JP2018179626A - Ultrasound receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain output data which can be easily analyzed with a compact and low-cost configuration, and to detect an abnormality indicating a sign of a failure of a device in a device diagnostic device. SOLUTION: An acoustic-electrical conversion unit 10 provided with n acoustic-electrical converters 10-I to 10-n having different resonance frequencies f1 to fn, and each signal output from the acoustic-electrical conversion unit 10 are combined. An amplification unit 12 having a rectifying amplifier 12-I to 12-n to be amplified is provided. The acoustic-electric converters 10-I to 10-n have sharp sensitivity peaks at their respective resonance frequencies, and the resonance frequencies are adjusted to the frequencies indicating abnormalities, and the frequencies extracted from the acoustic-electric conversion unit 10 and the amplification unit 12. By analyzing the signal strength pattern, anomalies that are precursors to failure can be accurately detected. The plurality of acoustic-electrical converters are piezoelectric microacoustic-electrical converter arrays manufactured on the same substrate. [Selection diagram] Fig. 1

Description

  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.

  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 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.

  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.

JP, 2011-122853, A

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.

  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.

  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.

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 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

  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.

  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.

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 abnormality, or as a precursor to failure or It is possible to accurately detect an abnormality that indicates a failure state.

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.

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. is, the acoustic-electrical converter 10 is different resonance frequencies _{f 1,} f 2, ..., formed by providing the n-number of acousto-electric transducer 10-I, 10-II ... 10-n having the _{f n.} 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.

FIG. 2 shows an example of the resonance frequencies in an acoustic-electrical conversion unit 10 and is shown, for example, at four acoustoelectric transducer _{10-1~10-4, f 1 = 20kHz, f} 2 = 30kHz, When four resonance frequencies of f ₃ = 40 kHz and f ₄ = 50 kHz are selected, the frequency-sensitivity characteristic as shown in FIG. 2 is 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. .

  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.

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.

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, the resonance frequencies of these acoustoelectric transducer 10-1 to 10-4, as described _{above, f 1 = 20kHz, f 2} = 30kHz, f 3 = 40kHz, described as f 4 = 50 kHz.

  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.

Typical materials of the piezoelectric films 16a and 16b include aluminum nitride (AlN), scandium aluminum nitride (Al _1-x Sc _x N), zinc oxide (ZnO) and lead zirconate titanate (PZT). May be piezoelectric materials other than those illustrated. 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.

The cantilevered diaphragm composed of the piezoelectric films 16a and 16b and the electrode films 17a to 17c has a distance (a length d ₁ to d ₄ in the lateral direction of the diaphragm) from the support and fixed end to the gap g of the opposing portion. When excited by an acoustic signal having a natural frequency determined by the film thickness of the laminated structure of the piezoelectric films 16a and 16b and the electrode films 17a to 17c and material physical constants such as their Young's modulus and density, Vibrate with a large 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.

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 d ₁ of the diaphragm may be 270 μm. D ₂ = 220 μm for the resonance frequency 30 kHz of the acoustoelectric converter 10 -II, d ₃ = 190 μm for the resonance frequency 40 kHz of the acoustoelectric converter 10 -III, and resonance frequency 50 kHz for the acoustoelectric converter 10-IV In this case, d ₄ = 170 μm. Each configuration other than the length _d 1 to d ₄ of the diaphragm of each acoustic-electric converter 10-I~10-IV of FIG. 3 are the same.

  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.

  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.

  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.

1, 10-1 to 10-n: electroacoustic transducer,
2, 12-1 to 12-n ... amplifier,
3 ... A / D converter, 4 ... frequency component calculator (FFT),
10 ... electroacoustic transducer, 10A ... electroacoustic transducer array,
12: amplification unit, 13: wiring,
14 ... silicon substrate, 16a, 16b ... piezoelectric film,
17a to 17c: electrode films, 18a, 18b: electrodes,
20: hole, 22: pattern analysis and abnormality detection unit.

Claims (4)

A plurality of acoustoelectric converters having different resonant frequencies;
And an amplifier connected to the plurality of acoustoelectric transducers,
An ultrasonic wave receiver characterized by extracting ultrasonic wave signal intensity at a frequency indicating abnormality based on outputs of the plurality of acoustoelectric transducers.   2. The ultrasonic receiver according to claim 1, wherein the plurality of acoustoelectric transducers are a piezoelectric microacoustic transducer array fabricated on the same substrate.   3. The ultrasonic receiver according to claim 2, wherein the piezoelectric microacoustic transducer array changes the lengths of the piezoelectric bodies of the plurality of acoustoelectric transducers in response to different resonance frequencies. Used as a receiver of a device diagnostic device that analyzes the pattern of the intensity of the input ultrasonic signal and detects an abnormality of the device,
The ultrasonic wave receiver according to any one of claims 1 to 3, wherein the ultrasonic wave signal intensity at a frequency indicating an abnormality of the device is extracted.

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