Patent Publication Number: US-7910861-B2

Title: Cooking device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Korean Patent Application No. 10-2006-0112900, filed on Nov. 15, 2006, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a cooking device that can cook food by using a heat source, and more particularly, to a cooking device that includes at least one optical heater to heat forced air provided by a fan. 
     2. Description of Related Art 
     A related art cooking device is generally used for cooking food or heating objects placed in the cooking device by supplying heat from a heat source to the food or other objects placed in the cooking device. For example, the cooking device may defrost, warm, and/or sterilize food placed in a cooking cavity of the cooking device. In addition, the cooking device may also be used to heat and/or sterilize steam towels. The related art cooking device employs various kinds of heat sources so as to implement optimum cooking methods corresponding to a variety of cooking conditions, such as the type of food or object, the type of cooking method, and the type of cooking device. 
     It is required that the heat sources for the cooking device be used to cook food or heat objects placed therein, quickly and uniformly to satisfy quick response time desired by a user. It is desirable that the heat source of the cooking device should also have low manufacturing and maintenance cost, stability, ease of maintenance and control, and high durability. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses one or more of the above problems, and provides a cooking device, which can be used to visually determine whether an optical heater is operating based on light radiated from the optical heater. The optical heater provides light wave energy so that the temperature within a cooking cavity can be raised. 
     According to an aspect of the present invention, there is provided a cooking device that includes a cooking cavity, a fan located in the cooking device, the fan being configured to force air into the cooking cavity, and at least one optical heater to supply optical wave energy to heat the forced air provided by the fan. 
     In another aspect, the cooking device may include a heating chamber configured to communicate with the cooking cavity, the fan being located in the heating chamber. 
     In a further aspect, the at least one optical heater may be located in the heating chamber. 
     In still another aspect, the cooking device may include a reflector located in the heating chamber, the reflector being configured to reflect light of the at least one optical heater. 
     In yet another aspect, the at least one optical heater may be configured to surround at least a portion of the periphery of the fan. 
     In a different aspect, the at least one optical heater may be located in a flow channel of the forced air. 
     In still another aspect, the cooking cavity may include at least one protruding portion that extends towards the heating chamber. The at least one optical heater may include a pair of ends, the pair of ends being received in the at least one protruding portion. 
     In another aspect, the at least one protruding portion may include a first protruding portion, and a second protruding portion spaced opposite the first protruding portion. The at least one optical heater may include a first optical heater having one end located in the first protruding portion and the other end located in the second protruding portion and a second optical heater having one end located in the first protruding portion and the other end located in the second protruding portion. 
     In a different aspect, the cooking device may include a cover member, the heating chamber being defined by the cover member and a rear surface of the cooking cavity. 
     In another aspect, the at least one optical heater may be in the form of a rod. 
     In still another aspect, the at least one optical heater may include a main body and a plurality of projections that extend from the main body. Alternatively, the at least one optical heater may include at least one concave surface and at least one convex surface. 
     In a different aspect, the at least one optical heater may be one of a carbon heater and a halogen heater. 
     According to principles of the present invention, there is provided a cooking device that includes a cooking cavity, a fan located in the cooking device, the fan being configured to force air into the cooking cavity, and at least one carbon heater to supply optical wave energy to heat the forced air provided by the fan. 
     Additional aspects are similar to those described above. 
     Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein: 
         FIG. 1  is a perspective view of a cooking device according to a first embodiment of the present invention when a door of the cooling device is opened; 
         FIG. 2  is a front view of the cooking device of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the cooking device taken along line A-A of  FIG. 1 ; 
         FIG. 4  is an exploded perspective view of the beating components of the cooking device of  FIG. 1 ; 
         FIG. 5  is a graph showing the relationship between temperatures within a cooking cavity and the operating time of a carbon heater and a sheath heater; 
         FIG. 6  is a graph showing the relationship between energy absorption factors and wavelengths depending on the foods placed in the cooking device; 
         FIG. 7  is a graph showing the relationship between black body radiation spectra and wavelengths depending on temperatures; 
         FIG. 8  is a graph showing the relationship between the amount of radiation and surface temperatures of the heater depending on wavelengths; 
         FIG. 9  is a graph showing the relationship between radiation luminance and wavelengths of a carbon heater and a halogen heater; 
         FIG. 10  is a front view of a cooking device according to a second embodiment of the present invention; 
         FIG. 11  is a cross-sectional view of the cooking device taken along line B-B of  FIG. 10 ; and 
         FIG. 12  is an exploded perspective view of the heating components of the cooking device of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now be described in detail in connection with exemplary embodiments of cooking devices shown in the accompanying drawings. It is to be noted that a cooking device according to the present invention can be implemented through many different embodiments, some of which will now be described. 
     A first exemplary embodiment of a cooking device according to the present invention is shown in  FIGS. 1-4 . The cooking device includes a cabinet  2 , a cooking cavity  4  provided within the cabinet  2 , a door  6  for opening and closing the cooking cavity  4 , a control PCB (not shown) disposed in either the cabinet  2  or the door  4 , and a heat source supply unit for supplying heat to food or other objects placed in the cooking cavity  4 . The cooking cavity  4  has a front surface, which includes an opening to provide access to the cooking cavity  4 , opposite the door  6 , so that the front surface opening can be opened and closed by the door  6  and food or other objects can be placed in and removed from the cooking cavity  4 . While it has been noted above that food and other objects can be heated in the cooking device, all future description will relate to food being placed in the cooking device. 
     As shown in  FIGS. 2-4 , the cooking cavity  4  can have a protruding portion  4 A that extends towards a heating chamber or convection chamber  22 , which will be described in detail below. As shown in the figures, the protruding portion  4 A of the cooking cavity  4  is formed integrally with the cooking cavity  4 . In particular, when viewed from the outside of the cooking cavity  4 , a portion of a rear wall of the cooking cavity corresponding to the protruding portion  4 A of the cooking cavity  4  extends towards the inside of the cooking cavity  4 . By providing the protruding portion  4 A integrally with the cooking cavity  4 , additional processes and components for fabricating the protruding portion  4 A of the cooking cavity  4  and assembling the protruding portion  4 A and the cooking cavity  4  can be obviated. Further, since electrical components for controlling the cooking cavity  4  can be located in the protruding portion  4 A, the utilization of space can be increased. 
     At least one hole  4 B is formed in protruding portion  4 A and is configured to receive an end of an optical heater  26  disposed in the convection chamber  22  so that the end of the optical heater  26  passes through the protruding portion  4 A of the cooking cavity  4 . In this exemplary embodiment, one protruding portion  4 A and two through holes  4 B are disposed on one side of the cooking cavity  4  in order for both ends of the optical heater  26  to pass therethrough. Accordingly, the optical heater  26  can be easily connected to a control PCB (not shown) located outside the cooking cavity  4  without being bent. 
     While the cooking device has been described as having a protruding portion  4 A, the present invention is not limited to the above configurations as the protruding portion  4 A can be eliminated and the ends of the optical heater can extend through some other portion of the cooking cavity  4 . In addition, the present invention can be implemented in various ways, such as that the protruding portion  4 A is formed separately from the cooking cavity  4  and then coupled to the cooking cavity  4  using various connection techniques. 
     A rack  10 , which supports food placed in the cooking cavity  4 , can be disposed within the cooking cavity  4 . Rack rails  12 , which allow the edges of the rack  10  to be inserted or removed so that the rack  10  can be attached to or detached from the cooking cavity  4 , are disposed on the left and right inner walls of the cooking cavity  4 . A plurality of the rack rails  12  can be disposed in a vertical direction on the left and right inner walls of the cooking cavity  4 , respectively, so that the position of the rack  10  within the cooking cavity  4  can be moved upward and downward. 
     The cooking cavity heat source supply unit can be constructed to supply one or more of various kinds of heat sources, including heaters and microwaves. In particular, the heat source supply unit includes a convection module  20  for supplying heat from a heater in a forced convection manner. The convection module  20  includes the convection chamber  22  in communication with the cooking cavity  4 , a fan  24  for generating forced convection between the convection chamber  22  and the cooking cavity  4 , and an optical heater  26  disposed in the convection chamber  22  and configured to supply heat to the forced convection generated by the fan  24 . The optical heater  26  can be one of many heaters that radiate energy in the form of light, such as a halogen heater and a carbon heater. Further details of the optical heater  26  will be provided below. 
     The convection chamber  22  can be coupled directly to the cooking cavity  4  or can communicate with the cooking cavity  4  through an additional convection duct, which is spaced apart from the cooking cavity  4  and guides the forced convection generated by the fan  24 . In this first exemplary embodiment, the convection chamber  22  is directly coupled to the cooking cavity  4  and is defined by a rear wall of the cooking cavity  4  and a convection cover  21 . The convection chamber  22  is provided inside the cooking cavity  4 , as shown in the figures, or outside the cooking cavity  4 . 
     In particular, the convection cover  21  is coupled to one side of the inner wall of the cooking cavity  4  to define the convection chamber  22 . The convection cover  21  includes a base panel  21 A and a barrier panel  21 B. The base panel  21 A protrudes from the inner walls of the cooking cavity  4  towards the center of the cooking cavity  4 . The barrier panel  21 B extends from the base panel  21 A and surrounds a gap between the base panel  21 A and the inner walls of the cooking cavity  4 . In the present embodiment, the base panel  21 A has a round shape; however, the present invention is not limited to such a configuration and the base panel  21 A can have a variety of shapes such as a square or an ellipse. Further, in the present embodiment, the base panel  21 A has a flat surface; however, the present invention is not limited to such a configuration and base panel  21 A can have different shaped surfaces such as convex/concave surfaces. 
     The sectional area of the convection chamber  22  is gradually narrowed as the barrier panel  21 B goes from the inner walls of the cooking cavity  4  to the base panel  21 A. Thus, the barrier panel  21 B includes an inclined surface in which the inner walls of the cooking cavity  4  are spaced apart from the base panel  21 A. As shown in  FIG. 3 , a convection exhaust vent  21 D may be formed in the inclined surface to direct hot air from the convection chamber  22  towards the center of the cooking cavity  4 . Thus, hot air generated by the convection module  20  can be concentrated on food placed in the center of the cooking cavity  4 . 
     Convection intake vents  21 C, as shown in  FIGS. 2-4 , are provided in the front of the convection cover  21  so that the forced convection generated by the fan  24  causes air to flow from the cooking cavity  4  to the convection chamber  22 . The convection intake vents  21 C are disposed centrifugally so that the fan  24  can rotate around axis X, best seen in  FIG. 4 , to draw air in through the convection intake vents  21 C. The convection exhaust vents  21 D are formed in the convection cover so that the forced convection generated by the fan  24  can move from the convection chamber  22  to the cooking cavity  4 . The convection exhaust vents  21 D are of a centrifugal type, and can be disposed in the barrier panel  21 B in order to prevent mixing with the forced convection through the convection intake vents  21 C. A plurality of the convection exhaust vents  21 D can be disposed in the barrier panel  21 B so that the force convection by the fan  24  can be spread from the convection chamber  22  to the cooking cavity  4  quickly and uniformly. 
     While the first exemplary embodiment has been described with a fan  24  having a centrifugal form so that the forced convection can be formed from the convection intake vents  21 C to the convection exhaust vents  21 D, the present invention is not so limited. Rather, the fan  24  can be implemented in various ways such as an axial current type or a cross current type. 
     The fan  24  is rotated by a motor  25  driven by electricity. The motor  25  can also be disposed within or outside the convection chamber  22 . Further, the motor  25  can be directly connected to the fan  24  via an axis or indirectly connected thereto via a belt and pulley, a gear module of the like. 
     At least one optical heater  26  is disposed on the flow channel of the forced convection generated by the fan  24 . That is, one or more optical heaters  26  can be disposed in the convection chamber  22  or can be disposed on an additional duct that connects the convection chamber  22  aid the cooking cavity  4 . As shown in the figures, the optical heater  26  is disposed in the convection chamber  22 . When the optical heater  26  is disposed in the convection chamber  22 , it can be disposed between the fan  24  and the base panel  21 A or between the fan  24  and the barrier panel  21 B, as shown in  FIGS. 3 and 4 . The optical heater  26  can surround at least part of the fan  24 . That is, the optical heater  26  can be provided in a ring shape or can be implemented in various forms, such as a bar shape, an L shape, a H shape, a V shape, a spiral shape or a horseshoe shape. 
     The optical heater  26  can have one or more projections to provide a wide surface area relative to the size of the optical heater  26 . For example, in this first exemplary embodiment, the optical heater  26  includes a plurality of pins  26 ′ that protrude from the surface of the optical heater  26 . The pins  26 ′ can be formed separately and then combined with the optical heater  26  or formed integrally with a body of the optical heater  26 . Alternatively, the optical heater  26  can have a convex/concave pattern formed thereon in order to increase the surface area of the optical heater  26 . In other words, a plurality of grooves can be formed in the surface of the optical heater  26 . By providing a large surface area, heat exchange with the forced convection by the optical heater  26  and the fan  24  can be increased relative to the size of the optical heater  26 . Accordingly, heating efficiency can be improved. 
     The convection module  20  can also include a reflector  28  capable of reflecting light from the optical heater  26 . The reflector  28  can be located between the inner walls of the cooking cavity  4  defining the convection chamber  22  and the optical heater  26  so that the light of the optical heater  26  can be reflected from the convection chamber  22  towards the cooking cavity  4 . The reflector  28  can be attached to the inner walls of the cooking cavity  4  constituting the convection chamber  22  so as to reduce heat loss of the convection module  20  through the inner walls of the cooking cavity  4 . Alternatively, the reflector  28  can be attached to part of the inner walls of the cooking cavity  4  defining the convection chamber  22  corresponding to the size of the optical heater  26 , or can be attached to the entire inner walls of the cooking cavity  4  defining the convection chamber  22 . While the first exemplary embodiment shows only one reflector  28 , two or more reflectors  28  can be provided on the inner walls of the cooking cavity defining the convection chamber  22 . The reflector  28  can have a flat surface or can have at least one convex/concave portion formed therein. 
     The optical heater  26  supplies heat by light wave energy and has a low heat capacity. Thus, it is easy to visually determine whether the optical heater  26  is operating based on the light generated from the optical heater  26 . Further, because of the low heat capacity, a temperature within the cooking cavity  4  can be raised rapidly. A sheath heater of a conventional cooking device, on the other hand, has a much larger heat capacity and is quickly cooled by the forced convection generated by the fan  24 . Because the sheath heater does not use light to generate heat, it is difficult to visually determine whether a sheath heater is operating. Furthermore, as shown in  FIG. 5 , the optical heater in the form of a carbon heater, heats the air in the cooking cavity to a higher temperature and at a faster rate than the sheath heater can heat the air in the cooking cavity. This comparison was made by operating both the carbon heater and the sheath heater at the same power lever, in particular, 2000 watts. 
     Next, various characteristics of the respective heaters will be described with reference to  FIGS. 6 to 9 .  FIG. 6  is a graph showing the relationship between energy absorption factors and wavelengths depending on various foods placed in the cooking device. As a result of an experiment on various foods including steak, ham, potatoes, and bread, it was determined that the wavelengths of approximately 1.4 to 5 μm were effective wavelength bands for which the energy absorption factors of the various foods were good.  FIG. 7  is a graph showing the relationship between black body radiation spectra and wavelengths depending on temperatures and  FIG. 8  is a graph showing the relationship between the amount of radiation and surface temperatures of the heater depending on wavelengths. From  FIGS. 7 and 8 , it is apparent that a heater that provides a lot of radiation when operated at the effective wavelength bands of 1.4 to 5 μm of the various foods and provides a heater surface temperature of approximately 1200 to 1400° C. is advantageous. Finally,  FIG. 9  is a graph showing the relationship between radiation luminance and wavelengths depending on a carbon heater and a halogen heater. From  FIG. 9 , it can be seen that the carbon heater, at the effective wavelength bands (approximately 1.4 to 5 μm) of the various foods tested, has a greater radiation amount than the halogen heater has at the same wavelength bands. 
     The following table 1 shows surface temperatures of respective heaters based on the various foods tested, an increase in the temperature of the various foods tested, and power consumption cost. 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 halogen 
                 ceramics 
                 sheath 
                 Radiant 
                 Carbon 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Heat surface temperature (° C.) 
                 2,000 
                 1,000 
                 900 
                 900 
                 1200 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Temperature 
                 Cooking 
                 Steak 
                 31.6 
                 24.2 
                 23.1 
                   
                 26.7 
               
               
                 increase 
                 object 
                 (15 minutes) 
               
               
                 (Δ t ° C.), 
                 (cooking time) 
                 Ham 
                 27.5 
                 24.9 
                 23.6 
                   
                 30.4 
               
               
                 1200 W 
                   
                 (10 minutes) 
               
               
                   
                   
                 Potato 
                 37.0 
                 34.8 
                 29.2 
                   
                 44.0 
               
               
                   
                   
                 (15 minutes) 
               
               
                   
                   
                 Bread 
                 8.1 
                 22.8 
                 5.1 
                   
                 26.3 
               
               
                   
                   
                 (4 minutes) 
               
            
           
           
               
               
               
               
               
               
            
               
                 Power consumption cost 
                 8500 
                   
                   
                   
                 8000 
               
               
                 (V1 kW) 
               
               
                   
               
            
           
         
       
     
     Referring to  FIGS. 6 to 9  and Table 1, the optical heater  26  has a surface temperature that produces a higher radiation amount at the effective wavelength bands of the various foods tested as compared to the sheath heater. In addition, the optical heater has a relatively better effective radiation energy amount and a quicker cooking speed compared with the sheath heater. In addition, the carbon heater of the optical heaters  26  has a surface temperature that produces a higher radiation amount at the effective wavelength bands of the various foods than the halogen heater does, and thus, has a relatively more effective radiation energy amount and a faster temperature increase rate compared with the halogen heater, enabling more rapid cooking and low power consumption cost. Thus, it can be more advantageous to use carbon rather than halogen as the optical heater  26 ; however, both the halogen heater and the carbon heater are more advantageous than the sheath heater. 
     An operation of the convection module  20  of the cooking device of this first embodiment will be described below. When the convection module  20  operates, power is supplied to the motor  25  to rotate the fan  24 . Power is applied to the optical heater  26 , so that the optical heater  26  produces light. Thus, when forced convection is formed between the cooking cavity  4  and the convection chamber  22  by the fan  24 , the forced convection is heated under the influence of light wave energy from the optical heater  26 . As a result, the temperature within the cooking cavity  4  is raised and food within the cooking cavity  4  is heated. 
     A second exemplary embodiment of the cooking device according to the present invention is shown in  FIGS. 10-12 . With the exception of the features of the convection module, the remaining constituent elements and operation of the cooking device according to the present embodiment can be implemented in the same manner as the cooking device according to the first embodiment of the present invention, and repetitive descriptions will be omitted. 
     A convection module  60  of the cooking device according to the present embodiment includes a convection chamber  62  defined by a cooking cavity  50  and a convection cover  61 , a fan  64  rotated by a motor  63  within the convection chamber  62 , and a pair of bar shaped optical heaters  66  located within the convection chamber  62 . 
     A protruding portion  52  protruding toward the inner walls of the cooking cavity  50  can be disposed in the convection chamber  62 . The protruding portion  52  can correspond to a portion where the optical heater  66  is not located. In particular, a plurality of protruding portions  52  can be formed in order to allow opposite ends of the optical heater  66  to pass therethrough. That is, two protruding portions  52  can be disposed at the upper and lower sides of the convection chamber  62 , respectively. Through holes  52 A through which the optical heater  66  can pass are formed in the protruding portions  52 . 
     Convection intake vents  61 C are formed in a base panel  61 A of the convection cover  61 . Convection exhaust vents  61 D are formed in the barrier panel  61 B and are aligned with the optical heaters  66 . 
     While two optical heaters  66  are shown in the present embodiment, one or more optical heaters  66  can be disposed in the convection chamber  62 . The two optical heaters  66  can both be located at one side with respect to the fan  64 , or can be spaced apart from each other around the fan  64 , as shown in the figures. When the two optical heaters  66  are located opposite each other with respect to the fan  64 , hot air generated by the convection module  60  can be supplied uniformly to the cooking cavity  50 . As noted above, the optical heaters  66  can correspond to portions where the protruding portions  52  are not located along the circumferential direction of the fan  64 . Thus, the protruding portions  52  may serve as part of the boundary of the convection chamber  62 , guide the hot air by the convection module  60  to face the convection exhaust vents  61 D, and support the optical heaters  66 . 
     The present invention is not limited to the above embodiments, and various other changes and modifications are possible within the spirit and scope of the invention by those having ordinary skill in the art. For example, it is possible to combine the carbon heater and the halogen heater as the optical heater and selectively operate one of them depending on cooking needs. In addition, other heat sources such as other heaters and microwave sources can be added to provide additional heating functions. 
     As described above in detail, the cooking device according to the present invention employs an optical heater for supplying heat from optical wave energy. It is therefore possible to easily visually determine whether the optical heater is being operated. Further, reliability and efficiency can be improved since a temperature within a cooking cavity can be raised quickly by optical wave energy of the optical heater. Further, if the cooking device includes an optical heater having a convex/concave surface or protruding portions projecting from its surface, light wave energy from the optical heater can be transferred more easily. Accordingly, heat efficiency can be improved. 
     If the cooking device includes a reflector for reflecting light of the optical heater toward the cooking cavity, heat loss of the optical heater through the walls of the cooking cavity can be reduced, heat efficiency can be improved, and the cooking time can be shortened. Accordingly, the performance of the cooking device can be improved and the visibility of the cooking device can be enhanced by the reflector. 
     In addition, when the cooking cavity includes protruding portions extending towards the convection chamber, the optical heater can be easily connected to a circuit portion of the control PCB outside of the cooking cavity and the optical heater can be firmly supported by the protruding portions of the cooking cavity. Further, the protruding portions of the cooking cavity can serve to guide forced convection generated by the fan. 
     Furthermore, when the cooking device employs a carbon heater, good cooking characteristics can be obtained even when compared with other optical heaters, such as a halogen heater. 
     The invention thus being described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.