JP2001046379A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic device with which an ultrasonic diagnostic image may be obtained at a frequency suitable to a diagnostic part with good resolution in a shallow part and good sensitivity in a deep part by an ultrasonic vibrator transducer of a composite piezoelectric substance and allows the reduction of the diameter of an ultrasonic probe. SOLUTION: The ultrasonic vibrator transducer 12 formed of the composite piezoelectric substance having a frequency characteristic of a wide band is arranged at the front end of an insertion part 5 of the ultrasonic probe 2. When a connector 8 is connected to an ultrasonic observation device 3, signal transmission pulses are impressed from a signal transmission circuit 15 to the composite piezoelectric substance and the echo signal received in the composite piezoelectric substance is inputted to the signal reception circuit 16. A control section 19 variably controls the number of waves and central frequency of the signal transmission pulses from the signal transmission circuit 15, variably controls the resonance frequency characteristic of the signal reception circuit 16 and displays the ultrasonic diagnostic image by extracting the echo signals with the good resolution in the shallow part and the good sensitivity in the deep part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus for irradiating an ultrasonic wave to a tissue or the like in a body, and obtaining an ultrasonic tomographic image of the tissue or the like by utilizing a characteristic of reflection at a boundary surface of acoustic impedance. .

[0002]

2. Description of the Related Art In recent years, in the medical field, an ultrasonic pulse is transmitted from an ultrasonic transducer as an electroacoustic transducer to a living tissue as an object to be observed (or a sound field medium) and is reflected from the living tissue. There have been proposed various ultrasonic observation apparatuses that receive an echo of an ultrasonic pulse by an ultrasonic transducer and display information collected from a living body as an ultrasonic tomographic image as a visible image.

An ultrasonic vibrator used for such an ultrasonic observation device or the like uses a composite piezoelectric body having a structure in which a resin is filled in a gap between a plurality of columnar piezoelectric bodies arranged at an interval from each other. The child has a wide acoustic impedance and good matching with living tissue. Further, the composite piezoelectric vibrator has a low resonance sharpness (Q) and has a wide frequency characteristic.

[0004]

However, while the composite piezoelectric vibrator has a wide frequency band, the Q is low, so that the sensitivity is lower than that of the conventional vibrator. To compensate for the lack of sensitivity, connect an inductance in parallel with the capacitance component of the oscillator,
A method of forming a parallel resonance circuit, increasing impedance in a specific frequency region, and increasing sensitivity has been used. However, when such a method is used, a wide frequency band, which is a feature of the composite piezoelectric vibrator, is significantly narrowed.

[0005] Inserting a tuning inductance into the ultrasonic vibrator limits the frequency band due to the above-described problem, and even if the frequency of the transmission energy applied to the ultrasonic vibrator is changed. The frequency band of the received echo is fixed substantially constant by the tuning inductance.

Therefore, conventionally, two types of oscillators having different frequencies are used, and the diagnosis is performed by selecting and using the frequency in accordance with the diagnosis site. However, by using a plurality of ultrasonic transducers, the insertion portion of the ultrasonic probe becomes thick.

(Object of the Invention) The present invention has been made in view of the above-mentioned points, and uses an ultrasonic vibrator formed of a composite piezoelectric body, and has a high resolution of 12 or 20 MHz in a shallow portion.
Ultrasound diagnostic equipment that can observe at high frequencies such as at high frequency and perform ultrasonic diagnostics at a low frequency side such as 7.5 MHz at a frequency suitable for the diagnostic site with high sensitivity and at the same time can reduce the diameter of the ultrasonic probe. The purpose is to provide.

[0008]

An electroacoustic transducer for transmitting an ultrasonic pulse into a sound field medium and receiving a reflection echo from the sound field medium is composed of a plurality of columnar piezoelectric bodies. An ultrasonic diagnostic apparatus comprising: an ultrasonic probe having a built-in ultrasonic transducer formed of a composite piezoelectric body composed of a resin filled with an ultrasonic probe; and an ultrasonic observation apparatus to which the ultrasonic probe can be connected. A transmission circuit that excites the composite piezoelectric body and can arbitrarily change the frequency characteristics of the ultrasonic pulse, and the reception frequency band and the center frequency can be changed according to the frequency characteristics of the ultrasonic pulse and the propagation time of the ultrasonic pulse And a control unit capable of changing the frequency characteristics and the reception frequency band of the ultrasonic pulse by the transmission circuit, so that the reception frequency band and the center frequency can be changed according to the propagation time. For example, in the shallow part where the propagation time is small, the reception frequency band is set on the high frequency side to receive with good resolution, and in the deep part where the propagation time is long, the reception frequency band is set on the low frequency side and the deep part is received with good sensitivity. An ultrasonic diagnostic image suitable for a diagnostic site can be obtained, and the diameter of the ultrasonic probe can be reduced by one ultrasonic transducer.

The control unit controls the transmitting circuit to arbitrarily change the frequency band of the ultrasonic pulse within the response frequency band of the composite piezoelectric body, and the receiving circuit controls the frequency band of the ultrasonic pulse. And, according to the propagation time of the ultrasonic pulse, the reception frequency band can be shifted to a low frequency within the frequency band of the ultrasonic pulse. In a deep part where the propagation time is long, a reception frequency band is set on the low frequency side, and the deep part is received with high sensitivity to obtain an ultrasonic diagnostic image suitable for a diagnostic part.

The control unit can control the frequency band of the ultrasonic pulse by the transmitting circuit and the receiving frequency band by the receiving circuit by control signals from an ultrasonic scope and an ultrasonic observation device, so that the ultrasonic wave can be controlled. The characteristics and the like of an ultrasonic diagnostic image obtained by a composite piezoelectric body from a scope or the like can be controlled.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIGS. 1 to 8 relate to an embodiment of the present invention, FIG. 1 shows a schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIG. 3 shows a configuration of a composite piezoelectric body constituting an ultrasonic vibrator provided at the tip of FIG. 3, and FIG.
4 shows the configuration of the transmission circuit, FIG. 5 shows the frequency band and power in the case of transmission pulses having different wave numbers, FIG. 6 shows the configuration of the reception circuit, and FIG. 7 shows the voltage applied to the varicap diode over time. FIG. 8 is a diagram for explaining the operation of the receiving circuit.

As shown in FIG. 1, an ultrasonic diagnostic apparatus 1 according to one embodiment of the present invention is inserted into a body cavity or the like and transmits and receives ultrasonic waves, and the ultrasonic probe 2 is detachable. , An ultrasonic observation device 3 that performs signal processing for transmitting and receiving ultrasonic waves, and a monitor 4 that displays a corresponding ultrasonic tomographic image when a video signal is input from the ultrasonic observation device 3. Consists of

The ultrasonic probe 2 has an elongated insertion portion 5 for easy insertion into a body cavity, an operation portion 6 provided at a rear end of the insertion portion 5, and a cable extending from the operation portion 6. Part 7
A connector 8 is provided at the rear end of the cable section 7, and the connector 8 is detachably connected to the ultrasonic observation apparatus 3.

A flexible shaft 11 is inserted into the insertion portion 5, for example.
A composite ultrasonic vibrator 12 is attached to the tip of 1.
The rear end of the flexible shaft 11 is connected to a drive unit (not shown) such as a rotary drive motor in the operation unit 6.

By rotating the flexible shaft 11 by the driving unit, the ultrasonic vibrator 12 attached to the tip of the flexible shaft 11 is rotationally driven to transmit ultrasonic waves radially in a direction perpendicular to the axis of the insertion unit 5. Radial scanning can be performed. The ultrasonic vibrator 12 is electrically connected to a transmission circuit 15 and a reception circuit 16 in the ultrasonic observation apparatus 3 via a signal line 13 inserted into the flexible shaft 11 and further from a connector 8 via a slip ring or the like in the operation unit 6. Connected.

The transmission circuit 15 generates a transmission pulse, and transmits the transmission pulse to the ultrasonic vibrator 1 as an electroacoustic transducer.
2 to be excited to transmit an ultrasonic pulse.
The receiving circuit 16 amplifies the echo signal received by the ultrasonic transducer 12 and converted into an electric signal and outputs the amplified signal to the signal processing circuit 17.

The signal processing circuit 17 performs logarithmic amplification and detection of the band-limited received echo, performs A / D conversion, writes the echo signal data into the memory, converts the coordinate of the echo signal data, and performs D / A conversion. Generates a video signal and outputs it to the monitor 4
And an ultrasonic tomographic image is displayed on the display surface of the monitor 4.

Further, for example, the operation unit 6 of the ultrasonic probe 6 is provided with a frequency switching unit 18 for instructing frequency switching, and an instruction signal of the frequency switching unit 18 is supplied to a control unit 19 in the ultrasonic observation apparatus 3. The control unit 19 detects the frequency switching instruction signal and controls the characteristics of the transmission circuit 15 and the reception circuit 16.

In the present embodiment, one ultrasonic transducer 12 is built in the tip of the insertion section 5 of the ultrasonic probe 2 so that the outer diameter of the insertion section 5 can be reduced. As shown in FIG. 2, the ultrasonic vibrator 12 has a columnar piezoelectric body having an electroacoustic conversion function, and a plurality of piezoelectric bodies 21 are two-dimensionally arranged, for example, on a disk portion. 2
2 made of a composite piezoelectric material. The frequency characteristic of this composite piezoelectric body is much wider than that of a conventional ultrasonic transducer using a single piezoelectric body, and has a wide frequency range of, for example, 4 MHz to 22 MHz. Therefore, as will be described later, the transmission pulse for driving the composite piezoelectric body, the center frequency of the transmission pulse when receiving and extracting the echo signal component, and the resonance characteristics of the receiving circuit 16 are variably controlled to thereby provide one ultrasonic wave. An ultrasonic diagnostic image such as that obtained by a plurality of ultrasonic transducers having different frequency characteristics is obtained by the transducer 12.

First, referring to FIGS. 3 (A), 3 (B) and 3 (C), an ultrasonic vibrator 12 made of a composite piezoelectric material used in the present embodiment and an ultrasonic vibrator 61 employed in a conventional example will be described. The difference in the characteristics of FIG. 3C shows a case where a conventional ultrasonic vibrator 61 is employed as an ultrasonic probe. In this case, PZT is used as the ultrasonic vibrator 61, and the ultrasonic vibration is used as matching for improving sensitivity. A coil (inductance) 62 is inserted in parallel with the child 61. A parallel resonance circuit is formed by the inductance 62 and the capacitance of the ultrasonic transducer 61.

An impulse drive is performed on the ultrasonic resonator 61 from the transmission circuit to the parallel resonance circuit. Since the transmission pulse is an impulse, it ideally has a constant frequency characteristic in any frequency band from DC.

However, even if the ultrasonic transducer 61 is impulse-driven by the transmission circuit, the resonance circuit has a very narrow band, and as shown in the upper right part of FIG. The transfer characteristic is about 5 cycles. In this case, the frequency characteristic has a narrow frequency characteristic of, for example, 6 to 9 MHz, as shown in the lower right part of FIG.

The above values are uniquely determined by the ultrasonic transducer 61 and the matching inductance 62. From the above description, even if the setting conditions of the transmission circuit are changed, the frequency characteristics of the transmission circuit hardly affect the reception echo.

On the other hand, in the present embodiment, the ultrasonic vibrator 12 made of a composite piezoelectric body is employed, and FIG. 3A shows the characteristics in the case of the impulse drive in this case.

As described with reference to FIG. 2, the resin 22 is provided in the gap between the plurality of columnar piezoelectric bodies 21 arranged at an interval from each other.
Transducer 12 Using Composite Piezoelectric Structure Filled with Insulator
Has low acoustic impedance and good matching with living tissue.

The ultrasonic vibrator 12 made of the composite piezoelectric material has a low resonance sharpness (Q) and has a wide frequency characteristic as shown on the right side of FIG.

The composite piezoelectric body has good reception sensitivity, and has the same sensitivity as the conventional one without forming a matching circuit unlike the conventional one. And the frequency characteristic of the received echo is 4-2
It extends to 2MHz. Since the frequency band of the ultrasonic vibrator 12 is very wide as described above, the influence of the characteristics of the transmission circuit 15 greatly affects the received echo signal.

Therefore, as shown in FIG. 3B, when a transmission pulse is set to one cycle by the transmission circuit 15, the reception echo frequency band is wide, specifically 4 to 20 MHz, as described later.
z.

FIG. 4 shows a configuration example of the transmission circuit 15. The trigger signal output from the control unit 19 is applied to a trigger generator 31, and synchronized with the trigger signal, the trigger generator 3
1 generates a trigger. In the case of FIG. 3, as a specific example,
For example, a case where one transmission pulse is generated is shown,
In this case, the trigger generator 31 sequentially outputs the first trigger and the second trigger. More specifically, the trigger generator 3
1 generates a first trigger of about 50 ns, and generates a second trigger of about 50 ns with a delay of 50 ns from the first trigger.

The first trigger and the second trigger are FETs, respectively.
After being input to the drivers 32a and 32b and amplified respectively, they are applied to the gates of the first FET 33a and the second FET 33b, and the first FET 33a and the second FET 33b respectively.
The drain-source between b is turned on.

The drains of the first FET 33a and the second FET 33b are respectively connected to one ends of two primary windings 34a and 34b of a pulse transformer 34, and the other ends are connected to a resistor 35, respectively.
a, 35b are connected to the high voltage power supply terminal HV, and the sources of the first FET 33a and the second FET 33b are connected to the ground. The connection points between the primary winding 34a and the resistor 35a and between the primary winding 34b and the resistor 35b are connected to the ground via capacitors 36a and 36b.

The secondary winding 34 of the pulse transformer 34
A resistor 37 is connected in parallel to c and serves as an output terminal of the transmission pulse, one end of which is connected to the ground.
As shown in FIG. 4, the direction of each winding in the pulse transformer 34 is such that the primary winding 34b is opposite to both ends of the primary winding 34a and the secondary winding 34c, as indicated by dots at the beginning of the winding. Connected.

Therefore, the first winding connected to the primary winding 34a
When the FET 33a is turned on, the current flowing through the primary winding 34a causes the second FET 33b connected to the primary winding 34b to be turned off in response to an output waveform induced in the secondary winding 34c.
In the case of N, the output waveform induced in the secondary winding 34c has an opposite phase due to the current flowing through the primary winding 34b, and is synthesized as shown in FIG.
The transmission pulse of one cycle (one wave) is generated and applied to the ultrasonic transducer 12 formed of the composite piezoelectric body.

Although FIG. 4 shows a case where one transmission pulse is generated, the first to third triggers are generated by the trigger generator 31.
By generating triggers, first to fourth triggers,
It is also possible to generate 1.5 and 2 transmission pulses.

FIG. 5 is a schematic diagram showing frequency bands and powers of transmission pulses having different wave numbers (specifically, one, 1.5, and two transmission pulses). Generally, the frequency characteristic of a one-cycle pulse can be expressed by the following equation.

F − = (X−1) / X * F, F + = (X + 1) / X * F where F−: lower limit frequency, F +: upper limit frequency, F: center frequency, X = cycle number For example, 10 MHz, one cycle frequency band is 0
２０20 MHz. 3.33 to 16.6 for 1.5 waves
The frequency is 5 to 15 MHz for 7 MHz and two waves. As described above, since the composite piezoelectric body has a wide frequency band of 4 to 22 MHz, the frequency band of the reception echo can be changed by changing the wave number and center frequency of the transmission pulse generated by the transmission circuit 15.

The total energy of the center frequency is one wave
Then, 1.5 times for 1.5 waves, 2 times for 2 waves, and the sensitivity increases when the wave number is increased. The above 1.5
In the cycle, the center frequency is changed.

The center frequency (transmitting circuit pulse width) is 7.5
MHz and 15 MHz, the frequency band becomes 2.
It can be varied from 5 MHz to 12.5 MHz and from 5 MHz to 25 MHz.

Considering the frequency band of the composite piezoelectric material, the total frequency band is 4 MHz to 12.5 MHz to 2 MHz.
It becomes 2 MHz, and the frequency band of the reception echo can be changed by the transmission circuit 15.

In the present embodiment, by controlling the wave number and the center frequency of the transmission pulse applied from the transmission circuit 15 via the control unit 19 to the composite piezoelectric body having such a wide-band frequency characteristic, The frequency characteristics, more specifically, the frequency band, the power, and the like of the ultrasonic pulse generated and emitted to the observation target side can be arbitrarily changed.

The receiving circuit 16 can variably set the frequency characteristic of the transmitted ultrasonic pulse, specifically, the receiving frequency band within the frequency band of the ultrasonic pulse. The receiving frequency band can be shifted to a lower frequency side within the frequency band of the ultrasonic pulse according to the distance of the ultrasonic wave reflected from the observation object side).

In this case, the ultrasonic pulse has a sufficiently wide frequency band, and the propagation frequency of the ultrasonic pulse is reduced by shifting the reception frequency band to the lower side as the propagation time of the ultrasonic pulse increases. In the region, it is possible to receive on the high frequency side and obtain an echo signal with high resolution, and in the region where the propagation time of the ultrasonic pulse is long, receive on the low frequency side and obtain an echo signal with good S / N to the deep part. I can do it.

FIG. 6 shows a specific configuration of the receiving circuit 16 to which the received echo signal is input. After the reception echo signal is input to the amplifier 41 and amplified, for example, three switches S1 to S3 and each switch S
I (I = 1, 2, 3) is applied to one end of, for example, three coils L1 to L3 via a resistor RI, and each coil L
The other end of I is connected to the ground via, for example, three switches S1 to S3 constituting the changeover switch 44.

A series circuit of a capacitor C1, a variable capacitance (varicap diode) 44 and a capacitor C2 is connected in parallel with the series circuit of the coil LI and the switch SI, and the anode of the varicap diode 44 is connected to the ground. A varicap control voltage is applied to the cathode of the cap diode 44 from the controller 45 via the resistor R.

The controller 45 includes a controller 1
9, a control signal is applied, and the control signal controls the switching of the changeover switches 42 and 43 and the varicap control voltage.

In this case, a resistor RI in series with the switch SI turned on by the changeover switch 42 and an
The parallel resonance occurs due to the coil LI in series with the N-switched switch SI and the capacitance in parallel with the coil LI. The resonance frequency characteristic, that is, the resonance frequency F0 and the Q value are as follows.

F0 = 1 / (2π√ (LC)) Q = RS / (1 / 2πF0C)) where RS and L represent the resistance value of the selected resistor RI and the inductance value of the coil LI, respectively. And C represents the value of the combined capacitance in parallel with the inductance L by the varicap 44 or the like. √ (LC) is (L
C) represents the square root.

In the present embodiment, the varicap control voltage (VC voltage in FIG. 7) applied to the varicap diode 44 is controlled as shown in FIG. The reception characteristics are controlled in a wide range to a low range. In other words, when obtaining an echo signal on the short distance side, the varicap control voltage is increased, the value of the combined capacitance is reduced, the resonance frequency F0 is increased, the resolution is increased, and the echo signal on the long distance side is increased. Is obtained, the varicap control voltage is reduced, the value of the combined capacitance is increased, and the resonance frequency F0 is shifted to a lower side, so that a low-frequency side echo signal is received with high sensitivity.

FIGS. 8A and 8B are diagrams for explaining the operation of the receiving circuit 16. FIG. FIG. 8A shows a case where the composite piezoelectric body is driven by the transmission circuit 15 with a transmission waveform of, for example, 10 MHz and one cycle. The reception echo signal has a frequency band of 4 MHz to 20 MHz by the transmission circuit 16.

In the receiving circuit 16, in accordance with the band of the transmitting circuit, for example, at a short distance (region where propagation time is short), 10
~ 20 MHz, 4 in long distance (region where propagation time is large)
The reception band is varied according to the distance (propagation time), such as ８8 MHz.

That is, as shown in the frequency characteristic of reception on the right side of FIG. 8, when an echo signal on the short distance side is received, resonance occurs on the high frequency side as shown by the solid line, and In such a case, resonance is made to the lower frequency side, or characteristics as shown by a dotted line are obtained. The range is 4 to 20 MH of the received echo
The varicap control voltage and the selection of the coil LI and the resistor RI are controlled so as to change the range of z.

FIG. 8 (B) shows 10 MHz from the transmitting circuit.
The composite piezoelectric body is driven by a 1.5-cycle transmission waveform. The reception echo is 4 MHz to 16 depending on the transmission waveform.
It has a MHz band. The receiving circuit 16 matches the band of the transmitting circuit 15 and, for example, 8 to 16 MH at a short distance.
z, depending on the distance, such as 4-8 MHz for long distance,
Variable reception bandwidth.

However, the range is 4-16M of the received echo.
Control is performed so as to transition in the range of Hz. As described above, the frequency band of the receiving circuit 16 is varied according to the propagation time while keeping the frequency band of the ultrasonic pulse from the transmitting circuit 15 (within the frequency band), thereby suppressing the noise of the observation device as much as possible. , And S / N are improved.

Further, the transmission circuit 15 of FIG. 1 can receive a reception echo in a desired frequency band according to a user setting. For example, provided on the ultrasonic probe 2,
The frequency switching unit 18 can change the carrier frequency of the transmission circuit 15 to switch the band of the received echo between a high frequency and a low frequency.

The center frequency and the wave number of the transmission pulse of the transmission circuit 15 and the reception frequency characteristics (specifically, the resonance frequency and the Q value) of the reception circuit 16 are also provided on the ultrasonic observation apparatus 3 side, such as the frequency switching unit 18. A setting means or a selection setting means for variably controlling the change (shift characteristic) of the resonance frequency with respect to the propagation time may be provided.

Thus, an ultrasonic diagnostic image can be obtained with an arbitrary frequency characteristic desired by the user. For example, first emit an ultrasonic pulse with a wide frequency characteristic,
In this case, the receiving circuit 16 shifts the receiving frequency to the low frequency side by the propagation time and obtains the ultrasonic diagnostic image as described above, and then sets the desired region to S / N.

For example, the ultrasonic wave pulse is emitted at a high center frequency side with a large power while the band is narrow but the wave number is increased, and the receiving circuit 16 resonates at the center frequency to obtain an echo signal. Is performed a plurality of times while sequentially shifting the center frequency from a higher frequency to a lower frequency, thereby obtaining an ultrasonic diagnostic image with a better S / N in each region.

As described above, according to the ultrasonic diagnostic apparatus 1 of the present embodiment, a composite piezoelectric body having a wide frequency band is used, and the composite piezoelectric body is driven by a transmission pulse having an arbitrary frequency band. By receiving the received echo by the receiving circuit 16 having an appropriate frequency band with respect to the frequency band of the received echo, the overall characteristics can be obtained only by changing the characteristics of the transmitting circuit 15 and the receiving circuit 16 without changing the characteristics of the composite piezoelectric body. Can control the receiving frequency band. Therefore, if a frequency switch or the like is provided in the controller and the ultrasonic probe 2, the operator can freely select the frequency to be used. In addition, since one element of the composite piezoelectric element can cope with a plurality of frequencies, the outer diameter of the ultrasonic probe does not increase as in the related art, and can be reduced.

It should be noted that the present invention is not limited to the case of the ultrasonic probe 2 and the insertion portion 5 of the ultrasonic probe 2
Ultrasonic transducer 12 for obtaining an ultrasonic diagnostic image at the tip of the
In addition, an endoscopic function provided with an illumination window and an observation window, that is, an ultrasonic endoscope provided with means for optically illuminating an observation target such as an affected part and observing the illuminated observation target The same applies to the case of a mirror, and in that case, almost the same effect is obtained. For example, even in the case of an ultrasonic endoscope, since one element of the composite piezoelectric body can cope with a plurality of frequencies, the outer diameter of the ultrasonic endoscope does not become large and the diameter can be reduced as in the related art.

In the above description, the frequency characteristic of the ultrasonic pulse emitted from the transmitting circuit 15 can be variably controlled.
Also, the case has been described where the center frequency of the reception frequency and the like can be varied within the frequency band of the ultrasonic pulse emitted from the receiving circuit 16 side. In the frequency band of the ultrasonic pulse emitted in the variable the center frequency of the reception frequency and the like,
The present invention also includes a device which is resonated to a high frequency side in a shallow portion and has high resolution, and a deep portion is shifted so as to resonate in a low frequency side so that an echo signal up to a deep portion can be obtained with high sensitivity.

[Supplementary Notes] A composite consisting of a plurality of columnar piezoelectric bodies, which transmits an ultrasonic pulse into a sound field medium and receives reflected echoes from the sound field medium, and a resin filled between the piezoelectric bodies. In an ultrasonic diagnostic apparatus including an ultrasonic probe including a single ultrasonic transducer formed of a piezoelectric body and an ultrasonic observation device to which the ultrasonic probe can be connected,
A transmission circuit that excites the composite piezoelectric body and can arbitrarily change the frequency characteristics of the ultrasonic pulse, and the reception frequency band and the center frequency can be changed according to the frequency characteristics of the ultrasonic pulse and the propagation time of the ultrasonic pulse An ultrasonic diagnostic apparatus comprising: a receiving circuit; and a control unit capable of changing a frequency characteristic and a receiving frequency band of an ultrasonic pulse by the transmitting circuit.

[0062] 2. The control unit controls the transmission circuit to arbitrarily change the frequency band of the ultrasonic pulse within the response frequency band of the composite piezoelectric body, and the reception circuit controls the frequency band of the ultrasonic pulse and the ultrasonic pulse. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the reception frequency band can be shifted to a lower band within the frequency band of the ultrasonic pulse according to the propagation time. 3. The ultrasonic diagnostic apparatus according to claim 1, wherein the control unit is capable of controlling a frequency band of an ultrasonic pulse by the transmitting circuit and a receiving frequency band by a receiving circuit by control signals from an ultrasonic scope and an ultrasonic observation apparatus.

4. A composite consisting of a plurality of columnar piezoelectric bodies, which transmits an ultrasonic pulse into a sound field medium and receives reflected echoes from the sound field medium, and a resin filled between the piezoelectric bodies. In an ultrasonic diagnostic apparatus including an ultrasonic probe including a single ultrasonic transducer formed of a piezoelectric body and an ultrasonic observation apparatus to which the ultrasonic probe can be connected, a transmission pulse is applied to the composite piezoelectric body. A transmitting circuit that emits an ultrasonic pulse having a frequency characteristic in a wide frequency band, a receiving circuit capable of changing a receiving frequency band and a center frequency according to the frequency characteristic of the ultrasonic pulse and the propagation time of the ultrasonic pulse, An ultrasonic diagnostic apparatus, comprising: a control unit capable of changing a reception frequency band of the reception circuit. 5. 5. The ultrasonic diagnostic apparatus according to claim 4, wherein the control circuit allows the receiving circuit to shift a receiving frequency band to a lower frequency band within a frequency band of an ultrasonic pulse.

[0064]

As described above, according to the present invention, an electroacoustic transducer for transmitting an ultrasonic pulse into a sound field medium and receiving a reflected echo from the sound field medium is provided with a plurality of columnar piezoelectric transducers. An ultrasonic probe incorporating a single ultrasonic vibrator formed of a composite piezoelectric body composed of a resin and a resin filled between the piezoelectric bodies; and an ultrasonic observation device to which the ultrasonic probe can be connected. In the ultrasonic diagnostic apparatus, a transmitting circuit that excites the composite piezoelectric body and can arbitrarily change the frequency characteristic of the ultrasonic pulse, and a receiving frequency according to the frequency characteristic of the ultrasonic pulse and the propagation time of the ultrasonic pulse. Since it has a receiving circuit that can change the band and the center frequency, and a control unit that can change the frequency characteristics and the receiving frequency band of the ultrasonic pulse by the transmitting circuit, the receiving frequency band and the receiving frequency band can be changed according to the propagation time. By changing the center frequency and the like, for example, in a deep part where the propagation time is large, a reception frequency band is set on the low frequency side, and the deep part can be received with high sensitivity to obtain an ultrasonic diagnostic image suitable for a diagnostic part. The ultrasonic probe can be reduced in diameter by two ultrasonic transducers.

The control unit controls the transmitting circuit to arbitrarily change the frequency band of the ultrasonic pulse within the response frequency band of the composite piezoelectric body, and the receiving circuit controls the frequency band of the ultrasonic pulse. And, according to the propagation time of the ultrasonic pulse, the reception frequency band can be shifted to a low frequency within the frequency band of the ultrasonic pulse. In a deep part where the propagation time is long, a reception frequency band is set on the low frequency side, and the deep part is received with high sensitivity to obtain an ultrasonic diagnostic image suitable for a diagnostic part.

The control section can control the frequency band of the ultrasonic pulse by the transmitting circuit and the receiving frequency band by the receiving circuit by the control signals from the ultrasonic scope and the ultrasonic observation device, thereby controlling the ultrasonic wave. The characteristics and the like of the ultrasonic diagnostic image obtained by the composite piezoelectric body from a scope or the like can be controlled.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a composite piezoelectric body constituting an ultrasonic transducer provided at a tip of an ultrasonic probe.

FIG. 3 is a diagram showing characteristics of a composite piezoelectric body according to the present embodiment, such as an impulse response, in comparison with a conventional example.

FIG. 4 is a circuit diagram illustrating a configuration of a transmission circuit.

FIG. 5 is a diagram showing a frequency band and power in the case of transmission pulses having different wave numbers.

FIG. 6 is a circuit diagram illustrating a configuration of a receiving circuit.

FIG. 7 is a diagram showing a voltage applied to a varicap diode with respect to time.

FIG. 8 is an explanatory diagram of the operation of the receiving circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultrasonic diagnostic apparatus 2 ... Ultrasonic probe 3 ... Ultrasonic observation apparatus 4 ... Monitor 5 ... Insertion part 6 ... Operation part 8 ... Connector 11 ... Flexible shaft 12 ... Ultrasonic vibrator 15 ... Transmission circuit 16 ... Receiving circuit 17 ... Signal processing circuit 18 ... Frequency switching unit 19 ... Control unit 21 ... Piezoelectric body 22 ... Resin 31 ... Trigger generator 33a, 33b ... FET 34 ... Pulse transformer 41 ... Amplifier 42,43 ... Changeover switch 44 ... Variable capacitance (varicap) Diode) 45 ... Controller

Claims (3)

[Claims] 1. An electroacoustic transducer for transmitting an ultrasonic pulse into a sound field medium and receiving a reflected echo from the sound field medium is composed of a plurality of columnar piezoelectric bodies, and is filled between the piezoelectric bodies. An ultrasonic diagnostic apparatus comprising: an ultrasonic probe including one ultrasonic transducer formed of a composite piezoelectric body made of resin; and an ultrasonic observation apparatus to which the ultrasonic probe can be connected. A transmission circuit that excites and can arbitrarily change the frequency characteristics of the ultrasonic pulse; and a reception circuit that can change the reception frequency band and the center frequency according to the frequency characteristics of the ultrasonic pulse and the propagation time of the ultrasonic pulse. An ultrasonic diagnostic apparatus comprising: a control unit capable of changing a frequency characteristic of an ultrasonic pulse and a reception frequency band by the transmission circuit. 2. The control unit controls the transmission circuit to arbitrarily vary the frequency band of the ultrasonic pulse within the response frequency band of the composite piezoelectric body, and the reception circuit controls the frequency band of the ultrasonic pulse. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the reception frequency band can be shifted to a low frequency within the frequency band of the ultrasonic pulse according to the propagation time of the ultrasonic pulse. 3. The control unit according to claim 1, wherein a frequency band of the ultrasonic pulse by the transmission circuit and a frequency band of the reception pulse by the reception circuit can be controlled by a control signal from an ultrasonic scope and an ultrasonic observation device. Ultrasound diagnostic equipment.