Information
-
Patent Grant
-
6834114
-
Patent Number
6,834,114
-
Date Filed
Tuesday, January 8, 200222 years ago
-
Date Issued
Tuesday, December 21, 200419 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Dennison, Schultz, Dougherty & MacDonald
-
CPC
-
US Classifications
Field of Search
US
- 381 162
- 381 163
- 381 165
- 381 182
- 381 396
- 381 417
- 310 27
- 310 80
- 310 81
-
International Classifications
-
Abstract
A rotor having a yoke is rotatably supported in a frame, and a stator provided in the frame at a central portion of the frame. An annular first permanent magnet is provided on the yoke, and an annular second permanent magnet is provided on the yoke. A diaphragm is supported in the frame, and a voice coil is secured to the diaphragm and inserted in a gap formed by the first permanent magnet. At least two coils are provided on the stator for forming magnetic fluxes between the rotor and the stator so as to rotate the rotor.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a multifunction acoustic device used in a portable instrument such as a portable telephone.
There has been provided an acoustic device of the portable instrument in which a speaker is provided for generating sounds of calling signals, and a vibrating motor is provided for informing the receiver of calling signals without generating sounds. In such a device, since both of the speaker and the motor are mounted in the device, the device is increased in size and weight, and in manufacturing cost.
In recent years, there is provided a multifunction acoustic device in order to remove the above described disadvantages. The multifunction acoustic device comprises a speaker having a vibrating plate and a permanent magnet magnetically connected to a voice coil mounted on the vibrating plate of the speaker. The permanent magnet is independently vibrated at a low frequency of 100-150 Hz so as to inform the receiving of calling signals by the vibration of the case of the device, which is transmitted to the body of the user of the device.
FIG. 7
is a sectional view of a conventional electromagnetic induction converter disclosed in Japanese Utility Model Application Laid Open 5-85192. The converter comprises a diaphragm
506
mounted in a case
512
at a periphery thereof, a voice coil
508
secured to the underside of a central portion
507
of the diaphragm
506
, a spring plate
511
mounted in the case
512
, and a permanent magnet
510
secured to a central portion of the spring plate
511
, inserted in the voice coil
508
.
By applying a low or high frequency signal to the voice coil
508
, the spring plate
511
is vibrated in the polarity direction Y of the magnet
510
.
In the device, the diaphragm
506
and the spring plate
511
are relatively moved through the magnetic combination between the voice coil
508
and the magnet
510
. Consequently, when a low frequency signal or a high frequency signal is applied to the voice coil
508
, both of the diaphragm
506
and the spring plate
511
are sequentially vibrated. As a result, sounds such as voice, music and others generated from the device are distorted, thereby reducing the quality of the sound. In addition, vibrating both of the voice coil
508
and the magnet
510
causes the low frequency vibration of the magnet to superimpose on the magnetic combination of the voice coil
508
and the magnet
510
, which further largely distorts the sounds.
FIG. 8
is a sectional view showing a conventional multifunction acoustic device. The device comprises a speaker vibrating plate
603
made of plastic and having a corrugated periphery
603
a
and a central dome, a voice coil
604
secured to the underside of the vibrating plate
603
at a central portion, and a magnet composition
610
. The vibrating plate
603
is secured to a frame
609
with adhesives.
The magnetic composition
610
comprises a lower yoke
605
, a core
601
formed on the yoke
605
at a central portion thereof, an annular permanent magnet
602
mounted on the lower yoke
605
, and an annular upper yoke
606
mounted on the permanent magnet
602
. The lower yoke
605
and the upper yoke
606
are resiliently supported in the frame
609
by spring plates
607
and
608
. A magnetic gap
611
is formed between a periphery
601
a
of the core
601
and an inside wall
606
a
of the upper yoke
606
to be magnetically connected to the voice coil
604
.
When an alternating voltage is applied to the voice coil
604
through input terminals
612
a
and
612
b
, the speaker vibrating plate
603
is vibrated in the direction Y to generate sounds at a frequency between 700 Hz and 5 KHz. If a low frequency signal or a high frequency signal is applied to the voice coil
604
, the speaker vibrating plate
603
and the magnetic composition
610
are sequentially vibrated, since the magnetic composition
610
and the speaker vibrating plate
603
are relatively moved through the magnetic combination of the voice coil
604
and the magnet composition
610
.
As a result, sounds such as voice, music and others generated from the device are distorted, thereby reducing the quality of the sound. In addition, the driving of both the voice coil
604
and the magnetic composition
610
causes the low frequency vibration to superimpose on the magnetic combination of the voice coil
604
and the magnetic composition
610
, which further largely distorts the sounds.
FIG. 9
is a sectional view showing another conventional multifunction acoustic device. The device comprises the speaker vibrating plate
603
made of plastic and having the corrugated periphery
603
a
and the central dome, the voice coil
604
secured to the underside of the vibrating plate
603
at a central portion, and the magnet composition
610
. The vibrating plate
603
is secured to the frame
609
with adhesives.
The magnetic composition
610
comprises a lower yoke
703
, core
601
formed on the yoke
703
at a central portion thereof, an annular permanent magnet
702
secured to the lower yoke
703
, and annular upper yoke
606
having a peripheral wall
606
b
and mounted on the permanent magnet
702
. The upper yoke
606
is resiliently supported in the frame
609
by spring plates
707
and
708
. A first magnetic gap
701
is formed between a periphery
601
a
of the core
601
and an inside wall of the upper yoke
606
to be magnetically connected to the voice coil
604
. A second gap
705
is formed between a periphery
703
a
of the lower yoke
703
and inside wall
606
a
of the upper yoke
606
. A driving coil
706
is secured to the frame and inserted in the second gap
705
.
When an alternating voltage is applied to the voice coil
604
through input terminals
612
a
and
612
b
, the speaker vibrating plate
603
is vibrated in the direction Y to generate sounds at a frequency between 700 Hz and 5 KHz. If a low frequency signal or a high frequency signal is applied to the voice coil
604
, the speaker vibrating plate
603
and the magnetic composition
610
are sequentially vibrated, since the magnetic composition
610
and the speaker vibrating plate
603
are relatively moved through the magnetic combination of the voice coil
604
and the magnet composition
610
.
When a high frequency signal for music is applied to the voice coil
604
, only the speaker vibrating plate
603
is vibrated. Therefore, there does not occur distortion of the sound. Furthermore, when a low frequency signal is applied to the driving coil
706
, only the magnetic composition
610
is vibrated, and the speaker vibrating plate
603
is not vibrated.
However if a high frequency signal is applied to input terminals
612
a
,
612
b
, and a low frequency signal is also applied to input terminals
704
a
,
704
b
, the speaker vibrating plate
603
and magnetic composition
610
are sequentially vibrated, thereby reducing the sound quality.
In the above described conventional devices, both the speaker vibration plate and the magnetic composition are vibrated when a low frequency signal or a high frequency signal is applied to the voice coil. This is caused by the reason that the low frequency vibrating composition is vibrated in the same direction as the high frequency vibrating direction.
Furthermore, in recent years, electric power for operating the portable telephone increases, which causes increase of the temperature of the coil for vibrating the yoke.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a multifunction acoustic device in which a vibrating member is not vibrated together with another vibrating member, thereby removing disadvantages of conventional devices.
Another object of the present invention is to provide an acoustic device which may reduce the temperature of the coil.
According to the present invention, there is provided a multifunction acoustic device comprising a frame, a rotor having a yoke and rotatably supported in the frame, a stator provided in the frame at a central portion of the frame, an annular first permanent magnet provided on the yoke, an annular second permanent magnet provided on the yoke, a diaphragm supported in the frame, a voice coil secured to the diaphragm and inserted in a gap formed by the first permanent magnet, at least two coils provided on the stator for forming magnetic fluxes between the rotor and the stator so as to rotate the rotor.
The rotor is rotatably mounted on the frame by a central shaft.
An eccentric means is provided on the rotor for vibrating the rotor during the rotation of the rotor.
The stator comprises a spider having a hub and a plurality of spokes.
The coils are provided on spokes of the spider.
The yoke has a central upward cylindrical portion, and the stator is disposed in the cylindrical portion.
The eccentric means is a weight eccentrically provided in the rotor.
An annular top yoke is mounted on the first permanent magnet for forming the gap between the top yoke and the cylindrical portion of the yoke.
A driving circuit is provided for energizing the coils for rotating the rotor.
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.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1
is a sectional view of a multifunction acoustic device of the present invention;
FIG. 2
is a sectional view taken along a line II—II of
FIG. 1
;
FIG. 3
is an exploded perspective view of a rotor of the multifunction acoustic device of the present invention;
FIG. 4
is a plan view of a stator of the multifunction acoustic device of the present invention;
FIG. 5
is a sectional view showing a blade of a cooling fan;
FIG. 6
is a driving circuit used in the multifunction acoustic device of the present invention;
FIG. 7
is a sectional view of a conventional electromagnetic induction converter;
FIG. 8
is a sectional view showing a conventional multifunction acoustic device; and
FIG. 9
is a sectional view showing another conventional multifunction acoustic device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to
FIGS. 1 and 2
, the multifunction acoustic device of the present invention comprises a sound generating device
10
, a rotor
20
and an annular stator
30
provided in a cylindrical frame
1
made of plastic. The sound generating device
10
comprises a speaker diaphragm
14
having a central dome
14
a
and secured to the frame
1
at a periphery
14
b
with adhesives, a voice coil
15
secured to the underside of the speaker diaphragm
14
. The speaker diaphragm
14
is covered by a cover
13
having a plurality of sound discharge holes and secured to the frame
1
at a peripheral edge thereof.
The rotor
20
comprises a rotor yoke
23
having a central upward cylindrical portion
23
a
which is secured to a rotor shaft
16
. The rotor shaft
16
is rotatably supported by bearings
22
a
and
22
b
secured to a base plate of the frame
1
by a cylinder
26
, interposing an oil absorbing member
24
so that the rotor yoke
23
is rotatably mounted on the frame
1
. An annular speaker permanent magnet
17
is secured to an annular flat portion of the rotor yoke
23
extending from and around the cylindrical portion
23
a
, and an annular top yoke
18
is secured on the magnet
17
. The speaker permanent magnet
17
is magnetized in the same polarity in the axial direction at circumferential positions. Thus, a first magnetic circuit is formed between the top yoke
18
and the cylindrical portion
23
a
of the yoke
23
.
An annular rotor permanent magnet
21
is secured to the inside wall of the cylindrical portion
23
a
. As shown in
FIG. 3
, the rotor permanent magnet
21
is magnetized in eight polarities at eight circumferential positions. Thus, a second magnetic circuit is formed between the rotor
20
and the stator
30
. The voice coil
15
is disposed in a speaker gap
11
formed between the inside wall of the top yoke
18
and the outside wall of the cylindrical portion
23
a
of the yoke
23
.
As shown in
FIGS. 2 and 3
, a semicircular weight
25
made of plastic including heavy particles such as tungsten particles is secured to the outside wall of the speaker magnet
17
and mounted on the rotor yoke
23
. As another means, the permanent magnet
17
may be eccentrically disposed with respect to the rotor shaft
16
. A motor gap
12
is formed between the inside wall of the rotor permanent magnet
21
and the stator
30
. As shown in
FIG. 3
, a cooling fan
27
is provided on the top plate of the cylindrical portion
23
a
for cooling the stator
30
. Each blade
27
a
is formed by cutting the top plate and downwardly bending as shown in FIG.
5
.
In addition, a plurality of projections
28
are formed on the inside wall of the top yoke
18
for cooling the voice coil
15
. Further, a plurality of heat discharge holes
29
are formed in the yoke
23
for discharging air heated by the voice coil
15
.
Referring to
FIG. 4
, the stator
30
comprises a spider having an annular hub
31
and eight spokes
32
radially projected from the hub
31
, and a stator coil
33
wound on each spoke
32
. The hub
31
is secured to the cylinder
26
. The coils
33
are connected with each other so as to be excited in different polarities.
In order to improve the starting of rotation of the rotor
20
, it may be preferable to change the length L of the spokes
32
.
Thus, the rotor
20
and stator
30
are composed in a synchronous motor. It will be understood that the motor can be made into a stepping motor
Referring to
FIG. 6
, a rotor driving circuit
40
comprises a pair of NPN transistors
41
and
43
and a pair of PNP transistors
42
and
44
which are connected crosswise, interposing the stator coil
33
. Bases of the transistors
41
and
42
are connected to an input terminal
48
, bases of the transistors
43
and
44
are connected to the input terminal
48
through an inverter
47
.
In operation, when a high frequency signal is applied to input terminals
19
a
and
19
b
(
FIG. 1
) of the voice coil
15
, the speaker diaphragm
14
is vibrated in the Y direction (
FIG. 1
) to generate sounds.
When a low frequency signal of about 100-300 Hz is applied to input terminal
48
of the driving circuit
40
, the transistors
41
and
44
are turned on at a high level of the input signal. Consequently, a current passes the stator coils
33
through the transistors
41
and
44
from the Vcc to GND. And the current passes through the transistor
43
, coils
33
in different polarities. Thus, the rotor
20
is rotated at the driving low frequency. Since the weight
25
is eccentrically mounted on the rotor
20
, the rotor vibrates in radial direction. The vibration is transmitted to user's body through the frame
1
and a case of the device so that a calling signal is informed to the user.
On the other hand, the cooling fan
27
cools the coils
33
, and the projections
28
cool the voice coil
11
. Furthermore, the heat of the voice coil
11
is discharged passing through the holes
29
.
The number N of rotation of the rotor is expressed as follows.
N
=60
f/P
(
rpm
) 1
where P is the number of poles of the rotor,
f is driving frequency.
The load torque TL is expressed as follows.
TL=μrRω
2
M
(
N·m
) 2
where M is the mass of weight
25
of the rotor,
R is the length between the center of the rotor shaft
16
and the center of gravity of the weight
25
,
r is the radius of the rotor shaft
16
,
μ is the friction coefficient between the rotor shaft
16
and the rotor
20
,
ω is the number of rotation (rad/sec) of the rotor
20
.
Since the rotor
20
merely bears the load torque TL, the power consumption of the device is small.
If a lower frequency signal is applied to the input terminal
48
to rotate the rotor
20
during the generating sounds by the speaker diaphragm
14
, the magnetic flux density in the first gap
11
does not change from the magnetic flux density when only the speaker diaphragm
14
is vibrated. Therefore, quality of sounds generated by the diaphragm does not reduce even if the rotor
20
rotates.
Although the synchronous motor is used in the above described embodiments, other motors such as a stepping motor, a direct current motor and others can be used. Further, the rotor can be disposed outside the stator.
From the foregoing description, it will be understood that the present invention provides a multifunction acoustic device which may generate sounds and vibration of the frame at the same time without reducing sound quality. In the prior art, since the speaker diaphragm and the magnetic composition are vibrated in the same direction, the thickness of the device increases. In the device of the present invention, since the magnetic composition rotates, the thickness of the device can be reduced.
Furthermore, coils provided in the acoustic device are cooled by cooling devices, thereby improving the functions of the acoustic device.
While the invention has been described in conjunction with preferred specific embodiment thereof, it will be understood that this description is intended to illustrate and not limit the scope of the invention, which is defined by the following claims.
Claims
- 1. A multifunction acoustic device comprising:a frame; a rotor shaft rotatably supported in the frame by bearings; a rotor rotatably supported in the frame by the rotor shaft, and having a yoke with a central upward cylindrical portion and an annular flat portion extending from and around the central upward cylindrical portion; a stator provided in the frame within the central upward cylindrical portion of the yoke; an annular first permanent magnet provided on the annular flat portion of the yoke; an annular second permanent magnet provided on an annular, inside wall of the central upward cylindrical portion of the yoke; a diaphragm supported in the frame; a voice coil secured to the diaphragm and inserted in a gap defined by the first permanent magnet and an outer surface of the central upward cylindrical portion of the yoke; and at least two coils provided on the stator for forming magnetic fluxes between the annular second permanent magnet and the stator so as to rotate the rotor.
- 2. The device according to claim 1 further comprising eccentric means provided on the rotor for vibrating the rotor during the rotation of the rotor.
- 3. The device according to claim 1 wherein the stator comprises a spider having a hub and a plurality of spokes.
- 4. The device according to claim 1 wherein the coils are provided on spokes of the spider.
- 5. The device according to claim 2 wherein the eccentric means is a weight eccentrically provided in the rotor.
- 6. The device according to claim 3 further comprising an annular top yoke mounted on the first permanent magnet for forming the gap between the top yoke and the cylindrical portion of the yoke.
- 7. The device according to claim 5 further comprising a driving circuit for energizing the coils for rotating the rotor.
- 8. The device according to claim 7 wherein the rotor and the stator are formed into a synchronous motor.
- 9. The device according to claim 8 wherein the periphery of the second permanent magnet has a plurality of magnetic poles corresponding to the spokes of the stator.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2001-016435 |
Jan 2001 |
JP |
|
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Number |
Name |
Date |
Kind |
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Yamaguchi |
Aug 1999 |
A |
6274955 |
Satoh et al. |
Aug 2001 |
B1 |
6417589 |
Kuyama et al. |
Jul 2002 |
B1 |
6639992 |
Kobayashi et al. |
Oct 2003 |
B2 |