Speaker for an electronic instrument

Details Speaker for an electronic instrument Speaker for an electronic instrument

2002-02-08

2003-12-09

Harvey, Minsun Oh (Department: 2644)

Electrical audio signal processing systems and devices

Having non-electrical feature

C381S391000, C381S189000

Reexamination Certificate

active

06661898

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a speaker for an electronic instrument such as a portable telephone.
In recent years, there is used a thin electrodynamic speaker having an excellent quality for the portable telephone. Dimensions of parts in the speaker, in particular, position accuracy of the voice coil disposed in the magnetic circuit have an influence on sound quality. Therefore, it is necessary to severely check the position accuracy.
A conventional speaker will be described hereinafter with reference to
FIGS. 4 and 5
.
The speaker comprises a lower frame assembly
51
and an upper frame assembly
52
.
The lower frame assembly
51
comprises an annular lower frame
61
made of plastic, a tray shape yoke
62
made of magnetic material and embedded in the lower frame, a permanent magnet
63
secured to the yoke and a top plate
64
made of magnetic material and secured to the permanent magnet
63
. A magnetic circuit is formed by the top plate
64
, permanent magnet
63
and the yoke
62
to form a magnetic gap
66
between the peripheral wall of the top plate
64
and the inside wall of an upper portion of the yoke
62
.
On the upper surface of the lower frame
61
, an annular projection
61
a
is formed at a peripheral portion thereof and an annular step
61
b
is formed outside the projection
61
a.
The upper frame assembly
52
comprises an annular upper frame
71
made of plastic, a diaphragm
73
, a voice coil
74
secured to the underside of the diaphragm
73
, and a protector
75
having a plurality of sound discharge openings. A pair of leads
72
are embedded in the upper frame
71
and projected from the upper frame and downwardly bent.
The upper frame
71
has an annular upper step
71
a
on the upper surface thereof, and an annular lower step
71
b
. The diaphragm
73
is adhered to the lower step
71
b
and the protector
75
is adhered to the upper step
71
a.
Both ends
74
a
of the voice coil
74
are projected from the upper frame
71
passing through holes formed in the frame and connected to the leads
72
, respectively.
FIG. 5
shows both the lower and upper frame assemblies
51
and
52
.
The upper frame
71
is secured to the step
61
b
of the lower frame
61
by the ultrasonic welding, so that the voice coil
74
is disposed in the magnetic gap
66
.
In order to allow the vibration of one of the frame assemblies in the ultrasonic welding operation, there is provided a clearance B between the inside wall of the upper frame
71
and the outside wall of the projection
61
a
of the lower frame
61
. However, the clearance (0.05-0.1 mm) causes central positions of the lower and upper frames
61
and
71
to deviate from each other when both frame assemblies are coupled with each other. As a result, the position of the voice coil
74
is not accurately positioned in the magnetic gap
66
, so that the sound quality of the speaker deteriorates.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a speaker in which the voice coil can be accurately positioned in the magnetic gap.
According to the present invention, there is provided a speaker for an electronic instrument comprising a lower frame assembly comprising a lower frame provided with a yoke, a permanent magnet secured to the yoke, and a top plate secured to the permanent magnet, an upper frame assembly comprising an upper frame provided with a diaphragm secured to the upper frame, and a voice coil secured to the diaphragm and disposed in a magnetic gap between the yoke and the top plate, wherein a plurality of grooves are formed in a peripheral wall of the lower frame, a plurality of engaging portions are formed on the upper frame, corresponding to the grooves of the lower frame, each of the engaging portions comprises an engaging plate and a hook formed at an end of the engaging plate.
Each of the engaging portions comprises an elastic engaging plate axially projected from an underside of the upper frame, and a hook formed at an end of the elastic engaging plate so as to be engaged with an underside of the lower frame.
These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.


REFERENCES:
patent: 5181253 (1993-01-01), Jordan
patent: 6404896 (2002-06-01), Yoo

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