JPH04220900A - Drip-proof type ultrasonic microphone - Google Patents

Abstract

PURPOSE:To eliminate undesired vibration and to reduce reverberation time by providing a vibration proof part made of a vibration proof rubber to an inner face of a vibration case having a piezoelectric element. CONSTITUTION:The drip-proof type ultrasonic microphone has a vibrator 1 and a vibration proof rubber 2. The vibrator 1 is formed cylindrical with a bottom and a piezoelectric element 7 is fixed to the bottom face 3 of a vibration case 6 having a conical slope 5 between the bottom part 3 and a cylinder 4. The vibration rubber 2 is fitted to the slope 5 and forms the vibration part 10 abutting on an opening end 9 of the cylinder 4. Through the configuration above, the vibration energy of the slope 5 due to the vibration of the vibration case 6 is absorbed by the vibration proof rubber 2, then the reverberation time is reduced.

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 microphone of integrated transmitting and receiving type.

0002

2. Description of the Related Art A conventional example is shown in FIG. That is, this drip-proof ultrasonic microphone is an integrated wave transmitting/receiving type that is driven by inputting a tone burst wave to a piezoelectric element at a constant or arbitrary period, and has a cylindrical shape with a bottom. A piezoelectric element 54 is fixed to the bottom part 50 of a vibration case 53 having a conical inclined part 52 between the cylindrical part 51 and the cylindrical part 51, and a vibration isolating rubber 55 is fitted to the inclined part 52. The vibration case 53 is made of aluminum and serves as one conductor when the piezoelectric element 54 is driven. The piezoelectric element 54 is made of PZT-based piezoelectric ceramic and is formed into a disk shape, and has electrodes on both sides, one side of which is bonded to the bottom part 50 with a conductive adhesive, and the other side is connected to the lead wire 56. . The vibration-proof rubber 55 is the vibration case 53
The vibration of the inclined portion 52 is suppressed. A shield wire 57 is fitted into a slit 58 provided in the center of the vibration isolating rubber 55 and connected to the vibration case 53 via lead wires 56 and 59.
and are connected to the electrodes of the piezoelectric element 54. After the shield wire 57 is fitted, the opening of the vibration case 53 is sealed with the sealant 6.
It is fixed and sealed by 0.

0003

[Problems to be Solved by the Invention] When a drip-proof ultrasonic microphone is installed in a corner of a car and used to detect the distance between the car and an obstacle from the driver's seat, the following problems occur. . In other words, the distance between the vehicle and the obstacle is short, and the vibration case 53 receives the sound waves reflected by the obstacle at a timing when the reverberation is high, so that the reverberation time T2 with respect to the wave transmission time T1 becomes shorter as shown in Fig. 11. becomes longer, so S
The N ratio becomes small and the detection accuracy becomes poor.

In order to shorten this reverberation time, in the conventional example, the cylindrical portion 51 of the vibration case 53 is made thinner to reduce the mass of the vibration case 53, and a vibration isolating rubber 53 for damping is provided on the inclined portion 52. The reverberation time T2 was intended to be reduced by suppressing the vibration of the inclined portion 52 through contact. However, as shown in FIG. 12, unnecessary vibrations caused by the cylindrical portion 51 occur during the time T3, resulting in a disordered reverberation waveform, resulting in a drawback that a stable reverberation waveform cannot be obtained.

On the other hand, the cylindrical portion 51 of the vibration case 53
When damping is performed, the nodes of vibration of the vibration case 53 change, resulting in a significant reduction in the resonant frequency. Further, if the cylindrical portion 51 is completely removed, it becomes difficult to hold the microphone itself. Therefore, an object of the present invention is to provide a drip-proof ultrasonic microphone that can eliminate unnecessary vibrations and shorten reverberation time.

[0006]

[Means for Solving the Problems] A drip-proof ultrasonic microphone according to claim 1, in which a vibration-proof rubber is fitted to the inclined part of the vibration case, makes contact with the open end of the cylindrical part of the vibration case. The present invention is characterized in that a vibration isolating portion is formed on the vibration isolating rubber. According to a second aspect of the present invention, in the drip-proof ultrasonic microphone according to the first aspect, the vibration isolating portion is in contact with an end surface of the open end portion of the cylindrical portion.

The drip-proof ultrasonic microphone according to claim 3 comprises:
In the first aspect of the present invention, the open end of the cylindrical portion is curled inward, and the curled end surface is brought into surface contact with the vibration isolating portion. A fourth aspect of the drip-proof ultrasonic microphone according to the first aspect is characterized in that the open end of the cylindrical portion is curled inward, and the vibration isolating portion is composed of a plurality of pieces that make point contact with the curled end surface. be.

[0008]

[Function] According to the drip-proof ultrasonic microphone of claim 1, the vibration energy of the inclined part due to the vibration of the vibration case during wave transmission is absorbed by the vibration isolating rubber, so the reverberation time can be shortened, and the cylindrical part The vibration energy is thermally consumed by the vibration isolator that contacts the open end of the cylindrical portion and prevents excitation, so unnecessary vibrations are suppressed. As a result, the detection sensitivity of the received signal increases and short-range detection performance can be improved.

According to the drip-proof ultrasonic microphone of claim 2, since the vibration isolating portion is in contact with the end surface of the open end of the cylindrical portion, the same effect as that of claim 1 can be obtained. be. According to the drip-proof ultrasonic microphone of claim 3,
In the first aspect, the open end of the cylindrical portion is curled inward, and the curled end surface is in surface contact with the vibration isolating portion, so that the same effect as in the first aspect is obtained.

According to the drip-proof ultrasonic microphone according to claim 4, in claim 1, the open end of the cylindrical portion is curled inward, and the vibration isolating portion includes a plurality of pieces in point contact with the curled end surface. Therefore, it has the same effect as claim 1.

[0011]

[Embodiment] The first embodiment of this invention is shown in FIGS. 1 and 2.
This will be explained using figures. That is, this drip-proof ultrasonic microphone has a vibrating body 1 and a vibration-proof rubber 2. Vibrating body 1
A piezoelectric element 7 is attached to the bottom part 3 of a vibration case 6 which has a bottomed cylindrical shape and has a conical inclined part 5 between the bottom part 3 and the cylindrical part 4.
becomes stuck. The vibration case 6 is made of aluminum and serves as one conductor when the piezoelectric element 7 is driven, and the cylindrical portion 4 is formed thin to reduce weight. The piezoelectric element 7 is made of PZT-based piezoelectric ceramic and is formed into a disk shape, and has electrodes on both sides. One side is bonded to the bottom part 3 with a conductive adhesive, and the other side is connected to the lead wire 8 via the bonding part 20. is connected to.

The vibration isolating rubber 2 forms a vibration isolating portion 10 that fits into the inclined portion 5 and abuts against the open end 9 of the cylindrical portion 4. The vibration isolating rubber 2 is made of a material such as rubber, which has an extremely low natural frequency compared to the vibration case 6, and has a structure that fits tightly inside the vibration case 6, and is opposed to the bottom surface 3 of the vibration case 6. A recess 11 is formed at a position where the piezoelectric element 7 can be accommodated without contacting the bottom surface 3, and
The diameter of the outer peripheral surface 12 is made small so as not to contact the inner peripheral surface of the cylindrical part 4, and only the vibration isolating part 10 is formed into a brim shape.
0 is in close contact with the inner circumferential surface of the open end 9. Further, a protrusion 16 for forming a slit 14 into which the shield wire 13 is fitted is formed at the center of the vibration isolating rubber 2, and an insertion hole 15 for guiding the lead wires 8, 22 is formed. 1
A sealant 7 seals and fixes the opening side of the vibration case 6 after the shield wire 13 is fitted. 21 is a joint portion of the lead wire 2.

According to this embodiment, the vibration energy of the inclined part due to the vibration of the vibration case 6 during wave transmission is absorbed by the vibration isolating rubber 2, so that the reverberation time can be shortened, and the vibration energy of the cylinder part 4 is absorbed by the vibration isolator 2. Vibration isolating part 10 that abuts opening end 9 of part 4
As shown in FIG. 2, it can be seen that unnecessary vibration (T3) is suppressed compared to FIG. 12 because heat is consumed and excitation is prevented. T1 is the transmission time, and T2 is the reverberation time. Therefore, it can be seen that the detection sensitivity of the received signal increases and the short-range detection performance can be improved.

A second embodiment of the invention is shown in FIG. That is, in this drip-proof ultrasonic microphone, in the first embodiment, the vibration isolating part 10 is brought into contact with the end surface of the open end 9 of the cylindrical part 4 of the vibration case 6, so that the cylindrical part 4 It is possible to damp only the end face. Others are 1st
This embodiment has the same structure as the embodiment described above, and has the same effects.

A third embodiment of the invention is shown in FIGS. 4 to 6. That is, in this drip-proof ultrasonic microphone, in the first embodiment, the open end 9 of the cylindrical portion 4 is curled inward, and the curled end surface is brought into surface contact with the vibration isolating portion 10. In this case, a protrusion 19 having a donut shape with a semicircular cross section and a partial notch 19a is formed on the rear surface of the vibration isolating rubber 2 opposite to the insertion side into the vibration case 6, and the vibration isolating part 10 is attached to the tip of the protrusion 19 as a cylindrical part. It is formed into a cylindrical shape concentric with 4. Further, the outer circumferential surface 12 is formed by the outer circumferential surface of the vibration isolating portion 10 and the surface of the protrusion 19. As a result, the open end 9 of the cylindrical portion 4 is damped all around, and the open end 9 is also damped by the sealant 17.
Can be sealed by The rest has the same structure as the first embodiment, and has the same effects.

A fourth embodiment of the present invention is shown in FIG. 9 without FIG. That is, in the first embodiment, this drip-proof ultrasonic microphone has an opening end 9 of the cylindrical portion 4 that is curled inward, and a vibration isolator 10 that is made up of a plurality of pieces that make point contact with the curled end surface. It is. In this case, a donut-shaped protrusion 19 with a semicircular cross section is formed concentrically with the cylindrical part 4 on the rear surface of the anti-vibration rubber 2 opposite to the insertion side into the vibration case 6, and the anti-vibration part 10 is attached to the tip of the protrusion 19 around the circumference. The outer circumferential surface 12 is formed by the outer circumferential surface of the protruding rims 19. 19
b is a notch for accommodating the joint portion 21. According to this embodiment, the open end 9 of the cylindrical portion 4 can be damped all around, and the open end 9 can also be sealed with the sealant 17. The rest of the structure is the same as that of the first embodiment, and there are similar effects.

[0017]

Effects of the Invention The drip-proof ultrasonic microphone according to claim 1 has a vibration-proof rubber fitted to the inclined part of the vibration case having a piezoelectric element, and a vibration-proof part that comes into contact with the open end of the cylindrical part of the vibration case. Because it is made of anti-vibration rubber, it is possible to eliminate unnecessary vibrations and shorten the reverberation time, which has the effect of increasing the detection sensitivity of the received signal and improving short-range detection performance. .

The drip-proof ultrasonic microphone of claim 2 comprises:
In the first aspect, since the vibration isolating portion is in contact with the end surface of the open end of the cylindrical portion, the same effect as in the first aspect can be obtained. The drip-proof ultrasonic microphone according to claim 3 is characterized in that, in claim 1, the open end of the cylindrical portion is curled inward, and the curled end surface is in surface contact with the vibration isolating portion.
has the same effect.

The drip-proof ultrasonic microphone according to claim 4 includes:
In the first aspect, the opening end of the cylindrical portion is curled inward, and the vibration isolating portion is composed of a plurality of pieces that make point contact with the curled end surface, so that the same effect as in the first aspect can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a first embodiment of the invention.

FIG. 2 is a diagram of the reverberation waveform.

FIG. 3 is a sectional view of a second embodiment.

FIG. 4 is a sectional view of a third embodiment.

FIG. 5 is a plan view of the anti-vibration rubber.

FIG. 6 is a sectional view thereof.

FIG. 7 is a sectional view of the fourth embodiment.

FIG. 8 is a plan view of the anti-vibration rubber.

FIG. 9 is a sectional view thereof.

FIG. 10 is a sectional view of a conventional example.

FIG. 11 is a reverberation waveform diagram of a general drip-proof ultrasonic microphone.

FIG. 12 is a reverberation waveform diagram of the conventional example.

[Explanation of symbols]

2 Anti-vibration rubber 3 Bottom part 4 Cylinder part 5 Slope part 6 Vibration case 7 Piezoelectric element 9 Open end 10 Vibration isolation part

Claims (4)

[Claims] Claim 1: A piezoelectric element is fixed to the bottom of a vibration case that is cylindrical with a bottom and has a conical slope between the bottom and the cylinder, and a vibration isolating rubber is fitted to the slope. What is claimed is: 1. A drip-proof ultrasonic microphone, characterized in that a vibration-proofing portion that abuts the open end of the cylindrical portion is formed in the vibration-proofing rubber. 2. The drip-proof ultrasonic microphone according to claim 1, wherein the vibration isolating portion abuts an end surface of the open end of the cylindrical portion. 3. The drip-proof ultrasonic microphone according to claim 1, wherein the open end of the cylindrical portion is curled inward, and the curled end surface is in surface contact with the vibration isolating portion. 4. The drip-proof ultrasonic microphone according to claim 1, wherein the open end of the cylindrical portion is curled inward, and the vibration isolating portion comprises a plurality of pieces that make point contact with the curled end surface.