WO2022185763A1 - Ultrasonic sensor - Google Patents

Ultrasonic sensor Download PDF

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Publication number
WO2022185763A1
WO2022185763A1 PCT/JP2022/002012 JP2022002012W WO2022185763A1 WO 2022185763 A1 WO2022185763 A1 WO 2022185763A1 JP 2022002012 W JP2022002012 W JP 2022002012W WO 2022185763 A1 WO2022185763 A1 WO 2022185763A1
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Prior art keywords
ultrasonic sensor
flat portion
convex portion
axial direction
convex
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PCT/JP2022/002012
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French (fr)
Japanese (ja)
Inventor
貴大 山本
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株式会社村田製作所
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Publication of WO2022185763A1 publication Critical patent/WO2022185763A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers

Definitions

  • the present disclosure relates to ultrasonic sensors.
  • Patent Document 1 US Pat. No. 9,383,443 (Patent Document 1) is cited as a document disclosing the configuration of an ultrasonic sensor.
  • the ultrasonic sensor described in US Pat. No. 5,900,005 comprises a housing, a transducer element and at least one mass element.
  • the housing has side walls and a base surface configured as a diaphragm.
  • Transducer elements are positioned on the base surface for generating and detecting ultrasonic vibrations.
  • At least one mass element is arranged on the base surface.
  • the at least one mass element is arranged such that at least one of force and torque exerted by the at least one mass element on the diaphragm increases with increasing vibration frequency.
  • At least one mass element is centrally located on the base surface.
  • At least one mass element has an impedance that changes the tertiary mode of vibration of the diaphragm such that the tertiary mode of vibration of the diaphragm approaches the primary mode of vibration of the diaphragm.
  • At least one mass element can transmit and receive two ultrasonic signals with different frequencies so as to correspond to two vibration modes.
  • the present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide an ultrasonic sensor capable of transmitting and receiving two ultrasonic signals having different frequencies and having a piezoelectric element attached to the bottom thereof. .
  • An ultrasonic sensor based on the present disclosure includes a bottomed cylindrical case including a bottom, a peripheral wall extending from the bottom along the axial direction of the central axis of the bottom perpendicular to the bottom, and a bottom inside the case on the bottom. and an arranged piezoelectric element.
  • the peripheral wall has an open end opposite the bottom. The open end is provided with a first projection and a second projection, each extending along the axial direction, at different positions in the circumferential direction of the peripheral wall.
  • Each of the first convex portion and the second convex portion is inclined in a direction approaching the central axis when the bottom portion is convexly curved to one side in the axial direction during vibration at the frequency of the first vibration mode. do.
  • Each of the first convex portion and the second convex portion is inclined away from the central axis when the bottom portion is convexly curved to one side in the axial direction during vibration at the frequency of the second vibration mode. do.
  • an ultrasonic sensor capable of transmitting and receiving two ultrasonic signals with different frequencies and having a piezoelectric element easily attached to the bottom.
  • FIG. 1 is a perspective view of an ultrasonic sensor according to an embodiment of the present invention, viewed from the side opposite to the bottom side;
  • FIG. FIG. 2 is a plan view of the ultrasonic sensor of the embodiment of the present invention viewed from the side opposite to the bottom side; It is the bottom view which looked at the ultrasonic sensor of embodiment of this invention from the bottom part side.
  • 1 is a cross-sectional view of an ultrasonic sensor according to an embodiment of the invention;
  • FIG. 1 is a block diagram showing the configuration of an ultrasound system according to an embodiment of the present invention;
  • FIG. FIG. 10 is a bottom view showing one state by simulation when the case of the ultrasonic sensor of the example is vibrating at the frequency of the first vibration mode.
  • FIG. 4 is a side view showing one state by simulation when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the first vibration mode.
  • FIG. 10 is a bottom view showing one state by simulation when the case of the ultrasonic sensor of the example is vibrating at the frequency of the second vibration mode.
  • FIG. 10 is a side view showing a state by simulation when the case of the ultrasonic sensor of the embodiment is vibrating at the frequency of the second vibration mode.
  • FIG. 11 is a perspective view of an ultrasonic sensor that is a modification of the embodiment of the present invention, viewed from the side opposite to the bottom side.
  • FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 10 of an ultrasonic sensor that is a modification of the embodiment of the present invention;
  • FIG. 1 is a perspective view of an ultrasonic sensor according to an embodiment of the present invention, viewed from the side opposite to the bottom side.
  • FIG. 2 is a plan view of the ultrasonic sensor of the embodiment of the present invention viewed from the side opposite to the bottom side.
  • FIG. 3 is a bottom view of the ultrasonic sensor of the embodiment of the present invention viewed from the bottom side.
  • FIG. 4 is a cross-sectional view of an ultrasonic sensor according to an embodiment of the invention. 4 is a cross-sectional view of the ultrasonic sensor according to the embodiment of the present invention taken along line IV-IV in FIG.
  • the ultrasonic sensor 1 of this embodiment includes a case 10 and a piezoelectric element 20. As shown in FIGS. 1 to 4, the ultrasonic sensor 1 of this embodiment includes a case 10 and a piezoelectric element 20. As shown in FIGS. 1 to 4, the ultrasonic sensor 1 of this embodiment includes a case 10 and a piezoelectric element 20. As shown in FIGS. 1 to 4, the ultrasonic sensor 1 of this embodiment includes a case 10 and a piezoelectric element 20. As shown in FIGS.
  • the case 10 has a cylindrical shape with a bottom, and has a bottom portion 11 and a peripheral wall portion 15 as shown in FIGS.
  • the peripheral wall portion 15 extends from the bottom portion 11 along the axial direction Z of the central axis C of the bottom portion 11 perpendicular to the bottom portion 11 .
  • the bottom portion 11 has a circular outer shape when viewed from the axial direction Z.
  • the bottom portion 11 has a central portion 112 and an outer peripheral portion 113 surrounding the central portion 112 when the ultrasonic sensor 1 is viewed from the bottom portion 11 side.
  • the center of the central portion 112 is located on the central axis C of the bottom portion 11 when viewed from the axial direction Z.
  • the shape of the central portion 112 when viewed from the axial direction Z is not particularly limited, in the present embodiment, the central portion 112 has a square-shaped outer shape with rounded corners.
  • the central portion 112 When viewed from the axial direction Z, the central portion 112 has a rectangular outer shape with rounded corners. More specifically, central portion 112 has a pair of short sides of the rounded rectangular shape each having a semicircular shape.
  • the central portion 112 has a longitudinal direction X and a lateral direction Y when viewed from the axial direction Z.
  • the longitudinal direction X of the central portion 112 is the direction along the long sides of the central portion 112 .
  • a lateral direction Y of the central portion 112 is a direction perpendicular to the longitudinal direction X and along the short sides of the central portion 112 .
  • the inner peripheral edge of the outer peripheral portion 113 When viewed from the axial direction Z, the inner peripheral edge of the outer peripheral portion 113 is positioned along the outer peripheral edge of the central portion 112 . When viewed from the axial direction Z, the outer peripheral edge of the outer peripheral portion 113 constitutes the outer peripheral edge of the bottom portion 11 .
  • the surface facing the outside of the case 10 and the surface facing the inside of the case 10 are both positioned perpendicular to the axial direction Z.
  • a surface of the outer peripheral portion 113 facing the outside of the case 10 is positioned perpendicular to the axial direction Z.
  • the surface facing the outside of the case 10 is recessed at the central portion 112 .
  • the case 10 is made of a conductive material such as aluminum or aluminum alloy. Note that the case 10 may be made of an insulating material.
  • the piezoelectric element 20 is arranged on the bottom portion 11 inside the case 10. As shown in FIGS. Specifically, the piezoelectric element 20 is arranged on the central portion 112 .
  • the bottom portion 11 has an arrangement surface 119 on which the piezoelectric element 20 is arranged.
  • the piezoelectric element 20 is arranged on a placement surface 119 that is the base surface of the case 10 .
  • the piezoelectric element 20 is bonded to the central portion 112 with an adhesive such as epoxy resin. As shown in FIG. 2, the center of the piezoelectric element 20 is preferably positioned on the central axis C when viewed from the axial direction Z. As shown in FIG.
  • the configuration of the piezoelectric element 20 is not particularly limited.
  • the piezoelectric element 20 includes a piezoelectric body made of piezoelectric ceramic such as lead zirconate titanate (PZT), and a pair of electrodes sandwiching the piezoelectric body from both sides in the axial direction Z. may be
  • PZT lead zirconate titanate
  • the peripheral wall portion 15 extends along the axial direction Z from the outer peripheral portion 113 of the bottom portion 11 . As shown in FIGS. 1, 2 and 4, the peripheral wall 15 has an open end 150 opposite the bottom 11 .
  • a convex portion 161 (first convex portion) and a convex portion 162 (second convex portion) are provided on the open end portion 150 .
  • the convex portions 161 and the convex portions 162 are provided at different positions in the circumferential direction of the peripheral wall portion 15 and extend along the axial direction Z of the central axis C. As shown in FIG.
  • the open end portion 150 includes a flat portion 181 (first flat portion) having an end surface 1811 parallel to the placement surface 119 and a flat portion 182 (second flat portion) having an end surface 1821 parallel to the placement surface 119 . is further provided.
  • a convex portion 161, a flat portion 181, a convex portion 162, and a flat portion 182 are provided in this order.
  • a convex portion 161, a flat portion 181, a convex portion 162, and a flat portion 182 are provided in this order counterclockwise.
  • a concave portion 171 (first recess) is provided in the open end portion 150.
  • a recessed portion 172 (second recessed portion) is provided between the projected portion 161 and the flat portion 182 and is recessed toward the bottom portion 11 with respect to the projected portion 161 and the flat portion 182. .
  • a concave portion 173 ( a third recess) is provided at the open end 150.
  • a recess 174 (fourth recess) is provided between the protrusion 162 and the flat portion 182 and is recessed toward the bottom portion 11 with respect to the protrusion 162 and the flat portion 182. .
  • the height of the protrusion 161 (specifically, the tip of the protrusion 161) from the placement surface 119, the height of the protrusion 162 (specifically, the tip of the protrusion 162) from the placement surface 119, and the end surface 1811 of the flat portion 181. is the same as the height of the end face 1821 of the flat portion 182 from the placement surface 119 .
  • the “height from the placement surface 119” means the distance (the distance in the axial direction Z) from the placement surface 119 (more specifically, the virtual plane including the placement surface 119).
  • the convex portion 161 is formed by forming the concave portions 171 and 172 . It can also be said that the convex portion 162 is formed by forming the concave portions 173 and 174 .
  • the depth from the end face 1811 of the flat portion 181 of the recess 171, the depth from the end face 1821 of the flat portion 182 of the recess 172, and the depth from the end face 1811 of the flat portion 181 of the recess 173 and the depth of the recess 174 from the end surface 1821 of the flat portion 182 are the same.
  • the convex portion 161 and the convex portion 162 are provided so as to face each other across the central axis C at the open end portion 150 .
  • the peripheral wall portion 15 includes a pair of thick portions 211 and 212 facing each other and a pair of thin portions facing each other in directions different from the pair of thick portions 211 and 212 by 90 degrees. 221, 222.
  • the convex portion 161 is provided on one of the pair of thin portions 221 and 222 (specifically, the thin portion 221).
  • the convex portion 162 is provided on the other of the pair of thin portions 221 and 222 (specifically, the thin portion 222).
  • FIG. 5 is a block diagram showing the configuration of the ultrasound system of this embodiment.
  • the ultrasonic system 1000 includes an ultrasonic sensor 1 having a piezoelectric element 20 and a control device 900 .
  • the control device 900 is electrically connected to the piezoelectric element 20 .
  • the control device 900 is configured to apply pulse voltages of various frequencies to the piezoelectric element 20 .
  • the control device 900 is configured to be able to transmit pulse signals of various frequencies to the piezoelectric element 20 .
  • the control device 900 is configured to be able to receive the voltage generated in the piezoelectric element 20 by the vibration of the bottom portion 11 as a signal.
  • the control device 900 is typically arranged outside the case 10 .
  • the control device 900 controls the piezoelectric element 20 and the piezoelectric element 20 by means of a conductive member composed of, for example, an FPC (Flexible Printed Circuits) having a resin sheet and wiring, and two wiring sections connected to the FPC. electrically connected.
  • the conductive member is, for example, inserted from the outside of case 10 into the opening formed by open end 150 and arranged inside case 10 .
  • the control device 900 may be electrically connected to the piezoelectric element 20 by a lead wire.
  • the ultrasonic sensor 1 may further include a filling member and a sound absorbing material.
  • the filling member is made of silicone foam, for example, and filled inside the case 10 .
  • the filling member is arranged so that when the bottom portion 11 of the case 10 resonates at the resonance frequency, unwanted vibrations due to a different frequency can be damped.
  • the sound absorbing material is provided on the side opposite to the bottom portion 11 side of the piezoelectric element 20 . The sound absorbing material absorbs ultrasonic waves transmitted inside the case 10 when the ultrasonic waves are transmitted from the bottom portion 11 to the outside of the case 10 .
  • a method of transmitting and receiving ultrasound using the ultrasound system 1000 will be described.
  • a pulse voltage is applied from the control device 900 to the piezoelectric element 20 as shown in FIG. This causes the piezoelectric element 20 to vibrate.
  • the piezoelectric element 20 vibrates, mainly the central portion 112 of the bottom portion 11 connected to the piezoelectric element 20 vibrates. Thereby, ultrasonic waves can be transmitted from the bottom portion 11 to the outside of the case 10 .
  • the ultrasonic waves that hit mainly the central portion 112 of the bottom portion 11 from the outside of the case 10 vibrate mainly the central portion 112 of the bottom portion 11.
  • a voltage is generated in the piezoelectric element 20 by vibrating mainly the central portion 112 of the bottom portion 11 .
  • the control device 900 receives the voltage developed across the piezoelectric element 20 as a signal. In this manner, ultrasonic waves can be received using the ultrasonic sensor 1 .
  • the ultrasonic sensor 1 can be used as a device for measuring the distance to an object by reflecting the transmitted ultrasonic waves from an object located outside and receiving the reflected ultrasonic waves.
  • the case 10 of the ultrasonic sensor 1 can vibrate in at least two vibration modes. Since the ultrasonic sensor 1 includes the two convex portions 161 and 162, the bottom portion 11 can be vibrated at mutually different resonance frequencies in the two vibration modes. An example in which deformation of the case 10 of the ultrasonic sensor 1 in the two vibration modes is verified by experiments will be described below.
  • the ultrasonic sensor of the embodiment For the ultrasonic sensor of the embodiment, a simulation analysis was performed on how the case deformed during vibration in each of the above two vibration modes. Simulation analysis was performed by resonance analysis (modal analysis) using the finite element method.
  • the case of the ultrasonic sensor of the example has the same configuration as that of the ultrasonic sensor 1 according to the present embodiment.
  • the diameter of the bottom portion 11 (d1 in FIG. 3) when viewed from the axial direction Z is 15.5 mm, and the height of the case 10 along the axial direction Z ( 4 d2) is 9.0 mm
  • the circumferential width of the protrusions 161 and 162 is 2.0 mm
  • the circumferential width of the recesses 171 to 174 is 2.0 mm
  • the depth from the end surfaces 1811 and 1821 of the concave portions 171 to 174 was 2.0 mm.
  • FIG. 6 is a bottom view showing by simulation one state when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the first vibration mode.
  • FIG. 7 is a side view showing by simulation one state when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the first vibration mode.
  • FIG. 8 is a bottom view showing, by simulation, one state when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the second vibration mode.
  • FIG. 9 is a side view showing by simulation one state when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the second vibration mode.
  • the case of the ultrasonic sensor is shown as a contour diagram in which each part of the case is color-coded so that it becomes closer to white as the amount of deformation from the initial state increases. Further, in FIGS. 6 to 9, the ultrasonic sensors of the examples are denoted by the same reference numerals as the ultrasonic sensor 1 of the present embodiment.
  • each of the projections 161 and 162 is inclined toward the central axis C (see FIG. 1) when the axis C is curved in a convex shape toward one side (negative direction) of the axial direction Z.
  • the case 10 vibrated. Specifically, the case 10 vibrates so that each of the projections 161 and 162 is inclined in a direction in which the distance from the central axis C decreases from the root (base end) of each of them toward the tip. did.
  • the frequency of the pulse voltage at this time was 43.75 kHz.
  • the pulse voltage applied in the first vibration mode differs only in frequency from the pulse voltage applied in the first vibration mode so that the case 10 vibrates in the second vibration mode.
  • the piezoelectric element 20 each of the convex portions 161 and 162 is separated from the central axis C by The case 10 vibrated so as to tilt away.
  • the case 10 vibrates such that each of the projections 161 and 162 is inclined in a direction in which the distance from the central axis C increases from the root to the tip.
  • the frequency of the pulse voltage at this time was 50.54 kHz.
  • the bottom portion 11 in the second vibration mode, is deformed in substantially the same manner as in the first vibration mode, and the center axis C is deformed. It oscillated in direction Z. Therefore, in the ultrasonic sensor of the embodiment, the bottom part 11 can vibrate at two different resonance frequencies with substantially the same vibration intensity, and the ultrasonic sensor can transmit and receive ultrasonic waves with two different frequencies. all right.
  • the convex portions 161 and the convex portions 162 are provided at different positions in the circumferential direction of the peripheral wall portion 15, and extend along the axial direction Z of the central axis C. ing.
  • each of the convex portions 161 and 162 has a central axis C when the bottom portion 11 vibrates at the frequency of the first vibration mode.
  • the axial direction Z in this example, the negative direction of the axial direction Z
  • it is inclined in a direction approaching the central axis C.
  • Each of the convex portion 161 and the convex portion 162 has the bottom portion 11 positioned on the one side of the central axis C in the axial direction Z (in this example, in the negative direction of the axial direction Z) when vibrating at the frequency of the second vibration mode. ), it is inclined away from the central axis C.
  • the ultrasonic waves with the frequency of the second vibration mode can be handled in the same manner as the ultrasonic waves transmitted and received with the frequency of the first vibration mode. That is, the ultrasonic sensor 1 can transmit and receive two ultrasonic signals with different frequencies.
  • the protrusions 161 and 162 are provided at the open end 150 so as to extend along the axial direction Z of the central axis C, so that the piezoelectric element 20 is positioned on the bottom 11 inside the case 10 . can be easily attached to
  • the ultrasonic sensor 1 has a directivity of ultrasonic waves that can be transmitted and received when the case 10 vibrates in the first vibration mode, and a directivity of ultrasonic waves that can be transmitted and received when the case 10 vibrates in the second vibration mode. are configured to be significantly different from each other.
  • the ultrasonic system 1000 can determine the height of the object from the ground or the like by using the first vibration mode and the second vibration mode. By using the first vibration mode and the second vibration mode, the ultrasound system 1000 can improve time-series resolution for distance measurement.
  • the ultrasonic sensor 1 is preferably configured so that the frequency of the first vibration mode and the frequency of the second vibration mode are close to each other. Since these are close to each other, the bandwidth of the driving frequency of the ultrasonic sensor 1 can be widened.
  • the projections 161 and 162 are provided to face each other across the central axis C at the open end 150. As shown in FIG. As a result, the shape of the bottom portion 11 in a deformed state during vibration at the frequency of the second vibration mode becomes closer to the shape of the bottom portion 11 in a deformed state during vibration at the frequency of the first vibration mode. . As a result, it is possible to further increase the vibration intensity when vibrating in the second vibration mode.
  • the ultrasonic sensor 1 has four recesses 171 to 174 as described above. Therefore, it becomes easier to secure the length of the projections 161 and 162 in the axial direction Z. As shown in FIG.
  • the height of each of the projections 161 and 162 from the placement surface 119 and the height of each of the end surfaces 1811 and 1821 of the flat portion 181 from the placement surface 119 are the same. Therefore, the projections 161 and 162 do not protrude from the end surfaces 1811 and 1821 in the direction opposite to the bottom portion 11 . Therefore, the convex portions 161 and 162 are protected by the flat portions 181 and 182.
  • the projections 161 and 162 are formed simply by providing four recesses 171 to 174 (four cutouts) at the end having a flat end surface with respect to the placement surface 119. can do.
  • the depth of the recesses 171 and 173 from the end surface 1811 of the flat portion 181 and the depth of the recesses 172 and 174 from the end surface 1821 of the flat portion 182 are the same. According to such a configuration, by making the sizes of the protrusions 161 and 162 the same, the degree of inclination of the protrusions 161 and 162 in each vibration mode can be made substantially the same. Also, it is possible to reduce the number of parameters when designing the ultrasonic sensor 1 .
  • the convex portions 161 and 162 are provided on the thin portions 221 and 222. Therefore, the convex portions 161 and 162 are more likely to be inclined than when the convex portions 161 and 162 are provided on the thick portions 211 and 212 . That is, the convex portions 161 and 162 are easily bent. Therefore, the two vibration modes described above are likely to occur.
  • FIG. 10 is a perspective view of the ultrasonic sensor 1A viewed from the side opposite to the bottom side.
  • FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 10 of the ultrasonic sensor 1A.
  • the ultrasonic sensor 1A includes a case 10A instead of the case 10.
  • the ultrasonic sensor 1A has a peripheral wall portion 15A.
  • the peripheral wall portion 15A has an open end portion 150A on the side opposite to the bottom portion 11 .
  • the ultrasonic sensor 1A includes a convex portion 161A and a convex portion 162A. Also, the ultrasonic sensor 1A does not have the four concave portions 171-174. That is, there are concave portions between the convex portion 161A and the flat portion 181A, between the convex portion 161A and the flat portion 182A, between the convex portion 162A and the flat portion 181A, and between the convex portion 162A and the flat portion 182A. Not provided.
  • the ultrasonic sensor 1A includes a flat portion 181A and a flat portion 182A.
  • the ultrasonic sensor 1A has the convex portion 161A, the flat portion 181A, the convex portion 162A, and the flat portion 182A provided in this order at the open end portion 150 without interposing the concave portion.
  • the flat portion 181A has an end surface 1812 parallel to the placement surface 119.
  • the flat portion 182A has an end surface 1822 parallel to the placement surface 119. As shown in FIG.
  • a convex portion 161A (first convex portion) and a convex portion 162A (second convex portion) each extending along the axial direction Z of the central axis C are provided at different positions in the circumferential direction of the peripheral wall portion 15A.
  • a convex portion) is provided.
  • the convex portions 161A and 162A protrude from the end surfaces 1812 and 1822 to the side opposite to the placement surface 119.
  • the heights of the protrusions 161A and 162A (more specifically, the tips of the protrusions 161A and 162A) from the arrangement surface 119 are higher than the heights of the end surfaces 1812 and 1822 from the arrangement surface 119 .
  • the ultrasonic waves with the frequency of the second vibration mode can be handled in the same manner as the ultrasonic waves transmitted and received with the frequency of the first vibration mode. That is, the ultrasonic sensor 1 can transmit and receive two ultrasonic signals having different frequencies.
  • the piezoelectric element 20 is positioned on the bottom 11 inside the case 10A. can be easily attached to

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  • Transducers For Ultrasonic Waves (AREA)

Abstract

This ultrasonic sensor (1) comprises: a case (10) having a bottomed cylinder shape and including a bottom part (11) and a circumferential wall part (15) that extends from the bottom part (11) along an axial direction (Z) of a central axis (C) of the bottom part (11) which intersects with the bottom part (11); and a piezoelectric element (20) disposed on the bottom part (11) in the case (10). Protruding parts (161, 162) that each extend along the axial direction (Z) are provided to an opening end part (150) of the circumferential wall part (15) on the opposite side from the bottom part (11), in positions that differ from each other in the circumferential direction of the circumferential wall part (15) Each of the protruding parts (161, 162) is such that: during oscillation at a frequency of a first oscillation mode, when the bottom part (11) has curved in a protrusion shape to one direction side in the axial direction (Z), the protruding parts (161, 162) slope in a direction approaching the central axis (C); and during oscillation at a frequency of a second oscillation mode, when the bottom part (11) has curved in a protrusion shape to the one direction side in the axial direction (Z), the protruding parts (161, 162) slope in a direction separating from the central axis (C).

Description

超音波センサultrasonic sensor
　本開示は、超音波センサに関する。 The present disclosure relates to ultrasonic sensors.
　超音波センサの構成を開示した文献として、たとえば、米国特許第９３８３４４３号明細書（特許文献１）が挙げられる。特許文献１に記載された超音波センサは、ハウジングと、トランスデューサ素子と、少なくとも１つの質量要素とを備える。 For example, US Pat. No. 9,383,443 (Patent Document 1) is cited as a document disclosing the configuration of an ultrasonic sensor. The ultrasonic sensor described in US Pat. No. 5,900,005 comprises a housing, a transducer element and at least one mass element.
　ハウジングは、側壁部と、振動板として構成されているベース面とを有している。トランスデューサ素子は、超音波振動を発生および検出するために、ベース面に配置されている。 The housing has side walls and a base surface configured as a diaphragm. Transducer elements are positioned on the base surface for generating and detecting ultrasonic vibrations.
　少なくとも１つの質量要素は、ベース面に配置されている。少なくとも１つの質量要素は、振動板上の少なくとも１つの質量要素によって及ぼされる力およびトルクの少なくとも１つが、振動周波数の上昇に伴って増加するように配置されている。少なくとも１つの質量要素は、ベース面の中央に配置されている。少なくとも１つの質量要素は、振動板の３次振動モードが振動板の１次振動モードに近づくように、振動板の３次振動モードを変化させるインピーダンスを有している。 At least one mass element is arranged on the base surface. The at least one mass element is arranged such that at least one of force and torque exerted by the at least one mass element on the diaphragm increases with increasing vibration frequency. At least one mass element is centrally located on the base surface. At least one mass element has an impedance that changes the tertiary mode of vibration of the diaphragm such that the tertiary mode of vibration of the diaphragm approaches the primary mode of vibration of the diaphragm.
米国特許第９３８３４４３号明細書U.S. Pat. No. 9,383,443
　特許文献１に記載された超音波センサにおいては、少なくとも１つの質量要素によって、２つの振動モードに対応するように、周波数の異なる２つの超音波信号を送受信できる。 In the ultrasonic sensor described in Patent Document 1, at least one mass element can transmit and receive two ultrasonic signals with different frequencies so as to correspond to two vibration modes.
　しかしながら、特許文献１に記載された超音波センサにおいては、少なくとも１つの質量要素がハウジングのベース面に配置されているため、トランスデューサ素子をハウジングのベース面に取り付けることが難しくなる。 However, in the ultrasonic sensor described in Patent Document 1, since at least one mass element is arranged on the base surface of the housing, it becomes difficult to attach the transducer element to the base surface of the housing.
　本開示は上記の問題点に鑑みてなされたものであり、周波数の異なる２つの超音波信号を送受信可能であって、圧電素子を底部に取り付け容易な超音波センサを提供することを目的とする。 The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide an ultrasonic sensor capable of transmitting and receiving two ultrasonic signals having different frequencies and having a piezoelectric element attached to the bottom thereof. .
　本開示に基づく超音波センサは、底部と、底部に直交する底部の中心軸の軸方向に沿って底部から延びる周壁部とを含む、有底筒状のケースと、ケースの内部において底部上に配置された圧電素子とを備える。周壁部は、底部とは反対側に開口端部を有する。開口端部には、周壁部の周方向における互いに異なる位置に、各々が軸方向に沿って延びる第１の凸部と第２の凸部とが設けられている。第１の凸部と第２の凸部との各々は、第１の振動モードの周波数での振動時において底部が軸方向の一方側に凸状に湾曲したとき、中心軸に近づく向きに傾斜する。第１の凸部と第２の凸部との各々は、第２の振動モードの周波数での振動時において底部が軸方向の一方側に凸状に湾曲したとき、中心軸から離れる向きに傾斜する。 An ultrasonic sensor based on the present disclosure includes a bottomed cylindrical case including a bottom, a peripheral wall extending from the bottom along the axial direction of the central axis of the bottom perpendicular to the bottom, and a bottom inside the case on the bottom. and an arranged piezoelectric element. The peripheral wall has an open end opposite the bottom. The open end is provided with a first projection and a second projection, each extending along the axial direction, at different positions in the circumferential direction of the peripheral wall. Each of the first convex portion and the second convex portion is inclined in a direction approaching the central axis when the bottom portion is convexly curved to one side in the axial direction during vibration at the frequency of the first vibration mode. do. Each of the first convex portion and the second convex portion is inclined away from the central axis when the bottom portion is convexly curved to one side in the axial direction during vibration at the frequency of the second vibration mode. do.
　本開示によれば、周波数の異なる２つの超音波信号を送受信可能であって、圧電素子を底部に取り付け容易な超音波センサを提供できる。 According to the present disclosure, it is possible to provide an ultrasonic sensor capable of transmitting and receiving two ultrasonic signals with different frequencies and having a piezoelectric element easily attached to the bottom.
本発明の実施形態の超音波センサを底部側とは反対側から見た斜視図である。1 is a perspective view of an ultrasonic sensor according to an embodiment of the present invention, viewed from the side opposite to the bottom side; FIG. 本発明の実施形態の超音波センサを底部側とは反対側から見た平面図である。FIG. 2 is a plan view of the ultrasonic sensor of the embodiment of the present invention viewed from the side opposite to the bottom side; 本発明の実施形態の超音波センサを底部側から見た底面図である。It is the bottom view which looked at the ultrasonic sensor of embodiment of this invention from the bottom part side. 本発明の実施形態の超音波センサの断面図である。1 is a cross-sectional view of an ultrasonic sensor according to an embodiment of the invention; FIG. 本発明の実施形態の超音波システムの構成を示すブロック図である。1 is a block diagram showing the configuration of an ultrasound system according to an embodiment of the present invention; FIG. 実施例の超音波センサのケースが、第１の振動モードの周波数で振動しているときの一状態を、シミュレーションにより示した底面図である。FIG. 10 is a bottom view showing one state by simulation when the case of the ultrasonic sensor of the example is vibrating at the frequency of the first vibration mode. 実施例の超音波センサのケースが、第１の振動モードの周波数で振動しているときの一状態を、シミュレーションにより示した側面図である。FIG. 4 is a side view showing one state by simulation when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the first vibration mode. 実施例の超音波センサのケースが、第２の振動モードの周波数で振動しているときの一状態を、シミュレーションにより示した底面図である。FIG. 10 is a bottom view showing one state by simulation when the case of the ultrasonic sensor of the example is vibrating at the frequency of the second vibration mode. 実施例の超音波センサのケースが、第２の振動モードの周波数で振動しているときの一状態を、シミュレーションにより示した側面図である。FIG. 10 is a side view showing a state by simulation when the case of the ultrasonic sensor of the embodiment is vibrating at the frequency of the second vibration mode. 本発明の実施形態の変形例である超音波センサを底部側とは反対側から見た斜視図である。FIG. 11 is a perspective view of an ultrasonic sensor that is a modification of the embodiment of the present invention, viewed from the side opposite to the bottom side. 本発明の実施形態の変形例である超音波センサの図１０におけるXI-XI線矢視断面図である。FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 10 of an ultrasonic sensor that is a modification of the embodiment of the present invention;
　以下、本発明の各実施形態に係る超音波センサについて図を参照して説明する。以下の実施形態の説明においては、図中の同一または相当部分には同一符号を付して、その説明は繰り返さない。 An ultrasonic sensor according to each embodiment of the present invention will be described below with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.
　図１は、本発明の実施形態の超音波センサを底部側とは反対側から見た斜視図である。図２は、本発明の実施形態の超音波センサを底部側とは反対側から見た平面図である。図３は、本発明の実施形態の超音波センサを底部側から見た底面図である。図４は、本発明の実施形態の超音波センサの断面図である。なお、図４は、本発明の実施形態の超音波センサの図２におけるIV-IV線矢視断面図である。 FIG. 1 is a perspective view of an ultrasonic sensor according to an embodiment of the present invention, viewed from the side opposite to the bottom side. FIG. 2 is a plan view of the ultrasonic sensor of the embodiment of the present invention viewed from the side opposite to the bottom side. FIG. 3 is a bottom view of the ultrasonic sensor of the embodiment of the present invention viewed from the bottom side. FIG. 4 is a cross-sectional view of an ultrasonic sensor according to an embodiment of the invention. 4 is a cross-sectional view of the ultrasonic sensor according to the embodiment of the present invention taken along line IV-IV in FIG.
　図１から図４に示すように、本実施形態の超音波センサ１は、ケース１０と、圧電素子２０とを備えている。 As shown in FIGS. 1 to 4, the ultrasonic sensor 1 of this embodiment includes a case 10 and a piezoelectric element 20. As shown in FIGS.
　ケース１０は、有底筒状であって、図１および図４に示すように、底部１１と、周壁部１５とを有している。周壁部１５は、底部１１に直交する底部１１の中心軸Ｃの軸方向Ｚに沿って底部１１から延びている。 The case 10 has a cylindrical shape with a bottom, and has a bottom portion 11 and a peripheral wall portion 15 as shown in FIGS. The peripheral wall portion 15 extends from the bottom portion 11 along the axial direction Z of the central axis C of the bottom portion 11 perpendicular to the bottom portion 11 .
　図３に示すように、底部１１は、軸方向Ｚから見て円形状の外形を有している。底部１１は、超音波センサ１を底部１１側から見て、中央部１１２と、中央部１１２を取り囲む外周部１１３とを有している。 As shown in FIG. 3, the bottom portion 11 has a circular outer shape when viewed from the axial direction Z. The bottom portion 11 has a central portion 112 and an outer peripheral portion 113 surrounding the central portion 112 when the ultrasonic sensor 1 is viewed from the bottom portion 11 side.
　軸方向Ｚから見て、中央部１１２の中心は、底部１１の中心軸Ｃ上に位置している。軸方向Ｚから見て、中央部１１２の形状は特に限定されないが、本実施形態においては、中央部１１２は、角丸方形状の外形を有している。 The center of the central portion 112 is located on the central axis C of the bottom portion 11 when viewed from the axial direction Z. Although the shape of the central portion 112 when viewed from the axial direction Z is not particularly limited, in the present embodiment, the central portion 112 has a square-shaped outer shape with rounded corners.
　軸方向Ｚから見て、中央部１１２は、具体的には角丸長方形状の外形を有している。より具体的には、中央部１１２は、当該角丸長方形状の一対の短辺の各々が半円状である。 When viewed from the axial direction Z, the central portion 112 has a rectangular outer shape with rounded corners. More specifically, central portion 112 has a pair of short sides of the rounded rectangular shape each having a semicircular shape.
　中央部１１２は、軸方向Ｚから見て、長手方向Ｘと、短手方向Ｙとを有している。中央部１１２の長手方向Ｘは、中央部１１２の長辺に沿う方向である。中央部１１２の短手方向Ｙは、長手方向Ｘと直交し、中央部１１２の短辺に沿う方向である。 The central portion 112 has a longitudinal direction X and a lateral direction Y when viewed from the axial direction Z. The longitudinal direction X of the central portion 112 is the direction along the long sides of the central portion 112 . A lateral direction Y of the central portion 112 is a direction perpendicular to the longitudinal direction X and along the short sides of the central portion 112 .
　軸方向Ｚから見て、外周部１１３の内周縁は、中央部１１２の外周縁に沿うように位置している。軸方向Ｚから見て、外周部１１３の外周縁は、底部１１の外周縁を構成する。 When viewed from the axial direction Z, the inner peripheral edge of the outer peripheral portion 113 is positioned along the outer peripheral edge of the central portion 112 . When viewed from the axial direction Z, the outer peripheral edge of the outer peripheral portion 113 constitutes the outer peripheral edge of the bottom portion 11 .
　図１から図４に示すように、中央部１１２において、ケース１０の外側に向く面、および、ケース１０の内側に向く面は、いずれも軸方向Ｚに直交するように位置している。外周部１１３においてケース１０の外側に向く面は、軸方向Ｚに直交するように位置している。底部１１において、ケース１０の外側に向く面は、中央部１１２で凹んでいる。 As shown in FIGS. 1 to 4, in the central portion 112, the surface facing the outside of the case 10 and the surface facing the inside of the case 10 are both positioned perpendicular to the axial direction Z. As shown in FIGS. A surface of the outer peripheral portion 113 facing the outside of the case 10 is positioned perpendicular to the axial direction Z. As shown in FIG. At the bottom portion 11 , the surface facing the outside of the case 10 is recessed at the central portion 112 .
　ケース１０は、アルミニウムまたはアルミニウム合金などの導電性材料で構成されている。なお、ケース１０は、絶縁性材料で構成されていてもよい。 The case 10 is made of a conductive material such as aluminum or aluminum alloy. Note that the case 10 may be made of an insulating material.
　図１、図２、および図４に示すように、圧電素子２０は、ケース１０の内部において底部１１上に配置されている。具体的には、圧電素子２０は、中央部１１２上に配置されている。底部１１は、圧電素子２０が配置される配置面１１９を有する。圧電素子２０は、ケース１０のベース面である配置面１１９に配置されている。 As shown in FIGS. 1, 2, and 4, the piezoelectric element 20 is arranged on the bottom portion 11 inside the case 10. As shown in FIGS. Specifically, the piezoelectric element 20 is arranged on the central portion 112 . The bottom portion 11 has an arrangement surface 119 on which the piezoelectric element 20 is arranged. The piezoelectric element 20 is arranged on a placement surface 119 that is the base surface of the case 10 .
　圧電素子２０は、たとえばエポキシ樹脂などの接着剤により中央部１１２に接合されている。図２に示すように、軸方向Ｚから見て、圧電素子２０の中心は、上記中心軸Ｃ上に位置していることが好ましい。 The piezoelectric element 20 is bonded to the central portion 112 with an adhesive such as epoxy resin. As shown in FIG. 2, the center of the piezoelectric element 20 is preferably positioned on the central axis C when viewed from the axial direction Z. As shown in FIG.
　圧電素子２０の構成は、特に限定されない。圧電素子２０は、たとえば、チタン酸ジルコン酸鉛(ＰＺＴ)などの圧電セラミックスにより構成された圧電体と、この圧電体を軸方向Ｚの両側から挟み込むように配置された１対の電極とを備えていてもよい。 The configuration of the piezoelectric element 20 is not particularly limited. The piezoelectric element 20 includes a piezoelectric body made of piezoelectric ceramic such as lead zirconate titanate (PZT), and a pair of electrodes sandwiching the piezoelectric body from both sides in the axial direction Z. may be
　図３および図４に示すように、周壁部１５は、底部１１の外周部１１３から軸方向Ｚに沿って延びている。図１、図２、および図４に示すように、周壁部１５は、底部１１とは反対側に開口端部１５０を有している。 As shown in FIGS. 3 and 4, the peripheral wall portion 15 extends along the axial direction Z from the outer peripheral portion 113 of the bottom portion 11 . As shown in FIGS. 1, 2 and 4, the peripheral wall 15 has an open end 150 opposite the bottom 11 .
　開口端部１５０には、凸部１６１（第１の凸部）と凸部１６２（第２の凸部）とが設けられている。凸部１６１と凸部１６２とは、周壁部１５の周方向における互いに異なる位置に設けられており、各々が中心軸Ｃの軸方向Ｚに沿って延びている。 A convex portion 161 (first convex portion) and a convex portion 162 (second convex portion) are provided on the open end portion 150 . The convex portions 161 and the convex portions 162 are provided at different positions in the circumferential direction of the peripheral wall portion 15 and extend along the axial direction Z of the central axis C. As shown in FIG.
　開口端部１５０には、配置面１１９に平行な端面１８１１を有する平坦部１８１（第１の平坦部）と、配置面１１９に平行な端面１８２１を有する平坦部１８２（第２の平坦部）とがさらに設けられている。 The open end portion 150 includes a flat portion 181 (first flat portion) having an end surface 1811 parallel to the placement surface 119 and a flat portion 182 (second flat portion) having an end surface 1821 parallel to the placement surface 119 . is further provided.
　開口端部１５０においては、凸部１６１と、平坦部１８１と、凸部１６２と、平坦部１８２とが、この順に設けられている。図２に示すように、ＸＹ平面において、凸部１６１と、平坦部１８１と、凸部１６２と、平坦部１８２とが、この順に反時計回りに設けられている。 In the open end portion 150, a convex portion 161, a flat portion 181, a convex portion 162, and a flat portion 182 are provided in this order. As shown in FIG. 2, on the XY plane, a convex portion 161, a flat portion 181, a convex portion 162, and a flat portion 182 are provided in this order counterclockwise.
　図１および図２に示すように、開口端部１５０においては、凸部１６１と平坦部１８１との間に、凸部１６１および平坦部１８１とに対して底部１１の方向に凹んだ凹部１７１（第１の凹部）が設けられている。開口端部１５０においては、凸部１６１と平坦部１８２との間に、凸部１６１および平坦部１８２とに対して底部１１の方向に凹んだ凹部１７２（第２の凹部）が設けられている。 As shown in FIGS. 1 and 2, in the open end portion 150, a concave portion 171 ( first recess) is provided. In the open end portion 150, a recessed portion 172 (second recessed portion) is provided between the projected portion 161 and the flat portion 182 and is recessed toward the bottom portion 11 with respect to the projected portion 161 and the flat portion 182. .
　図１および図２に示すように、開口端部１５０においては、凸部１６２と平坦部１８１との間に、凸部１６２および平坦部１８１とに対して底部１１の方向に凹んだ凹部１７３（第３の凹部）が設けられている。開口端部１５０においては、凸部１６２と平坦部１８２との間に、凸部１６２および平坦部１８２とに対して底部１１の方向に凹んだ凹部１７４（第４の凹部）が設けられている。 As shown in FIGS. 1 and 2, at the open end 150, between the convex portion 162 and the flat portion 181, a concave portion 173 ( a third recess) is provided. In the open end portion 150, a recess 174 (fourth recess) is provided between the protrusion 162 and the flat portion 182 and is recessed toward the bottom portion 11 with respect to the protrusion 162 and the flat portion 182. .
　凸部１６１（詳しくは、凸部１６１の先端）の配置面１１９からの高さと、凸部１６２（詳しくは、凸部１６２の先端）の配置面１１９からの高さと、平坦部１８１の端面１８１１の配置面１１９からの高さと、平坦部１８２の端面１８２１の配置面１１９からの高さとは、同じである。なお、「配置面１１９からの高さ」とは、配置面１１９（詳しくは、配置面１１９を含む仮想平面）との間の距離（軸方向Ｚの向きの距離）を意味する。 The height of the protrusion 161 (specifically, the tip of the protrusion 161) from the placement surface 119, the height of the protrusion 162 (specifically, the tip of the protrusion 162) from the placement surface 119, and the end surface 1811 of the flat portion 181. is the same as the height of the end face 1821 of the flat portion 182 from the placement surface 119 . The “height from the placement surface 119” means the distance (the distance in the axial direction Z) from the placement surface 119 (more specifically, the virtual plane including the placement surface 119).
　なお、本例では、凹部１７１，１７２が形成されていることにより凸部１６１が形成されているとも言える。凹部１７３，１７４が形成されていることにより凸部１６２が形成されているとも言える。 In this example, it can also be said that the convex portion 161 is formed by forming the concave portions 171 and 172 . It can also be said that the convex portion 162 is formed by forming the concave portions 173 and 174 .
　図１および図４に示すように、凹部１７１の平坦部１８１の端面１８１１からの深さと、凹部１７２の平坦部１８２の端面１８２１からの深さと、凹部１７３の平坦部１８１の端面１８１１からの深さと、凹部１７４の平坦部１８２の端面１８２１からの深さとは、同じである。 1 and 4, the depth from the end face 1811 of the flat portion 181 of the recess 171, the depth from the end face 1821 of the flat portion 182 of the recess 172, and the depth from the end face 1811 of the flat portion 181 of the recess 173 and the depth of the recess 174 from the end surface 1821 of the flat portion 182 are the same.
　凸部１６１と凸部１６２とは、開口端部１５０において、中心軸Ｃを挟んで互いに対向するように設けられている。図１～図３に示すように、周壁部１５は、互いに対向する一対の厚肉部２１１，２１２と、一対の厚肉部２１１，２１２とは９０度異なる向きで互いに対向する一対の薄肉部２２１，２２２とを有している。 The convex portion 161 and the convex portion 162 are provided so as to face each other across the central axis C at the open end portion 150 . As shown in FIGS. 1 to 3, the peripheral wall portion 15 includes a pair of thick portions 211 and 212 facing each other and a pair of thin portions facing each other in directions different from the pair of thick portions 211 and 212 by 90 degrees. 221, 222.
　凸部１６１は、一対の薄肉部２２１，２２２のうちの一方（具体的には薄肉部２２１）に設けられている。凸部１６２は、一対の薄肉部２２１，２２２のうちの他方（具体的には薄肉部２２２）に設けられている。 The convex portion 161 is provided on one of the pair of thin portions 221 and 222 (specifically, the thin portion 221). The convex portion 162 is provided on the other of the pair of thin portions 221 and 222 (specifically, the thin portion 222).
　図５は、本実施形態の超音波システムの構成を示すブロック図である。図５に示すように、超音波システム１０００は、圧電素子２０を有する超音波センサ１と、制御装置９００とを備えている。 FIG. 5 is a block diagram showing the configuration of the ultrasound system of this embodiment. As shown in FIG. 5, the ultrasonic system 1000 includes an ultrasonic sensor 1 having a piezoelectric element 20 and a control device 900 .
　制御装置９００は、圧電素子２０と電気的に接続されている。制御装置９００は、様々な周波数のパルス電圧を圧電素子２０に印加可能に構成されている。換言すれば、制御装置９００は、様々な周波数のパルス信号を圧電素子２０に送信可能に構成されている。制御装置９００は、底部１１の振動により圧電素子２０に生じた電圧を信号として受信可能に構成されている。 The control device 900 is electrically connected to the piezoelectric element 20 . The control device 900 is configured to apply pulse voltages of various frequencies to the piezoelectric element 20 . In other words, the control device 900 is configured to be able to transmit pulse signals of various frequencies to the piezoelectric element 20 . The control device 900 is configured to be able to receive the voltage generated in the piezoelectric element 20 by the vibration of the bottom portion 11 as a signal.
　制御装置９００は、典型的にはケース１０の外側に配置される。制御装置９００は、たとえば、樹脂シートと配線とを有するＦＰＣ(Flexible　Printed　Circuits、フレキシブルプリント回路基板)と、当該ＦＰＣに接続された２つの配線部とで構成された導電部材により、圧電素子２０と電気的に接続される。当該導電部材は、たとえば、ケース１０の外部から、開口端部１５０によって形成された開口に挿入されて、ケース１０の内部に配置される。なお、制御装置９００は、リード線により、圧電素子２０と電気的に接続されていてもよい。 The control device 900 is typically arranged outside the case 10 . The control device 900 controls the piezoelectric element 20 and the piezoelectric element 20 by means of a conductive member composed of, for example, an FPC (Flexible Printed Circuits) having a resin sheet and wiring, and two wiring sections connected to the FPC. electrically connected. The conductive member is, for example, inserted from the outside of case 10 into the opening formed by open end 150 and arranged inside case 10 . Note that the control device 900 may be electrically connected to the piezoelectric element 20 by a lead wire.
　超音波センサ１は、充填部材と吸音材をさらに備えていてもよい。充填部材は、たとえばシリコーン発泡体で構成されて、ケース１０内部に充填される。充填部材は、ケース１０の底部１１が共振周波数で共振したときに、これとは異なる周波数による不要な振動を減衰可能に配置される。吸音材は、圧電素子２０の底部１１側とは反対側に設けられる。吸音材は、底部１１からケース１０の外部に超音波を発信する際に、ケース１０の内部に発信する超音波を吸収する。 The ultrasonic sensor 1 may further include a filling member and a sound absorbing material. The filling member is made of silicone foam, for example, and filled inside the case 10 . The filling member is arranged so that when the bottom portion 11 of the case 10 resonates at the resonance frequency, unwanted vibrations due to a different frequency can be damped. The sound absorbing material is provided on the side opposite to the bottom portion 11 side of the piezoelectric element 20 . The sound absorbing material absorbs ultrasonic waves transmitted inside the case 10 when the ultrasonic waves are transmitted from the bottom portion 11 to the outside of the case 10 .
　超音波システム１０００を用いた、超音波の送信および受信の方法について説明する。まず、超音波センサ１を用いて超音波を送信する際には、図５に示すように、制御装置９００から圧電素子２０にパルス電圧を印加する。これにより、圧電素子２０が振動する。圧電素子２０が振動することにより、圧電素子２０に接続された底部１１の主に中央部１１２が振動する。これにより、底部１１から、ケース１０の外部に、超音波を発信することができる。 A method of transmitting and receiving ultrasound using the ultrasound system 1000 will be described. First, when transmitting ultrasonic waves using the ultrasonic sensor 1, a pulse voltage is applied from the control device 900 to the piezoelectric element 20 as shown in FIG. This causes the piezoelectric element 20 to vibrate. When the piezoelectric element 20 vibrates, mainly the central portion 112 of the bottom portion 11 connected to the piezoelectric element 20 vibrates. Thereby, ultrasonic waves can be transmitted from the bottom portion 11 to the outside of the case 10 .
　超音波センサ１を用いて超音波を受信する際には、ケース１０の外部から底部１１の主に中央部１１２に当たった超音波によって、底部１１の主に中央部１１２が振動する。底部１１の主に中央部１１２が振動することにより、圧電素子２０に電圧が生じる。制御装置９００が圧電素子２０に生じた電圧を信号として受信する。このようにして、超音波センサ１を用いて超音波を受信できる。 When ultrasonic waves are received using the ultrasonic sensor 1, the ultrasonic waves that hit mainly the central portion 112 of the bottom portion 11 from the outside of the case 10 vibrate mainly the central portion 112 of the bottom portion 11. A voltage is generated in the piezoelectric element 20 by vibrating mainly the central portion 112 of the bottom portion 11 . The control device 900 receives the voltage developed across the piezoelectric element 20 as a signal. In this manner, ultrasonic waves can be received using the ultrasonic sensor 1 .
　超音波センサ１は、たとえば、送信した超音波が外部に位置する物体によって反射して、その反射した超音波を受信することで、当該物体との距離測定装置として使用することができる。 For example, the ultrasonic sensor 1 can be used as a device for measuring the distance to an object by reflecting the transmitted ultrasonic waves from an object located outside and receiving the reflected ultrasonic waves.
　超音波センサ１のケース１０は、少なくとも２つの振動モードで振動することができる。超音波センサ１は、２つの凸部１６１，１６２を備えることにより、当該２つの振動モードにおいては、それぞれ、互いに異なる共振周波数で、底部１１を振動させることができる。以下、当該２つの振動モードにおける超音波センサ１のケース１０の変形の様子について実験により検証した実施例について説明する。 The case 10 of the ultrasonic sensor 1 can vibrate in at least two vibration modes. Since the ultrasonic sensor 1 includes the two convex portions 161 and 162, the bottom portion 11 can be vibrated at mutually different resonance frequencies in the two vibration modes. An example in which deformation of the case 10 of the ultrasonic sensor 1 in the two vibration modes is verified by experiments will be described below.
　実施例の超音波センサについて、上記２つの振動モードの各々の振動時におけるケースの変形の様子をシミュレーション解析した。シミュレーション解析は、有限要素法を用いた共振解析(モーダル解析)により行なった。実施例の超音波センサのケースは、本実施形態に係る超音波センサ１と同様の構成とした。 For the ultrasonic sensor of the embodiment, a simulation analysis was performed on how the case deformed during vibration in each of the above two vibration modes. Simulation analysis was performed by resonance analysis (modal analysis) using the finite element method. The case of the ultrasonic sensor of the example has the same configuration as that of the ultrasonic sensor 1 according to the present embodiment.
　具体的には、実施例の超音波センサにおいては、軸方向Ｚから見たときの底部１１の直径（図３のｄ１）を１５．５ｍｍ、軸方向Ｚに沿ったケース１０の高さ（図４のｄ２）を９．０ｍｍ、凸部１６１，１６２の周方向の幅（図４のｄ５参照）を２．０ｍｍ、凹部１７１～１７４の周方向の幅（図４のｄ４，ｄ６参照）を２．０ｍｍ、凹部１７１～１７４の端面１８１１，１８２１からの深さ（図４のｄ３参照）を２．０ｍｍとした。 Specifically, in the ultrasonic sensor of the embodiment, the diameter of the bottom portion 11 (d1 in FIG. 3) when viewed from the axial direction Z is 15.5 mm, and the height of the case 10 along the axial direction Z ( 4 d2) is 9.0 mm, the circumferential width of the protrusions 161 and 162 (see d5 in FIG. 4) is 2.0 mm, and the circumferential width of the recesses 171 to 174 (see d4 and d6 in FIG. 4) is 2.0 mm, and the depth from the end surfaces 1811 and 1821 of the concave portions 171 to 174 (see d3 in FIG. 4) was 2.0 mm.
　図６は、実施例の超音波センサのケースが、第１の振動モードの周波数で振動しているときの一状態を、シミュレーションにより示した底面図である。図７は、実施例の超音波センサのケースが、第１の振動モードの周波数で振動しているときの一状態を、シミュレーションにより示した側面図である。 FIG. 6 is a bottom view showing by simulation one state when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the first vibration mode. FIG. 7 is a side view showing by simulation one state when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the first vibration mode.
　図８は、実施例の超音波センサのケースが、第２の振動モードの周波数で振動しているときの一状態を、シミュレーションにより示した底面図である。図９は、実施例の超音波センサのケースが、第２の振動モードの周波数で振動しているときの一状態を、シミュレーションにより示した側面図である。 FIG. 8 is a bottom view showing, by simulation, one state when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the second vibration mode. FIG. 9 is a side view showing by simulation one state when the case of the ultrasonic sensor of the embodiment vibrates at the frequency of the second vibration mode.
　図６から図９においては、ケースの各部位について初期状態からの変形量が大きくなるに従って白色に近くなるように色分けされたコンター図として、超音波センサのケースを示している。また、図６～図９においては、実施例の超音波センサについて、本実施形態の超音波センサ１と同様の符号を付している。 In FIGS. 6 to 9, the case of the ultrasonic sensor is shown as a contour diagram in which each part of the case is color-coded so that it becomes closer to white as the amount of deformation from the initial state increases. Further, in FIGS. 6 to 9, the ultrasonic sensors of the examples are denoted by the same reference numerals as the ultrasonic sensor 1 of the present embodiment.
　図６および図７に示すように、実施例の超音波センサは、ケース１０が第１の振動モード（基本振動モード）で振動するように圧電素子２０にパルス電圧を印加すると、底部１１が中心軸Ｃの軸方向Ｚの一方側（負の向き）に凸状に湾曲したときに、凸部１６１と凸部１６２との各々は中心軸Ｃ（図１参照）に近づく向きに傾斜するように、ケース１０が振動した。詳しくは、凸部１６１と凸部１６２との各々が、当該各々の根元（基端）から先端に向かうに連れて中心軸Ｃとの距離が短くなる向きに傾斜するように、ケース１０が振動した。このときのパルス電圧の周波数は４３．７５ｋＨｚであった。 As shown in FIGS. 6 and 7, in the ultrasonic sensor of the embodiment, when a pulse voltage is applied to the piezoelectric element 20 so that the case 10 vibrates in a first vibration mode (fundamental vibration mode), the bottom 11 is centered. Each of the projections 161 and 162 is inclined toward the central axis C (see FIG. 1) when the axis C is curved in a convex shape toward one side (negative direction) of the axial direction Z. , the case 10 vibrated. Specifically, the case 10 vibrates so that each of the projections 161 and 162 is inclined in a direction in which the distance from the central axis C decreases from the root (base end) of each of them toward the tip. did. The frequency of the pulse voltage at this time was 43.75 kHz.
　一方、図８および図９に示すように、実施例の超音波センサにおいて、ケース１０が第２の振動モードで振動するように、第１の振動モードで印加したパルス電圧と周波数のみ異なるパルス電圧を圧電素子２０に印加すると、底部１１が中心軸Ｃの軸方向Ｚの一方側（負の向き）に凸状に湾曲したときに、凸部１６１と凸部１６２との各々は中心軸Ｃから離れる向きに傾斜するように、ケース１０が振動した。詳しくは、凸部１６１と凸部１６２との各々が、当該各々の根元から先端に向かうに連れて中心軸Ｃとの距離が長くなる向きに傾斜するように、ケース１０が振動した。このときのパルス電圧の周波数は５０．５４ｋＨｚであった。 On the other hand, as shown in FIGS. 8 and 9, in the ultrasonic sensor of the embodiment, the pulse voltage applied in the first vibration mode differs only in frequency from the pulse voltage applied in the first vibration mode so that the case 10 vibrates in the second vibration mode. is applied to the piezoelectric element 20, each of the convex portions 161 and 162 is separated from the central axis C by The case 10 vibrated so as to tilt away. Specifically, the case 10 vibrates such that each of the projections 161 and 162 is inclined in a direction in which the distance from the central axis C increases from the root to the tip. The frequency of the pulse voltage at this time was 50.54 kHz.
　すなわち、図６～図９に示すように、実施例の超音波センサにおいては、第２の振動モードにおいて、底部１１が第１の振動モードのときと略同様に変形して中心軸Ｃの軸方向Ｚに振動した。このため、実施例の超音波センサにおいては、底部１１が、２つの異なる共振周波数において、略同様の振動強度で振動することができ、超音波センサが２つの周波数の異なる超音波を送受信できることがわかった。 That is, as shown in FIGS. 6 to 9, in the ultrasonic sensor of the embodiment, in the second vibration mode, the bottom portion 11 is deformed in substantially the same manner as in the first vibration mode, and the center axis C is deformed. It oscillated in direction Z. Therefore, in the ultrasonic sensor of the embodiment, the bottom part 11 can vibrate at two different resonance frequencies with substantially the same vibration intensity, and the ultrasonic sensor can transmit and receive ultrasonic waves with two different frequencies. all right.
　本実施形態の超音波センサ１においては、凸部１６１と凸部１６２とは、周壁部１５の周方向における互いに異なる位置に設けられており、各々が中心軸Ｃの軸方向Ｚに沿って延びている。上記の実証実験（実施例）で示すように、超音波センサ１においては、凸部１６１と凸部１６２との各々は、第１の振動モードの周波数での振動時において底部１１が中心軸Ｃの軸方向Ｚの一方側（本例では、軸方向Ｚの負の向き）に凸状に湾曲したとき、中心軸Ｃに近づく向きに傾斜する。凸部１６１と凸部１６２との各々は、第２の振動モードの周波数での振動時において底部１１が中心軸Ｃの軸方向Ｚの上記一方側（本例では、軸方向Ｚの負の向き）に凸状に湾曲したとき、中心軸Ｃから離れる向きに傾斜する。 In the ultrasonic sensor 1 of the present embodiment, the convex portions 161 and the convex portions 162 are provided at different positions in the circumferential direction of the peripheral wall portion 15, and extend along the axial direction Z of the central axis C. ing. As shown in the above-described demonstration experiment (example), in the ultrasonic sensor 1, each of the convex portions 161 and 162 has a central axis C when the bottom portion 11 vibrates at the frequency of the first vibration mode. When curved in a convex shape in one side of the axial direction Z (in this example, the negative direction of the axial direction Z), it is inclined in a direction approaching the central axis C. Each of the convex portion 161 and the convex portion 162 has the bottom portion 11 positioned on the one side of the central axis C in the axial direction Z (in this example, in the negative direction of the axial direction Z) when vibrating at the frequency of the second vibration mode. ), it is inclined away from the central axis C.
　これにより、本実施形態の超音波センサ１においては、第２の振動モードの周波数の超音波を、第１の振動モードの周波数で送受信される超音波と同様に取り扱うことができる。すなわち、超音波センサ１は、周波数の異なる２つの超音波信号を送受信可能である。 Accordingly, in the ultrasonic sensor 1 of the present embodiment, the ultrasonic waves with the frequency of the second vibration mode can be handled in the same manner as the ultrasonic waves transmitted and received with the frequency of the first vibration mode. That is, the ultrasonic sensor 1 can transmit and receive two ultrasonic signals with different frequencies.
　凸部１６１と凸部１６２とは、開口端部１５０において、各々が中心軸Ｃの軸方向Ｚに沿って延びるように設けられているため、圧電素子２０を、ケース１０の内部において底部１１上に容易に取り付けることができる。 The protrusions 161 and 162 are provided at the open end 150 so as to extend along the axial direction Z of the central axis C, so that the piezoelectric element 20 is positioned on the bottom 11 inside the case 10 . can be easily attached to
　超音波センサ１は、第１の振動モードでケース１０が振動するときに送受信可能な超音波の指向性と、第２の振動モードでケース１０が振動するときに送受信可能な超音波の指向性とが、互いに大きく異なるように構成されていることが好ましい。 The ultrasonic sensor 1 has a directivity of ultrasonic waves that can be transmitted and received when the case 10 vibrates in the first vibration mode, and a directivity of ultrasonic waves that can be transmitted and received when the case 10 vibrates in the second vibration mode. are configured to be significantly different from each other.
　これらの指向性が互いに大きく異なっていることにより、たとえば、超音波センサ１の外部に位置する物体に向かって２種類の周波数の超音波を送信し、かつ、当該物体で反射したこれらの超音波を受信することにより、当該物体までの距離および当該物体の高さを検知することができる。なお、周波数が低いほど、指向性は広くなる。 Since these directivities are greatly different from each other, for example, ultrasonic waves of two frequencies are transmitted toward an object located outside the ultrasonic sensor 1, and these ultrasonic waves reflected by the object is received, the distance to the object and the height of the object can be detected. Note that the lower the frequency, the wider the directivity.
　超音波システム１０００は、第１の振動モードと第２の振動モードとを利用することにより、上記物体の地面等からの高さを判別できる。超音波システム１０００は、第１の振動モードと第２の振動モードとを利用することにより、距離の測定に関して時系列分解能を向上させることができる。 The ultrasonic system 1000 can determine the height of the object from the ground or the like by using the first vibration mode and the second vibration mode. By using the first vibration mode and the second vibration mode, the ultrasound system 1000 can improve time-series resolution for distance measurement.
　超音波センサ１は、第１の振動モードの周波数および第２の振動モードの周波数は、互いに近接するように構成されていることが好ましい。これらが互いに近接していることで、超音波センサ１の駆動周波数の帯域幅を広くすることができる。 The ultrasonic sensor 1 is preferably configured so that the frequency of the first vibration mode and the frequency of the second vibration mode are close to each other. Since these are close to each other, the bandwidth of the driving frequency of the ultrasonic sensor 1 can be widened.
　超音波センサ１では、凸部１６１と凸部１６２とは、開口端部１５０において、中心軸Ｃを挟んで互いに対向するように設けられている。これにより、第２の振動モードの周波数での振動時において変形した状態の底部１１の形状が、第１の振動モードの周波数での振動時において変形した状態の底部１１の形状に、より近くなる。ひいては、第２の振動モードで振動したときの振動強度を、より大きくすることができる。 In the ultrasonic sensor 1, the projections 161 and 162 are provided to face each other across the central axis C at the open end 150. As shown in FIG. As a result, the shape of the bottom portion 11 in a deformed state during vibration at the frequency of the second vibration mode becomes closer to the shape of the bottom portion 11 in a deformed state during vibration at the frequency of the first vibration mode. . As a result, it is possible to further increase the vibration intensity when vibrating in the second vibration mode.
　超音波センサ１は、上述したように、４つの凹部１７１～１７４を備える。このため、凸部１６１，１６２の軸方向Ｚの長さを確保しやすくなる。 The ultrasonic sensor 1 has four recesses 171 to 174 as described above. Therefore, it becomes easier to secure the length of the projections 161 and 162 in the axial direction Z. As shown in FIG.
　上述したように、凸部１６１，１６２の各々の配置面１１９からの高さと、平坦部１８１の端面１８１１，１８２１の各々の配置面１１９からの高さとは、同じである。このため、凸部１６１，１６２が、端面１８１１，１８２１から底部１１とは反対側の向きに突き出ることはない。よって、凸部１６１，１６２は平坦部１８１，１８２によって保護される。 As described above, the height of each of the projections 161 and 162 from the placement surface 119 and the height of each of the end surfaces 1811 and 1821 of the flat portion 181 from the placement surface 119 are the same. Therefore, the projections 161 and 162 do not protrude from the end surfaces 1811 and 1821 in the direction opposite to the bottom portion 11 . Therefore, the convex portions 161 and 162 are protected by the flat portions 181 and 182.
　また、超音波センサ１の製造工程において、配置面１１９に対して平坦な端面を有する端部に、４つの凹部１７１～１７４（４つの切り欠き）を設けるだけで、凸部１６１，１６２を形成することができる。 Further, in the manufacturing process of the ultrasonic sensor 1, the projections 161 and 162 are formed simply by providing four recesses 171 to 174 (four cutouts) at the end having a flat end surface with respect to the placement surface 119. can do.
　上述したように、凹部１７１，１７３の平坦部１８１の端面１８１１からの深さと、凹部１７２，１７４の平坦部１８２の端面１８２１からの深さとは、同じである。このような構成によれば、凸部１６１と凸部１６２との大きさを同じにすることによって、各振動モードでの凸部１６１および凸部１６２の傾き具合を略同じにすることができる。また、超音波センサ１の設計時において、パラメータの数を減らすことも可能となる。 As described above, the depth of the recesses 171 and 173 from the end surface 1811 of the flat portion 181 and the depth of the recesses 172 and 174 from the end surface 1821 of the flat portion 182 are the same. According to such a configuration, by making the sizes of the protrusions 161 and 162 the same, the degree of inclination of the protrusions 161 and 162 in each vibration mode can be made substantially the same. Also, it is possible to reduce the number of parameters when designing the ultrasonic sensor 1 .
　上述したように、凸部１６１，１６２は、薄肉部２２１，２２２に設けられている。それゆえ、凸部１６１，１６２が厚肉部２１１，２１２に設けられているときよりも、凸部１６１，１６２は傾斜しやすくなる。すなわち、凸部１６１，１６２が撓みやすくなる。したがって、上述した２つの振動モードが生じやすくなる。 As described above, the convex portions 161 and 162 are provided on the thin portions 221 and 222. Therefore, the convex portions 161 and 162 are more likely to be inclined than when the convex portions 161 and 162 are provided on the thick portions 211 and 212 . That is, the convex portions 161 and 162 are easily bent. Therefore, the two vibration modes described above are likely to occur.
　＜変形例＞
　本発明の実施形態の超音波センサ１の変形例である超音波センサ１Ａについて説明する。 <Modification>
An ultrasonic sensor 1A, which is a modification of the ultrasonic sensor 1 of the embodiment of the present invention, will be described.
　図１０は、超音波センサ１Ａを底部側とは反対側から見た斜視図である。図１１は、超音波センサ１Ａの図１０におけるXI-XI線矢視断面図である。 FIG. 10 is a perspective view of the ultrasonic sensor 1A viewed from the side opposite to the bottom side. FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 10 of the ultrasonic sensor 1A.
　図１０および図１１に示すように、超音波センサ１Ａは、ケース１０の代わりにケース１０Ａを備える。超音波センサ１Ａは、周壁部１５Ａを備える。周壁部１５Ａは、底部１１とは反対側に開口端部１５０Ａを備える。 As shown in FIGS. 10 and 11, the ultrasonic sensor 1A includes a case 10A instead of the case 10. The ultrasonic sensor 1A has a peripheral wall portion 15A. The peripheral wall portion 15A has an open end portion 150A on the side opposite to the bottom portion 11 .
　超音波センサ１Ａは、凸部１６１Ａと、凸部１６２Ａとを備える。また、超音波センサ１Ａは、４つの凹部１７１～１７４を有していない。すなわち、凸部１６１Ａと平坦部１８１Ａとの間、凸部１６１Ａと平坦部１８２Ａとの間、凸部１６２Ａと平坦部１８１Ａとの間、凸部１６２Ａと平坦部１８２Ａとの間には、凹部が設けられていない。超音波センサ１Ａは、平坦部１８１Ａと、平坦部１８２Ａとを備える。 The ultrasonic sensor 1A includes a convex portion 161A and a convex portion 162A. Also, the ultrasonic sensor 1A does not have the four concave portions 171-174. That is, there are concave portions between the convex portion 161A and the flat portion 181A, between the convex portion 161A and the flat portion 182A, between the convex portion 162A and the flat portion 181A, and between the convex portion 162A and the flat portion 182A. Not provided. The ultrasonic sensor 1A includes a flat portion 181A and a flat portion 182A.
　このように、超音波センサ１Ａは、開口端部１５０において、凹部を介することなく、凸部１６１Ａと、平坦部１８１Ａと、凸部１６２Ａと、平坦部１８２Ａとが、この順に設けられている。 In this manner, the ultrasonic sensor 1A has the convex portion 161A, the flat portion 181A, the convex portion 162A, and the flat portion 182A provided in this order at the open end portion 150 without interposing the concave portion.
　平坦部１８１Ａは、配置面１１９に平行な端面１８１２を有する。平坦部１８２Ａは、配置面１１９に平行な端面１８２２を有する。 The flat portion 181A has an end surface 1812 parallel to the placement surface 119. The flat portion 182A has an end surface 1822 parallel to the placement surface 119. As shown in FIG.
　開口端部１５０Ａには、周壁部１５Ａの周方向における互いに異なる位置に、各々が中心軸Ｃの軸方向Ｚに沿って延びる凸部１６１Ａ（第１の凸部）と凸部１６２Ａ（第２の凸部）とが設けられている。 In the open end portion 150A, a convex portion 161A (first convex portion) and a convex portion 162A (second convex portion) each extending along the axial direction Z of the central axis C are provided at different positions in the circumferential direction of the peripheral wall portion 15A. A convex portion) is provided.
　凸部１６１Ａ，１６２Ａは、端面１８１２，１８２２から、配置面１１９とは反対側に突き出ている。凸部１６１Ａ，１６２Ａ（詳しくは、凸部１６１Ａ，１６２Ａの先端）の配置面１１９からの高さは、端面１８１２，１８２２の配置面１１９からの高さよりも高い。 The convex portions 161A and 162A protrude from the end surfaces 1812 and 1822 to the side opposite to the placement surface 119. The heights of the protrusions 161A and 162A (more specifically, the tips of the protrusions 161A and 162A) from the arrangement surface 119 are higher than the heights of the end surfaces 1812 and 1822 from the arrangement surface 119 .
　このような構成であっても、超音波センサ１と同様に、第２の振動モードの周波数の超音波を、第１の振動モードの周波数で送受信される超音波と同様に取り扱うことができる。すなわち、超音波センサ１は、周波数の異なる２つの超音波信号を送受信可能となる。 Even with such a configuration, similarly to the ultrasonic sensor 1, the ultrasonic waves with the frequency of the second vibration mode can be handled in the same manner as the ultrasonic waves transmitted and received with the frequency of the first vibration mode. That is, the ultrasonic sensor 1 can transmit and receive two ultrasonic signals having different frequencies.
　凸部１６１Ａと凸部１６２Ａとは、開口端部１５０Ａにおいて、各々が中心軸Ｃの軸方向Ｚに沿って延びるように設けられているため、圧電素子２０を、ケース１０Ａの内部において底部１１上に容易に取り付けることができる。 Since the protrusions 161A and 162A are provided at the opening end 150A so as to extend along the axial direction Z of the central axis C, the piezoelectric element 20 is positioned on the bottom 11 inside the case 10A. can be easily attached to
　今回開示された実施形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all changes within the scope and meaning equivalent to the scope of the claims.
　１，１Ａ　超音波センサ、１０，１０Ａ　ケース、１１　底部、１５，１５Ａ　周壁部、２０　圧電素子、１１２　中央部、１１３　外周部、１１９　配置面、１５０，１５０Ａ　開口端部、１６１，１６１Ａ，１６２，１６２Ａ　凸部、１７１，１７２，１７３，１７４　凹部、１８１，１８１Ａ，１８２，１８２Ａ　平坦部、２１１，２１２　厚肉部、１８１１，１８１２，１８２１，１８２２　端面、Ｃ　中心軸。 1, 1A Ultrasonic sensor, 10, 10A Case, 11 Bottom, 15, 15A Peripheral wall, 20 Piezoelectric element, 112 Central, 113 Peripheral, 119 Placement surface, 150, 150A Open end, 161, 161A, 162, 162A convex portions, 171, 172, 173, 174 concave portions, 181, 181A, 182, 182A flat portions, 211, 212 thick portions, 1811, 1812, 1821, 1822 end faces, C central axis.

Claims (6)

  1. 　底部と、前記底部に直交する前記底部の中心軸の軸方向に沿って前記底部から延びる周壁部とを含む、有底筒状のケースと、
    　前記ケースの内部において前記底部上に配置された圧電素子とを備え、
    　前記周壁部は、前記底部とは反対側に開口端部を有し、
    　前記開口端部には、前記周壁部の周方向における互いに異なる位置に、各々が前記軸方向に沿って延びる第１の凸部と第２の凸部とが設けられ、
    　前記第１の凸部と前記第２の凸部との各々は、
    　　第１の振動モードの周波数での振動時において前記底部が前記軸方向の一方側に凸状に湾曲したとき、前記中心軸に近づく向きに傾斜し、
    　　第２の振動モードの周波数での振動時において前記底部が前記軸方向の前記一方側に凸状に湾曲したとき、前記中心軸から離れる向きに傾斜する、超音波センサ。     a bottomed cylindrical case including a bottom and a peripheral wall extending from the bottom along the axial direction of the central axis of the bottom perpendicular to the bottom;
    a piezoelectric element disposed on the bottom inside the case,
    The peripheral wall has an open end opposite to the bottom,
    The opening end is provided with a first protrusion and a second protrusion each extending along the axial direction at different positions in the circumferential direction of the peripheral wall,
    Each of the first protrusion and the second protrusion is
    When the bottom portion is convexly curved toward one side in the axial direction during vibration at the frequency of the first vibration mode, the bottom portion is inclined toward the central axis,
    The ultrasonic sensor tilts away from the central axis when the bottom is convexly curved toward the one side in the axial direction during vibration at the frequency of the second vibration mode.
  2. 　前記底部は、前記圧電素子が配置される配置面を有し、
    　前記開口端部には、各々が前記配置面に平行な端面を有する第１の平坦部と第２の平坦部とが設けられ、
    　前記第１の凸部と前記第１の平坦部との間に、前記第１の凸部および前記第１の平坦部とに対して前記底部の方向に凹んだ第１の凹部が設けられ、
    　前記第１の凸部と前記第２の平坦部との間に、前記第１の凸部および前記第２の平坦部とに対して前記底部の方向に凹んだ第２の凹部が設けられ、
    　前記第２の凸部と前記第１の平坦部との間に、前記第２の凸部および前記第１の平坦部とに対して前記底部の方向に凹んだ第３の凹部が設けられ、
    　前記第２の凸部と前記第２の平坦部との間に、前記第２の凸部および前記第２の平坦部とに対して前記底部の方向に凹んだ第４の凹部が設けられている、請求項１に記載の超音波センサ。     The bottom portion has an arrangement surface on which the piezoelectric element is arranged,
    The opening end is provided with a first flat portion and a second flat portion, each having an end surface parallel to the arrangement surface,
    Between the first convex portion and the first flat portion, a first concave portion recessed toward the bottom portion with respect to the first convex portion and the first flat portion is provided,
    Between the first convex portion and the second flat portion, a second concave portion recessed toward the bottom portion with respect to the first convex portion and the second flat portion is provided,
    Between the second convex portion and the first flat portion, there is provided a third concave portion recessed in the direction of the bottom portion with respect to the second convex portion and the first flat portion,
    Between the second convex portion and the second flat portion, a fourth concave portion is provided that is concave toward the bottom portion with respect to the second convex portion and the second flat portion. 2. The ultrasonic sensor of claim 1, wherein a
  3. 　前記第１の凸部の前記配置面からの高さと、前記第２の凸部の前記配置面からの高さと、前記第１の平坦部の端面の前記配置面からの高さと、前記第２の平坦部の端面の前記配置面からの高さとは、同じである、請求項２に記載の超音波センサ。 The height of the first convex portion from the arrangement surface, the height of the second convex portion from the arrangement surface, the height of the end surface of the first flat portion from the arrangement surface, and the second 3. The ultrasonic sensor according to claim 2, wherein the height of the end surface of the flat portion of is the same from the placement surface.
  4. 　前記第１の凹部の前記第１の平坦部の端面からの深さと、前記第２の凹部の前記第２の平坦部の端面からの深さと、前記第３の凹部の前記第１の平坦部の端面からの深さと、前記第４の凹部の前記第２の平坦部の端面からの深さとは、同じである、請求項３に記載の超音波センサ。 The depth of the first recess from the end surface of the first flat portion, the depth of the second recess from the end surface of the second flat portion, and the first flat portion of the third recess 4. The ultrasonic sensor according to claim 3, wherein the depth from the end surface of the fourth recess and the depth from the end surface of the second flat portion of the fourth recess are the same.
  5. 　前記第１の凸部と前記第２の凸部とは、前記中心軸を挟んで互いに対向するように設けられている、請求項１から４のいずれか１項に記載の超音波センサ。 The ultrasonic sensor according to any one of claims 1 to 4, wherein the first convex portion and the second convex portion are provided so as to face each other with the central axis interposed therebetween.
  6. 　前記周壁部は、互いに対向する一対の厚肉部と、前記一対の厚肉部とは異なる向きで互いに対向する一対の薄肉部とを有し、
    　前記第１の凸部は、前記一対の薄肉部のうちの一方に設けられており、
    　前記第２の凸部は、前記一対の薄肉部のうちの他方に設けられている、請求項１から５のいずれか１項に記載の超音波センサ。     The peripheral wall portion has a pair of thick portions facing each other and a pair of thin portions facing each other in a direction different from that of the pair of thick portions,
    The first convex portion is provided on one of the pair of thin portions,
    The ultrasonic sensor according to any one of claims 1 to 5, wherein the second convex portion is provided on the other of the pair of thin portions.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003315443A (en) * 2002-04-25 2003-11-06 Nippon Soken Inc Ultrasonic sensor
WO2019131375A1 (en) * 2017-12-25 2019-07-04 株式会社ニフコ Sensor assembly and method for attaching same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003315443A (en) * 2002-04-25 2003-11-06 Nippon Soken Inc Ultrasonic sensor
WO2019131375A1 (en) * 2017-12-25 2019-07-04 株式会社ニフコ Sensor assembly and method for attaching same

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