JP2019128327A - Physical quantity detection device - Google Patents

Abstract

To provide a physical quantity detection device capable of removing a disturbance signal.SOLUTION: A physical quantity detection device includes: first and second movable bodies which can vibrate in first and second directions; a first transducer which generates a first signal related to the position of the first movable body; a second transducer which generates a second signal related to the position of the second movable body; first and second amplifier circuits which amplify the first and second signals; a distribution control circuit for distributing the signal amplified by the second amplifier circuit to first and second distribution signals; a multiplication circuit which multiplies an output of the first amplifier circuit and the first distribution signals; a phase adjustment circuit which adjusts each of the phases of the second distribution signals; and a first actuator which adjusts the vibration of the second movable body on the basis of the phase-adjusted signals. The ratio of the second distribution signals to the first distribution signals is reduced with the lapse of time after the first movable body starts vibrating.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a physical quantity detection device.

  As a physical quantity detection device such as an angular velocity, a first vibration mechanism including a first movable body capable of vibrating in a first direction, and a first direction along with vibration of the first movable body in a first direction And a second vibration mechanism including a second movable body that vibrates and vibrates in a second direction perpendicular to the first direction.

  In order to detect an accurate physical quantity in the physical quantity detection apparatus described above, it is important to remove a disturbance signal. However, conventionally, it has not always been possible to effectively remove the disturbance signal.

Japanese Patent No. 4971490 U.S. Pat. No. 8,800,309 Japanese Patent No. 4370331

R. Gando et al., "An intermittent free-vibration MEMS gyroscope enabled by catch-and-release mechanism for low-power and fast-starting applications," Proc. Of MEMS, 2017, pp. 29-32.

  A physical quantity detection device capable of effectively removing a disturbance signal is provided.

  The physical quantity detection device according to the embodiment includes a first vibration mechanism including a first movable body that can vibrate in a first direction, and the first movable body according to the vibration of the first movable body in the first direction. A second vibration mechanism including a second movable body that vibrates in a first direction and capable of vibrating in a second direction perpendicular to the first direction; and based on vibration of the first movable body. A first transducer that generates a first signal related to the position of the first movable body, and a second signal that generates a second signal related to the position of the second movable body based on the vibration of the second movable body A first amplifying circuit that amplifies the first signal, a second amplifying circuit that amplifies the second signal, and a signal that is amplified by the second amplifying circuit. A distribution control circuit for distributing the signal to the second distribution signal; Note: A multiplication circuit that multiplies the output of the first amplification circuit by the first distribution signal, a phase adjustment circuit that adjusts the phase of the second distribution signal, and a signal adjusted by the phase adjustment circuit A first actuator for adjusting the vibration of the second movable body, and a ratio of the second distribution signal to the first distribution signal is determined after the first movable body starts to vibrate Decreases over time.

It is the figure which showed the basic concept of the physical quantity detection apparatus which concerns on embodiment. It is the block diagram which showed the specific structural example of the physical quantity detection apparatus which concerns on embodiment. FIG. 5 is a timing chart showing the operation of the physical quantity detection device according to the embodiment. FIG. 3 is an electric circuit diagram illustrating a first configuration example of a part of the physical quantity detection device illustrated in FIG. 2. FIG. 3 is an electric circuit diagram illustrating a second configuration example of a part of the physical quantity detection device illustrated in FIG. 2. It is an electric circuit diagram showing a detailed configuration of a switching control circuit included in the physical quantity detection device according to the embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a basic concept of a physical quantity detection device according to an embodiment. In FIG. 1, an angular velocity detection device based on Coriolis force will be described as a physical quantity detection device.

  The angular velocity detection device shown in FIG. 1 includes a drive system 11, a detection system 12, a drive system transducer 13 and a detection system transducer 14.

  The drive system 11 includes a movable body that can vibrate in the x direction (first direction), a drive mechanism that vibrates the movable body, and the like. The detection system 12 is configured of a movable body that can vibrate in the y direction (second direction), a detection mechanism, and the like. The movable body included in the detection system 12 is changed to a movable body included in the drive system 11 so that the movable body included in the detection system 12 vibrates in the x direction along with the vibration of the movable body included in the drive system 11. Mechanically coupled. Hereinafter, for convenience, the movable body included in the drive system 11 is referred to as a movable body 11m, and the movable body included in the detection system 12 is referred to as a movable body 12m.

  The drive system transducer 13 converts position information of the movable body 11m into, for example, a voltage signal. The detection system transducer 14 converts position information of the movable body 12m into, for example, a voltage signal.

  If a rotational motion occurs while the movable body 11m is vibrating in the x direction, the movable body 12m vibrates in the y direction due to Coriolis force. By detecting the displacement in the y direction of the movable body 12m based on the vibration in the y direction, it is possible to detect the angular velocity.

  Ideally, it is preferable that the vibration of the movable body 12m based on the Coriolis force includes only the vibration component in the y direction. However, in fact, since the movable body 11m vibrates in the x direction, the vibration of the movable body 12m also includes a vibration component in the x direction. The vibration component in the x direction included in the vibration of the movable body 12m is called a quadrature bias (also referred to as a quadrature error) and is a kind of disturbance signal. Therefore, the signal detected by the detection system transducer 14 includes the x-direction component in addition to the y-direction component. Therefore, it is important to reduce the orthogonal bias that is a disturbance signal component.

  In addition, since vibration starts in a stepwise manner, the step response also becomes a disturbance signal component. Therefore, it is also important to reduce the step response.

  As described above, in the physical quantity detection device such as the angular velocity detection device, the detection signal includes disturbance signal components such as the orthogonal bias and the step response. When such a disturbance signal component is included in the detection signal, the dynamic range of the detection circuit is occupied by the disturbance signal, and the SN ratio is greatly reduced. Therefore, it is important to effectively remove such disturbance signals.

  In order to eliminate the step response, it is effective to feed back a signal component based on the displacement in the y direction to the detection system. The cause of the step response is a transfer function of a secondary system having a resonance frequency in the detection system. Therefore, by performing feedback control, the peak of the transfer function can be flattened, and resonance can be suppressed. However, since a phase delay occurs due to the feedback control, the orthogonal bias component cannot be effectively removed.

  On the other hand, in order to remove the orthogonal bias component, it is effective to perform open loop control. By performing the open loop control, it is possible to make the phase delay almost zero, and it is possible to remove the quadrature bias component by synchronous detection. However, in the open loop control, the step response component can not be removed effectively because there is no feedback loop.

  Therefore, in the angular velocity detection apparatus (physical quantity detection apparatus) according to the present embodiment, both disturbance signal components of the step response and the orthogonal bias are reduced by combining feedback control and open loop control. However, this embodiment does not simply switch from feedback control to open loop control, but performs switching while gradually changing the ratio of both controls over time.

  FIG. 2 is a block diagram illustrating a specific configuration example of the angular velocity detection device (physical quantity detection device) according to the present embodiment.

  The angular velocity detection device (physical quantity detection device) shown in FIG. 2 includes a drive circuit 100, a mechanical sensor 200, a detection circuit 300, actuators 410, 420 and 430, and transducers 510 and 520.

  Drive circuit 100 includes a catch and release control 110 and an oscillator circuit 120. The capture and release control unit 110 controls the capture and release of the movable body (movable mass) 211 included in the drive system 210. This capture and release operation will be described in detail later. The oscillation circuit 120 forcibly vibrates the movable body (movable mass) 211 in the x direction (first direction), and operates mainly at startup.

  The mechanical sensor 200 includes a drive system (first vibration mechanism) 210 and a detection system (second vibration mechanism) 220. The drive system (first vibration mechanism) 210 and the detection system (second vibration mechanism) 220, the actuators 410, 420 and 430, and the transducers 510 and 520 are formed on the same substrate using micro electro mechanical systems (MEMS) technology. Is formed.

  The drive system 210 includes a movable body (first movable body) 211, a fixed end 212, a spring 213, and a damper 214. The movable body 211 is connected to the fixed end 212 via a spring 213, and can vibrate in the x direction (first direction) by the spring 213.

  The movable body 211 can be captured and released by the second actuator (capture and release mechanism) 420. That is, the second actuator 420 has a function of capturing the movable body 211 vibrating in the x direction and releasing the captured possible body 211 to vibrate in the x direction. The capture and release operation of the movable body 211 by the second actuator 420 is controlled by the capture and release control unit 110. When the movable body 211 is released from the second actuator 420, the movable body 211 freely vibrates in the x direction.

  Further, at the time of start-up, the movable body 211 is forcibly vibrated in the x direction by the third actuator 430 based on the oscillation signal from the oscillation circuit 120. During normal operation, the movable body can start free vibration by releasing the movable body 211 from the second actuator 420, but at startup, the movable body 211 is not captured by the second actuator 420. Unable to start free vibration. Therefore, a third actuator 430 is provided to force the movable body 211 to vibrate during startup.

  The detection system 220 includes a movable body (second movable body) 221, a fixed end 222, a spring 223, and a damper 224. The movable body 221 is connected to the fixed end 222 via a spring 223, and can be vibrated in the y direction (second direction) by the spring 223.

  The movable body 221 is also connected to the movable body 211 by a spring 230. Therefore, the movable body 221 vibrates in the x direction as the movable body 211 vibrates in the x direction. Further, while the movable body 221 vibrates in the x direction in accordance with the vibration of the movable body 211 in the x direction, the Coriolis force due to the rotational motion acts on the movable body 221, so that the movable body 221 is in the x direction. Vibrates in the vertical y direction. Therefore, it is possible to detect the angular velocity of the rotational motion by detecting the amplitude of the movable body 221 in the y direction.

  The detection circuit 300 includes a first amplification circuit 310, a second amplification circuit 320, a distribution control circuit 330, a multiplication circuit 340, and a phase adjustment circuit 350.

  The first amplification circuit 310 is for amplifying the signal from the first transducer 510. The first transducer 510 generates a first signal related to the position of the movable body 211 based on the vibration of the movable body 211 (hereinafter sometimes referred to as a first position signal for convenience). Therefore, the first amplifier circuit 310 amplifies the first position signal output from the first transducer 510. Specifically, the first transducer 510 is a capacitance of a variable capacitor configured by the movable body 211 and a first fixed electrode (not shown), and this capacitance change is output as a first position signal. It is a thing.

  The second amplification circuit 320 is for amplifying the signal from the second transducer 520. The second transducer 520 generates a second signal (hereinafter, for convenience, may be referred to as a second position signal) regarding the position of the movable body 221 based on the vibration of the movable body 221. Therefore, the second amplifier circuit 320 amplifies the second position signal output from the second transducer 520. Specifically, the second transducer 520 is a capacitance of a variable capacitor formed by the movable body 221 and a second fixed electrode (not shown), and this capacitance change is output as a second position signal. It is a thing. Based on the second position signal, the vibration amplitude of the movable body 221 can be obtained. Based on this amplitude, it is possible to calculate the angular velocity.

  The distribution circuit 330 generates a distribution control signal for distributing the signal amplified by the second amplifier circuit 320 to the first distribution signal and the second distribution signal based on the signal from the capture and release control unit 110. It is a thing.

  The multiplier circuit 340 multiplies the output signal of the first amplifier circuit 310 and a part of the output signal of the second amplifier circuit 320 (first distribution signal). In the multiplication circuit 340, synchronous detection is performed by a SW switching type multiplier controlled by the output of the binarized first amplification circuit 310.

  The phase adjustment circuit 350 adjusts the phase of the second distributed signal from the second amplification circuit 320.

  Hereinafter, the distribution circuit 330 and the phase adjustment circuit 350 will be described in detail.

  As already described, in the physical quantity detection device, a quadrature bias and a step response occur as disturbance signals. The step response occurs immediately after the movable body 211 is released from the second actuator (capture and release mechanism) 420. The orthogonal bias is a vibration component in the x direction included in the vibration of the movable body 211. In order to eliminate the step response, it is effective to feed back a signal component based on the displacement in the y direction to the detection system. However, since a phase delay occurs due to the feedback control, the orthogonal bias component cannot be effectively removed. On the other hand, in order to remove the orthogonal bias component, it is effective to perform open loop control. By performing open loop control, the phase delay can be made almost zero. However, in the open loop control, the step response component can not be removed effectively because there is no feedback loop.

  Therefore, in the present embodiment, both the step response and the orthogonal bias disturbance signal components are reduced by combining feedback control and open loop control. However, this embodiment does not simply switch from feedback control to open loop control, but performs switching while gradually changing the ratio of both controls over time. As described above, since the step response occurs immediately after the movable body 211 is released by the second actuator 420, the ratio of feedback control is made relatively large immediately after the release, and the open loop is performed over time. Increase the control ratio. That is, the ratio of the second distribution signal to the first distribution signal is decreased with the passage of time after the first movable body starts to vibrate. Such control makes it possible to effectively reduce both step response and quadrature bias disturbance signal components.

  As described above, the first distribution signal is input to the multiplication circuit 340, and the second distribution signal is input to the phase adjustment circuit 350. The signal whose phase has been adjusted by the phase adjustment circuit 350 is input to the first actuator 410. The first actuator 410 adjusts the vibration of the movable body 221 based on the signal adjusted by the phase adjustment circuit 350. That is, in the first actuator 410, the vibration of the movable body 221 is adjusted so that the step response is reduced.

  Next, the operation of the above-described angular velocity detection device (physical quantity detection device) will be described with reference to the timing chart shown in FIG.

  3, (a) shows the capture and release instruction signal, (b) shows the vibration state of the movable body 211, (c) shows the step response of the movable body 221, and (d) shows the distribution control circuit 330. The control signal (corresponding to the ratio of the second distribution signal) is shown.

  As can be seen from FIG. 3, the capturing and releasing operations are repeated, and the movable body 211 freely vibrates in the x direction during the releasing period. The step response of the movable body 221 gradually decreases from the time when the release period starts. In the distribution control circuit 330, the ratio of the second distribution signal is increased (for example, 100%) in the period in which the step response of the release period occurs, and then the ratio of the second distribution signal is gradually decreased. . Eventually, the ratio of the second distributed signal to the first distributed signal becomes zero, and measurement is performed in this state.

  As described above, according to the present embodiment, both the step response and the orthogonal bias can be effectively reduced, and the disturbance signal can be effectively removed.

  FIG. 4 is an electric circuit diagram showing a first configuration example of a part of the angular velocity detection device (physical quantity detection device) shown in FIG.

  The second transducer 520 includes a variable capacitor 521, and from the second transducer 520, a capacitance change (in response to the displacement position of the movable body 211) in response to the vibration of the movable body 211 serves as a signal as a second amplification circuit. 320 is output.

  The second amplification circuit 320 includes a voltage-current conversion circuit 321, a variable resistor 322, a variable resistor 323, a switch 324, a capacitor 325, and a resistor 326. The voltage signal input through the capacitor 325 is converted by the voltage-current conversion circuit 321 into a current signal. The current signal output from the voltage-current conversion circuit 321 is distributed to the first distribution signal and the second distribution signal by the control signal from the distribution control circuit 330. That is, the first distribution signal that passes through the variable resistor 322 is input to the multiplication circuit 340, and the second distribution signal that passes through the variable resistor 323 is input to the phase adjustment circuit 350. The variable resistor 322 and the variable resistor 323 use a triode region of a transistor, and the distribution control circuit 330 controls a transistor used in this triode region.

  The multiplication circuit 340 includes a multiplier 341, an operational amplifier 342 and an impedance element 343. In the multiplier circuit 340, the current input is switched, and the demodulated current is input to the feedback circuit, so that synchronous detection is performed and a physical quantity is detected.

  The phase adjustment circuit 350 includes an operational amplifier 351, an impedance element 352, an operational amplifier 353 and a resistor 354. Phase adjustment can be performed by changing the impedance of the impedance element 352. Since the transfer function of the detection system is a quadratic system, the phase delay is 180 degrees at the maximum. Therefore, oscillation occurs when a signal whose phase is delayed by 180 degrees is negatively fed back. Therefore, a signal is input to the actuator through an operational amplifier having a phase adjustment function such as a differentiation circuit. In general, by inputting the differentiated signal to the actuator, it becomes −90 degrees to +90 degrees in the entire frequency range, and oscillation can be prevented.

  The first actuator 410 includes a variable capacitor 411. In the first actuator 410, the vibration of the movable body 221 is adjusted based on the output of the phase adjustment circuit 350 so as to reduce the step response.

  FIG. 5 is an electric circuit diagram showing a second configuration example of a part of the angular velocity detector (physical quantity detector) shown in FIG.

  The second transducer 520 includes a variable capacitor 521, and from the second transducer 520, a capacitance change (in response to the displacement position of the movable body 211) in response to the vibration of the movable body 211 is a signal. It is output to the circuit 320.

  The second amplification circuit 320 includes a switch 324, a capacitor 325, an operational amplifier 327 and a resistor 328. The voltage signal input through the capacitor 325 is amplified by the operational amplifier 327.

  The signal output from the second amplifier circuit 320 is distributed to the first distribution signal and the second distribution signal by the control signal from the distribution control circuit 330. That is, the first distribution signal is input to the multiplication circuit 340, and the second distribution signal is input to the phase adjustment circuit 350. Specifically, by controlling the variable resistance 356 and the variable resistance 357 included in the phase adjustment circuit 350 according to the control signal from the distribution control circuit 330, the gain of the phase adjustment circuit 350 is adjusted, and the first distribution signal is generated. The ratio to the second distributed signal is adjusted.

  The multiplication circuit 340 includes a multiplier 341, an operational amplifier 342, an impedance element 344, and an impedance element 345. In the multiplication circuit 340, the voltage is switched, and when the demodulated voltage is input to the voltage amplification circuit, synchronous detection is performed and the physical quantity is detected. Note that this circuit can also process signals in a differential configuration.

  The phase adjustment circuit 350 includes an operational amplifier 355, a variable resistor 356, and a variable resistor 357. When a variable capacitance element is used, the signal to be detected can be extracted as a differential current by performing constant voltage control on the variable capacitance element. Therefore, it is possible to include in the phase adjustment circuit a differentiation function that advances the phase by 90 degrees, and it is possible to reduce the circuit area. As described above, oscillation occurs when a signal delayed by 180 degrees is negatively fed back, but in the configuration of FIG. 5, since the second amplifier circuit 320 includes a differential function, the phase adjustment circuit is a simple amplifier circuit. It is configurable. The principle by which a differential signal can be output is as follows. When a constant voltage is applied to the variable capacitor, a charge (Q = CV) is given to the variable capacitor. When the capacitance of the variable capacitor slightly changes, ΔQ = ΔC × V. Therefore, by performing time differentiation, the differential value of the capacitance change is output as a current as I = ΔQ / Δt = ΔC / Δt × V.

  The first actuator 410 includes a variable capacitor 411. In the first actuator 410, the vibration of the movable body 221 is adjusted based on the output of the phase adjustment circuit 350 so as to reduce the step response.

  FIG. 6 is an electric circuit diagram showing a detailed configuration of the switching control circuit 330. The switching control circuit 330 is composed of operational amplifiers A1 and A2, transistors M1 to M5, transistors MDSW1 and MDSW2, current sources I1 to I5, a capacitor Cint, and a switch RST. By using the circuit of FIG. 6, the ratio of the voltage gradually changes, and the two output signals are distributed so that the sum of the currents flowing through the transistors MDSW1 and MDSW2 controlled by Cont1 and Cont2 becomes constant. Output from

  In the embodiment described above, while the movable body 211 is captured by the second actuator 420, the first amplification circuit 310, the second amplification circuit 320, the distribution control circuit 330, the multiplication circuit 340, and the phase The operation of the adjustment circuit 350 may be stopped. In this way, power consumption can be reduced.

  In the embodiment described above, the operation of the distribution control circuit 330 may be stopped after the ratio of the second distributed signal to the first distributed signal finally becomes zero. In this way, power consumption can be reduced.

  Moreover, although the variable capacitor element is used as a transducer element in the embodiment described above, a variable resistive element or a piezoelectric element may be used instead of the variable capacitor.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

11 ... drive system 12 ... detection system 13 ... drive system transducer 14 ... detection system transducer 100 ... drive circuit 110 ... capture and release control unit 120 ... oscillation circuit 200 ... mechanical sensor 210 ... drive system 211 ... movable body 212 ... fixed end 213 ... spring 214 ... damper 220 ... detection system 221 ... movable body 222 ... fixed end 223 ... spring 224 ... damper 230 ... spring 300 ... detection circuit 310 ... first amplification circuit 320 ... second amplification circuit 321 ... voltage current conversion Circuit 322 ... variable resistance 323 ... variable resistance 324 ... switch 325 ... capacitor 326 ... resistance 327 ... operational amplifier 328 ... distribution control circuit 340 ... multiplication circuit 341 ... multiplier 342 ... operational amplifier 343, 344, 345 ... impedance element 350: Phase adjustment circuit 351 Operational amplifier 352 ... impedance elements 353 ... operational amplifier 354 ... resistor 355 ... operational amplifier 356, 357 ... variable resistance 410,420.430 ... actuator 411 ... variable capacitor 510, 520 ... transducer 521 ... variable capacitor

Claims (11)

A first vibration mechanism including a first movable body capable of vibrating in a first direction;
A second movable body that vibrates in the first direction along with the vibration of the first movable body in the first direction and that can vibrate in a second direction perpendicular to the first direction. A second vibration mechanism including
A first transducer that generates a first signal related to the position of the first movable body based on the vibration of the first movable body;
A second transducer that generates a second signal related to the position of the second movable body based on the vibration of the second movable body;
A first amplifier circuit for amplifying the first signal;
A second amplification circuit that amplifies the second signal;
A distribution control circuit for distributing the signal amplified by the second amplifier circuit into a first distribution signal and a second distribution signal;
A multiplication circuit for multiplying an output of the first amplification circuit and the first distribution signal;
A phase adjustment circuit that adjusts the phase of the second distributed signal;
A first actuator that adjusts the vibration of the second movable body based on the signal adjusted by the phase adjustment circuit;
With
The ratio of the second distribution signal to the first distribution signal decreases with time after the first movable body starts to vibrate. A second actuator that captures the first movable body vibrating in the first direction and releases the captured first possible body to vibrate in the first direction; The physical quantity detection device according to claim 1. While the first movable body is captured by the second actuator, operations of the first amplification circuit, the second amplification circuit, the distribution control circuit, the multiplication circuit, and the phase adjustment circuit The physical quantity detection device according to claim 2, wherein the physical quantity detection device is stopped. The physical quantity detection device according to claim 1, further comprising a third actuator that forcibly vibrates the first movable body in the first direction. The physical quantity detection device according to claim 1, wherein a ratio of the second distribution signal to the first distribution signal finally becomes zero. The physical quantity detection device according to claim 5, wherein after the ratio of the second distribution signal to the first distribution signal finally becomes zero, the operation of the distribution control circuit is stopped. The first vibration mechanism, the second vibration mechanism, the first transducer, the second transducer, the first actuator, the second actuator, and the third actuator are provided on the same substrate. The physical quantity detection device according to claim 1, wherein The first vibration mechanism, the second vibration mechanism, the first transducer, the second transducer, the first actuator, the second actuator and the third actuator are formed by MEMS technology The physical quantity detection device according to claim 1, wherein: The second movable body includes the second movable body while the second movable body vibrates in the first direction in accordance with the vibration of the first movable body in the first direction. The physical quantity detection device according to claim 1, wherein the physical quantity detection device vibrates in the second direction by rotational movement acting on the body. The physical quantity detection device according to claim 1, wherein the second transducer includes a variable capacitor, and the second signal is generated based on a capacitance of the variable capacitor. The physical quantity detection device according to claim 1, wherein a signal based on an angular velocity of the second movable body is output from the multiplication circuit.

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