Patent Publication Number: US-2022226532-A1

Title: Air purifier

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 16/462,865 filed on May 21, 2019, which is the National Stage Entry of International Patent Application No. PCT/KR2017/013191, filed on Nov. 20, 2017, and claims priority from and the benefit of Korean Patent Application No. 10-2016-0155968, filed on Nov. 22, 2016 and Korean Patent Application No. 10-2017-0000352, filed on Jan. 2, 2017, each of which is incorporated by reference for all purposes as if fully set forth herein. 
    
    
     FIELD 
     Exemplary embodiments of the disclosure relate generally to an air purifier. 
     DISCUSSION OF THE BACKGROUND 
     Generally, an air purifier uses a blower, such as a fan, to circulate air through various filters, such as a prefilter, a deodorizing filter, and a HEPA filter, to remove pollutants including fine dust, bacteria, and volatile organic compounds (VOCs) such as formaldehyde from the air. 
     Recently, as it has been known that air pollutants can be released from furniture, office supplies, home appliances, interior paints on new houses, interior goods, automobile interior materials, toilets, and the like, there is a growing interest in indoor air quality. Accordingly, there is an increasing demand for a small air purifier, which is easy to install, simple to use, and does not take up much space, which may be suitable for use in houses, offices, automobiles, and the like. 
     The recent development of semiconductor technology has enabled high efficiency ultraviolet (UV) light emitting diodes to be produced at lower costs. As such, photocatalytic filters are widely used as deodorizing filters. A photocatalytic filter is fabricated by coating an air-permeable material, such as metal foam or porous metal, with a photocatalytic material, such as TiO 2 , ZnO, ZrO 2 , or WO 3 , and can generate hydroxyl radicals to decompose contaminants or odorous substances when irradiated with UV light. Such a photocatalytic filter can be reused through cleaning after a certain period of the usage. 
     However, a typical small air purifier has a structure that makes it difficult to disassemble a case for removing a reusable filter, such as a deodorizing filter or a prefilter, from the air purifier. Therefore, there is a need for an air purifier that allows easy replacement and attachment/detachment of a filter. 
     In addition, the HEPA filter is configured to collect fine dust in air. Thus, the fine dust collected from air adheres to the HEPA filter. In this case, microorganisms such as virus and bacteria contained in the fine dust remain on the HEPA filter, and thus are left inside the air purifier. 
     SUMMARY 
     It is one aspect of the exemplary embodiments to provide an air purifier that allows easy attachment/detachment of a filter upon replacement of the filter in the air purifier. 
     It is another aspect of the exemplary embodiments to provide an air purifier that includes a cover capable of protecting a power controller disposed inside the air purifier from external impact or from contact with other components inside the air purifier. 
     It is a further aspect of the exemplary embodiments to provide an air purifier that can sterilize microorganisms adhered to a HEPA filter. 
     In accordance with one exemplary embodiment, an air purifier including a body, a fan, at least one light source module, a power controller, and a cover is provided. The body is formed on one surface thereof with a suction port and on the other surface thereof with a discharge port, is provided with a power source, and has an inner space through which air flows from the suction port to the discharge port. The fan is disposed in the inner space of the body. The at least one light source module is disposed in the inner space of the body and emits UV light. The power controller is mounted on an inner wall of the body and is physically or electrically connected to the power source to supply power to the light source module. The cover is mounted on the inner wall of the body and is formed to cover the power controller. 
     In accordance with another exemplary embodiment, an air purifier including a body, a fan, at least one filter, at least one light source module, and a door is provided. The body is formed with a suction port, a discharge port, and a filter replacement portion having an opening shape, and has an inner space through which air flows from the suction port to the discharge port. The fan is disposed in the inner space of the body. The at least one filter is disposed in the inner space of the body. The at least one light source module emits UV light toward the filter. The door is mounted on an outer wall of the body to open or close the filter replacement portion. Here, the filter is detachably attached to an interior of the body through the filter replacement portion. 
     According to an exemplary embodiment, the air purifier may be provided with a door to allow replacement of a filter without dissembling the air purifier. 
     According to an exemplary embodiment, the air purifier may be provided with a cover surrounding a power controller to prevent failure of the power controller due to external impact or contact with other components thereof. 
     According to an exemplary embodiment, the air purifier may be adapted to sterilize microorganisms adhered to a HEPA filter, thereby improving air purification performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description serve to explain the inventive concepts. 
         FIG. 1  is a schematic view of an air purifier according to a first exemplary embodiment. 
         FIG. 2  and  FIG. 3  are a diagram and a graph depicting a result of an experiment for testing sterilization of a HEPA filter according to exemplary embodiments. 
         FIGS. 4, 5, 6, 7, 8, 9, 10, and 11  are schematic views of air purifiers according to second to ninth exemplary embodiments. 
         FIG. 12  is a schematic view of an air purifier according to a tenth exemplary embodiment. 
         FIG. 13  is an exploded perspective view of an air purifier according to an eleventh exemplary embodiment. 
         FIG. 14  is a perspective view showing the interior of the air purifier according to the eleventh exemplary embodiment. 
         FIG. 15  is an assembly view of the air purifier according to the eleventh exemplary embodiment. 
         FIG. 16  is a schematic view of an air purifier according to a twelfth exemplary embodiment. 
         FIG. 17  and  FIG. 18  are schematic views of air purifiers according to thirteenth and fourteenth exemplary embodiments. 
         FIG. 19  is a schematic view of an air purifier according to a fifteenth exemplary embodiment. 
         FIG. 20  is a schematic view of an air purifier according to a sixteenth exemplary embodiment. 
         FIG. 21  is a schematic view of an air purifier according to a seventeenth exemplary embodiment. 
         FIG. 22  is a schematic view of an air purifier according to an eighteenth exemplary embodiment. 
         FIG. 23  is a schematic view of an air purifier according to a nineteenth exemplary embodiment. 
         FIG. 24  and  FIG. 25  are schematic views of air purifiers according to twentieth and twenty first exemplary embodiments. 
         FIG. 26  is a schematic view of an air purifier according to a twenty second exemplary embodiment. 
         FIG. 27  is a schematic view of an air purifier according to a twenty third exemplary embodiment. 
         FIG. 28  is a schematic view of an air purifier according to a twenty fourth exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be understood that the following embodiments are provided for complete disclosure and thorough understanding of the invention by those skilled in the art. Therefore, the exemplary embodiment of the disclosure is not limited to the following embodiments and may be embodied in different ways. In addition, widths, lengths, thicknesses, and the like of elements can be exaggerated for clarity and descriptive purposes. When an element or component is referred to as being “on,” “connected to,” or “coupled to” another element or component, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or components may be present therebetween. In addition, spatially relative terms, such as “upper surface,” “lower surface,” “rear surface,” “front surface,” and the like, may be used herein for descriptive purposes and do not restrict a direction in which an element or component is formed. Like reference numerals denote like elements throughout the specification. 
     According to an exemplary embodiment, an air purifier includes a body, a fan, at least one light source module, a power controller, and a cover. The body is formed on one surface thereof with a suction port and on the other surface thereof with a discharge port, is provided with a power source, and has an inner space through which air flows from the suction port to the discharge port. The fan is disposed in the inner space of the body. The at least one light source module is disposed in the inner space of the body and emits UV light. The power controller is mounted on an inner wall of the body and is physically or electrically connected to the power source to supply electric power to the light source module. The cover is mounted on the inner wall of the body and is formed to cover the power controller. 
     The light source module may emit the UV light toward air flowing in the inner space of the body. 
     The body may be further formed at both sides thereof with filter securing portions disposed on the inner wall thereof to receive both sides of the filter inserted thereinto. 
     The fan may be secured to one side of the cover. 
     The body may be further formed with a fan securing portion disposed at one side of the cover to be parallel to the discharge port and securing the fan. 
     The fan secured to the fan securing portion may have a side surface separated from the inner wall of the body. 
     The cover may further include a light source module support. The light source module support may support the light source module to be separated from the cover. 
     The body may be further formed with light source module grooves disposed on the inner wall thereof to receive both sides of the light source module inserted thereinto. 
     The air purifier may further include at least one filter disposed in the inner space of the body. 
     The at least one filter may include at least one of a photocatalytic filter and a HEPA filter. 
     The at least one light source module may emit UV light toward the photocatalytic filter or the HEPA filter, or may include two light source modules, one of which emits UV light toward the photocatalytic filter and the other of which emits UV light toward the HEPA filter. 
     The cover may be formed at the other side thereof with an air flow guide facet tilted to allow air suctioned through the suction port to flow toward the filter. 
     The air flow guide facet may be tilted to have a gradually increasing height from the suction port toward the filter. 
     The air purifier may further include a resilient frame disposed to surround an outer surface of the filter. 
     According to another exemplary embodiment, an air purifier includes a body, a fan, at least one filter, at least one light source module, and a door. The body is formed with a suction port, a discharge port, and a filter replacement portion having an opening shape, and has an inner space through which air flows from the suction port to the discharge port. The fan is disposed in the inner space of the body. The at least one filter is disposed in the inner space of the body. The at least one light source module emits UV light toward the filter. The door is mounted on an outer wall of the body to open or close the filter replacement portion. Here, the filter is detachably attached to an interior of the body through the filter replacement portion. 
     The body may be further formed at both sides thereof with groove-shaped filter securing portions disposed on an inner wall thereof to receive both sides of the filter inserted thereinto. 
     The filter securing portions may extend to the filter replacement portion. Both sides of each of the filter replacement portions have a groove structure depressed along the filter securing portions. 
     The body may be further formed with light source module grooves disposed on the inner wall thereof to receive both sides of the light source module inserted thereinto. 
     The air purifier may further include a resilient frame disposed to surround an outer surface of the filter. 
     The air purifier may further include stoppers protruding to face each other at both sides of an inlet of the filter replacement portion. 
     The at least one filter may include at least one of a photocatalytic filter and a HEPA filter. 
     The at least one light source module may emit UV light toward the photocatalytic filter or the HEPA filter, or may include two light source modules, one of which emits UV light toward the photocatalytic filter and the other of which emits UV light toward the HEPA filter. 
     The air purifier may further include: door guides formed at both sides of the door to continuously protrude from an inner wall of the door; and door guide grooves formed on an outer wall of the body so as to correspond to the door guides. The door guides are inserted into the door guide grooves when the door closes the filter replacement portion. 
     The air purifier may further include: a door securing portion formed at one end of each of the door guides to protrude outwards; and a door securing groove formed at one end of each of the door guide grooves so as to correspond to the door securing portion. The door securing portions are inserted into the door securing grooves when the door closes the filter replacement portion. 
     According to a further exemplary embodiment, an air purifier includes a body, at least one light source module, a cover, a fan securing portion, and a fan. The body is formed on one surface thereof with a suction port and on the other surface thereof with a discharge port, is provided with a power source, and has an inner space through which air flows from the suction port to the discharge port. The at least one light source module is disposed in the inner space of the body and emits UV light. The cover is mounted on the inner wall of the body. The fan securing portion is formed at one side of the cover to be perpendicular to the inner wall of the body on which the cover is mounted. The fan is secured to the fan securing portion. Here, the fan secured to the fan securing portion is separated from the inner wall of the body. 
     Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a schematic view of an air purifier according to a first exemplary embodiment. 
     Referring to  FIG. 1 , an air purifier  100  includes a body  110 , a photocatalytic filter  120 , a HEPA filter  130 , a first light source module  140 , and a second light source module  150 . The air purifier  100  further includes well-known components, such as a fan  180 , and thus, detailed descriptions as to the well-known components will be omitted. Referring to  FIG. 1 , the fan  180  is disposed between a discharge port  113  and a photocatalytic filter  120 . However, the inventive concepts are not limited thereto, and in some exemplary embodiments, the fan  180  may be disposed at any locations inside or outside the air purifier  100 . 
     The body  110  is formed with a suction port  111  and the discharge port  113  on an outer wall thereof. The suction port  111  refers to an opening through which external air is suctioned into an inner space of the body  110 . The discharge port  113  refers to an opening through which air is discharged to the outside after being subjected to sterilization and purification inside the body  110 . The suction port  111  and the discharge port  113  are formed on different surfaces of the body  110 . 
     In the inner space of the body  110 , the photocatalytic filter  120 , the HEPA filter  130 , the first light source module  140 , and the second light source module  150  are sequentially arranged. In addition, the photocatalytic filter  120 , the HEPA filter  130 , the first light source module  140 , and the second light source module  150  are disposed between the suction port  111  and the discharge port  113 . 
     The body  110  is formed on the inner wall thereof with filter securing portions  160  and light source module securing portions  170 . The filter securing portions  160  may secure filters, such as the photocatalytic filter  120  and the HEPA filter  130 , inside the body  110 . In addition, the light source module securing portions  170  may secure the first light source module  140  and the second light source module  150  inside the body  110 . For example, the light source module securing portions  170  may be formed to secure the first light source module  140  and the second light source module  150  along a central line on one surface of each of the photocatalytic filter  120  and the HEPA filter  130 . 
     In the illustrated exemplary embodiment, both sides of each of the photocatalytic filter  120 , the HEPA filter  130 , the first light source module  140 , and the second light source module  150  are inserted into the filter securing portions  160  or the light source module securing portions  170  to be secured to the body  110 . However, the inventive concepts are not limited thereto, and in some exemplary embodiments, the structure for securing the photocatalytic filter  120 , the HEPA filter  130 , the first light source module  140 , and the second light source module  150  inside the body  110  may be variously modified. 
     The body  110  may be formed of metal or a resin material, such as a plastic material. Further, the body  110  may be formed in any structure including a rectangular column shape, a circular column shape, or a conical shape, so long as the body  110  has an inner space. 
     Referring to  FIG. 1 , the second light source module  150 , the HEPA filter  130 , the first light source module  140 , and the photocatalytic filter  120  are sequentially arranged in a direction from the suction port  111  to the discharge port  113 . 
     The photocatalytic filter  120  is formed by coating a photocatalytic material on a base having a plurality of through holes. The base of the photocatalytic filter  120  is formed of a porous ceramic material. Alternatively, the base may be formed of a metal foam material including nickel (Ni), iron (Fe), aluminum (Al), chromium (Cr), and the like. A surface of the base is coated with the photocatalytic material. The photocatalytic material includes at least one selected from among TiO 2 , ZnO, ZrO 2 , and WO 3 . Alternatively, the photocatalytic filter  120  may be made of a photocatalytic material. 
     The first light source module  140  includes first light sources  141  and a first light source substrate  143 . The first light sources  141  are mounted on one surface of the first light source substrate  143 . The first light source module  140  is disposed such that the first light sources  141  face the photocatalytic filter  120  to emit UV light toward the photocatalytic filter  120 . For example, UV light emitted from the first light source module  140  may be UVA having a wavelength in the range of 315 nm to 400 nm. 
     UV light emitted from the first light source module  140  reacts with the photocatalytic material of the photocatalytic filter  120  to form hydroxyl radicals ( 0 . 0 H). The generated hydroxyl radicals remove pollutants or odorous substances through decomposition. In this manner, the air is purified by such photocatalytic reaction while passing through the through holes of the photocatalytic filter  120 . 
     The photocatalytic filter  120  may react to a plurality of ultraviolet wavelengths. If the photocatalytic filter  120  reacts to multiple wavelengths, the range of wavelengths irradiated to the photocatalytic filter  120  is broadened. As the photocatalytic filter  120  responds to a wide range of ultraviolet wavelengths, air purification performance of the air purifier  100  can be improved. 
     The HEPA filter  130  may collect fine dusts in air. Fine dusts having minute particle sizes are harmful to the human body, since such particles cannot be filtered by the upper respiratory systems, such as nose and bronchial tubes. Since the HEPA filter  130  collects fine dusts harmful to the human body, air having passed through the HEPA filter  130  may be free from fine dusts. However, in the HEPA filter  130 , the collected fine dusts adhere to an air inlet side thereof. Microorganisms such as bacteria and viruses are present in the fine dust. Therefore, various microorganisms may be present on the surface of the HEPA filter  130  together with the collected fine dusts. 
     The second light source module  150  includes second light sources  151  and a second light source substrate  153 . The second light sources  151  are mounted on one surface of the second light source substrate  153  to face the HEPA filter  130 . The second light source module  150  emits UV light toward the HEPA filter  130 . A UV light emission direction of the second light source module  150  is a direction of air flowing into the HEPA filter  130 . That is, a portion of the HEPA filter  130  irradiated with UV light is an air inflow surface thereof. For example, UV light emitted from the second light source module  150  is UVC having a wavelength in the range of 200 nm to 290 nm. 
     The second light source module  150  sterilizes the HEPA filter  130  by emitting UV light to the HEPA filter  130 . More specifically, the second light source module  150  sterilizes microorganisms in the fine dust adhered to one side of the HEPA filter  130 . Since the second light source module  150  is disposed to face one side of the HEPA filter  130 , microorganisms adhered to the one side of the HEPA filter  130  are directly irradiated with UV light from the second light source module  150 . As such, the air purifier has improved sterilization efficiency. In this way, since the microorganisms in the fine dust are removed by sterilizing the HEPA filter  130 , the air purifier  100  can prevent the microorganisms from passing through the HEPA filter  130  and moving together with the air flow. 
     In addition, since the second light source module  150  is disposed to face the one side of the HEPA filter  130 , air is sterilized by UV light emitted from the second light source module  150  during movement of the air between the second light source module  150  and the HEPA filter  130 . As such, the microorganisms are exposed to UV light not only when the microorganisms are attached to one side of the HEPA filter  130  but also when the microorganisms move together with the air. In this manner, the time during which the microorganism are exposed to UV light is increased, thereby improving sterilization efficiency. 
     Accordingly, air having passed through the HEPA filter  130  is an air free from both of fine dust and microorganisms. As such, air flowing into the photocatalytic filter  120  is free from the microorganisms. Since the air free from the microorganisms passes through the photocatalytic filter  120 , the air purifier  100  can prevent the photocatalytic filter  120  from being contaminated by microorganisms in the air. That is, since the air purifier  100  can prevent the photocatalytic filter  120  from being contaminated by air, the air purifier  100  can prevent deterioration in deodorization and sterilization effects with respect to the photocatalytic filter  120 . As a result, it is possible to prevent deterioration in air purification efficiency of the air purifier  100 . 
     The HEPA filter  130  has a structure in which a plurality of filter layers overlap each other. A fraction of UV light emitted from the second light source module  150  passes through a gap between the filter layers of the HEPA filter  130 . The microorganisms may be collected between the filter layers. Here, when UV light emitted from the second light source module  150  passes through the filter layers, the microorganisms collected between the filter layers can be sterilized thereby. In addition, the microorganisms having passed through the HEPA filter  130  together with air can be sterilized through continuous irradiation with UV light emitted from the second light source module  150  and having passed through the HEPA filter  130 . In this manner, sterilization efficiency of the air purifier  100  can be increased through continuous emission of UV light from the second light source module  150 . 
     UV light emitted from the second light source module  150  and having passed through the HEPA filter  130  reaches the photocatalytic filter  120 . Accordingly, the photocatalytic filter  120  is subjected to photocatalytic reaction by the UV light emitted from the first light source module  140  and a fraction of the UV light emitted from the second light source module  150 . That is, since the photocatalytic filter  120  is subjected to photocatalytic reaction with higher intensity of UV light than the intensity of the UV light emitted from the first light source module  140 , the air purifier  100  according to the illustrated exemplary embodiment has improvement in air purification performance. 
     Further, UV light emitted from the second light source module  150  has a shorter wavelength than the UV light emitted from the first light source module  140 . Accordingly, the photocatalytic filter  120  is irradiated not only with the UV light emitted from the first light source module  140  but also with UV light having a shorter wavelength than the UV light emitted from the first light source module  140 . As such, since the photocatalytic filter  120  is irradiated with UV light in a broader wavelength band, photocatalytic reaction on the photocatalytic filter  120  is further activated, thereby improving air purification performance of the air purifier  100 . 
     Further, the air purifier  100  according to the illustrated exemplary embodiment achieves improvement in air purification performance not only through air purification by the photocatalytic filter  120  and the first light source module  140 , but also through sterilization of dusts adhered to the HEPA filter  130 . 
       FIG. 2  and  FIG. 3  are graphs depicting results of an experiment for testing sterilization of a HEPA filter according to exemplary embodiments. 
     The experiment was performed by irradiating the HEPA filter  130 , to which microorganisms adhere in an amount of 107 CFU/ml, with UV light. In this experiment, a light source module including two light sources mounted on a substrate was used. Here, the light source module corresponds to the second light source module shown in  FIG. 1 . Further, an electric current of 20 mA was applied to the light sources. As the microorganisms adhered to the HEPA filter  130 ,  Escherichia coli  was used. 
     Referring to  FIG. 2 , the degree of sterilizing microorganisms was measured in each of four regions C,  1 ,  2 , and  3  from the center of the HEPA filter  130  to one side thereof. 
       FIG. 3  is a graph depicting an experiment result. The abscissa of the graph indicates a UV irradiation time, and the ordinate of the graph indicates the number of microorganisms removed from the HEPA filter. 
     In the graph, the number of microorganisms removed from four regions C, 1, 2, and 3 depending upon UV irradiation time is the same. As such, it could be confirmed that the microorganisms were uniformly sterilized in the four regions. In addition, when the HEPA filter was irradiated with UV light for 10 minutes, the number of microorganisms removed from all of the four regions C, 1, 2, 3 was 7 log CFU/ml. That is, according to this experiment result, when the HEPA filter  130  was sterilized with UV light for 10 minutes, substantially all of the microorganisms adhered to the HEPA filter  130  were removed. Accordingly, when the HEPA filter  130  is sterilized with UV light, air having passed through the HEPA filter  130  may be free from microorganisms. 
       FIG. 4  to  FIG. 11  are schematic views of air purifiers according to second to ninth exemplary embodiments. 
     In descriptions of the air purifiers shown in  FIG. 4  to  FIG. 11 , repeated description of the same components as those of the air purifier  100  of  FIG. 1  will be omitted. 
     Referring to  FIG. 2  to  FIG. 11 , each of air purifiers  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  according to the second to ninth exemplary embodiments includes a body  110 , a photocatalytic filter  120 , a HEPA filter  130 , a first light source module  140 , and a second light source module  150 . 
     The air purifiers  200  to  900  according to the second to ninth embodiments are different from one another in terms of arrangement sequence of the photocatalytic filter  120 , the HEPA filter  130 , the first light source module  140 , and the second light source module  150 . 
     Referring to  FIG. 4 , in the air purifier  200  according to the second exemplary embodiment, the second light source module  150 , the HEPA filter  130 , the photocatalytic filter  120 , and the first light source module  140  are sequentially arranged in the inner space of the body  110  in a direction from the suction port  111  (see  FIG. 1 ) to the discharge port  113  (see  FIG. 1 ). 
     In addition, referring to  FIG. 5 , in the air purifier  300  according to the third exemplary embodiment, the first light source module  140 , the photocatalytic filter  120 , the second light source module  150 , and the HEPA filter  130  are sequentially arranged in the inner space of the body  110  in the direction from the suction port  111  to the discharge port  113 . With this structure, the air purifier sterilizes air in the HEPA filter  130  immediately before discharge of air. Accordingly, the cleanest air can be discharged through the air purifier  300 . 
     Further, referring to  FIG. 6  to  FIG. 10 , in the air purifiers  400  to  800  according to the fourth to eighth exemplary embodiments, the photocatalytic filter  120 , the first light source module  140 , the second light source module  150 , and the HEPA filter  130  are sequentially arranged in the inner space of the body the body  110  in the direction from the suction port  111  (see  FIG. 1 ) to the discharge port  113  (see  FIG. 1 ). Here,  FIG. 8  is a cross-sectional view of the air purifier  600  from one side thereof. 
     Referring to  FIG. 6 , in the air purifier  400  according to the fourth exemplary embodiment, the first light source module  140  and the second light source module  150  are secured to the body  110 , and the first light source module  140  contacts the second light source module  150 . More particularly, a surface of the first light source module  140  opposite to another surface thereof on which the first light source  141  is mounted adjoins a surface of the second light source module  150  opposite to another surface thereof on which the second light source  151  is mounted. 
     Referring to  FIG. 7 , in the air purifier  500  according to the fifth exemplary embodiment, the first light source module  140  and the second light source module  150  are secured to the body  110 , and the first light source module  140  are separated from the second light source module  150 . Here, the first light source module  140  and the second light source module  150  are disposed such that one surface of the first light source module  140  faces one surface of the second light source module  150 . In this manner, the first light source  141  faces the photocatalytic filter  120 , and the second light source  151  faces the HEPA filter  130 . 
     Referring to  FIG. 8 , in the air purifier  600  according to the sixth exemplary embodiment, the first light source module  140  is separated from the second light source module  150  so as not to overlap each other in a diagonal direction. 
     When the first light source module  140  is separated from the second light source module  150 , as shown in  FIG. 7  and  FIG. 8 , air can flow through a gap therebetween. Accordingly, each of the first light source module  140  and the second light source module  150  has an increased contact area with the air, thereby improving heat dissipation. Further, in the air purifier  600  shown in  FIG. 8 , the first light source module  140  is separated from the second light source module  150  in the diagonal direction, which may improve heat dissipation and reliability thereof than the air purifier  500  shown in  FIG. 7 . 
     Referring to  FIG. 9  and  FIG. 10 , in the air purifiers  700 ,  800  according to the seventh and eighth exemplary embodiments, the first light sources  141  and the second light sources  151  are alternately arranged. In addition, the number of first light sources  141  may be different from the number of second light sources  151 . In the seventh exemplary embodiment, the first light source module  140  and the second light source module  150  contact each other. Further, in the eighth exemplary embodiment, the first light source module  140  is separated from the second light source module  150 . 
     When the first light sources  141  are separated from the second light source  151 , the air purifier can prevent heat generated from the first light sources  141  from affecting the second light source  151 . Further, the air purifier can prevent heat generated from the second light source  151  from affecting the first light sources  141 . Thus, with alternate arrangement of the first light sources  141  and the second light sources  151 , the air purifiers  700 ,  800  can have improved reliability. 
     Referring to  FIG. 11 , in the air purifier  900  according to the ninth exemplary embodiment, the first light sources  141  and the second light sources  151  are mounted on a single light source substrate  710 . In this manner, the light source module has a smaller volume than a light source module in which the first light sources  141  and the second light sources  151  are mounted on different light source substrates. Accordingly, air resistance by the light source module is reduced, thereby improving air discharge efficiency. 
       FIG. 12  is a schematic view of an air purifier according to a tenth exemplary embodiment. 
     In description of the air purifier  1000  shown in  FIG. 12 , repeated description of the same components as those of the air purifier  100  of  FIG. 1  will be omitted. 
     The air purifier  1000  according to the tenth exemplary embodiment includes a body  110 , a photocatalytic filter  120 , a HEPA filter  130 , a first light source module  140 , a second light source module  150 , and a prefilter  190 . 
     In the air purifier  1000 , the prefilter  190 , the second light source module  150 , the HEPA filter  130 , the first light source module  140 , and the photocatalytic filter  120  are sequentially arranged in the direction from the suction port  111  to the discharge port  113 . 
     The prefilter  190  may remove large dust particle from air. Accordingly, air having passed through the prefilter  190  is an air free from large dust particles. That is, the prefilter  190  prevents the large dust particle from being attached to the HEPA filter  130  and the photocatalytic filter  120 , thereby preventing reduction in area where the filters react with UV light. Accordingly, efficiency in deodorization and sterilization of the HEPA filter  130  and the photocatalytic filter  120  is improved, thereby improving air purification efficiency of the air purifier  1000 . 
     Referring to  FIG. 12 , the prefilter  190  is disposed adjacent to the suction port  111 . Accordingly, when the dusts flow into the body through the suction port  111 , large particles are removed therefrom while the dusts pass through the prefilter  190 . Then, while air passes through the HEPA filter  130 , fine dusts are removed therefrom. Thereafter, the air having passed through the HEPA filter  130  is purified while passing through the photocatalytic filter  120 . 
     Although the prefilter  190  is illustrated as being disposed between the suction port  111  and the second light source module  150  in  FIG. 12 , the inventive concepts are not limited thereto, and the location of the prefilter  190  may be changed. For example, the prefilter  190  may be disposed at any location so long as the prefilter  190  is disposed between the suction port  111  and the HEPA filter  130 . 
       FIG. 13  to  FIG. 15  are schematic views of an air purifier according to an eleventh exemplary embodiment. 
       FIG. 13  is an exploded perspective view of the air purifier according to the eleventh exemplary embodiment. In addition,  FIG. 14  is a perspective view of the interior of the air purifier according to the eleventh exemplary embodiment. Further,  FIG. 15  is an assembly view of the air purifier according to the eleventh exemplary embodiment. 
     Referring to  FIG. 13  to  FIG. 15 , an air purifier  1100  includes a body  110  and a door  1190  adapted to open/close the body  110 . In addition, the air purifier  1100  includes a fan  180 , a first filter  310 , a second filter  320 , a third filter  330 , a light source module  1140 , a power controller  1150 , and a cover  1160  inside the body  110 . 
     The body  110  is formed with a suction port  111 , a discharge port  113 , a power source  1130 , and a filter replacement portion  1114  on an outer wall thereof. The body  110  may be formed of metal or a resin material, such as a plastic material. Further, the body  110  may be formed in any structure including a rectangular column shape, a circular column shape, or a conical shape, so long as the body has an inner space. 
     Referring to  FIG. 13 , the body  110  is divided into a rear portion and a front portion. The rear portion of the body  110  is formed at both sides thereof with filter guide portions  105  protruding outwardly from an inner wall thereof. Each of the filter guide portions  105  includes a first filter guide  101 , a second filter guide  102 , and a third filter guide  103 . When the front portion of the body  110  is coupled to the rear portion thereof, the first to third filter guides  101  to  103  adjoin ends of first to third filter securing portions  161  to  163  (see  FIG. 14 ), respectively. That is, the first to third filters  310  to  330  are inserted along the first to third filter securing portions  161  to  163  and the first to third filter guides  101  to  103  may be mounted in place. 
     Although not shown in the drawings, a gap is at least partially formed between the inner wall of the rear portion of the body  110  and the filter guide portions  105 . At least one coupling portion  106  of the front portion of the body  110  is coupled to the rear portion of the body  110  in the gap. The front portion of the body  110  may be coupled to the rear portion thereof by any method known in the art, such as screw coupling and the like. 
       FIG. 13  shows the body  110  divided into the front portion and the rear portion, and  FIG. 14  and  FIG. 15  show the body in an assembled state with the front portion thereof coupled to the rear portion thereof. That is, the body  110  is formed by coupling the front portion and the rear portion, which are separately manufactured. However, the inventive concepts are not limited to the body  110  being formed by coupling the front portion to the rear portion. For example, the body  110  may be formed by any methods known in the art so long as the body  110  has a structure capable of receiving various components therein. 
     The suction port  111  refers to an opening through which external air is suctioned into an inner space of the body  110 . In addition, the discharge port  113  refers to an opening through which air is discharged from the interior of the body  110 . That is, polluted air is suctioned into the air purifier  1100  through the suction port  111  and clean air purified inside the air purifier  1100  is discharged through the discharge port  113 . 
     The suction port  111  and the discharge port  113  are formed on different surfaces of the body  110 . For example, referring to  FIG. 13  to  FIG. 15 , the suction port  111  is formed at a lower portion of a rear surface of the body  110  and the discharge port  113  is formed on an upper surface of the body  110 . However, the inventive concepts are not limited thereto, and the locations and structures of the suction port  111  and the discharge port  113  can be variously modified so long as the suction port  111  and the discharge port  113  are formed on different surfaces of the body  110 . 
     An air discharge area of the discharge port  113  may be the same as or different from an air suction area of the suction port  111 . This structure serves to prevent air suctioned into the body  110  from remaining inside the body  110  instead of being discharged through the discharge port  113 . When the air suctioned into the body  110  remains therein instead of being discharged from the body  110 , an eddy current is generated inside the body  110 . The eddy current obstructs the suctioned air from flowing to the discharge port  113 . As such, when discharge flow of sterilized air becomes unsmooth, the air purifier  1100  can suffer from deterioration in purification efficiency, which may increase load in the fan  180  to cause noise. 
     Referring to  FIG. 15 , a periphery of the upper surface of the body  110  having the discharge port  113  formed thereon is surrounded by side surfaces of the body  110 . Such a structure of the body  110  is stronger than a structure of the body having its upper surface coupled to an upper portion of the side surfaces thereof. Accordingly, the upper surface of the body  110  can be prevented from being detached from the side surface thereof from external impact, air pressure, or vibration of the fan  180 . Further, it is possible to prevent noise generation from coupled portions between the surfaces of the body  110  due to vibration of the fan  180 . 
     The power source  1130  is mounted on the inner wall of the body  110 . Here, a portion of the power source  1130  is exposed outside the body  110 . A portion of the power source  1130  is disposed inside the body  110  such that the power source  1130  can be electrically connected to the power controller  1150 . Further, the power source  1130  and the power controller  1150  are disposed to be adjacent to each other at the same location or to contact each other. Referring to  FIG. 13  to  FIG. 15 , the power source  1130  and the power controller  1150  are formed on the rear surface of the body  110  to be placed above the discharge port  113 . However, in some exemplary embodiments, the location of the power source  1130  may be variously modified. 
     The power source  1130  sends a power signal to the power controller  1150  disposed inside the body  110 . The power signal refers to a signal for starting or stopping power supply to the light source module  1140  and the fan  180  through the power controller  1150 . The power source  1130  is connected to the power controller  1150  in a button manner or in an electrostatic manner. The button manner refers to a method of applying a power signal by applying force to the power source  1130  exposed outside the body  110  such that the power source  1130  is physically brought into contact with the power controller  1150 . In addition, the electrostatic manner refers to a method of applying a power signal based on variation in electric current when the body of a user, such as a finger or the like, is brought into contact with the power source  1130  exposed outside the body  110 . The power source  1130  may have any well-known structure and may be formed by any well-known method so long as the power source  1130  can apply a power signal to the power controller  1150 . 
     The filter replacement portion  1114  refers to an opening that connects the interior of the body  110  to an exterior of the body  110 . The filter replacement portion  1114  is an opening through which a filter is attached to the interior of the body  110  or is detached therefrom. Accordingly, the filter replacement portion  1114  is formed to allow the first filter  310 , the second filter  320 , and the third filter  330  to be exposed outside. According to the illustrated exemplary embodiment, the filter replacement portion  1114  allows very easy replacement of the first to third filters  310  to  330  therethrough. The filter replacement portion  1114  may have any structure allowing all of the first to third filters  310  to  330  to be exposed outside such that the first to third filters  310  to  330  can be detachably attached to the body therethrough. 
     Inside the body  110 , the fan  180 , the first filter  310 , the second filter  320 , the third filter  330 , the light source module  1140 , the power controller  1150 , the cover  1160 , and a power connector  1170  are mounted. 
     Referring to  FIG. 13  to  FIG. 15 , the power controller  1150  is disposed inside the body  110 . In addition, the power controller  1150  is disposed near the power source  1130  for electrical connection to the power source  1130 . For example, the power controller  1150  is mounted on the inner wall of the body  110  where the power source  1130  is disposed. The power controller  1150  may be mounted on the inner wall of the body  110  by screw coupling or a bonding agent. The power controller  1150  supplies electric power to the light source module  1140  and the fan  180  in response to a power signal from the power source  1130 . Here, the light source module  1140  emits light and the fan  180  is operated, while power is supplied thereto through the power controller  1150 . The power controller  1150  allows continuous power supply to the light source module  1140 . Further, the power controller  1150  may supply electric power to the light source module  1140  in a pulse driving manner. When the power controller  1150  supplies electric power to the light source module  1140  in the pulse driving manner, light sources  1142  are repeatedly turned on/off. Accordingly, the air purifier  1100  can reduce power consumption, as compared with the structure to which electric power is continuously supplied. 
     In addition, the power controller  1150  may stop power supply to the light source module  1140  and the fan  180  in response to a power signal from the power source  1130  when the light source module  1140  and the fan  180  are supplied with power. In this manner, the power controller  1150  may repeatedly start and stop the power supply in response to a power signal from the power source  1130 . 
     The power controller  1150  is electrically connected to the light source module  1140  and the fan  180  through a cable. Further, the power controller  1150  may be electrically connected to an exterior power supply or an interior power supply through a cable. 
     In the illustrated exemplary embodiment, the power controller  1150  is illustrated as supplying electric power to the light source module  1140  and the fan  180 . However, components receiving electric power supplied from the power controller  1150  are not limited thereto. Alternatively, the power controller  1150  may supply electric power only to the light source module  1140 . Alternatively, the power controller  1150  may be electrically connected not only to the light source module  1140  but also to any components requiring power supply. In addition, the power controller  1150  may supply electric power to other components including the light source module  1140  in the pulse driving manner. Alternatively, the power controller  1150  may supply electric power to the light source module  1140  only in the pulse driving manner while supplying electrical power to other components in a continuous manner. 
     The cover  1160  is mounted on the inner wall of the body  110  and is formed to cover the power controller  1150 . The cover  1160  can protect the power controller  1150  from external impact and can prevent damage thereto due to physical contact with other components. 
     The cover  1160  may be formed at one side thereof with a fan securing portion  610 . The fan securing portion  610  is formed such that a surface of the fan securing portion  610  securing the fan  180  is parallel to the discharge port  113 . Accordingly, the fan  180  mounted on the fan securing portion  610  can be secured inside the body  110 , with the fan  180  disposed in parallel to the discharge port  113 . The fan  180  may be coupled to the fan securing portion  610  by any coupling methods known in the art, such as a bonding agent or screws. 
     When the fan  180  is secured by the fan securing portion  610 , a side surface of the fan  180  may be separated from the inner wall of the body  110 . With this structure, the air purifier  1100  can prevent noise from the fan  180  or other components from leaking outside the air purifier  1100  through a space between the fan  180  and the body  110 . 
     The cover  1160  is formed at the other side thereof with an air flow guide facet  620  having an inclination. The air flow guide facet  620  is tilted between the suction port  111  and the first filter  310 . Referring to  FIG. 13  to  FIG. 15 , the air flow guide facet  620  is tilted to have a gradually increasing height from the suction port  111  toward the first filter  310 . Accordingly, air suctioned into the body  110  through the suction port  111  flows along the air flow guide facet  620  and then passes through the first filter  310 . The air flow guide facet  620  can prevent generation of an eddy current or loss of the suctioned air through the suction port  111  due to collision with the inner wall of the body  110  or other components of the air purifier  1100 . 
     The cover  1160  may include a light source module support  630 . The light source module support  630  is disposed between the fan securing portion  610  and the third filter  330 . The light source module support  630  supports both sides of the light source module  1140  in one direction. For example, the light source module support  630  allows the light source module  1140  to be placed at the center of the third filter  330 . 
     The cover  1160  may be formed with cable passages. The cable passages refer to paths through which cables connecting the components of the air purifier  1100  pass. The locations and the number of cable passages may be varied depending upon arrangement of the components. 
     The fan  180  is mounted on the fan securing portion  610  and is disposed to be parallel to the discharge port  113 . Here, a rotational axis of the fan  180  is perpendicular to the discharge port  113 . For example, the fan  180  is an axial flow fan. 
     The fan  180  allows sterilized air to be discharged from the air purifier  1100  by suctioning the sterilized air from the body  110  and forcing the suctioned air to be discharged through the discharge port  113 . 
     The light source module  1140  includes a light source substrate  1141  and light sources  1142 . The light source substrate  1141  is formed with a circuit configured to receive electric power through the power controller  1150  and to operate the light sources  1142 . The light sources  1142  are disposed on one surface of the light source substrate  1141  and are electrically connected to the light source substrate  1141 . Further, the light source  1142  emits UV light in a sterilization wavelength range and is a spot light source. 
     The light source module  1140  is disposed between the fan  180  and the third filter  330 . One surface of the light source module  1140  having the light sources  1142  mounted thereon faces the third filter  330  and the other surface thereof faces the fan  180 . Accordingly, light emitted from the light sources  1142  can be directed toward the third filter  330  and the light source substrate  1141  can prevent light from being discharged through the fan  180  or the discharge port  113  to the outside. In addition, the light source module  1140  is disposed adjacent to the fan  180  to dissipate heat from the light source module  1140 , whereby the air purifier  1100  can have improved heat dissipation efficiency. 
     The body  110  may have light source module grooves  1115  formed on the inner wall thereof. The light source module grooves  1115  receive both sides of the light source module  1140 . Referring to  FIG. 14 , the light source module grooves  1115  are elongated in one direction. Here, the one direction refers to a direction in which the light source module support  630  is formed. 
     Accordingly, the light source module  1140  is inserted into the light source module grooves  1115  and mounted inside the body  110  while being supported by the light source module support  630 . That is, the light source module  1140  is secured inside the body  110  by being fitted between the inner wall of the body  110  and the light source module support  630 . 
     In the illustrated exemplary embodiment, the light source module  1140  is mounted inside the body  110  by the light source module support  630 . However, the structure for mounting the light source module  1140  is not limited thereto. For example, in some exemplary embodiments, the light source module support  630  may be omitted so long as the light source module grooves  1115  are formed to correspond to both sides of the light source module  1140 . Alternatively, the light source module grooves  1115  may be formed in any structure enabling support of the light source module  1140  in an opposite direction to the light source module support  630 . In this manner, the structures of the light source module grooves  1115  and the light source module support  630  may be variously modified, as needed. 
     In some exemplary embodiments, the light source module  1140  may be disposed so as not to be exposed from the filter replacement portion  1114 . That is, the light source module  1140  may be disposed at a location further indented from one side of the filter replacement portion  1114  toward the fan  180 . With this arrangement, the air purifier  1100  can prevent the light from being discharged to the outside when light is emitted from the light source module  1140 , with the door  1190  open. However, the inventive concepts are not limited to the light source module  1140  from not being exposed through the filter replacement portion  1114 . 
     The first to third filters  310  to  330  are disposed between the light source module  1140  and the suction port  111 . Each of the first to third filters  310  to  330  is formed with a plurality of through holes. The through holes of the first filter  310  have a larger diameter than those of the second filter  320 . For example, the first filter  310  is a prefilter and the second filter  320  is a HEPA filter. In addition, the third filter  330  is a photocatalytic filter performing photocatalytic reaction with light emitted from the light source module  1140 . The through holes of the third filter  330  provided as the photocatalytic filter have a rectangular cross-section. The photocatalytic filter including the through holes each having a rectangular cross-section can be more easily manufactured than a typical photocatalytic filter including through holes each having a honeycomb-shaped cross-section. 
     Referring to  FIG. 13  to  FIG. 15 , the first to third filters  310  to  330  are disposed to block an air passage between the cover  1160  and the inner wall of the body  110 . That is, one of side surfaces of the first to third filters  310  to  330  closely contacts the cover  1160  and the other side surfaces thereof closely contact the inner wall of the body  110 . Accordingly, air suctioned through the suction port  111  is required to pass through the through holes of the first to third filters  310  to  330  in order to escape through the discharge port  113 . 
     The first to third filters  310  to  330  are disposed in the sequence of the first filter  310 , the second filter  320 , and the third filter  330  with reference to the suction port  111 . 
     The first filter  310  acting as the prefilter serves to filter large dust particles moving together with air. 
     The second filter  320  acting as the HEPA filter serves to filter fine dusts having passed through the first filter  310 . The second filter  320  prevents the fine dusts from contacting the third filter  330  or from being accumulated thereon. When the fine dusts are accumulated on the third filter  330 , a contact area between light emitted from the light sources  1142  and the third filter  330  is reduced. As such, the second filter  320  can prevent deterioration in sterilization of air by the third filter  330  by filtering the fine dusts. 
     The third filter  330  acting as the photocatalytic filter serves to sterilize air passing therethrough from reaction with light emitted from the light sources  1142 . In this manner, the air purifier  1100  can perform removal of large dust particles and fine dusts and sterilization of air at the same time using the first to third filters  310  to  330 . 
     According to the exemplary embodiments, a distance between the third filter  330  and the light source  1142  is greater than or equal to a value represented by Equation: the area of the third filter/[2×tan(angle of light beam/2)×0.2] and smaller than or equal to a value represented by Equation: the area of the third filter/[2×tan(angle of light beam/2)×2]. Here, the area of the third filter refers to an area of a surface of the third filter  330  facing the light source  1142 . 
     If the distance between the third filter  330  and the light source  1142  is smaller than the value represented by Equation: the area of the third filter/[2×tan(angle of light beam/2)×0.2], the distance between the third filter  330  and the light source  1142  is too narrow, thereby making it difficult to uniformly irradiate the entirety of the third filter  330 . Accordingly, in order to allow the entirety of the third filter  330  to be uniformly irradiated with light, the air purifier  1100  requires a plurality of light sources, which increases manufacturing costs. 
     If the distance between the third filter  330  and the light source  1142  is greater than the value represented by Equation: the area of the third filter/[2×tan(angle of light beam/2)×2], the distance between the third filter  330  and the light source  1142  increases, thereby causing reduction in light intensity. As a result, efficiency in photocatalytic reaction is reduced. 
     The air purifier  1100  according to the illustrated exemplary embodiment maintains a suitable distance between the light sources  1142  and the third filter  330 , thereby enabling efficient air purification. 
     In some exemplary embodiments, the air purifier  1100  may be provided with a carbon filter to remove odor. That is, the filters provided to the air purifier  1100  are not limited to the aforementioned filters. The air purifier  1100  may be modified into any structure so long as the air purifier  1100  includes the photocatalytic filter and at least one of the HEPA filter, the prefilter, and the carbon filter therein. 
     The body  110  is formed on the inner wall thereof with a first filter securing portion  161 , a second filter securing portion  162 , and a third filter securing portion  163 . The first to third filters  310  to  330  are secured inside the body  110  by inserting side surfaces of the first to third filters  310  to  330  into the first filter securing portion  161  to the third filter securing portion  163 , respectively. 
     The body  110  may further include a power connector  1170  disposed therein. The power connector  1170  allows electric power from an exterior power supply to be supplied to the power controller  1150 . 
     In addition, both the inner wall of the body  110  and the cover  1160  have a black color. 
     The door  1190  is formed to cover the filter replacement portion  1114  of the body  110 . The filter replacement portion  1114  of the body  110  is opened and closed according to opening/closing movement of the door  1190 .  FIG. 13  to  FIG. 15  shows that the door  1190  is opened when the door  1190  is completely separated from the body  110 . When the door  1190  is opened, the first filter  310 , the second filter  320 , and the third filter  330  are exposed to the outside through the filter replacement portion  1114 . The door  1190  completely separated from the body  110  is closed by coupling the door  1190  to the body  110  in a sliding manner. The door  1190  is detachably attached to the body  110  while moving from the front side of the body  110  toward the rear side thereof. The door  1190  is formed with door guides  910  for opening and closing the body  110 . The door guides  910  are formed at both sides of the door  1190  to continuously protrude from an inner wall of the door  1190 . Further, the body  110  is formed with door guide grooves  1117  on an outer wall thereof at both sides thereof. The door guide grooves  1117  are formed where the door guides  910  are brought into contact with the door guide grooves  1117 , and have a groove structure to receive the door guides  910  inserted into the door guide grooves  1117 . According, the door  1190  is coupled to the body  110  by inserting the door guides  910  into the door guide grooves  1117 . Here, each of the door guides  910  may be formed with a door securing portion  911  having a protruding structure. Further, each of the door guide grooves  1117  may be formed with a door securing groove  171  corresponding to the door securing portion  911 . When the door  1190  is brought into complete contact with the body  110 , the door securing portions  911  are inserted into the door securing grooves  171  so that the door  1190  can be secured to the body  110 . The door securing portion  911  and the door securing groove  171  will be described in more detail below where the door  1190  is coupled to the body  110 . 
     Conventionally, the body of the air purifier is required to be completely disassembled for replacement of filters. Otherwise, it is necessary to replace the entire air purifier. However, the air purifier  1100  according to the illustrated exemplary embodiment allows replacement of filters only through separation of the door  1190 . Accordingly, it is possible to reduce time and cost for replacement of the filters. 
     The following drawings are briefly shown for convenience of description and understanding. For structures of components omitted in the following drawings may be found above with reference to  FIG. 13  to  FIG. 15 . 
       FIG. 16  is a schematic view of an air purifier according to a twelfth exemplary embodiment. 
     In descriptions of an air purifier  1200  according to the twelfth exemplary embodiment, repeated description of the same components as those of the air purifier  1100  of  FIG. 15  will be omitted to avoid redundancy. 
     Referring to  FIG. 16 , the air purifier  1200  includes a power storage  510  received therein. The power storage  510  is disposed inside the body  110  and is electrically connected to the power controller  1150 . The power controller  1150  supplies electric power stored in the power storage  510  to the fan  180  and the light source module  1140  in response to a power signal from the power source  1130  (see  FIG. 13 ). 
     According to the illustrated exemplary embodiment, when electric power stored in the power storage  510  in the air purifier  1200  is completely consumed, the power storage  510  may be replaced by another power storage  510 . Alternatively when electric power stored in the power storage  510  is completely consumed, the power storage  510  may be connected to an external power supply to be charged with power. For example, the power storage  510  may be a consumable battery or a rechargeable battery. 
     When the air purifier  1200  receives the power storage  510  therein, the air purifier  1200  does not require continuous connection to an external power supply. Accordingly, since the air purifier  1200  is not required to be continuously connected to the external power supply through a cable  960 , the air purifier  1200  reduces spatial restriction for installation of the air purifier  1200 . 
       FIG. 17  and  FIG. 18  are schematic views of air purifiers according to thirteenth and fourteenth exemplary embodiments. 
     In descriptions of air purifiers  3000 ,  4000  according to the thirteenth and fourteenth exemplary embodiments, repeated description of the same components as those of the air purifier  1100  of  FIG. 15  will be omitted. 
     Referring to  FIG. 17  and  FIG. 18 , each of the air purifiers  3000 ,  4000  according to the thirteenth and fourteenth exemplary embodiments includes a preliminary power storage  520  inside the body. Referring to the drawings, the power controller  1150  is connected to the preliminary power storage  520  and an external power supply. 
     In the air purifier  1300  according to the thirteenth exemplary embodiment, the power controller  1150  receives electric power supplied from the external power supply. However, when the power controller  1150  cannot receive electric power from the power supply due to failure of the cable  960  or the like, the power controller  1150  may receive electric power supplied from the preliminary power storage  520 . The preliminary power storage  520  may be selected from any devices capable of preliminarily storing electric power. For example, the preliminary power storage  520  may be a rechargeable battery. The power controller  1150  is connected to the preliminary power storage  520  and a power connector  1170  connected to the external power source through the cables  960 . 
     In  FIG. 17 , the power controller  1150  is illustrated as being connected to the preliminary power storage  520  and the power connector  1170  connected to the external power source via the separate cables  960 . However, in the air purifier  1400  according to the fourteenth exemplary embodiment shown in  FIG. 18 , the power controller  1150  may be connected to the preliminary power storage  520 , which is connected to the external power supply. In the illustrated exemplary embodiment, the power controller  1150  is connected to the preliminary power storage  520  through a cable  960  and is also connected to the external power supply through another cable  960 . In this structure, the preliminary power storage  520  may supply some of electric power supplied from the external power supply to the power controller  1150  and may store (charge) the remaining electric power as preliminary electric power. 
       FIG. 19  is a schematic view of an air purifier according to a fifteenth exemplary embodiment. 
     In descriptions of an air purifier  1500  according to the fifteenth exemplary embodiment, repeated descriptions of the same components as those of the air purifiers according to the eleventh to fourteenth exemplary embodiments will be omitted. 
     Referring to  FIG. 19 , the air purifier  1500  includes an input unit  182  and an output unit  181 . 
     The input unit  182  and the output unit  181  are formed on the outer wall of the body  110 . The output unit  181  visually represents information about the air purifier  1500  and information input through the input unit  182 . For example, the output unit  181  may be a liquid crystal display (LED) and the input unit  182  may be a touch pad. However the types of the output unit  181  and the input unit  182  are not limited thereto, and any display device and input device applicable to an air purifier may be used. 
     When information such as a filter replacement date is input through the input unit  182 , the information input to the output unit  181  is displayed thereon. A user can determine a filter replacement time based on the information displayed on the output unit  181 . In addition, a message may be input through the input unit  182  and a message input to the output unit  181  may be displayed thereon. With such a function, another user can check the message of the user. In addition, the output unit  181  may display information, such as date, time, and the like. 
     In the illustrated exemplary embodiment, the input unit  182  and the output unit  181  are illustrated as separate components. However, the input unit and the output unit  181  may be formed as a single component capable of performing both input and output, such as a touchscreen. 
       FIG. 20  is a schematic view of an air purifier according to a sixteenth exemplary embodiment. 
     In descriptions of an air purifier  1600  according to the sixteenth exemplary embodiment, repeated description of the same components as those of the air purifiers according to the eleventh to fifteenth exemplary embodiments will be omitted. 
     Referring to  FIG. 20 , the air purifier  1600  according to the sixteenth exemplary embodiment includes a photo sensor  810 . 
     The photo sensor  810  detects the intensity of light reflected from the first to third filters  310  to  330 . As the amount of dust attached to the first to third filters  310  to  330  increases, the intensity of light reflected from the first to third filters  310  to  330  decreases. 
     The photo sensor  810  may compare the intensity of detected light with a predetermined reference value. As a result of comparison, if the intensity of the light is smaller than the predetermined reference value, the photo sensor  810  transmits a filter replacement signal to the output unit  181  (see  FIG. 19 ). In response to the filter replacement signal from the photo sensor  810 , the output unit  181  (see  FIG. 19 ) outputs a filter replacement alarm to inform a user of a filter replacement time. 
     The output unit  181  may have the same configuration as the output unit  181  (see  FIG. 19 ) according to the fifteenth exemplary embodiment. The output unit  181  may be a speaker configured to output sound or a light emitting device configured to emit light having a color. Further, the output unit  181  may include at least two of devices outputting text, light, and sound. Thus, the output unit  181  may output a filter replacement alarm including at least one of text, light, and sound to the outside. 
     In  FIG. 20 , the photo sensor  810  is disposed to detect the intensity of light reflected from the third filter  330 . Alternatively, the air purifier  1600  may include a plurality of photo sensors  810  to detect the intensity of light reflected from each of the first to third filters  310  to  330 . In this structure, each of the plural photo sensors  810  generates and sends a filter replacement signal to the output unit  181  (see  FIG. 19 ). The output unit  181  (see  FIG. 19 ) may output a filter replacement alarm with respect to each of the first to third filters  310  to  330  in response to the filter replacement signal from the photo sensor  810 . Accordingly, the air purifier  1600  according to the illustrated exemplary embodiment enables replacement of a filter requiring replacement instead of replacing all of the first to third filters  310  to  330 . 
       FIG. 21  is a schematic view of an air purifier according to a seventeenth exemplary embodiment. 
     In descriptions of an air purifier  1700  according to the seventeenth exemplary embodiment, repeated description of the same components as those of the air purifiers according to the eleventh to sixteenth exemplary embodiments will be omitted. 
     Referring to  FIG. 21 , the air purifier  1700  according to the seventeenth exemplary embodiment includes a door sensor  820 . 
     The door sensor  820  detects whether the door  1190  is open or closed. When the door  1190  is open, the filter replacement portion  1114  of the body  110  is exposed to the outside. When the door  1190  is closed, the door  1190  closely contacts the body  110  to close the filter replacement portion  1114 . 
     For example, the door sensor  820  is a magnetic sensor, and magnet switches  821 ,  822  may be provided to the door  1190  and the body  110 , respectively. When the door  1190  is open, the magnet switches  821 ,  822  provided to the door  1190  and the body  110  are separated from each other. In addition, when the door  1190  is closed, the magnet switches  821 ,  822  provided to the door  1190  and the body  110  adjoin each other. The door sensor  820  may detect opening or closing of the door  1190  based on whether the magnet switches  821 ,  822  adjoin each other. 
     Although the door sensor  820  is illustrated as a magnetic sensor in the illustrated exemplary embodiment, the type of the door sensor  820  is not limited thereto. According to an exemplary embodiment, the door sensor  820  may be selected from any kind of sensor capable of detecting whether the door  1190  is open or closed. 
     In addition, according to the illustrated exemplary embodiment, the door sensor  820  may be connected to the power controller  1150  (see  FIG. 13 ). For example, the door sensor  820  may send door-open and door-closed signals to the power controller  1150  (see  FIG. 13 ) depending upon whether the door  1190  is open or closed. The power controller  1150  (see  FIG. 13 ) stops power supply to the light source module  1140  and the fan  180  in response to the door-open signal. 
     The power controller  1150  (see  FIG. 13 ) starts power supply to the light source module  1140  and the fan  180  in response to the door-closed signal from the door sensor  820 . 
     Alternatively, the power controller  1150  (see  FIG. 13 ) may start power supply to the light source module  1140  and the fan  180  only in response to both a power signal from the power source  1130  and the door-closed signal from the door sensor  820 . 
     According to the illustrated exemplary embodiment, the door sensor  820  may send the door-open signal and the door-closed signal to the output unit  181 . The output unit  181  may output a door-open alarm and a door-closed alarm in response to the door-open signal and the door-closed signal. 
       FIG. 22  is a schematic view of an air purifier according to an eighteenth exemplary embodiment. 
     An air purifier  1800  according to the eighteenth exemplary embodiment has the same components excluding first to third filters  310  to  330  as those of the air purifiers according to the eleventh to seventeenth exemplary embodiments. Accordingly, illustration of the other components excluding the first to third filters  310  to  330  is omitted. Descriptions of the components omitted below are described above with reference to the air purifiers according to the eleventh to seventeenth exemplary embodiments. 
     Referring to  FIG. 22 , the first to third filters  310  to  330  are provided with first to third resilient frames  311  to  331 , respectively. 
     The first to third resilient frames  311  to  331  are formed of a resilient material. For example, the first to third resilient frames  311  to  331  may be formed of rubber or a porous material, such as a sponge. 
     The first resilient frame  311  is mounted on the first filter  310  to surround an outer surface of the first filter  310 . The second resilient frame  321  is mounted on the second filter  320  to surround an outer surface of the second filter  320 . The third resilient frame  331  is mounted on the third filter  330  to surround an outer surface of the third filter  330 . 
     The first to third resilient frames  311  to  331  enable easy detachment or attachment of the first to third filters  310  to  330  to the interior of the body  110 . The third filter  330  acting as a photocatalytic filter is formed of a rigid material, such as a ceramic material, and does not allow easy insertion into the body  110 . However, according to the illustrated exemplary embodiment, although the third filter  330  is rigid, the third resilient frame  331  is compressed by external force to allow the third filter  330  to be easily inserted into the body  110  due to elasticity of the third resilient frame  331 . 
     In this manner, the first filter  310  and the second filter  320  can also be easily inserted into the body  110  by the first resilient frame  311  and the second resilient frame  321  mounted thereon. 
     Although the first to third resilient frames  311  to  331  are illustrated as being mounted on the first to third filters  310  to  330 , respectively, the inventive concepts are not limited thereto. For example, when the filters are formed to have elasticity, the resilient frames may be omitted. More particularly, when the first filter  310  and the second filter  320  have elasticity, the third resilient frame  331  may be provided only to the third filter  330 . 
       FIG. 23  is a schematic view of an air purifier according to a nineteenth exemplary embodiment. 
     In descriptions of an air purifier  1900  according to the nineteenth exemplary embodiment, repeated description of the same components as those of the air purifiers according to the eleventh to eighteenth exemplary embodiments will be omitted. 
     Referring to  FIG. 23 , the air purifier  1900  is provided with springs  191  for easy detachment and attachment of the first to third filters  310  to  330 . In  FIG. 23 , the first filter  310  and the second filter  320  shown in  FIGS. 13 to 22  are not shown. According to the illustrated exemplary embodiment, each of the springs  191  is provided to a portion of the cover  1160  where each of the first to third filters  310  to  330  is mounted. 
     In addition, the body  110  is provided with stoppers  195 . The stoppers  195  protrude from both sides of the filter replacement portion  1114 , such that the first to third filters  310  to  330  are placed inside the body  110 . The stoppers  195  are formed at an inlet side of the filter replacement portion  1114  of the body  110 . For example, the stoppers  195  may be formed on the first to third filter securing portions  161  to  163  at the inlet side of the filter replacement portion  1114 . The first to third filters  310  to  330  are inserted into the body  110  to be disposed at predetermined locations inside the body  110  while compressing the spring  191 . When force applied to the spring  191  is removed, the stoppers  195  prevent the first to third filters  310  to  330  from escaping from the body  110  by elastic force of the spring  191 . Further, the first to third filters  310  to  330  may be secured at predetermined locations by elastic force of the spring  191  and the stoppers  195 . In addition, the spring  191  and the stoppers  195  may be formed to allow mounting of only at least one of the first to third filters  310  to  330 . 
     For example, the first filter  310  and the second filter  320  may be formed of an elastic material and the third filter  330  may be formed of an inelastic material. Here, the first filter  310  and the second filter  320  are inserted into the first filter securing portion  161  and the second filter securing portion  162  to be secured inside the body  110  by elastic force thereof, as in the eleventh exemplary embodiment. The third filter  330  having no elasticity may be secured inside the body  110  by the spring  191  and the stoppers  195 . In this manner, the locations and the number of the springs  191  and the stoppers  195  may be variously modified, as needed. 
       FIG. 24  and  FIG. 25  are schematic views of air purifiers according to twentieth and twenty first exemplary embodiments. 
     In descriptions of air purifiers  2000 ,  2100  according to the twentieth and twenty first exemplary embodiments, repeated descriptions of the same components as those of the air purifiers according to the eleventh to twentieth exemplary embodiments will be omitted. 
     According to the illustrated exemplary embodiment, the door  1190  is formed to surround both sides of the body  110  and the filter replacement portion  1114 . With this structure, the door  1190  is opened or closed, with a portion of the door  1190  connected to the body  110 . Referring to  FIG. 24  and  FIG. 25 , a lower end of the door  1190  is connected to the body  110 . Accordingly, with the lower end of the door  1190  secured to the body  110 , the door  1190  is opened or closed by detaching or attaching an upper end and a side surface of the door  1190  to the body  110 . 
       FIG. 24  shows the filter replacement portion  1114  formed to expose only the first to third filters  310  to  330 , and  FIG. 25  shows the filter replacement portion  1114  formed to expose not only the first to third filters  310  to  330  but also the fan  180 . The structure of the door  1190  may be changed depending upon the size of the filter replacement portion  1114  so as to open or close the filter replacement portion  1114 . 
     The door  1190  is formed at both sides thereof with door guides  910  extending in a direction of being coupled to the body  110  on the side surfaces of the door  1190 . Each of the door guides  910  is formed at one end thereof with a door securing portion  911  protruding outward from the door guide  910 . 
     The body  110  is formed with door guide grooves  1171  on an outer wall thereof so as to correspond to the door guides  910 , respectively. Each of the door guide grooves  1171  of the body  110  is formed at one end thereof with a door securing groove  171 . 
     The door securing groove  171  is covered by the outer wall of the body  110  excluding an inlet thereof connected to the door guide groove  1171 . A door securing portion  911  is formed to pass through a gap between the outer wall of the body  110  and the inlet of the door securing groove  171 . 
     The door securing groove  171  is formed to allow the door securing portion  911  to be inserted into the door securing groove  171  when force is applied to both sides of the door  1190  and to allow the door securing portion  911  to be caught by the outer wall of the body  110  upon removal of force therefrom. 
     That is, when the door  1190  is coupled to the body  110 , the door guides  910  are inserted into the door guide grooves  1171 , and the door securing portions  911  are inserted into the door securing grooves  171 . Then, the door securing portions  911  are secured to the door securing grooves  171  by being blocked by the outer wall of the body  110  due to the protruding structure thereof. As a result, the door  1190  is in a closed state to cover the filter replacement portion  1114 . 
     When the door  1190  is in the closed state, the door securing portions  911  are forced to pass through a gap between the outer wall of the body  110  and the door securing grooves  171  by applying force to both sides of the door  1190  such that the door  1190  can be opened. 
     The door securing portions  911  may be further formed on the inner wall of the door  1190  at an upper portion thereof, and the door securing grooves  171  may also be further formed on the body  110  at locations corresponding to the door securing portions  911 . 
     Referring to  FIG. 25 , the body  110  is formed such that the side surfaces of the body  110  surround the periphery of the upper surface of the body  110  having the discharge port  113  formed thereon. That is, the periphery of the upper surface of the body  110  is surrounded by the side surfaces thereof. When the door  1190  is closed, an upper portion of the door  1190  also surrounds the periphery of the upper surface of the body  110 . For example, when the upper surface of the body  110  is disposed on the side surfaces thereof to be secured thereby, the upper portion of the door  1190  is also disposed under the upper surface of the body  110  when the door  1190  is closed. In addition, an upper end of the door  1190  is brought into close contact with the inner surface of the upper surface of the body  110  and moves along a curved line upon opening and closing the door  1190 . Accordingly, when the door  1190  is opened or closed, friction occurs between the upper end of the door  1190  and the inner wall of the upper surface of the body  110 . As a result, the door  1190  cannot be easily opened or closed and the body  110  can be damaged. 
     However, when the periphery of the upper surface of the body  110  is surrounded by the side surfaces of the body  110  as in the illustrated exemplary embodiment, friction does not occur between the door  1190  and the upper surface of the body  110 , and the body  110  can be prevented from being damaged. 
       FIG. 26  is a schematic view of an air purifier according to a twenty second exemplary embodiment. 
     In descriptions of an air purifier  2200  according to the twenty second exemplary embodiment, repeated descriptions of the same components as those of the air purifiers according to the eleventh to twenty first exemplary embodiments will be omitted. 
     According to the illustrated exemplary embodiment, the door  1190  is formed to cover a surface of the body  110  on which the filter replacement portion  1114  is formed. 
     In the twenty second exemplary embodiment, the door  1190  is formed to cover one surface of the body on which the filter replacement portion  1114  is formed. 
     According to the illustrated exemplary embodiment, an upper outer wall of the door  1190  is formed with a door button  920 . In addition, the door  1190  is formed with a door securing portion  915  on an upper inner wall thereof, and the body  110  is formed with a door securing groove  175  at a location thereof corresponding to the door securing portion  915 . 
     The door securing portion  915  is physically or electrically connected to the door button  920 . Accordingly, when the door button  920  is pushed or touched, the door securing portion  915  may protrude outwards from the door  1190  or may be inserted into the door  1190 . 
     For example, with the door securing portion  915  inserted into the door  1190 , the door  1190  is brought into close contact with the body  110 . When the door button  920  is operated in this state, the door securing portion  915  protrudes outwards from the door  1190 , the door securing portion  915  is inserted into the door securing groove  175  of the body  110 . As a result, the door  1190  is in a closed state wherein the door  1190  is secured to the body  110 . In addition, when the door button  920  is operated with the door  1190  secured to the body  110 , the door securing portion  915  is inserted into the door  1190 . As a result, the door  1190  is opened to be detached from the body  110 . 
       FIG. 27  is a schematic view of an air purifier according to a twenty third exemplary embodiment. 
     In descriptions of an air purifier  2300  according to the twenty third exemplary embodiment, repeated descriptions of the same components as those of the air purifiers according to the eleventh to twenty second exemplary embodiments will be omitted. 
     Referring to  FIG. 27 , the door  1190  is formed to cover only one surface of the body  110  as shown in  FIG. 26 . 
     According to the illustrated exemplary embodiment, a portion of the door  1190  is formed with a magnetic component. For example, a gasket  930  may be mounted along the periphery of the door  1190 . Further, the door  1190  is provided with a sensor or a switch. 
     The body  110  is provided with an electromagnet  940 . The electromagnet  940  is mounted on a portion of the body  110  contacting the gasket  930  of the door  1190 . 
     For example, when the door  1190  is brought into close contact with the body  110 , attractive force is generated between the gasket  930  of the door  1190  and the electromagnet  940  of the body  110 . As a result, the door  1190  is secured to the body  110  in a closely contacting state by the attractive force therebetween, whereby the door  1190  is closed. When a signal is applied to the sensor or the switch by applying force to the door  1190  brought into close contact with the body  110 , electric current is supplied to the electromagnet  940 . Accordingly, the electromagnet  940  exhibits polarity, thereby generating repulsive force between the electromagnet  940  and the gasket  930 . As a result, the door  1190  and the body  110  are pushed away from each other by the repulsive force, whereby the door  1190  is opened. 
     With the electromagnet  940  and the gasket  930 , the air purifier  2300  enables easy opening and closing of the door  1190 . 
     Herein, various structures for opening and closing the door  1190  through the structures of the door  1190  and the body  110  are described. However, the inventive concepts are not limited to the aforementioned structures for opening and closing the door  1190 . The structure for opening and closing the door  1190  may be variously modified as needed. 
       FIG. 28  is a schematic view of an air purifier according to a twenty fourth exemplary embodiment. 
     In descriptions of an air purifier  2400  according to the twenty fourth exemplary embodiment, repeated descriptions of the same components as those of the air purifiers according to the eleventh to twenty fourth exemplary embodiments will be omitted. 
     Referring to  FIG. 28 , the air purifier  2400  may include a support  950 . The support  950  is formed on one surface of the outer wall of the body  110 . 
     The support  950  is formed to separate a lower surface of the body  110  of the air purifier  2400  from the floor of an installation space of the air purifier  2400 . Accordingly, the power source  1130  may be formed at any location of the body  110 . For example, even when the power source  1130  is formed on the lower surface of the body  110 , since the power source  1130  is separated from the floor of the installation space of the air purifier  2400 , the power source  1130  can be prevented from malfunctioning due to contact with the floor of the installation space. 
     In addition, the support  950  may provide an increased degree of design freedom for the suction port. For example, since the lower surface of the body  110  is spaced apart from the floor of the installation space by the support  950 , the suction port may also be formed on the lower surface of the body  110 . When the suction port is formed on the lower surface of the body  110 , an air passage is formed from the suction port to the first to third filters, the fan and the discharge port in one direction. With the air passage formed in one direction, air loss inside the air purifier  2400  can be reduced, thereby improving air purification efficiency. 
     Although some exemplary embodiments have been described herein, it should be understood that these exemplary embodiments are provided for illustration only and are not to be construed in any way as limiting the exemplary embodiment of the disclosure, and that various modifications, changes, alterations, and equivalent embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention.