Patent Publication Number: US-8540449-B2

Title: Fluid-material spread apparatus having double roller

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a container which is capable of applying liquid material. More particularly, the present invention relates to a container which uses a dual roller structure to enable liquid material to be evenly applied. 
     2. Description of the Related Art 
     Conventional liquid material is applied to a desired location using the hand or a brush, after being discharged from a container containing the liquid material. For example, as for a liquid cosmetic container, a user discharges liquid cosmetic material from the cosmetic container to the palm of one hand or the like, and then applies the liquid cosmetic material to the desired skin portion using the fingers of the other hand or a brush. 
     During the operation of applying the liquid material, the liquid material may adhere to undesired places, for example, the hands or the clothing. Hence, the liquid material may cause contamination or the liquid material may be wasted. 
     In order to solve the problem, there has been proposed a structure wherein one roller for applying liquid material is mounted to a liquid container. However, in the case of applying the liquid material using only one roller, an excessively large or small amount of liquid material may adhere to the roller, so that it is impossible to uniformly apply the contents to the roller. Further, when an excessively large amount of liquid material adheres to the roller, the roller swells up, so that the roller is not easy to rotate. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a liquid-material application apparatus with a dual roller structure, which is intended to prevent liquid material from adhering to an undesired portion, when the liquid material is applied to a desired location such as the user&#39;s skin. 
     Another object of the present invention is to provide a liquid-material application apparatus with a dual roller structure, which allows liquid material to be evenly applied to a roller. 
     A further object of the present invention is to provide a liquid-material application apparatus with a dual roller structure, which enables the discharge of liquid material to be easily controlled by rotating a container to the left or right. 
     In order to accomplish the above objects, the present invention provides a liquid-material application apparatus with a dual roller structure, including a body having a space for holding contents therein, with a first discharge port being formed on an upper portion of the body to discharge the contents. 
     The apparatus includes a roller support placed on an upper portion of the body and having on a lower surface thereof a second discharge port which communicates with the first discharge port. 
     The apparatus includes a first roller unit rotatably placed above the lower surface of the roller support and making contact with the contents which are discharged from the second discharge port, and a second roller unit placed on a side of the first roller unit in such a way as to be put in contact with the first roller unit and rotatably coupled to the roller support. 
     When the second roller unit rotates, the first roller unit rotates while being in contact with the second roller unit, thus transferring the contents from the second discharge port to the second roller unit. 
     A concave part may be formed above the lower surface of the roller support to receive the first roller unit therein. 
     The second discharge port may be formed on the concave part to communicate therewith. 
     A step may be provided on an edge of the concave part, so that the first roller unit is seated at opposite ends thereof on the step, thus spacing a bottom surface of the concave part and the first roller unit apart from each other. 
     A rotating shaft may be provided on each of opposite ends of the first roller unit, and a shaft insert groove may be provided on the edge of the concave part so that the rotating shaft is seated therein. 
     The shaft insert groove may be formed to space the bottom surface of the concave part and the first roller unit apart from each other when the rotating shaft of the first roller unit is seated in the shaft insert groove. 
     A depressed portion may be formed in the concave part to hold contents discharged from the second discharge port, and the second discharge port may be formed to communicate with the depressed portion. 
     A coupling projection may project upwards from the upper portion of the body, and the first discharge port may be formed an upper portion of the coupling projection. 
     An extension part may be coupled to the coupling projection, and may include a through hole communicating with the first discharge port. 
     A check valve may be provided in the through hole of the body. 
     The extension part may have a cylindrical shape, and the roller support may have on the lower surface thereof a coupling piece which is rotatably coupled to the extension part. 
     A projection for opening or closing the through hole may be provided on the lower surface of the roller support in such a way as to extend downwards, so that the projection opens or closes the through hole when the roller support moves up or down. 
     Thread grooves may be formed on an outer circumference of the extension part, and threads may be formed on the coupling piece to be inserted into the thread grooves, whereby, if the roller support moves up according to a direction in which the roller support having the coupling piece rotates, the projection moves up, thus opening the outlet, and if the roller support moves down, the projection moves down, thus closing the outlet. 
     A nozzle having an outlet may be provided in the through hole, and a projection for opening or closing the outlet may be provided on the lower surface of the roller support in such a way as to extend downwards, so that the projection opens or closes the outlet when the roller support moves up or down. 
     Thread grooves may be formed on an outer circumference of the nozzle, and threads may be formed on the coupling piece to be inserted into the thread grooves, whereby, if the roller support moves up according to a direction in which the roller support having the coupling piece rotates, the projection moves up, thus opening the outlet, and if the roller support moves down, the projection moves down, thus closing the outlet. 
     A guide piece may protrude from an upper portion of the extension part, and a contact piece may be provided on the lower surface of the roller support to make contact with the guide piece, whereby, when the roller support rotates, so that the guide piece comes into contact with the contact piece, the projection is positioned so as to open the through hole or outlet. 
     The extension part may include on a side surface thereof a protrusion having a seating groove, and the roller support may include on the lower surface thereof a protruding piece which is inserted into the seating groove when the roller support rotates, so that the protruding piece is seated into the seating groove when the through hole or outlet is opened or closed. 
     A plurality of grooves may be formed on an outer surface of the first roller unit. 
     The grooves may be continuously formed in a direction perpendicular to a direction of rotation of the first roller unit or in the same direction as the direction of rotation thereof. 
     The grooves may be discontinuously formed in a direction perpendicular to a direction of rotation of the first roller unit or in the same direction as the direction of rotation thereof. 
     The grooves may be continuously or discontinuously formed in a direction inclined relative to a direction of rotation of the first roller unit. 
     The grooves may cross each other. 
     A plurality of protrusions may be formed on the first roller unit. 
     The first roller unit may include a plurality of balls. 
     At least one of the first and second roller units may comprise a plurality of rollers. 
     When the first roller unit comprises one roller and the second roller unit comprises two rollers, the roller of the first roller unit may be placed between first and second rollers of the second roller unit in such a way as to be in contact therewith, and the first and second rollers of the second roller unit may be spaced apart from each other. 
     When the first roller unit comprises two rollers and the second roller unit comprises one roller, first and second rollers of the first roller unit may be in contact with the roller of the second roller unit, and the first and second rollers of the first roller unit may be spaced apart from each other. 
     When the first roller unit comprises two rollers and the second roller unit comprises two rollers, a first roller of the first roller unit may be in contact with a first roller of the second roller unit, and a second roller of the first roller unit may be in contact with a second roller of the second roller unit, the first and second rollers of the first roller unit being spaced apart from each other, and the first and second rollers of the second roller unit being spaced apart from each other. 
     When the first roller unit comprises three rollers and the second roller unit comprises one roller, a central roller of the first roller unit may have on opposite sides thereof two peripheral rollers which are spaced apart from the roller of the second roller unit and are in contact with the central roller. 
     When the first roller unit comprises three rollers and the second roller unit comprises one roller, a central roller of the first roller unit may have on opposite sides thereof two peripheral rollers which are in contact with the central roller, and the roller of the second roller unit may be in contact with the peripheral rollers of the first roller unit, and the central roller of the first roller unit and the roller of the second roller unit may be spaced apart from each other. 
     When the first roller unit comprises three rollers and the second roller unit comprises two rollers, a central roller of the first roller unit may have on opposite sides thereof peripheral rollers which are spaced apart from each other, and first and second rollers of the second roller unit may be placed, respectively, between the central and peripheral rollers of the first roller unit, and the first and second rollers of the second roller unit may be spaced apart from each other and rotate the first roller unit when the second roller unit rotates. 
     Further, in order to accomplish the above objects, the present invention provides a liquid-material application apparatus with a dual roller structure, including a body having a space for holding contents therein, with a first discharge port being formed on an upper portion of the body to discharge the contents; a first roller support placed on an upper portion of the body, and having on a lower surface thereof a second discharge port which communicates with the first discharge port; a first roller unit rotatably placed on an upper portion of the first roller support, and making contact with the contents which are discharged from the second discharge port; a second roller support placed on the first roller support, and having a slit to permit a surface of the first roller unit to protrude therethrough; and a second roller unit rotatably coupled to the second roller support in such a way as to be in contact with the first roller unit which protrude through the slit, wherein, when the second roller unit rotates, the first roller unit rotates while being in contact with the second roller unit, thus transferring the contents from the second discharge port to the second roller unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view showing a liquid-material application apparatus with a dual roller structure according to the present invention; 
         FIG. 2  is an exploded perspective view showing a liquid-material application apparatus with a dual roller structure according to an embodiment of the present invention; 
         FIG. 3  is an exploded perspective view showing the liquid-material application apparatus with the dual roller structure, when viewed from an angle different from that shown in  FIG. 2 ; 
         FIG. 4  is an exploded perspective view showing a liquid-material application apparatus with a dual roller structure according to another embodiment of the present invention; 
         FIG. 5  is an exploded perspective view showing the liquid-material application apparatus with the dual roller structure, when viewed from an angle different from that shown in  FIG. 4 ; 
         FIG. 6  is a sectional view showing the liquid-material application apparatus with the dual roller structure of  FIG. 4 ; 
         FIGS. 7 to 9  are operational views of the liquid-material application apparatus with the dual roller structure according to the present invention; 
         FIG. 10  is a partial sectional view showing a liquid-material application apparatus with a dual roller structure according to another embodiment of the present invention; 
         FIG. 11  is a partial sectional view showing a liquid-material application apparatus with a dual roller structure according to a further embodiment of the present invention; 
         FIG. 12  is a partial sectional view showing a liquid-material application apparatus with a dual roller structure according to a further embodiment of the present invention; 
         FIGS. 13A to 13E  are perspective views showing various embodiments of a first roller unit included in the liquid-material application apparatus with the dual roller structure according to the present invention; 
         FIGS. 14A to 14G  are views showing various arrangements of first and second roller units included in the liquid-material application apparatus with the dual roller structure according to the present invention; and 
         FIG. 15  is an exploded perspective view showing a liquid-material application apparatus with a dual roller structure according to another embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention may be generally used as an application apparatus for a liquid cosmetic container. However, the present invention may be applied to various types of application apparatuses for discharging and applying liquid contents, without being limited to the application apparatus for the liquid cosmetic container. For example, the present invention may also be applied to an application apparatus for liquid medicines or liquid paint. 
     A ‘dual roller structure’ used herein is not limited to two rollers, but means that it has two roller units. If a first roller unit has one roller and a second roller unit has one roller, the total number of rollers is two. However, if the first roller unit has two rollers and the second roller unit has one roller, the total number of rollers is three. 
     Hereinafter, a liquid-material application apparatus with a dual roller structure according to the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a perspective view showing a liquid-material application apparatus with a dual roller structure according to the present invention.  FIG. 2  is an exploded perspective view showing a liquid-material application apparatus with a dual roller structure according to an embodiment of the present invention.  FIG. 3  is an exploded perspective view showing the liquid-material application apparatus with the dual roller structure, when viewed from an angle different from that shown in  FIG. 2 . 
     Further,  FIG. 4  is an exploded perspective view showing a liquid-material application apparatus with a dual roller structure according to another embodiment of the present invention.  FIG. 5  is an exploded perspective view showing the liquid-material application apparatus with the dual roller structure, when viewed from an angle different from that shown in  FIG. 4 .  FIG. 6  is a sectional view showing the liquid-material application apparatus with the dual roller structure of  FIG. 4 . 
     As shown in  FIG. 1 , the liquid-material application apparatus according to the present invention includes a body  100 , a roller support  200 , a first roller unit  300 , and a second roller unit  400 . The second roller unit  400  rotates while being in contact with a place on which application is to be performed, such as the skin. If the second roller unit  400  rotates, the first roller unit  300  making contact with the second roller unit  400  also rotates. 
     According to the present invention, the body  100  has a space  110  to hold contents therein. A first discharge port  120  is formed in an upper portion of the body  100  to discharge contents held in the space  110  (see  FIGS. 2 to 6 ). 
     The space  110  in the body  100  holds liquid material, such as liquid cosmetic material or medical ointment. When a user pressurizes the body  100  by pumping it with his or her hand, the liquid material held in the space  110  of the body  100  is discharged through the first discharge port  120 . 
     The roller support  200  is placed on the upper portion of the body  100 , as shown in  FIGS. 1 to 6 . 
     The roller support  200  receives the first and second roller units  300  and  400 . As shown in  FIGS. 2 and 4 , a second discharge port  210  is formed on a lower surface of the roller support  200  and communicates with the first discharge port  120 . 
     The first roller unit  300  received in the roller support  200  is disposed above the lower surface of the roller support  200 , and is in contact with contents which are discharged from the second discharge port  210 . The second roller unit  400  is disposed on a side of the first roller unit  300  in such a way as to be in contact with the first roller unit  300 . 
     When the second roller unit  400  rotates while being in contact with the surface on which application is to be performed, the first roller unit  300  is in contact with the second roller unit  400  and so rotates in conjunction with the second roller unit  400 . 
     When the first and second roller units  300  and  400  rotate, contents discharged from the second discharge port  210  are transferred through the first roller unit  300  to the second roller unit  400 . 
     The first and second roller units  300  and  400  according to the present invention may be made of soft material, such as a puff or a sponge, or may be made of hard material, according to the characteristics of the operation of application or the place on which application is to be made. 
     As shown in  FIGS. 2 and 4 , a concave part  220  is formed above the lower surface of the roller support  200  according to the present invention to receive the first roller unit  300  therein. 
     The concave part  220  is formed by depressing the lower surface of the roller support  200  down in a concave manner. The concave part  220  is formed in a shape corresponding to that of the first roller unit  300 , so that the first roller unit  300  may be received in the concave part  220 . 
     As shown in  FIGS. 2 and 4 , the second discharge port  210  is formed on the concave part  220  of the present invention to communicate therewith. Preferably, a depressed portion (see  FIG. 10 ) is formed in the surface of the concave part  220  on which the second discharge port  210  is formed, so that contents discharged from the second discharge port  210  are temporarily held in the depressed portion before the contents make contact with the first roller unit  300 . 
     As shown in  FIGS. 2 to 5 , a coupling projection  130  is provided on an upper portion of the body  100  according to the present invention in such a way as to project upwards, with the first discharge port  120  being formed on an upper portion of the coupling projection  130 . 
     The coupling projection  130  is coupled with an extension part  500  that will be described below, and extends upwards from the upper portion of the body  100 . 
     The coupling projection  130  may be formed in various shapes. According to this embodiment, as shown in  FIGS. 2 to 5 , the coupling projection  130  has the shape of a pipe which has at a central portion thereof the first discharge port  120 . 
     The extension part  500  is coupled to the coupling projection  130 . As shown in  FIGS. 2 to 5 , a through hole  510  is formed in a central portion of the extension part  200  to communicate with the first discharge port  120 . 
     Thus, liquid contents discharged through the first discharge port  120  move through the through hole  510 . A check valve  520  which is wide at upper and lower ends thereof may be provided in the through hole  510 . 
     As shown in  FIGS. 2 to 5 , if the check valve  520  is disposed in the through hole  510 , the check valve  520  moves up and down in the through hole  510  because of the difference between the pressure of the space  110  and the external pressure, thus opening or closing the through hole  510 . 
     If the pressure of the space  110  is higher than the external pressure, the check valve  520  moves up in the through hole  510  until the lower end of the check valve  520  closes the through hole  510 . During the movement of the check valve  520 , the through hole  510  is temporarily opened, so that liquid contents held in the space  110  are discharged to the outside of the body  100 . 
     In contrast, if the external pressure is higher than the pressure of the space  110 , the check valve  520  moves down in the through hole  510  until the upper end of the check valve  520  closes the through hole  510 . In this case, since the external pressure is higher than the pressure of the space  110 , the contents are not discharged from the space  110 . Such a state may occur when the body  100  pressurized by a user returns to its original state. 
     Meanwhile, if the pressure of the space  110  is equal to the external pressure, the check valve  520  may move in the direction of gravity. In the present invention, the principle whereby the body  100  is pressurized by a user and the pressurized body  100  returns to its original state is important. 
     The extension part  500  according to the present invention may have a cylindrical shape, as shown in  FIGS. 2 and 3 . Preferably, as shown in  FIG. 3 , a coupling piece  230  which is rotatably coupled with the extension part  500  is provided on the lower surface of the roller support  200 . 
     As shown in  FIGS. 2 and 3 , the coupling piece  230  may be directly coupled to the extension part  500 . Further, as shown in  FIGS. 4 and 5 , the coupling piece  230  may be coupled to the extension part  500  via a nozzle  600  which is mounted to the extension part  500 . 
     In the nozzle  600  shown in  FIGS. 4 and 5 , an outlet  610  is formed in the upper end of the nozzle  600  in such a way as to communicate with the through hole  510  of the extension part  500 . 
     As shown in  FIGS. 4 and 5 , the nozzle  600  may be assembled with the extension part  500 . Alternatively, the nozzle  600  may be integrated with the extension part  500 . 
     In the liquid-material application apparatus according to the present invention, as shown in  FIGS. 2 and 3 , a projection  250  (see  FIG. 6 ) may be provided on the lower surface of the roller support  200  in such a way as to extend downwards, thus opening or closing the through hole  510 . 
     When the roller support  200  moves up and down, the projection  250  opens or closes the through hole  510 . 
     Preferably, as shown in  FIGS. 2 and 3 , thread grooves  550  are formed on the outer circumference of the extension part  500  according to the present invention. Further, as shown in  FIG. 3 , threads  231  are formed on the coupling piece  230  to be inserted into the thread grooves  550 . 
     Thus, the roller support  200  may move up along the thread grooves  550  of the extension part  500  according to the direction in which the roller support  200  having the coupling piece  230  rotates. At this time, the projection  250  moves up, thus opening the outlet. 
     In contrast, if the roller support  200  rotates to move down, the projection  250  moves down, thus closing the outlet. 
     As shown in  FIGS. 4 and 6 , when the nozzle  600  is provided on the upper portion of the extension part  500 , the projection  250 , which is provided on the lower surface of the roller support  200  in such a way as to extend downwards, may open or close the outlet  610 . 
     Thus, when the roller support  200  moves up or down, the projection  250  opens or closes the outlet  610 . 
     As shown in  FIGS. 4 to 6 , thread grooves  620  may be formed on the outer circumference of the nozzle  600 , and threads  231  may be formed on the coupling piece  230  to be inserted into the thread grooves  620 . 
     Thus, if the roller support  200  moves up according to the direction in which the roller support  200  having the coupling piece  230  rotates, the projection  250  also moves up, thus opening the outlet  610 . In contrast, if the roller support  200  moves down, the projection  250  also moves down, thus closing the outlet  610 . 
     As shown in  FIGS. 4 to 6 , a guide piece  530  protrudes from the upper portion of the extension part  500  of the liquid-material application apparatus according to the present invention, and a contact piece  240  is provided on the lower surface of the roller support  200  to be in contact with the guide piece  530 , as shown in  FIG. 6 . When the roller support  200  rotates so that the guide piece  530  comes into contact with the contact piece  240 , the projection  250  is in a position that opens the through hole  510  or the outlet  610 . 
       FIGS. 7 to 9  are operational views of the liquid-material application apparatus with the dual roller structure according to the present invention. The process of closing the outlet  610  of the nozzle  600  by the projection  250  will be described with reference to  FIGS. 7 to 9 . 
       FIG. 7  shows a case wherein the guide piece  530  and the contact piece  240  are on opposite sides of the through hole  510  of the extension part  500 . 
     If the coupling projection  130  of the roller support  200  is at the lowermost position along the thread grooves  620  of the nozzle  600 , the projection  250  of the roller support  200  moves down and closes the outlet  610  of the nozzle  600 . 
     In this state, the projection  250  comes into contact with the outlet  610  of the nozzle  600  as shown in  FIG. 7 , so that the roller support  200  may not rotate any further down along the thread grooves  620  of the nozzle  600 . 
     If the roller support  200  rotates in the state of  FIG. 7 , so that the coupling projection  230  of the roller support  200  moves along the thread grooves  620  of the nozzle  600  as shown in  FIG. 8 , the roller support  200  moves up. 
     At this time, the projection  250  provided on the lower portion of the roller support  200  also moves up. Thus, the projection  250  is spaced apart from the outlet  610  of the nozzle  600 , so that the outlet  610  of the nozzle  600  is in the open position. 
     When the roller support  200  is further rotated from the position of  FIG. 8  to a position of  FIG. 9 , the contact piece  240  provided on the roller support  200  comes into contact with the guide piece  530  provided on the extension part  500 , and stops any further rotation of the roller support  200 . 
     At this time, since the roller support  200  has moved to an upper position than the position of  FIG. 8 , the outlet  610  of the nozzle  600  is more widely open. 
     If the contact piece  240  and the guide piece  530  rotate at 180 degrees as shown in  FIGS. 7 to 9 , the contact piece  240  and the guide piece  530  may be on opposite sides of the through hole  510  so that the contact piece  240  comes into contact with the guide piece  530 . However, it is obvious to those skilled in the art that the positions of the contact piece  240  and the guide piece  530  may change depending on the amount of liquid material discharged from the container  100 . 
     When the coupling piece  230  is directly coupled to the extension part  500  having the thread grooves  550  as shown in  FIGS. 2 and 3 , the guide piece  530  may be formed on the upper portion of the extension part  500 , as shown in  FIGS. 2 and 3 . 
     Here, the contact piece  240 , which is in contact with the guide piece  530 , is preferably formed on the inner surface of the coupling piece  230 . 
     Preferably, a protrusion  540  having a seating groove  541  is provided on a side surface of the extension part  500  according to the present invention as shown in  FIGS. 2 to 5 , and a protruding piece  260  which makes contact with the protrusion  540  is formed on the lower surface of the roller support  200 , as shown in  FIGS. 3 and 5 . 
     The protrusion  540  and the protruding piece  260  may perform the function of informing a user of the position to which the roller support  200  has rotated, and the function of controlling the rotation. When the roller support  200  rotates, the protruding piece  260  is inserted into the seating groove of the protrusion  540  to hinder the smooth rotation of the roller support  200 , thus informing a user of the position to which the roller support  200  has rotated. 
     The protrusion  540  and the protruding piece  260  may be formed at various positions. When the through hole  510  or the outlet  610  is opened or closed, it is preferable that the protruding piece  260  be seated in the seating groove  541 . 
       FIGS. 10 to 12  are partial sectional views showing liquid-material application apparatuses with dual roller structures according to other embodiments of the present invention. Referring to the drawings, the concave part  220  and the first roller unit  300  may be formed as follows. 
     A step  221  may be formed on an edge of the concave part  220  so that both ends of the first roller unit  300  are seated thereon, thus allowing a bottom surface of the concave part  220  and the first roller unit  300  to be spaced apart from each other (see  FIG. 10 ). 
     In this case, liquid contents discharged from the second discharge port  210  may be evenly distributed between a space between the first roller unit  300  and the concave part  200 . Thus, the liquid contents may be more uniformly applied to the first roller unit  300 . 
     Further, in order to more smoothly rotate the first roller unit  300 , a rotating shaft  330  may be provided on each of opposite ends of the first roller unit  300  (see  FIG. 11 ). Further, a shaft insert groove  222  may be formed in an edge of the concave part  220  so that the rotating shaft  330  is seated therein. 
     Here, a height of the shaft insert groove  222  from the lower surface of the concave part  200  corresponds to a distance from the outer circumference of the first roller unit  300  to the rotating shaft  330 . Thereby, when the first roller unit  300  having the rotating shaft  330  is seated in the concave part  220 , the first roller unit  300  may be in close contact with the bottom surface of the concave part  220 . 
     Further, a height of the shaft insert groove  222  from the lower surface of the concave part  200  may be larger than a distance from the outer circumference of the first roller unit  300  to the rotating shaft  330 , thus allowing the bottom surface of the concave part  220  to be spaced apart from the first roller unit  300  (see  FIG. 12 ). 
       FIGS. 13A to 13E  are perspective views showing various embodiments of the first roller unit  300  of the liquid-material application apparatus according to the present invention. The various embodiments of the first roller unit  300  will be described in detail with reference to  FIGS. 13A to 13E . 
     According to the present invention, the first roller unit  300  may have a cylindrical shape. Such a first roller unit  300  may have on an outer surface thereof a plurality of grooves  310 . The grooves  310  formed in the first roller unit  300  may be oriented in a direction perpendicular to the direction of rotation of the first roller unit  300  as shown in  FIG. 13A , or may be oriented in the same direction as the direction of rotation as shown in  FIG. 13D . The grooves  310  may be continuously or discontinuously formed. 
     Further, the grooves  310  of the first roller unit  300  according to the present invention may be continuously formed in a direction which is inclined relative to the rotating direction of the first roller unit  310 , as shown in  FIG. 13B , or may be discontinuously formed according to an embodiment. Further, the grooves  310  may cross each other as shown in  FIG. 13C . 
     A plurality of protrusions  320  may be formed on the outer surface of the first roller unit  300  according to the present invention, as shown in  FIG. 13E . Further, a plurality of depressions (not shown) may be formed concavely in the first roller unit  300 . 
     The grooves  310  formed on the outer surface of the first roller unit  300  may be formed at various depths and intervals according to embodiments. The protrusions  220  of  FIG. 13E  may also be formed in various shapes. 
       FIGS. 14A to 14G  are views showing various embodiments of the first and second roller units  300  and  400  according to the present invention. The first and second roller units  300  and  400  will be described in detail with reference to  FIGS. 14A  to  14 G. 
     As shown in  FIGS. 14B to 14G , it is preferable that at least one of the first and second roller units  300  and  400  include a plurality of rollers. 
     As shown in  FIG. 14B , the first roller unit  300  may include one roller, and the second roller unit  400  may include two rollers. In this case, it is preferable that the roller of the first roller unit  300  be arranged between the rollers of the second roller unit  400  in such a way as to be put in contact with the rollers of the second roller unit  400 . It is preferable that the rollers of the second roller unit  400  be spaced apart from each other. 
     When the first and second roller units  300  and  400  are arranged as shown in  FIG. 14B , the two rollers of the second roller unit  400  rotate in the same direction. At this time, the roller of the first roller unit  300  rotates in a direction opposite to the rollers of the second roller unit  400 , thus transmitting contents from the second discharge port  210  to the rollers of the second roller unit  400 . 
     Thus, the contents transmitted to the second roller unit  400  may be evenly applied over a larger area. 
     Further, as shown in  FIG. 14C , the first roller unit  300  may include two rollers, and the second roller unit  400  may include one roller. 
     In this case, it is preferable that the rollers of the first roller unit  300  be arranged to be in contact with the roller of the second roller unit  400 . It is preferable that the rollers of the first roller unit  300  be spaced apart from each other. 
     In this case, one pair of rollers of the first roller unit  300  are rotated in the same direction by the roller of the second roller unit  400 , thus transmitting contents from the second discharge port  210  to the roller of the second roller unit  400 . 
     Since the first roller unit  300  of  FIG. 14C  includes two rollers, the contents discharged from the second discharge port  210  may be evenly spread over a larger area of the roller of the second roller unit  400 . 
     Further, as shown in  FIG. 14D , the first roller unit  300  may include two rollers, and the second roller unit  400  may include two rollers. 
     In this case, the first and second roller units  300  and  400  may be arranged such that a first roller of the first roller unit  300  makes contact with a first roller of the second roller unit  400 , and a second roller of the first roller unit  300  makes contact with a second roller of the second roller unit  400 . Preferably, the first and second rollers of the first roller unit  300  are spaced apart from each other, and the first and second rollers of the second roller unit  400  are spaced apart from each other. 
     In this case, contents discharged from the second discharge port  210  are applied to the first and second rollers of the first roller unit  300 , so that the contents may be independently transferred to the first and second rollers of the second roller unit  400 . Thus, each roller of the second roller unit  400  may independently perform an application function. 
     Further, as shown in  FIG. 14E , the first roller unit  300  may include three rollers, and the second roller unit  400  may include one roller. 
     In this case, a central roller of the first roller unit  300  makes contact with the roller of the second roller unit  400 . Further, peripheral rollers may be provided on opposite sides of the central roller. The peripheral rollers are spaced apart from the roller of the second roller unit  400 , and make contact with the central roller. 
     In this case, first, liquid contents discharged from the second discharge port  210  are applied to the central roller of the first roller unit  300 , which is placed above the second discharge port  210 . Subsequently, the liquid contents are transferred from the central roller to the peripheral rollers of the first roller unit  300 . Since the central roller makes contact with the peripheral rollers, the liquid contents may be transferred to the second roller unit  400  while being evenly applied over a larger area. 
     Further, as shown in  FIG. 14F , the first roller unit  300  may include three rollers, and the second roller unit  400  may include one roller. 
     Peripheral rollers of the first roller unit  300  are provided on opposite sides of the central roller of the first roller unit  300  in such a way as to make contact with the central roller of the first roller unit  300 . Here, the roller of the second roller unit  400  may be arranged to make contact with the peripheral rollers of the first roller unit  300 . 
     Preferably, the central roller of the first roller unit  300  is spaced apart from the roller of the second roller unit  400 . 
     In this case, first, contents discharged from the second discharge port  210  are applied to the central roller of the first roller unit  300 , which is placed above the second discharge port  210 . Subsequently, the contents are evenly transferred from the central roller to the peripheral rollers which are placed on opposite sides of the central roller, and thereafter are transmitted from the peripheral rollers to the roller of the second roller unit  400 . Such an operation allows the liquid contents to be more evenly spread onto the roller of the second roller unit  400 . 
     Further, as shown in  FIG. 14G , the first roller unit  300  may include three rollers, and the second roller unit  400  may include two rollers. 
     Peripheral rollers of the first roller unit  300  may be provided on opposite sides of the central roller of the first roller unit  300  in such a way that the rollers are spaced apart from each other. Here, first and second rollers of the second roller unit  400  are arranged, respectively, between the central roller and the peripheral rollers of the first roller unit  300 , thus rotating the rollers of the first roller unit  300 . 
     While the central and peripheral rollers of the first roller unit  300  and the first roller of the second roller unit  400 , that is, three rollers, rotate together, liquid contents transferred to the first roller of the second roller unit  400  are more evenly spread. 
     Preferably, the first and second rollers of the second roller unit  400  are spaced apart from each other. 
     The number and arrangement of the first and second roller units  300  and  400  are not limited to the embodiments described and shown herein, and thus may be variously changed. 
       FIG. 15  is an exploded perspective view showing a liquid-material application apparatus according to another embodiment of the present invention. The liquid-material application apparatus will be described with reference to  FIG. 15 . 
     The liquid-material application apparatus according to the present invention includes a body  100 , a first roller support  1100 , a first roller unit  300 , a second roller support  1200 , and a second roller unit  400 . 
     Among the components of the liquid-material application apparatus according to the present invention, the body  100 , the first roller unit  300 , and the second roller unit  400  have been described above. In order to avoid duplicating the description, the description of the body  100 , the first roller unit  300 , and the second roller unit  400  will be skipped. The first and second roller supports  1100  and  1200  will be described below in detail. 
     The first roller support  1100  is placed on the top of the body  100 , and has on its lower surface a second discharge port  210  which communicates with the first discharge port  120 . A concave part  220  is formed in an upper portion of the first roller support  1100  so that the first roller unit  300  is placed therein. The second discharge port  210  is formed to communicate with the concave part  220 . 
     The second roller support  1200  is rotatably coupled with the second roller unit  400 . A slit  1210  is formed through a lower surface of the second roller support  1200  so that a surface of the first roller unit  300  protrudes through the slit  1210  when the second roller support  1200  is coupled to the first roller support  1100 . 
     The second roller unit  400  is coupled to the second roller support  1200  in such a way as to be put in contact with the first roller unit  300  protruding through the slit  1210 . 
     Thus, when the second roller unit  400  rotates, the first roller unit  300  rotates while it is in contact with the second roller unit  400 , so that contents discharged from the second discharge port  210  are transferred to the second roller unit  400 . 
     The above-mentioned first roller unit  300  of the liquid-material application apparatus may comprise a plurality of balls, according to an embodiment. Further, the body  100  may be covered with a cap  700  so as to protect the second roller unit  400 , as shown in  FIGS. 1 to 5  and  FIG. 15 . 
     As described above, a liquid-material application apparatus with a dual roller structure according to the present invention achieves the following effects by interaction between a plurality of rollers. 
     The present invention provides a liquid-material application apparatus, which allows liquid material to be evenly spread over a second roller unit using a first roller unit, thus enabling the liquid material to be evenly applied to a place which is in contact with the second roller unit, such as the skin. 
     The present invention provides a liquid-material application apparatus, which prevents liquid material from adhering to an undesired place during the operation of applying the liquid material. 
     The present invention provides a liquid-material application apparatus, which enables the discharge of liquid material to be easily controlled by rotating to the left or right. 
     The effects of the present invention are not limited to the above-mentioned effects, and other effects which are not mentioned could be clearly understood by those skilled in the art from the description. 
     It is to be understood that the form of the invention herein shown and described above is for illustrative purposes only. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.