JP4842010B2 - Ultrasonic probe and ultrasonic diagnostic apparatus - Google Patents

Description

The present invention relates to an ultrasonic probe and an ultrasonic diagnostic apparatus in which a plurality of transducers that transmit and receive ultrasonic waves to and from a subject are arranged.

  The ultrasound probe converts the electrical signal supplied from the ultrasound diagnostic device into ultrasound and transmits it to the subject, and receives the reflected echo generated from the subject and converts it into a received signal. Multiple children are arranged. As this vibrator, MUT (Micromachined Ultrasonic Transducers) manufactured by ultrafine processing using micromachine technology such as semiconductor manufacturing technology is known. For example, cMUT (Capacitive Micromachined Ultrasonic Transducers), which is one form of MUT, forms a single vibrator by providing a plurality of vibration elements on a semiconductor substrate formed of a semiconductor such as silicon. This vibration element has a structure in which a vibration film provided on a semiconductor substrate is supported by a support portion, and a sacrificial layer such as a vacuum or air is formed between the semiconductor substrate and the vibration film. In addition, electrodes are provided on the semiconductor substrate and the vibration film, respectively, and an ultrasonic signal is transmitted to the subject by vibrating the vibration film by supplying an electric signal to the electrode and reflected from the subject. Receives the received signal by vibrating the vibrating membrane. Here, when the vibrating membrane vibrates, the ultrasonic wave generated due to the vibration propagates to the semiconductor substrate through the support portion, and the inside of the semiconductor substrate is affected by the back surface portion provided on the back surface side of the semiconductor substrate. Multiple reflection occurs. Thereby, an ultrasonic wave (hereinafter referred to as a plate wave) in which a specific frequency is emphasized is generated, and the plate wave propagates to the vibration film of the adjacent vibration element via the support portion of the adjacent vibration element. Then, unnecessary vibrations of the vibrating membranes of the adjacent vibrating elements cause degradation of temporal, frequency, and spatial resolution.

  Patent Document 1 describes that a cut groove is provided from the surface in a portion between vibration elements of a semiconductor substrate of a cMUT vibrator, and a porous member is provided in the cut groove. According to this, it is said that the plate wave generated inside the semiconductor substrate can be prevented from propagating to the adjacent vibration element.

Patent Document 2 describes that an acoustic matching layer is provided between the semiconductor substrate and the back surface portion of the cMUT vibrator, whereby the ultrasonic wave propagated to the semiconductor substrate is reflected by the back surface member. Can be suppressed.
US Pat. No. 6,262,946 US Pat. No. 6,831,394

  However, the technique described in Patent Document 1 suppresses the propagation of plate waves inside the semiconductor substrate, and the technique described in Patent Document 2 reflects the ultrasonic wave propagated to the semiconductor substrate at the back surface portion. This suppresses the generation of plate waves. That is, since both technologies deal only with the ultrasonic wave after propagating to the semiconductor substrate, the plate wave propagating to the vibration film of the adjacent vibration element cannot be sufficiently suppressed, and the vibration film of the adjacent vibration element cannot be suppressed. Unnecessary vibration may occur.

  It is an object of the present invention to suppress interference generated between adjacent vibration elements due to vibration of a vibration film.

  In order to solve the above-described problem, a first aspect of the ultrasonic probe of the present invention includes a plurality of transducers that mutually convert ultrasonic waves and electrical signals, and the transducers are arranged on a substrate and a substrate. The vibration element includes a plurality of vibration elements provided, and the vibration element includes a vibration film provided on the substrate, and a support unit that supports the vibration film by forming a space between the vibration film and the substrate. Is provided with a sound insulation portion for suppressing ultrasonic waves propagating between the vibration film and the substrate.

  In other words, the plate wave is generated when the ultrasonic wave propagates from the vibrating membrane side to the substrate through the support part. Therefore, by providing a sound insulation part inside the support part, the propagation of the ultrasonic wave to the substrate is suppressed. The generation of plate waves can be suppressed. Moreover, the plate wave propagating from the substrate to the vibration film of the adjacent vibration element can be suppressed by the sound insulation portion provided inside the support portion of the adjacent vibration element. In other words, the generation of plate waves is suppressed, and the generated plate waves are suppressed from propagating to the vibration film of the adjacent vibration element, so that interference generated between adjacent vibration elements due to vibration of the vibration film is suppressed. Can do.

  In this case, it is desirable that the sound insulating portion is provided adjacent to the substrate. That is, by providing a sound insulation part adjacent to the substrate, the ultrasonic wave propagating from the vibration film side to the substrate and the plate wave propagating from the substrate to the vibration film of the adjacent vibration element are reliably incident on the sound insulation part. As a result, it is possible to more effectively suppress interference generated between adjacent vibration elements due to vibration of the vibration film.

  Moreover, it is desirable that the sound insulating part is a low acoustic impedance part having an acoustic impedance lower than that of either the support part or the substrate. That is, a part of the ultrasonic wave to be propagated from the vibrating membrane side to the substrate is reflected due to the difference in acoustic impedance when entering the substrate from the low acoustic impedance portion and when entering the substrate from the low acoustic impedance portion. To do. Similarly, part of the plate wave that is about to propagate from the substrate to the vibration film of the adjacent vibration element is also reflected by the difference in acoustic impedance. Thereby, generation | occurrence | production of a plate wave can be suppressed and it can suppress that the generated plate wave propagates to the vibration film of the adjacent vibration element.

  Furthermore, the sound insulating part may be a sound absorbing part that absorbs ultrasonic waves. That is, by mixing metal powders having different acoustic characteristics with the porous member serving as the base, it is possible to absorb the sound by scattering the ultrasonic waves and plate waves incident on the sound absorbing portion inside the sound absorbing portion. Thereby, generation | occurrence | production of a plate wave can be suppressed and it can suppress that the generated plate wave propagates to the vibration film of the adjacent vibration element.

  The second aspect of the ultrasonic probe according to the present invention includes a plurality of transducers that mutually convert ultrasonic waves and electrical signals. The transducer includes a substrate and a plurality of transducers provided on the substrate. The vibration element includes a vibration film provided on the substrate, and a support part that supports the vibration film by forming a space between the vibration film and the substrate. Are provided with a low acoustic impedance part having a lower acoustic impedance than any of the support part and between the vibrating film and the substrate on the side of the support part that faces the substrate of the low acoustic impedance part. A sound absorbing portion for absorbing the ultrasonic wave propagating through the sound wave is provided.

  Thus, by providing the low acoustic impedance part and the sound absorbing part along the propagation direction of the ultrasonic wave or plate wave inside the support part, the propagation of the ultrasonic wave or plate wave can be more effectively suppressed. Interference generated between adjacent vibration elements due to vibration of the vibration film can be more effectively suppressed.

  Furthermore, in the third aspect of the ultrasonic probe of the present invention, a plurality of transducers that mutually convert ultrasonic waves and electrical signals are arranged, and the transducers include a substrate and a base film provided on the substrate. And a plurality of vibration elements provided on the base film, wherein the vibration element forms a space between the vibration film provided opposite to the base film and the vibration film and the base film. And a sound insulating part that suppresses the ultrasonic wave propagating between the vibration film and the substrate is provided inside the base film. In this case, the sound insulation portion is provided in a portion sandwiched between the support portion of the base film and the substrate, and the end portion of the sound insulation portion is extended to the lower portion of the space formed between the vibration film and the base film. It is desirable that

  That is, since the sound insulating part is provided in a layer different from the space formed between the vibration film and the base film, the degree of freedom in designing the sound insulating part thickness, shape, etc. is increased, and the end of the sound insulating part is connected to the vibration film. It can extend to the lower part of the space formed between the base film. Thereby, since the ultrasonic wave and the plate wave are more reliably incident on the sound insulating portion and are suppressed, it is possible to more effectively suppress the interference generated between the adjacent vibration elements due to the vibration of the vibration film. it can.

  According to the present invention, it is possible to suppress interference generated between adjacent vibration elements due to vibration of the vibration film.

  Hereinafter, embodiments of an ultrasonic probe and an ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to FIGS. In the following description, the same functional parts are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a diagram illustrating a configuration of an ultrasonic probe and an ultrasonic diagnostic apparatus according to the first embodiment.
As shown in FIG. 1, the ultrasonic diagnostic apparatus 1 converts a drive signal into an ultrasonic wave and transmits it to a subject, and also receives an ultrasonic wave generated from the subject and converts it into an electrical signal. Are arranged, a transmitter 3 for supplying a drive signal to the ultrasound probe 2, and a DC bias voltage superimposed on the drive signal supplied to the ultrasound probe 2. Biasing means 4 to be applied, receiving means 6 for processing an electric signal (hereinafter referred to as a reflected echo signal) output from the ultrasound probe 2, and digital phasing with respect to the reflected echo signal output from the receiving means 6 And a phasing addition means 7 for performing addition processing, an image processing means 8 for reconstructing an ultrasonic image based on a reflected echo signal output from the phasing addition means 7, and an ultrasonic image output from the image processing means 8. Display means 9 for displaying The transmission unit 3, the bias unit 4, the reception unit 6, the phasing addition unit 7, the image processing unit 8, and the display unit 9 are connected to the control unit 10 respectively. Is controlled on the basis.

  Next, the operation of the ultrasonic diagnostic apparatus 1 will be described. A direct current bias voltage is supplied from the bias means 4 to the ultrasonic probe 2 brought into contact with the subject, and a drive signal is supplied from the transmission means 3 in a superimposed manner. The supplied drive signal is converted into an ultrasonic wave by each transducer of the ultrasonic probe 2 and transmitted to the subject. The ultrasonic wave reflected by the subject is received by each transducer of the ultrasound probe 2 and converted into a reflected echo signal by each transducer. The reflected echo signal output from the ultrasound probe 2 is subjected to reception processing such as amplification and analog-digital conversion by the reception means 6. The reflected echo signal subjected to the reception processing is subjected to phasing addition by the phasing addition unit 7, and the reflected echo signal subjected to the phasing addition is subjected to an ultrasonic image (for example, a tomographic image or a blood flow image) by the image processing unit 8. Of the diagnostic image). The reconstructed diagnostic image is displayed on the display means 9.

  FIG. 2 is a perspective view of the ultrasonic probe 2 according to the first embodiment. As shown in FIG. 2, the ultrasonic probe 2 is formed in a one-dimensional array type in which a plurality of transducers 12a to 12m (m: a natural number of 2 or more) are arranged in a strip shape. However, the present invention can also be applied to ultrasonic transducers of other forms such as a two-dimensional array type in which transducers are two-dimensionally arranged or a convex type in which transducers are arranged on a fan shape. A backing layer 13 is provided on the back side of the transducers 12a to 12m, and an acoustic lens 14 is provided on the ultrasonic emission side. It should be noted that a configuration in which the acoustic lens 14 is not used can be made by arranging the vibrators two-dimensionally. Further, an acoustic matching layer can be provided between the transducers 12a to 12m and the acoustic lens 14 as necessary.

  The transducers 12a to 12m convert the drive signal from the transmission unit 3 into an ultrasonic wave and transmit the ultrasonic wave to the subject, and receive the ultrasonic wave reflected by the subject and convert it into an electrical signal. The backing layer 13 suppresses excessive vibration of the transducers 12a to 12m by absorbing the propagation of ultrasonic waves emitted from the transducers 12a to 12m to the back side. The acoustic lens 14 converges the ultrasonic beam emitted from the transducers 12a to 12m. The arrangement direction of the vibrators 12a to 12m is a major axis direction X, and a direction orthogonal to the major axis direction X is a minor axis direction Y.

  FIG. 3 is an enlarged perspective view of one transducer 12 among the plurality of transducers 12a to 12m in FIG. As shown in FIG. 3, the vibrator 12 is formed on the substrate 15 with a plurality of vibration elements 16 a to 16 n (n: a natural number of 2 or more). The vibration elements 16a to 16n are electro-acoustic conversion elements in which an electromechanical coupling coefficient, that is, transmission / reception sensitivity changes depending on the magnitude of the applied DC bias voltage. The vibration elements 16a to 16n are arranged at substantially equal intervals in the major axis direction X and the minor axis direction Y, and adjacent vibration elements are connected by an electrode 17a. In this embodiment, the electrodes 17a are connected to the upper, middle, and lower sections along the minor axis direction Y. However, the present invention is not limited to this, and all the vibration elements 16a to 16n are connected together. Alternatively, the section may be further subdivided. It is also possible to arrange the vibration elements 16a to 16n at unequal intervals.

  FIG. 4 is a longitudinal sectional view of one vibration element 16 in the vibration element 16 a to 16 n provided on the substrate 15 and the substrate 15 in FIG. 3. As shown in FIG. 4, the vibration element 16 includes a vibration film 20 provided to face the substrate 15, an electrode 17 a provided so as to be embedded in the vibration film 20, and the vibration film 20 and the substrate 15. And a support portion 22 that forms a vacuum or air space (hereinafter referred to as a space 21) and supports the vibrating membrane 20 on the substrate 15. An electrode 17b is provided below the substrate 15.

  The electrode 17a is connected to the drive signal power supply 26 of the transmission means 3 via a connection terminal 27a, and the electrode 17b is connected to the DC bias power supply 25 of the bias means 4 via a connection terminal 27b.

  Here, the substrate 15 is preferably formed of ceramics, glass, semiconductor, or the like. The vibration film 20 is preferably formed of a material having insulating properties and strength against repeated vibration, such as glass such as silicon nitride or ceramic, and the support portion 22 is similarly formed of silicon nitride. It is preferable that the insulating film is made of a material such as glass or ceramic that has an insulating property and a strength that supports the vibration film 20 on the substrate 15. Further, the electrodes 17a and 17b are preferably formed of a metal such as aluminum or titanium.

  Next, the operation of the vibration element 16 will be described. When a DC bias voltage is applied to the vibration element 16 by the DC bias power supply 25, an electric field is generated in the space 21 of the vibration element 16 according to the magnitude of the applied bias voltage. When the vibration film 20 is strained by the generated electric field, the value of the electromechanical coupling coefficient of the vibration element 16 is determined. When a drive signal is supplied from the drive signal power supply 26 to the vibration element 16, the supplied drive signal is converted into an ultrasonic wave based on the value of the electromechanical coupling coefficient. Further, when the ultrasonic wave reflected by the subject is received by the vibration element 16, the vibration film 20 of the vibration element 16 is excited based on the value of the electromechanical coupling coefficient. When the vibration film 20 is excited, the capacity of the space 21 is changed, and an electric signal based on the change in the capacity is taken into the ultrasonic diagnostic apparatus.

  Next, the vibration element of the ultrasonic probe 2 to which the present invention is applied will be described with reference to FIG. FIG. 5 is an enlarged view of the support portion 22 of the vibration element 16 in FIG. As shown in FIG. 5, the support portion 22 is provided with a plurality of low acoustic impedance portions 25, which are sound insulation portions that suppress ultrasonic waves that propagate between the vibration film 20 and the substrate 15, adjacent to the substrate 15. .

  In the present embodiment, the low acoustic impedance portion 25 is a vacuum or air space, but is not limited to this, and is a porous member in which a vacuum or air space is formed inside a metal, glass, ceramic, ferrite, or the like. There may be.

  Here, the overall configuration of the vibration element 16 in FIG. 5 will be described with reference to FIG. 6 is a cross-sectional view taken along line VI-VI of the vibration element 16 of FIG. As described above, the vibration element 16 is provided with the low acoustic impedance portion 25 over three layers so as to surround the outer periphery of the space 21, and each low acoustic impedance between the space 21 and the innermost low acoustic impedance portion 25. A support portion 22 is provided between the portions 25 on the outer peripheral side of the outermost low acoustic impedance portion 25. In addition, the low acoustic impedance part 25 is not limited to the example in which the low acoustic impedance part 25 is annularly arranged as in the present embodiment, and the annular low acoustic impedance part 25 is made into a plurality in consideration of the ability to suppress ultrasonic waves and the support strength of the support part 22. It can also be divided and arranged.

  Next, the operation and effect of the ultrasonic probe 2 of the present embodiment will be described. 7 to 10 are diagrams schematically showing a part of the cross section of the transducer 12 of the ultrasonic probe 2. Here, in FIG. 7 to FIG. 10, the four vibration elements on the left side are combined into the vibration element group 30, the two vibration elements on the right side are combined into the vibration element group 31, and the vibration element group 30 is driven simultaneously. A case where the vibration element group 31 is not driven will be described as an example.

  When the ultrasonic diagnostic apparatus 1 supplies a drive signal to the vibration film 20 of the vibration element group 30 and the electrodes 17a and 17b provided on the substrate 15, the vibration film 20 vibrates due to the drive signal and receives ultrasonic waves. A wave is transmitted in the specimen (in the direction of arrow 32 in FIG. 7). In addition, the vibration film 20 receives the ultrasonic wave reflected from the subject and vibrates. As shown in FIG. 7, the ultrasonic wave propagates in the direction of the arrow 33 through the support portion 22 due to the vibration of the vibration film 20 generated during such transmission / reception.

Here, when the ultrasonic wave travels from the medium A having the acoustic impedance Z ₁ (MRayls) to the medium B having the acoustic impedance Z ₂ (MRayls), the ratio R of the ultrasonic wave reflected at the boundary surface between the two media R (Reflectance) is expressed by the following equation.

(Formula 1)
R = | (Z ₁ −Z ₂ ) / (Z ₁ + Z ₂ ) |
In other words, when the ultrasonic wave travels from one medium to another, the reflectivity of the ultrasonic wave at the interface depends on the ratio of the acoustic impedance of both media, and the difference in the ratio of the acoustic impedance between the two media The larger the value, the more the ultrasonic wave is reflected at the interface between the two media.

  In this embodiment, the acoustic impedance of the support portion 22 formed of silicon nitride or the like is about 20 (MRayls), for example, and the acoustic impedance of the substrate 15 formed of silicon or the like is also about 20 (MRayls), for example. . On the other hand, since the low acoustic impedance unit 25 is vacuum or air, the acoustic impedance can be regarded as almost 0 (MRayls), for example, compared to the support unit 22 and the substrate 15. Therefore, as shown in FIG. 8, a part of the ultrasonic wave to be propagated from the vibration film 20 to the substrate 15 is caused by the acoustic impedance between the support portion 22 and the low acoustic impedance portion 25 provided below the support portion 22. Reflection in the direction of the arrow 34 due to the difference and the difference in acoustic impedance between the low acoustic impedance unit 25 and the substrate 15, the propagation of ultrasonic waves to the substrate 15 is suppressed. Thereby, generation | occurrence | production of the plate wave by the multiple reflection of the ultrasonic wave in the board | substrate 15 is suppressed.

  However, since the ultrasonic wave propagating to the substrate 15 cannot be completely suppressed, as shown in FIG. 9, the ultrasonic wave is multiple-reflected inside the substrate 15 to generate a plate wave as shown by an arrow 35 or the like. This plate wave tends to propagate to each vibration element of the vibration element group 30 and each vibration element of the vibration element group 31. However, for the same reason as described above, as shown in FIG. 10, the difference in acoustic impedance between the substrate 15 and the low acoustic impedance portion 25 provided below each support portion 22, and the low acoustic impedance portion 25 and the support portion 22. Reflected in the direction of arrow 36 due to the difference in acoustic impedance. Therefore, by driving the vibration element group 30, it is possible to suppress unnecessary vibration from being generated in the vibration film of the vibration element group 31 that is not driven.

  In this embodiment, the case where the vibration element group 30 is driven simultaneously and the vibration element group 31 is not driven has been described as an example. However, for example, the vibration element group 30 is driven with the vibration element to be driven. When there is no vibration element, the ultrasonic wave caused by the vibration of the driving vibration element is prevented from propagating to the vibration element that is not driven.

  According to the present embodiment, the generation of the plate wave is suppressed, and the plate wave generated without being suppressed is suppressed from propagating to the vibration film of the adjacent vibration element. Interference generated between elements can be suppressed.

  Moreover, since the vibration element of the ultrasonic probe 2 of the present embodiment is provided with the space 21 and the low acoustic impedance portion 25 in the same layer, the manufacturing man-hour can be reduced and the development cost can be suppressed. Can do.

  In this embodiment, the low acoustic impedance unit 25 is divided into a plurality of parts and provided adjacent to the substrate 15. However, the low acoustic impedance unit 25 transmits ultrasonic waves that propagate between the vibration film 20 and the substrate 15. Since it is provided for the purpose of suppression, it can be integrated without being divided into a plurality of parts, and the arrangement position is not limited. However, if the low acoustic impedance portion 25 is extremely large, the volume of the support portion 22 that supports the vibration film 20 on the substrate 15 becomes small, and the support strength cannot be maintained. Therefore, the low acoustic impedance unit 25 may be provided by appropriately determining the size and interval in consideration of the ability to suppress ultrasonic propagation and the support strength. For example, as shown in FIG. 11, it is also possible to provide the low acoustic impedance unit 25 in a multilayer shape, and to provide the lower low acoustic impedance unit 25 and the upper low acoustic impedance unit 25 alternately. According to such a configuration, it is possible to increase the ability to suppress ultrasonic propagation while maintaining the support strength of the support portion 22.

  A second embodiment of the present invention will be described with reference to FIGS. The only difference from the ultrasonic probe 2 of the first embodiment is that a sound absorbing portion is provided in place of the low acoustic impedance portion 25 provided in the support portion 22, and the description of the overlapping portion is omitted. FIG. 12 is an enlarged view of the cross section of the support portion 22 of the vibration element 16 of FIG. 4 and its peripheral members. As shown in FIG. 12, the sound absorbing portion 39 is not provided adjacent to the substrate 15 but is provided inside the support portion 22.

  The sound absorbing portion 39 is a member in which a plurality of spaces such as air or vacuum are mixed in a multi-layered and labyrinth-like manner in a member such as metal, glass, ceramic, and ferrite, or such a member is made of tungsten or platinum. A member in which powders of substances having different acoustic characteristics such as metal powder are mixed is preferable.

  Next, the operation of the ultrasonic probe 1 of the present embodiment will be described with reference to FIG. Here, the case where the member which mixed the tungsten powder 41 in the silicon nitride 40 is used as the sound absorption part 39 is demonstrated to an example. As in the first embodiment, when the vibration film 20 vibrates during transmission / reception of ultrasonic waves, the ultrasonic waves propagate to the support portion 22 and enter the sound absorbing portion 39 as indicated by an arrow 42. When the ultrasonic wave incident on the sound absorbing part 39 is incident on the tungsten powder 41 inside the sound absorbing part 39, it is reflected and scattered in all directions as shown in the figure. While such scattering is repeated inside the sound absorbing portion 39, the mechanical energy of the ultrasonic waves is converted into thermal energy, and as a result, the ultrasonic waves are absorbed inside the sound absorbing portion 39. That is, the ultrasonic wave incident on the sound absorbing portion 39 is substantially attenuated.

  Thereby, it can suppress that an ultrasonic wave propagates to the board | substrate 15, and can suppress generation | occurrence | production of a plate wave. Similarly to the first embodiment, the ultrasonic waves propagated to the substrate 15 without being able to be suppressed are multiple-reflected to generate a plate wave and try to propagate from the substrate 15 to the adjacent vibration element. Since the sound is absorbed in the same manner as described above, it is possible to suppress the plate wave propagating to the vibration film of the adjacent vibration element.

  The effect of suppressing the propagation of ultrasonic waves according to the present embodiment increases as the thickness of the sound absorbing portion 39 increases. Therefore, not only the arrangement of the sound absorbing portion 39 as in the present embodiment, for example, the entire support portion 22 can be formed by the sound absorbing portion 39 or can be formed in a multilayer shape.

  A third embodiment of the present invention will be described with reference to FIG. The difference from the ultrasonic probe 2 of the first embodiment is only the configuration of the low acoustic impedance part 25 and the sound absorbing part 39 inside the support part 22, and therefore the description of the overlapping parts is omitted. FIG. 14 is an enlarged view of the cross section of the support portion 22 and its peripheral members of the vibration element 16 of FIG. The present embodiment is a combination of the first embodiment and the second embodiment. Specifically, as shown in FIG. 14, the low acoustic impedance unit 25 described in the first embodiment is provided adjacent to the substrate 15. The sound absorbing portion 39 described in Example 2 is provided inside the support portion 22. That is, the low acoustic impedance unit 25 and the sound absorbing unit 39 are provided inside the support unit 22 along the propagation direction of the ultrasonic wave or the plate wave.

  According to the present embodiment, it is possible to more effectively suppress the ultrasonic wave or the plate wave propagating through the inside of the support portion 22, and it is possible to more effectively prevent the interference generated between the adjacent vibration elements due to the vibration of the vibration film. Can be suppressed.

  A fourth embodiment of the present invention will be described with reference to FIGS. The difference from the ultrasonic probe 1 of the first embodiment is only that the base film 45 is provided between the vibration element 16 and the substrate 15 and the position where the low acoustic impedance portion 25 is disposed. Is omitted. FIG. 15 is an enlarged view of the cross section of the vibration element 16, the base film 45, and the substrate 15 of the present embodiment. As shown in FIG. 15, the base film 45 is provided on the substrate 15, and the vibration element 16 is provided on the base film 45. The low acoustic impedance part 25 is provided in the base film 45 from the lower part of the support part 22 to the lower part of the space 21. Here, the base film 45 is preferably a member such as a glass such as silicon nitride or a ceramic, like the vibration film 20 and the support portion 22.

  According to the present embodiment, since the space 21 and the low acoustic impedance portion 25 are provided in different layers, the thickness of the space 21 and the thickness of the low acoustic impedance portion 25 can be made different or the shapes can be made different. In addition, as in the present embodiment, the space 21 and the low acoustic impedance unit 25 can be provided so as to partially overlap in the vertical direction. Thereby, since an ultrasonic wave and a plate wave can be made to enter into the low acoustic impedance part 25 more reliably, the interference which arises between adjacent vibration elements by the vibration of a vibration film can be suppressed more effectively.

  As described in the first embodiment, also in this embodiment, the shape, size, and arrangement position of the low acoustic impedance portion 25 are appropriately determined in consideration of the ability to suppress ultrasonic propagation and the support strength. Just decide.

  Further, as shown in FIG. 16, not only the low acoustic impedance portion 25 is provided on the base film 45 below the support portion 22 but also the low acoustic impedance portion 25 at a location where the vibration element 16 a of the base film 45 is not provided. By providing this, the acoustic impedance of the support portion 22 and the substrate 15 viewed from the subject side can be lowered. As a result, the acoustic impedance of the support 22 and the substrate 15 approaches that of the subject, so that the ultrasonic wave reflected from the subject (in the direction of arrow 48 in FIG. 16) is reflected by the support 22 and the substrate 15. Can be suppressed. That is, the acoustic impedance of the subject is about 1.5 (MRayls), for example, whereas the acoustic impedance of the support portion 22 and the substrate 15 is about 20 (MRayls). When not provided, as described in the first embodiment, the ultrasonic wave 48 reflected from the subject is almost reflected by the support portion 22 and the substrate 15 due to the difference in the ratio of the acoustic impedance. However, by providing the base film 45 as in the present embodiment, the ultrasonic wave reflected from the subject is reflected again not only at the place where the vibration element 16 is provided but also at the place where the vibration element 16 is not provided. Can be suppressed.

  Also in the first to third embodiments, similarly, the acoustic impedance of the support portion 22 viewed from the subject can be lowered to suppress the reflection of the ultrasonic wave reflected from the subject on the support portion 22.

1 is a diagram illustrating a configuration of an ultrasound probe and an ultrasound diagnostic apparatus in Embodiment 1. FIG. 1 is a perspective view of an ultrasonic probe in Example 1. FIG. 3 is an enlarged perspective view of a vibrator in Example 1. FIG. 2 is a longitudinal sectional view of a substrate of a vibrator and a vibration element provided on the substrate in Example 1. FIG. FIG. 3 is an enlarged view of a cross section of the supporting portion of the vibration element and the periphery thereof in the first embodiment. It is sectional drawing in the VI-VI line of the vibration element in FIG. FIG. 6 is a diagram for explaining an operation example of the ultrasonic probe in the first embodiment. FIG. 6 is a diagram for explaining an operation example of the ultrasonic probe in the first embodiment. FIG. 6 is a diagram for explaining an operation example of the ultrasonic probe in the first embodiment. FIG. 6 is a diagram for explaining an operation example of the ultrasonic probe in the first embodiment. FIG. 6 is a diagram illustrating an arrangement modification of the sound insulation portion of the vibration element in the first embodiment. FIG. 6 is an enlarged view of a cross section of a supporting portion of a vibration element and its periphery in Example 2. FIG. 10 is a diagram for explaining an operation example of an ultrasound probe in the second embodiment. FIG. 10 is an enlarged view of a cross section of a supporting portion of a vibration element and its periphery in Example 3. 10 is an enlarged view of a cross section of a vibration element, a base film, and a substrate in Example 4. FIG. FIG. 10 is a diagram for explaining an operation example of the ultrasonic probe according to the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus 2 Ultrasonic probe 12 Vibrator 15 Substrate 16 Vibrating element 20 Vibrating film 21 Space 22 Support part 25 Low acoustic impedance part 39 Sound absorbing part 41 Tungsten powder 45 Base film

Claims (6)

A plurality of transducers that mutually convert ultrasonic waves and electrical signals are arranged, and the transducer includes a substrate and a plurality of vibration elements provided on the substrate, and the vibration elements are disposed on the substrate. A vibration film provided; and a support part that supports the vibration film by forming a space between the vibration film and the substrate, and is provided between the vibration film and the substrate inside the support part. A sound insulation part that suppresses the ultrasonic wave propagating through the
The sound insulation part is a low acoustic impedance part having an acoustic impedance lower than any of the support part and the substrate,
The low acoustic impedance section, space, or metal, glass, ceramics, ultrasonic probe you being a porous member for a base material of ferrite. A plurality of transducers that mutually convert ultrasonic waves and electrical signals are arranged, and the transducer includes a substrate and a plurality of vibration elements provided on the substrate, and the vibration elements are disposed on the substrate. A vibration film provided; and a support part that supports the vibration film by forming a space between the vibration film and the substrate, and is provided between the vibration film and the substrate inside the support part. A sound insulation part that suppresses the ultrasonic wave that propagates is provided,
The sound insulating part is a sound absorbing part that absorbs the ultrasonic waves,
The sound absorbing unit, metal, glass, ceramic, porous member, or the ultrasound probe it characterized in that the porous member is a member obtained by mixing a metal powder as a base material of ferrite. The sound insulation part, the ultrasonic probe according to claim 1 or 2, characterized in that provided adjacent to the substrate.   A plurality of transducers that mutually convert ultrasonic waves and electrical signals are arranged, and the transducer includes a substrate and a plurality of vibration elements provided on the substrate, and the vibration elements are disposed on the substrate. A vibration film provided, and a support part that supports the vibration film by forming a space between the vibration film and the substrate, the support part on the substrate side inside the support part, A low acoustic impedance part having an acoustic impedance lower than any of the substrates is provided, and the inside of the support part and on the side facing the substrate of the low acoustic impedance part, between the vibration film and the substrate An ultrasonic probe comprising a sound absorbing portion that absorbs an ultrasonic wave propagating through the sound wave. A plurality of transducers that mutually convert ultrasonic waves and electrical signals are arranged. The transducer includes a substrate, a base film provided on the substrate, and a plurality of vibration elements provided on the base film. And the vibration element includes a vibration film provided on the base film, and a support part that supports the vibration film by forming a space between the vibration film and the base film. Inside the film, a sound insulation part for suppressing ultrasonic waves propagating between the vibration film and the substrate is provided,
The sound insulation portion is provided in a portion sandwiched between the support portion of the base film and the substrate, and an end portion of the sound insulation portion is formed in a lower portion of a space formed between the vibration film and the base film. ultrasonic probe you characterized by comprising been extended to. 6. The ultrasonic probe according to claim 1, transmission means for supplying a drive signal to the ultrasonic probe, and a DC bias voltage applied to the drive signal supplied to the ultrasonic probe. A biasing means for superimposing, a receiving means for performing a receiving process on the reflected echo signal output from the ultrasonic probe, and a phasing and an adding process for the reflected echo signal output from the receiving means An adding means, an image processing means for forming an ultrasonic image based on a reflected echo signal output from the phasing and adding means, and a display means for displaying the ultrasonic image output from the image processing means. Ultrasound diagnostic device.

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