Patent Publication Number: US-2023151978-A1

Title: Ion generating device and air conditioner comprising the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Korean Patent Application No. 10-2021-0158029, filed on Nov. 16, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to an air conditioner, and more particularly, to an air conditioner having an ion generating device. 
     2. Description of the Related Art 
     In general, an air conditioner refers to a device that cools and heats a room through compression, condensation, expansion, and evaporation of a refrigerant. Such an air conditioner can improve room air quality by exchanging outdoor air with room air through a ventilation device. In addition, the ventilation device may increase the temperature of the air supplied to a room by using a high-temperature combustion gas of a gas furnace. 
     Such an air conditioner may include an ion generating device to remove bacteria or microorganisms living in the ventilation device. For example, the ion generating device generates negative ions or positive ions by applying a pulsed high voltage to a discharge electrode. An electric field formed by a high voltage applied to the discharge electrode accelerates free electrons in the surrounding air, and the accelerated free electrons collide with neutral molecules in the air, such as nitrogen or oxygen, to ionize the neutral molecules. The negative ions or positive ions generated by the ion generating device provide beneficial effects such as deodorization as well as sterilization. 
     KR 10-0762142 (patent date: Sep. 20, 2007) discloses an air conditioner that removes bacteria or microorganisms living in the inside of a duct through a sterilization kit. Specifically, the sterilization kit of the above air conditioner removes bacteria or microorganisms present in the air or living in the inside of the duct by spraying a sterilizing solution into the air supplied from the outside to the room. 
     However, the sterilization kit of the above air conditioner has the inconvenience of having to periodically refill the sterilizing solution. In addition, the sterilizing solution of the sterilization kit is provided to a duct, or the like by being loaded in the airflow of a blower operated for air conditioning in the room. That is, there is a problem in that the sterilization kit can be operated only while the air conditioning operation is being performed, and the propagation of bacteria or microorganisms cannot be prevented while the air conditioning operation is stopped. In other words, if the air conditioner is operated after not operating for a long time, the polluted air or material remaining in the duct is supplied to the room, which may cause discomfort to occupants and may adversely affect the room air. 
     KR 10-2009-0084429 (Publication date: Aug. 5, 2009) discloses a vehicle air conditioner for having an ion generating device. However, an ion generating device of the above vehicle air conditioner operates only while a blower for vehicle air conditioning is operating, and provides ions to the occupant. That is, similar to the above-mentioned registered patent, the above vehicle air conditioner also has a problem in that it cannot prevent the propagation of bacteria or microorganisms inside the duct in which the ion generating device is installed while the vehicle air conditioning operation is stopped. 
     SUMMARY OF THE INVENTION 
     One object of embodiments of the present disclosure is to solve the above and other problems. 
     Another object of embodiments of the present disclosure is to provide an air conditioner capable of supplying outdoor air by heating or cooling outdoor air. 
     Another object of embodiments of the present disclosure is to provide an ion generating device that can remove bacteria or microorganisms that grow in an environment inside the air conditioner, that is, in an environment where condensate water can be generated while it is repeatedly exposed to low temperature and high humidity according to changes in temperature and humidity. 
     Another object of embodiments of the present disclosure is to provide an ion generating device that can be operated continuously for a long time and is easy to maintain, manage and repair. 
     Another object of embodiments of the present disclosure is to provide an ion generating device that includes a fan and provides ions to a sterilization target space throughout. 
     Another object of embodiments of the present disclosure is to provide an ion generating device that includes a fan and can be operated while the air conditioning operation is stopped. 
     Another object of embodiments of the present disclosure is to provide an ion generating device capable of minimizing air flow resistance during an air conditioning operation. 
     Another object of embodiments of the present disclosure is to provide an ion generating device capable of maximizing the sterilization performance during a sterilization operation. 
     Another object of embodiments of the present disclosure is to provide a coupling structure and an optimal installation position between a ventilation device and an ion generating device of an air conditioner. 
     Another object of embodiments of the present disclosure is to provide various examples regarding the shape and number of an ionizer provided in an ion generating device. 
     In accordance with an aspect of the present disclosure, an air conditioner may include: a housing; a blower which causes a flow of air passing through an inner space of the housing; a heat exchanger located in the inner space of the housing; and an ion generating device which is spaced apart from the heat exchanger, and coupled to an inner side of the housing. 
     In accordance with another aspect of the present disclosure, the ion generating device may include: a hollow body; a fan which is coupled to one side of the body, and causes a flow of air passing through an inside of the body; and an ionizer which is coupled to the other side of the body, and generates ion. 
     In accordance with another aspect of the present disclosure, the ionizer may include a case hole which is formed in a portion of the ionizer facing the inside of the body, and communicates with the inside of the body. 
     In accordance with another aspect of the present disclosure, the ionizer may be located between an inner surface and an outer surface of the body. 
     In accordance with another aspect of the present disclosure, one surface of the ionizer may define a portion of a boundary of the inside of the body, and the case hole may be formed on the one surface of the ionizer. 
     In accordance with another aspect of the present disclosure, the fan may be coupled to the body, and the ionizer may be horizontally spaced apart from the fan. 
     In accordance with another aspect of the present disclosure, the body may include: a seating portion on which the fan is mounted; and a receiving portion which protrudes from one side of the seating portion to an outer side of the seating portion, and extends along the one side, wherein the receiving portion may include a slot which is formed from one surface of the receiving portion to an inner side of the receiving portion, and into which the ionizer is inserted. 
     In accordance with another aspect of the present disclosure, at least a portion of the one side of the seating portion is located between the ionizer and the inside of the body, and is cut-out. 
     In accordance with another aspect of the present disclosure, the ionizer may further include a plurality of ionizers spaced apart from each other along a circumference of the body. 
     In accordance with another aspect of the present disclosure, the case hole of each of the plurality of ionizers faces the inside of the body. 
     In accordance with another aspect of the present disclosure, the plurality of ionizers may include: a first ionizer which generates any one of negative ion and positive ion; and a second ionizer which faces the first ionizer, and generates ion having the same polarity as the first ionizer. 
     In accordance with another aspect of the present disclosure, the plurality of ionizers may include: a first ionizer comprising a first discharge electrode that generates negative ion and a second discharge electrode that generates positive ion; and a second ionizer comprising a third discharge electrode that generates negative ion and a fourth discharge electrode that generates positive ion. 
     In accordance with another aspect of the present disclosure, the third discharge electrode faces the first discharge electrode, and the fourth discharge electrode faces the second discharge electrode. 
     In accordance with another aspect of the present disclosure, the housing may include a top part that forms an upper side of the housing, and to which the ion generating device is coupled. 
     In accordance with another aspect of the present disclosure, a lower end of the ion generating device is located in an upper side of an upper end of the heat exchanger. 
     In accordance with another aspect of the present disclosure, the heat exchanger may further include: a first heat exchanger; and a second heat exchanger which is located downstream of the first heat exchanger, in a passage of air formed by the fan, wherein the ion generating device is located between the first heat exchanger and the second heat exchanger. 
     In accordance with another aspect of the present disclosure, a portion of the top part defines an upper boundary of a space formed between the first heat exchanger and the second heat exchanger, wherein the ion generating device is disposed in a center of the portion of the top part. 
     In accordance with another aspect of the present disclosure, the heat exchanger may further include a third heat exchanger located downstream of the second heat exchanger, in the passage of air formed by the fan. 
     In accordance with another aspect of the present disclosure, the ion generating device may further include: a first ion generating device located between the first heat exchanger and the second heat exchanger; and a second ion generating device located between the second heat exchanger and the third heat exchanger. 
     In accordance with another aspect of the present disclosure, the number of ionizers provided in the first ion generating device is equal to or greater than the number of ionizers provided in the second ion generating device. 
     In accordance with another aspect of the present disclosure, the one side of the body faces the inner side of the housing, and the fan is spaced apart from the inner side of the housing in one direction. 
     In accordance with another aspect of the present disclosure, the ion generating device may further include a plurality of legs which extend in the one direction, have one side coupled to the body, and have the other side coupled to the inner side of the housing. 
     In accordance with another aspect of the present disclosure, the fan is an axial-flow fan having a rotation shaft parallel to the one direction, an upstream of the fan is located between the fan and the inner side of the housing, and a downstream of the fan is located in the inside of the body. 
     In accordance with another aspect of the present disclosure, the plurality of legs are expanded in the one direction, or are compressible in the other direction opposite to the one direction. 
     In accordance with another aspect of the present disclosure, each of the plurality of legs may include: a first part which forms the one side of the leg; a second part which is located between the one side and the other side of the leg; and a third part which forms the other side of the leg, and to which the second part is fixed, wherein the first part is coupled to the second part to be movable in the one direction or the other direction. 
     In accordance with another aspect of the present disclosure, the air conditioner may further include a linear actuator which is disposed inside the first part and the second part, and linearly moves the first part. 
     In accordance with another aspect of the present disclosure, the air conditioner may further include a controller which is electrically connected to the blower and the ion generating device. 
     In accordance with another aspect of the present disclosure, the controller stops the ion generating device, compresses the leg through the linear actuator, and operates the blower, in an air conditioning mode. 
     In accordance with another aspect of the present disclosure, the controller stops the blower, expands the leg through the linear actuator, and operates the ion generating device, in a sterilization mode. 
     In accordance with another aspect of the present disclosure, one of the blower and the ion generating device is operated while the other is stopped. 
     In accordance with another aspect of the present disclosure, the air conditioner may further include an outdoor unit which is connected to the heat exchanger through a refrigerant pipe, and has a compressor for compressing the refrigerant, wherein a refrigerant flows through the heat exchanger. 
     In accordance with another aspect of the present disclosure, the ion generating device may include a hollow body; a fan which is coupled to one side of the body, and causes a flow of air passing through an inside of the body; and an ionizer which is coupled to the other side of the body, and generates ion. 
     In accordance with another aspect of the present disclosure, the ionizer may include a case hole which is formed in a portion of the ionizer facing the inside of the body, and communicates with the inside of the body. 
     In accordance with another aspect of the present disclosure, the ionizer may include: an ion generator including a substrate, a discharge electrode formed on one surface of the substrate, and a ground electrode formed on the other surface of the substrate; a voltage generator for applying a voltage to the discharge electrode; and a case which provides an internal space in which the ion generator and the voltage generator are installed, and in which the case hole is formed, and the one surface of the substrate may face the case hole. 
     In accordance with another aspect of the present disclosure, a photocatalyst may be coated on the surface of the discharge electrode. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present disclosure will be more apparent from the following detailed description in conjunction with the accompanying drawings, in which: 
         FIGS.  1  and  2    are views for explaining a configuration of an air conditioner according to an embodiment of the present disclosure; 
         FIG.  3    is a view for explaining a gas furnace of an air conditioner according to an embodiment of the present disclosure; 
         FIG.  4    is a perspective view of an ion generating device of an air conditioner according to an embodiment of the present disclosure; 
         FIGS.  5  and  6    are views for explaining an ionizer of an ion generating device according to an embodiment of the present disclosure; 
         FIGS.  7  and  8    are views for explaining an ion generating device of an ionizer according to an example of the present disclosure; 
         FIGS.  9  and  10    are views for explaining an ion generating device of an ionizer according to another example of the present disclosure; 
         FIG.  11    is a cross-sectional view of an ion generating device according to an embodiment of the present disclosure; 
         FIG.  12    is a view for explaining a fan of an ion generating device according to an embodiment of the present disclosure; 
         FIG.  13    is a view for explaining an ion generating device including a single ionizer according to an example of the present disclosure; 
         FIG.  14    is a view for explaining an ion generating device including at least two ionizers according to another example of the present disclosure; 
         FIG.  15  ( a ) to ( d )  are views for explaining various examples of an ionizer that generates positive and negative ions as a bipolar ionizer according to an example of the present disclosure; 
         FIG.  16  ( a ) to ( d )  are views for explaining various examples of an ionizer generating positive ions as a unipolar ionizer according to another example of the present disclosure; 
         FIG.  17  ( a ) to ( d )  are views for explaining various examples of an ionizer that generates negative ions as a unipolar ionizer according to still another example of the present disclosure; 
         FIGS.  18  and  19    are a control configuration diagram of an air conditioner and a flowchart of control method according to an embodiment of the present disclosure; 
         FIG.  20    is a view for explaining an ion generating device installed in a first space of an air conditioner according to an embodiment of the present disclosure; 
         FIG.  21    is a view for explaining an ion generating device installed in a second space of an air conditioner according to an embodiment of the present disclosure; 
         FIG.  22    is a graph for checking a change in the amount of ions according to a distance between a fan and a housing of the ion generating device according to an embodiment of the present disclosure; 
         FIGS.  23  to  24 B  are views for explaining an optimal position of an ion generating device according to an embodiment of the present disclosure; 
         FIGS.  25  to  27    are views for explaining an ion generating device having a stretchable leg according to an embodiment of the present disclosure,  FIG.  25    is a view for explaining an automatic stretching mechanism of the leg,  FIG.  26    is a view for explaining a state in which the leg of the ion generating device is compressed, and  FIG.  27    is a view for explaining a state in which the leg of the ion generating device is expanded; and 
         FIGS.  28  and  29    are a control configuration diagram of an air conditioner and a flowchart of control method according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, and the same or similar elements are denoted by the same reference numerals and redundant descriptions thereof will be omitted. 
     In the following description, with respect to constituent elements used in the following description, the suffixes “module” and “unit” are used or combined with each other only in consideration of ease in the preparation of the specification, and do not have or serve as different meanings. 
     In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in the present specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are provided only for a better understanding of the embodiments disclosed in the present specification and are not intended to limit the technical ideas disclosed in the present specification. Therefore, it should be understood that the accompanying drawings include all modifications, equivalents and substitutions included in the scope and sprit of the present disclosure. 
     Although the terms “first,” “second,” etc., may be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another component. 
     These terms are only used to distinguish one component from another component. When a component is referred to as being “connected to” or “coupled to” another component, it may be directly connected to or coupled to another component or intervening components may be present. In contrast, when a component is referred to as being “directly connected to” or “directly coupled to” another component, there are no intervening components present. 
     As used herein, the singular form is intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     In the following description, even if the embodiment is described with reference to specific drawings, if necessary, reference numerals not appearing in the specific drawings may be referred to, and reference numerals not appearing in the specific drawings are used when the reference numerals appear in the other figures. 
     The directions of up (U, y), down (D), left (Le, x), right (Ri), front (F, z), and rear (R) indicated in  FIG.  2    are used for convenience of explanation, and the technical concept of the present disclosure is not limited thereto. 
     Referring to  FIGS.  1  and  2   , an air conditioner  1  may include an outdoor unit  20  and a ventilation device  10 . The outdoor unit  20  may include a compressor (not shown) that compresses a refrigerant and an outdoor heat exchanger (not shown) that heat-exchanges the refrigerant with outdoor air. The outdoor unit  20  may be connected to the ventilation device  10  through a first refrigerant pipe  11   a . The refrigerant may circulate the outdoor unit  20  and the ventilation device  10  through the refrigerant pipe. 
     A housing  10 H may include a first long side LS 1  and a second long side LS 2  facing the first long side LS 1 . The first long side LS 1  and the second long side LS 2  may be collectively referred to as a long side LS 1 , LS 2 . The housing  10 H may include a first short side SS 1  adjacent to the long side LS 1 , LS 2  and a second short side SS 2  facing the first short side SS 1 . The first short side SS 1  and the second short side SS 2  may be collectively referred to as a short side SS 1 , SS 2 . 
     A direction perpendicular to the long side LS 1 , LS 2  and the short side SS 1 , SS 2  may be referred to as a first direction DR 1  or a left-right direction. A direction parallel to the short side SS 1 , SS 2  may be referred to as a second direction DR 2  or an up-down direction. A direction parallel to the long side LS 1 , LS 2  may be referred to as a third direction DR 3  or a front-rear direction. 
     The side of the first long side LS 1  may be referred to as an upper side (U, y), and the side of the second long side LS 2  may be referred to as the lower side D. The side of the first short side SS 1  may be referred to as a front (F, z), and the side of the second short side SS 2  may be referred to as a rear (R). In the first direction DR 1 , the direction toward one end of the short side SS 1 , SS 2  may be referred to as a left side (Le, x), and the direction toward the other end of the short side SS 1 , SS 2  may be referred to as a right side Ri. 
     A portion forming the first long side LS 1  of the housing  10 H may be referred to as a top part  10 T, and a portion forming the second long side LS 2  of the housing  10 H may be referred to as a bottom part  10 B. 
     The ventilation device  10  may include a refrigerant distributor  11 , a plurality of heat exchangers  12 ,  13 ,  14 ,  15 ,  19 , a blower  16 , a damper mount  17 , and an exhaust fan  18 . The refrigerant distributor  11 , the plurality of heat exchangers  12 ,  13 ,  14 ,  15 ,  19 , the blower  16 , the damper mount  17 , and the exhaust fan  18  may be installed inside the housing  10 H. 
     A supply air passage OA-SA may be formed between a first inlet port  10   i  and a first outlet port (not shown). The first inlet port  10   i  may be formed to penetrate the second short side SS 2 , and may be adjacent to the first long side LS 1 . The first outlet port may be formed to penetrate the second long side LS 2 , and may be adjacent to the first short side SS 1 . An outdoor air OA may flow into the first inlet port  10   i , and the first inlet port  10   i  may be referred to as an outdoor air inlet. A supply air SA may be supplied into the room through the first outlet port, and the first outlet port may be referred to as a supply air outlet. 
     The blower  16  may be located in the supply air passage OA-SA while being adjacent to the first outlet port. The blower  16  may cause a flow of air along the supply air passage OA-SA. The blower  16  may be referred to as an supply air fan  16  or a plug fan. Meanwhile, an supply air duct (not shown) may be connected to the second long side LS 2 , and may communicate with the first outlet port and the indoor space. For example, the air volume per minute of the blower  16  may be 3,000 to 5,000 cubic feet per minute (CFM). 
     An exhaust air passage RA-EA may be formed between a second inlet port  10   p  and a second outlet port  10   g . The second inlet port  10   p  may be formed to penetrate the second long side LS 2 , and may be spaced apart from the first outlet port. The second outlet port  10   g  may be formed to penetrate the second short side SS 2 , and may be adjacent to the second long side LS 2 . A room air or return air (RA) may flow into the second inlet port  10   p , and the second inlet port  10   p  may be referred to as a room air inlet. An exhaust air EA may be discharged to the outside through the second outlet port  10   g , and the second outlet port  10   g  may be referred to as an exhaust air outlet. 
     The exhaust fan  18  may be located in the exhaust air passage RA-EA while being adjacent to the second outlet port  10   g . The exhaust fan  18  may cause a flow of air along the exhaust air passage RA-EA. The exhaust fan  18  may be referred to as a blower or a plug fan. Meanwhile, a room air duct (not shown) may be connected to the second long side LS 2 , and may communicate with the second inlet port  10   p  and the indoor space. 
     The damper mount  17  may divide an inner space of the housing  10 H, between a recovery wheel  13  described later and the heat exchanger  14 , into a space where the supply air passage OA-SA is formed, and a space where the exhaust air passage RA-SA is formed. The damper mount  17  may be installed near the second inlet port  10   p  of the housing  10 H, and may include an inclined portion (no reference numeral) and a horizontal portion (no reference numeral). Accordingly, the supply air passage OA-SA may be located in the upper side of the damper mount  17 , and the exhaust air passage RA-SA may be located in the lower side of the damper mount  17 . 
     The damper  17   a  may be installed in the inclined portion of the damper mount  17 . When the damper  17   a  is opened, the supply air passage OA-SA and the exhaust air passage RA-SA may communicate with each other. When the damper  17   a  is closed, the supply air passage OA-SA and the exhaust air passage RA-SA may be separated from each other. For example, in the initial stage of the heating operation of the air conditioner, the blower  16  may be operated while the exhaust fan  18  may be stopped, and the damper  17   a  may be opened. 
     The refrigerant distributor  11  may be adjacent to the first long side LS 1  and the first short side SS 1 . One side of the refrigerant distributor  11  may be connected to the first refrigerant pipe  11   a . The other side of the refrigerant distributor  11  may be connected to a plurality of refrigerant pipes  11   b ,  11   c ,  11   d , and  11   e . For example, the refrigerant distributor  11  may open and close the passage of each refrigerant pipe through a solenoid valve. Here, each refrigerant pipe  11   b ,  11   c ,  11   d ,  11   e  may include a refrigerant pipe providing a passage of the refrigerant supplied to each heat exchanger  12 ,  14 ,  15 ,  19 , and a refrigerant pipe providing a passage of the refrigerant passing through each heat exchanger  12 ,  14 ,  15 ,  19 . In addition, each expansion valve (not shown) may be connected to each refrigerant pipe  11   b ,  11   c ,  11   d ,  11   e , and may expand the refrigerant flowing through each refrigerant pipe  11   b ,  11   c ,  11   d , and  11   e . For example, the expansion valve may be an electronic expansion valve (EEV) capable of adjusting the opening degree. In this case, when the expansion valve is fully opened, the expansion valve may not expand the refrigerant. 
     A radiator  12  may be located in the supply air passage OA-SA while being adjacent to the first inlet port  10   i . The high-temperature cooling water described later may pass through the radiator  12 . Accordingly, the radiator  12  may heat the air introduced into the first inlet port  10   i . The radiator  12  may be referred to as a radiant heat coil. 
     The heat exchanger  14  may be located downstream of the radiator  12  in the supply air passage OA-SA. The heat exchanger  14  may be vertically disposed inside the housing  10 H. The size of the heat exchanger  14  may be larger than the size of the radiator  12 . The second refrigerant pipe  11   c  may provide a refrigerant passage connecting the refrigerant distributor  11  and the heat exchanger  14 . The heat exchanger  14  may be referred to as a main heat exchanger or a cooling/heating coil. The heat exchanger  14  may be referred to as a second heat exchanger  14 . Meanwhile, a filter  14   a  (see  FIG.  23   ) may be located upstream of the heat exchanger  14 . 
     A reheater  15  may be located downstream of the heat exchanger  14  in the supply air passage OA-SA. The reheater  15  may be vertically disposed inside the housing  10 H. The size of the reheater  15  may be smaller than the size of the heat exchanger  14 . The third refrigerant pipe  11   d  may provide a refrigerant passage connecting the refrigerant distributor  11  and the reheater  15 . The reheater  15  may be referred to as a reheat coil. The reheater  15  may be referred to as a third heat exchanger  15 . 
     Meanwhile, the reheater  15  may be operated based on the indoor set temperature and set humidity. The reheater  15  may face the blower  16  with respect to a base  10 W on which the reheater  15  is installed. 
     A recovery coil  19  may be located in the exhaust air passage RA-EA while being adjacent to the exhaust fan  18 . The recovery coil  19  may be vertically disposed inside the housing  10 H. The fourth refrigerant pipe  11   e  may provide a refrigerant passage connecting the refrigerant distributor  11  and the recovery coil  19 . Meanwhile, the heat transfer direction of the recovery coil  19  with respect to the air may be opposite to the heat transfer direction of the heat exchanger  14  with respect to the air. 
     A recovery wheel  13  may have a flat cylinder shape as a whole. A honeycomb structure may be formed inside the recovery wheel  13 , and air may pass through the honeycomb structure. The recovery wheel  13  may be rotated by the power of a motor  13   p . A rotation shaft of the recovery wheel  13  may be a length direction shaft of the recovery wheel  13 , and the recovery wheel  13  may rotate in a circumferential direction of the recovery wheel  13 . For example, the power of the motor  13   p  may be transmitted to the recovery wheel  13  using a belt and a pulley. 
     In addition, a first portion  13   a  of the recovery wheel  13  may be located in the supply air passage OA-SA. In the supply air passage OA-SA, the first portion  13   a  may be located between the radiator  12  and the heat exchanger  14 . In addition, a second portion  13   b  of the recovery wheel  13  may be located in the exhaust air passage RA-EA. In the exhaust air passage RA-EA, the second portion  13   b  may be located between the inclined portion of the damper mount  17  and the recovery coil  19 . In this case, a portion corresponding to the first portion  13   a  or the second portion  13   b  of the recovery wheel  13  may be changed in response to the rotation of the recovery wheel  13 . The recovery wheel  13  may be referred to as a first heat exchanger  13 . 
     Accordingly, the recovery wheel  13  may recover sensible heat and latent heat by using the temperature difference and humidity difference between the outdoor air OA and the room air RA. The recovery wheel  13  may be referred to as an energy recovery wheel (ERW). 
     Referring to  FIGS.  2  and  3   , the blower  16  may include a motor  16   a , a hub  16   b , a shroud  16   c , and a plurality of blades  16   d . The hub  16   b , the shroud  16   c , and the plurality of blades  16   d  may be collectively referred to as an impeller. 
     The motor  16   a  may provide rotational force. The motor  16   a  may be a centrifugal fan motor. The motor  16   a  may form a front end of the blower  16 , and the rotational shaft of the motor  16   a  may extend rearward from the motor  16   a . The length direction of the rotation shaft of the motor  16   a  may be referred to as a shaft direction of the blower  16 . 
     The hub  16   b  may be located in the rear of the motor  16   a  and may be fixed to the rotation shaft of the motor  16   a . The hub  16   b  may have a disk shape. 
     The shroud  16   c  may be located at the rear of the hub  16   b  and may have a ring plate shape. The shroud  16   c  may be rotatably coupled to the base  10 W. For example, an inflow portion (no reference numeral) may be fixed to the front surface of the base  10 W, between the shroud  16   c  and the base  10 W, and may have a hyperbolic cylinder or funnel shape. In this case, the shroud  16   c  may be rotatably coupled to the inflow portion. The hole formed inside the shroud  16   c , the inner space of the inflow portion, and a hole (not shown) formed in the base  10 W may communicate with each other, and may be located in the supply air passage OA-SA (see  FIG.  1   ). 
     The plurality of blades  16   d  may be located between the inner periphery and the outer periphery of the ring-shaped shroud  16   c . The plurality of blades  16   d  may be coupled to the hub  16   b  and the shroud  16   c , between the hub  16   b  and the shroud  16   c . The plurality of blades  16   d  may be formed as one body with the shroud  16   c  and the hub  16   b.    
     In addition, the plurality of blades  16   d  may be spaced apart from each other in the rotational direction of the rotation shaft of the motor  16   a . Each of the plurality of blades  16   d  may be convexly curved in the rotational direction of the rotation shaft. For example, a blade located close to a mount plate  110  described later, among the plurality of blades  16   d , may be convex toward the mount plate  110 . 
     Accordingly, when the impeller  16   a ,  16   b ,  16   c  rotates clockwise according to the driving of the motor  16   a , air may be introduced in the shaft direction of the blower  16  through the hole of the base  10 W, and may be pressed by the plurality of blades  16   d  to be discharged in the radial direction of the blower  16 . 
     A horizontal plate  10   a  may be vertically disposed on the front surface of the base  10 W, and may be coupled to the front surface of the base  10 W. The horizontal plate  10   a  may be located in the upper side of the blower  16 . The horizontal plate  10   a  may be referred to as a first horizontal wall or a first panel. Meanwhile, the frame  16   e  may form a skeleton of the blower  16 , and may be coupled to a motor mount  1600  in which the motor  16   a  is mounted. The frame  16   e  may be coupled to the lower side of the horizontal plate  10   a.    
     A top plate  10   b  may be vertically disposed on the front surface of the base  10 W, and may be coupled to the front surface of the base  10 W. The top plate  10   b  may be located in the lower side of the blower  16 . The top plate  10   b  may be referred to as a second horizontal wall or a second panel. A top hole  100   a  may be formed to penetrate the top plate  10   b  in the up-down direction. The top hole  100   a  may be formed to be long in the left-right direction. In the up-down direction, at least a portion of the top hole  100   a  may overlap with the blower  16 . 
     A bottom plate  10   c  may be vertically disposed on the front surface of the base  10 W, and may be coupled to the front surface of the base  10 W. The bottom plate  10   c  may face the horizontal plate  10   a  with respect to the top plate  10   b . The bottom plate  10   c  may form a part of the second long side LS 2  of the housing  10 H. A bottom hole  100   b  may be formed to penetrate the bottom plate  10   c  in the up-down direction. The bottom hole  100   b  may be formed to be long in the left-right direction. In the up-down direction, the bottom hole  100   b  may face the top hole  100   a.    
     A side plate  10   d  may be vertically disposed on the front surface of the base  10 W, and may be coupled to the front surface of the base  10 W. The side plate  10   d  may be coupled to a right side of the horizontal plate  10   a , a right side of the top plate  10   b , and a right side of the bottom plate  10   c.    
     The mount plate  110  may include a first plate  111  and a second plate  112 . The first plate  111  may be vertically disposed on the front surface of the base  10 W and the upper surface of the bottom plate  10   c , and may be coupled to the front surface of the base  10 W and the upper surface of the bottom plate  10   c . The first plate  111  may be coupled to the left side of the top plate  10   b . The second plate  112  may extend obliquely from the upper end of the first plate  111  in a direction away from the blower  16 . In this case, the left side of the base  10 W, the left side of the horizontal plate  10   a , the left side of the second plate  112 , and the left side of the bottom plate  10   c  may be connected to the left portion of the housing  10 H. 
     A first space  101 S may be formed between the horizontal plate  10   a  and the top plate  10   b . A vertical plate (not shown) may be connected to the front end of the horizontal plate  10   a  and the front end of the top plate  10   b , and may close the front of the first space  101 S. 
     A second space  102 S may be formed between the top plate  10   b  and the bottom plate  10   c . The vertical plate may be connected to the front end of the top plate  10   b  and the front end of the bottom plate  10   c , and may close the front of the second space  102 S. The second space  102 S may communicate with the first space  101 S through the top hole  100   a , and may communicate with the indoor space through the bottom hole  100   b.    
     Referring back to  FIG.  3   , a gas furnace  100  may include a fuel valve  120 , a manifold  130 , a burner  141 , a heat exchanger  150 , a collect box  160 , and an inducer  170 . 
     The fuel valve  120  may supply fuel from a fuel pipe (not shown) to the manifold  130 , or may block the supply of the fuel to the manifold  130 . For example, the fuel may be a liquefied natural gas (LNG) or a liquefied petroleum gas (LPG). Meanwhile, the amount of the fuel supplied to the manifold  130  may be adjusted by adjusting the opening degree of the fuel valve  120 . In other words, the thermal power of the gas furnace  100  may be adjusted in stages by using the fuel valve  120 . The fuel valve  120  may be referred to as a modulating valve. 
     The burner  141  may be supplied with the fuel from the manifold  130 . For example, primary air may flow into the burner  141  through a space between the burner  141  and the manifold  130 . In this case, the fuel may pass through the burner  141  and be mixed with the primary air. The burner  141  may burn the fuel. When the fuel is burned, a flame and high-temperature combustion gas may be generated. For example, a plurality of burners  141  may be provided. The plurality of burners  141  may be installed inside a burner box  140 . The burner box  140  may be installed in the left side of the first plate  111  of the mount plate  110 . 
     For example, an igniter  140   a  may be adjacent to an exit of burner located in one end of the plurality of burners  141 , and may burn fuel that has passed through the burner. In this case, the flame formed in the exit of the burner may be propagated to the exit of the remaining burners through a flame propagation port between the plurality of burners  141 . The propagated flame may burn fuel that has passed through the remaining burners. In addition, a flame detector  140   b  may be adjacent to the exit of burner located in the other end of the plurality of burners  141 . When the flame detector  140   b  detects a flame, it can be considered that the flame according to the combustion reaction is formed in the remaining burners due to the characteristics of the flame propagation described above. 
     The heat exchanger  150  may be located in the second space  102 S between the top plate  10   b  and the bottom plate  10   c . The heat exchanger  150  may provide a passage for the combustion gas. One end of the heat exchanger  150  may be coupled to the right side of the first plate  111  of the mount plate  110 . The other end of the heat exchanger  150  may be spaced apart from the one end of the heat exchanger  150 , and may be coupled to the right side of the first plate  111 . 
     In addition, a plurality of heat exchangers  150  may be provided. The number of heat exchangers  150  may be the same as the number of burners  141 . Each of the plurality of heat exchangers  150  may be connected to each of the plurality of burners  141 . The plurality of heat exchangers  150  may be spaced apart from each other in the front-rear direction. 
     In addition, the heat exchanger  150  may be a tubular type heat exchanger. The heat exchanger  150  may include a first tube  150   a , a band  150   b , and a second tube  150   c . The passage of the combustion gas may be formed in the inside of the first tube  150   a , the inside of the band  150   b , and the inside of the second tube  150   c . For example, the diameter of the first tube  150   a  may be substantially equal to the diameter of the band  150   b  and the diameter of the second tube  150   c.    
     The first tube  150   a  may extend long in the left-right direction. The left distal end of the first tube  150   a  may form the one end of the heat exchanger  150 , and may be referred to as an entrance of the heat exchanger  150 . The entrance of the heat exchanger  150  may communicate with the burner  141  through a first hole (not shown) formed in the first plate  111 . 
     The second tube  150   c  may extend long in the left-right direction. The second tube  150   c  may be spaced upwardly from the first tube  150   a . The left distal end of the second tube  150   c  may form the other end of the heat exchanger  150 , and may be referred to as an exit of the heat exchanger  150 . The exit of the heat exchanger may communicate with the inside of the collect box  160  described later through a second hole (not shown) formed in the first plate  111 . 
     The band  150   b  may be connected to the right distal end of the first tube  150   a  and the right distal end of the second tube  150   c . The band  150   b  may be formed to be convex to the right. The band  150   b  may transmit the combustion gas passing through the first tube  150   a  to the second tube  150   c . Accordingly, the combustion gas may flow to the right in the first tube  150   a , and may flow to the left in the second tube  150   b . The band  150   b  may be referred to as a U-shaped bend. 
     The collect box  160  may be located in the upper side of the burner box  140 , and may be installed in the left side of the first plate  111  of the mount plate  110 . The combustion gas passing through the heat exchanger  150  may flow into the inside of the collect box  160 . 
     The inducer  170  may be installed in the left side of the collect box  160 . The entrance of the inducer  170  may communicate with the inside of the collect box  160 . An exit  171  of the inducer  170  may be connected to an exhaust pipe  180  (see  FIG.  2   ). The inducer  170  may cause the combustion gas to flow through the heat exchanger  150 , the collector box  160 , the inducer  170 , and the exhaust pipe  180 . In addition, the inducer  170  may cause the fluid to flow through the burner  141 . Meanwhile, the inducer  170  may be referred to as a fan. 
     The exhaust pipe  180  (see  FIG.  2   ) may extend upwardly from the exit  171  of the inducer  170 . The exhaust pipe  180  may penetrate the second plate  112  of the mount plate  110 , the horizontal plate  10   a , and the first long side LS 1 , and may discharge the combustion gas to the outside. The combustion gas flowing through the exhaust pipe  180  may be referred to as exhaust gas. For example, the temperature of the exhaust gas may be about 250 to 300° C. 
     Accordingly, the air discharged from the blower  16  may pass around the heat exchanger  150  via the top hole  100   a , and may be supplied into the room through the bottom hole  100   b . Here, the bottom hole  100   b  may be the first outlet port described above with reference to  FIGS.  1  and  2   . At this time, the air passing around the heat exchanger  150  may receive heat energy from the combustion gas flowing along the heat exchanger  150 . That is, the temperature of the air may rise while passing around the heat exchanger  150 . 
     Referring to  FIGS.  1  and  4   , an ion generating device  190  may be mounted inside the top part  10 T which is a portion forming the first long side LS 1  of the housing  10 H. The ion generating device  190  may be referred to as an ion supply device or a sterilization device. 
     The ion generating device  190  may include a bracket  191 , an ionizer  192 , and a fan  193 . The bracket  191  may be fixed to the inside of the housing  10 H, and the ionizer  192  and the fan  193  may be detachably coupled to the bracket  191 . 
     Referring to  FIG.  5   , the bracket  191  may include a base  191   a , a body  191   b , and a plurality of legs  191   c.    
     The base  191   a  may form a lower surface of the bracket  191 . The base  191   a  may have a ring shape as a whole. That is, in the up-down direction, a discharge hole  191   h  may penetrate the upper and lower surfaces of the bracket  191 . The base  191   a  may be referred to as a ring plate or a bottom plate. 
     The body  191   b  may protrude upward from the top surface of the base  191   a . The body  191   b  may have a hollow block shape as a whole. That is, the body  191   b  may be opened vertically. In the up-down direction, the discharge hole  191   h  may penetrate the upper and lower surfaces of the body  191   b . The body  191   b  may be referred to as a block. In addition, the body  191   b  may include a seating portion  191   b   1  and a receiving portion  191   b   2 . All parts of the seating portion  191   b   1  and the receiving portion  191   b   2  may be located on the base  191   a.    
     The seating portion  191   b   1  may have four sides BS 1 , BS 2 , BS 3 , and BS 4  that are orthogonal to each other. The aforementioned discharge hole  191   h  may be formed in the seating portion  191   b   1 . A diagonal length wb of the seating portion  191   b   1  may be greater than a height hb of the seating portion  191   b   1 . 
     The receiving portion  191   b   2  may protrude from the first side BS 1  of the seating portion  191   b   1  in the radial direction of the base  191   a . The receiving portion  191   b   2  may extend along the first side BS 1 , and may be formed as one body with the second side BS 2  and the fourth side BS 4  of the seating portion  191   b   1 . Here, the second side BS 2  and the fourth side BS 4  may be connected to the first side BS 1 , and may face each other with respect to the first side BS 1 . The height of the receiving portion  191   b   2  may be the same as the height hb of the seating portion  191   b   1 . 
     A slot  191 S may be formed inside the receiving portion  191   b   2  from the upper surface of the receiving portion  191   b   2 . A portion of the first side BS 1  may be cut-out, and the slot  191 S may communicate with the discharge hole  191   h  through the portion of the first side BS 1 . The shape of the slot  191 S may correspond to the shape of the ionizer  192 . 
     In this case, the ionizer  192  may be detachably inserted into the slot  191 S. That is, the ionizer  192  may be located between the inner surface and the outer surface of the body  191   b . The ionizer  192  inserted into the slot  191 S may be detachably coupled to the inside of the receiving portion  191   b   2  through a coupling portion  1921 ,  1922 . The ionizer  192  coupled to the receiving portion  191   b   2  may communicate with the discharge hole  191   h.    
     The plurality of legs  191   c  may be fixed to the upper surface of the base  191   a . The plurality of legs  191   c  may be located around the body  191   b . For example, a first leg  191   c   1  may face the first side BS 1  with respect to the receiving portion  191   b   2 . In addition, each of a second leg  191   c   2 , a third leg  191   c   3 , and a fourth leg  191   c   4  may face each of the second side BS 2 , the third side BS 3 , and the fourth side BS 4 . 
     In addition, the plurality of legs  191   c  may extend in the up-down direction. The height of the plurality of legs  191   c  may be greater than the sum of the above-described height hb of the body  191   b  and the height of the fan  193  (see  FIG.  4   ). 
     In addition, a foot  191   d  may be bent to the outside of the bracket  191  from the upper end of the leg  191   c . The foot  191   d  may be orthogonal to the leg  191   c , and may contact the inside of the top part  10 T (see  FIG.  1   ) which is a portion forming the first long side LS 1  of the housing  10 H. A fastening member such as a screw may be coupled to the inside of the housing  10 H through a hole  191   e  formed in the foot  191   d.    
     Accordingly, the bracket  191  may be detachably coupled to the inner side of the housing  10 H. In this case, the components (see  FIG.  4   ) of the ion generating device  190  excluding the foot  191   d  may be spaced apart from the inner side of the housing  10 H to the lower side. 
     Referring to  FIG.  6   , the ionizer  192  may include a case  192 R,  192 F, a voltage generator  192 P, and an ion generator  192 E. 
     The case  192 R,  192 F may be extended long. The case  192 R,  192 F may include a rear case  192 R and a front case  192 F that are detachably coupled to each other. The internal space  192 S of the case  192 R,  192 F may be formed between the rear case  192 R and the front case  192 F. The above-described coupling portions  1921 ,  1922  (see  FIG.  5   ) may be formed in a side surface of the rear case  192 R. A case hole  192   g  may be formed in the front surface of the front case  192 F and may communicate with the internal space  192 S. For example, the front surface of the case  192 F may have a grille shape. 
     The voltage generator  192 P may be installed in the internal space  192 S and may be connected to a power source (not shown). The voltage generator  192 P may include a printed circuit board PCB (no reference numeral) and a transformer  192 P 1  mounted on the PCB. The voltage generator  192 P may be electrically connected to the ion generator  192 E described later through a wire L 1 , L 2 , L 0 , and may apply a high voltage to the ion generator  192 E. The voltage generator  192 P may be referred to as a high voltage generator. 
     The ion generator  192 E may be installed in the internal space  192 S, and may be located between the voltage generator  192 P and the front case  192 F. That is, the ion generator  192 E may face the case hole  192   g . The electrodes E 1  and E 2  may be formed on the surface of the ion generator  192 E. When a high voltage is applied to the electrodes E 1  and E 2  by the voltage generator  192 P, ions may be generated, which will be described in more detail later. 
     Referring to  FIGS.  7  and  8   , the ion generator  192 E may include a substrate B, a discharge electrode E 1 , E 2 , and a ground electrode E 3 . 
     The substrate B may be formed of a dielectric substance. For example, the substrate B may include a ceramic or synthetic resin material. A first surface Bt of the substrate B may face the case hole  192   g  (see  FIG.  6   ), and a second surface Bb of the substrate B may face the voltage generator  192 P. The first surface Bt may be referred to as a front surface or an upper surface, and the second surface Bb may be referred to as a rear surface or a lower surface. 
     The discharge electrode E 1 , E 2  may be formed on the first surface Bt of the substrate B. The discharge electrode E 1 , E 2  may include a metal material such as copper Cu. For example, the discharge electrode E 1 , E 2  may include a first discharge electrode E 1  and a second discharge electrode E 2  spaced apart from each other in the length direction of the substrate B. For example, the first discharge electrode E 1  and the second discharge electrode E 2  may be symmetrical vertically. 
     The first discharge electrode E 1  may include a first point E 1   a , a first line E 1   b , a first outer circle E 1   c , and a first inner circle E 1   d.    
     The first point E 1   a  may be connected to a first wire L 1  (see  FIG.  6   ), and may be a portion to which the voltage of the voltage generator  192 P (see  FIG.  6   ) is applied. The first point E 1   a  may be referred to as a first terminal. 
     The first line E 1   b  may connect the first point E 1   a  and first circles E 1   c  and E 1   d.    
     The first outer circle E 1   c  and the first inner circle E 1   d  may be a concentric circle. A diameter of the first outer circle E 1   c  may be greater than a diameter of the first inner circle E 1   d . A portion of the aforementioned first line E 1   b  may be connected to the first outer circle E 1   c  and the first inner circle E 1   d  from between the first outer circle E 1   c  and the first inner circle E 1   d.    
     In addition, the first outer circle E 1   c  may include first outer needles E 1   cn . In addition, the first inner circle E 1   d  may include first inner needles E 1   dn . For example, the number of the first outer needles E 1   cn  may be greater than the number of the first inner needles E 1   dn . Meanwhile, a barrier E 1   e  may be located between the first outer circle E 1   c  and the first inner circle E 1   d , and may minimize discharge interference between the first outer needles E 1   cn  and the first inner needles E 1   dn.    
     The second discharge electrode E 2  may include a second point E 2   a , a second line E 2   b , a second outer circle E 2   c , and a second inner circle E 2   d.    
     The second point E 2   a  may be connected to a second wire L 2  (see  FIG.  6   ), and may be a portion to which the voltage of the voltage generator  192 P (see  FIG.  6   ) is applied. The second point E 2   a  may be referred to as a second terminal. 
     The second line E 2   b  may connect the second point E 2   a  and the second circles E 2   c  and E 2   d.    
     A second outer circle E 2   c  and a second inner circle E 2   d  may be a concentric circle. A diameter of the second outer circle E 2   c  may be greater than a diameter of the second inner circle E 2   d . A portion of the aforementioned second line E 2   b  may be connected to the second outer circle E 2   c  and the second inner circle E 2   d , from between the second outer circle E 2   c  and the second inner circle E 2   d.    
     In addition, the second outer circle E 2   c  may include second outer needles E 2   cn . In addition, the second inner circle E 2   d  may include second inner needles E 2   dn . For example, the number of the second outer needles E 2   cn  may be greater than the number of the second inner needles E 2   dn . Meanwhile, a barrier E 2   e  may be located between the second outer circle E 2   c  and the second inner circle E 2   d , and may minimize discharge interference between the second outer needle E 2   cn  and the second inner needles E 2   dn.    
     A ground electrode E 3  may be formed on the second surface Bb of the substrate B. The ground electrode E 3  may include a metal material such as copper Cu. For example, the ground electrode E 3  may include a ground point E 3   a , a connector E 3   b , a first ground electrode E 31 , and a second ground electrode E 32 . The ground point E 3   a  may be connected to a wire L 0  (see  FIG.  6   ). The connector E 3   b  may connect the ground point E 3   a  to the first and second ground electrodes E 31  and E 32 . 
     In addition, in a thickness direction of the substrate B, the first ground electrode E 31  may be aligned with the first discharge electrode E 1 . The first ground electrode E 31  may have a shape corresponding to the first outer circle Etc and the first inner circle E 1   d  of the first discharge electrode E 1 . 
     In addition, in the thickness direction of the substrate B, the second ground electrode E 32  may be aligned with the second discharge electrode E 2 . The second ground electrode E 32  may have a shape corresponding to the second outer circle E 2   c  and the second inner circle E 2   d  of the second discharge electrode E 2 . 
     Accordingly, when a high voltage is applied to the discharge electrodes E 1  and E 2  by the voltage generator  192 P, the discharge electrodes E 1  and E 2  may generate a negative ion and/or a positive ion. That is, the first discharge electrode E 1  may be a negative ion discharge electrode that generates a negative ion or a positive ion discharge electrode that generates a positive ion. In addition, the second discharge electrode E 2  may be a negative ion discharge electrode that generates a negative ion or a positive ion discharge electrode that generates a positive ion. 
     Referring to  FIGS.  9  and  10   , the ion generator  192 E may include a substrate B, a discharge electrode E 1 ′, E 2 ′, and a ground electrode E 3 ′. 
     The substrate B may be formed of a dielectric substance. For example, the substrate B may include a ceramic or synthetic resin material. The first surface Bt of the substrate B may face the case hole  192   g  (see  FIG.  6   ), and the second surface Bb of the substrate B may face the voltage generator  192 P. The first surface Bt may be referred to as a front surface or an upper surface, and the second surface Bb may be referred to as a rear surface or a lower surface. 
     The discharge electrode E 1 ′, E 2 ′ may be formed on the first surface Bt of the substrate B. The discharge electrode E 1 ′, E 2 ′ may include a metal material such as copper Cu. For example, the discharge electrode E 1 ′, E 2 ′ may include a first discharge electrode E 1 ′ and a second discharge electrode E 2 ′ spaced apart from each other in the length direction of the substrate B (see gE). For example, the first discharge electrode E 1 ′ and the second discharge electrode E 2 ′ may be symmetrical vertically. 
     The first discharge electrode E 1 ′ may include a first point E 1   a ′, a first line E 1   b ′, and a pair of first circles E 11  and E 12 . 
     The first point E 1   a ′ may be connected to the first wire L 1  (see  FIG.  6   ), and may be a portion to which a voltage of the voltage generator  192 P (see  FIG.  6   ) is applied. The first point E 1   a ′ may be referred to as a first terminal. 
     The first line E 1   b ′ may connect the first point E 1   a ′ and the pair of first circles E 11  and E 2 . 
     The pair of first circles E 11  and E 12  may be spaced apart from each other in the length direction of the substrate B. The pair of first circles E 11  and E 12  may have a shape corresponding to each other. For example, any one of the pair of first circles E 11  and E 12  may have a shape which is the shape of the other one that is rotated counterclockwise or clockwise by 90 degrees. In this case, the description of any one of the pair of first circles E 11  and E 12  may be identically applied to the other one. In addition, the first circle E 11 , which is one of the pair of first circles E 11  and E 12 , may include a first outer circle E 11   c  and a first inner circle E 11   d.    
     The first outer circle E 11   c  and the first inner circle E 11   d  may be concentric. A diameter of the first outer circle E 11   c  may be greater than a diameter of the first inner circle E 11   d . A portion of the aforementioned first line E 1   b ′ may be connected to the first outer circle E 11   c  and the first inner circle E 11   d  from between the first outer circle E 11   c  and the first inner circle E 11   d.    
     In addition, the first outer circle E 11   c  may include first outer needles E 11   cn . In addition, the first inner circle E 11   d  may include first inner needles E 11   dn . For example, the number of the first outer needles E 11   cn  may be greater than the number of the first inner needles E 11   dn . Meanwhile, a barrier (not shown) may be located between the first outer circle E 11   c  and the first inner circle E 11   d , and may minimize discharge interference between the first outer needles E 11   cn  and the first inner needles E 11   dn.    
     The second discharge electrode E 2 ′ may include a second point E 2   a ′, a second line E 2   b ′, and a pair of second circles E 21  and E 22 . 
     The second point E 2   a ′ may be connected to a second wire L 2  (see  FIG.  6   ), and may be a portion to which the voltage of the voltage generator  192 P (see  FIG.  6   ) is applied. The second point E 2   a ′ may be referred to as a second terminal. 
     The second line E 2   b ′ may connect the second point E 2   a ′ and the pair of second circles E 21  and E 22 . 
     The pair of second circles E 21  and E 22  may be spaced apart from each other in the length direction of the substrate B. The pair of second circles E 21  and E 22  may have a shape corresponding to each other. For example, any one of the pair of second circles E 21  and E 22  may have a shape which is a shape of the other that is rotated counterclockwise or clockwise by 90 degrees. In this case, the description of any one of the pair of second circles E 21  and E 22  may be identically applied to the other one. In addition, the second circle E 21 , which is any one of the pair of second circles E 21  and E 22 , may include a second outer circle E 21   c  and a second inner circle E 21   d.    
     The second outer circle E 21   c  and the second inner circle E 21   d  may be concentric. A diameter of the second outer circle E 21   c  may be greater than a diameter of the second inner circle E 21   d . A portion of the aforementioned second line E 21   b  may be connected to the second outer circle E 21   c  and the second inner circle E 21   d  from between the second outer circle E 21   c  and the second inner circle E 21   d.    
     In addition, the second outer circle E 21   c  may include second outer needles E 21   cn . In addition, the second inner circle E 21   d  may include second inner needles E 21   dn . For example, the number of the second outer needles E 21   cn  may be greater than the number of the second inner needles E 21   dn . Meanwhile, a barrier (no reference numeral) may be located between the second outer circle E 21   c  and the second inner circle E 21   d , and may minimize discharge interference between the second outer needle E 21   cn  and the second inner needle E 21   dn.    
     A ground electrode E 3 ′ may be formed on the second surface Bb of the substrate B. The ground electrode E 3 ′ may include a metal material such as copper Cu. For example, the ground electrode E 3 ′ may include a ground point E 3   a ′, a connector E 3   b ′, a first ground electrode E 31 ′, and a second ground electrode E 32 ′. The ground point E 3   a ′ may be connected to a wire L 0  (see  FIG.  6   ). The connector E 3   b ′ may connect the ground point E 3   a ′ with the first and second ground electrodes E 31 ′ and E 32 ′. 
     In addition, in a thickness direction of the substrate B, the first ground electrode E 31 ′ may be aligned with the first discharge electrode E 1 ′. The first ground electrode E 311 , E 312  may have a shape corresponding to a pair of first circles E 11  and E 12 . 
     In addition, in the thickness direction of the substrate B, the second ground electrode E 32 ′ may be aligned with the second discharge electrode E 2 ′. The second ground electrode E 321 , E 322  may have a shape corresponding to a pair of second circles E 21  and E 22 . 
     Accordingly, when a high voltage is applied to the discharge electrodes E 1 ′ and E 2 ′ by the voltage generator  192 P, the discharge electrodes E 1 ′ and E 2 ′ may generate a negative ion and/or a positive ion. That is, the first discharge electrode E 1 ′ may be a negative ion discharge electrode that generates a negative ion or a positive ion discharge electrode that generates a positive ion. In addition, the second discharge electrode E 2 ′ may be a negative ion discharge electrode that generates a negative ion or a positive ion discharge electrode that generates a positive ion. 
     Referring to  FIG.  11   , a first protection layer Ct may be formed on the first surface Bt of the substrate B, and may be located around the discharge electrodes E 1 ′ and E 2 ′ or the discharge electrodes E 1  and E 2  (see  FIG.  7   ). A second protection layer Cb may be formed on the second surface Bb of the substrate B, and may be located around the ground electrode E 31 ′, E 32 ′ or the ground electrode E 31 , E 32  (see  FIG.  8   ). 
     A first coating layer Mt may be formed on the surface of the discharge electrodes E 1 ′ and E 2 ′ or the discharge electrodes E 1  and E 2  (see  FIG.  7   ). A second coating layer Mb may be formed on the surface of the ground electrode E 31 ′, E 32 ′ or the ground electrode E 31 , E 32  (see  FIG.  8   ). For example, the first coating layer Mt and the second coating layer Mb may include a metal material such as gold Au. 
     Meanwhile, a photocatalyst Lt may be coated on the surface of the first protection layer Ct. The photocatalyst Lt may include tungsten oxide, titanium oxide, zinc oxide, or zirconium oxide. The photocatalyst Lt may be activated by light. For example, the photocatalyst Lt may be activated by light in an ultraviolet wavelength band. 
     Accordingly, as a high voltage is applied to the discharge electrodes E 1 ′ and E 2 ′ or the discharge electrodes E 1  and E 2  (see  FIG.  7   ), a plasma discharge may be generated, and a ultraviolet light (UV) that is generated due to the plasma discharge may activate the photocatalyst Lt. In this case, radical and ion may be generated, and oxidation of organic matter may be promoted to help sterilization and deodorization. 
     Referring to  FIG.  12   , the fan  193  may include a fan housing  193   a , a motor  193   b , a holder  193   c , a hub  193   d , and a plurality of blades  193   e.    
     The fan housing  193   a  may be opened vertically, and the remaining components of the fan  193  excluding the fan housing  193   a  may be located in the internal space of the fan housing  193   a.    
     For example, the fan housing  193   a  may include a first flat plate portion  193   a   1 , a second flat plate portion  193   a   2 , and a pillar portion  193   a   3  formed as one body. The first flat plate portion  193   a   1  may form an upper surface of the fan housing  193   a , and the second flat plate portion  193   a   2  may form a lower surface of the fan housing  193   a . The pillar portion  193   a   3  may be located between the first flat plate portion  193   a   1  and the second flat plate portion  193   a   2 , and may have a flat cylinder shape. The inner space of the fan housing  193   a  may be formed to vertically penetrate the first flat plate portion  193   a   1 , the pillar portion  193   a   3 , and the second flat plate portion  193   a   2 . The inner space may communicate with the discharge hole  191   h.    
     The motor  193   b  may provide a rotational force. The motor  193   b  may be an axial-flow fan motor. The motor  193   b  may be located in the inner space of the fan housing  193   a . A rotation shaft  193   b   1  (see  FIG.  13   ) of the motor  193   b  may extend downward from the motor  193   b . The rotation shaft  193   b   1  of the motor  193   b  may be coaxial with the central shaft of the fan  193 . 
     One side of the holder  193   c  may be fixed to the upper surface of the motor  193   b , and the other side of the holder  193   c  may be fixed to the inner side of the fan housing  193   a.    
     For example, the holder  193   c  may include a cap  193   c   1  and arms  193   c   2 . The cap  193   c   1  may cover the upper surface of the motor  193   b , and the motor  193   b  may be fixed thereto. The arms  193   c   2  may protrude from the side surface of the cap  193   c   1  to the inner side of the fan housing  193   a , and may be fixed to the inner side of the fan housing  193   a . These arms  193   c   2  may be spaced apart from each other in the circumferential direction of the cap  193   c   1 , and it is possible to minimize the flow resistance of the air passing around the arms  193   c   2 . 
     The hub  193   d  may be located in the lower side of the motor  193   b , and may be fixed to the rotation shaft  193   b   1  (see  FIG.  13   ) of the motor  193   b . The hub  193   b  may have a cup shape as a whole. 
     The plurality of blades  193   e  may be formed on the outer circumferential surface of the hub  193   d , and may be spaced apart from each other in the circumferential direction of the hub  193   d . The distal end of the blade  193   e  may be spaced apart from the inner side of the fan housing  193   a.    
     Accordingly, when the motor  193   b  is driven, the plurality of blades  193   e  may rotate in the rotational direction of the rotation shaft  193   b   1  (see  FIG.  13   ). At this time, the air located in the upper side of the fan  193  may be introduced in the shaft direction of the fan  193 , and may be discharged to the lower side of the fan  193 . 
     Referring to  FIGS.  12  and  13   , a groove  191   m  may be formed while being depressed downward from the upper surface of the seating portion  191   b   1 , and may extend along the circumference of the seating portion  191   b   1 . The plurality of fastening holes  191   m   1 ,  191   m   2 ,  191   m   3 , and  191   m   4  (see  FIGS.  5  and  12   ) may be formed on the groove  191   m , and may be adjacent to corners of the groove  191   m . In the up-down direction, the groove  191   m  may be aligned with the lower surface of the second flat plate portion  193   a   2 . 
     Accordingly, the second flat plate portion  193   a   2  of the fan housing  193   a  may be seated in the groove  191   m . Each of the plurality of fastening members such as a screw or a long bolt may penetrate the first flat plate portion  193   a   1  and the second flat plate portion  193   a   2 , and may be fastened to each of a plurality of fastening holes  191   m   1 ,  191   m   2 ,  191   m   3 , and  191   m   4 . 
     In this case, in the horizontal direction, the ionizer  192  coupled to the receiving portion  191   b   2  may be located outside the fan  193  coupled to the body  191   b   1 . In addition, in the vertical direction, the case hole  192   g  of the ionizer  192  may be located in the lower side of the fan  193 . 
     Accordingly, the ions generated by the ionizer  192  may be carried by the airflow of the fan  193  and flow to the lower side of the discharge hole  191   h . That is, the ions generated by the ionizer  192  may be distributed over an entire sterilization target space (particularly, a part far away from or cornered from the ion generating device) by the fan  193 . 
     Referring to  FIG.  14   , the ion generating device  190 ′ may include at least two or more ionizers  192   a  and  192   b . The description of the ionizer  192  described above with reference to  FIG.  13    and the like may be identically applied to at least two or more ionizers  192   a  and  192   b.    
     For example, the ion generating device  190 ′ may include a first ionizer  192   a  and a second ionizer  192   b  that face each other with respect to the fan  193 . The first ionizer  192   a  may be inserted into the slot  191 S of the receiving portion  191   b   2  provided in the first side BS 1  (see  FIG.  5   ) of the seating portion  191   b   1 . The second ionizer  192   b  may be inserted into the slot  191 S of the receiving portion  191   b   3  provided in the third side BS 3  (see  FIG.  5   ) of the seating portion  191   b   1 . 
     In addition, the second ionizer  192   b  may be symmetrical with the first ionizer  192   a  with respect to the fan  193 . That is, the case hole  192   g  of the first ionizer  192   a  and the case hole  192   g  of the second ionizer  192   b  may face the discharge hole  191   h . Accordingly, the ion supply amount of the ion generating device  190 ′ may increase. 
     Referring to  FIGS.  15  to  17   , the ion generating device  190  may include one ionizer  192 . Alternatively, the ion generating device  190 ′ may include two to four ionizers  192   a ,  192   b ,  192   c , and  192   d . In the ionizers  192   a ,  192   b ,  192   c , and  192   d , each case hole  192   g  (see  FIGS.  13  and  14   ) may face the discharge hole  191   h.    
     Referring to  FIG.  15   , the ionizer may be a bipolar ionizer. That is, the first discharge electrode E 1 , E 1 ′ and the second discharge electrode E 2 , E 2 ′ of the ion generator  192 E may generate ions having a different polarity. When the first discharge electrode E 1 , E 1 ′ generates positive ions, the second discharge electrode E 2 , E 2 ′ may generate negative ions. When the first discharge electrode E 1 , E 1 ′ generates negative ions, the second discharge electrode E 2 , E 2 ′ may generate positive ions. Accordingly, the ionizer may generate positive ions and negative ions. 
     Referring to  FIG.  15 A , the ion generating device  190  may include one ionizer  192 . The ionizer  192  may be located outside the first side BS 1  (see  FIG.  5   ) of the seating portion  191   b   1 . For example, the first discharge electrode E 1 , E 1 ′ may generate negative ions, and the second discharge electrode E 2 , E 2 ′ may generate positive ions. 
     Referring to  FIG.  15 B , the ion generating device  190 ′ may include a first ionizer  192   a  and a second ionizer  192   b . The first ionizer  192   a  may be located outside the first side BS 1  (see  FIG.  5   ) of the seating portion  191   b   1 . The second ionizer  192   b  may be located outside the third side BS 3  (see  FIG.  5   ) of the seating portion  191   b   1 . For example, the first discharge electrode E 1 , E 1 ′ of the first ionizer  192   a  may generate negative ions, and the second discharge electrode E 2 , E 2 ′ may generate positive ions. 
     In this case, the first discharge electrode E 1 , E 1 ′ of the second ionizer  192   b  may face the second discharge electrode E 2 , E 2 ′ of the first ionizer  192   a  and generate positive ions. In addition, the second discharge electrode E 2 , E 2 ′ of the second ionizer  192   b  may face the first discharge electrode E 1 , E 1 ′ of the first ionizer  192   a , and may generate negative ions. Accordingly, neutralization between the ions generated by the first ionizer  192   a  and the ions generated by the second ionizer  192   b  may be minimized. 
     Referring to  FIG.  15 C , the ion generating device  190 ′ may include a first ionizer  192   a , a second ionizer  192   b , and a third ionizer  192   c . The third ionizer  192   c  may be located outside the fourth side BS 4  (see  FIG.  5   ) of the seating portion  191   b   1 . For example, the first discharge electrode E 1 , E 1 ′ of the third ionizer  192   c  may generate positive ions, and the second discharge electrode E 2 , E 2 ′ may generate negative ions. 
     Referring to  FIG.  15 D , the ion generating device  190 ′ may include a first ionizer  192   a , a second ionizer  192   b , a third ionizer  192   c , and a fourth ionizer  192   d . The fourth ionizer  192   d  may be located outside the second side BS 2  (see  FIG.  5   ) of the seating portion  191   b   1 . For example, the first discharge electrode E 1 , E 1 ′ of the third ionizer  192   c  may generate positive ions, and the second discharge electrode E 2 , E 2 ′ may generate negative ions. 
     In this case, the first discharge electrode E 1 , E 1 ′ of the fourth ionizer  192   d  may face the second discharge electrode E 2 , E 2 ′ of the third ionizer  192   c , and generate negative ions. In addition, the second discharge electrode E 2 , E 2 ′ of the fourth ionizer  192   d  may face the first discharge electrode E 1 , E 1 ′ of the third ionizer  192   c , and may generate positive ions. Accordingly, neutralization between ions generated by the first to fourth ionizers  192   a ,  192   b ,  192   c , and  192   d  may be minimized. 
     Referring to  FIGS.  16  and  17   , the ionizer may be a unipolar ionizer. That is, the first discharge electrode E 1 , E 1 ′ and the second discharge electrode E 2 , E 2 ′ of the ion generator  192 E may generate ions having the same polarity. 
     Referring to  FIG.  16   , for example, the first discharge electrode E 1 , E 1 ′ and the second discharge electrode E 2 , E 2 ′ may generate positive ions. 
     As another example with reference to  FIG.  17   , the first discharge electrode E 1 , E 1 ′ and the second discharge electrode E 2 , E 2 ′ may generate negative ions. 
     Accordingly, the ionizer may generate positive ions or negative ions. In addition, it is possible to prevent neutralization between ions generated by the ionizers  192   a ,  192   b ,  192   c , and  192   d.    
     Referring to  FIG.  18   , a controller C of the air conditioner may be electrically connected to components of the air conditioner. 
     The controller C may be electrically connected to the outdoor unit  20 , and may control the operation of a compressor of the outdoor unit  20 . The controller C may be electrically connected to the blower  16  and the exhaust fan  18 , and may control the operations of the blower  16  and the exhaust fan  18 . The controller C may be electrically connected to the motor  13   p , and may control the operation of the recovery wheel  13  through the motor  13   p . The controller C may be electrically connected to the gas furnace  100 , and may control the operation of the gas furnace  100 . 
     In addition, the controller C may control the operations of the ionizer  192  and the fan  193  of the ion generating device  190 ,  190 ′. 
     Referring to  FIGS.  18  and  19   , the controller C may determine whether an air conditioning mode entry condition is satisfied (S 1 ). For example, the air conditioning mode entry condition may be satisfied according to a user&#39;s desire. For another example, the air conditioning mode entry condition may be satisfied when a difference between a desired indoor temperature input to an indoor thermostat and a current indoor temperature detected by a thermocouple of the thermostat exceeds a reference range. 
     When the air conditioning mode entry condition is satisfied (S 1 : Yes), the controller C may perform an air conditioning operation through the air conditioner  1  (see  FIG.  1   ) (S 10 ). Specifically, the controller C may stop the operation of the ion generating device  190 ,  190 ′ (S 11 ), and operate the outdoor unit  20 , the blower  16 , and the exhaust fan  18  (S 12 ). In addition, if indoor heating is required, the controller C may also operate the gas furnace  100 . 
     Accordingly, the air conditioner  1  may heat and cool an indoor space, or ventilate the indoor space. 
     When the air conditioning mode entry condition is satisfied (S 1 : No), the controller C may perform a sterilization operation through the air conditioner  1  (see FIG.  1 ) (S 20 ). Specifically, the controller C may stop the operations of the outdoor unit  20 , the blower  16 , and the exhaust fan  18  (S 21 ). In addition, when the gas furnace  100  is in operation, the controller C may also stop the operation of the gas furnace  100 . Then, the controller C may operate the ion generating device  190 ,  190 ′ (S 22 ). 
     Accordingly, the air conditioner  1  can sterilize the inside of the ventilation device  10  (see  FIG.  1   ). 
     Referring back to  FIG.  1   , the ion generating device  190  may include a first ion generating device  190   a  and a second ion generating device  190   b . The first ion generating device  190   a  may be located between the recovery wheel  13  and the heat exchanger  14 , and may be coupled to the inner side of the top part  10 T which is a portion forming the first long side LS 1  of the housing  10 H. The second ion generating device  190   b  may be located between the heat exchanger  14  and the reheater  15 , and may be coupled to the inner side of the top part  10 T which is a portion forming the first long side LS 1  of the housing  10 H. 
     Meanwhile, in some embodiments, any one of the first ion generating device  190   a  and the second ion generating device  190   b  may be omitted. At this time, considering that a space in which the first ion generating device  190   a  is installed is located upstream of a space in which the second ion generating device  190   b  is installed, preferably, the first ion generating device  190   a  may be provided in the ventilation device  10 . 
     Referring to  FIGS.  1  and  20   , the first space I may be a portion of the internal space of the housing  10 H, and may be a space formed between the first portion  13   a  of the recovery wheel  13  and the heat exchanger  14 . A portion of the top part  10 T of the housing  10 H, a portion of the bottom part  10 B of the housing  10 H, and the damper mount  17  may define a portion of the boundary of the first space I. 
     The upper end of the first portion  13   a  of the recovery wheel  13  may be spaced downward from the top part  10 T. The upper end of the heat exchanger  14  may be spaced downward from the top part  10 T. In the up-down direction, a first gap g 1  between the top part  10 T and the upper end of the first portion  13   a  may be smaller than or equal to a second gap g 2  between the top part  10 T and the upper end of the heat exchanger  14 . 
     The first ion generating device  190   a  may be coupled to the inner side of the top part  10 T from between the first portion  13   a  and the heat exchanger  14 . For example, the volume of the first ion generating device  190   a  may be 0.5% or less of the volume of the first space I. For example, the height h 10  of the first ion generating device  190   a  may be smaller than the first gap g 1 . That is, the lower end of the first ion generating device  190   a  may be located in the upper side of the upper end of the first portion  13   a  and the upper end of the heat exchanger  14 . As another example, the height h 10  of the first ion generating device  190   a  may be equal to or slightly greater than the first gap g 1 . That is, the lower end of the first ion generating device  190   a  may be located parallel to or slightly lower than the upper end of the first portion  13   a.    
     Accordingly, the first ion generating device  190   a  may be spaced apart from the main airflow of air that sequentially passes through the first portion  13   a  and the heat exchanger  14  by the blower  16 . In other words, in the air conditioning mode, an increase in air flow resistance by the first ion generating device  190   a  can be minimized. In addition, particularly during a cooling operation, the first space I may be a space having a low temperature and low humidity, and may be a good environment for microorganisms or bacteria to grow. That is, the first ion generating device  190   a  may remove microorganisms or bacteria inhabiting the first space I by providing ions to the first space I. 
     Meanwhile, the height h 10  of the first ion generating device  190   a  may be the sum of a first height h 11  and a second height h 12 . The first height h 11  may be a distance between the lower end of the base  191   a  and the upper end of the fan  193 . The second height h 12  may be a distance between the upper end of the fan  193  and the upper end of the foot  191   d . In other words, the upper end of the fan  193  may be spaced downward from the top part  10 T by the second height h 12 . 
     Accordingly, air may be introduced in the shaft direction of the fan  193  through between the top part  10 T and the upper end of the fan  193 . 
     Referring to  FIGS.  1  and  21   , the second space II may be a portion of the inner space of the housing  10 H, and may be a space in which the heat exchanger  14  and the reheater  15  are disposed. A portion of the top part  10 T of the housing  10 H and a portion of the bottom part  10 B of the housing  10 H may define a portion of a boundary of the second space II. 
     The reheater  15  may be spaced downward from the top part  10 T. In the up-down direction, a third gap g 3  between the top part  10 T and the upper end of the reheater  15  may be greater than the second gap g 2  between the top part  10 T and the upper end of the heat exchanger  14 . 
     The second ion generating device  190   b  may be coupled to the inner side of the top part  10 T from between the heat exchanger  14  and the reheater  15 . For example, the volume of the second ion generating device  190   b  may be 0.5% or less of the volume of the second space II. For example, the height h 20  of the second ion generating device  190   b  may be smaller than the second gap g 2 . That is, the lower end of the second ion generating device  190   b  may be located in the upper side of the upper end of the heat exchanger  14  and the upper end of the reheater  15 . As another example, the height h 20  of the second ion generating device  190   b  may be equal to or slightly larger than the second gap g 2 . That is, the lower end of the second ion generating device  190   b  may be located parallel to or slightly lower than the upper end of the heat exchanger  14 . 
     Accordingly, the second ion generating device  190   b  may be spaced apart from the main airflow of air that sequentially passes through the heat exchanger  14  and the reheater  15  by the blower  16 . In other words, in the air conditioning mode, an increase in air flow resistance by the second ion generating device  190   b  can be minimized. In addition, particularly during a cooling operation, the second space II may be a space having a fairly low temperature and a fairly low humidity, and may be a good environment for microorganisms or bacteria to grow. That is, the second ion generating device  190   b  may remove microorganisms or bacteria inhabiting the second space II by providing ions to the second space II. 
     Meanwhile, the height h 20  of the second ion generating device  190   b  may be the sum of the first height h 21  and the second height h 22 . The first height h 21  may be a distance between the lower end of the base  191   a  and the upper end of the fan  193 . The second height h 22  may be a distance between the upper end of the fan  193  and the upper end of the foot  191   d . In other words, the upper end of the fan  193  may be spaced downward from the top part  10 T by the second height h 22 . 
     Accordingly, air may be introduced in the shaft direction of the fan  193  through between the top part  10 T and the upper end of the fan  193 . 
     Referring back to  FIGS.  20  and  21   , the height h 10  of the first ion generating device  190   a  and the height h 20  of the second ion generating device  190   b  may be the same. 
     For example, the number of ionizers  192  provided in the first ion generating device  190   a  may be the same as the number of ionizers  192  provided in the second ionizer  190   b . In this case, the diameter d 10  of the base  191   a  of the first ionizer  190   a  may be the same as the diameter d 20  of the base  191   a  of the second ionizer  190   b . The diameter d 10  or d 20  of the base  191   a  may increase as the number of ionizers  192  provided in the ion generating device  190   a  or  190   b  increases. That is, the diameter (see  FIG.  14   ) of the base  191   a  of the ion generating device  190   a  or  190   b  including two ionizers  192   a  and  192   b  may be larger than the diameter (see  FIG.  13   ) of the base  191   a  of the ion generating device  190   a  or  190   b  including one ionizer  192 . 
     For another example, the number of ionizers  192  provided in the first ion generating device  190   a  may be different from the number of ionizers  192  provided in the second ion generating device  190   b . In this case, the diameter d 10  of the base  191   a  of the first ionizer  190   a  may be different from the diameter d 20  of the base  191   a  of the second ionizer  190   b . Considering that the first space (I) is located upstream of the second space (II), preferably, the number of ionizers  192  provided in the first ion generating device  190   a  may be greater than the number of ionizers  192  provided in the second ion generating device  190   b.    
     Referring to  FIG.  22   , it can be seen that the amount of ions (EA/cc) generated by the ion generating device  190   a ,  190   b  varies according to the second height h 12 , h 22  described above with reference to  FIGS.  20  and  21   . 
     Specifically, when the second height h 12 , h 22  is 30 mm, ions of 84,000 EA/cc may be generated by the ion generating device  190   a ,  190   b . When the second height h 12 , h 22  is 50 mm, ions of 110,000 EA/cc may be generated in the ion generating device  190   a ,  190   b . When the second height h 12 , h 22  is 70 mm, 113,000 EA/cc of ions may be generated by the ion generating device  190   a ,  190   b . That is, as the second height h 12 , h 22  is increased, the amount of ions EA/cc generated by the ion generating device  190   a ,  190   b  may increase, but may be gradually saturated. For example, the second heights h 12  and h 22  may be 50 mm or more. 
     Referring to  FIG.  23   , the first space I may be larger than the second space II. In the front-rear direction, the width w 1  of the first space I may be greater than the width w 2  of the second space II. In the left-right direction, the length p 2  of the first space I may be equal to the length p 2  of the second space II. 
     The virtual center line HL may pass through a center (see P 1 ) of the top part  10 T (see  FIG.  20   ) defining the upper boundary of the first space I and a center (see P 1 ) of the top part  10 T (see  FIG.  21   ), defining the upper boundary of the second space II, and may extend in the front-rear direction. 
     The virtual first line VL 1  may pass through the center of the top part  10 T (see  FIG.  18   ) defining the upper boundary of the first space I, and may extend in the left-right direction. 
     The virtual second line VL 2  may pass through the center of the top part  10 T (see  FIG.  19   ) defining the upper boundary of the second space II, and may extend in the left-right direction. 
     That is, the center line HL and the first line VL 1  may intersect at the center of the top part  10 T defining the upper boundary of the first space I. Moreover, the center line HL and the second line VL 2  may intersect at the center of the top part  10 T defining the upper boundary of the second space II. 
     Referring to  FIGS.  23  and  24   , it can be seen that the ion concentration EA/cc of the bottom surface varies according to the positions of the first ion generating device  190   a  and the second ion generating device  190   b . For example, the ion concentration EA/cc of the bottom surface of the first space I may be measured at a point DP on the bottom part  10 B defining the lower boundary of the first space I. 
     Referring to  FIG.  24 A , for example, the ion concentration of the bottom surface according to the position of the first ion generating device  190   a  on the center line HL may be checked. A target point TP may be located at an intersecting point of the center line HL and the first line VL 1 . A first comparison point CP 1  and a second comparison point CP 2  may be located on the center line HL and may face each other with respect to the target point TP. When the first ion generating device  190   a  is disposed at the target point TP, it can be seen that the ion concentration of the bottom surface is measured to be high, in comparison with a case where the first ion generating device  190   a  is disposed at the first comparison point CP 1  or the second comparison point CP 2 . 
     Referring to  FIG.  24 B , for example, the ion concentration of the bottom surface according to the position of the first ion generating device  190   a  on the first line VL 1  may be checked. The target point TP may be located at an intersecting point of the center line HL and the first line VL 1 . A third comparison point CP 3  and a fourth comparison point CP 4  may be located on the first line VL 1  and may face each other with respect to the target point TP. When the first ion generating device  190   a  is disposed at the target point TP, it can be seen that the ion concentration of the bottom surface is measured to be high in comparison with a case where the first ion generating device  190   a  is disposed at the third comparison point CP 3  or the fourth comparison point CP 4 . 
     Accordingly, preferably, the first ion generating device  190   a  may be disposed at the center of the top part  10 T (see  FIG.  20   ) defining the upper boundary of the first space I. Similarly, preferably, the second ion generating device  190   b  may be disposed at the center of the top part  10 T (see  FIG.  21   ) defining the upper boundary of the second space II. 
     Referring to  FIGS.  25  to  27   , the leg  191   c  may include a first part  1911 , a second part  1912 , and a third part  1913 . The first part  1911  may be fixed to the upper surface of the base  191   a  (see  FIG.  4   ). The third part  1913  may include a foot  191   d  (see  FIG.  4   ). The second part  1912  may be located between the first part  1911  and the third part  1913 . 
     The first part  1911  may extend in a vertical direction. The first part  1911  may have a hollow cylinder shape or a hollow square bar shape as a whole. A protrusion  1911   a  may be formed in the inner side of the first part  1911 . The protrusion  1911   a  may be located on a symmetrical surface of the first part  1911 . Here, one portion and the remaining portion of the first part  1911  may be symmetrical with each other with the symmetrical surface interposed therebetween. For example, the protrusion  1911   a  may include a pair of protrusions spaced apart from each other in the horizontal direction. 
     The second part  1912  may extend in a vertical direction. The second part  1912  may have a hollow cylinder shape or a hollow square bar shape as a whole. The diameter or width of the second part  1912  may be smaller than the diameter or width of the first part  1911 . The lower end of the second part  1912  may be inserted into the first part  1911 . A guide groove  1912   a  may be formed outside the second part  1912 , and may be formed to be elongated in a vertical direction. The guide groove  1912   a  may be located on a symmetrical surface of the second part  1912 . Here, one portion and the remaining portion of the second part  1912  may be symmetrical with each other with the symmetrical surface interposed therebetween. For example, the guide groove  1912   a  may include a pair of guide grooves spaced apart from each other in the horizontal direction. 
     In addition, the protrusion  1911   a  may be vertically movably inserted into the guide groove  1912   a . That is, the first part  1911  and the second part  1912  may be slide-coupled. The lower end of the guide groove  1912   a  may be blocked. The downward movement of the first part  1911  and the protrusion  1911   a  may be restricted by the lower end of the guide groove  1912   a . The lower end of the guide groove  1912   a  may be referred to as a lower stopper. 
     The third part  1913  may extend in a vertical direction. The third part  1913  may have a solid cylinder shape or a solid square bar shape as a whole. A diameter or a width of the third part  1913  may be greater than a diameter or a width of the second part  1912 . For example, the diameter or width of the third part  1913  may be substantially the same as the diameter or width of the first part  1911 . The lower end of the third part  1913  may contact the upper end of the second part  1912 . For example, the third part  1913  may be formed as one body with the second part  1912 . The upward movement of the first part  1911  and the protrusion  1911   a  may be restricted by the lower end of the third part  1913 . The lower end of the third part  1913  may be referred to as an upper stopper. 
     In addition, a fixing portion  1913   a  may protrude from the lower end of the third part  1913  toward the inside of the second part  1912 . 
     A linear actuator  1910  may be located inside the first part  1911  and the second part  1912 . The linear actuator  1910  may include a linear motor  1910   a  and a rod  1910   b.    
     The linear motor  1910   a  may be located closer to the lower end of the first part  1911  than the upper end. The linear motor  1910   a  may be fixed to the inner side of the first part  1911 . 
     The rod  1910   b  may extend upward from the linear motor  1910   a  and may be fixed to the fixing portion  1913   a . The rod  1910   b  may be vertically moved by the linear motor  1910   a.    
     Accordingly, when the linear motor  1910   a  is operated, the first part  1911  may ascend or descend along the second part  1912 . In other words, in the vertical direction, the leg  1911  may be compressed or expanded. The leg  191   c  may be referred to as an extendable leg or a stackable leg. 
     Referring to  FIG.  26   , for example, in a first state of the ion generating device  190 , the first part  1911  of the leg  191   c  may contact the third part  1913 . That is, the second part  1912  (see  FIG.  25   ) of the leg  191   c  may be hidden inside the first part  1911 . The height of the leg  191   c  may be equal to the sum of the height ha of the first part  1911  and the height hc of the third part  1913 . 
     In this case, the lower end of the ion generating device  190  may be located in the upper side of the reference line CL. Alternatively, the lower end of the ion generating device  190  may be located parallel to or slightly below the reference line CL. Here, the reference line CL may be a virtual line that passes through the upper end of the first portion  13   a  of the recovery wheel  13  and extends in the horizontal direction (see  FIGS.  20  and  21   ). 
     Referring to  FIG.  27   , for example, in a second state of the ion generating device  190 , the first part  1911  of the leg  191   c  may be spaced apart from the third part  1913 . That is, the second part  1912  of the leg  191   c  may be exposed between the first part  1911  and the third part  1913 . The height of the leg  191   c  may be equal to the sum of the height ha of the first part  1911 , the height hc of the third part  1913 , and the height hb of the exposed portion of the second part  1912 . 
     In this case, the lower end of the ion generating device  190  may be located in the lower side of the reference line CL (see OG). In addition, the distance between the upper end of the fan  193  and the foot  191   d  may be increased (see h 13 ). 
     Referring to  FIG.  28   , the controller C of the air conditioner may be electrically connected to the ion generating device  190 ,  190 ′. The controller C may control the operations of the ionizer  192 , the fan  193 , and the linear actuator  1910  of the ion generating device  190 ,  190 ′. 
     Referring to  FIGS.  28  and  29   , the controller C may determine whether the air conditioning mode entry condition is satisfied (S 1 ). For example, the air conditioning mode entry condition may be satisfied according to a user&#39;s desire. For another example, the air conditioning mode entry condition may be satisfied if a difference between a desired indoor temperature input to the indoor thermostat and a current indoor temperature detected by the thermocouple of the thermostat exceeds a reference range. 
     When the air conditioning mode entry condition is satisfied (S 1 : Yes), the controller C may perform the air conditioning operation through the air conditioner  1  (see  FIG.  1   ) (S 10 ′). Specifically, the controller C may stop the operation of the ion generating device  190 ,  190 ′(S 11 ), and change the ion generating device  190 ,  190 ′ to the first state (see  FIG.  26   ) ( 513 ). In addition, the controller C may operate the outdoor unit  20 , the blower  16 , and the exhaust fan  18  (S 12 ). In addition, if indoor heating is required, the controller C may also operate the gas furnace  100 . 
     Accordingly, the air conditioner  1  may cool and heat the indoor space, or ventilate the indoor space. Here, the first state of the ion generating device  190 ,  190 ′ may be a state capable of minimizing the flow resistance of the air flowing by the blower  16 . 
     When the air conditioning mode entry condition is not satisfied (S 1 : No), the controller C may perform a sterilization operation through the air conditioner  1  (see  FIG.  1   ) (S 20 ′). Specifically, the controller C may stop the operations of the outdoor unit  20 , the blower  16 , and the exhaust fan  18 . In addition, when the gas furnace  100  is in operation, the controller C may also stop the operation of the gas furnace  100 . Then, the controller C may change the ion generating device  190 ,  190 ′ to the second state (see  FIG.  27   ) ( 523 ), and operate the ion generating device  190 ,  190 ′ (S 22 ). 
     Accordingly, the air conditioner  1  can sterilize the inside of the ventilation device  10  (see  FIG.  1   ). Here, the second state of the ion generating device  190 ,  190 ′ may be a state that can maximize the amount of ions discharged from the ion generating device  190 ,  190 ′ and secure a high sterilization performance. 
     The effects of the ion generating device and the air conditioner having the same according to the present disclosure will be described as follows. 
     According to at least one of the embodiments of the present disclosure, it is possible to provide an air conditioner capable of heating or cooling outdoor air through a heat exchanger and supplying to a room. 
     According to at least one of the embodiments of the present disclosure, it is possible to provide an ion generating device capable of removing bacteria or microorganisms propagating in the housing of an air conditioner in which a heat exchanger is installed. 
     According to at least one of the embodiments of the present disclosure, it is possible to provide an ion generating device that can be continuously operated for a long time by applying a high voltage to the discharge electrode, and has components that are detachably assembled so as to achieve easy maintenance, management, and maintenance. 
     According to at least one of the embodiments of the present disclosure, a fan of ion generating device may provide ions generated by the ion generating device to the entire space to be sterilized. 
     According to at least one of the embodiments of the present disclosure, it is possible to provide an ion generating device including a fan operated independently of a blower for air conditioning operation. 
     According to at least one of the embodiments of the present disclosure, since the ion generating device is located outside of the airflow passing through the heat exchanger, it is possible to minimize air flow resistance during air conditioning operation. 
     According to at least one of the embodiments of the present disclosure, the ion generating device is provided with a variable height through the elastic legs, so that it can have a height that minimizes air flow resistance during the air conditioning operation and can have a height that can maximize the sterilization performance during the sterilization operation. 
     According to at least one of the embodiments of the present disclosure, it is possible to provide a coupling structure and an optimal installation position of the ventilation device and the ion generating device of an air conditioner capable of maximizing the amount of ions generated by the ion generating device. 
     According to at least one of the embodiments of the present disclosure, various examples regarding the shape and number of ionizers provided in the ion generating device may be provided. 
     Any or other embodiments of the present disclosure described above are not mutually exclusive or distinct. Any or other embodiments of the present disclosure described above may be used jointly or combined in each configuration or function. 
     For example, it means that configuration A described in a specific embodiment and/or drawings may be combined with configuration B described in other embodiments and/or drawings. That is, even if the coupling between the components is not directly described, it means that the coupling is possible except for the case where it is described that the coupling is impossible. 
     The above detailed description should not be construed as restrictive in all respects and should be considered as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present disclosure are included in the scope of the present disclosure.