Audio-frequency electromechanical vibrator

DETAILED DESCRIPTION It is an object of this invention to provide an audio frequency electromechanical vibrator which can make strong vibrations.
It is another object of this invention to provide a vibrator which does not vibrate in response to a higher frequency component included in an audio frequency signal applied to the vibrator.
It is still another object of this invention to provide a vibrator with a reduced heat generation.
It is yet another object of this invention to provide a vibrator which is generally flat and compact.
It is another object of this invention to provide a vibrator wherein heat generated is readily diffused.
It is still another object of this invention to provide a vibrator which is simple in construction and assembling operation.
The present invention is an audio-frequency electromechanical vibrator comprising an open-topped case of a magnetic material with a cover plate closing the open end, an annular coil unit for receiving an audio-frequency power signal and being disposed within the case, a ring-shaped permanent magnet being axially magnetized, the ring-shaped magnet disposed coaxial with the annular coil unit and facing the coil unit with an axial space therebetween, and a spring damper means supported in the case and for elastically supporting one of the magnet and the coil unit, the other one being fixedly mounted to an inner bottom of the case.
According to the present invention, a flat and compact vibrator can be obtained by the use of a flat hollow case, a flat coil unit and a flat magnet.
The vibrator can produce strong and neat vibration with a reduced heat generation.
The vibrator according to the present invention can be driven by an audio-frequency signal without the use of a filter for removing a comparatively higher frequency component, because neither coil unit nor magnet is directly connected to a thin cover plate.
In an aspect of the present invention, the case has a central boss portion formed by a central portion of the bottom of the case being inwardly raised