WO2008001798A1

WO2008001798A1 - Oscillating wave detection method and device

Info

Publication number: WO2008001798A1
Application number: PCT/JP2007/062863
Authority: WO
Inventors: Shigeru Ando; Nobutaka Ono; Yuya Fujita; Naoki Ikeuchi
Original assignee: The University Of Tokyo; Tokyo Electron Limited
Priority date: 2006-06-27
Filing date: 2007-06-27
Publication date: 2008-01-03
Also published as: TW200809169A; JP2008008683A; WO2008001798B1

Abstract

Provided are an oscillating wave detection method and device capable of obtaining a Hilbert transform pair output as an instantaneous value in real time. The oscillating wave detection method causes an oscillating wave to propagate to a plurality resonance beams (51 to 5m), each resonating to a particular frequency, and detects oscillation of each of the resonance beams (51 to 5m) as an electric signal by using piezoelectric resistors (61 to 6m) arranged in the resonance beams (51 to 5m). The resonance beams (51 to 5m) are arranged so that positions of the respective resonators are arranged in a logarithmic linear form proportional to a logarithm of their resonance frequencies. When N is an integer not smaller than 2, the resonance beams (51 to 5m) are selected by every other N-1 and the outputs of the piezoelectric resistors (61 to 6m) are added so as to output a plurality of signals. More preferably, the N is an integer not smaller than 3 and the resonance beams (51 to 5m) are arranged and the resonance frequencies are set so that the ratio of the resonance frequencies of the resonance beams (51 to 5m) of every other N-1 is constant.

Description

Specification

Vibration wave detection method and apparatus

Technical field

The present invention relates to a vibration wave detection method and apparatus for detecting the intensity of vibration waves for each frequency band.

Background art

Non-Patent Document 1 and Non-Patent Document 2 disclose resonator array type vibration sensors that detect the intensity of vibration waves for each frequency band. This vibration sensor includes an array of resonators having different resonance frequencies. Each resonator resonates with the frequency component of the resonance frequency of its own resonator among the frequency components of vibration waves such as sound waves. This vibration sensor converts the resonance level of each resonator into an electrical signal and outputs it.

[0003] In a conventional vibration sensor, a piezoresistor is formed near the support portion of the resonator, and a change in the resistance value of the piezoresistor caused by the vibration (resonance) of the resonator is detected by a Wheatstone bridge or the like. Thus, an electrical output signal is extracted from the resonator. The sensor described in Non-Patent Document 2 switches the multiplexer to obtain the Wheatstone bridge output signal at each resonator.

[0004] Patent Document 1 and Patent Document 2 propose a method of controlling the gain of a specific frequency band with a simple circuit configuration of a resonator array type. For example, in the technique described in Patent Document 1, in a resonator array type vibration sensor, each piezoresistor provided in each resonator is connected in parallel. By changing the resistance value by changing the power voltage applied to the parallel circuit or changing the shape of the piezoresistor, the gain in a specific frequency band is controlled.

[0005] Further, the technique described in Patent Document 2 utilizes the fact that the magnitude of distortion varies depending on the position of the resonator. That is, the gain of a specific frequency band is controlled by adjusting the position where the piezoresistor is provided in each resonator so that the level of the output signal in each frequency band becomes a desired level.

Non-specific 3 pm Reference 1: W. Benecke et al., A Frequencv-eiective, Piezoresistive Silicon Vi bration Sensor, "Digest of Technical Papers of TRANSDUCERS '85, pp. 105-108 (1 985)

Non-Patent Document 2: E. Peeters et al., "Vibration Signature Analysis Sensors for Predictive Diagnostics," Proceedings of SPIE, 97, vol. 3224, pp. 220-230 (1997)

Patent Document 1: JP 2000-46639 A

Patent Document 2: Japanese Patent Laid-Open No. 2000-46640

Disclosure of the invention

Problems to be solved by the invention

[0006] When dealing with vibration phenomena and acoustic signals, expressing a signal as a complex number enables various analyzes and conversions such as instantaneous amplitude / phase detection and signal modulation / demodulation. Conventional acoustic / vibration sensors such as microphones are devices that convert physical quantities such as sound pressure at each time into electrical signals, and the output is a single real signal. In general, in order to convert a real signal into a corresponding complex signal, it is necessary to perform an operation called the Hilbert transform described below. This operation is non-causal and cannot be performed in real time on wideband signals. For this reason, the complex number representation of signals can only be applied to narrow-band signals that are handled in the communications field.

[0007] Generally, there is a relationship of the following Hilbert transform between the real part and the imaginary part of the analytic function.

A regular function in the upper half plane (y≥0) of complex variable z = x + jy, where imaginary unit is j, Φ (z) = U (x, y) + jV (x, y)

Boundary value on the real axis of

f (x) = U (x, 0), g (x) = -V (x, 0)

There is a relationship shown in Eq. (1) when f and g are real integral functions (f, g ^ Ll (one ∞, ∞)).

[Number 1]

Here, p. V means the main value of Cauchy as shown in equation (2).

[0008] Let g be a Hilbert transform of f, and let f and g be a Hilbert transform pair. The hinorebenore transformation is a function that connects the real and imaginary parts of the analytic function.

[0009] It is convenient to analyze physical phenomena, particularly vibration phenomena, on a complex plane. In general, vibration phenomena are characterized by time-varying amplitude and phase. The instantaneous amplitude and phase at each time are defined as the absolute value and declination of the complex signal expressed in real and imaginary parts based on Euler's formula = cos Θ + jsin Θ. Therefore, in order to grasp the phenomenon from the instantaneous value, it is not sufficient to know only the real part or the imaginary part, and it is necessary to know both the real part and the imaginary part.

[0010] Since the relationship between the real part and the imaginary part forms a Hilbert transform pair, the other can be derived by the above g or f expression. However, since the equations for g and f are expressed as time integrals in the interval (-∞, ∞) as shown in Equation (1), it is necessary to observe a certain period (at least one period in the periodic function). is there. Conventional vibration wave detection devices can detect only one piece of information, and thus cannot obtain both real part and imaginary part information in real time.

[0011] For example, as shown in Patent Document 1, a dynamically changeable frequency characteristic is realized by applying a negative voltage of a piezoresistive detector according to the resonance frequency of the resonator. However, with the conventional method, the load for vibration wave detection is limited to positive and negative real numbers, and the Hilbert transform versus output cannot be obtained in real time as instantaneous values.

[0012] The present invention has been made in view of such circumstances, and its purpose is to instantaneously The object is to provide a vibration wave detection method and apparatus capable of obtaining a Hilbert transform versus output as a time value.

Means for solving the problem

[0013] The vibration wave detection method according to the first aspect of the present invention includes:

A vibration wave detecting method for propagating vibration waves to a plurality of resonators that resonate at different specific frequencies and detecting vibrations of each of the resonators,

The plurality of resonators are arranged so that the positions of the respective resonators are logarithmic linear proportional to the logarithm of their resonance frequencies,

It is characterized in that N is an integer of 2 or more, N− every other resonator is selected, and the outputs of the detectors are added to output a plurality of signals.

[0014] The vibration wave detection device according to the second aspect of the present invention provides:

A resonator array in which a plurality of resonators resonating at specific frequencies different from each other are arranged IJ so that the position of each resonator is logarithmically linear in proportion to the logarithm of the resonance frequency, and

A detector for detecting the vibration of each of the plurality of resonators by the vibration wave propagated to the resonator array;

A plurality of output synthesizers that select the plurality of resonators every N_ 1 and add the outputs of the detectors, where N is an integer greater than or equal to 2,

It is characterized by providing.

The invention's effect

According to the vibration wave detection method and vibration wave detection apparatus of the present invention, it is possible to obtain a Hilbert transform pair output as an instantaneous value in real time (without performing an operation on data for a certain period).

Brief Description of Drawings

FIG. 1 is a diagram showing an example of a sensor body in a vibration wave detection device of the present invention.

FIG. 2 is a circuit diagram showing an example of a vibration wave detection apparatus of the present invention.

FIG. 3 is a diagram schematically showing frequency characteristics of a resonant beam of the sensor body.

[Fig.4] Shows an example of the sensor body in the case where a resonant beam is provided on both sides of the transverse beam FIG.

FIG. 5 is a circuit diagram showing an example of a vibration wave detection device of the present invention using the sensor body of FIG.

FIG. 6 is a circuit diagram showing an example of a vibration wave detection device of the present invention when the detector is a capacitor.

FIG. 7 is a diagram showing an example of a vibration wave detection device in which a resonance beam is provided on both sides of a transverse beam and the detector is a capacitor.

FIG. 8 is a circuit diagram showing an example of a piezoresistive vibration wave detector that outputs the sum of the outputs of the respective resonant beams.

FIG. 9 is a circuit diagram showing an example of a piezoresistive vibration wave detector using a plurality of bias voltage lines.

Explanation of symbols

[0017] 1 Sensor body

2 Diaphragm

3 Cross beam

4 End plate

51, 52, 53, 54, 5m, 51a, 51b, 52a, 52b, 5na, 5nb, 5ma, 5mb & 61, 62, 63, 64, 6m, 61a, 61b, 62a, 62b, 63a, 63b, 6ma, 6mb piezoresistors 7a, 7b power supply

81, 82, 83, 8n, 8m, 81a, 81b, 82a, 82b, 83a, 83b, 8ma, 8mb

91, 92, 93, 9n, 9m, 91a, 91b, 92a, 92b, 93a, 93b, 9ma, 9mb

10a, 10b, 10c operational amplifier

20 Semiconductor silicon substrate

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated. An acoustic sensor that uses sound waves as vibration waves to be detected will be described below as an example.

FIG. 1 is a diagram showing an example of a sensor body in the vibration wave detection device of the present invention. Half The sensor body 1 formed on the conductive silicon substrate 20 includes a diaphragm 2 that receives sound waves, a transverse beam 3 that is connected to the diaphragm 2, a stop plate 4 that is connected to the tip of the transverse beam 3, and a transverse beam 3 5m (hereinafter collectively referred to as resonant beam 5), all of which are formed of semiconductor silicon. Yes.

[0020] The width of the transverse beam 3 is thickest at the end on the diaphragm 2 side, and then gradually narrows toward the end plate 4 side according to the direction force, and is narrowest at the end on the end plate 4 side. In FIG. 1, Zn indicates the width of the transverse beam 3 at the position where the nth resonance beam 5n is supported. Each resonant beam 5 is a resonator whose length is adjusted so as to resonate at a specific frequency.

The plurality of resonant beams 5 are selectively oscillated in response to the resonant frequency f expressed by the following equation (3).

Where C is a constant determined experimentally

a: Thickness of each resonant beam 5

X: Length of each resonant beam 5

Y: Young's modulus of material (semiconductor silicon)

s: Density of material (semiconductor silicon)

As can be seen from the above equation (3), by changing the thickness a or the length X of the resonant beam 5, the resonant frequency f can be set to a desired value. Each resonant beam 5 has a unique resonant frequency. In this example, the thickness a of all the resonant beams 5 is constant, and the length X of the resonant beams 5 is made to increase gradually from the right side (diaphragm 2 side) to the left side (end plate 4 side). That is, from the right side (diaphragm 2 side) to the left side (end plate 4 side) The resonant frequency at which each resonant beam 5 inherently vibrates with increasing force is set from a high frequency to a low frequency.

The position of each resonance beam 5 in the sensor body 1 is proportional to the logarithm of the resonance frequency of the resonance beam 5. This is called a log-linear structure. The resonant beams 5 are configured to be arranged at equal intervals. That is, the ratio of the resonance frequencies of the adjacent resonance beams 5 is constant for any resonance beam 5. The sensor body 1 configured in this way is called a fishbone sensor.

[0024] Since the fishbone sensor has a logarithmic linear structure, the shape from the position of the resonance beam 5 of the transverse beam 3 to the shape of the resonance beam 5 in any resonance beam 5 is the same structure (self (Similar). In addition, the traveling speed of the vibration wave transmitted through the transverse beam 3 is proportional to the frequency, and the wavelength is constant regardless of the frequency.

Note that the sensor main body 1 having the above-described configuration is manufactured on the semiconductor silicon substrate 20 by using a micromachine cache technique. The vibration energy input from the diaphragm 2 is distributed to the respective resonant beams 5 through the transverse beams 3, absorbed by the mechanical-electric converters of the respective resonant systems, converted into signal energy, and extracted.

FIG. 8 is a circuit diagram showing an example of a conventional piezoresistive vibration wave detection device that outputs the sum of the outputs of the respective resonant beams 5 using the sensor body 1. In the circuit of FIG. 8, a positive DC bias is applied to the upper resonance beams 51a to 5ma, a negative DC bias is applied to the lower resonance beams 51b to 5mb, and the current force of each resonance beam 5 is Added and output. Here, for ease of understanding, it is assumed that the upper and lower resonant beams 5 that make a pair vibrate in opposite phases, and the upper and lower piezoresistors 6 expand and contract in opposite phases.

In FIG. 8, the resistance value of the piezoresistor on the i-th upper resonant beam is R + δ R (t), and the resistance value of the piezoresistor on the i-th lower resonant beam is R _ δ R (t), upper and lower each

i i

If the voltage applied to one common terminal of the resistor is V or -V, the other common terminal

0 0

The current flowing into the virtual ground point of the operational amplifier is expressed by the following equation (4).

[Equation 4] I =

_{= 1} R-8 R _{

[0028] Then, it is taken out by the feedback resistor R as an oscillating voltage represented by the following equation (5).

f

[Equation 5] (2R _f V ₀ , (δ Ι¾ ω, / S Ri (t), _{f λ} i = i. R no \ Ri no j ¹ \ R-The combined output load W adjusts the resistance R But it is actually variable

i i

It becomes fixed by trimming at the time of chip manufacture.

It is conceivable to change the bias voltage for each resonant beam 5 by utilizing the fact that the output is proportional to the bias voltage V 0 by the above method. FIG. 9 is a circuit diagram showing an example of a conventional piezoresistive vibration wave detector using a plurality of noise voltage lines. Using the circuit in Fig. 9, dynamic gain adjustment by frequency is possible. If the bias voltage of the i-th resonant beam is soil V, the output voltage V is expressed by the following equation (6).

1 out

圆. _ut , 2R _f V _i X (S Ri (t), S Ri (t), _r , v-

(6)

However, since the number of wirings that can be passed through the transverse beam 3 is limited, when the number of the resonance beams 5 increases, bias control in which the resonance beams 5 are grouped becomes necessary.

The vibration wave detection device shown in FIG. 9 has variable frequency characteristics, but the gain that can be set for each frequency is limited to a real number. The gain in frequency filtering becomes real or pure imaginary only when the impulse response is symmetric or anti-symmetric. If the gain set for each frequency is limited to a real number, an arbitrary impulse response cannot be realized. Fig. 8 or Fig. 9 In any of the vibration wave detectors shown in Fig. 1, the output is limited to the real part, and the output of the Hilbert transform pair cannot be obtained.

[Embodiment 1]

FIG. 2 is a circuit diagram showing an example of the vibration wave detection apparatus of the present invention using the sensor body 1. Piezoresistors 61, 62, and 6m (hereinafter collectively referred to as piezoresistors 6) are formed in the distortion generating portions (crossing beam 3 side) of each resonance beam 5 of the sensor body 1. The plurality of piezoresistors 6 are connected in parallel, and one end of the piezoresistor 6 is connected to a power source 7a having a bias voltage V.

0

[0033] The other end of the piezoresistor 6 is connected to the input terminal of operational amplifiers 10a, 10b, and 10c (hereinafter collectively referred to as operational amplifier 10) by a common line every other N_1, where N is a positive integer. It is connected. That is, the current outputs from the piezoresistors 6 having the same number of N remainders (modulo) are added and input to different operational amplifiers 10 respectively. Such a configuration is called the N-phase addition method. In Fig. 2, N is 3, and the other end of the piezoresistor 6 is connected to a common line every 3 – 1 = 2. That is, the piezo resistors 61, 64,... Are connected to the operational amplifier 10a and the piezo resistors 6

2 is connected to the operational amplifier 10b, and the piezoresistors 63,... Are connected to the operational amplifier 10c.

The transfer impedance type operational amplifier 10 is a current-voltage conversion amplifier having an input impedance of 0 and an output impedance of 0. The + input terminal of the operational amplifier 10 is grounded. The common line connected every other N—is connected to the negative voltage—V power supply 7b through a dummy resistor Rd.

0

Next, the operation of the vibration wave detection device shown in FIG. 2 will be described. Let the frequency characteristic of the nth resonant beam on the logarithmic frequency axis be F (Ω). Where Q = log c represents the logarithmic frequency. Since the sensor body 1 has a logarithmic linear structure, it is assumed that the frequency characteristics of the resonance beam and all the resonant beams can be expressed as shown in Equation (7) using a common characteristic shape F (Q). .

[Equation 7]

F (Ω) = F (Q -n AΩ) (7) However, ΔΩ represents the logarithm of the resonance frequency ratio between adjacent beams.

FIG. 3 is a diagram schematically showing the frequency characteristic Fn (Q) of the resonant beam 5 of the sensor body 1. Since the ratio of the resonant frequencies of the adjacent resonant beams 5 is constant, the frequency characteristics Fn (Q) expressed on the logarithmic frequency are almost the same shape and are arranged at equal intervals ΔΩ.

[0037] Assuming that the outputs of the resonant beams are added every N, the frequency characteristics of the nth output can be expressed as in equation (8).

[Equation 8]

^Η _η () = ∑ F _{n + kN} (Q)

k

= y F (Q- (n + kN) Δ Ω)

k

= F (Q-nA Ω) ^ ^δ (Ω-k A Ω) (8) k where * indicates convolution. Δ is Dirac delta function. In actual sensor body 1 (fishbone sensor), the number of resonant beams 5 is finite, but for the sake of simplicity, the sum related to k in equation (8) is treated as an infinite sum (k = _∞, ∞). Finally, the effect of the finite number of beams will be discussed.

[0038] Under the above assumption, note that the Fourier transform of the periodic δ function sequence becomes a periodic δ function sequence, and when both sides are Fourier transformed, Equation (9) is obtained.

[Equation 9] h δ (c_kAc) (9)

However, Ac can be expressed as in formula (10).

[Equation 10]

H (c) and f (c) are Fourier transforms on the logarithmic frequency axis of Η _η (Ω) and F (Q), respectively, and can be expressed as equations (11) and (12), respectively. it can.

[Equation 11]

Hn (Q) e J ^cQ dQ (11)

-OO

[Equation 12]

[0039] Note that the sensor body 1 has a logarithmic linear structure. The logarithmic frequency Ω is proportional to the longitudinal position of the transverse beam 3 (the interval between the resonant beams 5 is proportional to the difference of the logarithmic frequency Ω). So H (Ω) can be regarded as a kind of wave on transverse beam 3. Therefore, h (c) corresponds to the transformation of the wave H (Ω) into the (spatial) frequency domain.

[0040] Let f (c) be a narrow band centering on Ac and satisfy equation (13).

[Equation 13] f (c) = 0 (c≤0 or c≥2Ac) (13) At this time, the k ≠ l term of the δ function in Eq. (8) is 0, so the k = l term Only the contribution of remains, and Equation (14) is obtained.

[Equation 14] h (c) = f (c) e] ^{nA £ c} 'AcS (c— Ac)

Acf (Ac) e ^ ^{n / N} 'δ (c 1 Ac) (14) This is expressed by the following equation (15) when the inverse Fourier transform is performed.

Η _η (Ω) Acf (Ac) e ^jAcQ e ^{j27rn / N} (15)

[0041] ^Note that the term that depends on Ω is the phase rotation term e ^{iaeQ and} the term that depends on n is the phase rotation term e ^{j27rn / N.} This means that the filter is an all-pass filter that is constant regardless of phase shift of 2πn / N. Η (Ω) to Η (Ω) is a representation of the Hilbert transform pair in terms of power.

1 Ν

Karu.

[0042] As a result of the above, the structural parameter is controlled so that the Fourier transform f (c) of the frequency characteristic on the logarithmic frequency axis becomes narrow enough to satisfy the equation (13), and the amplitude peak of f (c) for c

0

c = Δο = 2π / (ΝΔ Ω)

0

It can be seen that by selecting the logarithm of the resonant frequency ratio Δ Ω so as to satisfy the above, it is possible to realize the Hilbert transform pair output by the phase addition method.

[0043] Finally, in order to consider the effect when the number of resonant beams is finite, assuming that the range of k in the periodic δ function sequence in Eq. (8) is a first power Κ, Eq. (16) Can express.

[Equation 16]

Ηη (Ω) = F (Q-nA Ω) ^ ∑ δ (Ω-kNA Ω) (16) k = -K This Fourier transform is expressed by the following equation (17).

[Equation 17] K

hf (c) Θ ^ ^{ηΔ Ωε} ">> _e jkNA Qc

n (c) ⁷

k = -K

= _f ( _c ) _e jnAQc.D _K ( _c ) (17)

[0044] However, D (c) in the equation (17) is expressed by the following equation (18) and satisfies the equation (19).

κ

Δο = 2π / (ΝΔ Ω)

Is a periodic function of

[Equation 18]

[Equation 19] oo

lim D _K (c) = Ac>: δ (c-kAc) (19)

Κ → oo k = — oo

[0045] When K is finite D (c) has a peak of height 2K + 1 at c = kAc (k is an integer). So

K

Then, there is a spread around Ac / (2K + 1) on one side around the peak. That is, AcZ (2K + l) is the peak force up to the first zero point. Therefore, in the same way as equation (13), if equation (20) holds, multiplying f (c) will cut only c = Ac in D (c).

K

Therefore, it can be understood that the same argument as above is valid.

[Equation 20] f ^{(c) =} . (^ ΤΓ or ^2Ac _ ^ TT) ⁽²⁰⁾

In the example of the vibration wave detection device of FIG. 2, N = 3, and the Hilbert transform pair output is obtained as an instantaneous value in real time in three phases every 2π / 3. From Equations (7) to (20), if the ratio of resonant frequencies of resonant beams selected every other line (本 ΔΩ) is constant, ΔΩ is not constant. I can tell you what you need to do. When ΔΩ is constant, the N-phase is equidistant on the complex plane.

[0047] Further, it is not necessary to output all N phases as the Hilbert transform output. For example, with N = 4, a Hilbert transform pair can be obtained with n = l and 2 phase outputs. If this is applied, if the logarithmic linear structure is self-similar, the resonant frequency and interval of the resonant beam are set appropriately, N = 2, and a two-phase Hilbert transform pair with a phase difference of π Ζ2. It is also possible to obtain output.

[0048] When ΔΩ is made constant, that is, the ratio of the resonant frequencies of the adjacent resonant beams is made constant, and output is made in three phases, it is easy to handle the output as soon as the sensor body 1 creates it. In that case, a component orthogonal to the first output can be obtained from the outputs of the second and third phases by appropriately adjusting the gain. In the case of four phases, the declination angle differs by π Ζ2, so the first and third phases, and the second and fourth phases become opposite phase signals, but the real part (first and third phases) Phase) and imaginary part (2nd and 4th phase) signals

[0049] As described above, according to the vibration wave detection apparatus of the present invention, it is possible to obtain a Hilbert transform pair output expressed as a single phase as an instantaneous value in real time.

[0050] The vibration wave detection method of the present invention can be used in any scene where a conventional microphone or vibration sensor is used. Furthermore, it can be used in the following cases, which could not be done in the past.

[0051] Based on the Hilbert transform output, vibration / acoustic detection with high time resolution, for example, abnormal sound can be detected instantaneously in a continuously operating machine. In addition, a wideband AM / FM demodulator can be realized. Then, noise detection can be performed using the redundant signal of the negative phase.

[0052] (Modification of Embodiment 1)

FIG. 4 shows an example of a vibration wave detection device in the case where the resonant beam 5 is provided on both sides of the transverse beam 3. In the sensor body 1 shown in FIG. 4, the resonant beams 5 on both sides of the transverse beam 3 have the same resonant frequency, and η sets of resonant beams 5 are formed in pairs facing each other.

FIG. 5 is a circuit diagram showing an example of the vibration wave detection apparatus of the present invention using the sensor body 1 of FIG. In the distortion generating part (crossing beam 3 side) of each resonance beam 5 of the sensor body 1, Ezoresistors 61a, 61b to 6ma, 6mb (hereinafter collectively referred to as piezoresistor 6) are formed. The plurality of piezoresistors 6 are connected in parallel, and one ends of the upper piezoresistors 61a to 6ma in FIG. 5 are connected to a power source 7a having a bias voltage V. Figure 5 Lower Piezo

0

One ends of the resistors 61b to 6mb are connected to a power source 7b having a bias voltage—V.

0

[0054] The other end of the piezoresistor 6 is connected to the input terminal of the operational amplifier 10 by a common line every other N_1, where N is a positive integer. In Fig. 5, N is 3, and the other end of the piezoresistor 6 is

3—1 = Every two wires are connected to a common line. That is, the piezo resistors 61a, 61b,... Are connected to the operational amplifier 10a, and the piezo resistors 62a, 62b,.

63a and 63b are connected to the operational amplifier 10c.

[0055] The + input terminal of the operational amplifier 10 is grounded. Since every other N− output line is connected to the power supply 7b via the piezoresistor 6nb of the paired resonant beam 5nb, the dummy resistor Rd is not required.

In the sensor body 1 of FIG. 5, the resonance frequencies of the paired resonance beams 5na and 5nb are the same and are added as the same phase, so the same result as the configuration of FIG. 2 is obtained. In the case of Fig. 5, the sensitivity is doubled because the upper and lower piezoresistors 6 are differential.

[Embodiment 2]

FIG. 6 is a circuit diagram showing an example of the vibration wave detection device of the present invention when the detector is a capacitor.

[0058] Electrodes 91 to 9m (hereinafter collectively referred to as electrodes 9) are formed on the semiconductor silicon substrate 20 at positions facing the front end portions 81 to 8m (hereinafter collectively referred to as front end portions 8) of the respective resonant beams 5. A capacitor is constituted by the tip 8 of each resonance beam 5 and each electrode 9 opposed thereto. The tip 8 of the resonant beam 5 is a movable electrode that moves up and down with vibration. On the other hand, the electrode 9 formed on the semiconductor silicon substrate 20 is a fixed electrode whose position does not move. When the resonant beam 5 vibrates at a specific frequency, the distance between the counter electrodes changes, so that the capacitance of the capacitor changes.

The plurality of electrodes 9 are connected in parallel and connected to a power source 7a with a bias voltage V.

0

The tip 8 of each resonant beam 5 is connected to the input terminal of the operational amplifier 10 by a common line every N_l, where N is a positive integer. Such a configuration is called an N-phase addition method. Figure In 6, N is 3, and the tip 8 is connected to a common line every 3—1 = 2. In other words, the tips 81,... Are connected to the operational amplifier 10a, the tips 82 are connected to the operational amplifier 10b, and the tips 83 are connected to the operational amplifier 10c. The + input terminal of the operational amplifier 10 is grounded. A common line connected every N_ l lines is connected to a negative voltage—V power supply 7b via a dummy resistor Rd.

0

[0060] The vibration wave detection device of FIG. 6 is completely different from that of the first embodiment except that the phase of the resistance to the vibration wave and the change of the capacitor are different from those of the sensor body 1 of the piezoresistor 6 of FIG. The same can be handled. Therefore, even if the detector is a capacitor, every H−1 every other time, the Hilbert transform pair output can be obtained as an instantaneous value in real time.

[0061] (Modification of Embodiment 2)

FIG. 7 shows an example of a vibration wave detection device in which the resonance beam 5 is provided on both sides of the transverse beam 3 and the detector is a capacitor.

[0062] Similar to the modification to the first embodiment (Fig. 5), the resonance beams 5 on both sides of the transverse beam 3 have the same resonance frequency, and m pairs of resonance beams 5 are formed in pairs. ing. Electrodes 91a, 91b-9ma, and 9mb (hereinafter referred to as electrodes 9) are disposed on the semiconductor silicon substrate 20 at positions facing the distal ends 81a, 81b to 8ma, and 8mb (hereinafter collectively referred to as distal ends 8) of the resonance beams 5, respectively. And a capacitor is constituted by the tip 8 of each resonance beam 5 and each electrode 9 opposed thereto.

[0063] The upper electrodes 91a to 9ma in Fig. 7 are connected to a power source 7a having a bias voltage V. Fig 7

0

The lower electrodes 91b to 9mb are connected to a power supply 7b having a noisy voltage −V.

0

The tip 8 of each resonant beam 5 is connected to the input terminal of the operational amplifier 10 by a common line every other N—where N is a positive integer. In Fig. 7, N is 3 and the tip 8 is connected to a common line every 3 – 1 = 2. In other words, the tips 81a, 81b, ... are connected to the operational amplifier 10a, the tips 82a, 82b, ... are connected to the operational amplifier 10b, and the tips 83a, 83b, ... are connected to the operational amplifier 10c. ing. The + input terminal of the operational amplifier 10 is grounded

[0064] The vibration wave detecting device of FIG. 7 is a modification of the first embodiment except that the phase of the resistance change and the change of the capacitor with respect to the vibration wave is different from that of the sensor body 1 of the piezoresistor 6 of FIG. Example Can be handled exactly the same. Therefore, even if the detector is a capacitor, the output from the Hilbert transform can be obtained by adding every N−1. Further, compared with the configuration of the resonant beam 5 on one side in FIG.

As described above, according to the vibration wave detection apparatus of the present invention, it is possible to obtain the Hilbert transform pair output as an instantaneous value in real time even when the detector is a capacitor.

[0066] Note that in the example of the vibration wave detection device of Figs. 6 and 7, N = 3, and a Hilbert transform pair output is obtained in three phases every 2π / 3. Ν_ If the resonance frequency ratio (の Δ Ω) of every other selected resonant beam is constant, Δ Ω may not be constant. When ΔΩ is constant, the phase of the phase is equidistant on the complex plane. In addition, it is the same as in the first embodiment that all the phases are not output.

[0067] The hardware configuration described above is merely an example, and can be arbitrarily changed and modified.

[0068] This application is based on Japanese Patent Application No. 2006-177199 filed on June 27, 2006. In this specification, the specification, claims and entire drawings of Japanese Patent Application No. 2006-177199 are incorporated by reference.

Industrial applicability

The present invention can be used for a frequency detection device that detects the frequency of sound waves.

Claims

The scope of the claims

[1] A vibration wave detection method for detecting a vibration of each of the resonators by propagating a vibration wave to a plurality of resonators (5:! To 5 m) resonating at different specific frequencies,

A method for detecting a vibration wave, wherein N is an integer of 2 or more, and a plurality of signals are output by selecting the plurality of resonators every N_1 and adding the outputs of the detectors.

[2] The plurality of resonators are arranged by setting a resonance frequency of the resonators so that a ratio of resonance frequencies of the N-1 every other resonator of the plurality of resonators is constant. The vibration wave detection method according to claim 1, wherein:

3. The vibration wave detection method according to claim 1, wherein the N is an integer of 3 or more.

[4] A series of resonators (51 to 5m) resonating at specific frequencies different from each other so that the position of each resonator is logarithmic linearly proportional to the logarithm of the resonance frequency ( 51-5m)

A detector (61 to 6 m) for detecting the vibration of each of the plurality of resonators by the vibration wave propagated to the resonator array;

A plurality of output synthesizers (10a to 10c) that select the plurality of resonators every N_ 1 and add the outputs of the detectors, where N is an integer greater than or equal to 2,

A vibration wave detection device comprising:

[5] The resonator array may be arranged by setting a resonance frequency of the resonators so that a ratio of resonance frequencies of every other N− resonators of the plurality of resonators is constant. The vibration wave detection device according to claim 4, which is a feature.

6. The vibration wave detection device according to claim 4, wherein the N is an integer of 3 or more.

7. The vibration wave detecting device according to claim 4, wherein the detector is a piezoresistor (61 to 6 m).

8. The vibration wave detecting device according to claim 4, wherein the detector is a capacitive element (81 to 8 m, 91 to 9 m).