JP2018179626

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DESCRIPTION JP2018179626
Abstract: A small-sized, low-cost configuration can obtain easily analyzed output data, and an
apparatus diagnostic apparatus detects an abnormality that indicates a precursor of a failure of
the apparatus. SOLUTION: An acoustoelectric converter 10 provided with n acoustoelectric
converters 10-I to 10-n having different resonance frequencies f1 to fn and respective signals
outputted from the acoustoelectric converter 10 And an amplifying unit 12 having rectifying
amplifiers 12-I to 12-n for amplification. The acoustoelectric converters 10-I to 10-n have sharp
sensitivity peaks at their respective resonant frequencies, and adjust the resonant frequency to a
frequency that indicates an abnormality, and the frequencies extracted from the acoustoelectric
converter 10 and the amplifier 12 By analyzing the pattern of the signal strength, an abnormality
that is a precursor of a failure can be accurately detected. The plurality of acoustoelectric
transducers are piezoelectric microacoustic transducer arrays fabricated on the same substrate.
[Selected figure] Figure 1
Ultrasound receiver
[0001]
The present invention relates to an ultrasonic receiver, and more particularly to an ultrasonic
receiver which is used in an apparatus diagnostic apparatus or the like for detecting a precursor
of failure and which extracts ultrasonic signals of a frequency indicating an abnormality with
high sensitivity.
[0002]
For example, malfunction of equipment (equipment) such as a motor installed in a factory or
various facilities and its precursor are performed by abnormal sound, and a hearing aid is put on
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the ear from a long time, jar Generally, a method is used in which a skilled person listens to
an abnormal noise such as "shasha" and determines the presence or absence of a flaw or contact
of a bearing.
[0003]
Recently, as shown in Patent Document 1 below, a method of using a diagnostic device (sensor
device) instead of a person has been proposed, and this diagnostic device constantly detects
audible sound as shown in FIG. 6, for example. An acoustoelectric converter 1 to be measured is
provided as a sensor, and an electric signal output from the acoustoelectric converter 1 is
amplified by an amplifier 2 and then an A / D converter 3 is used to calculate a frequency
component (FFT) It is input to 4.
The frequency component of the obtained signal is extracted by the A / D converter 3 and the
frequency component calculation unit 4, and the frequency component analysis unit 5 at the next
stage matches the degree of coincidence with the frequency component indicating an
abnormality stored in advance. Is analyzed, and using the analysis result, the abnormality
detection unit 6 detects the presence or absence of an abnormality that is a precursor of a failure
or a failure.
[0004]
JP, 2011-122853, A
[0005]
By the way, there is also experimental data that a malfunction of equipment (equipment) or the
like or an abnormality becoming a precursor thereof does not necessarily appear in an audible
sound, but appears in a so-called ultrasonic region of 20 kHz or more.
However, if it is intended to extend the measurement of abnormality to the ultrasonic region, the
above-mentioned electroacoustic converter 1, A / D converter 3 and frequency component
calculation unit (FFT) corresponding to the ultrasonic wave, because the frequency band of
ultrasonic wave is wide. The burden on 4 becomes heavy and causes cost increase.
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[0006]
The above-mentioned sensor device constantly monitors the status of the device without using a
human hand and detects an abnormality indicating a sign of failure etc. is one of the IoT (Internet
of Things) which can be expected to grow significantly in the future It is a form.
In this IoT, for example, not only acoustic sensors but also various types of sensors that detect
vibration, temperature, current, etc. are attached to all devices in a factory, and time to failure
comprehensively by analyzing the big data It is intended to estimate potential delays, carry out
maintenance with minimal impact on production, and prevent production from stopping due to
catastrophic failure. Therefore, it is desirable that each sensor be as small and inexpensive as
possible, and that the data output from the sensor be easily analyzed.
[0007]
The present invention has been made in view of the above problems, and an object thereof is to
obtain output data which can be easily analyzed with a small size and low cost configuration, and
in the device diagnostic apparatus, it is a precursor of failure of the device. It is an object of the
present invention to provide an ultrasonic wave receiver capable of detecting an abnormality
indicating.
[0008]
In order to achieve the above object, an ultrasonic receiver according to the invention of claim 1
includes a plurality of acoustoelectric transducers having different resonance frequencies, and an
amplifier connected to the plurality of acoustoelectric transducers, It is characterized by
extracting the ultrasonic signal strength in the frequency which shows abnormality based on the
output of a plurality of above-mentioned acoustoelectric transducers.
The invention of claim 2 is characterized in that the plurality of acoustoelectric transducers are
formed on a same substrate into a piezoelectric microacoustic transducer array. The invention
according to claim 3 is characterized in that the piezoelectric microacoustic transducer array
changes the lengths of the piezoelectric bodies of the plurality of acoustoelectric transducers in
response to different resonance frequencies. The invention according to claim 4 is used as a
receiver of a device diagnostic apparatus which analyzes an intensity pattern of an input
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ultrasonic signal to detect an abnormality of the device, and extracts an ultrasonic signal
intensity at a frequency indicating an abnormality of the device. It is characterized by
[0009]
According to the above configuration, the ultrasonic signal strength at a frequency showing an
abnormality (a precursor of a failure or a failure state) is high sensitivity / high signal by a
plurality of acoustoelectric transducers having different resonance frequencies and an amplifier
connected thereto. The noise ratio is extracted. For example, assuming that the Q value of the
resonator that constitutes the acoustoelectric converter is 30, this is equivalent to the sensitivity
being improved by about 30 dB as compared to a wide band acoustoelectric converter having flat
frequency characteristics, and acoustic By adjusting the resonance frequency of the electrical
converter to the abnormal frequency, an abnormal detection signal having high sensitivity and
signal-to-noise ratio can be obtained.
[0010]
According to the present invention, by providing a plurality of acoustoelectric converters having
different resonance frequencies and an amplifier, it is possible to extract ultrasonic signal
strength with high sensitivity and high signal noise ratio at each resonance frequency showing
abnormality. It becomes. Moreover, the amplifier in this case may be narrow band, and the noise
will be reduced accordingly. Furthermore, the ultrasonic acoustic intensity at each frequency can
be easily obtained by smoothing (peak detection) or squaring detection of the output of the
amplifier, and a high speed A / D converter as in the conventional example and an FFT become
unnecessary. It is possible to realize an ultrasound receiver that obtains easily analyzed output
data with a small-sized, low-cost configuration.
[0011]
The acoustoelectric transducers need to be prepared for each frequency to be measured.
However, by forming a plurality of piezoelectric acoustoelectric transducers in the form of an
array on the same silicon substrate, further downsizing and cost reduction are further promoted.
can do. In addition, the resonance frequency of the acoustoelectric converter is matched to the
characteristic frequency of the abnormal sound of the device, and then applied to the device
diagnostic apparatus for analyzing the pattern of the frequency signal strength indicating the
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abnormality, or as a precursor to failure or It is possible to accurately detect an abnormality that
indicates a failure state.
[0012]
It is a circuit diagram showing composition of an ultrasonic wave receiver of an example
concerning the present invention. It is a waveform diagram which shows the frequency
characteristic of the receiving sensitivity in the ultrasonic wave receiver of an Example. It is a top
view which shows schematic structure of the acoustoelectric converter of an Example. It is AA
sectional drawing of the acoustoelectric converter of FIG. It is a circuit diagram showing the
composition when the ultrasonic receiver of an example is applied to a device diagnostic device.
It is a circuit diagram showing composition of a conventional diagnostic device.
[0013]
FIG. 1 shows the circuit of the ultrasonic wave receiver according to the embodiment, and in this
embodiment, as shown in FIG. 1, an acoustoelectric converter (acoustic electric transducer array)
10 and an amplifier 12 are provided. The acoustoelectric converter 10 is provided with n
acoustoelectric converters 10-I, 10-II... 10-n having different resonance frequencies f1, f2,. These
acoustoelectric converters 10-1 to 10-n have sharp sensitivity peaks at their respective resonant
frequencies. Generally, the output impedances of the acoustoelectric converters 10-I to 10-n are
high and the signal strength is small. In order to make the electrical signal easy to handle, in the
amplification unit 12, the rectification amplifiers 12-I to 12-n, which also function as impedance
conversion, are connected to the respective acoustoelectric converters 10-I to 10-n.
[0014]
FIG. 2 shows an example of each resonance frequency in the acoustoelectric converter 10. For
example, in the four acoustoelectric converters 10-1 to 10-4, f1 = 20 kHz, f2 = 30 kHz, f3 =
When four resonance frequencies of 40 kHz and f4 = 50 kHz are selected, frequency-sensitivity
characteristics as shown in FIG. 2 are obtained. This is calculated assuming that the Q value of
each acoustoelectric conversion circuit as a resonator is 30. The sensitivity, which is the
acoustoelectric conversion coefficient at the resonance frequency, can be increased by about Q
times (corresponding to 30 dB at 30 times in the above case) at a resonant frequency as
compared to a wide band acoustoelectric conversion circuit having flat frequency characteristics.
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.
[0015]
In addition, the band of the amplification unit 12 may be a narrow band similar to the band of
the acoustoelectric conversion unit 10 (respective resonators). Therefore, noise can be
suppressed, so that the signal to noise ratio is high. As a result, it is possible to realize an
ultrasonic receiver having an extremely high sensitivity and a signal-to-noise ratio at each
resonance frequency (each acoustoelectric converter). Further, in the embodiment, the output of
the amplification unit 12 (12-1 to 12-n) is smoothed (peak detection) or squared to detect each
resonance frequency of the acoustoelectric converters 10-1 to 10-n. The signal strength of the
ultrasonic wave can be easily obtained, and a high speed A / D converter as in the prior art and a
frequency component calculation means (FFT) are not necessary, and the circuit can be largely
simplified.
[0016]
By the way, in the embodiment, the acoustoelectric converters 10-1 to 10-n are prepared for
each frequency to be measured, but by manufacturing a plurality of piezoelectric acoustoelectric
converters in an array on the same silicon substrate, The features of small size and low cost can
be maintained. Generally, as a piezoelectric type acoustoelectric transducer, a cantilever type in
which one end of a piezoelectric body is supported and fixed, a double-supported beam type in
which both ends are supported and fixed, or a circular diaphragm type in which the entire
peripheral portion is supported and fixed Etc. are known and any of them may be used.
[0017]
FIG. 3 shows an example of a specific configuration of the acoustoelectric converter according to
the embodiment, which includes four acoustoelectric transducers 10-1 to 10-4 having a
cantilever structure on a silicon substrate. It is produced in array form (acoustic electrical
transducer array 10A), and the cross section of one acoustoelectric transducer 10-1 is shown in
FIG. As shown in FIG. 3, each of the acoustoelectric converters 10-1 to 10-4 has a diaphragm
having a rectangular planar piezoelectric film 16 b (and 16 a) as a cantilever structure, and one
pair (two places). The diaphragm is connected by the wiring 13. Further, as described above, the
resonance frequencies of the acoustoelectric converters 10-1 to 10-4 are described as f1 = 20
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kHz, f2 = 30 kHz, f3 = 40 kHz, and f4 = 50 kHz.
[0018]
In FIG. 4, reference numeral 14 is a silicon substrate, 15 is an insulating film, 16a and 16b are
piezoelectric films (piezoelectric materials), 17a to 17c are electrode films, 18a and 18b are
electrodes, and 20 is a hole. That is, in the acoustoelectric transducers 10-1 to 10-4, the
electrode films 17a to 17c and the piezoelectric films 16a and 16b are stacked on the silicon
substrate 14 with the insulating film 15 such as a silicon oxide film interposed therebetween, and
silicon is formed from the back side. It is manufactured by etching the substrate 14 to form the
holes 20, and one end of the diaphragm composed of the piezoelectric films 16a and 16b and the
electrode films 17a to 17c is formed into a cantilever structure as a supporting fixed end to make
a gap g. The diaphragms face each other in the state. This diaphragm is released from the silicon
substrate 14 by the gap g (the gap g between the diaphragm and the gap g between the
diaphragm and the substrate) of the three sides other than the support fixed end as shown in the
plan view of FIG. It is in a state of FIG. 4 is a conceptual view, and the scale in the thickness
direction is different from the scale in the lateral direction.
[0019]
Typical materials of the piezoelectric films 16a and 16b include aluminum nitride (AlN),
scandium aluminum nitride (Al1-xScxN), zinc oxide (ZnO), lead zirconate titanate (PZT), and the
like. Other piezoelectric materials may be used. The crystal orientations indicating the
piezoelectric characteristics of the two piezoelectric films 16a and 16b are the same. For
example, when an acoustic pressure (considering a quasi-DC pressure for explanation) is applied
from the holes 20 of the lower silicon substrate 14, the diaphragm (cantilever) including the
piezoelectric films 16a and 16b is displaced upward. As a result, tensile stress is generated in the
lower layer piezoelectric film 16 b and compressive stress is generated in the upper layer
piezoelectric film 16 a. Since the orientation characteristics are the same, the directions of the
generated potentials are opposite, and based on the intermediate electrode film 17b, voltages of
the same sign are respectively generated in the lower electrode film 17a and the upper electrode
film 17c. The acoustic pressure is applied between the left and right electrodes 18a and 18b by
connecting the electrode films 17a to 17c in the same diaphragm (beam) in parallel by the wiring
13 and the electrodes 18a and 18b and between the diaphragms facing each other in series. The
signal can be taken out as a voltage converted into an electrical signal. In addition, as a material
of each electrode (17a-17c, 18a, 18b), molybdenum (Mo), platinum (Pt), titanium (Ti), iridium (Ir),
ruthenium (Ru), wiring material is aluminum (Al) ), Gold (Au), copper (Cu) or the like.
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[0020]
The cantilevered diaphragm composed of the piezoelectric films 16a and 16b and the electrode
films 17a to 17c has a distance (a lateral length d1 to d4 of the diaphragm) from the support and
fixed end to the gap g of the opposing portion, and the piezoelectric It has a natural frequency
determined by the film thickness of the laminated structure of the films 16a and 16b and the
electrode films 17a to 17c and their material physical constants such as Young's modulus and
density, and is large when excited by an acoustic signal of natural frequency It vibrates in
amplitude. When multiple acoustoelectric transducers (10-I to 10-n) are fabricated on the same
substrate and the material and thickness of the film are fixed, the resonant frequency is adjusted
by the length of the diaphragm (beam) be able to.
[0021]
For example, when the two piezoelectric films 16a and 16b of FIG. 4 are respectively 0.5 .mu.m
thick aluminum nitride, and the film thickness of the electrode films 17a to 17c is sufficiently
thin with respect to the piezoelectric film thickness, the acoustoelectric converter of FIG. In order
to obtain a resonance frequency of 20 kHz at 10-I, the length d1 of the diaphragm may be 270
μm. D2 = 220 μm for the resonance frequency of 30 kHz of the acoustoelectric converter 10-II,
d3 = 190 μm for the resonance frequency of 40 kHz of the acoustoelectric converter 10-III, and
for the resonance frequency of 50 kHz of the acoustoelectric converter 10-IV d4 = 170 μm. In
addition, each structure other than length d1-d4 of the diaphragm in each acoustoelectric
converter 10-I-10-IV of FIG. 3 is the same.
[0022]
In addition, each of the acoustoelectric transducers 10-I to 10-IV of the embodiment is
sufficiently small, and even if four are integrated, it can be accommodated in a chip size of 0.5
mm × 1.5 mm. In addition, since it is the same except for the length of the diaphragm, there is
no increase in the number of processes. Therefore, by manufacturing a plurality of piezoelectric
type acoustoelectric transducers in the form of an array on the same silicon substrate, a compact
and low-cost ultrasonic receiver can be obtained.
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[0023]
FIG. 5 shows the configuration in the case where the ultrasonic wave receiver according to the
embodiment is applied to a device diagnostic apparatus. In this case, the latter stage of the
amplification unit 12 connected to the acoustoelectric conversion unit 10 described in FIG. Are
connected to a pattern analysis and abnormality detection unit 22 that analyzes (or recognizes) a
pattern of ultrasonic signal intensity at a frequency that indicates an abnormality.
[0024]
According to such a configuration, the respective outputs obtained by the respective
acoustoelectric converters 10-1 to 10-n of the acoustoelectric converter 10 are amplified by the
amplifiers 12-1 to 12-n of the amplifier 12. The output signals of the amplifiers 12-1 to 12-n are
subjected to pattern analysis.
That is, the frequency extracted by the acoustoelectric converters 10-1 to 10-n is matched with
the characteristic frequency of the abnormal sound of the device evaluated and determined in
advance, and the output of the acoustoelectric converters 10-1 to 10-n By comparing and
analyzing the amplified ultrasonic signal with the intensity pattern of the frequency of the
abnormal sound, an abnormality that is a precursor of (or in a failure state of) a device failure is
detected. In addition, it is possible to enhance the detection accuracy of the abnormality which is
a precursor of the failure by comprehensively judging together with the sensors other than the
ultrasonic wave such as the temperature and the vibration.
[0025]
1, 10-1 to 10-n: electro-acoustic transducer, 2, 12-1 to 12- n: amplifier, 3: A / D converter, 4:
frequency component calculator (FFT) 10: electro-acoustic transducer Sections 10A:
electroacoustic transducer array 12: amplification portion 13: wiring 14: silicon substrate 16a,
16b: piezoelectric film 17a to 17c: electrode film 18a, 18b: electrode 20: hole 22 ... pattern
analysis and anomaly detection unit.
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