WO2007010873A1 - Electrostatic atomizer - Google Patents

Abstract

An electrostatic atomizer having a discharge electrode, a counter electrode, a cooling source, a high voltage power supply, a current detector, and a controller. The cooling source cools the discharge electrode to form a water dew thereon. The power supply applies a high voltage for discharge between the electrodes. The detector detects a current flowing between the electrodes. The controller judges whether or not a discharge between the electrodes is a dry discharge, and the judgment is based on the current detected by the detector when the power supply applies a high voltage between the electrodes. The dry discharge is a discharge occurring when the quantity of dew on the discharge electrode is smaller than a specified quantity. When a discharge between the electrodes is the dry discharge, the controller temporarily raises cooling rate of the cooling source.

Description

 Specification

 Electrostatic atomizer

 Technical field

 The present invention relates generally to an electrostatic atomizer, and more particularly to an electrostatic atomizer that generates a mist of charged fine particles having a size of nanometer order.

 Background art

 [0002] An electrostatic atomizer of this kind can be found, for example, in the patent literature of Japanese Patent No. 3260150 (European Patent Publication No. 0 486 198 A1 or US Pat. No. 5,337,963). The prior art device described in this document comprises a liquid storage cartridge suitable for electrostatic spraying and high voltage means for applying an electrostatic potential to the liquid. The cartridge includes a capillary structure that extends into the cartridge to supply liquid from the cartridge to the spray output tube at the tip of the capillary structure by capillary action. The cartridge also includes means for providing a conductive path that allows charging of the liquid. When the high voltage means applies the potential to the liquid at the mouth of the spray output tube, a potential gradient is developed between the innermost and outer peripheral surfaces of the mouth, and the liquid flows across the end surface of the spray output tube toward the outermost surface. Pump out. As a result, the liquid is electrostatically ejected into a plurality of ligaments arranged so as to form a halo around the round.

 [0003] However, the prior art device requires refilling the cartridge with water. An electrostatic atomizer that can solve this problem has also been made separately by the present applicant (see Japanese Patent Application Publication No. 2006-122819). The atomizer includes a discharge electrode, a counter electrode disposed opposite to the discharge electrode, a cooling source that cools the discharge electrode to form dew as water thereon, and a discharge electrode between the electrodes. A high-voltage power supply for applying a high voltage. In this way, by cooling the discharge electrode to form dew, it is possible to save the trouble of supplying water.

[0004] By the way, the atomizer repeats Rayleigh splitting to realize electrostatic atomization. That is, when a high voltage is applied between the electrodes, negative charges are concentrated on the discharge electrode, and the water held at the tip of the discharge electrode rises like a cone to form a tiller cone. Negative charge is te When concentrated at the tip of the cone, the repulsive force of the high-density electric charge causes Rayleigh splitting, splitting and scattering the water of the tiller cone. Thus, in an atomizer that realizes electrostatic atomization by repeating Rayleigh splitting, a high voltage is applied between the electrodes so that a discharge is generated under the condition that an appropriate amount of dew is formed on the discharge electrode. It is important to apply. If a discharge (dry discharge) occurs when the amount of dew on the discharge electrode is below the proper amount, a large discharge current will flow between the electrodes. When such a dry discharge occurs continuously, the discharge electrode is subjected to great stress, and its life is significantly shortened.

 Disclosure of the invention

 [0005] Accordingly, an object of the present invention is to prevent the continuous generation of dry discharge in addition to saving the labor of replenishing water.

 [0006] The electrostatic atomizer of the present invention includes a discharge electrode, a counter electrode, a cooling source, a high-voltage power supply, a current detector, and a controller. The counter electrode is disposed to face the discharge electrode. The cooling source cools the discharge electrode and forms dew as water thereon. The power source applies a high voltage for discharge between the electrodes. The detector detects a current flowing between the electrodes. The controller determines whether or not the discharge between the electrodes is a dry discharge based on the current detected by the detector when the power supply applies a high voltage between the electrodes. The dry discharge is a discharge when the amount of dew on the discharge electrode is less than a specified amount. When the discharge between the electrodes is the dry discharge, the controller temporarily increases the cooling rate of the cooling source. Thus, by temporarily increasing the cooling rate in the case of the dry discharge, it is possible to prevent the ozone from being generated by quickly returning to the normal discharge.

 [0007] Preferably, the controller monitors a time when the current detected by the detector exceeds a threshold current, and when the time exceeds the threshold time, the discharge between the electrodes is the dry discharge. Is determined. This configuration is advantageous in that the detection accuracy of dry discharge can be increased.

[0008] In the case of the dry discharge, the controller may stop the cooling source and the power source for a predetermined time, and then start the cooling source to temporarily increase the cooling rate. In this configuration, when a large amount of dew is formed on the discharge electrode, the large amount of dew can be reduced. Therefore, even when a large amount of dew is formed on the discharge electrode not only in the case of dry discharge, it can be quickly returned to normal discharge.

 [0009] In the case of the dry discharge, the controller may increase the cooling rate stepwise. According to this configuration, it is possible to prevent a large amount of dew from being formed on the discharge electrode.

[0010] In the case of the dry discharge, the controller may increase the cooling rate to a maximum cooling rate. According to this configuration, it is possible to quickly return to normal discharge.

 [0011] When the controller stops the cooling source for the predetermined time, the controller may step down the cooling rate and then stop the cooling source. In this case, stress on the cooling source can be reduced.

 Brief Description of Drawings

 [0012] Preferred embodiments of the invention are described in further detail. Other features and advantages of the present invention will be better understood with reference to the following detailed description and accompanying drawings.

FIG. 1 is a schematic diagram of an embodiment according to the present invention.

 FIG. 2 is an operation flow diagram of the embodiment.

 FIG. 3 is an explanatory diagram of discharge current control in the enhanced embodiment of FIG.

 [Figure 4] An example of the discharge current waveform in the case of overdischarge due to overshoot.

 [Figure 5] Illustrates the discharge current waveform for dry discharge.

 FIG. 6 is an explanatory diagram of control for preventing ozone generation.

 FIG. 7 is an operation flowchart of another modified embodiment.

 FIG. 8 illustrates a Peltier module stop operation according to an alternative embodiment of FIG.

 BEST MODE FOR CARRYING OUT THE INVENTION

[0013] FIG. 1 illustrates one embodiment (ie, an electrostatic atomizer) according to the present invention. The electrostatic atomizer includes a discharge electrode 1, a counter electrode 2, a cooling source 3, a high voltage power supply 4, a DC power supply 5, and a controller 6.

The discharge electrode 1 has, for example, a tip 11 having a teardrop shape, and receives a negative or positive high voltage (for example, −4.6 kV) from the high-voltage power supply 4 during discharge. The counter electrode 2 is formed in, for example, a ring shape whose inner peripheral edge functions as a substantial electrode, and a predetermined distance from the tip 11 of the electrode 1 Oppositely arranged at a distance. The electrode 2 is connected to the ground.

 [0015] The cooling source 3 includes, for example, a Peltier module 30 and heat radiating fins 31, and cools the discharge electrode 1 to a temperature equal to or lower than the dew point temperature of the surrounding air to form dew as water thereon. The base of electrode 1 is connected to the cold side of module 30 and fin 31 is connected to the hot side of module 30.

 [0016] The high-voltage power source 4 includes, for example, a high-voltage generator 40, a voltage detector 41, and a current detector 42. The generator 40 generates a high voltage for discharge according to the ON control signal from the controller 6 and applies it between the electrodes 1 and 2, and stops generating the high voltage according to the OFF control signal from the controller 6. To do. The detector 41 detects a voltage (discharge voltage) applied between the electrodes 1 and 2, and outputs a detection voltage signal (voltage Vv) to the controller 6 (AD input). The detector 42 detects a current (discharge current) flowing between the electrodes 1 and 2, and outputs a detection current signal (voltage Vi) to the controller 6 (AD input).

 The DC power supply 5 is constituted by, for example, a DCZDC converter 50 and applies a voltage adjusted according to a duty control signal from the controller 6 to the Peltier module 30. The power supply 5 supplies a voltage (V +) to the high-voltage power supply 4.

 The controller 6 includes, for example, a microcomputer (microcomputer), a storage device, an AZD converter, and the like. Based on the voltage and current from the detectors 41 and 42, the output of the high-voltage power source 4 and the DC power source 5 Control the output of. Both power supplies are controlled in the start-up mode (S10-S11 in FIG. 2), normal discharge determination mode (S20-S21), discharge current control mode (S30), dry discharge restriction mode (S40-S49), and the like.

 [0019] In the start-up mode (during start-up), since the discharge electrode 1 is not cooled and dew is not formed on the electrode 1, the controller 6 outputs the output voltage of the DC power source 5 (converter 50). An initial duty control signal is output to the power source 5 for a predetermined time so that the predetermined initial voltage is reached, thereby adjusting the cooling rate of the Peltier module 30 to the initial cooling rate and Form dew. Preferably, the predetermined time is set to a time of 1 minute or longer (for example, several minutes).

[0020] After the predetermined time has elapsed, the controller 6 operates in a normal discharge determination mode. In other words, the controller 6 is configured such that the high voltage power source 4 (high voltage generator 40) Output ON control signal to power supply 4 to apply between 1 and 2. Subsequently, the controller 6 determines whether or not the discharge between the electrodes 1 and 2 is a normal discharge based on the value of the current detected by the current detector 42. If the discharge between the electrodes 1 and 2 is a normal discharge, the controller 6 operates in a discharge current control mode of feedback control, and if not, the controller 6 operates in a dry discharge restriction mode. Details of the normal discharge determination will be described later.

 [0021] In the discharge current control mode, the controller 6 outputs an ON control signal to the power supply 4 so that the high-voltage power supply 4 generates a high voltage and applies it between the electrodes 1 and 2, and at the same time, LA 6 outputs a duty control signal to the power source 5 so as to adjust the cooling rate of the Peltier module 30 by adjusting the output voltage of the DC power source 5 based on at least the current detected by the current detector 42. . As a result, when dew as water is formed on the discharge electrode 1 and a discharge occurs between the electrodes 1 and 2, the water on the electrode 1 is pulled toward the counter electrode 2 and the tailor cone is formed. Forming and Rayleigh splitting occur at the tip of the tailor cone, and a mist of charged fine particles of nanometer order is generated.

In order to stably generate mist, it is necessary to adjust the amount of dew formed on the discharge electrode 1 to an appropriate amount (a prescribed amount within a prescribed range) determined at the design stage. If the amount of dew on the electrode 1 is far below the specified amount, the discharge will occur between the electrodes 1 and 2 but not between the water and the counter electrode 2, leading to the generation of ozone. Conversely, if the amount of dew on electrode 1 is much greater than the specified amount, a short circuit current will flow between water and counter electrode 2 and it will not be possible to generate mist of charged particles of the desired size. . Therefore, in the discharge current control mode, the relationship between the current (discharge current) detected by the current detector 42 and the length of the tailor cone is used. That is, if the amount of dew on the electrode 1 is small, the length of the tailor cone is shortened, and the value of the current detected by the detector 42 becomes small. On the other hand, if the amount of dew on the electrode 1 is large, the tailor cone is small. The length of the current becomes longer, and the value of the current detected by the detector 42 becomes larger. Thus, by detecting the current flowing between the electrodes 1 and 2 with the detector 42, the length (dew amount) of the tailor cone can be known. For this reason, if the current value detected by the detector 42 is smaller than the predetermined reference current value, the controller 6 increases the output voltage of the DC power source 5 to increase the cooling rate of the Peltier module 30. Duty system Output control signal to power supply 5. Conversely, if the value of the current detected by the detector 42 is greater than the value of the reference current, the controller 6 supplies the duty control signal to the power supply 5 so as to lower the cooling rate by reducing the output voltage of the power supply 5. Output to 5.

 [0023] The normal discharge determination will be described in detail. When the controller 6 determines whether or not the discharge between the electrodes 1 and 2 is a normal discharge based on the current value detected by the current detector 42, the controller 6 Use a larger threshold Imax. That is, if the current value detected by the detector 42 is smaller than a predetermined threshold value Imax, the controller 6 forms a dew on the discharge electrode 1 with a specified amount of discharge force between the electrodes 1 and 2. It is determined that the discharge is normal when it is discharged, and operates in the discharge current control mode. In this case, deterioration and wear of the electrode 1 can be prevented. By the way, even when the prescribed amount of dew is not formed on the electrode 1, the value of the current detected by the detector 42 may be smaller than the threshold value Imax. Since the current flowing between 1 and 2 is not large, the problem of electrode 1 deterioration and wear does not occur.

 On the other hand, if the value of the current detected by the detector 42 is equal to or greater than the threshold value Imax, the controller 6 determines that the discharge between the electrodes 1 and 2 is not normal discharge, and in the dry discharge restriction mode. Operate. That is, the controller 6 shuts off the power sources 4 and 5 for a predetermined dehumidification time to reduce, for example, a large amount of dew formed on the discharge electrode 1 to almost zero, for example due to high ambient humidity. . Subsequently, the controller 6 temporarily outputs an ON control signal to the power source 4 so that the high voltage power source 4 generates a high voltage and applies it between the electrodes 1 and 2, and is detected by the current detector 42. Based on the current value, it is determined whether or not the discharge power between electrodes 1 and 2 is a dry discharge when the amount of dew on electrode 1 is less than the specified amount.

[0025] Specifically, the controller 6 discharges between the electrodes 1 and 2 if the value Idd of the current detected by the current detector 42 is equal to or slightly smaller than the threshold value Idd. Is determined to be dry discharge, and control is performed to regulate dry discharge. That is, the controller 6 stops the high-voltage power supply 4 and raises the cooling rate of the Peltier module 30 to the maximum cooling rate and holds the state for a predetermined maximum cooling duration. Thereby, dew is formed on the discharge electrode 1 in a short time. Subsequently, the controller 6 temporarily outputs an ON control signal to the power supply 4 so that the power supply 4 generates a high voltage and applies it between the electrodes 1 and 2. If the current value detected by the detector 42 is smaller than the threshold value Idd, the controller 6 determines that the discharge between the electrodes 1 and 2 is a normal discharge and operates in the discharge current control mode. Conversely, if the value of the current detected by the detector 42 is equal to or greater than the threshold value Idd, the controller 6 indicates that the discharge between the electrodes 1 and 2 is a dry discharge, and the force also forms an ambient environmental force. It is determined that the temperature and humidity are above the cooling capacity of the module 30, and power supplies 4 and 5 are turned off. Note that the controller 6 may be restarted in the startup mode after a predetermined time has elapsed.

[0026] On the other hand, if the value of the current detected by the detector 42 is smaller than the threshold value Idd, the controller 6 determines that the discharge between the electrodes 1 and 2 has become a normal discharge, and controls the discharge current. Operate in mode.

Next, the operation of the present electrostatic atomizer will be described with reference to FIG. When the atomizer controller 6 operates in the start-up mode, the Peltier module 30 operates at the initial cooling rate for a predetermined time (SIO—Sl). After a predetermined time has elapsed, the controller 6 operates in the normal discharge determination mode, and the high voltage power source 4 generates a high voltage and applies it between the electrodes 1 and 2 (S20). Subsequently, the controller 6 determines whether or not the discharge between the electrodes 1 and 2 is a normal discharge based on the current value (I) detected by the current detector 42 (S21). If the discharge between the electrodes 1 and 2 is normal discharge (KImax), the controller 6 operates in the discharge current control mode (S30). Otherwise (I≥Ima _X ), the controller 6 operates in dry discharge regulation mode

[0028] In the dry discharge restriction mode, the controller 6 stops the power sources 4 and 5 during the dehumidifying time (S40-S41). Subsequently, the high-voltage power supply 4 generates a high voltage and applies it between the electrodes 1 and 2 (S42), and the controller 6 determines whether the voltage between the electrodes 1 and 2 is based on the current value detected by the current detector 42. It is determined whether or not the power is a dry discharge (S43). If the discharge force between the electrodes 1 and 2 is not S dry discharge (KIdd), the controller 6 operates in the discharge current control mode (S30). If the discharge between the electrodes 1 and 2 is a dry discharge (I≥Idd), the controller 6 stops the power supply 4 (S44), increases the cooling rate of the Peltier module 30 to the maximum cooling rate (S4 5), This state is maintained for the maximum cooling duration (S46). Subsequently, the controller 6 determines whether or not the dry discharge is eliminated (S47-S48). If dry discharge is eliminated (KIdd), the controller 6 operates in the discharge current control mode (S30). Otherwise (1≥1 dd), the controller 6 stops the power supplies 4 and 5 (S49).

 [0029] In one enhanced embodiment, the controller 6 adjusts the output voltage of the DC power supply 5 based on the voltage detected by the voltage detector 41 and the current detected by the current detector 42. A duty control signal is output to the power source 5 so that the cooling rate of the Peltier module 30 is adjusted. Here, the discharge voltage (V (m)) is selected in advance from a plurality of voltage ranges shown in Table 1 by the user. For this reason, if the voltage between the electrodes 1 and 2 changes, the value of the discharge current indicating the amount of dew formed on the discharge electrode 1 also changes, so the voltage (discharge voltage) detected by the detector 41 Further, as shown in Table 1, the predetermined median value Im id (n) (reference current value), upper limit value Imax (n) (threshold value Imax) and lower limit value Imin (n) are It is selected for each discharge voltage V (m). Therefore, the controller 6 outputs the duty control signal to the power source 5 so that the current detected by the detector 42 becomes a median value corresponding to the voltage detected by the detector 41.

 [0030] [Table 1]

Also, as shown in FIG. 3, the controller 6 sets the cooling rate of the Peltier module 30 to the median value based on the voltage detected by the voltage detector 41 and the current detected by the current detector 42. A duty control signal is output to the DC power supply 5 so as to make it asymptotically approach the cooling rate corresponding to. Specifically, after stabilization of each block of the electrostatic atomizer, the controller The troller 6 averages the voltage and current detected by the detectors 41 and 42 for each specified period At. For example, when each block is stable (t0), the controller 6 starts to acquire voltage and current from the detectors 41 and 42, and at the time tl after the period At, the average value of the voltage value and the average of the current value The values are calculated as discharge voltage V (l) and discharge current 1 (1), respectively. Similarly, the controller 6 calculates the discharge voltage V (2) and the discharge current 1 (2) at time t2. At this point, the controller 6 calculates the difference in discharge current between tl and t2 (Δ Ι (2) = Ι (2) -1 (1), and from Table 1, the median ( Imid (n), t = tl) and read the difference from 1 (2) (A ld (2) = Imid (n) -1 (2

 {t = tl}

;)) Is calculated. Subsequently, the controller 6 calculates an increment (AD (2) = PaX Ald (2) −Pb X Δ1 (2) for the duty (D (3;)) for the power source 5 between t2 and t3. , Tl and t2 duty (D (2), t2 and t3 duty (D (3) = D (2) + AD (2). Pa and Pb are parameters, D (2), D (3), etc. correspond to any of D1-D256 obtained by dividing 0—100% duty into 256. After t3, controller 6 also has duty increment (AD (m) = PaX A ld (m) −Pb XA l (m)) is calculated and a duty control signal is output to the power source 5.

 [0032] When calculating the duty increment Δ D (m), a correction function F {D (m-1)} corresponding to the value of the previous increment Δ D (ml) is used, that is, (Pa XA ld (m)-Pb X Δ I (m) XF {D (m-1)} may be used to calculate the increment AD (m), and the function F {D (m)} When m-1) is low, it has a small value, and when D (ml) is high, it has a large value, which makes it possible to weight the entire duty.When the duty is low, the voltage to the Peltier module 30 Since the cooling temperature Δ 放電 of the discharge electrode 1 is also low, dew is likely to be formed on it, so by setting the value of the correction function to 0.5, for example, excessive dew is formed. Conversely, when the duty is high, the cooling temperature ΔΤ is large and it is difficult to form dew, so the value of the correction function is set to 2, for example, to increase the rate of change. For example, Δ 室温 is 5 ° C when the room temperature is 25 ° C and dew point is 20 ° C, and ΔΤ is when the room temperature is 25 ° C and dew point is 10 ° C. Is 15 ° C.

[0033] In one preferred embodiment, the controller 6 determines whether the discharge between the electrodes 1 and 2 is a dry discharge based on the current detected by the current detector 42 even in the discharge current control mode. If the discharge is a dry discharge, the dry discharge regulation mode is determined. It operates under the same control as the control (S40-S49). Specifically, in the case of normal discharge, the discharge current flowing between electrodes 1 and 2 falls within a range approximately twice the discharge current (for example, 8 / z A) corresponding to the default discharge voltage, for example. . Therefore, the controller 6 determines that the discharge between the electrodes 1 and 2 is dry discharge when the current detected by the detector 42 exceeds the upper limit of the range. Dry discharge also occurs during continuous operation under the discharge current control mode.For example, Peltier module 30 failure, DC power supply 5 failure, dust adhering to discharge electrode 1 or surrounding environment (especially temperature and humidity) Occurs when dew does not form on discharge electrode 1 due to factors such as changes in In the electrostatic atomizer shown in Fig. 1, when dry discharge occurs during the discharge current control mode, the amount of dew is reduced according to the large discharge current due to the dry discharge, so the dry discharge cannot be returned to normal discharge. . According to this preferred embodiment, the dry discharge is returned to the normal discharge by determining whether or not the discharge between the electrodes 1 and 2 is a dry discharge based on the current detected by the detector 42. Can do.

In one enhanced embodiment, when the current detected by current detector 42 exceeds a predetermined threshold under the discharge current control mode, controller 6 determines that the discharge between electrodes 1 and 2 is a dry discharge. A distinction is made between whether there is overdischarge due to overshoot or not. In the discharge current control mode, as shown in FIG. 4, the force overshoot that is adjusted to Imid within the range of the current I force Imax and Imin detected by the detector 42 is, for example, the discharge current control mode. It may occur in the initial stage, etc., and may exceed the current I force threshold Imax. In such a case, if the control in the discharge current control mode is continued, the current I falls within the above range. On the other hand, as shown in FIG. 5, even in the case of dry discharge, the current I exceeds the threshold value Imax, but in this case, even if the control in the discharge current control mode is continued, the current I Unless it is formed on the discharge electrode 1, it does not return to the above range. Therefore, when the current I force S threshold Imax is exceeded, it is necessary to distinguish whether the discharge between electrodes 1 and 2 is an overdischarge due to a force overshoot which is a dry discharge. In this embodiment, the controller 6 measures the time exceeding the current I force S threshold Imax. If the time is longer than the threshold time Ta for determining dry discharge and overdischarge, the controller 6 determines that the discharge between the electrodes 1 and 2 is dry discharge, and the control is the same as in the dry discharge restriction mode control. Operates with control. On the other hand, if the time is within the threshold time Ta, the controller 6 Is determined to be an overdischarge due to overshoot, and control of the discharge current control mode is continued. The threshold time Ta is set to a time shorter than the time B in FIG. 5 that is longer than the time A in FIG. For example, if the A time is set to 30 seconds or less, the threshold time Ta is set to about 1 minute.

 [0035] In one modified embodiment, as shown in FIG. 6, the controller 6 is configured to prevent the current I 1S detected by the detector 42 from exceeding the threshold value Ith larger than the threshold value Imax for preventing ozone generation. Measure. When the time is longer than the threshold time Tb for preventing ozone generation, the controller 6 stops the high piezoelectric source 4 for a predetermined stop time for preventing ozone generation. The threshold time Tb is set to a time shorter than the threshold time Ta, for example. In this case, this embodiment can be combined with the embodiments of FIGS. 4 and 5, and the stop time is set based on the threshold value Ith, the threshold time Ta, and the threshold time Tb. Specifically, if the threshold time Ta and the threshold time Tb are long, the amount of dew is reduced. Therefore, in the case of dry discharge, the time for reducing the amount of dew can be shortened. Is set. If the threshold time Ta and the threshold time Tb are short, the amount of dew may be high, so the pause time is set to a few minutes.

In another modified embodiment, as shown in FIG. 7, the controller 6 operates in the normal discharge determination mode after the start-up mode (not shown) and determines whether or not it has the power to shift to the discharge current control mode. Determine (S120). If the mode does not enter the discharge current control mode (NO at SI 20), the power sources 4 and 5 are suspended for a predetermined time (S121), and the process returns to step S120. When shifting to the discharge current control mode (YES in S120), the controller 6 operates in the discharge current control mode (S1 30) .For example, the current detected by the current detector 42 is output at predetermined intervals such as by interruption. It is determined whether or not the threshold value is equal to or greater than Imax (S100). If the current is less than the threshold value Imax, the process returns to step S130. If the current is equal to or greater than the threshold value Imax, the controller 6 operates in the dry discharge restriction mode. That is, the controller 6 stops the power supplies 4 and 5 during the dehumidifying time (S140-S141). Subsequently, the controller 6 increases the cooling rate of the Peltier module 30 to the maximum cooling rate with a rising rate faster than the normal control (see the broken line), and at the same time, supplies the electrode via the high-voltage power source 4 every ΔΤ. A high voltage is generated between 1 and 2, and based on the current I detected by the detector 42 within a predetermined elapsed time or a predetermined number of determinations, It is determined whether the live discharge has been eliminated (S 142). If the dry discharge is eliminated (if smaller than the current I force S threshold Idd), the process returns to step S130. If the dry discharge is not eliminated by the predetermined elapsed time or the predetermined number of determinations (I≥Idd), the power supplies 4 and 5 are suspended for the predetermined time (S143), and the operation returns to the start mode.

 [0037] Thus, by increasing the rising rate, the amount of dew can be quickly increased to an appropriate amount, and the number of occurrences of dry discharge can be reduced. However, if the amount of dew is excessive, the current detected by the current detector 42 becomes so large that it cannot be distinguished from dry discharge. Therefore, the rising rate is adjusted in an environment where dew is likely to form (about 40 ° C, 90% RH). In this environment, for example, when a maximum voltage is applied to the Peltier module 30, dew is formed: If the A discharge current takes 15 seconds to flow between electrodes 1 and 2, then the rising rate is The starting power of is set to reach the maximum cooling rate after about 60 seconds. In this case, the time of step S143 is set based on the environment where dew formation is difficult (about 40 ° C, 15% RH). That is, if maximum voltage is applied to module 30 and dew is formed and it takes about 3 minutes to allow 1 A discharge current to flow between electrodes 1 and 2, the time for S143 is about 3 minutes. Is set. In the case of step S140, the high-voltage power supply 4 (high-voltage generator 40) is turned off mainly to prevent the generation of ozone, and the module 30 is turned off in consideration of the excessive amount of dew, but the dry discharge If the occurrence is obvious, you can keep module 30 on! /.

 [0038] In one alternative embodiment, as shown in FIG. 8, when the controller 6 turns off the Peltier module 30, for example in steps S40, S49, S121, S140 or S143, the controller 6 Decrease the cooling rate in steps (eg about every 3 seconds ΔΤ) and then shut down module 30. According to this embodiment, since the stress on the module 30 can be reduced, its life can be extended.

[0039] In another alternative embodiment, the controller 6 further considers the voltage of the Peltier module 30 when the controller 6 determines whether a dry discharge has occurred. If the controller 6 operates in the discharge current control mode in the case of dry discharge, the current detected by the current detector 42 shows fluctuation, and the module 30 shows voltage fluctuation according to the fluctuation of the current. Therefore, if the width of the voltage fluctuation is, for example, about 0.3 V, the module 3 If the actual voltage of 0 continues below 0.3V, it can be determined that a dry discharge has occurred.

 DETAILED DESCRIPTION OF THE INVENTION The present invention has been described in terms of several preferred embodiments. Various modifications and variations can be made by those skilled in the art without departing from the true spirit and scope of the invention.

Claims

The scope of the claims  [1] a discharge electrode;  A counter electrode disposed opposite to the discharge electrode;  A cooling source that cools the discharge electrode to form dew as water thereon;  A high voltage power source for applying a high voltage for discharge between the electrodes;  A current detector for detecting a current flowing between the electrodes;  Based on the current detected by the detector when the power supply applies a high voltage across the electrodes, the discharge between the electrodes is less than the specified amount of dew on the discharge electrodes. Determining whether or not the discharge is a dry discharge, and when the discharge between the electrodes is the dry discharge, a controller for temporarily increasing the cooling rate of the cooling source;  An electrostatic atomizer comprising:  [2] The controller monitors the time when the current detected by the detector exceeds the threshold current, and determines that the discharge between the electrodes is the dry discharge when the time exceeds the threshold. The electrostatic atomizer according to claim 1 to be determined. [3] The controller according to claim 1, wherein, in the case of the dry discharge, the controller stops the cooling source and the power source for a predetermined time, and subsequently activates the cooling source to temporarily increase the cooling rate. Electrostatic atomizer.  [4] In the case of the dry discharge, the controller stops the cooling source and the power source for a predetermined time, and subsequently activates the cooling source to temporarily increase the cooling rate. Electrostatic atomizer.  5. The electrostatic atomizer according to claim 1, wherein, in the case of the dry discharge, the controller increases the cooling rate stepwise.  6. The electrostatic atomizer according to claim 2, wherein, in the case of the dry discharge, the controller increases the cooling rate stepwise.  7. The electrostatic atomizer according to claim 3, wherein, in the case of the dry discharge, the controller increases the cooling rate stepwise. 8. The electrostatic atomizer according to claim 4, wherein, in the case of the dry discharge, the controller increases the cooling rate stepwise. 9. The electrostatic atomizer according to claim 1, wherein, in the case of the dry discharge, the controller increases the cooling rate to a maximum cooling rate. 10. The electrostatic fog according to claim 3 or 4, wherein when the controller stops the cooling source for the predetermined time, the controller gradually drops the cooling rate and then stops the cooling source. Generator.