JP2018068620A - Ultrasound device, ultrasound probe, and ultrasound apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasound device, an ultrasound probe, and an ultrasound apparatus, which can suppress the deterioration of the resolution due to trailing.SOLUTION: An ultrasound device 22 comprises: an ultrasound transducer array including a first region where a first ultrasound transducer 451 is mounted and a second region where a second ultrasound transducer 452 is mounted; a first acoustic layer 431 overlaid on the first region; a second acoustic layer 432 overlaid on the second region; and an acoustic lens 44 mounted across the first acoustic layer and the second acoustic layer and having an acoustic impedance greater than that of the first acoustic layer and the second acoustic layer. A first dimension L1 of the first acoustic layer in the layering direction is integer n times λa/2, where λa is the wavelength of an ultrasound wave transmitted in the first acoustic layer by the first ultrasound transducer. A second dimension L2 of the second acoustic layer in the layering direction is integer n times λb/2, where λb is the wavelength of an ultrasound wave received in the second acoustic layer by the second ultrasound transducer.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an ultrasonic device, an ultrasonic probe, and an ultrasonic apparatus.

  Conventionally, an ultrasonic array in which a plurality of ultrasonic transducer elements (ultrasonic transducers) for transmitting and receiving ultrasonic waves are arranged in an array, a protective layer (acoustic layer) provided on the ultrasonic array, An ultrasonic transducer element unit (ultrasonic device) including an acoustic lens provided on an acoustic layer is known (for example, Patent Document 1).

  In the ultrasonic device described in Patent Document 1, the ultrasonic transducer includes a vibration film and a piezoelectric element as a vibrator provided on the vibration film. The ultrasonic device is configured by sequentially stacking an acoustic layer and an acoustic lens on a vibration film. This ultrasonic device transmits and receives ultrasonic waves in a state where the acoustic lens is in contact with a measurement object such as a living body. For example, an ultrasonic wave transmitted by driving a piezoelectric element propagates through an acoustic layer and an acoustic lens, and then is output from the surface of the acoustic lens to the living body.

JP 2014-198197 A

  Here, in the conventional ultrasonic device as described in Patent Document 1, the acoustic impedance of the acoustic layer is made larger than that of the acoustic lens, and the thickness of the acoustic layer is set to half the wavelength of the ultrasonic wave in the acoustic layer. By doing so, the influence of the reverberation of ultrasonic waves can be suppressed. That is, among the ultrasonic waves, a reverberation component after the second wave following the first wave having a large amplitude, that is, a so-called tailing portion, an interface between the ultrasonic transducer and the acoustic layer (first interface), an acoustic layer, It can be canceled by the reflected wave (interface reflected wave) generated at the interface (second interface) with the acoustic lens.

  For example, an interface reflected wave generated at the second interface among transmission waves from the ultrasonic transducer is reflected at the first interface and reenters the second interface. At this time, due to the phase inversion at the first interface, the interface reflected wave overlaps with the second wave of the transmission wave in the opposite phase, and the second wave and thereafter are canceled. Also, for example, the received wave directed to the ultrasonic transducer is reflected at the first interface, then reflected at the second interface, and is incident on the first interface again. Similarly, due to the phase inversion at the first interface, the interface reflected wave overlaps with the second wave of the received wave in the opposite phase, and the second wave and thereafter of the received wave cancel each other.

  However, in an ultrasonic array capable of receiving ultrasonic waves having a frequency different from that of the transmission wave, for example, higher-order harmonics of the transmission wave, when an acoustic layer having the same thickness is provided in the transmission region and the reception region, the transmission side is more There is a possibility that the influence of tailing becomes large on the receiving side. For example, when receiving the second harmonic, the wavelength of the received wave at the acoustic layer is half the value of the transmitted wave. For this reason, as for the thickness of the acoustic layer, the half wavelength of the transmission wave corresponds to one wavelength of the reception wave. Therefore, the interface reflection of the received wave generated at the first interface overlaps with the third wave of the received wave in the opposite phase when reflected by the second interface and reenters the first interface, and the second wave is not canceled out. . For this reason, the influence of tailing becomes larger than that on the transmission side, and the resolution may be lowered.

  An object of the present invention is to provide an ultrasonic device, an ultrasonic probe, and an ultrasonic apparatus that can suppress a decrease in resolution due to tailing.

  An ultrasonic device according to an application example of the present invention includes a first region in which a first ultrasonic transducer having a first vibrating membrane is provided, and a second region in which a second ultrasonic transducer having a second vibrating membrane is provided. An ultrasonic transducer array having a region, a first acoustic layer stacked on the first region of the ultrasonic transducer array, and a second stacked on the second region of the ultrasonic transducer array. An ultrasonic layer comprising: an acoustic layer; and an acoustic lens provided across the first acoustic layer and the second acoustic layer and having an acoustic impedance larger than that of the first acoustic layer and the second acoustic layer. In the stacking direction of the first acoustic layer relative to the array, the first dimension of the first acoustic layer is the first of the ultrasonic waves transmitted by the first ultrasonic transducer. The wavelength in the acoustic layer is λa, which is an integer n times λa / 2. In the stacking direction, the second dimension of the second acoustic layer is the second ultrasonic wave received by the second ultrasonic transducer. The wavelength in the acoustic layer is λb, which is n times λb / 2.

In this application example, the first dimension of the first acoustic layer stacked in the first region of the ultrasonic transducer array is an integer n times λa / 2. The second dimension of the second acoustic layer is an integer n times λb / 2. Thereby, when receiving the ultrasonic wave of a frequency different from the ultrasonic wave transmitted from the first ultrasonic transducer by the second ultrasonic transducer, for example, the transmission wave (fundamental wave) from the first ultrasonic transducer. Even when high-order harmonics are received, a reduction in resolution can be suppressed.
Here, the phase of the ultrasonic wave propagating through the first acoustic layer is inverted when reflected at the interface with the first ultrasonic transducer. Similarly, the phase of the ultrasonic wave propagating through the second acoustic layer is inverted when reflected at the interface with the second ultrasonic transducer.
In this application example, a reflected wave (first wave) generated at the interface (second interface) between the first acoustic layer and the acoustic lens in the ultrasonic wave (transmitted wave and fundamental wave) transmitted from the first ultrasonic transducer. 1 reflected wave) is reflected at the interface (first interface) between the first acoustic layer and the first ultrasonic transducer, and then enters the first interface again. At this time, since the first dimension is (λa / 2) · n, the propagation distance of the first reflected wave is λa · n corresponding to reciprocation of the first acoustic layer. For this reason, at the second interface, the phase of the first reflected wave is delayed by 2nπ with respect to the transmission wave and has an opposite phase. Therefore, the first reflected wave cancels out the (n + 1) th wave in the reverberation part of the transmission wave.
On the other hand, among the reflected waves from the measurement object, the reflected wave (second reflected wave) reflected at the interface (first interface) between the second acoustic layer and the second ultrasonic transducer is the second acoustic layer and the acoustic wave. After being reflected at the interface (third interface) with the lens, it is incident on the second interface again. At this time, since the second dimension is (λb / 2) · n, similarly, the phase of the second reflected wave is delayed by 2nπ with respect to the received wave and has an opposite phase. Therefore, the second and following reflected waves cancel out the (n + 1) th and subsequent waves in the reverberation portion of the received wave.
From the above, since both the transmitting side and the receiving side can cancel at least the (n + 1) -th wave and after among the reverberation components of the ultrasonic wave, it is possible to suppress a decrease in resolution due to the influence of tailing and to suppress a decrease in measurement accuracy. .

In the ultrasonic device according to this application example, it is preferable that the first dimension is λa / 2 and the second dimension is λb / 2.
This application example corresponds to n = 1 in the above application example. That is, according to this application example, at least both the second and subsequent waves of the reverberation component of the ultrasonic wave can be canceled on both the transmission side and the reception side, the influence of tailing can be suitably suppressed, and the measurement accuracy is reduced. Can be suppressed more reliably.

  An ultrasonic device according to an application example of the present invention includes a first region in which a first ultrasonic transducer having a first vibrating membrane is provided, and a second region in which a second ultrasonic transducer having a second vibrating membrane is provided. An ultrasonic transducer array having a region, a first acoustic layer stacked on the first region of the ultrasonic transducer array, and a second stacked on the second region of the ultrasonic transducer array. An acoustic lens, and an acoustic lens provided across the first acoustic layer and the second acoustic layer and having an acoustic impedance larger than that of the first acoustic layer and the second acoustic layer, and the second acoustic layer. Is located on the opposite side of the first layer on the ultrasonic transducer array side and the ultrasonic transducer array, and has an acoustic impedance smaller than that of the first layer. And in the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, the first dimension of the first acoustic layer is the ultrasonic wave transmitted by the first ultrasonic transducer. The wavelength is λa, which is an integer n times λa / 2, and the dimensions of the first layer and the second layer in the stacking direction are the second sound of the ultrasonic wave received by the second ultrasonic transducer. A wavelength in the layer is λb, which is an odd multiple of λb / 4, and a dimension of at least one of the first layer and the second layer is n times or less of λb / 2.

In this application example, the first dimension of the first acoustic layer stacked in the first region of the ultrasonic transducer array is an integer n times λa / 2. The second acoustic layer has a first layer and a second layer. The dimensions of the first layer and the second layer are odd multiples of λb / 4, and at least one of the dimensions of the first layer and the second layer is n times or less of λb / 2. Thus, as in the above application example, when receiving an ultrasonic wave having a frequency different from the ultrasonic wave transmitted from the first ultrasonic transducer by the second ultrasonic transducer, for example, the first ultrasonic transducer Therefore, even when a high-order harmonic with respect to the transmission wave (fundamental wave) is received, a decrease in resolution can be suppressed.
Here, the phase of the ultrasonic wave propagating through the first acoustic layer is inverted when reflected at the interface with the first ultrasonic transducer. Similarly, the phase of the ultrasonic wave propagating through the first layer of the second acoustic layer is reversed when reflected at the interface with the second ultrasonic transducer or the interface with the second layer.
In this application example, as in the above application example, the phases of the transmission wave and the first reflected wave transmitted from the first ultrasonic transducer are opposite to each other, and the (n + 1) th and subsequent waves in the reverberation part of the transmission wave Offset.
On the other hand, among the received waves from the measurement target, the second reflected wave reflected at the interface (first interface) between the second acoustic layer and the second ultrasonic transducer is the third interface or the first layer and the first layer. After being reflected at the interface (fourth interface) with the two layers, when it enters the first interface again, it has an opposite phase to the received wave. Of the received waves, the reflected wave reflected at the fourth interface (third reflected wave) is reflected at the third interface and then enters the fourth interface again to be in reverse phase with the received wave. Offset.
Furthermore, the dimension of at least one of the first layer and the second layer is not more than n times λb / 2. For this reason, as in the above application example, at least one of the second reflected wave and the third reflected wave has a delay amount of 2nπ or less and an opposite phase with respect to the received wave. For this reason, at least the (n + 1) th wave and thereafter in the reverberation part of the received wave is canceled.
From the above, on both the transmission side and the reception side, it is possible to suppress a decrease in resolution due to the detection of at least the (n + 1) th wave of the reverberation component of the ultrasonic wave, that is, a decrease in measurement accuracy due to the influence of tailing. Can be suppressed.

In the ultrasonic device according to this application example, it is preferable that the first acoustic layer and the second acoustic layer have the same dimensions.
In this application example, the dimension of the first acoustic layer and the dimension of the second acoustic layer are the same. Thereby, the interface with each acoustic layer of the acoustic lens provided over the first acoustic layer and the second acoustic layer can be flat, and the configuration of the acoustic lens can be simplified.

In the ultrasonic device according to this application example, it is preferable that the first dimension is λa / 2, and one dimension of the first layer and the second layer is λb / 4.
In this application example, as in the above application example, the second and subsequent waves of the reverberation component of the transmission wave can be canceled. On the receiving side, the dimension of one of the first layer and the second layer is λb / 4 smaller than λb / 2 corresponding to n = 1. Thereby, in the said one layer, at least the 2nd wave and after among the reverberation components of a received wave can be canceled. Therefore, the influence of tailing can be suitably suppressed, and a decrease in measurement accuracy can be suppressed.

An ultrasonic probe according to an application example of the present invention includes a first region in which a first ultrasonic transducer having a first vibration film is provided, and a second ultrasonic transducer having a second vibration film. An ultrasonic transducer array having a second region; a first acoustic layer stacked on the first region of the ultrasonic transducer array; and a second region stacked on the second region of the ultrasonic transducer array. A second acoustic layer, an acoustic lens provided across the first acoustic layer and the second acoustic layer, and having a larger acoustic impedance than the first acoustic layer and the second acoustic layer, and the ultrasonic transducer array A housing for housing the first acoustic layer, the second acoustic layer, and the acoustic lens, and the first acoustic layer with respect to the ultrasonic transducer array. In the layer direction, the first dimension of the first acoustic layer is an integer n times λa / 2, where λa is a wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer in the first acoustic layer, In the stacking direction, the second dimension of the second acoustic layer is λb, where n is the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer, and is n times λb / 2. And
In the ultrasonic probe of this application example configured as described above, as in the above application example, both the transmitted wave and the received wave cancel out the n + 1-th wave and after in the reverberation part. Therefore, the reverberation component of the ultrasonic wave is detected, that is, a decrease in resolution due to the influence of tailing can be suppressed, and a decrease in measurement accuracy can be suppressed.

An ultrasonic probe according to an application example of the present invention includes a first region in which a first ultrasonic transducer having a first vibration film is provided, and a second ultrasonic transducer having a second vibration film. An ultrasonic transducer array having a second region; a first acoustic layer stacked on the first region of the ultrasonic transducer array; and a second region stacked on the second region of the ultrasonic transducer array. A second acoustic layer, an acoustic lens provided across the first acoustic layer and the second acoustic layer, and having a larger acoustic impedance than the first acoustic layer and the second acoustic layer, and the ultrasonic transducer array A housing for housing the first acoustic layer, the second acoustic layer, and the acoustic lens, wherein the second acoustic layer is provided on the ultrasonic transducer array side. A layer, and a second layer located on the opposite side of the ultrasonic transducer array and having an acoustic impedance smaller than that of the first layer, the first acoustic layer being stacked on the ultrasonic transducer array In the direction, the first dimension of the first acoustic layer is an integer n times λa / 2, where λa is the wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer. The dimensions of the layer and the second layer are an odd multiple of λb / 4, where λb is the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer, and the first layer and the second layer The dimension of at least one of the two layers is not more than n times λb / 2.
In the ultrasonic probe of this application example configured as described above, the n + 1th wave and subsequent waves in the reverberation part of the transmission wave are canceled out as in the above application example. In addition, at least one of the first layer and the second layer cancels out at least the (n + 1) th wave in the reverberation portion of the received wave. Therefore, on both the transmission side and the reception side, a reverberation component of ultrasonic waves can be detected, that is, a decrease in resolution due to the influence of tailing can be suppressed, and a decrease in measurement accuracy can be suppressed.

An ultrasonic apparatus according to an application example of the present invention includes a first region in which a first ultrasonic transducer having a first vibration film is provided, and a second area in which a second ultrasonic transducer having a second vibration film is provided. An ultrasonic transducer array having a region, a first acoustic layer stacked on the first region of the ultrasonic transducer array, and a second stacked on the second region of the ultrasonic transducer array. An acoustic layer, an acoustic lens provided across the first acoustic layer and the second acoustic layer, having an acoustic impedance larger than that of the first acoustic layer and the second acoustic layer, the first ultrasonic transducer, A control unit for controlling the second ultrasonic transducer, and in the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, The first dimension of the first acoustic layer is a wavelength in the first acoustic layer of the ultrasonic wave transmitted by the first ultrasonic transducer, and is an integer n times λa / 2. In the stacking direction, The second dimension of the second acoustic layer is characterized in that the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer is λb and n times λb / 2.
In the ultrasonic apparatus according to this application example configured as described above, similarly to the above application example, both the transmission wave and the reception wave cancel out the (n + 1) th wave in the reverberation part. Therefore, the reverberation component of the ultrasonic wave is detected, that is, a decrease in resolution due to the influence of tailing can be suppressed, and a decrease in measurement accuracy can be suppressed.

An ultrasonic apparatus according to an application example of the present invention includes a first region in which a first ultrasonic transducer having a first vibration film is provided, and a second area in which a second ultrasonic transducer having a second vibration film is provided. An ultrasonic transducer array having a region, a first acoustic layer stacked on the first region of the ultrasonic transducer array, and a second stacked on the second region of the ultrasonic transducer array. An acoustic layer, an acoustic lens provided across the first acoustic layer and the second acoustic layer, having an acoustic impedance larger than that of the first acoustic layer and the second acoustic layer, the first ultrasonic transducer, A control unit for controlling the second ultrasonic transducer, wherein the second acoustic layer includes a first layer on the ultrasonic transducer array side, and the ultrasonic wave A second layer located on the opposite side of the transducer array and having an acoustic impedance smaller than that of the first layer, and in the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, the first layer The first dimension of the acoustic layer is an integer n times λa / 2, where λa is the wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer, and the first layer and the second layer in the stacking direction Λb is an odd multiple of λb / 4, where λb is the wavelength of the ultrasonic waves received by the second ultrasonic transducer in the second acoustic layer, and at least one of the first layer and the second layer. One dimension is not more than n times λb / 2.
In the ultrasonic apparatus of this application example configured as described above, similarly to the application example described above, the (n + 1) th and subsequent waves in the reverberation portion of the transmission wave are canceled. In addition, at least one of the first layer and the second layer cancels out at least the (n + 1) th wave in the reverberation portion of the received wave. Therefore, on both the transmission side and the reception side, a reverberation component of ultrasonic waves can be detected, that is, a decrease in resolution due to the influence of tailing can be suppressed, and a decrease in measurement accuracy can be suppressed.

1 is a diagram showing a schematic configuration of an ultrasonic apparatus according to a first embodiment. FIG. 3 is a cross-sectional view illustrating a schematic configuration of the ultrasonic probe according to the first embodiment. The top view which looked at the element substrate of the ultrasonic device of a 1st embodiment from the sealing board side. Sectional drawing which shows the cross section of the ultrasonic device of 1st Embodiment typically. The figure explaining the effect | action of the ultrasonic device of 1st Embodiment. The figure explaining the effect | action of the ultrasonic device of 1st Embodiment. Sectional drawing which shows schematic structure of the ultrasonic device of 2nd Embodiment. The figure explaining the effect | action of the ultrasonic device of 2nd Embodiment. Sectional drawing which shows schematic structure of the ultrasonic device which concerns on a modification.

[First Embodiment]
Hereinafter, the ultrasonic measurement apparatus according to the first embodiment will be described with reference to the drawings.
FIG. 1 is a perspective view showing a schematic configuration of the ultrasonic measurement apparatus 1.
The ultrasonic measurement device 1 corresponds to an ultrasonic device, and includes an ultrasonic probe 2 and a control device 10 connected to the ultrasonic probe 2 via a cable 3 as shown in FIG.
The ultrasonic measurement apparatus 1 makes an ultrasonic probe 2 abut on the surface of a living body (for example, a human body) as a measurement target, and transmits ultrasonic waves from the ultrasonic probe 2 into the living body. In addition, the ultrasonic measurement apparatus 1 receives the second harmonic of the ultrasonic waves reflected by the organs in the living body with the ultrasonic probe 2, and based on the received signal, for example, an internal fault in the living body. An image is acquired or the state of an organ in a living body (for example, blood flow) is measured.

[Configuration of control device]
The control device 10 corresponds to a control unit, and includes an operation unit 11 including buttons and a touch panel, and a display unit 12 as illustrated in FIG. Although not shown, the control device 10 includes a storage unit configured by a memory or the like, and a calculation unit configured by a CPU (Central Processing Unit) or the like. The control device 10 controls the ultrasonic measurement device 1 by causing the calculation unit to execute various programs stored in the storage unit. For example, the control device 10 outputs a command for controlling the driving of the ultrasonic probe 2 or forms an image of the internal structure of the living body based on the reception signal input from the ultrasonic probe 2 to display the display unit. 12 or the biological information such as blood flow is measured and displayed on the display unit 12. As such a control apparatus 10, terminal devices, such as a tablet terminal, a smart phone, and a personal computer, can be used, for example, You may use the dedicated terminal device for operating the ultrasonic probe 2. FIG.

[Configuration of ultrasonic probe]
FIG. 2 is a cross-sectional view showing a schematic configuration of the ultrasonic probe 2.
The ultrasonic probe 2 corresponds to an ultrasonic probe, and as shown in FIG. 2, a housing 21, an ultrasonic device 22 housed in the housing 21, and an ultrasonic device 22 are controlled. And a circuit board 23 provided with a driver circuit and the like. The ultrasonic device 22 and the circuit board 23 constitute an ultrasonic sensor 24 corresponding to an ultrasonic module.

[Case configuration]
As shown in FIG. 1, the casing 21 is formed in, for example, 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 22 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 filled with, for example, a resin material, so that waterproofness is ensured.
In the present embodiment, the configuration in which the ultrasonic probe 2 and the control device 10 are connected using the cable 3 is illustrated, 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 circuit board]
The circuit board 23 is electrically connected to the first signal terminal 414P and the common terminal 416P (see FIG. 3) of the ultrasonic device 22, and controls the ultrasonic device 22 based on the control of the control device 10.
Specifically, the circuit board 23 includes a transmission circuit, a reception circuit, and the like. The transmission circuit outputs a drive signal that causes the ultrasonic device 22 to perform ultrasonic transmission. The reception circuit acquires the reception signal output from the ultrasonic device 22 that has received the ultrasonic wave, performs amplification processing, AD conversion processing, phasing addition processing, and the like on the reception signal and outputs the received signal to the control device 10. To do.

[Configuration of ultrasonic device]
FIG. 3 is a plan view of the element substrate 41 in the ultrasonic device 22 as viewed from the sealing plate 42 side. FIG. 4 is a cross-sectional view including a central portion of the ultrasonic device 22.
As shown in FIG. 4, the ultrasonic device 22 includes an element substrate 41 provided with an ultrasonic transducer array 46, a sealing plate 42, an acoustic layer 43 including a first acoustic layer 431 and a second acoustic layer 432. And an acoustic lens 44.

(Configuration of element substrate)
The element substrate 41 corresponds to a substrate and includes a substrate body 411 and a vibration film 412 provided on the sealing plate 42 side of the substrate body 411 as shown in FIG. Here, in the following description, the surface of the substrate body 411 on the acoustic lens 44 side is referred to as a front surface 411A, and the surface facing the sealing plate 42 is referred to as a back surface 411B. Further, a surface (corresponding to one surface) of the vibrating membrane 412 opposite to the sealing plate 42 is referred to as an opening surface 412A, and a surface on the sealing plate 42 side is referred to as an operation surface 412B.

As shown in FIG. 4, the substrate body 411 is a substrate that supports the vibration film 412, and is made of a semiconductor substrate such as Si, for example.
The vibration film 412 is made of, for example, SiO ₂ , a laminated body of SiO ₂ and ZrO ₂ , and is provided on the back surface 411B of the substrate body 411. The thickness dimension of the vibration film 412 is sufficiently small with respect to the substrate main body 411.

As shown in FIG. 3, an ultrasonic transducer array 46 configured to transmit and receive ultrasonic waves is provided in the array area Ar <b> 1 in the center of the element substrate 41. In FIG. 3, for convenience of explanation, the number of ultrasonic transducers 45 is reduced, but in reality, more ultrasonic transducers 45 are arranged.
The ultrasonic transducer array 46 receives a transmission array 461 having a first ultrasonic transducer 451 for transmitting ultrasonic waves of a predetermined frequency (hereinafter also referred to as a fundamental wave), and second harmonics with respect to the fundamental wave. And a receiving array 462 having a second ultrasonic transducer 452.

(Transmission array configuration)
The transmission array 461 is provided in the transmission area (first area) Ar11 in the array area Ar1. The transmission array 461 is configured by arranging a plurality of first ultrasonic transducers 451 that transmit a fundamental wave among the ultrasonic transducers 45 in an array. The transmission array 461 is composed of a plurality of first ultrasonic transducers 451 arranged along the X direction (slice direction), and has a plurality of transmission rows 451A that function as one transmission channel. The plurality of transmission strings 451A are arranged in the Y direction (scan direction).

  The first ultrasonic transducer 451 is a vibration region of a vibration film 412 described later, and includes a first flexible part 412C corresponding to the first vibration film and a first piezoelectric element 413 provided in the first flexible part 412C. And comprising. The first ultrasonic transducer 451 is configured to be able to transmit ultrasonic waves having a frequency (fundamental wave) corresponding to the dimensions of the first flexible portion 412C in the X direction and the Y direction.

  The substrate main body 411 is provided with first openings 411C corresponding to the first ultrasonic transducers 451. The first opening 411C is closed by the vibration film 412 on the back surface 411B side. That is, the vibrating membrane 412 has a first flexible portion 412C that closes the first opening 411C on the back surface 411B side. The first flexible portion 412C is a vibration region of the vibration film 412, and an outer edge is defined by the first opening 411C. As described above, the first ultrasonic transducer 451 can transmit a fundamental wave having a frequency corresponding to the outer dimension of the first flexible portion 412C. That is, the dimension of the first opening 411C in the X direction and the Y direction is set to a value corresponding to the frequency of the fundamental wave.

A first piezoelectric element 413 that is a laminate of a first lower electrode 414, a first piezoelectric film 415, and an upper electrode 416 is provided on the operating surface 412B of the first flexible portion 412C.
The first lower electrode 414 is formed linearly along the X direction across the plurality of first ultrasonic transducers 451 constituting the 1CH transmission line 451A. One end portion (−X side end portion) of the first lower electrode 414 is located in the terminal region Ar2 of the outer peripheral portion of the element substrate 41, and a first signal terminal 414P electrically connected to the circuit substrate 23 is provided. .

The upper electrode 416 is formed in a straight line along the Y direction, and connects a plurality of transmission columns 451A arranged in the Y direction, and also connects a plurality of reception columns 452A described later. The ± Y side end of the upper electrode 416 is connected to the common electrode line 416A. The common electrode line 416A connects the end portions on the ± Y side of the plurality of upper electrodes 416 arranged along the X direction. Both end portions (± X side end portions) of the common electrode line 416A are located in the terminal region Ar2, and common terminals 416P that are electrically connected to the circuit board 23 are provided. The common terminal 416P is connected to a reference potential circuit (not shown) of the circuit board 23 and set to a reference potential.
In the first ultrasonic transducer 451, when a pulse wave voltage having a predetermined frequency is applied between the first lower electrode 414 and the upper electrode 416, the first flexible portion 412C in the opening region of the first opening 411C is moved. It is vibrated and an ultrasonic wave (fundamental wave) is transmitted from the opening surface 412A side to the + Z side.

(Reception array configuration)
The reception array 462 is provided in a reception area (second area) Ar12 located on the + X side of the transmission area Ar11 in the array area Ar1. The receiving array 462 is the same as the transmitting array 461 except that the ultrasonic transducer 45 has a second ultrasonic transducer 452 that receives the second harmonic, instead of the first ultrasonic transducer 451. Composed. That is, in the receiving array 462, a plurality of second ultrasonic transducers 452 arranged along the X direction constitute a receiving row 452A that functions as one receiving channel, and the plurality of receiving rows 452A are arranged in the Y direction. Is done.

  The second ultrasonic transducer 452 is a vibration region of a vibration film 412 described later, a second flexible part 412D corresponding to the second vibration film, and a second piezoelectric element 417 provided in the second flexible part 412D. And comprising. The second ultrasonic transducer 452 can receive an ultrasonic wave having a frequency according to the dimensions of the second flexible portion 412D in the X direction and the Y direction. In the present embodiment, the second harmonic wave with respect to the fundamental wave. Is configured to be capable of receiving.

  2nd flexible part 412D obstruct | occludes 2nd opening part 411D provided in the board | substrate main-body part 411 among the vibration films | membranes 412 on the back surface 411B side, and comprises a vibration area | region. The second opening 411D is provided at a position corresponding to each second ultrasonic transducer 452 in plan view. The second opening 411D defines the outer edge of the second flexible part 412D. That is, the dimension in the X direction and the Y direction of the second opening 411D is set to a value corresponding to the frequency of the second harmonic. In the present embodiment, for example, the case where the dimension in the Y direction of the second opening 411D is substantially the same as that of the first opening 411C and the dimension in the X direction is approximately one half of the first opening 411C is illustrated. doing.

The second piezoelectric element 417 is provided on the operating surface 412B of the second flexible portion 412D, and is a stacked body of the second lower electrode 418, the second piezoelectric film 419, and the upper electrode 416.
The second lower electrode 418 is formed linearly along the X direction across the plurality of second ultrasonic transducers 452 constituting the 1CH reception row 452A. A second signal terminal 418P that is electrically connected to the circuit board 23 is provided at one end (+ X side end) of the second lower electrode 418.

  In the second ultrasonic transducer 452, when the second flexible portion 412 </ b> D is vibrated by the ultrasonic wave (second harmonic) reflected from the object and incident on the opening surface 412 </ b> A, the second piezoelectric film 419 is vertically moved. A potential difference occurs. Therefore, by detecting the potential difference generated between the second lower electrode 418 and the upper electrode 416, ultrasonic waves are detected, that is, received.

(Configuration of sealing plate)
The sealing plate 42 has a planar shape when viewed from the thickness direction, for example, the same shape as the element substrate 41, and is configured by a semiconductor substrate such as Si or an insulator substrate. Since the material and thickness of the sealing plate 42 affect the frequency characteristics of the ultrasonic 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 ultrasonic transducer 45.

  In the sealing plate 42, a concave groove 421 is formed in a region facing the array region Ar1 of the element substrate 41. That is, the sealing plate 42 has a plurality of concave grooves 421 corresponding to the openings 411C and 411D. As a result, a gap 421A is provided between the element substrate 41 and the sealing plate 42, and the vibrations of the flexible portions 412C and 412D are not hindered. Further, it is possible to suppress inconvenience (crosstalk) in which a back wave from one ultrasonic transducer 45 is incident on another adjacent ultrasonic transducer 45.

  The groove depth of each concave groove 421 may be set to be an odd multiple of 1/4 of the fundamental wavelength in the transmission region Ar11, and in the reception region Ar12, the wavelength of the second harmonic. It may be set to be an odd multiple of ¼. Here, when the vibration film 412 vibrates, an ultrasonic wave is emitted as a back wave on the back surface 411B side as well as on the opening surface 412A side. This back wave is reflected by the sealing plate 42 and is emitted again to the vibrating membrane 412 side through the gap 421A. At this time, by setting the groove depth as described above, the phase of the reflected back wave and the ultrasonic wave emitted from the vibration film 412 to the opening surface 412A can be shifted, and the ultrasonic wave is attenuated. Can do. That is, the thickness dimension of each part of the element substrate 41 and the sealing plate 42 is set in consideration of the wavelength of the ultrasonic wave emitted from the ultrasonic transducer 45.

  In addition, the sealing plate 42 is provided with a connection portion that connects each of the terminals 414P, 416P, and 418P to the circuit board 23 at a position facing the terminal region Ar2 of the element substrate 41. As the connection portion, for example, an opening provided in the element substrate 41, an FPC (Flexible Printed Circuits) that connects each of the terminals 414P, 416P, 418P and the circuit board 23 through the opening, a cable line, a wire, and the like A configuration including a wiring member is exemplified.

(Configuration of acoustic lens)
The acoustic lens 44 is provided on the acoustic layer 43 (+ Z side), which will be described in detail later. As shown in FIG. 1, the acoustic lens 44 is exposed to the outside from the sensor window 21 </ b> B of the housing 21. Further, the acoustic impedance of the acoustic lens 44 is set to an acoustic impedance (for example, 1.5 MRayls) close to the acoustic impedance of the living body. The surface of the acoustic lens 44 on the + Z side is a curved surface that curves toward the + Z side as it goes toward the center (the boundary position between the transmission region Ar11 and the reception region Ar12) along the X direction. The acoustic lens 44 is brought into close contact with the surface of the living body, thereby efficiently converging ultrasonic waves transmitted from the transmission array 461 to a desired position in the living body via the acoustic layer 43, and reflecting in the living body. The transmitted ultrasonic waves are efficiently propagated to the receiving array 462.

  Note that the acoustic lens 44 has a first surface portion 441 that overlaps the transmission area Ar11 and faces the transmission array 461 and a reception area Ar12 out of the −Z side surface in plan view, and faces the reception array 462. A two-surface portion 442. The first surface portion 441 and the second surface portion 442 are parallel to the XY plane, and the second surface portion 442 is located on the −Z side with respect to the first surface portion 441. Thereby, as will be described later, the acoustic layer 43 can be made thinner in the reception area Ar12 than in the transmission area Ar11.

  Examples of a material for forming such an acoustic lens 44 include millable silicone rubber. The millable silicone rubber contains, for example, a silicone rubber having a dimethylpolysiloxane structure containing a vinyl group, silica, and a vulcanizing agent. Specifically, the silica is mixed in the silicone rubber as silica particles having a weight average particle diameter of 15 μm to 30 μm with a mass ratio of 40% by mass to 50% by mass with respect to the silicone rubber. As the vulcanizing agent, for example, 2,5-dimethyl-2,5-ditertiary butyl peroxyhexane can be used.

(Configuration of acoustic layer)
FIG. 5 is a diagram schematically showing the ultrasonic device 22. In FIG. 5, the configuration of the ultrasonic device 22 is simplified, and cross sections of the vibration film 412, the acoustic layer 43, and the acoustic lens 44 of the ultrasonic device 22 are schematically illustrated.
As shown in FIG. 4, the acoustic layer 43 is provided on the + Z side surface of the element substrate 41 (the front surface 411 </ b> A of the substrate body 411 and the opening surface 412 </ b> A of the vibration film 412). The acoustic layer 43, together with the acoustic lens 44, efficiently propagates the ultrasonic wave transmitted from the ultrasonic transducer 45 to the living body to be measured, and efficiently reflects the ultrasonic wave reflected in the living body. Propagate to. For this reason, the acoustic layer 43 is set to an acoustic impedance (for example, 1.0 MRayls) smaller than that of the acoustic lens. As a material having such acoustic impedance, for example, a silicone resin material such as RTV silicone rubber can be used.

  The acoustic layer 43 includes a first acoustic layer 431 laminated on the + Z side of the transmission area Ar11 and a second acoustic layer 432 laminated on the + Z side of the reception area Ar12. That is, the Z direction is the stacking direction of the acoustic layer 43 with respect to the ultrasonic transducer array 46. In the present embodiment, the first acoustic layer 431 and the second acoustic layer 432 are integrally formed of the same material. Therefore, the first acoustic layer 431 and the second acoustic layer 432 have the same ultrasonic velocity and acoustic impedance. Note that the first acoustic layer 431 and the second acoustic layer 432 are not limited to being integrally formed. For example, the boundary position between the transmission area Ar11 and the reception area Ar12 (the position indicated by the one-dot chain line in FIG. 4). ) And may be formed separately.

The dimension L ₁ (thickness dimension and corresponding to the first dimension) in the Z direction of the first acoustic layer 431 is λa / 2 when the wavelength λa of the fundamental wave (wavelength in the acoustic layer 43) is used. For example, the dimensions _{L 1} of the first acoustic layer 431, if the frequency of the transmission wave is set to 5 MHz, is 0.2 mm. Incidentally, _{L 1} is the opening surface 412A (first a surface acoustic layer 431 and the vibrating film 412 first interface F1 (also referred to as reference 5)), the interface of the first acoustic layer 431 and the acoustic lens 44 (hereinafter , And the second interface F2 (also referred to as FIG. 5)).

Thickness _{L 2} of the second acoustic layer 432, when the second harmonic wavelength [lambda] b (wavelength in acoustic layer 43), a [lambda] b / 2. Since λb = λa / 2, the thickness dimension of the second acoustic layer 432 is λa / 4, and L ₂ = L _1/2 . L ₂ is the distance between the interface between the second acoustic layer 432 and the acoustic lens 44 (hereinafter also referred to as a third interface F3 (see FIG. 5)) and the opening surface 412A (first interface F1).

FIG. 6 is a diagram for explaining the action of the acoustic layer 43.
In this embodiment, by setting the thickness dimension L ₁ of the first acoustic layer 431 to be λa / 2 and the thickness dimension L ₂ of the second acoustic layer 432 to be λa / 4, as described below, the measurement accuracy ( (Resolution) can be improved.

Here, a pulse wave voltage is applied to the first ultrasonic transducer 451, and an ultrasonic wave (a transmission wave U0 as a fundamental wave) is transmitted. At this time, as shown in the upper part of FIG. 6, as the transmission wave U0, a dense wave having a plurality of peaks including reverberation is transmitted, and so-called tailing occurs. That is, the reverberation (tailing) portion following the first wave u1 of the transmission wave U0, that is, the reflected wave by the second wave u2 and the third wave u3 is detected, so that the resolution is lowered and the measurement accuracy may be lowered. There is.
Similarly, on the receiving side, there is a possibility that the resolution is reduced due to tailing. That is, as shown in the lower part of FIG. 6, the received wave V0 is also a dense wave having a plurality of peaks including reverberation, and includes the second wave v2 and the third wave v3 as a trailing portion following the first wave v1. . When these tail portions are detected by the second ultrasonic transducer 452, the resolution is lowered and the measurement accuracy may be lowered.
Further, in the present embodiment, when the acoustic impedance is different with the second interface F2 as a boundary, if multiple reflections of ultrasonic waves occur between the first interface F1 and the second interface F2, a plurality of waves corresponding to the multiple reflected waves are generated. Peaks are detected and measurement accuracy may be reduced.

In contrast, in the present embodiment, the dimension _{L 1} of the first acoustic layer 431 and the [lambda] a / 2.
That is, on the transmission side, a part of the transmission wave U0 transmitted from the first ultrasonic transducer 451 and propagating through the first acoustic layer 431 to the + Z side is reflected by the second interface F2 and reflected by the interface reflected wave (hereinafter referred to as the first wave). 1 interface reflected wave U1) occurs. The phase of the first interface reflected wave U1 propagating through the first acoustic layer 431 to the −Z side is inverted when reflected by the first interface F1 (opening surface 412A). Therefore, by setting the thickness dimension of the first acoustic layer 431 to λa / 2, the phase of the first interface reflected wave U1 propagating by one wavelength λa and entering the second interface F2 again is changed at the second interface F2. The phase can be opposite to that of the second wave u2 of the transmission wave U0. Therefore, as shown in the upper diagram of FIG. 6, the trailing portion of the transmission wave U0 after the second wave u2 can be canceled by the first interface reflected wave U1. Therefore, it is possible to suppress a decrease in measurement accuracy due to tailing of the transmission wave.

Furthermore, in the present embodiment, the thickness dimension L ₂ = λb / 2 of the second acoustic layer 432, that is, L ₂ = L _1/2 .
That is, on the receiving side, a part of the received wave (second harmonic) V0 propagating through the second acoustic layer 432 to the −Z side is reflected by the first interface F1 and reflected by the interface (hereinafter referred to as second interface reflection). (Referred to as wave V1). At this time, the phase of the ultrasonic wave is inverted. Therefore, by setting the thickness dimension of the first acoustic layer 431 to λb / 2, the phase of the second interface reflected wave V1 propagating by one wavelength λb in the second acoustic layer 432 and entering the second interface F2 again is changed. The phase of the received wave V0 at the second interface F2 is opposite to that of the second wave v2. As a result, as shown in the lower diagram of FIG. 6, the trailing portion of the received wave V0 after the second wave v2 can be canceled by the second interface reflected wave V1. Therefore, it is possible to suppress a decrease in measurement accuracy due to tailing of the received wave.

Here, when the thickness dimension L ₂ = L ₁ = λb of the second acoustic layer 432, as shown in the lower diagram of FIG. 6, the second interface reflected wave V1 is incident on the first interface F1 again. The propagation distance is two wavelengths. For this reason, the second interface reflected wave V1 cancels out with the third wave v3 of the received wave V0 when reentering the first interface F1. Therefore, the second wave v2 is not canceled and the second wave v2 is received. Therefore, even if the second wave u2 and subsequent parts that are the tailing part can be canceled on the transmission side, only the third wave v3 and subsequent parts of the tailing part can be canceled on the receiving side, which may reduce the resolution.
On the other hand, in this embodiment, by setting the thickness dimension L ₂ = L _{1/2 of} the second acoustic layer 432, not only on the transmitting side but also on the receiving side, the trailing portion after the second wave v2 Can be offset, and a decrease in resolution can be suitably suppressed.

[Effects of First Embodiment]
In the first embodiment configured as described above, the following operational effects can be obtained.
The first dimension _{L 1} of the first acoustic layer 431 is [lambda] a / 2. The second dimension _{L 2} of the second acoustic layer 432, a [lambda] b / 2. Accordingly, when the second ultrasonic transducer 452 receives the second harmonic wave with respect to the ultrasonic wave (fundamental wave) transmitted from the first ultrasonic transducer 451, it is possible to suppress a decrease in resolution.
That is, as described above, for the first dimension L ₁ is a [lambda] a / 2, a first interface reflection waves U1 generated by the second interface F2 of the transmission wave (fundamental wave) U0 is the second interface F2 At the time of re-incident, the phase is delayed by one wavelength with respect to the transmission wave U0, and the phase is reversed. Accordingly, the first interface reflected wave U1 cancels out the second wave u2 and subsequent portions of the reverberation portion of the transmission wave U0.
Meanwhile, since the second dimension L ₂ is [lambda] b / 2, the second interface reflection wave V1 generated in the first interface F1 of the received wave (second harmonic) V0 is reflected by the second interface F2 When re-entering the first interface F1, the phase is delayed by one wavelength with respect to the received wave V0, and the phase is reversed. Therefore, the second interface reflected wave V1 cancels out the second wave v2 and later of the reverberation portion of the received wave V0.
From the above, on both the transmission side and the reception side, it is possible to suppress a decrease in resolution due to detection of an ultrasonic reverberation component, that is, a decrease in resolution due to the influence of tailing, and a decrease in measurement accuracy.

  In the present embodiment, the position of the first surface portion 441 and the second surface portion 442 of the acoustic lens 44 in the Z direction is different. In such a configuration, when the acoustic layer 43 and the acoustic lens 44 are provided on the element substrate 41, the acoustic lens 44 is disposed at an appropriate position (for example, a distance in the Z direction) with respect to the element substrate 41. The thickness dimension of the layer 43 can be set. That is, the first acoustic layer 431 and the first acoustic layer 431 having appropriate thickness dimensions are appropriately set by appropriately setting the distance in the Z direction between the first surface portion 441 and the second surface portion 442 according to the arrangement position of the acoustic lens 44 with respect to the element substrate 41. The two acoustic layers 432 can be easily formed.

[Second Embodiment]
Hereinafter, a second embodiment will be described.
In the first embodiment, the acoustic layer 43 includes a first acoustic layer 431 and a second acoustic layer 432 having a thickness dimension that is half that of the first acoustic layer 431. On the other hand, in the second embodiment, the second acoustic layer is composed of a plurality of layers and is mainly different from the first embodiment in that it has the same thickness dimension as the first acoustic layer 431.
In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

FIG. 7 is a diagram schematically illustrating an ultrasonic device 22A according to the second embodiment.
As shown in FIG. 7, the acoustic lens 44 </ b> A is different from the acoustic lens 44 of the first embodiment in that the array facing surface 443 that is the surface on the −Z side is flat.
The acoustic layer 43 </ b> A includes a first acoustic layer 431 and a second acoustic layer 47.
The second acoustic layer 47 has the same thickness dimension as the first acoustic layer 431, that is, L ₁ (= λa / 2), and the first layer 471 and the second layer stacked on the + Z side of the first layer 471. 472. The first layer 471 and the second layer 472 are formed using, for example, a silicone resin material such as RTV silicone rubber, and the sound velocity of the propagating ultrasonic waves is substantially the same. In the present embodiment, the second layer 472 is formed integrally with the first acoustic layer 431.

  The first layer 471 is filled in the second opening 411D and provided on the second flexible part 412D. The acoustic impedance of the first layer 471 is larger than the acoustic impedance of the second layer 472. For example, the acoustic impedance of the first layer 471 is 1.5 MRayls, and the acoustic impedance of the second layer 472 is 1.0 MRayls. Such a first layer 471 can be formed, for example, by dispersing a filler in a silicone resin material forming the second layer 472, thereby making the acoustic impedance larger than that of the second layer 472.

The thickness dimension of the first layer 471 and the second layer 472 is an odd multiple of λb / 4. The thickness dimension of at least one of the first layer 471 and the second layer 472 is λb / 2 or less.
In the present embodiment, the thickness dimension L ₃ of the first layer 471 is λb / 4, and the thickness dimension L ₄ of the second layer 472 is λb · (3/4). In other words, the thickness dimension L ₃ of the first layer 471 is λa / 8, and the thickness dimension L ₄ of the second layer 472 is λa (3/8). By setting the thickness dimensions of the first layer 471 and the second layer 472 to the above values, the decrease in measurement accuracy due to the above-described tailing is suppressed, and the thickness dimension of the second acoustic layer 47 is changed to the first acoustic layer 431. The same can be done.

FIG. 8 is a diagram for explaining the action of the acoustic layer 43A. In FIG. 8, the configuration of the ultrasonic device 22A is simplified, and cross sections of the vibration film 412, the acoustic layer 43A, and the acoustic lens 44A of the ultrasonic device 22 are schematically illustrated.
In FIG. 8, the interface between the second acoustic layer 47 and the vibration film 412 is a first interface F1, the interface between the second acoustic layer 47 and the acoustic lens 44A is a third interface F3, and the first layer 471 and the second layer. The interface with 472 is referred to as a fourth interface F4. In the present embodiment, when the ultrasonic wave propagating through the first layer 471 is reflected by the first interface F1 and the fourth interface F4, the phase of the ultrasonic wave is inverted.

  As shown in FIG. 8, a part of the received wave V0 incident on the first interface F1 is reflected by the first interface F1 to generate a second interface reflected wave V1. Note that the phase of the received wave is inverted upon reflection at the first interface F1. A part of the second interface reflected wave V1 is reflected by the fourth interface F4 and enters the first interface F1 again. Note that the phase is also inverted when reflected by the fourth interface F4. Therefore, by setting the thickness dimension of the first layer 471 to λb / 4, the phase of the second interface reflected wave V1 propagating through the first layer 471 by half wavelength (λb / 2) and re-entering the first interface F1. Can be out of phase with the first wave v1 of the received wave V0 at the first interface F1. Thereby, at least a part of the second interface reflected wave V1 is canceled with a part of the first wave v1 of the received wave V0 and a trailing part after the second wave v2. Therefore, it is possible to suppress a decrease in measurement accuracy due to tailing of the received wave.

A part of the second interface reflected wave V1 generated at the first interface F1 is reflected by the third interface F3 and is incident on the first interface F1 again. Since the thickness dimension of the second acoustic layer 47 is an integral multiple of λb / 2, the phase of the second interface reflected wave V1 can be opposite to the phase of the received wave V0, and the second interface reflected wave V1 is generated by the received wave V0. Can be offset.
Further, a part of the received wave V0 is reflected by the fourth interface F4, and a third interface reflected wave V2 is generated. The third interface reflected wave V2 is reflected by the third interface F3 and enters the fourth interface F4 again. By setting the thickness dimension of the second layer 472 to an odd multiple of λb / 4, the phase of the third interface reflected wave V2 can be opposite to the phase of the received wave V0, and the third interface reflected wave V2 is changed by the received wave V0. Can be offset.
Therefore, it is possible to suppress a decrease in measurement accuracy due to reception of the interface reflected wave.

[Effects of Second Embodiment]
In the second embodiment configured as described above, the following operational effects can be obtained.
The first dimension _{L 1} of the first acoustic layer 431 is lambda / 2. The second acoustic layer 47 includes a first layer 471 and a second layer 472. The third dimension _{L 3} of the first layer 471 is a λb / 4 (= λa / 8 ), is [lambda] b / 2 or less. The thickness L ₄ of the second layer 472 is λb · (3/4) = λa (3/8). As a result, as in the first embodiment, the resolution can be improved when the second ultrasonic transducer 452 receives the second harmonic with respect to the transmission wave (fundamental wave).

That is, on the transmission side, as in the first embodiment, the second and subsequent waves in the reverberation part of the transmission wave U0 are canceled by the first interface reflected wave U1.
On the other hand, on the receiving side, the second interface reflected wave V1 reflected by the first interface F1 out of the received wave V0 that is the second harmonic is reflected by the third interface F3 and the fourth interface F4, Again, when the light enters the first interface F1, the phase is opposite to that of the received wave V0 and cancels out. Of the received wave V0, the third interface reflected wave V2 reflected by the fourth interface F4 is reflected by the third interface F3 and then incident on the fourth interface F4 again. The phase is reversed and cancelled.
Here, the dimension _{L 3} of the first layer 471 is [lambda] b / 2 or less. For this reason, at least the second wave v2 or later of the reverberation part of the received wave V0 can be canceled by the second interface reflected wave V1 reflected between the first interface F1 and the fourth interface F4 and propagating through the first layer 471.
From the above, similarly to the transmission side, it is possible to suppress a decrease in resolution due to the detection of the second and subsequent waves of the reverberation component on the reception side, that is, a decrease in measurement accuracy due to the influence of tailing.

The thickness dimensions of the first acoustic layer 431 and the second acoustic layer 47 are the same. Thereby, the interface with each acoustic layer 431 and 47 of acoustic lens 44A provided over the 1st acoustic layer 431 and the 2nd acoustic layer 47 can be made into a plane, and the composition of acoustic lens 44A can be simplified.
Further, the dimensions _{L 3} of the first layer 471 and [lambda] b / 4, the dimension _{L 4} of the second layer 472 by a [lambda] b · (3/4), while suppressing the influence of the tail, the first acoustic The dimension of the layer 431 and the dimension of the second acoustic layer 47 can be made the same.

Further, the depth dimension of the second opening 411D of the substrate body 411 (Z dimension), and the thickness _{L 3} of the first layer 471, forming the first layer 471 in the second opening 411D . Thereafter, the first acoustic layer 431 and the second layer 472 are formed at the same time, and the acoustic lens 44 is disposed, whereby the ultrasonic device 22A can be formed. Thereby, it is easy to set the thickness of the first layer 471 to an appropriate dimension. The first acoustic layer 431 and the second layer 472 can be formed at the same time, and the manufacturing process can be simplified as compared with the case where they are manufactured separately.

  Further, by making the thickness dimension of the first layer 471 smaller than that of the second layer 472, it is easy to increase the reception sensitivity. In other words, the first layer 471 is a layer having a larger acoustic impedance than the second layer 472 layer. Such a first layer 471 can be easily formed by diffusing a filler using the same material as the forming material of the second layer 472 as described above. Therefore, the reception sensitivity can be increased by making the thickness of the second layer 472 having a smaller attenuation coefficient than that of the first layer 471 larger than that of the first layer 471. In addition, the acoustic layer 43A including the first layer 471 and the second layer 472 can be easily formed as described above. From the above, it is easy to increase the reception sensitivity.

[Modification]
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.

(Modification 1)
In the first embodiment, the first dimension _{L 1} of the first acoustic layer 431 and [lambda] a / 2, but the second dimension _{L 2} of the second acoustic layer 432 was set to [lambda] b / 2, but is not limited thereto. For example, the first dimension _{L 1} may be an integer n times [lambda] a / 2 (the following formula (1) see). Also, the second dimension _{L 2} of the second acoustic layer 432 may be an integer n times [lambda] b / 2 (see the following formula (2)). Even in such a configuration, when the wavelengths of the ultrasonic waves are different between the transmission wave and the reception wave, it is possible to suppress a decrease in measurement accuracy due to the influence of tailing being different between the transmission side and the reception side.

[Equation 1]
L ₁ = (λa / 2) · n (1)
L ₂ = (λb / 2) · n (2)

That is, as described above, the first interface reflected wave U1 generated at the second interface F2 in the transmission wave U0 propagating through the first acoustic layer 431 is reflected at the first interface F1, and then again the second interface. Incident to F2. At this time, since the first dimension _{L 1} is a (λa / 2) · n, the propagation distance of the first interface reflection waves U1 is a [lambda] a · n round trip of the first acoustic layer 431. For this reason, at the second interface F2, the phase of the first interface reflected wave U1 is delayed by 2nπ with respect to the transmission wave U0 and has an opposite phase. Therefore, the first and following reflected waves cancel out the (n + 1) th and subsequent waves in the reverberation part of the transmission wave U0.

On the other hand, the second interface reflected wave V1 generated at the first interface F1 in the received wave V0 that is a reflected wave from the measurement object is reflected at the third interface F3 and then enters the first interface F1 again. At this time, since the second dimension _{L 2} is (λb / 2) · n, similarly, the phase of the second interface reflection wave V1 at the first interface F1, to the received wave V0, delayed by 2n [pi], And it becomes an antiphase. Therefore, the portion after the (n + 1) th wave in the reverberation portion of the received wave V0 is canceled.

  As described above, by setting the thicknesses of the first acoustic layer 431 and the second acoustic layer 432 according to the corresponding wavelengths, it is possible to detect the (n + 1) th and subsequent waves on both the transmission side and the reception side. Can be suppressed. Therefore, even when the transmission wave and the reception wave are different, as in the case of receiving high-order harmonics with respect to the transmission wave, it is possible to suppress a decrease in measurement accuracy due to the difference in tailing between the transmission side and the reception side. .

(Modification 2)
In the second embodiment, the first dimension L ₁ of the first acoustic layer 431 is λa / 2, the third dimension L ₃ of the first layer 471 is λb / 4, that is, λb / 2 or less, and the second layer 472 a fourth dimension _{L 4} was λa · (3/8). However, it is not limited to this. For example, the first dimension _{L 1} is an integer n multiple of [lambda] a / 2 (the above formula (1)), the dimension of the first layer 471 and second layer 472 is an odd multiple of [lambda] b / 4, and the first At least one dimension of the layer 471 and the second layer 472 may be an integer n times or less of λb / 2. Even in such a configuration, when the wavelengths of the ultrasonic waves are different between the transmission wave and the reception wave, it is possible to suppress a decrease in measurement accuracy due to the influence of tailing being different between the transmission side and the reception side.

That is, the first dimension L ₁ by an integral multiple of [lambda] a / 2 (e.g., n times), the first n + 1 wave onward first interface reflection wave of the reverberant part of the transmission wave U0 of the first acoustic layer 431 Offset by U1.
On the other hand, when the dimensions of the first layer 471 and the second layer 472 are odd multiples of λb / 4, the second interface reflected wave V1 is re-incident on the first interface F1 as in the second embodiment. Therefore, it is canceled out in the opposite phase to the received wave V0. Further, when the third interface reflected wave V2 reenters the fourth interface F4, the third interface reflected wave V2 has an opposite phase to the received wave V0 and cancels out.

  Here, the dimension of at least one of the first layer 471 and the second layer 472 is an integer n times or less of λb / 2. For this reason, at least one of the second interface reflected wave V1 and the third interface reflected wave V2 has a propagation distance of λb · n or less, a delay amount of 2nπ or less, and an opposite phase with respect to the received wave. For this reason, at least the (n + 1) th and subsequent waves in the reverberation part of the received wave V0 is canceled by at least one of the second interface reflected wave V1 and the third interface reflected wave V2.

  From the above, it is possible to suppress the detection of the (n + 1) th wave and thereafter on both the transmission side and the reception side. Therefore, even when the transmission wave and the reception wave are different, as in the case of receiving high-order harmonics with respect to the transmission wave, it is possible to suppress a decrease in measurement accuracy due to the difference in tailing between the transmission side and the reception side. .

(Other variations)
In 1st Embodiment, although the thickness dimension of the 2nd acoustic layer 432 illustrated the structure larger than the depth dimension of 2nd opening part 411D, it is not limited to this, The depth dimension of 2nd opening part 411D is used. The thickness dimension of the second acoustic layer 432 may be used. Thereby, it is easy to adjust the thickness of the second acoustic layer 432. Similarly, the depth dimension of the first opening 411C may be the thickness dimension of the first acoustic layer 431.

  In the second embodiment, the configuration in which the dimension of the first layer 471 is smaller than that of the second layer 472 is exemplified. However, the present invention is not limited to this, and the size of the first layer 471 may be larger than that of the second layer 472. For example, the dimension of the first layer 471 may be λb · (3/4), and the dimension of the second layer 472 may be λb / 4. Even with such a configuration, the influence of tailing can be suppressed as in the second embodiment.

In each of the embodiments described above, the acoustic layer is disposed so as to cover the opening surface 412 </ b> A side of the vibration film 412, that is, the substrate body 411. However, the present invention is not limited to this, and the acoustic layer may be provided on the side opposite to the substrate body 411 so as to cover the operation surface 412B of the vibration film 412.
FIG. 9 is a cross-sectional view schematically showing an ultrasonic device 22B according to a modification.
As shown in FIG. 9, the ultrasonic device 22 </ b> B includes an element substrate 41, a sealing plate 42 </ b> B disposed on the −Z side of the element substrate 41, an acoustic layer 43 and an acoustic layer disposed on the + Z side of the element substrate 41. A lens 44. In the ultrasonic device 22B, the vibration film 412 is provided on the + Z side of the substrate body 411. That is, the −Z side surface of the vibration film 412 is the opening surface 412A, and the + Z side surface is the operation surface 412B. A first piezoelectric element 413 and a second piezoelectric element 417 are provided on the operating surface 412B. The sealing plate 42 </ b> B is formed in a flat plate shape, and is provided on the −Z side of the element substrate 41 so as to face the substrate body 411.
The configuration other than the above is basically the same as that of the first embodiment.

In each of the above embodiments, the case where the first acoustic layer and the second acoustic layer have the same sound speed of the ultrasonic waves has been described, but the present invention is not limited to this. For example, the sound speed may be different between the first acoustic layer and the second acoustic layer.
Moreover, although each said embodiment illustrated the structure which receives the 2nd harmonic with respect to a transmission wave, it is not limited to this. For example, the second ultrasonic transducer may be capable of receiving third and higher order higher harmonics. Even in such a case, by setting the thickness dimension of each layer of the acoustic layer according to the corresponding wavelength, it is possible to suppress a decrease in measurement accuracy due to the difference in tailing between the transmission side and the reception side.

  In each of the above embodiments, the ultrasonic transducer array 46 including the first ultrasonic transducer 451 for transmission and the second ultrasonic transducer 452 for reception is illustrated, but the present invention is not limited to this. That is, both the first ultrasonic transducer 451 and the second ultrasonic transducer 452 may be configured to be capable of transmitting and receiving ultrasonic waves. That is, the first ultrasonic transducer 451 may transmit and receive ultrasonic waves, and the second ultrasonic transducer 452 may transmit and receive ultrasonic waves. Thus, even if an ultrasonic transducer array that transmits and receives ultrasonic waves having different frequencies (wavelengths) is formed on the same substrate, a decrease in the resolution of each ultrasonic transducer array can be suppressed.

  In each of the above embodiments, the transmission array 461 and the reception array 462 are each configured as a one-dimensional array in which transmission channels or reception channels are arranged in one direction, but the present invention is not limited to this. For example, each channel that can be individually driven may be configured as a two-dimensional array arranged in a matrix. In this case, instead of the acoustic lens, a protective film having a larger acoustic impedance than the acoustic layer is disposed on the acoustic layer. Even in such a configuration, it is possible to suppress a decrease in measurement accuracy due to a difference in tailing between the transmission side and the reception side.

  In each of the above embodiments, the ultrasonic transducer 45 includes a configuration including a vibration film and a piezoelectric element formed on the vibration film. However, the configuration is not limited thereto. For example, the ultrasonic transducer 45 includes a flexible film, a first electrode provided on the flexible film, and a second electrode provided at a position facing the first electrode on the sealing plate. It may be adopted. The first electrode and the second electrode constitute an electrostatic actuator as a vibrator. In such a configuration, an ultrasonic wave can be transmitted by driving the electrostatic actuator, and an ultrasonic wave can be detected by detecting a capacitance between the electrodes.

  In each of the above-described embodiments, the electronic apparatus is exemplified as an ultrasonic device whose measurement target is an organ in a living body, but is not limited thereto. For example, the structure of the said embodiment and each modification is applicable to the measuring machine which performs the detection of the defect of the said structure, and the test | inspection of aging for various structures. Further, for example, the same applies to a measuring machine that uses a semiconductor package, a wafer, or the like as a measurement target and detects a defect of 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 device, 2 ... Ultrasonic probe, 10 ... Control apparatus, 21 ... Housing, 22, 22A, 22B ... Ultrasonic device, 41 ... Element substrate, 42 ... Sealing plate, 43, 43A ... Acoustic layer 44, 44A ... acoustic lens, 45 ... ultrasonic transducer, 46 ... ultrasonic transducer array, 411 ... substrate body, 411A ... front, 411B ... back, 411C ... first opening, 411D ... second opening. 412 ... Vibration membrane, 412A ... Opening surface, 412B ... Operating surface, 412C ... First flexible part, 412D ... Second flexible part, 413 ... First piezoelectric element, 414 ... First lower electrode, 415 ... First Piezoelectric film, 416 ... upper electrode, 417 ... second piezoelectric element, 418 ... second lower electrode, 419 ... second piezoelectric film, 421 ... concave groove, 421A ... gap, 431 ... first acoustic layer, 432 ... second acoustic layer, 41 ... first surface portion, 442 ... second surface portion, 451 ... first ultrasonic transducer, 452 ... second ultrasonic transducer, 461 ... transmitting array, 462 ... receiving array, 471 ... first layer, 472 ... second Layer, Ar1... Array area, Ar11... Transmission area, Ar12.

Claims (9)

An ultrasonic transducer array having a first region in which a first ultrasonic transducer having a first vibrating membrane is provided and a second region in which a second ultrasonic transducer having a second vibrating membrane is provided;
A first acoustic layer stacked on the first region of the ultrasonic transducer array;
A second acoustic layer stacked in the second region of the ultrasonic transducer array;
An acoustic lens provided across the first acoustic layer and the second acoustic layer and having a larger acoustic impedance than the first acoustic layer and the second acoustic layer,
In the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, the first dimension of the first acoustic layer is the wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer in the first acoustic layer λa. And an integer n times λa / 2,
In the stacking direction, the second dimension of the second acoustic layer is n times λb / 2 where λb is the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer. Ultrasonic device featuring. The ultrasonic device according to claim 1,
The first dimension is λa / 2,
Said 2nd dimension is (lambda) b / 2. The ultrasonic device characterized by the above-mentioned. An ultrasonic transducer array having a first region in which a first ultrasonic transducer having a first vibrating membrane is provided and a second region in which a second ultrasonic transducer having a second vibrating membrane is provided;
A first acoustic layer stacked on the first region of the ultrasonic transducer array;
A second acoustic layer stacked in the second region of the ultrasonic transducer array;
An acoustic lens provided across the first acoustic layer and the second acoustic layer and having a larger acoustic impedance than the first acoustic layer and the second acoustic layer,
The second acoustic layer includes a first layer on the ultrasonic transducer array side, and a second layer located on the opposite side of the ultrasonic transducer array and having an acoustic impedance smaller than that of the first layer. Have
In the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, the first dimension of the first acoustic layer is λa / 2, where λa is the wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer. An integer n times,
In the stacking direction, the dimensions of the first layer and the second layer are an odd multiple of λb / 4, where λb is the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer. ,
The size of at least one of the first layer and the second layer is not more than n times λb / 2. The ultrasonic device according to claim 3.
The ultrasonic device, wherein the first acoustic layer and the second acoustic layer have the same dimensions. The ultrasonic device according to claim 3 or 4,
The first dimension is λa / 2,
One dimension of the said 1st layer and the said 2nd layer is (lambda) b / 4. The ultrasonic device characterized by the above-mentioned. An ultrasonic transducer array having a first region in which a first ultrasonic transducer having a first vibrating membrane is provided and a second region in which a second ultrasonic transducer having a second vibrating membrane is provided;
A first acoustic layer stacked on the first region of the ultrasonic transducer array;
A second acoustic layer stacked in the second region of the ultrasonic transducer array;
An acoustic lens provided across the first acoustic layer and the second acoustic layer and having a larger acoustic impedance than the first acoustic layer and the second acoustic layer;
A housing for housing the ultrasonic transducer array, the first acoustic layer, the second acoustic layer, and the acoustic lens;
In the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, the first dimension of the first acoustic layer is the wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer in the first acoustic layer λa. And an integer n times λa / 2,
In the stacking direction, the second dimension of the second acoustic layer is n times λb / 2 where λb is the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer. Characteristic ultrasonic probe. An ultrasonic transducer array having a first region in which a first ultrasonic transducer having a first vibrating membrane is provided and a second region in which a second ultrasonic transducer having a second vibrating membrane is provided;
A first acoustic layer stacked on the first region of the ultrasonic transducer array;
A second acoustic layer stacked in the second region of the ultrasonic transducer array;
An acoustic lens provided across the first acoustic layer and the second acoustic layer and having a larger acoustic impedance than the first acoustic layer and the second acoustic layer;
A housing for housing the ultrasonic transducer array, the first acoustic layer, the second acoustic layer, and the acoustic lens;
The second acoustic layer includes a first layer on the ultrasonic transducer array side, and a second layer located on the opposite side of the ultrasonic transducer array and having an acoustic impedance smaller than that of the first layer. Have
In the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, the first dimension of the first acoustic layer is λa / 2, where λa is the wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer. An integer n times,
In the stacking direction, the dimensions of the first layer and the second layer are an odd multiple of λb / 4, where λb is the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer. ,
The ultrasonic probe according to claim 1, wherein a dimension of at least one of the first layer and the second layer is not more than n times λb / 2. An ultrasonic transducer array having a first region in which a first ultrasonic transducer having a first vibrating membrane is provided and a second region in which a second ultrasonic transducer having a second vibrating membrane is provided;
A first acoustic layer stacked on the first region of the ultrasonic transducer array;
A second acoustic layer stacked in the second region of the ultrasonic transducer array;
An acoustic lens provided across the first acoustic layer and the second acoustic layer and having a larger acoustic impedance than the first acoustic layer and the second acoustic layer;
A control unit for controlling the first ultrasonic transducer and the second ultrasonic transducer,
In the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, the first dimension of the first acoustic layer is the wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer in the first acoustic layer λa. And an integer n times λa / 2,
In the stacking direction, the second dimension of the second acoustic layer is n times λb / 2 where λb is the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer. Ultrasonic device characterized. An ultrasonic transducer array having a first region in which a first ultrasonic transducer having a first vibrating membrane is provided and a second region in which a second ultrasonic transducer having a second vibrating membrane is provided;
A first acoustic layer stacked on the first region of the ultrasonic transducer array;
A second acoustic layer stacked in the second region of the ultrasonic transducer array;
An acoustic lens provided across the first acoustic layer and the second acoustic layer and having a larger acoustic impedance than the first acoustic layer and the second acoustic layer;
A control unit for controlling the first ultrasonic transducer and the second ultrasonic transducer,
The second acoustic layer includes a first layer on the ultrasonic transducer array side, and a second layer located on the opposite side of the ultrasonic transducer array and having an acoustic impedance smaller than that of the first layer. Have
In the stacking direction of the first acoustic layer with respect to the ultrasonic transducer array, the first dimension of the first acoustic layer is λa / 2, where λa is the wavelength of the ultrasonic wave transmitted by the first ultrasonic transducer. An integer n times,
In the stacking direction, the dimensions of the first layer and the second layer are an odd multiple of λb / 4, where λb is the wavelength of the ultrasonic wave received by the second ultrasonic transducer in the second acoustic layer. ,
The size of at least one of the first layer and the second layer is not more than n times λb / 2.

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