GYRO SENSOR DEVICE

Abstract

Gyro sensor device (51) with a control section (5) that provides a control signal (Vd) which serves to vibrate a sensor element (3) of a vibration-type gyro sensor in a control axis direction at the sensor element (3); and a processing unit (53) that receives a first vibration signal (Vm) having an amplitude proportional to a control vibration amplitude, which is a vibration amplitude in the control axis direction of the sensor element (3), and a second vibration signal (Vc) having an amplitude proportional to the Coriolis force (fc) generated in the sensor element (3) due to an angular velocity of the sensor element (3), wherein the processing unit (53) has: a switching section (55) which is controlled by a control section (63) at a predetermined period of the first vibration signal (Vm) to alternately switch between the first vibration signal (Vm) and the second vibration signal (Vc) at a predetermined period of the first vibration signal (Vm), and to select and output one of the first vibration signal (Vm) and the second vibration signal (Vc) as a selection signal; a sensing section (57) comprising the control section (63) and configured to receive the selection signal from the switch section (55), to output a first sensing signal (Dm) indicating an amplitude of the first vibration signal (Vm) when the selection signal is the first vibration signal (Vm), and to output a second sensing signal (Dc) indicating an amplitude of the second vibration signal (Vc) when the selection signal is the second vibration signal (Vc); and a ratio calculation section (58) configured to calculate a ratio of a value of the second detection signal (Dc) to a value of the first detection signal (Dm) as a ratio of the Coriolis force (fc) to the control vibration amplitude, and to output the calculated ratio as a result of the detection (Dso) of the angular velocity of the sensor element (3).

Description

REFERENCE TO APPLICATIONS OF THE SAME GENUS

[0001] This application is based on or claims the benefit of priority from prior Japanese Patent Application No. 2016-101565, filed on May 20, 2016, the disclosure of which is incorporated herein by reference. STATE OF THE ART (Technical field)

[0002] The present invention relates to a gyro sensor device. (State of the art)

[0003] JP 2000-136 934 A discloses a vibration detecting means providing a detection signal processor that reduces the change in the level of a detection output of the angular velocity with respect to a change in a drive amplitude and a drive frequency by calculating an angular velocity value using the ratio of an amplitude in a drive direction detected by the vibration detecting means to an amplitude in a detection direction as a parameter.

[0004] US 2003 / 0 039 325 A1 discloses a synchronous detection method and apparatus used for sampling a signal component synchronous with a reference signal from an input signal, and a sensor signal detection device utilizing the synchronous detection, wherein high-frequency noise resulting from the synchronous detection can be efficiently minimized without the need for a low-pass filter requiring a large time constant.

[0005] As a gyro sensor device that detects angular velocity using a vibration-type gyro sensor, for example, a device is disclosed in JP H09-33259A. The device disclosed in JP H09-33259A includes a phase shift circuit with a temperature compensation circuit as a circuit that provides a drive signal to a piezoelectric element serving as a sensor element. The phase shift circuit with a temperature compensation circuit controls the drive signal to the piezoelectric element so that the output voltage of the piezoelectric element becomes permanently constant regardless of temperature changes.

[0006] In a vibration-type gyro sensor, a sensor element vibrates to detect angular velocity in the drive axis direction by receiving a drive signal. The vibration in the drive axis direction of the sensor element is called drive vibration. The amplitude of the drive vibration is called drive vibration amplitude. When the sensor element vibrating in the drive axis direction rotates around a rotation axis perpendicular to the drive axis direction, that is, when angular velocity is generated in the sensor element, a Coriolis force is generated in the detection axis direction perpendicular to both the drive axis direction and the rotation axis. The Coriolis force causes the sensor element to vibrate in the detection axis direction. The vibration in the detection axis direction of the sensor element is called detection vibration.The amplitude of the detection vibration is called detection vibration amplitude.

[0007] The detection vibration amplitude is proportional to the Coriolis force, and the Coriolis force is proportional to the driving vibration speed (hereinafter referred to as the driving vibration speed) and the angular velocity. The driving vibration amplitude is proportional to the driving vibration speed.

[0008] Thus, in the gyro sensor device disclosed in JP H09-33259A, it is assumed that the drive vibration velocity is always constant by performing feedback control to adjust a drive signal so that the drive vibration amplitude is constant. Here, it is assumed that the detection vibration amplitude always indicates a true angular velocity. Then, an angular velocity is detected by electrically detecting the detection vibration amplitude.

[0009] The gyro sensor device described above has the following problems (1) to (3).

[0010] (1) To perform feedback control to make a driving vibration amplitude constant, for example, at least a comparison circuit and an AGC circuit are required. The comparison circuit compares an actual driving vibration amplitude with a target value in real time. The AGC circuit adjusts a driving signal to the sensor element according to a comparison result of the comparison circuit. Since the comparison circuit and the AGC circuit are large in size, the gyro sensor device cannot be downsized, resulting in an increase in power consumption and manufacturing costs. Note that AGC is an abbreviation for "automatic gain control." In particular, in recent IoT application systems, a number of high-precision sensors are required.However, since conventional gyro sensor devices cannot meet scaling requirements, they are difficult to apply to IoT application systems. Note that IoT is an abbreviation for "Internet of Things."

[0011] (2) In order to maintain a constant driving vibration amplitude, a variation in detection sensitivity cannot be corrected in the feedback control. When a resonance frequency of the sensor element changes due to temperature, time lapse, or the like, a driving vibration speed changes, causing the detection sensitivity to vary. Thus, it is difficult to apply the conventional gyro sensor device to a system requiring high accuracy, such as an automatic operating system for a vehicle.

[0012] (3) Since the driving vibration amplitude must be constant, the maximum vibration amplitude of the sensor element cannot be used. This means that since the sensing capability of the sensor element is always limited, the angular velocity cannot be detected with the maximum sensitivity of the sensor element. Consequently, to achieve high sensitivity, the sensor element must be designed to have a higher sensitivity than necessary, which prevents the reduction of the sensor element's dimensions and manufacturing costs.

[0013] The above-described object is achieved by the gyro sensor device according to claim 1. Further developments according to the invention are the subject of the subclaims. SUMMARY

[0014] An embodiment provides a gyro sensor device that can be reduced in size and increased in accuracy and sensitivity.

[0015] As one aspect of the embodiment, a gyro sensor device includes: a drive section that supplies a drive signal for vibrating a sensor element of a vibration-type gyro sensor in a drive axis direction to the sensor element; and a processing unit that receives a first vibration signal having an amplitude proportional to a drive vibration amplitude, which is a vibration amplitude in the drive axis direction of the sensor element, and a second vibration signal having an amplitude proportional to the Coriolis force generated in the sensor element due to an angular velocity of the sensor element.The processing unit is configured to calculate a ratio of the Coriolis force to the driving vibration amplitude based on the first vibration signal and the second vibration signal and output a result of the calculation as a result of detecting the angular velocity of the sensor element. SHORT DESCRIPTION OF THE DRAWING

[0016] In the attached drawing: Fig. 1 is a block diagram showing a configuration of a gyro sensor device according to a first embodiment; Fig. 2 is a diagram showing configurations of a first pulse delay circuit and a first pulse position detection circuit; Fig. 3 is a diagram showing a configuration of a delay unit; Fig. 4 is a diagram illustrating the operation of a first control unit; Fig. 5 is a block diagram showing a configuration of a gyro sensor device according to a second embodiment; and Fig. 6 is a block diagram showing a configuration of a gyro sensor device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] In the following, embodiments are described with reference to the drawing. (1. First embodiment)[1-1. Configuration]

[0018] A gyro sensor device 1 of the first embodiment shown in Fig. 1 is installed in a vehicle such as a passenger car. The gyro sensor device 1 includes a sensor element (hereinafter referred to as an element 3) of a vibration-type gyro sensor and a drive signal generating circuit 5.

[0019] The element 3 is, for example, a tuning fork-like element. The element 3 vibrates in the drive axis direction by receiving a drive signal Vd having a predetermined frequency and output from the drive signal generating circuit 5. The vibration in the drive axis direction is a drive vibration. In the present embodiment, the horizontal direction is in Fig. 1 is defined as an x-axis direction, which is the control axis direction.

[0020] When the element 3 vibrating in the drive axis direction rotates about a rotation axis perpendicular to the drive axis direction, that is, when an angular velocity is generated in the element 3, the Coriolis force fc is generated in the detection axis direction perpendicular to both the drive axis direction and the rotation axis. In the present embodiment, the forward-backward direction in Fig. 1 is defined as a y-axis direction, which is the detection axis direction.

[0021] The Coriolis force fc is proportional to the driving vibration velocity and the angular velocity of element 3. Since the driving vibration amplitude is proportional to the driving vibration velocity, the Coriolis force fc is proportional to the driving vibration amplitude and the angular velocity of element 3. The Coriolis force fc causes vibration in the sensing axis direction (i.e., sensing vibration). Furthermore, the sensing vibration amplitude is proportional to the Coriolis force fc.

[0022] In addition, the gyro sensor device 1 has a first vibration signal output circuit 7 and a second vibration signal output circuit 9.

[0023] In a monitor electrode (electrode for monitoring) of the element 3, the charge changes depend on the drive vibration. The first vibration signal output circuit 7 converts the change in charge in the monitor electrode into a voltage signal to output a first vibration signal Vm. The first vibration signal Vm oscillates with respect to a predetermined oscillation center voltage Vzm, which is higher than 0 V, and has an amplitude proportional to the drive vibration amplitude. The frequency of the first vibration signal Vm is the same as the frequency of the drive signal Vd.

[0024] In a detection electrode (electrode for detection) of the element 3, the charge changes depend on the detection vibration. The second vibration signal output circuit 9 converts the change in charge in the detection electrode into a voltage signal to output a second vibration signal Vc. The second vibration signal Vc oscillates with respect to a predetermined oscillation center voltage Vzc higher than 0 V and has an amplitude proportional to the detection vibration amplitude. Since the detection vibration amplitude is proportional to the Coriolis force fc, the amplitude of the second vibration signal Vc is proportional to the Coriolis force fc. Therefore, the amplitude of the second vibration signal Vc is proportional to a drive vibration amplitude and an angular velocity. The frequency of the second vibration signal Vc is the same as the frequency of the first vibration signal Vm.The phases of the first vibration signal Vm and the second vibration signal Vc are shifted by 90° from each other. Note that the oscillation mean voltage Vzm of the first vibration signal Vm and the oscillation mean voltage Vzc of the second vibration signal Vc may or may not be the same.

[0025] The gyro sensor device 1 has a processing unit 11. The processing unit 11 receives the first vibration signal Vm and the second vibration signal Vc.

[0026] The processing unit 11 calculates a ratio of the Coriolis force fc to the driving vibration amplitude based on the first vibration signal Vm and the second vibration signal Vc, and outputs the result of the calculation as an angular velocity detection result (hereinafter referred to as angular velocity detection result) Dso of the element 3.

[0027] The processing unit 11 has, as components for calculating the ratio, a first detection section 21, a second detection section 22 and a ratio calculation section 23.

[0028] The first detection section 21 outputs a first detection signal Dm indicative of the driving vibration amplitude based on the first vibration signal Vm. The second detection section 22 outputs a second detection signal Dc indicative of the Coriolis force fc based on the second vibration signal Vc. In the present embodiment, the first detection signal Dm and the second detection signal Dc are digital signals. The ratio calculation section 23 receives the first detection signal Dm and the second detection signal Dc. The operation of the ratio calculation section 23 will be described later.

[0029] The first detection section 21 includes a first pulse delay circuit 31 as a component for outputting the first detection signal Dm. Additionally, the first detection section 21 includes a first pulse position detection circuit 32, a first control section 33, and a first calculation section 34.

[0030] As in Fig. As shown in Figure 2, the first pulse delay circuit 31 includes a plurality of delay units 35 configured such that the speed (hereinafter referred to as pulse propagation speed) at which a received pulse signal (hereinafter referred to as pulse) propagates to the output side increases in proportion to a voltage value of the first vibration signal Vm. The plurality of delay units 35 are connected in series.

[0031] In particular, as in Fig. 2 and Fig. As shown in Figure 3, each of the n delay units 35 configuring the first pulse delay circuit 31 is formed of two-stage inverter gate circuits 36 connected in series. Note that n is an integer of 2 or more. The first vibration signal Vm is supplied as the power Vin of the delay units 35, that is, the power Vin of the inverter gate circuits 36. Thus, the pulse propagation speed in the delay units 35 is controlled by the first vibration signal Vm. Specifically, the pulse propagation speed in the delay units 35 increases in proportion to a voltage value of the first vibration signal Vm.

[0032] The first pulse delay circuit 31 receives a high-level pulse Pa from the outside. The pulse Pa is input to the delay unit 35 of the first stage of the n delay units 35 that configure the first pulse delay circuit 31. Thus, each of the series-connected delay units 35 outputs the pulse Pa at the time point at which the pulse Pa has passed through the delay units 35. Hereinafter, the output signals P1 to Pn of the delay units 35 are referred to as a delay pulse group.

[0033] In addition, the first pulse position detection circuit 32, as shown in Fig. 2, a self-holding circuit 37 and an encoder 38.

[0034] The first pulse position detection circuit 32 receives a clock CKa from the outside. Then, the clock CKa is input to the self-hold circuit 37.

[0035] The self-hold circuit 37 stores information about the states of the delay pulse group P1 to Pn from the first pulse delay circuit 31, for example, at the rise time of the clock signal CKa. The state of the delay pulse group P1 to Pn is a high level or a low level.

[0036] The encoder 38 outputs a digital signal indicating the number of delay units 35 through which the pulse Pa has passed, based on the state of the delay pulse group P1 to Pn stored in the self-hold circuit 37. The digital signal output by the encoder 38 becomes an output signal Do1 of the first pulse position detection circuit 32.

[0037] Therefore, the digital signal indicating the number of delay units 35 that the pulse Pa has passed through during a period from the time a high-level pulse Pa is input to the first pulse delay circuit 31 to the time a rising edge is generated in the clock CKa becomes the output signal Do1 of the first pulse position detecting circuit 32. The output signal Do1 is also a signal obtained by converting an integrated value of the first vibration signal Vm during the period into a digital value.

[0038] The first control section 33 performs at least the output of the pulse Pa to the first pulse delay circuit 31 and outputs the clock CKa to the first pulse position detection circuit 32. The clock CKa is also input to the first calculation section 34. Then, the first calculation section 34 generates the first detection signal Dm from the output signal Do1 of the first pulse position detection circuit 32 and outputs the first detection signal Dm. Operations of the first control section 33 and the first calculation section 34 will be described later.

[0039] The second detection section 22 includes a second pulse delay circuit 41 as a component for outputting the second detection signal Dc. Additionally, the second detection section 22 includes a second pulse position detection circuit 42, a second control section 43, and a second calculation section 44.

[0040] The second pulse delay circuit 41 includes a plurality of delay units configured such that the pulse propagation speed increases proportionally to a voltage value of the second vibration signal Vc. Also in the second pulse delay circuit 41, the plurality of delay units are connected in series. Specifically, although the second pulse delay circuit 41 has the same configuration as the first pulse delay circuit 31, the second pulse delay circuit 41 differs from the first pulse delay circuit 31 in that the second vibration signal Vc is supplied as the power Vin of the delay units 35. Note that in Fig. 1 Pb is used as a sign of a pulse input to the second pulse delay circuit 41.

[0041] In addition, the second pulse position detection circuit 42 has the same configuration as that of the first pulse position detection circuit 32. That is, the second pulse position detection circuit 42 includes, as in the first pulse position detection circuit 32, the self-hold circuit 37 and the encoder 38. It is noted that, as in Fig. 1, CKb is used as a symbol for a clock input to the second pulse position detection circuit 42.

[0042] Thus, in the second detection section 22, the digital signal indicating the number of delay units 35 that the pulse Pb has passed through during a period from the time a high-level pulse Pb is input to the second pulse delay circuit 41 to the time a rising edge is generated in the clock CKb becomes the output signal Do2 of the second pulse position detection circuit 42.

[0043] The second control section 43 performs at least the output of the pulse Pb to the second pulse delay circuit 41 and outputs the clock CKb to the second pulse position detection circuit 42. The clock CKb is also input to the second calculation section 44. The second calculation section 44 generates the second detection signal Dc from the output signal Do2 of the second pulse position detection circuit 42 and outputs the second detection signal Dc. Operations of the second control section 43 and the second calculation section 44 will be described later. [1-2. Procedure of the first tax section]

[0044] The time at which the first vibration signal Vm crosses the oscillation center voltage Vzm is called the zero-crossing time point. Among the zero-crossing time points, the time at which the first vibration signal Vm crosses the oscillation center voltage Vzm from bottom to top is called a high-side zero-crossing time point. The time at which the first vibration signal Vm crosses the oscillation center voltage Vzm from top to bottom is called a low-side zero-crossing time point. In addition, a half-period during which the first vibration signal Vm is greater than the oscillation center voltage Vzm is called a high-side half-period. A half-period during which the first vibration signal Vm is smaller than the oscillation center voltage Vzm is called a low-side half-period. Such formulations are used similarly for the second vibration signal Vc.

[0045] The first control section 33 performs the following operations <m1>and <m2>through.

[0046] <m1>The first control section 33 makes the pulse Pa to the first pulse delay circuit 31 to a high level at any of the high-side zero-crossing timings of the first vibration signal Vm, as at the time t1 in Fig. 4. Note that the time at which the pulse Pa to the first pulse delay circuit 31 becomes high is called the start time of the pulse Pa.

[0047] <m2>Then the first control section 33, as in Fig. 4, the first control section 33 outputs the clock CKa to the first pulse position detection circuit 32 so that it rises at each zero-crossing time point of the first vibration signal Vm. The first control section 33 specifies the zero-crossing time points of the first vibration signal Vm based on, for example, the drive signal Vd.

[0048] Thus, the first pulse position detecting circuit 32 outputs a digital signal indicative of the number of delay units 35 that the pulse Pa has passed through from the start time of the pulse Pa as the output signal Do1 at each of the zero-crossing timings of the first vibration signal Vm. [1-3. Process of the first calculation section]

[0049] The first calculation section 34 operates synchronously with the clock CKa and acquires an updated output signal Do1.

[0050] The first calculation section 34 calculates a value (hereinafter Nm1) obtained by subtracting a value of the output signal Do1 updated at the immediately previous high-side zero-crossing time point of the first vibration signal Vm from a value of the output signal Do1 updated at the low-side zero-crossing time point. Nm1 is the number of delay units 35 that the pulse Pa has passed through in the first pulse delay circuit 31 during the high-side half-period of the first vibration signal Vm. In addition, Nm1, as shown in Fig. 4, an integrated value S1 during the high-side half-period of the first vibration signal Vm.

[0051] In addition, the first calculation section 34 calculates a value (hereinafter Nm2) obtained by subtracting a value of the output signal Do1 updated at the immediately previous low-side zero-crossing time point of the first vibration signal Vm from a value of the output signal Do1 updated at the high-side zero-crossing time point. Nm2 is the number of delay units 35 that the pulse Pa has passed through in the first pulse delay circuit 31 during the low-side half-period of the first vibration signal Vm. In addition, Nm2, as shown in Fig. 4, an integrated value S2 during the low-side half-period of the first vibration signal Vm.

[0052] Then, the first calculation section 34 calculates the difference between the successively calculated Nm1 and Nm2, ie, Nm1 - Nm2. The first calculation section 34 outputs a digital signal indicating Nm1 - Nm2 as the first detection signal Dm.

[0053] The first detection signal Dm, generated as described above, corresponds to a value obtained by subtracting the integrated value S2 during the low-side half-period of the first vibration signal Vm from the integrated value S1 during the high-side half-period of the first vibration signal Vm, ie, S1 - S2, and indicates the amplitude of the first vibration signal Vm. Thus, the first detection signal Dm indicates the drive vibration amplitude. [1-4. Procedure of the second tax section]

[0054] The second control section 43 also performs an operation similar to that of the first control section 33. That is, the second control section 43 performs the following operations <c1>and <c2>through.

[0055] <c1>The second control section 33 makes the pulse Pb to the second pulse delay circuit 41 a high level at any of the high-side zero-crossing timings of the second vibration signal Vc as at the time t1 in Fig. 4. Note that the time at which the pulse Pb to the second pulse delay circuit 41 becomes high is called the start time of the pulse Pb.

[0056] <c2>Then, the second control section 43 outputs the clock CKb to the second pulse position detection circuit 42 so that it rises at each of the zero-crossing timings of the second vibration signal Vc. The second control section 43 specifies the zero-crossing timings of the first vibration signal Vc based on, for example, the drive signal Vd or the zero-crossing timing of the first vibration signal Vm.

[0057] Thus, the second pulse position detecting circuit 42 outputs a digital signal indicating the number of delay units 35 that the pulse Pb has passed through from the start time of the pulse Pa as the output signal Do2 at each of the zero-crossing timings of the second vibration signal Vc. [1-5. Process of the second calculation section]

[0058] The second calculation section 44 also works as in the first calculation section 34.

[0059] That is, the second calculation section 44 operates synchronously with the clock CKb and acquires an updated output signal Do2.

[0060] Then, the second calculation section 44 calculates a value (hereinafter, Nc1) obtained by subtracting a value of the output signal Do2 updated at the immediately previous high-side zero-crossing time point of the second vibration signal Vc from a value of the output signal Do2 updated at the low-side zero-crossing time point. Nc1 is the number of delay units 35 that the pulse Pb has passed through in the second pulse delay circuit 41 during the high-side half-period of the second vibration signal Vc. In addition, Nc1 indicates an integrated value during the high-side half-period of the second vibration signal Vc.

[0061] In addition, the second calculation section 44 calculates a value (hereinafter, Nc2) obtained by subtracting a value of the output signal Do2 updated at the immediately previous low-side zero-crossing time point of the second vibration signal Vc from a value of the output signal Do2 updated at the high-side zero-crossing time point. Nc2 is the number of delay units 35 that the pulse Pb has passed through in the second pulse delay circuit 41 during the low-side half-period of the second vibration signal Vc. In addition, Nc2 indicates an integrated value during the low-side half-period of the second vibration signal Vc.

[0062] Then, the second calculation section 44 calculates the difference between the successively calculated Nc1 and Nc2, that is, Nc1 - Nc2. The second calculation section 44 outputs a digital signal indicative of Nc1 - Nc2 as the second detection signal Dc.

[0063] The second detection signal Dc, generated as described above, corresponds to a value obtained by subtracting the integrated value during the low-side half-period of the second vibration signal Vc from the integrated value during the high-side half-period of the second vibration signal Vc, and indicates the amplitude of the second vibration signal Vc. Thus, the second detection signal Dc indicates the Coriolis force fc. [1-6. Process of the ratio calculation section]

[0064] The ratio calculation section 23 receives the first detection signal Dm from the first detection section 21 and receives the second detection signal Dc from the second detection section 22. Then, the ratio calculation section 23 calculates a ratio of a value of the second detection signal Dc to a value of the first detection signal Dm, ie, Dc / Dm, as a ratio of the Coriolis force to the driving vibration amplitude, and outputs the calculated ratio as the angular velocity detection result Dso. The angular velocity detection result Dso output from the ratio calculation section 23 is also a digital signal.

[0065] It is noted that part or all of the ratio calculation section 23, the first control section 33, the first calculation section 34, the second control section 43, and the second calculation section 44 may be configured, for example, by one or more microcomputers or hardware formed from the combination of logic circuits, analog circuits, and the like. [1-7. Advantageous Effects of the First Embodiment]

[0066] According to the first embodiment, the following advantageous effects can be provided.

[0067] (1a) Without the control to make the driving vibration amplitude constant, even if a temperature change is caused in the element 3, the angular velocity detection result Dso can always be obtained with high accuracy.

[0068] For example, if the driving vibration amplitude increases due to the temperature change, the generated Coriolis force fc also increases. However, if the angular velocity is not changed, the ratio of the Coriolis force fc to the driving vibration amplitude does not change. Therefore, even if the driving vibration amplitude changes due to the temperature change, if the angular velocity is not changed, Dc / Dm, which is a ratio of a value of the second detection signal Dc to a value of the first detection signal Dm, does not change. That is, the angular velocity detection result Dso output from the ratio calculation section 23 of the processing unit 11 does not change.

[0069] According to the above-described gyro sensor device 1 of the first embodiment, a reduction in size can be achieved because a feedback control circuit for making the drive vibration amplitude constant is not required, and high accuracy can be achieved, allowing angular velocity to be detected with high accuracy regardless of temperature changes. Furthermore, using the Dc / Dm calculation result as the angular velocity detection result Dso is also effective against the drift of the power supply voltage and the manufacturing tolerance.

[0070] (1b) Even if a resonance frequency of the element 3 changes due to temperature change or the like and the driving vibration speed changes, resulting in a change in the driving vibration amplitude, if the angular velocity is not changed, the ratio of the Coriolis force fc to the driving vibration amplitude does not change, that is, the angular velocity detection result Dso calculated by the processing unit 11 does not change. Thus, a variation in the detection sensitivity according to the change in a resonance frequency of the element 3 can also be corrected.

[0071] (1c) The maximum driving vibration amplitude of element 3 can be used. That is, an angular velocity can be detected with the maximum sensitivity of element 3. Thus, an angular velocity can be detected with high sensitivity.

[0072] (1d) The processing unit 11 includes the first detection section 21 that outputs the first detection signal Dm based on the first vibration signal Vm, the second detection section 22 that outputs the second detection signal Dc based on the second vibration signal Vc, and the ratio calculation section 23 that calculates Dc / Dm as a ratio of the Coriolis force fc to the driving vibration amplitude. The processing unit 11 can be provided as a circuit that is small in size and consumes little power, with low manufacturing costs, by using the latest standard electronic circuit technology.

[0073] (1e) The first detection section 21 is configured to output the first detection signal Dm using the first pulse delay circuit 31 configured by the plurality of delay units 35, by which the pulse propagation speed increases in proportion to a voltage value of the first vibration signal Vm. The second detection section 22 is also configured to output the second detection signal Dc using the second pulse delay circuit 41 configured by the plurality of delay units 35, by which the pulse propagation speed increases in proportion to a voltage value of the second vibration signal Vc. Thus, the first detection section 21 and the second detection section 22 can be configured by small-scale digital circuits.

[0074] (1f) The first detection section 21 outputs a digital signal indicative of the difference between Nm1, which is the number of delay units 35 that a pulse has passed during the high-side half-period of the first vibration signal Vm, and Nm2, which is the number of delay units 35 that the pulse has passed during the low-side half-period of the first vibration signal Vm, as the first detection signal Dm. Similarly, the second detection section 22 outputs a digital signal indicative of the difference between Nc1, which is the number of delay units 35 that a pulse has passed during the high-side half-period of the second vibration signal Vc, and Nc2, which is the number of delay units 35 that the pulse has passed during the low-side half-period of the second vibration signal Vc, as the second detection signal Dc.

[0075] Therefore, a value obtained by subtracting the integrated value during the low-side half-period of the first vibration signal Vm from the integrated value during the high-side half-period of the first vibration signal Vm can be adopted as the first detection signal Dm. Similarly, a value obtained by subtracting the integrated value during the low-side half-period of the second vibration signal Vc from the integrated value during the high-side half-period of the second vibration signal Vc can be adopted as the second detection signal Dc. Therefore, even if noise is generated in the first vibration signal Vm, the influence of the noise on the first detection signal Dm can be suppressed. Similarly, even if noise is generated in the second vibration signal Vc, the influence of the noise on the second detection signal Dc can be suppressed.Thus, the accuracy of detecting an angular velocity can be prevented from decreasing due to disturbance.

[0076] In the present embodiment, the drive signal generating circuit 5 corresponds to a drive section. (2. Second embodiment)

[0077] Descriptions of configurations common to those of the first embodiment will be omitted, and differences from the first embodiment will be primarily described. The same reference numerals as those of the first embodiment indicate the same components and signals. These are common to other embodiments described later. [2-1. Configurations]

[0078] As shown in Fig. 5, a gyro sensor device 51 of the second embodiment differs from the gyro sensor device of the first embodiment in that the gyro sensor device 51 includes a processing unit 53 instead of the processing unit 11. The processing unit 53 has the same functions as those of the processing unit 11. The processing unit 53 includes a switch 55, a detection section 57, and a ratio calculation section 58.

[0079] The switch 55 receives the first vibration signal Vm and the second vibration signal Vc. The switch 55 selects and outputs either the first vibration signal Vm or the second vibration signal Vc as a selection signal. The switch 55 is controlled by a control section 63 described later.

[0080] The detection section 57 includes a pulse delay circuit 61, a pulse position detection circuit 62, a control section 63, and a calculation section 64.

[0081] The pulse delay circuit 61 has the same configuration as the first pulse delay circuit 31 of the first embodiment. Note that a selection signal from the switch 55 is supplied as the power Vin of the delay units 35 in the pulse delay circuit 61. That is, the pulse delay circuit 61 performs A / D conversion for the selection signal.

[0082] The pulse position detection circuit 62 has the same configuration as that of the first pulse position detection circuit 32 of the first embodiment.

[0083] The control section 63 controls at least the switching of the switch 55, outputs the pulse Pa to the pulse delay circuit 61, and outputs the clock CKa to the pulse position detection circuit 62. The clock CKa is also input to the calculation section 64. Then, the calculation section 64 generates the first detection signal Dm and the second detection signal Dc from the output signal Do1 of the pulse position detection circuit 62 and outputs the first detection signal Dm and the second detection signal Dc. [2-2. Tax section procedure]

[0084] The control section 63 performs the same operation as that of the first control section 33 of the first embodiment, ie, the operations <m1>and <m2>in a state where the control section 63 causes the switch 55 to output the first vibration signal Vm as a selection signal. This operation is referred to as the first operation.

[0085] In addition, the control section 63 performs the same operation as that of the second control section 43 of the first embodiment, that is, the operations <c1>and <c2>in a state in which the control section 63 causes the switch 55 to output the second vibration signal Vc as a selection signal. This process is referred to as the second process. It is noted that the control section 63 performs the second process shown in <c1>and <c2>of the first embodiment in a state where the word "pulse Pb" is changed to "pulse Pa" and the word "clock CKb" is changed to "clock CKa".

[0086] Then, the control section 63 performs the first operation and the second operation alternately, for example, at regular intervals or predetermined periods of the first vibration signal Vm. [2-3. Calculation unit process]

[0087] When the control section 63 performs the first operation, that is, when the first vibration signal Vm is output from the switch 55, the calculation section 64 performs the same operation as that of the first calculation section 34 of the first embodiment to generate and output the first detection signal Dm.

[0088] In addition, when the control section 63 performs the second operation, that is, when the second vibration signal Vc is output from the switch 55, the calculation section 64 performs the same operation as that of the second calculation section 44 of the first embodiment to generate and output the second detection signal Dc.

[0089] Therefore, when the selection signal received by the switch 55 is the first vibration signal Vm, the detection section 57 outputs the first detection signal Dm indicating the amplitude of the first vibration signal Vm. Furthermore, when the selection signal received by the switch 55 is the second vibration signal Vc, the detection section 57 outputs the second detection signal Dc indicating the amplitude of the second vibration signal Vc (ie, Coriolis force fc). [2-4. Process of the ratio calculation section]

[0090] The ratio calculation section 58 receives the first detection signal Dm and the second detection signal Dc from the detection section 57 and calculates a ratio of a value of the second detection signal Dc to a value of the first detection signal Dm, ie, Dc / Dm, as the ratio of the Coriolis force to the driving vibration velocity. The ratio calculation section 58 outputs the calculated ratio as the angular velocity detection result Dso. [2-5. Advantageous Effects of the Second Embodiment]

[0091] According to the second embodiment, advantageous effects similar to those of the first embodiment can also be provided. In addition, compared to the first embodiment, one of the two detection sections can be removed. Thus, the gyro sensor device can be further reduced in size. In the second embodiment, the switch 55 corresponds to a switch section. (3. Third Embodiment)[3-1. Configuration]

[0092] As in Fig. 6, a gyro sensor device 71 of the third embodiment differs from the gyro sensor device of the first embodiment in that a servo control circuit 75 is provided instead of the second detecting section 22.

[0093] The servo control circuit 75 performs servo control for the element 3 to generate the amount of displacement of the element 3 in the direction of the Coriolis force fc from zero, and outputs a digital signal indicative of the controlled variable of the servo control as a second detection signal Dc. Since the controlled variable of the servo control is proportional to the Coriolis force fc, the second detection signal Dc output from the servo control circuit 75 is a signal indicative of the Coriolis force fc. Such a servo control circuit is disclosed, for example, in JP 2011-137777 A and JP 2015-52484 A.

[0094] For example, the servo control circuit 75 may be configured to output a digital signal obtained by multiplying the controlled variable of the servo controller by a predetermined constant as the second detection signal Dc. [3-2. Advantageous effects of the third embodiment]

[0095] Also, according to the third embodiment, the advantageous effects (1a) to (1c) similar to those of the first embodiment can be provided. Additionally, in the third embodiment, the servo control circuit 75 corresponds to a second section and can also provide the advantageous effects described in (1d). Regarding the first detection section 21, the advantageous effects (1e) and (1f) can be obtained as described in the first embodiment. [Alternative embodiments](Alternative embodiment 1)

[0096] For example, in the first embodiment, the first pulse delay circuit 31 of the first detection section 21 may be a ring pulse delay circuit in which the pulse Pa circulates. In this case, for example, the first-stage delay unit 35 may be an AND gate circuit, and one of the input terminals of the AND gate circuit may be an input terminal for the pulse Pa. In addition, the other of the input terminals of the AND gate circuit may be connected to an output terminal of the last-stage delay unit 35.

[0097] Then, if the first pulse delay circuit 31 is a ring pulse delay circuit, a counter for counting the number of circulations of a pulse may be provided in the ring pulse delay circuit, and a data output circuit described later may be provided instead of the first pulse position detecting circuit 32.

[0098] The data output circuit detects a delay pulse group of the ring pulse delay circuit and counts a count value of the counter as input information every time the clock CKa rises. The data output circuit then outputs a digital signal indicating the number of delay units 35 that the pulse Pa has passed through from the start time of the pulse Pa based on the detected input information.

[0099] Note that a circuit including the ring pulse delay circuit, the counter, and the above-described data output circuit is referred to as a time A / D conversion circuit and is disclosed, for example, in JP 2005-102129 A (or DE 10 2004 041 558 A1) and JP H05-259 907 A (or DE 693 20 853 T2). Additionally, JP 2005-102129 A (or DE 10 2004 041 558 A1) discloses a configuration including a latch, an encoder, and a self-hold circuit as the configuration of the data output circuit.

[0100] That is, the first detection section 21 may be configured using a time-to-time A / D conversion circuit with a ring pulse delay circuit. Similarly, the second detection section 22 of the first embodiment, the detection section 57 of the second embodiment, and the first detection section 21 of the third embodiment may each be configured using a time-to-time A / D conversion circuit with a ring pulse delay circuit. (Alternative embodiment 2)

[0101] The delay units 35 configuring a pulse delay circuit may be configured using gate circuits other than the inverter gate circuits 36, for example, a gate circuit used in digital circuits, such as a NAND gate circuit, a NOR gate circuit, an AND gate circuit, and an OR gate circuit. Alternatively, the delay units 35 may be configured using delay elements used in an analog circuit. (Alternative embodiment 3)

[0102] Although the ratio calculating sections 23 and 58 are configured to calculate the above-described ratio by digital signal processing, the ratio calculating sections 23 and 58 may be configured to calculate the ratio by analog signal processing. (Alternative embodiment 4)

[0103] The first detection section 21 may include an A / D conversion circuit without using the pulse delay circuit to output the first detection signal Dm using the A / D conversion circuit. This configuration can be applied to the second detection section 22 and the detection section 57. (Other)

[0104] A plurality of functions of a component of the above-described embodiments may be provided by a plurality of components, or a function of a component may be provided by a plurality of components. A plurality of functions of a plurality of components may be provided by one component. A function provided by a plurality of components may be provided by one component. Part of the configurations of the above-described embodiments may be omitted. At least part of the configuration of one embodiment may be added to or omitted from the configuration of another embodiment.In addition to the gyro sensor device described above, various embodiments may be provided, such as a system having the gyro sensor device as a component, a program that enables a computer to function as the gyro sensor device, a non-transitory computer-readable recording medium such as a semiconductor memory that stores the program, and a method for processing a gyro sensor signal.

[0105] An aspect of the previously described embodiments is summarized below.

[0106] As one aspect of the embodiment, a gyro sensor device is provided which has a control section (5) and a processing unit (11, 53, 73).

[0107] The drive section (5) supplies a drive signal which serves to vibrate a sensor element (3) of a vibration-type gyro sensor in the drive axis direction to the sensor element.

[0108] The processing unit receives a first vibration signal and a second vibration signal. The first vibration signal has an amplitude proportional to a drive vibration amplitude, which is a vibration amplitude in the drive axis direction of the sensor element. The second vibration signal has an amplitude proportional to the Coriolis force generated in the sensor element due to an angular velocity of the sensor element. The processing unit calculates a ratio of the Coriolis force to the drive vibration amplitude based on the first vibration signal and the second vibration signal and outputs a calculation result as a result of detecting the angular velocity of the sensor element.

[0109] According to the gyro sensor device, even if the driving vibration amplitude changes due to temperature changes, in other words, even if the driving vibration speed changes, a detection result of an angular velocity can be obtained with high accuracy without performing feedback control to make the driving vibration amplitude constant. That is, if the driving vibration amplitude changes due to temperature changes, the generated Coriolis force changes. However, if the angular velocity does not change, since a ratio of the Coriolis force to the driving vibration amplitude is used, the detection result of the angular velocity calculated by the processing unit is not changed.

[0110] Therefore, a decrease in dimensioning can be achieved because a feedback control circuit is not required and high accuracy can be achieved, by which an angular velocity can be detected with high accuracy regardless of the temperature change.

[0111] In addition, even if a resonance frequency of the sensor element changes due to temperature changes or the like and the driving vibration speed changes, the ratio of the Coriolis force to the driving vibration amplitude, i.e., the detection result of the angular velocity calculated by the processing unit, does not change, resulting in a change in the driving vibration amplitude if the angular velocity is not changed. Therefore, a variation in the detection sensitivity can also be corrected according to the change in a resonance frequency of the sensor element.

[0112] Furthermore, the maximum drive vibration amplitude of the sensor element can be used. This allows angular velocity to be measured with high sensitivity.

Claims

[1] Gyro sensor device (51) with a drive section (5) which supplies a drive signal (Vd) for vibrating a sensor element (3) of a vibration-type gyro sensor in a drive axis direction to the sensor element (3); and a processing unit (53) receiving a first vibration signal (Vm) having an amplitude proportional to a drive vibration amplitude, which is a vibration amplitude in the drive axis direction of the sensor element (3), and a second vibration signal (Vc) having an amplitude proportional to the Coriolis force (fc) generated in the sensor element (3) due to an angular velocity of the sensor element (3), wherein the processing unit (53) comprises: a switch section (55) controlled by a control section (63) at each predetermined period of the first vibration signal (Vm) to alternately switch between the first vibration signal (Vm) and the second vibration signal (Vc) at each predetermined period of the first vibration signal (Vm), and to select and output one of the first vibration signal (Vm) and the second vibration signal (Vc) as a selection signal; a detection section (57) having the control section (63) and configured to receive the selection signal from the switch section (55), output a first detection signal (Dm) indicative of an amplitude of the first vibration signal (Vm) when the selection signal is the first vibration signal (Vm), and output a second detection signal (Dc) indicative of an amplitude of the second vibration signal (Vc) when the selection signal is the second vibration signal (Vc); and a ratio calculation section (58) configured to calculate a ratio of a value of the second detection signal (Dc) to a value of the first detection signal (Dm) as a ratio of the Coriolis force (fc) to the drive vibration amplitude, and output the calculated ratio as a result of the detection (Dso) of the angular velocity of the sensor element (3). [2] The gyro sensor device (51) according to claim 1, wherein the detection section (57) comprises a pulse delay circuit (61) in which a plurality of delay units (35) are configured such that the speed at which a received pulse signal propagates to an output side increases in proportion to a voltage value of the selection signal from the switch section (55), are connected in series, and the detection section (57) is configured to output the first detection signal (Dm) and the second detection signal (Dc) using the pulse delay circuit (61). [3] The gyro sensor device (51) according to claim 2, wherein the detecting section (57) is configured to: when the selection signal from the switch section (55) is the first vibration signal (Vm), to output as the first detection signal (Dm) a digital signal indicative of a difference between the number of delay units (35) that the pulse signal has passed through in the pulse delay circuit (61) during a half period during which the first vibration signal (Vm) is greater than an oscillation mean voltage (Vzm) of the first vibration signal (Vm) and the number of delay units (35) that the pulse signal has passed through in the pulse delay circuit (61) during a half period during which the first vibration signal (Vm) is less than an oscillation mean voltage (Vzm) of the first vibration signal (Vm), and when the selection signal from the switch section (55) is the second vibration signal (Vc), outputting as the second detection signal (Dc) a digital signal indicative of a difference between the number of delay units (35) that the pulse signal has passed through in the pulse delay circuit (61) during a half period during which the second vibration signal (Vc) is greater than an oscillation center voltage (Vzm) of the second vibration signal (Vc) and the number of delay units (35) that the pulse signal has passed through in the pulse delay circuit (61) during a half period during which the second vibration signal (Vc) is less than an oscillation center voltage (Vzm) of the second vibration signal (Vc).

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