement in the angular velocity sensor 1 by 1st Embodiment of this invention. It is a figure explaining the angular velocity sensor 1 by 1st Embodiment of this invention, Comprising: It is a figure which shows the information obtained from the monitor part 1a and the monitor part 1b. It is a figure explaining the adjustment method of the oscillation amplitude of the rectangular wave drive signal which the rectangular wave generator 5b with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped outputs. It is a figure explaining the angular velocity sensor 1 by 1st Embodiment of this invention, Comprising: It is a figure which shows the example which prevents that a beat arises in the carrier wave Vs. It is a figure explaining the angular velocity sensor 1 by 1st Embodiment of this invention, Comprising: It is a figure which shows the other example which prevents that a beat arises in the carrier wave Vs. It is a figure which shows typically the oscillation amplitude characteristic of the carrier wave Vs at the time of the continuous oscillation of the angular velocity sensor 1 by 1st Embodiment of this invention. It is a figure which shows typically an example of the oscillation amplitude adjustment of the carrier wave Vs when the loop gain of the oscillation control part 5 with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped is larger than one. It is a figure which shows typically an example of the oscillation amplitude adjustment of the carrier wave Vs when the loop gain of the oscillation control part 5 with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped is smaller than 1. FIG. It is a figure explaining the procedure of amplitude adjustment of the carrier wave Vs of the angular velocity sensor 1 by 1st Embodiment of this invention, Comprising: It is a flowchart which shows an example of the flow of the adjustment procedure of a silicon device. It is a figure explaining the procedure of amplitude adjustment of the carrier wave Vs of the angular velocity sensor 1 by 1st Embodiment of this invention, Comprising: It is a flowchart which shows an example of the flow of a process of adjustment of a sensor module, and oscillation frequency control. It is a figure explaining the procedure of amplitude adjustment of the carrier wave Vs of the angular velocity sensor 1 by 1st Embodiment of this invention, Comprising: Another example of the process flow of the oscillation amplitude control of a sensor module and the oscillation control at the time of normal operation is shown It is a flowchart. It is a figure which shows the circuit structure and frequency characteristic of the phase shifter 6c with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped. It is a circuit block which shows an example of schematic structure of the rectangular wave generator 5b with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped. It is a figure explaining the angular velocity sensor 1 by 1st Embodiment of this invention, Comprising: It is a figure which shows an example of the operation | movement timing chart of the rectangular wave generator 5b in the oscillation start area T1 in Z-Drive. It is a figure explaining the angular velocity sensor 1 by 1st Embodiment of this invention, Comprising: It is a figure which shows an example of the operation | movement timing chart of the rectangular wave generator 5b in the oscillation start area T1 in X-Drive. It is a circuit block diagram which shows an example of schematic structure of the driver 6e with which the angular velocity sensor 1 by 1st Embodiment of this invention was equipped, and the switching circuit 5c. FIG. 2 is a diagram for explaining an angular velocity sensor 1 according to a first embodiment of the present invention, showing a schematic configuration of a connection state of a driver 6e, a rectangular wave generator 5b, and a switching circuit 5c in an oscillation start section T1 in Z-Drive. It is. FIG. 2 is a diagram for explaining an angular velocity sensor 1 according to a first embodiment of the present invention, and showing a schematic configuration of a connection state of a driver 6e, a rectangular wave generator 5b, and a switching circuit 5c in a stable oscillation section T2 in Z-Drive. It is. FIG. 2 is a diagram for explaining an angular velocity sensor 1 according to a first embodiment of the present invention, showing a schematic configuration of a connection state of a driver 6e, a rectangular wave generator 5b, and a switching circuit 5c in an oscillation stop period T3 in Z-Drive. It is. FIG. 2 is a diagram for explaining an angular velocity sensor 1 according to a first embodiment of the present invention, and showing a schematic configuration of a connection state of a driver 6e, a rectangular wave generator 5b, and a switching circuit 5c in an oscillation start section T1 in X-Drive. It is. FIG. 2 is a diagram for explaining an angular velocity sensor 1 according to a first embodiment of the present invention, and showing a schematic configuration of a connection state of a driver 6e, a rectangular wave generator 5b, and a switching circuit 5c in a stable oscillation section T2 in X-Drive. It is. FIG. 2 is a diagram for explaining an angular velocity sensor 1 according to a first embodiment of the present invention, and showing a schematic configuration of a connection state of a driver 6e, a rectangular wave generator 5b, and a switching circuit 5c in an oscillation stop period T3 in X-Drive. It is. It is a figure explaining the angular velocity sensor by the modification of 1st Embodiment of this invention, Comprising: It is a block diagram which shows schematic structure of the angular velocity sensor part 3 provided with the drive electrode D1X, D2X, D1Y, D2Y of 4 terminals. It is a figure for demonstrating the angular velocity sensor 1 in 2nd-1 embodiment from 2nd-1 embodiment of this invention. FIG. 10 is a diagram for explaining an integrated circuit according to embodiments 2-1 to 2-3 of the present invention. It is a figure which illustrates the drive signal applied to the drive electrode shown to Fig.30 (a) of this invention. It is a block diagram for demonstrating the structure of the angular velocity sensor drive circuit of 2nd-1 embodiment of this invention. It is a figure for demonstrating the drive signal by 2nd-1 embodiment of this invention. It is a figure for demonstrating the drive signal by 2nd-2 embodiment of this invention. It is a figure for demonstrating the drive signal by 2nd-3 embodiment of this invention. It is a block diagram of the integrated circuit of the angular velocity sensor of the 2-4 embodiment of the present invention. It is a block diagram for demonstrating the angular velocity sensor drive circuit shown in FIG. It is a figure for demonstrating the drive signal by 2-4 embodiment of this invention.

[First Embodiment]
An angular velocity sensor and a method for adjusting the angular velocity sensor according to the first embodiment of the present invention will be described with reference to FIGS. Before explaining the angular velocity sensor and the adjustment method of the angular velocity sensor according to the present embodiment, self-excited oscillation will be explained. In the present embodiment, the direction in which a vibration unit 3a to be described later vibrates will be described by setting an XYZ orthogonal coordinate system. When an oscillation control unit 5 described later functions as a Z-Drive, the vibration unit 3a vibrates in the Z-axis direction. When the oscillation control unit 5 functions as an X-Drive, the vibration unit 3a vibrates in the X-axis direction within the XY coordinate plane.

<About self-excited oscillation>
An angular velocity sensor having high vibration energy efficiency such as a piezoelectric element can perform self-excited oscillation. For example, the above-described conventional gyro (angular velocity sensor) forms an oscillation loop that feeds back one of detection signals detected by the detection electrodes X1 and X2 and outputs it as a drive signal.
If the open loop gain of the oscillation system is 0 dB, stable oscillation can be achieved. For example, in the case of Z-Drive, the carrier wave Vs is phase-shifted by 90 °, and the gain-amplified signal is driven to the drive electrodes D1 and D2 as the sine wave oscillation control unit output signal Vdr. On the other hand, in the case of X-Drive, the carrier wave Vsx is phase-shifted by 90 ° and the gain-amplified signal is driven to the drive electrodes D1 and D2 as sin-phase oscillation control unit output signals Vdrx and -Vdrx.

FIG. 1 is a diagram illustrating an example of frequency characteristics and envelope characteristics of an angular velocity sensor by an external drive. 1A shows the frequency characteristic of the angular velocity sensor, FIG. 1B is an enlarged view of the peak portion of the frequency characteristic shown in FIG. 1A, and FIG. 1C shows the angular velocity sensor. The envelope characteristic of the vibration locus | trajectory at the time of the vibration part oscillating and vibrating is shown. In FIG. 1A and FIG. 1B, the horizontal axis indicates the frequency, and the vertical axis indicates the gain. In FIG. 1C, the horizontal axis indicates time, and the vertical axis indicates voltage.
As shown in FIG. 1A, the angular velocity sensor can oscillate following the frequency of the maximum gain value of the BPF (Band Path Filter) characteristic of the angular velocity sensor unit.

In this embodiment, in such two self-excited oscillations, high-speed oscillation start, stable oscillation, and oscillation stop are realized, and Z-Drive and X-Drive are operated in a time-sharing manner to obtain a three-axis angular velocity. Detection is possible.
For example, the conventional excitation method for outputting a drive signal having a constant oscillation frequency to the drive electrode (drive electrode) has the following problems.
The gain peak of the angular velocity sensor is set as the oscillation frequency fsns, and the oscillation frequency of the external drive is set as fdr. In the conventional method, the oscillation period (frequency) of the external drive is only an integral multiple of the master clock. Therefore, as shown in FIG. 1B, the oscillation frequency fdr of the external drive and the oscillation frequency of the gain peak of the angular velocity sensor. A frequency error occurs between fsns.
As a result, the loss of gain increases. Further, as indicated by a curve L1 in FIG. 1C, a beat of Δf = fsns−fdr may occur and stable oscillation may not occur. A curve L2 shown in FIG. 1C shows an envelope of self-oscillation.
On the other hand, in self-excited oscillation, the oscillation frequency of the angular velocity sensor is naturally pulled into the gain peak value of the BPF characteristic of the angular velocity sensor unit. Therefore, stable oscillation can be realized even if the oscillation frequency varies with temperature.

<Z-Drive oscillation circuit and control method>
FIG. 2 is a circuit block diagram showing a schematic configuration of the angular velocity sensor 1.
As shown in FIG. 1, the angular velocity sensor 1 includes an angular velocity sensor unit 3 and an oscillation control unit 5. The angular velocity sensor unit 3 includes drive electrodes (drive electrodes) D1 and D2, detection electrodes X1, X2, Y1, and Y2, and a vibration unit 3a.
The oscillation control unit 5 outputs a drive signal to the self-excited oscillation circuit 5a constituting the oscillation loop, the rectangular wave generator (an example of the drive signal generation circuit) 5b, and the drive electrodes D1 and D2, or a self-excited oscillation signal. And a switching circuit (selector) 5c for switching whether to output. Furthermore, the oscillation control unit 5 includes a control unit 5f that controls the switching circuit (an example of the output unit) 5c so that the vibration start section for starting the vibration of the vibration section 3a and the angular velocity detection section for detecting the angular velocity are repeated. ing. The self-excited oscillation circuit 5a generates self-excited oscillation signals to be output to the drive electrodes D1 and D2 based on the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 detected by the vibration detection electrodes X1, X2, Y1, and Y2. The rectangular wave generator 5b generates a rectangular wave driving signal (rectangular wave driving signal) to be output to the drive electrodes D1, D2.
The self-excited oscillation circuit is an excitation circuit that generates an excitation signal based on a detection signal from the detection electrode.
The rectangular wave generator is a vibration start signal generation circuit that generates a vibration start signal.
The switching circuit is an output unit that outputs a vibration start signal to the drive electrode during a vibration start interval in which the vibration of the vibration unit is started, and outputs an excitation signal to the drive electrode during an angular velocity detection interval in which the angular velocity is detected.

FIG. 3 is a diagram showing a connection state of the oscillation control unit 5 in the oscillation start period when the oscillation control unit 5 functions as Z-Drive, and FIG. 4 shows the oscillation control unit 5 functioning as Z-Drive. It is a figure which shows the connection state of the oscillation control part 5 in the stable oscillation area at the time.
As shown in FIG. 3, in the oscillation start period, the angular velocity sensor unit 3 and the rectangular wave generator 5b are connected by the switching circuit 5c. In FIG. 3, the connection state between the rectangular wave generator 5b and the drive electrodes D1, D2 is shown by a straight line connecting the output terminal of the rectangular wave generator 5b and the drive electrodes D1, D2. The two output terminals of the rectangular wave generator 5b are short-circuited with each other, and the output signals Rct1 and Rct2 output from the two output terminals are input to the drive electrodes D1 and D2 as the oscillation control unit output signal Vdr. In the oscillation start period, the rectangular wave output from the rectangular wave generator 5b is driven to the drive electrodes D1 and D2, and the angular velocity sensor 1 is started up.

As shown in FIG. 4, in the stable oscillation section, the angular velocity sensor unit 3 and the driver 6e are connected by the switching circuit 5c. In FIG. 4, the connection state between the driver 6e and the drive electrodes D1, D2 is shown by a straight line connecting one output terminal of the driver 6e and the drive electrodes D1, D2. The self-excited oscillation signal Dr1 output from one output terminal of the driver 6e is input to the drive electrodes D1 and D2 as the oscillation control unit output signal Vdr. In the stable oscillation section, the self-excited oscillation circuit 5a of the oscillation control unit 5 has signals from the detection electrodes X1, X2, Y1, and Y2 as HPF (High Path Filter) 6a, carrier wave generation circuit 6b, phase shifter 6c, and variable amplifier. The self-excited oscillation circuit 5a is controlled so as to be input to the drive electrodes D1 and D2 via 6d and the driver 6e, and a 360 ° oscillation (positive feedback) loop is formed to stably oscillate. An HPF (High Path Filter) 6a, a carrier wave generation circuit 6b, a phase shifter 6c, a variable amplifier 6d, and a driver 6e are provided in the self-excited oscillation circuit 5a. The phase shifter 6c shifts the phase of the input signal by 90 ° and outputs it. The phase of the signal in the oscillation loop is shifted by 270 ° in the angular velocity sensor unit 3 and shifted by 90 ° in the phase shifter 6c. As a result, the phase of the signal in the oscillation loop is shifted by 360 °.

The connection state in the oscillation stop period is the same as that in the stable oscillation period, but the driver 6e can be switched to operate as a voltage follower in the stable oscillation period and to operate as an inverting amplifier in the oscillation stop period. Yes. In the oscillation stop period, the oscillation (positive feedback) loop in the stable oscillation period is inverted, and a 180 ° oscillation stop (negative feedback) loop that converges to the operating common voltage VCOM is formed in the self-excited oscillation circuit 5a, and the oscillation stops.
With this configuration, it is possible to realize intermittent driving that starts up at high speed and repeats self-excited oscillation and stoppage.

The oscillation control unit 5 includes a reference value generation unit 5d that generates a master clock and a voltage source, and a sequencer 5e that performs the above control in an oscillation start period, a stable oscillation period, and an oscillation stop period.
The sequencer 5e is a storage unit that stores amplitude information that determines the amplitude of the drive signal (rectangular wave drive signal) of the rectangular wave generator 5b or time information that determines the time during which the drive signal of the rectangular wave generator 5b is output. Have The sequencer 5e outputs the first amplitude information of the rectangular wave driving signal (an example of the first driving signal) output from the rectangular wave generator 5b in Z-Drive, and the rectangular wave generator 5b outputs in X-Drive described later. The second amplitude information of the rectangular wave driving signal (an example of the second driving signal) output from the rectangular wave generator 5b to be stored is stored. Further, the sequencer 5e stores first time information for outputting a rectangular wave drive signal in Z-Drive and second time information for outputting a rectangular wave drive signal in X-Drive. The sequencer 5e corresponds to an adjustment unit that adjusts the energy of the vibration start signal applied to the drive electrode during the next vibration start interval based on the amplitude of the detection signal or the excitation signal in the angular velocity detection interval or the amount of fluctuation of the amplitude. To do.

This self-excited oscillation is controlled by a control value based on the BPF characteristic of the angular velocity sensor unit 3 and the oscillation amplitude characteristic of the rising edge of the output signal output from the rectangular wave generator 5b.
The oscillation amplitude of the angular velocity sensor 1 is controlled by at least one of the amplitude of the rectangular wave at the start of oscillation and the driving time thereof.
In order to achieve stable oscillation in the self-excited oscillation, it is possible to control with the phase shift amount in the phase shifter 6c in the oscillation loop and the control value for gain adjustment in the variable amplifier 6d.

In Z-Drive, the vibration unit 3a of the angular velocity sensor unit 3 vibrates in the Z-axis direction, and the Y-axis angular velocity ωy is generated in the orthogonal component of the carrier wave of the detection electrodes X1 and X2, and the detection signal from the detection electrodes X1 and X2 It is detected as a difference or phase difference between Vs_x1 and Vs_x2. On the other hand, the X-axis angular velocity ωx is generated in the orthogonal component of the carrier waves of the detection electrodes Y1 and Y2, and is detected as a difference or phase difference between the detection signals Vs_y1 and Vs_y2 from the detection electrodes Y1 and Y2.
Further, due to the BPF characteristics of the angular velocity sensor unit 3, the in-phase oscillation control unit output signal Vdr applied to the drive electrodes D1 and D2, respectively, undergoes gain fluctuation and 270 ° phase shift, and the detection electrodes X1, X2, Y1, The detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 are output from Y2.

Next, a circuit inside the oscillation loop will be described in detail.
The HPF 6a is a resistor connected between the capacitive electrode having the detection electrodes X1, X2, Y1, and Y2 of the angular velocity sensor unit 3 as one electrode and the other electrode of the capacitive element and the operation common voltage VCOM. It consists only of and. That is, the HPF 6a is a passive high-pass filter circuit. The HPF 6a is provided for each of the detection electrodes X1, X2, Y1, and Y2.
The carrier wave generation circuit 6b generates the carrier wave Vs as described above. The carrier wave Vs is obtained from the following equation.
Vs = (Vs_x1 + Vs_x2 + Vs_y1 + Vs_y2) / 4
Although the details will be described later, the phase shifter 6c has a so-called all-pass filter circuit, and makes at least one of the resistance value of the resistor and the capacitance value of the capacitive element constituting the all-pass filter circuit variable. Thus, the phase shift amount Sft can be adjusted.

The variable amplifier 6d is composed of an inverting amplifier, an attenuator, and the like, and the gain A can be adjusted by making the resistance value variable.
The driver 6e operates as a voltage follower when forming a 360 ° oscillation (positive feedback) loop, and operates as an inverting amplifier (inversion gain -B) when forming a 180 ° oscillation stop (negative feedback) loop. In the case of Z-Drive, the two self-excited oscillation signals Dr1 and Dr2 output from the driver 6e are the same signal.
The rectangular wave generator 5b is orthogonal to the rectangular wave drive signal (an example of the first drive signal) that vibrates the vibration part 3a in the Z-axis (an example of the first axis) and the vibration part 3a in the Z-axis direction. A rectangular wave drive signal (an example of the second drive signal) that causes the X axis (an example of the second axis) to vibrate is output.

The rectangular wave generator 5b outputs a rectangular wave driving voltage Vrct having a frequency fdr substantially equal to the oscillation frequency of the angular velocity sensor unit 3 with an amplitude Vup and a driving time Tup. The amplitude of self-oscillation can be adjusted substantially in proportion to the amplitude Vup and the drive time Tup. The two rectangular wave drive signals Rct1 and Rct2 output from the rectangular wave generator 5b are the same signal.
The switching circuit 5c can connect the drive electrodes D1 and D2 by selecting the rectangular wave drive signals Rct1 and Rct2 and the self-excited oscillation signals Dr1 and Dr2 output from the driver 6e. The switching circuit 5c outputs a rectangular wave drive signal Vrct to vibrate the vibration unit 3a, and then switches to output a self-excited oscillation signal.
The control unit 5f controls the output unit 5c so that the first vibration start section, the first angular velocity detection section, the second vibration start section, and the second angular speed detection section (details of each section will be described later) are repeated.

The reference value needs a certain degree of accuracy. The master clock MCLK may be free-running oscillation that is asynchronous with the carrier wave. The reference value generator 5d outputs an operation common voltage VCOM, a reference voltage VREF, and a master clock MCLK (oscillation frequency fclk).
The angular velocity is a component orthogonal to the carrier wave, and the carrier wave (represented by, for example, the symbol “Vs” in FIG. 2) is a signal that is phase-shifted by 90 ° or 270 ° in the angular velocity detection, and is called an orthogonal signal Q. Furthermore, signals that are 90 ° phase shifted from the carrier wave (represented by the symbols “Vi”, “Via”, and “Vdr” in FIG. 2, for example) are phase shifted by 0 ° or 180 ° in angular velocity detection. This signal is synchronized with the signal and is called an in-phase signal I. The angular velocity is detected in a state where the carrier wave is modulated, and the detection signal is demodulated by the in-phase signal I and detected by removing the carrier wave which is a quadrature component. In FIG. 2, the output signal Via which is the output of the variable amplifier 6d can be used as the in-phase signal I in the angular velocity detection.

In FIG. 2, the angular velocity sensor 1 includes a monitor unit (an example of an amplitude detection unit) 1a that monitors a carrier wave Vs and a monitor unit (an example of an amplitude detection unit) 1b that monitors an output signal Via. The quadrature signal Q is monitored, and the monitor unit 1b monitors the in-phase signal I. The

monitor units

1a and 1b detect the amplitude of the self-excited oscillation signal in the self-excited oscillation circuit 5a, the amplitude detection signal which is the amplitude of the detected self-excited oscillation signal, the amplitude information of the carrier wave held by the

monitor units

1a and 1b, and Based on the frequency information, the amplitude of the rectangular wave drive signal of the rectangular wave generator 5b or the time (period) during which the rectangular wave drive signal is output may be adjusted.

The control data of the oscillation controller 5 is preferably a digital value in order to easily perform a time division operation. Data stored in the sequencer 5e is the following count value Nf, control value dtsft, and gain control value dtA. Here, the count value Nf is a count value of a sensor oscillation signal that is an oscillation signal oscillating at an oscillation frequency of the angular velocity sensor unit 3 in Z-Drive and a count value of a rectangular wave period CLK of a rectangular wave drive signal. The frequency fdr of the rectangular wave drive signal is set to a value (fclk / Nf) obtained by dividing the oscillation frequency fclk of the angular velocity sensor unit 3 by the counter value Nf in Z-Drive. The control value dtSft is a control value of the phase shift amount Sft of the carrier wave Vsz in the phase shifter 6c. The gain control value dtA is a control value of the carrier wave gain A in the variable amplifier 6d.

Further, the data stored in the sequencer 5e by adjusting the amplitude and control time of the rectangular wave so as to obtain the target amplitude from the start of oscillation of the angular velocity sensor 1 to the self-excited oscillation are the control value dtRct and the master clock. The count value Nup. Here, the control value dtRct is a control value for controlling the rectangular wave amplitude Vrct which is the amplitude of the rectangular wave drive signal Rct, and the master clock count value Nup is the count value of the master clock MCLK in the rectangular wave drive time Tup. It is. The rectangular wave driving time Tup is a driving time for driving the drive electrodes D1 and D2 by the rectangular wave generator 5b.

<X-Drive Oscillator Circuit and Control Method>
Next, a configuration in which the oscillation control unit 5 functions as an X-Drive will be described with reference to FIGS. 5 and 6 with reference to FIG.
The configuration when the oscillation control unit 5 functions as X-Drive differs in the behavior of the angular velocity sensor 1, but the oscillation control unit 5 is different only in the circuit configuration of the carrier wave generation circuit 6b and the control method of the switching circuit 5c. The circuit configuration in the case of functioning as Z-Drive is the same. Therefore, the oscillation control unit 5 can be shared by X-Drive and Z-Drive. The main differences between the case where the oscillation control unit 5 functions as X-Drive and the case where it functions as Z-Drive will be described.

When the vibration unit 3a of the angular velocity sensor unit 3 is vibrated in the X-axis direction, the Z-axis angular velocity ωz is generated as a quadrature component of the carrier waves of the detection electrodes Y1 and Y2, and is detected as a difference between the detection signal Vsx_y1 and the detection signal Vsx_y2. .
Further, due to the BPF characteristics of the angular velocity sensor unit 3, the oscillation control unit output signal Vdrx and the oscillation control unit output signal −Vdxr applied to the drive electrodes D1 and D2 in reverse phase are phase-shifted by 270 ° to detect electrodes. A detection signal Vsx_x1 and a detection signal Vsx_x2 having opposite phases are output from X1 and X2.
The carrier wave generation circuit 6b detects the carrier wave Vsx as described above. The carrier wave Vsx is obtained as follows.
Vsx = (Vsx_x1-Vsx_x2) / 2

FIG. 5 is a diagram illustrating a connection state of the oscillation control unit 5 in the oscillation start period when the oscillation control unit 5 functions as an X-Drive.
As shown in FIG. 5, in the oscillation start section, the angular velocity sensor unit 3 and the rectangular wave generator 5b are connected by the switching circuit 5c. In FIG. 5, the connection state between the rectangular wave generator 5b and the drive electrodes D1, D2 is shown by a straight line connecting the output terminal of the rectangular wave generator 5b and the drive electrodes D1, D2. The rectangular wave drive signal Rct1 output from the output terminal of the rectangular wave generator 5b is input to the drive electrode D1 as the oscillation control unit output signal Vdrx, and is output from the other output terminal of the rectangular wave generator 5b. Is input to the drive electrode D2 as the oscillation control unit output signal -Vdrx. Note that the rectangular wave drive signals Rct1x and Rct2x of the rectangular wave generator 5b are rectangular waves having opposite phases, and the oscillation control unit output signals Vdrx and -Vdrx are signals having opposite phases.

FIG. 6 is a diagram illustrating a connection state of the oscillation control unit 5 in a stable oscillation section when the oscillation control unit 5 functions as an X-Drive. In the stable oscillation period, the angular velocity sensor unit 3 and the driver 6e are connected by the switching circuit 5c. In FIG. 6, the connection state between the driver 6e and the drive electrodes D1, D2 is shown by a straight line connecting the output terminal of the driver 6e and the drive electrodes D1, D2. The self-excited oscillation signal Dr1x output from one output terminal of the driver 6e is input to the drive electrode D1 as the oscillation control unit output signal Vdrx, and the self-excited oscillation signal Dr2x output from the other output terminal of the driver 6e is output from the oscillation control unit The signal -Vdrx is input to the drive electrode D2.

When the oscillation control unit 5 functions as X-Drive, the driver 6e operates as a voltage follower during a 360 ° oscillation (positive feedback) loop in a stable oscillation period. The driver 6e operates as an inverting amplifier during a 180 ° oscillation stop (negative feedback) loop in the oscillation stop period. Here, the self-excited oscillation signals Dr1x and Dr2x of the driver 6e are drive signals having opposite phases.
The rectangular wave generator 5b can adjust the amplitude of self-oscillation in substantially proportion to the amplitude and driving time of the rectangular wave driving signal.
The switching circuit 5c can select and input the rectangular wave drive signals Rct1x and Rct2x and the self-excited oscillation signals Vdrx1 and Vdr2x to the drive electrodes D1 and D2 as the oscillation control unit output signals Vdrx and −Vdrx.

The data stored in the sequencer 5e is the same type of data as Z-Drive as follows. The count value NfX is a count value of a sensor oscillation signal that is an oscillation signal oscillating at the oscillation frequency of the angular velocity sensor unit 3 in X-Drive, and a count value of a rectangular wave period CLK of the rectangular wave drive signal. The frequency fdr of the rectangular wave drive signal is set to a value (fclk / NfX) obtained by dividing the oscillation frequency fclk of the angular velocity sensor unit 3 by the counter value NfX in X-Drive. The control value dtSftX is a control value of the phase shift amount SftX of the carrier wave Vsx in the phase shifter 6c. The gain control value dtAX is a control value of the carrier wave gain AX. The control value dtRctX is a control value of the rectangular wave amplitude VrctX in the variable amplifier 6d. The count value NupX is a count value of the rectangular wave period CLK of the rectangular wave driving time TupX.

<Time-sharing operation of Z-Drive and X-Drive>
FIG. 7 is an image diagram of time-division operation in the angular velocity sensor 1. FIG. 7A shows a timing chart of the next division operation in the angular velocity sensor 1, and FIG. 7B shows an enlarged timing chart in Z-Drive. The upper part of FIG. 7A schematically shows Z-Drive and X-Drive operation sections, and the lower part of FIG. 7A shows the oscillation start section T1 and the stable state in each of the Z-Drive and X-Drive operation sections. The timings of the oscillation period T2 and the oscillation stop period T3 are shown. The first stage in FIG. 7B schematically shows the Z-Drive operation section, and the second stage in the figure shows the oscillation start section T1, the stable oscillation section T2, and the oscillation stop section in the Z-Drive operation section. The timing of T3 is shown, the third stage in the figure shows the voltage waveform of the oscillation control unit output signal Vdr inputted to the drive electrodes D1 and D2, and the fourth stage in the figure shows the voltage waveform of the carrier wave Vsz. In FIG. 7A and FIG. 7B, the horizontal axis indicates time, and the passage of time is represented from left to right in the drawing. The Z-Drive oscillation start interval T1 corresponds to the first vibration start interval, the Z-Drive stable oscillation interval T2 corresponds to the first angular velocity detection interval, and the X-Drive oscillation start interval T1 corresponds to the second vibration start interval T1. The X-Drive stable oscillation period T2 corresponds to the start period, and corresponds to the second angular velocity detection period.

As shown in FIG. 7A, assuming that one measurement time is T (for example, 10 milliseconds (ms)), Z-Drive and X-Drive each have T1 + T2 + T3 (for example, 4 ms) as an oscillation start period T1 (for example, 1 ms), oscillation control is performed in three states of a stable oscillation period T2 (for example, 2 ms) and an oscillation stop period T3 (for example, 1 ms). The angular velocity is detected in the stable oscillation section T2. Note that the interval section of each of the Z-Drive and X-Drive operation sections is, for example, 1 ms.

When a distortion component such as odd-order distortion is generated in the carrier wave Vs, the distortion component is generated with a phase shift of 90 ° with respect to the carrier wave Vs, and becomes an in-phase component of angular velocity and becomes a noise component. Therefore, it is preferable that the carrier wave has less distortion.
In the present embodiment, the state switching is performed by the driver 6e and the switching circuit 5c. Even if noise occurs in the oscillation control unit output signal Vdr at the time of switching, the noise does not propagate to the carrier wave Vs. This is because the angular velocity sensor unit 3 has a narrow band BPF characteristic, and noise of the oscillation control unit output signal Vdr generated at the time of switching is removed. Therefore, even when the state is controlled by a signal asynchronous with the oscillation signal (for example, the CLK signal), a carrier wave with less distortion can be obtained. Note that the detection signal output from the detection electrode also becomes a sine wave with less distortion due to the BFP characteristics of the angular velocity sensor unit.

<Self-excited oscillation>
As shown in FIG. 7, the self-excited oscillation operation is composed of the following three states.
As shown in FIG. 7B, in the oscillation start period T1, a rectangular wave drive signal Rct1 having a period fclk / Nf close to the oscillation frequency fclk of the angular velocity sensor unit 3 is applied to the drive electrodes D1 and D2 as an oscillation control unit output signal Vdr. Driving is performed to start the vibration of the vibration unit 3a, and the amplitude Vrct and the drive time DTrt (= Nup / fclk) are controlled so that the rectangular wave drive signal Rct1, that is, the oscillation control unit output signal Vdr, has a desired amplitude.

In the stable oscillation period T2, the phase shift amount Sft of the phase shifter 6c and the gain A of the variable amplifier 6d are controlled. A 360 ° oscillation (positive feedback) loop is formed. As shown in FIG. 7B, since the stable oscillation period T2 (self-excited oscillation period) is a short period, even if there is a slight error in the phase shift amount Sft and the gain A, the oscillation amplitude of the self-excited oscillation signal Dr, that is, the oscillation The amplitude of the control unit output signal Vdr can be maintained at a constant value. In this section, the angular velocity is detected with the in-phase signal.
In the oscillation stop period T3, the self-excited oscillation circuit 5a inverts the oscillation (positive feedback) loop to form a 180 ° oscillation stop (negative feedback) loop. As a result, the amplitude is reduced, converged to the operating common voltage VCOM, and oscillation stops.
In the case of X-Drive, the same operation as described above is performed.

<Adjustment value setting method>
Next, a method for setting each adjustment value from the open loop characteristics of the angular velocity sensor 1 will be described.
In order to stably vibrate the vibration part, it is necessary to accurately match the drive signal with the resonance frequency of the vibration part of the angular velocity sensor. For this reason, it is necessary that the oscillation frequency of the drive signal output to the drive electrode be highly accurate, but it is usually very difficult to adjust and control the oscillation frequency of the drive signal. However, with the adjustment according to the present embodiment, adjustment or control can be easily performed with high accuracy.
The frequency characteristics of the angular velocity sensor unit 3 during Z-Drive are as follows. The carrier wave detected by the detection electrodes X1, X2, Y1, and Y2 by driving the frequency-swept sine wave oscillation control unit output signal Vdr to the drive electrodes D1 and D2. It is obtained by measuring the gain of Vsz (= (Vs_x1 + Vs_x2 + Vs_y1 + Vs_y2) / 4). The frequency characteristic of the angular velocity sensor unit 3 is a narrow band BPF characteristic.
The adjustment value is determined by the frequency characteristics of the angular velocity sensor unit 3.
Nf: sensor oscillation frequency fz → period of rectangular wave, CLK count value Nsft: adjustment value of phase shifter to be shift amount 1 / (4 fz) dtA: sensor gain 1 / A → data in which gain of oscillation control unit is A ( (Adjustment value for stable oscillation at a total gain of 0 dB) In this state, stable oscillation is possible.

<Adjustment value setting method using monitor>
As described above, the set value can be obtained from the BPF characteristic of the angular velocity sensor unit 3, but the measurement time of the BPF characteristic of the angular velocity sensor unit 3 is not short, and the number of testers that can be measured is limited. Lack.
Adjustment of the frequency is indispensable for oscillation, and since the angular velocity is proportional to the carrier wave, it is also necessary to control the oscillation amplitude. The oscillation amplitude never exceeds a large. However, since the distortion generated by the power supply limit of the oscillation control unit 5 and the vibration limit of the angular velocity sensor unit 3 becomes a signal synchronized with the angular velocity, it is necessary to select an appropriate value suitable for the system as the frequency of the angular velocity sensor. is there.

Therefore, an adjustment method is proposed in which means for monitoring the quadrature signal Q = Vs and the in-phase signal I = Via is added. One means for monitoring here is a comparator, and the other is an ADC (analog-digital converter) for measuring amplitude. The comparator compares the input wave with the operating common voltage VCOM and detects the zero-cross timing of the input wave. The amplitude measurement ADC converts the amplitude value into a digital code.
As described above, the carrier wave Vs is called the quadrature signal Q, and the output signal Via of the variable amplifier 6d is called the in-phase signal I. Therefore, monitoring of the carrier wave Vsz in Z-Drive is executed by the comparator and ADC constituting the monitor unit 1a, and monitoring of the oscillation control unit output signal Vdr is executed only by the comparator constituting the monitor unit 1b.

FIG. 8 shows information obtained from each monitor when the output of the comparator provided in the monitor unit 1a is the output signal COMPQ and the output of the comparator provided in the monitor unit 1b is the output signal COMPI. In FIG. 8, the first stage shows the voltage waveform Vq of the carrier wave Vs, the second stage shows the voltage waveform of the output signal COMPQ of the comparator Q of the monitor unit 1a, and the third stage shows the output signal Via of the variable amplifier 6d. The voltage waveform is shown, and the fourth stage shows the voltage waveform of the output signal COMPI of the comparator of the monitor unit 1b. The vertical axis represents voltage, the horizontal axis represents time, and in FIG. 8, the passage of time is represented from left to right.

The carrier wave amplitude detected by the ADC is defined as AQ. The first rise time of the output signal of the comparator of the monitor unit 1a is defined as tQ (0), the second rise time is defined as tQ (1), and the (n-1) th rise time is defined as tQ (n). Define. Also, the first rise time of the output signal of the comparator of the monitor unit 1b is defined as tI (0), the second rise time is defined as tI (1), and the (n-1) th rise time is defined as tI (n ). Here, if the frequency of the rectangular wave periodic clock signal is fclk, the following information is obtained and control is possible.
The count value Nf of the oscillation period of the angular velocity sensor 1 is obtained by “tQ (n + 1) −tQ (n)) / fclk”. The count value Nsft of the phase shift amount of the phase shifter 6c is obtained by “tI (n) −tQ (n)) / fclk”.
Therefore, the phase shifter 6c is controlled by a control value dtSft in which the count value Nf is four times the count value Nsft of the phase shift amount, that is, “Nf = 4 × Nsft”.

<Acquisition of frequency data>
As described above, when the self-excited oscillation circuit 5a oscillates by forming a 360 ° oscillation (positive feedback) loop, the angular velocity sensor unit 3 pulls to a frequency having the maximum gain of the BPF characteristic of the angular velocity sensor unit 3. It oscillates. Therefore, at this time, if the carrier wave Vs and the output signal Via of the variable amplifier 6d are measured as described above, the sensor oscillation count value Nf, the rectangular wave period clock signal count value Nf, and the phase shift amount count value Nsft are obtained. It is done.

<Adjustment method at the start of oscillation>
A method for adjusting the oscillation amplitude of the oscillation control unit output signal when the rectangular wave drive signal at the start of oscillation of the oscillation unit 3a is used as the oscillation control unit output signal will be described with reference to FIGS. FIG. 9 is a diagram illustrating a method for adjusting the oscillation amplitude of the rectangular wave drive signal output from the rectangular wave generator 5b. FIG. 9A is a diagram illustrating envelope characteristics of the carrier wave Vs in the oscillation start period and the stable oscillation period. The horizontal axis represents time (ms), and the vertical axis represents the amplitude voltage (Vpp) of the carrier wave Vs. The amplitude voltage is a potential difference between the maximum voltage value and the minimum voltage value of the carrier wave Vs. A curve L3 shows the envelope characteristic of the carrier wave Vs when the oscillation amplitude of the rectangular wave drive signal is not adjusted, a curve L4 shows the envelope characteristic of the carrier wave Vs when oscillated only by self-excited oscillation, and the curve L5 is The envelope characteristic of the carrier wave Vs when the oscillation amplitude of the rectangular wave drive signal is adjusted is shown. The target amplitude value Vcw is a target value for preventing the beat from occurring in the stable oscillation period with a short rise time of the carrier wave Vs. FIG. 9B shows the amplitude characteristics of the oscillation control unit output signal input to the drive electrodes D1 and D2. The horizontal axis represents time (ms), and the vertical axis represents the amplitude voltage (Vpp) of the oscillation control unit output signal. FIG. 9C shows the amplitude characteristic of the carrier wave Vs after adjusting the rectangular wave drive signal. The horizontal axis represents time (ms), and the vertical axis represents the amplitude voltage (Vpp) of the carrier wave Vs.

The frequency of the rectangular wave driving signal output from the rectangular wave generator 5b is controlled by the count value Nf of the rectangular wave periodic clock signal obtained previously. The oscillation amplitude of the rectangular wave is monitored by the ADC.
At the start of oscillation of the vibration unit 3a, the angular velocity sensor unit 3 and the rectangular wave generator 5b are connected, so that the oscillation unit 3a is open loop and operates regardless of the gains of the angular velocity sensor unit 3 and the oscillation control unit 5. . However, in this example, description will be made assuming that the sensor gain is 1 time and the gain of the oscillation control unit 5 is also 1 time. That is, during stable oscillation, if the amplitude voltage Vpp of the carrier wave Vs is 0.5V, the amplitude voltage Vpp of the oscillation control unit output signal Vdr is 0.5V.

Here, for example, the amplitude voltage of the carrier wave Vs that is a sine wave is three times (1.5 Vpp), the period is an integral multiple of the master clock MCLK, and the rectangular wave has a slight error from the oscillation period of the angular velocity sensor unit 3. Is continuously driven to the drive electrodes D1 and D2, the detection signal waveforms detected by the detection electrodes X1, X2, Y1, and Y2 are removed from the harmonics due to the BPF characteristics of the angular velocity sensor unit 3, and clean sin. Become a wave. Further, as shown in FIG. 9A, the rise of the envelope (curve L3) of the carrier wave Vs by the external drive (that is, drive by the rectangular wave generator 5b) is compared with the rise of the self-excited oscillation envelope (curve L4). And it rises about 3 times faster in a straight line. The rise of the envelope of the carrier wave Vs due to the external drive gradually approaches the exponential characteristic from the linear characteristic, and finally the oscillation period of the angular velocity sensor unit 3 and the oscillation control unit output signal that drives the drive electrodes D1 and D2 The period error with the period becomes a beat, and the carrier wave Vs fluctuates.

However, the oscillation amplitude characteristic in the oscillation start section T1 (for example, 1 ms) is a linear characteristic, and since there is no frequency error when switching to loop oscillation, no fluctuation occurs. Since this oscillation amplitude characteristic is proportional to the amplitude of the rectangular wave drive signal and the drive time, it can be controlled as follows.
The target amplitude value Vcw of the carrier wave is adjusted by setting the amplitude voltage Vpp to 0.5V.
First, the rectangular wave generator 5b sets the amplitude voltage Vpp of the rectangular wave driving voltage Vrct of the rectangular wave driving signal Rct1 to 1.5 V, sets the rectangular wave driving time Tup to 1 ms, and is counted by the count value Nf of the rectangular wave period clock signal. A rectangular wave with a specified period is output.

If the detected wave obtained at this time is a sin wave of αVcw (= 0.6 Vpp, α = 1.2), the amplitude voltage Vpp of the rectangular wave drive voltage Vrct is 1.25 times (Vup / α = 1. 25Vpp). Alternatively, the driving time Tup is increased by 0.8333 times (Tup / α = 0.8333 Tup). Such control enables detection amplitude control during stable oscillation.
The amplitude adjustment value of the rectangular wave drive signal Rct is determined to be an adjustment value that is 1.25 Vpp, and the drive time Nup that is driven by the rectangular wave drive signal Rct is a count of the rectangular wave period clock signal that causes the oscillation start period T1 to be 1 ms. Determined by value.
Alternatively, the adjustment value can be determined as follows.
The amplitude adjustment value of the rectangular wave drive signal Rct is determined to be an adjustment value that is 1.5 times the amplitude voltage Vpp (1.5 Vpp), and the drive time Nup is the count value of the rectangular wave period clock signal during the oscillation start period T1. To be determined.

10 and 11 are diagrams for explaining a method of adjusting the oscillation amplitude of the rectangular wave drive signal output from the rectangular wave generator 5b. FIG. 10 shows an example in which a beat is prevented from occurring in the carrier wave Vs by adjusting the oscillation amplitude of the rectangular wave drive signal. FIG. 11 shows an example of preventing a beat from occurring in the carrier wave Vs by adjusting the driving time of the rectangular wave driving signal. 10 (a) and 11 (a) are illustrated in the same manner as in FIG. 9 (a), and FIGS. 10 (b) and 11 (b) are similar to those in FIG. 9 (b). 10 (c) and 11 (c) are illustrated in the same manner as FIG. 9 (c).
As shown in FIG. 10B, the rectangular wave drive voltage Vrct of the rectangular wave drive signal in the oscillation start period is adjusted, and the amplitude voltage of the carrier wave Vs is set to the target amplitude value Vcw as shown in FIG. To do.
As shown in FIG. 11B, the drive time for driving the drive electrodes D1, D2 is adjusted to be short with the rectangular wave output amplitude, and the amplitude voltage of the carrier wave Vs is set to the target as shown in FIG. 11C. Set to the amplitude value Vcw.

Thus, the amplitude information (an example of the first amplitude information) and the time information (an example of the first time information) of the rectangular wave output signal are determined by the envelope of the detection signal (for example, the carrier wave Vs). While the envelope of the detection signal (for example, the carrier wave Vs) has a linear characteristic, the switching circuit 5c switches so as to output the oscillation control unit output signal based on the self-excited oscillation signal from the oscillation control unit output signal based on the rectangular wave drive signal Rct. . When the switching circuit 5c switches to output a self-excited oscillation signal from the self-excited oscillation circuit 5a after outputting the rectangular wave drive signal as an oscillation control unit output signal to vibrate the vibration unit 3a, the monitor unit When the amplitude detection signals monitored by 1a and 1b are greater than or equal to a predetermined value, adjustment is made to reduce the amplitude of the drive signal, or adjustment to shorten the time during which the rectangular wave drive signal is output as the oscillation control unit output signal. . In addition, when the amplitude of the detection signal (for example, the carrier wave Vs) is not linear with respect to the output time of the detection signal, adjustment to reduce the amplitude of the rectangular wave drive signal or shorten the time for outputting the rectangular wave drive signal. Make adjustments.

<Adjustment method for stable oscillation>
FIG. 12 is a diagram schematically showing the oscillation amplitude characteristic of the carrier wave Vs when the angular velocity sensor 1 continuously oscillates. The vertical axis represents the amplitude voltage Vpp of the carrier wave Vs, and the horizontal axis represents time. The passage of time is shown from left to right in the figure.
The oscillation of the angular velocity sensor 1 is maintained from the above state unless a stop operation is performed. Here, if the loop gain is 1 (for example, the gain of the angular velocity sensor unit 3 is 1 / A and the gain of the variable amplifier 6d is A), as shown by a curve L5 in FIG. The oscillation amplitude of Vs is maintained at a constant value. On the other hand, the oscillation amplitude of the carrier wave Vs gradually increases if the loop gain is greater than 1 (see curve L6), and gradually decreases if the loop gain is less than 1 (see curve L7). However, even with the oscillation of the angular velocity sensor unit having a relatively low Q value, the time change is small.

After the above-described oscillation start operation, an oscillation loop is formed. At this time, the oscillation amplitude of the carrier wave Vs is measured by the ADC of the monitor unit 1a at a sampling rate of about 0.5 ms. In the adjustment determination, the amplitude AQ (n−1) before one sampling is compared with the current amplitude AQ (n), and when the difference exceeds the threshold value + ΔTH, the loop gain is larger than 1, and the difference is the threshold value. When the value is less than −ΔTH, the loop gain is smaller than 1. Therefore, adjustment for changing the gain of the variable amplifier 6d is performed.
More specifically, it is as follows.
When the difference of “AQ (n) −AQ (n−1)” exceeds the threshold value + ΔTH, adjustment is performed to lower the gain of the variable amplifier 6d.
The difference between “AQ (n) −AQ (n−1)” is equal to or smaller than the threshold −ΔTH (threshold having the same absolute value as the threshold TH and having a minus sign (−). The negative threshold is “−TH”. In some cases, the gain of the variable amplifier 6d is adjusted to increase.
When the difference of “AQ (n) −AQ (n−1)” is equal to or less than the threshold + ΔTH and equal to or greater than −ΔTH, the gain of the variable amplifier 6d is maintained.
As a result, stable oscillation when a self-excited oscillation loop is formed can be realized.
Also, the oscillation stop operation is necessary even in the above-described oscillation operation.

FIG. 13 is a diagram schematically illustrating an example of the adjustment of the oscillation amplitude of the carrier wave Vs when the loop gain of the oscillation control unit 5 is greater than one. 13A and 13B show the oscillation amplitude characteristics of the oscillation control unit 5, the middle stage shows the loop gain of the oscillation control unit 5, and the lower part of the figure. Shows the adjustment determination result. In the oscillation amplitude characteristic of the oscillation control unit 5 in the upper stage in the figure, the vertical axis indicates the amplitude voltage Vpp of the carrier wave Vs, the horizontal axis indicates time, and the time passage is shown from left to right in the figure. In the figure, the middle and lower rectangular frames indicate the timing of oscillation amplitude adjustment, and adjustment determination and oscillation amplitude adjustment are performed for each rectangular frame. The numerical value in the rectangular frame in the middle of the figure represents the loop gain of the oscillation control unit 5. In the figure, the equal sign in the rectangular frame at the bottom indicates that the amplitude value of the previous sample is equal to the current amplitude value, and the inequality sign (>) indicates that the amplitude value of the previous sample is greater than the current amplitude value. The inequality sign (<) indicates that the amplitude value one sample before is smaller than the current amplitude value, and the equal sign (=) indicates that the amplitude value one sample before is the same as the current amplitude value.

As shown in the upper part of FIG. 13A, the oscillation control unit 5 forms an oscillation loop after the oscillation operation of the oscillation control unit 5, that is, after the rectangular wave driving time Tup has elapsed. The oscillation amplitude is measured at a sampling rate of about 0.5 ms. The gain of the oscillation control unit 5 is adjusted according to the adjustment determination described above. As shown in the lower part of FIG. 13A, in this example, the adjustment determination for increasing the oscillation amplitude continues, and as shown in the middle part of FIG. 13A, the oscillation loop of the oscillation control unit 5 is increased. When the gain reaches 0.88, the gain is maintained. After that, the adjustment determination result that the amplitude value one sample before and the current amplitude value are equal (=) is obtained four times in succession. As a result, the oscillation control unit 5 determines that the amplitude adjustment has been completed, forms a −1 times inversion loop, and stops oscillation. Since the target amplitude value Vcw is, for example, 1.2 V, the oscillation control unit 5 determines that there is no problem with the amplitude value of the carrier wave Vs. When the amplitude value of the carrier wave Vs is greatly deviated from the target amplitude value Vcw, the adjustment gain is set, and the above operation is repeated once more so that a more accurate adjustment value of the oscillation amplitude of the carrier wave Vs can be obtained. .

If the above-described adjustment is performed, as shown in FIG. 13B, the oscillation amplitude of the carrier wave Vs is controlled by the rectangular wave output signal Vrct output from the rectangular wave generator 5b to become the target amplitude value Vcw. Since the oscillation amplitude of the carrier wave Vs is also adjusted in gain, the target amplitude value Vcw is maintained.
FIG. 14 is a diagram schematically illustrating an example of the oscillation amplitude adjustment of the carrier wave Vs when the loop gain of the oscillation control unit 5 is smaller than 1. The method shown in FIG. 14A is the same as the method shown in FIG. 13A, and the method shown in FIG. 14B is the same as the method shown in FIG. 13B. The description is omitted.
As shown in the lower part of FIG. 14A, in this example, the adjustment determination for decreasing the oscillation amplitude continues, and as shown in the middle part of FIG. 14A, the oscillation loop of the oscillation control unit 5 When the gain reaches 1.12, the gain is maintained. Thereafter, the amplitude adjustment of the carrier wave Vs is performed by the same control as described with reference to FIG.

<Adjustment procedure>
Next, the procedure for adjusting the amplitude of the carrier wave Vs will be described with reference to FIGS.
(Silicon device adjustment)
First, the oscillation control unit 5 needs to be adjusted. Usually, the oscillation control unit 5 is manufactured by a CMOS (Complementary MOS (Metal-Oxide-Semiconductor): complementary MOS) silicon device.
Although the oscillation control unit 5 having a high temperature and power supply voltage drift tolerance can be arranged, the oscillation control unit 5 is sensitive to variations in resistance and capacitance. In particular, the phase shifter 6c is sensitive to variations in resistance and capacitance, and it is necessary to adjust the amount of phase shift. Therefore, the voltage source, the current source, the frequency of the master clock MCLK, the target value of the phase shift amount of the phase shifter 6c, and the like are measured. Store in a nonvolatile memory such as Programmable ROM). The nonvolatile memory is provided in the sequencer 5e, for example. Since this procedure can be performed even before the module assembly process, it is preferable to perform this procedure at the time of a screening test of a single CMOS device.

Here, the adjustment procedure of the silicon device will be described with reference to FIG. FIG. 15 is a flowchart illustrating an example of a flow of a silicon device adjustment procedure.
The adjustment procedure shown in FIG. 15 is executed, for example, in a screening test for a single COMS device before the module assembly process.
In the adjustment procedure of the silicon device, first, in step S1, the reference value generating unit 5d is adjusted, and the process proceeds to step S3. In step S1, the voltage value of the operation common voltage VCOM output from the reference value generator 5d, the voltage value of the reference voltage VREF, and the frequency of the master clock MCLK are adjusted. The reference voltage VREF is used as a reference voltage for generating the output voltage of the voltage source and the output current of the current source.

In step S3, the phase shifter characteristics are confirmed, and the process proceeds to step S5. In step S3, the phase shifter amount of the phase shifter 6c, the target value of the phase shift amount, and the like are measured and confirmed.
In step S5, each value confirmed in step S3 is written in the memory, and the silicon device adjustment procedure is completed. In step S5, the phase shifter amount of the phase shifter 6c, the target value of the phase shifter amount, the frequency of the master clock MCLK, and the like are written in the nonvolatile memory (not shown) provided in the sequencer 5e.

Next, specific processing of sensor module adjustment and oscillation frequency control will be described with reference to FIG. FIG. 16 is a flowchart illustrating an example of a flow of processing of sensor module adjustment and oscillation frequency control.
<Adjustment of sensor module>
In the oscillation control adjustment, after the module assembly process, the oscillation frequency of the angular velocity sensor module (angular velocity sensor unit 3) assembled in the process is measured and adjusted. The method of measuring the oscillation frequency of the angular velocity sensor module is to vibrate the vibrating part 3a according to the operation (oscillation operation or self-excited oscillation operation) in each of the above-described sections T1, T2, T3 (see FIG. 7) and monitor in the stable oscillation section T2. Output signals from 1a and 1b are detected. The square wave oscillation period count value Nf output from the square wave generator 5b before adjustment and the control value dtSft of the phase shifter 6c are set to, for example, standard values (for example, average values of mass production results) (step S11), and oscillation control is performed. Adjustment is started (from step S13 to step S21).

<Oscillation frequency control>
The angular velocity sensor unit 3 having a relatively low Q value starts oscillating even if there is a frequency error. Therefore, if the rectangular wave oscillation cycle count value Nf output from the rectangular wave generator 5b and the control value dtSft of the phase shifter 6c are swept within the allowable frequency error range, the angular velocity sensor unit 3 oscillates under any condition. Start (oscillation start processing in step S13 following step S11). If the angular velocity sensor unit 3 starts oscillating to form an oscillation loop (state of the stable oscillation section T2), the angular velocity sensor unit 3 is naturally drawn into the oscillation frequency of the angular velocity sensor unit 3, and the angular velocity sensor unit 3 maintains the state of stable oscillation to some extent. (Self-excited oscillation process in step S13). Therefore, the oscillation speed of the angular velocity sensor unit 3 is measured by measuring the count value Nf of the oscillation period and the count value Nsft of the phase shift amount of the angular velocity sensor unit 3 in the stable oscillation state (step S15 after step S13). Know the exact frequency. The phase shift adjustment of the phase shifter 6c requires a target value for the oscillation frequency when adjusting the silicon device. Therefore, the angular velocity sensor unit 3 can be adjusted for each period, and the oscillation frequency of the angular velocity sensor unit 3 can be adjusted. Retraction is fast.

It is also possible to measure the amplitude AQ of the carrier wave Vs output from the carrier wave generation circuit 6b (step S15), and when the amplitude AQ becomes larger than the specified value Vs_min (Yes in step S17 following step S15), the angular velocity sensor. It is determined that the oscillation of the unit 3 has been successful, the oscillation of the angular velocity sensor unit 3 is stopped (step S19 after Yes in step S17), the oscillation frequency control process is terminated, and the process proceeds to the next stage.
On the other hand, when the amplitude AQ is smaller than the specified value Vs_min (No in step S17), the count value Nf and the control value dtSft are changed (step S21 next to No in step S17), the process returns to step S13, and again, The sensor module adjustment process is started.

Here, step S13 corresponds to an example of a signal output step. Step S15 corresponds to an example of a signal detection step. Step S17 corresponds to an example of a signal comparison step. Step S19 and step S21 each correspond to an example of a signal adjustment step. Note that not changing the count value Nf and the control value dtSft is a kind of adjustment of the amplitude (an example of the first amplitude) and the time (an example of the first time) of the rectangular wave drive signal, and thus the step S19 is also a signal. This corresponds to the adjustment step.
FIG. 17 is a flowchart showing another example of the processing flow of oscillation amplitude control of the sensor module and oscillation control during normal operation.

First, in step S11, the count value Nf of the rectangular wave oscillation period and the control value dtSft of the phase shifter 6c are set by the same processing as in step S11 shown in FIG. 16, and the process proceeds to step S53.
Next, in step S53, a control value dtRct for controlling the amplitude of the rectangular wave driving voltage Vrct and a master clock count value Nup that is a count value of the master clock MCLK in the rectangular wave driving time Tup are set. The process proceeds to S55.
Thereafter, in step S55, the angular velocity sensor unit 3 starts oscillating and self-oscillates similarly to the processing in step S13 shown in FIG. 16, and then in step S57, the amplitude AQ is measured, and the process proceeds to step S59.

Here, the measurement of the carrier wave Vs by the monitor 1a has a plurality of occasions in the stable oscillation section T2, and the measurement value of the amplitude AQ in the first adjustment determination section and the last adjustment determination section is an adjustment procedure. You will need it.
In the control of this example, the measurement opportunity is assumed to be four times, the measurement value in the first adjustment determination section is the amplitude AQ (1), and the measurement value in the fourth (last) adjustment determination section is the amplitude AQ (2). The target value is assumed to be amplitude AQ (cw). Using these measured values, at least one of the signal amplitude of the rectangular wave drive voltage Vrct output from the rectangular wave generator 5b and the gain of the variable amplifier 6d is controlled, and adjustment is performed by incrementing data at the next oscillation.

If it is determined in step S59 that the measured amplitude AQ (1) or amplitude AQ (2) is smaller than the predetermined threshold VT (No), the process proceeds to step S71.
In step S71, it is determined that the frequency of the rectangular wave is greatly deviated from the resonance frequency, the oscillation is stopped, and the process proceeds to step S73.
In step S73, the rectangular wave oscillation cycle count value Nf set in step S51 and the control value DtSft of the phase shifter 6c are reset, and the process returns to step S53. Based on the reset count value Nft and the control value DtSft, the processes after step S53 are executed again.

On the other hand, in step S59, when the measured amplitude AQ (1) or amplitude AQ (2) is equal to or greater than the predetermined threshold VT (Yes), it is determined that the frequency of the rectangular wave is a setting close to the resonance frequency, and step S61. Migrate to The determination process in step S59 is “amplitude AQ (1) (or amplitude AQ (2)) − amplitude AQ (cw)”, that is, amplitude AQ (1) (or amplitude AQ (2)) to amplitude AQ (cw). ) May be determined based on whether or not the value obtained by subtracting) is equal to or greater than a predetermined threshold. In step S59, an example is shown in which the measured amplitude (absolute value of the waveform amplitude) is compared with a predetermined threshold value VT. In addition, the measured waveform is between -VT and + VT. It is also possible to make a determination based on whether or not.

Next, in step S61, the gain control value dtA of the variable amplifier 6d is set, and the process proceeds to step S63.
In step S63, measurement of the amplitude AQ is started, and the process proceeds to step S65.
Next, the following determination is made in step S65 while measuring the amplitude AQ.
In step S65, if ΔAQ (n) (“= AQ (n) −AQ (n−1)”, n = 2 in this example) is smaller than −ΔVT or larger than + ΔVT, the self-oscillation loop It is determined that the gain is less than 1 or greater than 1 (No), and the process proceeds to step S75.
In step S75, the gain control value dtA of the variable amplifier 6d is changed, and the process returns to step S63. Based on the control value dtA after the change, the processing after step S63 is executed again.

More specifically, in step S65, it is determined that the gain of the variable amplifier 6d is large when the relationship of “AQ (2) −AQ (1)> + ΔVT” is satisfied (determination result “>” (FIG. 13 (a ))), The control value dtA of the variable amplifier 6d is controlled so that the gain decreases.
In step S65, it is determined that the gain of the variable amplifier 6d is small when the relationship of “AQ (2) −AQ (1) <− ΔVT” is satisfied (determination result “<” (see FIG. 14A)). )), The control value dtA of the variable amplifier 6d is controlled so as to increase the gain.
On the other hand, in step S65, when the relationship of “+ ΔVT ≧ AQ (2) −AQ (1) ≧ −ΔVT” is satisfied, it is determined that the gain of the variable amplifier 6d is appropriate (determination result “=” (FIG. 13 (See (b) and FIG. 14 (b))), the gain of the variable amplifier 6d is maintained, and the process proceeds to step S67.

In step S67, the oscillation is stopped and the process proceeds to step S69.
In step S69, adjustment values in the memory provided in the sequencer 5e, that is, the control value dtA of the variable amplifier 6d set at the present time, the count value Nf of the rectangular wave oscillation period, the control value dtSft of the phase shifter 6c, and the rectangular wave amplitude are set. The control value dtRct and the rectangular wave driving time Tup are written, and the adjustment of the oscillation amplitude control of the sensor module and the oscillation control during the normal operation are completed.
Here, step S55 corresponds to an example of a signal output step. Step S57 corresponds to an example of a signal detection step. Step S59 corresponds to an example of a signal comparison step. Step S73 corresponds to an example of a signal adjustment step.

<Oscillation during normal operation>
According to the adjustment flow, the oscillation control is relatively easy to adjust if the sensor oscillates. Therefore, it is also possible to store only the control value (count value) Nf of the oscillation frequency and obtain other control values within a certain interval. In particular, temperature drift is an effective means because it is only necessary to grasp the temperature characteristics of the oscillation frequency.
Also, drift can be followed during time-division operation. Since the oscillation frequency of the vibration unit varies depending on the temperature, it is difficult for the conventional circuit to make the oscillation frequency of the vibration unit follow the temperature drift, and it is difficult to stably oscillate the vibration unit. In addition, the conventional circuit requires some control circuit for temperature drift, and the circuit area increases. According to this embodiment, it becomes possible to follow the temperature drift.
As described above, since the oscillation control unit 5 includes the

monitors

1a and 1b, the rectangular wave oscillation period is calculated from the monitor values of the square wave oscillation period count value Nf, the phase shift amount count value Nsft, and the carrier wave Vs amplitude AQ. And the control value dtSft of the phase shifter 6c, the gain control value dtA of the variable amplifier 6d, the rectangular wave amplitude control value dtRct, and the control value Nup of the rectangular wave drive time can be updated. It is. That is, the energy of the vibration start signal applied to the drive electrode during the next vibration start section is adjusted based on the amplitude of the detection signal or the excitation signal in the angular velocity detection section or the fluctuation amount of the amplitude. For example, if the amplitude of the detection signal or excitation signal in the angular velocity detection section is larger than the reference value, and if the variation amount of the detection signal or excitation signal in the angular velocity detection section is larger than the reference value, the previous vibration starts Adjustment is made so that the energy of the vibration start signal applied to the drive electrode during the vibration start interval set later is smaller than the energy of the vibration start signal applied to the drive electrode during the interval. Also, if the amplitude of the detection signal or excitation signal in the angular velocity detection section is smaller than the reference value, and if the fluctuation amount of the detection signal or excitation signal in the angular velocity detection section is smaller than the reference value, the previous vibration starts Adjustment is made so that the energy of the vibration start signal applied to the drive electrode during the vibration start interval set later is larger than the energy of the vibration start signal applied to the drive electrode during the interval. The energy of the vibration start signal is adjusted by the amplitude of the vibration start signal and the time output to the drive electrode.

Specifically, description will be made with reference to FIG. A first Z-axis vibration start signal is output to the drive electrode in the first vibration start section of the Z-axis. The first Z-axis direction excitation signal generated based on the first Z-axis direction detection signal is output to the drive electrode in the first Z-axis angular velocity detection section. In this section, the amplitude of the output signal Via output to the carrier Vs corresponding to the detection signal or the driver corresponding to the excitation signal, or the amount of fluctuation of the amplitude is monitored by the

monitor

1a, 1b or the like. Note that monitoring may be performed in all sections of the angular velocity detection section, or may be performed in a partial section. After the end of monitoring, the amplitude or time of the second vibration start signal in the next vibration start section is determined. A signal obtained by inverting the first Z-axis direction excitation signal based on the first Z-axis direction detection signal is output to the drive electrode during the first oscillation stop period of the Z-axis.

Next, the X axis is driven in the same manner as the Z axis. A first X-axis direction vibration start signal is output to the drive electrode in the first X-axis vibration start section. The first Z-axis direction excitation signal generated based on the first X-axis direction detection signal is output to the drive electrode in the first X-axis angular velocity detection section. In this section, the amplitude of the output signal Via output to the carrier Vs corresponding to the detection signal or the driver corresponding to the excitation signal, or the amount of fluctuation of the amplitude is monitored by the

monitor

1a, 1b or the like. Note that monitoring may be performed in all sections of the angular velocity detection section, or may be performed in a partial section. In the first oscillation stop period of the X axis, a signal obtained by inverting the first X axis direction excitation signal based on the first X axis direction detection signal is output to the drive electrode.

Next, the Z-axis direction vibration is started by the second Z-axis direction vibration start signal having the updated amplitude or time. For example, the sequencer controls the amplitude of the rectangular wave generator and the time at which the vibration start signal is output based on the updated amplitude information or time information. A second Z-axis vibration start signal is output to the drive electrode in the second vibration start section of the Z-axis. A second Z-axis direction excitation signal generated based on the second Z-axis direction detection signal is output to the drive electrode in the second Z-axis angular velocity detection section. In this section, the monitor and the amplitude or time may be determined as before. A signal obtained by inverting the second Z-axis direction excitation signal based on the second Z-axis direction detection signal is output to the drive electrode during the second oscillation stop period of the Z-axis.

Next, the vibration in the X-axis direction is started by the second X-axis direction vibration start signal having the updated amplitude or time. For example, the sequencer controls the amplitude of the rectangular wave generator and the time at which the vibration start signal is output based on the updated amplitude information or time information. A second X-axis direction vibration start signal is output to the drive electrode in the second X-axis vibration start section. A second Z-axis direction excitation signal generated based on the second X-axis direction detection signal is output to the drive electrode in the second X-axis angular velocity detection section. In this section, the monitor and the amplitude or time may be determined as before. A signal obtained by inverting the second X-axis direction excitation signal based on the second X-axis direction detection signal is output to the drive electrode during the second oscillation stop period of the X-axis. The amplitude or time of the vibration start signal on each axis may be updated every interval, every few intervals, or only one of the axes.

For the monitoring of the count value Nf of the rectangular wave oscillation period, the count value Nsft of the phase shift amount, and the amplitude AQ of the carrier wave Vs, it is sufficient to measure a part of the self-excited oscillation period. Since the temperature change is relatively slow, it is possible to thin out the time division measurement from the viewpoint of reducing power consumption. It is also possible to install a thermometer in the silicon device, and it is also effective to perform monitor measurement when the temperature changes to some extent.

<Phase shifter>
FIG. 18 is a diagram illustrating a circuit configuration and frequency characteristics of the phase shifter 6c. 18A shows the circuit configuration of the phase shifter 6c, and FIG. 18B shows the frequency characteristics of the phase shifter 6c. In FIG. 18B, the horizontal axis indicates the frequency (Hz), and the vertical axis indicates the phase (°).
As shown in FIG. 18A, the phase shifter 6c has an all-pass filter circuit 161. The all-pass filter circuit 161 includes an amplifier 161a, a resistor element 161b, a capacitor element 161c, an input resistor 161d, and a feedback resistor 161e. One terminal of the input resistor 161d is connected to the output terminal of the carrier wave generating circuit 6b (not shown in FIG. 18A) and one terminal of the resistor element 161b, and the other terminal is connected to the inverting input terminal (−) of the amplifier 161a and the feedback resistor. 161e is connected to one terminal. The other terminal of the feedback resistor 161e is connected to the output terminal of the amplifier 161a and the input terminal of the variable amplifier 6d (not shown in FIG. 18A), and one terminal is also connected to the inverting input terminal (−) of the amplifier 161a. ing. The other terminal of the resistive element 161b is connected to the non-inverting input terminal (+) of the amplifier 161a and one electrode of the capacitive element 161c. The other electrode of the capacitive element 161c is connected to the input terminal of the operating common voltage VCOM, and one electrode is also connected to the non-inverting input terminal (+) of the amplifier 161a. The output terminal of the amplifier 161a is the output terminal of the phase shifter 6c, and is connected to the input terminal of the variable amplifier 6d (not shown in FIG. 18A). Assuming that the resistance value of the resistance element 161b is R and the capacitance value of the capacitance element 161c is C, the all-pass filter circuit 161 is phase-shifted by 90 ° at f = 1 / (2πRC) as shown in FIG. The phase shifter 6c makes at least one of the resistance value R of the resistance element 161b and the capacitance value C of the capacitance element 161c variable, and the phase shifter 6c outputs an output signal that is 90 ° phase shifted with respect to the input signal. The frequency is adjusted.

<Rectangular wave generator>
A schematic configuration and an operation timing chart of the rectangular wave generator 5b will be described with reference to FIGS. FIG. 19 is a circuit block showing an example of a schematic configuration of the rectangular wave generator 5b. As shown in FIG. 19, the rectangular wave generator 5b includes a variable voltage source (VR_RCT) 51a, an amplifier (OP_U) 51b, an amplifier (OP_D) 51c,

switches

51d, 51e, 51f, 51g, 51h, and 51i. And a switch control unit 51j.

A reference voltage VREF, an operation common voltage VCOM, and a rectangular wave amplitude control value drRct are input to the variable voltage source 51a. The variable voltage source 51a outputs a high level voltage VrctH and a low level voltage VrctL whose voltage values are adjusted based on the rectangular wave amplitude control value dtRct, and an operation common voltage VCOM. The high level voltage VrctH and the low level voltage VrctL of the rectangular wave output drive voltage Vrct output from the rectangular wave generator 5b are as follows.
VrctH = VCOM + Vrct / 2
VrctL = VCOM−Vrct / 2
The amplifier 51b and the amplifier 51c function as, for example, a voltage follower circuit. The amplifier 51b outputs an output signal having the same potential as the input high level voltage VrctH. The amplifier 51c outputs an output signal having the same potential as the input low level voltage VrctL.

When the switch 51d is turned on, the output terminal of the amplifier 51b is connected to one output terminal of the rectangular wave generator 5b. When the switch 51e is turned on, the output terminal of the amplifier 51b is connected to the other output terminal of the rectangular wave generator 5b. One output terminal of the rectangular wave generator 5b is a terminal that outputs a rectangular wave drive signal Rct1, and the other output terminal is a terminal that outputs a rectangular wave drive signal Rct2. When the switch 51 f is turned on, the variable voltage source 51 a connects an output terminal (hereinafter referred to as “common voltage output terminal”) from which the operating common voltage VCOM is output to one output terminal of the rectangular wave generator 5 b. When the switch 51g is turned on, the variable voltage source 51a connects the common voltage output terminal to the other output terminal of the rectangular wave generator 5b. When the switch 51h is turned on, the output terminal of the amplifier 51c is connected to one output terminal of the rectangular wave generator 5b. When the switch 51i is turned on, the output terminal of the amplifier 51c is connected to the other output terminal of the rectangular wave generator 5b.

The switch control unit 51j controls the on state and the off state (ON / OFF) of the switches 51d to 51i. Each signal of the master clock MCLK, the oscillation start state control signal E_RCT, the count value Nf, and the rectangular wave driving time Nup is input to the switch control unit 51j. The switch control unit 51j outputs control signals D1P, D2P, D1N, D2N, and D0 for controlling the switches 51d to 51i based on the signal levels of the input signals. When the signal levels of the control signals D1P, D2P, D0, D1N, and D2N become high, the switches 51d to 51i are turned on, for example, and when the signal levels of the control signals D1P, D2P, D0, D1N, and D2N become low. The switches 51d to 51i are turned off, for example.

When the switching circuit 5c (not shown in FIG. 19) is switched to the rectangular wave generator 5b side and the switch 51d is turned on, the output terminal of the amplifier 51b and the drive electrode D1 (not shown in FIG. 19) are connected. 51b charges the drive electrode D1 with a rectangular wave drive signal Rct1 having the same voltage level as the high level voltage VrctH.
When the switching circuit 5c (not shown in FIG. 19) is switched to the rectangular wave generator 5b side and the switch 51e is turned on, the output terminal of the amplifier 51b and the drive electrode D2 (not shown in FIG. 19) are connected. 51b charges the drive electrode D2 with a rectangular wave drive signal Rct2 having the same voltage level as the high level voltage VrctH.

When the switching circuit 5c (not shown in FIG. 19) is switched to the rectangular wave generator 5b side and the switch 51h is turned on, the output terminal of the amplifier 51c and the drive electrode D1 are connected, and the amplifier 51c has the low level voltage VrctL. A rectangular wave drive signal Rct1 having a voltage level of the same potential as that of the drive electrode D1 is charged.
When the switching circuit 5c (not shown in FIG. 19) is switched to the rectangular wave generator 5b side and the switch 51i is turned on, the output terminal of the amplifier 51c and the drive electrode D2 are connected, and the amplifier 51c has the low level voltage VrctL. A rectangular wave drive signal Rct2 having a voltage level of the same potential as that of the drive electrode D2 is charged.

When the switching circuit 5c (not shown in FIG. 19) is switched to the rectangular wave generator 5b side and the switch 51f is turned on, the common voltage output terminal and the drive electrode D1 are connected, and the variable voltage source 51a An output signal having a voltage level equal to that of VCOM is charged to the drive electrode D1.
When the switching circuit 5c (not shown in FIG. 19) is switched to the rectangular wave generator 5b side and the switch 51g is turned on, the common voltage output terminal and the drive electrode D2 are connected, and the variable voltage source 51a An output signal having the same voltage level as that of VCOM is charged to the drive electrode D2. Both the switch 51f and the switch 51g are controlled based on the control signal D0 and are simultaneously turned on. Therefore, the drive electrode D1 and the drive electrode D2 are simultaneously charged with a voltage having the same potential as the operation common voltage VCOM.
As described above, the rectangular wave generator 5b is a tristate buffer that outputs the operation common voltage VCOM, the high level voltage VrctH, and the low level voltage VrctL.

The operation of the rectangular wave generator 5b in the oscillation start section T1 in Z-Drive will be described with reference to FIGS. 1 and 19 and FIG. FIG. 20 shows an example of an operation timing chart of the rectangular wave generator 5b in the oscillation start section T1 in Z-Drive. In FIG. 20, “E_RCT” in the first stage indicates the signal waveform of the oscillation start state control signal E_RCT, and “D1P, D2P” in the second stage indicates the signal waveforms of the control signal D1P and the control signal D2P. The third stage “D1N, D2N” indicates the signal waveforms of the control signal D1N and the control signal D2N, the fourth stage “D0” indicates the signal waveform of the control signal D0, and the fifth stage “Vdr” The voltage waveform of the drive voltage input into the drive electrodes D1 and D2 is shown. In the figure, the horizontal axis indicates time, and the passage of time is represented from left to right in the figure.

As shown in FIG. 20, the oscillation start state control signal E_RCT is a signal that controls whether or not the angular velocity sensor unit 3 is in the state of the oscillation start section T1. If the signal level of the oscillation start state control signal E_RCT is high, an oscillation start interval (in this example, “T1” interval) is entered, and the rectangular wave generator 5b operates.
In the section represented by “T1-Nup / fclk” from the start of the operation of the rectangular wave generator 5b, the signal level of the control signal D0 becomes high as shown in the fourth stage of FIG. 19, and the

switch

51f , 51g are turned on. On the other hand, in the section, as shown in the second and third stages in FIG. 20, the signal levels of the control signals D1P, D2P, D1N, D2N are low and the

switches

51d, 51e, 51h, 51i are in the off state. It becomes. Therefore, in the section, as shown in the fifth stage in the figure, the drive electrodes D1 and D2 are connected to the common voltage output terminal. Thereby, the operation common voltage VCOM is applied to the drive electrodes D1 and D2 as the oscillation control unit output signal Vdr.

In the subsequent section represented by “Nup / fclk”, as shown in the third row in FIG. 20, the signal level of the control signal D0 becomes low and the

switches

51f and 51g are turned off. On the other hand, in the section, as shown in the second and third stages in FIG. 20, the control signals D1P and D2P are rectangular wave signals having one cycle of “Nf / fclk”. The control signals D1N and D2N are rectangular wave signals having a cycle of “Nf / fclk” and having a phase inverted by 180 ° from the control signals D1P and D2P. For this reason, in the section, the

switches

51h and 51i are turned off when the

switches

51d and 51e are on, and the

switches

51h and 51i are turned on when the

switches

51d and 51e are off. As a result, as shown in the fifth stage in FIG. 20, the oscillation control unit output signal Vdr has a center voltage value of the operation common voltage VCOM and a high level voltage value of the high level voltage VrctH. The low-level voltage value is the low-level voltage VrctL, and a rectangular voltage waveform having one cycle of “Nf / fclk” is obtained. The amplitude voltage of the oscillation control unit output signal Vdr is a value obtained by adding the absolute value of the low level voltage VrctL to the absolute value of the high level voltage VrctH. In this example, since the absolute value of the high level voltage VrctH is equal to the absolute value Vrct of the low level voltage VrctL, the amplitude voltage of the oscillation control unit output signal Vdr is 2 of the voltage value of the high level voltage VrctH or the low level voltage VrctL. Doubled.

The control signal D1P and the control signal D2P are the same signal, the control signal D1N and the control signal D2N are the same signal, and the output signals of the oscillation control units that drive the drive electrodes D1 and D2 are the same during Z-Drive.
When the oscillation start period T1 ends, the stable oscillation period T2 starts. As shown in the first stage of FIG. 20, in the stable oscillation period T2, the oscillation start state control signal E_RCT is a low level signal, and is not in the state of the oscillation start period T1. Therefore, as shown in the second to fourth stages in FIG. 20, the switch control unit 51j outputs control signals D1P, D2P, D1N, D2N, and D0 having low signal levels. Thereby, the variable voltage source 51a is electrically disconnected from the drive electrodes D1 and D2. Further, in synchronization with the oscillation start state control signal E_RCT becoming a low level signal, the switching circuit 5c connects the drive electrodes D1 and D2 and the driver 6e. As a result, as shown in the fifth row in FIG. 20, a self-excited oscillation signal Dr1 based on the self-excited oscillation of the angular velocity sensor unit 3 is applied to the drive electrodes D1 and D2 as the oscillation control unit output signal Vdr.

The operation of the rectangular wave generator 5b in the oscillation start period T1 in X-Drive will be described with reference to FIGS. 1 and 19 and FIG. FIG. 21 shows an example of an operation timing chart of the rectangular wave generator 5b in the oscillation start section T1 in X-Drive. In FIG. 21, the first stage “E_RCT” indicates the signal waveform of the oscillation start state control signal E_RCT, and the second stage “D1P, D2N” indicates the signal waveforms of the control signal D1P and the control signal D2N. “D1N, D2P” in the third stage shows signal waveforms of the control signal D1N and the control signal D2P, “D0” in the fourth stage shows a signal waveform of the control signal D0, and “Vdr” in the fifth stage in the figure. "Indicates the voltage waveform of the oscillation control unit output signal input to the drive electrode D1, and" -Vdr "in the sixth stage in the figure indicates the voltage waveform of the oscillation control unit output signal input to the drive electrode D2. Yes. In the figure, the horizontal axis indicates time, and the passage of time is represented from left to right in the figure.

As shown in the second and third stages in FIG. 21, in the X-Drive, unlike the Z-Drive, the control signal D1P and the control signal D2N are the same signal, and the control signal D1N and the control signal D2P are The control signal D1P and the control signal D2N are the same signal, and the phase is inverted by 180 °. Therefore, when the signal levels of the control signal D1P and the control signal D2N are high and the signal levels of the control signal D1P and the control signal D2N are low as shown in the fifth and sixth stages in FIG. In addition, a drive signal Vdr having a high level voltage VrctH is applied to the drive electrode D1, and a drive signal −Vdr having a low level voltage VrctL is applied to the drive electrode D2. On the other hand, when the signal levels of the control signal D1P and the control signal D2N are low and the signal levels of the control signal D1N and the control signal D2P are high, the drive electrode D1 is a drive signal having a low level voltage VrctL. Vdr is applied, and a drive signal −Vdr having a high level voltage VrctH is applied to the drive electrode D2.
As described above, in the case of X-Drive, the count value Nf and the control value Nup are different from those in the case of Z-Drive, and the drive signals Vdr and -Vdr having opposite phases are applied to the drive electrode D1 and the drive electrode D2. The
Further, in any case of Z-Drive and X-Drive, the oscillation start operation need not be synchronized with the carrier wave.

<Sensor drive unit>
Next, schematic configurations of the driver 6e and the switching circuit 5c will be described with reference to FIGS. FIG. 22 is a circuit block diagram illustrating an example of a schematic configuration of the driver 6e and the switching circuit 5c. In FIG. 22, the rectangular wave generator 5 b is also illustrated for easy understanding.
As shown in FIG. 22, the driver 6e includes

amplifiers

61a and 62b,

feedback resistors

61b and 62b,

input resistors

61c and 62c,

switches

63a, 63b, 63c and 63d, and

switches

64a, 64b, 64c and 64d. , And switches 65 and 66.

A feedback resistor 61b and a switch 64b connected in parallel are connected between the output terminal of the amplifier 61a and the inverting input terminal (−). A switch 63a and an input resistor 61c connected in series are connected between the inverting input terminal (−) of the amplifier 61a and the input terminal of the driver 6e connected to the output terminal of the variable amplifier 6d (see FIG. 2). Has been. The switch 63a is provided on the input terminal side of the driver 6e, and the input resistor 61c is provided on the amplifier 61a side. A switch 64a is connected between the non-inverting input terminal (+) of the amplifier 61a and the input terminal of the driver 6e. A switch 63b is connected between the non-inverting input terminal and the switch 64a and between the input terminal of the operation common voltage VCOM. An output terminal of the amplifier 61a is connected to an input terminal of a switch 52a (details will be described later) provided in the switching circuit 5c.

A feedback resistor 62b and a switch 64d connected in parallel are connected between the output terminal of the amplifier 62a and the inverting input terminal (−). A series-connected switch 66, switch 63c, and input resistor 62c are connected between the inverting input terminal (−) of the amplifier 62a and the input terminal of the driver 6e connected to the output terminal of the variable amplifier 6d. Yes.

Switches

66 and 63c are provided on the input terminal side of the driver 6e, and an input resistor 62c is provided on the amplifier 62a side. A switch 65 and a switch 64c connected in series are connected between the non-inverting input terminal (+) of the amplifier 61a and the input terminal of the driver 6e. A switch 63d is connected between the non-inverting input terminal (+) and the switch 64c and between the input terminal of the operation common voltage VCOM. An output terminal of the amplifier 62a is connected to an input terminal of a switch 52b (details will be described later) provided in the switching circuit 5c.

The

switches

63a, 63b, 63c, and 63d are controlled to be opened / closed based on a control signal LP180 input to these control signal input terminals, and are simultaneously closed (on) or open (off). The control signal input terminal is, for example, a positive logic input.
The

switches

64a, 64b, 64c, and 64d are controlled to open and close based on a control signal LP360 input to a control signal input terminal, and are simultaneously closed (on) or open (off). The control signal input terminal is the same logic input as the control signal input terminals of the

switches

63a, 63b, 63c, and 63d, for example, a positive logic input.

The control signal LP180 and the control signal LP360 are opposite phase signals. Therefore, when the

switches

63a, 63b, 63c, and 63d are turned on, the

switches

64a, 64b, 64c, and 64d are turned off, and when the

switches

63a, 63b, 63c, and 63d are turned off, the

switches

64a, 64b, 64c and 64d are turned on. Details will be described with reference to FIGS. 23 to 28. When the

switches

63a, 63b, 63c, and 63d are turned on and the

switches

64a, 64b, 64c, and 64d are turned off, the driver 6e Functions as an inverting amplifier circuit. When each of the

switches

63a, 63b, 63c, and 63d is turned off and each of the

switches

64a, 64b, 64c, and 64d is turned on, the driver 6e functions as a voltage follower circuit.

The switch 65 is connected between the input terminal of the switch 63a and the input terminal of the switch 64c, and the open / close state is controlled based on the control signal ZD input to the control signal input terminal. The control input terminal is, for example, a positive logic input. The switch 65 and a switch 54 described later are turned on when the oscillation control unit 5 functions as Z-Drive, and are turned off when the oscillation control unit 5 functions as X-Drive.
The switch 66 is connected between the input terminal of the switch 64a and the input terminal of the switch 63c, and the open / close state is controlled based on the control signal XD input to the control signal input terminal. The control input terminal is, for example, a positive logic input. The switch 66 is turned off when the oscillation control unit 5 functions as Z-Drive, and is turned on when the oscillation control unit 5 functions as X-Drive.

The switching circuit 5c includes

switches

52a and 52b,

switches

53a and 53b, and a switch 54.
The switch 52a is connected between the output terminal of the amplifier 61a of the driver 6e and the drive electrode D1. The output terminal of the switch 52a is connected to the drive electrode D1. The switch 52b is connected between the output terminal of the amplifier 62a of the driver 6e and the drive electrode D2. The output terminal of the switch 52b is connected to the drive electrode D2. The switch 52a and the switch 52b are controlled to be opened / closed based on a control signal FB input to a control signal input terminal. The control input terminal is, for example, a positive logic input.

The switch 53a is connected between the output terminals (see FIG. 19) of the

switches

51d, 51f, and 51h of the rectangular wave generator 5b and the drive electrode D1 (see FIG. 2). The switch 53b is connected between the output terminals (see FIG. 19) of the

switches

51e, 51g, and 51i of the rectangular wave generator 5b and the drive electrode D2 (see FIG. 2). The switch 53a and the switch 53b are controlled to open and close based on a control signal RCT input to the control signal input terminal, and are simultaneously in a closed state (on state) or an open state (off state). The control input terminal is, for example, a positive logic input.

The control signal RCT and the control signal FB are, for example, signals having opposite phases. Therefore, when the

switches

53a and 53b are turned on, the

switches

52a and 52b are turned off, and when the

switches

53a and 53b are turned off, the

switches

52a and 52b are turned on. In the oscillation start period T1, the

switches

53a and 53b are turned on and the rectangular wave generator 5b is connected to the drive electrodes D1 and D2, whereas the

switches

52a and 52b are turned off and the driver 6e is driven. It is electrically disconnected from D1 and D2. In the stable oscillation period T2 and the oscillation stop period T3, the

switches

53a and 53b are turned off and the rectangular wave generator 5b is electrically disconnected from the drive electrodes D1 and D2, whereas the

switches

52a and 52b are turned on. In this state, the driver 6e is connected to the drive electrodes D1 and D2.

Next, the connection relationship of the driver 6e, the rectangular wave generator 5b and the switching circuit 5c in Z-Drive and the operation of the angular velocity sensor 1 will be described with reference to FIGS. 23 to 28 with reference to FIGS. FIG. 23 is a diagram illustrating a schematic configuration of a connection state of the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the oscillation start section T1 in Z-Drive. FIG. 24 is a diagram showing a schematic configuration of a connection state of the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the stable oscillation section T2 in Z-Drive. FIG. 25 is a diagram illustrating a schematic configuration of a connection state of the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the oscillation stop period T3 in Z-Drive. In FIGS. 23 to 25 and FIGS. 26 to 28 described later, the

switches

52a, 52b, 53a, 53b, 54, 63a to 63d, 64a to 64d, 65 and 66 are shown as straight lines in the on state. In the off state, the illustration is omitted. Also, in FIGS. 23 to 25 and FIGS. 26 to 28 to be described later, illustration of resistors and wirings that are electrically disconnected from the driver 6e, the rectangular wave generator 5b, or the switching circuit 5c when the switch is turned off is omitted. Has been.

In the oscillation start period T1 in Z-Drive, the signal level of the control signal RCT is high, the signal level of the control signal FB is low, the signal level of the control signal LP360 of the switches 64a to 64d is high, and the switch 63a The signal level of the control signal LP180 of .about.63d becomes a low level state. As a result, as shown in FIGS. 22 and 23, in the oscillation start section T1 in Z-Drive, the

switches

53a and 53b are turned on and the

switches

52a and 52b are turned off, so that the rectangular wave generator 5b and the drive are driven. The electrodes D1 and D2 are connected, and the driver 6e is disconnected from the drive electrodes D1 and D2. Further, the switch 54 is turned on, the two output terminals of the rectangular wave generator 5b are connected, and the drive electrodes D1, D2 are also connected.

The switches 63a to 63d are turned off, and the switches 64a to 64d are turned on. Therefore, the output terminal of the amplifier 61a and the inverting input terminal (−) are connected via the switch 64b, the input resistor 61c is disconnected from the input terminal of the driver 6e by the switch 63a, and the non-inverting input terminal (+) of the amplifier 61a. And the input terminal of the driver 6e are connected via a switch 64a. The output terminal of the amplifier 62a and the inverting input terminal (−) are connected via the switch 64d, the input resistor 61c is disconnected from the input terminal of the driver 6e by the switch 63a, and the non-inverting input terminal (+) of the amplifier 62a. The input terminal of the driver 6e is connected via the switch 64c. Accordingly, the driver 6e functions as a voltage follower, and the same signal as the input signal input from the input terminal of the driver 6e (that is, the output signal output from the variable amplifier 6d (see FIG. 2)) is used as the self-excited oscillation signals Dr1 and Dr2. Output from the output terminals of the

amplifiers

61a and 62a.

The switching circuit 5c selects the rectangular wave generator 5b from the rectangular wave generator 5b and the driver 6e in the oscillation start period T1 during Z-Drive, and the rectangular wave rectangular wave drive signal Rct1 generated by the rectangular wave generator 5b. , Rct2 are output to the drive electrodes D1, D2. Therefore, the rectangular wave drive signal Rct1 generated by the rectangular wave generator 5b is input to the drive electrodes D1 and D2 as the oscillation control unit output signals Vdr and Vdr via the switching circuit 5c. As described with reference to FIG. 20, in the oscillation start period T1 at the time of Z-Drive, the rectangular wave drive signal Rct1 and the rectangular wave drive signal Rct2 are the same signal, and therefore, two output terminals of the rectangular wave generator 5b. There is no problem even if is connected.

When the self-excited oscillation signals Dr1 and Dr2 are input to the drive electrodes D1 and D2 as the oscillation control unit output signal Vdr, the vibration unit 3a shown in FIG. 2 starts to vibrate at the frequency of the self-excited oscillation signals Dr1 and Dr2. Then, it vibrates at the oscillation frequency of the angular velocity sensor unit 3 while increasing the vibration amplitude. Thereby, the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 are detected from the detection electrodes X1, X2, Y1, and Y2. Based on detection of the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 from the detection electrodes X1, X2, Y1, and Y2, the carrier wave generation circuit 6b outputs the carrier wave Vs, and the phase shifter 6c outputs the output signal Vi. An output signal Via is output from the variable amplifier 6d. The phase of the output signal Vi is shifted by 90 ° with respect to the phase of the carrier wave Vs. Since the driver 6e functions as a voltage follower circuit, the self-excited oscillation signals Dr1 and Dr2 output from the driver 6e have the same signal waveform as the output signal Via.

In the stable oscillation section T2 in Z-Drive, the signal level of the control signal RCT is low, the signal level of the control signal FB is high, the signal level of the control signal LP360 of the switches 64a to 64d is high, and the switch 63a The signal level of the control signal LP180 of .about.63d becomes a low level state. Accordingly, as shown in FIGS. 22 and 23, in the stable oscillation section T2 in Z-Drive, the

switches

52a and 52b are turned on and the

switches

53a and 53b are turned off. Therefore, as shown in FIG. Driver 6e and drive electrodes D1, D2 are connected, and rectangular wave generator 5b is disconnected from drive electrodes D1, D2. Further, the switch 54 is turned on, the two output terminals of the rectangular wave generator 5b are connected, and the drive electrodes D1, D2 are also connected.

Since the open / close state of the switches 63a to 63d and the switches 64a to 64d in the stable oscillation section T2 in Z-Drive is the same as the open / close state in the oscillation start section T1 in Z-Drive, the driver 6e functions as a voltage follower. The same signal as the input signal input from the input terminal of the driver 6e (that is, the output signal output from the variable amplifier 6d (see FIG. 4)) is output from the output terminals of the

amplifiers

61a and 62a as the self-excited oscillation signals Dr1 and Dr2.

In the stable oscillation section T2 during Z-Drive, the switching circuit 5c selects the driver 6e from the rectangular wave generator 5b and the driver 6e and outputs the self-excited oscillation signals Dr1 and Dr2 output by the driver 6e to the oscillation control unit output. The signal Vdr is output to the drive electrodes D1 and D2. When the switching circuit 5c selects the driver 6e, a 360 ° oscillation loop is formed in the self-excited oscillation circuit 5a, and the angular velocity sensor 1 starts and continues self-excited oscillation based on the oscillation frequency of the angular velocity sensor unit 3. As a result, the self-excited oscillation signals Dr1 and Dr2 output from the driver 6e and based on the self-excited oscillation of the angular velocity sensor unit 3 are input to the drive electrodes D1 and D2 as the output signal Vdr via the switching circuit 5c. In the stable oscillation section T2 at the time of Z-Drive, since the self-excited oscillation signal Dr1 and the self-excited oscillation signal Dr2 are the same signal, the output terminal of the amplifier 61a and the output terminal of the amplifier 62a are connected via the switch 54. No problem.

In the stable oscillation section T2 during Z-Drive, the angular velocity sensor unit 3 continues self-excited oscillation, so that the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 are detected from the detection electrodes X1, X2, Y1, and Y2. Based on the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 detected from the detection electrodes X1, X2, Y1, and Y2, the carrier wave Vs is output from the carrier wave generation circuit 6b, and the output signal Vi is output from the phase shifter 6c and is variable. An output signal Via is output from the amplifier 6d. The phase of the output signal Vi is shifted by 90 ° with respect to the phase of the carrier wave Vs. Since the driver 6e functions as a voltage follower circuit, the self-excited oscillation signals Dr1 and Dr2 output from the driver 6e have the same signal waveform as the output signal Via.

Further, in the stable oscillation section T2 during Z-Drive, the rectangular wave generator 5b is in a power-down state (non-operating state). For this reason, the rectangular wave drive signals Rct1 and Rct2 are not output from the rectangular wave generator 5b.
In the oscillation stop period T3 in Z-Drive, the signal level of the control signal RCT is low, the signal level of the control signal FB is high, the signal level of the control signal LP360 of the switches 64a to 64d is low, and the switch 63a The signal level of the control signal LP180 of .about.63d becomes a high level state. Accordingly, as shown in FIGS. 22 and 24, in the oscillation stop period T3 in Z-Drive, the

switches

52a and 52b are turned on and the

switches

53a and 53b are turned off, so that the driver 6e and the drive electrodes D1, D2 is connected, and the rectangular wave generator 5b is disconnected from the drive electrodes D1 and D2. Further, the switch 54 is turned on, the two output terminals of the rectangular wave generator 5b are connected, and the drive electrodes D1, D2 are also connected.

The switches 63a to 63d are turned on, and the switches 64a to 64d are turned off. Therefore, the output terminal of the amplifier 61a and the inverting input terminal (−) are connected via the feedback resistor 61b, and the non-inverting input terminal (+) of the amplifier 61a and the input terminal of the operating common voltage VCOM are connected via the switch 63b. Connected. The inverting input terminal (−) is connected to the input terminal of the driver 6e via the input resistor 61c and the switch 63a. The output terminal of the amplifier 62a and the inverting input terminal (−) are connected via the feedback resistor 62b, and the non-inverting input terminal (+) of the amplifier 62a and the input terminal of the operating common voltage VCOM are connected via the switch 63d. Connected. Further, the inverting input terminal (−) is connected to the input terminal of the driver 6e through the input resistor 62c and the switch 63c.
Here, when the resistance values of the

feedback resistors

61b and 62b are R and the resistance values of the

input resistors

61c and 62c are r, the driver 6e functions as an inverting amplifier circuit having an inverting amplification factor of “R / r”. .

The switching circuit 5c selects the self-excited oscillation signals Dr1 and Dr2 output from the driver 6e by selecting the driver 6e from the rectangular wave generator 5b and the driver 6e in the oscillation stop period T3 during Z-Drive. Output to D2. When the oscillation control unit 5 selects the driver 6e that functions as an inverting amplifier circuit, a 180 ° stable loop is formed in the self-excited oscillation circuit 5a. Therefore, the self-excited oscillation signals Dr1 and Dr2 output from the driver 6e are signals whose phases are inverted by 180 ° with respect to the self-excited oscillation signals Dr1 and Dr2 in the stable oscillation period T2. In the oscillation stop period T3, since the 180 ° stable loop is formed in the angular velocity sensor unit 3 and the self-excited oscillation circuit 5c, the amplitude of the self-excited oscillation based on the oscillation frequency of the angular velocity sensor unit 3 gradually decreases. Self-excited oscillation stops. The self-oscillation signals Dr1 and Dr2 output from the driver 6e are input to the drive electrodes D1 and D2 as the output signal Vdr through the switching circuit 5c. In the oscillation stop period T3 during Z-Drive, since the self-excited oscillation signal Dr1 and the self-excited oscillation signal Dr2 are the same signal, the output terminal of the amplifier 61a and the output terminal of the amplifier 62a are connected via the switch 54. No problem.

In the oscillation stop period T3 at the time of Z-Drive, the angular velocity sensor unit 3 stops self-excited oscillation, so that the amplitudes of the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 detected by the detection electrodes X1, X2, Y1, and Y2 are gradually increased. Decreases to zero. Thereby, as shown in the seventh to ninth stages in FIG. 27, the phases of the carrier Vs and the carrier Vs generated by the carrier generation circuit 6b based on the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 are 90 °. The respective amplitudes of the output signal Via output from the variable amplifier 6d that receives the output signal Vi of the shifted phase shifter 6c and the output signal Vi are also gradually reduced to zero.
In addition, in the oscillation stop period T3 during Z-Drive, the rectangular wave generator 5b is in a power-down state (non-operating state). For this reason, the rectangular wave drive signals Rct1 and Rct2 are not output from the rectangular wave generator 5b.

Next, the connection relationship between the driver 6e, the rectangular wave generator 5b and the switching circuit 5c in X-Drive and the operation of the angular velocity sensor 1 will be described with reference to FIGS. FIG. 26 is a diagram showing a schematic configuration of a connection state of the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the oscillation start section T1 in X-Drive. FIG. 27 is a diagram showing a schematic configuration of a connection state of the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the stable oscillation section T2 in X-Drive. FIG. 28 is a diagram illustrating a schematic configuration of a connection state of the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the oscillation stop period T3 in X-Drive.

As shown in FIGS. 22 and 26, the connection relationship between the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the X-Drive oscillation start period T1 is the same as that of the Z-Drive except that the switch 54 is turned off. This is the same as the connection relationship in Drive. As shown in FIG. 5, among the output terminals of the rectangular wave generator 5b, one output terminal from which the rectangular wave drive signal Rct1 is output is connected to the drive electrode D1, and the other output terminal from which the rectangular wave drive signal Rct2 is output. The output terminal is connected to the drive electrode D2. Therefore, the rectangular wave drive signal Rct1 generated by the rectangular wave generator 5b is input to the drive electrode D1 as the oscillation control unit output signal Vdr via the switching circuit 5c, and the rectangular wave drive signal Rct2 generated by the rectangular wave generator 5b. Is input to the drive electrode D2 as the oscillation control unit output signal -Vdr via the switching circuit 5c.
Further, as described with reference to FIG. 21, the rectangular wave drive signal Rct1 and the rectangular wave drive signal Rct2 are signals having opposite phases. Therefore, the oscillation control unit 5 inputs the rectangular wave drive signals Rct1 and Rct2 having opposite phases to the drive electrodes D1 and D2 as the oscillation control unit output signal Vdr in the oscillation start period T1 during X-Drive.

In the stable oscillation section T2 of X-Drive, as shown in FIGS. 22 and 27, the connection relationship between the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c is Z except that the switch 54 is turned off. This is the same as the connection relationship of the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the stable drive oscillation period T2. The oscillation controller 5 inputs the self-excited oscillation signal Dr1 output from the amplifier 61a of the driver 6e to the drive electrode D1, and inputs the self-excited oscillation signal Dr2 output from the amplifier 62a of the driver 6e to the drive electrode D2. The self-excited oscillation signal Dr1 and the self-excited oscillation signal Dr2 are signals having opposite phases based on the self-excited oscillation of the angular velocity sensor unit 3 (see FIG. 5). For this reason, the drive electrode D1 and the drive electrode D2 are respectively driven by the self-excited oscillation signal Dr1 and the self-excited oscillation signal Dr2 having opposite phases, as in the oscillation start period T1. The self-excited oscillation circuit 5 a forms a 360 ° oscillation loop, and the frequency of the signal in the oscillation loop is drawn into the oscillation frequency of the angular velocity sensor unit 3, and the vibration unit 3 a of the angular velocity sensor unit 3 Continue to vibrate at frequency.

In the X-Drive oscillation stop period T3, as shown in FIGS. 22 and 28, the connection relationship between the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c is Z except that the switch 54 is turned off. This is the same as the connection relationship of the driver 6e, the rectangular wave generator 5b, and the switching circuit 5c in the oscillation stop period T3 of -Drive. The oscillation controller 5 drives the output signal output from the amplifier 61a of the driver 6e (ie, the self-excited oscillation signal Dr1) to the drive electrode D1, and outputs the output signal output from the amplifier 62a of the driver 6e (ie, the self-excited oscillation signal Dr2). Is driven to the drive electrode D2. Since the driver 6e functions as an inverting amplifier circuit, the self-excited oscillation signals Dr1 and Dr2 output from the driver 6e are signals whose phases are inverted by 180 ° with respect to the self-excited oscillation signals Dr1 and Dr2 in the stable oscillation period T2.

In the oscillation stop period T3 during X-Drive, the self-excited oscillation circuit 5a forms a 180 ° stable loop, reduces the self-excited oscillation amplitude based on the oscillation frequency of the angular velocity sensor unit 3, and stops the self-excited oscillation. . Therefore, the amplitudes of the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2 detected by the detection electrodes X1, X2, Y1, and Y2 gradually decrease and finally become zero. Accordingly, the carrier wave generation circuit 6b generates the carrier wave Vs generated based on the detection signals Vs_x1, Vs_x2, Vs_y1, and Vs_y2, the output signal Vi of the phase shifter 6c obtained by shifting the phase of the carrier wave Vs by 90 °, and the output signal Vi. The amplitude of each output signal Via output from the amplifier 6d also gradually decreases and finally becomes zero.
In addition, in the oscillation stop period T3 during X-Drive, the rectangular wave generator 5b is in a power-down state (non-operating state). For this reason, the output signals Rct1 and Rct2 are not output from the rectangular wave generator 5b.

<Support for 4-terminal drive sensor>
In the above embodiment, the angular velocity sensor of the two-terminal drive electrodes D1, D2 has been described, but the present invention is not limited to this. As shown in FIG. 29, the angular velocity sensor may be a four-terminal angular velocity sensor of drive electrodes D1x, D2x, D1y, and D2y. FIG. 29 is a block diagram showing a schematic configuration of the angular velocity sensor unit 3 including four-terminal drive electrodes D1x, D2x, D1y, and D2y. FIG. 29A shows signals input to the drive electrodes D1x, D2x, D1y, and D2y in Z-Drive, and FIG. 29B shows inputs to the drive electrodes D1x, D2x, D1y, and D2y in X-Drive. The signal to be shown is shown.
As shown in FIG. 29A, in the case of Z-Drive, the same output signal Vdr is input to the drive electrodes D1x, D2x, D1y, D2y. As shown in FIG. 29B, in the case of X-Drive, an output signal Vdrx is input to the drive electrode D1x, an output signal -Vdrx is input to the drive electrode D2x, and an operation common is applied to the drive electrodes D1y and D2y. The voltage VCOM is input.

[Second Embodiment]
The second embodiment of the present invention relates to an angular velocity sensor driving circuit, an angular velocity sensor device, and an angle sensor driving method.

2. Description of the Related Art Conventionally, there is an angular velocity sensor having a vibration part that can be displaced inside. An angular velocity sensor having a vibrating portion vibrates the vibrating portion at a predetermined frequency, and detects a displacement generated by a Coriolis force generated in the vibrating portion when an angular velocity is applied to the system. The angular velocity is detected based on the detected displacement.
Known angular velocity sensors are described in, for example, Patent Document 4 and Patent Document 5. The angular velocity sensors described in Patent Literature 4 and Patent Literature 5 both provide a drive signal to vibrate the vibrating portion in a predetermined axial direction and detect the angular velocity. In the angular velocity sensors described in Patent Literature 4 and Patent Literature 5, after the angular velocity is detected, the vibration of the vibration portion is stabilized, and the vibration portion is vibrated in another axial direction. In the following description, “statically” refers to a state in which the force applied to the vibrating portion including the weight portion is balanced and the vibrating portion can be regarded as stationary.

However, in the angular velocity sensor having a known vibration part, there is a possibility that an external force is applied to the weight included in the vibration part while the vibration part is stationary or before vibrating in any direction. When an external force is applied to the weight, the vibration unit vibrates in an unintended direction, and the angular velocity in a desired direction cannot be detected.
For example, it is conceivable that the vibration part vibrates in a direction other than the X-axis direction due to an external force or the like when the vibration part is in a section before being vibrated in the X-axis direction or is stopped. In such a case, the vibration component in the Y-axis direction and the Z-axis direction affects the vibration component in the X-axis direction, and the detection accuracy of the angular velocity in the X-axis direction decreases. Such a phenomenon occurs not only in the X-axis direction but also in detecting angular velocities in other directions.
The present embodiment has been made in view of such points, and when the angular velocity is detected by vibrating the weight of the vibrating portion in one axial direction, the weight vibrates in a direction other than the one axial direction. An object of the present invention is to provide an angular velocity sensor driving circuit, an angular velocity sensor device, and an angle sensor driving method that prevent this and has high angular velocity detection accuracy.

In order to solve the above-described problem in the present embodiment, an angular velocity sensor drive circuit according to one aspect of the present embodiment is an angular velocity sensor drive circuit that drives a weight portion including a drive electrode, and vibrates the weight portion in the first axis direction. Generating the first drive signal to be generated, the second drive signal for vibrating the weight portion in the second axis direction, and the first static signal for stabilizing the vibration of the weight portion in the first axis direction to generate the drive electrode And a signal generation circuit that outputs the first drive signal from the signal generation circuit to the drive electrode in a section from the detection of the angular velocity in the second axis direction to the detection of the angular velocity in the first axis direction. A first oscillation section is set, a first free section for freely vibrating the weight portion is set after the first oscillation section, and the first static signal is sent from the signal generation circuit after the first free section. The first output to the drive electrode A control circuit that sets an oscillation stop period and sets a second oscillation period in which the second drive signal is output from the signal generation circuit to the drive electrode immediately after the first oscillation stop period. And

An angular velocity sensor driving method according to one aspect of the present embodiment is an angular velocity sensor driving method for driving an angular velocity sensor having a weight portion, and the second oscillation direction is set in a first oscillation section that vibrates the weight portion in the first axis direction. A first oscillation stop period in which the angular velocity is detected, the weight portion is freely vibrated in the first free section after the first oscillation section, and the vibration in the first axial direction of the weight section after the first free section is stabilized. In addition, the vibration in the first axis direction of the weight part is settled, and the angular velocity in the first axis direction is detected in the second oscillation section in which the weight part immediately after the first oscillation stop section is vibrated in the second axis direction. It is characterized by.

The driving method of the angular velocity sensor according to one aspect of the present embodiment is an angular velocity sensor driving method for driving an angular velocity sensor having a weight portion provided with a drive electrode. In the first oscillation section that vibrates the weight portion in the first axis direction. The first drive signal is output to the drive electrode, and in the first free period after the first oscillation period, a constant voltage is supplied to the drive electrode or the drive electrode is in a floating state, and the first oscillation after the first free period In the stop period, a first stabilization signal for stabilizing the vibration in the first axis direction of the weight part is output to the drive electrode, and the weight part is placed in the second axis direction in the second oscillation period immediately after the first oscillation stop period. The second drive signal to be vibrated is output to the drive electrode.

According to one aspect of this embodiment, when the angular velocity is detected by vibrating the weight of the vibrating portion in one axial direction, the weight is prevented from vibrating in directions other than the one axial direction, and the angular velocity detection accuracy is reduced. Can provide a high angular velocity sensor driving circuit, an angular velocity sensor device, and a driving method of the angle sensor.

Hereinafter, a second embodiment (second embodiment to second to fourth embodiments) of the angular velocity sensor of the present invention will be described. The configuration requirements in the present embodiment and the configuration requirements in the first embodiment are associated as follows. The former is a configuration requirement in the present embodiment, and the latter is a configuration requirement in the first embodiment. The weight portion 223 corresponds to the vibration portion 3a, the drive electrode corresponds to the drive electrode, the angular velocity sensor drive circuit 231 corresponds to the oscillation control portion 5, the angular velocity detection circuit corresponds to the monitor portion 1a, and the signal generation circuit 310 corresponds to a circuit constituted by the self-excited oscillation circuit 5a, the rectangular wave generator 5b, and the switching circuit 5c, the rising signal generation circuit 311 corresponds to the rectangular wave generator 5b, and the feedback circuit 312 includes the HPF 6a and the carrier wave generation. The circuit 6b, a phase shifter circuit 6c, a variable amplifier 6d, and a driver 6e correspond to the circuit, and the output driver 313 corresponds to a circuit that includes the driver 6e and the switching circuit 5c.

First, prior to the description of the second embodiment, the configuration of the angular velocity sensor common to the 2-1 to 2-4 embodiments will be described.
Angular Velocity Sensor FIGS. 30A and 30B are diagrams for explaining the angular velocity sensor 201 according to the 2-1 embodiment to the 2-4 embodiment. 30A is a top view of the angular velocity sensor unit 210 included in the angular velocity sensor 201, and FIG. 30B is a cross-sectional view of the angular velocity sensor unit 210 along the line bb shown in FIG. 30A. FIG.
The angular velocity sensor 201 includes a support part 221, a weight part 223, and a flexible part 219 that connects the support part 221 and the weight part 223. The support part 221, the weight part 223, and the flexible part 219 constitute a basic structure as a vibration part of the angular velocity sensor part 210.

The electrode layer 217 is provided on the surface of the flexible portion 219 that is not supported by the support portion 221 (the upper surface of the flexible portion 219), and the back surface of the electrode layer 217 in contact with the flexible portion 219 (hereinafter, “ A piezoelectric layer 215 is provided on the upper surface of the electrode layer 217). Further, the drive electrode 211 _Xa , 211 _Xb , 211 _Ya , 211 _Yb , the detection electrode 213 _Xa , 213 _Xb , 213 _Ya , and the back surface (the upper surface of the piezoelectric layer 215) of the surface in contact with the upper surface of the electrode layer 217 of the piezoelectric layer 215 213 _Yb is provided.
30A and 30B, the X-axis direction, the Y-axis direction, and the Z-axis direction are defined as in the coordinate system shown in FIG. The Z axis is an axis along the normal line of the surfaces of the flexible portion 219 and the piezoelectric layer 215. The X axis and the Y axis are orthogonal to each other and also orthogonal to the Z axis. The weight part 223 can vibrate in the X-axis, Y-axis, and Z-axis directions.

As shown in FIG. 30 (a), the drive electrodes _211Xa , _211Xb , _211Ya , _211Yb are arranged so as to form a ring. The drive electrode 211 _Xa and the drive electrode 211 _{Xb face} each other, and the drive electrode 211 _Ya and the drive electrode 211 _{Yb face} each other. The detection electrodes 213 _Xa , 213 _Xb , 213 _Ya , and 213 _Yb are concentric with the ring formed by the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb , and the drive electrodes 211 _Xa , 211 _Xb , It arrange | positions so that the annular ring of the outer periphery of the annular ring comprised by 211 _Ya and 211 _Yb may be comprised. The detection electrode 213 _Xa and the detection electrode 213 _{Xb face} each other, and the detection electrode 213 _Ya and the detection electrode 213 _{Yb face} each other.

When a drive signal is input to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb , the piezoelectric layer 215 is distorted. When the piezoelectric layer 215 is distorted, the weight portion 223 vibrates in the Z-axis direction or the X-axis direction shown in the drawing. Specifically, the drive signal is supplied to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb with the electrode layer 217 shown in FIG. 30B grounded. At this time, the portions of the electrode layer 217 located below the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb expand and contract, and the weight portion 223 extends through the flexible portion 219 according to the expansion and contraction of the electrode layer 217. Vibrates in the axial direction or X-axis direction.

On the other hand, when the angular velocity is detected, if the Coriolis force is applied to the vibrating weight portion 223, the weight portion 223 is displaced in a direction orthogonal to the vibration direction. The piezoelectric layer 215 expands due to the displacement. The detection electrodes 213 _Xa , 213 _Xb , 213 _Ya , and 213 _Yb detect voltages generated by the expansion of the piezoelectric layer 215. For example, when the weight portion 223 is vibrated in the X-axis direction, Coriolis force is generated in the Z-axis direction perpendicular to the X-axis direction, and the generated Coriolis force is electrically transmitted to the detection electrodes 213 _Xa , 213 _Xb , 213 _Ya , and 213 _Yb . It is detected as a simple detection signal. The angular velocity of the Z-axis direction is detected from the value of the detection electrodes _{_{_{213 Xa, 213 Xb, 213 Ya}}} , 213 Yb detected by the detection signal.
Similarly, when the weight portion 223 is vibrated in the Z-axis direction, Coriolis force is generated in the X-axis direction or Y-axis direction perpendicular to the Z-axis direction, and the generated Coriolis force is detected by the detection electrodes 213 _Xa , 213 _Xb , 213 _Ya , 213 _Yb detects electrically. The angular velocity in the X-axis direction or the Y-axis direction is detected from the electrical values detected by the detection electrodes 213 _Xa , 213 _Xb , 213 _Ya , and 213 _Yb .

The angular velocity sensor unit 210 is not limited to the configuration shown in FIGS. 30 (a) and 30 (b). The angular velocity sensor unit may have any configuration as long as it is an angular velocity sensor unit that vibrates the weight part in directions of two or more axes. The weight portion only needs to be able to vibrate at least in the first axis direction and in the second axis direction different from the first axis direction. That is, any configuration may be used as long as the weight portion vibrates in two or more directions and angular velocity in two or more directions can be detected. As other configurations of the angular velocity sensor unit, for example, a device that uses a piezoelectric layer and supplies a drive signal with a capacitive element to detect a voltage can be considered. Furthermore, in the 2-1 embodiment to the 2-4 embodiment, the number of drive electrodes and detection electrodes is not limited.

Integrated Circuit FIG. 31 shows an application-specific integrated circuit (hereinafter simply referred to as “integrated circuit”) that detects an electrical signal by detecting a driving signal of the angular velocity sensor according to the 2-1 to 2-3 embodiments. Is a block diagram of ASIC (Application Specific Integrated Circuit). The integrated circuit 203 illustrated in FIG. 31 includes an angular velocity sensor drive circuit 231 and an angular velocity detection circuit 232.

As shown in FIG. 30 (a), the angular velocity sensor unit 210 has the drive electrodes ₂₁₁ _Xa, 211 _Xb, and 211 Ya, _{211 Yb,} and the detection electrodes _{_{_{213 Xa, 213 Xb, 213 Ya}}} , 213 Yb, the ing. The angular velocity sensor driving circuit 231 is a circuit for supplying a driving signal DX1, DX2, DY1, DY2 to the drive electrodes _{_{_{211 Xa, 211 Xb, 211 Ya}}} , 211 Yb. Angular velocity detecting circuit 232 detects a detection signal SX1, SX2, SY1, SY2 from the detection electrode _{_{_{213 Xa, 213 Xb, 213 Ya}}} , 213 Yb.

In FIG. 31, the drive signal DX1 output from the angular velocity sensor drive circuit 231 is a signal supplied to the drive electrode 211 _Xa , and the drive signal DX2 is a signal supplied to the drive electrode 211 _Xb . The drive signal DY1 output from the angular velocity sensor drive circuit 231 is a signal supplied to the drive electrode 211 _Ya , and the drive signal DY2 is a signal supplied to the drive electrode 211 _Yb .
In FIG. 31, the detection signal SX1 output from the angular velocity sensor unit 210 is a signal supplied from the detection electrode 213 _Xa , and the detection signal SX2 is a signal supplied from the detection electrode 213 _Xb . The detection signal SY1 output from the angular velocity sensor unit 210 is a signal supplied from the detection electrode 213 _Ya , and the detection signal SY2 is a signal supplied from the detection electrode 213 _Yb .
The angular velocity sensor drive circuit 231 processes the detection signals SX1, SX2, SY1, and SY2 to generate drive signals DX1, DX2, DY1, and DY2, and outputs them to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb . It can be configured as a self-oscillation loop.

Drive Signal FIG. 32 is a diagram illustrating drive signals applied to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb shown in FIG. In FIG. 32, the horizontal axis indicates time, and the vertical axis indicates a voltage value as a drive signal. The drive signal has a different waveform depending on each of the three sections of “oscillation start section”, “stable oscillation section”, and “oscillation stop section”. The oscillation start section is a section having a waveform for exciting the drive signal in the direction in which the weight portion 223 is desired to vibrate. The stable oscillation section is a section in which the drive signal has a waveform for stably vibrating the weight portion 223. The oscillation stop section is a section in which the drive signal has a waveform for stopping the vibration of the weight portion 223.

In the 2-1 to 2-4 embodiments, the oscillation start interval and the subsequent stable oscillation interval are also referred to as “oscillation interval”. In other words, the oscillation period includes an oscillation start period and a stable oscillation period.
In the oscillation start period, the amplitude of the waveform of the drive signal is large so that the amplitude of the weight portion 223 becomes a constant value in a short time. The drive signal output in the oscillation start period is also referred to as a “rising signal” in the second to second to fourth embodiments.

In the stable oscillation period, the drive signal is a signal having a constant amplitude and phase. The angular velocity sensor unit 210 detects angular velocity during the stable oscillation period. The drive signal output in the stable oscillation section is also referred to as “stable drive signal” in the 2-1 to 2-4 embodiments.
In the oscillation stop period, the drive signal has a waveform for stopping the vibration of the weight portion 223. The drive signal output in the oscillation stop period is also referred to as a “static signal” in the 2-1 to 2-4 embodiments.
The static signal shown in FIG. 32 is obtained when the angular velocity sensor drive circuit 231 constitutes a self-excited oscillation loop. When the angular velocity sensor drive circuit 231 forms a self-excited oscillation loop, the amplitude of the static signal decreases as the vibration of the weight portion 223 stabilizes. In addition, outputting the stabilization signal to stabilize the vibration of the weight part 223 is also referred to as “static stabilization processing” in this specification.

Next, an angular velocity sensor driving circuit according to the 2-1 embodiment of the present invention will be described.
[Second Embodiment]
FIG. 33 is a block diagram for explaining a configuration of an angular velocity sensor drive circuit 231 according to the 2-1 embodiment. The angular velocity sensor drive circuit 231 includes a signal generation circuit 310, an output driver 313, and a control circuit 314. The signal generation circuit 310 includes a rising signal generation circuit 311, a feedback circuit 312, and an output driver 313.

The rising signal generation circuit 311 outputs the rising signal SU having a large amplitude as shown in FIG. 32 in the oscillation start period. The rising signal US is a signal intended to set the amplitude of the weight portion 223 to a constant value in a short time. The rising signal SU shown in FIG. 32 is a pulse wave, but the rising signal SU is not limited to a pulse wave, and may be a sine wave.
The feedback circuit 312 generates a feedback signal SFb based on the detection signals SX1, SX2, SY1, and SY2, and outputs the generated feedback signal SFb to the output driver 313. The feedback signal SFb is a signal for stably vibrating the weight portion 223. The feedback signal SFb is generated by, for example, a method of adding two or four detection signals, shifting the phase by a predetermined amount, and appropriately amplifying the gain.

The output driver 313 receives the rising signal SU and the feedback signal SFb. The output driver 313 outputs drive signals DX1, DX2, DY1, and DY2 based on the rising signal SU to the angle sensor unit 210 in the oscillation start period.
Further, the output driver 313 generates a drive signal DX1, DX2, DY1, DY2 by processing the feedback signal SFb in accordance with the control of the control circuit 314 in the stable oscillation period, and generates the generated drive signals DX1, DX2, DY1, DY2 is output to the angular velocity sensor unit 210. At this time, the drive signals DX1, DX2, DY1, and DY2 generated from the feedback signal SFb based on the detection signals SX1, SX2, SY1, and SY2 are fed back to the angle sensor unit 210. As a result, a self-excited oscillation loop of “angular velocity sensor unit 210 → feedback circuit 312, output driver 313, angular velocity sensor unit 210” is formed.

With the above operation, the signal generation circuit 310 stabilizes the weight portion 223 of the angular velocity sensor unit 210 in the self-excited oscillation loop configured by the feedback circuit 312 after the oscillation is started by the start signal generation circuit 311. It can oscillate.
Further, the feedback circuit 312 of the signal generating circuit 310, the oscillation stop period, the vibration of the detection electrodes _{_{_{213 Xa, 213 Xb, 213 Ya}}} , 213 detection signals SX1 input from _Yb, SX2, SY1, weight portion 223 on the basis of the SY2 Is output to the angular velocity sensor unit 210 via the output driver 313. The static signal can be generated, for example, by inverting the phase of the stable drive signal output in the stable oscillation period. Further, in the angular velocity sensor driving circuit 231 of the second to first embodiments, the feedback circuit 312 is used to generate a static signal in accordance with the switching of the driving direction of the driving electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb. In particular, it may have a function of selecting an appropriate detection signal.

In addition, the control circuit 314 is free to apply a first oscillation section that vibrates the weight portion 223 in the Z-axis direction, a second oscillation section that vibrates the weight portion in the X-axis or Y-axis direction, and without applying external force to the weight portion 223. A first oscillation stop section in which the first free section to be vibrated and the vibration of the weight portion 223 in the X-axis direction are settled is set. For example, each section is set based on a clock signal (not shown), and the phase and amplitude of the feedback signal SFb are controlled according to the section, or the drive electrode to which the drive signal is output from the output driver 313 is switched. Can be done. The signals output in each section will be described later with reference to FIG.

Further, the control circuit 314 controls the power-up and power-down of the start signal generation circuit 311 in the oscillation start period. In addition, the control circuit 314 controls the feedback circuit 312 or the output driver 313 so as to invert the phase of the feedback signal SFb with the transition from the stable oscillation period to the oscillation stop period. By inverting the phase of the feedback signal SFb, a static signal based on the feedback signal SFb can be generated.

Further, the control circuit 314 switches the drive signals 211 _Xa , 211 _Xb , 211 _Ya , 211 _Yb and drives signals DX 1, DX 2 from the output driver 313 along with switching of the drive direction and transition from the oscillation start period to the stable oscillation period. , DY1 and DY2 are controlled.
Signal processing such as amplification of the rising signal SU and phase inversion can be performed by either the rising signal generation circuit 311 or the output driver 313. Signal processing such as amplification of the feedback signal SFb and phase inversion can be performed by either the feedback circuit 312 or the output driver 313.

The output driver 313 according to the second-first embodiment controls the drive signal 211 _Xa , 211 by switching the drive direction of the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , 211 _Yb under the control of the control circuit 314. It is also possible to switch whether four of _Xb , 211 _Ya , and 211 _Yb are output as in-phase signals, or output to the two drive electrodes as mutually opposite-phase signals. The control circuit controls the signal generation circuit to generate the drive signal as described above, switch to a static signal, switch the driving axial direction, and the like.

Operation Next, the operation of the configuration described above will be specifically described.
FIG. 34 is a diagram for explaining drive signals output to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb according to the 2-1 embodiment. FIG. 34 shows waveforms of the drive signals DX1, DX2, DY1, and DY2 shown in FIG. The horizontal axis of each drive signal is time, and the vertical axis is voltage value.

Further, in FIG. 34, “X stop”, “Y stop”, and “Z stop” indicate the oscillation stop sections in the X axis direction, the Y axis direction, and the Z direction, respectively. “Start up” indicates an oscillation start interval in the Z-axis direction and the X-axis direction, and “Measure” indicates a stable oscillation interval in which angular velocities in the X-axis direction, the Y-axis direction, and the Z-axis direction are detected. The “free section” is a section in which the weight portion 223 vibrates without receiving an external force.

In the 2-1 embodiment, the Z-axis direction corresponds to the first axis, and the X-axis direction and the Y-axis direction correspond to the second axis. A section “Measure (ωX, ωY detection)” shown in FIG. 34 detects the angular velocity ωX in the X-axis direction or the angular velocity ωY in the Y-axis direction by vibrating the weight portion 223 in the Z-axis direction. Corresponding to Further, the section “Measure (ωZ detection)” shown in FIG. 34 corresponds to the second stable oscillation section in which the weight portion 223 is vibrated in the X-axis direction to detect the angular velocity ωZ in the Z-axis direction. Furthermore, the sections “X stop” and “Y stop” shown in FIG. 34 correspond to the second oscillation stop section, and the section “Z stop” corresponds to the first oscillation stop section.

In the second-first embodiment, first, in order to detect the angular velocity ωX in the X-axis direction or the angular velocity ωY in the Y-axis direction, the weight portion 223 is vibrated in the Z-axis direction in the oscillation start period. Prior to this, in the angular velocity sensor of the 2-1 embodiment, vibrations in the X-axis direction and the Y-axis direction other than the Z-axis direction are settled in the oscillation stop period of “X stop” and “Y stop”.
In the example shown in FIG. 34, the signal generating circuit 310 generates a drive signal DX1, DX2 as the X-axis direction of the settling signals based on the feedback signal SFb, the driving electrodes ₂₁₁ of the angular velocity sensor unit 210 Xa, _{211 Xb} To supply. Subsequently, the signal generating circuit 310 generates a drive signal DY1, DY2 as a Y-axis direction of the settling signals based on the feedback signal SFb, supplied to the drive electrodes ₂₁₁ Ya, _{211 Yb} of the angular velocity sensor unit 210.

After stopping vibrations other than in the Z-axis direction, the rising signal generation circuit 311 shown in FIG. 33 outputs a pulse wave that is the rising signal SU to the output driver 313 in the oscillation start period in the Z-axis direction. The output driver 313 outputs the rising signal SU as drive signals DX1, DX2, DY1, and DY2. Driving signals DX1, DX2, DY1, DY2 is a phase pulse signal supplied to each of the four drive electrodes _{_{_{211 Xa, 211 Xb, 211 Ya}}} , 211 Yb.

In the stable oscillation section in the Z-axis direction, the control circuit 314 outputs the drive signals DX1, DX2, DY1, and DY2 that are stable drive signals based on the feedback signal SFb output from the feedback circuit 312 from the angular velocity sensor unit 210. The output driver 313 is controlled. For this reason, in the stable oscillation section, in-phase drive signals DX1, DX2, DY1, and DY2 based on the detection signals SX1, SX2, SY1, and SY2 are output to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb , respectively. . The angular velocity sensor unit 210 detects angular velocities ωX and ωY in the X-axis direction and the Y-axis direction during the stable oscillation section in the Z-axis direction.

Next, the control circuit 314 sets a free vibration section for freely vibrating the weight portion 223 after the stable oscillation section in the Z-axis direction. When detecting the angular velocity in the Z-axis direction after detecting the angular velocity in the X-axis direction and the Y-axis direction by setting the free vibration section, from detecting the angular velocity in the X-axis direction or the Y-axis direction to detecting the angular velocity in the Z-axis direction A certain blank time is provided between. The blank section is provided in this way, for example, in a mode in which the frequency of the time division operation for detecting the angular velocity is lowered or the power consumption is lowered.

The angular velocity sensor drive circuit according to the second to first embodiments provides a free section after the stable oscillation section in the Z-axis direction, and starts vibration in the X-axis direction immediately after stabilizing the Z-axis direction vibration after the free section. ing. As a result, even if vibration is generated by an external force in the blank section, the excess axial vibration component is settled before driving in the next axial direction, so that the angular velocity can be detected with high accuracy.
In the free section, the weight portion 223 vibrates freely without being affected by external force. The free vibration of the weight portion 223 can be realized by not outputting a drive signal to any of the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb . Free vibration can also be realized by the output driver 313 shown in FIG. 33 outputting a constant voltage to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb . Further, in the angular velocity sensor drive circuit of the 2-1 embodiment, the output driver 313 may place the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , 211 _Yb in a floating state in a free section where free vibration is performed.

Further, the angular velocity sensor drive circuit of the second to first embodiments grounds the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb via a resistance element in the free section to absorb the vibration energy of the weight part 223. Alternatively, the vibration of the weight portion 223 may be naturally damped.
Further, the angular velocity sensor drive circuit according to the 2-1 embodiment may reduce or eliminate the power supplied to the configuration other than the control circuit 314 in the free section. With such an operation, the angular velocity sensor drive circuit of the first embodiment can reduce the power consumption of the angular velocity sensor 201.

In the 2-1 embodiment, since the vibration in the Z-axis direction is stabilized immediately after the free section, the output driver 313 stabilizes the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , 211 _Yb in the Z-axis direction. Output a signal. The static signal in the Z-axis direction may be, for example, a signal obtained by inverting the phase of a signal having the same amplitude and cycle as the drive signals DX1, DX2, DY1, and DY2 as stable drive signals. The static signal in the Z-axis direction may be, for example, a signal obtained by amplifying the amplitudes of the drive signals DX1, DX2, DY1, and DY2 as stable drive signals and inverting the phase of a signal having the same period.

Further, in the 2-1 embodiment, after the oscillation stop period in the Z-axis direction, the rising signal generating circuit 311 shown in FIG. 33 generates a pulse wave as the rising signal SU in the X-axis direction. The output driver 313 controls the control circuit 313 to convert the rising signal SU into signals having opposite phases to each other and outputs the signals to the drive electrodes 211 _Xa and 211 _Xb . While the rising signal SU is output, the angular velocity sensor drive circuit 10 of the first embodiment is in the state of the oscillation start interval in the X-axis direction. After the oscillation start interval in the X-axis direction, the angular velocity sensor drive circuit 10 enters a stable oscillation interval in the X-axis direction.

In the stable oscillation section in the X-axis direction, the control circuit 314 controls the output driver 313 so as to output the feedback signal SFb instead of the rising signal SU. The feedback circuit 312 generates a feedback signal SFb based on the detection signals SX1 and SX2. The output driver 313 outputs the feedback signal SFb to the drive electrodes 211 _Xa and 211 _Xb as drive signals DX1 and DX2 having opposite phases. In the stable oscillation section in the X-axis direction, the angular velocity in the Z-axis direction is detected.

As described above, the angular velocity sensor drive circuit according to the 2-1 embodiment starts vibration in the desired direction immediately after stopping the vibration of the weight part 223 other than the desired direction. For this reason, the angular velocity sensor drive circuit according to the 2-1 embodiment can reduce the influence of vibration in a direction other than the direction desired to vibrate on the detection of the angular velocity, and can increase the detection accuracy of the angular velocity. In addition, the angular velocity sensor driving circuit according to the second to first embodiments can detect a predetermined direction in a predetermined direction even if noise enters a free section between the detection of the angular velocity in a predetermined direction and the detection of the angular velocity in another direction. Since the angular velocity is detected after performing the stabilization process, the angular velocity can be detected with high accuracy while stably vibrating the weight portion 223.

In the example shown in FIG. 34, in the oscillation stop period in the X-axis direction, the signals having the same amplitude and cycle as those of the drive signals DX1 and DX2 as the stable drive signals and having the phase inverted are set as the static signals. The output driver 313 outputs the static signal to the drive electrodes 211 _Xa and 211 _Xb as signals having opposite phases to each other. Thereafter, the output driver 313 outputs, to the drive electrodes 211 _Ya and 211 _Yb , static signals having the same amplitude and cycle as the stable drive signals DY1 and DY2 and having the phases reversed, as signals having opposite phases.

However, the angular velocity sensor driving circuit according to the second-first embodiment is not limited to such a configuration. For example, the rising signal generation circuit 311 generates rising signals SU having opposite phases, and the output driver 313 outputs the rising signals having opposite phases to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , 211 _Yb as static signals. It can also be output. Further, in the angular velocity sensor driving circuit of the second to first embodiments, the feedback circuit 312 can generate feedback signals SFb having opposite phases, and the control circuit 314 can switch the generated feedback signal SFb.

[Second Embodiment]
Next, an angular velocity sensor driving circuit according to a second to second embodiment of the present invention will be described. In the angular velocity sensor driving circuit according to the 2-2 embodiment, the angular velocity sensor and the integrated circuit have the same configuration as that of the first embodiment. For this reason, illustration and description of the configuration of the angular velocity sensor and the integrated circuit are omitted, and only control by the drive signal will be described.

FIG. 35 is a diagram for explaining drive signals output to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb according to the 2-2 embodiment. The horizontal axis of each drive signal in FIG. 35 is time, and the vertical axis is voltage value.
In FIG. 35, “X stop”, “Y stop”, and “Z Stop” indicate oscillation stop sections in the X axis direction, the Y axis direction, and the Z direction, respectively. “Start up” indicates an oscillation start interval in the X-axis direction and the Z-axis direction, and “Measure” indicates a stable oscillation interval in which the angular velocity is detected. The “free section” is a section in which the weight portion 223 vibrates without receiving an external force.

The angular velocity sensor drive circuit according to the second to second embodiments includes a second oscillation stop section in the Y-axis direction that stops the oscillation of the weight portion 223 in the Y-axis direction after the oscillation stop section in the Z-axis direction. This is different from the angular velocity sensor driving circuit of the embodiment.
In the second-first embodiment, as shown in FIG. 34, the static stabilization process in the Z-axis direction is performed prior to the detection of the angular velocity in the Z-axis direction. However, it is considered that the vibration of the weight portion 223 includes vibration components other than the Z-axis direction. The angular velocity sensor drive circuit according to the second to second embodiments pays attention to this point, and performs the stabilization process in the Y-axis direction following the stabilization process in the Z-axis direction. The angular velocity sensor drive circuit according to the 2-2 embodiment stabilizes the vibration of the weight portion 223 in the Y-axis direction, and then outputs a rising signal in the X-axis direction to the drive electrodes 211 _Xa and 211 _Xb to _cause the weight portion 223 to move. Vibrate in the X-axis direction.

Such an angular velocity sensor driving circuit according to the 2-2 embodiment can detect the angular velocity in the Z-axis direction with high accuracy in the stable oscillation section in the X-axis direction. In addition, the angular velocity sensor drive circuit of the 2-2 embodiment is configured so that the noise in the Z-axis direction and the Y-axis can be detected even if noise occurs between the detection of the angular velocity in the X-axis direction or the Y-axis direction and the detection of angular velocity in the Z-axis direction. Since the axial stabilization process is performed, the weight 223 can be stably vibrated and the angular velocity in the Z-axis direction can be detected with high accuracy.

[Second to Third Embodiment]
Next, an angular velocity sensor driving circuit according to the second to third embodiments of the present invention will be described. In the angular velocity sensor driving circuit according to the second to third embodiments, the angular velocity sensor and the integrated circuit have the same configuration as that of the second to first embodiments. For this reason, illustration and description of the configuration of the angular velocity sensor and the integrated circuit are omitted, and only control by the drive signal will be described.

FIG. 36 is a diagram for explaining drive signals output to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb according to the second to third embodiments. The horizontal axis of each drive signal in FIG. 35 is time, and the vertical axis is voltage value.
In FIG. 36, “X stop”, “Y stop”, and “Z Stop” indicate oscillation stop sections in the X axis direction, the Y axis direction, and the Z direction, respectively. “Start up” indicates an oscillation start interval in the X-axis direction and the Z-axis direction, and “Measure” indicates a stable oscillation interval in which angular velocities in the X-axis direction, the Y-axis direction, and the Z-axis direction are detected. The “free section” is a section in which the weight portion 223 vibrates without receiving an external force.

The angular velocity sensor drive circuit of the second to third embodiments is different from the second to first embodiments in that an oscillation stop interval in the Y-axis direction is set in parallel with an oscillation start interval in the X-axis direction. In the second to third embodiments, the rising signal in the X-axis direction and the static signal in the Y-axis direction are output in parallel.
The angular velocity sensor drive circuit according to the second to third embodiments performs a stabilization process in the oscillation stop period in the Z-axis direction prior to the detection of the angular velocity in the Z-axis direction, and performs Y during the oscillation start period in the Z-axis direction. The settling process is also performed in the axial direction. The angular velocity sensor drive circuit according to the second to third embodiments can detect the angular velocity in the Z-axis direction with high accuracy during the stable oscillation section in the X-axis direction. Further, the angular velocity sensor drive circuit according to the second to third embodiments can detect the Z-axis direction and the Y-axis even if noise occurs between the detection of the angular velocity in the X-axis direction or the Y-axis direction and the detection of the angular velocity in the Z-axis direction. Since the axial stabilization process is performed, the angular velocity in the Z-axis direction can be detected with high accuracy.
In addition, the angular velocity sensor driving circuit according to the second to third embodiments can increase the sampling frequency for angular velocity detection by simultaneously performing the stabilization process in the Z-axis direction and the start of oscillation in the X-axis direction.

[2-4 Embodiment]
Next, an angular velocity sensor driving circuit according to a second to fourth embodiment of the present invention will be described. In the angular velocity sensor drive circuit according to the 2-4 embodiment, the angular velocity sensor has the same configuration as that of the 2-1 embodiment. For this reason, in the second to fourth embodiments, illustration and description of the configuration of the angular velocity sensor are omitted, and control by the integrated circuit and the drive signal will be described.

FIG. 37 is a block diagram of the integrated circuit 205 of the angular velocity sensor according to the second to fourth embodiments. The integrated circuit 205 includes an angle sensor drive circuit 34 and an angular velocity detection circuit 232. The angular velocity sensor drive circuit 234 of the second to fourth embodiments operates without inputting the detection signals SX1, SX2, SY1, and SY2 input to the angular velocity detection circuit 232, and the angular velocity sensor drive of the 2-1 embodiment. This is different from the circuit 231.

FIG. 38 is a block diagram for explaining the angular velocity sensor drive circuit 234 shown in FIG. The angular velocity sensor drive circuit 234 includes a signal generation circuit 318 and a control circuit 323. The signal generation circuit 318 includes a drive signal generation circuit 319 and a switch circuit 315. The drive signal generation circuit 319 generates the drive signal Sd according to the control of the control circuit 323. The switch circuit 315 generates drive signals DX1, DX2, DY1, and DY2 based on the drive signal Sd under the control of the control circuit 323. At this time, in the second to fourth embodiments, the switch circuit 315 generates a static signal by inverting the phases of the drive signals DX1, DX2, DY1, and DY2 output in the stable oscillation period according to the control of the control circuit 323, respectively. To do. The switch circuit 315 switches the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _{Yb from} which the drive signals DX 1, DX 2, DY 1, and DY 2 are output.

FIG. 39 is a diagram for explaining drive signals output to the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb according to the second to fourth embodiments. The horizontal axis of each drive signal in FIG. 39 is time, and the vertical axis is voltage value.
In FIG. 39, “X stop”, “Y stop”, and “Z Stop” indicate oscillation stop sections in the X axis direction, the Y axis direction, and the Z direction, respectively. “Start up” indicates an oscillation start interval in the X-axis direction and the Z-axis direction, and “Measure” indicates a stable oscillation interval in which the angular velocity is detected. The “free section” is a section in which the weight portion 223 vibrates without receiving an external force.

In the angular velocity sensor drive circuit of the second to fourth embodiments, as shown in FIG. 39, the drive signal in the stable oscillation section is not a sine wave but a pulse wave. Such a difference from the 2-1 embodiment and the like occurs because the drive signals DX1, DX2, DY1, and DY2 of the 2-4 embodiment are not signals generated based on the feedback signal SFb. .
In addition, the switch circuit 315 of the second to fourth embodiments controls each of the drive electrodes 211 _Xa , 211 _Xb , 211 _Ya , and 211 _Yb of the weight part 223 to be in a floating state in the free section.

The angular velocity sensor driving circuit according to the second to fourth embodiments described above detects the angular velocity in the Z-axis direction with high accuracy during the stable oscillation section in the X-axis direction, similarly to the angular velocity sensor driving circuit according to the second to third embodiments. be able to. In addition, the angular velocity sensor drive circuit of the second to fourth embodiments can prevent the angular velocity in the Z-axis direction even if noise enters between the detection of the angular velocity in the X-axis direction or the Y-axis direction and the detection of the angular velocity in the Z-axis direction. Can be detected with high accuracy.
Further, the angular velocity sensor drive circuit of the second to fourth embodiments does not use the feedback circuit 312 of the angular velocity sensor drive circuit of the second to third embodiments. Therefore, the signal processing in the angular velocity sensor driving circuit can be simplified as compared with the second to third embodiments.

In addition, the angular velocity sensor drive circuit according to the 2-1 to 2-4 embodiments of the present invention is not limited to the configuration described above. For example, in the angular velocity sensor drive circuits according to the 2-1 embodiment to the 2-4 embodiment described above, the angular velocity is detected in the three axis directions of the Z-axis direction, the X-axis direction, and the Y-axis direction. Yes. However, the angular velocity sensor drive circuit of the 2-1 to 2-4 embodiments may detect an angular velocity only in the direction of one axis.

When detecting the angular velocity only in the direction of one axis, the angular velocity sensor drive circuits of the second to second to second embodiments can perform, for example, the Z-axis direction and the Y-axis direction before starting the oscillation in the X-axis direction. Oscillation in the X-axis direction may be started after stabilizing the vibration and stabilizing the vibration of the weight portion 223. Similarly, the oscillation in the Z-axis direction and the X-axis direction may be stabilized before the oscillation in the Y-axis direction is started, and the oscillation in the Y-axis direction may be started after stabilizing the oscillation of the weight portion 223.

Furthermore, the angular velocity sensor drive circuits of the 2-1 to 2-4 embodiments are not limited to those in which the drive signal output to the drive electrode when the angular velocity is detected includes a rising signal.
In addition, in the oscillation stop period after the free period, when the signal from the two detection electrodes among the four detection electrodes is fed back and the static signal is output to the drive electrode, the remaining two detection electrodes are short-circuited. Alternatively, the same common potential may be applied.
The present invention is not limited to the embodiment described above. Based on the knowledge of a person skilled in the art, design changes or the like may be added to the embodiments, and the embodiments may be arbitrarily combined, and aspects including such changes are also included in the technical scope of the present invention. It is.

One aspect of the first embodiment described above can be summarized as follows.
(Appendix 1)
An angular velocity sensor unit having a drive electrode, a vibration detection electrode, and a vibration unit;
A self-excited oscillation circuit that generates a self-excited oscillation signal to be output to the drive electrode based on a detection signal from the vibration detection electrode;
A drive signal generation circuit for generating a drive signal to be output to the drive electrode;
A switching circuit for switching whether to output the drive signal or the self-excited oscillation signal to the drive electrode;
A storage unit storing amplitude information for determining the amplitude of the drive signal of the drive signal generation circuit, or time information for determining the time for which the drive signal is output;
Angular velocity sensor with
(Appendix 2)
The angular velocity sensor according to claim 1, wherein the switching circuit switches the output to output the self-excited oscillation signal after the drive signal is output to vibrate the vibration unit.
(Appendix 3)
The drive signal generation circuit includes: a first drive signal that vibrates the vibration unit in a first axis direction; and a second drive signal that vibrates the vibration unit on a second axis that is orthogonal to the first axis direction. The angular velocity sensor according to

appendix

1 or 2, which outputs.
(Appendix 4)
The angular velocity sensor according to appendix 3, wherein the storage unit stores first amplitude information of the first drive signal and second amplitude information of the second drive signal.
(Appendix 5)
The angular velocity according to appendix 3 or 4, wherein the storage unit stores first time information at which the first drive signal is output and second time information at which the second drive signal is output. Sensor.
(Appendix 6)
The angular velocity sensor according to any one of appendices 1 to 5, wherein the drive signal is a rectangular wave.
(Appendix 7)
The angular velocity sensor according to any one of appendices 1 to 6, wherein the amplitude information and the time information are determined by an envelope of the detection signal.
(Appendix 8)
The angular velocity sensor according to any one of appendices 1 to 7, wherein the switching circuit switches to output the self-oscillation signal from the drive signal while an envelope of the detection signal has a linear characteristic.
(Appendix 9)
An angular velocity sensor unit having a drive electrode, a vibration detection electrode, and a vibration unit;
A self-excited oscillation circuit that generates a self-excited oscillation signal to be output to the drive electrode based on a detection signal from the vibration detection electrode;
A drive signal generation circuit for generating a drive signal to be output to the drive electrode;
A switching circuit for switching whether to output the drive signal or the self-excited oscillation signal to the drive electrode;
An amplitude detection unit for detecting the amplitude of the self-excited oscillation signal,
An angular velocity sensor that adjusts an amplitude of the drive signal of the drive signal generation circuit or a time during which the drive signal is output based on an amplitude detection signal of the amplitude detector.
(Appendix 10)
When the switching circuit outputs the drive signal to vibrate the vibration unit and then switches to output the self-excited oscillation signal, or after, the amplitude detection signal of the amplitude detection unit is greater than or equal to a predetermined value. In the case, the angular velocity sensor according to appendix 9, wherein an adjustment for reducing the amplitude of the drive signal or an adjustment for shortening the time during which the drive signal is output is performed.
(Appendix 11)
A signal output step of outputting a drive signal having a first amplitude to the drive electrode of the angular velocity sensor unit having a drive electrode, a vibration detection electrode, and a vibration unit;
A signal detection step of detecting a detection signal from the vibration detection electrode after elapse of a first time;
A signal comparison step of detecting the amplitude of the detection signal and comparing it with a target value;
A signal adjustment step for adjusting the first amplitude or the first time based on the comparison result;
Adjusting method of angular velocity sensor provided with
(Appendix 12)
The angular velocity sensor according to appendix 11, wherein when the amplitude of the detection signal is not a linear characteristic with respect to time, an adjustment for decreasing the amplitude of the drive signal or an adjustment for shortening the time during which the drive signal is output is performed. Adjustment method.
(Appendix 13)
As a result of the comparison, if the amplitude detection signal is larger than a target value, the angular velocity according to appendix 11 or 12, wherein an adjustment for decreasing the amplitude of the drive signal or an adjustment for shortening the time during which the drive signal is output is performed. Sensor adjustment method.
(Appendix 14)
As a result of the comparison, when the amplitude detection signal is smaller than a target value, any one of Supplementary notes 11 to 13 is performed to adjust the drive signal to increase the amplitude or to increase the drive signal output time. An adjustment method of the angular velocity sensor according to one item.

One aspect of the second embodiment described above can be summarized as follows.
(Appendix 1)
In the angular velocity sensor drive circuit for driving the weight portion provided with the drive electrode,
A first driving signal that vibrates the weight portion in the first axis direction, a second driving signal that vibrates the weight portion in the second axis direction, and a first static that stabilizes the vibration of the weight portion in the first axis direction. A signal generation circuit that generates a constant signal and outputs the constant signal to the drive electrode;
In a section from detection of the angular velocity in the second axis direction to detection of the angular velocity in the first axis direction, a first oscillation section in which the first drive signal is output from the signal generation circuit to the drive electrode is set. A first free section for freely vibrating the weight portion is set after the first oscillation section, and the first static signal is output from the signal generation circuit to the drive electrode after the first free section. A control circuit that sets one oscillation stop period and sets a second oscillation period in which the second drive signal is output from the signal generation circuit to the drive electrode immediately after the first oscillation stop period;
An angular velocity sensor driving circuit comprising:
(Appendix 2)
The signal generation circuit further generates a second static signal for stabilizing the vibration of the weight portion in the second axis direction, and outputs the second static signal to the drive electrode.
The control circuit sets a second free section in which the weight portion freely vibrates after the second oscillation section, and after the second free section, the second static signal is sent from the signal generation circuit to the drive electrode. The angular velocity sensor drive circuit according to appendix 1, wherein a second oscillation stop period to be output is set, and the first oscillation period is set immediately after the second oscillation stop period.
(Appendix 3)
The first drive signal includes a first rising signal for causing the weight portion to start vibration in the first axial direction, and a first stable drive signal for stabilizing the vibration in the first axial direction, and the second drive signal. Includes a second rising signal for causing the weight portion to start vibration in the second axial direction and a second stable drive signal for stabilizing the vibration in the second axial direction,
The control circuit sets a first oscillation start period in which the first rising signal is output from the signal generation circuit to the drive electrode in the first oscillation period, and the first oscillation start period is followed by the first oscillation period. A first oscillation oscillation period in which a stable drive signal is output to the drive electrode is set, and a second oscillation start period in which the second rising signal is output from the signal generation circuit to the drive electrode in the second oscillation period. The angular velocity sensor drive circuit according to appendix 2, wherein a second stable oscillation section in which the second stable drive signal is output to the drive electrode is set after the second oscillation start section.
(Appendix 4)
The angular velocity sensor drive according to appendix 3, wherein the control circuit sets the second oscillation start interval immediately after the first oscillation stop interval and sets the first oscillation start interval immediately after the second oscillation stop interval. circuit.
(Appendix 5)
The angular velocity sensor drive circuit according to any one of appendix 1 to appendix 4,
An angular velocity sensor comprising: the drive electrode to which a drive signal is supplied by the angular velocity sensor drive circuit; the weight portion that vibrates according to the drive signal; and a detection electrode that outputs a detection signal output by vibration of the weight portion;
An angular velocity detection circuit for detecting an angular velocity from the detection signal output from the detection electrode;
An angular velocity detection sensor device comprising:
(Appendix 6)
An angular velocity sensor driving method for driving an angular velocity sensor having a weight portion,
Detecting an angular velocity in the second axis direction in a first oscillation section that vibrates the weight portion in the first axis direction;
In the first free section after the first oscillation section, the weight portion is allowed to freely vibrate,
In the first oscillation stop section for stabilizing the vibration in the first axial direction of the weight portion after the first free section, the vibration in the first axial direction of the weight portion is stabilized.
An angular velocity sensor driving method for detecting an angular velocity in the first axis direction in a second oscillation interval in which the weight portion immediately after the first oscillation stop interval is vibrated in the second axis direction.
(Appendix 7)
An angular velocity sensor driving method for driving an angular velocity sensor having a weight portion provided with a drive electrode,
Outputting a first drive signal to the drive electrode in a first oscillation section that vibrates the weight portion in a first axis direction;
The first free section after the first oscillation section supplies a constant voltage to the drive electrode or sets the drive electrode in a floating state,
In a first oscillation stop section after the first free section, a first static signal for stabilizing the vibration in the first axial direction of the weight portion is output to the drive electrode,
A method for driving an angular velocity sensor, wherein a second drive signal for oscillating the weight portion in a second axis direction is output to the drive electrode in a second oscillation section immediately after the first oscillation stop section.

1,201

Angular velocity sensor

1a, 1b Monitor unit 3,210 Angular velocity sensor unit 3a Vibration unit 5 Oscillation control unit 5a Self-excited oscillation circuit 5b Rectangular wave generator 5c Switching circuit 5d Reference value generation unit 5e Sequencer 5f Control unit 6a HPF
6b Carrier wave generation circuit 6c Phase shifter 6d Variable amplifier 6e Driver 203, 205 Integrated circuit 215 Piezoelectric layer 217 Electrode layer 219 Flexible portion 221 Support portion 223

Weight portions

231, 233, 234 Angular velocity sensor drive circuit 232 Angular

velocity detection circuit

310, 318 Signal Generation circuits 311 and 316 Rising signal generation circuits 312 and 317 Feedback circuit 313

Output drivers

314 and 323 Control circuit 315 Switch circuit 319 Drive signal generation circuit

Claims

An angular velocity sensor drive circuit that vibrates a drive electrode, a detection electrode, and a sensor unit having a vibration unit,
A vibration start signal generation circuit for generating a vibration start signal;
An excitation circuit that generates an excitation signal based on a detection signal from the detection electrode;
An output unit for outputting the vibration start signal to the drive electrode in a vibration start period for starting vibration of the vibration unit, and outputting the excitation signal to the drive electrode in an angular velocity detection section for detecting an angular velocity;
A control unit that controls the output unit so that the vibration start section and the angular velocity detection section are repeated;
An adjustment unit that adjusts the energy of the vibration start signal applied to the drive electrode during the next vibration start interval based on the amplitude of the detection signal or the excitation signal of the angular velocity detection interval or the variation amount of the amplitude;
An angular velocity sensor driving circuit comprising:
The adjustment unit is
When the amplitude of the detection signal or the excitation signal in the angular velocity detection section is larger than a reference value, and when the variation amount of the amplitude of the detection signal or the excitation signal in the angular velocity detection section is larger than a reference value, Adjustment is made so that the energy of the vibration start signal applied to the drive electrode during the vibration start interval set later is smaller than the energy of the vibration start signal applied to the drive electrode during the previous vibration start interval. ,
When the amplitude of the detection signal or the excitation signal in the angular velocity detection section is smaller than a reference value, and when the variation amount of the amplitude of the detection signal or the excitation signal in the angular velocity detection section is smaller than a reference value, Adjustment is made so that the energy of the vibration start signal applied to the drive electrode during the vibration start interval set later is larger than the energy of the vibration start signal applied to the drive electrode during the previous vibration start interval. The angular velocity sensor drive circuit according to claim 1.
The angular velocity sensor drive circuit according to claim 1, wherein the adjustment unit adjusts an amplitude of the vibration start signal or a time during which the vibration start signal is output to the drive electrode.
The vibration start signal generation circuit includes a first vibration start signal that vibrates the vibration part in a first axis direction, and a second vibration start signal that vibrates the vibration part on a second axis that is orthogonal to the first axis direction. Generate,
The output unit outputs a first vibration start signal to the drive electrode and detects a first angular velocity in a first vibration start section in which vibration starts in the first axis direction of the vibration unit, and detects a first angular velocity. In the section, the excitation signal is output to the drive electrode, the second vibration start signal is output to the drive electrode in a second vibration start section that starts vibration in the second axial direction of the vibration unit, and the second In the second angular velocity detection section for detecting the angular velocity, the excitation signal is output to the drive electrode,
The control unit controls the output unit such that the first vibration start section, the first angular velocity detection section, the second vibration start section, and the second angular speed detection section are repeated. The angular velocity sensor drive circuit according to any one of claims 3 to 4.
The adjustment unit is configured to detect a first vibration start signal applied to the drive electrode during the next first vibration start section based on the amplitude of the detection signal or the excitation signal in the first angular velocity detection section or the variation amount of the amplitude. The energy of the second vibration start signal applied to the drive electrode during the next second vibration start section is adjusted based on the amplitude of the detection signal or the excitation signal in the second angular velocity detection section or the amount of fluctuation of the amplitude. The angular velocity sensor drive circuit according to claim 4, wherein the energy is adjusted.
An angular velocity sensor drive circuit according to any one of claims 1 to 5,
A drive electrode, a detection electrode, and a sensor unit having a vibration unit;
An angular velocity sensor comprising:
Outputting a vibration start signal to the drive electrode of the angular velocity sensor unit in a vibration start section in which vibration of the vibration unit of the angular velocity sensor unit is started;
Outputting an excitation signal generated based on a detection signal from a detection electrode of the angular velocity sensor unit to the drive electrode in an angular velocity detection section for detecting an angular velocity;
Changing the amplitude or time of the vibration start signal to be output to the drive electrode in the next vibration start section based on the amplitude of the detection signal or the excitation signal in the angular velocity detection section or the variation amount of the amplitude; and ,
An angular velocity sensor driving method comprising:
In the angular velocity sensor drive circuit for driving the weight portion provided with the drive electrode,
A first driving signal that vibrates the weight portion in the first axis direction, a second driving signal that vibrates the weight portion in the second axis direction, and a first static that stabilizes the vibration of the weight portion in the first axis direction. A signal generation circuit that generates a constant signal and outputs the constant signal to the drive electrode;
In a section from detection of the angular velocity in the second axis direction to detection of the angular velocity in the first axis direction, a first oscillation section in which the first drive signal is output from the signal generation circuit to the drive electrode is set. A first free section for freely vibrating the weight portion is set after the first oscillation section, and the first static signal is output from the signal generation circuit to the drive electrode after the first free section. A control circuit that sets one oscillation stop period and sets a second oscillation period in which the second drive signal is output from the signal generation circuit to the drive electrode immediately after the first oscillation stop period;
An angular velocity sensor driving circuit comprising:
The signal generation circuit further generates a second static signal for stabilizing the vibration of the weight portion in the second axis direction, and outputs the second static signal to the drive electrode.
The control circuit sets a second free section in which the weight portion freely vibrates after the second oscillation section, and after the second free section, the second static signal is sent from the signal generation circuit to the drive electrode. The angular velocity sensor drive circuit according to claim 8, wherein an output second oscillation stop section is set, and the first oscillation section is set immediately after the second oscillation stop section.
The first drive signal includes a first rising signal for causing the weight portion to start vibration in the first axial direction, and a first stable drive signal for stabilizing the vibration in the first axial direction, and the second drive signal. Includes a second rising signal for causing the weight portion to start vibration in the second axial direction and a second stable drive signal for stabilizing the vibration in the second axial direction,
The control circuit sets a first oscillation start period in which the first rising signal is output from the signal generation circuit to the drive electrode in the first oscillation period, and the first oscillation start period is followed by the first oscillation period. A first oscillation oscillation period in which a stable drive signal is output to the drive electrode is set, and a second oscillation start period in which the second rising signal is output from the signal generation circuit to the drive electrode in the second oscillation period. The angular velocity sensor drive circuit according to claim 9, wherein a second stable oscillation section in which the second stable drive signal is output to the drive electrode is set after the second oscillation start section.
The angular velocity sensor according to claim 10, wherein the control circuit sets the second oscillation start period immediately after the first oscillation stop period and sets the first oscillation start period immediately after the second oscillation stop period. Driving circuit.
The angular velocity sensor drive circuit according to any one of claims 1 to 4,
An angular velocity sensor comprising: the drive electrode to which a drive signal is supplied by the angular velocity sensor drive circuit; the weight portion that vibrates according to the drive signal; and a detection electrode that outputs a detection signal output by vibration of the weight portion;
An angular velocity detection circuit for detecting an angular velocity from the detection signal output from the detection electrode;
An angular velocity detection sensor device comprising:
An angular velocity sensor driving method for driving an angular velocity sensor having a weight portion,
Detecting an angular velocity in the second axis direction in a first oscillation section that vibrates the weight portion in the first axis direction;
In the first free section after the first oscillation section, the weight portion is allowed to freely vibrate,
In the first oscillation stop section for stabilizing the vibration in the first axial direction of the weight portion after the first free section, the vibration in the first axial direction of the weight portion is stabilized.
An angular velocity sensor driving method for detecting an angular velocity in the first axis direction in a second oscillation interval in which the weight portion immediately after the first oscillation stop interval is vibrated in the second axis direction.
An angular velocity sensor driving method for driving an angular velocity sensor having a weight portion provided with a drive electrode,
Outputting a first drive signal to the drive electrode in a first oscillation section that vibrates the weight portion in a first axis direction;
The first free section after the first oscillation section supplies a constant voltage to the drive electrode or sets the drive electrode in a floating state,
In a first oscillation stop section after the first free section, a first static signal for stabilizing the vibration in the first axial direction of the weight portion is output to the drive electrode,
A method for driving an angular velocity sensor, wherein a second drive signal for causing the weight portion to vibrate in a second axis direction is output to the drive electrode in a second oscillation section immediately after the first oscillation stop section.