WO2021176630A1 - Ultrasonic measurement device - Google Patents

Ultrasonic measurement device Download PDF

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Publication number
WO2021176630A1
WO2021176630A1 PCT/JP2020/009307 JP2020009307W WO2021176630A1 WO 2021176630 A1 WO2021176630 A1 WO 2021176630A1 JP 2020009307 W JP2020009307 W JP 2020009307W WO 2021176630 A1 WO2021176630 A1 WO 2021176630A1
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WO
WIPO (PCT)
Prior art keywords
time
signal
timing
circuit
ultrasonic
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PCT/JP2020/009307
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French (fr)
Japanese (ja)
Inventor
亨 近藤
公成 田宮
政康 金沢
Original Assignee
オリンパス株式会社
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Application filed by オリンパス株式会社 filed Critical オリンパス株式会社
Priority to PCT/JP2020/009307 priority Critical patent/WO2021176630A1/en
Publication of WO2021176630A1 publication Critical patent/WO2021176630A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B17/00—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
    • G01B17/02—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations for measuring thickness
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/36—Detecting the response signal, e.g. electronic circuits specially adapted therefor

Definitions

  • the present invention relates to an ultrasonic measuring device.
  • FIG. 21 shows the configuration of the conventional ultrasonic measuring device 1001.
  • the ultrasonic measuring device 1001 shown in FIG. 21 includes an ultrasonic vibrator 1010, a drive circuit 1020, a CPU (Central Processing Unit) 1030, a pulse cutoff circuit 1040, a first amplifier 1050, a second amplifier 1060, and an ADC (Analog). -To-Digital Controller) 1070.
  • a CPU Central Processing Unit
  • ADC Analog
  • the CPU 1030 generates a pulse TXpre and outputs the pulse TXpre to the drive circuit 1020.
  • the drive circuit 1020 generates a drive signal TX at the timing of receiving the pulse TXpre, and outputs the drive signal TX to the ultrasonic vibrator 1010.
  • the ultrasonic vibrator 1010 is a piezoelectric element.
  • the ultrasonic vibrator 1010 generates an ultrasonic signal based on the drive signal TX, and irradiates the subject to be measured with the ultrasonic signal.
  • the ultrasonic signal applied to the subject is reflected at the interface of the subject.
  • the ultrasonic signal (reflected signal) reflected at the interface of the subject is incident on the ultrasonic vibrator 1010.
  • the ultrasonic vibrator 1010 receives the reflected signal and generates an echo signal RX based on the reflected signal.
  • the ultrasonic vibrator 1010 outputs the generated echo signal RX to the pulse cutoff circuit 1040.
  • the pulse cutoff circuit 1040 removes the signal component from the echo signal RX by cutting off an unnecessary signal component.
  • the pulse cutoff circuit 1040 outputs the echo signal RXac from which unnecessary signal components have been removed to the first amplifier 1050.
  • the first amplifier 1050 is an LNA (Low Noise Amplifier).
  • the first amplifier 1050 generates the echo signal RXac1 by amplifying the echo signal RXac with a fixed gain.
  • the first amplifier 1050 generates the echo signal RXac1 so as to minimize the noise given to the echo signal RXac.
  • the first amplifier 1050 outputs the generated echo signal RXac1 to the second amplifier 1060.
  • the second amplifier 1060 is a PGA (Programable Gain Amplifier).
  • the second amplifier 1060 generates the echo signal RXac2 by amplifying the echo signal RXac1 with a preset gain.
  • the second amplifier 1060 outputs the generated echo signal RXac2 to the ADC 1070.
  • the ADC 1070 generates a digital echo signal RXd by performing AD conversion on the analog echo signal RXac2.
  • the ADC 1070 outputs the generated echo signal RXd to the CPU 1030.
  • the CPU 1030 uses the timings of the pulse TXpre and the echo signal RXd to determine the timing at which the drive signal TX is output to the ultrasonic vibrator 1010 and the timing at which the echo signal RX is output from the ultrasonic vibrator 1010. Calculate the difference between.
  • the CPU 1030 calculates the thickness of the subject based on the calculated difference.
  • Patent Document 1 discloses an apparatus that directly and easily measures the time based on the echo signal of the ultrasonic signal and calculates the thickness of the subject based on the time.
  • the device uses a comparator and a counter to measure the time it takes for the voltage of the echo signal to exceed a predetermined voltage.
  • the device calculates the thickness of the subject based on the measured time.
  • FIG. 22 shows the time for the ultrasonic signal to propagate.
  • a cross section of the ultrasonic vibrator 1010 and the subject 1200 is shown.
  • the time Ttof from the timing when the drive signal TX is output to the ultrasonic vibrator 1010 to the timing when the echo signal RX is output from the ultrasonic vibrator 1010 is expressed by the following equation (1).
  • Ttof Tm01 + Tm02 + Tm11 + Tm12 (1)
  • the time Ttof includes the time Tm01, the time Tm02, the time Tm11, and the time Tm12 in the formula (1).
  • the time Tm01 indicates the time from the timing when the drive signal TX is output to the ultrasonic vibrator 1010 to the timing when the ultrasonic signal generated by the ultrasonic vibrator 1010 reaches the subject 1200.
  • the time Tm02 indicates the time from the timing when the ultrasonic vibrator 1010 receives the reflected signal to the timing when the echo signal RX is output from the ultrasonic vibrator 1010.
  • the time Tm11 indicates the time from the timing when the ultrasonic signal reaches the front surface (upper surface) of the subject 1200 to the timing when the ultrasonic signal reaches the back surface (lower surface) of the subject 1200.
  • the time Tm12 indicates the time from the timing when the ultrasonic signal is reflected on the back surface of the subject 1200 to the timing when the reflected signal reaches the ultrasonic vibrator 1010.
  • the thickness of steel may be measured with a resolution of 0.01 mm. In that case, a time resolution of about 3.33 ns corresponding to the speed of sound (about 6000 m / s) in steel is required.
  • a system that continuously performs AD conversion such as the ultrasonic measuring device 1001 shown in FIG. 21, it is necessary to always convert an analog signal into a digital signal. Therefore, the sampling frequency is high and the power consumption is high.
  • An object of the present invention is to provide an ultrasonic measuring device capable of performing time measurement using an ultrasonic signal with high accuracy.
  • the ultrasonic measuring device includes an ultrasonic vibrator, a first comparator, a second comparator, a time measuring circuit, and a time calculating circuit.
  • the ultrasonic vibrator transmits an ultrasonic signal to a subject, receives a reflected signal of the ultrasonic signal from the subject, and generates an echo signal based on the reflected signal.
  • the echo signal has an amplitude on the positive side of the reference voltage and an amplitude on the negative side of the reference voltage.
  • the first comparator compares the voltage of the echo signal with the first threshold value on the positive side of the reference voltage, and the first timing at which the voltage of the echo signal matches the first threshold value. Outputs the first signal with.
  • the second comparator compares the voltage of the echo signal with the second threshold value on the negative side of the reference voltage, and the second timing at which the voltage of the echo signal matches the second threshold value. Outputs the second signal.
  • the time measuring circuit measures the first time from the start timing associated with the timing at which the ultrasonic transducer transmits the ultrasonic signal to the first timing.
  • the second time from the start timing to the second timing is measured based on the second signal.
  • the time calculation circuit calculates the zero cross time, which is the time from the start timing to the zero cross point, based on the first time and the second time.
  • the zero cross point indicates a timing at which the voltage of the echo signal coincides with the reference voltage between the first timing and the second timing.
  • the time measuring circuit may measure at least one of the first time and the second time two or more times.
  • the time calculation circuit may generate a first combination and a second combination by associating the first time and the second time with each other.
  • Each of the first combination and the second combination includes the first time and the second time.
  • the first time of the first combination is different from the first time of the second combination, or the second time of the first combination is the second time of the second combination. Different from.
  • the time calculation circuit may calculate the first difference, which is the difference between the first time of the first combination and the second time of the first combination.
  • the time calculation circuit may calculate a second difference, which is the difference between the first time of the second combination and the second time of the second combination.
  • the time calculation circuit may calculate the zero cross time by using the first combination.
  • the time calculation circuit may calculate the zero cross time by using the second combination.
  • the time calculation circuit when the absolute value of the difference between the first time and the second time is within a predetermined value, the time calculation circuit has the zero cross time. May be calculated.
  • the time measuring circuit includes a first digital value indicating the first time and a second digital value indicating the second time. It may be a TDC (Time-To-Digital) circuit that generates.
  • the time calculation circuit may calculate the zero cross time based on the first digital value and the second digital value.
  • the time measuring circuit may measure at least one of the first time and the second time two or more times.
  • the time measurement circuit may generate at least two or more of the first digital value and the second digital value.
  • the time calculation circuit comprises the first digital value and the corresponding combination of the first time and the second time selected from two or more combinations of the first time and the second time.
  • the zero cross time may be calculated by using the second digital value.
  • the ultrasonic measuring device changes the first threshold value based on at least one of a first number and a second number, and said. Further, there may be a change circuit that changes the second threshold value based on at least one of the first number and the second number.
  • the first number indicates the number of times that the time measuring circuit measures the first time.
  • the second number indicates the number of times that the time measuring circuit measures the second time.
  • the ultrasonic measuring device may further include an amplifier that amplifies the echo signal with a predetermined gain.
  • the change circuit may change the gain based on at least one of the first number and the second number.
  • the ultrasonic measuring device further includes a signal generation circuit that generates a third signal having a first edge and a second edge. May be good.
  • the first edge is synchronized with the first timing.
  • the second edge is synchronized with the second timing.
  • One of the first edge and the second edge is a rising edge.
  • the other of the first edge and the second edge is a falling edge.
  • the time measurement circuit generates the first digital value at the timing when the first edge appears in the third signal, and the time measurement circuit generates the first digital value at the timing when the second edge appears in the third signal.
  • a second digital value may be generated.
  • the ultrasonic measuring device estimates the maximum amplitude of the echo signal based on at least one of the first time and the second time. It may further have an amplitude estimation circuit.
  • the amplitude estimation circuit is based on the difference between one of the first time and the second time and the zero cross time, and is super.
  • the maximum amplitude may be estimated based on the resonance frequency of the sound wave transducer.
  • the ultrasonic measuring device inputs the first time, the second time, the first threshold value, and the second threshold value. It may further have a memory for storing a learning model obtained through machine learning which is used as data and obtains the amplitude of the echo signal as correct answer data.
  • the amplitude estimation circuit may estimate the maximum amplitude based on the first time, the second time, the first threshold, and the second threshold by using the learning model. good.
  • the amplitude estimation circuit when the ultrasonic oscillator transmits the ultrasonic signal to the subject at the first timing, the amplitude estimation circuit has the maximum amplitude. A first amplitude may be estimated.
  • the amplitude estimation circuit estimates the second amplitude, which is the maximum amplitude. You may.
  • the ultrasonic measuring device may further include a corrosion estimation circuit that estimates the degree of corrosion of the subject based on the first amplitude and the second amplitude.
  • the amplitude estimation circuit is a curve showing the amplitude of the echo signal by using at least one of the first time and the second time.
  • the slope of is estimated at the zero cross point, and the maximum amplitude may be estimated based on the slope.
  • the ultrasonic measuring device can perform time measurement using an ultrasonic signal with high accuracy.
  • FIG. 1 shows the configuration of the ultrasonic measuring device 1 according to the first embodiment of the present invention.
  • the ultrasonic measuring device 1 shown in FIG. 1 includes an ultrasonic vibrator 10, a drive circuit 20, a CPU 30 (time calculation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a first comparator. It has 70, a second comparator 80, a first time measuring circuit 90, and a second time measuring circuit 100.
  • the ultrasonic vibrator 10 transmits an ultrasonic signal to a subject, receives a reflected signal of the ultrasonic signal from the subject, and generates an echo signal based on the reflected signal.
  • the echo signal has an amplitude on the positive side of the reference voltage and an amplitude on the negative side of the reference voltage.
  • the first comparator 70 compares the voltage of the echo signal with the first threshold value on the positive side of the reference voltage.
  • the first comparator 70 outputs the first signal at the first timing when the voltage of the echo signal matches the first threshold value.
  • the second comparator 80 compares the voltage of the echo signal with the second threshold value on the negative side of the reference voltage.
  • the second comparator 80 outputs the second signal at the second timing when the voltage of the echo signal matches the second threshold value.
  • the first time measuring circuit 90 measures the first time from the start timing associated with the timing at which the ultrasonic vibrator 10 transmits the ultrasonic signal to the first timing based on the first signal.
  • the second time measurement circuit 100 measures the second time from the start timing to the second timing based on the second signal.
  • the CPU 30 calculates the zero cross time, which is the time from the start timing to the zero cross point, based on the first time and the second time. The zero cross point indicates the timing at which the voltage of the echo signal coincides with the reference voltage between the first timing and the second timing.
  • the CPU 30 generates a pulse TXpre and outputs the pulse TXpre to the drive circuit 20.
  • the CPU 30 sets a start pulse START indicating the start timing of each of the first time measured by the first time measuring circuit 90 and the second time measured by the second time measuring circuit 100 to the first time measuring circuit 90 and the first time measuring circuit 90. It is output to the second time measurement circuit 100.
  • the CPU 30 receives the first digital value TDC1 output from the first time measurement circuit 90 and the second digital value TDC2 output from the second time measurement circuit 100.
  • the CPU 30 calculates the zero cross time based on the first digital value TDC1 and the second digital value TDC2. The specific method for calculating the zero cross time will be described later.
  • the CPU 30 calculates the thickness of the subject based on the zero cross time.
  • a processor such as a DSP (Digital Signal Processor) may be used instead of the CPU 30.
  • the CPU 30 may be configured by a circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).
  • the CPU 30 may read the program and execute the read program.
  • the program includes instructions that define the operation of the CPU 30. That is, the function of the CPU 30 may be realized by software.
  • the program may be provided by a "computer-readable recording medium” such as flash memory.
  • the program may be transmitted from the computer holding the program to the ultrasonic measuring device 1 via the transmission medium or by the transmission wave in the transmission medium.
  • a "transmission medium" for transmitting a program is a medium having a function of transmitting information.
  • the medium having a function of transmitting information includes a network (communication network) such as the Internet and a communication line (communication line) such as a telephone line.
  • the above-mentioned program may realize a part of the above-mentioned function.
  • the above-mentioned program may be a difference file (difference program). The combination of the program already recorded in the computer and the difference program may realize the above-mentioned function.
  • the drive circuit 20 generates a drive signal TX at the timing of receiving the pulse TXpre, and outputs the drive signal TX to the ultrasonic vibrator 10.
  • the ultrasonic vibrator 10 is a piezoelectric element.
  • the ultrasonic vibrator 10 generates an ultrasonic signal based on the drive signal TX, and irradiates the subject to be measured with the ultrasonic signal.
  • the ultrasonic signal applied to the subject is reflected at the interface of the subject.
  • the ultrasonic signal (reflected signal) reflected at the interface of the subject is incident on the ultrasonic vibrator 10.
  • the ultrasonic vibrator 10 receives the reflected signal and generates an echo signal RX based on the reflected signal.
  • the ultrasonic vibrator 10 outputs the generated echo signal RX to the pulse cutoff circuit 40.
  • the pulse cutoff circuit 40 includes a switch and a capacitance.
  • the pulse cutoff circuit 40 removes the signal component from the echo signal RX by cutting off an unnecessary signal component.
  • the pulse cutoff circuit 40 outputs the echo signal RXac from which unnecessary signal components have been removed to the first amplifier 50.
  • the first amplifier 50 is an LNA.
  • the first amplifier 50 generates the echo signal RXac1 by amplifying the echo signal RXac with a fixed gain.
  • the first amplifier 50 generates the echo signal RXac1 so as to minimize the noise given to the echo signal RXac.
  • the first amplifier 50 outputs the generated echo signal RXac1 to the second amplifier 60.
  • the second amplifier 60 is a PGA.
  • the second amplifier 60 generates the echo signal RXac2 by amplifying the echo signal RXac1 with a preset gain.
  • the second amplifier 60 outputs the generated echo signal RXac2 to the first comparator 70 and the second comparator 80.
  • the first comparator 70 receives the echo signal RXac2 and compares the voltage of the echo signal RXac2 with the first threshold value THp on the positive side of the reference voltage. When the voltage of the echo signal RXac2 increases and matches the first threshold value THp, the first comparator 70 sets the first measurement control signal STOP1 (first signal) indicating the first timing. Is output to the time measurement circuit 90 of.
  • the second comparator 80 receives the echo signal RXac2 and compares the voltage of the echo signal RXac2 with the second threshold value THn on the negative side of the reference voltage. The second threshold THn is smaller than the first threshold THp. When the voltage of the echo signal RXac2 increases and coincides with the second threshold value THn, the second comparator 80 sets the second measurement control signal STOP2 (second signal) indicating the second timing to the second. Is output to the time measurement circuit 100 of.
  • the first time measurement circuit 90 and the second time measurement circuit 100 are TDC (Time-To-Digital) circuits.
  • the first time measurement circuit 90 measures the first time from the start timing indicated by the start pulse START to the first timing indicated by the first measurement control signal STOP1.
  • the first time measurement circuit 90 generates and holds a first digital value TDC1 indicating a first time.
  • the first time measurement circuit 90 outputs the generated first digital value TDC1 to the CPU 30.
  • FIG. 23 shows an example of the configuration of the TDC circuit included in the first time measurement circuit 90.
  • the TDC circuit shown in FIG. 23 includes a clock counter 300, a phase clock generation unit 310, a phase detection unit 320, and a decoder 330.
  • the clock counter 300 counts the number of clock CLK pulses (clock number) from the start timing indicated by the start pulse START to the timing indicated by the measurement control signal STOP.
  • the phase clock generation unit 310 generates the clock CLK-90, the clock CLK-180, and the clock CLK-270 based on the clock CLK.
  • the clock CLK-90 has a phase 90 degrees behind the phase of the clock CLK.
  • the clock CLK-180 has a phase 180 degrees behind the phase of the clock CLK.
  • the clock CLK-270 has a phase 270 degrees behind the phase of the clock CLK.
  • the phase clock generation unit 310 outputs the clock CLK, the clock CLK-90, the clock CLK-180, and the clock CLK-270 to the phase detection unit 320.
  • the phase detection unit 320 detects the phase states of the four clocks at the timing indicated by the measurement control signal STOP.
  • the decoder 330 outputs a digital value TDC0 indicating the number of clocks and the phase states of the four clocks. With this configuration, the TDC circuit can perform time measurement with high accuracy with low power consumption without increasing the frequency of the clock.
  • the second time measurement circuit 100 measures the second time from the start timing indicated by the start pulse START to the second timing indicated by the second measurement control signal STOP2.
  • the second time measurement circuit 100 generates and holds a second digital value TDC2 indicating a second time.
  • the second time measurement circuit 100 outputs the generated second digital value TDC2 to the CPU 30.
  • the second time measurement circuit 100 is also composed of a TDC circuit like the first time measurement circuit 90.
  • the pulse cutoff circuit 40 is not essential. Therefore, the echo signal RX may be output from the ultrasonic vibrator 10 to the first amplifier 50.
  • the first amplifier 50 and the second amplifier 60 are not essential. Therefore, the echo signal RXac may be output from the pulse cutoff circuit 40 to the first comparator 70 and the second comparator 80. Alternatively, the echo signal RX may be output from the ultrasonic transducer 10 to the first comparator 70 and the second comparator 80.
  • FIG. 2 shows the waveform of each signal in the ultrasonic measuring device 1.
  • the waveforms of the pulse TXpre, the drive signal TX, the start pulse START, the echo signal RX, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG.
  • the horizontal direction in FIG. 2 indicates time, and the vertical direction in FIG. 2 indicates the voltage of each signal.
  • the CPU 30 outputs the pulse TXpre to the drive circuit 20 at the timing tg1.
  • the drive circuit 20 generates a drive signal TX based on the pulse TXpre, and outputs the drive signal TX to the ultrasonic vibrator 10.
  • the ultrasonic vibrator 10 generates an ultrasonic signal based on the drive signal TX and irradiates the subject with the ultrasonic signal. In the example shown in FIG. 2, for the sake of simplicity, the difference between the timing at which the CPU 30 outputs the pulse TXpre to the drive circuit 20 and the timing at which the ultrasonic transducer 10 outputs the ultrasonic signal is ignored.
  • the ultrasonic signal is reflected at the interface of the subject, and the reflected signal is incident on the ultrasonic vibrator 10.
  • the ultrasonic vibrator 10 receives the reflected signal and generates an echo signal RX based on the reflected signal.
  • the echo signal RX includes component RX1 and component RX2.
  • the component RX1 is generated based on the ultrasonic signal reflected on the surface of the subject.
  • the component RX2 is generated based on the ultrasonic signal reflected on the back surface of the subject.
  • the ultrasonic vibrator 10 outputs the echo signal RX to the pulse cutoff circuit 40.
  • the pulse cutoff circuit 40 removes the component RX1 from the echo signal RX.
  • the pulse cutoff circuit 40 does not remove the component RX2.
  • the component RX2 passes through the pulse cutoff circuit 40.
  • the pulse cutoff circuit 40 outputs an echo signal RXac including the component RX2 to the first amplifier 50.
  • the CPU 30 outputs the start pulse START to the first time measurement circuit 90 and the second time measurement circuit 100.
  • the time Tstoff may be set to 0.
  • the first comparator 70 generates the first measurement control signal STOP1 based on the component RX1, or the second comparator 80 is based on the component RX1.
  • the first time measurement circuit 90 and the second time measurement circuit 100 should not detect the first measurement control signal STOP1 and the second measurement control signal STOP2 generated based on the component RX1, respectively.
  • the time Tstoff prevents the first time measurement circuit 90 and the second time measurement circuit 100 from erroneously detecting the first measurement control signal STOP1 and the second measurement control signal STOP2 generated based on the component RX1. It is desirable to set.
  • the echo signal RXac is generated by removing the component RX1 and the DC component from the echo signal RX.
  • the first amplifier 50 generates the echo signal RXac1 by amplifying the echo signal RXac.
  • the second amplifier 60 generates the echo signal RXac2 by applying a signal corresponding to the change in the voltage of the echo signal RXac1 to the reference voltage Vcm and amplifying the echo signal RXac1.
  • the echo signal RXac2 has an amplitude on the positive side of the reference voltage Vcm and an amplitude on the negative side of the reference voltage Vcm.
  • the second amplifier 60 outputs the generated echo signal RXac2 to the first comparator 70 and the second comparator 80.
  • the first comparator 70 compares the voltage of the echo signal RXac2 with the first threshold THp.
  • the first threshold value THp is separated from the reference voltage Vcm by a predetermined value on the positive side.
  • the upward direction in FIG. 2 indicates the positive direction of the voltage. That is, the upward direction in FIG. 2 indicates the direction in which the voltage increases.
  • the second comparator 80 compares the voltage of the echo signal RXac2 with the second threshold THn.
  • the second threshold value THn is separated from the reference voltage Vcm by a predetermined value on the negative side.
  • the downward direction in FIG. 2 indicates the negative direction of the voltage. That is, the downward direction in FIG. 2 indicates the direction in which the voltage decreases.
  • the absolute value of the difference between the reference voltage Vcm and the first threshold value THp is the same as the absolute value of the difference between the reference voltage Vcm and the second threshold value THn. That is, the reference voltage Vcm is an intermediate voltage between the first threshold value THp and the second threshold value THn.
  • the absolute value of the difference between the reference voltage Vcm and the first threshold value THp may be different from the absolute value of the difference between the reference voltage Vcm and the second threshold value THn.
  • the first comparator 70 outputs a binary signal having a low level or a high level.
  • the first comparator 70 outputs the first measurement control signal STOP1 which is a low level.
  • the first comparator 70 outputs the first measurement control signal STOP1 which is a high level.
  • the second comparator 80 outputs a binary signal having a low level or a high level.
  • the second comparator 80 outputs the second measurement control signal STOP2 which is a low level.
  • the second comparator 80 outputs the second measurement control signal STOP2 which is a high level.
  • the first time measurement circuit 90 and the second time measurement circuit 100 start time measurement.
  • the first time measurement circuit 90 detects the rising edge of the first measurement control signal STOP1 or the falling edge of the first measurement control signal STOP1, and the first digital at the timing of the rising edge or the falling edge. Holds the value TDC1.
  • the first measurement control signal STOP1 changes from a low level to a high level
  • the first measurement control signal STOP1 rises.
  • the voltage of the first measurement control signal STOP1 changes from a high level to a low level
  • the first measurement control signal STOP1 falls.
  • the first time measurement circuit 90 measures the first time T1 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg4 of the first measurement control signal STOP1.
  • the first time measurement circuit 90 outputs the first digital value TDC1 indicating the first time T1 to the CPU 30.
  • the second time measurement circuit 100 detects the rising edge of the second measurement control signal STOP2 or the falling edge of the second measurement control signal STOP2, and the second digital at the timing of the rising edge or the falling edge. Holds the value TDC2.
  • the second measurement control signal STOP2 changes from a low level to a high level
  • the second measurement control signal STOP2 rises.
  • the second measurement control signal STOP2 changes from a high level to a low level
  • the second measurement control signal STOP2 falls.
  • the second time measurement circuit 100 measures the second time T2 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg3 of the second measurement control signal STOP2.
  • the second time measurement circuit 100 outputs a second digital value TDC2 indicating the second time T2 to the CPU 30.
  • the first time measurement circuit 90 can detect any one of the rising edge of the first measurement control signal STOP1 and the falling edge of the first measurement control signal STOP1.
  • the second time measurement circuit 100 can detect any one of the rising edge of the second measurement control signal STOP2 and the falling edge of the second measurement control signal STOP2.
  • FIG. 3 shows the waveform of each signal in the ultrasonic measuring device 1.
  • the waveforms of the start pulse START, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG.
  • the horizontal direction in FIG. 3 indicates time, and the vertical direction in FIG. 3 indicates the voltage of each signal.
  • the CPU 30 calculates the zero cross time T0 based on the first digital value TDC1 and the second digital value TDC2.
  • the first digital value TDC1 indicates a first time T1 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg4 of the first measurement control signal STOP1.
  • the second digital value TDC2 indicates the second time T2 from the timing tg2 to the timing tg3 of the rising edge of the second measurement control signal STOP2.
  • the zero cross time T0 indicates the time from the timing tg2 to the timing tg0.
  • Timing tg0 is the zero cross point.
  • the timing tg0 indicates the timing at which the voltage of the echo signal RXac2 reaches the reference voltage Vcm.
  • the timing tg0 is between the timing tg3 and the timing tg4.
  • the CPU 30 calculates the digital value Drx0 by calculating the average of the first digital value TDC1 and the second digital value TDC2 based on the following equation (5).
  • the digital value Drx0 corresponds to the zero cross time T0.
  • the CPU 30 determines the magnitude relationship between the reference voltage Vcm, the first threshold THp, and the second threshold THn.
  • the coefficient for weighting may be calculated based on this.
  • the CPU 30 may calculate the digital value Drx0 by using the first digital value TDC1, the second digital value TDC2, and the coefficients thereof.
  • the CPU 30 calculates the digital value Dtof by adding a predetermined digital value to the digital value Drx0.
  • the digital value Dtof indicates the time from the timing when the drive signal TX is output to the ultrasonic vibrator 10 to the timing when the echo signal RX (component RX2 shown in FIG. 2) is output from the ultrasonic vibrator 10.
  • the digital value Dtof indicates the time Ttof in the above-mentioned equations (1), (3), and (4).
  • the predetermined digital value indicates the time Tstoff shown in FIG.
  • the CPU 30 calculates the digital value Dtd by subtracting a predetermined digital value from the digital value Dtof.
  • the digital value Dtd indicates the time from the timing when the ultrasonic signal reaches the subject to the timing when the reflected signal reaches the ultrasonic vibrator 10.
  • the digital value Dtd indicates the time (Ttof-Toffset) in the above-mentioned equation (4).
  • the predetermined digital value indicates the offset time Toffset in the above-mentioned equations (3) and (4).
  • the CPU 30 calculates the thickness D of the subject based on the time indicated by the digital value Dtd, the speed of sound V corresponding to the material of the subject, and the equation (4).
  • the first comparator 70 changes the voltage of the first measurement control signal STOP1 to a high level or a low level every time the voltage of the echo signal RXac2 matches the first threshold value THp.
  • the second comparator 80 changes the voltage of the second measurement control signal STOP2 to a high level or a low level each time the voltage of the echo signal RXac2 matches the second threshold value THn.
  • the first time measurement circuit 90 may measure the first time only once, and the second time measurement circuit 100 may measure the second time twice or more.
  • the first time measuring circuit 90 may generate only one first digital value TDC1, and the second time measuring circuit 100 may generate two or more second digital values TDC2.
  • the first time measurement circuit 90 may measure the first time twice or more, and the second time measurement circuit 100 may measure the second time only once.
  • the first time measurement circuit 90 may generate two or more first digital values TDC1, and the second time measurement circuit 100 may generate only one second digital value TDC2.
  • the first time measurement circuit 90 may measure the first time twice or more, and the second time measurement circuit 100 may measure the second time twice or more.
  • the first time measurement circuit 90 may generate two or more first digital values TDC1
  • the second time measurement circuit 100 may generate two or more second digital values TDC2.
  • the number of digital values that the TDC circuit can hold is set when the TDC circuit is designed. As the number increases, the memory in the TDC circuit increases. For example, the number of digital values that the TDC circuit can hold is 5 or more and 10 or less.
  • FIG. 4 shows a waveform similar to the waveform of each signal shown in FIG.
  • the first comparator 70 outputs the first measurement control signal STOP1 which is a high level at each of the timing tg4, the timing tg6, and the timing tg8.
  • the second comparator 80 outputs a second measurement control signal STOP2 which is a high level at each of the timing tg3, the timing tg5, the timing tg7, and the timing tg9.
  • the first time measurement circuit 90 measures the first time T1a from the timing tg2 to the timing tg4, the first time T1b from the timing tg2 to the timing tg6, and the first time T1c from the timing tg2 to the timing tg8. do.
  • the first time measurement circuit 90 generates a first digital value TDC1 indicating each of the first time T1a, the first time T1b, and the first time T1c.
  • the first time measurement circuit 90 measures the first time three times and generates three first digital values TDC1.
  • the second time measurement circuit 100 includes a second time T2a from timing tg2 to timing tg3, a second time T2b from timing tg2 to timing tg5, a second time T2c from timing tg2 to timing tg7, and timing.
  • the second time T2d from tg2 to the timing tg9 is measured.
  • the second time measurement circuit 100 generates a second digital value TDC2 indicating each of the second time T2a, the second time T2b, the second time T2c, and the second time T2d.
  • the second time measurement circuit 100 measures the first time four times and generates four second digital values TDC2.
  • the CPU 30 sets the first digital value TDC1 and the second digital value TDC2 corresponding to the combination of the first time and the second time selected from two or more combinations of the first time and the second time.
  • the zero cross time may be calculated by use.
  • the CPU 30 calculates the zero cross time by using the following method.
  • the CPU 30 generates a combination including the first time and the second time closest to the first time.
  • the second time T2a is the closest to the first time T1a. Therefore, the CPU 30 generates a combination including the first time T1a and the second time T2a.
  • the second time T2b is the closest to the first time T1b. Therefore, the CPU 30 generates a combination including the first time T1b and the second time T2b.
  • the second time T2c is the closest to the first time T1c. Therefore, the CPU 30 generates a combination including the first time T1c and the second time T2c.
  • the CPU 30 may generate only combinations in which the absolute value of the difference between the first time and the second time is within a predetermined value. For example, the first time closest to the second time T2d is the first time T1c. The CPU 30 determines that the absolute value of the difference between the first time T1c and the second time T2d exceeds a predetermined value, and does not have to generate a combination including the second time T2d.
  • the CPU 30 selects the combination including the shortest time. For example, the CPU 30 selects a combination including the shortest first time T1a of the first time T1a, the first time T1b, and the first time T1c. Alternatively, the CPU 30 selects a combination that includes the shortest second time T2a of the second time T2a, the second time T2b, the second time T2c, and the second time T2d. Therefore, the CPU 30 selects a combination including the first time T1a and the second time T2a. The CPU 30 calculates the zero cross time by using the first digital value TDC1 corresponding to the first time T1a and the second digital value TDC2 corresponding to the second time T2a.
  • FIG. 5 shows the waveform of each signal in the ultrasonic measuring device 1.
  • the waveforms of the start pulse START, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG.
  • the horizontal direction in FIG. 5 indicates time, and the vertical direction in FIG. 5 indicates the voltage of each signal.
  • the ultrasonic measuring device 1 directly measures the time based on the echo signal of the ultrasonic signal without continuously performing AD conversion. If the echo signal contains noise, the ultrasonic measuring device 1 may not be able to accurately measure the time.
  • the echo signal RXac2 includes the noise N1 shown in FIG.
  • the first comparator 70 When the voltage of the noise N1 exceeds the first threshold value THp, the first comparator 70 generates the first measurement control signal STOP1 which is a high level.
  • the first time measurement circuit 90 measures the first time T1a based on the first measurement control signal STOP1 and outputs the first digital value TDC1 indicating the first time T1a to the CPU 30.
  • the CPU 30 uses this first digital value TDC1 to calculate the zero cross time, the CPU 30 calculates an erroneous thickness.
  • the ultrasonic measuring device 1 performs the following processing in order to avoid calculating an erroneous thickness.
  • the first comparator 70 changes the voltage of the first measurement control signal STOP1 to a high level or a low level every time the voltage of the echo signal RXac2 matches the first threshold value THp.
  • the second comparator 80 changes the voltage of the second measurement control signal STOP2 to a high level or a low level each time the voltage of the echo signal RXac2 matches the second threshold value THn.
  • the first time measurement circuit 90 measures the first time twice or more, or the second time measurement circuit 100 measures the second time twice or more.
  • the CPU 30 produces the first combination and the second combination by associating the first time and the second time with each other.
  • Each of the first combination and the second combination includes a first time and a second time. The first time of the first combination is different from the first time of the second combination, or the second time of the first combination is different from the second time of the second combination.
  • the CPU 30 calculates the first difference, which is the difference between the first time of the first combination and the second time of the first combination.
  • the CPU 30 calculates a second difference, which is the difference between the first time of the second combination and the second time of the second combination. If the absolute value of the first difference is smaller than the absolute value of the second difference, the CPU 30 calculates the zero cross time by using the first combination. If the absolute value of the second difference is smaller than the absolute value of the first difference, the CPU 30 calculates the zero cross time by using the second combination.
  • the first time measurement circuit 90 measures at least the first time T1a and the first time T1b.
  • the second time measurement circuit 100 measures at least the second time T2a.
  • the CPU 30 produces the first combination by associating the first time T1a and the second time T2a with each other.
  • the first combination includes a first time T1a and a second time T2a.
  • the CPU 30 produces a second combination by associating the first time T1b and the second time T2a with each other.
  • the second combination includes a first time T1b and a second time T2a.
  • the first time T1a of the first combination is different from the first time T1b of the second combination.
  • the CPU 30 calculates the first difference Tdiff1, which is the difference between the first time T1a and the second time T2a.
  • the CPU 30 calculates the second difference Tdiff2, which is the difference between the first time T1b and the second time T2a.
  • the absolute value of the second difference Tdiff2 is smaller than the absolute value of the first difference Tdiff1. Therefore, the CPU 30 calculates the zero cross time by using the first time T1b and the second time T2a included in the second combination. Since the CPU 30 does not use the first time T1a measured based on the noise N1, the ultrasonic measuring device 1 can reduce the time measurement error caused by the noise.
  • the CPU 30 may select the combination having the smallest absolute value of the difference between the first time and the second time. .. By using this method, the CPU 30 can avoid using the first time T1a as in the above example.
  • the echo signal RX, echo signal RXac, echo signal RXac1 and echo signal RXac2 are sine waves and have a period corresponding to the resonance frequency (drive frequency) of the ultrasonic vibrator 10. Therefore, the time from the timing when the voltage of the echo signal RXac2 shown in FIG. 5 exceeds the second threshold value THn to the timing when the voltage of the echo signal RXac2 exceeds the first threshold value THp is shorter than the predetermined time. That is, the difference between the first time and the second time is shorter than the predetermined time.
  • the predetermined time is 1/2 of the above cycle.
  • the CPU 30 may calculate the zero cross time by using the first time and the second time.
  • the predetermined value is set based on the resonance frequency of the ultrasonic vibrator 10.
  • FIG. 6 shows the waveform of each signal in the ultrasonic measuring device 1.
  • the waveforms of the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG.
  • the horizontal direction in FIG. 6 indicates time, and the vertical direction in FIG. 6 indicates the voltage of each signal.
  • FIG. 6 shows two examples in which the maximum amplitude of the echo signal RXac2 is different.
  • the maximum amplitude of the echo signal RXac2 in the first example is larger than the maximum amplitude of the echo signal RXac2 in the second example.
  • the first time measurement circuit 90 measures the first time T1a
  • the second time measurement circuit 100 measures the second time T2a.
  • the first time measurement circuit 90 measures the first time T1b
  • the second time measurement circuit 100 measures the second time T2b.
  • the amplitude of the echo signal RXac2 is generally smaller than the amplitude of the echo signal RXac2 in the first example. Since the rise of the first measurement control signal STOP1 in the second example is slower than the rise of the first measurement control signal STOP1 in the first example, the first time T1b in the second example is in the first example. It is larger than the first time T1a. Since the rise of the second measurement control signal STOP2 in the second example is earlier than the rise of the second measurement control signal STOP2 in the first example, the second time T2b in the second example is in the first example. It is smaller than the second time T2a.
  • the zero cross time which is the average of the first time T1a and the second time T2a in the first example, is the same as the zero cross time, which is the average of the first time T1b and the second time T2b in the second example. .. Therefore, even if the maximum amplitude of the echo signal RXac2 changes due to corrosion of the subject or the like, the CPU 30 can suppress the influence of the change and calculate the thickness of the subject with high accuracy. be able to.
  • the ultrasonic measuring device 1 of the first embodiment calculates the zero cross time based on the first time and the second time. Therefore, the ultrasonic measuring device 1 can perform time measurement using the ultrasonic signal with high accuracy. As a result, the ultrasonic measuring device 1 can calculate the thickness of the subject with high accuracy. The ultrasonic measuring device 1 can perform time measurement by using a simple configuration.
  • the ultrasonic measuring device 1 uses the combination in which the absolute value of the difference between the first time and the second time is small. By doing so, the zero cross time is calculated. Therefore, the ultrasonic measuring device 1 can reduce an error in time measurement caused by noise.
  • the first time measurement circuit 90 and the second time measurement circuit 100 are TDC circuits. Therefore, the power consumption of the ultrasonic measuring device 1 is reduced as compared with the power consumption of the device that continuously performs the AD conversion.
  • a modified example of the first embodiment of the present invention will be described. It is effective to adjust the gains of the first threshold value THp, the second threshold value THn, and the second amplifier 60 in order to reduce the time measurement error caused by noise.
  • the ultrasonic measuring device 1 does not have an ADC and does not monitor the amplitude of the echo signal RXac2. Therefore, it is difficult to adjust the gains of the first threshold value THp, the second threshold value THn, and the second amplifier 60.
  • the ultrasonic measuring device 1 has a function of adjusting the gains of the first threshold value THp, the second threshold value THn, and the second amplifier 60.
  • the CPU 30 changes the first threshold THp based on at least one of the first number and the second number, and the second number is based on at least one of the first number and the second number.
  • the threshold THn is changed.
  • the first number indicates the number of times that the first time measuring circuit 90 measures the first time.
  • the second number indicates the number of times that the second time measuring circuit 100 measures the second time.
  • the CPU 30 changes the gain of the second amplifier 60 based on at least one of the first number and the second number.
  • the first time measurement circuit 90 measures the first time three times and generates three first digital values TDC1.
  • the second time measurement circuit 100 measures the first time four times and generates four second digital values TDC2.
  • the number of the first digital value TDC1 is used as the first number.
  • the number of the second digital value TDC2 is used as the second number.
  • the CPU 30 increases the first threshold value THp and decreases the second threshold value THn. As a result, the difference between the first threshold value THp and the reference voltage becomes large, and the difference between the second threshold value THn and the reference voltage becomes large.
  • the CPU 30 decreases the first threshold value THp and increases the second threshold value THn. As a result, the difference between the first threshold value THp and the reference voltage becomes small, and the difference between the second threshold value THn and the reference voltage becomes small.
  • the CPU 30 changes the gain of the second amplifier 60.
  • the CPU 30 lowers the gain of the second amplifier 60.
  • the CPU 30 increases the gain of the second amplifier 60.
  • the CPU 30 changes the first threshold THp and the second threshold THn based on the first number and the second number.
  • the CPU 30 may change the first threshold THp based only on the first number or the second number.
  • the CPU 30 may change the second threshold THn based only on the first number or the second number.
  • the CPU 30 changes the gain of the second amplifier 60 based on the first number and the second number.
  • the CPU 30 may change the gain of the second amplifier 60 based only on the first number or the second number.
  • the CPU 30 may change the gain of the first amplifier 50 instead of the gain of the second amplifier 60.
  • the CPU 30 modifies the gains of the first threshold THp, the second threshold THn, and the second amplifier 60 based on at least one of the first number and the second number. do. Therefore, the ultrasonic measuring device 1 can reduce an error in time measurement caused by noise.
  • FIG. 7 shows the configuration of the ultrasonic measuring device 1a according to the second embodiment of the present invention.
  • the ultrasonic measuring device 1a shown in FIG. 7 includes an ultrasonic vibrator 10, a drive circuit 20, a CPU 30 (time calculation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a first comparator. It has 70, a second comparator 80, a time measuring circuit 90a, and a signal generation circuit 110.
  • the description of the same configuration as that shown in FIG. 1 will be omitted.
  • the first comparator 70 When the voltage of the echo signal RXac2 matches the first threshold value THp, the first comparator 70 outputs the first comparison signal COMP1 (first signal) indicating the first timing to the signal generation circuit 110. ..
  • the first comparison signal COMP1 is the same as the first measurement control signal STOP1 in the first embodiment.
  • the second comparator 80 When the voltage of the echo signal RXac2 matches the second threshold value THn, the second comparator 80 outputs the second comparison signal COMP2 (second signal) indicating the second timing to the signal generation circuit 110. ..
  • the second comparison signal COMP2 is the same as the second measurement control signal STOP2 in the first embodiment.
  • the signal generation circuit 110 generates a measurement control signal STOP (third signal) having a first edge and a second edge.
  • the first edge is synchronized with the first timing.
  • the second edge is synchronized with the second timing.
  • One of the first edge and the second edge is a rising edge.
  • the other of the first edge and the second edge is a falling edge.
  • When the first edge is the rising edge, the second edge is the falling edge.
  • the first edge is a falling edge
  • the second edge is a rising edge.
  • the signal generation circuit 110 outputs the generated measurement control signal STOP to the time measurement circuit 90a.
  • the time measurement circuit 90a is a TDC circuit.
  • the time measurement circuit 90a measures the first time from the start timing indicated by the start pulse START to the timing of the first edge of the measurement control signal STOP.
  • the time measurement circuit 90a generates and holds the first digital value TDC1 indicating the first time at the timing when the first edge appears in the measurement control signal STOP.
  • the time measurement circuit 90a outputs the generated first digital value TDC1 to the CPU 30.
  • the time measurement circuit 90a measures the second time from the start timing indicated by the start pulse START to the timing of the second edge of the measurement control signal STOP.
  • the time measurement circuit 90a generates and holds a second digital value TDC2 indicating the second time at the timing when the second edge appears in the measurement control signal STOP.
  • the time measurement circuit 90a outputs the generated second digital value TDC2 to the CPU 30.
  • FIG. 8 shows the waveform of each signal in the ultrasonic measuring device 1a.
  • the waveforms of the pulse TXpre, the drive signal TX, the start pulse START, the echo signal RXac2, the first comparison signal COMP1, the second comparison signal COMP2, and the measurement control signal STOP are shown in FIG.
  • the horizontal direction in FIG. 8 indicates time, and the vertical direction in FIG. 8 indicates the voltage of each signal. The description of the same operation as that shown in FIG. 2 will be omitted.
  • the first comparator 70 outputs a binary signal having a low level or a high level.
  • the first comparator 70 outputs the first comparison signal COMP1 which is a low level.
  • the first comparator 70 outputs the first comparison signal COMP1 which is a high level.
  • the second comparator 80 outputs a binary signal having a low level or a high level.
  • the second comparator 80 outputs the second comparison signal COMP2 which is a low level.
  • the second comparator 80 outputs the second comparison signal COMP2 which is a high level.
  • the signal generation circuit 110 changes the voltage of the measurement control signal STOP from low level to high level.
  • the measurement control signal STOP has a rising edge (second edge) synchronized with the rising edge of the second comparison signal COMP2.
  • the signal generation circuit 110 changes the voltage of the measurement control signal STOP from high level to low level.
  • the measurement control signal STOP has a falling edge (first edge) synchronized with the rising edge of the first comparison signal COMP1.
  • the first comparator 70 may output a signal obtained by inverting the first comparison signal COMP1 shown in FIG. 8 as the first comparator signal COMP1
  • the second comparator 80 may output a second comparison signal COMP1 shown in FIG.
  • a signal obtained by inverting the comparison signal COMP2 may be output as the second comparison signal COMP2.
  • the measurement control signal STOP has a rising edge synchronized with the falling edge of the second comparison signal COMP2 and has a falling edge synchronized with the falling edge of the first comparison signal COMP1.
  • the signal generation circuit 110 may generate a signal obtained by inverting the measurement control signal STOP shown in FIG. 8 as the measurement control signal STOP.
  • the measurement control signal STOP has a falling edge synchronized with the rising edge of the second comparison signal COMP2 and has a rising edge synchronized with the rising edge of the first comparison signal COMP1.
  • the time measurement circuit 90a When the start pulse START is output from the CPU 30, the time measurement circuit 90a starts measuring the time.
  • the time measurement circuit 90a detects the rising edge of the measurement control signal STOP and holds the second digital value TDC2 at the timing of the rising edge.
  • the time measurement circuit 90a measures the second time T2 from the timing tg2 of the rising edge of the start pulse START to the timing tg10 of the rising edge of the measurement control signal STOP.
  • the time measurement circuit 90a outputs a second digital value TDC2 indicating the second time T2 to the CPU 30.
  • the time measurement circuit 90a detects the falling edge of the measurement control signal STOP and holds the first digital value TDC1 at the timing of the falling edge. In the example shown in FIG. 8, the time measurement circuit 90a measures the first time T1 from the timing tg2 of the rising edge of the start pulse START to the timing tg11 of the falling edge of the measurement control signal STOP. The time measurement circuit 90a outputs the first digital value TDC1 indicating the first time T1 to the CPU 30.
  • the method by which the CPU 30 calculates the zero cross time and the thickness of the subject is the same as the method in the first embodiment.
  • the ultrasonic measuring device 1 of the first embodiment has a first time measuring circuit 90 and a second time measuring circuit 100.
  • the ultrasonic measuring device 1a of the second embodiment has a time measuring circuit 90a.
  • the number of time measuring circuits is reduced, which simplifies the system.
  • a third embodiment of the present invention will be described.
  • a cushioning material may be inserted between the ultrasonic transducer 10 and the subject.
  • a method called Echo-to-Echo measurement may be used. The principle of Echo-to-Echo measurement will be described with reference to FIG.
  • FIG. 9 shows the time for the ultrasonic signal to propagate.
  • a cross section of the ultrasonic vibrator 10, the subject 200, and the cushioning material 210 is shown.
  • the ultrasonic signal transmitted from the ultrasonic vibrator 10 is reflected on the surface (upper surface) of the subject and is received by the ultrasonic vibrator 10.
  • the time Ttof1 from the timing when the drive signal TX is output to the ultrasonic vibrator 10 to the timing when the echo signal RX is output from the ultrasonic vibrator 10 is expressed by the following equation (6).
  • Ttof1 Tm01 + Tm02 + Tm11 + Tm12 (6)
  • Time Ttof1 includes time Tm01, time Tm02, time Tm11, and time Tm12 in the formula (6).
  • the time Tm01 indicates the time from the timing when the drive signal TX is output to the ultrasonic vibrator 10 to the timing when the ultrasonic signal generated by the ultrasonic vibrator 10 reaches the cushioning material 210.
  • the time Tm02 indicates the time from the timing when the ultrasonic vibrator 10 receives the reflected signal from the surface of the subject 200 to the timing when the echo signal RX is output from the ultrasonic vibrator 10.
  • the time Tm11 indicates the time from the timing when the ultrasonic signal reaches the cushioning material 210 to the timing when the ultrasonic signal reaches the surface of the subject 200.
  • the time Tm12 indicates the time from the timing when the ultrasonic signal is reflected on the surface of the subject 200 to the timing when the reflected signal reaches the ultrasonic vibrator 10.
  • the ultrasonic signal transmitted from the ultrasonic vibrator 10 is reflected on the back surface (lower surface) of the subject and is received by the ultrasonic vibrator 10.
  • the time Ttof2 from the timing when the drive signal TX is output to the ultrasonic vibrator 10 to the timing when the echo signal RX is output from the ultrasonic vibrator 10 is expressed by the following equation (7).
  • Ttof2 Tm01 + Tm02 + Tm11 + Tm12 + Tm21 + Tm22 (7)
  • Time Ttof2 includes time Tm01, time Tm02, time Tm11, time Tm12, time Tm21, and time Tm22 in the formula (7).
  • the time Tm01, time Tm02, time Tm11, and time Tm12 in the formula (7) are the same as the time Tm01, time Tm02, time Tm11, and time Tm12 in the formula (6), respectively.
  • the time Tm21 indicates the time from the timing when the ultrasonic signal reaches the front surface of the subject 200 to the timing when the ultrasonic signal reaches the back surface of the subject 200.
  • the time Tm22 indicates the time from the timing when the ultrasonic signal is reflected on the back surface of the subject 200 to the timing when the reflected signal reaches the cushioning material 210.
  • the ultrasonic measuring device of the third embodiment measures the time Ttof1 and the time Ttof2, and calculates the difference between the time Ttof1 and the time Ttof2 to calculate the time for the ultrasonic signal to propagate in the subject 200. Can be obtained.
  • FIG. 10 shows the configuration of the ultrasonic measuring device 1b according to the third embodiment.
  • the ultrasonic measuring device 1b shown in FIG. 10 includes an ultrasonic vibrator 10, a drive circuit 20, a CPU 30b (time calculation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a first comparator. It has 70, a second comparator 80, a first time measuring circuit 90b, a second time measuring circuit 100b, and a signal generation circuit 110b.
  • the description of the same configuration as that shown in FIG. 1 will be omitted.
  • the CPU 30b generates a pulse TXpre and outputs the pulse TXpre to the drive circuit 20.
  • the first comparator 70 When the voltage of the echo signal RXac2 matches the first threshold value THp, the first comparator 70 outputs the first comparison signal COMP1 indicating the first timing to the signal generation circuit 110.
  • the first comparison signal COMP1 is the same as the first measurement control signal STOP1 in the first embodiment.
  • the second comparator 80 When the voltage of the echo signal RXac2 matches the second threshold value THn, the second comparator 80 outputs the second comparison signal COMP2 indicating the second timing to the signal generation circuit 110.
  • the second comparison signal COMP2 is the same as the second measurement control signal STOP2 in the first embodiment.
  • the first comparator 70 changes the voltage of the first comparator signal COMP1 to a high level or a low level each time the voltage of the echo signal RXac2 matches the first threshold value THp.
  • the second comparator 80 changes the voltage of the second comparator signal COMP2 to a high level or a low level each time the voltage of the echo signal RXac2 matches the second threshold value THn.
  • the signal generation circuit 110b generates the first measurement control signal STOP1 having the first edge and the second edge in the first period.
  • the first edge is synchronized with the first timing.
  • the second edge is synchronized with the second timing.
  • One of the first edge and the second edge is a rising edge.
  • the other of the first edge and the second edge is a falling edge.
  • the first edge is the rising edge
  • the second edge is the falling edge.
  • the first edge is a falling edge
  • the second edge is a rising edge.
  • the signal generation circuit 110b generates a second measurement control signal STOP2 having a third edge and a fourth edge in a second period after the first period.
  • the third edge synchronizes with the first timing.
  • the fourth edge synchronizes with the second timing.
  • One of the third edge and the fourth edge is a rising edge.
  • the other of the third edge and the fourth edge is a falling edge.
  • the third edge is the rising edge
  • the fourth edge is the falling edge.
  • the fourth edge is a rising edge.
  • time measurement is performed based on the echo signal RX of the ultrasonic signal reflected on the surface of the subject 200.
  • time measurement is performed based on the echo signal RX of the ultrasonic signal reflected on the back surface of the subject 200.
  • the signal generation circuit 110b switches between the operation in the first period and the operation in the second period based on the control signal SW output from the CPU 30b.
  • the CPU 30b generates a control signal SW at the timing when the first period and the second period are switched, and outputs the control signal SW to the signal generation circuit 110b. For example, first, the same time measurement as the time measurement in the second embodiment is performed. In this time measurement, the first time T1 and the second time T2 shown in FIG. 8 are measured. The CPU 30b may set the timing at which the first period and the second period are switched based on this result.
  • the signal generation circuit 110b Before the control signal SW is output from the CPU 30b, the signal generation circuit 110b generates the first measurement control signal STOP1 and outputs the first measurement control signal STOP1 to the first time measurement circuit 90b. After the control signal SW is output from the CPU 30b, the signal generation circuit 110b generates the second measurement control signal STOP2 and outputs the second measurement control signal STOP2 to the second time measurement circuit 100b.
  • the CPU 30b sets a start pulse START indicating the start timing of each of the first time measured by the first time measuring circuit 90b and the second time measured by the second time measuring circuit 100b to the first time measuring circuit 90b and the first time measuring circuit 90b. Output to the second time measurement circuit 100b.
  • the first time measurement circuit 90b and the second time measurement circuit 100b are TDC circuits.
  • the first time measurement circuit 90b measures the first time from the start timing indicated by the start pulse START to the timing of the first edge of the first measurement control signal STOP1.
  • the first time measurement circuit 90b generates and holds the first digital value TDC11 indicating the first time at the timing when the first edge appears in the first measurement control signal STOP1.
  • the first time measurement circuit 90b outputs the generated first digital value TDC 11 to the CPU 30.
  • the first time measurement circuit 90b measures the second time from the start timing indicated by the start pulse START to the timing of the second edge of the first measurement control signal STOP1.
  • the first time measurement circuit 90b generates and holds a second digital value TDC21 indicating the second time at the timing when the second edge appears in the first measurement control signal STOP1.
  • the first time measurement circuit 90b outputs the generated second digital value TDC 21 to the CPU 30.
  • the first time measurement circuit 90b measures the first time and the second time in the first period.
  • the first time measurement circuit 90b generates a first digital value TDC11 indicating a first time and a second digital value TDC21 indicating a second time in the first period.
  • the second time measurement circuit 100b measures the first time from the start timing indicated by the start pulse START to the timing of the third edge of the second measurement control signal STOP2.
  • the second time measurement circuit 100b generates and holds the first digital value TDC12 indicating the first time at the timing when the third edge appears in the second measurement control signal STOP2.
  • the second time measurement circuit 100b outputs the generated first digital value TDC 12 to the CPU 30.
  • the second time measurement circuit 100b measures the second time from the start timing indicated by the start pulse START to the timing of the fourth edge of the second measurement control signal STOP2.
  • the second time measurement circuit 100b generates and holds a second digital value TDC22 indicating the second time at the timing when the fourth edge appears in the second measurement control signal STOP2.
  • the second time measurement circuit 100b outputs the generated second digital value TDC 22 to the CPU 30.
  • the second time measurement circuit 100b measures the first time and the second time in the second period.
  • the second time measurement circuit 100b generates a first digital value TDC 12 indicating the first time and a second digital value TDC 22 indicating the second time in the second period.
  • the CPU 30b receives the first digital value TDC11 and the second digital value TDC21 output from the first time measurement circuit 90b, and the first digital value TDC12 and the first digital value TDC12 output from the second time measurement circuit 100b.
  • the second digital value TDC22 is received.
  • the CPU 30b calculates the first zero cross time based on the first digital value TDC 11 and the second digital value TDC 21.
  • the first zero cross time indicates the time from the start timing to the timing when the voltage of the echo signal RXac2 of the ultrasonic signal reflected on the surface of the subject 200 matches the reference voltage.
  • the CPU 30b calculates the second zero cross time based on the first digital value TDC12 and the second digital value TDC22.
  • the second zero cross time indicates the time from the start timing to the timing when the voltage of the echo signal RXac2 of the ultrasonic signal reflected on the back surface of the subject 200 matches the reference voltage.
  • the method of calculating the first zero crossing time and the second zero crossing time is the same as the method of calculating the zero crossing time in the first embodiment.
  • the CPU 30b calculates the thickness of the subject based on the difference between the first zero crossing time and the second zero crossing time. The difference corresponds to the difference between the time Ttof1 and the time Ttof2 in the equation (8).
  • FIG. 11 shows the waveform of each signal in the ultrasonic measuring device 1b.
  • the waveforms of the pulse TXpre, the drive signal TX, the start pulse START, the control signal SW, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG.
  • the horizontal direction in FIG. 11 indicates time, and the vertical direction in FIG. 11 indicates the voltage of each signal. The description of the same operation as that shown in FIG. 2 will be omitted.
  • the echo signal RXac2 includes the component RX3 and the component RX4.
  • the component RX3 is generated based on the ultrasonic signal reflected on the surface of the subject.
  • the component RX4 is generated based on the ultrasonic signal reflected on the back surface of the subject.
  • the maximum amplitude of the component RX4 is smaller than the maximum amplitude of the component RX3.
  • the CPU 30b outputs the pulse TXpre to the drive circuit 20 at the timing tg1.
  • the CPU 30b outputs the start pulse START to the first time measurement circuit 90b and the second time measurement circuit 100b.
  • the signal generation circuit 110b starts the output of the first measurement control signal STOP1.
  • the signal generation circuit 110b has stopped the output of the second measurement control signal STOP2.
  • the signal generation circuit 110b is based on the second comparison signal COMP2 output from the second comparator 80.
  • the voltage of the measurement control signal STOP1 of 1 is changed from a low level to a high level.
  • the first measurement control signal STOP1 has a rising edge (second edge) synchronized with the rising edge of the second comparison signal COMP2.
  • the signal generation circuit 110b is based on the first comparison signal COMP1 output from the first comparator 70.
  • the voltage of the measurement control signal STOP1 of 1 is changed from a high level to a low level.
  • the first measurement control signal STOP1 has a falling edge (first edge) synchronized with the rising edge of the first comparison signal COMP1.
  • the first time measurement circuit 90b When the start pulse START is output from the CPU 30b, the first time measurement circuit 90b starts measuring the time.
  • the first time measurement circuit 90b detects the rising edge of the first measurement control signal STOP1 and holds the second digital value TDC21 at the timing of the rising edge.
  • the first time measurement circuit 90b measures the second time T21 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg12 of the first measurement control signal STOP1.
  • the first time measurement circuit 90b outputs a second digital value TDC21 indicating the second time T21 to the CPU 30b.
  • the first time measurement circuit 90b detects the falling edge of the first measurement control signal STOP1 and holds the first digital value TDC11 at the timing of the falling edge. In the example shown in FIG. 11, the first time measurement circuit 90b measures the first time T11 from the timing tg2 of the rising edge of the start pulse START to the timing tg13 of the falling edge of the first measurement control signal STOP1. .. The first time measurement circuit 90b outputs the first digital value TDC11 indicating the first time T11 to the CPU 30b.
  • the CPU 30b outputs the control signal SW to the signal generation circuit 110b.
  • the signal generation circuit 110b stops the output of the first measurement control signal STOP1 and starts the output of the second measurement control signal STOP2.
  • the signal generation circuit 110b is based on the second comparison signal COMP2 output from the second comparator 80.
  • the voltage of the measurement control signal STOP2 of 2 is changed from a low level to a high level.
  • the second measurement control signal STOP2 has a rising edge (fourth edge) synchronized with the rising edge of the second comparison signal COMP2.
  • the signal generation circuit 110b is based on the first comparison signal COMP1 output from the first comparator 70.
  • the voltage of the measurement control signal STOP2 of 2 is changed from a high level to a low level.
  • the second measurement control signal STOP2 has a falling edge (third edge) synchronized with the rising edge of the first comparison signal COMP1.
  • the second time measurement circuit 100b detects the rising edge of the second measurement control signal STOP2 and holds the second digital value TDC22 at the timing of the rising edge. In the example shown in FIG. 11, the second time measurement circuit 100b measures the second time T22 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg15 of the second measurement control signal STOP2. The second time measurement circuit 100b outputs a second digital value TDC22 indicating the second time T22 to the CPU 30b.
  • the second time measurement circuit 100b detects the falling edge of the second measurement control signal STOP2, and holds the first digital value TDC12 at the timing of the falling edge.
  • the second time measurement circuit 100b measures the first time T12 from the timing tg2 of the rising edge of the start pulse START to the timing tg16 of the falling edge of the second measurement control signal STOP2. ..
  • the second time measurement circuit 100b outputs the first digital value TDC12 indicating the first time T12 to the CPU 30b.
  • the ultrasonic measuring device 1b may execute the Echo-to-Echo measurement twice or more. For example, after the first time measuring circuit 90b measures the time, the second time measuring circuit 100b measures the time. While the second time measurement circuit 100b is measuring the time, the CPU 30b reads the first digital value TDC11 and the second digital value TDC21 from the memory of the first time measurement circuit 90b. After the first digital value TDC11 and the second digital value TDC21 are read out, the first digital value TDC11 and the second digital value TDC21 in the memory of the first time measurement circuit 90b are erased.
  • the first time measurement circuit 90b measures the time again. While the first time measuring circuit 90b is measuring the time, the CPU 30b reads the first digital value TDC12 and the second digital value TDC22 from the memory of the second time measuring circuit 100b. After the first digital value TDC12 and the second digital value TDC22 are read out, the first digital value TDC12 and the second digital value TDC22 in the memory of the second time measurement circuit 100b are erased. The above operation is repeated.
  • the first time measurement circuit 90b measures the time based on the echo signal RXac2 (component RX3) of the ultrasonic signal reflected on the surface of the subject.
  • the second time measurement circuit 100b measures the time based on the echo signal RXac2 (component RX4) of the ultrasonic signal reflected on the back surface of the subject. Therefore, the ultrasonic measuring device 1b can perform Echo-to-Echo measurement.
  • the CPU 30b may change the gains of the first threshold value THp, the second threshold value THn, and the second amplifier 60 by using the same method as the method in the modified example of the first embodiment. Before the CPU 30b outputs the control signal SW, the CPU 30b has a first threshold THp, a second threshold THn, and a second amplifier based on the time measured by the first time measurement circuit 90b in the first period. The gain of 60 may be changed.
  • FIG. 12 shows an example of a situation in which a corrosion inspection is carried out.
  • the ultrasonic vibrator 10 is installed on the subject 220.
  • the subject 220 is a pipe made of metal.
  • the thickness of the subject 220 is D.
  • FIG. 13 shows the waveforms of the drive signal TX and the echo signal RX, respectively.
  • the horizontal direction in FIG. 13 indicates time, and the vertical direction in FIG. 13 indicates the voltage of each signal.
  • the thickness D of the subject 220 does not change, and the degree of unevenness on the surface of the subject 220 may increase due to corrosion. If the subject 220 is not corroded, the echo signal RX contains component RX5. If the subject 220 is corroded, the echo signal RX contains component RX6.
  • the pulse of the echo signal RX is output from the ultrasonic vibrator 10 at the timing tg17.
  • the timing at which the component RX 6 is output from the ultrasonic vibrator 10 is the same as the timing at which the component RX 5 is output from the ultrasonic vibrator 10.
  • the time for the ultrasonic signal to propagate in the subject 220 does not change regardless of whether the subject 220 is corroded or the subject 220 is not corroded. However, since the ultrasonic signal is diffused on the reflecting surface, the amplitude of the component RX6 is smaller than the amplitude of the component RX5. By detecting the change in the amplitude of the echo signal RX, the degree of corrosion of the subject 220 can be confirmed.
  • FIG. 14 shows the configuration of the ultrasonic measuring device 1c according to the fourth embodiment.
  • the ultrasonic measuring device 1c shown in FIG. 14 includes an ultrasonic transducer 10, a drive circuit 20, a CPU 30c (time calculation circuit, an amplitude estimation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a second amplifier. It has a comparator 70, a second comparator 80, a first time measuring circuit 90, and a second time measuring circuit 100. The description of the same configuration as that shown in FIG. 1 will be omitted.
  • the CPU 30c has the function of the CPU 30 shown in FIG. Further, the CPU 30c has a maximum amplitude of the echo signal RXac2 based on at least one of the first time measured by the first time measurement circuit 90 and the second time measured by the second time measurement circuit 100. To estimate.
  • the first time measurement circuit 90 outputs the first digital value TDC1 to the CPU 30c
  • the second time measurement circuit 100 outputs the second digital value TDC2 to the CPU 30c.
  • the CPU 30c estimates the maximum amplitude of the echo signal RXac2 based on at least one of the first digital value TDC1 and the second digital value TDC2.
  • the CPU 30c outputs the measured thickness value TMV and the estimated maximum amplitude value AMV to an external circuit.
  • FIG. 15 shows the waveform of the echo signal RXac2.
  • the horizontal axis in FIG. 15 indicates time, and the vertical axis in FIG. 15 indicates the voltage of the echo signal RXac2.
  • the echo signal RXac2 is a sine wave having the same frequency as the resonance frequency of the ultrasonic vibrator 10.
  • the amplitude V (t) of the echo signal RXac2 at time t is simply expressed by the following equation (9).
  • the amplitude V (t) is represented by the maximum amplitude A and the resonance frequency f of the ultrasonic vibrator 10.
  • the amplitude V (t) is represented as a sinusoidal curve.
  • V (t) A ⁇ sin (2 ⁇ ft) (9)
  • the change ⁇ V is the difference (THp ⁇ Vcm) between the first threshold value THp and the reference voltage Vcm.
  • the CPU 30c estimates the maximum amplitude A (first maximum amplitude) based on the difference (T1-T0), the difference (THp-Vcm), and the resonance frequency f of the ultrasonic transducer 10. Specifically, the CPU 30c calculates the difference between the first digital value TDC1 indicating the first time T1 and the digital value indicating the zero cross time T0. The CPU 30c uses the difference in digital values as the difference (T1-T0).
  • the change ⁇ V is the difference (Vcm-THn) between the second threshold value THn and the reference voltage Vcm.
  • the CPU 30c may estimate the maximum amplitude A (second maximum amplitude) based on the difference (T0-T2), the difference (Vcm-THn), and the resonance frequency f of the ultrasonic transducer 10. In this case, the CPU 30c uses the difference between the second digital value TDC2 indicating the second time T2 and the digital value indicating the zero cross time T0 as the difference (T0-T2).
  • the CPU 30c may calculate the average of the first maximum amplitude and the second maximum amplitude described above.
  • the CPU 30c may output the calculated average as the maximum amplitude value AMV.
  • the CPU 30c may estimate the first amplitude, which is the maximum amplitude of the echo signal RXac2.
  • the CPU 30c may estimate the second amplitude, which is the maximum amplitude of the echo signal RXac2. ..
  • the CPU 30c corrosion estimation circuit
  • the CPU 30c may estimate the degree of corrosion of the subject based on the first amplitude and the second amplitude.
  • the CPU 30c may calculate the ratio of the first amplitude to the second amplitude (second amplitude / first amplitude) and estimate the degree of corrosion based on the ratio. For example, the CPU 30c may compare the ratio with a predetermined threshold (eg, 0.9). When the ratio is equal to or higher than a predetermined threshold value, the CPU 30c may determine that the subject is not corroded. If the ratio is smaller than a predetermined threshold, the CPU 30c may determine that the subject is corroded.
  • a predetermined threshold eg, 0.9
  • the CPU 30c estimates the maximum amplitude of the echo signal RXac2 based on at least one of the first time and the second time. Therefore, the ultrasonic measuring device 1c can measure the thickness of the subject and the maximum amplitude of the echo signal RXac2 without continuously performing the AD conversion.
  • FIG. 16 shows the waveform of the echo signal RXac2.
  • the horizontal axis in FIG. 16 indicates time, and the vertical axis in FIG. 16 indicates the voltage of the echo signal RXac2.
  • the straight line L1 indicates the slope of the echo signal RXac2 at the zero cross point (end timing of the zero cross time T0) when the echo signal RXac2 has the maximum amplitude A.
  • the straight line L2 indicates the slope of the echo signal RXac2 at the zero crossing point when the echo signal RXac2 has the maximum amplitude A / 2.
  • the slope of the straight line L2 is smaller than the slope of the straight line L1. As the maximum amplitude of the echo signal RXac2 decreases, the slope of the echo signal RXac2 at the zero cross point decreases.
  • the CPU 30c calculates the slope Slope0 of the echo signal RXac2 at the zero crossing point according to the following equation (12).
  • the CPU 30c uses the difference between the first digital value TDC1 indicating the first time T1 and the second digital value TDC2 indicating the second time T2 as the difference (T1-T2).
  • Slope0 (THp-THn) / (T1-T2) (12)
  • the CPU 30c converts the slope Slope 0 to the maximum amplitude. For example, a coefficient indicating the relationship between the slope Slope 0 and the maximum amplitude is stored in the memory in advance. The CPU 30c calculates the maximum amplitude by using the slope Slope 0 and its coefficient.
  • the time-series change of the slope Slope0 corresponds to the time-series change of the maximum amplitude.
  • the CPU 30c may output the slope Slope 0 to an external circuit without calculating the maximum amplitude.
  • FIG. 17 shows the configuration of the ultrasonic measuring device 1d of the second modification of the fourth embodiment.
  • the ultrasonic measuring device 1d shown in FIG. 17 includes an ultrasonic transducer 10, a drive circuit 20, a CPU 30d (time calculation circuit, an amplitude estimation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a second amplifier. It has a comparator 70, a second comparator 80, a first time measuring circuit 90d, a second time measuring circuit 100d, and a memory 120. The description of the same configuration as that shown in FIG. 1 will be omitted.
  • the memory 120 was obtained through machine learning that uses the first time, the second time, the first threshold THp, and the second threshold THn as input data, and obtains the amplitude of the echo signal RXac2 as correct data. Memorize the learning model.
  • the CPU 30d has the function of the CPU 30 shown in FIG. Further, the CPU 30d has a function of estimating the waveform of the echo signal RXac2. The CPU 30d estimates the maximum amplitude of the echo signal RXac2 based on the first time, the second time, the first threshold THp, and the second threshold THn by using the learning model stored in the memory 120. do. The CPU 30d outputs the measured thickness value TMV and the estimated maximum amplitude value AMV to an external circuit.
  • the first time measurement circuit 90d and the second time measurement circuit 100d are TDC circuits.
  • the first time measurement circuit 90d measures the first time from the start timing indicated by the start pulse START to the first timing indicated by the first measurement control signal STOP1.
  • the first timing includes the timing of the rising edge of the first measurement control signal STOP1 and the timing of the falling edge of the first measurement control signal STOP1. Therefore, the first time includes two kinds of time.
  • the first time measurement circuit 90d measures the time from the start timing to the timing of the rising edge of the first measurement control signal STOP1, and from the start timing to the falling edge of the first measurement control signal STOP1. Measure the time to the timing.
  • the first time measurement circuit 90d generates and holds a first digital value TDC1 indicating each of the two types of first time.
  • the first time measurement circuit 90d outputs the generated first digital value TDC1 to the CPU 30d.
  • the second time measurement circuit 100d measures the second time from the start timing indicated by the start pulse START to the second timing indicated by the second measurement control signal STOP2.
  • the second timing includes the timing of the rising edge of the second measurement control signal STOP2 and the timing of the falling edge of the second measurement control signal STOP2. Therefore, the second time includes two kinds of time.
  • the second time measurement circuit 100d measures the time from the start timing to the timing of the rising edge of the second measurement control signal STOP2, and from the start timing to the falling edge of the second measurement control signal STOP2. Measure the time to the timing.
  • the second time measurement circuit 100d generates and holds a second digital value TDC2 indicating each of the two types of second time.
  • the second time measurement circuit 100d outputs the generated second digital value TDC2 to the CPU 30d.
  • FIG. 18 shows the waveform of each signal in the ultrasonic measuring device 1d.
  • the waveforms of the pulse TXpre, the drive signal TX, the start pulse START, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG.
  • the horizontal direction in FIG. 18 indicates time, and the vertical direction in FIG. 18 indicates the voltage of each signal. The description of the same operation as that shown in FIG. 2 will be omitted.
  • the CPU 30d outputs the pulse TXpre to the drive circuit 20 at the timing tg1. At the timing tg2 in which the predetermined time Tstoff has elapsed from the timing tg1, the CPU 30d outputs the start pulse START to the first time measurement circuit 90d and the second time measurement circuit 100d.
  • the first comparator 70 When the voltage of the echo signal RXac2 is smaller than the first threshold value THp, the first comparator 70 outputs the first measurement control signal STOP1 which is a low level. When the voltage of the echo signal RXac2 is equal to or higher than the first threshold value THp, the first comparator 70 outputs the first measurement control signal STOP1 which is a high level.
  • the second comparator 80 When the voltage of the echo signal RXac2 is smaller than the second threshold value THn, the second comparator 80 outputs the second measurement control signal STOP2 which is a low level. When the voltage of the echo signal RXac2 is equal to or higher than the second threshold value THn, the second comparator 80 outputs the second measurement control signal STOP2 which is a high level.
  • the first time measurement circuit 90d and the second time measurement circuit 100d start measuring the time.
  • the first time measurement circuit 90d detects each of the rising edge of the first measurement control signal STOP1 and the falling edge of the first measurement control signal STOP1, and sets the first digital value TDC1 at the timing of each edge. Hold.
  • the second time measurement circuit 100d detects each of the rising edge of the second measurement control signal STOP2 and the falling edge of the second measurement control signal STOP2, and sets the second digital value TDC2 at the timing of each edge. Hold.
  • the second time measurement circuit 100d sets the second time T21 from the timing tg2 of the rising edge of the start pulse START to the timing of the first falling edge of the second measurement control signal STOP2. measure.
  • the second time measurement circuit 100d measures the second time T22 from the timing tg2 to the timing of the first rising edge of the second measurement control signal STOP2.
  • the second time measurement circuit 100d measures the second time T23 from the timing tg2 to the timing of the second falling edge of the second measurement control signal STOP2.
  • the second time measurement circuit 100d measures the second time T24 from the timing tg2 to the timing of the second rising edge of the second measurement control signal STOP2.
  • the second time measurement circuit 100d outputs a second digital value TDC2 indicating each of the second time T21, the second time T22, the second time T23, and the second time T24 to the CPU 30d.
  • the second measurement control signal STOP2 falls for the third time
  • the second measurement control signal STOP2 rises for the third time
  • the second measurement control signal STOP2 falls for the fourth time.
  • the second time is also measured at the fourth rise of the second measurement control signal STOP2.
  • the description of the second digital value TDC2 corresponding to the second time measured at these timings will be omitted.
  • the first time measurement circuit 90d measures the first time T11 from the timing tg2 of the rising edge of the start pulse START to the timing of the first rising edge of the first measurement control signal STOP1. do.
  • the first time measurement circuit 90d measures the first time T12 from the timing tg2 to the timing of the first falling edge of the first measurement control signal STOP1.
  • the first time measurement circuit 90d measures the first time T13 from the timing tg2 to the timing of the second rising edge of the first measurement control signal STOP1.
  • the first time measurement circuit 90d measures the first time T14 from the timing tg2 to the timing of the second falling edge of the first measurement control signal STOP1.
  • the first time measurement circuit 90d outputs a first digital value TDC1 indicating each of the first time T11, the first time T12, the first time T13, and the first time T14 to the CPU 30d.
  • the first time measurement circuit 90d also measures the first time at the third rise of the first measurement control signal STOP1 and the third fall of the first measurement control signal STOP1.
  • the description of the first digital value TDC1 corresponding to the first time measured at these timings will be omitted.
  • FIG. 19 shows the relationship between each first time, each second time, the first threshold THp, and the second threshold THn.
  • the CPU 30d associates the first digital value TDC1 indicating each first time, the second digital value TDC2 indicating each second time, the first threshold value THp, and the second threshold value THn with each other. Further, the CPU 30d calculates the equation (correct answer data) of the curve L3 showing the amplitude of the echo signal RXac2 by using these values and using deep learning or the like.
  • the CPU 30d generates a learning model including a first digital value TDC1, a second digital value TDC2, a first threshold THp, a second threshold THn, and a curve equation.
  • the CPU 30d stores the learning model in the memory 120.
  • the ultrasonic measuring device 1d repeats learning including the above operation and updates the learning model. For example, the ultrasonic measuring device 1d repeats learning by repeatedly transmitting an ultrasonic signal to the same subject. Alternatively, the ultrasonic measuring device 1d changes the subject each time the learning is executed one or more times, and repeats the learning.
  • An external ultrasonic measuring device having the same configuration as that of the ultrasonic measuring device 1d may execute the above learning and generate a learning model.
  • the ultrasonic measuring device 1d may perform communication with an external ultrasonic measuring device and receive a learning model.
  • the inspection will be carried out.
  • An operation similar to the operation shown in FIG. 18 is executed, and the CPU 30d receives the first digital value TDC1 and the second digital value TDC2.
  • the CPU 30d reads the learning model from the memory 120.
  • the CPU 30d has a first digital value TDC1 obtained in the test, a second digital value TDC2 obtained in the test, a first threshold value THp used in the test, and a second threshold value used in the test.
  • the maximum amplitude of the echo signal RXac2 is estimated based on THn and the learning model.
  • the ultrasonic measuring device 1d may use four threshold values instead of the two threshold values. In the following, an example in which the ultrasonic measuring device 1d has four comparators and four time measuring circuits will be described.
  • the four comparators have a first comparator, a second comparator, a third comparator, and a fourth comparator.
  • the first comparator compares the voltage of the echo signal RXac2 with the first threshold value THp1 on the positive side of the reference voltage. When the voltage of the echo signal RXac2 matches the first threshold value THp1, the first comparator outputs the first measurement control signal indicating the first timing.
  • the second comparator compares the voltage of the echo signal RXac2 with the second threshold THn2 on the negative side of the reference voltage. When the voltage of the echo signal RXac2 coincides with the second threshold value THn2, the second comparator outputs a second measurement control signal indicating the second timing.
  • the third comparator compares the voltage of the echo signal RXac2 with the third threshold value THp3 on the positive side of the reference voltage. When the voltage of the echo signal RXac2 matches the third threshold value THp3, the third comparator outputs a third measurement control signal indicating the third timing.
  • the fourth comparator compares the voltage of the echo signal RXac2 with the fourth threshold THn4 on the negative side of the reference voltage. When the voltage of the echo signal RXac2 coincides with the fourth threshold value THn4, the fourth comparator outputs a fourth measurement control signal indicating the fourth timing.
  • FIG. 20 shows the relationship between the first threshold value THp1, the second threshold value THn2, the third threshold value THp3, and the fourth threshold value THn4.
  • the third threshold THp3 is smaller than the first threshold THp1.
  • the fourth threshold THn4 is larger than the second threshold THn2.
  • the four time measurement circuits include a first time measurement circuit, a second time measurement circuit, a third time measurement circuit, and a fourth time measurement circuit.
  • the first time measurement circuit measures the first time from the start timing indicated by the start pulse START to the first timing indicated by the first measurement control signal.
  • the second time measurement circuit measures the second time from the start timing to the second timing indicated by the second measurement control signal.
  • the third time measurement circuit measures the third time from the start timing to the third timing indicated by the third measurement control signal.
  • the fourth time measurement circuit measures the fourth time from the start timing to the fourth timing indicated by the fourth measurement control signal.
  • the CPU 30d may generate a learning model by executing machine learning using digital values indicating the first to fourth times and the first to fourth threshold values. By using this learning model, the CPU 30d can estimate the amplitude of the echo signal RXac2 with high accuracy.
  • the ultrasonic measuring device 1d may change the first threshold value THp of the first comparator 70 and the second threshold value THn of the second comparator 80, and may repeat the learning. Specifically, the first threshold value THp1 shown in FIG. 20 is set in the first comparator 70, the second threshold value THn2 shown in FIG. 20 is set in the second comparator 80, and the ultrasonic measuring device. 1d executes the first learning. In the first learning, the first time measuring circuit 90 measures the first time, and the second time measuring circuit 100 measures the second time.
  • the third threshold value THp3 shown in FIG. 20 is set in the first comparator 70
  • the fourth threshold value THn4 shown in FIG. 20 is set in the second comparator 80
  • the ultrasonic measuring device 1d is set to 2.
  • the first time measuring circuit 90 measures the third time
  • the second time measuring circuit 100 measures the fourth time.
  • the CPU 30d can obtain a digital value indicating the first to fourth times.
  • the CPU 30d estimates the maximum amplitude of the echo signal RXac2 by using a learning model obtained through machine learning. Therefore, the ultrasonic measuring device 1d can estimate the maximum amplitude of the echo signal RXac2 with high accuracy.
  • the ultrasonic measuring device can perform time measurement using an ultrasonic signal with high accuracy.

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Abstract

This ultrasonic measurement device comprises an ultrasonic oscillator, a first comparator, a second comparator, a time measurement circuit, and a time calculation circuit. The ultrasonic oscillator transmits an ultrasonic signal to a subject and generates an echo signal. The first comparator compares the voltage of the echo signal and a first threshold. The second comparator compares the voltage of the echo signal and a second threshold. The time measurement circuit measures a first period of time from a starting point in time to a first point in time and measures a second period of time from the starting point in time to a second point in time. The time calculation circuit uses the first period of time and the second period of time to calculate the period of time from the starting point in time until a zero crossing.

Description

超音波計測装置Ultrasonic measuring device
　本発明は、超音波計測装置に関する。 The present invention relates to an ultrasonic measuring device.
　図２１は、従来技術の超音波計測装置１００１の構成を示す。図２１に示す超音波計測装置１００１は、超音波振動子１０１０、駆動回路１０２０、ＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）１０３０、パルス遮断回路１０４０、第１の増幅器１０５０、第２の増幅器１０６０、およびＡＤＣ（Ａｎａｌｏｇ－ｔｏ－Ｄｉｇｉｔａｌ　Ｃｏｎｖｅｒｔｅｒ）１０７０を有する。 FIG. 21 shows the configuration of the conventional ultrasonic measuring device 1001. The ultrasonic measuring device 1001 shown in FIG. 21 includes an ultrasonic vibrator 1010, a drive circuit 1020, a CPU (Central Processing Unit) 1030, a pulse cutoff circuit 1040, a first amplifier 1050, a second amplifier 1060, and an ADC (Analog). -To-Digital Controller) 1070.
　ＣＰＵ１０３０は、パルスＴＸｐｒｅを生成し、かつパルスＴＸｐｒｅを駆動回路１０２０に出力する。駆動回路１０２０は、パルスＴＸｐｒｅを受信したタイミングで駆動信号ＴＸを生成し、かつ駆動信号ＴＸを超音波振動子１０１０に出力する。超音波振動子１０１０は、圧電素子である。超音波振動子１０１０は、駆動信号ＴＸに基づいて超音波信号を生成し、かつ超音波信号を測定対象である被検体に照射する。 The CPU 1030 generates a pulse TXpre and outputs the pulse TXpre to the drive circuit 1020. The drive circuit 1020 generates a drive signal TX at the timing of receiving the pulse TXpre, and outputs the drive signal TX to the ultrasonic vibrator 1010. The ultrasonic vibrator 1010 is a piezoelectric element. The ultrasonic vibrator 1010 generates an ultrasonic signal based on the drive signal TX, and irradiates the subject to be measured with the ultrasonic signal.
　被検体に照射された超音波信号は、被検体の境界面で反射する。被検体の境界面で反射した超音波信号（反射信号）は超音波振動子１０１０に入射する。超音波振動子１０１０は、反射信号を受信し、かつ反射信号に基づいてエコー信号ＲＸを生成する。超音波振動子１０１０は、生成されたエコー信号ＲＸをパルス遮断回路１０４０に出力する。パルス遮断回路１０４０は、不要な信号成分を遮断することによりエコー信号ＲＸからその信号成分を除去する。パルス遮断回路１０４０は、不要な信号成分が除去されたエコー信号ＲＸａｃを第１の増幅器１０５０に出力する。 The ultrasonic signal applied to the subject is reflected at the interface of the subject. The ultrasonic signal (reflected signal) reflected at the interface of the subject is incident on the ultrasonic vibrator 1010. The ultrasonic vibrator 1010 receives the reflected signal and generates an echo signal RX based on the reflected signal. The ultrasonic vibrator 1010 outputs the generated echo signal RX to the pulse cutoff circuit 1040. The pulse cutoff circuit 1040 removes the signal component from the echo signal RX by cutting off an unnecessary signal component. The pulse cutoff circuit 1040 outputs the echo signal RXac from which unnecessary signal components have been removed to the first amplifier 1050.
　第１の増幅器１０５０は、ＬＮＡ（Ｌｏｗ　Ｎｏｉｓｅ　Ａｍｐｌｉｆｉｅｒ）である。第１の増幅器１０５０は、エコー信号ＲＸａｃを固定されたゲインで増幅することによりエコー信号ＲＸａｃ１を生成する。第１の増幅器１０５０は、エコー信号ＲＸａｃに与えるノイズが最小限になるようにエコー信号ＲＸａｃ１を生成する。第１の増幅器１０５０は、生成されたエコー信号ＲＸａｃ１を第２の増幅器１０６０に出力する。第２の増幅器１０６０は、ＰＧＡ（Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｉｎ　Ａｍｐｌｉｆｉｅｒ）である。第２の増幅器１０６０は、エコー信号ＲＸａｃ１を予め設定されたゲインで増幅することによりエコー信号ＲＸａｃ２を生成する。第２の増幅器１０６０は、生成されたエコー信号ＲＸａｃ２をＡＤＣ１０７０に出力する。 The first amplifier 1050 is an LNA (Low Noise Amplifier). The first amplifier 1050 generates the echo signal RXac1 by amplifying the echo signal RXac with a fixed gain. The first amplifier 1050 generates the echo signal RXac1 so as to minimize the noise given to the echo signal RXac. The first amplifier 1050 outputs the generated echo signal RXac1 to the second amplifier 1060. The second amplifier 1060 is a PGA (Programable Gain Amplifier). The second amplifier 1060 generates the echo signal RXac2 by amplifying the echo signal RXac1 with a preset gain. The second amplifier 1060 outputs the generated echo signal RXac2 to the ADC 1070.
　ＡＤＣ１０７０は、アナログのエコー信号ＲＸａｃ２にＡＤ変換を実施することによりデジタルのエコー信号ＲＸｄを生成する。ＡＤＣ１０７０は、生成されたエコー信号ＲＸｄをＣＰＵ１０３０に出力する。ＣＰＵ１０３０は、パルスＴＸｐｒｅおよびエコー信号ＲＸｄの各々のタイミングを使用することにより、駆動信号ＴＸが超音波振動子１０１０に出力されたタイミングと、エコー信号ＲＸが超音波振動子１０１０から出力されたタイミングとの差を算出する。ＣＰＵ１０３０は、算出された差に基づいて被検体の厚さを算出する。 The ADC 1070 generates a digital echo signal RXd by performing AD conversion on the analog echo signal RXac2. The ADC 1070 outputs the generated echo signal RXd to the CPU 1030. The CPU 1030 uses the timings of the pulse TXpre and the echo signal RXd to determine the timing at which the drive signal TX is output to the ultrasonic vibrator 1010 and the timing at which the echo signal RX is output from the ultrasonic vibrator 1010. Calculate the difference between. The CPU 1030 calculates the thickness of the subject based on the calculated difference.
　超音波信号のエコー信号に基づいて時間を直接的かつ簡易に計測し、かつその時間に基づいて被検体の厚さを算出する装置が特許文献１に開示されている。その装置は、比較器およびカウンタを使用することにより、エコー信号の電圧が所定電圧を超えるまでの時間を計測する。その装置は、計測された時間に基づいて被検体の厚さを算出する。 Patent Document 1 discloses an apparatus that directly and easily measures the time based on the echo signal of the ultrasonic signal and calculates the thickness of the subject based on the time. The device uses a comparator and a counter to measure the time it takes for the voltage of the echo signal to exceed a predetermined voltage. The device calculates the thickness of the subject based on the measured time.
　図２２は、超音波信号が伝搬する時間を示す。図２２において、超音波振動子１０１０および被検体１２００の断面が示されている。駆動信号ＴＸが超音波振動子１０１０に出力されたタイミングからエコー信号ＲＸが超音波振動子１０１０から出力されたタイミングまでの時間Ｔｔｏｆは以下の式（１）で表される。
　　Ｔｔｏｆ＝Ｔｍ０１＋Ｔｍ０２＋Ｔｍ１１＋Ｔｍ１２　　（１） FIG. 22 shows the time for the ultrasonic signal to propagate. In FIG. 22, a cross section of the ultrasonic vibrator 1010 and the subject 1200 is shown. The time Ttof from the timing when the drive signal TX is output to the ultrasonic vibrator 1010 to the timing when the echo signal RX is output from the ultrasonic vibrator 1010 is expressed by the following equation (1).
Ttof = Tm01 + Tm02 + Tm11 + Tm12 (1)
　時間Ｔｔｏｆは、式（１）における時間Ｔｍ０１、時間Ｔｍ０２、時間Ｔｍ１１、および時間Ｔｍ１２を含む。時間Ｔｍ０１は、駆動信号ＴＸが超音波振動子１０１０に出力されたタイミングから、超音波振動子１０１０によって生成された超音波信号が被検体１２００に到達するタイミングまでの時間を示す。時間Ｔｍ０２は、超音波振動子１０１０が反射信号を受信したタイミングからエコー信号ＲＸが超音波振動子１０１０から出力されたタイミングまでの時間を示す。時間Ｔｍ１１は、超音波信号が被検体１２００の表面（上面）に到達したタイミングから超音波信号が被検体１２００の裏面（下面）に到達するタイミングまでの時間を示す。時間Ｔｍ１２は、超音波信号が被検体１２００の裏面で反射したタイミングから反射信号が超音波振動子１０１０に到達するタイミングまでの時間を示す。 The time Ttof includes the time Tm01, the time Tm02, the time Tm11, and the time Tm12 in the formula (1). The time Tm01 indicates the time from the timing when the drive signal TX is output to the ultrasonic vibrator 1010 to the timing when the ultrasonic signal generated by the ultrasonic vibrator 1010 reaches the subject 1200. The time Tm02 indicates the time from the timing when the ultrasonic vibrator 1010 receives the reflected signal to the timing when the echo signal RX is output from the ultrasonic vibrator 1010. The time Tm11 indicates the time from the timing when the ultrasonic signal reaches the front surface (upper surface) of the subject 1200 to the timing when the ultrasonic signal reaches the back surface (lower surface) of the subject 1200. The time Tm12 indicates the time from the timing when the ultrasonic signal is reflected on the back surface of the subject 1200 to the timing when the reflected signal reaches the ultrasonic vibrator 1010.
　時間Ｔｍ１１と時間Ｔｍ１２との和（Ｔｍ１１＋Ｔｍ１２）は、被検体の厚さＤと、材料に応じた音速Ｖとに基づいて決定される。その和は以下の式（２）で表される。
　　Ｔｍ１１＋Ｔｍ１２＝２×Ｄ／Ｖ　　（２） The sum of the time Tm11 and the time Tm12 (Tm11 + Tm12) is determined based on the thickness D of the subject and the speed of sound V depending on the material. The sum is expressed by the following equation (2).
Tm11 + Tm12 = 2 × D / V (2)
　時間Ｔｍ０１と時間Ｔｍ０２との和（Ｔｍ０１＋Ｔｍ０２）は、システムに固有の固定されたオフセット時間Ｔｏｆｆｓｅｔである。したがって、時間Ｔｔｏｆは以下の式（３）で表される。
　　Ｔｔｏｆ＝Ｔｍ０１＋Ｔｍ０２＋Ｔｍ１１＋Ｔｍ１２＝Ｔｏｆｆｓｅｔ＋２×Ｄ／Ｖ　　（３） The sum of time Tm01 and time Tm02 (Tm01 + Tm02) is a system-specific fixed offset time Toffset. Therefore, the time Ttof is expressed by the following equation (3).
Ttof = Tm01 + Tm02 + Tm11 + Tm12 = Toffset + 2 × D / V (3)
　厚さＤは、以下の式（４）で表される。つまり、厚さＤは、システムに固有の既知のオフセット時間Ｔｏｆｆｓｅｔと、材料に応じた音速Ｖと、計測された時間Ｔｔｏｆとに基づいて算出される。
　　Ｄ＝（Ｔｔｏｆ－Ｔｏｆｆｓｅｔ）×Ｖ／２　　（４） The thickness D is represented by the following formula (4). That is, the thickness D is calculated based on the system-specific known offset time Toffset, the speed of sound V depending on the material, and the measured time Ttof.
D = (Ttof-Toffset) x V / 2 (4)
日本国特開昭６３－３０９８０８号公報Japanese Patent Application Laid-Open No. 63-309808
　鋼鉄の厚さを０．０１ｍｍの分解能で計測する場合がある。その場合、鋼鉄における音速（約６０００ｍ／ｓ）に対応する３．３３ｎｓ程度の時間分解能が必要である。図２１に示す超音波計測装置１００１のようにＡＤ変換を連続的に実施するシステムにおいて、アナログ信号を常にデジタル信号に変換する必要がある。そのため、サンプリング周波数が高く、かつ消費電力が大きい。 The thickness of steel may be measured with a resolution of 0.01 mm. In that case, a time resolution of about 3.33 ns corresponding to the speed of sound (about 6000 m / s) in steel is required. In a system that continuously performs AD conversion such as the ultrasonic measuring device 1001 shown in FIG. 21, it is necessary to always convert an analog signal into a digital signal. Therefore, the sampling frequency is high and the power consumption is high.
　特許文献１に開示された装置はＡＤ変換を連続的に実施する必要がないため、その装置の構成は簡易であり、かつ消費電力は低減される。一方、その装置において、被検体の腐食等の理由でエコー信号の振幅が変化すると、エコー信号の電圧が比較器の閾値に到達するタイミングが変化する。その結果、計測された被検体の厚さに含まれる誤差が大きくなる。 Since the device disclosed in Patent Document 1 does not need to continuously perform AD conversion, the configuration of the device is simple and the power consumption is reduced. On the other hand, in the apparatus, when the amplitude of the echo signal changes due to the corrosion of the subject or the like, the timing at which the voltage of the echo signal reaches the threshold value of the comparator changes. As a result, the error included in the measured thickness of the subject becomes large.
　本発明は、超音波信号を使用する時間計測を高精度に実行することができる超音波計測装置を提供することを目的とする。 An object of the present invention is to provide an ultrasonic measuring device capable of performing time measurement using an ultrasonic signal with high accuracy.
　本発明の第１の態様によれば、超音波計測装置は、超音波振動子、第１の比較器、第２の比較器、時間計測回路、および時間算出回路を有する。前記超音波振動子は、超音波信号を被検体に送信し、かつ前記超音波信号の反射信号を前記被検体から受信し、かつ前記反射信号に基づいてエコー信号を生成する。前記エコー信号は、基準電圧よりも正側の振幅と前記基準電圧よりも負側の振幅とを持つ。前記第１の比較器は、前記エコー信号の電圧と前記基準電圧よりも正側の第１の閾値とを比較し、前記エコー信号の前記電圧が前記第１の閾値と一致した第１のタイミングで第１の信号を出力する。前記第２の比較器は、前記エコー信号の電圧と前記基準電圧よりも負側の第２の閾値とを比較し、前記エコー信号の前記電圧が前記第２の閾値と一致した第２のタイミングで第２の信号を出力する。前記時間計測回路は、前記第１の信号に基づいて、前記超音波振動子が前記超音波信号を送信するタイミングと関連付けられたスタートタイミングから前記第１のタイミングまでの第１の時間を計測し、かつ前記第２の信号に基づいて前記スタートタイミングから前記第２のタイミングまでの第２の時間を計測する。前記時間算出回路は、前記第１の時間および前記第２の時間に基づいて前記スタートタイミングからゼロクロス点までの時間であるゼロクロス時間を算出する。前記ゼロクロス点は、前記エコー信号の電圧が前記第１のタイミングおよび前記第２のタイミングの間に前記基準電圧と一致したタイミングを示す。 According to the first aspect of the present invention, the ultrasonic measuring device includes an ultrasonic vibrator, a first comparator, a second comparator, a time measuring circuit, and a time calculating circuit. The ultrasonic vibrator transmits an ultrasonic signal to a subject, receives a reflected signal of the ultrasonic signal from the subject, and generates an echo signal based on the reflected signal. The echo signal has an amplitude on the positive side of the reference voltage and an amplitude on the negative side of the reference voltage. The first comparator compares the voltage of the echo signal with the first threshold value on the positive side of the reference voltage, and the first timing at which the voltage of the echo signal matches the first threshold value. Outputs the first signal with. The second comparator compares the voltage of the echo signal with the second threshold value on the negative side of the reference voltage, and the second timing at which the voltage of the echo signal matches the second threshold value. Outputs the second signal. Based on the first signal, the time measuring circuit measures the first time from the start timing associated with the timing at which the ultrasonic transducer transmits the ultrasonic signal to the first timing. Moreover, the second time from the start timing to the second timing is measured based on the second signal. The time calculation circuit calculates the zero cross time, which is the time from the start timing to the zero cross point, based on the first time and the second time. The zero cross point indicates a timing at which the voltage of the echo signal coincides with the reference voltage between the first timing and the second timing.
　本発明の第２の態様によれば、第１の態様において、前記時間計測回路は、前記第１の時間および前記第２の時間の少なくとも一方を２回以上計測してもよい。前記時間算出回路は、前記第１の時間および前記第２の時間を互いに関連付けることにより第１の組み合わせおよび第２の組み合わせを生成してもよい。前記第１の組み合わせおよび前記第２の組み合わせの各々は、前記第１の時間および前記第２の時間を含む。前記第１の組み合わせの前記第１の時間は前記第２の組み合わせの前記第１の時間と異なり、または前記第１の組み合わせの前記第２の時間は前記第２の組み合わせの前記第２の時間と異なる。前記時間算出回路は、前記第１の組み合わせの前記第１の時間と前記第１の組み合わせの前記第２の時間との差である第１の差を算出してもよい。前記時間算出回路は、前記第２の組み合わせの前記第１の時間と前記第２の組み合わせの前記第２の時間との差である第２の差を算出してもよい。前記第１の差の絶対値が前記第２の差の絶対値よりも小さい場合、前記時間算出回路は、前記第１の組み合わせを使用することにより前記ゼロクロス時間を算出してもよい。前記第２の差の絶対値が前記第１の差の絶対値よりも小さい場合、前記時間算出回路は、前記第２の組み合わせを使用することにより前記ゼロクロス時間を算出してもよい。 According to the second aspect of the present invention, in the first aspect, the time measuring circuit may measure at least one of the first time and the second time two or more times. The time calculation circuit may generate a first combination and a second combination by associating the first time and the second time with each other. Each of the first combination and the second combination includes the first time and the second time. The first time of the first combination is different from the first time of the second combination, or the second time of the first combination is the second time of the second combination. Different from. The time calculation circuit may calculate the first difference, which is the difference between the first time of the first combination and the second time of the first combination. The time calculation circuit may calculate a second difference, which is the difference between the first time of the second combination and the second time of the second combination. When the absolute value of the first difference is smaller than the absolute value of the second difference, the time calculation circuit may calculate the zero cross time by using the first combination. When the absolute value of the second difference is smaller than the absolute value of the first difference, the time calculation circuit may calculate the zero cross time by using the second combination.
　本発明の第３の態様によれば、第１の態様において、前記第１の時間と前記第２の時間との差の絶対値が所定値以内である場合、前記時間算出回路は前記ゼロクロス時間を算出してもよい。 According to the third aspect of the present invention, in the first aspect, when the absolute value of the difference between the first time and the second time is within a predetermined value, the time calculation circuit has the zero cross time. May be calculated.
　本発明の第４の態様によれば、第１の態様において、前記時間計測回路は、前記第１の時間を示す第１のデジタル値と、前記第２の時間を示す第２のデジタル値とを生成するＴＤＣ（Ｔｉｍｅ－Ｔｏ－Ｄｉｇｉｔａｌ）回路であってもよい。前記時間算出回路は、前記第１のデジタル値および前記第２のデジタル値に基づいて前記ゼロクロス時間を算出してもよい。 According to a fourth aspect of the present invention, in the first aspect, the time measuring circuit includes a first digital value indicating the first time and a second digital value indicating the second time. It may be a TDC (Time-To-Digital) circuit that generates. The time calculation circuit may calculate the zero cross time based on the first digital value and the second digital value.
　本発明の第５の態様によれば、第４の態様において、前記時間計測回路は、前記第１の時間および前記第２の時間の少なくとも一方を２回以上計測してもよい。前記時間計測回路は、前記第１のデジタル値および前記第２のデジタル値の少なくとも一方を２個以上生成してもよい。前記時間算出回路は、前記第１の時間および前記第２の時間の２つ以上の組み合わせから選択された前記第１の時間および前記第２の時間の組み合わせに対応する前記第１のデジタル値および前記第２のデジタル値を使用することにより前記ゼロクロス時間を算出してもよい。 According to the fifth aspect of the present invention, in the fourth aspect, the time measuring circuit may measure at least one of the first time and the second time two or more times. The time measurement circuit may generate at least two or more of the first digital value and the second digital value. The time calculation circuit comprises the first digital value and the corresponding combination of the first time and the second time selected from two or more combinations of the first time and the second time. The zero cross time may be calculated by using the second digital value.
　本発明の第６の態様によれば、第１の態様において、前記超音波計測装置は、第１の数および第２の数の少なくとも一方に基づいて前記第１の閾値を変更し、かつ前記第１の数および前記第２の数の少なくとも一方に基づいて前記第２の閾値を変更する変更回路をさらに有してもよい。前記第１の数は、前記時間計測回路が前記第１の時間を計測した回数を示す。前記第２の数は、前記時間計測回路が前記第２の時間を計測した回数を示す。 According to a sixth aspect of the present invention, in the first aspect, the ultrasonic measuring device changes the first threshold value based on at least one of a first number and a second number, and said. Further, there may be a change circuit that changes the second threshold value based on at least one of the first number and the second number. The first number indicates the number of times that the time measuring circuit measures the first time. The second number indicates the number of times that the time measuring circuit measures the second time.
　本発明の第７の態様によれば、第６の態様において、前記超音波計測装置は、前記エコー信号を所定のゲインで増幅する増幅器をさらに有してもよい。前記変更回路は、前記第１の数および前記第２の数の少なくとも一方に基づいて前記ゲインを変更してもよい。 According to the seventh aspect of the present invention, in the sixth aspect, the ultrasonic measuring device may further include an amplifier that amplifies the echo signal with a predetermined gain. The change circuit may change the gain based on at least one of the first number and the second number.
　本発明の第８の態様によれば、第４の態様において、前記超音波計測装置は、第１のエッジおよび第２のエッジを持つ第３の信号を生成する信号生成回路をさらに有してもよい。前記第１のエッジは、前記第１のタイミングと同期する。前記第２のエッジは、前記第２のタイミングと同期する。前記第１のエッジおよび前記第２のエッジの一方は立ち上がりエッジである。前記第１のエッジおよび前記第２のエッジの他方は立ち下がりエッジである。前記時間計測回路は、前記第１のエッジが前記第３の信号に現れたタイミングで前記第１のデジタル値を生成し、かつ前記第２のエッジが前記第３の信号に現れたタイミングで前記第２のデジタル値を生成してもよい。 According to an eighth aspect of the present invention, in the fourth aspect, the ultrasonic measuring device further includes a signal generation circuit that generates a third signal having a first edge and a second edge. May be good. The first edge is synchronized with the first timing. The second edge is synchronized with the second timing. One of the first edge and the second edge is a rising edge. The other of the first edge and the second edge is a falling edge. The time measurement circuit generates the first digital value at the timing when the first edge appears in the third signal, and the time measurement circuit generates the first digital value at the timing when the second edge appears in the third signal. A second digital value may be generated.
　本発明の第９の態様によれば、第１の態様において、前記超音波計測装置は、前記第１の時間および前記第２の時間の少なくとも一方に基づいて前記エコー信号の最大振幅を推定する振幅推定回路をさらに有してもよい。 According to a ninth aspect of the present invention, in the first aspect, the ultrasonic measuring device estimates the maximum amplitude of the echo signal based on at least one of the first time and the second time. It may further have an amplitude estimation circuit.
　本発明の第１０の態様によれば、第９の態様において、前記振幅推定回路は、前記第１の時間および前記第２の時間の一方と前記ゼロクロス時間との差に基づいて、かつ前記超音波振動子の共振周波数に基づいて前記最大振幅を推定してもよい。 According to the tenth aspect of the present invention, in the ninth aspect, the amplitude estimation circuit is based on the difference between one of the first time and the second time and the zero cross time, and is super. The maximum amplitude may be estimated based on the resonance frequency of the sound wave transducer.
　本発明の第１１の態様によれば、第９の態様において、前記超音波計測装置は、前記第１の時間、前記第２の時間、前記第１の閾値、および前記第２の閾値を入力データとして使用し、かつ前記エコー信号の振幅を正解データとして得る機械学習を通して得られた学習モデルを記憶するメモリをさらに有してもよい。前記振幅推定回路は、前記学習モデルを使用することにより、前記第１の時間、前記第２の時間、前記第１の閾値、および前記第２の閾値に基づいて前記最大振幅を推定してもよい。 According to the eleventh aspect of the present invention, in the ninth aspect, the ultrasonic measuring device inputs the first time, the second time, the first threshold value, and the second threshold value. It may further have a memory for storing a learning model obtained through machine learning which is used as data and obtains the amplitude of the echo signal as correct answer data. The amplitude estimation circuit may estimate the maximum amplitude based on the first time, the second time, the first threshold, and the second threshold by using the learning model. good.
　本発明の第１２の態様によれば、第９の態様において、前記超音波振動子が前記超音波信号を第１のタイミングで前記被検体に送信したとき、前記振幅推定回路は前記最大振幅である第１の振幅を推定してもよい。前記超音波振動子が前記超音波信号を前記第１のタイミングよりも後の第２のタイミングで前記被検体に送信したとき、前記振幅推定回路は前記最大振幅である第２の振幅を推定してもよい。前記超音波計測装置は、前記第１の振幅および前記第２の振幅に基づいて前記被検体の腐食の程度を推定する腐食推定回路をさらに有してもよい。 According to the twelfth aspect of the present invention, in the ninth aspect, when the ultrasonic oscillator transmits the ultrasonic signal to the subject at the first timing, the amplitude estimation circuit has the maximum amplitude. A first amplitude may be estimated. When the ultrasonic vibrator transmits the ultrasonic signal to the subject at a second timing after the first timing, the amplitude estimation circuit estimates the second amplitude, which is the maximum amplitude. You may. The ultrasonic measuring device may further include a corrosion estimation circuit that estimates the degree of corrosion of the subject based on the first amplitude and the second amplitude.
　本発明の第１３の態様によれば、第９の態様において、前記振幅推定回路は、前記第１の時間および前記第２の時間の少なくとも一方を使用することにより前記エコー信号の振幅を示す曲線の傾きを前記ゼロクロス点において推定し、かつ前記傾きに基づいて前記最大振幅を推定してもよい。 According to the thirteenth aspect of the present invention, in the ninth aspect, the amplitude estimation circuit is a curve showing the amplitude of the echo signal by using at least one of the first time and the second time. The slope of is estimated at the zero cross point, and the maximum amplitude may be estimated based on the slope.
　上記の各態様によれば、超音波計測装置は、超音波信号を使用する時間計測を高精度に実行することができる。 According to each of the above aspects, the ultrasonic measuring device can perform time measurement using an ultrasonic signal with high accuracy.
本発明の第１の実施形態の超音波計測装置の構成を示すブロック図である。It is a block diagram which shows the structure of the ultrasonic wave measuring apparatus of 1st Embodiment of this invention. 本発明の第１の実施形態の超音波計測装置における各信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of each signal in the ultrasonic measuring apparatus of 1st Embodiment of this invention. 本発明の第１の実施形態の超音波計測装置における各信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of each signal in the ultrasonic measuring apparatus of 1st Embodiment of this invention. 本発明の第１の実施形態の超音波計測装置における各信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of each signal in the ultrasonic measuring apparatus of 1st Embodiment of this invention. 本発明の第１の実施形態の超音波計測装置における各信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of each signal in the ultrasonic measuring apparatus of 1st Embodiment of this invention. 本発明の第１の実施形態の超音波計測装置における各信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of each signal in the ultrasonic measuring apparatus of 1st Embodiment of this invention. 本発明の第２の実施形態の超音波計測装置の構成を示すブロック図である。It is a block diagram which shows the structure of the ultrasonic wave measuring apparatus of 2nd Embodiment of this invention. 本発明の第２の実施形態の超音波計測装置における各信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of each signal in the ultrasonic measuring apparatus of 2nd Embodiment of this invention. 本発明の第３の実施形態において超音波信号が伝搬する時間を示す図である。It is a figure which shows the time when the ultrasonic signal propagates in the 3rd Embodiment of this invention. 本発明の第３の実施形態の超音波計測装置の構成を示すブロック図である。It is a block diagram which shows the structure of the ultrasonic wave measuring apparatus of 3rd Embodiment of this invention. 本発明の第３の実施形態の超音波計測装置における各信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of each signal in the ultrasonic measuring apparatus of 3rd Embodiment of this invention. 本発明の第４の実施形態において実施される検査の状況の例を示す図である。It is a figure which shows the example of the situation of the inspection carried out in 4th Embodiment of this invention. 本発明の第４の実施形態において実施される検査における各信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of each signal in the inspection carried out in 4th Embodiment of this invention. 本発明の第４の実施形態の超音波計測装置の構成を示すブロック図である。It is a block diagram which shows the structure of the ultrasonic wave measuring apparatus of 4th Embodiment of this invention. 本発明の第４の実施形態におけるエコー信号の波形を示すグラフである。It is a graph which shows the waveform of the echo signal in 4th Embodiment of this invention. 本発明の第４の実施形態の第１の変形例におけるエコー信号の波形を示すグラフである。It is a graph which shows the waveform of the echo signal in the 1st modification of the 4th Embodiment of this invention. 本発明の第４の実施形態の第２の変形例の超音波計測装置の構成を示すブロック図である。It is a block diagram which shows the structure of the ultrasonic measuring apparatus of the 2nd modification of the 4th Embodiment of this invention. 本発明の第４の実施形態の第２の変形例におけるエコー信号の波形を示すタイミングチャートである。It is a timing chart which shows the waveform of the echo signal in the 2nd modification of the 4th Embodiment of this invention. 本発明の第４の実施形態の第２の変形例における第１の時間、第２の時間、第１の閾値、および第２の閾値の関係を示すグラフである。It is a graph which shows the relationship of the 1st time, the 2nd time, the 1st threshold value, and the 2nd threshold value in the 2nd modification of the 4th Embodiment of this invention. 本発明の第４の実施形態の第２の変形例における４つの閾値の関係を示すグラフである。It is a graph which shows the relationship of four thresholds in the 2nd modification of the 4th Embodiment of this invention. 従来技術の超音波計測装置の構成を示すブロック図である。It is a block diagram which shows the structure of the ultrasonic measuring apparatus of a prior art. 従来技術において超音波信号が伝搬する時間を示す図である。It is a figure which shows the time when the ultrasonic signal propagates in the prior art. ＴＤＣ回路の構成を示すブロック図である。It is a block diagram which shows the structure of a TDC circuit.
　図面を参照し、本発明の実施形態を説明する。 An embodiment of the present invention will be described with reference to the drawings.
　（第１の実施形態）
　図１は、本発明の第１の実施形態の超音波計測装置１の構成を示す。図１に示す超音波計測装置１は、超音波振動子１０、駆動回路２０、ＣＰＵ３０（時間算出回路）、パルス遮断回路４０、第１の増幅器５０、第２の増幅器６０、第１の比較器７０、第２の比較器８０、第１の時間計測回路９０、および第２の時間計測回路１００を有する。 (First Embodiment)
FIG. 1 shows the configuration of the ultrasonic measuring device 1 according to the first embodiment of the present invention. The ultrasonic measuring device 1 shown in FIG. 1 includes an ultrasonic vibrator 10, a drive circuit 20, a CPU 30 (time calculation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a first comparator. It has 70, a second comparator 80, a first time measuring circuit 90, and a second time measuring circuit 100.
　超音波計測装置１の概略構成について説明する。超音波振動子１０は、超音波信号を被検体に送信し、かつ超音波信号の反射信号を被検体から受信し、かつ反射信号に基づいてエコー信号を生成する。エコー信号は、基準電圧よりも正側の振幅と基準電圧よりも負側の振幅とを持つ。第１の比較器７０は、エコー信号の電圧と基準電圧よりも正側の第１の閾値とを比較する。第１の比較器７０は、エコー信号の電圧が第１の閾値と一致した第１のタイミングで第１の信号を出力する。第２の比較器８０は、エコー信号の電圧と基準電圧よりも負側の第２の閾値とを比較する。第２の比較器８０は、エコー信号の電圧が第２の閾値と一致した第２のタイミングで第２の信号を出力する。第１の時間計測回路９０は、第１の信号に基づいて、超音波振動子１０が超音波信号を送信するタイミングと関連付けられたスタートタイミングから第１のタイミングまでの第１の時間を計測する。第２の時間計測回路１００は、第２の信号に基づいてスタートタイミングから第２のタイミングまでの第２の時間を計測する。ＣＰＵ３０は、第１の時間および第２の時間に基づいてスタートタイミングからゼロクロス点までの時間であるゼロクロス時間を算出する。ゼロクロス点は、エコー信号の電圧が第１のタイミングおよび第２のタイミングの間に基準電圧と一致したタイミングを示す。 The schematic configuration of the ultrasonic measuring device 1 will be described. The ultrasonic vibrator 10 transmits an ultrasonic signal to a subject, receives a reflected signal of the ultrasonic signal from the subject, and generates an echo signal based on the reflected signal. The echo signal has an amplitude on the positive side of the reference voltage and an amplitude on the negative side of the reference voltage. The first comparator 70 compares the voltage of the echo signal with the first threshold value on the positive side of the reference voltage. The first comparator 70 outputs the first signal at the first timing when the voltage of the echo signal matches the first threshold value. The second comparator 80 compares the voltage of the echo signal with the second threshold value on the negative side of the reference voltage. The second comparator 80 outputs the second signal at the second timing when the voltage of the echo signal matches the second threshold value. The first time measuring circuit 90 measures the first time from the start timing associated with the timing at which the ultrasonic vibrator 10 transmits the ultrasonic signal to the first timing based on the first signal. The second time measurement circuit 100 measures the second time from the start timing to the second timing based on the second signal. The CPU 30 calculates the zero cross time, which is the time from the start timing to the zero cross point, based on the first time and the second time. The zero cross point indicates the timing at which the voltage of the echo signal coincides with the reference voltage between the first timing and the second timing.
　超音波計測装置１の詳細な構成について説明する。ＣＰＵ３０は、パルスＴＸｐｒｅを生成し、かつパルスＴＸｐｒｅを駆動回路２０に出力する。ＣＰＵ３０は、第１の時間計測回路９０が計測する第１の時間および第２の時間計測回路１００が計測する第２の時間の各々のスタートタイミングを示すスタートパルスＳＴＡＲＴを第１の時間計測回路９０および第２の時間計測回路１００に出力する。ＣＰＵ３０は、第１の時間計測回路９０から出力された第１のデジタル値ＴＤＣ１と、第２の時間計測回路１００から出力された第２のデジタル値ＴＤＣ２とを受信する。ＣＰＵ３０は、第１のデジタル値ＴＤＣ１および第２のデジタル値ＴＤＣ２に基づいてゼロクロス時間を算出する。ゼロクロス時間を算出する具体的な方法については、後述する。ＣＰＵ３０は、ゼロクロス時間に基づいて被検体の厚さを算出する。 The detailed configuration of the ultrasonic measuring device 1 will be described. The CPU 30 generates a pulse TXpre and outputs the pulse TXpre to the drive circuit 20. The CPU 30 sets a start pulse START indicating the start timing of each of the first time measured by the first time measuring circuit 90 and the second time measured by the second time measuring circuit 100 to the first time measuring circuit 90 and the first time measuring circuit 90. It is output to the second time measurement circuit 100. The CPU 30 receives the first digital value TDC1 output from the first time measurement circuit 90 and the second digital value TDC2 output from the second time measurement circuit 100. The CPU 30 calculates the zero cross time based on the first digital value TDC1 and the second digital value TDC2. The specific method for calculating the zero cross time will be described later. The CPU 30 calculates the thickness of the subject based on the zero cross time.
　ＣＰＵ３０の代わりにＤＳＰ（Ｄｉｇｉｔａｌ　Ｓｉｇｎａｌ　Ｐｒｏｃｅｓｓｏｒ）のようなプロセッサが使用されてもよい。ＣＰＵ３０は、ＡＳＩＣ（Ａｐｐｌｉｃａｔｉｏｎ　Ｓｐｅｃｉｆｉｃ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）またはＦＰＧＡ（Ｆｉｅｌｄ－Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｔｅ　Ａｒｒａｙ）のような回路で構成されてもよい。 A processor such as a DSP (Digital Signal Processor) may be used instead of the CPU 30. The CPU 30 may be configured by a circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).
　ＣＰＵ３０は、プログラムを読み込み、かつ読み込まれたプログラムを実行してもよい。そのプログラムは、ＣＰＵ３０の動作を規定する命令を含む。つまり、ＣＰＵ３０の機能はソフトウェアにより実現されてもよい。そのプログラムは、例えばフラッシュメモリのような「コンピュータ読み取り可能な記録媒体」により提供されてもよい。そのプログラムは、そのプログラムを保持するコンピュータから、伝送媒体を経由して、あるいは伝送媒体中の伝送波により超音波計測装置１に伝送されてもよい。プログラムを伝送する「伝送媒体」は、情報を伝送する機能を有する媒体である。情報を伝送する機能を有する媒体は、インターネット等のネットワーク（通信網）および電話回線等の通信回線（通信線）を含む。上述したプログラムは、前述した機能の一部を実現してもよい。さらに、上述したプログラムは、差分ファイル（差分プログラム）であってもよい。コンピュータに既に記録されているプログラムと差分プログラムとの組合せが、前述した機能を実現してもよい。 The CPU 30 may read the program and execute the read program. The program includes instructions that define the operation of the CPU 30. That is, the function of the CPU 30 may be realized by software. The program may be provided by a "computer-readable recording medium" such as flash memory. The program may be transmitted from the computer holding the program to the ultrasonic measuring device 1 via the transmission medium or by the transmission wave in the transmission medium. A "transmission medium" for transmitting a program is a medium having a function of transmitting information. The medium having a function of transmitting information includes a network (communication network) such as the Internet and a communication line (communication line) such as a telephone line. The above-mentioned program may realize a part of the above-mentioned function. Further, the above-mentioned program may be a difference file (difference program). The combination of the program already recorded in the computer and the difference program may realize the above-mentioned function.
　駆動回路２０は、パルスＴＸｐｒｅを受信したタイミングで駆動信号ＴＸを生成し、かつ駆動信号ＴＸを超音波振動子１０に出力する。超音波振動子１０は、圧電素子である。超音波振動子１０は、駆動信号ＴＸに基づいて超音波信号を生成し、かつ超音波信号を測定対象である被検体に照射する。 The drive circuit 20 generates a drive signal TX at the timing of receiving the pulse TXpre, and outputs the drive signal TX to the ultrasonic vibrator 10. The ultrasonic vibrator 10 is a piezoelectric element. The ultrasonic vibrator 10 generates an ultrasonic signal based on the drive signal TX, and irradiates the subject to be measured with the ultrasonic signal.
　被検体に照射された超音波信号は、被検体の境界面で反射する。被検体の境界面で反射した超音波信号（反射信号）は超音波振動子１０に入射する。超音波振動子１０は、反射信号を受信し、かつ反射信号に基づいてエコー信号ＲＸを生成する。超音波振動子１０は、生成されたエコー信号ＲＸをパルス遮断回路４０に出力する。例えば、パルス遮断回路４０は、スイッチおよび容量を含む。パルス遮断回路４０は、不要な信号成分を遮断することによりエコー信号ＲＸからその信号成分を除去する。パルス遮断回路４０は、不要な信号成分が除去されたエコー信号ＲＸａｃを第１の増幅器５０に出力する。 The ultrasonic signal applied to the subject is reflected at the interface of the subject. The ultrasonic signal (reflected signal) reflected at the interface of the subject is incident on the ultrasonic vibrator 10. The ultrasonic vibrator 10 receives the reflected signal and generates an echo signal RX based on the reflected signal. The ultrasonic vibrator 10 outputs the generated echo signal RX to the pulse cutoff circuit 40. For example, the pulse cutoff circuit 40 includes a switch and a capacitance. The pulse cutoff circuit 40 removes the signal component from the echo signal RX by cutting off an unnecessary signal component. The pulse cutoff circuit 40 outputs the echo signal RXac from which unnecessary signal components have been removed to the first amplifier 50.
　第１の増幅器５０は、ＬＮＡである。第１の増幅器５０は、エコー信号ＲＸａｃを固定されたゲインで増幅することによりエコー信号ＲＸａｃ１を生成する。第１の増幅器５０は、エコー信号ＲＸａｃに与えるノイズが最小限になるようにエコー信号ＲＸａｃ１を生成する。第１の増幅器５０は、生成されたエコー信号ＲＸａｃ１を第２の増幅器６０に出力する。第２の増幅器６０は、ＰＧＡである。第２の増幅器６０は、エコー信号ＲＸａｃ１を予め設定されたゲインで増幅することによりエコー信号ＲＸａｃ２を生成する。第２の増幅器６０は、生成されたエコー信号ＲＸａｃ２を第１の比較器７０および第２の比較器８０に出力する。 The first amplifier 50 is an LNA. The first amplifier 50 generates the echo signal RXac1 by amplifying the echo signal RXac with a fixed gain. The first amplifier 50 generates the echo signal RXac1 so as to minimize the noise given to the echo signal RXac. The first amplifier 50 outputs the generated echo signal RXac1 to the second amplifier 60. The second amplifier 60 is a PGA. The second amplifier 60 generates the echo signal RXac2 by amplifying the echo signal RXac1 with a preset gain. The second amplifier 60 outputs the generated echo signal RXac2 to the first comparator 70 and the second comparator 80.
　第１の比較器７０は、エコー信号ＲＸａｃ２を受信し、かつエコー信号ＲＸａｃ２の電圧と基準電圧よりも正側の第１の閾値ＴＨｐとを比較する。エコー信号ＲＸａｃ２の電圧が増加し、かつ第１の閾値ＴＨｐと一致したとき、第１の比較器７０は、第１のタイミングを示す第１の計測制御信号ＳＴＯＰ１（第１の信号）を第１の時間計測回路９０に出力する。第２の比較器８０は、エコー信号ＲＸａｃ２を受信し、かつエコー信号ＲＸａｃ２の電圧と基準電圧よりも負側の第２の閾値ＴＨｎとを比較する。第２の閾値ＴＨｎは、第１の閾値ＴＨｐよりも小さい。エコー信号ＲＸａｃ２の電圧が増加し、かつ第２の閾値ＴＨｎと一致したとき、第２の比較器８０は、第２のタイミングを示す第２の計測制御信号ＳＴＯＰ２（第２の信号）を第２の時間計測回路１００に出力する。 The first comparator 70 receives the echo signal RXac2 and compares the voltage of the echo signal RXac2 with the first threshold value THp on the positive side of the reference voltage. When the voltage of the echo signal RXac2 increases and matches the first threshold value THp, the first comparator 70 sets the first measurement control signal STOP1 (first signal) indicating the first timing. Is output to the time measurement circuit 90 of. The second comparator 80 receives the echo signal RXac2 and compares the voltage of the echo signal RXac2 with the second threshold value THn on the negative side of the reference voltage. The second threshold THn is smaller than the first threshold THp. When the voltage of the echo signal RXac2 increases and coincides with the second threshold value THn, the second comparator 80 sets the second measurement control signal STOP2 (second signal) indicating the second timing to the second. Is output to the time measurement circuit 100 of.
　第１の時間計測回路９０および第２の時間計測回路１００は、ＴＤＣ（Ｔｉｍｅ－Ｔｏ－Ｄｉｇｉｔａｌ）回路である。第１の時間計測回路９０は、スタートパルスＳＴＡＲＴが示すスタートタイミングから第１の計測制御信号ＳＴＯＰ１が示す第１のタイミングまでの第１の時間を計測する。第１の時間計測回路９０は、第１の時間を示す第１のデジタル値ＴＤＣ１を生成し、かつ保持する。第１の時間計測回路９０は、生成された第１のデジタル値ＴＤＣ１をＣＰＵ３０に出力する。 The first time measurement circuit 90 and the second time measurement circuit 100 are TDC (Time-To-Digital) circuits. The first time measurement circuit 90 measures the first time from the start timing indicated by the start pulse START to the first timing indicated by the first measurement control signal STOP1. The first time measurement circuit 90 generates and holds a first digital value TDC1 indicating a first time. The first time measurement circuit 90 outputs the generated first digital value TDC1 to the CPU 30.
　図２３は、第１の時間計測回路９０に含まれるＴＤＣ回路の構成の例を示す。図２３に示すＴＤＣ回路は、クロックカウンタ３００、位相クロック生成部３１０、位相検出部３２０、およびデコーダ３３０を有する。クロックカウンタ３００は、スタートパルスＳＴＡＲＴが示すスタートタイミングから計測制御信号ＳＴＯＰが示すタイミングまでのクロックＣＬＫのパルスの数（クロック数）をカウントする。位相クロック生成部３１０は、クロックＣＬＫに基づいてクロックＣＬＫ－９０、クロックＣＬＫ－１８０、およびクロックＣＬＫ－２７０を生成する。クロックＣＬＫ－９０は、クロックＣＬＫの位相よりも９０度遅れた位相を持つ。クロックＣＬＫ－１８０は、クロックＣＬＫの位相よりも１８０度遅れた位相を持つ。クロックＣＬＫ－２７０は、クロックＣＬＫの位相よりも２７０度遅れた位相を持つ。位相クロック生成部３１０は、クロックＣＬＫ、クロックＣＬＫ－９０、クロックＣＬＫ－１８０、およびクロックＣＬＫ－２７０を位相検出部３２０に出力する。位相検出部３２０は、計測制御信号ＳＴＯＰが示すタイミングにおける４つのクロックの位相の状態を検出する。デコーダ３３０は、クロック数および４つのクロックの位相の状態を示すデジタル値ＴＤＣ０を出力する。この構成により、ＴＤＣ回路は、クロックの周波数を高くすることなく、低い消費電力で時間計測を高精度に実行することができる。 FIG. 23 shows an example of the configuration of the TDC circuit included in the first time measurement circuit 90. The TDC circuit shown in FIG. 23 includes a clock counter 300, a phase clock generation unit 310, a phase detection unit 320, and a decoder 330. The clock counter 300 counts the number of clock CLK pulses (clock number) from the start timing indicated by the start pulse START to the timing indicated by the measurement control signal STOP. The phase clock generation unit 310 generates the clock CLK-90, the clock CLK-180, and the clock CLK-270 based on the clock CLK. The clock CLK-90 has a phase 90 degrees behind the phase of the clock CLK. The clock CLK-180 has a phase 180 degrees behind the phase of the clock CLK. The clock CLK-270 has a phase 270 degrees behind the phase of the clock CLK. The phase clock generation unit 310 outputs the clock CLK, the clock CLK-90, the clock CLK-180, and the clock CLK-270 to the phase detection unit 320. The phase detection unit 320 detects the phase states of the four clocks at the timing indicated by the measurement control signal STOP. The decoder 330 outputs a digital value TDC0 indicating the number of clocks and the phase states of the four clocks. With this configuration, the TDC circuit can perform time measurement with high accuracy with low power consumption without increasing the frequency of the clock.
　第２の時間計測回路１００は、スタートパルスＳＴＡＲＴが示すスタートタイミングから第２の計測制御信号ＳＴＯＰ２が示す第２のタイミングまでの第２の時間を計測する。第２の時間計測回路１００は、第２の時間を示す第２のデジタル値ＴＤＣ２を生成し、かつ保持する。第２の時間計測回路１００は、生成された第２のデジタル値ＴＤＣ２をＣＰＵ３０に出力する。第２の時間計測回路１００も第１の時間計測回路９０と同様にＴＤＣ回路で構成される。 The second time measurement circuit 100 measures the second time from the start timing indicated by the start pulse START to the second timing indicated by the second measurement control signal STOP2. The second time measurement circuit 100 generates and holds a second digital value TDC2 indicating a second time. The second time measurement circuit 100 outputs the generated second digital value TDC2 to the CPU 30. The second time measurement circuit 100 is also composed of a TDC circuit like the first time measurement circuit 90.
　パルス遮断回路４０は必須ではない。したがって、エコー信号ＲＸが超音波振動子１０から第１の増幅器５０に出力されてもよい。第１の増幅器５０および第２の増幅器６０は必須ではない。したがって、エコー信号ＲＸａｃがパルス遮断回路４０から第１の比較器７０および第２の比較器８０に出力されてもよい。あるいは、エコー信号ＲＸが超音波振動子１０から第１の比較器７０および第２の比較器８０に出力されてもよい。 The pulse cutoff circuit 40 is not essential. Therefore, the echo signal RX may be output from the ultrasonic vibrator 10 to the first amplifier 50. The first amplifier 50 and the second amplifier 60 are not essential. Therefore, the echo signal RXac may be output from the pulse cutoff circuit 40 to the first comparator 70 and the second comparator 80. Alternatively, the echo signal RX may be output from the ultrasonic transducer 10 to the first comparator 70 and the second comparator 80.
　図２を参照し、超音波計測装置１の動作を説明する。図２は、超音波計測装置１における各信号の波形を示す。パルスＴＸｐｒｅ、駆動信号ＴＸ、スタートパルスＳＴＡＲＴ、エコー信号ＲＸ、エコー信号ＲＸａｃ２、第１の計測制御信号ＳＴＯＰ１、および第２の計測制御信号ＳＴＯＰ２の各々の波形が図２に示されている。図２における横方向は時間を示し、かつ図２における縦方向は各信号の電圧を示す。 The operation of the ultrasonic measuring device 1 will be described with reference to FIG. FIG. 2 shows the waveform of each signal in the ultrasonic measuring device 1. The waveforms of the pulse TXpre, the drive signal TX, the start pulse START, the echo signal RX, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG. The horizontal direction in FIG. 2 indicates time, and the vertical direction in FIG. 2 indicates the voltage of each signal.
　ＣＰＵ３０は、タイミングｔｇ１でパルスＴＸｐｒｅを駆動回路２０に出力する。駆動回路２０は、パルスＴＸｐｒｅに基づいて駆動信号ＴＸを生成し、かつ駆動信号ＴＸを超音波振動子１０に出力する。超音波振動子１０は、駆動信号ＴＸに基づいて超音波信号を生成し、かつ超音波信号を被検体に照射する。図２に示す例では説明を簡単にするために、ＣＰＵ３０がパルスＴＸｐｒｅを駆動回路２０に出力したタイミングと、超音波振動子１０が超音波信号を出力するタイミングとの差は無視される。 The CPU 30 outputs the pulse TXpre to the drive circuit 20 at the timing tg1. The drive circuit 20 generates a drive signal TX based on the pulse TXpre, and outputs the drive signal TX to the ultrasonic vibrator 10. The ultrasonic vibrator 10 generates an ultrasonic signal based on the drive signal TX and irradiates the subject with the ultrasonic signal. In the example shown in FIG. 2, for the sake of simplicity, the difference between the timing at which the CPU 30 outputs the pulse TXpre to the drive circuit 20 and the timing at which the ultrasonic transducer 10 outputs the ultrasonic signal is ignored.
　超音波信号は被検体の境界面で反射し、反射信号が超音波振動子１０に入射する。超音波振動子１０は、反射信号を受信し、かつ反射信号に基づいてエコー信号ＲＸを生成する。エコー信号ＲＸは、成分ＲＸ１および成分ＲＸ２を含む。成分ＲＸ１は、被検体の表面で反射した超音波信号に基づいて生成される。成分ＲＸ２は、被検体の裏面で反射した超音波信号に基づいて生成される。 The ultrasonic signal is reflected at the interface of the subject, and the reflected signal is incident on the ultrasonic vibrator 10. The ultrasonic vibrator 10 receives the reflected signal and generates an echo signal RX based on the reflected signal. The echo signal RX includes component RX1 and component RX2. The component RX1 is generated based on the ultrasonic signal reflected on the surface of the subject. The component RX2 is generated based on the ultrasonic signal reflected on the back surface of the subject.
　超音波振動子１０は、エコー信号ＲＸをパルス遮断回路４０に出力する。パルス遮断回路４０は、エコー信号ＲＸから成分ＲＸ１を除去する。パルス遮断回路４０は、成分ＲＸ２を除去しない。成分ＲＸ２は、パルス遮断回路４０を通過する。パルス遮断回路４０は、成分ＲＸ２を含むエコー信号ＲＸａｃを第１の増幅器５０に出力する。 The ultrasonic vibrator 10 outputs the echo signal RX to the pulse cutoff circuit 40. The pulse cutoff circuit 40 removes the component RX1 from the echo signal RX. The pulse cutoff circuit 40 does not remove the component RX2. The component RX2 passes through the pulse cutoff circuit 40. The pulse cutoff circuit 40 outputs an echo signal RXac including the component RX2 to the first amplifier 50.
　タイミングｔｇ１から所定の時間Ｔｓｔｏｆｆが経過したタイミングｔｇ２において、ＣＰＵ３０はスタートパルスＳＴＡＲＴを第１の時間計測回路９０および第２の時間計測回路１００に出力する。時間Ｔｓｔｏｆｆが０に設定されてもよい。成分ＲＸ１が除去されずにエコー信号ＲＸａｃに混入した場合、第１の比較器７０が成分ＲＸ１に基づいて第１の計測制御信号ＳＴＯＰ１を生成し、または第２の比較器８０が成分ＲＸ１に基づいて第２の計測制御信号ＳＴＯＰ２を生成する可能性がある。第１の時間計測回路９０および第２の時間計測回路１００は、成分ＲＸ１に基づいて生成された第１の計測制御信号ＳＴＯＰ１および第２の計測制御信号ＳＴＯＰ２をそれぞれ検出するべきではない。第１の時間計測回路９０および第２の時間計測回路１００が成分ＲＸ１に基づいて生成された第１の計測制御信号ＳＴＯＰ１および第２の計測制御信号ＳＴＯＰ２をそれぞれ誤って検出しないように時間Ｔｓｔｏｆｆが設定されることが望ましい。 At the timing tg2 when the predetermined time Tstoff has elapsed from the timing tg1, the CPU 30 outputs the start pulse START to the first time measurement circuit 90 and the second time measurement circuit 100. The time Tstoff may be set to 0. When the component RX1 is not removed and is mixed into the echo signal RXac, the first comparator 70 generates the first measurement control signal STOP1 based on the component RX1, or the second comparator 80 is based on the component RX1. There is a possibility of generating a second measurement control signal STOP2. The first time measurement circuit 90 and the second time measurement circuit 100 should not detect the first measurement control signal STOP1 and the second measurement control signal STOP2 generated based on the component RX1, respectively. The time Tstoff prevents the first time measurement circuit 90 and the second time measurement circuit 100 from erroneously detecting the first measurement control signal STOP1 and the second measurement control signal STOP2 generated based on the component RX1. It is desirable to set.
　成分ＲＸ１およびＤＣ成分をエコー信号ＲＸから除去することにより、エコー信号ＲＸａｃが生成される。第１の増幅器５０は、エコー信号ＲＸａｃを増幅することによりエコー信号ＲＸａｃ１を生成する。第２の増幅器６０は、エコー信号ＲＸａｃ１の電圧の変化に対応する信号を基準電圧Ｖｃｍに加え、かつエコー信号ＲＸａｃ１を増幅することによりエコー信号ＲＸａｃ２を生成する。エコー信号ＲＸａｃ２は、基準電圧Ｖｃｍよりも正側の振幅と基準電圧Ｖｃｍよりも負側の振幅とを持つ。第２の増幅器６０は、生成されたエコー信号ＲＸａｃ２を第１の比較器７０および第２の比較器８０に出力する。 The echo signal RXac is generated by removing the component RX1 and the DC component from the echo signal RX. The first amplifier 50 generates the echo signal RXac1 by amplifying the echo signal RXac. The second amplifier 60 generates the echo signal RXac2 by applying a signal corresponding to the change in the voltage of the echo signal RXac1 to the reference voltage Vcm and amplifying the echo signal RXac1. The echo signal RXac2 has an amplitude on the positive side of the reference voltage Vcm and an amplitude on the negative side of the reference voltage Vcm. The second amplifier 60 outputs the generated echo signal RXac2 to the first comparator 70 and the second comparator 80.
　第１の比較器７０は、エコー信号ＲＸａｃ２の電圧と第１の閾値ＴＨｐとを比較する。第１の閾値ＴＨｐは、基準電圧Ｖｃｍから所定値だけ正側に離れている。図２における上方向は、電圧の正方向を示す。つまり、図２における上方向は、電圧が増加する方向を示す。第２の比較器８０は、エコー信号ＲＸａｃ２の電圧と第２の閾値ＴＨｎとを比較する。第２の閾値ＴＨｎは、基準電圧Ｖｃｍから所定値だけ負側に離れている。図２における下方向は、電圧の負方向を示す。つまり、図２における下方向は、電圧が減少する方向を示す。例えば、基準電圧Ｖｃｍと第１の閾値ＴＨｐとの差の絶対値は、基準電圧Ｖｃｍと第２の閾値ＴＨｎとの差の絶対値と同じである。つまり、基準電圧Ｖｃｍは、第１の閾値ＴＨｐと第２の閾値ＴＨｎとの中間電圧である。基準電圧Ｖｃｍと第１の閾値ＴＨｐとの差の絶対値は、基準電圧Ｖｃｍと第２の閾値ＴＨｎとの差の絶対値と異なっていてもよい。 The first comparator 70 compares the voltage of the echo signal RXac2 with the first threshold THp. The first threshold value THp is separated from the reference voltage Vcm by a predetermined value on the positive side. The upward direction in FIG. 2 indicates the positive direction of the voltage. That is, the upward direction in FIG. 2 indicates the direction in which the voltage increases. The second comparator 80 compares the voltage of the echo signal RXac2 with the second threshold THn. The second threshold value THn is separated from the reference voltage Vcm by a predetermined value on the negative side. The downward direction in FIG. 2 indicates the negative direction of the voltage. That is, the downward direction in FIG. 2 indicates the direction in which the voltage decreases. For example, the absolute value of the difference between the reference voltage Vcm and the first threshold value THp is the same as the absolute value of the difference between the reference voltage Vcm and the second threshold value THn. That is, the reference voltage Vcm is an intermediate voltage between the first threshold value THp and the second threshold value THn. The absolute value of the difference between the reference voltage Vcm and the first threshold value THp may be different from the absolute value of the difference between the reference voltage Vcm and the second threshold value THn.
　第１の比較器７０は、ローレベルまたはハイレベルを持つ２値信号を出力する。エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐよりも小さいとき、第１の比較器７０は、ローレベルである第１の計測制御信号ＳＴＯＰ１を出力する。エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐ以上であるとき、第１の比較器７０は、ハイレベルである第１の計測制御信号ＳＴＯＰ１を出力する。 The first comparator 70 outputs a binary signal having a low level or a high level. When the voltage of the echo signal RXac2 is smaller than the first threshold value THp, the first comparator 70 outputs the first measurement control signal STOP1 which is a low level. When the voltage of the echo signal RXac2 is equal to or higher than the first threshold value THp, the first comparator 70 outputs the first measurement control signal STOP1 which is a high level.
　第２の比較器８０は、ローレベルまたはハイレベルを持つ２値信号を出力する。エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎよりも小さいとき、第２の比較器８０は、ローレベルである第２の計測制御信号ＳＴＯＰ２を出力する。エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎ以上であるとき、第２の比較器８０は、ハイレベルである第２の計測制御信号ＳＴＯＰ２を出力する。 The second comparator 80 outputs a binary signal having a low level or a high level. When the voltage of the echo signal RXac2 is smaller than the second threshold value THn, the second comparator 80 outputs the second measurement control signal STOP2 which is a low level. When the voltage of the echo signal RXac2 is equal to or higher than the second threshold value THn, the second comparator 80 outputs the second measurement control signal STOP2 which is a high level.
　スタートパルスＳＴＡＲＴがＣＰＵ３０から出力されたとき、第１の時間計測回路９０および第２の時間計測回路１００は時間の計測を開始する。第１の時間計測回路９０は、第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジまたは第１の計測制御信号ＳＴＯＰ１の立ち下がりエッジを検出し、かつその立ち上がりエッジまたは立ち下がりエッジのタイミングで第１のデジタル値ＴＤＣ１を保持する。第１の計測制御信号ＳＴＯＰ１の電圧がローレベルからハイレベルに変化するとき、第１の計測制御信号ＳＴＯＰ１は立ち上がる。第１の計測制御信号ＳＴＯＰ１の電圧がハイレベルからローレベルに変化するとき、第１の計測制御信号ＳＴＯＰ１は立ち下がる。 When the start pulse START is output from the CPU 30, the first time measurement circuit 90 and the second time measurement circuit 100 start time measurement. The first time measurement circuit 90 detects the rising edge of the first measurement control signal STOP1 or the falling edge of the first measurement control signal STOP1, and the first digital at the timing of the rising edge or the falling edge. Holds the value TDC1. When the voltage of the first measurement control signal STOP1 changes from a low level to a high level, the first measurement control signal STOP1 rises. When the voltage of the first measurement control signal STOP1 changes from a high level to a low level, the first measurement control signal STOP1 falls.
　図２に示す例では、第１の時間計測回路９０は、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジのタイミングｔｇ４までの第１の時間Ｔ１を計測する。第１の時間計測回路９０は、第１の時間Ｔ１を示す第１のデジタル値ＴＤＣ１をＣＰＵ３０に出力する。 In the example shown in FIG. 2, the first time measurement circuit 90 measures the first time T1 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg4 of the first measurement control signal STOP1. The first time measurement circuit 90 outputs the first digital value TDC1 indicating the first time T1 to the CPU 30.
　第２の時間計測回路１００は、第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジまたは第２の計測制御信号ＳＴＯＰ２の立ち下がりエッジを検出し、かつその立ち上がりエッジまたは立ち下がりエッジのタイミングで第２のデジタル値ＴＤＣ２を保持する。第２の計測制御信号ＳＴＯＰ２の電圧がローレベルからハイレベルに変化するとき、第２の計測制御信号ＳＴＯＰ２は立ち上がる。第２の計測制御信号ＳＴＯＰ２の電圧がハイレベルからローレベルに変化するとき、第２の計測制御信号ＳＴＯＰ２は立ち下がる。 The second time measurement circuit 100 detects the rising edge of the second measurement control signal STOP2 or the falling edge of the second measurement control signal STOP2, and the second digital at the timing of the rising edge or the falling edge. Holds the value TDC2. When the voltage of the second measurement control signal STOP2 changes from a low level to a high level, the second measurement control signal STOP2 rises. When the voltage of the second measurement control signal STOP2 changes from a high level to a low level, the second measurement control signal STOP2 falls.
　図２に示す例では、第２の時間計測回路１００は、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジのタイミングｔｇ３までの第２の時間Ｔ２を計測する。第２の時間計測回路１００は、第２の時間Ｔ２を示す第２のデジタル値ＴＤＣ２をＣＰＵ３０に出力する。 In the example shown in FIG. 2, the second time measurement circuit 100 measures the second time T2 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg3 of the second measurement control signal STOP2. The second time measurement circuit 100 outputs a second digital value TDC2 indicating the second time T2 to the CPU 30.
　第１の時間計測回路９０は、第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジと第１の計測制御信号ＳＴＯＰ１の立ち下がりエッジとの任意の一方を検出することができる。同様に、第２の時間計測回路１００は、第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジと第２の計測制御信号ＳＴＯＰ２の立ち下がりエッジとの任意の一方を検出することができる。 The first time measurement circuit 90 can detect any one of the rising edge of the first measurement control signal STOP1 and the falling edge of the first measurement control signal STOP1. Similarly, the second time measurement circuit 100 can detect any one of the rising edge of the second measurement control signal STOP2 and the falling edge of the second measurement control signal STOP2.
　図３を参照し、ゼロクロス時間を算出する方法を説明する。図３は、超音波計測装置１における各信号の波形を示す。スタートパルスＳＴＡＲＴ、エコー信号ＲＸａｃ２、第１の計測制御信号ＳＴＯＰ１、および第２の計測制御信号ＳＴＯＰ２の各々の波形が図３に示されている。図３における横方向は時間を示し、かつ図３における縦方向は各信号の電圧を示す。 The method of calculating the zero cross time will be described with reference to FIG. FIG. 3 shows the waveform of each signal in the ultrasonic measuring device 1. The waveforms of the start pulse START, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG. The horizontal direction in FIG. 3 indicates time, and the vertical direction in FIG. 3 indicates the voltage of each signal.
　ＣＰＵ３０は、第１のデジタル値ＴＤＣ１および第２のデジタル値ＴＤＣ２に基づいてゼロクロス時間Ｔ０を算出する。第１のデジタル値ＴＤＣ１は、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジのタイミングｔｇ４までの第１の時間Ｔ１を示す。第２のデジタル値ＴＤＣ２は、タイミングｔｇ２から第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジのタイミングｔｇ３までの第２の時間Ｔ２を示す。ゼロクロス時間Ｔ０は、タイミングｔｇ２からタイミングｔｇ０までの時間を示す。タイミングｔｇ０は、ゼロクロス点である。タイミングｔｇ０は、エコー信号ＲＸａｃ２の電圧が基準電圧Ｖｃｍに到達するタイミングを示す。タイミングｔｇ０は、タイミングｔｇ３およびタイミングｔｇ４の間にある。 The CPU 30 calculates the zero cross time T0 based on the first digital value TDC1 and the second digital value TDC2. The first digital value TDC1 indicates a first time T1 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg4 of the first measurement control signal STOP1. The second digital value TDC2 indicates the second time T2 from the timing tg2 to the timing tg3 of the rising edge of the second measurement control signal STOP2. The zero cross time T0 indicates the time from the timing tg2 to the timing tg0. Timing tg0 is the zero cross point. The timing tg0 indicates the timing at which the voltage of the echo signal RXac2 reaches the reference voltage Vcm. The timing tg0 is between the timing tg3 and the timing tg4.
　ＣＰＵ３０は、以下の式（５）に基づいて第１のデジタル値ＴＤＣ１および第２のデジタル値ＴＤＣ２の平均を算出することによりデジタル値Ｄｒｘ０を算出する。デジタル値Ｄｒｘ０は、ゼロクロス時間Ｔ０に対応する。ＣＰＵ３０は、簡易な方法でゼロクロス時間を算出することができる。
　　Ｄｒｘ０＝（ＴＤＣ１＋ＴＤＣ２）／２　　（５） The CPU 30 calculates the digital value Drx0 by calculating the average of the first digital value TDC1 and the second digital value TDC2 based on the following equation (5). The digital value Drx0 corresponds to the zero cross time T0. The CPU 30 can calculate the zero cross time by a simple method.
Drx0 = (TDC1 + TDC2) / 2 (5)
　基準電圧Ｖｃｍが第１の閾値ＴＨｐと第２の閾値ＴＨｎとの中間電圧ではない場合、ＣＰＵ３０は、基準電圧Ｖｃｍ、第１の閾値ＴＨｐ、および第２の閾値ＴＨｎの間の大きさの関係に基づいて重み付けのための係数を算出してもよい。ＣＰＵ３０は、第１のデジタル値ＴＤＣ１と、第２のデジタル値ＴＤＣ２と、その係数とを使用することによりデジタル値Ｄｒｘ０を算出してもよい。 When the reference voltage Vcm is not an intermediate voltage between the first threshold THp and the second threshold THn, the CPU 30 determines the magnitude relationship between the reference voltage Vcm, the first threshold THp, and the second threshold THn. The coefficient for weighting may be calculated based on this. The CPU 30 may calculate the digital value Drx0 by using the first digital value TDC1, the second digital value TDC2, and the coefficients thereof.
　ＣＰＵ３０は、デジタル値Ｄｒｘ０に所定のデジタル値を加算することにより、デジタル値Ｄｔｏｆを算出する。デジタル値Ｄｔｏｆは、駆動信号ＴＸが超音波振動子１０に出力されたタイミングからエコー信号ＲＸ（図２に示す成分ＲＸ２）が超音波振動子１０から出力されたタイミングまでの時間を示す。デジタル値Ｄｔｏｆは、前述した式（１）、式（３）、および式（４）における時間Ｔｔｏｆを示す。所定のデジタル値は、図２に示す時間Ｔｓｔｏｆｆを示す。 The CPU 30 calculates the digital value Dtof by adding a predetermined digital value to the digital value Drx0. The digital value Dtof indicates the time from the timing when the drive signal TX is output to the ultrasonic vibrator 10 to the timing when the echo signal RX (component RX2 shown in FIG. 2) is output from the ultrasonic vibrator 10. The digital value Dtof indicates the time Ttof in the above-mentioned equations (1), (3), and (4). The predetermined digital value indicates the time Tstoff shown in FIG.
　ＣＰＵ３０は、デジタル値Ｄｔｏｆから所定のデジタル値を減算することにより、デジタル値Ｄｔｄを算出する。デジタル値Ｄｔｄは、超音波信号が被検体に到達したタイミングから反射信号が超音波振動子１０に到達するタイミングまでの時間を示す。デジタル値Ｄｔｄは、前述した式（４）における時間（Ｔｔｏｆ－Ｔｏｆｆｓｅｔ）を示す。所定のデジタル値は、前述した式（３）および式（４）におけるオフセット時間Ｔｏｆｆｓｅｔを示す。ＣＰＵ３０は、デジタル値Ｄｔｄが示す時間と、被検体の材料に応じた音速Ｖと、式（４）とに基づいて被検体の厚さＤを算出する。 The CPU 30 calculates the digital value Dtd by subtracting a predetermined digital value from the digital value Dtof. The digital value Dtd indicates the time from the timing when the ultrasonic signal reaches the subject to the timing when the reflected signal reaches the ultrasonic vibrator 10. The digital value Dtd indicates the time (Ttof-Toffset) in the above-mentioned equation (4). The predetermined digital value indicates the offset time Toffset in the above-mentioned equations (3) and (4). The CPU 30 calculates the thickness D of the subject based on the time indicated by the digital value Dtd, the speed of sound V corresponding to the material of the subject, and the equation (4).
　第１の比較器７０は、エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐと一致する度に第１の計測制御信号ＳＴＯＰ１の電圧をハイレベルまたはローレベルに変化させる。第２の比較器８０は、エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎと一致する度に第２の計測制御信号ＳＴＯＰ２の電圧をハイレベルまたはローレベルに変化させる。 The first comparator 70 changes the voltage of the first measurement control signal STOP1 to a high level or a low level every time the voltage of the echo signal RXac2 matches the first threshold value THp. The second comparator 80 changes the voltage of the second measurement control signal STOP2 to a high level or a low level each time the voltage of the echo signal RXac2 matches the second threshold value THn.
　第１の時間計測回路９０が第１の時間を１回のみ計測し、かつ第２の時間計測回路１００が第２の時間を２回以上計測してもよい。第１の時間計測回路９０が１個のみの第１のデジタル値ＴＤＣ１を生成し、かつ第２の時間計測回路１００が２個以上の第２のデジタル値ＴＤＣ２を生成してもよい。 The first time measurement circuit 90 may measure the first time only once, and the second time measurement circuit 100 may measure the second time twice or more. The first time measuring circuit 90 may generate only one first digital value TDC1, and the second time measuring circuit 100 may generate two or more second digital values TDC2.
　あるいは、第１の時間計測回路９０が第１の時間を２回以上計測し、かつ第２の時間計測回路１００が第２の時間を１回のみ計測してもよい。第１の時間計測回路９０が２個以上の第１のデジタル値ＴＤＣ１を生成し、かつ第２の時間計測回路１００が１個のみの第２のデジタル値ＴＤＣ２を生成してもよい。 Alternatively, the first time measurement circuit 90 may measure the first time twice or more, and the second time measurement circuit 100 may measure the second time only once. The first time measurement circuit 90 may generate two or more first digital values TDC1, and the second time measurement circuit 100 may generate only one second digital value TDC2.
　あるいは、第１の時間計測回路９０が第１の時間を２回以上計測し、かつ第２の時間計測回路１００が第２の時間を２回以上計測してもよい。第１の時間計測回路９０が２個以上の第１のデジタル値ＴＤＣ１を生成し、かつ第２の時間計測回路１００が２個以上の第２のデジタル値ＴＤＣ２を生成してもよい。 Alternatively, the first time measurement circuit 90 may measure the first time twice or more, and the second time measurement circuit 100 may measure the second time twice or more. The first time measurement circuit 90 may generate two or more first digital values TDC1, and the second time measurement circuit 100 may generate two or more second digital values TDC2.
　ＴＤＣ回路が保持できるデジタル値の数は、ＴＤＣ回路の設計時に設定される。その数が多くなると、ＴＤＣ回路内のメモリが大きくなる。例えば、ＴＤＣ回路が保持できるデジタル値の数は５以上かつ１０以下である。 The number of digital values that the TDC circuit can hold is set when the TDC circuit is designed. As the number increases, the memory in the TDC circuit increases. For example, the number of digital values that the TDC circuit can hold is 5 or more and 10 or less.
　図４を参照し、第１の時間計測回路９０が第１の時間を２回以上計測し、かつ第２の時間計測回路１００が第２の時間を２回以上計測する例を説明する。図４は、図３に示す各信号の波形と同様の波形を示す。第１の比較器７０は、タイミングｔｇ４、タイミングｔｇ６、およびタイミングｔｇ８の各々においてハイレベルである第１の計測制御信号ＳＴＯＰ１を出力する。第２の比較器８０は、タイミングｔｇ３、タイミングｔｇ５、タイミングｔｇ７、およびタイミングｔｇ９の各々においてハイレベルである第２の計測制御信号ＳＴＯＰ２を出力する。 With reference to FIG. 4, an example will be described in which the first time measurement circuit 90 measures the first time twice or more, and the second time measurement circuit 100 measures the second time twice or more. FIG. 4 shows a waveform similar to the waveform of each signal shown in FIG. The first comparator 70 outputs the first measurement control signal STOP1 which is a high level at each of the timing tg4, the timing tg6, and the timing tg8. The second comparator 80 outputs a second measurement control signal STOP2 which is a high level at each of the timing tg3, the timing tg5, the timing tg7, and the timing tg9.
　第１の時間計測回路９０は、タイミングｔｇ２からタイミングｔｇ４までの第１の時間Ｔ１ａ、タイミングｔｇ２からタイミングｔｇ６までの第１の時間Ｔ１ｂ、およびタイミングｔｇ２からタイミングｔｇ８までの第１の時間Ｔ１ｃを計測する。第１の時間計測回路９０は、第１の時間Ｔ１ａ、第１の時間Ｔ１ｂ、および第１の時間Ｔ１ｃの各々を示す第１のデジタル値ＴＤＣ１を生成する。この例では、第１の時間計測回路９０は第１の時間を３回計測し、かつ３個の第１のデジタル値ＴＤＣ１を生成する。 The first time measurement circuit 90 measures the first time T1a from the timing tg2 to the timing tg4, the first time T1b from the timing tg2 to the timing tg6, and the first time T1c from the timing tg2 to the timing tg8. do. The first time measurement circuit 90 generates a first digital value TDC1 indicating each of the first time T1a, the first time T1b, and the first time T1c. In this example, the first time measurement circuit 90 measures the first time three times and generates three first digital values TDC1.
　第２の時間計測回路１００は、タイミングｔｇ２からタイミングｔｇ３までの第２の時間Ｔ２ａ、タイミングｔｇ２からタイミングｔｇ５までの第２の時間Ｔ２ｂ、タイミングｔｇ２からタイミングｔｇ７までの第２の時間Ｔ２ｃ、およびタイミングｔｇ２からタイミングｔｇ９までの第２の時間Ｔ２ｄを計測する。第２の時間計測回路１００は、第２の時間Ｔ２ａ、第２の時間Ｔ２ｂ、第２の時間Ｔ２ｃ、および第２の時間Ｔ２ｄの各々を示す第２のデジタル値ＴＤＣ２を生成する。この例では、第２の時間計測回路１００は第１の時間を４回計測し、かつ４個の第２のデジタル値ＴＤＣ２を生成する。 The second time measurement circuit 100 includes a second time T2a from timing tg2 to timing tg3, a second time T2b from timing tg2 to timing tg5, a second time T2c from timing tg2 to timing tg7, and timing. The second time T2d from tg2 to the timing tg9 is measured. The second time measurement circuit 100 generates a second digital value TDC2 indicating each of the second time T2a, the second time T2b, the second time T2c, and the second time T2d. In this example, the second time measurement circuit 100 measures the first time four times and generates four second digital values TDC2.
　ＣＰＵ３０は、第１の時間および第２の時間の２つ以上の組み合わせから選択された第１の時間および第２の時間の組み合わせに対応する第１のデジタル値ＴＤＣ１および第２のデジタル値ＴＤＣ２を使用することによりゼロクロス時間を算出してもよい。例えば、ＣＰＵ３０は、以下の方法を使用することによりゼロクロス時間を算出する。 The CPU 30 sets the first digital value TDC1 and the second digital value TDC2 corresponding to the combination of the first time and the second time selected from two or more combinations of the first time and the second time. The zero cross time may be calculated by use. For example, the CPU 30 calculates the zero cross time by using the following method.
　ＣＰＵ３０は、第１の時間と、その第１の時間に最も近い第２の時間とを含む組み合わせを生成する。第２の時間Ｔ２ａ、第２の時間Ｔ２ｂ、第２の時間Ｔ２ｃ、および第２の時間Ｔ２ｄのうち第２の時間Ｔ２ａが第１の時間Ｔ１ａに最も近い。そのため、ＣＰＵ３０は、第１の時間Ｔ１ａおよび第２の時間Ｔ２ａを含む組み合わせを生成する。 The CPU 30 generates a combination including the first time and the second time closest to the first time. Of the second time T2a, the second time T2b, the second time T2c, and the second time T2d, the second time T2a is the closest to the first time T1a. Therefore, the CPU 30 generates a combination including the first time T1a and the second time T2a.
　第２の時間Ｔ２ａ、第２の時間Ｔ２ｂ、第２の時間Ｔ２ｃ、および第２の時間Ｔ２ｄのうち第２の時間Ｔ２ｂが第１の時間Ｔ１ｂに最も近い。そのため、ＣＰＵ３０は、第１の時間Ｔ１ｂおよび第２の時間Ｔ２ｂを含む組み合わせを生成する。 Of the second time T2a, the second time T2b, the second time T2c, and the second time T2d, the second time T2b is the closest to the first time T1b. Therefore, the CPU 30 generates a combination including the first time T1b and the second time T2b.
　第２の時間Ｔ２ａ、第２の時間Ｔ２ｂ、第２の時間Ｔ２ｃ、および第２の時間Ｔ２ｄのうち第２の時間Ｔ２ｃが第１の時間Ｔ１ｃに最も近い。そのため、ＣＰＵ３０は、第１の時間Ｔ１ｃおよび第２の時間Ｔ２ｃを含む組み合わせを生成する。 Of the second time T2a, the second time T2b, the second time T2c, and the second time T2d, the second time T2c is the closest to the first time T1c. Therefore, the CPU 30 generates a combination including the first time T1c and the second time T2c.
　ＣＰＵ３０は、第１の時間と第２の時間との差の絶対値が所定値以内である組み合わせのみを生成してもよい。例えば、第２の時間Ｔ２ｄに最も近い第１の時間は第１の時間Ｔ１ｃである。ＣＰＵ３０は、第１の時間Ｔ１ｃと第２の時間Ｔ２ｄとの差の絶対値が所定値を超えると判断し、第２の時間Ｔ２ｄを含む組み合わせを生成しなくてもよい。 The CPU 30 may generate only combinations in which the absolute value of the difference between the first time and the second time is within a predetermined value. For example, the first time closest to the second time T2d is the first time T1c. The CPU 30 determines that the absolute value of the difference between the first time T1c and the second time T2d exceeds a predetermined value, and does not have to generate a combination including the second time T2d.
　２個以上の組み合わせが生成された場合、ＣＰＵ３０は、最も短い時間を含む組み合わせを選択する。例えば、ＣＰＵ３０は、第１の時間Ｔ１ａ、第１の時間Ｔ１ｂ、および第１の時間Ｔ１ｃのうち最も短い第１の時間Ｔ１ａを含む組み合わせを選択する。あるいは、ＣＰＵ３０は、第２の時間Ｔ２ａ、第２の時間Ｔ２ｂ、第２の時間Ｔ２ｃ、および第２の時間Ｔ２ｄのうち最も短い第２の時間Ｔ２ａを含む組み合わせを選択する。したがって、ＣＰＵ３０は、第１の時間Ｔ１ａおよび第２の時間Ｔ２ａを含む組み合わせを選択する。ＣＰＵ３０は、第１の時間Ｔ１ａに対応する第１のデジタル値ＴＤＣ１と、第２の時間Ｔ２ａに対応する第２のデジタル値ＴＤＣ２とを使用することによりゼロクロス時間を算出する。 When two or more combinations are generated, the CPU 30 selects the combination including the shortest time. For example, the CPU 30 selects a combination including the shortest first time T1a of the first time T1a, the first time T1b, and the first time T1c. Alternatively, the CPU 30 selects a combination that includes the shortest second time T2a of the second time T2a, the second time T2b, the second time T2c, and the second time T2d. Therefore, the CPU 30 selects a combination including the first time T1a and the second time T2a. The CPU 30 calculates the zero cross time by using the first digital value TDC1 corresponding to the first time T1a and the second digital value TDC2 corresponding to the second time T2a.
　図５を参照し、ノイズを原因とする時間計測の誤りを低減する方法を説明する。図５は、超音波計測装置１における各信号の波形を示す。スタートパルスＳＴＡＲＴ、エコー信号ＲＸａｃ２、第１の計測制御信号ＳＴＯＰ１、および第２の計測制御信号ＳＴＯＰ２の各々の波形が図５に示されている。図５における横方向は時間を示し、かつ図５における縦方向は各信号の電圧を示す。 With reference to FIG. 5, a method for reducing time measurement errors caused by noise will be described. FIG. 5 shows the waveform of each signal in the ultrasonic measuring device 1. The waveforms of the start pulse START, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG. The horizontal direction in FIG. 5 indicates time, and the vertical direction in FIG. 5 indicates the voltage of each signal.
　超音波計測装置１は、ＡＤ変換を連続的に実施せずに超音波信号のエコー信号に基づいて時間を直接計測する。エコー信号にノイズが含まれる場合、超音波計測装置１は、時間を正確に計測できない可能性がある。例えば、エコー信号ＲＸａｃ２は、図５に示すノイズＮ１を含む。ノイズＮ１の電圧が第１の閾値ＴＨｐを超えた場合、第１の比較器７０はハイレベルである第１の計測制御信号ＳＴＯＰ１を生成する。 The ultrasonic measuring device 1 directly measures the time based on the echo signal of the ultrasonic signal without continuously performing AD conversion. If the echo signal contains noise, the ultrasonic measuring device 1 may not be able to accurately measure the time. For example, the echo signal RXac2 includes the noise N1 shown in FIG. When the voltage of the noise N1 exceeds the first threshold value THp, the first comparator 70 generates the first measurement control signal STOP1 which is a high level.
　第１の時間計測回路９０は、第１の計測制御信号ＳＴＯＰ１に基づいて第１の時間Ｔ１ａを計測し、かつ第１の時間Ｔ１ａを示す第１のデジタル値ＴＤＣ１をＣＰＵ３０に出力する。ＣＰＵ３０がこの第１のデジタル値ＴＤＣ１を使用してゼロクロス時間を算出した場合、ＣＰＵ３０は誤った厚さを算出する。誤った厚さが算出されるのを避けるために超音波計測装置１は以下の処理を実行する。 The first time measurement circuit 90 measures the first time T1a based on the first measurement control signal STOP1 and outputs the first digital value TDC1 indicating the first time T1a to the CPU 30. When the CPU 30 uses this first digital value TDC1 to calculate the zero cross time, the CPU 30 calculates an erroneous thickness. The ultrasonic measuring device 1 performs the following processing in order to avoid calculating an erroneous thickness.
　第１の比較器７０は、エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐと一致する度に第１の計測制御信号ＳＴＯＰ１の電圧をハイレベルまたはローレベルに変化させる。第２の比較器８０は、エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎと一致する度に第２の計測制御信号ＳＴＯＰ２の電圧をハイレベルまたはローレベルに変化させる。 The first comparator 70 changes the voltage of the first measurement control signal STOP1 to a high level or a low level every time the voltage of the echo signal RXac2 matches the first threshold value THp. The second comparator 80 changes the voltage of the second measurement control signal STOP2 to a high level or a low level each time the voltage of the echo signal RXac2 matches the second threshold value THn.
　第１の時間計測回路９０は第１の時間を２回以上計測し、または第２の時間計測回路１００は第２の時間を２回以上計測する。ＣＰＵ３０は、第１の時間および第２の時間を互いに関連付けることにより第１の組み合わせおよび第２の組み合わせを生成する。第１の組み合わせおよび第２の組み合わせの各々は、第１の時間および第２の時間を含む。第１の組み合わせの第１の時間は第２の組み合わせの第１の時間と異なり、または第１の組み合わせの第２の時間は第２の組み合わせの第２の時間と異なる。 The first time measurement circuit 90 measures the first time twice or more, or the second time measurement circuit 100 measures the second time twice or more. The CPU 30 produces the first combination and the second combination by associating the first time and the second time with each other. Each of the first combination and the second combination includes a first time and a second time. The first time of the first combination is different from the first time of the second combination, or the second time of the first combination is different from the second time of the second combination.
　ＣＰＵ３０は、第１の組み合わせの第１の時間と第１の組み合わせの第２の時間との差である第１の差を算出する。ＣＰＵ３０は、第２の組み合わせの第１の時間と第２の組み合わせの第２の時間との差である第２の差を算出する。第１の差の絶対値が第２の差の絶対値よりも小さい場合、ＣＰＵ３０は、第１の組み合わせを使用することによりゼロクロス時間を算出する。第２の差の絶対値が第１の差の絶対値よりも小さい場合、ＣＰＵ３０は、第２の組み合わせを使用することによりゼロクロス時間を算出する。 The CPU 30 calculates the first difference, which is the difference between the first time of the first combination and the second time of the first combination. The CPU 30 calculates a second difference, which is the difference between the first time of the second combination and the second time of the second combination. If the absolute value of the first difference is smaller than the absolute value of the second difference, the CPU 30 calculates the zero cross time by using the first combination. If the absolute value of the second difference is smaller than the absolute value of the first difference, the CPU 30 calculates the zero cross time by using the second combination.
　図５に示す例では、第１の時間計測回路９０は少なくとも第１の時間Ｔ１ａおよび第１の時間Ｔ１ｂを計測する。図５に示す例では、第２の時間計測回路１００は少なくとも第２の時間Ｔ２ａを計測する。ＣＰＵ３０は、第１の時間Ｔ１ａおよび第２の時間Ｔ２ａを互いに関連付けることにより第１の組み合わせを生成する。第１の組み合わせは、第１の時間Ｔ１ａおよび第２の時間Ｔ２ａを含む。ＣＰＵ３０は、第１の時間Ｔ１ｂおよび第２の時間Ｔ２ａを互いに関連付けることにより第２の組み合わせを生成する。第２の組み合わせは、第１の時間Ｔ１ｂおよび第２の時間Ｔ２ａを含む。第１の組み合わせの第１の時間Ｔ１ａは第２の組み合わせの第１の時間Ｔ１ｂと異なる。 In the example shown in FIG. 5, the first time measurement circuit 90 measures at least the first time T1a and the first time T1b. In the example shown in FIG. 5, the second time measurement circuit 100 measures at least the second time T2a. The CPU 30 produces the first combination by associating the first time T1a and the second time T2a with each other. The first combination includes a first time T1a and a second time T2a. The CPU 30 produces a second combination by associating the first time T1b and the second time T2a with each other. The second combination includes a first time T1b and a second time T2a. The first time T1a of the first combination is different from the first time T1b of the second combination.
　ＣＰＵ３０は、第１の時間Ｔ１ａと第２の時間Ｔ２ａとの差である第１の差Ｔｄｉｆｆ１を算出する。ＣＰＵ３０は、第１の時間Ｔ１ｂと第２の時間Ｔ２ａとの差である第２の差Ｔｄｉｆｆ２を算出する。第２の差Ｔｄｉｆｆ２の絶対値は第１の差Ｔｄｉｆｆ１の絶対値よりも小さい。そのため、ＣＰＵ３０は、第２の組み合わせに含まれる第１の時間Ｔ１ｂおよび第２の時間Ｔ２ａを使用することによりゼロクロス時間を算出する。ＣＰＵ３０がノイズＮ１に基づいて計測された第１の時間Ｔ１ａを使用しないため、超音波計測装置１は、ノイズを原因とする時間計測の誤りを低減することができる。 The CPU 30 calculates the first difference Tdiff1, which is the difference between the first time T1a and the second time T2a. The CPU 30 calculates the second difference Tdiff2, which is the difference between the first time T1b and the second time T2a. The absolute value of the second difference Tdiff2 is smaller than the absolute value of the first difference Tdiff1. Therefore, the CPU 30 calculates the zero cross time by using the first time T1b and the second time T2a included in the second combination. Since the CPU 30 does not use the first time T1a measured based on the noise N1, the ultrasonic measuring device 1 can reduce the time measurement error caused by the noise.
　第１の時間および第２の時間を含む２個以上の組み合わせが生成された場合、ＣＰＵ３０は、第１の時間と第２の時間との差の絶対値が最も小さい組み合わせを選択してもよい。ＣＰＵ３０は、この方法を使用することにより、上記の例と同様に第１の時間Ｔ１ａの使用を避けることができる。 When two or more combinations including the first time and the second time are generated, the CPU 30 may select the combination having the smallest absolute value of the difference between the first time and the second time. .. By using this method, the CPU 30 can avoid using the first time T1a as in the above example.
　エコー信号ＲＸ、エコー信号ＲＸａｃ、エコー信号ＲＸａｃ１、およびエコー信号ＲＸａｃ２は、正弦波であり、かつ超音波振動子１０の共振周波数（駆動周波数）に応じた周期を持つ。そのため、図５に示すエコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎを超えたタイミングから、エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐを超えたタイミングまでの時間は、所定時間よりも短い。つまり、第１の時間と第２の時間との差は、所定時間よりも短い。例えば、所定時間は上記の周期の１／２である。第１の時間と第２の時間との差の絶対値が所定値以内である場合、ＣＰＵ３０は、その第１の時間および第２の時間を使用することによりゼロクロス時間を算出してもよい。その所定値は、超音波振動子１０の共振周波数に基づいて設定される。 The echo signal RX, echo signal RXac, echo signal RXac1 and echo signal RXac2 are sine waves and have a period corresponding to the resonance frequency (drive frequency) of the ultrasonic vibrator 10. Therefore, the time from the timing when the voltage of the echo signal RXac2 shown in FIG. 5 exceeds the second threshold value THn to the timing when the voltage of the echo signal RXac2 exceeds the first threshold value THp is shorter than the predetermined time. That is, the difference between the first time and the second time is shorter than the predetermined time. For example, the predetermined time is 1/2 of the above cycle. When the absolute value of the difference between the first time and the second time is within a predetermined value, the CPU 30 may calculate the zero cross time by using the first time and the second time. The predetermined value is set based on the resonance frequency of the ultrasonic vibrator 10.
　図６を参照し、ＣＰＵ３０がゼロクロス時間を算出する効果を説明する。図６は、超音波計測装置１における各信号の波形を示す。エコー信号ＲＸａｃ２、第１の計測制御信号ＳＴＯＰ１、および第２の計測制御信号ＳＴＯＰ２の各々の波形が図６に示されている。図６における横方向は時間を示し、かつ図６における縦方向は各信号の電圧を示す。 The effect of the CPU 30 calculating the zero cross time will be described with reference to FIG. FIG. 6 shows the waveform of each signal in the ultrasonic measuring device 1. The waveforms of the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG. The horizontal direction in FIG. 6 indicates time, and the vertical direction in FIG. 6 indicates the voltage of each signal.
　図６において、エコー信号ＲＸａｃ２の最大振幅が異なる２つの例が示されている。第１の例におけるエコー信号ＲＸａｃ２の最大振幅は、第２の例におけるエコー信号ＲＸａｃ２の最大振幅よりも大きい。第１の例において、第１の時間計測回路９０は第１の時間Ｔ１ａを計測し、かつ第２の時間計測回路１００は第２の時間Ｔ２ａを計測する。第２の例において、第１の時間計測回路９０は第１の時間Ｔ１ｂを計測し、かつ第２の時間計測回路１００は第２の時間Ｔ２ｂを計測する。 FIG. 6 shows two examples in which the maximum amplitude of the echo signal RXac2 is different. The maximum amplitude of the echo signal RXac2 in the first example is larger than the maximum amplitude of the echo signal RXac2 in the second example. In the first example, the first time measurement circuit 90 measures the first time T1a, and the second time measurement circuit 100 measures the second time T2a. In the second example, the first time measurement circuit 90 measures the first time T1b, and the second time measurement circuit 100 measures the second time T2b.
　第２の例においてエコー信号ＲＸａｃ２の振幅は第１の例におけるエコー信号ＲＸａｃ２の振幅よりも全体的に小さい。第２の例における第１の計測制御信号ＳＴＯＰ１の立ち上がりは第１の例における第１の計測制御信号ＳＴＯＰ１の立ち上がりよりも遅いため、第２の例における第１の時間Ｔ１ｂは第１の例における第１の時間Ｔ１ａよりも大きい。第２の例における第２の計測制御信号ＳＴＯＰ２の立ち上がりは第１の例における第２の計測制御信号ＳＴＯＰ２の立ち上がりよりも早いため、第２の例における第２の時間Ｔ２ｂは第１の例における第２の時間Ｔ２ａよりも小さい。 In the second example, the amplitude of the echo signal RXac2 is generally smaller than the amplitude of the echo signal RXac2 in the first example. Since the rise of the first measurement control signal STOP1 in the second example is slower than the rise of the first measurement control signal STOP1 in the first example, the first time T1b in the second example is in the first example. It is larger than the first time T1a. Since the rise of the second measurement control signal STOP2 in the second example is earlier than the rise of the second measurement control signal STOP2 in the first example, the second time T2b in the second example is in the first example. It is smaller than the second time T2a.
　第１の例における第１の時間Ｔ１ａおよび第２の時間Ｔ２ａの平均であるゼロクロス時間は、第２の例における第１の時間Ｔ１ｂおよび第２の時間Ｔ２ｂの平均であるゼロクロス時間と同じである。そのため、被検体の腐食等の理由でエコー信号ＲＸａｃ２の最大振幅が変化した場合であっても、ＣＰＵ３０はその変化の影響を抑制することができ、かつ被検体の厚さを高精度に算出することができる。 The zero cross time, which is the average of the first time T1a and the second time T2a in the first example, is the same as the zero cross time, which is the average of the first time T1b and the second time T2b in the second example. .. Therefore, even if the maximum amplitude of the echo signal RXac2 changes due to corrosion of the subject or the like, the CPU 30 can suppress the influence of the change and calculate the thickness of the subject with high accuracy. be able to.
　第１の実施形態の超音波計測装置１は、第１の時間および第２の時間に基づいてゼロクロス時間を算出する。そのため、超音波計測装置１は、超音波信号を使用する時間計測を高精度に実行することができる。その結果、超音波計測装置１は、被検体の厚さを高精度に算出することができる。超音波計測装置１は、簡易な構成を使用することにより時間計測を実行することができる。 The ultrasonic measuring device 1 of the first embodiment calculates the zero cross time based on the first time and the second time. Therefore, the ultrasonic measuring device 1 can perform time measurement using the ultrasonic signal with high accuracy. As a result, the ultrasonic measuring device 1 can calculate the thickness of the subject with high accuracy. The ultrasonic measuring device 1 can perform time measurement by using a simple configuration.
　第１の時間および第２の時間を含む２つ以上の組み合わせが生成された場合、超音波計測装置１は、第１の時間と第２の時間との差の絶対値が小さい組み合わせを使用することによりゼロクロス時間を算出する。そのため、超音波計測装置１は、ノイズを原因とする時間計測の誤りを低減することができる。 When two or more combinations including the first time and the second time are generated, the ultrasonic measuring device 1 uses the combination in which the absolute value of the difference between the first time and the second time is small. By doing so, the zero cross time is calculated. Therefore, the ultrasonic measuring device 1 can reduce an error in time measurement caused by noise.
　第１の時間計測回路９０および第２の時間計測回路１００は、ＴＤＣ回路である。そのため、ＡＤ変換を連続的に実施する装置の消費電力と比較して超音波計測装置１の消費電力が低減される。 The first time measurement circuit 90 and the second time measurement circuit 100 are TDC circuits. Therefore, the power consumption of the ultrasonic measuring device 1 is reduced as compared with the power consumption of the device that continuously performs the AD conversion.
　（第１の実施形態の変形例）
　本発明の第１の実施形態の変形例を説明する。ノイズを原因とする時間計測の誤りを低減するためには第１の閾値ＴＨｐ、第２の閾値ＴＨｎ、および第２の増幅器６０のゲインを調整することが効果的である。 (Modified example of the first embodiment)
A modified example of the first embodiment of the present invention will be described. It is effective to adjust the gains of the first threshold value THp, the second threshold value THn, and the second amplifier 60 in order to reduce the time measurement error caused by noise.
　超音波計測装置１はＡＤＣを有してなく、エコー信号ＲＸａｃ２の振幅を監視していない。そのため、第１の閾値ＴＨｐ、第２の閾値ＴＨｎ、および第２の増幅器６０のゲインの調整が困難である。第１の実施形態の変形例において、超音波計測装置１は第１の閾値ＴＨｐ、第２の閾値ＴＨｎ、および第２の増幅器６０のゲインを調整する機能を有する。 The ultrasonic measuring device 1 does not have an ADC and does not monitor the amplitude of the echo signal RXac2. Therefore, it is difficult to adjust the gains of the first threshold value THp, the second threshold value THn, and the second amplifier 60. In the modification of the first embodiment, the ultrasonic measuring device 1 has a function of adjusting the gains of the first threshold value THp, the second threshold value THn, and the second amplifier 60.
　ＣＰＵ３０（変更回路）は、第１の数および第２の数の少なくとも一方に基づいて第１の閾値ＴＨｐを変更し、かつ第１の数および第２の数の少なくとも一方に基づいて第２の閾値ＴＨｎを変更する。第１の数は、第１の時間計測回路９０が第１の時間を計測した回数を示す。第２の数は、第２の時間計測回路１００が第２の時間を計測した回数を示す。ＣＰＵ３０は、第１の数および第２の数の少なくとも一方に基づいて第２の増幅器６０のゲインを変更する。 The CPU 30 (change circuit) changes the first threshold THp based on at least one of the first number and the second number, and the second number is based on at least one of the first number and the second number. The threshold THn is changed. The first number indicates the number of times that the first time measuring circuit 90 measures the first time. The second number indicates the number of times that the second time measuring circuit 100 measures the second time. The CPU 30 changes the gain of the second amplifier 60 based on at least one of the first number and the second number.
　図４に示す例では、第１の時間計測回路９０は第１の時間を３回計測し、かつ３個の第１のデジタル値ＴＤＣ１を生成する。図４に示す例では、第２の時間計測回路１００は第１の時間を４回計測し、かつ４個の第２のデジタル値ＴＤＣ２を生成する。 In the example shown in FIG. 4, the first time measurement circuit 90 measures the first time three times and generates three first digital values TDC1. In the example shown in FIG. 4, the second time measurement circuit 100 measures the first time four times and generates four second digital values TDC2.
　以下では、第１のデジタル値ＴＤＣ１の数が、第１の数として使用される。以下では、第２のデジタル値ＴＤＣ２の数が、第２の数として使用される。 In the following, the number of the first digital value TDC1 is used as the first number. In the following, the number of the second digital value TDC2 is used as the second number.
　第１のデジタル値ＴＤＣ１の数および第２のデジタル値ＴＤＣ２の数が所定値よりも大きい場合、ＣＰＵ３０は、第１の閾値ＴＨｐを大きくし、かつ第２の閾値ＴＨｎを小さくする。これにより、第１の閾値ＴＨｐと基準電圧との差は大きくなり、かつ第２の閾値ＴＨｎと基準電圧との差は大きくなる。 When the number of the first digital value TDC1 and the number of the second digital value TDC2 are larger than the predetermined values, the CPU 30 increases the first threshold value THp and decreases the second threshold value THn. As a result, the difference between the first threshold value THp and the reference voltage becomes large, and the difference between the second threshold value THn and the reference voltage becomes large.
　第１のデジタル値ＴＤＣ１の数および第２のデジタル値ＴＤＣ２の数の少なくとも一方が所定値よりも小さい場合、ＣＰＵ３０は、第１の閾値ＴＨｐを小さくし、かつ第２の閾値ＴＨｎを大きくする。これにより、第１の閾値ＴＨｐと基準電圧との差は小さくなり、かつ第２の閾値ＴＨｎと基準電圧との差は小さくなる。 When at least one of the number of the first digital value TDC1 and the number of the second digital value TDC2 is smaller than a predetermined value, the CPU 30 decreases the first threshold value THp and increases the second threshold value THn. As a result, the difference between the first threshold value THp and the reference voltage becomes small, and the difference between the second threshold value THn and the reference voltage becomes small.
　第１の閾値ＴＨｐおよび第２の閾値ＴＨｎが調整された場合であっても第１のデジタル値ＴＤＣ１の数および第２のデジタル値ＴＤＣ２の数が所望の数にならない可能性がある。その場合、ＣＰＵ３０は、第２の増幅器６０のゲインを変更する。 Even when the first threshold value THp and the second threshold value THn are adjusted, the number of the first digital value TDC1 and the number of the second digital value TDC2 may not be the desired numbers. In that case, the CPU 30 changes the gain of the second amplifier 60.
　例えば、第１のデジタル値ＴＤＣ１の数および第２のデジタル値ＴＤＣ２の数が所定値よりも大きい場合、ＣＰＵ３０は、第２の増幅器６０のゲインを下げる。第１のデジタル値ＴＤＣ１の数および第２のデジタル値ＴＤＣ２の数の少なくとも一方が所定値よりも小さい場合、ＣＰＵ３０は、第２の増幅器６０のゲインを上げる。 For example, when the number of the first digital value TDC1 and the number of the second digital value TDC2 are larger than the predetermined values, the CPU 30 lowers the gain of the second amplifier 60. When at least one of the number of the first digital value TDC1 and the number of the second digital value TDC2 is smaller than a predetermined value, the CPU 30 increases the gain of the second amplifier 60.
　上記の例では、ＣＰＵ３０は、第１の数および第２の数に基づいて第１の閾値ＴＨｐおよび第２の閾値ＴＨｎを変更する。ＣＰＵ３０は、第１の数または第２の数のみに基づいて第１の閾値ＴＨｐを変更してもよい。ＣＰＵ３０は、第１の数または第２の数のみに基づいて第２の閾値ＴＨｎを変更してもよい。 In the above example, the CPU 30 changes the first threshold THp and the second threshold THn based on the first number and the second number. The CPU 30 may change the first threshold THp based only on the first number or the second number. The CPU 30 may change the second threshold THn based only on the first number or the second number.
　上記の例では、ＣＰＵ３０は、第１の数および第２の数に基づいて第２の増幅器６０のゲインを変更する。ＣＰＵ３０は、第１の数または第２の数のみに基づいて第２の増幅器６０のゲインを変更してもよい。ＣＰＵ３０は、第２の増幅器６０のゲインに代えて第１の増幅器５０のゲインを変更してもよい。 In the above example, the CPU 30 changes the gain of the second amplifier 60 based on the first number and the second number. The CPU 30 may change the gain of the second amplifier 60 based only on the first number or the second number. The CPU 30 may change the gain of the first amplifier 50 instead of the gain of the second amplifier 60.
　第１の実施形態の変形例において、ＣＰＵ３０は、第１の数および第２の数の少なくとも一方に基づいて第１の閾値ＴＨｐ、第２の閾値ＴＨｎ、および第２の増幅器６０のゲインを変更する。そのため、超音波計測装置１は、ノイズを原因とする時間計測の誤りを低減することができる。 In a modification of the first embodiment, the CPU 30 modifies the gains of the first threshold THp, the second threshold THn, and the second amplifier 60 based on at least one of the first number and the second number. do. Therefore, the ultrasonic measuring device 1 can reduce an error in time measurement caused by noise.
　（第２の実施形態）
　図７は、本発明の第２の実施形態の超音波計測装置１ａの構成を示す。図７に示す超音波計測装置１ａは、超音波振動子１０、駆動回路２０、ＣＰＵ３０（時間算出回路）、パルス遮断回路４０、第１の増幅器５０、第２の増幅器６０、第１の比較器７０、第２の比較器８０、時間計測回路９０ａ、および信号生成回路１１０を有する。図１に示す構成と同じ構成の説明を省略する。 (Second Embodiment)
FIG. 7 shows the configuration of the ultrasonic measuring device 1a according to the second embodiment of the present invention. The ultrasonic measuring device 1a shown in FIG. 7 includes an ultrasonic vibrator 10, a drive circuit 20, a CPU 30 (time calculation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a first comparator. It has 70, a second comparator 80, a time measuring circuit 90a, and a signal generation circuit 110. The description of the same configuration as that shown in FIG. 1 will be omitted.
　エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐと一致したとき、第１の比較器７０は、第１のタイミングを示す第１の比較信号ＣＯＭＰ１（第１の信号）を信号生成回路１１０に出力する。第１の比較信号ＣＯＭＰ１は、第１の実施形態における第１の計測制御信号ＳＴＯＰ１と同様である。 When the voltage of the echo signal RXac2 matches the first threshold value THp, the first comparator 70 outputs the first comparison signal COMP1 (first signal) indicating the first timing to the signal generation circuit 110. .. The first comparison signal COMP1 is the same as the first measurement control signal STOP1 in the first embodiment.
　エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎと一致したとき、第２の比較器８０は、第２のタイミングを示す第２の比較信号ＣＯＭＰ２（第２の信号）を信号生成回路１１０に出力する。第２の比較信号ＣＯＭＰ２は、第１の実施形態における第２の計測制御信号ＳＴＯＰ２と同様である。 When the voltage of the echo signal RXac2 matches the second threshold value THn, the second comparator 80 outputs the second comparison signal COMP2 (second signal) indicating the second timing to the signal generation circuit 110. .. The second comparison signal COMP2 is the same as the second measurement control signal STOP2 in the first embodiment.
　信号生成回路１１０は、第１のエッジおよび第２のエッジを持つ計測制御信号ＳＴＯＰ（第３の信号）を生成する。第１のエッジは、第１のタイミングと同期する。第２のエッジは、第２のタイミングと同期する。第１のエッジおよび第２のエッジの一方は立ち上がりエッジである。第１のエッジおよび第２のエッジの他方は立ち下がりエッジである。第１のエッジが立ち上がりエッジであるとき、第２のエッジは立ち下がりエッジである。第１のエッジが立ち下がりエッジであるとき、第２のエッジは立ち上がりエッジである。信号生成回路１１０は、生成された計測制御信号ＳＴＯＰを時間計測回路９０ａに出力する。 The signal generation circuit 110 generates a measurement control signal STOP (third signal) having a first edge and a second edge. The first edge is synchronized with the first timing. The second edge is synchronized with the second timing. One of the first edge and the second edge is a rising edge. The other of the first edge and the second edge is a falling edge. When the first edge is the rising edge, the second edge is the falling edge. When the first edge is a falling edge, the second edge is a rising edge. The signal generation circuit 110 outputs the generated measurement control signal STOP to the time measurement circuit 90a.
　時間計測回路９０ａは、ＴＤＣ回路である。時間計測回路９０ａは、スタートパルスＳＴＡＲＴが示すスタートタイミングから計測制御信号ＳＴＯＰの第１のエッジのタイミングまでの第１の時間を計測する。時間計測回路９０ａは、第１のエッジが計測制御信号ＳＴＯＰに現れたタイミングで、第１の時間を示す第１のデジタル値ＴＤＣ１を生成し、かつ保持する。時間計測回路９０ａは、生成された第１のデジタル値ＴＤＣ１をＣＰＵ３０に出力する。 The time measurement circuit 90a is a TDC circuit. The time measurement circuit 90a measures the first time from the start timing indicated by the start pulse START to the timing of the first edge of the measurement control signal STOP. The time measurement circuit 90a generates and holds the first digital value TDC1 indicating the first time at the timing when the first edge appears in the measurement control signal STOP. The time measurement circuit 90a outputs the generated first digital value TDC1 to the CPU 30.
　時間計測回路９０ａは、スタートパルスＳＴＡＲＴが示すスタートタイミングから計測制御信号ＳＴＯＰの第２のエッジのタイミングまでの第２の時間を計測する。時間計測回路９０ａは、第２のエッジが計測制御信号ＳＴＯＰに現れたタイミングで、第２の時間を示す第２のデジタル値ＴＤＣ２を生成し、かつ保持する。時間計測回路９０ａは、生成された第２のデジタル値ＴＤＣ２をＣＰＵ３０に出力する。 The time measurement circuit 90a measures the second time from the start timing indicated by the start pulse START to the timing of the second edge of the measurement control signal STOP. The time measurement circuit 90a generates and holds a second digital value TDC2 indicating the second time at the timing when the second edge appears in the measurement control signal STOP. The time measurement circuit 90a outputs the generated second digital value TDC2 to the CPU 30.
　図８を参照し、超音波計測装置１ａの動作を説明する。図８は、超音波計測装置１ａにおける各信号の波形を示す。パルスＴＸｐｒｅ、駆動信号ＴＸ、スタートパルスＳＴＡＲＴ、エコー信号ＲＸａｃ２、第１の比較信号ＣＯＭＰ１、第２の比較信号ＣＯＭＰ２、および計測制御信号ＳＴＯＰの各々の波形が図８に示されている。図８における横方向は時間を示し、かつ図８における縦方向は各信号の電圧を示す。図２に示す動作と同じ動作の説明を省略する。 The operation of the ultrasonic measuring device 1a will be described with reference to FIG. FIG. 8 shows the waveform of each signal in the ultrasonic measuring device 1a. The waveforms of the pulse TXpre, the drive signal TX, the start pulse START, the echo signal RXac2, the first comparison signal COMP1, the second comparison signal COMP2, and the measurement control signal STOP are shown in FIG. The horizontal direction in FIG. 8 indicates time, and the vertical direction in FIG. 8 indicates the voltage of each signal. The description of the same operation as that shown in FIG. 2 will be omitted.
　第１の比較器７０は、ローレベルまたはハイレベルを持つ２値信号を出力する。エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐよりも小さいとき、第１の比較器７０は、ローレベルである第１の比較信号ＣＯＭＰ１を出力する。エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐ以上であるとき、第１の比較器７０は、ハイレベルである第１の比較信号ＣＯＭＰ１を出力する。 The first comparator 70 outputs a binary signal having a low level or a high level. When the voltage of the echo signal RXac2 is smaller than the first threshold value THp, the first comparator 70 outputs the first comparison signal COMP1 which is a low level. When the voltage of the echo signal RXac2 is equal to or higher than the first threshold value THp, the first comparator 70 outputs the first comparison signal COMP1 which is a high level.
　第２の比較器８０は、ローレベルまたはハイレベルを持つ２値信号を出力する。エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎよりも小さいとき、第２の比較器８０は、ローレベルである第２の比較信号ＣＯＭＰ２を出力する。エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎ以上であるとき、第２の比較器８０は、ハイレベルである第２の比較信号ＣＯＭＰ２を出力する。 The second comparator 80 outputs a binary signal having a low level or a high level. When the voltage of the echo signal RXac2 is smaller than the second threshold value THn, the second comparator 80 outputs the second comparison signal COMP2 which is a low level. When the voltage of the echo signal RXac2 is equal to or higher than the second threshold value THn, the second comparator 80 outputs the second comparison signal COMP2 which is a high level.
　第２の比較信号ＣＯＭＰ２の電圧がローレベルからハイレベルに変化したとき、信号生成回路１１０は計測制御信号ＳＴＯＰの電圧をローレベルからハイレベルに変化させる。計測制御信号ＳＴＯＰは、第２の比較信号ＣＯＭＰ２の立ち上がりエッジと同期した立ち上がりエッジ（第２のエッジ）を持つ。第１の比較信号ＣＯＭＰ１の電圧がローレベルからハイレベルに変化したとき、信号生成回路１１０は計測制御信号ＳＴＯＰの電圧をハイレベルからローレベルに変化させる。計測制御信号ＳＴＯＰは、第１の比較信号ＣＯＭＰ１の立ち上がりエッジと同期した立ち下がりエッジ（第１のエッジ）を持つ。 When the voltage of the second comparison signal COMP2 changes from low level to high level, the signal generation circuit 110 changes the voltage of the measurement control signal STOP from low level to high level. The measurement control signal STOP has a rising edge (second edge) synchronized with the rising edge of the second comparison signal COMP2. When the voltage of the first comparison signal COMP1 changes from low level to high level, the signal generation circuit 110 changes the voltage of the measurement control signal STOP from high level to low level. The measurement control signal STOP has a falling edge (first edge) synchronized with the rising edge of the first comparison signal COMP1.
　第１の比較器７０が図８に示す第１の比較信号ＣＯＭＰ１を反転した信号を第１の比較信号ＣＯＭＰ１として出力してもよく、かつ第２の比較器８０が図８に示す第２の比較信号ＣＯＭＰ２を反転した信号を第２の比較信号ＣＯＭＰ２として出力してもよい。その場合、計測制御信号ＳＴＯＰは、第２の比較信号ＣＯＭＰ２の立ち下がりエッジと同期した立ち上がりエッジを持ち、かつ第１の比較信号ＣＯＭＰ１の立ち下がりエッジと同期した立ち下がりエッジを持つ。 The first comparator 70 may output a signal obtained by inverting the first comparison signal COMP1 shown in FIG. 8 as the first comparator signal COMP1, and the second comparator 80 may output a second comparison signal COMP1 shown in FIG. A signal obtained by inverting the comparison signal COMP2 may be output as the second comparison signal COMP2. In that case, the measurement control signal STOP has a rising edge synchronized with the falling edge of the second comparison signal COMP2 and has a falling edge synchronized with the falling edge of the first comparison signal COMP1.
　信号生成回路１１０は、図８に示す計測制御信号ＳＴＯＰを反転した信号を計測制御信号ＳＴＯＰとして生成してもよい。その場合、計測制御信号ＳＴＯＰは、第２の比較信号ＣＯＭＰ２の立ち上がりエッジと同期した立ち下がりエッジを持ち、かつ第１の比較信号ＣＯＭＰ１の立ち上がりエッジと同期した立ち上がりエッジを持つ。 The signal generation circuit 110 may generate a signal obtained by inverting the measurement control signal STOP shown in FIG. 8 as the measurement control signal STOP. In that case, the measurement control signal STOP has a falling edge synchronized with the rising edge of the second comparison signal COMP2 and has a rising edge synchronized with the rising edge of the first comparison signal COMP1.
　スタートパルスＳＴＡＲＴがＣＰＵ３０から出力されたとき、時間計測回路９０ａは時間の計測を開始する。時間計測回路９０ａは、計測制御信号ＳＴＯＰの立ち上がりエッジを検出し、かつその立ち上がりエッジのタイミングで第２のデジタル値ＴＤＣ２を保持する。図８に示す例では、時間計測回路９０ａは、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から計測制御信号ＳＴＯＰの立ち上がりエッジのタイミングｔｇ１０までの第２の時間Ｔ２を計測する。時間計測回路９０ａは、第２の時間Ｔ２を示す第２のデジタル値ＴＤＣ２をＣＰＵ３０に出力する。 When the start pulse START is output from the CPU 30, the time measurement circuit 90a starts measuring the time. The time measurement circuit 90a detects the rising edge of the measurement control signal STOP and holds the second digital value TDC2 at the timing of the rising edge. In the example shown in FIG. 8, the time measurement circuit 90a measures the second time T2 from the timing tg2 of the rising edge of the start pulse START to the timing tg10 of the rising edge of the measurement control signal STOP. The time measurement circuit 90a outputs a second digital value TDC2 indicating the second time T2 to the CPU 30.
　時間計測回路９０ａは、計測制御信号ＳＴＯＰの立ち下がりエッジを検出し、かつその立ち下がりエッジのタイミングで第１のデジタル値ＴＤＣ１を保持する。図８に示す例では、時間計測回路９０ａは、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から計測制御信号ＳＴＯＰの立ち下がりエッジのタイミングｔｇ１１までの第１の時間Ｔ１を計測する。時間計測回路９０ａは、第１の時間Ｔ１を示す第１のデジタル値ＴＤＣ１をＣＰＵ３０に出力する。 The time measurement circuit 90a detects the falling edge of the measurement control signal STOP and holds the first digital value TDC1 at the timing of the falling edge. In the example shown in FIG. 8, the time measurement circuit 90a measures the first time T1 from the timing tg2 of the rising edge of the start pulse START to the timing tg11 of the falling edge of the measurement control signal STOP. The time measurement circuit 90a outputs the first digital value TDC1 indicating the first time T1 to the CPU 30.
　ＣＰＵ３０がゼロクロス時間および被検体の厚さを算出する方法は、第１の実施形態における方法と同じである。 The method by which the CPU 30 calculates the zero cross time and the thickness of the subject is the same as the method in the first embodiment.
　第１の実施形態の超音波計測装置１は、第１の時間計測回路９０および第２の時間計測回路１００を有する。一方、第２の実施形態の超音波計測装置１ａは、時間計測回路９０ａを有する。第２の実施形態において時間計測回路の数が減るため、システムが簡素化される。 The ultrasonic measuring device 1 of the first embodiment has a first time measuring circuit 90 and a second time measuring circuit 100. On the other hand, the ultrasonic measuring device 1a of the second embodiment has a time measuring circuit 90a. In the second embodiment, the number of time measuring circuits is reduced, which simplifies the system.
　（第３の実施形態）
　本発明の第３の実施形態を説明する。被検体が薄い場合、超音波振動子１０と被検体との間に緩衝材が挿入されてもよい。その場合、Ｅｃｈｏ－ｔｏ－Ｅｃｈｏ計測と呼ばれる方法が使用されてもよい。図９を参照し、Ｅｃｈｏ－ｔｏ－Ｅｃｈｏ計測の原理を説明する。 (Third Embodiment)
A third embodiment of the present invention will be described. When the subject is thin, a cushioning material may be inserted between the ultrasonic transducer 10 and the subject. In that case, a method called Echo-to-Echo measurement may be used. The principle of Echo-to-Echo measurement will be described with reference to FIG.
　図９は、超音波信号が伝搬する時間を示す。図９において、超音波振動子１０、被検体２００、および緩衝材２１０の断面が示されている。超音波振動子１０から送信された超音波信号は被検体の表面（上面）で反射し、かつ超音波振動子１０によって受信される。この場合、駆動信号ＴＸが超音波振動子１０に出力されたタイミングからエコー信号ＲＸが超音波振動子１０から出力されたタイミングまでの時間Ｔｔｏｆ１は以下の式（６）で表される。
　　Ｔｔｏｆ１＝Ｔｍ０１＋Ｔｍ０２＋Ｔｍ１１＋Ｔｍ１２　　（６） FIG. 9 shows the time for the ultrasonic signal to propagate. In FIG. 9, a cross section of the ultrasonic vibrator 10, the subject 200, and the cushioning material 210 is shown. The ultrasonic signal transmitted from the ultrasonic vibrator 10 is reflected on the surface (upper surface) of the subject and is received by the ultrasonic vibrator 10. In this case, the time Ttof1 from the timing when the drive signal TX is output to the ultrasonic vibrator 10 to the timing when the echo signal RX is output from the ultrasonic vibrator 10 is expressed by the following equation (6).
Ttof1 = Tm01 + Tm02 + Tm11 + Tm12 (6)
　時間Ｔｔｏｆ１は、式（６）における時間Ｔｍ０１、時間Ｔｍ０２、時間Ｔｍ１１、および時間Ｔｍ１２を含む。時間Ｔｍ０１は、駆動信号ＴＸが超音波振動子１０に出力されたタイミングから、超音波振動子１０によって生成された超音波信号が緩衝材２１０に到達するタイミングまでの時間を示す。時間Ｔｍ０２は、超音波振動子１０が被検体２００の表面からの反射信号を受信したタイミングからエコー信号ＲＸが超音波振動子１０から出力されたタイミングまでの時間を示す。時間Ｔｍ１１は、超音波信号が緩衝材２１０に到達したタイミングから超音波信号が被検体２００の表面に到達するタイミングまでの時間を示す。時間Ｔｍ１２は、超音波信号が被検体２００の表面で反射したタイミングから反射信号が超音波振動子１０に到達するタイミングまでの時間を示す。 Time Ttof1 includes time Tm01, time Tm02, time Tm11, and time Tm12 in the formula (6). The time Tm01 indicates the time from the timing when the drive signal TX is output to the ultrasonic vibrator 10 to the timing when the ultrasonic signal generated by the ultrasonic vibrator 10 reaches the cushioning material 210. The time Tm02 indicates the time from the timing when the ultrasonic vibrator 10 receives the reflected signal from the surface of the subject 200 to the timing when the echo signal RX is output from the ultrasonic vibrator 10. The time Tm11 indicates the time from the timing when the ultrasonic signal reaches the cushioning material 210 to the timing when the ultrasonic signal reaches the surface of the subject 200. The time Tm12 indicates the time from the timing when the ultrasonic signal is reflected on the surface of the subject 200 to the timing when the reflected signal reaches the ultrasonic vibrator 10.
　一方、超音波振動子１０から送信された超音波信号は被検体の裏面（下面）で反射し、かつ超音波振動子１０によって受信される。この場合、駆動信号ＴＸが超音波振動子１０に出力されたタイミングからエコー信号ＲＸが超音波振動子１０から出力されたタイミングまでの時間Ｔｔｏｆ２は以下の式（７）で表される。
　　Ｔｔｏｆ２＝Ｔｍ０１＋Ｔｍ０２＋Ｔｍ１１＋Ｔｍ１２＋Ｔｍ２１＋Ｔｍ２２　　（７） On the other hand, the ultrasonic signal transmitted from the ultrasonic vibrator 10 is reflected on the back surface (lower surface) of the subject and is received by the ultrasonic vibrator 10. In this case, the time Ttof2 from the timing when the drive signal TX is output to the ultrasonic vibrator 10 to the timing when the echo signal RX is output from the ultrasonic vibrator 10 is expressed by the following equation (7).
Ttof2 = Tm01 + Tm02 + Tm11 + Tm12 + Tm21 + Tm22 (7)
　時間Ｔｔｏｆ２は、式（７）における時間Ｔｍ０１、時間Ｔｍ０２、時間Ｔｍ１１、時間Ｔｍ１２、時間Ｔｍ２１、および時間Ｔｍ２２を含む。式（７）における時間Ｔｍ０１、時間Ｔｍ０２、時間Ｔｍ１１、時間Ｔｍ１２は、式（６）における時間Ｔｍ０１、時間Ｔｍ０２、時間Ｔｍ１１、時間Ｔｍ１２とそれぞれ同じである。時間Ｔｍ２１は、超音波信号が被検体２００の表面に到達したタイミングから超音波信号が被検体２００の裏面に到達するタイミングまでの時間を示す。時間Ｔｍ２２は、超音波信号が被検体２００の裏面で反射したタイミングから反射信号が緩衝材２１０に到達するタイミングまでの時間を示す。 Time Ttof2 includes time Tm01, time Tm02, time Tm11, time Tm12, time Tm21, and time Tm22 in the formula (7). The time Tm01, time Tm02, time Tm11, and time Tm12 in the formula (7) are the same as the time Tm01, time Tm02, time Tm11, and time Tm12 in the formula (6), respectively. The time Tm21 indicates the time from the timing when the ultrasonic signal reaches the front surface of the subject 200 to the timing when the ultrasonic signal reaches the back surface of the subject 200. The time Tm22 indicates the time from the timing when the ultrasonic signal is reflected on the back surface of the subject 200 to the timing when the reflected signal reaches the cushioning material 210.
　以下の式（８）は、時間Ｔｔｏｆ１と時間Ｔｔｏｆ２との差を表す。
　　Ｔｔｏｆ２－Ｔｔｏｆ１＝Ｔｍ２１＋Ｔｍ２２　　（８） The following equation (8) represents the difference between the time Ttof1 and the time Ttof2.
Ttof2-Ttof1 = Tm21 + Tm22 (8)
　したがって、第３の実施形態の超音波計測装置は、時間Ｔｔｏｆ１および時間Ｔｔｏｆ２を計測し、かつ時間Ｔｔｏｆ１と時間Ｔｔｏｆ２との差を算出することにより、超音波信号が被検体２００内で伝搬する時間を得ることができる。 Therefore, the ultrasonic measuring device of the third embodiment measures the time Ttof1 and the time Ttof2, and calculates the difference between the time Ttof1 and the time Ttof2 to calculate the time for the ultrasonic signal to propagate in the subject 200. Can be obtained.
　図１０は、第３の実施形態の超音波計測装置１ｂの構成を示す。図１０に示す超音波計測装置１ｂは、超音波振動子１０、駆動回路２０、ＣＰＵ３０ｂ（時間算出回路）、パルス遮断回路４０、第１の増幅器５０、第２の増幅器６０、第１の比較器７０、第２の比較器８０、第１の時間計測回路９０ｂ、第２の時間計測回路１００ｂ、および信号生成回路１１０ｂを有する。図１に示す構成と同じ構成の説明を省略する。 FIG. 10 shows the configuration of the ultrasonic measuring device 1b according to the third embodiment. The ultrasonic measuring device 1b shown in FIG. 10 includes an ultrasonic vibrator 10, a drive circuit 20, a CPU 30b (time calculation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a first comparator. It has 70, a second comparator 80, a first time measuring circuit 90b, a second time measuring circuit 100b, and a signal generation circuit 110b. The description of the same configuration as that shown in FIG. 1 will be omitted.
　ＣＰＵ３０ｂは、パルスＴＸｐｒｅを生成し、かつパルスＴＸｐｒｅを駆動回路２０に出力する。 The CPU 30b generates a pulse TXpre and outputs the pulse TXpre to the drive circuit 20.
　エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐと一致したとき、第１の比較器７０は、第１のタイミングを示す第１の比較信号ＣＯＭＰ１を信号生成回路１１０に出力する。第１の比較信号ＣＯＭＰ１は、第１の実施形態における第１の計測制御信号ＳＴＯＰ１と同様である。 When the voltage of the echo signal RXac2 matches the first threshold value THp, the first comparator 70 outputs the first comparison signal COMP1 indicating the first timing to the signal generation circuit 110. The first comparison signal COMP1 is the same as the first measurement control signal STOP1 in the first embodiment.
　エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎと一致したとき、第２の比較器８０は、第２のタイミングを示す第２の比較信号ＣＯＭＰ２を信号生成回路１１０に出力する。第２の比較信号ＣＯＭＰ２は、第１の実施形態における第２の計測制御信号ＳＴＯＰ２と同様である。 When the voltage of the echo signal RXac2 matches the second threshold value THn, the second comparator 80 outputs the second comparison signal COMP2 indicating the second timing to the signal generation circuit 110. The second comparison signal COMP2 is the same as the second measurement control signal STOP2 in the first embodiment.
　第１の比較器７０は、エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐと一致する度に第１の比較信号ＣＯＭＰ１の電圧をハイレベルまたはローレベルに変化させる。第２の比較器８０は、エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎと一致する度に第２の比較信号ＣＯＭＰ２の電圧をハイレベルまたはローレベルに変化させる。 The first comparator 70 changes the voltage of the first comparator signal COMP1 to a high level or a low level each time the voltage of the echo signal RXac2 matches the first threshold value THp. The second comparator 80 changes the voltage of the second comparator signal COMP2 to a high level or a low level each time the voltage of the echo signal RXac2 matches the second threshold value THn.
　信号生成回路１１０ｂは、第１の期間において第１のエッジおよび第２のエッジを持つ第１の計測制御信号ＳＴＯＰ１を生成する。第１のエッジは、第１のタイミングと同期する。第２のエッジは、第２のタイミングと同期する。第１のエッジおよび第２のエッジの一方は立ち上がりエッジである。第１のエッジおよび第２のエッジの他方は立ち下がりエッジである。第１のエッジが立ち上がりエッジであるとき、第２のエッジは立ち下がりエッジである。第１のエッジが立ち下がりエッジであるとき、第２のエッジは立ち上がりエッジである。 The signal generation circuit 110b generates the first measurement control signal STOP1 having the first edge and the second edge in the first period. The first edge is synchronized with the first timing. The second edge is synchronized with the second timing. One of the first edge and the second edge is a rising edge. The other of the first edge and the second edge is a falling edge. When the first edge is the rising edge, the second edge is the falling edge. When the first edge is a falling edge, the second edge is a rising edge.
　信号生成回路１１０ｂは、第１の期間よりも後の第２の期間において第３のエッジおよび第４のエッジを持つ第２の計測制御信号ＳＴＯＰ２を生成する。第３のエッジは、第１のタイミングと同期する。第４のエッジは、第２のタイミングと同期する。第３のエッジおよび第４のエッジの一方は立ち上がりエッジである。第３のエッジおよび第４のエッジの他方は立ち下がりエッジである。第３のエッジが立ち上がりエッジであるとき、第４のエッジは立ち下がりエッジである。第３のエッジが立ち下がりエッジであるとき、第４のエッジは立ち上がりエッジである。 The signal generation circuit 110b generates a second measurement control signal STOP2 having a third edge and a fourth edge in a second period after the first period. The third edge synchronizes with the first timing. The fourth edge synchronizes with the second timing. One of the third edge and the fourth edge is a rising edge. The other of the third edge and the fourth edge is a falling edge. When the third edge is the rising edge, the fourth edge is the falling edge. When the third edge is a falling edge, the fourth edge is a rising edge.
　第１の期間において、被検体２００の表面で反射した超音波信号のエコー信号ＲＸに基づいて時間計測が実行される。第２の期間において、被検体２００の裏面で反射した超音波信号のエコー信号ＲＸに基づいて時間計測が実行される。信号生成回路１１０ｂは、ＣＰＵ３０ｂから出力された制御信号ＳＷに基づいて第１の期間における動作と第２の期間における動作とを切り替える。 In the first period, time measurement is performed based on the echo signal RX of the ultrasonic signal reflected on the surface of the subject 200. In the second period, time measurement is performed based on the echo signal RX of the ultrasonic signal reflected on the back surface of the subject 200. The signal generation circuit 110b switches between the operation in the first period and the operation in the second period based on the control signal SW output from the CPU 30b.
　ＣＰＵ３０ｂは、第１の期間と第２の期間とが切り替わるタイミングで制御信号ＳＷを生成し、かつ制御信号ＳＷを信号生成回路１１０ｂに出力する。例えば、最初に第２の実施形態における時間計測と同様の時間計測が実行される。この時間計測において、図８に示す第１の時間Ｔ１および第２の時間Ｔ２が計測される。ＣＰＵ３０ｂは、この結果に基づいて第１の期間と第２の期間とが切り替わるタイミングを設定してもよい。 The CPU 30b generates a control signal SW at the timing when the first period and the second period are switched, and outputs the control signal SW to the signal generation circuit 110b. For example, first, the same time measurement as the time measurement in the second embodiment is performed. In this time measurement, the first time T1 and the second time T2 shown in FIG. 8 are measured. The CPU 30b may set the timing at which the first period and the second period are switched based on this result.
　制御信号ＳＷがＣＰＵ３０ｂから出力される前、信号生成回路１１０ｂは第１の計測制御信号ＳＴＯＰ１を生成し、かつ第１の計測制御信号ＳＴＯＰ１を第１の時間計測回路９０ｂに出力する。制御信号ＳＷがＣＰＵ３０ｂから出力された後、信号生成回路１１０ｂは第２の計測制御信号ＳＴＯＰ２を生成し、かつ第２の計測制御信号ＳＴＯＰ２を第２の時間計測回路１００ｂに出力する。 Before the control signal SW is output from the CPU 30b, the signal generation circuit 110b generates the first measurement control signal STOP1 and outputs the first measurement control signal STOP1 to the first time measurement circuit 90b. After the control signal SW is output from the CPU 30b, the signal generation circuit 110b generates the second measurement control signal STOP2 and outputs the second measurement control signal STOP2 to the second time measurement circuit 100b.
　ＣＰＵ３０ｂは、第１の時間計測回路９０ｂが計測する第１の時間および第２の時間計測回路１００ｂが計測する第２の時間の各々のスタートタイミングを示すスタートパルスＳＴＡＲＴを第１の時間計測回路９０ｂおよび第２の時間計測回路１００ｂに出力する。 The CPU 30b sets a start pulse START indicating the start timing of each of the first time measured by the first time measuring circuit 90b and the second time measured by the second time measuring circuit 100b to the first time measuring circuit 90b and the first time measuring circuit 90b. Output to the second time measurement circuit 100b.
　第１の時間計測回路９０ｂおよび第２の時間計測回路１００ｂは、ＴＤＣ回路である。第１の時間計測回路９０ｂは、スタートパルスＳＴＡＲＴが示すスタートタイミングから第１の計測制御信号ＳＴＯＰ１の第１のエッジのタイミングまでの第１の時間を計測する。第１の時間計測回路９０ｂは、第１のエッジが第１の計測制御信号ＳＴＯＰ１に現れたタイミングで、第１の時間を示す第１のデジタル値ＴＤＣ１１を生成し、かつ保持する。第１の時間計測回路９０ｂは、生成された第１のデジタル値ＴＤＣ１１をＣＰＵ３０に出力する。 The first time measurement circuit 90b and the second time measurement circuit 100b are TDC circuits. The first time measurement circuit 90b measures the first time from the start timing indicated by the start pulse START to the timing of the first edge of the first measurement control signal STOP1. The first time measurement circuit 90b generates and holds the first digital value TDC11 indicating the first time at the timing when the first edge appears in the first measurement control signal STOP1. The first time measurement circuit 90b outputs the generated first digital value TDC 11 to the CPU 30.
　第１の時間計測回路９０ｂは、スタートパルスＳＴＡＲＴが示すスタートタイミングから第１の計測制御信号ＳＴＯＰ１の第２のエッジのタイミングまでの第２の時間を計測する。第１の時間計測回路９０ｂは、第２のエッジが第１の計測制御信号ＳＴＯＰ１に現れたタイミングで、第２の時間を示す第２のデジタル値ＴＤＣ２１を生成し、かつ保持する。第１の時間計測回路９０ｂは、生成された第２のデジタル値ＴＤＣ２１をＣＰＵ３０に出力する。 The first time measurement circuit 90b measures the second time from the start timing indicated by the start pulse START to the timing of the second edge of the first measurement control signal STOP1. The first time measurement circuit 90b generates and holds a second digital value TDC21 indicating the second time at the timing when the second edge appears in the first measurement control signal STOP1. The first time measurement circuit 90b outputs the generated second digital value TDC 21 to the CPU 30.
　したがって、第１の時間計測回路９０ｂは、第１の期間において第１の時間および第２の時間を計測する。第１の時間計測回路９０ｂは、第１の期間において、第１の時間を示す第１のデジタル値ＴＤＣ１１と、第２の時間を示す第２のデジタル値ＴＤＣ２１とを生成する。 Therefore, the first time measurement circuit 90b measures the first time and the second time in the first period. The first time measurement circuit 90b generates a first digital value TDC11 indicating a first time and a second digital value TDC21 indicating a second time in the first period.
　第２の時間計測回路１００ｂは、スタートパルスＳＴＡＲＴが示すスタートタイミングから第２の計測制御信号ＳＴＯＰ２の第３のエッジのタイミングまでの第１の時間を計測する。第２の時間計測回路１００ｂは、第３のエッジが第２の計測制御信号ＳＴＯＰ２に現れたタイミングで、第１の時間を示す第１のデジタル値ＴＤＣ１２を生成し、かつ保持する。第２の時間計測回路１００ｂは、生成された第１のデジタル値ＴＤＣ１２をＣＰＵ３０に出力する。 The second time measurement circuit 100b measures the first time from the start timing indicated by the start pulse START to the timing of the third edge of the second measurement control signal STOP2. The second time measurement circuit 100b generates and holds the first digital value TDC12 indicating the first time at the timing when the third edge appears in the second measurement control signal STOP2. The second time measurement circuit 100b outputs the generated first digital value TDC 12 to the CPU 30.
　第２の時間計測回路１００ｂは、スタートパルスＳＴＡＲＴが示すスタートタイミングから第２の計測制御信号ＳＴＯＰ２の第４のエッジのタイミングまでの第２の時間を計測する。第２の時間計測回路１００ｂは、第４のエッジが第２の計測制御信号ＳＴＯＰ２に現れたタイミングで、第２の時間を示す第２のデジタル値ＴＤＣ２２を生成し、かつ保持する。第２の時間計測回路１００ｂは、生成された第２のデジタル値ＴＤＣ２２をＣＰＵ３０に出力する。 The second time measurement circuit 100b measures the second time from the start timing indicated by the start pulse START to the timing of the fourth edge of the second measurement control signal STOP2. The second time measurement circuit 100b generates and holds a second digital value TDC22 indicating the second time at the timing when the fourth edge appears in the second measurement control signal STOP2. The second time measurement circuit 100b outputs the generated second digital value TDC 22 to the CPU 30.
　したがって、第２の時間計測回路１００ｂは、第２の期間において第１の時間および第２の時間を計測する。第２の時間計測回路１００ｂは、第２の期間において、第１の時間を示す第１のデジタル値ＴＤＣ１２と、第２の時間を示す第２のデジタル値ＴＤＣ２２とを生成する。 Therefore, the second time measurement circuit 100b measures the first time and the second time in the second period. The second time measurement circuit 100b generates a first digital value TDC 12 indicating the first time and a second digital value TDC 22 indicating the second time in the second period.
　ＣＰＵ３０ｂは、第１の時間計測回路９０ｂから出力された第１のデジタル値ＴＤＣ１１および第２のデジタル値ＴＤＣ２１を受信し、かつ第２の時間計測回路１００ｂから出力された第１のデジタル値ＴＤＣ１２および第２のデジタル値ＴＤＣ２２を受信する。ＣＰＵ３０ｂは、第１のデジタル値ＴＤＣ１１および第２のデジタル値ＴＤＣ２１に基づいて第１のゼロクロス時間を算出する。第１のゼロクロス時間は、スタートタイミングから被検体２００の表面で反射した超音波信号のエコー信号ＲＸａｃ２の電圧が基準電圧と一致したタイミングまでの時間を示す。 The CPU 30b receives the first digital value TDC11 and the second digital value TDC21 output from the first time measurement circuit 90b, and the first digital value TDC12 and the first digital value TDC12 output from the second time measurement circuit 100b. The second digital value TDC22 is received. The CPU 30b calculates the first zero cross time based on the first digital value TDC 11 and the second digital value TDC 21. The first zero cross time indicates the time from the start timing to the timing when the voltage of the echo signal RXac2 of the ultrasonic signal reflected on the surface of the subject 200 matches the reference voltage.
　ＣＰＵ３０ｂは、第１のデジタル値ＴＤＣ１２および第２のデジタル値ＴＤＣ２２に基づいて第２のゼロクロス時間を算出する。第２のゼロクロス時間は、スタートタイミングから被検体２００の裏面で反射した超音波信号のエコー信号ＲＸａｃ２の電圧が基準電圧と一致したタイミングまでの時間を示す。 The CPU 30b calculates the second zero cross time based on the first digital value TDC12 and the second digital value TDC22. The second zero cross time indicates the time from the start timing to the timing when the voltage of the echo signal RXac2 of the ultrasonic signal reflected on the back surface of the subject 200 matches the reference voltage.
　第１のゼロクロス時間および第２のゼロクロス時間を算出する方法は、第１の実施形態においてゼロクロス時間を算出する方法と同じである。ＣＰＵ３０ｂは、第１のゼロクロス時間と第２のゼロクロス時間との差に基づいて被検体の厚さを算出する。その差は、式（８）における時間Ｔｔｏｆ１と時間Ｔｔｏｆ２との差に対応する。 The method of calculating the first zero crossing time and the second zero crossing time is the same as the method of calculating the zero crossing time in the first embodiment. The CPU 30b calculates the thickness of the subject based on the difference between the first zero crossing time and the second zero crossing time. The difference corresponds to the difference between the time Ttof1 and the time Ttof2 in the equation (8).
　図１１を参照し、超音波計測装置１ｂの動作を説明する。図１１は、超音波計測装置１ｂにおける各信号の波形を示す。パルスＴＸｐｒｅ、駆動信号ＴＸ、スタートパルスＳＴＡＲＴ、制御信号ＳＷ、エコー信号ＲＸａｃ２、第１の計測制御信号ＳＴＯＰ１、および第２の計測制御信号ＳＴＯＰ２の各々の波形が図１１に示されている。図１１における横方向は時間を示し、かつ図１１における縦方向は各信号の電圧を示す。図２に示す動作と同じ動作の説明を省略する。 The operation of the ultrasonic measuring device 1b will be described with reference to FIG. FIG. 11 shows the waveform of each signal in the ultrasonic measuring device 1b. The waveforms of the pulse TXpre, the drive signal TX, the start pulse START, the control signal SW, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG. The horizontal direction in FIG. 11 indicates time, and the vertical direction in FIG. 11 indicates the voltage of each signal. The description of the same operation as that shown in FIG. 2 will be omitted.
　エコー信号ＲＸａｃ２は、成分ＲＸ３および成分ＲＸ４を含む。成分ＲＸ３は、被検体の表面で反射した超音波信号に基づいて生成される。成分ＲＸ４は、被検体の裏面で反射した超音波信号に基づいて生成される。成分ＲＸ４の最大振幅は、成分ＲＸ３の最大振幅よりも小さい。 The echo signal RXac2 includes the component RX3 and the component RX4. The component RX3 is generated based on the ultrasonic signal reflected on the surface of the subject. The component RX4 is generated based on the ultrasonic signal reflected on the back surface of the subject. The maximum amplitude of the component RX4 is smaller than the maximum amplitude of the component RX3.
　ＣＰＵ３０ｂは、タイミングｔｇ１でパルスＴＸｐｒｅを駆動回路２０に出力する。タイミングｔｇ１から所定の時間Ｔｓｔｏｆｆが経過したタイミングｔｇ２において、ＣＰＵ３０ｂはスタートパルスＳＴＡＲＴを第１の時間計測回路９０ｂおよび第２の時間計測回路１００ｂに出力する。信号生成回路１１０ｂは第１の計測制御信号ＳＴＯＰ１の出力を開始する。信号生成回路１１０ｂは第２の計測制御信号ＳＴＯＰ２の出力を停止している。 The CPU 30b outputs the pulse TXpre to the drive circuit 20 at the timing tg1. At the timing tg2 in which the predetermined time Tstoff has elapsed from the timing tg1, the CPU 30b outputs the start pulse START to the first time measurement circuit 90b and the second time measurement circuit 100b. The signal generation circuit 110b starts the output of the first measurement control signal STOP1. The signal generation circuit 110b has stopped the output of the second measurement control signal STOP2.
　エコー信号ＲＸａｃ２（成分ＲＸ３）の電圧が増加し、かつ第２の閾値ＴＨｎと一致したとき、信号生成回路１１０ｂは、第２の比較器８０から出力された第２の比較信号ＣＯＭＰ２に基づいて第１の計測制御信号ＳＴＯＰ１の電圧をローレベルからハイレベルに変化させる。第１の計測制御信号ＳＴＯＰ１は、第２の比較信号ＣＯＭＰ２の立ち上がりエッジと同期した立ち上がりエッジ（第２のエッジ）を持つ。エコー信号ＲＸａｃ２（成分ＲＸ３）の電圧が増加し、かつ第１の閾値ＴＨｐと一致したとき、信号生成回路１１０ｂは、第１の比較器７０から出力された第１の比較信号ＣＯＭＰ１に基づいて第１の計測制御信号ＳＴＯＰ１の電圧をハイレベルからローレベルに変化させる。第１の計測制御信号ＳＴＯＰ１は、第１の比較信号ＣＯＭＰ１の立ち上がりエッジと同期した立ち下がりエッジ（第１のエッジ）を持つ。 When the voltage of the echo signal RXac2 (component RX3) increases and matches the second threshold value THn, the signal generation circuit 110b is based on the second comparison signal COMP2 output from the second comparator 80. The voltage of the measurement control signal STOP1 of 1 is changed from a low level to a high level. The first measurement control signal STOP1 has a rising edge (second edge) synchronized with the rising edge of the second comparison signal COMP2. When the voltage of the echo signal RXac2 (component RX3) increases and matches the first threshold value THp, the signal generation circuit 110b is based on the first comparison signal COMP1 output from the first comparator 70. The voltage of the measurement control signal STOP1 of 1 is changed from a high level to a low level. The first measurement control signal STOP1 has a falling edge (first edge) synchronized with the rising edge of the first comparison signal COMP1.
　スタートパルスＳＴＡＲＴがＣＰＵ３０ｂから出力されたとき、第１の時間計測回路９０ｂは時間の計測を開始する。第１の時間計測回路９０ｂは、第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジを検出し、かつその立ち上がりエッジのタイミングで第２のデジタル値ＴＤＣ２１を保持する。図１１に示す例では、第１の時間計測回路９０ｂは、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジのタイミングｔｇ１２までの第２の時間Ｔ２１を計測する。第１の時間計測回路９０ｂは、第２の時間Ｔ２１を示す第２のデジタル値ＴＤＣ２１をＣＰＵ３０ｂに出力する。 When the start pulse START is output from the CPU 30b, the first time measurement circuit 90b starts measuring the time. The first time measurement circuit 90b detects the rising edge of the first measurement control signal STOP1 and holds the second digital value TDC21 at the timing of the rising edge. In the example shown in FIG. 11, the first time measurement circuit 90b measures the second time T21 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg12 of the first measurement control signal STOP1. The first time measurement circuit 90b outputs a second digital value TDC21 indicating the second time T21 to the CPU 30b.
　第１の時間計測回路９０ｂは、第１の計測制御信号ＳＴＯＰ１の立ち下がりエッジを検出し、かつその立ち下がりエッジのタイミングで第１のデジタル値ＴＤＣ１１を保持する。図１１に示す例では、第１の時間計測回路９０ｂは、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第１の計測制御信号ＳＴＯＰ１の立ち下がりエッジのタイミングｔｇ１３までの第１の時間Ｔ１１を計測する。第１の時間計測回路９０ｂは、第１の時間Ｔ１１を示す第１のデジタル値ＴＤＣ１１をＣＰＵ３０ｂに出力する。 The first time measurement circuit 90b detects the falling edge of the first measurement control signal STOP1 and holds the first digital value TDC11 at the timing of the falling edge. In the example shown in FIG. 11, the first time measurement circuit 90b measures the first time T11 from the timing tg2 of the rising edge of the start pulse START to the timing tg13 of the falling edge of the first measurement control signal STOP1. .. The first time measurement circuit 90b outputs the first digital value TDC11 indicating the first time T11 to the CPU 30b.
　タイミングｔｇ１から所定の時間Ｔｓｗが経過したタイミングｔｇ１４において、ＣＰＵ３０ｂは制御信号ＳＷを信号生成回路１１０ｂに出力する。信号生成回路１１０ｂは第１の計測制御信号ＳＴＯＰ１の出力を停止し、かつ第２の計測制御信号ＳＴＯＰ２の出力を開始する。 At the timing tg14 when the predetermined time Tsw has elapsed from the timing tg1, the CPU 30b outputs the control signal SW to the signal generation circuit 110b. The signal generation circuit 110b stops the output of the first measurement control signal STOP1 and starts the output of the second measurement control signal STOP2.
　エコー信号ＲＸａｃ２（成分ＲＸ４）の電圧が増加し、かつ第２の閾値ＴＨｎと一致したとき、信号生成回路１１０ｂは、第２の比較器８０から出力された第２の比較信号ＣＯＭＰ２に基づいて第２の計測制御信号ＳＴＯＰ２の電圧をローレベルからハイレベルに変化させる。第２の計測制御信号ＳＴＯＰ２は、第２の比較信号ＣＯＭＰ２の立ち上がりエッジと同期した立ち上がりエッジ（第４のエッジ）を持つ。エコー信号ＲＸａｃ２（成分ＲＸ４）の電圧が増加し、かつ第１の閾値ＴＨｐと一致したとき、信号生成回路１１０ｂは、第１の比較器７０から出力された第１の比較信号ＣＯＭＰ１に基づいて第２の計測制御信号ＳＴＯＰ２の電圧をハイレベルからローレベルに変化させる。第２の計測制御信号ＳＴＯＰ２は、第１の比較信号ＣＯＭＰ１の立ち上がりエッジと同期した立ち下がりエッジ（第３のエッジ）を持つ。 When the voltage of the echo signal RXac2 (component RX4) increases and matches the second threshold value THn, the signal generation circuit 110b is based on the second comparison signal COMP2 output from the second comparator 80. The voltage of the measurement control signal STOP2 of 2 is changed from a low level to a high level. The second measurement control signal STOP2 has a rising edge (fourth edge) synchronized with the rising edge of the second comparison signal COMP2. When the voltage of the echo signal RXac2 (component RX4) increases and matches the first threshold value THp, the signal generation circuit 110b is based on the first comparison signal COMP1 output from the first comparator 70. The voltage of the measurement control signal STOP2 of 2 is changed from a high level to a low level. The second measurement control signal STOP2 has a falling edge (third edge) synchronized with the rising edge of the first comparison signal COMP1.
　第２の時間計測回路１００ｂは、第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジを検出し、かつその立ち上がりエッジのタイミングで第２のデジタル値ＴＤＣ２２を保持する。図１１に示す例では、第２の時間計測回路１００ｂは、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジのタイミングｔｇ１５までの第２の時間Ｔ２２を計測する。第２の時間計測回路１００ｂは、第２の時間Ｔ２２を示す第２のデジタル値ＴＤＣ２２をＣＰＵ３０ｂに出力する。 The second time measurement circuit 100b detects the rising edge of the second measurement control signal STOP2 and holds the second digital value TDC22 at the timing of the rising edge. In the example shown in FIG. 11, the second time measurement circuit 100b measures the second time T22 from the rising edge timing tg2 of the start pulse START to the rising edge timing tg15 of the second measurement control signal STOP2. The second time measurement circuit 100b outputs a second digital value TDC22 indicating the second time T22 to the CPU 30b.
　第２の時間計測回路１００ｂは、第２の計測制御信号ＳＴＯＰ２の立ち下がりエッジを検出し、かつその立ち下がりエッジのタイミングで第１のデジタル値ＴＤＣ１２を保持する。図１１に示す例では、第２の時間計測回路１００ｂは、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第２の計測制御信号ＳＴＯＰ２の立ち下がりエッジのタイミングｔｇ１６までの第１の時間Ｔ１２を計測する。第２の時間計測回路１００ｂは、第１の時間Ｔ１２を示す第１のデジタル値ＴＤＣ１２をＣＰＵ３０ｂに出力する。 The second time measurement circuit 100b detects the falling edge of the second measurement control signal STOP2, and holds the first digital value TDC12 at the timing of the falling edge. In the example shown in FIG. 11, the second time measurement circuit 100b measures the first time T12 from the timing tg2 of the rising edge of the start pulse START to the timing tg16 of the falling edge of the second measurement control signal STOP2. .. The second time measurement circuit 100b outputs the first digital value TDC12 indicating the first time T12 to the CPU 30b.
　超音波計測装置１ｂは、Ｅｃｈｏ－ｔｏ－Ｅｃｈｏ計測を２回以上実行してもよい。例えば、第１の時間計測回路９０ｂが時間を計測した後、第２の時間計測回路１００ｂは時間を計測する。第２の時間計測回路１００ｂが時間を計測している間にＣＰＵ３０ｂは第１の時間計測回路９０ｂのメモリから第１のデジタル値ＴＤＣ１１および第２のデジタル値ＴＤＣ２１を読み出す。第１のデジタル値ＴＤＣ１１および第２のデジタル値ＴＤＣ２１が読み出された後、第１の時間計測回路９０ｂのメモリにおける第１のデジタル値ＴＤＣ１１および第２のデジタル値ＴＤＣ２１は消去される。 The ultrasonic measuring device 1b may execute the Echo-to-Echo measurement twice or more. For example, after the first time measuring circuit 90b measures the time, the second time measuring circuit 100b measures the time. While the second time measurement circuit 100b is measuring the time, the CPU 30b reads the first digital value TDC11 and the second digital value TDC21 from the memory of the first time measurement circuit 90b. After the first digital value TDC11 and the second digital value TDC21 are read out, the first digital value TDC11 and the second digital value TDC21 in the memory of the first time measurement circuit 90b are erased.
　第２の時間計測回路１００ｂが時間を計測した後、第１の時間計測回路９０ｂは時間を再度計測する。第１の時間計測回路９０ｂが時間を計測している間にＣＰＵ３０ｂは第２の時間計測回路１００ｂのメモリから第１のデジタル値ＴＤＣ１２および第２のデジタル値ＴＤＣ２２を読み出す。第１のデジタル値ＴＤＣ１２および第２のデジタル値ＴＤＣ２２が読み出された後、第２の時間計測回路１００ｂのメモリにおける第１のデジタル値ＴＤＣ１２および第２のデジタル値ＴＤＣ２２は消去される。上記の動作が繰り返される。 After the second time measurement circuit 100b measures the time, the first time measurement circuit 90b measures the time again. While the first time measuring circuit 90b is measuring the time, the CPU 30b reads the first digital value TDC12 and the second digital value TDC22 from the memory of the second time measuring circuit 100b. After the first digital value TDC12 and the second digital value TDC22 are read out, the first digital value TDC12 and the second digital value TDC22 in the memory of the second time measurement circuit 100b are erased. The above operation is repeated.
　第３の実施形態において、第１の時間計測回路９０ｂは、被検体の表面で反射した超音波信号のエコー信号ＲＸａｃ２（成分ＲＸ３）に基づいて時間を計測する。第２の時間計測回路１００ｂは、被検体の裏面で反射した超音波信号のエコー信号ＲＸａｃ２（成分ＲＸ４）に基づいて時間を計測する。そのため、超音波計測装置１ｂは、Ｅｃｈｏ－ｔｏ－Ｅｃｈｏ計測を実行することができる。 In the third embodiment, the first time measurement circuit 90b measures the time based on the echo signal RXac2 (component RX3) of the ultrasonic signal reflected on the surface of the subject. The second time measurement circuit 100b measures the time based on the echo signal RXac2 (component RX4) of the ultrasonic signal reflected on the back surface of the subject. Therefore, the ultrasonic measuring device 1b can perform Echo-to-Echo measurement.
　ＣＰＵ３０ｂは、第１の実施形態の変形例における方法と同様の方法を使用することにより第１の閾値ＴＨｐ、第２の閾値ＴＨｎ、および第２の増幅器６０のゲインを変更してもよい。ＣＰＵ３０ｂが制御信号ＳＷを出力する前に、ＣＰＵ３０ｂは、第１の期間において第１の時間計測回路９０ｂが計測した時間に基づいて第１の閾値ＴＨｐ、第２の閾値ＴＨｎ、および第２の増幅器６０のゲインを変更してもよい。 The CPU 30b may change the gains of the first threshold value THp, the second threshold value THn, and the second amplifier 60 by using the same method as the method in the modified example of the first embodiment. Before the CPU 30b outputs the control signal SW, the CPU 30b has a first threshold THp, a second threshold THn, and a second amplifier based on the time measured by the first time measurement circuit 90b in the first period. The gain of 60 may be changed.
　（第４の実施形態）
　本発明の第４の実施形態を説明する。第４の実施形態において、被検体の腐食の検査が実施される。図１２および図１３を参照し、腐食の検査の原理を説明する。 (Fourth Embodiment)
A fourth embodiment of the present invention will be described. In the fourth embodiment, a test for corrosion of the subject is performed. The principle of corrosion inspection will be described with reference to FIGS. 12 and 13.
　図１２は、腐食の検査が実施される状況の例を示す。超音波振動子１０は被検体２２０上に設置される。被検体２２０は、金属で構成されたパイプである。被検体２２０の厚さはＤである。 FIG. 12 shows an example of a situation in which a corrosion inspection is carried out. The ultrasonic vibrator 10 is installed on the subject 220. The subject 220 is a pipe made of metal. The thickness of the subject 220 is D.
　図１３は、駆動信号ＴＸおよびエコー信号ＲＸの各々の波形を示す。図１３における横方向は時間を示し、かつ図１３における縦方向は各信号の電圧を示す。 FIG. 13 shows the waveforms of the drive signal TX and the echo signal RX, respectively. The horizontal direction in FIG. 13 indicates time, and the vertical direction in FIG. 13 indicates the voltage of each signal.
　被検体２２０の厚さＤが変わらずに被検体２２０の表面の凹凸の度合いが腐食により増加する場合がある。被検体２２０が腐食していない場合、エコー信号ＲＸは成分ＲＸ５を含む。被検体２２０が腐食している場合、エコー信号ＲＸは成分ＲＸ６を含む。 The thickness D of the subject 220 does not change, and the degree of unevenness on the surface of the subject 220 may increase due to corrosion. If the subject 220 is not corroded, the echo signal RX contains component RX5. If the subject 220 is corroded, the echo signal RX contains component RX6.
　タイミングｔｇ１において駆動信号ＴＸが超音波振動子１０に出力された後、タイミングｔｇ１７においてエコー信号ＲＸのパルスが超音波振動子１０から出力される。成分ＲＸ６が超音波振動子１０から出力されるタイミングは、成分ＲＸ５が超音波振動子１０から出力されるタイミングと同じである。被検体２２０が腐食している場合と被検体２２０が腐食していない場合とのいずれにおいても、超音波信号が被検体２２０内で伝搬する時間は変化しない。しかしながら、超音波信号が反射面で拡散するため、成分ＲＸ６の振幅は成分ＲＸ５の振幅よりも小さくなる。エコー信号ＲＸの振幅の変化を検出することにより、被検体２２０の腐食の度合いを確認することができる。 After the drive signal TX is output to the ultrasonic vibrator 10 at the timing tg1, the pulse of the echo signal RX is output from the ultrasonic vibrator 10 at the timing tg17. The timing at which the component RX 6 is output from the ultrasonic vibrator 10 is the same as the timing at which the component RX 5 is output from the ultrasonic vibrator 10. The time for the ultrasonic signal to propagate in the subject 220 does not change regardless of whether the subject 220 is corroded or the subject 220 is not corroded. However, since the ultrasonic signal is diffused on the reflecting surface, the amplitude of the component RX6 is smaller than the amplitude of the component RX5. By detecting the change in the amplitude of the echo signal RX, the degree of corrosion of the subject 220 can be confirmed.
　図１４は、第４の実施形態の超音波計測装置１ｃの構成を示す。図１４に示す超音波計測装置１ｃは、超音波振動子１０、駆動回路２０、ＣＰＵ３０ｃ（時間算出回路、振幅推定回路）、パルス遮断回路４０、第１の増幅器５０、第２の増幅器６０、第１の比較器７０、第２の比較器８０、第１の時間計測回路９０、および第２の時間計測回路１００を有する。図１に示す構成と同じ構成の説明を省略する。 FIG. 14 shows the configuration of the ultrasonic measuring device 1c according to the fourth embodiment. The ultrasonic measuring device 1c shown in FIG. 14 includes an ultrasonic transducer 10, a drive circuit 20, a CPU 30c (time calculation circuit, an amplitude estimation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a second amplifier. It has a comparator 70, a second comparator 80, a first time measuring circuit 90, and a second time measuring circuit 100. The description of the same configuration as that shown in FIG. 1 will be omitted.
　ＣＰＵ３０ｃは、図１に示すＣＰＵ３０の機能を有する。また、ＣＰＵ３０ｃは、第１の時間計測回路９０によって計測された第１の時間と、第２の時間計測回路１００によって計測された第２の時間との少なくとも一方に基づいてエコー信号ＲＸａｃ２の最大振幅を推定する。 The CPU 30c has the function of the CPU 30 shown in FIG. Further, the CPU 30c has a maximum amplitude of the echo signal RXac2 based on at least one of the first time measured by the first time measurement circuit 90 and the second time measured by the second time measurement circuit 100. To estimate.
　第１の時間計測回路９０は第１のデジタル値ＴＤＣ１をＣＰＵ３０ｃに出力し、かつ第２の時間計測回路１００は第２のデジタル値ＴＤＣ２をＣＰＵ３０ｃに出力する。ＣＰＵ３０ｃは、第１のデジタル値ＴＤＣ１および第２のデジタル値ＴＤＣ２の少なくとも一方に基づいてエコー信号ＲＸａｃ２の最大振幅を推定する。ＣＰＵ３０ｃは、計測された厚さの値ＴＭＶと、推定された最大振幅の値ＡＭＶとを外部の回路に出力する。 The first time measurement circuit 90 outputs the first digital value TDC1 to the CPU 30c, and the second time measurement circuit 100 outputs the second digital value TDC2 to the CPU 30c. The CPU 30c estimates the maximum amplitude of the echo signal RXac2 based on at least one of the first digital value TDC1 and the second digital value TDC2. The CPU 30c outputs the measured thickness value TMV and the estimated maximum amplitude value AMV to an external circuit.
　図１５を参照し、エコー信号ＲＸａｃ２の最大振幅を推定する方法を説明する。図１５は、エコー信号ＲＸａｃ２の波形を示す。図１５における横軸は時間を示し、かつ図１５における縦軸はエコー信号ＲＸａｃ２の電圧を示す。 A method of estimating the maximum amplitude of the echo signal RXac2 will be described with reference to FIG. FIG. 15 shows the waveform of the echo signal RXac2. The horizontal axis in FIG. 15 indicates time, and the vertical axis in FIG. 15 indicates the voltage of the echo signal RXac2.
　エコー信号ＲＸａｃ２は、超音波振動子１０の共振周波数と同じ周波数を持つ正弦波である。時間ｔにおけるエコー信号ＲＸａｃ２の振幅Ｖ（ｔ）は以下の式（９）で簡易に表される。式（９）において、振幅Ｖ（ｔ）は、最大振幅Ａおよび超音波振動子１０の共振周波数ｆで表される。振幅Ｖ（ｔ）は、正弦曲線として表される。
　　Ｖ（ｔ）＝Ａ×ｓｉｎ（２πｆｔ）　　（９） The echo signal RXac2 is a sine wave having the same frequency as the resonance frequency of the ultrasonic vibrator 10. The amplitude V (t) of the echo signal RXac2 at time t is simply expressed by the following equation (9). In the formula (9), the amplitude V (t) is represented by the maximum amplitude A and the resonance frequency f of the ultrasonic vibrator 10. The amplitude V (t) is represented as a sinusoidal curve.
V (t) = A × sin (2πft) (9)
　図１５において、第１の時間Ｔ１、第２の時間Ｔ２、およびゼロクロス時間Ｔ０が示されている。ゼロクロス時間Ｔ０からΔｔだけ時間が経過したとき、エコー信号ＲＸａｃ２の振幅の変化ΔＶは以下の式（１０）で表される。
　　ΔＶ＝Ａ×ｓｉｎ（２πｆΔｔ）　　（１０） In FIG. 15, the first time T1, the second time T2, and the zero cross time T0 are shown. When the time elapses from the zero crossing time T0 by Δt, the change ΔV of the amplitude of the echo signal RXac2 is expressed by the following equation (10).
ΔV = A × sin (2πfΔt) (10)
　したがって、最大振幅Ａは以下の式（１１）で表される。
　　Ａ＝ΔＶ／ｓｉｎ（２πｆΔｔ）　　（１１） Therefore, the maximum amplitude A is expressed by the following equation (11).
A = ΔV / sin (2πfΔt) (11)
　時間Δｔが第１の時間Ｔ１とゼロクロス時間Ｔ０との差（Ｔ１－Ｔ０）であるとき、変化ΔＶは第１の閾値ＴＨｐと基準電圧Ｖｃｍとの差（ＴＨｐ－Ｖｃｍ）である。ＣＰＵ３０ｃは、差（Ｔ１－Ｔ０）、差（ＴＨｐ－Ｖｃｍ）、および超音波振動子１０の共振周波数ｆに基づいて最大振幅Ａ（第１の最大振幅）を推定する。具体的には、ＣＰＵ３０ｃは、第１の時間Ｔ１を示す第１のデジタル値ＴＤＣ１と、ゼロクロス時間Ｔ０を示すデジタル値との差を算出する。ＣＰＵ３０ｃは、デジタル値の差を差（Ｔ１－Ｔ０）として使用する。 When the time Δt is the difference (T1-T0) between the first time T1 and the zero cross time T0, the change ΔV is the difference (THp−Vcm) between the first threshold value THp and the reference voltage Vcm. The CPU 30c estimates the maximum amplitude A (first maximum amplitude) based on the difference (T1-T0), the difference (THp-Vcm), and the resonance frequency f of the ultrasonic transducer 10. Specifically, the CPU 30c calculates the difference between the first digital value TDC1 indicating the first time T1 and the digital value indicating the zero cross time T0. The CPU 30c uses the difference in digital values as the difference (T1-T0).
　時間Δｔが第２の時間Ｔ２とゼロクロス時間Ｔ０との差（Ｔ０－Ｔ２）であるとき、変化ΔＶは第２の閾値ＴＨｎと基準電圧Ｖｃｍとの差（Ｖｃｍ－ＴＨｎ）である。ＣＰＵ３０ｃは、差（Ｔ０－Ｔ２）、差（Ｖｃｍ－ＴＨｎ）、および超音波振動子１０の共振周波数ｆに基づいて最大振幅Ａ（第２の最大振幅）を推定してもよい。この場合、ＣＰＵ３０ｃは、第２の時間Ｔ２を示す第２のデジタル値ＴＤＣ２と、ゼロクロス時間Ｔ０を示すデジタル値との差を差（Ｔ０－Ｔ２）として使用する。 When the time Δt is the difference (T0-T2) between the second time T2 and the zero cross time T0, the change ΔV is the difference (Vcm-THn) between the second threshold value THn and the reference voltage Vcm. The CPU 30c may estimate the maximum amplitude A (second maximum amplitude) based on the difference (T0-T2), the difference (Vcm-THn), and the resonance frequency f of the ultrasonic transducer 10. In this case, the CPU 30c uses the difference between the second digital value TDC2 indicating the second time T2 and the digital value indicating the zero cross time T0 as the difference (T0-T2).
　ＣＰＵ３０ｃは、上記の第１の最大振幅および第２の最大振幅の平均を算出してもよい。ＣＰＵ３０ｃは、算出された平均を最大振幅の値ＡＭＶとして出力してもよい。 The CPU 30c may calculate the average of the first maximum amplitude and the second maximum amplitude described above. The CPU 30c may output the calculated average as the maximum amplitude value AMV.
　超音波振動子１０が超音波信号を第１のタイミングで被検体に送信したとき、ＣＰＵ３０ｃはエコー信号ＲＸａｃ２の最大振幅である第１の振幅を推定してもよい。超音波振動子１０が超音波信号を第１のタイミングよりも後の第２のタイミングで被検体に送信したとき、ＣＰＵ３０ｃはエコー信号ＲＸａｃ２の最大振幅である第２の振幅を推定してもよい。ＣＰＵ３０ｃ（腐食推定回路）は、第１の振幅および第２の振幅に基づいて被検体の腐食の程度を推定してもよい。 When the ultrasonic transducer 10 transmits the ultrasonic signal to the subject at the first timing, the CPU 30c may estimate the first amplitude, which is the maximum amplitude of the echo signal RXac2. When the ultrasonic transducer 10 transmits the ultrasonic signal to the subject at the second timing after the first timing, the CPU 30c may estimate the second amplitude, which is the maximum amplitude of the echo signal RXac2. .. The CPU 30c (corrosion estimation circuit) may estimate the degree of corrosion of the subject based on the first amplitude and the second amplitude.
　例えば、ＣＰＵ３０ｃは、第１の振幅と第２の振幅との比（第２の振幅／第１の振幅）を算出し、その比に基づいて腐食の程度を推定してもよい。例えば、ＣＰＵ３０ｃは、その比と所定の閾値（例えば、０．９）とを比較してもよい。その比が所定の閾値以上である場合、ＣＰＵ３０ｃは、被検体が腐食していないと判断してもよい。その比が所定の閾値よりも小さい場合、ＣＰＵ３０ｃは、被検体が腐食していると判断してもよい。 For example, the CPU 30c may calculate the ratio of the first amplitude to the second amplitude (second amplitude / first amplitude) and estimate the degree of corrosion based on the ratio. For example, the CPU 30c may compare the ratio with a predetermined threshold (eg, 0.9). When the ratio is equal to or higher than a predetermined threshold value, the CPU 30c may determine that the subject is not corroded. If the ratio is smaller than a predetermined threshold, the CPU 30c may determine that the subject is corroded.
　第３の実施形態において、ＣＰＵ３０ｃは、第１の時間および第２の時間の少なくとも一方に基づいてエコー信号ＲＸａｃ２の最大振幅を推定する。そのため、超音波計測装置１ｃは、ＡＤ変換を連続的に実施せずに、被検体の厚さとエコー信号ＲＸａｃ２の最大振幅とを計測することができる。 In the third embodiment, the CPU 30c estimates the maximum amplitude of the echo signal RXac2 based on at least one of the first time and the second time. Therefore, the ultrasonic measuring device 1c can measure the thickness of the subject and the maximum amplitude of the echo signal RXac2 without continuously performing the AD conversion.
　（第４の実施形態の第１の変形例）
　本発明の第４の実施形態の第１の変形例を説明する。式（１１）は正弦関数を含むため、最大振幅の計算が複雑である。第４の実施形態の第１の変形例において、ＣＰＵ３０ｃは、第１の時間および第２の時間の少なくとも一方を使用することによりエコー信号ＲＸａｃ２の振幅を示す曲線の傾きをゼロクロス点において推定する。ＣＰＵ３０ｃは、その傾きに基づいてエコー信号ＲＸａｃ２の最大振幅を推定する。 (First modification of the fourth embodiment)
A first modification of the fourth embodiment of the present invention will be described. Since the equation (11) includes a sine function, the calculation of the maximum amplitude is complicated. In the first modification of the fourth embodiment, the CPU 30c estimates the slope of the curve indicating the amplitude of the echo signal RXac2 at the zero crossing point by using at least one of the first time and the second time. The CPU 30c estimates the maximum amplitude of the echo signal RXac2 based on the inclination.
　図１６を参照し、エコー信号ＲＸａｃ２の最大振幅を推定する方法を説明する。図１６は、エコー信号ＲＸａｃ２の波形を示す。図１６における横軸は時間を示し、かつ図１６における縦軸はエコー信号ＲＸａｃ２の電圧を示す。 A method of estimating the maximum amplitude of the echo signal RXac2 will be described with reference to FIG. FIG. 16 shows the waveform of the echo signal RXac2. The horizontal axis in FIG. 16 indicates time, and the vertical axis in FIG. 16 indicates the voltage of the echo signal RXac2.
　図１６において、最大振幅Ａを持つエコー信号ＲＸａｃ２の波形と、最大振幅Ａ／２を持つエコー信号ＲＸａｃ２の波形とが示されている。直線Ｌ１は、エコー信号ＲＸａｃ２が最大振幅Ａを持つときにゼロクロス点（ゼロクロス時間Ｔ０の終了タイミング）におけるエコー信号ＲＸａｃ２の傾きを示す。直線Ｌ２は、エコー信号ＲＸａｃ２が最大振幅Ａ／２を持つときにゼロクロス点におけるエコー信号ＲＸａｃ２の傾きを示す。直線Ｌ２の傾きは直線Ｌ１の傾きよりも小さい。エコー信号ＲＸａｃ２の最大振幅が小さくなるとゼロクロス点におけるエコー信号ＲＸａｃ２の傾きは小さくなる。 In FIG. 16, the waveform of the echo signal RXac2 having the maximum amplitude A and the waveform of the echo signal RXac2 having the maximum amplitude A / 2 are shown. The straight line L1 indicates the slope of the echo signal RXac2 at the zero cross point (end timing of the zero cross time T0) when the echo signal RXac2 has the maximum amplitude A. The straight line L2 indicates the slope of the echo signal RXac2 at the zero crossing point when the echo signal RXac2 has the maximum amplitude A / 2. The slope of the straight line L2 is smaller than the slope of the straight line L1. As the maximum amplitude of the echo signal RXac2 decreases, the slope of the echo signal RXac2 at the zero cross point decreases.
　ＣＰＵ３０ｃは、以下の式（１２）に従って、ゼロクロス点におけるエコー信号ＲＸａｃ２の傾きＳｌｏｐｅ０を算出する。ＣＰＵ３０ｃは、第１の時間Ｔ１を示す第１のデジタル値ＴＤＣ１と、第２の時間Ｔ２を示す第２のデジタル値ＴＤＣ２との差を差（Ｔ１－Ｔ２）として使用する。
　　Ｓｌｏｐｅ０＝（ＴＨｐ－ＴＨｎ）／（Ｔ１－Ｔ２）　　（１２） The CPU 30c calculates the slope Slope0 of the echo signal RXac2 at the zero crossing point according to the following equation (12). The CPU 30c uses the difference between the first digital value TDC1 indicating the first time T1 and the second digital value TDC2 indicating the second time T2 as the difference (T1-T2).
Slope0 = (THp-THn) / (T1-T2) (12)
　ＣＰＵ３０ｃは、傾きＳｌｏｐｅ０を最大振幅に変換する。例えば、傾きＳｌｏｐｅ０と最大振幅との関係を示す係数が予めメモリに記憶される。ＣＰＵ３０ｃは、傾きＳｌｏｐｅ０およびその係数を使用することにより最大振幅を算出する。 The CPU 30c converts the slope Slope 0 to the maximum amplitude. For example, a coefficient indicating the relationship between the slope Slope 0 and the maximum amplitude is stored in the memory in advance. The CPU 30c calculates the maximum amplitude by using the slope Slope 0 and its coefficient.
　傾きＳｌｏｐｅ０の時系列的な変化は、最大振幅の時系列的な変化に対応する。傾きＳｌｏｐｅ０の時系列的な変化を確認することにより、最大振幅の相対的な変化を確認することができる。ＣＰＵ３０ｃは、最大振幅を算出せずに傾きＳｌｏｐｅ０を外部の回路に出力してもよい。 The time-series change of the slope Slope0 corresponds to the time-series change of the maximum amplitude. By confirming the time-series change of the slope Slope0, the relative change of the maximum amplitude can be confirmed. The CPU 30c may output the slope Slope 0 to an external circuit without calculating the maximum amplitude.
　（第４の実施形態の第２の変形例）
　本発明の第４の実施形態の第２の変形例を説明する。図１７は、第４の実施形態の第２の変形例の超音波計測装置１ｄの構成を示す。図１７に示す超音波計測装置１ｄは、超音波振動子１０、駆動回路２０、ＣＰＵ３０ｄ（時間算出回路、振幅推定回路）、パルス遮断回路４０、第１の増幅器５０、第２の増幅器６０、第１の比較器７０、第２の比較器８０、第１の時間計測回路９０ｄ、第２の時間計測回路１００ｄ、およびメモリ１２０を有する。図１に示す構成と同じ構成の説明を省略する。 (Second variant of the fourth embodiment)
A second modification of the fourth embodiment of the present invention will be described. FIG. 17 shows the configuration of the ultrasonic measuring device 1d of the second modification of the fourth embodiment. The ultrasonic measuring device 1d shown in FIG. 17 includes an ultrasonic transducer 10, a drive circuit 20, a CPU 30d (time calculation circuit, an amplitude estimation circuit), a pulse cutoff circuit 40, a first amplifier 50, a second amplifier 60, and a second amplifier. It has a comparator 70, a second comparator 80, a first time measuring circuit 90d, a second time measuring circuit 100d, and a memory 120. The description of the same configuration as that shown in FIG. 1 will be omitted.
　メモリ１２０は、第１の時間、第２の時間、第１の閾値ＴＨｐ、および第２の閾値ＴＨｎを入力データとして使用し、かつエコー信号ＲＸａｃ２の振幅を正解データとして得る機械学習を通して得られた学習モデルを記憶する。 The memory 120 was obtained through machine learning that uses the first time, the second time, the first threshold THp, and the second threshold THn as input data, and obtains the amplitude of the echo signal RXac2 as correct data. Memorize the learning model.
　ＣＰＵ３０ｄは、図１に示すＣＰＵ３０の機能を有する。また、ＣＰＵ３０ｄは、エコー信号ＲＸａｃ２の波形を推定する機能を有する。ＣＰＵ３０ｄは、メモリ１２０に記憶された学習モデルを使用することにより、第１の時間、第２の時間、第１の閾値ＴＨｐ、および第２の閾値ＴＨｎに基づいてエコー信号ＲＸａｃ２の最大振幅を推定する。ＣＰＵ３０ｄは、計測された厚さの値ＴＭＶと、推定された最大振幅の値ＡＭＶとを外部の回路に出力する。 The CPU 30d has the function of the CPU 30 shown in FIG. Further, the CPU 30d has a function of estimating the waveform of the echo signal RXac2. The CPU 30d estimates the maximum amplitude of the echo signal RXac2 based on the first time, the second time, the first threshold THp, and the second threshold THn by using the learning model stored in the memory 120. do. The CPU 30d outputs the measured thickness value TMV and the estimated maximum amplitude value AMV to an external circuit.
　第１の時間計測回路９０ｄおよび第２の時間計測回路１００ｄはＴＤＣ回路である。第１の時間計測回路９０ｄは、スタートパルスＳＴＡＲＴが示すスタートタイミングから第１の計測制御信号ＳＴＯＰ１が示す第１のタイミングまでの第１の時間を計測する。第１のタイミングは、第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジのタイミングと、第１の計測制御信号ＳＴＯＰ１の立ち下がりエッジのタイミングとを含む。したがって、第１の時間は２種類の時間を含む。 The first time measurement circuit 90d and the second time measurement circuit 100d are TDC circuits. The first time measurement circuit 90d measures the first time from the start timing indicated by the start pulse START to the first timing indicated by the first measurement control signal STOP1. The first timing includes the timing of the rising edge of the first measurement control signal STOP1 and the timing of the falling edge of the first measurement control signal STOP1. Therefore, the first time includes two kinds of time.
　具体的には、第１の時間計測回路９０ｄは、スタートタイミングから第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジのタイミングまでの時間を計測し、かつスタートタイミングから第１の計測制御信号ＳＴＯＰ１の立ち下がりエッジのタイミングまでの時間を計測する。第１の時間計測回路９０ｄは、２種類の第１の時間の各々を示す第１のデジタル値ＴＤＣ１を生成し、かつ保持する。第１の時間計測回路９０ｄは、生成された第１のデジタル値ＴＤＣ１をＣＰＵ３０ｄに出力する。 Specifically, the first time measurement circuit 90d measures the time from the start timing to the timing of the rising edge of the first measurement control signal STOP1, and from the start timing to the falling edge of the first measurement control signal STOP1. Measure the time to the timing. The first time measurement circuit 90d generates and holds a first digital value TDC1 indicating each of the two types of first time. The first time measurement circuit 90d outputs the generated first digital value TDC1 to the CPU 30d.
　第２の時間計測回路１００ｄは、スタートパルスＳＴＡＲＴが示すスタートタイミングから第２の計測制御信号ＳＴＯＰ２が示す第２のタイミングまでの第２の時間を計測する。第２のタイミングは、第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジのタイミングと、第２の計測制御信号ＳＴＯＰ２の立ち下がりエッジのタイミングとを含む。したがって、第２の時間は２種類の時間を含む。 The second time measurement circuit 100d measures the second time from the start timing indicated by the start pulse START to the second timing indicated by the second measurement control signal STOP2. The second timing includes the timing of the rising edge of the second measurement control signal STOP2 and the timing of the falling edge of the second measurement control signal STOP2. Therefore, the second time includes two kinds of time.
　具体的には、第２の時間計測回路１００ｄは、スタートタイミングから第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジのタイミングまでの時間を計測し、かつスタートタイミングから第２の計測制御信号ＳＴＯＰ２の立ち下がりエッジのタイミングまでの時間を計測する。第２の時間計測回路１００ｄは、２種類の第２の時間の各々を示す第２のデジタル値ＴＤＣ２を生成し、かつ保持する。第２の時間計測回路１００ｄは、生成された第２のデジタル値ＴＤＣ２をＣＰＵ３０ｄに出力する。 Specifically, the second time measurement circuit 100d measures the time from the start timing to the timing of the rising edge of the second measurement control signal STOP2, and from the start timing to the falling edge of the second measurement control signal STOP2. Measure the time to the timing. The second time measurement circuit 100d generates and holds a second digital value TDC2 indicating each of the two types of second time. The second time measurement circuit 100d outputs the generated second digital value TDC2 to the CPU 30d.
　図１８を参照し、学習モデルを生成するための超音波計測装置１ｄの動作を説明する。図１８は、超音波計測装置１ｄにおける各信号の波形を示す。パルスＴＸｐｒｅ、駆動信号ＴＸ、スタートパルスＳＴＡＲＴ、エコー信号ＲＸａｃ２、第１の計測制御信号ＳＴＯＰ１、および第２の計測制御信号ＳＴＯＰ２の各々の波形が図１８に示されている。図１８における横方向は時間を示し、かつ図１８における縦方向は各信号の電圧を示す。図２に示す動作と同じ動作の説明を省略する。 The operation of the ultrasonic measuring device 1d for generating the learning model will be described with reference to FIG. FIG. 18 shows the waveform of each signal in the ultrasonic measuring device 1d. The waveforms of the pulse TXpre, the drive signal TX, the start pulse START, the echo signal RXac2, the first measurement control signal STOP1, and the second measurement control signal STOP2 are shown in FIG. The horizontal direction in FIG. 18 indicates time, and the vertical direction in FIG. 18 indicates the voltage of each signal. The description of the same operation as that shown in FIG. 2 will be omitted.
　ＣＰＵ３０ｄは、タイミングｔｇ１でパルスＴＸｐｒｅを駆動回路２０に出力する。タイミングｔｇ１から所定の時間Ｔｓｔｏｆｆが経過したタイミングｔｇ２において、ＣＰＵ３０ｄはスタートパルスＳＴＡＲＴを第１の時間計測回路９０ｄおよび第２の時間計測回路１００ｄに出力する。 The CPU 30d outputs the pulse TXpre to the drive circuit 20 at the timing tg1. At the timing tg2 in which the predetermined time Tstoff has elapsed from the timing tg1, the CPU 30d outputs the start pulse START to the first time measurement circuit 90d and the second time measurement circuit 100d.
　エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐよりも小さいとき、第１の比較器７０は、ローレベルである第１の計測制御信号ＳＴＯＰ１を出力する。エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐ以上であるとき、第１の比較器７０は、ハイレベルである第１の計測制御信号ＳＴＯＰ１を出力する。 When the voltage of the echo signal RXac2 is smaller than the first threshold value THp, the first comparator 70 outputs the first measurement control signal STOP1 which is a low level. When the voltage of the echo signal RXac2 is equal to or higher than the first threshold value THp, the first comparator 70 outputs the first measurement control signal STOP1 which is a high level.
　エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎよりも小さいとき、第２の比較器８０は、ローレベルである第２の計測制御信号ＳＴＯＰ２を出力する。エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎ以上であるとき、第２の比較器８０は、ハイレベルである第２の計測制御信号ＳＴＯＰ２を出力する。 When the voltage of the echo signal RXac2 is smaller than the second threshold value THn, the second comparator 80 outputs the second measurement control signal STOP2 which is a low level. When the voltage of the echo signal RXac2 is equal to or higher than the second threshold value THn, the second comparator 80 outputs the second measurement control signal STOP2 which is a high level.
　スタートパルスＳＴＡＲＴがＣＰＵ３０ｄから出力されたとき、第１の時間計測回路９０ｄおよび第２の時間計測回路１００ｄは時間の計測を開始する。第１の時間計測回路９０ｄは、第１の計測制御信号ＳＴＯＰ１の立ち上がりエッジおよび第１の計測制御信号ＳＴＯＰ１の立ち下がりエッジの各々を検出し、かつ各エッジのタイミングで第１のデジタル値ＴＤＣ１を保持する。第２の時間計測回路１００ｄは、第２の計測制御信号ＳＴＯＰ２の立ち上がりエッジおよび第２の計測制御信号ＳＴＯＰ２の立ち下がりエッジの各々を検出し、かつ各エッジのタイミングで第２のデジタル値ＴＤＣ２を保持する。 When the start pulse START is output from the CPU 30d, the first time measurement circuit 90d and the second time measurement circuit 100d start measuring the time. The first time measurement circuit 90d detects each of the rising edge of the first measurement control signal STOP1 and the falling edge of the first measurement control signal STOP1, and sets the first digital value TDC1 at the timing of each edge. Hold. The second time measurement circuit 100d detects each of the rising edge of the second measurement control signal STOP2 and the falling edge of the second measurement control signal STOP2, and sets the second digital value TDC2 at the timing of each edge. Hold.
　図１８に示す例では、第２の時間計測回路１００ｄは、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第２の計測制御信号ＳＴＯＰ２の１回目の立ち下がりエッジのタイミングまでの第２の時間Ｔ２１を計測する。第２の時間計測回路１００ｄは、タイミングｔｇ２から第２の計測制御信号ＳＴＯＰ２の１回目の立ち上がりエッジのタイミングまでの第２の時間Ｔ２２を計測する。第２の時間計測回路１００ｄは、タイミングｔｇ２から第２の計測制御信号ＳＴＯＰ２の２回目の立ち下がりエッジのタイミングまでの第２の時間Ｔ２３を計測する。第２の時間計測回路１００ｄは、タイミングｔｇ２から第２の計測制御信号ＳＴＯＰ２の２回目の立ち上がりエッジのタイミングまでの第２の時間Ｔ２４を計測する。第２の時間計測回路１００ｄは、第２の時間Ｔ２１、第２の時間Ｔ２２、第２の時間Ｔ２３、および第２の時間Ｔ２４の各々を示す第２のデジタル値ＴＤＣ２をＣＰＵ３０ｄに出力する。 In the example shown in FIG. 18, the second time measurement circuit 100d sets the second time T21 from the timing tg2 of the rising edge of the start pulse START to the timing of the first falling edge of the second measurement control signal STOP2. measure. The second time measurement circuit 100d measures the second time T22 from the timing tg2 to the timing of the first rising edge of the second measurement control signal STOP2. The second time measurement circuit 100d measures the second time T23 from the timing tg2 to the timing of the second falling edge of the second measurement control signal STOP2. The second time measurement circuit 100d measures the second time T24 from the timing tg2 to the timing of the second rising edge of the second measurement control signal STOP2. The second time measurement circuit 100d outputs a second digital value TDC2 indicating each of the second time T21, the second time T22, the second time T23, and the second time T24 to the CPU 30d.
　第２の時間計測回路１００ｄは、第２の計測制御信号ＳＴＯＰ２の３回目の立ち下がり、第２の計測制御信号ＳＴＯＰ２の３回目の立ち上がり、第２の計測制御信号ＳＴＯＰ２の４回目の立ち下がり、および第２の計測制御信号ＳＴＯＰ２の４回目の立ち上がりにおいても第２の時間を計測する。以下では、これらのタイミングで計測された第２の時間に対応する第２のデジタル値ＴＤＣ２に関する説明を省略する。 In the second time measurement circuit 100d, the second measurement control signal STOP2 falls for the third time, the second measurement control signal STOP2 rises for the third time, and the second measurement control signal STOP2 falls for the fourth time. And the second time is also measured at the fourth rise of the second measurement control signal STOP2. Hereinafter, the description of the second digital value TDC2 corresponding to the second time measured at these timings will be omitted.
　図１８に示す例では、第１の時間計測回路９０ｄは、スタートパルスＳＴＡＲＴの立ち上がりエッジのタイミングｔｇ２から第１の計測制御信号ＳＴＯＰ１の１回目の立ち上がりエッジのタイミングまでの第１の時間Ｔ１１を計測する。第１の時間計測回路９０ｄは、タイミングｔｇ２から第１の計測制御信号ＳＴＯＰ１の１回目の立ち下がりエッジのタイミングまでの第１の時間Ｔ１２を計測する。第１の時間計測回路９０ｄは、タイミングｔｇ２から第１の計測制御信号ＳＴＯＰ１の２回目の立ち上がりエッジのタイミングまでの第１の時間Ｔ１３を計測する。第１の時間計測回路９０ｄは、タイミングｔｇ２から第１の計測制御信号ＳＴＯＰ１の２回目の立ち下がりエッジのタイミングまでの第１の時間Ｔ１４を計測する。第１の時間計測回路９０ｄは、第１の時間Ｔ１１、第１の時間Ｔ１２、第１の時間Ｔ１３、および第１の時間Ｔ１４の各々を示す第１のデジタル値ＴＤＣ１をＣＰＵ３０ｄに出力する。 In the example shown in FIG. 18, the first time measurement circuit 90d measures the first time T11 from the timing tg2 of the rising edge of the start pulse START to the timing of the first rising edge of the first measurement control signal STOP1. do. The first time measurement circuit 90d measures the first time T12 from the timing tg2 to the timing of the first falling edge of the first measurement control signal STOP1. The first time measurement circuit 90d measures the first time T13 from the timing tg2 to the timing of the second rising edge of the first measurement control signal STOP1. The first time measurement circuit 90d measures the first time T14 from the timing tg2 to the timing of the second falling edge of the first measurement control signal STOP1. The first time measurement circuit 90d outputs a first digital value TDC1 indicating each of the first time T11, the first time T12, the first time T13, and the first time T14 to the CPU 30d.
　第１の時間計測回路９０ｄは、第１の計測制御信号ＳＴＯＰ１の３回目の立ち上がりおよび第１の計測制御信号ＳＴＯＰ１の３回目の立ち下がりにおいても第１の時間を計測する。以下では、これらのタイミングで計測された第１の時間に対応する第１のデジタル値ＴＤＣ１に関する説明を省略する。 The first time measurement circuit 90d also measures the first time at the third rise of the first measurement control signal STOP1 and the third fall of the first measurement control signal STOP1. Hereinafter, the description of the first digital value TDC1 corresponding to the first time measured at these timings will be omitted.
　図１９は、各第１の時間、各第２の時間、第１の閾値ＴＨｐ、および第２の閾値ＴＨｎの関係を示す。ＣＰＵ３０ｄは、各第１の時間を示す第１のデジタル値ＴＤＣ１と、各第２の時間を示す第２のデジタル値ＴＤＣ２と、第１の閾値ＴＨｐと、第２の閾値ＴＨｎとを互いに関連付ける。また、ＣＰＵ３０ｄは、これらの値を使用し、かつディープラーニング等を使用することにより、エコー信号ＲＸａｃ２の振幅を示す曲線Ｌ３の式（正解データ）を算出する。ＣＰＵ３０ｄは、第１のデジタル値ＴＤＣ１、第２のデジタル値ＴＤＣ２、第１の閾値ＴＨｐ、第２の閾値ＴＨｎ、および曲線の式を含む学習モデルを生成する。ＣＰＵ３０ｄは、学習モデルをメモリ１２０に記憶する。 FIG. 19 shows the relationship between each first time, each second time, the first threshold THp, and the second threshold THn. The CPU 30d associates the first digital value TDC1 indicating each first time, the second digital value TDC2 indicating each second time, the first threshold value THp, and the second threshold value THn with each other. Further, the CPU 30d calculates the equation (correct answer data) of the curve L3 showing the amplitude of the echo signal RXac2 by using these values and using deep learning or the like. The CPU 30d generates a learning model including a first digital value TDC1, a second digital value TDC2, a first threshold THp, a second threshold THn, and a curve equation. The CPU 30d stores the learning model in the memory 120.
　超音波計測装置１ｄは、上記の動作を含む学習を繰り返し、かつ学習モデルを更新する。例えば、超音波計測装置１ｄは、同じ被検体に超音波信号を繰り返し送信することにより学習を繰り返す。あるいは、超音波計測装置１ｄは、１回以上の学習を実行する度に被検体を変更し、かつ学習を繰り返す。 The ultrasonic measuring device 1d repeats learning including the above operation and updates the learning model. For example, the ultrasonic measuring device 1d repeats learning by repeatedly transmitting an ultrasonic signal to the same subject. Alternatively, the ultrasonic measuring device 1d changes the subject each time the learning is executed one or more times, and repeats the learning.
　超音波計測装置１ｄの構成と同様の構成を有する外部の超音波計測装置が上記の学習を実行し、かつ学習モデルを生成してもよい。超音波計測装置１ｄは、外部の超音波計測装置と通信を実行し、かつ学習モデルを受信してもよい。 An external ultrasonic measuring device having the same configuration as that of the ultrasonic measuring device 1d may execute the above learning and generate a learning model. The ultrasonic measuring device 1d may perform communication with an external ultrasonic measuring device and receive a learning model.
　学習が終了した後、検査が実施される。図１８に示す動作と同様の動作が実行され、ＣＰＵ３０ｄは、第１のデジタル値ＴＤＣ１および第２のデジタル値ＴＤＣ２を受信する。ＣＰＵ３０ｄは、学習モデルをメモリ１２０から読み出す。ＣＰＵ３０ｄは、検査において得られた第１のデジタル値ＴＤＣ１と、検査において得られた第２のデジタル値ＴＤＣ２と、検査において使用された第１の閾値ＴＨｐと、検査において使用された第２の閾値ＴＨｎと、学習モデルとに基づいてエコー信号ＲＸａｃ２の最大振幅を推定する。 After the learning is completed, the inspection will be carried out. An operation similar to the operation shown in FIG. 18 is executed, and the CPU 30d receives the first digital value TDC1 and the second digital value TDC2. The CPU 30d reads the learning model from the memory 120. The CPU 30d has a first digital value TDC1 obtained in the test, a second digital value TDC2 obtained in the test, a first threshold value THp used in the test, and a second threshold value used in the test. The maximum amplitude of the echo signal RXac2 is estimated based on THn and the learning model.
　超音波計測装置１ｄは、２個の閾値の代わりに４個の閾値を使用してもよい。以下では、超音波計測装置１ｄが４個の比較器および４個の時間計測回路を有する例を説明する。 The ultrasonic measuring device 1d may use four threshold values instead of the two threshold values. In the following, an example in which the ultrasonic measuring device 1d has four comparators and four time measuring circuits will be described.
　４個の比較器は、第１の比較器、第２の比較器、第３の比較器、および第４の比較器を有する。第１の比較器は、エコー信号ＲＸａｃ２の電圧と基準電圧よりも正側の第１の閾値ＴＨｐ１とを比較する。エコー信号ＲＸａｃ２の電圧が第１の閾値ＴＨｐ１と一致したとき、第１の比較器は、第１のタイミングを示す第１の計測制御信号を出力する。第２の比較器は、エコー信号ＲＸａｃ２の電圧と基準電圧よりも負側の第２の閾値ＴＨｎ２とを比較する。エコー信号ＲＸａｃ２の電圧が第２の閾値ＴＨｎ２と一致したとき、第２の比較器は、第２のタイミングを示す第２の計測制御信号を出力する。 The four comparators have a first comparator, a second comparator, a third comparator, and a fourth comparator. The first comparator compares the voltage of the echo signal RXac2 with the first threshold value THp1 on the positive side of the reference voltage. When the voltage of the echo signal RXac2 matches the first threshold value THp1, the first comparator outputs the first measurement control signal indicating the first timing. The second comparator compares the voltage of the echo signal RXac2 with the second threshold THn2 on the negative side of the reference voltage. When the voltage of the echo signal RXac2 coincides with the second threshold value THn2, the second comparator outputs a second measurement control signal indicating the second timing.
　第３の比較器は、エコー信号ＲＸａｃ２の電圧と基準電圧よりも正側の第３の閾値ＴＨｐ３とを比較する。エコー信号ＲＸａｃ２の電圧が第３の閾値ＴＨｐ３と一致したとき、第３の比較器は、第３のタイミングを示す第３の計測制御信号を出力する。第４の比較器は、エコー信号ＲＸａｃ２の電圧と基準電圧よりも負側の第４の閾値ＴＨｎ４とを比較する。エコー信号ＲＸａｃ２の電圧が第４の閾値ＴＨｎ４と一致したとき、第４の比較器は、第４のタイミングを示す第４の計測制御信号を出力する。 The third comparator compares the voltage of the echo signal RXac2 with the third threshold value THp3 on the positive side of the reference voltage. When the voltage of the echo signal RXac2 matches the third threshold value THp3, the third comparator outputs a third measurement control signal indicating the third timing. The fourth comparator compares the voltage of the echo signal RXac2 with the fourth threshold THn4 on the negative side of the reference voltage. When the voltage of the echo signal RXac2 coincides with the fourth threshold value THn4, the fourth comparator outputs a fourth measurement control signal indicating the fourth timing.
　図２０は、第１の閾値ＴＨｐ１、第２の閾値ＴＨｎ２、第３の閾値ＴＨｐ３、および第４の閾値ＴＨｎ４の関係を示す。第３の閾値ＴＨｐ３は、第１の閾値ＴＨｐ１よりも小さい。第４の閾値ＴＨｎ４は、第２の閾値ＴＨｎ２よりも大きい。 FIG. 20 shows the relationship between the first threshold value THp1, the second threshold value THn2, the third threshold value THp3, and the fourth threshold value THn4. The third threshold THp3 is smaller than the first threshold THp1. The fourth threshold THn4 is larger than the second threshold THn2.
　４個の時間計測回路は、第１の時間計測回路、第２の時間計測回路、第３の時間計測回路、および第４の時間計測回路を有する。第１の時間計測回路は、スタートパルスＳＴＡＲＴが示すスタートタイミングから第１の計測制御信号が示す第１のタイミングまでの第１の時間を計測する。第２の時間計測回路は、スタートタイミングから第２の計測制御信号が示す第２のタイミングまでの第２の時間を計測する。第３の時間計測回路は、スタートタイミングから第３の計測制御信号が示す第３のタイミングまでの第３の時間を計測する。第４の時間計測回路は、スタートタイミングから第４の計測制御信号が示す第４のタイミングまでの第４の時間を計測する。 The four time measurement circuits include a first time measurement circuit, a second time measurement circuit, a third time measurement circuit, and a fourth time measurement circuit. The first time measurement circuit measures the first time from the start timing indicated by the start pulse START to the first timing indicated by the first measurement control signal. The second time measurement circuit measures the second time from the start timing to the second timing indicated by the second measurement control signal. The third time measurement circuit measures the third time from the start timing to the third timing indicated by the third measurement control signal. The fourth time measurement circuit measures the fourth time from the start timing to the fourth timing indicated by the fourth measurement control signal.
　ＣＰＵ３０ｄは、第１から第４の時間を示すデジタル値と、第１から第４の閾値とを使用する機械学習を実行することにより学習モデルを生成してもよい。ＣＰＵ３０ｄは、この学習モデルを使用することにより、エコー信号ＲＸａｃ２の振幅を高精度に推定することができる。 The CPU 30d may generate a learning model by executing machine learning using digital values indicating the first to fourth times and the first to fourth threshold values. By using this learning model, the CPU 30d can estimate the amplitude of the echo signal RXac2 with high accuracy.
　超音波計測装置１ｄは、第１の比較器７０の第１の閾値ＴＨｐおよび第２の比較器８０の第２の閾値ＴＨｎを変更し、かつ学習を繰り返してもよい。具体的には、図２０に示す第１の閾値ＴＨｐ１が第１の比較器７０に設定され、図２０に示す第２の閾値ＴＨｎ２が第２の比較器８０に設定され、かつ超音波計測装置１ｄは１回目の学習を実行する。１回目の学習において、第１の時間計測回路９０は第１の時間を計測し、かつ第２の時間計測回路１００は第２の時間を計測する。 The ultrasonic measuring device 1d may change the first threshold value THp of the first comparator 70 and the second threshold value THn of the second comparator 80, and may repeat the learning. Specifically, the first threshold value THp1 shown in FIG. 20 is set in the first comparator 70, the second threshold value THn2 shown in FIG. 20 is set in the second comparator 80, and the ultrasonic measuring device. 1d executes the first learning. In the first learning, the first time measuring circuit 90 measures the first time, and the second time measuring circuit 100 measures the second time.
　その後、図２０に示す第３の閾値ＴＨｐ３が第１の比較器７０に設定され、図２０に示す第４の閾値ＴＨｎ４が第２の比較器８０に設定され、かつ超音波計測装置１ｄは２回目の学習を実行する。２回目の学習において、第１の時間計測回路９０は第３の時間を計測し、かつ第２の時間計測回路１００は第４の時間を計測する。これにより、ＣＰＵ３０ｄは、第１から第４の時間を示すデジタル値を得ることができる。 After that, the third threshold value THp3 shown in FIG. 20 is set in the first comparator 70, the fourth threshold value THn4 shown in FIG. 20 is set in the second comparator 80, and the ultrasonic measuring device 1d is set to 2. Perform the second learning. In the second learning, the first time measuring circuit 90 measures the third time, and the second time measuring circuit 100 measures the fourth time. As a result, the CPU 30d can obtain a digital value indicating the first to fourth times.
　第４の実施形態の第２の変形例においてＣＰＵ３０ｄは、機械学習を通して得られる学習モデルを使用することによりエコー信号ＲＸａｃ２の最大振幅を推定する。そのため、超音波計測装置１ｄは、エコー信号ＲＸａｃ２の最大振幅を高精度に推定することができる。 In the second modification of the fourth embodiment, the CPU 30d estimates the maximum amplitude of the echo signal RXac2 by using a learning model obtained through machine learning. Therefore, the ultrasonic measuring device 1d can estimate the maximum amplitude of the echo signal RXac2 with high accuracy.
　以上、本発明の好ましい実施形態を説明したが、本発明はこれら実施形態およびその変形例に限定されることはない。本発明の趣旨を逸脱しない範囲で、構成の付加、省略、置換、およびその他の変更が可能である。また、本発明は前述した説明によって限定されることはなく、添付のクレームの範囲によってのみ限定される。 Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and variations thereof. Configurations can be added, omitted, replaced, and other modifications without departing from the spirit of the present invention. In addition, the present invention is not limited by the above description, but only by the scope of the appended claims.
　本発明の各実施形態によれば、超音波計測装置は、超音波信号を使用する時間計測を高精度に実行することができる。 According to each embodiment of the present invention, the ultrasonic measuring device can perform time measurement using an ultrasonic signal with high accuracy.
　１，１ａ，１ｂ，１ｃ，１ｄ，１００１　超音波計測装置
　１０，１０１０　超音波振動子
　２０，１０２０　駆動回路
　３０，３０ｂ，３０ｃ，３０ｄ，１０３０　ＣＰＵ
　４０，１０４０　パルス遮断回路
　５０，１０５０　第１の増幅器
　６０，１０６０　第２の増幅器
　７０　第１の比較器
　８０　第２の比較器
　９０，９０ｂ，９０ｄ　第１の時間計測回路
　９０ａ　時間計測回路
　１００，１００ｂ，１００ｄ　第２の時間計測回路
　１１０，１１０ｂ　信号生成回路
　１２０　メモリ
　１０７０　ＡＤＣ 1,1a, 1b, 1c, 1d, 1001 Ultrasonic measuring device 10,1010 Ultrasonic oscillator 20,1020 Drive circuit 30, 30b, 30c, 30d, 1030 CPU
40, 1040 Pulse cutoff circuit 50, 1050 First amplifier 60, 1060 Second amplifier 70 First comparator 80 Second comparator 90, 90b, 90d First time measuring circuit 90a Time measuring circuit 100, 100b , 100d Second time measurement circuit 110, 110b Signal generation circuit 120 Memory 1070 ADC

Claims (13)

  1. 　超音波信号を被検体に送信し、かつ前記超音波信号の反射信号を前記被検体から受信し、かつ前記反射信号に基づいてエコー信号を生成し、前記エコー信号は、基準電圧よりも正側の振幅と前記基準電圧よりも負側の振幅とを持つ超音波振動子と、
    　前記エコー信号の電圧と前記基準電圧よりも正側の第１の閾値とを比較し、前記エコー信号の前記電圧が前記第１の閾値と一致した第１のタイミングで第１の信号を出力する第１の比較器と、
    　前記エコー信号の電圧と前記基準電圧よりも負側の第２の閾値とを比較し、前記エコー信号の前記電圧が前記第２の閾値と一致した第２のタイミングで第２の信号を出力する第２の比較器と、
    　前記第１の信号に基づいて、前記超音波振動子が前記超音波信号を送信するタイミングと関連付けられたスタートタイミングから前記第１のタイミングまでの第１の時間を計測し、かつ前記第２の信号に基づいて前記スタートタイミングから前記第２のタイミングまでの第２の時間を計測する時間計測回路と、
    　前記第１の時間および前記第２の時間に基づいて前記スタートタイミングからゼロクロス点までの時間であるゼロクロス時間を算出し、前記ゼロクロス点は、前記エコー信号の電圧が前記第１のタイミングおよび前記第２のタイミングの間に前記基準電圧と一致したタイミングを示す時間算出回路と、
    　を有する超音波計測装置。     The ultrasonic signal is transmitted to the subject, the reflected signal of the ultrasonic signal is received from the subject, and an echo signal is generated based on the reflected signal, and the echo signal is on the positive side of the reference voltage. An ultrasonic vibrator having an amplitude of and an amplitude on the negative side of the reference voltage,
    The voltage of the echo signal is compared with the first threshold value on the positive side of the reference voltage, and the first signal is output at the first timing when the voltage of the echo signal matches the first threshold value. The first comparator and
    The voltage of the echo signal is compared with the second threshold value on the negative side of the reference voltage, and the second signal is output at the second timing when the voltage of the echo signal matches the second threshold value. The second comparator and
    Based on the first signal, the first time from the start timing associated with the timing at which the ultrasonic transducer transmits the ultrasonic signal to the first timing is measured, and the second signal A time measurement circuit that measures the second time from the start timing to the second timing based on
    The zero cross time, which is the time from the start timing to the zero cross point, is calculated based on the first time and the second time, and at the zero cross point, the voltage of the echo signal is the first timing and the second. A time calculation circuit that indicates the timing that matches the reference voltage during the timing of
    Ultrasonic measuring device with.
  2. 　前記時間計測回路は、前記第１の時間および前記第２の時間の少なくとも一方を２回以上計測し、
    　前記時間算出回路は、前記第１の時間および前記第２の時間を互いに関連付けることにより第１の組み合わせおよび第２の組み合わせを生成し、
    　前記第１の組み合わせおよび前記第２の組み合わせの各々は、前記第１の時間および前記第２の時間を含み、
    　前記第１の組み合わせの前記第１の時間は前記第２の組み合わせの前記第１の時間と異なり、または前記第１の組み合わせの前記第２の時間は前記第２の組み合わせの前記第２の時間と異なり、
    　前記時間算出回路は、前記第１の組み合わせの前記第１の時間と前記第１の組み合わせの前記第２の時間との差である第１の差を算出し、
    　前記時間算出回路は、前記第２の組み合わせの前記第１の時間と前記第２の組み合わせの前記第２の時間との差である第２の差を算出し、
    　前記第１の差の絶対値が前記第２の差の絶対値よりも小さい場合、前記時間算出回路は、前記第１の組み合わせを使用することにより前記ゼロクロス時間を算出し、
    　前記第２の差の絶対値が前記第１の差の絶対値よりも小さい場合、前記時間算出回路は、前記第２の組み合わせを使用することにより前記ゼロクロス時間を算出する
    　請求項１に記載の超音波計測装置。     The time measuring circuit measures at least one of the first time and the second time twice or more.
    The time calculation circuit generates a first combination and a second combination by associating the first time and the second time with each other.
    Each of the first combination and the second combination comprises the first time and the second time.
    The first time of the first combination is different from the first time of the second combination, or the second time of the first combination is the second time of the second combination. Unlike
    The time calculation circuit calculates the first difference, which is the difference between the first time of the first combination and the second time of the first combination.
    The time calculation circuit calculates a second difference, which is the difference between the first time of the second combination and the second time of the second combination.
    When the absolute value of the first difference is smaller than the absolute value of the second difference, the time calculation circuit calculates the zero cross time by using the first combination.
    The first aspect of claim 1, wherein when the absolute value of the second difference is smaller than the absolute value of the first difference, the time calculation circuit calculates the zero cross time by using the second combination. Ultrasonic measuring device.
  3. 　前記第１の時間と前記第２の時間との差の絶対値が所定値以内である場合、前記時間算出回路は前記ゼロクロス時間を算出する
    　請求項１に記載の超音波計測装置。     The ultrasonic measuring device according to claim 1, wherein when the absolute value of the difference between the first time and the second time is within a predetermined value, the time calculation circuit calculates the zero cross time.
  4. 　前記時間計測回路は、前記第１の時間を示す第１のデジタル値と、前記第２の時間を示す第２のデジタル値とを生成するＴＤＣ（Ｔｉｍｅ－Ｔｏ－Ｄｉｇｉｔａｌ）回路であり、
    　前記時間算出回路は、前記第１のデジタル値および前記第２のデジタル値に基づいて前記ゼロクロス時間を算出する
    　請求項１に記載の超音波計測装置。     The time measurement circuit is a TDC (Time-To-Digital) circuit that generates a first digital value indicating the first time and a second digital value indicating the second time.
    The ultrasonic measuring device according to claim 1, wherein the time calculation circuit calculates the zero cross time based on the first digital value and the second digital value.
  5. 　前記時間計測回路は、前記第１の時間および前記第２の時間の少なくとも一方を２回以上計測し、
    　前記時間計測回路は、前記第１のデジタル値および前記第２のデジタル値の少なくとも一方を２個以上生成し、
    　前記時間算出回路は、前記第１の時間および前記第２の時間の２つ以上の組み合わせから選択された前記第１の時間および前記第２の時間の組み合わせに対応する前記第１のデジタル値および前記第２のデジタル値を使用することにより前記ゼロクロス時間を算出する
    　請求項４に記載の超音波計測装置。     The time measuring circuit measures at least one of the first time and the second time twice or more.
    The time measurement circuit generates two or more of the first digital value and at least one of the second digital values.
    The time calculation circuit comprises the first digital value and the corresponding combination of the first time and the second time selected from two or more combinations of the first time and the second time. The ultrasonic measuring device according to claim 4, wherein the zero cross time is calculated by using the second digital value.
  6. 　第１の数および第２の数の少なくとも一方に基づいて前記第１の閾値を変更し、かつ前記第１の数および前記第２の数の少なくとも一方に基づいて前記第２の閾値を変更し、前記第１の数は、前記時間計測回路が前記第１の時間を計測した回数を示し、前記第２の数は、前記時間計測回路が前記第２の時間を計測した回数を示す変更回路をさらに有する
    　請求項１に記載の超音波計測装置。     Change the first threshold based on at least one of the first number and the second number, and change the second threshold based on at least one of the first number and the second number. The first number indicates the number of times the time measuring circuit measures the first time, and the second number indicates the number of times the time measuring circuit measures the second time. The ultrasonic measuring apparatus according to claim 1.
  7. 　前記エコー信号を所定のゲインで増幅する増幅器をさらに有し、
    　前記変更回路は、前記第１の数および前記第２の数の少なくとも一方に基づいて前記ゲインを変更する
    　請求項６に記載の超音波計測装置。     It further has an amplifier that amplifies the echo signal with a predetermined gain.
    The ultrasonic measuring device according to claim 6, wherein the change circuit changes the gain based on at least one of the first number and the second number.
  8. 　第１のエッジおよび第２のエッジを持つ第３の信号を生成し、前記第１のエッジは、前記第１のタイミングと同期し、前記第２のエッジは、前記第２のタイミングと同期し、前記第１のエッジおよび前記第２のエッジの一方は立ち上がりエッジであり、前記第１のエッジおよび前記第２のエッジの他方は立ち下がりエッジである信号生成回路をさらに有し、
    　前記時間計測回路は、前記第１のエッジが前記第３の信号に現れたタイミングで前記第１のデジタル値を生成し、かつ前記第２のエッジが前記第３の信号に現れたタイミングで前記第２のデジタル値を生成する
    　請求項４に記載の超音波計測装置。     A third signal with a first edge and a second edge is generated, the first edge is synchronized with the first timing, and the second edge is synchronized with the second timing. Further having a signal generation circuit in which one of the first edge and the second edge is a rising edge and the other of the first edge and the second edge is a falling edge.
    The time measurement circuit generates the first digital value at the timing when the first edge appears in the third signal, and the time measurement circuit generates the first digital value at the timing when the second edge appears in the third signal. The ultrasonic measuring device according to claim 4, which generates a second digital value.
  9. 　前記第１の時間および前記第２の時間の少なくとも一方に基づいて前記エコー信号の最大振幅を推定する振幅推定回路をさらに有する
    　請求項１に記載の超音波計測装置。     The ultrasonic measuring apparatus according to claim 1, further comprising an amplitude estimation circuit that estimates the maximum amplitude of the echo signal based on at least one of the first time and the second time.
  10. 　前記振幅推定回路は、前記第１の時間および前記第２の時間の一方と前記ゼロクロス時間との差に基づいて、かつ前記超音波振動子の共振周波数に基づいて前記最大振幅を推定する
    　請求項９に記載の超音波計測装置。     A claim that the amplitude estimation circuit estimates the maximum amplitude based on the difference between one of the first time and the second time and the zero cross time, and based on the resonance frequency of the ultrasonic vibrator. 9. The ultrasonic measuring device according to 9.
  11. 　前記第１の時間、前記第２の時間、前記第１の閾値、および前記第２の閾値を入力データとして使用し、かつ前記エコー信号の振幅を正解データとして得る機械学習を通して得られた学習モデルを記憶するメモリをさらに有し、
    　前記振幅推定回路は、前記学習モデルを使用することにより、前記第１の時間、前記第２の時間、前記第１の閾値、および前記第２の閾値に基づいて前記最大振幅を推定する
    　請求項９に記載の超音波計測装置。     A learning model obtained through machine learning that uses the first time, the second time, the first threshold, and the second threshold as input data, and obtains the amplitude of the echo signal as correct data. Has more memory to store
    Claim that the amplitude estimation circuit estimates the maximum amplitude based on the first time, the second time, the first threshold value, and the second threshold value by using the learning model. 9. The ultrasonic measuring device according to 9.
  12. 　前記超音波振動子が前記超音波信号を第１のタイミングで前記被検体に送信したとき、前記振幅推定回路は前記最大振幅である第１の振幅を推定し、
    　前記超音波振動子が前記超音波信号を前記第１のタイミングよりも後の第２のタイミングで前記被検体に送信したとき、前記振幅推定回路は前記最大振幅である第２の振幅を推定し、
    　前記超音波計測装置は、前記第１の振幅および前記第２の振幅に基づいて前記被検体の腐食の程度を推定する腐食推定回路をさらに有する
    　請求項９に記載の超音波計測装置。     When the ultrasonic vibrator transmits the ultrasonic signal to the subject at the first timing, the amplitude estimation circuit estimates the first amplitude, which is the maximum amplitude.
    When the ultrasonic vibrator transmits the ultrasonic signal to the subject at a second timing after the first timing, the amplitude estimation circuit estimates the second amplitude, which is the maximum amplitude. ,
    The ultrasonic measuring device according to claim 9, further comprising a corrosion estimation circuit that estimates the degree of corrosion of the subject based on the first amplitude and the second amplitude.
  13. 　前記振幅推定回路は、前記第１の時間および前記第２の時間の少なくとも一方を使用することにより前記エコー信号の振幅を示す曲線の傾きを前記ゼロクロス点において推定し、かつ前記傾きに基づいて前記最大振幅を推定する
    　請求項９に記載の超音波計測装置。     The amplitude estimation circuit estimates the slope of a curve indicating the amplitude of the echo signal at the zero cross point by using at least one of the first time and the second time, and the slope is based on the slope. The ultrasonic measuring device according to claim 9, wherein the maximum amplitude is estimated.
PCT/JP2020/009307 2020-03-05 2020-03-05 Ultrasonic measurement device WO2021176630A1 (en)

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Cited By (1)

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CN115355856A (en) * 2022-10-21 2022-11-18 东莞市森威电子有限公司 Ultrasonic thickness gauge

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JPS6031009A (en) * 1983-07-29 1985-02-16 Nippon Steel Corp Apparatus for measuring thickness of solidified cast piece
JPH02134511A (en) * 1988-11-15 1990-05-23 Ishikawajima Harima Heavy Ind Co Ltd Ultrasonic measurement of plate thickness
JPH02147920A (en) * 1988-11-30 1990-06-06 Yokogawa Electric Corp Measurement of sound velocity in paper
JP2000249534A (en) * 1999-03-03 2000-09-14 Hitachi Techno Eng Co Ltd Method and device for measuring coating thickness by ultrasonic wave

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Publication number Priority date Publication date Assignee Title
JPS6031009A (en) * 1983-07-29 1985-02-16 Nippon Steel Corp Apparatus for measuring thickness of solidified cast piece
JPH02134511A (en) * 1988-11-15 1990-05-23 Ishikawajima Harima Heavy Ind Co Ltd Ultrasonic measurement of plate thickness
JPH02147920A (en) * 1988-11-30 1990-06-06 Yokogawa Electric Corp Measurement of sound velocity in paper
JP2000249534A (en) * 1999-03-03 2000-09-14 Hitachi Techno Eng Co Ltd Method and device for measuring coating thickness by ultrasonic wave

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115355856A (en) * 2022-10-21 2022-11-18 东莞市森威电子有限公司 Ultrasonic thickness gauge

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