Abstract:
A display device is provided. The display device includes a transparent display panel; and an optical switching element arranged on the transparent display panel and configured to be switched into any of transmissive state, non-transmissive state, and reflective state, wherein the optical switching element includes a non-transmission layer formed to contact the transparent display panel and switched into transmissive state or non-transmissive state, and a reflection layer formed on one side of the non-transmission layer and switched into transmissive state or reflective state.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority benefit from Korean Patent Application No. 10-2014-0098898, filed on Aug. 1, 2014 in the Korean Intellectual Property Office and Korean Patent Application No. 10-2014-0116071 filed on Sep. 2, 2014 in the Korean Intellectual Property Office, the entire disclosures of which are incorporated by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present disclosure relates to an oven with an improved cooling structure of the door to open/close a cooking room. 
         [0004]    2. Description of the Related Art 
         [0005]    Ovens are cooking appliances used for cooking a substance by sealing up and heating the substance, and may be generally classified by their heat-source into electric, gas, and microwave ovens. Electric ovens use electric heaters as heat sources, and gas and microwave ovens use heat from gas and frictional heat of water molecules at high frequencies as heat sources, respectively. 
         [0006]    The oven includes a cooking room for cooking, and a machine room for containing electrical and mechanical components. In the process of cooking, the cooking room is shut tight to prevent the internal high temperature heat from seeping out. Inside the tightly shut cooking room, foreign materials like grease are made during a process of cooking, and some of the foreign materials are stuck to the inside wall of the cooking room. 
         [0007]    Ovens equipped with various cleaning systems have been developed to remove the foreign materials remaining inside the cooking room. One of the various cleaning systems uses a method for removing the foreign materials stuck to the inside wall of the cooking room and the inner side of the front door by using high temperatures inside the cooking room. This type of oven generates heat of 400˜500° C. inside the cooking room to remove the foreign materials stuck to the inside wall of the shut cooking room and the inner side of the front door. 
         [0008]    The oven has a structure capable of insulation and cooling to prevent high temperatures inside the cooking room from being delivered to outer sides of the oven. The door of the oven in particular serves to drop the temperature of the outer side of the door by enabling circulation of outdoor air into the inner space. The outdoor air flowing into the inner space of the door, however, affects not only the temperature of the outer side of the door but also the temperature of the inner side. 
       SUMMARY 
       [0009]    In an aspect of one or more embodiments, the present disclosure provides an oven and its door assembly with an improved structure to efficiently clean the inner wall of the cooking room and the inner side of the door by using high temperatures inside the cooking room. 
         [0010]    In an aspect of one or more embodiments, the present disclosure provides an oven and its door assembly with an improved structure to cool off the outer side of the door while keeping the inner side of the door at the same temperature of the inner wall of the cooking room. 
         [0011]    The present disclosure also provides an oven and method for controlling the same, by which information regarding operation of a heat source is visualized on the outer side of the oven. 
         [0012]    In accordance with an aspect of the present disclosure, an oven is provided. The oven includes a casing; a cooking room located inside the casing and having an open front; and a door assembly mounted to the cooking room to open and close the open front of the cooking room, wherein the door assembly has an inner space and the door assembly includes a rear plate and a front plate to form the inner space of the door assembly, a first inner plate installed in the inner space to divide the inner space; and a shielding member located between the first inner plate and the rear plate of the door assembly to block air circulation between the first inner plate and the rear plate. 
         [0013]    The first inner plate may be arranged in a position to face the rear plate of the door assembly, and a distance between the first inner plate and the rear plate of the door assembly may be narrower than a distance between the first inner plate and the front plate of the door assembly. 
         [0014]    The door assembly may further include a second inner plate located between the first inner plate and the front plate of the door assembly to divide a space between the first inner plate and the front plate of the door assembly, wherein a distance between the first inner plate and the second inner plate may be wider than a distance between the first inner plate and the rear plate of the door assembly. 
         [0015]    The distance between the first inner plate and the rear plate of the door assembly may be narrower than a distance between the second inner plate and the front plate of the door assembly. 
         [0016]    The front plate, the rear plate, the first inner plate and the second inner plate of the door assembly may each have at least a part formed of a glass of a transparent material. 
         [0017]    The shielding member may be arranged to extend along a bottom of the first inner plate to block outdoor air from flowing between the first inner plate and the rear plate of the door assembly. 
         [0018]    The shielding member may be arranged in a form of surrounding edges of a space formed between the first inner plate and the rear plate of the door assembly. 
         [0019]    The shielding member may extend along both sides of the first inner plate and the bottom of the inner plate. 
         [0020]    The door assembly may have an open bottom and a flow-out hole arranged on one side of a top of the door assembly. 
         [0021]    The oven may further include a cooling fan unit including a cooling fan located between the casing and a top of the cooking room; and a cooling fan fluid path that runs from the cooling fan to a front of the oven, wherein the flow-out hole may be arranged in a position to face the cooling fan fluid path. 
         [0022]    In accordance with aspect of the present disclosure, an oven having a heat cleaning mode for cleaning an inner wall of a cooking room and an inner side of a door assembly facing the cooking room by using high temperatures is provided. The oven may include a casing; a cooking room located inside the casing and having an open front; and a door assembly having at least one fluid path formed therein and the door assembly mounted to the cooking room to open and close the open front of the cooking room, wherein the door assembly may include a rear plate, a first fluid path formed along the rear plate of the door assembly to provide a space; and a shielding member installed inside the first fluid path for blocking air circulation in the first fluid path. The oven may further include a second fluid path which is formed separately from the first fluid path and which provides a space for air circulation. The first fluid path may be separated from the second fluid path by a first inner plate. 
         [0023]    The first fluid path may have a first width which is narrower than a second width of the second fluid path. 
         [0024]    The shielding member may be located on a lower side of the first fluid path for shielding the first fluid path. 
         [0025]    The shielding member may have a rectangular shape to shield the top, bottom, and both sides of the first fluid path. 
         [0026]    The door assembly may further include a front plate and a third fluid path which is formed along the front plate of the door assembly and which is formed separately from the second fluid path in order to provide a space for air circulation from the bottom toward the top, wherein the third fluid path may have a third width which is wider than the first width of the first fluid path. 
         [0027]    The door assembly may further include a second inner plate positioned between the first inner plate and the front plate for forming the second and third fluid paths. The first inner plate may form the first fluid path with the rear plate of the door assembly. The first inner plate may form the second fluid path with the second inner plate, and the second inner plate may form the third fluid path with the front plate. 
         [0028]    The front plate, the rear plate, the first inner plate and the second inner plate of the door assembly may each have at least a part formed of a glass of a transparent material. 
         [0029]    The door assembly may enable air flowing into an inside of the door assembly through a bottom flow-in unit to move outside of the door assembly through a flow-out hole formed on one side of a top of the door assembly. 
         [0030]    The oven may further include a cooling fan unit including a cooling fan located between the casing and a top of the cooking room; and a cooling fan fluid path that runs from the cooling fan to a front of the oven, wherein the flow-out hole may be arranged in a position to face the cooling fan fluid path. 
         [0031]    In accordance with an aspect of the present disclosure, a door assembly having an inner space and serving to open and close a cooking room of an oven is provided. The door assembly may include a first inner plate positioned in the inner space to face a rear plate of the door assembly and to divide the inner space; and a shielding member located between the first inner plate and the rear plate of the door assembly to block air circulation. 
         [0032]    A distance between the first inner plate and the rear plate of the door assembly may be narrower than a distance between the first inner plate and a front plate of the door assembly. 
         [0033]    The door assembly may further include a second inner plate located between the first inner plate and the front plate of the door assembly to divide a space between the first inner plate and the front plate of the door assembly, wherein a distance between the first inner plate and the second inner plate may be wider than a distance between the first inner plate and the rear plate of the door assembly. 
         [0034]    The shielding member may be positioned to extend along the bottom of the first inner plate to block outdoor air from flowing between the first inner plate and the rear plate of the door assembly. 
         [0035]    The shielding member may be arranged in a form of surrounding edges of a space formed between the first inner plate and the rear plate of the door assembly. 
         [0036]    A distance between the second inner plate and the front plate of the door assembly may be wider than the distance between the first inner plate and the rear plate of the door assembly. 
         [0037]    A distance between the first inner plate and a second inner plate may be wider than the distance between the second inner plate and the front plate of the door assembly. 
         [0038]    In an aspect of the present disclosure, an oven is provided. The oven includes a casing; a cooking room located inside the casing; and a display located on the outside of the casing for displaying an operation of a heat source as a predetermined graphic image or displaying temperatures of the cooking room as colors of the graphic image. 
         [0039]    The display may display thermal diffusion in the cooking room due to operation of the heat source as graphic images. 
         [0040]    The display may display an operation of the heat source at least one of a cooking mode and a cleaning mode as a predetermined graphic image. 
         [0041]    The heat source may include multiple heat sources, and the graphic image may include multiple graphic images that correspond to the multiple heat sources. 
         [0042]    The heat source may include at least one of a convection fan installed in the back of the cooking room, and a heating source installed on the top or bottom of the cooking room. 
         [0043]    The display may display a change in temperature in the cooking room due to operation of the heat source as a change in color of the graphic image. 
         [0044]    The display may be installed in front of the cavity. 
         [0045]    In an aspect of the present disclosure, a method for controlling the oven is provided. The method includes displaying an operation of a heat source as a predetermined graphic image, and displaying temperatures of a cooking room as colors of the graphic image. 
         [0046]    Displaying an operation of a heat source as a predetermined graphic image may include displaying thermal diffusion in the cooking room due to operation of the heat source as graphic images. 
         [0047]    Displaying an operation of a heat source as a predetermined graphic image may include displaying an operation of the heat source in at least one of a cooking mode and a cleaning mode as a predetermined graphic image. 
         [0048]    The heat source may include multiple heat sources, and the graphic image may include multiple graphic images that correspond to the multiple heat sources. 
         [0049]    Displaying temperatures of a cooking room as colors of the graphic image may include displaying a change in temperature in the cooking room as a change in color of the graphic image. 
         [0050]    Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0051]    The above and other features and advantages of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0052]      FIG. 1  is a front view of an oven, according to an embodiment of the present disclosure; 
           [0053]      FIG. 2  is a side cross-sectional view of an oven, according to an embodiment of the present disclosure; 
           [0054]      FIG. 3  is a perspective view of a rear side of a door assembly, according to an embodiment of the present disclosure; 
           [0055]      FIG. 4  is an exploded view of a structure of a door assembly, according to an embodiment of the present disclosure; 
           [0056]      FIG. 5  is a side cross-sectional view of a door assembly, according to an embodiment of the present disclosure; 
           [0057]      FIG. 6  shows a shielding member combined on the inner side of a door assembly, according to an embodiment of the present disclosure; 
           [0058]      FIG. 7  shows a modified example of the shielding member of  FIG. 6 ; and 
           [0059]      FIG. 8  shows a modified example of the shielding member of  FIG. 6 . 
           [0060]      FIG. 9  is a front view of an oven, according to an embodiment of the present disclosure; 
           [0061]      FIG. 10  is a side cross-sectional view of an oven, according to an embodiment of the present disclosure; 
           [0062]      FIG. 11  is a control block diagram of an oven, according to an embodiment of the present disclosure; 
           [0063]      FIGS. 12 to 15  illustrate operation of a heat source and thermal diffusion in cooking mode visualized on a display; 
           [0064]      FIG. 16  illustrates operation of a heat source and the rising of temperature in the oven room, visualized on a display; and 
           [0065]      FIG. 17  is a flowchart illustrating a method for controlling an oven, according to an embodiment of the present disclosure. 
       
    
    
       [0066]    Throughout the drawings, like reference numerals will be understood to refer to like parts, components, and structures. 
       DETAILED DESCRIPTION 
       [0067]    Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. 
         [0068]      FIG. 1  is a front view of an oven, according to an embodiment of the present disclosure, and  FIG. 2  is a side cross-sectional view of an oven, according to an embodiment of the present disclosure. 
         [0069]    As shown in  FIGS. 1 and 2 , an oven  1  may include a casing  10  that forms the exterior shape, and a cooking room  30  located inside the casing  10 . 
         [0070]    The casing  10  may include a side casing  10   b  (of  FIG. 3 ) formed on both sides of the oven  1 , a rear casing  10   c  formed in the back, a top casing  10   a  formed on the top, and a bottom casing  10   d  combined to the bottom floor. A hole (not shown) may be formed in at least a part of the casing  10  to make outdoor air flow into the casing  10 . 
         [0071]    The cooking room  30  may have the form of a box comprised of a cooking room top plate  30   a  forming the top, two cooking room side plates (not shown) forming the both sides, a cooking room back plate ( 30   c ) forming the back, and a cooking room bottom plate  30   d  forming the bottom. The cooking room  30  may be formed to have an open front for putting in or taking out a cooking substance. 
         [0072]    A machine room  31  containing various mechanical and electrical parts such as circuit boards (not shown) is arranged on top of the cooking room  30 . A control panel  15  for controlling the machine room  31  may include a display  13  for displaying various operation information of the oven  1 , and a controlling unit  14  for controlling operation of the oven  1 . 
         [0073]    In addition, a rack (not shown) to place a cooking substance thereon may be equipped inside the cooking room  30 , and a plurality of supporters (not shown) may be arranged to install the rack. The supporters may be arranged to protrude from left and right side walls of the cooking room  30 . 
         [0074]    At least one circulation fan unit  60  may be combined onto the cooking room back plate  30   c  of the cooking room  30 . In an embodiment of the present disclosure, two circulation fan units  60  are combined onto the cooking room back plate  30   c  of the cooking room  30 . Each circulation fan unit  60  may include a circulation motor  61  and a circulation fan  63 . A circulation fan cover  62  formed of flat-typed members may cover the circulation fan  63 . One or more through holes (not shown) may be formed on the circulation fan cover  62 . With the through holes, a fluid that passed by the circulation fan  63  may move into the cooking room  30  through the through holes. 
         [0075]    A cooling fan unit  50  may be installed in the machine room  31  to cool off the inside of the machine room  31 . The cooling fan unit  50  may suck outdoor air into the machine room  31  and then discharge the air forward of the oven  1 . 
         [0076]    The cooling fan unit  50  may include a cooling fan  51 , and a cooling fan housing  58  combined onto the top of the top panel  20   a.  The cooling fan  51  may be combined on a side of the cooling fan housing  58 , and move the air inside the machine room  31  to the inside of the cooling fan housing  58 . A cooling fan fluid path  59  may be arranged inside the cooling fan housing  58 . The cooling fan fluid path  59  may be formed to run from the cooling fan  51  to the front face of the oven  1 . The cooling fan fluid path  59  may be formed to have an open front to discharge the air inside the cooling fan housing  58 . 
         [0077]    The cooking room  30  and the cooling fan unit  50  may be connected to each other via a separate fluid path (not shown). During the process of cooking, at least a part of a fluid of the cooking room  30  may flow into the cooling fan unit  60  through the fluid path and then be discharged forward of the oven  1 . 
         [0078]    A panel  20  may be situated between the casing  10  and the cooking room  30 . The panel  20  may be positioned to be spaced apart from the casing  10 . This may enable a fluid path for air flow to be formed between the casing  10  and the panel  20 . 
         [0079]    The panel  20  may be comprised of a back panel  20   c  arranged to face the cooking room back plate  30   c,  side panels (not shown) arranged to face the cooking room side plates (not shown), and a top panel  20   a  arranged to face the cooking room top plate  30   a.  At least one slit (not shown) may be formed on at least a part of the panel  20 , which enables the air to be moved over the outer surface of the panel  20 . 
         [0080]    Insulation  39  may be arranged between the cooking room  30  and the panel  20 . Specifically, the insulation  39  may be filled between the cooking room top plate  30   a  and the top panel  20   a,  the cooking room back plate  30   c  and the back panel  20   c,  the cooking room side plates and the side panels (not shown), and the cooking room bottom plate  30   d  and a bottom panel  20   d.  The insulation  39  may prevent heat inside the cooking room  30  from being delivered to the machine room  31  and to the outside of the oven  1 . 
         [0081]    The open front of the cooking room  30  may be open or closed by a door assembly  100 . The door assembly  100  may be hinged to the cooking room  30  to be able to rotate upward or downward. 
         [0082]    The oven  1  in accordance with an embodiment of the present disclosure may include a heat cleaning mode for cleaning the inner wall of the cooking room  30  and the inner side of the door assembly  100  facing the cooking room  30  by using high temperatures inside the cooking room  30 . The door assembly  100  having an improved structure to improve the efficiency of the heat cleaning mode will now be described in detail in accordance with embodiments of the present disclosure. 
         [0083]      FIG. 3  is a perspective view of a rear side of a door assembly, according to an embodiment of the present disclosure, and  FIG. 4  is an exploded view of a structure of a door assembly, according to an embodiment of the present disclosure. 
         [0084]    Referring to  FIGS. 2 to 4 , the door assembly  100  in accordance with an embodiment of the present disclosure may include a front plate  101 , a rear plate  102 , and a side frame  103 . 
         [0085]    The front plate  101  may be provided on the front side of the door assembly  100 . At least a part of the front plate  101  may include a transparent material, such as glass. 
         [0086]    The rear plate  102  may be provided on the rear side of the door assembly  100 . The rear plate  102  may be arranged a certain distance apart back from the front plate  101 . The rear plate  102  and the front plate  101  may form an inner space of the door assembly  100 . At least a part of the rear plate  102  may include a transparent material, such as glass. 
         [0087]    The side frame  103  may be arranged on both sides of the inner space formed between the front plate  101  and the rear plate  102 . The side frame  103  may be combined with the front plate  101  and the rear plate  102 , such that the rear plate  101  is fixedly installed a distance apart back from the front plate  101 . 
         [0088]    The side frame  103  may include a first side frame  103   a  and a second side frame  103   b.  The first side frame  103   a  and the second side frame  103   b  may be installed to face each other on the left and right sides, respectively, between the front plate  101  and the rear plate  102 . 
         [0089]    The side frame  103  may further include a side flow-in unit  104 . The side flow-in unit  104  may serve as a passage for outdoor air to flow into the inner space of the door assembly  100  through the side frame  103 . For example, the side flow-in unit  104  may be formed on the front of the side frame  103 . The side flow-in unit  104  may be formed to extend along the front plate  101  upward or downward from a point at which the front plate  101  and the side frame  103  come into contact. Accordingly, outdoor air may flow in to the front of the inner space through the side flow-in unit  104  of the door assembly  100 . 
         [0090]    The side flow-in unit  104  may include a first side flow-in unit  104   a  formed on the first side frame  103   a,  and a second side flow-in unit  104   b  formed on the second side frame  103   b.  The first and second side flow-in units  104   a  and  104   b  may be formed to face each other. 
         [0091]    The door assembly  100  may further include a top cover  107 . The top cover  107  may be situated on the top of the door assembly  100 . The top cover  107  may be combined with the respective tops of the front plate  101 , the rear plate  102 , and the side frame  103 , thus covering the top of the inner space of the door assembly  100 . 
         [0092]    A flow-out hole  108  may be formed on at least a side of the top cover  107 . For example, the flow-out hole  108  may be formed on the top of the top cover  107 . There may be a plurality of flow-out holes  108  formed on the top of the top cover  107  at regular intervals. Alternatively, the flow-out hole  108  may be formed on the rear side of the top cover  107 . 
         [0093]    For example, the flow-out hole  108  may be formed on a location to face the cooling fan fluid path  59 . The flow-out hole  108  may serve as a passage for heated air inside the door assembly  100  to flow out of the oven  1 . The air passing through the flow-out hole  108  and moving upward of the door assembly  100  may be released out of the oven  1  with the air discharged from the cooling fan fluid path  59 . 
         [0094]    The door assembly  100  may include a bottom flow-in unit  125  (of  FIG. 5 ). The bottom flow-in unit  125  may serve as a passage for outdoor air to flow in to the inside of the door assembly  100 . For example, in the door assembly  100 , the bottom flow-in unit  125  may be provided in a way that the bottom face of the door assembly  100  is open. 
         [0095]    The door assembly  100  may further include a handle  109 . The handle  109  may be installed on the front side of the door assembly  100 . The handle  109  may be provided in a way that protrudes forward from the front side of the door assembly  100 . 
         [0096]      FIG. 5  is a side cross-sectional view of a door assembly, according to an embodiment of the present disclosure. 
         [0097]    Referring to  FIGS. 2 to 5 , the door assembly  100  may further include a first inner plate  111 . The first inner plate  111  may divide the inner space of the door assembly  100 . The first inner plate  111  may be arranged in the inner space at a position to face the rear side of the door assembly  100 . The first inner plate  111  may be positioned in parallel with the rear plate  102 . At least a part of the first inner plate  111  may include a transparent material, such as glass. 
         [0098]    The first inner plate  111  may form a first fluid path  121  with the rear plate  102 . The first fluid path  121  may be formed at a position to face the rear plate  102  of the door assembly  100 , and provide a space for air movement from the bottom toward the top. The first fluid path  121  may have a first distance d 1  between the first inner plate  111  and the rear plate  102 . 
         [0099]    The door assembly  100  may further include a second inner plate  112 . The second inner plate  112  may be arranged in the inner space of the door assembly  100  to be positioned between the first inner plate  111  and the front plate  101 . The second inner plate  112  may divide a space between the first inner plate  111  and the front side of the door assembly  100 . The second inner plate  112  may be provided in parallel with the first inner plate  111 . At least a part of the second inner plate  112  may include a transparent material, such as glass. 
         [0100]    The second inner plate  112  may form a second fluid path  122  with the first inner plate  111 . The second fluid path  122  may be formed separately from the first fluid path  121  before the first fluid path  121 . The second fluid path  122  may provide a space for air to move from the bottom toward the top. The second fluid path  122  may have a second distance d 2  between the first inner plate  111  and the second inner plate  112 . 
         [0101]    Furthermore, the second inner plate  112  may form a third fluid path with the front plate  101 . The third fluid path  123  may be formed separately from the second fluid path  122  before the second fluid path  122 . The third fluid path  123  may have a third distance d 3  between the second inner plate  112  and the front plate  101 . 
         [0102]    For example, the first distance d 1  of the first fluid path  121  may be narrower than the second distance d 2  of the second fluid path  122 . Further, the first distance d 1  of the first fluid path  121  may be narrower than the third distance d 3  of the third fluid path  123 . 
         [0103]    The second distance d 2  of the second fluid path  122  may be wider than the first distance d 1  of the first fluid path  121  and the third distance d 3  of the third fluid path d 3 . 
         [0104]    The third distance d 3  of the third fluid path  123  may be wider than the first distance d 1  of the first fluid path  121 . The third distance d 3  of the third fluid path  123  may also be narrower than the second distance d 2  of the second fluid path  122 . 
         [0105]    The door assembly  100  may further include a holder  115 . The holder  115  may fasten the first and second inner plates  111  and  112  to the inside of the door assembly  100 . The holder  115  may include an upper holder  115   a  and a lower holder  115   b.    
         [0106]    The upper holder  115   a  may be installed on both sides of the bottom of the top cover  107 . The upper holder  115   a  may hold the respective upper parts of the first and second inner plates  111  and  112  to get them fixed. 
         [0107]    The lower holder  115   b  may be installed on the respective bottom of the first and second side frames  103   a  and  103   b.  The lower holder  115   b  may hold the respective lower parts of the first and second inner plates  111  and  112  to get them fixed. 
         [0108]      FIG. 6  shows a shielding member combined on the inner side of a door assembly, according to an embodiment of the present disclosure. 
         [0109]    Referring to  FIGS. 4 to 6 , the door assembly  100  in accordance with an embodiment of the present disclosure may further include a shielding member  113 . 
         [0110]    The shielding member  113  may be positioned between the first inner plate  111  and the rear side of the door assembly  100 . The shielding member  113  may block outdoor air from flowing in between the first inner plate  111  and the rear side of the door assembly  100 . The shielding member  113  may be in the first fluid path  121  to block circulation of the air in the first fluid path  121 . 
         [0111]    As shown in  FIG. 6 , the shielding member  113  may be formed to have a rectangular shape. The shielding member  113  may be formed to run along edges of the first inner plate  111 . The shielding member  113  may be formed in a way that surrounds edges of a space formed between the first inner plate  111  and the rear side of the door assembly  100 . The shielding member  113  may be formed to have a rectangular shape in order to shield all of the top, bottom, and both sides of the first fluid path  121 . For this, the shielding member  113  may be provided to extend to contact the four holders  115  located in the first fluid path  121 . Although not shown, the four holders may each have a fastener to hold and fix the shielding member  113 . 
         [0112]    The shielding member  113  may shield all of the top, bottom, and both sides of the first fluid path  121 . Specifically, the shielding member  113   d  may shield the bottom of the first fluid path  121  to block the air flowing in from the open bottom of the door assembly from moving into the first fluid path  121 . The shielding member  113   b,    113   c  may also shield the both sides of the first fluid path  121  to block the air flowing into the door assembly  100  through the side flow-in unit  104  from moving into the first fluid path  121 . Furthermore, the shielding member  113   a  may shield the top of the first fluid path  121  to block the air inside the first fluid path  121  from moving out of the door assembly  100 . 
         [0113]      FIG. 7  shows a modified example of the shielding member of  FIG. 6 . 
         [0114]    Referring to  FIG. 7 , a shielding member  117  may be formed to extend along the bottom side of the first inner plate  111  in a space between the first inner plate  111  and the rear side of the door assembly  100 . The shielding member  117  may be positioned to shield the bottom of the first fluid path  121 . The shielding member  117  may be formed to extend from the lower folder  115   b  on one side of the first fluid path  121  to the lower folder  115   b  on the other side. With this, the shielding member  117  may block the air flowing in from the open bottom of the door assembly from moving into the first fluid path  121 . 
         [0115]      FIG. 8  shows a modified example of the shielding member of  FIG. 6 . 
         [0116]    Referring to  FIG. 8 , a shielding member  118  may be formed to extend along the bottom and both sides of the first inner plate  111  in a space between the first inner plate  111  and the rear side of the door assembly  100 . As compared to the shielding member  113  of  FIG. 6 , the shielding member  118  has a difference in that it may have an open top. The shielding member  118  may be positioned to shield the bottom and both sides of the first fluid path  121 . The shielding member  118  may be provided in the form of connecting the upper and lower holders  115   a  and  115   b  that face each other and connecting the lower holders  115   b  on both sides. With this, the shielding member  118  may block the air flowing in from the open bottom of the door assembly  100  or through the side flow-in unit  104  from moving into the first fluid path  121   
         [0117]    In case of cleaning of the cooking room  30  during or after a cooking process, the oven  1  may often keep the inside of the cooking room  30  at a high temperature. Insulation  39  may be provided between the cooking room  30  and the panel  20  on all the sides of the cooking room  30  except for its open front for shielding heat of the cooking room  30 . However, the insulation  39  may not be provided for the door assembly  100  located on the front of the cooking room  30 , in order for outdoor air to circulate in the inner space. 
         [0118]    Specifically, the outdoor air flowing into the inner space of the door assembly  100  through the bottom flow-in unit  125  may move out of the door assembly  100  through the flow-out hole  108 . The temperature of the air inside the door assembly  100  rises due to heat exchange with the heated door assembly  100 . The air of high temperature may move upward along the inner space of the door assembly  100 , and then move outside of the door assembly  100  through the flow-out hole  108 . The air moving outside of the door assembly  100  through the flow-out hole  108  may move out of the oven  1  with the air discharged forward of the oven  1  through the cooling fan fluid path  59 . If the air moves out through the flow-out hole  108 , outdoor air may flow into the inner space of the door assembly  100  through the bottom flow-in unit  125 . With this process, the temperature of the front side of the door assembly  100  may be dropped. 
         [0119]    It may also lead to a drop in temperature of the rear side of the door assembly  100 . However, in a case of cleaning the cooking room  30  to remove foreign materials stuck to the inner wall of the cooking room  30  and the rear side of the door assembly  100  by using high temperatures of the cooking room  30 , the drop in temperature of the rear side of the door assembly  100  may lead to a decrease of the cleaning efficiency. 
         [0120]    To solve this, in an embodiment of the present disclosure, the plurality of fluid paths  121 ,  122 ,  123  may be formed in the inner space of the door assembly  100 , and among them, the first fluid path  121  may be provided with the shielding member  113  to block air circulation in the first fluid path  121 . Accordingly, outdoor air flowing in through the bottom flow-in unit  125  may move along the second and third fluid paths  122  and  123  to the flow-out hole  108  on the top, and then move outside of the door assembly  100  through the flow-out hole  108 . Heat exchange may occur by continuous circulation of the outdoor air through the second and third fluid paths  122  and  123 . This may result in a larger drop in the temperature of the front plate  101 , top cover  107 , and side frame  103  of the door assembly  100 , which are located close to the second and third fluid paths  122  and  123 , than that of the rear plate  102 . 
         [0121]    As for the rear plate  102  of the door assembly  100  with the structure as discussed above, since air circulation in the first fluid path  121  is blocked, the temperature inside the cooking room  30  may remain the same. Even as for an attempt of cleaning the inner side of the rear plate  102  of the door assembly  100  by using high temperatures inside the cooking room  30 , the inner side of the rear plate  102  may be cleaned as same as the inner wall of the cooking room  30 . 
         [0122]    As described above, in accordance with an embodiment of the present disclosure, the inner side of the rear plate  102  of the door assembly  100  may maintain the same temperature inside the cooking room  30 , while the front plate  101 , top cover  107 , and side frame  103  of the door assembly  100  may be cooled off by circulation of the outdoor air to a user-contactable temperature. This may improve the efficiency of cleaning the inside of the cooking room  30  and the rear plate  102  of the door assembly  100 . 
         [0123]      FIG. 9  is a front view of an oven, according to an embodiment of the present disclosure, and  FIG. 10  is a side cross-sectional view of an oven, according to an embodiment of the present disclosure. 
         [0124]    As shown in  FIGS. 9 and 10 , an oven may include a casing that forms the exterior, and a cooking room located inside the casing. The structure of the casing and cooking room of  FIGS. 9 and 10  are substantially the same as that as described in connection with  FIGS. 1 to 3 , so the following description will focus on the difference between them. 
         [0125]    Referring to  FIGS. 9 and 10 , a first heating source may be installed between the top casing and the cooking room top plate, and a second heating source may be installed between the bottom casing and the cooking room bottom plate. The first and second heating sources may each have a structure for supplying heat into the cooking room by being controlled to be on or off according to the cooking mode. 
         [0126]    A machine room  31   a  containing various mechanical and electrical parts such as circuit boards (not shown) is arranged on top of the cooking room. A control panel of the machine room may include a display for displaying information about many different operations of the oven, and a controlling unit for controlling the operation of the oven. The controlling unit may use a pressure switch or a touch pad, and the display may use a Liquid Display Panel (LDP) 
         [0127]    Although the control panel in accordance with an embodiment has the controlling unit and the display separately, arrangement of the control panel and display may not be limited thereto, but a touch screen panel (TSP) having the controlling unit and the display integrated therein may be used. 
         [0128]    Detailed description that overlaps what are described in connection with  FIGS. 1 to 3  will be omitted herein. 
         [0129]      FIG. 11  is a control block diagram of an oven, according to an embodiment of the present disclosure. 
         [0130]    Referring to  FIG. 11 , the oven may include a control panel  15   a,  a temperature sensor  16   a,  a storage  17   a,  a driver  64   a,  a circulation fan  63 , a first heating source  35   a,  a second heating source  36   a,  and a controller  65   a.    
         [0131]    As described above, the control panel  15   a  may include the controlling unit  14   a  for receiving various instructions for operations of the oven, and the display  13   a  for displaying operation information of the oven for the user. 
         [0132]    In an embodiment, the controlling unit  14   a  may include a cooking mode controlling unit for receiving information regarding a cooking mode of the oven, and a cleaning mode controlling unit for receiving information regarding a cleaning mode of the oven. In an embodiment, the display  13   a  may display an operation of the heat source as a predetermined graphic image in response to an operation instruction of the oven input through the controlling unit  14   a,  or display a change in temperature of the cooking room due to operation of the heat source as a predetermined change in color. 
         [0133]    The temperature sensor  16   a  may be installed inside the cooking room for detecting temperatures in the cooking room that change according to operations of the oven. The temperature sensor  16   a  may be installed on at least one of the cooking room top plate, bottom plate, either side plate, and back plate, for periodically detecting temperature in the cooking room that changes according to operations of the oven. 
         [0134]    The temperature detected in the cooking room by the temperature sensor  16   a  may be informed to the controller, which may in turn control a graphic image to be displayed on the display  13   a  based on the temperature information collected from the temperature sensor  16   a . Detection of temperature which is performed by the temperature sensor  16   a,  and associated operation of the controller  65   a  will be described later. 
         [0135]    The temperature sensor  16   a  may be implemented with a contact temperature sensor, or a contactless temperature sensor. Specifically, the temperature sensor  16   a  may be implemented with at least one of a resistance thermometer detector (RTD) temperature sensor that uses changes in metal resistance due to changes in temperature, a thermistor temperature sensor that uses changes in semiconductor resistance due to changes in temperature, a thermo couple temperature sensor that uses electromotive forces produced at both terminals of a junction of two kinds of metal wires formed of different materials, and an Integrated Circuit (IC) temperature sensor that uses current-voltage characteristics of a P-N junction. However, the temperature sensor is not limited thereto, but may also be implemented with another type of temperature sensor able to detect temperature inside the cooking room. 
         [0136]    The storage  17   a  may store various data, programs, or applications for operating and controlling the oven. For example, the storage  17   a  may store data about a detection cycle of the temperature sensor  16   a,  operating temperature and time of e.g., the first and second heating sources in a cooking mode, revolutions per minute (RPM) of the circulation fan  63 , etc., a control program for controlling the oven, dedicated applications provided by the manufacturer by default, or universal applications downloaded from outside. 
         [0137]    The storage  17   a  may be implemented with volatile memory devices, such as Read Only Memory (ROM), Programmable Read Only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), and flash memory, non-volatile memory devices, such as Random Access Memory (RAM), hard disks or optical disks. 
         [0138]    The driver  64   a  may output driving signals to respective components of the oven. The driver  64   a  may include a circulation motor to circulate the circulation fan  63 . 
         [0139]    The controller  65   a  may control general operation of the oven and signal flows among the components of the oven, and process data. The controller  65   a  may run an operating system (OS) and various applications stored in the storage  17   a  when the user&#39;s input or a predetermined condition is met. 
         [0140]    The controller  65   a  may control the first and second heating sources, and the circulation fan  63  to cook the food contained in the oven when the user selects a cooking mode of the oven, and to clean the inside of the oven when the user selects a cleaning mode of the oven. Operation of the controller  65   a  in a cooking mode will now be described. 
         [0141]    The controller  65   a  may control operations of e.g., the first and second heating sources and the circulation fan  63  in a cooking mode to be displayed as predetermined graphic images through the display  13   a.  The form of the graphic image may vary, and the variation of the form of the graphic images may be used to display information about thermal diffusion inside the oven as well. 
         [0142]    For example, in a cooking mode for cooking food only by heat supplied from the first heating source  35   a,  a graphic image corresponding to the first heating source  35   a  may be displayed on the display  13   a.  In this case, the controller  65   a  may display heat supplied from the first heating source  35   a  being diffused inside the oven, by controlling the image corresponding to the first heating source  35   a  to be displayed as being expanded. 
         [0143]    The controller  65   a  may control a change in temperature of the cooking room due to operation of the first and second heating sources  35   a,    36   a  and the circulation fan  63  to be displayed on the display  13   a  as a predetermined change in color. More specifically, the change in temperature in the cooking room may be displayed as a change in color of the graphic image displayed on the display  13   a.    
         [0144]    For example, in the cooking mode for cooking food only by heat supplied from the first heating source  35   a,  the temperature inside the oven may rise while the heat is being supplied from the first heating source  35   a.  The controller  65   a  may then detect the temperature in the oven using information about the temperature detected by the temperature sensor  16   a  in the oven, and may display the temperature rise in the oven as a change in color of the graphic image when determining that the temperature in the oven is rising. 
         [0145]      FIGS. 12 to 15  illustrate operation of a heat source and thermal diffusion in cooking mode visualized on a display. In the other modes including a cleaning mode, similar illustration of what are displayed on the display in  FIGS. 12 to 17  may be applied. In the following description, what are displayed in a cooking mode, for example, will be described. 
         [0146]    The oven may include many different cooking modes. For example, the cooking modes may include convection mode in which the circulation fan operates, top/convection mode in which the first heating source and the circulation fan operate, bottom/convection mode in which the second heating source and the circulation fan operate, large grill mode in which the first heating source operates, convention mode in which the first and second heating sources operate, and bottom mode in which the second heating source operates, but are not limited thereto. 
         [0147]      FIG. 12  illustrates operation of the circulation fan in the convection mode, visualized on the display, and  FIG. 13  illustrates thermal diffusion due to the operation of the circulation fan in the convection mode, which is visualized on the display. 
         [0148]    As shown in  FIG. 12 , the operation of the circulation fan may be displayed as a graphic image in a donut shape. In the early stages of the operation of the circulation fan, the operation of the circulation fan may be displayed as a single graphic image as shown in  FIG. 12 , and thermal diffusion that occurs as the operation of the circulation fan continues may be displayed as a form in which several graphic images of the donut form overlap each other. The operation of the heating source and the thermal diffusion are not exclusively displayed as in  FIGS. 12 and 13 , but may be displayed as a graphic image of a circular form or in other various forms including expansion and reduction of the graphic image. 
         [0149]      FIG. 14  illustrates operation of the first heating source in the large grill mode, which is visualized on the display, and  FIG. 15  illustrates thermal diffusion due to the operation of the first heating source in the large grill mode, which is visualized on the display. 
         [0150]    As shown in  FIG. 14 , the operation of the first heating source may be displayed such that a graphic image corresponding to the first heating source is placed in the upper part of the display. The graphic image corresponding to the first heating source may include gradation of the graphic image, but is not limited thereto. 
         [0151]    In the early stages of operation of the first heating source, the operation of the first heating source may be displayed as a narrow range of graphic image, as shown in  FIG. 14 , and the thermal diffusion that occurs as the operation of the first heating source continues may be displayed as a wider range of graphic image, as shown in  FIG. 15 . 
         [0152]    Although not shown, in the top/convection mode in which the first heating source and the circulation fan operate, a graphic image of a combined form of graphic images shown in  FIGS. 12 to 15  may be displayed. In the bottom/convection mode in which the second heating source and the circulation fan operate, a graphic image of a combined form of the graphic images shown in  FIGS. 12 and 13  and the graphic image placed in the lower part of the display may be displayed. In the convention mode in which the first and second heating sources operate, a graphic image of a combined form of the graphic images shown in  FIGS. 14 and 15  and the graphic image placed in the lower part of the display may be displayed. In the bottom mode in which the second heating source operates, the graphic image placed in the lower part of the display may be displayed. The graphic image placed in the lower part of the display may have the same form as that of the graphic images shown in  FIGS. 14 and 15 , i.e., the graphic image placed in the lower part of the display may have the form of gradation and placed in the lower part of the display. 
         [0153]      FIG. 16  illustrates operation of a heat source and the rising of temperature in the oven, visualized on the display. More specifically, given that food is being cooked at about 200° C. in the convection mode, displaying the rising of temperature in the oven and the thermal diffusion process on the display is illustrated. 
         [0154]    For example, temperatures in the oven may be kept at about 30° C. in the early stages of operation of the oven, and may rise to about 200° C. over time, due to hot air supplied from the circulation fan. In this case, the display may display a graphic image in yellow-color series at about 30° C. and red-color series at about 200° C. by reflecting the change in temperature in the oven, as shown in  FIG. 16 . However, color implementations are not limited to what are illustrated in  FIG. 16 , but may include other various modifications that may be easily practiced by one of ordinary skill in the art. 
         [0155]    As the temperature in the oven rises from 30° C. to 200° C., thermal diffusion in the oven may also occur. In this case, as shown in  FIG. 16 , a form in which several graphic images of the donut shape overlap each other may be displayed on the display to visualize the thermal diffusion in the oven. 
         [0156]      FIG. 17  is a flowchart illustrating a method for controlling an oven, according to an embodiment of the present disclosure. The oven may be separately controlled in respective modes, but in the following description, a control process of the oven will be focused on a cooking mode. 
         [0157]    Referring to  FIG. 17 , a method for controlling the oven may include receiving a cooking mode (operation  130 ), controlling a heat source to operate according to the cooking mode (operation  132 ), detecting a temperature in the cooking room (operation  134 ), displaying operation of the thermal source and the temperature of the cooking room (operation  136 ), and displaying a change in operation of the heat source or a change in temperature of the cooking room in the cooking mode (operations  138  and  140 ). 
         [0158]    First, upon reception of a cooking mode, a series of operations are performed. 
         [0159]    Specifically, heat source may operate in the cooking mode. For example, if the convection mode is input, a circulation fan may be rotated. 
         [0160]    Once the heat source starts to operate, a temperature sensor arranged in the oven may detect a temperature in the cooking room. The temperature sensor may periodically detect temperatures in the cooking room, and output the detection result to the controller. 
         [0161]    Next, a display may display the temperature in the cooking room and the operation of the heat source. The heat source as herein used may include the first and second heating units and the circulation fan, as described above, and the form of the graphic image may be determined depending on initially input mode. 
         [0162]    For example, in the convection mode, a graphic image corresponding to the operation of the circulation fan may be displayed and the graphic image may come in a color that corresponds to the temperature in the cooking room. 
         [0163]    According to one or more embodiments of the present disclosure, cleaning efficiency of the inside of a cooking room of an oven and the inner side of a door of the oven may be improved. 
         [0164]    A door assembly with an improved structure in accordance with one or more embodiments of the present disclosure may cool off the outer side of the door assembly while keeping the inner side of the door assembly at the same temperature of the inside of the cooking room. 
         [0165]    Accordingly, the inner wall of the cooking room and the inner side of the door may be efficiently cleaned by using high temperatures. 
         [0166]    Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.