JP2012242101A - Angular velocity sensor with self-diagnosis function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular velocity sensor which simplifies and downsizes a tuning fork type vibrator through self-diagnosis by commonly using an oscillation circuit.SOLUTION: In an angular velocity sensor with a self-diagnosis function, a drive electrode (9), a detection electrode (20) and self-diagnosing electrodes (6 and 7) are provided on a tuning fork type vibrator (1), and each arm part (2 and 3) of the tuning fork type vibrator (1) is driven symmetrically or asymmetrically by selectively turning on/off each self-diagnosing electrode (6 and 7) and the drive electrode (9) through a pair of switches (SW1 and SW2) and commonly using only one oscillation circuit (10).

Description

  The present invention relates to an angular velocity sensor having a self-diagnosis function, and more particularly to a novel improvement for simplifying and miniaturizing a tuning fork type vibrator by performing self-diagnosis using an oscillation circuit in common.

In general, an angular velocity sensor is a sensor that detects an angular velocity at the time of rotation, and has recently been frequently used in a system such as a car navigation system, an attitude control system of an automobile or a robot, and the like.
For example, Patent Document 1 discloses an angular velocity sensor using a tuning fork vibrator, and generates a signal having a different phase and amplitude on the circuit side at the time of self-diagnosis, and inputs the signal to the vibration electrode. An angular velocity sensor having a function of determining a self-diagnosis of a detection unit by artificially generating a detection vibration is disclosed.
On the other hand, in Patent Document 2, the pseudo angular velocity signal generated by the pseudo signal generation circuit is superimposed on the drive signal, and the angular velocity pseudo signal propagating through the electrostatic coupling capacitance of the drive electrode and the detection electrode is detected. An angular velocity sensor having a diagnosis determination function is disclosed.
Furthermore, in Patent Document 3, the configuration of the oscillation circuit is switched via a switch between normal time and self-diagnosis, and a tuning fork vibration mode at the time of diagnosis is different from the detection mode.

JP 2010-107518 A JP 2010-43962 A Japanese Patent No. 4529444

Since the conventional self-diagnosis device and method for angular velocity sensors are configured as described above, the following problems exist.
That is, in the configuration of Patent Literature 1, it is necessary to add a self-diagnosis gain adjustment / phase adjustment circuit to the oscillation circuit of the sensor element, and at least four amplifiers are additionally required. On the other hand, the configuration of Patent Document 2 requires a pseudo signal generation circuit and a nonvolatile storage unit that stores a set value. There was a problem of increasing the circuit scale.
Further, in the configuration of Patent Document 3, since diagnosis is performed by driving in the Z-axis common mode, diagnosis is always possible, but there are many parts that require adjustment on the circuit, and the circuit configuration is also complicated. .

  The present invention has been made to solve the above-described problems. In particular, the self-diagnosis electrode is connected to the drive electrode via a switch, and only one oscillation circuit is used for angular velocity detection and self-diagnosis. It is an object of the present invention to provide a small angular velocity sensor having a simplified self-diagnosis function with a simplified circuit configuration.

  An angular velocity sensor having a self-diagnosis function according to the present invention includes a tuning fork vibrator having a base portion and a pair of arm portions extending in a forked manner from the base portion, a pair of drive electrodes provided on the arm portion, An angular velocity sensor element having a pair of detection electrodes provided on the arm part, and first and second self-diagnosis electrodes provided on the surface of the base part, and only one connected to the drive electrode And an oscillation circuit and switch means for connecting or disconnecting the drive electrode and the oscillation circuit to and from each of the self-diagnosis electrodes. When the switch means is off, the arms are driven symmetrically. When the switch means is on, the arm portions are driven asymmetrically, and the switch means comprises a pair of switches connected to the self-diagnosis electrodes. The switch can be short-circuited only on one side, and when one switch is turned ON / OFF, the output is determined when the circuit is open and short-circuited. The output is stationary when open, the sensitivity changes, the gain changes, and the circuit malfunctions when short-circuited. In addition, one self-diagnosis electrode is provided on each of the left and right sides of the base portion, and the oscillation circuit and one of the electrodes are alternately connected via each switch. The phase of the detected vibration of the tuning fork vibrator can be switched between open and short of the left and right self-diagnostic electrodes by turning each switch on and off. And can perform self-diagnosis to determine sensitivity change corresponding to right rotation and left rotation, output change at rest, and circuit operation abnormality. One of the switches is turned ON, and at that time, a second offset adjustment region is provided in the vicinity of 1/2 Vdd of the offset voltage of the angular velocity sensor, and the determination threshold for output at rest, sensitivity change, and circuit operation abnormality may be made common. In addition, by changing the electrode size of the self-diagnostic electrode according to the size of the diagnostic signal, the amplitude of the self-diagnostic signal can be changed only by changing the electrode size without affecting the sensitivity obtained by the angular velocity. The size can be adjusted, and by adjusting the output change difference generated in each of the self-diagnostic electrodes, the magnitude of the detected vibration signal with the output difference can be monitored to This is a configuration capable of diagnosing a change in output and a change in sensitivity.

Since the angular velocity sensor having a self-diagnosis function according to the present invention is configured as described above, the following effects can be obtained.
That is, a tuning fork vibrator having a base portion and a pair of arm portions extending in a forked manner from the base portion, a pair of drive electrodes provided on the arm portion, and a pair of detections provided on the arm portion An angular velocity sensor element having an electrode and first and second self-diagnosis electrodes provided on the surface of the base portion, only one oscillation circuit connected to the drive electrode, and each of the self-diagnosis electrodes Switch means for connecting or disconnecting the drive electrode and the oscillation circuit, and when the switch means is off, the arm portions are driven symmetrically, and when the switch means is on Each of the arms is driven asymmetrically.
In addition, each switch of the switch means can be short-circuited only on one side, and by ON / OFF of one switch, the output judgment at the time of opening and short-circuiting, the output at rest when opening, sensitivity change, gain change at short-circuiting Self-diagnosis for determining circuit operation abnormality can be performed.
Each of the self-diagnosis electrodes is provided on the left and right sides of the base portion, and can be electrically short-circuited or opened with the oscillation circuit and one of the drive electrodes via each switch.
In addition, the phase of the detected vibration of the tuning fork vibrator can be changed by switching between open and short of the left and right self-diagnostic electrodes by turning each switch on and off, and sensitivity changes corresponding to right rotation and left rotation In addition, self-diagnosis can be performed to determine output change at rest and circuit operation abnormality.
In addition, when one of the switches is turned ON, a second offset adjustment area is provided in the vicinity of 1/2 Vdd of the offset voltage of the angular velocity sensor, and the judgment threshold for output at rest, sensitivity change, and circuit operation abnormality is shared. can do.
Further, by changing the electrode size of the self-diagnosis electrode according to the size of the diagnostic signal, the amplitude of the self-diagnosis signal is adjusted only by changing the electrode size without affecting the sensitivity obtained by the angular velocity. be able to.
In addition, by adjusting the output change difference generated in each of the electrodes for self-diagnosis, monitoring the magnitude of the detected vibration signal having the output difference makes it possible to diagnose a change in output and a change in sensitivity at rest. .
Therefore, according to the present invention, a self-diagnosis electrode is arranged on the base of the tuning fork vibrator, and this self-diagnosis electrode is selectively connected to the drive electrode and the oscillation circuit by opening and closing the SW. It is possible to obtain an angular velocity sensor having self-diagnosis such as hourly output change, sensitivity change, and circuit operation abnormality.

It is a block diagram which shows the tuning fork type | mold vibrator of the angular velocity sensor which has a self-diagnosis function by this invention. FIG. 2 is a perspective view showing a state where electrodes are formed on the vibrator of FIG. 1. It is sectional drawing which shows the cross section G of FIG. It is sectional drawing which shows the cross section H of FIG. It is sectional drawing which shows the cross section I of FIG. It is a block diagram which shows the angular velocity sensor by this invention. FIG. 3 is an explanatory diagram showing drive impedance of the vibrator of FIG. 2. FIG. 3 is an explanatory diagram showing drive impedance of the vibrator of FIG. 2. It is a block diagram which shows the modification of FIG. It is a characteristic view which shows the sensitivity of the angular velocity sensor of this invention. It is a characteristic view which shows the self-diagnosis state in this invention. It is a characteristic view which shows the self-diagnosis state in this invention. It is a characteristic view which shows the self-diagnosis state in this invention. It is a deformation | transformation characteristic view of FIG.

  An object of the present invention is to provide an angular velocity sensor having a self-diagnosis function that is miniaturized by performing self-diagnosis using a tuning fork type vibrator as an oscillation circuit in common.

A preferred embodiment of an angular velocity sensor having a self-diagnosis function according to the present invention will be described below with reference to the drawings.
First, the driving vibration and the detection vibration of the tuning fork vibrator 1 will be described with reference to FIGS.
Referring to FIG. 1 (a), when a drive signal is applied to a drive electrode (not shown) of the tuning fork vibrator 1, vibrations occur such that the left and right arm portions 2 and 3 open and close each other. This vibration is a vibration parallel to the X axis. Such vibration is called drive vibration. Here, when an angular velocity is applied to the Y-axis, the left and right arm portions 2 and 3 vibrate back and forth as shown in FIG. This vibration is a vibration parallel to the Z axis. Such vibration is called detection vibration. When the detection electrodes 20 and 20a detect this detection vibration, the angular velocity about the Y axis can be detected. The longitudinal direction of the arms 2 and 3 of the tuning fork vibrator 1 is defined as the Y axis, the width direction as the X axis, and the thickness direction as the Z axis (the same applies hereinafter).

Example 1
The first embodiment is an example in which self-diagnosis electrodes 6 and 7 are provided on the tuning fork vibrator 1 used for the angular velocity sensor 5.
2 is a perspective view in which the self-diagnosis electrodes 6 and 7 are arranged on the base portion 8 of the tuning fork vibrator 1, and FIGS. 3 to 5 show the front surface A, side surfaces C and D, and the back surface of the arm portions 2 and 3, respectively. 6 shows a pair of detection electrodes 20 and 20a formed to be separated from each other, and FIG. 6 shows the self-diagnosis electrodes 6 and 7 arranged in the tuning fork type vibrator 1 as switches SW1 and SW1 of the switch means 40. FIG. 4 is a circuit block diagram showing that a drive electrode 9 and only one oscillation circuit 10 are opened and short-circuited by opening and closing SW2. The SW 2 is switched to the normal mode in which the arm portions 2 and 3 are opened symmetrically when viewed from the plane by SW-OFF, and the self-diagnosis mode is switched by SW-ON. When a short-circuit state occurs at the time of SW-ON, the pair of drive electrodes 9 become unbalanced, and the arm portions 2 and 3 are asymmetrically driven (shown in FIG. 8), and pseudo detection vibration is generated. The well-known FEM analysis results are shown in FIGS. FIG. 7 shows the analysis result of the impedance response of the SW-OFF drive electrode 9, and only the drive vibration that vibrates in the X direction is obtained. On the other hand, FIG. 8 shows the analysis result of the impedance response of the drive electrode 9 at the time of SW-ON. In addition to the drive vibration that vibrates in the X direction, a detection vibration that vibrates in the Z direction is generated. 6 and 7 can generate a detection vibration in a pseudo manner. In other words, in FIG. 8, each arm part 2, 3 is driven asymmetrically when viewed in a plane, thereby causing vertical movement.

FIGS. 9 and 10 show examples of actual measurement of output changes by the self-diagnosis electrodes 6 and 7. The horizontal axis shows the sensitivity in the normal mode (SW-OFF) in which the arms 2 and 3 are driven symmetrically, and the vertical axis shows the output change in the self-diagnosis mode (SW-ON) with the sensitivity in the normal mode. It is a converted value. SW1 and SW2 are alternately turned on and off. SW1-ON (SW2-OFF) indicates a positive output change, and SW2-ON (SW1-OFF) indicates a negative output change. By switching between SW1 and SW2, an output change (pseudo sensitivity) corresponding to right rotation and left rotation occurs. Further, the sensitivity in the normal mode and the output change (pseudo sensitivity) at SW-ON are highly correlated. As described above, the self-diagnosis electrodes 6 and 7 are arranged on the tuning fork vibrator 1, and the self-diagnosis electrodes 6 and 7 and the drive electrode 9 and the oscillation circuit 10 are short-circuited or opened by opening and closing the switches SW1 and SW2. Thus, it is possible to detect a change in sensitivity by generating pseudo detection vibration and monitoring the pseudo sensitivity.
Although the normal mode is set to SW-OFF, even if the normal mode is set to the SW1, 2-ON state and the SW-1, 2 are turned off in the self-diagnosis mode, each drive electrode 9 is unbalanced. Needless to say, since the arm portions 2 and 3 are driven asymmetrically, detection vibration is generated in a pseudo manner (not shown).

(Example 2)
The second embodiment shows a self-diagnosis method using a circuit of a combination of a tuning-fork vibrator and a SW on which self-diagnosis electrodes are arranged as described above.
FIG. 11 shows an example of self-diagnosis by alternately opening and closing the switches SW1 and SW2. In FIG. 11, Vout is an offset voltage of the angular velocity sensor, V1 and V2 are output values when SW1 and SW2 are ON, thresholds AU and AL are determination thresholds when SW1 is ON, and thresholds BU and BL are determinations when SW2 is ON. Indicates the threshold value. When the switch SW1 is turned on, the sensor output changes in the plus direction, and when the switch SW2 is turned on, the sensor output changes in the minus direction.
A fault is determined by setting an upper limit value and a lower limit value for (V1, V2), respectively, and confirming that the output during change is within the set value.
Table 1 shows the determination table. A combination of determinations when SW1 and SW2 are ON can detect a change in output at rest, a change in sensitivity, and an abnormal circuit operation.

(Example 3)
The third embodiment shows an example of a self-diagnosis method using a circuit of a combination of the tuning fork vibrator 1 and the SW on which the self-diagnosis electrodes 6 and 7 are arranged.
FIG. 12 shows an example of self-diagnosis by opening and closing only the switch SW1 (or SW2). In FIG. 12, Vout is an offset voltage of the angular velocity sensor 5, V1 is an output value when the switch SW1 is ON, ΔVout1 is an output difference between SW-OFF and SW-ON, and thresholds AU and AL are when SW1 is OFF (stationary). Threshold), threshold values BU and BL indicate determination threshold values when SW1-ON.
First, Vout (output when SW1 is OFF) is measured, and then output (V1) when switch SW1 is turned ON is measured.
As a first example, a determination is made as to whether or not the value of Vout falls within the set value. As a second example, whether or not V1−Vout = ΔVout1 falls within the set value is determined.
Table 2 shows the judgment table. A combination of output difference determination at SW1-OFF and SW1-ON can detect stationary output change, sensitivity change, gain change, and circuit operation abnormality.

Example 4
The fourth embodiment shows a self-diagnosis method using a circuit of a combination of the tuning fork vibrator 1 on which the self-diagnosis electrodes 6 and 7 are arranged and the switches SW1 and SW2.
FIG. 13 shows an example of self-diagnosis by turning on one of the switches SW1 and SW2, performing the second offset adjustment, and checking the output value at SW-OFF and the output value at SW-ON. Show. In FIG. 13, Vout is an offset voltage of the angular velocity sensor, V1 is an output value when SW1 is ON, and ΔVout1 is an output difference between SW-OFF and SW-ON.
First, Vout (output in the state of SW1-OFF) is measured, then SW1 or SW2 is turned on, and then the output (Vout) when the second offset adjustment is performed is measured.
Self-diagnosis is performed by checking whether the values of Vout (SW-OFF) and Vout (SW-ON) are within a certain range (common to threshold values). In this embodiment, the threshold value can be shared.
The second offset adjustment is a function for adjusting the offset voltage, Vout, of the angular velocity sensor 5 to be around 1/2 Vdd when the switch SW1 or SW2 is turned on.

(Example 5)
In the fifth embodiment, the tuning fork vibrator 1 used for the angular velocity sensor 5 is provided with self-diagnosis electrodes 6 and 7 having different output changes.
FIG. 14 shows an example of an output change when an output difference is given by the self-diagnosis electrodes 6 and 7 (example of SW1). The horizontal axis represents the sensitivity in the normal mode (SW-OFF), and the vertical axis represents the value converted into the angular velocity by the sensitivity in the normal mode of the output change in the self-diagnosis mode (SW-ON).
By monitoring the magnitude of the detected vibration signal having a difference in output, it is possible to diagnose a change in output and sensitivity at rest in different ranges. The output difference can be arbitrarily changed depending on the size of the self-diagnosis electrode, and this embodiment is an example in which the size (area) of the self-diagnosis electrode 6 is 50% smaller than the self-diagnosis electrode 7. Note that the output difference may be given not only by the electrode dimensions but also by other methods such as electrode arrangement (based on FIG. 6).
The oscillation circuit 10 and the switches SW1 and SW2 of the angular velocity sensor 5 described above are configured by a well-known ASIC (Application Specific IC).

The configuration and function of the angular velocity sensor having the self-diagnosis function according to the present invention are summarized as follows.
That is, a tuning fork vibrator 1 having a base portion 8 and a pair of arm portions 2 and 3 extending in a bifurcated manner from the base portion 8, a pair of drive electrodes 9 provided on the arm portions 2 and 3, An angular velocity sensor element 30 having a pair of detection electrodes 20 and 20a provided on the arm portions 2 and 3 and first and second self-diagnosis electrodes 6 and 7 provided on the surface A of the base portion 8; And only one oscillation circuit 10 connected to the drive electrode 9 and switch means 40 for connecting (or not connecting) the drive electrode 9 and the oscillation circuit 10 to the self-diagnosis electrodes 6 and 7. And switch means 40 for connecting or disconnecting the drive electrode 9 and the oscillation circuit 10 to the second self-diagnosis electrode 7, and each arm portion 2 when the switch means 40 is off. , 3 are driven symmetrically in the plane It said switch means 40 when turned on the respective arm portions 2 and 3 are asymmetrically driven in a plan view.
The switch means 40 includes a pair of switches SW1 and SW2 connected to the self-diagnosis electrodes 6 and 7, respectively. The switches SW1 and SW2 can be short-circuited only on one side, and one switch ON / OFF With the output judgment at the time of opening and short-circuiting by OFF, it is possible to perform self-diagnosis for judging output at rest when opening, sensitivity change, gain change, and circuit operation abnormality when short-circuiting.
Each of the self-diagnosis electrodes 6 and 7 is provided on the left and right sides of the base portion 8 and is electrically short-circuited with the oscillation circuit 10 and one of the drive electrodes 9 via the switches SW1 and SW2. Or it can be open.
The phase of the detected vibration of the tuning fork vibrator 1 can be changed by switching the open / short circuit of the left and right self-diagnosis electrodes 6, 7 by turning on / off the switches SW1, SW2, Self-diagnosis can be performed to determine sensitivity change corresponding to counterclockwise rotation, output change at rest, and circuit operation abnormality.
In addition, one of the switches SW1 and SW2 is turned on, and at that time, a second offset adjustment region is provided in the vicinity of 1/2 Vdd of the offset voltage Vout of the angular velocity sensor 5, and output at rest, sensitivity change, and circuit operation abnormality are provided. A determination threshold can be shared.
Further, by changing the electrode dimensions of the self-diagnosis electrodes 6 and 7 according to the magnitude of the diagnostic signal, the magnitude of the amplitude of the self-diagnosis signal can be changed only by changing the electrode dimensions without affecting the sensitivity obtained by the angular velocity. Can be adjusted.
Further, by adjusting the output change difference generated in each of the self-diagnosis electrodes 6 and 7, the magnitude of the detected vibration signal having the output difference can be monitored, and the change in the output and the change in sensitivity can be diagnosed. it can.

  The angular velocity sensor having a self-diagnosis function according to the present invention is configured by a tuning fork type vibrator and only one oscillation circuit, thereby simplifying the configuration and reducing the size, and can be used for attitude control of a car navigation system, a robot, and the like.

DESCRIPTION OF SYMBOLS 1 Tuning fork type vibrator 2, 3 Arm part 5 Angular velocity sensor 6 1st self-diagnosis electrode 7 2nd self-diagnosis electrode 8 Base part 9 Drive electrode 10 Oscillation circuit 20, 20a Detection electrode 30 Angular velocity sensor element 40 Switch means A Surface B Back C Side C D Side SW1, SW2 Switch

Claims (7)

A tuning fork vibrator (1) having a base portion (8) and a pair of arm portions (2, 3) extending in a forked manner from the base portion (8) and the arm portion (2, 3) are provided. A pair of drive electrodes (9), a pair of detection electrodes (20, 20a) provided on the arm portions (2, 3), and a first surface provided on the surface (A) of the base portion (8). An angular velocity sensor element (30) having a second self-diagnosis electrode (6, 7);
Only one oscillation circuit (10) connected to the drive electrode (9) and the drive electrode (9) and the oscillation circuit (10) are connected to or disconnected from the self-diagnosis electrodes (6, 7). And switch means (40) for
When the switch means (40) is off, the arms (2, 3) are driven symmetrically, and when the switch means (40) is on, the arms (2, 3) are asymmetric. An angular velocity sensor having a self-diagnosis function, wherein   The switch means (40) comprises a pair of switches (SW1, SW2) connected to each of the self-diagnosis electrodes (6, 7), and the switches (SW1, SW2) can be short-circuited only on one side, It is characterized by the ability to perform self-diagnosis to judge the output at rest when open, the sensitivity change, gain change, and circuit operation abnormality when short-circuited by the output judgment at open and short circuit by ON / OFF of one switch An angular velocity sensor having a self-diagnosis function according to claim 1.   Each of the self-diagnosis electrodes (6, 7) is provided on the left and right sides of the base portion (8), and the oscillation circuit (10) and one of the electrodes are alternately connected via the switches (SW1, SW2). 2. The angular velocity sensor having a self-diagnosis function according to claim 1, wherein the angular velocity sensor can be short-circuited or opened with respect to the drive electrode.   The phase of the detected vibration of the tuning fork vibrator (1) can be changed by switching the open / short circuit of the left and right self-diagnosis electrodes (6, 7) by turning each switch (SW1, SW2) on and off. 2. An angular velocity sensor having a self-diagnosis function according to claim 1, wherein a self-diagnosis for judging a change in sensitivity corresponding to right rotation, left rotation, output change at rest, and circuit operation abnormality can be performed.   When one of the switches (SW1, SW2) is turned ON, a second offset adjustment area is provided in the vicinity of 1/2 Vdd of the offset voltage (Vout) of the angular velocity sensor (5), and the output at rest, sensitivity change, 2. The angular velocity sensor having a self-diagnosis function according to claim 1, wherein a judgment threshold value for circuit operation abnormality can be shared.   By changing the electrode dimensions of the self-diagnosis electrodes (6, 7) according to the magnitude of the diagnostic signal, the amplitude of the self-diagnostic signal can be changed only by changing the electrode dimensions without affecting the sensitivity obtained by the angular velocity. The angular velocity sensor having a self-diagnosis function according to claim 1, wherein the angular velocity sensor can be adjusted.   By adjusting the output change difference generated at each of the self-diagnostic electrodes (6, 7), the magnitude of the detected vibration signal having the output difference is monitored, thereby diagnosing the change in output and the change in sensitivity. The angular velocity sensor having a self-diagnosis function according to claim 1, wherein

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