JPH01272294A - Bone conduction microphone - Google Patents

Abstract

PURPOSE:To attain a low cost by one side supporting a piezoelectric bimorph vibrator connected to this preamplifier on a substrate on which the preamplifier is loaded and covering the circumference of the piezoelectric bimorph vibrator by an elastic material. CONSTITUTION:The preamplifier 6 is loaded on the substrate 22, the lead wire is connected thereto, on the substrate 22, the piezoelectric bimorph vibrator 4 is one side supported by a supporting base made of a metal and connected to the preamplifier 6 and the entirety including the circumference of the piezoelectric bimorph vibrator 4 is covered by dipping, potting and molding, etc., by the use of the elastic material 26 such as silicone rubber. This elastic material 26 may cover at least the circumference of the piezoelectric bimorph vibrator 4 in view of a damping. Thereby, since it has a simpler structure and is excellent in mass production, low cost is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bone conduction microphone using a piezoelectric bimorph vibrator.

[Conventional technology]

Bone conduction microphones pick up the vibrations of the vocal cords that have propagated to the skull from the nasal bones, etc., and are used as hidden microphones for police, defense, etc., or in noisy environments (construction sites, factories, etc.).
It has been put into practical use as a microphone at tourist spots, etc.

A conventional example of such a bone conduction microphone is shown in FIG.

That is, this bone conduction microphone 2 houses a piezoelectric bimorph vibrator 4 and a preamplifier 6 connected to it in a metal pipe 12, draws out a lead wire 8, and supports the piezoelectric bimorph vibrator 4 in a cantilever manner by a resin 10 or the like. , a damper oil 14 is filled around the piezoelectric bimorph vibrator 4 so as to obtain the required characteristics as a microphone, and the exterior is covered with a heat shrink tube 18. 16 is an oil seal.

Such a bone conduction microphone 2 is used by being attached to, for example, glasses, and when vibrations from the vocal cords are transmitted to it, a corresponding voltage is generated in the piezoelectric bimorph vibrator 4, which is amplified by a preamplifier 6 and sent to the lead. It is taken out to the outside through cotton 8.

Problems to be Solved by the Invention C] However, the conventional bone conduction microphone 2 as described above has a complicated structure and is not suitable for mass production, resulting in high costs.

Therefore, the main object of the present invention is to provide a bone conduction microphone that has improved on these points.

[Means to solve the problem]

The bone conduction microphone of the present invention cantilever-supports a piezoelectric bimorph vibrator connected to the preamplifier on a substrate mounted with a preamplifier, and covers at least the circumference of the piezoelectric bimorph vibrator with an elastic material. Features.

[Effect]

According to the above structure, appropriate damping can be applied to the vibrating portion of the piezoelectric bimorph vibrator using the elastic material, so that the required characteristics as a microphone can be obtained.

〔Example〕

FIG. 1 is a schematic cross-sectional view showing a bone conduction microphone according to an embodiment of the present invention.

The bone conduction microphone 20 of this embodiment has a amplifier 6 including an FET, a resistor, etc. mounted on a substrate 22 made of glass epoxy, alumina, etc., and a lead wire 8 such as a shield wire connected thereto. The piezoelectric bimorph vibrator 4 is cantilever-supported on the substrate 22 by a metal support 24, and is connected to the preamplifier 6. In this example, the entire piezoelectric bimorph vibrator 4 including its surroundings is made of silicone rubber or the like. It is covered with an elastic material 26 by dipping, botting, molding, etc. However, this elastic material 26 only needs to cover at least the circumference of the piezoelectric bimorph vibrator 4 in terms of damping, which will be described below.

According to the above structure, appropriate damping can be applied to the vibrating portion of the piezoelectric bimorph vibrator 4 by the elastic material 26, so that the required characteristics (sensitivity, etc.) as a microphone can be obtained.

Moreover, compared to the conventional example, the metal pipe 12 and oil seal 16 for confining the damper oil 14 are not required, and the structure is simple and excellent in mass production.
It can be made at low cost. Moreover, it can also be made small.

The reason why the support base 24 is made of metal is that it can also serve as an electrical connection between the electrode 4a of the piezoelectric bimorph vibrator 40 on the lower side in the diagram and the preamplifier 6.

Further, by connecting the upper electrode 4a of the piezoelectric bimorph vibrator 4 in the figure and the grounding electrode 22a on the surface of the substrate 22 to the grounding side of the lead wire 8, it is possible to provide shielding properties against noise, etc. can. This ground electrode 22a may be provided on the back side of the substrate 22, in which case it can be provided on the entire surface and the entire surface can be shielded, so that the shielding effect can be further enhanced.

Also, if the shield is insufficient even after doing the above,
Like the bone conduction microphone 30 shown in FIG.
6 is covered with a conductive material 32 such as conductive rubber or conductive resin,
This conductive material 32 may also be grounded, and in this way the shielding effect can be easily increased.

Furthermore, as in a bone conduction microphone 30 shown in FIG. 2, the outside of the conductive material 32 may be further covered with a resin 34 to provide an exterior. Furthermore, such an exterior with resin 34 may be applied to the bone conduction microphone 20 shown in FIG. 1.

Furthermore, the bone conduction microphone 20 or 30 as described above, before or after being covered with the resin 34, can be made smaller, for example, as shown in FIG. It is also possible to integrally mold the earmuff resin part 44 of the frame 42 (if this is done, the bone conduction microphone 20 (30) will not be noticeable at all, and its lead wire 8 will also become inconspicuous, which is very convenient for use. becomes convenient.

In that case, the metal part of the frame 42 may be connected to the ground part of the bone conduction microphone 20 (30) and used as a shield plate.

〔Effect of the invention〕

As described above, the bone conduction microphone of the present invention has a simpler structure and is easier to mass produce than conventional ones, so it can be manufactured at a lower cost. Moreover, it can also be made small.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a bone conduction microphone according to an embodiment of the present invention. FIG. 2 is a schematic sectional view showing a bone conduction microphone according to another embodiment of the invention. FIG. 3 is a perspective view showing an example in which the bone conduction microphone of FIG. 1 or 2 is attached to glasses. FIG. 4 is a schematic cross-sectional view showing an example of a conventional bone conduction microphone. 4...Piezoelectric bimorph resonator, 6...Preamplifier,
8... Lead wire, 20.30... Bone conduction microphone according to the example, 22... Substrate, 24... Support stand,
26... Elastic material, 32... Conductive material, 34... Resin.

Claims (1)

[Claims] (1) A bone conductor characterized in that a piezoelectric bimorph vibrator connected to the preamplifier is cantilever-supported on a board on which a preamplifier is mounted, and at least the piezoelectric bimorph vibrator is covered with an elastic material. Microphone.