JPH0245919Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial fields of application The invention can be applied to various types of watches, cameras, microwave ovens, and portable devices, for example. video. tape. Regarding acoustic transducers used for sound reporting in recorders, pocket bells, etc., when leading the power supply lead wire of the acoustic converter built into the case to the outside of the case, silicone rubber resin is applied to the lead wire lead-out part. By filling the lead wire, the external force applied to the lead wire is absorbed and alleviated by the silicone rubber resin, making it possible to prevent lead wire breakage accidents.

Prior Art Although piezoelectric type acoustic transducers are known as this type of acoustic transducer, recently, electromagnetic type acoustic transducers that have a resonance point in a low frequency region of around 2 _KHz have been attracting attention.
This electromagnetic acoustic transducer excites a diaphragm through magnetic interaction between a direct current magnetic field and an alternating current magnetic field to obtain vibrating sound.

FIG. 2 is a front cross-sectional view of a conventional example of an electromagnetic acoustic transducer, in which the coil 2 is directly wound around the iron core 3 that is integrally installed approximately at the center of the yoke 4, and the yoke 4 is A cylindrical permanent magnet 5 such as a ferrite magnet or a plastic molded magnet is arranged near the outer periphery of the upper surface so as to surround the electromagnet consisting of the coil 2 and iron core 3. By mounting the diaphragm 6, an acoustic transducer is constructed, and this acoustic transducer is inserted into the bottom of the cylindrical case 1 made of a non-magnetic metal material or synthetic resin at the yoke 4 by press-fitting, etc. It has a structure in which it is inserted by means.

In the acoustic transducer described above, when the coil 2 is driven by applying an AC voltage of an appropriate frequency, the magnetic interaction between the electromagnet and the permanent magnet 5 made up of the coil 2 and the iron core 3 causes an air gap G to the iron core 3. The diaphragm 6, which is opposed to each other via the diaphragm 6, is excited and generates vibration sound.

By the way, when coil 2 is wound around a coil bobbin,
When adopting a structure in which this coil bobbin is inserted into the iron core 3, it is often possible to adopt a structure in which lead terminals are implanted in the coil bobbin or circuit board, and the coil terminals are connected to this, and the coil terminal processing is required. It's easy. On the other hand, in the case of a structure in which the coil 2 is directly wound around the iron core 3, there is a strong demand for miniaturization, and the yoke 4 constituting the bottom plate of the case 1 is provided with holes or notches, etc., without using lead terminals. Opening 4
1 and through this opening 41, the coil 2
It is common to lead out the coil terminals 21 and 22 to the outside of the case 1 and use them as power supply lead wires. In this case, in order to specify the acoustic characteristics, it is necessary to close the opening 41. Conventionally, the opening 41 has been filled with epoxy resin 7 as a closing means.

Problems to be Solved by the Invention However, after the epoxy resin 7 is cured, it becomes extremely hard and loses its elasticity. Therefore, when a thermal shock is applied or the ambient temperature changes cyclically and the epoxy resin 7 thermally expands and contracts, tensile and compressive forces are applied to the lead wires 21 and 22, causing the lead wires 21 and 22 to become fatigued. However, there was a problem that the wire would break. In particular, in this type of electromagnetic acoustic transducer, the wire diameter of the coil 2 is very thin, for example, 0.1 mmφ or less, so when the coil ends are guided outside the case as lead wires 21 and 22, a slight force is applied. If you just touch it, it will easily break.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present invention incorporates an acoustic converter inside the case, and leads the power supply lead wire of the acoustic converter to the outside of the case. The acoustic transducer is characterized in that the lead wire lead-out portion of the case is filled with silicone rubber resin.

Effect Silicone rubber resins exhibit significantly higher elasticity than epoxy resins over a wide temperature range.
For this reason, when silicone rubber resin is filled in the lead wire lead-out portion, the silicone rubber resin elastically expands and contracts as it is pulled by the lead wire in response to thermal shock or thermal cycle fluctuations, etc. Wire breakage accidents are prevented.

Embodiment FIG. 1 is a front sectional view of an acoustic transducer according to the present invention. In the figure, the same reference numerals as in FIG. 2 indicate the same components. In this embodiment, the coil 2 is directly wound around the iron core 3 that is integrally provided on the yoke 4, and the power supply lead wire formed at the coil end of the coil 2 is passed through the opening 41 formed in the yoke 4. 21, 22, case 1
The structure is such that the opening 41 is filled with silicone rubber resin 9 and closed.

The silicone rubber resin 9 is, for example, -40 to +80°C.
It exhibits significantly higher elasticity than epoxy resin over a wide temperature range, so it can withstand thermal shock.
Alternatively, when the ambient temperature fluctuates cyclically, the silicone rubber resin 9 elastically expands and contracts as if being pulled by the lead wires 21 and 22. Therefore, disconnection accidents of the lead wires 21 and 22 are reliably prevented. The same applies when an external force is applied to the lead wires 21 and 22.

When focusing only on the elasticity of the silicone rubber resin, a structure in which the lead wires 21 and 22 are covered with a silicone rubber resin tube and the opening 41 is filled with a conventional epoxy resin or silicone rubber resin, etc., can be considered. In this case, it is necessary to insert the silicone rubber resin into the lead wires 21 and 22, making the assembly work troublesome.
In contrast, in the present invention, it is only necessary to fill the opening 41 with the silicone rubber resin 9, which facilitates assembly and manufacturing work.

Effects of the invention As described above, the present invention has a silicone rubber resin filled in the power supply lead wire lead-out portion of the acoustic transducer built into the case, so that it can be easily tamed by thermal shock or cyclical fluctuations in ambient temperature. , an acoustic transducer capable of absorbing and mitigating the thermal force applied to the silicone rubber resin and the lead wire and the force applied from the outside to the lead wire by the elastic action of the silicone rubber resin, thereby preventing lead wire breakage accidents. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an acoustic transducer according to the present invention, and FIG. 2 is a sectional view of a conventional acoustic transducer. DESCRIPTION OF SYMBOLS 1...Case, 2...Coil, 3...Iron core, 4...Yoke, 5...Permanent magnet, 6...Diaphragm, 9...Silicone rubber resin, 21, 22...Power supply lead wire, 41...
Aperture.

Claims (1)

[Claims for Utility Model Registration] (1) In an acoustic transducer in which an acoustic converter is built into a case and a power supply lead wire of the acoustic converter is led out of the case, the lead wire of the case is An acoustic transducer characterized by having a portion filled with silicone rubber resin. (2) The acoustic transducer excites a diaphragm that is opposed to the magnetic pole of the electromagnet with an air gap interposed therebetween by magnetic interaction between an electromagnet and a permanent magnet, and the power supply lead wire The acoustic transducer according to claim 1, characterized in that the acoustic transducer comprises a coil terminal of an electromagnet. (3) The case has a sound emitting hole on one end side in the axial direction, and has a bottom plate on the opposite side on which the acoustic converter is mounted, and the lead wire is passed through an opening provided in the bottom plate to the case. The acoustic transducer according to claim 1 or 2, wherein the silicone rubber is introduced to the outside and filled in the opening.