Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – With magneto-mechanical motive device
Reexamination Certificate
2002-07-09
2003-08-19
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
With magneto-mechanical motive device
C335S223000, C340S007600, C340S407100, C381S401000, C381S402000
Reexamination Certificate
active
06608541
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic actuator, and more particularly, to an electromagnetic actuator used for mobile phones, beepers and so on for making a call at the time of signal arrival by sound or vibration.
2. Description of the Related Art
A first electromagnetic actuator disclosed in WO No. 39843/1999 is well known as this type of electromagnetic actuator. The first electromagnetic actuator is shown in FIG.
6
. As shown in
FIG. 6
, an electromagnetic actuator
100
includes a magnet
105
in a groove of a yoke
103
in a case
101
and a coil
109
mounted to a diaphragm
107
in the groove with a gap provided between it and the magnet
105
. The yoke
103
is supported by upper and lower vibration plates
111
and
113
arranged in parallel on the side of the case
101
. By applying a low-frequency current to the coil
109
, the yoke
103
vibrates by the action of the vibration plates
111
and
113
, and by applying a high-frequency current to the coil
109
, the diaphragm
107
vibrates to generate a high-frequency sound. Also, a collar
115
projects from the case
101
in the radial direction for regulating the vibration direction of the yoke
103
in the vertical direction.
A second electromagnetic actuator of the same type uses two coils for driving, which is shown in FIG.
7
. As shown in
FIG. 7
, an electromagnetic actuator
200
includes a vibration coil
203
and a voice coil
205
. The vibration coil
203
is secured to the upper collar of a case
213
and is disposed in an external gap formed between a pole piece
209
and the external wall of a yoke
210
. The voice coil
205
is secured to a diaphragm
223
and is disposed in an inner gap formed between the pole piece
209
and the inner wall of the yoke
210
.
An upper leaf spring
217
a
is interposed between the external wall of the yoke
210
and the upper collar of the case
213
; and a lower leaf spring
217
b
is interposed between the bottom of the yoke
210
and a cover
214
and is compressed from a natural position to support the yoke
210
by sandwiching it from above and below.
A ring-shaped magnet
207
has a pole piece
209
bonded to the top thereof, the bottom of which is secured to the concave portion of the yoke
210
, and the yoke
210
, the magnet
207
, and the pole piece
209
form a vibration body in which the total mass thereof is supported by the spring constant of the leaf springs
217
a
and
217
b
. A direction regulating member
241
projecting from a central yoke of the cover
214
acts as a shaft for regulating the movement of the yoke
210
only in a vertical direction.
When a low-frequency current is applied to the vibration coil
203
from a terminal block
213
c
, the yoke
210
vibrates and, when a high-frequency current is applied to the voice coil
205
, the diaphragm
223
vibrates to generate a high-frequency sound.
Furthermore, there is a third electromagnetic actuator of the same type using two coils, which is shown in FIG.
8
. As shown in
FIG. 8
, in a third electromagnetic actuator
300
, pole pieces
309
a
and
309
b
bonded to the top and the bottom of a magnet
307
, respectively, face a yoke
310
; a vibration coil
303
is disposed in a lower gap portion and a voice coil
305
is disposed in an upper gap portion; and the yoke
310
is sandwiched by two leaf springs
317
a
and
317
b.
A case
313
supports the leaf springs
317
a
and
317
b
with the inner periphery thereof, and supports a peripheral yoke of a diaphragm
323
. The case
313
supports the vibration coil
303
and also supports the magnet
307
and the pole pieces
309
a
and
309
b
with a support base
315
.
When a low-frequency current is applied to the vibration coil
303
from a terminal block
313
c
, the yoke
310
vibrate and, when a high-frequency current is applied to the voice coil
305
, the diaphragm
323
vibrates to generate a high-frequency sound. Referring to
FIG. 8
, there is also provided a configuration in which a vertical midpoint of the yoke
310
and a vertical midpoint of the magnet
307
are connected with a ring-shaped arm (not shown) and the support base
315
is eliminated. With such a configuration, since the total math of the yoke
310
, the magnet
307
, and the pole pieces
309
a
and
309
b
acts as a vibration body, thus increasing vibration.
Also, referring to
FIG. 8
, there is also provided a configuration in which the yoke
310
is replaced with a combination of the ring-shaped magnet
307
and the pole pieces
309
a
and
309
b
, and the combination of the magnet
307
and the pole pieces
309
a
and
309
b
is replaced with the yoke
310
. With such a configuration, the volume of the magnet
307
can be increased.
However, the art shown in
FIG. 6
has problems in that since the collar
115
for regulating the direction of vibration is brought into contact with the yoke
103
, stable vibration is lost, and that when a high-frequency current is applied to the coil
109
during the vibration of the yoke
103
, distortion of a high-frequency sound is caused owing to a low-frequency vibration.
Also, the arts shown in
FIGS. 7 and 8
have a problem in that when a low-frequency current is applied to the vibration coils
203
and
303
, the yokes
210
and
310
vibrate and gaps in which the voice coils
205
and
305
are positioned also vibrate, and accordingly, when the simultaneous generation of a low-frequency vibration and a high-frequency sound is intended, distortion of the high-frequency sound is caused because of the low-frequency vibration.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a compact electromagnetic actuator capable of generating a high-frequency sound without distortion while ensuring stable vibration even during low-frequency vibration.
In order to achieve the above object, an electromagnetic actuator according to a first aspect of the present invention comprises a magnet; a pole piece mounted to the magnet; a yoke facing the pole piece; a coil base having a vibration coil facing the pole piece; a leaf spring for supporting the coil base and a weight disposed around the periphery of the yoke; a case for enclosing them; a cover for covering one side of the case; and a diaphragm having a voice coil, wherein arms of the coil base are inserted through notches formed in the yoke to allow the vibration coil and the voice coil to be disposed in a gap in which the pole piece and the yoke face each other; the weight vibrates by the application of a low-frequency current to the vibration coil; and the diaphragm vibrates by the application of a high-frequency current to the voice coil facing the pole piece.
In this invention, since the voice coil is positioned in a gap sandwiched by the fixed pole piece and the yoke, it can generate sound without the influence of vibration even during the vibration of the weight.
According to the present invention, preferably, in the above invention, the pole piece is composed of two pole pieces mounted on the top and the bottom of the magnet; the vibration coil is disposed in a lower gap portion in which the pole piece and the yoke face each other; and the voice coil is disposed in an upper gap portion.
This invention has similar advantages to those of the above invention and, since the vibration coil is disposed in the lower gap portion, induced interference between both coils can be reduced.
According to the present invention, preferably, in the above invention, the vibration coil and the voice coil are concentrically disposed in the gap in which the pole piece mounted on the top of the magnet and the yoke face each other.
This invention has similar advantages to those of the above invention and, since only one gap is formed, leakage flux can be reduced.
According to the present invention, preferably, in either of the above inventions, the leaf spring, which is composed of two leaf springs arranged close to each other, supports only one side of the weight.
This invention has similar ad
Fujii Makoto
Okubo Katsu
Sekiguchi Naoki
Shiraki Manabu
Washio Noriyuki
Barrera Ramon M.
Lorusso, Loud & Kelly
Shicoh Engineering Co. Ltd.
LandOfFree
Electromagnetic actuator 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 actuator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic actuator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3096198