gyroscope

Abstract

In this gyroscope (100), a secondary drive circuit (SDC) in a non-inverting mode is provided with a range-switching element (32a) for switching a current range for driving a secondary drive electrode (SD). In addition, a primary drive circuit (PDC) in a non-inverting mode is provided with a circuit symmetry element (31a) for obtaining symmetry of the secondary drive circuit (SDC) before and after electrical inversion control in an inverting mode. The circuit symmetry element (31a) is provided at a position corresponding to the range-switching element (32a) and has the same structure as the range-switching element (32a).

Description

Gyroscope

[0001] The present invention relates to a gyroscope equipped with a vibration type gyro element.

[0002] Gyroscopes equipped with a vibration-type gyro element have been known in the past, and such gyroscopes are disclosed, for example, in Japanese Patent Application Laid-Open No. 2009-115559.

[0003] Japanese Patent Application Laid-Open Publication No. 2009-115559 discloses a gyroscope equipped with a vibrating gyro element. The vibrating gyro element includes a ring-shaped element (vibrator), a primary drive electrode that generates primary vibration in the element, a primary detection electrode that detects the primary vibration, a secondary detection electrode that detects secondary vibration of the element caused by an angular velocity applied to the element, and a secondary drive electrode that drives the element to cancel out the secondary vibration. The primary drive electrode constitutes a primary drive circuit. The secondary drive electrode constitutes a secondary drive circuit.

[0004] Furthermore, the gyroscope disclosed in JP 2009-115559 A includes a processor (controller) that performs control to detect angular velocity based on output signals to secondary drive electrodes. The processor performs electrical inversion control to swap the functions of the primary drive circuit and the secondary drive circuit, and to swap the functions of the primary detection electrodes and the secondary detection electrodes, and also performs control to detect angular velocity based on the difference between the output signals to the secondary drive electrodes before and after the electrical inversion control. By calculating the difference between the output signals to the secondary drive electrodes before and after the electrical inversion control, bias components generated by various factors such as circuit characteristics are canceled.

[0005] JP 2009-115559 A

[0006] Although not explicitly stated in JP 2009-115559 A, a gyroscope such as that described therein may be used for two purposes: detecting the azimuth angle of an article on which the gyroscope is mounted based on the detected angular velocity of the Earth's rotation, and detecting an attitude angle based on the detected angular velocity associated with changes in the attitude of the article on which the gyroscope is mounted. When detecting the azimuth angle of an article on which the gyroscope is mounted based on the detected angular velocity of the Earth's rotation, a relatively small angular velocity detection range is required, but the angular velocity detection accuracy is relatively high. When detecting the attitude angle based on the detected angular velocity associated with changes in the attitude of the article on which the gyroscope is mounted, a relatively low angular velocity detection accuracy is required, but the angular velocity detection range is relatively large. When a single gyroscope is used for the above two purposes, a gyroscope such as that described in JP 2009-115559 A is generally configured as follows. That is, the control unit is configured to switch between an inversion mode in which angular velocity is detected based on the difference between the output signals to the secondary drive electrodes before and after electrical inversion control, and a non-inversion mode in which angular velocity is detected based on the output signals to the secondary drive electrodes without performing electrical inversion control. Also, the secondary drive circuit in the non-inversion mode is provided with a range switching element for switching the current range or voltage range for driving the secondary drive electrodes.

[0007] However, in the above configuration, the symmetry of the secondary drive circuit before and after electrical inversion control in the inversion mode is reduced due to the characteristics (stray capacitance) of the range switching element provided in the secondary drive circuit in the non-inversion mode. In this case, a difference occurs in the bias component of the output signal to the secondary drive electrodes before and after electrical inversion control in the inversion mode. Therefore, it becomes impossible to properly cancel the bias component by differentiating the output signal to the secondary drive electrodes before and after electrical inversion control in the inversion mode. Therefore, there is a need for a gyroscope that can switch between an inversion mode in which electrical inversion control is performed and a non-inversion mode in which electrical inversion control is not performed, and that can prevent the inability to properly cancel the bias component by differentiating the output signal to the secondary drive electrodes before and after electrical inversion control in the inversion mode in a configuration in which a range switching element is provided in the secondary drive circuit in the non-inversion mode.

[0008] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a gyroscope that can switch between an inversion mode in which electrical inversion control is performed and a non-inversion mode in which electrical inversion control is not performed, and that can prevent the bias component from being unable to be properly canceled by differentiating the output signals to the secondary drive electrodes before and after electrical inversion control in the inversion mode, in a configuration in which a range switching element is provided in the secondary drive circuit in the non-inversion mode.

[0009] In order to achieve the above object, a gyroscope according to one aspect of the present invention comprises a vibrating gyro element including a vibrator, a primary drive electrode that generates a primary vibration in the vibrator, a primary detection electrode that detects the primary vibration, a secondary detection electrode that detects a secondary vibration of the vibrator caused by an angular velocity applied to the vibrator, and a secondary drive electrode that drives the vibrator so as to cancel the secondary vibration, and a control unit that performs control to detect the angular velocity based on an output signal to the secondary drive electrode, wherein the primary drive electrode constitutes a primary drive circuit and the secondary drive electrode constitutes a secondary drive circuit, and the control unit performs electrical inversion control to exchange the function of the primary drive circuit with the function of the secondary drive circuit and to exchange the function of the primary detection electrode with the function of the secondary detection electrode. The secondary drive circuit is configured to switch between an inversion mode in which angular velocity is detected based on the difference between the output signals to the secondary drive electrodes before and after electrical inversion control, and a non-inversion mode in which angular velocity is detected based on the output signals to the secondary drive electrodes without performing electrical inversion control. In the non-inversion mode, the secondary drive circuit is provided with a range switching element for switching the current range or voltage range for driving the secondary drive electrodes, and in the non-inversion mode, a circuit symmetry element is provided in the primary drive circuit to achieve symmetry of the secondary drive circuit before and after electrical inversion control in the inversion mode. The circuit symmetry element is provided in a position corresponding to the range switching element and has the same structure as the range switching element.

[0010] In a gyroscope according to one aspect of the present invention, as described above, the secondary drive circuit in the non-inverting mode is provided with a range switching element for switching the current range or voltage range for driving the secondary drive electrodes, and the primary drive circuit in the non-inverting mode is provided with a circuit symmetry element for achieving symmetry of the secondary drive circuit before and after electrical inversion control in the inverting mode, the circuit symmetry element being provided at a position corresponding to the range switching element and having the same structure as the range switching element. This makes it possible to prevent the symmetry of the secondary drive circuit before and after electrical inversion control in the inverting mode from being reduced (the stray capacitance on the secondary drive circuit before and after electrical inversion control in the inverting mode being different) compared to when the primary drive circuit in the non-inverting mode does not have a circuit symmetry element. Furthermore, since the circuit symmetry element is provided at a position corresponding to the range switching element and has the same structure as the range switching element, the characteristics (stray capacitance) of the circuit symmetry element are close to the characteristics (stray capacitance) of the range switching element, which reliably prevents the symmetry of the secondary drive circuit before and after electrical inversion control in the inversion mode from decreasing (i.e., the stray capacitances on the secondary drive circuit are different before and after electrical inversion control in the inversion mode). This prevents a difference in the bias component of the output signal to the secondary drive electrode before and after electrical inversion control in the inversion mode. As a result, in a configuration in which switching is performed between an inversion mode in which electrical inversion control is performed and a non-inversion mode in which electrical inversion control is not performed and in which a range switching element is provided in the secondary drive circuit in the non-inversion mode, it is possible to prevent an inability to properly cancel the bias component by differentiating the output signal to the secondary drive electrode before and after electrical inversion control in the inversion mode.

[0011] In the gyroscope according to the above aspect, preferably, the secondary drive circuit in the non-inverting mode is provided with a secondary amplifier that outputs a current or voltage for driving the secondary drive electrodes, the primary drive circuit in the non-inverting mode is provided with a primary amplifier that outputs a current or voltage for driving the primary drive electrodes, the secondary amplifier and the primary amplifier are configured to switch their functions before and after electrical inversion control in the inverting mode, the range switching element is a switch provided to bypass a resistor provided on the input side of the secondary amplifier in the non-inverting mode, the circuit symmetry element is a switch provided to bypass the resistor provided on the input side of the primary amplifier in the non-inverting mode and is provided in a position corresponding to the switch serving as the range switching element, and the switch serving as the circuit symmetry element has the same structure as the switch serving as the range switching element. With this configuration, it is possible to easily realize a configuration in which the circuit symmetry element is provided in a position corresponding to the range switching element and has the same structure as the range switching element.

[0012] The gyroscope according to the above aspect preferably further comprises a secondary AC power supply that supplies AC current as an output signal to the secondary drive electrode so as to cancel out the secondary vibration, and a primary AC power supply that supplies AC current to the primary drive electrode, wherein the secondary drive circuit in the non-inverting mode is provided with a secondary amplifier that outputs a current or a voltage for driving the secondary drive electrode, and the primary drive circuit in the non-inverting mode is provided with a primary amplifier that outputs a current or a voltage for driving the primary drive electrode, and in the inverting mode, the secondary amplifier and the primary amplifier are configured to exchange functions with each other before and after electrical inversion control, and a plurality of secondary-side branch circuit sections that are parallel circuits including resistors of different resistance values ​​are provided between the range switching element and the secondary amplifier, and the secondary-side branch circuit sections are configured to exchange functions with the circuit symmetry element. Between the secondary amplifier and the secondary power amplifier, there are provided a plurality of primary-side branch circuits, each of which is a parallel circuit including resistors with different resistance values. The plurality of secondary-side branch circuits and the plurality of primary-side branch circuits have the same structure, and the resistors of the plurality of secondary-side branch circuits and the plurality of primary-side branch circuits have the same resistance values. The range switching element is a switch configured to switch which of the plurality of secondary-side branch circuits is connected to a secondary AC power source. The circuit symmetry element is a switch configured not to switch which of the plurality of primary-side branch circuits is connected to a primary AC power source. The switch as the circuit symmetry element is located at a position corresponding to the switch as the range switching element and has the same structure as the switch as the range switching element. This configuration makes it easy to realize a configuration in which the circuit symmetry element is located at a position corresponding to the switch as the range switching element and has the same structure as the switch as the range switching element. Furthermore, stray capacitance exists in the primary-side branch circuit not connected to the primary AC power source, and parasitic capacitance exists in the primary-side branch circuit connected to the primary AC power source. Furthermore, stray capacitance exists in the secondary branch circuit portion that is not connected to the secondary AC power supply, and parasitic capacitance exists in the secondary branch circuit portion that is connected to the secondary AC power supply.Because the secondary AC power supply is connected to one of the multiple secondary branch circuits, stray capacitance or parasitic capacitance exists in all secondary branch circuits, regardless of which secondary branch circuit the secondary AC power supply is connected to. This makes it possible to equalize the influence of the stray capacitance and parasitic capacitance present in the secondary branch circuits with the influence of the stray capacitance and parasitic capacitance present in the primary branch circuits. As a result, it is possible to prevent the symmetry of the secondary drive circuit before and after electrical reversal control in the reversal mode from decreasing immediately after switching the angular velocity detection range and switching from the non-reversal mode to the reversal mode.

[0013] In the configuration in which the range switching element is a switch and the circuit symmetry element is a switch, it is preferable to further include a range switching switch power supply connected to the switch as the range switching element, and a circuit symmetry switch power supply connected to the switch as the circuit symmetry element. With this configuration, it is possible to more effectively prevent the symmetry of the secondary drive circuit from decreasing before and after electrical reversal control in the reversal mode, compared to a configuration in which a circuit symmetry switch power supply connected to the switch as the circuit symmetry element is not provided.

[0014] In a configuration in which the range switching element is a switch provided to bypass a resistor provided on the input side of the secondary amplifier in the non-inverting mode and the circuit symmetry element is a switch provided to bypass a resistor provided on the input side of the primary amplifier in the non-inverting mode, preferably the circuit further includes a range switching control unit for switching the switch as the range switching element between an OFF state and an ON state, the range switching control unit being configured to use the switch as the range switching element in the ON state in the non-inverting mode to increase the amplification factor of the secondary amplifier compared to when the switch as the range switching element is OFF, and to use the switch as the range switching element in the OFF state in the inverting mode to equalize the amplification factors of the secondary amplifier and the primary amplifier, and the switch as the circuit symmetry element is always used only in the OFF state to equalize the amplification factors of the secondary amplifier and the primary amplifier. With this configuration, there is no need for a switch control unit for switching the switch as the circuit symmetry element between an OFF state and an ON state, thereby reducing the number of components and simplifying the circuit configuration.

[0015] In a configuration in which the range switching element is a switch configured to be able to switch the secondary-side branch circuit to which the secondary AC power supply is connected and the circuit symmetry element is a switch configured not to switch the primary-side branch circuit to which the primary AC power supply is connected, preferably the power supply further includes a range switching switch control unit that controls the switch as the range switching element to switch the secondary-side branch circuit to which the secondary AC power supply is connected, and the range switching switch control unit is configured to control the switch as the range switching element to connect the secondary AC power supply to the secondary-side branch circuit having the smallest resistance in the non-inverting mode, thereby making the amplification factor of the secondary amplifier larger than that in a state in which the secondary AC power supply is connected to a secondary-side branch circuit having another resistance, and to control the switch as the range switching element to connect the secondary AC power supply to the secondary-side branch circuit having the largest resistance in the inverting mode, thereby making the amplification factors of the secondary amplifier and the primary amplifier equal, and the switch as the circuit symmetry element is configured to make the amplification factors of the secondary amplifier and the primary amplifier equal by always connecting the primary AC power supply to the primary-side branch circuit having the largest resistance. With this configuration, the secondary drive electrodes can be driven in a relatively small current range or voltage range in the inversion mode and in a relatively large current range or voltage range in the non-inversion mode. This allows the output signals to the secondary drive electrodes before and after the electrical inversion control to be relatively small in the inversion mode and relatively large in the non-inversion mode. As a result, a configuration can be reliably realized in which, although the angular velocity detection range based on the output signals to the secondary drive electrodes before and after the electrical inversion control is relatively small in the inversion mode, the angular velocity detection accuracy based on the output signals to the secondary drive electrodes before and after the electrical inversion control is relatively high, and, although the angular velocity detection accuracy based on the output signals to the secondary drive electrodes is relatively low in the non-inversion mode, the angular velocity detection range based on the output signals to the secondary drive electrodes is relatively large.

[0016] In the configuration in which the range switching element is a switch and the circuit symmetry element is a switch, the switch serving as the circuit symmetry element is preferably a switch from the same production lot as the switch serving as the range switching element. This configuration allows the characteristics (stray capacitance) of the switch serving as the circuit symmetry element to be closer to the characteristics of the switch serving as the range switching element, compared to when the switch serving as the circuit symmetry element is not from the same production lot as the switch serving as the range switching element. This further reduces the symmetry of the secondary drive circuit before and after electrical reversal control in the reversal mode, compared to when the switch serving as the circuit symmetry element is not from the same production lot as the switch serving as the range switching element.

[0017] In the gyroscope according to the above aspect, the circuit symmetry element is preferably not electrically controlled, and the range switching element switches the current range or voltage range in response to switching between the inverting mode and the non-inverting mode, so that the secondary drive electrodes are driven in a first current range or a first voltage range before and after the electrical inversion control in the inverting mode, and are driven in a second current range larger than the first current range or a second voltage range larger than the first voltage range in the non-inverting mode. With this configuration, the output signal to the secondary drive electrodes before and after the electrical inversion control can be made relatively small in the inverting mode, and the output signal to the secondary drive electrodes can be made relatively large in the non-inverting mode. As a result, in the inversion mode, although the detection range of the angular velocity based on the output signal to the secondary drive electrode before and after the electrical inversion control is relatively small, the detection accuracy of the angular velocity based on the output signal to the secondary drive electrode before and after the electrical inversion control is relatively high, and in the non-inversion mode, although the detection accuracy of the angular velocity based on the output signal to the secondary drive electrode is relatively low, it is possible to reliably realize a configuration in which the detection range of the angular velocity based on the output signal to the secondary drive electrode is relatively large.

[0018] According to the present invention, as described above, in a configuration in which switching is performed between an inversion mode in which electrical inversion control is performed and a non-inversion mode in which electrical inversion control is not performed, and in which a range switching element is provided in the secondary drive circuit in the non-inversion mode, it is possible to prevent the bias component from being unable to be properly canceled by differentiating the output signals to the secondary drive electrode before and after electrical inversion control in the inversion mode.

[0019] 10 is a block diagram showing the configuration of a gyroscope according to a first embodiment. FIG. 11 is a plan view showing primary vibration of a vibrator of the gyroscope according to the first embodiment. FIG. 12 is a plan view showing secondary vibration of a vibrator of the gyroscope according to the first embodiment. FIG. 13 is a block diagram showing the configuration of a gyroscope in a state after electrical inversion control has been performed from the state of FIG. 1. FIG. 14 is a diagram for explaining the inversion mode and non-inversion mode of the gyroscope according to the first embodiment. FIG. 15 is a circuit diagram showing a first drive circuit and a second drive circuit in the non-inversion mode of the gyroscope according to the first embodiment. FIG. 16 is a circuit diagram showing the first drive circuit and the second drive circuit in a state before electrical inversion control is performed in the inversion mode of the gyroscope according to the first embodiment. FIG. 17 is a circuit diagram showing the first drive circuit and the second drive circuit in a state after electrical inversion control has been performed in the inversion mode of the gyroscope according to the first embodiment. FIG. 18 is a block diagram showing the configuration of a gyroscope according to a second embodiment. FIG. 19 is a block diagram showing the configuration of a gyroscope in a state after electrical inversion control has been performed from the state of FIG. 10. FIG. 11 is a circuit diagram showing the first drive circuit and the second drive circuit in the non-inversion mode of the gyroscope according to the second embodiment. 10A and 10B are circuit diagrams showing the first and second drive circuits before and after electrical inversion control is performed in the inversion mode of the gyroscope according to the second embodiment;

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] 1 to 8, the configuration of a gyroscope 100 according to a first embodiment of the present invention will be described. The gyroscope 100 is a device that detects the azimuth angle of an article on which the gyroscope 100 is mounted based on the detected angular velocity of the Earth's rotation, and detects the attitude angle based on the detected angular velocity associated with a change in attitude of the article on which the gyroscope 100 is mounted. The gyroscope 100 is a MEMS (Micro Electro Mechanical Systems) device.

[0022] (Overall Configuration of Gyroscope) As shown in FIG. 1, the gyroscope 100 includes a vibration type gyro element 10 and a control unit 20.

[0023] <Configuration of Vibration Gyro Element> As shown in Fig. 1, the vibration gyro element 10 includes a vibrator 11, a first electrode 12a, a second electrode 12b, a third electrode 12c, and a fourth electrode 12d. The first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d are arranged on the surface of the vibrator 11. Note that Fig. 1 shows a state in which the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d function as a primary drive electrode PD, a primary detection electrode PPO, a secondary detection electrode SPO, and a secondary drive electrode SD, respectively. In other words, the vibration gyro element 10 includes a primary drive electrode PD, a primary detection electrode PPO, a secondary detection electrode SPO, and a secondary drive electrode SD.

[0024] The vibrator 11 is formed in a circular ring shape. That is, the vibrator 11 is formed in a ring shape having a rotationally symmetric shape. The primary drive electrode PD is an electrode that generates a primary vibration, which will be described later, in the vibrator 11. The primary detection electrode PPO is an electrode that detects the primary vibration. The secondary detection electrode SPO is an electrode that detects a secondary vibration, which will be described later, of the vibrator 11 caused by an angular velocity applied to the vibrator 11. The secondary drive electrode SD is an electrode that drives the vibrator 11 so as to cancel out the secondary vibration.

[0025] As shown in Fig. 2, the vibrator 11 periodically undergoes primary vibrations in an elliptical shape having mutually orthogonal principal axes. Fig. 2 shows an example in which the vibrator 11 undergoes primary vibrations in a cos2θ vibration mode. Furthermore, as shown in Fig. 3, secondary vibrations are generated in a 45-degree direction from the principal axis of the primary vibration due to the Coriolis force generated by applying an angular velocity to the vibrator 11.

[0026] 1, the control unit 20 includes a primary AC power supply 21, a primary detection unit 22, a secondary detection unit 23, and a secondary AC power supply 24. The primary AC power supply 21 supplies AC current to the primary drive electrode PD. A voltage signal based on the primary vibration detected by the primary detection electrode PPO is input to the primary detection unit 22 from the primary detection electrode PPO. A voltage signal based on the secondary vibration detected by the secondary detection electrode SPO is input to the secondary detection unit 23 from the secondary detection electrode SPO. The secondary AC power supply 24 supplies AC current to the secondary drive electrode SD.

[0027] <Configuration of Primary Control Circuit> As shown in FIG. 1, in the gyroscope 100, the primary drive electrodes PD, the primary detection electrodes PPO, the primary AC power supply 21, and the primary detection unit 22 configure the primary control circuit PC.

[0028] Specifically, when an AC current is supplied to the primary drive electrode PD from the primary AC power supply 21, a Lorentz force is generated in the primary drive electrode PD in a direction intersecting the direction of the magnetic field applied from a magnetic field application unit (not shown) and the direction of the AC current. The vibrator 11 on which the primary drive electrode PD is disposed is deformed by the Lorentz force generated in the primary drive electrode PD. The direction of the Lorentz force generated in the primary drive electrode PD is periodically reversed depending on the frequency of the AC current supplied to the primary drive electrode PD. As a result, the vibrator 11 undergoes primary vibration at the same frequency as the frequency of the AC current supplied to the primary drive electrode PD.

[0029] The primary detection electrode PPO detects the primary vibration of the vibrator 11. The primary detection electrode PPO generates a voltage signal based on the magnitude of the amplitude of the detected primary vibration. The voltage signal generated by the primary detection electrode PPO is output to a primary detection unit 22. The primary detection unit 22 outputs an output signal to a primary AC power supply 21 based on the voltage signal input from the primary detection electrode PPO. The primary AC power supply 21 controls the amplitude and frequency of the AC current supplied to the primary drive electrode PD based on the output signal input from the primary detection unit 22 so that the frequency and amplitude of the primary vibration of the vibrator 11 are constant. In other words, the primary control circuit PC performs feedback control so that the frequency and amplitude of the primary vibration of the vibrator 11 are constant.

[0030] <Configuration of Secondary Control Circuit> As shown in FIG. 1, in the gyroscope 100, the secondary detection electrodes SPO, the secondary drive electrodes SD, the secondary detection unit 23, and the secondary AC power supply 24 configure the secondary control circuit SC.

[0031] Specifically, the secondary detection electrode SPO detects the secondary vibration of the vibrator 11. The secondary detection electrode SPO generates a voltage signal based on the magnitude of the amplitude of the detected secondary vibration. The voltage signal generated by the secondary detection electrode SPO is output to the secondary detection unit 23. The secondary detection unit 23 outputs an output signal to the secondary AC power supply 24 based on the voltage signal input from the secondary detection electrode SPO. The secondary AC power supply 24 supplies an AC current to the secondary drive electrode SD (outputs an output signal to the secondary drive electrode SD) based on the output signal input from the secondary detection unit 23 so as to cancel out the secondary vibration generated in the vibrator 11. In other words, the secondary control circuit SC performs feedback control so as to suppress the secondary vibration of the vibrator 11.

[0032] The control unit 20 includes a calculation unit 25 for calculating the angular velocity of the vibrator 11. The calculation unit 25 receives an output signal that is the same as the output signal to the secondary drive electrode SD output from the secondary AC power supply 24. The calculation unit 25 then calculates the angular velocity based on the output signal output from the secondary AC power supply 24. That is, the control unit 20 detects the angular velocity based on the output signal to the secondary drive electrode SD.

[0033] (Electrical Reversal Control) As shown in Figures 1 and 4, the control unit 20 is configured to perform electrical reversal control to swap the functions of the primary drive circuit PDC and the secondary drive circuit SDC, and to swap the functions of the primary detection electrodes PPO and the secondary detection electrodes SPO.

[0034] 1 , the control unit 20 includes a first switch 26, a second switch 27, a third switch 28, and a fourth switch 29. The first switch 26 is configured to be switchable between a state in which the first electrode 12 a is connected to the primary AC power supply 21 and a state in which the first electrode 12 a is connected to the secondary AC power supply 24. The second switch 27 is configured to be switchable between a state in which the second electrode 12 b is connected to the primary detection unit 22 and a state in which the second electrode 12 b is connected to the secondary detection unit 23. The third switch 28 is configured to be switchable between a state in which the third electrode 12 c is connected to the secondary detection unit 23 and a state in which the third electrode 12 c is connected to the primary detection unit 22. The fourth switch 29 is configured to be switchable between a state in which the fourth electrode 12 d is connected to the secondary AC power supply 24 and a state in which the fourth electrode 12 d is connected to the primary AC power supply 21.

[0035] 1, the first electrode 12a is connected to the primary AC power supply 21 via a first switch 26, the second electrode 12b is connected to the primary detection unit 22 via a second switch 27, the third electrode 12c is connected to the secondary detection unit 23 via a third switch 28, and the fourth electrode 12d is connected to the secondary AC power supply 24 via a fourth switch 29. As a result, in the state of FIG. 1, as described above, the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d function as the primary drive electrode PD, the primary detection electrode PPO, the secondary detection electrode SPO, and the secondary drive electrode SD, respectively. 1 , a primary control circuit PC is configured by the first electrode 12 a functioning as the primary drive electrode PD, the second electrode 12 b functioning as the primary detection electrode PPO, the primary AC power supply 21, and the primary detection unit 22, and a secondary control circuit SC is configured by the third electrode 12 c functioning as the secondary detection electrode SPO, the fourth electrode 12 d functioning as the secondary drive electrode SD, the secondary detection unit 23, and the secondary AC power supply 24. Note that, in the state of FIG. 1 , a primary drive circuit PDC is configured by the first electrode 12 a functioning as the primary drive electrode PD and the first switch 26, and a secondary drive circuit SDC is configured by the fourth electrode 12 d functioning as the secondary drive electrode SD and the fourth switch 29. That is, the primary drive electrode PD configures the primary drive circuit PDC, and the secondary drive electrode SD configures the secondary drive circuit SDC.

[0036] The control unit 20 switches the connection states of the circuits in the first switch 26, the second switch 27, the third switch 28, and the fourth switch 29, thereby switching (performing electrical inversion control) between a state in which the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d are connected to the primary AC power supply 21, the primary detection unit 22, the secondary detection unit 23, and the secondary AC power supply 24, respectively (the state in FIG. 1 ), and a state in which the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d are connected to the secondary AC power supply 24, the secondary detection unit 23, the primary detection unit 22, and the primary AC power supply 21, respectively (the state in FIG. 4 ).

[0037] 4, the first electrode 12a is connected to the secondary AC power supply 24 via a first switch 26, the second electrode 12b is connected to the secondary detection unit 23 via a second switch 27, the third electrode 12c is connected to the primary detection unit 22 via a third switch 28, and the fourth electrode 12d is connected to the primary AC power supply 21 via a fourth switch 29. As a result, in the state of FIG. 4, the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d function as the secondary drive electrode SD, the secondary detection electrode SPO, the primary detection electrode PPO, and the primary drive electrode PD, respectively. 4 , the primary control circuit PC is formed by the fourth electrode 12 d functioning as the primary drive electrode PD, the third electrode 12 c functioning as the primary detection electrode PPO, the primary AC power supply 21, and the primary detection unit 22, while the secondary control circuit SC is formed by the second electrode 12 b functioning as the secondary detection electrode SPO, the first electrode 12 a functioning as the secondary drive electrode SD, the secondary detection unit 23, and the secondary AC power supply 24. In the state of FIG. 4 , the secondary drive circuit SDC is formed by the first electrode 12 a functioning as the secondary drive electrode SD and the first switch 26, and the primary drive circuit PDC is formed by the fourth electrode 12 d functioning as the primary drive electrode PD and the fourth switch 29. In the following description, the state of FIG. 1 is defined as the state before the electrical inversion control, and the state of FIG. 4 is defined as the state after the electrical inversion control.

[0038] (Detection of angular velocity based on difference in output signal to secondary drive electrode before and after electrical inversion control) As shown in Figures 1 and 4, the control unit 20 performs control to detect angular velocity based on difference in output signal to secondary drive electrode SD before and after electrical inversion control.

[0039] 1, the control unit 20 acquires an output signal to the fourth electrode 12d (functioning as the secondary drive electrode SD) in a state (a state before the electrical inversion control) in which the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d are connected to the primary AC power supply 21, the primary detection unit 22, the secondary detection unit 23, and the secondary AC power supply 24, respectively. Also, as shown in FIG. 4, the control unit 20 acquires an output signal to the first electrode 12a (functioning as the secondary drive electrode SD) in a state (a state after the electrical inversion control) in which the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d are connected to the secondary AC power supply 24, the secondary detection unit 23, the primary detection unit 22, and the primary AC power supply 21, respectively. Then, the control unit 20 detects the angular velocity of the vibrator 11 based on the difference between the output signal to the fourth electrode 12d (functioning as the secondary drive electrode SD) in the state before the electrical inversion control (the state in Figure 1) and the output signal to the first electrode 12a (functioning as the secondary drive electrode SD) in the state after the electrical inversion control (the state in Figure 4).

[0040] 5, the control unit 20 is configured to perform control for switching between an inversion mode in which the angular velocity is detected based on the difference between the output signals to the secondary drive electrodes SD before and after electrical inversion control, and a non-inversion mode in which the angular velocity is detected based on the output signals to the secondary drive electrodes SD without performing electrical inversion control. Note that in the non-inversion mode, the state (the state in FIG. 1) in which the first electrode 12 a, the second electrode 12 b, the third electrode 12 c, and the fourth electrode 12 d function as the primary drive electrode PD, the primary detection electrode PPO, the secondary detection electrode SPO, and the secondary drive electrode SD, respectively, continues. In addition, in the inversion mode, a state in which the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d function as the primary drive electrode PD, the primary detection electrode PPO, the secondary detection electrode SPO, and the secondary drive electrode SD, respectively (the state in Figure 1), and a state in which the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d function as the secondary drive electrode SD, the secondary detection electrode SPO, the primary detection electrode PPO, and the primary drive electrode PD, respectively (the state in Figure 4) are repeatedly alternated.

[0041] In the inversion mode, the control unit 20 detects the angular velocity based on the difference between the output signals to the secondary drive electrodes SD before and after the electrical inversion control. Therefore, since a period of time during which the angular velocity cannot be detected occurs due to the switching of electrodes by the electrical inversion control, measurement cannot be performed in a motion state in which the angular velocity applied to the vibrator 11 fluctuates greatly (i.e., the angular velocity detection range is relatively small (e.g., approximately ±50 deg / sec)). However, the angular velocity detection accuracy is relatively high. Therefore, the inversion mode is used for applications in which the azimuth angle of an article on which the gyroscope 100 is mounted is detected based on the detected angular velocity of the Earth's rotation. On the other hand, in the non-inversion mode, as described below, although the angular velocity detection accuracy is relatively low, no period of time during which the angular velocity cannot be detected occurs, and therefore the angular velocity detection range is relatively wide (e.g., approximately ±200 to ±400 deg / sec). In other words, the non-inversion mode is suitable for measurement in a motion state in which the angular velocity applied to the vibrator 11 fluctuates greatly. Therefore, the non-inversion mode is used for applications in which an attitude angle is detected based on an angular velocity that accompanies a change in the attitude of an article that is equipped with the gyroscope 100. That is, one gyroscope 100 is used for two applications: detecting the azimuth angle of an article that is equipped with the gyroscope 100 based on the detected angular velocity of the Earth's rotation, and detecting the attitude angle based on the detected angular velocity that accompanies a change in the attitude of an article that is equipped with the gyroscope 100.

[0042] In the non-reversal mode, as described above, the angular velocity detection accuracy is relatively low, but the angular velocity detection range must be relatively large. In this case, the current range for driving the secondary drive electrodes SD must be relatively large. Therefore, the secondary drive circuit SDC in the non-reversal mode is provided with a range switching element 32a for switching the current range for driving the secondary drive electrodes SD. In the gyroscope 100, the circuit symmetry element 31a (described later) is not electrically controlled, and the range switching element 32a switches the current range in response to switching between the reversal mode and the non-reversal mode. This drives the secondary drive electrodes SD before and after electrical reversal control in a first current range in the reversal mode, and drives the secondary drive electrodes SD in a second current range larger than the first current range in the non-reversal mode. Note that the gyroscope 100 is an inductive gyroscope.

[0043] (Configuration of Range Switching Element) As shown in FIG. 6 , the secondary drive circuit SDC in the non-inverting mode includes a secondary amplifier SA that outputs a current for driving the secondary drive electrode SD. The range switching element 32a is a switch that bypasses the resistor SR provided on the input side of the secondary amplifier SA in the non-inverting mode. The secondary amplifier SA is an amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal. That is, in the secondary drive circuit SDC in the non-inverting mode, an inverting amplifier circuit is formed on the input side of the secondary drive electrode SD. Note that in the non-inverting mode, the first electrode 12a and the fourth electrode 12d function as the primary drive electrode PD and the secondary drive electrode SD, respectively. Also, in the non-inverting mode, the amplifier 32b and the resistor 32c function as the secondary amplifier SA and the resistor SR, respectively. Note that FIG. 6 shows the primary drive circuit PDC and the secondary drive circuit SDC in the non-inverting mode.

[0044] As shown in FIGS. 6 and 7 , the range-switching element 32a is configured to change the gain of the amplifier 32b (secondary amplifier SA) by switching between an OFF state and an ON state. Specifically, as shown in FIG. 7 , when the range-switching element 32a is turned ON, both ends of the resistor 32c (resistor SR) are shorted, thereby reducing the combined resistance value on the input side of the inverting input terminal. Since the gain of the amplifier 32b (secondary amplifier SA) is inversely proportional to the combined resistance value on the input side of the inverting input terminal, turning ON the range-switching element 32a increases the gain of the amplifier 32b (secondary amplifier SA). Note that FIG. 7 shows the primary drive circuit PDC and the secondary drive circuit SDC in the state before electrical inversion control is performed in the inversion mode (the state shown in FIG. 1 ).

[0045] As shown in FIG. 6 , the gyroscope 100 includes a range switching switch power supply 32d connected to a switch serving as the range switching element 32a. The gyroscope 100 also includes a range switching switch control unit 32e for switching the switch serving as the range switching element 32a between an OFF state and an ON state. As shown in FIGS. 6 and 7 , the range switching switch control unit 32e switches the switch serving as the range switching element 32a between an OFF state and an ON state, thereby changing the gain of the amplifier 32b (secondary amplifier SA). When the switch serving as the range switching element 32a is in the ON state shown in FIG. 6 , the gain of the amplifier 32b (secondary amplifier SA) is greater than when the switch serving as the range switching element 32a is in the OFF state shown in FIG. 7 , and therefore the current range for driving the fourth electrode 12d (secondary drive electrode SD) is increased accordingly. The range switching switch control unit 32e is configured to use the switch as the range switching element 32a in the ON state in the non-inversion mode, thereby increasing the amplification factor of the amplifier 32b (secondary amplifier SA) compared to when the switch as the range switching element 32a is in the OFF state.

[0046] (Configuration of Circuit Symmetry Element) As shown in Figures 6 to 8, the primary drive circuit PDC (see Figure 6) in the non-inverting mode is provided with a circuit symmetry element 31a to achieve symmetry between the secondary drive circuit SDC (see Figures 7 and 8) before and after electrical inversion control in the inverting mode. The circuit symmetry element 31a is provided at a position corresponding to the range switching element 32a and has the same structure as the range switching element 32a. Note that Figure 8 shows the primary drive circuit PDC and secondary drive circuit SDC in the state after electrical inversion control has been performed in the inverting mode (the state shown in Figure 4).

[0047] Specifically, as shown in FIG. 6 , the primary drive circuit PDC in the non-inverting mode includes a primary amplifier PA that outputs a current for driving the primary drive electrode PD. The circuit symmetry element 31a is a switch that bypasses the resistor PR provided on the input side of the primary amplifier PA in the non-inverting mode and is positioned corresponding to the switch serving as the range switching element 32a. The primary amplifier PA is an amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal. That is, in the primary drive circuit PDC in the non-inverting mode, an inverting amplifier circuit is formed on the input side of the primary drive electrode PD. In the non-inverting mode, the amplifier 31b and the resistor 31c function as the primary amplifier PA and the resistor PR, respectively.

[0048] The switch serving as the circuit symmetry element 31a has the same structure as the switch serving as the range switching element 32a, and is from the same production lot as the switch serving as the range switching element 32a.

[0049] As shown in Figures 7 and 8, in the inversion mode, the functions of the secondary amplifier SA and the primary amplifier PA are switched before and after electrical inversion control. Specifically, as shown in Figure 7, when the first electrode 12a and the fourth electrode 12d function as the primary drive electrode PD and the secondary drive electrode SD, respectively, the amplifiers 31b and 32b function as the primary amplifier PA and the secondary amplifier SA, respectively. Also, as shown in Figure 8, when the fourth electrode 12d and the first electrode 12a function as the primary drive electrode PD and the secondary drive electrode SD, respectively, the amplifiers 32b and 31b function as the primary amplifier PA and the secondary amplifier SA, respectively. Note that, as shown in Figures 7 and 8, the switch serving as the range switching element 32a is always kept in the OFF state in the inversion mode, thereby ensuring that the amplification factors of the secondary amplifier SA and the primary amplifier PA are equal.

[0050] The gyroscope 100 includes a circuit symmetry switch power supply 31d connected to the switch serving as the circuit symmetry element 31a. The gyroscope 100 does not include a switch control unit for switching the switch serving as the circuit symmetry element 31a between an OFF state and an ON state. As shown in FIGS. 6 to 8 , the switch serving as the circuit symmetry element 31a is not electrically controlled and is configured to be always used in the OFF state (i.e., in both the inverting mode and the non-inverting mode) so that the amplification factors of the secondary amplifier SA and the primary amplifier PA are equal. In other words, the switch serving as the circuit symmetry element 31a exists in the circuit (the primary drive circuit PDC in the non-inverting mode, and the primary drive circuit PDC and the secondary drive circuit SDC in the inverting mode) without functioning as an electrical component. As shown in Figures 7 and 8, the switch serving as the range switching element 32a and the switch serving as the circuit symmetry element 31a are always used in the OFF state in the inversion mode, so that the resistors 32c and 31c are not bypassed, and the gains of the amplifiers 32b and 31b are equal. This allows the function as the primary drive circuit PDC and the function as the secondary drive circuit SDC to be alternated by electrical inversion control in the inversion mode. This allows both the circuit provided with the switch serving as the range switching element 32a and the circuit provided with the switch serving as the circuit symmetry element 31a to be used as the secondary drive circuit SDC before and after electrical inversion control.

[0051] (Effects of First Embodiment) In the first embodiment, the following effects can be obtained.

[0052] In the first embodiment, as described above, the secondary drive circuit SDC in the non-inverting mode is provided with a range switching element 32a for switching the current range for driving the secondary drive electrodes SD. The primary drive circuit PDC in the non-inverting mode is provided with a circuit symmetry element 31a for achieving symmetry between the secondary drive circuit SDC before and after electrical inversion control in the inverting mode. The circuit symmetry element 31a is provided at a position corresponding to the range switching element 32a and has the same structure as the range switching element 32a. This prevents the symmetry between the secondary drive circuit SDC before and after electrical inversion control in the inverting mode from being reduced (i.e., the stray capacitance between the secondary drive circuit SDC before and after electrical inversion control in the inverting mode is different) compared to when the primary drive circuit PDC in the non-inverting mode does not have the circuit symmetry element 31a. Furthermore, since the circuit symmetry element 31a is provided at a position corresponding to the range switching element 32a and has the same structure as the range switching element 32a, the characteristics (stray capacitance) of the circuit symmetry element 31a become similar to those of the range switching element 32a, reliably preventing the symmetry of the secondary drive circuit SDC before and after the electrical inversion control in the inversion mode from becoming low (i.e., the stray capacitance of the secondary drive circuit SDC before and after the electrical inversion control in the inversion mode is different). This prevents a difference in the bias component of the output signal to the secondary drive electrode SD before and after the electrical inversion control in the inversion mode. As a result, in a configuration in which the range switching element 32a is provided in the secondary drive circuit SDC in the non-inversion mode, where switching is performed between an inversion mode in which electrical inversion control is performed and a non-inversion mode in which electrical inversion control is not performed, it is possible to prevent the bias component from being unable to be properly canceled by differentiating the output signal to the secondary drive electrode SD before and after the electrical inversion control in the inversion mode.

[0053] In the first embodiment, as described above, the secondary drive circuit SDC in the non-inverting mode includes a secondary amplifier SA that outputs a current for driving the secondary drive electrodes SD. The primary drive circuit PDC in the non-inverting mode includes a primary amplifier PA that outputs a current for driving the primary drive electrodes PD. In the inverting mode, the secondary amplifier SA and the primary amplifier PA are configured to switch their functions before and after electrical inversion control. The range switching element 32a is a switch that bypasses the resistor SR provided on the input side of the secondary amplifier SA in the non-inverting mode. The circuit symmetry element 31a is a switch that bypasses the resistor PR provided on the input side of the primary amplifier PA in the non-inverting mode and is located at a position corresponding to the switch serving as the range switching element 32a. The switch serving as the circuit symmetry element 31a has the same structure as the switch serving as the range switching element 32a. This makes it possible to easily realize a configuration in which the circuit symmetry element 31a is provided at a position corresponding to the range switching element 32a and is an element having the same structure as the range switching element 32a.

[0054] Furthermore, in the first embodiment, as described above, the gyroscope 100 includes the range switching switch power supply 32d connected to the switch serving as the range switching element 32a, and the circuit symmetry switch power supply 31d connected to the switch serving as the circuit symmetry element 31a. This makes it possible to further prevent the symmetry of the secondary drive circuit SDC from decreasing before and after electrical inversion control in the inversion mode, compared to a case in which the gyroscope 100 does not include the circuit symmetry switch power supply 31d connected to the switch serving as the circuit symmetry element 31a.

[0055] Furthermore, in the first embodiment, as described above, the gyroscope 100 includes a range switching switch control unit 32e for switching the switch serving as the range switching element 32a between an OFF state and an ON state. The range switching switch control unit 32e is configured to use the switch serving as the range switching element 32a in an ON state in the non-inverting mode to increase the amplification factor of the secondary amplifier SA compared to when the switch serving as the range switching element 32a is in an OFF state, and to use the switch serving as the range switching element 32a in an OFF state in the inverting mode to equalize the amplification factors of the secondary amplifier SA and the primary amplifier PA. The switch serving as the circuit symmetry element 31a is always used only in an OFF state, so that the amplification factors of the secondary amplifier SA and the primary amplifier PA are equalized. This eliminates the need for a switch control unit for switching the switch serving as the circuit symmetry element 31a between an OFF state and an ON state, thereby reducing the number of components and simplifying the circuit configuration.

[0056] Furthermore, in the first embodiment, as described above, the switch serving as the circuit symmetry element 31a is a switch from the same production lot as the switch serving as the range switching element 32a. This allows the characteristics (stray capacitance) of the switch serving as the circuit symmetry element 31a to be closer to the characteristics of the switch serving as the range switching element 32a, compared to when the switch serving as the circuit symmetry element 31a is not from the same production lot as the switch serving as the range switching element 32a. This further reduces the symmetry of the secondary drive circuit SDC before and after electrical reversal control in the reversal mode, compared to when the switch serving as the circuit symmetry element 31a is not from the same production lot as the switch serving as the range switching element 32a.

[0057] Furthermore, in the first embodiment, as described above, gyroscope 100 is configured such that circuit symmetry element 31 a is not electrically controlled, and the current range is switched by range switching element 32 a in conjunction with switching between the inversion mode and the non-inversion mode, so that secondary drive electrode SD is driven in a first current range before and after electrical inversion control in the inversion mode, and secondary drive electrode SD is driven in a second current range larger than the first current range in the non-inversion mode. This makes it possible to make the output signal to secondary drive electrode SD before and after electrical inversion control relatively small in the inversion mode, and to make the output signal to secondary drive electrode SD relatively large in the non-inversion mode. As a result, in the inversion mode, although the detection range of the angular velocity based on the output signal to the secondary drive electrode SD before and after the electrical inversion control is relatively small, the detection accuracy of the angular velocity based on the output signal to the secondary drive electrode SD before and after the electrical inversion control is relatively high, and in the non-inversion mode, although the detection accuracy of the angular velocity based on the output signal to the secondary drive electrode SD is relatively low, a configuration can be reliably realized in which the detection range of the angular velocity based on the output signal to the secondary drive electrode SD is relatively large.

[0058] 9 to 13, the configuration of a gyroscope 200 according to a second embodiment of the present invention will be described. In the drawings, the same components as those in the gyroscope 100 according to the first embodiment are denoted by the same reference numerals.

[0059] (Overall Configuration of Gyroscope) As shown in FIG. 9 , the gyroscope 200 includes a control unit 220 .

[0060] (Electrical Inversion Control) As shown in Figures 9 and 10, the control unit 220 is configured to perform electrical inversion control to exchange the functions of the primary drive circuit PDC2 and the secondary drive circuit SDC2, and to exchange the functions of the primary detection electrode PPO and the secondary detection electrode SPO.

[0061] 9 , a primary control circuit PC2 is configured by the first electrode 12 a functioning as the primary drive electrode PD, the second electrode 12 b functioning as the primary detection electrode PPO, the primary AC power supply 21, and the primary detection unit 22, and a secondary control circuit SC2 is configured by the third electrode 12 c functioning as the secondary detection electrode SPO, the fourth electrode 12 d functioning as the secondary drive electrode SD, the secondary detection unit 23, and the secondary AC power supply 24. Note that, in the state of Fig. 9 , a primary drive circuit PDC2 is configured by the first electrode 12 a functioning as the primary drive electrode PD and the first switch 26, and a secondary drive circuit SDC2 is configured by the fourth electrode 12 d functioning as the secondary drive electrode SD and the fourth switch 29.

[0062] 10 , a primary control circuit PC2 is configured by the fourth electrode 12 d functioning as the primary drive electrode PD, the third electrode 12 c functioning as the primary detection electrode PPO, the primary AC power supply 21, and the primary detection unit 22, and a secondary control circuit SC2 is configured by the second electrode 12 b functioning as the secondary detection electrode SPO, the first electrode 12 a functioning as the secondary drive electrode SD, the secondary detection unit 23, and the secondary AC power supply 24. Note that, in the state of Fig. 10 , a secondary drive circuit SDC2 is configured by the first electrode 12 a functioning as the secondary drive electrode SD and the first switch 26, and a primary drive circuit PDC2 is configured by the fourth electrode 12 d functioning as the primary drive electrode PD and the fourth switch 29.

[0063] (Configuration of Range Switching Element) As shown in FIG. 11 , the secondary drive circuit SDC2 in the non-inverting mode includes a secondary amplifier SA that outputs a current for driving the secondary drive electrode SD. Between the range switching element 232a and the secondary amplifier SA, multiple (two) secondary branch circuits 232f are provided, each of which is a parallel circuit including resistors 232c with different resistance values. Specifically, between the range switching element 232a and the secondary amplifier SA, a secondary branch circuit 232fa including a resistor 232ca having a first resistance value and a secondary branch circuit 232fb including a resistor 232cb having a second resistance value smaller than the first resistance value are provided in parallel. Note that FIG. 11 shows the primary drive circuit PDC2 and the secondary drive circuit SDC2 in the non-inverting mode.

[0064] 11 and 12, the range switching element 232a is a switch configured to switch the secondary branch circuit 232f to which the secondary AC power supply 24 is connected, among the multiple secondary branch circuits 232f. As shown in Fig. 11, when the secondary AC power supply 24 is connected to the secondary branch circuit 232fb including the resistor 232cb having the second resistance value, the combined resistance value on the input side of the inverting input terminal of the amplifier 32b (secondary amplifier SA) becomes relatively small, resulting in a relatively large gain of the amplifier 32b (secondary amplifier SA). As shown in Fig. 12, when the secondary AC power supply 24 is connected to the secondary branch circuit 232fa including the resistor 232ca having the first resistance value, the combined resistance value on the input side of the inverting input terminal of the amplifier 32b (secondary amplifier SA) becomes relatively large, resulting in a relatively small gain of the amplifier 32b (secondary amplifier SA). 12 shows the primary drive circuit PDC2 and the secondary drive circuit SDC2 in the state before electrical inversion control is performed in the inversion mode (the state shown in FIG. 9).

[0065] 11 and 12 , the gyroscope 200 includes a range switching switch control unit 232e that controls a switch serving as a range switching element 232a to switch the secondary-side branch circuit unit 232f to which the secondary AC power supply 24 is connected. The range switching switch control unit 232e is configured to increase the amplification factor of the secondary amplifier SA in the non-inverting mode by connecting the secondary AC power supply 24 to the secondary-side branch circuit unit 232fb including the smallest resistance 232cb compared to a state in which the secondary AC power supply 24 is connected to the secondary-side branch circuit unit 232fa including the other resistance 232ca.

[0066] As shown in FIG. 11, the gyroscope 200 includes a range switching switch power supply 232d connected to a switch serving as a range switching element 232a.

[0067] (Configuration of Circuit Symmetry Element) As shown in Figures 11 to 13, the primary drive circuit PDC2 (see Figure 11) in the non-inverting mode is provided with a circuit symmetry element 231a to achieve symmetry between the secondary drive circuit SDC2 (see Figures 12 and 13) before and after electrical inversion control in the inverting mode. The circuit symmetry element 231a is provided at a position corresponding to the range switching element 232a and has the same structure as the range switching element 232a. Note that Figure 13 shows the primary drive circuit PDC2 and secondary drive circuit SDC2 in the state after electrical inversion control has been performed in the inverting mode (the state shown in Figure 10).

[0068] 11 , the primary drive circuit PDC2 in the non-inverting mode includes a primary amplifier PA that outputs a current for driving the primary drive electrodes PD. Between the circuit symmetry element 231a and the primary amplifier PA, multiple (two) primary-side branch circuits 231f are provided, each of which is a parallel circuit including resistors 231c with different resistance values. Specifically, between the circuit symmetry element 231a and the primary amplifier PA, a primary-side branch circuit 231fa including a resistor 231ca having a first resistance value and a primary-side branch circuit 231fb including a resistor 231cb having a second resistance value smaller than the first resistance value are provided in parallel. Here, the resistor 231ca of the primary-side branch circuit 231fa and the resistor 232ca of the secondary-side branch circuit 232fa have the same resistance value, and the resistor 231cb of the primary-side branch circuit 231fb and the resistor 232cb of the secondary-side branch circuit 232fb have the same resistance value. That is, the resistors 232c of the multiple (two) secondary-side branch circuits 232f and the resistors 231c of the multiple (two) primary-side branch circuits 231f have the same resistance value. The multiple (two) secondary-side branch circuits 232f and the multiple (two) primary-side branch circuits 231f have the same structure. The switch serving as the circuit symmetry element 231a is located at a position corresponding to the switch serving as the range switching element 232a and has the same structure as the switch serving as the range switching element 232a.

[0069] 12 and 13, in the inversion mode, the functions of the secondary amplifier SA and the primary amplifier PA are switched before and after the electrical inversion control. Specifically, as shown in FIG. 12, when the first electrode 12a and the fourth electrode 12d function as the primary drive electrode PD and the secondary drive electrode SD, respectively, the amplifier 31b and the amplifier 32b function as the primary amplifier PA and the secondary amplifier SA, respectively. Also, as shown in FIG. 13, when the fourth electrode 12d and the first electrode 12a function as the primary drive electrode PD and the secondary drive electrode SD, respectively, the amplifier 32b and the amplifier 31b function as the primary amplifier PA and the secondary amplifier SA, respectively.

[0070] Specifically, the range switching switch control unit 232e is configured to control the switch serving as the range switching element 232a to connect the secondary AC power supply 24 to the secondary-side branch circuit 232fa including the largest resistance 232ca in the inverting mode, thereby equalizing the gains of the secondary amplifier SA and the primary amplifier PA. The switch serving as the circuit symmetry element 231a is configured to always connect the primary AC power supply 21 to the primary-side branch circuit 231fa including the largest resistance 231ca, thereby equalizing the gains of the secondary amplifier SA and the primary amplifier PA. In other words, the circuit symmetry element 231a is a switch configured not to switch the primary-side branch circuit 231f to which the primary AC power supply 21 is connected, among the multiple primary-side branch circuits 231f.

[0071] The gyroscope 200 includes a circuit symmetry switch power supply 231d connected to a switch serving as a circuit symmetry element 231a. The gyroscope 200 does not include a circuit symmetry switch control unit that controls the switch serving as the circuit symmetry element 231a to switch the primary-side branch circuit unit 231fa to which the primary AC power supply 21 is connected.

[0072] The other configurations of the gyroscope 200 of the second embodiment are similar to those of the gyroscope 100 of the first embodiment.

[0073] (Effects of Second Embodiment) In the second embodiment, the following effects can be obtained.

[0074] In the second embodiment, as described above, the gyroscope 200 includes a secondary AC power supply 24 that supplies AC current as an output signal to the secondary drive electrodes SD to cancel secondary vibrations, and a primary AC power supply 21 that supplies AC current to the primary drive electrodes PD. In the non-inverting mode, the secondary drive circuit SDC2 includes a secondary amplifier SA that outputs a current for driving the secondary drive electrodes SD. In the non-inverting mode, the primary drive circuit PDC2 includes a primary amplifier PA that outputs a current for driving the primary drive electrodes PD. In the inverting mode, the functions of the secondary amplifier SA and the primary amplifier PA are switched before and after electrical inversion control. Between the range switching element 232a and the secondary amplifier SA, multiple secondary-side branch circuits 232f are provided, each of which is a parallel circuit including resistors 232c with different resistance values. Between the circuit symmetry element 231a and the primary amplifier PA, multiple primary-side branch circuits 231f are provided, each of which is a parallel circuit including resistors 231c with different resistance values. The multiple secondary branch circuits 232f and the multiple primary branch circuits 231f have the same structure. The resistors 232c of the multiple secondary branch circuits 232f and the resistors 231c of the multiple primary branch circuits 231f have the same resistance value. The range switching element 232a is a switch configured to switch the secondary branch circuit 232f to which the secondary AC power supply 24 is connected among the multiple secondary branch circuits 232f. The circuit symmetry element 231a is a switch configured not to switch the primary branch circuit 231f to which the primary AC power supply 21 is connected among the multiple primary branch circuits 231f. The switch serving as the circuit symmetry element 231a is located at a position corresponding to the switch serving as the range switching element 232a and has the same structure as the switch serving as the range switching element 232a. As a result, stray capacitance exists in the primary side branch circuit section 231f that is not connected to the primary AC power supply 21, and parasitic capacitance exists in the primary side branch circuit section 231f that is connected to the primary AC power supply 21.Furthermore, stray capacitance exists in the secondary-side branch circuit 232f that is not connected to the secondary AC power supply 24, and parasitic capacitance exists in the secondary-side branch circuit 232f that is connected to the secondary AC power supply 24. Because the secondary AC power supply 24 is connected to one of the multiple secondary-side branch circuits 232f, stray capacitance or parasitic capacitance exists in all secondary-side branch circuits 232f regardless of which secondary-side branch circuit 232f the secondary AC power supply 24 is connected to. This makes it possible to equalize the influence of the stray capacitance and parasitic capacitance existing in the secondary-side branch circuit 232f and the influence of the stray capacitance and parasitic capacitance existing in the primary-side branch circuit 231f. As a result, it is possible to prevent the symmetry of the secondary drive circuit SDC2 before and after electrical inversion control in the inversion mode from decreasing immediately after switching the angular velocity detection range and switching from the non-inversion mode to the inversion mode.

[0075] Furthermore, in the second embodiment, as described above, the gyroscope 200 includes a range switching switch control unit 232e that controls a switch serving as the range switching element 232a to switch the secondary-side branch circuit unit 232f to which the secondary AC power supply 24 is connected. Furthermore, the range switching switch control unit 232e is configured to increase the amplification factor of the secondary amplifier SA in the non-inverting mode by connecting the secondary AC power supply 24 to the secondary-side branch circuit unit 232fb including the smallest resistance 232cb compared to a state in which the secondary AC power supply 24 is connected to a secondary-side branch circuit unit 232f including another resistance 232c. Furthermore, range switching switch control section 232e is configured to equalize the gains of secondary amplifier SA and primary amplifier PA by controlling range switching element 232a to connect secondary AC power supply 24 to secondary-side branch circuit section 232fa including largest resistor 232ca in the inverting mode, and circuit symmetry element 231a to maintain primary AC power supply 21 always connected to primary-side branch circuit section 231fa including largest resistor 231ca in the inverting mode, thereby equalizing the gains of secondary amplifier SA and primary amplifier PA. This allows secondary drive electrode SD to be driven in a relatively small current range in the inverting mode, and allows secondary drive electrode SD to be driven in a relatively large current range in the non-inverting mode. This allows the output signal to secondary drive electrode SD before and after electrical inversion control to be relatively small in the inverting mode, and relatively large in the non-inverting mode. As a result, in the inversion mode, although the detection range of the angular velocity based on the output signal to the secondary drive electrode SD before and after the electrical inversion control is relatively small, the detection accuracy of the angular velocity based on the output signal to the secondary drive electrode SD before and after the electrical inversion control is relatively high, and in the non-inversion mode, although the detection accuracy of the angular velocity based on the output signal to the secondary drive electrode SD is relatively low, a configuration can be reliably realized in which the detection range of the angular velocity based on the output signal to the secondary drive electrode SD is relatively large.

[0076] (Modifications) The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and includes all modifications (modifications) within the meaning and scope of the claims.

[0077] For example, in the first and second embodiments, the switch serving as the circuit symmetry element 31a (231a) is a switch from the same production lot as the switch serving as the range switching element 32a (232a), but the present invention is not limited to this. In the present invention, the switch serving as the circuit symmetry element does not have to be a switch from the same production lot as the switch serving as the range switching element. In this case, it is desirable to measure the characteristics (parasitic capacitance) of the switch serving as the circuit symmetry element and the switch serving as the range switching element so that the switch serving as the circuit symmetry element has the same characteristics (stray capacitance) as the switch serving as the range switching element, and select a switch serving as the circuit symmetry element that has approximately the same characteristics (parasitic capacitance) as the switch serving as the range switching element.

[0078] In the first and second embodiments, the gyroscope 100 (200) does not include a circuit symmetry switch control unit for switching the switch serving as the circuit symmetry element 31 a (231 a) between the OFF state and the ON state, but the present invention is not limited to this. In the present invention, the gyroscope may include a circuit symmetry switch control unit for switching the switch serving as the circuit symmetry element between the OFF state and the ON state.

[0079] In the first and second embodiments, the gyroscope 100 (200) includes the power supply for circuit symmetry switch 31d (231d) connected to the switch serving as the element for circuit symmetry 31a (231a), but the present invention is not limited to this. In the present invention, the gyroscope does not need to include the power supply for circuit symmetry switch connected to the switch serving as the element for circuit symmetry.

[0080] In the first embodiment described above, the secondary drive circuit SDC is provided with a secondary amplifier SA that outputs a current for driving the secondary drive electrode SD, and the primary drive circuit PDC is provided with a primary amplifier PA that outputs a current for driving the primary drive electrode PD. In the inversion mode, the secondary amplifier SA and the primary amplifier PA are configured to switch their functions before and after electrical inversion control. The range switching element 32a is a switch that is provided to bypass a resistor SR that is provided on the input side of the secondary amplifier SA in the non-inversion mode. The circuit symmetry element 31a is a switch that is provided at a position corresponding to the switch serving as the range switching element 32a and that bypasses a resistor PR that is provided on the input side of the primary amplifier PA in the non-inversion mode. Although an example has been shown in which the switch serving as the circuit symmetry element 31a has the same structure as the switch serving as the range switching element 32a, the present invention is not limited to this. In the present invention, one of the range switching element and the circuit symmetry element may be an element other than the switch (for example, a variable resistor), or both the range switching element and the circuit symmetry element may be elements other than the switch. Also, an electronic component other than a switch (for example, a resistor) serving as a range switching element may be provided in a path bypassing a resistor provided on the input side of the secondary amplifier in the non-inverting mode, and an electronic component having the same structure as the electronic component other than a switch serving as a range switching element may be provided in a position corresponding to the electronic component other than a switch serving as a range switching element in a path bypassing a resistor provided on the input side of the primary amplifier in the non-inverting mode.

[0081] In the second embodiment, two secondary-side branch circuits 232f, which are parallel circuits including resistors 232c with different resistance values, are provided between the range-switching element 232a and the secondary amplifier SA, and two primary-side branch circuits 231f, which are parallel circuits including resistors 231c with different resistance values, are provided between the circuit symmetry element 231a and the primary amplifier PA. However, the present invention is not limited to this. In the present invention, three or more secondary-side branch circuits, which are parallel circuits including resistors with different resistance values, may be provided between the range-switching element and the secondary amplifier, and three or more primary-side branch circuits, which are parallel circuits including resistors with different resistance values, may be provided between the circuit symmetry element and the primary amplifier.

[0082] In the first and second embodiments, the vibrator 11 is formed in a ring shape having a rotationally symmetrical shape, but the present invention is not limited to this. In the present invention, the vibrator may be formed in a flat plate shape having a rotationally symmetrical shape.

[0083] In the first and second embodiments, the gyroscope 100 (200) is an inductive gyroscope, and the secondary drive circuit SDC (SDC2) in the non-inverting mode is provided with a range switching element 32a (232a) for switching the current range for driving the secondary drive electrodes SD, and the primary drive circuit PDC (PDC2) in the non-inverting mode is provided with a circuit symmetry element 31a (231a) (corresponding to the range switching element 32a (232a) for switching the current range for driving the secondary drive electrodes SD, which is provided in the secondary drive circuit SDC (SDC2) in the non-inverting mode) for obtaining symmetry of the secondary drive circuit SDC (SDC2) before and after the electrical inversion control in the inverting mode. In the example shown, the secondary drive circuit SDC (SDC2) is provided with a secondary amplifier SA that outputs a current for driving the secondary drive electrode SD, and the primary drive circuit PDC (PDC2) in the non-inverting mode is provided with a primary amplifier PA that outputs a current for driving the primary drive electrode PD, and the circuit symmetry element 31 a (231 a) is not electrically controlled, and the current range is switched by the range switching element 32 a (232 a) in conjunction with switching between the inverting mode and the non-inverting mode, so that in the inverting mode, the secondary drive electrode SD is driven in a first current range before and after electrical inversion control, and in the non-inverting mode, the secondary drive electrode SD is driven in a second current range that is larger than the first current range, but the present invention is not limited to this.In the present invention, when the gyroscope is a capacitive or piezoelectric gyroscope, the secondary drive circuit in the non-inverting mode is provided with a range switching element for switching the voltage range for driving the secondary drive electrodes, and the primary drive circuit in the non-inverting mode is provided with a circuit symmetry element (corresponding to the range switching element for switching the voltage range for driving the secondary drive electrodes, provided in the secondary drive circuit in the non-inverting mode) for obtaining symmetry of the secondary drive circuit before and after electrical inversion control in the inverting mode, and the secondary drive circuit in the non-inverting mode is provided with a secondary amplifier that outputs a voltage for driving the secondary drive electrode, and the primary drive circuit in the non-inverting mode is provided with a primary amplifier that outputs a voltage for driving the primary drive electrode, and the circuit symmetry element is not electrically controlled, and the voltage range is switched by the range switching element in conjunction with switching between the inverting mode and the non-inverting mode, so that in the inverting mode, the secondary drive electrode before and after the electrical inversion control is driven in a first voltage range, and in the non-inverting mode, the secondary drive electrode is driven in a second voltage range that is larger than the first voltage range.

[0084] 10 Vibration type gyro element 11 Vibrator 20, 220 Control unit 21 Primary AC power supply 24 Secondary AC power supply 31a, 231a Circuit symmetry element 31d, 231d Circuit symmetry switch power supply 32a, 232a Range switching element 32d, 232d Range switching switch power supply 32e, 232e Range switching switch control unit 100, 200 Gyroscope 231c Resistor (included in primary side branch circuit unit) 231ca (largest resistor included in primary side branch circuit unit) 231f Primary side branch circuit unit 231fa Primary side branch circuit unit (including largest resistor) 232f Secondary side branch circuit unit 232c Resistor (included in secondary side branch circuit unit) 232ca (largest resistor included in secondary side branch circuit unit) 232cb (Smallest resistance included in the secondary branch circuit section) 232fa Secondary branch circuit section (including the largest resistance) 232fb Secondary branch circuit section (including the smallest resistance) PA Primary amplifier PD Primary drive electrode PDC, PDC2 Primary drive circuit PPO Primary detection electrode PR Resistor (provided on the input side of the primary amplifier) ​​SA Secondary amplifier SD Secondary drive electrode SDC, SDC2 Secondary drive circuit SPO Secondary detection electrode SR Resistor (provided on the input side of the secondary amplifier)

Claims

1. A vibrating gyro element including a vibrator, a primary drive electrode that generates a primary vibration in the vibrator, a primary detection electrode that detects the primary vibration, a secondary detection electrode that detects a secondary vibration of the vibrator caused by an angular velocity applied to the vibrator, and a secondary drive electrode that drives the vibrator to cancel the secondary vibration; and a control unit that controls detection of the angular velocity based on an output signal to the secondary drive electrode, wherein the primary drive electrode constitutes a primary drive circuit, and the secondary drive electrode constitutes a secondary drive circuit, and the control unit performs electrical inversion control that exchanges the function of the primary drive circuit with the function of the secondary drive circuit and exchanges the function of the primary detection electrode with the function of the secondary detection electrode, and is configured to switch between an inversion mode that detects the angular velocity based on a difference in output signal to the secondary drive electrode before and after the electrical inversion control, and a non-inversion mode that does not perform the electrical inversion control and detects the angular velocity based on the output signal to the secondary drive electrode, a range switching element provided in the secondary drive circuit in the non-inverting mode for switching a current range or a voltage range for driving the secondary drive electrode; a circuit symmetry element provided in the primary drive circuit in the non-inverting mode for achieving symmetry of the secondary drive circuit before and after the electrical inversion control in the inverting mode; and the circuit symmetry element provided in a position corresponding to the range switching element and having the same structure as the range switching element.

2. The gyroscope of claim 1, wherein the secondary drive circuit in the non-inverting mode is provided with a secondary amplifier that outputs a current or voltage for driving the secondary drive electrode, the primary drive circuit in the non-inverting mode is provided with a primary amplifier that outputs a current or voltage for driving the primary drive electrode, the secondary amplifier and the primary amplifier are configured to switch their functions before and after the electrical inversion control in the inverting mode, the range switching element is a switch provided to bypass a resistor provided on the input side of the secondary amplifier in the non-inverting mode, the circuit symmetry element is a switch provided to bypass a resistor provided on the input side of the primary amplifier in the non-inverting mode and is provided in a position corresponding to the switch serving as the range switching element, and the switch serving as the circuit symmetry element has the same structure as the switch serving as the range switching element.

3. A power supply further comprising: a secondary AC power supply which supplies AC current as the output signal to the secondary drive electrode so as to cancel the secondary vibration; and a primary AC power supply which supplies AC current to the primary drive electrode; wherein the secondary drive circuit in the non-inverting mode is provided with a secondary amplifier which outputs a current or voltage for driving the secondary drive electrode; the primary drive circuit in the non-inverting mode is provided with a primary amplifier which outputs a current or voltage for driving the primary drive electrode; wherein the secondary amplifier and the primary amplifier are configured to switch functions before and after the electrical inversion control in the inverting mode; between the range switching element and the secondary amplifier, there are provided a plurality of secondary branch circuits which are parallel circuits including resistors with different resistance values; between the circuit symmetry element and the primary amplifier, there are provided a plurality of primary branch circuits which are parallel circuits including resistors with different resistance values; the plurality of secondary branch circuits and the plurality of primary branch circuits have the same structure; and the resistors of the plurality of secondary branch circuits and the resistors of the plurality of primary branch circuits have the same resistance value.

2. The gyroscope according to claim 1, wherein the range switching element is a switch configured to be able to switch one of the plurality of secondary branch circuit units to which the secondary AC power supply is connected, and the circuit symmetry element is a switch configured not to switch one of the plurality of primary branch circuit units to which the primary AC power supply is connected, and the switch serving as the circuit symmetry element is provided at a position corresponding to the switch serving as the range switching element and has the same structure as the switch serving as the range switching element.

4. The gyroscope according to claim 2 or 3, further comprising: a range switching switch power supply connected to the switch as the range switching element; and a circuit symmetry switch power supply connected to the switch as the circuit symmetry element.

5. The gyroscope according to claim 2, further comprising a range switching switch control section for switching the switch as the range switching element between an OFF state and an ON state, wherein the range switching switch control section is configured such that, in the non-inverting mode, by using the switch as the range switching element in an ON state, the amplification factor of the secondary amplifier is made larger than when the switch as the range switching element is in an OFF state, and in the inverting mode, by using the switch as the range switching element in an OFF state, the amplification factors of the secondary amplifier and the primary amplifier are made equal, and the switch as the circuit symmetry element is configured such that, by always being used only in an OFF state, the amplification factors of the secondary amplifier and the primary amplifier are made equal.

6. The gyroscope according to claim 3, further comprising a range switching switch control section that controls the switch as the range switching element to switch the secondary-side branch circuit section to which the secondary AC power supply is connected, wherein the range switching switch control section is configured to control the switch as the range switching element to connect the secondary AC power supply to the secondary-side branch circuit section having the smallest resistance in the non-inverting mode, thereby making the amplification factor of the secondary amplifier larger than that in a state in which the secondary AC power supply is connected to the secondary-side branch circuit section having another resistance, and to control the switch as the range switching element to connect the secondary AC power supply to the secondary-side branch circuit section having the largest resistance in the inverting mode, thereby making the amplification factors of the secondary amplifier and the primary amplifier equal, and wherein the switch as the circuit symmetry element is configured to be used only in a state in which the primary AC power supply is always connected to the primary-side branch circuit section having the largest resistance, thereby making the amplification factors of the secondary amplifier and the primary amplifier equal.

7. The gyroscope according to claim 2 or 3, wherein the switch as the circuit symmetry element is a switch from the same lot as the switch as the range switching element.

8. The gyroscope of claim 1, wherein the circuit symmetry element is not electrically controlled, and the current range or the voltage range is switched by the range switching element in conjunction with switching between the inverting mode and the non-inverting mode, so that in the inverting mode, the secondary drive electrode is driven in a first current range or a first voltage range before and after the electrical inversion control, and in the non-inverting mode, the secondary drive electrode is driven in a second current range greater than the first current range or a second voltage range greater than the first voltage range.

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