Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Housed microphone
Reexamination Certificate
1998-05-27
2001-10-23
Le, Huyen (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Housed microphone
C381S361000, C381S368000, C439S086000
Reexamination Certificate
active
06307946
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a miniature microphone component that is optimized for insertion into the main body of a small-size communication device such as a mobile phone or a mobile radio.
BACKGROUND OF THE INVENTION
At present, the development of ever smaller and lighter small-size portable communication devices is well-stablished, and thus microphone elements to be used as components of such communication devices are also becoming smaller. For the installation of a miniature microphone in such a communication device, a thin lead wire is soldered to connect the terminals of the miniature-microphone-side to the terminals on a circuit board in the main body of the small-size communication device, and then the miniature microphone is covered with a rubber casting as a waterproof seal and inserted into the small-size communication device.
However, the process of attaching the miniature microphone by soldering with a thin lead wire leads to problems in that the product quality is not steady, because this process involves a delicate soldering job that has to be performed by hand and hardly can be automatized, and the installation space cannot be made narrower, since the lead wire has to be connected.
In order to overcome these problems of the prior art, it is a purpose of the present invention to provide a miniature microphone component with a rubber connector with anisotropic conductivity for an installation method wherein the soldering job is eliminated, thus facilitating the assembly, and the installation space can be made very small.
SUMMARY OF THE INVENTION
The miniature microphone component using a rubber connector with anisotropic conductivity according to the present invention, comprises a miniature microphone having a terminal area; a rubber casting for protection against vibration covering the circumference of the miniature microphone; and a rubber connector with anisotropic conductivity (called a “zebra-type rubber connector with anisotropic conductivity” in the following) comprising electrically conductive layers and electrically isolating layers, which is clamped and retained to have areal contact with the terminal area of the miniature microphone. The miniature microphone, the rubber casting for protection against vibration covering the miniature microphone and the conductive rubber connector with anisotropic conductivity are integrated into one component. According to this structure, the miniature microphone component of the present invention can be installed simply by pressing it against a terminal portion on a circuit board, and the steps of soldering and wiring a lead wire can be omitted. Furthermore, the installation space can be minimized.
It is preferable that the rubber connector with anisotropic conductivity is shaped so that none of its electrically conductive layers has contact with more than one terminal of the miniature microphone at a time. When an electrically conductive layer has contact with two or more terminals at the same time, it causes a short between those terminals, so that the miniature microphone cannot function correctly.
It is preferable that the rubber casting for protection against vibration is made of silicone rubber, because silicone rubber has high weather resistance and provides an excellent protection against vibration.
Possible materials to be used for the rubber members of the rubber connector with anisotropic conductivity include polybutadiene, natural rubber, polyisoprene, styrene-butadiene copolymer rubber (SBR), butadiene-acrylonitrile copolymer rubber (NBR), ethylene-propylene nonconjugated diene copolymer (EPDM), ethylene-propylene copolymer (EPM), polyurethane-polyester-based rubber, chloroprene rubber, epichlorohydrin rubber and silicone rubber. However, considering its electrical properties and weather resistance, silicone rubber is the most preferable.
It is preferable that the electrically conductive layers of the rubber connector with anisotropic conductivity comprise, per 100 weight parts of rubber component, 1-400 weight parts, more preferably 100-300 weight parts, of at least one electrically conductive powder selected from the group consisting of platinum, gold, silver, nickel, cobalt, copper, tin, aluminum and palladium metal powder; an alloy powder containing solder; a conductive powder of organic polymer powder that has been coated with a metal; and a conductive powder of inorganic powder that has been coated with a metal.
It is also preferable that the electrically conductive layers of the rubber connector with anisotropic conductivity comprise 10-150 weight parts carbon powder, more preferably 40-100 weight parts, per 100 weight parts rubber component. Good conductivity is not attained, when the added amount of electrically conductive powder or carbon powder is below these ranges. When the added amount of electrically conductive powder or carbon powder is above these ranges, the conductivity hardly increases, and the formability and the compression resilience of the rubber connector are inhibited.
It is preferable that the zebra-type rubber connector with anisotropic conductivity is elastically compressible and can be installed by area-contacting it with a terminal portion on a circuit board. When the rubber connector is elastically compressible, it can elastically deform in an appropriate manner to be compressed between a terminal of the miniature microphone and a terminal of the circuit board when the miniature microphone component is built into a small-size communication device. Thus, the rubber connector can establish secure areal contact between the two terminal areas. As a result, this increases the reliability of the electric connection. Furthermore, the miniature microphone is retained elastically against vibration by the rubber connector and the rubber casting, and its vibration resistance is increased.
It is preferable that the rubber members have a compression resilience of 30-80 measured with Method A in JIS K6301. If the compression resilience is below this range, the elastic deformation of the rubber connector becomes large, and the conductivity becomes pressure sensitive, so that the electric contact resistance to the terminals of the circuit board becomes unstable. If the compression resilience is above this range, the elastic deformation of the rubber connector becomes small, so that the reliability of the electric contact with the terminals of the circuit board decreases. Method A in JIS K6301 for measurement of the compression resilience is performed as follows: A sample piece of the size specified in JIS K6301 is prepared from the material to be tested. An A-type spring-based hardness meter according to JIS K6301 is used as the measuring instrument. Method A in JIS K6301 is in conformity with Type A in ASTM D2240.
The miniature microphone component according to the present invention can be used in various applications, but it is preferable that it is built into a small-size portable communication device such as a mobile phone. The miniature microphone component according to the present invention can be assembled without soldering a lead wire to it, so that the installation space can be minimized. The reliability of the electrical connection and the vibration resistance can be increased simultaneously, because the miniature microphone is clamped in and retained by the rubber connector and the rubber casting against vibration. This can add to the product value of small-size portable communication devices, for which an increase of miniaturization and reliability is especially desirable.
In a miniature microphone component using the above zebra-type rubber connector with anisotropic conductivity, a highly reliable electrical contact can be established just by slightly compressing the zebra-type rubber connector with anisotropic conductivity between the terminal area of the miniature microphone and the terminal area on the circuit board inside the small-size communication device. Moreover, the zebra-type rubber connector with anisotropic conductivity is conductive o
Fujimoto Mitsuhiro
Okayasu Takako
Fuji Polymer Industries Co., Ltd.
Le Huyen
Merchant & Gould P.C.
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