Electromagnetic sound generator

Details Electromagnetic sound generator Electromagnetic sound generator

2001-03-23

2002-08-13

Trieu, Van (Department: 2632)

Communications: electrical

Audible indication

Diaphragm

C340S388100, C340S388500

Reexamination Certificate

active

06433674

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic sound generator, and more particularly to a vibrating plate of the sound generator.
In recent years, surface mount technology has been developed where electronic parts are directly mounted on a printed circuit board. The electromagnetic sound generator used in the portable telephone and beeper is also mounted on the circuit board.
FIG. 5
is a plan view of a conventional electromagnetic sound generator in which upper parts thereof are removed along a line V—V of FIG.
6
.
FIG. 6
is a sectional view taken along a line VI—VI of
FIG. 5
, and
FIGS. 7
a
and
7
b
are sectional views of a vibrating plate of the sound generator.
Referring to
FIG. 5
, a case
50
of the electromagnetic sound generator comprises a lower case
51
and an upper case
52
. A pair of cylindrical holes
51
b
are formed in the lower case
51
, and an annular projection
51
a
is formed on the lower case
51
.
A yoke
53
made of magnetic material is mounted on the bottom of the lower case
51
. A core
53
a
is formed on the surface of the yoke
53
and a notch
53
b
is formed in the yoke
53
. An annular magnet
55
and a coil
54
are mounted on the yoke
53
. A circular vibrating plate
56
is secured on the annular projection
51
a
. An armature
57
comprising a circular magnetic plate is secured to the vibrating plate
56
at the central portion thereof so as to oppose to the core
53
a
. Thus, a magnetic circuit for a buzzer is formed by the yoke
53
, core
53
a
, magnet
55
and vibrating plate
56
.
A pair of lead plates
58
, each of which is made of an elongated metal plate, are embedded in the lower case
51
. Each of the lead plates
58
is extended between the upper end of the hole
51
b
and an end
58
a
in the notch
53
b
of the yoke
53
. A coil spring
59
is inserted in each hole
51
b
. An upper end of the coil spring
59
is inserted in a hole
58
c
formed in an end portion
58
b
of the lead plate
58
and electrically connected to the lead plate
58
by solder. The lower end of the spring
59
is projected from the lower case
51
. The upper case
52
is adhered to the lower case
51
so that a sound emanating hole
50
a
is formed between the upper case
52
and the lower case
51
.
When a signal current flows in the coil
54
passing through springs
59
and lead plates
58
, the coil
54
is excited to attract the armature
57
. Thus, the armature
57
is vibrated to produce sounds which emanate from the sound emanating hole
50
a.
As shown in
FIG. 7
a
, the armature
57
is a flat magnetic plate formed by stamping out a flat material plate. When the armature
57
is attracted to the core
53
a
, the vibrating plate
56
is bent as shown in
FIG. 7
b
. As a result, there occurs stress concentration along the peripheral edge of the armature
57
. The concentrated stress restrains the vibrating plate
56
from vibrating, which causes the vibration to be unstable.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electromagnetic sound generator in which a vibrating plate may be stably vibrated without stress concentration, thereby providing a stable sound emanating characteristic.
According to the present invention, there is provided an electromagnetic sound generator comprising a case, an electromagnet having a vibrating plate mounted in the case, an armature secured on the vibrating plate, wherein the armature having a concave spherical shape, and secured to the vibrating plate at a central portion thereof.
The armature has a uniform thickness.
The armature has a radius curvature so that a peripheral edge of the armature does not contact with the vibrating plate when the vibrating plate is vibrated at a maximum amplitude.
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: 4763109 (1988-08-01), Smith
patent: 5524061 (1996-06-01), Mooney et al.
patent: 5841343 (1998-11-01), Hapke et al.
patent: 6291915 (2001-09-01), Yamaguchi

Affiliated with

Also associated with

Rating

Electromagnetic sound generator does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electromagnetic sound generator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic sound generator will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2900481