Information
-
Patent Grant
-
6621911
-
Patent Number
6,621,911
-
Date Filed
Tuesday, December 4, 200122 years ago
-
Date Issued
Tuesday, September 16, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Dennison, Schultz & Dougherty
-
CPC
-
US Classifications
Field of Search
US
- 340 4071
- 340 6931
- 340 6935
- 381 396
- 381 412
- 381 421
- 381 401
-
International Classifications
-
Abstract
A speaker diaphragm having a voice coil secured thereto is provided in a frame, a rotor having a permanent magnet is rotatably supported in the frame, and a stator having poles is provided in the frame. The permanent magnet provided on the rotor is provided for forming a magnetic circuit passing through the rotor and the stator, and a stator coil is provided in the stator. A driving circuit is provided for energizing the stator coil for rotating 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 diaphragm and a permanent magnet magnetically connected to a voice coil mounted on the diaphragm 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. 6
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
509
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
509
.
By applying a low or high frequency signal to the voice coil
509
, 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
509
and the magnet
510
. Consequently, when a low frequency signal or a high frequency signal is applied to the voice coil
509
, 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
509
and the magnet
510
causes the low frequency vibration of the magnet to superimpose on the magnetic combination of the voice coil
509
and the magnet
510
, which further largely distorts the sounds.
FIG. 7
is a sectional view showing a conventional multifunction acoustic device. The device comprises a speaker diaphragm
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 diaphragm
603
at a central portion, and a magnet composition
610
. The diaphragm
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 diaphragm
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 diaphragm
603
and the magnetic composition
610
are sequentially vibrated, since the magnetic composition
610
and the speaker diaphragm
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. 8
is a sectional view showing another conventional multifunction acoustic device. The device comprises the speaker diaphragm
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 diaphragm
603
at a central portion, and the magnet composition
610
. The diaphragm
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
606
a
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 diaphragm
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 diaphragm
603
and the magnetic composition
610
are sequentially vibrated, since the magnetic composition
610
and the speaker diaphragm
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 diaphragm
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 diaphragm
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 diaphragm
603
and magnetic composition
610
are sequentially vibrated, thereby reducing the sound quality.
In the above described conventional devices, both the speaker diaphragm 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.
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.
According to the present invention, there is provided a multifunction acoustic device comprising a frame, a speaker diaphragm supported in the frame, a voice coil secured to the speaker diaphragm, a rotor having an annular rotor permanent magnet and rotatably supported in the frame, a stator having magnetic poles and provided in the frame, corresponding to the rotor, a stator coil for forming magnetic fluxes between the rotor permanent magnet of the rotor and the magnetic poles of the stator.
The device further comprises a cylindrical speaker yoke secured to a bottom of the frame at a central portion thereof, a speaker permanent magnet secured to a bottom of the speaker yoke, and a top plate secured to the top of the speaker permanent magnet, eccentric means provided on the rotor for vibrating the rotor during the rotation of the rotor.
The voice coil is disposed in a gap formed between the speaker yoke and the top plate.
The rotor permanent magnet is rotatably supported on the outside peripheral wall of the speaker yoke.
The eccentric means is a weight eccentrically provided on the rotor.
A driving circuit is provided for energizing the coil in the stator 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 an exploded perspective view of a stator of the multifunction acoustic device of the present invention;
FIG. 5
is a driving circuit used in the multifunction acoustic device of the present invention;
FIG. 6
is a sectional view of a conventional electromagnetic induction converter;
FIG. 7
is a sectional view showing a conventional multifunction acoustic device; and
FIG. 8
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 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.
A cylindrical speaker yoke
21
made of a magnetic material is secured to a base plate of the frame
1
at a central portion thereof, and a cylindrical speaker permanent magnet
22
is secured on the bottom of the speaker yoke
21
which is magnetized in the axial direction. A top yoke
23
made of a magnetic material is secured to the top of the permanent magnet
22
. The voice coil
15
is disposed in a speaker gap
11
formed between the outside wall of the top yoke
23
and the inside wall of the speaker yoke
21
.
The rotor
20
comprises an annular rotor permanent magnet
24
rotatably mounted on the base plate of the frame
1
, and on the outside wall of the speaker yoke
21
through an annular thrust ball bearing
25
and a cylindrical ball bearing
26
. The annular permanent magnet
24
is magnetized in radial directions.
A semicircular weight
27
(
FIG. 2
) is securely mounted on the permanent magnet
24
. As another means, the permanent magnet
24
may be eccentrically disposed with respect to the axis of the rotor
20
. As shown in
FIGS. 1 and 2
, the annular stator
30
is disposed around the rotor
20
, so that a second gap
12
is formed between the periphery of the rotor
20
and the inside wall of the annular stator
30
.
Referring to
FIG. 4
, the stator
30
comprises an annular stator coil
33
, annular upper and lower shading plates
36
and
35
disposed on the upper and lower sides of the annular coil
33
, and annular upper and lower stator yokes
31
and
32
. The upper stator yoke
31
has four main magnetic poles
31
a
1
,
31
b
1
,
31
c
1
and
31
d
1
, and four auxiliary magnetic poles
31
a
2
,
31
b
2
,
31
c
2
and
31
d
2
. Each of the magnetic poles extends in the axial direction and toward the lower stator yoke
32
. The lower stator yoke
32
has four main magnetic poles
32
a
1
,
32
b
1
,
32
c
1
and
32
d
1
and four auxiliary magnetic poles
32
a
2
,
32
b
2
,
32
c
2
and
32
d
2
.
A couple of upper main and auxiliary magnetic poles
31
a
1
and
31
a
2
and a couple of lower main and auxiliary magnetic poles
32
a
1
and
32
a
2
, and other couples of the magnetic poles are angularly disposed atone magnetic pole pitch of 90 degrees (electric angle 360°). The sum of widths of the main magnetic pole and the auxiliary magnetic pole is within 45 degrees, and the width of the main magnetic pole is larger than that of the auxiliary magnetic pole.
The couple of upper main and auxiliary magnetic poles and the couple of lower main and auxiliary magnetic poles are alternately disposed on the same circle as shown in FIG.
2
.
The upper shading plate
36
has four holes
36
a,
36
b,
36
c
and
36
d,
each formed in a projection projected from the inside wall of the shading plate
36
in the radially inward direction. Similarly, the lower shading plate
35
has four holes
35
a,
35
b,
35
c
and
35
d.
The auxiliary magnetic poles
31
a
2
,
31
b
2
,
31
c
2
and
31
d
2
of the upper stator yoke
31
are inserted in the holes
36
a
-
36
d
of the upper shading plate
36
. Similarly, the auxiliary magnetic poles
32
a
2
,
32
b
2
,
32
c
2
and
32
d
2
of the lower stator yoke
32
are inserted in the holes
35
a
-
35
d
of the lower shading plate
35
.
Referring to
FIGS. 1 and 4
, the lower stator yoke
32
has a cylindrical peripheral wall
32
e.
The lower shading plate
35
is mounted on the lower stator yoke
32
between the peripheral wall
32
e
and main and auxiliary magnetic poles. The stator coil
33
, upper shading plate
36
, and upper stator plate
31
are stacked on the lower shading plate
35
in order. 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 having a permanent magnet rotor having multiple polarities.
The magnetomotive force of the permanent magnet
24
is applied to the second gap
12
, so that a necessary magnetic flux density for the rotor
20
is provided.
Referring to
FIG. 5
, 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 coil
33
through the transistors
41
and
44
from the Vcc to GND. And the current passes through the transistor
43
, coil
33
and transistor
42
at a low level of the input signal. Thus, an alternating current of the low frequency corresponding to the input low frequency signal flows in the stator coil
33
. Consequently, couples of main pole
32
a
1
and auxiliary pole
32
a
2
to poles
32
d
1
and
32
d
2
are energized. At that time, magnetic flux generated by four auxiliary poles
31
a
2
,
31
b
2
,
31
c
2
and
31
d
2
, and magnetic flux generated by four auxiliary poles
32
a
2
,
32
b
2
,
32
c
2
and
32
d
2
are delayed in phase by eddy currents passing through holes
36
a
-
36
d
of the upper shading plate
36
and holes
35
a
-
35
d
of the lower shading plate
35
to produce a shifting magnetic field to generate rotating power in a predetermined direction. Thus, the rotor
20
is rotated at the driving low frequency. Since the weight
27
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.
The number N of rotation of the rotor is expressed as follows.
N=
60
f/Z
(rpm) 1
where
Z is a pair of 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
27
of the rotor,
R is the length between the center of the rotor and the center of gravity of the weight
27
,
r is the radius of the rotor,
μ is the friction coefficient between the rotor and the speaker yoke
21
,
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.
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.
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 cylindrical speaker yoke secured to a bottom of the frame at a central portion thereof; a speaker permanent magnet secured to a bottom of the speaker yoke; a top plate secured to the top of the speaker permanent magnet; a speaker diaphragm supported in the frame; a voice coil secured to the speaker diaphragm, and disposed in a gap formed between the top plate and the cylindrical speaker yoke; a rotor having an annular rotor permanent magnet and rotatably supported in the frame; a stator having magnetic poles and provided in the frame, corresponding to the rotor; and a stator coil for forming magnetic fluxes between the rotor permanent magnet of the rotor and the magnetic poles of the stator.
- 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 rotor permanent magnet is rotatably supported on the outside peripheral wall of the speaker yoke.
- 4. The device according to claim 2, wherein the eccentric means is a weight eccentrically provided on the rotor.
- 5. The device according to claim 3, further comprising a driving circuit for energizing the coil in the stator for rotating the rotor.
- 6. The device according to claim 5, wherein the rotor and the stator are formed into a synchronous motor.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-384600 |
Dec 2000 |
JP |
|
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4931765 |
Rollins et al. |
Jun 1990 |
A |