JPH1024038A - Ultrasonograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an acoustic structure from the surface to the depth of a subject for inspection by providing a separating and detecting means by which, of ultrasonic response signals output from a pulse generating/receiving means, only the ultrasonic response signal that was the first to act on the subject for inspection is separated and detected immediately after the application of a pulse signal. SOLUTION: A trapezoidal pulse signal 16 controlled by a control signal 28 from a trapezoidal pulse waveform control part 15 is made to branch into two by a branch circuit, and one branch signal 17a is applied to an ultrasonic transducer 4 via an amplifier 3. Ultrasonic vibration produced thereby is made to comes into an object, and an echo signal reflected by its boundary surface with foreign matter is input to a differential amplifier 6 via an attentutor 5. A delay circuit 7 is made to match the other lower branch signal 17b, and the signal is output as a signal 23 from which an applied voltage signal is eliminated. Thus by separating and detecting an ultrasonic response signal immediately after application to the ultrasonic transducer 4, the surface state of the object can be diagnosed with accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transducer for analyzing an ultrasonic response signal generated by applying a pulse voltage to an ultrasonic transducer and detecting an acoustic structure over a surface and a deep portion of a test object. The present invention relates to an ultrasonic diagnostic apparatus.

[0002]

2. Description of the Related Art Generally, an ultrasonic diagnostic apparatus which analyzes an ultrasonic response signal generated by applying a pulse voltage to an ultrasonic transducer to detect an acoustic structure of an object to be inspected is used in the medical field and non-medical fields. Practical in the field of destructive inspection.

[0003] Various structures and driving methods have been developed for these ultrasonic transducers. For example, in the medical field, the demand for an ultrasonic endoscope capable of diagnosing an abnormality of a living tissue without interfering with subcutaneous fat or ribs by inserting an ultrasonic transducer into a body cavity is rapidly increasing.
Further, there has been proposed an ultrasonic diagnostic apparatus which inserts an ultrasonic transducer catheter into a blood vessel and diagnoses the presence or absence of a thrombus deposited in the blood vessel and the hardening of the blood vessel. On the other hand, an ultrasonic diagnostic apparatus for diagnosing the viscoelastic property of the surface of a living tissue is also called a tactile sensor apparatus, and research and development are proceeding.

For example, US Pat. No. 5,454,373 discloses an ultrasonic transducer catheter. This ultrasonic transducer catheter
13 (a) and 13 (b), that is, a transducer assembly 103 rotatably disposed at the tip of a flexible tubular structure 101 via a bearing 102 is rotated by rotation of a rotation drive shaft 104. By doing so, the ultrasonic beam is mechanically scanned to obtain an ultrasonic tomographic image.

The ultrasonic transducer 105 used in this device has a structure as shown in FIG.
An ultrasonic transmission lens 108 is bonded to the surface on the ultrasonic transmission / reception side of the piezoelectric element 107 of 2 mmφ, and a backing material 109 is bonded to the back side. With such a structure, it is possible to draw the shape of the thrombus 112 attached to the blood vessel wall 111 near the bifurcation 100 of the blood vessel, and the ultrasonic wave is detected based on the detection time of the ultrasonic echo signal and the amplitude of the ultrasonic echo signal. This is for combining images.

On the other hand, the applicant of the present invention is disclosed in
No. 73396 proposes a tactile sensor for detecting the viscoelasticity of blood vessels. This tactile sensor is an ultrasonic vibrator as shown in FIG. 14 (piezoelectric body 107a shown in FIG. 15).
It extracts the parameters of the vibration response when an impulse voltage is applied to the object, processes these parameters, and uses the calculated result to provide a tactile sensation corresponding to both the viscoelasticity of the surface and the deep part of the object This is a tactile sensor device capable of deep diagnosis. Here, tactile sensing is to detect the hardness of the surface of an object, and therefore, this tactile sensor is proposed to detect an acoustic structure over the surface and a deep portion of the object. It can be restated as an ultrasound diagnostic device.

[0007]

As described above, Japanese Unexamined Patent Publication No. 6-273396 proposes an ultrasonic diagnostic apparatus for detecting an acoustic structure over a surface and a deep portion of a test object. By improving the following problems, a more preferable ultrasonic diagnostic apparatus can be provided.

First, when detecting information on an acoustic structure over a surface and a deep portion from a vibration response waveform when an impulse voltage is applied, surface information, that is, tactile information, is an ultrasonic response signal immediately after the impulse voltage is applied. , And the deep information is included in an ultrasonic response signal, that is, an echo signal following the immediately following ultrasonic response signal.

[0009] These ultrasonic response signals are converted into high frequency pulse signals by the piezoelectric effect of the piezoelectric vibrator, and an impulse voltage signal is superimposed on the high frequency pulse signal converted from the immediately succeeding ultrasonic response signal. Since it is observed, it is difficult to detect a change in the ultrasonic response signal immediately after contact with the object from the superimposed signal. That is, surface information,
That is, it is difficult to detect tactile information with high sensitivity.

Therefore, there is a need to separate and detect a high-frequency pulse signal corresponding only to an ultrasonic response signal immediately after the application of an impulse voltage from a high-frequency pulse signal on which an impulse voltage signal is superimposed, and to analyze the high-frequency pulse signal. Becomes
Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of detecting an acoustic structure over a surface and a deep part of a test object.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an ultrasonic diagnostic apparatus for detecting an acoustic structure of an object using ultrasonic waves. An ultrasonic transducer composed of a piezoelectric vibrator, generating a predetermined pulse signal, applying the pulse signal to the ultrasonic transducer, generating an ultrasonic wave, irradiating the object, and reflecting the ultrasonic wave. Pulse generating / receiving means for receiving the generated ultrasonic wave and outputting it as an ultrasonic response signal, and the pulse which has acted on the object first among the ultrasonic response signals output from the pulse generating / receiving means Provided is an ultrasonic diagnostic apparatus having separation detecting means for separating and detecting only an ultrasonic response signal immediately after a signal is applied.

[0012] Further, the separation detecting means may be a branching means for branching the pulse signal generated by the pulse generating / receiving means into at least two equivalent signals, and amplify one of the branch signals branched by the branching means. Amplifying means, and a signal responding immediately after applying the amplified signal from the amplifying means to the ultrasonic transducer is input as the immediately following ultrasonic response signal, and the amplitude of the immediately following ultrasonic response signal is a predetermined value. And a delay means for delaying the other branch signal branched by the branching means, and a difference means for calculating a difference between a delay output from the delay means and an attenuation output from the attenuation means. . Or
The separation detecting means has a low-loss ultrasonic delay medium and a gate means for separating and detecting only the immediately following ultrasonic response signal.

In the ultrasonic diagnostic apparatus having the above-described configuration, when a predetermined pulse voltage is applied to the ultrasonic transducer from the pulse generator of the pulse generating / receiving means, the ultrasonic transducer causes a specific resonance of the piezoelectric vibrator. An object is irradiated with an ultrasonic signal having a frequency component equal to the frequency, an ultrasonic response signal is generated from the reflected ultrasonic signal, and the generated signal is converted into a high-frequency pulse voltage signal by a piezoelectric effect of a piezoelectric vibrator. Is converted. Among these voltage signals, the voltage signal generated immediately after the application of the pulse voltage includes the applied pulse voltage signal and the high-frequency pulse voltage signal obtained by piezoelectrically converting the immediately following ultrasonic response signal. Contains a tactile signal corresponding to the surface state of the object.

Therefore, only the ultrasonic response signal immediately after the application of the pulse voltage is separated and detected by the separation detecting means,
A predetermined analysis process is performed to detect the acoustic structure, and the surface condition of the object is diagnosed.

The immediately following ultrasonic response signal includes a tactile signal corresponding to the surface condition of the object, and has means for separating, detecting, and analyzing the ultrasonic response signal immediately after application of the pulse voltage. If so, the effect of diagnosing the surface condition of the object can be obtained.

Further, the ultrasonic wave generated in the piezoelectric vibrator is applied to an object through a low-loss ultrasonic delay medium, and a response signal at this time is returned to the piezoelectric vibrator through the low-loss ultrasonic delay medium, and the piezoelectric vibrator is driven. The signal is converted into a high-frequency pulse voltage signal by the piezoelectric effect of the element. Since the high-frequency pulse voltage signal in this case is delayed from the pulse voltage application timing by the time that the ultrasonic wave generated in the piezoelectric vibrator reciprocates in the low-loss ultrasonic delay medium, the gate means for transmitting only the signal after the lapse of this time Through. The signal passing through the gate means does not include the voltage waveform applied to the piezoelectric vibrator.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. A first embodiment of an ultrasonic diagnostic apparatus according to the present invention will be described with reference to FIGS. Here, FIG. 1 is a diagram showing a configuration example of the ultrasonic diagnostic apparatus according to the first embodiment, FIG. 2 is a diagram schematically showing an ultrasonic response waveform, and FIG. 3 is an internal view of a trapezoidal pulse generator. FIG. 4 is a diagram showing a configuration example, FIG. 4 is a diagram for explaining the principle of dynamic damping, and FIG. 5 is a diagram for explaining the present embodiment, which is a method used in a normal ultrasonic diagnostic apparatus. It is a figure showing the obtained ultrasonic response waveform.

[0018] In the ultrasonic diagnostic apparatus, for example, the maximum voltage is 10V or less, the rise time t _r is 20ns or less, the variable voltage holding time t _w in 20～100Ns, the fall time t _f can be varied by 20~200ns Trapezoidal pulse generator 1 that repeatedly generates trapezoidal pulses at a constant cycle
A branch circuit 2 for branching the output signal 16 of the trapezoidal pulse generator 1 into two and generating two equivalent signals 17a and 17b, and a high-frequency amplifier for amplifying the signal 17a to 50 to 100V 3, the ultrasonic transducer 4 to which the amplified signal 18 amplified by the high frequency amplifier 3 is directly applied, and the voltage of the high frequency pulse voltage signal 19a among the high frequency pulse voltage signals 19a and 19b, which will be described later, output from the ultrasonic transducer 4. Attenuator 5 that attenuates the signal 17b to a low voltage, a gate circuit 59 that removes a response signal immediately after the pulse voltage signal 19b, a delay circuit 7 that delays the signal 17b, and a signal 21 from the delay circuit 7 and attenuation. A differential amplifier 6 for obtaining a difference from the signal 20 from the amplifier 5 and a combined output signal of the differential amplifier 6 and an output signal of the high-frequency amplifier 8 for waveform analysis. The FFT circuit 9 to the differential amplifier 6
Output signal 23 from the gate timing setting unit 1
A gate circuit 11 that allows a certain period of time to pass based on the signal from 0, and a signal 2 that passes through the gate circuit 11
5, a maximum value detector 12 for detecting the maximum value of 5 and automatically inputting its output signal 26 as an n value related to the fall time of the trapezoidal pulse to the trapezoidal pulse waveform control unit 15 at the next stage;
A plurality of n values related to the fall time of the trapezoidal pulse are stored in advance, and the manual setting circuit 13 used for optimizing the trapezoidal waveform, and the signal 26 of the maximum value detector 12 and the n value from the manual setting circuit 13 are used. It comprises a changeover switch 14 for selecting one of them, and a trapezoidal pulse waveform control unit 15 for controlling the trapezoidal pulse generator 1 based on a signal from the changeover switch 14.

The high frequency pulse voltage signals 19a, 19b
Is a superimposed signal of the applied voltage signal 18 and the high-frequency pulse voltage signal obtained by piezoelectrically converting the ultrasonic response signal. In particular, immediately after the applied voltage signal 18 is applied, the high-frequency pulse voltage signal is immediately Immediately after being obtained by the piezoelectric conversion of the ultrasonic response signal, it is a superimposed signal of the high-frequency pulse voltage signal (waveform 29 shown in FIG. 2) and the applied voltage signal 18 (same as the waveform 30 shown in FIG. 2), which is considerably complicated. Waveform (not shown). In FIG. 1, a portion surrounded by a dotted line of the attenuator 5, the differential amplifier 6, and the delay circuit 7 indicates a circuit block unit for separating the immediately following ultrasonic response from the applied voltage signal 18.

Next, FIG. 3 shows an example of a specific circuit configuration of the trapezoidal pulse generator 1 and will be described. This circuit is a specific example of a circuit for realizing dynamic damping described later, and has a circuit configuration not used in a conventional ultrasonic diagnostic apparatus.

In the trapezoidal pulse generator 1, the output of the rectangular wave generator 37 is connected to an emitter follower circuit comprising a transistor 38 and an emitter resistor 46, and the output thereof is a trapezoidal pulse comprising a diode 39 and a resistor 40. , And a trapezoidal pulse fall time setting unit 36 composed of a diode 41, a resistor 42, and an FET 43.

Further, their outputs are
And an emitter follower circuit consisting of
The other is connected via a grounded integrating capacitor 44 and led to the trapezoidal pulse generator output. The gate of the FET is connected so that a control signal 28 from the trapezoidal pulse waveform control circuit 15 is input. The control signal 28 is converted into a duty setting signal 48 by the signal from the m-value setting unit 10 which determines the pulse width of the trapezoidal pulse in the trapezoidal pulse waveform control unit 15 and then input to the duty setting unit 49. The generated square wave duty ratio setting signal is output to the square wave generator 3.
7

The operation of the thus configured ultrasonic diagnostic apparatus of the first embodiment will be described. In this embodiment,
It has the following features. As a first feature, an ultrasonic response signal immediately after applying a trapezoidal pulse to an ultrasonic transducer is separated and detected. The second feature is that the immediately following ultrasonic response signal has an area where no mechanical damping is performed, and is an ultrasonic pulse having a short pulse width. As a third feature, the immediately following ultrasonic response signal is incident on the object, the signal reflected at the interface with the abnormal tissue in the object and returned to the ultrasonic transducer as an echo signal is also received, and the immediately following signal is received. And the echo signal or the relationship between the echo signals can be analyzed through FFT.

According to the present embodiment, as a method for realizing the first feature, the immediately following ultrasonic response signal is separated by electrical signal processing. Hereinafter, the operation will be described in detail with reference to FIGS.

Firstly, the control signal 28 from the trapezoidal pulse waveform controller 15, the pulse width t _w and fall time t _f
The trapezoidal pulse signal 16, which is optimally controlled, is branched by the branch circuit 2 into two equivalent branch signals 17 a and 17 b. Of these branch signals, the branch signal 17a
Is amplified by the high frequency amplifier 3 to 50 to 100 V, and the amplified signal 18 is applied to the ultrasonic transducer 4. As shown in FIGS. 6 (a) and 6 (b), the ultrasonic transducer 4 composed of a piezoelectric vibrator has no back-side load material, so that ultrasonic vibration occurs near the resonance frequency of the piezoelectric vibrator. .

This ultrasonic vibration is generated immediately after the trapezoidal pulse voltage is applied. The ultrasonic response signal 29 and the applied voltage signal 3
The superimposed signal having a large amplitude of 0 and the ultrasonic signals 31, 32, 33, and 34 that enter the object, are attenuated, reflected at the interface with the foreign matter, and observed as echo signals are shown on the time axis. Signals 19a and 19b combined with This signal 19
a is input to one input terminal of the differential amplifier 6 as an attenuated signal 20 attenuated by the attenuator 5 to a voltage of the same level as the signal 17a.

On the other hand, another output signal 1 in the branch circuit 2
7b is input to the other input terminal of the differential amplifier 6 through a delay circuit 7 in order to correct a phase delay caused by the high frequency amplifier 3 and the attenuator 5. The differential amplifier 6 outputs the signal 23 from which the applied voltage signal has been removed.

As for the signal 19b, only the echo signal from which the immediately following response signal has been removed by the gate circuit 59 is detected.
The echo signal and the signal 22 are multiplexed so as to become the same time domain signal, and become a multiplexed signal 24.
The signal is analyzed by the circuit 9. In the first operation, the ultrasonic transducer 4 is in a no-load state, and no echo signal is detected, and only the immediate response signal 22 is detected. The n value is set so that the immediate ultrasonic response waveform has an optimal shape. Set manually. At the same time, the result of the FFT analysis in that state, that is, parameters such as the center frequency f ₀ , the maximum amplitude A ₀ , and the fractional bandwidth α _{0 of the} immediately following ultrasonic response signal are stored.

Next, an object load is applied. When the object is a viscoelastic body, the inductance L and the DC resistance R are equivalently
It is known that this is inserted in series with a series resonance circuit of an equivalent circuit of the piezoelectric vibrator, so that the resonance resistance increases and the resonance frequency decreases. This is the maximum amplitude A ₀ of the immediately following ultrasonic response signal.
Means that the center frequency f ₀ decreases, and conversely, from the state of this change, it is possible to detect how much the viscoelastic body load is applied.

As for the detection sensitivity, it is preferable that the maximum amplitude A ₀ in the no-load state is not damped at all. Dynamic damping (DD) to achieve this
A method referred to as “a method” is used.

This DD method is generally used for braking mechanical vibrations by applying other mechanical vibrations. However, a conventional back load member is formed on an ultrasonic transducer to provide mechanical and mechanical vibrations. In contrast to the method used in a normal ultrasonic diagnostic apparatus of damping statically and structurally, in the present embodiment, electrically, only a wave having a certain wave number or more is dynamically damped by a driving waveform. In that sense, it is called dynamic damping. Importantly, the dynamic damping region (DD region) 57 shown in FIG. 4 is greatly damped, and as a result, the pulse width of the entire pulse is shortened, but is completely damped in the immediately preceding non-damping region 56. Not maximum amplitude
Since it has ampC, it is possible to realize surface information sensing (tactile sensing) with high sensitivity using the immediately following ultrasonic response signal. An ultrasonic response waveform obtained by a method used in a general ultrasonic diagnostic apparatus of mechanically, statically, and structurally damping by forming a back load material into an ultrasonic transducer is a signal 59a shown in FIG. The pulse width is shortened by damping like
At the same time, the entire ultrasonic pulse is damped and the maximum amplitude is already greatly damped, so that it is not possible to cause a highly sensitive change in the maximum amplitude and the center frequency.

Here, the principle of the DD method will be described with reference to FIG.
This will be described in detail below. When the step-up voltage 50 is applied to the piezoelectric vibrator on which the back load material is not formed,
From the step-up time T1, the ultrasonic vibration 51 having the maximum amplitude ampA is excited. Step-down voltage 52
Is applied, the maximum amplitude a starts from the step-down time T2.
Ultrasonic vibration 53 having mpB and inverted in phase is excited. This is the frequency component of the sudden change of in the applied voltage at time T2 is assumed that at least the resonance frequency of the piezoelectric vibrator, whereby occurs a piezoelectric resonator, by falling gently falling (time t _f) Due to the damping, the maximum amplitude attenuates to amp B.

[0033] When applying the above two stepwise applied voltage trapezoidal pulse 54 having the synthesized voltage holding time t _w a, it can be seen that the ultrasonic pulse 55 having a non-damping region 56 and the damping region 57 can be obtained .

[0034] To obtain the short ultrasound pulses pulse width having such a non-damping region, the rise time of the trapezoidal pulses t _r, a voltage holding time t _w, the fall time t _f, the piezoelectric vibrator When the reciprocal of the resonance frequency and _{t p, t r <t p} <t f t w = n × t p (n = 1~5) t f = m × t p (m = 1~10) are preferred conditions It is. If n> 5, the pulse width becomes too long, and the resolution in the depth direction decreases. But,
When m> 10, the frequency component of the sudden change portion of the applied voltage at time T2 does not exceed the resonance frequency of the piezoelectric vibrator, and the DD effect is greatly reduced.

Next, the operation of a trapezoidal pulse signal generator for generating an optimal trapezoidal pulse signal will be described in detail with reference to FIG. By a control signal from the duty setting device 49, the pulse width t _w, repetition frequency 1k~1
A rectangular wave of 0 kHz is generated from a rectangular wave generator 37.
And t _r setting unit consisting of a series connection of a forward diode 39 and the resistor 40 via an emitter follower circuit comprising the generation signal from the transistor 38 and emitter resistor 46, the reverse direction of the diode 41 and the resistor 42 and the variable resistor FET4
3 is connected to the parallel connection branch of the t _f setting unit 36 composed of series connection.

The rise time _tr is determined by the resistor 40 and the capacitor 44. The fall time t _f is determined by the resistance 42, the resistance between the source and the drain of the FET 43, and the capacitor 44. The source-drain resistance is
Control is performed by the gate voltage signal 28 (control signal 28) of the FET 43. The gate voltage signal 28 is converted from the signal 27 by the trapezoidal pulse waveform control circuit 15 and the m-value setting circuit. The signal 27 is a feedback signal for minimizing the maximum voltage in the DD region. The signal 27 is used manually from the n-value setting circuit 13 or directly uses the output 26 of the maximum value detection circuit 12.

Next, the detection of the information in the deep part, that is, the detection of the internal viscoelastic characteristic of the object by the detection of the echo signal will be described with reference to FIG. The branch signal 19b of the ultrasonic response signal of the piezoelectric vibrator of the ultrasonic transducer 4 is controlled to pass only the echo signal having a small amplitude through the gate circuit 59, and is input to the high frequency amplifier 8 and amplified. The output signal is synthesized with the immediately following ultrasonic response signal 22, and the synthesized signal 2
After that, the signal is analyzed by the FFT circuit 9.

As shown in FIG. 2, the composite signal 24 is composed of an immediately following ultrasonic response signal 29, an echo signal 31 (reflection on the surface of a foreign material), a signal 32 (reflection on the back surface of a foreign material), and a signal 33 (reflection on the surface of the foreign material and the surface of the object). (Multiple reflections between objects) and the signal 34 (backside reflection of the object), the sound speed of the object from time t ₁ , the sound speed of foreign matter in the object from time t ₂ , Amplitude ratio A ₁ / of sound wave response signal 29 and echo signal 31
From the relationship of A ₀ , the attenuation rate α ₁ of the object is equal to the echo signal 31.
And the amplitude ratio A ₂ / A ₁ of the echo signal 32, the attenuation rate α _{2 of the} foreign substance existing in the object is calculated based on the following equations.

Sound velocity V ₁ = 2d ₁ / t ₁ , V ₂ = 2d ₂ / t ₂ attenuation α ₁ = 20 log (A ₁ / A ₀ ) / d ₁ α ₂ = 20 log (A ₂ / A ₁ ) / d ₂ However, in the above equation, if the distance d ₁ from the surface to the foreign matter and the layer thickness d _{2 of} the foreign matter are known, both the sound velocity and the attenuation rate can be expressed by absolute values, but in the case of an object such as actual biological tissue, Does not know d ₁ and d ₂ from the beginning. However, the acoustic velocity V ₂ of the foreign matter can be inside the object, so can be approximated as close to V _1, the dimensional ratio d ₁ / d ₂ would be approximated by t ₁ / t _2.

Accordingly, since the damping ratio corresponds to the viscosity ratio, the relative viscosity ratio of the foreign matter inside the object can be determined. Normally, the sound speed of a living body is 1570 m / s for a liver having a relatively fast sound speed, and 1476 m for a fat having a relatively slow sound speed.
m / s, and the difference is 6.5%. Even if the sound speed V ₁ of the object is approximated to be equal to the sound speed V ₂ of the foreign matter, the dimensional error due to this approximation is also 6.5%. There is no problem in actual diagnosis, and there is no problem in ordinary ultrasonic diagnosis.

Note that the sound velocity and the attenuation can be determined by any of the following methods based on FFT analysis. The ultrasonic response signals 29, 31, 32, 3 shown in FIG.
Each FFT of _{3,34 F 0, F 1, F} 2, F
_3, and F _4, the frequency f. Assuming that the phase difference between F ₀ and F ₁ is φ ₁₀ and the phase difference between F ₁ and F ₂ is φ ₂₁ , V ₁ = 4πd ₁ / (φ ₁₀ / f) and V ₂ = 4πd ₂ / (φ
₂₁ / f) Attenuation α ₁ = 20 log (| F ₁ / F ₀ |) / 2 d ₁ α ₂ = 20 log (| F ₂ / F ₁ |) / 2 d ₂ Subsequent processing is the same as the above-described method, and a description thereof will be omitted.

Next, FIG. 6 shows and describes the configuration of an ultrasonic transducer used in the ultrasonic diagnostic apparatus of the present invention. The piezoelectric vibrator 4 of the ultrasonic transducer 4
a has a lead electrode 60ac folded back from the partial electrode 60a to the back surface, and the partial electrode 60b also has a lead electrode 60ac.
with bc. The holding portion 61 includes a conducting wire 67 insulated from each other.
68, each having an electrode pad 61a, 61b,
61c and 61d are connected to the holding portion 61 shown in the drawing.

Further, in order to be detachable from the tubular structure 77, a female screw portion (not shown) of the tubular structure 77 as shown in FIG. .
The extraction electrode 61ac is connected to the holding electrode pad 61a by 61bc.
Is bonded to the electrode pad 61b to integrate the piezoelectric vibrator 59 and the holding portion.

As an example of the bonding method at this time, a conductive paste is applied to the electrode pads 61a and 61b, an anaerobic adhesive is applied around the conductive paste, and the position of the piezoelectric vibrator 4a is confirmed on the holding portion 61. Then, after pressurizing for a certain time, washing is performed.

By using the anaerobic adhesive, the adhesive at the site that has been in contact with the air does not cure and can be easily removed. Then, a pressure receiving part is applied. When a material serving as an adhesive such as an epoxy resin is used as the pressure receiving portion material, the pressure receiving portion application, the bonding of the piezoelectric vibrator and the holding portion, and the pressure receiving portion formation are performed without performing the above-described process. It is possible to do with.

The assembled holding portion 61 is screwed into the tubular structure 77. The tubular structure 77 has an O-ring 69, a spring portion 66a serving as an electric terminal connected to a signal line in the tubular structure 77, 66b. The ring 69 ensures airtightness, and the spring portion ensures conduction with the holding portion. Here, the two spring parts are upper electrodes 60a,
The spring portions 66 correspond to the lower electrodes 60b, respectively.
A change in the impedance characteristic of the piezoelectric vibrator 4a is transmitted as information to the signal line connected to the a and 66b.

Since there is a possibility that the material of the holding portion is in direct contact with the living body, high-density polyethylene is desirable in consideration of biocompatibility and adhesion to the piezoelectric vibrator. However, if priority is given to biocompatibility, Teflon or polyurethane may be used. Further, when the attachment / detachment is not considered, the screw portion 62 may be omitted and the attachment may be simply performed.

FIG. 7 shows a modified example of the holding portion 61. In the rivet shape of the holding portion, the electrode terminals 61c and 61d that are electrically connected to the respective electrodes of the piezoelectric vibrator 4a are exposed in the recesses of the rivet. On the other hand, the tubular structure 77 shown in FIG. 8 is provided with a female part (not shown) of a rivet, and the ends thereof are provided with terminals 66ta and 66tb which are electrically connected to the signal lines.

When the holding portion 61 and the tubular structure 77 are fitted, the respective terminals come into contact and become electrically conductive. After the conduction is confirmed, the holding portion and the tubular structure 77 are bonded using an adhesive (epoxy). Adhesively fixed.

When the pressure receiving portion 63 is not in contact with the object 65, there is a large difference in the acoustic impedance between the acoustic coupling layer and pressure receiving portion 63 and air, so that ultrasonic waves are hardly emitted on any surface. It does not radiate and freely vibrates at the resonance frequency of the ultrasonic vibrator composed of the piezoelectric vibrator 4a and the acoustic coupling layer and pressure receiving portion 63.

In this free vibration, since no back load material is formed on the back side, that is, on the electrode 60b side, free vibration with a large amplitude can be realized. Another reason for realizing such a large amplitude free vibration is that the electrodes 60a, 60b
Is used as a partial electrode, and mounted on the mounting structure 61.
Vibration does not occur at the edge of the piezoelectric vibrator.

When the object 65 comes into contact with the free vibration having such a large amplitude, the resonance frequency and the resonance resistance of the large amplitude free vibration change according to the load state of the object. In response to this, the center frequency of the ultrasonic vibration,
Since the vibration amplitude also changes, the mechanical characteristics of the object 65, for example, the viscoelastic characteristics, can be grasped by detecting the amount of change. As described above, according to the present embodiment, the response signal immediately after the ultrasonic wave immediately after the application of the trapezoidal pulse can be separated and detected, and the echo signal can also be detected. The response signal immediately after the ultrasonic wave can be obtained by using a characteristic technique called dynamic damping, and the response signal immediately after the ultrasonic wave having a short pulse width which is hardly damped.

Since this signal is hardly damped, its center frequency and amplitude are changed with high sensitivity depending on the object load. This means that the detection of the surface information (viscoelasticity of the surface) of the object can be performed with high sensitivity. If the viscoelastic object is considered to be a living tissue, it is possible to perform a highly accurate biological tissue diagnosis. Means to connect to

On the other hand, the echo signal obtained by the response signal immediately after the ultrasonic wave having a short pulse width penetrates the object also changes the amplitude and center frequency according to the viscoelastic characteristics of the propagation path. By analyzing the relationship between the response signal immediately after the sound wave and the echo signal and the relationship between the echo signals, for example, changes in amplitude and center frequency, it is possible to detect deep information (viscoelasticity in the depth direction) of the object with high sensitivity. This means that if the viscoelastic object is considered to be a living tissue, it will lead to a favorable effect that a deep diagnosis of the living tissue can be performed with high accuracy.

As described above, the present embodiment can provide an ultrasonic diagnostic apparatus capable of detecting surface information that was impossible with a conventional ultrasonic diagnostic apparatus. On the other hand, since the detection of the surface information can be regarded as tactile sensing, it is possible to provide a tactile sensor device capable of detecting deep information, which was impossible with a conventional tactile sensor device.

Next, FIGS. 8A to 8D show, as a second embodiment, the configuration of an ultrasonic transducer used in the ultrasonic diagnostic apparatus of the present invention, and will be described. FIG. 8 (a)
FIG. 3B shows the appearance of an ultrasonic transducer catheter 77 provided with an acoustic coupling layer and pressure receiving portion 78 at the distal end, and FIG.
2 shows a cross section near the front end when viewed from the direction A.

This ultrasonic transducer catheter 7
7 is a two-body structure as shown in FIG.
As shown in FIG. One of the two-body structure has a structure in which a plurality of piezoelectric vibrators 82a to 82h are joined to a plurality of portions of the holding structure 80 provided with the fitting portion 80a and the fitting stopper 83.

First, a cylindrical material made of fused quartz or the like is cut or ground to form a fitting portion 80a, and the surfaces 89a to 89h to which the piezoelectric vibrators 82a to 82h are mounted.
89h are formed.

Next, as the common ground electrode 99, gold, platinum, or gold is used by using means such as sputtering or vacuum deposition.
/ Titanium, Platinum / Dish-shaped surface including piezoelectric oscillator bonding surfaces 89a to 89h and fitting portion 80a
It is formed so as to be continuous on the surface of. Further, the piezoelectric vibrator 82 is bonded to the piezoelectric vibrator joining surfaces 89a to 89h by bonding or the like.
a to 82h are joined. Then, the piezoelectric vibrators 82a to 82a
A pressure receiving portion 78 is formed by coating a thin layer of silicone resin or urethane resin on 2 h.

The stopper ring 83 is fixed to the cylindrical fitting portion 80a with an adhesive, and the ultrasonic transducer head 92 is completed. This ultrasonic transducer head 9
FIG. 8D is a view of No. 2 from the direction B in FIG. 8C.

From these piezoelectric vibrators 82a to 82h, lead wires 93a to 93h are led to the central shaft tubular hole 98, and are connected to terminals 93a "to 93h" via internal wirings 93a "to 93h".

On the other hand, the central shaft tubular hole 98 of the tubular structure 79
The metal film 94 is formed on the inner wall of the piezoelectric vibrator 82.
A coaxial multi-core cable 96 for transmitting and receiving an electric signal is arranged for each of a to 82h. This coaxial multi-core cable 9
The shield wire (not shown) of No. 6 is connected to the metal film 94 formed on the inner wall of the central shaft tubular hole 98 ′ in the vicinity of the hand operation portion of the tubular structure 79.

The front end of the ultrasonic transducer head 92 finally seals and seals the front blocking member 97. The operation of the ultrasonic transducer head thus configured will be described. A trapezoidal pulse voltage is applied to the piezoelectric vibrator 82 through the coaxial multi-core cable 96 and the ground electrodes 94 and 99.
a to 82h. By this application, the ultrasonic pulses generated in the piezoelectric vibrators 82a to 82h act on the object, undergo modulation in accordance with the viscoelastic characteristics of the object, and are observed immediately after as an ultrasonic response signal. This transmission / reception is sequentially performed for each of the piezoelectric vibrators 82a to 82h using means such as an electronic changeover switch.

Since the piezoelectric vibrator in which no echo signal is observed is not in contact with the object, if the position of the piezoelectric vibrator is known, the direction of the ultrasonic transducer head 92 can be known. Also, a response signal from the piezoelectric vibrator not in contact with the object is subjected to FFT analysis to extract parameters such as a center frequency f ₀ , a maximum value A ₀ , and a fractional bandwidth,
The viscoelastic characteristics of the object can be determined by comparing these values with the center frequency f ₀ , the maximum value A ₀ , and the specific bandwidth α of the reflected ultrasonic wave 29 from the object contact surface. The signal processing method of each of the plurality of ultrasonic transducers is the same as in the first embodiment described above, and the description is omitted here.

When the piezoelectric vibrator comes into contact with the object and an echo signal can be detected from each object, an annular scanning tomographic image is obtained by performing electronic scanning sequentially. The signal processing method in this case is exactly the same as that in the case of the linear electronic scan ultrasonic diagnostic apparatus, and the description is omitted here.

Such an annular scanning tomographic image is effective for diagnosing a 360-degree surrounding state of a lumen wall such as a blood vessel.
As described above, when in contact with the object, the ultrasonic response signal reflected on the object surface is analyzed, the viscoelastic characteristics of the object are evaluated, and tomographic information can be obtained from the echo signal. An annular scanning tomographic image is obtained by arranging the piezoelectric vibrators in an annular shape and sequentially scanning them, and a state around 360 degrees of a lumen wall such as a blood vessel is diagnosed together with the surface information and the tomographic information of the object. Will be able to do things.

Next, referring to FIGS. 9A to 9D, the third
As an embodiment, an ultrasonic transducer used in the ultrasonic diagnostic apparatus of the present invention will be described. Here, differences from the configuration of the above-described second embodiment will be described. 8 and 9, in the structure of the ultrasonic transducer catheter, it is the same that a plurality of piezoelectric vibrators are formed. However, in the present embodiment, the piezoelectric vibrators 82a to 82a The point where the ultrasonic delay medium 80 is provided on the front surface of 82h and the acoustic coupling layer and pressure receiving portion are not formed directly on the piezoelectric vibrator but are formed on the contact surface of the ultrasonic delay medium 80 with the object. The point is different.

FIG. 10 shows an example of the configuration of an ultrasonic diagnostic apparatus for carrying out the present embodiment. In this configuration, parts that are the same as the parts shown in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted. This ultrasonic diagnostic apparatus uses the first
This is a simple configuration in which the branch circuit 2, the attenuator 5, the delay circuit 7, and the differential amplifier 6 are removed from the configuration of the embodiment.

In FIG. 10, the trapezoidal pulse signal 16 from the trapezoidal pulse generator 1 is
It is amplified to a signal 18 of の 100 V and applied to the ultrasonic transducer 66.

In the ultrasonic transducer, as shown in FIG. 9D, a plurality of piezoelectric vibrators 82a to 82h are mounted on a single ultrasonic delay medium 80. Piezoelectric vibrator 8
The ultrasonic vibrations generated at 2a to 82h propagate through the ultrasonic delay medium 80 by t _d / 2, and the surface t of the object 75
It reaches _d / 2 and receives a change in center frequency and a change in amplitude according to the viscoelastic properties of the surface of the object.

The ultrasonic response signal after being affected by this
This is the ultrasonic signal 29 shown in FIG.
By applying the trapezoidal pulse 30 in a state where the object 75 is not in contact with the center frequency and amplitude of the response signal 9 and comparing the center frequency and amplitude of the response signal generated after the time t _d , the surface viscoelasticity of the object is obtained. Characteristics can be detected. As shown in FIG. 11, the ultrasonic response waveform at the time of contact with the object is the echo signal 3 following the ultrasonic response signal 29 including the first surface information.
1, 32, 33, 34, etc. are observed. Each of these signals is subjected to FFT processing, and the center frequency,
By extracting parameters of amplitude and phase and comparing them,
It is possible to know the viscoelastic characteristic ratio between the target object and the abnormal tissue existing inside the target object. The above is sequentially switched for each ultrasonic transducer.

According to this embodiment, the response signal immediately after the ultrasonic wave reaches the surface of the object can be detected separately from the applied trapezoidal pulse waveform, and can be compared with the response signal when the object is not in contact. Thereby, the viscoelastic characteristics of the surface of the object can be detected. Further, the viscoelastic characteristic in the depth direction of the object can be detected from the echo signal observed following the immediately following response signal. Further, in the ultrasonic transducer, since the piezoelectric vibrator does not directly come into contact with an object such as a living body, not only is there no concern about current leakage to the living body, but also there is no worry about damage to the ultrasonic transducer for cleaning and disinfection.

Next, a modification of the above-described third embodiment will be described with reference to FIG. This modification differs from the third embodiment only in the structure of the piezoelectric vibrator. That is, the number of the partial electrodes 8 corresponding to the number of elements (eight in the example of FIG. 12) is added to the dish-shaped annular piezoelectric ceramics 85.
6a to 86h and the whole surface electrodes (not shown) are applied to the back surface, and after the partial electrodes are formed, they are all polarized at the same potential, and bonded by a method such as adhesion so that the whole electrode side comes into contact with the ultrasonic delay medium.

The lead wires 87a to 87a to 8
7h, and a trapezoidal pulse voltage is applied between the lead wire and the surface ground electrode 99 formed on the surface of the fitting portion 80a of the ultrasonic delay medium.

In this modification, it is not necessary to join the piezoelectric vibrators one by one as in the third embodiment, and it is not necessary to pay attention to variations in characteristics among the piezoelectric vibrators due to assembly. Further, each piezoelectric vibrator part has a curved surface, and ultrasonic waves are emitted from the concave side of the curved surface, so that the ultrasonic beam is narrowed,
Stray of the ultrasonic beam is less likely to occur. As a result, it becomes possible to detect the ultrasonic response and the echo signal immediately after the high accuracy. Note that, in this embodiment, the piezoelectric vibrator is disposed on the side not in contact with the object with respect to the delay medium, but the position of the piezoelectric vibrator is the same as in the above-described second embodiment. Needless to say, the configuration provided on the side in contact with the object is also within the scope of the present invention.

Further, the ultrasonic diagnostic apparatus of the present invention is not limited to the conventional ultrasonic diagnostic apparatus, but includes conventional tactile sensors and pressure sensors as long as they use ultrasonic vibration for detection. thinking.

Although the above embodiments have been described, the present specification also includes inventions for solving the following problems. As a problem, if the high-frequency pulse signal corresponding to only the ultrasonic response signal immediately after the above can be separated, the first problem can be achieved. However, with this alone, the surface and deep portions of the object to be inspected can be achieved. This does not mean that the acoustic structure can be detected with high sensitivity and high resolution. In particular, when detecting deep information, the pulse width of the echo signal has a great effect.

Generally, the pulse width of the echo signal is almost determined by the pulse width of the immediately following ultrasonic response signal. In the prior art, as shown in FIG. 14, the ultrasonic vibration is damped by the structure of the ultrasonic transducer in which the back load member 109 is formed on the back surface of the piezoelectric element 107 to shorten the pulse width. I have.

As in the case of the conventional ultrasonic diagnostic apparatus, when only the echo signal is processed for the purpose of detecting only the deep information, this may be used. However, not only the deep information but also the surface information, that is, the tactile information is detected with high sensitivity. In such a case, if the immediately following ultrasonic response signal is damped from the beginning, there is a problem that a desired detection sensitivity cannot be obtained. Therefore, in order to detect surface information, that is, tactile information with high sensitivity, the immediately following ultrasonic response signal is not damped from the beginning, and it is necessary that the pulse width of the ultrasonic pulse can be shortened in order to increase the resolution of deep diagnosis. .

When the immediately following ultrasonic response signal can be used by solving the above technical problems, it becomes meaningful to derive a relationship between this signal and a signal subsequent thereto. In the past, the position of what kind of acoustic discontinuity was simply depicted based on the relationship between the time at which the echo signal was detected and the magnitude of the echo amplitude. It does not depict the viscoelastic properties of the living tissue existing at the position up to the continuous part or the viscoelastic properties of the abnormal tissue. However, a more preferable ultrasonic diagnosis is to be able to diagnose what kind of abnormal tissue is located at which position in normal living tissue and how much abnormality is compared to normal living tissue. .

Therefore, there is a problem that it is necessary to be able to express, at an absolute value or a relative value, what position and how much abnormal tissue is present at which position in a normal living tissue. Further, when performing ultrasonic diagnosis of a living tissue, a certain degree of diagnosis can be performed without scanning an ultrasonic beam. However, if surface information is obtained by scanning an ultrasonic beam, the accuracy of diagnosis is further improved. In order to obtain such surface information, there is a method in which a single ultrasonic transducer is rotated and an ultrasonic beam is scanned, as in the related art, but as in the object of the present invention,
In order to detect the acoustic structure over the surface and deep portion of the test object, the ultrasonic transmitting / receiving surface of the ultrasonic transducer needs to be in contact with the surface of the test object. There is a problem that it cannot be rotated, and it is necessary to use an electronic scanning ultrasonic transducer. The electronic scanning ultrasonic transducer must be used.

(1) An ultrasonic transducer comprising a piezoelectric vibrator, a pulser / receiver for applying a pulse voltage to the ultrasonic transducer, and receiving an ultrasonic response signal generated in the ultrasonic transducer by applying the pulse voltage; Means for processing the output signal of the pulsar / receiver, and analyzing the output signal to detect the acoustic structure of the test object. An ultrasonic diagnostic apparatus comprising means for separating, detecting and analyzing an ultrasonic response signal.

However, the immediately following ultrasonic response signal is the first ultrasonic signal that has acted on the object. The pulser / receiver is a commonly used integrated device. The pulser includes a pulse generator, a pulse width, a pulse generation cycle setting unit, a time constant setting unit, and the like. It is a device composed of circuits and the like. When a pulse voltage is applied from the pulsar to an ultrasonic transducer composed of a piezoelectric vibrator, the ultrasonic transducer generates an ultrasonic response signal having a frequency component equal to the inherent resonance frequency of the piezoelectric vibrator.

This signal is converted into a high-frequency pulse voltage signal by the piezoelectric effect of the piezoelectric vibrator. Among the voltage signals, the voltage signal generated immediately after the application of the pulse voltage includes a high-frequency pulse voltage signal obtained by piezoelectrically converting the applied pulse voltage signal and the immediately following ultrasonic response signal. Of these, the immediate ultrasonic response signal includes a tactile signal corresponding to the surface state of the object. Therefore, if there is a means for separating and detecting the ultrasonic response signal immediately after the application of the pulse voltage and analyzing the ultrasonic response signal, the effect of diagnosing the surface state of the object can be obtained.

(2) In the ultrasonic diagnostic apparatus according to the above mode (1), the means for separating and detecting only the immediately following ultrasonic response signal includes: means for branching the output of the pulse generator (pulsar); Means for amplifying one of the signals, a response signal immediately after voltage application of the amplified signal to the ultrasonic transducer, attenuation means for reducing the amplitude of the signal immediately after, and delaying the other signal of the branch signal An ultrasonic diagnostic apparatus comprising: means for causing the delay output; and means for obtaining a difference between the delayed output and the attenuated output.

The first embodiment corresponds to this. The ultrasonic diagnostic apparatus according to the above mode (1) is a pulse generator (pulsar).
The pulse output is branched, one of which is branched as a reference signal, and the other as an ultrasonic excitation signal for applying a pulse voltage to the ultrasonic transducer after being amplified by the amplification means. Used. The application of the ultrasonic excitation signal excites the ultrasonic response signal immediately after the ultrasonic transducer. However, there is almost no time difference between the applied pulse voltage signal and the high-frequency pulse voltage signal obtained by piezoelectrically converting the ultrasonic response signal. Therefore, it is observed as a superimposed signal of both. Since this superimposed signal has a high voltage, it is attenuated to an appropriate amplitude by the attenuating means. On the other hand, the reference signal gives a time delay equal to the total time delay due to the amplifying means, attenuating means, and wiring existing in the other signal transmission path. Then, the two signals are input to a means for obtaining a difference, and a differential output is obtained. By using these means, only the immediately following ultrasonic response signal can be separated and detected, and the surface condition of the object can be diagnosed.

(3) In the ultrasonic diagnostic apparatus according to the above mode (1), the means for separating and detecting only the immediately following ultrasonic response signal has a low-loss ultrasonic delay medium and a gate means. Ultrasound diagnostic equipment.

The second embodiment corresponds to the second embodiment. However, in the second embodiment, the low-loss ultrasonic delay medium is exemplified by fused quartz, but other materials may also have a loss due to, for example, silicon, lithium niobate, crystallized glass, or vibration. Less material, specifically, attenuation factor α <0.1dB /
It should be about cm. In addition, if it is known that only an object having a small ultrasonic loss is measured, it is not always necessary to use an ultrasonic loss equivalent to that of fused silica, and α <5d
B / cm should be enough.

Accordingly, the item (3) is that the ultrasonic wave generated in the piezoelectric vibrator is applied to the object through the low-loss ultrasonic delay medium, and the response signal at this time is transmitted through the low-loss ultrasonic delay medium. The signal is returned to the piezoelectric vibrator and converted into a high-frequency pulse voltage signal by the piezoelectric effect of the piezoelectric vibrator. Since the high-frequency pulse voltage signal in this case is delayed from the pulse voltage application timing by the time that the ultrasonic wave generated in the piezoelectric vibrator reciprocates in the low-loss ultrasonic delay medium, the gate means for transmitting only the signal after the lapse of this time Through. The signal passing through the gate means does not include the voltage waveform applied to the piezoelectric vibrator.

By the above means, only the immediately following ultrasonic response signal from the object can be separated and detected, and the surface condition of the object can be diagnosed. (4) In the ultrasonic diagnostic apparatus according to the above (1), the means for applying the pulse voltage includes an ultrasonic wave having a time region electrically damped and a time region not damped. An ultrasonic diagnostic apparatus comprising means for generating pulse vibration.

All the embodiments are applicable. Therefore, in the above item (4), immediately after the application of the pulse voltage, the ultrasonic pulse vibration generated in the piezoelectric vibrator has almost no vibration amplitude in the electrically damped time region, and is thus damped. In the time range where the piezoelectric vibrator is not operated, the piezoelectric vibrator has a large vibration amplitude because it vibrates freely without any influence. Therefore, when an object load is applied, the ultrasonic pulse vibration in the time region where the damping is not performed changes greatly when the object load is applied. Further, as described above, since the tailing portion originally included in the ultrasonic pulse is electrically damped, the pulse width of the ultrasonic pulse can be shortened.
By the above means, it is possible to detect the surface information of the target object with high sensitivity.

[0092] (5) above (4) In the ultrasonic diagnostic apparatus according to claim, means for applying a pulse voltage the is, the voltage rise time t _r, the voltage holding time t _w, the voltage fall time t _f the have the When t _p the inverse of the resonance frequency of the piezoelectric transducer elements constituting each ultrasonic _{transducer, t r <t p <t} f t w = n × t p (n = 1~5) t f = m × t _p (m = 1~10) means for generating a trapezoidal pulse having a relationship, the ultrasonic diagnostic apparatus further comprising a means for amplifying a trapezoid pulse.

All the embodiments are applicable. Where m, n
Is not necessarily an integer, but indicates a real number. In addition, since the piezoelectric vibrator is a differential element, when the applied voltage increases and when the applied voltage decreases, the piezoelectric vibrator generates vibrations whose phases are inverted.

[0094] Therefore, the item (5), given the rise of the step-up voltage of the reciprocal t _p shorter time t _r of the resonance frequency of the piezoelectric vibrator, the piezoelectric vibrator is free vibration at a resonant frequency, to contrast, longer than the inverse t _p time t _f
Is applied, the time t
The piezoelectric vibrator vibrates at the resonance frequency corresponding to f. Therefore, have the appropriate t _w, the t _r, t _p, t _f
When a trapezoidal pulse having the following relationship is applied, it is possible to generate ultrasonic pulse vibration composed of an electrically damped time region and an undamped time region.

By the above means, the surface information of the object can be detected with high sensitivity, and an ultrasonic response signal having a short pulse width can be used. (6) In the ultrasonic diagnostic apparatus according to the above mode (5), the means for generating the trapezoidal pulse has a variable signal input means for changing the values of m and n. Ultrasound diagnostic device characterized by the following.

All the embodiments are applicable. Therefore, the item (6) has a variable signal input means for changing the values of m and n, so that the variable signal is input and the optimum trapezoidal pulse signal from which the optimum ultrasonic response signal is obtained is generated. It is possible to do. However, the value of m determines the wave number of the ultrasonic response waveform. When the wave number increases, the pulse width increases and the resolution is adversely affected.
The ultrasonic energy of the ultrasonic pulse increases as the wave number increases, contributing to an increase in the dynamic range. Therefore,
If the function of adjusting the t _w, t _f trapezoidal pulses, greater sensitivity of the surface information of the object and makes it possible to detect a large dynamic range, ultrasonic response signal with a short pulse width can be utilized.

(7) In the ultrasonic diagnostic apparatus described in the above item (6), after the value of the above n is set to the value of the above m, the electrical damping described in the above item (5) is performed. An ultrasonic diagnostic apparatus comprising means for automatically setting a maximum amplitude in a time domain to be minimum.

All the embodiments are applicable. Therefore, in the above item (7), if the value of m can be automatically set, an optimum ultrasonic response waveform can be obtained even if the ultrasonic transducer used is replaced.

(8) In the ultrasonic diagnostic apparatus according to the above (1), the means for detecting and analyzing the ultrasonic response signal immediately after the application of the pulse voltage is used to determine the center frequency from the immediately following ultrasonic response signal. An ultrasonic diagnostic apparatus comprising means for extracting parameters of f ₀ and the maximum amplitude A ₀ .

All the embodiments are applicable. However, the means for extracting the parameters of the center frequency f ₀ and the maximum amplitude A ₀ uses the ultrasonic response signal with respect to the time axis in the embodiment as FF.
After T processing, parameters are extracted.

[0102] Therefore, the (8) section, ultrasonic response signal immediately after corresponding to the magnitude of the presence or object loads the object load, since the center frequency and the amplitude changes, a center frequency f ₀ By knowing these changes by means of extracting the maximum amplitude _A0 as a parameter, the presence or absence of the object load and the magnitude of the object load can be known.

(9) The ultrasonic diagnostic apparatus according to the above (1), further comprising means for detecting and analyzing an ultrasonic response signal following the immediately following ultrasonic response signal. Ultrasound diagnostic device.

However, the following ultrasonic response signal is
Means ultrasonic echo signal. All embodiments correspond. Therefore, the term (9) is equivalent to the immediately following ultrasonic response signal S.
_{From 0,} it became possible to detect the surface information of the object. Subsequent ultrasonic response signals show that when an ultrasonic pulse propagating deep from the surface of the object encounters tissue with an acoustic impedance different from that of the propagation medium, the ultrasonic pulse is reflected at the boundary. Then, the echo signal Se1 returns to the ultrasonic transducer. Further, the ultrasonic pulse transmitted through the boundary surface passes through the reflection at the next boundary surface, returns to the first boundary surface, and partially transmits through the boundary surface to become an echo signal Se2. Return to the ultrasonic transducer.

The echo signal S ₀ and the echo signal Se 1
The sound velocity of the propagation medium can be determined from the relationship, and the attenuation of the propagation medium can be determined from the amplitude ratio. The sound velocity of the tissue having the different acoustic impedance is known from the relationship between Se1 and Se2, and the attenuation of the tissue having the different acoustic impedance is known from the amplitude ratio.

Since the speed of sound and the attenuation are related to the elasticity and viscosity of the viscoelastic properties, respectively, the means for detecting and analyzing the ultrasonic response signal following the ultrasonic response signal immediately after is added, so that only the surface can be detected. But not deep viscoelastic properties.

(10) In the ultrasonic diagnostic apparatus according to the above mode (9), means for measuring a time interval between the immediately succeeding ultrasonic response signal and the succeeding ultrasonic response signal, An ultrasonic diagnostic apparatus comprising means for measuring a time interval between ultrasonic response signals.

All the embodiments are applicable. Therefore, the above-mentioned item (10) has the same operation and effect as the item (9). (11) In the ultrasonic diagnostic apparatus according to the above mode (9), means for measuring a maximum amplitude ratio between the immediately succeeding ultrasonic response signal and a succeeding ultrasonic response signal, and a plurality of succeeding ultrasonic waves An ultrasonic diagnostic apparatus comprising means for measuring a time interval between response signals.

All the embodiments are applicable. Therefore, the above-mentioned item (11) has the same effect as the item (9). (12) The ultrasonic diagnostic apparatus according to the above (9), further comprising means for measuring a relationship between a phase of the immediately following ultrasonic response signal and a phase of a succeeding ultrasonic response signal. Ultrasonic diagnostic equipment.

All the embodiments are applicable. Therefore, the above-mentioned item (12) has the same operation and effect as the item (9). (13) In the ultrasonic diagnostic apparatus according to the above mode (4), the ultrasonic transducer is subjected to a stress load for ultrasonic vibration on a surface of the ultrasonic transducer opposite to an ultrasonic transmitting / receiving side. An ultrasonic diagnostic apparatus characterized by having no structure.

All the embodiments are applicable. Therefore, the item (13) has a structure in which the ultrasonic transducer does not bond the back load material at all, and thus the electrically damped time region and the damping are not damped as described in the item (4). Ultrasonic pulse vibration composed of a time domain can be generated. Therefore, a change in the center frequency or amplitude of the ultrasonic pulse vibration when the object comes into contact can be detected with high sensitivity and a high dynamic range.

(14) In the ultrasonic diagnostic apparatus according to the above mode (13), the transducer is connected to the piezoelectric vibrator, the acoustic coupling layer joined to the surface on the ultrasonic wave emitting side, and the acoustic coupling layer joined to the acoustic coupling layer. An ultrasonic diagnostic apparatus characterized by comprising a pressure receiving portion.

All the embodiments are applicable. Therefore, in the above item (14), the ultrasonic wave excited by the piezoelectric vibrator passes through the acoustic coupling layer, a part of the ultrasonic wave efficiently penetrates through the pressure receiving portion in the depth direction of the object, and the other part is immediately after the ultrasonic wave. It is used for surface information detection as a sound wave response signal. When optimally acoustically coupled, large amounts of ultrasonic energy penetrate into the object and reach the acoustic interface even with highly attenuated objects, where reflected ultrasonic echo signals can be detected and even with highly attenuated objects. The modulus of elasticity and viscosity can be evaluated.

(15) In the ultrasonic diagnostic apparatus according to the above mode (13), the ultrasonic transducer may be provided on the surface of the piezoelectric vibrator on the side of transmitting and receiving the ultrasonic waves with the low-loss ultrasonic delay described in the above mode (4). An ultrasonic diagnostic apparatus having a structure in which a medium is joined and an acoustic matching layer serving also as a pressure receiving portion is formed on the surface of the low-loss ultrasonic delay medium on the side in contact with the object.

The second embodiment corresponds to this. Therefore, in the above item (15), the structure of the ultrasonic transducer joins a low-loss ultrasonic delay medium, and the back surface is formed on the back surface so as to be a load of ultrasonic vibration of the piezoelectric vibrator. There is no structure.

The ultrasonic vibration excited by the piezoelectric vibrator propagates through the low-loss ultrasonic delay medium, reaches the object, and
The component is divided into a component reflected at the interface and a component penetrating into the object. The former component is used as the immediately following ultrasonic response signal, surface information of the object is detected from this signal, and the latter component is used to generate an echo signal, and deep information is detected from the echo signal. Since an acoustic matching layer is formed between the low-loss ultrasonic delay medium and the object, multiple reflections in the low-loss ultrasonic delay medium are reduced, and the surface information and the deep information can be detected appropriately. . Further, since the piezoelectric vibrator does not come into direct contact with the object, when the object is a living body,
An effect of completely eliminating concerns about safety can also be obtained. Further, the problem of chemical resistance at the time of cleaning and disinfecting the ultrasonic transducer is completely eliminated.

(16) In the ultrasonic diagnostic apparatus according to the above mode (15), the ultrasonic transducer may be
A plurality of piezoelectric vibrators are joined to one low-loss ultrasonic delay medium, and the surface of the low-loss ultrasonic delay medium on the diagonal side sandwiching the low-loss ultrasonic delay medium of the plurality of piezoelectric vibrators, An ultrasonic diagnostic apparatus having a structure in which a pressure receiving portion for transmitting and receiving ultrasonic waves is formed.

The second embodiment corresponds to this. Therefore, the item (16) has the effect of (1) in addition to the effect of the item (15).
Since a plurality of piezoelectric transducers are bonded to one low-loss ultrasonic delay medium, the piezoelectric transducer that is in contact with the object via the low-loss ultrasonic delay medium can be used without changing the posture of the ultrasonic transducer. The object can be used to diagnose the object. Also,
The signal of the piezoelectric vibrator that is not in contact with the object via the low-loss ultrasonic delay medium is used as a reference signal. Unnecessary characteristics that commonly occur can also be corrected.

(17) In the ultrasonic diagnostic apparatus according to the above mode (16), the plurality of piezoelectric vibrators are arranged in a ring, and the ultrasonic transmitting / receiving surface of the low-loss ultrasonic delay medium is also diagonal. An ultrasonic diagnostic apparatus characterized by being formed in a ring shape.

The second and third embodiments correspond to this. Therefore, in the above (17), in the embodiment described in the above item (16), the number of the piezoelectric vibrators arranged in a ring is eight, but this number is not necessarily the best, and it depends on the application. The number may be larger or smaller, and may be designed according to the application. Also, it is described that a plurality of discrete piezoelectric elements are joined. For example, a thick piezoelectric film or a thin piezoelectric film is formed via a lower electrode on an ultrasonic delay medium having high heat resistance and good film forming properties, and Alternatively, a structure in which an upper electrode is formed and wiring is performed may be used.

Therefore, the ultrasonic beam can be circularly scanned by arranging a plurality of piezoelectric vibrators in a ring shape and sequentially performing drive scanning along the ring shape. This eliminates the need to mechanically rotate the ultrasonic transducer in a circular manner as in the prior art, greatly reducing mechanical structural parts, and greatly improving the reliability of the apparatus.

(18) In the ultrasonic diagnostic apparatus according to the above mode (17), the plurality of piezoelectric vibrators arranged in a ring have a structure in which a split electrode is formed on a ring-shaped piezoelectric element. Ultrasonic diagnostic equipment. The second and third embodiments correspond to this. Therefore, the above item (18) corresponds to the above item (1).
The same operation and effect as in the item (7) can be obtained.

[0122]

As described above in detail, according to the present invention, it is possible to provide an ultrasonic diagnostic apparatus capable of detecting an acoustic structure over a surface and a deep portion of a test object.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of an ultrasonic diagnostic apparatus according to a first embodiment.

FIG. 2 is a diagram schematically showing an ultrasonic response waveform in the ultrasonic diagnostic apparatus shown in FIG.

FIG. 3 is a diagram showing an example of an internal configuration of a trapezoidal pulse generator in the ultrasonic diagnostic apparatus shown in FIG.

FIG. 4 is a diagram for explaining the principle of dynamic damping in the ultrasonic diagnostic apparatus according to the first embodiment.

FIG. 5 is a diagram showing an ultrasonic response waveform obtained by a method conventionally used in a normal ultrasonic diagnostic apparatus.

FIG. 6 is a diagram illustrating a configuration example of an ultrasonic transducer used in the ultrasonic diagnostic apparatus according to the first embodiment.

FIG. 7 is a diagram showing a modified example of the ultrasonic transducer shown in FIG.

FIG. 8 is a diagram showing a configuration of an ultrasonic transducer used in the ultrasonic diagnostic apparatus of the present invention as a second embodiment.

FIG. 9 is a diagram showing a configuration of an ultrasonic transducer used in an ultrasonic diagnostic apparatus of the present invention as a third embodiment.

FIG. 10 is a diagram illustrating a configuration example of an ultrasonic diagnostic apparatus for implementing a third embodiment.

11 is a diagram schematically showing an ultrasonic response waveform in FIG.

FIG. 12 is a diagram illustrating a modified example of the ultrasonic transducer used in the ultrasonic diagnostic apparatus according to the third embodiment.

FIG. 13 is a diagram showing a configuration of a conventional ultrasonic transducer catheter.

FIG. 14 is a diagram showing a configuration of a conventional ultrasonic transducer.

FIG. 15 is a diagram illustrating a configuration example of a conventional ultrasonic diagnostic apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 trapezoidal pulse generator 2 branch circuit 3 high-frequency amplifier 4 ultrasonic transducer 5 attenuator 6 differential amplifier 7 delay circuit 8 high-frequency amplifier 9 FFT circuit 10 gate timing setting unit 11, 59 Gate circuit 12 ... Maximum value detector 13 ... N value setting circuit 14 ... Changeover switch 15 ... Trapezoidal pulse waveform controller 16-28 ... Signal

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mineyuki Maezawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd.

Claims (3)

[Claims] 1. An ultrasonic diagnostic apparatus for detecting an acoustic structure of an object using ultrasonic waves, comprising: an ultrasonic transducer configured to generate ultrasonic waves radiated to the object, the ultrasonic transducer including a piezoelectric vibrator; Generate a predetermined pulse signal, apply the pulse signal to the ultrasonic transducer, generate an ultrasonic wave, irradiate the object, receive the reflected ultrasonic wave, and output it as an ultrasonic response signal Pulse generation / reception means, and among the ultrasonic response signals output from the pulse generation / reception means, separate and detect only the ultrasonic response signal that has acted on the object first and immediately after the application of the pulse signal. An ultrasonic diagnostic apparatus, comprising: 2. The separating and detecting unit includes: a branching unit that branches a pulse signal generated by the pulse generating / receiving unit into at least two equivalent signals; and an amplifier that amplifies one of the branched signals branched by the branching unit. Amplifying means, and a signal responding immediately after applying the amplified signal from the amplifying means to the ultrasonic transducer is input as the immediately following ultrasonic response signal, and the amplitude of the immediately following ultrasonic response signal is predetermined. Attenuating means for reducing the value to a value, a means for delaying the other branch signal branched by the branching means, and a difference means for taking a difference between a delay output from the delay means and an attenuation output from the attenuation means. The ultrasonic diagnostic apparatus according to claim 1, wherein: 3. The ultrasonic diagnostic apparatus according to claim 1, wherein said separation detecting means includes a low-loss ultrasonic delay medium and a gate means for separating and detecting only the immediately following ultrasonic response signal. .