Patent Publication Number: US-2023152020-A1

Title: Ice maker and refrigerator

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The application is a continuation of U.S. application Ser. No. 16/685,696, filed on Nov. 15, 2019, which claims priority under 35 U.S.C. § 119 and 35 U.S.C. § 365 to Korean Patent Application Nos. 10-2018-0142079 filed on Nov. 16, 2018 and 10-2019-0081739 filed on Jul. 6, 2019, whose entire disclosures are hereby incorporated by reference. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure relates to an ice maker and a refrigerator. 
     Discussion of the Related Art 
     In general, a refrigerator is a home appliance for storing foods at a low temperature by low temperature air. 
     The refrigerator uses cold-air to cool inside of a storage space, so that the stored food may be stored in a refrigerated or frozen state. 
     Typically, an ice maker for making ice is provided inside the refrigerator. 
     The ice maker is configured to receive water from a water source or a water tank in a tray to make ice. 
     Further, the ice maker is configured to remove the ice from the ice tray in a heating or twisting manner after the ice-making is completed. 
     As such, the ice maker, which automatically receives the water and removes the ice, has an open top to scoop molded ice. 
     As described above, the ice made in the ice maker having a structure as described above may have at least one flat surface such as crescent or cubic shape. 
     When the ice has a spherical shape, it is more convenient to ice the ice, and also, it is possible to provide different feeling of use to a user. Also, even when the made ice is stored, a contact area between the ice cubes may be minimized to minimize a mat of the ice cubes. 
     Korean Patent Registration No. 10-1850918 as Prior Art document discloses an ice maker. 
     The ice maker of Prior Art document includes an upper tray in which a plurality of upper cells of a hemispherical shape are arranged and a pair of link guides extending upwardly from both sides are disposed, a lower tray in which a plurality of lower cells of a hemispherical shape are arranged and which is pivotally connected to the upper tray, a pivoting shaft connected to rear ends of the lower tray and the upper tray to allow the lower tray to pivot relative to the upper tray, a pair of links having one end thereof connected to the lower tray and the other end thereof connected to the link guide, and an ejecting pin assembly having both ends thereof respectively connected to the pair of links while being respectively inserted into the link guides, wherein the ejecting pin assembly ascends and descends together with the link. 
     In Prior Art document, it is possible to produce the spherical ice by the hemispherical upper cell and the hemispherical lower cell. However, since ice cubes are generated in the upper cell and the lower cell at the same time, bubbles contained in water are not completely discharged, and ice generated by the bubbles dispersed in the water is opaque. 
     Further, since the plurality of cells are arranged in line, a heat transfer amount of cold-air is maximized in cells located at both ends of the plurality of cells. In this case, since an ice generation speed of the cells located at the both ends of the plurality of cells is high, when water in the cells at the both ends is phase-changed into ice, the water flows to cells located between the both ends by an expansion force, so that a shape of the ice is deformed from the sphere shape. 
     Further, when the cold-air is provided in one direction, ice formation may be started from a cell at an end side where the cold-air is introduced. In this case, in a cell where the ice formation occurs at last, an amount of water becomes excessively greater than a predefined amount, resulting in generation of ice having a shape, which is very different from the spherical shape. 
     SUMMARY OF THE DISCLOSURE 
     A purpose of an embodiment of the present disclosure is to provide an ice maker and a refrigerator that allow cold-air to be guided to pass above a plurality of ice chambers, so that spherical ice is produced at a uniform speed regardless of a type and a location of the refrigerator. 
     Another purpose of an embodiment of the present disclosure is to provide an ice maker and a refrigerator that make ice-making speeds in a plurality of spherical ice chambers uniform even in a structure in which cold-air is supplied from one side. 
     Another purpose of an embodiment of the present disclosure is to provide an ice maker and a refrigerator in which a thermally-insulating structure is added to a spherical ice chamber where cold-air is concentrated, so that ice formation is performed at a uniform speed in all chambers. 
     Another purpose of an embodiment of the present disclosure is to provide an ice maker and a refrigerator in which ice formation is delayed in a spherical ice chamber close to an inlet of cold-air, and the ice formation is induced to be performed first in a chamber disposed between chambers, so that water is distributed to the chambers at both sides, thereby forming evenly shaped spherical ice. 
     Another purpose of an embodiment of the present disclosure is to provide an ice maker and a refrigerator that prevent an upper tray from being deformed during an ice-removal process, thereby preventing jam between the upper tray and other components. 
     Another purpose of an embodiment of the present disclosure is to provide an ice maker and a refrigerator that prevent cold-air from invading through a space between an upper tray and a shield and deteriorating an thermal-insulation performance. 
     An ice maker and a refrigerator according to the present embodiment may include an upper tray, a lower tray pivotably coupled with the upper tray to define a spherical ice chamber thereon, a cold-air hole for discharging cold-air to pass the upper tray, and a thermally-insulating portion formed on one side of the upper tray corresponding to an ice chamber closest to the cold-air hole to block cold-air from invading. 
     An ice maker and a refrigerator according to the present embodiment may include a cold-air hall, an upper tray on which a plurality of ice chambers in which a plurality of spherical ice cubes are formed are formed, a lower tray, a thermally-insulating portion formed on a portion exposed to a cold-air flowing space of an ice chamber close to the cold-air hole. 
     A shield that shields the thermally-insulating portion from above may be formed upward of the thermally-insulating portion. 
     An ice maker and a refrigerator according to the present embodiment may include a cold-air guide to guide cold-air, ice chambers arranged continuously from an exit of the cold-air guide, and a thermally-insulating portion formed at a position corresponding to an ice chamber closest to the cold-air exit among the ice chambers to delay ice-making speed by blocking the cold-air. 
     An ice maker and a refrigerator according to the present embodiment may include upper and lower trays defining a spherical ice chamber, a thermally-insulating portion formed on a portion of the upper tray to block cold-air, an upper ejector for passing through an ejector-receiving opening to remove the ice, a rib connecting ejector-receiving openings adjacent to each other, a shield for shielding the thermally-insulating portion from above, and a cut that is cut from the shield to receive the rib therein. 
     A refrigerator according to the present embodiment may include a cabinet having a refrigerating compartment and a freezing compartment defined therein, and an ice maker disposed in the freezing compartment, wherein the ice maker includes a cold-air hole for receiving cold air, an upper tray made of an elastic material, wherein the upper tray is positioned to be exposed to the cold-air flowing from the cold-air hole, a lower tray made of an elastic material, wherein the lower tray is coupled to the upper tray to define a plurality of spherical ice chambers therebetween, a driver for pivoting the lower tray to open the spherical ice chambers, at least one thermally-insulating portion formed at a top face of the upper tray and corresponding to at least one of the ice chambers respectively, wherein the at least one thermally-insulating portion is constructed to prevent the cold-air from invading the at least one corresponding ice chamber. 
     In one implementation, the thermally-insulating portion may be exposed to the cold-air flowing from the cold-air hole, and wherein a thickness of an ice chamber having the thermally-insulating portion formed thereon may be greater than thicknesses of ice chambers without the thermally-insulating portion. 
     In one implementation, the thermally-insulating portion may protrude upward from an outer face of the ice chamber exposed upwards. 
     In one implementation, the plurality of ice chambers may be arranged in a row, and wherein the thermally-insulating portion may be formed at a location corresponding to an ice chamber closest to the cold-air hole. 
     In one implementation, an opening for discharging the cold-air may be defined opposite the cold-air hole, and wherein the plurality of ice chambers may be arranged in line between the cold-air hole and the opening. 
     In one implementation, the thermally-insulating portion may be formed at a location corresponding to an ice chamber closest to the cold-air hole. 
     In one implementation, the refrigerator may further include a cold-air guide for guiding flow of the cold-air, wherein the plurality of ice chambers may be arranged continuously from an exit of the cold-air guide, and wherein the thermally-insulating portion may be formed at a position corresponding to an ice chamber closest to the exit of the cold-air guide. 
     In one implementation, a shield for shielding the thermally-insulating portion to further block the cold-air from invading may be formed upward of the thermally-insulating portion. 
     In one implementation, an air layer may be formed between the thermally-insulating portion and the shield. 
     An ice maker according to the present embodiment may include an upper tray made of an elastic material, wherein a plurality of upper chambers are defined in the upper tray, each ejector-receiving opening defined in a top face of the upper tray and corresponding to each of the plurality of upper chambers, an upper casing disposed on a top of the upper tray, wherein the upper casing has a tray opening defined therein to expose the top face of the upper tray including the ejector-receiving openings, a lower tray made of an elastic material, wherein the lower tray is coupled to the upper tray to define a plurality of spherical ice chambers therebetween, a lower support supporting the lower tray thereon, a driver connected to the lower support for pivoting the lower tray to open the spherical ice chambers, an upper ejector disposed above the upper tray, wherein the upper ejector is configured to pass through the ejector-receiving opening and remove each ice from each ice chamber, and at least one thermally-insulating portion formed at the top face of the upper tray exposed through the tray opening, wherein the thermally-insulating portion is formed to surround at least one ejector-receiving opening, wherein the at least one thermally-insulating portion is formed in at least one position corresponding to at least one of the ice chambers respectively. 
     In one implementation, a thickness of an ice chamber having the thermally-insulating portion may be increased by the thermally-insulating portion protruding outwardly from the tray opening. 
     In one implementation, a thickness of a top face of the upper tray corresponding to an ice chamber having the thermally-insulating portion may be greater than a thickness of a top face of the upper tray corresponding to an ice chamber without the thermally-insulating portion. 
     In one implementation, a cold-air guide for guiding flow of the cold-air may be formed on the upper casing, wherein the plurality of ice chambers may be arranged continuously from an exit of the cold-air guide. 
     In one implementation, the thermally-insulating portion may be formed above an ice chamber on one side closest to the cold-air guide exit. 
     The ice maker may include a cold-air hole opened at one side of the upper casing and through which the cold-air is introduced, and a through-opening opened at a side far away from the cold-air hole to discharge the cold-air, wherein the multiple ice chambers may be arranged along the cold-air hole and the through-opening, and wherein the thermally-insulating portion may be formed above the ice chamber closest to the cold-air hole. 
     In one implementation, wherein a shield extending from a circumference of the ejector-receiving opening to the ejector-receiving opening to shield the thermally-insulating portion may be further formed upward of the thermally-insulating portion. 
     In one implementation, each of the ejector-receiving openings may be defined in a top of each of the plurality of ice chambers, and wherein the ice maker may further include an opening-defining wall extending upward along the circumference of the ejector-receiving opening. 
     In one implementation, a connection rib for connecting the opening-defining wall with an opening-defining wall of a neighboring ejector-receiving opening may be formed on the opening-defining wall, and wherein a cut may be defined in the shield to allow the connection rib to pass therethrough. 
     In one implementation, a width of the cut may decrease upwardly, and wherein a width of a top of the cut may correspond to a width of the connection rib. 
     In one implementation, the ice maker may further include an additional connection rib formed on the upper casing at a position adjacent to both ends of the cut, wherein the additional connection rib is in contact with an outer face of the opening-defining wall, an outer face of the upper tray, and an inner face of the shield. 
     In one implementation, the ice maker may further include connection ribs arranged along a circumference of the opening-defining wall to connect an outer face of the opening-defining wall and an outer face of the upper tray with each other. 
     In one implementation, rib grooves for respectively receiving at least some of the connection ribs therein may be defined in the shield. 
     An air layer may be formed between the insulating layer and the shield. 
     The thermally-insulating portion may be integrally formed with the upper tray during molding of the upper tray. 
     The ice maker and the refrigerator according to the present disclosure have following effects. 
     According to the present embodiment, the cold-air flowing into the ice maker through the cold-air hole passes above the ice chamber by the cold-air guide, so that the ice formation speed may become uniform and the ice may maintain the spherical shape. 
     Further, according to the present embodiment, the ice formation speed is delayed by the lower heater for supplying the heat to the ice chamber, so that the bubbles may move from the portion where the ice is formed toward the water, thereby producing the transparent ice. 
     Further, according to the present embodiment, regardless of the type of the refrigerator in which the ice maker is mounted, the cold-air passed through the cold-air hole moves along the cold-air guide, so that the movement patterns of the cold-air become almost the same. Therefore, the transparency of the ice may be uniform regardless of the type of refrigerator. 
     Further, according to the present embodiment, the cold-air hole through which the cold-air is supplied is defined at one side, so that the cold-air may be concentrated while the cold-air flowed by the cold-air guide passes a specific chamber first. However, a thicker thermally-insulating portion is formed on a top face of the corresponding chamber, so that excessively rapid ice formation occurring in the specific chamber may be prevented, and the ice formation speed may be uniform in the entire chambers. 
     In particular, the additional components may be minimized and the ice-making speeds in the plurality of chambers may be made uniform through the thickness control of the upper tray. 
     Further, when the ice formation speeds in all of the chambers are uniform by the thermally-insulating portion, it may be prevented that, as ice is formed first in a specific chamber, supplied water flows and then an excessive amount of water is stored in a specific chamber to form non-spherical ice. 
     Further, according to the present embodiment, the cold-air is supplied from one side by the cold-air guide, and simultaneously, the ice formation is prevented from occurring first in the chamber close to the cold-air guide, so that the ice formation may be induced to occur first in an intermediate chamber. Therefore, when the ice formation occurs first in the intermediate chamber, water in both-side chambers may be prevented from flowing during the ice formation process, so that a proper water level may be maintained to ensure that the spherical ice is made. 
     In addition, the shield may be provided upward of the thermally-insulating portion to further block the transfer of the flowing cold-air. Therefore, the insulation performance in the specific chamber may be further improved, and the ice-making speed in each of the ice chambers may be controlled even when the cold-air supply is concentrated. 
     Further, according to the present embodiment, the deformation of the upper tray may be prevented by the rib formed along the circumference of the ejector-receiving opening, and thus the interference with the upper ejector during the ice-removal process may be prevented. 
     Further, the shield may have a rib groove corresponding to the rib to prevent interference with the rib, and prevent the rib from interfering with the shield and being deformed. That is, the upper portion of the upper tray maintains its shape to prevent interference with the ejector and ensure the formation of the spherical ice. 
     Further, the shield may include a cut defined therein through which the connection rib connecting the neighboring opening-defining wall passes. The cut widens downward, and a top thereof may be formed to correspond to the thickness of the connection rib. Thus, even when the upper chamber is deformed during the ejecting process, the connection ribs may be led to a wide inlet of the cut, and may be guided along both ends of the inclined cut to return to the original state. In other words, a possibility of poor ice-making due to deformation of the upper tray may be significantly lowered. 
     Further, an additional rib in contact with the periphery of the opening-defining wall, the outer face of the upper tray, and the bottom face of the shield may be further included to prevent the entry of the cold-air through a wide gap of the cut, so that the ice chamber may be further thermally insulated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a refrigerator according to an embodiment of the present disclosure. 
         FIG.  2    is a view showing a state in which a door is opened. 
         FIG.  3    is a partial enlarged view illustrating a state in which an ice maker is mounted according to an embodiment of the present disclosure. 
         FIG.  4    is a partial perspective view illustrating an interior of a freezing compartment according to an embodiment of the present disclosure. 
         FIG.  5    is an exploded perspective view of a grill pan and an ice duct according to an embodiment of the present disclosure. 
         FIG.  6    is a cross-sectional side view of a freezing compartment in a state in which a freezing compartment drawer and an ice bin are retracted therein, according to an embodiment of the present disclosure. 
         FIG.  7    is a partially-cut perspective view of a freezing compartment in a state in which a freezing compartment drawer and an ice bin are extended therefrom. 
         FIG.  8    is a perspective view of an ice maker viewed from above. 
         FIG.  9    is a perspective view of a lower portion of an ice maker viewed from one side. 
         FIG.  10    is an exploded perspective view of an ice maker. 
         FIG.  11    is an exploded perspective view showing a coupling structure of an ice maker and a cover plate. 
         FIG.  12    is a perspective view of an upper casing according to an embodiment of the present disclosure viewed from above. 
         FIG.  13    is a perspective view of an upper casing viewed from below. 
         FIG.  14    is a side view of an upper casing. 
         FIG.  15    is a partial plan view of an ice maker viewed from above. 
         FIG.  16    is an enlarged view of a portion A of  FIG.  15   . 
         FIG.  17    shows flow of cold-air on a top face of an ice maker. 
         FIG.  18    is a perspective view of  FIG.  16    taken along a line  18 - 18 ′. 
         FIG.  19    is a perspective view of an upper tray according to an embodiment of the present disclosure viewed from above. 
         FIG.  20    is a perspective view of an upper tray viewed from below. 
         FIG.  21    is a side view of an upper tray. 
         FIG.  22    is a perspective view of an upper support according to an embodiment of the present disclosure viewed from above. 
         FIG.  23    is a perspective view of an upper support viewed from below. 
         FIG.  24    is a cross-sectional view showing a coupling structure of an upper assembly according to an embodiment of the present disclosure. 
         FIG.  25    is a perspective view of an upper tray according to another embodiment of the present disclosure viewed from above. 
         FIG.  26    is a cross-sectional view of  FIG.  25    taken along a line  26 - 26 ′. 
         FIG.  27    is a cross-sectional view of  FIG.  25    taken along a line  27 - 27 ′. 
         FIG.  28    is a partially-cut perspective view showing a structure of a shield of an upper casing according to another embodiment of the present disclosure. 
         FIG.  29    is a perspective view of a lower assembly according to an embodiment of the present disclosure. 
         FIG.  30    is an exploded perspective view of a lower assembly viewed from above. 
         FIG.  31    is an exploded perspective view of a lower assembly viewed from below. 
         FIG.  32    is a partial perspective view illustrating a protruding confiner of a lower casing according to an embodiment of the present disclosure. 
         FIG.  33    is a partial perspective view illustrating a coupling protrusion of a lower tray according to an embodiment of the present disclosure. 
         FIG.  34    is a cross-sectional view of a lower assembly. 
         FIG.  35    is a cross-sectional view of  FIG.  27    taken along a line  35 - 35 ′. 
         FIG.  36    is a plan view of a lower tray. 
         FIG.  37    is a perspective view of a lower tray according to another embodiment of the present disclosure. 
         FIG.  38    is a cross-sectional view that sequentially illustrates a pivoting state of a lower tray. 
         FIG.  39    is a cross-sectional view showing states of an upper tray and a lower tray immediately before or during ice-making. 
         FIG.  40    shows states of upper and lower trays upon completion of ice-making. 
         FIG.  41    is a perspective view showing a state in which an upper assembly and a lower assembly are closed, according to an embodiment of the present disclosure. 
         FIG.  42    is an exploded perspective view showing a coupling structure of a connector according to an embodiment of the present disclosure. 
         FIG.  43    is a side view showing a disposition of a connector. 
         FIG.  44    is a cross-sectional view of  FIG.  41    taken along a line  44 - 44 ′. 
         FIG.  45    is a cross-sectional view of  FIG.  41    taken along a line  45 - 45 ′. 
         FIG.  46    is a perspective view showing a state in which upper and lower assemblies are open. 
         FIG.  47    is a cross-sectional view of  FIG.  46    taken along a line  47 - 47 ′. 
         FIG.  48    is a side view showing a state of  FIG.  41    viewed from one side. 
         FIG.  49    is a side view showing a state of  FIG.  41    viewed from the other side. 
         FIG.  50    is a front view of an ice maker. 
         FIG.  51    is a partial cross-sectional view showing a coupling structure of an upper ejector. 
         FIG.  52    is an exploded perspective view of a driver according to an embodiment of the present disclosure. 
         FIG.  53    is a partial perspective view showing a driver being moved for provisional fixing of a driver. 
         FIG.  54    is a partial perspective view of a driver, which has been provisionally-fixed. 
         FIG.  55    is a partial perspective view for showing restraint and coupling of a driver. 
         FIG.  56    is a side view of an ice-full state detection lever positioned at a topmost position, which is an initial position, according to an embodiment of the present disclosure. 
         FIG.  57    is a side view of an ice-full state detection lever positioned at a bottommost position, which is a detection position. 
         FIG.  58    is an exploded perspective view showing a coupling structure of an upper casing and a lower ejector according to an embodiment of the present disclosure. 
         FIG.  59    is a partial perspective view showing a detailed structure of a lower ejector. 
         FIG.  60    shows a deformed state of a lower tray when the lower assembly is fully pivoted. 
         FIG.  61    shows a state just before a lower ejector passes through a lower tray. 
         FIG.  62    is a cutaway view taken along a line  62 - 62 ′of  FIG.  8   . 
         FIG.  63    is a view showing a state in which the ice generation is completed in  FIG.  62   . 
         FIG.  64    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    in a water-supplied state. 
         FIG.  65    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    in an ice-making process. 
         FIG.  66    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    in a state in which the ice-making process is completed. 
         FIG.  67    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    at an initial ice-removal state. 
         FIG.  68    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    in a state in which an ice-removal process is completed. 
     
    
    
     DESCRIPTION OF SPECIFIC EMBODIMENTS 
     Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that when components in the drawings are designated by reference numerals, the same components have the same reference numerals as far as possible even though the components are illustrated in different drawings. Further, in description of embodiments of the present disclosure, when it is determined that detailed descriptions of well-known configurations or functions disturb understanding of the embodiments of the present disclosure, the detailed descriptions will be omitted. 
     Also, in the description of the embodiments of the present disclosure, the terms such as first, second, A, B, (a) and (b) may be used. Each of the terms is merely used to distinguish the corresponding component from other components, and does not delimit an essence, an order or a sequence of the corresponding component. It should be understood that when one component is “connected”, “coupled” or “joined” to another component, the former may be directly connected or jointed to the latter or may be “connected”, “coupled” or “joined” to the latter with a third component interposed therebetween. 
       FIG.  1    is a perspective view of a refrigerator according to an embodiment of the present disclosure. Further,  FIG.  2    is a view showing a state in which a door is opened. Further,  FIG.  3    is a partial enlarged view of an ice maker according to an embodiment of the present disclosure. 
     For convenience of description and understanding, directions will be defined. Hereinafter, based on a bottom face on which the refrigerator is installed, a direction toward the bottom face may be referred to as a downward direction, and a direction toward a top face of a cabinet  2 , which is opposite to the bottom face, may be referred to as an upward direction. Further, when an undefined direction is described, the direction may be described by being defined based on each drawing. 
     Referring to  FIGS.  1  to  3   , a refrigerator  1  according to an embodiment of the present disclosure may include a cabinet  2  for defining a storage space therein, and a door for opening and closing the storage space. 
     In detail, the cabinet  2  defines the storage space vertically divided by a barrier. A refrigerating compartment  3  may be defined at an upper portion of the storage space, and a freezing compartment  4  may be defined at a lower portion of the storage space. 
     An accommodation member such as a drawer, a shelf, a basket, and the like may be disposed in each of the refrigerating compartment  3  and the freezing compartment  4 . 
     The door may include a refrigerating compartment door  5  shielding the refrigerating compartment  3  and a freezing compartment door  6  shielding the freezing compartment  4 . 
     The refrigerating compartment door  5  includes a pair of left and right doors, which may be opened and closed by pivoting. Further, the freezing compartment door  6  may be disposed to be retractable or extendable like a drawer. 
     In another example, the arrangement of the refrigerating compartment  3  and the freezing compartment  4  and the shape of the door may be changed based on kinds of the refrigerators. However, the present disclosure may not be limited thereto, and may be applied to various kinds of refrigerators. For example, the freezing compartment  4  and the refrigerating compartment  3  may be arranged horizontally, or the freezing compartment  4  may be disposed above the refrigerating compartment  3 . 
     In one example, one of the pair of refrigerating compartment doors  5  on both sides may have an ice-making chamber  8  defined therein for receiving a main ice maker  81 . The ice-making chamber  8  may receive cold-air from an evaporator (not shown) in the cabinet  2  to allow ice to be made in the main ice maker  81 , and may define an insulated space together with the refrigerating compartment  3 . In another example, depending on a structure of the refrigerator, the ice-making chamber may be defined inside the refrigerating compartment  3  rather than the refrigerating compartment door  5 , and the main ice maker  81  may be disposed inside the ice-making chamber. 
     A dispenser  7  may be disposed on one side of the refrigerating compartment door  5 , which corresponds to a position of the ice-making chamber  8 . The dispenser  7  may be capable of dispensing water or ice, and may have a structure in communication with the ice-making chamber  8  to enable dispensing of ice made in the ice maker  81 . 
     In one example, the freezing compartment  4  may be equipped with an ice maker  100 . The ice maker  100 , which makes ice using water supplied, may produce ice in a spherical shape. The ice maker  100  may be referred to as an auxiliary ice maker because the ice maker  100  usually generates less ice than the main ice maker  81  or is used less than the main ice maker  81 . 
     The freezing compartment  4  may be equipped with a duct  44  for supplying cold-air to the freezing compartment  100 . Thus, a portion of the cold-air generated in the evaporator and supplied to the freezing compartment  4  may be flowed toward the ice maker  100  to make ice in an indirect cooling manner. 
     Further, an ice bin  102  in which the made ice is stored after being transferred from the ice maker  100  may be further provided below the ice maker  100 . Further, the ice bin  102  may be disposed in a freezing compartment drawer  41  which is extended from the freezing compartment  4 . Further, the ice bin  102  may be configured to be retracted and extended together with the freezing compartment drawer  41  to allow a user to take out the stored ice. 
     Thus, the ice maker  100  and the ice bin  102  may be viewed as at least a portion of which is received in the freezing compartment drawer  41 . Further, a large portion of the ice maker  100  and the ice bin  102  may be hidden when viewed from the outside. Further, the ice stored in the ice bin  102  may be easily taken out by the retraction and extension of the freezing compartment drawer  41 . 
     In another example, the ice made in the ice maker  100  or the ice stored in the ice bin  102  may be transferred to the dispenser  7  by transfer means and dispensed through the dispenser  7 . 
     In another example, the refrigerator  1  may not include the dispenser  7  and the main ice maker  81 , but include only the ice maker  1 . The ice maker  100  may be disposed in the ice-making chamber  8  in place of the main ice maker  81 . 
     Hereinafter, the mounting structure of the ice maker  100  will be described in detail with reference to the accompanying drawings. 
     Hereinafter, a mounting structure of the ice maker  100  will be described in detail with reference to the accompanying drawings. 
       FIG.  4    is a partial perspective view illustrating an interior of a freezing compartment according to an embodiment of the present disclosure. Further,  FIG.  5    is an exploded perspective view of a grill pan and an ice duct according to an embodiment of the present disclosure. 
     As shown in  FIGS.  4  and  5   , the storage space inside the cabinet  2  may be defined by an inner casing  21 . Further, the inner casing  21  defines the vertically divided storage space, that is, the refrigerating compartment  3  and freezing compartment  4 . 
     A portion of a top face of the freezing compartment  4  may be opened, and a mounting cover  43  may be formed at a position corresponding to a position where the ice maker  100  is mounted. The mounting cover  43  may be coupled and fixed to the inner casing  21 , and define a space further recessed upwardly from the top face of the freezing compartment  4  to secure a space in which the ice maker  100  is disposed. Further, the mounting cover  43  may include a structure for fixing and mounting the ice maker  100 . 
     Further, the mounting cover  43  may further include a cover recess  431  defined therein, which may be further recessed upwards to receive an upper ejector  300  to be described below. Since the upper ejector  300  has a structure that protrudes upward from the top face of the ice maker  100 , the upper ejector  300  may be received in the cover recess  431  to minimize a space used by the ice maker  100 . 
     Further, the mounting cover  43  may have a water-supply hole  432  defined therein for supplying water to the ice maker  100 . Although not shown, a pipe for supplying the water toward the ice maker  100  may penetrate the water-supply hole  432 . Further, an electrical-wire in connection with the ice maker  100  may pass through the mounting cover  43 . Further, because of the connector connected to the electrical-wire, the ice maker  100  may be in a state of being electrically connected and being able to be powered. 
     A rear wall face of the freezing compartment  4  may be formed by a grill pan  42 . The grill pan  42  may divide the space in the inner casing  21  horizontally, and may define, at rearward of the freezing compartment, a space for receiving an evaporator (not shown) that generates the cold-air and a blower fan (not shown) that circulates the cold-air therein. 
     The grill pan  42  may include cold-air ejectors  421  and  422  and a cold-air absorber  423 . Thus, the cold-air ejectors  421  and  422  and the cold-air absorber  423  may allow air circulation between the freezing compartment  4  and the space in which the evaporator is placed, and may cool the freezing compartment  4 . The cold-air ejectors  421  and  422  may be formed in a grill shape. The cold-air may be evenly discharged into the freezing compartment  4  through the upper cold-air ejector  421  and the lower cold-air ejector  422 . 
     In particular, the upper cold-air ejector  421  may be disposed at a top of the freezing compartment  4 . Further, the cold-air discharged from the upper cold-air ejector  421  may be used to cool the ice maker  100  and the ice bin  102  arranged at an upper portion of the freezing compartment  4 . In particular, the upper cold-air ejector  421  may include the cold-air duct  44  for supplying the cold-air to the ice maker  100 . 
     The cold-air duct  44  may connect the upper cold-air ejector  421  to the cold-air hole  134  of the ice maker  100 . That is, the cold-air duct  44  may connect the upper cold-air ejector  421  located at a center of the freezing compartment  4  in the horizontal direction and the ice maker  100  located at an upper end of the freezing compartment  4 , so that a portion of the cold-air discharged from the upper cold-air ejector 421  may be supplied directly into the ice maker  100 . 
     The cold-air duct  44  may be disposed at one end of the upper cold-air ejector  421  which extends in the horizontal direction. That is, the cold-air discharged from the upper cold-air ejector  421  is discharged to the freezing compartment  4 , and cold-air discharged from one side close to the cold-air duct  44  of the cold-air may be directed to the ice maker  100  through the cold-air duct  44 . 
     Thus, a rear end of the cold-air duct  44  may be recessed to receive one end of the upper cold-air ejector 421 . Further, an opened rear face of the cold-air duct  44  may be shaped in a shape corresponding to a shape of the grill pan  42 , and may be in contact with the grill pan  42  to prevent the cold-air from leaking. Further, a coupled portion  444  may be formed at a rear end of the cold-air duct  44 , and may be fixed to a front face of the grill pan  42  by a screw. 
     A cross-section of the cold-air duct  44  may decrease forwardly. Further, a duct outlet  446  on a front face of the cold-air duct  44  may be inserted into the cold-air hole  134  to concentrically supply the cold-air into the ice maker  100 . 
     In one example, the cold-air duct  44  may be constituted by an upper duct  443  forming an upper portion of the cold-air duct  44  and a lower duct  442  forming a lower portion of the cold-air duct  44 , and may define a whole cold-air passage by coupling of the upper duct  443  and the lower duct  442 . Further, the upper duct  443  and lower duct  442  may be coupled to each other by a connector  443 . The connector  443 , which has a hooking structure like a hook, may be formed on each of the upper duct  443  and the lower duct  442 . 
       FIG.  6    is a cross-sectional side view of a freezing compartment in a state in which a freezing compartment drawer and an ice bin are retracted therein, according to an embodiment of the present disclosure. Further,  FIG.  7    is a partially-cut perspective view of a freezing compartment in a state in which a freezing compartment drawer and an ice bin are extended therefrom. 
     As shown in the drawings, the ice maker  100  may be mounted on the top face of the freezing compartment  4 . That is, the upper casing  120 , which forms an outer shape of the ice maker  100 , may be mounted on the mounting cover  43 . 
     In one example, the refrigerator  1  is installed to be tilted such that a front end of the cabinet  2  is slightly higher than a rear end thereof, so that the door  6  may be closed by a self weight after opening. Thus, the top face of the freezing compartment  4  may also be tilted relative to a ground on which the refrigerator  1  is installed, at the same slope as the cabinet  2 . 
     In this connection, when the ice maker  100  is mounted flush with the top face of the freezing compartment  4 , a water level of the water supplied inside the ice maker  100  may also be tilted, which may result in a problem of a difference in a size of ice cubes respectively made in the chambers. In particular, in a case of the ice maker  100  according to the present embodiment for making the spherical ice, when the water level is tilted, amounts of water received in the chambers are different from each other, so that a uniform spherical ice may not be made. 
     In order to avoid such problems, the ice maker  100  may be mounted to be tilted relative to the top face of the freezing compartment  4 , that is, based on top and bottom faces of the cabinet  2 . In detail, the ice maker  100  may be mounted to be in a state in which the top face of the upper casing  120  is rotated counterclockwise (when viewed in  FIG.  6   ) by a set angle a based on the top face of the freezing compartment  4  or the top face of the mounting cover  43 . In this connection, the set angle a may be equal to the slope of the cabinet  2 , and may be approximately 0.7° to 0.8°. Further, the front end of the upper casing  120  may be approximately 3 mm to 5 mm lower than the rear end thereof. 
     In a state of being mounted in the freezing compartment  4 , the ice maker  100  may be tilted by the set angle a, so that the ice maker  100  may be horizontal to the ground on which the refrigerator  1  is installed. Thus, the level of the water supplied into the ice maker  100  may become level with the ground, and the same amount of water may be received in the plurality of chambers to make ice of uniform size. 
     Further, in a state in which the ice maker  100  is mounted, the cold-air hole  134  at the rear end of the upper casing  120  may be connected to the upper cold-air ejector  421 . Thus, the cold-air for the ice-making may be concentrically supplied to an inner upper portion of the upper casing  120  to increase an ice-making efficiency. 
     In one example, the ice bin  102  may be mounted inside the freezing compartment drawer  41 . The ice bin  102  is positioned correctly below the ice maker  100  in a state in which the freezing compartment drawer  41  is retracted. To this end, the freezing compartment drawer  41  may have a bin mounting guide  411  which guides a mounting position of the ice bin  102 . The bin mounting guides  411  may respectively protrude upwardly from positions corresponding to four corners of the bottom face of the ice bin  102 , and may be arranged to enclose the four corners of the bottom face of the ice bin  102 . Thus, the ice bin  102  may remain in position in a state of being mounted in the freezing compartment drawer  41 , and may be positioned vertically below the ice maker  100  in a state in which the freezing compartment drawer  41  is retracted. 
     As shown in  FIG.  6   , a bottom of the ice maker  100  may be received inside the ice bin  102  in a state in which the freezing compartment drawer  41  is retracted. That is, the bottom of the ice maker  100  may be located inside the ice bin  102  and the freezing compartment drawer  41 . Thus, the ice removed from the ice maker  100  may fall and be stored in the ice bin  102 . Further, a volume loss inside the freezing compartment  4  due to arrangement of the ice maker  100  and the ice bin  102  may be minimized by minimizing the space between the ice maker  100  and the ice bin  102 . In another example, the bottom of the ice maker  100  and the bottom face of the ice bin  102  may be spaced apart each other by an appropriate distance to ensure a distance for storing an appropriate amount of ice. 
     In one example, in a state in which the ice maker  100  is mounted therein, the freezing compartment drawer  41  may be extended or retracted as shown in  FIG.  7   . Further, in this connection, at least a portion of rear faces of the ice bin  102  and the freezing compartment drawer  41  may be opened to prevent interference with the ice maker  100 . 
     In detail, a drawer opening  412  and a bin opening  102   a  may be respectively defined in the rear faces of the freezing compartment drawer  41  and the ice bin  102  corresponding to the position of the ice maker  100 . The drawer opening  412  and the bin opening  102   a  may be respectively defined at positions facing each other. Further, the drawer opening  412  and the bin opening  102   a  may be respectively defined to open from the top of the freezing compartment drawer  41  and the top of the ice bin  102  to positions lower than the bottom of the ice maker  100 . 
     Thus, even when the freezing compartment drawer  41  is extended in a state in which the ice maker  100  is mounted therein, the ice maker  100  may be prevented from interfering with the ice bin  102  and the freezing compartment drawer  41 . 
     In particular, even in a state in which the ice maker  100  removes the ice and the lower assembly  200  is pivoted, or in a state in which an ice-full state detection lever  700  is rotated to detect an ice-full state, the drawer opening  412  and the bin opening  102   a  may be in a shape of being recessed further downward from the bottom of the ice maker  100  to prevent interference with the freezing compartment drawer  41  or the ice bin  102 . 
     A drawer opening guide  412   a  extending rearward along a perimeter of the drawer opening  412  may be formed. The drawer opening guide  412   a  may extend rearward to guide the cold-air flowing downward from the upper cold-air ejector 421  into the freezing compartment drawer  41 . 
     Further, a bin opening guide  102   b  extending rearward along a perimeter of the bin opening  102   a  may be included. The cold-air flowing downward from the upper cold-air ejector  421  may flow into the ice bin  102  through the bin opening guide  102   b.    
     In one example, a cover casing  130  in a plate shape may be disposed on a rear face of the upper casing  120  of the ice maker  100 . The cover plate  130  may be formed to cover at least a portion of the ice bin opening  102   a  such that the ice inside the ice bin  102  does not fall downward through the bin opening  102   a  and the drawer opening  412 . 
     The cover plate  130  extends downward from a rear face of the upper casing  120  of the ice maker  100  and may extend into the bin opening  102   a . As shown in  FIG.  6   , in a state in which the freezing compartment drawer  41  is retracted, the cover plate  130  is positioned inside the bin opening  102   a  to cover at least a portion of the bin opening  102   a . Thus, even when the ice is moved backwards by inertia at the moment the freezing compartment drawer  41  is extended or retracted, the ice may be blocked by the cover plate  130 , and prevented from falling out of the ice bin  102 . 
     Further, the cover plate  130  may have a plurality of openings defined therein to allow the cold-air to pass therethrough. Thus, in a state in which the freezing compartment drawer  41  is closed as shown in  FIG.  6   , the cold-air may pass through the cover plate  130  and flow into the ice bin  102 . 
     The cover plate  130  may be formed to have a size for not interfering with the drawer opening  412  and the bin opening  102   a . Thus, the cover plate  130  may not interfere with the freezing compartment drawer  41  or the ice bin  102  when the freezing compartment drawer  41  is extended as shown in  FIG.  7   . 
     The cover plate  130  may be molded separately and joined to the upper casing  120  of the ice maker  100 . Alternatively, the rear face of the upper casing  120  may protrude further downward to form the cover plate  130 . 
     Hereinafter, the ice maker  100  will be described in detail with reference to the accompanying drawings. 
       FIG.  8    is a perspective view of an ice maker viewed from above. Further,  FIG.  9    is a perspective view of a lower portion of an ice maker viewed from one side. Further,  FIG.  10    is an exploded perspective view of an ice maker. 
     Referring to  FIGS.  8  to  10   , the ice maker  100  may include an upper assembly  110  and a lower assembly  200 . 
     The lower assembly  200  may be fixed to the upper assembly  110  such that one end thereof is pivotable. The pivoting may open and close an inner space defined by the lower assembly  200  and the upper assembly  110 . 
     In detail, the lower assembly  200  may make the spherical ice together with the upper assembly  110  in a state in which the lower assembly  200  is in close contact with the upper assembly  110 . 
     That is, the upper assembly  110  and the lower assembly  200  define an ice chamber  111  for making the spherical ice. The ice chamber  111  is substantially a spherical chamber. The upper assembly  110  and the lower assembly  200  may define a plurality of divided ice chambers  111 . Hereinafter, an example in which three ice chambers  111  are defined by the upper assembly  110  and the lower assembly  200  will be described. Note that there is no limit to the number of ice chambers  111 . 
     In a state in which the upper assembly  110  and the lower assembly  200  define the ice chamber  111 , the water may be supplied to the ice chamber  111  via a water supply  190 . The water supply  190  is coupled to the upper assembly  110 , and direct the water supplied from the outside to the ice chamber  111 . 
     After the ice is made, the lower assembly  200  may pivot in a forward direction. Then, the spherical ice made in the space between the upper assembly  110  and the lower assembly  200  may be separated from the upper assembly  110  and the lower assembly  200 , and may fall to the ice bin  102 . 
     In one example, the ice maker  100  may further include a driver  180  such that the lower assembly  200  is pivotable relative to the upper assembly  110 . 
     The driver  180  may include a driving motor and a power transmission for transmitting power of the driving motor to the lower assembly  200 . The power transmission may include at least one gear, and may provide a suitable torque for the pivoting of the lower assembly  200  by a combination of the plurality of gears. Further, the ice-full state detection lever  700  may be connected to the driver  180 , and the ice-full state detection lever  700  may be rotated by the power transmission. 
     The driving motor may be a bidirectionally rotatable motor. Thus, bidirectional pivoting of the lower assembly  200  and ice-full state detection lever  700  is achieved. 
     The ice maker  100  may further include an upper ejector  300  such that the ice may be separated from the upper assembly  110 . The upper ejector  300  may cause the ice in close contact with the upper assembly  110  to be separated from the upper assembly  110 . 
     The upper ejector  300  may include an ejector body  310  and at least one ejecting pin  320  extending in a direction intersecting the ejector body  310 . The ejecting pin  320  may include ejecting pins of the same number as the ice chamber  111 , and each ejecting pin may remove ice made in each ice chamber  111 . 
     The ejecting pin  320  may press the ice in the ice chamber  111  while passing through the upper assembly  110  and being inserted into the ice chamber  111 . The ice pressed by the ejecting pin  320  may be separated from the upper assembly  110 . 
     Further, the ice maker  100  may further include a lower ejector  400  such that the ice in close contact with the lower assembly  200  may be separated therefrom. The lower ejector  400  may press the lower assembly  200  such that the ice in close contact with the lower assembly  200  is separated from the lower assembly  200 . 
     An end of the lower ejector  400  may be located within a pivoting range of the lower assembly  200 , and may press an outer side of the ice chamber  111  to remove the ice in the pivoting process of the lower assembly  200 . The lower ejector  400  may be fixedly mounted to the upper casing  120 . 
     In one example, a pivoting force of the lower assembly  200  may be transmitted to the upper ejector  300  in the pivoting process of the lower assembly  200  for ice-removal. To this end, the ice maker  100  may further include a connector  350  connecting the lower assembly  200  and the upper ejector  300  with each other. The connector  350  may include at least one link. 
     In one example, the connector  350  may include rotating arms  351  and  352  and a link  356 . The rotating arms  351  and  352  may be connected to the driver  180  together with the lower support  270  and rotated together. Further, ends of the rotating arms  351  and  352  may be connected to the lower support  270  by an elastic member  360  to be in close contact with the upper assembly  110  in a state in which the lower assembly  200  is closed. 
     The link  356  connects the lower support  270  with the upper ejector  300 , so that the pivoting force of the lower support  270  may be transmitted to the upper ejector  300  when the lower support  270  pivots. The upper ejector  300  may move vertically in association with the pivoting of the lower support  270  by the link  356 . 
     In one example, when the lower assembly  200  pivots in the forward direction, the upper ejector  300  may descend by the connector  350 , so that the ejecting pin  320  may press the ice. On the other hand, during when the lower assembly  200  pivots in a reverse direction, the upper ejector  300  may ascend by the connector  350  to return to an original position thereof. 
     Hereinafter, the upper assembly  110  and the lower assembly  200  will be described in more detail. 
     The upper assembly  110  may include an upper tray  150  that forms an upper portion of the ice chamber  111  for making the ice. Further, the upper assembly  110  may further include the upper casing  120  and an upper support  170  to fix the upper tray  150 . 
     The upper tray  150  may be positioned below the upper casing  120 , and the upper support  170  may be positioned below the upper tray  150 . As such, the upper casing  120 , the upper tray  150 , and the upper support  170  may be arranged in the vertical direction one after the other, and may be fastened by a fastener and formed as a single assembly. That is, the upper tray  150  may be fixedly mounted between the upper casing  120  and the upper support  170  by the fastener. Thus, the upper tray  150  may be maintained at a fixed position, and may be prevented from being deformed or separated from the upper assembly  110 . 
     In one example, the water supply  190  may be disposed at an upper portion of the upper casing  120 . The water supply  190  is for supplying the water into the ice chamber  111 , which may be disposed to face the ice chamber  111  from above the upper casing  120 . 
     Further, the ice maker  100  may further include a temperature sensor  500  for sensing a temperature of the water or the ice in the ice chamber  111 . The temperature sensor  500  may indirectly sense the temperature of the water or the ice in the ice chamber  111  by sensing a temperature of the upper tray  150 . 
     The temperature sensor  500  may be mounted on the upper casing  120 . Further, at least a portion of the temperature sensor  500  may be exposed through the opened side of the upper casing  120 . 
     In one example, the lower assembly  200  may include a lower tray  250  that forms a lower portion of the ice chamber  111  for making the ice. Further, the lower assembly  200  may further include a lower support  270  supporting a lower portion of the lower tray  250  and a lower casing  210  covering an upper portion of the lower tray  250 . 
     The lower casing  210 , lower tray  250 , and the lower support  270  may be arranged in the vertical direction one after the other, and may be fastened by a fastener and formed as a single assembly. 
     In one example, the ice maker  100  may further include a switch  600  for turning the ice maker  100  on or off. The switch  600  may be disposed on a front face of the upper casing  120 . Further, when the user manipulates the switch  600  to be turned on, the ice may be made by the ice maker  100 . That is, when the switch  600  is turned on, operations of components, including the ice maker, for ice-making may be started. That is, when the switch  600  is turned on, the water is supplied to the ice maker  100 , and an ice-making process in which the ice is made by the cold-air and an ice-removal process in which the lower assembly  200  is pivoted and the ice is removed may be repeatedly performed. 
     On the other hand, when the switch  600  is manipulated to be turned off, the components for the ice-making, including the ice maker  100 , will remain inactive and will not be able to made the ice through the ice maker  100 . 
     Further, the ice maker  100  may further include the ice-full state detection lever  700 . The ice-full state detection lever  700  may detect whether the ice bin  102  is in the ice-full state while receiving the power of the driver  180  and rotating. 
     One side of the ice-full state detection lever  700  may be connected to the driver  180  and the other side of the ice-full state detection lever  700  may be rotatably connected to the upper casing  120 , so that the ice-full state detection lever  700  may rotate based on the operation of the driver  180 . 
     The ice-full state detection lever  700  may be positioned below an axis of rotation of the lower assembly  200 , so that the ice-full state detection lever  700  does not interfere with the lower assembly  200  during the rotation of the lower assembly  200 . Further, both ends of the ice-full state detection lever  700  may be bent many times. The ice-full state detection lever  700  may be rotated by the driver  180 , and may detect whether a space below the lower assembly  200 , that is, the space inside the ice bin  102  is in the ice-full state. 
     In one example, an internal structure of the driver  180  is not shown in detail, but will be briefly described for the operation of the ice-full state detection lever  700 . The driver  180  may further include a cam rotated by the rotational power of the motor and a moving lever moving along a cam face. A magnet may be provided on the moving lever. The driver  180  may further include a hall sensor that may detect the magnet when the moving lever moves. 
     A first gear to which the ice-full state detection lever  720  is engaged among a plurality of gears of the driver  180  may be selectively engaged with or disengaged from a second gear that engages with the first gear. In one example, the first gear is elastically supported by the elastic member, so that the first gear may be engaged with the second gear when no external force is applied thereto. 
     On the other hand, when a resistance greater than an elastic force of the elastic member is applied to the first gear, the first gear may be spaced apart from the second gear. 
     A case in which the resistance greater than the elastic force of the elastic member is applied to the first gear is, for example, a case in which the ice-full state detection lever  700  is caught in the ice in the ice-removal process (in the case of the ice-full state). In this case, the first gear may be spaced apart from the second gear, so that breakage of the gears may be prevented. 
     The ice-full state detection lever  700  may be rotated together in association with the lower assembly  200  by the plurality of gears and the cam. In this connection, the cam may be connected to the second gear or may be linked to the second gear. 
     Depending on whether the hall sensor senses the magnet, the hall sensor may output first and second signals that are different outputs. One of the first signal and the second signal may be a high signal, and the other may be a low signal. 
     The ice-full state detection lever  700  may be rotated from a standby position to an ice-full state detection position for the ice-full state detection. Further, the ice-full state detection lever  700  may identify whether the ice bin  102  is filled with the ice of equal to or greater than the predetermined amount while passing through an inner portion of the ice bin  102  in the rotation process. 
     Hereinafter, the ice-full state detection lever  700  will be described in more detail with reference to  FIG.  10   . 
     The ice-full state detection lever  700  may be a lever in a form of a wire. That is, the ice-full state detection lever  700  may be formed by bending a wire having a predetermined diameter a plurality of times. 
     The ice-full state detection lever  700  may include a detection body  710 . The detection body  710  may pass a position of a set vertical level inside the ice bin  102  in the rotation process of the ice-full state detection lever  700 , and may be substantially the lowest portion of the ice-full state detection lever  700 . 
     Further, the ice-full state detection lever  700  may be positioned such that an entirety of the detection body  710  is located below the lower assembly  200  to prevent the interference between the lower assembly  220  and the detection body  710  in the pivoting process of the lower assembly  200 . 
     The detection body  710  may be in contact with the ice in the ice bin  102  in the ice-full state of the ice bin  102 . The ice-full state detection lever  700  may include the detection body  710 . The detection body  710  may extend in a direction parallel to a direction of extension of the connection shaft  370 . The detection body  710  may be positioned lower than a lowest point of the lower assembly  200  regardless of the position. 
     Further, the ice-full state detection lever  700  may include a pair of extensions  720  and  730  respectively extending upward from both ends of the detection body  710 . The pair of extensions  720  and  730  may extend substantially in parallel with each other. 
     A distance between the pair of extensions  720  and  730 , that is, a length of the detection body  710  may be larger than a horizontal length of the lower assembly  200 . Thus, in the rotation process of the ice-full state detection lever  700  and the pivoting process of the lower assembly  200 , the pair of extensions  720  and  730  and the detection body  710  may be prevented from interfering with the lower assembly  200 . 
     The pair of extensions  720  and  730  may include a first extension  720  extending to a lever receiving portion  187  of the driver  180  and a second extension  710  extending to the lever receiving hole  120   a  of the upper casing  120 . The pair of extensions  720  and  730  may be bent at least once, so that the ice-full state detection lever  700  is not deformed even after repeated contact with the ice and maintains a more reliable detection state. 
     For example, the extensions  720  and  730  may include a first bent portion  721  extending from each of both ends of the detection body  710  and a second bent portions  722  extending from each of ends of the first bent portions  721  to the driver  180 . Further, the first bent portion  721  and second bent portion  722  may be bent at a predetermined angle. The first bent portion  721  and the second bent portion  722  may intersect with each other at an angle in a range approximately from 140° to 150°. Further, a length of the first bent portion  721  may be larger than a length of the second bent portion  722 . Due to such structure, the ice-full state detection lever  700  may reduce a radius of rotation, and may detect the ice in the ice bin  102  while minimizing interference with other components. 
     Further, a pair of inserted portions  740  and  750 , which are respectively bent outwardly, may be formed at top of the pair of extensions  720  and  730 , respectively. The pair of inserted portions  740  and  750  may include a first inserted portion  740  that is bent at the end of the first extension  720  and inserted into the lever receiving portion  187  and a second inserted portion  750  that is bent at the end of the second extension  710  and inserted into the lever receiving hole  120   a . The first inserted portion  740  and second inserted portion  750  may be formed to be respectively coupled to and rotatably inserted into the lever receiving portion  187  and the lever receiving hole  120   a.    
     That is, the first inserted portion  740  may be coupled to the driver  180  and rotated by the driver  180 , and the second inserted portion  750  may be rotatably coupled to the lever receiving hole  120   a . Thus, the ice-full state detection lever  700  may be rotated based on the operation of the driver  180 , and may detect whether the ice bin  102  is in the ice-full state. 
     In one example, the ice maker  100  may be equipped with the cover plate  130 . 
     Hereinafter, a structure of the cover plate  130  will be described in detail with reference to the accompanying drawings. 
       FIG.  11    is an exploded perspective view showing a coupling structure of an ice maker and a cover plate. 
     Referring to  FIGS.  6 ,  7 , and  11   , the lever receiving hole  120   a  may be defined in one face of the upper casing  120 , and a pair of bosses  120   b  may respectively protrude from both left and right sides of the lever receiving hole  120   a . Further, a stepped plate seat  120   c  may be formed above the pair of bosses  120   b . In this connection, one face of the upper casing  120  in which the lever receiving hole  120   a  is defined and on which the plate seat  120   c  is formed is a face adjacent to the rear face of the freezing compartment  4  as shown in  FIGS.  6  and  7   . Further, the cover plate  130  may be coupled to said one face of the upper casing  120 . 
     The cover plate  130  may be formed in a rectangular plate shape, and may be formed to have a width corresponding to a width of the upper casing  120 . Further, the cover plate  130  extends further below the bottom of the upper casing  120 , and may extend to cover a large portion of the bin opening  102   a  when the freezing compartment drawer  41  is closed. 
     A plate bent portion  130   d  may be formed at a top of the cover plate  130 , and the plate bent portion  130   d  may be seated on the plate seat  120   c . Further, the cover plate  130  may be formed with an exposing opening  130   c  defined therein exposing the lever receiving hole  120   a  and the second inserted portion  750 . The second inserted portion  750  is not interfered by the exposing opening  130   c  when the ice-full state detection lever  700  is rotated, thereby ensuring the operation of the ice-full state detection lever  700 . 
     Further, boss-receiving portions  130   b  may protrude from left and right sides of the exposing opening  130   c , respectively. The boss-receiving portions  130   b  are shaped to respectively accommodate the pair of the bosses  120   b  protruding from the upper casing  120 . 
     Further, the boss-receiving portion  130   b  and the boss  120   b  may be coupled with each other by a fastener such as the screw fastened to the boss-receiving portion  130   b , and the cover plate  130  may be fixed. 
     In one example, a plurality of ventilation holes  130   a  may be defined at a lower portion of the cover plate  130 . The ventilation holes  130   a  may be defined in series, and the lower portion of the cover plate  130  may be shaped like a grill. The ventilation hole  130   a  may extend vertically, and may extend from a bottom of the upper casing  120  to a bottom of the cover plate  130 . Therefore, the cold-air may be smoothly flowed into the ice bin  102  by the ventilation holes  130   a.    
     Further, the cover plate  130  may be formed with a plate rib  130   e.    
     The plate rib  130   e  is for reinforcing the cover plate  130 , which may be formed along the perimeter of the cover plate  130 . Further, the plate rib  130   e  may be formed to cross the cover plate  130  and may be formed between the ventilation holes  130   a.    
     A sufficient strength of the cover plate  130  may be ensured by the plate rib  130   e . Thus, when the freezing compartment drawer  41  is extended and retracted to be opened and closed, the cover plate  130  may prevent the ice inside the ice bin  102  from rolling and passing through the bin opening  102   a . In this connection, the cover plate  130  may not be deformed or damaged from an impact of the ice. 
     The ice made in the present embodiment, which is substantially spherical or nearly spherical in shape, inevitably rolls or moves inside the ice bin  102 . Accordingly, such structure of the cover plate  130  may prevent the spherical ice from falling out of the ice bin  102 . Further, the cover plate  130  is formed so as not to block the flow of the cold-air into the ice bin  102 . 
     In one example, the cover plate  130  may be molded separately and mounted on the upper casing  120 . In another example, if necessary, one side of the upper casing  120  may be extended to have a shape corresponding to that of the cover plate  130 . 
     Hereinafter, a structure of the upper casing  120  constituting the ice maker  100  will be described in detail with reference to the accompanying drawings. 
       FIG.  12    is a perspective view of an upper casing according to an embodiment of the present disclosure viewed from above. Further,  FIG.  13    is a perspective view of an upper casing viewed from below. Further,  FIG.  14    is a side view of an upper casing. 
     Referring to  FIGS.  12  to  14   , the upper casing  120  may be fixedly mounted to the top face of the freezing compartment  4  in a state in which the upper tray  150  is fixed. 
     The upper casing  120  may include an upper plate  121  for fixing the upper tray  150 . The upper tray  150  may be disposed on a bottom face of the upper plate  121 , and the upper tray  150  may be fixed to the upper plate  121 . The upper plate  121  may have a tray opening  123  defined therein through which a portion of the upper tray  150  passes. Further, a portion of a top face of the upper tray  150  may pass through the tray opening  123  and exposed. The tray opening  123  may be defined along an array of the plurality of ice chambers  111 . 
     The upper plate  121  may include a cavity  122  recessed downwardly from the upper plate  121 . A tray opening  123  may be defined in a bottom  122   a  of the cavity  122 . 
     When the upper tray  150  is mounted on the upper plate  121 , a portion of the top face of the upper tray  150  may be located inside the space where the cavity  122  is defined, and may pass through the tray opening  123  and protrude upward. 
     A heater-mounted portion  124  in which an upper heater  148  for heating the upper tray  150  for ice-removal may be defined in the upper casing  120 . The heater-mounted portion may be defined in the bottom of the cavity  122 . 
     Further, the upper casing  120  may further include a pair of sensor-fixing ribs  128  and  129  for mounting the temperature sensor  500 . The pair of sensor-fixing ribs  128  and  129  may be spaced apart from each other, and the temperature sensor  500  may be located between the pair of sensor-fixing ribs  128  and  129 . The pair of sensor-fixing ribs  128  and  129  may be provided on the upper plate  121 . 
     The upper plate  121  may have a plurality of slots  131  and a plurality of slots  132  defined therein for coupling with the upper tray  150 . Portions of the upper tray  150  may be inserted into the plurality of slots  131  and the plurality of slots  132 . The plurality of slots  131  and the plurality of slots  132  may include a first upper slot  131  and a second upper slot  132  positioned opposite to the first upper slot  131  around the tray opening  123 . 
     The first upper slot  131  and the second upper slot  132  may be arranged to face each other, and the tray opening  123  may be located between the first upper slot  131  and the second upper slot  132 . 
     The first upper slot  131  and the second upper slot  132  may be spaced apart from each other with the tray opening  123  therebetween. Further, each of the plurality of the first upper slots  131  and each of the plurality of second upper slots  132  may be spaced apart from each other along a direction in which the ice chambers  111  are successively arranged. 
     The first upper slot  131  and the second upper slot  133  may be defined in a curved shape. Thus, the first upper slot  131  and second upper slot  132  may be defined along a periphery of the ice chamber  111 . Such structure may allow the upper tray  150  to be more firmly fixed to the upper casing  120 . In particular, deformation of dropout of the upper tray  150  may be prevented by fixing the periphery of the ice chamber  111  of the upper tray  150 . 
     A distance from the first upper slot  131  to the tray opening  123  may differ from a distance from the second upper slot  132  to the tray opening  123 . In one example, the distance from the second upper slot  132  to the tray opening  123  may be shorter than the distance from the first upper slot  131  to the tray opening  123 . 
     The upper plate  121  may further include a sleeve  133  for inserting a coupling boss  175  of the upper support  170  to be described later therein. The sleeve  133  may be formed in a cylindrical shape, and may extend upward from the upper plate  121 . 
     In one example, a plurality of sleeves  133  may be arranged on the upper plate  121 . The plurality of sleeves  133  may be arranged successively in the extending direction of the tray opening, and may be spaced apart from each other at a regular interval. 
     Some of the plurality of sleeves  133  may be positioned between two adjacent first upper slots  131 . Some of the remaining sleeves  133  may be positioned between two adjacent second upper slots  132  or may be positioned to face a region between the two second upper slots  132 . Such structure may allow the coupling between the first upper slot  131  and the second upper slot  132  and the protrusions of the upper tray  150  to be very tight. 
     The upper casing  120  may further include a plurality of hinge supports  135  and  136  to allow the lower assembly  200  to pivot. Further, a first hinge hole  137  may be defined in each of the hinge supports  135  and  136 . The plurality of hinge supports  135  and  136  may be spaced apart from each other, so that both ends of the lower assembly  200  may be pivotably coupled to the plurality of hinge supports  135  and  136 . 
     The upper casing  120  may include through-openings  139   b  and  139   c  defined therein for a portion of the connector  350  to pass therethrough. In one example, the links  356  located on both sides of the lower assembly  200  may pass through the through-openings  139   b  and  139   c , respectively. 
     In one example, the upper casing  120  may be formed with a horizontal extension  142  and a vertical extension  140 . The horizontal extension  142  may form the top face of the upper casing  120 , and may be brought to be in contact with the top face of the freezing compartment  4 , the inner casing  21 . In another example, the horizontal extension  142  may be brought to be in contact with the mounting cover  43  rather than inner casing  21 . 
     The horizontal extension  142  may be provided with a hook  138  and a threaded portion  142   a  for fixedly mounting the upper casing  120  to the inner casing  21  or the mounting cover  43 . 
     The hook  138  may be formed on each of both rear ends of the horizontal extension  142 , and may be configured to be fastened to the inner casing  21  or the mounting cover  43 . In detail, the hook  138  may include a vertical hook  138   b  protruding upward from the horizontal extension  142  and a horizontal hook  138   a  extending rearward from an end of the vertical hook  138   b . Thus, an entirety of the hook  138  may be formed in a hook shape. Further, one side of the inner casing  21  or the mounting cover  43  may be inserted and fastened into a space defined between the vertical hook  138   b  and the horizontal hook  138   a  to be locked to each other. 
     In one example, the hook  138  may protrude from an outer face of the vertical extension  140 . That is, a side end of the hook  138  may be coupled to and integrally formed with the vertical extension  140 . Thus, the hook  138  may satisfy a strength necessary to support the ice maker  100 . Further, the hook  138  will not break during attachment and detachment process of the ice maker  100 . 
     Further, an extended end of the horizontal hook  138   a  may be formed with an inclined portion  138   d  inclined upward, so that the hook  138  may be guided to a restraint position more easily when the ice maker  100  is mounted. Further, at least one protrusion  138   c  may be formed on a top face of the horizontal hook  138   a . The protrusion  138   c  may be in contact with the inner casing  21  or the mounting cover  43 , and therefore, vertical movement of the ice maker  100  may be prevented and the ice maker  100  may be more firmly mounted. 
     In one example, a threaded portion  142   a  may be formed at each of both front ends of the horizontal extension  142 . The threaded portion  142   a  may protrude downward, and may be coupled with the inner casing  21  or the mounting cover  43  by the screw for fixing the upper casing  120 . 
     Therefore, for the installation of the ice maker  100 , after placing the module-shaped ice maker  100  inside the freezing compartment  4 , the hook  138  is fastened to the inner casing  21  or the mounting cover  43 , and then the ice maker  100  is pressed upward. In this connection, a coupling hook  140   a  on the vertical extension  140  may be coupled with the mounting cover  43 , so that the ice maker  100  may be in an additional provisionally-fixed state. In this state, the screw may be fastened to the threaded portion  142   a , so that the front end of the upper casing  120  may be coupled to the inner casing  21  or mounting cover  43 , thereby completing the installation of the ice maker  100 . 
     In other words, the ice maker  100  may be mounted by fastening the rear end of the ice maker  100  and fixing the front end thereof with the screw without any complicated structure or component for mounting the ice maker  100 . The ice maker  100  may be easily detached in a reverse order. 
     In one example, an edge rib  120   d  may be formed along a perimeter of the horizontal extension  142 . The edge rib  120   d  may protrude vertically upward from the horizontal extension  142 , and may be formed along ends except for the rear end of the horizontal extension  142 . 
     When the ice maker  100  is mounted, the edge rib  120   d  may be brought into close contact with the outer face of the inner casing  21  or the mounting cover  43 , or may allow the ice maker  100  to be mounted horizontally with the ground on which the refrigerator  1  is installed. 
     To this end, a vertical level of the edge rib  120   d  may decrease from a front end thereof to a rear end thereof. In detail, a portion of the edge rib  120   d  formed along the front end of the horizontal extension  142  may be formed to have a highest vertical level and have a uniform vertical level. Further, a portion of the edge rib  120   d , which is formed along each of both sides of the horizontal extension  142 , may have a highest vertical level at a front end thereof, and a vertical level thereof may decrease rearwardly. 
     The vertical level of the front end, which has the highest vertical level in the edge rib  120   d , may be approximately 3 to 5 mm. Thus, as shown in  FIG.  6   , the horizontal extension  142 , which forms the top face of the ice maker  100 , may be disposed to have an inclination of approximately 7 to 8° downwards relative to the outer face of the inner casing  21  or the mounting cover  43 . 
     With such arrangement, even when the cabinet  2  is placed at an angle, the water level of the water supplied into the ice maker  100  may be horizontal, and the same amount of water may be received in the plurality of ice chambers  111 , so that the spherical ice cubes having the same size may be made. 
     In one example, the vertical extension  140  may be formed inward of the horizontal extension  142  and may extend vertically upward along the perimeter of the upper plate  121 . The vertical extension  140  may include at least one coupling hook  140   a . The upper casing  120  may be hooked to the mounting cover  43  by the coupling hook  140   a . Further, the water supply  190  may be coupled to the vertical extension  140 . 
     The upper casing  120  may further include a side wall  143 . The side wall  143  may extend downward from the horizontal extension  142 . The side wall  143  may be disposed to surround at least a portion of the perimeter of the lower assembly  200 . In other words, the side wall  143  prevents the lower assembly  200  from being exposed to the outside. 
     The side wall  143  may include a first side wall  143   a  in which a cold-air hole  134  is defined, and a second side wall  143   b  facing away from the first side wall  143   a . When the ice maker  100  is mounted in the freezing compartment  4 , the first side wall  143   a  may face a rear wall or one of both sidewalls of the freezing compartment  4 . 
     The lower assembly  200  may be located between the first side wall  143   a  and the second side wall  143   b . Further, since the ice-full state detection lever  700  rotates, an interference-prevention groove  148  may be defined in the side wall  143  such that interference is prevented in the rotation operation of the ice-full state detection lever  700 . 
     The through-openings  139   b  and  139   c  may include the first through-opening  139   b  positioned adjacent to the first side wall  143   a  and the second through-opening  139   c  positioned adjacent to the second side wall  143   b . Further, the tray opening  123  may be defined between the through-openings  139   b  and  139   c.    
     The cold-air hole  134  in the first side wall  143   a  may extend in the horizontal direction. The cold-air hole  134  may be defined in a corresponding size such that the front end of the cold-air duct  44  may be inserted therein. Therefore, an entirety of the cold-air supplied through the cold-air duct  44  may flow into the upper casing  120  through the cold-air hole  134 . 
     The cold-air guide  145  may be formed between both ends of the cold-air hole  134 , and the cold-air flowing into the cold-air hole  134  may be guided toward the tray opening  123  by the cold-air guide  145 . Further, a portion of the upper tray  150  exposed through the tray opening  123  may be exposed to the cold-air and directly cooled. 
     In one example, in the ice-full state detection lever  700 , the first inserted portion  740  is connected to the driver  180  and the second inserted portion  750  is coupled to the first side wall  143  a. 
     The driver  180  is coupled to the second side wall  143   a . In the ice-removal process, the lower assembly  200  is pivoted by the driver  180 , and the lower tray  250  is pressed by the lower ejector  400 . In this connection, relative movement between the driver  180  and the lower assembly  200  may occur in the process in which the lower tray  250  is pressed by the lower ejector  400 . 
     A pressing force of the lower ejector  400  applied on the lower tray  250  may be transmitted to an entirety of the lower assembly  200  or to the driver  180 . In one example, a torsional force is applied on the driver  180 . The force acting on the driver  180  then acts on the second side wall  134   b  too. When the second side wall  143   b  is deformed by the force acting on the second side wall  143   b , a relative position between the driver  180  and the connector  350  installed on the second side wall  143   b  may change. In this case, there is a possibility that the shaft of the driver  180  and the connector  350  are separated. 
     Therefore, a structure for minimizing the deformation of the second side wall  134   b  may be further provided on the upper casing  120 . In one example, the upper casing  120  may further include at least one first rib  148   a  connecting the upper plate  121  and the vertical extension  140  with each other, and a plurality of first ribs  148   a  and  148   b  may be spaced apart from each other. 
     An electrical-wire guide  148   c  for guiding the electrical-wire connected to the upper heater  148  or the lower heater  296  may be disposed between two adjacent first ribs  148   a  and  148   b  among the plurality of first ribs  148   a  and  148   b.    
     The upper plate  121  may include at least two portions in a stepped form. In one example, the upper plate  121  may include a first plate portion  121   a  and a second plate portion  121   b  positioned higher than the first plate portion  121   a.    
     In this case, the tray opening  123  may be defined in first plate portion  121   a.    
     The first plate portion  121   a  and the second plate portion  121   b  may be connected with each other by a connection wall  121   c . The upper plate  121  may further include at least one second rib  148   d  connecting the first plate portion  121   a , the second plate portion  121   b , and the connection wall  121   a  with each other. 
     The upper plate  121  may further include the electrical-wire guide hook  147  that guides the electrical wire to be connected with the upper heater  148  or lower heater  296 . In one example, the electrical-wire guide hook  147  may be provided in an elastically deformable form on the first plate portion  121   a.    
     Hereinafter, a cold-air guide structure of the upper casing  120  will be described in detail with reference to the accompanying drawings. 
       FIG.  15    is a partial plan view of an ice maker viewed from above. Further,  FIG.  16    is an enlarged view of a portion A of  FIG.  15   . Further,  FIG.  17    shows flow of cold-air on a top face of an ice maker. Further,  FIG.  18    is a perspective view of  FIG.  16    taken along a line  18 - 18 ′. 
     As shown in  FIGS.  15  and  18   , the cold-air hole  134  is not positioned in line with the ice chamber  111  and the tray opening  123 . Thus, the cold-air guide  145  may be formed to guide the cold-air flowed from the cold-air hole  134  toward the ice chamber  111  and the tray opening  123 . 
     When there is no cold-air guide on the upper casing  120 , the cold-air flowed through the cold-air hole  134  may not pass through the ice chamber  111  and the tray opening  123  or pass through only small portions thereof, which may reduce the cooling efficiency. 
     However, in the present embodiment, the cold-air introduced through the cold-air hole  134  may be led to sequentially pass upward of the ice chamber  111  and then through the tray opening  123  by the cold-air guide  145 . Thus, effective ice-making may be achieved in the ice chamber  111 , and ice-making speeds in the plurality of ice chambers  111  may be the same as or similar to each other. 
     The cold-air guide  145  may include a horizontal guide  145   a  and a plurality of vertical guides  145   b  and  145   c  for guiding the cold-air passed through the cold-air hole  134 . 
     The horizontal guide  145   a  may guide the cold-air to upward of the upper plate  121  in which the tray opening  123  is defined, at a position at or below the lowest point of the cold-air hole  134 . Further, the horizontal guide  145   a  may connect the first side wall  143   a  and the upper plate  121  with each other. The horizontal guide  145   a  may substantially form a portion of the bottom face of the upper plate  121 . 
     The plurality of vertical guides  145   b  and  145   c  may be arranged to intersect or to be perpendicular to the horizontal guide  145   a . The plurality of vertical guides  145   b  and  145   c  may include a first vertical guide  145   b  and a second vertical guide  145   c  spaced apart from the first vertical guide  145   b.    
     Further, an end of each of the first vertical guide  145   b  and the second vertical guide  145   c  may extend toward an ice chamber  111  on one side closest to the cold-air hole  134  among the plurality of ice chambers  111 . 
     The plurality of ice chambers  111  may include a first ice chamber  111   a , a second ice chamber  111   b , and a third ice chamber  111   c  that are sequentially arranged in a direction to be farther away from the cold-air hole  134 . That is, the first ice chamber  111   a  may be located closest to the cold-air hole  134  and the third ice chamber  111   c  may be located farthest from the cold-air hole  134 . The number of the ice chambers  111  may be three or more, and when the number of the ice chambers  111  is three or more, the number is not limited. 
     The first vertical guide  145   b  may extend from one end of the cold-air hole  134  to ends of the first ice chamber  111   a  and second ice chamber  111   b . In this connection, the first vertical guide  145   b  may have a predetermined curvature or a bent shape, so that the cold-air flowed from the cold-air hole  134  may be directed to the first ice chamber  111   a.    
     Further, the extended end of the first vertical guide  145   b  may be bent toward the second ice chamber  111   b . Thus, a portion of the cold-air discharged by the first vertical guide  145   b  may be directed toward the second ice chamber  111   b  after passing the end of the first ice chamber  111   a.    
     Further, the first vertical guide  145   b  may be formed not to extend to the second ice chamber  111   b  and formed in a bent or rounded shape, so that interference with electrical-wires provided on the upper plate  121  may not occur. 
     The second vertical guide  145   c  may extend toward the first ice chamber  111   a  from the other end of the cold-air hole  134 , which is facing away from the end where the first vertical guide  145   b  extends. 
     The second vertical guide  145   c  may be spaced apart from the extended end of the first vertical guide  145   b , and the first ice chamber  111   a  may be positioned between the ends of the first vertical guide  145   b  and the second vertical guide  145   c , so that the discharged cold-air may be directed toward the first ice chamber  111   a  by the cold-air guide  145 . 
     In one example, the second vertical guide  145   c  forms a portion of a perimeter of the first through-opening  139   b . This prevents the cold-air flowing along the cold-air guide  145  from entering the first through-opening  139   b  directly. 
     The cold-air guided by the cold-air guide  145  may be directed towards the first ice chamber  111   a . Further, the discharged cold-air may pass the plurality of ice chambers  111  sequentially, and finally, pass through the second through-opening  139   c  defined next to the third ice chamber  111   c.    
     Thus, as shown in  FIG.  17   , the cold-air passed through the cold-air hole  134  may be concentrated above the upper plate  121  by the cold-air guide  145 . Further, the cold-air that passed the upper plate  121  passes through the first and second through-openings  139   b  and  139   c.    
     Further, the supplied cold-air may be supplied to pass the plurality of ice chambers  111  sequentially along a direction of arrangement of the plurality of ice chambers  111  by the cold-air guide  145 . Further, the cold-air may be evenly supplied to all of the ice chambers  111 , so that the ice-making may be performed more effectively. Further, the ice-making speeds in the plurality of ice chambers  111  may be uniform. 
     In one example, it may be seen that the supplied cold-air is concentrated in the first ice chamber  111   a  by the cold-air guide  145  due to the arrangement of the ice chambers  111  as shown in  FIG.  17   . Therefore, it will be apparent that an ice formation speed in the first ice chamber  111   a , where the cold-air is concentratedly supplied, will be high in an early state of the ice-making. 
     In detail, the ice inside the ice chamber  111  may be made in an indirect cooling scheme. In particular, the supply of the cold-air is concentrated on the upper tray  150  side, and the lower tray  250  is naturally cooled by the cold-air in the refrigerator. In particular, in the present embodiment, in order to make the transparent spherical ice, the lower tray  250  is periodically heated by the lower heater  296  disposed in the lower tray  250 , so that the ice formation starts from the top of the ice chamber  111  and gradually proceeds downward. Thus, bubbles generated during the ice formation inside the ice chamber  111  may be concentrated in a lower portion of the lower tray  250 , so that ice transparent except for a bottom thereof where the bubbles are concentrated may be made. 
     Due to the nature of such cooling scheme, the ice formation occurs first in the upper tray  150 . The cold-air is concentrated in the first ice chamber  111   a , so that the ice formation may occur quickly in the first ice chamber  111   a . Further, due to the sequential flow of the cold-air, the ice formation begins sequentially in upper portions of the second ice chamber  111   b  and the third ice chamber  111   c.    
     Water expands in a process of being phase-changed into ice. When an ice making speed is high in the first ice chamber  111   a , an expansion force of the water is applied to the second ice chamber  111   b  and the third ice chamber  111   c . Then, the water in the first ice chamber  111   a  passes between the upper tray  150  and the lower tray  250  and flows toward the second ice chamber  111   b , and then the water in the second ice chamber  111   b  may sequentially flows toward the third ice chamber  111   c . As a result, water of an amount greater than the set amount may be supplied into the third ice chamber  111   c . Thus, ice made in the third ice chamber  111   c  may not have a relatively complete spherical shape, and may have a size different from that of ice cubes made in other ice chambers  111   a  and  111   b.    
     In order to prevent such a problem, the ice formation in the first ice chamber  111   a  should be prevented from being performed relatively faster, and preferably, the ice formation speed should be uniform in the ice chambers  111 . Further, the ice formation may occur in the second ice chamber  111   b  first rather than in the first ice chamber  111   a  to prevent water from concentrating into one ice chamber  111 . 
     To this end, a shield  125  may be formed in the tray opening  123  corresponding to the first ice chamber  111   a , and may minimize an area of exposure of the upper tray  150  corresponding to the first ice chamber  111   a.    
     In detail, the shield  125  may be formed in the cavity  122  corresponding to the first ice chamber  111   a , and a bottom of the cavity  122 , which defines the tray opening  123 , may extend toward a center portion thereof to form the shield  125 . That is, a portion of the tray opening  123  corresponding to the first ice chamber  111   a  has an area which is significantly small, and portions of the tray opening  123  respectively corresponding to the remaining second ice chamber  111   b  and third ice chamber  111   c  have larger areas. 
     Thus, as in a state in which the upper tray  150  is coupled to the upper casing  120  shown in  FIG.  15   , the top face of the upper tray  150  where the first ice chamber  111   a  is formed may be further shielded by the shield  125 . 
     The shield  125  may be rounded or inclined in a shape corresponding to an upper portion of an outer face of a portion corresponding to the first ice chamber  111   a  of the upper tray  150 . The shield  125  may extend centerward from the bottom of the cavity  122 , and may extend upward in a rounded or inclined manner. Further, an extended end of the shield  125  may define a shield opening  125   a . The shield opening  125   a  may have a size to be correspond to the ejector-receiving opening  154  in communication with the first ice chamber  111   a . Accordingly, in a state in which the upper casing  120  and the upper tray  150  are coupled with each other, only the ejector-receiving opening  154  may be exposed through the portion of the tray opening  123  corresponding to the first ice chamber  111   a.    
     Due to such structure, even when the cold-air supplied to pass the upper plate  121  is concentratedly supplied into the first ice chamber  111   a  by the cold-air guide  145 , the shield  125  may reduce the cold-air transmission into the first ice chamber  111   a . In other words, an adiabatic effect by the shield  125  may reduce the transmission of the cold-air into the first ice chamber  111   a . As a result, the ice formation in the first ice chamber  111   a  may be delayed, and the ice formation may not proceed in the first ice chamber  111   a  faster than in other ice chambers  111   b  and  111   c.    
     Further, the shield opening  125   a  may have a radially recessed rib groove  125   c  defined therein. The rib groove  125   c  may receive a portion of the first connection rib  155   a  radially disposed in the ejector-receiving opening  154 . To this end, the rib groove  125   c  may be recessed from a circumference of the shield opening  125   a  at a position corresponding to the first connection rib  155   a . A portion of the top of the first connection rib  155   a  is accommodated in the rib groove  125   c , so that the top face of the upper tray  150  that is rounded may be effectively surrounded. 
     Further, the portion of the top of the first connection rib  155   a  is accommodated in the rib groove  125   c , so that the top of the upper tray  150  may remain in place without leaving the shield  125 . Further, the deformation of the upper tray  150  may be prevented and the upper tray  150  may be maintained in a fixed shape, so that the ice made in the first ice chamber  111   a  may be ensured to have the spherical shape always. 
     In one example, a shield cut  125   b  may be defined in one side of the shield  125 . The shield cut  125   b  may be defined by being cut at a position corresponding to the second connection rib  162  to be described below, and may be define to receive the second connection rib  162  therein. 
     The shield  125  may be cut in a direction toward the second ice chamber  111   b , and may shield the remaining portion except for a portion where the second connection rib  162  is formed and the ejector-receiving opening  154  in communication with the first ice chamber  111   a.    
     The shield  125  may not be completely in contact with the top face of the upper tray  150  and may be spaced from the top face of the upper tray  150  by a predetermined distance. Due to such structure, an air layer may be formed between the shield  125  and the upper tray  150 . Therefore, heat insulation between the first ice chamber  111   a  and the corresponding portion may be further improved. 
     In one example, the first through-opening  139   b  and the second through-opening  139   c  may be defined in both sides of the tray opening  123 . Unit guides  181  and  182  to be described below and the first link  356  moving vertically along the unit guides  181  and  182  may pass through the first through-opening  139   b  and the second through-opening  139   c.    
     In particular, a stopper in contact with each of the unit guides  181  and  182  may protrude upward from each of the first through-opening  139   b  and the second through-opening  139   c  to restrain a horizontal movement of each of the unit guides  181  and  182 . 
     In detail, a first stopper  139   ba  and a second stopper  189   bb  may protrude from the first through-opening  139   b . The first stopper  139   ba  and the second stopper  189   bb  may be separated from each other to support the first unit guide  181  from both sides. In this connection, the second stopper  189   bb  may be formed by bending the end of the second vertical guide  145   c.    
     Further, a third stopper  189   ca  and a fourth stopper  189   cb  may protrude from the second through-opening  139   c . The third stopper  189   ca  and fourth stopper  189   cb  may be spaced apart from each other to support the second unit guide  182  from both sides. 
     Because of such structure, the horizontal movement of the unit guides  181  and  182  may be prevented fundamentally. Therefore, the movement of the upper ejector  300  along the unit guides  181  and  182  may also be prevented. In the vertical movement, the upper ejector  300  may press the upper tray  150  to deform or detach the upper tray  150 , so that the upper ejector  300  should be vertically moved at a fixed position. Thus, the upper ejector  300  is not interfered with the upper tray  150  by the stopper during the vertical movement process. 
     In one example, the fourth stopper  189   cb  among the stoppers may have a height slightly smaller than that of the other stoppers  139   ba ,  139   bb , and  139   ca . This is to allow the cold-air flowing along the upper tray  150  to pass the fourth stopper  189   cb  and be discharged smoothly through the second through-opening  139   c.    
     Hereinafter, the upper tray  150  will be described in more detail with reference to the accompanying drawings. 
       FIG.  19    is a perspective view of an upper tray according to an embodiment of the present disclosure viewed from above. Further,  FIG.  20    is a perspective view of an upper tray viewed from below. Further,  FIG.  21    is a side view of an upper tray. 
     Referring to  FIGS.  19  to  21   , the upper tray  150  may be made of a flexible or soft material that may be returned to its original shape after being deformed by an external force. 
     In one example, the upper tray  150  may be made of a silicone material. When the upper tray  150  is made of the silicone material as in the present embodiment, in the ice-removal process, even when the upper tray  150  is deformed by the external force, the upper tray  150  returns to its original shape, so that the spherical ice may be made despite the repetitive ice generation. 
     Further, when the upper tray  150  is made of the silicone material, the upper tray  150  may be prevented from melting or being thermally deformed by heat provided from the upper heater  148  to be described later. 
     The upper tray  150  may include the upper tray body  151  forming the upper chamber  152  that is a portion of the ice chamber  111 . A plurality of upper chambers  152  may be sequentially formed on the upper tray body  151 . The plurality of upper chambers  152  may include a first upper chamber  152   a , a second upper chamber  152   b , and a third upper chamber  152   c , which may be sequentially arranged in series on the upper tray  151 . 
     The upper tray body  151  may include three chamber walls  153  that form three independent upper chambers  152   a ,  152   b , and  152   c , and the three chamber walls  153  may be integrally formed and connected to each other. 
     The upper chamber  152  may be formed in a hemispherical shape. That is, an upper portion of the spherical ice may be formed by the upper chamber  152 . 
     An ejector-receiving opening  154  through which the upper ejector  300  may enter or exit for the ice-removal may be defined in an upper portion of the upper tray body  151 . The ejector-receiving opening  154  may be defined in a top of each of the upper chambers  152 . Therefore, each upper ejector  300  may independently push the ice cubes in each of the ice chambers  111  to remove the ice cubes. In another example, the ejector-receiving opening  154  has a diameter sufficient for the upper ejector  300  to enter and exit, which allows the cold-air flowing along the upper plate  121  to enter and exit. 
     In one example, in order to minimize the deformation of the portion of the upper tray  150  near the ejector-receiving opening  154  in a process in which the upper ejector  300  is inserted through the ejector-receiving opening  154 , an opening-defining wall  155  may be formed on the upper tray  150 . The opening-defining wall  155  may be disposed along the circumference of the ejector-receiving opening  154 , and may extend upward from the upper tray body  151 . 
     The opening-defining wall  155  may be formed in a cylindrical shape. Thus, the upper ejector  300  may pass through an internal space of the opening-defining wall  155  and pass through the ejector-receiving opening  154 . 
     The opening-defining wall may act as a guide for movement of the upper ejector  300 , and at the same time, may define extra space to prevent the water contained in the ice chamber  111  from overflowing. Therefore, the internal space of the opening-defining wall  155 , that is, the space in which the ejector-receiving opening  154  is defined, may be referred to as a buffer. 
     Since the buffer is formed, even when the water of the amount equal to or greater than the predefined amount is flowed into the ice chamber  111 , the water will not overflow. When the water inside the ice chamber  111  overflows, ice cubes respectively contained in adjacent ice chambers  111  may be connected with each other, so that the ice may not be easily separated from the upper tray  150 . Further, when the water inside the ice chamber may overflow from the upper tray  150 , serious problems, such as induction of attachment of the ice cubes in the ice chambers may occur. 
     In the present embodiment, the buffer is formed by the opening-defining wall  155  to prevent the water inside the ice chamber  111  from overflowing. When a height of the opening-defining wall  155  becomes excessively large to form the buffer, the buffer may interfere with the movement of the cold-air of passing the upper plate  121  and inhibit smooth movement of the cold-air. On the contrary, when the height of the opening-defining wall  155  becomes excessively small, a role of the buffer may not be expected and it may be difficult to guide the movement of the upper ejector  300 . 
     In one example, a preferred height of the buffer may be a height corresponding to the horizontal extension  142  of the upper tray  150 . Further, a capacity of the buffer may be set based on an inflow amount of ice debris that may be attached along a circumference of the upper tray body  151 . Therefore, it is preferable that an internal volume of the buffer is defined to have a capacity of 2 to 4% of a volume of the ice chamber  111 . 
     When an inner diameter of the buffer is too large, the top of the completed ice may have an excessively wide flat shape, and thus, an image of the spherical ice may not be provided to the user. Therefore, the buffer should be formed to have a proper inner diameter. 
     The inner diameter of the buffer may be larger than a diameter of the upper ejector  300  to facilitate entry and exit of the upper ejector  300 , and may be determined to satisfy the water capacity and height of the buffer. 
     In one example, the first connection rib  155   a  for connecting the side of the opening-defining wall  155  and the top face of the upper tray body  151  with each other may be formed on the circumference of the opening-defining wall  155 . A plurality of the first connection ribs  155   a  may be formed at regular intervals along the circumference of the opening-defining wall  155 . Thus, the opening-defining wall  155  may be supported by the first connection rib  155   a  such that the opening-defining wall  155  is not deformed easily. Even when the upper ejector  300  is in contact with the opening-defining wall  155  in a process of being inserted into the ejector-receiving opening  154 , the opening-defining wall  155  may maintain its shape and position without being deformed. 
     The first connection rib  155   a  may be formed on each of all the first upper chamber  152   a  and second upper chamber  152   b  and third upper chamber  152   c.    
     In one example, two opening-defining walls  155  respectively corresponding to the second upper chamber  152   b  and the third upper chamber  152   c  may be connected with each other by a second connection rib  162 . The second connection rib  162  may connect the second upper chamber  152   b  and the third upper chamber  152   c  with each other to further prevent the deformation of the opening-defining wall  155 , and at the same time, to prevent deformation of top faces of the second upper chamber  152   b  and the third upper chamber  152   c.    
     In one example, the second connection rib  162  may also be disposed between the first upper chamber  152   a  and the second upper chamber  152   b  to connect the first upper chamber  152   a  and the second upper chamber  152   b  with each other, but the second connection rib  162  may be omitted since the second receiving space  161  in which the temperature sensor  500  is disposed is defined between the first upper chamber  152   a  and the second upper chamber  152   b.    
     The water-supply guide  156  may be formed on the opening-defining wall  155  corresponding to one of the three upper chambers  152   a ,  152   b , and  152   c.    
     Although not limited, the water-supply guide  156  may be formed on the opening-defining wall  155  corresponding to the second upper chamber  152   b . The water-supply guide  156  may be inclined upward from the opening-defining wall  155  in a direction farther away from the second upper chamber  152   b . Even when only one water-supply guide is formed on the upper chamber  152 , the upper tray  150  and the lower tray  250  may not be closed during the water-supply, so that water may be evenly filled in all the ice chambers  111 . 
     The upper tray  150  may further include a first receiving space  160 . The first receiving space  160  may accommodate the cavity  122  of the upper casing  120  therein. The cavity  122  includes a heater-mounted portion  124 , and the heater-mounted portion  124  includes the upper heater  148 , so that it may be understood that the upper heater  148  is accommodated in the first receiving space  160 . 
     The first receiving space  160  may be defined in a form surrounding the upper chambers  152   a ,  152   b , and  152   c . The first receiving space  160  may be defined as the top face of the upper tray body  151  is recessed downward. 
     The temperature sensor  500  may be accommodated in the second receiving space  161 , and the temperature sensor  500  may be in contact with an outer face of the upper tray body  151  while the temperature sensor  500  is mounted. 
     The chamber wall  153  of the upper tray body  151  may include a vertical wall  153   a  and a curved wall  153   b.    
     The curved wall  153   b  may be upwardly rounded in a direction farther away from the upper chamber  152 . In this connection, a curvature of the curved wall  153   b  may be the same as a curvature of a curved wall  260   b  of the lower tray  250  to be described below. Thus, when the lower tray  250  pivots, the upper tray  150  and the lower tray  250  do not interfere with each other. 
     The upper tray  150  may further include a horizontal extension  164  extending in a horizontal direction from a perimeter of the upper tray body  151 . The horizontal extension  164  may, for example, extend along a perimeter of a top edge of the upper tray body  151 . 
     The horizontal extension  164  may be in contact with the upper casing  120  and the upper support  170 . A bottom face  164   b  of the horizontal extension  164  may be in contact with the upper support  170 , and a top face  164   a  of the horizontal extension  164  may be in contact with the upper casing  120 . Thus, at least a portion of the horizontal extension  164  may be fixedly mounted between the upper casing  120  and the upper support  170 . 
     The horizontal extension  164  may include a plurality of upper protrusions  165  respectively inserted into the plurality of upper slots  131  and a plurality of upper protrusions  166  respectively inserted into the plurality of upper slots  132 . 
     The plurality of upper protrusions  165  and  166  may include a plurality of first upper protrusions  165  and a plurality of second upper protrusions  166  positioned opposite to the first upper protrusions  165  around the ejector-receiving opening  154 . 
     The first upper protrusion  165  may be formed in a shape corresponding to the first upper slot  131  to be inserted into the first upper slot  131 , and the second upper protrusion  166  may be formed in a shape corresponding to the second upper slot  132  to be inserted into the second upper slot  132 . Further, the first upper protrusion  165  and the second upper protrusion  166  may protrude from the top face  164   a  of the horizontal extension  164 . 
     The first upper protrusion  165  may be, for example, formed in a curved shape. Further, the second upper protrusion  166  may be, for example, formed in a curved shape. Further, the first upper protrusion  165  and the second upper protrusion  166  may be arranged to face away from each other around the ice chamber  111 , so that the perimeter of the ice chamber  111  may be maintained in a firmly coupled state, in particular. 
     The horizontal extension  164  may further include a plurality of lower protrusions  167  and a plurality of lower protrusions  168 . Each of the plurality of lower protrusions  167  and each of the plurality of lower protrusions  168  may be respectively inserted into lower slots  176  and  177  of the upper support  170  to be described later. 
     The plurality of lower protrusions  167  and  168  may include a first lower protrusion  167  and a second lower protrusion  168  positioned opposite to the first lower protrusion  167  around the upper chamber  152 . 
     The first lower protrusion  167  and the second lower protrusion  168  may protrude downward from the bottom face  164   b  of the horizontal extension  164 . The first lower protrusion  167  and the second lower protrusion  168  may be formed in the same shape as the first upper protrusion  165  and the second upper protrusion  166 , and may be formed to protrude in a direction opposite to a protruding direction of the first upper protrusion  165  and the second upper protrusion  166 . 
     Thus, because of the upper protrusions  165  and  166  and the lower protrusions  167  and  168 , not only the upper tray  150  is coupled between the upper casing  120  and the upper support, but also deformation of the ice chamber  111  or the horizontal extension  264  adjacent to the ice chamber  111  is prevented in the ice-making or ice-removal process. 
     The horizontal extension  164  may have a through-hole  169  defined therein to be penetrated by a coupling boss of the upper support  170  to be described later. Some of a plurality of through-holes  169  may be located between two adjacent first upper protrusions  165  or two adjacent first lower protrusions  167 . Some of the remaining through-holes  169  may be located between two adjacent second lower protrusions  168  or may be defined to face a region between the two second lower protrusions  168 . 
     In one example, an upper rib  153   d  may be formed on the bottom face  153   c  of the upper tray body  151 . The upper rib  153   d  is for hermetic sealing between the upper tray  150  and the lower tray  250 , which may be formed along the perimeter of each of the ice chambers  111 . 
     In a structure in which the ice chamber  111  is formed by the coupling of the upper tray  150  and the lower tray  250 , even when the upper tray  150  and the lower tray  250  remain in close contact with each other at first, a gap is defined between the upper tray  150  and the lower tray  250  due to a volume expansion occurring in a process in which the water is phase-changed into the ice. When the ice formation occurs in a state in which the upper tray  150  and the lower tray  250  are separated from each other, a burr that protrudes in a shape of an ice strip is generated along a circumference of the completed spherical ice. Such burr generation causes a poor shape of the spherical ice itself. In particular, when the ice is connected to ice debris formed in a circumferential space between the upper tray  150  and the lower tray  250 , the shape of the spherical ice becomes worse. 
     In order to solve such problem, in the present embodiment, the upper rib  153   d  may be formed at the bottom of the upper tray  150 . The upper rib  153   d  may shield between the upper tray  150  and the lower tray  250  even when the volume expansion of the water due to the phase-change occurs. Thus the bur may be prevented from being formed along the circumference of the completed spherical ice. 
     In detail, the upper rib  153   d  may be formed along the perimeter of each of the upper chambers  152 , and may protrude downward in a thin rib shape. Therefore, in a situation where the upper tray  150  and the lower tray  250  are completely closed, deformation of the upper rib  153   d  will not interfere with the sealing of the upper tray  150  between the lower tray  250 . 
     Therefore, the upper rib  153   d  may not be formed excessively long. Further, it is preferable that the upper rib  153   d  is formed to have a height sufficient to cover the gap between the upper tray  150  and the lower tray  250 . In one example, the upper tray  150  and the lower tray  250  may be separated from each other by about 0.5 mm to 1 mm when the ice is formed, and correspondingly the upper rib  153   d  may be formed with a height h 1  of about 0.8 mm. 
     In one example, the lower tray  250  may be pivoted in a state in which a pivoting shaft thereof is positioned outward (rightward in  FIG.  21   ) of the curved wall  153   b . In such structure, when the lower tray  250  is closed by pivoting, a portion thereof close to the pivoting shaft is brought to be in contact with the upper tray  150  first, and then a portion thereof far away from the pivoting shaft is sequentially brought to be in contact with the upper tray  150  as the upper tray  150  and the lower tray  250  are compressed. 
     Thus, when the upper rib  153   d  is formed along an entirety of the perimeter of the bottom of the upper chamber  152 , interference of the upper rib  153   d  may occur at a position near the pivoting shaft, which may cause the upper tray  150  and the lower tray  250  not to be closed completely. In particular, there is a problem that the upper tray  150  and the lower tray  250  are not closed at a position far away from the pivoting shaft. 
     In order to prevent such problem, the upper rib  153   d  may be formed to be inclined along the perimeter of the upper chamber  152 . The upper rib  153   d  may be formed such that a height thereof increases toward the vertical wall  153   a  and decreases toward the curved wall  153   b . One end of the upper rib  153   d  close to the vertical wall  153   b  may have a maximum height h 1 , the other end of the upper rib  153   d  close to the curved wall  153   b  may have a minimum height, and the minimum height may be zero. 
     Further, the upper rib  153   d  may not be formed on the entirety of the upper chamber  152 , but may be formed on the remaining portion of the upper chamber  152  except for a portion thereof near the curved wall  153   b . In one example, as shown in  FIG.  21   , based on a length L of an entire width of the bottom of the upper tray  150 , the upper rib  153   d  may start to protrude from a position away from an end at which the curved wall  153   b  is formed by ⅕ length L 1  and extend to an end at which the vertical wall  153   b  is formed. Therefore, a width of the upper rib  153   d  may be ⅘ length L 2  based on the length L of the entire width of the bottom of the upper tray  150 . In one example, when the width of the bottom of the upper tray  150  is 50 mm, the upper rib  153   d  extends downwards from a position 10 mm away from the end of the curved wall  153   b , and may extend to the end adjacent to the vertical wall  153   a . In this connection, the width of the upper rib  153   d  may be 40 mm. 
     In another example, there may be some differences, but the point where the upper rib  153   d  starts to protrude may be a point away from the curved wall  153   b  such that the interference may be minimized when the lower tray  250  is closed, and at the same time, the gap between the upper tray  150  and the lower tray  250  may be covered. 
     Further, the height of the upper rib  153   d  may increase from the curved wall  153   b  side to the vertical wall  153   a  side. Thus, when the lower tray  250  is opened by the freezing, the gap between the upper tray  150  and the lower tray  250  having varying height may be effectively covered. 
     Hereinafter, the upper support  170  will be described in more detail with reference to the accompanying drawings. 
       FIG.  22    is a perspective view of an upper support according to an embodiment of the present disclosure viewed from above. Further,  FIG.  23    is a perspective view of an upper support viewed from below. Further,  FIG.  24    is a cross-sectional view showing a coupling structure of an upper assembly according to an embodiment of the present disclosure. 
     Referring to  FIGS.  22  to  24   , the upper support  170  may include a plate shaped support plate  171  that supports the upper tray  150  from below. Further, a top face of the support plate  171  may be in contact with the bottom face  164   b  of the horizontal extension  164  of the upper tray  150 . 
     The support plate  171  may have a plate opening  172  defined therein to be penetrated by the upper tray body  151 . A side wall  174 , which is bent upward, may be formed along an edge of the support plate  171 . The side wall  174  may be in contact with a perimeter of the side of the horizontal extension  164  to restrain the upper tray  150 . 
     The support plate  171  may include a plurality of lower slots  176  and a plurality of lower slots  177 . The plurality of lower slots  176  and the plurality of lower slots  177  may include a plurality of first lower slots  176  into which the first lower protrusions  167  are inserted respectively and a plurality of second lower slots  177  into which the second lower protrusions  168  are inserted respectively. 
     The plurality of first lower slots  176  and the plurality of second lower slots  177  may be formed to be inserted into each other in a shape corresponding to a position corresponding to the first lower protrusion  167  and the second lower protrusion  168 , respectively. 
     The first lower slot  176  may be defined to have a shape corresponding to the first lower protrusion  167  at a position corresponding to the first lower protrusion  167  such that the first lower protrusion  167  may be inserted into the first lower slot  176 . Further, the second lower slot  177  may be defined to have a shape corresponding to the second lower protrusion  168  at a position corresponding to the second lower protrusion  168  such that the second lower protrusion  168  may be inserted into the second lower slot  177 . 
     The support plate  171  may further include a plurality of coupling bosses  175 . The plurality of coupling bosses  175  may protrude upward from the top face of the support plate  171 . Each coupling boss  175  may be inserted into the sleeve  133  of the upper casing  120  by passing through the through-hole  169  of the horizontal extension  164 . 
     In a state in which the coupling boss  175  is inserted into the sleeve  133 , a top face of the coupling boss  175  may be located at the same vertical level or below the top face of the sleeve  133 . The fastener such as a bolt may be fastened to the coupling boss  175 , so that the assembly of the upper assembly  110  may be completed, and the upper casing  120 , the upper tray  150 , and upper support  170  may be rigidly coupled to each other. 
     The upper support  170  may further include a plurality of unit guides  181  and  182  for guiding the connector  350  connected to the upper ejector  300 . The plurality of unit guides  181  and  182  may be respectively formed at both ends of the upper plate  170  to be spaced apart each other, and may be respectively formed at positions facing away from each other. 
     The unit guides  181  and  182  may respectively extend upwards from the both ends of the support plate  171 . Further, a guide slot  183  extending in the vertical direction may be defined in each of the unit guides  181  and  182 . 
     In a state in which each of both ends of the ejector body  310  of the upper ejector  300  penetrates the guide slot  183 , the connector  350  is connected to the ejector body  310 . Thus, in the pivoting process of the lower assembly  200 , when the pivoting force is transmitted to the ejector body  310  by the connector  350 , the ejector body  310  may vertically move along the guide slot  183 . 
     In one example, a plate electrical-wire guide  178  extending downward may be formed at one side of the support plate  171 . The plate electrical-wire guide  178  is for guiding the electrical wire connected to the lower heater  296 , which may be formed in a hook shape extending downward. The plate electrical-wire guide  178  is formed on an edge of the support plate  171  to minimize interference of the electrical-wire with other components. 
     Further, an electrical-wire opening  178   a  may be defined in the support plate  171  to correspond to the plate electrical-wire guide  178 . The electrical-wire opening  178   a  may direct the electrical-wire guided by the plate electrical-wire guide  178  to pass through the support plate  171  and toward the upper casing  120 . 
     In one example, as shown in  FIGS.  13  and  24   , the heater-mounted portion  124  may be formed in the upper casing  120 . The heater-mounted portion  124  may be formed on the bottom of the cavity  122  defined along the tray opening  123 , and may include a heater-receiving groove  124   a  defined therein for accommodating the upper heater  148  therein. 
     The upper heater  148  may be a wire type heater. Thus, the upper heater  148  may be inserted into the heater-receiving groove  124   a , and may be disposed along a perimeter of the tray opening  123  of the curved shape. The upper heater  148  is brought to be in contact with the upper tray  150  by the assembling the upper assembly  110 , so that the heat transfer to the upper tray  150  may be achieved. 
     Further, the upper heater  148  may be a DC powered DC heater. When the upper heater  148  is operated for the ice-removal, heat from the upper heater  148  may be transferred to the upper tray  150 , so that the ice may be separated from a surface (inner face) of the upper tray  150 . 
     When the upper tray  150  is made of the metal material and as the heat from the upper heater  148  is strong, after the upper heater  148  is turned off, a portion of the ice heated by the upper heater  148  adheres again to the surface of the upper tray  150 , so that the ice becomes opaque. 
     In other words, an opaque strip of a shape corresponding to the upper heater is formed along a circumference of the ice. 
     However, in the present embodiment, the DC heater having a low output is used, and the upper tray  150  is made of silicone, so that an amount of the heat transferred to the upper tray  150  is reduced and a thermal conductivity of the upper tray  150  itself is lowered. 
     Therefore, since the heat is not concentrated in a local portion of the ice, and a small amount of the heat is gradually applied to the ice, the formation of the opaque strip along the circumference of the ice may be prevented while the ice is effectively separated from the upper tray  150 . 
     The upper heater  148  may be disposed to surround the perimeter of each of the plurality of upper chambers  152  such that the heat from the upper heater  148  may be evenly transferred to the plurality of upper chambers  152  of the upper tray  150 . 
     In one example, as shown in  FIG.  24   , in a state in which the upper heater  148  is coupled to the heater-mounted portion  124  of the upper casing  120 , the upper assembly may be assembled by coupling the upper casing  120 , the upper tray  150 , and upper support  170  with each other. 
     In this connection, the first upper protrusion  165  of the upper tray  150  may be inserted into the first upper slot  131  of the upper casing  120 , and the second upper protrusion  166  of the upper tray  150  may be inserted into the second upper slot  132  of the upper casing  120 . 
     Further, the first lower protrusion  167  of the upper tray  150  may be inserted into the first lower slot  176  of the upper support  170 , and the second lower protrusion  168  of the upper tray may be inserted into the second lower slot  177  of the upper support  170 . 
     Then, the coupling boss  175  of the upper support  170  passes through the through-hole  169  of the upper tray  150  and is received within the sleeve  133  of the upper casing  120 . In this state, the fastener such as the bolt may be fastened to the coupling boss  175  from upward of the coupling boss  175 . 
     When the upper assembly  110  is assembled, the heater-mounted portion  124  in combination with the upper heater  148  is received in the first receiving space  160  of the upper tray  150 . In a state in which the heater-mounted portion  124  is received in the first receiving space  160 , the upper heater  148  is in contact with the bottom face  160   a  of the first receiving space  160 . 
     As in the present embodiment, when the upper heater  148  is accommodated in the heater-mounted portion  124  in the recessed form and in contact with the upper tray body  151 , the transferring of the heat from the upper heater  148  to other components other than the upper tray body  151  may be minimized. 
     In one example, the present disclosure may also include another example of another ice maker. In another embodiment of the present disclosure, there are differences only in a structure of the upper tray  150  and a structure of the shield  125  of the upper casing  120 , and other components will be identical. The same component will not be described in detail and will be described using the same reference numerals. 
     Hereinafter, structures of the upper tray and the shield according to another embodiment of the present disclosure will be described with reference to the drawings. 
       FIG.  25    is a perspective view of an upper tray according to another embodiment of the present disclosure viewed from above. Further,  FIG.  26    is a cross-sectional view of  FIG.  25    taken along a line  26 - 26 ′. Further,  FIG.  27    is a cross-sectional view of  FIG.  25    taken along a line  27 - 27 ′. Further,  FIG.  28    is a partially-cut perspective view showing a structure of a shield of an upper casing according to another embodiment of the present disclosure. 
     As shown in  FIGS.  25  to  28   , an upper tray  150 ′ according to another embodiment of the present disclosure differs only in structures of the opening-defining wall  155  and the top face of the upper chamber  152  connected with the opening-defining wall  155 , but other components thereof are the same as in the above-described embodiment. 
     The upper tray  150 ′ includes the horizontal extension  142  formed thereon. Further, the horizontal extension  142  may include the first upper protrusion  165 , the second upper protrusion  166 , the first lower protrusion  167 , and the second lower protrusion  168  formed thereon. Further, the through-hole  169  may be defined in the horizontal extension  142 . 
     Further, the upper chamber  152  may be formed in the upper tray body  151  extending downward from the horizontal extension  142 . The upper chamber  152  may include the first upper chamber  152   a , the second upper chamber  152   b , and the third upper chamber  152   c  arranged successively from a side close to the cold-air guide  145 . 
     The opening-defining wall  155  that defines the ejector-receiving opening  154  may be formed on each of the upper chambers  152 . Further, the water-supply guide  156  may be formed on the opening-defining wall  155  of the second upper chamber  152   b . In one example, a plurality of ribs that connect the outer face of the opening-defining wall  155  and the top face of the upper chamber  152  may be arranged on the opening-defining wall  155  of each the upper chambers  152 . 
     In detail, the plurality of radially arranged first connection ribs  155   a  may be formed on the first upper chamber  152   a  and the second upper chamber  152   b . The first connection rib  155   a  may prevent the deformation of the opening-defining wall  155 . Further, the first upper chamber  152   a  and the second upper chamber  152   b  may be connected with each other by a second connection rib  162 , and the deformation of the first upper chamber  152   a , the second upper chamber  152   b , and the opening-defining wall  155  may be further prevented. 
     Further, the third upper chamber  152   c  may be spaced apart for mounting the temperature sensor  500 . Thus, a plurality of third connection ribs  155   c  may be formed to prevent deformation of the opening-defining wall  155  formed upward of the third upper chamber  152   c . The plurality of third connection ribs  155   c  may be formed in the same shape as the first connection rib  155   a , and may be arranged at an interval narrower than in the first upper chamber  152   a  or the second upper chamber  152   b . That is, the third upper chamber  152   c  will have more ribs than the other chambers  152   a  and  152   b . Thus, even when the third upper chamber  152   c  is placed separately, a shape the third upper chamber  152   c  may be maintained, and the third upper chamber  152   c  may be prevented from deforming easily. 
     In one example, a thermally-insulating portion  152   e  may be formed on the top face of the first upper chamber  152   a . The thermally-insulating portion  152   e  is for further blocking the cold-air passing through the upper tray  150 ′ and upper casing  120 , which further protrudes along the perimeter of the first upper chamber  152   a . The thermally-insulating portion  152   e  is a face exposed through the top face of the first upper chamber  152   a , that is, exposed upwardly of the upper tray  150 ′, which is formed along the perimeter of the bottom of the opening-defining wall  155 . 
     In detail, as shown in  FIGS.  26  and  27   , a thickness D 1  of the upper face of the first upper chamber  152   a  may be larger than a thickness D 2  of the upper faces of the second upper chamber  152   b  and of the third upper chamber  152   c  by the thermally-insulating portion  152   e.    
     When the thickness of the first upper chamber  152   a  is larger by the thermally-insulating portion  152   e , even in a state in which the supplied cold-air is concentrated on the first upper chamber  152   a  side by the cold-air guide  145 , the amount of the cold-air transferred to the first upper chamber  152   a  may be reduced. As a result, the thermally-insulating portion  152   e  may reduce the ice formation speed in the first upper chamber  152   a . Thus, the ice formation may occur first in the second upper chamber  152   b  or the ice formation may occur at a uniform speed in the upper chambers  152 . 
     In one example, the shield  126  that extends from the cavity  122  of the upper casing  120  may be formed upward of the first upper chamber  152   a . The shield  126  protrudes upward to cover the top face of the first upper chamber  152   a , and may be formed round or inclined. 
     A shield opening  126   a  is defined at a top of the shield  126 , and the shield opening  126   a  is in contact with the top of the ejector-receiving opening  154 . Therefore, when the upper tray  150 ′ is viewed from above, the remaining portion of the first upper chamber  152   a  except for the ejector-receiving opening  154  is covered by the shield  126 . That is, a region of the thermally-insulating portion  152   e  is covered by the shield  126 . 
     Further, a rib groove  126   c  to be inserted into the top of the first connection rib  155   a  may be defined along a circumference of the shield opening  126   a , so that positions of the top of the first upper chamber  152   a  and the opening-defining wall  155  may be maintained in place. 
     With such structure, the first upper chamber  152   a  may be thermally-insulated further, and the ice formation speed in the first upper chamber  152   a  may be reduced despite the cold-air concentratedly supplied by the cold-air guide  145 . 
     In one example, a cut  126   e  may be defined in the shield  126  corresponding to the second connection rib  162 . The cut  126   e  is formed by cutting a portion of the shield  125 , which may be opened to allow the second connection rib  162  to pass therethrough completely. 
     When the cut  126   e  is too narrow, in a process in which the upper tray  150 ′ is deformed during the ice-removal process by the upper ejector  300 , the second connection rib  162  may be deviated from the cut  126   e  and jammed. In this case, the second connection rib  162  is unable to return to its original position after the ice-removal, causing defects during the ice-making. On the contrary, when the cut  126   e  is too wide, the thermal insulation effect may be significantly reduced due to the inflow of the cold-air. 
     Thus, in the present embodiment, a width of the cut  126   e  may decrease upwardly. That is, both ends  126   b  of the cut  126   e  may be formed in an inclined or rounded shape, so that a width of a bottom of the cut  126   e  may be the widest and a width of a top of the cut  126   e  may be the narrowest. Further, the width of the top of the cut  126   e  may correspond to or be somewhat larger than the thickness of the second connection rib  162 . 
     Therefore, when the upper tray  150 ′ is deformed and then restored during the ice-removal by the upper ejector  300 , the second connection rib  162  may be easily inserted into the cut  126   e  and moved along both ends of the cut  126   e , so that the upper tray  150 ′ may be restored at a correct position. 
     In one example, when the opening of the bottom of the cut  126   e  becomes large, the cold-air may be introduced through the bottom of the cut  126   e . In order to prevent this, fourth connection ribs  155   b  may be formed along the perimeter of the first upper chamber  152   a.    
     Like the first connection rib  155   a , the fourth connection rib  155   b  may be formed to connect the outer face of the opening-defining wall  155  and the upper face of the first upper chamber  152   a  with each other, and an outer end thereof may be inclined. Further, a height of the fourth connection rib  155   b  may be smaller than that of the first connection rib  155   a , so that the fourth connection rib  155   b  may be in contact with the bottom face of the shield without interfering with the top of the shield  126 . 
     The fourth connection ribs  155   b  may be respectively located at both left and right sides around the second connection rib  162 . Further, the fourth connection ribs  155   b  may be respectively located at positions corresponding to the both ends of the cut  126   e  or slightly outward of the both ends of the cut  126   e . The fourth connection ribs  155   b  may be in close contact with the inner face of the shield  126 . Thus, a space between the shield  126  and the top face of the first upper chamber  152   a  may be shielded to prevent the cold-air from entering through the cut  126   e.    
     The shield  126  and the top face of the first upper chamber  152   a  may be somewhat spaced apart from each other, and an air layer may be formed therebetween. The inflow of the cold-air from the air layer may be blocked by the fourth connection rib  155   b . Therefore, the top face of the first upper chamber  152   a  may be further thermally insulated to further reduce the ice formation speed in the first upper chamber  152   a.    
     Hereinafter, the lower assembly  200  will be described in more detail with reference to the accompanying drawings. 
       FIG.  29    is a perspective view of a lower assembly according to an embodiment of the present disclosure. Further,  FIG.  30    is an exploded perspective view of a lower assembly viewed from above. Further,  FIG.  31    is an exploded perspective view of a lower assembly viewed from below. 
     As shown in  FIGS.  29  to  31   , the lower assembly  200  may include a lower tray  250 , a lower support  270  and a lower casing  210 . 
     The lower casing  210  may surround a portion of a perimeter of the lower tray  250 , and the lower support  270  may support the lower tray  250 . Further, the connector  350  may be coupled to both sides of the lower support  270 . 
     The lower casing  210  may include a lower plate  211  for fixing the lower tray  250 . A portion of the lower tray  250  may be fixed in contact with a bottom face of the lower plate  211 . The lower plate  211  may be provided with an opening  212  defined therein through which a portion of the lower tray  250  penetrates. 
     In one example, when the lower tray  250  is fixed to the lower plate  211  in a state of being positioned below the lower plate  211 , a portion of the lower tray  250  may protrude upward of the lower plate  211  through the opening  212 . 
     The lower casing  210  may further include a side wall  214  surrounding the the portion of the lower tray  250  passed through the lower plate  211 . The side wall  214  may include a vertical portion  214   a  and a curved portion  215 . 
     The vertical portion  214   a  is a wall extending vertically upward from the lower plate  211 . The curved portion  215  is a wall that is rounded upwardly in a direction farther away from the opening  212  upwards from the lower plate  211 . 
     The vertical portion  214   a  may include a first coupling slit  214   b  defined therein to be coupled with the lower tray  250 . The first coupling slit  214   b  may be defined as a top of the vertical portion  214   a  is recessed downward. 
     The curved portion  215  may include a second coupling slit  215   a  defined therein to be coupled with the lower tray  250 . The second coupling slit  215   a  may be defined as a top of the curved portion  215  is recessed downward. The second coupling slit  215   a  may restrain a lower portion of the second coupling protrusion  261  protruding from the lower tray  250 . 
     Further, a protruding confiner  213  protruding upward may be formed on a rear face of the curved portion  215 . The protruding confiner  213  may be formed at a position corresponding to the second coupling slit  215   a , and may protrude outward from a face in which the second coupling slit  215   a  is defined to restrain an upper portion of the second coupling protrusion  261 . 
     That is, both top and bottom of the second coupling protrusion  261  may be restrained by the second coupling slit  215   a  and the protruding confiner  213 , respectively. Thus, the lower tray  250  may be firmly fixed to the lower casing  210 . 
     Structure of the second coupling protrusion  261 , the second coupling slit  215   a , and the protruding confiner  213  will be described in more detail below. 
     In one example, the lower casing  210  may further include a first coupling boss  216  and a second coupling boss  217 . The first coupling boss  216  may protrude downward from the bottom face of the lower plate  211 . In one example, a plurality of first coupling bosses  216  may protrude downward from the lower plate  211 . 
     The second coupling boss  217  may protrude downward from the bottom face of the lower plate  211 . In one example, a plurality of second coupling bosses  217  may protrude from the lower plate  211 . 
     In the present embodiment, a length of the first coupling boss  216  and a length of the second coupling boss  217  may be different. In one example, the length of the second coupling boss  217  may be larger than the length of the first coupling boss  216 . 
     A first fastener may be fastened to the first coupling boss  216  from upward of the first coupling boss  216 . On the other hand, a second fastener may be fastened to the second coupling boss  217  from below of the second coupling boss  217 . 
     A groove  215   b  for a movement of the fastener may be defined in the curved portion  215  such that the first fastener does not interfere with the curved portion  215  in a process in which the first fastener is fastened to the first coupling boss  216 . 
     The lower casing  210  may further include a slot  218  for coupling with the lower tray  250  defined therein. A portion of the lower tray  250  may be inserted into the slot  218 . The slot  218  may be located adjacent to the vertical portion  214   a.    
     The lower casing  210  may further include a receiving groove  218   a  defined therein for insertion of a portion of the lower tray  250 . The receiving groove  218   a  may be defined as a portion of the lower plate  211  is recessed toward the curved portion  215 . 
     The lower casing  210  may further include an extension wall  219  in contact with a portion of a perimeter of a side of the lower plate  212  in a state in which the lower casing  210  is coupled with the lower tray  250 . 
     In one example, the lower tray  250  may be made of a flexible material or a flexible material such that the lower tray  250  may be deformed by an external force and then returned to its original form. 
     In one example, the lower tray  250  may be made of a silicone material. When the lower tray  250  is made of the silicone material as in the present embodiment, even when the external force is applied to the lower tray  250  and the shape of the lower tray  250  is deformed in the ice-removal process, the lower tray  250  may be returned to its original shape. Thus, the spherical ice may be generated despite the repeated ice generation. 
     Further, when the lower tray  250  is made of the silicone material, the lower tray  250  may be prevented from being melted or thermally deformed by heat provided from a lower heater to be described later. 
     In one example, the lower tray  250  may be made of the same material as the upper tray  150 , or may be made of a material softer than the material of the upper tray  150 . That is, when the lower tray  250  and the upper tray  150  come into contact with each other for the ice-making, since the lower tray  250  has a lower hardness, while the top of the lower tray  250  is deformed, the upper tray  150  and the lower tray  250  may be pressed and sealed with each. 
     Further, since the lower tray  250  has a structure that is repeatedly deformed by direct contact with the lower ejector  400 , the lower tray  250  may be made of a material having a low hardness to facilitate the deformation. 
     However, when the hardness of the lower tray  250  is too low, another portion of the lower chamber  252  may be deformed too. Thus, it is preferable that the lower tray  250  is formed to have an appropriate hardness to maintain the shape. 
     The lower tray  250  may include a lower tray body  251  that forms a lower chamber  252  that is a portion of the ice chamber  111 . The lower tray body  251  may form a plurality of lower chambers  252 . 
     In one example, the plurality of lower chambers  252  may include a first lower chamber  252   a , a second lower chamber  252   b , and a third lower chamber  252   c.    
     The lower tray body  251  may include three chamber walls  252   d  forming the three independent lower chambers  252   a ,  252   b , and  252   c . The three chamber walls  252   d  may be formed integrally to form the lower tray body  251 . Further, the first lower chamber  252   a , the second lower chamber  252   b , and the third lower chamber  152   c  may be arranged in series. 
     The lower chamber  252  may be formed in a hemispherical form or a form similar to the hemisphere. That is, a lower portion of the spherical ice may be formed by the lower chamber  252 . Herein, the form similar to the hemisphere means a form that is not a complete hemisphere but is almost close to the hemisphere. 
     The lower tray  250  may further include a lower tray mounting face  253  extending horizontally from a top edge of the lower tray body  251 . The lower tray mounting face  253  may be formed continuously along a circumference of the top of the lower tray body  251 . Further, in coupling with the upper tray  150 , the lower tray mounting face  253  may be in close contact with the top face  153   c  of the upper tray  150 . 
     The lower tray  250  may further include a side wall  260  extending upwardly from an outer end of the lower tray mounting face  253 . Further, the side wall  260  may surround the upper tray body  151  seated on the top face of the lower tray body  251  in a state in which the upper tray  150  and the lower tray  250  are coupled together. 
     The side wall  260  may include a first wall  260   a  surrounding the vertical wall  153   a  of the upper tray body  151  and a second wall  260   b  surrounding the curved wall  153   b  of the upper tray body  151 . 
     The first wall  260   a  is a vertical wall extending vertically from the top face of the lower tray mounting face  253 . The second wall  260   b  is a curved wall formed in a shape corresponding to the upper tray body  151 . That is, the second wall  260   b  may be rounded upwardly from the lower tray mounting face  253  in a direction farther away from the lower chamber  252 . Further, the second wall  206   b  is formed to have a curvature corresponding to the curved wall  153   b  of the upper tray body  151 , so that the lower assembly  200  may maintain a predetermined distance from the upper assembly  110  and may not interfere with the upper assembly  110  in a process of being pivoted. 
     The lower tray  250  may further include a tray horizontal extension  254  extending in the horizontal direction from the side wall  260 . The tray horizontal extension  254  may be positioned higher than the lower tray mounting face  253 . Thus, the lower tray mounting face  253  and the tray horizontal extension  254  form a step. 
     The tray horizontal extension  254  may include a first upper protrusion  255  formed thereon to be inserted into the slot  218  of the lower casing  210 . The first upper protrusion  255  may be spaced apart from the side wall  260  in the horizontal direction. 
     In one example, the first upper protrusion  255  may protrude upward from the top face of the tray horizontal extension  254  at a location adjacent to the first wall  260   a . The plurality of first upper protrusions  255  may be spaced apart from each other. The first upper protrusion  255  may extend, for example, in a curved form. 
     The tray horizontal extension  254  may further include a first lower protrusion  257  formed thereon to be inserted into a protrusion groove of the lower support  270  to be described later. The first lower protrusion  257  may protrude downward from a bottom face of the tray horizontal extension  254 . A plurality of first lower protrusions  257  may be spaced apart from each other. 
     The first upper protrusion  255  and the first lower protrusion  257  may be located on opposite sides of the tray horizontal extension  254  in the vertical direction. At least a portion of the first upper protrusion  255  may overlap the second lower protrusion  257  in the vertical direction. 
     In one example, the tray horizontal extension  254  may include a plurality of through-holes  256  defined therein. The plurality of through-holes  256  may include a first through-hole  256   a  through which the first coupling boss  216  of the lower casing  210  penetrates, and a second through-hole  256   b  through which the second coupling boss  217  of the lower casing  210  penetrates. 
     A plurality of first through-holes  256   a  and a plurality of second through-holes  256   b  may be located opposite to each other around the lower chamber  252 . Some of the plurality of second through-holes  256   b  may be located between two adjacent first upper protrusions  255 . Further, some of the remaining second through-holes  256   b  may be located between two adjacent first lower protrusions  257 . 
     The tray horizontal extension  254  may further include a second upper protrusion  258 . The second upper protrusion  258  may be located opposite to the first upper protrusion  255  around the lower chamber  252 . 
     The second upper protrusion  258  may be spaced apart from the side wall  260  in the horizontal direction. In one example, the second upper protrusion  258  may protrude upward from the top face of the tray horizontal extension  254  at a location adjacent to the second wall  260   b.    
     The second upper protrusion  258  may be received in the receiving groove  218   a  of the lower casing  210 . The second upper protrusion  258  may be in contact with the curved portion  215  of the lower casing  210  in a state in which the second upper protrusion  258  is received in the receiving groove  218   a.    
     The side wall  260  of the lower tray  250  may include a first coupling protrusion  262  for coupling with the lower casing  210  formed thereon. 
     The first coupling protrusion  262  may protrude in the horizontal direction from the first wall  260   a  of the side wall  260 . The first coupling protrusion  262  may be located on an upper portion of a side of the first wall  260   a.    
     The first coupling protrusion  262  may include neck portion  262   a  which is reduced in diameter compared to other portions. The neck portion  262   a  may be inserted into the first coupling slit  214   b  which is defined in the side wall  214  of the lower casing  210 . 
     The side wall  260  of the lower tray  250  may further include a second coupling protrusion  261 . The second coupling protrusion  261  may be coupled with the lower casing  210 . 
     The second coupling protrusion  261  may protrude from the second wall  260   b  of the side wall  260  and may be formed in a direction opposite to the first coupling protrusion  262 . Further, the first coupling protrusion  262  and the second coupling protrusion  261  may be arranged to face away from each other around a center of the lower chamber  252 . Thus, the lower tray  250  may be firmly fixed to the lower casing  210 , and in particular, deviation and deformation of the lower chamber  252  may be prevented. 
     The tray horizontal extension  254  may further include a second lower protrusion  266 . The second lower protrusion  266  may be positioned opposite the second lower protrusion  257  around the lower chamber  252 . 
     The second lower protrusion  266  may protrude downward from the bottom face of the tray horizontal extension  254 . The second lower protrusion  266  may extend, for example, in a straight line form. Some of the plurality of first through-holes  256   a  may be located between the second lower protrusion  266  and the lower chamber  252 . The second lower protrusion  266  may be received in a guide groove defined in the lower support  270  to be described later. 
     The tray horizontal extension  254  may further include a lateral stopper  264 . The lateral stopper  264  restricts a horizontal movement of the lower tray  250  in a state in which the lower casing  210  and the lower support  270  are coupled with each other. 
     The lateral stopper  264  protrudes laterally from the side of the tray horizontal extension  254 , and a vertical length of the lateral stopper  264  is larger than a thickness of the tray horizontal extension  254 . In one example, a portion of the lateral stopper  264  is positioned higher than the top face of the tray horizontal extension  254 , and another portion thereof is positioned lower than the bottom face of the tray horizontal extension  254 . 
     Thus, a portion of the lateral stopper  264  may be in contact with a side of the lower casing  210  and another portion thereof may be in contact with a side of the lower support  270 . The lower tray body  251  may further include a convex portion  25  lb having an upwardly convex lower portion. That is, the convex portion  251   b  may be disposed to be convex inwardly of the ice chamber  111 . 
     In one example, the lower support  270  may include a support body  271  for supporting the lower tray  250 . 
     The support body  271  may include three chamber-receiving portions  272  defined therein for respectively accommodating the three chamber walls  252   d  of the lower tray  250  therein. The chamber-receiving portion  272  may be defined in a hemispherical shape. 
     The support body  271  may include a lower opening  274  defined therein to be penetrated by the lower ejector  400  in the ice-removal process. In one example, three lower openings  274  may be defined in the support body  271  to respectively correspond to the three chamber-receiving portions  272 . A reinforcing rib  275  for strength reinforcement may be formed along a circumference of the lower opening  274 . 
     A lower support step  271   a  for supporting the lower tray mounting face  253  may be formed on a top of the support body  271 . Further, the lower support step  271   a  may be formed to be stepped downward from a lower support top face  286 . Further, the lower support step  271   a  may be formed in a shape corresponding to the lower tray mounting face  253 , and may be formed along a circumference of a top of the chamber-receiving portion  272 . 
     The lower tray mounting face  253  of the lower tray  250  may be seated in the lower support step  271   a  of the support body  271 , and the lower support top face  286  may surround the side of the lower tray mounting face  253  of the lower tray  250 . In this connection, a face connecting the lower support top face  286  with the lower support step  271   a  may be in contact with the side of the lower tray mounting face  253  of the lower tray  250 . 
     The lower support  270  may further include a protrusion groove  287  defined therein for accommodating the first lower protrusion  257  of the lower tray  250 . The protrusion groove  287  may extend in a curved shape. The protrusion groove  287  may be formed, for example, in the lower support top face  286 . 
     The lower support  270  may further include a first fastener groove  286   a  into which a first fastener B  1  passed through the first coupling boss  216  of the upper casing  210  is fastened. The first fastener groove  286   a  may be defined, for example, in the lower support top face  286 . Some of a plurality of first fastener grooves  286   a  may be located between two adjacent protrusion grooves  287   a.    
     The lower support  270  may further include an outer wall  280  disposed to surround the lower tray body  251  while being spaced apart from the outer face of the lower tray body  251 . The outer wall  280  may, for example, extend downwardly along an edge of the lower support top face  286 . 
     The lower support  270  may further include a plurality of hinge bodies  281  and  282  to be respectively connected to hinge supports  135  and  136  of the upper casing  210 . The plurality of hinge bodies  281  and  282  may be spaced apart from each other. Since the hinge bodies  281  and  282  differ only in mounting positions thereof, and structures and shapes thereof are identical, only a hinge body  292  at one side will be described. 
     Each of the hinge bodies  281  and  282  may further include a second hinge hole  282   a  defined therein. The second hinge hole  282   a  may be penetrated by a shaft connector  352   b  of the rotating arms  351  and  352 . The connection shaft  370  may be connected to the shaft connector  352   b.    
     Further, each of the hinge bodies  281  and  282  may include a pair of hinge ribs  282   b  protruding along a circumference of each of the hinge bodies  281  and  282 . The hinge rib  282   b  may reinforce the hinge bodies  281  and  282  and prevent the hinge bodies  281  and  282  from breaking. 
     The lower support  270  may further include a coupling shaft  283  to which the link  356  is rotatably connected. A pair of coupling shafts  383  may be provided on both faces of the outer wall  280 , respectively. 
     Further, the lower support  270  may further include an elastic member receiving portion  284  to which the elastic member  360  is coupled. The elastic member receiving portion  284  may define a space  284   a  in which a portion of the elastic member  360  may be accommodated. As the elastic member  360  is received in the elastic member receiving portion  284 , the elastic member  360  may be prevented from interfering with a surrounding structure. 
     Further, the elastic member receiving portion  284  may include a stopper  284   a  to which a bottom of the elastic member  370  is hooked. Further, the elastic member receiving portion  284  may include an elastic member shield  284   c  that covers the elastic member  360  to prevent insertion of a foreign material or fall of the elastic member  360 . 
     In one example, a link shaft  288  to which one end of the link  356  is rotatably coupled may protrude at a position between the elastic member receiving portion  284  and each of the hinge bodies  281  and  282 . The link shaft  288  may be provided forward and downward from a center of rotation of each of the hinge bodies  281  and  282 . With such arrangement, a vertical stroke of the upper ejector  300  may be secured, and the link  356  may be prevented from interfering with other components. 
     Hereinafter, the coupling structure of the lower tray  250  and the lower casing  210  will be described in more detail with reference to the accompanying drawings. 
       FIG.  32    is a partial perspective view illustrating a protruding confiner of a lower casing according to an embodiment of the present disclosure. Further,  FIG.  33    is a partial perspective view illustrating a coupling protrusion of a lower tray according to an embodiment of the present disclosure. Further,  FIG.  34    is a cross-sectional view of a lower assembly. Further,  FIG.  35    is a cross-sectional view of  FIG.  27    taken along a line  35 - 35 ′. 
     As shown in  FIGS.  32  to  35   , a protruding confiner  213  may protrude from the curved wall  215  of the upper casing  120 . The protruding confiner  213  may be formed at a location corresponding to the second coupling slit  215   a  and the second coupling protrusion  261 . 
     In detail, the protruding confiner  213  may include a pair of lateral portions  213   b  and a connector  213   c  connecting tops of the lateral portions  213   b  with each other. The pair of lateral portions  213   b  may be located on both sides around the second coupling slit  215   a . Thus, the second coupling slit  215   a  may be located in an insertion space  213   a  defined by the pair of lateral portions  213   b  and the connector  213   c . Further, the second coupling protrusion  261  may be inserted into the insertion space  213   a . Thus, the lower portion of the second coupling protrusion  261  may be press-fitted into the second coupling slit  215   a.    
     The pair of lateral portions  213   b  may extend to a vertical level corresponding to the top of the second coupling protrusion  261 . Further, a confining rib  213   d  extending downwards may be formed inside the connector  213   c.    
     The confining rib  213   d  may be inserted into the protrusion groove  261   d  defined in the top of the second coupling protrusion  261 , and may restrain the second coupling protrusion  261  from falling. As such, both the upper and lower portions of the second coupling protrusion  261  may be fixed, and the lower tray  250  may be firmly fixed to the lower casing  210 . 
     The second coupling protrusion  261  may protrude outwardly of the second wall  260   b , and a thickness thereof may increase upwardly. That is, due to a self-load of the second coupling protrusion  261 , the second wall  260   b  does not roll inward or deform, and the top of the second wall  260   b  is pulled outward. 
     Thus, in a process in which the lower tray  250  pivots in a reverse direction, the second coupling protrusion  261  prevents an end of the second wall  260   b  of the lower tray  250  from deforming in contact with the upper tray  150 . 
     When the end of the second wall  260   b  of the lower tray  250  is deformed in contact with the upper tray  150 , the lower tray  250  may be moved to a water-supply position while being inserted into the upper chamber  152  of the upper tray  150 . In this state, when the ice-making is completed after the water supply is performed, the ice is not produced in the spherical form. 
     Thus, when the second coupling protrusion  261  protrudes from the second wall  260   a , the deformation of the second wall  260   a  may be prevented. Thus, the second coupling protrusion  261  may be referred to as a deformation preventing protrusion. 
     The second coupling protrusion  261  may protrude in the horizontal direction from the second wall  260   a . The second coupling protrusion may extend upward from a lower portion of the outer face of the second wall  260   b , and a top of the second coupling protrusion  261  may extend to the same vertical level as the top of the second wall  260   a.    
     Further, the second coupling protrusion  261  may include a protrusion lower portion  261   a  forming a lower portion thereof and a protrusion upper portion  261   b  forming an upper portion thereof. 
     The protrusion lower portion  261   a  may be formed to have a corresponding width to be inserted into the second coupling slit  215   a . Thus, when the second coupling protrusion  261  is inserted into the insertion space of the protruding confiner  213 , the protrusion lower portion  261   a  may be press-fitted into the second coupling slit  215   a.    
     The protrusion upper portion  261   b  extends upward from a top of the protrusion lower portion  261   a . The protrusion upper portion  261   b  may extend upward from a top of the second coupling slit  215   a , and may extend to the connector  213   c . In this connection, the protrusion upper portion  261   b  may protrude further rearward than the protrusion lower portion  261   a , and may have a width larger than that of the protrusion lower portion  261   a . Thus, the second wall  260   b  may be directed further outwards by a self-load of the protrusion upper portion  26  lb. That is, the protrusion upper portion  261   b  may pull the top of the second wall  260   b  outward to maintain the outer face of the second wall  260   b  and the curved wall  153   b  to be in close contact with each other. 
     Further, a protrusion groove  261   d  may be defined in a top face of the protrusion upper portion  261   b , that is, a top face of the second coupling protrusion  261 . The protrusion groove  261   d  is defined such that the confining rib  213   d  extending downward from the connector  213   c  may be inserted therein. 
     Thus, a bottom of the second coupling protrusion  261  may be pressed into the second coupling slit  215   a  and a top thereof may be restrained by the connector  213   c  and the confining rib  213   d  in a state of being received inside the insertion space  213   a . Thus, the second coupling protrusion  261  may be in a state of being completely in close contact with and fixed to the lower casing  210  so as not to be in contact with the upper tray  150  during the pivoting process of the lower tray  250 . 
     A round face  260   e  may be formed on the top of the second coupling protrusion  261  to prevent the second coupling protrusion  261  from interfering with the upper tray  150  in the pivoting process of the lower tray  250 . 
     A lower portion  260   d  of the second coupling protrusion  261  may be spaced apart from the tray horizontal extension  254  of the lower tray  250  such that the lower portion  260   d  of the second coupling protrusion  261  may be inserted into the second coupling slit  215   a.    
     In one example, as shown in  FIG.  35   , the lower support  270  may further include a boss through-hole  286   b  to be penetrated by the second coupling boss  217  of the upper casing  210 . The boss through-hole  286   b  may be, for example, defined in the lower support top face  286 . The lower support top face  286  may include a sleeve  286   c  surrounding the second coupling boss  217  passed through the boss through-hole  286   b . The sleeve  286   c  may be formed in a cylindrical shape with an open bottom. 
     The first fastener B 1  may be fastened into the first fastener groove  286   a  after passing through the first coupling boss  216  from upward of the lower casing  210 . Further, the second fastener B 2  may be fastened to the second coupling boss  217  from downward of the lower support  270 . 
     A bottom of the sleeve  286   c  may be positioned flush with the bottom of the second coupling boss  217  or lower than the bottom of the second coupling boss  217 . 
     Thus, in the fastening process of the second fastener B 2 , a head of the second fastener B 2  may be in contact with the second coupling boss  217  and a bottom face of the sleeve  286   c  or in contact with the bottom face of the sleeve  286   c.    
     The lower casing  210  and the lower support  270  may be firmly coupled to each other by the fastening of the first fastener B 1  and the second fastener B 2 . Further, the lower tray  250  may be fixed between the lower casing  210  and the lower support  270 . 
     In one example, the lower tray  250  comes into contact with the upper tray  150  by the pivoting, and the upper tray  150  and the lower tray may always be sealed with each other during the ice-making. Hereinafter, a sealing structure based on the pivoting of the lower tray  250  will be described in detail with reference to the accompanying drawings. 
       FIG.  36    is a plan view of a lower tray. Further,  FIG.  37    is a perspective view of a lower tray according to another embodiment of the present disclosure. Further,  FIG.  38    is a cross-sectional view that sequentially illustrates a pivoting state of a lower tray. Further,  FIG.  39    is a cross-sectional view showing states of an upper tray and a lower tray immediately before or during ice-making. Further,  FIG.  40    shows states of upper and lower trays upon completion of ice-making. 
     Referring to  FIGS.  36  to  40   , the lower chamber  252  opened upwards may be defined in the lower tray  250 . Further, the lower chamber  252  may include the first lower chamber  252   a , the second lower chamber  252   b , and the third lower chamber  252   c  arranged in series. Further, the side wall  260  may extend upward along the perimeter of the lower chamber  252 . 
     In one example, the lower tray mounting face  253  may be formed along a perimeter of top of the lower chamber  252 . The lower tray mounting face  253  forms a face that is in contact with the bottom face  153   c  of the upper tray  150  when the lower tray  250  is pivoted and closed. 
     The lower tray mounting face  253  may be formed in a planar shape, and may be formed to connect the tops of the lower chambers  252  with each other. Further, the side wall  260  may extend upwardly along the outer end of the lower tray mounting face  253 . 
     A lower rib  253   a  may be formed on the lower tray mounting face  253 . The lower rib  253   a  is for sealing between the upper tray  150  and the lower tray  250 , which may extend upward along the perimeter of the lower chamber  252 . 
     The lower rib  253   a  may be formed along the circumference of each of the lower chambers  252 . Further, the lower rib  253   a  may be formed at a position to face away from the upper rib  153   d  in the vertical direction. 
     Further, the lower rib  253   a  may be formed in a shape corresponding to the upper rib  153   d . That is, the lower rib  253   a  may extend starting from a position separated by a predetermined distance from one end of the lower chamber  252 , which is close to the pivoting shaft of the lower tray  250 . Further, a height of the lower tray  250  may increase in a direction farther away from the pivoting shaft of the lower tray  250 . 
     The lower rib  253   a  may be in close contact with the inner face of the upper tray  150  in a state in which the lower tray  250  is completely closed. For this purpose, the lower rib  253   a  protrudes upwards from the top of the lower chamber  252 , and may be flush with the inner face of the lower chamber  252 . Thus, in a state in which the lower tray  250  closed, as shown in  FIG.  39   , an outer face of the lower rib  253   a  may come into contact with an inner face of the upper rib  153   d , and the upper tray  150  and the lower tray  250  may be completely sealed with each other. 
     In this connection, due to the driving of the driver  180 , the first rotating arm  351  and the second rotating arm  352  may be further rotated, and the elastic member  360  may be tensioned to press the lower tray  250  toward the upper tray  150 . 
     When the upper tray  150  and the lower tray  250  are further closed by the pressurization of the elastic member  360 , the upper rib  153   d  and the lower rib  253   a  may be bent inward to allow the upper tray  150  and the lower tray  250  to be further sealed with each other. 
     In one example, before the ice-making, when the lower tray  250  is filled with water, and when the lower tray  250  is closed as shown in  FIG.  39   , the upper rib  153   d  and the lower rib  253   a  may overlap and sealed. In this connection, the top of the lower rib  253   a  may come into contact with an inner face of the bottom of the upper chamber  152  of the upper tray  150 . Therefore, a step of a coupling portion inside the ice chamber  111  may be minimized to generate the ice. 
     In order to fill the water in all of the plurality of ice chambers  111 , the water is supplied in a state in which the lower tray  250  is slightly open. Then, when the water supply is complete, the lower tray  250  is pivoted and closed as shown in  FIG.  39   . Accordingly, the water may flow into spaces G 1  and G 2  defined between the side wall  260  and the chamber wall  153  and be filled to a water level the same as that in the ice chamber  111 . Further, the water in the spaces G 1  and G 2  between the side wall  260  and the chamber wall  153  may be frozen during the ice-making operation. 
     However, the ice chamber  111  and the spaces G 1  and G 2  may be completely separated from each other by the upper rib  153   d  and the lower rib  253   a , and may maintain the separated state by the upper rib  153   d  and the lower rib  253   a  even when the ice-making is completed. Therefore, the ice strip may not be formed on the ice made in the ice chamber  111 , and the ice may be removed in a state of being completely separated from ice debris in the spaces G 1  and G 2 . 
     When viewing a state in which the ice-making is completed in the ice chamber  111  through  FIG.  40   , due to the expansion of the water resulted from the phase-change, the lower tray  250  is inevitably opened at a certain angle. However, the upper rib  153   d  and lower rib  253   a  may remain in contact with each other, and thus, the ice inside the ice chamber  111  will not be exposed into the space. That is, even when the lower tray  250  is slowly opened during the ice-making process, the upper tray  150  and the lower tray  250  may be maintained to be shielded by the upper rib  153   d  and the lower rib  253   a , thereby forming the spherical ice. 
     In one example, as shown in  FIG.  40   , when the ice-making is completed and the lower tray  250  is opened at the maximum angle, the upper tray  150  and the lower tray  250  may be separated from each other by approximately 0.5 to 1 mm. Therefore, a length of the lower rib  253   a  is preferably approximately 0.3 mm. In another example, a height of the lower rib  253   a  is only an example, and the lengths of the upper rib  153   d  and the lower rib  253   a  may be appropriately selected depending on the distance between the upper tray  150  and the lower tray  250 . 
     Further, when an area of the lower tray mounting face  253  is large enough, a pair of lower ribs  253   a  and  253   b  may be formed on the lower tray mounting face  253 . The pair of lower ribs  253   a  and  253   b  may be formed in the same shape as the lower rib  253   a , but may be composed of an inner rib  253   b  disposed close to the lower chamber  252  and an outer rib  253   a  outward of the inner rib  253   b . The inner rib  253   b  and the outer rib  253   a  are spaced apart from each other to define a groove therebetween. Therefore, when the lower tray  250  is pivoted and closed, the upper rib  153   d  may be inserted into the groove between the inner rib  253   b  and the outer rib  253   a.    
     Due to such double-rib structure, the upper rib  153   d  and the lower ribs  253   a  and  253   b  may be more sealed with each other. However, such a structure may be applicable when the lower tray mounting face  253  is provided with sufficient space for the inner rib  253   b  and outer rib  253   a  to be formed. 
     In one example, the lower tray  250  may be pivoted about the hinge bodies  281  and  282 , and may be pivoted by an angle of about 140° such that the ice-removal may be achieved even when the ice is placed in the lower chamber  252 . The lower tray  250  may be pivoted as shown in  FIG.  38   . Even during such pivoting, the side wall  260  and chamber wall  153  should not interfere with each other. 
     More specifically, the water supply is inevitably performed in a state in which the lower tray  250  is slightly open for supplying the water into the plurality of the lower chambers  252 . In this situation, the side wall  260  of the lower tray  250  may extend upwards above a water-supply level in the ice chamber  111  to prevent water leakage. 
     Further, since the lower tray  250  opens and closes the ice chamber  111  by the pivoting, the spaces G 1  and G 2  are inevitably defined between the side wall  260  and the chamber wall  153 . When the spaces G 1  and G 2  between the side wall  260  and the chamber wall  153  are too narrow, interference with the upper tray  150  may occur during the pivoting process of the lower tray  250 . Further, when the spaces G 1  and G 2  between the side wall  260  and the chamber wall  153  are too wide, during the water supplying into the lower chamber  252 , an excessive amount of water is flowed into the spaces G 1  and G 2  and lost, and thus, an excessive amount of ice debris is generated. Therefore, widths of the spaces G 1  and G 2  between the side wall  260  and the chamber wall  153  may be equal to or less than about 0.5 mm. 
     In one example, the curved wall  153   b  of the upper tray  150  and the curved wall  260   b  of the lower tray  250  of the side wall  260  and the chamber wall  153  may be formed to have the same curvature. Thus, as shown in  FIG.  38   , the curved wall  153   b  of the upper tray  150  and the curved wall  260   b  of the lower tray  250  do not interfere with each other in an entire region where the lower tray  250  is pivoted. 
     In this connection, a radius R 2  of the curved wall  153   b  of the upper tray  150  is slightly larger than a radius R 1  of the curved wall  260   b  of the lower tray  250 , so that the upper tray  150  and lower tray  250  may have a water-supplyable structure without interfering with each other during the pivoting. 
     In one example, a center of pivoting C of the hinge bodies  281  and  282 , which is the axis of pivoting of the lower tray  250 , may be located somewhat lower than the top face  286  of the upper lower support  270  or the lower tray mounting face  253 . The bottom face  153   c  of the upper tray  150  and the lower tray mounting face  253  are in contact with each other when the lower tray  250  is pivoted and closed. 
     The lower tray  250  may have a structure to be in close contact with the upper tray  150  in the closing process. Therefore, when the lower tray  250  is pivoted and closed, a portion of the upper tray  150  and a portion of the lower tray  250  may be engaged with each other at a position close to the pivoting shaft of the lower tray  250 . In such a situation, even when the lower tray  250  is pivoted to be closed completely, ends of the upper tray  150  and the lower tray  250  at points far from the pivoting shaft may be separated from each other due to the interference in the engaged portion. 
     To solve such problem, the center of pivoting Cl of the hinge bodies  281  and  282 , which is the pivoting shaft of the lower tray  250 , is moved somewhat downward. For example, the center of pivoting Cl of the hinge bodies  281  and  282  may be located 0.3 mm below the top face of the lower support  270 . 
     Thus, when the lower tray  250  is closed, the ends of the upper tray  150  and the lower tray  250  close to the pivoting shaft may not be engaged with each other first, but the lower tray mounting face  253  and the entirety of the bottom face  153   c  of the upper tray  150  may be in close contact with each other. 
     In particular, since the upper tray  150  and the lower tray  250  are made of an elastic material, tolerances may occur during the assembly, or coupling may be loosened or micro deformation may occur during the use. However, such structure may solve the problem of the ends of the upper tray  150  and the lower tray  250  engaging with each other first. 
     In one example, the pivoting shaft of the lower tray  250  may be substantially the same as the pivoting shaft of the lower support  270 , and the hinge bodies  281  and  282  may also be formed on the lower support  270 . 
     Hereinafter, the upper ejector  300  and the connector  350  connected to the upper ejector  300  will be described with reference to the drawings. 
       FIG.  41    is a perspective view showing a state in which an upper assembly and a lower assembly are closed, according to an embodiment of the present disclosure. Further,  FIG.  42    is an exploded perspective view showing a coupling structure of a connector according to an embodiment of the present disclosure. Further,  FIG.  43    is a side view showing a disposition of a connector. Further,  FIG.  44    is a cross-sectional view of  FIG.  41    taken along a line  44 - 44 ′. 
     As shown in  FIGS.  41  and  44   , the upper ejector  300  is positioned at a topmost position when the lower assembly  200  and the upper assembly  110  are fully closed. Further, the connector  350  will remain stationary. 
     The connector  350  may be rotated by the driver  180 , and the connector  350  may be connected to the upper ejector  300  mounted on the upper support  170  and the lower support  270 . 
     Therefore, when the lower assembly  200  is opened in the pivoting, the upper ejector  300  may be moved downward by the connector  350  and may remove the ice in the upper chamber  152 . 
     The connector  350  may include a rotating arm  352  for rotating the lower support  270  under the power of the driver  180  and a link  356  connected to the lower support  270  to transfer a pivoting force of the lower support  270  to the upper ejector  300  when the lower support  270  pivots. 
     In detail, a pair of rotating arms  351  and  352  may be disposed at both sides of the lower support  270 , respectively. A second rotating arm  352  of the pair of rotating arms  351  and  352  may be connected to the driver  180 , and a first rotating arm  351  may be disposed opposite to the second rotating arm  352 . Further, the first rotating arm  351  and the second rotating arm  352  may be respectively connected to both ends of the connection shaft  370 , which pass through the hinge bodies  281  and  282  at both sides, respectively. Therefore, the first rotating arm  351  and the second rotating arm  352  may be rotated together when the driver  180  is operated. 
     To this end, the shaft connector  352   b  may protrude inwardly of each of the first rotating arm  351  and the second rotating arm  352 . Further, the shaft connector  352   b  may be coupled to second hinge holes  282   a  of the hinge body  282  in both sides. The second hinge hole  282   a  and the shaft connector  352   b  may be formed in structures to be coupled with each other to allow the transmission of the power. 
     In one example, the second hinge hole  282   a  and the shaft connector  352   b  may have shapes corresponding to each other, but may be formed to have a predetermined play ( FIG.  44   ) in the direction of rotation. Thus, when the lower assembly  200  is closed in pivoting, the driver  180  may be rotated further by a set angle while the lower tray  250  is in contact with the upper tray  150 , thereby further rotating the rotating arms  351  and  352 . The lower tray  250  may be further pressed toward the upper tray  150  by an elastic force of the elastic member  360  generated at this time. 
     In one example, a power connector  352   ac  that is coupled to a rotation shaft of the driver  180  may be formed on an outer face of the second rotating arm  352 . The power connector  352   a  may be formed in a polygonal hole, and the rotation shaft of the driver  180  formed in the corresponding shape may be inserted into the power connector  352   a  to allow the transmission of the power. 
     In one example, the first rotating arm  351  and second rotating arm  352  may extend above the elastic member receiving portion  284 . Further, the elastic member connectors  351   c  and  352   c  may be formed at the extended ends of the first rotating arm  351  and the second rotating arm  352 , respectively. One end of the elastic member  360  may be connected to each of the elastic member connectors  351   c  and  352   c . The elastic member  360  may be, for example, a coil spring. 
     The elastic member  360  may be located inside the elastic member receiving portion  284 , and the other end of the elastic member  360  may be fixed to a locking portion  284   a  of the lower support  270 . The elastic member  360  provides an elastic force to the lower support  270  to keep the upper tray  150  and the lower tray  250  in contact with each other in a pressed state. 
     The elastic member  360  may provide an elastic force that allows the lower assembly  200  to be in a close contact with the upper assembly  200  in a closed state. That is, when the lower assembly  200  pivots to close, the first rotating arm  351  and the second rotating arm  352  are also rotated together until the lower assembly  200  is closed, as shown in  FIG.  41   . 
     Further, in a state in which the lower assembly  200  is pivoted to a set angle and in contact with the upper assembly  200 , the first rotating arm  351  and the second rotating arm  352  may be further rotated by the rotation of the driver  180 . The rotation of the first rotating arm  351  and second rotating arm  352  may cause the elastic member  360  to be tensioned. Further, the lower assembly  200  may be further rotated in the closing direction by the elastic force provided by the elastic member  360 . 
     When the elastic member  360  is not provided and the lower assembly  200  is further pivoted by the driver  180  to press the lower assembly to the upper assembly  110 , an excessive load may be concentrated on the driver  180 . Further, when the water is phase-changed and expands and the lower tray  250  pivots in the open direction, a reverse force is applied to the gear of the driver  180 , so that the driver  180  may be damaged. Further, when the driver  180  is turned off, the lower tray  250  sags due to a play of the gears. However, all of these problems may be solved when the lower assembly  200  is pulled to be closed contacted by the elastic force provided by the elastic member  360 . 
     That is, the lower assembly  200  may be provided with the elastic force through the elastic member  360  in a tensioned state without additional power from the driver  180 , and may allow the lower assembly  200  to be closer to the upper assembly  110 . 
     Further, even when the lower tray  250  is stopped by the driver  180  before being fully pressed against the upper tray  150 , an elastic restoring force of the elastic member  360  allows the lower tray  250  to be pivoted further to be completely in contact with the upper tray  150 . In particular, an entirety of the lower tray  250  may be in close contact with the upper tray  150  without a gap by the elastic members  360  arranged on both sides. 
     The elastic member  360  will continuously provide the elastic force to the lower assembly  200 . Therefore, even when the ice is produced in the ice chamber  111  and expands, the elastic force is applied to the lower assembly  200 , so that the lower assembly  200  may not be excessively opened. 
     In one example, the link  356  may link the lower tray  250  and the upper ejector  300  with each other. The link  356  is formed in a bent shape, so that the link  356  does not interfere with each of the hinge bodies  281  and  282  during the pivoting process of the lower tray  250 . 
     A tray connector  356   a  may be formed at a bottom of the link  356 , and the link shaft  288  may pass through the tray connector  356   a . Thus, a bottom of the link  356  may be rotatably connected to the lower support  270 , and may rotate together upon the pivoting of the lower support  270 . 
     The link shaft  288  may be located between each of the hinge bodies  281  and  282  and the elastic member receiving portion  284 . Further, the link shaft  288  may be located further below a center of pivoting of each of the hinge bodies  281  and  282 . Therefore, the link shaft  288  may be positioned close to a vertical movement path of the upper ejector  300 , so that the upper ejector  300  may be effectively moved vertically. Further, the upper face  300  may descend to a required position, and at the same time, the upper ejector  300  may not be moved to an excessively high position when the upper ejector  300  moves upward. Therefore, heights of the upper ejector  300  and the unit guides  181  and  182  that are exposed upwardly of the ice maker  100  may be further lowered, so that an upper space lost when the ice maker  100  is installed in the freezing compartment  4  may be minimized. 
     The link shaft  288  protrudes vertically outward from an outer face of the lower support  270 . In this connection, the link shaft  288  may extend to pass through the tray connector  356   a , but may be covered by the rotating arms  351  and  352 . Each of the rotating arms  351  and  352  becomes very close to the link and the link shaft  288 . Thus, the link  356  may be prevented from being separated from the link shaft  288  by each of the rotating arms  351  and  352 . Each of the rotating arms  351  and  352  may shield the link shaft  288  at any point in the path of rotation. Thus, the rotating arms  351  and  352  may be formed to have a width enough to cover the link shaft  288 . 
     An ejector connector  356   b  through which an end of the ejector body  310 , that is, the stopper protrusion  312  passes may be formed on the top of the link  356 . The ejector connector  356   b  may also be rotatably mounted with the end of the ejector body  310 . Therefore, when the lower support  270  is rotated, the upper ejector  300  may be moved together in the vertical direction. 
     Hereinafter, states of the upper ejector  300  and the connector  350  based on the operation of the lower assembly  200  will be described with reference to the drawings. 
       FIG.  45    is a cross-sectional view of  FIG.  41    taken along a line  45 - 45 ′. Further,  FIG.  46    is a perspective view showing a state in which upper and lower assemblies are open. Further,  FIG.  47    is a cross-sectional view of  FIG.  46    taken along a line  47 - 47 ′. 
     As shown in  FIGS.  41  and  45   , during the ice-making of the ice maker  100 , the lower assembly  200  may be closed. 
     In this state, the upper ejector  300  is located at the topmost position, and the ejecting pin  320  may be located outward of the ice chamber  111 . Further, the upper tray  150  and the lower tray  250  may be completely in close contact with each other and sealed by the rotating arms  351  and  352  and the elastic member  360 . 
     In such state, the ice formation may proceed in the ice chamber  111 . 
     During the ice-making operation, the upper heater  148  and the lower heater  296  are operated periodically, so that the ice formation proceeds from the upper portion of the ice chamber  111 , thereby producing the transparent spherical ice. Further, when the ice formation is completed inside the ice chamber  111 , the driver  180  is operated to rotate the lower assembly  200 . 
     As shown in  FIGS.  46  and  47   , during the ice-removal of the ice maker  100 , the lower assembly  200  may be open. The lower assembly  200  may be fully opened by the operation of the driver  180 . 
     When the lower assembly  200  opens in the open direction, the bottom of the link  356  rotates with the lower tray  250 . Further, the top of the link  356  moves downward. The top of the link  356  may be connected to the ejector body  310  to move the upper ejector  300  downward, and may be moved downward without being guided by the unit guides  181  and  182 . 
     When the lower assembly  200  is fully pivoted, the ejecting pin  320  of the upper ejector  300  may pass through the ejector-receiving opening  154  and move to the bottom of the upper chamber  152  or a position adjacent thereto to remove the ice from the upper chamber  152 . In this connection, the link  356  is also rotated to the maximum angle, but the link  356  has a bent shape, and at the same time, the link shaft  288  may be located forwards and downwards of each of the hinge bodies  281  and  282 , so that interference of the link  356  with other components may be prevented. 
     In one example, the lower assembly  200  may partially sag while in a closed state. In detail, in the present embodiment, the driver  180  has a structure of being connected to the second rotating arm  352  among the rotating arms  351  and  352  on both sides, and the second rotating arm  352  has a structure of being connected to the first rotating arm  351  by the connection shaft  370 . Therefore, the rotational force is transmitted to the first rotating arm  351  through the connection shaft  370 , so that the first rotating arm  351  and the second rotating arm  352  may rotate simultaneously. 
     However, the first rotating arm  351  has a structure of being connected to the connection shaft  370 , Further, for the connection, a tolerance inevitably occurs at a connected portion. Such tolerance may cause slippage during the rotation of the connection shaft  370 . 
     In addition, since the lower assembly  200  extends in the direction of power transmission, a portion of the first rotating arm  351  positioned at a relatively far may sag, and a torque may not be 100% transmitted thereto. 
     Because of such structure, when the first rotating arm  351  rotates less than the second rotating arm  352 , the upper tray  150  and the lower tray  250  are not completely in contact with each other and sealed, and there is a region partially open between the upper tray  150  and the lower tray  250  at a side close to the first rotating arm  351 . Therefore, when the lower tray  250  sags or tilts, and thus, a water surface inside the ice chamber  111  is tilted, the spherical ice of a uniform size and shape may not be generated. Further, when water leaks through open portion, more serious problems may be caused. 
     To avoid such problem, a vertical level of the extended top of the first rotating arm  351  may be different from that of the extended top of the second rotating arm  352 . 
     Referring to  FIGS.  48 ,  49 , and  50   , a vertical level h 2  from the bottom face of the lower assembly  200  to the elastic member connector  351   c  of the first rotating arm  351  may be higher than a vertical level h 3  from the bottom face of the lower assembly  200  to the elastic member connector  352   c  of the second rotating arm  352 . 
     Thus, when the lower assembly  200  pivots to be closed, the first rotating arm  351  and second rotating arm  352  rotate together. Further, because the vertical level of the first rotating arm is high, when the lower tray  250  and the upper tray  150  begin to be in contact with each other, the elastic member  360  connected to the first rotating arm  351  is further tensioned. 
     That is, in a state in which the lower tray  250  is completely in contact with the upper tray  150 , the elastic force of the elastic member  360  of the first rotating arm  351  becomes greater. This compensates for the sagging of the lower tray  250  at the first rotating arm  351 . Thus, the entirety of the top face of the lower tray  250  may be in close contact and sealed with the bottom face of the upper tray  150 . 
     In particular, in a structure where the driver  180  is located on one side of the lower tray  250  and is directly connected only to the second rotating arm  352 , due to the tolerance occurred in the assembly of the connection shaft  370 , the first rotating arm  351  may be less rotated. However, as in the embodiment of the present disclosure, the first rotating arm  351  rotates the lower tray  250  with a force greater than that of the second rotating arm  352 , so that the lower tray  250  is prevented from sagging or less rotating. 
     In another example, the first rotating arm  351  and second rotating arm  352  may be rotationally coupled both ends of the connection shaft  370  respectively to be alternated with each other by a set angle with respect to the connection shaft  370 . Thus, the top of the first rotating arm  351  may be positioned higher than the top of the second rotating arm  352 . 
     Further, in another example, shapes of the first rotating arm  351  and the second rotating arm  352  may be different from each other such that the first rotating arm  351  extends longer than the second rotating arm  352 , and thus, a point where the first rotating arm  351  is connected to the elastic member  360  becomes higher than a point where the second rotating arm  352  is connected to the elastic member  360 . 
     Further, in another example, an elastic modulus of the elastic member  360  connected to the first rotating arm  351  may be made larger than an elastic modulus of the elastic member  360  connected to the second rotating arm  352 . 
     When the lower assembly  200  is completely closed, as shown in  FIG.  50   , the top of the lower casing  210  and the bottom of the upper support  170  may be spaced apart from each other by a predetermined distance h 4 . Further, a portion of the upper tray  150  may be exposed through the gap. In this connection, the space is defined between the upper casing  210  and the upper support  170 , but the upper tray  150  and the lower tray  250  remain in close contact with each other. 
     In other words, even when the upper tray  150  and the lower tray  250  are completely in contact and sealed with each other, the top of the lower casing  210  and the bottom of the upper support  170  may be spaced apart from each other. 
     When the top of the lower casing  210  and the bottom of the upper support  170 , which are injection-molded structures, are in contact with each other, an impact may strain and damage the driver  180 . 
     Further, when the top of the lower casing  210  and the bottom of the upper support  170  are spaced apart from each other, a space where the upper tray  150  and the lower tray  250  may be pressed and deformed may be defined. Therefore, in order to ensure close contact between the upper tray  150  and the lower tray  250  in various situations, such as the assembly tolerance and the deformation on use, the top of the lower casing  210  and the bottom of the upper support  170  must be spaced apart from each other. To this end, the side wall  260  of the lower tray  250  may extend higher than the top of the upper casing  120 . 
     Hereinafter, a structure of an upper ejector  300  will be described with reference to the drawings. 
       FIG.  50    is a front view of an ice maker. Further,  FIG.  51    is a partial cross-sectional view showing a coupling structure of an upper ejector. 
     As shown in  FIGS.  50  and  51   , the ejector body  310  has passing-through portions  311  at both ends thereof, and the passing-through portion  311  may pass through the guide slot  183  and the ejector connector  356   b . Further, a pair of stopper protrusions  312  may protrude in opposite directions from both ends of the ejector body  310 , that is, from respective ends of the passing-through portions  311 , respectively. Thus, each of the both ends of the ejector body  310  may be prevented from being separated from the ejector connector  356   b . Further, the stopper protrusion  312  abuts an outer face of the link  356  and extends vertically to prevent generation of the play between the stopper protrusion  312  and the link  356 . 
     Further, a body protrusion  313  may be further formed on the ejector body  310 . The body protrusion  313  may protrude downwardly at a position spaced apart from the stopper protrusion  312  and may extend to be in contact with an inner face of the link  356 . The body protrusion  313  may be inserted into the guide slot  183 , and may protrude by a predetermined length to be in contact with the inner face of the link  356 . 
     In this connection, the stopper protrusion  312  and the body protrusion  313  may respectively abut both faces of the link  356 , and may be arranged to face each other. Thus, the both face of the link may be supported by the stopper protrusion  312  and the body protrusion  313 , thereby effectively preventing the link  356  from moving. 
     When the ejector body  310  moves in a horizontal direction, the position of the ejecting pin  320  may be moved in the horizontal direction. Thus, the ejecting pin  320  may press the upper tray  150  in a process of passing through the ejector-receiving opening  154 , so that the upper tray  150  may be deformed or detached. Further, the ejecting pin  320  may get caught in the upper tray  150  and may not move. 
     Thus, in order to ensure that the ejecting pin  320  exactly passes through a center of the ejector-receiving opening  154  without moving, the stopper protrusion  312  and the body protrusion  313  may prevent the link  356  from moving, so that the ejecting pin  320  may move vertically a set position. 
     In addition, as shown in  FIG.  15   , a first stopper  139   ba  and a second stopper  189   bb  may be provided at the first through-opening  139   b  of the upper casing  120  through which the pair of the unit guides  181  and  182  are passed, and a third stopper  189   ca  and a fourth stopper  189   cb  are provided at the second through-opening  139   c , so that the movement of the unit guides  181  and  182  that guide the vertical movement of the ejector body  310  may also be prevented. 
     Therefore, the present embodiment has a structure that prevents the movements of not only the ejector body  310  but also of the unit guides  181  and  182 , and the ejecting pin  320 , which moves a relatively long distance in the vertical direction, does not move and enters the ejector-receiving opening  154  along a set path, so that contact or interference with the upper tray  150  may be completely prevented. 
     Hereinafter, a mounting structure of the driver  180  will be described with reference to the drawings. 
       FIG.  52    is an exploded perspective view of a driver according to an embodiment of the present disclosure. Further,  FIG.  53    is a partial perspective view showing a driver being moved for provisional fixing of a driver. Further,  FIG.  54    is a partial perspective view of a driver, which has been provisionally-fixed. Further,  FIG.  55    is a partial perspective view for showing restraint and coupling of a driver. 
     As shown in  FIGS.  52  to  55   , the driver  180  may be mounted on an inner face of the upper casing  120 . The driver  180  may be disposed adjacent to a side wall  143  far away from the cold-air hole  134 , that is, the second side wall. 
     In one example, the driver  180  may have a pair of fixed protrusions  185   a  protruding from the top face. The fixed protrusion  185   a  may be formed in a plate shape. The fixed protrusion  185   a  may extend in a direction from the top face of the driver casing  185  to the cold-air hole  134 . 
     Further, the rotation shaft  186  of the driver  180  may protrude in the protruding direction of the fixed protrusion  185   a . Further, a lever connector  187  to which the ice-full state detection lever  700  is mounted may be formed on one side away from the rotation shaft  186 . The top face of the driver casing  185  may further include a screw-receiving portion  185   b  formed thereon a through which a screw B 3  for fixing the driver  180  penetrates. 
     An opening  149   c  may be defined in a bottom face of the upper plate  121  of the upper casing  120  in which the driver  180  is mounted. The opening  149   c  is defined such that the screw-receiving portion  185   b  may be passed therethrough. Further, a screw groove  149   d  may be defined at one side of the opening  149   c.    
     Further, a driver mounted portion  149   a  on which the driver  180  is seated may be formed on the bottom face of the upper plate  121 . The driver mounted portion  149   a  may be located closer to the cold-air hole  134  than the opening  149   c , and the driver mounted portion  149   a  may further include an electrical-wire receiving hole  149   e  defined therein through which the electrical-wire connected to the driver  180  enters. 
     Further, the bottom face of the upper plate  121  may be formed with a fixed protruding confiner  149   b  into which the fixed protrusion  185   a  is inserted. The fixed protruding confiner  149   b  is positioned closer to the cold-air hole  134  than the driver mounted portion  149   a . Further, the fixed protruding confiner  149   b  may have an insertion hole opening defined therein in a corresponding shape such that the fixed protrusion  185   a  may be inserted therein. 
     Hereinafter, a mounting process of the driver  180  having the structure as described above will be described. 
     As shown in the  FIG.  52   , the operator directs the top face of the driver  180  to the inner side of the upper casing  120 , and insert the driver  180  into a mounting position of the driver  180 . 
     Next, as shown in the  FIG.  53   , the operator moves the driver  180  horizontally toward the cold-air hole  134  in a state in which the fixed protrusion  185   a  is in close contact with the driver mounted portion  149   a . The fixed protrusion  185   a  is inserted into the fixed protruding confiner  149   b  through such moving operation. 
     When the fixed protrusion  185   a  is fully inserted, as shown in  FIG.  54   , the fixed protrusion  185   a  is fixed inside the fixed protruding confiner  149   b . Further, the top face of the driver casing  185  may be seated on the driver mounted portion  149   a.    
     In this state, as shown in  FIG.  55   , the screw-receiving portion  185   b  may protrude upward and be exposed through the opening  149   c . Further, the screw B 3  is inserted and fastened into the screw-receiving portion  185   b  through the screw groove  149   d . The driver  180  may be fixed to the upper casing  120  by the fastening of the screw B 3 . 
     In one example, the screw groove  149   d  may be defined at the end of the upper plate  121  corresponding to the screw-receiving portion  185   b , thereby facilitating fastening and separating of the screw  83  to and from the screw-receiving portion  185   b.    
     Hereinafter, the ice-full state detection lever  700  will be described with reference to the drawings. 
       FIG.  56    is a side view of an ice-full state detection lever positioned at a topmost position, which is an initial position, according to an embodiment of the present disclosure. Further,  FIG.  57    is a side view of an ice-full state detection lever positioned at a bottommost position, which is a detection position. 
     As shown in  FIG.  56    and  FIG.  57   , the ice-full state detection lever  700  may be connected to the driver  180  and may be pivoted by the driver  180 . Further, the ice-full state detection lever  700  may pivot together when the lower assembly  200  pivots for the ice-removal to detect whether the ice bin  102  is in the ice-full state. In another example, the ice-full state detection lever  700  may be operated independently of the lower assembly  200  if necessary. 
     The ice-full state detection lever  700  has a shape bent in one direction (toward the left side of  FIG.  56   ) due to the first bent portion  721  and the second bent portion  722 . Therefore, even when the ice-full state detection lever  700  pivots as shown in  FIG.  57    to detect the ice-full state, the ice-full state detection lever  700  may effectively detect whether the ice stored in the ice bin  102  has reached the predefined vertical level without interfering with other components. The lower assembly  200  and the ice-full state detection lever  700  may pivot counterclockwise at a degree greater than a degree as shown  FIG.  57   . In one example, the lower assembly  200  and the ice-full state detection lever  700  may pivot by about 140° for effective ice-removal. 
     A length L 1  of the ice-full state detection lever  700  may be defined as the vertical distance from the rotation shaft of the ice-full state detection lever  700  to the detection body  710 . Further, the length of the ice-full state detection lever  700  may be larger than the distance L 2  of the bottom branch of the lower assembly  200 . If the length L 1  of the ice-full state detection lever  700  is smaller than the distance L 2  of the end branch of the lower assembly  200 , the ice-full state detection lever  700  and the lower assembly  200  may interfere with each other in the process in which the ice-full state detection lever  700  and the lower assembly  200  pivot. 
     To the contrary, if the ice-full state detection lever  700  is too long and when the lever  799  extends to the location of the ice I placed at the bottom of the ice bin  102 , there is a high probability of false detection. The ice made in this embodiment may be spherical and thus may roll and move inside the ice bin. Therefore, if the length of the ice-full state detection lever  700  is long enough to detect ice at the bottom of the ice bin  102 , there is a possibility of misdetection of the ice-full state due to the detection of the rolling ice even though the ice bin is not in an actual ice-full state. 
     Therefore, the ice-full state detection lever  700  may extend to a position higher by the diameter of the ice so that the lever may not detect the ice laid in one layer on the bottom of the ice bin  102 . In one example, the ice-full state detection lever  700  may extend to reach a position higher than the height L 5  by the diameter of the ice I from the bottom of the ice bin  102  upon the ice-full state detection. 
     That is, the ice may be stored at the bottom face of the ice bin  102 . Before the ice I entirely fills the first layer, the ice-full state detection lever  700  will not detect the ice-full state even when the lever pivots. When the refrigerator continues the ice-making and ice-removal processes, the ice spreads widely on the bottom face of the ice bin  102  instead of accumulating on the bottom of the ice bin  102  due to the characteristics of the spherical ice that is removed into the ice bin and thus sequentially forms an ice stack of multiple layers on the bottom face of the ice bin. Further, during the pivoting process of the lower assembly  200  or the movement process of the freezing compartment drawer  41 , the first layer ice I inside the ice bin  102  rolls to fill an empty space therein. 
     Once the first layer on the bottom of the ice bin  102  is fully filled with the ice, the removed ice may be stacked on top of the ice I of the first layer. In this connection, the vertical dimension of the ice in the second layer is not twice the diameter of the ice, but may be a sum of the diameter of an single ice and about ½ to ¾ of the diameter of the ice. This is because the ice of the second layer is settled into a valley formed between the ices of the first layer. 
     In one example, when the ice-full state detection lever  700  detects the ice portion just above the height L 5  of the ice I of the first layer, the detection may be erroneous when the ice height of the first layer is increased due to ice debris, etc. Thus, it would be desirable for the lever  700  to detect the ice portion higher than the height L 5  of the ice I of the first layer by a predefined distance. 
     Thus, the ice-full state detection lever  700  may be formed to extend to any point which is higher than the height L 5  by the diameter of the ice and is lower than the height L 6  which is a sum of the ½ to 4/3 of the diameter of the single ice and the diameter of the single ice. 
     In one example, the ice-full state detection lever  700  is short as possible as as long as it does not interfere with the lower tray  250 , thereby to secure the ice making amount. To prevent the erroneous detection due to the height difference caused by residual debris ices, the ice-full state detection lever  700  may have a length such that it extends to the top of the distance range L 6 . The top level of the vertical dimension L 6  may be equal to a sum of the ½ to 4/3 of the diameter of the single ice and the diameter of the single ice. 
     In this embodiment, an example in which the lever  799  detects the ice of the second layer is described. In a refrigerator having the ice bin  102  being a large vertical dimension and having an large amounts of spherical ices stored in the ice bin  102 , the lever  700  may detect the ice of the third layer or the ice of a higher layer. In this case, the ice-full state detection lever  700  may extend to a vertical level equal to a sum of the  1 / 2  to  4 / 3  of the diameter of the single ice and the diameters of the n ices from the bottom of the ice bin. 
     Hereinafter, the lower ejector  400  will be described with reference to the drawings. 
       FIG.  58    is an exploded perspective view showing a coupling structure of an upper casing and a lower ejector according to an embodiment of the present disclosure. Further,  FIG.  59    is a partial perspective view showing a detailed structure of a lower ejector. Further,  FIG.  60    shows a deformed state of a lower tray when the lower assembly fully pivots. Further,  FIG.  61    shows a state just before a lower ejector passes through a lower tray. 
     As shown in  FIG.  58    to  FIG.  61   , the lower ejector  400  may be mounted onto the side wall  143 . An ejector mounted portion  441  may be formed at the bottom of the side wall  143 . The ejector mounted portion  441  may be positioned to face the lower assembly  200  when the lower assembly  200  pivots. The ejector mounted portion  441  may be recessed into a shape corresponding to the shape of the lower ejector  400 . 
     A pair of body fixing portions  443  may protrude from the top face of the ejector mounted portion  441 . The body fixing portion  443  may have a hole  443   a  into which the screw is fastened. Further, the lateral portion  442  may be formed on each of both sides of the ejector mounted portion  441 . The lateral portion  442  may have a groove defined therein for receiving each of both ends of the lower ejector  400  so that the lower ejector  400  may be inserted in a slidable manner. 
     The lower ejector  400  may include a lower ejector body  410  fixed to the ejector mounted portion  441 , and a lower ejecting pin  420  protruding from the lower ejector body  410 . 
     The lower ejector body  410  may be formed into a shape corresponding to a shape of the ejector mounted portion  441 . The face defined by the lower ejecting pin  420  may be inclined so that the lower ejecting pin  420  faces toward the lower opening  274  when the lower assembly  200  pivots. 
     The top face of the lower ejector body  410  may have a body groove  413  defined therein for receiving the body fixing portion  443 . In the body groove  413 , a hole  412  to which the screw is fastened may be defined. Further, an inclined groove  411  may be recessed in the inclined face of the lower ejector body  410  corresponding to the hole  412  to facilitate the fastening and detachment of the screw. 
     Further, a guide rib  414  may protrude on each of the both sides of the lower ejector body  410 . The guide rib  414  may be inserted into the lateral portion  442  of the ejector mounted portion  441  upon mounting of the lower ejector  400 . 
     In one example, the lower ejecting pin  420  may be formed on the inclined face of the ejector body  310 . The number of the lower ejecting pins  420  may be equal to the number of the lower chambers  252 . The lower ejecting pins  420  may push the lower chambers  252  respectively for ice removal. 
     The lower ejecting pin  420  may include a rod  421  and a head  422 . The rod  421  may support the head  422 . Further, the rod  421  may be formed to have a predetermined length and slope or roundness such that the lower ejecting pin  420  extends to the lower opening  274 . The head  422  is formed at the extended end of the rod  421  and pushes the curved outer surface of the lower chamber  252  for the ice-removal. 
     In detail, the rod  421  may be formed to have a predetermined length. In one example, the rod  421  may extend such that the end of the head  422  meets an extension L 4  of the top of the lower chamber  252  when the lower assembly  200  fully pivots for the ice-removal. That is, the rod  421  may extend to a sufficient length so that when the head  422  pushes the lower tray  250  for the removal of the ice from the lower chamber  252 , the ice is pushed by the head  422  until the ice may deviate from at least the hemisphere area so that ice may be separated from the lower chamber  252 . 
     If the rod  421  is further longer, interference may occur between the lower opening  274  and the rod  421  when the lower assembly  200  pivots. If the rod  421  is too short, the removal the of ice from the lower tray  250  may not be carried out smoothly. 
     The rod  421  protrudes from the inclined surface of the lower ejector body  410  and has a predetermined inclination or roundness. The rod  421  may be configured to naturally pass through the lower opening  274  when the lower assembly  200  pivots. That is, the rod  421  may extend along the pivoting path of the lower opening  274 . 
     In one example, the head  422  may protrude from the end of the rod  421 . The head  422  may have a hollow  425  formed therein. Thus, the area of contact thereof with the ice surface may be increased such that the head  422  may push the ice effectively. 
     The head  422  may include an upper head 423  and a lower head  424  formed along the perimeter of the head  422 . The upper head 423  may protrude more than the lower head  424 . Therefore, the head  422  may effectively push the curved surface of the lower chamber  252  where the ice is accommodated, that is, push the convex portion  251   b . When the head  422  pushes the convex portion  251   b , both the upper head  423  and the lower head  424  are in contact with the curved face, thereby to push more reliably the ice for the ice-removal. 
     Thus, the spherical ice may be removed more effectively from the lower tray  250 . In one example, when the upper head 423  of the head  422  protrudes more than the lower head  424 , the lower opening  274  and the end of the upper head 423  may interfere with each other in the pivoting process of the lower assembly  200 . 
     In order to prevent the interference, the protruding length of the upper head  423  may be maintained, but the top face of the upper head  423  may be formed in an obliquely cut off shape. That is, the upper head  423  may have the top face as inclined. In this connection, the inclination of the upper head  423  may be configured such that the vertical level may gradually be lower toward the extended end of the upper head  423 . In order to form the cutoff portion of the upper head  423 , the top face portion of the upper head  423  may be partially cut off by an area where interference thereof with the lower opening occurs, that is, by approximately C. 
     Thus, as shown in  FIG.  61   , the upper head  423  may extend to a sufficient length to effectively contact the curved surface, but may not interfere with the perimeter of the lower opening  274  due to the presence of the cut off portion. That is, the rod  421  may have a sufficient length while the head  422  may be constructed to improve the contact ability with the curved surface and at the same time prevent the interference with the lower opening  274 , so that the ice-removal from the lower chamber  252  may be facilitated efficiently. 
     Hereinafter, the operation of the ice maker  100  will be described with reference to the drawings. 
       FIG.  62    is a cutaway view taken along a line  62 - 62 ′ of  FIG.  8   .  FIG.  63    is a view showing a state in which the ice generation is completed in  FIG.  62   . 
     Referring to  FIG.  62    and  FIG.  63   , the lower support  270  may be equipped with a lower heater  296 . 
     The lower heater  296  applies heat to the ice chamber  111  in the ice-making process, causing a top portion of water in the ice chamber  111  to be first frozen. Further, as the lower heater  296  periodically turns on and off in the ice-making process to generate heat. Thus, in the ice-making process, bubbles in the ice chamber  111  are moved downward. Thus, when the ice-making process is completed, a portion of the spherical ice except for the lowest portion may become transparent. That is, according to this embodiment, a substantially transparent spherical ice may be produced. In the present embodiment, the substantially transparent sphere shaped ice is not perfectly transparent but has a degree of transparency at which the ice may be commonly referred to as transparent ice. The substantially sphere shape is not a perfect sphere, but means a roughly spherically shape. 
     In one example, the lower heater  296  may be a wire type heater. The lower heater  296  may be a DC heater, like the upper heater  148 . The lower heater  296  may be configured to have a lower output than that of the upper heater  148 . In one example, the upper heater  148  may have a heat capacity of  9 . 5  W, while the lower heater  296  may have a  6 . 0 W heat capacity. Thus, the upper heater  148  and lower heater  296  may maintain the condition at which the transparent ice is made by heating the upper tray  150  and the lower tray  250  periodically at low heat capacity. 
     The lower heater  296  may contact the lower tray  250  to apply heat to the lower chamber  252 . In one example, the lower heater  296  may be in contact with the lower tray body  251 . 
     In one example, the ice chamber  111  is defined as the upper tray  150  and the lower tray  250  are arranged vertically and contact each other. Further, a top face  251   e  of the lower tray body  251  is in contact with a bottom face  151   a  of the upper tray body  151 . 
     In this connection, while the top face of the lower tray body  251  and the bottom face of the upper tray body  151  are in contact with each other, the elastic force of the elastic member  360  is exerted to the lower support  270 . The elastic force of the elastic member  360  is then applied to the lower tray  250  via the lower support  270  such that the top face  251   e  of the lower tray body  251  presses the bottom face  151   a  of the upper tray body  151 . Thus, while the top face of the lower tray body  251  is in contact with the bottom face of the upper tray body  151 , the both faces are pressed against each other, thereby improving adhesion therebetween. 
     Thus, when the adhesion between the top face of the lower tray body  251  and the bottom face of the upper tray body  151  is increased, there may be no gap between the two faces to prevent formation of a thin strip shaped burr around the spherical ice after the completion of the ice-making process. Further, as in  FIGS.  39  and  40   , the upper rib  153   d  and the lower rib  253   a  may prevent the gap formation until the ice-making process is completed. 
     The lower tray body  251  may further include the convex portion  25  lb in which the lower portion of the body  251  is convex upward. That is, the convex portion  251   b  may be configured to be convex toward the inside of the ice chamber  111 . 
     A convex shaped recess  251   c  may be formed below and in a corresponding manner to the convex portion  251   b  such that a thickness of the convex portion  251   b  is substantially equal to a thickness of the remaining portion of the lower tray body  251 . 
     As used herein, the phrase “substantially equal” may mean being exactly equal to each other or being equal to each other within a tolerable difference. 
     The convex portion  251  b may be configured to face the lower opening  274  of the lower support  270  in the vertical direction. 
     Further, the lower opening  274  may be located vertically below the lower chamber  252 . That is, the lower opening  274  may be located vertically below the convex portion  251   b.    
     As shown in  FIG.  62   , a diameter D 3  of the convex portion  251   b  may be smaller than a diameter D 4  of the lower opening  274 . 
     When cold-air is supplied to the ice chamber  111  while water has been supplied to the ice chamber  111 , the liquid water changes to solid ice. In this connection, the water expands in a process in which the water changes to the ice, such that a water expansion force is applied to each of the upper tray body  151  and the lower tray body  25 . 
     In this embodiment, while a portion (hereinafter, referred to as a corresponding portion) corresponding to the lower opening  274  of the support body  271  is not surrounded by the support body  271 , a remaining portion of the lower tray body  251  is surrounded by the support body  271 . 
     When the lower tray body  251  is formed in a perfect hemispherical shape, and when the expansion force of the water is applied to the corresponding portion of the lower tray body  251  corresponding to the lower opening  274 , the corresponding portion of the lower tray body  251  is deformed toward the lower opening  274 . 
     In this case, before the ice is produced, the water supplied to the ice chamber  111  is in a form of a sphere. However, after the ice has been produced, the deformation of the corresponding portion of the lower tray body  251  may allow an additional ice portion in a form of a protrusion to be formed to occupy a space created by the deformation of the corresponding portion. 
     Therefore, in this embodiment, the convex portion  25  lb may be formed in the lower tray body  251  in consideration of the deformation of the lower tray body  251  such that the shape of the finally created ice is identical as possible as with the perfect sphere. 
     In this embodiment, the water supplied to the ice chamber  111  does not have a spherical shape until the ice is formed. However, after the ice generation is completed, the convex portion  251  b of the lower tray body  251  is deformed toward the lower opening  274  such that the spherical ice may be generated. 
     In the present embodiment, since the diameter D 1  of the convex portion  251   b  is smaller than the diameter D 2  of the lower opening  274 , the convex portion  251   b  may be deformed and invade inside the lower opening  274 . 
     Hereinafter, an ice manufacturing process by an ice maker according to an embodiment of the present disclosure will be described.  FIG.  64    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    in a water-supplied state. Further,  FIG.  65    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    in an ice-making process. Further,  FIG.  66    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    in a state in which the ice-making process is completed. Further,  FIG.  67    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    at an initial ice-removal state. Further,  FIG.  68    is a cross-sectional view taken along a line  62 - 62 ′ of  FIG.  8    in a state in which an ice-removal process is completed. 
     Referring to  FIG.  64    to  FIG.  68   , first, the lower assembly  200  is moved to the water-supplied position. 
     In the water-supplied position of the lower assembly  200 , the top face  251   e  of the lower tray  250  is spaced apart from at least a portion of the bottom face  151   e  of the upper tray  150 . In the present embodiment, a direction in which the lower assembly  200  pivots for the ice-removal is referred to as a forward direction (a counterclockwise direction in the drawing), while a direction opposite to the forward direction is referred to as a reverse direction (a clockwise direction in the drawing). 
     In one example, an angle between the top face  251   e  of the lower tray  250  and the bottom face  151   e  of the upper tray  150  in the water-suppled position of the lower assembly  200  may be approximately 8°. However, the present disclosure may not be limited thereto. 
     In the water-supply position of the lower assembly  200 , the detection body  710  is located below the lower assembly  200 . 
     In this state, water is supplied by the water supply  190  to the ice chamber  111 . In this connection, water is supplied to the ice chamber  111  through one ejector-receiving opening of the plurality of ejector-receiving openings  154  of the upper tray  150 . 
     When the water supply is completed, a portion of the water as supplied may fill an entirety of the lower chamber  252 , while a remaining portion of the water as supplied may fill a space between the upper tray  150  and the lower tray  250 . 
     In one example, a volume of the upper chamber  151  and a volume of the space between the upper tray  150  and the lower tray  250  may be equal to each other. Then, water between the upper tray  150  and the lower tray  250  may fill an entirety of the upper tray  150 . Alternatively, the volume of the space between the upper tray  150  and the lower tray  250  may be smaller than the volume of the upper chamber  151 . In this case, the water may be present in the upper chamber  151 . 
     In the present embodiment, there is no channel for mutual communication between the three lower chambers  252  in the lower tray  250 . 
     Even when there is no channel for water movement in the lower tray  250 , a following result may be achieved because the lower tray  250  and the upper tray  150  are spaced apart from each other in the water-supply step as shown in  FIG.  64   : in the water-supply process, when a specific lower chamber  252  is fully filled with water, the water may move to neighboring lower chambers  252  to fill all of the lower chambers  252 . Thus, each of the plurality of lower chambers  252  of the lower tray  250  may be fully filled with water. 
     Further, in this embodiment, since there is no channel for communication between the lower chambers  252  in the lower tray  250 , the presence of the additional ice portion in the form of the protrusion around the ice after the ice has been created may be suppressed. 
     When the water-supply is completed, the lower assembly  200  pivots in the reverse direction as shown in  FIG.  30   . When the lower assembly  200  pivots in the reverse direction, the top face  251   e  of the lower tray  250  is brought to be close to the bottom face  151   e  of the upper tray  150 . 
     Then, water between the top face  251   e  of the lower tray  250  and the bottom face  151   e  of the upper tray  150  is divided into portions which in turn are distributed into the plurality of upper chambers  152  respectively. Further, when the top face  251   e  of the lower tray  250  and the bottom face  151   e  of the upper tray  150  come into a close contact state with each other, the upper chambers  152  may be filled with water. 
     In one example, when the lower assembly is in a closed state such that the upper tray  150  and lower tray  250  are in close contact with each other, the chamber wall  153  of the upper tray body  151  may be accommodated in the interior space of the side wall  260  of the lower tray  250 . 
     In this connection, the vertical wall  153   a  of the upper tray  150  may face the vertical wall  260   a  of the lower tray  250 , while the curved wall  153   b  of the upper tray  150  may face the curved wall  260   b  of the lower tray  250 . 
     The outer face of the chamber wall  153  of the upper tray body  151  is spaced apart from the inner face of the side wall  260  of the lower tray  250 . That is, a space (G 2  in  FIG.  39   ) is formed between the outer face of the chamber wall  153  of the upper tray body  151  and the inner face of the side wall  260  of the lower tray  250 . 
     The water supplied from the water supply  180  may be supplied while the lower assembly  200  pivots at a predetermined angle to be open such that the water fill the entire ice chamber  111 . Thus, the water as supplied will fill the lower chamber  252  and fill an entirety of the inner space defined with the side wall  260 , thereby to fill the neighboring lower chambers  252 . In this state, when the water supply to the predefined level is completed, the lower assembly  200  pivots to be closed so that the water level in the ice chamber  111  becomes the predefined level. In this connection, the space (G 1 , G 2 ) between the inner faces of the side wall  260  of the lower tray  250  is inevitably filled with water. 
     In one example, when more than a predefined amount of water in the water-supply process or ice-making process is supplied to the ice chamber  111 , the water from the ice chamber  111  may flow into the ejector-receiving opening  154 , that is, into the buffer. Thus, even when more than the predefined amount of water is present in the ice chamber  111 , the water may be prevented from overflowing the ice maker  100 . 
     For this reason, while the top face of the lower tray body  251  contacts the bottom face of the upper tray body  151  such that the lower assembly is in a closed state, the top of the side wall  260  may be positioned at a higher level than the bottom of the ejector-receiving opening  154  of the upper tray  150  or the top of the upper chamber  152 . 
     The position of the lower assembly  200  while the top face  251   e  of the lower tray  250  and the bottom face  151   e  of the upper tray  150  contact each other may be referred to as the ice-making position. In the ice-making position of the lower assembly  200 , the detection body  710  is positioned below the lower assembly  200 . 
     Then, the ice-making process begins while the lower assembly  200  has moved to the ice-making position. 
     During the ice-making process, the pressure of the water is lower than the force for deforming the convex portion  251   b  of the lower tray  250 , so that the convex portion  251   b  remains undeformed. 
     When the ice-making process begins, the lower heater  296  may be turned on. When the lower heater  296  is turned on, heat from the lower heater  296  is transferred to the lower tray  250 . 
     Thus, when the ice-making is performed while the lower heater  296  is turned on, a top portion of the water the ice chamber  111  is first frozen. 
     In this embodiment, a mass or volume the water in the ice chamber  111  may vary or may not vary along a height of the ice chamber depending on the shape of the ice chamber  111 . 
     For example, when the ice chamber  111  has a cuboid shape, the mass or volume of the water in the ice chamber  111  may not vary along the height thereof. 
     To the contrary, when the ice chamber  111  has a sphere, an inverted triangle or a crescent shape, the mass or volume may vary along the height thereof. 
     When the temperature of the cold-air and the amount of the cold-air supplied to the freezing compartment  4  are constant, and when the output of the lower heater  296  is constant, a rate at which the ice is produced may vary along the height when the ice chamber  111  has a sphere, an inverted triangle or a crescent shape such that the mass or volume may vary along the height thereof. 
     For example, when the mass per unit height of water is small, ice formation rate is high, whereas when the mass per unit height of water is large, ice formation rate is low. 
     As a result, the rate at which ice is generated along the height of the ice chamber is not constant, such that the transparency of the ice may vary along the height. In particular, when ice is generated at a high rate, bubbles may not move from the ice to the water, such that ice may contain bubbles, thereby lowering the ice transparency. 
     Therefore, in this embodiment, the output of the lower heater  296  may be controlled based on the mass per unit height of water of the ice chamber  111 . 
     When the ice chamber  111  is formed into a spherical shape, as shown in this embodiment, the mass per unit height of water in the ice chamber  111  increases in a range from a top to a middle level and then decreases in a range from the middle level to the bottom. 
     Thus, after the lower heater  296  turns on, the output of the lower heater  430  decreases gradually and then the output is minimal at the middle level of the chamber. Then, the output of the lower heater  296  may increase gradually from the middle level to the top of the chamber. 
     Thus, since the top portion of the water in the ice chamber  111  is first frozen, bubbles in the ice chamber  111  move downwards. In the process where ice is generated in a downward direction in the ice chamber  111 , the ice comes into contact with the top face of the convex portion  251   b  of the lower tray  250 . 
     When the ice is continuously generated in this state, the convex portion  25  lb is deformed by the ice pressing the convex portion as shown in  FIG.  31   . When the ice-making process is completed, the spherical ice may be generated. 
     A controller (not shown) may determine whether the ice-making is completed based on the temperature detected by the temperature sensor  500 . 
     The lower heater  296  may be turned off when the ice-making is completed or before ice-making is completed. 
     When the ice-making process is completed, the upper heater  148  may first be turned on for ice-removal of the ice. When the upper heater  148  is turned on, the heat from the upper heater  148  is transferred to the upper tray  150 , thereby to cause the ice to be separated from the inner face of the upper tray  150 . 
     After the upper heater  148  is activated for a predefined time, the upper heater  148  is turned off. Then, the driver  180  may be activated to pivot the lower assembly  200  in the forward direction. 
     As the lower assembly  200  pivot in a forward direction, as shown in  FIG.  66   , the lower tray  250  is spaced apart from the upper tray  150 . 
     Further, the pivoting force of the lower assembly  200  is transmitted to the upper ejector  300  via the connector  350 . Then, the upper ejector  300  is lowered by the unit guides  181  and  182 , such that the ejecting pin  320  is inserted into the upper chamber  152  through the ejector-receiving opening  154 . 
     In the ice-removal process, the ice may be removed from the upper tray  250  before the ejecting pin  320  presses the ice. That is, the ice may be separated from the surface of the upper tray  150  due to the heat of the upper heater  148 . 
     In this case, the ice may be moved together with the lower assembly  200  while the ice is supported by the lower tray  250 . 
     Alternatively, the ice does not separate from the surface of the upper tray  150  even though the heat of the upper heater  148  is applied to the upper tray  150 . 
     Thus, when the lower assembly  200  pivots in a forward direction, the ice may be separated from the lower tray  250  while the ice is in close contact with the upper tray  150 . 
     In this state, in the pivoting process of the lower assembly  200 , the ice may be released from the upper tray  150  when the ejecting pin  320  passes through the ejector-receiving opening  154  and then presses the ice as is in close contact to the upper tray  150 . The ice removed from the upper tray  150  may again be supported by the lower tray  250 . 
     When the ice moves together with the lower assembly  200  while the ice is supported by the lower tray  250 , the ice may be separated from the lower tray  250  by its own weight even when no external force is applied to the lower tray  250 . 
     In the forward pivoting process of the lower assembly  200 , the ice-full state detection lever  700  may move to the ice-full state detection position, as shown in  FIG.  67   . In this connection, when the ice bin  102  is in the ice-full state, the ice-full state detection lever  700  may move to the ice-full state detection position. 
     While the ice-full state detection lever  700  has moved to the ice-full state detection position, the detection body  700  is located below the lower assembly  200 . 
     When, in the pivoting process of the lower assembly  200 , the ice is not separated, via the weight thereof, from the lower tray  250 , the ice may be removed from the lower tray  250  when the lower tray  250  is pressed by the lower ejector  400  as shown in  FIG.  68   . 
     Specifically, in the process in which the lower assembly  200  pivots, the lower tray  250  comes into contact with the lower ejecting pin  420 . 
     Further, as the lower assembly  200  continues to pivot in the forward direction, the lower ejecting pin  420  will pressurize the lower tray  250 , thereby deforming the lower tray  250 . Thus, the pressing force of the lower ejecting pin  420  may be transferred to the ice, thereby causing the ice to be separated from the surface of the lower tray  250 . Then, the ice separated from the surface of the lower tray  250  may fall downward and be stored in the ice bin  102 . 
     After the ice is removed from the lower tray  250 , the lower assembly  200  may pivot in the reverse direction by the driver  180 . 
     When the lower ejecting pin  420  is spaced apart from the lower tray  250  in the process in which the lower assembly  200  pivots in the reverse direction, the deformed lower tray may be restored to its original form. 
     Further, in the reverse pivoting process of the lower assembly  200 , the pivoting force is transmitted to the upper ejector  300  via the connector  350 , thereby causing the upper ejector  300  to rise up. Then, the ejecting pin  320  is released from the upper chamber  152 . 
     Further, the driver  180  will stop when the lower assembly  200  reaches the water-supplied position, and then the water supply begins again. 
     As described above, the present disclosure is described with reference to the drawings. However, the present disclosure is not limited by the embodiments and drawings disclosed in the present specification. It will be apparent that various modifications may be made thereto by those skilled in the art within the scope of the present disclosure. Furthermore, although the effect resulting from the features of the present disclosure has not been explicitly described in the description of the embodiments of the present disclosure, it is obvious that a predictable effect resulting from the features of the present disclosure should be recognized.