JP6671151B2 - Physical quantity detection circuit, electronic equipment and moving object - Google Patents

Description

  The present invention relates to a physical quantity detection circuit, an electronic device, and a moving object.

  2. Description of the Related Art Various electronic devices and systems that include a physical quantity detection device such as an angular velocity detection device and perform predetermined control based on a detected angular velocity are widely used. For example, in a traveling control system of an automobile, a process of preventing side slip of the automobile or detecting rollover is performed based on the detected angular velocity.

  In these electronic devices and systems, erroneous control is performed when the angular velocity detector fails, so measures such as turning on a warning lamp are performed when the angular velocity detector fails, and the failure diagnosis of the angular velocity detector is performed. Various techniques for performing this have been proposed. For example, in Patent Document 1, attention is paid to the fact that an output signal from a vibrator of an angular velocity detecting device includes a detection signal (angular velocity signal) and a self-vibration component (leakage signal) based on excitation vibration of the vibrator. A method is disclosed in which a leakage signal is extracted from an output signal of a vibrator, and the presence or absence of a failure is determined by monitoring the amplitude of the leakage signal. Patent Document 2 discloses a method of correcting a temperature characteristic of an angular velocity signal using a leak signal.

JP 2000-171257 A JP 2012-58010 A

  In the methods described in Patent Literature 1 and Patent Literature 2, when an error occurs in the phase or duty of the reference clock for synchronous detection, an accurate angular velocity signal or a leak signal is not output. There is a possibility that highly reliable signal processing cannot be performed based on the output signal.

  The present invention has been made in view of the above problems, and according to some aspects of the present invention, a physical quantity detection circuit, an electronic device, and a device that can increase the reliability of a circuit that performs synchronous detection. A moving object can be provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
The physical quantity detection circuit according to this application example,
The detection signal from the physical quantity detection element that generates a detection signal corresponding to the magnitude of the physical quantity and a leakage signal of the vibration based on the drive signal by vibrating based on the drive signal, and the detected signal including the leakage signal. A first synchronous detection circuit for synchronously detecting the detection signal based on a first reference clock;
A second synchronous detection circuit that synchronously detects the leak signal based on a second reference clock for the detected signal;
A phase difference monitoring circuit that monitors a phase difference between the first reference clock and the second reference clock;
A physical quantity detection circuit comprising:

  According to this specific example, since the phase difference between the first reference clock and the second reference clock is monitored, abnormality occurs in at least one of the output signal of the first synchronous detection circuit and the output signal of the second synchronous detection circuit. Can be detected. Therefore, a physical quantity detection circuit that can improve the reliability of the circuit that performs synchronous detection can be realized.

[Application Example 2]
The physical quantity detection circuit described above,
The phase difference monitoring circuit,
A counter circuit for counting at least one of a high-level period and a low-level period in an exclusive OR signal of the first reference clock and the second reference clock may be provided.

  According to this application example, a physical quantity detection circuit that can monitor the phase difference between the first reference clock and the second reference clock with a simple configuration can be realized.

[Application Example 3]
The physical quantity detection circuit described above,
The counter circuit may count each of four consecutive periods of the high level period and the low level period in the exclusive OR signal.

  According to this application example, since the frequencies and duty ratios of the first reference clock and the second reference clock can also be monitored, at least one of the output signal of the first synchronous detection circuit and the output signal of the second synchronous detection circuit has an abnormality. What is happening can be detected in more detail. Therefore, a physical quantity detection circuit that can improve the reliability of the circuit that performs synchronous detection can be realized.

[Application Example 4]
The physical quantity detection circuit described above,
A clock frequency of the counter circuit may be higher than a frequency of the exclusive OR signal.

  According to this application example, it is possible to realize a physical quantity detection circuit that can accurately monitor the phase difference between the first reference clock and the second reference clock.

[Application Example 5]
The physical detection circuit described above,
The apparatus may further include a leak signal monitoring circuit that monitors the leak signal.

  According to this application example, it is possible to detect that an abnormality has occurred in the physical quantity detection element or the wiring based on the reliable leak signal. Therefore, a physical quantity detection circuit that can improve the reliability of the circuit that performs synchronous detection can be realized.

[Application Example 6]
The physical quantity detection circuit described above,
With a register,
The physical quantity detection circuit, wherein the phase difference monitoring circuit writes error information to the register when the phase difference is determined to be abnormal.

  According to this application example, the error information can be easily used in another circuit block or device.

[Application Example 7]
The physical quantity detection circuit described above,
The physical quantity detection circuit, wherein the phase difference monitoring circuit outputs an error information signal to the outside when the phase difference is determined to be abnormal.

  According to this application example, the error information signal can be easily used in another circuit block or device.

[Application Example 8]
The physical detection circuit described above,
A first comparator;
A second comparator;
A control unit;
Further comprising
The control unit includes:
When the first comparator is generating the first reference clock,
When it is determined that the monitoring result of the leak signal monitoring circuit is normal and the monitoring result of the phase difference monitoring circuit is abnormal, the second comparator may generate the first reference clock. .

  According to this application example, if the monitoring result of the leak signal monitoring circuit is normal and the monitoring result of the phase difference monitoring circuit is abnormal, an abnormality occurs in the first comparator that generates the first reference clock. Likely to be. Therefore, by switching the comparator that generates the first reference clock from the first comparator to the second comparator, a physical quantity detection circuit that can return to a normal operation can be realized.

[Application Example 9]
The electronic device according to this application example is
An electronic device including any one of the physical quantity detection circuits described above.

  According to this application example, since the physical quantity detection circuit that can increase the reliability of the circuit that performs synchronous detection is provided, an electronic device with high operation reliability can be realized.

[Application Example 10]
The moving object according to this application example is:
A moving object including any of the physical quantity detection circuits described above.

  According to this application example, since the physical quantity detection circuit that can increase the reliability of the circuit that performs synchronous detection is provided, a moving object with high operation reliability can be realized.

It is a figure showing the example of composition of the angular velocity primary detecting device of a 1st embodiment. It is a top view of the vibrating reed of the gyro sensor element. It is a figure for explaining operation of a gyro sensor element. It is a figure for explaining operation of a gyro sensor element. FIG. 4 is a waveform diagram for explaining the principle of detecting angular velocity. FIG. 6 is a waveform diagram for explaining a principle of detecting a leak signal. 5 is a timing chart for explaining the operation of the phase difference monitoring circuit. It is a functional block diagram of a physical quantity detection device of a second embodiment. FIG. 2 is a functional block diagram of the electronic device according to the embodiment. FIG. 2 is a diagram illustrating an example of an external appearance of a smartphone which is an example of an electronic apparatus. It is a figure (top view) showing an example of a mobile concerning this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The drawings used are for convenience of explanation. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, all of the configurations described below are not necessarily essential components of the invention.

1. Physical quantity detection device 1-1. First Embodiment Hereinafter, a physical quantity detection device (angular velocity detection device) that detects an angular velocity as a physical quantity will be described as an example, but the present invention detects any one of various physical quantities such as angular velocity, acceleration, geomagnetism, and pressure. Applicable to any device that can.

  FIG. 1 is a diagram illustrating a configuration example of an angular velocity detection device 1 according to the first embodiment.

  The angular velocity detection device 1 according to the first embodiment includes a gyro sensor element 100 and an angular velocity detection circuit 4 (an example of a physical quantity detection circuit).

  The gyro sensor element 100 (an example of a vibrator) is configured such that a vibrating piece on which a drive electrode and a detection electrode are arranged is sealed in a package (not shown). Generally, airtightness in the package is ensured in order to minimize the impedance of the resonator element and increase the oscillation efficiency.

The resonator element of the gyro sensor element 100 is made of, for example, a piezoelectric single crystal such as quartz (SiO ₂ ), lithium tantalate (LiTaO ₃ ), or lithium niobate (LiNbO ₃ ), or a piezoelectric ceramic such as lead zirconate titanate (PZT). Or a piezoelectric thin film such as zinc oxide (ZnO) or aluminum nitride (AlN) sandwiched between drive electrodes on a part of the surface of a silicon semiconductor. There may be.

  In the present embodiment, the gyro sensor element 100 is constituted by a so-called double T-shaped vibrating reed having two T-shaped driving vibrating arms. However, the vibrating reed of the gyro sensor element 100 may be, for example, a tuning fork type, or a vibrating reed of a triangular prism, a quadrangular prism, a columnar shape, or the like.

  FIG. 2 is a plan view of the resonator element of the gyro sensor element 100 according to the present embodiment.

  The gyro sensor element 100 of the present embodiment has a double T-shaped vibrating reed formed by a Z-cut quartz substrate. Since the resonator element made of quartz has a very small change in the resonance frequency with respect to the temperature change, there is an advantage that the detection accuracy of the angular velocity can be improved. Note that the X axis, Y axis, and Z axis in FIG. 2 indicate axes of quartz.

As shown in FIG. 2, the vibrating reed of the gyro sensor element 100 has driving vibrating arms 101a and 101b extending from two driving bases 104a and 104b in the + Y axis direction and the −Y axis direction, respectively. Driving electrodes 112 and 113 are formed on the side and upper surfaces of the driving vibration arm 101a, respectively, and driving electrodes 113 and 112 are formed on the side and upper surfaces of the driving vibration arm 101b, respectively. The drive electrodes 112 and 113 are respectively connected to the drive circuit 20 via the external output terminal 11 and the external input terminal 12 of the angular velocity detection circuit 4 shown in FIG.

  The driving bases 104a and 104b are connected to the rectangular detection base 107 via connecting arms 105a and 105b extending in the −X axis direction and the + X axis direction, respectively.

  The detection vibrating arm 102 extends from the detection base 107 in the + Y axis direction and the −Y axis direction. Detection electrodes 114 and 115 are formed on the upper surface of the detection vibration arm 102, and a common electrode 116 is formed on the side surface of the detection vibration arm 102. The detection electrodes 114 and 115 are connected to the detection circuit 30 via the external input terminals 13 and 14 of the angular velocity detection circuit 4 shown in FIG. 1, respectively. Further, the common electrode 116 is grounded.

  When an AC voltage is applied as a drive signal between the drive electrodes 112 and 113 of the drive vibrating arms 101a and 101b, as shown in FIG. In addition, the distal ends of the two drive vibration arms 101a and 101b perform bending vibration (excitation vibration) that alternately approach and separate from each other.

  In this state, when an angular velocity about the Z axis as the rotation axis is applied to the vibrating piece of the gyro sensor element 100, the driving vibrating arms 101a and 101b are Coriolis in a direction perpendicular to both the direction of the bending vibration indicated by the arrow B and the Z axis. Get the power of As a result, as shown in FIG. 4, the connecting arms 105a and 105b vibrate as indicated by arrow C. Then, the detection vibrating arm 102 performs bending vibration as indicated by an arrow D in conjunction with the vibration (arrow C) of the connecting arms 105a and 105b. The bending vibration of the detection vibration arm 102 due to the Coriolis force and the bending vibration (excitation vibration) of the driving vibration arms 101a and 101b are out of phase by 90 °.

  By the way, if the magnitude of the vibration energy or the magnitude of the vibration amplitude when the driving vibration arms 101a and 101b perform the bending vibration (excitation vibration) are equal to the two driving vibration arms 101a and 101b, the driving vibration arms 101a and 101b are used. The vibration energy of 101b is balanced, and the detection vibration arm 102 does not bend and vibrate when the angular velocity is not applied to the gyro sensor element 100. However, when the balance between the vibration energies of the two driving vibrating arms 101a and 101b is lost, bending vibration occurs in the detection vibrating arm 102 even when the angular velocity is not applied to the gyro sensor element 100. This bending vibration is called leakage vibration, which is the bending vibration indicated by arrow D similarly to the vibration based on the Coriolis force, but has the same phase as the drive signal.

  Then, an AC charge based on these bending vibrations is generated on the detection electrodes 114 and 115 of the detection vibration arm 102 by the piezoelectric effect. Here, the AC charge generated based on the Coriolis force changes according to the magnitude of the Coriolis force (in other words, the magnitude of the angular velocity applied to the gyro sensor element 100). On the other hand, the AC charge generated based on the leakage vibration is constant irrespective of the magnitude of the angular velocity applied to the gyro sensor element 100.

  In addition, a rectangular weight portion 103 having a wider width than the driving vibration arms 101a and 101b is formed at the tip of the driving vibration arms 101a and 101b. By forming the weight portion 103 at the tip of the driving vibrating arms 101a and 101b, the Coriolis force can be increased and a desired resonance frequency can be obtained with a relatively short vibrating arm. Similarly, a weight portion 106 wider than the detection vibration arm 102 is formed at the tip of the detection vibration arm 102. By forming the weight portion 106 at the tip of the detection vibrating arm 102, the AC charge generated in the detection electrodes 114 and 115 can be increased.

  As described above, the gyro sensor element 100 uses the Z-axis as a detection axis to detect an AC charge (detection signal) based on Coriolis force and an AC charge (leakage signal) based on leakage vibration of the excitation vibration. Output via.

  Returning to FIG. 1, the angular velocity detection circuit 4 includes a drive circuit 20, a detection circuit 30, a phase difference monitoring circuit 40, a leak signal monitoring circuit 50, and a control unit 60.

  The drive circuit 20 generates a drive signal 21 for exciting and vibrating the gyro sensor element 100 and supplies the drive signal 21 to the drive electrode 112 of the gyro sensor element 100 via the external output terminal 11. The drive circuit 20 receives a drive signal 22 generated on the drive electrode 113 by the excitation vibration of the gyro sensor element 100 via the external input terminal 12 and drives the drive signal 22 so that the amplitude of the drive signal 22 is kept constant. Feedback control of the amplitude level of the signal 21 is performed.

  The drive circuit 20 includes an I / V conversion circuit (current / voltage conversion circuit) 210, an AC amplification circuit 220, an amplitude adjustment circuit 230, a first comparator 241, a second comparator 242, and a switch 243.

  The drive current flowing through the resonator element of the gyro sensor element 100 is converted by the I / V conversion circuit 210 into an AC voltage signal.

  The AC voltage signal output from the I / V conversion circuit 210 is input to the AC amplification circuit 220 and the amplitude adjustment circuit 230. The AC amplification circuit 220 amplifies the input AC voltage signal, clips the AC voltage signal at a predetermined voltage value, and outputs a square wave voltage signal 23. The amplitude adjustment circuit 230 changes the amplitude of the square wave voltage signal 23 according to the level of the AC voltage signal output from the I / V conversion circuit 210, and controls the AC amplification circuit 220 so that the driving current is kept constant. I do.

  The square wave voltage signal 23 is supplied to the driving electrode 112 of the vibrating reed of the gyro sensor element 100 via the external output terminal 11. In this manner, the gyro sensor element 100 continuously excites a predetermined drive vibration as shown in FIG. Also, by keeping the drive current constant, the drive vibrating arms 101a and 101b of the gyro sensor element 100 can obtain a constant vibration speed. Therefore, the vibration speed that generates the Coriolis force becomes constant, and the sensitivity can be made more stable.

  The first comparator 241 compares the square wave voltage signal 23 with the reference voltage Vref, generates a first reference clock 24, and outputs the first reference clock 24 to a first synchronous detection circuit 350 (described later) via a switch 243.

  The second comparator 242 compares the square wave voltage signal 23 with the reference voltage Vref, generates a square wave voltage signal 23a, and outputs it to a phase shift circuit 340 (described later).

  The detection circuit 30 receives AC charges (detection currents) 31 and 32 generated at the detection electrodes 114 and 115 of the gyro sensor element 100 via the external input terminals 13 and 14, respectively, and these AC charges (detection currents) are provided. Extract the desired components contained in.

  The detection circuit 30 includes charge amplifiers 310 and 312, a differential amplifier circuit 320, an AC amplifier circuit 330, a phase shift circuit 340, a first synchronous detection circuit 350, a second synchronous detection circuit 352, integration circuits 360 and 362, and a DC amplification circuit. 370 and 372 are included.

  The charge amplifier 310 receives an AC charge including a detection signal and a leakage signal from the detection electrode 114 of the vibrating reed of the gyro sensor element 100 via the external input terminal 13.

  Similarly, the charge amplifier 312 receives an AC charge including a detection signal and a leakage signal from the detection electrode 115 of the vibrating reed of the gyro sensor element 100 via the external input terminal 14.

  The charge amplifiers 310 and 312 convert the input AC charges into AC voltage signals based on the reference voltage Vref. Vref is generated by a reference power supply circuit (not shown) based on an external power supply input from outside.

  The differential amplifier circuit 320 differentially amplifies the output signal of the charge amplifier 310 and the output signal of the charge amplifier 312. The differential amplifier circuit 320 is for erasing the in-phase component and adding and amplifying the anti-phase component.

  The AC amplifier circuit 330 amplifies the output signal of the differential amplifier circuit 320. The output signal of the AC amplification circuit 330 includes a detection signal corresponding to the magnitude of the physical quantity (angular velocity) and a leakage signal of vibration based on the drive signal. 352.

  The first synchronous detection circuit 350 synchronously detects the detection signal of the detection target signal 33 based on the first reference clock 24. For example, when the voltage level of the square wave voltage signal 23 is higher than the reference voltage Vref, the first synchronous detection circuit 350 selects the detection target signal 33, and the voltage level of the square wave voltage signal 23 is lower than the reference voltage Vref. At this time, it can be configured as a switch circuit for selecting a signal obtained by inverting the detection signal 33 with respect to the reference voltage Vref.

The second synchronous detection circuit 352 performs synchronous detection on the detected signal 33 based on the second reference clock 34 in which the phase shift circuit 340 delays the square wave voltage signal 23a by 90 °. The second synchronous detection circuit 352, for example, when the voltage level of the second reference clock 34 is higher than the reference voltage Vref is selected to be detected signal 33, than the voltage level of the reference voltage V _ref of the second reference clock 34 When the signal is low, it can be configured as a switch circuit for selecting a signal obtained by inverting the detection signal 33 with respect to the reference voltage Vref.

  The output signal of the first synchronous detection circuit 350 is smoothed into a DC voltage signal by the integration circuit 360 and input to the DC amplification circuit 370 as the angular velocity signal 36a.

  The output signal of the second synchronous detection circuit 352 is smoothed into a DC voltage signal by the integration circuit 362 and input to the DC amplification circuit 372 as a leakage signal 36b.

  The DC amplification circuit 380 amplifies or attenuates the angular velocity signal 36a to a desired level, and outputs it as a detection signal 37a to the outside via the external output terminal 16. Then, an external device (not shown) can obtain information on the angular velocity by monitoring the detection signal 37a.

  The DC amplification circuit 382 amplifies or attenuates the leak signal 36b to a desired level, and outputs the leak signal 37b to the outside via the external output terminal 17 as the leak signal 37b. An external device (not shown) can determine whether or not there is a failure such as a failure or disconnection of the gyro sensor element 100 by monitoring the leak signal 37b.

  Next, the principle of detecting the angular velocity of the angular velocity detecting device 1 shown in FIG. 1 will be described with reference to the waveform diagram of FIG. FIG. 5 is a diagram showing an example of a signal waveform at points A to J in FIG. 1, in which the horizontal axis represents time and the vertical axis represents voltage.

In a state where the vibrating reed of the gyro sensor element 100 is vibrating, a current fed back from the driving electrode 113 of the vibrating reed of the gyro sensor element 100 is converted into an output (point A) of the I / V conversion circuit 210. An AC voltage with a constant frequency is generated. That is, I /
A sine wave voltage signal having a constant frequency is generated at the output (point A) of the V conversion circuit 210.

  Then, at the output (point B) of the first comparator 241, a first reference clock 24 having a constant amplitude Vc and an amplified output signal of the I / V conversion circuit 210 (signal at point A) is generated. .

  When an angular velocity is applied to the gyro sensor element 100, signals generated at the detection electrodes 114 and 115 of the vibrating element of the gyro sensor element 100 include a detection signal and a leak signal. The magnitude of this detection signal changes according to the magnitude of the Coriolis force. On the other hand, the leakage signal has a constant magnitude regardless of the magnitude of the angular velocity. However, in FIG. 5, since the purpose is to explain the principle of detecting the angular velocity, a signal waveform focusing on only the detection signal is shown. In the following description, description will be made focusing on only the detection signal.

  The detection signals (AC charges) of the signals generated on the detection electrodes 114 and 115 of the vibrating element of the gyro sensor element 100 are converted into AC voltage signals by the charge amplifiers 310 and 312, respectively. As a result, a sine wave voltage signal having the same frequency as the output signal (signal at point B) of the AC amplifier circuit 220 is generated at the outputs (points C and D) of the charge amplifiers 310 and 312. Here, the phase of the output signal of the charge amplifier 310 (the signal at the point C) is the same as the phase of the output signal of the AC amplifier circuit 220 (the signal at the point B). Further, the phase of the output signal (signal at point D) of the charge amplifier 312 is opposite to the phase of the output signal (signal at point C) of the charge amplifier 310 (shifted by 180 °).

  The output signals of the charge amplifiers 310 and 312 (the signal at the point C and the signal at the point D) are differentially amplified by the differential amplifier circuit 320, and the output of the AC amplifier circuit 330 (point E) is the output of the charge amplifier 310 (point E). A sine wave voltage signal having the same frequency and the same phase as the sine wave voltage signal generated at point C) is generated. This sine wave voltage signal generated at the output (point E) of the AC amplifier circuit 330 is a signal obtained by amplifying the detection signal of the signal generated at the detection electrodes 114 and 115 of the gyro sensor element 100.

  The output signal (signal at point E) of the AC amplifier circuit 330 is synchronously detected by the first synchronous detection circuit 350 based on the first reference clock 24. Here, since the output signal (signal at point E) of the AC amplifier circuit 330 and the first reference clock 24 (signal at point B) have the same phase, the output signal of the first synchronous detection circuit 350 (signal at point G). Is a signal obtained by full-wave rectifying the output signal (signal at point E) of the AC amplifier circuit 330. As a result, a DC voltage signal (angular velocity signal 36a) having a voltage value V1 corresponding to the magnitude of the angular velocity is generated at the output (point H) of the integrating circuit 360.

  On the other hand, at the output (point F) of the phase shift circuit 340, a second reference clock 34 whose phase is delayed by 90 ° with respect to the first reference clock 24 (signal at point B) is generated. The signal (signal at point E) is synchronously detected by the second synchronous detection circuit 352 based on the second reference clock 34. Here, since the output signal of the AC amplifier circuit 330 (signal at point E) and the second reference clock 34 (signal at point F) are out of phase by 90 °, the output signal of the second synchronous detection circuit 352 (point I) ), The integral of a voltage higher than the reference voltage Vref is equal to the integral of a voltage lower than the reference voltage Vref. As a result, the detection signal is canceled, and a DC voltage signal of the reference voltage Vref is generated at the output (point J) of the integration circuit 362.

When the angular velocity in the direction opposite to that of FIG. 5 is applied to the angular velocity detector 1, both the output signal of the charge amplifier 310 (signal at point C) and the output signal of the charge amplifier 312 (signal at point D) are equal to the reference voltage. The waveform is inverted around Vref. As a result, the angular velocity signal 36a (the signal at the point H) is a signal having a voltage lower than the reference voltage Vref, contrary to FIG. Since the voltage value of the angular velocity signal 36a is proportional to the magnitude of the Coriolis force (magnitude of the angular velocity) and its polarity is determined by the rotation direction, the angular velocity applied to the angular velocity detecting device 1 is calculated based on the angular velocity signal 36a. can do.

  Next, the principle of detecting a leak signal of the angular velocity detecting device 1 shown in FIG. 1 will be described with reference to the waveform diagram of FIG. FIG. 6 is a diagram showing an example of a signal waveform at points A to J in FIG. 1, in which the horizontal axis represents time and the vertical axis represents voltage.

  6, signal waveforms at points A, B, and F are the same as those in FIG. 5, and a description thereof will be omitted. In FIG. 6, since the purpose is to explain the principle of detecting a leak signal, a signal waveform focusing on only the leak signal is shown. In the following description, description will be made focusing only on the leak signal.

  Signal leakage signals (AC charges) generated at the detection electrodes 114 and 115 of the vibrating reed of the gyro sensor element 100 are converted into AC voltage signals by the charge amplifiers 310 and 312, respectively. As a result, a sine wave voltage signal having the same frequency as the output signal of the first comparator 241 (the signal at the point B) is generated at the outputs (points C and D) of the charge amplifiers 310 and 312. Here, the phase of the output signal (signal at point C) of the charge amplifier 310 is shifted by 90 ° from the output signal of the first comparator 241 (signal at point B). Further, the phase of the output signal (signal at point D) of the charge amplifier 312 is opposite to the phase of the output signal (signal at point C) of the charge amplifier 310 (shifted by 180 °).

  The output signals of the charge amplifiers 310 and 312 (the signal at the point C and the signal at the point D) are differentially amplified by the differential amplifier circuit 320, and the output of the AC amplifier circuit 330 (point E) is the output of the charge amplifier 310 (point E). A sine wave voltage signal having the same frequency and the same phase as the sine wave voltage signal generated at point C) is generated. This sine wave voltage signal generated at the output (point E) of the AC amplifier circuit 330 is a signal obtained by amplifying a leakage signal of a signal generated at the detection electrodes 114 and 115 of the gyro sensor element 100.

  The output signal (signal at point E) of the AC amplifier circuit 330 is synchronously detected by the first synchronous detection circuit 350 based on the first reference clock 24. Here, since the output signal (signal at point E) of the AC amplifier circuit 330 and the first reference clock 24 (signal at point B) are 90 ° out of phase, the output signal of the first synchronous detection circuit 350 (point G) ), The integral of a voltage higher than the reference voltage Vref is equal to the integral of a voltage lower than the reference voltage Vref. As a result, the leakage signal is canceled, and a DC voltage signal of the reference voltage Vref is generated at the output (point H) of the integration circuit 360.

  On the other hand, the output signal (signal at point E) of the AC amplifier circuit 330 is synchronously detected by the second synchronous detection circuit 352 based on the second reference clock 34. Here, since the output signal of the AC amplifier circuit 330 (signal at point E) and the second reference clock 34 (signal at point F) are in phase, the output signal of the second synchronous detection circuit 352 (signal at point I). Is a signal obtained by full-wave rectifying the output signal (signal at point E) of the AC amplifier circuit 330. As a result, a DC voltage signal (leakage signal 36b) having a voltage value V2 corresponding to the magnitude of the leakage signal is generated at the output (point J) of the integration circuit 362.

  Although the voltage value of the leak signal 36b is proportional to the magnitude of the leak signal, the magnitude of the leak signal is constant unless there is a failure. Therefore, by monitoring the leak signal 36b, it is determined whether or not the angular velocity detecting device 1 has a failure. can do.

  The reliability of the fault detection using the leak signal 36b depends on the reliability of the extracted leak signal, which is a premise for fault detection. Therefore, in applications requiring high reliability, if the reliability of the leak signal is low, processing such as detecting and notifying the leak signal is required.

Therefore, the angular velocity detection circuit 4 of the present embodiment includes a phase difference monitoring circuit 40 that monitors a phase difference between the first reference clock 24 and the second reference clock 34. If the phase difference between the first reference clock 24 and the second reference clock 34 is outside the predetermined range, the phase difference monitoring circuit 40 outputs the error information signal 44 to the external output terminal 18 according to the present embodiment. Since the phase difference between the first reference clock 24 and the second reference clock 34 is monitored, it is possible to determine that an abnormality has occurred in at least one of the output signal of the first synchronous detection circuit 350 and the output signal of the second synchronous detection circuit 352. Can be detected. Therefore, the angular velocity detection circuit 4 (physical quantity detection circuit) and the angular velocity detection apparatus 1 (physical quantity detection apparatus) that can improve the reliability of the circuit that performs synchronous detection can be realized. Further, by outputting the error information signal 44 to the outside, the error information signal can be easily used in another circuit block or device.

  In the present embodiment, the phase difference monitoring circuit 40 includes an exclusive OR circuit 41, a counter circuit 42, and a determination circuit 43. The exclusive OR circuit 41 generates an exclusive OR signal 41a of the first reference clock 24 and the second reference clock 34. The counter circuit 42 counts at least one of a high level period and a low level period of the exclusive OR signal 41a generated by the exclusive OR circuit 41. The determination circuit 43 determines whether there is an abnormality based on the count result of the counter circuit 42. The determination circuit 43 outputs an error information signal 44 based on the determination result. Further, the judgment circuit 43 outputs a signal 45 corresponding to the judgment result to the control unit 60.

  FIG. 7 is a timing chart for explaining the operation of the phase difference monitoring circuit 40. FIG. 7 is a diagram showing an example of signal waveforms at point B (first reference clock 24), point F (second reference clock 34) and point K (exclusive OR signal 41a) in FIG. Represents time, and the vertical axis represents voltage. The signal waveforms at points B and F are the same as in FIGS. The signal waveform at point K is an exclusive OR of the signal waveforms at points B and F. The periods T1 and T3 are high-level periods of the exclusive OR signal 41a (point K), and the periods T2 and T4 are low levels of the exclusive OR signal 41a (point K).

  When the duty ratio of the first reference clock 24 and the second reference clock 34 is exactly 50% and the second reference clock 34 is exactly 90 ° delayed from the first reference clock 24, the periods T1 to T4 Have the same length. On the other hand, if the duty ratio of the first reference clock 24 and the second reference clock 34 is exactly 50% and the second reference clock 34 is slightly behind the first reference clock 24 by 90 °, the period The lengths of T1 and T3 increase, and the lengths of T2 and T4 decrease. If the duty ratio of the first reference clock 24 and the second reference clock 34 is exactly 50% and the second reference clock 34 is slightly ahead of the first reference clock 24 by 90 °, the period The lengths of T1 and T3 are reduced, and the lengths of T2 and T4 are increased. Therefore, the phase difference between the first reference clock 24 and the second reference clock 34 can be monitored by counting at least one of the high level period and the low level period by the counter circuit 42.

  According to the present embodiment, the angular velocity detection circuit 4 (physical quantity detection circuit) and the angular velocity detection apparatus 1 (physical quantity detection apparatus) capable of monitoring the phase difference between the first reference clock 24 and the second reference clock 34 with a simple configuration are realized. it can.

  In the present embodiment. The counter circuit 42 may count each of four consecutive periods of the high level period and the low level period in the exclusive OR signal 41a.

  According to the present embodiment, in addition to the phase difference between the first reference clock 24 and the second reference clock 34, the frequency and duty ratio of the first reference clock 24 and the second reference clock 34 can be monitored. It is possible to detect in more detail whether an abnormality has occurred in at least one of the output signal of the detection circuit 350 and the output signal of the second synchronous detection circuit 352. Therefore, the angular velocity detection circuit 4 (physical quantity detection circuit) and the angular velocity detection apparatus 1 (physical quantity detection apparatus) that can improve the reliability of the circuit that performs synchronous detection can be realized.

  In the present embodiment, the clock frequency of the counter circuit 42 is preferably higher than the frequency of the exclusive OR signal 41a. For example, the clock frequency of the counter circuit 42 may be set to about 100 times the frequency of the exclusive OR signal 41a in accordance with the required accuracy of the phase difference.

  According to the present embodiment, the angular velocity detection circuit 4 (physical quantity detection circuit) and the angular velocity detection apparatus 1 (physical quantity detection apparatus) capable of accurately monitoring the phase difference between the first reference clock 24 and the second reference clock 34 can be realized.

  In the present embodiment, the angular velocity detection circuit 4 may further include a leak signal monitoring circuit 50 that monitors the leak signal 36b. The leak signal monitoring circuit 50 outputs the error information signal 52 to the external output terminal 19 when the leak signal 36b is out of the predetermined range. In addition, a signal 53 based on the monitoring result is output to the control unit 60.

  According to this application example, it is possible to detect that an abnormality has occurred in the gyro sensor element 100 (physical quantity detection element) and the wiring based on the reliable leak signal 36b. Therefore, the angular velocity detection circuit 4 (physical quantity detection circuit) and the angular velocity detection apparatus 1 (physical quantity detection apparatus) that can improve the reliability of the circuit that performs synchronous detection can be realized.

  In the present embodiment, when the first comparator 241 is generating the first reference clock 24, the control unit 60 determines that the monitoring result of the leak signal monitoring circuit 50 is normal and that the phase difference monitoring circuit 40 If it is determined that the monitoring result is abnormal, the second comparator 242 may generate the first reference clock 24. In the example illustrated in FIG. 1, the control unit 60 controls the switch 243 based on the signal 53 output from the leak signal monitoring circuit 50 and the signal 45 output from the determination circuit 43. By switching the connection destination of the switch 243 from the first comparator 241 to the second comparator 242, the second comparator 242 can generate the first reference clock 24.

  According to the present embodiment, when the monitoring result of the leak signal monitoring circuit 50 is normal and the monitoring result of the phase difference monitoring circuit 40 is abnormal, the first comparator 241 that generates the first reference clock 24 It is highly possible that an abnormality has occurred. Therefore, by switching the comparator that generates the first reference clock 24 from the first comparator 241 to the second comparator 242, it is possible to return to a normal operation. The device 1 (physical quantity detection device) can be realized.

  In the present embodiment, when the first comparator 241 is generating the first reference clock 24, the control unit 60 determines that the monitoring result of the leak signal monitoring circuit 50 is normal and that the phase difference monitoring circuit 40 When it is determined that the monitoring result of the duty ratio is abnormal, the threshold value of the first comparator 241 may be corrected. For example, when the high-level period is too long and the low-level period is too short, the threshold of the first comparator 241 is changed to be higher. Further, for example, when the low level period is too short and the high level period is too long, the threshold value of the first comparator 241 is changed to be low. This correction can improve the duty ratio.

  In the present embodiment, the angular velocity detection circuit 4 includes a register 47. The register 47 is configured to be able to output stored information as a digital signal 48 to the outside via the external output terminal 18a. In addition, the determination circuit 43 may write error information to the register 47 when it determines that there is an abnormality based on the count result of the counter circuit 42. In the example illustrated in FIG. 1, the determination circuit 43 writes the error information in the register 47 by outputting the error information write signal 46 to the register 47. Thus, the error information can be easily used in another circuit block or device.

1-2. Second Embodiment FIG. 8 is a functional block diagram of a physical quantity detection device 1000 according to a second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

  The physical quantity detection device 1000 detects the angular velocity in one axis direction and the acceleration in two axis directions as physical quantities. The physical quantity detection device 1000 includes a gyro sensor element 100 and an angular velocity detection circuit 4 as a configuration for detecting an angular velocity. The physical quantity detection device 1000 includes a detection element 400x, a detection element 400y, and an acceleration detection circuit 5 as a configuration for detecting acceleration. In addition, the physical quantity detection device 1000 includes the temperature sensor 3 for performing correction based on temperature.

  The physical quantity detection device 1000 of the present embodiment further includes a selection circuit 6, an ADC (Analog-to-digital converter) 7, a digital processing circuit 8, an interface circuit 9, and a failure diagnosis circuit 10.

  In the present embodiment, the configuration excluding the gyro sensor element 100, the detection element 400x, and the detection element 400y is configured as a physical quantity detection circuit (integrated circuit device) 2. The physical quantity detection device 1000 of the present embodiment may have a configuration in which some of these components (elements) are omitted, or a configuration in which a new configuration (element) is added.

  The temperature sensor 3 outputs a temperature signal 408 corresponding to the temperature to the selection circuit 6.

  The angular velocity detection circuit 4 outputs a detection signal 37a corresponding to the angular velocity to the selection circuit 6. Further, the angular velocity detection circuit 4 outputs the error information signal 44 and the error information signal 52 to the failure diagnosis circuit 10.

  The detection element 400x and the detection element 400y are configured by capacitance type acceleration detection elements. The detection element 400x receives the carrier signal 401 from the acceleration detection circuit 5, and differentially outputs a detection signal 402 and a detection signal 403 corresponding to the detected acceleration to the acceleration detection circuit 5. The detection element 400y receives the carrier signal 401 from the acceleration detection circuit 5, and differentially outputs a detection signal 404 and a detection signal 405 corresponding to the detected acceleration to the acceleration detection circuit 5.

  The acceleration detection circuit 5 outputs an acceleration signal 406 corresponding to the acceleration to the selection circuit 6 based on the detection signals 402 to 405. Further, the acceleration detection circuit 5 outputs information on an abnormality that has occurred in the acceleration detection circuit 5 to the failure diagnosis circuit 10 as an error information signal 407.

  The selection circuit 6 sequentially selects one of the input signals and outputs it as a signal 409 to the ADC 7.

  The ADC 7 converts the input signal into a digital signal and outputs the digital signal to the digital processing circuit 8 as a signal 410.

  The digital processing circuit 8 performs various digital processes on the input signal and outputs the signal as a signal 411 to the interface circuit 9. As the digital processing, for example, a filter processing or a processing for correcting a temperature characteristic may be performed.

  The failure diagnosis circuit 10 determines whether an abnormality has occurred in at least one of the angular velocity detection circuit 4, the acceleration detection circuit 5, the gyro sensor element 100, the detection element 400x, and the detection element 400y based on the input signal. It makes a determination and outputs the result of the determination to the interface circuit 9 as a signal 412.

  The interface circuit 9 converts the input signal into a predetermined communication format and outputs it as a signal 413 to the outside.

  Also in the physical quantity detection device 1000 of the second embodiment, the same effect is exerted for the same reason as in the first embodiment.

2. Electronic Device FIG. 9 is a functional block diagram of an electronic device 500 according to the present embodiment. The same components as those in the above-described embodiments are denoted by the same reference numerals, and detailed description will be omitted.

  The electronic device 500 according to the present embodiment is an electronic device 500 including the angular velocity detection device 1 (physical quantity detection device) including the angular velocity detection circuit 4 (physical quantity detection circuit). In the example illustrated in FIG. 9, the electronic device 500 includes the angular velocity detection device 1, a CPU (Central Processing Unit) 520, an operation unit 530, a ROM (Read Only Memory) 540, a RAM (Random Access Memory) 550, a communication unit 560, A display unit 570 and a sound output unit 580 are included. Note that the electronic device 500 according to the present embodiment may have a configuration in which some of the components (each unit) shown in FIG. 9 are omitted or changed, or other components are added.

  The CPU 520 performs various calculation processes and control processes using clock pulses output from a clock signal generation circuit (not shown) according to a program stored in the ROM 540 or the like. More specifically, the CPU 520 performs various processes according to an operation signal from the operation unit 530, a process of controlling the communication unit 560 to perform data communication with the outside, and a process of displaying various information on the display unit 570. A process of transmitting a display signal, a process of outputting various sounds to the sound output unit 580, and the like are performed.

  The operation unit 530 is an input device including an operation key, a button switch, and the like, and outputs an operation signal according to a user operation to the CPU 520.

  The ROM 540 stores programs and data for the CPU 520 to perform various calculation processes and control processes.

  The RAM 550 is used as a work area of the CPU 520, and temporarily stores programs and data read from the ROM 540, data input from the operation unit 530, calculation results executed by the CPU 520 according to various programs, and the like.

  The communication unit 560 performs various controls for establishing data communication between the CPU 520 and the external device.

  The display unit 570 is a display device configured by an LCD (Liquid Crystal Display), an electrophoretic display, or the like, and displays various information based on a display signal input from the CPU 520.

  The sound output unit 580 is a device that outputs sound such as a speaker.

  When the CPU 520 receives, from the angular velocity detecting device 1, an error signal indicating that there is some abnormality in the angular velocity detecting device 1, the CPU 520 according to the first or second embodiment described above, in order to identify the location where the abnormality has occurred. A command instructing the angular velocity signal processing circuit 4 to determine that at least one of the output signal of the first synchronous detection circuit 350 and the output signal of the second synchronous detection circuit 352 has an abnormality is sent to the angular velocity detection device 1. It may be transmitted to.

  According to the electronic device 500 according to the present embodiment, since the angular velocity detection circuit 4 (physical quantity detection circuit) that can increase the reliability of the circuit that performs synchronous detection is provided, the electronic device 500 with high operation reliability is provided. Can be realized.

  Various electronic devices can be considered as the electronic device 500. For example, personal computers (for example, mobile personal computers, laptop personal computers, tablet personal computers), mobile terminals such as mobile phones, digital cameras, inkjet discharge devices (for example, inkjet printers), routers and switches, etc. Storage area network equipment, local area network equipment, mobile terminal base station equipment, televisions, video cameras, video recorders, car navigation devices, pagers, electronic organizers (including those with communication functions), electronic dictionaries, calculators, electronic games Equipment, game controllers, word processors, workstations, videophones, security TV monitors, electronic binoculars, POS (point of sale) terminals, medical equipment (eg For example, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasonic diagnostic devices, electronic endoscopes), fish finder, various measuring devices, instruments (for example, instruments for vehicles, aircraft, and ships), power meters , A flight simulator, a head mounted display, a motion trace, a motion tracking, a motion controller, a PDR (pedestrian position and orientation measurement), and the like.

  FIG. 10 is a diagram illustrating an example of the external appearance of a smartphone that is an example of the electronic device 500. The smartphone as the electronic device 500 includes a button as the operation unit 530 and an LCD as the display unit 570. Since the smartphone as the electronic device 500 includes the angular velocity detection circuit 4 (physical quantity detection circuit) that can increase the reliability of the circuit that performs synchronous detection, the electronic device 500 with high operation reliability is realized. be able to.

3. Moving Body FIG. 11 is a diagram (top view) illustrating an example of the moving body 600 according to the present embodiment. The same components as those in the above-described embodiments are denoted by the same reference numerals, and detailed description will be omitted.

  The moving object 600 according to the present embodiment is a moving object 400 including a physical quantity detection device 1000 including the angular velocity detection circuit 4 (physical quantity detection circuit). In the example shown in FIG. 11, the moving object 600 includes a controller 620 that performs various controls such as an engine system, a brake system, and a keyless entry system, a controller 630, a controller 640, a battery 650, and a backup battery 660. It is configured. Note that the moving object 600 according to the present embodiment may have a configuration in which some of the components (each unit) shown in FIG. 11 are omitted or changed, or a configuration in which another component is added.

  According to the moving object 600 according to the present embodiment, since the angular velocity detection circuit 4 (physical quantity detection circuit) that can increase the reliability of the circuit that performs synchronous detection is provided, the moving object 600 with high operation reliability is provided. Can be realized.

  As the moving body 600, various moving bodies can be considered, and examples thereof include an automobile (including an electric car), an aircraft such as a jet aircraft and a helicopter, a ship, a rocket, an artificial satellite, and the like.

  The present invention is not limited to this embodiment, and various modifications can be made within the scope of the present invention.

  The above-described embodiments and modifications are merely examples, and the present invention is not limited to these. For example, each embodiment and each modified example can be appropriately combined.

  The invention includes substantially the same configuration as the configuration described in the embodiment (for example, a configuration having the same function, method, and result, or a configuration having the same object and effect). Further, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. Further, the invention includes a configuration having the same operation and effect as the configuration described in the embodiment or a configuration capable of achieving the same object. The invention also includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Angular velocity detection device, 2 ... Physical quantity detection circuit (integrated circuit device), 3 ... Temperature sensor, 4 ... Angular velocity detection circuit, 5 ... Acceleration detection circuit, 6 ... Selection circuit, 7 ... ADC, 8 ... Digital processing circuit, 9 ... Interface circuit, 10 ... Failure diagnosis circuit, 11, 16-19 ... External output terminal, 18a ... External output terminal, 12-14 ... External input terminal, 20 ... Drive circuit, 21,22 ... Drive signal, 23,23a ... Square wave voltage signal, 24: first reference clock, 30: detection circuit, 31, 32: AC charge (detection current), 33: detected signal, 34: second reference clock, 36a, 37a: angular velocity signal, 36b, 37b leak signal, 40 phase difference monitoring circuit, 41 exclusive OR circuit, 41a exclusive OR signal, 42 counter circuit, 43 determination circuit, 44 error information signal, 45 signal 46, an error information write signal, 47, a register, 48, a digital signal, 50, a leak signal monitoring circuit, 52, an error information signal, 53, a signal, 60, a control unit, 62, a control signal, 70, a temperature sensor, 72 ... temperature detection signal, 100 ... gyro sensor element, 101a to 101b ... drive vibration arm, 102 ... detection vibration arm, 103 ... weight part, 104a to 104b ... drive base, 105a to 105b ... connection arm, 106 ... weight part, 107: base for detection, 112 to 113: drive electrode, 114 to 115: detection electrode, 116: common electrode, 210: I / V conversion circuit (current / voltage conversion circuit), 220: AC amplification circuit, 230: amplitude adjustment circuit , 241 first comparator, 242 second comparator, 243 switch, 310, 312 charge amplifier, 320 differential Width circuit, 330: AC amplifier circuit, 340: phase shift circuit, 350: first synchronous detection circuit, 352: second synchronous detection circuit, 360, 362: integration circuit, 370, 372: DC amplification circuit, 400x, 400y ... Detecting element, 401 ... Carrier wave signal, 402-405 ... Detection signal, 406 ... Acceleration signal, 407 ... Error information signal, 408 ... Temperature signal, 409-413 ... Signal, 500 ... Electronic equipment, 520 ... CPU, 530 ... Operation unit 540 ROM, 550 RAM 560 communication unit 570 display unit 580 audio output unit 600 mobile unit 620 controller 630 controller 640 controller 650 battery and 660 backup Battery, 1000: Physical quantity detection device

Claims (10)

The detection signal from the physical quantity detection element that generates a detection signal corresponding to the magnitude of the physical quantity and a leakage signal of the vibration based on the drive signal by vibrating based on the drive signal, and the detected signal including the leakage signal. A first synchronous detection circuit for synchronously detecting the detection signal based on a first reference clock;
A second synchronous detection circuit that synchronously detects the leak signal based on a second reference clock for the detected signal;
A phase difference monitoring circuit that monitors a phase difference between the first reference clock and the second reference clock;
Bei to give a,
The phase difference monitoring circuit,
A physical quantity detection circuit comprising: a counter circuit that counts at least one of a high level period and a low level period in an exclusive OR signal of the first reference clock and the second reference clock . The physical quantity detection circuit according to claim 1 ,
The physical quantity detection circuit, wherein the counter circuit counts each of four consecutive periods of the high level period and the low level period in the exclusive OR signal. A physical quantity detecting circuit according to claim 1 or 2,
A physical quantity detection circuit, wherein a clock frequency of the counter circuit is higher than a frequency of the exclusive OR signal. A physical quantity detecting circuit according to any one of claims 1 to 3,
A physical quantity detection circuit further comprising a leak signal monitoring circuit that monitors the leak signal. A physical quantity detecting circuit according to any one of claims 1 to 4,
With a register,
The physical quantity detection circuit, wherein the phase difference monitoring circuit writes error information to the register when determining that the phase difference is abnormal. A physical quantity detecting circuit according to any one of claims 1 to 4,
The physical quantity detection circuit, wherein the phase difference monitoring circuit outputs an error information signal to the outside when it is determined that the phase difference is abnormal. The physical quantity detection circuit according to claim 4 , wherein
A first comparator;
A second comparator;
A control unit;
Further comprising
The control unit includes:
When the first comparator is generating the first reference clock,
A physical quantity for causing the second comparator to generate the first reference clock when it is determined that the monitoring result of the leak signal monitoring circuit is normal and the monitoring result of the phase difference monitoring circuit is abnormal; Detection circuit.   The detection signal from the physical quantity detection element that generates a detection signal corresponding to the magnitude of the physical quantity and a leakage signal of the vibration based on the drive signal by vibrating based on the drive signal, and the detected signal including the leakage signal. A first synchronous detection circuit for synchronously detecting the detection signal based on a first reference clock;
  A second synchronous detection circuit that synchronously detects the leak signal based on a second reference clock for the detected signal;
  A phase difference monitoring circuit that monitors a phase difference between the first reference clock and the second reference clock;
  A leak signal monitoring circuit for monitoring the leak signal,
  A first comparator;
  A second comparator;
  A control unit;
  With
  The control unit includes:
  When the first comparator is generating the first reference clock,
  When the monitoring result of the leak signal monitoring circuit is normal and the monitoring result of the phase difference monitoring circuit is determined to be abnormal, the second comparator generates the first reference clock. circuit.   An electronic device comprising the physical quantity detection circuit according to claim 1.   A moving object comprising the physical quantity detection circuit according to claim 1.

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