Vibratory gyroscope element and angular rate sensor comprising the same

Abstract

A vibration type gyro element (100) includes a fixed portion (10), a vibrator (20) having a vibration mode of cosNθ (N is a natural number of 2 or more), a support portion (30), and electrodes (40). The electrodes (40) are arranged in 4N azimuths arranged in an outer peripheral direction of the vibrator (20), respectively. The plurality of electrodes (40) include a primary drive electrode (PD), a primary detection electrode (PPO), a secondary detection electrode (SPO), and a secondary drive electrode (SD). The primary detection electrode (PPO) and the primary drive electrode (PD) are arranged in the same azimuth, and the secondary drive electrode (SD) and the secondary detection electrode (SPO) are arranged in the same azimuth.

Description

Technical Field

[0001] This disclosure relates to a vibrating gyroscope element and an angular velocity sensor including the vibrating gyroscope element. Background Technology

[0002] To date, oscillating gyroscopes have been known as gyroscope elements for use in angular velocity sensors. For example, electromagnetic gyroscopes with multiple electrodes arranged on the front of a ring oscillator and a magnetic field applied along the direction intersecting the front of the electrodes are well known (see, for example, Patent Documents 1 and 2).

[0003] In an electromagnetic gyroscope element, when a magnetic field is applied, a current with a frequency equivalent to the resonant frequency of the oscillator flows to a portion of the electrodes (hereinafter referred to as the primary driving electrode) to cause the oscillator to resonate (hereinafter referred to as primary vibration). When an angular velocity is generated by applying a Coriolis force to the oscillator, the voltage generated on the other electrode (hereinafter referred to as the secondary pickoff electrode) is detected and used as a signal for calculating the angular velocity. It should be noted that, in most cases, an electrode is provided for detecting the primary vibration and stabilizing the amplitude and frequency of the primary vibration (hereinafter referred to as the primary pickoff electrode), and an electrode is provided for driving the oscillator 20 according to the signal detected by the secondary pickoff electrode to cancel the secondary vibration (hereinafter referred to as the secondary driving electrode).

[0004] On the other hand, in angular velocity sensors with vibrating gyroscope elements, a bias component is sometimes superimposed on the output signal. The bias component, also known as zero-point output or bias, is caused by angular deviations between multiple electrodes on the vibrating gyroscope element, and / or by non-uniformity of the applied magnetic field in the case of an electromagnetic gyroscope element.

[0005] To remove this bias component, for example, Patent Document 3 discloses a structure in which drive control is performed by periodically switching between a primary drive electrode and a primary detection electrode (hereinafter, sometimes referred to as the primary side) and a secondary drive electrode and a secondary detection electrode (hereinafter, sometimes referred to as the secondary side). In this case, the bias component is eliminated by removing the difference between the output signals before and after the switching.

[0006] Patent Document 1: Japanese Patent No. 5410518

[0007] Patent Document 2: Japanese Patent Publication No. 2019-032302

[0008] Patent Document 3: Japanese Patent Publication No. 2009-115559 Summary of the Invention

[0009] -The technical problem the invention aims to solve-

[0010] However, the aforementioned angular deviation is mainly caused by mask misalignment or deformation of the resist pattern during the manufacturing of the gyroscope element. For each of the multiple electrodes, the angular deviation is generally asymmetrical.

[0011] Therefore, even when using the method disclosed in Patent Document 3, an unavoidable bias component remains in the output signal, causing errors in the detected angular velocity. This residual bias component is particularly problematic when high-precision angular velocity determination is required.

[0012] This disclosure was made in view of the above-mentioned technical problems, and its object is to provide a vibrating gyroscope element capable of reducing the bias component contained in the output signal, and an angular velocity sensor including the vibrating gyroscope element.

[0013] - Technical solutions for solving technical problems -

[0014] To achieve the above objectives, the vibration-type gyroscope element disclosed herein includes at least a fixed part, an oscillator, a support part, and electrodes. The support part connects the oscillator to the fixed part and supports the oscillator in a manner that allows the oscillator to vibrate. The electrodes are formed in the plane of the oscillator. When the oscillator has a vibration mode of cosNθ (N is a natural number greater than 2), the electrodes are arranged in 4N directions. In these 4N directions, the axes of the electrodes are arranged at equal angular intervals in the outer circumferential direction of the oscillator. The plurality of electrodes include a primary driving electrode, a primary detection electrode, a secondary detection electrode, and a secondary driving electrode. The primary driving electrode excites a primary vibration of the cosNθ mode on the oscillator. The primary detection electrode detects the primary vibration. The secondary detection electrode detects the secondary vibration of the oscillator. The secondary driving electrode drives the oscillator to counteract the secondary vibration. The primary detection electrode and the primary driving electrode are arranged in the same direction, and the secondary driving electrode and the secondary detection electrode are arranged in the same direction.

[0015] The angular velocity sensor disclosed herein includes at least the aforementioned vibrating gyroscope element, a primary AC power supply, a primary detection unit, a secondary AC power supply, a secondary detection unit, and a computation unit. The primary AC power supply applies an AC current of a predetermined frequency to the primary driving electrode. The primary detection unit detects the voltage signal generated by the primary detection electrode. The secondary AC power supply applies an AC current to the secondary driving electrode. The secondary detection unit detects the voltage signal generated by the secondary detection electrode. The computation unit calculates the angular velocity based on the output signal of the secondary AC power supply.

[0016] -The effects of the invention-

[0017] According to the vibrating gyroscope element disclosed herein, the bias component contained in the output signal can be reduced. According to the angular velocity sensor disclosed herein, the bias component contained in the output signal of the vibrating gyroscope element can be reduced, thereby improving the detection accuracy of angular velocity. Attached Figure Description

[0018] Figure 1 This is a top view of the vibration-type gyroscope element according to the first embodiment.

[0019] Figure 2 yes Figure 1 A sectional view at line II-II.

[0020] Figure 3 yes Figure 1 An enlarged view of the portion enclosed by the dotted line.

[0021] Figure 4 This is a simplified diagram of the circuit block of the angular velocity sensor.

[0022] Figure 5A This is a diagram showing the primary vibration.

[0023] Figure 5B This is a diagram showing the secondary vibration.

[0024] Figure 6A This is a top view showing the electrode arrangement before switching between the primary and secondary sides.

[0025] Figure 6B This is a top view showing the electrode arrangement after switching between the primary and secondary sides.

[0026] Figure 7 It is a schematic diagram showing how the displacement of the secondary detection electrode changes over time during operation.

[0027] Figure 8 This is a schematic diagram illustrating the actual output signal of the secondary detection electrode and the vibration angle dependence of the various signals contained therein.

[0028] Figure 9 This is a top view showing the electrode arrangement used for comparison.

[0029] Figure 10 This is a top view showing the electrode arrangement involved in Modified Example 1.

[0030] Figure 11 This is a top view showing the electrode arrangement involved in Modified Example 2.

[0031] Figure 12 This is a top view showing the electrode arrangement involved in Modified Example 3.

[0032] Figure 13 This is a top view showing the electrode arrangement involved in Modified Example 4.

[0033] Figure 14 This is a simplified structural diagram of the angular velocity sensor according to the second embodiment.

[0034] Figure 15 This is a top view of a piezoelectric vibrating gyroscope element.

[0035] Figure 16 yes Figure 15 A cross-sectional view at line XVI-XVI. Detailed Implementation

[0036] The embodiments of this disclosure will now be described with reference to the accompanying drawings. It should be noted that the following description of preferred embodiments is merely illustrative in nature and is not intended to limit this disclosure, its application, or its uses.

[0037] (First Implementation)

[0038] [Structure of a Vibrating Gyroscope Element]

[0039] Figure 1 This is a top view showing the vibration-type gyroscope element according to the first embodiment. Figure 2 It is shown Figure 1 A sectional view at line II-II. Figure 3 It is shown Figure 1 An enlarged view of the portion enclosed by the dotted line.

[0040] It should be noted that, for ease of explanation, in Figure 1 , Figure 3 The diagram of the magnetic field application unit 60 is omitted. Additionally, it should be noted that... Figures 1-3 The diagram schematically illustrates the structure of the vibrating gyroscope element 100 and does not precisely show the actual dimensional relationships between the components.

[0041] It should be noted that in the following description, the radial direction of the oscillator 20 is sometimes referred to as the radial direction, the outer circumferential direction of the oscillator 20 as the circumferential direction, and the direction orthogonal to the radial and circumferential directions as the axial direction. Furthermore, in the radial direction, the center side of the oscillator 20 is sometimes referred to as the inner or inner side, and the outer circumferential side of the oscillator 20 as the outer or outer side. In the axial direction, the side with the upper magnetic yoke 61 (see reference...) is sometimes... Figure 2 The side of the magnetic yoke 63 (see reference) is called the upper or upper side, and the lower magnetic yoke 63 will be provided thereon. Figure 2 The side of the component shown below is called the bottom or lower side. It should be noted that sometimes the upper surface of the components shown below is called the front, and the lower surface is called the back.

[0042] Additionally, sometimes one or more primary driving electrodes are collectively referred to as primary driving electrodes (PD), and one or more primary detection electrodes are collectively referred to as primary detection electrodes (PPO). Similarly, sometimes one or more secondary driving electrodes are collectively referred to as secondary driving electrodes (SD), and one or more secondary detection electrodes are collectively referred to as secondary detection electrodes (SPO).

[0043] like Figure 1 , Figure 2 As shown, the vibration type gyroscope element 100 has a fixing part 10, an oscillator 20, multiple support parts 30, multiple electrodes 40a to 40p, and a magnetic field application part 60.

[0044] like Figure 1 As shown, the fixing part 10 has an opening 10a in the central part, and an oscillator 20, a plurality of support parts 30, a plurality of electrodes 40a to 40p, and a magnetic field application part 60 are arranged inside the opening 10a. Additionally, as... Figure 2 As shown, the fixing part 10 is a component with a stacked structure, which is formed by sequentially stacking a first silicon layer 51, a silicon oxide layer (insulating layer) 52, and a second silicon layer 53. In addition, a silicon oxide film 54 is formed on the front side of the second silicon layer 53.

[0045] The oscillator 20 is a ring-shaped component obtained by processing the second silicon layer 53, and has a cos2θ vibration mode.

[0046] The support portion 30 is a component obtained by processing the second silicon layer 53, and is integrally formed with the oscillator 20. In addition, the support portion 30 connects the oscillator 20 to the fixing portion 10 and supports the oscillator 20 in a cantilever manner. In other words, the support portion 30 supports the oscillator 20 in a way that allows the oscillator 20 to vibrate.

[0047] like Figure 3As shown, the plurality of support portions 30 each have a first foot 31 and a second foot 32. The first foot 31 and the second foot 32 each have a first end portion 30a and a second end portion 30b. The first end portion 30a is connected to different positions of the vibrator 20 with a first gap. The second end portion 30b is connected to different positions of the fixing portion 10 with a second gap narrower than the first gap.

[0048] Furthermore, the first foot portion 31 has a first portion 31a and a second portion 31c. The first portion 31a extends radially outward from the first end portion 30a toward the oscillator 20, and the second portion 31c bends at a first bend portion 31b, which is one end of the first portion 31a, and extends parallel to the outer periphery of the oscillator 20. Additionally, the first foot portion 31 has a third portion 31e, which bends at a second bend portion 31d, which is one end of the second portion 31c, extends radially outward toward the oscillator 20, and reaches the second end portion 30b.

[0049] Similarly, the second foot 32 has a first portion 32a and a second portion 32c. The first portion 32a extends radially outward from the first end 30a toward the oscillator 20, and the second portion 32c bends at a first bend 32b, which is one end of the first portion 32a, and extends parallel to the outer periphery of the oscillator 20. Additionally, the second foot 32 has a third portion 32e, which bends at a second bend 32d, which is one end of the second portion 32c, extends radially outward toward the oscillator 20, and reaches the second end 30b.

[0050] The second portion 31c of the first leg 31 and the second portion 32c of the second leg 32 extend to the second bends 31d and 32d respectively, close to each other. Furthermore, the third portion 31e of the first leg 31 and the third portion 32e of the second leg 32 are spaced apart by a predetermined interval and extend side-by-side from the second bends 31d and 32d to the second end 30b respectively. Additionally, the first leg 31 and the second leg 32 are arranged symmetrically about an imaginary line passing through the center of the oscillator 20 and between the respective third portions 31e and 32e of the first leg 31 and the second leg 32.

[0051] Electrodes 40a to 40p are annular conductive components formed within the surface of the oscillator 20. Furthermore, electrodes 40a to 40p extend from the front surfaces of the support portion 30 and the fixing portion 10, respectively. For example, as... Figure 3As shown, electrode 40d starts from the second end 30b of the first foot 31, passes through the oscillator 20 between the first foot 31 and the first end 30a, and extends to the second end 30b of the second foot 32. Electrode 40d is formed on the front side of the silicon oxide film 54. It should be noted that in the following description, without particular attention to the arrangement and function of the electrodes, electrodes 40a to 40p are sometimes collectively referred to as electrode 40. It should be noted that some or all of the functionally identical electrodes 40 arranged in different orientations are connected by wiring (not shown) provided in the fixing part 10. It should be noted that the term "orientation" in this specification corresponds to the "area" where electrodes 40 are arranged; when these areas are adjacent, they are continuous. Electrode 40 may also span an entire orientation. Furthermore, the size of electrode 40 may be smaller than the size of an orientation (area). Multiple electrodes 40 may also be arranged in the same orientation.

[0052] In addition, such as Figure 1 , Figure 3 As shown, the two electrodes 40 are formed to extend side by side with a gap between them within the surfaces of the support portion 30 and the oscillator 20. Furthermore, within the surfaces of the support portion 30 and the oscillator 20, the two electrodes 40e and 40m are formed to extend side by side with a gap between them. It should be noted that, in this specification, "side by side" includes not only the case where the two components are arranged parallel to each other, but also the case where the two components are arranged with a gap between them to a degree that they do not contact or intersect each other.

[0053] exist Figure 3 In this configuration, among the two electrodes 40d and 40l arranged in a ring on the front side of one support portion 30, the outer electrode 40d is the primary driving electrode PD, and the inner electrode 40l is the primary detection electrode PPO. Similarly, among the two electrodes 40e and 40m arranged in a ring on the front side of the other support portion 30, the outer electrode 40e is the secondary driving electrode SD, and the inner electrode 40m is the secondary detection electrode SPO. In other words, the primary detection electrode PPO is positioned in the same orientation as the primary driving electrode PD, and the secondary driving electrode SD is positioned in the same orientation as the secondary detection electrode SPO.

[0054] like Figure 1 As shown, the combination of the primary driving electrode PD and the primary detection electrode PPO, and the combination of the secondary driving electrode SD and the secondary detection electrode SPO are arranged alternately throughout the circumference. Furthermore, the same number of the combinations of the primary driving electrode PD and the primary detection electrode PPO, and the combinations of the secondary driving electrode SD and the secondary detection electrode SPO, are provided.

[0055] A combination of primary driving electrodes (PD) and primary detection electrodes (PPO), along with the nearest combination of primary driving electrodes (PD) and primary detection electrodes (PPO) to this combination, are arranged at a 90-degree angle to each other. A combination of secondary driving electrodes (SD) and secondary detection electrodes (SPO), along with the nearest combination of secondary driving electrodes (SD) and secondary detection electrodes (SPO) to this combination, are arranged at a 90-degree angle to each other. A combination of primary driving electrodes (PD) and primary detection electrodes (PPO), along with the nearest combination of secondary driving electrodes (SD) and secondary detection electrodes (SPO) to this combination, are arranged at a 45-degree angle to each other.

[0056] It should be noted that each of the multiple electrodes 40a to 40p has electrode pads (not shown) at both ends. The four primary detection electrodes PPO are connected in series via the electrode pads. Similarly, the four secondary detection electrodes SPO are connected in series via the electrode pads.

[0057] like Figure 2 As shown, the magnetic field applying part 60 has an upper yoke 61, a magnet 62, and a lower yoke 63. The upper yoke 61 and the lower yoke 63 are both bottomed cylindrical components formed of a magnetic material such as iron. The upper yoke 61 and the lower yoke 63 are arranged such that the cylindrical portions of the upper yoke 61 and the lower yoke 63 are axially spaced apart. Furthermore, an oscillator 20 is arranged between the cylindrical portions of the upper yoke 61 and the lower yoke 63. The oscillator 20 is arranged between the cylindrical portions of the upper yoke 61 and the lower yoke 63, respectively, with axial gaps between them.

[0058] One of the upper and lower parts of the magnet 62 is the N pole, and the other is the S pole. The magnet 62 is held by the upper yoke 61 or the lower yoke 63, or both, and is fixedly arranged inside the oscillator 20.

[0059] Magnetic flux flowing from one pole of magnet 62 passes through one of the upper yoke 61 and the lower yoke 63, and reaches oscillator 20 and electrodes 40a-40p formed on the front side of oscillator 20. Further, the magnetic flux passes through oscillator 20 and electrodes 40a-40p, and flows into the other pole of magnet 62 via the other of the upper yoke 61 and the lower yoke 63.

[0060] In this way, the magnetic field applying part 60 applies a magnetic field to the plurality of electrodes 40a to 40p along the direction intersecting the front of the oscillator 20, which in this case is along the axial direction. It should be noted that the magnetic field applying part 60 is supported by a support substrate (not shown), thereby maintaining its position relative to the oscillator 20 in the radial and axial directions.

[0061] The vibration-type gyroscope element 100, other than the magnetic field application part 60, is a MEMS (Micro Electro Mechanical Systems) element obtained by processing a known SOI (Silicon On Insulator) substrate using microfabrication technology that applies semiconductor microfabrication technology.

[0062] The MEMS device is manufactured, for example, by thermal oxidation of an SOI substrate having a first silicon layer 51, a silicon oxide layer 52, and a second silicon layer 53, forming a silicon oxide film 54 on the front side of the second silicon layer 53.

[0063] Next, a plurality of electrodes 40a to 40p are formed on the front side of the silicon oxide film 54 using a mask pattern (not shown). For example, a metal film is attached to the front side of the silicon oxide film 54 using a mask pattern, thereby forming a plurality of electrodes 40a to 40p.

[0064] Using a different mask pattern (not shown), the silicon oxide film 54 and the second silicon layer 53 are etched and removed until the silicon oxide layer 52 is reached. After this process, a prototype of the support portion 30 and the oscillator 20 is formed.

[0065] Next, with the electrodes 40a-40p, the support portion 30, and the front surface of the oscillator 20 protected by wax or the like, the first silicon layer 51 located below the support portion 30 and the oscillator 20 is etched and removed using a mask pattern (not shown) corresponding to the opening 10a of the fixing portion 10. Further, using the same mask pattern, the silicon oxide layer 52 is etched and removed to obtain the aforementioned MEMS device.

[0066] It should be noted that the etching of the first silicon layer 51 and the silicon oxide layer 52 can be performed using either dry etching or wet etching. However, when using either etching method, it is preferable to use an etchant that has high etching selectivity for the substrate layer to be etched.

[0067] [Structure and operation of the angular velocity sensor]

[0068] Figure 4 A simplified diagram of the circuit block for an angular velocity sensor is shown. It should be noted that, for ease of explanation, [the diagram is simplified here]. Figure 4 The diagram only briefly shows the primary drive electrode PD, primary detection electrode PPO, secondary drive electrode SD, and secondary detection electrode SPO in the vibrating gyroscope element 100.

[0069] like Figure 4As shown, the angular velocity sensor 1000 includes: a vibration type gyroscope element 100, a primary AC power supply 200, a primary detection unit 210, a secondary AC power supply 220, a secondary detection unit 230, an arithmetic unit 240, a switching unit 250, and multiple switches 260.

[0070] Four primary drive electrodes PD are connected to the primary AC power supply 200. Four primary detection electrodes PPO connected in series are connected to the primary detection unit 210. Four secondary drive electrodes SD are connected to the secondary AC power supply 220. Four secondary detection electrodes SPO connected in series are connected to the secondary detection unit 230. Additionally, the secondary AC power supply 220 is connected to the arithmetic unit 240.

[0071] The following describes the operation of the angular velocity sensor 1000.

[0072] When an alternating current Ip is supplied from the primary AC power supply 200 to the primary drive electrode PD, a Lorentz force is applied to the primary drive electrode PD. The direction of this Lorentz force intersects the direction of the magnetic field applied from the magnetic field application unit 60 and the direction in which the alternating current Ip flows. In other words, the Lorentz force acts in a direction parallel to the front surface of the oscillator 20. The oscillator 20, on which the primary drive electrode PD is located, deforms under this Lorentz force. Furthermore, since the direction of the Lorentz force periodically reverses according to the frequency of the alternating current Ip, the oscillator 20 vibrates at the same frequency. In this case, the oscillator 20 vibrates in a direction parallel to its front surface.

[0073] By setting the frequency of the alternating current Ip to match the resonant frequency of the oscillator 20, the primary vibration of the cos2θ mode is excited on the oscillator 20.

[0074] Furthermore, to generate such primary oscillation in the oscillator 20, the alternating current Ip needs to flow to the four primary drive electrodes PD respectively. Specifically, it is set such that the direction of the alternating current Ip between two primary drive electrodes PD positioned 90 degrees apart is opposite to each other; that is, when viewed from above, the directions are clockwise and counterclockwise. Additionally, the connection relationship between the four primary drive electrodes PD and the primary AC power supply 200 only needs to satisfy the above settings; the four primary drive electrodes PD can be connected in series or in parallel with respect to the primary AC power supply 200.

[0075] The primary detection electrode PPO detects the primary vibration and generates a voltage signal whose magnitude corresponds to its amplitude. This voltage signal is fed back to the primary detection unit 210. Based on the voltage signal generated by the primary detection electrode PPO, the primary detection unit 210 outputs an output signal to the primary AC power supply 200. Based on the output signal from the primary detection unit 210, the amplitude and frequency of the primary AC power supply 200 are controlled; specifically, the amplitude and frequency of the AC current Ip are controlled to keep the vibration frequency and amplitude of the oscillator 20 constant.

[0076] Figure 5A The primary vibration state of the oscillator is schematically shown. Figure 5B The secondary vibration state of the oscillator is schematically shown.

[0077] like Figure 5A As shown, the annular oscillator 20 periodically undergoes primary vibration in an elliptical shape with mutually orthogonal principal axes. However, when a Coriolis force is applied to the oscillator 20, causing an angular velocity about the axial direction, the direction of the principal axes of the aforementioned ellipse changes. Figure 1 In the case of the vibration-type gyroscope element 100 of this embodiment shown, as Figure 5B As shown, compared with the case of primary vibration, the principal axis of the ellipse changes to a position rotated by 45 degrees, and the oscillator 20 becomes a secondary vibration state.

[0078] A magnetic field is also applied to the secondary detection electrode SPO in a direction intersecting its front surface. Furthermore, corresponding to the vibration of the oscillator 20, the secondary detection electrode SPO also vibrates in a direction parallel to its front surface. As a result, a sinusoidal alternating voltage is generated on the secondary detection electrode SPO, corresponding to the strength of the magnetic field and the speed of its vibration. Moreover, since the speed of the secondary detection electrode SPO differs between the primary vibration state and the secondary vibration state of the oscillator 20, the voltage generated in each state is also different.

[0079] The secondary detection unit 230 detects the voltage generated by the secondary detection electrode SPO and outputs a signal corresponding to the magnitude of the voltage to the secondary AC power supply 220.

[0080] 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 current to the secondary drive electrode SD to drive the oscillator 20, thereby canceling the secondary vibration generated by the oscillator 20. Additionally, the secondary AC power supply 220 inputs an output signal based on the output current to the arithmetic unit 240.

[0081] The arithmetic unit 240 determines whether the oscillator 20 is in a primary vibration state or a secondary vibration state based on the output signal of the secondary AC power supply 220. Furthermore, if it is determined that the oscillator 20 is in a secondary vibration state, the arithmetic unit 240 calculates the angular velocity based on the output signal of the secondary AC power supply 220.

[0082] Furthermore, the angular velocity sensor 1000 switches between the primary and secondary sides at a predetermined time, acquires the output signal from the vibrating gyroscope element 100, and calculates the angular velocity based on this output signal. For example, the angular velocity is calculated based on the difference between the output signals before and after the switch. This switching action utilizes... Figure 4 The switch 260 and switching unit 250 shown are used to switch the internal wiring. It should be noted that the "prescribed time" can be selected when the vibrating gyroscope element 100 is in a stationary state or in a constant speed motion state, etc.

[0083] Figure 6A This shows the electrode arrangement before switching between the primary and secondary sides. Figure 6B The electrode arrangement is shown after switching between the primary and secondary sides.

[0084] Figure 6A The electrode arrangement shown is Figure 1 The electrodes shown are arranged identically. Therefore, electrodes 40b, 40d, 40f, and 40h function as primary driving electrodes (PD), and electrodes 40j, 40l, 40n, and 40p function as primary detection electrodes (PPO). Additionally, electrodes 40a, 40c, 40e, and 40g function as secondary driving electrodes (SD), and electrodes 40i, 40k, 40m, and 40o function as secondary detection electrodes (SPO).

[0085] The internal wiring of the angular velocity sensor 1000 is switched by sending control signals from the switching unit 250 to four switches 260 at predetermined times. As a result, electrodes 40b, 40d, 40f, and 40h are connected to the secondary AC power supply 220, and... Figure 6B As shown, electrodes 40j, 40l, 40n, and 40p are connected to the secondary detection unit 230 and function as the secondary detection electrodes SPO. Electrodes 40a, 40c, 40e, and 40g are connected to the primary AC power supply 200 and function as the primary drive electrodes PD. Electrodes 40i, 40k, 40m, and 40o are connected to the primary detection unit 210 and function as the primary detection electrodes PPO.

[0086] It should be noted that the vibrating gyroscope element 100, primary AC power supply 200, primary detection unit 210, secondary AC power supply 220, secondary detection unit 230, and arithmetic unit 240 can be mounted on different substrates or on the same substrate. The vibrating gyroscope element 100, primary AC power supply 200, primary detection unit 210, secondary AC power supply 220, secondary detection unit 230, and arithmetic unit 240 can also be housed in different packages (not shown). Furthermore, the vibrating gyroscope element 100 and other components can be mounted on different substrates or housed in different packages. In this case, the primary AC power supply 200 and secondary AC power supply 220 can also be further mounted on different substrates or housed in different packages.

[0087] [Regarding the second harmonic component contained in the output signal of the secondary detection electrode]

[0088] Figure 7 The diagram schematically illustrates the change in displacement of the secondary detection electrode over time during operation. Figure 8 The actual output signal of the secondary detection electrode and the vibration angle dependence of the various signals contained therein are schematically shown.

[0089] It should be noted that, Figure 7 The secondary detection electrode SpO shown in Figure (a) is... Figure 7 The secondary detection electrodes SpO shown in Figure (b) are positioned 90 degrees apart circumferentially. That is, the two secondary detection electrodes SpO are orthogonal to each other. Furthermore, Figure 7 The hollow arrows shown in Figures (a) and (b) indicate the direction of the electromotive force of the voltage generated by the secondary detection electrode SPO.

[0090] It should be noted that, Figure 8 The vibration angle shown corresponds to the product of the frequency and time of the AC voltage generated by the secondary detection electrode SPO. Additionally, in Figure 8 The actual output signals associated with SPO(L) and SPO(R), which will be described later, and the various signals contained therein are shown.

[0091] As described above, when the alternating current Ip flows, a Lorentz force acts on the primary drive electrode PD due to the magnetic field and the alternating current Ip. This Lorentz force is also applied to the oscillator 20, causing the oscillator 20 to deform and vibrate periodically.

[0092] In addition, in order to excite the primary vibration of the cos2θ mode on the oscillator 20, the direction of the alternating current Ip flowing to the four primary driving electrodes PD is alternately reversed. That is, the primary driving electrodes PD with the alternating current Ip flowing in the clockwise direction and the primary driving electrodes PD with the alternating current Ip flowing in the counterclockwise direction are arranged alternately.

[0093] Therefore, at both ends of the portion of the secondary detection electrode SPO that is clamped by the primary drive electrode PD and formed within the plane of the oscillator 20, forces acting in opposite directions are applied radially. Furthermore, the direction of the forces changes periodically.

[0094] In addition, the secondary detection electrode SPO, which is adjacent to the combination of the primary driving electrode PD and the primary detection electrode PPO, is located at a circumferential distance of 45 degrees from electrodes PD and PPO.

[0095] Therefore, as Figure 7 As shown in Figures (a) and (b), the portion of the secondary detection electrode SPO formed within the plane of the oscillator 20 deforms symmetrically within a plane parallel to the front surface of the oscillator 20, with an imaginary central axis extending radially from its circumferential central portion. That is, when one end displaces radially inward from its pre-operational position, the other end displaces radially outward; conversely, when one end displaces radially outward from its pre-operational position, the other end displaces radially inward. Furthermore, this deformation is repeated at a predetermined period, which is self-evident.

[0096] It should be noted that, in the following description, the portion of the secondary detection electrode SPO located on the left side of the paper relative to the central axis is sometimes referred to as SPO(L), and the portion of the secondary detection electrode SPO located on the right side of the paper relative to the central axis is referred to as SPO(R).

[0097] in addition, Figure 7 The secondary detection electrode SpO shown in Figure (a) is... Figure 7As shown in Figure (b), the secondary detection electrode SPO shifts symmetrically over time. Specifically, in the example shown in Figure (a), as time progresses from time t0 before operation to time t1, SPO(L) shifts radially outward, and SPO(R) shifts radially inward. Conversely, in the example shown in Figure (b), SPO(L) shifts radially inward, and SPO(R) shifts radially outward. At time t2, as shown in Figures (a) and (b), SPO returns to the same position as at time t0. When time progresses to time t3, in the example shown in Figure (a), SPO(L) shifts radially inward, and SPO(R) shifts radially outward. Conversely, in the example shown in Figure (b), SPO(L) shifts radially outward, and SPO(R) shifts radially inward. When time further progresses to time t4, as shown in Figures (a) and (b), SPO returns to the same position as at time t0.

[0098] Figure 7 In Figures (a) and (b), the secondary detection electrode SPO and the oscillator 20 directly below it periodically repeat the deformation described above. Furthermore, on the oscillator 20 directly below the secondary detection electrode SPO, the moving speed is at its maximum or minimum at the position where the deformation is zero, therefore the amplitude of the voltage generated by the secondary detection electrode SPO is also at its maximum or minimum. Similarly, at the position where the deformation is maximum or minimum, the moving speed is zero, therefore the amplitude of the voltage generated by the secondary detection electrode SPO is also zero.

[0099] Furthermore, as mentioned above, when the secondary detection electrode SPO deforms, there is a slight difference in the amount of deformation on the radially outer and radially inner sides. Correspondingly, as... Figure 8 As shown, the voltage generated by the secondary detection electrode SpO contains a distortion component superimposed on the fundamental sine wave (hereinafter sometimes referred to as the fundamental signal). This distortion component corresponds to the difference between the actual output signal of the secondary detection electrode SpO and the fundamental signal (hereinafter referred to as the differential signal).

[0100] Figure 8 The actual output signal of the secondary detection electrode SPO is shown, along with the fundamental and differential signals contained therein. Additionally, Figure 8 The t0~t4 shown are Figure 7 The times t0 to t4 described in the text correspond to those times.

[0101] Considering a secondary detection electrode SPO, we can assume that the fundamental frequencies in SPO(L) and SPO(R) are opposite, meaning that when one is positive, the other is negative. In the ideal output signal case where the differential signal is zero, the signal of the combined SPO (L) and SPO(R) is zero. However, due to the superposition of the aforementioned distortion components, the differential signal is in the same direction relative to the fundamental frequency in both SPO(L) and SPO(R), but its sign changes at twice the frequency relative to the fundamental. Considering this, we can say that a signal with a frequency twice that of the fundamental signal, or in other words, twice the frequency of the alternating current Ip, is generated in a secondary detection electrode SPO. This signal will be referred to as the second harmonic component.

[0102] Since the second harmonic component is an error component relative to the output signal of the secondary detection electrode SpO, it can become a bias component in the detected angular velocity value. This poses a problem when high-precision angular velocity determination is required.

[0103] In addition, such as Figure 8 As shown, since this second harmonic component is formed by the superposition of in-phase differential signals generated by SpO(L) and SpO(R), the amplitude of this second harmonic component is approximately twice that of the original signal. Therefore, its impact on the detected angular velocity value is also greater.

[0104] On the other hand, such as Figure 7 As shown, the two secondary detection electrodes SpO, positioned 90 degrees apart circumferentially, shift symmetrically over time. Therefore, the second harmonic components in the output signals of each secondary detection electrode SpO are out of phase. Consequently, if the output signals of the two secondary detection electrodes SpO are added together, the second harmonic components will cancel each other out, becoming almost zero.

[0105] In the vibration-type gyroscope element 100 shown in this embodiment, such as Figure 1 As shown, the four secondary detection electrodes SPO are arranged at 90-degree intervals from each other in the circumferential direction. Furthermore, since the voltages generated by the four secondary detection electrodes SPO are summed to form the output signal, the output signal of the secondary detection electrodes SPO that is ultimately input to the secondary detection unit 230 contains almost no second harmonic component, thus reducing error components.

[0106] [Effects, etc.]

[0107] In summary, the vibration-type gyroscope element 100 involved in this embodiment includes at least: a fixed part 10, an oscillator 20, a support part 30, and electrodes 40a to 40p. The support part 30 connects the oscillator 20 to the fixed part 10 and supports the oscillator 20 in a manner that allows the oscillator 20 to vibrate. The electrodes 40a to 40p are respectively formed in a ring shape within the surface of the oscillator 20.

[0108] When the oscillator 20 has a cos2θ vibration mode, the electrodes 40a to 40p are arranged in eight directions. These eight directions are arranged at equal angular intervals in the outer circumferential direction of the oscillator 20, and in this case, at 45-degree intervals.

[0109] Among the 16 electrodes 40a-40p, there are a primary driving electrode PD and a primary detection electrode PPO. The primary driving electrode PD excites primary vibrations in the cos2θ mode on the oscillator 20, and the primary detection electrode PPO detects the primary vibrations. Additionally, among the 16 electrodes 40a-40p, there are a secondary detection electrode SPO and a secondary driving electrode SD. The secondary detection electrode SPO detects the secondary vibrations generated when the oscillator 20 is given an angular velocity, and the secondary driving electrode SD drives the oscillator 20 to counteract the secondary vibrations.

[0110] The primary detection electrode PPO and the primary driving electrode PD are arranged in the same orientation, and the secondary driving electrode SD and the secondary detection electrode SPO are arranged in the same orientation. In addition, combinations of primary driving electrode PD and primary detection electrode PPO, and combinations of secondary driving electrode SD and secondary detection electrode SPO are alternately arranged in eight orientations.

[0111] In addition, the vibrating gyroscope element 100 also includes a magnetic field application section 60, which applies a magnetic field to 16 electrodes 40a to 40p along a direction that intersects the front of the oscillator 20, which in this case is along the axial direction.

[0112] By configuring the vibration-type gyroscope element 100 in this way, when the angular velocity sensor 1000 performs a switching operation between the primary and secondary sides, the bias component included in the output signal of the vibration-type gyroscope element 100 can be reduced. This will be further explained with reference to the accompanying drawings.

[0113] Figure 9 The arrangement of electrodes 40 used for comparison is shown. Figure 9 The vibration-type gyroscope element 110 shown has, for example, the same structure as the vibration-type gyroscope element disclosed in Patent Document 1.

[0114] exist Figure 9In the vibrating gyroscope element 110 shown, electrodes 40a to 40h are arranged on eight support portions 30. Furthermore, the primary drive electrode PD, secondary drive electrode SD, primary detection electrode PPO, and secondary detection electrode SPO are arranged sequentially in eight positions along the circumferential direction in a clockwise direction. Additionally, two of each type of electrode PD, SD, PPO, and SPO are arranged, with electrodes of the same type positioned 180 degrees apart circumferentially.

[0115] However, in the vibrating gyroscope elements 100 and 110, during operation, forces act on each electrode 40a to 40p, and corresponding mechanical motion axes can be imagined. For example, if the axis associated with the primary drive electrode PD is designated as the PD axis, then according to the arrangement of the electrodes, the motion axes associated with the secondary drive electrode SD, the primary detection electrode PPO, and the secondary detection electrode SPO, namely the SD axis, the PPO axis, and the SPO axis, respectively, uniquely determine a prescribed angular relationship between them and the PD axis.

[0116] On the other hand, the oscillator 20 also has imaginary axes of motion for the primary and secondary vibrations. Ideally, the axis of motion for the primary vibration coincides with the PD axis. In this case, the axis of motion for the secondary vibration also coincides with the SD axis.

[0117] However, as described above, angular deviations between electrodes 40a and 40p and uneven applied magnetic fields typically occur in the vibrating gyroscope element 110. These conditions cause angular deviations between the motion axis of the primary vibration and the PD axis. Furthermore, the angular deviations between electrodes 40a and 40p also cause deviations in the angular relationship between the PD axis and the SD axis. Similarly, deviations also occur in the angular relationships between the PPO axis and the SPO axis and the PD axis. The aforementioned bias components arise due to these angular deviations.

[0118] The inventors of this application have discovered that the noise component generated by the angular deviation between the PD axis and the motion axes of electrodes SD, PPO, and SPO other than the PD axis is superimposed on the bias component. Even if the angular velocity sensor 1000 is operated by switching between the primary side and the secondary side as disclosed in Patent Document 3 to remove the difference in the output signal, the noise component will not be eliminated.

[0119] Therefore, the inventors of this application discovered that by focusing on the arrangement relationship of each electrode PD, SD, PPO, and SPO, in Figure 1 By arranging the electrodes PD, SD, PPO, and SPO at the positions shown, the angular deviation between the PD axis and the other motion axes (SD, PPO, and SPO) can be reduced. In this way, by using the switching action between the primary and secondary sides to remove the differential of the output signal, the bias component can be essentially eliminated.

[0120] Furthermore, the two electrodes 40 are formed to extend side-by-side from the support portion 30 to the oscillator 20 with a gap between them. One electrode 40 disposed on one support portion 30 is the primary drive electrode PD, and the other electrode 40 is the primary detection electrode PPO. One electrode 40 disposed on the other support portion 30 is the secondary drive electrode SD, and the other electrode 40 is the secondary detection electrode SPO.

[0121] By arranging electrodes 40a to 40p on the eight support portions 30 as described above, the primary detection electrode PPO and the primary drive electrode PD can be easily arranged in the same orientation. Furthermore, the secondary drive electrode SD and the secondary detection electrode SPO can be easily arranged in the same orientation. This reduces the angular deviation between the PD axis and the motion axes other than the PD axis, namely the SD axis, PPO axis, and SPO axis, thereby significantly reducing the bias component included in the output signal of the vibrating gyroscope element 100. Additionally, it suppresses unnecessary large-scale development of the vibrating gyroscope element 100.

[0122] Furthermore, given this, it can be said that each of the electrodes 40a to 40p is hypothetically assumed to have a mechanical axis of motion. Therefore, it can also be said that the arrangement orientation of the electrodes 40a to 40p is the orientation in which their respective hypothetical axes of motion (hereinafter sometimes referred to as the axes of the electrodes 40) are arranged at equal angular intervals in the outer circumferential direction of the oscillator 20.

[0123] The four secondary detection electrodes SPO are preferably connected in series with each other.

[0124] This allows for a larger voltage signal to be obtained for detecting secondary vibrations. Consequently, the signal-to-noise ratio (S / N ratio) of the output signal of the secondary detection unit 230 can be increased, thereby improving the detection accuracy of the angular velocity calculated by the calculation unit 240.

[0125] Furthermore, for the same reason, the four primary detection electrodes PPO are preferably connected in series.

[0126] The four secondary detection electrodes SPO are preferably arranged at 90-degree intervals from each other in the circumferential direction. This reduces the error component, i.e., the second harmonic component, in the output signal of the secondary detection electrodes SPO.

[0127] Furthermore, preferably, the support portion 30 on which the electrode 40 is arranged is composed of a first foot 31 and a second foot 32, wherein the first foot 31 has the aforementioned first to third portions 31a, 31c, and 31e, and the second foot 32 has the first to third portions 32a, 32c, and 32e. More preferably, the first foot 31 and the second foot 32 are arranged symmetrically about an imaginary line, which passes through the center of the oscillator 20 and between the third portions 31e and 32e of the first foot 31 and the second foot 32, respectively.

[0128] By configuring the support portion 30 in this way, the oscillator 20 can be supported in a manner that does not significantly affect its vibration during primary vibration. Furthermore, the support portion 30 is arranged at equal angular intervals in the circumferential direction, and the first foot 31 and the second foot 32 are symmetrically arranged about the aforementioned imaginary line, thereby enabling the oscillator 20 to be stably connected to the fixing portion 10. Thus, the oscillator 20 can stably perform primary vibration.

[0129] Furthermore, the vibration-type gyroscope element 100 according to this embodiment can reduce the crosstalk voltage included in the voltage generated by the secondary detection electrode SPO. This will be explained further.

[0130] When the primary drive electrode PD and the secondary detection electrode SPO are close to each other, mutual inductance is generated on the secondary detection electrode SPO due to the alternating current flowing in the primary drive electrode PD, thereby inducing a crosstalk voltage. This crosstalk voltage is also superimposed on the vibrating gyroscope element 100 as an error component.

[0131] On the other hand, in the vibration-type gyroscope element 100 of this embodiment, such as Figure 1 As shown, a combination of a primary driving electrode PD and a primary detection electrode PPO is arranged on both sides of the combination of the secondary driving electrode SD and the secondary detection electrode SPO.

[0132] As described above, in order to excite the primary vibration of the cos2θ mode in the oscillator 20, the primary driving electrode PD through which the alternating current Ip flows in the clockwise direction and the primary driving electrode PD through which the alternating current Ip flows in the counterclockwise direction are arranged alternately.

[0133] In this case, crosstalk voltages of the same magnitude but with different directions of electromotive force are induced on the secondary detection electrode SPO arranged between the two primary driving electrodes PD. As a result, the crosstalk voltages cancel each other out and become almost zero. This reduces the crosstalk voltage, thereby improving the detection accuracy of angular velocity.

[0134] In addition, such as Figure 3As shown, at the portion closest to the primary driving electrode PD and the secondary detection electrode SPO, specifically at the first portions 31a and 32a of the support portion 30, a secondary driving electrode SD is arranged between the primary driving electrode PD and the secondary detection electrode SPO. Therefore, the mutual inductance between the primary driving electrode PD and the secondary detection electrode SPO is reduced, thereby reducing the magnitude of the crosstalk voltage.

[0135] It should be noted that in the structures shown in variations 2 to 4 described later, the same as... Figure 9 Compared to the structure shown, it can also reduce the crosstalk voltage contained in the voltage generated by the secondary detection electrode SPO, thereby improving the detection accuracy of angular velocity.

[0136] It should be noted that, depending on the arrangement and number of the primary drive electrodes PD, the oscillator 20 can adopt a vibration mode of cosNθ (where N is a natural number greater than 2). In this case, the arrangement of the axes of the electrodes 40 is 4N.

[0137] In other words, in the vibration type gyroscope element 100 of this embodiment, when the oscillator 20 has a vibration mode of cosNθ, the support 30 and the electrode 40 are respectively arranged in 4N directions, and the axes of the electrode 40 are arranged at equal angular intervals in the outer peripheral direction of the oscillator 20 in the 4N directions.

[0138] Additionally, a support portion 30 is arranged at a distance of (360 / 4N) degrees from the other support portions 30. That is, the combination of the primary driving electrode PD and the primary detection electrode PPO, and the combination of the adjacent secondary driving electrode SD and the secondary detection electrode SPO, are arranged at a distance of (360 / 4N) degrees from each other.

[0139] Furthermore, the plurality of secondary detection electrodes SPO included in the vibrating gyroscope element 100 are preferably arranged at positions circumferentially separated by (360 / 2N + 360 × (M / N)) degrees. Here, M is an integer and satisfies the relationship 0 ≤ M ≤ N - 1. In this way, the error component, i.e., the second harmonic component, contained in the output signal of the secondary detection electrodes SPO can be reduced.

[0140] The angular velocity sensor 1000 of this embodiment includes at least a vibrating gyroscope element 100, 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 used to direct an AC current of a predetermined frequency to the primary drive electrode PD. The primary detection unit 210 detects the voltage signal generated by the primary detection electrode PD. The secondary AC power supply 220 is used to direct an AC current to the secondary drive electrode SD. The secondary detection unit 230 detects the voltage signal generated by the secondary detection electrode SD. The calculation unit 240 calculates the angular velocity based on the output signal of the secondary AC power supply 220.

[0141] Additionally, the angular velocity sensor 1000 includes a switching unit 250, which operates by switching between a combination of a primary drive electrode PD and a primary detection electrode PPO and a combination of a secondary drive electrode SD and a secondary detection electrode SPO at predetermined times. The calculation unit 240 calculates the angular velocity based on the output signal of the secondary AC power supply 220 before and after the switching operation.

[0142] According to the angular velocity sensor 1000 of this embodiment, the bias component contained in the output signal of the vibrating gyroscope element 100 can be reduced, thereby improving the detection accuracy of angular velocity.

[0143] Furthermore, according to this embodiment, by using the primary detection unit 210 to detect the voltage generated by the primary detection electrode PPO and feeding back the output signal of the primary detection unit 210 to the primary AC power supply 200, the primary vibration generated by the oscillator 20 can be stabilized.

[0144] Furthermore, the voltage generated by the secondary detection electrode SPO is detected by the secondary detection unit 230, and the output of the secondary AC power supply 220 is controlled based on the output signal of the secondary detection unit 230, thereby canceling the secondary vibration generated by the oscillator 20. This stabilizes the vibration state of the oscillator 20. Consequently, the noise component contained in the output signal of the secondary AC power supply 220 is reduced, improving the accuracy of angular velocity detection.

[0145] It should be noted that, in the above description, when the angular velocity sensor 1000 is operating, it operates after switching between the primary drive electrode PD and the secondary drive electrode SD at a predetermined time, and also after switching between the primary detection electrode PPO and the secondary detection electrode SPO. However, the combination of the switched electrodes 40 is not limited to this. When the angular velocity sensor 1000 is operating, it is also possible to switch between the primary drive electrode PD and the secondary detection electrode SPO at a predetermined time, and also after switching between the primary detection electrode PPO and the secondary drive electrode SD.

[0146] <Variation Example 1>

[0147] Figure 10 This is a top view showing the electrode arrangement involved in this modified example. It should be noted that... Figure 10 In the accompanying drawings shown thereafter, the same symbols are used for the same parts as in the first embodiment, and detailed descriptions are omitted.

[0148] exist Figure 10 In the structure shown, there are three sets of combinations of primary driving electrode PD and primary detection electrode PPO, and three sets of combinations of secondary driving electrode SD and secondary detection electrode SPO, which is different from the structure shown in the first embodiment.

[0149] exist Figure 10 In the structure shown, the combination of the primary driving electrode PD and the primary detection electrode PPO, and the combination of the secondary driving electrode SD and the secondary detection electrode SPO are arranged continuously and alternately in the circumferential direction.

[0150] It should be noted that the type of electrode 40 is not explicitly shown for electrodes 40a, 40h, 40i, and 40p. For example, it is not explicitly stated whether it is the primary drive electrode PD or the secondary detection electrode SPO. As mentioned above, electrodes 40 whose type is not explicitly shown are so-called dummy electrodes, set up to ensure the mass balance of the oscillator 20, and do not help in detecting the primary and secondary vibrations of the oscillator 20. In the following figures, electrodes 40 whose type is not explicitly shown are also dummy electrodes.

[0151] The vibration-type gyroscope element 100 shown in this modification can have the same effect as the structure shown in the first embodiment. That is, when the switching operation between the primary side and the secondary side is performed using the angular velocity sensor 1000, the bias component included in the output signal of the vibration-type gyroscope element 100 can be reduced.

[0152] Furthermore, the angular velocity sensor 1000, which is equipped with the vibration-type gyroscope element 100 of this modified example, has the same structure as that shown in the first embodiment, and can improve the detection accuracy of angular velocity.

[0153] <Variation Example 2>

[0154] Figure 11 This is a top view showing the electrode arrangement involved in this modified example. Two sets of combinations of primary driving electrode PD and primary detection electrode PPO, and two sets of combinations of secondary driving electrode SD and secondary detection electrode SPO are respectively provided, which is different from the structure shown in the first embodiment.

[0155] exist Figure 11In the illustrated structure, a combination of a primary driving electrode PD and a primary detection electrode PPO, and a combination of a secondary driving electrode SD and a secondary detection electrode SPO, are arranged at a circumferential distance of (360 / 4N) degrees from each other; in this case, they are arranged at a circumferential distance of 45 degrees. Alternatively, two sets of primary driving electrodes PD and primary detection electrodes PPO are arranged at a circumferential distance of (360 / N) degrees from each other; in this case, they are arranged at a circumferential distance of 180 degrees. Similarly, two sets of secondary driving electrodes SD and secondary detection electrodes SPO are arranged at a circumferential distance of 180 degrees.

[0156] The vibration-type gyroscope element 100 shown in this modified example has the same effect as the structure shown in the first embodiment. That is, when the switching operation between the primary side and the secondary side is performed using the angular velocity sensor 1000, the bias component included in the output signal of the vibration-type gyroscope element 100 can be reduced.

[0157] Furthermore, the angular velocity sensor 1000, which is equipped with the vibration-type gyroscope element 100 of this modified example, has the same structure as that shown in the first embodiment, and can improve the detection accuracy of angular velocity.

[0158] <Variation Example 3>

[0159] Figure 12 This is a top view showing the electrode arrangement involved in this modified example. Two sets of combinations of primary driving electrode PD and primary detection electrode PPO, and two sets of combinations of secondary driving electrode SD and secondary detection electrode SPO are respectively provided, which is different from the structure shown in the first embodiment.

[0160] exist Figure 12 In the structure shown, a combination of a primary driving electrode PD and a primary detection electrode PPO, and a combination of a secondary driving electrode SD and a secondary detection electrode SPO, are arranged at a circumferential distance of (360 / 4N) degrees from each other; in this case, they are arranged at a circumferential distance of 45 degrees. Alternatively, two sets of primary driving electrodes PD and primary detection electrodes PPO are arranged at a circumferential distance of (360 / 2N + 360 × (M / N)) degrees from each other. In this case, M = 0 and N = 2, and the two sets of primary driving electrodes PD and primary detection electrodes PPO are arranged at a circumferential distance of 90 degrees from each other. Similarly, two sets of secondary driving electrodes SD and secondary detection electrodes SPO are arranged at a circumferential distance of 90 degrees.

[0161] The vibration-type gyroscope element 100 shown in this modified example has the same effect as the structure shown in the first embodiment. That is, when the switching operation between the primary side and the secondary side is performed using the angular velocity sensor 1000, the bias component included in the output signal of the vibration-type gyroscope element 100 can be reduced.

[0162] Furthermore, in this modified example, the two secondary detection electrodes SPO are arranged at a circumferential distance of 90 degrees from each other, that is, at a position orthogonal to each other. Therefore, as explained in the first embodiment, the error component, i.e., the second harmonic component, contained in the output signal of the secondary detection electrode SPO can be reduced.

[0163] Furthermore, the angular velocity sensor 1000, which is equipped with the vibration-type gyroscope element 100 of this modified example, has the same structure as that shown in the first embodiment, and can improve the detection accuracy of angular velocity.

[0164] <Variation Example 4>

[0165] Figure 13 This is a top view showing the electrode arrangement involved in this modified example. A combination of primary driving electrode PD and primary detection electrode PPO, and a combination of secondary driving electrode SD and secondary detection electrode SPO are respectively provided, which is different from the structure shown in the first embodiment.

[0166] exist Figure 13 In the structure shown, a combination of a primary driving electrode PD and a primary detection electrode PPO and a secondary driving electrode SD and a secondary detection electrode SPO are arranged at a distance of (360 / 4N) degrees from each other in the circumferential direction. In this case, they are arranged at a distance of 45 degrees from each other in the circumferential direction.

[0167] The vibration-type gyroscope element 100 shown in this modified example has the same effect as the structure shown in the first embodiment. That is, when the switching operation between the primary side and the secondary side is performed using the angular velocity sensor 1000, the bias component included in the output signal of the vibration-type gyroscope element 100 can be reduced.

[0168] Furthermore, the angular velocity sensor 1000, which is equipped with the vibration-type gyroscope element 100 of this modified example, has the same structure as that shown in the first embodiment, and can improve the detection accuracy of angular velocity.

[0169] (Second Implementation)

[0170] Figure 14 This is a simplified structural diagram of the angular velocity sensor involved in this embodiment. The angular velocity sensor 2000 is composed of a pair of angular velocity sensors 1000 and 1100 and a computing unit 300.

[0171] A pair of angular velocity sensors 1000 and 1100 each have a vibrating gyroscope element 100 with the same structure and size. This vibrating gyroscope element 100 has the same structure as the vibrating gyroscope element shown in the first embodiment. Furthermore, the structure of the part processing the electrical signal is the same as... Figure 4 The structures shown are identical, with the structure and characteristics of each part being the same in the two angular velocity sensors 1000 and 1100. Furthermore, the two angular velocity sensors 1000 and 1100, and particularly the vibration-type gyroscope elements 100 respectively disposed in these two angular velocity sensors, are positioned close to each other, for example, disposed on the same substrate. Alternatively, even if disposed on different substrates, they are arranged within the same package or housing.

[0172] On the other hand, the pair of angular velocity sensors 1000 and 1100 operate in different ways. Angular velocity sensor 1000 operates by switching between the primary and secondary sides at a predetermined cycle. That is, it operates in the same way as the angular velocity sensor 1000 shown in the first embodiment. However, in this angular velocity sensor 1000, the switching cycle of the operating mode is constant.

[0173] On the other hand, the angular velocity sensor 1100 operates with the primary and secondary sides fixed. That is, no switching action is performed between the primary and secondary sides. Therefore, in the angular velocity sensor 1100, [the necessary step] can be omitted. Figure 4 The switching unit 250 and switch 260 are shown.

[0174] The output signals of angular velocity sensor 1000 and angular velocity sensor 1100 are respectively input to the arithmetic unit 300.

[0175] The arithmetic unit 300 corrects the output signal of the angular velocity sensor 1100 based on the output signal of the angular velocity sensor 1000, and calculates the angular velocity based on the corrected signal. Specifically, a bias component can be extracted from the output signal of the angular velocity sensor 1000, and the extracted bias component can be subtracted from the output signal of the angular velocity sensor 1100. It should be noted that the bias component can be obtained by adding the output signals of the angular velocity sensor 1000 when switching between the primary and secondary sides. Alternatively, as shown in the first embodiment, the output signal of the angular velocity sensor 1000, after the bias component has been eliminated, can be compared with the output signal of the angular velocity sensor 1100, the bias component contained in the output signal of the angular velocity sensor 1100 can be calculated, and then the correction can be performed by subtracting the bias component.

[0176] In the angular velocity sensor 1000 shown in the first embodiment, when the angular velocity sensor 1000 is mounted on a moving body, it is sometimes impossible to properly set the switching time between the primary and secondary sides. Furthermore, depending on the operating state of the device on which the angular velocity sensor 1000 is mounted, it is sometimes necessary to continuously output angular velocity from the angular velocity sensor 1000. In these cases, the bias component cannot be properly eliminated, which may lead to a decrease in the detection accuracy of the angular velocity.

[0177] On the other hand, according to this embodiment, the output signal of the angular velocity sensor 1100, which performs a switching operation between the primary side and the secondary side with a constant period, is used to correct the output signal of the angular velocity sensor 1100, which does not perform a switching operation.

[0178] In this way, regardless of the installation status of the angular velocity sensor 1100 or the operating status of the equipment, the bias component contained in the output signal of the angular velocity sensor 1100 can be determined, and the bias component can be appropriately and reliably reduced. In addition, the detection accuracy of angular velocity can be improved.

[0179] It should be noted that, in Figure 14 The example shown is an example where the arithmetic unit 300 is disposed externally to the two angular velocity sensors 1000 and 1100. However, the functions of the arithmetic unit 300 can also be incorporated into the arithmetic unit 240 disposed inside the angular velocity sensor 1000. This simplifies the structure of the angular velocity sensor 2000. In addition, it can reduce the cost of the angular velocity sensor 2000.

[0180] It should be noted that, in the above description, when the angular velocity sensor 1000 is operating, it operates by switching between the primary drive electrode PD and the secondary drive electrode SD at a predetermined cycle, and also by switching between the primary detection electrode PPO and the secondary detection electrode SPO. However, the combination of the electrodes 40 being switched is not limited to this. When the angular velocity sensor 1000 is operating, it is also possible to switch between the primary drive electrode PD and the secondary detection electrode SPO at a predetermined cycle, and also to switch between the primary detection electrode PPO and the secondary drive electrode SD.

[0181] (Other implementation methods)

[0182] New embodiments can also be constructed by appropriately combining the constituent elements shown in the first and second embodiments and their variations. For example, in the angular velocity sensors 1000 and 1100 shown in the second embodiment, the vibrating gyroscope element 100 shown in any of the variations 1 to 4 can also be used as the vibrating gyroscope element 100 respectively installed in the angular velocity sensors 1000 and 1100. However, in this case, it is preferable that the two vibrating gyroscope elements 100 have the same structure and size.

[0183] Furthermore, in the first and second embodiments and various modifications, an electromagnetic vibration type gyroscope element 100 was described as an example, but it is not particularly limited to this. For example, the structure disclosed herein can also be applied to a piezoelectric vibration type gyroscope element.

[0184] Figure 15 This is a top view showing a piezoelectric vibrating gyroscope element. Figure 16 It is shown Figure 15 A cross-sectional view at line XVI-XVI.

[0185] exist Figure 15 In the vibration-type gyroscope element 120 shown, the structure and arrangement of the fixing part 10, the oscillator 20, and the support part 30 are the same as those in the vibration-type gyroscope element 100 shown in the first embodiment. The arrangement of the primary drive electrode PD, the primary detection electrode PPO, the secondary drive electrode SD, and the secondary detection electrode SPO is also the same as in the first embodiment.

[0186] On the other hand, Figure 15 , Figure 16 The vibration-type gyroscope element 120 shown omits the magnetic field application section 60, and the plurality of electrodes 70a to 70p are piezoelectric structures 80 formed by sequentially stacking a lower electrode layer 83, a piezoelectric body layer 82 and an upper electrode layer 81, which differs from the vibration-type gyroscope element 100 shown in the first embodiment.

[0187] Figure 15 The vibrating gyroscope element 120 shown operates as follows. First, at the primary drive electrode PD, when an AC voltage is applied between the upper electrode layer 81 and the lower electrode layer 83, the piezoelectric layer 82 periodically expands and contracts. Corresponding to this expansion and contraction, the oscillator 20 vibrates. The primary vibration of the cos2θ mode is excited on the oscillator 20 by aligning the frequency of the AC voltage with the resonant frequency of the oscillator 20, which is the same as in the first embodiment. Furthermore, the primary vibration is stabilized by feeding back the output signal of the primary detection unit 210 to the primary AC power supply 200, which is also the same as in the first embodiment.

[0188] In addition, in response to the vibration of the oscillator 20, the secondary detection electrode SPO and its piezoelectric layer 82 expand and contract. Corresponding to this expansion and contraction, an alternating voltage is generated between the upper electrode layer 81 and the lower electrode layer 83 contained in the secondary detection electrode SPO.

[0189] When the oscillator 20 generates an angular velocity and undergoes secondary vibration, the voltage signal generated by the secondary detection electrode SPO is input to the secondary detection unit 230. Based on the output signal of the secondary detection unit 230, the output of the secondary AC power supply 220 is controlled to cancel the secondary vibration. The angular velocity is calculated by the arithmetic unit 240 based on the output signal of the secondary AC power supply 220, which is the same as in the first embodiment.

[0190] exist Figure 15 In the vibrating gyroscope element 120 shown, it is obvious that the bias component contained in the voltage generated by the secondary detection electrode SPO can be reduced in the same way as in the vibrating gyroscope element shown in the first embodiment. In addition, the angular velocity sensor 1000 equipped with this vibrating gyroscope element 120 can improve the detection accuracy of angular velocity, which is also the same as in the vibrating gyroscope element shown in the first embodiment.

[0191] Additionally, if also considered Figure 15 As shown in the example, the primary AC power supply 200 described in this application applies AC current of a specified frequency to the primary drive electrode PD. Additionally, the secondary AC power supply 220 applies AC current to the secondary drive electrode SD.

[0192] It should be noted that the oscillator 20 can be any shape that is excited to undergo primary vibration and whose vibration state changes when angular velocity is generated; it is not particularly limited to a ring shape. For example, it can also be a regular polygonal ring or a disk shape. Alternatively, it can be hemispherical.

[0193] Furthermore, the support portion 30 is not limited to any shape, as long as it can connect the oscillator 20 to the fixing portion 10 without hindering the vibration of the oscillator 20. Figure 1 , Figure 3 The shape shown.

[0194] Furthermore, in the first and second embodiments and their variations, examples are shown where the primary driving electrode PD and the primary detection electrode PPO are arranged side-by-side on the front of the oscillator 20 and the support portion 30. However, this is not particularly limiting; for example, they may also be arranged side-by-side with a gap between them in the thickness direction of the oscillator 20 and the support portion 30. Specifically, one of the primary driving electrode PD and the primary detection electrode PPO may be located on the front of the oscillator 20 and the support portion 30, while the other is located on the back of the oscillator 20 and the support portion 30. Similarly, the secondary driving electrode SD and the secondary detection electrode SPO may also be arranged side-by-side with a gap between them in the thickness direction of the oscillator 20 and the support portion 30. That is, one of the secondary driving electrode SD and the secondary detection electrode SPO may be located on the front of the oscillator 20 and the support portion 30, while the other is located on the back of the oscillator 20 and the support portion 30. Alternatively, these electrodes may be arranged inside the oscillator 20 and the support portion 30.

[0195] -Industry Applicability-

[0196] The vibration-type gyroscope element disclosed herein can reduce the bias component contained in the output signal, and is therefore useful in applications such as high-precision angular velocity sensors.

[0197] - Symbol Explanation -

[0198] 10. Fixing part

[0199] 20 oscillators

[0200] 30 Support section

[0201] 40a~40p electrode

[0202] 51 First silicon layer

[0203] 52 Silicon oxide layer

[0204] 53 Second silicon layer

[0205] 54 Silica film

[0206] 60 Magnetic field application section

[0207] 61 Upper yoke

[0208] 62 magnets

[0209] 63 lower yoke

[0210] 70a~70p electrodes

[0211] 80 Piezoelectric Structure

[0212] 81 Upper electrode layer

[0213] 82 Piezoelectric layer

[0214] 83 Lower electrode layer

[0215] 100, 110, 120 vibration type gyroscope elements

[0216] 200 primary AC power supply

[0217] 210 Primary Testing Department

[0218] 220 secondary AC power supply

[0219] 230 Secondary Testing Department

[0220] 240 Computing Unit

[0221] 250 Switching Unit

[0222] 260 switch

[0223] 300 Computing Unit

[0224] 1000 angular velocity sensor

[0225] 1100 angular velocity sensor

[0226] 2000 angular velocity sensor.

Claims

1. A vibrating gyroscope element, characterized in that: The vibrating gyroscope element includes at least a fixed part, an oscillator, a support part, and electrodes. The support portion connects the oscillator to the fixing portion and supports the oscillator in a manner that allows it to vibrate. The electrodes are formed in the plane of the oscillator. When the oscillator has a vibration mode of cosNθ and N is a natural number greater than 2, The electrodes are arranged in 4N directions, and the axes of the electrodes are arranged at equal angular intervals along the outer periphery of the oscillator. The plurality of electrodes includes a primary driving electrode, a primary detection electrode, a secondary detection electrode, and a secondary driving electrode. The primary driving electrode excites primary vibrations of the cosNθ mode on the oscillator. The primary detection electrode detects the primary vibration. The secondary detection electrode detects the secondary vibration of the oscillator. The secondary drive electrode drives the oscillator to counteract the secondary vibration. The primary detection electrode and the primary driving electrode are arranged in the same orientation. The secondary driving electrode and the secondary detection electrode are arranged in the same orientation. The combination of the primary driving electrode and the primary detection electrode, and the combination of the secondary driving electrode and the secondary detection electrode, are included in the same number of the plurality of electrodes. The two electrodes are formed such that they extend side-by-side in a ring shape from the support portion, spaced apart from each other, and further wherein one electrode surrounds the other electrode on its inner side, or the other electrode surrounds one electrode on its inner side. One electrode disposed on one of the support portions is the primary driving electrode, and the other electrode disposed on the same support portion is the primary detection electrode. One of the electrodes disposed on another support portion is the secondary drive electrode, and the other electrode disposed on the same support portion is the secondary detection electrode.

2. The vibration-type gyroscope element according to claim 1, characterized in that: The secondary detection electrodes arranged at positions (360 / 2N + 360 × (M / N)) degrees apart in the outer circumferential direction of the oscillator are provided in one or more sets, where M is an integer and 0 ≤ M ≤ N-1.

3. The vibrating gyroscope element according to claim 1 or 2, characterized in that: The vibrating gyroscope element further includes a magnetic field applying section, which applies a magnetic field to a plurality of electrodes along a direction intersecting the front of the oscillator.

4. An angular velocity sensor, characterized in that: The angular velocity sensor includes at least the vibration-type gyroscope element as described in any one of claims 1 to 3, a primary AC power supply, a primary detection unit, a secondary AC power supply, a secondary detection unit, and a computing unit. The primary AC power supply applies AC current of a specified frequency to the primary driving electrode. The primary detection unit detects the voltage signal generated by the primary detection electrode. The secondary AC power supply applies AC current to the secondary drive electrode. The secondary detection unit detects the voltage signal generated by the secondary detection electrode. The arithmetic unit calculates the angular velocity based on the output signal of the secondary AC power supply.

5. The angular velocity sensor according to claim 4, characterized in that: By feeding back the output signal of the primary detection unit to the primary AC power supply, the primary vibration generated by the oscillator is stabilized. The output of the secondary AC power supply is controlled based on the output signal of the secondary detection unit, thereby canceling out the secondary vibration generated by the oscillator. The arithmetic unit calculates the angular velocity based on the output signal of the secondary AC power supply.

6. The angular velocity sensor according to claim 4, characterized in that: The angular velocity sensor further includes a switching unit that switches the primary driving electrode to the secondary driving electrode or the secondary detection electrode at predetermined times, and also switches the primary detection electrode to the secondary detection electrode or the secondary driving electrode. The arithmetic unit calculates the angular velocity based on the output signal of the secondary AC power supply before and after the switching action.

7. The angular velocity sensor according to claim 6, characterized in that: The angular velocity sensor includes a pair of angular velocity sensors. One of the pair of angular velocity sensors is the angular velocity sensor according to claim 6. This angular velocity sensor operates by switching between the primary driving electrode and the secondary driving electrode or the secondary detection electrode at a predetermined period, and also by switching between the primary detection electrode and the secondary detection electrode or the secondary driving electrode. The other angular velocity sensor in the pair of angular velocity sensors does not switch. The bias component contained in the output signal of one angular velocity sensor is used to correct the output signal of the other angular velocity sensor, and the angular velocity is calculated.

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