JP2000152390A - Ultrasonic wave transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce reverberations in a cylindrical case with bottom by sticking a piezoelectric element on the inner bottom face of the cylindrical case and filling the entire internal space of the cylindrical case with a polyurethane foam for absorbing reverberation in the compression state of a specified volume ratio, thereby minimizing the reduction of a reflecting wave receiving level. SOLUTION: A polyurethane foam 11 has a hole through which a lead wire 12a is inserted. A filling material 8 made of an elastic material, such as silicone rubber is injected so as to enclose a space between a board 13 and the cylindrical case 2 with bottom. The board 13 has a hole, through which the lead wire 12a is inserted. One terminal of the read wire 12a is soldered to an electrode face of the piezoelectric element 1. A lead wire 12b takes electrical continuity with the cylindrical case 2 via a conductive adhesive 10. The polyurethane foam 11, whose foaming magnification factor is 25-100, is compressed at the volume ratio of 50-90% and packed in an internal space of the case 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drip-proof ultrasonic transducer for transmitting and receiving an ultrasonic frequency band.

[0002]

2. Description of the Related Art A conventional drip-proof ultrasonic transducer is described below.
A description will be given based on FIG. First, in the figure, reference numeral 1 denotes a piezoelectric element, and the piezoelectric element 1 is bonded to the inside of the bottom surface of the bottomed cylindrical case 2 to constitute a unimorph vibrator. Reference numeral 8 denotes a filler, which is injected so that the space between the substrate 5 with the electrode pattern and the bottomed cylindrical case 2 is sealed. Reference numeral 7 denotes a lead wire. One of the lead wires 7 is soldered to an electrode terminal 6b implanted on the substrate 5 with an electrode pattern, and the other is soldered to the electrode surface of the piezoelectric element 1. Also, the electrode terminal 6a and the electrode pattern 3
Are electrically connected by soldering, and the electrode pattern 3 and the bottomed cylindrical case 2 are bonded to each other via a conductive adhesive 10.

[0003]

In the structure of the conventional drip-proof ultrasonic transducer, when a pulse burst wave as shown in FIG. 3 is applied to the piezoelectric element, the bottom surface of the bottomed cylindrical case vibrates, and At the same time that sound waves are radiated into the air, vibration is also transmitted to the side surface of the bottomed cylindrical case and the lead wire, and a muffled sound remains in the bottomed cylindrical case even after the applied voltage is terminated. As a result, vibration remains inside the bottomed cylindrical case, and the vibration conversely vibrates the piezoelectric element to output an induced voltage. This output voltage becomes a reverberation signal, and there has been a problem that the reception of the reverberation signal becomes impossible during a certain time. FIG. 4 is a diagram showing this reverberation wave, where T1 is the time of the reverberation component. The present invention solves such a problem, and when the piezoelectric element is driven by a pulse burst wave, the reverberation in the bottomed cylindrical case is significantly reduced while minimizing the decrease in the reception level of the reflected wave. It is intended to shorten it.

[0004]

In order to solve the above-mentioned problems, an ultrasonic transducer according to the present invention comprises a unimorph vibrator in which a piezoelectric element is bonded to an inner surface of a bottom of a bottomed cylindrical case. A polyurethane foam having an expansion ratio of 25 to 100 times is sealed in the entire inner space of the bottomed cylindrical case in a compressed state so that the volume ratio becomes 50 to 90%. I do.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG.
FIG. 1 is a schematic structural cross-sectional view of an ultrasonic transducer according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a piezoelectric element, and a piezoelectric element 1 is bonded to an inner surface of the bottom of a bottomed cylindrical case 2 to constitute a unimorph vibrator. Reference numeral 11 denotes a polyurethane foam containing a large amount of an air layer and having a foaming ratio of 25 to 100 times, and is sealed in the entire inner space of the bottomed cylindrical case 2 in a compressed state so that the volume ratio becomes 50 to 90%. . This polyurethane foam 11 has a lead wire 12a
Has a hole for letting through. Reference numeral 8 denotes a filler made of an elastic member such as silicon rubber, which is injected so that the space between the substrate 13 and the bottomed cylindrical case 2 is sealed. Substrate 13
Is provided with a hole for passing the lead wire 12a. One of the lead wires 12 a is soldered to the electrode surface of the piezoelectric element 1. The lead wire 12 b is electrically connected to the bottomed cylindrical case 2 via the conductive adhesive 10. The polyurethane foam 11 having an expansion ratio of 25 to 100 times is sealed in the entire inner space of the bottomed cylindrical case 2 in a state where the polyurethane foam 11 is compressed so that the volume ratio becomes 50 to 90%. While minimizing, the piezoelectric element 1, the bottomed cylindrical case 2, the lead wire 12a, the substrate 13
Reverberation vibration can be efficiently suppressed. At this time,
When the polyurethane foam 11 is compressed and sealed to a state where the volume ratio becomes smaller than 50%, the reflected wave reception level is significantly reduced. Further, if the package is sealed in a compressed state in which the volume ratio exceeds 90%, reverberation vibration cannot be suppressed, and there is a problem in both cases. Similarly, when the expansion ratio of the polyurethane foam is smaller than 25 times or larger than 100 times, the reverberation vibration cannot be suppressed in both cases, and there is a problem. As described above, the polyurethane foam 11 having an expansion ratio of 25 to 100 times is compressed so as to have a volume ratio of 50 to 90%, and is sealed in the entire internal space of the bottomed cylindrical case 2. When the pulse burst wave shown in FIG. 3 is applied to the piezoelectric element 1, the reduction of the reflected wave reception level is minimized,
Reverberation which occurs when the applied voltage ends can be extremely suppressed, and the reverberation time can be significantly reduced as shown in FIG.

[0006]

As described above, according to the present invention, a polyurethane foam having a foaming ratio of 25 to 100 is compressed to a volume ratio of 50 to 90% over the entire inner space of a bottomed cylindrical case. By applying a pulse burst wave to the piezoelectric element, the reverberation time can be significantly reduced while minimizing the decrease in the reflected wave reception level, so that a wide detection area can be maintained. Short distance detection is also possible.

[Brief description of the drawings]

FIG. 1 is a schematic structural sectional view of an ultrasonic transducer according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of an ultrasonic transducer according to a conventional embodiment.

FIG. 3 is a diagram showing a pulse burst wave applied to an ultrasonic transducer.

FIG. 4 is a diagram showing reverberation waves when a pulse burst wave is applied to an ultrasonic transducer according to a conventional embodiment.

FIG. 5 is a diagram showing a reverberation wave when a pulse burst wave is applied to the ultrasonic transducer according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Bottom cylindrical case 3 Electrode pattern 4 Substrate body 5 Substrate with electrode pattern 6a Electrode terminal 6b Electrode terminal 7 Lead wire 8 Filler 9 Solder 10 Conductive adhesive 11 Polyurethane foam 12a Lead wire 12b Lead wire 13 Substrate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsushi Iwasaki, Inventor 372-4, Kunyama, Tottori, Japan Nippon Ceramics Co., Ltd. F-term (reference) 5D019 AA21 BB02 BB13 FF02 GG05

Claims (1)

[Claims] 1. A unimorph vibrator is formed by laminating a piezoelectric element inside a bottom surface of a cylindrical case having a bottom, and an ultrasonic wave transmitting / receiving unit transmits and receives ultrasonic waves on the outer surface of the case of the vibrating body. In the container, a polyurethane foam having a foaming ratio of 25 to 100 times is sealed in the entire inner space of the bottomed cylindrical case in a compressed state so that the volume ratio becomes 50 to 90% for reverberation absorption. Ultrasonic transducer.