Vibration speaker

Details Vibration speaker Vibration speaker

2001-05-01

2004-05-18

Ni, Suhan (Department: 2643)

Electrical audio signal processing systems and devices

Electro-acoustic audio transducer

Electromagnetic

C381S431000, C340S407100

Reexamination Certificate

active

06738489

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates a vibration speaker installed in a communication appliance such as a cellular phone and adapted to conduct both the function for generating sound and the function for generating vibrations. More particularly, the present invention relates to a vibration speaker capable of applying upward and downward damping forces to a vibrating body, thereby reducing a variation in the amplitude of vibrations depending on a variation in frequency to obtain an improvement in vibration characteristics.
2. Description of the Related Art
Generally, a speaker is a sound generating device for outputting an audible sound corresponding to an audio signal electrically or electronically received or a bell or melody previously inputted.
Typically, such a speaker is connected to an audio appliance or amplifier so that it serves as a large-size sound generating means adapted to greatly amplify the amplitude of sound. Alternatively, speakers are widely used which have a greatly reduced size so that they are used as miniature sound generating means.
In particular, speakers applied to miniature communication appliances such as cellular phones or pagers have a greatly reduced size. Such speakers are called “micro speakers”
The current tendency of such micro speakers is toward smaller sizes because communication appliances such as cellular phones are currently intended to have a reduced size or thickness.
FIG. 1
is a sectional view illustrating a conventional micro speaker mainly used in portable communication appliances. As shown in
FIG. 1
, the conventional micro speaker includes a housing
100
defined with a space therein. A magnet
110
and a voice coil
120
are arranged in the housing
100
. The micro speaker also includes a vibrating plate
130
for generating a sound.
In the micro speaker having the above mentioned configuration, when a high frequency current supplied from an external current source is applied to the voice coil
120
via a lead
101
, a magnetic field is established in accordance with a cooperation between the voice coil
120
and the magnet
110
, thereby causing the voice coil
120
to move vertically. As a result, the vibrating plate
130
, which is attached to one end of the voice coil
120
, generates a sound while finely vibrating.
The high frequency current applied to the voice coil
120
via the lead
101
is AC. Accordingly, when the magnetic field generated by the voice coil
120
varying in direction in accordance with the direction of the current applied to the voice coil
120
is rendered to correspond to the magnetic field formed by the magnet
110
, a repulsion force is exerted between the magnet
110
and the voice coil
120
, so that the magnet
110
and the voice coil
120
tend to be moved away from each other. As a result, the voice coil
120
is upwardly moved away from the magnet
110
.
On the other hand, when the magnetic field generated by the voice coil
120
has a direction reverse to that of the magnetic field formed by the magnet
110
, an attraction force is exerted between the magnet
110
and the voice coil
120
, so that the magnet
110
and the voice coil
120
tend to be moved toward each other. As a result, the voice coil
120
is downwardly moved toward the magnet
110
.
Thus, the voice coil
120
moves upwardly and downwardly in accordance with a change in direction of the magnetic field generated by the voice coil
120
. By virtue of the alternating upward and downward movements of the voice coil
120
, the vibrating plate
130
attached to the voice coil
120
vibrates upwardly and downwardly. As the vibrations of the vibrating plate
120
is externally emitted, a sound is generated. Thus, the sound generating function is carried out.
Meanwhile, the portable communication appliance also includes a vibrating means adapted to allow the user to recognize a receiving call by vibrations other than sound.
For such a vibrating means, a vibration motor has been mainly used. Recently, a vibration speaker has been developed which is configured by adding a vibrating function to a speaker having a simple sound generating function.
FIG. 2
is a sectional view illustrating a conventional vibration speaker. As shown in
FIG. 2
, the vibration speaker has a configuration including a voice coil adapted to generate sound when it receives a high frequency current, and a vibration coil adapted to generate vibrations when it receives a low frequency current.
In detail, this vibration speaker includes a housing
100
adapted to form a casing and defined with a space having a desired size. A yoke
105
is arranged at the central portion of the space defined in the housing
100
.
A weight
140
fixed to outer surface of the yoke
105
is elastically supported by a pair of vertically spaced plate springs
150
and
155
each fixedly mounted to the inner peripheral surface of the housing at one end thereof. The plate springs
150
and
155
are also mounted to the upper and lower portions of the yoke
105
to support the yoke
105
, respectively.
The upper spring
150
is firmly fitted, at its outer peripheral edge, in a holding groove
100
a
provided at the upper portion of the inner peripheral surface of the housing
100
. The outer peripheral edge of the lower spring
155
is in contact with a step of the housing
100
at its upper surface. The step is formed at the lower portion of the inner peripheral surface of the housing
100
. Under the condition in which the lower spring
155
is in contact with the step, the lower spring
155
is bonded to the housing
100
using an adhesive
100
b
applied between the inner peripheral surface of the housing
100
and the lower surface of the lower spring
155
.
A magnet
110
is attached to the central portion of the yoke
105
. Beneath the magnet
110
, a vibration coil
115
is attached to the upper surface of a lower plate
102
attached to the lower end of the housing
100
.
A vibrating plate
130
adapted to generate sound is mounted to the upper end of the housing
100
. A voice coil
120
extends downwardly from the vibrating plate
130
in such a fashion that it surrounds the magnet
110
.
In order to obtain an increased amplitude of vibrations in the vibration speaker having the above mentioned configuration, a weight
140
, which is a mass body, is arranged in the space defined between the plate springs
150
and
155
.
In the conventional vibration speaker having the above mentioned configuration, when a high frequency signal is applied to the voice coil
120
, the vibrating plate
130
vibrates finely by virtue of electromagnetic forces generated between the voice coil
120
and the magnet
110
, thereby generating sound. This sound is used as a speaker sound.
When a low frequency signal is applied to the vibration coil
115
, the vibrating body moves upwardly and downwardly by virtue of electromagnetic forces generated between the vibration coil
115
and the magnet
110
. This upward and downward movements are transmitted to the housing
100
via the plate springs. Thus, a desired vibration function is carried out.
In the above mentioned conventional vibration speaker, the vibrating body, which is composed of the yoke
105
, the magnet
110
, and the weight
140
, is upwardly and downwardly moved in accordance with a vibration excitement at a desired frequency using the resonant frequency of the vibrating body. Thus, vibrations are generated.
However, this conventional vibration speaker has a disadvantage in that there may be a variation in the amplitude of vibrations due to an assembling dispersion of the yoke
105
, magnet
110
, and weight
140
included in the vibrating body, and that there is a deviation between the designed resonant frequency of the vibrating body and the actual resonant frequency of the vibrating body because a variation in the amplitude of vibrations occurs depending on the dimension dispersion of each element included in the vibration speaker.
Referring to
FIG. 3
, it can be found that the gradient

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