JP2006329637A - Angular velocity detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angular velocity detector capable of enhancing detection accuracy of vibration control for a vibration object, by reducing dispersion in a cut-off frequency of a filter used in self-excited oscillation for resonance-vibrating the vibration object. <P>SOLUTION: This angular velocity detector includes the vibration object 102 displaced with Coriolis force generated by applying an angular velocity under a vibrated condition, an IV converter 3 for outputting a detection signal indicating a displacement amount of the vibration object 102, gm-C filters 4, 52 for filtering a wave based on the detection signal, a drive control circuit 7 for generating a driving signal Sd with a phase shifted by 90° from a vibration phase of the vibration object 102, based on the signal wave-filtered by the gm-C filters 4, 52, and a driving electrode 103 for vibrating the vibration object 102 in response to the driving signal Sd. The cut-off frequencies are varied in response to a reference signal output from a reference oscillation source 13, in the gm-C filters 4, 52. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an angular velocity detection device for measuring an angular velocity by measuring a Coriolis force when an angular velocity due to an external force is applied to a vibrating body applying a prescribed vibration.

  In recent years, angular velocity detection devices using gyro sensors have been used in suspension and airbag control devices in automobiles, inertial navigation systems in aircraft, camera shake correction devices for cameras, and the like. As this type of angular velocity detection device, there is known a vibration type gyro sensor that measures angular velocity by measuring Coriolis force when an angular velocity due to an external force acts on a mass body that is applying a prescribed vibration (for example, a patent) Reference 1 and non-patent reference 1).

  FIG. 9 is a conceptual diagram for explaining the configuration of the gyro sensor according to the background art. A gyro sensor 101 shown in FIG. 9 has one side of the vibrating body 102 when the X axis is parallel to one side of the vibrating body 102 as shown in FIG. And a driving electrode 103 arranged opposite to each other in the X-axis direction and detection electrodes 105 and 106 arranged opposite to each other with the vibrating body 102 sandwiched in the Y-axis direction orthogonal to the X-axis. ing. The drive electrode 103 and the detection electrodes 105 and 106 are arranged to face each other with a distance from the vibrating body 102, and electrostatic capacitances C 103, C 105, and C 106 are formed between the driving electrode 103 and the detection electrodes 105 and 106.

  FIG. 10 is an explanatory diagram for explaining the operation of the gyro sensor 101. In the gyro sensor 101 shown in FIG. 9, when an AC voltage is applied to the driving electrode 103, a periodic electrostatic force is generated between the vibrating body 102 and the driving electrode 103, and the vibrating body 102 extends along the X-axis direction. Vibrate. In this state, when an angular velocity R is applied to the gyro sensor 101 about an axis perpendicular to the paper surface, a Coriolis force is generated in the Y-axis direction, and the vibrating body 102 is displaced in the Y-axis direction according to the Coriolis force. When the vibrating body 102 is displaced in the Y-axis direction, the capacitances C105 and C106 between the vibrating body 102 and the detection electrodes 105 and 106 change.

  Therefore, the capacitances C105 and C106 change according to the angular velocity applied to the gyro sensor 101 if the vibration velocity of the vibrating body 102 is constant. Therefore, the angular velocity detection apparatus using the gyro sensor 101 detects the angular velocity applied to the gyro sensor 101 by detecting the capacitance change of the capacitances C105 and C106.

  Here, since the displacement in the Y-axis direction due to the Coriolis force generated by the angular velocity is proportional to the vibration velocity in the X-axis direction, in order to detect the angular velocity with high accuracy, the vibration velocity of the vibrating body 102 is increased to a constant and constant velocity. It is necessary to keep on. For this purpose, it is desirable to vibrate the vibrating body 102 at a specific resonance frequency. Further, when the vibrating body 102 is in a resonance state, a signal whose phase is delayed by 90 degrees with respect to the driving voltage signal applied to the driving electrode 103 is a detection signal indicating the mechanical displacement of the vibrating body 102 in the X-axis direction. It is known that it can be obtained as

  Therefore, conventionally, a detection signal indicating the mechanical displacement of the vibrating body 102 in the X-axis direction when the vibrating body 102 is vibrated is phase-shifted by 90 degrees and supplied to the driving electrode 103 as a driving voltage. The vibrating body 102 is resonated at the resonance frequency.

  FIG. 11 is a block diagram showing an electrical configuration of the angular velocity detection device according to the background art. In FIG. 11, the gyro sensor 101 is shown by an equivalent circuit. An angular velocity detection device 100 shown in FIG. 11 includes a gyro sensor 101, a carrier generation circuit 111, an IV converter 112, a bandpass filter (hereinafter abbreviated as BPF) 113, a first synchronous detection circuit 115, and a second synchronous detection circuit 116. A drive control circuit 117, an amplifier 118, an inverter 119, and phase shifters 120 and 121.

  The carrier generation circuit 111 supplies a carrier signal having a predetermined frequency for capacitance detection, for example, a frequency of 100 kHz, to the capacitance C105 and also supplies the capacitance C106 via the inverter 119. That is, the carrier signals supplied to the capacitances C105 and C106 are made to be 180 degrees out of phase with each other.

  The IV converter 112 converts the current signal detected from the vibrating body 102 into a voltage signal and outputs the voltage signal to the BPF 113. In this case, the capacitances C105 and C106 change when the vibrating body 102 is displaced in the Y-axis direction, and the capacitance C103 changes when the vibrating body 102 is displaced in the X-axis direction. When the capacitances C105, C106, and C103 change, the current flowing from the vibrating body 102 to the IV converter 112 changes. Therefore, the output signal of the IV converter 112 includes a displacement amount of the vibrating body 102 in the Y-axis direction. That is, a signal component indicating the angular velocity applied to the vibrating body 102, a signal component indicating a mechanical displacement in the X-axis direction due to the resonant vibration of the vibrating body 102, and the carrier generation circuit 111 via the capacitances C105 and C106. The signal component of the carrier signal supplied to the vibrating body 102 is included.

  The BPF 113 removes unnecessary frequency components such as noise from the output signal of the IV converter 112. The phase shifter 120 shifts the phase of the carrier signal by 90 degrees and outputs it to the first synchronous detection circuit 115.

  The first synchronous detection circuit 115 removes the carrier signal component from the output signal of the BPF 113 by synchronously detecting the output signal of the BPF 113 based on the signal output from the phase shifter 120, and the second synchronous detection circuit 116, the drive control circuit 117, and the phase shifter 121. In this case, the output signal of the first synchronous detection circuit 115 includes a signal component indicating the change in the capacitances C105 and C106, that is, the displacement amount of the vibrating body 102 in the Y-axis direction, and the X axis due to the resonance vibration of the vibrating body 102. And a signal component indicating a mechanical displacement in the direction.

  The drive control circuit 117 is a circuit that causes the vibration body 102 to resonate and vibrate by supplying an AC voltage having a resonance frequency in the vibration body 102 to the capacitance C103 via the amplifier 118 as the drive signal Sd. The phase of the drive signal Sd is adjusted so that the phase of the detected signal and the phase of the drive signal Sd are shifted by 90 degrees, and the vibrator 102 is resonantly oscillated by self-excited oscillation. For example, when the phase of the detection signal from the IV converter 112 is delayed by 5 degrees due to the IV converter 112, the BPF 113, and the first synchronous detection circuit 115, the drive control circuit 117 is output from the first synchronous detection circuit 115. By delaying the phase of the signal component indicating the mechanical displacement in the X-axis direction in the received signal by 85 degrees, the phase of the signal detected by the IV converter 112 and the phase of the drive signal Sd are shifted by 90 degrees.

  Thereby, a detection signal indicating the mechanical displacement of the vibrating body 102 in the X-axis direction is phase-shifted by 90 degrees and supplied to the driving electrode 103 as the driving signal Sd, and the vibrating body 102 is self-oscillated at the resonance frequency. The vibration speed of the vibrating body 102 is increased and made constant.

The output signal of the first synchronous detection circuit 115 is shifted by 90 degrees by the phase shifter 121 in a state in which the vibrator 102 is resonantly vibrated in this way, and the first synchronous detection circuit 115 is shifted by the second synchronous detection circuit 116. Is detected based on the output signal of the phase shifter 121, the signal component indicating the mechanical displacement in the X-axis direction of the vibrating body 102 is removed from the output signal of the first synchronous detection circuit 115, A signal component indicating the amount of displacement of the vibrating body 102 in the Y-axis direction, that is, an angular velocity signal Sout indicating the angular velocity applied to the vibrating body 102 is output.
JP-A-8-159776 `` M. Nagao, H. Watanabe, E. Nakatani, K. Shirai, K. Aoyama, and M. Hashimoto: A Silicon Micromachined Gyroscope and Accelerometer for Vehicle Stability Control System, SAE Paper 2004-01-1113 "

  By the way, in the angular velocity detection device configured as described above, the drive control circuit 117 causes the output signal of the first synchronous detection circuit 115 to be the phase delay of the signals from the IV converter 112, the BPF 113, and the first synchronous detection circuit 115. And the phase of the output signal of the first synchronous detection circuit 115 is shifted so that the phase of the signal detected by the IV converter 112 and the phase of the drive signal Sd are shifted by 90 degrees to generate the drive signal Sd. . In this case, the phase delay in the BPF 113 depends on the cutoff frequency of the BPF 113. For this reason, when the cutoff frequency of the BPF 113 varies due to characteristic variations of the BPF 113, the phase delay due to the BPF 113 also varies and fluctuates.

  In addition, since the first synchronous detection circuit 115 includes a multiplier and a low-pass filter, the phase delay in the first synchronous detection circuit 115 also depends on the cutoff frequency of the low-pass filter. For this reason, if the cutoff frequency of the low-pass filter varies due to characteristic variations of the low-pass filter, the phase delay caused by the first synchronous detection circuit 115 also varies and fluctuates.

  As described above, when the cutoff frequency of a filter such as a low-pass filter used in the BPF 113 or the first synchronous detection circuit 115 varies, the phase delay in each part varies, and the phase of the signal detected by the IV converter 112 and the drive signal Sd. As a result, the vibration frequency of the vibrating body 102 is deviated from the resonance frequency.

  In particular, there is a case where the Q value of the resonance vibration of the vibrating body 102 is set to a high value exceeding 1000. In such a case, for example, the phase delay of the drive signal Sd changes once, thereby causing vibration. The vibration amplitude of the body 102 may change by 50% or more. Since the Coriolis force acting on the vibration body 102 depends on the vibration amplitude of the vibration body 102, the phase delay error in the drive signal Sd has a great influence on the detected angular velocity.

  The present invention has been made in view of such problems, and controls vibration of a vibrating body by reducing variations in the cut-off frequency of a filter used for self-excited oscillation for resonant vibration of the vibrating body. An object of the present invention is to provide an angular velocity detection device capable of improving the accuracy of the above.

  In order to achieve the above object, an angular velocity detection device according to the present invention detects a vibrating body that is displaced by a Coriolis force generated by applying an angular velocity in a vibrating state, and an amount of displacement of the vibrating body. A detection unit that outputs a detection signal indicating the detected displacement amount, a filter unit that performs filtering based on the detection signal output from the detection unit, and a signal that is filtered by the filter unit, A drive signal generation unit that generates a drive signal that is 90 degrees out of phase with a vibration phase; and a drive unit that vibrates the vibration body in accordance with the drive signal generated by the drive signal generation unit, the filter The section is characterized in that the cut-off frequency changes according to a reference signal having a predetermined frequency.

  In the above-described angular velocity detection device, the filter unit includes a tuner unit that outputs a control signal corresponding to the frequency of the reference signal, and a gm element whose amplification factor changes according to the control signal output from the tuner unit. And a capacitor that filters the output of the gm element.

  In the above-described angular velocity detection device, the filter unit is a switched capacitor filter including a switched capacitor circuit in which a pseudo resistance value changes according to the frequency of the reference signal.

  Further, in the above-described angular velocity detection device, by applying a carrier signal output unit that outputs a carrier signal having a predetermined frequency set in advance, and a carrier signal output from the carrier signal output unit to the vibrating body, A carrier signal applying unit that superimposes a signal component corresponding to the displacement amount of the vibrating body on the carrier signal, and the detection unit detects the carrier signal on which the signal component is superimposed as the detection signal. It is a feature.

  In the above-described angular velocity detection device, a multiplication unit that multiplies the detection signal detected by the detection unit and a carrier signal output from the carrier signal output unit, and a low-pass filter that filters the signal multiplied by the multiplication unit And the low-pass filter is the filter unit.

  In the above-described angular velocity detection device, a carrier signal output from the carrier signal output unit is used as the reference signal.

  In the above-described angular velocity detection device, the drive signal generated by the drive signal generation unit is used as the reference signal.

  The angular velocity detection device further includes an amplifying unit that amplifies the carrier signal output from the carrier signal output unit to the carrier signal applying unit according to the signal level of the detection signal output from the detection unit. It is characterized by that.

  In the angular velocity detection device having such a configuration, when an angular velocity is applied in a state where the vibrating body is vibrated, the vibrating body is displaced by Coriolis force, and a detection signal indicating the amount of displacement is output from the detection unit to the filter unit, and a drive signal Based on the detection signal filtered by the filter unit, the generation unit generates a drive signal that is 90 degrees out of phase with the vibration phase of the vibration body so as to cause the vibration body to resonate and vibrate according to the drive signal. Is vibrated. And since the cutoff frequency of the filter unit is set according to the reference signal having a predetermined frequency, the variation in the cutoff frequency of the filter unit is reduced, and the phase delay of the signal in the filter unit is reduced, The accuracy of vibration control of the vibrating body can be improved.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a block diagram showing an example of the configuration of the angular velocity detection device according to the first embodiment of the present invention. 1 includes a carrier generation circuit 2 (carrier signal output unit), an IV converter 3 (detection unit), a gm-C filter 4 (filter unit), a first synchronous detection circuit 5, and a second synchronization. A detection circuit 6, a drive control circuit 7 (drive signal generation unit), amplifiers 8 and 9, an inverter 10, phase shifters 11 and 12, a reference oscillation source 13, a frequency divider 14, and a gyro sensor 101 are provided.

  In FIG. 1, the gyro sensor 101 is shown by an equivalent circuit. Since the configuration of the gyro sensor 101 is the same as that of the gyro sensor 101 shown in FIGS. 9 and 11, the description thereof is omitted. Further, the drive electrode 103 in the gyro sensor 101 shown in FIG. 9 corresponds to an example of a drive unit in claims, and the detection electrodes 105 and 106 correspond to an example of a carrier signal applying unit.

  The carrier generation circuit 2 supplies a carrier signal having a predetermined frequency for capacitance detection, for example, a frequency of 100 kHz, to the capacitance C105 and also supplies the capacitance C106 via the inverter 10. That is, the carrier signals supplied to the capacitances C105 and C106 are made to be 180 degrees out of phase with each other. The carrier signal output from the carrier generation circuit 2 is phase-shifted 90 degrees by the phase shifter 11 and output to the first synchronous detection circuit 5.

  The IV converter 3 converts the current signal S102, which is a detection signal indicating the displacement of the vibrating body 102, detected from the vibrating body 102 into a voltage signal, and outputs the voltage signal to the BPF 41 in the gm-C filter 4 as a signal S3. In this case, the capacitances C105 and C106 change when the vibrating body 102 is displaced in the Y-axis direction, and the capacitance C103 changes when the vibrating body 102 is displaced in the X-axis direction. When the capacitances C105, C106, and C103 change, the current flowing from the vibrating body 102 to the IV converter 3 changes. Therefore, the output signal S3 of the IV converter 3 includes the displacement of the vibrating body 102 in the Y-axis direction. A signal component indicating an amount, that is, an angular velocity applied to the vibrating body 102, a signal component indicating a mechanical displacement in the X-axis direction due to resonance vibration of the vibrating body 102, and capacitances C105 and C106 from the carrier generating circuit 2. The signal component of the carrier signal supplied to the vibrating body 102 is included.

  The reference oscillation source 13 is an oscillation circuit that outputs a reference signal CLK1 serving as a reference for determining the cutoff frequency of the gm-C filter 4 and the gm-C filter 52 to the gm-C filter 4 and the frequency divider 14. For example, a high-precision crystal oscillation circuit is used. The frequency divider 14 divides the reference signal CLK1 and outputs it to the gm-C filter 52 as the reference signal CLK2. For example, if the frequency of the carrier signal output from the carrier generation circuit 2 is 100 kHz and the resonant vibration frequency of the vibrator 102 is 2 kHz, the frequency division ratio of the frequency divider 14 is set to approximately 1/50. .

  The gm-C filter 4 is a filter unit whose cutoff frequency changes according to the reference signal output from the reference oscillation source 13, and includes a band pass filter (hereinafter abbreviated as BPF) 41 and a tuner unit 42. ing.

  FIG. 2 is a block diagram illustrating an example of the configuration of the gm-C filter 4. The BPF 41 shown in FIG. 2 is configured using gm elements 43, 44, and 45, an operational amplifier 46, and capacitors C1 and C2. The gm elements 43, 44, and 45 are elements that amplify a signal input between the + input terminal and the − input terminal with an amplification factor gm corresponding to a predetermined control signal and output the signal, for example, using a transistor. For example, a gm element described in “EXTRA serise No. 30 CMOS analog circuit design technology” (published by Trikeps Co., Ltd. and supervised by Atsushi Iwata) can be used.

  In the BPF 41, the output signal S3 of the IV converter 3 is connected to the + input terminal of the gm element 43, and the output terminal of the gm element 43 is connected to the − input terminal of the gm element 44 and the + input terminal of the operational amplifier 46. ing. The output terminal of the gm element 43 is connected to the ground via the capacitor C1. The + input terminal of the gm element 44 is connected to the ground, and the output terminal of the gm element 44 is connected to the − input terminal of the gm element 45.

  The + input terminal of the gm element 45 is connected to the ground, and the output terminal of the gm element 45 is connected to the − input terminal of the gm element 43 and is connected to the ground via the capacitor C2. The output terminal of the operational amplifier 46 is connected to the negative input terminal of the operational amplifier 46, and the output signal of the operational amplifier 46 is output to the first synchronous detection circuit 5 as the output signal S 4 of the gm-C filter 4.

  The tuner unit 42 outputs a control signal VC1 that controls the amplification factor of the gm elements 43, 44, and 45 in accordance with the reference signal CLK1 output from the reference oscillation source 13, and sets the amplification factor of the gm elements 43, 44, and 45. By setting, the cutoff frequency of the BPF 41 is set to a frequency corresponding to the reference signal CLK1. As the tuner unit 42, for example, “IEEE JOURNAL OF SOLID-STATE CIRCUITS VOL23, NO.3, JUNE 1988 pp.754-755 A 4 MHz CMOS ContinuousTime FilterNITICT ) "Can be used.

  Thereby, since the cut-off frequency of the gm-C filter 4 is set according to the reference signal CLK1 output from the reference oscillation source 13, the cut-off frequency variation due to the filter characteristic variation can be reduced. Moreover, as a result of reducing the variation in the cut-off frequency, the variation in the signal phase delay in the gm-C filter 4 can be reduced.

  FIG. 3 is an explanatory diagram illustrating an example of the frequency characteristics of the BPF 41. The signal S 3 output from the IV converter 3 is a signal obtained by modulating the carrier signal output from the carrier generation circuit 2, for example, a frequency signal of 100 kHz, with the vibration frequency of the vibrating body 102. Therefore, for example, if the vibrating body 102 vibrates at 2 kHz, the signal S3 output from the IV converter 3 has a frequency of the carrier signal output from the carrier generation circuit 2, for example, 100 kHz, as shown in FIG. A frequency component and a frequency component indicating the mechanical vibration of the vibrating body 102 (hereinafter referred to as a mechanical vibration component) are included. The mechanical vibration component is a frequency component obtained by adding the vibration frequency of the vibrating body 102 to the frequency of the carrier signal, for example, a frequency signal of 102 kHz, and a frequency component obtained by subtracting the vibration frequency of the vibrating body 102 from the frequency of the carrier signal, For example, the frequency signal is 98 kHz.

  Then, the BPF 41 outputs the frequency component of the carrier signal in the signal S3 and the mechanical vibration component to the first synchronous detection circuit 5 as the signal S4.

  The first synchronous detection circuit 5 includes a multiplier 51 (multiplication unit) and a gm-C filter 52 (filter unit). The gm-C filter 52 includes a low-pass filter (hereinafter abbreviated as LPF) 53 and a tuner unit 54.

  The multiplier 51 multiplies the signal output from the phase shifter 11, that is, the signal obtained by phase shifting the carrier signal by 90 degrees, and the signal S4, and outputs the signal S51 to the gm-C filter 52.

  FIG. 4 is a block diagram illustrating an example of the configuration of the gm-C filter 52. The LPF 53 shown in FIG. 4 includes gm elements 531, 532, and 533 and capacitors C3 and C4. The gm elements 531, 532, and 533 are gm elements configured similarly to the gm elements 43, 44, and 45.

  In the LPF 53, the output signal S 51 of the multiplier 51 is input to the + input terminal of the gm element 531, and the output terminal of the gm element 531 is connected to the − input terminal of the gm element 532. The output terminal of the gm element 531 is connected to the ground via the capacitor C3. The + input terminal of the gm element 532 is connected to the ground, and the output terminal of the gm element 532 is connected to the − input terminal of the gm element 533.

  The + input terminal of the gm element 533 is connected to the ground, and the output terminal of the gm element 533 is connected to the − input terminal of the gm element 531 and is connected to the ground via the capacitor C4. Further, the output signal of the gm element 533 is output to the second synchronous detection circuit 6, the drive control circuit 7, and the phase shifter 12 as the output signal S5 of the gm-C filter 52.

  The tuner unit 54 is configured in the same manner as the tuner unit 42, and outputs a control signal VC2 that controls the amplification factor of the gm elements 531, 532, and 533 according to the reference signal CLK2 output from the frequency divider 14. By setting the amplification factors of the gm elements 531, 532, and 533, the cutoff frequency of the LPF 53 is set to a frequency corresponding to the reference signal CLK2.

  Thereby, since the cut-off frequency of the gm-C filter 52 is set according to the reference signal CLK2, variations in the cut-off frequency due to variations in filter characteristics can be reduced. Moreover, as a result of reducing the variation in the cutoff frequency, the variation in the signal phase delay in the gm-C filter 52 can be reduced.

  The drive control circuit 7 adjusts the phase of the signal S <b> 5 to a phase shifted by 90 degrees from the phase of the mechanical vibration of the vibrating body 102, and outputs the signal as a drive signal Sd to the capacitance C <b> 103 via the amplifier 8. Specifically, in the signal S102 obtained from the vibrating body 102, the mechanical vibration of the vibrating body 102 is represented by a current signal as a mechanical vibration component modulated by the carrier signal. In this case, because of the capacitances C105 and C106, the phase of the current is advanced by 90 degrees, and therefore the mechanical vibration component included in the signal S102 is advanced by 90 degrees from the actual mechanical vibration phase of the vibrating body 102. It is a phase.

  Therefore, the drive control circuit 7 has a phase shift amount set in advance so as to cancel the phase delay in the IV converter 3, the gm-C filter 4, and the first synchronous detection circuit 5. As a result, the phase of the drive signal Sd can be shifted to a phase shifted by 90 degrees from the phase of the mechanical vibration of the vibrating body 102.

  The second synchronous detection circuit 6 is a synchronous detection circuit that synchronously detects the signal S5 based on the output signal from the phase shifter 12, and extracts a signal component indicating an angular velocity by removing a mechanical vibration component from the signal S5, and an amplifier 9 is output to the outside as an angular velocity signal Sout.

  Next, the operation of the angular velocity detection device 1 configured as described above will be described. First, when the drive signal Sd is supplied from the drive control circuit 7 to the electrostatic capacitance C103 (drive electrode 103) via the amplifier 8, the vibrating body 102 vibrates. Next, when a carrier signal is supplied from the carrier generation circuit 2 to the vibrating body 102 via the electrostatic capacity C105, the inverter 10 and the electrostatic capacity C106, and further acceleration is applied to the vibrating body 102, IV conversion is performed. The device 3 obtains a signal S102 including a signal component indicating an angular velocity applied from the vibrating body 102 to the vibrating body 102, a mechanical vibration component, and a signal component of the carrier signal, and the signal S102 is converted into a voltage. Is output to the gm-C filter 4 as a signal S3.

  Then, the gm-C filter 4 removes a frequency component such as unnecessary noise other than the signal component indicating the angular velocity, the mechanical vibration component, and the signal component of the carrier signal, and outputs the signal S4 to the first synchronous detection circuit 5. Is done.

  In this case, since the cut-off frequency of the gm-C filter 4 is set according to the reference signal CLK1 output from the reference oscillation source 13, variation in the cut-off frequency due to variation in filter characteristics is reduced, and gm-C Variation in the phase delay of the signal in the filter 4 is reduced.

  Next, the first synchronous detection circuit 5 synchronously detects the signal S4 based on the output signal from the phase shifter 11, the signal component of the carrier signal is removed from the signal S4, and the second synchronous detection circuit 6, It is output to the drive control circuit 7 and the phase shifter 12. In this case, the signal S5 includes a signal component indicating an angular velocity and a mechanical vibration component.

  Next, the signal S5 is phase-shifted by a preset phase shift amount by the drive control circuit 7, and the drive signal Sd is shifted by 90 degrees from the phase of the mechanical vibration of the vibrating body 102 so that the electrostatic capacitance The vibration body 102 is resonated and oscillated at the resonance frequency.

  In this case, a signal path used for self-excited oscillation for resonantly vibrating the vibrating body 102, that is, from the vibrating body 102 to the IV converter 3, the gm-C filter 4, the first synchronous detection circuit 5, the drive control circuit 7, and Variations in the filter cut-off frequency between the gm-C filter 4 and the gm-C filter 52, which are filters on the signal path from the amplifier 8 to the capacitance C103, are affected by variations in component characteristics and temperature characteristics. Therefore, the variation of the signal phase delay between the gm-C filter 4 and the gm-C filter 52 is reduced, the phase delay becomes constant, and the phase shift amount set in advance in the drive control circuit 7 is reduced. This improves the accuracy of vibration control of the vibrating body so that the drive signal Sd is shifted by 90 degrees from the phase of the mechanical vibration of the vibrating body 102 by the phase shift. Kill result, it is possible to improve the accuracy of the angular velocity signal Sout.

  In addition, although the example which comprises LPF53 in BPF41 and the 1st synchronous detection circuit 5 as a gm-C filter was shown, only one of BPF41 and the 1st synchronous detection circuit 5 is used as a gm-C filter. It may be configured. Alternatively, a configuration may be employed in which only one of the BPF 41 and the first synchronous detection circuit 5 is provided on a signal path used for self-excited oscillation for causing the vibrating body 102 to resonate and vibrate.

  Further, although the reference signal CLK1 output from the reference oscillation source 13 is divided by the frequency divider 14 to generate the reference signal CLK2, an oscillator that outputs the reference signal CLK2 instead of the frequency divider 14 is shown. It may be provided.

  Moreover, although the example which comprises LPF53 in BPF41 and the 1st synchronous detection circuit 5 as a gm-C filter was shown, the switched capacitor filter comprised by the switched capacitor circuit may be used instead of a gm-C filter. . FIG. 5 is an explanatory diagram showing an example in which the low-pass filter (gm-C filter 52) in the first synchronous detection circuit 5 is configured by a switched capacitor filter. FIG. 5A is an example of the configuration of the switched capacitor filter, and FIG. 5B is a conceptual diagram for explaining the operation of the switched capacitor filter.

  The switched capacitor filter shown in FIG. 5A includes a switch SW1 and capacitors C5 and C6. The switch SW1 includes connection terminals T1, T2, and T3, and is a changeover switch that switches the connection between the connection terminal T3 and the connection terminals T1 and T2 in accordance with the reference signal CLK2. The connection terminal T3 is connected to the ground via the capacitor C6, the output signal S51 of the multiplier 51 is received by the connection terminal T1, and the connection terminal T2 is connected to the ground via the capacitor C5. Furthermore, the terminal voltage of the capacitor C5 is output as the signal S5 to the second synchronous detection circuit 6, the drive control circuit 7, and the phase shifter 12.

  In this case, a switched capacitor circuit 55 is configured by the switch SW1 and the capacitor C6. The switched capacitor circuit 55 can be regarded as a variable resistor whose resistance value changes in accordance with the switching frequency of the switch SW1 in a pseudo manner, as shown in FIG. 5B. Accordingly, the switched capacitor filter shown in FIG. 5A functions as a low-pass filter whose cutoff frequency changes according to the reference signal CLK2.

  Similarly, the BPF 41 can be a bandpass filter using a switched capacitor filter.

(Second Embodiment)
Next, an angular velocity detection device according to the second embodiment of the present invention will be described. FIG. 6 is a block diagram showing an example of the configuration of the angular velocity detection device 1a according to the second embodiment of the present invention. The angular velocity detection device 1a shown in FIG. 6 does not include the reference oscillation source 13 as in the angular velocity detection device 1 shown in FIG. 1, and the carrier signal output from the carrier generation circuit 2 is separated from the tuner unit 42 as the reference signal CLK1. The difference is that the signal is input to the frequency divider 14. Other configurations and operations are the same as those of the angular velocity detection device 1 shown in FIG.

  Thereby, since it is not necessary to use the reference oscillation source 13, the circuit of the angular velocity detection device 1a can be simplified.

  Further, the amount of phase delay in the BPF 41 and the LPF 53 differs depending on the signal frequency passing through each filter. Therefore, if the frequency of the carrier signal output from the carrier generation circuit 2 varies while the cutoff frequency of the BPF 41 and the LPF 53 is constant, the phase delay amount in the BPF 41 and the LPF 53 varies. The accuracy of vibration control is reduced to a phase shifted by 90 degrees from the phase of mechanical vibration.

  However, in the angular velocity detection device 1a shown in FIG. 6, the frequency of the carrier signal output from the carrier generation circuit 2 changes due to, for example, temperature characteristics of the carrier generation circuit 2 and component variations, or the frequency of the carrier signal is designed. Even in the case of the above change, the cut-off frequencies of the BPF 41 and the LPF 53 are changed by the tuner units 42 and 54 according to the frequency of the carrier signals (reference signals CLK1 and CLK2). Thus, the cut-off frequency of the BPF 41 and the LPF 53 is changed, and the fluctuation of the phase delay amount in the BPF 41 and the LPF 53 can be reduced.

(Third embodiment)
Next, an angular velocity detection device according to the third embodiment of the present invention will be described. FIG. 7 is a block diagram showing an example of the configuration of an angular velocity detection device 1b according to the third embodiment of the present invention. The angular velocity detection device 1b shown in FIG. 7 is different from the angular velocity detection device 1a shown in FIG. 6 in that an amplitude adjustment circuit 15 is further provided. The amplitude adjustment circuit 15 is a carrier generation circuit according to the signal level of the output signal S5 of the first synchronous detection circuit 5 that is a signal reflecting the signal level of the signal S3 that is the detection signal output from the IV converter 3. 2 is an example of an amplifying unit that amplifies a carrier signal output from 2;

  The amplitude adjustment circuit 15 detects the peak voltage of the output signal S5 of the first synchronous detection circuit 5, and reduces the amplification factor of the carrier signal according to the increase or decrease of the peak voltage detected by the peak detection unit 16. An auto gain controller (hereinafter referred to as AGC) 17 is provided.

  Since other configurations and operations are the same as those of the angular velocity detection device 1a shown in FIG. 6, the description thereof will be omitted, and the characteristic operations of the angular velocity detection device 1b will be described below. In the gyro sensor 101, the impedances of the capacitances C105 and C106 increase and decrease according to the increase and decrease of the frequency of the carrier signal output from the carrier generation circuit 2. For example, when the frequency of the carrier signal increases, the impedances of the capacitances C105 and C106 decrease, the current in the signal S102 increases, and the signal amplitude of the signal S3 increases. As a result, the signals S4 and S5 obtained in the subsequent circuit And the signal level of the angular velocity signal Sout increases.

  Therefore, if the frequency of the carrier signal output from the carrier generation circuit 2 changes due to the influence of variation in characteristics of the carrier generation circuit 2 and temperature characteristics, the signal level of the angular velocity signal Sout is affected, and the detection accuracy of the angular velocity is reduced. There is a risk.

  Therefore, in the angular velocity detection device 1b shown in FIG. 7, for example, when the frequency of the carrier signal output from the carrier generation circuit 2 increases and the signal amplitude of the signal S5 output from the first synchronous detection circuit 5 increases, The peak voltage of S5 is detected by the peak detector 16, a signal indicating the peak voltage is output to the AGC 17, the amplification factor of the carrier signal by the AGC 17 is reduced, and the capacitance C105, the inverter 10 and the capacitance of the AGC 17 are reduced. The signal amplitude of the carrier signal supplied to the vibrating body 102 via C106 is reduced.

  When the signal amplitude of the carrier signal decreases, the increase in the signal amplitude of the signal S3 caused by the increase in the frequency of the carrier signal is canceled out, so that the change in the signal amplitude of the signal S3 due to the influence of the frequency change of the carrier signal is reduced. can do.

  Similarly, for example, when the frequency of the carrier signal output from the carrier generation circuit 2 decreases and the signal amplitude of the signal S5 output from the first synchronous detection circuit 5 decreases, the peak voltage of the signal S5 becomes the peak detector 16. A signal indicating the peak voltage is output to the AGC 17, and the amplification factor of the carrier signal by the AGC 17 is increased. From the AGC 17 to the vibrator 102 via the electrostatic capacity C 105, the inverter 10 and the electrostatic capacity C 106. The signal amplitude of the supplied carrier signal is increased.

  When the signal amplitude of the carrier signal is increased, the decrease in the signal amplitude of the signal S3 caused by the decrease in the frequency of the carrier signal is canceled out, so that the change in the signal amplitude of the signal S3 due to the influence of the frequency change of the carrier signal is reduced. can do.

(Fourth embodiment)
Next, an angular velocity detection device according to the fourth embodiment of the present invention will be described. FIG. 8 is a block diagram showing an example of the configuration of an angular velocity detection device 1c according to the fourth embodiment of the present invention. The angular velocity detection device 1c shown in FIG. 8 is different from the angular velocity detection device 1b shown in FIG. 7 in that a multiplier 18 is provided instead of the frequency divider 14. As the multiplier 18, for example, a multiplier circuit using a PLL (Phase-Locked Loop) circuit can be used.

  The multiplier 18 multiplies the drive signal Sd output from the drive control circuit 7 to generate the reference signal CLK 2, and the generated reference signal CLK 2 is supplied to the first synchronous detection circuit 5. In this case, for example, when the resonance frequency of the vibrator 102, that is, the frequency of the drive signal Sd is set to 2 kHz, the frequency of the carrier signal is 100 kHz, and the cutoff frequency of the LPF 53 is 8 kHz, the frequency magnification of the multiplier 18 is 4 Set to double.

  Since other configurations and operations are the same as those of the angular velocity detection device 1b shown in FIG. 7, the description thereof will be omitted, and the characteristic operations of the angular velocity detection device 1c will be described below. The resonance frequency of the vibrating body 102 in the gyro sensor 101 varies depending on the processing accuracy of the vibrating body 102 and the driving electrode 103, and in particular, the resonance frequency changes due to the variation of the capacitance C103. When the resonance frequency of the vibrating body 102 changes, the signal frequency of the mechanical vibration component included in the signal S4 output from the BPF 41 to the first synchronous detection circuit 5 changes.

  Then, the phase delay in the LPF 53 changes, and even if the drive control circuit 7 performs a phase shift of a preset shift amount on the signal S5 output from the LPF 53, the drive signal Sd and the machine of the vibrating body 102 There is a possibility that the phase of vibration does not shift by 90 degrees and the vibration control accuracy of the vibrating body is lowered.

  However, in the angular velocity detection device 1c shown in FIG. 8, when the resonance frequency of the vibrating body 102 changes, the frequency of the reference signal CLK2 is interlocked with the drive signal Sd, which is a signal having the same frequency as the resonance frequency, by the multiplier 18. The tuner unit 54 changes the cutoff frequency of the LPF 53 in accordance with the reference signal CLK2.

  As a result, the cutoff frequency of the LPF 53 can be changed in conjunction with the change of the resonance frequency in the vibrating body 102, and the change in the phase delay in the LPF 53 due to the influence of the resonance frequency can be reduced. As a result, the drive control circuit 7 The accuracy of vibration control of the vibrating body is improved by making the drive signal Sd a phase shifted by 90 degrees from the mechanical vibration phase of the vibrating body 102 by the phase shift of the preset phase shift amount in FIG. The accuracy of the signal Sout can be improved.

It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 1st Embodiment of this invention. It is a circuit diagram which shows an example of a structure of the gm-C filter shown in FIG. It is explanatory drawing which shows an example of the frequency characteristic of BPF shown in FIG. It is a circuit diagram which shows an example of a structure of the gm-C filter shown in FIG. It is explanatory drawing which shows an example at the time of comprising the low-pass filter (gm-C filter) in the 1st synchronous detection circuit shown in FIG. 1 by the switched capacitor filter. (A) is an example of a structure of a switched capacitor filter, (b) is a conceptual diagram for demonstrating operation | movement of a switched capacitor filter. It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 4th Embodiment of this invention. It is a conceptual diagram for demonstrating the structure of the gyro sensor which concerns on background art. It is explanatory drawing for demonstrating operation | movement of the gyro sensor shown in FIG. It is a block diagram which shows the electrical constitution of the angular velocity detection apparatus which concerns on background art.

Explanation of symbols

1, 1a, 1b, 1c Angular velocity detection device 2 Carrier generation circuit 3 IV converter 4 gm-C filter 5 First synchronous detection circuit 6 Second synchronous detection circuit 7 Drive control circuit 8, 9 Amplifier 10 Inverter 11, 12 Phase shift 13 Reference oscillation source 14 Frequency divider 15 Amplitude adjustment circuit 16 Peak detector 17 AGC
18 multiplier 42 tuner units 43, 44, 45 gm element 46 operational amplifier 51 multiplier 52 gm-C filter 53 LPF
54 Tuner 55 Switched Capacitor Circuit 101 Gyro Sensor 102 Vibrating Body 103 Drive Electrodes 105, 106 Detection Electrodes 531, 532, 533 gm Elements C1, C2, C3, C4, C5, C6 Capacitors C103, C105, C106 Capacitance CLK1, CLK2 Reference signal Sd Drive signal

Claims (8)

A vibrating body that is displaced by a Coriolis force generated by applying an angular velocity in a vibrating state;
A detection unit that detects a displacement amount of the vibrating body and outputs a detection signal indicating the detected displacement amount;
A filter unit that performs filtering based on the detection signal output from the detection unit;
A drive signal generator that generates a drive signal that is 90 degrees out of phase with the vibration of the vibrating body, based on the signal filtered by the filter;
A drive unit that vibrates the vibrating body according to the drive signal generated by the drive signal generation unit, and
The angular velocity detection device according to claim 1, wherein the filter unit changes a cutoff frequency in accordance with a reference signal having a predetermined frequency. The filter unit is
A tuner unit that outputs a control signal according to the frequency of the reference signal;
A gm element whose amplification factor changes according to a control signal output from the tuner unit;
The angular velocity detection device according to claim 1, wherein the angular velocity detection device is a gm-C filter including a capacitor that filters an output of the gm element. The filter unit is
The angular velocity detection device according to claim 1, wherein the angular velocity detection device is a switched capacitor filter including a switched capacitor circuit in which a pseudo resistance value changes according to a frequency of the reference signal. A carrier signal output unit for outputting a carrier signal having a predetermined frequency set in advance;
A carrier signal applying unit that superimposes a signal component corresponding to a displacement amount of the vibrating body on the carrier signal by applying the carrier signal output from the carrier signal output unit to the vibrating body;
The angular velocity detection device according to claim 1, wherein the detection unit detects a carrier signal on which the signal component is superimposed as the detection signal. A synchronous detection circuit further comprising: a multiplication unit that multiplies the detection signal detected by the detection unit and the carrier signal output from the carrier signal output unit; and a low-pass filter that filters the signal multiplied by the multiplication unit. ,
The angular velocity detection device according to claim 4, wherein the low-pass filter is the filter unit.   6. The angular velocity detection device according to claim 4, wherein a carrier signal output from the carrier signal output unit is used as the reference signal.   The angular velocity detection device according to claim 5, wherein the drive signal generated by the drive signal generation unit is used as the reference signal.   5. The apparatus according to claim 4, further comprising an amplifying unit that amplifies a carrier signal output from the carrier signal output unit to the carrier signal applying unit according to a signal level of a detection signal output from the detection unit. The angular velocity detection device according to any one of 7.

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