WO2015152044A1

WO2015152044A1 - Ultrasonic vibrator and manufacturing method therefor

Info

Publication number: WO2015152044A1
Application number: PCT/JP2015/059601
Authority: WO
Inventors: 片山　真吾; 飯島　竜太
Original assignee: ブラザー工業株式会社
Priority date: 2014-03-31
Filing date: 2015-03-27
Publication date: 2015-10-08
Also published as: JP2015195517A; JP5971274B2

Abstract

Provided are an ultrasonic vibrator which enables the adjustment of a resonance frequency and the prevention of output leakage of ultrasonic vibration, and a manufacturing method therefor. In a cylindrical casing (5), at least part of a vibration part (2) configured by integrally forming an acoustic lens (4) and a piezoelectric element (3) is disposed in a peripheral wall part (51). The outer diameter (D2) of the acoustic lens (4) is slightly smaller than the inner diameter (D3) of the peripheral wall part (51). At an end (51B) of the peripheral wall part (51), an enlarged diameter part (55) configured by broadening an inner peripheral surface (51C) outward in a radial direction is formed. An adhesive (6) is provided in the enlarged diameter part (55). The cured adhesive (6) elastically holds the vibration part (2) in the casing (5) while maintaining the vibration part (2) and the casing (5) in a noncontact state. The acoustic impedance of the adhesive (6) is lower than those of the acoustic lens (4) and the casing (5). The ultrasonic vibration of the piezoelectric element (3) does not easily propagate to the casing (5) via the adhesive (6). Further, an ultrasonic vibrator (1) enables the resonance frequency of the acoustic lens (4) by adjusting the amount of the adhesive (6).

Description

Ultrasonic vibrator and manufacturing method thereof

The present invention relates to an ultrasonic transducer that oscillates upon input of an electric signal and outputs ultrasonic waves, and a method for manufacturing the same.

A probe for an ultrasonic inspection apparatus is known in which a transducer that converts electrical signals into ultrasonic waves and an acoustic lens that outputs the ultrasonic waves generated by the transducers to the outside are fixed to a case. (For example, refer to Patent Document 1). The probe described in Patent Document 1 has a structure in which an acoustic lens that adheres to a vibrator is fixed to an opening end of a case with an adhesive, and the case is filled with a filler such as silicon rubber.

Japanese Utility Model Publication No. 2-172

However, Patent Document 1 has a structure in which the filler fills the space in the case. Therefore, there is a problem that the filler presses the acoustic lens in the case, and the resonance frequency of the acoustic lens is deviated from a target frequency and fixed to a specific frequency. Further, Patent Document 1 has a problem that ultrasonic vibration output leakage occurs from the case because the vibration of the acoustic lens is propagated to the case through the filler.

An object of the present invention is to provide an ultrasonic transducer capable of adjusting the resonance frequency and preventing output leakage of ultrasonic vibration and a method for manufacturing the ultrasonic transducer.

According to the first aspect of the present invention, a vibration unit that integrally fixes a piezoelectric element that oscillates upon input of an electrical signal and generates ultrasonic waves, and an acoustic lens that outputs the ultrasonic waves generated by the piezoelectric elements to the outside. And a housing in which at least a part of the vibrating part is disposed inside in a state where a gap is opened between the vibrating part and the vibrating part in a crossing direction intersecting a displacement direction in which the piezoelectric element is displaced. An adhesive that is provided at a portion where the outer surface and the inner surface of the housing face each other, fixes the position of the vibrating portion relative to the housing, and maintains the vibrating portion and the housing in a non-contact state; An ultrasonic transducer is provided.

Generally, a casing used for an ultrasonic transducer has high rigidity and an acoustic impedance that is relatively close to that of an acoustic lens. In the first aspect, since the adhesive maintains the casing and the vibration part in a non-contact state, the ultrasonic wave generated in the vibration part is filled with the adhesive filling the space in the casing. Since the region where the vibration of the vibration part is propagated to the housing is smaller than in the case, it is difficult to propagate to the housing. Therefore, the ultrasonic transducer can prevent the output leakage of the ultrasonic vibration from the casing. Further, when the adhesive is cured, the adhesive is supported in a state where the vibration part is stretched in the housing. When the pressing force with which the adhesive presses the vibrating portion changes according to the amount of the adhesive, the acoustic impedance of the acoustic lens changes. Therefore, the adhesive can change the resonance frequency of the acoustic lens according to the amount of use. Therefore, the ultrasonic transducer can adjust the resonance frequency of the acoustic lens to an arbitrary frequency.

In the first aspect, at least one first recess having a depth outward in the intersecting direction may be formed on the inner surface of the housing at a portion facing the outer surface of the vibrating part in the intersecting direction. . In this case, the adhesive may be filled in the first recess. When the adhesive is injected into the gap, the first recess functions as an adhesive reservoir by filling the first recess, so that the amount of the adhesive can be easily adjusted. Therefore, the ultrasonic transducer can easily adjust the resonance frequency of the acoustic lens to an arbitrary frequency.

In the first aspect, the first concave portion may be formed in a groove shape extending over one circumference on the inner surface of the housing. Since the first recess extends in the shape of a groove, the adhesive can support the vibrating portion without deviation in one round in the gap. Therefore, the ultrasonic transducer of the first aspect is easy to adjust without causing individual differences in the adjustment of the resonance frequency of the acoustic lens.

1st aspect WHEREIN: At least 1 or more 2nd recessed part dented in the said cross direction inward may be formed in the site | part which faces the inner surface of the said housing | casing in the said cross direction among the outer surfaces of the said vibration part. In this case, the adhesive may be filled in the second recess. When the adhesive is injected into the gap, the second recess functions as an adhesive reservoir by filling the second recess, so that the amount of the adhesive can be easily adjusted. Therefore, the ultrasonic transducer can easily adjust the resonance frequency of the acoustic lens to an arbitrary frequency.

In the first aspect, the diameter of the inscribed circle in the cross section of the acoustic lens orthogonal to the displacement direction may be larger than the diameter of the circumscribed circle in the cross section of the piezoelectric element orthogonal to the displacement direction. Since the diameter of the circumscribed circle of the cross section of the piezoelectric element is smaller than the diameter of the inscribed circle of the cross section of the acoustic lens, the adhesive is used when injecting the adhesive into the gap between the inner surface of the housing and the outer surface of the acoustic lens. It is difficult to adhere to the piezoelectric element. Therefore, the ultrasonic transducer is easy to reliably adjust the resonance frequency of the acoustic lens to an arbitrary frequency.

1st aspect WHEREIN: The said vibration part may be arrange | positioned in the said housing | casing in the state which at least one part protruded from the said housing | casing in the said displacement direction. The vibration unit includes a plurality of protrusions protruding outward in the cross direction at a portion protruding from the end of the housing in the displacement direction, of the outer surface orthogonal to the cross direction of the vibration unit. Also good. In this case, the length of the plurality of protrusions may be larger than the size of the gap in the intersecting direction. When the vibration part is arranged in the housing, the protrusion protrudes larger than the gap, so that the vibration part is prevented from being caught in the housing and falling into the housing. Furthermore, the protrusion can form a gap between the inner surface of the housing and the outer surface of the vibration portion, and can maintain this state. Therefore, if an adhesive is injected into the gap, after curing, the adhesive can support the vibrating part in the casing while maintaining the vibrating part and the casing in a non-contact state.

According to a second aspect of the present invention, there is provided a method for manufacturing an ultrasonic transducer according to the first aspect, wherein at least a part of the vibrating portion is disposed inside the casing, and the casing A positioning step for positioning the vibrating part and the housing in a state where the gap is opened between the vibrating part and the vibrating part, and a position where the outer surface of the vibrating part and the inner surface of the housing face each other in the crossing direction A first injection step of injecting a predetermined first amount of the adhesive, a temporary curing step of curing the adhesive in a temporary cured state, and an output waveform with respect to an input waveform input to the vibration unit, A measurement step of measuring a resonance frequency of the acoustic lens, a determination step of determining whether the resonance frequency of the acoustic lens measured in the measurement step is less than a predetermined frequency, and the acoustic lens determined in the determination step Together When the frequency is less than the predetermined frequency, a second amount of the adhesive smaller than the first amount is injected into a portion where the outer surface of the vibration part and the inner surface of the housing face each other in the intersecting direction. After the second injection step and the second injection step are performed, the temporary curing step, the measurement step, and the determination step are performed again. In the determination step, the measurement is performed in the measurement step. And a main curing step of completely curing the adhesive when it is determined that the resonance frequency of the acoustic lens is not less than the predetermined frequency. .

Measure the resonant frequency of the acoustic lens while injecting a second amount of adhesive into the gap and adjusting the amount of adhesive used, the resonant frequency of the acoustic lens can be gradually brought closer to a predetermined frequency. Therefore, if the ultrasonic transducer is manufactured according to the manufacturing method according to the second aspect, the resonance frequency of the acoustic lens can be adjusted to an arbitrary frequency.

1 is a perspective view of an ultrasonic transducer 1. FIG. 1 is a plan view of an ultrasonic transducer 1. FIG. FIG. 4 is a cross-sectional view of the ultrasonic transducer 1 as viewed from the direction of the arrows along the one-dot chain line AA in FIG. 3 is a flowchart showing a manufacturing process of the ultrasonic transducer 1. 2 is a plan view of an ultrasonic transducer 101. FIG. FIG. 6 is a cross-sectional view of the ultrasonic transducer 101 as viewed from the direction of the arrows along the one-dot chain line BB in FIG. 2 is a plan view of an ultrasonic transducer 201. FIG. FIG. 8 is a cross-sectional view of the ultrasonic transducer 201 as viewed from the direction of the arrows along the one-dot chain line CC in FIG. 7.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings to be referred to are used for explaining technical features that can be adopted by the present invention. The configuration of the apparatus described in the drawings, the flowchart showing the manufacturing process, and the like are not intended to be limited to this, but are merely illustrative examples.

The structure of the ultrasonic transducer 1 according to this embodiment will be described with reference to FIGS. The ultrasonic transducer 1 is an element that refracts and converges an ultrasonic wave generated by the piezoelectric element 3 that oscillates when an electric signal is input, and outputs it to the outside. The ultrasonic transducer 1 is used, for example, in a probe (probe) of an ultrasonic diagnostic apparatus. In the following description, the axis of the casing 5 of the ultrasonic transducer 1 is P, and the axis P is a reference for explaining the positional relationship, orientation, and direction of each part constituting the ultrasonic transducer 1. And In the extending direction of the axis P (hereinafter referred to as “axis P direction”), the side (upper side in FIG. 3) on which the vibration unit 2 is disposed with respect to the housing 5 is the front end side of the ultrasonic transducer 1 and is opposite to it. The side is the rear end side.

The ultrasonic transducer 1 includes a cylindrical housing 5 extending in the axis P direction. The housing 5 is formed using, for example, an engineering plastic having heat resistance, and generally has high rigidity. The casing 5 is connected to a cylindrical peripheral wall portion 51 that surrounds the periphery of the axis P, and an end 51A on the front end side of the peripheral wall portion 51, and a circular plate-shaped bottom wall portion 52 that has the thickness direction in the direction of the axis P. Have The outer diameter of the peripheral wall 51 is, for example, 6.4 mm (Φ6.4, hereinafter abbreviated as well), and the inner diameter D3 is, for example, Φ5.45. The thickness of the peripheral wall part 51 and the thickness of the bottom wall part 52 are substantially the same. The peripheral wall 51 has a length in the axis P direction that is shorter than the diameter of the bottom wall 52. In the center of the bottom wall portion 52, a circular opening 53 (see FIG. 3) penetrating in the thickness direction is formed. The inner diameter of the opening 53 is smaller than the inner diameter of the peripheral wall 51. A jig (not shown) for supporting the vibrating unit 2 in the housing 5 when the vibrating unit 2 is fixed to the housing 5 in the manufacturing process of the ultrasonic vibrator 1 described later is an opening in the bottom wall 52. It is inserted into the housing 5 through 53. A circular hole 54 that penetrates the peripheral wall 51 in the radial direction is formed at the end 51 A of the peripheral wall 51. A lead wire (not shown) connected to the piezoelectric element 3 for inputting an electric signal is inserted into the hole portion 54 of the peripheral wall portion 51 and drawn out of the housing 5.

The end portion 51B on the rear end side of the peripheral wall portion 51 is formed with an enlarged diameter portion 55 in which the inner peripheral surface 51C of the peripheral wall portion 51 is expanded radially outward. The enlarged diameter portion 55 is formed as a recess in the inner peripheral surface 51C of the peripheral wall portion 51 over the entire circumference in the circumferential direction, thereby forming a stepped groove shape. The inner peripheral surface 55C of the peripheral wall portion 51 in the enlarged diameter portion 55 is connected to the end surface 51D on the rear end side of the peripheral wall portion 51, and forms a ridge corner portion with the end surface 51D. The inner diameter of the peripheral wall portion 51 in the enlarged diameter portion 55 is, for example, Φ5.8. That is, the inner peripheral surface 55 C of the enlarged diameter portion 55 is positioned approximately 2 mm outside in the radial direction with respect to the inner peripheral surface 51 C of the peripheral wall portion 51. The length of the inner peripheral surface 55C in the axis P direction is approximately 1/2 to 1/3 of the length of the acoustic lens 4 (described later) in the axis P direction. The end surface 55D of the peripheral wall portion 51 in the enlarged diameter portion 55 connects the inner peripheral surface 51C of the peripheral wall portion 51 and the inner peripheral surface 55A of the enlarged diameter portion 55 in a step shape. The length in the radial direction of the end face 55D is approximately 1/2 to 1/3 of the length in the radial direction of the peripheral wall portion 51. The enlarged diameter portion 55 functions as an adhesive reservoir that prevents an adhesive 6 (described later) applied between the housing 5 and the vibration portion 2 (described later) from dripping into the housing 5.

The ultrasonic transducer 1 includes a vibrating unit 2 that is disposed at least partially within the housing 5. The vibration part 2 is a component in which the piezoelectric element 3 and the acoustic lens 4 are integrally fixed. The piezoelectric element 3 is an element whose size changes in a predetermined direction by applying a voltage. The shape of the piezoelectric element 3 is a disk shape having a direction in which the size changes (hereinafter referred to as “displacement direction”) as a thickness direction. The outer diameter D1 of the piezoelectric element 3 is, for example, Φ5.0. For the piezoelectric element 3, for example, PZT (lead zirconate titanate) is used. As the piezoelectric element 3, for example, PVDF (polyvinylidene fluoride) may be used. The outer diameter D1 of the piezoelectric element 3 is smaller than the outer diameter D2 of the acoustic lens 4 (described later). When the vibration unit 2 is disposed in the housing 5 and held by the adhesive 6 (described later), the adhesive 6 is piezoelectric by making the outer diameter D1 of the piezoelectric element 3 smaller than the outer diameter D2 of the acoustic lens 4. Adhering to the element 3 can be avoided. The piezoelectric element 3 is fixed integrally with the acoustic lens 4 and constitutes the vibration unit 2. The vibration unit 2 is fixed to the housing 5 in a state where the displacement direction of the piezoelectric element 3 is aligned with the axis P direction. The piezoelectric element 3 vibrates by being displaced according to the strength of the input electric signal, and generates an ultrasonic wave.

The acoustic lens 4 is a cylindrical part extending in the axis P direction. The outer diameter D2 of the acoustic lens 4 is, for example, Φ5.4. The acoustic lens 4 is formed using, for example, an engineering plastic having heat resistance. The length of the acoustic lens 4 in the axis P direction is shorter than the length of the peripheral wall 51 of the housing 5 in the axis P direction. In the acoustic lens 4, a lens portion 42 that is curved in a concave shape toward the rear end side is formed on the end surface 41 on the front end side, leaving an edge portion of the end surface 41. The lens unit 42 refracts and focuses the ultrasonic waves generated by the piezoelectric element 3. The end surface 43 on the rear end side of the acoustic lens 4 is formed with a recess 44 in which a part of the end surface 43 is recessed in a circular shape toward the front end side. In the acoustic lens 4, a part of the piezoelectric element 3 is disposed in the recess 44. The acoustic lens 4 and the piezoelectric element 3 are fixed integrally to form the vibration unit 2. Note that the acoustic impedance of the acoustic lens 4 is a value close to the acoustic impedance of the housing 5. The outer diameter D2 of the acoustic lens 4 is slightly smaller than the inner diameter D3 of the peripheral wall portion 51 of the housing 5. Therefore, when the vibration unit 2 is disposed in the housing 5, a slight gap can be formed between the inner peripheral surface 51 C of the peripheral wall portion 51 and the outer peripheral surface 45 of the acoustic lens 4.

The housing 5 and the vibration part 2 are fixed with an adhesive 6 (see FIG. 3). As the adhesive 6, for example, an adhesive having thermosetting property and elasticity and having an acoustic impedance after curing lower than the acoustic impedance of the acoustic lens 4 and the housing 5 is used. The difference between the acoustic impedance of the adhesive 6 and the acoustic impedance of the acoustic lens 4 and the housing 5 is preferably as large as possible. At least a part of the vibration unit 2 is disposed in the housing 5 with a gap between the inner peripheral surface 51 C of the peripheral wall portion 51 and the outer peripheral surface 45 of the acoustic lens 4. Specifically, in the vibration unit 2, the outer peripheral surface 45 of the acoustic lens 4 is formed on the peripheral wall portion 51 of the housing 5 in the housing 5 with the lens portion 42 facing the front end side. It arrange | positions in the position facing 55 C of internal peripheral surfaces. Therefore, a part of the front end side of the acoustic lens 4 is located on the front end side in the axis P direction with respect to the end surface 51D on the front end side of the peripheral wall portion 51 of the housing 5. In other words, the end surface 41 on the front end side of the acoustic lens 4 is located on the front end side in the axis P direction with respect to the end surface 51D of the peripheral wall portion 51. The adhesive 6 is provided in the enlarged diameter portion 55 in a state where the gap between the inner peripheral surface 51C of the peripheral wall portion 51 and the outer peripheral surface 45 of the acoustic lens 4 is maintained. The cured adhesive 6 elastically holds the vibration part 2 in the housing 5 while maintaining the vibration part 2 and the housing 5 in a non-contact state. In other words, the vibration unit 2 is held in a state suspended in the housing 5 by the adhesive 6.

As described above, the ultrasonic transducer 1 has a structure in which the vibrating portion 2 is held in a non-contact manner by the adhesive 6 in the housing 5. The ultrasonic vibration generated when the piezoelectric element 3 generates ultrasonic waves does not directly propagate from the acoustic lens 4 to the housing 5 but indirectly through the adhesive 6. The adhesive 6 is provided only in a portion where the outer peripheral surface 45 of the acoustic lens 4 and the inner peripheral surface 51 C of the peripheral wall portion 51 face the acoustic lens 4 and the housing 5. Therefore, the region where ultrasonic vibration is propagated to the housing 5 via the adhesive 6 is smaller than when the adhesive 6 fills the space in the housing 5. Therefore, the ultrasonic vibration is difficult to propagate from the acoustic lens 4 to the housing 5. Furthermore, the ultrasonic transducer 1 uses an adhesive having an acoustic impedance lower than that of the acoustic lens 4 and the housing 5 as the adhesive 6. That is, in the ultrasonic transducer 1, the adhesive 6 having an acoustic impedance different from the acoustic impedance of the acoustic lens 4 and the housing 5 is interposed between the acoustic lens 4 and the housing 5. Thereby, the ultrasonic vibration propagating from the acoustic lens 4 to the housing 5 is likely to be reflected at the interface between the acoustic lens 4 and the adhesive 6 and the interface between the adhesive 6 and the housing 5 and is difficult to transmit. . Therefore, the ultrasonic vibrator 1 can suppress propagation of ultrasonic vibration from the acoustic lens 4 to the housing 5 via the adhesive. Therefore, the ultrasonic transducer 1 can prevent the output leakage of the ultrasonic vibration from the housing 5 to the outside.

Further, the adhesive 6 is cured to support the acoustic lens 4 in a state in which the acoustic lens 4 is stretched inward in the radial direction within the housing 5. The pressing force with which the adhesive 6 presses the acoustic lens 4 in the housing 5 increases as the area where the adhesive 6 presses the outer peripheral surface 45 of the acoustic lens 4 increases. That is, the pressing force of the adhesive 6 against the acoustic lens 4 increases as the amount of the adhesive 6 provided in the enlarged diameter portion 55 increases. The acoustic lens 4 increases in internal stress when the pressing force received from the adhesive 6 increases. The acoustic lens 4 has a high resonance frequency when the internal stress increases. Therefore, the ultrasonic transducer 1 can adjust the resonance frequency of the acoustic lens 4 to an arbitrary frequency according to the amount of the adhesive 6 provided in the enlarged diameter portion 55.

In the present embodiment, in the manufacturing process of the ultrasonic transducer 1, the resonance frequency of the acoustic lens 4 is changed by changing the amount of the adhesive 6 injected into the enlarged diameter portion 55 while measuring the resonance frequency of the acoustic lens 4. Is adjusted to a desired frequency. In the manufacturing process of the ultrasonic transducer 1, the resonance frequency of the acoustic lens 4 is adjusted as described below.

As shown in FIG. 4, in the manufacturing process of the ultrasonic vibrator 1, first, the vibration unit 2 and the housing 5 manufactured in separate processes are attached to a jig (not shown), and the vibration unit 2 and the housing are assembled. 5 is positioned (S1). The jig holds the casing 5 with the front end side facing upward. The jig includes a holding member (not shown) that extends in the vertical direction and holds the vibrating unit 2 in a state where the vibrating unit 2 is disposed at the top. The holding member is inserted into the housing 5 from below through the opening 53 of the bottom wall portion 52 of the housing 5. The vibration unit 2 is inserted into the housing 5 from above the housing 5 with the acoustic lens 4 side facing upward, and is disposed on the holding member. The holding member holds the vibration unit 2, a part of the front end side of the acoustic lens 4 is positioned above the end surface 51 D of the peripheral wall portion 51 of the housing 5, and the outer peripheral surface 45 and the peripheral wall portion of the acoustic lens 4. The state of having a gap between the inner peripheral surface 51C of 51 and the inner peripheral surface 51C is maintained.

Next, the adhesive 6 is applied between the housing 5 and the vibration part 2 (S2). Application of the adhesive 6 is performed by pouring a first prescribed amount into the enlarged diameter portion 55 with a known dispenser (not shown). The first specified amount is an amount of the adhesive 6 determined in advance by experiments or the like as an amount that can reduce the resonance frequency of the acoustic lens 4 to a desired frequency or less after the adhesive 6 is cured. The adhesive 6 has a viscosity that does not fall down along a gap (a size of, for example, 0.025 mm) between the inner peripheral surface 51C of the peripheral wall portion 51 of the housing 5 and the outer peripheral surface 45 of the acoustic lens 4. Good. The adhesive 6 is injected into the enlarged diameter portion 55 over one circumference in the circumferential direction. In the present embodiment, when the first prescribed amount of the adhesive 6 is applied and cured, the first prescribed amount is reset to be smaller when the resonance frequency of the acoustic lens 4 becomes higher than the desired frequency. Alternatively, the housing 5 is redesigned so that the size of the enlarged diameter portion 55 (for example, the inner diameter of the peripheral wall portion 51 in the enlarged diameter portion 55) is increased. Thereby, after applying the first specified amount of the adhesive 6 and curing, the resonance frequency of the acoustic lens 4 can be set to a desired frequency or less.

Next, the adhesive 6 is temporarily cured (S3). The temporarily cured state of the adhesive 6 is a state where the adhesive force is lower than that in the fully cured state, but substantially the same elastic force as that in the fully cured state is obtained. As the adhesive 6, for example, an adhesive that is temporarily cured by heating at a temperature lower than that at the time of main curing is used. Alternatively, the adhesive 6 may be used that is in a fully cured state by heat treatment and in a temporarily cured state by irradiation with UV light.

Next, the resonance frequency of the acoustic lens 4 is measured (S4). The resonance frequency is measured using a known impedance analyzer (not shown). An impedance analyzer is a device that can measure the resonance frequency of a measurement object based on an output waveform output from the measurement object with respect to an input waveform input to the measurement object. When the measured frequency is lower than the frequency desired as the resonance frequency of the acoustic lens 4 (S5: NO), a second specified amount of adhesive 6 is additionally applied between the housing 5 and the vibrating portion 2. (S6). The second specified amount is an amount capable of obtaining a pressing force that can make the resonance frequency of the acoustic lens 4 higher by a predetermined frequency (for example, about 10 to 1 kHz) than the frequency before the additional application after the adhesive 6 is cured. The amount of the adhesive 6 determined in advance through experiments or the like. If the second specified amount of adhesive 6 is additionally applied, the process returns to S3. The additionally applied adhesive 6 is temporarily cured (S3), and the resonance frequency of the acoustic lens 4 is measured again (S4).

As long as the measured frequency does not reach the desired frequency as the resonance frequency of the acoustic lens 4, the adhesive 6 is additionally applied by the second specified amount, and the measurement of the resonance frequency is repeated. When the resonance frequency of the acoustic lens 4 reaches a desired frequency (S5: YES), the adhesive 6 is fully cured (S7). The ultrasonic vibrator 1 is heated at a predetermined temperature, and the adhesive 6 is in a fully cured state. The adhesive 6 fixes the vibration unit 2 in the housing 5 and elastically holds the vibration unit 2 in the housing 5 while maintaining the vibration unit 2 and the housing 5 in a non-contact state. The manufacturing process of the ultrasonic transducer 1 ends.

As described above, generally, the casing 5 used for the ultrasonic transducer 1 has high rigidity, and the acoustic impedance exhibits a value relatively close to that of the acoustic lens 4. Since the adhesive 6 maintains the housing 5 and the vibration part 2 in a non-contact state, the ultrasonic wave generated in the vibration part 2 is filled with the adhesive 6 filling the space in the housing 5. Therefore, since the region where the vibration of the vibration unit 2 is propagated to the housing 5 is small, it is difficult to propagate to the housing 5. Therefore, the ultrasonic vibrator 1 can prevent the occurrence of ultrasonic vibration output leakage from the housing 5. Further, when the adhesive 6 is cured, the adhesive 6 is supported in a state where the vibrating portion 2 is stretched in the housing 5. When the pressing force with which the adhesive 6 presses the vibrating portion 2 changes according to the amount of the adhesive 6, the acoustic impedance of the acoustic lens 4 changes. Therefore, the adhesive 6 can change the resonance frequency of the acoustic lens 4 according to the amount of use. Therefore, the ultrasonic transducer 1 can adjust the resonance frequency of the acoustic lens 4 to an arbitrary frequency.

Further, when the adhesive 6 is injected into the gap between the outer peripheral surface 45 of the acoustic lens 4 and the inner peripheral surface 51C of the peripheral wall portion 51, the expanded diameter portion 55 is bonded by filling the expanded diameter portion 55. Since it functions as a reservoir for the agent 6, it is easy to adjust the amount of the adhesive 6. Therefore, the ultrasonic vibrator 1 can easily adjust the resonance frequency of the acoustic lens 4 to an arbitrary frequency.

In addition, since the enlarged diameter portion 55 extends in a groove shape in the circumferential direction on the inner peripheral surface 51C of the peripheral wall portion 51, the adhesive 6 can support the vibrating portion 2 without deviation in one round in the gap. Therefore, the ultrasonic transducer 1 is easy to adjust without causing individual differences in adjusting the resonance frequency of the acoustic lens 4.

Further, since the outer diameter D1 of the piezoelectric element 3 is smaller than the outer diameter D2 of the acoustic lens 4, the adhesive 6 is a gap between the inner peripheral surface 51C of the peripheral wall portion 51 of the housing 5 and the outer peripheral surface 45 of the acoustic lens 4. When the adhesive 6 is injected into the inside, it is difficult to adhere to the piezoelectric element 3. Therefore, the ultrasonic transducer 1 is easy to reliably adjust the resonance frequency of the acoustic lens 4 to an arbitrary frequency.

Further, in the manufacturing process of the ultrasonic vibrator 1, the second predetermined amount of the adhesive 6 is injected into the gap while measuring the resonance frequency of the acoustic lens 4, and the usage amount of the adhesive 6 is adjusted to thereby adjust the acoustic amount. The resonance frequency of the lens 4 can be gradually brought close to a predetermined frequency. Therefore, if the ultrasonic transducer 1 is manufactured according to the manufacturing process of the present embodiment, the resonance frequency of the acoustic lens 4 can be adjusted to an arbitrary frequency.

Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the housing 5 is not limited to a cylindrical shape, and may be a rectangular tube shape, a box shape, or the like. The acoustic lens 4 is not limited to a cylindrical shape, and may be a prismatic shape, a rectangular parallelepiped shape, or the like. The piezoelectric element 3 is not limited to a disk shape but may be a rectangular plate shape. In this case, the diameter of the circumscribed circle of the cross section orthogonal to the axis P direction of the piezoelectric element 3 may be smaller than the diameter of the inscribed circle of the cross section orthogonal to the axis P direction of the acoustic lens 4. When holding the vibration part 2 with the adhesive 6 in the housing 5, it is possible to avoid the adhesive 6 from adhering to the piezoelectric element 3. In addition, the vibration unit 2 may be integrated by fixing a plurality of piezoelectric elements 3 to the acoustic lens 4. Even in this case, the diameter of the circumscribed circle in the region orthogonal to the axis P and provided with the plurality of piezoelectric elements 3 only needs to be smaller than the diameter of the inscribed circle in the cross section orthogonal to the axis P of the acoustic lens 4.

Further, like the ultrasonic transducer 101 shown in FIGS. 5 and 6, the acoustic lens 104 may include a plurality of protrusions 146 protruding outward in the radial direction on the outer peripheral surface 145. In addition, the structure of the piezoelectric element 3 (refer FIG. 5) which is fixed integrally with the acoustic lens 104 and forms the vibration part 102, and the housing | casing 5 are the same as that of this embodiment. The plurality of protrusions 146 are provided on the outer peripheral surface 145 of the acoustic lens 104 at equal positions in the circumferential direction, for example, at three positions. The protrusion 146 is provided on the front end side in the axis P direction on the outer peripheral surface 145 of the acoustic lens 104. The protruding portion 146 protrudes from the outer peripheral surface 145 by the length substantially the same as the length in the radial direction of the end surface 55D of the enlarged diameter portion 55. With this configuration, when the vibrating portion 2 and the housing 5 are positioned in the manufacturing process of the ultrasonic transducer 101, the protruding tip of the protruding portion 146 is in contact with or close to the inner peripheral surface 55C of the enlarged diameter portion 55, respectively. To do. Therefore, the ultrasonic transducer 101 can easily maintain a state where there is a gap between the outer peripheral surface 145 of the acoustic lens 104 and the inner peripheral surface 51C of the peripheral wall portion 51. Note that it is preferable that the number of the protrusions 146 be three or more because the center line of the acoustic lens 104 can be brought closer to the axis P in the housing 5 more reliably. Further, the protrusion 146 protrudes greatly from the outer peripheral surface 145 in the radial direction than the gap between the outer peripheral surface 145 of the acoustic lens 104 and the inner peripheral surface 51 C of the peripheral wall portion 51. Therefore, when the vibration part 102 is disposed in the housing 105, the protrusion 146 is caught on the end surface 55 D of the diameter-enlarged part 55. Therefore, when the acoustic lens 104 is disposed in the housing 5, the protrusion 146 is formed on the diameter-enlarged portion 55 even if the jig holding member (not shown) does not hold the vibrating portion 102. By coming into contact with the end surface 55D, the vibration unit 102 can be prevented from falling into the housing 5. In this state, if an adhesive is injected into the enlarged diameter portion 55, after curing, the adhesive 6 keeps the vibrating portion 102 and the housing 105 in a non-contact state while maintaining the vibrating portion in the housing 105. 102 can be supported.

Further, like the ultrasonic transducer 201 shown in FIGS. 7 and 8, a reduced diameter portion 247 in which the outer peripheral surface 245 is narrowed radially inward over the entire circumference may be formed on the front end side of the acoustic lens 204. . An outer peripheral surface 247 C of the acoustic lens 204 in the reduced diameter portion 247 is connected to the end surface 241 on the front end side, and forms a ridge corner portion with the end surface 241. An end surface 247D on the front end side of the acoustic lens 204 in the reduced diameter portion 247 connects the outer peripheral surface 245 of the acoustic lens 204 and the outer peripheral surface 247C of the reduced diameter portion 247 in a stepped manner. In the ultrasonic transducer 201, the diameter-reduced portion 247 is formed in the acoustic lens 204, so that the diameter-enlarged portion may not be formed in the peripheral wall portion 251 of the housing 205. In a state where at least a part of the vibration unit 202 is disposed in the housing 205, at least a part of the outer peripheral surface 247 C of the reduced diameter portion 247 of the acoustic lens 204 faces the inner peripheral surface 251 C of the peripheral wall 251 of the housing 205. It is arranged at the position to do. Thereby, a gap into which the adhesive 6 can be injected can be formed between the outer peripheral surface 247C of the reduced diameter portion 247 and the inner peripheral surface 251C of the peripheral wall portion 251 and the reduced diameter portion 247 functions as an adhesive reservoir. be able to. Even if the ultrasonic vibrator 201 is configured in this way, the cured adhesive 6 is elastic in the casing 205 while maintaining the vibrating section 202 and the casing 205 in a non-contact state. Can be held in. As described above, when filling the gap between the acoustic lens 204 and the housing 205, the reduced diameter portion 247 functions as an adhesive reservoir by filling the reduced diameter portion 247. Therefore, the amount of the adhesive 6 is reduced. Easy to adjust. Therefore, the ultrasonic transducer 1 can easily adjust the resonance frequency of the acoustic lens 204 to an arbitrary frequency.

In the manufacturing process of the ultrasonic vibrator 1, the resonance frequency of the acoustic lens 4 is adjusted by increasing the amount of the adhesive 6 applied. For example, the resonance frequency is adjusted by trimming and reducing the temporarily cured adhesive 6. May be. Moreover, although the adhesive agent 6 was provided over the circumferential direction perimeter in the enlarged diameter part 55, you may apply | coat partially and provide it. In this case, the position where the adhesive 6 is provided may be equal in the circumferential direction. In this case, the adhesive 6 may be applied to at least three positions in the circumferential direction.

Moreover, although the enlarged diameter part 55 was provided over the perimeter of the circumferential direction of the surrounding wall part 51, you may provide partially. In this case, the position where the enlarged diameter portion 55 is provided may be a uniform position in the circumferential direction. In this case, the enlarged diameter portion 55 is preferably provided at at least three positions in the circumferential direction. Further, the enlarged diameter portion 55 is formed in a stepped groove shape between the end surface 51D and the inner peripheral surface 51C on the inner peripheral surface 51C of the peripheral wall portion 51, but is not connected to the end surface 51D, and the inner peripheral surface. A groove shape may be formed in 51C.

In the present embodiment, the end surface 41 on the front end side of the acoustic lens 4 is positioned closer to the front end side in the axis P direction than the end surface 51D of the peripheral wall portion 51, but may be the same position or the rear end in the axis P direction. It may be located on the side. In the housing 5, the outer peripheral surface 45 of the acoustic lens 4 can be disposed at a position facing the inner peripheral surface 55 C of the enlarged diameter portion 55, and the bonding is performed while maintaining the gap between the acoustic lens 4 and the housing 5. It is only necessary that the acoustic lens 4 and the housing 5 can be fixed by the agent 6. Furthermore, the outer peripheral surface 45 of the acoustic lens 4 may not be disposed so as to oppose the entire inner peripheral surface 55C of the enlarged diameter portion 55, and is opposed to at least a predetermined position on the inner peripheral surface 55C where the adhesive 6 is provided. As long as it can be arranged.

In the present invention, the enlarged diameter portion 55 corresponds to a “first concave portion”. The reduced diameter portion 247 corresponds to a “second concave portion”. The outer peripheral surface 45 corresponds to “the outer surface of the vibrating portion”, and the inner peripheral surface 51C corresponds to “the inner surface of the housing”. In the manufacturing process, the step S1 corresponds to a “positioning step”, and the step S2 corresponds to a “first injection step”. The first specified amount corresponds to the “first amount”. The step S3 corresponds to a “temporary curing step”, and the step S4 corresponds to a “measurement step”. The step S5 corresponds to a “determination step”, and the step S6 corresponds to a “second injection step”. The second specified amount corresponds to the “second amount”. The process of S7 corresponds to the “main curing process”.

1, 101, 201

Ultrasonic vibrator

2, 102, 202 Vibrating unit 3

Piezoelectric element

4, 104, 204

Acoustic lens

5, 205 Housing 6

Adhesives

45, 145, 245 Outer

peripheral surface

51C, 251C Inner peripheral surface 55 Diameter expansion 146 Projection 247 Reduced diameter part D1 Outer diameter D2 Outer diameter

Claims

A vibration part that integrally oscillates when an electric signal is input and generates an ultrasonic wave and an acoustic lens that outputs the ultrasonic wave generated by the piezoelectric element to the outside;
A housing in which at least a part of the vibration part is disposed inside with a gap between the vibration part and the vibration part;
The vibration element is provided at a portion where the outer surface of the vibration unit and the inner surface of the housing face each other in a crossing direction intersecting a displacement direction in which the piezoelectric element is displaced, and fixes the position of the vibration member with respect to the housing, and the vibration An ultrasonic transducer comprising: an adhesive that maintains a portion and the casing in a non-contact state.
On the inner surface of the housing, at least one or more first recesses having a depth outward in the intersecting direction are formed in a portion facing the outer surface of the vibrating portion in the intersecting direction,
The ultrasonic transducer according to claim 1, wherein the adhesive is filled in the first recess.
3. The ultrasonic transducer according to claim 2, wherein the first concave portion is formed in a groove shape extending over the entire inner surface of the housing.
Of the outer surface of the vibration part, at least one or more second recesses recessed inward in the intersecting direction are formed in a portion facing the inner surface of the housing in the intersecting direction,
The ultrasonic transducer according to claim 1, wherein the adhesive is filled in the second recess.
The diameter of the circumscribed circle of the cross section of the acoustic lens orthogonal to the displacement direction is larger than the diameter of the circumscribed circle of the cross section of the piezoelectric element orthogonal to the displacement direction. Sonic transducer.
The vibrating portion is disposed in the casing with at least a portion protruding from the casing in the displacement direction,
The vibration unit includes a plurality of protrusions protruding outward in the intersecting direction at a portion protruding in the displacement direction from an end of the housing among the outer surfaces orthogonal to the intersecting direction of the vibration unit,
The ultrasonic transducer according to claim 1, wherein a length of the plurality of protrusions is larger than a size of the gap in the intersecting direction.
It is a manufacturing method of the ultrasonic vibrator according to claim 1,
Positioning step of positioning at least a part of the vibration part inside the housing and positioning the vibration part and the housing in a state where the housing and the vibration part are opened with the gap. When,
A first injection step of injecting a predetermined first amount of the adhesive into a portion where the outer surface of the vibration part and the inner surface of the housing face each other in the crossing direction;
A temporary curing step of curing the adhesive in a temporary cured state;
Based on an output waveform with respect to an input waveform input to the vibration unit, a measurement step of measuring a resonance frequency of the acoustic lens;
A determination step of determining whether a resonance frequency of the acoustic lens measured in the measurement step is less than a predetermined frequency;
When the resonance frequency of the acoustic lens determined in the determination step is less than the predetermined frequency, the first amount is closer to a portion where the outer surface of the vibration unit and the inner surface of the housing face each other in the intersecting direction. A second injection step of injecting a second amount of the adhesive with a small amount,
After the second injection step is performed, the temporary curing step, the measurement step, and the determination step are performed again,
The determination step includes a main curing step of completely curing the adhesive when it is determined that the resonance frequency of the acoustic lens measured in the measurement step is not less than the predetermined frequency. A method for manufacturing an ultrasonic transducer.