JPH0793929B2 - Ultrasonic diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a signal transmission path of an ultrasonic diagnostic apparatus, particularly an ultrasonic diagnostic apparatus in which a probe having a built-in preamplifier is connected to the apparatus main body through a connection cable. Regarding the improvement of.

[Prior Art] An ultrasonic diagnostic apparatus that transmits an ultrasonic beam into a subject and forms a tomographic image by a reflection echo obtained from a difference in acoustic impedance of tissue in the subject is well known, and adversely affects the tissue. Has the advantage of being able to observe inside without affecting
It plays an extremely important role as a means for diagnosing the affected tissue of the human body.

By the way, the S / S of the received signal is an important condition for obtaining clear and high-quality tomographic images in such an ultrasonic diagnostic apparatus.
One example is to keep the N ratio sufficiently high.

For this reason, various measures have been conventionally made, but as a particularly effective means, a preamplifier is provided in the ultrasonic probe, and the received signal is pre-amplified in the ultrasonic probe and then the device main body is connected via the connection cable. The method of sending to the side has been developed.

According to this method, particularly the high frequency component of the received signal is attenuated due to the influence of the capacity of the connection cable between the ultrasonic probe and the main body of the device, and external noise is picked up.
It is possible to prevent deterioration of the S / N ratio.

[Problems to be Solved by the Invention] However, when such a method of incorporating a preamplifier in a probe is adopted, it is possible to prevent deterioration of the S / N ratio, but on the other hand, the following adverse effects are involved.

First, the preamplifier, which is an active element, requires a dedicated power supply. Therefore, when such a configuration is adopted, a power supply lead wire and a lead wire for signal transmission / reception, that is, for applying a drive pulse to the vibrator are used. It is necessary to provide at least three kinds of conducting wires, namely, a conducting wire for transmitting the reception signal amplified by the preamplifier to the apparatus main body side.

This inevitably leads to an increase in the diameter of the connection cable that connects the device body and the probe, and the cable shape becomes extremely thick and rugged, especially when using an array-type transducer in which multiple vibration elements are arranged. And
As a result, the operability, which is one of the important factors that affect the performance of the ultrasonic diagnostic apparatus, is significantly impaired.

As a countermeasure against such a problem, it is considered to provide a dedicated battery for supplying power to the preamplifier in the ultrasonic probe, but this directly causes the ultrasonic probe itself to become large and the battery life. Inevitably, the inconvenience of reduced reliability due to Although this eliminates the need for a power supply conductor, it still requires separate conductors for transmission and reception, so it does not contribute much to the reduction of the diameter of the connection cable, which is very useful for improving operability. Absent.

Further, in the conventional device configuration as described above, when a preamplifier is provided in the probe to improve the S / N ratio of the received signal and give priority to the sharpness of the image, a certain effect can be obtained. However, in ultrasonic diagnosis, it is often necessary to prioritize miniaturization of the probe over such reception characteristics itself depending on the site to be diagnosed or the situation.In such a case, the configuration inside the probe is inevitably necessary. The preamplifier is placed on the main body side of the device because only a minimum number of elements are required. However, such a situation is not taken into consideration in the conventional device configuration, and since the device body has a structure intended only for a probe with a built-in preamplifier, a dedicated device body must be provided for each type of probe. However, there is a problem that the versatility of the apparatus body is extremely low.

OBJECT OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and the object thereof is to reduce the number of cables between the ultrasonic probe and the apparatus body while ensuring a sufficiently high S / N ratio of the received signal with a simple configuration. It is an object of the present invention to provide an ultrasonic diagnostic apparatus which can be reduced in number to improve operability, and can be adapted to a probe type with a built-in preamplifier.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a device main body having a transmitter / receiver connected to a power supply, and a probe having a vibrator and a preamplifier built therein, a connection cable. In the ultrasonic diagnostic apparatus that transmits and receives the drive pulse and the ultrasonic echo signal via the probe, the probe prevents the drive pulse transmitted from the apparatus main body at the time of transmission from flowing into the preamplifier side and vibrates. A drive pulse blocking diode inserted between the connection cable and the preamplifier for supplying only to the child side, and the connection for causing the ultrasonic echo signal to flow only into the preamplifier side. An echo signal blocking diode interposed between a cable and the vibrator, the apparatus body is connected to the preamplifier via the connection cable, and the connection A main body side amplifier that receives a voltage-current exchanged reception signal sent via a cable and a main body side amplifier and a main body side end of the connection cable are connected, and the drive pulse is connected to the connection cable. Connected between the output pulser for output, the main body side amplifier and the main body side end of the connection cable,
A preamplifier power supply for applying a voltage having a polarity opposite to that of the drive pulse to the connection cable as a drive voltage of the preamplifier, wherein the voltage of the preamplifier power supply is the connection cable and the drive. A single connection cable can be used for each oscillator to send and receive signals between the device body and the probe and to supply voltage to the preamplifier from the device body through the pulse blocking diode. It is characterized in that it is configured in.

[Operation] According to the present invention configured as described above, the oscillator drive pulse output from the transmission pulser of the apparatus body is applied to the probe by the drive pulse blocking diode inserted between the connection cable and the preamplifier. All of them are used for oscillator excitation without going around the built-in preamplifier side.

Then, the ultrasonic echo signal reflected from the tissue in the subject does not flow backward to the drive pulse supply line by the echo signal blocking diode inserted between the connection cable and the oscillator, and does not go to the main body side without fail. Then, after being subjected to a predetermined amplifying effect, the signal is input to the receiver in the main body of the apparatus via the connection cable.

Then, the voltage supply to the preamplifier built in the probe is performed by the power source on the device main body side through the connection cable and the drive pulse blocking diode at the time of reception.

As a result, a single connecting cable is used for exchanging the drive pulse and ultrasonic echo signal between the device body and the probe and for supplying the voltage from the device body to the preamplifier. It is possible to obtain a sonic diagnostic device.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

In the figure, the same components as those of the conventional device are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows a circuit configuration example of the ultrasonic diagnostic apparatus according to the present invention.

In the figure, the ultrasonic diagnostic apparatus as a whole is shown in a device body, a connection cable, and an ultrasonic probe, which are roughly divided into three parts with a chain line to clarify the boundaries of the elements included in each part.

A characteristic of the device of the present invention is that a single connecting cable is used for transmitting / receiving a transducer driving pulse and an ultrasonic echo signal between the device main body and the ultrasonic probe and for supplying a voltage to a preamplifier built in the ultrasonic probe. With this, it is possible to secure a high S / N ratio of the received signal by incorporating a preamplifier on the probe side and to suppress the diameter of the connecting cable to the minimum to obtain sufficient flexibility. It is possible to achieve both of the above, and it is possible to obtain an ultrasonic diagnostic apparatus having both reception performance and operability.

The apparatus main body 10 includes a transmitter 16 and a receiver 18, and sends the driving pulse output from the transmitter 16 into the ultrasonic probe 14 via the connection cable 12.

The ultrasonic probe 14 is a transducer 20 for converting the drive pulse that has been sent to an ultrasonic wave, and an ultrasonic echo signal from the inside of the living body that is input via the transducer 20 before being sent to the apparatus body 10 side. And a preamplifier 22 for preliminarily performing an amplifying action to secure a high S / N ratio. As previously mentioned,
By the action of the preamplifier 22, it is possible to effectively prevent the ultrasonic echo signal reflected from the living body from being attenuated in the middle of the transmission path, or the S / N ratio thereof being lowered due to the inclusion of noise.

The ultrasonic echo signal that has entered the apparatus main body 10 side through the connection cable 12 is input to the receiver 18, is subjected to a predetermined amplification action, and is then output to the image display processing unit in the subsequent stage.

The present invention is characterized in that the apparatus main body 10 and the ultrasonic probe 14 having the built-in preamplifier 22 exchange signals with a single connection cable 12, and as will be described later, a main role for this purpose. Driving pulse blocking diode 24
And an echo signal blocking diode 26 are respectively inserted between the connection cable 12 and the preamplifier 22 and between the connection cable 12 and the oscillator 20, and at the front stage of the receiver 18 at the time of transmission. A drive pulse blocking diode 28 for blocking the inflow of the drive pulse into the receiver 18 in FIG.

Next, the operation will be described.

First, when a transmission trigger pulse Tp is applied to the transmission pulser 30 in the transmitter 16 during transmission, a high-voltage drive pulse, in the illustrated example, a negative-side falling pulse is generated in the transmission pulser 30. .

A capacitance 32 for removing a DC portion from the output is inserted in the subsequent stage of the transmission pulser 30. As a result, as shown in the graph of FIG. 2, the point A in the figure is a negative potential exceeding -100V. Will be drawn to.

At this time, the point A is maintained by the positive side voltage supply of about + several volts from the power source Vcc, and the drive pulse blocking diodes 24 and 28 which have been energized accordingly
Is momentarily de-energized. This allows the preamplifier
It will be appreciated that drive pulse flow into 22 and receiver 18 is blocked and transistors 34 and 36 are protected from negative high voltages.

On the other hand, only the echo signal blocking diode 26 becomes a forward bias at the same time when the potential at the point A suddenly drops, and is energized. As a result, the drive pulse from the transmission pulser 30 is transmitted to the cable 12 and the echo signal blocking diode 26. Is applied to the electrode of the vibrator 20 via the electromagnetic wave, converted into an ultrasonic pulse beam by the exciting action of the piezoelectric material, and emitted into the living body.

In the illustrated example, for convenience of description, only the configuration corresponding to a single vibrator is extracted and drawn. Therefore, in the case of an array type transducer including a plurality of vibrating elements, it is only necessary to connect circuits having the same configuration in parallel for each element.

When the oscillator 20 is excited, the voltage of the oscillator 20 is applied to the gate of the transistor 34 via the resistor R1, but the diode 40 and 42 clamp the forward voltage (for example, about 0.7 V). Therefore, the drive pulse does not destroy the transistor 34.

The transmission operation is performed by the action of each of these elements, and the drive pulse excites only the oscillator 20 that is the input target, and faithfully retains its original function without adversely affecting other elements. Understood to fulfill.

Next, the receiving operation will be described.

Basically, in the present embodiment, it is considered that all are in the receiving state except the time of transmitting the driving pulse described above after the power is input. A bias current is supplied through the connection cable 12 and the drive pulse blocking diode 24. Similarly, a bias current is supplied to the transistor 36 of the receiver 18 via the resistor R4 and the drive pulse blocking diode 28.

As described above, the point A is kept at a DC positive potential of about several volts in this receiving state, and the echo signal blocking diode 26 is in a reverse bias and is in an off state.

Here, the ultrasonic echo signal from the reflecting object in the living body undergoes voltage conversion by the transducer 20, but the received ultrasonic echo signal voltage exceeds the point A potential of about several volts and is turned off. An echo signal blocking diode 26
Is not high enough to energize.

Therefore, the echo signal blocking diode 26 remains off even during this echo signal voltage conversion, and the received signal voltage Vs is directly applied to the gate of the transistor 34 via the resistor R1. As a result, a signal current represented by the following formula flows through the drain of the transistor 34, and this current flows into the point A of the device body 10 through the connection cable 12.

(However, gm: mutual conductance of the transistor 34) The ultrasonic echo signal is input from the point A to the emitter of the transistor 36 functioning as a grounded base. At this time, the series ON resistance component of the drive pulse blocking diode 28 is If the input impedance of the transistor 36 including the above is Zitr2, the following relationship exists.

| Zitr2 | << R4 (2) Here, it is assumed that the transmission pulser 30 maintains a high impedance state except during the transmission period and does not affect reception.

If this relationship is maintained, the signal current is is all considered to flow into the emitter of the transistor 36.

The transistor 36 plays a role as a kind of current-voltage converter, and when the current amplification factor is sufficiently large, the emitter current and the collector current become almost equal, and as a result, the signal voltage V0 appearing at the collector terminal is Is expressed as

Here, if V0 / Vs is defined as the voltage amplification factor Av of the preamplifier, Becomes Furthermore, under the condition of 1 << gm ・ R3 It can be expressed by a simple formula.

As described above, according to the present embodiment, the drive pulse at the time of transmission is the reverse flow to the transistor 34 in the preamplifier 22 by the drive pulse blocking diode 24 inserted between the connection cable 12 and the preamplifier 22. The ultrasonic echo signal from the living body is applied only to the oscillator 20 that is the desired supply target without causing the destruction due to the inflow, and the ultrasonic echo signal from the living body is connected to the oscillator.
The echo signal blocking diode 26 provided between the device 20 and the device 20 always sends the signal to the device body 10 side through the preamplifier 22.
The voltage is supplied from Vcc to the preamplifier 22 via the connecting cable 12 without any problem. Further, by disposing the drive pulse blocking diode 28, it is possible to surely prevent the drive pulse from flowing into the transistor 36 of the receiver 18 at the time of transmission, and to connect the single connection cable 12 from (1) the transmitter 16 to the oscillator. Drive pulse supply to 20, (2) Transducer 20 to receiver
Transmission of ultrasonic echo signals to 18, (3) ultrasonic probe
It becomes possible to share the three functional purposes of supplying the voltage from the power source Vcc of the device body 10 to the preamplifier 22 in the unit 14.

As a result, the pre-amplifier 22 is provided in the ultrasonic probe 14 to secure a high level of the S / N ratio of the received signal, and the operability of the probe 14 is improved by making the connection cable 12 single. It is possible to realize an ultrasonic diagnostic apparatus that can effectively meet both of the above conditions.

Next, a second embodiment of the ultrasonic diagnostic apparatus will be described as a reference example with reference to FIG. This embodiment shows a state in which the apparatus main body 10 having the same configuration as that of the first embodiment is connected to an ultrasonic probe without a preamplifier. As already mentioned, when it is necessary to insert an ultrasonic probe into a body cavity or as an ultrasonic probe for an affected area monitor during surgery, the physical scale of the probe itself can be miniaturized despite the reception performance. This is the first condition. Under these circumstances, the components in the probe are naturally narrowed down to the minimum necessary, and therefore the preamplifier is removed from the inside of the probe.

Conventionally, when the structure in which the preamplifier is embedded in the probe is adopted, the apparatus main body side must be provided with a dedicated circuit configuration corresponding to the structure, and the ultrasonic probe without the preamplifier In reality, there is no compatibility, and a large and expensive device body is required for each probe.

The second embodiment solves these problems and realizes versatility for both the preamplifier built-in type probe and the non-built-in type probe in the same apparatus body.

Therefore, in the device according to FIG. 3, the circuit on the device main body 10 side is the same as that in FIG. 1, and only the internal structure of the ultrasonic probe 14 is different.

As a result, the operation at the time of transmission is no different from that in the case of FIG. 1, so only the operation at the time of reception will be described.

Impedance Zitr of transistor 36, which is grounded
2 and the equivalent signal source impedance Ztd of oscillator 20 is | Ztd | >> |
If there is a relation of Zitr2 |, all received signals from the oscillator 20 flow into the point A in the form of current is. At this time, the transistor
The voltage V0 appearing at the collector terminal of 36 can be expressed as V0 = isR7 (6). The voltage amplification factor Av in this case is Is.

Therefore, if R3 in FIG. 1 is selected so that R3 | Ztd | is obtained from the above equations (5) and (7), it can be used for both preamplifier built-in type probe and non-prebuilt type probe. The signal amplification factor can be kept constant.

FIG. 4 shows a third embodiment of the device of the present invention.

A characteristic of this embodiment is that instead of the resistor R1 shown in FIG. 1, Ci is used as the capacitor coupling provided between the vibrator 20 and the transistor 34, and this is particularly the power of the driving pulse during transmission. Is sufficiently large and the oscillator 20 can be sufficiently excited without inserting a relatively large resistance between the oscillator 20 and the transistor 34 as shown in FIG. To do.

FIG. 5 shows a fourth embodiment of the device of the present invention.

A characteristic feature of this embodiment is that a capacitor C3 is provided between the connection cable 12 and the receiver 18 for AC coupling, whereby the bias current flowing in the transistor 34 in the amplifier and the device main body. The DC operating points of the transistor 36 in the side receiver can be independently selected, which facilitates circuit design.

FIG. 6 shows a fifth embodiment of the device of the present invention.

The present embodiment is characterized in that the oscillator 20 is excited by a positive drive pulse having a polarity opposite to that of the power supply -Vcc for the preamplifier 22, and the basic circuit configuration is the same as that of the device shown in FIG. is there. Therefore, the function and effect are the same as those in the first embodiment.

[Effects of the Invention] As described above, according to the present invention, transmission / reception of a transmission / reception signal between the ultrasonic probe with built-in preamplifier and the device main body and the device main body with a single connection cable having a relatively simple structure. Therefore, a voltage can be supplied to the preamplifier in the probe, an ultrasonic echo signal with a high S / N ratio can be received without impairing the operability, and a high-quality image can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of the device of the present invention, FIG. 2 is a graph showing a time change of a transmission / reception signal voltage in the device of the present invention, and FIG. 3 is a second embodiment of the device of the present invention. FIG. 4 is a circuit configuration diagram showing a third embodiment of the present invention device, FIG. 5 is a circuit configuration diagram showing a fourth embodiment of the present invention device, and FIG. It is a circuit block diagram which shows 5th Example. 10 …… Main unit 12 …… Connection cable 14 …… Ultrasonic probe 16 …… Transmitter 18 …… Receiver 20 …… Transducer 22 …… Preamplifier 24 …… Driving pulse blocking diode 26 …… Echo signal Blocking diode.

Claims (1)

[Claims] 1. An ultrasonic wave for transmitting and receiving a drive pulse and an ultrasonic echo signal through a connection cable between a device body having a transceiver and connected to a power source, and a probe having a vibrator and a preamplifier built therein. In the diagnostic device, the probe is provided with the connection cable and the front end in order to prevent the drive pulse transmitted from the main body of the device at the time of transmission from flowing into the preamplifier side and supply only to the transducer side. A drive pulse blocking diode interposed between an amplifier and an echo signal interposed between the connection cable and the vibrator for allowing the ultrasonic echo signal to flow only to the preamplifier side. And a blocking diode, wherein the device body is connected to the preamplifier via the connection cable,
A main body side amplifier that receives a voltage-current exchanged reception signal sent via the connection cable, and a main body side amplifier connected to the main body side end of the connection cable, and drive to the connection cable. A pulse generator for outputting a pulse is connected between the main body side amplifier and the main body side end of the connection cable, and a voltage having a polarity opposite to that of the drive pulse is applied to the connection cable as a drive voltage of the preamplifier. A power source for the preamplifier, wherein the voltage of the power source for the preamplifier is applied to the preamplifier via the connection cable and the drive pulse blocking diode, An ultrasonic diagnostic apparatus, wherein transmission and reception and voltage supply from the apparatus body to the preamplifier can be shared by a single connection cable for each transducer.