JP2008306315A - Ultrasonic wave echo transceiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein an ultrasonic wave transceiver using a conventional cylindrical case with a bottom is damaged with external stress and its sensor characteristics are deteriorated. <P>SOLUTION: In an ultrasonic wave transceiver, at least one layer of elastic high molecular material (silicon, urethane, or synthetic rubber, etc.) of Poisson's ratio 0.45 to 0.49 with a thickness of 0.1 mm or more and 1.5 mm or less is prepared, as coated films applied to a vibration plane of a cylindrical resin case with a bottom. The total thickness of coated films on the vibration plane is set to 1.6 mm or less to secure ultrasonic wave transmission/reception. Thereby, external stress can be eased, and deterioration in sensor characteristics can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic transducer that detects an obstacle or the like by transmitting and receiving an ultrasonic frequency band.

In the ultrasonic transducer according to the conventional embodiment, when an ultrasonic transducer is embedded in a vehicle bumper or the like and an obstacle around the vehicle is to be detected, pulse burst electrical is applied to the ultrasonic transducer. By inputting the signal, an ultrasonic signal corresponding to the input pulse burst electric signal is oscillated from the ultrasonic transducer, and the oscillated ultrasonic signal reaches the obstacle, and the ultrasonic signal hits the obstacle. Is reflected by the obstacle, and a part of the reflected ultrasonic signal returns to the same ultrasonic transducer. Ultrasonic transducers are used in back sensor systems that detect obstacles by receiving their reflected signals.
FIG. 4 is a schematic cross-sectional view of an ultrasonic transducer according to a conventional embodiment. (a) is a front view of an ultrasonic transducer | vibrator, (b) is a right view, (c) is a back view. This ultrasonic transducer is configured by filling a hollow housing with a filler, and FIG. 4 (d) shows a side cross-sectional view of the state where the filler is removed. The ultrasonic transducer 10 includes a piezoelectric element 12 in a conductive housing 11 made of aluminum. As shown in FIG. 1B, an internal space 13 is formed inside the housing 11, and the piezoelectric element 12 is attached to the inner surface of the vibration surface 11 a in the housing 11. And the resin-made film 14 is affixed on the outer surface of this vibration surface 11a so that the whole surface of this vibration surface 11a may be covered. The resin film 14 is a transparent film made of polyurethane, is formed in a circular shape, and an adhesive is applied to the back surface. The entire surface of the housing 11 is painted in a predetermined color (the same color as the vehicle bumper). Therefore, the surface of the vibration surface 11a looks the same color as the bumper of the vehicle through the transparent film 14. One end of a lead 15 is soldered to the piezoelectric element 12. The other end of the lead 15 is soldered to the inner side surface of the housing 11. Thereby, the vibration surface 11 a is vibrated at both ends of the piezoelectric element 12 through the housing 11. The internal space 13 of the housing 11 is filled with a filler such as silicon after the lead 15 is soldered.
Patent Publication JP 2005-308639 A Tanikoshi Shinji “Ultrasound and its usage-Ultrasonic transducers and ultrasonic motors” Nikkan Kogyo Shimbun 1994

  When installed in a car as a back sensor system in an obstacle detection device using an ultrasonic transducer, the ultrasonic transducer is damaged by external stress such as contact with pebbles and the transmission output efficiency of ultrasonic waves is reduced. This was a cause of prolonged reverberation time and deterioration of excitation response. In Japanese Patent Laid-Open Publication No. 2005-308639, a resin film is attached using an adhesive to make it difficult to corrode, but there is a problem that the film is peeled off due to secular change. Furthermore, although the film thickness is not specified, there is a problem that when the film thickness is increased, the ultrasonic vibration characteristics are affected and transmission / reception becomes impossible.

  A coating applied to the vibration surface of an ultrasonic transducer that forms a unimorph vibrator by laminating a piezoelectric element inside the bottom surface of a bottomed cylindrical case, and transmits and receives ultrasonic waves on the outer surface of the case. Of these, at least one layer of elastic polymer material (silicon, urethane, synthetic rubber, etc.) with a Poisson's ratio of 0.45 to 0.49 and a thickness of 0.1 mm to 1.5 mm is provided, but the total thickness of the coating applied to the vibration surface Is 1.6 mm or less to relieve external stress while ensuring ultrasonic transmission / reception characteristics. Resilient polymer materials (silicon, urethane, synthetic rubber, etc.) with a Poisson's ratio in the range of 0.45 to 0.49 have less vibration suppression and a high mechanical flaw prevention effect, but if the thickness is less than 0.1 mm If the flaw prevention effect is small and the total thickness of the coating applied to the vibration surface is greater than 1.6 mm, the influence on the ultrasonic vibration characteristics is large, and transmission / reception becomes difficult.

  The present invention has the advantages of relaxing external stress on the ultrasonic transducer and enhancing durability.

FIG. 1 is a schematic longitudinal sectional view of an ultrasonic transducer according to an embodiment of the present invention. In FIG. 1, a piezoelectric element 1 is bonded to the inside of the bottom surface of a bottomed cylindrical case 2 made of an aluminum material or the like with an adhesive 3 to constitute a unimorph vibrator. The input / output lead 5a from the piezoelectric element 1 and the opposite surface of the piezoelectric element 1 to the bottomed cylindrical case 2 and the adhesive surface side are soldered and the input / output lead 5b is removed from the bottomed cylindrical case 2 by soldering. The adhesive surface side of the piezoelectric element 1 with the bottomed cylindrical case 2 and the bottomed cylindrical case 2 are electrically connected, and the piezoelectric element 1 and the input / output leads 5a and 5b are electrically connected. Yes. A sound absorbing material 6 made of foamed silicon or the like is placed on the upper surface of the piezoelectric element 1, and a sealing agent 4 made of a silicon material or the like is filled into the bottomed cylindrical case 2 from above. The vibration surface of the bottomed resin case 2 is covered with a covering material 7 made of an elastic polymer material (silicon, urethane, synthetic rubber, etc.) having a Poisson's ratio of 0.45 to 0.49 and a thickness of 0.1 mm to 1.5 mm. To do.
FIG. 2 is a schematic longitudinal sectional view of an ultrasonic transducer according to another embodiment of the present invention. In FIG. 2, a piezoelectric element 1 is bonded to the inside of the bottom surface of a bottomed cylindrical case 2 made of an aluminum material or the like with an adhesive 3 to constitute a unimorph vibrator. The input / output lead 5a from the piezoelectric element 1 and the opposite surface of the piezoelectric element 1 to the bottomed cylindrical case 2 and the adhesive surface side are soldered and the input / output lead 5b is removed from the bottomed cylindrical case 2 by soldering. The adhesive surface side of the piezoelectric element 1 with the bottomed cylindrical case 2 and the bottomed cylindrical case 2 are electrically connected, and the piezoelectric element 1 and the input / output leads 5a and 5b are electrically connected. Yes. A sound absorbing material 6 made of foamed silicon or the like is placed on the upper surface of the piezoelectric element 1, and a sealing agent 4 made of a silicon material or the like is filled into the bottomed cylindrical case 2 from above. Covering the vibration surface of the bottomed resin case 2 with a coating material 8 such as electrodeposition coating as a base coating, and from there on, an elastic polymer material having a Poisson's ratio of 0.45 to 0.49 and a thickness of 0.1 mm to 1.5 mm It is covered with a covering material 7 made of (silicon, urethane, synthetic rubber, etc.). The total film thickness of the covering material 7 and the covering material 8 is 1.6 mm or less.
FIG. 3 is a schematic longitudinal sectional view of an ultrasonic transducer according to another embodiment of the present invention. In FIG. 3, a piezoelectric element 1 is bonded to the bottom surface of a bottomed cylindrical case 2 made of an aluminum material or the like with an adhesive 3 to constitute a unimorph vibrator. The input / output lead 5a from the piezoelectric element 1 and the opposite surface of the piezoelectric element 1 to the bottomed cylindrical case 2 and the adhesive surface side are soldered and the input / output lead 5b is removed from the bottomed cylindrical case 2 by soldering. The adhesive surface side of the piezoelectric element 1 with the bottomed cylindrical case 2 and the bottomed cylindrical case 2 are electrically connected, and the piezoelectric element 1 and the input / output leads 5a and 5b are electrically connected. Yes. A sound absorbing material 6 made of foamed silicon or the like is placed on the upper surface of the piezoelectric element 1, and a sealing agent 4 made of a silicon material or the like is filled into the bottomed cylindrical case 2 from above. Covering the vibration surface of the bottomed resin case 2 with a coating material 8 such as electrodeposition coating as a base coating, and from there on, an elastic polymer material having a Poisson's ratio of 0.45 to 0.49 and a thickness of 0.1 mm to 1.5 mm It is covered with a covering material 7 made of (silicon, urethane, synthetic rubber, etc.) and further covered with a covering material 9 made of an acrylic resin or the like for ensuring design properties. The total film thickness of the covering material 7, the covering material 8, and the covering material 9 is 1.6 mm or less.

  The present invention can be applied not only to a vehicle back sensor system but also to various fields in which a drip-proof ultrasonic transducer is used.

1 is a schematic longitudinal sectional view of an ultrasonic transducer according to an embodiment of the present invention. Schematic longitudinal sectional view of an ultrasonic transducer according to another embodiment of the present invention Schematic longitudinal sectional view of an ultrasonic transducer according to another embodiment of the present invention Schematic sectional view of an ultrasonic transducer according to a conventional embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Bottomed cylindrical case 3 Adhesive 4 Sealing material 5a Input / output lead 5b Input / output lead 6 Sound absorbing material 7 Covering material 8 Covering material 9 Covering material 10 Ultrasonic transmitter / receiver 11 Housing 11a Vibration surface 12 Piezoelectric element 13 Internal space 14 Film 15 Lead 16 Filling

Claims (1)

A piezoelectric element is bonded to the bottom of the bottomed cylindrical case to form a unimorph vibrator, and this is applied to the vibration surface in an ultrasonic transducer that transmits and receives ultrasonic waves on the outer surface of the vibrating body. Among the coatings, at least one layer of a high molecular weight material (silicon, urethane, synthetic rubber, etc.) having a Poisson's ratio of 0.45 to 0.49 and a thickness of 0.1 mm to 1.5 mm is provided. An ultrasonic transducer having a thickness of 1.6 mm or less and constituting a coating that relieves external stress.

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