JP2000146594A - Device for detecting breaking of wire in oscillatory sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device of detecting the breading of wires capable of reliably determining the breaking of a pair of signal lines. SOLUTION: As a signal line 4 is separated from a charge amplifier 7, which outputs a voltage corresponding to an inputted signal, a detection signal B is not transmitted through the signal line 4 in the case of the breaking of the signal line 4, and a drive signal A being added via a resistor 2 instead appears in the signal line 4. In addition, a signal line 5 is not broken, and a detection signal C appears in the signal line 5. A differential amplifier 9 outputs a signal D of sufficiently high level enough to indicate the difference between the signals of the signal lines 4 and 5. An AC amplifier 10 amplifies a signal D and outputs a signal E. A signal F from a synchronous detector 11 becomes a DC signal of sufficiently high level, and a signal G from an integrator 12 becomes a DC signal of sufficiently high level. A comparator 13 determines the breaking of the line 4 on the basis that the level of the signal G is higher than a positive threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disconnection detecting device for a vibration type sensor such as a yaw rate sensor.

[0002]

2. Description of the Related Art As an apparatus of this kind, there is, for example, one having a configuration as shown in FIG. In FIG. 8, a yaw rate sensor 101 detects an angular velocity acting on the yaw rate sensor 101. This yaw rate sensor 10
Numeral 1 oscillates upon application of the drive signal A and sends out a pair of detection signals B and C to the respective lines 104 and 105 via the charge amplifiers 102 and 103. Differential amplifier 1
Reference numeral 06 inputs the detection signals B and C, and outputs a signal D indicating the difference between the detection signals B and C. AC amplifier 1
07 amplifies the signal D and outputs the signal E. The synchronous detector 108 inverts the signal E every half cycle of the drive signal A,
A signal F is formed and output. The integrator 109 integrates the signal F to form and output a signal G.

FIG. 9 is a timing chart showing the waveform of each signal in the apparatus shown in FIG. In FIG. 9, the drive signal A is a square wave, and is applied to the yaw rate sensor 101 to cause the yaw rate sensor 101 to vibrate. From the yaw rate sensor 101 to the charge amplifiers 102 and 10
3, a pair of detection signals B and C are sent to the respective signal lines 104 and 105. These detection signals B and C include a component of the drive signal A caused by crosstalk. The components of the drive signal A included in these detection signals B and C are removed by the differential amplifier 106, and a signal D is obtained. The signal D includes a signal component of vibration leakage generated due to the structure of the yaw rate sensor 101. This signal D is amplified by the AC amplifier 107,
When the signal E is inverted every half cycle of the drive signal A by the synchronous detector 107 and the signal F is integrated by the integrator 108, the signal component of the vibration leakage included in the signal E is removed, and the yaw rate sensor 101 , Ie, a signal G indicating only the angular velocity acting on the yaw rate sensor 101 can be obtained.

Normally, the level of the signal G ranges from -100 mV to +
It is in the range of 100mV.

[0005] Conventionally, by comparing the output of the integrator 108 with a predetermined threshold value,
The disconnection of each of the signal lines 104 and 105 is detected.

FIG. 10 is a timing chart showing the waveform of each signal when the signal line 102 is disconnected. In FIG. 10, the level of the detection signal B on the signal line 104 is “0” because the signal line 104 is disconnected.
It has become. In this case, the level of the signal G is +500 mV
That is all. As described above, since the level of the signal G is usually -100 mV to +100 mV, the signal line 104
Is disconnected and the level of the signal G becomes equal to or more than +500 mV, the disconnection of the signal line 104 can be determined by comparing the level of the signal G with a predetermined threshold value.

FIG. 11 is a timing chart showing the waveform of each signal when the signal line 105 is disconnected. In FIG. 11, the detection signal B on the signal line 105 is a signal component fed back by the differential amplifier 106 because the signal line 105 is disconnected. in this case,
The level of the signal G becomes −several hundred mV to + several hundred mV. As described above, the level of the signal G is usually -100 mV to +100.
Since it is mV, even if the signal line 104 is disconnected and the level of the signal G becomes −several hundred mV to + several hundred mV, it can be determined that the signal line 104 is disconnected based on the level of the signal G. Is hard to say.

[0008]

As described above, when the signal line 104 is disconnected, the level of the signal G becomes +50.
0mV or more, the level of the normal signal G is -100mV ~
+100 mV, the signal line 10
4 can be determined, but when the signal line 105 is disconnected, the level of the signal G is −several hundred mV to + several hundred mV.
And the level of the normal signal G is −100 mV to +100
The signal line 10
5 cannot be reliably determined.

In addition, many yaw rate sensors mass-produced have a variation of about ± several hundred mV in the level of their output signals, and the level of the signal G varies accordingly, so that this point is taken into consideration. +5 of the signal G level
It cannot be said that the disconnection of each of the signal lines 104 and 105 is reliably determined based on a change of 00 mV or more or a change of ± several hundred mV.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problem, and has as its object to provide a disconnection detecting device for a vibration-type sensor capable of reliably determining disconnection of a pair of signal lines. And

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention provides a vibration-type sensor which vibrates upon receiving a drive signal and outputs a pair of signals, and a pair of vibration-type sensors. And a differential amplifier for differentially amplifying each of the detection signals from each of the charge amplifiers, based on an output of the differential amplifier. In the disconnection detecting device of the vibration type sensor for detecting disconnection of each signal line transmitting each of the detection signals, a synchronous signal for synchronizing with the drive signal is added to each of the signal lines transmitting each of the detection signals. Signal application means is provided.

According to the present invention, a synchronization signal synchronized with a drive signal is added to each signal line transmitting a pair of detection signals. If none of the signal lines is disconnected, each charge amplifier determines the voltage of each signal line according to the level of a pair of signals that are input to each charge amplifier. The influence of the synchronization signal does not appear on each signal line, and only each detection signal appears on each signal line. Further, when any one of the signal lines is disconnected, the disconnected signal line is disconnected from the charge amplifier, so that a synchronization signal appears on the disconnected signal line, and the synchronization signal also appears on the output of the differential amplifying means. Appears. For this reason, if the synchronization signal is detected at the subsequent stage of the differential amplifying means, it is possible to determine any disconnection of each signal line. Moreover, if the level of the synchronizing signal is set sufficiently higher than the level of each detection signal, it is possible to easily detect the component of the synchronizing signal from the output of the differential amplifying means, and to prevent disconnection of the signal line. The determination can be made reliably.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a disconnection detecting device for a vibration type sensor according to the present invention. In FIG. 1, an excitation circuit 1 receives a sine-wave excitation signal T and outputs a square-wave drive signal A synchronized with the excitation signal T. This drive signal A is applied to respective signal lines 4 and 5 via respective resistors 2 and 3. The yaw rate sensor 6 vibrates upon receiving the drive signal A, and outputs a pair of current signals to the charge amplifiers 7 and 8, respectively. These charge amplifiers 7 and 8 convert each current signal into a current and a voltage to form each detection signal B and C, and send each detection signal B and C to each signal line 4 and 5.

The detection signals B and C and the drive signal A are synchronized with each other. The detection signals B and C have the same phase as each other and have the opposite phase to the drive signal A.

In the signal line 4, the drive signal A is superimposed on the detection signal B, and in the signal line 5, the drive signal A is superimposed on the detection signal C.

Each of the charge amplifiers 7 and 8 is configured as shown in FIG. 2, and includes an operational amplifier 21 and an operational amplifier 21.
The capacitor 22 and the resistor 23 are connected in parallel between the non-inverting input terminal and the output terminal. The charge signal from the yaw rate sensor 6 and the output of the operational amplifier 21 are applied to the non-inverting input terminal of the operational amplifier 21, and the reference voltage Vo is applied to the inverting input terminal. The operational amplifier 21 always operates so that the input charge of the non-inverting input terminal and the voltage determined by the capacitor 22 appear at the output of the operational amplifier 21, and outputs the detection signal B (or C). Therefore, even if the drive signal A is applied to the signal line 4 (or 5) via the resistor 2 (or 3), the drive signal A does not appear on the signal line 4 (or 5) and the detection signal B (Or C) only appears.

The differential amplifier 9 receives a signal from each input terminal and outputs a signal D indicating the difference between the signals. AC amplifier 10 amplifies signal D and outputs signal E. The synchronous detector 11 inverts the signal E every half cycle of the drive signal A,
A signal F is formed and output. The integrator 12 integrates the signal F to form and output a signal G.

The comparator 13 determines which of the signal lines 4 and 5 is disconnected by comparing the level of the signal G with a predetermined positive / negative threshold value. Is output.

FIG. 3 schematically shows the configuration of the yaw rate sensor 6. In FIG. 3, the yaw rate sensor 6
Has an H-shape as a whole, and has a pair of excitation pieces 6.
a, 6b, and a pair of detecting pieces 6c,
A detection tuning fork 6C made of 6d and a support 6D are provided. Each excitation piece 6a, 6b, each detection piece 6c, 6d, and support part 6
D is a quartz plate having a thickness of about 0.3 mm processed by micromachining (etching).

Each excitation piece 6a, 6b of the excitation tuning fork 6A has
The respective excitation electrodes 6e and 6f are deposited, and the detection tuning fork 6
Each of the detection electrodes 6c and 6d of FIG.
g, 6h are deposited. These electrodes 6e, 6f,
6g and 6h are externally connected through the support 6D.

Each excitation electrode 6e, 6 of each excitation piece 6a, 6b
When the drive signal A is added to f, the excitation tuning fork 6A self-oscillates due to the inverse piezoelectric effect of quartz. That is, as shown in FIG. 4A, the respective excitation pieces 6a and 6b vibrate at the excitation speed v along the x-axis. The self-excited oscillation of the excitation tuning fork 6A is called an excitation mode.

In this state, when the yaw rate sensor 6 rotates at the angular velocity ω, as shown in FIG.
A Coriolis force Fc is generated in each of the excitation pieces 6a and 6b, and the respective detection pieces 6c and 6c of the detection tuning fork 6C.
A vibration in the z-axis direction occurs at d. This vibration of the detection tuning fork 6C is called a detection mode.

When the detection tuning fork 6C vibrates in the z-axis direction in this manner, the detection pieces 6c, 6d
Since the detection signals B and C are generated at the detection electrodes 6g and 6h, the detection signals B and C are extracted.

Each detecting piece 6 generated by the Coriolis force Fc
The vibration amplitudes of c and 6d in the z-axis direction are proportional to the amplitudes of the respective excitation pieces 6a and 6b in the excitation mode and the angular velocity ω of the yaw rate sensor 6. Therefore, when the amplitudes of the excitation pieces 6a and 6b are controlled to be constant, the angular velocity of the yaw rate sensor 6 is determined based on the detection signals B and C corresponding to the vibration amplitude of the detection pieces 6c and 6d in the z-axis direction. ω can be detected.

The relationship between the Coriolis force Fc and the angular velocity ω is shown in the following equation (1).

Fc = 2mvω (1) where m is the mass of the vibrating part, and v is the excitation speed.

In the yaw rate sensor 6, since the drive signal A applied to the excitation pieces 6a and 6b leaks to the detection electrodes 6g and 6h of the detection pieces 6c and 6d (crosstalk), the detection signals B and C includes not only a signal component indicating only the angular velocity ω acting on the yaw rate sensor 6 but also a drive signal A. In addition, each excitation piece 6a, 6
Since the vibration of b is transmitted to the detection pieces 6c and 6d and leaks, the detection signals B and C further include a signal component due to the leak vibration. The drive signal A due to such crosstalk and the signal component due to the leakage vibration are removed as described later, and only the signal component indicating only the angular velocity ω acting on the yaw rate sensor 6 is extracted.

FIG. 5 is a timing chart showing the waveform of each signal in the device of the present embodiment. In FIG. 5, the drive signal A is a square wave, and the yaw rate sensor 6
Is applied to the excitation pieces 6a and 6b of the excitation tuning fork 6A to vibrate the excitation pieces 6a and 6b. At this time, a pair of detection signals B and C are sent from the yaw rate sensor 6 to each of the signal lines 4 and 5. These detection signals B and C include the component of the drive signal A generated due to the crosstalk as described above. The components of the drive signal A included in these detection signals B and C are removed by the differential amplifier 9, and a signal E is obtained.

The signal E (shown by a solid line in FIG. 5) is not only a signal component e (shown by a dashed line in FIG. 5) indicating only the angular velocity ω acting on the yaw rate sensor 3 as described above, but also a leak vibration. And a signal component e ′ (shown by a dotted line in FIG. 5), and these signal components e and e ′ are synthesized.

When the signal E is inverted by the synchronous detector 11 every half cycle of the drive signal A, a signal F is obtained. The signal F has a signal component f (indicated by a dashed line in FIG. 5) obtained by inverting a signal component e indicating only the angular velocity ω every half cycle.
A signal component f '(indicated by a dotted line in FIG. 5) obtained by inverting the signal component e' due to the leakage vibration every half cycle is synthesized.

The integrator 12 integrates the signal F and outputs a signal G. When the signal component f ′ included in the signal F is integrated, a level 0 signal component is obtained as a result. Further, when the signal component f included in the signal F is integrated, a signal G indicating only the angular velocity ω acting on the yaw rate sensor 6 is obtained.

That is, the signal F in the synchronous detector 11
The signal component due to the leakage vibration is removed by the inversion of the signal F at each half cycle and the integration of the signal F in the integrator 12, and the signal G indicating only the angular velocity ω acting on the yaw rate sensor 6 can be obtained.

Next, the process of detecting disconnection of each of the signal lines 4 and 5 in the apparatus according to the present embodiment will be described with reference to FIGS.

FIG. 6 is a timing chart showing the waveform of each signal when the signal line 4 is disconnected. When the signal line 4 is broken, the signal line 4 is disconnected from the charge amplifier 7 which always outputs a voltage corresponding to the input signal, so that the detection signal B is not sent out on the signal line 4, and instead, the signal On line 4 the drive signal A applied via resistor 2 appears. Further, the signal line 5 is not disconnected, and the detection signal C appears on the signal line 5.

Here, by appropriately setting the resistance value of the resistor 2, the level of the drive signal A of the signal line 4 is set sufficiently higher than the level of the detection signal C of the signal line 5. Therefore, the differential amplifier 9 outputs a sufficiently high level signal D as the signal D indicating the difference between the signals on the signal lines 4 and 5. The AC amplifier 10 outputs the signal D
And outputs a signal E. Since the signal E is synchronized with the inversion cycle of the synchronous detector 11, the signal F inverted by the synchronous detector 11 has a sufficiently high level D.
The signal becomes a C signal, and the signal G from the integrator 12 also becomes a DC signal having a sufficiently high level. Since the level of the signal G is higher than the positive threshold value, the comparator 13 determines that the line 4 is disconnected, and outputs a signal indicating that the line 4 is disconnected.

The signal G is a DC signal having a sufficiently high level, which is about ten times as large as the level of the signal G when the signal lines 4 and 5 are not disconnected. Therefore, in the comparator 13, the disconnection of the signal line 4 can be reliably determined by appropriately setting the positive threshold value to be compared with the level of the signal G. For example,
Assuming that the level of the signal G when the signal lines 4 and 5 are not disconnected is ± 100 mV, the driving signal A of the signal line 4
Of the signal G is 1500 mV when the signal line 4 is disconnected.
Therefore, by comparing the level of the signal G with an appropriate positive threshold value, it is possible to reliably determine whether or not the signal line 4 is disconnected.

FIG. 7 is a timing chart showing the waveform of each signal when the signal line 5 is disconnected. When the signal line 5 is disconnected, the detection signal C is not sent out on the signal line 5 because the signal line 5 is disconnected from the charge amplifier 7 that always outputs a voltage corresponding to the input signal. On line 5 the drive signal A applied via the resistor 3 appears. Further, the signal line 4 is not disconnected, and the detection signal B appears on the signal line 4.

By appropriately setting the resistance value of the resistor 3, the level of the drive signal A of the signal line 5 is set sufficiently higher than the level of the detection signal B of the signal line 4. , A signal D having a sufficiently high level as a signal D indicating the difference between the signals on the signal lines 4 and 5
Is output. Since the signal D is amplified by the AC amplifier 10 and the amplified signal E is synchronized with the inversion cycle of the synchronous detector 11, the signal F inverted by the synchronous detector 11 becomes a sufficiently high level DC signal. , And the signal G from the integrator 12 is also a sufficiently low level DC signal. Since the level of the signal G is lower than the negative threshold value, the comparator 13 determines that the signal line 5 is disconnected, and outputs a signal indicating that the signal line 5 is disconnected.

For example, assuming that the level of the signal G when the signal lines 4 and 5 are not disconnected is ± 100 mV, it is assumed that the level of the drive signal A of the signal line 5 is appropriately set. When line 5 is disconnected, signal G
Signal level drops to about -1500 mV.
Is compared to the appropriate negative threshold,
It is possible to reliably determine whether or not the signal line 5 is disconnected.

As described above, in the present embodiment, since the drive signal A is applied to each of the signal lines 4 and 5, one of the signal lines 4 and 5 is disconnected, and the disconnected signal line is connected to the charge amplifier. Since the drive signal A appears at the subsequent stage of the differential amplifier 9 when the connection is disconnected from the differential amplifier 9, the disconnection of the signal line can be determined by detecting the drive signal A at the subsequent stage of the differential amplifier 9. In addition, if the level of the drive signal A is set sufficiently higher than the levels of the detection signals B and C, the component of the drive signal A can be easily detected from the output of the differential amplifier 9. It is possible to reliably determine the disconnection of the signal line.

The present invention is not limited to the above embodiment, but can be variously modified. For example, instead of comparing the level of the signal G with a threshold value, regardless of each of the signals D, E, and F at the subsequent stage of the differential amplifier 9,
It is possible to determine whether or not the signal line is disconnected according to the level. Not only the yaw rate sensor, but also a vibration-type sensor, each charge amplifier for inputting a pair of signals from the vibration-type sensor, and any other configuration that differentially amplifies each detection signal from each charge amplifier may be used. The present invention can be applied to various types of sensors.

[0043]

As described above, according to the present invention, a synchronization signal synchronized with a drive signal is added to each signal line transmitting a pair of detection signals, and one of the signal lines is disconnected. Then, the disconnected signal line is disconnected from the charge amplifier, a synchronization signal appears on the disconnected signal line, and a synchronization signal also appears on the output of the differential amplifier. For this reason, any disconnection of each of the signal lines can be determined by detecting the synchronization signal at a stage subsequent to the differential amplifier. Moreover, if the level of the synchronizing signal is set sufficiently higher than the level of each detection signal, it is possible to easily detect the component of the synchronizing signal from the output of the differential amplifying means, and to prevent disconnection of the signal line. The determination can be made reliably.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a disconnection detection device for a vibration type sensor according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a charge amplifier in the device of FIG. 1;

FIG. 3 is a plan view showing a schematic configuration of a yaw rate sensor in the apparatus of FIG.

4A is a diagram illustrating a vibration state of the yaw rate sensor of FIG. 3 in an excitation mode, and FIG. 4B is a diagram illustrating a vibration state of the yaw rate sensor of FIG. 3 in a detection mode.

FIG. 5 is a timing chart showing waveforms of respective signals in the device of FIG.

FIG. 6 is a timing chart showing waveforms of signals when one signal line in the apparatus of FIG. 1 is disconnected.

FIG. 7 is a timing chart showing waveforms of respective signals when the other signal line in the device of FIG. 1 is disconnected.

FIG. 8 is a block diagram showing a conventional device.

9 is a timing chart showing waveforms of respective signals in the device of FIG.

FIG. 10 is a timing chart showing waveforms of signals when one signal line in the device of FIG. 8 is disconnected.

11 is a timing chart showing waveforms of respective signals when the other signal line in the device of FIG. 8 is disconnected.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Excitation circuit 2,3 Resistance 4,5 Signal line 6 Yaw rate sensor 7,8 Charge amplifier 9 Differential amplifier 10 AC amplifier 11 Synchronous detector 12 Integrator 13 Comparator

Claims (1)

[Claims] 1. A vibration sensor that vibrates upon receiving a drive signal and outputs a pair of signals, a charge amplifier that receives a pair of signals from the vibration sensor and outputs each detection signal, A differential amplifying means for differentially amplifying each of the detection signals from each of the charge amplifiers, and detecting a disconnection of each signal line transmitting each of the detection signals based on an output of the differential amplifying means. A disconnection detection device for a vibration-type sensor, comprising: a synchronization signal applying unit that applies a synchronization signal synchronized with the drive signal to each of the signal lines transmitting the detection signals.