Waterproof type microphone

Details Waterproof type microphone Waterproof type microphone

1999-08-27

2001-02-13

Le, Huyen (Department: 2743)

Electrical audio signal processing systems and devices

Electro-acoustic audio transducer

Housed microphone

C381S355000, C381S367000, C128S201190

Reexamination Certificate

active

06188773

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a waterproof type microphone, and more specifically, to a waterproof type microphone which enables equivalent pressures between the interior of an unit accommodating chamber and the outside of a casing without impairment of the waterproof function.
BACKGROUND OF THE INVENTION
A headset type microphone is worn on the head of a user for a long period of time. For the reason, the headset microphone is different from a hand-held type microphone that it is often suffered from liquid such as sweat and spittle of the user. In addition, the headset microphone is often submerged in water of for example, swimming pool by sports instructors. As a result, such the liquid sometimes adversely affects the headset microphone.
Besides the headset microphone, for example, “Karaoke” (or orchestra) microphone is used in entertainment facilities where beverages such as beer and juice are served. For the reason, such the microphone is suffered from the beverage dashed thereon, and erroneous dropping thereof into the beverage.
Accordingly, as shown in
FIG. 5
, in a conventional accommodation of a mike unit
2
into an unit accommodating chamber
1
a
of a mike casing
1
, a sound receiving opening portion
1
b
of the mike casing
1
is covered with a waterproof membrane
3
, and an O-ring
5
a
is interposed between a support arm
4
of a headset and the mike casing
1
so that the unit accommodating chamber
1
a
is kept airtightly.
In this instance, the waterproof membrane
3
comprises a thinner plastic film made of materials such as polyethylene, and polyethylene terephtalate, which does not seriously affect vibration energy of sound wave passing therethrough so that excellent sensitivity, frequency characteristic and directivity are produced.
Furthermore, to provide an excellent acoustic characteristics, the waterproof membrane
3
is put on a support ring
3
a
in such a way not to be pulled by large tension applied thereto, and covers over a sound receiving opening portion
1
b
through the support ring
5
a
. In addition, an O-ring
5
b
is also provided between the support ring
3
a
and the mike casing
1
.
However, the waterproof membrane
3
and the O-rings
5
a
,
5
b
seal the interior of the unit accommodating chamber
1
a
almost completely. So, the waterproof membrane
3
undergoes pressure differential between the interior of the unit accommodating chamber and the outside of the mike casing due to the changes in external atmospheric pressure and internal temperature and the like. consequently, the waterproof membrane
3
has a resonant point under tension. Theerefore, the acoustic characteristics become lessened. The possibility arises that the waterproof membrane
3
will be broken.
To prevent this, the internal volume of the unit accommodating chamber is increased. When the sound receiving portion cannot be formed in larger size, a bypass passage then brings the sound receiving portion into communication with a large volume portion which is separately formed within the mike casing, as proposed, for example, in Japanese Utility Model Publication No. 7-28793 Publication.
However, any of objectives of methods mentioned above is to maintain airtightness of the interior of the unit accommodating chamber. Therefore, basically, the problem of the pressure differential between the interior of the unit accommodating chamber and the outside of the mike casing is not solved. In order to solve the problem, it is contemplated to provide permeability for the waterproof membrane itself. However, an acoustically desirable material is even yet not found such the waterproof membrane.
Such the problem will be accomplished by the present invention. Accordingly, an object of the invention is to provide a waterproof type microphone which equalizes the pressures between the interior of an unit receiving chamber and the outside of a mike casing without degradation of the waterproof performance and acoustic characteristics.
SUMMARY OF THE INVENTION
For the achievement of the object described above, the present invention provides a waterproof type microphone including a mike casing disposed in an unit accommodating chamber having a sound receiving opening; the unit accommodating chamber having a mike unit accommodated therein, and a membrane mounted on said sound receiving opening, wherein said mike casing has a venting hole which brings said unit accommodating chamber into communication with the outside of the mike casing, and a water non-permeability membrane mounted on the venting hole thereof.
According to the above-mentioned arrangement, since the interior of the mike casing is connected with the outside thereof through the venting hole, no pressure differential between inside and outside occurs. Therefore, the waterproof membrane is not pulled by high tension to excess. Further, since the venting hole has a water non-permeability venting membrane mounted thereon, the mike casing is not susceptible to the entry of liquids from the outside thereof.
In the present invention, a support ring for supporting said waterproof membrane has an internal peripheral edge formed on the side of a waterproof membrane supporting face, and preferably the internal peripheral edge has a protective surface with a predetermined inclined angle or a predetermined curvature. Thereby, the waterproof membrane will be avoided from breakage thereof.
Furthermore, preferably, the waterproof membrane is supported on the support ring by an adhesive material which exhibits viscosity (elasticity) even after setting. Thereby, even though the waterproof membrane is pulled out by tension, the adhesive material with the viscosity will damp the tension.
The present invention also includes a waterproof membrane having a resonance preventing portion which is formed by fine rugged notches thereon.


REFERENCES:
patent: 6018585 (2000-01-01), Akino et al.
patent: 2064265 (1981-06-01), None

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