JP5237786B2 - Ultrasonic transducer - Google Patents

Description

  The present invention relates to an ultrasonic transducer that transmits and receives an ultrasonic frequency band.

In an ultrasonic transducer according to a conventional embodiment, when this is embedded in a car bumper or the like and an obstacle around it is detected, the pulse transducer electric signal is input to the ultrasonic transducer to generate an ultrasonic wave. An ultrasonic signal corresponding to the input pulse burst electric signal is oscillated from the sonic transducer, and the oscillated ultrasonic signal is reflected by the obstacle after reaching the obstacle, and part of the ultrasonic signal is the same Return to the ultrasonic transducer. The ultrasonic transducer detects an obstacle by receiving the reflected signal.
FIG. 3 is a schematic longitudinal sectional view of an ultrasonic transducer and a schematic diagram of a bottomed cylindrical case and a piezoelectric element according to a conventional embodiment. In FIG. 3, the piezoelectric element 1 is fixed inside the bottomed cylindrical case 2 made of an aluminum material or the like to form a unimorph vibrator. The input / output leads 5a and the input / output leads 5b are taken out from the piezoelectric element 1 from the inner side surface of the bottomed cylindrical case 2 by soldering or the like. The piezoelectric element 1 and the bottomed cylindrical case 2 are electrically connected by a fixing surface. The input / output lead wires 5a and 5b are respectively soldered to the wire 6 of the connector 7 with the PVC coated wire. A sound absorbing material 3 made of a silicone foam or the like is installed on the upper surface of the piezoelectric element 1, and a sealing agent 8 made of an elastic material such as a silicone material or a urethane material is further filled into the bottomed cylindrical case 2.
FIG. 4 shows a schematic longitudinal sectional view of another ultrasonic transducer according to the conventional embodiment, a schematic diagram of a bottomed cylindrical case, and a piezoelectric element. In FIG. 4, a unimorph vibrator is formed by fixing the piezoelectric element 1 inside the bottom surface of a bottomed cylindrical case 2 made of an aluminum material or the like having an expanded bottom end in the longitudinal direction. The input / output leads 5a and the input / output leads 5b are taken out from the piezoelectric element 1 from the inner side surface of the bottomed cylindrical case 2 by soldering or the like. The piezoelectric element 1 and the bottomed cylindrical case 2 are electrically connected by a fixing surface. The input / output lead wires 5a and 5b are respectively soldered to the wire 6 of the connector 7 with the PVC coated wire. A sound absorbing material 3 made of a silicone foam or the like is installed on the upper surface of the piezoelectric element 1, and a sealing agent 8 made of a foamed elastic material such as a silicone material or a foaming urethane material is further placed inside the bottomed cylindrical case 2. Fill.
Conventionally, when detecting obstacles in the vicinity of a car installed in the car, the vertical directivity is narrower than the horizontal direction in order to suppress unnecessary reflection from the road surface. The shape is changed to a rectangular shape by changing the length. 3 and 4, the vibration of the bottom surface portion appears in a generally rectangular shape along the edge based on the center of the bottom surface, like the vibration node 9. In this way, the directivity depends on the vibration part length of the bottom surface, so it is difficult to increase the aspect ratio of the bottomed cylindrical case, especially for small ultrasonic transducers. It is difficult to enlarge.
JP 2006-340258 Tanikoshi Shinji “Ultrasound and its usage-Ultrasonic transducers and ultrasonic motors” Nikkan Kogyo Shimbun 1994

  In ultrasonic transducers that transmit and receive ultrasonic frequency bands, there is a limit to increasing the ratio of horizontal directivity and vertical directivity depending on the length of the bottomed cylindrical case. In ultrasonic transducers, reflections from the road surface are injured, limiting the use of vehicles and long-distance detection.

The ultrasonic transducer according to the conventional embodiment is an ultrasonic transducer that forms a unimorph vibrator by laminating piezoelectric elements of a bottomed cylindrical case and transmits / receives ultrasonic waves by the vibration of the unimorph vibrator. In this case, since the amplitude of the bottom end of the bottomed cylindrical case is lower than that of the center due to vibration braking from the periphery, it is difficult to increase the horizontal / vertical directivity ratio sufficiently. In the ultrasonic transducer according to the embodiment of the present invention, the vibration node is controlled to reduce the damping element at the end portion having a small amplitude to increase the amplitude, and the center portion has a larger amplitude than the end portion. Is suppressed. By narrowing the side wall in the longitudinal direction inside the bottom surface, the vibration node in the center is changed so that the amplitude distribution approaches the same on the entire vibration surface, so that the horizontal directivity is wide and the vertical directivity is It becomes narrower and increases the directivity ratio between the horizontal and vertical directions to suppress reflection from the road surface and enhance the detection in the horizontal direction.
Similarly, in an ultrasonic transducer that forms a unimorph vibrator by bonding piezoelectric elements of a cylindrical case with a bottom and transmits and receives ultrasonic waves by the vibration of the unimorph vibrator, the ultrasonic transducer according to the embodiment of the present invention is used. In sonic transducers, the longitudinal end side wall inside the bottom surface protrudes outward widely and the central side wall protrudes narrow, thereby changing the vibration node in the center and changing the amplitude of the entire vibration surface. By making the distributions close to the same, the horizontal directivity is wide and the vertical directivity is narrowed. Further, the horizontal and vertical directivity ratio is increased to suppress reflection from the road surface, thereby improving the horizontal detectability.

  In the ultrasonic transducer, the horizontal directivity is wide, the vertical directivity is narrowed, and the directivity ratio is increased, thereby suppressing reflection from the road surface and improving the horizontal detectability.

  When used in in-vehicle corner sensors, etc., it can be embedded in a bumper, etc. to suppress reflection from the road surface and realize stable obstacle detection from short to long distances.

FIG. 1 is a schematic sectional view of an ultrasonic transducer according to an embodiment of the present invention, a schematic diagram of a bottomed cylindrical case, and a piezoelectric element. In FIG. 1, a piezoelectric element 1 is fixed inside a bottom surface of a bottomed cylindrical case 2 made of an aluminum material or the like having a narrow bottom portion in the longitudinal direction to form a unimorph vibrator. The input / output lead 5a and the input / output lead 5b are taken out of the piezoelectric element 1 from the inner side surface of the bottomed cylindrical case 2 by soldering or the like. The piezoelectric element 1 and the bottomed cylindrical case 2 are electrically connected by a fixing surface. The input / output leads 5a and 5b are respectively soldered to the wire 6 of the connector 7 with the PVC coated wire. A sound absorbing material 3 made of a silicone foam or the like is installed on the upper surface of the piezoelectric element 1, and a sealing agent 8 made of an elastic material such as a silicone material or a urethane material is further filled into the bottomed cylindrical case 2.
FIG. 2 shows a schematic cross-sectional view of another ultrasonic transducer according to the embodiment of the present invention, a schematic diagram of a bottomed cylindrical case, and a piezoelectric element. In FIG. 2, the piezoelectric element 1 is fixed inside the bottom surface of the bottomed cylindrical case 2 made of an aluminum material or the like having a wide bottom surface shape in the longitudinal direction and a narrow central portion to form a unimorph vibrator. The input / output lead 5a and the input / output lead 5b are taken out of the piezoelectric element 1 from the inner side surface of the bottomed cylindrical case 2 by soldering or the like. The input / output leads 5a and 5b are respectively soldered to the wire 6 of the connector 7 with the PVC coated wire. A sound absorbing material 3 made of a silicone foam or the like is installed on the upper surface of the piezoelectric element 1, and a sealing agent 8 made of an elastic material such as a silicone material or a urethane material is further filled into the bottomed cylindrical case 2.
In the ultrasonic transducer according to the embodiment of the present invention, like the vibration node 10, the vibration node is controlled to reduce the damping element at the end portion having a small amplitude and to increase the amplitude. Also, the generation of a large amplitude is suppressed. In the ultrasonic transmitter / receiver according to the embodiment of the present invention, the horizontal directivity is wide, the vertical directivity can be narrowed, the horizontal / vertical directivity ratio is large, and it is unnecessary from the road surface when attaching to a car or the like. Since the reflection can be suppressed and the horizontal detection range can be widened, it is possible to provide an ultrasonic transducer that can stably detect obstacles even when installed at a low position or when long distance detection is required. .

  The present invention can be applied not only to a back sensor of a car but also to various fields where a drip-proof ultrasonic transducer is used.

Schematic of a bottomed cylindrical case according to an embodiment of the present invention Schematic of a bottomed cylindrical case according to an embodiment of the present invention Schematic of a bottomed cylindrical case according to a conventional embodiment Schematic of a bottomed cylindrical case according to a conventional embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Bottomed cylindrical case 3 Sound-absorbing material 4 Sealant made of elastic material 5a Input / output lead 5b Input / output lead
6 PVC coated wire 7 Connector with PVC coated wire 8 Sealant 9 Schematic diagram of vibration node according to conventional embodiment 10 Schematic diagram of vibration node according to embodiment of the present invention

Claims (2)

A bottomed cylindrical shape that is formed in a generally rectangular shape in an ultrasonic transducer that forms a unimorph vibrator by bonding a piezoelectric element inside the bottom of a bottomed cylindrical case and transmits and receives ultrasonic waves by the vibration of the unimorph vibrator. The inner cavity is formed by bending the inner side wall facing the center part inwardly so that the center of the longitudinal side of the bottom side of the inner cavity part of the case is bent inward. An ultrasonic transducer characterized in that the center width on the long side of the bottom surface is shorter than the end width on the long side of the bottom surface. A bottomed cylindrical shape that is formed in a generally rectangular shape in an ultrasonic transducer that forms a unimorph vibrator by bonding a piezoelectric element inside the bottom of a bottomed cylindrical case and transmits and receives ultrasonic waves by the vibration of the unimorph vibrator. The inner side wall facing the long side end is bent outwardly so that the vibration node at the end of the bottom side of the bottom surface of the inner cavity of the case is bent outward, 2. The ultrasonic transducer according to claim 1, wherein an end width of the longitudinal side of the bottom surface of the internal cavity is also longer than a central width of the longitudinal side of the bottom surface.

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