JP2022099492A - Physical quantity detection device and fault diagnosis method for physical quantity detection device - Google Patents

Abstract

To provide a physical quantity detection device that can reduce the influence of noise caused by vibration leakage and perform fault diagnosis of a vibration element.SOLUTION: A physical quantity detection device comprises: a vibration element that has a first electrode provided on a first vibration arm and a second electrode provided on a second vibration arm; a driving circuit; a detection circuit; a fault diagnosis circuit; and a switching circuit that, in a first mode, electrically connects the first electrode and the detection circuit to each other and electrically connects the second electrode and the driving circuit to each other, and in a second mode, electrically connects the first electrode and the driving circuit or the fault diagnosis circuit to each other. In the second mode, the driving circuit applies a driving signal to the first electrode and subsequently stops the application of the driving signal. In the second mode, the fault diagnosis circuit performs fault diagnosis of the vibration element based on an output signal from the first electrode after a predetermined time from when the application of the driving signal is stopped.SELECTED DRAWING: Figure 9

Description

The present invention relates to a physical quantity detecting device and a method for diagnosing a failure of the physical quantity detecting device.

Currently, in various systems and electronic devices, physical quantity detection devices capable of detecting various physical quantities, such as a gyro sensor for detecting an angular velocity and an acceleration sensor for detecting an acceleration, are widely used. In recent years, in particular, in order to construct a highly reliable system, a physical quantity detection device that diagnoses a failure of a vibrating element or the like that detects a physical quantity has been used.

For example, in Patent Document 1, frequency tuning is performed on the vibrating element so that the driving vibration leaks to the detection electrode in the vibrating element, and the magnitude of the vibration leakage component when a failure such as disconnection occurs in the vibrating element. Described is an angular velocity detection device that determines a failure of a vibrating element by utilizing the change in frequency.

Japanese Unexamined Patent Publication No. 2010-10716

In the angular velocity detection device described in Patent Document 1, a vibration leakage component having a certain size is required for reliable failure determination, but the vibration leakage component becomes a noise component with respect to the detected angular velocity component. Therefore, the S / N ratio of the angular velocity detection may deteriorate.

One aspect of the physical quantity detecting device according to the present invention is
A vibrating element having a piezoelectric body including a first vibrating arm and a second vibrating arm, a first electrode provided on the first vibrating arm, and a second electrode provided on the second vibrating arm.
A drive circuit that applies a drive signal to the vibrating element,
A detection circuit that generates a physical quantity detection signal according to the physical quantity detected by the vibrating element based on the output signal from the first electrode.
A failure diagnosis circuit that diagnoses the failure of the vibrating element and
In the first mode, the first electrode is electrically connected to the detection circuit, the second electrode is electrically connected to the drive circuit, and in the second mode, the first electrode is connected to the drive circuit or the drive circuit or the drive circuit. Equipped with a failure diagnosis circuit and a switching circuit that electrically connects,
In the second mode, the drive circuit applies the drive signal to the first electrode and then stops applying the drive signal to the first electrode.
In the second mode, the failure diagnosis circuit vibrates based on the output signal from the first electrode after a predetermined time after the drive circuit stops applying the drive signal to the first electrode. Perform element failure diagnosis.

One aspect of the failure diagnosis method of the physical quantity detecting device according to the present invention is
A vibrating element having a piezoelectric body including a first vibrating arm and a second vibrating arm, a first electrode provided on the first vibrating arm, and a second electrode provided on the second vibrating arm.
A drive circuit that applies a drive signal to the vibrating element,
A detection circuit that generates a physical quantity detection signal according to the physical quantity detected by the vibrating element based on the output signal from the first electrode.
It is a failure diagnosis method of a physical quantity detection device equipped with
The step of applying the drive signal to the first electrode and
The step of stopping the application of the drive signal to the first electrode, and
A step of performing a failure diagnosis of the vibrating element based on an output signal from the first electrode after a predetermined time after stopping the application of the drive signal to the first electrode is included.

The figure which shows the structural example of the physical quantity detection apparatus. The plan view which shows the vibrating element schematically. The plan view which shows the vibrating element schematically. The figure for demonstrating the operation of a vibrating element. The figure for demonstrating the operation of a vibrating element. The figure which shows the structural example of the voltage determination circuit. The figure which shows the relationship between the failure content and the electric charge generated in the detection electrode. The figure which shows the state of each switch of a fault diagnosis mode. The figure which shows the state of each switch of a fault diagnosis mode. The figure which shows the state of each switch of a fault diagnosis mode. The figure which shows the state of each switch of a fault diagnosis mode. The figure which shows an example of the waveform of various signals of a fault diagnosis mode. The flowchart which shows an example of the procedure of the failure diagnosis method.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unreasonably limit the content of the present invention described in the claims. Moreover, not all of the configurations described below are essential constituent requirements of the present invention.

In the following, a physical quantity detecting device that detects an angular velocity as a physical quantity, that is, an angular velocity detecting device will be described as an example.

1. 1. The first embodiment is a functional block diagram of the physical quantity detection device of the present embodiment. The physical quantity detection device 1 of the present embodiment includes a vibration element 100 and a physical quantity detection circuit 200.

The physical quantity detection circuit 200 has DS terminal, DG terminal, S1G terminal, S2G terminal, S1 terminal, S2 terminal, CTL terminal, DIAG terminal, SS terminal, SCK terminal, SI terminal, SO terminal, and VO terminal as external connection terminals. Have. The DS terminal, DG terminal, S1G terminal, S2G terminal, S1 terminal and S2 terminal are electrically connected to the vibrating element 100. Further, the CTL terminal, DIAG terminal, SS terminal, SCK terminal, SI terminal, SO terminal, and VO terminal are electrically connected to an external device (not shown).

2 and 3 are plan views schematically showing the vibration element 100. In addition, in FIGS. 2 and 3, as three axes orthogonal to each other, the X axis which is the first axis, the Y axis which is the second axis, and the Z axis which is the third axis are illustrated.

Note that FIG. 2 is a view of the vibrating element 100 as viewed from the first main surface 2a side, and is a diagram for explaining the configuration of the first main surface 2a side. FIG. 3 is a perspective view of the vibrating element 100 as viewed from the first main surface 2a side, and is a diagram for explaining the configuration of the second main surface 2b side.

As shown in FIGS. 2 and 3, the vibrating element 100 includes a base 10, connecting arms 110, 112, driving vibrating arms 120, 122, 124, 126, detected vibrating arms 130, 132, and a support portion 140. 142, beam portions 150, 152, 154, 156, drive input electrode 30, drive output electrode 32, first detection electrode 40, second detection electrode 42, third detection electrode 44, and fourth detection. It includes an electrode 46, a drive input wiring 50, a drive output wiring 52, a first detection wiring 60, a second detection wiring 62, a third detection wiring 64, and a fourth detection wiring 66.

The base 10, connecting arms 110, 112, drive vibrating arms 120, 122, 124, 126, detected vibrating arms 130, 132, support portions 140, 142 and beam portions 150, 152, 154, 156 constitute the piezoelectric body 101. ing. That is, the piezoelectric body 101 includes connecting arms 110, 112, driving vibrating arms 120, 122, 124, 126, detected vibrating arms 130, 132, support portions 140, 142, and beam portions 150, 152, 154, 156. The material of the piezoelectric body 101 is, for example, quartz, lithium tantalate, lithium niobate, or the like. The piezoelectric body 101 has a first main surface 2a and a second main surface 2b facing in opposite directions, and a side surface 3 connected to the main surfaces 2a and 2b. In the illustrated example, the first main surface 2a is a surface facing the + Z axis direction, the second main surface 2b is a surface facing the −Z axis direction, and the side surface 3 is a surface whose perpendicular line is orthogonal to the Z axis. Is. The main surfaces 2a and 2b are, for example, flat surfaces. The thickness direction of the piezoelectric body 101 is along the Z-axis direction, and for example, the thickness of the piezoelectric body 101 is about 100 μm.

The base 10 has a center point G. The position of the center point G is the position of the center of gravity of the piezoelectric body 101. The planar shape of the base 10 is, for example, a rectangle.

The first connecting arm 110 and the second connecting arm 112 extend from the base 10 in opposite directions along the X axis. In the illustrated example, the first connecting arm 110 extends from the base 10 in the −X axis direction, and the second connecting arm 112 extends from the base 10 in the + X axis direction.

The first drive vibrating arm 120 and the second drive vibrating arm 122 extend from the tip of the first connecting arm 110 in opposite directions along the Y axis. In the illustrated example, the first drive vibrating arm 120 extends from the first connecting arm 110 in the + Y axis direction, and the second drive vibrating arm 122 extends from the first connecting arm 110 in the −Y axis direction. The drive vibrating arms 120 and 122 are connected to the base 10 via the first connecting arm 110.

The third drive vibrating arm 124 and the fourth drive vibrating arm 126 extend from the tip of the second connecting arm 112 in opposite directions along the Y axis. In the illustrated example, the third drive vibrating arm 124 extends from the second connecting arm 112 in the + Y axis direction, and the fourth drive vibrating arm 126 extends from the second connecting arm 112 in the −Y axis direction. The drive vibrating arms 124 and 126 are connected to the base 10 via the second connecting arm 112.

The first detected vibrating arm 130 and the second detected vibrating arm 132 extend from the base 10 in opposite directions along the Y axis. In the illustrated example, the first detection vibrating arm 130 extends from the base 10 in the + Y-axis direction, and the second detection vibrating arm 132 extends from the base 10 in the −Y-axis direction. The detection vibrating arms 130 and 132 are connected to the base 10.

A wide portion 5 is provided at the tip of the vibrating arm 120, 122, 124, 126, 130, 132. The wide portion 5 has a larger width (magnitude in the X-axis direction) than the other portions of the vibrating arms 120, 122, 124, 126, 130, and 132. Although not shown, the wide portion 5 may be provided with a weight portion. By adjusting the mass of the weight portion, the vibration frequency of the vibrating arm 120, 122, 124, 126, 130, 132 can be adjusted.

The first support portion 140 is provided on the + Y-axis direction side with respect to the vibrating arms 120, 124, 130. The second support portion 142 is provided on the −Y axis direction side with respect to the vibrating arms 122, 126, 132. The support portions 140 and 142 are portions fixed to the package when the vibrating element 100 is mounted. The support portions 140 and 142 support the base portion 10 via the beam portions 150, 152, 154 and 156.

The first beam portion 150 and the second beam portion 152 connect the base portion 10 and the first support portion 140. In the illustrated example, the first beam portion 150 extends from the base portion 10 to the first support portion 140 through between the first drive vibrating arm 120 and the first detected vibrating arm 130. The second beam portion 152 extends from the base portion 10 to the first support portion 140 through between the third drive vibrating arm 124 and the first detected vibrating arm 130.

The third beam portion 154 and the fourth beam portion 156 connect the base portion 10 and the second support portion 142. In the illustrated example, the third beam portion 154 extends from the base portion 10 through between the second drive vibrating arm 122 and the second detected vibrating arm 132 to the second support portion 142. The fourth beam portion 156 extends from the base portion 10 to the second support portion 142 through between the fourth drive vibrating arm 126 and the second detected vibrating arm 132.

The beam portions 150, 152, 154, and 156 have a substantially S-shaped portion in a plan view. Therefore, the beam portions 150, 152, 154, and 156 can have high elasticity. As a result, the support portions 140, 142 support the base portion 10 via the beam portions 150, 152, 154, 156 without disturbing the vibration of the vibrating arms 120, 122, 124, 126, 130, 132. Can be done.

In the vibrating element 100 according to the present embodiment, as shown in FIGS. 2 and 3, the piezoelectric body 101 is a so-called double T-shaped vibrating piece.

Drive input electrode 30, drive output electrode 32, first detection electrode 40, second detection electrode 42, third detection electrode 44, fourth detection electrode 46, drive input wiring 50, drive output wiring 52, first detection wiring 60, As the second detection wiring 62, the third detection wiring 64, and the fourth detection wiring 66, for example, those laminated in the order of chromium and gold from the piezoelectric body 101 side are used.

The drive input electrode 30 is provided on the drive vibrating arm 120, 122, 124, 126. In the illustrated example, the drive input electrode 30 is the side surface 3 and the wide portion 5 of the first drive vibrating arm 120, the side surface 3 and the wide portion 5 of the second drive vibrating arm 122, and the main surface of the third drive vibrating arm 124. It is provided on 2a and 2b and on the main surfaces 2a and 2b of the fourth drive vibrating arm 126. The drive input electrode 30 is arranged symmetrically with respect to a plane passing through the center point G and parallel to the XZ plane, for example. The drive input electrode 30 is an electrode to which a drive signal for driving the drive vibrating arms 120, 122, 124, 126 is input.

The drive output electrode 32 is provided on the drive vibrating arm 120, 122, 124, 126. In the illustrated example, the drive output electrode 32 has a main surface 2a, 2b of the first drive vibrating arm 120, a main surface 2a, 2b of the second drive vibrating arm 122, a side surface 3 of the third drive vibrating arm 124, and a wide width. The portion 5 is provided on the side surface 3 and the wide portion 5 of the fourth drive vibrating arm 126. The drive output electrode 32 is arranged symmetrically with respect to a plane passing through the center point G and parallel to the XZ plane, for example. The drive output electrode 32 is an electrode for outputting a signal based on the bending of the drive vibrating arms 120, 122, 124, 126.

Although not shown, the drive output electrode 32 may be provided at a position where the drive input electrode 30 is provided, and the drive input electrode 30 is provided at a position where the drive output electrode 32 is provided. May be good.

The first detection electrode 40 is provided on the first detection vibration arm 130. In the illustrated example, the first detection electrode 40 is provided on the main surfaces 2a and 2b of the first detection vibration arm 130. The first detection electrode 40 is an electrode for outputting a signal based on the bending of the first detection vibration arm 130.

The second detection electrode 42 is provided on the second detection vibration arm 132. In the illustrated example, the second detection electrode 42 is provided on the main surfaces 2a and 2b of the second detection vibration arm 132. The second detection electrode 42 is arranged symmetrically with respect to the first detection electrode 40 and the plane passing through the center point G and parallel to the XZ plane, for example. The second detection electrode 42 is an electrode for outputting a signal based on the bending of the second detection vibration arm 132.

The third detection electrode 44 is provided on the first detection vibration arm 130. In the illustrated example, the third detection electrode 44 is provided on the side surface 3 and the wide portion 5 of the first detection vibration arm 130. The third detection electrode 44 is an electrode to which a reference ground voltage GND is applied to the signal output from the first detection electrode 40. For example, the ground voltage GND is a voltage that is ½ of the power supply voltage supplied to the physical quantity detection circuit 200.

The fourth detection electrode 46 is provided on the second detection vibration arm 132. In the illustrated example, the fourth detection electrode 46 is provided on the side surface 3 and the wide portion 5 of the second detection vibration arm 132. The fourth detection electrode 46 is arranged symmetrically with respect to the third detection electrode 44 and the plane passing through the center point G and parallel to the XZ plane, for example. The fourth detection electrode 46 is an electrode to which a reference ground voltage GND is applied to the signal output from the second detection electrode 42.

The drive input wiring 50 is provided in the base portion 10, the connecting arms 110 and 112, the second support portion 142, and the third beam portion 154. In the illustrated example, the drive input wiring 50 is the first main surface 2a and the side surface 3 of the base 10, the first main surface 2a of the first connecting arm 110, and the main surfaces 2a, 2b and the side surface of the second connecting arm 112. 3 is provided on the main surfaces 2a and 2b and the side surface 3 of the second support portion 142, and the side surface 3 of the third beam portion 154. The drive input electrodes 30 provided on the vibrating arms 120, 122, 124, 126 are electrically connected to each other by the drive input wiring 50. The drive input wiring 50 provided in the second support portion 142 is a terminal portion 50a. In the illustrated example, the planar shape of the terminal portion 50a is rectangular. The terminal portion 50a is connected to an external member (not shown), for example, a bonding wire, and is electrically connected to the DS terminal of the physical quantity detection circuit 200 via the external member and the drive input wiring 50.

The drive output wiring 52 is provided on the base portion 10, the connecting arms 110 and 112, the first support portion 140, and the first beam portion 150. In the illustrated example, the drive output wiring 52 is the second main surface 2b of the base 10, the main surfaces 2a and 2b and the side surface 3 of the first connecting arm 110, and the second main surface 2b and the side surface of the second connecting arm 112. 3 is provided on the main surfaces 2a and 2b and the side surface 3 of the first support portion 140, and the second main surface 2b and the side surface 3 of the first beam portion 150. The drive output electrodes 32 provided on the vibrating arms 120, 122, 124, 126 are electrically connected to each other by the drive output wiring 52. The drive output wiring 52 provided in the first support portion 140 is a terminal portion 52a. In the illustrated example, the planar shape of the terminal portion 52a is rectangular. The terminal portion 52a is connected to an external member, for example, a bonding wire, and is electrically connected to the DG terminal of the physical quantity detection circuit 200 via the drive output wiring 52 and the external member.

The first detection wiring 60 is provided in the base portion 10, the first support portion 140, and the second beam portion 152. In the illustrated example, the first detection wiring 60 includes the main surfaces 2a and 2b of the base 10, the main surfaces 2a and 2b and the side surface 3 of the first support portion 140, and the first main surface 2a and the second beam portion 152. It is provided on the side surface 3. The first detection wiring 60 is connected to the first detection electrode 40. The first detection wiring 60 provided in the first support portion 140 is a terminal portion 60a. In the illustrated example, the planar shape of the terminal portion 60a is rectangular. The terminal portion 60a is connected to an external member, for example, a bonding wire, and is electrically connected to the S1 terminal of the physical quantity detection circuit 200 via the first detection wiring 60 and the external member.

The second detection wiring 62 is provided in the base portion 10, the second support portion 142, and the fourth beam portion 156. In the illustrated example, the second detection wiring 62 includes the main surfaces 2a and 2b of the base 10, the main surfaces 2a and 2b and the side surface 3 of the second support portion 142, and the first main surface 2a and the fourth beam portion 156. It is provided on the side surface 3. The second detection wiring 62 is connected to the second detection electrode 42. The second detection wiring 62 provided in the second support portion 142 is a terminal portion 62a. In the illustrated example, the planar shape of the terminal portion 62a is rectangular. The terminal portion 62a is connected to an external member, for example, a bonding wire, and is electrically connected to the S2 terminal of the physical quantity detection circuit 200 via the second detection wiring 62 and the external member.

The third detection wiring 64 is provided in the base portion 10, the first support portion 140, and the second beam portion 152. In the illustrated example, the third detection wiring 64 includes the main surfaces 2a, 2b and the side surface 3 of the base 10, the main surfaces 2a, 2b and the side surface 3 of the first support portion 140, and the main surface 2a of the second beam portion 152. , 2b and side surface 3 and. The third detection wiring 64 is connected to the third detection electrode 44. The third detection wiring 64 provided in the first support portion 140 is a terminal portion 64a. In the illustrated example, the planar shape of the terminal portion 64a is rectangular. The terminal portion 64a is connected to an external member, for example, a bonding wire, and is electrically connected to the S1G terminal of the physical quantity detection circuit 200 via the third detection wiring 64 and the external member.

The fourth detection wiring 66 is provided in the base portion 10, the second support portion 142, and the fourth beam portion 156. In the illustrated example, the fourth detection wiring 66 has a main surface 2a, 2b and a side surface 3 of the base 10, a main surface 2a, 2b and a side surface 3 of the second support portion 142, and a main surface 2a of the fourth beam portion 156. , 2b and side surface 3 and. The fourth detection wiring 66 is connected to the fourth detection electrode 46. The fourth detection wiring 66 provided in the second support portion 142 is a terminal portion 66a. In the illustrated example, the planar shape of the terminal portion 66a is rectangular. The terminal portion 66a is connected to an external member, for example, a bonding wire, and is electrically connected to the S2G terminal of the physical quantity detection circuit 200 via the fourth detection wiring 66 and the external member.

In FIGS. 2 and 3, the electrodes 30, 32, 40, 42, 44, 46 and the wirings 50, 52, 60, 62, 64, 66 provided on the side surface 3 of the piezoelectric body 101 are shown by thick lines. There is.

4 and 5 are plan views for explaining the operation of the vibrating element 100. For convenience, in FIGS. 4 and 5, members other than the base 10, connecting arms 110 and 112, and vibrating arms 120, 122, 124, 126, 130 and 132 are not shown.

As shown in FIG. 4, the vibrating element 100 has an XY plane when a predetermined AC voltage is applied to the drive input electrodes 30 provided on the drive vibrating arms 120, 122, 124, 126 in a state where the angular velocity is not applied. Bending vibration is performed in the direction of arrow A. The mode of the vibrating element 100 is called "vibration mode". At this time, the drive vibrating arms 120, 122 and the drive vibrating arms 124, 126 vibrate plane-symmetrically with respect to a plane passing through the center point G and parallel to the YZ plane. Therefore, the base 10, the connecting arms 110 and 112, and the detected vibrating arms 130 and 132 hardly vibrate.

When the angular velocity ω around the Z axis is applied to the vibrating element 100 in a state where the driving vibrating arms 120, 122, 124, 126 are performing such driving vibration, as shown in FIG. 5, the driving vibrating arms 120, 122 Coriolis force acts on, 124, 126. As a result, the drive vibrating arms 120, 122, 124, 126 vibrate in the direction of arrow B. The vibration in the direction of the arrow B is a vibration in the circumferential direction with respect to the center point G. Then, the connecting arms 110 and 112 vibrate in the direction of the arrow B due to the vibration of the drive vibrating arms 120, 122, 124 and 126. This vibration is transmitted to the detected vibrating arms 130 and 132 via the base 10, and the detected vibrating arms 130 and 132 are vibrated as shown by the arrow C. The vibration in the direction of the arrow C is the vibration in the direction opposite to that of the arrow B with respect to the center point G. The mode of the vibrating element 100 is called "detection mode". The potential difference generated between the first detection electrode 40 and the third detection electrode 44 and the potential difference generated between the second detection electrode 42 and the fourth detection electrode 46 due to the bending vibration of the detection vibration arms 130 and 132. By detecting, the angular velocity around the Z axis can be obtained.

If the drive vibration of the drive vibration arms 120, 122, 124, 126 leaks to the first detection electrode 40 and the second detection electrode 42, it becomes a noise component for the angular velocity component, but the vibration arms 120, 122, 124, 126, 130. By appropriately adjusting the mass of the weight portion (not shown) provided in the wide portion 5 of the 132, the drive vibrations leaking from the drive vibration arms 120, 122, 124, 126 are canceled each other at the base 10.

Returning to the description of FIG. 1, the physical quantity detection circuit 200 includes a drive circuit 210, a detection circuit 220, a voltage determination circuit 230A, a voltage determination circuit 230B, a failure diagnosis circuit 240, a control circuit 250, a storage unit 260, an interface circuit 270, and a switching circuit. 280 is provided. The physical quantity detection circuit 200 may be realized by an integrated circuit of one chip, or may be realized by combining an integrated circuit of a plurality of chips or a discrete component.

The physical quantity detection device 1 has a start mode, a normal operation mode, and a failure diagnosis mode as operation modes. The start mode is an operation mode from when the power is turned on to the physical quantity detection device 1 until the transition to the normal operation mode. The normal operation mode is a mode for detecting a physical quantity applied to the vibrating element 100. The failure diagnosis mode is a mode for diagnosing a failure of the vibrating element 100. The states of 281 to 287 included in the switching circuit 280 are different between the start mode and the normal operation mode and the failure diagnosis mode. FIG. 1 shows the states of the switches 281 to 287 in the start mode and the normal operation mode. First, the operation of the physical quantity detection circuit 200 in the start mode and the normal operation mode will be described.

The switching circuit 280 electrically connects the drive input electrode 30 of the vibration element 100 to the drive circuit 210 in the start mode and the normal operation mode, and detects the first detection electrode 40 and the second detection electrode 42 of the vibration element 100. Electrically connect to 220. Specifically, the switch 281 connects the DS terminal and the AGC circuit 212. The switch 282 connects the S1 terminal and the Q / V conversion circuit 221P. The switch 283 connects the S2 terminal and the Q / V conversion circuit 221N. The switch 284 connects the Q / V conversion circuit 221P and the differential amplifier 222. The switch 285 connects the Q / V conversion circuit 221N and the differential amplifier 222. The switch 286 connects the Q / V conversion circuit 221P and the switch 287. The switch 287 disconnects the switch 286 from the voltage determination circuit 230B.

The drive circuit 210 generates a drive signal and applies the drive signal to the vibrating element 100 via the DS terminal. In this embodiment, the drive circuit 210 includes an I / V conversion circuit 211, an AGC circuit 212, a comparator 213 and a start circuit 214. AGC is an abbreviation for Automatic Gain Control.

When the power is turned on to the physical quantity detection device 1, the start mode in which the start circuit 214 operates starts. The activation circuit 214 self-oscillates at a frequency close to the resonance frequency of the vibrating element 100, and outputs an oscillation signal. The starting circuit 214 can be realized by, for example, a CR oscillation circuit or the like. The oscillation signal output from the start circuit 214 is applied to the drive input electrode 30 of the vibration element 100 via the AGC circuit 212, the switch 281 and the DS terminal, and the vibration element 100 starts vibration.

When the vibrating element 100 vibrates, an alternating current based on the piezoelectric effect is output from the drive output electrode 32, and the alternating current is input to the I / V conversion circuit 211 via the DG terminal. The I / V conversion circuit 211 converts the input AC current into an AC voltage signal having the same frequency as the vibration frequency of the vibrating element 100 and outputs it.

With the passage of time, the vibration of the vibrating element 100 increases, and the amplitude of the AC voltage signal output from the I / V conversion circuit 211 increases. Then, when the vibration of the vibrating element 100 becomes stable and the amplitude of the AC voltage signal output from the I / V conversion circuit 211 becomes substantially constant, the start circuit 214 stops operating and the operation mode of the physical quantity detection device 1 starts. The mode shifts to the normal operation mode. For example, the starting circuit 214 may voluntarily stop the operation after a predetermined time has elapsed from the start of the operation of the starting circuit 214 until the vibration of the vibrating element 100 stabilizes. Alternatively, when the amplitude detection circuit (not shown) detects that the amplitude of the AC voltage signal output from the I / V conversion circuit 211 has reached a predetermined value, the operation of the start circuit 214 may be stopped.

In the normal operation mode, the AC voltage signal output from the I / V conversion circuit 211 is input to the AGC circuit 212 and the comparator 213.

The AGC circuit 212 amplifies the input AC voltage signal and controls the gain of the amplification to generate a drive signal whose amplitude is maintained at a constant voltage. This drive signal is applied to the drive input electrode 30 of the vibrating element 100 via the switch 281 and the DS terminal, and the vibrating element 100 continues stable vibration.

The comparator 213 amplifies the AC voltage signal output from the I / V conversion circuit 211, and outputs a square wave voltage signal which is a binarized signal.

As described above, the drive circuit 210 generates a drive signal based on the output signal from the drive output electrode 32 of the vibration element 100 in the normal operation mode, and applies the drive signal to the drive input electrode 30 of the vibration element 100. ..

The detection circuit 220 generates a physical quantity detection signal according to the physical quantity detected by the vibrating element 100 based on the signal input via the S1 terminal and the signal input via the S2 terminal in the normal operation mode. .. That is, the detection circuit 220 generates a physical quantity detection signal based on the output signal from the first detection electrode 40 and the output signal from the second detection electrode 42 in the normal operation mode. In the present embodiment, since the vibrating element 100 detects the angular velocity as a physical quantity, the detection circuit 220 generates an angular velocity signal corresponding to the angular velocity as the physical quantity detection signal. In the present embodiment, the detection circuit 220 includes a Q / V conversion circuit 221P, a Q / V conversion circuit 221N, a differential amplifier 222, a high-pass filter 223, an AC amplifier 224, a synchronous detection circuit 225, a sensitivity adjustment amplifier 226, and a switched capacitor filter. 227 and ratiometric amplifier 228 are included.

The AC charge, which is an output signal from the first detection electrode 40 of the vibrating element 100, is input to the Q / V conversion circuit 221P via the S1 terminal and the switch 282. The Q / V conversion circuit 221P converts the input AC charge into an AC voltage signal.

The AC charge, which is an output signal from the second detection electrode 42 of the vibrating element 100, is input to the Q / V conversion circuit 221N via the S2 terminal and the switch 283. The Q / V conversion circuit 221N converts the input AC charge into an AC voltage signal.

The differential amplifier 222 differentially amplifies the output signal of the Q / V conversion circuit 221P input via the switch 284 and the output signal of the Q / V conversion circuit 221N input via the switch 285.

The high-pass filter 223 attenuates the DC component contained in the output signal of the differential amplifier 222.

The AC amplifier 224 amplifies the output signal of the high-pass filter 223.

The synchronous detection circuit 225 extracts the signal component of the physical quantity detected by the vibrating element 100 by synchronously detecting the output signal of the AC amplifier 224 using the square wave voltage signal output from the comparator 213 as the detection signal.

The sensitivity adjustment amplifier 226 amplifies or attenuates the output signal of the synchronous detection circuit 225 with a set gain, and adjusts the detection sensitivity of the physical quantity.

The switched capacitor filter 227 filters the output signal of the sensitivity adjustment amplifier 226 to attenuate the high frequency noise component.

The ratiometric amplifier 228 amplifies or attenuates the output signal of the switched capacitor filter 227 with a gain corresponding to the power supply voltage, and changes the zero point voltage and the detection sensitivity in proportion to the power supply voltage. Then, the output signal of the ratiometric amplifier 228 is output as a physical quantity detection signal to an external device (not shown) via the VO terminal.

The voltage determination circuit 230A outputs a voltage determination signal indicating whether or not the voltage level of the drive signal output from the AGC circuit 212 is normal. FIG. 6 shows a configuration example of the voltage determination circuit 230A. In the example of FIG. 6, the voltage determination circuit 230A includes an AC amplifier 231, a rectifier circuit 232, a smoothing circuit 233, and a comparison circuit 234. The signal input to the voltage determination circuit 230A is amplified by the AC amplifier 231, full-wave rectified by the rectifier circuit 232, and further smoothed by the smoothing circuit 233. The comparison circuit 234 determines whether or not the voltage of the signal smoothed by the smoothing circuit 233 is included in a predetermined range, and outputs a voltage determination signal indicating the determination result. For example, the comparison circuit 234 becomes low level when the voltage of the signal smoothed by the smoothing circuit 233 is included in the predetermined range, and the voltage of the signal smoothed by the smoothing circuit 233 is included in the predetermined range. If not, a high level voltage judgment signal is output.

The failure diagnosis circuit 240 performs failure diagnosis of the drive circuit 210 based on the voltage determination signal output from the voltage determination circuit 230A in the normal operation mode, and becomes a high level failure diagnosis when the drive circuit 210 is a failure. Output a signal. Specifically, in the normal operation mode, when the voltage determination signal output from the voltage determination circuit 230A reaches a high level, the failure diagnosis circuit 240 fixes the failure diagnosis signal to a high level and stores it in the storage unit 260. Write 1 to the drive failure flag among the plurality of failure flags. The failure diagnosis signal is output to an external device (not shown) via the DIAG terminal.

Here, the failure diagnosis circuit 240 performs failure diagnosis of the drive circuit 210 based on the voltage determination signal output from the voltage determination circuit 230A, but the voltage determination signal output from the voltage determination circuit 230A is a drive signal. It is a signal indicating whether it is normal or not. That is, in the present embodiment, the failure diagnosis circuit 240 performs failure diagnosis of the drive circuit 210 based on the drive signal.

The interface circuit 270 performs a process of reading data stored in the storage unit 260 and outputting the data to the external device in response to a request from an external device (not shown), and a process of writing the data input from the external device to the storage unit 260. conduct. For example, when the failure diagnosis signal output from the DIAG terminal changes from low level to high level, the external device reads out a plurality of failure flags stored in the storage unit 260 via the interface circuit 270, and drives the drive failure flag. If is 1, it can be determined that the drive circuit 210 is out of order. The interface circuit 270 is, for example, an interface circuit of an SPI bus, and a selection signal, a clock signal, and a data signal transmitted from an external device are input via an SS terminal, an SCK terminal, and an SI terminal, respectively, and an SO terminal is used. The data signal is output to an external device via the device. SPI is an abbreviation for Serial Peripheral Interface. The interface circuit 270 may be an interface circuit corresponding to various buses other than the SPI bus, for example, an ^I2C bus. I ^2C is an abbreviation for Inter-Integrated Circuit.

Next, the operation of the physical quantity detection circuit 200 in the failure diagnosis mode will be described. In the present embodiment, in the normal operation mode, the physical quantity detection device 1 is set to the failure diagnosis mode when a static signal indicating that the physical quantity detection device 1 is stationary is input to the CTL terminal from an external device (not shown). Transition. Specifically, the control circuit 250 switches the operation mode of the physical quantity detection device 1 to the failure diagnosis mode when a static signal is input to the CTL terminal. For example, the control circuit 250 switches the operation mode to the failure diagnosis mode when a low-level stationary signal is continuously input to the CTL terminal for a predetermined time. When the physical quantity detection device 1 is mounted on a vehicle, the stationary signal may be a vehicle speed pulse signal. Further, the control circuit 250 may switch the operation mode of the physical quantity detection device 1 from the activation mode to the failure diagnosis mode, and further switch from the failure diagnosis mode to the normal operation mode.

The physical quantity detection circuit 200 performs a failure diagnosis of the first detection electrode 40 of the vibrating element 100 and a failure diagnosis of the second detection electrode 42 in the failure diagnosis mode. Specifically, the physical quantity detection circuit 200 applies a drive signal to the first detection electrode 40 and excites the detection mode shown in FIG. 5 to the vibrating element 100 in order to perform a failure diagnosis of the first detection electrode 40. do. After that, the physical quantity detection circuit 200 stops applying the drive signal to the first detection electrode 40, and the first detection electrode 40 is based on the electric charge generated in the first detection electrode 40 a predetermined time after the application of the drive signal is stopped. Failure diagnosis of the detection electrode 40 can be performed. Similarly, the physical quantity detection circuit 200 stops applying the drive signal to the second detection electrode 42 after applying the drive signal to the second detection electrode 42, and after a predetermined time after stopping the application of the drive signal, the second is performed. 2. Failure diagnosis of the second detection electrode 42 can be performed based on the electric charge generated in the detection electrode 42.

FIG. 7 shows the relationship between the details of the failure of the first detection electrode 40 and the electric charge generated in the first detection electrode 40 after a predetermined time after the application of the drive signal is stopped, and the details of the failure of the second detection electrode 42 and the drive signal. The relationship with the electric charge generated in the second detection electrode 42 after a predetermined time after the application is stopped is shown. As shown in FIG. 7, when a drive signal is applied to the first detection electrode 40, if there is an open or short failure in the first detection electrode 40, the drive signal is not correctly applied to the first detection electrode 40. If no charge is generated and the first detection electrode 40 has a peeling failure, the resistance value rises and the drive signal applied to the first detection electrode 40 is attenuated, so that the charge generated in the first detection electrode 40 Is smaller than normal. Therefore, the physical quantity detection circuit 200 stops applying the drive signal to the first detection electrode 40 after applying the drive signal to the first detection electrode 40, and after a predetermined time, the charge is output from the first detection electrode 40. Based on this, failure diagnosis of the first detection electrode 40 can be performed.

Similarly, when a drive signal is applied to the second detection electrode 42, if there is an open or short failure in the second detection electrode 42, the drive signal is not applied correctly, so that almost no electric charge is generated in the second detection electrode 42. However, if the second detection electrode 42 has a peeling failure, the resistance value rises and the drive signal applied to the second detection electrode 42 is attenuated. Therefore, the electric charge generated in the second detection electrode 42 is higher than that in the normal state. Also becomes smaller. Therefore, the physical quantity detection circuit 200 stops applying the drive signal to the second detection electrode 42 after applying the drive signal to the second detection electrode 42, and after a predetermined time, the charge is output from the second detection electrode 42. Based on this, failure diagnosis of the second detection electrode 42 can be performed.

The switching circuit 280 electrically connects the first detection electrode 40 to the drive circuit 210 or the failure diagnosis circuit 240 in order to perform a failure diagnosis of the first detection electrode 40 in the failure diagnosis mode. 8 and 9 show the states of the switches 281 to 287 when the failure diagnosis of the first detection electrode 40 is performed in the failure diagnosis mode.

First, as shown in FIG. 8, the switching circuit 280 electrically connects the first detection electrode 40 to the drive circuit 210. Specifically, the switch 281 connects the switches 282, 283 and the AGC circuit 212. The switch 282 connects the S1 terminal and the switch 281. The switch 283 connects the S2 terminal and the Q / V conversion circuit 221N. The switch 284 connects the supply line of the ground voltage GND to the differential amplifier 222. The switch 285 connects the supply line of the ground voltage GND to the differential amplifier 222. The switch 286 connects the Q / V conversion circuit 221P and the switch 287. The switch 287 disconnects the switch 286 from the voltage determination circuit 230B.

The drive circuit 210 generates a drive signal in the failure diagnosis mode, and applies the drive signal to the first detection electrode 40 without applying the drive signal to the drive input electrode 30 of the vibrating element 100. Specifically, in the failure diagnosis mode, the start circuit 214 operates, and the oscillation signal output from the start circuit 214 is the first detection electrode of the vibration element 100 via the AGC circuit 212, the switches 281,282, and the S1 terminal. It is applied to 40, and the detection mode is excited by the vibrating element 100.

Next, as shown in FIG. 9, the switching circuit 280 disconnects the electrical connection between the first detection electrode 40 and the drive circuit 210, and electrically connects the first detection electrode 40 to the failure diagnosis circuit 240. .. Specifically, the switch 281 connects the switches 282, 283 and the AGC circuit 212. The switch 282 connects the S1 terminal and the Q / V conversion circuit 221P. The switch 283 connects the S2 terminal and the Q / V conversion circuit 221N. The switch 284 connects the supply line of the ground voltage GND to the differential amplifier 222. The switch 285 connects the supply line of the ground voltage GND to the differential amplifier 222. The switch 286 connects the Q / V conversion circuit 221P and the switch 287. The switch 287 connects the switch 286 and the voltage determination circuit 230B.

The switch 282 disconnects the electrical connection between the first detection electrode 40 and the drive circuit 210, and stops the application of the drive signal to the first detection electrode 40. That is, in the failure diagnosis mode, the drive circuit 210 stops applying the drive signal to the first detection electrode 40 after applying the drive signal to the first detection electrode 40. Even after the application of the drive signal to the first detection electrode 40 is stopped, the first detection vibrating arm 130 vibrates for a while, and an AC charge is generated in the first detection electrode 40. In particular, if the vibrating element 100 is a crystal vibrating element having a high Q value, the vibration of the first detected vibrating arm 130 does not stop immediately, and the amplitude of the vibration gradually decreases.

The voltage determination circuit 230B receives an output signal of the Q / V conversion circuit 221P via switches 286 and 287, and outputs a voltage determination signal indicating whether or not the voltage level of the output signal of the Q / V conversion circuit 221P is normal. Output. The configuration of the voltage determination circuit 230B is the same as the configuration of the voltage determination circuit 230A shown in FIG.

The failure diagnosis circuit 240 diagnoses the failure of the vibrating element 100 based on the voltage determination signal output from the voltage determination circuit 230B a predetermined time after the electrical connection between the first detection electrode 40 and the drive circuit 210 is disconnected. Is performed, and a failure diagnosis signal that becomes a high level when the vibrating element 100 is a failure is output. Specifically, in the failure diagnosis circuit 240, the voltage determination signal output from the voltage determination circuit 230B after a predetermined time after the electrical connection between the first detection electrode 40 and the drive circuit 210 is disconnected is high. For example, the failure diagnosis signal is fixed at a high level, and 1 is written to the first detection failure flag among the plurality of failure flags stored in the storage unit 260. For example, when the failure diagnosis signal output from the DIAG terminal changes from low level to high level, the external device reads out a plurality of failure flags stored in the storage unit 260 via the interface circuit 270 and performs the first detection. If the failure flag is 1, it can be determined that the first detection electrode 40 is a failure.

Here, the failure diagnosis circuit 240 is based on the voltage determination signal output from the voltage determination circuit 230B after a predetermined time after the electrical connection between the first detection electrode 40 and the drive circuit 210 is disconnected, and the vibration element 100 However, when the electrical connection between the first detection electrode 40 and the drive circuit 210 is cut off, the application of the drive signal to the first detection electrode 40 is stopped. Further, the voltage determination signal output from the voltage determination circuit 230B is a signal indicating whether or not the output signal of the Q / V conversion circuit 221P based on the output signal from the first detection electrode 40 is normal. That is, in the present embodiment, the failure diagnosis circuit 240 outputs from the first detection electrode 40 a predetermined time after the drive circuit 210 stops applying the drive signal to the first detection electrode 40 in the failure diagnosis mode. A failure diagnosis of the vibrating element 100 is performed based on the signal. Further, Q / V when the magnitude of the output signal from the first detection electrode 40 after a predetermined time after the drive circuit 210 stops applying the drive signal to the first detection electrode 40 is in the first range. Assuming that the voltage level of the output signal of the conversion circuit 221P is normal, the failure diagnosis circuit 240 is the first detection electrode after a predetermined time after the drive circuit 210 stops applying the drive signal to the first detection electrode 40. When the magnitude of the output signal from 40 is not included in the first range, the vibrating element 100 is diagnosed as having a failure. The magnitude of the output signal from the first detection electrode 40 is, for example, the average value of the absolute values of the AC charges generated in the first detection electrode 40.

Similarly, the switching circuit 280 electrically connects the second detection electrode 42 to the drive circuit 210 or the failure diagnosis circuit 240 in order to perform the failure diagnosis of the second detection electrode 42 in the failure diagnosis mode. 10 and 11 show the states of the switches 281 to 287 when the failure diagnosis of the second detection electrode 42 is performed in the failure diagnosis mode.

First, as shown in FIG. 10, the switching circuit 280 electrically connects the second detection electrode 42 to the drive circuit 210. Specifically, the switch 281 connects the switches 282, 283 and the AGC circuit 212. The switch 282 connects the S1 terminal and the Q / V conversion circuit 221P. The switch 283 connects the S2 terminal and the switch 281. The switch 284 connects the supply line of the ground voltage GND to the differential amplifier 222. The switch 285 connects the supply line of the ground voltage GND to the differential amplifier 222. The switch 286 connects the Q / V conversion circuit 221N and the switch 287. The switch 287 disconnects the switch 286 from the voltage determination circuit 230B.

The drive circuit 210 generates a drive signal in the failure diagnosis mode, and applies the drive signal to the second detection electrode 42 without applying the drive signal to the drive input electrode 30 of the vibrating element 100. Specifically, the oscillation signal output from the start circuit 214 is applied to the second detection electrode 42 of the vibration element 100 via the AGC circuit 212, the switches 281,283 and the S2 terminal, and the vibration element 100 has a detection mode. Be excited.

Next, as shown in FIG. 11, the switching circuit 280 disconnects the electrical connection between the second detection electrode 42 and the drive circuit 210, and electrically connects the second detection electrode 42 to the failure diagnosis circuit 240. .. Specifically, the switch 281 connects the switches 282, 283 and the AGC circuit 212. The switch 282 connects the S1 terminal and the Q / V conversion circuit 221P. The switch 283 connects the S2 terminal and the Q / V conversion circuit 221N. The switch 284 connects the supply line of the ground voltage GND to the differential amplifier 222. The switch 285 connects the supply line of the ground voltage GND to the differential amplifier 222. The switch 286 connects the Q / V conversion circuit 221N and the switch 287. The switch 287 connects the switch 286 and the voltage determination circuit 230B.

The switch 283 disconnects the electrical connection between the second detection electrode 42 and the drive circuit 210, and stops the application of the drive signal to the second detection electrode 42. That is, in the failure diagnosis mode, the drive circuit 210 stops applying the drive signal to the second detection electrode 42 after applying the drive signal to the second detection electrode 42. Even after the application of the drive signal to the second detection electrode 42 is stopped, the second detection vibrating arm 132 vibrates for a while, and an AC charge is generated in the second detection electrode 42. In particular, if the vibrating element 100 is a crystal vibrating element having a high Q value, the vibration of the second detection vibrating arm 132 does not stop immediately, and the amplitude of the vibration gradually decreases.

The voltage determination circuit 230B receives an output signal of the Q / V conversion circuit 221N via switches 286 and 287, and outputs a voltage determination signal indicating whether or not the voltage level of the output signal of the Q / V conversion circuit 221N is normal. Output.

The failure diagnosis circuit 240 diagnoses the failure of the vibrating element 100 based on the voltage determination signal output from the voltage determination circuit 230B a predetermined time after the electrical connection between the second detection electrode 42 and the drive circuit 210 is disconnected. Is performed, and a failure diagnosis signal that becomes a high level when the vibrating element 100 is a failure is output. Specifically, in the failure diagnosis circuit 240, the voltage determination signal output from the voltage determination circuit 230B after a predetermined time after the electrical connection between the second detection electrode 42 and the drive circuit 210 is disconnected is high. For example, the failure diagnosis signal is fixed at a high level, and 1 is written to the second detection failure flag among the plurality of failure flags stored in the storage unit 260. For example, when the failure diagnosis signal output from the DIAG terminal changes from low level to high level, the external device reads out a plurality of failure flags stored in the storage unit 260 via the interface circuit 270 and performs a second detection. If the failure flag is 1, it can be determined that the second detection electrode 42 is a failure.

Here, the failure diagnosis circuit 240 is based on the voltage determination signal output from the voltage determination circuit 230B after a predetermined time after the electrical connection between the second detection electrode 42 and the drive circuit 210 is disconnected, and the vibration element 100 However, when the electrical connection between the second detection electrode 42 and the drive circuit 210 is cut off, the application of the drive signal to the second detection electrode 42 is stopped. Further, the voltage determination signal output from the voltage determination circuit 230B is a signal indicating whether or not the output signal of the Q / V conversion circuit 221N based on the output signal from the second detection electrode 42 is normal. That is, in the present embodiment, the failure diagnosis circuit 240 outputs from the second detection electrode 42 a predetermined time after the drive circuit 210 stops applying the drive signal to the second detection electrode 42 in the failure diagnosis mode. A failure diagnosis of the vibrating element 100 is performed based on the signal. Further, Q / V when the magnitude of the output signal from the second detection electrode 42 after a predetermined time after the drive circuit 210 stops applying the drive signal to the second detection electrode 42 is in the first range. Assuming that the voltage level of the output signal of the conversion circuit 221N is normal, the failure diagnosis circuit 240 has a second detection electrode after a predetermined time after the drive circuit 210 stops applying the drive signal to the second detection electrode 42. When the magnitude of the output signal from 42 is not included in the first range, the vibrating element 100 is diagnosed as having a failure. The magnitude of the output signal from the second detection electrode 42 is, for example, the average value of the absolute values of the AC charges generated in the second detection electrode 42.

In any of FIGS. 8 to 11, since the ground voltage GND is input to the Q / V conversion circuits 221P and 221N, the physical quantity detection signal output from the detection circuit 220 is a zero point in the failure diagnosis mode. It becomes a voltage.

FIG. 12 is a diagram showing an example of the signal waveform of the S1 terminal or the S2 terminal in the failure diagnosis mode. As shown in FIG. 12, when the first detection electrode 40 is normal, the detection mode is excited to the vibrating element 100 when a drive signal is applied to the S1 terminal. After that, when the application of the drive signal is stopped at time t0, the signal input from the S1 terminal gradually attenuates from the time t0, but the signal input from the S1 terminal also at the time t1 when the predetermined time T has elapsed. Since is oscillating with a constant amplitude, its amplitude level is within a predetermined range. On the other hand, when the first detection electrode 40 is open or short-circuited, the detection mode is hardly excited by the vibrating element 100 even if a drive signal is applied to the S1 terminal, and the first detection electrode 40 is peeled off. In the case of, the vibration element 100 is excited to a detection mode in which the vibration is smaller than in the normal state. Therefore, at time t1, the amplitude level of the signal input from the S1 terminal becomes smaller than that in the normal state, and is out of the predetermined range. The same applies to the signal waveform of the S2 terminal when the drive signal is applied to the S2 terminal. Therefore, the failure diagnosis circuit 240 fails the vibration element 100 based on the vibration level of the signal input from the S1 terminal or the S2 terminal at the time t1 when the predetermined time T elapses from the time t0 when the application of the drive signal is stopped. Can be diagnosed.

FIG. 13 is a flowchart showing an example of the procedure of the failure diagnosis method of the physical quantity detection device 1 of the present embodiment.

First, the physical quantity detection circuit 200 waits until the failure diagnosis mode is entered in step S1, and when the failure diagnosis mode is entered, the drive signal is applied to the first detection electrode 40 in step S2.

Next, in step S3, the physical quantity detection circuit 200 stops applying the drive signal to the first detection electrode 40.

Next, in step S4, the process waits until a predetermined time elapses. After a lapse of a predetermined time, in step S5, the physical quantity detection circuit 200 performs a failure diagnosis of the vibrating element 100 based on the output signal from the first detection electrode 40.

Next, in step S6, when the vibrating element 100 fails due to the diagnosis in step S5, in step S7, the physical quantity detection circuit 200 writes 1 in the first detection failure flag to raise the failure diagnosis signal to a high level. In step S6, if the vibrating element 100 is normal according to the diagnosis of step S5, step S7 is not performed.

Next, in step S8, the physical quantity detection circuit 200 applies a drive signal to the second detection electrode 42.

Next, in step S9, the physical quantity detection circuit 200 stops applying the drive signal to the second detection electrode 42.

Next, in step S10, the process waits until a predetermined time elapses. After a lapse of a predetermined time, in step S11, the physical quantity detection circuit 200 performs a failure diagnosis of the vibrating element 100 based on the output signal from the second detection electrode 42.

Next, in step S12, when the vibrating element 100 fails due to the diagnosis in step S11, the physical quantity detection circuit 200 writes 1 in the second detection failure flag in step S13 to raise the failure diagnosis signal to a high level. In step S12, if the vibrating element 100 is normal according to the diagnosis of step S11, step S13 is not performed.

Then, in the step S14, the physical quantity detection circuit 200 waits until the mode shifts to the normal operation mode, and when the mode shifts to the normal operation mode, the physical quantity detection circuit 200 returns to the step S1.

In this embodiment, the normal operation mode is an example of the "first mode", and the failure diagnosis mode is an example of the "second mode". Further, the first detection electrode 40 or the second detection electrode 42 is an example of the "first electrode", and the first detection vibration arm 130 or the second detection vibration arm 132 is an example of the "first vibration arm". Further, the drive input electrode 30 is an example of the "second electrode", and the third drive vibrating arm 124 and the fourth drive vibrating arm 126 are examples of the "second vibrating arm". The CTL terminal is an example of an "input terminal".

As described above, in the physical quantity detection device 1 and the failure diagnosis method thereof of the present embodiment, the drive circuit 210 is provided on the third drive vibration arm 124 and the fourth drive vibration arm 126 of the vibration element 100 in the normal operation mode. A drive signal is applied to the drive input electrode 30, and the detection circuit 220 provides an output signal from the first detection electrode 40 provided on the first detection vibration arm 130 and a second detection provided on the second detection vibration arm 132. A physical quantity detection signal is generated based on the output signal from the electrode 42.

Further, in the failure diagnosis mode, the drive circuit 210 applies a drive signal to the first detection electrode 40, so that if the first detection electrode 40 is normal, the first detection vibration arm 130 vibrates with a predetermined amplitude, and then. When the application of the drive signal to the first detection electrode 40 is stopped, the vibration of the first detection vibration arm 130 gradually decreases. As a result, the amplitude of the output signal from the first detection electrode 40 gradually decreases, but the output signal from the first detection electrode 40 a predetermined time after the application of the drive signal to the first detection electrode 40 is stopped. The amplitude level of is within a certain range. Similarly, when the drive circuit 210 applies a drive signal to the second detection electrode 42, the second detection vibrating arm 132 vibrates with a predetermined amplitude if the second detection electrode 42 is normal, and then the second detection. When the application of the drive signal to the electrode 42 is stopped, the vibration of the second detection vibration arm 132 gradually decreases. As a result, the amplitude of the output signal from the second detection electrode 42 gradually decreases, but the output signal from the second detection electrode 42 a predetermined time after the application of the drive signal to the second detection electrode 42 is stopped. The amplitude level of is within a certain range.

On the other hand, even if the drive circuit 210 applies a drive signal to the first detection electrode 40, if the first detection electrode 40 has a failure such as opening or short circuit, the first detection vibration arm 130 hardly vibrates or or If the first detection electrode 40 is peeled off, the first detection vibration arm 130 vibrates with an amplitude smaller than a predetermined amplitude. As a result, the amplitude level of the output signal from the first detection electrode 40 after a predetermined time after stopping the application of the drive signal to the first detection electrode 40 is not included in a certain range. Therefore, in the failure diagnosis circuit 240, the failure of the vibrating element 100 is based on the output signal from the first detection electrode 40 after a predetermined time after the drive circuit 210 stops applying the drive signal to the first detection electrode 40. You can make a diagnosis. Similarly, even if the drive circuit 210 applies a drive signal to the second detection electrode 42, if there is a failure such as an open or short circuit in the second detection electrode 42, the second detection vibration arm 132 hardly vibrates or or If the second detection electrode 42 is peeled off, the second detection vibration arm 132 vibrates with an amplitude smaller than a predetermined amplitude. As a result, the amplitude level of the output signal from the second detection electrode 42 after a predetermined time after the application of the drive signal to the second detection electrode 42 is stopped is not included in a certain range. Therefore, in the failure diagnosis circuit 240, the failure of the vibrating element 100 is based on the output signal from the second detection electrode 42 after a predetermined time after the drive circuit 210 stops applying the drive signal to the second detection electrode 42. You can make a diagnosis.

Specifically, when the first detection electrode 40 is normal, the magnitude of the output signal from the first detection electrode 40 after a predetermined time after stopping the application of the drive signal to the first detection electrode 40 is the first. Assuming that the range is 1, for example, when an open, short-circuit or peeling failure occurs in the first detection electrode 40, the magnitude of the output signal from the first detection electrode 40 is the lower limit value of the first range. Therefore, the failure diagnosis circuit 240 can diagnose that the vibrating element 100 is a failure. Similarly, when the second detection electrode 42 is normal, the magnitude of the output signal from the second detection electrode 42 after a predetermined time after stopping the application of the drive signal to the second detection electrode 42 is the first. Assuming that the range is, for example, when the second detection electrode 42 has an open, short-circuited or peeled failure, the magnitude of the output signal from the second detection electrode 42 is larger than the lower limit of the first range. Since it becomes smaller, the failure diagnosis circuit 240 can diagnose that the vibrating element 100 is a failure.

Since this failure diagnosis does not utilize the drive vibration leaking from the drive vibration arm 120, 122, 124, 126 of the vibration element 100 to the first detection electrode 40 and the second detection electrode 42, the first detection electrode 40 And the vibration element 100 tuned so that vibration leakage hardly occurs in the second detection electrode 42 can be used. As a result, in the normal operation mode, the noise component due to vibration leakage is reduced in the physical quantity detection signal generated by the detection circuit 220 based on the output signal from the first detection electrode 40 and the output signal from the second detection electrode 42. Therefore, the deterioration of the S / N ratio of the physical quantity detection signal is reduced. Therefore, according to the physical quantity detection device 1 of the present embodiment and the failure diagnosis method thereof, it is possible to reduce the influence of noise caused by vibration leakage and perform failure diagnosis of the vibration element 100.

Further, in the physical quantity detection device 1 and the failure diagnosis method thereof of the present embodiment, in the normal operation mode, the failure diagnosis circuit 240 performs a failure diagnosis of the drive circuit 210 based on the drive signal. Therefore, according to the physical quantity detection device 1 of the present embodiment and the failure diagnosis method thereof, not only the failure of the vibrating element 100 but also the failure of the drive circuit 210 can be diagnosed.

Further, according to the physical quantity detection device 1 of the present embodiment and the failure diagnosis method thereof, a failure diagnosis is performed when a static signal indicating that the physical quantity detection device 1 is stationary is input to the CTL terminal in the normal operation mode. Since the mode shifts to the mode, the failure diagnosis circuit 240 can perform failure diagnosis of the vibration element 100 by eliminating the influence of the angular velocity applied to the vibration element 100 in the failure diagnosis mode.

2. 2. Modification Example In each of the above embodiments, as the physical quantity detecting device 1, an angular velocity detecting device including a vibrating element 100 for detecting an angular velocity is given as an example, but the physical quantity detected by the vibrating element 100 is not limited to the angular velocity and is an angular acceleration. , Acceleration, velocity, force, etc.

Further, the vibrating piece of the vibrating element 100 does not have to be a double T type, for example, the planar shape may be H type, a tuning fork type or a comb tooth type, a triangular prism, a square prism, and the like. It may be a tuning fork type having a cylindrical shape or the like.

As the material of the vibrating piece of the vibrating element 100, instead of the crystal (SiO ₂ ), for example, a piezoelectric single crystal such as lithium tantalate (LiTaO ₃ ) or lithium niobate (LiNbO ₃ ) or lead zirconate titanate is used. Piezoelectric materials such as piezoelectric ceramics such as (PZT) may be used.

Further, in each of the above embodiments, as the physical quantity detection device 1, a one-axis sensor including one vibration element 100 is given as an example, but the physical quantity detection device 1 is a multi-axis sensor including a plurality of vibration elements 100. May be. For example, the physical quantity detection device 1 may be a 3-axis gyro sensor including three vibrating elements that detect angular velocities around three different axes, a vibrating element that detects the angular velocity, and a vibrating element that detects acceleration. It may be a composite sensor provided with and.

The above-described embodiments and modifications are merely examples, and the present invention is not limited thereto. For example, it is also possible to appropriately combine each embodiment and each modification.

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

The following contents are derived from the above-described embodiments and modifications.

One aspect of the physical quantity detection device is
A vibrating element having a piezoelectric body including a first vibrating arm and a second vibrating arm, a first electrode provided on the first vibrating arm, and a second electrode provided on the second vibrating arm.
A drive circuit that applies a drive signal to the vibrating element,
A detection circuit that generates a physical quantity detection signal according to the physical quantity detected by the vibrating element based on the output signal from the first electrode.
A failure diagnosis circuit that diagnoses the failure of the vibrating element and
In the first mode, the first electrode is electrically connected to the detection circuit, the second electrode is electrically connected to the drive circuit, and in the second mode, the first electrode is connected to the drive circuit or the drive circuit or the drive circuit. Equipped with a failure diagnosis circuit and a switching circuit that electrically connects,
In the second mode, the drive circuit applies the drive signal to the first electrode and then stops applying the drive signal to the first electrode.
In the second mode, the failure diagnosis circuit vibrates based on the output signal from the first electrode after a predetermined time after the drive circuit stops applying the drive signal to the first electrode. Perform element failure diagnosis.

In this physical quantity detection device, in the second mode, the drive circuit applies a drive signal to the first electrode, so that the first vibrating arm vibrates with a predetermined amplitude if the first electrode is normal, and then the first. When the application of the drive signal to the electrodes is stopped, the vibration of the first vibrating arm gradually decreases. As a result, the amplitude of the output signal from the first electrode gradually decreases, but the amplitude level of the output signal from the first electrode is constant after a predetermined time after the application of the drive signal to the first electrode is stopped. Included in the range. On the other hand, even if the drive circuit applies a drive signal to the first electrode, if there is a failure such as an open or short circuit in the first electrode, the first vibrating arm hardly vibrates, or the first electrode is peeled off. Then, the first vibrating arm vibrates with an amplitude smaller than a predetermined amplitude. As a result, the amplitude level of the output signal from the first electrode after a predetermined time after stopping the application of the drive signal to the first electrode is not included in a certain range. Therefore, the failure diagnosis circuit can perform failure diagnosis of the vibrating element based on the output signal from the first electrode after a predetermined time after the drive circuit stops applying the drive signal to the first electrode. Since this failure diagnosis does not utilize the drive vibration leaking to the first electrode, a vibration element tuned so that vibration leakage hardly occurs in the first electrode can be used. As a result, in the physical quantity detection signal generated by the detection circuit based on the output signal from the first electrode in the first mode, the noise component due to vibration leakage is reduced, so that the S / N ratio of the physical quantity detection signal Deterioration is reduced. Therefore, according to this physical quantity detection device, it is possible to reduce the influence of noise caused by vibration leakage and perform failure diagnosis of the vibration element.

In one aspect of the physical quantity detecting device,
The first electrode is a first detection electrode and is
The second electrode is a drive input electrode and
In the first mode, the drive circuit applies the drive signal to the drive input electrode, and in the second mode, the drive circuit drives the first detection electrode without applying the drive signal to the drive input electrode. A signal may be applied.

According to this physical quantity detection device, in the first mode, the drive circuit applies a drive signal to the drive input electrode of the drive element, and the detection circuit generates a physical quantity detection signal based on the output signal from the first detection electrode. Can be done. Further, according to this physical quantity detection device, in the second mode, after the drive circuit applies the drive signal to the first detection electrode, the application of the drive signal to the first detection electrode is stopped, and the failure diagnosis circuit becomes the first. 1. Failure diagnosis of the vibrating element can be performed based on the output signal from the first detection electrode after a predetermined time after the application of the drive signal to the detection electrode is stopped.

In one aspect of the physical quantity detecting device,
When the three axes orthogonal to each other are the first axis, the second axis, and the third axis,
The thickness direction of the vibrating element is along the third axis,
The vibrating element is
At the base,
A first detection vibrating arm extending from the base along the second axis,
A first connecting arm and a second connecting arm extending from the base in opposite directions along the first axis,
The first drive vibrating arm and the second drive vibrating arm extending in opposite directions along the second axis from the tip of the first connecting arm,
It has a third drive vibrating arm and a fourth drive vibrating arm extending in opposite directions along the second axis from the tip of the second connecting arm.
The first vibrating arm is the first detected vibrating arm.
The second vibrating arm may be the third drive vibrating arm and the fourth drive vibrating arm.

According to this physical quantity detection device, in the first mode, the drive circuit applies a drive signal to the second electrode provided on the third drive vibration arm and the fourth drive vibration arm, and the detection circuit is applied to the first detection vibration arm. A physical quantity detection signal can be generated based on the output signal from the provided first electrode. Further, according to this physical quantity detection device, in the second mode, after the drive circuit applies the drive signal to the first electrode provided on the first detection vibrating arm, the application of the drive signal to the first electrode is stopped. The failure diagnosis circuit can perform failure diagnosis of the vibrating element based on the output signal from the first electrode after a predetermined time has passed since the application of the drive signal to the first electrode is stopped.

In one aspect of the physical quantity detecting device,
In the failure diagnosis circuit, the magnitude of the output signal from the first electrode after a predetermined time after the drive circuit stops applying the drive signal to the first electrode is not included in the first range. In some cases, it may be diagnosed as a failure.

According to this physical quantity detection device, when the first electrode is normal, the magnitude of the output signal from the first electrode after a predetermined time after stopping the application of the drive signal to the first electrode is in the first range. If, for example, when an open, short-circuit, or peeling failure occurs in the first electrode, the magnitude of the output signal from the first electrode becomes smaller than the lower limit of the first range, so that the failure occurs. The diagnostic circuit can diagnose that the vibrating element is out of order.

In one aspect of the physical quantity detecting device,
The failure diagnosis circuit may perform failure diagnosis of the drive circuit based on the drive signal.

According to this physical quantity detection device, it is possible to diagnose not only the failure of the vibrating element but also the failure of the drive circuit.

One aspect of the physical quantity detecting device is
Equipped with an input terminal
In the first mode, when a stationary signal indicating that the physical quantity detection device is stationary is input to the input terminal, the mode may be shifted to the second mode.

According to this physical quantity detection device, in the second mode, it is possible to eliminate the influence of the physical quantity applied to the vibrating element and perform failure diagnosis of the vibrating element.

One aspect of the failure diagnosis method of the physical quantity detection device is
A vibrating element having a piezoelectric body including a first vibrating arm and a second vibrating arm, a first electrode provided on the first vibrating arm, and a second electrode provided on the second vibrating arm.
A drive circuit that applies a drive signal to the vibrating element,
A detection circuit that generates a physical quantity detection signal according to the physical quantity detected by the vibrating element based on the output signal from the first electrode.
It is a failure diagnosis method of a physical quantity detection device equipped with
The step of applying the drive signal to the first electrode and
The step of stopping the application of the drive signal to the first electrode, and
A step of performing a failure diagnosis of the vibrating element based on an output signal from the first electrode after a predetermined time after stopping the application of the drive signal to the first electrode is included.

In the failure diagnosis method of this physical quantity detection device, by applying a drive signal to the first electrode, if the first electrode is normal, the first vibrating arm vibrates with a predetermined amplitude, and then the first electrode is driven. When the application of the signal is stopped, the vibration of the first vibrating arm gradually decreases. As a result, the amplitude of the output signal from the first electrode gradually decreases, but the amplitude level of the output signal from the first electrode is constant after a predetermined time after the application of the drive signal to the first electrode is stopped. Included in the range. On the other hand, even if a drive signal is applied to the first electrode, if there is a failure such as an open or short circuit in the first electrode, the first vibrating arm hardly vibrates, or if the first electrode is peeled off, The first vibrating arm vibrates with an amplitude smaller than a predetermined amplitude. As a result, the amplitude level of the output signal from the first electrode after a predetermined time after the application of the drive signal to the first electrode is stopped is not included in a certain range. Therefore, it is possible to diagnose the failure of the vibrating element based on the output signal from the first electrode after a predetermined time after stopping the application of the drive signal to the first electrode. Since this failure diagnosis does not utilize the drive vibration leaking to the first electrode, a vibration element tuned so that vibration leakage hardly occurs in the first electrode can be used. As a result, in the physical quantity detection signal generated by the detection circuit based on the output signal from the first electrode, the noise component due to vibration leakage is reduced, so that the deterioration of the S / N ratio of the physical quantity detection signal is reduced. .. Therefore, according to the failure diagnosis method of this physical quantity detection device, it is possible to reduce the influence of noise caused by vibration leakage and perform failure diagnosis of the vibrating element.

1 ... Physical quantity detector, 2a ... 1st main surface, 2b ... 2nd main surface, 3 ... side surface, 5 ... wide part, 10 ... base, 30 ... drive input electrode, 32 ... drive output electrode, 40 ... first detection Electrodes, 42 ... 2nd detection electrode, 44 ... 3rd detection electrode, 46 ... 4th detection electrode, 50 ... drive input wiring, 50a ... terminal part, 52 ... drive output wiring, 52a ... terminal part, 60 ... 1st detection Wiring, 60a ... Terminal part, 62 ... Second detection wiring, 62a ... Terminal part, 64 ... Third detection wiring, 64a ... Terminal part, 66 ... Fourth detection wiring, 66a ... Terminal part, 100 ... Vibration element, 101 ... Dielectric body, 110 ... 1st connecting arm, 112 ... 2nd connecting arm, 120 ... 1st driving vibrating arm, 122 ... 2nd driving vibrating arm, 124 ... 3rd driving vibrating arm, 126 ... 4th driving vibrating arm, 130 ... 1st detected vibrating arm, 132 ... 2nd detected vibrating arm, 140 ... 1st support, 142 ... 2nd support, 150 ... 1st beam, 152 ... 2nd beam, 154 ... 3rd beam, 156 ... 4th beam, 200 ... physical quantity detection circuit, 210 ... drive circuit, 211 ... I / V conversion circuit, 212 ... AGC circuit, 213 ... comparator, 214 ... start circuit, 220 ... detection circuit, 221P, 221N ... Q / V conversion circuit, 222 ... differential amplifier, 223 ... high pass filter, 224 ... AC amplifier, 225 ... synchronous detection circuit, 226 ... sensitivity adjustment amplifier, 227 ... switched capacitor filter, 228 ... ratiometric amplifier, 230A, 230B ... Voltage judgment circuit, 240 ... Failure diagnosis circuit, 250 ... Control circuit, 260 ... Storage unit, 270 ... Interface circuit, 280 ... Switching circuit, 281-287 ... Switch

Claims (7)

A vibrating element having a piezoelectric body including a first vibrating arm and a second vibrating arm, a first electrode provided on the first vibrating arm, and a second electrode provided on the second vibrating arm.
A drive circuit that applies a drive signal to the vibrating element,
A detection circuit that generates a physical quantity detection signal according to the physical quantity detected by the vibrating element based on the output signal from the first electrode.
A failure diagnosis circuit that diagnoses the failure of the vibrating element and
In the first mode, the first electrode is electrically connected to the detection circuit, the second electrode is electrically connected to the drive circuit, and in the second mode, the first electrode is connected to the drive circuit or the drive circuit or the drive circuit. Equipped with a failure diagnosis circuit and a switching circuit that electrically connects,
In the second mode, the drive circuit applies the drive signal to the first electrode and then stops applying the drive signal to the first electrode.
In the second mode, the failure diagnosis circuit vibrates based on the output signal from the first electrode after a predetermined time after the drive circuit stops applying the drive signal to the first electrode. A physical quantity detection device that diagnoses device failures. In claim 1,
The first electrode is a first detection electrode and is
The second electrode is a drive input electrode and
In the first mode, the drive circuit applies the drive signal to the drive input electrode, and in the second mode, the drive circuit drives the first detection electrode without applying the drive signal to the drive input electrode. A physical quantity detector that applies a signal. In claim 1 or 2,
When the three axes orthogonal to each other are the first axis, the second axis, and the third axis,
The thickness direction of the vibrating element is along the third axis,
The vibrating element is
At the base,
A first detection vibrating arm extending from the base along the second axis,
A first connecting arm and a second connecting arm extending from the base in opposite directions along the first axis,
The first drive vibrating arm and the second drive vibrating arm extending in opposite directions along the second axis from the tip of the first connecting arm,
It has a third drive vibrating arm and a fourth drive vibrating arm extending in opposite directions along the second axis from the tip of the second connecting arm.
The first vibrating arm is the first detected vibrating arm.
The second vibrating arm is a physical quantity detection device, which is the third drive vibrating arm and the fourth drive vibrating arm. In any one of claims 1 to 3,
In the failure diagnosis circuit, the magnitude of the output signal from the first electrode after a predetermined time after the drive circuit stops applying the drive signal to the first electrode is not included in the first range. A physical quantity detector that diagnoses a failure in case of failure. In any one of claims 1 to 4,
The failure diagnosis circuit is a physical quantity detection device that diagnoses a failure of the drive circuit based on the drive signal. In any one of claims 1 to 5,
Equipped with an input terminal
A physical quantity detection device that shifts to the second mode when a static signal indicating that the physical quantity detection device is stationary is input to the input terminal in the first mode. A vibrating element having a piezoelectric body including a first vibrating arm and a second vibrating arm, a first electrode provided on the first vibrating arm, and a second electrode provided on the second vibrating arm.
A drive circuit that applies a drive signal to the vibrating element,
A detection circuit that generates a physical quantity detection signal according to the physical quantity detected by the vibrating element based on the output signal from the first electrode.
It is a failure diagnosis method of a physical quantity detection device equipped with
The step of applying the drive signal to the first electrode and
The step of stopping the application of the drive signal to the first electrode, and
A physical quantity detecting device including a step of performing a failure diagnosis of the vibrating element based on an output signal from the first electrode after a predetermined time after stopping the application of the drive signal to the first electrode. Failure diagnosis method.

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