WO2013047544A1 - Ultrasonic sensor - Google Patents

Ultrasonic sensor Download PDF

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Publication number
WO2013047544A1
WO2013047544A1 PCT/JP2012/074620 JP2012074620W WO2013047544A1 WO 2013047544 A1 WO2013047544 A1 WO 2013047544A1 JP 2012074620 W JP2012074620 W JP 2012074620W WO 2013047544 A1 WO2013047544 A1 WO 2013047544A1
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WO
WIPO (PCT)
Prior art keywords
electrode
piezoelectric element
case
ultrasonic sensor
vibration
Prior art date
Application number
PCT/JP2012/074620
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French (fr)
Japanese (ja)
Inventor
南部浩司
Original Assignee
株式会社村田製作所
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by 株式会社村田製作所 filed Critical 株式会社村田製作所
Priority to KR1020147007993A priority Critical patent/KR101528890B1/en
Priority to CN201280047255.2A priority patent/CN103828395B/en
Priority to JP2013536315A priority patent/JP5672389B2/en
Publication of WO2013047544A1 publication Critical patent/WO2013047544A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element
    • B06B1/0655—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element of cylindrical shape

Definitions

  • the present invention relates to an ultrasonic sensor having a structure in which a piezoelectric element is joined to a case, for example, an ultrasonic sensor used for a corner sonar, a back sonar, etc. of an automobile.
  • the ultrasonic sensor detects an obstacle or target by intermittently transmitting an ultrasonic pulse signal and receiving a reflected wave reflected after the transmitted ultrasonic pulse signal reaches the obstacle or target.
  • Ultrasonic sensors are used for back sonars, corner sonars of automobiles, and parking spot sensors for detecting distances from obstacles such as side walls in parallel parking.
  • FIG. 6A is a cross-sectional view showing a configuration example of a conventional ultrasonic sensor.
  • the ultrasonic sensor 101 includes a case 102, a piezoelectric element 103, a damping material 104, a substrate 105, a foamable resin 106, pin terminals 107A and 107B, and lead wires 108A and 108B.
  • the case 102 has a bottomed cylindrical shape and is made of a conductive material such as metal.
  • the piezoelectric element 103 is joined to the inner bottom surface of the case 102 with a conductive adhesive or the like.
  • FIG. 6B is a perspective view illustrating a configuration example of the piezoelectric element 103.
  • the piezoelectric element 103 is made of piezoelectric ceramics, and includes a disk-shaped piezoelectric substrate 103C and electrodes 103A and 103B provided on main surfaces of the piezoelectric substrate 103C facing each other.
  • the piezoelectric element 103 is bonded to the case 102 so that the electrode 103A contacts the inner bottom surface of the opening of the case 102.
  • the damping material 104 is provided so as to close the opening of the case 102.
  • the substrate 105 is provided on the damping material 104.
  • the substrate 105 and the damping material 104 are provided with through holes.
  • the foamable resin 106 is injected from one of the through holes into the opening of the case 102 and filled in the case 102 and the through holes.
  • Each of the pin terminals 107A and 107B has a straight bar shape, and is inserted into the opening of the case 102 through one of the through holes.
  • the lead wire 108 ⁇ / b> A is joined to the tip of the pin terminal 107 ⁇ / b> A and the case 102 by solder in the opening of the case 102, and electrically connects the pin terminal 107 ⁇ / b> A and the case 102. For this reason, the pin terminal 107A is electrically connected to the electrode 103A via the lead wire 108A and the case 102.
  • the lead wire 108B is joined to the tip of the pin terminal 107B and the electrode 103B of the piezoelectric element 103 by soldering, and the tip of the pin terminal 107B and the electrode 103B of the piezoelectric element 103 are electrically connected. Connected.
  • the piezoelectric element is joined to the inner bottom surface of the case opening so that the center position of the piezoelectric element coincides with the center of the inner bottom surface of the case opening.
  • the vibration efficiency and the overall sensitivity of the piezoelectric element in the ultrasonic sensor may decrease.
  • a lead wire is directly connected to one electrode of the piezoelectric element, and a lead wire is indirectly connected to the other electrode via a case. For this reason, it is necessary to perform wiring work twice between the piezoelectric element and the case at the time of manufacture, and the work is complicated.
  • an object of the present invention is to realize high bonding accuracy between the piezoelectric element and the case while connecting the wiring member to the electrode of the piezoelectric element without going through the case, and to improve the vibration efficiency and overall sensitivity of the piezoelectric element. It is to realize an ultrasonic sensor having a configuration that can be obtained.
  • the ultrasonic sensor of the present invention includes a case and a piezoelectric element.
  • the case has a bottom surface portion that is a vibration region and has a bottomed cylindrical shape.
  • the piezoelectric element has a piezoelectric substrate, a first electrode, a second electrode, and a third electrode.
  • the piezoelectric substrate has a first surface and a second surface facing the first surface.
  • the first electrode is provided on the first surface.
  • the second electrode is provided on a part of the second surface.
  • the third electrode is provided apart from the second electrode on a part of the second surface, and is connected to the first electrode.
  • the first electrode is joined to the bottom surface, and the center of the piezoelectric element is arranged at a position different from the center of the vibration region in plan view.
  • the area of the region where the second electrode is provided on the second surface of the piezoelectric substrate is different from the area of the region where the third electrode is provided.
  • the second electrode and the third electrode are provided asymmetrically in plan view of the piezoelectric element.
  • the vibration region has a planar shape having a longitudinal direction and a short direction when the bottom surface portion is viewed in plan, and the second electrode and the third electrode are arranged in the short direction. It is preferable.
  • the piezoelectric element is arranged at a position where the center of the piezoelectric element is different from the center of the vibration region in plan view of the bottom surface portion, the vibration efficiency and the overall sensitivity of the piezoelectric element in the ultrasonic sensor are improved. And the characteristics can be improved.
  • the second electrode and the third electrode are provided on the second surface of the piezoelectric substrate, a wiring portion such as a flexible substrate or a lead wire can be directly connected without passing through the case. As a result, there are fewer restrictions on the materials that can be used. Furthermore, the connection between the second electrode and the third electrode and the wiring portion can be performed even after the piezoelectric element is bonded to the case, and the bonding accuracy between the piezoelectric element and the case can be increased.
  • FIG. 1A is a cross-sectional view of the ultrasonic sensor 1 according to the first embodiment of the present invention.
  • FIG. 1B is a plan view of the ultrasonic sensor 1. Note that FIG. 1A shows a cross section at a position indicated by AA ′ in FIG. FIG. 1B shows the back surface of the ultrasonic sensor 1.
  • the ultrasonic sensor 1 includes a case 2, a piezoelectric element 3, a sound absorbing material 4, a reinforcing material 5, a support material 6, a buffer material 7, a vibration damping material 8, a flexible substrate 9, and a terminal holding material 10. And pin terminals 11A and 11B.
  • the case 2 has a bottomed cylindrical shape in which the lower end surface (front surface) in FIG. 1 (A) is closed and the upper end surface (rear surface) in FIG. 1 (A) is open, a cylindrical side wall 2A, and a disk shape. Bottom plate 2B. As shown in FIG. 1B, the opening of the case 2 is circular in plan view.
  • the case 2 is a member made of lightweight aluminum having a high elastic modulus, for example, and is formed by forging.
  • the material of the case 2 is not limited to a conductive material such as aluminum, and may be an insulating material.
  • the bottom plate 2B includes a recess 2B1 and a step 2B2.
  • Recess 2B1 has a bottom surface portion and a side wall portion, and is provided such that a predetermined direction (lateral direction in FIG. 1B) is a short direction, and a direction orthogonal to the short direction is a long direction. . That is, the recess 2B1 is provided so that both ends in the longitudinal direction reach the side wall 2A. Further, the step 2B2 is provided on both sides in the short direction of the recess 2B1.
  • the bottom surface portion of the recess 2B1 becomes the main vibration region of the case 2, and the ultrasonic sensor 1 has a narrow directivity in the longitudinal direction of the recess 2B1 and a wide directivity in the lateral direction.
  • the piezoelectric element 3 has a flat plate shape and spreads in the in-plane direction and vibrates when a driving voltage is applied.
  • the piezoelectric element 3 is disposed inside the recess 2B1 of the case 2 and joined to the bottom plate 2B. Specifically, the piezoelectric element 3 is bonded to the bottom surface portion of the recess 2B1.
  • the piezoelectric element 3 and the bottom plate 2B are joined together to form a bimorph vibrator, and the bottom plate 2B (recessed portion 2B1) bends and vibrates in the vertical direction in FIG.
  • the sound absorbing material 4 is a flat plate made of polyester felt, for example, and is provided to absorb unnecessary ultrasonic waves emitted from the piezoelectric element 3 to the opening side of the case 2.
  • the sound absorbing material 4 is disposed in the recess 2 ⁇ / b> B ⁇ b> 1 of the case 2 and is bonded onto the piezoelectric element 3.
  • the reinforcing material 5 is a ring-shaped member having an opening at the center, and has high acoustic impedance.
  • the reinforcing member 5 is made of a material having higher density and higher rigidity than the material constituting the case 2 such as stainless steel or zinc so as to function as a weight. Note that.
  • the reinforcing material 5 may be made of the same material (aluminum) as the case 2 by adjusting the size such as thickness.
  • the reinforcing member 5 is disposed on the bottom plate 2B of the case 2 so as to contact the inner peripheral surface of the side wall 2A on the bottom plate 2B side, that is, the thick portion, and the stepped portion 2B2.
  • the rigidity of the surrounding portion surrounding the recess 2 ⁇ / b> B ⁇ b> 1 of the case 2 is increased, and the vibration in the bottom plate 2 ⁇ / b> B of the case 2 can be suppressed from being transmitted to the side wall 2 ⁇ / b> A of the case 2.
  • the support member 6 is a ring-shaped member having an opening in the center, and is provided between the side wall 2 ⁇ / b> A of the case 2 and the buffer material 7 in order to support the buffer material 7 without contacting the case 2. .
  • the support material 6 it is possible to suppress the vibration in the bottom plate 2 ⁇ / b> B of the case 2 from being transmitted to the buffer material 7 through the side wall 2 ⁇ / b> A.
  • the buffer material 7 is a cup-shaped member made of an elastic body such as silicone rubber or urethane resin.
  • the shock-absorbing material 7 is provided at the lower portion, and has a convex portion that engages with the opening of the reinforcing member 5, and an opening that is provided at the upper portion and engages with the terminal holding material 10.
  • the terminal holding material 10 is an L-shaped member made of a resin such as polybutylene terephthalate (PBT), and holds the pin terminals 11A and 11B along an axis passing through the center of the opening of the case 2.
  • the lower portion of the terminal holding member 10 is bent so as to engage with an opening provided in the upper portion of the cushioning member 7.
  • the terminal holding material 10 has a convex portion provided on the bottom surface. Further, two through holes through which the pin terminals 11 ⁇ / b> A and 11 ⁇ / b> B are inserted are provided in the central portion of the terminal holding material 10.
  • the pin terminals 11 ⁇ / b> A and 11 ⁇ / b> B are metal linear pins to which the drive voltage of the piezoelectric element 3 is applied, and are held by the terminal holding material 10. Specifically, the pin terminals 11 ⁇ / b> A and 11 ⁇ / b> B are inserted into the through holes of the terminal holding material 10, respectively. The lower ends of the pin terminals 11 ⁇ / b> A and 11 ⁇ / b> B protrude from the through hole of the terminal holding material 10 and are arranged in the opening of the case 2. The upper ends of the pin terminals 11 ⁇ / b> A and 11 ⁇ / b> B protrude from the upper end of the terminal holding member 10 and are arranged outside the case 2.
  • the flexible substrate 9 has a wide band shape, and is a wiring portion that electrically connects the pin terminals 11A and 11B and the piezoelectric element 3.
  • the flexible substrate 9 is bent and disposed in the opening of the case 2, and a part thereof is disposed between the support material 6 and the buffer material 7.
  • the flexible substrate 9 has a first end and a second end. The first end extends along the same direction as the lower ends of the pin terminals 11A and 11B and is connected to the pin terminals 11A and 11B.
  • the second end is connected to the piezoelectric element 3 by a conductive adhesive.
  • the weight of the wiring portion can be reduced as compared with the case where the lead wire is connected to the piezoelectric element by solder as in a conventional ultrasonic sensor. Can do. Thereby, the vibration of the piezoelectric element 3 can be brought closer to an ideal one.
  • the vibration damping material 8 is made of an elastic body such as silicone resin or urethane resin.
  • the damping material 8 is filled in the case 2 and seals the lower ends of the pin terminals 11 ⁇ / b> A and 11 ⁇ / b> B and the flexible substrate 9 disposed in the opening of the case 2.
  • the vibration damping material 8 is filled only in the space on the opening side of the case 2.
  • the damping material 8 has a function of suppressing vibration of the side wall 2 ⁇ / b> A of the case 2 and also has a function of preventing the support material 6 and the buffer material 7 from being detached from the case 2.
  • the vibration in the bottom plate 2B of the case 2 is attenuated by the sound absorbing material 4, the support material 6, and the buffer material 7, and thus almost propagates to the terminal holding material 10 and the pin terminals 11A and 11B. There is nothing. Therefore, vibration leakage from the pin terminals 11A and 11B to the external substrate that occurs when the ultrasonic sensor 1 is mounted on the external substrate is greatly reduced.
  • the support material 6 and the buffer material 7 are difficult to propagate vibration, and the vibration damping material 8 is one that suppresses (vibrates) the vibration of the side wall 2A of the case 2.
  • the support material 6 and the buffer material 7 preferably have a lower elastic modulus than the vibration damping material 8. More specifically, the elastic modulus includes a storage elastic modulus and a loss elastic modulus. It is preferable that the support material 6 and the buffer material 7 have a small storage elastic modulus, and the damping material 8 has a large loss elastic modulus.
  • the support material 6 and the buffer material 7 are preferably made of a silicone resin (silicone rubber), and the vibration damping material 8 is preferably made of a urethane resin.
  • FIG. 2A is a perspective view for explaining a detailed configuration of the piezoelectric element 3.
  • FIG. 2B is a plan view of the ultrasonic sensor 1 as seen through the state in which the piezoelectric element 3 is bonded to the case 2.
  • the piezoelectric element 3 includes electrodes 3A to 3D and a piezoelectric substrate 3E.
  • the piezoelectric substrate 3E is made of a lead zirconate titanate piezoelectric ceramic and has a rectangular flat plate shape in plan view.
  • the electrode 3A corresponds to the first electrode in the present embodiment, and is provided on the entire lower surface, which is the first surface of the piezoelectric substrate 3E.
  • the electrode 3A is joined to the bottom plate 2B of the case 2. Specifically, the electrode 3A is joined to the bottom surface of the recess 2B1.
  • the electrode 3B corresponds to the second electrode in the present embodiment, and is provided on a part of the upper surface which is the second surface of the piezoelectric substrate 3E.
  • the electrode 3C corresponds to the third electrode in the present embodiment, and is provided on a part of the upper surface that is the second surface of the piezoelectric substrate 3E.
  • the electrode 3D is provided on one side surface of the piezoelectric substrate 3E, and is connected to the electrode 3A and the electrode 3C. For this reason, the electrode 3A and the electrode 3C are electrically connected.
  • a linear piezoelectric substrate exposure region parallel to the longitudinal direction of the piezoelectric substrate 3E is provided. .
  • the electrode 3B and the electrode 3C are separated from each other by a predetermined distance, and are arranged in the short direction on the upper surface of the piezoelectric substrate 3E, and are not electrically connected to each other.
  • the area where the electrode 3B is provided on the upper surface of the piezoelectric substrate 3E is different from the area where the electrode 3C is provided, and the area where the electrode 3B is provided is the area where the electrode 3C is provided. Is larger than the area. That is, the area of the electrode 3B is larger than that of the electrode 3C.
  • the electrodes 3B and 3C are arranged side by side while being separated by a predetermined distance, so that the electrodes 3B and 3C are directly connected to the connection region 9A at the second end of the flexible substrate 9.
  • the connection region 9A is connected to the electrode 3B and the electrode 3C in the center in the longitudinal direction of the piezoelectric element 3 and in the region around the electrode non-formation region. Since the electrodes 3A to 3D are configured as described above, the connection region 9A of the flexible substrate 9 is connected to the piezoelectric element 3 after the piezoelectric element 3 is bonded to the bottom plate 2B of the case. Thereby, the joining accuracy of the piezoelectric element 3 and the case 2 can be increased.
  • the piezoelectric element 3 having such a configuration vibrates when a driving voltage is applied between the electrodes 3A and 3B, and a region sandwiched between the electrodes 3A and 3B in the piezoelectric substrate 3E is deformed. It will be. On the other hand, the region sandwiched between the electrodes 3A and 3C in the piezoelectric substrate 3E hardly deforms and therefore hardly contributes to vibration.
  • the area of the area where the electrode 3B is provided on the upper surface, which is the second surface of the piezoelectric substrate 3E, is different from the area of the area where the electrode 3C is provided. Since the electrode 3C is provided asymmetrically, the region contributing to vibration in the piezoelectric element 3 is asymmetrical.
  • the piezoelectric element 3 is joined to the concave portion 2B1 so that the longitudinal direction of the piezoelectric element 3 coincides with the longitudinal direction of the concave portion 2B1 and the short side direction thereof coincides with the short direction of the concave portion 2B1. ing. Then, the piezoelectric element 3 has a plan view of the recess 2B1 so that the center position of the short side direction of the piezoelectric element 3 is different from the center position of the short side direction of the recess 2B1, that is, the center of the short side direction of the piezoelectric element 3 is. Further, the concave portion 2B1 is disposed so as to be offset from the center in the short direction to the one side of the stepped portion 2B2. The piezoelectric element 3 is arranged such that its longitudinal center coincides with the longitudinal center of the recess 2B1.
  • the center of the piezoelectric element 3 is different from the center position of the piezoelectric element 3 and the center position of the recess 2B1. Is offset from the center of the recess 2B1, and the offset dimension of the piezoelectric element 3, that is, the distance between the position of the center of the piezoelectric element 3 and the position of the center of the recess 2B1 is appropriately determined.
  • the vibration efficiency and the overall sensitivity of the element 3 can be improved and the characteristics can be improved.
  • a region sandwiched between the electrodes 3A and 3C in the piezoelectric substrate 3E that hardly contributes to vibration is defined as a bottom plate of the case. Since it can be arranged close to the step 2B2 that is a node of vibration in 2B, it is possible to prevent the vibration of the piezoelectric element 3 from being obstructed and bring the vibration of the ultrasonic sensor 1 closer to an ideal one. it can.
  • connection region 9A at the second end of the flexible substrate 9 is connected to the electrode 3B and the electrode 3C at the center in the longitudinal direction of the piezoelectric element 3 and in the region around the electrode non-formation region. Since 9A can be arranged close to the step 2B2 that becomes a vibration node in the bottom plate 2B of the case, the vibration of the piezoelectric sensor 3 is prevented from being obstructed, and the vibration of the ultrasonic sensor 1 is made more ideal. You can get closer to things.
  • the flexible substrate 9 (not shown) is drawn from the connection region 9A to the electrode 3C side. Thereby, the symmetry of the vibration of the piezoelectric element 3 can be improved, and the vibration of the ultrasonic sensor 1 can be brought closer to an ideal one.
  • the recess 2B1 has a dimension in the short direction of 7.0 mm.
  • the piezoelectric element 3 has a short-side dimension of 5.2 mm and a long-side dimension of 6.5 mm.
  • the electrode 3C has a dimension in the short (width) direction of 0.9 mm.
  • the dimension in the short (width) direction of the electrode non-formation region at the boundary between the electrode 3C and the electrode 3B is 0.4 mm.
  • the electrode 3B has a short (width) dimension of 3.9 mm.
  • the offset dimension between the center of the piezoelectric element 3 and the center of the recess 2B1 is 0.4 mm. That is, the center of the recess 2B1 is positioned at 2.2 mm from the end of the piezoelectric element 3 on the electrode 3B side and at a position of 3.0 mm from the end on the electrode 3C side.
  • FIG. 3A shows the relationship between the electromechanical coupling coefficient Kp /% in the bimorph vibrator including the case 2 and the piezoelectric element 3 and the offset dimension (element shift amount) of the piezoelectric element 3 in the dimension setting example described above.
  • FIG. 3A shows the relationship between the electromechanical coupling coefficient Kp /% in the bimorph vibrator including the case 2 and the piezoelectric element 3 and the offset dimension (element shift amount) of the piezoelectric element 3 in the dimension setting example described above.
  • the offset dimension of the piezoelectric element 3 is larger than the configuration in which the offset dimension of the piezoelectric element 3 is zero.
  • the electromechanical coupling coefficient Kp /% becomes large.
  • the electromechanical coupling coefficient Kp /% is maximized when the offset dimension of the piezoelectric element 3 is a predetermined value (0.4 mm), and in the configuration in which the offset dimension of the piezoelectric element 3 is larger than the predetermined value, the electromechanical coupling coefficient Kp / % Is smaller than the maximum value. Therefore, at least in terms of vibration efficiency of the ultrasonic sensor, it can be seen that vibration efficiency can be maximized by setting the piezoelectric element 3 to a predetermined offset dimension.
  • FIG. 3B is a diagram showing the relationship between the total sensitivity Vpp of the ultrasonic sensor 1 and the offset dimension of the piezoelectric element 3 in the above dimension setting example.
  • the total sensitivity Vpp of the ultrasonic sensor 1 has a positive correlation with the offset dimension of the piezoelectric element 3, and the greater the offset dimension, the higher the total sensitivity Vpp. Accordingly, it can be seen that at least in terms of the total sensitivity Vpp of the ultrasonic sensor 1, it is desirable that the offset dimension of the piezoelectric element 3 be large (for example, 0.5 mm).
  • an example of setting the offset dimension of the piezoelectric element 3 described above is an example of setting the offset dimension to 0.4 mm. It was.
  • the pulling-out direction of the flexible substrate 9 is the longitudinal direction of the piezoelectric element 3
  • interference between the flexible substrate 9 and the side wall 2A of the case 2 is less likely to occur.
  • the offset dimension may be increased to the limit, and the overall sensitivity of the ultrasonic sensor 1 can be further improved.
  • FIG. 4 is a schematic cross-sectional view of the ultrasonic sensor 21 according to the present embodiment.
  • the ultrasonic sensor 21 includes lead wires 29A and 29B instead of the flexible substrate 9 of the ultrasonic sensor 1 according to the above-described embodiment.
  • the other configuration of the ultrasonic sensor 21 is the same as that of the ultrasonic sensor 1 according to the above-described embodiment.
  • the lead wires 29A and 29B are directly connected to the electrodes 3B and 3C (not shown) of the piezoelectric element 3, respectively. In this way, the ultrasonic sensor 21 may be configured. Even in this case, the present invention can be suitably implemented by directly connecting the piezoelectric element 3 and the pin terminals 11A and 11B without using the case 2 and by arranging the piezoelectric element 3 in an offset manner.
  • the electrodes 3 ⁇ / b> B and 3 ⁇ / b> C are provided side by side in the longitudinal direction of the piezoelectric element 33 while being separated by a predetermined distance.
  • the piezoelectric element 33 is arranged offset in the longitudinal direction of the recess 2B1. In such a configuration, the symmetry of the directional beam can be enhanced in the short direction of the recess 2B1. Further, a region sandwiched between the electrode 3A (not shown) and the electrode 3C in the piezoelectric substrate 3E (not shown) that hardly contributes to vibration does not interfere with the side wall 2A or the step 2B2, and the piezoelectric element 33 The size can be increased.
  • the ultrasonic sensor 41 includes a piezoelectric element 43 instead of the piezoelectric element 3 of the above-described embodiment.
  • the other configuration of the ultrasonic sensor 41 is the same as that of the ultrasonic sensor 1 according to the above-described embodiment.
  • FIG. 5B is a plan view of the ultrasonic sensor 41 as seen through the state in which the piezoelectric element 43 is bonded to the case 2.
  • the electrode 3 ⁇ / b> B and the electrode 3 ⁇ / b> C are provided side by side in the short direction of the piezoelectric element 43 while being separated by a predetermined distance.
  • the piezoelectric element 43 is arranged with its own longitudinal direction as the short direction of the recess 2B1 and offset in the longitudinal direction of the recess 2B1.
  • the ultrasonic sensor 51 includes a piezoelectric element 53 instead of the piezoelectric element 3 of the above-described embodiment.
  • the other configuration of the ultrasonic sensor 51 is the same as that of the ultrasonic sensor 1 according to the above-described embodiment.
  • FIG. 5C is a plan view of the ultrasonic sensor 51 as seen through the state in which the piezoelectric element 53 is bonded to the case 2.
  • the electrode 3 ⁇ / b> B and the electrode 3 ⁇ / b> C are provided side by side in the longitudinal direction of the piezoelectric element 53 while being separated by a predetermined distance.
  • the piezoelectric element 53 is arranged with its own longitudinal direction as the short direction of the recess 2B1, and offset in the short direction of the recess 2B1.
  • the present invention can be implemented, but the specific configuration of the ultrasonic sensor is not limited to the above.
  • any specific shape or material such as cushioning material, support material, reinforcement material, support material, sound absorbing material may be used, and cushioning material, support material, reinforcement material, support material, sound absorption material may be It is not always necessary to provide each.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

In the present invention, an ultrasonic sensor is realized in which while connecting an electrode of a piezoelectric element to a wiring member without interposing a case, high connection accuracy between the piezoelectric element and the case can be achieved, and favorable oscillation characteristics and sensitivity characteristics can be obtained. An ultrasonic sensor (1) has the following: a closed-bottom tubular case (2) comprising a recessed part (2B1) having a bottom surface that is an oscillation region; and a piezoelectric element (3) comprising a piezoelectric substrate (3E) having a first surface and a second surface facing the first surface, a first electrode (3A) provided on the first surface, a second electrode (3B) provided to a portion of the second surface, and a third electrode (3C) provided to a portion of the second surface, spaced apart from the second electrode (3B), and connected to the first electrode (3A), and the piezoelectric element is configured so that the first electrode (3A) is connected to the bottom of the recessed part (2B1) and so that the piezoelectric element is disposed at a position such that the center of the bottom surface of the piezoelectric element is, in plan view, different from the center of an oscillation region.

Description

超音波センサUltrasonic sensor
　この発明は、圧電素子をケースに接合した構成の超音波センサ、たとえば、自動車のコーナーソナーやバックソナーなどに用いられる超音波センサに関する。 The present invention relates to an ultrasonic sensor having a structure in which a piezoelectric element is joined to a case, for example, an ultrasonic sensor used for a corner sonar, a back sonar, etc. of an automobile.
　超音波センサは、超音波パルス信号を間欠的に送信し、送信された超音波パルス信号が障害物や物標に到達した後に反射した反射波を受信することにより障害物や物標を検知するものである（例えば特許文献１参照。）。自動車のバックソナー、コーナーソナー、さらには、縦列駐車する際における側壁等の障害物との距離を検知するパーキングスポットセンサ等には超音波センサが用いられている。 The ultrasonic sensor detects an obstacle or target by intermittently transmitting an ultrasonic pulse signal and receiving a reflected wave reflected after the transmitted ultrasonic pulse signal reaches the obstacle or target. (For example, refer to Patent Document 1). Ultrasonic sensors are used for back sonars, corner sonars of automobiles, and parking spot sensors for detecting distances from obstacles such as side walls in parallel parking.
　図６（Ａ）は、従来の超音波センサの構成例を示す断面図である。超音波センサ１０１は、ケース１０２と、圧電素子１０３と、ダンピング材１０４と、基板１０５と、発泡性樹脂１０６と、ピン端子１０７Ａ，１０７Ｂと、リード線１０８Ａ，１０８Ｂと、を備えている。ケース１０２は、有底筒状であり、金属等の導電性を有する材料で構成されている。圧電素子１０３は、ケース１０２の開口内底面に、導電性接着剤などによって接合されている。図６（Ｂ）は、圧電素子１０３の構成例を示す斜視図である。圧電素子１０３は、圧電セラミックスからなり、円板形状の圧電基板１０３Ｃと、圧電基板１０３Ｃの互いに対向する主面にそれぞれ設けられている電極１０３Ａ，１０３Ｂとを有する。圧電素子１０３は、電極１０３Ａがケース１０２の開口内底面に接触するように、ケース１０２に接合されている。 FIG. 6A is a cross-sectional view showing a configuration example of a conventional ultrasonic sensor. The ultrasonic sensor 101 includes a case 102, a piezoelectric element 103, a damping material 104, a substrate 105, a foamable resin 106, pin terminals 107A and 107B, and lead wires 108A and 108B. The case 102 has a bottomed cylindrical shape and is made of a conductive material such as metal. The piezoelectric element 103 is joined to the inner bottom surface of the case 102 with a conductive adhesive or the like. FIG. 6B is a perspective view illustrating a configuration example of the piezoelectric element 103. The piezoelectric element 103 is made of piezoelectric ceramics, and includes a disk-shaped piezoelectric substrate 103C and electrodes 103A and 103B provided on main surfaces of the piezoelectric substrate 103C facing each other. The piezoelectric element 103 is bonded to the case 102 so that the electrode 103A contacts the inner bottom surface of the opening of the case 102.
　また、図６（Ａ）に示すように、ダンピング材１０４は、ケース１０２の開口を閉塞するように設けられている。基板１０５は、ダンピング材１０４上に設けられている。基板１０５およびダンピング材１０４には、貫通孔が設けられている。発泡性樹脂１０６は、貫通孔の一つからケース１０２の開口内に注入され、ケース１０２の内部および貫通孔の内部に充填されている。ピン端子１０７Ａ，１０７Ｂは、それぞれ直線棒状であり、それぞれ貫通孔の一つを介してケース１０２の開口内に挿入されている。リード線１０８Ａは、ケース１０２の開口内において、ピン端子１０７Ａの先端とケース１０２とに半田により接合されており、ピン端子１０７Ａとケース１０２とを電気的に接続している。このため、ピン端子１０７Ａは、リード線１０８Ａとケース１０２とを介して電極１０３Ａに電気的に接続されている。リード線１０８Ｂは、ケース１０２の開口内において、ピン端子１０７Ｂの先端と圧電素子１０３の電極１０３Ｂとに半田により接合されており、ピン端子１０７Ｂの先端と圧電素子１０３の電極１０３Ｂとを電気的に接続している。 Further, as shown in FIG. 6A, the damping material 104 is provided so as to close the opening of the case 102. The substrate 105 is provided on the damping material 104. The substrate 105 and the damping material 104 are provided with through holes. The foamable resin 106 is injected from one of the through holes into the opening of the case 102 and filled in the case 102 and the through holes. Each of the pin terminals 107A and 107B has a straight bar shape, and is inserted into the opening of the case 102 through one of the through holes. The lead wire 108 </ b> A is joined to the tip of the pin terminal 107 </ b> A and the case 102 by solder in the opening of the case 102, and electrically connects the pin terminal 107 </ b> A and the case 102. For this reason, the pin terminal 107A is electrically connected to the electrode 103A via the lead wire 108A and the case 102. In the opening of the case 102, the lead wire 108B is joined to the tip of the pin terminal 107B and the electrode 103B of the piezoelectric element 103 by soldering, and the tip of the pin terminal 107B and the electrode 103B of the piezoelectric element 103 are electrically connected. Connected.
国際公開ＷＯ２００７／０９４１８４号公報International Publication WO2007 / 094184
　上述したような従来構成の超音波センサにおいては、圧電素子が、平面視して、自らの中心の位置とケースの開口内底面の中心とが一致するように、ケースの開口内底面に接合されているが、圧電素子の電極の形状によっては超音波センサにおける圧電素子の振動効率と総合感度とが低下することがあった。また、圧電素子の一方の電極には、リード線が直接接続されていて、他方の電極には、ケースを介して間接的にリード線が接続されている。そのため、製造時には圧電素子とケースとに２度の配線作業が必要であり、作業が煩雑であった。 In the ultrasonic sensor having the conventional configuration as described above, the piezoelectric element is joined to the inner bottom surface of the case opening so that the center position of the piezoelectric element coincides with the center of the inner bottom surface of the case opening. However, depending on the shape of the electrode of the piezoelectric element, the vibration efficiency and the overall sensitivity of the piezoelectric element in the ultrasonic sensor may decrease. In addition, a lead wire is directly connected to one electrode of the piezoelectric element, and a lead wire is indirectly connected to the other electrode via a case. For this reason, it is necessary to perform wiring work twice between the piezoelectric element and the case at the time of manufacture, and the work is complicated.
　また、ケースは良好な導電性を有する材料からなる必要があり、用いることができる材料に制約が大きく、さらに、酸化しやすい金属を用いた場合には酸化防止の処理を必要とすることがあった。 In addition, the case needs to be made of a material having good conductivity, and there are significant restrictions on the materials that can be used. Further, when an easily oxidizable metal is used, an anti-oxidation treatment may be required. It was.
　また、２つのリード線をそれぞれ、ケースを介さずに圧電素子の電極に直接接続することも可能であるが、そのためには、圧電素子の電極にリード線を接続した後で圧電素子をケースに接合する必要がある。その場合には、圧電素子とケースとの接合精度が低下し、良好な振動効率や総合感度を得ることが難しくなる問題があった。 It is also possible to connect the two lead wires directly to the electrode of the piezoelectric element without going through the case. For this purpose, after connecting the lead wire to the electrode of the piezoelectric element, the piezoelectric element is attached to the case. It is necessary to join. In this case, there is a problem that the accuracy of joining the piezoelectric element and the case is lowered, and it is difficult to obtain good vibration efficiency and overall sensitivity.
　そこで本発明の目的は、ケースを介さずに圧電素子の電極に配線部材を接続しながら、圧電素子とケースとの高い接合精度を実現でき、また、良好な圧電素子の振動効率や総合感度を得ることができる構成の超音波センサを実現することにある。 Accordingly, an object of the present invention is to realize high bonding accuracy between the piezoelectric element and the case while connecting the wiring member to the electrode of the piezoelectric element without going through the case, and to improve the vibration efficiency and overall sensitivity of the piezoelectric element. It is to realize an ultrasonic sensor having a configuration that can be obtained.
　本発明の超音波センサは、ケースと、圧電素子と、を備えている。ケースは、振動領域である底面部を有し、有底筒状である。圧電素子は、圧電基板と、第１の電極と、第２の電極と、第３の電極とを有する。圧電基板は、第１の面と第１の面と対向する第２の面とを有する。第１の電極は、第１の面に設けられている。第２の電極は、第２の面の一部に設けられている。第３の電極は、第２の面の一部に第２の電極と離れて設けられており、第１の電極と接続されている。圧電素子は、第１の電極が底面部に接合され、底面部を平面視して自らの中心が振動領域の中心と異なる位置に配置されている。 The ultrasonic sensor of the present invention includes a case and a piezoelectric element. The case has a bottom surface portion that is a vibration region and has a bottomed cylindrical shape. The piezoelectric element has a piezoelectric substrate, a first electrode, a second electrode, and a third electrode. The piezoelectric substrate has a first surface and a second surface facing the first surface. The first electrode is provided on the first surface. The second electrode is provided on a part of the second surface. The third electrode is provided apart from the second electrode on a part of the second surface, and is connected to the first electrode. In the piezoelectric element, the first electrode is joined to the bottom surface, and the center of the piezoelectric element is arranged at a position different from the center of the vibration region in plan view.
　上述の超音波センサにおいて、圧電基板の第２の面における第２の電極が設けられている領域の面積と第３の電極が設けられている領域の面積とが異なることが好ましい。 In the ultrasonic sensor described above, it is preferable that the area of the region where the second electrode is provided on the second surface of the piezoelectric substrate is different from the area of the region where the third electrode is provided.
　上述の超音波センサにおいて、圧電素子を平面視して、第２の電極と第３の電極とが非対称に設けられていることが好ましい。 In the above-described ultrasonic sensor, it is preferable that the second electrode and the third electrode are provided asymmetrically in plan view of the piezoelectric element.
　上述の超音波センサにおいて、振動領域は、底面部を平面視して、長手方向と短手方向とを有する平面形状であり、第２の電極と第３の電極とは短手方向に配列されていることが好ましい。 In the ultrasonic sensor described above, the vibration region has a planar shape having a longitudinal direction and a short direction when the bottom surface portion is viewed in plan, and the second electrode and the third electrode are arranged in the short direction. It is preferable.
　本発明によれば、圧電素子が、底面部を平面視して自らの中心が振動領域の中心と異なる位置に配置されているため、超音波センサにおける圧電素子の振動効率と総合感度とを向上させ、特性を改善することが可能になる。また、第２の電極と第３の電極とが圧電基板の第２の面に設けられているため、ケースを介さずにフレキシブル基板やリード線などの配線部を直接接続することができ、ケースとして利用できる材料に制約が少なくなる。さらに、第２の電極および第３の電極と配線部との接続は、圧電素子をケースに接合した後であっても可能であり、圧電素子とケースとの接合精度の高くすることができる。 According to the present invention, since the piezoelectric element is arranged at a position where the center of the piezoelectric element is different from the center of the vibration region in plan view of the bottom surface portion, the vibration efficiency and the overall sensitivity of the piezoelectric element in the ultrasonic sensor are improved. And the characteristics can be improved. In addition, since the second electrode and the third electrode are provided on the second surface of the piezoelectric substrate, a wiring portion such as a flexible substrate or a lead wire can be directly connected without passing through the case. As a result, there are fewer restrictions on the materials that can be used. Furthermore, the connection between the second electrode and the third electrode and the wiring portion can be performed even after the piezoelectric element is bonded to the case, and the bonding accuracy between the piezoelectric element and the case can be increased.
本発明の第１の実施形態に係る超音波センサの構成例を示す図である。It is a figure which shows the structural example of the ultrasonic sensor which concerns on the 1st Embodiment of this invention. 圧電素子の構成と配置について説明する図である。It is a figure explaining a structure and arrangement | positioning of a piezoelectric element. 圧電素子の配置と電気機械結合係数および総合感度との関係を説明する図である。It is a figure explaining the relationship between arrangement | positioning of a piezoelectric element, an electromechanical coupling coefficient, and total sensitivity. 本発明の第２の実施形態に係る超音波センサの構成例を示す図である。It is a figure which shows the structural example of the ultrasonic sensor which concerns on the 2nd Embodiment of this invention. 本発明の変形例に係る超音波センサの構成例を示す図である。It is a figure which shows the structural example of the ultrasonic sensor which concerns on the modification of this invention. 従来の超音波センサの構成例を示す断面図および従来の超音波センサが備える圧電素子の構成例を示す斜視図である。It is sectional drawing which shows the structural example of the conventional ultrasonic sensor, and a perspective view which shows the structural example of the piezoelectric element with which the conventional ultrasonic sensor is equipped.
《第１の実施形態》
　図１（Ａ）は、本発明の第１の実施形態に係る超音波センサ１の断面図である。図１（Ｂ）は、超音波センサ１の平面図である。なお、図１（Ａ）は、図１（Ｂ）中にＡ－Ａ’で示す位置における断面を示す。図１（Ｂ）は、超音波センサ１の背面を示す。 << First Embodiment >>
FIG. 1A is a cross-sectional view of the ultrasonic sensor 1 according to the first embodiment of the present invention. FIG. 1B is a plan view of the ultrasonic sensor 1. Note that FIG. 1A shows a cross section at a position indicated by AA ′ in FIG. FIG. 1B shows the back surface of the ultrasonic sensor 1.
　超音波センサ１は、ケース２と、圧電素子３と、吸音材４と、補強材５と、支持材６と、緩衝材７と、制振材８と、フレキシブル基板９と、端子保持材１０と、ピン端子１１Ａ，１１Ｂと、を備えている。 The ultrasonic sensor 1 includes a case 2, a piezoelectric element 3, a sound absorbing material 4, a reinforcing material 5, a support material 6, a buffer material 7, a vibration damping material 8, a flexible substrate 9, and a terminal holding material 10. And pin terminals 11A and 11B.
　ケース２は、図１（Ａ）における下端面（正面）が閉塞し、図１（Ａ）における上端面（背面）が開口する有底筒状であり、筒状の側壁２Ａと、円板状の底板２Ｂとを備えている。図１（Ｂ）に示すように、ケース２の開口は平面視して円形である。ケース２は、例えば弾性率が高くて軽量なアルミニウムからなる部材であり、鍛造により形成されている。なお、ケース２の材料は、アルミニウムのような導電性材料に限られず、絶縁性材料であってもよい。 The case 2 has a bottomed cylindrical shape in which the lower end surface (front surface) in FIG. 1 (A) is closed and the upper end surface (rear surface) in FIG. 1 (A) is open, a cylindrical side wall 2A, and a disk shape. Bottom plate 2B. As shown in FIG. 1B, the opening of the case 2 is circular in plan view. The case 2 is a member made of lightweight aluminum having a high elastic modulus, for example, and is formed by forging. The material of the case 2 is not limited to a conductive material such as aluminum, and may be an insulating material.
　側壁２Ａにおいては、背面側の部分は薄肉であって開口部の内径が大きく、底板２Ｂ側の部分は厚肉であって開口部の内径が小さい。底板２Ｂは、凹部２Ｂ１と段部２Ｂ２とを備えている。凹部２Ｂ１は、底面部と側壁部とを有し、所定方向（図１（Ｂ）における横方向）が短手方向となり、短手方向に直交する方向が長手方向となるように設けられている。即ち、凹部２Ｂ１は、長手方向の両端が側壁２Ａまで至るように設けられている。また、段部２Ｂ２は、凹部２Ｂ１の短手方向の両脇に設けられている。凹部２Ｂ１の底面部が、ケース２の主たる振動領域となり、超音波センサ１は、凹部２Ｂ１の長手方向に狭く、短手方向に広い指向性を持つことになる。 In the side wall 2A, the portion on the back side is thin and the inside diameter of the opening is large, and the portion on the bottom plate 2B side is thick and the inside diameter of the opening is small. The bottom plate 2B includes a recess 2B1 and a step 2B2. Recess 2B1 has a bottom surface portion and a side wall portion, and is provided such that a predetermined direction (lateral direction in FIG. 1B) is a short direction, and a direction orthogonal to the short direction is a long direction. . That is, the recess 2B1 is provided so that both ends in the longitudinal direction reach the side wall 2A. Further, the step 2B2 is provided on both sides in the short direction of the recess 2B1. The bottom surface portion of the recess 2B1 becomes the main vibration region of the case 2, and the ultrasonic sensor 1 has a narrow directivity in the longitudinal direction of the recess 2B1 and a wide directivity in the lateral direction.
　圧電素子３は、平板状であり、駆動電圧が印加されると面内方向に広がり振動する。圧電素子３は、ケース２の凹部２Ｂ１の内部に配置されていて、底板２Ｂに接合されている。具体的には、圧電素子３は、凹部２Ｂ１の底面部に接合されている。圧電素子３および底板２Ｂは、互いに接合されてバイモルフ振動子を構成していて、圧電素子３の広がり振動によって、底板２Ｂ（凹部２Ｂ１）は、図１（Ａ）における上下方向に屈曲振動する。 The piezoelectric element 3 has a flat plate shape and spreads in the in-plane direction and vibrates when a driving voltage is applied. The piezoelectric element 3 is disposed inside the recess 2B1 of the case 2 and joined to the bottom plate 2B. Specifically, the piezoelectric element 3 is bonded to the bottom surface portion of the recess 2B1. The piezoelectric element 3 and the bottom plate 2B are joined together to form a bimorph vibrator, and the bottom plate 2B (recessed portion 2B1) bends and vibrates in the vertical direction in FIG.
　吸音材４は、例えばポリエステルフェルトなどからなる平板状のものであり、圧電素子３からケース２の開口側に放出される不要な超音波を吸収するために設けられている。吸音材４は、ケース２の凹部２Ｂ１内に配置されていて、圧電素子３の上に接着されている。 The sound absorbing material 4 is a flat plate made of polyester felt, for example, and is provided to absorb unnecessary ultrasonic waves emitted from the piezoelectric element 3 to the opening side of the case 2. The sound absorbing material 4 is disposed in the recess 2 </ b> B <b> 1 of the case 2 and is bonded onto the piezoelectric element 3.
　補強材５は、中央に開口を有するリング状の部材であり、高い音響インピーダンスを有する。補強材５は、錘として機能するように、ステンレス鋼や亜鉛のような、ケース２を構成する材料よりも密度が高くかつ剛性が高い材料からなる。なお。補強材５は、厚み等のサイズを調整することによってケース２と同じ材料（アルミニウム）からなるものであってもよい。また、補強材５は、側壁２Ａの底板２Ｂ側の部分すなわち厚肉の部分の内周面と段部２Ｂ２とに接するように、ケース２の底板２Ｂ上に配置されている。このように、補強材５が設けられていることにより、ケース２の凹部２Ｂ１を囲む周囲の部分の剛性が高まり、ケース２の底板２Ｂにおける振動がケース２の側壁２Ａへ伝わることを抑制できる。 The reinforcing material 5 is a ring-shaped member having an opening at the center, and has high acoustic impedance. The reinforcing member 5 is made of a material having higher density and higher rigidity than the material constituting the case 2 such as stainless steel or zinc so as to function as a weight. Note that. The reinforcing material 5 may be made of the same material (aluminum) as the case 2 by adjusting the size such as thickness. The reinforcing member 5 is disposed on the bottom plate 2B of the case 2 so as to contact the inner peripheral surface of the side wall 2A on the bottom plate 2B side, that is, the thick portion, and the stepped portion 2B2. Thus, by providing the reinforcing material 5, the rigidity of the surrounding portion surrounding the recess 2 </ b> B <b> 1 of the case 2 is increased, and the vibration in the bottom plate 2 </ b> B of the case 2 can be suppressed from being transmitted to the side wall 2 </ b> A of the case 2.
　支持材６は、中央に開口を有するリング状の部材であり、緩衝材７をケース２に接触させずに支持するために、ケース２の側壁２Ａと緩衝材７との間に設けられている。支持材６が設けられていることにより、ケース２の底板２Ｂにおける振動が側壁２Ａを介して緩衝材７に伝わることを抑制できる。 The support member 6 is a ring-shaped member having an opening in the center, and is provided between the side wall 2 </ b> A of the case 2 and the buffer material 7 in order to support the buffer material 7 without contacting the case 2. . By providing the support material 6, it is possible to suppress the vibration in the bottom plate 2 </ b> B of the case 2 from being transmitted to the buffer material 7 through the side wall 2 </ b> A.
　緩衝材７は、シリコーンゴムやウレタン樹脂などの弾性体からなるカップ状の部材である。緩衝材７は、下部に設けられており、補強材５の開口に係合する凸部と、上部に設けられており、端子保持材１０が係合する開口とを有する。緩衝材７が設けられていることにより、ケース２の底板２Ｂにおける振動が側壁２Ａを介して端子保持材１０に伝わることを抑制できる。 The buffer material 7 is a cup-shaped member made of an elastic body such as silicone rubber or urethane resin. The shock-absorbing material 7 is provided at the lower portion, and has a convex portion that engages with the opening of the reinforcing member 5, and an opening that is provided at the upper portion and engages with the terminal holding material 10. By providing the buffer material 7, it is possible to suppress the vibration in the bottom plate 2 </ b> B of the case 2 from being transmitted to the terminal holding material 10 through the side wall 2 </ b> A.
　端子保持材１０は、ポリブチレンテレフタレート（ＰＢＴ）などの樹脂からなるＬ字状の部材であり、ピン端子１１Ａ，１１Ｂを、ケース２の開口の中心を通る軸に沿う状態で保持している。端子保持材１０の下部は、緩衝材７の上部に設けられている開口に係合するように屈曲している。端子保持材１０は、底面に設けられている凸部を有する。また、端子保持材１０の中央部には、ピン端子１１Ａ，１１Ｂが挿通される２つの貫通孔が設けられている。 The terminal holding material 10 is an L-shaped member made of a resin such as polybutylene terephthalate (PBT), and holds the pin terminals 11A and 11B along an axis passing through the center of the opening of the case 2. The lower portion of the terminal holding member 10 is bent so as to engage with an opening provided in the upper portion of the cushioning member 7. The terminal holding material 10 has a convex portion provided on the bottom surface. Further, two through holes through which the pin terminals 11 </ b> A and 11 </ b> B are inserted are provided in the central portion of the terminal holding material 10.
　ピン端子１１Ａ，１１Ｂは、圧電素子３の駆動電圧が印加される金属製の直線状ピンであり、端子保持材１０によって保持されている。具体的には、ピン端子１１Ａ，１１Ｂは端子保持材１０の貫通孔にそれぞれ挿入されている。ピン端子１１Ａ，１１Ｂの下端部は、端子保持材１０の貫通孔から突出しており、ケース２の開口内に配置されている。ピン端子１１Ａ，１１Ｂの上端部は、端子保持材１０の上端から突出しており、ケース２の外部に配置されている。 The pin terminals 11 </ b> A and 11 </ b> B are metal linear pins to which the drive voltage of the piezoelectric element 3 is applied, and are held by the terminal holding material 10. Specifically, the pin terminals 11 </ b> A and 11 </ b> B are inserted into the through holes of the terminal holding material 10, respectively. The lower ends of the pin terminals 11 </ b> A and 11 </ b> B protrude from the through hole of the terminal holding material 10 and are arranged in the opening of the case 2. The upper ends of the pin terminals 11 </ b> A and 11 </ b> B protrude from the upper end of the terminal holding member 10 and are arranged outside the case 2.
　フレキシブル基板９は、幅広な帯状であり、ピン端子１１Ａ，１１Ｂと圧電素子３とを電気的に接続している配線部である。フレキシブル基板９は、ケース２の開口内に屈曲して配置されており、一部が支持材６と緩衝材７との間に配置されている。フレキシブル基板９は、第一端と第二端とを有する。第一端は、ピン端子１１Ａ，１１Ｂの下端部と同方向に沿って延び、ピン端子１１Ａ，１１Ｂに接続されている。第二端は、圧電素子３に導電性接着剤により接続されている。フレキシブル基板９が導電性接着剤により圧電素子３に接続されているため、従来の超音波センサのようにリード線が半田により圧電素子に接続されている場合よりも配線部の重量を低減することができる。これにより、圧電素子３の振動をより理想的なものに近付けることができる。 The flexible substrate 9 has a wide band shape, and is a wiring portion that electrically connects the pin terminals 11A and 11B and the piezoelectric element 3. The flexible substrate 9 is bent and disposed in the opening of the case 2, and a part thereof is disposed between the support material 6 and the buffer material 7. The flexible substrate 9 has a first end and a second end. The first end extends along the same direction as the lower ends of the pin terminals 11A and 11B and is connected to the pin terminals 11A and 11B. The second end is connected to the piezoelectric element 3 by a conductive adhesive. Since the flexible substrate 9 is connected to the piezoelectric element 3 by a conductive adhesive, the weight of the wiring portion can be reduced as compared with the case where the lead wire is connected to the piezoelectric element by solder as in a conventional ultrasonic sensor. Can do. Thereby, the vibration of the piezoelectric element 3 can be brought closer to an ideal one.
　制振材８は、シリコーン樹脂やウレタン樹脂などの弾性体からなる。制振材８は、ケース２の内部に充填されており、ケース２の開口内に配置されているピン端子１１Ａ，１１Ｂの下端部およびフレキシブル基板９を封止している。但し、支持材６と緩衝材７とにより、ケース２の底板２Ｂ側の空間が覆われているので、制振材８は、ケース２の開口側の空間のみに充填されている。制振材８は、ケース２の側壁２Ａの振動を抑制する機能を有しているとともに、支持材６や緩衝材７がケース２から離脱することを防止する機能も有している。 The vibration damping material 8 is made of an elastic body such as silicone resin or urethane resin. The damping material 8 is filled in the case 2 and seals the lower ends of the pin terminals 11 </ b> A and 11 </ b> B and the flexible substrate 9 disposed in the opening of the case 2. However, since the space on the bottom plate 2 </ b> B side of the case 2 is covered with the support material 6 and the buffer material 7, the vibration damping material 8 is filled only in the space on the opening side of the case 2. The damping material 8 has a function of suppressing vibration of the side wall 2 </ b> A of the case 2 and also has a function of preventing the support material 6 and the buffer material 7 from being detached from the case 2.
　このような構成の超音波センサ１では、ケース２の底板２Ｂにおける振動が、吸音材４や支持材６、緩衝材７により減衰するため、端子保持材１０およびピン端子１１Ａ，１１Ｂに殆ど伝搬することがない。したがって、超音波センサ１を外部基板に実装した際に発生するピン端子１１Ａ，１１Ｂから外部基板への振動漏れが大幅に低減される。 In the ultrasonic sensor 1 having such a configuration, the vibration in the bottom plate 2B of the case 2 is attenuated by the sound absorbing material 4, the support material 6, and the buffer material 7, and thus almost propagates to the terminal holding material 10 and the pin terminals 11A and 11B. There is nothing. Therefore, vibration leakage from the pin terminals 11A and 11B to the external substrate that occurs when the ultrasonic sensor 1 is mounted on the external substrate is greatly reduced.
　なお、支持材６や緩衝材７は振動を伝搬し難いもの、制振材８はケース２の側壁２Ａの振動を抑制（制振）するものであると好適である。支持材６や緩衝材７は、制振材８に比べて弾性率が低いことが好ましい。さらに詳しくは、弾性率には貯蔵弾性率と損失弾性率があり、支持材６や緩衝材７は貯蔵弾性率が小さく、制振材８は損失弾性率が大きいことが好ましい。例えば、支持材６や緩衝材７はシリコーン樹脂（シリコーンゴム）からなり、制振材８はウレタン樹脂からなることが好ましい。 In addition, it is preferable that the support material 6 and the buffer material 7 are difficult to propagate vibration, and the vibration damping material 8 is one that suppresses (vibrates) the vibration of the side wall 2A of the case 2. The support material 6 and the buffer material 7 preferably have a lower elastic modulus than the vibration damping material 8. More specifically, the elastic modulus includes a storage elastic modulus and a loss elastic modulus. It is preferable that the support material 6 and the buffer material 7 have a small storage elastic modulus, and the damping material 8 has a large loss elastic modulus. For example, the support material 6 and the buffer material 7 are preferably made of a silicone resin (silicone rubber), and the vibration damping material 8 is preferably made of a urethane resin.
　図２（Ａ）は、圧電素子３の詳細構成を説明するための斜視図である。図２（Ｂ）は、圧電素子３がケース２に接合されている状態を透視した、超音波センサ１の平面図である。 FIG. 2A is a perspective view for explaining a detailed configuration of the piezoelectric element 3. FIG. 2B is a plan view of the ultrasonic sensor 1 as seen through the state in which the piezoelectric element 3 is bonded to the case 2.
　圧電素子３は、電極３Ａ～３Ｄと、圧電基板３Ｅ、とを備えている。圧電基板３Ｅは、チタン酸ジルコン酸鉛系圧電セラミックスからなり、平面視して長方形の平板状である。電極３Ａは、本実施形態における第１の電極に相当するものであり、圧電基板３Ｅの第１の面である下面の全面に設けられている。電極３Ａは、ケース２の底板２Ｂに接合される。具体的には、電極３Ａは、凹部２Ｂ１の底面部に接合されている。電極３Ｂは、本実施形態における第２の電極に相当するものであり、圧電基板３Ｅの第２の面である上面の一部に設けられている。電極３Ｃは、本実施形態における第３の電極に相当するものであり、圧電基板３Ｅの第２の面である上面の一部に設けられている。電極３Ｄは、圧電基板３Ｅの１つの側面に設けられており、電極３Ａと電極３Ｃとに接続されている。このため、電極３Ａと電極３Ｃとは、電気的に接続されている。圧電基板３Ｅの上面における電極３Ｂが設けられている領域と電極３Ｃが設けられている領域との間には、圧電基板３Ｅの長手方向に平行する直線状の圧電基板露出領域が設けられている。これにより、電極３Ｂと電極３Ｃとは、所定の間隔離れて、圧電基板３Ｅの上面の短手方向に並べて設けられており、互いに電気的に接続されていない。圧電基板３Ｅの上面における電極３Ｂが設けられている領域と電極３Ｃが設けられている領域とは互いに面積が異なり、電極３Ｂが設けられている領域の面積は、電極３Ｃが設けられている領域の面積よりも大きい。すなわち、電極３Ｂの方が電極３Ｃよりも面積が大きい。 The piezoelectric element 3 includes electrodes 3A to 3D and a piezoelectric substrate 3E. The piezoelectric substrate 3E is made of a lead zirconate titanate piezoelectric ceramic and has a rectangular flat plate shape in plan view. The electrode 3A corresponds to the first electrode in the present embodiment, and is provided on the entire lower surface, which is the first surface of the piezoelectric substrate 3E. The electrode 3A is joined to the bottom plate 2B of the case 2. Specifically, the electrode 3A is joined to the bottom surface of the recess 2B1. The electrode 3B corresponds to the second electrode in the present embodiment, and is provided on a part of the upper surface which is the second surface of the piezoelectric substrate 3E. The electrode 3C corresponds to the third electrode in the present embodiment, and is provided on a part of the upper surface that is the second surface of the piezoelectric substrate 3E. The electrode 3D is provided on one side surface of the piezoelectric substrate 3E, and is connected to the electrode 3A and the electrode 3C. For this reason, the electrode 3A and the electrode 3C are electrically connected. Between the region where the electrode 3B is provided on the upper surface of the piezoelectric substrate 3E and the region where the electrode 3C is provided, a linear piezoelectric substrate exposure region parallel to the longitudinal direction of the piezoelectric substrate 3E is provided. . Thereby, the electrode 3B and the electrode 3C are separated from each other by a predetermined distance, and are arranged in the short direction on the upper surface of the piezoelectric substrate 3E, and are not electrically connected to each other. The area where the electrode 3B is provided on the upper surface of the piezoelectric substrate 3E is different from the area where the electrode 3C is provided, and the area where the electrode 3B is provided is the area where the electrode 3C is provided. Is larger than the area. That is, the area of the electrode 3B is larger than that of the electrode 3C.
　このように、電極３Ｂと電極３Ｃとが所定の間隔離れて並べて設けられていることにより、電極３Ｂと電極３Ｃとはフレキシブル基板９の第二端の接続領域９Ａと直接接続される。接続領域９Ａは、圧電素子３の長手方向の中心、かつ、電極非形成領域の周辺の領域において、電極３Ｂと電極３Ｃと接続される。電極３Ａ～３Ｄが上記のように構成されていることにより、圧電素子３がケースの底板２Ｂに接合された後で、フレキシブル基板９の接続領域９Ａが圧電素子３に接続される。これにより、圧電素子３とケース２との接合精度を高くすることができる。 Thus, the electrodes 3B and 3C are arranged side by side while being separated by a predetermined distance, so that the electrodes 3B and 3C are directly connected to the connection region 9A at the second end of the flexible substrate 9. The connection region 9A is connected to the electrode 3B and the electrode 3C in the center in the longitudinal direction of the piezoelectric element 3 and in the region around the electrode non-formation region. Since the electrodes 3A to 3D are configured as described above, the connection region 9A of the flexible substrate 9 is connected to the piezoelectric element 3 after the piezoelectric element 3 is bonded to the bottom plate 2B of the case. Thereby, the joining accuracy of the piezoelectric element 3 and the case 2 can be increased.
　このような構成の圧電素子３は、電極３Ａと電極３Ｂとの間に駆動電圧が印加されることにより、圧電基板３Ｅにおける電極３Ａと電極３Ｂとに挟まれる領域が変形することで、振動することになる。一方、圧電基板３Ｅにおける電極３Ａと電極３Ｃとに挟まれる領域はほとんど変形しないため、振動にほとんど寄与しない。圧電基板３Ｅの第２の面である上面における電極３Ｂが設けられている領域の面積と電極３Ｃが設けられている領域の面積とが異なっており、圧電素子３を平面視して電極３Ｂと電極３Ｃとが非対称に設けられているため、圧電素子３における振動に寄与する領域は非対称である。 The piezoelectric element 3 having such a configuration vibrates when a driving voltage is applied between the electrodes 3A and 3B, and a region sandwiched between the electrodes 3A and 3B in the piezoelectric substrate 3E is deformed. It will be. On the other hand, the region sandwiched between the electrodes 3A and 3C in the piezoelectric substrate 3E hardly deforms and therefore hardly contributes to vibration. The area of the area where the electrode 3B is provided on the upper surface, which is the second surface of the piezoelectric substrate 3E, is different from the area of the area where the electrode 3C is provided. Since the electrode 3C is provided asymmetrically, the region contributing to vibration in the piezoelectric element 3 is asymmetrical.
　圧電素子３は、凹部２Ｂ１を平面視して、自らの長手方向が凹部２Ｂ１の長手方向と一致し、自らの短手方向が凹部２Ｂ１の短手方向と一致するように、凹部２Ｂ１に接合されている。そして、圧電素子３は、凹部２Ｂ１を平面視して、自らの短手方向の中心の位置が凹部２Ｂ１の短手方向の中心の位置と異なるように、すなわち、自らの短手方向の中心が、凹部２Ｂ１の短手方向の中心から、段部２Ｂ２の一方側にオフセットするように配置されている。なお、圧電素子３は、自らの長手方向の中心が、凹部２Ｂ１の長手方向の中心と一致するように配置されている。 The piezoelectric element 3 is joined to the concave portion 2B1 so that the longitudinal direction of the piezoelectric element 3 coincides with the longitudinal direction of the concave portion 2B1 and the short side direction thereof coincides with the short direction of the concave portion 2B1. ing. Then, the piezoelectric element 3 has a plan view of the recess 2B1 so that the center position of the short side direction of the piezoelectric element 3 is different from the center position of the short side direction of the recess 2B1, that is, the center of the short side direction of the piezoelectric element 3 is. Further, the concave portion 2B1 is disposed so as to be offset from the center in the short direction to the one side of the stepped portion 2B2. The piezoelectric element 3 is arranged such that its longitudinal center coincides with the longitudinal center of the recess 2B1.
　このように、圧電素子３における振動に有効に作用する領域が非対称であることを考慮して、圧電素子３の中心の位置と凹部２Ｂ１の中心の位置とが異なるように、圧電素子３の中心を凹部２Ｂ１の中心からオフセットさせ、圧電素子３のオフセット寸法、すなわち、圧電素子３の中心の位置と凹部２Ｂ１の中心の位置との間の距離を適切に定めることで、超音波センサ１における圧電素子３の振動効率と総合感度とを向上させ、特性を改善することが可能になる。 Thus, in consideration of the fact that the region that effectively acts on the vibration in the piezoelectric element 3 is asymmetric, the center of the piezoelectric element 3 is different from the center position of the piezoelectric element 3 and the center position of the recess 2B1. Is offset from the center of the recess 2B1, and the offset dimension of the piezoelectric element 3, that is, the distance between the position of the center of the piezoelectric element 3 and the position of the center of the recess 2B1 is appropriately determined. The vibration efficiency and the overall sensitivity of the element 3 can be improved and the characteristics can be improved.
　また、圧電素子３の短手方向と、凹部２Ｂ１の短手方向とを一致させておくことで、振動にほとんど寄与しない圧電基板３Ｅにおける電極３Ａと電極３Ｃとに挟まれる領域を、ケースの底板２Ｂにおける振動の節となる段部２Ｂ２に近付けて配置することができるため、圧電素子３の振動が阻害されることを防いで、超音波センサ１の振動をより理想的なものに近付けることができる。 Further, by making the short direction of the piezoelectric element 3 coincide with the short direction of the recess 2B1, a region sandwiched between the electrodes 3A and 3C in the piezoelectric substrate 3E that hardly contributes to vibration is defined as a bottom plate of the case. Since it can be arranged close to the step 2B2 that is a node of vibration in 2B, it is possible to prevent the vibration of the piezoelectric element 3 from being obstructed and bring the vibration of the ultrasonic sensor 1 closer to an ideal one. it can.
　また、フレキシブル基板９の第二端の接続領域９Ａが、圧電素子３の長手方向の中心、かつ、電極非形成領域の周辺の領域において、電極３Ｂと電極３Ｃと接続されることにより、接続領域９Ａをケースの底板２Ｂにおける振動の節となる段部２Ｂ２に近付けて配置することができるため、圧電素子３の振動が阻害されることを防いで、超音波センサ１の振動をより理想的なものに近付けることができる。なお、ここでは、フレキシブル基板９（不図示）を、接続領域９Ａから、電極３Ｃ側に引き出すようにしている。これにより、圧電素子３の振動の対称性を高めて、超音波センサ１の振動をより理想的なものに近付けることができる。 In addition, the connection region 9A at the second end of the flexible substrate 9 is connected to the electrode 3B and the electrode 3C at the center in the longitudinal direction of the piezoelectric element 3 and in the region around the electrode non-formation region. Since 9A can be arranged close to the step 2B2 that becomes a vibration node in the bottom plate 2B of the case, the vibration of the piezoelectric sensor 3 is prevented from being obstructed, and the vibration of the ultrasonic sensor 1 is made more ideal. You can get closer to things. Here, the flexible substrate 9 (not shown) is drawn from the connection region 9A to the electrode 3C side. Thereby, the symmetry of the vibration of the piezoelectric element 3 can be improved, and the vibration of the ultrasonic sensor 1 can be brought closer to an ideal one.
　なお、具体的な寸法の設定例について説明しておくと、凹部２Ｂ１は、短手方向の寸法が７．０ｍｍである。圧電素子３は、短手方向の寸法が５．２ｍｍであり、長手方向の寸法が６．５ｍｍである。電極３Ｃは短手（幅）方向の寸法が０．９ｍｍである。電極３Ｃと電極３Ｂとの境界の電極非形成領域の短手(幅)方向の寸法が０．４ｍｍである。電極３Ｂは、短手（幅）方向の寸法が３．９ｍｍである。そして、圧電素子３の中心と凹部２Ｂ１の中心とのオフセット寸法は０．４ｍｍである。即ち、圧電素子３の電極３Ｂ側の端部から２．２ｍｍで、電極３Ｃ側の端部から３．０ｍｍの位置に、凹部２Ｂ１の中心が位置する。 In addition, a specific example of setting dimensions will be described. The recess 2B1 has a dimension in the short direction of 7.0 mm. The piezoelectric element 3 has a short-side dimension of 5.2 mm and a long-side dimension of 6.5 mm. The electrode 3C has a dimension in the short (width) direction of 0.9 mm. The dimension in the short (width) direction of the electrode non-formation region at the boundary between the electrode 3C and the electrode 3B is 0.4 mm. The electrode 3B has a short (width) dimension of 3.9 mm. The offset dimension between the center of the piezoelectric element 3 and the center of the recess 2B1 is 0.4 mm. That is, the center of the recess 2B1 is positioned at 2.2 mm from the end of the piezoelectric element 3 on the electrode 3B side and at a position of 3.0 mm from the end on the electrode 3C side.
　ここで、超音波センサ１の振動特性について、ＦＥＭ解析結果に基づいて説明する。図３（Ａ）は、上記した寸法設定例における、ケース２と圧電素子３とからなるバイモルフ振動子における電気機械結合係数Ｋｐ／％と、圧電素子３のオフセット寸法（素子ずらし量）との関係を示す図である。 Here, the vibration characteristics of the ultrasonic sensor 1 will be described based on the FEM analysis results. FIG. 3A shows the relationship between the electromechanical coupling coefficient Kp /% in the bimorph vibrator including the case 2 and the piezoelectric element 3 and the offset dimension (element shift amount) of the piezoelectric element 3 in the dimension setting example described above. FIG.
　図３（Ａ）に示すように、圧電素子３の中心が凹部２Ｂ１の中心と一致する、すなわち圧電素子３のオフセット寸法が０である構成よりも、圧電素子３のオフセット寸法がより大きい構成では、電気機械結合係数Ｋｐ／％が大きなものになる。電気機械結合係数Ｋｐ／％は、圧電素子３のオフセット寸法が所定値（０．４ｍｍ）で最大となり、圧電素子３のオフセット寸法がその所定値よりもさらに大きい構成では、電気機械結合係数Ｋｐ／％は最大値よりも小さいものになる。したがって、少なくとも超音波センサの振動効率の面では、圧電素子３を所定のオフセット寸法とすることで、振動効率を最大化できることが分かる。 As shown in FIG. 3A, in the configuration in which the center of the piezoelectric element 3 coincides with the center of the recess 2B1, that is, the offset dimension of the piezoelectric element 3 is larger than the configuration in which the offset dimension of the piezoelectric element 3 is zero. The electromechanical coupling coefficient Kp /% becomes large. The electromechanical coupling coefficient Kp /% is maximized when the offset dimension of the piezoelectric element 3 is a predetermined value (0.4 mm), and in the configuration in which the offset dimension of the piezoelectric element 3 is larger than the predetermined value, the electromechanical coupling coefficient Kp / % Is smaller than the maximum value. Therefore, at least in terms of vibration efficiency of the ultrasonic sensor, it can be seen that vibration efficiency can be maximized by setting the piezoelectric element 3 to a predetermined offset dimension.
　次に、超音波センサ１の感度特性について、サンプル試験結果（ｎ＝３）に基づいて説明する。図３（Ｂ）は、上記した寸法設定例における、超音波センサ１の総合感度Ｖｐｐと、圧電素子３のオフセット寸法との関係を示す図である。 Next, sensitivity characteristics of the ultrasonic sensor 1 will be described based on sample test results (n = 3). FIG. 3B is a diagram showing the relationship between the total sensitivity Vpp of the ultrasonic sensor 1 and the offset dimension of the piezoelectric element 3 in the above dimension setting example.
　超音波センサ１の総合感度Ｖｐｐは、圧電素子３のオフセット寸法と正の相関関係を持ち、オフセット寸法が大きければ総合感度Ｖｐｐが高いものになった。したがって、少なくとも超音波センサ１の総合感度Ｖｐｐの面では、圧電素子３のオフセット寸法は大きいほうが（例えば、０．５ｍｍであれば）望ましいことが分かる。 The total sensitivity Vpp of the ultrasonic sensor 1 has a positive correlation with the offset dimension of the piezoelectric element 3, and the greater the offset dimension, the higher the total sensitivity Vpp. Accordingly, it can be seen that at least in terms of the total sensitivity Vpp of the ultrasonic sensor 1, it is desirable that the offset dimension of the piezoelectric element 3 be large (for example, 0.5 mm).
　ただし、現実的には、圧電素子３のオフセット寸法が大きすぎると、圧電素子３と接続されるフレキシブル基板９の配置も大きくオフセットされて、フレキシブル基板９がケース２の側壁２Ａと干渉し易くなる。フレキシブル基板９がケース２の側壁２Ａに干渉すると、不要な振動がフレキシブル基板９から側壁２Ａに伝わることになり、特性が劣化する恐れがある。したがって、そのような干渉を防ぎながら、振動特性と感度特性とを良好なものにするために、上述の圧電素子３のオフセット寸法の設定例としては、オフセット寸法０．４ｍｍとした設定例を示した。 However, in reality, if the offset dimension of the piezoelectric element 3 is too large, the arrangement of the flexible substrate 9 connected to the piezoelectric element 3 is also greatly offset, and the flexible substrate 9 easily interferes with the side wall 2A of the case 2. . When the flexible substrate 9 interferes with the side wall 2A of the case 2, unnecessary vibrations are transmitted from the flexible substrate 9 to the side wall 2A, which may deteriorate the characteristics. Therefore, in order to improve vibration characteristics and sensitivity characteristics while preventing such interference, an example of setting the offset dimension of the piezoelectric element 3 described above is an example of setting the offset dimension to 0.4 mm. It was.
　なお、フレキシブル基板９の引き出し方向を圧電素子３の長手方向とすれば、フレキシブル基板９とケース２の側壁２Ａとの干渉は生じにくくなる。その場合には、オフセット寸法を限界まで大きくしても良く、超音波センサ１の総合感度をさらに良好なものにすることが可能になる。 In addition, if the pulling-out direction of the flexible substrate 9 is the longitudinal direction of the piezoelectric element 3, interference between the flexible substrate 9 and the side wall 2A of the case 2 is less likely to occur. In that case, the offset dimension may be increased to the limit, and the overall sensitivity of the ultrasonic sensor 1 can be further improved.
≪第２の実施形態≫
　次に、本発明の第２の実施形態に係る超音波センサ２１について説明する。 << Second Embodiment >>
Next, an ultrasonic sensor 21 according to a second embodiment of the present invention will be described.
　図４は、本実施形態に係る超音波センサ２１の模式断面図である。 FIG. 4 is a schematic cross-sectional view of the ultrasonic sensor 21 according to the present embodiment.
　超音波センサ２１は、前述の実施形態に係る超音波センサ１のフレキシブル基板９に替えて、リード線２９Ａ，２９Ｂを備える。超音波センサ２１は、その他の構成は前述の実施形態に係る超音波センサ１と同じである。リード線２９Ａ，２９Ｂはそれぞれ、圧電素子３の電極３Ｂ、３Ｃ（不図示）に直接接続されている。このように超音波センサ２１は構成してもよい。その場合にも、ケース２を介することなく、圧電素子３とピン端子１１Ａ，１１Ｂとの間を直接的に接続するとともに、圧電素子３をオフセット配置することにより、本発明は好適に実施できる。 The ultrasonic sensor 21 includes lead wires 29A and 29B instead of the flexible substrate 9 of the ultrasonic sensor 1 according to the above-described embodiment. The other configuration of the ultrasonic sensor 21 is the same as that of the ultrasonic sensor 1 according to the above-described embodiment. The lead wires 29A and 29B are directly connected to the electrodes 3B and 3C (not shown) of the piezoelectric element 3, respectively. In this way, the ultrasonic sensor 21 may be configured. Even in this case, the present invention can be suitably implemented by directly connecting the piezoelectric element 3 and the pin terminals 11A and 11B without using the case 2 and by arranging the piezoelectric element 3 in an offset manner.
≪変形例≫
　次に、本発明の変形例に係る超音波センサ３１～５１について説明する。 ≪Modification≫
Next, ultrasonic sensors 31 to 51 according to modifications of the present invention will be described.

　圧電素子３３では、電極３Ｂと電極３Ｃとは、所定の間隔離れて、圧電素子３３の長手方向に並べて設けられている。圧電素子３３は、凹部２Ｂ１の長手方向にオフセットして配置されている。このような構成では、凹部２Ｂ１の短手方向で指向性ビームの対称性を高めることができる。また、振動にほとんど寄与しない圧電基板３Ｅ（図示せず）における電極３Ａ（図示せず）と電極３Ｃとに挟まれる領域が、側壁２Ａや段部２Ｂ２に干渉することが無く、圧電素子３３のサイズが大きくすることができる。
In the piezoelectric element 33, the electrodes 3 </ b> B and 3 </ b> C are provided side by side in the longitudinal direction of the piezoelectric element 33 while being separated by a predetermined distance. The piezoelectric element 33 is arranged offset in the longitudinal direction of the recess 2B1. In such a configuration, the symmetry of the directional beam can be enhanced in the short direction of the recess 2B1. Further, a region sandwiched between the electrode 3A (not shown) and the electrode 3C in the piezoelectric substrate 3E (not shown) that hardly contributes to vibration does not interfere with the side wall 2A or the step 2B2, and the piezoelectric element 33 The size can be increased.
　超音波センサ４１は、前述の実施形態の圧電素子３に替えて、圧電素子４３を備える。超音波センサ４１は、その他の構成は前述の実施形態に係る超音波センサ１と同じである。図５（Ｂ）は、圧電素子４３がケース２に接合されている状態を透視した、超音波センサ４１の平面図である。 The ultrasonic sensor 41 includes a piezoelectric element 43 instead of the piezoelectric element 3 of the above-described embodiment. The other configuration of the ultrasonic sensor 41 is the same as that of the ultrasonic sensor 1 according to the above-described embodiment. FIG. 5B is a plan view of the ultrasonic sensor 41 as seen through the state in which the piezoelectric element 43 is bonded to the case 2.
　圧電素子４３では、電極３Ｂと電極３Ｃとは、所定の間隔離れて、圧電素子４３の短手方向に並べて設けられている。圧電素子４３は、自らの長手方向を凹部２Ｂ１の短手方向とし、凹部２Ｂ１の長手方向にオフセットして配置されている。 In the piezoelectric element 43, the electrode 3 </ b> B and the electrode 3 </ b> C are provided side by side in the short direction of the piezoelectric element 43 while being separated by a predetermined distance. The piezoelectric element 43 is arranged with its own longitudinal direction as the short direction of the recess 2B1 and offset in the longitudinal direction of the recess 2B1.
　超音波センサ５１は、前述の実施形態の圧電素子３に替えて、圧電素子５３を備える。超音波センサ５１は、その他の構成は前述の実施形態に係る超音波センサ１と同じである。図５（Ｃ）は、圧電素子５３がケース２に接合されている状態を透視した、超音波センサ５１の平面図である。 The ultrasonic sensor 51 includes a piezoelectric element 53 instead of the piezoelectric element 3 of the above-described embodiment. The other configuration of the ultrasonic sensor 51 is the same as that of the ultrasonic sensor 1 according to the above-described embodiment. FIG. 5C is a plan view of the ultrasonic sensor 51 as seen through the state in which the piezoelectric element 53 is bonded to the case 2.
　圧電素子５３では、電極３Ｂと電極３Ｃとは、所定の間隔離れて、圧電素子５３の長手方向に並べて設けられている。圧電素子５３は、自らの長手方向を凹部２Ｂ１の短手方向とし、凹部２Ｂ１の短手方向にオフセットして配置されている。 In the piezoelectric element 53, the electrode 3 </ b> B and the electrode 3 </ b> C are provided side by side in the longitudinal direction of the piezoelectric element 53 while being separated by a predetermined distance. The piezoelectric element 53 is arranged with its own longitudinal direction as the short direction of the recess 2B1, and offset in the short direction of the recess 2B1.
　以上の各実施形態で説明したように本発明は実施することができるが、超音波センサの具体的な構成は、上述のものに限られるものではない。例えば、緩衝材や、支持材、補強材、支持材、吸音材などの具体的形状や材料はどのようなものでもよく、また、緩衝材や、支持材、補強材、支持材、吸音材はそれぞれ必ずしも設けなくてもよい。 As described in the above embodiments, the present invention can be implemented, but the specific configuration of the ultrasonic sensor is not limited to the above. For example, any specific shape or material such as cushioning material, support material, reinforcement material, support material, sound absorbing material may be used, and cushioning material, support material, reinforcement material, support material, sound absorption material may be It is not always necessary to provide each.
１，２１，３１，４１，５１…超音波センサ
２…ケース
２Ａ…側壁
２Ｂ…底板
２Ｂ１…凹部
２Ｂ２…段部
３，３３，４３，５３…圧電素子
３Ａ～３Ｄ…駆動電極
３Ｅ…圧電基板
４…吸音材
５…補強材
６…支持材
７…緩衝材
８…制振材
９…フレキシブル基板
９Ａ…接続領域
１０…端子保持材
１１Ａ，１１Ｂ…ピン端子
２９Ａ，２９Ｂ…リード線 1, 2, 31, 41, 51 ... Ultrasonic sensor 2 ... Case 2A ... Side wall 2B ... Bottom plate 2B1 ... Recess 2B2 ... Steps 3, 33, 43, 53 ... Piezoelectric elements 3A-3D ... Drive electrode 3E ... Piezoelectric substrate 4 ... Sound absorbing material 5 ... Reinforcing material 6 ... Support material 7 ... Buffer material 8 ... Damping material 9 ... Flexible substrate 9A ... Connection region 10 ... Terminal holding materials 11A and 11B ... Pin terminals 29A and 29B ... Lead wires

Claims (4)

  1. 　振動領域である底面部を有する有底筒状のケースと、
    　第１の面と前記第１の面と対向する第２の面とを有する圧電基板と、前記第１の面に設けられている第１の電極と、前記第２の面の一部に設けられている第２の電極と、前記第２の面の一部に前記第２の電極と離れて設けられており、前記第１の電極と接続されている第３の電極とを有し、前記第１の電極が前記底面部に接合され、前記底面部を平面視して自らの中心が前記振動領域の中心と異なる位置に配置されている圧電素子と、
    　を備える、超音波センサ。     A bottomed cylindrical case having a bottom surface which is a vibration region;
    A piezoelectric substrate having a first surface and a second surface opposite to the first surface, a first electrode provided on the first surface, and a portion of the second surface A second electrode that is provided, and a third electrode that is provided apart from the second electrode on a part of the second surface and is connected to the first electrode, A piezoelectric element in which the first electrode is bonded to the bottom surface, and the center of the first electrode is arranged at a position different from the center of the vibration region in plan view of the bottom surface;
    An ultrasonic sensor.
  2. 　前記圧電基板の前記第２の面における前記第２の電極が設けられている領域の面積と前記第３の電極が設けられている領域の面積とが異なる、請求項１に記載の超音波センサ。 The ultrasonic sensor according to claim 1, wherein an area of the region where the second electrode is provided on the second surface of the piezoelectric substrate is different from an area of the region where the third electrode is provided. .
  3. 　前記圧電素子を平面視して、前記第２の電極と前記第３の電極とが非対称に設けられている、請求項１に記載の超音波センサ。 The ultrasonic sensor according to claim 1, wherein the second electrode and the third electrode are provided asymmetrically in a plan view of the piezoelectric element.
  4. 　前記振動領域は、前記底面部を平面視して、長手方向と短手方向とを有する平面形状であり、
    　前記第２の電極と前記第３の電極とは前記短手方向に配列されている、請求項１～３のいずれかに記載の超音波センサ。     The vibration region is a planar shape having a longitudinal direction and a lateral direction when the bottom surface portion is viewed in plan view,
    The ultrasonic sensor according to any one of claims 1 to 3, wherein the second electrode and the third electrode are arranged in the lateral direction.
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016147917A1 (en) * 2015-03-16 2016-09-22 株式会社村田製作所 Ultrasonic sensor
JP2018093449A (en) * 2016-12-07 2018-06-14 キヤノン株式会社 Ultrasonic probe, ultrasonic unit, and subject information acquisition device
JP2020108113A (en) * 2018-12-28 2020-07-09 京セラ株式会社 Ultrasonic sensor
JPWO2021171819A1 (en) * 2020-02-26 2021-09-02
JP2021141475A (en) * 2020-03-06 2021-09-16 Tdk株式会社 Piezoelectric device
WO2021187243A1 (en) * 2020-03-20 2021-09-23 株式会社Ｓｏｋｅｎ Ultrasonic transducer, ultrasonic sensor, object detection device, object detection method, and object detection program
JP2021183951A (en) * 2020-05-22 2021-12-02 株式会社Soken Ultrasonic sensor mounting structure
JP2021197617A (en) * 2020-06-12 2021-12-27 株式会社Soken Ultrasonic transducer
US11397254B2 (en) * 2018-08-09 2022-07-26 Seiko Epson Corporation Ultrasonic device and ultrasonic sensor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104677399B (en) * 2014-11-24 2017-12-05 麦克思智慧资本股份有限公司 Ultrasonic sensor
WO2019087266A1 (en) * 2017-10-30 2019-05-09 オリンパス株式会社 Ultrasonic transducer, ultrasonic endoscope, and ultrasonic transducer manufacturing method

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06184A (en) * 1992-06-19 1994-01-11 Matsushita Electric Ind Co Ltd Ultrasonic probe
JP2000152387A (en) * 1998-11-05 2000-05-30 Nippon Ceramic Co Ltd Ultrasonic wave transmitter-receiver
JP2008531110A (en) * 2005-02-22 2008-08-14 ヒューマンスキャン・カンパニー・リミテッド Multilayer ultrasonic transducer and manufacturing method thereof
WO2011090201A1 (en) * 2010-01-25 2011-07-28 株式会社村田製作所 Ultrasonic vibration device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001128293A (en) * 1999-10-28 2001-05-11 Murata Mfg Co Ltd Piezoelectric device
JP4809410B2 (en) * 2008-09-29 2011-11-09 日本電波工業株式会社 Piezoelectric device and manufacturing method thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06184A (en) * 1992-06-19 1994-01-11 Matsushita Electric Ind Co Ltd Ultrasonic probe
JP2000152387A (en) * 1998-11-05 2000-05-30 Nippon Ceramic Co Ltd Ultrasonic wave transmitter-receiver
JP2008531110A (en) * 2005-02-22 2008-08-14 ヒューマンスキャン・カンパニー・リミテッド Multilayer ultrasonic transducer and manufacturing method thereof
WO2011090201A1 (en) * 2010-01-25 2011-07-28 株式会社村田製作所 Ultrasonic vibration device

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JP2018093449A (en) * 2016-12-07 2018-06-14 キヤノン株式会社 Ultrasonic probe, ultrasonic unit, and subject information acquisition device
US11397254B2 (en) * 2018-08-09 2022-07-26 Seiko Epson Corporation Ultrasonic device and ultrasonic sensor
JP7061559B2 (en) 2018-12-28 2022-04-28 京セラ株式会社 Ultrasonic sensor
JP2020108113A (en) * 2018-12-28 2020-07-09 京セラ株式会社 Ultrasonic sensor
DE112021000436T5 (en) 2020-02-26 2022-10-13 Murata Manufacturing Co., Ltd. ULTRASONIC SENSOR
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US12044808B2 (en) 2020-03-20 2024-07-23 Denso Corporation Ultrasonic transducer, ultrasonic sensor, object detection apparatus, object detection method, and object detection program
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JP7435282B2 (en) 2020-06-12 2024-02-21 株式会社Soken ultrasonic transducer
JP2021197617A (en) * 2020-06-12 2021-12-27 株式会社Soken Ultrasonic transducer

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JP5672389B2 (en) 2015-02-18
JPWO2013047544A1 (en) 2015-03-26

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