JPH0422468B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a measuring device that measures the propagation time of an elastic wave through an object. In more detail, we can use the fact that the propagation speed of elastic waves differs depending on the type and condition of the object to investigate whether bones in living organisms are fractured or not, or to detect damage to objects buried in the ground or reinforcing bars in concrete. This invention relates to an elastic wave propagation time measurement device for investigating the state of alteration or the existence of an object.

"Prior art" When measuring the propagation time of elastic waves of a target object buried in a certain object to know the state of the buried object, for example, if the bone 2 in the living body 1 is broken? Conventionally, when investigating whether the That is, the transmitting electroacoustic transducer 3 and the receiving electroacoustic transducer 4 are installed at points A and B, which are separated by a certain distance on the surface of the living body 1 including the fracture site X. Then, an electric pulse is generated from the electric pulse oscillator 5, a counter 7 is started with the signal, a clock count from the clock signal oscillator 8 is started, and at the same time, an ultrasonic pulse is transmitted from the transmitting electroacoustic transducer 3. . This ultrasonic signal propagates through the living body 1 and bones 2
It passes through the inside of the bone 2 from point C, exits again to the living body 1 from point D, and reaches the receiving electroacoustic transducer 4 at point B. The signal received by the receiving electroacoustic transducer 4 is amplified by an amplifier 6, shaped into a waveform, and sent to a counter 7, where the counter 7 is reset. Therefore, the counter 7 measures the time from the transmitting side of the transmitting electroacoustic transducer 3 to the receiving time of the receiving electroacoustic transducer 4. Next, living organism 1
In order to eliminate the time from point A to point C and from point D to point B, the propagation constant of living body 1 and the depth to bone 2 were measured using a device different from that shown in , the arrival time of the reflected waves at points C and D is measured, the value of the counter 7 is corrected, and the value is displayed on the display 9. The displayed value is the original bone 2
If it is greater than the elastic wave propagation time of , it is determined that the bone is fractured.

"Problems to be Solved by the Invention" As described above, in the conventional method, in addition to the propagation time of the bone 2, which is the target material, there are This also includes the propagation time of living body 1 between the two, so this must be removed. Therefore, using separate devices and circuits, unnecessary propagation constants of living body 1, respective depths to bones 2, etc.
It is necessary to measure the reflection time, etc., which is a complicated operation and can lead to errors.

"Means for Solving the Problems" The present invention has been made to solve the above problems, and is applicable to an apparatus for measuring the elastic wave propagation time of a target object buried in a foreign object. , an electroacoustic transducer capable of transmitting and receiving electrical pulses is installed at two points on the surface of a foreign object near the point to be measured on the target object, and the electroacoustic transducer is A counter that measures the time of the reflected wave from the target object based on the transmitted wave and the arriving wave from another electroacoustic transducer is combined, and this counter calculates the elastic wave propagation of the target object based on the time data of each counter. It is made up of a combination of arithmetic circuits that calculate time.

"Operation" Apply an electric pulse signal to two electroacoustic transducers simultaneously, and set the time from when one electroacoustic transducer emits a signal to the arrival of the reflected signal to be 2T ₁ , and the time from the other electroacoustic transducer to the arrival of the reflected signal is 2T 1 . The time it takes for the signal to arrive is T
shall be. Similarly, the value measured by the other electroacoustic transducer is assumed to be 2T ₂ and T. Based on these data, T-2T ₁ = T ₃ and T-2T ₂ for each counter.
= T ₄ is measured. Also, if the propagation time in the target object is T ₀ , then T = T ₀ + T ₁ + T ₂ , so T ₀ = T-T ₁ - _{T 2} = 1/2 {(T-2T ₁ ) + ( T−2T ₂ )}=1/2(T ₃ +T ₄ ). Therefore, by averaging the values of the two counters using an arithmetic circuit, the propagation time of the target object can be obtained.

Note that if electric pulses are applied to the two electroacoustic transducers separately after a certain period of time and T ₃ and T ₄ are measured twice, only one counter is required.

``Example'' An example of the present invention will be described with reference to FIG. 1 and the following drawings.

2 is the target substance to be measured, and 1 is a foreign substance covering the target substance 2. Electroacoustic transducers 10 and 11 for both transmission and reception are installed at points A and B on the surface of the foreign substance 1 that are closest to the two points C and D to be measured of the target substance 2. These electroacoustic transducers 10, 11 are respectively coupled to common contacts 13, 14 of a switching circuit 12, and are connected to switching contacts 15, 14, respectively.
16 are each coupled to a measuring electric pulse oscillator 17. The other switching contacts 18 and 19 are coupled to an arithmetic circuit 24 via amplifiers 20 and 21 and counters 22 and 23, respectively, and this arithmetic circuit 24 is further coupled to a display 25. The counters 22 and 23 also include a clock signal oscillator 2.
6 are combined. The arithmetic circuit 24 is composed of an adder 27 and a divider 28.

Next, the operation of the device according to the present invention will be explained. First, the interlocking movable pieces 29 and 30 of the switching circuit 12 are connected to one of the switching contacts 15 and 16, and the electric pulses from the electric pulse oscillator 17 are transmitted to the electroacoustic transducer 1.
0 and 11 at the same time. Immediately after the application is completed, the other contacts 18 and 19 are connected. Then, elastic pulse waves are simultaneously emitted from the electroacoustic transducers 10 and 11 toward the target substance 2 at time t ₀ in FIG. 2. First, considering only one electroacoustic transducer 10, it reaches point C of the target substance 2, and this C
A part of the wave is reflected at point C, and the reflected wave at point C is received by the electro-acoustic transducer 10, which generates an electric pulse at time _t2 in FIG. The other part of the elastic pulse wave propagates inside the target material 2 at point C. The pulse wave propagated inside passes through point D and is received by the other electroacoustic transducer 11 at time _t3 in FIG. Similarly, in the other electroacoustic transducer 11, the pulse wave emitted at time _t0 is reflected at point D, and the reflected wave is received at time _t1 , and the pulse wave arriving from one electroacoustic transducer 10 is received at point D. t Receive at ₃ o'clock. The received signal is
The amplifier 2 passes through the contacts 18 and 19 of the switching circuit 12.
0 and 21, waveform shaped, and sent to counters 22 and 23, respectively. counter 2
At 2 and 23, a clock signal is input from the clock signal oscillator 26, and the clock signals corresponding to the times from _t3 to _t4 and from _t2 to _t4 are counted. This counted clock signal is sent to an adder 27 and a 2-divider 28 of the arithmetic circuit 24.

Here, the time required for the elastic wave to propagate from point A to point C is T ₁ , from point B to point D is T ₂ , and
Let T ₀ be the propagation time inside the target substance 2. Also,
The propagation time from one side 10 to the other side 11 and vice versa
The propagation time from 1 to 10 on the other hand is the same time T. T is expressed by the following formula.

T=T ₁ +T ₀ +T ₂ Also, the time interval between the reflected wave obtained by one electroacoustic transducer 10 and the arriving wave from the other is T ₃ , and similarly the time interval at the other electroacoustic transducer 11 is
If T ₄ , then T ₃ =T-2T ₁ =-T ₁ +T ₀ +T ₂ T ₄ =T-2T ₂ =T ₁ +T ₀ -T ₂ . If this is added by the adder 27, further divided into two by the 2-divider 28, and the average of both is taken, T ₃ +T ₄ /2=T ₀ is obtained, and the propagation time T ₀ of the target substance 2 is obtained.
This propagation time T ₀ is displayed on the display 25.

FIG. 3 shows another embodiment of the invention. In FIG. 3, the same parts as in FIG. 1 are given the same reference numerals.

In the embodiment shown in FIG. 1, one transmission pulse is sent to the two electroacoustic transducers 10 and 11 at the same time to complete one measurement. In contrast, in FIG. 3, one measurement is completed by alternately supplying two transmission pulses to the electroacoustic transducers 10 and 11 after a certain period of time. That is, both movable pieces 29 and 30 of the switching circuit 12 are always connected to the other contacts 18 and 19. When applying the first pulse, only one movable piece 29 is connected to one contact 1.
5 side to switch the pulse to one electroacoustic transducer 1
Apply only to 0, and when the application ends, the other contact 1
Return to 8. The reflected wave at point C is received by one electroacoustic transducer 10 and input to the amplifier 31. The pulses that subsequently pass through the target substance 2 and are received by the other electroacoustic transducer 11 are also input to the amplifier 31 . The counter 32 starts counting with the first pulse from the amplifier 31 and stops counting with the second pulse. At this time, the counter 32 holds the counted value without resetting it. next second
The transmission pulse is sent to the other movable piece 30 of the switching circuit 12.
is connected to one contact 16 side and applied to the electroacoustic transducer 11, and when the application is finished, the other contact 1
Return to 9. The signals of the reflected wave from point D received by the other electroacoustic transducer 11 and the passing wave received by one electroacoustic transducer 10 pass through the amplifier 31 to start and stop the counter 32 again. Here, the counter 32 counts the sum of the previous count value and the subsequent count value, and this value is divided into two by the 2-divider 28 and the measurement time is displayed on the display 25.

Although the embodiment shown in FIG. 3 requires at least twice the measurement time as the embodiment shown in FIG. 1, the equipment configuration is simple and economical.

In the above description, the electroacoustic transducers 10 and 11
is a transmitter/receiver type, but it is possible to use separate conversion elements for transmitter and receiver and install them close together, or to place them close together in one housing, so that the transmitter/receiver type can be used practically in the same place. Acoustic transducers can be used.

"Effects of the Invention" Since the present invention is configured as described above, the propagation time of elastic waves in different materials is measured from one side and the other for the same material, the same place, and the same time. The desired time can be obtained by removing unnecessary data. Therefore, there is an advantage that not only the measurement accuracy can be improved but also the measurement operation is simple.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the elastic wave propagation time measuring device according to the present invention, FIG. 2 is an output waveform diagram, FIG. 3 is a block diagram of another embodiment of the present invention, and FIG. It is a conventional block diagram. 1...Different substance, 2...Target substance, 3,
4,10,11...electroacoustic transducer, 5,17...
...Electric pulse oscillator, 6, 20, 21, 31...
Amplifier, 7, 22, 23, 32... counter,
8, 26... Clock signal oscillator, 9, 25...
Indicator, 12...Switching circuit, 13, 14...Common contact, 15, 16, 18, 19...Switching contact, 2
9,30...Movable piece.

Claims (1)

[Scope of Claims] 1. In an apparatus for measuring the elastic wave propagation time of a target object buried in a foreign object, two points on the surface of the foreign object near the point to be measured on the target object,
An electroacoustic transducer capable of transmitting and receiving electric pulses is installed, and each electroacoustic transducer receives reflected waves from the target object based on its own transmitted waves and waves from other electroacoustic transducers. An elastic wave propagation time characterized by combining a counter that measures the time of an arrival wave, and combining this counter with an arithmetic circuit that calculates the elastic wave propagation time of a target object from the time data of each counter. measuring device. 2. The elastic wave propagation time measuring device according to claim 1, wherein the counter is coupled to each electroacoustic transducer one by one in order to count data from the two electroacoustic transducers simultaneously. 3. The elasticity according to claim 1, wherein only one counter is coupled to two electroacoustic transducers, and the data of the two electroacoustic transducers are counted alternately at a certain time interval. Wave propagation time measuring device.