JPH0530732Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a direction-directing ultrasonic Doppler blood flow device using a non-divided transducer that can direct the direction of blood flow.

[Prior Art] Ultrasonic sensors used in ultrasonic Doppler blood flow devices that use non-divided transducers are already known, but in that case, the Doppler signals obtained from this transducer are vibrated. It is necessary to separate it from the excitation oscillation signal supplied to the child. The present applicant has already proposed a new ultrasonic Doppler blood flow device with a simplified configuration as a separation means (Utility Application No. 144130/1982).

First, an overview of such an ultrasonic Doppler blood flow device will be explained.

The ultrasonic Doppler blood flow device is intended to be applied to clinical examinations of patients by utilizing the fact that the ultrasonic frequency applied to blood vessels is shifted depending on the blood flow velocity.

Now, as shown in Fig. 4, if the ultrasonic transducer 4 is applied to the skin surface and the ultrasonic wave is irradiated to the blood vessel 11 at an angle θ, the oscillation signal for exciting the ultrasonic wave will be generated in the blood flow. It is reflected by the Doppler effect depending on the speed.

The frequency of the received signal, which is a reflected wave from the blood vessel, ie, the Doppler frequency Δ, is expressed as follows: Δ=h·cosθ·V where V is the blood flow velocity and h is a constant.

h=2 ₀ /c ₀ ; Transmission frequency c; Sound velocity If blood flow is flowing in the x direction (forward direction) as shown in the figure, the Doppler frequency received by the blood flow in the forward direction is as +Δ If the flow is in the opposite direction, it will be shifted to −Δ. The shift frequency changes depending on the blood flow velocity.

FIG. 5 shows an example of the ultrasonic sensor 10, which shows the output of the oscillator 1 (continuous wave signal, in this example
5MHz) is supplied to both ends of the non-divided type vibrator 4 via an inductance element 12 for impedance adjustment. Output terminals 13 are connected from both ends of the vibrator 4.
is derived. A resistor may be used instead of the inductance element 12.

The impedance of the inductance element 12 (its inductance is L) is determined in consideration of the impedance Zt of the vibrator 4, and its optimum condition is ωL=Zt. The natural vibration frequency of the vibrator 4 is set to the oscillation frequency of the oscillator 1.

When the oscillation output is applied to the vibrator 4, the vibrator 4 is excited, and the transmitted signal is irradiated toward the measurement target. The irradiated transmission signal receives the Doppler effect by being reflected from the moving object to be measured, so that the frequency of the received signal is modulated according to the speed of movement of the object to be measured. This becomes the Doppler frequency.

Therefore, in addition to the transmission signal, the output terminal 13 receives
A received signal subjected to the Doppler effect can be obtained at the same time. FIG. 6A shows a waveform diagram of the transmitted signal ei, and FIG. 6B shows the waveform of the output signal eo (transmitted signal ei and received signal ed).

Figure 7 shows a case in which blood flow was measured based on the Doppler signal from the ultrasonic sensor 10 described above (dots shown) and a case in which blood flow was measured using an electromagnetic flowmeter using the same experimental model. (curve y), and almost the same measured values as in the case of electromagnetic flow measurement were obtained.

Here, the inductance element 12 shown in FIG.
When a continuous wave signal (FIG. 6A) is supplied to the vibrator 4 via the oscillator 4, the vibrator 4 can be used for both wave transmission and wave reception.

If the inductance element 12 is not used, it is necessary to use the transducer for transmitting waves and the transducer for receiving waves separately.

This is because when the inductance element 12 is not connected between the oscillator 1 and the vibrator 4, the oscillator 1
This is because the output impedance on the output terminal 13 side becomes smaller than that on the output terminal 13 side, and the level of the received signal obtained at the output terminal 13 side becomes low, making it impossible to detect the received signal.

For this purpose, the impedance element 12 is interposed, and the impedances Z and Zt are selected to have the above-mentioned relationship.

Now, FIG. 8 shows an example of an ultrasonic Doppler blood flow device 20 using the ultrasonic sensor 10 described above. As the oscillator 1, an LC type or crystal resonator type oscillator can be used. 21 is a power amplifier circuit.

The output signal eo obtained at the output terminal 13 is supplied to a detection circuit 22, where a received signal subjected to the Doppler effect is detected, and the Doppler signal is subjected to a high-pass filter 23, in which signal fluctuations caused by vascular pulsations are removed. be done. The output is further supplied to a low-pass filter 24 to remove noise components contained in the Doppler signal.

Here, the cutoff frequency of the filter 23 is
80Hz, cutoff frequency of filter 24 is 7K
Approximately Hz is sufficient.

A Doppler signal (audible frequency) within a predetermined frequency band is supplied to a speaker 27 via an amplifier 25 and a power amplifier 26, and the sound of blood flowing through blood vessels is emitted as an audible sound. As a result, the blood flow condition of the subject can be diagnosed using audible sounds.

FIG. 9 shows an example of the detection circuit 22, in which transistor detection is used. Therefore, the output signal eo output to the terminal 13 is supplied to the transistor Q via the DC cut capacitor 30, and its collector output is output via the capacitor 31 to the output terminal 22a.
32 is a capacitor that determines the frequency characteristics of this detection circuit 22.

Figure 10 shows the detection characteristics of transistor Q. In this example, the static characteristics of transistor Q are used to detect the received signal that has undergone the Doppler effect by using the transmitted signal as a carrier.
ed is subjected to mixed detection.

When the ultrasonic sensor 10 is configured in this way, a received signal subjected to the Doppler effect can be separated more easily than a conventionally known ultrasonic sensor.

The 11th conventionally known ultrasonic sensor
As shown in the figure, a bridge circuit 2 is used.

In the bridge circuit 2, c and d are its output terminals, and a non-divided type resonator 4 is connected between the terminals a and c.
A capacitor 5 and an inductance element 6 are connected to each other, a resistor 7 is connected between terminals b and c, and capacitors 8 and 9 are connected between terminals a and d and between terminals b and d, respectively.

In this state, so that the output between terminals c and d becomes zero, that is, so that the bridge circuit 2 is balanced,
The constants of bridge circuit 2 are adjusted. In the example shown in FIG. 11, the inductance element 6 and the resistor 7 are each adjustable, and the balanced state of the bridge circuit 2 is adjusted by these.

When the bridge circuit 2 is balanced, no output is obtained between terminals c and d. However, the reflected wave of the ultrasonic signal transmitted from the transducer 4
is received and this reflected wave is subject to the Doppler effect, the frequency of the signal received by the same transducer 4 is different from the frequency at the time of transmission, so such a reflected signal is not received. When this occurs, the equilibrium state of the bridge circuit 2 is disrupted, and only an output (received signal) corresponding to the frequency shift due to the Doppler effect is obtained between terminals c and d.

In this way, when configuring an ultrasonic sensor using the bridge circuit 2, in order for the output obtained at terminals c and d to be only received signals subjected to the Doppler effect, it is necessary to prevent the transmitted signal ei from being output. It is necessary to precisely adjust the equilibrium state of the bridge circuit 2 using an inductance element 6 and a resistor 7.

However, as a practical matter, it is a common experience that it is quite difficult to make adjustments so that no transmission signal is obtained, and that it requires a lot of time.

Also, even if you spend a lot of time making adjustments like this, it is not possible to completely reduce the transmitted signal to zero, and the S/N
Currently, only poor output can be obtained.

Therefore, such an ultrasonic sensor has the disadvantage that the received signal subjected to the Doppler effect cannot be easily separated in a subsequent circuit system. With the configuration shown in FIG. 5, these drawbacks can be eliminated.

Now, FIG. 12 shows an example of a waveform diagram of the received signal ed. T is a waveform diagram when the blood flow is flowing in the x direction, and R is a waveform diagram when the blood flow is flowing in the opposite direction. Therefore, by observing this waveform diagram, it is possible to grasp the state of the blood vessels at the observation location, and based on this, diagnostic data for the patient can be created.

[Problems to be solved by the invention] By the way, when estimating the patient's vascular condition from the above-mentioned waveform diagram, in order to more appropriately and easily know the vascular condition, it is sufficient to listen to the sound of the blood flow. However, by simply converting the above-mentioned waveform diagram shown in FIG. 12 into an audible sound, the direction and amount of blood flow cannot be accurately grasped.

This is because blood flow sounds sound the same in both forward and reverse directions, so it is not easy to distinguish between forward and reverse directions based on blood flow sounds alone. Moreover, the level of blood flow sound in the reverse direction is lower than that in the forward direction, so there is a high possibility that the blood flow sound heard by both ears will be masked by the sound of the forward direction. This is because it is difficult to reliably determine the opposite direction.

In addition, when supplying continuous wave signals to a vibrator, the conventional configuration requires two units, one for transmitting and one for receiving, which increases costs and becomes a bottleneck in miniaturizing ultrasonic sensors. .

Therefore, in this invention, the ultrasonic sensor is miniaturized in a direction indicating type ultrasonic Doppler blood flow device that can easily determine the direction of blood flow.

[Technical means for solving the problem] In order to solve the above-mentioned problem, the direction-indicating ultrasonic Doppler blood flow device according to this invention is such that a signal from an oscillator that continuously oscillates a predetermined high-frequency signal is transmitted through an inductance element. is supplied to both ends of a non-divided type vibrator for both transmitting and receiving purposes through a predetermined phase shifted state, and the vibrator is excited, and the reflected wave of the transmitted signal from the vibrator is This received signal, which includes the transmitted signal that has undergone the Doppler effect, is supplied to first and second detectors, where the received signal is detected and a phase difference according to the direction of blood flow is detected. This configuration is configured such that the detected outputs thereof are supplied to separate sound emitting means.

[Function] According to this configuration, even if continuous waves of high-frequency signals are used, only one vibrator is required, so the configuration shown in FIG. 1 is sufficient. Therefore, the ultrasonic sensor 10 can be downsized. The signals output from the first and second detectors 42 and 62 are such that when the blood flow is in the forward direction, the signal output from the first detector 42 is the same as the signal output from the second detector 62. The phase of the signal is advanced.

Therefore, when the blood flow is flowing in the forward direction, the phase of the signal obtained from the first detector 42 is more advanced than that of the signal obtained from the second detector 62. Sound becomes audible through the first speaker or earphone 48.

Contrary to the above, when the blood flow is in the opposite direction, the signal obtained from the second detector 62 is
In this case, the blood flow sound in the opposite direction can be heard from the second speaker or earphone 68 because the phase of the signal obtained from the detector 42 is advanced.

[Embodiment] FIG. 1 is a system diagram of essential parts showing an example of a direction-indicating ultrasonic Doppler blood flow device 40 according to the invention, in which an oscillation signal (high frequency signal, continuous wave) is transmitted by a power amplifier 21, The signal is supplied via the inductance element 12 to a single vibrator 4 for transmitting and receiving waves, and this vibrator 4 is excited. The reflected wave of the transmitted signal from the vibrator 4 is received by the same vibrator 4. Vibrator 4
A second inductance element 15 is connected in parallel with this.
is connected. The purpose of the second inductance element 15 is to ensure that the received signal obtained at the output terminal 13 has a phase difference of 90° with respect to the oscillation signal.

The received signal is supplied to first and second detectors 42 and 62, and the Doppler signal contained in the received signal is detected. Here, the oscillation signal is injected into the first detector 42 as a carrier. Therefore,
As the first detector 42, an injection type mixed detector is used. On the other hand, as the second detector 62, a mixed detector as shown in FIG. 9 is used.

Due to the difference in detection processing and the relationship with the phase difference described above, the first and second detection outputs S1 and S
2 are signals that differ only in phase. Then, when the blood flow is flowing in the forward direction, the first detection output S
1 phase leads the phase of the second detection output S2, and when blood flow is flowing in the opposite direction, the phase of the second detection output S2 leads the phase of the first detection output S1. I will do it.

The first detection output S1 is transmitted through an amplifier 43, a high-pass filter 44, a low-pass filter 45, and an amplifier 46.
The blood flow sound is supplied to the speaker 48 via the power amplifier 47 and the power amplifier 47, and the blood flow sound is emitted.

Similarly, the second detection output S2 is supplied to the speaker 68 via the amplifier 63, high-pass filter 64, low-pass filter 65, amplifier 66, and power amplifier 67, respectively, and the blood flow sound is emitted.

The frequency characteristics of the filters 44, 45, 64, 65 can be selected in the same manner as in the case of FIG.

Now, when listening to the first and second detection outputs S1 and S2 through separate speakers 48 and 68, if blood flow is flowing in the forward direction, the phase of the first detection output S1 will be the second detection output. In this case, the blood flow sound is emitted from the first speaker 48 before the timing at which the blood flow sound is emitted from the second speaker 68. The timing will be faster.

Therefore, when blood flow is flowing in the forward direction, blood flow sound can be heard from the first speaker 48.

When the blood flow is flowing in the opposite direction, the phase of the second detection output S2 is ahead of the phase of the first detection output S1, so in this case, the blood flow from the first speaker 48 is The timing at which the blood flow sound is emitted from the second speaker 68 is earlier than the timing at which the sound is emitted. As a result, when blood flow is flowing in the opposite direction, blood flow sound can be heard from the second speaker 68.

In this manner, it is possible to easily and reliably distinguish between the forward direction and the reverse direction of blood flow sound based on the difference in generation timing using only audio. Blood flow sounds appear as changes in audio level, so the volume of blood flowing through blood vessels can be determined by the volume.

Note that the speaker 4 is used as a sound emitting means for the blood flow sound.
Earphones may be used instead of 8 and 68. Terminals 49 and 69 indicate its output terminals.

In the embodiment shown in FIG. 1, in addition to the function of allowing the blood flow sound to be heard as an audible sound, it is also configured so that the level display and Doppler waveform can be visually observed in a synthesized state.

The configuration and operation thereof will be explained below.

The first detection output S1, which is the output of the amplifier 46, is further supplied to a waveform shaping circuit 52 via an amplifier 51, subjected to waveform shaping, and then supplied to a phase detection circuit 53. Similarly, the second detection output S2 is supplied to the waveform shaping circuit 72 via the amplifier 71 and subjected to waveform shaping, and then supplied to the phase detection circuit 53.

Specifically, the phase detection circuit 53 detects the difference in the input timing of the first and second waveform shaping outputs,
If the input timing of the first waveform shaped output is earlier than that of the second waveform shaped output, only the first waveform shaped output is output to the corresponding output terminal 53a.

On the contrary, if the second waveform shaped output is faster than the first waveform shaped output, only the second waveform shaped output is output to the corresponding output terminal 53b.

The output obtained at the terminal 53a of the phase detection circuit 53 is supplied to the first monomulti 81 constituting the frequency/voltage converter 80 and converted into a pulse of a predetermined width. is extracted.

The output obtained at the terminal 53b is also supplied to the second monomulti 91 constituting the frequency/voltage converter 80 and converted into a pulse of a predetermined width, after which the low-frequency component is extracted by the low-pass filter 92. Therefore, the blood flow waveform is outputted to the output terminals 83 and 93 in a state where it is converted into a voltage.

Therefore, if these voltage outputs are supplied to the adder 85 and simply added, the output terminal 86 of the first
Since a blood flow waveform as shown in FIG. 2 is obtained, the blood flow waveform can be observed by supplying this output to waveform measuring means (not shown) such as an oscilloscope.

Filter 82 obtained at output terminals 83, 93,
Each output of 92 is supplied to a display, and the output level is displayed. Indicator 9 shown in FIG.
5.96 is the case where a bar-shaped indicator is used.

If such indicators 95 and 96 are arranged as shown in the figure, the direction of blood flow and the amount of blood flow can be identified without being mistaken or confused.

For example, if blood flows in the forward direction,
Outputs a and f of the amplifiers 46 and 66 have waveforms as shown in FIG. 2A and B, and by waveform shaping, outputs b and g as shown in FIG. 2C and D are obtained. Since the input timing to the phase detection circuit 53 is earlier for the first detection output S1, in this case, the input timing to the terminal 53a is earlier.
Only waveform shaping output can be obtained. This is converted into a monomulti output c (E in the same figure) with a constant pulse width, and then filtered, resulting in the low-pass output d shown in F in the same figure.The display 95 displays its level in real time. will be done.

If the blood flow is reversed, the level is displayed on the other display 96.

[Effects of the invention] As explained above, according to this invention, a signal from an oscillator that continuously oscillates a predetermined high-frequency signal is supplied to both ends of a non-split type vibrator for both transmitting and receiving waves via an inductance element. , while the above-mentioned vibrator is excited, the reflected wave of the transmitted signal from the above-mentioned vibrator is received by the same vibrator, and this received signal subjected to the Doppler effect is simultaneously transmitted to the first and second wave detectors. Since the detection outputs having different phases are heard through different speakers, the blood flow sound is emitted from different speakers when the blood flow is flowing in the forward direction and when it is flowing in the opposite direction.

Therefore, it has a feature that the direction of blood flow can be easily and reliably determined.

In addition, since the ultrasonic sensor 10 shown in FIG. 5 was used, the received signal affected by the Doppler effect can be easily separated by simply removing the transmitted signal in the subsequent circuit system. .

Furthermore, since the vibrator can be configured to be used for both transmitting and receiving waves, the ultrasonic sensor 10 can be downsized, and costs can be reduced accordingly.

For this reason, the directional ultrasonic Doppler blood flow device according to the present invention is extremely suitable for application to a diagnostic device using ultrasonic diagnosis.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an example of the essential parts of the directional ultrasonic Doppler blood flow device according to this invention;
The figure is a waveform diagram to explain its operation, Figure 3 is an illustration of a level indicator used to display blood flow, Figure 4 is an illustration of the Doppler effect, and Figure 5 is an explanation of this invention. System diagram of the ultrasonic sensor, Fig. 6 is a waveform diagram to explain its operation, Fig. 7
The figure is a measurement diagram of model experiment results for blood flow, Figure 8 is a system diagram of a blood flow device using the ultrasonic sensor of Figure 5, Figure 9 is a connection diagram showing a specific example of a detector, and Figure 10. 11 is a system diagram showing an example of an ultrasonic sensor used in a conventional blood flow device, and FIG. 12 is a diagram showing blood flow waveforms. 1... Oscillator, 4... Vibrator, 10... Ultrasonic sensor, 12, 15... Inductance element,
40...direction-indicating ultrasonic Doppler blood flow device,
42, 62...first and second detectors, 48, 6
8...Speaker, 80...Frequency/voltage converter,
eo...transmission signal, ei...reception signal.

Claims (1)

[Claims for Utility Model Registration] (1) A non-split type ultrasonic transducer and an inductance element for both transmitting and receiving waves are connected in series, and a predetermined type of ultrasonic transducer and an inductance element are connected in series. An oscillator that continuously oscillates a high frequency signal is connected, and output terminals are provided at both ends of the non-split ultrasonic transducer to simultaneously receive a continuous wave transmission signal and a continuous wave reception signal subjected to the Doppler effect. First and second detectors are provided, into which the continuous wave received signal and the continuous wave transmitted signal that have been affected are input, and which output a detected signal having a phase difference according to the blood flow direction. What is claimed is: 1. A direction-indicating ultrasonic Doppler blood flow device, characterized in that a separate sound emitting means is provided to which a detection signal having a detection signal is input. (2) The direction-indicating ultrasonic Doppler blood flow device according to claim 1, wherein a carrier injection type mixed detector is used as the first detector. (3) The direction-indicating ultrasonic Doppler blood flow device according to claim 1 or 2, in which a mixed detector is used as the second detector. (4) The direction according to claim 1, 2, or 3 of the utility model registration, in which a second inductance element is used in addition to the above-mentioned inductance element as means for shifting the transmission signal by a predetermined phase. Directed ultrasound Doppler blood flow device. (5) Claim 1 for utility model registration in which speakers or earphones are used as sound emitting means
4. The directional ultrasound Doppler blood flow device according to item 1, 2, 3, or 4. (6) Utility model registration claims 1, 2, 3, and 4 in which the first and second detection outputs are supplied to display means for displaying blood flow rate.
6. The directional ultrasound Doppler blood flow device according to item 5. (7) Utility model registration claims 1, 2, 3, and 4 in which the first and second detection outputs are combined and supplied to the waveform observation means.
6. The directional ultrasound Doppler blood flow device according to item 5 or 6.