Patent Publication Number: US-10774461-B2

Title: Laundry treatment apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. § 119 to Korean Application No. 10-2017-0064246, filed on May 24, 2017, whose entire disclosure is hereby incorporated by reference. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a laundry treatment apparatus. 
     2. Background 
     Generally, washing machines, which sequentially perform washing, rinsing, and spin-drying operations, are typical examples of laundry treatment apparatus. The washing machine may be generally classified as a top-loading washing machine or a front-loading washing machine (also called a drum washing machine). The top-loading washing machine performs washing of the laundry by using a rotating water stream generated in wash water. In contrast, the front-loading washing machine performs washing of the laundry by friction between laundry items that is generated when the laundry items are lifted and dropped by a lifter installed at an inner circumference of a drum. 
     Further, as clothing materials become more high-quality and diverse, there has been an increasing interest in pre-washing laundry. For example, a special detergent is used to remove old, stubborn stains or to wash functional clothing, and pre-washing may be performed in a washing space provided separately from the washing machine prior to the main washing by the washing machine. In addition, after the main washing is performed by the washing machine, drying and ironing of the laundry may occur. 
     However, a pre-washing part, a main washing part, a drying part, and an ironing part may be provided separately in different spaces, such that much time is taken from pre-washing to ironing of the laundry, and the laundry may be moved between the separate spaces when pre-washing, main washing, drying, and ironing of the laundry are performed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein: 
         FIG. 1  is a view illustrating a laundry treatment apparatus according to an embodiment of the present disclosure; 
         FIG. 2  is a perspective view of the pre-washer illustrated in  FIG. 1 ; 
         FIG. 3  is a view illustrating an example where a lid illustrated in  FIG. 2  is opened and a drawer type washer illustrated in  FIG. 2  is drawn out; 
         FIG. 4  is a side cross-sectional view of  FIG. 2 ; 
         FIG. 5  is a partial view of a pre-washer; 
         FIG. 6  is a control block diagram illustrating a pre-washer; 
         FIG. 7  is a flowchart illustrating a method of controlling a pre-washer; 
         FIG. 8  is a cross-sectional view of a main washer illustrated in  FIG. 1 ; 
         FIG. 9  is a perspective view of a drum of the main washer illustrated in  FIG. 8 ; 
         FIG. 10  is a perspective view of a tub of the main washer illustrated in  FIG. 8 ; 
         FIG. 11  is a perspective view of a balancing unit according to an embodiment of the present disclosure; 
         FIG. 12  is block diagram illustrating a main washer according to an embodiment of the present disclosure; 
         FIG. 13  is a diagram illustrating a rotation speed of a drum at the beginning of spin-drying and in the course of spin-drying by a main washer according to an embodiment of the present disclosure; 
         FIG. 14  is a diagram illustrating a process of controlling a balancing unit at the beginning of spin-drying and in the course of spin-drying by a main washer according to an embodiment of the present disclosure; 
         FIG. 15  is a perspective view of a dryer illustrated in  FIG. 1 ; 
         FIG. 16  is an exploded perspective view of the dryer illustrated in  FIG. 15 ; 
         FIG. 17  is a view of the dryer illustrated in  FIG. 15  which is partially cut to show the inside thereof; 
         FIG. 18  is a view illustrating a state where a basket is installed, as seen from a rear side; 
         FIG. 19  is a cross-sectional view illustrating a connection structure of a basket and a casing; 
         FIG. 20  is an enlarged view of portion A illustrated in  FIG. 19 ; 
         FIG. 21  is a detailed view of portion B illustrated in  FIG. 18 ; 
         FIG. 22  is a perspective view illustrating an operation state of an iron part illustrated in  FIG. 1 ; 
         FIG. 23  is a side cross-sectional view of a dehumidifying and ironing module illustrated in  FIG. 22 ; 
         FIG. 24  is a diagram illustrating a dehumidifying unit illustrated in  FIG. 23 ; 
         FIG. 25  is a diagram illustrating a state where a first storage space is opened in the dehumidifying and ironing module illustrated in  FIG. 22 ; 
         FIG. 26  is a diagram illustrating a state where a second storage space is opened in the dehumidifying and ironing module illustrated in  FIG. 22 ; and 
         FIG. 27  is a control block diagram illustrating an ironing part. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a laundry treatment apparatus according to embodiments of the present disclosure will be described with reference to accompanying drawings. 
       FIG. 1  is a view illustrating a laundry treatment apparatus according to an embodiment of the present disclosure. Referring to  FIG. 1 , the laundry treatment apparatus includes a pre-washer (or pre-washing station)  100 , a main washer  200 , a dryer  300 , and an ironing part (or ironing station)  400 . The pre-washer  100 , the main washer  200 , the dryer  300 , and the ironing part  400  may be provided in sequence. For example, the pre-washer  100 , the main washer  200 , the dryer  300 , and the ironing part  400  may be positioned in an order associated with the treatment of the laundry (e.g., first pre-washing, then washing, then drying, and then ironing). 
     In one example, when the pre-washer  100  is provided on the leftmost side, the main washer  200  may be provided on the right side of the pre-washer  100 , the dryer  300  may be provided on the right side of the main washing part  200 , and the ironing part  400  may be provided on the right side of the dryer  300 . Similarly, when the pre-washer  100  is provided on the rightmost side, the main washing part  200  may be provided on the left side of the pre-washer  100 , the dryer  300  may be provided on the left side of the main washing part  200 , and the ironing part  400  may be provided on the left side of the dryer  300 . As the pre-washer  100 , the main washing part  200 , the dryer  300 , and the ironing part  400  are provided in sequence, a user may sequentially perform rough washing, main washing, drying, and ironing at one place. 
     A lid  140 , which rotates with its rear end serving as a center of rotation to be opened and closed upward and downward, may be provided at a top portion of the pre-washer  100 . A sink bowl  120  (see  FIG. 3 ) may be installed at the bottom of the lid  140 . An accommodation space  121  (see  FIG. 3 ), which has an open top portion, may be formed at the sink bowl  120 . Laundry and wash water may be accommodated in the accommodation space  121  for prewashing. 
     The pre-washer  100  may perform pre-washing of the laundry accommodated in the accommodation space  121 . Then, the laundry pre-washed by the pre-washer  100  is inserted into the main washer  200  from the front, so that the main washer  200  may perform main washing, rinsing, and dehydrating of the laundry. Subsequently, the dryer  300  may dry the laundry, which is dehydrated by the main washer  200  and is introduced into the dryer  300  from the front. Then, the ironing part  400  may iron the laundry dried by the dryer  300 . 
     A first upper panel  285  may be provided at a top portion of the main washer  200  and the dryer  300 . A top surface of the first upper panel  285  may be provided at substantially the same height as a top surface of the lid  140 . 
     A second upper panel  411   a  may be provided at a top portion of the dryer  400 . The second upper panel  411   a  may form a top surface of the dryer  400 . The top surface of the second upper panel  411   a  may be provided at substantially the same height as the top surface of the lid  140 . 
     As the top surfaces of the lid  140 , the first upper panel  285 , and the second upper panel  411   a  are provided at substantially the same height, a user may better perceive that the pre-washer  100 , the main washer  200 , the dryer  300 , and the ironing part  400  are integrated as a single element. Furthermore, providing the top surfaces of the lid  140 , the first upper panel  285 , and the second upper panel  411   a  at substantially the same height allows a user to slide laundry across the top surfaces to minimize lifting of the laundry when moving the laundry between the pre-washer  100 , the main washer  200 , the dryer  300 , and the ironing part  400 . 
     A first side panel  170  may be provided at one side of the pre-washer  100 . The first side panel  170  may form one side (e.g., a left side) of the laundry treatment apparatus. Further, a second side panel  470  may be provided at one side (e.g., a right side) of the dryer  400 . The second side panel  470  may form the other side of the laundry treatment apparatus. 
     A first door  280  may be provided at a front portion (or surface) of the main washer  200 . The first door  280  may open and close a front lower side of the first upper panel  285 . Further, a second door  380  may be provided at a front portion of the dryer  300 . The second door  380  may open and close a front lower side of the first upper panel  285 . The first door  280  may be provided on the left side of the second door  380 , and the second door  380  may be provided on the right side of the first door  280 . 
     The first door  280  may have a left end which is rotatably connected to a cabinet  211  of the main washer  200 , so that the first door  280  may be opened and closed back and forth with the left end serving as a center of rotation. Further, the second door  380  may have a right end which is rotatably connected to a casing  310  of the dryer  300 , to be opened and closed back and forth with the right end serving as a center of rotation. 
     Hereinafter, the pre-washer  100 , the main washer  200 , the dryer  300 , and the ironing part  400  each will be described in detail. The pre-washer  100  may be described as follows.  FIG. 2  is a perspective view of the pre-washer  100  illustrated in  FIG. 1 ; and  FIG. 3  is a view illustrating an example where a lid  140  illustrated in  FIG. 2  is opened and a drawer type washer  130  illustrated in  FIG. 2  is drawn out. 
     Referring to  FIGS. 2 and 3 , the pre-washer  100  may include a cabinet  110 , a sink bowl  120 , and a drawer type washer  130 . The cabinet  110  is formed in a rectangular shape having a top surface and a front surface which are open, and a hollow inner space. That is, the cabinet  110  may include a left side panel  111 , a right side panel  112 , a back panel (not shown), a lower panel  113 , and a top panel  119 . Each of the left side panel  111 , the right side panel  112 , the back panel, the lower panel  113 , and the top panel  119  may be formed in a rectangular shape. As used here, directions, such as “left”, “right”, “front”, “back”, top, and bottom, are relative to a user of the installed pre-washer  100 . 
     The left side panel  111  may form a left surface of the cabinet  110 . The right side panel  112  is spaced apart from the left side panel  111 , may be provided facing the left side panel  111 , and may be formed to have the same size as the size of the left side panel  111 , thereby forming a right surface of the cabinet  110 . 
     The lower panel  113  may form a lower surface of the cabinet  110 . Legs (not shown) may protrude downward from the bottom of the lower panel  113 . The legs may be located at each of the four corners of the lower panel  113 , so that the cabinet  110  may be lifted from a ground surface. The height of the legs may be adjusted by a user to balance the cabinet  110 . 
     The top panel  119  may form a top surface of the cabinet  110 . The top panel  119  may have a middle hollow space, at which the sink bowl  120  may be provided. In the top panel  119 , operation parts (or user interfaces)  114 ,  115 ,  116 , and  117  and a display  118  may be provided forward of the sink bowl  120 . The operation parts  114 ,  115 ,  116 , and  117  may be mechanical buttons or touch buttons. In another example, the operation parts  114 ,  115 ,  116 , and  117  may correspond to regions of a touch screen. The operation parts  114 ,  115 ,  116 , and  117  may include a power operation part (or power user interface)  114 , a wash cycle operation part (or wash cycle user interface)  115 , and water supply operation parts (or water supply user interface)  116  and  117 . The display  118  may display, for example, information regarding an operation state of the operation parts  114 ,  115 ,  116 , and  117  and soaking time. 
     The sink bowl  120  may be provided at an open top surface of the cabinet  110 . The sink bowl  120  may have an accommodation space  121  which is provided at an upper portion of the cabinet  110  and is formed in a rectangular shape. The accommodation space  121  may be formed by an open top portion of the sink bowl  120 , and may accommodate laundry and wash water. A user may put the laundry and wash water into the accommodation space  121  at the top of the sink bowl  120 . After the laundry and wash water are introduced into the accommodation space  121 , pre-washing of the laundry may be performed. 
     The accommodation space  121  in the sink bowl  120  may have a front surface which is tilted such that a lower end of the front surface is closer to a rear side of the accommodation space  121  than an upper end of the of the front surface. A plurality of washing ribs  122  may protrude upward from the front surface of the accommodation space  121  of the sink bowl  120 . The plurality of washing ribs  122  may be vertically spaced apart from each other, and may be formed to be horizontally elongated. A user may rub the laundry against the plurality of washing ribs  122  to pre-wash the laundry. 
     A water stream generator (or pump)  123  may be provided on both the left side and the right side of the accommodation space  121  of the sink bowl  120 . Although  FIG. 3  illustrates an example where the water stream generator  123  is provided only on the left side of the accommodation space  121  in the sink bowl  120 , another water stream generator  123  may also be provided on the right side of the accommodation space  121  in the sink bowl  120  at a position corresponding the position of the left side water stream generator  123 . However, a single water stream generator  123  may be provided on one of the left side, the right side, or other portion of the accommodating space  121  of the sink bowl  120 . 
     The water stream generator  123  may generate water stream in wash water accommodated in the accommodation space  121 . As the water stream generator  123  generates water stream in wash water accommodated in the accommodation space  121 , there is no need for a user to perform pre-washing of the laundry by hand; and by simply positioning the laundry in the accommodation space  121 , pre-washing and soaking of the laundry may be performed automatically by the water stream generated by the water stream generator  123 . In one example, the water stream generator  123  may spray air onto the wash water accommodated in the accommodation space  121 , to generate the water stream in the wash water accommodated in the accommodation space  121 . In another example, the water stream generator  123  may include an impeller to generate the water stream in the wash water. 
     A drain hole  124 , through which the wash water accommodated in the accommodation space  121  is drained, may be formed at the bottom surface of the sink bowl  120 . As described herein, the drain hole may be selectively closed during pre-washing to maintain wash water in the accommodation space  121  and may be selectively opened after the pre-washing to remove the wash water. 
     A faucet  125 , which supplies the wash water into the accommodation space  121 , may be installed at the sink bowl  120 . The faucet  125  is connected with a water supply pipe in a building, to supply the wash water into the accommodation space  121 . The faucet  125  may be installed to be movable upward and downward at a rear side of the sink bowl  120 . A faucet receiving groove  126  may be formed at a top rear side of the sink bowl  120 . When the faucet  125  moves upward, the faucet  125  may be withdrawn from the faucet receiving groove  126  to protrude upward from the sink bowl  120 . When the faucet  125  moves downward, the faucet  125  may be received in the faucet receiving groove  126 . After receiving the faucet  125  in the faucet receiving groove  126 , a user may close the lid  140  which will be described later. That is, when the lid  140  is closed, the faucet  125  may be received in the faucet receiving groove  126  and may be provided below the lid  140 . 
     The lid  140 , which opens and closes the open top of the accommodation space  121 , may be provided at the top portion of the cabinet  110 . The water stream generator  123  may generate the water stream in the wash water accommodated in the accommodation space  121 . When the water stream generator  123  generates the water stream in the wash water accommodated in the accommodation space  121 , a user may close the lid  140  so that during the pre-washing process, the wash water accommodated in the accommodation space  121  is not splashed out of the sink bowl  120 . 
     The lid  140  may be formed in a rectangular shape. The lid  140  may include a lid glass  141 , and a lid frame  142  supporting the lid glass  141  by surrounding the edges of the lid glass  142 . The lid glass  141  may be formed in a rectangular shape, and the lid frame  142  may support the lid glass  141  by surrounding the four edges of the rectangular-shaped lid glass  141 . The lid glass  141  may be made of a transparent material. While the lid  140  closes the open top surface of the accommodation space  121 , a user may see the laundry accommodated in the accommodation space  121  through the lid glass  141  from above the lid glass  141 . 
     A rear panel  150  may be provided at the top portion of the cabinet  110 . The rear panel  150  may be provided rearward of the lid  140 . The lid  140  may occupy most of the top surface of the cabinet  110 , and the rear panel  150  may occupy a remaining portion behand the portion occupied by the lid  140 . When the lid  140  closes the open top of the accommodation space  121 , the top surface of the lid  140  and the top surface of the rear panel  150  may be substantially horizontal to each other. A rear end of the lid  140  may be rotatably connected to the rear panel  150 . When the lid  140  is totally open, the rear surface of the lid  140  may come into contact with the top surface of the rear panel  150  to be supported thereby. In this manner, when the lid  140  is totally open, the lid  140  may be supported by the rear panel  150 , thereby remaining open. 
     A drawer  160  may be provided at the open front surface of the cabinet  110 . The drawer  160  may be provided below the sink bowl  120 , and may move inwards and outwards of the cabinet  110 . Left and right sides of the drawer  160  are connected to left and right interior sides of the cabinet  110  to be slidable forward and backward, such that the drawer  160  may move inwards and outwards of the cabinet  110 . A washing detergent or other items may be held in the drawer  160 . 
     The drawer type washer  130  may be provided at the open front surface of the cabinet  110 . The drawer type washer  130  may be provided below the sink bowl  120 . The drawer type washer  130  may be provided below the drawer  160 . The drawer type washer  130  may move inwards and outwards of the cabinet  110 . A rail  131  may be installed on left and right sides of the drawer type washer  130 , and a rail guide (not shown), to which the rail  131  is connected to be slidable forward and backward, may be installed on left and right interior sides of the cabinet  110 , such that the drawer type washer  130  may be move inwards and outwards of the cabinet  110 . Although described as including the drawer type washer  130 , the pre-washer  100  may include a different type of washing machine, such as a front loading washing machine that does not slide inward and outward from the cabinet  100  and includes a front door to providing an opening to receive the laundry from the sink bowl  120 . 
     The drawer type washer  130  may have a structure of a general top-loading washing machine. The drawer type washer  130  may perform washing, rinsing, and spin-drying of the laundry. After pre-washing the laundry in the accommodation space  121  of the sink bowl  120 , a user may insert the pre-washed laundry into the drawer type washer  130  for main washing. 
       FIG. 4  is a side cross-sectional view of the pre-washer  100 . Referring to  FIGS. 3 and 4 , the drawer type washer  130  may include a drawer frame  132 , an outer chamber  133 , and an inner chamber  134 . The drawer frame  132  may form an external appearance of the drawer type washer  130 . The drawer frame  132  may move forward and rearward in the cabinet  110 . The rail  131  may be installed on left and right sides of the drawer frame  132  so that the drawer frame  132  may move forward and rearward in the cabinet  110 . The drawer frame  132  has a cavity, and at least a portion of the drawer from  132  may be drawn in the cabinet  110 , thereby providing a space to receive the outer chamber  133  and the inner chamber  134 . The drawer frame  132  has an open top. 
     A door  135  may be provided at the open top of the drawer frame  132 , to open and close the open top of the drawer frame  132 . A display (not shown), which displays an operation state of the drawer type washer  130 , and a user interface operation part (not shown) may be provided at the front top portion of the drawer frame  132 . 
     The outer chamber  133  is provided in the cavity of the drawer frame  132  and may accommodate wash water. The outer chamber  133  may be formed in a cylindrical shape with an open top portion. 
     The inner chamber  134  is rotatably provided in the outer chamber  133 , and may accommodate the laundry. The inner chamber  134  may be formed in a circle shape with an open top portion. A user may open the door  135  to insert the laundry through the open top of the drawer frame  132 . The laundry inserted through the open top of the drawer frame  132  passes the open top portion of the outer chamber  133  to be accommodated in the inner chamber  134  through the open top portion of the inner chamber  134 . A plurality of through-holes  134   a  may be formed on the circumferential surface of the inner chamber  134 . The wash water accommodated in the outer chamber  133  may be introduced into the inner chamber  134  through the plurality of through-holes  134   a.    
     A pulsator  136  may be rotatably provided on a bottom surface of the inner chamber  134 . When the pulsator  136  rotates, a rotating water stream may be generated in the wash water in the inner chamber  134 . A motor  137  may be provided in the drawer frame  132 , and the motor  137  may be provided at a lower side of the outer chamber  133  in the drawer frame  132 . A rotation axis  137   a  of the motor  137  may be vertically elongated. The rotation axis  137   a  of the motor  137  may vertically penetrate through the bottom surface of the outer chamber  133  and the bottom surface of the inner surface  134 . 
     A clutch  138  may be interposed between the bottom surface of the outer chamber  133  and the pulsator  136 . The clutch  138  may connect at least one of the inner chamber  134  or the pulsator  136  to the rotation axis  137   a  of the motor  137 . When the clutch  138  connects the inner chamber  134  with the rotation axis  137   a  of the motor  137 , the inner chamber  134  may rotate along with the rotation axis  137   a  of the motor  137 . When the clutch  138  connects the pulsator  136  with the rotation axis  137   a  of the motor  137 , the pulsator  136  may rotate along with the rotation axis  137   a  of the motor  137 . When the clutch  138  connects both the inner chamber  134  and the pulsator  136  with the rotation axis  137   a  of the motor  137 , the inner chamber  134  and the pulsator  136  may rotate along with the rotation axis  137   a  of the motor  137 . 
     The faucet  125  may include a horizontal part (or horizontal arm)  125   a  received in the faucet receiving groove  126 , and an extending part (or extending arm)  125   b  which extends downward from the horizontal part  125   a  to be provided rearward of the sink bowl  120 . The faucet  125  may be installed at the sink bowl  120  to be movable upward and downward. When the faucet  125  moves upward, the horizontal part  125   a  may protrude outward from the faucet receiving groove  126 , and when the faucet  125  moves downward, the horizontal part  125   a  may be received in the faucet receiving groove  126 . 
     The extending part  125   b  is tilted with a lower end being closer to a rear side than an upper end. A latch groove  125   e  may be provided on a rear surface of the extending part  125   b . Further, a latch protrusion  151 , which is provided at the rear panel  150 , may latch into the latch groove  125   e  when the faucet  125  protrudes from the faucet receiving groove  126 . For example, when a user opens the lid  140 , and then lifts up the horizontal part  125   a  of the faucet  125 , the latch protrusion  151  may be latched into the latch groove  125   e , such that the faucet  125  may remain protruding from the faucet receiving groove  126 . Further, when the faucet  125  initially protrudes from the faucet receiving groove  126  and then a user presses down the horizontal part  125   a  of the faucet  125 , the faucet  125  may move downward, and the latch protrusion  151  may be released from the latch groove  125   e , such that the horizontal part  125   a  of the faucet  125  may be received in the faucet receiving groove  126 . In one example, the latch protrusion  151  may be made of an elastic, deformable material to conform to the latch groove  125   e.    
     The latch groove  125   e  may include a first latch groove  125   c , and a second latch groove  125   d  which is provided below the first latch groove  125   c . When the latch groove  125   e  includes the first latch groove  125   c  and the second latch groove  125   d , a protruding height of the faucet  125 , which protrudes upward from the sink bowl  120 , may be adjusted. 
       FIG. 5  is a partial schematic view of the pre-washer  100 . Referring to  FIG. 5 , the faucet  125  may be connected to the water supply passages  171  and  172 . The water supply passages  171  and  172  may supply wash water to the faucet  125 . The water supply values  173  and  174  may open and close the water supply passages  171  and  172 . When the water supply valves  173  and  174  are open, the faucet  125  may supply the wash water, received from the water supply passages  171  and  172 , to the accommodation space  121  of the sink bowl  120 . 
     The water supply passages  171  and  172  may include a cold water passage  171  and a hot water passage  172 . The cold water passage  171  may supply cold water (e.g., water at ambient temperature) to the faucet  125 , and the hot water passage  172  may supply hot water (e.g., water warmed above ambient temperature) to the faucet  125 . 
     The water supply valves  173  and  174  may include a cold water valve  173  and a hot water valve  174 . The cold water valve  173  may be installed at the cold water passage  171 , and the hot water valve  174  may be installed at the hot water passage  172 . The cold water valve  173  may open and close the cold water passage  171 , and the hot water valve  174  may open and close the hot water passage  172 . When the cold water valve  173  is opened, the faucet  125  may supply cold water, supplied from the cold water passage  171 , to the accommodation space  121  of the sink bowl  120 . When the hot water valve  174  is opened, the faucet  125  may supply hot water, supplied from the hot water passage  172 , to the accommodation space  121  of the sink bowl  120 . 
     The sink bowl  120  may be connected to a drain passage  181 . The drain passage  181  may drain wash water in the accommodation space  121  of the sink bowl  120 . The drain passage  181  may be located at a position corresponding to the drain hole  124  from below the bottom of the sink bowl  120 . The drain passage  181  may be provided with a drain valve  182 . The drain valve  182  may selectively open and close the drain passage  181 . When the drain valve  182  is opened, wash water in the accommodation space  121  of the sink bowl  120  may be drained to the outside through the drain passage  181 . The drain passage  181  may further include a drain pump  183 . The drain pump  183  may be activated to suction the wash water in the drain passage  181  and direct the water to the outside. The drain pump  183  may selectively operate while the drain valve  182  is opened to suction the wash water in the drain passage  181  to drain the wash water to the outside. 
       FIG. 6  is a control block diagram illustrating components of the pre-washer  100 . Referring to  FIG. 6 , the pre-washer  100  may further include a controller  190 . Once a water supply signal is received from water supply operation parts  116  and  117 , the controller  190  may open the water supply valves  173  and  174 . 
     As previously described, the water supply operation parts  116  and  117  may be mechanical buttons or touch buttons. For example, when pressed or touched once by a user (or other specific user input is provided), the water supply operation parts  116  and  117  may generate the water supply signal, and the generated water supply signal may be inputted to the controller  190 . Further, when being pressed or touched once again by a user (or other specific user input is provided), the water supply operation parts  116  and  117  may generate a water cut-off signal, and the generated water cut-off signal may be input to the controller  190 . Upon receiving the water supply signal from the water supply operation parts  116  and  117 , the controller  190  opens one or more of the water supply valves  173  and  174 , and upon receiving the water cut-off signal from the water supply operation parts  116  and  117 , the controller  190  closes the opened one or more of the water supply valves  173  and  174 . When one or more of the water supply valves  173  and  174  are opened, the faucet  125  may supply wash water to the accommodation space  121  of the sink bowl  120 , and when the opened one or more of the water supply valves  173  and  174  are closed, the faucet  125  may cut off a supply of the wash water to the accommodation space  121  of the sink bowl  120 . 
     The water supply operation parts  116  and  117  may include, for example, a cold water supply operation part  116  and a hot water supply operation part  117 . When being pressed or touched once by a user (or other particular user input is detected), the cold water supply operation part  116  generates a cold water supply signal, and the generated cold water supply signal is input to the controller  190 . Upon receiving the cold water supply signal from the cold water operation part  116 , the controller  190  opens the cold water valve  173 , to allow the faucet  125  to supply cold water to the accommodation space  121  of the sink bowl  120 . When being pressed or touched once again by a user (or other particular user input is detected), the cold water supply operation part  116  generates a cold water cut-off signal, and the generated cold water cut-off signal is input to the controller  190 . Upon receiving the cold water cut-off signal from the cold water supply operation part  116 , the controller  190  closes the cold water valve  173 , so as to stop the faucet  125  from supplying cold water to the accommodation space  121  of the sink bowl  120 . 
     Further, when being pressed or touched once by a user (or other particular user input is detected), the hot water supply operation part  117  generates a hot water supply signal, and the generated hot water supply signal is inputted to the controller  190 . Upon receiving the hot water supply signal from the hot water supply operation part  117 , the controller  190  opens the hot water valve  174  to allow the faucet  125  to supply hot water to the accommodation space  121  of the sink bowl  120 . When being pressed or touched once again by a user (or other particular user input is detected), the hot water supply operation part  117  generates a hot water cut-off signal, and the generated hot water cut-off signal is inputted to the controller  190 . Upon receiving the hot water cut-off signal from the hot water supply operation part  117 , the controller  190  closes the hot water valve  174  so as to stop the faucet  125  from supplying hot water to the accommodation space  121  of the sink bowl  120 . 
     Upon receiving a wash cycle signal from the wash cycle operation part  115 , the controller  190  operates the water stream generator  123  for a predetermined period of time, and after the predetermined period of time, stops the water stream generator  123  and opens the drain valve  182 . Accordingly, decoloring and damage of the laundry, which is caused by excessive pre-washing and soaking of the laundry, may be prevented. When the drain passage  181  includes both the drain valve  182  and the drain pump  183 , upon receiving a wash cycle signal from the wash cycle operation part  115 , the controller  190  operates the water stream generator  123  for a predetermined period of time, and after the predetermined period of time, stops the water stream generator  123  to open the drain valve  182  and operate the drain pump  183  to drain the wash water. 
     The wash cycle operation part  115  may be a mechanical button or a touch button. The wash cycle signal may include a first wash cycle signal and a second wash cycle signal. That is, when pressed or touched once by a user (or other particular user input is detected), the wash cycle operation part  115  may generate the first wash cycle signal, and the generated first wash cycle signal may be input to the controller  190 . When pressed or touched once again by a user (or other particular user input is detected), the washing cycle operation part  115  may generate the second wash cycle signal, and the generated second wash cycle signal may be input to the controller  190 . 
     Upon receiving the first wash cycle signal from the wash cycle operation part  115 , the controller  190  operates the water stream generator  123  for a first predetermined period of time, and after the first period of time, stops the water stream generator  123  and opens the drain valve  182  to remove the wash water. When the drain passage  181  includes the drain valve  182  and the drain pump  183 , upon receiving the first wash cycle signal from the wash cycle operation part  115 , the controller  190  operates the water stream generator  123  for the first predetermined period of time, and after the first period of time, stops the water stream generator  123 , to open the drain valve  182  and operate the drain pump  183  to drain the wash water. 
     Further, upon receiving the second wash cycle signal from the wash cycle operation part  115 , the controller  190  operates the water stream generator  123  for a second predetermined period of time, and after the second period of time the water stream generator  123  and opens the drain valve  182  to remove the wash water. When the drain passage  181  includes the drain valve  182  and the drain pump  183 , upon receiving the second wash cycle signal from the wash cycle operation part  115 , the controller  190  operates the water stream generator  123  for the second predetermined period of time, and after the second period of time, stops the water stream generator  123 , opens the drain valve  182 , and operates the drain pump  183 . 
     The second predetermined period of time may be different from, and may be shorter than, the first predetermined period of time. When wash water, which is accommodated in the accommodation space  121  of the sink bowl  120 , is cold water, a user may operate the wash cycle operation part  115  to generate the first wash cycle signal. Further, when the wash water, which is accommodated in the accommodation space  121 , is hot water, a user may operate the wash cycle operation part  115  to generate the second wash cycle signal. 
       FIG. 7  is a flowchart illustrating a method of controlling a pre-washer. Here, the method of controlling the pre-washer will be described in connection with the operation of the pre-washer. Referring to  FIG. 7 , upon opening the lid  140  and putting the laundry into the accommodation space  121  of the sink bowl  120 , a user may operate the water supply operation units  116  and  117  to generate a water supply signal. Then, the water supply signal generated by the water supply operation units  116  and  117  is inputted to the controller  190  in S 1 . When the user opens the lid  140 , inserts the laundry into the accommodation space  121  of the sink bowl  120 , and operates the cold water operation part  116 , a cold water signal is generated, and the cold water signal generated by the cold water operation part  116  is inputted to the controller  190 . Further, when the user opens the lid  140 , inserts the laundry into the accommodation space  121  of the sink bowl  120 , and operates the hot water operation part  117 , a hot water signal is generated, and the hot water signal generated by the hot water operation part  116  is inputted to the controller  190 . 
     Upon receiving the water supply signal from the water supply operation parts  116  and  117 , the controller  190  opens the water supply valves  173  and  174  in S 2 . For example, upon receiving the cold water signal from the cold water operation part  116 , the controller  190  opens the cold water valve  173 , and upon receiving the hot water signal from the hot water operation part  117 , the controller  190  opens the hot water valve  174 . 
     Once wash water is filled to a desired level in the accommodation space  121  of the sink bowl  120 , a user may operate the water supply operation parts  116  and  117  again to generate a water cut-off signal. Then, the water cut-off signal generated by the water supply operation parts  116  and  117  is input to the controller  190  in S 3 . In another example, the water cut-off signal is automatically sent after a prescribed time period or after a prescribed amount of wash water is supplied to the accommodation space  121 . 
     Upon receiving the water cut-off signal from the water supply operation parts  116  and  117 , the controller  190  closes the water supply valves  173  and  174  in S 4 . Then, a user operates the wash cycle operation part  115  to generate a wash cycle signal, and may further close the lid  140 . Then, the wash cycle signal generated by the wash cycle operation part  115  is input to the controller  190  in S 5 . Upon receiving the wash cycle signal from the wash cycle operation part  115 , the controller  190  activates the water stream generator  123  in S 6  to form a water stream in the wash water to pre-wash the laundry. 
     Then, the controller  190  determines whether the operation time of the water stream generator  123  is equal to or greater than a predetermined period of time in S 7 . When the operation time of the water stream generator  123  is less than the predetermined period of time, the controller  190  continues to operate the water stream generator  123  in S 6 . When the operation time of the water stream generator  123  is greater than the predetermined period of time, the controller  190  stops the water stream generator  123 , opens the drain valve  182 , and operates the drain pump  183  in S 8  to remove the wash water from the accommodation space  121 . 
     The main washer  200  will be described below.  FIG. 8  is a cross-sectional view of a main washer illustrated  200 ;  FIG. 9  is a perspective view of a drum  224  of the main washer  200 ; and  FIG. 10  is a perspective view of a tub  222  of the main washer  200 . 
     Referring to  FIGS. 8 to 10 , the main washer  200  may include a cabinet  211  which forms an external appearance of the main washer; a door  212  which opens and closes one side of the cabinet  211  so that laundry may be put into the cabinet  211 ; a tub  222  which is provided in the cabinet  211  and is supported by the cabinet  211 ; a drum  224  which is provided in the tub  222  and rotates when the laundry is put; a drum motor  213  which provides torque to the drum  224  to rotate the drum  224 ; a detergent box  233  in which detergent is held; a control panel  214  which receives a user&#39;s input and displays status of a washing machine. 
     The cabinet  211  includes a laundry inlet hole  211   a , through which laundry is put into the cabinet  211 . The door  212  is rotatably connected with the cabinet  211  to open and close the laundry inlet hole  211   a . The cabinet  211  is provided with the control panel  214 . The cabinet  211  is provided with the detergent box  233 , which is retractable. 
     A spring  215  and a damper  217  are provided in the cabinet  211  to absorb shock of a movement of the tub  222  during operation of the washer  200 . The tub  222  contains the wash water. The tub  222  is provided outside the drum  224  to surround the drum  224 . 
     The tub  222  include: a tub main body  222   a  which has a cylindrical shape and both ends of which are open; a front tub cover  222   b  which has a ring shape and is provided at a front side of the tub main body  222   a ; a rear tub cover  222   c  which has a disc shape and is provided at a rear side of the tub main body  222   a . Hereinafter, the front side refers to the side of the door  212 , and the rear side refers to the side of the drum motor  213 . A tub hole  222   d  is formed at the front tub cover  222   b . The tub hole  222   d  is formed to communicate with the laundry inlet  211   a  so that the laundry may be put into the drum  224 . 
     The drum motor  213  is provided at the rear tub cover  222   c  to generate torque. The drum motor  213  is connected with a rotation axis  216  to rotate the drum  224 . The drum motor  213  may rotate the drum  224  at various speeds and directions. The drum motor  213  typically includes: a stator (not shown) wound with a coil; and a rotor (not shown) which rotates by generating electromagnetic interaction with the coil. 
     The rotation axis  216  connects the drum motor  213  with the drum  224 . The rotation axis  216  transfers torque to the drum  244  to rotate the drum  224 . One end of the rotation axis  216  is connected to the center of rotation at the rear side of the drum  224 , and the other end of the rotation axis  216  is connected with the rotor (not shown) of the drum motor  213 . 
     Laundry is received in the drum  224 , and the drum  224  rotates within the tub  222  to move the laundry relative to the wash water. The drum  224  is provided in the tub  222 . The drum  224  is formed in a cylindrical shape and is rotatable. The drum  224  has a plurality of through-holes through which wash water may pass. The drum  224  rotates by receiving the torque from the drum motor  213 . 
     A drum hole  224   a  is provided at a front side of the drum  224 . The drum hole  224   a  is formed to communicate with the laundry inlet hole  211   a  and the tub hole  222   d  to provide a passage through which the laundry is inserted into the drum  224 . A front guide rail  225  is connected to a front circumference of the drum  224 , and a rear guide rail  226  is connected to a rear circumference of the drum  224 . 
     A gasket  228  seals a space between the tub  222  and the cabinet  211 . The gasket  228  may be interposed between the opening of the tub  222  and the laundry inlet hole  211   a . The gasket  228  absorbs shock delivered to the door  212  when the drum  224  rotates, and prevents wash water in the tub  222  from leaking to the outside. The gasket  228  may be provided with a circulation nozzle  227  which sprays wash water into the drum  224 . 
     The detergent box  233  may hold a detergent, a fabric softener, bleach, and the like. The detergent box  233  is retractable at the front surface of the cabinet  211 . When wash water is supplied, the detergent in the detergent box  233  is mixed with the wash water to be introduced into the tub  222 . 
     The cabinet  211  may include a water supply valve  231  which adjusts introduction of the wash water supplied from an external water source. The cabinet  211  may also include a water supply passage  232  through which the wash water, introduced into the water supply valve, flows to the detergent box  233 , and a water supply pipe  234  through which the wash water, mixed with the detergent in the detergent box  233 , is introduced into the tub  222 . 
     The cabinet  211  may further includes a drain pipe  235  through which the wash water in the tub  222  is drained; a pump  236  which discharges the wash water in the tub  222 , and a circulation passage  237  which circulates the wash water. The cabinet  211  may also include a circulation nozzle  227  which introduces the wash water is into the drum  224 ; and a drain passage  238  through which the wash water is drained to the outside. Depending on embodiments, the pump  236  may include a circulation pump and separate a drain pump which may be connected to the circulation passage  237  and the drain passage  238  respectively. 
     The drain pipe  235  may be include a water level sensor  221  which senses the level of wash water contained in the tub  222 . The water level sensor  221  may be implemented in various manners. In the embodiment, the level of water is measured by changing a space between electrodes by using air pressure changed according to the level of wash water, and by using a change in capacitance of the electrodes. 
     A plurality of front balancing units (or front weights)  210  move along the front guide rail  225  of the drum  224 , and a plurality of rear balancing units (or rear weights)  220  move along the rear guide rail  226  of the drum  224 , so as to change the center of gravity of the drum  224 . In this case, the center of gravity of the drum  224  does not refer to the center of mass of the drum  224  itself, but refers to a common center of gravity of objects, including the drum  224 , the laundry which is put in the drum  224 , the front guide rail  225 , the rear guide rail  226 , the plurality of front balancing units  210 , the plurality of rear balancing units  220 , and other elements attached to the drum  224 , which rotate along with the drum  224  when the drum  224  rotates. 
     The plurality of front balancing units  210  move along a circumference at a front side of the drum  224 , and the plurality of rear balancing units  220  move along a circumference at a rear side of the drum  224 , thereby adjusting the center of gravity of the drum  224  when laundry leans to one side. When the drum  225  rotates with the laundry accumulated at one side, vibration and noise may be caused by this imbalance in which a geometrical center of the rotation axis  216  (the center of gravity) of the drum  224  does not coincide with a real center of gravity of the drum  224  due to the location of the laundry. The plurality of front balancing units  210  and the plurality of rear balancing units  220  cause the center of gravity of the drum  224  to be close to the rotation axis  216 , to reduce the imbalance of the drum  224 . In one embodiment, the plurality of front balancing units  210  correspond to two units of a first front balancing unit  210   a  and a second front balancing unit  210   b ; and the plurality of rear balancing units  220  correspond to two units of a first rear balancing unit  220   a  and a second rear balancing unit  220   b.    
     The plurality of front balancing units  210  move actively along the front guide rail  225 , and the plurality of rear balancing units  220  move actively along the rear guide rail  226 . The active movement refers to movement of the plurality of front balancing units  210  or the plurality of rear balancing units  220  along the front guide rail  225  or the rear guide rail  226  by using their own power. For example, the front balancing units  210  may slide along the front guide rail  225 , and the plurality of rear balancing units  220  may slide along the rear guide rail  226 . 
     The front guide rail  225  is a passage where the plurality of front balancing units  210  move, and the rear guide rail  226  is a passage where the plurality of rear balancing units  220  move. The front guide rail  225  is formed in a ring shape and is connected to a front end circumference of the drum  224 , and the rear guiderail  226  is formed in a ring shape and is connected to a rear end circumference of the drum  224 . The front guide rail  225  and the rear guide rail  226  each may have protrusions so that the plurality of front balancing units  210  and the plurality of rear balancing units  220  may not be separated therefrom. The front guide rail  225  is provided with a front guide rail wire  225   a  to supply power to the plurality of front balancing units  210 , and the rear guiderail  226  is provided with a rear guide rail wire  226   a  to supply power to the plurality of rear balancing units  220 . The front guide rail wire  225   a  and the rear guide rail wire  226   a  are connected to power supplied from an external source. 
     The tub  222  is provided with a plurality of vibration sensors  229  to sense a vibration amount of the tub  222 . The vibration caused by the imbalance of the drum  224  is transmitted by the rotation axis  216  to the tub  222 , causing vibration of the tub  222 . The plurality of vibration sensors  229  may sense the amount of the vibration to measure a degree of imbalance of the drum  224 . 
     The plurality of vibration sensors  229  may be implemented by various sensors which sense the vibration amount of the tub  222 . In one embodiment, the plurality of vibration sensors  229  may include a light sensor which is provided in the tub main body  222   a  and measures a distance between the tub  222  and the cabinet  211 . In the embodiment, the plurality of vibration sensors  229  sense the vibration amount by using a change of distance between the cabinet  211  and the tub  222 . In one configuration (see  FIG. 9 ), the plurality of vibration sensors  229  may include a front vibration sensor  229   a  which is provided at a front side of the tub main body  222   a  and measures a front vibration amount corresponding to an amount of vibration at the front side of the tub  222 ; and a rear vibration sensor  229   b  which is provided at a rear side of the tub main body  222   a  and measures a rear vibration amount corresponding to the amount of vibration at the rear side of the tub  222 . 
     The control panel  214  may include: an input part (not shown), which receives input of wash cycles selected by a user, or input of various operation commands such as operation time and reservation of wash cycles, and the like; and a display (not shown) which displays operation state of the main washer  200 . 
       FIG. 11  is a perspective view of a balancing unit according to an embodiment of the present disclosure. Referring to  FIG. 11 , the plurality of front balancing units  210  and the plurality of rear balancing units  220  may each include a frame body  201 , a body  202 , a wheel  203 , a motor  204 , a contact terminal  205 , and a brake  206 . 
     The frame body  201  forms the frame of each of the plurality of front balancing units  210  and the plurality of rear balancing units  220 , and the wheel  203 , the body  202 , the motor  204 , and the like are connected thereto. The frame body  201  may be formed in a desired shape according to the shape of the front guide rail  225  or the rear guide rail  226 . 
     The body  202  may have a weight suitable to serve as a mass body. According to certain embodiments, the wheel  203  rolls along the front guide rail  225  or the rear guide rail  226  so that the plurality of front balancing units and the plurality of rear balancing units  220  may move relatively smoothly. The wheel  203  may be made of a material having a large frictional force, such as a rubber, so that the wheel  203  may not slide from the front guide rail  225  or the rear guide rail  226 . The wheel  203  rotates by the motor  204 . Depending on embodiments, the wheel  203  may be replaced with a gear, such as a pinion gear or a worm gear. Further, when the wheel  203  is replaced with a gear, the front guide rail  225  or the rear guide rail  226  may include a rack gear or a worm wheel. 
     The motor  204  rotates the wheel  203 . The motor  204  is supplied with power from the contact terminal  205  to generate torque. The contact terminal  205  contacts the front guide rail wire  225   a  or the rear guide rail wire  226   a  to transmit power supplied from an external force to the motor  204 . In one example, the contact terminal  205  is made of a metal material having a small frictional force, so that the contact terminal  205  remains in contact with the front guide rail wire  225   a  or the rear guide rail wire  226   a  without loss of power. 
     The brake  206  allows each of the plurality of front balancing units  210  and the plurality of rear balancing units  220  to halt at a certain position of the guide rail  225 . As the front guide rail  225  or the rear guide rail  226  rotates along with the drum  224 , the brake  206  operate in order to prevent free rotation of each of the plurality of front balancing units  201  and the plurality of rear balancing units  220 . The brake  206  applies a frictional force to the front guide rail  225  or the rear guide rail  226  to fix the plurality of front balancing units  210  and the plurality of rear balancing units  220  to the front guide rail  225  or the rear guide rail  226  respectively. As described herein, the brake  206  applies the frictional force to the front guide rail  225  or the rear guide rail  226  to fix the plurality of front balancing units  210  and the plurality of rear balancing units  220  at positioned to counter a detected imbalance. 
       FIG. 12  is block diagram of the main washer  200  according to an embodiment of the present disclosure. Referring to  FIG. 12 , a controller  290  controls an overall operation of the main washer  200  according to operation commands received by the control panel  214 . The controller  290  may include a microcomputer, a storage device, and other electronic components which control the operation of the main washer  200 . According to wash cycles selected by a user, the controller  290  controls the water supply valve  231 , the drum motor  213 , and the pump  236  by determining whether to perform each cycle or whether to perform operations of water supply, washing, rinsing, drainage, spin-drying, drying, and the like in each cycle, operation time, the number of repeating operations, and the like. Based on the amount of laundry which is the weight of laundry measured at the initial stage of washing, and the water level of the tub  222  that is measured by the water level sensor  221 , the controller  290  controls the water supply valve  231 , the drum motor  213 , and the pump  236 . Additionally, based on the vibration amount of the tub  222  that is measured by the front vibration sensor  229   a  and the rear vibration sensor  229   b , the controller  290  controls the first front balancing unit  210   a , the second front balancing unit  210   b , the first rear balancing unit  220   a  and the second rear balancing unit  220   b.    
       FIG. 13  is a diagram illustrating a rotation speed of a drum  224  at the beginning of spin-drying and in the course of spin-drying by the main washer  200 , and  FIG. 14  is a diagram illustrating a process of controlling a balancing unit  210   a ,  210   b  at the beginning of spin-drying and in the course of spin-drying by the main washer  200 . 
     The controller  290  performs rinsing in S 201  by controlling the drum motor  213  to rotate the drum  224  in one direction so that after laundry is lifted, the laundry is separated from an inner circumference of the drum  224  and is dropped. The rinsing is a process of rotating the drum  224  at a rotational speed with centrifugal force being equal to or less than 1G to remove remaining detergent and contaminants of the laundry. The controller  290  controls the pump  236  to circulate wash water contained in the tub  222  and spray the wash water into the drum  224  through the circulation nozzle  227 . During the rinsing process, the controller  290  controls the drum motor  213  so that the drum  224  rotates, for example, at 46 RPM for a predetermined period of time, stops rotating, and then rotates again at 46 RPM. 
     In the final stage of rinsing, the controller  290  may direct a motion of the first front balancing unit  210   a  and/or the second front balancing unit  210   b , so that an angle between the first front balancing unit  210   a  and the second front balancing unit  210   b  becomes substantially 180 degrees with respect to the center of rotation of the drum  224 , and the controller  290  may manage a movement of the first rear balancing unit  220   a  and/or the second rear balancing unit  220   b , so that an angle between the first rear balancing unit  220   a  and the second rear balancing unit  220   b  becomes substantially 180 degrees with respect to the center of rotation of the drum  224  in S 202 . In this case, the controller  290  continues the rinsing process by controlling the drum motor  210 , so that the drum  224  repeatedly rotates at 46 RPM, which is a rotational speed with centrifugal force being equal to or less than 1G, for a predetermined period of time, stops rotating, and then rotates again at 46 RPM. 
     Thus, by the control of the controller  290 , at least one of the first front balancing unit  210   a  and the second front balancing unit  210   b  may move along the front guide rail  225 , so that the included angle therebetween becomes substantially 180 degrees with respect to the center (C) of rotation of the drum  224 , as illustrated in section (a) of  FIG. 14 . Similarly, by the control of the controller  290 , at least one of the first rear balancing unit  220   a  and the second rear balancing unit  220   b  may move along the rear guide rail  226  so that the included angle therebetween becomes substantially 180 degrees with respect to the center (C) of rotation of the drum  224  as illustrated in (a) of  FIG. 14 . 
     In this example, the controller  290  manages the included angle between the first front balancing unit  210   a  and the second front balancing unit  210   b  to both correspond to 180 degrees, and manages the included angle between the first rear balancing unit  220   a  and the second rear balancing unit  220   b  to be approximately 180 degrees, so that imbalance caused by the plurality of front balancing units  210  and the plurality of rear balancing units  220  may be minimized during a first rough balancing, which will be described later. 
     After the rinsing in S 201  and S 202 , the controller  290  operates the pump  236  to drain the wash water contained in the tub  222  through the drain passage  238  in S 203 . The controller  290  controls the drum motor  213  during the drainage to repeat acceleration and deceleration of the drum  224 . When the water level of the tub  222 , which is measured by the water level sensor  221 , is sufficiently lowered to a level for spin-drying, the controller  290  stops the operation of the pump  236  and stops drainage. 
     After the drainage in S 203 , the controller  290  controls the drum motor  213  to repeat acceleration and deceleration of the drum  224 , and senses a vibration amount of the tub  222  through the front vibration sensor  229   a  and/or the rear vibration sensor  229   b  in S 204 . The controller  290  distributes the laundry by controlling the drum motor  213  to repeat acceleration and deceleration of the drum  224  at a rotational speed (e.g., 80 RPM) at which the laundry starts to cling to the inner circumference of the drum  224 . The distribution of laundry is performed by accelerating the drum  224  to the speed of rotation with centrifugal force being about 1 G, and then decelerating the drum  224 , so that the laundry may be uniformly distributed without leaning to one side. 
     The front vibration sensor  229   a  and/or the rear vibration sensor  229   b  measure the vibration amount of the tub  222  when the drum  224  is repeatedly accelerated and decelerated. When the vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a  and/or the rear vibration sensor  229   b , is greater than a predetermined vibration amount for entry into a spin-drying process, the controller  290  continues distribution of laundry by repeating acceleration and deceleration of the drum  224 . When the vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a  and/or the rear vibration sensor  229   b , does not exceed the predetermined vibration amount for entry into a spin-drying process, the controller  290  proceeds to a next process. 
     Generally, the laundry leans to a rear side of the drum  224 , such that the rear vibration amount of the tub  222  is greater than the front vibration amount thereof. In the embodiment, when the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed the predetermined vibration amount for entry into a spin-drying process, the controller  290  proceeds to the following process. 
     The controller  290  performs first rough balancing in S 205  by controlling the drum motor  213  to rotate the drum  224  at the speed of rotation at which the laundry starts to cling to the inner circumference of the drum  224  (e.g., 80 RPM), and by controlling the plurality of front balancing units  210  and the plurality of rear balancing units  220 . During the first rough balancing in S 205 , the controller  290  may operate the pump  236  to drain the wash water contained in the tub  222  to the outside through the drain passage  238 . The controller  290  may further control the drum motor  213  to rotate the drum  224  while maintaining the rotation speed at 80 RPM or other speed of rotation at which the centrifugal force is about 1G. When the drum  224  rotates while maintaining the rotation speed at 80 RPM during the first rough balancing, the controller  290  performs direct balancing by controlling the plurality of front balancing units  210  and the plurality of rear balancing units  220 . 
     The direct balancing in S 205  is performed by moving the plurality of front balancing units  210  so that the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , may not exceed a predetermined front vibration amount of the first rough balancing; and by moving the plurality of rear balancing units  220  so that the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   a , may not exceed a predetermined rear vibration amount of the first rough balancing. In certain examples, the predetermined rear vibration amount of the first rough balancing in S 205  may be greater than the predetermined front vibration amount of the first rough balancing. 
     Hereinafter, the direct balancing will be described with reference to sections (b) and (c) of  FIG. 14  by using the plurality of front balancing units  210  as an example. As illustrated in section (b) of  FIG. 14 , the controller  290  moves the first front balancing unit  210   a  and the second front balancing unit  210   b  in the same rotational direction. The controller  290  moves the first front balancing unit  210   a  and the second front balancing unit  210   b  in the same rotational direction until the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , is reduced. When the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , is increased, the controller  290  moves the first front balancing unit  210   a  and the second front balancing unit  210   b  in the same opposite rotational direction. The controller  290  stops the movement of the first front balancing unit  210   a  and the second front balancing unit  210   b  at a point where the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , is minimized. 
     The controller  290  may direct motions of the first front balancing unit  210   a  and the second front balancing unit  210   b  in the same rotational direction to minimize the front vibration amount of the tub  222  that is measured by the front vibration sensor  229   a , and then causes the first front balancing unit  210   a  and the second front balancing unit  210   b  to move in different directions as illustrated in (c) of  FIG. 14 . The controller  290  causes the first front balancing unit  210   a  and the second front balancing unit  210   b  to move in a direction where the included angle between the first front balancing unit  210   a  and the second front balancing unit  210   b  based on the center (C) of rotation of the drum  224  is narrowed until the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , is reduced. When the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , is increased, the controller  290  directs the first front balancing unit  210   a  and the second front balancing unit  210   b  to move in a direction where the included angle between the first front balancing unit  210   a  and the second front balancing unit  210   b  is widened. The controller  290  stops the movement of the first front balancing unit  210   a  and the second front balancing unit  210   b  at a point where the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , is minimized. 
     The controller  290  repeats controlling motions of the first front balancing unit  210   a  and the second front balancing unit  210   b  in different rotational directions to minimize the front vibration amount of the tub  222  that is measured by the front vibration sensor  229   a , and then controlling motions of the first front balancing unit  210   a  and the second front balancing unit  210   b  in the same rotational direction again to minimize the front vibration amount of the tub  222  that is measured by the front vibration sensor  229   a.    
     The controller  290  repeats the process of controlling motions of the plurality of front balancing units  210  in the same rotational direction and in different rotational directions until the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , becomes equal to or smaller than the predetermined front vibration amount of the first rough balancing. 
     During the direct balancing, the controller  230  performs the above-described process for the first rear balancing unit  220   a  and the second rear balancing unit  220   b . That is, the controller  290  repeats controlling the motions of the plurality of rear balancing units  220  in the same rotational direction and in different rotational directions until the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , becomes equal to or smaller than the predetermined rear vibration amount of the first rough balancing. 
     During the direct balancing, the controller  290  may first perform direct balancing for the plurality of rear balancing units  220 , and may then perform direct balancing for the plurality of the front balancing units  210 . As described above, the rear vibration amount of the tub  222  tends to be greater than the front vibration amount of the tub  222 , such that the controller  290  may first perform direct balancing for the plurality of rear balancing units  220 , and may then perform direct balancing for the plurality of the front balancing units  210 . 
     When the controller  290  performs direct balancing for the plurality of front balancing units  210  upon completing direct balancing for the plurality of rear balancing units  220 , the rear vibration amount of the tub  222  may be increased due to movement of the plurality of front balancing units  210 . Accordingly, the controller  290  may repeatedly perform direct balancing for the plurality of rear balancing units  220  and direct balancing for the plurality of front balancing units  210 . 
     After the controller  290  completes direct balancing for any balancing units, i.e., either the plurality of front balancing units  210  or the plurality of rear balancing units  220 , when the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , is greater than the predetermined front vibration quantity of the first rough balancing or when the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , is greater than the predetermined rear vibration amount of the first rough balancing, the controller  290  performs direct balancing for the other balancing units. That is, upon completing a direct balancing of any balancing units, i.e., either the plurality of front balancing units  210  or the plurality of rear balancing units  220 , when the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a  is equal to or smaller than the predetermined front vibration amount of the first rough balancing, and when the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , is equal to smaller than the predetermined rear vibration quantity of the first rough balancing, the controller  290  stops repeating the direct balancing for the plurality of rear balancing units  220  and the direct balancing for the plurality of front balancing units  210 . 
     While the controller  290  is performing the direct balancing for the plurality of rear balancing units  220  and the direct balancing for the plurality of front balancing units  210 , and the direct balancing is repeated three times or more, the controller  290  may controls the drum motor  213  to halt the drum  224  and performs distribution of laundry. 
     When the direct balancing in S 205  is successful and both the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed the predetermined rear vibration amount of the first rough balancing, and the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , does not exceed the predetermined front vibration amount of the first rough balancing, the controller  290  accelerates the drum  224  to proceed to a next process. 
     The controller  290  performs second rough balancing in S 206  by controlling the drum motor  213  to rotate the drum  224  at a speed of rotation at which laundry clings to the inner circumference of the drum  224  while rotating (e.g., 190 RPM), and by controlling the plurality of front balancing units  210  and the plurality of rear balancing units  220 . During the second rough balancing in S 206 , the controller  290  operates the pump  236  to drain the wash water contained in the tub  222  to the outside through the drain passage  238 . The controller  290  controls the drum motor  213  so that the drum  224  may rotate while maintaining the speed of rotation at 150 RPM, which is the speed of rotation with centrifugal force being greater than 1G. When the drum  224  rotates while maintaining the speed of rotation at 150 RPM during the second rough balancing, the controller  290  may again perform the above-described direct balancing by controlling the motions of the plurality of front balancing units  210  and the plurality of rear balancing units  220 . 
     During the second rough balancing, the controller  290  moves the plurality of front balancing units  210 , so that the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , may not exceed a predetermined front vibration amount of the second rough balancing, and moves the plurality of rear balancing units  220 , so that the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , may not exceed a predetermined rear vibration amount of the second rough balancing. In one implementation, the rear vibration amount of the second rough balancing may be greater than the front vibration amount of the second rough balancing. For example, as previously described, the laundry may tend to be collected in a rear section of the drum  224 . Further, the front vibration threshold amount of the second rough balancing in S 206  may be greater than the front vibration threshold amount of the first rough balancing in S 205 , and the rear vibration threshold amount of the second rough balancing in S 206  may be is greater than the rear vibration threshold amount of the first rough balancing in S 205  since the rotational speed of the drum  224  is relatively greater in S 206 . 
     During the second rough balancing, the controller  290  performs a substantially same direct balancing as the direct balancing performed during the first rough balancing. For example, the controller  290  may control repeated motions of the plurality of front balancing units  210  in the same rotational direction and in different rotational directions until the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , becomes equal to or smaller than the predetermined front vibration amount of the second rough balancing. Further, the controller  290  may control repeated motions of the plurality of rear balancing units  220  in the same rotational direction and in different rotational directions until the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , becomes equal to or smaller than the predetermined rear vibration amount of the second rough balancing. In addition, the controller  290  repeats direct balancing for the plurality of rear balancing units  220  and direct balancing for the plurality of front balancing units  210 . 
     When the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed the predetermined rear vibration amount of the second rough balancing, and the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , does not exceed the predetermined front vibration amount of the second rough balancing, the controller  290  controls the drum motor  213  to perform a next process in the rinsing and drying progression shown in  FIG. 13 . 
     As shown in  FIG. 13 , the controller  290  next controls the drum motor  213  to accelerate the drum  224  to 350 RPM, and controls the front vibration sensor  229   a  and the rear vibration sensor  229   b  to measure the front vibration amount and the rear vibration amount of the tub  222 . When the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , exceeds a predetermined front excessive vibration amount, or when the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , exceeds a predetermined rear excessive vibration amount, the controller  290  performs excessive balancing in S 209  by controlling the drum motor  213  to rotate the drum  224  while maintaining the speed of rotation. 
     While the drum  224  is accelerated from 150 RPM to 350 RPM, a large vibration may be produced in the main washer  200  due to resonance with a floor surface. Such resonance temporarily occurs when a natural frequency of the floor surface coincides with or is multiple of a vibration frequency of the main washer  200 . Accordingly, if vibration is not severe, the controller  290  accelerates the drum  224  to 350 RPM; and only when severe vibration is produced, the controller  290  performs excessive balancing. 
     Thus, if the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , does not exceed the predetermined front excessive vibration amount, or if the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed the predetermined rear excessive vibration amount, the controller  290  accelerates the drum  224  to 350 RPM; and if not, the controller  290  performs excessive balancing. In S 209 , the front excessive vibration amount may be greater than the rear excessive vibration amount. Further, the front excessive vibration amount may be greater than the front vibration amount of the second rough balancing, and the rear excessive vibration amount may be greater than the rear vibration amount of the second rough balancing. 
     While the drum  224  is accelerated, if the front vibration amount of the tub  222  exceeds the front excessive vibration amount, or if the rear vibration amount of the tub  222  exceeds the rear excessive vibration amount, the controller  290  performs an excessive balancing in S 207 , in which the controller  290  controls the drum motor  213  to maintain the speed of rotation of the drum  224 , and performs the above-described direct balancing for the plurality of front balancing units  210  and the plurality of rear balancing units  220 . For example, during the excessive balancing, the controller  290  may control a motion of the plurality of front balancing units  210  so that the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , does not exceed a predetermined front vibration amount of the excessive balancing; and may control a motion of the plurality of rear balancing units  220  so that the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed a predetermined rear vibration amount of the excessive balancing. In this example, the rear vibration amount of the excessive balancing may be greater than the front vibration amount of the excessive balancing. Further, the front vibration amount of the excessive balancing may be smaller than the front excessive vibration amount, but is equal to or greater than the front vibration amount of the second rough balancing; and the rear vibration amount of the excessive balancing may be smaller than the rear excessive vibration amount, but is equal to or greater than the rear vibration amount of the second rough balancing. 
     During the excessive balancing in S 207 , the controller  290  performs a similar direct balancing as the direct balancing performed during the first and the second rough balancing in S 205  and S 206 . For example, the controller  290  may cause the plurality of front balancing units  210  to repeatedly move in the same rotational direction and in different rotational directions until the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , becomes equal to or smaller than the predetermined front vibration amount of the excessive balancing. Further, the controller  290  may cause the plurality of rear balancing units  220  to alternate between moving in the same rotational direction and in different rotational directions until the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , becomes equal to or smaller than the predetermined rear vibration amount of the excessive balancing. In addition, the controller  290  may repeat direct balancing for the plurality of rear balancing units  220  and direct balancing for the plurality of front balancing units  210 . When the speed of rotation of the drum  224  reaches 350 RPM, the controller  290  may performs a next process in the rinsing and drying progression shown in  FIG. 13 . 
     For example, the controller  290  may perform third rough balancing in S 208  by controlling the drum motor  213  to rotate the drum  224  at 350 RPM, and controlling the plurality of front balancing units  210  and the plurality of rear balancing units  220 . During the third rough balancing, it is desired that the controller  290  operates the pump  236  to drain the wash water contained in the tub  222  to the outside through the drain passage  238 . When the drum  224  rotates while maintaining the speed of rotation at 350 RPM during the third rough balancing, the controller  290  performs the above-described direct balancing by controlling the plurality of front balancing units  210  and the plurality of rear balancing units  220 . 
     During the third rough balancing, the controller  290  controls motions of the plurality of front balancing units  210  so that the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , does not exceed a predetermined front vibration amount of the third rough balancing; and controls motions of the plurality of rear balancing units  220 , so that the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed a predetermined rear vibration amount of the third rough balancing. If the speed of rotation of the drum  224  exceeds 350 RPM, large vibration may be suddenly produced even by a small imbalance. Accordingly, the front vibration amount of the third rough balancing is smaller than the above-described front vibration amount of the first rough balancing, and the rear vibration amount of the third rough balancing is smaller than the above-described rear vibration amount of the first rough balancing. Further, the rear vibration amount of the third rough balancing is equal to or greater than the front vibration amount of the third rough balancing. 
     During the third rough balancing, the controller  290  may perform a similar direct balancing as the direct balancing performed during the first and the second rough balancing. For example, the controller  290  may control the plurality of front balancing units  210  to alternate between moving in the same rotational direction and in different rotational directions until the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , becomes equal to or smaller than the predetermined front vibration amount of the third rough balancing. Further, the controller  290  may control the plurality of rear balancing units  220  to alternate between moving in the same rotational direction and in different rotational directions until the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , becomes equal to or smaller than the predetermined rear vibration amount of the third rough balancing. In addition, the controller  290  may repeat direct balancing for the plurality of rear balancing units  220  and direct balancing for the plurality of front balancing units  210 . 
     When the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed the predetermined rear vibration amount of the third rough balancing, and the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , does not exceed the predetermined front vibration amount of the third rough balancing, the controller  290  accelerates the drum  224  to perform a next process next process in the rinsing and drying progression shown in  FIG. 13 . 
     The controller  290  may perform a first fine balancing in S 209  by controlling the drum motor  213  to rotate the drum  224  at 460 RPM, and controlling the plurality of front balancing units  210  and the plurality of rear balancing units  220 . During the first fine balancing, it is desired that the controller  290  operates the pump  236  to drain the wash water contained in the tub  222  to the outside through the drain passage  238 . When the drum  224  rotates while maintaining the speed of rotation at 460 RPM during the first fine balancing, the controller  290  may control the plurality of front balancing units  210  and the plurality of rear balancing units  220  to perform the above-described direct balancing and correction balancing. 
     When the drum  224  rotates at the speed of rotation of 600 RPM or higher, wash water contained in laundry is significantly reduced, such that the center of gravity of the drum  224  is changed, thereby causing a potential imbalance. However, when the speed of rotation of the drum  224  exceeds 460 RPM, balancing may not be performed since the plurality of front balancing units  210  and the plurality of rear balancing units  220  may not move actively by the motor  204 . Accordingly, when the drum  224  rotates at 600 RPM or higher (a period of “dehydration” to be described later), correction balancing may be performed at 460 RPM, during which balancing may be performed by anticipating the change of imbalance caused by reduction in the water content of the laundry. 
     During the direct balancing in the first fine balancing, the controller  290  may control the movement of the plurality of front balancing units  210 , so that the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , does not exceed a predetermined front vibration amount of the fine balancing, and may control the movement of the plurality of rear balancing units  220  so that the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed a predetermined rear vibration amount of the fine balancing. If the speed of rotation of the drum  224  exceeds 350 RPM, large vibration may be suddenly produced even by a small imbalance. Accordingly, the front vibration amount of the fine balancing is smaller than the above-described front vibration amount of the third rough balancing, and the rear vibration amount of the fine balancing is smaller than the above-described rear vibration amount of the third rough balancing. Further, the rear vibration amount of the fine balancing is equal to or greater than the front vibration amount of the fine balancing. 
     During the direct balancing in the first fine balancing process, the controller  290  may perform a substantially similar direct balancing as the direct balancing performed during the above-described rough balancing. For example, the controller  290  may control the plurality of front balancing units  210  to alternative between moving in the same rotational direction and moving in different rotational directions until the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , becomes equal to or smaller than the predetermined front vibration amount of the fine balancing. Further, the controller  290  controls the plurality of rear balancing units  220  to repeatedly alternatively between moving in the same rotational direction and moving in different rotational directions until the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , becomes equal to or smaller than the predetermined rear vibration amount of the fine balancing. In addition, the controller  290  repeats direct balancing for the plurality of rear balancing units  220  and direct balancing for the plurality of front balancing units  210 . 
     When the rear vibration amount of the tub  222 , which is measured by the rear vibration sensor  229   b , does not exceed the predetermined rear vibration amount of the fine balancing, and when the front vibration amount of the tub  222 , which is measured by the front vibration sensor  229   a , does not exceed the predetermined front vibration amount of the fine balancing, the controller  290  performs correction balancing. 
     The correction balancing may be performed by moving the plurality of front balancing units  210  and the plurality of rear balancing units  220  by anticipating the change of imbalance caused by reduction in the water content of the laundry when the drum  224  rotates at 600 RPM or higher. During the correction balancing, the controller  290  moves the plurality of front balancing units  210  and the plurality of rear balancing units  220  by applying a change of water content predetermined according to the types of laundry. The controller  290  may determine the types of laundry according to wash cycles set by a user for the types of laundry. Further, the controller  290  may determine the types of laundry based on an amount of laundry, which is the weight of laundry measured at the initial stage of washing, and based on the front vibration amount and the rear vibration amount of the tub  222 , which are measured during the first to third balancing. 
     The controller  290  calculates, through experiment, the change of imbalance caused by the change of water content according to the types of laundry. Based on the calculated change of imbalance, the controller  290  calculates a front first variation value, which is a variation value of the included angle between the plurality of front balancing units  210 , and a rear first variation value, which is a variation value of the included angle of the plurality of rear balancing units  220 , and the controller  290  stores the calculated values. The controller  290  controls the plurality of front balancing units  210  to move in different rotational directions, to change the included angle between the first front balancing unit  210   a  and the second front balancing unit  210   b  by a predetermined front first variation value. Further, the controller  290  controls the plurality of rear balancing units  220  to move in different rotational directions, to change the included angle between the first rear balancing unit  220   a  and the second rear balancing unit  220   b  by a predetermined rear first variation value. 
     Generally, as the water content of laundry is reduced when the drum  224  rotates at 600 RPM or higher, the front first variation value and the rear first variation value are set so that the included angles may increase. Accordingly, during the correction balancing in the first fine balancing process, the controller  290  may increase the included angle of the plurality of front balancing units  210  by the front first variation value, and may increase the included angle of the plurality of rear balancing units  220  by the rear first variation value. 
     Upon completing the correction balancing in the first fine balancing process, the controller  290  controls the drum motor  204  to perform a next process in the rinsing and drying procedure shown in  FIG. 13 . Depending on the types of laundry and washing cycles, the correction balancing described above in the first fine balancing process may be omitted. 
     The controller  290  performs first dehydration in S 210  by controlling the drum motor  213  to accelerate the drum to 950 RPM to remove moisture contained in laundry, and by controlling the front vibration sensor  229   a  and the rear vibration sensor  229   b  to measure the front vibration amount and the rear vibration amount of the tub  222 . During the first dehydration, the controller  290  intermittently operates the pump  236  to drain the wash water contained in the tub  222  to the outside through the drain passage  238 . The front vibration amount and the rear vibration amount of the tub  222 , which are measured during the first dehydration, are used for correction balancing in a second fine balancing process which will be described later. 
     After the speed of rotation of the drum  224  reaches 950 RPM (or other relatively high rotational speed for drying the laundry) and is maintained for a few seconds, the controller  290  performs a next process. The controller  290  controls the drum motor  213  to halt the drum  224 , and senses the amount of laundry, which is the weight of the laundry, in S 211 . Upon controlling the drum motor  213  to halt the drum motor  213 , the controller  290  senses the amount of the laundry by measuring time taken for the drum  224  to decelerate to a predetermined rotation speed (500 RPM in the embodiment shown in  FIG. 13 ). When the deceleration time gets longer, the controller may determine that the weight of the laundry relatively heavy, indicating a high level of the laundry amount. The controller  290  stores the relationship between the deceleration time and the laundry amount, which is obtained through experiment, and calculates the amount of the laundry based on the relationship. Based on the sensed amount of the laundry, the controller  290  performs correction balancing in a second fine balancing process and second dehydration, which will be described below. 
     Upon sensing the amount of the laundry, the controller  290  controls the drum motor  213  to rotate the drum  224  at 460 RPM and performs a next process. The controller  290  performs second fine balancing in S 212  by controlling the drum motor  213  to rotate the drum  224  at 460 RPM, and controlling the plurality of front balancing units  210  and the plurality of rear balancing units  220 . When the drum  224  rotates while maintaining the speed of rotation at 460 RPM during the second fine balancing, the controller  290  performs the above-described direct balancing and correction balancing by controlling the plurality of front balancing units  210  and the plurality of rear balancing units  220 . The direct balancing in the second fine balancing process is similar to the direct balancing in the first fine balancing process, such that detailed description thereof will be omitted. 
     The purpose of correction balancing in the second fine balancing process is the same as the purpose of correction balancing in the first fine balancing process. However, during the correction balancing in the second fine balancing process, a front second variation value, which is a variation value of the included angle between the plurality of front balancing units  210 , and a rear second variation value, which is a variation value of the included angle between the plurality of rear balancing units  220 , are determined based on the front vibration amount and the rear vibration amount of the tub  222  which are measured during the first dehydration, and based on the amount of laundry which is measured while the amount of laundry is sensed at a high speed. During the second dehydration process which will be described later, the drum  224  rotates at a very high speed, such that large vibration may be produced even by a small imbalance, requiring further precise correction balancing. 
     Based on the change of water content according to the types of laundry, as well as the front vibration amount and the rear vibration amount of the tub  222  which are measured during the first dehydration, and the amount of laundry which is measured while the amount of laundry is sensed at a high speed, the controller  290  calculates the front second variation value and the rear second variation value, and stores the calculated values. The controller  290  controls the plurality of front balancing units  210  to move in different directions, to change the included angle between the first front balancing unit  210   a  and the second front balancing unit  210   b  by a predetermined front second variation value. Further, the controller  290  controls the plurality of rear balancing units  220  to move in different directions, to change the included angle between the first rear balancing unit  220   a  and the second rear balancing unit  220   b  by a predetermined rear second variation value. 
     The front second variation value and the rear second variation value are set so that the included angles may increase or decrease, since the front second variation value and the rear second variation value are determined in consideration of the water content of laundry, as well as the front vibration amount and the rear vibration amount of the tub  222 , which are measured during the first dehydration, and the amount of laundry which is measured while the amount of laundry is sensed at a high speed. 
     Accordingly, during the correction balancing in the first fine balancing process, the controller  290  increases or decreases the included angle between the plurality of front balancing units  210  by the front first variation value, and increases or decreases the included value between the plurality of rear balancing units  220  by the rear first variation value. 
     Upon completing the correction balancing in the second fine balancing process, the controller  290  controls the drum motor  204  to perform a next process. Depending on the types of laundry, wash cycles, the amount of laundry which is measured while the amount of laundry is sensed at a high speed, and the front vibration amount and the rear vibration amount of the tub  222  which are measured during the first dehydration, the above-described correction balancing in the second fine balancing process may be omitted. 
     The controller  290  performs second dehydration in S 213  by controlling the drum motor  213  to accelerate the drum  224  to a maximum rotation speed to remove moisture contained in laundry. When the speed of rotation exceeds 1000 RPM, resonance occurs between the main washer  200  and the floor surface, such that the controller  290  sets the maximum rotation speed according to the amount of laundry which is measured while the amount of laundry is sensed at a high speed. In the embodiment, when the amount of laundry, which is measured while the amount of laundry is sensed at a high speed, is lower than a predetermined reference laundry amount sensed at a high speed, the controller  290  sets the maximum rotation speed to be 1060 RPM; and When the amount of laundry, which is measured while the amount of laundry is sensed at a high speed, is greater than the predetermined reference laundry amount sensed at a high speed, the controller  290  sets the maximum rotation speed to be 1010 RPM. During the second dehydration, the controller  290  intermittently operates the pump  236  to drain the wash water contained in the tub  222  to the outside through the drain passage  238 . After rotating the drum  224  at the maximum rotation speed for a predetermined period of time, the controller  290  controls the drum motor  213  to halt the drum  224 , and terminates dehydration. 
     The dryer  300  will be described as follows.  FIG. 15  is a perspective view of the dryer  300 , and  FIG. 16  is an exploded perspective view of the dryer  300 . Referring to  FIGS. 15 and 16 , a casing  310  forms an external appearance of the dryer  300 , and provides a space where a drum  304  and other elements are provided. The casing  310  includes a front panel  311 , a right plate  312 , a left plate  313 , a base  314 , a top plate  316 , and a back panel  315 . 
     The base  314  is formed to be approximately flat panel, and has the front panel  311 , the right plate  312 , the left plate  313 , and the back panel  315  provided thereon. The front panel  311 , the right plate  312 , the left plate  313 , the top plate  316 , and the back panel  315  form the front surface, the right surface, the left surface, the top surface, and the back surface of the casing  310  respectively. 
     The front panel  311  may have an introduction port  311   h , and a door  320  may be provided to open and close the introduction port  311   h . The door  320  has a door frame  321  which is rotatably connected to the front panel  311 ; and a door glass  322  which is installed at the door frame  321 . The door frame  321  has an opening formed approximately at the center of the front panel  311 , and the door glass  322  is installed at the opening. The door glass  322  is made of a transparent material so that a user may see into the drum  304  when the door  320  is closed, and may have a convex shape protruding inwards of the drum  304 . 
     A control panel  317  may be provided on the top of the front panel  311 . The control panel  317  may be provided with a display (e.g., LCD panel, LED panel, etc.) which shows an operation state of a clothes dryer, and an input part (e.g. button, dial, touch screen, etc.) which receives input of operation commands of the clothes dryer from a user. 
     The drum  304  may be rotatably provided inside the casing  310 . Further, a main motor  324  may be provided inside the casing  310  to rotate the drum  304 . The drum  304  has a substantially cylindrical shape having a front surface and a rear surface which are open, and the front surface communicates with the introduction port  311   h.    
     A lifter (or protrusion)  306  to lift up clothes may be provided at the inner circumference of the drum  304 . The lifter  306  protrudes from the inner circumference of the drum  304 , and may be elongated horizontally. A plurality of the lifters  306  may be provided along the inner circumference of the drum  304 . While the drum  304  rotates, the lifter  306  repeatedly lifts and drops the clothes. 
     A front supporter (or front drum frame)  305  and a rear supporter (or rear drum frame)  308 , which rotatably support the drum  304 , are provided inside the casing  310 . The front supporter  305  and the rear supporter  308  support the front end and the rear end of the drum  304  respectively. The front supporter  305  and the rear supporter  308  may have a guide which is formed to be a ring-shaped protrusion or a groove. As the front end or the rear end of the drum  304  is engaged with the guide, the drum  304  may stably rotate. Each of the front supporter  305  and the rear supporter  308  may be provided with a roller  319  which supports the drum  304 . An outer circumference of the drum  304  may come into contact with the roller  319 . 
     A bracket  329  is fixed on the base  314 , and the main motor  324  may be supported by the bracket  329 . The main motor  324  provides power to rotate the drum  304 , and at the same time rotates a blower fan  326  which will be described later. The main motor  324  may be a biaxial motor, and has a first driving axis  324   a  connected to the blower fan  326  and a second driving axis  324   b  having a driving pulley with which a belt wound around the drum  304  is engaged. 
     An idle pulley  328  may be installed at the bracket  329  to adjust tension of the belt. While the belt is engaged with the driving pulley and the idle pulley  328 , the belt surrounds the outer circumference of the drum  304 . While the main motor  324  operates, the belt is transferred by the driving pulley, and the drum rotates  304  by a frictional force applied between the belt and the driving pulley. 
     The blower fan  326  may rotate by the main motor  324 . By the rotation of the blower fan  326 , air inside the drum  304  is introduced into an air intake duct  331 . More specifically, a passage (not shown) is provided at a lower side of an opening  305   h  of the front supporter  305  to discharge air to the outside, and the air intake duct  331  guides the air, discharged through the passage, to the blower fan  326 . 
     When the blower fan  326  rotates, the air discharged from the drum  304  is guided by the air intake duct  331  to be supplied to the blower fan  326 . The air intake duct  331  is connected to a front surface of the front supporter  305 , and communicates with an intake port of the blower fan  326 . 
     The blower fan  326  includes a centrifugal fan  326   a  which is connected to the first driving axis  324   a  of the main motor  324 , and a fan housing  326   b  which accommodates the centrifugal fan  326   a . The fan housing  326   b  may be provided with: an inlet through which the air guided through the air intake duct  331  is introduced; and an outlet through which the air propelled by the centrifugal fan  326   a  is discharged. The outlet is connected with an air discharge duct  343  which comes into contact with the outside air, and the air discharged through the outlet is discharged to the outside through the casing  310 . 
     The front supporter  305  may be provided with a filter assembly  318 . The filter assembly  318  collects lint floating in the air discharged from the drum  304 . The filter assembly  318  includes: filter cases  318   a  and  318   b  which are fixed at the front supporter  305 ; and a lint filter  318   c  which is detachable from the filter cases  318   a  and  318   b . The filter cases  318   a  and  318   b  forms a space to accommodate the lint filter  318   c  (hereinafter referred to as an “accommodation space”), and a filter insertion hole is provided on the top surface of the filter cases  318   a  and  318   b , so that the lint filter  318   c  may be inserted into the accommodation space through the lifter insertion hole. The lint filter  318   c  may be inserted into or drawn out of the accommodation space through the filter insertion hole. 
     The filter cases  318   a  and  318   b  may include a front case  318   a  and a rear case  318   b . The front case  318   a  may be connected to a rear surface of the front supporter  305 . The rear case  318   b  is connected to the rear surface of the front case  318   a , such that an accommodation space may be formed between the rear case  318   b  and the front case  318   a . The rear case  318   b  may be provided with a grille  318   e , so as to introduce air in the drum  304  into the accommodation space. 
     The lint filter  318   c  may include a filter screen  318   d  of a mesh structure having minute holes. After the air introduced through the grille  318   e  is filtered by the filter screen  318   d , the air is guided to the air intake duct  331  through a passage formed at the front supporter  305 . 
     The rear case  318   b  may be provided with an electrode sensor  358  (see  FIG. 18 ). The electrode sensor  358  may include an anode and a cathode which are separated from each other. The anode and the cathode are exposed in the drum  304 . When the drum  304  rotates, a garment contacts the anode and the cathode, such that moisture contained in the garment causes both electrodes to be conductive, thereby forming a closed circuit. In this case, resistance value varies depending on the amount of moisture contained in the garment, such that values of current flowing in the circuit vary, and the controller (not shown) may obtain a degree of dryness based on the current values. The controller, in addition to obtaining the degree of dryness, may also control various electronic elements included in the clothes dryer. The controller may include a central processing unit (CPU) and a memory that stores data in a CPU readable manner. 
     The casing  310  may include a heater  342  to heat air. The rear supporter  308  is provided with an air supply hole  308   h , and the inner portion of the drum  304  communicates with the air supply duct  327  through the air supply hole  308   h . The air supply duct  327  guides air inside the casing  310  to the drum  304 . When negative pressure is applied in the drum  304  by the suction force of the blower fan  326 , hot air heated by the heater  342  is introduced to an inlet  327   a  of the air supply duct  327 , and is supplied into the drum  304  through an outlet  327   b  of the air supply duct  327 . 
     Referring to  FIGS. 17 to 21 , the dryer  300  may optionally include a basket  350   a  to accommodate garments independently from the drum  304 . The basket  350   a  may be detachable from the casing  310 . When some of the garments to be dried are needed to separately dried, the basket  350   a  is installed to put the garments therein. 
     A space (i.e., space where the garments are accommodated), which is formed by the basket  350   a , is at least partially provided inside the drum  304 , and the basket  350   a  is provided with a plurality of through-holes  352   h , through which hot air supplied into the drum  304  is introduced into the space. The basket  350   a  may be detachably connected with the front panel  311 . The basket  350   a  is inserted into the introduction port  311   h  formed at the front panel  311 . In this case, the basket  350   a  has an opening, which is formed at a front portion thereof and through which clothes are introduced, into the basket  350   a  and the space where clothes are accommodated is located inside the drum  304 . The opening of the basket  350   a  is opened and closed by the door  320 . While the door  320  is closed, the door glass  322  is extend into the inside of the basket  350   a.    
     The basket  350   a  may include a flange  351  having an opening through which clothes are introduced, and an accommodation chamber  352  which is recessed from the flange  351  to form a space to accommodate clothes. The plurality of through-holes  352   h  may be formed at the accommodation chamber  352 . While the basket  350   a  is completely mounted, the flange  351  comes into contact with the front panel  311 , and the accommodation chamber  352  is placed inside the drum  304 . 
     A basket cover  360  may be further provided, which divides the space in the accommodation chamber  352  into a front region and a rear region. The basket cover  360  is an independent member separate from the basket  350   a , and may be inserted into or drawn out of the basket  350   a . After clothes are put into the accommodation chamber  352 , the basket cover  360  is inserted, and the door  320  is closed, clothes are placed at the rear side of the basket cover  360  (i.e., rear region), and the door glass  322  is inserted into the front side thereof (i.e., front region). In this manner, even when the door  320  is opened, the basket cover  360  may prevent clothes from falling out of the accommodation chamber  352 . 
     The basket cover  360  is desirably made of a material, such as a synthetic resin or rubber, which may be transformed to some degree. However, the basket cover  360  is not limited thereto, and depending on embodiments, the basket cover  360  may be rotatably connected so as to open and close the accommodation chamber  352 . 
     The basket  350   a  may further include a rib  353 , which protrudes from an outer surface of the accommodation chamber  352  in a radial direction. The rib  353  is elongated horizontally, and the front end of the rib  353  is connected with the flange  351 . A removable groove  531  (see  FIG. 20 ), into which the circumference of the introduction port  311   h  is inserted, may be formed at the rear side of the flange  351  of the basket  350   a . While the circumference of the introduction port  311   h  is inserted into the removable groove  353   a , the flange  351  may be adhered to the front panel  311 . 
     The removable groove  353   a  may be formed at the rib  353 . The rib  353  may further protrude outwards in a radial direction from the circumference of the introduction port  311   h , and the opening of the removable groove  353   a  may be positioned at the protruding portion. 
     As described above, in a structure where the rib  353  further protrudes outwards in a radial direction from the circumference of the introduction port  311   h , the circumference of the introduction port  311   h  may interfere with the rib  353  when the basket  350   a  is mounted. However, the rib  353  may be made of a synthetic material, and the entire basket  350   a , including the rib  353 , may be integrally formed of a synthetic resin, such that when the rib  353  interferes with the circumference of the introduction port  311   h , the basket  350   a  may be transformed to some degree, thereby allowing the circumference of the introduction port  311   h  to be inserted into the removable groove  353   a.    
     The rib  353  may have a slope  353   b , which is tilted such that as the rib  353  nears to the rear side of the removable groove  353   a  from the opening thereof, the rib  353  may be closer to the accommodation chamber  352 . In the embodiment, the slope  353   b  is formed until a portion where the slope  353   b  and the accommodation chamber  352  meet. However, the slope  353   b  is not limited thereto, and may be formed only in a section that extends from the opening of the removable groove  353   a.    
     When the basket  350   a  is removed from the introduction port  311   h , a portion from the opening of the removable groove  353   a  to the beginning of the slope  353   b  may be formed to be a curved surface protruding outwards from the rib  353 , so that the circumference of the introduction port  311   h  may be smoothly released from the removable groove  353   a.    
     When the basket  350   a  is inserted into the introduction port  311   h , the circumference of the introduction port  311   h  comes into contact with the slope  353   b ; and when the basket  350   a  is continuously pushed, the removable groove  353   a  reaches a position corresponding to the circumference of the introduction port  311   h , thereby allowing the circumference of the introduction port  311   h  to be inserted into the removable groove  353   a.    
     The front panel  311  may be made of a metal plate. When the front panel  311  is formed, an opening corresponding to the introduction port  311  is formed at the metal plate, and the circumference of the opening is curled inwards of the casing  310 , thereby forming a hem  112  along the circumference of the introduction port  311   h . The introduction port  311   h  and an access opening of the drum  304  communicate with each other through the opening  305   h  of the front supporter  305 . When viewed from the front side, the introduction port  311   h  is provided inside the opening  305   h , and the hem  311   a  is provided inside the opening  305   h.    
     A plurality of ribs  353  may be formed along the circumference of the accommodation chamber  352 . In the embodiment, the rib  353  is provided at the top side, the left side, and the right side of the accommodation chamber  352 , and the hem  121  is inserted into the removable groove  353   a  formed at each rib  353 , thereby preventing movement of the basket  350   a  to the top side, the left side, and the right side. However, the position and the number of the ribs  353  are not limited thereto. 
     The basket  350   a  extends from the accommodation chamber  352 , and may further include an anchor  354 , which hooks onto the grille  318   e . The grille  318   e  has an opening which opens rearward, and the anchor  354  may include a hook  354   a  which is inserted into the opening at the rear side of the grille  318   e . Two or more baskets  350   a  may be provided. While the basket  350   a  is completely mounted, the anchor  354  hooks onto the grille  318   e , thereby preventing rotation of the basket  350   a  inside the introduction port  311   h . It is desired that there are two or more anchors  354 , and a pair of anchors  354  may be provided symmetrically on the left side and the right side when the basket  350   a  is viewed from the front. 
     The basket  350   a  may be mounted by being diagonally inserted into the introduction port  311   h , and the anchor  354  hooks onto the grille  318   e . Then, the basket  350   a  is horizontally arranged, and is pushed into the introduction port  311   h  more deeply. In this case, the hem  311   a  forming the circumference of the introduction port  311   h  interferes with or otherwise contacts the slope  353   b  of the rib  353 , but when the basket  350   a  is further deeply pushed, the interference may be overcome, and the hem  311   a  may be inserted into the removable groove  353   a , thereby completing mounting of the basket  350   a.    
     The ironing part (or ironing station)  400  may be described as follows.  FIG. 22  is a perspective view illustrating an operation state of the ironing part  400 ,  FIG. 23  is a side cross-sectional view of a dehumidifying and ironing module  410 , and  FIG. 24  is a diagram illustrating an example of an dehumidifying unit  412  included in the dehumidifying and ironing module  410 .  FIG. 25  is a diagram illustrating a state where a first storage space  414  is opened in the dehumidifying and ironing module  410 , and  FIG. 26  is a diagram illustrating a state where a second storage space  415  is opened in the dehumidifying and ironing module  420 .  FIG. 27  is a control block diagram for the ironing part  400 . 
     Referring to  FIGS. 22 to 27 , the ironing part  400  includes a dehumidifying and ironing module  410  and a drying module  420 . The dehumidifying and ironing module  410  may be installed on an indoor floor surface, and the drying module  420  may be installed on the indoor wall or the ceiling. The dehumidifying and ironing module  410  may suction and dehumidify indoor air, and may discharge the dehumidified air. Further, the dehumidifying and ironing module  410  may provide a horizontal surface to iron laundry. 
     The drying module  420  includes a hanging part (or hanging bar)  422 , on which a hanger  421  is hung, and may suction indoor air to send the suctioned air to laundry hung on the hanger  421 . The laundry on the hanger  421  may be dried by air sent by the drying module  420 . In another example, the laundry may be hung on the hanging part  422 . 
     The dehumidifying and ironing module  410  includes a cabinet  411 , a dehumidifying unit (or dehumidifier)  412  installed at the cabinet  411 , and a first blower unit (or first blower)  413  installed at the top of the cabinet  411 . The cabinet  411  may be formed in a hexahedral (or box-like) shape and has an open front surface and a cavity. The cabinet  411  may include a second upper panel  411   a  which is provided on the top of the cabinet  411 . The second upper panel  411   a  may form the top surface of the cabinet  411 , and is formed in a substantially flat rectangular shape. The top surface of the cabinet  411  is formed to be substantially flat with the second upper panel  411   a . A user may put an ironing board  1  on the flat top surface of the cabinet  411 , and position laundry on the ironing board  1  to iron the laundry. 
     A first storage space  414  and a second storage space  415  may be provided at the open front surface of the cabinet  411 . The first storage space  414  may be provided above the second storage space  415 ; and the second storage space  415  may be provided below the first storage space  414 . The first storage space  414  may be opened and closed by sliding forward and rearward in the cabinet  411 , and the second storage space  415  may also be opened and closed by sliding forward and rearward in the cabinet  411 . When opened, the first storage space  414  may protrude forward from the cabinet  411 , and when closed, the first storage space  415  may be inserted into the cavity of the cabinet  411 . When opened, the second storage space  415  may also protrude forward from the cabinet  411 , and when closed, the second storage space  415  may also be inserted into the cavity of the cabinet  411 . 
     The first storage space  414  may store the ironing board  1 . When a user wishes to iron laundry, the user may open the first storage space  414 , take out the ironing board  1 , and put the ironing board  1  on the top surface of the cabinet  411  to iron the laundry. 
     The second storage space  415  may include a first storage part (or first storage region)  415   a  and a second storage part (or second storage region)  415   b . The first storage part  415   a  and the second storage part  415   b  may be separated by a partition wall  415   c . The first storage part  415   a  may include a condensate water container  2 , and the second storage part  415   b  may include at least one of an iron  3 , a steamer  4 , or a remover (or fluff remover)  5 . 
     The condensate water container  2  may be a container or bin that stores condensate water generated when the dehumidifying unit  412  dehumidifies indoor air. 
     The iron  3  may be a device to iron laundry by converting electric power into heat. The iron  3  may have a stream spray function. A user may put the laundry on the ironing board  1 , to iron the laundry by using the iron  3 . 
     The steamer  4  is a device the spray high-temperature steam into the laundry. A user may use the steamer to spray high-temperature steam on the laundry hung on the drying module  420  to iron the laundry. 
     The remover  5  is a device for remove foreign materials, such as fluff, from the laundry. For example, the remover  5  may shave a clothing surface to remove fluff (or lint) extending from the surface. While hanging the laundry on the drying module  420 , a user may rub the remover  5  on the laundry to remove fluff from the laundry. 
     A wireless charging unit (or wireless charger)  411   c  may be installed on the top of the cabinet  411 . The wireless charging unit  411   c  may include a wireless inductive charging coil (not shown). The wireless charging unit  411   c  may be positioned such that a top surface of the wireless charging unit  411   c  is at a substantially similar height as a top surface of the upper panel  411   a  of the cabinet  411 . The wireless charging unit  411   c  may be inserted into the second upper panel  411   a . The devices in the second storage space  415   b , such as the iron  3 , the steamer  4 , and the remover  5 , may be placed on the top of the wireless charging unit  411   c  for wireless charging. The iron  3 , the steamer  4 , and the remover  5  each have a battery, and desirably a coil which receives an inductive current from the wireless charging coil of the wireless charging unit  411   c  to charge the battery. 
     A suction grille  411   b  may be provided at the cabinet  411 . The suction grille  411   b  may form one or more air inlets into a central cavity of the cabinet  411 . The suction grille  411   b  may be referred to as the air inlet. In the embodiment, the air inlet is formed on the front surface of the cabinet  411 , but is not limited thereto, and may be formed on at least one of the front surface, the lateral surface, and the rear surface of the cabinet  411 . Hereinafter, the air inlet is described as being formed on the front surface of the cabinet  411 . The suction grille  411   b  is provided below the second storage space  415 . Air may be suctioned into the cabinet  411  through the suction grille  411   b.    
     The dehumidifying unit  412  is provided inside the cabinet  411  to dehumidify air suctioned into the cabinet  411  through the suction grille  411   b . The dehumidifying unit  412  may include a cooling cycle circuit using a refrigerant. For example, the dehumidifying unit  412  may include a compressor  412   a , a condenser (or condenser coil)  412   b , an expander (or expansion valve)  412   c , and an evaporator  412   d . The compressor  412   a  may compress a refrigerant; the condenser  412   b  may condense the refrigerant compressed by the compressor  412   a ; the expander  412   c  may expand the refrigerant condensed by the condenser  412   b ; and the evaporator  412   d  may evaporate the refrigerant expanded by the expander  412   c . In other examples, the dehumidifying unit  412  may include a heater to warm and dry the air or a desiccant. 
     The evaporator  412   d  may cool and dehumidify the air suctioned into the cabinet  411  through the suction grille  411   b  by heat-exchanging. When the evaporator  412   d  cools the air inside the cabinet  411 , water vapor contained in the air of the cabinet  411  is cooled and changed into condensate water, and the condensate water may be formed on the evaporator  412   d . The condensate water container  2  is provided below the evaporator  412   d  to receive and store the condensate water dropping from the evaporator  412   d.    
     The compressor  412   a  and the condenser  412   b  may be connected to each other through a first refrigerant pipe  412   e . The condenser  412   b  and the expander  412   c  may be connected to each other through a second refrigerant pipe  412   f . The expander  412   c  and the evaporator  412   d  may be connected to each other through a third refrigerant pipe  412   g . The evaporator  412   d  and the compressor  412   a  may be connected to each other through a fourth refrigerant pipe  412   h . The refrigerant may circulate by sequentially passing the compressor  412   a , the first refrigerant pipe  412   e , the condenser  412   b , the second refrigerant pipe  412   f , the expander  412   c , the third refrigerant pipe  412   e , the evaporator  412   d , and the fourth refrigerant pipe  412   h.    
     The first blower unit  413  may discharge the air, dehumidified in the cabinet  411  by the dehumidifying unit  412 , to the outside of the cabinet  411 . When operating, the first blower unit  413  may be drawn out of the cabinet  411 , and when stopping the operation, the first blower unit  413  may be inserted into the cabinet  411 . When operating, the first blower unit  413  may be drawn out of the cabinet  411  to protrude upward from the cabinet  411 . When stopping the operation, the first blower unit  413  is inserted into the cabinet  411 , such that the top surface of the first blower unit  413  is horizontal to the top surface of the cabinet  411 . 
     An access hole  411   d , through which the first blower unit  413  may pass, is formed on the top of the cabinet  411 . The access hole  411   d  may be formed close to a rear end of the second upper panel  411   a , such that a sufficient area may be provided on the second upper panel  411   a  to place the ironing board  1  in front of the access hole  411   d.    
     The first blower unit  413  may include a case  413   a , and a fan  413   b  which suctions the air, dehumidified in the cabinet  411  by the dehumidifying unit  412 , into the case  413   a . A discharge grille  413   c  may be installed at the front surface of the case  413   a . The discharge grille  413   c  may form one or more air outlets. The discharge grille  413   c  may be referred to as the air outlet. The case  413   a  may have an open lower end, so that the dehumidified air, sent by the fan  413   b , may enter the case  413   a.    
     The fan  413   b  may be installed inside the cabinet  411 , and may rotate by a driving force of a motor (not shown). The fan  413   b  may be provided above the evaporator  412   d , and may be provided below the case  413   a . The fan  413   b  may be vertically interposed between the case  413   a  and the evaporator  412   d . The fan  413   b  may have a rotation axis which extends vertically. When rotating, the fan  413   b  may suction the air, which is dehumidified in the cabinet  411  by the evaporator  412   d , to send the suctioned dehumidified air into the case  413   a ; and the case  413   a  may discharge the dehumidified air sent by the fan  413   b  forward of the case  413   a  through the discharge grille  413   c.    
     When the fan  413   b  operates, the case  413   a  may protrude upward from the cabinet  411  through the access hole  411   d  formed on the second upper panel  411   a , so as to discharge the dehumidified air sent by the fan  413   b  to the outside of the case  413   a  through the discharge grille  413   c . Further, when the fan  413   b  stops operating, the case  413   a  may be re-inserted into the cabinet  411  through the access hole  411   d . When the case  413   a  is completely inserted into the cabinet  411  through the access hole  411   d , the top surface of the case  413   a  is provided horizontal to the top surface of the second upper panel  411   a . The case  413   a  may be installed to be movable upward and downward of the second upper panel  411   a , so that when the fan  413   b  operates, the case  413   a  may protrude upward from the cabinet  411 , and when the fan  413   b  stops operating, the case  413   a  may be reinserted into the case  411 . 
     The drying module  420  may include a second blower unit  424  and a hanging part  422  installed at the second blower unit  424 . The second blower unit  424  suctions indoor air to send the air to laundry hung on the hanging part  422  by using the hanger  421 . The laundry on the hanging part  422  may be dried by the air sent by the second blower unit  424 . As air surrounding the laundry remains to be dry by using the dehumidified air is discharged by the first blower unit  413 , and the laundry is dried by the air discharged by the second blower unit  424 , a drying time of the laundry may be reduced. 
     The second blower unit  424  may include a housing (not shown) having an air inlet (not shown) and an air outlet (not shown); and a fan (not shown) which is provided inside the housing to suction air, suctioned into the housing through the air inlet, and to send the air through the air outlet. A discharge grille  424  may be provided at a rear lower portion of the second blower unit  424 . The discharge grille  424  may form one or more air inlets. The discharge grille  424  may be tilted with a front end being provided higher than a rear end, so as to discharge air forward and downward toward the hung laundry. 
     The first blower unit  413  may be provided below and rearward of the hanging part  422 , such that the first blower unit  413  may discharge the dehumidified air forward and around the laundry. Further, the second blower unit  424  may discharge air forward and downward from the rear side of the hanging part  422  and toward the laundry. 
     The first blower unit  413  discharges the dehumidified air downward of the laundry, and the second blower unit  424  discharges air toward a portion where the dehumidified air, discharged by the first blower unit  413 , is present. Accordingly, the air, which is sent by the second blower unit  424  to the laundry hung on the hanger  421 , is mixed with vapor generated in the course of drying the laundry, and then meets the dehumidified air discharged by the first blower unit  413 , thereby reducing a drying time of the laundry. 
     The ironing part  400  may further include a humidity sensor  416  and a controller  417 . The humidity sensor  416  may sense humidity values of surrounding air. The humidity values sensed by the humidity sensor  416  may be input to the controller  417 . Upon receiving the humidity values sensed by the humidity sensor  416 , the controller  417  may compare the humidity values with a predetermined value or predetermined humidity level. 
     When the humidity value measured by the humidity sensor  416  is equal to or greater than the predetermined value, the controller  417  may operate the dehumidifying unit  412  and the first blower unit  413 . Furthermore, when the humidity value input detected by the humidity sensor  416  is lower than the predetermined value, the controller  417  may stop the dehumidifying unit  412  and the first blower unit  413 . Accordingly, when the dryer  400  dries the laundry, the dehumidifying unit  412  and the first blower unit  413  repeatedly operate and stop automatically according to the surrounding humidity of the laundry, thereby reducing power consumption. 
     The humidity sensor  416  may be installed close to the laundry hung on the drying module  420 , so that the dehumidifying unit  412  and the first blower unit  413  may operate automatically only when the humidity of the surrounding air of the laundry is equal to or greater than the predetermined value. Accordingly, the humidity sensor  416  may be installed at the second upper panel  411   a  on the top of the cabinet  411 . 
     The present disclosure provides a laundry treatment apparatus which may sequentially perform pre-washing, main washing, drying, and ironing in one place. In accordance with an aspect of the embodiments of the disclosure, there is provided a laundry treatment apparatus including: a pre-washer configured to perform pre-washing of laundry in an accommodation space which accommodates the laundry and has a sink bowl having an open top portion; a main washer which is provided beside the pre-washer, and performs main washing, rinsing, and spin-drying of the laundry when the laundry, pre-washed by the pre-washer, is introduced into the main washer from a front side; a dryer which is provided beside the main washer, and performs drying of the laundry when the laundry, spin-dried by the main washer, is introduced into the dryer from a front side; an ironing part which is provided beside the dryer, and has a flat top surface to iron the laundry dried by the dryer; a first upper panel which is provided on a top portion of the main washer and the dryer and has a flat top surface; a second upper panel which forms the top surface of the ironing part; and a lid which is provided on a top portion of the pre-washer to open and close the accommodation space, and a top surface of which is at the same height as the top surface of the first upper panel and a top surface of the second upper panel. Thus, pre-washing, main washing, drying, and ironing may be sequentially performed in one place, which may be provided to a user as an integrated process. 
     It will be understood that when an element or layer is referred to as being “on” another element or layer, the element or layer can be directly on another element or layer or intervening elements or layers. In contrast, when an element is referred to as being “directly on” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure. 
     Spatially relative terms, such as “lower”, “upper” and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “lower” relative to other elements or features would then be oriented “upper” relative the other elements or features. Thus, the exemplary term “lower” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the 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 features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Embodiments of the disclosure are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the disclosure. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the disclosure should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. 
     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 to which this disclosure belongs. 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 will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.