Abstract:
Disclosed herein are a heater for cookers with high economical efficiency and improved performance, a method of manufacturing the same, and a cooker including the heater. The heater for cookers includes a heat-generator, and a heater body to house the heat-generator, a surface of the heater body having a prominence/depression pattern provided by surface-treating. The heater body is processed by sandblasting.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Korean Patent Application No. 2008-0121038, filed on Dec. 2, 2008 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments of the present invention relate to a cooker, and a heater useful as a heat source of cookers. 
         [0004]    2. Description of the Related Art 
         [0005]    Cookers process or cook foods by heating. As a heat source to heat foods, a gas burner, electrical heater, etc. may be used. 
         [0006]    Heaters generally used for cookers include sheath heaters, quartz heaters, halogen heaters and ceramic heaters, etc. These heaters have distinctive characteristics, advantages and disadvantages. Accordingly, taking into consideration various factors of respective heaters, such as physical properties, price, performance and installation structure, an optimum heater is applied. 
         [0007]    For example, of these, ceramic heaters have relatively high far-infrared radiation efficiency and thus heat food from the inside and have properties suited to cook food, but have deteriorated economical efficiency due to high price. On the other hand, quartz heaters are inexpensive, but have low cooking efficiency due to lower far-infrared radiation efficiency. 
       SUMMARY 
       [0008]    Therefore, it is an aspect of the present embodiments to provide a heater for cookers with high economical efficiency and improved performance. 
         [0009]    Additional aspects of the embodiments will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
         [0010]    The foregoing and/or other aspects are achieved by providing, a heater for cookers including: a heat-generator; and a heater body housing the heat-generator, the surface of the heater body having an irregular prominence/depression pattern provided by surface-treating. 
         [0011]    The surface of the heater body may be processed by sandblasting. 
         [0012]    The heater body may contain about 99% by weight or higher of silicon dioxide (SiO2). 
         [0013]    The foregoing and/or other aspects are achieved by providing, a heater for cookers including: a heat-generator; and a quartz tube housing the heat-generator, the quartz tube having a sandblasted external surface. 
         [0014]    The quartz tube may contain about 99% by weight or higher of silicon dioxide (SiO2). 
         [0015]    The foregoing and/or other aspects are achieved by providing a method of manufacturing a heater for cookers including: preparing a quartz tube; processing an external surface of the quartz tube to impart a plurality of prominences/depressions to the external surface of the quartz tube; and arranging a heat-generator in the quartz tube. 
         [0016]    The external surface of the quartz tube may be processed by sandblasting. 
         [0017]    The foregoing and/or other aspects are achieved by providing a method of manufacturing a heater for cookers, including: preparing a quartz tube containing silicon dioxide (SiO 2 ); sandblasting an external surface of the quartz tube to form prominences/depressions on the external surface of the quartz tube; and providing a heat-generator in the quartz tube. 
         [0018]    The quartz tube may contain about 99% or higher of silicon dioxide. 
         [0019]    The silicon dioxide may have a purity of about 95% or higher. 
         [0020]    The foregoing and/or other aspects are achieved by providing, a cooker including: a cooking area; and a heater to supply heat to the cooking area, the heater including a heater body having a heat-radiation surface to radiate heat to the cooking area and a heat-generator arranged in the heater body, the heat-radiation surface including a plurality of fine prominences/depressions. 
         [0021]    The prominences/depressions may be formed by sandblasting. 
         [0022]    The heater body may include a quartz tube containing about 99% by weight or higher of silicon dioxide (SiO2). 
         [0023]    In accordance with the embodiments, material costs of the heater are reduced and cooking efficiency is improved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    These and/or other aspects and advantages will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0025]      FIGS. 1 and 2  are views illustrating an appearance and structure of a cooker according to one embodiment; 
           [0026]      FIG. 3  is a perspective view illustrating a heater for a cooker according to one embodiment; and 
           [0027]      FIG. 4  is a sectional view taken from the line I-I of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0028]    Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures. 
         [0029]      FIGS. 1 and 2  are views illustrating the appearance and structure of a cooker according to one embodiment. 
         [0030]    As shown in  FIGS. 1 and 2 , a cooker  1  includes a housing  10  provided with a cooking area  11 , and a door  30  hinge-bound to one side of the housing  10 , to open or close an open front of the cooking area  11 . 
         [0031]    The cooking area  11  is defined by a top plate  12 , a bottom plate  13 , two side plates  14  and a rear plate  15  and constituent components of the cooker are provided in an area between the outside of the cooking area  11  and the housing  10 . 
         [0032]    The outside of the rear plate  15  is bound to a fan cover  20 , and a convection fan  21  to circulate air through the cooking area  11  is provided interior the fan cover  20 . A convection heater  22  is provided on the external circumference of the convection fan  21 , and a fan motor  23 , bound to the convection fan  21 , is provided between the fan cover  20  and the rear plate  15  of the housing  10 . 
         [0033]    A plurality of inlet holes  15   a,  through which air enters the cooking area, are arranged on the center of the rear plate  15  facing the convection fan  21 , and a plurality of outlet holes  15   b,  through which heat is supplied to the cooking area, are arranged more proximate to the edge of the rear plate  15 . 
         [0034]    Insulating members  16  may be arranged on the outside of the top plate  12 , the bottom plate  13 , the two side plates  14  and the fan cover  20  to define the cooking area  11 , in order to insulate the cooking area  11  from the outside, and a control panel  17  to control the operation of an oven may be arranged on the top of the housing  10 . 
         [0035]    Meanwhile, a rail  14   a  to allow a rack  40  to be detachable is arranged on internal sides of the two side plates  14 . 
         [0036]    The cooker  1  includes at least one heater  50  as a heat source to radiation-heat food placed on the cooking area  11 . 
         [0037]    When food are placed on the rack  40  supported by the rail  14   a,  the door  30  is closed, and the control panel  17  is operated, the convection heater  22  heats and the convection fan  21  rotates via a fan motor  23 . As a result, air in the cooking area  11  is absorbed through the inlet holes  15   a,  is heated through the convection heater  22 , and is supplied through the outlet holes  15   b  to the cooking area  11 , and the supplied hot air cooks food, while circulating within the inside of the cooking area  11 . In addition, when the heater  50  for radiation heating is operated, the heater  50  directly radiation heats food in the cooking area  11 . Upon cooking food, the convection heater  22  and the heater  50  for radiation heating operate together to heat food. Alternatively, one of the convection heater  22  and the radiation heater  50  may operate to heat food. 
         [0038]    The radiation heater  50  may be arranged on the cooking area  11 , and for the arrangement of the radiation heater  50 , an accepting member  12   a  may be provided on the top plate  12  of the cooking area  11 . Both ends of the heater  50  pass through the accepting member  12   a,  extend to the outside of the cooking area  11  and are connected to power outside the cooking area  11 . 
         [0039]      FIG. 3  is a perspective view illustrating a heater for a cooker according to one embodiment, and  FIG. 4  is a sectional view taken from the line I-I of  FIG. 3 . 
         [0040]    As shown in  FIGS. 3 and 4 , the heater  50  includes a heat-generator  60  to generate heat when power is applied thereto, and a heater body  70  to accept the heat-generator  60 . 
         [0041]    The heat-generator  60  may be made of a nickel-chromium wire or be in the form of a coil. A cap  80  is arranged on both ends of the heater body  70 , and a lead wire  61  arranged on both ends of the heat-generator  60  passes through the cap  80  and extends to the outside of the heater body  70 . 
         [0042]    The heat-generator  60  heats the heater body  70  and the heated heater body  70  heats foods by emitting a variety of wavelengths. Infrared rays are electromagnetic waves whose wavelength is longer than a red region of ultraviolet rays. Far-infrared rays refer to infrared rays having a wavelength of about 3 μm or higher. Far-infrared rays are readily absorbed by materials, and suited to cooking of food due to high resonance activity thereof to organic compounds. 
         [0043]    As shown in  FIG. 4 , the heater body  70  includes a heat-radiation surface  72  to radiate heat to the cooking area  11 , and the heat-radiation surface  72  of the heater body  70  includes a plurality of prominences/depressions  74 . The prominences/depressions  74  scatter near-infrared wavelength energy passing through the heater body  70  to convert the same into far-infrared wavelength energy and thereby to improve far-infrared radiation efficiency of the heater  50 . 
         [0044]    The prominences/depressions  74  of the heater body  70  may be finely formed by sandblasting. Sandblasting is a process in which fine sand is sprayed to a subject to be processed by a strong pressure to treat the surface of the subject. The use of sandblasting to process the heater body  70  enables control of the size of sand particles used to sandblast and thus determines optimal surface roughness of the heater body  70 . 
         [0045]    Depending on specifications of the heater  50 , e.g., the type of metals used for the heat-generator  60 , and the length or diameter of the heater body  70 , the surface roughness of the heater body  70  to maximize far-infrared radiation efficiency may be varied. When the heater body  70  is processed by sandblasting, surface roughness is readily varied by simply controlling the size of sand particles used for processing, thus easily realizing optimal surface roughness according to heater specifications. 
         [0046]    The heater body  70  may be provided in the form of a tube, and may be made of transparent quartz containing about 99% by weight or higher of silicon dioxide SiO2. The heater body  70  may be manufactured by melting silicon dioxide having a purity of about 95% or higher, followed by extrusion-molding. 
         [0047]    Far-infrared ray radiation efficiency and radiation energy in a wavelength region of about 3 μm to 30 μm were measured for two specimens having the same size heated at 500° C. The results thus obtained are shown in Table 1 below. Specimen 1 is transparent quartz containing silicon dioxide having a purity of about 95% or higher, Specimen 2 is ceramic generally used for ceramic heaters, and Specimen 3 is transparent quartz, containing silicon dioxide having a purity of about 95% or higher, whose surface is sandblasted. The experiments were carried out at ambient temperature of approximately 20 to 22° C., and relative humidity of approximately 45 to 47%. 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Far-infrared ray radiation 
                 Far-infrared ray radiation 
               
               
                   
                 efficiency 
                 efficiency (Watt/m 2 ) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Specimen 1 
                 0.673 
                 124.642 × 10 2   
               
               
                 Specimen 2 
                 0.700 
                 129.482 × 10 2   
               
               
                 Specimen 3 
                 0.698 
                 124.129 × 10 2   
               
               
                   
               
             
          
         
       
     
         [0048]    As can be seen from Table 1 above, the far-infrared radiation efficiency of Specimen 3 corresponding to the embodiment is higher than that of non-surface-treated quartz (Specimen 1), and is comparable to that of Specimen 2. 
         [0049]    Specimen 3 corresponding to the embodiment is cheaper than Specimen 2 and is thus more economical. The heater  50  according to the embodiment has advantages of both economical efficiency and performance. 
         [0050]    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 invention, the scope of which is defined in the claims and their equivalents.