JP3386851B2 - Continuous wave Doppler ultrasound system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous wave Doppler ultrasonic diagnostic apparatus for medical use, and more particularly to a continuous wave Doppler ultrasonic diagnostic apparatus whose scanning line direction is variable (steerable).

[0002]

2. Description of the Related Art FIG. 11 is an explanatory view of the prior art. In FIG. 11, 1 is an ultrasonic diagnostic apparatus main body, 2 is an ultrasonic probe,
3 is a transmission signal line, 4 is a reception signal line, 5 is a common ground line, 6
Is a probe cable, 7 is a transmitting circuit, 8 is a receiving circuit, 10
Is a transmitting oscillator, 11 is a receiving oscillator, Zt is a series impedance of a transmission signal line, Zr is a series impedance of a reception signal line, Zc is a common impedance of a common ground line, and Zo is
Indicates the impedance of the transmitting oscillator.

In the following description, "continuous wave Doppler ultrasonic diagnostic apparatus main body" is referred to as "ultrasound diagnostic apparatus main body", "transmission side ultrasonic transducer" is referred to as "transmission transducer", and "reception side vibration". The “child” will be described as a “reception oscillator”.

§1: Description of configuration of ultrasonic diagnostic apparatus ...
See FIG. 11 (A). Conventionally, a continuous wave Doppler ultrasonic diagnostic apparatus has been known as an ultrasonic diagnostic apparatus for medical use. As shown in FIG. 11A, this continuous wave Doppler ultrasonic diagnostic apparatus includes an ultrasonic diagnostic apparatus main body 1, an ultrasonic probe 2, and the like.

A probe cable 6 (transmission line) composed of a transmission signal line 3, a reception signal line 4, a common ground line 5 and the like is provided between the ultrasonic diagnostic apparatus body 1 and the ultrasonic probe 2. It is configured to be used by connecting to a connector.

Further, the ultrasonic diagnostic apparatus main body 1 is provided with a transmitting circuit 7, a receiving circuit 8 and the like, and the ultrasonic probe 2 is provided with a transmitting oscillator (ultrasonic oscillator on the transmitting side) 10. An ultrasonic transducer including a reception transducer (reception-side ultrasonic transducer) 11 is provided.

In this case, in the ultrasonic probe 2 of the continuous wave Doppler ultrasonic diagnostic apparatus, generally, the transmission transducer 10 dedicated to transmission is used.
Then, the reception transducers 11 dedicated to reception are arranged close to each other, and transmission and reception of ultrasonic waves are continuously performed.

In the conventional transmission drive system for ultrasonic transducers,
One terminal of the two terminals of the transmitter vibrator 10 is connected to the ground potential, and electric energy is applied to the other terminal by an unbalanced driving method and an unbalanced transmission method.

The receiving oscillator 11 is also a system in which one terminal is connected to the ground potential and the received signal is received from the other terminal by an unbalanced transmission system. In particular, the electronic sector scanning ultrasonic probe, which is currently the mainstream, is manufactured to have a structure in which many ultrasonic transducers are integrated. Therefore, one of the two terminals of each ultrasonic transducer is made common and connected to the ground potential.

Therefore, as the probe cable 6, at least the transmission signal lines 3 corresponding to the number of transmission elements, the reception signal lines 4 corresponding to the reception elements, and the common ground line 5 are used. In this example, the series impedance of the transmission signal line 3 is Zt, the series impedance of the reception signal line 4 is Zr, and the common impedance of the common ground line 5 is Zc.

§2: Explanation of use of ultrasonic diagnostic equipment
-See FIG. 11B. As described above, in the structure of the probe cable 6 using an unbalanced transmission method for both transmission and reception, when the ultrasonic diagnostic apparatus is used, the transmission signal line 3 is guided to the reception signal line 4. The transmission output component is induced by the static coupling.

On the other hand, the transmission signal line 3 having a finite length,
The reception signal line 4 and the common ground line 5 have a resistance component and an inductance component which are determined by their materials and physical conditions.

Therefore, the transmission signal line 3, the reception signal line 4, and the common ground line 5 are equivalently inserted with the components (resistance component and inductance component) in series.

Therefore, the transmission signal line 3 has a series impedance Zt, and the reception signal line 4 has a series impedance Zt.
There is a common impedance Zc in r and the common ground line 5. A voltage drop as shown in FIG. 11B is caused in each of the series impedances due to the current flowing therethrough.

In the example shown in FIG. 11B, a voltage drop of (Zt × It) occurs due to the series impedance (Zt) contained in the transmission signal line 3 and the current (It) flowing therethrough.

In this case, the received signal causes the current flowing through the received signal line 4 to be sufficiently small, and the effect of its contribution is negligible and is omitted (in the following description, the effect of the received signal also affects the current). Is ignored).

Here, an electrically common conductor is used for the ground side of the transmission system and the ground side of the reception system. Therefore, the resistance component and the inductance component included in this conductor wire work as a common impedance (Zc).

The return path of the current (It) flowing from the transmission circuit 7 to the transmission oscillator 10 via the transmission signal line 3 is a common ground line 5 common to transmission and reception, in which a large current due to the transmission signal flows and potential A large voltage drop (It × Zc) occurs in the existing common impedance (Zc).

Therefore, between the grounding point of the ultrasonic diagnostic apparatus body 1 side (of the receiving circuit) and the grounding point of the receiving transducer 11,
A potential difference (It × Zc) having the same waveform as the transmission current is generated. Strictly speaking, the common impedance (Zc) must be considered as a complex impedance, and a phase difference occurs between current and voltage.

Therefore, the original ultrasonic wave reception signal (reception transducer 1) is input to the input of the receiving circuit 8 on the ultrasonic diagnostic apparatus body 1 side.
1 is a voltage (Er) induced by receiving reflected ultrasonic waves and a voltage (Er + ItxZ) obtained by adding a voltage drop (ItxZc) caused by a transmission signal generated in the common impedance.
c) is added.

In any case, the phases of the transmission signals applied to the plurality of transmission oscillators differ depending on the scanning line direction and the transmission focal position, and the leakage signal induced in each reception signal line and The voltage drop at the common impedance is the vector sum of the effects from multiple transmitted signals.

When the transmission direction is close to the direction perpendicular to the array plane of the plurality of transmission oscillators, the phases of many transmission signals become equal, so that the effects of the plurality of transmission signals are added,
The value of the voltage applied to the receiving circuit 8 becomes large.

When the periphery of the ultrasonic probe 2 and the transmission / reception circuit system are configured without taking into consideration the reduction of the leakage (crosstalk) of the transmission signal component to the reception side due to the coupling between the transmission and reception, The ratio of the crosstalk component generated by various causes to the reception voltage generated in the reception transducer 11 by the ultrasonic wave reflected by the reflector in the body that is originally required is
It can reach 100 times or more.

[0024]

SUMMARY OF THE INVENTION The above-mentioned conventional devices have the following problems. That is, when the crosstalk between the transmission and reception inside the ultrasonic probe and the probe cable or between the probe cable and the connection connector of the ultrasonic diagnostic apparatus main body is large, the maximum allowable voltage of the reception system of the ultrasonic signal ( If the maximum voltage that can be processed without distortion) is not large enough, the crosstalk component with large amplitude saturates inside the receiving circuit.

Therefore, the received signal (the originally required received signal with a small amplitude from the reflector) superimposed on the crosstalk component with a large amplitude is remarkably reduced, and the device has reduced sensitivity and dynamic range. It causes a problem of performance deterioration such as lack of performance.

The present invention solves such a conventional problem and improves the performance of a continuous wave Doppler ultrasonic diagnostic apparatus that simultaneously performs transmission and reception by reducing crosstalk from a transmission system to a reception system. The purpose is to let.

[0027]

FIG. 1 is a diagram for explaining the principle of the present invention. In FIG. 1, the same parts as those in FIG. 11 are designated by the same reference numerals. Further, reference numerals 15 and 16 denote transmitting electrodes, and 17 and 18 denote receiving electrodes.

[0028]

[0029]

[0030]

[0031]

[0032] : Transmission circuit for transmitting / receiving signals
7, and an ultrasonic diagnostic apparatus main body 1 having a receiving circuit 8,
Ultrasonic probe having transmitting oscillator 10 and receiving oscillator 11
The tentacle 2, the ultrasonic diagnostic apparatus body 1, and the ultrasonic probe
A transmission line (transmission signal line) for transmitting a signal between the slaves 2.
3, a reception signal line 4) and a pair for the transmission oscillator 10.
Then, from the transmitter circuit 7, a single frequency AC electrical energy
Is continuously applied to radiate elastic wave energy,
The reflected elastic wave energy from the reflector is
When received by the sound wave transducer 11 and converted into an electric signal
In the ultrasonic diagnostic apparatus main body 1, both of the converted electrical signals are
Wave Doppler ultrasound diagnostics to process the information contained in the signal
In the device, one of the transmission power sources constituting the transmission oscillator 10 is
Reception of one of the pole and the ultrasonic transducer 11 on the receiving side
The electrode is grounded, and the secondary side is connected to the transmitter circuit 7.
Output side has a transformer that is electrically isolated from ground potential
Continuous wave Doppler ultra equipped with balanced output power amplifier circuit
Sound wave diagnostic equipment.

[0033] :Constitution At the transmission circuit 7,
To transmit the electric energy to the transmitting oscillator 10.
Continuous wave doppling using a pair line for the transmission line (transmission signal line 3)
LA ultrasonic diagnostic equipment.

[0034] :Constitution At the transmission circuit 7,
Transmitted electric energy to the ultrasonic transducer 10 on the transmitting side
The transmission line for
Plastic ultrasonic diagnostic equipment.

[0035] :Constitution ~ Continuous wave described in any of
Balanced output power amplification in Doppler ultrasonic diagnostic equipment
Applied to the transmitter oscillator 10 as a transformer that configures the circuit
Of a narrow band whose center frequency is the fundamental wave of the AC voltage
Transmission by using a transformer with pass characteristics
The high frequency component is generated from the AC electric energy generated by the circuit 7.
The voltage waveform that is removed and supplied to the transmission oscillator 10 is distorted.
Continuous wave mode designed to be a basic wave (sine wave)
Plastic ultrasonic diagnostic equipment.

[0036] :Constitution ~ Continuous wave described in any of
Balanced output power amplification in Doppler ultrasonic diagnostic equipment
Impedance conversion function for the transformer that configures the circuit
Continuous wave Doppler ultrasonic diagnostic equipment with a built-in.

[0037]

The operation of the present invention based on the above configuration will be described with reference to FIG. When the continuous wave Doppler ultrasonic diagnostic apparatus is used, alternating-current electrical energy of a single frequency is generated from the transmission circuit 7 of the ultrasonic diagnostic apparatus main body 1 and continuously transmitted through the transmission signal line 3 to the ultrasonic probe 2. It is supplied to the transmission oscillator 10.

As a result, the transmitting oscillator 10 converts the electric energy into elastic wave energy and radiates it into the living body. On the other hand, the elastic wave energy reflected from living tissue is
The signal is received by the reception transducer 11 and converted into an electric signal. Then, this electric signal is transmitted via the reception signal line 4 to the reception circuit 8
Then, the information contained in the electric signal is processed inside the ultrasonic diagnostic apparatus main body 1. Then, the motion state of the reflector is visualized and displayed using the Doppler effect.

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

In such a continuous wave Doppler ultrasonic diagnostic apparatus
Oite, the arrangement for the transmission transducer 10 having one transmitting electrode is grounded, using a transformer on the output side of the transmission circuit, an example in which floating two-terminal side for supplying transmission power.

Since the path through which the transmission current flows is closed,
The current flowing out of the transformer on the output side of the transmission circuit and flowing into the transmission oscillator through one of the two transmission signal lines returns to the transformer of the transmission circuit through the other transmission signal line.

Therefore, currents having the same magnitude but opposite directions flow in the two transmission signal lines. In this example, the effect of the magnetic field produced by the current is canceled out. In addition, since there is no ground point other than the ground side of the transmission oscillator, no current flows between the ground points of the transmission side and the reception side.

Furthermore, since the transmission line of the transmission signal is completely separated from the reception side, the transmission current does not flow into the ground line on the reception side. Therefore, since the common impedance is not generated, the adverse effect of the voltage drop due to this is not generated.

The above configuration Then, the voltage generated by the transmission circuit 7
Transmission line for transmitting air energy to ultrasonic transducer
Uses a pair of lines for the road. in this caseTwoOn the transmission line of the book
The effect of the magnetic field generated by the flowing current is canceled out.Ru,
Since one conductor is grounded, the voltage on both conductors
Is not symmetrical with respect to ground potential.

The above configuration Is the configuration In the transmission circuit
The electric energy generated by the
And the transmission line for transmitting to the receiving transducer).
It uses a transmission line.

[0055] In this case, the magnetic field generated by the current flowing through the core wire and the outer conductor Ru offset.

Further, the configuration Compared with the coaxial transmission line
Due to the shielding effect that it has, the transmission voltage applied to the core wire is coaxial
The influence (electric field) exerted on the outside of the transmission line is reduced. Previous
Composition For continuous wave ultrasound, narrow the frequency band
Since it may be eliminated, the transmitted wave is passed through a narrow band transformer.
Removes high frequency components from the shape and eliminates unwanted
Radiation of frequency components can be suppressed.

The above configuration About the transformer
The transmitter oscillator and the power amplifier circuit for transmission.
The efficiency of the power amplifier circuit is improved by taking the impedance matching.
Can be made.

As described above, crosstalk between transmission / reception is reduced, unnecessary large-amplitude transmission signals included in signals input from the ultrasonic probe to the reception system are reduced, and amplification of the reception system is performed. Receiving performance can be improved by reducing factors that degrade performance such as circuit saturation.

[0059]

Embodiments of the present invention will be described below with reference to the drawings. 2 to 10 are views showing each embodiment of the present invention. In FIGS. 2 to 10, the same parts as those in FIGS. 1 and 10 are designated by the same reference numerals.

Further, 7A is a balanced output transmission circuit, 13 is a support, 19 is a power amplifier, 21 is a phase division circuit, 22 is a transformer, 23 is a ground wire, and 24 is a common ground electrode.
Each of the embodiments described below is an embodiment relating to the continuous wave Doppler ultrasonic diagnostic apparatus. In the following explanation,
"Continuous wave Doppler ultrasonic diagnostic device body" is "ultrasonic diagnostic device", "transmission side ultrasonic transducer" is "transmission transducer",
The “reception side transducer” will be described as a “reception transducer”.

(Explanation of First Embodiment)-See FIG. 2 FIG. 2 is an explanatory view of the first embodiment. The first embodiment will be described below with reference to FIG.

§1: Basic description of the first embodiment In general, in order to reduce the coupling between two adjacent transmission lines, a method is known in which at least one of them is a balanced transmission line.

Therefore, in the first embodiment, two transmitting electrodes of the transmitting oscillator (ultrasonic oscillator on the transmitting side) are electrically floated together (without being grounded), and a power amplifier of a balanced output type is used. The voltage is differentially applied to the two transmitting electrodes.

When the AC component is considered (the same applies hereinafter), signals having the same amplitude and opposite phases are output to the two output terminals of the balanced output type power amplifier. Two transmission signal lines from the balanced output type power amplifier to the transmission oscillator
A voltage having the same amplitude and the opposite phase with respect to the ground potential is applied.

The current flowing from the transmission signal line connected to one terminal of the transmission oscillator into the transmission oscillator flows out from the other terminal of the transmission oscillator and flows through the other transmission signal line.

That is, currents having the same amplitude but opposite directions are flowing through the two transmission signal lines. for that reason,
If the two transmission signal lines are placed close enough,
The influence (electric field) of the voltage applied to the two transmission signal lines on the surroundings cancels each other out.

Further, since the influences (magnetic fields) exerted on the surroundings by the currents flowing through the two transmission signal lines cancel each other, the influence of the reception signal on the transmission signal lines is reduced. As described above, a transmission method that has a structure in which the potentials (at least the AC component) and currents of two adjacent conducting wires are symmetrical and the two conducting wires have a mechanically equal structure is called “balanced transmission”.

Furthermore, in this system, the two conductors of the transmission system and the two conductors of the reception system (reception signal line and ground line) are completely independent, and the current flowing through the transmission oscillator is There is no common part (common impedance) in the current flowing in the receiving circuit due to the signal voltage generated in the receiving oscillator.

Therefore, the potential difference generated in the common impedance does not cause coupling between the transmission system and the reception system (see the conventional example). §2: Description by specific example In this example, the ultrasonic diagnostic apparatus main body 1 and the ultrasonic probe 2 are used.
And a probe cable (a signal transmission line composed of the transmission signal line 3 and the reception signal line 4) and the like constitute a continuous wave Doppler ultrasonic diagnostic apparatus, and the ultrasonic diagnostic apparatus main body 1 has a balanced output transmission circuit (balanced An output type transmission circuit) 7A and a reception circuit 8 are provided.

As shown in the figure, the ultrasonic probe 2 is composed of a transmitting oscillator 10 and a receiving oscillator 11. The transmission oscillator 10 includes two transmission electrodes 15 on both sides of the piezoelectric substance 14,
16 is attached and mechanically fixed by the support 13.
Further, the two transmitting electrodes 15 and 16 of the transmitting oscillator 10 are
It is electrically isolated from ground potential.

Similarly, the receiving oscillator 11 is provided with two receiving electrodes 17 and 18 on both sides of the piezoelectric substance 14 to support the support 1.
It is mechanically fixed at 3. For both ultrasonic transducers (transmitting transducer 10 and receiving transducer 11), the support 13
An acoustic lens (not shown) is attached on the side opposite to the transmission direction or the reception direction.

In the first embodiment, in particular, the transmitting electrodes 15, 1
6 and the receiving electrodes 17 and 18 are electrically insulated. Generally, in a receiving system that handles a weaker signal than a transmitting system, in order to increase resistance to external noise,
A shield structure is used.

Therefore, one of the two reception signal lines 4 connected to the two reception electrodes 17 and 18 of the reception oscillator 11 is
Connected to ground potential. In addition, the transmission electrodes 15 and 16,
Since the reception electrodes 17 and 18 are insulated, a potential can be applied to the transmission signal line 3 connected to the transmission electrode independently of the reception side, and in the configuration of FIG. It is connected to the amplifier 19 and supplied with transmission power.

The advantages of driving by the balanced output type power amplifier 19 and separating (insulating) the transmission signal line 3 and the reception signal line 4 are as described above. When using,
The balanced output transmission circuit 7A outputs a signal whose amplitude is equal to that of the ground potential and whose polarity is opposite.

The two transmission signal lines 3 have the same amplitude,
Since currents flowing in opposite directions flow, the inductions to the reception signal line 4 cancel each other. Further, both of the two transmission signal lines 3 are completely independent of the reception signal line 4, so that the transmission current does not flow through the reception signal line, and the crosstalk from the transmission side to the reception side is very high. It will be small.

There are various possible configurations of the balanced output type power amplifier, but the one shown in FIG. 2 is composed of two power amplifiers (not of the balanced type) 19 having the same characteristics and a phase division circuit 21. .

The two outputs of the phase division circuit 21 output signals of opposite phases to each other.
The signal is input to 9 and the two power amplifiers 19 obtain signals for anti-phase transmission drive.

(Explanation of the Second Embodiment) ... Refer to FIG. 3 FIG. 3 is an explanatory view of the second embodiment of the present invention. The second embodiment will be described below with reference to FIG.

§1: Basic description of the second embodiment In the second embodiment, the transmission means on the transmission side in the first embodiment is balanced transmission, and a balanced transmission line is used as the transmission line therefor. Here is an example.

Here, as described in the first embodiment, the "balanced transmission line" is a physical line for the purpose of adding a balanced signal to two conductors to reduce the influence on the surroundings from both conductors. , Two electrically equal conducting wires are arranged close to each other. A paired wire or a two-core shielded wire is often used as the balanced transmission line.

§2: Explanation by Specific Example Ultrasonic probe 2 shown in FIG. 3 and ultrasonic diagnostic apparatus main body 1
The balanced output transmission circuit 7A has the same configuration as in FIG. The second embodiment is an example in which the two transmission signal lines 3 in the configuration of FIG. 2 are balanced transmission lines.

The AC components of the potentials of the two transmission signal lines have the same amplitude and the opposite phase, and the currents flowing therethrough have the opposite directions. Further, since the two conductors are close to each other, the respective conductors The electric potential of the electric field and the influence of the current flowing therethrough on the surroundings are reduced.

(Explanation of Third Embodiment)-See FIG. 4 FIG. 4 is a view showing a third embodiment of the present invention. Less than,
A third embodiment will be described based on FIG.

§1: Basic Description of Third Embodiment The third embodiment is an example in which a coaxial transmission line is used as the transmission signal line. The coaxial transmission line is one core wire (center conductor)
And a cylindrical outer conductor that surrounds it and is electrically insulated from the core wire.

When a signal voltage is applied between the outer conductor and the core wire, the electric field generated by the voltage exists only between the core wire and the outer conductor, that is, only in the space inside the outer conductor, The effect of the signal voltage does not appear in the space outside the conductor (shield effect).

The current flowing through the core wire passes through the transmitting oscillator and flows through the outer conductor in the opposite direction to the core wire. That is, the core wire and the outer conductor of the coaxial transmission line are equal in size, and current flows in opposite directions.

As viewed from the outside of the coaxial transmission line, the outer conductor and the current flowing inside thereof cancel each other out, so that no magnetic field is generated outside the coaxial transmission line due to the signal current flowing therethrough. Therefore, the transmission by the coaxial transmission line does not affect the outside by the electric signal transmitted therethrough.

§2: Description by Specific Example The ultrasonic probe 2 and the balanced output transmission circuit 7A of the ultrasonic diagnostic apparatus main body 1 have the same configuration as in FIG. The third embodiment is
This is an example in which two transmission signal lines 3 in the configuration of FIG. 2 are coaxial transmission lines.

The electric field generated by the potential difference between the core of the coaxial transmission line and the external conductor (the transmission voltage supplied to the transmitting oscillator) is confined inside the external conductor and does not appear outside.

Since the currents flowing through the core wire and the outer conductor have the same magnitude and opposite directions, the electric fields generated outside the outer conductor cancel each other out. Therefore, the influence of the transmission signal transmitted through the coaxial transmission line does not appear outside the coaxial transmission line.

(Explanation of the Fourth Embodiment) ... Refer to FIG. 5 FIG. 5 is an explanatory view of the fourth embodiment. The fourth embodiment will be described below with reference to FIG.

§1: Basic Description of Fourth Embodiment A balanced output type power amplifier configured without using a transformer generally has a complicated structure and a large scale.

If the output of the unbalanced type power amplifier, which can be realized more easily than the balanced output type, is converted into the balanced output using the balanced / unbalanced conversion function of the transformer, the first
The configuration of the embodiment can be easily realized.

§2: Description by Specific Example The fourth embodiment is an example in which the configuration of the balanced output transmission circuit 7A of the first embodiment shown in FIG. 2 is changed. That is, this is an example in which a transformer 22 is used on the output side as a balanced output type power amplifier in the configuration of FIG. 2 in order to obtain the output of a balanced signal. The ultrasonic probe of FIG. 5 is the same as that of FIG.

Generally, if the output of the unbalanced type power amplifier 19 which can be realized more easily than the balanced output type is converted into the balanced output using the balanced / unbalanced conversion function of the transformer 22, it becomes easy. A device similar to that of the first embodiment can be realized.

The balanced output type power amplifier shown in FIG.
Compared to that of FIG. 2, the addition of one transformer eliminates the need for one power amplifier and one phase division circuit. (Description of Fifth Embodiment) ... Refer to FIGS. 6 and 7 FIG. 6 is an explanatory view of the fifth embodiment, and FIG. 7 is a configuration diagram of an ultrasonic probe of the fifth embodiment. The fifth embodiment will be described below with reference to FIG.

§1: Basic Description of the Fifth Embodiment The fifth embodiment uses a transformer on the output side of the transmission circuit for the transmission oscillator whose one side (one transmission electrode) is grounded, and transmits the signal. This is an example in which two terminals on the power supply side are floated.

Since the path through which the transmission current flows is closed,
The current flowing out of the transformer on the output side of the transmission circuit and flowing into the transmission oscillator through one of the two transmission signal lines returns to the transformer of the transmission circuit through the other transmission signal line.

Therefore, currents having the same magnitude but opposite directions flow in the two transmission signal lines. In this example, the effect of the magnetic field produced by the current is canceled out. In addition, since there is no ground point other than the ground side of the transmission oscillator, no current flows between the ground points of the transmission side and the reception side.

Furthermore, since the transmission line of the transmission signal is completely separated from the reception side, the transmission current does not flow into the ground line on the reception side. Therefore, since the common impedance is not generated, the adverse effect of the voltage drop due to this is not generated.

§2: Description by Specific Example The configuration of the ultrasonic probe 2 shown in FIG. 6 is the same as that of FIG. The configuration of the balanced output transmission circuit 7A is the same as that in FIG. That is, also in this example, the transformer is used to float the two terminals on the side that supplies the transmission power.

In the fifth embodiment, one of the two electrodes of the transmission oscillator 10 is connected to the ground potential (connected to the ground line 23).
However, in addition to the ground-side transmission electrode of the transmission oscillator 10 and the ground-side reception electrode of the reception oscillator 11, the transmission signal line 3
Then, there is no connection point of the reception signal line 4, the transmission current path is closed, and the transmission current does not flow into the ground line on the reception side.

Therefore, no common impedance is generated,
There is no adverse effect of voltage drop due to this. Also, 2
In the transmission signal line 3 of the book, currents having the same magnitude but opposite directions flow, so that the influence of the magnetic field generated by the transmission current is canceled.

Next, the structure of the ultrasonic probe used in the fifth embodiment will be described with reference to FIG. As described above, in the third embodiment, the ground side of the transmitting oscillator 10 and the ground side of the receiving oscillator 11 are used by being connected, so that the ultrasonic probe has the configuration shown in FIG. It suffices to use the one having.

In this example, in the ultrasonic probe 2 shown in FIG. 2, the transmitting electrode 16 and the receiving electrode 18 are integrated, and this electrode is used as the ground side common electrode 24. That is, the transmission electrode 16 that is an electrode on the ground side of the transmission oscillator 10
And the grounding side receiving electrode 18 of the receiving vibrator 11 is connected from the beginning, and the grounding side common electrode 24 is manufactured integrally.

Particularly, in the case of a device in which the direction of the scanning line, that is, the direction of the ultrasonic beam is variable (steerable), for example, as shown in FIG.
A large number of 0s and reception oscillators 11 are used, and it is strictly required that their electrical characteristics and mechanical dimensional accuracy be the same.

Therefore, first, the whole ultrasonic transducer is integrally formed, electrodes are attached to both sides in advance, and the support 13 is formed.
After being bonded to the substrate, it is divided into a plurality of ultrasonic transducers (transmitting transducer and receiving transducer).

In this case, the electrode on the side closer to the support 13 is made into an integrated common electrode (ground side common electrode 24). Actually, there are 40 or more ultrasonic transducers,
Separately used for transmission and reception.

(Explanation of Sixth Embodiment)-See FIG. 8 FIG. 8 is an explanatory diagram of the sixth embodiment. The sixth embodiment will be described below with reference to FIG.

§1: Basic description of the sixth embodiment The sixth embodiment is such that the electric energy generated by the balanced output transmission circuit 7A in the fifth embodiment (see FIG. 6) is transferred to the ultrasonic transducer (transmission). This is an example in which a pair line is used for a transmission line for transmission to a vibrator and a reception vibrator. The sixth embodiment differs from the second embodiment in that one of the two signal lines is grounded.

Compared to the second embodiment, the effect of the magnetic field generated by the currents flowing through the two transmission signal lines is canceled out, but one conductor is grounded, so both conductors are grounded. The voltage is not symmetrical with respect to ground potential.
Therefore, this is different from the balanced transmission of the second embodiment.

§2: Description by Specific Example As shown in FIG. 8, a pair of wires is used for the transmission signal line 3 between the ultrasonic diagnostic apparatus body 1 and the ultrasonic probe 2. The rest of the configuration is the same as in FIG.

As described above, the effect of the magnetic field generated by the currents flowing through the two transmission signal lines 3 is canceled as compared with the second embodiment, but in the present embodiment, one of the conducting wires is used. Is grounded, the voltage on both conductors is not symmetrical with respect to ground potential. Therefore, this is different from the balanced transmission of the second embodiment.

(Explanation of Seventh Embodiment)-See FIG. 9 FIG. 9 is an explanatory view of the seventh embodiment. The seventh embodiment will be described below with reference to FIG.

§1: Basic description of the seventh embodiment The seventh embodiment is the same as the fifth embodiment (see FIG. 6) except that the electric energy generated by the transmission circuit is converted into ultrasonic transducers (transmission transducer and reception transducer). This is an example in which a coaxial transmission line is used as a transmission line for transmission to a vibrator.

This example differs from the third embodiment (see FIG. 4) in that
The difference is that the outer conductor of the coaxial transmission line is grounded. As in the third embodiment, the magnetic fields generated by the currents flowing through the core wire and the outer conductor cancel each other out.

Compared to the sixth embodiment (see FIG. 8), the effect of the transmission voltage applied to the core wire on the outside of the coaxial transmission line (electric field) is reduced due to the shielding effect of the coaxial transmission line.

§2: Description by specific example As shown in the drawing, the ultrasonic diagnostic apparatus main body 1 and the ultrasonic probe 2
A coaxial transmission line is used for the transmission signal line 3 between the and. The rest of the configuration is the same as in FIG.

By doing so, as described above, as compared with the sixth embodiment, because of the shielding effect of the coaxial transmission line,
The influence of the electric field exerted on the outside of the coaxial transmission line by the transmission voltage applied to the core wire is reduced.

(Description of Eighth Embodiment) ... See FIGS. 5 to 9 Hereinafter, an eighth embodiment will be described with reference to FIGS. 5 to 9. The eighth embodiment is a modified example of the embodiments shown in FIGS. 5 to 9, and the drawings are omitted.

§1: Basic explanation of the eighth embodiment The eighth embodiment is the same as the apparatus of the fourth to seventh embodiments.
The transformer used for the balanced output type power amplifier has a narrow band pass band characteristic to reduce unnecessary frequency components,
This is an example in which the voltage waveform supplied to the ultrasonic vibrator is a fundamental wave (sine wave) with little distortion.

In the pulse wave Doppler ultrasonic diagnostic apparatus, the transmitted ultrasonic wave requires a very wide band, whereas in the continuous wave Doppler ultrasonic diagnostic apparatus, the band of the transmitted ultrasonic wave may be narrow (theoretically. Has a single spectrum).

If the transmission waveform supplied to the transmission oscillator is distorted and contains unnecessary frequency components such as high frequencies, it is not preferable because it promotes the temperature rise of the transmission oscillator and mixes in the received signal as noise. Influence.

§2: Description based on a specific example Since it is the same as FIGS. (Description of Ninth Embodiment) ... See FIG. 10. FIG. 10 is an explanatory diagram of the ninth embodiment. The ninth embodiment will be described below with reference to FIG.

§1: Basic Description of Ninth Embodiment The ninth embodiment is the same as the devices of the fourth to seventh embodiments (see FIGS. 5 to 9) except that it has a power amplifier for transmission and a transmission oscillator. This is an example in which the transformer located between is provided with the function of impedance conversion.

The impedance of the ultrasonic oscillator is determined by its frequency response characteristics and mechanical structure, and does not necessarily give an appropriate load condition to the power amplifier for transmission, and the efficiency of the power amplifier for transmission is not limited. It causes problems such as deterioration.

Therefore, by performing impedance matching with the transformer, the efficiency of the power amplifier for transmission can be improved. It is ideal to perform impedance matching including the transmission line, but in general, compared with the wavelength (electrical on the transmission line) in the frequency band of the transmitted ultrasonic wave used in the ultrasonic diagnostic equipment. Therefore, the physical length of the transmission line is sufficiently short, and the impedance of the transmission line does not pose a problem in terms of transmission power efficiency.

§2: Description by Specific Example In FIG. 10, the receiving system is not shown. 9th
In the embodiment, the power amplifier 19 for transmission and the transmission oscillator 10 are used.
The transformer 22 located between the two has a function of impedance conversion.

In FIG. 10, when the turns ratio of the transformer 22 placed on the output side of the balanced output transmission circuit 7A is n: 1,
If the impedance of the transmission oscillator 10 is Zt at the frequency of the ultrasonic wave to be driven, the impedance of the transformer as seen from the transmission circuit and the load side including the transmission oscillator is Zt / n.

Strictly speaking, the transformer 22 and the transmission oscillator 1
It is necessary to correct the impedance determined from the relationship between the characteristic impedance of the transmission line between 0, the electrical length of the transmission line, and the wavelength (electrical on the transmission line) at the frequency of the transmitted ultrasonic wave. Generally, the influence on the frequency of the transmission ultrasonic wave used in the ultrasonic diagnostic apparatus and the length of the transmission line is sufficiently small and can be ignored.

[0131]

As described above, the present invention has the following effects. : It is possible to reduce crosstalk between transmission / reception and reduce unnecessary large-amplitude transmission signal components superposed on a signal input from the ultrasonic probe to the reception system.

As a result, it is possible to eliminate a factor of performance deterioration such as saturation of the amplification circuit of the reception system and to improve reception performance. : With a simple configuration, the performance of the continuous wave Doppler ultrasonic diagnostic apparatus is improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of the first embodiment.

FIG. 3 is an explanatory diagram of a second embodiment.

FIG. 4 is an explanatory diagram of a third embodiment.

FIG. 5 is an explanatory diagram of a fourth embodiment.

FIG. 6 is an explanatory diagram of a fifth embodiment.

FIG. 7 is a configuration diagram of an ultrasonic probe according to a fifth embodiment.

FIG. 8 is an explanatory diagram of a sixth embodiment.

FIG. 9 is an explanatory diagram of the seventh embodiment.

FIG. 10 is an explanatory diagram of the ninth embodiment.

FIG. 11 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

1 Ultrasonic diagnostic device body 2 Ultrasonic probe 3 transmission signal line 4 Received signal line 7 Transmitter circuit 8 Receiver circuit 10 Transducer (ultrasonic transducer on the transmitting side) 11 Receiving transducer (ultrasonic transducer on receiving side) 14 Piezoelectric material 15, 16 Transmitting electrode 17, 18 Receiving electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) A61B 8/00-8/15 G01S 15/00 G01N 29/00-29/28

Claims (5)

(57) [Claims] 1. An ultrasonic diagnostic apparatus body (1) having a transmission circuit (7) for transmitting / receiving a signal and a reception circuit (8), an ultrasonic transducer (10) on the transmission side, and reception. Side ultrasonic transducer (11) having an ultrasonic probe (2), the ultrasonic diagnostic apparatus body (1), and the ultrasonic probe
A transmission line (3, 4) for transmitting a signal between (2), and a transmission circuit (7) for the ultrasonic transducer (10) on the transmission side.
, The AC electric energy of a single frequency is continuously applied to radiate elastic wave energy, and the reflected elastic wave energy from the reflector is received by the ultrasonic transducer (11) on the receiving side. In the continuous wave Doppler ultrasonic diagnostic apparatus that converts the electrical signal into an electrical signal and processes the information included in the converted electrical signal in the ultrasonic diagnostic apparatus main body (1), the ultrasonic transducer (10 ) One of the transmitted power
One of the pole and the ultrasonic transducer (11) on the receiving side
The receiving electrode is structured to be grounded, and the secondary side is electrically connected to the transmitter circuit (7) from the ground potential.
Balanced output with isolated transformer (22) on the output side
Continuous wave Doppler ultrasonic diagnostic apparatus, characterized in that a type power amplification circuit is provided . 2. The continuous wave Doppler ultrasonic diagnostic apparatus according to claim 1, wherein the transmission line (3) for transmitting the electric energy generated by the transmission circuit (7) to the ultrasonic transducer (10) on the transmission side. )
A continuous wave Doppler ultrasonic diagnostic apparatus characterized by using a pair of wires . 3. A continuous wave Doppler ultrasound diagnostic apparatus according to claim 1, the electrical energy transmitting circuit (7) occurs, the transmission line path for transmitting the ultrasonic transducer of the transmitting side (10) A continuous wave Doppler ultrasonic diagnostic apparatus characterized by using a coaxial transmission line. 4. The method according to any one of claims 1 to 3.
Transformer (22) constituting a balanced output type power amplifier circuit in a continuous wave Doppler ultrasonic diagnostic apparatus
Of the AC voltage applied to the ultrasonic transducer (10) on the transmitting side.
Has a narrow band pass characteristic with the fundamental frequency as the center frequency
By using the transformer (22), high frequency can be obtained from the AC electric energy generated by the transmission circuit (7).
Remove the wave component and use it for the ultrasonic transducer (10) on the transmission side.
The supplied voltage waveform is the fundamental wave (sine wave) with less distortion.
So as continuous wave Doppler ultrasound diagnostic apparatus being characterized in that the. 5. The method according to any one of claims 1 to 3.
Transformer (22) constituting a balanced output type power amplifier circuit in a continuous wave Doppler ultrasonic diagnostic apparatus
A continuous wave Doppler ultrasonic diagnostic device characterized in that it has an impedance conversion function .