Patent Publication Number: US-2023135133-A1

Title: Mask

Description:
TECHNICAL FIELD 
     The following description relates to a mask having a fan, and more particularly to a mask having an air purifying module for uniformly passing air through a filter. 
     BACKGROUND ART 
     Air pollution increases due to rapid industrialization and increased exhaust gas emissions from vehicles and the like. Pollutants (hereinafter referred to as foreign matter) causing such air pollution may lead to respiratory and heart diseases. 
     Particularly, fine dust and yellow dust, penetrating into the respiratory system of the human body and causing various diseases and the like, have a fatal adverse effect on people&#39;s lives today. 
     The fine dust is invisibly thin and tiny dust, and contains sulfur dioxide, nitrogen oxide, lead, ozone, carbon monoxide, and the like, as well as various air pollutants. Causes of the emissions may be divided into artificial emissions from vehicles or factories, and natural emissions from yellow dust caused by sandstorms, or dust caused by volcanic ash, forest fire, and the like. When inhaled by people, the fine dust penetrates deep into pulmonary alveoli, to cause various respiratory diseases, asthma, headache, atopy, etc., and particularly when inhaled continuously by the old and the infirm, the fine dust may lower their immune function, leading to death from lung diseases. 
     For this reason, there has been an increasing demand recently for protective equipment (e.g., medical mask) for filtering out foreign matter from the air. Such protective equipment generally includes a mask main body, a filter accommodated in the mask main body and covering the mouth and nose, and ear loops provided for the mask main body. By wearing the protective equipment, a user may protect the respiratory system from foreign matter in the air. 
     In a general case, as a filter performance for filtering out foreign matter is improved, a greater lung capacity is required for breathing. Accordingly, a problem occurs in that inconvenience of a mask wearer&#39;s breathing is caused in proportion to the filter performance for filtering out foreign matter. 
     In order to solve the above problem, Korean Registered Patent No. 10-1783804 (registered on Sep. 26, 2017) discloses a “mask with an air purifying filter device attached thereto,” which includes a mask main body, a filter accommodated in the mask main body, and a blower fan allowing air to flow into the mask main body. 
     However, the mask disclosed in the related art has a problem in that an air volume of the blower fan decreases due to resistance of the filter. As a method to overcome such problem, masks that are currently available in the market suggest a method of rotating a fan at a high RPM or a method of applying a porous passage or increasing a suction area to optimize the passage. 
     However, if the fan rotates at a high RPM while a gap between the fan and the filter is narrowed to reduce the volume of the mask, a problem occurs in that the entire area of the filter may not be used efficiently due to a non-uniform air flow. It is inefficient in that the flow is concentrated at an end portion of the fan, such that the edge of the filter is intensively used. 
     Furthermore, several problems also occur even when a guide vane  11  of  FIG.  1 A  or a porous passage  12  of  FIG.  1 B  is applied in order to optimize the passage. First, in the case of the porous passage  12 , turbulence noise may be generated due to a non-uniform suction flow. Further, as air is introduced through a large number of holes, the inflow of air is limited. In the case where a suction area is increased using the guide vane  11 , a flow rate may increase, but noise reduction effect may not be produced as the suction area is expanded. 
     Accordingly, there is a need to develop a mask allowing a uniform suction flow through a fan, without applying the guide vane  11  or the porous passage  12 . 
     PRIOR ART DOCUMENT 
     Patent Document 
     Korean Registered Patent No. 10-1783804 (Sep. 26, 2017) 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     It is an object of the present disclosure to provide a mask generating a uniform suction flow even when a fan rotates at a high rpm. 
     In addition, it is another object of the present disclosure to provide a mask having a fan but having a reduced volume. 
     Further, it is yet another object of the present disclosure to provide a mask having a fan but generating less noise. 
     The objects of the present disclosure are not limited to the aforementioned objects, and other objects not described herein will be clearly understood by those skilled in the art from the following description. 
     Solution to Problem 
     In accordance with an aspect of the present disclosure, the above and other objects can be accomplished by providing a mask, including: a mask main body forming an internal space for receiving air in front of a nose and a mouth of the user, and having an inlet providing a passage for outside air to flow into the internal space; and an air purifying module mounted in the mask main body, and having a first passage for allowing the outside air to flow in a direction perpendicular to a side surface of the air purifying module. 
     Further, the mask according to the present disclosure may include the air purifying module, including: a case forming an exterior of the air purifying module; a cover covering a portion of the case; a filter disposed inside the case and filtering air introduced from an outside; and a fan disposed inside the case and provided on an inside of the filter. 
     The case may include a connection part inclined downwardly toward a center line of the mask main body from one surface of the case, and connected to the inlet of the mask main body. 
     The connection part may have a second passage formed therein, through which the outside air having passed through the filter and the fan may flow into the internal space. 
     The cover may include a curved surface portion having a convex curvature outwardly of the cover, wherein a distance between the cover and the filter may be largest at a center of the curved surface portion. 
     An air pocket may be formed between the curved surface portion and the filter, the air pocket being formed as a space for the outside air introduced through the first passage to flow along the curved surface portion. 
     In addition, the cover may include a flat surface portion extending in a direction parallel to the filter from an edge of the curved surface portion, and may further include a protrusion protruding inwardly of the cover from the flat surface portion, and coupled to the case to fix the cover. 
     A first direction length of the protrusion may be shorter than a first direction length of the cover. 
     Further, the case may include a recess receiving the protrusion, wherein a second direction length of the protrusion may be longer than a depth of the recess. 
     In accordance with another aspect of the present disclosure, the above and other objects can be accomplished by providing a mask, including: a mask main body forming an internal space for receiving air in front of a nose and a mouth of the user, and having a first inlet and a second inlet providing passages for outside air to flow into the internal space; a first air purifying module mounted on one side of the mask main body, and having a la passage for allowing the outside air to flow in a direction perpendicular to a side surface of the air purifying module; and a second air purifying module mounted on the other side of the mask main body, and having a  1   b  passage for allowing the outside air to flow in a direction perpendicular to a side surface of the air purifying module. 
     In addition, the mask according to the present disclosure may include the second air purifying module which is bilaterally symmetrical to the first air purifying module with respect to a center line of the mask main body. 
     Other detailed matters of the exemplary embodiments are included in the detailed description and the drawings. 
     Advantageous Effects of Invention 
     The mask according to the present disclosure has one or more of the following effects. 
     First, as air is sucked through the first passage formed in a direction perpendicular to a side surface, noise caused when the air is sucked may be reduced. 
     Second, a cover has a curved surface portion such that an air pocket, formed as a space for an air flow, may be formed between the cover and the filter, thereby allowing a uniform flow of the sucked air. 
     Third, by overcoming a non-uniform suction flow, pressure between the cover and the filter may be reduced. 
     Fourth, as a result, an area of the filter may be used efficiently, thereby improving durability of the filter. 
     Fifth, even when a thin fan is used, the fan may rotate at a high rpm, such that a volume of the air purifying module may be reduced. 
     The effects of the present disclosure are not limited to the aforesaid, and other effects not described herein will be clearly understood by those skilled in the art from the following description of the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS.  1 A and  1 B  are diagrams illustrating a general mask. 
         FIG.  2    is a diagram illustrating a mask according to an embodiment of the present disclosure. 
         FIG.  3    is a diagram illustrating a mask main body according to an embodiment of the present disclosure. 
         FIG.  4    is a cross-sectional view of an air purifying module according to an embodiment of the present disclosure. 
         FIGS.  5 A and  5 B  are diagrams illustrating a cover applied to a mask according to an embodiment of the present disclosure. 
         FIG.  6    is a diagram illustrating a cover according to another embodiment of the present disclosure. 
         FIG.  7    is a diagram illustrating an example of forming an air pocket according to an embodiment of the present disclosure. 
         FIGS.  8 A to  8 D  are diagrams illustrating a flow of air during breathing according to an embodiment of the present disclosure. 
         FIG.  9    is a diagram illustrating a noise reduction effect according to an embodiment of the present disclosure. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Advantages and features of the present disclosure and methods for accomplishing the same will be more clearly understood from exemplary embodiments described below with reference to the accompanying drawings. However, the present disclosure is not limited to the following embodiments but may be implemented in various different forms. The embodiments are provided only to complete disclosure of the present disclosure and to fully provide a person having ordinary skill in the art to which the present disclosure pertains with the category of the present disclosure, and the present disclosure will be defined by the scope of the appended claims. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     Spatially-relative terms such as “below”, “beneath”, “lower”, “above”, or “upper” may be used herein to describe one element&#39;s relationship to another element as illustrated in the Figures. It will be understood that spatially-relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below. Since the device may be oriented in another direction, the spatially-relative terms may be interpreted in accordance with the orientation of the device. 
     The terminology used in the present disclosure is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. As used in the disclosure and the appended claims, the singular forms are intended to include the plural forms as well, unless context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated components, steps, and/or operations, but do not preclude the presence or addition of one or more other components, steps, and/or operations thereof. 
     It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. 
     It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     In the drawings, the thickness or size of each constituent element is exaggerated, omitted, or schematically illustrated for convenience of description and clarity. Also, the size or area of each constituent element does not entirely reflect the actual size thereof. 
     In general, a suffix such as “module” and “unit” used to refer to elements or components in the following description is merely intended to facilitate description of the specification, and the suffix itself is not intended to give any special meaning or function. 
     Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. 
       FIGS.  1 A and  1 B  are diagrams illustrating a general mask. 
     As described above, the guide vane  11  of  FIG.  1 A  or the porous passage  12  of  FIG.  1 B  are applied to the general mask in an attempt to optimize a flow passage, but the general mask still has a problem in that turbulence noise is generated due to a non-uniform suction flow. 
     Accordingly, a mask  10  according to an embodiment of the present disclosure may include an air purifying module  100  allowing for a uniform suction flow, without applying the guide vane  11  or the porous passage  12 . 
       FIG.  2    is a diagram illustrating a mask according to an embodiment of the present disclosure. 
     Referring to  FIG.  2   , the mask  10  may include a mask main body  20  pressed against a user&#39;s face, and the air purifying module  100  mounted in the mask main body  20 . 
     The mask main body  20  may be pressed against a user&#39;s face to form an internal space for receiving air in front of the user&#39;s nose and mouth. The mask main body  20  may have an inlet  22  providing a passage through which outside air may flow into the internal space. Further, the mask main body  20  may have a mounting part  21  on which the air purifying module  100  is mounted. The mask main body  20  may have a discharge part  25  providing a passage through which internal air may be discharged to the outside. 
     The inlet  22  may have one or more holes  23 . Air having passed through the air purifying module  100  may flow into the internal space through the one or more holes  23 . The discharge part  25  may be disposed below the inlet  22 . The discharge part  25  may discharge the internal air to the outside by allowing the air to flow in one direction. 
     There may be one or more discharge parts  25 . The discharge part  25  may allow air to flow in one direction. That is, the discharge part  25  may discharge the air inside the mask main body  20  to an external space. However, the outside air may not flow into the internal space of the mask main body  20  through the discharge part  25 . For example, a check valve may be provided for the discharge part  25 . 
     The air purifying module  100  may force the outside air to flow into the user&#39;s nose sand mouth. In this case, the air purifying module  100  may force the outside air to flow in a direction perpendicular to a side surface of the air purifying module  100 . The air purifying module  100  may have a first passage for the flow of air. 
     There may be one or more air purifying modules  100 . 
     In the case where there is one air purifying module  100 , the air purifying module  100  may be mounted on one side of the mask main body  20 , and the one side of the mask main body  20  may be the left side or the right side of a user&#39;s face when the user wears the mask  10 . 
     In the case where there are two air purifying modules  100 , the air purifying modules  100  may include a first air purifying module  101  mounted on one side of the mask main body  20 , and a second air purifying module  102  mounted on the other side of the mask main body  20 . In this case, the one side of the mask main body  20  may be the left side or the right side of the user&#39;s face when the user wears the mask  10 . The other side of the mask main body  20  may be the right side or the left side of the user&#39;s face when the user wears the mask  10 . 
     In the case where there are two air purifying modules  100 , the mask main body  20  may include a first inlet and a second inlet providing passages for the outside air to flow into the internal space. Air filtered by the first air purifying module  101  may flow into the internal space through the first inlet. Air filtered by the second air purifying module  102  may flow into the internal space through the second inlet. 
     The mask main body  20  may have a first discharge part disposed below the first inlet. The mask main body  20  may have a second discharge part disposed below the second inlet. The first discharge part and the second discharge part may discharge the internal air to the external space by allowing the air to flow in one direction. That is, when the user exhales, the internal air may be discharged to the outside through at least either the first discharge part or the second discharge part. 
     The first air purifying module  101  may have a la passage for allowing air to flow in a direction perpendicular to the side surface while forcing the outside air to flow into the user&#39;s nose and mouth. 
     The following description of the air purifying module  100  may be applied to the first air purifying module  101 . That is, each component including a cover  110 , a filter  120 , a fan  130 , and a case  140 , which will be described later, and sub-components thereof may be understood as a first cover, a first filter, a first fan, a first case, and sub-components thereof. 
     The second air purifying module  102  may have a  1   b  passage for allowing air to flow in a direction perpendicular to the side surface while forcing the outside air to flow into the user&#39;s nose and mouth. 
     The second air purifying module  102  may include a second cover, a second filter, a second fan, a second case, and sub-components thereof, which correspond to the first cover, the first filter, the first fan, the first case, and the sub-components thereof. 
     The second air purifying module  102  may be bilaterally symmetrical to the first air purifying module  101  with respect to a central line  30  of the mask main body  20 . That is, the second cover, the second filter, the second fan, the second case, and the sub-components thereof may be bilaterally symmetrical to the first cover, the first filter, the first fan, the first case, and the sub-components thereof with respect to the center line  30 . 
     Hereinafter, a description of the second cover, the second filter, the second fan, the second case, and the sub-components thereof will be omitted, but may be easily understood by those skilled in the art, since the role and function thereof are the same as the cover  110 , the filter  120 , the fan  130 , the case  140 , and the sub-components thereof which will be described later. 
       FIG.  3    is a diagram illustrating a mask main body according to an embodiment of the present disclosure. 
     Referring to  FIG.  3   , the mask main body  20  may include a mounting part  21 , an inlet  22 , and a discharge part  25 . 
     The mask main body  20  may be coupled to the air purifying module  100  via the mounting part  21 . The air purifying module  100  may be mounted in the mounting part  21 . Specifically, the air purifying module  100  may include the case  140 , and a lower end of the case  140  may be mounted in the mounting part  21 . 
     The inlet  22  may be provided on a side surface toward the center line  30  of the mounting part  21 . That is, when the mounting part  21  is located on a right side surface of the mask main body  20 , the inlet  22  may be formed on a left side surface of the mounting part  21 . Further, when the mounting part  21  is located on a left side surface of the mask main body  20 , the inlet  22  may be formed on a right side surface of the mounting part  21 . 
     The mask main body  20  may be coupled to the air purifying module  100  via the inlet  22 . A portion of the air purifying module  100  may be mounted in the inlet  22 . Specifically, the air purifying module  100  has a connection part  145 , and one surface of the connection part  145  may be mounted in the inlet  22 . 
     In addition, the other surface of the connection part  145  may come into contact with the case  140 , such that the connection part  145  may connect the case  140  and the inlet  22 . 
     The inlet  22  may have one or more holes  22 . Referring to  FIG.  3   , it is illustrated that there is one hole  23 , but the hole  23  is not limited thereto, and the inlet  22  may have a plurality of holes. 
     The hole  23  may form a second passage through which the filtered air may flow into the internal space of the mask main body  20 . The second passage may refer to a passage through which air, having passed through the fan  130 , passes through the case  140  and the internal space of the connection part  140  to reach the hole  23 . In this case, the size of the hole  23  may be smaller than the size of the inlet  22 . 
     The discharge part  25  may be disposed below the inlet  22 . The position of the discharge part  25  may correspond to the user&#39;s nose or mouth. That is, the discharge part  25 , which is disposed below the inlet  22 , may effectively discharge air, exhaled by the user, to the external space. 
     The discharge part  25  may discharge the internal air to the external space by allowing the air to flow in one direction. To this end, a check valve may be provided for the discharge part  25 . The check valve opens when the internal air is discharged to the external space, and shuts when the outside air flows into the internal space. 
     In other words, when the user inhales, the check value shuts such that the outside air is introduced through the air purifying module  100 ; and when the user exhales, the check value opens such that the internal air may be discharged to the external space through the discharge part  25 . 
     The mask main body  20  may further include ear loops  24 . The mask main body  20  may include the ear loops  24  formed on both sides of the mask main body  20  to be hung on the user&#39;s ears. The ear loops  24  may fix the mask main body  20  by allowing the mask main body  20  to be pressed against the user&#39;s face. 
       FIG.  4    is a cross-sectional view of an air purifying module according to an embodiment of the present disclosure. 
     Referring to  FIG.  4   , the air purifying module  100  may include the case  140  forming the exterior of the air purifying module  100 , the cover  110  covering a portion of the case  140 , the filter  120  filtering air introduced from the outside, and the fan  130  disposed in the case  140  and formed on the inside of the filter  120 . 
     In the following description, the inside indicates a direction of a user&#39;s face or a direction of the internal space formed by a mask when the user wears the mask, and the outside indicates a direction a direction opposite to the user&#39;s face or a direction of the external space. 
     The case  140  may form the exterior of the air purifying module  100 , and may have one open surface. The fan  130  and the filter  120  may be stacked through the open surface of the case  140 . 
     The cover  110  may cover a portion of the case  140 . Specifically, the cover  110  may be disposed to cover the open surface of the case  140 . The cover  110  may have a curved surface portion  111  having a convex curvature outwardly of the cover  110 , and a flat surface portion  112  extending in a direction parallel to the filter  120  from an edge of the curved surface portion  111 . 
     A detailed description of the cover  110  will be given later with reference to  FIGS.  5 A and  5 B . 
     The filter  120  may be disposed inside the case  140  to be fixed to the case  140 . The filter  120  may filter out foreign matter from air flowing through the first passage. The filter  120  may have a filter member for filtering out foreign matter. For example, the filter member may include a mesh filter in the form of a mesh, an electrostatic filter filtering out foreign matter using static electricity, and the like. 
     The filter  120  may be detachably mounted in the case  140 . Accordingly, when the filter  120  is contaminated, a user may replace the contaminated filter  120 . 
     The fan  130  may be disposed on the inside the filter  120 . 
     The fan  130 , disposed inside the case  140 , may draw in air having passed through the filter  120 . Although not illustrated herein, the fan  130  may include a fan motor. The fan motor may be a motor for driving rotation of the fan  130 . That is, when the fan  130  is rotated by the operation of the fan motor, outside air may be introduced by the fan  130 . Further, depending on embodiments, the fan motor may drive the fan  130  to rotate to discharge exhaled air. 
     A thickness of the fan  130  may be less than a reference thickness. In addition, a speed of rotation of the fan  130  may be faster than a reference speed of rotation so as to overcome a flow resistance of the filter  120 . For example, the reference speed of rotation may be 8,000 rpm. A distance between the fan  130  and the filter  120  may be smaller than a reference distance. 
     If the speed of rotation of the fan  130  is fast but the distance between the fan  130  and the filter  120  is small, a flow velocity of air drawn in through the fan  130  may be concentrated at a specific portion. That is, the entire area of the filter  120  may not be used effectively. However, the problem may be overcome by providing an air pocket according to an embodiment of the present disclosure between the filter  120  and the cover  110 . 
     The fan  130  may be a centrifugal type fan. That is, the fan  130  may draw in air, filtered by the filter  120 , in a direction perpendicular to the fan  130 , and may discharge the air in a radial direction of the fan  130 . The connection part  145  is disposed radially of the fan  130 , and the air discharged from the fan  130  may flow into the internal space of the mask  10  through the connection part  145 . By using such centrifugal type fan, the thickness of the fan  130  may be reduced, thereby reducing the thickness of the case  140 , as well as the thickness and weight of the air purifying module  100 . 
     The case  140  may include a first case  141  having the filter  120 , a second case  142  having the fan  130 , and the connection part  145  connecting the second case  142  and the mask main body  20 . 
     The filter  120  may be disposed inside the first case  141 , and the first case  141  may fix the filter  120 . A recess  143  may be formed in the first case  141 , and the cover  110  may be fixed or supported in the recess  143 . 
     The fan  130  may be disposed inside the second case  142 , and the second case  142  may fix the fan  130 . A connection hole  144  is formed on one surface of the second case  142 , and the second case  142  may be connected to the connection part  145  through the connection hole  144 . 
     The following description will be given without distinguishing the first case  141  and the second case  142 , but the following description of the case  140  may be applied to both the first case  141  and the second case  142 . 
     The connection part  145  may be inclined downwardly toward the center line  30  of the mask main body  20  from one surface of the case  140 . Referring to  FIG.  4   , it is illustrated that the connection part  145  is a curved surface and is inclined downwardly, but is not limited thereto. That is, the connection part  145  may be a flat surface and may be inclined downwardly. 
     The connection part  145  may be connected to the inlet  22  of the mask main body  20 . 
     The connection hole  144  may be formed on one surface of the second case  142 . Air, having passed through the fan  140 , may flow into the connection part  145  through the connection hole  144 . The connection part  145  may have a second passage formed therein, through which outside air, having passed through the filter  120  and the fan  130 , flows into the mask main body  20 . 
     To sum up, the air having passed through the filter  120  is introduced into the fan  130  in a direction perpendicular to the fan  130  and is discharged in the radial direction of the fan  130 , to flow into the internal space of the mask main body  20  through the second passage connecting the connection hole  144 , the internal space of the connection part  145 , and the hole  23  of the inlet  22 . 
     In the mask  10  according to an embodiment of the present disclosure, the connection part  145  is formed toward the center line  30 , such that the air filtered by the filter  120  may be concentrated on a user&#39;s mouth and nose. That is, the second passage may guide a flow of the filtered air to be concentrated on the user, thereby improving user-friendliness. 
       FIGS.  5 A and  5 B  are diagrams illustrating a cover applied to a mask according to an embodiment of the present disclosure. 
       FIG.  5 A  is a perspective view of the cover  110 , and  FIG.  5 B  is a top view of the cover  110 . 
     Referring to  FIGS.  5 A and  5 B , the cover  110  may have a curved surface portion  111  having a convex curvature outwardly of the cover  110 , and a flat surface portion  112  extending in a direction parallel to the filter  120  from an edge of the curved surface portion  111 . In addition, the cover  110  may further include a protrusion  113  which protrudes inwardly of the cover  110  from the flat surface portion  112 , to be coupled to the case  140  to fix the cover  110 . 
     The cover  110  may be disposed to cover the open surface of the case  140 , and may be spaced apart from the case  140  by a predetermined distance. The fan  130  and the filter  120  are sequentially stacked inside the case  140 , and thus the cover  110  may be spaced apart from the filter  120 . As the cover  110  and the filter  120  are spaced apart from each other, an air pocket may be formed as a space between the cover  110  and the filter  120 . 
     The curved surface portion  111 , formed as a portion of the cover  110 , may have a curvature outwardly of the cover  110 . A distance between the cover  110  and the filter  120  may increase with the curved surface portion  111 . That is, the air pocket, which is a space between the cover  110  and the filter  120 , may be formed wide by the curved surface portion  111 . Further, the filter  120  may uniformly draw in air through the air pocket. 
     The flat surface portion  112  may be a portion of the cover  110  except the curved surface portion  111 . The flat surface portion  112  may have the protrusion  113 . The protrusion  113 , which is coupled to the case  140  to fix the cover  110 , is formed on the flat surface portion  112  rather than on the curved surface portion  111 , thereby stably fixing the cover  110 . 
     The cover  110  may be detachably coupled to the case  140  by the protrusion  113 . A user may detach the cover  110  to replace the filter  120 , and when the cover  110  is attached, the cover  110  may be fixed to the case  140 . In addition, the protrusion  113  may support the cover  110 . 
     Referring to  FIG.  5 A , the cover  110  may be spaced apart from the case  140  by the protrusion  113 , and the outside air may flow into the case  140  through the separated space. As illustrated herein, when the cover  110  has a rectangular shape, the outside air may be introduced from all four sides, i.e., top, bottom, left, and right sides, of the cover  110 . 
     The four sides of the cover  110  may refer to lateral surfaces of the air purifying module  100 . That is, the outside air may flow into the air purifying module  100  through the lateral surfaces. In this case, the outside air may flow into the air purifying module  100  through the first passage. The first passage may refer to a path through which the outside air may flow into the air purifying module  100 . 
     Specifically, the outside air may be introduced in a direction perpendicular to the lateral surface of the case  140  forming the exterior of the air purifying module  100 . The lateral surface of the case  140  may be the same as the lateral surface of the air purifying module  100 . Accordingly, as the case  140  and the cover  110  are spaced apart from each other, the first passage may be formed for the flow of air in a direction perpendicular to the lateral surface of the air purifying module  100 . 
     As the air flows through the first passage, the first passage may reduce noise caused by the air flow. Further, the first passage provides a wider suction area than a porous passage, thereby reducing a flow rate loss and a pressure loss. 
     Referring to  FIG.  5 B , a first direction  500  may refer to a lengthwise direction (up-down direction of  FIG.  5 B ) of the cover  110 . A first direction length  510  of the protrusion  113  may be shorter than a first direction length  520  of the cover  110 . If the first direction length  510  of the protrusion  113  is equal to or longer than the first direction length  520  of the cover  110 , the flow of air in a left-right direction of the cover  110  may be blocked. 
     Accordingly, the first direction length  510  of the protrusion  113 , which is shorter than the first direction length  520  of the cover  110 , may allow the air purifying module  100  to generate a flow on four top, bottom, left, and right sides of the cover  110 , thereby enhancing air purification efficiency. 
       FIG.  6    is a diagram illustrating a cover according to another embodiment of the present disclosure. 
     Referring to  FIG.  6   , a cover  610  may have a circular shape. The circular cover  610  may have a curved surface portion  611  having a convex curvature outwardly of the cover  110 , and a flat surface portion  612  extending in a direction parallel to the filter  120  from an edge of the curved surface portion  111 . In addition, the cover  610  may further include a protrusion  613  which protrudes inwardly of the cover  610  from the flat surface portion  612 , to be coupled to the case  140  to fix the cover  610 . 
     The circular cover  610  of  FIG.  6   , which is different only in shape from the cover  110  of  FIG.  5 A , may perform the same function as the cover  110  of  FIG.  5 A . However, in the case of the circular cover  610 , the air purifying module  100  may draw in outside air in all directions along the edge of the cover  610 , thereby further improving air flow performance. 
     Accordingly, all of the descriptions of the cover  110  of  FIG.  5 A , except the description of the four top, bottom, left, and right sides of the cover  110 , may be applied to the circular cover  610  of  FIG.  6   . 
       FIG.  7    is a diagram illustrating an example of forming an air pocket according to an embodiment of the present disclosure. 
     Referring to  FIG.  7   , as the cover  110  and the filter  120  are spaced apart from each other, the air pocket  115  may be formed in a space between the cover  110  and the filter  120 . 
     The curved surface portion  111  may have a curvature outwardly of the cover  110 . Accordingly, a distance between the cover  110  and the filter  120  may increase compared to a case where the cover has only the flat surface portion  112 . 
     The distance between the cover  110  and the filter  120  may be largest at the center of the curved surface portion  111 . That is, the air pocket  115 , which is a space between the cover  110  and the filter  120 , may be formed wide by the curved surface portion  111 . The outside air is introduced into a narrow space between the flat surface portion  112  and the case  140 , to reach the wide air pocket  115 , such that pressure of the air may be reduced. 
     The outside air, introduced through the first passage, may flow along the curved surface portion  111  inside the air pocket  115  having a reduced pressure. While flowing along the curved surface portion  111 , the outside air may spread uniformly inside the air pocket  115 . The uniformly spread air may be introduced uniformly into the filter  120  by a suction force of the fan  130 . 
     That is, as the cover  110 , having the curved surface portion  111 , and the filter  120  are spaced apart from each other, the air pocket  115  is formed between the cover  110  and the filter  120 , and the outside air introduced into the air pocket  115  may spread uniformly inside the air pocket  115  along the curved surface portion  111 . Accordingly, the filter  120  may uniformly draw in the outside air, and the entire area of the filter  120  may be used efficiently, thereby improving performance and durability of the filter  120 . 
     In order to introduce large amounts of air into the air pocket  115 , the cover  110  may be spaced apart from the case  140 . The cover  110  has no porous passage, such that the air may flow through the first passage formed as a space between the cover  110  and the case  140 . The cover  110  has the protrusion  113  and is supported by the protrusion  113 , such that the cover  110  may be spaced apart from the case  140 . 
     The case  140  may have the recess  143  in which the protrusion  113  is received. Specifically, the recess  143  may be formed in the first case  141 . The protrusion  113  may be coupled to the recess  143 . By receiving the protrusion  113 , the recess  143  may fix the protrusion  113 , such that the first case  141  may fix the cover  110 . 
     Further, by receiving the protrusion  113 , the recess  143  may support the cover  110 . As the protrusion  113  is coupled to the recess  143 , the protrusion  113  may support the cover  110 . In this case, the cover  110  and the case  140  may be spaced apart from each other. 
     A second direction length  710  of the protrusion  113  may be longer than a depth  720  of the recess  143 . A second direction  700  may refer to an inward direction (downward direction in  FIG.  7   ). If the second direction length  710  of the protrusion  113  is equal to the depth of the recess  143 , the cover  110  and the case  140  come into contact with each other, such that the first passage may not be formed or may be narrowed, thereby reducing a suction flow rate. Accordingly, in order to allow the cover  110  and the case  140  to be spaced apart from each other, the second direction length  710  of the protrusion  113  is formed to be longer than the depth  720  of the recess  143  by a predetermined value or more, thereby securing a sufficient first passage. 
       FIGS.  8 A to  8 D  are diagrams illustrating a flow of air during breathing according to an embodiment of the present disclosure. 
       FIGS.  8 A to  8 D  are diagrams explaining a moving path of air when a user inhales. When the user exhales, the air may be discharged to the outside through the discharge part  25  of  FIGS.  2  and  3   , although not illustrated separately. 
     Referring to  FIGS.  8 A to  8 D , the following description will be given based on the flow of air during a user&#39;s inhalation. 
     Referring to  FIG.  8 A , the outside air may flow into the air purifying module  100  through the first passage formed between the cover  110  and the first case  141  (S 810 ). The first passage may be formed perpendicular to the lateral surface of the air purifying module  100 . A direction of the lateral surface of the air purifying module  100  may be equal to a direction of the lateral surface of the case  140  and a direction of the lateral surface of the cover  110 . 
     If the air purifying module  100  has a circular shape, the first passage may be formed in a radial direction of the air purifying module  100 . In this case, the outside air may be introduced in a forward direction, which is a direction perpendicular to the side of the air purifying module  100 . 
     If the air purifying module  100  has a rectangular shape, the first passage may be formed in a direction perpendicular to four sides of top, bottom, left, and right of the lateral surface of the air purifying module  100 . In this case, the outside air may be introduced in a direction perpendicular to the lateral surface of the air purifying module  100 . 
     Referring to  FIG.  8 B , the outside air introduced through the first passage may spread uniformly inside the air pocket  115  (S 820 ). The air pocket  115 , formed as a space between the cover  110  and the filter  120 , may be formed wide by the curved surface portion  111  of the cover  110 . The outside air may spread uniformly along the curved surface portion  111  inside the air pocket  115  having a reduced pressure. 
     As the distance between the filter  120  and the fan  130  decreases, the volume and weight of the air purifying module  100  may be reduced. Accordingly, the distance between the filter  120  and the fan  130  may be formed to be equal to or less than a predetermined distance. 
     However, while the distance between the filter  120  and the fan  130  is equal to or less than a predetermined distance, if the fan  130  rotates at a high rpm equal to or higher than 8,000 rpm, a non-uniform air flow may be generated. The air pocket  115  may prevent such non-uniform air flow. That is, by reducing pressure between the cover  110  and the filter  120 , the air pocket  115  may generate a uniform suction flow. 
     Referring to  FIG.  8 C , the outside air, spreading uniformly by the air pocket  115 , may be uniformly drawn into the filter  120  and the fan  130  by the torque of the fan  130  (S 830 ). Accordingly, the entire area of the filter  120  may be used uniformly, and performance and durability of the filter  120  may be improved. 
     The fan  130  may be a centrifugal type fan. The fan  130  may draw in air, having filtered by the filter  120 , in a direction perpendicular to the fan  130 , and may discharge the air in a radial direction of the fan  130 . Specifically, the fan  130  may discharge the air toward the connection hole  144 . By using the centrifugal type fan, a thickness of the fan  130  may be reduced, thereby reducing the thickness of the case  140 , as well as the volume and weight of the air purifying module  100 . 
     Referring to  FIG.  8 D , the air discharged in the radial direction of the fan  130  may flow into the internal space of the mask main body  20  through the second passage formed in the internal space of the connection part  145  (S 840 ). 
     The connection part  145  may be disposed radially of the fan  130 . Specifically, the connection part  145  may be inclined downwardly toward the center line  30  of the mask main body  20  from one surface of the case  140 , and may be connected to the inlet  22  of the mask main body  20 . The connection hole  144  may be formed on one surface of the case  140 . Air having passed through the fan  130  may flow into the connection part  145  through the connection hole  144 , and may flow into the internal space of the mask main body  20  through the hole  23  of the inlet  22 . 
       FIG.  9    is a diagram illustrating a noise reduction effect according to an embodiment of the present disclosure. 
     Referring to  FIG.  9   , the mask  10  according to an embodiment of the present disclosure has a noise reduction effect compared to a mask having a general fan. 
     By measuring noise (dB) with respect to air volume (LPM), it can be seen that a noise level of the mask  10  as shown in graph  920  is reduced, compared to the mask having the general fan as shown in graph  910 . In the general mask, a porous passage is mostly applied in order to optimize a passage. In this case, a loud noise is generated by a non-uniform suction flow. 
     In the mask  10  according to an embodiment of the present disclosure, noise may be reduced while increasing a suction area through the first passage, without using the porous passage. Further, by providing the curved surface portion  111  on the cover  110 , the air pocket  115  may be formed between the cover  110  and the filter  120 . 
     Particularly, a largest gap is formed between the center of the cover  110  and the filter  120 , and preferably a gap of 5 mm may be formed therebetween. By using the air pocket  115 , a space for the flow of air may be further provided compared to the cover having a flat surface shape. In addition, the air pocket  115  may overcome the nonuniformity of the suction flow, and may provide a noise reduction effect as well as an effect of reducing pressure between the filter  120  and the cover  110 . 
     While preferred embodiments of the present disclosure have been described and illustrated herein, the present disclosure is not limited to the specific embodiments described above. It should be understood that various modifications of the embodiments are possible by those skilled in the art without departing from the technical scope of the present disclosure defined by the appended claims, and the modifications should not be understood separately from the technical principles or prospects of the present disclosure.