JPH03270399A - Drip-proof ultrasonic microphone - Google Patents

Abstract

PURPOSE:To improve short distance detecting performance by giving an oscillation suppressing function to a resonator, decreasing reverberation due to the oscillation of the resonator and improving the detecting sensitivity of a wave receiving signal. CONSTITUTION:A resonator 2 comprises of a resonance ring 21 and an oscillation damping member 22. The oscillation damping member 22 is formed in an O ring shape with a material lower in natural frequency than that of the resonance ring 21, for example, rubber or the like and fitted into a recessed groove 21a. The oscillation energy of the resonator 2 due to the oscillation of an oscillator 1 at the time of transmitting wave is thermally consumed by the resistance for suppressing the oscillation of the oscillation damping member 22 to thereby prevent excitation. The reverberation due to the oscillation of the resonator 2 is damped by the time of wave receiving, so that a wave receiving signal is easily detected. Thus, a short distance detecting performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drip-proof ultrasonic microphone that is integrated in transmitting and receiving waves.

[Conventional technology]

A conventional drip-proof ultrasonic microphone is an integrated wave transmitting/receiving type that is driven by inputting a tone burst wave at a constant or arbitrary period to a piezoelectric element.As shown in Fig. 5, a vibrating body 1 ．． Resonator 2. The main component is a base 3° and a vibration isolator 4 (for example, see Japanese Utility Model Application Publication No. 59-154985).

The vibrating body 1 is formed by fixing a piezoelectric element 12 to the bottom inner surface of a bottomed cylindrical vibrating case 11. The vibration case 11 is made of aluminum and serves as one conductor when the piezoelectric element 12 is polarized. The piezoelectric element 12 is made of PZT-based piezoelectric ceramic and is formed into a disk shape, has electrodes on both sides, is bonded to the vibration case with a conductive adhesive on the negative side, and is connected to a lead wire on the other side.

The resonator 2 is made of a metal material, has a ring shape with a predetermined axial length, and is fixed near the axial center of the vibration case 11 .

The base 3 has + and - ends 73132 that are electrically connected to the electrodes of the vibration case 11 and the piezo element 12 via lead wires 7, and the opening 11a of the vibration case 11. They are engaged through the body 4 and fixed with the filler 5.

Vibration isolator 4; is located between the resonator 2 and the base 3, is fitted to the inner periphery of the vibration case 11, engages and holds the base 3, and is attached to the base 3.
This prevents vibrations from being transmitted to the

This device is used to receive the sound waves reflected by the object to be detected at a timing when the reverberation of the vibrating body 1 becomes low after the waves are transmitted.

[Problems to be Solved by the Invention] When the drip-proof ultrasonic microphone described above 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 arise.

In this case, the distance between the car and the obstacle is short, so G
A sound wave reflected by an obstacle is received at a timing when the reverberation of the vibrating body 1 is high. As a result, the SN ratio becomes small and the detection accuracy becomes poor. Moreover, since the resonator 2 and the vibration case 11 are fixed to the rigid body 6, the resonator 2 itself is excited, resulting in a long reverberation time. Therefore, there is a problem that short-range detection performance cannot be improved.

The present invention was made in view of the above circumstances, and its object is to provide a drip-proof ultrasonic microphone in which the reverberation time of the vibrating body is shortened.

[Means to solve the problem]

In order to achieve the above-mentioned object, the drip-proof ultrasonic microphone according to claim (1) has a piezoelectric element fixed to the bottom inner surface of a bottomed cylindrical vibration case. A resonator fixed to the middle of the case, a base fixed to the opening of the vibration case and having + and - terminals, and a shield fitted to the inner circumference of the vibration case and sandwiched between the resonator and the base. A drip-proof ultrasonic microphone comprising a vibrator, the resonator having a vibration suppressing function.

In the drip-proof ultrasonic microphone according to claim (2), the resonator has a structure in which a damper is attached to the resonator.

In the drip-proof ultrasonic microphone 1 cophone according to claim (3), the resonator has a structure in which the resonator maintains a predetermined external dimension that is fixed to the vibration case and is provided with a recess or the like. .

[Effect]

The drip-proof ultrasonic microphone according to claim (1) prevents excitation by consuming the vibration energy of the resonator due to the vibration of the vibrator during wave transmission through a resistance of the vibration suppressing function of the resonator;
The reverberation caused by the vibration of the resonator is attenuated by the time of wave reception, making it easier to detect the received signal.

In the drip-proof ultrasonic microphone according to claim (2), various reverberation attenuation levels can be selected depending on the mass of the damper, the mounting position, and the mounting method, so as to correspond to the required level of design. I'm making it easy.

The drip-proof ultrasonic microphone according to claim (3) makes it possible to select various reverberation attenuation levels depending on the amount and position of the leak without increasing the number of parts, thereby meeting the required level of design. I'm making it easy.

[Example] Hereinafter, a first example of the present invention will be described based on FIG. 1.

The main part of the drip-proof ultrasonic microphone of the present invention is the resonator 2.
It is in. Since the members other than this essential part are the same as those of the conventional example described above, substantially the same members are given the same reference numerals and detailed explanations will be omitted.

The resonator 2 includes a resonant ring 21 and a damper 22.

The resonance ring 21 has an outer circumference fixed to the vibration case by press fitting or adhesive, and has a groove 21a on the inner circumference. In addition,
The groove 21a may be formed on the outer periphery or on the end surface G.

The damper 22 is made of a material having an extremely lower natural frequency than the resonance ring 21, such as rubber, and is formed into an O-ring shape, and is fitted into the groove 21a. Note that the damping body 22 may be formed by outsert molding.

In this structure, the vibration energy of the resonator 2 caused by the vibration of the vibrator 1 during wave transmission is consumed as heat by the vibration suppressing resistance of the vibration suppressor 22, thereby preventing excitation.

Next, a second embodiment of the present invention will be explained based on FIG. 2 in the same manner as the first embodiment.

The main part of this is in the damper 22 of the resonator 2.

The damper 22 is fixed to the inner peripheral surface of the resonance ring 21 by press fitting or adhesive. Note that it may also be fixed to the end face of the resonance ring 21.

Next, a third embodiment of the present invention will be described based on FIG. 3 in the same manner as the first embodiment.

The main part of this is the resonant ring 21 of the resonator 2.

The resonance ring 21 is formed by laminating a plurality of ring materials 23 and a damping material 24 between them in the axial direction.

Note that lamination molding may be performed in the radial direction.

Next, a fourth embodiment of the present invention will be described based on FIG. 4 in the same manner as the first embodiment.

The main part of this is the resonant ring 21 of the resonator 2.

The resonant ring 21 has a groove 21a on its inner peripheral surface.

Note that the groove 21a may be provided on the outer periphery or end face. Alternatively, the groove 21a may be formed hollow by providing a ring material 23.

This device absorbs the vibration energy of the resonator 2 caused by the vibration of the vibrator 1 during wave transmission by using the vibration suppression resistance of the resonator 2.
It consumes heat and prevents excitation.

〔Effect of the invention〕

Since the drip-proof ultrasonic microphone of the present invention shortens the reverberation time due to the vibration of the resonator and increases the detection sensitivity of the received signal, it is possible to improve short-range detection performance.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the invention, FIG. 2 is a sectional view showing a second embodiment of the invention, and FIG. 3 is a sectional view showing a third embodiment of the invention. (a) is a sectional view, (b) is a sectional view of a modified example thereof, and FIG. 4 shows a fourth embodiment of the present invention, (a) is a sectional view, and (b) is a sectional view thereof. A sectional view of a modified example; FIG. 5 is a sectional view of a conventional example.・Vibration body, resonator, base, vibration isolator. Figure 1

Claims (3)

[Claims] (1) A vibrator consisting of a piezoelectric element fixed to the bottom inner surface of a cylindrical vibration case with a bottom, a resonator fixed to the middle of the vibration case, and + and - terminals fixed to the opening of the vibration case. A drip-proof ultrasonic microphone comprising a base having a vibration damper, and a vibration isolator fitted to the inner periphery of a vibration case and sandwiched between the resonator and the base, wherein the resonator is provided with a vibration suppression function. A drip-proof ultrasonic microphone characterized by: (2) The drip-proof ultrasonic microphone according to claim (1), characterized in that a vibration damper is attached to the resonator. (3) The drip-proof ultrasonic microphone according to claim (1), wherein the resonator is provided with a recess or the like while maintaining a predetermined external dimension that is fixed to the vibration case.