JP2011077917A - Ultrasonic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the position accuracy of a fixing plate to a case, and to prevent a wobble from being easily generated between the case and a fixing plate in an ultrasonic transducer. <P>SOLUTION: The ultrasonic transducer 10 includes the case 1, the fixing member 3, and a piezoelectric body 2. The case 1 has a bottomed cylindrical shape where an edge in a spindle direction is blocked. The piezoelectric body 2 is stored in the case 1 while being joined to the bottom face of the case 1 from a direction opposite to the spindle direction. The fixing member 3 is stored in the case 1 while the fixing member 3 abuts on the case 1 at three points from a direction opposite to the spindle direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrasonic transducer that transmits or receives ultrasonic waves by driving a piezoelectric body.

  As a conventional ultrasonic transducer, a piezoelectric body, a sound absorbing member, an elastic material, etc. are inserted into the case, a metal pin as an external connection terminal is fixed to the fixing plate, and the fixing plate is in contact with the elastic material in the case. Some are fixed (for example, refer to Patent Document 1). In addition, there is a type that positions a fixed plate by bringing a fixed plate into contact with a step provided inside the case.

FIG. 1 is a cross-sectional view illustrating a configuration example of a conventional ultrasonic transducer.
The ultrasonic transducer 100 includes a case 101, a piezoelectric body 102, a fixing plate 103, a filler 104, and a metal pin 105.

  The piezoelectric body 102 is bonded to the inner bottom surface of the case 101 with an adhesive (not shown). The case 101 has a bottomed cylindrical shape. A fixing plate 103 for fixing the external connection terminal metal pin 105 for transmitting an electric signal to the outside is inserted into the cylinder of the case 101, and positioned in contact with the step portion 101A having a partially small inner diameter. . The filler 104 is filled in a space outside the fixing plate 103 of the case 101 and fixes the fixing plate 103 to the case 101.

JP-A 63-134976

  In the ultrasonic transducer, multiple reflections of sound waves occur in the inner space between the inner bottom surface of the case and the fixed plate. The sound wave attenuates due to the multiple reflection, but if the reverberation time of the sound wave is long, the waveform of the transmission wave of the ultrasonic transducer becomes dull due to the reverberation, or the received wave is hidden by the reverberation. The reverberation characteristics of ultrasonic transducers are greatly influenced by the shape of the inner space, and in order to stabilize the reverberation characteristics, it is required to set the distance and parallelism between the inner bottom surface of the case and the fixed plate with high accuracy. The In addition, high positional accuracy is required for the external connection terminals and the fixing plate from the viewpoint of the mountability of the external connection terminals to the set substrate.

  In the above-described conventional configuration, the fixing plate comes into contact with the entire step portion provided along the inner periphery of the case, and the fixing plate is positioned. For this reason, a slight deviation in flatness at the contact surfaces of the stepped portion and the fixed plate reduces the positional accuracy of the fixed plate with respect to the case, and rattling is likely to occur between the case and the fixed plate portion. This will affect the reverberation characteristics.

  An object of the present invention is to provide an ultrasonic transducer in which the positional accuracy of the fixing plate with respect to the case is high and rattling is unlikely to occur between the case and the fixing plate portion.

The ultrasonic transducer according to the present invention includes a case, a fixing member, and a piezoelectric body. The case has a bottomed cylindrical shape with the end in the main axis direction closed. The piezoelectric body is formed on the inner bottom surface of the case. The fixing member is disposed away from the inner bottom surface portion of the case, and is accommodated in the case in contact with the case at three points from the opposite direction of the main axis direction.
In this configuration, since the fixing member is supported at three points, the positional accuracy of the fixing plate with respect to the case can be increased by increasing the shape accuracy of the contact portion without increasing the flatness of the entire contact surface as in the prior art. . When molding a fixing member or a case by resin molding or the like, it is easier to increase the shape accuracy of the contact portion than to increase the flatness of the contact surface. Further, the three contact positions of the fixing member with the case are not shifted as in the case of surface contact, and rattling of the fixing member in the case can be suppressed.

The case of the present invention includes a holding portion for holding a fixing member, and the fixing member includes a locking claw provided with a return portion at a tip on a main surface in the main axis direction, and the holding portion is provided in a direction opposite to the main axis direction. It is preferable that the return portion comes into contact with the holding portion from the main axis direction while making contact.
In this configuration, the locking claw can restrict the lifting of the fixing member in the direction opposite to the main shaft direction, can further increase the positional accuracy of the fixing member, and can suppress rattling of the fixing member in the case.

The ultrasonic transducer according to the present invention preferably includes a sound absorbing member accommodated in the case, and the fixing member preferably includes a receiving portion that supports the sound absorbing member.
In this configuration, the sound absorbing member suppresses reverberation in the cavity inside the case, and the positional accuracy of the sound absorbing member also affects the reverberation characteristics. Therefore, by positioning the sound absorbing member with the fixing member having high position accuracy, the position accuracy of the sound absorbing member is increased and the stability of the reverberation characteristic can be enhanced.

  According to this invention, since the fixing member is supported at three points, the positional accuracy of the fixing plate with respect to the case is improved by increasing the shape accuracy of the contact portion without increasing the flatness of the contact surface as in surface contact. Enhanced. Therefore, accuracy management during molding of the fixing member and the case becomes easy. Further, since the fixing member comes into contact with the case at three points, rattling of the fixing member in the case can be eliminated. Thereby, the stability of the reverberation characteristic can be enhanced.

It is a schematic diagram showing a configuration example of a conventional ultrasonic transducer. 1 is a schematic diagram illustrating a configuration example of an ultrasonic transducer according to a first embodiment of the present invention. It is a schematic diagram showing a configuration example of an ultrasonic transducer according to a second embodiment of the present invention.

  Hereinafter, an ultrasonic transducer 10 according to an embodiment of the present invention will be described.

2A is a central cross-sectional view of the orthogonal coordinate system XZ plane of the ultrasonic transducer 10, and FIG. 2B is a central cross-sectional view of the orthogonal transducer system YZ plane of the ultrasonic transducer 10.
The ultrasonic transducer 10 includes a case 1, a piezoelectric body 2, a fixing member 3, a filler 4, an external connection terminal 5, a conductive adhesive 6, an internal wiring 7, and a sound absorbing member 8.

  When this ultrasonic transducer 10 is used as a transmitter, by applying a drive signal to the external connection terminal 5, the piezoelectric body 2 spreads and vibrates on the XY plane, and extends along the Z axis on the bottom surface of the case 1. The bending vibration is excited to transmit ultrasonic waves. When used as a wave receiver, the bottom surface of the case 1 receives ultrasonic waves and vibrates along the Z axis, so that the piezoelectric body 2 spreads and vibrates to generate a received signal at the external connection terminal 5. .

The case 1 has a bottomed cylindrical shape whose main axis direction is the Z-axis positive direction, and an end portion in the Z-axis positive direction is closed. A holding portion 1 </ b> A for holding the fixing member 3 is provided inside the case 1. The holding portion 1A projects in the case central axis direction on the XY plane.
The piezoelectric body 2 has a polarization axis along the Z axis, and is bonded to the inner bottom surface of the case 1 with an adhesive (not shown). The fixing member 3 is accommodated in the cylinder of the case 1, and the protrusions 3A to 3C, the locking claws 3D and 3E, and the receiving part 3F are provided on the main surface in the positive Z-axis direction. The protrusions 3A to 3C are in contact with the main surface of the holding portion 1A in the negative Z-axis direction. The locking claws 3D and 3E are provided with a return portion at the tip, and the return portion contacts the main surface of the holding portion 1A in the positive Z-axis direction. Thereby, the protrusions 3 </ b> A to 3 </ b> C and the locking claws 3 </ b> D and 3 </ b> E sandwich the holding portion 1 </ b> A, and the fixing member 3 is positioned with respect to the case 1. The filler 4 is filled in a space in the negative direction of the Z axis with respect to the fixing member 3 inside the cylinder of the case 1. The external connection terminal 5 has an end in the positive Z-axis direction inserted and fixed to the fixing member 3, and an end in the negative Z-axis direction protrudes from the inside of the case 1. The sound absorbing member 8 is made of felt or the like, and is supported by the principal surface in the Z-axis positive direction contacting the receiving portion 3F and the surface in the Z-axis negative direction contacting the filler 4. The internal wiring 7 makes the external connection terminal 5 and the piezoelectric body 2 conductive. The conductive adhesive 6 connects the internal wiring 7 and the piezoelectric body 2.

  In the above configuration, the positional accuracy of the fixing member 3 can be increased by increasing the shape accuracy of the protrusions 3A to 3C. Further, in the fixing member 3, only the protrusions 3 </ b> A to 3 </ b> C come into contact with the case 1 from the positive direction of the Z axis to position the fixing member 3, so that wobbling of the fixing member 3 in the case 1 can be suppressed. The locking claws 3 </ b> D and 3 </ b> E can come into contact with the case 1 from the negative direction of the Z axis, and the lifting of the fixing member 3 can be suppressed. With these configurations, the space shape between the bottom surface of the case of the ultrasonic transducer 10 and the fixing member is stabilized, and the reverberation characteristics are also stabilized.

  Next, an ultrasonic transducer 20 according to the second embodiment of the present invention will be described.

  FIG. 3A is a cross-sectional view of the orthogonal coordinate system YZ plane in the ultrasonic transducer 20. FIG. 3B is a perspective view of the fixing member 13 included in the ultrasonic transducer 20.

  The ultrasonic transducer 20 includes an upper cover 11, a piezoelectric body 12, a fixing member 13, a weight 14, an external connection terminal 15, a washer 16, spring-like metal terminals 17A and 17B, sound absorbing members 18A and 18B, and a filler 19.

  When this ultrasonic transducer 20 is used as a transmitter, by applying a drive signal to the external connection terminal 15, the piezoelectric body 12 spreads and vibrates on the XY plane. Then, bending vibration along the Z axis is excited on the bottom surface of the upper cover 11 to transmit ultrasonic waves. When used as a wave receiver, the bottom surface of the upper cover 11 receives ultrasonic waves and vibrates, so that the piezoelectric body 12 spreads and vibrates to generate a received wave signal at the external connection terminal 15.

  The upper cover 11 has a bottomed cylindrical shape whose end in the positive direction of the Z axis is closed. The weight 14 has a cylindrical shape whose central axis is along the Z axis, and an end portion in the positive direction of the Z axis is inserted and fitted into the cylinder of the upper cover 11. The weight 14 includes a holding portion 14A for holding the fixing member 13 and a concave portion 14B for arranging the washer 16. The holding portion 14A projects in the case central axis direction on the XY plane. The upper cover 11 and the weight 14 are combined to form a bottomed cylindrical case. The upper cover 11 corresponds to the inner bottom surface of the case. The washer 16 is a flat plate having an opening, and is inserted into the recess 14 </ b> B of the weight 14.

  The upper cover 11 is preferably made of a metal material such as aluminum, and the weight 14 is preferably made of a metal material having a specific gravity higher than that of the material used for the upper cover 11 such as zinc, iron, or stainless steel. For the production of the upper cover 11, it is possible to improve the coating quality and reduce the cost by using a method such as drawing or forging of a plate material previously coated with a polymer polyester. Further, the upper cover 11 and the weight 14 are connected by a method such as welding, thermocompression bonding, caulking, adhesion, and fitting. For example, in the case of adhesion fitting, the surface of the weight 14 is plated and primer coated. Corrosion resistance may be improved. Further, the surface of the weight 14 may be sandblasted to improve adhesion. Although not shown, the ease of fitting may be improved by providing an R or taper on the head portion of the weight in the positive Z-axis direction. As the type of plating applied to the surface of the weight 14, a copper base nickel or a material that is unlikely to cause a different metal contact corrosion with the upper cover 11, for example, chromium or tin is suitable. A flange portion may be provided on the negative side of the weight 14 in the Z-axis direction for transport chucking during assembly and prevention of disconnection after mounting. The flange portion may have a circular shape concentric with the opening of the weight 14 or may have a polygonal shape. The weight 14 may be divided into a plurality of pieces such as a two-piece structure in the Z-axis direction or the XY axis direction. The weight 14 is connected to the ground electrode via the spring-like metal terminal 17B, but various other methods such as welding, thermocompression bonding, caulking, and adhesion may be used as other connection methods.

  The filler 19 is filled in a space in the negative direction of the Z axis with respect to the fixing member 13 and the sound absorbing member 18A inside the cylinder of the weight 14.

  The piezoelectric body 12 has a polarization axis along the positive direction of the Z axis, and is bonded to the inner bottom surface of the upper cover 11 with an adhesive. A drive electrode (not shown) of the piezoelectric body 12 is connected to the external connection terminal 15 via spring-like metal terminals 17A and 17B.

  The fixing member 13 whose detailed configuration is shown in FIG. 3B includes an upper base 13A, a lower base 13B, a terminal holding portion 13C, projections 21A to 21C, locking claws 22A and 22B, and receiving portions 23A and 23B. The lower base 13B has a substantially disk shape with a part of the chip. The upper base 13A has a substantially square plate shape whose outer shape on the XY plane is smaller than that of the lower base 13B, and is provided in the positive direction of the Z axis of the lower base 13B. The terminal holding portion 13C has a prismatic shape whose outer shape on the XY plane is smaller than that of the lower base 13B and the upper base 13A, and is provided in the negative Z-axis direction of the lower base 13B. The centers of the upper base 13A, the lower base 13B, and the terminal holding portion 13C on the XY plane substantially coincide with each other.

  The protrusions 21A to 21C are provided at three points near the outer periphery of the main surface of the lower base 13B in the positive direction of the Z axis. The locking claws 22A and 22B are provided so that the tip protrudes from the vicinity of the upper base 13A on the main surface in the Z-axis positive direction of the lower base 13B to the position in the Z-axis positive direction from the upper base 13A. A return portion is provided at the tip in the positive axial direction. The receiving portions 23A and 23B have a triangular prism shape extending in the Y-axis positive direction, and are provided on the main surface of the upper base 13A in the Z-axis positive direction.

  The fixing member 13 is accommodated in a cylinder of the weight 14, and the tips of the protrusions 21 </ b> A to 21 </ b> C are positioned with respect to the weight 14 with the main surface of the holding portion 14 </ b> A in the negative Z-axis direction. The locking claws 22A and 22B are inserted into positions in the positive Z-axis direction with respect to the holding portion 14A, and the return portion contacts the main surface in the positive Z-axis direction of the holding portion 14A. Accordingly, the protrusions 21A to 21C and the locking claws 22A and 22B sandwich the holding portion 14A. The terminal holding part 13C passes through the opening of the washer 16 and protrudes in the negative Z-axis direction.

  The end of the external connection terminal 15 in the positive direction of the Z axis is inserted and fixed to the terminal holding portion 13 </ b> C of the fixing member 13, and the end of the negative direction of the Z axis protrudes from the fixing member 13. The sound absorbing member 18A is supported by the main surface in the Z-axis positive direction coming into contact with the receiving portions 23A and 23B, and the main surface in the Z-axis negative direction coming into contact with the lower base 13B of the fixing member 13. The main surface of the sound absorbing member 18B in the negative Z-axis direction is bonded to the upper base 13A of the fixing member 13.

  Even in such a configuration, the fixing member 13 comes into contact with the case at three points and is positioned. Further, the fixing member 13 is prevented from being lifted in the negative Z-axis direction by contact between the return portions of the locking claws 22A and 22B and the holding portion 14A. Therefore, the positional accuracy of the fixing member 13 can be increased by increasing the shape accuracy of the protrusions 21A to 21C. As long as the projections 21A to 21C are supported by three points, the wobbling of the fixing member 13 can be eliminated in the case. Furthermore, since the sound absorbing members 18A and 18B are positioned in contact with the fixed member 13, the positional accuracy of the sound absorbing members 18A and 18B can be increased. Therefore, the shape accuracy of the space inside the case of the ultrasonic transducer 20 is increased, and the reverberation characteristics are improved.

DESCRIPTION OF SYMBOLS 10,20 ... Ultrasonic transducer 1 ... Case 2,12 ... Piezoelectric body 3,13 ... Fixing member 3A, 21A ... Protrusion part 3D, 3E, 22A, 22B ... Locking claw 3F, 23A, 23B ... Receiving part 13A ... Upper part Base 13B ... Lower base 13C ... Terminal holding part 4, 19 ... Filler 5, 15 ... External connection terminal 6 ... Conductive adhesive 7 ... Internal wiring 8, 18A, 18B ... Sound absorbing member 11 ... Upper cover 14 ... Weight 1A, 14A ... Holding part 14B ... Recess 16 ... Washer 17A, 17B ... Spring-like metal terminal

Claims (3)

A bottomed cylindrical case with a closed end in the main axis direction;
A piezoelectric body formed on the inner bottom surface of the case;
A fixing member that is disposed apart from the inner bottom surface portion of the case and is accommodated in the case in a state of contacting the case at three points from the opposite direction of the main axis direction;
An ultrasonic transducer comprising: The case includes a holding portion for holding a fixing member therein,
The fixing member is provided with a locking claw provided with a return portion at the tip on the main surface in the main shaft direction, contacts the holding portion from the opposite direction of the main shaft direction, and the return portion contacts the holding portion from the main shaft direction. The ultrasonic transducer according to claim 1, which comes into contact.   The ultrasonic transducer according to claim 1, further comprising a sound absorbing member accommodated in the case, wherein the fixing member includes a receiving portion that supports the sound absorbing member.

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