JP2017183867A - Ultrasonic transducer, ultrasonic array, ultrasonic module, ultrasonic measurement apparatus, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic transducer which can increase a transmission frequency while suppressing a reduction in transmission output, and an ultrasonic array, an ultrasonic module, an ultrasonic measurement apparatus and an electronic apparatus.SOLUTION: An ultrasonic transducer comprises: a flexible membrane; and a first vibration section and a second vibration section for vibrating the flexible membrane. The second vibration section is provided at a position separated from a maximum displacement point of the flexible membrane in a plan view in a thickness direction of the flexible membrane.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an ultrasonic transducer, an ultrasonic array, an ultrasonic module, an ultrasonic measurement device, and an electronic apparatus.

  Conventionally, an ultrasonic sensor element including a diaphragm and a piezoelectric body and two electrodes sandwiching the piezoelectric body provided on one surface side of the diaphragm is known (for example, Patent Document 1). The ultrasonic sensor element described in Patent Literature 1 outputs an electrical signal corresponding to the vibration amplitude of a diaphragm by ultrasonic waves from two electrodes. Using this electrical signal, ultrasonic waves can be detected.

JP 2006-319945 A

  By the way, in an ultrasonic sensor element (hereinafter also referred to as an ultrasonic transducer) as described in Patent Document 1, for example, a rectangular wave voltage of a predetermined frequency is applied between two electrodes to vibrate the piezoelectric body. Thus, the diaphragm can be vibrated to transmit ultrasonic waves. Thus, the internal structure of the object can be measured by transmitting the ultrasonic wave from the ultrasonic transducer to the object and receiving the ultrasonic wave reflected from the object.

  Here, it is possible to improve the measurement accuracy by increasing the frequency of ultrasonic waves output from the ultrasonic transducer (hereinafter also referred to as transmission frequency) and improving the resolution. Specifically, in order to increase the transmission frequency, for example, it is conceivable to reduce the planar dimension of the diaphragm and increase the natural frequency of the diaphragm.

  However, when the planar dimension of the diaphragm is reduced, the maximum amplitude of the diaphragm when the ultrasonic transducer is driven to vibrate the diaphragm is reduced, and the area of the diaphragm is also reduced. Therefore, there is a possibility that the sound pressure, that is, the transmission output of the ultrasonic wave transmitted from the ultrasonic transducer is lowered. Thus, in the conventional ultrasonic transducer, there is a problem that it is not easy to increase the transmission frequency while suppressing a decrease in transmission output.

  One object of the present invention is to provide an ultrasonic transducer, an ultrasonic array, an ultrasonic module, an ultrasonic measurement device, and an electronic apparatus that can increase a transmission frequency while suppressing a decrease in transmission output. And

  An ultrasonic transducer according to an application example includes a flexible film, and a first vibrating part and a second vibrating part that vibrate the flexible film, and the second vibrating part has a thickness of the flexible film. It is provided at a position away from the maximum displacement point of the flexible film in a plan view as viewed from the direction.

The ultrasonic transducer of this application example includes a first vibrating portion and a second vibrating portion that vibrate the flexible membrane. The second vibrating portion is provided at a position away from the maximum displacement point of the flexible film in the plan view. Note that the maximum displacement point of the flexible membrane is the point at which the amount of displacement during free vibration is maximized. When the flexible membrane is formed uniformly along the surface direction, it coincides with the center of gravity of the flexible membrane.
When transmitting ultrasonic waves using this ultrasonic transducer, the first vibration unit applies stress to the flexible film to deform the flexible film in one direction, and the second vibration unit applies the flexible film to the flexible film. The natural frequency of the ultrasonic transducer can be increased by driving the first vibration unit and the second vibration unit so as to apply a stress to the flexible film in a direction opposite to the one direction. The frequency (transmission frequency) of the transmitted ultrasonic wave can be increased. That is, the second vibrating part applies stress in the opposite direction to the first vibrating part to a position away from the maximum displacement point of the flexible membrane, so that when the first vibrating part is driven alone, Compared to an ultrasonic transducer including only the membrane and the first vibration unit, the vibration period of the flexible membrane can be increased, and the natural frequency of the ultrasonic transducer can be increased.
When the planar dimension of the flexible membrane is reduced in advance to increase the natural frequency, the maximum amplitude of the flexible membrane and the area of the flexible membrane are reduced, so that the ultrasonic transmission output is reduced. On the other hand, in this application example, since it is not necessary to reduce the planar dimension of the flexible film, the transmission output is not reduced by reducing the planar dimension of the flexible film.
As described above, in this application example, it is possible to increase the transmission frequency while suppressing a decrease in the transmission output of the ultrasonic transducer.

In the ultrasonic transducer according to this application example, it is preferable that the first vibration unit is provided at a position overlapping the maximum displacement point in the plan view.
In this application example, the first vibration unit is provided at a position overlapping the maximum displacement point of the flexible membrane. Thereby, the flexible membrane can be efficiently vibrated by the first vibrating portion. Therefore, the transmission output of the ultrasonic transducer can be improved.

In the ultrasonic transducer of this application example, the first vibration unit is provided at a position that is point-symmetric with respect to the maximum displacement point in the plan view, and the second vibration unit is in the plan view. It is preferable to be provided at a position that is point-symmetric with respect to the maximum displacement point.
In this application example, the first vibrating portion and the second vibrating portion are provided at positions that are point-symmetric with respect to the maximum displacement point of the flexible film in plan view. In such a configuration, by vibrating the flexible film with the maximum displacement point of the flexible film as the center of vibration, the flexible film can be vibrated more efficiently, and the transmission output of the ultrasonic transducer is improved. be able to.

In the ultrasonic transducer according to this application example, it is preferable that the second vibration unit is provided along an outer edge of the flexible film in the plan view.
In this application example, the second vibrating portion is provided along the outer edge of the flexible membrane. In such a configuration, the second vibrating portion can be arranged at a position further away from the maximum displacement point of the flexible membrane. Therefore, it is possible to suppress the vibration of the flexible film around the maximum displacement point from being hindered by the second vibrating portion, and it is possible to suppress a decrease in the transmission output of the ultrasonic transducer.

In the ultrasonic transducer according to this application example, the first vibration unit is a first piezoelectric element provided on one surface of the flexible film, and the second vibration unit is the other of the flexible film. The second piezoelectric element is preferably provided on the surface.
In this application example, the first vibration unit is a first piezoelectric element, and the second vibration unit is a second piezoelectric element. The first piezoelectric element is provided on one surface of the flexible film, and the second piezoelectric element is provided on the second surface of the flexible film. In such a configuration, when a voltage is applied to each piezoelectric element, there is a difference in the amount of contraction between the surface of the piezoelectric body on the side of the flexible film and the surface on the opposite side, and each piezoelectric element is transferred to the flexible film. On the other hand, the opposite stress acts. As a result, the vibration period of the flexible membrane can be increased as described above, and the natural frequency can be increased while suppressing a decrease in the transmission output of the ultrasonic transducer.
In addition, since the second piezoelectric element is provided on the surface of the flexible film opposite to the surface on which the first piezoelectric element is provided, compared to the configuration provided on the same surface of the flexible film, It is easy to form each piezoelectric element.

In the ultrasonic transducer of this application example, the first piezoelectric element has a configuration in which a first electrode, a first piezoelectric body, and a second electrode are stacked from the flexible film side, and the second piezoelectric element Has a configuration in which a third electrode, a second piezoelectric body, and a fourth electrode are laminated from the flexible membrane side, and one of the first electrode and the second electrode, the third electrode, and the second electrode Preferably, one of the four electrodes is short-circuited, and the other of the first electrode and the second electrode and the other of the third electrode and the fourth electrode are short-circuited.
In this application example, one and the other of the electrodes of the first piezoelectric element and the second piezoelectric element are short-circuited. In such a configuration, when the ultrasonic transducer is driven, the first piezoelectric element and the second piezoelectric element can be driven with the same drive signal. Therefore, it is easier to synchronize the drive timing of each piezoelectric element as compared to a configuration in which each piezoelectric element is driven individually. Further, the configuration of the driving circuit of the ultrasonic transducer can be simplified as compared with the case where each piezoelectric element is driven individually. In addition, the processing load on the control device that controls the ultrasonic transducer and the drive circuit can be reduced.

An ultrasonic array of an application example is an ultrasonic array including a plurality of ultrasonic transducers including a flexible film, and a first vibration unit and a second vibration unit that vibrate the flexible film, The two vibrating portions are provided at positions away from the maximum displacement point of the flexible membrane in a plan view as viewed from the thickness direction of the flexible membrane.
The ultrasonic array of this application example includes a plurality of ultrasonic transducers of the above application example. Therefore, in this application example, similarly to the ultrasonic transducer of the application example described above, it is possible to increase the transmission frequency while suppressing a decrease in transmission output.

In the ultrasonic array of this application example, the first ultrasonic transducer and the second ultrasonic transducer among the plurality of ultrasonic transducers are arranged in the second vibration unit in the plan view. It is preferable that the areas of the formed regions are different.
In this application example, the plurality of ultrasonic transducers constituting the ultrasonic array include a first ultrasonic transducer and a second ultrasonic transducer having different areas of the second vibration part in the planar view. Including. The first ultrasonic transducer and the second ultrasonic transducer have different areas of the second vibration part, and the magnitude of stress applied to the flexible film from the second vibration part and stress are applied. The area is different. For this reason, the first ultrasonic transducer can transmit ultrasonic waves having a frequency different from that of the second ultrasonic transducer. Therefore, the ultrasonic array can transmit ultrasonic waves having two or more frequencies.

An ultrasonic module of one application example includes a flexible film, a first vibration part and a second vibration part that vibrate the flexible film, and a circuit board to which the first vibration part and the second vibration part are connected. The second vibrating section is provided at a position away from the maximum displacement point of the flexible film in a plan view as viewed from the thickness direction of the flexible film.
The ultrasonic module of this application example includes a first vibrating portion and a second vibrating portion that vibrate the flexible membrane. The flexible membrane has a maximum displacement point when vibrated by the first vibrating portion in the plan view, and the second vibrating portion is located away from the maximum displacement point of the flexible membrane in the plan view. Is provided. Therefore, in this application example, similarly to the ultrasonic transducer of the application example described above, it is possible to increase the transmission frequency while suppressing a decrease in transmission output.

The ultrasonic measurement apparatus according to this application example includes an ultrasonic transducer including a flexible film, and a first vibration unit and a second vibration unit that vibrate the flexible film, and the ultrasonic transducer generates ultrasonic waves. A transmitting unit that transmits the ultrasonic wave, and a receiving unit that receives the ultrasonic wave, and the second vibrating unit from a maximum displacement point of the flexible film in a plan view as viewed from the thickness direction of the flexible film. It is provided in a distant position.
The ultrasonic measurement apparatus of this application example includes the ultrasonic transducer of the above application example and a receiving unit that receives ultrasonic waves, and receives ultrasonic waves transmitted from the ultrasonic transducers, that is, ultrasonic measurement. Can be implemented. In this application example configured as described above, by using the ultrasonic transducer of the above application example, it is possible to increase the transmission frequency, that is, to improve the resolution while suppressing the decrease in the transmission output as described above. It is possible to carry out highly accurate ultrasonic measurement.

An electronic apparatus according to this application example includes an ultrasonic transducer including a flexible film, a first vibration unit and a second vibration unit that vibrate the flexible film, and a control unit that controls the ultrasonic transducer. The second vibrating section is provided at a position away from the maximum displacement point of the flexible film in a plan view as viewed from the thickness direction of the flexible film.
An electronic apparatus according to this application example includes the ultrasonic transducer according to the application example described above and a control unit that controls the ultrasonic transducer. In this application example configured as described above, by using the ultrasonic transducer of the application example described above, it is possible to increase the transmission frequency while suppressing the decrease in the transmission output as described above. Therefore, when performing ultrasonic measurement by receiving the ultrasonic wave transmitted from the ultrasonic transducer, it is possible to improve the resolution while suppressing a decrease in transmission output, and it is possible to perform highly accurate ultrasonic measurement.

The perspective view which shows schematic structure of the ultrasonic measuring device of 1st embodiment. 1 is a block diagram showing a schematic configuration of an ultrasonic measurement apparatus according to a first embodiment. The top view which shows schematic structure of the ultrasonic device in the ultrasonic probe of 1st embodiment. The top view which looked at the element board | substrate of the transmission unit of 1st embodiment from the opposite side to the sealing board. Sectional drawing which shows the transmission unit of 1st embodiment typically. The top view which looked at the element board | substrate of the transmission unit of 1st embodiment from the sealing board side. The figure which shows typically operation | movement of the transducer for transmission of 1st embodiment. The figure which shows the relationship between the width | variety of a 2nd piezoelectric element of a transducer for transmission, and a natural frequency. The figure which shows the relationship between the width | variety and displacement amount of the 2nd piezoelectric element of a transducer for transmission. The figure which shows the relationship between the natural frequency and displacement amount of a transducer for transmission. The top view which looked at the element board | substrate of the receiving unit of 1st embodiment from the opposite side to the sealing board. Sectional drawing which shows the receiving unit of 1st embodiment typically. The top view which looked at the element board | substrate of the transmission unit of 2nd embodiment from the sealing plate side. Sectional drawing which shows typically the transmission unit of 3rd embodiment. The block diagram which shows schematic structure of the ultrasonic measuring device which concerns on one modification of 3rd embodiment. Sectional drawing which shows typically the transmission unit which concerns on a modification. Sectional drawing which shows typically the transmission unit which concerns on a modification. Sectional drawing which shows typically the transmission unit which concerns on a modification.

[First embodiment]
Hereinafter, an ultrasonic measurement device as an electronic apparatus according to a first embodiment of the present invention will be described with reference to the drawings.
The ultrasonic measurement apparatus 1 of the present embodiment corresponds to the ultrasonic measurement apparatus of the present invention, and is electrically connected to the ultrasonic probe 2 and the ultrasonic probe 2 via a cable 3 as shown in FIG. The control device 10 is provided.
The ultrasonic measurement apparatus 1 causes an ultrasonic probe 2 to abut on the surface of a living body (for example, a human body), and transmits ultrasonic waves from the ultrasonic probe 2 into the living body. In addition, the ultrasonic wave reflected by the organ in the living body is received by the ultrasonic probe 2, and based on the received signal, for example, an internal tomographic image in the living body is obtained, or the state of the organ in the living body (for example, Blood flow etc.).

[Configuration of ultrasonic probe]
FIG. 3 is a plan view showing a schematic configuration of the ultrasonic sensor 24 in the ultrasonic probe 2.
The ultrasonic probe 2 includes a housing 21, an ultrasonic device 22 provided inside the housing 21, and a circuit board 23 provided with a driver circuit and the like for controlling the ultrasonic device 22. . The ultrasonic device 22 and the circuit board 23 constitute an ultrasonic sensor 24, and the ultrasonic sensor 24 constitutes an ultrasonic module of the present invention.

[Case configuration]
As shown in FIG. 1, the housing 21 is formed, for example, in a box shape having a rectangular shape in plan view, and a sensor window 21 </ b> B is provided on one surface (sensor surface 21 </ b> A) orthogonal to the thickness direction. A part of is exposed. Further, a passage hole 21C of the cable 3 is provided in a part (side surface in the example shown in FIG. 1) of the housing 21, and the cable 3 is connected to the circuit board 23 inside the housing 21 through the passage hole 21C. ing. Further, the gap between the cable 3 and the passage hole 21 </ b> C is ensured to be waterproof, for example, by being filled with a resin material or the like.
In the present embodiment, a configuration example in which the ultrasonic probe 2 and the control device 10 are connected using the cable 3 is shown, but the present invention is not limited to this. For example, the ultrasonic probe 2 and the control device 10 are wirelessly connected. They may be connected by communication, and various configurations of the control device 10 may be provided in the ultrasonic probe 2.

[Configuration of ultrasonic device]
As shown in FIG. 3, the ultrasonic device 22 includes a transmission unit TU corresponding to a transmission unit that transmits ultrasonic waves, and a reception unit RU corresponding to a reception unit that receives ultrasonic waves. Each of the transmission unit TU and the reception unit RU is mounted on the circuit board 23 (see FIG. 3), and is connected to the selection circuit 231 of the circuit board 23 as shown in FIG. The ultrasonic device 22 transmits ultrasonic waves from the transmission unit TU toward the living body. Further, the ultrasonic device 22 receives the ultrasonic waves reflected in the living body by the receiving unit RU.

[Configuration of transmission unit]
FIG. 4 is a plan view of the element substrate 41 of the transmission unit TU as viewed from the acoustic lens 44 side. FIG. 5 is a cross-sectional view schematically showing a cross section along the YZ plane of the transmission unit TU. 5 shows a cross section at a position passing through the center of gravity O of the flexible film 412A described later. FIG. 6 is a plan view of the element substrate 41 of the transmission unit TU as viewed from the sealing plate 42 side.
As shown in FIG. 5, the transmission unit TU includes an element substrate 41, a sealing plate 42, an acoustic matching layer 43, and an acoustic lens 44. In the present embodiment, the acoustic lens 44 is provided across the transmission unit TU and the reception unit RU, but may be provided in each of the transmission unit TU and the reception unit RU.

As shown in FIG. 4, the transmission unit TU is an ultrasonic transducer, and is a transmission ultrasonic array in which a plurality of transmission transducers 45 that transmit ultrasonic waves are arranged in a matrix. It has an array TA. The transmission array TA has a one-dimensional array structure in which a plurality of transmission channels (transmission transducer groups 45A described later) that are individually driven and transmit ultrasonic waves are arranged along one direction (scanning direction).
In the following description, the scan direction is the X direction, and the slice direction orthogonal to the scan direction is the Y direction. Further, the transmission direction of the ultrasonic waves of each transmission transducer 45 of the transmission unit TU is defined as the Z direction.

The element substrate 41 includes a substrate body 411 and a vibration film 412 provided on the −Z side of the substrate body 411. The central region of the element substrate 41 is a transmission array region Ar1 where the transmission array TA is formed.
The substrate body 411 is a semiconductor substrate such as Si. As shown in FIG. 4, the substrate body 411 is provided along the Y direction on the outer periphery of the element substrate 41 on the ± X side, and supports the vibration film 412. In FIG. 4, only the −X side is shown.

As shown in FIG. 5, the vibration film 412 closes each of the plurality of concave grooves 421 provided in the sealing plate 42 described later. A portion of the vibrating membrane 412 that closes the concave groove 421 constitutes an elastically deformable flexible membrane 412A. The flexible film 412A is formed at a position corresponding to each of the plurality of concave grooves 421. That is, the flexible film 412 </ b> A has a shape corresponding to the opening shape of the concave groove 421 in a plan view viewed from the Z direction.
As will be described later, the first piezoelectric element 451 is disposed on the + Z side surface (corresponding to one surface) of the flexible film 412A, and the second piezoelectric element 455 is disposed on the −Z side surface (corresponding to the other surface). , Provided. In the present embodiment, a transmission transducer 45 is configured including a flexible film 412A, a first piezoelectric element 451, and a second piezoelectric element 455.

In the present embodiment, as shown in FIG. 5, the vibration film 412 includes a first layer 413, a second layer 414, and a third layer 415. Among these, the first layer 413 is located on the + Z side of the vibration film 412 and is a layer on which the first piezoelectric element 451 is formed. The third layer 415 is a layer on the −Z side and on which the second piezoelectric element 455 is formed. The first layer 413 and the third layer 415 are made of, for example, ZrO ₂ . Incidentally, the first layer 413 and third layer 415, for _{example, Y 2 O 3, TiO 2} , HfO 2, V 2 O 5, Nb 2 O 5, Ta 2 O 5, WO transition metal oxides such as ₃ Ya , AlN, TiN, Si ₂ N ₄ , and other various insulating materials may be used.
The second layer 414 is disposed between the first layer 413 and the second layer 414, and is made of, for example, SiO ₂ or the like. When the substrate body 411 is made of Si and the second layer 414 is made of SiO ₂ , for example, the second layer 414 can be easily formed by thermally oxidizing the substrate body 411. .

(Transmission array configuration)
As described above, the transmission array TA includes a plurality of transmission transducers 45 arranged in a matrix. The transmission array TA includes a plurality of transmission transducers 45 arranged along the X direction (slice direction), and includes a transmission transducer group 45A that functions as one transmission channel. Further, the transmission array TA is configured such that a plurality of transmission transducer groups 45A are arranged along the Y direction (scanning direction) and can be individually driven.

As shown in FIG. 5, the transmission transducer 45 is provided on the flexible film 412A, the first piezoelectric element 451 provided on the + Z side of the flexible film 412A, and the −Z side of the flexible film 412A. And a second piezoelectric element 455.
The first piezoelectric element 451 is configured by laminating a first lower electrode 452, a first piezoelectric film 453, and a first upper electrode 454 in order from the flexible film 412A side.
The second piezoelectric element 455 includes a second lower electrode 456, a second piezoelectric film 457, and a second upper electrode 458 stacked in order from the flexible film 412A side.
The transmission transducer 45 will be described in detail later.

  Here, as shown in FIG. 4, the first lower electrodes 452 of the first piezoelectric elements 451 are connected to each other in the plurality of transmission transducers 45 constituting the transmission transducer group 45 </ b> A. Specifically, the first lower electrodes 452 of the transmitting transducers 45 adjacent along the Y direction are connected to each other by the first lower electrode line 452A. Further, the first lower electrodes 452 of the transmitting transducers 45 arranged at both ends in the Y direction are first lower portions formed in the terminal area Ar2 outside the transmission array area Ar1 by the first lower lead lines 452B. It is connected to the electrode pad 452P. The first lower electrode pad 452P is connected to the circuit board 23. In FIG. 4, only the first lower electrode pad 452P on the + Y side is shown.

  On the other hand, the first upper electrode 454 of the transmission transducer 45 is connected to the first upper electrode pad 454P formed in the terminal region Ar2 by the first upper electrode line 454A and the first upper lead line 454B. Specifically, the first upper electrodes 454 of the transmitting transducers 45 adjacent in the X direction are connected to each other by the first upper electrode line 454A. The first lower electrodes 452 of the transmitting transducers 45 disposed at both ends in the X direction are connected to the first upper lead line 454B by the first upper electrode line 454A. The first upper lead line 454B is drawn to the terminal region Ar2 along the Y direction, and is connected to the first upper electrode pad 454P. The first upper electrode pad 454P is connected to a ground circuit (not shown) of the circuit board 23. That is, the first upper electrode 454 of each first piezoelectric element 451 becomes the reference potential. In FIG. 4, only the first upper electrode pad 454P on the -X side is shown.

  As shown in FIG. 6, in the plurality of transmission transducers 45 constituting the transmission transducer group 45A, the second lower electrode 456 of the second piezoelectric element 455 is similar to the first lower electrode 452, The second lower electrode lines 456A are connected to each other, and the second lower electrode lines 456B are connected to a second lower electrode pad 456P formed in the terminal region Ar2. The second lower electrode pad 456P is connected to the circuit board 23. In FIG. 6, only the second lower electrode pad 456P on the + Y side is shown.

Similarly to the first upper electrode 454, the second upper electrode 458 is connected to the second upper electrode pad 458P formed in the terminal region Ar2 by the second upper electrode line 458A and the second upper lead line 458B. Yes. The second upper electrode pad 458P is connected to a ground circuit (not shown) of the circuit board 23. That is, the second upper electrode 458 of each second piezoelectric element 455 becomes the reference potential. In FIG. 6, only the −X side second upper electrode pad 458 </ b> P is illustrated.
In the transmission array TA configured as described above, the drive signal from the circuit board 23 is individually input to each of the plurality of transmission transducer groups 45A, so that each of the transmission transducer groups 45A individually Driven by.

(Configuration of sealing plate)
The sealing plate 42 is provided in order to reinforce the strength of the element substrate 41, and is configured by, for example, a semiconductor substrate or the like and bonded to the element substrate 41. Since the material and thickness of the sealing plate 42 affect the frequency characteristics of the transmitting transducer 45, it is preferable to set the sealing plate 42 based on the center frequency of the ultrasonic wave transmitted and received by the transmitting transducer 45.

The sealing plate 42 is provided with a concave groove 421 that opens to the + Z side at a position corresponding to each transmission transducer 45 in plan view. In addition, a region where the concave groove 421 is not formed serves as a suppression unit 422 that suppresses vibration of the vibration film 412.
In other words, the vibration film 412 is joined to the + Z side surface of the suppressing portion 422, and the respective concave grooves 421 are closed by the vibration film 412. In a plan view viewed from the Z direction, a portion surrounded by the inner peripheral surface of the groove 421 of the vibration film 412 is a flexible film 412A that can be elastically deformed. That is, the flexible film 412A has a shape corresponding to the opening shape of the concave groove 421 in a plan view viewed from the Z direction. Therefore, the natural frequency of the flexible film 412A can be adjusted according to the opening dimension (dimensions along the X direction and the Y direction) of the concave groove 421. That is, by reducing the opening size of the concave groove 421, the natural frequency of the flexible film 412A can be reduced, and as a result, the frequency (transmission frequency) of the ultrasonic wave transmitted from the transmission transducer 45 can be reduced. Conversely, by increasing the opening size of the concave groove 421, the natural frequency of the flexible film 412A can be increased, and as a result, the transmission frequency of the transmission transducer 45 can be increased.

  The concave groove 421 suppresses inconvenience (crosstalk) in which a back wave generated in one transmission transducer 45 due to the vibration of the flexible film 412A is propagated to another adjacent transmission transducer 45. Further, the groove depth of the concave groove 421 is set to be an odd multiple of one quarter (λ / 4) of the wavelength λ of the ultrasonic wave. Thereby, when the back wave reflected by the sealing plate 42 is input again to the transmitting transducer 45, it is emitted from the transmitting transducer 45 to the living body side (the side opposite to the sealing plate 42). A phase shift with the ultrasonic wave is suppressed, and attenuation of the ultrasonic wave is suppressed.

(Configuration of acoustic matching layer and acoustic lens)
As shown in FIG. 5, the acoustic matching layer 43 is provided on the surface of the element substrate 41 opposite to the sealing plate 42. Specifically, the acoustic matching layer 43 is filled between the element substrate 41 and the acoustic lens 44 and is formed with a predetermined thickness from the surface of the substrate body 411.
The acoustic lens 44 is provided on the acoustic matching layer 43, and is exposed to the outside from the sensor window 21B of the housing 21, as shown in FIG. The acoustic lens 44 has a cylindrical shape whose surface on the + Z side is curved along the Y direction (slice direction). Note that the surface on the + Z side of the acoustic lens 44 has different curvatures on the transmission unit TU side and the reception unit RU side. That is, the acoustic lens 44 has a curvature suitable for converging the ultrasonic wave transmitted from the ultrasonic device 22 at a predetermined distance in the Z direction on the transmission unit TU side. On the other hand, the acoustic lens 44 has a curvature suitable for converging the ultrasonic waves reflected in the living body to the reception array RA (see FIG. 11) on the reception unit RU side.

  The acoustic matching layer 43 and the acoustic lens 44 efficiently propagate the ultrasonic wave transmitted from the transmitting transducer 45 to the living body to be measured, and efficiently reflect the ultrasonic wave reflected in the living body to the receiving unit RU. To the receiving transducer 55. For this reason, the acoustic matching layer 43 and the acoustic lens 44 are set to an acoustic impedance intermediate between the acoustic impedance of the transducers 45 and 55 of the element substrate 41 and the acoustic impedance of the living body.

(Configuration of transducer for transmission)
Hereinafter, the transmission transducer 45 of the present embodiment will be described.
As shown in FIG. 5, the transmission transducer 45 includes a flexible film 412 </ b> A, a first piezoelectric element 451, and a second piezoelectric element 455.
As shown in FIG. 4, the flexible membrane 412A has a substantially rectangular outer shape in a plan view viewed from the Z direction. The flexible film 412A is formed substantially uniformly in the surface direction, and the center of gravity O coincides with the center in plan view. Further, the outer edge 412B of the flexible film 412A is fixed to the suppressing portion 422 of the sealing plate 42. Therefore, the flexible membrane 412A vibrates with the outer edge 412B as a fixed end in accordance with the driving of the piezoelectric elements 451 and 455. In the present embodiment, the point at which the displacement amount in the flexible film 412A is the maximum (maximum displacement point) coincides with the center of gravity O.

  The first piezoelectric element 451 corresponds to a first vibrating portion, and is provided on the first layer 413 side (+ Z side) of the flexible film 412A as shown in FIG. A lower electrode 452, a first piezoelectric film 453, and a first upper electrode 454 are stacked. Further, as shown in FIG. 4, the first piezoelectric element 451 has a point-symmetric shape with respect to the center of gravity O of the flexible film 412A in a plan view as viewed from the thickness direction of the flexible film 412A.

The first lower electrode 452 corresponds to the first electrode, and is formed in a substantially rectangular shape at a position overlapping the first upper electrode 454 in plan view as shown in FIG. The first lower electrode 452 is formed of a conductive electrode material such as Ir, Pt, IrOx, Ti, TiOx, for example.
The first piezoelectric film 453 corresponds to the first piezoelectric body, is formed in a substantially rectangular shape in plan view as shown in FIG. 4, and covers the first lower electrode 452. The first piezoelectric film 453 uses, for example, a transition metal oxide having a perovskite structure, more specifically, lead zirconate titanate (PZT) containing lead (Pb), titanium (Ti), and zirconium (Zr). Formed. By setting the composition ratio of Zr and Ti to 52:48, the first piezoelectric film 453 having good piezoelectric characteristics, that is, a particularly high piezoelectric constant (e constant) can be formed.
The first upper electrode 454 corresponds to a second electrode and is formed on the first piezoelectric film 453. Further, the first upper electrode 454 is formed in a substantially rectangular shape in plan view as shown in FIG. The first upper electrode 454 is made of the same electrode material as that of the first lower electrode 452.

The second piezoelectric element 455 corresponds to the second vibrating section, and is provided on the third layer 415 side (−Z side) of the flexible film 412A as shown in FIG. The two lower electrodes 456, the second piezoelectric film 457, and the second upper electrode 458 are laminated.
As shown in FIG. 6, the second piezoelectric element 455 is formed at a position away from the center of gravity O of the flexible film 412A in plan view. In the present embodiment, the second piezoelectric element 455 is formed in an annular shape that surrounds the center of gravity O and is point-symmetric with respect to the center of gravity O along the outer edge 412B of the flexible film 412A in plan view.

The second lower electrode 456 corresponds to a third electrode, and is formed in a substantially rectangular ring shape along the outer edge 412B of the flexible film 412A at a position overlapping the second upper electrode 458 in plan view, as shown in FIG. ing. The second lower electrode 456 is formed of the same electrode material as that of the first lower electrode 452.
The second piezoelectric film 457 corresponds to a second piezoelectric body, is formed in a substantially rectangular ring shape in plan view, and covers the second lower electrode 456 as shown in FIG. The second piezoelectric film 457 is made of the same material as the first piezoelectric film 453.
The second upper electrode 458 corresponds to a fourth electrode and is formed on the second piezoelectric film 457. Further, the second upper electrode 458 is formed in a substantially rectangular ring shape in plan view as shown in FIG. The second upper electrode 458 is formed of the same electrode material as that of the first lower electrode 452.

FIG. 7 is a diagram for explaining the operation of the transmission transducer 45.
The transmitting transducer 45 configured as described above has a rectangular shape with a predetermined frequency between the first lower electrode 452 and the first upper electrode 454 and between the second lower electrode 456 and the second upper electrode 458. By applying the wave voltage, the first piezoelectric film 453 and the second piezoelectric film 457 expand and contract in the in-plane direction. The piezoelectric films 453 and 457 are displaced in the film thickness direction and vibrate due to a difference in expansion / contraction amount between the flexible film 412A side and the opposite side. Due to the vibration of each of the piezoelectric films 453 and 457, the flexible film 412A is also vibrated and an ultrasonic wave is transmitted.

  Here, as shown in FIG. 7, in the transducer for transmission 45 of this embodiment, the vibration directions of the first piezoelectric film 453 and the second piezoelectric film 457 are opposite. That is, the first upper electrode 454 of the first piezoelectric element 451 and the second upper electrode 458 of the second piezoelectric element 455 are set to the reference potential. On the other hand, the first lower electrode 452 of the first piezoelectric element 451 and the second lower electrode 456 of the second piezoelectric element 455 are individual electrodes of the transmitting transducer 45. When the first piezoelectric element 451 and the second piezoelectric element 455 thus configured are driven by the same drive signal, the first lower electrode 452 and the first upper electrode 454, the second lower electrode 456, An electric field is applied between the second upper electrodes 458. Then, as shown in FIG. 7, the flexible film 412 </ b> A deforms in the reverse direction and vibrates at each formation position of the first piezoelectric element 451 and the second piezoelectric element 455.

Thereby, compared with the case where the second piezoelectric element 455 is not provided or the case where only the first piezoelectric element 451 is driven, the vibration period of the flexible film 412A can be increased, and the transmission frequency of the transmission transducer 45 can be increased. Can be increased.
Here, in order to increase the transmission frequency, it is conceivable to reduce the size of the flexible membrane 412A and increase the natural frequency of the flexible membrane 412A. In this case, however, the maximum displacement point ( In this embodiment, the displacement amount of the center of gravity O) and the area of the flexible film 412A are also reduced, and the transmission output is reduced. On the other hand, in the transmission transducer 45 of the present embodiment, since the dimension of the flexible film 412A is not changed, the transmission frequency can be increased while suppressing a decrease in transmission output.

FIG. 8 is a diagram showing the relationship between the width of the second piezoelectric element 455 and the natural frequency of the transmitting transducer 45. FIG. 9 is a diagram showing the relationship between the width of the second piezoelectric element 455 and the displacement amount (maximum displacement amount at the center of gravity O) of the flexible film 412A. FIG. 10 is a diagram showing the relationship between the natural frequency of the transmission transducer 45 and the amount of displacement of the flexible film 412A when the width of the second piezoelectric element 455 is changed.
Here, the width of the second piezoelectric element 455 refers to one side (Y of the annular second piezoelectric element 455) on a line passing through the center of gravity O along the short side direction (X direction in the present embodiment) of the flexible film 412A. Width along the direction).
8 to 9, the width along the short side direction of the flexible film 412A (that is, the width along the imaginary line passing through the center of gravity O and having the shortest distance between the intersections with the outer edge 412B). In the present embodiment, data D1 to data D3 when the width (W along the X direction) W is changed are shown. Specifically, data D1 is when the width W is 30 μm, data D2 is when the width W is 32.5 μm, and data D3 is when the width W is 35 μm. The width of the first piezoelectric element 451 in the X direction is 0.8 times the width W of the flexible film 412A (that is, 0.8 W). FIG. 10 shows data D4 when the width W of the flexible film 412A is changed without providing the second piezoelectric element 455 as a comparative example.
Further, each data indicates that the clearance between the outer edge 412B of the flexible film 412A and the first piezoelectric element 451 is C (that is, 0.1 W), and the width of the second piezoelectric element 455 is 0.2 C or more and 4.5 C. The case where a plurality of points in the following ranges are set is shown. That is, each data shows a case where the width of the second piezoelectric element 455 is set to a plurality of values in the range of 0.02 W or more and 0.45 W or less.

As shown in FIGS. 8 and 10, by providing the second piezoelectric element 455, the natural frequency of the transmitting transducer 45 increases. In any case, the natural frequency increases to about 1.5 times at the maximum.
In addition, in the range where the width of the second piezoelectric element 455 is 0.2 W (that is, 2C) or less, the natural frequency increases as the width of the second piezoelectric element 455 increases. For example, in the data D3 (when the width W of the flexible film 412A is 32.5 μm), the width of the second piezoelectric element 455 is in the range of 7 μm or less. Thus, by setting the width of the second piezoelectric element 455 within a range of 0.2 W or less, the natural frequency of the transmitting transducer 45 is increased, and the natural frequency is set according to the width of the second piezoelectric element 455. Can be set.

As shown in FIGS. 9 and 10, by providing the second piezoelectric element 455, the natural frequency of the transmitting transducer 45 is increased, and a decrease in the displacement amount of the flexible film 412A is suppressed.
In addition, in the range where the width of the second piezoelectric element 455 is 0.4 W (that is, 4C) or less, a decrease in the displacement amount of the flexible film 412A is more preferably suppressed. For example, in the data D3 (when the width W of the flexible film 412A is 32.5 μm), the width of the second piezoelectric element 455 is in the range of 14 μm or less. Furthermore, in the range where the width of the second piezoelectric element 455 is 0.2 W (that is, 2C) or more and 0.5 (that is, 5C) W or less, the decrease in the displacement amount of the flexible film 412A is more preferably suppressed. . That is, the width of the second piezoelectric element 455 is preferably 0.4 W or less, and more preferably in the range of 0.2 W or more and 0.5 W or less. As a result, the natural frequency of the transmission transducer 45 can be increased, and the displacement amount of the flexible film 412A, that is, the transmission output (transmission sensitivity) of the transmission transducer 45 can be suitably suppressed.

[Receiver configuration]
FIG. 11 is a plan view of the element substrate 51 of the receiving unit RU as viewed from the acoustic lens 44 side. FIG. 12 is a cross-sectional view schematically showing a cross section along the YZ plane of the receiving unit RU.
As shown in FIG. 12, the receiving unit RU includes an element substrate 51, a sealing plate 52, an acoustic matching layer 53, and the acoustic lens 44 described above. As described above, the acoustic lens 44 is provided across the transmission unit TU and the reception unit RU.
As shown in FIG. 11, the reception unit RU includes a reception array RA in which a plurality of reception transducers 55 capable of receiving the ultrasonic waves transmitted from the transmission unit TU are arranged in a matrix. In the present embodiment, the receiving array RA has a one-dimensional array structure in which a plurality of receiving channels (receiving transducer group 55A shown in FIG. 11) for receiving ultrasonic waves are arranged along the X direction (scanning direction). The configuration is exemplified, but the present invention is not limited to the one-dimensional array structure, and may have a two-dimensional array structure, and the number of receiving transducers 55 is not limited to the example shown in FIG.
In the following description, it is assumed that the receiving unit RU receives the ultrasonic wave propagated in the −Z direction by the receiving transducer 55.

The element substrate 51 includes a substrate body 511 and a vibration film 512 provided on the −Z side of the substrate body 511. The central region of the element substrate 51 is a reception array region Ar3 where the reception array RA is formed.
The substrate body 511 is a semiconductor substrate such as Si. In the reception array area Ar3 of the substrate body 511, openings 511A corresponding to the respective receiving transducers 55 are provided. The opening size of these openings 511A is a size based on the frequency of the ultrasonic wave transmitted from the transmission unit TU, as will be described later.
The vibration film 512 is made of, for example, SiO ₂ , a laminated body of SiO ₂ and ZrO ₂ , and is provided on the −Z side surface of the substrate body 511 and closes the opening 511A. A portion of the vibration film 512 that closes the opening 511A constitutes a flexible film 512A that can be elastically deformed.

A third piezoelectric element 551 is formed on the −Z side of the flexible film 512A, and the receiving transducer 55 is configured including the flexible film 512A and the third piezoelectric element 551. That is, in the receiving transducer 55, the flexible film 512A is vibrated by ultrasonic waves, and the third piezoelectric element 551 outputs an electrical signal corresponding to the vibration of the flexible film 512A.
Here, the receiving transducer 55 is configured to be able to detect ultrasonic waves (that is, ultrasonic waves to be detected) transmitted from the transmitting transducer 45 and reflected in the living body. For example, the flexible film 512 </ b> A and the third piezoelectric element 551 are configured so that the natural frequency of the receiving transducer 55 substantially matches the frequency of the ultrasonic wave to be detected. The flexible film 512A has a planar shape corresponding to the opening shape of the opening 511A. For example, by reducing the size of the opening 511A, the natural frequency of the flexible film 512A can be increased, and as a result, the natural frequency of the receiving transducer 55 can be increased.

The third piezoelectric element 551 of the receiving transducer 55 is configured by laminating a third lower electrode 552, a third piezoelectric film 553, and a third upper electrode 554 in order from the flexible film 512A side. Among these, the third lower electrode 552 and the third upper electrode 554 are formed of a conductive electrode material such as Ir, Pt, IrOx, Ti, and TiOx. The third piezoelectric film 553 is, for example, a transition metal oxide having a perovskite structure, more specifically, lead zirconate titanate (PZT) containing lead (Pb), titanium (Ti), and zirconium (Zr). It is formed using. By setting the composition ratio of Zr and Ti to 52:48, the third piezoelectric film 553 having good piezoelectric characteristics, that is, a particularly high piezoelectric constant (e constant) can be formed.
In the receiving transducer 55 configured as described above, when the flexible film 512A of the vibration film 512 is vibrated by the ultrasonic wave reflected from the object, a potential difference is generated between the upper and lower sides of the third piezoelectric film 553. As a result, a potential difference is generated between the third lower electrode 552 and the third upper electrode 554, and an electrical signal corresponding to the potential difference is output from the receiving transducer 55.

Here, as shown in FIG. 11, the plurality of receiving transducers 55 arranged along the Y direction constitute a receiving transducer group 55A which is one receiving channel. A plurality of receiving transducer groups 55A are arranged along the X direction to form a receiving array RA.
In the receiving transducer group 55A, the third lower electrode 552 and the third upper electrode 554 of the third piezoelectric element 551 are connected in the plurality of receiving transducers 55 constituting the receiving transducer group 55A. .
Specifically, the third lower electrodes 552 of the receiving transducers 55 adjacent in the Y direction are connected to each other by the third lower electrode line 552A. Further, the third lower electrode 552 of the receiving transducer 55 arranged at both ends in the Y direction is a third lower electrode pad 552P formed in the terminal area Ar4 outside the receiving array area Ar3 by the third lower lead line 552B. It is connected to. The third lower electrode pad 552P is connected to the circuit board 23.

  The third upper electrode 554 is connected to the third upper electrode pad 554P formed in the terminal region Ar4 by the third upper electrode line 554A and the third upper lead line 554B. Specifically, the third upper electrodes 554 of the receiving transducers 55 adjacent along the X direction are connected to each other by the third upper electrode line 554A. Further, the third upper electrode 554 of the receiving transducer 55 arranged at both ends in the X direction is connected to the third upper lead line 554B by the third upper electrode line 554A. The third upper lead line 554B is led out to the terminal region Ar4 along the Y direction, and is connected to the third upper electrode pad 554P. The third upper electrode pad 554P is connected to a ground circuit (not shown) of the circuit board 23.

  The sealing plate 52 is formed in the same shape as the element substrate 51, for example, when viewed from the thickness direction, and is composed of a metal plate such as alloy, a semiconductor substrate such as Si, and the like, and is bonded to the element substrate 51. ing. Since the material and thickness of the sealing plate 42 affect the frequency characteristics of the receiving transducer 55, it is preferable to set the sealing plate 42 based on the center frequency of the ultrasonic wave transmitted and received by the receiving transducer 55.

  The sealing plate 52 has a plurality of concave grooves 521 corresponding to the openings 511 </ b> A of the element substrate 51. The concave groove 521 is provided to suppress the influence of the back wave of the ultrasonic wave generated by the vibration of the flexible film 512A. That is, each concave groove 521 suppresses inconvenience (crosstalk) in which a back wave generated by one receiving transducer 55 is input to another adjacent receiving transducer 55 during reception of ultrasonic waves.

  The acoustic matching layer 53 is provided on the + Z side of the element substrate 51. Specifically, the acoustic matching layer 53 is filled in the opening 511A of the element substrate 51, and is formed with a predetermined thickness dimension from the bottom surface side of the opening 511A. The acoustic matching layer 53 is set to an intermediate acoustic impedance between the acoustic impedance of the receiving transducer 55 and the acoustic impedance of the living body.

[Configuration of circuit board]
The circuit board 23 is joined with the ultrasonic device 22 and is provided with a driver circuit and the like for controlling the transmission unit TU and the reception unit RU. As shown in FIG. 2, the circuit board 23 includes a selection circuit 231, a transmission circuit 232, a reception circuit 233, and a connector unit 234 (see FIG. 3).

The selection circuit 231 is connected to each electrode pad 452P, 454P, 456P, 458P of the transmission unit TU and each electrode pad 552P, 554P of the reception unit RU.
The selection circuit 231 switches between a transmission connection for connecting the ultrasonic sensor 24 and the transmission circuit 232 and a reception connection for connecting the ultrasonic sensor 24 and the reception circuit 233 based on the control of the control device 10.
In addition, the selection circuit 231 connects the transmission circuit 232 to the first lower electrode pad 452P and the second lower electrode pad 456P connected to the transmission transducer group 45A to be driven at the time of transmission connection. The first upper electrode pad 454P and the second upper electrode pad 458P of the transmission unit TU and the third upper electrode pad 554P of the reception unit RU are connected to, for example, a ground circuit (not shown) and set to a reference potential. Has been.

  When the transmission circuit 232 is switched to the transmission connection under the control of the control device 10, the transmission circuit 232 outputs a transmission signal for causing the ultrasonic sensor 24 to transmit an ultrasonic wave via the selection circuit 231. The transmission circuit 232 is controlled between the first lower electrode pad 452P and the first upper electrode pad 454P and between the second lower electrode pad 456P and the second upper electrode pad 458P based on the control from the control device 10. A voltage is applied to. As a result, an electric field in the opposite direction is applied between the first lower electrode 452 and the first upper electrode 454 and between the second lower electrode 456 and the second upper electrode 458, and the first piezoelectric element 451 and the second upper electrode 458 are applied. The piezoelectric element 455 is driven in the opposite direction.

  When the reception circuit 233 is switched to the reception connection under the control of the control device 10, the reception circuit 233 outputs the reception signal input from the ultrasonic sensor 24 via the selection circuit 231 to the control device 10. The reception circuit 233 includes, for example, a low-noise amplifier circuit, a voltage control attenuator, a programmable gain amplifier, a low-pass filter, an A / D converter, and the like. The reception circuit 233 converts the received signal into a digital signal, removes a noise component, and is desired. After performing each signal processing such as amplification to the signal level, the received signal after processing is output to the control device 10.

  The connector unit 234 is connected to the transmission circuit 232 and the reception circuit 233. Further, the cable 3 is connected to the connector portion 234, and as described above, the cable 3 is pulled out from the passage hole 21 </ b> C of the housing 21 and connected to the control device 10.

[Configuration of control device]
As illustrated in FIG. 2, the control device 10 includes, for example, an operation unit 11, a display unit 12, a storage unit 13, and a control unit 14. For example, the control device 10 may be a terminal device such as a tablet terminal, a smartphone, or a personal computer, or may be a dedicated terminal device for operating the ultrasonic probe 2.
The operation unit 11 is a user interface (UI) for the user to operate the ultrasonic measurement apparatus 1 and can be configured by a touch panel provided on the display unit 12, operation buttons, a keyboard, a mouse, or the like, for example. .
The display unit 12 is configured by a liquid crystal display, for example, and displays an image.
The storage unit 13 stores various programs and various data for controlling the ultrasonic measurement apparatus 1.
The control unit 14 includes an arithmetic circuit such as a CPU (Central Processing Unit) and a storage circuit such as a memory. The control unit 14 reads and executes various programs stored in the storage unit 13 to control the generation and output processing of the transmission signal for the transmission circuit 232 and the reception signal 233 for the reception circuit 233. Controls frequency setting and gain setting.

[Operational effects of the first embodiment]
The transmission transducer 45 of this embodiment includes a first piezoelectric element 451 and a second piezoelectric element 455 that vibrate the flexible film 412A. The first piezoelectric element 451 is disposed at a position overlapping the center of gravity O of the flexible film 412A, and the second piezoelectric element 455 can be positioned away from the center of gravity O, specifically, surrounding the center of gravity O. It arrange | positions along the outer edge 412B of the flexure film 412A. Each of these piezoelectric elements 451 and 455 applies a force for deforming the flexible film 412A in the opposite direction to the flexible film 412A. For this reason, the vibration period of the flexible film 412A can be increased as compared with the case where the first piezoelectric element 451 is driven alone or in the case where the second piezoelectric element 455 is not provided. The frequency, that is, the transmission frequency can be increased.

  In order to increase the natural frequency of the transmitting transducer 45, it is conceivable to reduce the planar dimension of the flexible film 412A in advance. However, in such a case, since the maximum amplitude of the flexible film 412A and the area of the flexible film 412A are reduced, the transmission output of the ultrasonic wave is reduced. Further, in order to reduce the flexible film 412A, it is necessary to reduce the planar dimension of the concave groove 421 formed in the sealing plate 42, but this also has a limit. On the other hand, in this embodiment, since it is not necessary to reduce the planar dimension of the flexible film 412A, there is no problem of a decrease in transmission output caused by reducing the planar dimension of the flexible film 412A.

  From the above, according to the configuration of the present embodiment, it is possible to increase the transmission frequency while suppressing a decrease in the transmission output of the transmission transducer 45. Similarly, in the transmission array TA and the transmission unit TU including a plurality of transmission transducers 45 as described above, it is possible to increase the transmission frequency while suppressing a decrease in transmission output. Furthermore, the resolution of the ultrasonic measurement apparatus 1 can be improved, and the measurement accuracy can be improved.

  In the present embodiment, the first piezoelectric element 451 and the second piezoelectric element 455 are provided at positions that are point-symmetric with respect to the center of gravity O of the flexible film 412A in plan view. In such a configuration, the flexible membrane can be vibrated with the center of gravity O of the flexible membrane 412A as the center of vibration (that is, the maximum displacement point). Thereby, the flexible film 412A can be vibrated efficiently, and the transmission output of the transmission transducer 45 can be improved.

The first piezoelectric element 451 is provided at a position overlapping the center of gravity O (maximum displacement point) of the flexible film 412A. Thereby, the flexible film can be vibrated efficiently by the first piezoelectric element 451. Therefore, the transmission output of the transmission transducer 45 can be improved.
The second piezoelectric element 455 is provided along the outer edge 412B of the flexible film 412A. In such a configuration, the second piezoelectric element 455 can be disposed at a position further away from the center of gravity O of the flexible film 412A. Therefore, it is possible to suppress the vibration of the flexible film 412A around the center of gravity O from being inhibited by the second piezoelectric element 455, and it is possible to suppress a decrease in the transmission output of the transmission transducer 45.

In the present embodiment, the first piezoelectric element 451 is provided on the surface on the + Z side of the flexible film 412A, and the second piezoelectric element 455 is provided on the surface on the −Z side of the flexible film 412A. In such a configuration, when a voltage is applied to each piezoelectric element 451, 455, there is a difference in shrinkage between the surface on the flexible film 412A side and the surface on the opposite side of each piezoelectric film 453, 457, Stresses in opposite directions act on the flexible film 412A from the piezoelectric elements 451 and 455. As a result, the vibration period of the flexible membrane 412A can be increased as described above, and the natural frequency can be increased while suppressing a decrease in the transmission output of the transmission transducer 45.
In addition, since the second piezoelectric element 455 is provided on the surface of the flexible film 412A opposite to the surface on which the first piezoelectric element 451 is provided, each of the second piezoelectric elements 455 is different from the configuration provided on the same surface. It is easy to form the piezoelectric elements 451 and 455.

[Second Embodiment]
Next, a second embodiment will be described.
In the first embodiment, the transmission array TA includes a plurality of transmission transducers 45 having the same natural frequency. On the other hand, the second embodiment is different in that the transmission array includes transmission transducers having different natural frequencies.
Hereinafter, the receiving transducer according to the present embodiment will be described. In the following description, components similar to those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

FIG. 13 is a plan view of the element substrate 41 of the transmission unit TU as viewed from the sealing plate 42 side.
As illustrated in FIG. 13, the transmission unit TU of the present embodiment includes a plurality of first transmission transducers 45 and a plurality of second transmission transducers 46.
The first transmission transducer 45 corresponds to a first ultrasonic transducer and is configured in the same manner as the transmission transducer 45 of the first embodiment. A plurality of the first transmission transducers 45 are arranged along the Y direction to constitute a first transmission transducer group 45A which is one transmission channel.
The second transmission transducer 46 corresponds to a second ultrasonic transducer and is different from the first transmission transducer 45 except for having a natural frequency (transmission frequency) different from that of the first transmission transducer 45. The configuration is substantially the same. A plurality of the second transmission transducers 46 are arranged along the Y direction to constitute a second transmission transducer group 46A which is one transmission channel.

  The first transmission transducer group 45A and the second transmission transducer group 46A are alternately arranged in the X direction to form a transmission array TA having a one-dimensional array structure. That is, in the transmission array TA, transmission channels having different transmission frequencies are arranged along the X direction and can transmit ultrasonic waves having different frequencies.

  Here, the second transmission transducer 46 includes a flexible film 412A, a first piezoelectric element 451 (see FIG. 4), and a second piezoelectric element 461. The second piezoelectric element 461 includes a second lower electrode 462, a second piezoelectric film 463, and a second upper electrode 464, and in a plan view, like the second piezoelectric element 455 of the first embodiment. Along the outer edge 412B of the flexible film 412A, the center of gravity O is surrounded and formed in a point-symmetrical annular shape with respect to the center of gravity O.

  The width w2 (width in the X direction (direction parallel to the short side)) of the second piezoelectric element 461 is different from the width w1 of the second piezoelectric element 455 of the first transmitting transducer 45. That is, the second piezoelectric element 461 has an area different from that of the second piezoelectric element 455 of the first transmission transducer 45 in plan view. For this reason, the second piezoelectric element 455 of the first transmission transducer 45 and the second piezoelectric element 461 of the second transmission transducer 46 have different magnitudes of stress applied to the flexible film 412A during driving. Accordingly, the second transmission transducer 46 has a natural frequency different from that of the first transmission transducer 45 and can transmit ultrasonic waves having different frequencies.

  For example, by setting the width of each of the second piezoelectric elements 455 and 461 within the range of 0.2 W or less as described above, according to the width of each of the second piezoelectric elements 455 and 461, each transmission transducer 45, 46 natural frequencies can be set. In the case of this embodiment, the natural frequency of the second transmission transducer 46 can be made larger than the natural frequency of the first transmission transducer 45.

In the plurality of second piezoelectric elements 461 constituting the second transmitting transducer group 46A, the second lower electrode 462 is formed in the terminal region Ar2 by the first lower electrode line 462A and the second lower lead line 462B. Two lower electrode pads 462P are connected. The second lower electrode pad 462P is connected to the circuit board 23.
The second upper electrode 464 is connected to the first transmitting transducer group 45A adjacent in the X direction by the second upper electrode line 464A. The second transmitting transducer group 46A arranged at both ends in the X direction is connected to the upper electrode pad 458P formed in the terminal region Ar2 by the upper lead line 458B.

  Although illustration is omitted, in this embodiment, the reception unit RU includes a reception transducer 55 having a natural frequency corresponding to the transmission frequency of each of the first transmission transducer 45 and the second transmission transducer 46. I have. Thereby, the ultrasonic wave transmitted from the transmission unit TU and reflected in the living body can be received by the reception unit RU.

[Operational effects of the second embodiment]
The transmission array TA includes a first transmission transducer 45 and a second transmission transducer 46, and the second piezoelectric element 455 of the first transmission transducer 45 and the second transmission transducer 46. The second piezoelectric element 461 has a different width in the X direction (short side direction) and a different area. That is, the magnitude of the stress applied from the second piezoelectric elements 455 and 461 to the flexible film 412A and the area to which the stress is applied are different. For this reason, the first transmission transducer 45 and the second transmission transducer 46 can transmit ultrasonic waves having different frequencies. That is, the transmission array TA can transmit ultrasonic waves having different frequencies. For example, the frequency of the ultrasonic waves can be appropriately selected according to required resolution, output, and the like.
Further, by setting the width of each of the second piezoelectric elements 455 and 461 within the range of 0.2 W or less as described above, according to the width of each of the second piezoelectric elements 455 and 461, each transmission transducer 45, 46 natural frequencies can be set. It is easy to set the natural frequency of each of the transmission transducers 45 and 46.

[Third embodiment]
Next, a third embodiment will be described.
In the first embodiment, each electrode pad 452P, 454P, 456P, 458P of the transmission unit TU is individually connected to the selection circuit 231. The transmission circuit 232 outputs a drive signal so that the first piezoelectric element 451 and the second piezoelectric element 455 of one transmission transducer group 45A are driven in synchronization. In contrast, in the third embodiment, the first lower electrode pad 452P and the second lower electrode pad 456P of the transmitting transducer group 45A are connected to the selection circuit 231 after being connected in advance. Is different.

FIG. 14 is a cross-sectional view showing a schematic configuration of a transmission unit TU according to the third embodiment.
As shown in FIG. 14, the first lower electrode pad 452P and the second lower electrode pad 456P are connected by a first through electrode 416 that penetrates the vibration film 412 along the Z direction.
Further, a second through electrode 423 that penetrates the sealing plate 42 along the Z direction is formed at a position overlapping the second lower electrode pad 456P on the sealing plate 42.
The second lower electrode pad 456 </ b> P and the electrode pad 424 formed on the −Z side surface of the sealing plate 42 are connected by the second through electrode 423. The first lower electrode pad 452P and the second lower electrode pad 456P are connected to the circuit board 23 through the electrode pad 424.
Although not shown in FIG. 14, the first upper electrode pad 454P and the second upper electrode pad 458P are similarly connected via the first through electrode 416, the second through electrode 423, and the electrode pad 424. The circuit board 23 is connected.
In such a configuration, when a drive signal from the transmission circuit 232 is output to the transmission transducer group 45A, the first lower electrode 452 and the first upper electrode 454, and the second lower electrode 456 and An electric field in the opposite direction is simultaneously applied between the second upper electrodes 458.

[Operational effects of the third embodiment]
In the present embodiment, the lower electrodes 452, 456 and the upper electrodes 454, 458 of the first piezoelectric element 451 and the second piezoelectric element 455 are short-circuited, respectively. In such a configuration, when the transmission transducer 45 is driven, the first piezoelectric element 451 and the second piezoelectric element 455 can be driven with the same drive signal. Therefore, it is easier to synchronize the drive timings of the piezoelectric elements 451 and 455 as compared to the configuration in which the piezoelectric elements 451 and 455 are individually driven. In addition, the configuration of each drive circuit such as the selection circuit 231 and the transmission circuit 232 can be simplified as compared with the case where the piezoelectric elements 451 and 455 are individually driven. In addition, the processing load on the control device 10 that controls the transmission transducer 45 and the drive circuit can be reduced.
In such a configuration, the number of electrode pads in the transmission unit TU can be reduced. For this reason, the wiring connection between the transmission unit TU and the circuit board 23 can be made easier.
[Modification of Third Embodiment]
FIG. 15 is a diagram illustrating a schematic configuration of an ultrasonic measurement apparatus according to a modification of the third embodiment.
In the third embodiment, as illustrated in FIG. 14, the configuration in which the corresponding electrode is short-circuited in the transmission unit TU is exemplified, but the configuration may be short-circuited in the circuit board 23.
As shown in FIG. 15, in the ultrasonic measurement apparatus 1, the first lower electrode pad 452P and the second lower electrode pad 456P of the transmitting transducer group 45A are connected and short-circuited on the circuit board 23 and then selected. The circuit 231 is connected. The first upper electrode pad 454P and the second upper electrode pad 458P are also connected and short-circuited on the circuit board 23, and then connected to the selection circuit 231 and set to a common potential.

Similarly, in the above modification, the configuration of each drive circuit such as the selection circuit 231 and the transmission circuit 232 can be simplified. In addition, the processing load on the control device 10 that controls the transmission transducer 45 and the drive circuit can be reduced. Further, since the corresponding electrode pads are short-circuited on the circuit board 23, the configuration of the transmission unit TU can be simplified.
In the third embodiment and the modification, if the first piezoelectric element 451 and the second piezoelectric element 455 can be driven in opposite directions, the first lower electrode 452 and the second upper electrode 458 are short-circuited, The second lower electrode 456 and the first upper electrode 454 may be short-circuited.

[Other variations]
Note that the present invention is not limited to the above-described embodiments, and the present invention includes configurations obtained by modifying, improving, and appropriately combining the embodiments as long as the object of the present invention can be achieved. Is.

  In each of the above embodiments, the drive voltage applied to the second piezoelectric element of each transmission transducer may be configured to be changeable. Thereby, the drive amount of a 2nd piezoelectric element can be changed and by extension, the natural frequency of a transmission transducer can be changed. Specifically, data indicating the relationship between the drive voltage and the natural frequency is stored in the storage unit 13, and the control unit 14 sets the drive voltage corresponding to the set natural frequency based on the data to the second value. A command signal to be applied to the piezoelectric element is output to the transmission circuit 232. The transmission circuit 232 applies a drive voltage based on the command signal to the second piezoelectric element.

  In each of the above embodiments, the first piezoelectric element has been illustrated as having a rectangular planar shape. However, the present invention is not limited to this. For example, the first piezoelectric element may be other polygonal shapes such as a circular shape, a triangular shape, and a pentagonal shape. Good. Similarly, the second piezoelectric element may be formed in an annular shape having various shapes.

In each of the above-described embodiments, the first piezoelectric element and the second piezoelectric element are illustrated as being point-symmetric with respect to the center of gravity O of the flexible film 412A. However, the present invention is not limited to this. For example, by providing the second piezoelectric element at a position away from the maximum displacement point of the flexible film 412A when only the first piezoelectric element is driven, the natural frequency of the transmitting transducer can be increased.
Further, the second piezoelectric element is not limited to the configuration in which the second piezoelectric element is disposed so as to surround the center of gravity O, and may be disposed at a position away from the maximum displacement point as described above.

  In each of the above embodiments, the center of gravity O of the flexible film 412A coincides with the maximum displacement point, and the first piezoelectric element is disposed at a position overlapping the center of gravity O, and the second piezoelectric element is disposed at a position away from the center of gravity O. Although illustrated, it is not limited to this. For example, the present invention also includes a case where the center of gravity O and the maximum displacement point are different, such as when the rigidity of the flexible film 412A changes along the surface direction. In this case, the first piezoelectric element may be disposed at a position overlapping the maximum displacement point, and the second piezoelectric element may be disposed at a position away from the maximum displacement point.

In each of the above embodiments, the first piezoelectric element is provided on the side opposite to the sealing plate 42 of the element substrate 41, and the second piezoelectric element is provided on the sealing plate 42 side of the element substrate 41. It is not limited.
FIG. 16 is a cross-sectional view schematically showing a modification of the transmission unit TU. In the modification shown in FIG. 16, the first piezoelectric element 451 is disposed on the sealing plate 42 side of the element substrate 41, and the second piezoelectric element 455 is disposed on the opposite side of the sealing plate 42. In such a configuration, the first piezoelectric element 451 starts to vibrate toward the flexible film 412A when, for example, a rectangular wave voltage having a predetermined frequency is applied to the first piezoelectric element 451 during transmission of the ultrasonic wave. . For this reason, the deformation speed when the flexible film 412A is deformed toward the + Z side can be increased, and the sound pressure can be improved. As shown in FIG. 5, when the first piezoelectric element 451 is provided on the + Z side of the flexible film 412A and the acoustic matching layer 43 is formed on the first piezoelectric element 451, as shown in FIG. Compared to the case where the acoustic matching layer 43 is formed on the second piezoelectric element 455, it is easier to fill the acoustic matching layer 43 without a gap. In other words, since the first piezoelectric element 451 has a simpler structure than the second piezoelectric element 455, the acoustic matching layer 43 is formed on the first piezoelectric element 451 more clearly than on the second piezoelectric element 455. Is easy.

Further, in each of the above embodiments, the suppressing portion 422 is formed on the sealing plate 42, but the present invention is not limited to this, and the suppressing portion may be formed on the −Z side surface of the element substrate 41. In addition, a suppression portion may be formed on the surface of the element substrate 41 on the + Z side.
FIG. 17 is a cross-sectional view schematically showing a modification of the transmission unit TU. In the modification shown in FIG. 17, a suppressing portion 417 is formed on the + Z side of the element substrate 41. The suppressing portion 417 is formed of, for example, the same material as that of the sealing plate 42, has a through-hole 417 A formed at a position corresponding to the flexible film 412 A, and is bonded and fixed to the element substrate 41. The suppressing portion 417 can improve the strength of the element substrate 41 and can suppress the warpage of the element substrate 41. Moreover, since the suppression part 417 is provided in the side in which the 1st piezoelectric element 451 which has a simpler structure than the 2nd piezoelectric element 455 is provided, compared with the case where the 2nd piezoelectric element 455 is provided in the + Z side. The positioning of the suppressing portion 417 is easy. Further, as described above, the acoustic matching layer 43 can be easily filled.
In addition, as shown in FIG. 5, when the suppression part 422 is formed in the sealing plate 42, it is not necessary to provide the above-mentioned suppression part 417 in the element substrate 41, and the number of parts can be reduced, and the manufacturing process is simplified. it can.

FIG. 18 is a cross-sectional view schematically showing a modification of the transmission unit TU. In the modification shown in FIG. 18, a suppressing portion 417 is formed on the + Z side of the element substrate 41. The first piezoelectric element 451 is disposed on the sealing substrate 42 side of the element substrate 41, and the second piezoelectric element 455 is disposed on the opposite side of the sealing plate 42. Even in such a configuration, the strength of the element substrate 41 can be improved by the suppressing portion 417, and the occurrence of warping of the element substrate 41 can be suppressed. In the modification shown in FIGS. In addition, the concave groove 421 may be formed, which can suppress the occurrence of crosstalk as described above.

  In each said embodiment, although the 1st piezoelectric element and the 2nd piezoelectric element were arrange | positioned so that 412A of flexible films may be pinched | interposed, it is not limited to this, You may form in the same surface. In this case, what is necessary is just to comprise so that the phase of a vibration of a 1st piezoelectric element and a 2nd piezoelectric element may become an antiphase. Thereby, the natural frequency of the transmitting transducer can be increased as in the above embodiments.

  In each said embodiment, although the structure provided with a piezoelectric element as a 1st vibration part and 2nd vibration part which vibrate flexible film 412A was illustrated, it is not limited to this. For example, the first vibration unit and the second vibration unit may include a vibrator such as an electrostatic actuator. Even in such a case, the natural frequency can be increased while suppressing a decrease in the transmission output of the transmission transducer by adopting a configuration in which the first vibrating portion and the second vibrating portion are vibrated in opposite directions.

  In each of the above embodiments, the transmission array TA and the reception array RA have substantially the same area. However, the present invention is not limited to this, and may have different surfaces. Further, the arrangement positions of the transmission array TA and the reception array RA are not limited to the example in FIG. 3. For example, a configuration in which the reception array RA is provided in a part of the transmission array TA or a transducer group for transmission (transmission) The channel) and the receiving transducer group (receiving channel) may be arranged alternately along the X direction (scanning direction), for example. Further, the transmission unit TU and the reception unit RU are not limited to a configuration in which the transmission unit TU and the reception unit RU are integrally stored in the casing 21. A transmission probe including only the transmission unit TU and a reception probe including only the reception unit RU are provided. The structure provided may be sufficient, and only the probe for transmission may be provided.

  In each of the above embodiments, the configuration using an ultrasonic device having a one-dimensional array structure has been exemplified. However, the present invention is not limited to this, and has a two-dimensional array structure configured to be able to individually drive each transducer. An ultrasonic device may be used. In this case, an acoustic lens is unnecessary.

  In each said embodiment, although the ultrasonic measuring device which makes an organ in a living body a measuring object was illustrated, it is not limited to this. For example, the present invention can be applied to a measuring machine that uses various structures as a measurement object and detects defects in the structures or inspects aging. Further, for example, the present invention can be applied to a measuring machine that detects a defect of the measurement target using a semiconductor package, a wafer, or the like as the measurement target.

  In addition, the specific structure for carrying out the present invention may be configured by appropriately combining the above-described embodiments and modifications within the scope that can achieve the object of the present invention, and may be appropriately changed to other structures and the like. May be.

  DESCRIPTION OF SYMBOLS 1 ... Ultrasonic measuring apparatus, 2 ... Ultrasonic probe, 10 ... Control apparatus, 14 ... Control part, 21 ... Housing | casing, 22 ... Ultrasonic device, 23 ... Circuit board, 24 ... Ultrasonic sensor, 41 ... Element board | substrate, 42 ... sealing plate, 43 ... acoustic matching layer, 44 ... acoustic lens, 45 ... first transmission transducer, 46 ... second transmission transducer, 412 ... vibration membrane, 412A ... flexible membrane, 412B ... outer edge, 413 ... first layer, 414 ... second layer, 415 ... third layer, 421 ... concave groove, 422 ... inhibiting portion, 451 ... first piezoelectric element, 452 ... first lower electrode, 452A ... first lower electrode Wires 453 ... first piezoelectric film, 454 ... first upper electrode, 455 ... second piezoelectric element, 456 ... second lower electrode, 456A ... second lower electrode wire, 457 ... second piezoelectric film, 458 ... second upper part Electrode, 461 ... second piezoelectric element, 462 ... second Department electrode, 463 ... second piezoelectric film, 464 ... second upper electrode, O ... center of gravity, RU ... receiving unit, TA ... transmit array, TU ... transmission unit.

Claims (11)

A flexible membrane;
A first vibrating portion and a second vibrating portion for vibrating the flexible membrane,
The ultrasonic transducer according to claim 2, wherein the second vibrating section is provided at a position away from a maximum displacement point of the flexible film in a plan view as viewed from the thickness direction of the flexible film. The ultrasonic transducer according to claim 1.
The ultrasonic transducer according to claim 1, wherein the first vibrating portion is provided at a position overlapping the maximum displacement point in the plan view. The ultrasonic transducer according to claim 1 or 2,
The first vibration part is provided at a position that is point-symmetric with respect to the maximum displacement point in the plan view.
The ultrasonic transducer according to claim 2, wherein the second vibrating section is provided at a position that is point-symmetric with respect to the maximum displacement point in the plan view. The ultrasonic transducer according to any one of claims 1 to 3,
The ultrasonic transducer according to claim 2, wherein the second vibrating portion is provided along an outer edge of the flexible film in the plan view. The ultrasonic transducer according to any one of claims 1 to 4,
The first vibration unit is a first piezoelectric element provided on one surface of the flexible film,
The ultrasonic transducer, wherein the second vibrating section is a second piezoelectric element provided on the other surface of the flexible film. The ultrasonic transducer according to claim 5.
The first piezoelectric element has a configuration in which a first electrode, a first piezoelectric body, and a second electrode are stacked from the flexible film side,
The second piezoelectric element has a configuration in which a third electrode, a second piezoelectric body, and a fourth electrode are laminated from the flexible film side,
One of the first electrode and the second electrode and one of the third electrode and the fourth electrode are short-circuited,
The other of said 1st electrode and said 2nd electrode, and the other of said 3rd electrode and said 4th electrode are short-circuited. The ultrasonic transducer characterized by the above-mentioned. An ultrasonic array comprising a plurality of ultrasonic transducers comprising a flexible membrane, and a first vibrating portion and a second vibrating portion that vibrate the flexible membrane,
The ultrasonic array, wherein the second vibrating portion is provided at a position away from a maximum displacement point of the flexible film in a plan view as viewed from the thickness direction of the flexible film. The ultrasound array of claim 7,
The first ultrasonic transducer of the plurality of ultrasonic transducers and the second ultrasonic transducer have different areas of the region where the second vibration unit is arranged in the plan view. Features ultrasonic array. A flexible membrane;
A first vibrating portion and a second vibrating portion that vibrate the flexible membrane;
A circuit board to which the first vibrating part and the second vibrating part are connected,
The ultrasonic module, wherein the second vibrating section is provided at a position away from a maximum displacement point of the flexible film in a plan view as viewed from the thickness direction of the flexible film. A transmission unit including an ultrasonic transducer including a flexible film, and a first vibration unit and a second vibration unit configured to vibrate the flexible film, and transmitting an ultrasonic wave from the ultrasonic transducer;
A receiving unit for receiving ultrasonic waves,
The ultrasonic measurement apparatus, wherein the second vibration unit is provided at a position away from a maximum displacement point of the flexible film in a plan view as viewed from the thickness direction of the flexible film. An ultrasonic transducer comprising: a flexible membrane; and a first vibrating portion and a second vibrating portion that vibrate the flexible membrane;
A control unit for controlling the ultrasonic transducer,
Said 2nd vibration part is provided in the position distant from the maximum displacement point of the said flexible film in the planar view seen from the thickness direction of the said flexible film. The electronic device characterized by the above-mentioned.

Images