JPH08327363A - Angular velocity sensor - Google Patents

Abstract

PURPOSE: To detect a failure of sensor and to enhance reliability of a monitor by a constitution wherein a mechanical connection signal except an angular velocity output obtained from a detection body is designated as a monitor signal. CONSTITUTION: It is hard to make sizes of piezoelectric elements 13a, 14a and the ways of attaching the same, and as the result, mechanical connection signals are always generated from the elements 13a, 14a. The elements 13a, 14a are attached to the identical sides of detection plates 13, 14 respectively, and since centroids of the plates 13, 14 are slightly shifted to the sides where the elements 13a, 14a are attached, when drive plates 11, 12 vibrate as a tuning fork, they are bent toward the sides of elements 13a, 14a to be widened. Therefore, since mechanical connection signals generated on the elements 13a, 14a have the phases reversed to each other, the mechanical connection signals at a D point are synthesized to be suppressed. The synthesized mechanical connection signal is amplified by a change amplifier 20 and an amplifier 25, rectified by a rectifier 26 and smoothed by a smoother 27, then the level thereof is judged by a judgment device 28. The judgment result is outputted from a monitor signal terminal 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor.

[0002]

2. Description of the Related Art For example, a tuning fork type angular velocity sensor is provided with a detection plate at the tip of both drive plates of a tuning fork type drive section in a direction orthogonal to the drive plates, and the angular velocity is kept constant while the drive plates are constantly driven. When added, the angular velocity is detected by the output from the detection plate which vibrates in the opposite directions in response thereto.

[0003]

A problem in the above-mentioned conventional example is a function of detecting whether or not the characteristics reach stable operation after the sensor is activated, or an attachment body of an angular velocity sensor, for example, a vehicle. As a result of a large impact such as a collision with a part of the part, the part is damaged and a normal detection operation cannot be performed. Therefore, the present invention makes it possible to detect a state in which a part of the angular velocity sensor is damaged and a normal detection operation cannot be performed,
Moreover, since the timing at which the output stabilizes after the activation of the sensor can be detected, the purpose is to enable quicker use than before.

[0004]

In order to achieve this object, the present invention relates to a vibrating portion, a driving means for driving and vibrating the vibrating portion, and a detection body including a detecting means for detecting an angular velocity, and this detection means. An output terminal for extracting an angular velocity output from the body is provided, and a mechanical coupling signal other than the angular velocity output obtained from the detection body is detected and used as a monitor signal.

[0005]

With the above configuration, by using the mechanical coupling signal that is always obtained from the detector as the monitor signal in the configuration,
It becomes possible to detect whether or not this angular velocity signal is in a state in which normal detection operation is possible, and since the mechanical coupling signal is always generated, a means for generating this mechanical coupling signal should be provided. Not only it does not have to be provided separately, but its configuration is extremely simple and reliable for the monitor.
After the sensor is activated, the timing at which the characteristics become stable can be known, and the sensor output can be used sooner after the activation.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a case made of resin and having one end opened, and a lid 2 made of resin is attached to the opening of the case 1 to form a sealed space.

Inside the sealed space, the circuit board 3 and
A weight plate 4 made of metal is stored. That is, the support pins 5 are planted at the four inner corners of the case 1, and the weight plate 4 and the circuit board 3 are elastically supported and fixed by the support pins 5. In order to elastically support the weight plate 4, dampers 6 made of rubber are attached to the four corners, and support legs 7 made of resin are provided between the damper 6 and the circuit board 3, and the support pins 5 are provided. Has penetrated the damper 6, the support leg 7, and the circuit board 3 from below, and its tip is crushed toward the circuit board 3 side, whereby the circuit board 3 and the weight plate 4 are elastically supported and fixed. . As shown in FIG. 2, metal support pins 8 are vertically press-fitted and fixed to the weight plate 4 on the circuit board 3 side, and metal support pins 8 are horizontally supported on the support pins 8 in the horizontal direction. One end of the pin 9 is press-fitted and fixed. The diameter of the support pin 9 is as small as about one fifth of the diameter of the support pin 8, and the material is made of a metallic material having a spring property such as a piano wire.
A metal substrate 10 is fixed to the other end by soldering.

One end of metal drive plates 11 and 12 is fixed on both sides of the support pin 8 and 9 of the substrate 10, and plate-shaped piezoelectric elements 11a and 12a are fixed to the surfaces thereof. Thereby forming a tuning fork-shaped drive unit.
Further, as shown in FIG. 2, the other ends of the drive plates 11 and 12 are bent in a direction orthogonal to the piezoelectric elements 11a and 12a, and then the detection plates 13 and 14 formed by extension are plate-shaped piezoelectric elements 13a and 13a. 14a is fixed, and the detector is configured by this.

FIG. 3 shows a control circuit, in which the piezoelectric element 11a of the driving plate 11 has a voltage of about 1 V _PP , 1.5 kHz from the driver 15.
An AC signal of z is applied. As a result, the drive plate 11,
At 12, a tuning fork vibration starts inward and outward with respect to the support pin 9. A voltage proportional to the applied signal is induced in the piezoelectric element 12a of the drive plate 12 by the tuning fork vibration, which passes through the current amplifier 16 and the bandpass filter 17 and becomes the signal A in FIG. This is followed by full wave rectifier 18, AGC circuit 1
It is fed back to the driver 15 via 9, and the AGC control of the drive signal is performed. In the detection unit, when the piezoelectric elements 13a and 14a detect the angular velocity, the piezoelectric elements 13a and 14a both output an angular velocity signal of + Q, which is shown in FIGS. 4B and 4C as the angular velocity signal.
This is synthesized at point D in FIG. 3 and becomes an angular velocity signal as shown in D in FIG. This angular velocity signal is then output from the output terminal 24 via the charge amplifier 20, the bandpass filter 21, the synchronous detection 22, and the lowpass filter 23.
The signal waveforms at points E, F, and G in the meantime are E, F, and
It is shown in G as an angular velocity signal.

In the present embodiment, the drive plates 11,
Although the detection plates 13 and 14 must be provided in a direction orthogonal to the position 12, it is practically difficult to make this a true orthogonal direction, and the size of the piezoelectric elements 13a and 14a and the mounting method thereof are completely different. Since they cannot be the same, as a result, the mechanical coupling signals shown in B and C of FIG. 4 are always generated from the piezoelectric elements 13a and 14a. In this case, the piezoelectric elements 13a and 14a are attached to the same surface of the detection plates 13 and 14, and the centers of gravity of the detection plates 13 and 14 are slightly shifted to the attachment sides of the piezoelectric elements 13a and 14a, so that the drive plates 11 and 12 are tuned. When it vibrates, for example, when it spreads outward, it flexes and spreads toward the piezoelectric elements 13a and 14a. Therefore, the mechanical coupling signals generated in these piezoelectric elements 13a and 14a are in the opposite phases as shown in B and C of FIG. 4, and therefore, when the mechanical coupling signals are combined at point D of FIG. The mechanical coupling signal is small. The mechanical coupling signal is amplified by the charge amplifier 20 and the amplifier 25, rectified by the rectifier 26, smoothed by the smoother 27, and then level-determined by the determiner 28, and the determination result is output from the monitor signal terminal 29. To be done. H, I, in FIG.
The output of each J point is shown in FIG. That is, when the output I of the smoother 27 is between a and b, the output of the monitor signal terminal 29 becomes a low level as indicated by J in FIG. On the other hand, for example, when the detection plate 14 shown in FIG. 3 is damaged or its lead wire is broken, both the angular velocity signal and the mechanical coupling signal become zero level, as shown in C of FIG. As a result, at point D, a mechanical coupling signal is generated only from the piezoelectric element 13a, and the mechanical coupling signal level becomes much higher than before. Therefore, at this time, the output of the smoother 27 becomes larger than the point a as shown by I in FIG. 4, and as a result, the decision unit 28 produces a high level output as shown by J in FIG. When both the detection plates 13 and 14 are damaged or both lead wires are broken, the output of the smoother 27 is smaller than the point b of I in FIG. 4, and the output of the determiner 28 is high at this time as well. It will output the level. When such a high level output is output, it is determined that the angular velocity sensor has failed and information is transmitted to the device used.

FIG. 5 shows another embodiment. In this embodiment, a synchronous detector 30 is provided between an amplifier 25 and a smoother 27.
, The synchronous detection is performed by the feedback signal of the drive signal feedback circuit, that is, the signal from the point A in FIG. That is, since the angular velocity signal is also mixed in the mechanical coupling signal flowing into the amplifier 25, this angular velocity signal is canceled to bring the mechanical coupling signal level close to an accurate value. Therefore, as described above, the signal of A in FIG. 6 flowing to the point A in FIG. 5 is delayed by 90 degrees in the phase shifter 31, and the output from the amplifier 25 is synchronously detected by the signal having the 90 degree phase delay. For example, the angular velocity signal is canceled as shown by I in FIG.
The mechanical coupling signal level can be brought close to an accurate value.

FIG. 7 shows another embodiment. In this embodiment, as an initial setting, the mechanical coupling signals obtained from the piezoelectric elements 13a and 14a are set to 0 when added at point D in FIG. It is a thing. That is, while the addition shown in FIGS. 3 and 5 is in a state other than 0, in this embodiment, the detection plates 13 or 14 are trimmed to generate the piezoelectric elements 13a and 14a. The sum of the mechanical coupling signals is initialized to 0. FIG. 8D shows that, for example, the mechanical coupling signal is not generated until the detection plate 14 is damaged or the lead wire is disconnected. However, after this failure, the mechanical coupling signal is not generated from the piezoelectric element 14a, so that the mechanical coupling signal appears as shown in D of FIG. As a result, as shown in J of FIG. 8, the output of the determiner 28 becomes high level, and this is a signal from the monitor signal terminal 29 via the logical sum circuit 32 to inform that the angular velocity sensor has failed as shown in L of FIG. Will be output. Further, in the present embodiment, the feedback signal of the drive signal, that is, the output of the full-wave rectifier 18 is supplied to the OR circuit 32 via the determiner 33. this is,
In the present embodiment, the purpose is to notify the failure from the monitor signal terminal 29 even when the drive plates 11 and 12 are not driven. Therefore, in the present embodiment, the drive signal is supplied to the logical sum circuit 32 through the judging device 33, and the judging device 33 outputs a high level when the feedback signal is 0, which is a logical value. The failure can be notified by being output from the monitor signal terminal 29 via the summing circuit 32. FIG. 9 shows another embodiment. Also in this embodiment, the detection plate 13 or 14 is trimmed and initialized so that it becomes 0 when the mechanical coupling signals obtained from the piezoelectric elements 13a and 14a are added. The signal from the piezoelectric element 13a is amplified by the charge amplifier 20a, the signal from the piezoelectric element 14a is amplified by the charge amplifier 20b, and the signals obtained by adding them by the adder 34 are output from the output terminal 24 from the angular velocity output. Is taken out as. Further, the subtractor 35 subtracts the output of the charge amplifier 20b from the output of the charge amplifier 20a, and the subsequent processing outputs the monitor signal from the monitor signal terminal 29 as a monitor signal. The waveform of each part is shown in FIG. Although some examples have been shown in the above embodiment, the amplifier 2
5, the rectifier 26 and the smoother 27 may be omitted. Also, I explained using a tuning fork type angular velocity sensor, but it is a triangular prism type,
Since the mechanical coupling signal is always generated in the cylindrical type, the sound piece type, and the cylindrical type angular velocity sensors, the failure can be detected using the mechanical coupling signal.

[0013]

As described above, according to the present invention, the vibrating portion, the driving means for driving and vibrating the vibrating portion, and the detecting body including the detecting means for detecting the angular velocity, and the output terminal for extracting the angular velocity output from the detecting body. And a mechanical coupling signal other than the angular velocity output obtained from the detection body is detected and used as a monitor signal. With the above configuration, it is possible to detect whether or not this angular velocity signal is in a state where normal detection operation can be performed by using the mechanical coupling signal obtained from the detection body as a monitor signal without fail in the configuration. In addition, since the mechanical coupling signal is always generated, it is not necessary to separately provide a means for generating the mechanical coupling signal, and the configuration is extremely simple for that, and the monitor is highly reliable. can do.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a main part of FIG.

3 is a control circuit diagram of FIG.

FIG. 4 is a waveform diagram of FIG.

FIG. 5 is a control circuit diagram of another embodiment of the present invention.

6 is a waveform diagram of FIG.

FIG. 7 is a control circuit diagram of still another embodiment of the present invention.

8 is a waveform diagram of FIG. 7.

FIG. 9 is a control circuit diagram of still another embodiment of the present invention.

10 is a waveform diagram of FIG.

[Explanation of symbols]

 11 Drive Plate 11a Piezoelectric Element 12 Drive Plate 12a Piezoelectric Element 13 Detection Plate 13a Piezoelectric Element 14 Detection Plate 14a Piezoelectric Element 24 Output Terminal 29 Monitor Signal Terminal

Claims (12)

[Claims] 1. A detection body comprising a vibrating portion, a driving means for driving and vibrating the vibrating portion, and a detection means for detecting an angular velocity, and an output terminal for extracting an angular velocity output from the detection body. An angular velocity sensor that detects mechanical coupling signals other than the obtained angular velocity output and uses them as monitor signals. 2. The detector according to claim 1, wherein the detector is composed of a tuning fork-shaped drive portion and a detection plate provided at the tips of both drive plates constituting the drive portion in a direction orthogonal to the drive plates. Angular velocity sensor. 3. The angular velocity sensor according to claim 1, wherein the vibrating portion is made of a material having piezoelectricity. 4. The angular velocity sensor according to claim 2, wherein a mechanical coupling signal resulting from mechanical coupling between the sensing plate and the drive plate is detected from the sensing plate and used as a monitor signal. 5. The angular velocity sensor according to claim 4, wherein a mechanical coupling signal component is detected from a signal obtained from the output terminal and is used as a monitor signal. 6. The angular velocity sensor according to claim 1, wherein the decrease in the level of the mechanical coupling signal is detected and used as a monitor signal. 7. The angular velocity sensor according to claim 4, wherein the mechanically coupled signals obtained from the two detectors are amplified by a charge amplifier, rectified, smoothed, and then supplied to a determination circuit. 8. The angular velocity sensor according to claim 6, wherein the sum of the mechanical coupling signals obtained from the two detectors is initialized to a predetermined value other than zero. 9. The angular velocity sensor according to claim 7, wherein the sum of mechanical coupling signals obtained from the two detection plates is initialized to 0. 10. The angular velocity sensor according to claim 9, wherein the determination circuit output of the drive section and the monitor signal output are supplied to an OR circuit. 11. The sum of mechanical coupling signals obtained from two detection plates is initialized to a predetermined value other than 0, and the mechanical coupling signals obtained from these detection plates are amplified by a charge amplifier. 5. The structure in which the mechanically coupled signal amplified by the signal is synchronously detected by a signal obtained by phase-converting a feedback signal flowing through a feedback circuit of a drive signal by a 90-degree phase shifter, and smoothed, and then supplied to the determination circuit.
Or the angular velocity sensor described in 5 or 6. 12. The sum of the mechanical coupling signals obtained from the two detection plates is initialized to 0, and the mechanical coupling signals obtained from the two detection plates are amplified by different charge amplifiers, respectively, and these different charge amplifiers are amplified. The angular velocity sensor according to claim 4, wherein the signal obtained by subtracting the output of (1) is rectified and smoothed, and then supplied to the determination circuit.