JP2002078089A - Ultrasonic wave sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic wave sensor that can stabilize attenuated vibration caused after the end of a drive input signal and makes a reverberation time constant so as to stabilize a distance for detecting an obstacle. SOLUTION: A piezoelectric vibrator is joined with the inside of a bottom face of a cylindrical case with a bottom, an upper face of the piezoelectric vibrator is covered with a foamed elastic body and silicone elastic body is filled in the cylindrical case with bottom including other inner bottom face and side faces in the ultrasonic wave sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic sensor for detecting an obstacle by transmitting and receiving ultrasonic waves.

[0002]

2. Description of the Related Art A sectional view of a conventional drip-proof ultrasonic sensor is shown in FIG. Bottom cylindrical case 7 made of aluminum or the like
The piezoelectric vibrating element 2 is bonded to the inside of the bottom surface of the piezoelectric vibrating element 2 with an adhesive 1. Remove by soldering. The piezoelectric vibrating element 2 and the bottomed cylindrical case 7 are electrically connected, and the piezoelectric vibrating element 2 and the input / output lead 5a and the bottomed cylindrical case 7 and the input / output lead 5b are electrically connected. It is connected to the. A sound absorbing material such as a foamed elastic body 4 is placed on the upper surface of the piezoelectric vibrating element, and a silicon elastic body 6 is filled in the bottomed cylindrical case 7 from above.

[0003]

As shown in FIG. 3, in the conventional drip-proof ultrasonic sensor, the foamed elastic body 4 and the silicon elastic body 6 come into contact with the inner wall of the bottomed cylindrical case 7, and The inner wall of the case 7 has a boundary layer made of a different material. When inputting an electric signal to the ultrasonic sensor and driving it, when a pulse burst signal is input, since the inner wall of the bottomed cylindrical case 7 forms a boundary layer with a different material, the bottomed cylindrical case 7 is integrated. Vibration distortion easily occurs without vibration. As a result, as shown in FIG. 4, attenuation occurs in a distorted state in the reverberation signal after the termination of the electrical input signal. Therefore, in the reverberation after the end of the electrical input signal, the relationship between the time after the end and the reverberation becomes unstable. This means that reverberation becomes unstable due to structural variations of the foamed elastic body 4 and the silicon elastic body 6 filled and inserted into the bottomed cylindrical case 7. This is a problem that, when transmitting and receiving the ultrasonic sensor to detect an obstacle, if the reverberation is unstable, the distance at which the obstacle can be detected is unstable. Further, since the input / output leads 5 taken out from the two locations of the piezoelectric vibrating element 2 and the bottomed cylindrical case 7 are filled with a silicon elastic body and held, the pulling strength is weak and there is a possibility of disconnection. Lack of reliability.

[0004]

Means for Solving the Problems A piezoelectric vibrating element is adhered to the inside of the bottom surface of a bottomed cylindrical case, and the upper surface of the piezoelectric vibrator is covered with a foamed elastic body. Is filled with a silicon elastic body. Furthermore, in the input / output lead which can be taken out from the bottomed cylindrical case, a stopper integrated with the lead wire is provided in the bottomed cylindrical case,
The inside of the bottomed cylindrical case including this stopper is filled with a silicon elastic body.

[0005]

1 and 2 are sectional views illustrating an ultrasonic sensor according to the present invention. As shown in FIG. 1, the piezoelectric vibration element 2 is bonded to the inside of the bottom surface of the bottomed cylindrical case 7 using the adhesive 1. One end 5a of the input / output lead 5 is soldered and removed from the back surface of the piezoelectric vibrating element 2 and a ring is formed in advance so that the silicon elastic body 6 to be filled into the bottomed cylindrical case 7 does not enter this surface. A silicon elastic body 3 is formed around the piezoelectric vibrating element 2, and a foamed elastic body 4 is mounted thereon. The foamed elastic body 4 and the bottomed cylindrical case 7
The inner wall has a gap capable of being filled with the silicon elastic body 6. The other end 5b of the input / output lead 5 is soldered out of the case 7 and taken out. The interior of the bottomed cylindrical case 7 thus formed, including the input / output lead wires 5, is filled with the silicon elastic body 6. Further, in order to increase the tensile strength of the input / output lead 5, as shown in FIG.
Is filled, and the silicon elastic body 6 is filled. The lead stopper 8 is set so as not to touch the inner wall of the bottomed cylindrical case 7 and the foamed elastic body 4. The lead stopper was disk-shaped. The shape of the lead stopper 7 may be any shape such as a disk shape, a square plate shape, a spherical shape, or a polyhedron, as long as it is filled with the silicon elastic body 6 and becomes a load.

[0006]

As shown in FIG. 5, the reverberation after the end of the drive input signal becomes an integrated vibration by filling the inside of the case with the silicon elastic body, and the vibration is attenuated. Accordingly, the damped vibration is stabilized and the reverberation time is fixed, so that the distance for detecting an obstacle is stabilized.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of an ultrasonic sensor according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional ultrasonic sensor.

FIG. 4 shows the reverberation of a conventional ultrasonic sensor.

FIG. 5 shows the reverberation of the ultrasonic sensor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Adhesive 2 Piezoelectric vibration element 3 Ring-shaped silicon elastic body 4 Foam elastic body 5 Input / output lead 6 Silicon elastic body 7 Bottom cylindrical case 8 Lead stopper

Claims (2)

[Claims] 1. An ultrasonic sensor in which a piezoelectric vibrating element inside a bottom surface of a bottomed cylindrical case is adhered, wherein an upper surface of the piezoelectric vibrating element is covered with a foamed elastic body, and an inner bottom surface of another bottomed cylindrical case. An ultrasonic sensor characterized by filling the inside of a bottomed cylindrical case including a side surface with a silicon elastic body. 2. An input / output lead wire taken out of a case, a lead stopper integrated with the lead wire is provided in the bottomed cylindrical case, and the inside of the bottomed cylindrical case including the stopper is formed of a silicon elastic body. The ultrasonic sensor according to claim 1, wherein the ultrasonic sensor is filled with: