Information
-
Patent Grant
-
6718040
-
Patent Number
6,718,040
-
Date Filed
Thursday, June 15, 200024 years ago
-
Date Issued
Tuesday, April 6, 200420 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 381 407
- 381 408
- 381 409
- 381 410
- 381 191
- 381 150
- 381 174
- 381 192
- 381 116
- 381 117
- 381 111
- 381 400
- 381 59
- 381 402
- 381 181
- 336 198
- 336 208
- 336 192
- 336 222
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International Classifications
-
Abstract
A transformer includes a bobbin having a cavity, a primary winding wound around the bobbin, and a secondary winding wound around the bobbin and magnetically coupled with the primary winding. In the transformer, at least one of the primary winding and the secondary winding is divided into at least two portions which include a portion wound at an inside region of the transformer and a portion wound at an outside region of the transformer. Also, at least a portion of the other one of the primary winding and the secondary winding is wound between said at least two portions obtained by dividing the one of the primary winding and the secondary winding, and at least a portion of the cavity of the bobbin is used as a space to dispose another member therein.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to transformers, loudspeaker devices, loudspeaker networks, and loudspeaker systems, and more specifically relates to a transformer included in a piezoelectric loudspeaker, and to a loudspeaker device, a loudspeaker network, and a loudspeaker system that include the above-described transformer.
2. Description of the Related Art
A transformer for a conventional piezoelectric loudspeaker is constructed such that a primary winding and a secondary winding are wound around a bobbin and a core is inserted into the bobbin.
In the above-described transformer for the conventional piezoelectric loudspeaker, the transformer is expensive as well as heavy due to the use of the core. Accordingly, the removal of the core has been contemplated to produce an inexpensive and light-weight transformer. However, the removal of the core decreases the magnetic coupling strength between the primary winding and the secondary winding. Moreover, to reduce the size of the piezoelectric loudspeaker, it is desirable to provide another member, such as a portion of the loudspeaker, within the above-described transformer of the conventional piezoelectric loudspeaker. These points also apply to a loudspeaker device, a loudspeaker network, and a loudspeaker system that include the transformer for the conventional piezoelectric loudspeaker.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide an inexpensive, compact, and lightweight transformer which has strong magnetic coupling between a primary winding and a secondary winding, and which can hold another member therein.
Further, preferred embodiments of the present invention provide a loudspeaker device, a loudspeaker network, and a loudspeaker system which include a transformer that is inexpensive, compact, and lightweight, and that has strong magnetic coupling between a primary winding and a secondary winding, and which has another member disposed therein.
According to a first preferred embodiment of the present invention, a transformer including a bobbin having a cavity, a primary winding wound around the bobbin, and a secondary winding wound around the bobbin and magnetically coupled with the primary winding is provided. In the transformer, at least one of the primary winding and the secondary winding is divided into at least two portions which include a portion wound at the inside and a portion wound at the outside, at least a portion of the other one of the primary winding and the secondary winding is wound between said at least two portions obtained by dividing the one of the primary winding and the secondary winding, and at least a portion of the cavity of the bobbin is used as a space to accommodate another member therein.
According to another preferred embodiment of the present invention, a loudspeaker device includes a transformer as described in the previous paragraph, and a loudspeaker, connected to the transformer, and including a sound-producing body having a piezoelectric body. In the loudspeaker device, at least a portion of the loudspeaker is provided in the cavity of the bobbin.
In the loudspeaker device according to another preferred embodiment of the present invention, the loudspeaker has a horn for conducting sound waves transmitted from the sound-producing body, one end of the horn is inserted into the cavity of the bobbin, and the bobbin of the transformer is mounted on the horn.
According to another preferred embodiment of the present invention, a loudspeaker network includes a transformer having the features of the preferred embodiment described above and an impedance network connected to the transformer.
According to a further preferred embodiment of the present invention, a loudspeaker system includes a loudspeaker device according to a preferred embodiment described above, and a loudspeaker network according to the preferred embodiment described above. In the loudspeaker device, the transformer of the loudspeaker device includes the transformer of the loudspeaker network.
Since there is no core used in the transformer, the transformer is inexpensive as well as lightweight.
Furthermore, in the transformer according to preferred embodiments of the present invention, since at least one of the primary winding and the secondary winding is wound between at least two portions obtained by dividing the other one of the primary winding and the secondary winding, the magnetic coupling between the primary winding and the secondary winding of the transformer is stronger than a transformer constructed by winding the entire primary winding and the winding the entire secondary.
Also, in the transformer according to preferred embodiments of the present invention, since a portion of the cavity of the bobbin is used as a space for having another member disposed therein, another member, such as an end portion of the horn of the loudspeaker, can be disposed therein.
Other features, characteristics, arrangements and advantages of the present invention will become more apparent from the detailed description of preferred embodiments of the present invention with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is an illustration showing one example of a loudspeaker system according to a preferred embodiment of the present invention;
FIG. 2
is an illustration showing a loudspeaker device of the loudspeaker system shown in
FIG. 1
;
FIG. 3
is a sectional view showing a vibrator of a piezoelectric loudspeaker included in the loudspeaker system shown in
FIG. 1
;
FIG. 4
is a circuit diagram of the loudspeaker system shown in
FIG. 1
;
FIG. 5
is a graph showing frequency characteristics of the boost ratio of a loudspeaker network used in the loudspeaker system shown in
FIG. 1
;
FIG. 6
is a graph showing frequency characteristics of the impedance of the loudspeaker network used in the loudspeaker system shown in
FIG. 1
;
FIG. 7
is a graph showing frequency characteristics of the sound pressure of the loudspeaker system shown in
FIG. 1
; and
FIG. 8
is a perspective view of another preferred embodiment of a loudspeaker system according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1
is an illustration showing one example of a loudspeaker system according to a preferred embodiment of the present invention.
FIG. 2
is an illustration showing a loudspeaker device of the loudspeaker system. A loudspeaker system
10
shown in
FIG. 1
preferably includes a substantially cylindrical casing
12
made of synthetic resin, or other suitable material. One end of the casing
12
is open while the other end has a disk-shaped lid
14
adhered thereto.
The casing
12
has a piezoelectric loudspeaker
20
mounted therein as a tweeter. The piezoelectric loudspeaker
20
includes a disk-shaped supporting member
22
as shown in
FIG. 2. A
hole
22
a
, serving as a so-called “air vent” is provided at the approximate center of the supporting member
22
. One major surface of the supporting member
22
has a substantially hemispherical vibrator
24
with a diameter of about 20 mm attached thereto. The vibrator
24
functions as a sound-producing body and includes a substantially hemispherical vibrating body
26
which is made of a piezoelectric material, such as a piezoelectric ceramic, or other suitable piezoelectric material, polarized in the thickness direction, as shown in FIG.
3
. Electrodes
28
a
and
28
b
are provided on the internal surface and external surface of the vibrator
24
, respectively.
As shown in
FIG. 2
, input terminals
30
a
and
30
b
each have one end thereof soldered to the electrodes
28
a
and
28
b
of the vibrator
24
, respectively. Furthermore, a horn
32
made of a synthetic resin, or other suitable material, is mounted around the supporting member
22
.
The horn
32
is configured so that the width thereof gradually increases from one end
34
towards the other end
36
. The end
34
of the horn
32
includes a step and the other end
36
of the horn
32
includes a flange. The end
34
of the horn
32
is adhered to the surrounding of the supporting member
22
, thus securing the input terminals
30
a
and
30
b
between the end
34
of the horn
32
and the surrounding of the support member
22
, as shown in FIG.
2
. The other end
36
of the horn
32
is adhered to one end of the casing
12
as shown in
FIG. 1
, and supports the piezoelectric loudspeaker
20
in the casing
12
. In this piezoelectric loudspeaker
20
, by inputting a signal across the input terminals
30
a
and
30
b
, the vibrator
24
vibrates, and a sound is produced from the horn
32
.
Furthermore, the loudspeaker system
10
includes a loudspeaker network
40
. The loudspeaker network
40
includes a transformer
50
and an impedance network
70
.
As shown in
FIG. 2
, the transformer
50
includes a substantially cylindrical bobbin
52
made of a synthetic resin, or other suitable material. The bobbin
52
has a cavity
52
a
in the approximate center thereof. The nose of the end
34
of the horn
32
of the piezoelectric loudspeaker
20
is inserted into the cavity
52
a
of the bobbin
52
. Thus, the bobbin
52
is fixedly adhered around the end
34
of the horn
32
. In this case, not only the end
34
of the horn
32
but also the supporting member
22
of the piezoelectric loudspeaker
20
and middle portions of the input terminals
30
a
and
30
b
are provided in the cavity
52
a
of the bobbin
52
. A primary winding
54
and a secondary winding
56
are wound around this bobbin
52
. In this case, the secondary winding
56
is divided into two portions
56
a
and
56
b
. The portion
56
a
of the secondary winding
56
, the primary winding
54
, and the portion
56
b
of the secondary winding
56
are wound in that order around the bobbin
52
, such that the primary winding
54
is sandwiched between portions
56
a
and
56
b
of the secondary winding
56
. Furthermore, in the secondary winding
56
, one end of the portion
56
a
is connected to the input terminal
30
a
of the piezoelectric loudspeaker
20
, the other end of the portion
56
a
is connected to one end of the portion
56
b
, and the other end of the portion
56
b
is connected to the input terminal
30
b
of the piezoelectric loudspeaker
20
. That is, the ends of the secondary winding
56
are connected to the corresponding input terminals
30
a
and
30
b
of the piezoelectric loudspeaker
20
. The ends of the primary winding
54
are connected to corresponding terminals
58
a
and
58
b
. These terminals
58
a
and
58
b
are mounted via an insulating tape
60
on the portion
56
b
of the secondary winding
56
.
As described above, the loudspeaker device is constructed by combining the piezoelectric loudspeaker
20
and the transformer
50
.
As shown in
FIG. 1
, the impedance network
70
includes a capacitor
72
of about 2 μF and a resistor
74
of about 6.7 kΩ, or other suitable capacitance and resistance. One end of the capacitor
72
and one end of the resistor
74
are connected to the two terminals
58
a
and
58
b
of the transformer
50
, respectively. The other end of the capacitor
72
and the other end of the resistor
74
are connected to two external terminals
76
a
and
76
b
, respectively. These external terminals
76
a
and
76
b
are mounted so as to penetrate the lid
14
of the casing
12
.
Therefore, this loudspeaker system
10
includes a circuit shown in FIG.
4
.
Since there is no core provided in the transformer
50
of the loudspeaker network
40
, the loudspeaker system
10
is inexpensive as well as lightweight.
Since the primary winding
54
is wound between the two portions
56
a
and
56
b
obtained by dividing the secondary winding
56
of the transformer
50
of this loudspeaker system
10
, the magnetic coupling between the primary winding
54
and the secondary winding
56
is stronger than the magnetic coupling between a primary winding and a secondary winding of a transformer constructed by winding the primary winding and the secondary winding in that order, such that the primary winding is not sandwiched between two portions of the secondary winding.
Furthermore, in this loudspeaker system
10
, the cavity
52
a
of the bobbin
52
of the transformer
50
is effectively used as a space for disposing the supporting member
22
and the input terminals
30
a
and
30
b
of the piezoelectric loudspeaker
20
, and the end
34
of the horn
32
.
In this loudspeaker system
10
, as shown by frequency characteristics of the boost ratio of the loudspeaker network
40
in
FIG. 5
, the boost ratio is high in the high frequency band. Accordingly, this loudspeaker system
10
produces an outstanding tweeter because high sound pressure is obtained from the piezoelectric loudspeaker
20
in the high frequency band.
In this loudspeaker system
10
, the frequency characteristics of the impedance of the loudspeaker network
40
as shown in
FIG. 6
illustrate that the impedance is high at portions of the low frequency band. Accordingly, when this loudspeaker system
10
is connected in parallel with another loudspeaker, such as a woofer, this loudspeaker system
10
performs very well because it does not practically affect a signal in the low frequency band. Frequency characteristics of sound pressures concerning this loudspeaker system
10
, another loudspeaker system, and the loudspeaker system obtained by connecting these systems in parallel are shown in FIG.
7
. According to the frequency characteristics shown in
FIG. 7
, the other loudspeaker system does not have a very high sound pressure in the high frequency band. However, by connecting the loudspeaker system
10
in parallel with the other loudspeaker system, the sound pressure is increased in the high frequency band while it is not substantially affected in the low frequency band.
In this loudspeaker system
10
, the end
34
of the horn
32
of the piezoelectric loudspeaker
20
is a node of the piezoelectric loudspeaker
20
. Since the loudspeaker device is constructed by mounting the transformer
50
at the end
34
, a loudspeaker device having a compact structure is produced, in which the transformer
50
does not substantially affect the vibration of the piezoelectric loudspeaker
20
and the space of the air-core unit of the transformer
50
(the cavity
52
a
) can be effectively utilized.
In this loudspeaker system
10
, since a core is not used in the transformer
50
, the inductance of the transformer
50
is greatly reduced, and the desired inductance is obtained in the high frequency band. Accordingly, the transformer
50
is well-suited for use in the loudspeaker network
40
.
FIG. 8
is a perspective view showing another preferred embodiment of the loudspeaker system according to the present invention. A loudspeaker system
10
shown in
FIG. 8
has the piezoelectric loudspeaker
20
and the loudspeaker network
40
, along with a midrange
90
and a woofer
100
, mounted in one casing
80
.
In the above described loudspeaker system
10
, unlike in the transformer
50
of the loudspeaker network
40
where the primary winding
54
is wound between the two portions
56
a
and
56
b
of the secondary winding
56
, the secondary winding
56
can be wound between two portions of the primary winding
54
. Alternatively, portions obtained by dividing each of the primary winding
54
and the secondary winding
56
into at least two portions may be alternately wound from among the primary winding portions and the secondary winding portions.
Although in the above-described loudspeaker system
10
, the supporting member
22
and the input terminals
30
a
and
30
b
of the piezoelectric loudspeaker
20
and the one end of the horn
32
are provided within the cavity
52
a
of the bobbin
52
of the transformer
50
, other members may also be disposed therein.
In the above-described loudspeaker system
10
, although the impedance network
70
including the capacitor
72
and the resistor
74
is provided, another impedance network may be used.
In the above-described loudspeaker system
10
, although the piezoelectric loudspeaker
20
is used, another type of loudspeaker may be used.
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skill in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit of the invention.
Claims
- 1. A loudspeaker device comprising:a transformer comprising: a bobbin having a cavity; a primary winding wound around said bobbin; and a secondary winding wound around said bobbin and magnetically coupled with said primary winding; wherein at least one of said primary winding and said secondary winding is divided into at least two portions which include a portion wound at an inside region of the transformer and a portion wound at an outside region of the transformer; at least a portion of the other one of said primary winding and said secondary winding is wound between said at least two portions obtained by dividing the one of said primary winding and said secondary winding; and at least a portion of said cavity of said bobbin is used as a space to dispose another member therein; and a loudspeaker, connected to said transformer, and including a sound-producing body having a piezoelectric body; wherein at least a portion of said loudspeaker is provided in said cavity of said bobbin.
- 2. A loudspeaker device according to claim 1 wherein said loudspeaker includes a horn to conduct sound waves transmitted from said sound-producing body;one end portion of said horn is inserted into said cavity of said bobbin; and said bobbin of said transformer being mounted on said horn.
- 3. A loudspeaker network comprising:a transformer according to claim 1; and an impedance network connected to said transformer.
- 4. A loudspeaker system comprising:a loudspeaker device including a transformer having a bobbin having a cavity, a primary winding wound around said bobbin, and a secondary winding wound around said bobbin and magnetically coupled with said primary winding, wherein at least one of said primary winding and said secondary winding is divided into at least two portions which include a portion wound at an inside region of the transformer and a portion wound at an outside region of the transformer, at least a portion of the other one of said primary winding and said secondary winding is wound between said at least two portions obtained by dividing the one of said primary winding and said secondary winding, and at least a portion of said cavity of said bobbin is used as a space to dispose another member therein, said loudspeaker device being connected to said transformer, and including a sound-producing body having a piezoelectric body, at least a portion of said loudspeaker is provided in said cavity of said bobbin; and an impedance network connected to said transformer.
- 5. A loudspeaker system according to claim 4, wherein said loudspeaker includes a horn to conduct sound waves transmitted from said sound-producing body, one end portion of said horn is inserted into said cavity of said bobbin, and said bobbin of said transformer being mounted on said horn.
- 6. A loudspeaker device comprising:a transformer comprising: a bobbin having a cavity; a primary winding wound around said bobbin; and a secondary winding wound around said bobbin and magnetically coupled with said primary winding; wherein at least one of said primary winding and said secondary winding is divided into at least two portions which include a portion wound at an inside region of the transformer and a portion wound at an outside region of the transformer; at least a portion of the other one of said primary winding and said secondary winding is wound between said at least two portions obtained by dividing the one of said primary winding and said secondary winding; and wherein at least a portion of said cavity of said bobbin is used as a space to dispose another member therein; and a loudspeaker, connected to said transformer, and including a sound-producing body having a piezoelectric body.
- 7. A loudspeaker device according to claim 6, wherein at least a portion of said loudspeaker is provided in said cavity of said bobbin.
- 8. A loudspeaker device according to claim 6, wherein said loudspeaker includes a supporting member, and said sound-producing body is mounted on said supporting member.
- 9. A loudspeaker device according to claim 8, wherein said supporting member is disk-shaped and includes a hole in a approximate central portion thereof.
- 10. A loudspeaker device according to claim 6, wherein said loudspeaker includes a horn to conduct sound waves transmitted from said sound-producing body, one end portion of said horn is inserted into said cavity of said bobbin, and said bobbin of said transformer is mounted on said horn.
- 11. A loudspeaker device according to claim 6, wherein said loudspeaker includes a horn to conduct sound waves transmitted from said sound-producing body, and a supporting member, said horn being mounted on said supporting member, one end portion of said horn is inserted into said cavity of said bobbin, and said bobbin of said transformer is mounted on said horn.
- 12. A loudspeaker device according to claim 11, wherein said loudspeaker further includes a plurality of input terminals connected to said sound-producing body, and each of said plurality of input terminals having a portion disposed between said horn and said supporting member.
Priority Claims (2)
Number |
Date |
Country |
Kind |
11-172185 |
Jun 1999 |
JP |
|
2000-064948 |
Mar 2000 |
JP |
|
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Jul 1984 |
A |
4845776 |
Bittencourt |
Jul 1989 |
A |
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EP |
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JP |