Abstract:
A cooking appliance is disclosed. The cooking appliance includes a cabinet defining the external appearance of the cooking appliance, a cooking unit provided in the cabinet for performing cooking using a heat source, a panel having a through hole, a heat source control unit provided at the rear of the panel, the heat source control unit having a shaft extending to the front of the panel through the through hole, a knob provided at the front of the panel in a state of being connected to the shaft for rotating the shaft according to user&#39;s manipulation, a knob ring provided between the knob and the panel for receiving at least a portion of the knob, and a knob ring holder coupled to the knob ring at the rear of the panel for allowing the knob ring to move on a front surface of the panel in a radial direction of the knob ring.

Description:
[0001]    This application claims the benefit of Korean Patent Application No. 10-2015-0033978, filed on Mar. 11, 2015, which is hereby incorporated by reference as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a cooking appliance, particularly to a cooking appliance configured such that a heat source control unit is manipulated using a rotary knob, and more particularly to a cooking appliance configured such that the restraint of a rotary knob or a shaft of a heat source control unit connected with the rotary knob is prevented. 
         [0004]    2. Discussion of the Related Art 
         [0005]    Cooking appliances are products that cook food using electricity or other kinds of energy at home. 
         [0006]    Among cooking appliances, there are a gas stove, a gas oven, and a gas oven/stove, which use gas. In the gas stove, the gas oven, and the gas oven/stove, food is cooked using the combustion of gas. In addition, there are a microwave oven and a microwave oven/stove, which use electricity. Of course, one cooking appliance may use multiple kinds of energy, such as both electricity and gas. 
         [0007]      FIG. 1  is a side view showing a general oven/stove, which is an example of such a cooking appliance. Of course, the cooking appliance shown in  FIG. 1  may be a cooking appliance according to an embodiment of the present invention. That is,  FIG. 1  is merely an illustration for describing the construction of a general cooking appliance. 
         [0008]    As shown in  FIG. 1 , a cooking appliance  10  or an oven/stove includes a cabinet  20  defining the external appearance of the cooking appliance. In the cabinet  20  may be defined a chamber  25  for receiving food to be cooked. Of course, the chamber  25  may be omitted from the cooking appliance  10 . 
         [0009]    A cooktop  26 , on which cooking containers are placed, may be provided at the upper side of the cabinet  20 . That is, cooking containers, such as pots, may be located on the cooktop  26  such that cooking is performed using heat generated from underneath the cooktop. 
         [0010]    The chamber  25  or the cooktop  26  may be a cooking unit, in which cooking is performed using heat generated from gas or electricity. Based on the kind of cooking appliance, various cooking units may be provided. For example, the cooking unit may be configured such that cooking is performed through the direct use of heat generated from gas or through the radiation or conduction of heat generated from gas. 
         [0011]    The cabinet  20  may be provided at the front thereof with a door  50  for opening and closing the chamber  25 . A handle  60  may be provided at the door  50 . A user may open and close the door  50  while holding the handle  60 . 
         [0012]    The cooking appliance may include a panel  30 , which may be integrally formed with the cabinet  20  or may be coupled to the cabinet  20 . The panel  30  may be provided with a manipulation unit for allowing a user to control the cooking appliance. 
         [0013]    The manipulation unit may be configured to supply heat generated from gas, to stop the supply of heat generated from gas, and to adjust the intensity of heat generated from gas. Of course, the manipulation unit may also be configured to drive an electric heater or to adjust the amount of heat that is generated by the electric heater. The manipulation unit may include a timer. In addition, the manipulation unit may further include a display part for informing the user of cooking information or a current state of the cooking appliance. 
         [0014]    The panel  30  may be provided with a knob  40 . The knob  40  may be configured to supply heat generated from gas or to drive the electric heater according to the user&#39;s manipulation. That is, the knob  40  is an example of the manipulation unit. The knob  40  may be manipulated to adjust the amount of heat that is supplied. 
         [0015]    For example, the user may manipulate the knob  40  in order to supply heat generated from gas into the chamber or to supply heat generated from gas to a specific one selected from among a plurality of cooking elements. Consequently, a plurality of knobs  40  may generally be provided as the manipulation unit. 
         [0016]    Each knob  40  may generally be connected to a shaft (see  FIG. 3 ) of a heat source control unit (see  FIG. 3 ) located at the rear of the panel  30 . The knob  40  may generally be rotated in order to supply heat generated from gas or to drive the electric heater. The motion of the knob  40  may be transmitted to the heat source control unit through the shaft. As a result, heat generated from gas may be supplied to the chamber or a specific one of the cooking elements, or the electric heater may be driven. 
         [0017]    As shown in  FIG. 1 , the panel  30  may be provided at the front of the cabinet  20 . Alternatively, the panel  30  may be provided at the top of the cabinet. As shown in  FIG. 1 , the panel  30  may be provided in an inclined state. Alternatively, the panel  30  may be provided vertically. Consequently, the position and attitude of the knob  40  may be changed depending upon the position or shape of the panel  30 . 
         [0018]    In recent years, there have been provided cooking appliances in which the knob  40  is made of an aluminum material or a zinc material in consideration of safety and design. That is, the knob  40  has been manufactured using a metal material in order to improve the design of the knob  40  by imparting the gloss of metal. In addition, the knob  40  has been manufactured such that the knob  40  is too heavy for children to easily manipulate the knob  40 . 
         [0019]    In many cases, the knob  40  may be oriented vertically at the front of the cooking appliance. This means that the shaft is oriented horizontally, i.e. parallel to the ground. For this reason, the shaft may be deformed or deviated positionally. Such deformation or positional deviation (eccentricity) of the shaft may cause the restraint of the shaft. As a result, the rotation of the shaft may be restrained. 
         [0020]    The restraint of the shaft may frequently occur when the knob  40  is heavy. In particular, when the shaft is oriented horizontally, the restraint of the shaft may occur more frequently. 
         [0021]    Meanwhile, in a case in which a knob ring is used as in an embodiment of the present invention, as will hereinafter be described, the knob  40  may be restrained by the knob ring. This is because the center of the knob may deviate from the center of the knob ring in a state in which the knob ring is not moved. Such restraint may occur due to deformation or eccentricity of the shaft. Therefore, there is a high necessity for a cooking appliance configured such that the restraint of the knob or the shaft is prevented. 
       SUMMARY OF THE INVENTION 
       [0022]    Accordingly, the present invention is directed to a cooking appliance that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
         [0023]    An object of the present invention is to provide a cooking appliance configured such that the restraint between a knob and a shaft of a heat source control unit is prevented. 
         [0024]    Another object of the present invention is to provide a cooking appliance configured such that the deformation or eccentricity of a shaft of a heat source control unit is prevented. 
         [0025]    Another object of the present invention is to provide a cooking appliance configured such that the restraint of a knob is prevented even when a shaft of a heat source control unit is eccentrically mounted during an assembly process. 
         [0026]    Another object of the present invention is to provide a cooking appliance configured such that the restraint of a knob is prevented even when the knob is relatively heavy. 
         [0027]    Another object of the present invention is to provide a cooking appliance that can be easily and simply assembled. 
         [0028]    Another object of the present invention is to provide a cooking appliance configured such that the eccentricity of a knob and a shaft of a heat source control unit is compensated for. 
         [0029]    A further object of the present invention is to provide a cooking appliance exhibiting improved reliability and durability. 
         [0030]    Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0031]    To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a cooking appliance includes a cabinet defining the external appearance of the cooking appliance, a cooking unit provided in the cabinet for performing cooking using a heat source, a panel having a through hole, a heat source control unit provided at the rear of the panel, the heat source control unit having a shaft extending to the front of the panel through the through hole, a knob provided at the front of the panel in a state of being connected to the shaft for rotating the shaft according to a user&#39;s manipulation, a knob ring provided between the knob and the panel for receiving at least a portion of the knob, and a knob ring holder coupled to the knob ring at the rear of the panel for allowing the knob ring to move on a front surface of the panel in a radial direction of the knob ring. 
         [0032]    In another aspect of the present invention, a cooking appliance includes a cabinet defining the external appearance of the cooking appliance, a cooking unit provided in the cabinet for performing cooking using a heat source, a panel having a through hole, a heat source control unit provided at the rear of the panel, the heat source control unit having a shaft extending to the front of the panel through the through hole, a knob provided at the front of the panel in a state of being connected to the shaft for rotating the shaft according to a user&#39;s manipulation, a knob ring provided between the knob and the panel for receiving at least a portion of the knob, and a knob ring holder connected to the knob ring for allowing the movement of the knob ring such that the center of the knob ring is aligned with the center of the knob. 
         [0033]    The knob ring holder may be connected to the knob ring in order to prevent the knob ring from being separated from the panel. That is, the knob ring and the knob ring holder may be coupled to each other such that the knob ring and the knob ring holder are not separated from the panel. That is, as long as any one of the knob ring, the knob ring holder, and the panel is not damaged, the knob ring and the knob ring holder are not separated from the panel. The knob ring holder may allow the knob ring to move relative to the panel while preventing the knob ring from being separated from the panel. 
         [0034]    The knob ring holder may be coupled to the knob ring at the rear of the panel for allowing the knob ring to move on the front surface of the panel in the radial direction of the knob ring. The knob ring holder may be located at the rear surface of the panel and configured to allow the knob ring to move in the radial direction at the front surface of the panel. In some cases, the knob ring holder may be located at the front surface of the panel. 
         [0035]    The heat source may be gas or electricity. Correspondingly, the heat source control unit may be a gas valve or a regulator. The gas valve may supply gas or interrupt the supply of gas, and may change the pressure of gas that is supplied in order to change the amount of heat that is supplied. The regulator may supply electric power or interrupt the supply of electric power, and may increase or decrease current or voltage in order to change the amount of heat that is supplied. The shaft is provided in order to turn the heat source control unit ON or OFF or to control the amount of heat that is supplied. The larger the rotational angle of the shaft, the larger the amount of heat that is supplied. The knob may be provided in order to easily manipulate the shaft. 
         [0036]    A user may manipulate the knob in order to control the heat source control unit using the shaft. For this reason, if the knob is restrained by the knob ring, it may be difficult for the user to manipulate the knob. 
         [0037]    The knob ring holder may allow the movement of the knob ring such that the center of the knob ring is aligned with the center of the knob. That is, the knob ring holder may allow the knob ring to move relative to the panel in the radial direction. As a result, the centers of the knob and the knob ring may be aligned. 
         [0038]    External force may be applied to the knob ring due to misalignment between the center of the knob and the center of the knob ring holder, and the knob ring and the knob ring holder may move simultaneously as a single body. Consequently, the knob ring and the knob ring holder may be coupled to each other to constitute a single body. 
         [0039]    The knob ring holder may include a base, a coupling part protruding from the base in a forward direction so as to be coupled to the knob ring, a through part for allowing the shaft to extend therethrough, and a tight contact part provided at the base so as to be brought into tight contact with the rear surface of the panel. The tight contact part may include a leaf spring. Alternatively, the tight contact part may be a leaf spring itself. 
         [0040]    The leaf spring may be integrally formed with the base. That is, the base and the leaf spring may be made of a plastic material, and the base and the leaf spring may be integrally formed. As a result, the knob ring holder may be a single structural element. 
         [0041]    A plurality of leaf springs may be arranged in a circumferential direction. As a result, the knob ring holder may be securely supported at the panel without positional deviation. 
         [0042]    Each of the leaf springs may protrude from the base in an arc shape, and may be configured such that the width of each of the leaf springs in the circumferential direction is greater than the width of each of the leaf springs in the radial direction. 
         [0043]    The base may be provided with rectangular holes or incised parts, each of which has a relatively large width in the circumferential direction, and each of the leaf springs may be formed so as to interconnect opposite sides of a corresponding one of the holes or the incised parts in the circumferential direction. 
         [0044]    Consequently, each of the leaf springs may be formed in a belt shape extending in the circumferential direction. The belt shape may be configured such that the width of belt shape in the circumferential direction is greater than the width of the belt shape in the radial direction. For this reason, the rotation of the knob ring holder may be more easily performed than the movement of the knob ring holder in the radial direction. The rotation of the knob ring holder may be negligible due to the shape of the knob ring holder. In the same manner, the rotation of the knob ring may be negligible due to the shape of the knob ring. That is, symmetry of the knob ring and the knob ring holder in the circumferential direction may be maintained due to the circular shape of the knob ring and the knob ring holder even when the knob ring and the knob ring holder are rotated. 
         [0045]    The movement of the knob ring holder in the radial direction may be more difficult than the rotation of the knob ring holder due to the shape of the leaf springs. As a result, the knob ring holder may be prevented from easily moving in the radial direction when a small force is applied thereto. 
         [0046]    The coupling part may be coupled to the knob ring through the through hole, and the outer diameter defined by the coupling part may be less than the inner diameter of the through hole. 
         [0047]    A plurality of coupling parts may be provided, and a range of the movement of the knob ring may be restricted by the distance between each of the coupling parts and the through hole in the radial direction. That is, the movement of the knob ring holder in the radial direction may be performed until the coupling parts are caught in through hole. As a result, the distance that the knob ring holder moves in the radial direction may be restricted. 
         [0048]    One of the knob ring and the knob ring holder may have a coupling part configured to be inserted through the through hole, the other of the knob ring and the knob ring holder may have a coupling hole for allowing the coupling part to be coupled therein, and the outer diameter defined by the coupling part may be smaller than the inner diameter of the through hole such that the coupling part is allowed to move in the through hole in the radial direction. This may mean that a range of the movement of the coupling part is restricted by the inner diameter of the through hole. 
         [0049]    The through part, configured to allow the shaft to extend therethrough, may be located at the center of the base, and a plurality of coupling parts may be arranged in the circumferential direction of the through part. Each of the coupling parts may be a hook having a curved outer surface corresponding to the through hole. Since the curved outer surfaces of the coupling parts are brought into contact with the through hole, the coupling parts or the through hole may be prevented from being damaged. 
         [0050]    The knob ring may include a ring-shaped frame having an opening formed at the front part thereof such that at least a portion of the knob is received in the frame and a rear wall provided at the rear part of the frame such that the rear wall is brought into tight contact with the front surface of the panel. 
         [0051]    The rear wall may include a through part formed at the center of the rear wall for allowing the shaft to extend therethrough and a coupling hole for allowing the coupling part to be coupled thereto. 
         [0052]    The panel may be provided with a guide hole, formed outside the through hole, and the knob ring may be provided with an insertion protrusion, configured to be inserted through the guide hole. The insertion protrusion may be inserted through the guide hole such that the knob ring and the knob ring holder are temporarily coupled to each other. 
         [0053]    The guide hole and the insertion protrusion may be provided in ones. That is, only one guide hole may be provided outside the through hole in the radial direction. The reason for this is that if two or more guide holes and two or more insertion protrusions are provided, the movement of the knob ring and the knob ring holder in the radial direction may be restrained due to coupling between the guide holes and the insertion protrusions. 
         [0054]    The guide hole may be located at the left or right of the through hole such that the center of the guide hole is aligned with the center of the through hole, and the guide hole may be formed in a long hole shape having a relatively large width in a leftward and rightward direction. More specifically, the center of the guide hole and the center of the through hole may form a horizontal line. 
         [0055]    The insertion protrusion may move in the long hole in the leftward and rightward direction due to the characteristics of the long hole. This may mean that the knob ring holder may move relative to the panel in the leftward and rightward direction. 
         [0056]    In a further aspect of the present invention, a cooking appliance includes a cabinet defining the external appearance of the cooking appliance, a cooking unit provided in the cabinet for performing cooking using a heat source, a panel having a through hole, a heat source control unit provided at the rear of the panel, the heat source control unit having a shaft extending to the front of the panel through the through hole, a knob provided at the front of the panel in a state of being connected to the shaft for rotating the shaft according to user&#39;s manipulation, a knob ring provided at the front surface of the panel for allowing the knob to rotate while surrounding the knob at the outside of the knob in a radial direction, and a knob ring holder coupled to the knob ring at the rear of the panel, wherein the knob ring holder includes a tight contact part configured to be elastically deformed in a state of being brought into tight contact with the rear surface of the panel for allowing the knob ring holder and the knob ring to move in the radial direction. 
         [0057]    The cooking unit may be a cooktop or a chamber. 
         [0058]    It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0059]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
           [0060]      FIG. 1  is a side view showing a general cooking appliance or a gas oven/stove that is applicable to an embodiment of the present invention; 
           [0061]      FIG. 2  is a perspective view showing a panel of a conventional cooking appliance or a cooking appliance that is applicable to an embodiment of the present invention; 
           [0062]      FIG. 3  is an exploded perspective view showing a panel according to an embodiment of the present invention in a state in which a knob is separated from the panel; 
           [0063]      FIG. 4  is a front perspective view showing a state in which a knob ring and a knob ring holder according to an embodiment of the present invention are coupled to each other; 
           [0064]      FIG. 5  is a side sectional view showing a state in which the knob ring and the knob ring holder according to the embodiment of the present invention are coupled to each other; 
           [0065]      FIG. 6  is a front perspective view of the knob ring holder according to the embodiment of the present invention; 
           [0066]      FIG. 7  is a rear perspective view of the knob ring holder shown in  FIG. 6 ; 
           [0067]      FIG. 8  is a front perspective view showing a knob ring holder according to another embodiment of the present invention; and 
           [0068]      FIG. 9  is a rear perspective view of the knob ring holder shown in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0069]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
         [0070]      FIG. 2  is a perspective view showing a panel  100  of a conventional cooking appliance or a panel of a cooking appliance according to an embodiment of the present invention. For the convenience of description, other constructions of the cooking appliance, such as a cabinet and a cooking unit, are omitted from  FIG. 2 . The cooking appliance according to the embodiment of the present invention may be identical or similar to the conventional cooking appliance in terms of the external appearance of the front part of the panel. 
         [0071]    The panel  100  shown in  FIG. 2  may be applied to a gas oven/stove. Similarly, the panel  100  may also be applied to a gas stove or a gas oven. Hereinafter, an embodiment of a gas oven/stove will be described as an example of the cooking appliance. Of course, the panel  100  may also be applied to an electric oven/stove or an electric stove. 
         [0072]    The panel  100  may be provided therein with a plurality of through holes  110 . A knob  200  may correspond to each of the through holes  110 . Consequently, the panel  100  may be provided with a plurality of knobs  200 . The panel  100  shown in  FIG. 2  may be provided with four cooktop knobs and one oven knob  200 . In addition, the panel  100  may be provided with a timer through hole  120 . An identical or similar knob may be provided at the front of the timer through hole  120 . The timer through hole  120  may have a smaller diameter than the other through holes  110 . 
         [0073]    The panel  100  may be provided with a window  130 , in which a display unit is mounted. 
         [0074]    A knob ring  300  may be provided between the knob  200  and the panel  100 . The knob ring  300  may keep the knob  200  in tight contact with the panel  100  in order to prevent moisture or foreign matter from being introduced into the panel  100  through the through hole  110 . In addition, the knob  200  may be received in a portion of the front of the knob ring  300 . Consequently, the knob  200  may be rotatable relative to the knob ring  300 . 
         [0075]    The knob ring  300  may be located around the knob  200  to protect the knob  200  and to prevent moisture or foreign matter from being introduced into the panel  100  through the knob  200 . 
         [0076]    Specifically, the knob ring  300  may be provided at a front surface  111  of the panel  100 . In addition, the knob  200  may be provided at the front of the panel  100  in a state in which at least a portion of the knob  200  is received in the knob ring  300 . As a result, it is possible for a user to easily manipulate the knob  200  from the front of the cooking appliance. 
         [0077]    Hereinafter, the panel according to the embodiment of the present invention will be described in more detail with reference to  FIGS. 3 to 5 . 
         [0078]      FIG. 3  is an exploded perspective of the panel  100  shown in  FIG. 2  in a state in which the knob  200  and the knob ring  300  are separated from the panel  100 . Unlike the conventional panel, in this embodiment, it is possible to effectively prevent the restraint of a shaft by the provision of a knob ring holder  400 . In addition, it is possible to effectively prevent the knob  200  from being restrained by the knob ring  300 . 
         [0079]    Specifically, the knob ring  300  may be located at the front surface  111  of the panel  100 , and the knob ring holder  400  may be located at a rear surface  112  of the panel  100 . That is, the knob ring  300  may be located at the front of the through hole  110  formed at the panel  100 , and the knob ring holder  400  may be located at the rear of the through hole  110 . The knob ring  300  and the knob ring holder  400  may be coupled to each other in a state in which the panel  100  is interposed between the knob ring  300  and the knob ring holder  400 . Consequently, the knob ring holder  400  may be an element for coupling the knob ring  300  to the panel  100 . 
         [0080]    A heat source control unit  500  is located at the rear of the panel  100 . The heat source control unit  500  is provided with a shaft  530 . The shaft  530  extends from the heat source control unit  500  so as to protrude to the front of the through hole  110 . The shaft  530  is coupled to the knob  200  at the front of the panel  100 . When the knob  200  is rotated, therefore, the shaft  530  may also rotate. 
         [0081]    The shaft  530  may be rotated to manipulate the heat source control unit  500 . The heat source control unit  500  may be a gas valve or a regulator. When the shaft  530  is rotated, the gas valve may be opened, or an electric heater may be driven. As a rotational angle of the shaft  530  is increased, the amount of heat that is generated may increase. Of course, the gas valve or the regulator is a structural element that is generally used in cooking appliances. 
         [0082]    A portion of the knob  200  is received in the knob ring  300 . As shown in  FIG. 2 , a portion of the rear part of the knob  200  may be rotated in a state of being received in the knob ring  300 . 
         [0083]    The knob ring  300  may be provided with a through part  310 . The knob ring holder  400  may also be provided with a through part  410 . The through parts  310  and  410  may be formed at the centers of the knob ring  300  and the knob ring holder  400 , respectively. The through parts  310  and  410  may be configured such that the shaft  530  extends through the through parts  310  and  410 . Consequently, at the rear of the panel  100 , the shaft  530  may sequentially extend through the through part  410  of the knob ring holder  400 , the through hole  110  of the panel  100 , and the through part  310  of the knob ring  300 , and may then be coupled to the knob  200 . Basically, the shaft  530  may constitute the centers of the knob  200 , the knob ring  300 , and the knob ring holder  400 . As will hereinafter be described, however, the shaft  530  may be deformed or deviated positionally due to external force that is applied through the knob  200 . The knob  200  may deviate from the center of the through hole  110  due to such positional deviation (e.g. eccentricity). 
         [0084]    Hereinafter, a relationship between the knob ring  300  and the knob ring holder  400  will be described in detail with reference to  FIGS. 4 and 5 . 
         [0085]      FIG. 4  is a front perspective view showing a state in which the knob ring  300  and the knob ring holder  400  are coupled to each other, and  FIG. 5  is a side sectional view showing a state in which the knob ring  300  and the knob ring holder  400  are coupled to each other. 
         [0086]    As previously described, the knob ring  300  and the knob ring holder  400  are coupled to each other. That is, the knob ring  300  and the knob ring holder  400  may be mechanically coupled to each other. The knob ring holder  400  may be a structural element that is coupled to the knob ring  300  to fix the knob ring  300  to the panel  100 . However, the knob ring  300  may not be completely fixed to the panel  100  by the knob ring holder  400 . 
         [0087]    In general, the knob ring  300  is fixed to the panel  100  using screws. As long as the screws or the knob ring  300  is not damaged, therefore, the knob ring  300  is securely fixed to the panel  100 . The movement of the knob ring  300  is restrained, whereas the center of the knob  200  may be moved by eccentricity of the shaft  530  or external force applied to the shaft  530 . In other words, the knob  200  moves relative to the knob ring  300  in a radial direction, resulting in the eccentricity of the shaft  530 . 
         [0088]    That is, the center of the knob ring  300  and the center of the knob  200  may not be aligned. As a result, a portion of the knob  200  may be caught in the knob ring  300 . In this state, it may be difficult for the user to manipulate the knob  200 . 
         [0089]    However, the knob ring holder  400  according to the embodiment of the present invention may be a structural element for fixing the knob ring  300  to the panel  100  such that the knob ring  300  is allowed to move in a radial direction. Of course, it is necessary to prevent the knob ring  300  from moving easily when a small external force is applied in the radial direction. A concrete example of the knob ring holder  400  that accomplishes this will hereinafter be described. 
         [0090]    First, the knob ring  300  and the knob ring holder  400  may be coupled to each other through various mechanical coupling structures. Screw coupling or hook coupling may also be used. In this embodiment, the knob ring  300  and the knob ring holder  400  are coupled to each other by hook coupling. The knob ring  300  and the knob ring holder  400  may be coupled to each other through various mechanical coupling structures as long as the knob ring  300  and the knob ring holder  400  can move simultaneously as a single body. 
         [0091]    As shown in  FIG. 4 , the knob ring  300  is provided with a coupling hole  350 . Correspondingly, the knob ring holder  400  is provided with a coupling part  450 . The knob ring  300  and the knob ring holder  400  are coupled to each other by inserting the coupling part  450  through the coupling hole  350 . Of course, an example of the coupling part  450  may be a hook. 
         [0092]    When the coupling part  450  is inserted through the coupling hole  350 , the knob ring  300  and the knob ring holder  400  substantially constitute a single assembly. When one of the knob ring  300  and the knob ring holder  400  moves relative to the panel  100  in a radial direction, the other of the knob ring  300  and the knob ring holder  400  also moves relative to the panel  100  in the radial direction. 
         [0093]    As shown in  FIG. 5 , the knob ring  300  and the knob ring holder  400  are coupled to each other in a state in which the panel  100  is interposed between the knob ring  300  and the knob ring holder  400 . That is, the knob ring  300  is located at the front surface  111  of the panel  100 , and the knob ring holder  400  is located at the rear surface  112  of the panel  100 . Consequently, the coupling part  450  of the knob ring holder  400  may be coupled to the knob ring  300  through the panel  100 . Of course, the positions at which the coupling part  450  and the coupling hole  350  are formed may be reversed. That is, the coupling part may be formed at the knob ring  300 , and the coupling hole may be formed at the knob ring holder  400 , such that the coupling part of the knob ring  300  is inserted through the coupling hole of the knob ring holder  400  through the panel  100 . 
         [0094]    When the knob ring  300  and the knob ring holder  400  are coupled to each other, the knob ring  300  and the knob ring holder  400  may be brought into tight contact with the panel  100 . That is, the knob ring  300  may be brought into tight contact with the front surface  111  of the panel  100 , and the knob ring holder  400  may be brought into tight contact with the rear surface  112  of the panel  100 . 
         [0095]    The coupling part  450  of the knob ring holder  400  may be inserted through the through hole  110  of the panel  100 . That is, the coupling part  450  may extend from the rear surface  112  of the panel  100  to the front surface  111  of the panel  100  via the through hole  110  of the panel  100 . For secure coupling between the knob ring  300  and the knob ring holder  400 , the knob ring  300  may be provided with a plurality of coupling holes  350 , and the knob ring holder  400  may be provided with a plurality of coupling parts  450 . The coupling holes  350  and the plurality of coupling parts  450  may be arranged symmetrically in a circumferential direction. In one example, two or four pairs of coupling holes and coupling parts may be provided. 
         [0096]    Meanwhile, all of the coupling parts  450  may be inserted through the through hole  110  of the panel  100 . Consequently, an outer diameter d (see  FIG. 6 ) of a circle defined by the coupling parts  450  may be smaller than an inner diameter D of the through hole  110  of the panel  100 . 
         [0097]    The difference between the inner diameter D and the outer diameter d is set such that the coupling parts  450  are inserted through the through hole  110  of the panel  100  in a state in which the movement of the coupling parts  450  in the radial direction is allowed. That is, the knob ring  300  and the knob ring holder  400 , which includes the coupling parts  450 , may move simultaneously due to the difference between the inner diameter D and the outer diameter d. 
         [0098]    For example, in a state in which the center of the knob ring holder  400 , the center of the knob ring  300 , and the center of the through hole  110  of the panel  100  are aligned, the difference between the inner diameter D and the outer diameter d may be 10 mm. Consequently, the knob ring  300  and the knob ring holder  400  may move from the center of the through hole  110  of the panel  100  by up to 5 mm in the radial direction. That is, the knob ring  300  and the knob ring holder  400  may move relative to the panel  100  in the radial direction due to the difference between the inner diameter D and the outer diameter d. In other words, the knob ring  300  and the knob ring holder  400  may move upward, downward, leftward, and rightward in the radial direction. Considering a direction of gravity and a direction of external force depending upon how the knob  200  is used, the knob ring  300  and the knob ring holder  400  may move in the direction of gravity, i.e. in the radial direction, in most cases. 
         [0099]    In an initial state, i.e. a state in which the shaft  530  or the knob  200  is not eccentric, however, the center of the knob ring  300  must be aligned with the center of the through hole  110  of the panel  100 . That is, when the knob ring  300  and the knob ring holder  400  are assembled to the panel  100 , the centers of the knob ring  300 , the knob ring holder  400 , and the through hole  110  of the panel  100  may be aligned. 
         [0100]    After the center of the knob ring  300  is approximately aligned with the center of the through hole  110  of the panel  100 , therefore, the knob ring  300  and the knob ring holder  400  may be coupled to each other. 
         [0101]    To this end, the knob ring  300  may be provided with an insertion protrusion  360 , as shown in  FIG. 5 . A guide hole  121 , through which the insertion protrusion  360  is inserted, may be formed at the panel  100 , as shown in  FIG. 3 . The guide hole  121  may be formed outside the through hole  110  of the panel  100  in the radial direction. 
         [0102]    As shown in  FIG. 3 , the center of the guide hole  121  may be aligned with the center of the through hole  110  of the panel  100 . Only one insertion protrusion  360  may be formed at the knob ring  300 . Correspondingly, only one guide hole  121  may be formed at the panel  100 . That is, only one guide hole  121  may be provided for each through hole  110  of the panel  100 . 
         [0103]    When the insertion protrusion  360  is inserted through the guide hole  121 , the center of the knob ring  300  may be approximately aligned with the center of the through hole  110  of the panel  100 . This is because one side of the knob ring  300  is temporarily fixed as a result of the insertion protrusion  360  being inserted through the guide hole  121 , and, at this time, a user may move the other side of the knob ring  300  such that one side of and the other side of the knob ring  300  are level with each other. 
         [0104]    In other words, when the insertion protrusion  360  is inserted through the guide hole  121 , the knob ring  300  may be rotated about the guide hole  121 . The user may perceive the approximate position of the guide hole  121  even though the user cannot see the guide hole  121 . This is because the user may perceive the position of the center of rotation of the knob ring  300  by sensitively rotating the knob ring  300 . 
         [0105]    The rotating operation may be repeated several times such that the position opposite the insertion protrusion  360  (i.e. the position symmetric with the insertion protrusion  360  on the basis of the center of the knob ring  300 ) may be level with the position of the insertion protrusion  360 . In this way, the center of the knob ring  300  may be approximately aligned with the center of the through hole  110  of the panel  100  even though the user cannot see the center of the through hole  110  of the panel  100  due to the knob ring  300 . In this state, the knob ring holder  400  is coupled to the knob ring  300  at the rear of the panel  100 . That is, the knob ring holder  400  is coupled to the knob ring  300  at the rear of the panel  100 , and the movement of the knob ring  300  in the radial direction on the front surface of the panel  100  is allowed. More specifically, the knob ring  300  and the knob ring holder  400 , which are coupled to each other, move relative to the panel in the radial direction of the knob ring  300 . This means that the movement of the knob  200  relative to the panel  100  in the radial direction causes the movement of the knob ring  300  and the knob ring holder  400  relative to the panel  100  in the radial direction. In contrast, the movement of the knob ring  300  and the knob ring holder  400  relative to the panel  100  in the radial direction may cause the movement of the knob  200  relative to the panel  100  in the radial direction. 
         [0106]    Consequently, the knob ring  300  and the knob ring holder  400  are eccentrically placed due to the eccentricity of the knob  200 , whereby the centers of the knob  200 , the knob ring  300 , and the knob ring holder  400  are aligned with one another. In contrast, the knob  200  is eccentrically placed due to the eccentricity of the knob ring  300  and the knob ring holder  400 , whereby the centers of the knob  200 , the knob ring  300 , and the knob ring holder  400  are aligned with one another. As a result, the restraint between the knob  200  and the knob ring  300  may be prevented. 
         [0107]    As previously described, the center of the guide hole  121  may be aligned with the center of the through hole  110  of the panel  100 . This is because a direction in which the knob  200  is restrained, a direction in which external force is applied to the knob  200 , a direction in which the shaft  530  is deformed, and a direction of gravity may be considered, and the knob ring  300  and the knob ring holder  400  substantially move in the radial direction, particularly in the upward and downward directions. 
         [0108]    That is, a range in which the movement of the knob ring  300  and the knob ring holder  400  is allowed may be set such that the knob ring  300  and the knob ring holder  400  can move a relatively large distance in the upward and downward direction, but can move only a relatively small distance in the leftward and rightward directions. 
         [0109]    As previously described, the insertion protrusion  360  is inserted through the guide hole  121 . For this reason, the movement of the knob ring  300  relative to the panel  100  in the leftward and rightward direction may be restrained. As shown in  FIG. 3 , therefore, the guide hole  121  may be formed to have a long hole shape configured such that the width in the leftward and rightward directions is greater than the width in the upward and downward directions. Due to the width of the guide hole  121  in the leftward and rightward directions, the extent to which the knob ring  300  and the knob ring holder  400  can move in the leftward and rightward directions may be restrained. Of course, the extent to which the knob ring  300  and the knob ring holder  400  can move in the leftward and rightward directions may be less than the extent to which the knob ring  300  and the knob ring holder  400  can move in the upward and downward directions. This is because the insertion protrusion  360  constitutes the center of rotation of the knob ring  300 . 
         [0110]    Consequently, the extent to which the knob ring  300  and the knob ring holder  400  can move in the upward and downward directions (D/2−d/2) may be greater than the extent to which the knob ring  300  and the knob ring holder  400  can move in the leftward and rightward directions, which is restrained by the shape of the guide hole  121 . As a result, the knob ring  300  and the knob ring holder  400  are allowed to move radially relative to the panel  100  in upward, downward, leftward, and rightward directions. Of course, the width of the movement of the knob ring  300  and the knob ring holder  400  may be restricted depending upon the difference between the diameters D and d and the position and the shape of the guide hole  121 . As a result, it is possible to prevent excessive movement of the knob ring  300  and the knob ring holder  400 . 
         [0111]    As shown in  FIG. 4 , the knob ring  300  may include a ring-shaped frame  340 . An opening  341  may be formed at the front part of the ring-shaped frame  340  such that a portion of the knob  200  is received in the frame  340 . The knob  200  may be formed in a circular shape, which corresponds to the shape of the frame  340 . The knob  200  may be rotated in the frame  340 . 
         [0112]    The knob ring  300  may include a rear wall  330  provided at the rear part of the frame  340  such that the rear wall  330  is brought into tight contact with the front surface  111  of the panel  100 . At least a portion of the rear wall  330  may be brought into tight contact with the front surface  111  of the panel  100 . 
         [0113]    The through part  310  may be formed through the center of the rear wall  330 . The shaft  530  may extend through the through part  310 . A hub  320  may be formed around the through part  310 . The hub  320  may be formed at the center of the rear wall  330 , and the through part  310  may be formed through the center of the hub  320 . The hub  320  may protrude in a forward direction by a predetermined length. Consequently, the hub  320  may surround a predetermined length of the shaft  530 , which extends through the through part  310 . As a result, it is possible to more stably support the shaft  530 . 
         [0114]    The coupling holes  350  may be formed at the rear wall  330 . The coupling holes  350  may be formed outside the through part  310  or the hub  320  in the radial direction. Consequently, the radius of a circle defined by the coupling holes  350  may be greater than that of the through part  310  or the hub  320 . As a result, the knob ring  300  may be more securely coupled to the panel  100  or the knob ring holder  400 . 
         [0115]    Hereinafter, an embodiment of the knob ring holder  400  will be described in detail with reference to  FIGS. 6 and 7 . 
         [0116]    The knob ring holder  400  is configured to allow the movement of the knob ring  300  in the radial direction. In addition, the knob ring holder  400  is coupled to the knob ring  300  at the rear of the panel  100 . 
         [0117]    The knob ring holder  400  allows the movement of the knob ring  300  such that the center of the knob ring  300  is aligned with the center of the knob  200 . That is, the knob ring holder  400  allows the movement of the knob ring  300  in the radial direction. When the center of the knob  200  moves in the radial direction, the knob  200  is brought into tighter contact with the knob ring  300 . As a result, the knob  200  is restrained. In addition, the knob  200  pushes the knob ring  300  in the same radial direction. That is, external force is applied to the knob ring  300  due to misalignment between the center of the knob  200  and the center of the knob ring  300  or the knob ring holder  400 . As a result, the knob ring  300  and the knob ring holder  400  move simultaneously. That is, the knob ring holder  400  allows the knob ring  300  to move in response to the external force. In other words, when the knob  200  moves in a specific direction, the knob ring  300  also moves in the same direction, whereby the centers of the knob  200  and the knob ring  300  are aligned with each other. As a result, tight contact between the knob  200  and the knob ring  300  is prevented, and, at the same time, the restraint of the knob  200  and the knob ring  300  is prevented. 
         [0118]    The knob ring holder  400  may include a base  420 . The base  420  may be formed in a circular shape. The knob ring holder  400  may further include a tight contact part  430  protruding from the base  420  in a forward direction so as to be coupled to the knob ring  300 . When the knob ring  300  and the knob ring holder  400  are coupled to each other, the tight contact part  430  is brought into tight contact with the rear surface  112  of the panel  100 . In a state of being brought into tight contact with the rear surface  112  of the panel  100 , the tight contact part  430  generates frictional force, by which the movement of the knob ring holder  400  in the radial direction is restrained. When external force that is greater than the frictional force is applied, the knob ring holder  400  may move in the radial direction. That is, the knob ring holder  400  may move only when external force having a predetermined magnitude is applied. This means that the knob ring  300  may move in the radial direction only when external force having a predetermined magnitude is applied to the knob ring  300 . 
         [0119]    The tight contact part  430  may include a leaf spring. Consequently, the tight contact part  430  may be elastically deformed in a direction in which the tight contact part  430  is pushed. The direction in which the tight contact part  430  is pushed may be a direction in which the knob ring  300  and the knob ring holder  400  are coupled to each other. Consequently, the knob ring  300  and the knob ring holder  400  may be coupled to each other as a result of the tight contact part  430  being deformed. 
         [0120]    Hereinafter, the tight contact part  430  will be described as being a leaf spring. Consequently, the leaf spring may be denoted by the same reference numeral  430 . 
         [0121]    The leaf spring may be elastically deformed as a result of the coupling between the knob ring  300  and the knob ring holder  400 . That is, the leaf spring may be pressed down against the rear surface  112  of the panel  100  with the result that the leaf spring may be elastically deformed. The greater the deformation of the leaf spring, as shown in  FIG. 5 , the larger the area of the leaf spring that contacts the rear surface  112  of the panel  100 . The increase of contact area may cause the increase of frictional force. Consequently, the knob ring  300  and the knob ring holder  400  may be securely fixed to the panel  100 . The knob ring  300  and the knob ring holder  400  may move in the radial direction only when external force having a predetermined magnitude (i.e. external force greater than frictional force) is applied. 
         [0122]    The tight contact part  430  or the leaf spring may be integrally formed with the base  420 . That is, the knob ring holder  400  may be made of a plastic material, and the base  420  and the leaf spring may be integrally formed. 
         [0123]    A plurality of leaf springs  430  may be arranged in a circumferential direction. The leaf springs  430  may be arranged symmetrically in a circumferential direction of the knob ring holder  400 . 
         [0124]    Each of the leaf springs  430  may protrude from the base  420  in an arc shape, and may be configured such that the width of each of the leaf springs  430  in the circumferential direction is greater than the width of each of the leaf springs  430  in the radial direction. When force is applied to each of the leaf springs  430  such that the height of the arc of each of the leaf springs  430  is reduced, each of the leaf springs  430  may be elastically deformed due to the shape-based characteristics thereof. 
         [0125]    Specifically, as shown in  FIG. 6 , the base  410  may be provided with rectangular holes  440 , each of which has a relatively large width in the circumferential direction. That is, each of the rectangular holes  440  may be configured such that the width of each of the rectangular holes  440  in the circumferential direction is greater than the width of each of the rectangular holes  440  in the radial direction. Each of the leaf springs  430  may be formed so as to bridge opposite sides of a corresponding one of the rectangular holes  440  in the circumferential direction. That is, each of the leaf springs  430  may be formed so as to protrude in a forward direction (i.e. toward the panel  100 ) in an arc shape. 
         [0126]    The coupling parts  450  may be formed at the central part of the base  420 . As previously described, each of the coupling parts  450  may be a hook. The through part  410  may be located inside the coupling parts  450  in the radial direction. 
         [0127]    The coupling parts  450  may be formed outside the through part  410  in the radial direction such that the coupling parts  450  are arranged in the circumferential direction. A circle defined by the outer surfaces of the coupling parts  450  may have a specific outer diameter d. As previously described, the outer diameter d may be less than the inner diameter D of the through hole  110  of the panel  100 . In addition, all of the outer surfaces of the coupling parts  450  may be curved. That is, the outer diameter d is defined by the curved surfaces of the coupling parts  450 . 
         [0128]    Even when the outer surfaces of the coupling parts  450  come into contact with the through part  410 , therefore, impact and friction may be dispersed due to the characteristics of the curved surfaces of the coupling parts  450 . As a result, it is possible to prevent the through part  410  or the through hole  110  from being damaged. 
         [0129]    Hereinafter, another embodiment of the knob ring holder  400  will be described with reference to  FIGS. 8 and 9 . 
         [0130]    This embodiment is similar to the previous embodiment except that the structure of the leaf springs  430  of this embodiment is different from that of the leaf springs  430  of the previous embodiment. 
         [0131]    In this embodiment, the base  420  may be provided with incised parts, each of which has a relatively large width in the circumferential direction. For the convenience of description, the incised parts are denoted by the same reference numeral as the holes  440  of the previous embodiment. 
         [0132]    Each of the leaf springs  430  may be formed so as to interconnect opposite sides of a corresponding one of the incised parts in the circumferential direction. Consequently, the leaf springs  430 , which are elastically deformable, in the identical manner to those of the previous embodiment, may be integrally formed with the base  420 . 
         [0133]    In this embodiment, the base  420  may be formed to have a flat surface. On the other hand, the base  420  of the previous embodiment may be folioed to have a stepped surface. The structure of the base  420  may differ depending upon the required rigidity of the base  420 . In a case in which the base  420  has a stepped surface, it is possible to increase the rigidity of the base  420 . In this case, however, the structure of the knob ring holder  400  may be complicated. 
         [0134]    The movement of the knob ring  300  in the radial direction may be allowed by the knob ring holder  400  having the leaf springs  430  configured as described above. That is, the knob ring  300  may move in a direction in which eccentricity or restraint of the knob ring  300  is prevented. In addition, the distance that the knob ring  300  moves may be structurally restricted. 
         [0135]    Restraint between the knob ring  300  and the knob  200  may occur due to a very small eccentricity, and such small eccentricity may be solved by the movement of the knob ring  300 . Consequently, it is possible to prevent restraint between the knob ring  300  and the knob  200 . 
         [0136]    As is apparent from the above description, according to an embodiment of the present invention, it is possible to provide a cooking appliance configured such that the restraint between a knob and a shaft of a heat source control unit is prevented. 
         [0137]    According to an embodiment of the present invention, it is possible to provide a cooking appliance configured such that the deformation or eccentricity of a shaft of a heat source control unit is prevented. 
         [0138]    According to an embodiment of the present invention, it is possible to provide a cooking appliance configured such that the restraint of a knob is prevented even when a shaft of a heat source control unit is eccentrically mounted during an assembly process. 
         [0139]    According to an embodiment of the present invention, it is possible to provide a cooking appliance configured such that the restraint of a knob is prevented even when the knob is relatively heavy. 
         [0140]    According to an embodiment of the present invention, it is possible to provide a cooking appliance that can be easily and simply assembled. 
         [0141]    According to an embodiment of the present invention, it is possible to provide a cooking appliance configured such that the eccentricity of a knob and a shaft of a heat source control unit is compensated for. 
         [0142]    According to an embodiment of the present invention, it is possible to provide a cooking appliance exhibiting improved reliability and durability. 
         [0143]    It will be apparent to those skilled in the art that various modif i cations and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.