WO2017098641A1

WO2017098641A1 - Ultrasonic transmission/reception apparatus and ultrasonic transmission/reception method

Info

Publication number: WO2017098641A1
Application number: PCT/JP2015/084699
Authority: WO
Inventors: 崇秀寺田; 川畑　健一; 悠史坪田; 文晶武; 一宏山中
Original assignee: 株式会社日立製作所
Priority date: 2015-12-10
Filing date: 2015-12-10
Publication date: 2017-06-15

Abstract

Provided is an ultrasonic transmission/reception apparatus capable of more precisely calculating the coordinates of the position of each transducer, and obtaining an image of a subject with high precision. In this ultrasonic transmission/reception apparatus, an electrical signal is inputted to a transmission unit, the transmission unit amplifies the electrical signal to generate a transmission signal and outputs the transmission signal to a transducer, and the transducer which has received the transmission signal converts the transmission signal to an ultrasonic signal and transmits the ultrasonic signal toward a specified space. The ultrasonic signal, which propagates through the specified space, is received by another transducer, and is converted to a reception signal which is an electrical signal, and a reception unit amplifies the reception signal and outputs the amplified reception signal. An image of a subject placed in the specified space is calculated on the basis of the amplified reception signal and one or more of a plurality of parameter values determined in advance. At this time, the parameter values include position information of the transducers and at least one of a signal response characteristic between the reception of the electrical signal by the transmission unit and the transmission of the ultrasonic signal by the transducer coupled to the transmission unit, and a signal response characteristic between the arrival of the ultrasonic signal at the transducer and the output of the amplified reception signal by the reception unit coupled to the transducer, and the ultrasonic signal is transmitted and received by the transmission unit and the reception unit, and the position information of the transducers and the signal response characteristics are calculated to perform calibration.

Description

Ultrasonic transmission / reception device and ultrasonic transmission / reception method

The present invention relates to an ultrasonic transmission / reception apparatus, and more particularly to a technique effective when applied to an apparatus for measuring an object using an ultrasonic signal.

Transmit ultrasonic waves toward the inside of the object, receive the ultrasonic waves that passed through the object through multiple paths, measure the propagation time from transmission to reception, etc., and determine the propagation time and propagation path length (

Patent Documents

1, 2 and the like propose a method for calculating a physical property value distribution (sound velocity distribution, stress distribution, attenuation amount distribution, etc.) of an object based on a propagation distance). Such a method is also referred to as an ultrasonic tomography method because a cross-sectional image of an object is obtained with respect to predetermined physical property values. Specifically, in the technique of Patent Document 1, ultrasonic waves are transmitted from the upper surface of the object toward the inside, and reflected by the back surface of the object and received by the upper surface of the object. Measure the propagation time. Using the propagation time and propagation path length measured for each path, the sound velocity distribution and stress distribution are obtained by matrix calculation or the like. On the other hand, in the technique of Patent Document 2, an object such as a breast is placed in a tank filled with liquid, ultrasonic waves are transmitted from a plurality of vibrators arranged in a ring shape so as to surround the tank, and a plurality of vibrations are transmitted. Receive at the child. Based on the ultrasonic wave propagation speed, propagation gain (intensity gain), and the like, an image showing the attenuation distribution in the object is calculated.

Patent Document 3 discloses the position of a transducer in a transducer array in which a plurality of transducers are arranged, such as a transducer array in which a plurality of transducers are arranged in a ring shape, which is used for detecting breast cancer or the like. A method for calibrating coordinates is disclosed. In this method, a signal delay time from transmission to reception is measured by transmitting and receiving ultrasonic waves with a pair of transducers in a state where no object is arranged, and based on the measurement result, the transducers are measured. The position coordinates are estimated and calibration is performed to compensate the position coordinates.

JP 2012-141230 A US Pat. No. 8,663,113 U.S. Pat. No. 8,532,951

As in

Patent Documents

1 and 2, in a method of calculating the distribution of physical property values (sound speed, stress, attenuation, etc.) of an object based on the propagation time, propagation path length, propagation gain, etc. of the ultrasonic wave in the object, In order to calculate physical property values with high accuracy, it is necessary to measure or calculate ultrasonic propagation time, propagation path length, and the like with high accuracy. For example, in order to obtain the sound speed, the propagation time and propagation distance (propagation path length) of the ultrasonic waves are required. The stress is obtained from the speed of sound. In order to obtain the attenuation, an ultrasonic wave propagation gain and a propagation distance are required.

In order to obtain the ultrasonic propagation path length and the like with high accuracy, the technique described in Patent Document 3 calculates the inter-vibrator distance from the signal delay time from transmission to reception between the transducer pairs, and The position coordinates are estimated and the position coordinates are calibrated. However, according to the experiments and simulations of the inventors, even if ultrasonic waves are transmitted and received using the transducer array calibrated according to Patent Document 3, a substance different from that at the time of calibration is arranged in the ultrasonic wave propagation space. In this case, it was found that the signal delay time could not be calculated with high accuracy. Therefore, if an object is placed in the ultrasonic propagation space and actually measured, the signal delay time cannot be calculated with high accuracy.

An object of the present invention is to provide an ultrasonic transmission / reception apparatus capable of calculating the position coordinates of each transducer with higher accuracy and obtaining an object image with higher accuracy.

In order to solve the above problems, the present invention provides a transducer array including a plurality of transducers, a transmission unit connected to at least one transducer among the plurality of transducers, and at least one of the plurality of transducers. Provided is an ultrasonic transmission / reception apparatus having a reception unit, a calculation unit, and a control unit connected to two other transducers. At this time, the transmission unit receives an electrical signal from the control unit, amplifies the electrical signal, generates a transmission signal, outputs the transmission signal to the connected transducer, and the transducer that receives the transmission signal transmits the transmission signal. It converts into an ultrasonic signal and transmits toward a predetermined space. The other transducers that have received the ultrasonic signal propagating in the predetermined space convert the ultrasonic signal into a received signal that is an electrical signal, and the receiving unit amplifies the received signal and outputs the amplified received signal. . The calculation unit calculates an image of the object arranged in a predetermined space based on the amplified received signal and one or more of a plurality of parameter values obtained in advance. The parameter value includes a signal response characteristic in at least one of the transmitter and the transducer connected to the transmitter, and between the transducer and the receiver connected to the transducer, and position information of the transducer. ,including. The control unit has a calibration mode for adjusting the parameter value. In the calibration mode, an ultrasonic signal is transmitted and received by operating the transmission unit and the reception unit, and signal response characteristics and position information of the transducer are calculated.

According to the present invention, errors in position coordinates and signal response characteristics can be compensated, respectively, so that an image of an object can be obtained with high accuracy.

(A) It is a block diagram which shows the structure of the ultrasonic transmitter-receiver of 1st embodiment, (b) It is explanatory drawing which shows the relationship between a signal response characteristic, an ultrasonic propagation characteristic, and a signal propagation characteristic. It is a block diagram which shows the structural example of the ultrasonic transmitter / receiver by 2nd embodiment. FIG. 6A is a plan view of an transducer array of an ultrasonic transmission / reception apparatus according to a second embodiment, and FIGS. 5B to 5G are diagrams illustrating examples of information stored in a storage unit. (A)-(f) It is explanatory drawing which shows the other example of a shape of the transducer | vibrator array of the ultrasonic transmitter-receiver by 2nd embodiment. It is a signal waveform diagram explaining the operation example of the ultrasonic transmission / reception apparatus by 2nd embodiment, (a) When the liquid of uniform sound speed is arrange | positioned in the space 30, (b) The measuring object is arrange | positioned. Each case is shown. It is a sequence diagram explaining the operation example of the calibration mode of the ultrasonic transmitter-receiver by 2nd embodiment. It is a flowchart which shows operation | movement of the control part of the ultrasonic transmitter / receiver by 2nd embodiment. It is a flowchart which shows operation | movement of the calibration mode of the ultrasonic transmitter-receiver by (a) and (b) 2nd embodiment. It is a flowchart which shows operation | movement of the calibration mode of the ultrasonic transmitter / receiver by 2nd embodiment. It is a sequence diagram explaining the operation example of the measurement mode of the ultrasonic transmitter-receiver by 2nd embodiment. (A) And (b) It is a flowchart which shows operation | movement of the measurement mode of the ultrasonic transmitter-receiver by 2nd embodiment. Explanatory drawing which shows the example of a display screen of the calibration result in the calibration mode of FIG. 10 is a flowchart for explaining the operation of a modification of the calibration mode of the ultrasonic transmission / reception apparatus according to the second embodiment. 10 is a flowchart for explaining the operation of a modification of the calibration mode of the ultrasonic transmission / reception apparatus according to the second embodiment. (A) It is a flowchart explaining operation | movement of the modification of the calibration mode of the ultrasonic transmitter / receiver by 2nd embodiment, (b) It is a graph which shows the change of the calculated position and signal response time. (A) It is a flowchart explaining operation | movement of the modification of the calibration mode of the ultrasonic transmitter / receiver by 2nd embodiment, (b) It is a flowchart explaining the modification of measurement mode. Explanatory drawing which shows the example of a display screen of the calibration result in the calibration mode of Fig.16 (a). FIG. 7A is a plan view of an transducer array of an ultrasonic transmission / reception apparatus according to a third embodiment, and FIGS. 5B to 5G are diagrams illustrating examples of information stored in storage units. (A) And (b) It is a flowchart which shows operation | movement of the calibration mode of the ultrasonic transmitter-receiver by 3rd embodiment. Explanatory drawing which shows the example of a display screen of the calibration result in the calibration mode of Fig.19 (a). It is a flowchart which shows operation | movement of the modification of the calibration mode of the ultrasonic transmitter / receiver by 3rd embodiment. (A) It is a flowchart explaining the operation | movement of the modification of the calibration mode of the ultrasonic transmitter / receiver by 3rd embodiment, (b) It is a graph which shows the change of conversion gain. It is a flowchart which shows operation | movement of the modification of the calibration mode of the ultrasonic transmitter / receiver by 3rd embodiment. (A) It is a flowchart explaining the operation | movement of the modification of the calibration mode of the ultrasonic transmitter / receiver by 3rd embodiment, (b) It is a graph which shows the change of the position of a transducer | vibrator, and a signal conversion gain. It is a flowchart which shows operation | movement of the modification of the calibration mode of the ultrasonic transmitter / receiver by 3rd embodiment. FIG. 26 is an explanatory diagram illustrating a display screen example of a calibration result in the calibration mode of FIG. 25.

In order to accurately calculate the distribution of physical property values (sound speed, stress, attenuation, etc.) of an object, it is necessary to accurately measure or calculate the propagation time, propagation path length, etc. of the ultrasonic wave in the object. . Therefore, it is desirable to measure the signal delay time from transmission to reception of the ultrasonic wave, estimate the position coordinate of the transducer based on the measurement result, and compensate the position coordinate. Inventors of the present invention, in the signal delay time from the transmission of ultrasonic waves to the reception thereof, in addition to the ultrasonic wave propagation time between the ultrasonic wave transmitting transducer and the receiving transducer, an ultrasonic wave transmitting transducer The signal response time between the transmitter that outputs the transmission signal that is an electrical signal and the transducer, and the signal response time between the transducer that receives the ultrasonic wave and the receiver that receives the received signal are errors. I found it included. The signal response time between the transmission unit and the vibrator is such that the transmission unit receives an input of an electrical signal to be transmitted from the control unit, and then the transmission unit amplifies the electrical signal to generate a transmission signal. This is the time from when the transducer including the structure of FIG. The signal response time between the receiver and the transducer is converted into a received signal that is an electrical signal after the ultrasonic wave reaches the transducer including the matching layer and acoustic lens, and the receiver amplifies the received signal. It is the time until output.

When the position coordinate of the transducer is compensated using the signal delay time between the transmission unit and the reception unit as in the prior art (for example, Patent Document 3), the compensated position coordinate is a signal response to the signal delay time. It contains an error due to the inclusion of time. In this case, if the propagation characteristic of the propagation space of the ultrasonic signal is the same as that at the time of calibration (that is, if the measurement target object (object) does not exist in the propagation space), the transmitted signal is transmitted and received Since the timing received by the unit coincides with a desired value, at first glance, it seems that the error has been removed from the measurement result. However, in the actual measurement, since the object is arranged, it is impossible to accurately calculate the propagation time and propagation path of the ultrasonic wave. For this reason, it is not possible to obtain an accurate physical property value such as sound velocity or attenuation.

Also, if the transducer position coordinates include an error in signal response time (an error that is not a function of position coordinates), the signal delay time between multiple sets of transmitters and receivers is measured, and each signal delay time When the position coordinates of the transducer are obtained from the above, they become different position coordinates. Therefore, for example, if one position coordinate is obtained by averaging a plurality of position coordinates, an error occurs. It can also be considered that the position coordinates are individually given to each combination of the transmission unit and the reception unit, and the vibrator is moved in a pseudo manner according to the combination of the transmission and reception units. However, in this case, since the relationship between the position coordinates defined for each combination of transmitting and receiving units is unknown, matrix calculation for obtaining physical property values such as sound speed and attenuation amount to be measured cannot be performed.

Also, when transmitting ultrasonic waves from multiple transducers simultaneously to form a composite wave such as a plane wave, grasp the signal response time between the transmitter and transducer and the signal response time between the transducer and receiver. It is important to. This is because if the timing of the ultrasonic signal radiated from each transducer to the space deviates from the desired timing, the shape of the synthesized wave will collapse. In other words, if the error of the signal response time is included in the position coordinates to compensate, the synthesized wave of the ultrasonic signal is broken, and the accurate shape of the measurement target and the physical property values such as the sound speed and attenuation cannot be obtained.

Therefore, in order to accurately calculate the distribution of physical property values (sound speed, stress, attenuation, etc.) of the target object, the error of the signal response time included in the signal delay time from transmission to reception is removed, and the transducer The inventors have found that the position coordinates of must be calculated.

Similarly, when obtaining the attenuation amount or the like as the physical property value of the target object, it is necessary to obtain the signal gain from the transmission unit to the reception unit (for example, the intensity ratio between the transmission signal and the reception signal). In addition to the ultrasonic propagation gain between the transducer that transmits the ultrasonic signal and the transducer that receives the signal, the signal conversion gain between the transmitter and the transducer that outputs the transmission signal to the transducer, and The inventors have found that a signal conversion gain between a transducer that receives ultrasonic waves and a receiving unit that amplifies the received signal is included as an error. The signal conversion gain between the transmission unit and the transducer is a signal gain between the electric signal received by the transmission unit from the control unit and the ultrasonic wave radiated from the transducer. The signal conversion gain between the receiving unit and the transducer is a signal gain between the ultrasonic signal reaching the transducer and the received signal after amplification by the receiving unit.

If the signal gain from the transmission unit to the reception unit includes an error in the signal conversion gain, the physical property value of the object cannot be calculated with high accuracy as in the case of the signal delay time.

Therefore, in order to accurately calculate the distribution of physical property values (attenuation amount, etc.) of the target object, the error of the signal conversion gain included in the signal gain from transmission to reception is removed, and the position coordinates of the transducer are calculated. Must.

<< First Embodiment >>
Therefore, in the first embodiment of the present invention, the following ultrasonic transmission / reception apparatus is provided. That is, as shown in FIG. 1, the ultrasonic transmitting / receiving apparatus according to the first embodiment includes a transducer array 2 including a plurality of transducers 1a to 1d and at least one transducer among the plurality of transducers 1a to 1d. The transmission unit 6 connected to 1a, the reception unit 7 connected to at least one other transducer 1d among the plurality of transducers 1a to 1d, the arithmetic unit 20, and the control unit 4. The transmission unit 6 receives the electric signal S1 to be transmitted from the control unit 4, amplifies it to generate a transmission signal S11, and outputs it to the connected transducer 1a. The transducer 1a that has received the transmission signal S11 converts the transmission signal S11 into an ultrasonic signal S21 and transmits the ultrasonic signal S21 toward a predetermined space (propagation space) 30.

The other transducer 1d to which the ultrasonic signal S21 that has propagated through the predetermined space 30 arrives converts the ultrasonic signal S21 into a reception signal S31 that is an electrical signal. The receiving unit 7 amplifies the received signal S31 from the other transducer 1d and outputs the amplified received signal S41.

The calculation unit 20 calculates an image of the object placed in the predetermined space 30 based on the amplified received signal S41 and one or more of a plurality of parameter values obtained in advance. The plurality of parameter values are stored in the parameter storage unit 19. In the present embodiment, the parameter value is a signal response characteristic between the time when the transmission unit 6 receives the electrical signal S1 and the time when the transducer 1a connected to the transmission unit 6 transmits the ultrasonic signal S21. At least one of signal response characteristics from when the ultrasonic signal S21 arrives at the transducer 1d to when the receiving unit 7 connected to the other transducer 1d outputs the received signal S41 after amplification, and the

transducer

1a, 1d position information.

The control unit 4 has a calibration mode 4a for adjusting a parameter value used by the calculation unit 20 for calculation. In the calibration mode 4a, the control unit 4 operates the transmission unit 6 and the reception unit 7 to transmit / receive the ultrasonic signal S21, and obtains the signal response characteristics R1 and R2 and the position information of the

transducers

1a and 1d. calculate.

In this manner, the signal response characteristics R1 (signal response time R1t · signal conversion gain R1A), R2 (signal response time R2t · signal conversion gain R2A) and the positional information of the

transducers

1a and 1d are calculated and calibration is performed. Thus, the signal response characteristics R1 and R2 between the transmission unit 6 and the transducer 1a and between the other transducer 1d and the reception unit 7 are amplified by the reception unit 7 after the transmission unit 6 receives the electric signal S1. It is possible to reduce errors caused by being included in the characteristics (signal propagation characteristics PR (signal delay time PRt · signal gain PRA)) until the subsequent reception signal S41 is output. Therefore, it is possible to calculate the position information of the

transducers

1a and 1d and the ultrasonic propagation characteristics P1 (ultrasonic propagation time P1t and ultrasonic propagation gain P1A) between the

transducers

1a and 1d with higher accuracy. Therefore, the parameter value used by the calculation unit 20 for calculating the image of the object can be adjusted with high accuracy, and the accuracy of the image of the object can be improved.

For example, in the calibration mode 4a, the control unit 4 performs the signal delay time PRt from the timing T1 when the transmission unit 6 receives the electrical signal S1 from the control unit 4 to the timing T4 when the reception unit 7 outputs the amplified reception signal S41. Is calculated (FIG. 1B). Based on the calculated signal delay time PRt, the control unit 4 transmits, as signal response characteristics R1 and R2, the timing T2 at which the ultrasonic signal S21 is transmitted from the transducer 1a from the timing T1 when the transmission unit 6 receives the electrical signal S1. Signal transmission time until transmission (R1t = T2-T1) and from timing T3 when the ultrasonic signal S21 is received by the transducer 1d to timing T4 when the amplified reception signal S41 is output from the receiving unit 7 At least one of the signal response times (R2t = T4-T3) at the time of reception is calculated. Then, the control unit 4 calculates the position information of each

transducer

1a, 1d and the ultrasonic wave propagation time P1t between the

transducers

1a, 1d with higher accuracy.

Further, for example, in the calibration mode 4a, the control unit 4 has an intensity ratio A4 between the intensity A1 of the electrical signal S1 received from the control unit 4 by the transmission unit 6 and the intensity A4 of the amplified reception signal S41 output from the reception unit 7. A signal gain PRA that is / A1 may be obtained. Based on the intensity ratio A4 / A1, the control unit 4 converts the signal during transmission between the intensity A1 of the electrical signal S1 and the intensity S2 of the ultrasonic signal S21 transmitted by the vibrator 1a as the signal response characteristic R1. Gain (R1A = A2 / A1) and signal conversion gain during reception (R2A = A4 / A3) between the intensity A3 of the ultrasonic signal S21 reaching the other transducer 1d and the intensity A4 of the amplified received signal S41 ) Can be calculated. Then, the control unit 4 calculates the position information of the

transducers

1a and 1d and the ultrasonic wave propagation gain P1A between the

transducers

1a and 1d with higher accuracy.

The control unit 4 adjusts the parameter value in the parameter storage unit 19 used by the calculation unit 20 for calculating the image, based on the signal response characteristics R1 and R2 calculated in the calibration mode 4a and the position information of the

transducers

1a and 1d. Is possible.

Further, the control unit 4 has a measurement mode 4b that transmits an ultrasonic signal to the object and causes the calculation unit 20 to calculate an image. The signal response characteristics R1 and R2 calculated in the calibration mode 4a, and It is also possible to adjust at least one of the transmission condition of the transmission signal S11 of the transmission unit 6 and the reception condition of the reception signal S31 of the reception unit 7 in the measurement mode 4b by the position information of the

transducers

1a and 1d.

Further, when the transducer array 2 includes a drive unit (not shown in FIG. 1A) for displacing the position coordinates of the

transducers

1a and 1d, the control unit 4 calculates in the calibration mode 4a. It is also possible to adjust the position coordinates of the

vibrators

1a and 1d by operating the drive unit according to the position information.

Thereby, the calculation unit 20 is connected to the transducer 1a to which the transmission unit 6 is connected and the reception unit 7 based on the amplified reception signal S41 received from the reception unit 7 and the parameter value of the parameter storage unit 19. The ultrasonic propagation characteristic P1 of the ultrasonic signal S21 between the transducer 1d can be obtained by reducing errors due to the signal response characteristics R1 and R2. Based on the ultrasonic propagation characteristic P1 of the obtained ultrasonic signal S21, an image showing the distribution of physical property values (for example, sound speed, stress, attenuation, etc.) of the object can be accurately calculated. Thereby, ultrasonic tomography is realizable.

When generating an image of a physical property value of an object, the transducer 1d connected to the receiving unit 7 is arranged at a position where the direct wave of the ultrasonic signal S21 transmitted by the transducer 1a connected to the transmitting unit 6 reaches. It is desirable that For example, the transducer array 2 can be arranged so as to surround a predetermined propagation space 30 as shown in FIG.

Further, it is possible to adopt a configuration in which the transmitter 6 and the receiver 7 are connected to the plurality of vibrators 1a to 1d, respectively. Accordingly, the ultrasonic signal S21 can be transmitted from any one or more transducers of the plurality of transducers 1a to 1d and can be received by any one or more transducers. It is possible to receive the object by passing or reflecting it through the path. Therefore, it is possible to easily calculate the image of the object.

Thus, according to the first embodiment, the position coordinates of the transducer can be calculated while suppressing errors in the signal response characteristics R1 and R2 included in the signal propagation characteristics PR from transmission to reception. The distribution of physical property values (attenuation amount, etc.) of the object can be calculated with high accuracy.

In the following second and third embodiments, the ultrasonic transmission / reception apparatus will be described more specifically.

<< Second Embodiment >>
An ultrasonic transmission / reception apparatus according to the second embodiment will be described.

The ultrasonic transmission / reception apparatus according to the second embodiment is configured to obtain signal response times R1t and R2t as signal response characteristics R1 and R2.

FIG. 2 is a block diagram showing a configuration example of an ultrasonic transmission / reception apparatus including a plurality of transducers 1 according to the second embodiment. In FIG. 2, the same reference numerals are given to the same configurations as those in FIG. 1A of the first embodiment.

2 will be described below. The ultrasonic transmission / reception device 5 transmits and receives an ultrasonic wave array S2 (see FIGS. 1A and 1B) connected to the vibrator 1 and the vibrator array 2 including a plurality of vibrators 1 (1a to 1d, etc.). A transmission / reception unit 3, a control unit 4 that controls the transmission / reception unit 3, a storage unit 9, a display unit 10, and an operation unit (I / F) 40. The transducer array 2 is disposed so as to surround a space 30 in which ultrasonic waves are propagated. A parameter storage unit 19 is disposed in the storage unit 9.

The transmission / reception unit 3 includes a transmission unit 6, a reception unit 7, and a transmission / reception switch (T / R SW) 8 for switching between transmission and reception. One transmission / reception unit 3 is connected to one transducer 1, and each transmission / reception unit 3 can independently transmit and receive an ultrasonic signal. The control unit 4 can output different signals such as control signals S51 and S52 to the transmission / reception units 3 to perform different controls. For example, the control unit 4 can perform a transmission operation by the transmission / reception unit 3 to which the control signal S51 instructing transmission is input, and can perform a reception operation by the transmission / reception unit 3 to which the control signal S52 instructing reception is input.

The transmission unit 6 includes, for example, an amplifier, amplifies the electric signal S1 input from the control unit 4 to a desired intensity, generates a transmission signal S11, and outputs the transmission signal S11 to the vibrator 1. The vibrator 1 includes a structure such as a matching layer and an acoustic lens, and converts (transmits) the transmission signal S11 received from the transmission unit 6 into ultrasonic waves. The sound pressure of the ultrasonic signal radiated from the vibrator 1 changes according to the signal intensity of the transmission signal S11 delivered to the vibrator 1. The signal strength of the transmission signal S11 generated by the transmission unit 6 is set by the control signal S51.

The signal response time R1t in the transmission operation of the transmission / reception unit 3 is the time from the timing T1 when the electric signal S1 is input to the transmission unit 6 from the control unit 4 to the timing (T2) when the ultrasonic signal S21 is output from the transducer 1 (T2-T1). It is also possible to arrange a function (for example, a signal delay circuit) for adjusting the signal response time in the transmission operation in the transmission / reception unit 3, and set the desired signal response time R1t by the control signal S51.

The emitted ultrasonic signal S21 passes through the propagation space 30 and reaches another transducer 1. The vibrator 1 includes structures such as a matching layer and an acoustic lens, and converts the arrived ultrasonic signal S21 into a reception signal S31 that is an electric signal and outputs the received signal S31. The receiving unit 7 includes, for example, an amplifier, a filter, and an analog-digital converter, amplifies the electrical signal (received signal S31) output from the vibrator 1, and reduces noise outside a desired frequency band. Then, the signal is quantized and an amplified reception signal S41 is generated and output to the control unit 4. The gain of the amplifier of the receiving unit 7 and the filter constant are set by the control signal S52. The intensity of the electrical signal of the reception signal S31 output from the vibrator 1 changes according to the sound pressure of the ultrasonic signal S21 received by the vibrator 1. The signal response time R2t in the reception operation of the transmission / reception unit 3 is a time (T4-T3) from timing T3 when the ultrasonic signal S21 is input to the transducer 1 to timing T4 when the amplified reception signal S41 is output from the reception unit 7. ). The transmitter / receiver 3 may be provided with a function (for example, a signal delay circuit) for adjusting a signal response time in the reception operation, and may be set to a desired signal response time R2t by the control signal S52.

The transmission / reception switch 8 disconnects the connection between the receiving unit 7 and the vibrator 1 during the transmission operation and short-circuits the reception operation. This prevents the receiving unit 7 from being destroyed by the high-voltage transmission signal S11 output from the transmitting unit 6 to the vibrator 1 during the transmission operation.

The control unit 4 includes a calibration mode 4a, a measurement mode 4b, and a calculation unit 20. The control unit 4 has a CPU (Central Processing Unit) and a memory in which a program is stored in advance, and the CPU reads and executes the program, whereby the functions of the calibration mode 4a, the measurement mode 4b, and the calculation unit 20 are performed. Are realized by software. Note that the control unit 4 is not limited to a configuration that realizes the function by software, and a part or all of the control unit 4 may be a custom IC (Integrated Circuit) such as ASIC (Application Specific Integrated Circuit) or FPGA. It can also be configured by hardware such as a programmable IC such as (Field-Programmable Gate Array).

In the calibration mode 4 a and the measurement mode 4 b, the control unit 4 controls the transmission / reception unit 3 according to a predetermined procedure, and transmits an ultrasonic signal to the measurement target arranged in the space 30 surrounded by the transducer array 2. S21 is transmitted and the ultrasonic signal 21 that has passed through the space 30 is received. In the calibration mode 4a, the control unit 4 calculates one or more parameter values using a received signal or the like, and adjusts (calibrates) the parameter values stored in the parameter storage unit 19. On the other hand, using the received signal obtained in the measurement mode 4b, the computing unit 20 computes the obtained received signal S41 after amplification using the parameter value stored in the parameter storage unit 19, thereby obtaining the space 30. And the physical property values such as the speed of sound and attenuation of the ultrasonic signal S21 are measured. For example, the ultrasonic signal S21 transmitted from a certain transducer 1 passes (propagates) through the space 30 through a predetermined path while being transmitted through the measurement target or reflected on the surface of the measurement target and the end face of the internal structure. And received by another vibrator 1. Using the parameter values stored in the parameter storage unit 19, the calculation unit 20 can calculate the time (ultrasonic propagation time) that the ultrasonic signal S <b> 21 propagates through the space 30 and obtain the sound speed of the measurement target. . The ultrasonic propagation time is a time (T3-T2) from when an ultrasonic signal is output from one transducer 1 to when an ultrasonic signal is input to another transducer 1. The sound speed can be obtained from the ultrasonic propagation time and the distance between the two transducers 1. The sound speed distribution of the measurement target can be calculated by obtaining the sound speed for each of a plurality of different propagation paths and performing matrix calculation or the like. Also, other physical property values can be calculated based on the speed of sound.

The storage unit 9 stores information such as settings related to the transmission / reception operation of each transmission / reception unit 3 and the signal waveform of the electric signal S1 output to the transmission unit 6. The parameter storage unit 19 of the storage unit 9 stores values such as the signal response times R1t and R2t of each transmitter / receiver 3 obtained in advance and the position coordinates of each transducer 1 in the transducer array 2. In addition, the storage unit 9 also appropriately stores measurement results such as the waveform of the amplified received signal S41, the signal delay time (PRt = T4-T1), the ultrasonic wave propagation time P1t, the shape of the measurement target, the sound speed, and the amount of attenuation. .

The display unit 10 displays the measurement result (image) of the measurement target, displays the position coordinates of each transducer 1 in the transducer array 2, the signal response times R1t and R2t of each transmission / reception unit 3, and the like. In accordance with this, the operator gives an instruction to the control unit 4 or exchanges information with other devices through the operation unit 40.

FIG. 3A is an example of the arrangement of the transducers 1 in the transducer array 2. FIGS. 3B to 3G are tables showing examples of information stored in the parameter storage unit 19 of the storage unit 9. As shown in FIG. 3A, the transducer array 2 has a structure in which the transducers 1 are arranged in a ring shape on a plane expressed by the orthogonal x-axis and y-axis.

At this time, the position coordinates of the

transducers

1a, 1b, and 1c are stored in the parameter storage unit 19 as shown in the table of FIG. Further, the transmitting / receiving unit 3 connected to the

vibrators

1a, 1b, 1c is represented by 3a, 3b, 3c, respectively, and the transmitting unit 6 and the receiving unit 7 in the transmitting / receiving unit 3 are respectively represented by 6a, 6b, 6c and 7a, 7b, 7c, the signal response time R1t between the

transducers

1a, 1b, 1c and the transmission unit 6 of the transmission / reception units 3a, 3b, 3c, and the

transducers

1a, 1b, 1c and the transmission / reception units 3a, 3b, 3c. The signal response time R2t with the receiving unit 7 is stored in the parameter storage unit 19 as in the table of FIG. For example, the signal response time R1t in the transmission operation of the transmission / reception unit 3a is 0.1 μs, and the signal response time R2t in the reception operation is 0.3 μs.

The parameter storage unit 19 also stores the signal delay time PRt between the transmission / reception units 3 when the space 30 is filled with a predetermined substance as shown in the table of FIG. In FIG. 3D, the transmission unit 6 and the reception unit 7 in the transmission / reception units 3a, 3b, and 3c connected to the

vibrators

1a, 1b, and 1c are represented by 6a, 6b, 6c, and 7a, 7b, and 7c, respectively. For example, when the space 30 surrounded by the transducer array 2 is filled with water having a sound velocity of 1500 m / s, the transmission / reception unit starts from the timing T1 when the electrical signal S1 is input from the control unit 4 to the transmission unit 6a in the transmission / reception unit 3a. The signal delay time PRt until the timing T4 when the amplified reception signal S41 is output from the reception unit 7 in 3b is 94.68 μs. This is because the ultrasonic wave propagation time P1t obtained using the distance between the transducers obtained from the position coordinates of the

transducers

1a and 1b and the sound speed, the signal response time R1t in the transmission operation of the transmission / reception unit 3a, and the transmission / reception unit 3b. Is the sum of the signal response time R2t in the receiving operation.

FIG. 3E shows a table of position coordinates stored in the parameter storage unit 19 when the position coordinates of the vibrator 1b are shifted by 0.2 mm toward the vibrator 1a along the x axis. Such positional coordinate deviation (error) is caused by manufacturing variations of the transducer 1b, assembly errors of the transducer array 2, and the like. FIG. 3 (f) is an example of a table representing signal response times R1t and R2t when the signal response time R1t in the transmission operation of the transmission / reception unit 3c is 0.1 μs later than the table of FIG. 3 (c). . Such an error in the signal response time R1t is caused by deterioration of each component over time or change in usage environment, manufacturing variation of the transducer 1c, manufacturing variation of the transmission unit 6c, and manufacturing of a cable connecting the transducer 1c and the transmission unit 6c. This may occur due to variations, timing errors of the clock signal input from the control unit 4 to the transmission unit 6c, and the like. In the case of the position coordinates and the signal response times R1t and R2t shown in FIGS. 3E and 3F, the signal delay time PRt is as shown in the table shown in FIG. The difference between the tables in FIGS. 3D and 3G is due to the error in the position coordinates of the transducer 1b and the error in the signal response time R1t in the transmission operation of the transmission / reception unit 3c.

The position coordinates of the vibrator 1 are not limited to being expressed by the orthogonal x-axis and y-axis, but may be polar coordinates expressed by a distance and an angle from the origin, coordinates in a three-dimensional space, or any other coordinate system. . Further, the above-described parameter values stored in the parameter storage unit 19 are not limited to being stored in the form of a table, but may be stored in other formats.

FIG. 4 is a diagram showing another shape example of the transducer array 2 of the ultrasonic transmission / reception device 5 according to the second embodiment. The arrangement of the transducers 1 in the transducer array 2 is not limited to a circle as shown in FIG. The transducer array 2 receives, by another transducer 1, a signal in which the ultrasonic signal S 21 transmitted from a certain transducer 1 is transmitted through the measurement target or reflected from the surface of the measurement target and the end face of the internal structure. Any shape can be used. That is, as long as there is no obstacle in the space 30, it is only necessary that one vibrator 1 and another vibrator 1 are in a line-of-sight state.

The transducer array 2 may be oval, polygonal (FIG. 4A), or partially recessed (FIG. 4B). The transducer array 2 is not limited to a closed loop shape, and may be a shape in which a part of the transducer array 2 is open (FIG. 3C). Further, the transducer array 2 may have a shape including a plurality of transducer sub-arrays 11 (FIGS. 3D and 3E). The transducer subarrays 11 are not necessarily separated from each other. For example, the shape of FIG. 3A may be configured by combining a plurality of transducer subarrays 11. The shape of the transducer array 2 is not limited to the shape in which the transducers 1 are arranged on a two-dimensional plane, and may be a shape in which the transducers 1 are arranged in three dimensions such as a cylindrical shape or a hemisphere (FIG. 3). (F)).

It is also possible to adopt a structure in which a driving device such as a motor is connected to the vibrators of these vibrator arrays 2 and the vibrator is displaced by the driving device.

FIGS. 5A and 5B are signal waveform diagrams for explaining an operation example of the ultrasonic transmission / reception apparatus 5 according to the second embodiment. FIG. 5A shows an example in which the space 30 inside the transducer array 2 is viewed with a predetermined substance such as water and the sound velocity distribution is constant, and is used in the calibration mode 4a. The ultrasonic signal S21 is transmitted from the vibrator 1a at the timing T2, and the ultrasonic signal S21 is received by the

vibrators

1b, 1c, and 1d. Timings T3b, T3c, and T3d at which the ultrasonic signals S21 are received by the

transducers

1b, 1c, and 1d depend on the distance between the transducer 1a and the

transducers

1b, 1c, and 1d. Therefore, the transducer 1b closest to the transducer 1a first receives the ultrasonic signal S21, then the transducer 1c receives, and finally the transducer 1d receives.

FIG. 5B is an example in which the measurement object A composed of a substance having a slow sound speed is arranged in the space 30 in the state of FIG. 5A, and is a state when measurement is performed in the measurement mode. The substance constituting the measurement object A has an acoustic impedance different from that of the surrounding water or the like. In this case, part of the energy of the ultrasonic signal S21 transmitted from the transducer 1a is reflected on the surface of the measurement target A, or the signal is absorbed or scattered inside the measurement target A. In addition, the speed of sound is reduced inside the measurement object A. The

vibrators

1c and 1d receive the transmitted wave that has passed through the measurement A. The signal intensity of the transmitted wave is reduced due to reflection, absorption, and scattering, and the reception timings T3c and T3d are later than in the case of FIG. 5A (indicated by a dotted line). On the other hand, in the transducer 1b, since the ultrasonic signal S21 transmitted from the transducer 1a arrives without passing through the substance A, the transmitted wave is received at the same timing T3b-1 as in FIG. In addition, the reflected wave reflected from the surface of the measuring object A is received at a timing T3b-2 that is delayed by the propagation distance. Further, also in the vibrator 1a, the reflected wave reflected from the surface of the measurement target A is received at a timing T3a corresponding to the distance between the vibrator 1a and the measurement target A. Thus, since the reception timing and signal intensity of the transmitted wave and the reflected wave are determined by the positional relationship between each transducer 1 and the measurement target A, the calculation unit 20 includes the transducer 1 that performs the transmission operation and the transducer that performs the reception operation. By performing a known tomography method that performs matrix calculation using various combinations of 1, the shape of the measurement target A and physical property values such as sound speed and attenuation can be acquired. The calculation method of the calculation unit 20 will be described in detail later.

The operation of the control unit 4 will be specifically described with reference to FIGS. FIG. 6 is a sequence diagram for explaining the operation of each part in the calibration mode 4a. FIG. 7 is a flowchart showing the overall flow of the operation of the control unit 4. FIGS. 8A, 8B, and 9 are flowcharts showing detailed operations of the control unit 7 in the calibration mode 4a. FIG. 10 is a sequence diagram for explaining the operation of each part in the measurement mode 4b. FIGS. 11A and 11B are flowcharts showing detailed operations of the control unit 7 in the measurement mode 4b. FIG. 12 shows an example of a calibration result display screen.

As shown in FIG. 6, when the operator turns on the power switch or the calibration instruction button of the operation unit 40 and the calibration start instruction signal S61 is input, the control unit 4 performs the calibration mode in the memory. The calibration mode 4a is started by reading and executing the program (see steps S601 and S602 in FIG. 7). Alternatively, a configuration may be adopted in which a display that prompts the operator to start calibration is displayed on the display unit 10 every time a predetermined time elapses, and an instruction to start calibration is received from the operator.

It should be noted that at the time when step S602 is started, such as when the power switch is turned on or when the calibration instruction button is turned on, the space 30 inside the transducer array 2 is a substance having a known sound velocity, For example, it is filled with water. For example, when the power switch is turned off by the operator on the previous day, a display that prompts the operator to fill the space 30 with, for example, water can be displayed on the display unit 10. According to this, the operator operates to fill the space with water. The calibration instruction button of the operation unit 40 is a two-step switch, and the control unit 4 displays a display prompting the operator to fill the space 30 with, for example, water when the first step is operated. It is also possible to configure so that the second-stage switch cannot be operated unless the operator inputs to the operation unit 40 that the water has been filled. In addition, a device that fills the space 30 with water (not shown), for example, is used in combination with the ultrasonic transmission / reception device 5, or a device (not shown) that fills the space 30 with water, for example, is provided in the ultrasonic transmission / reception device 5. It is also possible to fill the space 30 with water at the start of S602.

The calibration mode 4a will be specifically described with reference to the sequence diagram of FIG. In the calibration mode 4a, the control unit 4 accesses the parameter storage unit 19 of the storage unit 9 and reads various parameter values for calibration (see step S101 in FIG. 8). This parameter value is a value set as a default value or a value stored by the previous calibration. For example, the parameters are the position coordinates of each transducer 1 in the transducer array 2, the signal response times R1t and R2t in the transmission operation and reception operation of each transmission / reception unit 3, and the signal conversion gain in the transmission operation and reception operation of each transmission / reception unit 3. R1A, R2A, transmission signal waveform, reception filter constant, and the like are included.

Next, as shown in FIG. 6, the control unit 4 transmits a transmission / reception operation instruction signal S63 to each transmission / reception unit 3, causes a predetermined transmission / reception unit 3a to perform a transmission operation, and causes the other transmission / reception units 3b and 3c to perform transmission operations. By performing the receiving operation, the ultrasonic signal S21 is propagated to the space 30 (step S102).

As shown in FIG. 8B, the specific ultrasonic wave propagation operation in step S102 is performed by the control unit 4 while changing the transducer 1 to be transmitted. First, the control unit 4 selects the N = 1st transmission / reception unit 3 as a transmission / reception unit that performs a transmission operation and selects the remaining transmission / reception unit 3 as a reception unit that performs a reception operation according to the transmission / reception operation instruction signal S63 (step S106). S107). Next, the control unit 4 outputs the electrical signal S1 of the transmission signal waveform read out as the parameter value from the parameter storage unit 19 to the transmission unit 6 of the transmission / reception unit 3 selected as the transmission unit, and generates the transmission signal S11. Then, a reception filter constant or the like is set as a parameter value to the transmission / reception unit 3 selected as the reception unit, and a reception operation is instructed. Thereby, the ultrasonic signal S21 is transmitted from the transducer 1 connected to the transmission / reception unit 3 selected as the transmission unit, and is received by the transducer 1 connected to the reception unit 7 of the transmission / reception unit 3 selected as the reception unit. (Step S108). The reception signal S31 is filtered and amplified by the reception unit 7 to generate an amplified reception signal S41 and is output to the control unit 4.

The control unit 4 calculates a signal delay time PRt that is a difference between the timing T4 at which the amplified reception signal S41 is output from the reception unit 7 and the timing T1 at which the electrical signal S1 is output to the transmission unit 6, and serves as the transmission unit. Calculation is made for each combination of the selected transmission / reception unit 3 and the transmission / reception unit 3 selected as the reception unit, and is written in the storage unit 9 (step S109). The information written in the storage unit 9 may include signal waveform data of the amplified received signal S41 in addition to the signal delay time PRt.

The control unit 4 repeats the operations in steps S107 to S109 until the transmission operation is performed with all the N transmitting / receiving units 3 as transmission units (steps S110 and S111). Thus, step S102 for propagating the ultrasonic signal S21 to the space 30 is completed. Note that step S109 for calculating and writing the signal delay time PRt to the storage unit 9 may be performed collectively after step S110 in which it is determined that all of the N transmission / reception units 3 are to be transmitted.

In addition, in step S107, the transmission / reception part 3 which the control part 4 selects as a transmission part is not restricted to one, Plural may be sufficient. A plurality of transmission / reception units 3 may be simultaneously operated to transmit a composite wave of ultrasonic signals. Further, the transmission / reception unit 3 selected by the control unit 4 as the reception unit may not be all except the transmission / reception unit 3 selected as the transmission unit. The positional relationship with the transmission / reception unit 3 that performs the transmission operation and the shape of the transducer array 2 The transmission / reception unit 3 selected according to the environment inside the transducer array 2 may be used. For example, it is possible to perform a reception operation only on the transmission / reception unit 3 connected to the transducer 1 that is a predetermined distance or more away from the transducer 1 connected to the transmission / reception unit 3 to be transmitted. Further, the transmission / reception unit 3 that has performed the transmission operation may be instructed to perform the reception operation and receive the reflected wave of the transmitted ultrasonic signal S21.

Next, the control unit 4 proceeds to step S103 in FIG. 8A, and reads out information on the signal delay time PRt for all the transmission / reception units 3 stored in step S109 from the storage unit 9. Then, a new parameter value is calculated based on all the signal delay times PRt (step S104). Specifically, the position coordinates of all the transducers 1 in the transducer array 2, the signal response time R1t in the transmission operation of all the transmission / reception units 3, and the signal response time R2t in the reception operation are obtained as new parameter values. The detailed operation of step 104 will be described later in detail.

Next, the control unit 4 writes the new parameter values (position coordinates and signal response times R1t, R2t) obtained in step S104 into the parameter storage unit 19 of the storage unit 9 as calibrated parameter values and displays them. The information is displayed on the unit 10 (step S105).

Then, the control unit 4 displays on the display unit 10 a display for confirming to the operator whether or not the measurement mode may be performed based on the calibration result (new parameter value) (step S603 in FIG. 7). If the operator agrees, the control unit 4 proceeds to the measurement mode (step S604). On the other hand, if the operator determines that it is not appropriate to perform the measurement mode with the parameter values after calibration, maintenance (step S607) or the like can be instructed. Note that it is also possible to write the calibrated parameter value in the parameter storage unit 19 after the operator agrees in step S603. Further, it may be simplified such that confirmation of the calibration result to the operator (step S603) is omitted, and only that the calibration is completed is notified. Or you may substitute by changing to other states, such as a state which can receive the measurement start instruction demonstrated below and an ultrasonic transmission / reception apparatus.

According to the above steps 602 and 603, the position coordinates of the transducer 1 in the transducer array 2 and the signal response time of the transmission / reception unit 3 can be calibrated.

Here, the operation in which the control unit 4 obtains a new parameter value in step 104 will be described in detail with reference to the flowchart of FIG. First, the control unit 4 is based on the parameter values (vibrator position coordinates, signal response times R1t, R2t) read from the parameter storage unit 19 in step S101 and the sound speed of the substance filled in the space 30. The signal delay time PRt is calculated (step S164). Specifically, the control unit 4 calculates the distance between the transducers 1 that have transmitted and received from the position coordinates of the transducers read from the parameter storage unit 19, and divides this by the sound speed, The ultrasonic propagation time P1t of the parameter value (default) is calculated. Further, the control unit 4 calculates the default signal delay time PRt by adding the calculated ultrasonic propagation time P1t and the signal response times R1t and R2t of the transmission / reception unit 3 connected to these transducers. .

Next, the control unit 4 calculates the difference between the signal delay time PRt read in step S103 and the default signal delay time PRt calculated in step S164 (step S165). Thereby, since the signal delay time PRt read out in step S103 is the signal delay time actually measured by transmitting and receiving ultrasonic waves in step S102, the difference from the default signal delay time PRt is not more than a predetermined value (for example, If the sum of squares of the signal delay time difference is within a predetermined value), the position coordinates of the parameter values and the signal response times R1t and R2t read from the parameter storage unit 19 in step S101 are the current position coordinates of the transducer 1 and the transmission / reception unit. The signal response times R1t and R2t are within a predetermined value. Therefore, when the difference between the two is within the predetermined value, the control unit 4 does not calculate the new position coordinates and the signal response times R1t and R2t, and proceeds to step S105 as it is (step S166). On the other hand, if the difference is larger than the predetermined value in step S166, the process proceeds to step S167 to calculate the current position coordinates of the transducer 1 and the signal response times R1t and R2t of the transmission / reception unit.

In steps S167 to S173, new position coordinates and signal response times R1t and R2t are set, the signal delay time PRt calculated from the new position coordinates and signal response times R1t and R2t, and the signal delay time PRt measured in step S102. The new position coordinates and signal response times R1t and R2t are calculated by the least square method so that the sum of squares of the difference between the two is minimized.

First, the X coordinate of the N = 1st vibrator is changed within a predetermined range with a predetermined step size, and other position coordinates and signal response times R1t and R2t are obtained using values read from the parameter storage unit 19. The signal delay time PRt is calculated. As a result, the position coordinate X that minimizes the sum of squares of the difference between the signal delay time PRt calculated from the new position coordinates X and Y and the signal response times R1t and R2t and the signal delay time PRt measured in step S102 is calculated. (Step S168). Next, the Y coordinate of the N = 1st vibrator is changed within a predetermined range with a predetermined step size, the X coordinate is the coordinate calculated in step S168, and the signal response times R1t and R2t are parameter storage units. The signal delay time PRt is calculated using the value read from 19. Thereby, the position coordinate Y that minimizes the sum of squares of the difference between the signal delay time PRt calculated from the new position coordinates X and Y and the signal response times R1t and R2t and the signal delay time PRt measured in step S102 is calculated. (Step S169).

Next, the signal response time R1t of the transmission unit 6 of the transmission / reception unit 3 to which the N = 1st transducer is connected is changed within a predetermined range with a predetermined step size, and the position coordinates of the transducer are stepped. Using the coordinates calculated in S168 and 169, the signal response time R2t is calculated using the value read from the parameter storage unit 19, and the signal delay time PRt is calculated. Accordingly, the signal response time R1t that minimizes the sum of squares of the difference between the signal delay time PRt calculated from the new position coordinates X and Y and the signal response times R1t and R2t and the signal delay time PRt measured in step S102 is obtained. Calculate (step S170). Similarly, the signal response time R2t of the reception unit 7 of the transmission / reception unit 3 to which the N = 1st transducer is connected is changed within a predetermined range with a predetermined step size, and the position coordinates of the transducer are set in steps. The signal delay time PRt is calculated using the coordinates calculated in S168 and 169 and the signal response time R1t using the value calculated in step S170. Thereby, the signal response time R2t that minimizes the sum of squares of the difference between the signal delay time PRt calculated from the new position coordinates X and Y and the signal response times R1t and R2t and the signal delay time PRt measured in step S102 is obtained. Calculate (step S171).

The above steps S168 to 171 are repeated for all (N) vibrators 1 (steps S172 and 173). As a result, new position coordinates and signal response times R1t and R2t with a minimum error from the signal delay time PRt measured in step S102 can be calculated as new parameter values, and step S104 is completed.

In the above steps 168 to 171, when calculating the value that minimizes the sum of squares of the difference, if the sum of squares of the difference is less than or equal to a predetermined value, or the amount of decrease in the difference is less than or equal to the predetermined value. When the number of calculations reaches a predetermined number, it may be determined that the sum of squares of the difference is minimized.

In steps S168 to S171, when the sum of squares of the signal delay time difference between the transmission / reception units 3 is obtained, the signal delay time PRt between the transmission / reception units 3 (between the transducers 1) may be weighted. For example, as shown in FIGS. 3D and 3E, when the transducer array 2 is configured by a combination of the transducer subarrays 11, an error between the position coordinates of the transducer 1 and the signal response time for each transducer subarray 11. Is considered to have a tendency, so that each transducer subarray 11 is weighted. Alternatively, since there is a structural difference between the vibrator 1 located at the end of the vibrator sub-array 11 and the vibrator 1 located outside the vibrator sub-array 11, it is possible to perform weighting in consideration of this.

In addition, the vibrator 1 has directivity for transmitting and receiving ultrasonic signals due to the element shape, the matching layer, the acoustic lens, and the like. For this reason, in steps 168 to 171, the signal response times R 1 t and R 2 t may be added with directivity typical to the vibrator 1 having the structure. In addition, in some cases, typical directivity characteristics may be greatly different between the vibrator 1 located at the end of the vibrator sub-array 11 and the vibrator 1 located at other positions. Depending on the position in the sub-array 11, typical directivity suitable for each of the signal response times R1t and R2t may be added.

In step S104 in which the position coordinates and the signal response times R1t and R2t are calculated in steps S164 to S173, the number of parameters of the pair of transducers 1 and the transmission / reception unit 3 is the distance between the transducers 1 and the transmission / reception unit. The signal response time R1t in the transmission operation 3 and the signal response time R2t in the reception operation of the transmission / reception unit 3 are three. Therefore, when there are N sets of transducers 1 and transmission / reception units 3, the number of parameters is 3N. On the other hand, the signal delay time PRt to be measured is N × (N−1) because it is a combination of the transducer 1 and the transceiver 3. That is, 3N parameters are obtained by N × (N−1) simultaneous equations. If N is 4 or more, 3N parameters can be uniquely obtained except for other error factors. Therefore, a restriction may be provided such that only the transducer 1 and the transmission / reception unit 3 that are separated by a predetermined distance or more perform a reception operation on the transducer 1 and the transmission / reception unit 3 that perform a transmission operation. In this case, even if the number of the transducers 1 and the transmission / reception units 3 that perform the reception operation is reduced to half, if N is 7 or more, 3N parameters can be uniquely obtained. If the distance between the transducers 1 is known, the position coordinates that are the relative positional relationship of the transducers 1 can be obtained by the principle of triangulation, and the reception operation is performed using this. The number of vibrators 1 may be reduced.

When the position coordinates and signal response time values obtained in step S104 described above differ from the values before calibration (default) by a predetermined value or more, other parameters (transmission signal waveform, signal conversion in transmission operation) The gain R1A, the signal conversion gain R2A in the reception operation, and the parameters such as the reception filter constant may be corrected in the same manner. These corrected parameter values are also written in the parameter storage unit 19 as calibrated parameter values.

Next, the measurement mode (step S604) in FIG. 7 will be described in detail with reference to FIGS.

When the operator agrees in step S603 described above, or when the operator instructs measurement via the operation unit 40, the control unit 4 executes the measurement mode (step 604). Before starting the measurement mode, the operator places a measurement target in the space 30 inside the transducer array 2. Note that the control unit 4 may automatically start the measurement mode by an automatic control program or the like, triggered by the fact that the measurement target is installed in the space 30 inside the transducer array 2.

First, as shown in FIGS. 10 and 11A, the control unit 4 reads the values of various parameters from the parameter storage unit 19 of the storage unit 9 (step S112). This parameter includes the position coordinates of each transducer 1 and the signal response times R1t and R2t of each transceiver 3. In addition, a transmission signal waveform, transmission signal strength, signal conversion gains R1A and R2A of the transmission / reception unit 3, reception filter constants, and the like may be included. The position coordinates of the transducer and the signal response times R1t and R2t are values calibrated in the calibration mode 602.

Next, the control unit 4 transmits a transmission / reception operation instruction signal 63 to each transmission / reception unit 3, causes the predetermined transmission / reception unit 3 a to perform transmission operation, and causes the other transmission / reception units 3 b and 3 c to perform reception operation. The sound wave signal S21 is propagated to the space 30 (step S113).

Specific ultrasonic wave propagation operation in step S113 is performed by the control unit 4 while changing the vibrator 1 to be transmitted as shown in FIG. 11B. First, the N = 1 first transmission / reception unit 3 is selected as a transmission / reception unit that performs a transmission operation, and the remaining transmission / reception units 3 are selected as reception units that perform a reception operation (steps S117 and S118). Next, the control unit 4 outputs the electrical signal S1 of the transmission signal waveform read out as the parameter value from the parameter storage unit 19 to the transmission unit 6 of each transmission / reception unit 3 selected as the transmission unit, and generates the transmission signal S11. At the same time, a reception filter constant or the like is set as a parameter value to the transmission / reception unit 3 selected as the reception unit and a reception operation is instructed (step S119). Thereby, the ultrasonic signal S21 is transmitted from the transducer 1 connected to the Nth transceiver unit 3 selected as the transmission unit (step S119).

Subsequently, the Nth transmitting / receiving unit 3 selected as the transmitting unit is selected as a receiving unit, a receiving filter constant or the like is set as a parameter value, and a receiving operation is instructed (step S120). As a result, the ultrasonic signal S21 transmitted from the Nth transmitter / receiver 3 passes through the measurement target A arranged in the space 30 as shown in FIG. 5B, and a part thereof depends on the measurement target. Reflected and transmitted waves and reflected waves are received by the vibrator 1 connected to the Nth transmitter / receiver 3, and the reflected wave from the measurement target is connected to the Nth transmitter / receiver 3 that has transmitted the ultrasonic signal S 21. The received transducer 1 also receives the signal (step S121). The reception signal S31 of each transducer 1 is filtered and amplified by the reception unit 7 of the connected transmission / reception unit 3 to generate an amplified reception signal S41 and is output to the control unit 4.

The control unit 4 calculates a signal delay time PRt that is a difference between the timing T4 at which the amplified reception signal S41 is output from the reception unit 7 and the timing T1 at which the electrical signal S1 is output to the transmission unit 6. Further, the signal strength of the amplified received signal S41 may be calculated. The calculated signal delay time PRt and the like are written in the storage unit 9 for each combination of the transmission / reception unit 3 selected as the transmission unit and the transmission / reception unit 3 selected as the reception unit (step S122). The information to be written in the storage unit 9 may include signal waveform data of the received signal S41 after amplification in addition to the signal delay time PRt and the intensity information.

The operations in steps S118 to S122 are repeated until all the N transmission / reception units 3 perform transmission operations (steps S123 and S124). Note that step S122 for calculating and storing the signal delay time PRt may be performed after the repetition determination S123.

In addition, in step S118, the transmission / reception part 3 which the control part 4 selects as a transmission part is not restricted to one, Plural may be sufficient. A plurality of transmission / reception units 3 may be simultaneously operated to transmit a composite wave of ultrasonic signals. The transmission / reception unit 3 selected as the reception unit by the control unit 4 is a part selected according to the positional relationship with the transmission / reception unit 3 that performs the transmission operation, the shape of the transducer array 2, and the environment inside the transducer array 2. The transmission / reception unit 3 may be used.

Next, the control unit 4 proceeds to step S114 in FIG. 11A, and reads out the signal delay times PRt for all the transmission / reception units 3 stored in step S113 from the storage unit 9. When the signal strength of the received signal S41 after amplification is written in the storage unit 9, this is also read. The calculation unit 20 of the control unit 4 uses the parameters such as the read signal delay time PRt, the signal intensity, and the position coordinates of the transducer after calibration read in step S112, the shape of the measurement target, the sound speed, A physical property value distribution (map) such as an attenuation amount is calculated, and the calculated shape and physical property value distribution (map) are stored (stored) in the storage unit 9 (step S115). Specifically, the shape image of the measurement target is a plurality of receptions set in the space 30 by receiving signals from the transducer that has received the ultrasonic signal reflected by the measurement target, as in a general ultrasonic imaging apparatus. It can be generated by performing phasing addition (reception beam forming) for the time focus and converting the signal intensity after phasing addition into luminance. It is also possible to generate a shape image by detecting the boundary of the sound velocity or attenuation distribution in the sound velocity distribution or attenuation distribution that describes the generation method. The sound speed distribution image can be generated as follows. The calculation unit 20 subtracts the signal response times R1t and R2t of each transmission / reception unit 3 that are the parameters after calibration read in step S112 from the read signal delay time PRt, thereby transmitting and receiving the ultrasonic wave. The ultrasonic wave propagation time P1t of the ultrasonic signal S21 between 1 is obtained. Further, the distance between the transducers 1 that have transmitted and received the ultrasonic signal S21 is calculated from the position coordinates of the transducers 1 that are the parameters after calibration read in step S112. The average sound speed of the ultrasonic signal S21 is obtained by dividing the obtained distance between the transducers by the ultrasonic wave propagation time P1t. By calculating this for all combinations of the transmission / reception units 3 (vibrators 1) that transmit and receive the ultrasonic signal S21, the average sound velocity at each angle when the ultrasonic signal S21 is transmitted from various angles to the measurement target. Can be requested. Since the average sound speed is an average of the sound speed distribution of the path through which the ultrasonic wave has passed (propagated), a known tomography method such as matrix calculation is used so as not to contradict the average sound speed in various paths. Thus, the sound speed distribution (sound speed map) to be measured can be calculated. Thereby, it is possible to generate a sound velocity distribution image of the measurement target on the plane where the transducer array 2 is arranged. When the signal intensity of the amplified received signal S41 is read from the storage unit 9, an attenuation distribution image can be generated as follows. The arithmetic unit 20 calculates the signal strength of the amplified received signal S41, the signal strength of the electrical signal S1 output from the control unit 4 to the transmission unit 6, and the signal conversion gains R1A and R2A of the transmission / reception unit 3 read in step S112. It is possible to calculate the average attenuation amount between the transducers 1 that have transmitted and received the ultrasonic signal S21. The average attenuation is an average of the attenuation distribution of the path through which the ultrasonic signal S21 passes (propagated). Therefore, the attenuation distribution (attenuation map) of the measurement target is obtained by using the calculation processing of a known tomography method such as matrix calculation using the average attenuation when the ultrasonic signal S21 is transmitted from various angles. Can be calculated. Thereby, it is possible to generate an attenuation distribution image of the measurement target on the plane on which the transducer array 2 is arranged.

The operation in the measurement mode may be performed with a plurality of signal strengths, signal frequencies, signal waveforms, and the like.

The calculated shape of the measurement target and the distribution (map) of physical property values such as sound speed and attenuation are displayed on the display unit 10 together with information such as the shape and physical property value (step S116). Note that these measurement results may be displayed together with various parameter values after calibration read from the storage unit 9 in step S112. By displaying various parameter values, the measurement result and the characteristics of the ultrasonic transmission / reception apparatus 5 can be managed in association with each other.

When step S116 is completed, the control unit 4 causes the display unit 10 to display a display asking the operator whether to turn off the power and end the measurement or to continue the measurement (step in FIG. 6). S605). If the operator selects not to turn off the power (No) via the operation unit 40, the control unit 4 returns to step S604 and repeats the measurement mode. On the other hand, when the operator selects to turn off the power (Yes), the control unit 4 displays a display that prompts the interior space 30 of the transducer array 2 to fill a predetermined liquid (for example, water). 10 is displayed. When the operator who sees this fills the space 30 with a predetermined liquid and notifies (confirms) this to the control unit 4 via the operation unit 40, the control unit 4 turns off the power. Accordingly, since the space 30 is filled with a predetermined liquid from the next time the power is turned on (step S601), the calibration mode is executed without bothering the operator. (Step S602).

It should be noted that after the measurement result is displayed (step S116), the measurement result confirmation signal can be received from the operator via the operation unit 40. Alternatively, the ultrasonic transmission / reception apparatus can be configured to transition to another state such as a pause state or a state where a measurement start instruction can be accepted.

As described above, according to the present embodiment, the position coordinates of the calibrated transducer 1, the signal response times R1t and R2t of the transmission / reception unit 3, the measured signal delay time, and the ultrasonic reception signal intensity By using this, it is possible to measure the shape of the measurement object and the physical property values such as the sound speed and the attenuation amount with high accuracy.

Here, a mode in which the calibration result is displayed on the display unit 10 in step S105 will be described with reference to FIG. The display unit 10 can display the position coordinates after calibration and the values of the signal response times R1t and R2t as they are. Further, for example, an ultrasonic signal is transmitted / received to / from an object having a known shape and a physical property value such as sound velocity and attenuation amount in the same manner as in the measurement mode of FIGS. And signal response times R1t and R2t can be used to perform matrix calculation (ultrasonic tomography method) and display the calculated shape of the same object and an image of physical property values such as sound speed and attenuation. FIG. 12 is a screen example of the display unit 10 that displays the calibration result, and has display areas 81 to 84 that display values of position coordinates and signal response times R1t and R2t, and a known shape, sound speed, and attenuation. An ultrasonic signal is transmitted to and received from an object (standard phantom), and the shape image, sound velocity image, and attenuation amount of the standard phantom calculated by the ultrasonic tomography method using the calibrated position coordinates and signal response times R1t and R2t. Display areas 85 to 87 for displaying images. In the

display areas

81 and 82, the differences (errors) between the values of the X and Y coordinates after calibration of each transducer 1 and the initial values (values before calibration) are displayed as graphs. In the

display areas

83 and 84, the differences (errors) between the signal response times R1t and R2t after calibration of the transducers 1 and the initial values (values before calibration) are displayed as graphs. In the display screen of FIG. 12, a calibration result approval switch (object that accepts an operation for approving the calibration result in step S603 of FIG. 7 from the user who has seen the calibration results shown in the display areas 81 to 87. ) 89 can also be displayed. In addition, a calibration re-execution switch (object) 88 that accepts an instruction to re-execute the calibration mode 4a from the user can also be displayed on the display screen. By displaying the display screen as shown in FIG. 12 in step S105, the user can easily grasp the value of the calibration result and the image when the object (standard phantom) is measured using the calibration result. Can do. Therefore, it is possible to support the user's judgment on whether to approve the calibration result or to re-execute it on the display screen.

Furthermore, the calibration result may be finely adjusted based on the known shape of the same object (standard phantom) and physical property values such as sound speed and attenuation. For example, in the calibration mode 4a, when the temperature of the water filling the space 30 is different from the assumption, and the sound speed of the water filling the space 30 used in step S104 is 1% faster, the image of the shape of the object is 1% It is displayed small. In this case, the calibrated parameter value related to the distance (positional coordinate) between the transducers 1 is also shortened by 1%. Therefore, fine adjustment is performed so that the distance between the vibrators 1 is increased by 1%. In this way, it is possible to increase the certainty of the calibrated parameter value.

The calibration mode 4a of the control unit 4 described above is configured to calculate a new parameter value so that the difference between the measured signal delay time and the signal delay time obtained from the parameter value is minimized. However, the method of calculating the parameter value in the calibration mode is not limited to this method, and other methods can be used. Hereinafter, as a modification, a calibration mode 4a using another calculation method will be described.

<Modification 1-1>
In the modified example 1-1, the sound velocity of the substance filling the space 30 inside the transducer array 2 is changed to form a plurality of sound velocity states, and the signal delay time is measured each time. An example of calibrating the signal response times R1t and R2t will be described.

FIG. 13 is a flowchart for explaining the operation of the calibration mode 4a (step S602 in FIG. 6) of the modified example 1-1. In FIG. 13, steps that perform the same operation as the step of FIG.

First, the control unit 4 reads parameters such as the position coordinates of the transducer 1 and the signal response time of the transmission / reception unit 3 from the parameter storage unit 19 (step S101). Next, the control unit 4 arranges a first sonic material (for example, water adjusted to a predetermined first temperature) (step S132). Specifically, the control unit 4 prompts the operator to fill the space 30 with the first sonic substance (step S132). For example, the control unit 4 displays a predetermined display on the display unit 10. If the control unit 4 confirms that the operator has filled the space 30 with the first sonic substance through the operation of the operation unit 40, an ultrasonic signal transmission / reception operation is performed (step S102-1). The operation in step S102-1 is the same as the operation in FIG. 8B (steps S106 to S111). The ultrasonic signal S21 is transmitted to the space 30, the signal delay time PRt is measured, and stored in the storage unit 9. To do. However, the predetermined value for setting the number of repetitions in step S110 can be reduced as compared to the case of executing steps S106 to S111 in FIG. 8B in step S102 of FIG.

Next, the control unit 4 arranges a second sonic material (for example, water adjusted to a predetermined second temperature) (step S134). Specifically, the operator is prompted to fill the space 30 with the second sonic material (step S134). For example, the control unit 4 displays a predetermined display on the display unit 10. If the control unit 4 confirms that the operator has filled the space 30 with the second sonic substance through the operation of the operation unit 40, an ultrasonic signal transmission / reception operation is performed (step S102-2). The operation in step S102-2 is the same as the operation in FIG. 8B (steps S106 to S111). The ultrasonic signal S21 is transmitted to the space 30, the signal delay time PRt is measured, and stored in the storage unit 9. To do. However, the predetermined value for setting the number of repetitions in step S110 can be reduced as compared to the case of executing steps S106 to S111 in FIG. 8B in step S102 of FIG. The first sonic substance and the second sonic substance may be realized by changing the temperature of the same substance, or may be realized by changing the concentration of the solution, or by changing the type of substance. It may be realized.

In the above steps S132 and S134, the operation in which the control unit 4 arranges the space 30 with the first and second sound velocity substances does not prompt the operator, but the ultrasonic transmission / reception device 5 automatically creates the space 30. It is also possible to configure so as to be filled with the first sonic material and the second sonic material. For example, the ultrasonic transmitting / receiving apparatus 5 includes a device that selectively supplies the first sonic substance and the second sonic substance to the space 30 and fills the space 30 with the supplied sonic substance.

Next, the control unit 4 reads the signal delay time PRt measured by filling the space 30 with the first and second sound velocity substances in the above-described steps S102-1, 102-2 from the storage unit 9 (step S102-1). S103), a difference between the signal delay time PRt1 measured by arranging the first sonic substance and the signal delay time PRt2 measured by arranging the second sonic substance is calculated (step S137). Since the signal response times R1t and R2t of the transmission / reception unit 3 included in the signal delay time PRt1 and the signal delay time PRt2 are equal, the difference (PRt1−PRt2) is an ultrasonic propagation time P1t in which the ultrasonic signal S21 has propagated through the space 30. Is the difference. At this time, since the position coordinates of the transducer 1 are constant regardless of the sound velocity substance, the distance between the transducers 1 can be calculated from the difference in signal propagation time (PRt1−PRt2) and the difference in sound velocity. The control unit 4 obtains the position coordinates of each transducer 1 from the calculated distance between the transducers 1 by the least square method and stores it in the parameter storage unit 19 (step S138). Thereafter, using the obtained position coordinates of the transducer 1 and the measured signal delay times PRt1 and PRt2, the signal response times R1t and R2t of the transmission / reception unit 3 are obtained by the least square method and stored in the parameter storage unit 19 (step S139). The operations in steps S138 and S139 are performed in the same manner as the operations in steps S164 to S173 in FIG. Finally, the calibration results of the position coordinates of the transducer 1 and the signal response times R1t and R2t are displayed on the display unit 10 (step S105).

By using the above calibration mode operation, the position coordinates of the transducer 1 in the transducer array 2 and the signal response time of the transmission / reception unit 3 can be calibrated with higher accuracy.

<Modification 1-2>
In Modification 1-2, the transducer array 2 includes a drive unit that adjusts the position of the transducer 1, and the transmission / reception unit 3 has a function of adjusting the signal response time. The operation of the calibration mode 4a suitable for such a configuration will be described.

FIG. 14 is a flowchart for explaining the operation of the calibration mode 4a (step S602 in FIG. 6) of the modified example 1-2. In FIG. 14, steps that perform the same operations as those in FIG. 8A are denoted by the same reference numerals.

The control unit 4 reads the position coordinates of the transducer 1 and the signal response times R1t and R2t of the transmission / reception unit 3 from the parameter storage unit 19 (step S101). The control unit 4 controls the driving unit of the transducer 1 and the adjustment function of the transmission / reception unit 3, and the position coordinates of each transducer 1 and the signal response time of the transmission / reception unit 3 are read in step S <b> 101 and the signal response. Adjustments are made to the values of time R1t and R2t (step S141). Then, an ultrasonic signal transmission / reception operation is performed (step S102). The operation in step S102 is the same as the operation in FIG. 8B. The ultrasonic signal S21 is transmitted, the signal delay time PRt is measured, and stored in the storage unit 9.

Next, the signal delay time PRt measured in step 102 is read from the storage unit 9 (step S103). Using the read signal delay time PRt, the position coordinates adjusted in step S142, and the signal response times R1t and R2t, the position coordinates are obtained by the operations in steps S164 to S173 in FIG. 9 in the same manner as in step S104 in FIG. And signal response times R1t and R2t are calculated and stored in the parameter storage unit 19 (step S104-1). The specific operation in step 104 is the same as the operation in steps S164 to S173 in FIG.

Next, the control unit 4 calculates the sum of squares of errors between the signal delay time PRt calculated in step S104-1, and the signal delay time PRt ′ in the preferable position coordinates and signal response time determined in advance. It is determined whether the error sum of squares has converged (step S142). For example, when the error sum of squares is less than a predetermined value, or when the amount of decrease from the previous error sum of squares is less than a predetermined value, the above steps S141, S102 to S103 and S104-1 are performed. If it has been carried out a predetermined number of times, it is determined that it has converged. The preferred position coordinates and signal response time use values obtained from the ideal position and signal response time of the transducer 1 obtained from the shape of the transducer array 2, for example.

If the error sum of squares does not converge in step S142, it means that the position coordinates and signal response time of the vibrator 1 adjusted in step S141 are not appropriate. Therefore, the position coordinates and the signal response time calculated in step S104-1 and stored in the parameter storage unit 19 are adopted (updated) as values to be adjusted (step S143), the process returns to step S141, and each transducer 1 Are adjusted to the values adopted (updated) in step S143. Thereafter, steps S102, S103, S104-1, and S142 are repeated.

On the other hand, if the error sum of squares has converged in step S142, the position coordinates calculated in step S104-1 and stored in the parameter storage unit 19 and the signal response times R1t and R2t are displayed as calibration results. (Step S105-1).

According to the operation of the calibration mode of the modification 1-2, it is possible to compensate for errors included in the function of adjusting the signal response time of the driving unit that adjusts the position of the transducer 1 and the transmission / reception unit 3. Therefore, the position coordinates of the transducer 1 and the signal response times R1t and R2t of the transmission / reception unit 3 can be calibrated with higher accuracy. In addition, measurement can be performed at the originally preferred position coordinates of the vibrator 1 and the signal response times R1t and R2t of the transmission / reception unit 3.

<Modification 1-3>
In the calibration mode of the modified example 1-3, past information on the calibrated position coordinates of the transducer 1 and the signal response time of the transmission / reception unit 3 is stored. Specifically, the control unit 4 stores in the storage unit 9 the signal response characteristics and the position information of the vibrator obtained by calibration performed in the past. Thereby, it is possible to detect deterioration or failure of the ultrasonic transmission / reception apparatus 5 by displaying the past calibration result.

FIG. 15 is a flowchart of the control unit 4 for explaining an operation example in the calibration mode of the ultrasonic transmission / reception device 5 according to Modification 1-3. In FIG. 15, steps that perform the same operations as those in FIG. 14 are denoted by the same reference numerals.

In FIG. 15, steps S101 to S104-1 are the same as steps S101, S102, S103, and S104-1 in FIG. Next, the control unit 4 reads the past calibration result (for example, the position coordinates and signal response time calculated in the previous calibration) from the parameter storage unit 19 (step S144), and the position calculated in the current calibration. The coordinates and the signal response time are displayed (step S145). Next, the control unit 4 calculates the sum of squares of the difference (error) between the current and past calibrated position coordinates and the signal response time, and determines whether it is larger than a predetermined value (step S146). Note that the determination method in step S146 is not limited to the sum of squares of errors, and whether one of the calibrated position coordinates of each transducer 1 or the signal response time of each transmission / reception unit 3 is greater than a predetermined value. Whether the change in the sum of squares in the past calibration and the current calibration is a time-series graph as shown in FIG. 15B, and whether the change amount of the sum of squares is larger than a predetermined value. You may judge by.

If it is determined in step S146 that the error is larger than the predetermined value, an alert is displayed (step S147) because it is considered that there is a failure or deterioration of the ultrasonic transmission / reception device 5.

If the flow of operation as described above is used as the calibration mode, deterioration or failure of the ultrasonic transmission / reception device 5 can be monitored, and appropriate maintenance can be performed. Moreover, an appropriate measurement result can be acquired by grasping the degree of deterioration or failure.

<Modification 1-4>
In the calibration mode of Modification 1-4, calibration is performed by removing position coordinates and signal response times with large errors.

FIG. 16A is a flowchart showing the operation in the calibration mode of the control unit 4 of the ultrasonic transmission / reception apparatus 5 according to Modification 1-4, and FIG. 16B is a flowchart showing the operation in the measurement mode. It is.

Steps S101 to S103 and S104-1 in FIG. 16A in the calibration mode are the same as steps S101, 102, 103, and 104-1 in FIG. 14, and the control unit 4 determines the position coordinates in step S104-1. The signal response time is calculated and stored in the storage unit 9. The position coordinates and signal response time calculated in step S104-1 are referred to as parameter set A.

Next, the control unit 4 obtains an error between the position coordinates and signal response time (parameter set A) calculated in step S104-1, and the position coordinates and signal response time read from the parameter storage unit 19 in step S101. Then, it is determined whether there is a larger value than the predetermined value (step S148). For example, if there is no error larger than a predetermined value, the calibration result (parameter set A) is displayed in step S151, and the calibration operation is terminated.

On the other hand, when there is a position coordinate or a signal response time having an error larger than a predetermined value in step S148, the control unit 4 removes (erases) the signal delay time PRt related to them (step S149) and remains. Using the signal delay time PRt, the position coordinates of the parameter storage unit 19 and the signal response time, the position coordinates and the signal response time are calculated again in the same manner as in step S104-1, and stored in the storage unit 9 (step S104). -2). The position coordinates and signal response time calculated in step S104-2 are referred to as parameter set B. Then, the control unit 4 displays the position coordinates and signal response time (parameter set B) calculated in step 104-2, and the position coordinates and signal response time (parameter set A) calculated in step S104-1. And one of the parameter sets A and B is selected by the operator via the operation unit 40 (step S151).

By doing this, it is possible to prevent the signal delay time related to the vibrator 1 and the transmission / reception unit 3 suspected of being broken or deteriorated from affecting the calibration results of the other transducers 1 and the transmission / reception unit 3. However, since it can be considered that the transducer 1 and the transmission / reception unit 3 suspected of being broken or deteriorated can be calibrated, the calibration result (parameter set A) obtained in step S104-1 and the step S104 Both the calibration results (parameter set B) obtained in -2 are displayed in step S151. In step S151, instead of allowing the operator to select one, for example, the control unit 4 may automatically select and display a calibration result with a small error sum of squares. In addition, when selecting the operator, an object having a known shape and a physical property value such as sound speed and attenuation is arranged in the space 30 and the same operation as in the measurement mode is performed, so that the object in both the parameter sets A and B can be selected. The measurement result (shape, distribution of physical property values, etc.) may be displayed. By doing so, the operator can easily recognize the difference between the images of the parameter sets A and B, and as a result, can be easily selected.

It should be noted that the determination condition in step 148 described above can be variously considered in addition to the above-described conditions. For example, the determination may be made based on whether the sum of squares of the difference between the calculated position coordinates or signal response time and the position coordinates or signal response time stored in the parameter storage unit 19 is greater than a predetermined value. Alternatively, the determination step S148 may be omitted, and the calibration results of both parameter sets A and B may always be calculated. Further, the maximum value of the error between the calculated position coordinate or signal response time and the position coordinate or signal response time stored in the parameter storage unit 19 is minimized, or each transducer 1 and each transmission / reception unit 3 is weighted. In addition, the sum of squared errors may be minimized. For example, when the transducer array 2 is configured by a combination of the transducer subarrays 11, the transducer subarray 11 is considered to have an error in the position coordinates of the transducer 1 and the signal response time for each transducer subarray 11. Each can be weighted. Alternatively, since there is a structural difference between the vibrator 1 located at the end of the vibrator sub-array 11 and the vibrator 1 located outside the vibrator sub-array 11, it is possible to perform weighting in consideration of this.

On the other hand, in the measurement mode, as shown in FIG. 16B, the measurement is performed in the same manner as steps S112 to S114 in FIG. However, when reading the parameters after calibration in step S112 in FIG. 16B, the control unit 4 displays in step S151 if the error is less than or equal to a predetermined value in step S148 in the calibration mode. If the error is greater than the predetermined value in step S148, the parameter set B selected in step S151 is read. And the control part 4 performs transmission / reception of an ultrasonic signal by performing step S113, S114, and reads the signal strength of the measured signal delay time PRt and the amplified received signal S41. Next, the control unit 4 determines whether or not the error is larger than the predetermined value in the above-described step S148, and the parameter set B is selected in step S151 (step S152), and when the parameter set B is selected. Removes (erase) data of the set of the transducer 1 and the transmission / reception unit 3 from which the signal delay time has been removed in step S149 described above from the data of the signal delay time and signal intensity read in step S114 (step S153). . Similar to step S115 in FIG. 11A, the remaining signal delay time and signal intensity are used to calculate the shape of the measurement target and the distribution of physical property values (sound speed and attenuation) (step S115), and the calculation result (measurement) (Result) is displayed on the display unit 10 (step S116).

On the other hand, when the parameter set A is selected in step S151 and when the parameter set A is displayed as the calibration result in step S151 because the error is equal to or smaller than the predetermined value in step S148 (step S152). The control unit 4 uses the signal delay time and the signal intensity read in step S114 as they are to calculate the shape of the measurement target and the distribution of physical property values (sound speed and attenuation) (step S115), and the calculation result (measurement result). ) Is displayed on the display unit 10 (step S116).

It should be noted that both parameter sets A and B are selected in step S151 in the calibration mode, and the shape and physical property values (sound speed and attenuation amount) of the measurement target are used by using each parameter set A and B when operating in the measurement mode. ) Distribution and a plurality of calculation results (measurement results) may be displayed. In that case, an operator or a user of measurement results may select the most suitable one (desired result) from a plurality of measurement results.

Here, a mode in which the calibration result is displayed on the display unit 10 in step S151 will be described with reference to FIG. The display screen of FIG. 17 includes display areas 181 to 184 for displaying the position coordinates after calibration and the values of the signal response times R1t and R2t, as in FIG. Further, for example, a shape image and physical properties of the same object calculated by transmitting and receiving an ultrasonic signal to a standard phantom having a known shape and physical property values such as sound velocity and attenuation amount, for example, in the measurement mode of FIG. It further includes display areas 85-1, 85-2, 85-3 for displaying value images and the like. In the display areas 181 to 184, the difference (error) between the X coordinate, Y coordinate, signal response time R1t, R2t after calibration of each transducer 1 and the initial value (value before calibration) is Each of the parameter sets A, B, and C is displayed as an appearance frequency graph. In the display areas 85-1, 85-2, and 85-3, in the example of FIG. 17, standard phantom shape images calculated using the parameter sets A, B, and C are displayed, respectively. The parameter sets A and B are respectively obtained in steps S104-1 and 104-2 in the calibration mode in FIG. The parameter set C is a parameter set calculated in step S104-1 or S104-2 with the determination conditions in step 148 described above being different from those in the case of parameter sets A and B. As described above, for example, a determination condition that minimizes the sum of squares of errors after weighting each transducer 1 and each transmission / reception unit 3 can be used as the different determination conditions. By displaying the display screen as shown in FIG. 17 in step S151, the user can easily compare the values of the plurality of parameter sets A, B, and C and the results of measuring the object (standard phantom) using them. Can be grasped. Therefore, it is possible to support the user's judgment as to whether to approve the selection of the parameter sets A and B and the calibration result by using the display screen.

As described above, when the configuration of the ultrasonic transmission / reception apparatus according to the second embodiment is applied, the shape of the measurement target, the sound speed, and the attenuation amount are obtained by calibrating the position coordinates of the transducer 1 and the signal response time of the transmission / reception unit 3. It is possible to measure physical property values such as with high accuracy.

Further, the position of the vibrator 1 and the setting of the signal response time are corrected during the calibration operation, and the calibration operation is repeated again in the corrected state, thereby obtaining the position coordinates of the vibrator 1 and the signal response time of the transmission / reception unit 3. Each can be calibrated with high accuracy.

<< Third embodiment >>
An ultrasonic transmission / reception apparatus according to the third embodiment will be described.

The ultrasonic transmission / reception apparatus of the third embodiment is the same as that of the second embodiment, but the second embodiment calculates the signal response times R1t and R2t as the signal response characteristics R1 and R2, but the third embodiment Then, the signal conversion gains R1A and R2A are calculated and the calibration is performed.

The configuration of the ultrasonic transmission / reception apparatus according to the third embodiment is the same as the configuration of FIG.

As shown in FIG. 1B, the intensity of the electrical signal S1 received by the transmitter 6 from the controller 4 is A1, the intensity of the ultrasonic signal S21 transmitted by the transducer 1a is A2, and the other transducer 1d is transmitted. The intensity of the reached ultrasonic signal S21 is A3, and the intensity of the amplified received signal S41 output from the receiving unit 7 is A4. The signal conversion gain R1A at the time of transmission is represented by A2 / A1, and the signal conversion gain R2A at the time of reception is represented by A4 / A3. The signal strength ratio (signal gain) PRA of the electric signal S1 and the amplified received signal S41 is represented by A4 / A1.

The parameter storage unit 19 of the storage unit 9 stores previously obtained values such as the signal conversion gains R1A and R2A of each transmission / reception unit 3 and the position coordinates of each transducer 1 in the transducer array 2.

FIG. 18A shows an example of the arrangement of the transducers 1 in the transducer array 2. FIGS. 18B to 18G are tables showing examples of information stored in the parameter storage unit 19 of the storage unit 9. The parameter storage unit 19 stores the position coordinates of the

transducers

1a, 1b, and 1c as shown in the table of FIG. Further, the signal conversion gain R1A between the

transducers

1a, 1b, 1c and the transmission unit 6 of the transmission / reception units 3a, 3b, 3c, and the reception unit 7 of the

transducers

1a, 1b, 1c and the transmission / reception units 3a, 3b, 3c. The signal conversion gain R2A between and is stored in the parameter storage unit 19 as shown in the table of FIG. For example, the signal conversion gain R1A in the transmission operation of the transmission / reception unit 3a is 1 kPa / V, and the signal conversion gain R2A in the reception operation is 1 mV / Pa.

Further, in the parameter storage unit 19, the signal intensity ratio (PRA) A4 / A1 of the transmission signal and the reception signal between the transmission / reception units 3 when the space 30 is filled with a predetermined substance is also shown in FIG. It is stored like the table shown. In FIG. 18D, the space 30 surrounded by the transducer array 2 is filled with a substance whose attenuation can be regarded as 0 dB, and when the energy of the ultrasonic signal S21 is attenuated in proportion to the distance, the transmission signal The signal intensity ratio (PRA = A4 / A1) of the received signal is −28.45 dB. This is because the ultrasonic wave propagation gain P1A proportional to the distance between the transducers obtained from the position coordinates of the

transducers

1a and 1b, the signal conversion gain R1A in the transmission operation of the transmission unit 6a of the transmission / reception unit 3a, and the transmission / reception unit 3b This is the sum of the signal conversion gain R2A in the receiving operation of the receiving unit 7b.

FIG. 18E shows a table of position coordinates stored in the parameter storage unit 19 when the position coordinates of the vibrator 1b are shifted by 0.2 mm toward the vibrator 1a along the x axis. Such positional coordinate deviation (error) is caused by manufacturing variations of the transducer 1b, assembly errors of the transducer array 2, and the like. FIG. 18 (f) is an example of a table showing signal conversion gains R1A and R2A when the signal conversion gain in the transmission operation of the transmission / reception unit 3c is 0.1 kPa / V lower than the table of FIG. 18 (c). is there. Such an error in the signal conversion gain R1A is due to deterioration with time of each component or change in use environment, manufacturing variation of the transducer 1c, manufacturing variation of the transmission unit 6c, and manufacturing of a cable connecting the transducer 1c and the transmission unit 6c. This may be caused by variations, an intensity error of the electric signal S1 input from the control unit 4 to the transmission unit 6c, and the like. In the case of the position coordinates and the signal conversion gains R1A and R2A shown in FIGS. 18E and 18F, the signal intensity ratio PRA is as shown in the table shown in FIG. The difference between the tables in FIGS. 18D and 18G is due to the error of the position coordinate of the transducer 1b and the error of the signal conversion gain in the transmission operation of the transmission / reception unit 3c.

The operation of the control unit 4 will be specifically described. The overall operation flow of the control unit 4 is the same as in FIG. 7 of the second embodiment.

In the calibration mode 4a of step S601 in FIG. 7, the control unit 4 performs calibration as shown in the flow of FIGS. 19 (a) and 19 (b). In the flow of FIGS. 19A and 19B, the same steps as those in the flow of FIGS. 8A and 8B of the second embodiment are denoted by the same reference numerals, and description thereof is omitted.

The control unit 4 reads various parameter values from the parameter storage unit 19 of the storage unit 9 (step S201 in FIG. 19A). The parameters include position coordinates of each transducer 1 in the transducer array 2, signal conversion gains R1A and R2A, transmission signal waveforms, reception filter constants, and the like in the transmission and reception operations of each transmission / reception unit 3. Next, the control unit 4 causes the predetermined transmission / reception unit 3a to perform transmission operation, and causes the other transmission / reception units 3b and 3c to perform reception operation to propagate the ultrasonic signal S21 to the space 30 (step S202). Specifically, as shown in FIG. 19 (b), as in steps S106 to S108 in FIG. 8 of the second embodiment, the transmission / reception unit 3 that performs transmission operation and the reception unit that performs reception operation are selected, and the transmission unit 6 outputs the electrical signal S1, causes the transducer 1 to transmit the ultrasonic signal S21, and causes the reception unit 7 of the selected transmission / reception unit 3 to receive the signal, thereby obtaining an amplified reception signal S41.

The control unit 4 calculates and stores a signal intensity ratio PRA that is a ratio of the intensity A1 of the electric signal S1 and the intensity A4 of the amplified received signal S41 (step S209). This is repeated while changing the vibrator 1 (steps S110 and S111).

Next, the control unit 4 proceeds to step S203 in FIG. 17A, and reads out the signal intensity ratio PRA for all the transmission / reception units 3 stored in step S209 from the storage unit 9. Based on all signal strength ratios PRA, the signal conversion gain R1A in the transmission operation and the signal conversion gain R2A in the reception operation of all the transmission / reception units 3 are calculated (calculated) by the least square method (step S204). Since the method of calculating the signal conversion gains R1A and R2A by the least square method can be the same as the method described with reference to FIG. 9 in the second embodiment, detailed description thereof is omitted here.

Next, the control unit 4 writes the position coordinates and signal conversion gains R1A and R2A obtained in step S204 as calibrated parameter values in the parameter storage unit 19 of the storage unit 9 and displays them on the display unit 10 ( Step S205).

Next, the measurement mode (step S604 in FIG. 6) of the control unit 4 will be described. The measurement mode of the third embodiment is the same as the measurement mode of FIGS. 11A and 11B of the second embodiment. Only the difference between the measurement mode of the third embodiment and the measurement mode of the second embodiment will be described below. Unlike the second embodiment, the parameters read in step S112 always include the signal conversion gains R1A and R2A of the transmission / reception unit 3, and the signal conversion gains R1A and R2A are values calibrated in the calibration mode 602. It is. In step S122 of FIG. 11B, unlike the second embodiment, in addition to the signal propagation time PRt, the signal strength ratio PRA between the electric signal S1 and the amplified received signal S41 is always calculated, and the storage unit 9 (Step S122). Further, in step S114 of FIG. 11A, the signal propagation time PRt and the signal strength ratio PRA are read from the storage unit 9. In step S115, using the parameters such as the read signal propagation time PRt, the signal intensity ratio PRA, and the position coordinates of the transducer read in step S112, the shape of the measurement target and the distribution of physical property values such as attenuation ( Map). A specific method for calculating the attenuation map is the same as the method described in the second embodiment. Briefly, the calculation unit 20 calculates the signal intensity ratio PRA and the signal of the transmission / reception unit 3 read in step S112. From the conversion gains R1A and R2A, an average attenuation amount between the transducers 1 that have transmitted and received the ultrasonic signal S21 is calculated, and a known tomo is used using the average attenuation amount when the ultrasonic signal S21 is transmitted from various angles. The attenuation distribution (attenuation map) of the measurement target is calculated by the graphic method. As in the second embodiment, it is also possible to calculate the sound speed distribution (sound speed map) to be measured based on the signal propagation time PRt.

Here, the manner in which the calibration result is displayed on the display unit 10 in step S205 will be described with reference to the display screen example of FIG. The display screen of FIG. 20 can display the position coordinates (X, Y coordinates) after calibration and the values of the signal conversion gains R1A and R2A in the areas 81 to 84, as in FIG. A shape image calculated by transmitting and receiving ultrasonic waves using the position coordinates after calibration and signal response times R1t and R2t with respect to the phantom, a physical property value image such as a sound velocity distribution and an attenuation distribution, and display areas 85 to 87 It is also possible to display them respectively. In addition, on the display screen of FIG. 20, a calibration result approval switch 89 and a calibration re-execution switch 88 can be displayed together as in FIG. By displaying the display screen as shown in FIG. 20 in step S205, the user can easily grasp the value of the calibration result and the image when the standard phantom is measured using the calibration result. Therefore, it is possible to support the user's judgment on whether to approve the calibration result or to re-execute it on the display screen.

As described above, according to the present embodiment, using the calibrated signal conversion gains R1A and R2A and the measured signal intensity ratio PRA or the like, the distribution of physical property values such as the attenuation amount and sound speed of the measurement target Can be measured with high accuracy.

Hereinafter, as a modification, the calibration mode 4a using another calculation method will be described.

<Modification 2-1>
In the modified example 2-1, by changing the attenuation rate of the substance filling the space 30 inside the transducer array 2 to form a plurality of attenuation rate states, and measuring the signal intensity ratio PRA each time, the transducer 1 An example of calibrating the position coordinates and the signal conversion gains R1A and R2A will be described.

FIG. 21 is a flowchart for explaining the operation of the calibration mode 4a of the modified example 2-1. Steps that perform the same operations as those in FIG. 13 are denoted by the same reference numerals.

First, the control unit 4 reads parameters such as the position coordinates of the transducer 1 and the signal conversion gain of the transmission / reception unit 3 from the parameter storage unit 19 (step S201), and a first attenuation factor substance (for example, a predetermined first The operator is prompted to fill the space 30 with water added with a mixture at a concentration of (step S232). If the operator fills the space 30 with the first attenuation factor substance, the control unit 4 performs an ultrasonic signal transmission / reception operation (step S202-1). The operation in step S202-1 is the same as the operation in FIG. 19B, and the intensity ratio (signal intensity ratio PRA) between the received signal and the transmitted signal is measured and stored.

Next, the operator is prompted to fill the space 30 with a second attenuation material (for example, water added with a mixture at the second concentration) (step S234), and an ultrasonic signal transmission / reception operation is performed (step S202-). 2). The operation in step S202-2 is the same as the operation in FIG. 19B, and the signal intensity ratio PRA is measured and stored. The signal intensity ratio PRA measured in the space 30 with a plurality of attenuation factor substances is read (step S236), and the signal intensity ratio PRA1 measured by arranging the first attenuation substance and the second attenuation factor substance are arranged and measured. The difference in the signal intensity ratio PRA2 is calculated (step S237). Since the signal conversion gains R1A and R2A of the transmission / reception unit 3 included in the signal intensity ratio PRA1 and the signal intensity ratio PRA2 are equal, the difference (PRA1−PRA2) is an ultrasonic propagation when the ultrasonic signal S21 propagates through the space 30. This is the difference in gain P1A. At this time, since the position coordinates of the vibrator 1 are constant regardless of the attenuation factor substance, the distance between the vibrators 1 can be calculated from the difference in signal propagation gain (PRA1−PRA2) and the difference in attenuation factor. The control unit 4 obtains the position coordinates of each transducer 1 from the calculated distance between the transducers 1 by the least square method in the same manner as step S138 in FIG. 13, and stores it in the parameter storage unit 19 (step S238). Thereafter, using the obtained position coordinates of the transducer 1 and the measured signal intensity ratios PRA1 and PRt2, the signal conversion gains R1A and R2A of the transmission / reception unit 3 are obtained by the least square method and stored in the parameter storage unit 19 (step) S239). Finally, the position coordinates of the transducer 1 and the calibration results of the signal conversion gains R1A and R2A are displayed on the display unit 10 (step S205).

In steps S232 and S234, instead of prompting the operator, the ultrasonic transceiver 5 may automatically fill the space 30 with the first attenuation material and the second attenuation material, A device that fills the space 30 with the first attenuation material and the second attenuation material and the ultrasonic transmission / reception device 5 may be used in combination.

By using the above calibration mode operation, the position coordinates of the transducer 1 in the transducer array 2 and the signal conversion gain of the transmission / reception unit 3 can be calibrated with higher accuracy.

<Modification 2-2>
As a modified example 2-2, FIG. 22 shows a flowchart of an operation example in the calibration mode. In this example, the signal intensity ratio (A4 / A1) is measured for the signal intensity A1 of the plurality of electric signals S1, and the position coordinates and the signal conversion gain for each signal intensity are calibrated.

The control unit 4 reads the position coordinates of the default transducer 1 and the signal conversion gain of the transmission / reception unit 3 from the parameter storage unit 19 (step S201), and sets the first transmission electric signal intensity as the intensity A1 of the electric signal S1. Setting is made (step S241-1). For example, an intermediate value (typical value) of the intensity of the electric signal S1 that can be set in the transmission / reception unit 3 is set. Then, similarly to steps S202 and S203 in FIG. 19A, an ultrasonic signal is transmitted / received (step S202-1), the measured signal intensity ratio PRA is read (step S203-1), and similarly to step S204. After calculating the position coordinates and the signal conversion gain, they are stored in the storage unit 9 (step S204-1).

Next, the second transmission electric signal intensity is set as the intensity A1 of the electric signal S1 (step S241-2). For example, it is the maximum value of the intensity of the electric signal S1 that can be set in the transmission / reception unit 3. Then, as in the above steps S202-1 to 204-1, the ultrasonic signal is transmitted and received (step S202-2), the measured signal intensity ratio PRA is read (step S203-2), and the position coordinates and the signal conversion gain are calculated. Calculation is performed (step S204-2).

Finally, the position coordinates and signal conversion gain at each transmission electric signal intensity A1 calculated in steps S204-1 and S204-2 are displayed (step S205).

Further, as shown in FIG. 22 (b), the calibration results for a plurality of types of transmission electric signal strengths A1 are shown in the relationship between the transmission electric signal strength A1 and the signal conversion gain in the transmission operation of the transmission / reception unit 3, or in step S202-1. , S202-2, the relationship between the received electrical signal strength A4 and the signal conversion gain in the reception operation of the transceiver 3 can be displayed as a graph or the like. In an electronic circuit such as an amplifier constituting the transmission / reception unit 3, the amplification factor gradually decreases as the voltage of the input / output signal increases, and it becomes impossible to output a voltage having a certain amplitude or more limited by the power supply voltage. Therefore, in the operation in the measurement mode, it is preferable to compensate the signal conversion gain suitable for each of the obtained transmission electric signal strength A1 and reception electric signal strength A4. The transmission ultrasonic signal intensity A2 may be used instead of the transmission electric signal intensity A1, or the reception ultrasonic signal intensity A3 may be used instead of the reception electric signal intensity A4.

In addition to the intensity of the electric signal S1, calibration may be performed by switching the amplifier gain, the filter constant, and the like of the receiving unit 7. Thereby, since the signal conversion gain at the time of various settings of the receiving unit 7 is known, more accurate calibration can be performed. Similarly, calibration may be performed by changing the signal frequency or signal waveform.

If the above operation flow is applied, the position coordinates of the transducer 1 in the transducer array 2 and the signal conversion gain of the transmission / reception unit 3 are calibrated in consideration of nonlinearity with respect to the signal intensity of the transducer 1 and the transmission / reception unit 3. be able to.

<Modification 2-3>
In Modification 2-3, the transducer array 2 includes a drive unit that adjusts the position of the transducer 1, and the transmission / reception unit 3 has a function of adjusting the signal conversion gain. The operation of the calibration mode 4a suitable for such a configuration will be described.

FIG. 23 is a flowchart for explaining the operation of the calibration mode 4a of the modified example 2-3, and calibration is performed by the same processing as the flowchart of FIG. In FIG. 23, steps that perform the same operations as those in FIG. 19A are denoted by the same reference numerals.

The control unit 4 reads the position coordinates of the transducer 1 and the signal conversion gains R1A and R2A of the transmission / reception unit 3 from the parameter storage unit 19 (step S201). The control unit 4 controls the drive unit of the transducer array 2 and the adjustment function of the transmission / reception unit 3, and the position coordinates and signals of the transducers 1 and the signal conversion gain of the transmission / reception unit 3 read out in step S <b> 201. Adjustment (compensation) is performed to the values of the conversion gains R1A and R2A (step S251). Then, an ultrasonic signal transmission / reception operation is performed (step S202). The operation in step S202 is the same as the operation in FIG. 19B, and the signal intensity ratio PRA is measured and stored.

Thereafter, as in steps 203 and 204 of FIG. 19A, the signal strength ratio PRA is read (step S203), and the measured signal strength ratio PRA, the position coordinates adjusted in S241, and the signal conversion gains R1A and R2A are used. The position coordinates and the signal conversion gains R1A and R2A are calculated and stored in the parameter storage unit 19 (step S204-3).

Next, the control unit 4 calculates the sum of squares of errors between the signal intensity ratio PRA newly calculated in step S204-3, the predetermined preferred position coordinates and the signal conversion gain PRA ′, and the sum of squares of errors. It is determined whether or not has converged (step S252). If it is determined in step S252 that the error sum of squares has not converged, the position coordinates and signal conversion gain calculated in step S204 are adopted (updated) as values to be adjusted (step S253), and step S251. Returning to the step, the position of each transducer 1 and the signal conversion gain of the transmission / reception unit 3 are adjusted to the values adopted in step S253. Steps S202 to S204-3 and S252 are repeated. The preferred position coordinates and signal conversion gain use values obtained from the ideal position and signal conversion gain of the transducer 1 obtained from the shape of the transducer array 2, for example.

On the other hand, if it is determined in step S252 that the sum of squared errors has converged, the position coordinates and signal conversion gains R1A and R2A stored in the parameter storage unit 19 are displayed as calibration results (step S105).

According to the operation of the modification 2-3 in the calibration mode, it is possible to compensate for errors included in the function of adjusting the signal conversion gain of the driving unit that adjusts the position of the transducer 1 and the transmission / reception unit 3. Therefore, the position coordinates of the transducer 1 and the signal conversion gains R1A and R2A of the transmission / reception unit 3 can be calibrated with higher accuracy. In addition, measurement is possible using the originally preferred position coordinates of the vibrator 1 and the signal conversion gains R1A and R2A of the transmission / reception unit 3.

<Modification 2-4>
In the calibration mode of the modified example 2-4, past information on the calibrated position coordinates of the transducer 1 and the signal conversion gain of the transmission / reception unit 3 is stored and displayed. Detect failure.

FIG. 24 is a flowchart of the control unit 4 for explaining an example of the operation in the calibration mode of the ultrasonic transmission / reception apparatus 5 according to the modification 2-4. Calibration is performed by the same processing as the flowchart of FIG. Note that, in FIG. 24, steps that perform the same operations as those in FIG.

In FIG. 24, steps S201 to S204-1 are the same as steps S201 to S204 of FIG. 19A, and the control unit 4 converts the position coordinates of the transducer 1 and the signal conversion of the transmission / reception unit 3 from the parameter storage unit 19. The readout of the gain and the transmission / reception operation of the ultrasonic signal are performed, the position coordinate and the signal conversion gain are calculated using the measured signal intensity ratio and the position coordinate and the signal conversion gain stored in the parameter storage unit 19, and then the parameters are calculated. Store in the storage unit 19. Next, the control unit 4 reads out past calibration results (for example, the position coordinates and signal conversion gain calculated in the previous calibration) from the parameter storage unit 19 (step S254), and the position calculated in the current calibration. The coordinates and the signal conversion gain are displayed together (step S255). Next, the control unit 4 determines whether or not the sum of squares of errors between the current and past calibrated position coordinates and the signal conversion gain is larger than a predetermined value (step S256). When it is determined in step S256 that the error is larger than the predetermined value, the control unit 4 displays an alert because it is considered that there is a failure or deterioration of the ultrasonic transmission / reception device 5 (step S257). . Note that the determination method in step S256 is not limited to the sum of squares of errors, and whether or not one of the calibrated position coordinates of each transducer 1 or the signal response time of each transmission / reception unit 3 is greater than a predetermined value. Alternatively, the determination may be made by using a time-series graph as shown in FIG. 24B, and the determination may be made based on whether the amount of change in the sum of squares is larger than a predetermined value.

<Modification 2-5>
In the calibration mode of Modified Example 2-5, calibration is performed by removing position coordinates and signal conversion gains with large errors.

FIG. 25 is a flowchart showing the operation in the calibration mode of the ultrasonic transmitting / receiving apparatus 5 according to the modification 2-5. Calibration is performed by the same processing as in the flowchart of FIG.

Steps S201 to S204-1 in FIG. 25 are the same as steps S201 to S204 in FIG. 19A, and the control unit 4 transmits the position coordinates of the transducer 1 and the signal conversion gain of the transmission / reception unit 3 from the parameter storage unit 19. Is read out, the transmission / reception operation of the ultrasonic signal is performed, and the position coordinates and the signal conversion gain (parameter set A) are calculated using the measured signal intensity ratio and the position coordinates and the signal conversion gain stored in the parameter storage unit 19. Then, it is stored in the storage unit 9. Next, the control unit 4 obtains an error between the position coordinates calculated in step S204 and the signal conversion gain (parameter set A) and the position coordinates read from the parameter storage unit 19 in step S201 and the signal conversion gain. It is determined whether or not there is a value larger than the value of (step S248). For example, if there is no error larger than a predetermined value, the control unit 4 displays the calibration result (parameter set A) in step S251 and ends the calibration operation.

On the other hand, if there is a position coordinate or a signal conversion gain having a larger error than the predetermined value in step S248, the control unit 4 removes the signal strength ratio PRA related to them (step S249), and the remaining signal strength. Using the ratio PRA, the position coordinates and the signal conversion gain of the parameter storage unit 19, the position coordinates and the signal conversion gain (parameter set B) are calculated again in the same manner as in step S204, and then stored in the storage unit 9 (step S204-2). Then, the control unit 4 displays the position coordinates and signal conversion gain (parameter set B) calculated at step 204-2 and (parameter set A) calculated at step S204-1 on the display unit 10, and the operator To select one of the parameter sets A and B via the operation unit 40 (step S251). In addition, when selecting the operator, an object having a known shape and a physical property value such as sound speed and attenuation is arranged in the space 30 and the same operation as in the measurement mode is performed, so that the object in both the parameter sets A and B can be selected. It is also possible to display measurement results (shape, distribution of physical property values, etc.). As a result, the operator can easily recognize the difference between the images of the parameter sets A and B, and as a result, can be easily selected.

25, it is possible to prevent the signal delay time related to the transducer 1 and the transmission / reception unit 3 suspected of being broken or deteriorated from affecting the calibration results of the other transducers 1 or the transmission / reception unit 3. In addition, since it is fully considered that the transducer 1 and the transmission / reception unit 3 suspected of being broken or deteriorated can be calibrated, the calibration results (parameter set A) obtained in step S204-1 and step 204-2. And B) are both displayed.

Here, a mode in which the calibration result is displayed on the display unit 10 in step S251 will be described with reference to FIG. The display screen of FIG. 26 is the same as the display screen of FIG. 17, and display areas 181 to 184 for displaying the position coordinates after calibration and the values of the signal conversion gains R1A and R2A for each of the parameter sets A, B, and C FIG. 17 shows display images 85-4, 85-5, and 85-6 of the shape images of the standard phantom calculated by transmitting and receiving ultrasonic signals to and from the standard phantom using the parameter sets A, B, and C, respectively. Including as well. The parameter sets A, B, and C are the same as those described using FIG. 17 of Modification 1-4 of the second embodiment. By displaying the display screen as shown in FIG. 26 in step S251, the user can easily compare and grasp the values of the plurality of parameter sets A, B, and C and the results of measuring the standard phantom using them. be able to. Therefore, the user's judgment as to whether or not to approve the selection of the parameter sets A and B and the calibration result can be supported by the display screen of FIG.

As described above, when the configuration of the ultrasonic transmission / reception apparatus according to the third embodiment is applied, the position coordinates of the transducer 1 and the signal conversion gain of the transmission / reception unit 3 are respectively calibrated, so that the shape of the measurement target, the attenuation amount, etc. Physical property values can be measured with high accuracy.

Further, in the second embodiment, the signal response times R1t and R2t are calibrated, and in the third embodiment, the signal conversion gains R1A and R2A are calibrated. It is also possible to calibrate the position coordinates of 1, the signal response time of the transmission / reception unit 3, and the signal conversion gain of the transmission / reception unit 3. This makes it possible to measure the shape of the measurement target and the physical property values such as the sound speed and the attenuation amount with higher accuracy.

In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit such as an FPGA. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

3 and FIG. 18, the various information is described using the expression “aaa table”, but the various information may be expressed using a data structure other than the table. In order to show that it does not depend on the data structure, the “aaa table” can be called “aaa information”. In addition, it has been described that each information is recorded in the storage unit 9 and the parameter storage unit 19 with the expressions “store”, “store”, and “write”. However, it is expressed as “register” or “set”. Also good.

Also, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

The present invention can be applied to an ultrasonic transmission / reception apparatus including a plurality of transducers.

DESCRIPTION OF SYMBOLS 1 Vibrator 2 Vibrator array 3 Transmission / reception part 4 Control part 5 Ultrasonic transmission / reception apparatus 6 Transmission part 7 Reception part 8 Transmission / reception switch 9 Storage part 10 Display part 11 Transducer subarray S1, S2 Transmission / reception part setting signal T1 Input timing of electric signal T2 Ultrasound signal emission timing T3 Ultrasound signal arrival timing T4 Amplified reception signal output timing A1 Transmitted electric signal intensity A2 Transmission ultrasonic signal intensity A3 Reception ultrasonic signal intensity A4 Amplified reception signal Strength

Claims

A transducer array including a plurality of transducers, a transmitter connected to at least one transducer among the plurality of transducers, and a reception connected to at least one other transducer among the plurality of transducers Unit, a calculation unit, and a control unit,
The transmission unit receives an electrical signal from the control unit, amplifies the electrical signal to generate a transmission signal, outputs the transmission signal to the connected transducer, and the transducer that receives the transmission signal The transmission signal is converted into an ultrasonic signal and transmitted toward a predetermined space,
The other transducer that has reached the ultrasonic signal that has propagated through the predetermined space converts the ultrasonic signal into a received signal that is an electrical signal, and the receiving unit amplifies and amplifies the received signal. Output the received signal after
The calculation unit calculates an image of an object arranged in the predetermined space based on the amplified reception signal and one or more of a plurality of parameter values obtained in advance,
The parameter value is a signal response characteristic in at least one of the transmitter and the transducer connected to the transmitter, and the transducer and the receiver connected to the transducer. And position information of the vibrator,
The control unit has a calibration mode for adjusting the parameter value. In the calibration mode, the transmission unit and the reception unit are operated to transmit and receive the ultrasonic signal, the signal response characteristic, and the vibration An ultrasonic transmission / reception apparatus that calculates position information of a child.
2. The ultrasonic transmission / reception apparatus according to claim 1, wherein the signal response characteristic is a period from when the transmission unit receives the electrical signal until the transducer connected to the transmission unit transmits the ultrasonic signal. Signal response characteristics during transmission, and reception from when the ultrasonic signal reaches the other transducer until the reception unit connected to the other transducer outputs the amplified received signal An ultrasonic transmission / reception apparatus characterized by having at least one of time signal response characteristics.
2. The ultrasonic transmission / reception apparatus according to claim 1, wherein, in the calibration mode, the control unit receives the electrical signal from the control unit and then the reception unit outputs the amplified reception signal in the calibration mode. Signal delay time until the transducer transmits an ultrasonic signal after the transmission unit receives the electrical signal from the control unit as the signal response characteristics based on the signal delay time Calculating at least one of a transmission signal response time and a reception signal response time from when the ultrasonic signal reaches the other transducer until the receiving unit outputs the amplified reception signal. A featured ultrasonic transmission / reception apparatus.
2. The ultrasonic transmission / reception apparatus according to claim 1, wherein the control unit obtains an intensity ratio between the electrical signal received by the transmission unit from the control unit and an amplified reception signal output from the reception unit, and the intensity. Based on the ratio, as the signal response characteristics, a signal conversion gain at the time of transmission between the electrical signal and the ultrasonic signal transmitted by the transducer, and the ultrasonic signal reaching the other transducer and An ultrasonic transmission / reception apparatus that calculates at least one of the signal conversion gains during reception between the amplified reception signals.
The ultrasonic transmission / reception apparatus according to claim 1, wherein the control unit adjusts the parameter value used by the calculation unit to calculate the image based on the signal response characteristic and the position information calculated in the calibration mode. An ultrasonic transmission / reception device.
The ultrasonic transmission / reception apparatus according to claim 1, wherein the control unit has a measurement mode in which an ultrasonic signal is transmitted to the object and the calculation unit calculates the image, and the calculation is performed in the calibration mode. And adjusting at least one of a transmission signal transmission condition of the transmission unit and a reception condition of the reception signal of the reception unit in the measurement mode based on the signal response characteristic and the position information. Transmitter / receiver.
The ultrasonic transmission / reception apparatus according to claim 1, further comprising a drive unit that displaces a position coordinate of the transducer.
The ultrasonic transmission / reception apparatus, wherein the control unit operates the drive unit according to the position information calculated in the calibration mode to adjust the position coordinates of the transducer.
2. The ultrasonic transmission / reception apparatus according to claim 1, wherein the calculation unit is configured to determine, based on the reception signal and the parameter value, the other vibration in which the transmission unit and the reception unit are connected to each other. An ultrasonic transmission / reception apparatus characterized in that a propagation characteristic of the ultrasonic signal with a child is obtained, and an image of a physical property value of the object is calculated based on the propagation characteristic of the ultrasonic signal.
The ultrasonic transmission / reception apparatus according to claim 1, wherein the transducer array is disposed so as to surround the predetermined space,
The other transducer to which the receiving unit is connected is disposed at a position where the direct wave of the ultrasonic signal transmitted by the transducer to which the transmitting unit is connected reaches. Transmitter / receiver.
2. The ultrasonic transmission / reception device according to claim 1, wherein the transmission unit and the reception unit are connected to the plurality of transducers, respectively.
2. The ultrasonic transmission / reception apparatus according to claim 1, wherein in the calibration mode, the transmission unit and the reception unit are operated to transmit and receive the ultrasonic signal between a plurality of sets of the transducers, and the transmission unit. Calculating the signal response characteristics and the position information of the transducer by a predetermined calculation method based on the electric signal input to the signal and the amplified received signal output from the receiver. Ultrasonic transmitter / receiver.
2. The ultrasonic transmission / reception apparatus according to claim 1, wherein in the calibration mode, a plurality of substances having different physical property values are sequentially arranged in the predetermined space, and each time the ultrasonic signal is transmitted between the set of transducers. The signal response characteristic and the position information of the transducer are calculated based on the amplified reception signal transmitted and received and the electric signal input to the transmission unit. Sound wave transmitter / receiver.
2. The ultrasonic transmission / reception apparatus according to claim 1, wherein in the calibration mode, intensities of electric signals input to the transmission unit are sequentially set to different types of intensities, and the ultrasonic signals are set for each of the plural types of intensities. The signal response characteristic and the position information of the transducer are calculated based on the amplified reception signal transmitted and received and the electric signal input to the transmission unit. Sound wave transmitter / receiver.
The ultrasonic transmission / reception apparatus according to claim 11, wherein the control unit stores the signal response characteristic obtained by the calibration performed in the past and position information of the transducer in a storage unit. Ultrasonic transmitter / receiver.
An electric signal is input to the transmission unit, the electric signal is amplified by the transmission unit to generate a transmission signal, and the transmission signal is output to the transducer. The transducer that receives the transmission signal transmits the transmission signal to the ultrasonic wave Convert it into a signal and send it to a given space,
The ultrasonic signal propagating in the predetermined space is received by the other transducer, converted into a received signal that is an electrical signal, and the received signal is amplified by a receiving unit and an amplified received signal is output. ,
An ultrasonic transmission / reception method for calculating an image of an object arranged in the predetermined space based on the amplified reception signal and one or more of a plurality of parameter values obtained in advance,
The parameter value is a signal response characteristic in at least one of the transmitter and the transducer connected to the transmitter, and the transducer and the receiver connected to the transducer. And position information of the vibrator,
An ultrasonic transmission / reception method comprising: a calibration mode for transmitting and receiving the ultrasonic signal by the transmission unit and the reception unit and calculating the signal response characteristic and position information of the transducer.