close

Вход

Забыли?

вход по аккаунту

?

JP2011244479

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2011244479
The present invention provides an electrostatic loudspeaker that simultaneously meets a certain
standard of acoustic transmittance and effective electrode area. An electrostatic loudspeaker (1)
according to the present invention, in a preferred embodiment, comprises a vibrating membrane
(10) displaceable by electrostatic force, and a conductive non-woven fabric provided opposite to
the vibrating membrane. Electrodes (20L, 20R), buffer members (30L, 30R) provided between
the vibrating membrane and the electrodes, and supporting portions (40L, 40R) for supporting
the flat electrode in the vibrating direction of the vibrating membrane Have. [Selected figure]
Figure 2
Electrostatic speaker
[0001]
The present invention relates to the structure of an electrostatic speaker.
[0002]
A speaker called an electrostatic speaker (capacitor speaker) is known.
Electrostatic loudspeakers are attracting attention because they are relatively simple in structure,
so they can be designed to be lightweight and compact, and that they can be theoretically
handled easily. Electrostatic loudspeakers are typically two parallel flat electrodes facing each
other across an air gap, and a conductive sheet-like member inserted between the electrodes and
04-05-2019
1
having its both ends supported by a housing etc. , A diaphragm or a diaphragm (so-called pushpull type). When a predetermined bias voltage is applied to the vibrating film and the voltage
applied to the electrodes is changed, the electrostatic force acting on the vibrating film changes,
and thereby the vibrating film is displaced. If this applied voltage is changed according to the
input musical tone signal, the vibrating membrane repeats displacement (i.e. vibrates)
accordingly, and an acoustic wave corresponding to the input musical tone signal is generated
from the vibrating membrane. The generated musical tone is emitted to the outside through, for
example, a hole formed in a metal plate electrode or other porous layer (see Patent Document 1).
[0003]
JP-A-2002-513263 (FIG. 1 etc.)
[0004]
However, when using, for example, a metal plate in which a large number of through holes are
formed (so-called punching metal) or a porous material as an electrode, it contributes to the
electric field generated between the electrode plates compared to the case where there are no
holes. (The effective electrode area) decreases, and as a result, the capacitance between the
electrodes decreases, and the force (driving force) acting on the vibrating film decreases even if
the applied voltage is the same (hereinafter referred to as effective) The size of the electrode area
is called the electrostatic capacitance performance of the electrostatic speaker).
If the distance between the electrode and the vibrating membrane is increased, the influence of
the holes is relatively reduced, but the size of the speaker must be increased, and if the distance
between the vibrating membrane and the electrode is increased, it acts on the vibrating
membrane As the amount of electrostatic charge decreases, there are disadvantages such as the
need to increase the applied voltage to maintain the sound pressure. Although the influence of
the holes can be reduced by reducing the size and number of the holes, in this case, the sound
transmission performance is deteriorated.
[0005]
As described above, in the conventional electrostatic speaker, it is difficult to achieve both of the
sound transmission performance and the capacitance performance. Then, an object of the
present invention is to provide an acoustic element and an electrostatic speaker that
04-05-2019
2
simultaneously satisfy a certain standard of acoustic transmittance and effective electrode area.
[0006]
In order to solve the above problems, according to a preferred embodiment of the present
invention, there is provided a vibrating membrane displaceable by electrostatic force, an
electrode provided opposite to the vibrating membrane and configured of a conductive
nonwoven fabric, and the vibrating membrane There is provided an electrostatic speaker having
a buffer member provided between the electrode and the electrode.
[0007]
The present invention provides, in another preferred embodiment, a diaphragm which is
displaceable by electrostatic force, an electrode which is provided opposite to the diaphragm and
which has a net-like structure, and which is provided between the diaphragm and the electrode.
And providing an electrostatic speaker.
[0008]
According to the electrostatic loudspeaker according to the present invention, certain criteria are
satisfied with respect to both the sound transmission performance and the capacitance
performance.
[0009]
FIG. 1 is an external perspective view of an electrostatic speaker 1;
FIG. 2 is a cross-sectional view of the electrostatic speaker 1;
It is experimental data about a capacitance characteristic.
It is experimental data about a sound transmission characteristic. FIG. 2 is a cross-sectional view
of an electrostatic speaker 2; It is a detail view of wire mesh electrode 40. FIG. It is experimental
data about a capacitance characteristic. FIG. 2 is a cross-sectional view of an electrostatic speaker
3; It is a figure for demonstrating an example of the structure of the supporting member 50. As
shown in FIG. FIG. 10 is a view for explaining another example of the structure of the support
04-05-2019
3
member 50.
[0010]
First Embodiment FIG. 1 is a perspective view of the general structure of an electrostatic speaker
1 according to an embodiment of the present invention. As shown in the figure, the electrostatic
speaker 1 includes a vibrating membrane 10, two parallel flat electrodes (hereinafter simply
referred to as electrodes) 20L and 20R facing the vibrating membrane 10, and the vibrating
membrane 10 and electrodes 20L and 20R. It is roughly constituted by cushion materials 30L
and 30R provided between them respectively. In the figure, the electrode surfaces of the
electrodes 20L and 20R are fixed in the X direction and the Y direction, and an example of the
arrangement in which the vibrating membrane 10 can vibrate in the Z direction perpendicular to
the electrode surfaces is shown. Hereinafter, since the structures of the electrodes 20L and 20R
are the same, ?L? and ?R? will be omitted unless there is a need to distinguish between the
two. The omission of ?L? and ?R? is the same for other components.
[0011]
Further, in the electrostatic speaker 1, a desired voltage is applied to each of the electrodes 20
from a power supply (not shown), and a bias voltage is applied on the diaphragm 10. Since a
conventional technique can be adopted as a method of supplying power to the electrode 20,
components related to power supply are not shown. The electrostatic speaker 1 further includes
an input unit for inputting an audio signal from the outside, and causes the diaphragm 10 to
vibrate according to the audio signal by changing the value of the applied voltage according to
the audio signal. It is possible to The sound wave generated by the vibration of the vibrating
membrane 10 passes through at least one of the electrodes 20 and is emitted to the outside of
the speaker. In order to prevent the drawings from being complicated, illustration of components
for generating and supplying audio signals is also omitted.
[0012]
The vibrating film 10 is, for example, a film made of PET (polyethylene terephthalate,
polyethylene terephthalate), PP (polypropylene, polypropylene) or the like by vapor-depositing a
metal film or applying a conductive paint, and has a thickness of several microns to several tens
of microns. It is a plate-like (film-like) member having a conductivity on the order of microns.
04-05-2019
4
Alternatively, it may be one obtained by laminating a metal thin film, or one obtained by applying
a high voltage to the insulating film and polarizing it. The vibrating membrane 10 is a fixing
means (not shown) formed of an insulating material such as vinyl chloride, acrylic (methyl
methacrylate), rubber, etc., in a state where a predetermined tension is acting on the vibrating
membrane 10, For example, one side of the edge may be supported by the housing (not shown)
of the electrostatic speaker 1, or may be supported by the action of the cushion members 30L
and 30R without providing such a support. It may be a configuration.
[0013]
The electrode 20 has a square shape on its electrode surface, and is fixed to a housing (not
shown) of the electrostatic speaker 1. At this time, the distance d (for example, about 0.1 to 10
mm) from the vibrating membrane 10 to both the electrodes 20L and 20R is arranged to be
equal. In other words, the exactly middle position of the opposing electrodes is the fixed position
of the vibrating membrane 10 (precisely, the vibrating membrane 10 in the non-displaced state,
which is a state when no signal is input). The shape of the electrode surface is not limited to a
square, and may be, for example, a rectangle or a circle.
[0014]
FIG. 2 is a cross-sectional view in the direction perpendicular to the electrode surface of the
electrostatic speaker 1, and the detailed structure of the electrode 20 will be described using this
figure. The electrode 20 is composed of a non-woven fabric layer 201 and a conductive layer
202. The conductive layer 202 is formed over the entire surface of the non-woven fabric layer
201, and is produced, for example, by sputtering the non-woven fabric layer 201 with a metal
such as aluminum. Alternatively, metal printing may be performed on the non-woven fabric layer
201. Alternatively, the non-woven fabric layer 201 may be coated with a conductive paint.
[0015]
Here, the non-woven fabric is a fiber having porous (porous) structural fibers, and has a sheetlike shape. For example, they are made by combining in a fixed direction or at random and
chemically bonding with an adhesive resin, mechanical entanglement, entanglement with a
pressure-applied water stream, or bonding with a fused fiber. In the present invention, the air
permeability (i.e., the sound transmission performance) is made of a punching metal (PM) so that
04-05-2019
5
the capacitance is substantially the same as in the case of using a flat plate electrode without
holes. The nonwoven fabric which has a high structure compared with the case where it
comprises using an electrode is used. For example, one having a basis weight of 40 g / m 2, a
thickness of 0.1 mm, and a fiber diameter of 2 denier is preferable. However, the nonwoven
fabric which concerns on a present Example is not limited to the thing which has a structure
specified by said value, The thing of the structure which has a value other than this can be used.
Hereafter, the structure of a suitable nonwoven fabric is further demonstrated from each
viewpoint of electrostatic capacity performance and sound transmission performance.
[0016]
The cushion material 30 is made of an insulating material, and is, for example, a sponge, sheetlike cotton, or an insulating non-woven fabric. By inserting the cushion material 30, it is possible
to support the vibrating membrane 10 with respect to the housing or to apply appropriate elastic
stress to the vibrating membrane 10. The mechanical properties and the like are not particularly
limited, but it has air permeability higher than that of the electrode 20, and preferably has an air
permeability of 95% or more, for example.
[0017]
(1) Capacitance performance FIG. 3 shows one of the electrodes when the capacitance measured
with a pair of parallel flat electrodes (without holes) made of metal is 1 (100%). The capacitance
value measured by replacing the non-woven fabric using the non-woven fabric of the structure of
the above exemplified value with the same area (hereinafter referred to as non-woven fabric
electrode), and the PM having several pore sizes and open areas The value of the capacitance
measured by replacement is shown together with the electrode distance. In the figure, A indicates
data in the case of replacing with a non-woven fabric electrode, E to I indicate pore diameter and
aperture ratio {2 mm, 20%}, {2 mm, 40%}, {3 mm, 40%}, {6 mm The data in the case of replacing
with PM of 40%, {8 mm, 40%} are shown. As can be seen from the figure, in the case of using PM,
the capacitance decreases significantly as the distance between the electrodes is reduced. This is
because, as described above, when the distance between the electrodes decreases, the influence
of the holes increases. On the other hand, in the case of using the non-woven fabric electrode
according to the present example, no drop in capacitance is observed even if the distance
between the electrodes is reduced, and a substantially constant value (about 100%) is taken. It
can be said that the capacitance performance is substantially equivalent to that of the planar
electrode.
04-05-2019
6
[0018]
(2) Sound transmission performance FIG. 4 shows a general speaker, and a measuring instrument
for analyzing the frequency characteristics of the sound emitted from the speaker at a
predetermined distance from the general speaker, and the speaker and the measuring instrument
The difference between the frequency characteristics deviations (the degree of distortion of the
acoustic wave) obtained with the measuring instrument in the case where measurement was
carried out by placing PM between them and the measurement by placing the non-woven fabric
electrode according to this example It is In the figure, PM (1) to (3) are data in the case of putting
PM with a hole diameter of 8 mm, 2 mm and 2.5 mm, respectively, and NW is data in the case of
putting a non-woven fabric electrode. If there is no shield between the speaker and the
measuring instrument, the frequency characteristics of the sound emitted by the speaker and the
measuring instrument substantially match, so the obtained data is zero regardless of the
frequency. That is, it can be said that the smaller the deviation from zero, the better the sound
transmission performance. When PM is used as a shield, it can be seen that the acoustic wave is
distorted by the frequency band until it reaches the measuring device due to the influence of the
sound wave passing through the PM. On the other hand, when a non-woven fabric electrode is
used as the shield, some distortion is measured, but the sound pressure level is generally about
1/3 to 1/4 as compared with the case of PM. As described above, it can be said that the electrode
20 made of the non-woven fabric according to the present embodiment is superior to the general
PM in the sound transmission performance.
[0019]
Example 2 FIG. 5 is a cross-sectional view of an electrostatic loudspeaker 2 according to another
example of the present invention. The electrostatic loudspeaker 2 is different from the
electrostatic loudspeaker 1 in that electrodes 40R and 40L are used instead of the electrodes
20R and 20L. FIG. 6 shows the details of the structure of the electrode 40. As shown in FIG. As
shown in the figure, the electrode 40 is a grid formed of a conductive material such as metal. For
example, a woven wire mesh of JIS G3555, 3556, etc., which is a mesh # 20 to # 500 can be
used. Here, the mesh means the number of eyes between 25.4 mm on one side. FIG. 7 shows a
wire mesh of the above exemplified structure having the same area as one of the electrodes when
the capacitance measured with a pair of parallel flat metal electrodes (without holes) is 1 (100%).
The value of capacitance measured by replacing it with an electrode using a non-woven fabric
(referred to as a metal mesh electrode) (referred to as effective capacitance) and capacitance
measured by replacing it with PM having several pore sizes and aperture ratios The value of V is
shown together with the electrode spacing. In the figure, B to D respectively indicate data in the
04-05-2019
7
case of being replaced with metal mesh electrodes, and E to I are the same as the data of PM
shown in FIG. As can be seen from the figure, when the metal electrode according to the present
embodiment is used, the drop in capacitance is small compared to the case where PM is used
even if the distance between the electrodes is reduced. For example, even if the electrode spacing
is 1 mm, an effective capacitance of 95% or more can be obtained. For example, in the case of
using a plain woven wire mesh with a mesh # 40 and a wire diameter of 0.16 mm, the porosity
(corresponding to the hole area ratio in PM) that affects the sound transmission performance is
about 40%. That is, when the electrode 40 according to the present embodiment is used, while
achieving acoustic transmission performance equivalent to PM, electrostatic capacitance
performance can be obtained even though it is higher than PM having a similar aperture ratio. As
a wire mesh used for the electrode 40, for example, if it is a space ratio (for example, 20 to 50%)
that does not substantially deteriorate the sound transmission performance when used as an
audio speaker, the weave, the wire diameter, the meshing And any material can be used.
[0020]
<Other Embodiments> FIG. 8 shows a cross-sectional view of the electrostatic loudspeaker 3
according to the present invention. As shown in the figure, the electrostatic speaker 3 is
configured by providing supporting members 50L and 50R on the outside of the electrodes 20L
and 20R of the electrostatic speaker 1, respectively. The support member 50 is made of, for
example, a metal material, and preferably uses a so-called flexible tube which holds a bent shape
and is excellent in bending durability, formed by winding a wire having a triangular shape
around a spiral spring. Be Further, the support member 50 may be fixed to the housing or to the
electrode 20. However, in the case of fixing to the electrode 20, the fixing portion is subjected to
a predetermined insulation treatment. FIG. 9 is a view for explaining the structure of the support
member 50. As shown in FIG. As shown in the figure, the support member 50 has a lattice shape
so as not to substantially impair the sound transmission performance. This shape can be
obtained, for example, by knitting the flexible tube. When the non-woven fabric constituting the
electrode 20 has a certain degree of flexibility (for example, in the form of a sheet), depending on
conditions such as the applied voltage and the installation condition of the electrode 20, the
electrode 20 may May bend. Even if a force is applied to the inside of the electrode 20, deflection
can be suppressed to a certain extent because of the presence of the cushion member 30, but if a
force is applied to the outside, the electrode 20 is flexed. However, according to the present
embodiment, by using the support member 50 on the outer side of the electrode 20, the
deflection can be prevented.
[0021]
04-05-2019
8
Furthermore, as shown in FIG. 10, it is also possible to fix the support member 50 in a state of
being bent in the z direction in advance. In the example shown in FIG. 10, the center of the
support member is most bent and the bending becomes gentler toward the periphery. In this
case, the bending degree of the electrode 20 can be forced to a predetermined shape (for
example, a parabolic shape as shown in FIG. 10). By adjusting the degree of deflection, it is
possible to control the directivity of the acoustic wave emitted from the electrode 20.
[0022]
Although the cushioning material 30 is provided between the electrode 20 and the vibrating
membrane 10 in the above embodiment, the cushioning material 30 may be omitted. In this case,
in order to prevent contact between the vibrating membrane 10 and the electrode, for example, it
is preferable to provide spacers at the four corners of the vibrating membrane.
[0023]
Alternatively, the cushioning material 30 may be formed of the insulating non-woven fabric
having the above-described structure used for the electrode 20, and a conductive layer may be
provided on the outer surface (that is, the electrode side) of the cushioning material 30. In this
case, the cushioning material 30 can also function as the electrode 20 without providing the
electrode 20.
[0024]
Moreover, although the example of the electrode 20 in which the conductive layer was formed in
the surface of the nonwoven fabric was shown in Example 1, the thickness of this layer is
arbitrary. The point is that the non-woven fabric constituting the electrode according to the
present invention only needs to have the above-mentioned structure that exhibits the abovementioned sound transmission performance and capacitance performance, and does not
necessarily have to have a layer structure. For example, each fiber may be made conductive, and
it may be made conductive anywhere in the interior of the non-woven fabric.
[0025]
04-05-2019
9
The location where the support member 50 is provided is not limited to the outside of the
electrode 20 or 40, but may be provided inside (that is, between the vibrating membrane 10 (or
the cushioning material 30) and the electrode 20 or 40), or both inside and outside It may be
[0026]
In the embodiment described above, only specific combinations of the diaphragm 10, the
electrodes 20 or 40, the cushion member 30, and the support member 50 are illustrated as
components of the electrostatic speaker, but this is for convenience of description. It is possible,
for example, to adopt any combination other than those described above for the presence or
absence of the cushion material 30 and the presence or absence of the support member 50.
[0027]
Further, although the example of the push-pull type electrostatic speaker using the pair of
electrodes 20 or 40 facing each other has been shown in the embodiment described above, the
present invention is not limited thereto, and only one electrode according to the present
invention is used. It is also possible to configure a push-type electrostatic speaker.
[0028]
1, 2, 3 иииии Electrostatic speaker, 10 иии diaphragm, 20, 20 L, 20 R, 40 L, 40 R иии electrode иии nonwoven fabric electrode, 30 L, 30 R иии cushion material 50R: supporting member, 201L, 201R:
non-woven fabric layer, 202L, 202R: conductive layer
04-05-2019
10
Документ
Категория
Без категории
Просмотров
0
Размер файла
22 Кб
Теги
jp2011244479
1/--страниц
Пожаловаться на содержимое документа