JP4338568B2 - Ultrasonic probe and ultrasonic diagnostic apparatus - Google Patents

Description

  The present invention relates to an ultrasonic probe and an ultrasonic diagnostic apparatus including the same, and more particularly to a structure of an ultrasonic transducer.

  As an ultrasonic transducer provided in an ultrasonic probe, a single transducer, a 1D array transducer, a 1.5D array transducer, a 2D array transducer, and the like are known. The structure of the 1D array transducer will be described below as a representative. The 1D array transducer includes a plurality of vibration elements (vibration elements) arranged in the array direction (first horizontal direction). Each vibration element has a form extending in the elevation direction (second horizontal direction). The plurality of vibration elements are manufactured by cutting a plate-shaped piezoelectric material at a predetermined pitch with a dicing saw. Each vibration element is provided with a pair of electrodes, and at the time of transmission, a high voltage is applied between them, thereby generating an ultrasonic wave. On the other hand, at the time of reception, when an ultrasonic wave reaches the vibration element, a voltage is generated between the pair of electrodes, and this is extracted as a reception signal.

  Usually, one or a plurality of matching layers are formed on the front side of the plurality of vibration elements, and an acoustic lens is provided thereon. The acoustic lens improves the acoustic focusing property in the elevation direction. A backing layer is provided on the back side of the plurality of vibration elements. The backing layer mainly has a function of scattering and absorbing ultrasonic waves emitted from the back surface or a function of reflecting ultrasonic waves emitted from the back surface. A backing layer is bonded to each vibration element, and the relationship between the physical characteristics (especially acoustic impedance) of both affects the ultrasonic vibration action.

  The backing layer is generally configured by mixing an additive such as metal particles in a base material such as resin or rubber. Although the acoustic impedance can be raised and brought close to the acoustic impedance of the vibration element by adding an additive, the acoustic impedance of the entire backing layer is usually smaller than the acoustic impedance of the vibration element. This case can be referred to as “light backing” in contrast to “heavy backing” described later.

  Numerous studies have been made on the backing layer (see Non-Patent Document 1 below). Here, it is known that the backing layer is formed of a member having an acoustic impedance larger (for example, 2 to 5 times) than the acoustic impedance of the vibration element. This case can be referred to as “heavy backing”. When performing heavy backing, the thickness of the backing layer is set sufficiently large. On the other hand, it is also known that heavy backing can be performed even if the thickness of the backing layer is set to λ / 8 (λ: wavelength of ultrasonic waves). However, the practical use of heavy backing is still not fully studied. In particular, it has not been proposed in the past to change the thickness of the heavy backing in the vertical direction.

Nakabachi, Tamura; Applied Physics, Volume 47 (No. 12, P.1162 (1978))

  An object of the present invention is to improve the operation characteristics of an ultrasonic transducer or improve the function of an ultrasonic transducer by utilizing the action of heavy backing.

  Another object of the present invention is to increase the bandwidth of an ultrasonic transducer.

  Another object of the present invention is to realize variable aperture in the elevation direction.

(1) An ultrasonic probe according to the present invention includes a vibration layer having a first acoustic impedance, and a backing layer provided on a lower surface side of the vibration layer, and the backing layer includes a heavy backing member. The heavy backing member is bonded to the lower surface side of the vibration layer, the vertical thickness of the heavy backing member changes in a horizontal direction, and the heavy backing member has a first larger acoustic impedance than the first acoustic impedance. 2 having an acoustic impedance, and changing the thickness of the heavy backing member in the vertical direction in the horizontal direction so that the wavelength of the ultrasonic wave is λ, at least λ depending on the position in the horizontal direction in the vibration layer The vibration is generated in the / 2 vibration mode and the λ / 4 vibration mode .

  According to the above configuration, the vibration mode is changed according to the position in the horizontal direction in the vibration layer due to the change in the vertical thickness of the heavy backing member, thereby improving the frequency characteristics of the vibration layer. In a particularly desirable mode, a λ / 2 vibration mode and a λ / 4 vibration mode are generated in the vibration layer, thereby broadening the vibration layer. In addition, if necessary, the characteristics of the transmission signal supplied to the vibration layer can be varied, for example, the center frequency and band can be varied, and the vibration mode in the vibration layer can be electrically controlled. The second acoustic impedance is larger than the first acoustic impedance, preferably set to a value of 1.2 times or more, and particularly preferably set to 2 to 10 times. Of course, a larger value may be used. The third acoustic impedance of the light backing layer to be described later is set to a value smaller than the first and second acoustic impedances. Preferably, the third acoustic impedance is about 1/10 to 1/50, for example, than the second acoustic impedance. small. Of course, the ratio may be made smaller. In the above, the vertical direction means the main propagation direction of ultrasonic waves, and the horizontal direction is a direction orthogonal to the vertical direction.

  Preferably, the vertical thickness of the heavy backing member continuously changes in the horizontal direction. Although it is possible to change the thickness of the heavy backing layer in the vertical direction step by step, good characteristics can be obtained if it changes continuously.

  Desirably, when the wavelength of the ultrasonic wave is λ, the change width of the thickness of the heavy backing member in the vertical direction is set so that the vibration layer can vibrate at least in the λ / 2 vibration mode and the λ / 4 vibration mode. Is done. The λ / 2 vibration mode can be realized by clamping (fixing) the lower surface side of the vibration layer by a heavy backing action, while λ / 4 can be realized by making the lower surface side of the vibration layer behave like a free end by a light backing action. Vibration mode can be realized. The light backing function can be realized, for example, by partially reducing the thickness of the heavy backing member that is joined to the entire lower surface of the vibration surface, and the light backing layer is provided on the portion of the lower surface of the vibration layer from which the heavy backing member is removed. It can also be realized by bonding.

  Preferably, the backing layer further includes a light backing layer that is provided together with the heavy backing member and has a third acoustic impedance smaller than the second acoustic impedance. The light backing layer is composed of a light backing member or an air layer.

(2) An ultrasonic probe according to the present invention has a first acoustic impedance, a vibration layer including a plurality of vibration elements aligned in a first horizontal direction as an array direction, A backing layer provided on a lower surface side, the backing layer including a heavy backing member, the heavy backing member being bonded to the lower surface side of the vibration layer, wherein the thickness of the heavy backing member in the vertical direction is base change in the second horizontal direction as Shon direction, the heavy backing member, said first than the acoustic impedance have a larger second acoustic impedance, said second horizontal direction vertical thickness of the heavy backing member When the wavelength of the ultrasonic wave is λ, the vibration layer has at least a λ / 2 vibration mode according to the position in the horizontal direction. And λ / 4 vibration mode is generated .

  According to the above configuration, since the thickness of the heavy backing member in the vertical direction changes in the elevation direction, the frequency characteristics of the vibration element in the elevation direction can be changed. Desirably, variable aperture in the elevation direction can be realized by changing the characteristics of the transmission signal on the premise of the above configuration.

  Desirably, the thickness of the heavy backing member continuously increases in the vertical direction from the center portion in the second horizontal direction to both end portions. According to this configuration, the vibration mode or the resonance frequency can be made different between the central portion and the end portion. For example, transmission with the central portion as the main vibration portion, transmission with the end portion as the main vibration portion, and transmission that vibrates the whole can be selectively performed.

(3) An ultrasonic probe according to the present invention includes a vibration layer having a first acoustic impedance and including a plurality of vibration elements aligned in a first horizontal direction and a second horizontal direction, and the vibration layer. A backing layer configured by a plurality of backing elements provided corresponding to the plurality of vibration elements, each backing element includes a heavy backing member, and the heavy backing member is large, is joined to the lower surface side of the vibrating element, the vertical thickness of the heavy backing member is changed to the first horizontal direction and the second horizontal direction, wherein the heavy backing member, than said first acoustic impedance It has a second acoustic impedance, by changing the vertical direction of the thickness of the heavy backing member to the first horizontal direction and said second horizontal direction If the wavelength of ultrasonic lambda, vibrations at least lambda / 2 vibration mode and lambda / 4 vibration mode occurs in response to the position of the first horizontal direction and the second horizontal direction in the vibration layer, the Features.

  According to the above configuration, since the thickness of the heavy backing member in the backing element to be joined for each vibration element changes, it is possible to generate a plurality of or various vibration modes in each vibration element. Thus, the characteristics of each vibration element can be improved. In a particularly desirable mode, each vibration element has a wide band.

  Preferably, the lower surface of the heavy backing member in each of the backing elements has a concave or convex shape.

(4) Moreover, the ultrasonic probe according to the present invention is an ultrasonic diagnostic apparatus constituted by an ultrasonic probe and an apparatus main body to which the ultrasonic probe is connected. A vibration layer having a plurality of vibration elements having impedance and arranged in the array direction, and an elevation that is provided on the lower surface side of the vibration layer and whose vertical thickness is perpendicular to the array direction A heavy backing member having a second acoustic impedance greater than the first acoustic impedance, wherein a vertical thickness of the heavy backing member is defined in the elevation direction. When the wavelength of the ultrasonic wave is λ by changing, at least in the λ / 2 vibration mode and the λ / 4 vibration mode in the vibration layer according to the position in the elevation direction. Dynamic occurs, the device body has a connected transceiver to the vibration layer, and means for controlling the operation of the transceiver unit, a control unit for changing the characteristics of the transmission signal supplied to the vibration layer It is characterized by including.

  According to the above configuration, it is possible to electrically control the vibration state in the vibration layer by changing the characteristics of the transmission signal.

  Desirably, when the wavelength of the ultrasonic wave is λ, the change width of the thickness of the heavy backing member in the vertical direction is set so that the vibration layer can vibrate at least in the λ / 2 vibration mode and the λ / 4 vibration mode. The control unit sets the characteristics of the transmission signal so that the vibration layer can vibrate in the λ / 4 vibration mode during short-distance transmission, and the vibration layer is in at least the λ / 2 vibration mode during long-distance transmission. The characteristics of the transmission signal are set so as to vibrate.

  Preferably, the transmission / reception unit supplies a narrow band transmission signal to each vibration element to partially excite each vibration element to narrow a transmission opening in the elevation direction, and transmits a wide band to each vibration element. By supplying a signal, the vibration elements are entirely excited to widen the transmission aperture in the elevation direction.

  As described above, according to the present invention, it is possible to improve the operation characteristics of the ultrasonic vibrator or improve the function of the ultrasonic vibrator by utilizing the action of heavy backing. According to the present invention, the ultrasonic transducer can be widened. According to the present invention, variable opening can be realized in the elevation direction.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram showing the main part of an ultrasonic transducer according to the present invention. This ultrasonic transducer is provided in an ultrasonic probe which will be described later. Ultrasonic waves are transmitted and received by the ultrasonic transducer, and an ultrasonic image is constructed based on the received signals obtained thereby. The ultrasonic image is an image used for diagnosis of a living body.

In FIG. 1A, the X direction and the Y direction are horizontal directions, specifically, the X direction is an array direction, and the Y direction is an elevation direction. The Z direction is an ultrasonic wave transmission / reception direction. As shown in the figure, the vibration element 10 has a rectangular shape extending in the Y direction. The vibration element 10 is composed of PZT as a piezoelectric material, a composite material, or the like. Its acoustic impedance is Z _P. Further, the thickness in the Z direction is represented by t _P.

A matching layer 11 is provided on the upper surface side of the vibration element 10. Specifically, the matching layer 11 includes a first matching layer 12 and a second matching layer 14. Further, an acoustic lens is provided on the upper surface side of the matching layer 11, but this is not shown. The matching layer 11 is a member for matching the acoustic impedance between the acoustic impedance Z _P of the vibration element 10 and the acoustic impedance of the living body.

  In the vibration element 10, electrodes (signal electrodes and ground electrodes) are formed on the upper and lower surfaces, but these electrodes are not shown in FIG. 1.

  A backing layer 15 is provided on the lower surface side of the vibration element 10. In this embodiment, the backing layer 15 exhibits a heavy backing action, a light backing action, or the like on the lower surface side of the vibration element 10, and is thereby provided to operate the vibration mode of the vibrator 10 at each part in the Y direction. . Of course, like the conventional backing layer, this backing layer 15 may have actions such as absorption, scattering and reflection of ultrasonic waves.

The backing layer 15 has a heavy backing member 16 as shown. A light backing member is provided as necessary, which will be described later. As shown in the figure, the heavy backing member 16 has its upper surface entirely joined to the lower surface of the vibration element 10. Further, as shown in FIG. 1, the bottom surface of the heavy backing member 16 has an arc shape or a curved surface along the Y direction. That is, the thickness t _HB of the heavy backing member 16 is continuously increased along the Y direction. It is variable. Specifically, in the example shown in FIG. 1, the heavy backing member 16 has the smallest thickness at the center in the Y direction, and the thickness is large at both ends in the Y direction.

The heavy backing member 16 has an acoustic impedance Z _HB , and the acoustic impedance Z _HB is larger than the acoustic impedance Z _P of the vibration element 10. Desirably, it is 1.2 times or more larger, and particularly desirably twice or more larger.

  Since the heavy backing member 16 has a form having a thickness change in the Y direction as described above, a light backing action acts on the vibration element 10 in the central portion in the Y direction as shown in FIG. That is, the heavy backing action is weakened, and ideally the lower surface side of the vibration element 10 acts as an open end, and vibrates in the 2f vibration mode, in other words, in the λ / 4 vibration mode. On the other hand, since the thickness of the end portion in the Y direction in the heavy backing member 16 is increased, and desirably the thickness is λ / 8 or sufficiently large, the end portion on the lower surface of the vibration element 10 is It is clamped by the heavy backing action, and ideally vibrates in the f vibration mode as shown in (C), that is, in the λ / 2 vibration mode. That is, a change in the Y-direction vibration mode in the vibration element 10 due to a change in the thickness in the Y direction of the heavy backing member 16 causes a change in resonance characteristics at each position in the Y direction. It becomes possible to increase the bandwidth. In this case, since the thickness of the backing layer 15 is continuously varied, it is possible to suppress improper vibrations or phase disturbances and to obtain good frequency characteristics.

  This will be described with reference to FIG. In FIG. 2, the frequency characteristic of the vibration element 10 is shown, the horizontal axis represents the frequency, and the vertical axis represents the response. As a result of the heavy backing action as shown in (C) above at the end in the Y direction, a frequency characteristic centered on the frequency f as shown by reference numeral 200 can be obtained, while vibrations In the central portion of the element 10, the heavy backing action as shown in the above (B) works, and a frequency characteristic having the frequency 2f as the center frequency can be obtained as indicated by reference numeral 202 in FIG. Accordingly, a broadband frequency characteristic as indicated by reference numeral 204 is obtained for the entire vibration element 10. Thus, the frequency characteristics of the vibration element 10 can be improved by adjusting the form or structure of the backing layer without performing special processing on the vibration element 10, and as described later, as described above. It is possible to control the transmission aperture using a simple configuration.

  In the example shown in FIG. 1, the heavy backing member 16 is configured to gradually increase in thickness from the center to both ends in the Y direction, but as shown in FIG. 3, the one end from the other end to the other end in the Y direction. A heavy backing member 16A that gradually increases or decreases in thickness can be employed. Alternatively, as shown in FIG. 4, a heavy backing member 16 </ b> B having a large thickness at the center in the Y direction and a thickness reduced at both ends can be employed. Of course, you may make it employ | adopt forms other than the form shown by those figures.

In the example shown in FIG. 5, a backing layer 15 is provided on the lower surface side of the vibration element 10, and the heavy backing layer 15 is composed of a heavy backing member 16 </ b> C and a light backing member 18. The bottom surface of the heavy backing member 16C has a shape change as illustrated along the Y direction, and specifically has an S-shaped cross-sectional shape from the center to both ends. In the example shown in FIG. 5, the thickness of the heavy backing layer 16 </ b> C is 0 or substantially 0 at the center portion, and the end portion has a thickness sufficient to exhibit the heavy backing action. Reference numeral 22 represents a pedestal, and the backing layer 15 is bonded onto the pedestal 22. Here, when the acoustic impedances of the vibration element 10, the heavy backing member 16C, and the light backing member 18 are Z _P , Z _HB , and Z _SB , as shown in the figure, the relationship of Z _HB > Z _P > Z _SB Is established.

  That is, the light backing member 18 has an acoustic impedance smaller than that of the vibration element 10 and the heavy backing member 16C, and the value thereof is, for example, a fraction of 1 to several tenths of the acoustic impedance of the heavy backing member 16C. is there.

  It should be noted that it is desirable to sufficiently increase the thickness of the backing layer 15 or to appropriately set the acoustic impedance of the pedestal 22 in relation to the backing layer 15 so as not to adversely affect the vibration of the vibration element 10.

  FIG. 6 shows still another example. A backing layer 15 is provided on the lower surface side of the vibration element 10, and the backing layer 15 includes a heavy backing member 16D and a light backing member 18A. However, although the thickness of the heavy backing member 16D as a whole changes continuously along the Y direction, it is completely removed at the central portion in the Y direction. It is joined to the upper surface of the backing member 18A. Here, the thickness change of each member 16D and 18A has arisen according to the part which gives a heavy backing action, and the part which gives a light backing action. However, as described above, it is desirable that the thickness of the heavy backing member 16D and the like continuously change along the Y direction in order to prevent improper vibration and the like and not to adversely affect the phase. In the example shown in FIG. 6, both ends of the backing layer 15 are held by the pedestal 22A. That is, as shown in FIG. 6, when holding the backing layer 15, a pedestal may be bonded to the lower surface side, or may be held by the pedestal from the side surface side.

  Next, the configuration of the ultrasonic diagnostic apparatus according to the present embodiment will be described with reference to FIG. The ultrasonic diagnostic apparatus includes a probe 104 as an ultrasonic probe and an apparatus main body 108, and the probe 104 and the apparatus main body 108 are connected by a probe cable 106.

  The array transducer 30 includes a plurality of vibration elements 10 aligned in the X direction, that is, the array direction. In general, a plurality of vibration elements 10 are configured by cutting a flat plate member made of PZT or the like with a dicing saw. In such cutting, a part or the whole of the backing layer 15 may be cut in the Z direction as necessary. According to such a configuration, acoustic wraparound, that is, crosstalk can be effectively reduced.

  The backing layer 15 is composed of a heavy backing member 32 and a light backing member 34 having the same acoustic impedance relationship as that shown in FIG. The upper surface of the heavy backing member 32 is joined to the lower surface of each vibration element 10, and the lower surface of the heavy backing member 32 is curved along the Y direction. That is, the thickness of the heavy backing member 32 continuously changes along the Y direction. A light backing member 34 is provided so as to compensate for the change in thickness, and the light backing member 34 has a thickness that continuously changes along the Y direction, and its central portion has the largest thickness, The both end portions have the smallest thickness. The backing layer 15 is formed in a flat plate shape by a combination of the heavy backing member 32 and the light backing member 34. The light backing member 34 can be manufactured by filling with a filler. The backing layer 15 is fixed on the base 36.

  As described with reference to FIG. 1, when the backing layer 15 has the above-described configuration, when attention is paid to the Y direction, each vibration element 10 performs different vibration operations at the center portion and both end portions in the Y direction.

  The apparatus main body 108 includes a transmission / reception unit 60 and a transmission / reception control unit 62 as shown in the figure. The transmission / reception unit 60 functions as a transmission beam former and a reception beam former. That is, the transmission / reception unit 60 supplies a plurality of transmission signals to the plurality of vibration elements 10 at the time of transmission, while phasing addition processing is performed on the plurality of reception signals output from the plurality of vibration elements 10 at the time of reception. Execute. The transmission / reception control unit 62 controls the operation of the transmission / reception unit 60. In particular, control is performed to vary the center frequency and band of the transmission signal.

  In the present embodiment, as shown in FIG. 7, in the case of short-distance transmission, a narrow-band transmission signal having a center frequency of 2f is supplied to each vibration element, thereby the array transducer 30. The center portion 100 in the Y direction mainly vibrates, that is, vibrates in the 2f mode, and a small transmission aperture is realized in the Y direction, that is, the elevation direction. On the other hand, in the case of long-distance transmission, a wideband transmission signal covering the frequencies of f and 2f is supplied to each vibration element 10 as a transmission signal. The entire end 102 vibrates, resulting in a large transmission aperture. In this case, the component of the frequency f brings about a vibration action at the end portion 102, and the component of the frequency 2f brings about a vibration action at the center portion.

  As described above, it is possible to electrically control the vibration range in the elevation direction of the array transducer 30 by changing the band of the transmission signal, and it is possible to adjust the transmission aperture according to the diagnostic distance as described above. It becomes. In long-distance transmission, it is also possible to supply a transmission signal of f and thereby exert an oscillating action around the end 102.

  In the harmonic imaging mode and the like, transmission is performed with the fundamental wave, and the harmonic component generated in the living body is received. Even in such a mode, the ultrasonic transducer according to the present embodiment increases the bandwidth. Therefore, sufficient characteristics can be obtained in both transmission and reception.

  In the example shown in FIG. 7, the thickness of the heavy backing member 32 is varied only in the elevation direction, but instead of or in addition to that, the thickness of the heavy backing member 32 is continuously increased in the array direction. It may be variable. That is, in FIG. 7, the thickness may be the thinnest at the central portion in the X direction, and the thickness may be increased from there to both ends in the X direction.

  FIG. 8 shows a 2D array transducer 40 to which the principle described above is applied. The 2D array transducer 40 includes a plurality of vibration elements 42 that are two-dimensionally arranged. In FIG. 8, 4 × 4 vibrating elements 42 are shown for the sake of explanation, but in the actual 2D array transducer 40, more vibrating elements are provided. A backing layer 44 is bonded to the lower side of the 2D array transducer 40. The backing layer 44 includes a plurality of backing elements 46 corresponding to the arrangement of the plurality of vibration elements 42. However, each backing element 46 may be physically configured as a separate body, or may be integrated.

  9 and 10 show a section through the backing element 46. Each backing element 46 is constituted by a heavy backing member 48 and a light backing member 50. In the example shown in FIG. 9, the heavy backing member 48 has a concave shape facing downward, while the light backing member 50 has a convex shape facing upward. That is, the heavy backing member 48 has a form in which the thickness increases from the center to the end in both the X direction and the Y direction. On the other hand, the thickness of the light backing member 50 is gradually reduced in the horizontal direction from the center. In the example shown in FIG. 10, contrary to the example shown in FIG. 9, the heavy backing member 48 has a form in which the thickness is gradually reduced from the central part to the peripheral part, that is, has a convex form downward. . On the other hand, the light backing member 50 has a form in which the thickness is gradually increased from the central part to the peripheral part, in contrast to the heavy backing member 48, that is, has a concave form toward the top.

  In any case, since the heavy backing member 48 has a concave shape or a convex shape in each backing element 46, the thickness of the heavy backing member 48 is changed in the horizontal direction, and as a result, the vibration mode as described above is achieved. It is possible to increase the bandwidth of each vibration element 42 by generating diversity.

It is a conceptual diagram which shows suitable embodiment of the ultrasonic transducer | vibrator which concerns on this invention. It is a figure which shows the frequency characteristic of the ultrasonic probe shown in FIG. FIG. 6 shows an embodiment having an inclined heavy backing member. It is a figure which shows embodiment which has a convex spherical-shaped heavy backing member. It is a figure which shows embodiment which combined the heavy backing member and the light backing member. It is a figure which shows other embodiment which combined the heavy backing member and the light backing member. It is a conceptual diagram which shows the principal part structure of an ultrasonic diagnosing device. It is a figure which shows the structure of a 2D array vibrator | oscillator. It is a figure which shows the cross section of a backing element. It is a figure which shows the cross section of a backing element.

Explanation of symbols

  10 vibration element, 11 matching layer, 15 backing layer, 16 heavy backing member, 18 light backing member.

Claims (11)

A vibration layer having a first acoustic impedance;
A backing layer provided on the lower surface side of the vibration layer;
Including
The backing layer includes a heavy backing member;
The heavy backing member is bonded to the lower surface side of the vibration layer,
The vertical thickness of the heavy backing member changes in the horizontal direction ,
The heavy backing member has a second acoustic impedance greater than the first acoustic impedance;
By changing the vertical thickness of the heavy backing member in the horizontal direction so that the wavelength of the ultrasonic wave is λ, at least the λ / 2 vibration mode and λ / in the vibration layer according to the position in the horizontal direction. An ultrasonic vibrator characterized in that vibration occurs in four vibration modes . The apparatus of claim 1.
The ultrasonic transducer according to claim 1, wherein the vertical thickness of the heavy backing member continuously changes in the horizontal direction. The ultrasonic probe according to claim 2 ,
The ultrasonic probe according to claim 1, wherein a thickness of the heavy backing member in a vertical direction continuously increases from a center portion in the horizontal direction to both ends of the heavy backing member . The ultrasonic probe according to claim 1,
The ultrasonic probe further comprising a light backing layer that is provided together with the heavy backing member and has a third acoustic impedance smaller than the second acoustic impedance. A vibration layer comprising a plurality of vibration elements having a first acoustic impedance and aligned in a first horizontal direction as an array direction;
A backing layer provided on the lower surface side of the vibration layer;
Including
The backing layer includes a heavy backing member;
The heavy backing member is bonded to the lower surface side of the vibration layer,
The vertical thickness of the heavy backing member changes in the second horizontal direction as the elevation direction ;
The heavy backing member, have a larger second acoustic impedance than the first acoustic impedance,
By changing the vertical thickness of the heavy backing member in the second horizontal direction, when the wavelength of the ultrasonic wave is λ, at least λ / 2 vibrations in the vibration layer according to the position in the second horizontal direction. An ultrasonic vibrator characterized in that vibration occurs in a mode and a λ / 4 vibration mode . The ultrasonic probe according to claim 5,
The ultrasonic probe according to claim 1, wherein a thickness of the heavy backing member in a vertical direction continuously increases from a center portion in the second horizontal direction to both ends of the heavy backing member . A vibration layer including a plurality of vibration elements having a first acoustic impedance and aligned in a first horizontal direction and a second horizontal direction;
A backing layer provided on the lower surface side of the vibration layer and configured by a plurality of backing elements provided corresponding to the plurality of vibration elements;
Including
Each backing element includes a heavy backing member;
The heavy backing member is bonded to the lower surface side of the vibration element,
The vertical thickness of the heavy backing member changes in the first horizontal direction and the second horizontal direction ;
The heavy backing member, have a larger second acoustic impedance than the first acoustic impedance,
By changing the thickness of the heavy backing member in the vertical direction in the first horizontal direction and the second horizontal direction, when the wavelength of the ultrasonic wave is λ, the first horizontal direction and the second in the vibration layer. An ultrasonic transducer characterized in that vibration occurs in at least a λ / 2 vibration mode and a λ / 4 vibration mode according to a position in a horizontal direction . The ultrasonic probe according to claim 7,
The ultrasonic probe according to claim 1, wherein a lower surface of the heavy backing member in each of the backing elements has a concave or convex shape. In an ultrasonic diagnostic apparatus composed of an ultrasonic probe and an apparatus main body to which the ultrasonic probe is connected,
The ultrasonic probe is
A vibration layer having a first acoustic impedance and composed of a plurality of vibration elements arranged in an array direction;
A second acoustic impedance which is provided on the lower surface side of the vibration layer and has a shape in which the vertical thickness of the vibration layer changes in an elevation direction perpendicular to the array direction, and which is larger than the first acoustic impedance. A heavy backing member with
Including
By changing the vertical thickness of the heavy backing member in the elevation direction so that the wavelength of the ultrasonic wave is λ, at least λ / 2 vibration in the vibration layer according to the position in the elevation direction. Vibration in mode and λ / 4 vibration mode occurs,
The device body is
A transmission / reception unit connected to the vibration layer;
An ultrasonic diagnostic apparatus, comprising means for controlling operation of the transmission / reception unit, wherein the control unit varies a characteristic of a transmission signal supplied to the vibration layer. The apparatus of claim 9.
The ultrasonic transducer according to claim 1, wherein a thickness of the heavy backing member in a vertical direction continuously changes in the horizontal direction . The apparatus of claim 9.
The transmission / reception unit supplies a narrow band transmission signal to each vibration element, partially excites each vibration element to narrow a transmission opening in the elevation direction, and supplies a wide band transmission signal to each vibration element. Thus, the ultrasonic diagnostic apparatus is characterized in that the transmission elements in the elevation direction are widened by exciting the vibration elements as a whole.

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