WO2022004563A1 - 振動型ジャイロ素子及びこれを備えた角速度センサ - Google Patents
振動型ジャイロ素子及びこれを備えた角速度センサ Download PDFInfo
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- WO2022004563A1 WO2022004563A1 PCT/JP2021/024034 JP2021024034W WO2022004563A1 WO 2022004563 A1 WO2022004563 A1 WO 2022004563A1 JP 2021024034 W JP2021024034 W JP 2021024034W WO 2022004563 A1 WO2022004563 A1 WO 2022004563A1
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- 238000001514 detection method Methods 0.000 claims description 261
- 230000002093 peripheral effect Effects 0.000 claims description 6
- 230000004048 modification Effects 0.000 description 27
- 238000012986 modification Methods 0.000 description 27
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 13
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 13
- 229910052710 silicon Inorganic materials 0.000 description 13
- 239000010703 silicon Substances 0.000 description 13
- 229910052814 silicon oxide Inorganic materials 0.000 description 13
- 238000010586 diagram Methods 0.000 description 6
- 238000005530 etching Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000005459 micromachining Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/567—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode
- G01C19/5677—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
- G01C19/5684—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
Definitions
- the present disclosure relates to a vibrating gyro element and an angular velocity sensor equipped with the vibration type gyro element.
- a vibration type gyro element is known as a gyro element used for an angular velocity sensor.
- a vibration type gyro element used for an angular velocity sensor.
- an electromagnetic gyro element having a structure in which a plurality of electrodes are provided on the surface of an annular oscillator and a magnetic field is applied in a direction intersecting the surface of the electrodes is well known (see, for example, Patent Documents 1 and 2).
- a current having a frequency corresponding to the resonance frequency of the vibrator is passed through some electrodes (hereinafter referred to as Primary Driving Electrode)) to transmit the vibrator.
- Primary Driving Electrode Resonant vibration
- Secondary vibration also referred to as primary vibration
- the voltage generated in another electrode hereinafter referred to as a secondary detection electrode (Secondary Pickoff Electrode)
- secondary detection electrode Secondary Pickoff Electrode
- the alternating current flowing through the primary drive electrode may cause mutual induction in the secondary detection electrode and induce a voltage (hereinafter, crosstalk voltage). Sometimes called).
- Such a crosstalk voltage was superimposed on the output signal as an error component, and sometimes became an error factor of the detection value of the angular velocity.
- the present disclosure has been made in view of this point, and an object thereof is to provide a vibrating gyro element capable of reducing the crosstalk voltage included in the voltage generated in the secondary detection electrode and an angular velocity sensor including the vibration type gyro element. There is something in it.
- the vibration type gyro element includes a fixed portion, a vibrator, and a support portion for connecting the vibrator to the fixed portion to vibrately support the vibrator.
- the oscillator is provided with at least an electrode formed in the plane of the oscillator and the oscillator has a vibration mode of cosN ⁇ (N is a natural number of 2 or more)
- the axis of the electrode is equal to or equal to the outer peripheral direction of the oscillator.
- the electrodes are arranged in 4N directions arranged at angular intervals, and the plurality of electrodes are a primary drive electrode that excites the primary vibration of the cosN ⁇ mode in the vibrator, and a secondary vibration of the vibrator.
- the number of cases where the primary drive electrode is arranged in the direction adjacent to the clockwise side with respect to the secondary detection electrode is S1 and the secondary detection electrode is included.
- the number of cases where the primary drive electrode is arranged in an orientation adjacent to the counterclockwise side is S2, and the primary drive electrode is either an orientation adjacent to the clockwise side or an orientation adjacent to the counterclockwise side.
- the angular velocity sensor is a vibration type gyro element, a primary AC power supply that applies AC power of a predetermined frequency to the primary drive electrode, and a secondary detection that detects a voltage signal generated in the secondary detection electrode. It includes at least a unit and a calculation unit that calculates an angular velocity based on the output signal of the secondary detection unit.
- the crosstalk voltage included in the voltage generated by the secondary detection electrode can be reduced.
- the crosstalk voltage included in the output signal of the vibration type gyro element can be reduced, and the detection accuracy of the angular velocity can be improved.
- FIG. 1 is a cross-sectional view taken along the line II-II of FIG. It is an enlarged view of the part surrounded by the broken line of FIG.
- It is a schematic block diagram of the circuit block of the angular velocity sensor. It is a schematic diagram which shows the primary vibration state of a vibrator. It is a schematic diagram which shows the secondary vibration state of a vibrator. It is a top view which shows the crosstalk voltage generation place during operation of a vibrating gyro element. It is a top view which shows the crosstalk voltage generation place during operation of the vibration type gyro element for comparison.
- FIG. 1 It is a top view of the vibration type gyro element which concerns on modification 1.
- FIG. 2 is a top view of another vibration type gyro element which concerns on modification 1.
- FIG. 2 is a top view of another vibration type gyro element which concerns on modification 1.
- FIG. 2 is a top view of the vibration type gyro element which concerns on modification 2.
- FIG. 2 is a top view of another vibration type gyro element which concerns on modification 2.
- FIG. It is a top view of the vibration type gyro element which concerns on modification 3.
- FIG. It is a top view of the vibration type gyro element which concerns on modification 4.
- FIG. 4 It is a top view of the vibration type gyro element which concerns on modification 4.
- FIG. It is a top view of another vibration type gyro element which concerns on modification 4.
- FIG. It is a top view of the vibration type gyro element which concerns on modification 5.
- FIG. It is a top view of another vibration type gyro element which concerns on modification 5.
- FIG. It is a figure which shows the relationship between the arrangement relation of the primary drive electrode and the secondary detection electrode, and the reduction condition of a crosstalk voltage.
- FIG. It is an enlarged view of the part surrounded by the broken line of FIG. It is a schematic block diagram of the circuit block of the angular velocity sensor.
- FIG. 1 is a plan view of the vibrating gyro element according to the first embodiment
- FIG. 2 is a sectional view taken along line II-II of FIG. 1
- FIG. 3 is a portion surrounded by a broken line in FIG. Enlarged views are shown respectively.
- FIGS. 1 to 3 schematically show the structure of the vibrating gyro element 100 and do not correctly represent the actual dimensional relationship between the members.
- the radial direction of the vibrator 20 may be referred to as a radial direction
- the outer peripheral direction of the vibrator 20 may be referred to as a circumferential direction
- the direction intersecting the radial direction and the circumferential direction may be referred to as an axial direction.
- the central side of the vibrator 20 may be referred to as an inner or inner side
- the outer peripheral side may be referred to as an outer or outer side.
- the side provided with the upper yoke 61 (see FIG. 2) may be referred to as the upper or upper side
- the side provided with the lower yoke 63 may be referred to as the lower or lower side.
- the upper surface of each member shown below may be referred to as a front surface
- the lower surface may be referred to as a back surface.
- one or a plurality of primary drive electrodes may be collectively referred to as a primary drive electrode PD, and one or a plurality of secondary detection electrodes may be collectively referred to as a secondary detection electrode SPO.
- the vibration type gyro element 100 has a fixed portion 10, a vibrator 20, a plurality of support portions 30, a plurality of electrodes 40a to 40h, and a magnetic field application portion 60.
- the fixing portion 10 has an opening 10a in the center, and an oscillator 20, a plurality of support portions 30, a plurality of electrodes 40a to 40h, and a magnetic field application portion 60 are arranged inside the opening 10a. ing. Further, as shown in FIG. 2, the fixing portion 10 is a member having a laminated structure in which the first silicon layer 51, the silicon oxide layer (insulating layer) 52, and the second silicon layer 53 are laminated in this order. Further, a silicon oxide film 54 is formed on the surface of the second silicon layer 53.
- the vibrator 20 is an annular member obtained by processing the second silicon layer 53, and has a vibration mode of cos2 ⁇ .
- the support portion 30 is a member obtained by processing the second silicon layer 53, and is integrally formed with the vibrator 20. Further, the support portion 30 connects the oscillator 20 to the fixed portion 10 to support the oscillator 20 in a cantilevered manner, or from another point of view, the oscillator 20 so as to be vibrable.
- each of the plurality of support portions 30 has a first leg portion 31 and a second leg portion 32.
- the first leg portion 31 and the second leg portion 32 have a first end portion 30a and a second end portion 30b, respectively.
- the first end portions 30a are connected to different positions of the vibrator 20 with a first interval.
- the second end portions 30b are connected to different positions of the fixing portions 10 with a second interval narrower than the first interval.
- first leg portion 31 is modified by a first portion 31a extending radially outward from the first end portion 30a and a first variable portion 31b which is one end of the first portion 31a. It has a second portion 31c extending parallel to the outer periphery of the oscillator 20. Further, the first leg portion 31 is modified by the second variable portion 31d, which is one end of the second portion 31c, and extends outward in the radial direction of the vibrator 20 to reach the second end portion 30b. have.
- the second leg portion 32 is modified by a first portion 32a extending radially outward from the first end portion 30a and a first variable portion 32b which is one end of the first portion 32a.
- a second portion 32c extending parallel to the outer periphery of the oscillator 20.
- the second leg portion 32 is modified by the second variable portion 32d, which is one end of the second portion 32c, and extends outward in the radial direction of the vibrator 20 to reach the second end portion 30b. have.
- the second portion 31c of the first leg portion 31 and the second portion 32c of the second leg portion 32 extend to the second variable portions 31d and 32d so as to approach each other. Further, the third portion 31e of the first leg portion 31 and the third portion 32e of the second leg portion 32 are arranged in parallel from the second variable portions 31d and 32d to the second end portion 30b while keeping a predetermined interval. Each is extended. Further, the first leg portion 31 and the second leg portion 32 are arranged symmetrically with respect to a virtual line passing between the center of the vibrator 20 and between the third portions 31e and 32e of each other.
- Each of the electrodes 40a to 40h is a conductive member formed in a loop shape in the plane of the vibrator 20. Further, each of the electrodes 40a to 40h is formed so as to extend toward the surfaces of the support portion 30 and the fixing portion 10. For example, as shown in FIG. 3, the electrode 40d passes from the second end portion 30b of the first leg portion 31 to the oscillator 20 between the first leg portion 31 and the first end portion 30a and the second leg portion 32. Then, it extends to the second end portion 30b of the second leg portion 32. Further, the electrode 40d is formed on the surface of the silicon oxide film 54.
- the electrodes 40a to 40h may be collectively referred to as the electrode 40.
- the electrodes 40a to 40p (see FIG. 14) shown later may also be referred to as electrodes 40 in the same manner.
- some or all of the electrodes 40 having the same function arranged in different directions are connected by wiring (not shown) provided in the fixed portion 10.
- the "direction" in the present specification corresponds to the "region" in which the electrode 40 is arranged, and when the regions are adjacent to each other, these are continuous.
- the electrodes 40 may be arranged across one direction. Further, the size of the electrode 40 may be smaller than the size of one direction (region).
- a plurality of electrodes 40 may be arranged in the same direction.
- four primary drive electrodes PD and four secondary detection electrodes SPO are arranged alternately in the circumferential direction.
- the primary drive electrode PD and the primary drive electrode PD closest to the primary drive electrode PD are arranged at positions 90 degrees apart from each other.
- the first secondary detection electrode SPO and the nearest secondary detection electrode SPO are arranged at positions 90 degrees apart from each other.
- the adjacent primary drive electrode PD and the secondary detection electrode SPO are arranged at positions separated from each other by 45 degrees.
- Electrode pads are provided at both ends of each of the plurality of electrodes 40a to 40h.
- the four secondary detection electrodes SPO are connected in series via an electrode pad.
- the magnetic field application unit 60 has an upper yoke 61, a magnet 62, and a lower yoke 63.
- the upper yoke 61 and the lower yoke 63 are bottomed tubular members made of a magnetic material such as iron, respectively.
- the upper yoke 61 and the lower yoke 63 are arranged so that the tubular portion of the upper yoke 61 and the tubular portion of the lower yoke 63 face each other with an axial interval.
- the oscillator 20 is arranged between the tubular portion of the upper yoke 61 and the tubular portion of the lower yoke 63.
- the vibrator 20 is arranged between the tubular portion of the upper yoke 61 and the tubular portion of the lower yoke 63 with an axial distance from each other.
- One of the upper part and the lower part of the magnet 62 is an N pole, and the other is an S pole.
- the magnet 62 is held by the upper yoke 61, the lower yoke 63, or both, and is fixedly arranged inside the vibrator 20.
- the magnetic flux flowing from one magnetic pole of the magnet 62 passes through one of the upper yoke 61 and the lower yoke 63 and reaches the electrodes 40a to 40h formed in the vibrator 20 and its plane. Further, the magnetic flux passes through the vibrator 20 and the electrodes 40a to 40h, passes through the other of the upper yoke 61 and the lower yoke 63, and flows into the other magnetic pole of the magnet 62.
- the magnetic field application unit 60 applies a magnetic field to the plurality of electrodes 40a to 40h in the direction intersecting the surface of the vibrator 20, in this case, in the axial direction.
- the magnetic field application unit 60 is supported by a support substrate (not shown) to maintain its radial and axial positions with the vibrator 20.
- the vibrating gyro element 100 excluding the magnetic field application unit 60 is a MEMS (Micro Electro Mechanical Systems) obtained by processing a known SOI (Slicon On Insulator) substrate by using, for example, a micromachining technique to which a semiconductor microfabrication technique is applied. ) It is an element.
- MEMS Micro Electro Mechanical Systems
- SOI Silicon On Insulator
- This MEMS element is manufactured, for example, as follows.
- the SOI substrate having the first silicon layer 51, the silicon oxide layer 52, and the second silicon layer 53 is thermally oxidized to form a silicon oxide film 54 on the surface of the second silicon layer 53.
- a plurality of electrodes 40a to 40h are formed on the surface of the silicon oxide film 54 using a mask pattern (not shown).
- a plurality of electrodes 40a to 40h are formed by applying a metal film to the surface of the silicon oxide film 54 through a mask pattern.
- the silicon oxide film 54 and the second silicon layer 53 are etched and removed up to the silicon oxide layer 52. Through this step, the original shape of the support portion 30 and the oscillator 20 is formed.
- the support portion 30 and the support portion 30 and the support portion 30 and the support portion 30 and the support portion 30 are used using a mask pattern (not shown) corresponding to the opening 10a of the fixing portion 10.
- the first silicon layer 51 located below the oscillator 20 is etched and removed. Further, the silicon oxide layer 52 is removed by etching using the same mask pattern to obtain the above-mentioned MEMS device.
- the etching of the first silicon layer 51 and the silicon oxide layer 52 may be dry etching or wet etching. However, in either case, it is preferable to use an etchant having high etching selectivity with the layer that is the base of the etching layer.
- FIG. 4 shows a schematic configuration diagram of a circuit block of an angular velocity sensor.
- the primary drive electrode PD and the secondary detection electrode SPO are simplified and shown in the vibration type gyro element 100.
- the angular velocity sensor 1000 has at least a vibration type gyro element 100, a primary AC power supply 200, a secondary detection unit 230, and a calculation unit 240.
- the primary AC power supply 200 is connected to the four primary drive electrodes PD.
- the secondary detection unit 230 is connected to the four secondary detection electrodes SPO connected in series. Further, the arithmetic unit 240 is connected to the secondary detection unit 230.
- the direction in which the magnetic field applied from the magnetic field application unit 60 to the primary drive electrode PD intersects with the direction in which the AC current Ip flows.
- Lorentz force is added to. That is, the Lorentz force acts in a direction parallel to the surface of the vibrator 20.
- the vibrator 20 provided with the primary drive electrode PD is deformed by receiving this Lorentz force.
- the oscillator 20 vibrates at the same frequency. In this case, the oscillator 20 vibrates in a direction parallel to its surface.
- the oscillator 20 is excited with the primary vibration in the cos2 ⁇ mode.
- the alternating currents Ip flowing through each of the four primary drive electrodes PD are alternately arranged in opposite directions.
- the primary drive electrode PD in which the alternating current Ip flows in the clockwise direction when viewed from above and the primary drive electrode PD in which the alternating current Ip flows in the counterclockwise direction are alternately arranged.
- the directions in which the alternating current Ip flows are opposite to each other between the two primary drive electrodes PD located 90 degrees apart in the circumferential direction, that is, the clockwise direction and the counterclockwise direction when viewed from above.
- connection relationship between the four primary drive electrodes PD and the primary AC power supply 200 may be such that the above-mentioned settings can be satisfied, and even if the four primary drive electrodes PD are connected in series, the primary AC power supply 200 may be connected. They may be connected in parallel.
- FIG. 5A schematically shows the primary vibration state of the vibrator
- FIG. 5B schematically shows the secondary vibration state of the vibrator.
- the annular oscillator 20 periodically vibrates in an elliptical shape having main axes orthogonal to each other.
- a Coriolis force is applied to the vibrator 20 and an angular velocity is generated in the axial direction
- the direction of the main axis of the ellipse described above changes.
- the main axis of the ellipse changes to a position rotated by 45 degrees with respect to the case of primary vibration, and the vibrator 20 is secondary. It becomes a vibration state.
- a magnetic field is also applied to the secondary detection electrode SPO in the direction intersecting its surface. Further, in response to the vibration of the vibrator 20, the secondary detection electrode SPO also vibrates in a direction parallel to the surface thereof. As a result, a voltage is generated in the secondary detection electrode SPO according to the strength of the magnetic field and the moving speed during vibration. Further, since the moving speed of the secondary detection electrode SPO is different between the case where the vibrator 20 is in the primary vibration state and the case where the vibrator 20 is in the secondary vibration state, the voltage generated in each state is also different.
- the secondary detection unit 230 detects the voltage generated in the secondary detection electrode SPO and outputs a signal corresponding to the magnitude of the voltage to the calculation unit 240.
- the arrangement orientation of the electrodes 40 is such that the motion axes assumed for each (hereinafter, may be referred to as the axes of the electrodes 40) are arranged at equal angular intervals in the outer peripheral direction of the vibrator 20. It can be said that there is.
- the calculation unit 240 determines whether the vibrator 20 is in the primary vibration state or the secondary vibration state based on the output signal of the secondary detection unit 230. Further, when it is determined that the vibrator 20 is in the secondary vibration state, the calculation unit 240 calculates the angular velocity based on the output signal of the secondary detection unit 230.
- the vibration type gyro element 100, the primary AC power supply 200, the secondary detection unit 230, and the calculation unit 240 may be mounted on different boards or may be mounted on the same board.
- the vibrating gyro element 100, the primary AC power supply 200, the secondary detection unit 230, and the calculation unit 240 may be housed in separate packages (not shown). Further, the vibrating gyro element 100 and other components may be mounted on another substrate or housed in another package. In that case, the primary AC power supply 200 may be mounted on yet another board or housed in another package.
- the vibration type gyro element 100 has a fixed portion 10, a vibrator 20, and a support in which the vibrator 20 is connected to the fixed portion 10 to vibrately support the vibrator 20.
- a portion 30 and electrodes 40a to 40h formed in a loop shape in the plane of the vibrator 20 are provided at least.
- the electrodes 40 are arranged in eight directions in which the axes of the electrodes 40 are equidistantly spaced in the outer peripheral direction of the vibrator 20, in this case, arranged at 45 degree intervals. Further, four primary drive electrodes PD and four secondary detection electrodes SPO are alternately arranged in eight directions.
- the vibration type gyro element 100 further includes a magnetic field application unit 60 that applies a magnetic field to the eight electrodes 40a to 40h in a direction intersecting the surface of the vibrator 20, in this case, an axial direction.
- FIG. 6 shows a crosstalk voltage generation location during operation of the vibrating gyro element of the present embodiment
- FIG. 7 shows a crosstalk voltage generation location during operation of the vibrating gyro element for comparison.
- the Roman numerals i to viii indicate the order of the directions in which the electrodes 40a to 40h are arranged.
- the order is determined in the clockwise direction. However, it may be determined in the counterclockwise direction. Further, it is possible to appropriately change which direction is the first direction.
- the arrow attached to the inside of the primary drive electrode PD indicates the direction in which the alternating current Ip flows.
- the white arrow attached to the inside of the secondary detection electrode SPO indicates the location where the crosstalk voltage is generated and the direction of the electromotive force thereof.
- the vibration type gyro element 110 shown in FIG. 7 has, for example, the same configuration as that disclosed in Patent Document 1. Further, the vibration type gyro element 110 is provided with two types of electrodes in addition to the primary drive electrode PD and the secondary detection electrode SPO. One type is a primary detection electrode (Primary Pickoff Electrode) PPO, which detects the primary vibration of the vibrator 20. The other type is a secondary driving electrode (Secondary Driving Electrode) SD, which drives the vibrator 20 so as to cancel the secondary vibration generated in the vibrator 20.
- Primary detection electrode Primary Pickoff Electrode
- secondary driving electrode Secondary Driving Electrode
- the primary drive electrode PD, the secondary drive electrode SD, the primary detection electrode PPO, and the secondary detection electrode SPO are arranged in this order in the clockwise direction when viewed from above in eight directions. Has been done. Further, two electrodes of each type are arranged, and the electrodes of the same type are arranged at positions 180 degrees apart in the circumferential direction.
- the primary drive electrode PD and the secondary detection electrode SPO are arranged adjacent to each other. Further, the directions of the alternating current Ip flowing through the two primary drive electrodes PD are the same, and in the example shown in FIG. 7, they are in the clockwise direction when viewed from above.
- the primary drive electrode PD is adjacently arranged on only one side, specifically, only on the clockwise side.
- the crosstalk voltage having a magnitude of Vspo generated in each of the two secondary detection electrodes SPO has the same direction of electromotive force (hereinafter, may be referred to as polarity). Therefore, when these two secondary detection electrodes SPO are connected in series, the crosstalk voltages generated by each do not cancel each other out, and the voltage detected by the secondary detection unit 230 has a magnitude of 2Vspo. The voltage is superimposed. This crosstalk voltage is superimposed on the output signal of the secondary detection unit 230 and the angular velocity calculated by the calculation unit 240 as an error.
- the amplitude of the alternating current Ip is set to a predetermined value or higher in order to cause the vibrator 20 to vibrate primary. Therefore, the magnitude 2Vspo of the crosstalk voltage also increases, and the error component of the angular velocity due to the crosstalk voltage cannot be ignored.
- the primary drive electrodes PD are adjacent to both sides of the secondary detection electrode SPO, that is, both clockwise and counterclockwise. Have been placed. Further, as described above, the directions of the alternating currents Ip flowing through the two primary drive electrodes PD adjacent to the secondary detection electrode SPO are opposite to each other. Therefore, in one secondary detection electrode SPO, the crosstalk voltage induced in the region where the primary drive electrode PD is adjacent to the clockwise side and the crosstalk voltage induced in the region where the primary drive electrode PD is adjacent to the counterclockwise side. The polarity is opposite to that of the crosstalk voltage. Therefore, these crosstalk voltages cancel each other out and cancel each other out.
- the magnitude of the crosstalk voltage induced in one secondary detection electrode SPO becomes almost zero. Since this applies to each of the four secondary detection electrodes SPO included in the vibrating gyro element 100, the magnitude of the crosstalk voltage generated in the vibrating gyro element 100 becomes almost zero. As a result, the output signal of the secondary detection unit 230 and, by extension, the error component superimposed on the angular velocity can be greatly reduced.
- the four secondary detection electrodes SPO are connected in series with each other.
- the voltage signals generated at each of the four secondary detection electrodes SPO are added, and a large voltage signal for detecting the secondary vibration can be obtained.
- the S / N ratio of the output signal of the secondary detection unit 230 can be increased, and the detection accuracy of the angular velocity calculated by the calculation unit 240 can be improved.
- the support portion 30 in which the electrode 40 is arranged has a first leg portion 31 having the first to third portions 31a, 31c, 31e and a second leg portion 31 having the first to third portions 32a, 32c, 32e, respectively. It is preferably composed of the legs 32. Further, it is more preferable that the first leg portion 31 and the second leg portion 32 are symmetrically arranged with respect to the virtual line passing between the center of the vibrator 20 and between the third portions 31e and 32e of each other.
- the support portion 30 By configuring the support portion 30 in this way, when the vibrator 20 is first vibrated, the vibrator 20 can be supported without significantly affecting the vibration. Further, the support portions 30 are provided at equal angular intervals in the circumferential direction, and the first leg portion 31 and the second leg portion 32 are provided symmetrically with respect to the above-mentioned virtual line, so that the vibrator 20 is evenly balanced. Can be connected to the fixed portion 10. As a result, the oscillator 20 can be stably subjected to primary vibration.
- the angular velocity sensor 1000 of the present embodiment detects a vibration type gyro element 100, a primary AC power supply 200 for passing an AC current of a predetermined frequency through the primary drive electrode PD, and a voltage signal generated in the secondary detection electrode SPO. It includes at least a secondary detection unit 230 and a calculation unit 240 that calculates an angular velocity based on the output signal of the secondary detection unit 230.
- the crosstalk voltage included in the output signal of the vibration type gyro element 100 can be reduced, and the detection accuracy of the angular velocity can be improved.
- FIGS. 8A to 8C and the drawings shown thereafter the same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.
- FIGS. 8A to 8C are different from the configurations shown in the first embodiment in that three primary drive electrodes PD are provided.
- the directions of the alternating current Ip flowing through each of the three primary drive electrodes PD are the same as those shown in FIG.
- the three primary drive electrodes PD and the four secondary detection electrodes SPO are arranged alternately in the circumferential direction.
- the secondary detection electrode SPO is arranged in the first, third, fifth, and seventh directions
- the primary drive electrode PD is arranged in the second, fourth, and sixth directions. ..
- the type of the electrode 40 for example, whether it is the primary drive electrode PD or the secondary detection electrode SPO, is not specified in the electrode 40h arranged in the eighth direction.
- the electrode 40h is a so-called dummy electrode provided for equalizing the mass balance of the vibrator 20, and does not contribute to the detection of the primary vibration and the secondary vibration of the vibrator 20.
- the electrode 40 whose type is not specified is also a dummy electrode.
- another function may be imparted to these dummy electrodes.
- the above-mentioned primary detection electrode PPO or secondary drive electrode SD may be used.
- the primary drive electrodes PD are arranged on both sides of the secondary detection electrodes SPO arranged in the third and fifth directions, respectively. Therefore, the crosstalk voltage induced in these two secondary detection electrodes SPO is almost zero.
- the primary drive electrode PD is arranged adjacent to the secondary detection electrode SPO arranged in the first direction on the clockwise side.
- the primary drive electrode PD is adjacent to the secondary detection electrode SPO arranged in the seventh direction on the counterclockwise side.
- the crosstalk voltages induced in these two secondary detection electrodes SPO are Vspo of the same magnitude, while the polarities are opposite to each other. Therefore, between the secondary detection electrodes SPO arranged in the first and seventh directions, the crosstalk voltages cancel each other out and become almost zero. That is, the crosstalk voltage is almost not included in the voltage generated in the four secondary detection electrodes SPO connected in series.
- three primary drive electrodes PD and three secondary detection electrodes SPO are provided.
- the secondary detection electrode SPO is arranged in the first, third, and seventh directions
- the primary drive electrode PD is arranged in the second, fourth, and sixth directions.
- the electrodes 40e and 40h arranged in the fifth and eighth directions are both dummy electrodes.
- the primary drive electrodes PD are arranged on both sides of the secondary detection electrode SPO arranged in the third direction. Therefore, the crosstalk voltage induced in this secondary detection electrode SPO is almost zero.
- the primary drive electrode PD is arranged adjacent to the secondary detection electrode SPO arranged in the first direction on the clockwise side.
- the primary drive electrode PD is adjacent to the secondary detection electrode SPO arranged in the seventh direction on the counterclockwise side.
- the crosstalk voltages induced in these two secondary detection electrodes SPO are Vspo of the same magnitude, while the polarities are opposite to each other. Therefore, between the secondary detection electrodes SPO arranged in the first and seventh directions, the crosstalk voltages cancel each other out and become almost zero. That is, the crosstalk voltage is almost not included in the voltage generated in the three secondary detection electrodes SPO connected in series.
- the number of the primary drive electrode PD and the secondary detection electrode SPO is the same as that shown in FIG. 8B.
- the secondary detection electrode SPO is arranged in the first, third, and fifth directions
- the primary drive electrode PD is arranged in the second, fourth, and sixth directions.
- the electrodes 40g and 40h arranged in the 7th and 8th directions are both dummy electrodes.
- the primary drive electrodes PD are arranged on both sides of the secondary detection electrodes SPO arranged in the third and fifth directions, respectively. Therefore, the crosstalk voltage induced in these two secondary detection electrodes SPO is almost zero.
- the primary drive electrode PD is arranged adjacent to the secondary detection electrode SPO arranged in the first direction on the clockwise side.
- the crosstalk voltage induced in the secondary detection electrode SPO arranged in the first direction does not become zero, and the voltage having a magnitude of Vspo remains. That is, the voltage generated in the three secondary detection electrodes SPO connected in series includes the crosstalk voltage having a magnitude of Vspo.
- FIG. 9A shows a plan view of the vibrating gyro element according to the present modification
- FIG. 9B shows a plan view of another vibrating gyro element.
- FIGS. 9A and 9B The configuration shown in FIGS. 9A and 9B is different from the configuration shown in the first embodiment in that two primary drive electrodes PD and two secondary detection electrodes SPO are provided.
- the direction of the alternating current Ip flowing through each of the two primary drive electrodes PD is the same as that shown in FIG.
- two sets of electrodes 40 in which the primary drive electrode PD and the secondary detection electrode SPO are adjacent to each other are arranged in the circumferential direction.
- the secondary detection electrode SPO is arranged in the first and fifth directions
- the primary drive electrode PD is arranged in the second and fourth directions.
- the electrodes 40c, 40f, 40g, and 40h arranged in the third and sixth to eighth directions, respectively, are dummy electrodes.
- the primary drive electrode PD is arranged adjacent to the secondary detection electrode SPO arranged in the first direction on the clockwise side.
- the primary drive electrode PD is adjacent to the secondary detection electrode SPO arranged in the fifth direction on the counterclockwise side.
- the crosstalk voltages induced in these two secondary detection electrodes SPO are Vspo having the same magnitude, while the polarities are opposite to each other. Therefore, between the secondary detection electrodes SPO arranged in the first and fifth directions, the crosstalk voltages cancel each other out and become almost zero. That is, the crosstalk voltage is almost not included in the voltage generated in the two secondary detection electrodes SPO connected in series.
- the secondary detection electrode SPO is arranged in the third and seventh directions, and the primary drive electrode PD is arranged in the second and fourth directions.
- the electrodes 40a, 40e, 40f, and 40h arranged in the first, fifth, sixth, and eighth directions, respectively, are dummy electrodes.
- the primary drive electrodes PD are arranged on both sides of the secondary detection electrode SPO arranged in the third direction. Therefore, the crosstalk voltage induced in this secondary detection electrode SPO is almost zero.
- the primary drive electrodes PD are not arranged adjacent to the secondary detection electrode SPO arranged in the seventh direction on both sides. Therefore, the crosstalk voltage induced in this secondary detection electrode SPO is also almost zero. That is, the crosstalk voltage is almost not included in the voltage generated in the two secondary detection electrodes SPO connected in series.
- FIG. 10A shows a plan view of the vibrating gyro element according to the present modification
- FIG. 10B shows a plan view of another vibrating gyro element.
- FIGS. 10A and 10B are provided with two primary drive electrodes PD and two secondary detection electrodes SPO, as in the configuration shown in the second modification.
- the direction of the alternating current Ip flowing through each of the two primary drive electrodes PD is the same as that shown in FIG.
- two sets of electrodes in which the primary drive electrode PD and the secondary detection electrode SPO are adjacent to each other are arranged in the circumferential direction.
- the secondary detection electrode SPO is arranged in the first and seventh directions
- the primary drive electrode PD is arranged in the second and sixth directions.
- the electrodes 40c, 40d, 40e, and 40h arranged in the third to fifth and eighth directions, respectively, are dummy electrodes.
- the primary drive electrode PD is arranged adjacent to the secondary detection electrode SPO arranged in the first direction on the clockwise side.
- the primary drive electrode PD is adjacent to the secondary detection electrode SPO arranged in the seventh direction on the counterclockwise side.
- the crosstalk voltages induced in these two secondary detection electrodes SPO are Vspo having the same magnitude, while the polarities are opposite to each other. Therefore, between the secondary detection electrodes SPO arranged in the first and seventh directions, the crosstalk voltages cancel each other out and become almost zero. That is, the crosstalk voltage is almost not included in the voltage generated in the two secondary detection electrodes SPO connected in series.
- the secondary detection electrode SPO is arranged in the first and third directions, and the primary drive electrode PD is arranged in the second and sixth directions.
- the electrodes 40d, 40e, 40g, and 40h arranged in the fourth, fifth, seventh, and eighth directions, respectively, are dummy electrodes.
- the primary drive electrode PD is arranged adjacent to the secondary detection electrode SPO arranged in the first direction on the clockwise side.
- the primary drive electrode PD is adjacent to the secondary detection electrode SPO arranged in the third direction on the counterclockwise side.
- the crosstalk voltages induced in these two secondary detection electrodes SPO are Vspo having the same magnitude, while the polarities are opposite to each other. Therefore, between the secondary detection electrodes SPO arranged in the first and third directions, the crosstalk voltages cancel each other out and become almost zero. That is, the crosstalk voltage is almost not included in the voltage generated in the two secondary detection electrodes SPO connected in series.
- FIG. 11A shows a plan view of the vibrating gyro element according to the present modification
- FIG. 11B shows a plan view of another vibrating gyro element.
- FIGS. 11A and 11B are provided with two primary drive electrodes PD and two secondary detection electrodes SPO, as in the configuration shown in the second modification.
- the direction of the alternating current Ip flowing through each of the two primary drive electrodes PD is the same as that shown in FIG.
- the secondary detection electrode SPO is arranged in the first and seventh directions, and the primary drive electrode PD is arranged in the second and fourth directions.
- the electrodes 40c, 40e, 40f, and 40h arranged in the third, fifth, sixth, and eighth directions, respectively, are dummy electrodes.
- the primary drive electrodes PD are not arranged adjacent to the secondary detection electrode SPO arranged in the 7th direction on both sides. Therefore, the crosstalk voltage induced in this secondary detection electrode SPO is almost zero.
- the primary drive electrode PD is arranged adjacent to the secondary detection electrode SPO arranged in the first direction on the clockwise side.
- the crosstalk voltage induced in the secondary detection electrode SPO arranged in the first direction does not become zero, and the voltage having a magnitude of Vspo remains. That is, the voltage generated in the two secondary detection electrodes SPO connected in series includes the crosstalk voltage having a magnitude of Vspo.
- the secondary detection electrode SPO is arranged in the first and third directions, and the primary drive electrode PD is arranged in the second and fourth directions.
- the electrodes 40e, 40f, 40g, and 40h arranged in the 5th to 8th directions, respectively, are dummy electrodes.
- the primary drive electrodes PD are arranged on both sides of the secondary detection electrode SPO arranged in the third direction. Therefore, the crosstalk voltage induced in this secondary detection electrode SPO is almost zero.
- the primary drive electrode PD is arranged adjacent to the secondary detection electrode SPO arranged in the first direction on the clockwise side.
- the crosstalk voltage induced in the secondary detection electrode SPO arranged in the first direction does not become zero, and the voltage having a magnitude of Vspo remains. That is, the voltage generated in the two secondary detection electrodes SPO connected in series includes the crosstalk voltage having a magnitude of Vspo.
- FIG. 12A shows a plan view of the vibrating gyro element according to the present modification
- FIG. 12B shows a plan view of another vibrating gyro element.
- FIGS. 12A and 12B are provided with two primary drive electrodes PD and two secondary detection electrodes SPO, as in the configuration shown in the second modification.
- the direction of the alternating current Ip flowing through each of the two primary drive electrodes PD is the same as that shown in FIG.
- the secondary detection electrode SPO is arranged in the first and fifth directions, and the primary drive electrode PD is arranged in the third and seventh directions.
- the electrodes 40b, 40d, 40f, and 40h arranged in the second, fourth, sixth, and eighth directions, respectively, are dummy electrodes.
- the two primary drive electrodes PD are arranged at positions 180 degrees apart from each other in the circumferential direction.
- the two secondary detection electrodes SPO are arranged at positions 180 degrees apart from each other in the circumferential direction.
- the secondary detection electrode SPO is arranged at a position 90 degrees away from the primary drive electrode PD in the circumferential direction.
- the primary drive electrodes PD are not arranged adjacent to each other on both sides of any of the secondary detection electrodes SPO arranged in the first and fifth directions. Therefore, the crosstalk voltage induced in this secondary detection electrode SPO is almost zero. That is, the crosstalk voltage is almost not included in the voltage generated in the two secondary detection electrodes SPO connected in series.
- the secondary detection electrode SPO is arranged in the first and third directions, and the primary drive electrode PD is arranged in the fifth and seventh directions.
- the electrodes 40b, 40d, 40f, and 40h arranged in the second, fourth, sixth, and eighth directions, respectively, are dummy electrodes.
- the two primary drive electrodes PD are arranged at positions 90 degrees apart in the circumferential direction.
- the two secondary detection electrodes SPO are arranged 90 degrees apart in the circumferential direction.
- the primary drive electrode PD and the secondary detection electrode SPO face each other and are arranged at positions 180 degrees apart in the circumferential direction.
- the primary drive electrodes PD are not arranged adjacent to each other on both sides of any of the secondary detection electrodes SPO arranged in the first and third directions. Therefore, the crosstalk voltage induced in this secondary detection electrode SPO is almost zero. That is, the crosstalk voltage is almost not included in the voltage generated in the two secondary detection electrodes SPO connected in series.
- the vibrator 20 can take a vibration mode of cosN ⁇ (N is a natural number of 2 or more).
- N is a natural number of 2 or more.
- the number of arrangement orientations assigned to each electrode 40 is 4N.
- S1 is the number when the primary drive electrode PD is arranged in the direction adjacent to the clockwise side with respect to the secondary detection electrode SPO.
- S2 is the number when the primary drive electrode PD is arranged in the direction adjacent to the counterclockwise side with respect to the secondary detection electrode SPO. In the following description, it may be simply referred to as a case number S1 and a case number S2.
- U is the number of secondary detection electrodes SPO in which the primary drive electrode PD is not arranged in either the direction adjacent to the clockwise side or the direction adjacent to the counterclockwise side.
- both the numbers S1 and S2 in the case are counted as "1".
- the number S1 in the case is "1”.
- the number S2 in the case is also "1".
- the secondary detection electrode SPO in which the primary drive electrode PD is not arranged in either the direction adjacent to the clockwise side or the direction adjacent to the counterclockwise side is used. No crosstalk voltage is generated. That is, if one or more of the plurality of secondary detection electrode SPOs included in the vibration type gyro element 100 have one or more secondary detection electrode SPOs that meet this condition, the total crosstalk voltage is reduced. That is, if the above equation (1) is satisfied, the crosstalk voltage included in the total voltage generated by the secondary detection electrode SPO is reduced.
- the voltages generated by each of the plurality of secondary detection electrodes SPO are added. Therefore, when the primary drive electrode PD is arranged in the direction adjacent to the clockwise side with respect to the secondary detection electrode SPO, the crosstalk voltage generated at the secondary detection electrode SPO and the counterclockwise side are adjacent to each other. When arranged in the orientation, the sum of the crosstalk voltage and the crosstalk voltage of the secondary detection electrode SPO is the sum of the crosstalk voltages included in the total voltage generated by the secondary detection electrode SPO.
- (S1 + S2) corresponds to the maximum value of the crosstalk voltage included in the total voltage generated by the secondary detection electrode SPO.
- ((S1 + S2) -2) shown in the equation (2) when the crosstalk voltage is offset once, that is, there is one set of secondary detection electrodes SPO in which the crosstalk voltage is offset.
- ((S1 + S2) -2) shown in Eq. (2) is the total voltage generated by the secondary detection electrode SPO when one offset occurs and the crosstalk voltage is reduced. It corresponds to the magnitude of the included crosstalk voltage.
- the equation (2) means that in a plurality of secondary detection electrode SPOs, there is one or more secondary detection electrode SPOs in which the crosstalk voltage is offset. .. That is, if the above equation (2) is satisfied, the crosstalk voltage included in the total voltage generated by the secondary detection electrode SPO is reduced.
- FIG. 13 shows the relationship between the arrangement of the primary drive electrode and the secondary detection electrode and the crosstalk voltage reduction condition.
- vibration type gyro element 100 shown in the first embodiment and the modified examples 1 to 5 is arranged, the following can be said about the arrangement relationship of the primary drive electrode PD and the secondary detection electrode SPO.
- the electrodes 40 arranged in the first direction and the Kth direction are either the primary drive electrode PD or the primary drive electrode PD. , Secondary detection electrode SPO.
- the electrodes 40 from the first to the Kth there is at least one region in which the primary drive electrode PD and the secondary detection electrode SPO are alternately arranged adjacent to each other in both the clockwise and counterclockwise directions. The above is provided.
- Condition A means that there is one or more secondary detection electrodes SPO whose crosstalk voltage is offset. Therefore, it is clear that if this condition is satisfied, the relationship shown in the above equation (2) is satisfied.
- FIGS. 6, 8A to 8C, 9A, 10A, 10B and 11B satisfy the condition A.
- FIG. 9B assuming that the orientation of the primary drive electrode PD adjacent to the secondary detection electrode SPO located in the original first orientation shown in FIG. 6 in the counterclockwise direction is the first, FIG. 9B The configuration shown in 1 also satisfies the condition A.
- the arrangement relationship between the primary drive electrode PD and the secondary detection electrode SPO that satisfy the condition A is further classified as follows. However, there may be an arrangement relationship between the primary drive electrode PD and the secondary detection electrode SPO that satisfy both the conditions A1 and A2.
- the primary drive electrode PD and the secondary detection electrode SPO are adjacent to each other.
- the secondary detection electrodes SPO included in each set are arranged in directions separated from each other by (360 / 2N + 360 ⁇ (M / 2N)) degrees, and the primary drive electrodes PD are arranged (360 / N + 360 ⁇ ) from each other. They are arranged at (M / 2N)) degrees or (360 ⁇ (M / 2N)) degrees away (see FIGS. 8A, 8B, 10A).
- the secondary detection electrodes SPO are arranged in different directions in an angle range larger than 0 degrees and less than 360 degrees.
- the primary drive electrodes PD are arranged in different directions in an angle range larger than 0 degrees and less than 360 degrees.
- M is an integer of 0 or more.
- the primary drive electrode PD and the secondary detection electrode SPO are adjacent to each other. Further, in this case, the primary drive electrodes PD included in each set are arranged in directions separated from each other by (360 / 2N + 360 ⁇ (M / 2N)) degrees, and the secondary detection electrodes SPO are arranged at a distance of (360 / N + 360 ⁇ ) from each other. It is arranged in an orientation separated by (M / 2N)) degrees or (360 ⁇ (M / 2N)) degrees (see FIG. 9A). However, the primary drive electrodes PD are arranged in different directions in an angle range larger than 0 degrees and less than 360 degrees. Similarly, the secondary detection electrodes SPOs are arranged in different directions in an angle range larger than 0 degrees and less than 360 degrees.
- the primary drive electrode PD is arranged in both the direction adjacent to the clockwise side and the direction adjacent to the counterclockwise side. (See FIGS. 6, 8A-8C, 9B, 11B).
- FIG. 14 shows a plan view of the vibration type gyro element according to the present embodiment
- FIG. 15 shows an enlarged view of a portion surrounded by a broken line in FIG.
- FIG. 16 shows a schematic configuration diagram of a circuit block of an angular velocity sensor.
- FIG. 16 as in FIG. 4, only the electrodes PD, PPO, SD, and SPO of the vibration type gyro element 120 are shown in a simplified manner.
- the vibration type gyro element 120 of the present embodiment shown in FIGS. 14 and 15 is different from the vibration type gyro element 100 shown in the first embodiment in that the above-mentioned secondary drive electrode SD and the primary detection electrode PPO are provided.
- the number and arrangement orientation of the primary drive electrode PD and the secondary detection electrode SPO are the same as those shown in the first embodiment. Therefore, the vibration type gyro element 120 has 16 electrodes 40a to 40p.
- the primary detection electrode PPO is arranged in the same direction as the primary drive electrode PD, and the secondary drive electrode SD is arranged in the same direction as the secondary detection electrode SPO. This point will be further described.
- two electrodes 40d and 40l are formed so as to extend in parallel with a space between them in the plane of the support portion 30 and the vibrator 20.
- the two electrodes 40e and 40m are formed so as to extend in parallel with a distance from each other in the plane of the support portion 30 and the vibrator 20.
- parallel is not only when the two members are arranged in parallel with each other, but also when the two members are arranged at intervals to the extent that they do not come into contact with each other or intersect with each other. It is also included if it is.
- the electrode 40d arranged on the outside is the primary drive electrode PD and the electrode 40l arranged on the inside. Is the primary detection electrode PPO.
- the electrode 40e arranged on the outside is the secondary drive electrode SD, and the electrode 40m arranged on the inside is.
- the secondary detection electrode SPO is provided in this vibration type gyro element 120, the same number of sets of the primary drive electrode PD and the primary detection electrode PPO and the set of the secondary drive electrode SD and the secondary detection electrode SPO are provided.
- the angular velocity sensor 1100 of the present embodiment shown in FIG. 16 is different from the angular velocity sensor 1000 shown in the first embodiment in that it further has a primary detection unit 210 and a secondary AC power supply 220. That is, the angular velocity sensor 1100 of the present embodiment has at least a vibration type gyro element 120, a primary AC power supply 200, a primary detection unit 210, a secondary AC power supply 220, a secondary detection unit 230, and a calculation unit 240.
- the primary AC power supply 200 is connected to the four primary drive electrodes PD.
- the primary detection unit 210 is connected to the four primary detection electrodes PPO connected in series.
- the secondary AC power supply 220 is connected to the four secondary drive electrodes SD.
- the secondary detection unit 230 is connected to the four secondary detection electrodes SPO connected in series. Further, the arithmetic unit 240 is connected to the secondary AC power supply 220.
- the secondary detection electrode SPO When an alternating current Ip is passed through the primary drive electrode PD to excite the oscillator 20 to excite the primary vibration in cos2 ⁇ mode, and when an angular velocity is generated in the oscillator 20 to cause secondary vibration, the secondary detection electrode SPO is used. It is the same as the first embodiment that a voltage signal having a magnitude corresponding to the secondary vibration is generated.
- the primary detection electrode PPO detects the primary vibration and generates a voltage signal having a magnitude corresponding to the amplitude of the primary vibration, and this voltage signal is fed back to the primary detection unit 210.
- the primary detection unit 210 outputs an output signal to the primary AC power supply 200 based on the voltage signal generated by the primary detection electrode PPO. Based on the output signal of the primary detection unit 210, the amplitude and frequency of the primary AC power supply 200, specifically, the AC current Ip are controlled so that the vibration frequency and the amplitude of the vibrator 20 are constant.
- the output signal of the secondary detection unit 230 is input to the secondary AC power supply 220. Based on this output signal, the secondary AC power supply 220 supplies an alternating current to the secondary drive electrode SD so as to cancel the secondary vibration generated in the oscillator 20, and drives the oscillator 20. Further, the secondary AC power supply 220 inputs an output signal based on the output current to the calculation unit 240.
- the calculation unit 240 calculates the angular velocity based on the output signal of the secondary AC power supply 220.
- the voltage generated by the primary detection electrode PPO is detected by the primary detection unit 210, and the output signal of the primary detection unit 210 is fed back to the primary AC power supply 200, so that the primary generated by the vibrator 20 is generated. Vibration can be stabilized.
- the voltage generated by the secondary detection electrode SPO is detected by the secondary detection unit 230, the output of the secondary AC power supply 220 is controlled based on the output signal of the secondary detection unit 230, and the voltage is generated by the vibrator 20. I try to cancel the secondary vibration. By doing so, the vibration state of the vibrator 20 can be stabilized. Further, by this, the noise component included in the output signal of the secondary AC power supply 220 can be reduced, and the detection accuracy of the angular velocity can be improved.
- the vibration type gyro element 120 of the present embodiment has the same arrangement and connection relationship between the primary drive electrode PD and the secondary detection electrode SPO as the vibration type gyro element 100 shown in the first embodiment. That is, even in the vibration type gyro element 120 and the angular velocity sensor 1100 of the present embodiment, the same effect as that of the configuration shown in the first embodiment can be obtained. That is, it is possible to reduce the crosstalk voltage included in the voltage generated by the secondary detection electrode SPO during the operation of the vibration type gyro element 120. Further, the crosstalk voltage included in the output signal of the vibration type gyro element 120 can be reduced, and the detection accuracy of the angular velocity can be improved.
- the azimuth is located between the azimuth in which the primary drive electrode PD is arranged and the azimuth in which the secondary detection electrode SPO is arranged.
- the next drive electrode SD is arranged.
- the arrangement of the electrodes PD, PPO, SD, and SPO provided on each support portion 30 is not particularly limited to the examples shown in FIGS. 14 and 15.
- the primary detection electrode PPO may be arranged on the outside and the primary drive electrode PD may be arranged on the inside.
- the primary detection electrode PPO and the secondary drive electrode SD are arranged between the primary drive electrode PD and the secondary detection electrode SPO, and the magnitude of the crosstalk voltage generated in the secondary detection electrode SPO is large. Can be further reduced.
- the S / N ratio of the output signal of the secondary detection unit 230 can be increased, and the detection accuracy of the angular velocity calculated by the calculation unit 240 can be improved. It is the same as shown in Embodiment 1.
- the four primary detection electrodes PPO are connected in series.
- the primary detection electrode PPO and the secondary drive electrode SD shown in the second embodiment may be applied to the vibration type gyro element 100 shown in the modified examples 1 to 5.
- the primary drive electrode PD and the primary detection electrode PPO are formed so as to extend in parallel at intervals from each other in the planes of the support portion 30 and the oscillator 20.
- the secondary drive electrode SD and the secondary detection electrode SPO are formed so as to extend in parallel at intervals from each other in the planes of the support portion 30 and the oscillator 20.
- the primary drive electrode PD and the primary detection electrode PPO are arranged in parallel on the surfaces of the oscillator 20 and the support portion 30.
- the present invention is not particularly limited to this, and for example, the oscillator 20 and the support portion 30 may be arranged in parallel at intervals in the thickness direction.
- one of the primary drive electrode PD and the primary detection electrode PPO may be provided on the front surface of the oscillator 20 and the support portion 30, and the other may be provided on the back surface of the oscillator 20 and the support portion 30.
- the secondary drive electrode SD and the secondary detection electrode SPO may be arranged in parallel at intervals in the thickness direction of the oscillator 20 and the support portion 30.
- one of the secondary drive electrode SD and the secondary detection electrode SPO may be provided on the front surface of the oscillator 20 and the support portion 30, and the other may be provided on the back surface of the oscillator 20 and the support portion 30.
- these electrodes may be arranged inside the oscillator 20 and the support portion 30.
- the oscillator 20 may have a shape in which the vibration state changes when the primary vibration is excited and an angular velocity is generated, and the vibrator 20 is not particularly limited to an annular shape.
- the vibrator 20 may be a regular polygonal ring shape or a disk-shaped shape. Further, it may have a hemispherical shape.
- the support portion 30 only needs to be able to connect the vibrator 20 to the fixed portion 10 without disturbing the vibration of the vibrator 20, and the shape thereof is not limited to the shapes shown in FIGS. 1 and 3.
- the voltage generated by each of the plurality of secondary detection electrodes SPO may be input to the calculation unit 240 and the addition process may be performed inside the calculation unit 240 without connecting the plurality of secondary detection electrodes SPO in series.
- the voltage generated by each is input to the calculation unit 240 (not shown), the addition process is performed inside the calculation unit 240, and the voltage is input to the primary AC power supply 200. You may try to do it.
- the crosstalk voltage generated in the secondary detection electrode during operation can be reduced, which is useful for application to a high-precision angular velocity sensor.
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Abstract
Description
[振動型ジャイロ素子の構成]
図1は、本実施形態1に係る振動型ジャイロ素子の平面図を、図2は、図1のII-II線での断面図を、図3は、図1の破線で囲まれた部分の拡大図をそれぞれ示す。
図4は、角速度センサの回路ブロックの概略構成図を示す。なお、説明の便宜上、図4において、振動型ジャイロ素子100のうち、一次駆動電極PDと二次検出電極SPOのみを簡略化して図示している。
以上説明したように、本実施形態に係る振動型ジャイロ素子100は、固定部10と、振動子20と、振動子20を固定部10に接続して、振動子20を振動可能に支持する支持部30と、振動子20の面内にそれぞれループ状に形成された電極40a~40hと、を少なくとも備えている。
図8Aは、本変形例に係る振動型ジャイロ素子の平面図を、図8Bは、別の振動型ジャイロ素子の平面図を、図8Cは、さらなる別の振動型ジャイロ素子の平面図をそれぞれ示す。なお、図8A~8C及び以降に示す各図面において、実施形態1と同様の箇所については、同一の符号を付して詳細な説明を省略する。
図9Aは、本変形例に係る振動型ジャイロ素子の平面図を、図9Bは、別の振動型ジャイロ素子の平面図をそれぞれ示す。
図10Aは、本変形例に係る振動型ジャイロ素子の平面図を、図10Bは、別の振動型ジャイロ素子の平面図をそれぞれ示す。
図11Aは、本変形例に係る振動型ジャイロ素子の平面図を、図11Bは、別の振動型ジャイロ素子の平面図をそれぞれ示す。
図12Aは、本変形例に係る振動型ジャイロ素子の平面図を、図12Bは、別の振動型ジャイロ素子の平面図をそれぞれ示す。
一次駆動電極PDの配置方位や個数によっては、振動子20は、cosNθ(Nは2以上の自然数)の振動モードを取りうる。この場合、各電極40に割り当てられる配置方位は4N個となる。実施形態1及び変形例1~5に示す例は、いずれもN=2の場合に相当する。
(S1+S2)-2≧|S1-S2| ・・・(2)
1番目からK番目(Kは奇数でかつ3≦K≦4N-1)まで連続した方位において、1番目の方位とK番目の方位とに配置される電極40が、一次駆動電極PDか、または、二次検出電極SPOのいずれかである。1番目からK番目までの電極40において、一次駆動電極PDと二次検出電極SPOとが交互に隣接して配置される領域が、時計回り方向及び反時計回り方向のいずれからみても少なくとも1つ以上設けられている。
以下の条件を満たす一次駆動電極PDと片側のみに隣接する二次検出電極SPOの組が2組以上存在する。まず、当該電極の組において、一次駆動電極PDと二次検出電極SPOとが隣接している。また、この場合、各組に含まれる二次検出電極SPOは、互いに(360/2N+360×(M/2N))度離れた方位に配置され、かつ一次駆動電極PDは、互いに(360/N+360×(M/2N))度または(360×(M/2N))度離れた方位に配置されている(図8A、8B、図10A参照)。ただし、二次検出電極SPO間は、0度よりも大きく360度未満となる角度範囲で離れた方位に配置されている。同様に、一次駆動電極PD間は、0度よりも大きく360度未満となる角度範囲で離れた方位に配置されている。なお、ここで、Mは0以上の整数である。
以下の条件を満たす一次駆動電極PDと片側のみに隣接する二次検出電極SPOの組が2組以上存在する。まず、当該電極の組において、一次駆動電極PDと二次検出電極SPOとが隣接している。また、この場合、各組に含まれる一次駆動電極PDは、互いに(360/2N+360×(M/2N))度離れた方位に配置され、かつ二次検出電極SPOは、互いに(360/N+360×(M/2N))度または(360×(M/2N))度離れた方位に配置されている(図9A参照)。ただし、一次駆動電極PD間は、0度よりも大きく360度未満となる角度範囲で離れた方位に配置されている。同様に、二次検出電極SPO間は、0度よりも大きく360度未満となる角度範囲で離れた方位に配置されている。
少なくとも1つの二次検出電極SPOに対して、一次駆動電極PDが時計回り側に隣接する方位及び反時計回り側に隣接する方位のいずれにも配置される。(図6、図8A~8C、図9B、図11B参照)。なお、図6に示す例は、N=2の場合であって、4N個の方位に対して、2N個の一次駆動電極PDと2N個の二次検出電極SPOが交互に配置された例である。
図14は、本実施形態に係る振動型ジャイロ素子の平面図を示し、図15は、図14の破線で囲まれた部分の拡大図を示す。図16は、角速度センサの回路ブロックの概略構成図を示す。なお、説明の便宜上、図4と同様に、図16においても、振動型ジャイロ素子120のうち、電極PD,PPO,SD,SPOのみを簡略化して図示している。
実施形態1,2及び各変形例に示した各構成要素を適宜組み合わせて、新たな実施形態とすることもできる。
20 振動子
30 支持部
40a~40p 電極
51 第1シリコン層
52 シリコン酸化層
53 第2シリコン層
54 シリコン酸化膜
60 磁場印加部
61 上部ヨーク
62 磁石
63 下部ヨーク
100,110,120 振動型ジャイロ素子
200 一次交流電源
210 一次検出部
220 二次交流電源
230 二次検出部
240 演算部
1000 角速度センサ
1100 角速度センサ
Claims (7)
- 固定部と、
振動子と、
前記振動子を前記固定部に接続して、前記振動子を振動可能に支持する支持部と、
前記振動子の面内に形成された電極と、を少なくとも備え、
前記振動子がcosNθ(Nは2以上の自然数)の振動モードを有するとき、
前記振動子の外周方向に前記電極の軸が等角度間隔に並ぶ4N個の方位に前記電極がそれぞれ配置されており、
複数の前記電極には、前記振動子にcosNθモードの一次振動を励起させる一次駆動電極と、前記振動子の二次振動を検出する二次検出電極とがそれぞれ含まれており、
前記二次検出電極に対して前記一次駆動電極が時計回り側に隣接した方位に配置される場合の数をS1とし、前記二次検出電極に対して前記一次駆動電極が反時計回り側に隣接した方位に配置される場合の数をS2とし、前記一次駆動電極が時計回り側に隣接する方位及び反時計回り側に隣接する方位のいずれにも配置されない前記二次検出電極の個数をUと、それぞれするとき、
U≧1 (1)
または、
(S1+S2)-2≧|S1-S2| (2)
の関係を満たす、振動型ジャイロ素子。 - S1=S2の関係を満たす、請求項1に記載の振動型ジャイロ素子。
- 複数の前記電極に対して、前記振動子の表面と交差する方向に磁場を印加する磁場印加部をさらに備えた、請求項1または2に記載の振動型ジャイロ素子。
- 複数の前記電極は、
前記一次振動を検出する一次検出電極と、
前記二次振動を打ち消すように前記振動子を駆動する二次駆動電極と、をさらに含み、
前記一次検出電極は、前記一次駆動電極と同じ方位に配置され、
前記二次駆動電極は、前記二次検出電極と同じ方位に配置される、請求項1ないし3のいずれか1項に記載の振動型ジャイロ素子。 - 請求項1ないし3のいずれか1項に記載の振動型ジャイロ素子と、
前記一次駆動電極に所定の周波数の交流電流を印加する一次交流電源と、
前記二次検出電極に発生する電圧信号を検出する二次検出部と、
前記二次検出部の出力信号に基づいて、角速度を算出する演算部と、を少なくとも備えた角速度センサ。 - 請求項4に記載の振動型ジャイロ素子と、
前記一次駆動電極に所定の周波数の交流電流を印加する一次交流電源と、
前記一次検出電極に発生する電圧信号を検出する一次検出部と、
前記二次駆動電極に交流電流を印加する二次交流電源と、
前記二次検出電極に発生する電圧信号を検出する二次検出部と、
前記二次交流電源の出力信号に基づいて、角速度を算出する演算部と、を少なくとも備えた角速度センサ。 - 前記一次検出部の出力信号を前記一次交流電源にフィードバックすることで、前記振動子で発生する前記一次振動を安定化させ、
前記二次検出部の出力信号に基づいて、前記振動子で発生する前記二次振動を打ち消すように前記二次交流電源の出力を制御し、
前記演算部は、前記二次交流電源の出力信号に基づいて、角速度を算出する、請求項6に記載の角速度センサ。
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