Patent Publication Number: US-2023137868-A1

Title: Cooking appliance

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0146152, filed on Oct. 28, 2021, and Korean Patent Application No. 10-2022-0001815, filed on Jan. 5, 2023, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates generally to a cooking appliance. 
     Description of the Related Art 
     Various types of cooking appliances are used to heat food at home or in restaurants. For example, such cooking appliances may include microwave ovens, induction heating electric ranges, and grill heaters. 
     A microwave oven heats food by using molecules in a high-frequency electric field vibrating strongly to generate heat. The microwave oven can heat food evenly in a short time. 
     An induction heating electric range is a cooking appliance that uses electromagnetic induction to heat an object to be heated. Specifically, when high-frequency power of a predetermined size is applied to a coil, the induction heating electric range generates eddy currents in the object to be heated, which is made of a metal substance, using a magnetic field generated around the coil, and thus heating the object to be heated. 
     A grill heater is a cooking appliance that heats food by radiating or convection of infrared heat. The grill heater allows infrared heat to pass through the food, so that the food can be cooked evenly throughout. 
     Accordingly, as the cooking appliances using various types of heat sources are released, the number and types of cooking appliances provided to users have increased, and there is a problem in that the cooking appliances occupy a large volume in the living space. Accordingly, there is increased demand i for a composite cooking appliance having a plurality of heating modules. In addition, it is necessary to develop a cooking appliance that simultaneously uses a plurality of heating methods so that food in the object to be heated is cooked more uniformly and quickly. 
     U.S. Pat. No. 6,987,252 B2 (related art 1) disclosed the technique for cooking food using radiant heat and convection heat along with microwaves. However, microwaves or radiant heat and convection heat using heaters are limited in rapidly heating food. In order to solve this problem, recently, induction heating type cooking appliances are being used. 
     For example, Korean Patent Application Publication No. 10-2018-0115981 (related art 2) disclosed a cooking appliance for using microwave and inductive heat sources at the same time in one device. 
     However, the cooking appliance in the related art 2 is configured to cover induction heating coils by a shield cover in order to prevent microwaves from approaching the inductive heat source during usage of the microwave heat source. Therefore, in the case of the related art 2, the two types of heat sources are not used at the same time, and furthermore, the cooking appliance in the related art 2 has a discomfort in that the shielding cover must be rotated each time the microwave heat source is used. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present disclosure has been made keeping in mind the above problems occurring in the related arts, and an objective of the present disclosure is to use a microwave heat source (first heat source module) and an inductive heat source (second heat source module) at the same time. 
     Another objective of the present disclosure is to fix a shield filter for blocking microwaves an inductive heat source without a separate fastening tool. 
     A further objective of the present disclosure is to prevent microwaves and foreign materials from transferring into the inside space of the coil assembly. 
     According to features of the present disclosure for achieving the above-described objectives, a casing may have a cavity therein, and a first heat source module may be arranged in the casing, and be configured to emit microwaves. A second heat source module may be arranged at a bottom surface of the casing and be configured to emit magnetic fields. In addition, the second heat source module may include a base plate having a base hole that is open at a center portion thereof, and a supporter arranged below the base plate. A coil assembly may be arranged between the base plate and the supporter, and the coil assembly may include a coil base and a working coil. 
     Herein, a shield filter of the second heat source module may cover the working coil, and an outer end of the shield filter may be arranged between the base plate and the coil base. The shield filter may prevent electromagnetic waves generated when a microwave heat source(first heat source module) is used from affecting the second heat source module, so that the microwave heat source (first heat source module) and the inductive heat source (second heat source module) may be used at the same time. 
     In addition, the outer end of the shield filter may be pressed between the base plate and the coil base. Therefore, the shield filter may e fixed between the base plate and the coil assembly without a separate fastening tool. 
     Furthermore, the base plate may include a filter cover portion arranged along a rim of the base hole, and the filter cover portion may be stacked on the shield filter. Therefore, the filter cover portion may fix an upper portion of the shield filter. 
     Furthermore, an outer end of the coil base may include a filter supporter arranged parallel to the filter cover portion, and the filter supporter may be stacked under the shield filter. Therefore, the upper and lower portions of the shield filter may be fixed by the filter cover portion and the filter supporter. 
     Specifically, the filter cover portion and the filter supporter may be respectively in surface-contact with the shield filter. Accordingly, a gap through which microwaves may leak may be further narrowed. 
     Furthermore, the filter cover portion may be connected to a first inclined portion, and the filter supporter may be connected to the second inclined portion. Herein, the first inclined portion and the second inclined portion may be arranged to face each other at positions outside the outer end of the shield filter in a radial direction of the shield filter. Therefore, foreign materials, etc. may be prevented from leaking toward the shield filter. 
     Furthermore, a gap between the first inclined portion and the second inclined portion may be formed to be gradually narrowed as going further from the outer end of the shield filter. In this state, the first inclined portion and the second inclined portion may press the outer end of the shield filter. 
     The coil base may have a clearance between the filter cover portion and an outer end of the working coil, and the clearance may be continuously formed in a circumferential direction of the coil base. The clearance may form an empty space around the working coil, so that transfer of microwaves or foreign materials into the working coil may be prevented. 
     Furthermore, a diameter of the shield filter may be larger than a diameter of the working coil, and may be smaller than a diameter of the supporter. Simultaneously, the diameter of the shield filter is larger than a diameter of the base hole, and may be smaller than a diameter of the coil base. Therefore, the shield filter may fully cover the upper portion of the working coil so that microwaves transferred to the working coil may be effectively blocked, and magnetic fields generated by the working coil may be efficiently transferred to the upper portion via the cover plate. 
     Furthermore, the filter cover portion, the first inclined portion, the depressed portion, and the seating portion may be sequentially connected to each other at the base plate. Here, the seating portion may be formed higher than the filter cover portion. Accordingly, vibrations transferred to the cover plate when the working coil is operated may be reduced, and noise of the cooking appliance may be reduced. 
     Furthermore, an outer end of the seating portion may be connected to a seating fence, and the seating fence may protrude upward and surround an edge of the cover plate. In addition, both the seating fence and the cover plate may provide a bottom surface of the cavity, and a surface of the seating fence and a surface of the cover plate may form a continuous surface together. Therefore, the bottom surface of the cavity can be formed flat, and the cavity may be easily cleaned. 
     Furthermore, the mounting bracket may be arranged between the base plate and the supporter. Here, the mounting bracket may include a bracket lower portion coupled to the supporter and a bracket upper portion coupled to the base plate. In addition, the bracket connection portion may connect the bracket lower portion to the bracket upper portion. 
     As described above, the cooking appliance according to the present disclosure have at least the following effects. 
     In the present disclosure, the shield filter is applied to the inductive heat source (second heat source module), and the shield filter can prevent leakage of microwaves. The shield filter can prevent electromagnetic waves generated when the microwave heat source (first heat source module) is used from affecting the second heat source module, so that the microwave heat source (first heat source module) and the inductive heat source (second heat source module) can be used at the same time. Therefore, as the food can quickly heated, the cooling time can be reduced. 
     In addition, in the present disclosure, the shield filter may be arranged between the base plate and the coil assembly that constitute the second heat source module. Here, the coil assembly can be fixed to the base plate by the supporter, and the shield filter can be fixed between the base plate and the coil assembly without a separate fastening tool. Therefore, the embodiment can eliminate a risk of arc discharge occurring when an electric field is concentrated to an edge of a hole to which the fastening tool is used or a sharp screw thread, and the stability of the cooling appliance can be improved. 
     Specifically, in the present disclosure, the upper and lower portions of the outer end, the edge of the shield filter, can be respectively pressed by the base plate and the coil base. Therefore, the air-tightness of the shield filter can be improved, and leakage of electromagnetic waves toward the working coil can be efficiently blocked. 
     Furthermore, in the present disclosure, the first inclined portion of the base plate and the second inclined portion of the coil base can be arranged to face each other with the outer end of the shield filter located between the first and second inclined portions, and the first inclined portion and the second inclined portion can be extended in a direction away from the outer end of the shield filter. The first inclined portion and the second inclined portion can reduce the gap between the base plate and the coil base, thereby preventing both electromagnetic waves and foreign materials from flowing to the shield filter. 
     Furthermore, the first inclined portion and the second inclined portion are composed of facing inclined surfaces, so when the base plate and the coil assembly are assembled with each other, the two members can be naturally aligned in X and Y-axial directions. Therefore, the assembly performance of the second heat source module can be improved. 
     Furthermore, the seating portion of the base plate at which the cover plate is placed can be formed higher than the filter cover portion fixing the shield filter. Due to the height difference, the cover plate is prevented from touching the filter cover portion, but can touch only the seating portion, so that the cover plate and the shield filter can be spaced apart from each other. Accordingly, vibrations transferred to the cover plate when the working coil is operated can be reduced, and noise of the cooking appliance can be reduced. 
     In addition, the diameter of the shield filter may larger than the diameter of the working coil, and may be smaller than the diameters of the cover plate and the supporter. Accordingly, the shield filter can fully cover the upper portion of the working coil so as to efficiently block microwaves transferred to the working coil. On the other hand, magnetic fields generated from the working coil can be efficiently transferred to the upper portion via the cover plate. 
     Furthermore, in the present disclosure, the outer end of the working coil and the filter supporter of the coil base are spaced apart from each other, and a kind of empty space can be formed therebetween. Therefore, the gap between the outer end of the shield filter and the filter supporter through which electromagnetic waves can flow can be spaced away from the working coil, and transfer of microwaves to the working coil can be completely prevented. 
     The objects of the present disclosure are not limited to the above-described objects, and other objects and advantages not mentioned may be understood by the following description, and will be more clearly understood by the embodiments of the present disclosure. In addition, it will be easily seen that the objects and advantages of the present disclosure may be realized by the means described in the claims and combinations thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings constitute a part of this specification and illustrate one or more embodiments of the present disclosure and together with the specification, explain the present disclosure. 
         FIG.  1    is a perspective view showing a cooking appliance according to an embodiment of the present disclosure. 
         FIG.  2    is an exploded-perspective view showing components constituting the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  3    is an exploded perspective view showing remaining components of excluding a door, an outer side plate, and an outer upper plate from the components constituting the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  4    is an exploded-perspective view showing the structure shown in  FIG.  3    at the opposite angle of  FIG.  3   . 
         FIG.  5    is a perspective view showing the embodiment shown in  FIG.  1    without the door and the outer casing. 
         FIG.  6    is a perspective view showing the embodiment shown in  FIG.  1    without the door and the outer casing at the opposite angle of  FIG.  2   . 
         FIG.  7    is a sectional view taken along line VII-VII′ in  FIG.  1   . 
         FIG.  8    is a front view showing the cooking appliance according to the embodiment of the present disclosure without the door and a part of the outer casing among the components constituting the cooking appliance. 
         FIG.  9    is a plan view showing the cooking appliance according to the embodiment of the present disclosure without the door and a part of the outer casing among the components constituting the cooking appliance. 
         FIG.  10    is a rear view showing the cooking appliance according to the embodiment of the present disclosure without the door and a part of the outer casing among the components constituting the cooking appliance. 
         FIG.  11    is a right side view showing the cooking appliance according to the embodiment of the present disclosure without the door and a part of the outer casing among the components constituting the cooking appliance. 
         FIG.  12    is a left side view showing the cooking appliance according to the embodiment of the present disclosure without the door and a part of the outer casing among the components constituting the cooking appliance. 
         FIG.  13    is a front view showing an exhaust duct constituting the cooking appliance according to the embodiment of the present disclosure mounted to an inner casing. 
         FIG.  14    is an exploded-perspective view showing the inner casing, an outer front plate, an outer upper plate, and a second heat source module that constitute the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  15    is an exploded-perspective view showing the configuration of the inner casing and a first heat source module that constitute the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  16    is a perspective view showing an assembled state of the configuration of the inner casing and the first heat source module that constitute the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  17    is an exploded-perspective view showing the outer upper plate, a first cooling fan module arranged at the outer upper plate, and a distance sensor module of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  18    is an exploded-perspective view showing the configuration of a power supply unit arranged at an insulation rear plate and an insulation rear plate of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  19    is an exploded-perspective view showing components of the second heat source module of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  20    is a perspective view showing the configuration of a lower supporter and a working coil assembly among the components of the second heat source module of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  21    is a sectional view showing the inner structure of the second heat source module of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  22    is a sectional view showing the inner structure of the second heat source module of the cooking appliance according to the embodiment of the present disclosure. 
         FIGS.  23  to  26    are assembly sequence views showing an assembly process in which the second heat source module of the cooking appliance according to the embodiment of the present disclosure is sequentially assembled. 
         FIG.  27    is a perspective view showing the configuration of a third heat source module of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  28    is an exploded-perspective view showing components of the third heat source module shown in  FIG.  27   . 
         FIG.  29    is a perspective view showing the third heat source module in  FIG.  27    arranged at a first location. 
         FIG.  30    is a perspective view showing the third heat source module in  FIG.  27    arranged at a second location. 
         FIG.  31    is a sectional view showing a state where the third heat source module in  FIG.  27    is arranged at a first location and a location switch thereof is pressed by an operation pin. 
         FIG.  32    is a perspective view showing a state where the distance sensor and a lighting fixture of the cooking appliance according to the embodiment of the present disclosure are separated from the outer upper plate. 
         FIG.  33    is a perspective view showing a state where the distance sensor of the cooking appliance according to the embodiment of the present disclosure is arranged at the outer upper plate. 
         FIG.  34    is an exploded-perspective view showing components of the distance sensor of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  35    is a sectional view showing a state where the distance sensor of the cooking appliance according to the embodiment of the present disclosure is arranged at the outer upper plate. 
         FIG.  36    is an exploded-perspective view showing a state where a camera sensor of the cooking appliance according to the embodiment of the present disclosure is separated from the inner casing. 
         FIG.  37    is a perspective view showing a state where the camera sensor of the cooking appliance according to the embodiment of the present disclosure is arranged at the inner casing. 
         FIG.  38    is an exploded-perspective view showing components of the camera sensor shown in  FIG.  36   . 
         FIG.  39    is a perspective view showing the configuration of a camera housing among the components of the camera sensor shown in  FIG.  36   . 
         FIG.  40    is a sectional view showing a state where the camera sensor of the cooking appliance according to the embodiment of the present disclosure is arranged at the inner casing. 
         FIG.  41    is a sectional view taken at a different angle from  FIG.  40   , which shows a state where the camera sensor of the cooking appliance according to the embodiment of the present disclosure is arranged at the inner casing. 
         FIG.  42    is a perspective view taken from the inside space of a cavity, which shows a state where the camera sensor of the cooking appliance according to the embodiment of the present disclosure is arranged at the inner casing. 
         FIG.  43    is a perspective view showing the configuration of an exhaust duct, a humidity sensor arranged at the exhaust duct, and a temperature sensor of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  44    is an exploded-perspective view showing components of a second cooling fan module of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  45    is a perspective view showing the structure of a duct module of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  46    is an exploded-perspective view showing components of the duct module of the cooking appliance according to the embodiment of the present disclosure. 
         FIG.  47    is a perspective view showing a cooking appliance according to a second embodiment of the present disclosure. 
         FIG.  48    is a perspective view taken at a different angle from  FIG.  47   , which shows the second embodiment shown in  FIG.  47   . 
         FIG.  49    is a plan view showing the structure of the second embodiment shown in  FIG.  47   . 
         FIG.  50    is a rear view showing the structure of the second embodiment shown in FIG. 
         FIG.  51    is a left side view showing the structure of the second embodiment shown in  FIG.  47   . 
         FIG.  52    is a right side view showing the structure of the second embodiment shown in  FIG.  47   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The above-described objects, features, and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present disclosure pertains will be able to easily practice the technical spirit of the present disclosure. In describing the present disclosure, when it is determined that a detailed description of a known technique related to the present invention may unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted. Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components. 
     Although the first, second, etc. are used to describe various components, it is understood that these components are not limited by these terms. These terms are only used to distinguish one component from other components, and unless otherwise stated, it is understood that the first component may also be the second component. 
     As used herein, unless specifically stated otherwise, each component may be singular or plural. 
     As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In the present disclosure, terms such as “consisting of” or “comprising” should not be construed as necessarily including all of the various components or various steps described in the specification, and should be construed that some components or some steps may not be included, or additional components or steps may be further included. 
     As used herein, various singular forms “a,” “an” and “the” are intended to include various plural forms as well, unless context clearly indicates otherwise. For example, a term “a” or “an” shall mean “one or more,” even though a phrase “one or more” is also used herein. Use of the optional plural “(s),” “(es),” or “(ies)” means that one or more of the indicated feature is present. 
     As used herein, “up-down direction” means the up-down direction of the cooking appliance in a state in which the cooking appliance (or other components) is installed for daily use. “Left-right direction” means a direction perpendicular to the up-down direction, and the front-rear direction means a direction perpendicular to both the up-down direction and the left-right direction. “Bilateral direction” or “lateral direction” has the same meaning as the left-right direction, and these terms may be used interchangeably in the present specification. 
     Various terminology used herein can imply direct or indirect, full or partial, temporary or permanent, action or inaction. For example, when an element is referred to as being “on,” “connected” or “coupled” to another element, then the element can be directly on, connected or coupled to the other element or intervening elements can be present, including indirect or direct variants. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. A cooking appliance of the present disclosure is provided to cook object to be cooked (hereinbelow, which will be referred to as “food”) using a plurality of heat sources. The cooking appliance of the present disclosure may include a first heat source module  400 , a second heat source module  500 , and a third heat source module  600 . The first heat source module  400 , the second heat source module  500 , and the third heat source module  600  may be respectively arranged in the cooking appliance of the present disclosure, and may consist of different types of heat sources. Hereinbelow, these plurality of heat sources, cooling fan modules for cooling the heat sources, and devices for measuring a state of the cooking appliance will be described in priority. 
       FIG.  1    is a view showing a cooking appliance according to an embodiment of the present disclosure. As shown, in the embodiment, a cavity S may be provided inside the cooking appliance, and the cavity S may be opened and closed by a door  300 . Except for the door  300 , the other parts of the cooking appliance may be shielded by a casing  100 ,  200 . The cavity S is an empty portion or hollowed out space, may be referred to as a cooking chamber. The casing  100 ,  200  may include the inner casing  100  and an outer casing  200 . Specific structures of the inner casing  100  and the outer casing  200  will be described below. 
     In the embodiment shown in  FIG.  1   , the first heat source module  400  may be arranged at a left portion of the cooking appliance and the second heat source module  500  may be arranged at the bottom of the cooking appliance. The third heat source module  600  may be arranged at an upper portion of the cooking appliance. As described above, in the embodiment, the first heat source module  400 , the second heat source module  500 , and the third heat source module  600  may be respectively arranged at different surfaces among six surfaces constituting the casing  100 ,  200 , and the arrangement of such is not limited to the particular arrangement shown in  FIG.  1   . 
       FIG.  2    is a view showing disassembled components constituting the cooking appliance, wherein the third heat source module  600  is exposed. In the embodiment, the third heat source module  600  may move between a first location and a second For example, as shown, the third heat source module  600  may move toward the bottom surface of the cavity S while being raised, i.e., toward the second heat source module  500 . 
     Alternatively, for example, the first heat source module  400  may be arranged at a right portion of the cooking appliance, and the third heat source module  600  may be arranged at a rear surface of the cooking appliance. Furthermore, the third heat source module  600  may be fixed to the casing  100 ,  200  without moving. 
     As shown in  FIG.  2   , the inner casing  100  constituting the casing  100 ,  200  may be provided to surround the cavity S. The inner casing  100  may include a pair of inner side plates  110  and an inner rear plate  120  connecting the pair of inner side plates  110  to each other. The pair of inner side plates  110  and the inner rear plate  120  may be formed approximately in a “c”-like shape. 
     The third heat source module  600  may be arranged at an upper portion of the inner casing  100 . In other words, the third heat source module  600  may shield an upper portion of the cavity S. The second heat source module  500  may be arranged at a lower portion of the inner casing  100 . The second heat source module  500  may shield a lower portion of the cavity S. Therefore, the second heat source module  500  and the third heat source module  600  may also be considered as a part of the inner casing  100  surrounding the cavity S. 
     The pair of inner side plates  110  may respectively include an inlet port  123  and an outlet port  125 . The inlet port  123  and the outlet port  125  may be respectively on the pair of side plates, and may be arranged at the opposite sides to each other. The inlet port  123  and the outlet port  125  are open toward the cavity S to connect the cavity S to the outside space. 
     The inlet port  123  may be open toward the cavity S. A supply duct  910  to be described below may be arranged on an outer surface of one of the pair of side plate with the inlet port  123  and air may be supplied through the inlet port  123 . Water evaporates from the food cooked by the first heat source module  400 , so that moisture may be generated inside the cavity S. In order to remove such moisture, it is necessary to supply air into the cavity S. In the embodiment, air may be injected through the inlet port  123  and may be discharged through the outlet port  125  located opposite to the inlet port  123 . Herein, air supplied through the inlet port  123  may be a part of air acting heat dissipation (cooling) while passing through the inside space of the casing  100 ,  200 . 
     As shown in  FIG.  3   , the inner rear plate  120  may include a camera mounting part  128 . A camera module  730  to be described below may be mounted to the camera mounting part  128 . The camera mounting part  128  may have a shape of recessing rearward from the cavity S, but, at a view taken from the rear side of the inner rear plate  120 , the camera mounting part  128  may have a protruding structure. Preferably, the camera mounting part  128  may be arranged at a center portion of the inner rear plate  120 , so that the camera module  730  may face the center of the cavity S. A specific structure of the camera mounting part  128  will be described below with the camera module  730 . 
     An inner upper plate  160  may be arranged at an upper portion of the pair of inner side plates  110 . Referring to  FIGS.  3  and  4   , the inner upper plate  160  may have approximately a rectangular frame shape, and may be arranged along an upper edge of the pair of side plates. An upper plate opening  162  (referring to  FIG.  14   ), i.e., a kind of empty or hollow portion, may be provided in a center portion of the inner upper plate  160 . The third heat source module  600  may be raised and lowered through the upper plate opening  162 . 
     Referring to  FIG.  14   , a chock part  161  may be provided at the inner upper plate  160 . The chock part  161  may be an electromagnetic wave shielding structure to prevent electromagnetic waves in the cavity S from leaking outward through a gap between the cavity S and the upper plate opening  162 . The chock part  161  may be provided along an edge of the upper plate opening  162 . 
     The inner upper plate  160  may include a lighting mounting part  165 . The lighting mounting part  165  may be provided at an upper portion of the inner upper plate  160 . A lighting fixture  790  to be described below may be arranged in the lighting mounting part  165 . In the embodiment, the lighting mounting part  165  may be provided at a middle portion of a front portion of the inner upper plate  160 , which is close to the door  300 . 
     Referring to  FIG.  14   , the lighting mounting part  165  may have an inclined shape. Therefore, when the lighting fixture  790  is arranged in the lighting mounting part  165 , an angle emitting light may be an angle inclined toward the center of the cavity S. For reference, in  FIG.  14   , Reference numeral  163  is a sensing hole, and a distance sensor  710  to be described below may be arranged in the sensing hole  163 . 
     The outer casing  200  may be arranged outside of the inner casing  100 . The outer casing  200  may enclose the inner casing  100 . An electric chamber, i.e., a kind of space, may be provided between the inner casing  100  and the outer casing  200 . A main controller  700 , a first cooling fan module  810 , a second cooling fan module  850 , and a power supply unit  770  that will be described below may also be arranged in the electric chamber. The third heat source module  600  may also be arranged between the inner casing  100  and the outer casing  200 . 
     As shown in  FIG.  2   , the outer casing  200  may include a pair of outer side plates  210 , an outer rear plate  220  connecting the pair of outer side plates  210  to each other, an outer upper plate  230  arranged at an upper portion of the outer casing  200 , an outer front plate  240  arranged at a front portion of the outer casing  200 , and the outer lower plate  250 . The outer casing  200  may cover the entire outer surfaces of the inner casing  100 , and therefore, the inner casing  100  may be covered from the outside space by the outer casing  200 . 
     A part of the outer rear plate  220  may be separated from the outer casing. Referring to  FIG.  10   , when a part of the outer rear plate  220  is separated, the inside space of a third electric chamber ES 3  may be exposed outward through a rear plate through portion  221   a . An operator may maintain parts by approaching the exposed inside space of the third electric chamber ES 3 . Reference numeral  222  may be a cable through portion provided to discharge a power cable to the outside space. 
     The outer upper plate  230  may be formed approximately in a rectangular plate. The outer upper plate  230  may be arranged above the third heat source module  600 . The outer upper plate  230  may shield the third heat source module  600 . The outer upper plate  230  may be considered as a part arranged at the outer mouse side of the upper portion of the cooking appliance. 
     An upper plate shielding part  232  may be provided at a front portion of the outer upper plate  230 . The upper plate shielding part  232  may be formed such that the front portion of the outer upper plate  230  is perpendicularly bent. The upper plate shielding part  232  may support a display substrate (not shown) provided in a display module  350  to be described below, in a rear-to-front direction. The upper plate shielding part  232  may prevent the inner structure of the cooking appliance from being exposed forward through the display module  350 . Reference numeral  235  may be a hole through which a part of a wire harness may pass rearward, and may be omitted. 
     The outer front plate  240  may be arranged at the rear side of the door  300 . The outer front plate  240  may have approximately a rectangular frame shape. A center portion of the outer front plate  240  may be empty to expose the inside space of the cavity S to the outside space. The outer front plate  240  may be coupled to front portions of the pair of inner side plates  110  constituting the inner casing  100 . Therefore, the outer front plate  240  may be considered as a part of the inner casing  100 , not a part of the outer casing  200 . 
     In the embodiment, the height of the outer front plate  240  is above the pair of inner side plates  110  constituting the inner casing  100 , so that an upper rear portion and a lower rear portion of the outer front plate  240  may have empty portions, respectively. These empty portions may serve as electric chambers in which parts are mounted and may serve as a heat dissipation space to dissipate heat of the parts. For example, the first cooling fan module  810 , the second cooling fan module  850 , and the third heat source module  600 , which will be describe below, may be arranged at a rear side of a portion of the outer front plate  240 , the portion protruding further upward than the pair of inner side plates  110 . 
     The outer front plate  240  may have an inlet part  242  and an air outlet part  243 . In the embodiment, the air inlet part  242  may be arranged in an upper portion of the outer front plate  240  and the air outlet part  243  may be arranged in a lower portion of the outer front plate  240 . Referring to  FIG.  8   , the air inlet part  242  and the air outlet part  243  may extend in a transverse direction of the outer front plate  240 . Outside air may be introduced into a first electric chamber ES 1  through the air inlet part  242  to cool the parts including heat sources, and air heated by heat of the parts may be discharged to the outside space through the air outlet part  243 . 
     As shown in  FIG.  5   , the air inlet part  242  may be formed in the portion of the outer front plate  240 , the portion protruding further upward than the pair of inner side plates  110 . The first cooling fan module  810  and the second cooling fan module  850  may be arranged at the rear side of the air inlet part  242 . Therefore, when the first cooling fan module  810  and the second cooling fan module  850  are operated, outside air may be introduced, through the air inlet part  242 , into the first electric chamber ES 1  provided between the outer upper plate  230  and the inner upper plate  160 . 
     The air outlet part  243  may be formed in a portion of the outer front plate  240 , the portion protruding further downward than the second heat source module  500 . A second electric chamber ES 2  formed between the second heat source module  500  and the outer lower plate  250  may be provided at the rear side of the air outlet part  243 . Air introduced into the cooking appliance through the air inlet part  242  may be discharged to the air outlet part  243  through the second electric chamber ES 2 . 
     Referring to  FIG.  5   , a hinge hole  244  may be provided in a lower portion of the outer front plate  240 . The hinge hole  244  may be a portion through which a hinge assembly (not shown) of the door  300  may pass. The hinge assembly may pass through the hinge hole  244 , and then be coupled to a hinge holder  253  provided at the outer lower plate  250 . 
     A connector  245  may be provided at the upper portion of the outer front plate  240 . The connector  245  may be arranged at the upper portion of the outer front plate  240 . The connector  245  is electrically connected to the main controller  700 , and an operator may control the main controller  700  by contacting the connector  245 . The connector  245  may be omitted or be arranged at the outer rear plate  220  or the pair of outer side plates  210 . 
     A shield frame  247  may be provided at the rear side of the outer front plate  240 . The shield frame  247  may be arranged behind the air inlet part  242  of the outer front plate  240 , and may block access to wire harness from the outside space, and shield the parts in the cooking appliance. The shield frame  247  may have a plurality of slits, so that the air introduced through the air inlet part  242  may pass through the plurality of slits. 
     The outer casing  200  may include the outer lower plate  250 . The outer lower plate  250  may be arranged below the inner casing  100 . In the embodiment, the outer lower plate  250  may connect the outer rear plate  220  to the outer front plate  240 . Furthermore, the outer lower plate  250  may be connected to an insulation rear plate  280  to be described below. As shown in  FIG.  5   , the outer lower plate  250  may be spaced apart from the second heat source module  500 , and the gap between the outer lower plate  250  and the second heat source module  500  may serve as the second electric chamber ES 2 . 
     For reference, in  FIG.  6   , the outer lower plate  250  is shown in an omitted state, as shown in  FIG.  6   , the second electric chamber ES 2 , i.e., a kind of an empty portion or space, may be provided between the outer front plate  240  and the insulation rear plate  280 . Air may flow through the second electric chamber ES 2 , and finally the air may be discharged to the outside space through the air outlet part  243 . 
     Meanwhile, regarding the electric chamber as described above, the electric chamber may be divided into a plurality of spaces. According to the embodiment, the electric chamber may be divided into the first electric chamber ES 1  to a fifth electric chamber ES 5 : (i) the first electric chamber ES 1  may be provided between the inner upper plate  160  and the outer upper plate  230  (referring to  FIG.  9   ); (ii) the second electric chamber ES 2  may be provided between the second heat source module  500  and the outer lower plate  250  (referring to  FIG.  7   ); (iii) the third electric chamber ES 3  may be provided between the insulation rear plate  280  to be described below and the outer rear plate  220  (referring to  FIG.  10   ); and (iv) the fourth electric chamber ES 4  and the fifth electric chamber ES 5  may be respectively provided between the pair of inner side plates  110  and the pair of outer side plates  210  (referring to  FIGS.  11  and  12   ). The first electric chamber ES 1  and the fifth electric chamber ES 5  may be arbitrarily divided, and may be connected to each other. 
     Herein, each electric chamber may be provided at each surface of the casing. The first electric chamber to the fifth electric chamber (ES 1 ˜ES 5 ) may be provided at different surfaces of the hexahedron casing. The first heat source module  400 , the second heat source module  500 , and the third heat source module  600  may be arranged at different surfaces of the casing. 
     The outer casing  200  may include the insulation upper plate  270 . The insulation upper plate  270  may be arranged between the outer upper plate  230  and the inner upper plate  160 . Since high heat is generated during the cooking process in the cavity S, the temperature of the inner upper plate  160  may increase. The insulation upper plate  270  may reduce heat transferred from the inner upper plate  160  to the outer upper plate  230 . The insulation upper plate  270  may have a rectangular frame shape with an empty center portion same as the inner upper plate  160 . A movable opening  272  provided in a center portion of the insulation upper plate  270  may be connected to the upper plate opening  162  of the inner upper plate  160 , and the third heat source module  600  may move through the movable opening  272  and the upper plate opening  162 . 
     As shown in  FIGS.  3  to  5   , the distance sensor  710  and a cooling fan module  810 ,  850  may be arranged at an insulation upper plate  270 . As the distance sensor  710  and the cooling fan module  810 ,  850  are arranged at the insulation upper plate  270 , heat in the cavity S may be prevented from being directly transferred to the distance sensor  710  and the cooling fan module  810 ,  850 . Therefore, the durability of the distance sensor  710  and the cooling fan module  810 ,  850  may be improved. 
     Referring to  FIG.  17   , a lighting through portion  273  may be provided in the insulation upper plate  270 . The lighting through portion  273  may be disposed at a location corresponding to the above-described lighting mounting part  165  of the inner upper plate  160 . The lighting fixture  790  may be arranged in the lighting mounting part  165  through the lighting through portion  273 . 
     A sensor mounting portion  274  may be provided at a portion of the insulation upper plate  270 , which is close to the lighting through portion  273 . The sensor mounting portion  274  may be provided at a front portion, which is close to the door  300 , of the insulation upper plate  270 . The distance sensor  710  may be mounted at the sensor mounting portion  274 . When the distance sensor  710  is arranged at the sensor mounting portion  274 , a distance sensing part  720  of the distance sensor  710  may face the center portion of the cavity S. The distance sensing part  720  may be exposed in a direction toward the center portion of the cavity S through the sensing hole  163  of the inner upper plate  160 . 
     A protection cover  276  (referring to  FIG.  28   ) may be provided at the insulation upper plate  270  to block electromagnetic wave introduced through a gap between a moving assembly  630  and a fixed assembly  640  to be described below. The protection cover  276  may surround an edge of a fan through portion  278   a ,  278   b  provided at a center portion of the insulation upper plate  270 . The protection cover  276  will be described in more detail below. 
     As shown in  FIG.  6   , the insulation upper plate  270  may have the fan through portion  278   a ,  278   b . The fan through portion  278   a ,  278   b  may be formed at a portion of the insulation upper plate  270 , which protrudes rearward more than the inner casing  100 . Therefore, the fan through portion  278   a ,  278   b  may be open to the outside space of the inner casing  100 . In the embodiment, the fan through portion  278   a ,  278   b  may be open rearward from the insulation rear plate  280  coupled to the inner casing  100 . 
     The fan through portion  278   a ,  278   b  may be open toward the third electric chamber ES 3 . The first cooling fan module  810  may be arranged in one portion of the fan through portion  278   a ,  278   b . The power supply unit  770  may be arranged below the fan through portion  278   a ,  278   b . Therefore, air discharged from the first cooling fan module  810  may be discharged to the power supply unit  770  through the fan through portion  278   a ,  278   b.    
     In the embodiment, the fan through portion  278   a ,  278   b  may include a first through portion  278   a  and a second through portion  278   b . The first through portion  278   a  and the second through portion  278   b  may be respectively formed at locations corresponding to a first drive blade  825   a  and a second drive blade  825   b  constituting the first cooling fan module  810 . The first through portion  278   a  may be open toward a high voltage transformer  771  of the power supply unit  770 , and the second through portion  278   b  may be formed to be closer to a center portion of the third electric chamber ES 3  than the first through portion  278   a.    
     As shown in  FIG.  2   , the insulation rear plate  280  may be arranged between the inner rear plate  120  and the outer rear plate  220 . The insulation rear plate  280  is coupled to the inner rear plate  120 , and the third electric chamber ES 3  may be provided between the insulation rear plate  280  and the outer rear plate  220 . The insulation rear plate  280  may supply heat transferred from the inner rear plate  120  to the outer rear plate  220  like the insulation upper plate  270 . 
     As shown in  FIGS.  3  and  4   , the insulation rear plate  280  may have a rectangular plate shape (not limited thereto). A first surface of the insulation rear plate  280  may face the inner rear plate  120  and a second surface of the insulation rear plate  280  may face the outer rear plate  220 . The insulation rear plate  280  may be coupled to the inner rear plate  120 , and the power supply unit  770  may be arranged on the surface  281  of the insulation rear plate  280  (referring to  FIG.  18   ), the surface facing the outer rear plate  220 . Therefore, the insulation rear plate  280  may prevent or substantially reduce heat of the inner upper plate  160  from being directly transferred to the power supply unit  770 . 
     A spacer  282  may be arranged at a lower portion of the insulation rear plate  280 . The spacer  282  may protrude downward from the insulation rear plate  280 . The spacer  282  may be provided to space a lower end of the insulation rear plate  280  from the outer lower plate  250 . As shown in  FIG.  6   , air may flow into an empty portion between the lower end of the insulation rear plate  280  and the outer lower plate  250 , the empty portion being generated by the spacer  282 . Reference numeral  283  may represent a ventilation part through which air flows. The spacer  282  may be integrally formed with the insulation rear plate  280  or be a separate object assembled to the insulation rear plate  280 . 
     As shown in  FIG.  1   , the door  300  may be provided at front of the outer front plate  240 . The door  300  may open and close the cavity S. The door  300  may be swung by coupling the hinge assembly provided at a lower portion of the door  300  to a hinge holder  253  (referring to  FIG.  2   ) provided at the outer lower plate  250 . A penetration part  310  of the door  300  may be made of a transparent or translucent material so that a user can observe the cavity S from the outside space. Reference numeral  320  may represent a handle of the door  300 . 
     Left and right frames  330  may be coupled to side surfaces of the door  300 , and a lower frame  340  may be coupled to a lower end of the door  300 . Although not shown in the drawing, an upper frame may be provided to an upper portion of the door  300 . The frames may surround the penetration part  310  to form the frame of the door  300 . 
     The display module  350  may be arranged at an upper portion of the door  300 . The display module  350  may indicate a cooking state of the cooking appliance, and may include an interface for the user to manipulate the cooking appliance. The air inlet part  242  is arranged below the display module  350 , thereby preventing the display module  350  from interfering with the air inlet part  242 . 
     The first heat source module  400  may be arranged at the inner casing  100 . The first heat source module  400  may generate microwaves to cook the food. In the embodiment, the first heat source module  400  may be arranged at the pair of inner side plates  110  of the inner casing  100 . Referring to  FIG.  2   , the first heat source module  400  may be arranged at an outer portion of a left one of the pair of inner side plates  110 . 
     Since a magnetron  410  of the first heat source module  400  is arranged at the insulation rear plate  280 , the first heat source module  400  may be arranged at both the fourth electric chamber ES 4  and the fifth electric chamber ES 5 . Otherwise, the first heat source module  400  may be arranged at an outer portion of a right one of the pair of inner side plates  110 , or at an outer portion of the inner rear plate  120 . 
     Referring to  FIGS.  3  and  4   , the first heat source module  400  may include the magnetron  410  oscillating microwaves and a wave guide  420  guiding the microwaves oscillated from the magnetron  410  to the cavity S. Herein, the magnetron  410  may be mounted to a portion of the wave guide  420 , the portion protruding from the inner side plate  110 . 
     Referring to  FIGS.  15  and  16   , the wave guide  420  may have a guide space  421  that is open toward the inner side plate  110 , and the wave guide  420  may include a stirrer (not shown) to diffusely reflect microwaves transferred through the wave guide  420 . Reference numeral  430  represents a stirrer motor for rotation of the stirrer, and Reference numeral  431  represents a bracket for mounting the stirrer motor. 
     As shown in  FIG.  16   , a mounting plate  415  may be coupled to the wave guide  420 . The magnetron  410  may be mounted to the mounting plate  415 . The microwaves generated by the magnetron  410  may be transferred to the cavity S through the wave guide  420 . Reference numeral  450  is a cover coupled to the inner side plate  110  facing the cavity S, and the cover  450  may prevent the stirrer to be damaged. 
     Next, the second heat source module  500  will be described. The second heat source module  500  may be arranged at a bottom surface of the casing  100 ,  200 . The second heat source module  500  may heat food rapidly by induction heating method. The second heat source module  500  may be fixed on the bottom surface of the casing  100 ,  200 . As shown in  FIGS.  2  and  3   , the second heat source module  500  may form the bottom of the inner casing  100 . In other words, an upper portion of the second heat source module  500  may be exposed to the cavity S. 
     The second heat source module  500  may be controlled by the main controller  700 . The main controller  700  may control the second heat source module  500  in an inverter manner, and may control power of the second heat source module  500  linearly. Therefore, detailed control of the second heat source module  500  may be realized. 
     As shown in  FIG.  5   , a bowl B may be provided on the second heat source module  500  to put food thereon. A bottom portion of the bowl B may be made of a metal material having magnetism such as stainless steel sheet. When the bowl B is heated by a magnetic field generated by a working coil  570 , food or items in the bowl B may be heated together. 
     As shown in  FIG.  1   , a cover plate  580  may be provided at a center portion of the second heat source module  500 , and the bowl B may be placed on the cover plate  580 . The cover plate  580  may be arranged at a location facing a heating unit  610  (referring to  FIG.  28   ) constituting the third heat source module  600 . Therefore, a lower portion of the food may be heated by the second heat source module  500 , and an upper portion of the food may be heated by the third heat source module  600 . 
       FIGS.  19  to  22    show the structure of the second heat source module  500 . As shown in the drawings, the second heat source module  500  may include a base plate  510  and a supporter  520 . A mounting bracket  530 , a shield filter  540 , and a coil assembly  550  may be arranged between the base plate  510  and the supporter  520 . This coupling structure between the parts will be described in more detail below. 
     The base plate  510  may have approximately a rectangular plate shape (not limited thereto) having an empty base hole  512  at a center portion thereof, and may be regarded as a lower plate of the inner casing  100  forming the bottom surface of the cavity S. The cover plate  580  may be arranged at the base hole  512 , and the cover plate  580  may be composed of a non-magnetic substance. The base plate  510  may be made of a metal material of a magnetic substance. The base plate  510  composed of a magnetic substance may prevent or substantially reduce the microwaves generated by the first heat source module  400  from reaching the working coil  570 . 
     As shown in  FIG.  20   , the supporter  520  may have approximately a circular plate shape (not limited thereto), and the supporter  520  may have a plurality of heat dissipation slits  525  for heat dissipation. An upper surface  521  of the supporter  520  may include a coil base  560  and the working coil  570  constituting the coil assembly  550 . The supporter  520  may function to shield electromagnetic interference (EMI). 
       FIG.  21    is a section view showing the inner structure of the second heat source module  500  according to an embodiment of the invention. The mounting bracket  530  may be arranged between the base plate  510  and the supporter  520 . The mounting bracket  530  may be coupled to both the base plate  510  and the supporter  520  to connect the base plate  510  to the supporter  520 . In the embodiment, the base plate  510  and the mounting bracket  530  are coupled to each other by welding, and the mounting bracket  530  and the supporter  520  may be coupled to each other by screwing. According to another embodiment, the base plate  510  and the supporter  520  may be coupled to each other by screwing, and the mounting bracket  530  and the supporter  520  may be coupled to each other by welding. 
     Herein, the supporter  520  and the coil base  560  may also be coupled to each other by screwing. Accordingly, the coil assembly  550  may be fixed to the base plate  510  with the mounting bracket  530  as a medium as well as to the supporter  520 . Therefore, both upper portion and lower portion of the coil assembly  550  may be securely fixed. 
     The base plate  510  may have a plurality of uneven structures. The uneven structures may be provided to be coupled to the mounting bracket  530 , the shield filter  540 , and the coil base  560 . In the embodiment, the shield filter  540  may be arranged between the uneven structures of the base plate  510  and the coil base  560 . The shield filter  540  may be securely fixed between the uneven structures and the coil base  560 . 
     As shown in  FIGS.  21  and  22   , a filter cover portion  513  may be provided at a location adjacent to an edge of the base hole  512 . The filter cover portion  513  may cover a part of an edge of the shield filter  540 . An edge of the shield filter  540  may be compressed between the filter cover portion  513  and a filter supporter  561  of the coil base  560 . Therefore, the microwaves generated by the first heat source module  400  may be prevented from leaking toward the working coil  570  through a gap between the shield filter  540  and the coil base  560 . 
     A depressed portion  514  may be provided at an outer portion of the filter cover portion  513 . The depressed portion  514  is a portion depressed downward from the base plate  510 , and may be formed in a circular shape surrounding the filter cover portion  513 . A first inclined portion  513   a  may be formed at a portion from the filter cover portion  513  to the depressed portion  514 . The first inclined portion  513   a  may be formed to face a second inclined portion  561   a  of the coil base  560  to be described below. 
     Herein, the first inclined portion  513   a  and the second inclined portion  561   a  may reduce a distance between the base plate  510  and the coil base  560 . Accordingly, the base plate  510  and the coil base  560  may be aligned in an X-axis and a Y-axis, and the microwaves generated by the first heat source module  400  may be prevented from leaking through the gap between a gap between the base plate  510  and the coil base  560 . 
     Furthermore, the first inclined portion  513   a  may press against the edge portion of the shield filter  540 . When the first inclined portion  513   a  presses against the edge portion of the shield filter  540  downward, i.e., in a direction of arrow in  FIG.  21   , the shield filter  540  may be fixed in the x-axis or the Y-axis. Therefore, the shield filter  540  may be securely fixed without the need for a fastener such as a screw. 
     A seating portion  515  may be provided at the opposite side of the filter cover portion  513  with the depressed portion  514  located between the filter cover portion  513  and the seating portion  515 . The cover plate  580  may be arranged at an upper surface of the seating portion  515 . A seating fence  516  may be provided at an outer portion of the seating portion  515  while surrounding the seating portion  515 . The seating fence  516  may protrude upward, and may cover an edge of the cover plate  580 . Therefore, the cover plate  580  may be aligned inside the seating fence  516 . 
     Herein, as shown in  FIG.  22   , the seating portion  515  may be formed above the filter cover portion  513 . Accordingly, the cover plate  580  does not reach the filter cover portion  513 , but may reach the seating portion  515 . Furthermore, the cover plate  580  and the shield filter  540  may be spaced apart from each other. Accordingly, when the second heat source module  500  is operated, vibrations generated in the cover plate  580  may be reduced. 
     As shown in  FIG.  21   , the plurality of heat dissipation slits  525  for heat dissipation may be provided in the supporter  520 . The supporter  520  may have a first fastening hole  526  provided to couple the supporter  520  to the coil base  560 . When the fastener, such as a screw (not shown), is coupled to the first fastening hole  526 , the supporter  520  and the coil base  560  may be assembled together. 
     The supporter  520  may have a guide protrusion  527 . The guide protrusion  527  may be fitted into a guide hole  537  formed in the mounting bracket  530 . When the guide protrusion  527  is fitted into the supporter  520 , an initial location between the supporter  520  and the mounting bracket  530  may be aligned. Accordingly, when a second fastening hole  528  of the supporter  520  may be connected to a bracket fastening hole  538  of the mounting bracket  530 , the fastener (not shown), such as a bolt or a screw, may be filled into the holes. 
     The mounting bracket  530  may connect the base plate  510  to the supporter  520 . The mounting bracket  530  may have approximately a circular frame shape (not limited thereto), and a bracket through portion  532  may be formed in a center portion of the mounting bracket  530 . As shown in  FIG.  19   , the mounting bracket  530  may include a bracket lower portion  531  having a relatively wider diameter, a bracket upper portion  534  having a relatively narrower diameter. Thus, the bracket lower portion  531  and the bracket upper portion  534  may be connected to each other by an inclined-shape bracket connection portion  533 . 
     Herein, since the mounting bracket  530  is arranged between the base plate  510  and the supporter  520 , the base plate  510  may be spaced apart from the supporter  520  by at least the height of the mounting bracket  530 . The coil assembly  550  may be arranged between the spacing between the base plate  510  and the supporter  520 . The height of the bracket connection portion  533  may be the height of the mounting bracket  530 . 
     In the embodiment, the mounting bracket  530  are provided as a separate object from the base plate  510  and the supporter  520 , but the mounting bracket  530  may be a part of the base plate  510  or the supporter  520 . In other words, the mounting bracket  530  may be a part of the base plate  510 , or a part of the supporter  520 . In this case, the mounting bracket  530 , which is a separate object, can be omitted. 
     As shown in  FIGS.  21  and  22   , the bracket upper portion  534  may be provided at a lower portion of the seating portion  515 , and the bracket upper portion  534  may be arranged between the seating fence  516  and the depressed portion  514 . The bracket upper portion  534  may be coupled to the base plate  510  by welding (not limited thereto). 
     The bracket connection portion  533  may have a bracket heat dissipation hole  535  for heat dissipation. The bracket heat dissipation hole  535  may be opened sideways. The bracket heat dissipation hole  535  may dissipate heat between the supporter  520  and the base plate  510 , and outside air may be introduced into the bracket heat dissipation hole  535  to cool the coil assembly  550 . 
     Meanwhile, the bracket lower portion  531  may be coupled to an edge of the supporter  520 . The bracket lower portion  531  may have the guide hole  537 , and the guide protrusion  527  of the supporter  520  described above may be fitted into the guide hole  537 . Reference numeral  538  may represent the bracket fastening hole  538  connected to the second fastening hole  528  of the supporter  520 . Therefore, the bracket lower portion  531  may be coupled to the supporter  520  by a screw, etc. 
     The shield filter  540  may be arranged between the cover plate  580  and the coil assembly  550 . The shield filter  540  may have an approximately circular plate structure, and may cover an upper portion of the working coil  570 . The shield filter  540  may prevent or substantially prevent microwaves generated from the first heat source module  400  from being transferred to the working coil  570 . The shield filter  540  may be composed of any one of graphite, graphene, carbon fabric, carbon paper, and carbon felt. 
     As described above, when the shield filter  540  is composed of any one of graphite, graphene, carbon fabric, carbon paper, and carbon felt, the shield filter  540  may have excellent microwave shield performance due to high conductivity. Furthermore, since the shield filter  540  may maintain heating by the second heat source module  500 , heating performance of the second heat source module  500  may be maximized. Furthermore, when the shield filter  540  is composed of any one of graphite, graphene, carbon fabric, carbon paper, and carbon felt, it is easy to emit heat increased by microwaves due to high thermal conductivity. 
     In the embodiment, the shield filter  540  may be formed by laminating graphite sheet and mica sheet together. Herein, the mica sheet may be relatively thicker than the graphite sheet. For example, when the thickness of the graphite sheet is 0.2 mm, the thickness of the mica sheet may be 1.0 mm. 
     The diameter of the shield filter  540  may be larger than the diameter of the working coil  570 , and may be smaller than the diameter of the cover plate  580  and the diameter of the supporter  520 . Accordingly, the shield filter  540  may completely cover an upper portion of the working coil  570 , thereby blocking the microwaves transferred to the working coil  570 . Conversely, the shield filter  540  may efficiently transmit the magnetic fields generated by the working coil  570  upward through the cover plate  580 . 
     The shield filter  540  may be fixed to the second heat source module  500  without a separate fastener. However, when a fastener is used, the microwaves may be introduced toward the working coil  570  through a hole for fastening the fastener, a screw thread, or the like to affect the working coil  570 . Furthermore, an electric field is concentrated to an edge of a hole or a sharp screw thread so that arc discharge may occur and a fire may occur. Therefore, a structure is applied to the embodiment to fix the shield filter  540  without a fastener. 
     The shield filter  540  may be pressed between the filter cover portion  513  of the base plate  510  and the filter supporter  561  of the coil base  560 . The filter cover portion  513  and the filter supporter  561  may press against the edge of the shield filter  540  and, more specifically, the filter cover portion  513  may be in surface-contact with an upper surface of the shield filter  540 , and the filter supporter  561  may be in surface-contact with a lower surface of the shield filter  540 . This surface-contact structure may reduce gaps between the shield filter  540 , the base plate  510 , and the coil base  560 , and may prevent or substantially prevent the microwaves from being introduced. 
     As shown in  FIG.  22   , the first inclined portion  513   a  provided in a portion where the filter cover portion  513  is connected to the depressed portion  514  and the second inclined portion  561   a  of the coil base  560  may face each other. Thus, a gap between the first inclined portion  513   a  and the second inclined portion  561   a  may be reduced as the gap is further away from the shield filter  540 . Accordingly, the first inclined portion  513   a  and the second inclined portion  561   a  may not only strongly press the edge of the shield filter  540  but also block a path through which the edge of the shield filter  540  is in contact with the outside space. 
     In other words, the first inclined portion  513   a  and the second inclined portion  561   a  may reduce the distance between the base plate  510  and the coil base  560 . Accordingly, the base plate  510  and the coil base  560  may be aligned in an X-axis and a Y-axis, and the microwaves generated by the first heat source module  400  may be prevented from leaking through the gap between a gap between the base plate  510  and the coil base  560 . Herein, the first inclined portion  513   a  may press against an end of the shield filter  540  in the direction of arrow {circle around (1)} in  FIG.  21   , and the shield filter  540  may be respectively fixed in the X-axis and the Y-axis. Therefore, even when a fastener, such as a screw, is not used, the shield filter  540  may be securely fixed. 
     Meanwhile,  FIG.  20    is a perspective view showing the structure of the coil assembly  550 . As shown, the coil base  560  of the coil assembly  550  may include an approximately circular base body  561 , and a plurality of coil guides  565  may be provided in the base body  561 . The coil guides  565  may be arranged in a structure composed of a plurality of concentric circles of different diameters. A coil mounting groove  566  may be depressed between the coil guides  565 , the working coil  570  may be coiled in the coil mounting groove  566 . Reference numeral  563  may represent a reinforcing rib for reinforcing the strength of the coil base  560 . 
     A fixed housing  577  may be provided at a center portion of the coil assembly  550 , and a first temperature sensor  578  may be arranged in the fixed housing  577 . The first temperature sensor  578  may measure the temperature of the second heat source module  500 . Based on the temperature of the second heat source module  500  measured by the first temperature sensor  578 , the user can adjust the temperature of the second heat source module  500 . Although not shown in the drawings, in order to increase the density of magnetic field generated by the working coil  570 , the coil assembly  550  may further include ferrite, which is a magnetic ceramic material having oxidized steel (Fe2O3) as a primary component. 
     The cover plate  580  may be arranged in the base hole  512  of the base plate  510 . The cover plate  580  may have an approximately circular plate shape (not limited thereto). The cover plate  580  may cover the base hole  512 , and may form an upper surface of the second heat source module  500  in a flat surface structure. The cover plate  580  may be made of a non-metallic substance so that the magnetic fields of the working coil  570  may pass through the cover plate  580 . The cover plate  580  may be made of a glass material having heat resistance against heat or the like (for example, ceramics glass). The cover plate  580  may dissipate heat of the shield filter  540 . 
     As shown in  FIGS.  23  to  26   , an assembly process of the second heat source module  500  will be described. First, as shown in  FIG.  23   , with the base plate  510  inverted, the mounting bracket  530  may be coupled to the base plate  510 . The mounting bracket  530  may be arranged around the base hole  512 . Referring to  FIG.  21   , the bracket upper portion  534  of the mounting bracket  530  may be laminated to the seating portion  515  of the base plate  510 . The bracket upper portion  534  and the seating portion  515  may be coupled to each other by welding, etc. 
     In this state, the shield filter  540  is coupled to the base plate  510  to block the base hole  512  of the base plate  510 . The shield filter  540  may be simply seated on the base plate  510 , and a fastening process by a tool or a fastener is not performed.  FIG.  24    is a view showing the shield filter  540  seated on the seating portion  515  of the base plate  510 . Herein, referring to  FIG.  21   , a location of the edge of the shield filter  540  may be guided by the depressed portion  514  of the base plate  510 . 
     The coil assembly  550  and the supporter  520  may be laminated on the shield filter  540 . The coil base  560  of the coil assembly  550  is larger than the shield filter  540 , the shield filter  540  may be blocked. Referring to  FIGS.  21  and  22   , the filter supporter  561  of the coil base  560  may be in surface-contact with the edge of the shield filter  540 . 
     In this state, the supporter  520  may be disposed on the coil assembly  550 , and the supporter  520  and the coil base  560  may be coupled to each other by a fastener, such as a screw, etc. Furthermore, the supporter  520  and the mounting bracket  530  may also be coupled to each other by a fastener, such as a screw, etc. Herein, since the mounting bracket  530  has been coupled to the base plate  510  first, the supporter  520  and the coil assembly  550  may also be coupled to the base plate  510  by a medium of the mounting bracket  530 . This state is shown in  FIG.  26   . 
     In this process, the shield filter  540  may be pressed between the base plate  510  and the coil base  560 . In other words, opposite surfaces of the shield filter  540  may be in surface-contact with the seating portion  515  and the filter supporter  561 , and may be securely fixed while being pressed without a separate fastener. 
     Next, the third heat source module  600  will be described with reference to  FIGS.  27  to  31   . The third heat source module  600  may be arranged at an upper portion of the casing  100 ,  200 . The third heat source module  600  may generate radiant heat inside the cavity S. Therefore, the third heat source module  600  may include a heating unit  610  (referring to  FIG.  28   ). The heating unit  610  may generate radiant heat in a downward direction, i.e., toward the cavity S, and may heat an upper portion of food. The heating unit  610  may be a graphite heater. The heating unit may serve as a kind of a broil heater, and the heating unit may be used as usage of grill using direct fire heat or radiant heat. 
     The third heat source module  600  may be fixed to the inner casing  100  or the outer casing  200 . In the embodiment, the third heat source module  600  may be fixed to the insulation upper plate  270 . The third heat source module  600  may be arranged in the first electric chamber ES 1 . The outer upper plate  230  may be arranged above the third heat source module  600 , so that the third heat source module  600  may be shielded. As shown in  FIG.  1   , the third heat source module  600  may be shielded by the outer upper plate  230 . 
     On the other hand, the third heat source module  600  may move toward to the bottom of the cavity S, i.e., the second heat source module  500 . The third heat source module  600  may include the moving assembly  630 , so that the heating unit  610  may move. In the embodiment, since the heating unit  610  may move in upward and downward directions, the heating unit  610  may be raised and lowered. 
     The third heat source module  600  may include the moving assembly  630  including and protecting the heating unit  610  and the fixed assembly  640  provided at the insulation upper plate  270  to control upward and downward movements of the moving assembly  630 . The third heat source module  600  may include a link assembly  650  provided at one portion of the moving assembly  630  to movably connect the moving assembly  630  to the fixed assembly  640 . Hereinbelow, the above structure will be described in more detail. 
     The moving assembly  630  may be provided separately from the inner casing  100  and the outer casing  200  to be vertically movable inside the cavity S. Preferably, the moving assembly  630  may be provided to surround a lateral portion of the heating unit  610 , so that heat of the heating unit  610  is concentrated downward without being emitted sideways. 
     The moving assembly  630  may have multiple levels of height. For example, the moving assembly  630  may have a first level at a highest location, a second level located at a middle location, and a third level at a lowest location. When the moving assembly  630  is located at the third level, heat transferred to the heating unit  610  may be strongest. The main controller  700  may adjust the height of the moving assembly  630  for each level. 
     The moving assembly  630  may include a heater housing  632  surrounding and protecting the heating unit  610 , and an insulating member  635  provided at one end of the heater housing  632  and preventing heat or electromagnetic waves. As shown, the heater housing  632  may have a square box shape. A vertical through hole is provided in the bottom surface of the heater housing  632  so that heat of the heating unit  610  may pass through the hole. 
     The heater housing  632  may move vertically by passing through a gap between a fixed frame  641 , which will be described below, and the protection cover  276 . Therefore, the heater housing  632  may be shaped in a square box open upward, and have a predetermined thickness. The thickness of four side surfaces of the heater housing  632  may be formed less than a size of the gap between the fixed frame  641  and the protection cover  276 . 
     The heater housing  632  may have a guide groove  633  selectively storing a fixed guide  642 , which will be described below. In other words, as shown in  FIG.  28   , the guide groove  633  may be formed in each of left and right surfaces of the heater housing  632  by penetrating the surface in a downward direction with a predetermined length. The guide groove  633  may store a frame coupling portion  643  of the fixed guide  642  when the moving assembly  630  is raised. 
     The insulating member  635  may have a rectangular frame shape as shown in the drawings. Preferably, lateral ends of the insulating member  635  may be formed to protrude outward than the lateral ends of the heater housing  632 . In other words, the exterior size of the insulating member  635  may be formed larger than the lateral size of the heater housing  632 , so that electromagnetic waves may be prevented from leaking outward through the gap between the fixed frame  641  and the protection cover  276  when the moving assembly  630  is raised. 
     The heating unit  610  may be provided inside the heater housing  632 . The heating unit  610  may have a transversally or longitudinally long shape, and preferably, a plurality of heating units  610  may be provided and installed in an inner lower end of the heater housing  632 . As shown in  FIG.  7   , the view shows total three heating units  610  arranged in the moving assembly  630 . 
     The three heating units  610  may be operated independently. In other words, among the three heating units  610 , any one or two heating units may be operated, or the three heating units  610  may be operated at the same time. The main controller  700  may control the number of operated heating units among the three heating units  610 , or control an operating time of the three heating units  610 , or control the height of the moving assembly  630  and the height of the heating units  610 . 
     Next, the fixed assembly  640  may be securely provided at an upper portion of the insulation upper plate  270 . The fixed assembly  640  may support the moving assembly  630  so that the moving assembly  630  may move in the upward and downward directions while being supported by an upper surface of the insulation upper plate  270 . The fixed assembly  640  may include a moving control means  670  to restrict the moving assembly  630  to move in the upward and downward directions by operation of the link assembly  650 . 
     The link assembly  650  may be provided at an upper portion of the moving assembly  630 . The link assembly  650  may include at least one link, and may guide the moving assembly  630  to move in the upward and downward directions while being connected to the fixed assembly  640 . Herein, upper and lower ends of the link assembly  650  may be rotatably connected to the fixed assembly  640  and the moving assembly  630 . 
     The insulation upper plate  270  may be regarded as a part of the fixed assembly  640 . The fixed assembly  640  may include the fixed frame  641  that is provided on the insulation upper plate  270  to support the moving control means  670 . 
     Herein, the fixed frame  641  may be provided to be spaced apart of the protection cover  276  of the insulation upper plate  270 . More specifically, the protection cover  276  may also have a rectangular shape like the insulation upper plate  270 , and the protection cover  276  may have a vertical through hole at a center portion thereof like the insulation upper plate  270  to form a rectangular frame shape. Accordingly, the moving assembly  630  may move in the upward and downward directions through such the insulation upper plate  270  and the central hole of the protection cover  276 . 
     The fixed frame  641  may have a rectangular shape smaller than the rectangular-shaped central hole of the protection cover  276 . Therefore, a predetermined gap may be provided between the fixed frame  641  and the protection cover  276 , and the heater housing  632  of the moving assembly  630 , which will be described in more detail below, may move in the upward and downward directions through the gap. 
     The fixed frame  641  may be securely provided on the insulation upper plate  270 . For this structure, the fixed guide  642  may be provided between the insulation upper plate  270  and the fixed frame  641 . The fixed guide  642  may have an approximately “∩”-like shape (view from the front) as shown in the drawings. Therefore, an upper end of the fixed guide  642  may be coupled to the fixed frame  641 , and a lower end of the fixed guide  642  may be fixed to the insulation upper plate  270  or the protection cover  276 . 
     Specifically, as shown in  FIG.  27   , the fixed guide  642  may include the frame coupling portion  643  coupled to the fixed frame  641 , and an upper coupling portion  644  fixed to the insulation upper plate  270  or the protection cover  276 . In the present disclosure, the upper coupling portion  644 , i.e., the lower end of the fixed guide  642 , is coupled to the upper surface of the insulation upper plate  270 . 
     The fixed assembly  640  may include a sliding rail  279  supporting a moving bracket  676  or a lead nut  673 , which will be described below, to be slidable. The sliding rail  279  may be provided with a transversally predetermined length on an upper surface of the fixed frame  641 . The moving bracket  676  or the lead nut  673  may be transversally movably installed on this sliding rail  279 . 
     The moving control means  670  may be provided on the fixed frame  641 . The moving control means  670  may include a motor  671  generating rotation power, a lead screw  672  provided at one portion of the motor  67  land rotated in conjunction with the rotation power generated by the motor  671 , and the lead nut  673  fastened to the lead screw  672  by screwing. 
     The motor  671  may generate rotation power and a stepping motor may be used as the motor  671  so as to perform precise rotation control. The stepping motor may supply forward and reverse rotation movements in response to a rotation angle by purse control. 
     As shown in the drawings, the lead screw  672  may be a fine cylinder of a predetermined length, of which an outer surface is formed in a male screw. Herein, the male screw of the lead screw  672  is coupled to the lead nut  673  having a female screw corresponding to the male screw. Therefore, when the lead screw  672  is rotated by power of the motor  671 , the lead nut  673  moves transversally along the lead screw  672 . As described above, the lead screw  672  and the lead nut  673  may function to change the forward and reverse rotation movements into a linear movement. 
     A connection coupling  674  may be provided between the motor  671  and the lead screw  672  to connect one end of the lead screw  672  to a motor shaft. In other words, as shown in  FIG.  27   , the connection coupling  674  may be provided between a right end of the lead screw  672  and the motor shaft protruding leftward from the motor  671 . 
     The motor  671  may be provided to a fixed bracket  675  securely mounted to the fixed assembly  640 , and the lead nut  673  may be mounted to the moving bracket  676  movably installed to the fixed assembly  640 . The moving bracket  676  may be movably provided above the fixed frame  641  to move closer to or farther from the fixed bracket  675 . 
     Specifically, the fixed frame  641  may be provided above the insulation upper plate  270  to be spaced apart therefrom by the fixed guide  642 , and a gap of predetermined size is formed between the fixed frame  641  and the protection cover  276 , thereby forming a moving path of the heater housing  632 , which will be described below. 
     When the lead screw  672  is rotated in response to rotation of the motor  671  mounted to the fixed bracket  675 , the lead nut  673  moves transversally, whereby the moving bracket  676  moves transversally along the sliding rail  279 . 
     Upper ends of a link of the link assembly  650  may be rotatably installed to the fixed bracket  675  and the moving bracket  676 . In other words, when left and right upper ends of an “X”-shaped link provided in the link assembly  650  are respectively connected to the fixed bracket  675  and the moving bracket  676 , the left and right upper ends of the “X”-shaped link may move closer to each other or farther from each other in response to leftward and rightward movements of the moving bracket  676 , so that the moving assembly  630  fixed to the lower end of the link assembly  650  may move in upward and downward directions. 
     Meanwhile, the link assembly  650  may have a structure including at least one link, and the upper end of the link assembly  650  may be rotatably connected to the fixed assembly  640  and the lower end thereof may be rotatably connected to the moving assembly  630 . 
     The link assembly  650  may include a pair of front links  651  and  652  and a pair of rear links  653  and  654  that are spaced apart from each other by a predetermined distance in a longitudinal direction. A link frame  655  coupled to the moving assembly  630  may be provided at lower ends of the front links  651  and  652  and the rear links  653  and  654 . 
     At least one of left and right lower ends of the front links  651  and  652  and at least one of left and right lower ends of the rear links  653  and  654  may be movably coupled to the link frame  655 . Specifically, the pair of front links  651  and  652  may be configured such that a front first link  651  and a front second link  652  formed in a “X”-shape may be coupled to each other to be rotatable on a center, in which the front first link  651  and the front second link  652  cross each other, as a rotation center. The pair of rear links  653  and  654  may be configured such that a rear first link  653  and a rear second link  654  formed in a “X”-shape may be coupled to each other to be rotatable on a center, in which the rear first link  653  and the rear second link  654  cross each other, as a rotation center. 
     The lower ends of the front first link  651  and the rear first link  653 , which are installed to be spaced apart from each other in the longitudinal direction by a predetermined distance, may be connected to each other by a connection link  658 . The lower ends of the front second link  652  and the rear second link  654  may be connected to each other by the connection link  658 . 
     At least one of the left and right lower ends of the front links  651  and  652  and at least one of the left and right lower ends of the rear links  653  and  654  may be movably coupled to the link frame  655 . In the embodiment, as shown in the drawing, the view shows a case in which the lower ends of the front first link  651  and the rear first link  653  are installed to be movable in a transverse direction of the link frame  655 . 
     Therefore, a first link protrusion hole  657  may be formed in a left half portion of the link frame  655 , so that lower end shafts of the front first link  651  and the rear first link  653  are inserted into the first link protrusion hole  657  to be movable in the transverse direction. 
     In  FIG.  29   , the moving assembly  630  is in the first location. In  FIG.  30   , the moving assembly  630  is in the second location. When the moving assembly  630  is in the second location, the heating units  610  are located closer to the food, so that the food may be heated up faster. As shown in  FIG.  30   , when the moving assembly  630  is in the second location, the fixed guide  642  and the motor  671  constituting the fixed assembly  640  may not be moved and fixed in initial locations. 
     Meanwhile, in  FIG.  31   , a recovery switch SW arranged at the insulation upper plate  270  is pressed and an ON state is activated. The recovery switch SW is provided to detect recovery of the moving assembly  630  to the first location. The recovery switch SW may be turned in the ON state by being pressed by the moving assembly  630  recovered to the first location, and in the ON state, the main controller  700  may know that the moving assembly  630  is recovered. 
     When the recovery switch SW is turned to the ON state, the main controller  700  may detect recovery of the moving assembly  630  to the first location and may stop the motor  671 . In other words, the main controller  700  may stop the motor  671  to prevent the moving assembly  630  from being raised above the first location. In the embodiment, the recovery switch SW may limit a rising height of the moving assembly  630 , and the number of rotation of the motor  671  may limit a lowering height of the moving assembly  630 . 
     The recovery switch SW is arranged at the insulation upper plate  270  or the fixed guide  642  so as to remain fixed regardless of movement of the moving assembly  630 . The moving assembly  630  may include an operation pin P pressing and operating the recovery switch SW. The operation pin P may be arranged at the moving assembly  630 , thereby being raised and lowered together with the moving assembly  630 . 
     Herein, the recovery switch SW may include an elastic drive part ED. The elastic drive part ED may be a part that is actually pressed by the operation pin P. When the operation pin P presses the elastic drive part ED, the elastic drive part ED may press the recovery switch SW. The operation pin P may have a pin shape of which an upper end is narrower than a lower end, so that a contact portion of the recovery switch SW may be precisely pressed. In the embodiment, the operation pin P may press a wide surface of the elastic drive part ED and the elastic drive part ED may press the recovery switch SW, so that stable driving may be secured. 
     Both the recovery switch SW and the elastic drive part ED may be provided at a switch bracket SB. The switch bracket SB may be arranged at the fixed assembly  640 . In the embodiment, the switch bracket SB may be arranged at the fixed guide  642  of the fixed assembly  640 . 
     As shown in  FIG.  30   , two recovery switches SW may be included in the third heat source module  600 . The pair of recovery switches SW may be arranged adjacent to the pair of fixed guides  642 , respectively. Even when any one of the pair of recovery switches SW is broken, but a remaining recovery switch SW is normally operated, recovering of the moving assembly  630  to the first location may be detected. It is understood that only one recovery switch SW may be provided. 
     Referring to  FIG.  32   , the cooking appliance may include the distance sensor  710 . The distance sensor  710  may detect the existence of the food, the thickness of the food, and/or the height of the food. The distance sensor  710  may measure the thickness or the height of the food, and the main controller  700  may separately control operation and temperature of the first heat source module  400 , the second heat source module  500 , or the third heat source module  600  on the basis of the measured information. Furthermore, the distance sensor  710  may measure the thickness or the height of the food, which is changed in response to cooking time, and the main controller  700  may control a remaining cooking time or temperature. The distance sensor  710  may be an infrared sensor. 
     The distance sensor  710  may be arranged at the insulation upper plate  270 . As shown in  FIG.  3   , the distance sensor  710  may be arranged at a front portion of the insulation upper plate  270 . The distance sensor  710  may be arranged at an upper portion of the insulation upper plate  270 , the upper portion being located close to the outer front plate  240 . When the distance sensor  710  is arranged at the front portion of the insulation upper plate  270 , air introduced from the outside space may pass through the distance sensor  710  first, so that the distance sensor  710  may be efficiently cooled. 
     The distance sensor  710  is preferably arranged at a center portion based on a transverse width of the insulation upper plate  270  to face the center portion of the cavity S. The inner upper plate  160  may be arranged below the insulation upper plate  270 , but the inner upper plate  160  may have the sensing hole  163 , so that the distance sensor  710  may sense the inside space of the cavity S through the sensing hole  163 . 
     As described above, the distance sensor  710  may be arranged at the insulation upper plate  270  so that heat of the cavity S may be prevented from being directly transferred to the distance sensor  710 . Therefore, the durability of the distance sensor  710  may be improved. 
       FIGS.  32  to  35    are views showing a structure of the distance sensor  710  according to an embodiment of the present disclosure. First, as shown in  FIG.  32   , the distance sensor  710  may be arranged at the sensor mounting portion  274  provided in the insulation upper plate  270 . The sensor mounting portion  274  may be formed by vertically penetrating the insulation upper plate  270 . A sensor housing  711  of the distance sensor  710  may be arranged at the sensor mounting portion  274 . 
     Herein, the insulation cover  718  of the distance sensor  710  may be disposed on a sensor seating end  274   a  provided in the sensor mounting portion  274 . A plurality of sensor seating ends  274   a  may be provided in the sensor mounting portion  274 , and the plurality of sensor seating end  274   a  may have a structure that is stepped in a direction in which the width of the sensor mounting portion  274  is narrowed. Accordingly, the insulation cover  718  may be prevented, by being caught by the sensor seating end  274   a , from falling downward. The sensor seating ends  274   a  may be provided at different surfaces of the sensor mounting portion  274 . 
     The distance sensor  710  may include the sensor housing  711  and the distance sensing part  720 . The sensor housing  711  may be fixed to the sensor mounting portion  274 , and the distance sensing part  720  may be fixed to the sensor housing  711 . An insulation cover  718  may be provided below the sensor housing  711 . The insulation cover  718  may be made of a glass material for sensing. The insulation cover  718  may be provided to prevent heat in the cavity S from being transferred to the distance sensor  710 . 
     As shown in  FIG.  33   , the distance sensor  710  may be arranged at the insulation upper plate  270 . The sensor housing  711  of the distance sensor  710  may be arranged at the sensor mounting portion  274  in a manner of covering the sensor mounting portion  274 . The sensor housing  711  may include a plurality of fixing hooks  713 . The fixing hooks  713  may grab and fix the distance sensing part  720 . In the embodiment, the sensor housing  711  may include four fixing hooks  713 . 
     As shown in  FIGS.  32  to  34   , the insulation upper plate  270  may have a locking groove  274   b , and a locking step  714  of the sensor housing  711  may be caught to the locking groove  274   b . While the sensor housing  711  is obliquely coupled to the sensor mounting portion  274  and the locking step  714  is caught to the locking groove  274   b  first, when the sensor housing  711  is rotated, the sensor housing  711  may completely cover the upper side of the sensor mounting portion  274 . 
     Herein, the sensor housing  711  may have a second housing coupling hole  716  corresponding to a first housing coupling hole  274   c  of the insulation upper plate  270 . When the second housing coupling hole  716  is connected to the first housing coupling hole  274   c , a fastener (not shown), such as a screw, may be fastened to the first housing coupling hole  274   c  and the second housing coupling hole  716 . The second housing coupling hole  716  may be coupled to the opposite side of the locking step  714 . 
     In  FIG.  34   , both the distance sensing part  720  and the insulation cover  718  are disassembled from the sensor housing  711  of the distance sensor  710 . As described above, the insulation cover  718  is first provided on the sensor seating end  274   a  of the sensor mounting portion  274 , and then the assembly of the sensor housing  711  and the distance sensing part  720  may be assembled on the insulation cover  718  and the sensor seating end  274   a.    
     As shown in  FIG.  35   , the distance sensing part  720  arranged at the sensor housing  711  may be arranged in an inclined direction. Specifically, a sensing device  725  provided in the distance sensing part  720  may face in the inclined direction. Referring to  FIG.  35   , the sensing device  725  is arranged to face the left lower side. Therefore, the sensing device  725  may face the center portion of the cavity S. For example, as shown in  FIG.  7   , the distance sensor  710  may be mounted to be inclined toward the center portion of the cavity S. 
     Next, referring to  FIGS.  36  to  42   , the camera module  730  will be described according to an embodiment of the present disclosure. The camera module  730  may be provided to observe the inside space of the cavity S. The camera module  730  may allow the user to observe the food in the cavity S in real time, and the main controller  700  may analyze images recorded by the camera module  730  to control proper cooking temperature and time. 
     The camera module  730  may be arranged at the camera mounting part  128  provided in the inner rear plate  120 . As shown in  FIG.  36   , the camera mounting part  128  may protrude rearward from the inner rear plate  120 . On the other hand, an insulation space  128   c  (referring to  FIG.  41   ) recessed from the camera mounting part  128  may be formed inside the cavity S. This recessed insulation space  128   c  may provide an angle of view that may allow a camera sensor  745  of the camera module  730  to film wide the inside space of the cavity S. Alternately, the insulation space  128   c  may serve as a kind of an insulation space to prevent the camera sensor  745  from being damaged. 
     An upper portion of the camera mounting part  128  may have an inclined structure. The camera module  730  may be arranged at an inclined flat surface  128   a  of the camera mounting part  128 . The camera sensor  745  may be arranged in the inclined direction, and may face the center portion of the cavity S. 
     The flat surface  128   a  of the camera mounting part  128  may have a filming hole  128   b . The camera sensor  745  may be exposed inward of the cavity S through the filming hole  128   b . Therefore, the center of the camera sensor  745  may need to be aligned on the filming hole  128   b . Accordingly, the flat surface  128   a  of the camera mounting part  128  may have a plurality of housing fixing holes  129   a  and  129   b . The housing fixing holes  129   a  and  129   b  may include the first fixing hole  129   a  and a second fixing hole  129   b , and the camera module  730  may be fixed to the first and second fixing holes. 
     Specifically, based on the filming hole  128   b , the first fixing hole  129   a  may be formed at one side of the filming hole  128   b  and the second fixing hole  129   b  may be formed at the opposite side thereof. In the embodiment, the second fixing hole  129   b  may include two holes, thereby reducing the vertical clearance. 
     The camera module  730  may include a camera housing  731 , and a camera substrate  740  mounted to the camera housing  731 . The camera sensor  745  may be embedded in the camera substrate  740 . After the camera substrate  740  is assembled to the camera housing  731  first, the camera module  730  may be mounted to the flat surface  128   a  of the camera mounting part  128 . In  FIG.  37   , the camera module  730  is mounted to the flat surface  128   a  of the camera mounting part  128 . For reference, both the camera substrate  740  and the camera sensor  745  may be regarded as one camera sensor. 
     In  FIG.  38   , the camera module  730  is shown as being disassembled. As shown in the drawing, the camera housing  731  may have an approximately hexahedron shape that may be extended long in the transverse direction. The camera housing  731  may have a substrate mounting space  732   a  in which the camera substrate  740  may be arranged. The substrate mounting space  732   a  may be formed deeply than the thickness of the camera substrate  740 . 
     The substrate mounting space  732   a  may have a lens exposing hole  732  that may expose a lens of the camera sensor  745 . The lens exposing hole  732  may be open toward the inside space of the cavity S. The lens exposing hole  732  may overlap with the filming hole  128   b  of the flat surface  128   a  to form a continuous hole. For reference, in  FIG.  8   , the camera sensor  745  is exposed toward the inside space of the cavity S. 
     The camera housing  731  may include a substrate holding hook  733 . The substrate holding hook  733  may be provided to hook an edge of the camera substrate  740  to fix the camera substrate  740 . The substrate holding hook  733  may protrude from an edge of the camera housing. In the embodiment, total four substrate holding hooks  733  are provided in the camera housing  731 , and three or five substrate holding hooks  733  may be provided. 
     As shown in  FIG.  39   , the camera housing  731  may include camera mounting hooks  734   a  and  734   b  at the opposite side of the substrate mounting space  732   a . The camera mounting hooks  734   a  and  734   b  may include a first mounting hook  734   a  and a second mounting hook  734   b  respectively provided at left and right portions of the camera housing  731 . The first mounting hook  734   a  and the second mounting hook  734   b  may be respectively hooked by the first fixing hole  129   a  and the second fixing holes  129   b  provided in the flat surface  128   a . Herein, the second mounting hook  734   b  may include two second mounting hooks to correspond to the second fixing holes  129   b , thereby reducing the vertical clearance of the camera module  730 .  FIG.  40    is a view showing the first mounting hook  734   a  and the second mounting hook  734   b  respectively fixed to the first fixing hole  129   a  and the second fixing holes  129   b.    
     The camera housing  731  may include an elastic arm  735 . The elastic arm  735  may have a cantilever shape protruding from the camera housing  731  toward the flat surface  128   a . In the embodiment, the camera housing  731  may include a pair of elastic arms  735 . The elastic arms  735  may be elastically deformed when the camera housing  731  is mounted to the camera mounting part  128 , and may press against the flat surface  128   a . In this state, the elastic arms  735  is in strong and close contact with the flat surface  128   a , and even when vibrations are generate in an operation process of the cooking appliance, the camera module  730  may remain solidly fixed. In  FIG.  41   , the elastic arms  735  is in close contact with the flat surface  128   a.    
     The pair of elastic arms  735  may be provided around the lens exposing hole  732 . When the first mounting hook  734   a  and the second mounting hook  734   b  are arranged at left and right portions based on the lens exposing hole  732 , the pair of elastic arms  735  may be arranged in the vertical direction based on the lens exposing hole  732 . Accordingly, the camera module  730  may be securely fixed to the camera mounting part  128  in both the transverse direction and the vertical direction. Furthermore, since the pair of elastic arms  735  is elastically supported by the flat surface  128   a , the camera module  730  may be fixed without the clearance in the longitudinal direction. 
     As shown in  FIG.  41   , the camera mounting part  128  may include a camera cover  738 . In order to allow the camera sensor  745  to record or film the inside space of the cavity S, the camera cover  738  may be made of a transparent or translucent material. The camera cover  738  may be arranged at front of the camera module  730 , and may prevent the camera sensor  745  from being damaged by heat in the cavity S. The camera cover  738  may be arranged at the opposite side of the flat surface  128   a , but in the embodiment, the camera cover  738  may shield the recessed insulation space  128   c.    
     Referring to  FIG.  7   , in the embodiment, the camera module  730  may be arranged to face the center portion of the cavity S. Specifically, the lens of the camera module  730  may be arranged to face a center portion of a bottom surface of the cavity S. Since the food may be arranged at the center portion of the bottom surface of the cavity S, the lens of the camera module  730  may be preferably arranged to face the center portion of the bottom surface of the cavity S. 
     Next, referring to  FIG.  43   , a humidity sensing module  750  and a second temperature sensor  760  will be described. The humidity sensing module  750  may detect the amount of moisture in the cavity S, i.e., humidity, and transmit the information to the main controller  700 . The humidity sensing module  750  may include a humidity sensor detecting the humidity in the cavity S, and a signal converter converting a humidity detection signal of the humidity sensor into a digital signal, and a signal transmission module transmitting the humidity detection signal to the main controller  700 . 
     Herein, the humidity sensing module  750  may be mounted by penetrating from the inside portion to the outside portion of an exhaust duct  940 , which will be described below, thereby detecting the humidity in the cavity S. The exhaust duct  940  is a portion through which air in the cavity S is discharged. Therefore, the humidity sensing module  750  may be arranged in the exhaust duct  940  and may precisely measure the humidity in the cavity S. In the embodiment, the humidity sensing module  750  may be arranged at a position facing the outlet port  125  of the inner side plate  110 , thereby increasing the sensing precision. 
     The exhaust duct  940  may include the second temperature sensor  760 . The second temperature sensor  760  may measure the temperature in the cavity S. The second temperature sensor  760  may be arranged in the exhaust duct  940  and may precisely measure the temperature in the cavity S. The above-described first temperature sensor  578  may measure the temperature of the second heat source module  500 , and the second temperature sensor  760  may measure the temperature in the cavity S. The main controller  700  may control the first heat source module  400 , the second heat source module  500 , or the third heat source module  600  on the basis of the temperature measured by the second temperature sensor  760 . 
     Meanwhile, although not shown, the exhaust duct  940  may include a temperature block switch. The temperature block switch may be a safety switch that may cuts off the power when the temperature in the cavity S exceeds a preset temperature. Herein, instead of the second temperature sensor  760 , the temperature block switch may be arranged. 
     Furthermore, an additional third temperature sensor (not shown) may be arranged at the first electric chamber ES 1 . The third temperature sensor may be printed on the insulation upper plate  270  or the inner upper plate  160 . The third temperature sensor may adopt any one of a negative temperature coefficient (NTC) type, in which a resistance value is reduced when the temperature is increased, and a positive temperature coefficient (PTC) type in which a resistance value is increased when the temperature is increased. 
     Referring to  FIGS.  6  and  18   , the cooking appliance may include the power supply unit  770 . The power supply unit  770  may serve to be supplied with external power and transfer the power to the internal parts of the cooking appliance. The power supply unit  770  may include the high voltage transformer  771 , a high voltage capacitor  773 , and a fuse  775 . The components constituting the power supply unit  770  are only examples, and additional components may be provided or some parts may be omitted. 
     The high voltage transformer  771  may serve to apply high pressure a high voltage current to the magnetron  410 . For example, the high voltage transformer  771  may be a part provided to boost the household voltage, which is usually 100-220V, to a high voltage. Furthermore, the high voltage transformer  771  may supply power to the working coil  570  of the second heat source module  500  or the heating units  610  of the third heat source module  600 . In the drawing, a busbar or a wire harness, which is provided to connect the high voltage transformer  771 , the magnetron  410 , etc. to each other, is not shown. 
     In the embodiment, the power supply unit  770  may be arranged on a surface  281  of the insulation rear plate  280 . The insulation rear plate  280  may be coupled to the inner rear plate  120 , and may prevent heat of the inner rear plate  120  from being directly transferred to the power supply unit  770 . As shown in  FIG.  18   , the insulation rear plate  280  may have an approximately rectangular plate shape, and may include a camera avoidance hole  288  preventing interference between the insulation rear plate  280  and the camera module  730 . 
     The high voltage transformer  771  may be fixed to a rear surface  281   a  of the insulation rear plate  280 , and the high voltage capacitor  773  may be mounted on the rear surface  281   a  of the insulation rear plate  280  by a separate capacitor bracket  774 . In the embodiment, the high voltage transformer  771  may be arranged at a right side portion based on the center of the insulation rear plate  280 . Specifically, as shown in  FIG.  10   , the high voltage transformer  771  may be arranged at a lower portion of the second cooling fan module  850 . 
     As shown in  FIG.  32   , the lighting fixture  790  may be arranged on the inner upper plate  160 . The lighting fixture  790  may be mounted on the lighting mounting part  165  of the inner upper plate  160  through the lighting through portion  273  of the insulation upper plate  270 . The lighting mounting part  165  may be formed in an inclined direction, and a lighting hole  165   a  may be provided at a center portion of the lighting mounting part  165 . Light emitted from a light source of the lighting fixture  790  may pass through lighting hole  165   a  to the cavity S. 
     The lighting fixture  790  may include a lighting housing  791  and a lighting substrate  795 . The lighting housing  791  may include a lighting hook  793  to fix the lighting substrate  795 . In the embodiment, the lighting fixture  790  may be directly mounted on the inner upper plate  160  without a separate insulation cover. 
     As shown in  FIG.  2   , the cooking appliance may include the cooling fan module  810 ,  850 . The cooling fan module  810 ,  850  may cool the cooking appliance, suction external air and supply the air into the cavity S. The cooling fan module  810 ,  850  may suction air outside the cooking appliance and discharge air cooling the inside space of the cooking appliance to the outside space. In the embodiment, the cooling fan module  810 ,  850  may include the first cooling fan module  810  and the second cooling fan module  850 . Both the first cooling fan module  810  and the second cooling fan module  850  may be arranged at positions closer to an upper portion of the cavity S than a lower portion thereof. 
     Both the first cooling fan module  810  and the second cooling fan module  850  may be arranged on the insulation upper plate  270 . Herein, the first cooling fan module  810  and the second cooling fan module  850  may be arranged around the third heat source module  600  with the third heat source module  600  as the center. The cooling fan modules  810  and  850  arranged as described above may cool the third heat source module  600  in various directions. 
     The first cooling fan module  810  and the second cooling fan module  850  may be arranged in a direction orthogonal to each other. The cooling fan modules  810  and  850  arranged as described above may form a continuous flow path through which air flows. Referring to  FIG.  9   , the second cooling fan module  850  may suction air from the front side of the cooking appliance (lower side in  FIG.  9   ). A portion of the suctioned air may be transferred to the second cooling fan module  850  (arrow {circle around (3)}), and a portion of the suctioned air may be introduced toward the first cooling fan module  810  (arrow {circle around (2)}). In other words, the second cooling fan module  850  may guide the external air to be suctioned toward the first cooling fan module  810 . 
     Furthermore, the first cooling fan module  810  and the second cooling fan module  850  may respectively discharge air toward different surfaces of the inner casing  100 . The first cooling fan module  810  may discharge air toward a rear surface of the inner casing  100 , more specifically, toward the third electric chamber ES 3 . The second cooling fan module  850  may discharge air toward a side surface of the inner casing  100 , more specifically, toward the fifth electric chamber ES 5 . The air may meet the second electric chamber ES 2  and then be discharged to the outside space through the air outlet part  243 . 
       FIG.  17    is a view showing the first cooling fan module  810  according to an embodiment of the present disclosure. The first cooling fan module  810  may be arranged on the insulation upper plate  270 . The first cooling fan module  810  may be mounted to a fan plate  811 . The fan plate  811  may be attached to the insulation upper plate  270 , and the first cooling fan module  810  may be mounted to the fan plate  811 . The fan plate  811  may be laminated on the insulation upper plate  270 . The fan plate  811  may be omitted or may be provided integrally with the insulation upper plate  270 . 
     Herein, the fan plate  811  may have a plate hole to allow air discharged from the first cooling fan module  810  to pass through the hole. The plate hole may be connected to the first through portion  278   a  provide at the insulation upper plate  270  and the second through portion  278   b . For this structure, the plate hole may include a first plate hole  812   a  connected to the first through portion  278   a  and a second plate hole  812   b  connected to the second through portion  278   b.    
     The fan plate  811  may include a first fan bracket  815 . The first cooling fan module  810  may be mounted to the insulation upper plate  270  via the first fan bracket  815 . In the embodiment, a pair of first fan brackets  815  may be arranged to be spaced apart from each other, and the pair of first fan brackets  815  may be respectively coupled to a first drive housing  817   a  and a second drive housing  817   b.    
     Any one of the pair of first fan brackets  815  may include a first fan motor  820 . The first fan motor  820  may be connected to a shaft (not shown), and a pair of first fan blades  825   a  and  825   b  may be coupled to the shaft. The shaft may be extended in opposite sides from the first fan motor  820 , and the pair of first fan blades  825   a  and  825   b  may be coupled to opposite portions of the shaft.  FIG.  17    shows only the right first drive blade  825   a  among the pair of first fan blades  825   a  and  825   b , and  FIG.  12    showing the cooking appliance from the left shows the second drive blade  825   b.    
     The pair of first fan blades  825   a  and  825   b  may discharge air in a downward direction, i.e., in a direction of gravity. As shown in  FIG.  10   , two air streams may be discharged downward from the first cooling fan module  810 . The two air streams may be respectively discharged toward the third electric chamber ES 3 . The third electric chamber ES 3  may accommodate the high voltage transformer  771  of the power supply unit  770  and the magnetron  410  of the first heat source module  400 . Therefore, the high voltage transformer  771  and the magnetron  410  may be cooled by the first cooling fan module  810 . 
     Specifically, the magnetron  410  constituting the first heat source module  400  may be arranged below the first drive housing  817   a , and the high voltage transformer  771  constituting the power supply unit  770  may be arranged below the second drive housing  817   b . Therefore, the first cooling fan module  810  may cool both the power supply unit  770  and the first heat source module  400 . 
     Furthermore, air discharged from the first cooling fan module  810  may pass through the third electric chamber ES 3 , and move downward and then be introduced into the second electric chamber ES 2 . In  FIG.  12   , air discharged from the first cooling fan module  810  may move downward (direction of arrow {circle around (1)}) and then move forward (direction of arrow {circle around (2)}). In this process, the second heat source module  500  may be cooled together. 
     Next,  FIG.  44    is a view showing the second cooling fan module  850  according to an embodiment of the present disclosure. The second cooling fan module  850  may cool the cooking appliance like the first cooling fan module  810 , and may efficiently supply external air into the cavity S. In the structure of the second cooling fan module  850 , the second cooling fan module  850  may include a second fan casing  852  forming a frame, a second fan bracket  855  mounted to the second fan casing  852 , and a second fan motor  860 . 
     Referring to  FIG.  5   , the second fan casing  852  may be mounted to the insulation upper plate  270 . Herein, a separate guide fence GF may be vertically provided on the insulation upper plate  270 , and the second fan casing  852  may be mounted to the guide fence GF. The guide fence GF may have an approximately plate shaped structure. The guide fence GF may be arranged in a longitudinal direction, i.e., a depth direction of the cavity S. 
     Herein, the guide fence GF may guide a flow of air introduced into the upper portion of the cooking appliance, i.e., into the first electric chamber ES 1 . As shown in  FIG.  9   , an air flow path may be provided between the heater housing  632  and the guide fence GF. When the first cooling fan module  810  is operated, air may be introduced toward the first cooling fan module  810  (in direction of arrow {circle around (2)}) through the air flow path. 
     In other words, the guide fence GF to which the second cooling fan module  850  is mounted may provide a separate air flow path partitioned from the air flow path suctioned toward the second cooling fan module  850  (direction of arrow {circle around (1)}). Air suctioned toward the first cooling fan module  810  (direction of arrow {circle around (2)}) may cool the third heat source module  600  in the suctioning process. 
     Herein, when the third heat source module  600  is in the first location (referring to  FIG.  29   ), both the first cooling fan module  810  and the second cooling fan module  850  may cool the periphery of the heater housing  632 . When the third heat source module  600  is in the second location (referring to  FIG.  30   ), both the first cooling fan module  810  and the second cooling fan module  850  may cool the third heat source module  600  throughout while passing through an upper portion of the third heat source module  600 . 
     As shown in  FIG.  44   , the second fan casing  852  may include a bracket mounting portion  852   a  to which the second fan bracket  855  is mounted. Based on the bracket mounting portion  852   a , a housing mounting portion  852   b  at which a second fan housing  857  is arranged is arranged at one portion, and a motor mounting portion  852   c  to which the second fan motor  860  is mounted may be arranged at the opposite portion. The second fan housing  857  may be arranged closer to the door  300  than the second fan motor  860 . Reference numeral  859  represents a coupling portion to allow the second fan casing  852  to be fixed to the insulation upper plate  270 . 
     Herein, the bracket mounting portion  852   a , the housing mounting portion  852   b , and the motor mounting portion  852   c  may be provided above a lower end of the second fan casing  852 . Accordingly, both the second fan motor  860  and a second fan blade  865  may be arranged above the lower end of the second fan casing  852 . Both the second fan motor  860  and the second fan blade  865  may be spaced apart from the insulation upper plate  270 . As described above, when the second fan blade  865  is spaced apart from the insulation upper plate  270 , the intake performance of the second fan blade  865  may be improved. 
     A shaft  861  is connected to the second fan motor  860 , and the shaft  861  may be connected to the second fan blade  865 . Herein, the second fan blade  865  may be stored inside the second fan housing  857 , and air may be introduced through an opening of the second fan housing  857 . The second fan blade  865  may discharge air toward a portion, which is open downward, of the second fan housing  857 . In the embodiment, the shaft  861  may be connected only to one second fan blade  865 , but second fan blades  865  may be respectively connected to opposite portions of the shaft  861 . 
     As shown in  FIG.  6   , air is circulated by the second cooling fan module  850 . As shown in the drawing, air discharged downward (direction of arrow {circle around (4)}) from the second cooling fan module  850  may cool the main controller  700  by passing through the main controller  700  arranged in the fourth electric chamber ES 4 . Air flowing further downward may be then introduced into the second electric chamber ES 2 , and flowing forward (direction of arrow {circle around (5)}) to the door  300  to be discharged through the air outlet part  243  of the outer front plate  240 . In this process, the second heat source module  500  may be cooled together. 
     Referring to  FIGS.  4  and  12   , the supply duct  910  may be arranged in the inner casing  100 . The supply duct  910  may be provided to cover the inlet port  123  of the inner casing  100 . The supply duct  910  may provide a path through which air of the electric chamber may be introduced into the cavity S. Air introduced into the cavity S through the supply duct  910  and the inlet port  123  may remove moisture in the cavity S. Herein, air supplied through the inlet port  123  may be a part of air acting heat dissipation (cooling) while passing through the inside space of the casing  100 ,  200 . 
     As shown in  FIG.  12   , the supply duct  910  may be extended in a shape of which a first end is bent. This shape is for the supply duct  910  to avoid interference with the wave guide  420  of the first heat source module  400 . In other words, the supply duct  910  may be arranged at one of the pair of inner side plates  110  of the inner casing  100  with the wave guide  420 , and the supply duct  910  may be arranged at a different height from the wave guide  420 . 
     The first end of the supply duct  910  may cover the inlet port  123 , and a remaining portion of the supply duct  910  may provide a flow path in the cooking appliance while being in close contact with an outer surface of the inner side plate  110 . This supply duct  910  may transfer air discharged from the first cooling fan module  810  to the inlet port  123 , so that air supply into the cavity S may be efficiently performed. 
     A duct assembly  920  may be provided at a second end of the supply duct  910 . The duct assembly  920  may be an opening and closing device to block air inflow. As shown in  FIG.  10   , the duct assembly  920  may be arranged in the third electric chamber ES 3 . Specifically, the duct assembly  920  may be arranged at a lower portion of the first drive housing  817   a  of the first cooling fan module  810 . Therefore, air discharged from the first drive housing  817   a  may be transferred to the duct assembly  920 . 
     The duct assembly  920  may connect or block the supply duct  910  to or from the third electric chamber ES 3 . In other words, the duct assembly  920  may selectively supply air into the cavity S via the supply duct  910 . For this operation, the duct assembly  920  may include a duct motor  930 , and operation of the duct motor  930  may be controlled by the main controller  700 . 
       FIGS.  45  and  46    are views showing the duct assembly  920  according to an embodiment of the present disclosure. For example, the duct assembly  920  may include a duct housing  921 , a duct blade  925  rotatably coupled to the duct housing  921 , and the duct motor  930  rotating the duct blade  925 . The duct housing  921  may include a duct bracket  922   a  that may fix the duct assembly  920  to the casing  100 ,  200  or the insulation rear plate  280 . 
     The duct blade  925  may be assembled to an operation space  923   b  (referring to  FIG.  46   ) of the duct housing  921 . The duct blade  925  may open and close an entrance  923   a  of the duct housing  921  by rotation thereof. The duct blade  925  may open the entrance  923   a  of the duct housing  921  while being rotated in an inward direction of the duct housing  921  (direction of arrow in  FIG.  45   ). Reference numeral  925   a  represents a hinge portion coupled to a shaft of the duct blade  925 . 
     The duct housing  921  may include a duct switch  927 . The duct switch  927  may be mounted to a switch piece  922   c  of the duct housing  921 . The duct switch  927  may be turned into the ON state by being pressed in the process where the duct blade  925  is rotated. When the duct switch  927  is in the ON state, the main controller  700  may detect that the duct blade  925  is completely opened. 
     The duct motor  930  may be arranged at a motor mounting piece  922   b  of the duct housing  921 . The duct motor  930  may supply a rotation force to the duct blade  925 . The duct motor  930  may be arranged on a surface of the duct housing  921 , and a shaft  933  of the duct motor  930  may be connected to the hinge portion  925   a  of the duct blade  925 . Reference numeral  931  represents a fixed piece of the duct motor  930  coupled to the motor mounting piece  922   b.    
     Meanwhile, referring to  FIG.  5   , the exhaust duct  940  may be arranged in the fifth electric chamber ES 5 . The exhaust duct  940  may cover the outlet port  125  of the inner casing  100 . The exhaust duct  940  may be arranged in the fifth electric chamber ES 5 , and may guide movement of air discharged from the outlet port  125 . The exhaust duct  940  may be arranged on a surface of one of the inner side plates  110 . Accordingly, air in the cavity S discharged to the outlet port  125  may move downward. The air moving downward may be guided to the second electric chamber ES 2 , and may be discharged to the air outlet part  243  of the outer front plate  240 . 
     As shown in  FIG.  11   , the exhaust duct  940  may be arranged on one of the inner side plate  110  of the inner casing  100  with the main controller  700 . In other words, the exhaust duct  940  may be arranged on the surface of the inner side plate  110  together with the main controller  700 . Herein, the exhaust duct  940  may be arranged at a position farther from the door  300  than the main controller  700 . Therefore, air in the cavity S may be discharged from a rear portion of the casing  100 ,  200  farther from the door  300 , and in a process in which air is discharged along the second electric chamber ES 2 , air may pass through a lower portion of the second heat source module  500 , so that the second heat source module  500  may be cooled by the air. 
       FIG.  43    is a view showing the structure of the exhaust duct  940  in detail. As shown in the drawing, the exhaust duct  940  may have an approximately vertically long shape. A prevention portion  941  may be provided along an edge of the exhaust duct  940  to prevent leakage of air. A step portion  943  may be provided at one portion of the exhaust duct  940  with a relatively less thickness, and a portion of the main controller  700  may be provided at the step portion  943 . Furthermore, in the embodiment, as described above, the second temperature sensor  760  and the humidity sensing module  750  may be arranged on the exhaust duct  940 . 
     A guide blade  945  may be provided at a lower end of the exhaust duct  940 . The guide blade  945  may be extended in a downward inclined direction unlike the prevention portion  941 . Accordingly, the guide blade  945  may serve as an outlet through which air is discharged. The guide blade  945  may be extended toward the second electric chamber ES 2 , thereby discharging air in the exhaust duct  940  to the second electric chamber ES 2 . 
     As shown in  FIGS.  4  and  6   , an air barrier  950  may be arranged between the outer front plate  240  and the insulation rear plate  280 . The air barrier  950  may prevent or substantially prevent air discharged by the first cooling fan module  810  and the second cooling fan module  850  from being re-suctioned into the first cooling fan module  810  or the second cooling fan module  850 . In other words, the air barrier  950  may prevent air, which is discharged from the first cooling fan module  810  and the second cooling fan module  850  and is introduced into the second electric chamber ES 2  through the third electric chamber ES 3  and the fifth electric chamber ES 5 , from being transferred to the fourth electric chamber ES 4 . 
     As shown in  FIG.  6   , air discharged toward the third electric chamber ES 3  (direction of arrow {circle around (1)}, {circle around (2)}) may be transferred to the second electric chamber ES 2  by the first cooling fan module  810 . Herein, the air barrier  950  arranged at the left side in the drawing may prevent air discharged from the first cooling fan module  810  from passing over the air barrier  950  to the fourth electric chamber ES 4 . Accordingly, air discharged from the first cooling fan module  810  may move forward (direction of arrow {circle around (5)}) to be discharged outward via an air outlet provided in the outer front plate  240 . 
     Furthermore, air discharged downward through the exhaust duct  940  (direction of arrow {circle around (3)}), and air discharged toward the fifth electric chamber ES 5  (direction of arrow {circle around (4)}) by the second cooling fan module  850  may be transferred to the second electric chamber ES 2 . Herein, the air barrier  950  at the left side may prevent the air discharged from the exhaust duct  940  and the second cooling fan module  850  from moving over the air barrier  950  to the fourth electric chamber ES 4 . Accordingly, the air discharged from the exhaust duct  940  and the second cooling fan module  850  may move forward (direction of arrow {circle around (5)}) and may be discharged to the outside space through the air outlet provided in the outer front plate  240 . 
     In order to control the flow of air, the air barrier  950  may be arranged to cross between the outer front plate  240  and the insulation rear plate  280 . Furthermore, the air barrier  950  may connect the outer front plate  240  to the insulation rear plate  280 , and support the lower portion of the casing  100 ,  200  and reinforce the strength of the entire casing  100 ,  200 . 
       FIGS.  5  to  13    are views showing an air circulation structure in the cooking appliance according to an embodiment of the present disclosure. The cooking appliance of the embodiment may include the first heat source module  400 , the second heat source module  500 , and the third heat source module  600 , so that heat generated from the heat sources may need to be efficiently cooled. Hereinbelow, a cooling structure of the heat sources and other parts will be described. 
     First, as parts required to be cooled in the embodiment: (i) in the first electric chamber ES 1 , the lighting fixture  790 , cooling of the distance sensor  710 , the third heat source module  600 , and the third temperature sensor (not shown) may be required; (ii) in the second electric chamber ES 2 , cooling of the second heat source module  500  may be required; (iii) in the third electric chamber ES 3 , cooling of the power supply unit  770  and the camera module  730  may be required and (iv) in the fifth electric chamber ES 5 , the main controller  700 , the humidity sensing module  750 , the second temperature sensor  760 , and the temperature block switch (not shown) may be required. 
     In order to perform the cooling of the parts, the embodiment may include the first cooling fan module  810  and the second cooling fan module  850  described above. The first cooling fan module  810  may cool the second electric chamber ES 2  and the third electric chamber ES 3 , and the second cooling fan module  850  may cool the first electric chamber ES 1 , the second electric chamber ES 2 , and the fifth electric chamber ES 5 . It is understood that the first cooling fan module  810  may also be arranged at the upper portion of the casing  100 ,  200 , thereby cooling a part of the first electric chamber ES 1 . Furthermore, the first cooling fan module  810  may discharge air toward the duct assembly  920  arranged at the third electric chamber ES 3 , so that the first cooling fan module  810  may serve to supply the air into the cavity S. 
     Specifically, as shown in  FIG.  5   , in the embodiment, both the air inlet part  242  through which external air is suctioned and the air outlet part  243  through which air is discharged may be arranged at a front surface of the cooking appliance. The external air may be introduced into an upper portion of the front surface of the cooking appliance and circulate in the cooking appliance and then be discharged through a lower portion of the front surface of the cooking appliance Therefore, in the embodiment, even when the cooking appliance is installed in a built-in manner, efficient air circulation may be performed. 
     Furthermore, as shown in  FIGS.  5  and  6   , the plurality of electric chambers may be provided outside the inner casing  100 , and air may efficiently cool the parts while flowing through the electric chambers. Herein, the air barrier  950  may prevent air introduced into the second electric chamber ES 2  from moving upward through the fourth electric chamber ES 4 , and therefore, the air may cool the second heat source module  500  of the second electric chamber ES 2  and then move forward to flow through the air outlet part  243 . 
     The insulation upper plate  270  and the insulation rear plate  280  may be arranged outside the inner casing  100  and may prevent heat in the cavity S from being directly transferred to the parts. The insulation upper plate  270  and the insulation rear plate  280  may perform the cooling performance of the cooking appliance together with the first cooling fan module  810  and the second cooling fan module  850 . 
     As shown in  FIG.  5   , the first cooling fan module  810  may be arranged at the insulation upper plate  270 , more specifically, at a position closer to the third electric chamber ES 3  and the fourth electric chamber ES 4  (left side in the drawing) based on a center portion of the insulation upper plate  270 . The second cooling fan module  850  may also be arranged at the insulation upper plate  270 , more specifically, at a position closer to the fifth electric chamber ES 5  based on a center portion of the insulation upper plate  270 . 
     As shown in  FIG.  9   , flows of air suctioned by the first cooling fan module  810  and the second cooling fan module  850  are represented. Air suctioned through the outer front plate  240  may be introduced into the first cooling fan module  810 . Herein, the first cooling fan module  810  may include the first drive housing  817   a  and the second drive housing  817   b , so that air may be introduced in two streams. Herein, air introduced along the left side (direction of arrow {circle around (1)}) of the cooking appliance by the first drive housing  817   a  may flow along a gap between the heater housing  632  of the third heat source module  600  and the outer upper plate  230  (which is omitted in  FIG.  9   ) arranged at a left edge of the casing  100 ,  200 . Air introduced along the right side (direction of arrow {circle around (2)}) of the cooking appliance by the second drive housing  817   b  may flow along a gap between the heater housing  632  of the third heat source module  600  and the guide fence GF. In this process, the distance sensor  710 , the lighting fixture  790 , and the third heat source module  600  may be cooled. 
     At the same time, the second cooling fan module  850  may also suction external air through the outer front plate  240 . Air introduced toward the second cooling fan module  850  (direction of arrow {circle around (3)}) may cool the first electric chamber ES 1  while flowing toward the second cooling fan module  850 . 
     The air suctioned by the first cooling fan module  810  and the second cooling fan module  850  may then flow to the lower portion of the cooking appliance. Referring to  FIG.  6   , the air suctioned by the first cooling fan module  810  may be discharged downward, i.e., toward the third electric chamber ES 3  (direction of arrow {circle around (1)}, {circle around (2)}). In this process, the power supply unit  770  may be cooled. Specifically, the high voltage transformer  771  generating high temperature heat may be arranged below the second drive housing  817   b  of the first cooling fan module  810 , so that the high voltage transformer  771  may be efficiently cooled. 
     Air passing through the third electric chamber ES 3  may be introduced into the second electric chamber ES 2  through the ventilation part  283  provided at the lower portion of the insulation rear plate  280 . Air cooling the second heat source module  500  in the second electric chamber ES 2  may be discharged to the outside space (direction of arrow {circle around (5)}) through the air outlet part  243 . 
     Meanwhile, air suctioned by the second cooling fan module  850  may also be discharged downward, i.e., toward the fifth electric chamber ES 5  (direction of arrow {circle around (4)} in  FIG.  6   ). In this process, the main controller  700  and the humidity sensing module  750  arranged at the exhaust duct  940 , and the second temperature sensor  760  may be cooled. Specifically, the main controller  700  generating high temperature heat may be arranged below the second fan blade  865 , so that the main controller  700  may be efficiently cooled. 
     Next, air passing through the fifth electric chamber ES 5  may be introduced into the second electric chamber ES 2 . Air cooling the second heat source module  500  in the second electric chamber ES 2  may flow forward (direction of arrow {circle around (5)}), and as a result, the air may be discharged to the outside space (direction of arrow {circle around (5)}) through the air outlet part  243 . 
     As shown in  FIG.  6   , air may also be transferred toward the second electric chamber ES 2  through the exhaust duct  940 . The exhaust duct  940  may guide air, which is discharged from the cavity S, downward (direction of arrow {circle around (3)}) to transfer the air to the second electric chamber ES 2 . The air discharged from the cavity S may also be discharged to the outside space (direction of arrow {circle around (5)}) through the air outlet part  243 . 
     Referring to  FIG.  13   , a duct flow path  942  may be provided inside the exhaust duct  940 , and air may flow downward (direction of arrow {circle around (1)}) along the duct flow path  942 . Air may then be introduced into the second electric chamber ES 2  through the guide blade  945  provided in a lower portion of the exhaust duct  940 . 
     As shown in  FIG.  10   , the magnetron  410  constituting the first heat source module  400  may be arranged below the first drive housing  817   a  of the first cooling fan module  810 . Therefore, air discharged downward (direction of arrow {circle around (2)}) from the first drive housing  817   a  may cool the magnetron  410  while flowing. As described above, the high voltage transformer  771  arranged below the second drive housing  817   b  may be cooled as air discharged downward (direction of arrow {circle around (1)}) from the first drive housing  817   a  flows. 
     Referring to  FIG.  11   , the second cooling fan module  850  may suction external air (direction of arrow {circle around (1)}). The second cooling fan module  850  may then discharge air downward (direction of arrow {circle around (2)}) to the fifth electric chamber ES 5 . Air cooling the main controller  700  arranged in the fifth electric chamber ES 5  may be introduced into the second electric chamber ES 2  and then flows forward (direction of arrow {circle around (3)}) to be discharged. 
     Air introduced through the first cooling fan module  810  may then be introduced the rear side of the guide fence GF (direction of arrow {circle around (4)}), and the first cooling fan module  810  may discharge air downward (direction of arrow {circle around (5)}) to the third electric chamber ES 3 . Air cooling the power supply unit  770  arranged in the third electric chamber ES 3  may be introduced into the second electric chamber ES 2  and then flow forward (direction of arrow {circle around (3)}) to be discharged. 
     Herein, the air introduced into the second electric chamber ES 2  by the first cooling fan module  810  and the second cooling fan module  850  may flow only forward, and may not be re-introduced into the fourth electric chamber ES 4 . This is because the air barrier  950  may be arranged below the fourth electric chamber ES 4 . As shown in  FIGS.  6  and  11   , the air barrier  950  may guide air forward. 
       FIG.  12    is a view showing the fourth electric chamber ES 4 . As shown in the drawing, the wave guide  420  constituting the first heat source module  400  and the supply duct  910  may be arranged in the fourth electric chamber ES 4 . Air discharged to the lower side of the first drive housing  817   a  (arrow {circle around (1)}) may be introduced into the supply duct  910 . Herein, although not shown in  FIG.  12   , when the duct assembly  920  provided in the supply duct  910  is opened, the air discharged from the first cooling fan module  810  may be introduced into the supply duct  910  through the duct assembly  920 . The air flowing forward (direction of arrow {circle around (3)}) along the supply duct  910  may be introduced into the cavity S through the inlet port  123  (referring to  FIG.  7   ). Arrow {circle around (4)} represents a moving direction of air introduced into the cavity S. In FIG.  12 , arrow {circle around (2)} represents a direction in which air discharged from the first cooling fan module  810  and introduced into the second electric chamber ES 2  flows along the opposite portion of the air barrier  950 . 
     Next, a method for controlling the cooking appliance in the embodiment will be described. First, a cooking level may be input via the display module  350 . The cooking level may be input directly by the user, or may be automatically selected by the main controller  700  on the basis of an image of food filmed by the camera module  730  or the height of the food measured by the distance sensor  710 . 
     When the cooking level is input, in response to the input cooking level, the main controller  700  may select operation modes of the first heat source module  400 , the second heat source module  500 , and the third heat source module  600 , respectively. Herein, the operation modes of the first heat source module  400 , the second heat source module  500 , and the third heat source module  600  may be differently set, and some or all the first heat source module  400 , the second heat source module  500 , and the third heat source module  600  may be operated at the same time. 
     The operation mode of the first heat source module  400  may be set such that a value of multiplying the input cooking level of the first heat source module  400  and a preset reference time is set as a cooking time of the first heat source module  400 . For example, in a case in which the reference time is 3 seconds, when the cooking level of the first heat source module  400  is input as 10, the first heat source module  400  may be operated for 30 seconds (10*3). Herein, an additional time may be added to the operation time of the first heat source module  400 . For example, when 2 seconds are added, the first heat source module  400  may be operated for total 32 seconds. 
     The operation mode of the second heat source module  500  may be configured such that drive power thereof is adjusted in response to the input second heat source module  500 . The main controller  700  may control the drive power of the second heat source module  500  by the inverter control. The second heat source module  500  may be operated by the selected drive power for the preset cooking time. For example, when the preset cooking time is 12 seconds and the input cooking level is 10, the second heat source module  500  may be operated by heating power of 1600W for 12 seconds. 
     Meanwhile, the operation mode of the third heat source module  600  is configured such that a value obtained by multiplying the input cooking level of the third heat source module  600  and the preset reference time may be set as the cooking time of the third heat source module  600 . For example, in a case in which the reference time is 10 seconds, when the cooking level of the third heat source module  600  is input as 10, the third heat source module  600  may be operated for 100 seconds (10*10). Herein, the heating power of the third heat source module  600  may be 1600W, and the operation mode of the third heat source module  600  may be selected by controlling the number of the driven heating units  610 . 
     As described above, in the embodiment, in the case of the first heat source module  400  and the third heat source module  600 , the operation mode may be selected by adjusting the cooking time. In the case of the second heat source module  500 , the operation mode may be selected by adjusting the drive power through the inverter control. 
     Herein, the third heat source module  600  may move toward the bottom surface of the cavity S, the cooking level of the third heat source module  600  may be selected by operating some or all of the plurality of heating units  610  included in the third heat source module  600 , or by adjusting positions of the heating units  610 . 
     Meanwhile, the first heat source module  400  may be operated only when the third heat source module  600  is in the first location farthest from the bottom surface of the cavity S. This operation is because microwaves generated by the magnetron  410  do not interfere with the third heat source module  600 . 
       FIGS.  47  to  52    are views showing a cooking appliance according to another embodiment of the present disclosure. In  FIGS.  47  to  52   , in addition to the first heat source module  400  to the third heat source module  600  described above, a fourth heat source module  1100  may be included in the cooking appliance. The fourth heat source module  1100  may be arranged at a rear surface of the casing  100 ,  200 . A power supply unit  1770  may be arranged on an upper surface of the casing  100 ,  200 , not the rear surface of the casing  100 ,  200 . Hereinbelow, the same reference numerals are given to the same structures as in the previous embodiment, detailed descriptions are omitted, and a structure different from the previous embodiment will be described. 
     As shown in  FIGS.  47  and  48   , the power supply unit  1770  may be arranged on the insulation upper plate  270 . The power supply unit  1770  may include a high voltage transformer  1771 , and the high voltage transformer  1771  may have relatively large volume and generate high temperature heat. Accordingly, it is important to efficiently cool the high voltage transformer  1771 . 
     For reference, in  FIG.  47   , the outer rear plate  220  is shown, but in  FIG.  48   , the outer rear plate  220  is omitted. In  FIG.  47   , the fourth heat source module  1100  may be arranged in the third electric chamber ES 3  provided between the outer rear plate  220  and the insulation rear plate  280 . As shown in  FIG.  48   , the fourth heat source module  1100  may be provided at the insulation rear plate  280  arranged in front of the outer rear plate  220 . The fourth heat source module  1100  may be a convection heater. In other words, the fourth heat source module  1100  may provide heat for convection-heating of food in the cavity S. 
     As described above, in the embodiment, the first heat source module  400 , the second heat source module  500 , the third heat source module  600 , and the fourth heat source module  1100  may be arranged in the electric chambers differently from each other in the casing  100 ,  200 . In other words, the first heat source module  400 , the second heat source module  500 , the third heat source module  600 , and the fourth heat source module  1100  may be arranged at different surfaces of the casing  100 ,  200  from each other. Furthermore, the plurality of heat sources may be composed of different types of heat sources. Accordingly, the plurality of heat sources may provide different types of heating means to the food from different directions. 
     The fourth heat source module  1100  may be a convection heater. The fourth heat source module  1100  may generate convection heat inside the cavity S together with a convection fan, thereby improving the uniformity of the food. Otherwise, the convection fan is omitted in the fourth heat source module  1100 , and like the third heat source module  600 , the fourth heat source module  1100  may provide the radiant heat to food by using a heating wire. 
     As shown in  FIG.  48   , the fourth heat source module  1100  include the convection housing  1110 . The convection housing  1110  may be arranged at the insulation rear plate  280 , a convection chamber may be provided inside the convection housing  1110 , and a convection heater (not shown) may be arranged in the convection chamber. The convection heater may have a bar type having a predetermined length and a predetermined diameter. For example, the convection heater may be a sheath heater with a metal protection tube of the heating wire. Otherwise, the convection heater may be a carbon heater, a ceramic heater, and a halogen heater in which a filament is sealed inside a tube made of a transparent or translucent material. 
     A motor bracket  1130  may be arranged in the convection housing  1110 , and a convection motor  1120  may be mounted to the motor bracket  1130 . The convection motor  1120  may rotate the convection fan (not shown) in the convection housing  1110 . When the convection fan is rotated by the convection motor  1120 , heat of the convection heater may heat food while performing convection inside the cavity S. Reference numeral  1150  represents an outlet through which heat in the convection chamber is discharged to the outside space. 
     When operation of the fourth heat source module  1100  is input, power may be applied to the convection motor  1120  to rotate the convection fan, and power is applied to the convection heater to heat the convection heater. Therefore, the convection fan generates forced convection between the cavity S and the convection chamber in the convection housing  1110 , and the forced convection by the convection fan becomes hot air by receiving heat from the convection heater, so that the temperature in the cavity S may be increased and food may be heated. 
     Although not shown in the drawings, the inner rear plate  120  of the inner casing  100  may have a convection supply portion that is open to allow heat of the convection heater to be discharged into the cavity S. Furthermore, the inner rear plate  120  may have a separate convection outlet (not shown) distinguish from the convection supply portion. Heat of the convection heater may be discharged through the convection supply portion and circulate in the cavity S, and then the heat may be discharged into the convection chamber again through the convection outlet. 
     Meanwhile, in the embodiment, the power supply unit  1770  may be arranged in the second electric chamber ES 2 , i.e., the upper side of the casing  100 ,  200 . Specifically, the power supply unit  1770  may be arranged at the insulation upper plate  270 . Since the fourth heat source module  1100  may be arranged at the third electric chamber ES 3 , the power supply unit  1770  may be arranged in the second electric chamber ES 2  so as to avoid to be heated by the fourth heat source module  1100 . As shown in  FIGS.  48  and  49   , the power supply unit  1770  may include the high voltage transformer  1771 , the high voltage capacitor  773 , and a fuse  1775 . 
     Herein, the power supply unit  1770  may be arranged between a first cooling fan module  1810  and a second cooling fan module  1850 . As shown in  FIG.  49   , the first cooling fan module  1810  may be arranged at the left side of the power supply unit  1770 , and the second cooling fan module  1850  may be arranged at the right lower side of the power supply unit  1770 . Accordingly, a portion of external air suctioned by the first cooling fan module  1810  may flow toward the first cooling fan module  1810  (direction of arrow {circle around (1)}) between the heater housing of the third heat source module  600  and a left end of the casing  100 ,  200 , and another portion of the external air may flow toward the rear portion of the casing  100 ,  200  (direction of arrow {circle around (2)}) along a gap between the heater housing of the third heat source module  600  and the guide fence GF. 
     Since the power supply unit  1770  is arranged on the path through which air is suctioned toward the first cooling fan module  1810 , the external air suctioned by the first cooling fan module  1810  may pass through the power supply unit  1770  (direction of arrow {circle around (3)}). Therefore, the power supply unit  1770  may be cooled. 
     Since the power supply unit  1770  is arranged above the insulation upper plate  270 , high temperature heat in the cavity S may not be transferred to the power supply unit  1770  through the inner upper plate  160 . Furthermore, (i) the power supply unit  1770  may be arranged at a different surface from the magnetron  410  of the first heat source module  400  arranged in the third electric chamber ES 3  to be spaced apart from each other, (ii) the power supply unit  1770  may be spaced apart from the second heat source module  500  arranged at the bottom of the casing  100 ,  200 , (iii) a gap between the power supply unit  1770  and the heating unit  610  of the third heat source module  600  is partitioned by the heater housing  632 , and (iv) the power supply unit  1770  may be spaced apart from the fourth heat source module  1100  arranged in the third electric chamber ES 3 . Therefore, the power supply unit  1770  may be prevented from being heated by the heat source. Specifically, the main controller  700 , which is another heating element, may be arranged in the fifth electric chamber ES 5 , so that heat generated from the main controller  700  does not affect directly to the power supply unit  1770 . 
     In the embodiment, the first cooling fan module  1810  and the second cooling fan module  1850  may be included for cooling. Both the first cooling fan module  1810  and the second cooling fan module  1850  may be provided to cool the cooking appliance Among the cooling fan modules, the first cooling fan module  1810  may serve to introduce air into the cavity S. 
       FIG.  47    is a view showing the first cooling fan module  1810 . The first cooling fan module  1810  may be arranged on the insulation upper plate  270 . The first cooling fan module  1810  may include a first fan housing  1817 . A first fan motor  1820  may be provided at one portion of the first fan housing  1817 . The first fan motor  1820  may be connected to a shaft (not shown), and the shaft may be coupled to a first fan blade  1825 . 
     The first fan blade  1825  may discharge air downward, i.e., a direction of gravity. As shown in  FIG.  50   , air is discharged downward from the first cooling fan module  1810 . The discharged air may be discharged into the third electric chamber ES 3 . The fourth heat source module  1100  and the magnetron  410  of the first heat source module  400  are arranged in the third electric chamber ES 3 , so that the fourth heat source module  1100  and the magnetron  410  may be cooled by the first cooling fan module  1810 . 
     Furthermore, air discharged from the first cooling fan module  1810  may pass through the third electric chamber ES 3 , and may flow downward to be introduced into the second electric chamber ES 2 . As shown in  FIGS.  50  and  51   , a part of the air discharged from the first cooling fan module  1810  may move forward to the door  300  (direction of arrow {circle around (3)} in  FIG.  51   ) along the supply duct  910 , and may be guided toward the inside space of the cavity S (arrow {circle around (4)}). 
     As shown in  FIG.  47   , the second cooling fan module  1850  is shown in the view. The second cooling fan module  1850  may cool the cooking appliance like the first cooling fan module  1810 , and may allow external air to be efficiently supplied into the cavity S. When showing a structure of the second cooling fan module  1850 , the second cooling fan module  1850  may include a second fan housing  1857   a ,  1857   b  forming a frame and a second fan motor  1860  arranged at one portion of the second fan housing  1857   a ,  1857   b.    
     The second fan housing  1857   a ,  1857   b  may include a first drive housing  1857   a  and a second drive housing  1857   b  respectively arranged at opposite sides. The second fan motor  1860  may be arranged between the first drive housing  1857   a  and the second drive housing  1857   b . The second fan motor  1860  may be connected to a shaft (not shown), and the shaft may be coupled to a pair of second fan blades  1865   a  and  1865   b . The shaft may be extended in opposite directions from the second fan motor  1860 , and the pair of second fan blades  1865   a  and  1865   b  may be respectively coupled to opposite portions of the shaft. 
     Herein, the pair of second fan blades  1865   a  and  1865   b  may be respectively arranged in the first drive housing  1857   a  and the second drive housing  1857   b . One  1865   a  of the pair of second fan blades  1865   a  and  1865   b  may discharge air in the direction of gravity, and the rest  1865   b  may discharge air in a direction perpendicular to the direction of gravity, i.e., a direction of the first electric chamber ES 1 . As shown in  FIG.  52   , the first drive housing  1857   a  may be open downward, so that the second fan blade  1865   a  provided in the first drive housing  1857   a  may discharge air downward (direction of arrow {circle around (2)}). Accordingly, the main controller  700  arranged in the fifth electric chamber ES 5  may be cooled. 
     Meanwhile, referring to  FIG.  48   , an outlet  1857   b ′ of the second drive housing  1857   b  may be open toward the first electric chamber ES 1 . Accordingly, the second fan blade  1865   b  arranged in the second drive housing  1857   b  may discharge air toward the first electric chamber ES 1 , more specifically, toward the power supply unit  1770  through the outlet  1857   b ′ of the second drive housing  1857   b . Accordingly, the second cooling fan module  1850  may cool the power supply unit  1770 . 
     The air cooling the power supply unit  1770  may flow downward. As shown in  FIG.  52   , air is introduced into an inward direction (arrow {circle around (4)}) of the second drive housing  1857   b , and then may flow toward the third electric chamber ES 3  (arrow {circle around (6)}) by passing through the power supply unit  1770 . In this process, the fourth heat source module  1100  may be cooled. 
       FIGS.  49  to  52    are views showing an air circulation structure in the cooking appliance according to an embodiment of the present disclosure. The cooking appliance may include the first heat source module  400 , the second heat source module  500 , the third heat source module  600 , and the fourth heat source module  1100 , so that heat generated from the heat sources needs to be cooled. Hereinbelow, a cooling structure of the heat sources and other parts will be described. 
     First, as parts required to be cooled in the embodiment: (i) in the first electric chamber ES 1 , the lighting fixture  790 , cooling of the distance sensor  710 , the third heat source module  600 , the third temperature sensor (not shown), and the power supply unit  1770  may be required; (ii) in the second electric chamber ES 2 , cooling of the second heat source module  500  may be required; (iii) in the third electric chamber ES 3 , cooling of the fourth heat source module  1100  and the camera module  730  may be required; and (iv) in the fifth electric chamber ES 5 , the main controller  700 , the humidity sensing module  750 , the second temperature sensor  760 , and the temperature block switch (not shown) may be required. 
     In order to perform the cooling of the parts, the embodiment may include the first cooling fan module  1810  and the second cooling fan module  1850  described above. The first cooling fan module  1810  may cool the second electric chamber ES 2  and the third electric chamber ES 3 , and the second cooling fan module  1850  may cool the first electric chamber ES 1 , the second electric chamber ES 2 , and the fifth electric chamber ES 5 . Of course, the first cooling fan module  1810  may also be arranged at the upper portion of the casing  100 ,  200 , thereby cooling a part of the first electric chamber ES 1 . Furthermore, the first cooling fan module  1810  may discharge air toward the duct assembly  920  arranged in the third electric chamber ES 3 , so that the first cooling fan module  1810  may serve to supply the air into the cavity S. 
     Specifically, as shown in  FIG.  47   , both the air inlet part  242  through which external air is suctioned and the air outlet part  243  through which air is discharged may be arranged at a front surface of the cooking appliance. The external air may be introduced into an upper portion of the front surface of the cooking appliance and circulate in the cooking appliance and then be discharged through a lower portion of the front surface of the cooking appliance. Accordingly, even when the cooking appliance is installed in a built-in manner, efficient air circulation may be performed. 
     Furthermore, as shown in  FIGS.  47  and  48   , the plurality of electric chambers may be provided outside the inner casing  100 , and air may efficiently cool the parts while flowing through the electric chambers. Herein, the air barrier  950  may prevent air introduced into the second electric chamber ES 2  from moving upward through the fourth electric chamber ES 4 , and therefore, the air may cool the second heat source module  500  of the second electric chamber ES 2  and then move forward to flow through the air outlet part  243 . 
     The insulation upper plate  270  and the insulation rear plate  280  may be arranged outside the inner casing  100  and may prevent heat in the cavity S from being directly transferred to the parts. The insulation upper plate  270  and the insulation rear plate  280  may perform the cooling performance of the cooking appliance together with the first cooling fan module  1810  and the second cooling fan module  1850 . 
     As shown in  FIG.  47   , the first cooling fan module  1810  may be arranged at the insulation upper plate  270 , more specifically, at a position closer to the third electric chamber ES 3  and the fourth electric chamber ES 4  (left side in the drawing) based on a center portion of the insulation upper plate  270 . The second cooling fan module  1850  may also be arranged at the insulation upper plate  270 , more specifically, at a position closer to the fifth electric chamber ES 5  based on a center portion of the insulation upper plate  270 . 
     As shown in  FIG.  49   , the view shows flows of air suctioned by the first cooling fan module  1810  and the second cooling fan module  1850 . Air suctioned through the outer front plate  240  may be introduced into the first cooling fan module  1810 . Herein, the air may be introduced toward the first cooling fan module  1810  in two streams. Herein, air introduced along the left side (direction of arrow {circle around (1)}) of the cooking appliance by the first cooling fan module  1810  may flow along a gap between the heater housing  632  of the third heat source module  600  and the outer upper plate  230  (which is omitted in  FIG.  49   ) arranged at a left edge of the casing  100 ,  200 . Air introduced along the right side (direction of arrow {circle around (2)}) of the cooking appliance by the first cooling fan module  1810  may flow along a gap between the heater housing  632  of the third heat source module  600  and the guide fence GF. 
     As described above, in the process in which air is suctioned into the first cooling fan module  1810 , the distance sensor  710 , the lighting fixture  790 , and the third heat source module  600  may be cooled. Furthermore, the power supply unit  1770  arranged on the flow path of air may be cooled. Arrow {circle around (3)} represents a direction in which air suctioned into the first cooling fan module  1810  pass through the power supply unit  1770 . Therefore, the power supply unit  1770  may be cooled by the first cooling fan module  1810 . 
     At the same time, the second cooling fan module  1850  may also suction external air through the outer front plate  240 . Air introduced toward the second cooling fan module  1850  (direction of arrow {circle around (4)}) may cool the first electric chamber ES 1  while flowing toward the second cooling fan module  1850 . Herein, two streams of air may be suctioned toward the first drive housing  1857   a  and the second drive housing  1857   b  included in the second cooling fan module  1850 . Air suctioned toward the first drive housing  1857   a  may be introduced through the air inlet part  242  of the outer front plate  240 , and may cool a front portion of the first electric chamber ES 1  closer to the door  300 . 
     The air suctioned by the first cooling fan module  1810  and the second cooling fan module  1850  may flow to the lower portion of the cooking appliance Referring to  FIG.  5   , the air suctioned by the first cooling fan module  1810  may be discharged downward, i.e., toward the third electric chamber ES 3  (direction of arrow {circle around (1)}). In this process, the magnetron  410  of the first heat source module  400  may be cooled. The magnetron  410  constituting the first heat source module  400  is arranged at a lower portion of the first cooling fan module  1810 , so that air discharged downward (direction of arrow {circle around (1)}) from the first cooling fan module  1810  may cool the magnetron  410  while flowing. Air passing through the third electric chamber ES 3  may then be introduced into the second electric chamber ES 2  through the ventilation part  283  provided at the lower portion of the insulation rear plate  280 . 
     Meanwhile, as shown in  FIG.  52   , air suctioned into the first drive housing  1857   a  of the second cooling fan module  1850  may be discharged downward, i.e., toward the fifth electric chamber ES 5  (direction of arrow {circle around (4)}). In this process, the main controller  700  and the humidity sensing module  750  arranged at the exhaust duct  940 , and the second temperature sensor  760  may be cooled. Specifically, the main controller  700  generating high temperature heat may be arranged below the first drive housing  1857   a , so that the main controller  700  may be efficiently cooled. 
     Next, air passing through the fifth electric chamber ES 5  may be introduced into the second electric chamber ES 2 , air cooling the second heat source module  500  in the second electric chamber ES 2  may be discharged to the outside space (direction of arrow {circle around (3)}) through the air outlet part  243 . 
     Meanwhile, air suctioned into the second drive housing  1857   b  of the second cooling fan module  1850  may be discharged in a horizontal direction, not the direction of gravity. Specifically, as shown in  FIG.  50   , air suctioned into the second drive housing  1857   b  may be discharged toward the first electric chamber ES 1 , i.e., the power supply unit  1770  through an outlet  1857   b ′ of the second drive housing  1857   b  (referring to  FIG.  48   ). Accordingly, the second cooling fan module  1850  may cool the power supply unit  1770 . 
     The air cooling the power supply unit  1770  may flow downward. As shown in  FIG.  50   , air discharged from the second drive housing  1857   b  may be discharged toward the power supply unit  1770  and then flow downward to the third electric chamber ES 3  (arrow {circle around (2)}). In this process, the fourth heat source module  1100  may be cooled. Air passing through the fourth heat source module  1100  may be finally introduced into the second electric chamber ES 2  and then flow forward to be discharged through the air outlet part  243 . 
     As shown in  FIG.  52   , air may also be transferred toward the second electric chamber ES 2  through the exhaust duct  940 . The exhaust duct  940  may guide air, which is discharged from the cavity S, downward (direction of arrow {circle around (5)}) to transfer the air to the second electric chamber ES 2 . The air discharged from the cavity S may also be discharged to the outside space (direction of arrow {circle around (3)}) through the air outlet part  243 . 
     Herein, the air introduced into the second electric chamber ES 2  by the first cooling fan module  1810  and the second cooling fan module  1850  may flow only forward, and may not be re-introduced into the fourth electric chamber ES 4 . This is because the air barrier  950  may be arranged below the fourth electric chamber ES 4 . As shown in  FIG.  52   , the air barrier  950  may guide air forward. 
       FIG.  51    is a view showing the fourth electric chamber ES 4 . As shown, the wave guide  420  constituting the first heat source module  400  and the supply duct  910  may be arranged in the fourth electric chamber ES 4 . Air discharged to the lower side of the first cooling fan module  1810  (arrow {circle around (1)}) may be introduced into the supply duct  910 . Herein, although not shown in  FIG.  51   , when the duct assembly  920  provided in the supply duct  910  is opened, the air discharged from the first cooling fan module  1810  may be introduced into the supply duct  910  through the duct assembly  920 . The air flowing forward (direction of arrow {circle around (3)}) along the supply duct  910  may be introduced into the cavity S through the inlet port  123  (referring to  FIG.  47   ). Arrow {circle around (4)} represents a moving direction of air introduced into the cavity S. In  FIG.  51   , arrow {circle around (2)} represents a direction in which air discharged from the first cooling fan module  1810  and introduced into the second electric chamber ES 2  flows along the opposite portion of the air barrier  950 . 
     Through the flow of air as described above, the first heat source module  400  to the fourth heat source module  1100 , the power supply unit  1770 , the magnetron  410 , the main controller  700 , etc. may be cooled. Furthermore, the flow paths of the embodiment may prevent air from flowing backward, and may guide air in a constant direction to perform efficient cooling. Specifically, in the embodiment, even when a separate tubular structure is not provided, a flow of air may be generated by using a gap between the parts. 
     Embodiments of the present disclosure are described with reference to the accompanying drawings. The disclosure may, however, be embodied in many different manners and should not be construed as limited to the embodiments set forth herein. It is understood that a person having ordinary skill in the art to which the present disclosure art would implement this disclosure in other specific manners without changing the technical idea or necessary features of the present disclosure. For this reason, the disclosed embodiments are intended to be illustrative in all aspects, and not restrictive.