Patent Application
20220105542
The present disclosure relates to an ultrasonic transducer.
Conventionally, an ultrasonic transducer in which a piezoelectric vibrator is disposed in a case is known. For example, Japanese Patent No. 4182156 discloses an ultrasonic transducer having a plate-shaped piezoelectric vibrator with electrodes formed on both main surfaces thereof, and a wire for inputting signals to the electrodes of the piezoelectric vibrator.
In an ultrasonic transducer, further reduction of reverberation of an ultrasonic component is required. However, in the above-described conventional ultrasonic transducer, reverberation of the ultrasonic component is not sufficiently reduced.
An advantage of some aspects of the present disclosure is to provide an ultrasonic transducer in which reverberation of an ultrasonic component is reduced.
According to an embodiment of the present disclosure, there is provided an ultrasonic transducer including a case, a piezoelectric vibrator with a plate shape disposed in the case, a wiring member which is overlapped with the piezoelectric vibrator in the case and inputs a signal for vibrating the piezoelectric vibrator received from the outside to the piezoelectric vibrator, and a damper portion which is provided in the wiring member and is adjacent to the piezoelectric vibrator when viewed from a thickness direction of the piezoelectric vibrator.
In the ultrasonic transducer above, the damper portion provided adjacent to the piezoelectric vibrator prevents vibration transmitted through the wiring member due to vibration of the piezoelectric vibrator. Therefore, the ultrasonic transducer can reduce reverberation of the ultrasonic component.
An ultrasonic transducer according to another aspect includes an external wiring that inputs a signal for vibrating a piezoelectric vibrator to a wiring member.
In the ultrasonic transducer according to another aspect, the external wiring extends in a direction along the thickness direction of the piezoelectric vibrator.
In the ultrasonic transducer according to another aspect, the wiring member has a contact portion that is in contact with the external wiring outside the damper portion when viewed from the thickness direction of the piezoelectric vibrator.
In the ultrasonic transducer according to another aspect, the damper portion is positioned between the contact portion and the piezoelectric vibrator when viewed from the thickness direction of the piezoelectric vibrator.
In the ultrasonic transducer according to another aspect, the damper portion extends across between the contact portion and the piezoelectric vibrator when viewed from the thickness direction of the piezoelectric vibrator.
In the ultrasonic transducer according to another aspect, the damper portion is thinner than the contact portion of the wiring member.
In the ultrasonic transducer according to another aspect, the area of the formation region of the damper portion in the wiring member is larger than the contact area between the wiring member and the external wiring and is larger than the contact area between the wiring member and the piezoelectric vibrator.
In the ultrasonic transducer according to another aspect, the damper portion is bent in the thickness direction of the piezoelectric vibrator.
In the ultrasonic transducer according to another aspect, an opening is provided in the wiring member, and an edge portion of the opening is in contact with the piezoelectric vibrator.
Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same element or the element having the same function is denoted by the same reference numeral, and redundant description is omitted.
The structure of the ultrasonic transducer 1 according to the present embodiment will be described with reference to
The ultrasonic transducer 1 is configured to be capable of transmitting and receiving ultrasonic waves. The ultrasonic transducers 1 includes a case 10 defining a housing space 51, a piezoelectric vibrator 20 housed in the housing space S1 of the case 10, a wiring member 30, a pair of first pins 41 and 43, a plurality of sleeves 46 and 47, a sound absorbing material 50 and a substrate 60, a pair of second pins 65 and 67, and a vibration isolator 70.
The case 10 is a bottomed cylindrical member having an opening at one end, and includes a bottom wall 11 and a side wall 13 that define the housing space S1. The side wall 13 extends in a direction intersecting the bottom wall 11, and the side wall 13 may extend in a direction orthogonal to the bottom wall 11. In the present embodiment, the bottom wall 11 and the side wall 13 are integrally formed and made of the same material. The case 10 is made of, for example, aluminum (Al). The case 10 may be made of a metal other than Al. The case 10 may be made of, for example, an aluminum alloy, stainless steel, or a copper alloy. The aluminum alloy includes duralumin, for example. The copper alloy includes brass, for example.
The bottom wall 11 of the case 10 has a bottom surface 12 facing the housing space S1 side. The bottom surface 12 has a circular shape having a long diameter and a short diameter when viewed from a direction intersecting the bottom surface 12. In the present embodiment, the bottom surface 12 has an elliptical shape. In the bottom surface 12, the direction along the long diameter and the direction along the short diameter intersect each other. For example, the direction along the long diameter and the direction along the short diameter are orthogonal to each other. The thickness of the bottom wall 11 is, for example, not less than 0.7 mm and not more than 1.5 mm. In the present embodiment, the thickness of the bottom wall 11 is 0.9 mm.
Hereinafter, a direction along the long diameter of the bottom surface 12 is defined as an X direction, a direction along the short diameter of the bottom surface 12 is defined as a Y direction, and a direction orthogonal to the bottom surface 12 is defined as a Z direction.
The bottom surface 12 is defined by a pair of edges 12a with a linear shape and a pair of edges 12b with an arc shape. The pair of edges 12a extend in the X direction and are separated from each other in the Y direction. The pair of edges 12a are substantially parallel to each other. The edges 12b connect ends of the edges 12a. The circular shape having the long diameter and the short diameter may be an oval shape. The direction intersecting bottom surface 12 may be, for example, a direction orthogonal to bottom surface 12. The direction intersecting the bottom surface 12 may coincide with the direction intersecting the bottom wall 11.
The side wall 13 has an inner side surface 14. The bottom surface 12 and the inner side surface 14 constitute an inner surface of the case 10. A plurality of stepped portions 15 are formed on the inner side surface 14. In the present embodiment, three step portions 15 are formed. One of the step portions 15 extends along one edge 12a. The other two of the step portions 15 are provided apart from each other along the other edge 12a. The step portions 15 are used for positioning the vibration isolator 70 with respect to the case 10.
As shown in
The piezoelectric element body 21 has a cuboid shape and a square shape in plan view. The “cuboid shape” in this specification includes a cuboid shape in which corner portions and ridge portions are chamfered and a cuboid shape in which corner portions and ridge portions are rounded. The piezoelectric element body 21 has a pair of square main surfaces 21a and 21b facing each other and a pair of side surfaces 21c and 21d facing each other. The side surfaces 21c and 21d extend in a direction (Z direction) in which the pair of main surfaces 21a and 21b face each other so as to connect the pair of main surfaces 21a and 21b. The main surface 21b faces the bottom surface 12. The piezoelectric vibrator 20 is disposed on the bottom wall 11 so that the main surface 21b and the bottom surface 12 face each other. The direction in which the pair of main surfaces 21a and 21b face each other is a direction intersecting the bottom wall 11 (the bottom surface 12). The direction in which the pair of main surfaces 21a and 21b face each other may be a direction orthogonal to the bottom wall 11 (the bottom surface 12).
The piezoelectric element body 21 is made of a piezoelectric ceramic material. The piezoelectric ceramic material may be, for example, PZT [Pb (Zr, Ti) O3], PT (PbTiO3), PLZT [(Pb, La) (Zr, Ti)O3] or barium titanate (BaTiO3). The piezoelectric element body 21 is formed of, for example, a sintered body of a ceramic green sheet containing the above-described piezoelectric ceramic material. The thickness of the piezoelectric element body 21 is, for example, 150 to 500 μm. In the present embodiment, the thickness of the piezoelectric element body 21 is 200 μm.
As shown in
The one electrode 23 covers substantially the entire area of the main surface 21b and continuously covers the side surface 21c and a part of the main surface 21a on the side of the side surface 21c. A portion of the electrode 23 covering the main surface 21b is joined to the bottom wall 11 (the bottom surface 12). The other electrode 25 covers substantially the entire main surface 21a. The electrode 25 is separated from the electrode 23 covering the main surface 21a, and is insulated from the electrode 23. As described above, the piezoelectric element body 21 has a region sandwiched between the pair of electrodes 23 and 25 in the Z direction, and this region constitutes a piezoelectrically active region.
The electrodes 23 and 25 are in direct contact with each of the surfaces 21a to 21c of the piezoelectric body 21. The thickness of each electrode 23 and 25 is 1.5 μm or less. Each of the electrodes 23 and 25 includes, for example, a stack formed of a chromium (Cr) layer, a nickel-copper alloy (Ni—Cu) layer, and a gold (Au) layer. Each of the electrodes 23 and 25 may include silver (Ag), titanium (Ti), platinum (Pt), a silver-palladium alloy (Ag—Pd), or a nickel-chromium alloy (Ni—Cr). The electrodes 23 are 25 and are formed on the surface of the piezoelectric element body 21 by, for example, a sputtering method.
The wiring member 30 is disposed so as to overlap the piezoelectric vibrator 20 in the housing space S1. The wiring member 30 has a sheet shape and has substantially the same shape as the bottom surface 12 in plan view. More specifically, the wiring member 30 is designed to be slightly smaller than the bottom surface 12 in plan view, and is disposed away from the inner side surface 14 of the case 10. The wiring member 30 is, for example, a flexible printed circuit substrate (FPC substrate) or a flexible flat cable (FFC). That is, the wiring member 30 includes a plurality of wires. The wiring member 30 electrically connects the first pins 41 and 43 and the piezoelectric vibrator 20 by a plurality of wires. In the present embodiment, the wiring member 30 has a configuration in which the pair of wirings 31 and 32 are provided in a resin sheet made of resin such as polyimide resin.
As shown in
The base portion 33 is a flat plate portion located at the center of the wiring member 30, and has a pair of main surfaces 33a and 33b facing each other in the Z direction. The wiring member 30 is disposed in the housing space S1 such that the main surface 33b of the base portion 33 faces the piezoelectric element body 21.
A opening 33c with a rectangular shape is provided in a central region of the base portion 33, and the piezoelectric vibrator 20 is partially exposed from the opening 33c. The opening 33c may be provided so that the wiring member 30 does not encumber the vibration of the piezoelectric vibrator 20. The wiring member 30 overlaps the electrodes 23 and 25 of the piezoelectric vibrator 20 at an edge 33d of the opening 33c extending along the Y direction.
The contact portions 34 and 35 extend continuously from the base portion 33 and are provided at positions sandwiching the base portion 33 in the X direction. Each of the contact portions 34 and 35 has an elongated flat plate shape extending in the Y direction, and is designed to be thicker toward the main surface 33b side than the thickness of the base portion 33. One contact portion 34 is located on the side surface 21c side of the piezoelectric element body 21, and the other contact portion 35 is located on the side surface 21d side of the piezoelectric element body 21. The piezoelectric vibrator 20 is not interposed between the contact portions 34 and 35 and the bottom wall 11, and the contact portions 34 and 35 are in direct contact with the bottom surface 12.
The pair of wires 31 and 32 are disposed to extend from the edge 33d of the opening 33c of the base portion 33 overlapping the piezoelectric vibrator 20 to the contact portions 34 and 35. The pair of wires 31 and 32 have first end portions 31a and 32a and second end portions 31b and 32b. The first end portion 31a of the wire 31 is provided over the entire width of the edge 33d of the opening 33c of the base portion 33 overlapping the electrode 23 of the piezoelectric vibrator 20, and is exposed from the resin sheet at the lower surface (the main surface 33b) of the edge 33d to be electrically connected to the electrode 23 of the piezoelectric vibrator 20. The second end portion 31b of the wire 31 is located in the contact portion 34, is exposed from the resin sheet on the second of the contact portion 34, and is electrically connected to the first pin 41 described later. The first end portion 32a of the wire 32 is provided over the entire width of the edge 33d of the opening 33c of the base portion 33 overlapping the electrode 25 of the piezoelectric vibrator 20, is exposed from the resin sheet at the lower surface (the main surface 33b) of the edge 33d, and is electrically connected to the electrode 25 of the piezoelectric vibrator 20. The second end portion 32b of the wire 32 is located in the contact portion 35, is exposed from the resin sheet on the second of the contact portion 35, and is electrically connected to the first pin 43 described later.
The wiring member 30 is further provided with a pair of damper portions 37 and 39 adjacent to the piezoelectric vibrator 20. The damper portions 37 and 39 are provided on the main surface 33b of the base portion 33 of the wiring member 30 and interposed between the wiring member 30 and the bottom wall 11. The damper portions 37 and 39 are provided on the main surface 33b between the piezoelectric vibrator 20 and the contact portions 34 and 35, respectively. One damper portion 37 is provided between the piezoelectric vibrator 20 and the contact portion 34, and the other damper portion 39 is provided between the piezoelectric vibrator 20 and the contact portion 35. In other words, when viewed from the Z direction, the contact portions 34 and 35 of the wiring member 30 are located outside the damper portions 37 and 39. Each of the damper portions 37 and 39 is made of an insulating material, for example, an insulating resin. In the present embodiment, each of the damper portions 37 and 39 is formed of a thermo-compression resin film (for example, a nitrile rubber-based resin film), and in this case, each of the damper portions 37 and 39 is formed by compression in a state in which a surface layer portion is heated and melted. In the present embodiment, the damper portions 37 and 39 are bonded to both the main surface 30b of the wiring member 30 and the bottom surface 12 of the bottom wall 11, thereby fixing the wiring member 30 to the bottom wall 11.
As shown in
The pair of first pins 41,43 (the external wiring) are conductive members having a substantially quadrangular prism shape and extend along the Z direction. The first pins 41 and 43 are aligned so as to be connected to each of the second end portions 31b and 32b of the wires 31 and 32 of the wiring member 30. The first pins 41 and 43 are connected to the end portions 31b and 32b by solder or a conductive adhesive. The first pins 41 and 43 are made of, for example, metal. The first pins 41 and 43 are made of, for example, brass. A plating layer (not shown) may be formed on the surface of each of the first pins 41 and 43. The plating layer may be formed by, for example, nickel plating and tin plating. In this case, the plating layer has a two-layer structure.
Portions on the wiring member 30 side of the pair of first pins 41 and 43 are held by the sleeves 45 and 47, respectively. Each of the sleeve 45 and 47 is a cylindrical member having a flange at the both ends. In the present embodiment, the sleeves 45 and 47 have the same shape. Each of the sleeves 45 and 47 is made of resin. Each of the sleeves 45 and 47 is made of a metal such as, for example, phosphorus deoxidized copper (PDC) or brass. When the sleeves 45 and 47 are made of a metal, not only the first pins 41 and 43 but also the sleeve 45 and 47 can be joined to the conductor layer of the wiring member 30, so that the connection reliability is increased. Each of the sleeves 45 and 47 may be made of PEEK (polyetheretherketone) resin, polybutylene terephthalate resin (PBT resin), or polyphenylene sulfide (PPS) resin.
The flange on one end side of each of the sleeves 45 and 47 is joined to the wiring member 30. The sleeves 45 and 47 are disposed at positions overlapping the contact portions 34 and 35 when viewed from the axial direction (Z direction). The axial length of each of the sleeves 45 and 47 is shorter than the axial length of each of the first pins 41 and 43.
The sound absorbing material 50 is disposed on the piezoelectric vibrator 20. The sound absorbing material 50 is disposed between the pair of first pins 41 and 43. The sound absorbing material 50 is disposed in the housing space S1. The sound absorbing material 50 has, for example, a rectangular parallelepiped shape. As shown in
The substrate 60 is disposed in parallel to the piezoelectric vibrator 20 with the sound absorbing material 50 interposed therebetween. The substrate 60 is disposed in the housing space S1. The substrate 60 is a plate-shaped member. The substrate 60 has a pair of main surfaces 60a and 60b facing each other in the Z direction. The main surface 60b faces the sound absorbing material 50.
Each of the main surfaces 60a and 60b has an ellipse shape. The long diameter direction of each of the main surfaces 60a and 60b is along the Y direction. The short diameter direction of each of the main surfaces 60a and 60b is along the X direction. The pair of the edges in the short diameter direction of each of the main surfaces 60a and 60b are curved so as to expand outward and has an arc shape. The substrate 60 is provided with insertion holes 61 and 63 through which the first pins 41 and 43 are inserted. The insertion holes 61 and 63 are formed at both end portions of the substrate 60 in the X direction and have a circular shape. The pair of the edges in the short diameter direction of each of the main surfaces 60a and 60b is curved along the insertion holes 61 and 63.
The substrate 60 is electrically connected to the pair of first pins 41 and 43. The substrate 60 is made of, for example, glass epoxy substrate. A plurality of conductor layers are disposed in the substrate 60. The plurality of conductor layers are adhered to the substrate 60. In the present embodiment, as shown in
The first pin 41 and the second pin 65 are connected to one conductor layer 66 of the substrate 60 by solder or a conductive adhesive, and are electrically connected to each other through the conductor layer 66. The first pin 43 and the second pin 67 are connected to the other conductor layer 68 of the substrate 60 by solder or a conductive adhesive, and are electrically connected to each other through the conductor layer 68.
The second pins 65 and 67 are disposed on the main surface 60a in a state of being separated from each other in the X direction. The second pins 65 and 67 extend from the main surface 60a in the Z direction and penetrates the vibration isolator 70. The second pins 65 and 67 are disposed between the first pins 41 and 43 in the X direction. In the present embodiment, the second pins 65 and 67 have the same shape. The second pins 65 and 67 are made of, for example, metal. For example, the second pins 65 and 67 are made of brass. A plating layer (not shown) may be formed on the surface of each of the second pins 65 and 67. The plating layer may be formed by, for example, nickel plating and tin plating. In this case, the plating layer has a two-layer structure.
The vibration isolator 70 is disposed in contact with the inner surface (the inner side surface 14) of the case 10 to prevent vibration of the case 10. The vibration isolator 70 is disposed around the sound absorbing material 50. The vibration isolator 70 includes a lid body 71 and a frame 73. The lid body 71 seals the opening of the case 10 in a state where the piezoelectric vibrator 20, the wiring member 30, the first pins 41 and 43, the sleeves 45 and 47, the sound absorbing material 50, and the substrate 60 are disposed in the case 10. The lid body 71 seals the housing space S1. The leading ends of the second pins 65 and 67 protrude from the lid body 71.
A recessed portion 71c in which the first pin 41 is disposed and a recessed portion 71d in which the first pin 43 is disposed are provided on the bottom surface of the recessed portion 71b. The recessed portions 71c and 71d have, for example, a circular cross section. The diameters of the recessed portions 71c and 71d are larger than the diameter of the first pins 41 and 43. The inner surfaces of the recessed portions 71c and 71d are separated from the first pins 41 and 43. The recessed portions 71c and 71d are provided at both the end portions of the bottom surface of the recessed portion 71b in the X direction.
The frame body 73 extends in a direction intersecting the lid body 71. The direction intersecting the lid body 71 may be, for example, a direction orthogonal to the lid body 71. The lid 71 body and the frame body 73 are formed integrally. The vibration isolator 70 is a tubular member having one axial end closed and the other axial end open. The vibration isolator 70 is fitted into the case 10. The vibration isolator 70 is press-fitted into the case 10. The frame body 73 extends from the lid body 71 to the inside of the case 10 along the Z direction. The frame body 73 is separated from the bottom surface 12. The frame body 73 is in contact with the inner side surface 14 of the case 10.
The frame body 73 surrounds the sound absorbing material 50. The sound absorbing material 50 protrudes to the piezoelectric vibrator 20 side more than the vibration isolator 70 (frame body 73) in the thickness direction (Z direction) of the piezoelectric vibrator 20. The distance between the frame body 73 and the piezoelectric vibrator 20 in the Z direction is longer than the distance between the sound absorbing material 50 and the piezoelectric vibrator 20 in the Z direction.
The frame body 73 has a pair of side portions 75 and a pair of side portions 77. The pair of side portions 75 face each other in the X direction with the sound absorbing material 50 interposed therebetween. The pair of side portions 77 face each other in the Y direction with the sound absorbing material 50 interposed therebetween. The side portions 75 face the side surfaces 50c of the sound absorbing material 50. Each of the side portions 75 is spaced from the sound absorbing material 50.
The pair of side portions 77 sandwich and hold the sound absorbing material 50. The sound absorbing material 50 is fitted between the pair of side portions 77. The pair of side portions 77 compress the sound absorbing material 50. The sound absorbing material 50 presses the pair of side portions 77 by a repulsive force against the compression. Each of the side portions 77 is in contact with each of the side surfaces 50d of the sound absorbing material 50.
The vibration isolator 70 further includes a plurality of protruding portions 79 protruding from the lid body 71 toward the inner side surface 14. The protruding portion 79 is provided in the lid body 71 at a position corresponding to the step portion 15 of the case 10. The protruding portion 79 is disposed in the corresponding step portion 15. The vibration isolator 70 is positioned with respect to the case 10 by the protruding portion 79 being locked to the step portion 15.
The vibration isolator 70 is an elastic body and prevents reverberation by elasticity. The vibration isolator 70 is made of resin. The vibration isolator 70 is a non-foamed body and has a density higher than that of the sound absorbing material 50. The vibration isolator 70 is made of, for example, silicone rubber. The vibration isolator 70 is made of, for example, RTV (Room Temperature Vulcanizing) silicone rubber.
The ultrasonic transducer 1 described above transmits an output wave and receives the output wave reflected from the inspection target. When the ultrasonic sensor is close to the inspection target and the distance from the ultrasonic transducer 1 to the inspection target is small, the voltage of the reverberation component generated in transmitting the output wave interferes with the reception voltage of the output wave reflected from the inspection target. This may make it difficult for the ultrasonic transducer 1 to detect the reception voltage.
The ultrasonic transducer 1 includes the case 10, the piezoelectric vibrator 20 disposed in the case 10, the wiring member 30 overlapped with the piezoelectric vibrator 20 in the case 10 and inputting a signal for vibrating the piezoelectric vibrator 20 received from the outside to the piezoelectric vibrator 20, and the damper portions 37 and 39 provided in the wiring member 30 and adjacent to the piezoelectric vibrator 20 when viewed from the thickness direction (Z direction) of the piezoelectric vibrator 20. In the ultrasonic transducer 1, the damper portions 37 and 39 provided adjacent to the piezoelectric vibrator 20 prevent vibration transmitted through the wiring member 30 due to vibration of the piezoelectric vibrator 20. The damper portions 37 and 39 can prevent longitudinal vibration (vibration in the Z direction) and lateral vibration (vibration in the X direction). The prevention of vibration by the damper portions 37 and 39 allows the ultrasonic transducer 1 to reduce reverberation of the ultrasonic component.
The damper portions 37 and 39 are separated from the piezoelectric vibrator 20 by a predetermined distance so as not to be in contact with the piezoelectric vibrator 20, thereby preventing the damper portions 37 and 39 from encumbering the vibration of the piezoelectric vibrator 20. In addition, the damper portions 37 and 39 can be separated from the contact portions 34 and 35 by a predetermined distance so as not to come into contact with the contact portions 34 and 35 of the wiring member 30. In this case, the vibration of the piezoelectric vibrator 20 is prevented from directly propagating from the damper portions 37 and 39 to the contact portions 34 and 35, and the reverberation of the ultrasonic wave component is further reduced.
The thickness d1 of each of the damper portions 37 and 39 may be equal to the separation distance d2 between the base portion 33 and the bottom wall 11 or may be smaller than the separation distance d2. When the thickness d1 is smaller than the separation distance d2, the damper portions 37 and 39 and the base portion 33 of the wiring member 30 are bent in the Z direction.
Although the embodiments of the present disclosure have been described above, the present disclosure is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.
For example, the ultrasonic transducer 1 may transmit only ultrasonic waves. The piezoelectric vibrator 20 may include one or more internal electrodes disposed in the piezoelectric element body 21. In this case, the piezoelectric element body 21 may have a plurality of piezoelectric layers, and the internal electrodes and the piezoelectric layers may be alternately arranged.
Furthermore, the piezoelectric element body 21 may have a rectangular shape or a circular shape instead of a square shape when viewed from the Z direction. In addition, the opening 30c of the wiring member 30 is not limited to a quadrangular shape, and may be a U-shape.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-166938 | Oct 2020 | JP | national |
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-166938, filed on 1 Oct. 2020, the entire contents of which are incorporated herein by reference.
