JP2000342583A - Ultrasonic probe and ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic probe and an ultrasonic diagnostic device suitable for obtaining an ultrasonic image suppressing a side lobe in a wide range by transmission/reception by single pulse driving. SOLUTION: In this diagnostic device, an ultrasonic probe 11 is obtained by providing a ground electrode on the ultrasonic radiating surface of a piezoelectric oscillator 2 which is nearly in the shape of a rotationally symmetric disk with a smaller thickness at its center part and a larger thickness at is peripheral part and providing a signal electrode part 4 at its center part and electrode patterns 5a to 5d obtained by equally dividing a signal electrode part at its peripheral part in a peripheral direction on the rear surface of the oscillator 2. The obtained probe 11 is connected to an ultrasonic observing device 22. A high-frequency driving pulse and a low-frequency driving pulse are respectively and simultaneously applied to the part 4 and the patterns 5a to 5d at the peripheral part, and an ultrasonic image of a satisfactory image quality which is high in resolution by high-frequency components in a short distance area and is satisfactory in transmitting properties by low-frequency components in a long distance area is constructed through an amplifier 28, or the like, with respect to echo signals obtained by respectively receiving ultrasonic waves reflected by the side of a living body and converting them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ultrasonic probe and an ultrasonic diagnostic apparatus for transmitting and receiving ultrasonic waves to obtain an ultrasonic image.

[0002]

2. Description of the Related Art A conventional ultrasonic probe has a concave spherical surface of a radiation surface of a vibrator so as to have a geometrical focus on a central axis, or a geometrical focus on a central axis of a vibrator. And a focusing acoustic lens having

However, in such an ultrasonic probe, the beam width is narrowed in the vicinity of the focal point of the ultrasonic beam, but the ultrasonic beam spreads out of the focal point, so that the resolution is high over a wide range. No image could be obtained.

One of the methods to solve this problem is as follows.
Japanese Patent Laying-Open No. 51-60491 discloses an ultrasonic probe that “forms an effective and virtual annular sound source in front of or behind an ultrasonic probe, respectively”. Japanese Patent Application Laid-Open No. 10-322798 discloses an ultrasonic probe in which the vibration amplitude is weighted in order to suppress the side lobe of the ultrasonic probe forming the virtual annular sound source.

In order to improve the near-field beam characteristics, Japanese Patent Publication No. 4-14014 discloses a dual aperture ultrasonic transducer (see FIG. 1) which is divided into a central area and an annular area so that each area can be selectively driven. Tentacles) are disclosed.

[0006]

SUMMARY OF THE INVENTION In the case of an ultrasonic probe forming a virtual annular sound source or a probe having a conical surface-shaped ultrasonic radiation surface, the ultrasonic radiation surface at a position near the central axis of the transducer is preferred. Is directed to the near field, and the sound axis of the ultrasonic wave radiated from this part crosses the center axis of the vibrator in the near field, and then moves away from the center axis as it goes far. On the other hand, the sound axis of the ultrasonic wave radiated from the ultrasonic wave radiating surface region located far from the central axis of the vibrator intersects with the central axis of the vibrator in a far field.

[0007] Japanese Patent Application Laid-Open No. 51-60491 discloses a conventional "effective and virtual circle in front of or behind an ultrasonic probe, respectively, in which ultrasonic pulses having the same frequency component are radiated from the entire surface. The ultrasonic probe that forms an annular sound source provided a narrow main beam over a wide area, but in the near field, the sound field was disturbed by the effect of the acoustic radiation surface far from the center axis of the transducer. In the far field, the influence of the side lobe is large, which causes deterioration of the ultrasonic image.

Therefore, in order to reduce side lobes in the far field, Japanese Patent Application Laid-Open No. H10-322798 discloses an ultrasonic wave that “forms an effective and virtual toroidal sound source in front of or behind an ultrasonic probe, respectively”. In the probe, the vibration amplitude was weighted in the radial direction of the transducer. However, an ultrasonic probe that weights the vibration amplitude to form a virtual annular sound source with suppressed side lobes can form a beam with a narrow beam width over a wide range and suppress the side lobes. However, the sound pressure on the central axis at a distant place becomes small, and it is difficult to improve the depth.

In order to reduce the influence of the near-field sound field disturbance, Japanese Unexamined Patent Publication (Kokai) No. 4-14014 discloses a method in which a vibrator is used in a probe having an ultrasonic effective radiation surface having an arc surface symmetric with respect to an axis. A probe is disclosed which can be selectively driven into a central region and an annular region.In this method, a region to be driven in near field and far field is selectively determined as a central region or an annular region. Therefore, it is not possible to obtain an ultrasonic image with good image quality from near field to far field by transmission / reception by one pulse drive.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and forms a narrow beam over a wide range by a single pulse drive, and reduces the side pressure without lowering the sound pressure in a distant place. It is an object of the present invention to provide an ultrasonic probe capable of suppressing a lobe.

It is another object of the present invention to provide an ultrasonic diagnostic apparatus capable of obtaining an ultrasonic image with high image quality over a wide range by transmitting and receiving by one pulse drive by employing the ultrasonic probe. .

[0012]

Means for Solving the Problems A first circular ultrasonic vibrating section, a first signal electrode section provided on the first ultrasonic vibrating section, and an outer side of the first ultrasonic vibrating section. A second ultrasonic vibrating part having a structure thicker than the thickness of the first ultrasonic vibrating part, and a second signal electrode part provided on the second ultrasonic vibrating part, , The acoustic radiation surface of the second ultrasonic vibrating portion, or the first ultrasonic vibrating portion and the second ultrasonic vibrating portion have an ultrasonic radiation surface of a virtual annular or substantially conical surface shape. By forming an ultrasonic probe, a high-frequency drive pulse is applied to the first signal electrode portion and a low-frequency drive pulse is applied to the second signal electrode portion at a time, thereby forming a narrow beam over a wide range. Transmits ultrasonic waves that form and increase the sound pressure at distant places and suppress sidelobes It was to function.

A first ultrasonic vibrating portion having a circular shape, a first signal electrode portion provided on the first ultrasonic vibrating portion, and a concentric circular shape provided outside the first ultrasonic vibrating portion. A second ultrasonic vibration part having a structure thicker than the thickness of the first ultrasonic vibration part, and a second signal electrode part provided in the second ultrasonic vibration part, An ultrasonic probe having an acoustic radiation surface of a second ultrasonic vibrating portion, or an ultrasonic probe in which the first ultrasonic vibrating portion and the second ultrasonic vibrating portion have an ultrasonic radiation surface of a virtual annular or substantially conical surface shape. And a filter means for separating an echo signal from the ultrasonic probe by a frequency component, and a low frequency component obtained by the filter means to obtain an image of an observation target far from the ultrasonic probe. Used, the image of the observation target close to the ultrasonic probe is applied to the filter means. The ultrasonic diagnostic apparatus using the high frequency component obtained by the above-described method can provide a high-resolution ultrasonic image with a high frequency component for a near observation target, and an S image with a low-frequency component with good transparency for a distant observation target. /
Ultrasonic images with good N are obtained, so that an ultrasonic image with good image quality can be obtained comprehensively over a wide area.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 to 5 relate to a first embodiment of the present invention, and FIG. 1 shows an outline of features and the like of an ultrasonic probe according to the first embodiment of the present invention. FIG. 2 shows an ultrasonic probe according to the first embodiment of the present invention, and FIG. 3 shows an overall configuration of an ultrasonic diagnostic apparatus configured by using the first embodiment of the present invention. FIGS. 4A and 4B show characteristics of the amplifier and the dynamic filter used in the present embodiment, respectively, and FIG. 5 shows a configuration of a modified ultrasonic probe.

Prior to concrete description of the first embodiment of the present invention, first, referring to FIG. 1, the general characteristics of the ultrasonic probe according to the first embodiment of the present invention and the signal processing means will be described. Main functions and the like will be described. The piezoelectric vibrator constituting the ultrasonic probe according to the present invention is formed such that the center portion is thinner and thicker in the radial direction. Although the piezoelectric vibrator used in the present invention may be made of piezoelectric ceramics, it is more preferable that the piezoelectric vibrator is a composite piezoelectric body in which micro piezoelectric elements are embedded in resin. The piezoelectric vibrator emits an ultrasonic wave containing a large amount of high frequency components from a center portion, and emits an ultrasonic wave containing a large amount of low frequency components toward an outer periphery.

As shown in FIG. 1A, a near-field (close observation object) ultrasonic image mainly uses high-frequency components of ultrasonic waves transmitted and received at the center of a piezoelectric vibrator indicated by hatched portions. Therefore, it is possible to construct a high-resolution image which is a feature of high-frequency ultrasonic waves without deterioration of an image due to disturbance of a sound field in a near field.

Since an ultrasonic component for constructing an ultrasonic image of a distant field (a distant observation target) uses a low-frequency component having a small attenuation in a living body, an echo signal from a distant field can be received with a sufficient magnitude. Image can be constructed to a deep place. In addition, the main radiation surface that emits the ultrasonic wave of the low-frequency component forms an annular radiation surface that forms a virtual annular sound source or an annular radiation surface having a conical surface shape. Thus, a narrow main lobe beam can be formed over a wide range. For reference, the beam characteristics of the conventional single focus probe are indicated by dotted lines.

Further, a plurality of wave receiving portions A and B are arranged symmetrically in the direction of rotation of the central axis of the piezoelectric vibrator, and echo signals from the narrow main lobe are simultaneously received by the wave receiving portions A and B. However, the echo signals from the side lobes are received only at the same time (at the observation device side), taking advantage of the fact that sound path differences occur in each of the receiving sections and the time is delayed and received. By performing the extraction image processing, the influence of the side lobe of the ultrasonic image in the far field is suppressed.

As shown in FIG. 1B, when the receiving units A and B are arranged, the echoes from the reflector a on the main lobe and the reflector b on the side lobes are received at the receiving units A and B. FIGS. 1C and 1D show waveforms obtained by multiplying a received signal and a received signal from each of the receiving units A and B as one of means for extracting only an echo signal received simultaneously by each of the receiving units A and B. ).
When multiplying each reception signal by each of the wave receiving units A and B, it is preferable to multiply the pulse waveforms by each other to multiply the envelope signal indicated by a dotted line because adjustment and the like are easy.

In the present invention, the main radiating surface for radiating ultrasonic waves of low frequency components forming a far-field beam is a circular radiating surface forming a virtual circular sound source or a circular radiating surface having a conical surface shape. Therefore, as shown in FIG. 1E, since the separation of the main lobe and the side lobe is better than that of the conventional single focus probe, the separation of the echo signal from the main lobe and the echo signal from the side lobe are also conventional. It is better than a single focus probe.

It is preferable that the distance between the wave receiving portions A and B from the central axis of the vibrator is larger, and it is preferable that three or more wave receiving portions A and B are provided at equal intervals. Further, the wave receiving units A and B may be common to the ultrasonic wave transmitting unit, or may be provided exclusively for wave receiving.

Hereinafter, a detailed configuration of the ultrasonic probe 1 and the like according to the first embodiment of the present invention will be described. FIG. 2A shows an ultrasonic probe 1 according to the first embodiment of the present invention. The ultrasonic probe 1 has a piezoelectric vibrator 2 having a rotationally symmetrical substantially disk shape, more specifically, one surface is a flat flat surface, and the other surface is polished to a substantially conical shape, and the center portion is the thinnest. The ground electrode 3 is provided on the entire surface of the substantially conical curved surface serving as the ultrasonic wave emitting surface (also referred to as the front surface) of the piezoelectric vibrator 2, and concentrically on the other flat surface (also referred to as the rear surface or the back surface). Two divided signal electrode units 4 and 5 are provided.

The apex of the substantially conical curved surface of the piezoelectric vibrator 2 has a substantially spherical shape for easy processing. FIG. 2 (B)
As shown in (1), the signal electrode portion 5 of the piezoelectric vibrator 2 is composed of signal electrode patterns 5a, 5b, 5c, and 5d divided symmetrically in the rotation direction of the central axis of the piezoelectric vibrator 2, for example.

The piezoelectric vibrator 2 provided with the signal electrodes 4 and 5 as described above has a notch 8 provided in a ring shape on the front inner surface of an insulating member 7 bonded in a ring shape to the inner surface of a metal case 6. The piezoelectric vibrator 2 is inserted and fixed with its rear surface on which the signal electrodes 4 and 5 are formed facing inward.
The ground connection line 9 is soldered to the ground electrode 3 and the metal case 6 on the front surface of the first embodiment.

On the front surface (upper surface) of the ground electrode 3 of the piezoelectric vibrator 2, using an adhesive (for example, epoxy resin),
The acoustic matching layer 10 is formed using a mold (not shown) so that the thickness of the ultrasonic frequency used for ultrasonic radiation is λ depending on the thickness of the piezoelectric vibrator 2 at each portion, and the thickness is λ / 4. I have. In the present embodiment, only one acoustic matching layer 10 is provided, but two or more acoustic matching layers 10 can be provided to increase the transmission / reception efficiency.

From the back of the metal case 6, the signal electrode 4 of the piezoelectric vibrator 2 and the signal electrode patterns 5a, 5b, 5c, 5d
Respectively, signal lines 11, 12a, 12b, 12c, 12
The backing layer 13 is formed by soldering d, pouring in, for example, an epoxy resin as an adhesive mixed with a member having a high function of absorbing and attenuating sound (for example, ferrite rubber), and curing.

A ground wire 14 is soldered to the metal case 6, and the ground wire 14 and the ground electrode 3 of the piezoelectric vibrator 2 are connected to the metal case 6 and the ground connection wire 9.
Are electrically connected via Signal lines 11, 12a, 1
The 2b, 12c, 12d and the ground line 14 are connected to the observation device 22 as shown in FIG.

The metal case 6 is connected to a rotation drive mechanism (not shown). At least the front surface of the acoustic matching layer 10 of the ultrasonic probe 1 is coated with a chemical-resistant and water-resistant parylene (polyparaxylene). A film (not shown) is formed to protect the inside.

As will be described below, with respect to the ultrasonic probe 1 having such a configuration, a high-frequency driving pulse is applied to the central signal electrode portion 4 and a low-frequency driving pulse is applied to the peripheral signal electrode portion 5. By applying a driving pulse of a frequency at a time and transmitting ultrasonic waves to the observation target side, an ultrasonic beam having good characteristics having the sound pressure distribution and the like shown in FIG. The high frequency component and the low frequency component are separated from the echo signal generated by receiving the reflected ultrasonic wave reflected by the By multiplying means for emphasizing and extracting the phase component, it is possible to obtain an ultrasonic image with a good depth in a distant region, and to obtain an ultrasonic image with a good resolution by a high frequency component in a near region. I have.

FIG. 3 shows an ultrasonic probe 1 according to the first embodiment.
1 shows a configuration of an ultrasonic diagnostic apparatus 21 using a. In the ultrasonic diagnostic apparatus 21, the ultrasonic probe 1 is connected to the ultrasonic probe 1, and a driving pulse (transmission pulse) is applied to the ultrasonic probe 1 so that an ultrasonic wave is observed. An observation device 22 that transmits a wave to the living body as an object, receives reflected ultrasonic waves reflected by the living body, and performs signal processing on an echo signal converted into an electric signal, and an output from the observation device 22 A monitor 23 displays a corresponding ultrasonic image when a video signal is input. In FIG. 3, the ultrasonic probe 1 includes a piezoelectric vibrator 2 and its signal electrode 5.
Only the configuration in the vicinity is shown.

The observation device 22 has a high-frequency pulser 24 and a low-frequency pulser 25 that generate driving pulses of the most suitable frequency for the signal electrodes 4 and 5, that is, high-frequency and low-frequency driving pulses. / Echo switches 26, 27a, 27b, 27c, 27d and the pulse / echo switches 26, 27a, 27b, 27c, 27d
Signal lines 11, 12a, 12b, 12 connected to
Pulse signals are supplied to the signal electrode 4 and the signal electrode patterns 5a, 5b, 5c, 5d via c and 12d, respectively.

The pulse / echo switches 26 and 27
a, 27b, 27c, and 27d can be switched between a pulse signal side and an echo signal side by a switching signal from a controller (not shown). That is, when driving pulses are output from the low-frequency pulsar 24 and the high-frequency pulsar 25 at one time, each driving pulse is output from the signal lines 11, 12a, 12b, 12c,
The signal is transmitted to the ultrasonic probe 1 via 12d.

A reflected ultrasonic wave reflected at a portion where the acoustic impedance inside the living body as an object to be observed changes is converted into an electric signal, that is, an echo signal by the ultrasonic probe 1, and the echo signal is converted to the signal line. 11, 12a, 12
The pulses / echo switches 26, 27a, 27b, 27c, 27d are input to the pulse / echo switches 26, 12c, 12d.
Pulse / echo switches 26, 27a, 27b, 27c,
27d is switched by a switching signal from a controller (not shown) when an echo signal is input, so that the echo signals transmitted via the signal lines 11, 12a, 12b, 12c, 12d are amplified by amplifiers 28, 29a, respectively.
29b, 29c, 29d and dynamic filter 3
0, 31a, 31b, 31c, and 31d are sequentially input.

FIGS. 4A and 4B show the amplifiers 28, 29a, 29b, 29c and 29d and the dynamic filters 30, 31a, 31b and 31c used in the present embodiment.
31d shows the respective characteristics.

The amplifier 28 is set to have a characteristic C28 for amplifying only a near-field (a short-distance region where the distance from the ultrasonic probe 1 is small) region. In other words, the characteristic C2 has a large gain with respect to an echo signal from a small area in the lapse of time after the pulse application, and has a small gain after a time corresponding to a short distance area.
8 is set. The echo signal amplified by the amplifier 28 is input to a dynamic filter 30 capable of dynamically changing the filter characteristics.

The dynamic filter 30 has the configuration shown in FIG.
As shown in (B), the characteristic C30 has a filter characteristic of transmitting only the high frequency component of the echo signal, and the high frequency component of the echo signal passed through the dynamic filter 30 is input to the A / D converter 32a.

On the other hand, amplifiers 29a, 29b, 29
c and 29d are characteristics C2 for amplifying only the far-field echo signal.
9 is set. In other words, a small gain is applied to an echo signal from a near field or a near field in the elapse of time after pulse application, and an echo signal from a far field (far field) after the near field is obtained. In this case, the characteristic C29 is set to a large gain. The echo signals amplified by the amplifiers 29a, 29b, 29c, and 29d are input to dynamic filters 31a, 31b, 31c, and 31d that can dynamically change the filter characteristics.

Dynamic filters 31a, 31b, 3
1c and 31d have their characteristics C31 as shown in FIG.
Are sequentially shifted from those shown by solid lines to those shown by dotted lines according to the time at which the echo signal returns. That is, according to the time when the echo signal returns, the band pass width of the filter is sequentially shifted to the low frequency side so that the farther the echo signal, the lower the frequency component signal passes. The transmission characteristic of the echo signal that returns from a relatively near field is set to a lower frequency than that of the dynamic filter 30.

The dynamic filters 31a, 31
The echo signals passed through 1b, 31c and 31d are input to a four-input multiplier 33 shown in FIG. 3, where the signals having the same phase are amplified by multiplication and sent to an A / D converter 32b. This multiplier 3
As shown in FIGS. 1 (C) and 1 (D), in the signal processed in step 3, signals input in the same phase are amplified, but signals input out of phase are reduced in width. The signal input in phase can be emphasized (in FIG. 1, the receiving units A,
B, in the first embodiment, the wave receiving portions A and B correspond to the signal electrode patterns 5a and 5d or 5b and 5c.
)).

Each signal digitized by each of the A / D converters 32a and 32b is input to an adder 34 (as means for synthesizing both images) and added, and the added signal is sent to an image processing circuit 35. After being input and subjected to image processing for converting it into a video signal, it is output to the monitor 23,
The ultrasonic observation image is displayed on the display surface of.

In this embodiment, the A / D converter 32a,
Each signal digitized at 32b is subjected to addition processing at the adder 34, but the analog signal may be digitized after being added at the adder 34, or the amplifiers 28, 29a, 2
9b, 29c and 29d simply amplify the echo signal,
When the adder 34 adds the signals digitized by the A / D converters 32a and 32b, the A / D converters 32a and 32b
An image may be constructed by using a signal obtained by performing an addition process while changing the weight of the digital signal from 32b.

In this embodiment, the echo signal is amplified and converted into a signal of a desired band through a band-pass filter and processed by the multiplier 33. Before the signal is input to the multiplier 33, as shown in FIG. After conversion into an envelope signal as shown by a dotted line or the like, the signal may be processed by the multiplier 33.

In the present embodiment, the signal electrode section 5 divides the electrode pattern into electrode patterns 5a, 5b, 5c, and 5d, and the echo signal received by the vibrator section having each of the electrode patterns 5a, 5b, 5c, and 5d. Is used to perform signal processing for reducing side lobes in the far field, but an ultrasonic probe 1 'shown in FIG. 5 may be used. FIG. 5A is a sectional view showing the structure of an ultrasonic probe 1 ′ according to a modification, and FIG. 5B is a view of the ultrasonic probe 1 ′ as viewed from the front.

In the ultrasonic probe 1 'shown in FIG. 5, the receivers 37a, 37b, 37c, 3 made of a polymer piezoelectric element exclusively for receiving waves are used.
7d is arranged at a position symmetrical with respect to the center axis of the piezoelectric vibrator 2 for transmitting and receiving the piezoelectric vibrator 2 and connected to the signal lines 12a ', 12b', 12c ', and 12d', respectively. The echo signals reflected from the far field are received by the receivers 37a, 37b, 37c, and 37d and input to the amplifiers 29a, 29b, 29c, and 29d in FIG. 3, respectively. , It is also possible to reduce the effect of the echo signal from the side lobe in the far field.

The signal electrode 5 on the back side of the piezoelectric element 2
Electrode patterns 5a, 5b, 5c, 5d
a, 12b, 12c, 12d, a low-frequency pulsar 25
And transmits low frequency ultrasonic waves. The signal electrode unit 4 on the center side transmits high-frequency ultrasonic waves from the high-frequency pulsar 24 and receives reflected ultrasonic waves from the living body side in the same manner as in the first embodiment.

According to the present embodiment (and its modified example), an ultrasonic image having a high resolution in the near field is mainly formed by using the high frequency components of the ultrasonic waves transmitted and received at the center of the piezoelectric vibrator 2. The ultrasound image of the far-field is mainly composed of low-frequency ultrasonic waves radiated from an annular radiating surface or a conical annular radiating surface forming a virtual annular sound source with small attenuation in a living body. And transmitting / receiving sections or receivers 37a, 37 formed by electrode patterns 5a, 5b, 5c, 5d arranged at positions symmetrical with respect to the rotational direction of the central axis of the vibrator.
By integrating the signals received at b, 37c and 37d, the echo signal from the narrow main lobe radiated from the radiation surface can be image-processed while being distinguished from the echo signal from the side lobe over a wide range. A good ultrasonic image can be constructed, and therefore an ultrasonic image with good image quality can be obtained comprehensively from near field to far field. Although the thickness of the piezoelectric vibrator 2 is continuously increased from the center to the periphery in FIG. 2, the thickness may be increased stepwise.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention.
1 shows an ultrasonic probe 41 according to the embodiment. FIG. 6A shows a cross-sectional structure of the ultrasonic probe 41, FIG. 6B shows an electrode on the back surface of the composite piezoelectric vibrator, and FIG. 6C shows the ultrasonic probe viewed from the back surface. 41 is shown. The ultrasonic probe 41 of the present embodiment has a plurality of micro piezoelectric elements embedded in an epoxy resin as shown in FIG. 6 (A) (in FIG. 6 (A), the white portion represents the epoxy resin, and the hatched portion represents the epoxy resin). A composite piezoelectric vibrator 42 (each showing a micro piezoelectric element) is used.

The composite piezoelectric vibrator 42 has a thin central portion and a thick peripheral portion, and is formed into a conical surface or a concave spherical shape concave toward the ultrasonic wave emitting surface side. 6B, the ground electrode 43 is provided over the entire surface, and the other surface is equidistant with respect to the central axis of the composite piezoelectric vibrator 42 and the two signal electrode portions 44 and 45 divided concentrically as shown in FIG. , The receiving-only electrodes 46a, 46b, 46 so that the three receiving parts are positioned at equal intervals.
b, 46c are provided.

The ferrite rubber backing material 48 is an imaginary circle having an inner circular portion 49 of a concave spherical surface and a locus surface obtained by rotating a circular arc having a center not on the central axis of the vibrator symmetrically about the central axis of the vibrator. It has a front surface 51 having a curved outer circular portion 50 forming a ring sound source, and has a shape in which the rear surface side of the composite piezoelectric vibrator 42 fits into the front surface 51.

The ground line 1 is provided on the front surface 51.
4, the signal lines 11 and 12 for the signal electrode units 44 and 45 and the reception line 52 for the wave receiving electrode units 46a, 46b and 46c.
through holes 53a, 53b, 53 for guiding a, 52b, 52c to the back of the ferrite rubber backing material 48.
c, 53d, 53e and 53f are provided as shown in FIG. 6 (C).

The ferrite rubber backing material 48 is adhered to the inner surface of the stainless steel case 6, and the signal electrodes 44, 45 and the signal receiving electrodes 46a, 46b, 46c of the composite piezoelectric vibrator 42 are respectively supplied with signals. Lines 11, 12
After connecting the receiving lines 52a, 52b, 52c with a conductive adhesive, the signal lines 11, 12 and the receiving lines 52a, 52b are inserted into the through holes 53a, 53b, 57c, 57d, 53e of the ferrite rubber backing material 48. , 52c
Then, the composite piezoelectric vibrator 42 is adhered to the front surface of the ferrite rubber backing material 48 using an epoxy adhesive.

Thereafter, the ground wire 1 is passed through the through hole 53f from the back of the ferrite rubber backing material 48.
4 is guided to the front surface of the composite piezoelectric vibrator 42 and is adhered and fixed with a conductive adhesive.

The acoustic matching layer 54 fixed to the front surface 42a of the composite piezoelectric vibrator 42 has the same shape as the front surface 42 of the composite piezoelectric vibrator 42 after one surface is bonded to the ferrite rubber backing material 48 in advance. The thickness is formed over the entire surface of the composite piezoelectric vibrator 42 so as to have a thickness of λ / 4, where λ is the wavelength of the center frequency of the ultrasonic wave transmitted and received in the minute area of the composite piezoelectric vibrator 42 immediately below. Then, the composite piezoelectric vibrator 42 is bonded to the front surface 42a using an adhesive made of epoxy resin.

The through holes 53a, 53b, 53c, 53d, 53e, 53 of the ferrite rubber backing material 48
After the epoxy resin mixed with ferrite rubber is poured into the f and cured, the back surface of the metal case 6 is closed by bonding a metal cover (not shown), and the entire surface of the ultrasonic probe 41 is covered with the above-described parylene. Coaching (not shown)
And then attached to a rotary drive mechanism (not shown).

The ground line 14, the signal lines 11, 12 and the receiving lines 52a, 52b, 52c are connected to an observation device (not shown), subjected to signal processing similar to that shown in the first embodiment, and subjected to ultrasonic waves. Get an image.

In the present embodiment, the electrode on the signal electrode side of the composite piezoelectric vibrator 42 is constituted by the two signal electrode portions 44 and 45 and the three receiving-only electrode portions 46a, 46b and 46c. The number of the portions may be three or more. Alternatively, as shown in FIG. 2, some of the signal electrode portions 5 may be circumferentially arranged around the central axis of the vibrator without providing the receiving-only electrode portion. A low-frequency wave transmitting / receiving unit may be configured by the electrode patterns 5a, 5b, 5c, and 5d for dividing into symmetrical positions and obtaining a far-field ultrasonic image.

According to the ultrasonic probe 41 of the present embodiment, the high frequency component of the ultrasonic wave is transmitted and received from the center of the composite piezoelectric vibrator 42, and the low frequency component of the ultrasonic wave is transmitted and received in the circumferential direction. Waved. Since the near-field ultrasonic image is constructed using the high-frequency components of the ultrasonic waves, the effective diameter of the transmitting and receiving transducer is small, so the near-field sound field is derived from the fact that the effective diameter of the transmitting and receiving transducer is too large. The image quality of a near-field ultrasonic image can be improved without causing disturbance of the image.

The far-field ultrasonic image is mainly composed of low-frequency components radiated from an annular radiating surface or a conical annular radiating surface forming a virtual annular sound source with small attenuation in a living body. Dedicated receiving electrodes 46a, 46b, 4 arranged at positions symmetrical to the vibrator in the direction of rotation of the central axis using ultrasonic waves.
Wave receiving portion or electrode pattern 5 formed by 6c
a, 5b, 5c, and 5d integrate the signals received by the transmission / reception unit to distinguish the echo signals from the narrow main lobe and the echo signals from the side lobes over a wide range radiated from the radiation surface. Since image processing can be performed, high-resolution images can be obtained from near field to far field.

According to the present embodiment, the composite piezoelectric vibrator 4
2 enables efficient transmission and reception of a broadband pulse having a desired center frequency at each part of the vibrator, so that the sensitivity is improved as compared with the case of using a piezoelectric ceramic vibrator, and each signal is improved. Since the crosstalk between the electrodes can be reduced, the image quality is also improved.

[Supplementary Notes] A circular first ultrasonic vibrating section, a first signal electrode section provided on the first ultrasonic vibrating section, and a concentric circular outer side of the first ultrasonic vibrating section. A second ultrasonic vibrating part having a structure thicker than a thickness of the first ultrasonic vibrating part; and a second signal electrode part provided in the second ultrasonic vibrating part. An ultrasonic wave radiating surface of the ultrasonic wave vibrating portion, or the first ultrasonic vibrating portion and the second ultrasonic vibrating portion each have a virtual annular or substantially conical ultrasonic wave radiating surface. Tentacles.

[0061] 2. The first and second ultrasonic vibrators are configured such that an ultrasonic vibrator or a group of ultrasonic vibrators having a structure continuously or stepwise thicker than a center and a center of the ultrasonic vibrator or the ultrasonic vibrator group 2. A circular first signal electrode portion provided in the portion, and a second signal electrode portion provided concentrically outside the first signal electrode portion. Ultrasonic probe.

3. A circular first ultrasonic vibrating section, a first signal electrode section provided on the first ultrasonic vibrating section, and a concentric circular outer side of the first ultrasonic vibrating section.
A second ultrasonic vibrating part having a structure thicker than the first ultrasonic vibrating part, and a second signal electrode part provided in the second ultrasonic vibrating part; An acoustic radiation surface of an ultrasonic vibrating section, or an ultrasonic probe in which the first ultrasonic vibrating section and the second ultrasonic vibrating section have a virtual annular or substantially conical ultrasonic emitting surface, Filter means for separating the echo signal from the ultrasonic probe by a frequency component, using a low frequency component obtained by the filter means to obtain an image of an observation target far from the ultrasonic probe. An ultrasonic diagnostic apparatus, wherein an image of an observation target close to the ultrasonic probe uses a high frequency component obtained by the filter means.

4. A ground electrode provided on the surface of the vibrator of the first and second ultrasonic vibrating portions; and a quarter of a wavelength of a frequency dependent on the thickness of the vibrator provided on the surface of the ground electrode. 3. The ultrasonic probe according to claim 1, wherein an acoustic matching layer having a thickness is provided.

5. An additional feature, comprising: two or more ultrasonic receiving units, ultrasonic transmitting / receiving units, or ultrasonic transmitting / receiving units provided at equal intervals on the same circumference from the center axis of the ultrasonic transducer. 5. The ultrasonic probe according to 1, 2, or 4.

6. In the case of an ultrasonic probe that forms a virtual annular sound source (virtual annular probe) or an ultrasonic probe that has a conical ultrasonic emission surface, the thickness of the ultrasonic transducer is set to An ultrasonic probe characterized in that the signal electrode portion is divided into two or more concentrically with respect to the center axis of the ultrasonic transducer, the thickness being increased as the distance from the center increases. 7. The image of the part far from the ultrasonic probe is constructed using the lower frequency component of the echo signal as compared with the image of the part near the ultrasonic probe. Ultrasonic diagnostic equipment.

8. In an ultrasonic probe that forms a virtual toroidal sound source (virtual toroidal probe) or an ultrasonic probe that has a conical ultrasonic emission surface, move the thickness of the transducer away from the center of the transducer. And the signal electrode portion is divided into two or more concentrically with respect to the central axis of the vibrator, and at least two ultrasonic transmission / receptions are symmetrical with respect to the rotational direction of the vibrator axis. An ultrasonic probe comprising a wave portion or an ultrasonic wave receiving portion. (Function and Effect of Supplementary Note 8) By constructing an image using signals transmitted and received by the ultrasonic wave transmitting / receiving unit or the ultrasonic wave receiving unit at the same time, the influence of side lobes in the far field is suppressed.

9. The image of the part far from the ultrasonic probe is constructed using a low frequency component of an echo signal as compared with the image of the part close to the ultrasonic probe, and the echo from the part far from the ultrasonic probe. Image processing is performed using only signals that are received simultaneously by at least two or more ultrasonic transmitting / receiving units or ultrasonic receiving units provided so as to be symmetrical with respect to the rotation direction of the axis of the transducer. An ultrasonic diagnostic apparatus using the ultrasonic probe according to supplementary note 8, characterized in that:

10. An ultrasonic diagnostic apparatus that generates an ultrasonic image using an ultrasonic probe (virtual annular probe) that forms a virtual annular sound source or an ultrasonic probe that has a conical ultrasonic emission surface In, the thickness of the ultrasonic transducer constituting the ultrasonic probe is increased as the distance from the center of the ultrasonic transducer increases, and the ultrasonic transducer is divided into two or more concentrically with respect to the center axis of the ultrasonic transducer. An ultrasonic diagnostic apparatus comprising: first and second signal electrode portions provided respectively; and driving means for simultaneously driving high-frequency and low-frequency drive signals to the first and second signal electrode portions, respectively. 11. First separating means for extracting a high-frequency component for a short-range area after a short time from the echo signals output from the first and second signal electrode units; The ultrasonic diagnostic apparatus according to claim 10, further comprising: a second separating unit that extracts a low-frequency component for a region, and a combining unit that combines (adds) output signals of the first and second separating units. apparatus. (Function and Effect of Supplementary Note 11) An ultrasonic image having a high resolution in a short distance region using an ultrasonic component having a high frequency transmitted and received by a first signal electrode portion close to the center axis of the ultrasonic transducer, and an ultrasonic image An ultrasonic image having a good depth of penetration (high sound pressure) up to a long distance region by the second signal electrode unit away from the central axis of the transducer is synthesized, and sound field disturbance in a short distance region is suppressed, In addition, an ultrasonic image with good image quality can be obtained over a wide range of S / N far away.

[0069]

As described above, according to the present invention, the first ultrasonic vibrating portion having a circular shape, the first signal electrode portion provided on the first ultrasonic vibrating portion, the first ultrasonic vibrating portion, A second ultrasonic vibrating section having a structure thicker than the thickness of the first ultrasonic vibrating section and provided on the second ultrasonic vibrating section, which are provided concentrically outside the ultrasonic vibrating section. A second signal electrode unit;
An acoustic radiation surface of the second ultrasonic vibration part, or an ultrasonic radiation surface in which the first ultrasonic vibration part and the second ultrasonic vibration part have an ultrasonic radiation surface of a virtual circular or substantially conical surface shape. By forming a sound probe, a high-frequency drive pulse is applied to the first signal electrode portion and a low-frequency drive pulse is applied to the second signal electrode portion at a time to form a narrow beam over a wide range. In addition, the sound pressure at the distant place has been increased and the ultrasonic wave with suppressed side lobe can be transmitted.

A circular first ultrasonic vibrating section, a first signal electrode section provided on the first ultrasonic vibrating section, and a concentric circular outer side of the first ultrasonic vibrating section. A second ultrasonic vibration part having a structure thicker than the thickness of the first ultrasonic vibration part, and a second signal electrode part provided in the second ultrasonic vibration part, An ultrasonic probe having an acoustic radiation surface of a second ultrasonic vibrating portion, or an ultrasonic probe in which the first ultrasonic vibrating portion and the second ultrasonic vibrating portion have an ultrasonic radiation surface of a virtual annular or substantially conical surface shape. And a filter means for separating an echo signal from the ultrasonic probe by a frequency component, and a low frequency component obtained by the filter means to obtain an image of an observation target far from the ultrasonic probe. Used, the image of the observation target close to the ultrasonic probe is applied to the filter means. The ultrasonic diagnostic apparatus using the high-frequency component obtained by the above-described method allows the high-resolution ultrasonic image with the high-frequency component to be obtained for a close observation target and the S by the low-frequency component with good transparency to the distant observation target. /
Ultrasonic images with good N are obtained, and an ultrasonic image with good image quality can be obtained comprehensively over a wide area.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing features and the like of an ultrasonic probe according to the present invention.

FIG. 2 is a diagram showing a configuration of an ultrasonic probe according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus configured using the first embodiment of the present invention.

FIG. 4 is a diagram showing characteristics of an amplifier and a dynamic filter used in the embodiment;

FIG. 5 is a diagram showing a configuration of an ultrasonic probe according to a modified example.

FIG. 6 is a diagram showing a configuration of an ultrasonic probe according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic probe 2 ... Piezoelectric vibrator 3 ... Ground electrode 4, 5 ... Signal electrode part 5a, 5b, 5c, 5d ... Signal electrode pattern 6 ... Metal case 7 ... Insulating member 8 ... Notch part 9 ... Ground Connection line 10 Acoustic matching layer 11 Signal line 12 a, 12 b, 12 c, 12 d Signal line 13 Backing layer 14 Ground line 21 Ultrasonic diagnostic device 22 Observation device 23 Monitor 24 High frequency pulsar 25 Low Frequency pulsar 26, 27a, 27b, 27c, 27d ... Pulse / echo switch 28, 29a, 29b, 29c, 29d ... Amplifier 30, 31a, 31b, 31c, 31d ... Dynamic filter 33 ... Multiplier 34 ... Adder 35 … Image processing circuit

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[Procedure amendment]

[Submission Date] June 28, 1999 (1999.6.2
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction contents]

The ferrite rubber backing material 48 is adhered to the inner surface of the stainless steel case 6, and the signal electrodes 44, 45 and the signal receiving electrodes 46a, 46b, 46c of the composite piezoelectric vibrator 42 are respectively supplied with signals. Lines 11, 12
After connecting the receiving lines 52a, 52b, 52c with a conductive adhesive, the signal lines 11, 12 and the receiving lines 52a, 52b are inserted into the through holes 53a, 53b, 57c, 57d, 53e of the ferrite rubber backing material 48. , 52c
Through, the composite piezoelectric transducer 42 is bonded have use an epoxy adhesive to the front surface of the ferrite rubber backing material 48.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction contents]

The through holes 53a, 53b, 53c, 53d, 53e, 53 of the ferrite rubber backing material 48
After the epoxy resin mixed with ferrite rubber is poured into the f and cured, the back surface of the metal case 6 is closed by bonding a metal cover (not shown), and the entire surface of the ultrasonic probe 41 is covered with the above-described parylene. Coating (not shown)
And then attached to a rotary drive mechanism (not shown).

Claims (3)

[Claims] A first ultrasonic vibrating portion having a circular shape; a first signal electrode portion provided in the first ultrasonic vibrating portion; and a concentric outer shape of the first ultrasonic vibrating portion. A second structure having a thickness greater than a thickness of the first ultrasonic vibrating portion provided;
And a second signal electrode unit provided in the second ultrasonic vibration unit. An acoustic emission surface of the second ultrasonic vibration unit, or the first ultrasonic wave An ultrasonic probe, wherein the vibrating part and the second ultrasonic vibrating part have a virtual circular or substantially conical ultrasonic radiation surface. 2. The ultrasonic vibrator or ultrasonic vibrator group having a structure in which the first and second ultrasonic vibrators are continuously or stepwise thicker from the center, and the ultrasonic vibrator or ultrasonic wave A circular first signal electrode portion provided at the center of the vibrator group, and a second signal electrode portion provided concentrically outside the first signal electrode portion. The ultrasonic probe according to claim 1, wherein 3. A first ultrasonic vibrating portion having a circular shape, a first signal electrode portion provided on the first ultrasonic vibrating portion, and a concentric outer shape of the first ultrasonic vibrating portion. A second structure having a thickness greater than a thickness of the first ultrasonic vibrating portion provided;
And a second signal electrode unit provided on the second ultrasonic vibrating unit, wherein the acoustic radiation surface of the second ultrasonic vibrating unit or the first ultrasonic wave An ultrasonic probe in which an ultrasonic vibrating unit and a second ultrasonic vibrating unit each have an ultrasonic radiation surface having a virtual annular or substantially conical surface shape; and an echo signal from the ultrasonic probe is separated by a frequency component. Having a filter means, using a low frequency component obtained by the filter means to obtain an image of the observation object far from the ultrasonic probe, the image of the observation object close to the ultrasonic probe is the filter means An ultrasonic diagnostic apparatus characterized by using a high frequency component obtained by: