JP2009038637

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 JP2009038637
An object of the present invention is to prevent a problem in a reproduction wave while vibrating
a vibrating body with high sensitivity. In the electrostatic speaker 1, a spacer 30L is fixed to the
peripheral portion of an electrode 20L, and a plurality of front side convex portions 11 and a
plurality of back side convex portions 12 are provided on the spacer 30L to provide conductivity.
The peripheral portion of the provided vibrating body 10 is fixed. The spacer 30U is fixed on the
peripheral portion of the vibrator 10, and the peripheral portion of the electrode 20U is fixed on
the spacer 30U. When a potential difference corresponding to the acoustic signal is generated
between the electrode 20U and the electrode 20L, an electrostatic force acts on the vibrating
body 10, and the vibrating body 10 vibrates in accordance with the acoustic signal. Then, a
sound corresponding to the vibration state (frequency, amplitude, phase) is generated from the
vibrating body 10. The generated sound passes through at least one of the electrodes 20 and is
emitted to the outside of the electrostatic speaker 1. [Selected figure] Figure 2
Electrostatic speaker
[0001]
The present invention relates to the structure of an electrostatic speaker.
[0002]
As the speaker, there is a speaker called an electrostatic speaker disclosed in Patent Document 1.
11-05-2019
1
This electrostatic speaker is a sheet-like vibration having conductivity, inserted between two
parallel flat electrodes facing each other at a distance and the two electrodes, and both ends
thereof being supported by a housing or the like. When a predetermined bias voltage is applied
to the vibrating body and the voltage applied to the electrodes is changed, the electrostatic force
acting on the vibrating body is changed, whereby the vibrating body is displaced. If this applied
voltage is changed according to the input acoustic signal, the vibrator repeats displacement (i.e.
vibrates) accordingly, and a reproduction wave corresponding to the acoustic signal is generated
from the vibrator. Then, the generated reproduction wave is radiated to the outside through the
hole opened in the flat electrode.
[0003]
Since the magnitude of the electrostatic force acting on the vibrating body of such an
electrostatic speaker is inversely proportional to the square of the distance between the vibrating
body and the flat electrode, in order to vibrate the vibrating body with high sensitivity, vibration
is generated. The distance between the body and the flat electrode may be narrowed. As
described above, as a technique for narrowing the distance between the vibrating body and the
flat electrode, there is an electrostatic type speaker disclosed in Patent Document 2. In the
vibrator of the electrostatic loudspeaker disclosed in Patent Document 2, a plurality of rowshaped convex portions are provided in parallel, and the vertex of the convex portion of the
vibrator is in contact with the flat electrode. According to this configuration, since the distance
between the vibrating body and the flat electrode becomes short, the vibrating body vibrates with
high sensitivity.
[0004]
JP, 11-178098, A JP, 2002-523994, A
[0005]
Now, according to the configuration disclosed in Patent Document 2, it is possible to improve the
sensitivity by shortening the distance between the facing electrodes.
However, if the distance between the electrodes is narrowed, the driving force by the acoustic
signal is increased, the opposing electrodes are also driven and vibrated, and distortion occurs in
the reproduction wave.
11-05-2019
2
[0006]
The present invention has been made under the above-described background, and it is an object
of the present invention to provide a technology that causes no problem in a reproduction wave
while vibrating a vibrating body with high sensitivity.
[0007]
In order to solve the problems described above, the present invention has a first electrode having
conductivity, a second electrode having conductivity and spaced apart from the first electrode,
and conductivity. Between the first electrode and the second electrode, a plurality of first convex
portions that are spaced apart from the first electrode and the second electrode and project to
the first electrode side, and toward the second electrode side The vibrator has a plurality of
protruding second protrusions, and a support member for supporting the vibrator. The first
protrusion has a cross-sectional shape perpendicular to the direction in which the first protrusion
protrudes. The second convex portion is a polygon or a closed curve, and the shape of a cross
section orthogonal to the projecting direction of the second convex portion is a polygon or a
closed curve, and the first convex portion and the second convex portion are at least Provided is
an electrostatic speaker characterized in that it is regularly arranged in two directions.
[0008]
In the present invention, the height of the first convex portion and the height of the second
convex portion may be the same.
In the present invention, the shape of the first convex portion may be the same as the shape of
the second convex portion.
In the present invention, the support member may support the vibrator without tension. Further,
in the present invention, the distance from the surface facing the first convex portion in the first
electrode to the tip of the first convex portion and the surface facing the second convex portion
in the second electrode The distance to the tip of the second convex portion may be equal. In the
present invention, an elastic member having elasticity may be provided between the first
electrode and the vibrator, and between the second electrode and the vibrator.
11-05-2019
3
[0009]
Further, in the present invention, the tip of the first convex portion is flat and parallel to the
surface of the first electrode facing the vibrating body, and the tip of the second convex portion
is flat and the second electrode is the flat. It may be parallel to the surface facing the vibrating
body. Further, in the present invention, the area of the flat tip end portion of each of the first
convex portions is the same as the area of the flat tip end portion of each of the second convex
portions, and the number of the first convex portions and the number of the first convex portions
are the same. The number of 2 convex parts may be the same.
[0010]
According to the present invention, it is possible to vibrate the vibrating body with high
sensitivity, and to cause no problem in the reproduction wave.
[0011]
[Example] Fig. 1 is a view schematically showing the appearance of an electrostatic speaker 1
according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of the
electrostatic speaker 1, and Fig. 3 is an electrostatic 3 is an exploded perspective view of the
speaker 1. FIG.
As shown in the figure, the electrostatic speaker 1 has a vibrating body 10, an electrode 20U and
an electrode 20L facing each other with the vibrating body 10 interposed therebetween, a spacer
30U and a spacer 30L. In the present embodiment, the configurations of the electrodes 20U and
20L are the same, and the configurations of the spacers 30U and 30L are the same. Therefore,
when there is no particular need to distinguish between the two, the descriptions of "L" and "U"
are described. Omit. Also, the dimensions of the respective components such as the vibrator and
electrodes in the drawing are different from the actual dimensions so that the shapes of the
components can be easily understood. Further, in the drawings, those in which • is described
in o means an arrow directed from the back to the front of the drawing, and those in which
x is described in o are the front of the drawing. It means the arrow from the back to the
back.
[0012]
11-05-2019
4
The vibrating body 10 is, for example, a film made of PET (polyethylene terephthalate,
polyethylene terephthalate), PP (polypropylene, polypropylene) or the like, with a metal film
deposited or coated with a conductive paint, and the thickness thereof is several μm to The
thickness is about several tens of μm. The vibrating body 10 has a flat peripheral portion, and
the front side convex portion 11 which protrudes on one surface side of the vibrating body 10
from a central plane parallel to the XY plane of the vibrating body 10 inside the peripheral
portion. And, there are a plurality of back side convex portions 12 projecting to the other surface
side of the vibrating body 10. In the vibrating body 10, the front side convex portions 11 and the
rear side convex portions 12 are regularly and alternately arranged in the X direction, and are
alternately and regularly arranged in the Y direction. Further, when the vibrating body 10 is cut
along the XZ plane, the cross section of the vibrating body 10 has a shape similar to that of a
square wave as shown in FIG. When cut along the cross-sectional shape of the front side convex
portion 11 and the rear side convex portion 12 of the vibrating body 10 is square.
[0013]
The electrode 20 is formed in a rectangular plate shape and has conductivity. Further, in the
electrode 20, in order to ensure sound transmission, a plurality of through holes 21 penetrating
from the front surface to the back surface of the electrode 20 are provided at predetermined
intervals. In the present embodiment, the lengths in the X and Y directions of the electrode 20
and the lengths in the X and Y directions of the vibrating body 10 are the same.
[0014]
The spacer 30 is formed of an insulator, and its shape is an annular shape having a corner as
shown in FIG. In the present embodiment, the lengths in the X direction and the Y direction of
the spacer 30 and the lengths in the X direction and the Y direction of the electrode 20 are the
same. Further, the heights of the spacers 30U and the spacers 30L in the Z direction are the
same.
[0015]
In the electrostatic speaker 1, the spacer 30L is fixed to the peripheral portion of the electrode
20L, and the peripheral portion of the vibrating body 10 is fixed on the spacer 30L. The vibrating
11-05-2019
5
body 10 is fixed to the spacer 30L in a state where no tension is applied. The spacer 30U is fixed
on the peripheral portion of the vibrator 10, and the peripheral portion of the electrode 20U is
fixed on the spacer 30U. In this configuration, the electrodes 20U and 20L are fixed to the
spacers 30U and 30L so as to face each other across the vibrating body 10, and the vibrating
body 10 is perpendicular to the electrode 20 in the space between the electrodes 20U and 20L. It
is supported so as to be able to vibrate in the Z direction.
[0016]
Next, the electrical configuration of the electrostatic speaker 1 will be described. As shown in FIG.
2, the electrostatic speaker 1 includes a transformer 50, an input unit 60 to which an acoustic
signal is input from the outside, and a bias power supply 70 for applying a DC bias to the
vibrator 10. The bias power supply 70 is connected to the vibrating body 10 and the middle
point on the output side of the transformer 50, and the two electrodes 20 are connected to one
end and the other end of the output side of the transformer 50, respectively. In this
configuration, when an acoustic signal is input to the input unit 60, voltages corresponding to
the input acoustic signal are applied to the electrode 20 and the vibrating body 10, respectively.
[0017]
When a potential difference is generated between the electrode 20U and the electrode 20L by
the applied voltage, an electrostatic force acts on the vibrating body 10 so as to be drawn to the
side of either electrode 20. That is, the vibrating body 10 is displaced in the Z direction
(deflection) according to the acoustic signal, and the displacement direction is successively
changed to become vibration, and the sound corresponding to the vibration state (frequency,
amplitude, phase) It originates from the vibrating body 10. The generated sound passes through
at least one of the electrodes 20 and is emitted to the outside of the electrostatic speaker 1.
[0018]
In comparison with the conventional electrostatic loudspeaker in which the electrostatic
loudspeaker 1 of the present embodiment and the vibrator 10 are flat, the vibrator 10 has the
front side convex portion 11 and the rear side convex portion 12 protruding toward the
electrode 20U and the electrode 20L. doing. For this reason, even if the distance between the
conventional electrostatic speaker, the electrode 20U and the electrode 20L is the same, the
11-05-2019
6
distance between the electrode 20 and the vibrating body 10 is closer than that of the flat
vibrating body at the tip of the convex portion. The sensitivity of the body 10 is high.
[0019]
Specifically, the distance from the center position of the vibrating body 10 to the electrode 20 in
the Z direction is d, the center position of the vibrating body 10 in the Z direction to the tip of the
front side convex portion 11, and the center of the vibrating body 10 in the Z direction Assuming
that the height from the position to the tip of the back side convex portion 12 is h, and the area
of the tip end portion of the front side convex portion 11 and the tip end portion of the back side
convex portion 12 is ΔS, the force F received by the vibrating body 10 from one electrode 20 is
It is expressed by Equation 1 and the total area S of the tips of the convex portions is expressed
by Equation 2. In Equation 2, n is the number obtained by summing the number of the front side
convex portions 11 and the number of the rear side convex portions 12.
[0020]
Next, power series expansion of the equation of equation 1 results in the equation of equation 3.
[0021]
Here, assuming that the area of the tip of the front side convex part 11 and the area of the tip of
the back side convex part 12 are equal, the area of the tip of the convex part on one side of the
vibrating body 10 is 1 / 2S, and the vibrating body 10 is The force F received from one of the
electrodes 20 is expressed by Equation 4.
[0022]
Here, if d = 0.5 mm, then F = 4 in the conventional flat vibrator without unevenness (h = 0 mm),
while in the present embodiment, d = 0.5 mm, h = 0. When it is 17 mm, F = 5.58, and it can be
seen that the sensitivity is improved by about 3 dB when a vibrating body having a convex
portion is used.
[0023]
Further, in the present embodiment, since the vibrating body 10 has unevenness, the rigidity of
the vibrating body 10 is higher than that of a flat conventional vibrating body.
11-05-2019
7
Therefore, even when tension is not applied to the vibrating body 10, the vibrating body 10 is
less likely to be wrinkled or slack, and the electrostatic force is uniformly applied to the vibrating
body 10, and the tone signal is correctly reproduced. .
In addition, since the rigidity is high due to the unevenness compared to a flat vibrator, the
vibrator 10 does not have wrinkles or slack when assembling the electrostatic speaker 1, and the
electrostatic speaker 1 can be easily assembled. it can.
[0024]
Further, in order to obtain the sensitivity obtained by the vibrating body 10 having the convex
portion with an electrostatic speaker having a flat vibrating body, it is necessary to narrow the
distance between the electrode 20U and the electrode 20L.
However, if the distance between the electrodes is narrowed, the driving force by the acoustic
signal from one of the electrodes 20 also affects the other electrode 20, the electrodes 20 are
also driven and vibrated, and distortion occurs in the reproduction wave. Become. On the other
hand, according to the present invention, the sensitivity of the vibrating body 10 is improved by
the convex portion of the vibrating body 10 even if the distance between the electrodes is
increased and the electrodes themselves are not driven. While vibrating, the drive of the
electrodes can be suppressed to prevent distortion of the emitted sound. In addition, even if the
distance between the opposing electrodes 20 is increased, the vibration pressure of the sound to
be output is increased because the vibration of the vibration body 10 is made to be sensitive with
high sensitivity compared to a flat vibration body. Is larger than an electrostatic speaker having a
flat vibrating body of the same size.
[0025]
[Modifications] Although the embodiment of the present invention has been described above, the
present invention is not limited to the above-described embodiment, and can be practiced in
various other forms. For example, the above-described embodiment may be modified as follows
to implement the present invention.
11-05-2019
8
[0026]
In the embodiment described above, the electrode 20 is a rectangular and plate-like member
having conductivity, but in the present invention, the electrode 20 is a porous and conductive
member such as a wire mesh or a conductive non-woven fabric. It may be.
[0027]
In the present invention, the vibrating body 10 may be one obtained by laminating a metal thin
film or one obtained by applying a high voltage to an insulating film.
[0028]
In the present invention, the shape of the convex portion in the vibrating body 10 is not limited
to the prismatic shape of the embodiment described above.
The shape of the convex portion may be conical, and the cross section thereof may be the shape
shown in FIG.
Also, the cross-sectional shape along the X-Y plane is a square, and the cross-sectional shape
along the X-Z plane (Y-Z plane) is a trapezoidal shape as shown in FIG. May be Further, the shape
when viewed from above is a square, and as shown in FIG. 4C, the shape of the cross section
along the XZ plane may be a sawtooth shape, and it is viewed from above The shape when it is
circular may be circular, and as shown in FIG. 4D, the shape of the cross section along the XZ
plane may be corrugated. Further, the cross-sectional shape along the X-Y plane is a square, and
the cross-sectional shape along the X-Z plane (Y-Z plane) is a step as shown in FIGS. 5 (a) to 5 (b).
The shape of the cross section along the X-Y plane may be circular, and the shape of the cross
section along the X-Z plane (Y-Z plane) may be as shown in FIG. It may be stepped. Further, in the
present invention, the height of the front side convex portion 11 and the height of the rear side
convex portion 12 may be different. In addition, it is preferable that the height of the front side
convex part 11 and the height of the back side convex part 12 are the same. The point is that, in
the vibrator 10, there is a convex portion that protrudes in the Z direction from a central plane
parallel to the XY plane, and in the state where no tension is applied to the vibrator 10, no
wrinkles or slack occurs in the vibrator 10 In such a case, the distance between the protrusions
and the height of the protrusions may be determined so that the vibrator 10 vibrates with high
sensitivity.
11-05-2019
9
[0029]
In the embodiment described above, the four sides of the peripheral portion of the vibrating body
10 are supported by the spacer 30U and the spacer 30L, but in the present invention, the four
sides of the vibrating body 10 are not supported by the spacer, and the vibrating body 10 is Only
the three sides, or only two sides, or only one side of the peripheral portion may be sandwiched
and supported by the spacer 30U and the spacer 30L.
[0030]
In the present invention, as shown in FIG. 6, elastic members 40U and 40L having the same
material and thickness and having elasticity may be inserted between the electrodes 20U and
20L and the vibrator 10.
Further, when the elastic member 40 is inserted into the electrostatic speaker 1, as shown in FIG.
7, the elastic member 40 may not enter between the convex portion and the convex portion
(concave portion). . The elastic member 40 has air permeability larger than that of the electrode
20, and preferably has an air permeability of 95% or more, for example. Further, as long as the
elastic member 40 is formed of an insulating material, it can take various forms such as a
sponge, a sheet, and a non-woven fabric. Thus, by providing the elastic member 40 between the
electrode 20 and the vibrating body 10, it is possible to support the vibrating body 10 and apply
appropriate elastic stress to the vibrating body 10.
[0031]
In the embodiment described above, the electrostatic speaker 1 has the electrode 20U and the
electrode 20L with the vibrating body 10 in between, and the acoustic signal is supplied to both
electrodes, but only one of the electrodes is acoustic. A signal may be supplied. Further, in this
configuration, the electrode to which the acoustic signal is not supplied may be replaced with a
rectangular and plate-like member having no conductivity. The point is that any configuration in
which electrostatic force acts on the vibrating body 10 in accordance with the input acoustic
signal may be used.
[0032]
In the present invention, the spacer 30U and the spacer 30L are opposed to each other and fixed,
11-05-2019
10
and the vibrator 10 is supported between the spacer 30U and the spacer 30L without tensioning
without being fixed to the spacer 30. You may
[0033]
It is a schematic diagram of the electrostatic-type speaker which concerns on one Embodiment of
this invention.
FIG. 2 is a cross-sectional view of the electrostatic speaker 1; FIG. 2 is an exploded perspective
view of the electrostatic speaker 1; It is the figure which showed typically the cross section of the
vibrating body 10 which concerns on the modification of this invention. It is the figure which
showed typically the cross section of the vibrating body 10 which concerns on the modification
of this invention. It is sectional drawing of the electrostatic-type speaker which concerns on the
modification of this invention. It is sectional drawing of the electrostatic-type speaker which
concerns on the modification of this invention.
Explanation of sign
[0034]
DESCRIPTION OF SYMBOLS 1 ... Electrostatic type speaker, 10 ... Vibrator, 11 ... Front side
convex part, 12 ... Back side convex part, 20U, 20L ... Electrode, 30U, 30L ... Spacer, 40U, 40L:
elastic member, 50: transformer, 60: input portion, 70: bias power supply
11-05-2019
11