JP4747300B2 - Acoustic impedance measurement method, acoustic impedance measurement device, object characteristic evaluation method, and object characteristic evaluation device - Google Patents

Description

  The present invention relates to an acoustic impedance measurement method, an acoustic impedance measurement device, an object property evaluation method, and an object property evaluation device using ultrasonic waves.

  The acoustic impedance is determined by the product of density and sound velocity, and is used as a parameter reflecting hardness. Specifically, for example, a technique for measuring the acoustic impedance of soft tissue (surface layer portion) and bone (core portion) and diagnosing osteoporosis based on the measured value has been proposed (see, for example, Patent Document 1). ).

  The acoustic impedance measuring device described in Patent Literature 1 includes a transducer for irradiating an object with ultrasonic waves. This transducer is composed of an ultrasonic sensor composed mainly of an ultrasonic vibrator and an intermediate medium joined to the ultrasonic sensor. In this apparatus, by supplying a pulse signal, the ultrasonic transducer vibrates and is irradiated with ultrasonic waves.

  In this acoustic impedance measuring apparatus, when measuring the acoustic impedance of an object to be inspected (soft tissue and bone), first, as an initial calibration, the transducer is set in the air, and the ultrasonic wave is irradiated from the transducer, so that the intermediate medium and the air The reflected wave signal from the boundary surface is acquired. Then, in a state where the transducer is in contact with a calibration medium having a known acoustic impedance, a reflected wave signal from the boundary surface between the intermediate medium and the calibration medium is acquired by irradiating ultrasonic waves from the transducer. And using the relational expression of the sound pressure reflection coefficient, the reflected wave signal from the interface between the intermediate medium and the air, the reflected wave signal from the interface between the intermediate medium and the calibration medium, the acoustic impedance of the air, Based on the acoustic impedance of the calibration medium, the acoustic impedance of the intermediate medium is calculated.

Next, the ultrasonic wave is irradiated from the transducer while the transducer is in contact with the surface of the soft tissue, so that the reflected wave signal from the interface between the intermediate medium and the soft tissue and the reflection from the interface between the soft tissue and the bone are reflected. A wave signal is acquired. Then, using the relational expression of the sound pressure reflection coefficient, the acoustic impedance of the soft tissue is obtained based on the reflected wave signal from the boundary surface between the intermediate medium and the soft tissue and the acoustic impedance of the intermediate medium. Furthermore, the acoustic impedance of the bone is obtained based on the reflected wave signal from the boundary surface between the soft tissue and the bone and the acoustic impedance of the soft tissue, and osteoporosis is diagnosed according to the acoustic impedance.
JP 2000-102537 A

  By the way, in the acoustic impedance measuring apparatus of patent document 1, initial calibration is performed prior to measuring the acoustic impedance of the object to be inspected. In this initial calibration, it is necessary to irradiate ultrasonic waves toward the calibration medium after irradiating ultrasonic waves into the air. Therefore, in order to measure the acoustic impedance of the object to be inspected, it is necessary to irradiate ultrasonic waves a plurality of times. In addition, since it is necessary to obtain the acoustic impedance of the object to be inspected after obtaining the acoustic impedance of the intermediate medium, there is a problem that the calculation process becomes complicated, the measurement time becomes long, and the apparatus size becomes large. Arise.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an acoustic parameter measuring method and an acoustic parameter measuring apparatus that can quickly measure the acoustic impedance of an object to be inspected with a simple configuration. There is. Another object is to provide an object characteristic evaluation method and an object characteristic evaluation apparatus capable of quickly performing characteristic evaluation of an inspection object with a simple configuration.

  In order to solve the above-mentioned problem, in the invention according to claim 1, an acoustic impedance measurement method is provided in which an ultrasonic wave is irradiated onto an inspection object, and an acoustic impedance of the inspection object is measured based on the obtained reflected wave. An ultrasonic transducer having a known intrinsic acoustic impedance and vibration surface and the object to be inspected, and the ultrasonic transducer and the object to be inspected between the ultrasonic transducer and the object to be inspected Interposing an ultrasonic transmission body having a known intrinsic acoustic impedance different from the object to be inspected, irradiating ultrasonic waves from the ultrasonic transducer toward the object to be inspected, and applying the irradiated ultrasonic waves to the object An nth-order reflected wave (where n is a natural number) and m that are reflected in a multi-dimensional manner on the surface of the object to be inspected by reflection action on the vibration surface of the ultrasonic vibrator and reach the ultrasonic vibrator with a time difference. Next Detecting a signal intensity of a radiation wave (where m is a natural number larger than n), a signal intensity of the nth order reflected wave, a signal intensity of the mth order reflected wave, a specific acoustic impedance of the ultrasonic transmission body, and the And a step of calculating an acoustic impedance of the object to be inspected based on a specific acoustic impedance of the ultrasonic transducer.

  According to the first aspect of the present invention, the ultrasonic transmission body is interposed between the ultrasonic transducer and the inspection object, and the ultrasonic wave is irradiated from the ultrasonic transducer toward the inspection object. The ultrasonic transducer and the object to be inspected are opposed to each other via an ultrasonic transmission body, and the ultrasonic waves are reflected in a multi-dimensional manner on the surface of the object to be inspected by the reflection action on the vibration surface of the ultrasonic vibration. The At this time, the signal intensities of the n-th order reflected wave and the m-th order reflected wave, which are any two of the reflected waves, are detected. Then, the acoustic impedance of the object to be inspected is calculated based on the signal intensity of the nth-order reflected wave, the signal intensity of the mth-order reflected wave, the specific acoustic impedance of the ultrasonic transmission body, and the specific acoustic impedance of the ultrasonic transducer. According to this measuring method, it is not necessary to irradiate the ultrasonic wave a plurality of times as in the prior art, and the acoustic impedance of the object to be inspected can be obtained by irradiating the ultrasonic wave once from the ultrasonic transducer.

  The invention according to claim 2 is an acoustic impedance measuring apparatus for irradiating an inspection object with an ultrasonic wave and measuring an acoustic impedance of the inspection object based on the obtained reflected wave, and has a known intrinsic acoustic impedance. And a vibration surface capable of reflecting a reflected wave from the surface of the object to be inspected, converting an electric signal into vibration to generate an ultrasonic wave, and receiving the reflected wave and converting it into an electric signal An ultrasonic transducer that has a known intrinsic acoustic impedance different from that of the inspection object and the ultrasonic transducer, and a proximal end is joined to the vibration surface of the ultrasonic transducer, while a distal end is An ultrasonic transmission body arranged so as to be in direct contact with the object to be inspected, and an nth-order reflected wave that reaches the ultrasonic transducer with a time difference due to a reflection action on the vibration surface of the ultrasonic transducer (however, n is a natural number) and A signal intensity detecting means for detecting the signal intensity based on the second reflected wave (where m is a natural number larger than n), the signal intensity of the nth reflected wave, the signal intensity of the mth reflected wave, the super The gist of the present invention is an acoustic impedance measuring apparatus, comprising: an arithmetic unit that calculates the acoustic impedance of the object to be inspected based on the intrinsic acoustic impedance of the acoustic wave transmitter and the intrinsic acoustic impedance of the ultrasonic transducer. .

  According to the second aspect of the present invention, the base end of the ultrasonic transmission body is joined to the vibration surface of the ultrasonic transducer, and the front end thereof is arranged to directly contact the object to be inspected. Then, the ultrasonic transducer converts the electrical signal into vibration, so that the object to be inspected is irradiated from the vibration surface of the ultrasonic transducer via the ultrasonic transmission body. The ultrasonic transducer and the object to be inspected are opposed to each other via an ultrasonic transmission body, and the ultrasonic waves are reflected in a multi-dimensional manner on the surface of the object to be inspected by the reflection action on the vibration surface of the ultrasonic vibration. The At this time, the signal intensity detection means detects the signal intensity of the n-th order reflected wave and the m-th order reflected wave, which are arbitrary two of the reflected waves. Then, based on the signal intensity of the nth order reflected wave, the signal intensity of the mth order reflected wave, the specific acoustic impedance of the ultrasonic transmitter, and the specific acoustic impedance of the ultrasonic transducer, the calculation means calculates the acoustic impedance of the object to be inspected. Calculated. According to this acoustic impedance measuring apparatus, it is not necessary to irradiate ultrasonic waves a plurality of times as in the prior art, and the acoustic impedance of the object to be inspected can be obtained by irradiating ultrasonic waves once from the ultrasonic transducer. Further, in this measuring apparatus, the acoustic impedance can be easily obtained, and the processing circuit can be simplified as compared with the prior art. Therefore, it is possible to realize a measurement apparatus that can be carried by reducing the size of the apparatus.

  According to a third aspect of the present invention, in the second aspect, the nth-order reflected wave is reflected on the ultrasonic transducer as a result of the ultrasonic wave generated by the ultrasonic transducer being reflected from the surface of the inspection object. The primary reflected wave that arrives first, and the m-order reflected wave arrives next to the primary reflected wave as a result of the primary reflected wave reflected by the vibrating surface being reflected again by the surface of the inspection object. The gist is that it is a secondary reflected wave.

  As in the present invention, when ultrasonic waves are reflected in a multi-dimensional manner on the surface of an object to be inspected, the signal intensity of the reflected wave decreases each time reflection is repeated, and the reflected wave is electrically converted by an ultrasonic transducer. The time for conversion to a signal is also delayed. Therefore, as in the invention described in claim 3, by using the signal intensity of the primary reflected wave and the secondary reflected wave having a relatively large signal intensity and a quick time to reach the ultrasonic transducer, the acoustic impedance can be accurately determined. And can be quickly determined.

  According to a fourth aspect of the present invention, in the third aspect, the signal intensity detecting unit detects the primary reflected wave and the secondary reflected wave and outputs voltage values corresponding to the signal intensity to the calculating unit. The gist of the calculation means is to calculate the acoustic impedance of the inspection object based on the voltage values.

  According to the fourth aspect of the invention, the primary reflected wave and the secondary reflected wave are detected by the signal intensity detecting means, and a voltage value corresponding to the signal intensity of these reflected waves is output to the calculating means. Based on these voltage values, the calculation means can determine the relationship between the reflectance of the primary reflected wave and the secondary reflected wave, and can accurately calculate the acoustic impedance of the object to be inspected using the relationship. it can.

  The gist of a fifth aspect of the present invention is that the apparatus according to any one of the second to fourth aspects further includes a display device that displays the acoustic impedance calculated by the calculation means.

  According to the fifth aspect of the invention, since the acoustic impedance calculated by the computing means is displayed on the display device, the property of the object to be inspected can be easily confirmed based on the acoustic impedance.

  A sixth aspect of the present invention is the electronic device according to any one of the second to fifth aspects, further comprising a handpiece having a pen shape as a whole, and the ultrasonic transducer and the ultrasonic transmission body at a tip of the handpiece. The gist is that is arranged.

  According to the sixth aspect of the present invention, the user can measure the acoustic impedance of the object to be inspected by holding the handpiece by hand and bringing the ultrasonic transmission body at the tip thereof into contact with the object to be inspected. Therefore, an acoustic impedance measuring device with excellent operability can be realized. Moreover, it is preferable that the signal intensity detection means and the calculation means are accommodated in the handpiece, and it is preferable that the handpiece is provided with a display device. By adopting this configuration, a portable acoustic impedance measuring device can be realized.

  The invention according to claim 7 is a method of irradiating an object to be inspected with ultrasonic waves and evaluating the characteristics of the object to be inspected based on the obtained reflected wave. The ultrasonic transducer and the object to be inspected are arranged opposite to each other, and a known intrinsic acoustic impedance different from the ultrasonic transducer and the object to be inspected is provided between the ultrasonic transducer and the object to be inspected. A step of interposing an ultrasonic transmission body having, an ultrasonic wave irradiation from the ultrasonic vibrator toward the object to be inspected, and a reflection effect of the irradiated ultrasonic wave on the vibration surface of the ultrasonic vibrator The n-th order reflected wave (where n is a natural number) and the m-th order reflected wave (where m is a natural number greater than n) that are reflected in a multi-dimensional manner on the surface of the object to be inspected and reach the ultrasonic transducer with a time difference. ) To detect the signal strength And the characteristics of the object to be inspected based on the signal strength of the nth-order reflected wave, the signal strength of the mth-order reflected wave, the specific acoustic impedance of the ultrasonic transmitter, and the specific acoustic impedance of the ultrasonic transducer The gist of the object characteristic evaluation method using ultrasonic waves, including the step of calculating a parameter as an element for evaluation.

  According to the seventh aspect of the present invention, the ultrasonic transmission body is interposed between the ultrasonic transducer and the inspection object, and the ultrasonic wave is irradiated from the ultrasonic transducer toward the inspection object. The ultrasonic transducer and the object to be inspected are opposed to each other via an ultrasonic transmission body, and the ultrasonic waves are reflected in a multi-dimensional manner on the surface of the object to be inspected by the reflection action on the vibration surface of the ultrasonic vibration. The At this time, the signal intensities of the n-th order reflected wave and the m-th order reflected wave, which are any two of the reflected waves, are detected. Based on the signal intensity of the n-th order reflected wave, the signal intensity of the m-th order reflected wave, the intrinsic acoustic impedance of the ultrasonic transmitter, and the intrinsic acoustic impedance of the ultrasonic transducer, The following parameters are calculated. According to this evaluation method, it is not necessary to irradiate the ultrasonic wave a plurality of times, and if the ultrasonic wave is irradiated once from the ultrasonic transducer, the parameter of the inspection object can be calculated, and the inspection object Characteristic evaluation can be performed quickly.

  The invention according to claim 8 is an apparatus for irradiating an object to be inspected with ultrasonic waves and evaluating the characteristics of the object to be inspected based on the obtained reflected wave, and having a known intrinsic acoustic impedance and An ultrasonic vibration having a vibration surface capable of reflecting a reflected wave from the surface of the object to be inspected, converting an electric signal into vibration to generate an ultrasonic wave, and receiving the reflected wave and converting it into an electric signal The child has a known specific acoustic impedance different from that of the object to be inspected and the ultrasonic transducer, and a base end is joined to the vibration surface of the ultrasonic transducer, while a tip is connected to the object to be inspected. An ultrasonic transmission body disposed so as to be in direct contact with the ultrasonic transducer, and an nth-order reflected wave that reaches the ultrasonic transducer with a time difference due to a reflection effect on the vibration surface of the ultrasonic transducer (n is a natural number) And m-th order reflected wave (where m is larger than n) Signal intensity detecting means for detecting the signal intensity based on the signal number, the signal intensity of the nth order reflected wave, the signal intensity of the mth order reflected wave, the intrinsic acoustic impedance of the ultrasonic transmitter and the super A gist of an object property evaluation apparatus using ultrasonic waves, comprising: an arithmetic unit that calculates a parameter as an element for characteristic evaluation of the inspection object based on a specific acoustic impedance of a sound wave oscillator And

  According to the eighth aspect of the present invention, the base end of the ultrasonic transmission body is joined to the vibration surface of the ultrasonic transducer, and the tip thereof is disposed so as to be in direct contact with the object to be inspected. Then, the ultrasonic transducer converts the electrical signal into vibration, so that the object to be inspected is irradiated from the vibration surface of the ultrasonic transducer via the ultrasonic transmission body. The ultrasonic transducer and the object to be inspected are opposed to each other via an ultrasonic transmission body, and the ultrasonic waves are reflected in a multi-dimensional manner on the surface of the object to be inspected by the reflection action on the vibration surface of the ultrasonic vibration. The At this time, the signal intensity detection means detects the signal intensity of the n-th order reflected wave and the m-th order reflected wave, which are arbitrary two of the reflected waves. Based on the signal strength of the nth order reflected wave, the signal strength of the mth order reflected wave, the specific acoustic impedance of the ultrasonic transmitter, and the specific acoustic impedance of the ultrasonic transducer, the calculation means evaluates the characteristics of the inspection object. A parameter as an element is calculated. According to this evaluation apparatus, it is not necessary to irradiate the ultrasonic wave a plurality of times, and if the ultrasonic wave is irradiated once from the ultrasonic transducer, the parameter of the inspected object can be obtained, and the characteristics of the inspected object accordingly. Evaluation can be performed quickly. In this evaluation apparatus, the parameter of the inspection object can be easily obtained, and the processing circuit can be simplified. Accordingly, it is possible to realize an evaluation apparatus that can be carried by downsizing the apparatus.

  As described in detail above, according to the first to sixth aspects of the invention, the acoustic impedance of the object to be inspected can be quickly measured with a simple configuration. Moreover, according to the invention of Claim 7, 8, the characteristic evaluation of a to-be-inspected object can be performed rapidly with a simple structure.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an acoustic impedance measuring apparatus.

  As shown in FIG. 1, the acoustic impedance measuring apparatus 1 includes a handpiece 2 that has a pen shape as a whole and an ultrasonic sensor 3 provided at the tip of the handpiece 2. The base end portion of the ultrasonic sensor 3 is fixed to the tip mounting opening of the handpiece 2 via a vibration damping member 4 such as rubber, and the ultrasonic sensor 3 is acoustically insulated from the handpiece 2. . When the apparatus is not used, a cap (not shown) may be put on the tip of the handpiece 2 to protect the ultrasonic sensor 3. The acoustic impedance measuring device 1 according to the present embodiment is a portable device, and the user measures the acoustic impedance by holding the handpiece 2 with a hand like a pen and pressing the ultrasonic sensor 3 against an object to be inspected. To do. In the acoustic impedance measuring apparatus 1, an operation panel 5 and a display 6 are provided on the outer peripheral surface of the handpiece 2, and various processing circuits are housed therein. The operation panel 5 and the display 6 may be provided on the upper end surface of the handpiece 2.

  FIG. 2 shows an electrical circuit configuration of the acoustic impedance measuring apparatus 1. As shown in FIG. 2, a transmitter 7, a receiver 8, a received voltage measuring device 9, a microcomputer (microcomputer) 10, and the like are accommodated in the handpiece 2 as processing circuits. The microcomputer 10 is electrically connected to the operation panel 5, the display 6, the transmitter 7, and the reception voltage measuring device 9, and the transmitter 7 and the receiver 8 are electrically connected to the ultrasonic sensor 3.

  As shown in FIGS. 1 and 2, the ultrasonic sensor 3 according to the present embodiment includes an ultrasonic transmission body 12 formed in a cylindrical shape using, for example, an acrylic resin, and titanic acid that is, for example, a piezoelectric ceramic. And an ultrasonic transducer 13 formed in a disk shape using lead zirconate (PZT). The ultrasonic transducer 13 has the same diameter as the ultrasonic transmission body 12. The proximal end of the ultrasonic transmission body 12 is joined to the vibration surface 14 of the ultrasonic vibrator 13, while the distal end of the ultrasonic transmission body 12 is disposed so as to be in direct contact with the object to be inspected (for example, biological tissue) 16. The That is, in this ultrasonic sensor 3, the ultrasonic transmission body 12 is interposed between the ultrasonic transducer 13 and the inspection object 16, and the inspection object 16 is disposed so as to face the ultrasonic transducer 13.

  For example, a power button 17 and a measurement start button 18 are provided on the operation panel 5, and a signal corresponding to the button operation is input to the microcomputer 10.

  The transmitter 7 generates an excitation pulse in response to the trigger signal input from the microcomputer 10 and outputs it to the ultrasonic sensor 3. Then, in the ultrasonic sensor 3, the excitation pulse is supplied to the ultrasonic transducer 13, and the ultrasonic transducer 13 vibrates, so that the ultrasonic wave is irradiated to the inspection object 16 through the ultrasonic transmission body 12. The In the present embodiment, in the ultrasonic transmission body 12, the ultrasonic transducer 13 is disposed at a position facing the inspection object 16. Therefore, the irradiated ultrasonic waves are reflected in a multi-dimensional manner on the surface of the inspection object 16 by the reflection action on the vibration surface 14 of the ultrasonic transducer 13.

  The ultrasonic transducer 13 of the ultrasonic sensor 3 is a transducer that is used for both transmission and reception, and converts the ultrasonic wave (reflected wave) reflected by the inspection object 16 into an electric signal.

  The receiver 8 includes a signal amplification circuit, a delay circuit, a gate circuit, and the like (not shown), amplifies the reflected wave signal converted by the ultrasonic transducer 13, and extracts the reflected wave signal. Specifically, a gate pulse is output from the delay circuit when a predetermined time has elapsed from the ultrasonic wave irradiation timing. Then, by operating the gate circuit in accordance with the gate pulse, a reflected wave signal of the primary reflected wave that reaches the ultrasonic transducer 13 first and the secondary reflected wave that reaches the ultrasonic transducer 13 is extracted.

  The reception voltage measuring device 9 includes an A / D converter 19 and A / D converts the voltage value (analog value) of the reflected wave signal input from the receiver 8 and converts the converted digital signal. Data is output to the microcomputer 10.

  The microcomputer 10 includes a CPU 21 that performs various arithmetic processes, a memory 22 that stores processing programs and data, and the like, and comprehensively controls the entire apparatus. The processing program includes a program for calculating the acoustic impedance and a program for displaying the calculated acoustic impedance on the display 6.

  Next, a method for measuring acoustic impedance in the present embodiment will be described. FIG. 3 is an explanatory diagram showing the measurement principle, and FIG. 4 is a timing chart showing operation waveforms of the acoustic impedance measuring apparatus 1.

As shown in FIGS. 3 and 4, the excitation pulse P is supplied to the ultrasonic transducer 13, and the ultrasonic transducer 13 is vibrated by the excitation pulse P, so that the ultrasonic transducer 13 is directed toward the inspection object 16. Then, an ultrasonic wave (incident wave) _So is irradiated. In the ultrasonic transmission body 12, the ultrasonic wave _So is the surface of the inspection object 16 (boundary surface between the ultrasonic transmission body 12 and the inspection object 16) and the vibration surface 14 (ultrasonic transmission body) of the ultrasonic transducer 13. 12 and the ultrasonic transducer 13). In the present embodiment, as a result of ultrasonic S _o is reflected by the surface of the object to be inspected 16, a primary reflected wave S _t1 which arrives first to the ultrasonic transducer 13, a primary reflector which is reflected by the vibrating surface 14 As a result of the wave S _t1 being reflected again on the surface of the object 16 to be inspected, the secondary reflected wave S _t2 that arrives next to the primary reflected wave S _t1 is extracted. Then, the voltage values V ₁ and V ₂ of those reflected wave signals are acquired.

The voltage values V ₁ and V ₂ of the reflected wave signal use the relationship between the sound pressure reflectances, the transmitted wave between the ultrasonic transducer 13 and the ultrasonic transmission body 12, the inspection object 16 and the ultrasonic transducer. When the reflected wave at 13 is considered, it can be expressed as the following equations (1) and (2).

Here, V ₀ is the ultrasonic voltage value corresponding to the (incident wave) S _o generated by the ultrasonic oscillator 13, Z ₁ is the acoustic impedance of the ultrasonic transducer 13. Z ₂ is the acoustic impedance of the ultrasonic transmission body (acrylic resin), and Z ₃ is the acoustic impedance of the inspection object 16. The acoustic impedances Z ₁ and Z ₂ are known intrinsic acoustic impedances determined according to the material for forming the ultrasonic transducer 13 and the ultrasonic transmission body 12, and are stored in advance in the memory 22 of the microcomputer 10. .

When the above expressions (1) and (2) are used, the voltage value ratio V ₂ / V ₁ is expressed by the following expression (3).

To summarize as following equation this equation (3) (4) to (7), the acoustic impedance _{Z 3} of the object to be inspected 16 is obtained.

  Further, the above equation (7) can be simplified as the following equation (8).

Here, A is a coefficient specific to the apparatus determined by the acoustic impedances Z ₁ and Z ₂ of the ultrasonic transducer 13 and the ultrasonic transmission body 12, and B is a voltage ratio of each reflected wave signal (next) (See Equation 9).

従って、測定した電圧値Ｖ_１，Ｖ_２と既知の音響インピーダンスＺ_１，Ｚ_２とを式（８）に代入することにより、被検査物１６の音響インピーダンスＺ_３を求めることができる。

Therefore, the acoustic impedance Z ₃ of the object to be inspected 16 can be obtained by substituting the measured voltage values V ₁ and V ₂ and the known acoustic impedances Z ₁ and Z ₂ into the equation (8).

Then, in this embodiment, a processing example in which the microcomputer 10 performs to measure an acoustic impedance Z ₃ of the object (living tissue) 16 will be described with reference to a flow chart in FIG. 5 is started when the measurement start button 18 of the operation panel 5 is operated by the user and a signal corresponding to the operation is input to the microcomputer 10.

First, the microcomputer 10 supplies a trigger signal to the transmitter 7 to output an excitation pulse P from the transmitter 7 (step 100). When this excitation pulse P is supplied to the ultrasonic transducer 13 of the ultrasonic sensor 3, the ultrasonic transducer 13 vibrates and the ultrasonic wave _So is irradiated from the vibrating surface 14. Then, the first reflected wave _St1 reflected on the surface of the biological tissue 16 after a predetermined time arrives at the ultrasonic transducer 13 and is converted into an electrical signal (reflected wave signal) by the ultrasonic transducer 13. Then, the reflected wave signal is extracted by the receiver 8, and a voltage value corresponding to the signal intensity of the reflected wave signal is A / D converted by the received voltage measuring device 9.

Next, the microcomputer 10 obtains a digital data converted by the received voltage measuring device 9 is stored as a voltage value V ₁ of the primary reflected wave S _t1 in the memory 22 (step 110).

Further, in the ultrasonic transmission body 12, the reflection is repeated between the vibration surface 14 of the ultrasonic transducer 13 and the tissue surface, and the secondary reflection in which the receiver 8 arrives at a time difference following the primary reflected wave _St1. The wave _St2 is received. A voltage value corresponding to the signal intensity of the reflected wave _{St 2} is A / D converted by the reception voltage measuring device 9.

Next, the microcomputer 10 obtains a digital data converted by the received voltage measuring device 9, and stores in the memory 22 as a voltage value V ₂ of the second reflected wave S _t2 (step 120).

Next, the microcomputer 10 reads out the acoustic impedance _{Z 2} of the acoustic impedance _{Z 1} and the ultrasound transmission member 12 of the ultrasonic transducer 13 from the memory 22, they acoustic impedance _Z 1, _{Z 2} and reflected waves _{S t1,} by performing the operation corresponding to the above formula (8) by using the voltage value _V 1, _{V 2} of S _t2, determining the acoustic impedance _{Z 3} of the living tissue 16 (step 130).

Next, the microcomputer 10 diagnoses the living tissue 16 based on the acoustic impedance _{Z 3} (step 140). Here, for example, collagen fibers is increased in cancerous biological tissue, because the cured compared to normal tissues, to diagnose whether tissue or not that cancerous based on the acoustic impedance Z ₃ calculated. The microcomputer 10 transmits the calculated biological tissue 16 an acoustic impedance Z ₃ and the data corresponding to the diagnostic result on the display 6, after displaying the diagnosis result and its acoustic impedance Z ₃ to the display 6 (step 150), the process is terminated.

  Therefore, according to the present embodiment, the following effects can be obtained.

(1) By using an acoustic impedance measuring apparatus 1 of this embodiment, it is not necessary to irradiate multiple times ultrasonic waves as in the prior art, is irradiated once ultrasonic waves S _o from the ultrasonic transducer 13, it can be obtained acoustic impedance Z ₃ of the living tissue 16. Further, it is possible to determine easily the acoustic impedance Z _3, since the processing circuit compared to the prior art can be simplified, it is possible to downsize the apparatus.

(2) The acoustic impedance measuring apparatus 1 according to the present embodiment uses the primary reflected wave _St1 and the secondary reflected wave _St2 that have a relatively large signal intensity and reach the ultrasonic transducer 13 early. since, it is possible to obtain an acoustic impedance Z ₃ of the living tissue 16 accurately and quickly.

(3) When the acoustic impedance measuring apparatus 1 of this embodiment, since the diagnostic result of the acoustic impedance Z ₃ and the living tissue 16 of the body tissue 16 is displayed on the display 6, easily check the properties of the living tissue 16 be able to.

(4) The acoustic impedance measuring apparatus 1 according to the present embodiment accommodates a receiver 8 as a signal intensity detecting means, a receiving voltage measuring instrument 9 and a microcomputer 10 as a computing means in a pen-like handpiece 2. it is, can have that handpiece 2 by hand to measure an acoustic impedance Z ₃ of the living tissue 16. If comprised in this way, the portable measuring apparatus excellent in operativity is realizable.

(5) In the case of the present embodiment, the ultrasonic transducer 13 has the same diameter as the ultrasonic transmission body 12, and the vibration surface 14 of the ultrasonic transducer 13 joined to the ultrasonic transmission body 12 is a plane. since it can be reliably reflected ultrasound S _o at the vibrating surface 14.

  In addition, you may change embodiment of this invention as follows.

In the above embodiment, to detect a secondary reflected wave S _t2 which then arrives with the primary reflected wave S _t1 which arrives first to the ultrasonic transducer 13, the voltage value of those of the reflected wave signals V _1, V ₂ on the basis, but were those seeking an acoustic impedance Z ₃ of the living tissue 16, but is not limited thereto. Specifically, the reflected waves after the tertiary reflected wave may be used in addition to the primary reflected wave _St1 and the secondary reflected wave _St2 . In other words, by extracting any two reflected waves out of the reflected wave may be configured to determine the acoustic impedance Z ₃ based on the signal strength of their reflected waves. However, when a reflected wave after the third-order reflected wave is used, the signal intensity becomes small, and the time until the ultrasonic transducer 13 arrives becomes long, so that signal detection becomes difficult. Therefore, it is preferable to determine the acoustic impedance Z ₃ based on as in the above embodiment the primary reflected wave S _t1 and secondary reflected waves S _t2.

  In the above embodiment, the acoustic impedance measuring device 1 having a pen shape is embodied, but is not limited thereto. For example, a measurement apparatus having a configuration in which an ultrasonic sensor 34 is connected to a box-shaped apparatus main body 32 via a signal cable 33, such as an acoustic impedance measurement apparatus 31 shown in FIG. The acoustic impedance measuring device 31 has a device main body 32 that fits in the palm of the hand, and is used as a portable measuring device. A device body 32 of the acoustic impedance measuring device 31 is provided with a display 35 and an operation panel 36. The ultrasonic sensor 34 includes an ultrasonic transmission body 12, an ultrasonic transducer 13, and a support member 39. Then, the connection terminal 37 of the signal cable 33 is inserted into the connector 38 provided in the apparatus main body 32, whereby the ultrasonic sensor 34 is connected to the processing circuit in the apparatus main body 32 via the signal cable 33. The processing circuit in the apparatus main body 32 includes a transmitter 7, a receiver 8, a received voltage measuring device 9, a microcomputer (microcomputer) 10, and the like as in the above embodiment.

In this acoustic impedance measuring device 31, an ultrasonic sensor 34 (connection terminal 37 of the signal cable 33) is detachably provided on a connector 38 of the device body 32, and the ultrasonic sensor 34 according to the type and size of the object to be inspected. Can be replaced. In addition, the device main body 32 can be provided with a display 35 having a relatively large screen size, and more information can be displayed on the display 35. Furthermore, since it is possible to move the ultrasonic sensor 34 at an arbitrary position, it is possible to quickly measure the acoustic impedance Z ₃ of a plurality of locations in the object to be inspected 16.

  In the above embodiment, the portable acoustic impedance measuring device 1 or 31 is embodied. However, other than this, the stationary acoustic impedance measuring device may be embodied as a stationary acoustic impedance measuring device.

In the acoustic impedance measuring devices 1 and 31 of the above-described embodiment, the single ultrasonic sensor 3 or 34 is provided. However, the measurement device is not limited to this and includes a plurality of ultrasonic sensors. May be. In this measuring device, for example, it is disposed a plurality of ultrasonic sensors in a matrix, measuring the acoustic impedance Z ₃ of the plurality of measurement points in the test object 16 using these ultrasonic sensors. In this way, it is possible to easily check the distribution of the acoustic impedance Z ₃ of the object to be inspected 16. Also in this case, it may be configured so as to be displayed on the display device the acoustic impedance image of the object 16 based on the acoustic impedance Z ₃ of each measurement point. By confirming this acoustic impedance image, the property of the inspection object 16 can be determined more accurately.

  In the above embodiment, acrylic resin is used as the ultrasonic transmission body 12 of the ultrasonic sensors 3 and 34, but other resin or metal material such as stainless steel may be used. Of course, it is not necessary to limit the ultrasonic transmission body 12 to a solid such as a resin or metal, and a liquid (such as water) capable of transmitting ultrasonic waves can also be used.

In the above embodiment, in which was intended to measure an acoustic impedance Z ₃ of the living tissue as an object to be inspected 16, as measured meat, fish, noodles, the acoustic impedance of the acoustic impedance and the liquid ingredients such as buckwheat Also good.

In the above embodiment, it performed tissue diagnosis based on the acoustic impedance Z ₃ of the measured object to be inspected 16, although the result of the diagnosis were those to be displayed on the display 6 is not limited thereto. For example, the acoustic impedance of meat and fish may be measured, freshness diagnosis may be performed based on the measured value, and the diagnosis result may be displayed on the display 6. In addition, based on the measured acoustic impedance, the amount of water such as udon or soba may be displayed, or the salt concentration of the liquid may be displayed on the display 6.

In the above embodiment, it obtains the acoustic impedance Z3 of the inspection object 16, but in which was intended to evaluate the characteristics of the object 16 based on the acoustic impedance Z _3, using parameters other than the acoustic impedance Z ₃ Thus, the characteristics of the inspection object 16 may be evaluated. It should be noted that parameters serving as elements for this characteristic evaluation are the signal strengths of the reflected waves S _t1 and S _t2 detected using the ultrasonic sensor 3 having the above-described configuration, and the signal strength and the ultrasonic transmission body 12. It is calculated based in the acoustic impedance Z ₁ of the acoustic impedance Z ₂ and the ultrasonic transducer 13.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiment described above are listed below.

  (1) The acoustic impedance measuring apparatus according to claim 6, wherein the signal intensity detecting means and the calculating means are accommodated in the handpiece.

  (2) The acoustic impedance measuring device according to claim 6, wherein the display means is provided on the handpiece.

  (3) The acoustic impedance measuring apparatus according to any one of claims 2 to 6, wherein the vibration surface is a flat surface.

  (4) In any one of claims 2 to 6, the signal intensity detecting means is configured to detect a gate circuit for detecting the primary reflected wave and the secondary reflected wave, and depending on a signal intensity of each reflected wave. And an A / D converter for A / D converting the measured voltage value.

  (5) The method according to claim 5, further comprising determination means for determining a property of the object to be inspected based on the acoustic impedance calculated by the calculation means and displaying the determination result on the display device. An acoustic impedance measuring device.

  (6) In any one of claims 2 to 5, the signal intensity detection means and the calculation means are provided in the apparatus main body, and the ultrasonic sensor having the ultrasonic transducer and the ultrasonic transmission body is connected to the apparatus main body. And an acoustic impedance measuring device detachably provided.

  (7) The acoustic impedance measuring device according to the technical idea (6), wherein the ultrasonic sensor is replaced according to a type of the inspection object.

The perspective view which shows the acoustic impedance measuring device of one Embodiment which actualized this invention. The block diagram which shows the electrical constitution of an acoustic impedance measuring apparatus. (A)-(c) is explanatory drawing which shows reflection of the ultrasonic wave in an ultrasonic sensor. The timing chart which shows the operation | movement waveform of an acoustic impedance measuring apparatus. The flowchart which shows the process example which a microcomputer performs. The perspective view which shows the acoustic impedance measuring apparatus of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,31 ... Acoustic impedance measuring apparatus 2 ... Handpiece 6,35 ... Display as display apparatus 8 ... Receiver which comprises signal strength detection means 9 ... Received voltage measuring device which comprises signal strength detection means 10 ... As calculation means Microcomputer 12 ... Ultrasonic transmitter 13 ... Ultrasonic vibrator 14 ... Vibrating surface 16 ... Biological tissue as inspection object

Claims (8)

An acoustic impedance measurement method for irradiating an inspection object with ultrasonic waves and measuring an acoustic impedance of the inspection object based on the obtained reflected wave,
An ultrasonic transducer having a known intrinsic acoustic impedance and vibration surface and the inspection object are arranged opposite to each other, and the ultrasonic transducer and the inspection object are disposed between the ultrasonic transducer and the inspection object. Interposing an ultrasonic transmission body having a known intrinsic acoustic impedance different from
Ultrasonic waves are irradiated from the ultrasonic transducer toward the object to be inspected, and the irradiated ultrasonic waves are multi-ordered on the surface of the object to be inspected by reflection action on the vibration surface of the ultrasonic vibrator. Detecting the signal intensity of an n-th order reflected wave (where n is a natural number) and an m-th order reflected wave (where m is a natural number greater than n) that is reflected in a timely manner and reaches the ultrasonic transducer with a time difference;
Based on the signal strength of the n-th order reflected wave, the signal strength of the m-th order reflected wave, the specific acoustic impedance of the ultrasonic transmitter, and the specific acoustic impedance of the ultrasonic transducer, the acoustic impedance of the object to be inspected is calculated. An acoustic impedance measuring method comprising the steps of: An acoustic impedance measuring device that irradiates an inspection object with ultrasonic waves and measures the acoustic impedance of the inspection object based on the obtained reflected wave,
A vibration surface having a known intrinsic acoustic impedance and capable of reflecting a reflected wave from the surface of the object to be inspected, converts an electric signal into vibration, generates an ultrasonic wave, and receives the reflected wave An ultrasonic transducer that converts it into an electrical signal,
The test object and the ultrasonic transducer have a known intrinsic acoustic impedance different from each other, and a proximal end is joined to the vibration surface of the ultrasonic transducer, while a distal end is directly with respect to the test object. An ultrasonic transmission body arranged to contact;
The nth-order reflected wave (where n is a natural number) and the mth-order reflected wave (where m is a natural number greater than n) that reaches the ultrasonic vibrator with a time difference due to the reflection effect on the vibration surface of the ultrasonic vibrator. Based on signal strength detection means for detecting their signal strength,
Based on the signal strength of the n-th order reflected wave, the signal strength of the m-th order reflected wave, the specific acoustic impedance of the ultrasonic transmitter, and the specific acoustic impedance of the ultrasonic transducer, the acoustic impedance of the object to be inspected is calculated. An acoustic impedance measuring apparatus comprising: an arithmetic means for performing the operation.   The n-order reflected wave is a primary reflected wave that first arrives at the ultrasonic transducer as a result of the ultrasonic wave emitted from the ultrasonic transducer being reflected by the surface of the inspection object, and the m-order reflected wave. The wave is a secondary reflected wave that arrives next to the primary reflected wave as a result of the primary reflected wave reflected by the vibration surface being reflected again by the surface of the inspection object. 2. The acoustic impedance measuring apparatus according to 2.   The signal intensity detecting means detects the primary reflected wave and the secondary reflected wave and outputs voltage values corresponding to the signal intensity to the calculating means, respectively, and the calculating means calculates the voltage based on the voltage values. The acoustic impedance measuring apparatus according to claim 3, wherein the acoustic impedance of the inspection object is calculated.   The acoustic impedance measuring apparatus according to claim 2, further comprising a display device that displays the acoustic impedance calculated by the computing unit.   The handpiece having a pen shape as a whole is further provided, and the ultrasonic transducer and the ultrasonic transmission body are arranged at a tip of the handpiece. The acoustic impedance measuring apparatus as described. A method of irradiating an inspection object with ultrasonic waves and evaluating the characteristics of the inspection object based on the obtained reflected wave,
An ultrasonic transducer having a known intrinsic acoustic impedance and vibration surface and the inspection object are arranged opposite to each other, and the ultrasonic transducer and the inspection object are disposed between the ultrasonic transducer and the inspection object. Interposing an ultrasonic transmission body having a known intrinsic acoustic impedance different from
Ultrasonic waves are irradiated from the ultrasonic transducer toward the object to be inspected, and the irradiated ultrasonic waves are multi-ordered on the surface of the object to be inspected by reflection action on the vibration surface of the ultrasonic vibrator. Detecting the signal intensity of an n-th order reflected wave (where n is a natural number) and an m-th order reflected wave (where m is a natural number greater than n) that is reflected in a timely manner and reaches the ultrasonic transducer with a time difference;
Based on the signal strength of the n-th order reflected wave, the signal strength of the m-th order reflected wave, the specific acoustic impedance of the ultrasonic transmission body, and the specific acoustic impedance of the ultrasonic transducer, for evaluating the characteristics of the inspection object An object characteristic evaluation method using ultrasonic waves, comprising: calculating a parameter as an element of An apparatus for irradiating an inspection object with ultrasonic waves and evaluating characteristics of the inspection object based on the obtained reflected wave,
A vibration surface having a known intrinsic acoustic impedance and capable of reflecting a reflected wave from the surface of the object to be inspected, converts an electric signal into vibration, generates an ultrasonic wave, and receives the reflected wave An ultrasonic transducer that converts it into an electrical signal,
The test object and the ultrasonic transducer have a known intrinsic acoustic impedance different from each other, and a proximal end is joined to the vibration surface of the ultrasonic transducer, while a distal end is directly with respect to the test object. An ultrasonic transmission body arranged to contact;
The nth-order reflected wave (where n is a natural number) and the mth-order reflected wave (where m is a natural number greater than n) that reaches the ultrasonic vibrator with a time difference due to the reflection effect on the vibration surface of the ultrasonic vibrator. Based on signal strength detection means for detecting their signal strength,
Based on the signal strength of the n-th order reflected wave, the signal strength of the m-th order reflected wave, the specific acoustic impedance of the ultrasonic transmission body, and the specific acoustic impedance of the ultrasonic transducer, for evaluating the characteristics of the inspection object An object characteristic evaluation apparatus using ultrasonic waves, comprising: an arithmetic means for calculating a parameter as an element of

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