Patent Publication Number: US-2023138859-A1

Title: Cooking appliance

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application No. 10-2021-0146087, filed Oct. 28, 2021 and Application No. 10-2022-0001821, filed Jan. 5, 2022, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates generally to a cooking appliance including a heater vertically movable in a cooking chamber. 
     Description of the Related Art 
     A cooking appliance is provided to cook food accommodated therein by using heat of a heater provided as a heating source. 
     Generally, the cooking appliance includes a main body including a cooking chamber that is a space accommodating food therein, at least one heater provided in the main body, and a door rotatably coupled to the main body and closing and opening a front surface of the cooking chamber. 
     Recently, in order to increase the effectiveness of the cooking appliance, a steam generator as in Korean Patent Application Publication No. 10-2018-0126237 may be added to the cooking appliance. 
     Furthermore, in the food thawing device disclosed in US Patent No. US4303820, a pair of flat electrodes defining a food thawing zone is provided, and one of the pair of flat electrodes is provided to be movable for insertion of a frozen food rod. In addition, a relatively low wattage power supply device provides even energy distribution across the food load for smooth heating (thawing). 
     In the apparatus and method for reheating a package of refrigerated or frozen food disclosed in US Registration No. US8258440, the apparatus and method for reheating a package of refrigerated or frozen food are disclosed. In addition, the heating mechanism is in conductive heat transfer contact with the food package, and heats food to a reheat temperature, and is operated for a reheat time for reheating the food package, and then is maintained at the reheat temperature if desired. 
     However, a link-type elevating system has been disclosed in the conventional cooking appliance, but due to the structure such as the heater descending by its own weight for thawing food, ascending and descending of the heater are not precisely performed, and a crash prevention with respect to food in the cooking appliance or original position control of the heater is insufficient. Therefore, there is a risk of leakage of electromagnetic waves in the cooking appliance and occurrence of safety accidents and failure due to product damage. 
     Documents of Related Art 
     
         
         Korean Patent Application Publication No. 10-2018-0126237 
         U.S. Pat. No. US4303820 
         U.S. Pat. No. US8258440 
       
    
     SUMMARY OF THE INVENTION 
     Accordingly, the present disclosure has been made keeping in mind the above problems occurring in the related art, and the present disclosure is intended to provide a cooking appliance with a heater moving vertically intentionally in the cooking chamber. 
     Furthermore, another objective of the present disclosure is to provide a cooking appliance configured to efficiently shield electromagnetic waves through perimeter of a heater system that is raised and lowered. 
     Furthermore, a further objective of the present disclosure is to provide a cooking appliance configured to mechanically detect interference between a raised and lowered heater and food. 
     In order to achieve the above objectives, according to one aspect of the present disclosure, a cooking appliance according to the present disclosure includes a heater moving inside a cooking chamber. Therefore, cooking is possible with the heater moving closer to food. 
     In the present disclosure, a system may be provided in the cooking appliance allowing the heater to be movable inside the cooking chamber. 
     In the present disclosure, a detection function of detecting a contact status of the heater to the food or the amount of approaching of the heater to the food may be provided. 
     In the present disclosure, a detection function of controlling the heater so that the moving heater is recovered to the original position thereof or whether or not the moving heater is recovered to a regular position thereof may be provided. 
     In addition, according to the present disclosure, the cooking appliance may include a casing in which the cooking chamber is provided, a door rotatably provided at one portion of the casing and opening and closing the cooking chamber, a movable heater system including the heater emitting heat and allowing the heater to be movable inside the cooking chamber, a contact detection means detecting whether or not the heater is brought into contact with food inside the cooking chamber or is spaced a predetermined distance, and an original position detection means detecting whether or not the heater is recovered to the original position thereof. 
     Furthermore, according to the present disclosure, the cooking appliance may include the casing in which the cooking chamber is provided, the door opening and closing the cooking chamber, and the movable heater system provided at one portion of the casing and allowing the heater to be movable inside the cooking chamber. 
     According to the present disclosure, the cooking appliance may include the casing in which the cooking chamber is provided, the door opening and closing the cooking chamber, a moving assembly provided to be vertically movable inside the cooking chamber and including the heater, and the contact detection means detecting whether or not the moving assembly is brought into contact with an object inside the cooking chamber when the moving assembly is lowered. 
     According to the present disclosure, the cooking appliance may include the casing in which the cooking chamber is provided, the door opening and closing the cooking chamber, the heater emitting heat, the movable heater system allowing the heater to be movable inside the cooking chamber, and the original position detection means detecting whether or not the heater is located at the original position. 
     The movable heater system may include: the moving assembly to which the heater is mounted and protected and a fixed assembly provided one portion of the casing and controlling vertical movement of the moving assembly; and a link assembly provided at one portion of the moving assembly, and movably connecting the moving assembly to the fixed assembly. 
     The fixed assembly may include a moving control means restraining the moving assembly to move vertically by control of the link assembly. 
     The moving control means may include a motor generating rotation power, a lead screw provided at one portion of the motor and rotated in conjunction with rotation generated by the motor, and a lead nut fastened to the lead screw by screwing. 
     A connection coupling may be provided between the motor and the lead screw, and the connection coupling may connect a first end of the lead screw to a motor shaft. 
     The motor may be provided at a fixed bracket securely mounted to the fixed assembly, and the lead nut may be mounted to a moving bracket movably provided to the fixed assembly. 
     The fixed assembly may include a sliding rail slidingly supporting the moving bracket. 
     The fixed assembly may include: an upper plate providing an upper surface of the cooking chamber; a protection cover provided at the upper plate and shielding electromagnetic waves through a gap between the moving assembly and the fixed assembly; and a fixed frame provided above the upper plate and supporting the moving control means. 
     The fixed frame may be provided above the upper plate to be spaced apart therefrom by a fixed guide. 
     A gap of a predetermined size may be provided between the fixed frame and the protection cover. 
     The sliding rail may be securely provided on the upper surface of the fixed frame, and the sliding rail may include a sliding member slidingly provided and supporting the moving bracket. 
     A plurality of guide members may be provided at the protection cover, and the plurality of guide members may guide vertical movement of the moving assembly. 
     The moving assembly may include a heater housing covering and protecting the heater and an insulating member provided one end of the heater housing and shielding heat or electromagnetic waves. 
     The heater housing may have a rectangular box shape, and at least one heater hole through which heat of the heater may pass may be formed on a bottom surface thereof by being vertically perforated. 
     The heater housing may pass through the gap between the fixed frame and the protection cover and move vertically. 
     The link assembly may have a structure including at least one link, and an upper end thereof may be rotatably connected to the fixed assembly, and a lower end thereof may be rotatably connected to the moving assembly. 
     The link assembly may include a pair of front links and a pair of rear links, and the pair of front links may be provided to be spaced apart from the pair of rear links at a predetermined distance forward and rearward. 
     A link frame may be provided below lower ends of the front links and the rear links, the link frame being coupled to the moving assembly. 
     At least one of left and right lower ends of each of the front links and the rear links may be movable while being coupled to the link frame. 
     The original position detection means and the contact detection means may be provided at one portion of the fixed assembly, and the original position detection means may detect the original position of the moving assembly and the contact detection means may detect whether or not a lower end of the moving assembly is brought into contact with the food inside the cooking chamber. 
     The cooking appliance according to the present disclosure has the following effects. 
     First, the cooking appliance according to the present disclosure is configured to allow the heater to move vertically inside the cooking chamber. Therefore, food is cooked with the heater moving closer to the food in the cooking chamber, so that it is possible to minimize heat loss and reduce a cooking time of food. 
     Second, in the present disclosure, the flexible connection coupling is provided between the motor and the lead screw. Therefore, it is possible to reduce power loss due to a concentricity error between the motor shaft and the lead screw and to facilitate transmission of rotation power. 
     Third, in the present disclosure, the guide members are provided to guide the vertical movement of the moving assembly. In other words, the plurality of roller-type guide members is provided to control the vertical movement of the moving assembly. Therefore, when the moving assembly with the heater moves vertically, it is possible to prevent interference of the heater housing, the protection cover, and the fixed frame and prevent damage to parts thereof and occurrence of noise. 
     Fourth, in the present disclosure, the insulating member is provided in the moving assembly and shields the gap between the moving assembly and the casing of the cooking appliance. Therefore, it is possible to prevent the leakage of electromagnetic waves through the gap between the moving assembly and the casing. 
     Fifth, in the present disclosure, the edge of the insulating member provided in the moving assembly is overlapped with the upper plate providing the upper surface of the cooking chamber. Therefore, when the moving assembly is raised and located at the original position thereof in the cooking chamber, it is possible to prevent the leakage of electromagnetic waves in the cooking chamber to the outside space. 
     Sixth, in the present disclosure, the protection switch is provided to detect whether or not the moving assembly interferes with the food when the moving assembly is lowered. Therefore, when the food and the moving assembly are brought into contact with each other, lowering of the moving assembly stops, so that it is possible to prevent damage to the food and the parts thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view showing an inner structure of a cooking appliance according to an exemplary embodiment of the present disclosure, wherein the inner structure is shown without an outer cover. 
         FIG.  2    is a perspective view showing a structure of a movable heater system constituting the embodiment of the present disclosure. 
         FIG.  3    is an exploded-perspective view showing the movable heater system constituting the embodiment of the present disclosure. 
         FIG.  4    is a plane view showing the movable heater system shown in  FIG.  2   . 
         FIG.  5    is a front view showing the movable heater system shown in  FIG.  2   . 
         FIG.  6    is a side view showing the movable heater system shown in  FIG.  2   . 
         FIG.  7    is a front sectional view showing the movable heater system shown in  FIG.  2   . 
         FIG.  8    is a perspective view showing the movable heater system shown in  FIG.  2    with a heater lowered. 
         FIG.  9    is a plane view showing the movable heater system shown in  FIG.  8   . 
         FIG.  10    is a front view showing the movable heater system shown in  FIG.  8   . 
         FIG.  11    is a side view showing the movable heater system shown in  FIG.  8   . 
         FIG.  12    is an exploded-perspective view showing a structure of a fixed assembly constituting the movable heater system of the cooking appliance according to the present disclosure. 
         FIG.  13    is an exploded-perspective view showing a structure of a moving assembly constituting the movable heater system of the cooking appliance according to the present disclosure. 
         FIG.  14    is an exploded-perspective view showing a structure of a link assembly of the movable heater system of the cooking appliance according to the present disclosure. 
         FIG.  15    is an exploded-perspective view showing a structure of an upper plate, a protection cover, and a fixed frame constituting the embodiment of the present disclosure. 
         FIG.  16    is a perspective view showing a structure of a guide member constituting the embodiment of the present disclosure. 
         FIG.  17    is an exploded-perspective view showing a structure of a moving control means constituting the embodiment of the present disclosure. 
         FIG.  18    is a perspective view showing a fixed bracket constituting the embodiment of the present disclosure. 
         FIG.  19    is a perspective view showing a moving bracket constituting the embodiment of the present disclosure. 
         FIG.  20    is a perspective view showing a structure of a protection bracket constituting the embodiment of the present disclosure. 
         FIG.  21    is a perspective view showing a structure of a position bracket constituting the embodiment of the present disclosure. 
         FIG.  22    is an exploded-perspective view showing a structure of a heater housing and an insulating member constituting the embodiment of the present disclosure. 
         FIG.  23    is a perspective view showing a structure of a support end of the moving assembly constituting the embodiment of the present disclosure. 
         FIG.  24    is an exploded-perspective view showing a main structure of the link assembly constituting the embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, a cooking appliance according to the present disclosure will be described in detail with reference to accompanying drawings. The cooking appliance according to the present disclosure may be food cookers of various shapes such as a microwave, an electric oven, etc. 
       FIG.  1    is a perspective view showing the cooking appliance according to an embodiment of the present disclosure. In other words, in  FIG.  1   , to describe the cooking appliance according to the present disclosure, a main structure inside the cooking appliance with removing an outer cover will be shown as the perspective view. 
     As shown in the drawing, the cooking appliance according to the present disclosure includes a casing  10  in which a cooking chamber  12  is provided, and a door  20  provided at one portion of the casing  10  and opening and closing the cooking chamber  12 . 
     The casing  10  serves as a main body of the cooking appliance, and may be shaped in a rectangular box as shown in the drawing, and be preferably open at a front portion thereof so as to put in and take out food. 
     As described above, when the front portion of the casing  10  is open, the door  20  is provided for shielding the cooking chamber when cooking food, and the door  20  may be rotatably provided on a hinge so as to be able to open and close. 
     In the present disclosure, as shown in the drawing, the case in which the door  20  is rotatably provided on the hinge at a lower end is illustrated. 
     A front frame  14  is provided at a front surface of the casing  10  and provides the exterior shape of the front portion of the casing  10 , and various display parts (not shown) or deco panels may be provided thereto. 
     A support plate  30  may be provided in the cooking chamber  12  to support food or a container, and the support plate  30  may be rotatably provided. 
     A movable heater system  100  may be provided above the casing  10  as shown in the drawing. The movable heater system  100  is a system allowing a heater to move vertically in the cooking chamber  12 . 
     The heater may be provided above the casing  10  and emit heat, and at least two heaters may be provided. In other words, the movable heater system  100  may include the heater and the heater may move vertically in the cooking chamber  12 , and the heater may be additionally provided in the casing  10  in addition to the movable heater system  100 . 
     In addition, the cooking appliance according to the present disclosure may include a function of detecting whether or not the heater of the movable heater system  100  is brought into contact with food in the cooking chamber  12  or is spaced apart from the food at a predetermined distance and a function of detecting recovery of the heater of the movable heater system  100  to the original location thereof. 
     The movable heater system  100  as described above and various functions thereof will be described below. 
       FIGS.  2  to  14    are views showing the structure of the movable heater system  100 . In other words,  FIGS.  2  and  3    are a perspective view and an exploded-perspective view showing the structure of the movable heater system  100 .  FIGS.  4  to  7    are a plane view, a front view, a side view, and a front sectional view of the movable heater system  100 . Furthermore,  FIG.  8    is a perspective view showing the structure of the movable heater system  100  with the inner heater lowered.  FIGS.  9  to  11    are a plane view, a front view, and a side view showing the movable heater system  100  shown in  FIG.  8   .  FIGS.  12  to  14    are exploded-perspective views showing a fixed assembly, a moving assembly, and a link assembly that constitute the movable heater system  100 . 
     As shown in the drawings, the movable heater system  100  includes a heater  210  emitting heat, and the heater  210  may be provided to be vertically movable in the cooking chamber  12 . 
     Furthermore, the casing  10  or the movable heater system  100  may have a function of detecting whether or not the heater  210  is brought into contact with food inside the cooking chamber  12  or is spaced apart from the food at a predetermined distance and a function of detecting recovery of the heater  210  to the original position of the heater. 
     The movable heater system  100  may include a moving assembly  200  to which the heater  210  is mounted and protected, a fixed assembly  300  provided at one portion of the casing  10  and controlling a vertical movement of the moving assembly  200 , and a link assembly  400  provided at one portion of the moving assembly  200  and movably connecting the moving assembly  200  to the fixed assembly  300 . 
     The moving assembly  200  is separably provided from the casing  10  to be movable inside the cooking chamber  12 , and surrounds at least side portion of the heater  210  so that it is preferable that heat of the heater  210  is concentrated downward and is prevented from emitting sideways. 
     The fixed assembly  300  may be securely provided on the casing  10  and supports the moving assembly  200  so that the moving assembly  200  moves in a vertical direction while being supported by an upper surface of the casing  10 . 
     Therefore, the fixed assembly  300  includes a moving control means  500 , and the moving control means  500  restrains the moving assembly  200  so that the moving assembly  200  vertically moves by control of the link assembly  400 . 
     The link assembly  400  may be provided above, etc. the moving assembly  200 , and includes at least one link, thereby guiding the moving assembly  200  so that the moving assembly  200  moves vertically while being connected to the fixed assembly  300 . 
     Upper and lower ends of the link assembly  400  may be rotatably connected to the fixed assembly  300  and the moving assembly  200 , respectively. 
     The fixed assembly  300  may include an upper plate  310  providing an upper surface of the cooking chamber  12 , a protection cover  320  provided at the upper plate  310  and blocking electromagnetic waves via a gap between the moving assembly  200  and the fixed assembly  300 , and a fixed frame  330  provided above the upper plate  310  and supporting the moving control means  500 . 
     The upper plate  310  may be shaped in a rectangular plate having a predetermined thickness and provide the upper surface of the cooking chamber  12 . In addition, a center portion of the upper plate  310  may be vertically perforated and provide a path through which the moving assembly  200  moves vertically. 
     The fixed frame  330  may be provided to be spaced apart from the protection cover  320 . 
     More specifically, the protection cover  320  may also have a rectangular shape like the upper plate  310 , and a hole vertically perforated may be formed in a center portion of the protection cover  320  like the upper plate  310  and may have a rectangular frame shape. Therefore, the moving assembly  200  may move vertically via the center holes of the upper plate  310  and the protection cover  320 . 
     Then, the fixed frame  330  may have a rectangular shape smaller than the hole formed in the center portion of the protection cover  320 . Therefore, a predetermined gap is formed between the fixed frame  330  and the protection cover  320 , and it is preferable that a heater housing  220  of the moving assembly  200  is accommodated in the gap and moves vertically. 
     The fixed frame  330  may be securely provided above the upper plate  310 , and therefore, a fixed guide  340  may be provided between the upper plate  310  and the fixed frame  330 . 
     As shown in the drawing, the fixed guide  340  may have a shape of ‘ ∩ ‘ (when which is seen from the front side). Therefore, an upper end of the fixed guide  340  may be coupled to the fixed frame  330 , and a lower end thereof may be fixed to the upper plate  310  or the protection cover  320 . 
     Specifically, the fixed guide  340  may include a frame coupling part  342  coupled to the fixed frame  330 , and an upper coupling part  344  fixed to the upper plate  310  or the protection cover  320 . In the present disclosure, the case in which the upper coupling part  344 , i.e., the lower end of the fixed guide  340  is fastened to the upper surface of the upper plate  310  is illustrated. 
     A plurality of fixed guides  340  may be provided and, in the present disclosure, the case in which two fixed guides  340  are provided at an upper portion of the upper plate  310  to be spaced apart from each other forward and rearward at a predetermined gap and supports the fixed frame  330  is illustrated. 
     The fixed assembly  300  may include a sliding rail  350  slidingly supporting a moving bracket  560 , a lead nut  530 , or the like, and the moving bracket  560  and the lead nut  530  will be described below. 
     Specifically, the sliding rail  350  is provided at an upper surface of the fixed frame  330  to have a predetermined transversal length, and the moving bracket  560  or the lead nut  530 , which will be described below, may be provided on the sliding rail  350  to be movable left and right. 
     The moving control means  500  may be provided above the fixed frame  330 . 
     The moving control means  500  may include a motor  510  generating rotating power, a lead screw  520  provided at one portion of the motor  510  and rotated in conjunction with rotation generated by the motor  510 , and the lead nut  530  fastened to the lead screw  520  by screwing. 
     The motor  510  may generate rotation power, and a stepping motor may be used as the motor  510  so as to perform precise rotation control. The stepping motor may perform the supply of forward and reverse rotation movements in response to a rotation angle by pulse control. 
     As shown in the drawings, the lead screw  520  may be a fine cylinder of a predetermined length, of which an outer surface is formed in a male screw and, herein, the lead screw  520  may be fastened with the lead nut  530  having a female screw corresponding to the male screw of the lead screw  520 . Therefore, when the lead screw  520  is rotated by the power of the motor  510 , the lead nut  530  moves left and right along the lead screw  520 . As described above, the lead screw  520  and the lead nut  530  serves to change the forward/reverse rotation movements into a linear movement. 
     A connection coupling  540  may be provided between the motor  510  and the lead screw  520 , and the connection coupling  430  may connect one end of the lead screw  520  to the motor shaft. As shown in the drawings, the connection coupling  540  may be provided at a right end of the lead screw  520  and the motor shaft protruding leftward from the motor  510 . 
     The connection coupling  540  is used to reduce power loss due to a concentricity error between the shaft of the motor  510  and the shaft of the lead screw  520  and to make rotation smooth, and it is preferable that a flexible coupling is used as the connection coupling. In other words, as the connection coupling  540 , a MST-type or MSTS-type flexible coupling may be used. 
     The motor  510  may be provided at a fixed bracket  550  securely mounted to the fixed assembly  300 , and the lead nut  530  may be mounted to the moving bracket  560  movably installed to the fixed assembly  300 . 
     Specifically, the fixed frame  330  may be provided above the upper plate  310  to be spaced apart therefrom by the fixed guides  340 . A predetermined gap may be provided between the fixed frame  330  and the protection cover  320 , thereby providing a moving path of the heater housing  220 . 
     Furthermore, both of the fixed bracket  550  and the moving bracket  560  are provided above the fixed frame  330  of the fixed assembly  300 . As shown in the drawings, the fixed bracket  550  is securely mounted to the upper surface of the fixed frame  330 , and the moving bracket  560  is movably provided to move closer to or away from the fixed bracket  550  above the fixed frame  330 . 
     As described above, the sliding rail  350  is securely installed to the fixed frame  330 , and a sliding member  352  may be slidingly provided at the sliding rail  350  and support the moving bracket  560 . 
     As shown in the drawings, the sliding member  352  having a rectangular plate shape may be provided at an upper portion of the sliding rail  350  to be slidable left and right, and the moving bracket  560  may be fixed on an upper surface of the sliding member  352  and be movable left and right. 
     The motor  510  may be mounted to the fixed bracket  550  and the lead nut  530  may be mounted to the moving bracket  560 . Therefore, when the lead screw  520  is rotated in response to rotation of the motor  510  mounted to the fixed bracket  550 , the lead nut  530  moves left and right, and eventually, the moving bracket  560  moves left and right along the sliding rail  350 . 
     Link upper ends of the link assembly  400  may be rotatably installed to the fixed bracket  550  and the moving bracket  560 . In other words, when the left and right upper ends of the ‘X′-shaped link provided in the link assembly  400  are respectively connected to the fixed bracket  550  and the moving bracket  560 , left and right movement of the moving bracket  560  allows the left and right upper ends of the ‘X’-shaped link to move closer to or away from each other, so that the moving assembly  200  fixed to a lower end of the link assembly  400  moves up and down. 
     A protection bracket  360  and a position bracket  380  may be provided on the fixed frame  330  of the fixed assembly  300 . 
     As shown in the drawings, the protection bracket  360  may be provided on an upper surface of a left end of the fixed frame  330 , and a protection switch  370  may be installed thereto, and the protection switch  370  has the detection function for protecting the parts from interference of the heater  210  and food. 
     As shown in the drawings, the position bracket  380  may be provided at an upper surface of a right end of the fixed frame  330 , and a the position switch  390 , etc. may be installed thereto, and the position switch  390  allows the moving assembly  200  to be recovered to the original location thereof or detects that the moving assembly  200  is located at the original location. 
     The protection cover  320  may include a plurality of guide members  322  guiding vertical movement of the moving assembly  200 . As shown in the drawings, four guide members  322  may be respectively provided at four corners of the protection cover  320  of the rectangular frame shape, and the guide members  322  serve to support the heater housing  220  to prevent the heater housing  220  from interfering with the protection cover  320  when the heater housing  220  to be described below passes through the gap between the fixed frame  330  and the protection cover  320 . 
     The moving assembly  200  may include the heater housing  220  and an insulating member  230 , the heater housing  220  covering and protecting the heater  210  and the insulating member  230  being provided at one end of the heater housing  220  and blocking heat or electromagnetic waves. 
     The heater housing  220  may have a rectangular box shape as shown in the drawings, and a bottom surface thereof may have at least one hole, which is formed by being vertically perforated, so as to allow the passage of heat of the heater  210 . 
     The heater housing  220  may move up and down by passing through the gap between the fixed frame  330  and the protection cover  320 . Therefore, the heater housing  220  may have the rectangular box shape with an open upper portion, and have a predetermined thickness. Thicknesses of the four lateral surfaces of the heater housing  220  may be preferably formed smaller than the size of the gap between the fixed frame  330  and the protection cover  320 . 
     The heater housing  220  may have guide grooves  222  selectively storing the fixed guide  340 . In other words, as shown in the drawings, the guide grooves  222  may be formed in the left and right lateral surfaces of the heater housing  220  by being depressed downward from upper ends of the surfaces at a predetermined length. The frame coupling part  342  of the fixed guide  340  is stored in the guide grooves  222  when the moving assembly  200  is raised. 
     The insulating member  230  may be preferably formed to have a rectangular frame shape as shown in the drawings, and lateral ends thereof may be preferably formed to protrude outward than lateral ends of the heater housing  220 . The exterior size of the insulating member  230  may be formed larger than the lateral size of the heater housing  220 , so that the insulating member  230  may serve to shield electromagnetic waves from leaking through the gap between the fixed frame  330  and the protection cover  320  when the moving assembly  200  is raised. 
     A seating groove  232  may be formed on an upper surface of the insulating member  230  by being depressed downward and on which a lower end of the heater housing  220  is seated. 
     The heater  210  is stored and fixed inside the heater housing  220 . 
     The heater  210  may have a left-right or front-rear long shape and a plurality of heaters may be preferably provided in an inner lower end of the heater housing  220 . 
     Heater brackets  212  may be provided at opposite ends of each heater  210  and guide mounting of each heater  210  or power supply of each heater  210 . 
     A pair of support ends  240  having a symmetrical shape may be provided at left and right portions of a lower inner end of the heater housing  220 , and the support ends  240  may support the plurality of heaters  210 . 
     Meanwhile, the support ends  240  may support the lower end of the link assembly  400 . In other words, upper ends of the support ends  240  may be coupled to the lower end of the link assembly  400 . Therefore, the moving assembly  200  may move up and down while being fixed to the lower end of the link assembly  400 . 
     A heater cover  250  may be provided above the heaters  210  to cover upper portions of the heaters  210 , and the heater cover  250  may have the shape corresponding to the number or the shape of the heaters  210 . 
     The link assembly  400  may have a structure including at least one link, and preferably, the upper end thereof may be rotatably connected to the fixed assembly  300  and the lower end thereof may be rotatably connected to the moving assembly  200 . 
     The link assembly  400  may include a pair of front links  410  and  420  and a pair of the rear links  430  and  440  that are spaced apart from each other forward and rearward at a predetermined distance, and a link frame  450  may be provided at lower ends of the front links  410  and  420  and the rear links  430  and  440 , the link frame  340  being coupled to the moving assembly  200 . 
     In addition, at least one of left and right ends of each of the front links  410  and  420  and the rear links  430  and  440  may be preferably installed to movable while being coupled to the link frame  450 . 
     Specifically, the pair of front links  410  and  420  may be configured such that a front first link  410  and a front second link  420  formed in a ‘X’-shape may be coupled to cross each other to be rotatable on the center, and the pair of rear links  430  and  440  may be configured such that a rear first link  430  and a rear second link  440  formed in a ‘X’-shape may be coupled to cross each other to be rotatable on the center. 
     The lower ends of the front first link  410  and the rear first link  430 , which are installed to be spaced apart from each other forward and rearward by the predetermined distance, may be connected to each other by a connection link  460 , and the lower ends of the front second link  420  and the rear second link  440  may be connected to each other by the connection link  460 . 
     At least one of the left and right lower ends of the front links  410  and  420  and at least one of the left and right lower ends of the rear links  430  and  440  may be movably installed while being coupled to the link frame  450 . According to the present disclosure, as shown in the drawings, the case in which the lower ends of the front first link  410  and the rear first link  430  may be installed to be movable left and right of the link frame  450  is illustrated. 
     Therefore, first link protrusion holes  452  may be preferably formed at a left half portion of the link frame  450 , and the first link protrusion hole  452  may accommodate lower end shafts of the front first link  410  and the rear first link  430  and guide transverse movement thereof. 
     The link frame  450  may include a position member  470 , etc., and the position member  470  may detect the recovery of the moving assembly  200  to the original position thereof. The position member  470  may be formed to protrude upward from an upper surface of the link frame  450  by a predetermined height, and an upper end of the position member  470  may selectively interfere with the position switch  390 . 
     An original position detection means and a contact detection means may be provided at one portion of the fixed assembly  300 , and the original position detection means detects the original position of the moving assembly  200  and the contact detection means detects whether or not a lower end of the moving assembly  200  touches the food inside the cooking chamber  12 . 
     The original position detection means detects whether or not upward movement of the moving assembly  200  in the cooking chamber  12  is completed, and may include the position switch  390 , etc. 
     The contact detection means detects whether or not the lower end of the moving assembly  200  with the heaters  210  touches the food, and may include the protection switch  370 , etc. 
       FIGS.  15  to  24    are views showing an example of each part constituting the movable heater system  100  in detail. 
     First,  FIG.  15    is an exploded-perspective view showing the upper plate  310 , the protection cover  320 , and the fixed frame  330  that constitute the fixed assembly  300 . 
     As shown in the drawing, the upper plate  310  may have a rectangular plate shape, and an upper hole  312  of a rectangular hole with a predetermined size may be formed by being vertically perforated therein. The upper hole  312  serves as a path through which the moving assembly  200  reciprocates up and down. Therefore, the inner size of the upper hole  312  may be preferably formed larger than the outer size of the heater housing  220 . 
     The upper plate  310  may include a plurality of choke pieces  314 . In other words, as shown in the drawing, the plurality of choke pieces  314  may extend upward on an inner circumferential surface of the upper plate  310  having the rectangular frame shape, the plurality of choke pieces being perpendicularly bent upward. 
     Specifically, the plurality of upward protruding choke pieces  314  may be formed on edges of the upper hole  312  formed at the center portion of the upper plate  310 , and the plurality of choke pieces  314  serves to block leakage of electromagnetic waves inside the cooking chamber  12 . 
     Preferably, the protection cover  320  may have a rectangular frame shape corresponding to the upper plate  310 , and the size of an exterior edge may be preferably formed in size smaller than an exterior edge of the upper plate  310 . 
     As shown in the drawing, a protection hole  325  may be formed in the center portion of the protection cover  320  by being vertically perforated, the protection hole  312  corresponding to the upper hole  312 , thereby allowing the vertical movement of the heater housing  220 . 
     As shown in the drawing, preferably, the protection cover  320  may be formed to be stepped so that the height of an inner edge is higher than the height of an outer edge. 
     Specifically, the protection cover  320  may include a protection stepped part  324 , a protection lower end part  326 , and a protection upper end part  328 . The protection stepped part  324  may be formed to have sections of ‘ ┌’ and ‘┐’ shapes (when the protection stepped part is seen from the left and right or the front and rear), the protection lower end part  326  may extend to be perpendicularly bent sideways from a lower end of the protection stepped part  324 , and the protection upper end part  328  may extend to be perpendicularly bent to the upper side from an inner edge of the protection stepped part  324 . 
     The choke pieces  314  of the upper plate  310  may be accommodated under the protection stepped part  324 . 
     As shown in the drawing, the fixed frame  330  may be formed to have a section of ‘∩’-shape (the fixed frame is seen from the side). Therefore, the fixed frame  330  may include a horizontal end  332  of a flat plate shape having a predetermined thickness, and vertical ends  334  extending by being perpendicularly bent downward from front and rear ends of the horizontal end  332 . 
     A pair of link passing holes  336  may be formed in the horizontal end  332  by being vertically perforated. Preferably, the pair of link passing holes  336  may be formed to have predetermined transverse lengths, and here, the link assembly  400  may serve as a passage through which the link passes. In other words, the link passing holes  336  may be installed such that the front links  410  and  420  and the rear links  430  and  440   pass through vertically or allow the front links  410  and  420  and the rear links  430  and  440  to pass therethrough. 
       FIG.  16    is a perspective view showing the structure of the guide members  322 . 
     As shown in the drawing, the guide members  322  may include a roller  322   a , a roller shaft  332   b , a roller support part  322   c , and a roller fixation end  322   d . The roller  322   a  may be selectively brought into contact with the outer surface of the heater housing  220 , the roller shaft  332   b  may be a rotary center of the roller  322   a , the roller support part  322   c  may rotatably support the roller  322   a  or the roller shaft  332   b , and the roller fixation end  322   d  may extend to be perpendicularly bent from a lower end of the roller support part  322   c  and tightly fixed to the protection cover  320 . 
     The roller  322   a  may be shaped in a cylindrical shape or a canister shape, and a material thereof may be an elastic material such as rubber. In addition, the roller  322   a  may be rotatably connected to the roller shaft  332   b , or the roller  322   a  and the roller shaft  332   b  may be fixed to each other. When the roller  322   a  and the roller shaft  332   b  are fixed to each other or provided to be integrated with each other, the roller shaft  332   b  should be connected to an upper end of the roller support part  322   c . 
     The roller support part  322   c  may be shaped in a flat plate having a predetermined thickness as shown in the drawing, or may have a bent shape. 
     The roller fixation end  322   d  may be provided by extending from the roller support part  322   c , and the roller fixation end  322   d  may be bent so as to be perpendicular to the roller support part  322   c  or inclined at a predetermined angle against the roller support part  322   c . 
     The roller fixation end  322   d  may be preferably securely mounted to an upper surface of the protection stepped part  324  of the protection cover  320 . Therefore, an end (inner end) of the roller  322   a  may protrude partially into the inside space of the protection hole  325  of the protection cover  320 , thereby being brought into contact with the outer surface of the heater housing  220  passing through the gap between the protection cover  320  and the fixed frame  330 . 
       FIG.  17    is an exploded-perspective view showing the moving control means  500 . 
     As shown in the drawing, the lead screw  520  of the moving control means  500  may have the transversally long shape, and a screw thread may be preferably formed in the outer circumferential surface thereof. In addition, an insertion protrusion  522  may protrude rightward from a right end of the lead screw  520 , and the insertion protrusion  522  may be fitted into a center groove of the connection coupling  540 . 
     The lead nut  530  may have a nut part  532 , a nut fixation part  534 , etc., and the nut part  532  may have a canister shape so that the lead screw  520  passes therethrough, and the nut fixation part  534  may extend perpendicularly to the nut part  532  and fix the nut part  532  to the moving bracket  560 . 
     A female screw may be formed on an inner circumferential surface of the nut part  532  of the lead nut  530 , the female screw corresponding to the male screw formed on the outer circumferential surface of the lead screw  520  and, preferably, the lead screw  520  and the lead nut  530  may be coupled to each other by screwing. 
     As described above, the connection coupling  540  may be configured of a flexible coupling, and the connection coupling  540  may have a predetermined transverse elasticity or a predetermined amount of transverse length change thereof (reduction and tension of length) may be performed. 
     The motor  510  generates the rotation power as described above and supplies the rotation power to the lead screw  520 . Preferably, the motor shaft (not shown) of the motor  510  may be inserted into and fixed to the center groove of the right end of the connection coupling  540 . 
       FIG.  18    is a perspective view showing the structure of the fixed bracket  550 . As shown in the drawing, the fixed bracket  550  may include a motor seating end  552 , a motor fixation end  554 , and a link fastening end  556 , and the motor seating end  552  may be formed to have a flat surface in an upper surface thereof to support the motor  510 , so that the motor  510  may be securely seated thereon, the motor fixation end  554  may extend from the motor seating end  552  to be perpendicular to the upper side and support a lateral surface of the motor  510 , and the link fastening end  556  may extend upward from each of front and rear ends of the motor seating end  552  and rotatably support the upper ends of the front links  410  and  420  and the rear links  430  and  440 . 
     Fixing fastening ends  558  may be formed on each of left and right ends of on the motor seating end  552 , and the fixing fastening ends  558  may allow the fixed bracket  550  to be securely mounted to the upper surface of the fixed frame  330  by fastening tools such as a bolt, etc. As shown in the drawing, the fixing fastening ends  558  may be formed to have the position lower than the height of the motor seating end  552 . 
     As shown in the drawing, the motor fixation end  554  may be formed into a vertical surface, and a motor hole  554   a  may be formed in the motor fixation end  554  by being perforated transversally. The motor hole  554   a  may have a diameter of a predetermined size, and the motor shaft (not shown) of the motor  510  or the connection coupling  540  may be accommodated in the motor hole  554   a  to passes through transversally. 
     A pair of link fastening ends  556  may have right upper link shafts  557 , and the right upper link shafts  557  may protrude forward and rearward from the pair of link fastening ends  557  to support the upper ends of the front first link  410   and the rear first link  430  so that the upper ends of the front first link  410  and the rear first link  430  may be rotatably connected to the right upper link shafts  557 . 
     In addition, a reinforcement part  556   a  may be formed on a front or rear surface of the pair of link fastening ends  556  by protruding forward or rearward and may serve to reinforce the rigidity. 
       FIG.  19    is a perspective view showing a structure of the moving bracket  560 . As shown in the drawing, the moving bracket  560  may have a square or rectangular section at a lower surface thereof and, preferably, the moving bracket  560  may be closely fixed to the upper surface of the sliding member  352 . 
     As shown in the drawing, a nut support end  562  may protrude rightward from a right surface of the moving bracket  560 . The nut support end  562  may support the lead nut  530  so that the lead nut  530  may be seated and fixed thereon, and as shown in the drawing, the nut support end  562  may have at least a shape corresponding to a shape of a lower end of the lead nut  530  so as to support the lower portion of the lead nut  530 . 
     A screw groove  564  may be formed at the center portion of the moving bracket  560 , the screw groove  564  being depressed downward while passing through transversally. Preferably, the screw groove  564  may be formed larger than an outer diameter of the lead screw  520 , and the lead screw  520  may be accommodated therein. 
     Left upper link shafts  566  may protrude forward and rearward on a front surface and a rear surface of the moving bracket  560 . The left upper link shafts  566  may be a portion where the link upper end of the link assembly  400  may be rotatably connected thereto together with the right upper link shafts  557 . In other words, preferably, the upper ends of the front second link  420  and the rear second link  440  may be rotatably connected to the pair of left upper link shafts  566 , respectively. 
     Furthermore, a reinforcement part  566   a  may protrude forward and rearward from the front surface and the rear surface of the moving bracket  560  together with the reinforcement part  556   a  formed on the link fastening end  556 . 
       FIG.  20    is a front perspective view showing a structure of the protection bracket  360 . 
     As shown in the drawing, the protection bracket  360  may include a protection support part  362  and a protection fixation end  364 , and the protection support part  362  may have predetermined vertical size and thickness, and the protection fixation end  364  may be perpendicularly bent from a lower end of the protection support part  362  and closely fixed to the upper surface of the fixed frame  330 . 
     Furthermore, the protection switch  370  may be installed at the protection support part  362  to interfere with the lead screw  520  and detect whether or not the moving assembly  200  is brought into contact with the food. To this end, a protection installation end  366  may be provided at the protection support part  362  to support the protection switch  370 . 
     In the embodiment, as shown in the drawing, the case in which the protection installation end  366  extends rearward from a rear surface of the protection support part  362  to support the protection switch  370  is illustrated. 
       FIG.  21    is a front perspective view showing a structure of the position bracket  380 . 
     As shown in the drawing, the position bracket  380  may include a position support part  382  and a position fixation end  384 , and the position support part  382  may have a predetermined vertical size and thickness, and the position fixation end  384  may be perpendicularly bent from a lower end of the position support part  382  and closely fixed to the upper surface of the fixed frame  330 . 
     Furthermore, the position support part  382  may include the position switch  390 , etc., and the position switch may interfere with the position member  470  and detect whether or not the moving assembly  200  is recovered to the original position thereof. To this end, a position installation end  386  may be provided at the position support part  382  to support the position switch  390 . 
     In the embodiment, as shown in the drawing, the case in which the position installation end  386  extends rearward from the rear surface of the protection support part  362  and supports the position switch  390 , etc. is illustrated. 
     Meanwhile, the position bracket  380  may be coupled to the fixed bracket  550  and, to this end, a bracket coupling end  388  may be formed at a left end of the position bracket  380  to be perpendicular to the position support part  382 . 
       FIG.  22    is an exploded-perspective view showing a structure of the heater housing  220  and the insulating member  230 . 
     As shown in the drawing, the heater housing  220  may have a rectangular box shape with an open upper portion, and a heater net  224  may be formed at a bottom surface of the heater housing  220 . 
     As shown in the drawing, the heater net  224  may preferably have a net shape with a plurality of vertical through holes. The above described structure is to efficiently transmit radiant heat of the heater  210  provided in the heater housing  220  to the lower space through the bottom surface of the heater housing  220 . 
     As shown in the drawing, the insulating member  230  may have an insulation hole  234  vertically perforated therein so as to have a rectangular frame shape, and when the moving assembly  200  is recovered to an upper end of the cooking chamber  12  as the original position, the insulating member  230  shields the gap between the protection cover  320  and the fixed frame  330  to prevent outward leakage of electromagnetic waves, etc. 
     A size of the insulating member  230  may be preferably formed larger than an inner diameter of the upper hole  312  and the protection hole  325 . In other words, a left-right and front-rear exterior size of the rectangular insulating member  230  may be formed larger than a front-rear and left-right size of the inner diameter of each of the upper hole  312  and the protection hole  325 , and when the moving assembly  200  is recovered to the original position at the upper end of the cooking chamber  12 , preferably, the insulating member  230  and the upper plate  310  may be partially overlapped with each other so that the electromagnetic waves in the cooking chamber  12  are prevented from leaking outward. 
       FIG.  23    is a perspective view showing a structure of the support ends  240  of the moving assembly  200 . 
     As shown in the drawing, the pair of support ends  240  may be installed to be transversally symmetrical to each other, and preferably, the pair of support ends  240  supports the plurality of heaters  210  and allows the moving assembly  200  to be coupled to the lower end of the link assembly  400 . 
     Therefore, each of the support ends  240  may include a bottom support part  242 , a heater seating part  244 , and a link connection part  246 , and the bottom support part  242  may be closely fixed to an upper surface of the bottom surface of the heater housing  220 , the heater seating part  244  may protrude upward from one end of the bottom support part  242  and support the heater  210 , and the link connection part  246  may extend by being perpendicularly bent from another end of the bottom support part  242  upward. 
     The link connection part  246  may be formed in size larger than a vertical height of the heater seating part  244  as shown in the drawing, and a lower end of the link frame  450  of the link assembly  400  may be closely fixed on an upper end of the link connection part  246 . 
     The heater seating part  244  may have grooves depressed downward to allow the heaters  210  to pass through the grooves or to support the heaters  210 , and the heater brackets  212  may be fixed to the grooves. 
       FIG.  24    is an exploded-perspective view showing a main structure of the link assembly  400 . 
     As shown in the drawings, the front first link  410  and the front second link  420  may rotatably cross to each other into a ‘X’-shape on the center portions thereof, and the rear first link  430  and the rear second link  440  may rotatably cross to each other into a ‘X’-shape on the center portions thereof. 
     Therefore, a link center shaft  412  and a link center hole  422  may be respectively formed at the center portions of the front first link  410  and the front second link  420 , and the link center shaft  412  and the link center hole  422  may have shapes corresponding to each other and be rotatably coupled to each other. As shown in the drawing, in the present disclosure, the case in which the link center shaft  412  is formed in the front first link  410  and the link center hole  422  is formed in the front second link  420  is illustrated. In other words, the link center shaft  412  may protrude forward or rearward from a center portion of the front surface or the rear surface of the front first link  410 , and the link center hole  422  may be formed on the center portion of the front second link  420  by being perforated forward and rearward, so that the link center shaft  412  of the front first link  410  may be rotatably installed by being inserted into the link center hole  422  of the front second link  420 . 
     Likewise, the link center shaft  412  and the link center hole  422  may be respectively formed in the center portions of the rear first link  430  and the rear second link  440 , and the link center shaft  412  and the link center hole  422  may have the shapes corresponding to each other and be rotatably coupled to each other. As shown in the drawing, in the present disclosure, the case in which the link center shaft  412  is formed in the rear first link  430  and the link center hole  422  is formed in the rear second link  440  is illustrated. 
     First link holes  414  may be respectively formed in upper ends of the front first link  410  and the rear first link  430  by being perforated forward and rearward, and the right upper link shafts  557  of the fixed bracket  550  may be rotatably inserted into and coupled to the first link holes  414 . 
     Second link holes  424  may be respectively formed in upper ends of the front second link  420  and the rear second link  440  by being perforated forward and rearward, and the left upper link shafts  566  of the moving bracket  560  may be rotatably inserted into and coupled to into the second link holes  424 . 
     First link protrusions  416  may protrude forward or rearward from lower ends of the front first link  410  and the rear first link  430 , and the first link protrusions  416  may be connected to the link frame  450 . 
     Second link protrusions  426  may protrude forward or rearward from lower ends of the front second link  420  and the rear second link  440 , and the second link protrusions  426  may be connected to the link frame  450 . 
     The link frame  450  may include a bottom part  454 , link connection ends  456 , etc., as shown in the drawing, and the bottom part  454  may consist of a flat plate having a predetermined thickness, and the link connection ends  456  may extend by being perpendicularly bent upward from a front end and a rear end of the bottom part  454 . 
     The lower ends of the front first link  410  and the rear first link  430  and the lower ends of the front second link  420  and the rear second link  440  may be rotatably coupled to the link connection ends  456 , respectively. 
     As shown in the drawing, the first link protrusion holes  452  may be formed in left half parts of the link connection ends  456  by being perforated forward and rearward, the first link protrusions  416  formed in the lower ends of the front first link  410  and the rear first link  430  may be accommodated therein. 
     As shown in the drawing, preferably, the first link protrusion holes  452  may be formed to have predetermined transverse lengths, and preferably, the first link protrusions  416  may be transversally movable while being accommodated in the first link protrusion holes  452 . 
     First link protrusion grooves  452   a  may be respectively formed by being depressed downward from left and right ends of each of the first link protrusion holes  452 . The first link protrusion grooves  452   a  maintains a situation in which the moving assembly  200  moves vertically and then is temporarily stopped, and serves as a portion where the first link protrusions  416  temporarily stay. 
     As shown in the drawing, second link protrusion holes  458  may be formed in right half portions of the link connection ends  456  by being perforated forward and rearward, and the second link protrusions  426  formed in the lower ends of the front second link  420  and the rear second link  440  may be accommodated therein. 
     According to the above structure, the second link protrusions  426  maintain the state of being accommodated in the second link protrusion holes  458 , and the first link protrusions  416  are transversally rotatable while being accommodated in the first link protrusion holes  452 , so that the lower ends of the front first link  410  and the rear first link  430  may move closer to or away from the lower ends of the front second link  420  and the rear second link  440  and thus the link connection ends  456  may move vertically. 
     Hereinbelow, the operation of the cooking appliance according to the present disclosure having the above-described structure will be described with reference to the accompanying drawings. 
     First, as shown in  FIG.  1   , before cooking starts with the movable heater system  100  installed at the upper surface of the casing  10 , as shown in  FIGS.  2  to  7   , the moving assembly  200  of the movable heater system  100  may be located at the upper end of the cooking chamber  12 . 
     Therefore, at this time, since the moving assembly  200  is raised to the upper side, the first link protrusions  416  of the front first link  410  and the rear first link  430  may be located at left ends of the first link protrusion holes  452  of the link frame  450 . 
     In this state, when the lead nut  530  moves gradually rightward in response to rotation (forward rotation) of the motor  510 , the upper ends of the front first link  410  and the front second link  420  and the upper ends of the rear first link  430  and the rear second link  440  may move closer to each other, so that the moving assembly  200  may move to the lower space in the cooking chamber  12 . 
     Meanwhile, when the moving assembly  200  crashes with the food in the cooking chamber  12  while being lowered in the cooking chamber  12 , the moving assembly  200  can no longer be lowered, so that the lead nut  530  may be restrained. As described above, when the motor  510  continues forward rotation and movement of the lead nut  530  stops, tension is generated in the connection coupling  540  in response to rotation of the lead screw  520 , and the left end of the lead screw  520  may stretch leftward. 
     When the left end of the lead screw  520  moves leftward by a predetermined distance, the protection switch  370  installed adjacent to the lead screw  520  is operated so that the rotation of the motor  510  stops. By the above-described process, a damage to the parts such as the connection coupling  540  in addition to the food in the cooking chamber  12  is prevented. 
     Of course, at this time, it is possible that the motor  510  performs reverse rotation to control the moving assembly  200  so that the moving assembly  200  is raised. 
     The movable heater system  100  with the moving assembly  200  moving downward below the upper plate  310  and lowered into the inside space of the cooking chamber  12  is shown in  FIGS.  8  to  11   . 
     At this time, the first link protrusions  416  of the front first link  410  and the rear first link  430  may be located at the right ends of the first link protrusion holes  452  of the link frame  450 . 
     When the moving assembly  200  is lowered inside the cooking chamber  12 , the heaters  210  may move closer to the food inside the cooking chamber  12  so that cooking of the food can be performed more rapidly. 
     When the cooking is completed in the above-described state, the moving assembly  200  may be raised and be recovered to the original position thereof. For raising of the moving assembly  200 , the motor  510  should be controlled to perform reverse rotation, and when the lead nut  530  is moves gradually leftward by the reverse rotation of the motor  510 , the upper ends of the front first link  410  and the front second link  420  and the upper ends of the rear first link  430  and the rear second link  440  may move away from each other so that the moving assembly  200  may move upward of the cooking chamber  12  and be recovered to the original position. 
     The position member  470 , the position switch  390 , etc. may detect whether or not the moving assembly  200  is raised and recovered to the original position thereof. when the gap between the insulating member  230  of the moving assembly  200  and the upper plate  310  is less than or equal to a preset gap, the upper end of the position member  470  provided in the moving assembly  200  may operate the position switch  390  so that the motor  510  may be controlled to stop. 
     By the control, a crash between or damages to the upper plate  310  and the insulating member  230  can be prevented and leakage of electromagnetic waves via the gap between the upper plate  310  and the insulating member  230  can be prevented. 
     Furthermore, only when the moving assembly  200  is recovered to the original position thereof by the position switch  390 , use of electromagnetic waves of the cooking appliance is controlled to be possible. Therefore, when the moving assembly  200  is lowered downward into the cooking chamber  12 , since the use of electromagnetic waves of the cooking appliance is blocked, so that the leakage of electromagnetic waves is prevented. 
     The scope of the present disclosure is not limited to the above illustrated embodiment, and those skilled in the art will appreciate that various modifications, additions and substitutions based on the present disclosure are possible, without departing from the scope and spirit of the present disclosure.