Abstract:
An electrostatically atomizing device capable of instantly giving an electrostatically atomizing effect without requiring a water tank. The electrostatically atomizing device includes an emitter electrode, an opposed electrode opposed to the emitter electrode, a water feeder configured to give water on the emitter electrode, and a high voltage source configured to apply a high voltage across said emitter electrode and said opposed electrode to electrostatically charge the water on the emitter electrode for spraying charged minute water particles from a discharge end of the emitter electrode. The water feeder is configured to condense the water on the emitter electrode from within the surrounding air, enabling to supply the water on the emitter electrode in a short time without relying upon an additional water tank. Thus, an atomization of the charged minute water particles can be obtained immediately upon use of the device.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrostatically atomizing device, and more particularly to the electrostatically atomizing device which condenses water contained in the air and electrostatically charges the condensed water so as to spray the minute water particles of a nanometer order. 
     2. Description of the Related Art 
     Japanese patent publication No. 5-345156 A discloses a prior art electrostatically atomizing device generating charged minute water particles of a nanometer order (nanometer sized mist). The device is configured to apply a high voltage across an emitter electrode supplied with the water and an opposed electrode to induce Rayleigh disintegration of the water carried on the emitter electrode, thereby atomizing the water. The charged minute water particles thus obtained contain radicals and remain over a long period of time to be diffused into a space in a large amount, thereby being allowed to react effectively with offensive odors adhered to a room wall, clothing, or curtains to deodorize the same. 
     However, because the above device relies upon a water tank containing the water which is supplied through a capillary effect to the emitter electrode, it forces the user to replenish the tank. In order to eliminate the inconvenience, it may be possible to use a heat exchanger which condenses the water by cooling the surrounding air and supplying the water condensed at the heat exchanger to the emitter electrode. However, this scheme will take at least several minutes to obtain the water (condensed water) generated at the heat exchanger and supply the condensed water to the emitter electrode, and therefore poses a problem of being not applicable to an appliance such as a hair dryer which is operated only for a short time. 
     SUMMARY OF THE INVENTION 
     In view of the above problem, the present invention has been accomplished to give a solution of providing an electrostatically atomizing device which is capable of eliminating the water tank and instantly giving an electrostatically atomizing effect. 
     The electrostatically atomizing device in accordance with the present invention includes an emitter electrode, an opposed electrode opposed to the emitter electrode, a water feeder configured to give water on the emitter electrode, and a high voltage source configured to apply a high voltage across said emitter electrode and said opposed electrode to electrostatically charge the water on the emitter electrode for spraying charged minute water particles from a discharge end of the emitter electrode. The water feeder is configured to condense the water on the emitter electrode from within the surrounding air. Thus, the water contained in the air can be condensed on the emitter electrode, which enables the water to be supplied to the emitter electrode within a short time period yet without the use of an additional water tank. Accordingly, the atomization of the charged minute water particles can be obtained instantly upon use of the device. 
     Preferably, the water feeder comprises a refrigerator which cools the emitter electrode to allow the water to condense on the emitter electrode from within the surrounding air. 
     The water feeder may be configured to have a freezing function of freezing water content of the surrounding air on the emitter electrode, and also have a melting function of melting the frozen water on the emitter electrode. 
     Further, the device of the present invention preferably includes a fan which is configured to introduce the surrounding air around the emitter electrode through an air intake path. With this arrangement, it is possible to supply the humid air constantly around the emitter electrode to keep a predetermined amount of the condensed water. Also, the resulting air flow is utilized to carry the mist of the charged minute water particles emitted from the emitter electrode and discharge the particles outwardly. 
     The refrigerator is combined with a heat radiator to define a heat exchanger which is accommodated within a housing together with the emitter electrode. In this instance, the housing may be formed with a heat exchange path which is separated from the air intake path to introduce the surrounding air to the heat radiator and to drive it out of the housing. Thus, the air introduced from the outside and heated by the heat radiator is kept free from leaking to the side of the emitter electrode and, therefore, from raising the temperature around the emitter electrode, avoiding the lowering of the water condensation efficiency at the emitter electrode. 
     Further, the emitter electrode is preferably formed with a water container which holds a volume of water so that it can store the water upon seeing an excessive condensation and to secure an atomizing amount of the water by use of the water in the container in a condition where the water is difficult to be generated. Also, it is possible to reduce a hazard that the excessive water invades into other portions to cause a short-circuit. 
     The refrigerator may be realized by a Peltier-effect thermoelectric module which is compact yet has high cooling efficiency. 
     Further, the present invention discloses the device provided with a plurality of the emitter electrodes. In this instance, the plural emitter electrodes are thermally coupled to the refrigerator to have the respective discharge ends cooled to the same temperature, and at the same time electrically coupled to the high voltage source to have the respective discharge ends receiving the same electric field strength. Thus, it is possible to give a large amount of the mist of the charged minute water particles with the use of a single refrigerator. 
     The plural emitter electrodes are preferred to be integrated into a single electrode assembly. The electrode assembly has a single stem coupled to the refrigerator, and the emitter electrodes extend from the single stem, respectively, by way of branches. The use of the electrode assembly integrating the plural emitter electrodes leads to easy fabrication. Also, it is possible to give the same cooling temperature to the discharge ends of the individual emitter electrodes by use of the emitter electrodes of the same length and the branches of the same length. In this instance, all of the emitter electrodes have their respective discharge ends spaced by an equal distance from the opposed electrode to generate a uniform amount of the mist from the plural emitter electrodes in a stable manner. 
     Also, the electrode assembly is preferably made from the same material into a unitary structure in which the emitter electrodes are symmetrically disposed around the stem. 
     Further, the electrode assembly is preferably connected to receive the high voltage from the high voltage source at a point of connection offset from the branches towards the refrigerator. Thus, it is made possible to apply the high voltage to each of the emitter electrode while keeping the cooling temperature constant at the discharge end of each emitter electrode, assuring to generate the mist in a stable manner. 
     In order to effectively cool the discharge end of the emitter electrode, the electrode assembly is preferably flitted with a heat insulation sheath which covers a portion extending from the branches to the refrigerator. 
     Further, it is equally possible to provide a plurality of the opposed electrodes in correspondence to the emitter electrode. In this instance, each of the opposed electrodes is spaced by the same distance to each associated one of the emitter electrodes so as to give the same electric field strength to the discharge end of each emitter electrode, assuring to generate a large amount of the mist in a stable manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electrostatically atomizing device in accordance with a first embodiment of the present invention; 
         FIG. 2  is a top view of the above device; 
         FIG. 3  is a sectional view taken along line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 2 ; 
         FIG. 5  is a perspective view of a modification of the above device; 
         FIG. 6  is a top view of another modification of the above device; 
         FIG. 7  is a vertical section of a further modification of the above device; 
         FIG. 8  is a perspective view of an electrostatically atomizing device in accordance with a second embodiment of the present invention with a portion being removed; 
         FIGS. 9(A) ,  9 (B), and  9 (C) are explanatory views respectively illustrate the emitter electrodes of various shapes available in the present invention; and 
         FIGS. 10(A) ,  10 (B),  10 (C) and  10 (D) are explanatory views respectively illustrate the emitter electrodes of various shapes available in the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     1st Embodiment 
     An electrostatically atomizing device in accordance with the first embodiment of the present invention is explained with reference to the attached drawings. As shown in  FIGS. 1 to 4 , the electrostatically atomizing device includes a casing  10  in which a plurality of emitter electrodes  21  are disposed. Attached to the top opening of the casing  10  is an electrode plate integrating a plurality of opposed electrodes  30  which are opposed respectively to the ends of the emitter electrodes  21  by a predetermined distance. The electrode plate is formed with a plurality of circular openings  32  each having a center axis on which the tip of each corresponding emitter electrode  21  is disposed. 
     The emitter electrode  21  is coupled to a refrigerator  40  which cools and condenses the water contained in the ambient air on the emitter electrode  21 . The emitter electrode  21  and the opposed electrode  30  are connected to a high voltage source  60 . The high voltage source is provided to apply a predetermined high voltage across the emitter electrodes  21  and the opposed electrodes  30  to give a negative voltage (for example −4.6 kV) to the emitter electrodes  21 , so as to develop a high voltage electric field between a discharge end  22  at the end of each emitter electrode  21  and the inner periphery of the circular window  32  of each opposed electrode  30 , thereby electrostatically charging the water on each emitter electrode  21  for discharging the charged minute water particles in the form of a mist from the discharge end  22 . In this connection, the Rayleigh disintegration of the water is induced at the discharge end  22  to generate the mist of charged minute water particles of a size in the order of nanometers, which is discharged outwardly through the circular windows  32  of the opposed electrodes  30 . 
     The refrigerator  40  is realized by a Peltier-effect thermoelectric module (hereinafter referred to as Peltier module) which has a cooling side coupled to the ends of the emitter electrodes  21  opposite to the discharge ends  22  so as to cool the emitter electrodes  21  to a temperature below a dew point of the water by applying a constant voltage to a thermoelectric element composing the Peltier module. The Peltier module is configured to have a plurality of thermoelectric elements connected in parallel between conductive circuit plates to cool the emitter electrodes  21  at a rate determined by a variable voltage given from a cooling controller  50 . One of the conductive circuit plates on the cooling side is coupled to the emitter electrodes  21 , while the other circuit plate on the heating side is coupled to a heat radiator  45  with heat radiating fins  46 . The Peltier module is provided with a thermister for detection of the cooling temperature of the emitter electrodes  21 , and the cooling controller  50  is configured to control the temperature of the Peltier module  40  in order to keep an electrode temperature in correspondence with the environmental temperature and humidity, i.e., the temperature such that a sufficient amount of water can be condensed on the emitter electrodes. 
     The Peltier module  40  is accommodated within the casing  10  together with the emitter electrodes  21 . The casing  10  is composed of an upper casing  11  and a lower casing  15  both made of dielectric material. The upper casing  11  surrounds the upper ends of the emitter electrodes  21 , while the lower casing  15  accommodates the Peltier module  40 . Disposed between the cooling side and the emitter electrodes  21  is a dielectric plate  44  of high thermal conductivity. The upper casing  15  has its bottom closed by the heat radiator  45 . 
     A plurality of the emitter electrodes  21  are integrated into an electrode component  20  of a unitary structure. The electrode component  20  is made of a material of good electrical conductivity and high thermal conductivity such as copper, aluminum, silver, or an alloy thereof, to have a single stem  24 , and a plurality of braches  25  extending horizontally from the upper end of the stem  24  with each of the emitter electrodes  21  upstanding from the end of each branch  25 . The stem  24  has a flange  26  coupled to the cooling side of the Peltier module  40 . The stem  24  extends through an upper wall  16  of the lower casing  15  and the bottom wall  12  of the upper casing  11 , while the branches  25  extend along the top surface of the bottom wall  12 . The bottom casing  15  and the upper casing  11  are both made of a dielectric material of good thermal insulation. In this instance, a heat insulation sheath may be provided over the stem  24  extending from the Peltier module  40  to the branches  25  in order to enhance heat insulation between the electrode component  20  and the casing  10 . 
     The lower casing  15  is provided with an electrode terminal  18  for connection of the electrode component  20  to the high voltage side of the high voltage source  60 . The electrode terminal  18  has its one end connected to the flange  26  at the lower end of the stem  24  within the lower casing  15 , and has its other end extending outwardly of the lower casing  15 . The grounded side of the high voltage source  60  is connected to a grounding terminal  33  of the opposed electrodes  30 . The lower casing  15  is provided on its side end opposite to the electrode terminal  18  with a connector  19  for electrical connection with the cooling controller  50  controlling the Peltier module. 
     The upper casing  11  is provide in the lower end of its sidewall with an air inlet  14  which introduces the ambient air around the emitter electrodes  21  so as to condensate the water contained in the introduced air on the emitter electrodes  21 , allowing the condensed water to be discharged outwardly of the casing from the ends of the emitter electrodes  21  in the form of a mist of the charged minute water particles. 
     The emitter electrodes  21  are of identical shape, and are spaced horizontally from the upper end of the stem  24  by the branches  25  of the same length, as shown in  FIG. 2 , so as to be cooled to the same temperature. The discharge end  22  of each emitter electrode  21  is disposed on a center axis of the circular window  32  of each corresponding opposed electrode  30  to have the same electrical field intensity, enabling to discharge of the mist of the charged minute water particles in an equal amount from each of the emitter electrodes  21 . 
       FIG. 5  illustrates a modification of the above embodiment in which the opposed electrode  30  used in combination with the two emitter electrodes  21  is formed with a single circular window  32 , and the discharge ends are disposed at the diametrically opposed ends of the circular window  32 . In this instance, the discharge occurs between the inner periphery of the circular window  32  and each of the discharge ends  22  to generate the mist of the charged minute water particles. 
       FIG. 6  illustrates another modification in which three emitter electrodes  21  are equiangularly spaced. Also in this instance, the emitter electrodes  21  are integrated into an electrode component of unitary structure, as in the above embodiment, and are coupled to the upper end of the stem  24  by way of the branches  25  of the same length so as to be cooled to the same temperature. The opposed electrode  30  is shaped to have three circular windows  32  each having a center axis on which each emitter electrode is disposed. 
     Although the above embodiment and the modifications disclose the device equipped with a plurality of the emitter electrodes, the present invention should not be limited thereto, and is configured to use only the single emitter electrode  21  as shown in  FIG. 7 . In this modification, the tubular casing  10  is vertically divided by a partition  13  through which the emitter electrode  21  extends. The lower end of the casing  10  is coupled to the heat radiating plate  45 , while the Peltier module  40  is accommodated between the partition  13  and the heat radiating plate  45 . The Peltier module  40  is configured to have a plurality of thermo-electric elements arranged between a pair of conductive circuit plate  41  and  42 , and to have the cooling side circuit plate  41  coupled to the flange  26  at the lower end of the emitter electrode  21  through a dielectric plate of good thermal conductivity. The flange  26  is surrounded by a heat insulation sheath  7  to reduce the heat absorption to the casing. The emitter electrode  21  is connected to the electrode terminal  18  on the lower side of the partition  13 , while the Peltier module is connected to the connector  19  projecting outwardly from the lower end of the casing  10 . Provided on the upper side of the partition  13  is a water container  28  which absorbs an excessive amount of the water generated at the emitter electrode  21  to prevent the water from leaking to the side of the electrode terminal  18  and the Peltier module  40 . 
     2nd Embodiment 
       FIG. 8  illustrates an electrostatically atomizing device in accordance with second exemplary embodiment of the present invention which is basically identical to the above embodiment except that a fan  110  is accommodated within a single housing  100  together with the casing  10 . The casing  10 , which carries the emitter electrode  21 , the opposed electrode  30 , the Peltier module  40 , and the heat radiating fins  46 , is disposed in the upper end of the housing  100 , while the fan  110  is disposed in the lower end of the housing  100 . In the present embodiment, the Peltier module is utilized as a heat exchanger defining a refrigerator at its one end, and a heat radiator at the other end. The fan  110  is provided to take in the ambient air through the air inlet  102  and discharge it outwardly through an air intake path  104  and a heat exchange path  106  formed in the housing  106 . The air intake path  104  is formed downstream of the fan  110  between the casing  10  and the housing  100  to guide the forced air flow A generated by the fan from through the air inlet  14  into the casing  10 , and discharge it outwardly through the circular window  32  of the opposed electrode  30 , during which the water content of the air is condensed on the emitter electrode  21  and the mist of the charge minute particles discharged from the emitter electrode  21  is carried on the forced air flow to be expelled outwardly. 
     While, on the other hand, the heat exchange path  106  is provided to guide a forced air flow B through passes around the heat radiating fins  46  on the downstream side of the fan  110  and to expel it outwardly through discharge port  108  in the wall of the housing  100 . Thus, the air flow contacts with the heat radiating fins  46  to improve cooling effect at the Peltier module  40 . The heat exchange path  106  is separated from the air intake path  104  to avoid the air heated by the heat radiating fins from leaking towards the emitter electrode  21 . With this result, the emitter electrode  21  is supplied with the fresh air to effectively condense the water therefrom. 
     A temperature-humidity sensor  80  is provided around the air inlet  102  for detection of the environmental temperature and humidity. The cooling controller  50  controls the voltage applied to the Peltier module  40  to cool the emitter electrode  21  to a temperature determined by the environmental temperature and humidity, i.e., to the temperature at which a sufficient amount of water is condensed on the emitter electrode  21 . Also, the cooling controller  50  is connected to a current meter  70  for monitoring a discharge current flowing between the emitter electrode  21  and the opposed electrode  30 , in order to control the Peltier module for keeping the discharge current constant. As the discharge current is proportional to the amount of the charge minute water particles discharged from the discharge end  22 , or the amount of the water condensed on the emitter electrode, it is possible to continuously discharge the mist of the charged minute water particles in a constant amount by controlling the Peltier module  40  to keep the constant discharge current. 
     The fan  110  is connected to an air flow controller  120  for regulating the amount of the air flow being supplied to the emitter electrode  21  and the heat radiating fins  46 . The air flow controller  120  is connected to the current meter  70  and the temperature-humidity sensor  80  to regulate the amount of the air flow depending upon the discharge current and the environmental temperature and humidity. For example, when there is a great difference between the environmental temperature and the emitter electrode, the amount of the air flow is increased in order to enhance the cooling efficiency at the Peltier module. Also, when there is a shortage of the condensed amount of the water on the emitter electrode, the amount of air flow is increased to supply a more amount of the ambient air to the emitter electrode. On the other hand, when a sufficient amount of water is being condensed on the emitter electrode, the fan is stopped or the amount of the air flow is lowered to keep discharging the mist of the charged minute water particles in a constant amount. 
     A freezing of the water condensed on the emitter electrode  21  may occur when the emitter electrode  21  is over-cooled in a particular environment. Upon occurrence of the freezing, the discharge current is reduced and this condition can be acknowledged by the cooling controller  50 . In such case, the cooling controller  50  controls the Peltier module  40  to raise the temperature of the emitter electrode  21  to remove the freezing. For example, the cooling by the Peltier module is lowered or stopped. Further, the polarity of the voltage applied to the Peltier module may be temporarily reversed to heat the emitter electrode  21 . Under this circumstance, the cooling controller  50  can be configured to switch the functions of freezing the water content in the air and melding the frozen water in order to supply a suitable amount of water to the emitter electrode  21 . 
     As shown in  FIG. 9 , the emitter electrode  21  may be formed with a water container temporarily holding an excessive amount of water.  FIG. 9(A)  illustrates an example in which the emitter electrode  21  is formed in its center with the water container  90 A made of a porous ceramic to exhibit a capillary action. In  FIG. 9(B) , an example is illustrated in which the emitter electrode  21  is formed in its outer surface with capillary grooves extending in the axial direction to define the water container  90 B. In either example, the water container is hydrophilically treated, while the other portion is hydrophobically finished, for example, by coating with a water-repellant layer. In  FIG. 9(C) , the emitter electrode  21  is formed internally with a capillary gap extending in the axial direction to define the water container  90 C. For example, the gap may be formed in the interior of the emitter electrode by dividing the emitter electrode into two-halves or three-pieces. 
       FIG. 10  illustrates various structures of giving increased water holding capacity to the discharge end  22  of at the distal end of the emitter electrode  21 .  FIG. 10(A)  illustrates an example in which the discharge end  22  is formed with a flat face to hold the water thereon by the surface tension of the water.  FIG. 10(B)  illustrates an example in which a sharp projection is formed centrally on the flat face to concentrate the electric charge thereto. In  FIG. 10(C) , an example is illustrated in which the discharge end is formed with a concave to hold the water therein. In  FIG. 10(D) , an example is illustrated in which a sharp projection is formed centrally on the concave. In either example, the water supplied to the discharge end can be suitable held thereat, enabling the water to successfully induce the Rayleigh disintegration of the water and therefore assuring to give the electrostatic atomization in a stably matter. More than one projection may be formed to increase the amount of the mist.