U.S. patent application number 13/393360 was filed with the patent office on 2012-06-21 for electrostatic atomization device.
This patent application is currently assigned to Panasonic Corporation. Invention is credited to Bungo Imai, Hiroyasu Kitamura, Mikihiro Yamashita.
Application Number | 20120153055 13/393360 |
Document ID | / |
Family ID | 43706430 |
Filed Date | 2012-06-21 |
United States Patent
Application |
20120153055 |
Kind Code |
A1 |
Imai; Bungo ; et
al. |
June 21, 2012 |
ELECTROSTATIC ATOMIZATION DEVICE
Abstract
An electrostatic atomization device provided with a transformer
including primary and secondary coils. A switching element is
connected in series to the primary coil. A switching element drive
circuit provides the switching element with a pulse signal to
perform a switching operation and generate high voltage from the
secondary coil. A discharge unit including a discharge electrode
performs electrostatic atomization on liquid supplied to the
discharge electrode to generate charged fine liquid droplets when
high voltage generated by the secondary coil is applied to the
discharge electrode. The switching element drive circuit generates
a pulse signal having an oscillation frequency set so that the
transformer has drooping characteristics that prevent air discharge
from occurring between the discharge electrode and ground even when
load on the discharge unit varies and prevents the generation of
ozone having a predetermined concentration or greater when the
liquid undergoes electrostatic atomization.
Inventors: |
Imai; Bungo; (Osaka, JP)
; Kitamura; Hiroyasu; (Osaka, JP) ; Yamashita;
Mikihiro; (Shiga-ken, JP) |
Assignee: |
Panasonic Corporation
Osaka
JP
|
Family ID: |
43706430 |
Appl. No.: |
13/393360 |
Filed: |
September 13, 2010 |
PCT Filed: |
September 13, 2010 |
PCT NO: |
PCT/JP2010/066116 |
371 Date: |
February 29, 2012 |
Current U.S.
Class: |
239/690 |
Current CPC
Class: |
H02M 3/3381 20130101;
B05B 5/0255 20130101; B05B 5/053 20130101 |
Class at
Publication: |
239/690 |
International
Class: |
F23D 11/32 20060101
F23D011/32 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 25, 2009 |
JP |
2009-220458 |
Claims
1. An electrostatic atomization device comprising: a transformer
including a primary coil and a secondary coil; a switching element
connected in series to the primary coil of the transformer; a
switching element drive circuit that provides the switching element
with a pulse signal to perform a switching operation with the
switching element and generate high voltage from the secondary coil
of the transformer; and a discharge unit including a discharge
electrode, in which the discharge unit performs electrostatic
atomization on liquid supplied to the discharge electrode to
generate charged fine liquid droplets when the high voltage
generated by the secondary coil is applied to the discharge
electrode; wherein the switching element drive circuit generates a
pulse signal having an oscillation frequency set so that the
transformer has drooping characteristics that prevent air discharge
from occurring at the discharge electrode and prevent ozone having
a predetermined concentration or greater when the liquid undergoes
electrostatic atomization even when load on the discharge unit
varies.
2. The electrostatic atomization device according to claim 1,
wherein the discharge unit includes a ground electrode spaced apart
by a constant distance from the discharge electrode, the
electrostatic atomization device further comprising: a
rectification circuit connected between the secondary coil of the
transformer, the discharge electrode, and the ground electrode, in
which the rectification circuit rectifies the high voltage
generated by the secondary coil and applies the rectified high
voltage between the discharge electrode and the ground
electrode.
3. The electrostatic atomization device according to claim 1,
wherein the switching element drive circuit includes an oscillation
circuit that generates the pulse signal.
4. The electrostatic atomization device according to claim 3,
wherein the oscillation circuit includes a comparator.
5. The electrostatic atomization device according to claim 1,
wherein the switching element drive circuit includes: a fixed
resistor and a variable resistor connected in series; a comparator
having an inverting input terminal, a non-inverting input terminal
connected to a node between the fixed resistor and the variable
resistor, and an output terminal that outputs the pulse signal; and
a capacitor connected to the inverting input terminal of the
comparator; wherein the oscillation frequency is set by adjusting
resistance of the variable resistor.
6. The electrostatic atomization device according to claim 1,
wherein the switching element drive circuit includes: a first fixed
resistor and a second fixed resistor connected in series; a
comparator having an inverting input terminal, a non-inverting
input terminal connected to a node between the first fixed resistor
and the second fixed resistor, and an output terminal that outputs
the pulse signal; and a variable capacitance capacitor connected to
the inverting input terminal of the comparator; wherein the
oscillation frequency is set by adjusting capacitance of the
variable capacitance capacitor.
7. The electrostatic atomization device according to claim 1,
wherein the switching element drive circuit includes: a first
variable resistor and a second variable resistor connected in
series; a comparator having an inverting input terminal, a
non-inverting input terminal connected to a node between the first
variable resistor and the second variable resistor, and an output
terminal that outputs the pulse signal; and a variable capacitance
capacitor connected to the inverting input terminal of the
comparator; wherein the oscillation frequency is set by adjusting
at least one of resistances of the first and second variable
resistors and capacitance of the variable capacitance
capacitor.
8. The electrostatic atomization device according to claim 5,
wherein the switching element drive circuit includes: a totem pole
drive circuit connected to the output terminal of the comparator,
in which the totem pole drive circuit receives the pulse signal
from the comparator, amplifies the pulse signal, and provides the
amplified pulse signal to the switching element.
Description
TECHNICAL FIELD
[0001] The present invention relates to an electrostatic
atomization device.
BACKGROUND ART
[0002] Japanese Laid-Open Patent Publication Nos. 2006-334503 and
2007-21370 each describe a prior art example of an electrostatic
atomization device that generates charged fine water droplets of
nanometer size. In a state in which water is supplied to the distal
end of a discharge electrode by using capillary action, the
electrostatic atomization device applies high voltage to the
discharge electrode. When high voltage is applied to the discharge
electrode, the water supplied to the discharge electrode is
charged. This results in repetitive occurrence of Rayleigh breakups
and causes electrostatic atomization of the water. As a result, the
electrostatic atomization device generates charged fine water
droplets of nanometer size.
[0003] In such a type of electrostatic atomization device, a
self-oscillating flyback ringing choke converter (RCC) is used as a
switching power supply. The self-oscillating flyback RCC
self-oscillates a power MOSFET with a feedback coil wound around a
high voltage generation transformer. Accordingly, the
self-oscillating flyback RCC does not require a separate
oscillation circuit or the like and allows for a relatively small
circuit scale. Thus, the self-oscillating flyback RCC is often used
in electrostatic atomization devices. Further, for the output
control of a self-oscillating flyback RCC, feedback control is
often employed to readily activate a turnoff switch for the power
MOSFET in accordance with the output voltage.
[0004] In an electrostatic atomization device, air discharge occurs
when the voltage in a no-load state is too high. In such a case,
the electrostatic atomization device may not shift to electrostatic
atomization. Further, when too much water collects on the discharge
electrode, excessive current flows to the discharge electrode. In
such a case, a large amount of ozone is generated, and the ozone
concentration becomes high.
[0005] To prevent such a problem, it is desirable that a high
voltage generation circuit have power supply load characteristics
that suppress the generation of a large amount of ozone by lowering
the voltage applied to the discharge electrode when excessive
current flows.
DISCLOSURE OF THE INVENTION
[0006] It is an object of the present invention to provide an
electrostatic atomization device that prevents air discharge and
the generation of a large amount of ozone with low cost and without
the need for performing feedback control.
[0007] One aspect of the present invention is an electrostatic
atomization device provided with a transformer including a primary
coil and a secondary coil. A switching element is connected in
series to the primary coil of the transformer. A switching element
drive circuit provides the switching element with a pulse signal to
perform a switching operation with the switching element and
generate high voltage from the secondary coil of the transformer. A
discharge unit including a discharge electrode performs
electrostatic atomization on liquid supplied to the discharge
electrode to generate charged fine liquid droplets when the high
voltage generated by the secondary coil is applied to the discharge
electrode. The switching element drive circuit generates a pulse
signal having an oscillation frequency set so that the transformer
has drooping characteristics that prevent air discharge from
occurring between the discharge electrode and ground and prevent
ozone having a predetermined concentration or greater when the
liquid undergoes electrostatic atomization even when load on the
discharge unit varies.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an electric circuit diagram of an electrostatic
atomization device according to one embodiment of the present
invention;
[0009] FIG. 2 is a graph showing the drooping characteristics of a
transformer;
[0010] FIG. 3 is a graph showing the relationship of an air
discharge voltage and the drooping characteristics of the
transformer;
[0011] FIG. 4 is a graph showing the relationship of a regulated
generated ozone amount with respect to the output voltage and
output current of the transformer;
[0012] FIG. 5 is a graph showing the relationship of the drooping
characteristics of the transformer with respect to the air
discharge voltage and regulated generated ozone curve in the
present embodiment;
[0013] FIG. 6 is a detailed electric circuit diagram of the present
embodiment; and
[0014] FIG. 7 is an electric circuit diagram of an electrostatic
atomization device in a further example.
DESCRIPTION OF EMBODIMENTS
[0015] An electrostatic atomization device 1 according to one
embodiment of the present invention will now be discussed with
reference to the drawings.
[0016] FIG. 1 shows a high voltage generation circuit 2 of the
electrostatic atomization device 1. The high voltage generation
circuit 2 applies high voltage between a discharge electrode 3 and
ground, namely, a ground electrode 4, which form a discharge unit
arranged in the electrostatic atomization device 1. The discharge
electrode 3 and the ground electrode 4 are spaced apart from each
other by a predetermined distance. In a state in which water,
serving as liquid, is supplied to the distal end of the discharge
electrode 3, the high voltage generation circuit 2 applies high
voltage between the discharge electrode 3 and the ground electrode
4.
[0017] As a result, Coulomb force locally raises the liquid surface
of the water supplied to the distal portion of the discharge
electrode 3 into a conical form (Taylor cone). The raised conical
form of the water has a distal end at which charge is concentrated.
This increases the charge concentration, and the repulsive force of
the high concentration charges breaks up and scatters the water.
The breakup and scattering (Rayleigh breakup) is repeated and the
electrostatic atomization performed to generate a large amount of
charged fine water droplets of nanometer size including active
species.
[0018] In FIG. 1, a direct current power supply E, which generates
a DC voltage of 12 V, includes a positive terminal and a negative
terminal. A series circuit including a primary coil 5a of a high
voltage generation transformer 5 and a power MOSFET 6, which serves
as a switching element, is connected between the positive and
negative terminals of the direct current power supply E. Further, a
smoothing electrolytic capacitor 7 is connected between the
positive and negative terminals of the direct current power supply
E. The direct current power supply E supplies an oscillation
circuit 8, which serves as a switching element drive circuit, with
12 V of operational drive voltage.
[0019] The oscillation circuit 8 is supplied with drive voltage
from the direct current power supply E. The oscillation circuit 8
generates a pulse signal PS for activating and deactivating the
power MOSFET 6 and provides the pulse signal PS to a gate terminal
of the power MOSFET 6 via a resistor 9.
[0020] The power MOSFET 6 is activated or deactivated when its gate
terminal receives the pulse signal PS. The activation and
deactivation of the power MOSFET 6 intermittently energizes the
primary coil 5a of the high voltage generation transformer 5 with
the direct current power supply E. As a result, a secondary coil 5b
of the high voltage generation transformer 5 generates a secondary
voltage, which is a high voltage.
[0021] A half-wave rectification circuit including a diode D and a
capacitor 10 is connected between the two terminals of the
secondary coil 5b. The half-wave rectification circuit rectifies
the high secondary voltage from the secondary coil 5b and generates
an output voltage Vo, which has a high voltage (in the present
embodiment, 5 kV).
[0022] In the electrostatic atomization device 1, when the amount
of water on the discharge electrode 3 becomes small, it is known
that the Taylor cone becomes small and the distance from the distal
end of the Taylor cone to the ground electrode 4 becomes longer
thereby decreasing the discharge current (output current Io). In
the electrostatic atomization device 1, when the amount of water on
the discharge electrode 3 further decreases, discharging does not
occur between the water on the discharge electrode 3 and the ground
electrode 4. This results in a discharge (air discharge) occurring
between the discharge electrode 3 and the ground electrode 4. Thus,
electrostatic atomization is not performed.
[0023] On the other hand, when the amount of water on the discharge
electrode 3 of the electrostatic atomization device 1 becomes
large, it is known that the Taylor cone becomes large and the
distance from the distal end of the Taylor cone to the ground
electrode 4 becomes shorter thereby increasing the discharge
current. In the electrostatic atomization device 1, when the amount
of water on the discharge electrode 3 further increases, the
distance between the ground electrode 4 and water becomes extremely
short, and short-circuiting current thereby flows between the
ground electrode 4 and the water. Thus, mist having the desired
droplet diameter cannot be obtained. Further, a large amount of
ozone is generated. This increases the ozone concentration.
[0024] Accordingly, air discharge must be prevented. Further, the
generation of a large amount of ozone must be prevented when too
much water collects on the discharge electrode 3 and excessive
current flows. In other words, the output voltage Vo must be lower
than a voltage at which air discharge occurs (air discharge
voltage). Further, the output voltage Vo must be decreased when the
flow of the output current Io is excessive so that the ozone
concentration does not become high.
[0025] To satisfy these requirements, the electrostatic atomization
device of the present embodiment sets the output voltage Vo output
from the secondary coil 5b of the transformer 5 so as to prevent
air discharge and keep the amount of generated ozone less than or
equal to the regulated amount regardless of the amount of water on
the discharge electrode 3. The output voltage Vo is set in
accordance with the oscillation frequency and pulse width
(activation time) of the pulse signal PS provided from the
oscillation circuit 8 to the gate terminal of the power MOSFET
6.
[0026] In detail, the high voltage generation transformer 5
includes a large stray capacitance. Accordingly, the efficiency of
the high voltage generation transformer 5 decreases when the
oscillation frequency increases. Thus, due to the drooping
characteristics of the high voltage generation transformer 5 shown
in FIG. 2, in which the output voltage Vo decreases as the load
current (output current Io) increases, the output voltage Vo does
not increase when the output current Io is high.
[0027] In the present embodiment, the gradient of the drooping
characteristics is varied in accordance with the oscillation
frequency so as not to generate the output voltage Vo that
generates more ozone than the regulated amount. In other words, the
drooping characteristic line L1 shown in FIG. 2 is varied in
accordance with the oscillation frequency and pulse width
(activation time) of the pulse signal PS output from the
oscillation circuit 8.
[0028] In detail, to prevent air discharge, in the drooping
characteristics of the high voltage generation transformer 5, the
output voltage Vo must be set to be at least less than or equal to
an air discharge voltage Vd, for example, as shown in FIG. 3. Thus,
a margin voltage Vm is set taking into consideration variations and
independent differences of the high voltage generation transformer
5. In the drooping characteristics of the high voltage generation
transformer 5, the output voltage Vo is set to a voltage obtained
by subtracting the margin voltage Vm from the air discharge voltage
Vd.
[0029] The drooping characteristics shown in FIG. 3 are obtained by
setting the oscillation frequency and pulse width (activation time)
of the pulse signal PS output from the oscillation circuit 8.
[0030] FIG. 4 shows a regulated ozone amount generation curve L2.
The regulated ozone amount generation curve L2 indicates the output
voltage Vo and current Io, namely, power, for a predetermined
tolerable ozone generation amount. More specifically, as shown in
FIG. 4, with the regulated ozone amount generation curve L2 forming
a boundary, the ozone generation amount is greater than or equal to
the regulated amount in range A, and the ozone generation amount is
less than the regulated amount in range B. Hence, the drooping
characteristics (drooping characteristic line L1) of the high
voltage generation transformer 5 must be included in range B.
[0031] Accordingly, in the drooping characteristics (drooping
characteristic line L1) of the high voltage generation transformer
5 that avoids air discharge and prevents the ozone generation
amount from being greater than or equal to the regulated amount,
for example, as shown in FIG. 5, the output voltage Vo must at
least be greater than or equal to the air discharge voltage Vd
(including margin voltage Vm), and the power must be less than or
equal to the power set by the regulated ozone amount generation
curve L2. The drooping characteristics (drooping characteristic
line L1) shown in FIG. 5 is obtained by setting the oscillation
frequency of the pulse signal PS output from the oscillation
frequency.
[0032] In the present embodiment, the drooping characteristics for
the high voltage generation transformer 5 shown in FIG. 5 are
obtained through tests, experiments, and calculations. Further, in
the present embodiment, the oscillation frequency and pulse width
(activation time) of the pulse signal PS output from the
oscillation circuit 8 are set so that the electrostatic atomization
device 1 is operated based on the drooping characteristics shown in
FIG. 5.
[0033] Accordingly, the oscillation circuit 8 provides the power
MOSFET 6 with the pulse signal PS, which has the oscillation
frequency and pulse width (activation time) shown in FIG. 5, to
activate and deactivate the power MOSFET.
[0034] In this manner, the electrostatic atomization device 1
prevents air discharge and the generation of a large amount of
ozone regardless of the amount of water on the discharge electrode
3 that varies depending on the situation.
[0035] In addition, there is no need to detect the output voltage
Vo or output current Io and feedback-control the power MOSFET based
on such detected output voltage Vo or output current Io.
Accordingly, there is no need for a complicated and expensive
circuit that feedback-controls the output of the electrostatic
atomization device 1. Thus, the electrostatic atomization device 1
may be manufactured with less components and lower costs.
[0036] The high voltage generation circuit 2 of the electrostatic
atomization device 1 will now be discussed with reference to FIG.
6.
[0037] As shown in FIG. 6, the oscillation circuit 8 includes a
comparator 11. The comparator 11 includes a positive input terminal
(non-inverting input terminal) supplied with a divisional voltage
of a series circuit including a variable resistor Rb and a first
resistor R1, which are connected between the positive terminal and
negative terminal of the direct current power supply E. That is,
the series circuit, in which the variable resistor Rb and the first
resistor R1 are connected in series, is connected between the
positive terminal and negative terminal of the direct current power
supply E, and the voltage (divisional voltage) at a connection
point (node N1) of the variable resistor Rb and the first resistor
R1 is supplied as an input voltage Vi to the positive input
terminal of the comparator 11.
[0038] Further, the positive input terminal of the comparator 11 is
connected via a second resistor R2 to the output terminal of the
comparator 11. A negative input terminal (inverting input terminal)
of the comparator 11 is connected via a capacitor C1 to the
negative terminal of the direct current power supply E. Further,
the negative input terminal of the comparator 11 is connected via a
third resistor R3 to the output terminal of the comparator 11.
[0039] The oscillation circuit 8 using the comparator 11 generates
at its output terminal the pulse signal PS, which has a rectangular
wave and includes an oscillation frequency determined by the
resistance of the third resistance R3 and the capacitance of the
capacitor C1. Adjustment of the resistance of the variable resistor
Rb adjusts the pulse width (activation time), or frequency, of the
pulse signal PS.
[0040] In the present embodiment, the frequency and pulse width
(activation time) of the pulse signal PS are predetermined. That
is, as described above, the drooping characteristics of the voltage
generation transformer 5 shown in FIG. 5 are obtained beforehand
through tests, experiments, and calculations. Further, the
oscillation frequency and pulse width (activation time) of the
pulse signal PS output from the oscillation circuit 8 (comparator
11) are set so that the electrostatic atomization device 1 operates
in accordance with the drooping characteristics shown in FIG. 5. In
other words, the oscillation frequency and pulse width (activation
time) of the pulse signal PS are set so as to generate the output
voltage Vo that is less than or equal to the voltage at which air
discharge occurs (air discharge voltage) and so as to decrease the
output voltage Vo when excessive output current Io flows to prevent
the ozone concentration from becoming high.
[0041] In the present embodiment, the resistance of the variable
resistor Rb is adjusted to easily set the oscillation frequency and
pulse width (activation time) of the pulse signal PS. The output
terminal of the comparator 11 is connected via a fourth resistor R4
to a totem pole drive circuit 12. The totem pole drive circuit 12
includes an NPN transistor T1 and a PNP transistor T2. The base
terminals of the two transistors T1 and T2 are connected via the
fourth resistor R4 to the output terminal of the comparator 11.
[0042] The collector terminal of the NPN transistor T1 is connected
to the positive terminal of the direct current power supply E, and
the collector terminal of the PNP transistor T2 is connected to the
negative terminal of the direct current power supply E. The emitter
terminals of the two transistors T1 and T2 are connected to each
other. A connection point (node N2) of the two transistors T1 and
T2 are connected via the resistor 9 to the gate terminal of the
power MOSFET 6.
[0043] When the pulse signal PS output from the output terminal of
the comparator 11 has a high level, the NPN transistor T1 is
activated and the PNP transistor T2 is deactivated. As a result,
voltage having 12 V (high level) is applied to the gate terminal of
the power MOSFET 6. This activates the power MOSFET 6. Further, the
direct current power supply E energizes the primary coil 5a of the
high voltage generation transformer 5.
[0044] On the other hand, when the pulse signal PS output from the
output terminal of the comparator 11 has a low level (the pulse
signal PS is lost), the NPN transistor T1 is deactivated and the
PNP transistor T2 is activated. As a result, voltage having 0 V
(low level) is applied to the gate terminal of the power MOSFET 6.
This activates the power MOSFET 6 and de-energizes the primary coil
5a of the high voltage generation transformer 5.
[0045] The power MOSFET 6 is activated and deactivated in
accordance with the pulse signal PS output from the comparator 11.
This intermittently energizes the primary coil 5a of the high
voltage generation transformer 5. As a result, a high secondary
voltage is generated at the secondary coil 5b of the high voltage
generation transformer 5.
[0046] The half-wave rectification circuit, which includes the
diode D and the capacitor 10, rectifies the high secondary voltage
generated by the secondary coil 5b. This applies the output voltage
Vo of 5 kV between the discharge electrode 3 and the ground
electrode 4.
[0047] In the present embodiment, the oscillation frequency and
pulse width (activation time) of the pulse signal PS generated by
the comparator 11 are set to obtain the drooping characteristics of
the high voltage generation transformer 5, in which the output
voltage Vo is at least less than or equal to the air discharge
voltage and the power is less than or equal to the power of the
regulated ozone amount generation curve L2. This avoids the
occurrence of air discharge and prevents the ozone generation
amount from becoming greater than or equal to the regulated
amount.
[0048] Thus, the electrostatic atomization device 1 generates
output voltage Vo that is less than or equal to the voltage at
which air discharge occurs (air discharge voltage Vd) without
performing complicated feedback control and decreases the output
voltage Vo when excessive current Io flows. As a result, the
electrostatic atomization device 1 prevents the occurrence of air
discharge and the generation of a large amount of ozone regardless
of the amount of water on the discharge electrode 3 that varies
depending on the situation.
[0049] Additionally, in the present embodiment, the oscillation
circuit 8 is formed by the comparator 11. Thus, with a simple
circuit configuration, the pulse signal that is generated has an
oscillation frequency that is constantly stable in comparison with
the conventional LC oscillation circuit or the like.
[0050] Further, in the present embodiment, the oscillation
frequency of the pulse signal PS is easily adjusted just by
adjusting the resistance of the variable resistor Rb. This easily
obtains the desired drooping characteristics for the high voltage
generation transformer 5.
[0051] It should be apparent to those skilled in the art that the
present invention may be embodied in many other specific forms
without departing from the spirit or scope of the invention.
Particularly, it should be understood that the present invention
may be embodied in the following forms.
[0052] In the above-discussed embodiment, the cathode of the diode
D arranged in the rectification circuit is connected to the
secondary coil 5b of the transformer 5. However, as shown in FIG.
7, the cathode of the diode D arranged in the rectification circuit
may be connected to the capacitor 10. That is, when the high
voltage generation circuit 2 shown in FIG. 6 applies positive
output voltage Vo between the discharge electrode 3 and the ground
electrode 4, the high voltage generation circuit 2 shown in FIG. 7
applies negative output voltage Vo between the discharge electrode
3 and the ground electrode 4.
[0053] In the above-discussed embodiment, the resistance of the
variable resistor Rb connected to the positive input terminal of
the comparator 11 is adjusted to adjust the oscillation frequency
of the pulse signal PS. That is, the drooping characteristics of
the high voltage generation transformer 5 are varied. Instead, for
example, the first resistor R1 may be replaced by a variable
resistor or the capacitor C1 may be replaced by capacitor having a
variable capacitance. The resistance of the variable resistor or
the capacitance of the variable capacitance capacitor may be
changed to adjust the oscillation frequency of the pulse signal PS.
Further, at least one of the variable resistor Rb, the variable
resistor, and the variable capacitance capacitor may be changed as
required to adjust the oscillation frequency of the pulse signal
PS.
[0054] In the above-discussed embodiment, the power MOSFET 6 is
used as the switching element. However, a bipolar transistor may be
used instead as the switching element.
[0055] In the above-discussed embodiment, the half-wave
rectification circuit is used to rectify the secondary voltage
generated by the secondary coil 5b. However, the rectification
circuit may be a full-wave rectification circuit.
[0056] In the above-discussed embodiment, the oscillation circuit 8
is operated by the comparator 11. Instead, another oscillation
circuit configured to output a pulse signal that activates and
deactivates the switching element may be used.
[0057] In the above-discussed embodiment, the direct current power
supply E for 12 V is used. However, for example, a direct current
power supply that rectifies commercial power with a full-wave
rectification circuit may be used instead.
[0058] In the above-discussed embodiment, the present embodiment is
applied to an electrostatic atomization device that generates
charged fine water droplets by performing electrostatic atomization
on water. However, the present invention may also be applied to an
electrostatic atomization device that generates charged fine liquid
droplets of nanometer size by atomizing liquid other than water,
such as a skin lotion or a chemical.
[0059] In the above-discussed embodiment, the ground electrode 4 is
arranged facing toward the discharge electrode 3. However, the
arrangement and location of the ground electrode 4 are not
particularly limited. Further, a portion corresponding to the
ground electrode 4 may be formed by a housing of the electrostatic
atomization device 1.
[0060] The present examples and embodiments are to be considered as
illustrative and not restrictive, and the invention is not to be
limited to the details given herein, but may be modified within the
scope and equivalence of the appended claims.
* * * * *