Patent Publication Number: US-2022239072-A1

Title: Ionic wind generator and electronic device having heat dissipation function using same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of prior U.S. patent application Ser. No. 16/941,967 filed Jul. 29, 2020, which claims priority under 35 U.S.C. § 119 to Korean Application No. 10-2019-0116511, filed on Sep. 23, 2019, whose entire disclosures are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure generally relates to an ionic wind generator and an electronic device having a heat dissipation function using the same. More particularly, the present disclosure relates to an electronic device having a heat dissipation function capable of decreasing the temperature of a heating element by using an ionic wind. 
     Description of the Related Art 
     In recent years, with the trend of miniaturization of electronic equipment, the integration density of an electronic device is increasing, and accordingly, heat generated from the electronic equipment is increased. When the heat is not sufficiently dissipated to the outside, the performance and lifespan of the electronic equipment may be lowered and the deformation caused by the heat may cause the breakdown of the electronic equipment. 
     In particular, in recent years, communication equipment is installed in various products such as home appliances or automobiles. Such communication equipment generates a large amount of heat, so cooling functions have become important factors for product life and performance. 
     However, due to product miniaturization, it is difficult to install a high-performance cooling means such as a heat dissipation fan inside an electronic device. To solve this problem, a heat dissipation means using an ionic wind has recently been developed. The ionic wind is generated after ionizing air by applying a high voltage to an emitter electrode such as a probe or a thin wire to cause a corona discharge. When the ionic wind is moved by a strong electric field, the ambient air moves together with the ionic wind. As for the cooling technology using the ionic wind, an ionic wind generator is installed to be adjacent to a heat sink. Accordingly, technologies for cooling the heat sink using the ionic wind are disclosed. 
     In an ionic wind generator, a wire-type electrode or a needle-type electrode is used as an ionization electrode (the emitter electrode) that causes a corona discharge. Since a high voltage is applied to the ionization electrode, a wire-type electrode has a risk of breakage during use, and a needle-type electrode is prone to deterioration due to abrasion of a tip thereof during use. 
     In addition, the ionic wind generator has a low wind speed compared to a heat dissipation fan, so it is difficult to perform sufficient cooling function. However, the wind speed can be increased by making a distance between the ionization electrode and a counter electrode close. However, narrowing the distance between the ionization electrode and the counter electrode also increases the amount of ozone generated, adversely affecting the surrounding environment. Of course, in order to prevent such adverse effects by ozone, it is possible to lower the applied voltage or install a separate filter, but this method has a disadvantage of lowering the wind speed or increasing the number of parts. 
     Documents of Related Art 
     (Patent Document 1) Korean Patent No. 10-1512936 
     (Patent Document 2) Korean Patent No. 10-1513402 
     SUMMARY OF THE INVENTION 
     Accordingly, the present disclosure has been made keeping in mind the above problems occurring in the related art, and an objective of the present disclosure is intended to increase the life of an emitter electrode and the speed of an ionic wind by using a carbon brush as the emitter electrode (an ionization electrode). 
     Another objective of the present disclosure is to increase the speed and volume of the ionic wind via the carbon brush and to obtain sufficient cooling performance without using a heat sink, thereby miniaturizing an ionic wind generator. 
     Still another objective of the present disclosure is to increase the speed and volume of the ionic wind, but to reduce the amount of ozone generated as a by-product during generation of the ionic wind. 
     In order to achieve the above object, according to one aspect of the present disclosure, there is provided an ionic wind generator including: a power module; a first electrode configured to receive power from the power module by being connected to the power module to become an emitter electrode; and a second electrode spaced apart from the first electrode and grounded at the same time of being connected to the power module to become a counter electrode. The first electrode is configured as a carbon brush including multiple carbon fibers. Accordingly, in the ionic wind generator of the present disclosure, the emitter electrode is configured as the carbon brush having multiple carbon fibers, thereby providing a larger ionization amount than the wire electrode or the needle electrode, and a faster ionic wind speed than the wire electrode or the needle electrode when the carbon brush and the wire electrode or the needle electrode have the same diameters. 
     A first end of the first electrode may face the second electrode such that a distance between the first electrode and the second electrode is the shortest. When the carbon brush which is the first electrode is provided at a position close to the second electrode which is the ground electrode, a sufficiently high ionic wind speed may be obtained, so a sufficient cooling performance may be obtained even without using a heat sink, and the miniaturization of the ionic wind generator may be realized. 
     The first electrode may be mounted to a mounting arm part provided at the entrance of a module housing, wherein when the first electrode is mounted to the mounting arm part, a first end of the first electrode may face the second electrode and a second end of the first electrode positioned at an opposite side of the first end may face the outside of the installation space. In this case, the first electrode may be movably mounted to the mounting arm part, so a relative distance between the first end of the first electrode and the second electrode may be changed. Accordingly, the speed of the ionic wind may be easily adjusted according to installation environment or products to which the ionic wind generator is applied, and when the carbon brush wears out, the carbon brush may be moved outwards to restore performance thereof, which extends the life of the ionic wind generator. 
     The first electrode may be multiply provided in directions parallel to each other. The multiple first electrodes increase the volume of the ionic wind and the cooling performance of components may be improved by using the ionic wind generator. 
     In addition, when a voltage applied to the first electrode by the power module is 4 kV to 7 kV, the distance between the first electrode and the second electrode may be 3 mm to 5 mm. Such a condition may increase the speed of the ionic wind generated between the first and second electrodes. In the present disclosure, the first electrode may be configured as the carbon brush, so the amount of ozone generated may be limited compared to the existing wire electrode. 
     According to another aspect of the present disclosure, the electronic device including: the heating element provided in a casing; and the ionic wind generator provided in the casing to be adjacent to the heating element and causing an ionic wind to flow to an inner space in which the heating element is installed. In addition, the ionic wind generator includes: the first electrode configured to receive power from the power module and to be the carbon brush including multiple carbon fibers; and the second electrode spaced apart from the first electrode and grounded at the same time of being connected to the power module to become the counter electrode. Accordingly, the first electrode of the present disclosure may be configured as the carbon brush and have lower breakage and wear rates than the existing wire electrode or needle electrode, so the durability of the ionic wind generator may be improved. 
     In addition, the ionic wind generator may include: the module housing having an installation space therein; the first electrode provided at an entrance of the installation space; and the second electrode provided at an exit of the installation space, wherein the ionic wind generated by the first electrode may flow in a direction of the exit of the installation space from the entrance thereof. Accordingly, the ionic wind generator of the present disclosure may be made in a shape of a module including the first electrode and the second electrode. Accordingly, the ionic wind generator may be easily installed at the entrance of the casing. 
     In addition, the ionic wind generator may be provided to be adjacent to an inlet open at one side of the casing, and an outlet may be open at a position corresponding to an opposite side of the inlet relative to the heating element in the casing. That is, to improve cooling performance, only the inlet and outlet may be required to be made in the casing. Accordingly, the present disclosure may be applied without significantly changing a conventional electronics design. 
     Furthermore, a heat dissipation window may be open at least one side of an upper part and a lower part of the casing, wherein the heat sink of a flat plate shape may be installed in the heat dissipation window to be parallel to the circuit board. Such a heat sink may further increase the cooling performance. 
     The ionic wind generator and the electronic device having a heat dissipation function using the same of the present disclosure described above have the following effects. 
     In the ionic wind generator of the present disclosure, the emitter electrode is configured as the carbon brush having multiple carbon fibers, thereby providing a larger ionization amount than the wire electrode or the needle electrode, and a faster ionic wind speed than the wire electrode or the needle electrode when the carbon brush and the wire electrode or the needle electrode have the same diameters. Accordingly, the cooling performance of components is significantly improved by using the ionic wind generator. 
     Particularly, the carbon brush also improves the durability of the ionic wind generator since the breakage rate and wear rate of the carbon brush are lower than the breakage rate and wear rate of the existing wire electrode or needle electrode. 
     In addition, when the carbon brush which is the first electrode is provided at a position close to the second electrode which is the ground electrode, a sufficiently high ionic wind speed can be obtained, so a sufficient cooling performance can be obtained even without using a heat sink, and the miniaturization of the ionic wind generator is realized. Accordingly, the cooling performance can be enhanced inside the electronic device which has high thermal resistance but is very narrow and thus the heat dissipation design is very difficult, or even in an environment of poor heat dissipation effect since the heating element is required to be covered by a shield can. 
     Of course, when a relative distance between the first electrode and the second electrode is short, an ozone generation amount increases. However, the first electrode of the present disclosure is configured as the carbon brush, so the ozone generation amount is significantly reduced compared to the existing wire electrode. Accordingly, the present disclosure enables the implementation of the environmentally friendly ionic wind generator. 
     In addition, in the present disclosure, the relative distance between the first electrode and the second electrode is controlled by moving the carbon brush, which is the first electrode. Accordingly, the speed of the ionic wind can be easily adjusted according to installation environment or products to which the ionic wind generator is applied, and when the carbon brush wears, the carbon brush is moved outwards to restore performance thereof, which greatly extends the life of the ionic wind generator. 
     In addition, the ionic wind generator of the present disclosure is made in the shape of a module including the first electrode and the second electrode. Accordingly, the ionic wind generator can be easily installed at the entrance of the casing. Further, improvement in the cooling performance may be realized by adding only the inlet and outlet to the casing. Therefore, the present disclosure can be applied without significantly changing a conventional electronic device design, thereby having a high degree of compatibility and design freedom. 
     Furthermore, in the present disclosure, the ionic wind generated by the first electrode (the carbon brush) and the second electrode (the counter electrode) cools the heating element, resulting in no noise and vibration compared to generation of an ionic wind by using a motorized cooling fan. Accordingly, the present disclosure can be applied to various electronic devices requiring low noise/vibration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view illustrating an embodiment of an electronic device having a heat dissipation function according to the present disclosure; 
         FIG. 2  is a sectional view taken along line II-II′ of  FIG. 1 ; 
         FIG. 3  is a conceptual diagram illustrating circuit configuration for generating an ionic wind by an ionic wind generator according to the embodiment illustrated in  FIG. 1 ; 
         FIG. 4  is an exploded perspective view of components according to the embodiment illustrated in  FIG. 1 ; 
         FIG. 5  is an exploded perspective view of the components seen from a different angle according to the embodiment illustrated in  FIG. 1 ; 
         FIG. 6  is a perspective view illustrating configurations of the ionic wind generator and a circuit board according to the embodiment illustrated in  FIG. 1 ; 
         FIG. 7  is a perspective view illustrating a first embodiment of the ionic wind generator according to the present disclosure; 
         FIG. 8  is a side sectional view of configuration of the first embodiment illustrated in  FIG. 7 ; 
         FIG. 9  is a perspective view illustrating a second embodiment of the ionic wind generator according to the present disclosure; 
         FIG. 10  is a side sectional view illustrating a third embodiment of the ionic wind generator according to the present disclosure; 
         FIG. 11  is a perspective view illustrating a fourth embodiment of the ionic wind generator according to the present disclosure; and 
         FIGS. 12A and 12B  are graphs illustrating wind speeds and ozone generation amounts, respectively, according to a relative distance between a first electrode and a second electrode constituting the embodiments of the present disclosure and voltages applied thereto. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinbelow, some embodiments of present disclosure will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present disclosure, detailed descriptions of related known configurations or functions are omitted when it is determined that the understanding of the embodiments of the present disclosure is disturbed. 
     In addition, in describing the components of the embodiments of the present disclosure, terms such as first, second, A, B, a, and b may be used. These terms are only to distinguish the components from other components, and the nature or order, etc. of the components is not limited by the terms. When a component is described as being “connected”, “coupled”, or “joined” to other components, that component may be directly connected or joined to the other components, and it will be understood that other components between each component may be “connected”, “coupled”, or “joined” to each other. 
     The present disclosure relates to an ionic wind generator and an electronic device having a heat dissipation function using the same. The present disclosure may be applied to a structure poor in heat dissipation because of being installed in narrow space although having a heating element  45  generating much heat such that the structure implements high heat dissipation performance. To this end, the electronic device of the present disclosure generates an ionic wind by using the ionic wind generator  50 , and has the structure of increasing the speed of the ionic wind and the life of the ionic wind generator. 
     Here, the ionic wind uses movements of ions occurring during corona discharge. The ions generated by the discharge electrode are moved from an emitter electrode (a discharge electrode) to a collector electrode (a ground electrode) by an electric field between the electrodes, that is, by coulomb force. The ions moving in this manner move air molecules in the same direction via the collision with the air molecules, and the movements of the air molecules are joined together and are finally used as a blowing force. 
     Hereinbelow, the specific structure of the present disclosure will be described by focusing on the ionic wind generator  50  generating the ionic wind and the electronic device including the ionic wind generator  50 . 
       FIG. 1  is a perspective view illustrating an embodiment of the electronic device having a heat dissipation function according to the present disclosure, and  FIG. 2  illustrates a sectional view taken along line II-II′ of  FIG. 1 .  FIGS. 1 and 2  illustrate the entire structure of the electronic device performing a heat dissipation function, in which the ionic wind generator  50  is provided according to the present disclosure. 
     As illustrated in  FIGS. 1 and 2 , a casing  10  constitutes an outer surface and framework of the electronic device. The casing  10  may be made of a metal or nonmetallic material, and has an empty inner space therein. A circuit board  40  and the ionic wind generator  50 , which will be described hereinbelow, are provided in the inner space. In the embodiment, the casing  10  has a closed shape, but may have an open shape in a portion thereof. 
     The casing  10  includes a lower casing  30  and an upper casing  20 . When the lower casing  30  is assembled with the upper casing  20 , the inner space is defined therebetween. In the embodiment, each of the lower casing  30  and the upper casing  20  has a roughly rectangular shape, but the shape thereof may be changed variously. The casing  10  is made to be thin with a height of a size smaller than a size of a left to right width, so the height of the inner space is also low. Accordingly, the inner space of the casing  10  is in a condition in which temperature therein is easily increased when heat generated by the heating element  45  is not dissipated. 
     Referring to  FIG. 4 , a heat dissipation window  22  is open in an upper surface  21  of the upper casing  20 . The heat dissipation window  22  is a part communicating an inner space of the upper casing with the outside by opening a portion of the upper casing  20  and has an approximately rectangular shape in the embodiment. A first heat sink  29 , which will be described hereinbelow, is combined with the heat dissipation window  22  and shields the inner space. A reference numeral  28  refers to brackets, and each of the brackets protrudes from an edge of the heat dissipation window  22  such that the first heat sink  29  is assembled with the heat dissipation window  22 . 
     An upper inlet  25  is provided in the upper casing  20 . The upper inlet  25  is provided in a side surface of the upper casing  20  and is a part open to communicate the inner space of the upper casing with the outside. The upper inlet  25  may be made in various forms. In the embodiment, the upper inlet  25  is a kind of louver made in a shape of multiple slits. The upper inlet  25  defines one inlet A in cooperation with a lower inlet  35  of the lower casing  30 , which will be described below. 
     Referring to  FIGS. 2 and 5 , an upper outlet  26  is provided in the upper casing  20 . Like the upper inlet  25 , the upper outlet  26  is made on a side surface of the upper casing  20  and is a part open to communicate the inner space of the upper casing with the outside. Like the upper inlet  25 , the upper outlet  26  may be shaped like a louver. The upper outlet  26  is made on the opposite side of the upper inlet  25  and is a passage allowing the introduced air to flow to the outside. The upper outlet  26  defines one outlet B in cooperation with a lower outlet  36  of the lower casing  30 , which will be described hereinbelow. 
     The first heat sink  29  is assembled with the upper casing  20 . The first heat sink  29  is assembled at the heat dissipation window  22  of the upper casing  20  and functions to transfer heat of the inner space to the outside. To this end, the first heat sink  29  is made of a highly thermally conductive metal. The first heat sink  29  is heated due to heat generated by the circuit board  40  positioned thereunder and the heating element  45  mounted to the circuit board  40 , but an upper surface of the first heat sink is exposed to the outside, so the heat dissipation function can be performed. 
     Fastening holes  29 ′ are provided on edges of the first heat sink  29  to be assembled with the brackets  28  of the upper casing  20 , and first step parts  29   a  are provided on edges of side surfaces of the first heat sink  29 . The first step parts  29   a  are parts that are held in the edges of the heat dissipation window  22  and are continuously made by surrounding the edges of the first heat sink  29 , but may be omitted. 
     The lower casing  30  facing the upper casing  20  is assembled with the upper casing  20 . The lower casing  30  is assembled with the upper casing  20  to define one casing  10  and an inner space therein. The lower casing  30  corresponds to the upper casing  20  and has an approximately rectangular shape. Referring to the structure of the lower casing  30 , an open heat dissipation window  32  is provided in a center of the lower casing  30  as in the upper casing  20 . A second heat sink  39 , which will be described hereinbelow, is assembled with the heat dissipation window  32 . A reference numeral  38  refers to the brackets, and each of the brackets protrudes from an edge of the heat dissipation window  32  such that the second heat sink  39  is assembled with the heat dissipation window  32 . 
     Referring to  FIGS. 4 and 5 , the lower casing  30  includes part assembly holes  33 . Each of the part assembly holes  33  is an open part of a portion of a side surface of the lower casing  30 , and a connector (not shown) may be exposed through the part assembly hole  33  and be assembled with an external component. The part assembly hole  33  may be provided multiply by surrounding the lower casing  30 , and the shape, number, location thereof may be modified. 
     The lower casing  30  includes a mounting plate  34 . The mounting plate  34  protrudes from the side surface of the lower casing  30  and allows the casing  10  to be fixed to a specific position. To this end, mounting holes  34 ′ are provided in the mounting plate  34 , and a fastener passes through each of the mounting holes  34 ′ to secure the casing  10 . The mounting plate  34  is provided in a pair on opposite sides of the lower casing  30 . 
     The lower inlet  35  is provided in the lower casing  30 . The lower inlet  35  is provided in a side surface of the lower casing  30  and is a part open to communicate the inner space of the lower casing with the outside. The lower inlet  35  may be made in various forms. In the embodiment, the lower inlet  35  is a kind of louver made in a shape of multiple slits. The lower inlet  35  defines the inlet A in cooperation with the upper inlet  25  of the upper casing  20  described above. 
     Referring to  FIGS. 2 and 4 , the lower outlet  36  is provided in the lower casing  30 . Like the lower inlet  35 , the lower outlet  36  is made on a side surface of the lower casing  30  and is a part open to communicate the inner space of the lower casing with the outside. The lower outlet  36  may be shaped like a louver like the lower inlet  35 . The lower outlet  36  is made on the opposite side of the lower inlet  35 , and is a passage allowing the introduced air to let out. The lower outlet  36  defines one outlet B in cooperation with the upper outlet  26  of the upper casing  20  described above. 
     Mounting bosses  37  protrude from the lower casing  30 . Each of the mounting bosses  37  protrudes from a bottom surface of the lower casing  30  in a direction of the upper casing  20 , and includes a second assembly hole H 2  at a center thereof. The second assembly hole H 2  corresponds to a first assembly hole H 1  of the upper casing  20 , and when a bolt-like fastener is fastened to the first assembly hole H 1  and the second assembly hole H 2  to pass therethrough with the upper casing  20  and the lower casing  30  assembled tentatively, the upper casing  20  and the lower casing  30  are completely assembled. Of course, alternatively, the assembly of the upper casing  20  and the lower casing  30  may be performed in various ways, such as by a forcible fitting manner or by using adhesive. 
     The second heat sink  39  is assembled with the lower casing  30 . The second heat sink  39  is assembled with the heat dissipation window  32  of the lower casing  30  and functions to transfer heat of the inner space to the outside. To this end, the second heat sink  39  is made of a highly thermally conductive metal. The second heat sink  39  is heated due to heat generated by the circuit board  40  positioned at an upper side thereof and the heating element  45  mounted to the circuit board  40 , but a lower surface of the second heat sink is exposed to the outside, so the heat dissipation function can be performed. 
     Fastening holes  39 ′ are provided on edges of the second heat sink  39  to be assembled with the brackets  38  of the lower casing  30 , and second step parts  39   a  are provided on edges of side surfaces of the second heat sink  39 . The second step parts  39   a  are parts that are held in the edges of the heat dissipation window  32  and are made continuously by surrounding the edges of the second heat sink  39 , but may be omitted. 
     In the embodiment, the first heat sink  29  and the second heat sink  39  are installed at an upper part and a lower part of the casing  10  respectively, but only any one of the first and second heat sinks may be installed, or all thereof may be omitted. 
     The circuit board  40  is provided in the inner space S of the casing  10 . Various components may be mounted to the circuit board  40 , and when the electronic device is a communication module, other components including antennas may be added therein or connected thereto. The heating element  45  is mounted to an upper surface  41  or a lower surface  42  of the circuit board  40 , and although not shown, a shield may be provided to cover the heating element  45 . Referring to  FIGS. 2 and 5 , the heating element  45  is mounted to the circuit board  40  and protrudes therefrom. The shield, which is not shown, may block electromagnetic waves as a shield can. 
     Here, the heating element  45  may be regarded to include the circuit board  40 . Since the circuit board  40  itself may generate heat during the use of an electronic device, the circuit board  40  may also be a part of the heating element  45 . Of course, only various electrical parts mounted to the circuit board  40  may be regarded as the heating element  45 , and all of the circuit board  40  and the electrical parts may be regarded as the heating element  45 . In the embodiment, the heating element  45  is mounted only to the lower surface  42  of the circuit board  40  but alternatively, may be mounted even to the upper surface  41 . 
     The ionic wind generator  50  is installed at one side of the circuit board  40 . The ionic wind generator  50  is mounted to the casing  10  or the circuit board  40  to be adjacent to the heating element  45  and functions to cause the ionic wind to flow to an inner space in which the heating element  45  is installed. The ionic wind generator  50  is mounted in the inlet A of the casing  10  and causes the ionic wind to flow to the inner space, and the ionic wind flows up to the circuit board  40 . In the process, the heating element  45  can be cooled. 
     As described again hereinbelow, the ionic wind generator  50  includes a power module  80 , a first electrode  70 , and a second electrode  75 . The first electrode  70  is configured to receive power from the power module  80  by being connected to the power module  80  and to become the emitter electrode, and the second electrode  75  is spaced apart from the first electrode  70  in a direction closer to the heating element  45  and is grounded at the same time of being connected to the power module  80  to become the collector electrode. 
       FIG. 3  illustrates a circuit configuration for generating the ionic wind. As illustrated in  FIG. 3 , the power module  80  generates a high voltage direct current and functions to receive external power and supply the power to the first electrode  70 . In the embodiment, the power module  80  is installed at a side of the circuit board  40  and generates the voltage of 5 kv or more, and the magnitude of the voltage may change. For reference, in  FIG. 3 , a module housing  60  constituting the ionic wind generator  50  is indicated with a dotted line. 
     The first electrode  70  and the second electrode  75  are connected to the power module  80 . In the embodiment, the first electrode  70  is connected to a positive electrode (+) of the power module  80 , and the second electrode  75  is connected to a negative electrode (−) thereof. Furthermore, the second electrode  75  is grounded through the circuit board  40 . Here, the two electrodes may be reversed and the first electrode  70  may be the negative electrode. However, when the first electrode  70  is the negative electrode, ozone generation concentration by corona discharge increases and efficiency is low. Accordingly, the first electrode is preferably the positive electrode. In this case, a connection wire  85  is provided between the power module  80  and the first electrode  70 , and the power module  80  may be electrically connected to the first electrode  70 . An end  85 ′ of the connection wire  85  (see  FIG. 7 ) is combined with and electrically connected to a second end  70   a  of the first electrode  70 . In the present disclosure, the first electrode  70  is configured as a carbon brush, and such a configuration will be described again below. 
     In this connected state, when a high voltage direct current is applied to the first electrode  70  by the power module  80 , the first electrode  70  becomes the emitter electrode and the second electrode  75  becomes the collector electrode, so that the ionic wind is generated. More particularly, ions generated in the first electrode  70  by corona discharge are moved from the emitter electrode (the first electrode  70 ) to the ground electrode (the second electrode  75 ) by an electric field between the electrodes, that is, by coulomb force. The ions moving in this manner move air molecules in the same direction via the collision with the air molecules, and the movements of the moving air molecules are joined together and finally generate a blowing force. 
     Accordingly, in the present disclosure, the first electrode  70 , the second electrode  75 , and the power module  80  constitute the ionic wind generator  50 , wherein the ionic wind generator  50  generates the ionic wind and functions to cool the heating element  45  positioned in the second electrode  75 . Accordingly, the ionic wind generator  50  of the present disclosure is installed at a side of the casing  10  and is implemented when the power module  80  is mounted to the circuit board  40 , so the ionic wind generator can be applied to a conventional electronic device without significantly changing the design of the conventional electronic device. 
     In  FIGS. 6 to 8 , the configuration of the ionic wind generator  50  is illustrated in detail. Referring to  FIG. 7 , the ionic wind generator  50  includes the module housing  60  mounted to the casing  10  or the circuit board  40 . The module housing  60  constitutes the framework of the ionic wind generator  50  and is a kind of housing of an approximately hexagonal shape in the embodiment. The module housing  60  includes a housing body  61  of an insulating material such as synthetic resin. The module housing  60  has an installation space  62  having open opposite sides provided in a middle thereof, wherein the first electrode  70  is installed at an entrance of the installation space  62  and the second electrode  75  is installed at an exit of the installation space  62 . 
     The installation space  62  has an approximately rectangular shape, and the entrance of the installation space faces the outside of the casing  10 , and the exit thereof faces the inner space, that is, the heating element  45 . The installation space  62  provides a space in which the first electrode  70  and the second electrode  75  can be installed, and further secures a separation distance of the first electrode  70  and the second electrode  75  from each other. More particularly, a width direction of the installation space  62 , that is, the distance from the entrance to the exit allows the first electrode  70  and the second electrode  75  to be spaced apart from each other. 
     The first electrode  70  is installed in the installation space  62  of the module housing  60 . As illustrated in  FIG. 7 , the first electrode  70  is installed at the entrance of the installation space  62  in forward and rearward directions, and a first end  70   b  of the first electrode protrudes to the exit of the module housing  60 , that is, in a direction of the second electrode  75 . In addition, a second end  70   a  protruding to an opposite side of the first end  70   b  may be electrically connected to the power module  80  by the connection wire  85 . In the embodiment, the first electrode  70  is installed in a direction of the shortest distance toward the second electrode  75  in the installation space  62  but may be installed in an inclining direction toward the second electrode, or two or more first electrodes may be provided. 
     The first electrode  70  is configured as the carbon brush. More particularly, the first electrode  70  is configured to receive power from the power module  80  by being connected to the power module  80  to become the emitter electrode and to be the carbon brush including multiple carbon fibers. Accordingly, the carbon brush composed of multiple carbon fibers can obtain a larger ionization amount than a wire electrode or the needle electrode, and can obtain a faster ionic wind speed than a wire electrode or the needle electrode when the carbon brush and the wire electrode or the needle electrode have the same diameters. Particularly, the carbon brush has lower breakage and wear rates than the existing wire electrode or needle electrode, so the durability of the ionic wind generator  50  is improved. 
     Generally, when the emitter electrode and the collector electrode are positioned to be close to each other, wind speed becomes faster but an ozone generation amount is increased. However, the first electrode  70  of the present disclosure is configured as the carbon brush, which allows the ozone generation amount to be significantly decreased compared to the existing wire electrode. For reference, in the same condition of a diameter, a distance between electrodes, and an applied voltage, the emitter electrode of the wire electrode generates  1 . 5  times more ozone than the emitter electrode of the carbon brush. 
       FIGS. 12A and 12B  are graphs illustrating wind speeds and ozone generation amounts, respectively, according to a relative distance between the first electrode  70  and the second electrode  75  constituting the embodiments of the present disclosure and voltages applied thereto. Referring to  FIG. 12A , as the applied voltage is increased, the wind speed is increased. Results measured when relative distances L 1  (see  FIG. 8 ) between the first electrode  70  and the second electrode  75  are 3 mm, 5 mm, 7 mm, and 10 mm are illustrated as a graph. Accordingly, as the applied voltage increases, the wind speed also tends to increase. However, when the relative distance L 1  between the first electrode  70  and the second electrode  75  is 5 mm or less, the increase is relatively larger. 
     Meanwhile,  FIG. 12B  illustrates the ozone generation amount according to the relative distance L 1  between the first electrode  70  and the second electrode  75 . When the relative distance L 1  between the first electrode  70  and the second electrode  75  is 4 mm or less, the ozone generation amount exceeds a predetermined reference value of 30 PPB. Accordingly, considering both the speed of the ionic wind and the ozone generation amount, the relative distance L 1  between the first electrode  70  and the second electrode  75  is preferably 3 mm to 5 mm. 
     In addition, in the embodiment, the first electrode  70  has 10,000 to 15,000 carbon fibers, the diameter of the first electrode  70  being 1.5 mm to 3.5 mm. This is because the speed of the ionic wind is low when the diameter of the first electrode  70  is 1.5 mm or less, and the ozone generation amount exceeds 40 PPB for the same reason as mentioned above when the diameter of the first electrode  70  is 3.5 mm or more. 
     Referring to  FIGS. 7 and 8  again, the first electrode  70  has the structure of a thin and long shape and the first end thereof is installed to face the second electrode  75 . Furthermore, the first end  70   b  of the first electrode  70  faces the second electrode  75  such that the distance L 1  between the first electrode  70  and the second electrode  75  becomes the shortest. Accordingly, the distance L 1  between the first electrode  70  and the second electrode  75  is decreased, so a faster ionic wind speed can be obtained. 
     Accordingly, the first electrode  70  and the second electrode  75  are installed in the module housing  60 . Particularly, the first electrode  70  is installed at an entrance of the installation space  62  of the module housing  60  and the second electrode  75  is installed at the exit of the installation space  62 , so the ionic wind may flow in a direction of the exit from the entrance of the installation space  62 , and the ionic wind passing the exit faces the circuit board  40  and the heating element  45 . (see arrow {circle around ( 1 )} of  FIG. 8 ). In addition, an open outlet B is provided at a position corresponding to the opposite side of the inlet A relative to the heating element  45  in the casing  10 . Accordingly, the ionic wind is introduced to the inlet A and then discharged through the outlet B. 
     The first electrode  70  may be installed at a side inner than the entrance of the installation space  62 . Since the first electrode  70  receives power, the first electrode  70  may be installed at a position inside the installation space  62  for safety, but in the embodiment, a portion of the first electrode  70  protrudes to the outside of the installation space  62 . 
     In addition, in the embodiment, the first electrode  70  is mounted to a mounting arm part  65  provided at the entrance of the module housing  60 . Referring to  FIG. 9 , the mounting arm part  65  is made of an insulating material and is provided to cross opposite ends of the entrance of the module housing  60 . That is, each of opposite ends  65   a  and  65   b  of the mounting arm part  65  is connected to the module housing  60 . Alternatively, only any one end of the opposite ends  65   a  and  65   b  of the mounting arm part  65  may be connected to the module housing  60 . When the first electrode  70  is mounted to the mounting arm part  65 , the first end  70   b  of the first electrode  70  faces the second electrode  75 , and the second end  70   a  positioned at the opposite side of the first end faces the outer side of the installation space  62 . 
     Accordingly, the first electrode  70  may be movably mounted to the mounting arm part  65 . More particularly, the first electrode  70  is fitted into a combination part positioned at a center of the mounting arm part  65  and is movable in forward and rearward directions instead of being completely fixed thereto. Accordingly, the first electrode  70  may advance to or withdraw from the second electrode  75 , and the relative distance between the first end of the first electrode  70  and the second electrode  75  may be changed. In this case, the speed of the ionic wind may be easily adjusted according to the installation environment or products to which the ionic wind generator  50  is applied, and when the carbon brush wears out, the carbon brush may be moved outwards to restore performance thereof, which extends the life of the ionic wind generator  50 . 
     Next, when the second electrode  75  is seen, the second electrode  75  is installed to be spaced apart from the first electrode  70  to the exit of the installation space  62 , that is, to the inner space. The second electrode  75  is directly grounded through a ground wire  86  at the same time of being connected to the power module  80  or is grounded through the circuit board  40  to become the ground electrode. The second electrode  75  may be implemented in various structures. In the embodiment, the second electrode  75  has the structure of a metal mesh. Alternatively, the second electrode  75 , which is a thin metal plate, may be installed on an inner surface  63  of the installation space  62  and may be modified variously. 
     Meanwhile, the ionic wind generator  50  may be directly mounted to the casing  10  without the module housing  60 . For example, the first electrode  70  and the second electrode  75  may be mounted in the inlet A of the casing  10 , or the first electrode  70  and the second electrode  75  may be mounted in the inner space. 
     Looking at a process in which the ionic wind flows with reference to  FIG. 2 , first, when a high voltage direct current is applied to the first electrode  70  by the power module  80 , the first electrode  70  becomes the emitter electrode and the second electrode  75  becomes the collector electrode (the ground electrode), so that the ionic wind is generated. More particularly, ions generated in the first electrode  70  by corona discharge are moved from the emitter electrode (the first electrode  70 ) to the ground electrode (the second electrode  75 ) by an electric field between the electrodes, that is, by coulomb force. The ions moving in this manner move air molecules in the same direction (a direction of arrow {circle around ( 1 )} of  FIG. 2 ) via the collision with the air molecules, and the movements of the moving air molecules are joined together and finally generate a blowing force. 
     Accordingly, in the present disclosure, the first electrode  70 , the second electrode  75 , and the power module  80  constitute the ionic wind generator  50 , wherein the ionic wind generator  50  generates the ionic wind and functions to cool the heating element  45  positioned in the second electrode  75 . In the embodiment, the ionic wind generator  50  is installed to be adjacent to the heating element  45  and causes the ionic wind to flow to the inner space. For reference, the power module  80  may be regarded as a part of the ionic wind generator  50 , and may also be regarded as a part of the circuit board  40 . 
     The ionic wind uses the movements of ions during corona discharge. The ions generated by the discharge electrode are moved from the emitter electrode (the discharge electrode) to the collector electrode (the ground electrode) by an electric field between the electrodes, that is, by coulomb force. The ions moving in this manner move air molecules in the same direction via the collision with the air molecules, and the movements of the air molecules are joined together and are finally used as a blowing force. 
     Accordingly, the ionic wind generator  50  of the present disclosure can be applied to a structure installed in the narrow inner space S and being poor in heat dissipation in which the heating element  45  generating high temperature such as a communication module is provided and the heating element  45  is covered by the shield to block electromagnetic waves. 
     Meanwhile, the ionic wind exchanges heat with the heating element  45  and the circuit board  40  via convective heat transfer while passing the heating element  45  in the inner space. In this case, the upper surface  41  and the lower surface  42  of the circuit board  40  can exchange heat with the ionic wind. Accordingly, the surface area of a heating unit (the heating element and the circuit board) that exchanges heat with the ionic wind is increased and the convective heat transfer efficiency is improved. 
     The ionic wind having increased temperature after performing the heat exchanging exchanges heat even with the first heat sink  29  and the second heat sink  39 . The first heat sink  29  and the second heat sink  39  have temperature increased while exchanging heat with the ionic wind having the increased temperature, but the surfaces thereof are exposed to the outside, so the first heat sink and the second heat sink can be cooled. Accordingly, the temperature of the inner space may be dissipated through the first heat sink  29  and the second heat sink  39  to the outside. (see directions of arrows {circle around ( 2 )} and {circle around ( 2 )}′ of  FIG. 2 ) 
     In addition, the ionic wind having increased temperature after the ionic wind passing the heating element  45  exchanges heat with the heating element  45  is discharged through the outlet B of the casing  10  to the outside (see a direction of arrow {circle around ( 3 )} of  FIG. 2 ). Since such a process is performed continuously, the heating element  45  can be cooled. Accordingly, the ionic wind generator  50  of the present disclosure cools the heating element  45  of the electronic device by generating the ionic wind, wherein the two means of the ionic wind generator  50  and the heat sink simultaneously cool the heating element  45 , which increases the cooling efficiency and causes no noise and vibration compared to a cooling fan powered by a motor. 
     Particularly, in the present disclosure, the first electrode  70  is the carbon brush composed of multiple carbon fibers, so a relatively faster ionic wind speed can be obtained. Furthermore, the first electrode  70  of the present disclosure is configured as the carbon brush, so the ozone generation amount is significantly decreased compared to the existing wire electrode, which allows the distance L 1  between the first electrode  70  and the second electrode  75  to be sufficiently short. 
     Consequently, (i) the heat of the heating element  45  and the circuit board  40  exchanges heat with the ionic wind introduced into the inner space so as to remove the heat, and (ii) the ionic wind transfers the inner heat to the first heat sink  29  and the second heat sink  39  and the heat is dissipated to the outside, so the heating element  45  and the circuit board  40  can be cooled. 
     Next, other embodiments of the present disclosure will be described with reference to  FIGS. 9 to 11 . For reference, the description of the same parts as in the above-described embodiments will be omitted. First, referring to  FIG. 9 , the second electrode  75   b  may be a metal plate provided on an inner surface  63  of the installation space  62  of the module housing  60 . As illustrated in  FIG. 9 , the second electrode  75   b  is combined with an inner surface of an extension part  75   a  of the module housing  60  to have a thin plate structure. In the embodiment, the second electrode  75   b  is provided on each of upper and lower parts of the inner surface of the extension part  75   a  of the module housing  60 . Alternatively, the second electrode  75   b  may be provided on all of four inner surfaces of the extension part  75   a  of the module housing  60 . The extension part  75   a  may be regarded as a portion of the module housing  60 . However, of course, the second electrode  75   b  may be installed on the inner surface  63  of the installation space  62 , without the extension part  75   a  provided in the module housing  60 . 
     In addition, as illustrated in  FIG. 10 , the first electrode  70  may be multiply provided in directions parallel to each other. In  FIG. 10 , a total of two first electrodes  70  are installed to be spaced apart from each other in upward and downward directions and to be parallel to each other. Accordingly, the speed of the ionic wind may flow to a wide section. Of course, alternatively, three or more first electrodes  70  may be installed or multiple first electrodes  70  may be arranged in left to right directions. 
     Meanwhile, referring to  FIG. 11 , the ionic wind generator  50  may be directly mounted to the circuit board  40  without the connection wire  85  and the ground wire  86 . Accordingly, the first electrode  70  may be connected to the power module  80  by a pattern of the circuit board  40 , and the second electrode  75  may be grounded at the same time of being connected to the power module  80  by the pattern of the circuit board  40 . In this case, the mounting arm part  65  provided in the module housing  60  is made of a conductive material, and an end of the mounting arm part may be mounted to the circuit board  40 , and a portion of the second electrode  75  may also be mounted to the circuit board  40  by protruding to the outside of the module housing  60 . 
     In the above description, the present disclosure is not necessarily limited to these embodiments, although all elements constituting the embodiments according to the present disclosure are described as being combined or operating in combination. That is, within the scope of the present disclosure, all of the components may be selectively combined to operate in one or more. In addition, the terms “include”, “constitute”, or “having” described above mean that the corresponding component may be inherent unless otherwise stated. Accordingly, it should be construed that other components may be further included instead of being excluded. All terms, including technical and scientific terms, have the same meaning as commonly understood by ones of ordinary skills in the art to which the present disclosure belongs unless otherwise defined. Commonly used terms, such as those defined in a dictionary, should be construed as consistent with the contextual meaning of the related art and shall not be construed in an ideal or excessively formal sense unless explicitly defined in the present disclosure.