Vibrator

Abstract

A vibrator includes a voice coil and a vibrating member that vibrates along the axial direction of the voice coil when it is excited by application of an alternating current thereto. A suspension supports the vibrating member vibratably in the axial direction. A casing houses the voice coil, the vibrating member, and the suspension. A buffering member is provided so that the vibrating member strikes the buffering member when the vibration amplitude of the vibrating member has exceeded a predetermined value in a resonance region around the resonance point of the vibrating member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a vibrator according to a first embodiment of the present invention.

FIG. 1B is a sectional view taken along the line 1B-1B in FIG. 1A.

FIG. 2 is a graph showing the relationship between the frequency and acceleration of the vibrator according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a vibrator according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a vibrator according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a vibrator according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view of a vibrator according to a fifth embodiment of the present invention.

FIG. 7A is a plan view of a first suspension in an embodiment of the present invention.

FIG. 7B is a sectional view taken along the line 7B-7B in FIG. 7A.

FIG. 8A is a plan view of a second suspension in an embodiment of the present invention.

FIG. 8B is a sectional view taken along the line 8B-8B in FIG. 8A.

FIG. 9 is a sectional view of a vibrator according to a sixth embodiment of the present invention.

FIG. 10 is a sectional view of a vibrator according to a related art.

FIG. 11 is a graph showing the relationship between the frequency and acceleration of the vibrator according to the related art.

FIG. 12 is a sectional view of a vibrator according to a seventh embodiment of the present invention.

FIG. 13 is a perspective view of a buffering member used in the vibrator according to the seventh embodiment.

FIG. 14 is a graph showing the results of a simulation analysis to examine the cushioning properties of the buffering member used in the vibrator according to the seventh embodiment and buffering members used in other embodiments.

Claims

1. A vibrator comprising: a voice coil;a vibrating member that vibrates along an axial direction of said voice coil when said voice coil is excited by application of an alternating current thereto;a suspension that supports said vibrating member vibratably in said axial direction;a casing that houses said voice coil, said vibrating member and said suspension; anda buffering member provided so that said vibrating member strikes said buffering member when a vibration amplitude of said vibrating member has exceeded a predetermined value in a resonance region around resonance point of said vibrating member.

2. A vibrator according to claim 1, wherein said buffering member is fixed to said casing.

3. A vibrator according to claim 1, wherein said buffering member is fixed to said vibrating member.

4. A vibrator according to claim 1, wherein said buffering member is fixed to each of said casing and vibrating member.

5. A vibrator according to claim 1, wherein said vibrating member and said buffering member have respective surfaces that strike each other when a vibration amplitude of said vibrating member has exceeded said predetermined value, at least one of said surfaces having a plurality of projections extending toward the other of said surfaces.

6. A vibrator according to claim 5, wherein said buffering member is made from silicone rubber.

7. A vibrator according to claim 5, wherein said buffering member is made from a foam material.

8. A vibrator according to claim 7, wherein said buffering member is made from a microcellular polymer.

9. A vibrator according to claim 1, wherein said suspension has a first and a second suspensions that support said vibrating member from both sides thereof in said axial direction.

10. A vibrator according to claim 1, wherein said casing comprises: a cup-shaped member having a tubular portion coaxial with respect to said voice coil, a bottom wall portion that closes one end of said tubular portion, and an opening at the other end of said tubular portion; anda circular base plate that closes the opening of said cup-shaped member and that supports said voice coil, said base plate having wiring for supplying an input signal to said voice coil;wherein said buffering member is mounted on said base plate so as to face said vibrating member inside said voice coil, and a space a between said buffering member and said vibrating member in said axial direction and a space b in said axial direction between said vibrating member and said bottom wall of said casing satisfy a relationship of b≧1.2×a.