JPS5220851

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DESCRIPTION JPS5220851
■ Manufacturing method of electrostatic type converter App. Akira 49-6785 ■ Japanese Patent
Application No. 44-99939 [phase] Application No. 44 (1969) December 11 @ inventor
Yoshimura Kamon Shin city Ogata Kamon Shin 1006 Matsushita Electric Industrial Co., Ltd. The
same place heres people same place O applicant Matsushita Electric Industrial Co., Ltd. Kadoma
city Oji Kadoma 1006 [present] agent patent attorney Toshio Nakao 1 person outside
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a principle diagram of a conventional
electrostatic transducer, FIG. 2 is a principle diagram of an electrostatic transducer obtained by
the method of the present invention, and FIG. It is the figure which showed the hysteresis curve
of the residual sound pressure with respect to the polarization voltage of the vibrating membrane
at the time of using.
DETAILED DESCRIPTION OF THE INVENTION The present invention does not require a DC bias
voltage using the ferroelectric phenomenon and the charge adsorption phenomenon of a
vibrating film such as a plastic film which tends to retain permanent charges, for example, an
electrostatic type such as a speaker, a microphone or a pickup The present invention provides a
method of manufacturing a converter. A conventional electrostatic transducer will be described
with reference to FIG. 1 using an electrostatic loudspeaker as an example. 1 is a vibrating film
made of a dielectric, 2 is vapor deposited or attached to one surface of the vibrating film 10 such
as aluminum or silver Movable electrode vibrating integrally with the vibrating membrane 1, 3 is
a punching metal provided in parallel with the vibrating membrane 1 so as to form a capacitor
with the movable electrode 2, metal or plating having a large number of small holes 4; An air
layer 3 is formed between the fixed electrode 3 and the vibrating film 1 with a spacer 5
interposed between the fixed electrode 3 and the vibrating film 1 so as to maintain a constant
gap in acoustic performance. [111111] In the speaker configured as described above, the
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diaphragm 1 vibrates by applying the alternating signal e superimposed on the high DC bias
voltage Eo between the both electrodes 2 and 3 to obtain the sound pressure P. This
conventional converter requires a high DC bias voltage Eo, requires a high voltage generator and
an amplifier when using a speaker, and requires a signal input terminal and a bias voltage
application terminal, which are structurally restricted. Also, the sensitivity becomes unstable due
to the ionization of the air layer due to the DC bias voltage, which causes a problem in practical
use. On the other hand, there is a disadvantage such as danger to the body due to the high
voltage being applied. . The present invention provides a method of manufacturing an
electrostatic converter which does not require such a high voltage DC bias voltage, and one
embodiment of the invention will be described with reference to FIGS. 2 and 3 in the case of a
speaker. Let's explain. 7 is a thin film vibrating film made of a dielectric material which is easily
charged with a static electrostatic charge and made of a plastic film such as Tetron Mylar or
polyimide, 8 is a movable electrode provided on one side of this vibrating film 7 in the same
manner as before. The fixed electrode has a plurality of small holes 10 facing the movable
electrode 9, and an air layer 11 is formed between the fixed electrode 9 and the vibrating film 7. .
After being incorporated in the same configuration as the conventional one as described above, a
polarization saturation voltage is applied between both the electrodes 8 and 9 so that the
residual charge of the vibrating film 7 is maximized. The permanent charge is charged by the
phenomenon and the charge adsorption phenomenon. FIG. 2 shows the direction of polarization
when this polarization voltage Ep is applied at room temperature, and even if this polarization
voltage Ep is removed, the vibrating film 7 is charged, which causes spontaneous polarization
and permanent surface charge Would be adsorbed.
When the polarization voltage Ep is applied for several seconds at room temperature and the
voltage Ep is removed and then the input signal e is applied, the hysteresis of the output sound
pressure is made of a tetron having a thickness of 15 μm [the 11111] [111111] ] EndPage:
shown in FIG. The sound pressure will generally be as shown by the dotted line in FIG. 3,
assuming that the plastic film is always charged with a slight negative charge, if this plastic film
is not naturally charged. However, the sound pressure follows a path of
1.fwdarw.2.fwdarw.3.fwdarw.4.fwdarw.5.fwdarw.6.fwdarw.2 due to the fact that natural charge is
generated and application of the polarization voltage. When the polarization voltage Ep is used
for a speaker, a saturation voltage Ep 'determined by the structure of the speaker, the space of
the air layer 110, and the material of the diaphragm 7 may be applied for several seconds. And
even if this saturation voltage is removed, a residual sound pressure of 98 dB can be obtained,
and the bias voltage becomes unnecessary. In the conventional manufacturing method of this
type of electrostatic converter, the diaphragm is held by the metal electrode, a voltage is applied
between the metal electrodes to charge the diaphragm, and then the diaphragm is made of metal.
It was peeled off from the electrode and this vibrating membrane was incorporated into a
transducer. However, such conventional manufacturing methods have the following
disadvantages. (1) The charge is more easily released than the charged vibrating film. That is, as
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described above, when the vibrating film is held by the metal electrode and the charged vibrating
film is peeled off from the metal electrode, triboelectric charging occurs and the charge on the
vibrating film is neutralized by the opposite sign charge on the metal electrode side. , The
amount of charge on the vibrating membrane decreases. Further, during the operation of
incorporating the charged vibrating membrane into the converter, dust, dust or the like is
adsorbed to the vibrating membrane, and the charge on the vibrating membrane F111 −− − −
− − + 1 escapes. (2) As a result of (1), the amount of charge on the vibrating membrane is
reduced to about + compared to that immediately after charging, and the sound pressure is thus
reduced by about 10 dB. (3) A dustproof jig is required so that dust, dirt and the like do not
adhere to the vibrating film. (4) Workability is bad. On the other hand, according to the
manufacturing method of the present invention, after incorporating the vibrating membrane into
the converter, a voltage is applied to charge the vibrating membrane with electric charges, so
that all the above-mentioned conventional drawbacks can be eliminated. As described above,
according to the manufacturing method of the present invention, there is an advantage that the
electric charge on the vibrating film hardly escapes, the sensitivity is improved, and the operation
becomes extremely easy.
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