Ultrasonic transducer and method for manufacturing the same

Abstract

A flexible printed circuit board (140) includes a first surface section (141), a second surface section (142) and a third surface section (143). The first surface section (141) has a first electrode (145) electrically connected to a piezoelectric element (120), and extends so as to contact a first main surface (121) of the piezoelectric element (120). The second surface section (142) curves and stands upright from the edge of the first surface section (141) near a lateral wall section (112) of a case (110), and extends along said lateral wall section (112). The third surface section (143) has a second electrode (146) electrically connected to a first end section (131) of a terminal member (130), curves in an S-shape from the upper end of the second surface section (142), and faces the first surface section (141) with an interval interposed therebetween. The first surface section (141) and at least the section of the second surface section (142) which is near the first surface section (141) are embedded in a first filler material (150).

Description

Technical Field

[0001] The present invention relates to an ultrasonic transducer and a method for manufacturing the same.

Background Art

[0002] As a prior art document that discloses the configuration of an ultrasonic sensor, there is International Publication No. 2013 / 051525 (Patent Document 1). The ultrasonic sensor described in Patent Document 1 includes a case, a piezoelectric element, pin terminals, a strip-shaped flexible substrate, and a vibration damping material. The case has a bottom plate and side walls. The piezoelectric element is disposed on the bottom plate within the case. One tip of the pin terminal is disposed within the opening of the case, and the other tip is disposed outside the case. The flexible substrate has a first end connected to one tip of the pin terminal and a second end connected to the piezoelectric element. The vibration damping material seals one tip of the pin terminal within the case and the flexible substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the ultrasonic sensor described in Patent Document 1, a part of the flexible printed board near the piezoelectric element is disposed directly above the piezoelectric element. In this case, this part of the flexible printed board may inhibit the absorption of ultrasonic vibrations oscillated from the piezoelectric element by the filling material filled within the case. Therefore, there is room for improving the acoustic characteristics of the ultrasonic sensor by sufficiently absorbing the ultrasonic vibrations by the filling material.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide an ultrasonic transducer and a method for manufacturing the same, in which the acoustic characteristics are improved by allowing the filler material to sufficiently absorb ultrasonic vibrations. [Means for solving the problem]

[0006] The ultrasonic transducer according to the present invention comprises a bottomed cylindrical case, a piezoelectric element, a terminal member, a strip-shaped flexible printed circuit board, a first filler, and a second filler. The case has a bottom and a side wall. The piezoelectric element has a first main surface and a second main surface, with the second main surface attached to the bottom inside the case. The terminal member has a first end located inside the case and a second end located outside the case. The flexible printed circuit board electrically connects the piezoelectric element and the first end of the terminal member. The first filler is filled so as to fill the bottom side inside the case. The second filler is filled so as to fill the first filler inside the case. The flexible printed circuit board includes a first surface, a second surface, and a third surface. The first surface has a first electrode electrically connected to the piezoelectric element and extends while in contact with the first main surface of the piezoelectric element. The second surface curves up from the edge adjacent to the side wall of the first surface and extends along the side wall of the case. The third surface has a second electrode electrically connected to the first end of the terminal member, and is bent in an S-shape from the upper end of the second surface, with a gap between it and the first surface. The first surface and at least the portion of the second surface closer to the first surface are embedded in the first filler material. [Effects of the Invention]

[0007] According to the present invention, the acoustic characteristics of an ultrasonic transducer can be improved by allowing the filler material to sufficiently absorb ultrasonic vibrations. [Brief explanation of the drawing]

[0008] [Figure 1] This is a longitudinal cross-sectional view of an ultrasonic transducer according to Embodiment 1 of the present invention. [Figure 2]This is a flowchart showing a method for manufacturing an ultrasonic transducer according to Embodiment 1 of the present invention. [Figure 3] This is a cross-sectional view showing the state in which the piezoelectric element and the flexible printed circuit board of the ultrasonic transducer according to Embodiment 1 of the present invention are connected. [Figure 4] This is a longitudinal cross-sectional view showing the piezoelectric element of the ultrasonic transducer according to Embodiment 1 of the present invention attached to the bottom of the case. [Figure 5] This is a longitudinal cross-sectional view showing the state in which the first filler material of the ultrasonic transducer according to Embodiment 1 of the present invention is filled inside the case. [Figure 6] This is a longitudinal cross-sectional view showing a state in which a terminal member of an ultrasonic transducer according to Embodiment 1 of the present invention is connected to a flexible printed circuit board. [Figure 7] This is a longitudinal cross-sectional view showing the state in which the first end of the terminal member is positioned inside the case by bending the flexible printed circuit board of the ultrasonic transducer according to Embodiment 1 of the present invention. [Figure 8] This is a longitudinal cross-sectional view of an ultrasonic transducer according to Embodiment 2 of the present invention. [Modes for carrying out the invention]

[0009] The ultrasonic transducers according to each embodiment of the present invention will be described below with reference to the figures. In the following description of the embodiments, the same or corresponding parts in the figures will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0010] In the drawings, the direction along the bottom of the case is referred to as the DR1 direction, and the direction of the case's height is referred to as the DR2 direction.

[0011] (Embodiment 1) Figure 1 is a longitudinal cross-sectional view of an ultrasonic transducer according to Embodiment 1 of the present invention. As shown in Figure 1, the ultrasonic transducer 100 according to this embodiment is, for example, an ultrasonic sensor.

[0012] As shown in FIG. 1, the ultrasonic transducer 100 includes a bottomed cylindrical case 110, a piezoelectric element 120, a terminal member 130, a strip-shaped flexible printed circuit board 140, a first filler 150, and a second filler 160.

[0013] The case 110 has a bottom portion 111 and a side wall portion 112. The bottom portion 111 of the present embodiment has a disc shape when viewed from the DR2 direction. The diameter of the bottom portion 111 is, for example, 14.0 mm or more and 15.5 mm or less. Note that the shape of the bottom portion 111 is not limited to a disc shape, and may be a rectangular plate shape or a polygonal plate shape.

[0014] The side wall portion 112 extends upward from the peripheral edge of the bottom portion 111. The height H1 of the case 110 from the outer bottom surface of the bottom portion 111 located on the outer surface of the case 110 to the upper end of the side wall portion 112 is, for example, 9.0 mm.

[0015] The case 110 is made of a conductive material. In the present embodiment, the case 110 is made of, for example, an aluminum alloy. However, the material constituting the case 110 is not limited to a conductive material, and may be an insulating material. The case 110 is formed, for example, by forging.

[0016] The piezoelectric element 120 includes a piezoelectric body made of, for example, ceramics. In the present embodiment, the piezoelectric body included in the piezoelectric element 120 is made of PZT (lead zirconate titanate) - based ceramics. However, the piezoelectric body included in the piezoelectric element 120 is not limited to PZT - based ceramics, and may be other piezoelectric materials.

[0017] By attaching the piezoelectric element 120 to the bottom portion 111, a unimorph - type piezoelectric vibrator is formed. Note that the piezoelectric element 120 may be a bimorph - type piezoelectric vibrator or a multimorph - type piezoelectric vibrator.

[0018] The piezoelectric element 120 is provided with a pair of electrodes (not shown). When a voltage is applied to the pair of electrodes, the piezoelectric element 120 is driven to vibrate. When the piezoelectric element 120 vibrates, the bottom portion 111 vibrates.

[0019] Also, when the bottom portion 111 of the case 110 vibrates by receiving ultrasonic waves from the outside, the piezoelectric element 120 also vibrates along with this vibration. By generating electric charges along with the vibration of the piezoelectric element 120, the ultrasonic waves are converted into electrical signals by the piezoelectric element 120. The electrical signal is transmitted to the outside through the pair of electrodes.

[0020] As shown in FIG. 1, in the ultrasonic transducer 一百において according to the present embodiment, the piezoelectric element 120 is disposed at a position substantially in the center in the DR1 direction of the case 110.

[0021] The piezoelectric element 120 includes a first main surface 121 and a second main surface 122. The first main surface 121 and the second main surface 122 face each other. The second main surface 122 is attached to the bottom portion 111 inside the case 110. In the present embodiment, the piezoelectric element 120 is adhered to the bottom portion 111 with an epoxy resin.

[0022] In the DR1 direction, the ratio of the width of the internal space of the case 110 to the width of the piezoelectric element 120 is 1.1 times or more. Due to this ratio relationship, the piezoelectric element 120 can be attached to the bottom portion 111 of the case 110 without applying an overload to the flexible printed board 140 described later.

[0023] The terminal member 130 in the present embodiment is a pin terminal. The terminal member 130 includes a first end portion 131, a second end portion 132, and a support member 133.

[0024] The first end 131 is located inside the case 110. The second end 132 is located outside the case 110. A support member 133 supports the first end 131 and the second end 132. Each of the first end 131, the second end 132, and the support member 133 is made of a conductive material.

[0025] The flexible printed circuit board 140 electrically connects the piezoelectric element 120 to the first end 131 of the terminal member 130. The flexible printed circuit board 140 is provided with electrical wiring for applying voltage to the piezoelectric element 120 and signal lines for transmitting electrical signals generated in the piezoelectric element 120.

[0026] The flexible printed circuit board 140 includes a first surface 141, a second surface 142, and a third surface 143.

[0027] The first surface portion 141 extends while in contact with the first main surface 121 of the piezoelectric element 120. The first surface portion 141 extends along the DR1 direction.

[0028] The first surface portion 141 has a first electrode 145 that is electrically connected to the piezoelectric element 120. The first electrode 145 is connected, for example, by soldering to the first main surface 121 of the piezoelectric element 120.

[0029] The second surface portion 142 curves upward from the edge of the first surface portion 141 that is close to the side wall portion 112, and extends along the side wall portion 112 of the case 110. In this embodiment, the second surface portion 142 is in direct contact with the side wall portion 112. The second surface portion 142 may extend along the side wall portion 112 while leaving a gap between it and the side wall portion 112. In addition, although the second surface portion 142 in this embodiment is mainly composed of a straight shape, it may be curved in a range such that the piezoelectric element 120 and the second surface portion 142 do not align in the DR2 direction.

[0030] In this embodiment, the flexible printed circuit board 140 near the piezoelectric element 120 has a portion that is fixed linearly within the case 110, making it easy to position the flexible printed circuit board 140. This suppresses variations in the position of the first filler material 150, which fills a portion of the flexible printed circuit board 140 as described later. As a result, variations in the sound absorption characteristics of the first filler material 150 that absorb ultrasonic vibrations emitted from the piezoelectric element 120 can be suppressed, and thus variations in the acoustic characteristics of the ultrasonic transducer 100 with respect to ultrasonic vibrations can be suppressed.

[0031] The curvature R of the second surface portion 142 at the boundary with the edge of the first surface portion 141 in the flexible printed circuit board 140 is between 0.8 (1 / mm) and 2.9 (1 / mm). This suppresses overloading of the portion at the boundary between the first surface portion 141 and the second surface portion 142, and allows the second surface portion 142 to be in direct contact with and along the side wall portion 112.

[0032] The third surface portion 143 is bent in an S-shape from the upper end of the second surface portion 142 and faces the first surface portion 141 at a distance from it. The third surface portion 143 is bent in an S-shape along the DR1 direction. However, the third surface portion 143 is not limited to an S-shape; it may also be a straight line along the DR1 direction, or a meandering shape, etc.

[0033] The third surface portion 143 has a second electrode 146 that is electrically connected to the first end portion 131 of the terminal member 130. The second electrode 146 is connected, for example, by soldering to the first end portion 131 of the terminal member 130.

[0034] The first electrode 145 and the second electrode 146 are arranged on either the front or back surface of the flexible printed circuit board 140. In this embodiment, when the flexible printed circuit board 140 is considered to have a front surface on which it is connected to the piezoelectric element 120 and the first end 131 of the terminal member 130, the first electrode 145 and the second electrode 146 are arranged on the front surface.

[0035] When providing the first electrode 145 and the second electrode 146 to the flexible printed circuit board 140, if the first electrode 145 and the second electrode 146 are placed separately on the front and back surfaces of the flexible printed circuit board 140, the manufacturing process for providing the first electrode 145 and the second electrode 146 to the flexible printed circuit board 140 involves multiple steps. This makes the manufacturing process complex and increases manufacturing costs. On the other hand, if the first electrode 145 and the second electrode 146 are placed on either the front or back surface of the flexible printed circuit board 140, the manufacturing process for providing the first electrode 145 and the second electrode 146 to the flexible printed circuit board 140 can be reduced to a single step, thus enabling the flexible printed circuit board 140 to be manufactured at a lower cost.

[0036] The first filler material 150 is filled so as to fill the bottom 111 side of the case 110. The piezoelectric element 120 and a part of the flexible printed circuit board 140 are embedded in the first filler material 150. Specifically, in the flexible printed circuit board 140, the first surface 141 and at least the portion of the second surface 142 closer to the first surface 141 are embedded in the first filler material 150.

[0037] The first filler 150 is made of foamed silicone resin. The first filler 150 is formed by curing liquid silicone resin.

[0038] The first filler material 150 has a height H2 from the outer bottom surface of the bottom portion 111 located on the outer surface of the case 110 to the upper end of the first filler material 150. The ratio of the height H2 of the first filler material 150 to the height H1 of the case 110 in the height direction (DR2 direction) perpendicular to the bottom portion 111 is 0.3 times or more and 0.7 times or less. This ensures that the first end portion 131 of the terminal member 130 is positioned inside the case 110, and suppresses a decrease in the ultrasonic vibration sound absorption characteristics of the first filler material 150.

[0039] The second filler 160 is filled in the case 110 so as to fill the first filler 150. The second filler 160 is made of silicone resin. The second filler 160 may also be made of a resin material such as urethane resin.

[0040] The method for manufacturing the ultrasonic transducer 100 according to Embodiment 1 of the present invention will be described below.

[0041] Figure 2 is a flowchart showing a method for manufacturing an ultrasonic transducer according to Embodiment 1 of the present invention. Figure 3 is a cross-sectional view showing the state in which the piezoelectric element and the flexible printed circuit board of the ultrasonic transducer according to Embodiment 1 of the present invention are connected. Figure 4 is a longitudinal cross-sectional view showing the state in which the piezoelectric element of the ultrasonic transducer according to Embodiment 1 of the present invention is attached to the bottom of the case. Figure 5 is a longitudinal cross-sectional view showing the state in which the first filler material of the ultrasonic transducer according to Embodiment 1 of the present invention is filled inside the case. Figure 6 is a longitudinal cross-sectional view showing the state in which the terminal member of the ultrasonic transducer according to Embodiment 1 of the present invention is connected to the flexible printed circuit board. Figure 7 is a longitudinal cross-sectional view showing the state in which the first end of the terminal member is positioned inside the case by bending the flexible printed circuit board of the ultrasonic transducer according to Embodiment 1 of the present invention.

[0042] As shown in Figures 2 and 3, the manufacturing method for the ultrasonic transducer 100 involves first connecting the first electrode 145 of the flexible printed circuit board 140 to the first main surface 121 of the piezoelectric element 120 (step S1).

[0043] Next, as shown in Figures 2 and 4, the second main surface 122 of the piezoelectric element 120 to which the flexible printed circuit board 140 is connected is attached to the bottom portion 111, and the flexible printed circuit board 140 is brought into contact with the side wall portion 112 and bent while positioning the second electrode 146 on the outside of the case 110 (step S2). As a result, the first surface portion 141 is formed on the flexible printed circuit board 140.

[0044] As the flexible printed circuit board 140 is bent while in contact with the side wall portion 112, the side wall portion 112 can support the flexible printed circuit board 140, thereby suppressing variations in the position of the second electrode 146 of the flexible printed circuit board 140. Specifically, the positional accuracy of the second electrode 146 can be reduced to ±0.2 mm or less relative to the design position. As a result, when the flexible printed circuit board 140 and the terminal member 130 are connected, as described later, variations in their connection positions are suppressed, making it easier to automate the connection between the flexible printed circuit board 140 and the terminal member 130 using automated equipment.

[0045] Next, as shown in Figures 2 and 5, the first filler material 150 is filled into the bottom 111 side of the case 110 to fix a portion of the flexible printed circuit board 140 (step S3).

[0046] The first filler 150 can be formed by potting. In potting, liquid silicone resin is applied to the piezoelectric element 120 and the flexible printed circuit board 140 inside the case 110, and then the liquid silicone resin is cured. This allows the first filler 150 to be attached in close contact with the piezoelectric element 120 and the flexible printed circuit board 140, regardless of their shapes.

[0047] Next, as shown in Figures 2 and 6, the second electrode 146 of the flexible printed circuit board 140 is connected to the first end 131 of the terminal member 130 on the outside of the case 110 (step S4). Since a part of the flexible printed circuit board 140 is fixed by the first filler 150, distortion of the entire flexible printed circuit board 140 is suppressed. Note that if the side of the flexible printed circuit board 140 connected to the piezoelectric element 120 and the first end 131 of the terminal member 130 is considered the front surface, the first end 131 may be connected to the back surface of the flexible printed circuit board 140.

[0048] When connecting the second electrode 146 to the first end 131, a portion of the flexible printed circuit board 140 extends linearly to the outside of the case 110 along the side wall portion 112, so that space is secured around the second electrode 146 without any obstacles being placed therein. When the second electrode 146 and the first end 131 are connected by soldering using automated equipment, interference between the terminal member 130 and the flexible printed circuit board 140 and the components of the automated equipment is suppressed, so that the connection between the second electrode 146 and the first end 131 can be automated.

[0049] Next, as shown in Figures 2 and 7, the second end 132 of the terminal member 130 is positioned outside the case 110, while the first end 131 of the terminal member 130 to which the flexible printed circuit board 140 is connected is positioned inside the case 110, causing the portion of the flexible printed circuit board 140 exposed from the first filler material 150 to bend (step S5).

[0050] The first filler 150 fills in and fixes a portion of the flexible printed circuit board 140, so that the portion of the flexible printed circuit board 140 embedded in the first filler 150 maintains its shape while the portion of the flexible printed circuit board 140 exposed from the first filler 150 is bent. As a result, a second surface portion 142 and a third surface portion 143 are formed on the flexible printed circuit board 140.

[0051] Next, as shown in Figures 1 and 2, the second filler 160 is filled in the case 110 to fill the first filler 150 and the bent portion of the flexible printed circuit board 140 that is exposed from the first filler 150 (step S6). The ultrasonic transducer 100 can be manufactured by the above-described process.

[0052] (Example of experiment) Here, we will describe a first experimental example that verifies the relationship between the ratio of the height H2 of the first filler material 150 to the height H1 of the case 110 and the determination of the quality of the arrangement when the piezoelectric element 120 and the flexible printed circuit board 140 are placed inside the case 110. The experimental conditions were to verify whether the piezoelectric element 120 and the flexible printed circuit board 140 could be placed inside the case 110 without problems when the ratio of the height H2 of the first filler material 150 to the height H1 of the case 110 was changed.

[0053] Table 1 summarizes the relationship between the ratio of the height H2 of the first filler material 150 to the height H1 of the case 110 and the judgment of the quality of the arrangement when the piezoelectric element 120 and the flexible printed circuit board 140 are placed inside the case 110, based on the results of the first experimental example.

[0054] [Table 1]

[0055] As shown in Table 1, when the ratio was between 0.3 and 0.7, the piezoelectric element 120 and the flexible printed circuit board 140 could be placed inside the case 110 without any problems.

[0056] On the other hand, when the ratio was 0.2, although it was possible to fix a portion of the flexible printed circuit board 140 with the first filler 150, the sound absorption characteristics of the first filler 150 deteriorated, and the reverberation vibration became longer. As a result, the short-range detection performance when the ultrasonic transducer 100 is used as an ultrasonic sensor deteriorated.

[0057] Furthermore, if the ratio is 0.8, when bending the flexible printed circuit board 140 and placing it inside the case 110, there will be insufficient space inside the case 110, making it impossible to house the entire flexible printed circuit board 140 inside the case 110. This ratio can be measured, for example, by observing an ultrasonic transducer cut in a longitudinal section using an optical microscope.

[0058] Next, we will describe a second experimental example that verifies the relationship between the curvature R of the boundary between the first surface 141 and the second surface 142 of the flexible printed circuit board 140 and the determination of whether the flexible printed circuit board 140 is properly positioned. The experimental conditions were to verify whether the flexible printed circuit board 140 could be positioned in the case 110 without problems when the curvature R was changed.

[0059] Table 2 summarizes the relationship between the curvature R of the boundary between the first surface 141 and the second surface 142 of the flexible printed circuit board 140 and the judgment of the quality of the arrangement of the flexible printed circuit board 140, based on the results of the second experimental example.

[0060] [Table 2]

[0061] As shown in Table 2, when the curvature R was between 0.8 (1 / mm) and 2.9 (1 / mm), the flexible printed circuit board 140 could be placed inside the case 110 without any problems.

[0062] On the other hand, if the curvature R is 0.7, the flexible printed circuit board 140 will be tilted inside the case 110, making it impossible to position the flexible printed circuit board 140 along the side wall 112. As a result, the position of the flexible printed circuit board 140 inside the case 110 cannot be determined, and the connection between the second electrode 146 and the first end 131 cannot be automated.

[0063] Furthermore, when the curvature R was 5.0, stress concentration occurred on the piezoelectric element 120 from the first surface portion 141 formed by bending the flexible printed circuit board 140. This resulted in poor conductivity between the piezoelectric element 120 and the flexible printed circuit board 140. The curvature R can be measured, for example, by observing an ultrasonic transducer cut in a longitudinal section using an optical microscope.

[0064] In the ultrasonic transducer 100 according to Embodiment 1 of the present invention, the second surface portion 142 of the flexible printed circuit board 140 curves up from the edge adjacent to the side wall portion 112 of the first surface portion 141 and extends along the side wall portion 112 of the case 110. This allows for an increase in the proportion of the first filler material 150 positioned directly above the piezoelectric element 120, thereby allowing the ultrasonic vibrations emitted from the piezoelectric element 120 to be absorbed by the first filler material 150. As a result, the sound absorption characteristics of the first filler material 150 can be fully utilized, thereby improving the acoustic characteristics of the ultrasonic transducer 100.

[0065] In the ultrasonic transducer 100 according to Embodiment 1 of the present invention, the second surface portion 142 is fixed to the first filler material 150 in a state where it extends along the side wall portion 112, thereby suppressing variations in the position of a portion of the flexible printed circuit board 140 near the piezoelectric element 120. Therefore, variations in the position of the first filler material 150 covering a portion of the flexible printed circuit board 140 near the piezoelectric element 120 can be suppressed. As a result, variations in the sound absorption characteristics of the first filler material 150 can be suppressed.

[0066] In the ultrasonic transducer 100 according to Embodiment 1 of the present invention, the second surface portion 142 is in direct contact with the side wall portion 112, which makes it easier to position the flexible printed circuit board 140 within the case 110, thereby suppressing variations in the sound absorption characteristics of the first filler material 150. As a result, variations in the position of the first filler material 150 covering a portion of the flexible printed circuit board 140 near the piezoelectric element 120 can be suppressed.

[0067] In the ultrasonic transducer 100 according to Embodiment 1 of the present invention, by arranging the first electrode 145 and the second electrode 146 on either the front or back surface of the flexible printed circuit board 140, the first electrode 145 and the second electrode 146 can be formed on the flexible printed circuit board 140 in the same manufacturing process. This simplifies the manufacturing process of the flexible printed circuit board 140, allowing the flexible printed circuit board 140 to be manufactured at a low cost.

[0068] In the ultrasonic transducer 100 according to Embodiment 1 of the present invention, by setting the ratio of the height H2 of the first filler material 150 to the height H1 of the case 110 in the height direction (DR2 direction) perpendicular to the bottom 111 to 0.3 times or more and 0.7 times or less, the first end portion 131 can be housed inside the case 110 while maintaining the sound absorption characteristics of the first filler material 150.

[0069] In the ultrasonic transducer 100 according to Embodiment 1 of the present invention, by setting the curvature R of the second surface portion 142 located at the boundary with the edge of the first surface portion 141 of the flexible printed circuit board 140 to 0.8 (1 / mm) or more and 2.9 (1 / mm) or less, it is possible to configure the curvature necessary to make the flexible printed circuit board 140 stand upright in the case 110 while suppressing the overload applied when bending the flexible printed circuit board 140.

[0070] In the manufacturing method of the ultrasonic transducer 100 according to Embodiment 1 of the present invention, a portion of the flexible printed circuit board 140 near the piezoelectric element 120 is fixed by the first filler material 150 so as to extend along the side wall portion 112, and the second electrode 146 is positioned outside the case 110, thereby enabling the connection of the second electrode 146 and the first end portion 131 while securing space around the second electrode 146. This suppresses interference between the terminal member 130 and the flexible printed circuit board 140 with the components of the automated equipment, and thus enables the connection of the second electrode 146 and the first end portion 131 to be automated. Consequently, by automating the connection of the terminal member 130 and the flexible printed circuit board 140, the ultrasonic transducer 100 can be manufactured efficiently.

[0071] (Embodiment 2) The ultrasonic transducer according to Embodiment 2 of the present invention will now be described with reference to the figures. Since the configuration of the terminal members of the ultrasonic transducer according to Embodiment 2 of the present invention differs from that of the ultrasonic transducer 100 according to Embodiment 1 of the present invention, the same configuration as that of the ultrasonic transducer 100 according to Embodiment 1 of the present invention will not be repeated in the description.

[0072] Figure 8 is a longitudinal cross-sectional view of an ultrasonic transducer according to Embodiment 2 of the present invention. As shown in Figure 8, the ultrasonic transducer 200 according to Embodiment 2 of the present invention comprises a bottomed cylindrical case 110, a piezoelectric element 120, a terminal member 230, a strip-shaped flexible printed circuit board 240, a first filler material 150, and a second filler material 160. In this embodiment, the terminal member 230 is a lead terminal.

[0073] The flexible printed circuit board 240 includes a first surface 241, a second surface 242, and a third surface 243.

[0074] The third surface portion 243 has a second electrode 246 that is electrically connected to the terminal member 230. The second electrode 246 is connected, for example, by soldering to the terminal member 230.

[0075] In the ultrasonic transducer 200 according to Embodiment 2 of the present invention, the second surface portion 242 of the flexible printed circuit board 240 curves up from the edge adjacent to the side wall portion 112 of the first surface portion 241 and extends along the side wall portion 112 of the case 110. This allows for an increase in the proportion of the first filler material 150 directly above the piezoelectric element 120, thereby allowing the ultrasonic vibrations emitted from the piezoelectric element 120 to be absorbed by the first filler material 150. As a result, the sound absorption characteristics of the first filler material 150 can be fully demonstrated.

[0076] In the ultrasonic transducer 200 according to Embodiment 2 of the present invention, the terminal member 230 being a lead terminal improves the degree of freedom to bend the third surface portion 243 of the flexible printed circuit board 240 compared to the case where the terminal member is a pin terminal.

[0077] [Note] <1> A bottomed cylindrical case having a bottom and side walls, A piezoelectric element having a first main surface and a second main surface, wherein the second main surface is attached to the bottom of the case on the inside, A terminal member having a first end positioned inside the case and a second end positioned outside the case, A strip-shaped flexible printed circuit board electrically connects the piezoelectric element and the first end of the terminal member, A first filling material is filled to fill the bottom of the case, The case comprises a second filler material filled so as to fill the first filler material inside the case, The aforementioned flexible printed circuit board is Having a first electrode electrically connected to the piezoelectric element, and a first surface portion extending while in contact with the first main surface of the piezoelectric element, A second surface portion curves upward from the edge of the first surface portion adjacent to the side wall portion and extends along the side wall portion of the case, The terminal member has a second electrode electrically connected to the first end, and includes a third surface portion that is bent in an S-shape from the upper end of the second surface portion and faces the first surface portion at a distance from it, An ultrasonic transducer in which the first surface and at least the portion of the second surface closest to the first surface are embedded in the first filler.

[0078] <2> The second surface portion is in direct contact with the side wall portion. <1> The ultrasonic transducer described above.

[0079] <3> The first electrode and the second electrode are arranged on either the front or back surface of the flexible printed circuit board. <1> or <2> The ultrasonic transducer described above.

[0080] <4> The ratio of the height of the first filler material to the height of the case in the height direction perpendicular to the bottom is 0.3 times or more and 0.7 times or less. <1> from <3> An ultrasonic transducer as described in any one of the following.

[0081] <5> The curvature of the second surface portion of the flexible printed circuit board at the boundary with the edge of the first surface portion is 0.8 (1 / mm) or more and 2.9 (1 / mm) or less. <1> from <4> An ultrasonic transducer as described in any one of the following.

[0082] <6> A piezoelectric element having a first main surface and a second main surface, A bottomed cylindrical case having a bottom and side walls, A terminal member having a first end and a second end, A strip-shaped flexible printed circuit board having a first electrode and a second electrode, electrically connecting the piezoelectric element and the terminal member to each other, The first filling material is filled into the aforementioned case, A method for manufacturing an ultrasonic transducer comprising a second filling material filled inside the case, A step of connecting the first electrode of the flexible printed circuit board to the first main surface of the piezoelectric element, The steps include: attaching the second main surface of the piezoelectric element to which the flexible printed circuit board is connected to the bottom, and positioning the second electrode on the outside of the case while bending the flexible printed circuit board in contact with the side wall; A step of filling the bottom of the case with the first filler material to fix a part of the flexible printed circuit board, The process of connecting the second electrode of the flexible printed circuit board to the first end of the terminal member on the outside of the case, A step of bending the portion of the flexible printed circuit board that is exposed from the first filler, by positioning the second end of the terminal member on the outside of the case and the first end of the terminal member to which the flexible printed circuit board is connected on the inside of the case, A method for manufacturing an ultrasonic transducer, comprising the steps of filling the case with a first filler and a second filler so as to fill the portion of the flexible printed circuit board that is exposed from the first filler and bent.

[0083] In the description of the embodiments described above, the combinable configurations may be combined with each other.

[0084] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended. [Explanation of symbols]

[0085] 100,200 Ultrasonic transducer, 110 Case, 111 Bottom, 112 Side wall, 120 Piezoelectric element, 121 First main surface, 122 Second main surface, 130,230 Terminal members, 131 First end, 132 Second end, 133 Support member, 140,240 Flexible printed circuit board, 141,241 First surface, 142,242 Second surface, 143,243 Third surface, 145 First electrode, 146,246 Second electrode, 150 First filler, 160 Second filler, H1,H2 Height, R Curvature.

Claims

1. A bottomed cylindrical case having a bottom and side walls, A piezoelectric element having a first main surface and a second main surface, wherein the second main surface is attached to the bottom of the case on the inside, A terminal member having a first end positioned inside the case and a second end positioned outside the case, A strip-shaped flexible printed circuit board electrically connects the piezoelectric element and the first end of the terminal member, A first filler material is filled to fill the bottom of the case, The case comprises a second filler material filled so as to fill the first filler material inside the case, The aforementioned flexible printed circuit board is Having a first electrode electrically connected to the piezoelectric element, and a first surface portion extending while in contact with the first main surface of the piezoelectric element, A second surface portion curves upward from the edge of the first surface portion adjacent to the side wall portion and extends along the side wall portion of the case, The terminal member has a second electrode electrically connected to the first end, and includes a third surface portion that is bent in an S-shape from the upper end of the second surface portion and faces the first surface portion at a distance from it, The first surface and at least the portion of the second surface closest to the first surface are embedded in the first filler. The third surface is embedded in the second filler, An ultrasonic transducer in which the ratio of the height of the first filler to the height of the case in the height direction perpendicular to the bottom is 0.3 times or more and 0.7 times or less.

2. The ultrasonic transducer according to claim 1, wherein the second surface portion is in direct contact with the side wall portion.

3. The ultrasonic transducer according to claim 1 or claim 2, wherein the first electrode and the second electrode are arranged on either the front surface or the back surface of the flexible printed circuit board.

4. The ultrasonic transducer according to claim 1, wherein the curvature of the second surface portion located at the boundary with the edge of the first surface portion of the flexible printed circuit board is 0.8 (1 / mm) or more and 2.9 (1 / mm) or less.

5. A piezoelectric element having a first main surface and a second main surface, A bottomed cylindrical case having a bottom and side walls, A terminal member having a first end and a second end, A strip-shaped flexible printed circuit board having a first electrode and a second electrode, electrically connecting the piezoelectric element and the terminal member to each other, The first filling material is filled inside the case, A method for manufacturing an ultrasonic transducer comprising a second filler material filled inside the case, A step of connecting the first electrode of the flexible printed circuit board to the first main surface of the piezoelectric element, The steps include: attaching the second main surface of the piezoelectric element to which the flexible printed circuit board is connected to the bottom, and positioning the second electrode on the outside of the case while bending the flexible printed circuit board in contact with the side wall; A step of filling the bottom of the case with the first filler material to fix a part of the flexible printed circuit board, The process of connecting the second electrode of the flexible printed circuit board to the first end of the terminal member on the outside of the case, A step of bending the portion of the flexible printed circuit board that is exposed from the first filler, with the second end of the terminal member positioned outside the case and the first end of the terminal member to which the flexible printed circuit board is connected positioned inside the case, The process includes filling the case with the first filler and filling the flexible printed circuit board with the second filler so as to fill the portion of the flexible printed circuit board that is exposed from the first filler and bent, A method for manufacturing an ultrasonic transducer, comprising the step of filling the flexible printed circuit board with the first filler to fix the part of the flexible printed circuit board, wherein the part of the flexible printed circuit board is filled with the first filler.

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