Frost detecting apparatus, and cooling system and refrigerator having the same

Abstract

A frost detecting apparatus including a first electrode to generate an electric field in a frost detection region, a second electrode to prevent the electric field from leaking into a frost non-detection region, an insulator arranged between the first electrode and the second electrode, to insulate the first electrode, and a shield arranged around an exposed portion of the insulator, to prevent the electric field from leaking into the frost non-detection region through the exposed portion of the insulator. As the same potential is established at the first and second electrodes, it is possible to prevent electric field from leaking into a frost non-detection region through side surfaces of the first electrode. Accordingly, the electric field is varied only by frost formed in a frost detection region, so that it is possible to more accurately detect formation of frost and the amount of the formed frost.

1 . A frost detecting apparatus comprising:
 a first electrode to generate an electric field in a frost detection region;   a second electrode to prevent the electric field from leaking into a frost non-detection region;   an insulator arranged between the first electrode and the second electrode, to insulate the first electrode; and   a shield arranged around an exposed portion of the insulator, to prevent the electric field from leaking into the frost non-detection region through the exposed portion of the insulator.   
     
     
         2 . The frost detecting apparatus according to  claim 1 , wherein the shield is electrically connected to the second electrode. 
     
     
         3 . The frost detecting apparatus according to  claim 2 , wherein the shield surrounds side surfaces of the insulator. 
     
     
         4 . The frost detecting apparatus according to  claim 3 , wherein the shield extends around side surfaces of the first electrode. 
     
     
         5 . The frost detecting apparatus according to  claim 2 , wherein the shield is spaced apart from the first electrode such that an insulating gap is defined between the shield and the first electrode, to insulate the first electrode. 
     
     
         6 . The frost detecting apparatus according to  claim 2 , wherein the shield is formed integrally with the second electrode. 
     
     
         7 . The frost detecting apparatus according to  claim 6 , wherein the second electrode is bent toward the insulator such that at least one outer portion of the second electrode surrounds the insulator. 
     
     
         8 . The frost detecting apparatus according to  claim 1 , wherein the same potential is established at the first and second electrodes. 
     
     
         9 . The frost detecting apparatus according to  claim 1 , wherein the same potential is established at the shield and the first electrode. 
     
     
         10 . The frost detecting apparatus according to  claim 1 , further comprising:
 a second insulator formed on an outer surface of the second electrode.   
     
     
         11 . The frost detecting apparatus according to  claim 10 , wherein an object, for which detection of frost formation will be performed, is in contact with an outer surface of the second insulator. 
     
     
         12 . The frost detecting apparatus according to  claim 1 , wherein the shield prevents the electric field generated in the frost detection region from varying in spite of a variation in dielectric constant caused by a variation in ambient temperature around the insulator. 
     
     
         13 . A frost detecting apparatus comprising:
 a first electrode to generate an electric field in a frost detection region;   a shield laterally arranged around the first electrode such that the shield surrounds the first electrode while being insulated from the first electrode, to prevent the electric field from leaking into a frost non-detection region through a side surface of the first electrode;   an insulator arranged in contact with a back surface of the first electrode and a back surface of the shield; and   a second electrode arranged in contact with a back surface of the insulator, to prevent the electric field from leaking into the frost non-detection region through the back surface of the first insulator.   
     
     
         14 . The frost detecting apparatus according to  claim 13 , further comprising:
 a conductor to electrically connect the shield and the second electrode.   
     
     
         15 . The frost detecting apparatus according to  claim 14 , wherein the conductor extends from the second electrode around the insulator, to laterally surround the insulator. 
     
     
         16 . The frost detecting apparatus according to  claim 13 , further comprising:
 at least one hole extending through the insulator, and a conductor formed in the hole,   wherein the conductor prevents the electric field from leaking into the frost non-detection region through at least one of the side surface of the first electrode and a side surface of the insulator.   
     
     
         17 . The frost detecting apparatus according to  claim 16 , wherein the at least one hole comprises at least four holes formed along the side surface of the insulator, and connected to the second electrode. 
     
     
         18 . The frost detecting apparatus according to  claim 13 , wherein the same potential is established at the second electrode, the first electrode, and the shield. 
     
     
         19 . The frost detecting apparatus according to  claim 13 , wherein:
 the shield is spaced apart from the first electrode, to define an insulating gap between the shield and the first electrode;   the first electrode is connected to a sensor terminal; and   the second electrode and the shield are connected to a shield terminal.   
     
     
         20 . The frost detecting apparatus according to  claim 13 , further comprising:
 a second insulator formed on a back surface of the second electrode; and   the second insulator insulates the first electrode, to prevent the first electrode from being eroded by moisture.   
     
     
         21 . The frost detecting apparatus according to  claim 14 , wherein the conductor extends from the second electrode such that the conductor laterally surrounds the insulator. 
     
     
         22 . The frost detecting apparatus according to  claim 13 , wherein the frost non-detection region is a region where an electric field generated by the first electrode in an opposite direction to an electric field generated in the frost detecting region by the first electrode is established. 
     
     
         23 . A frost detecting apparatus comprising:
 a plate-shaped first electrode to generate an electric field in a frost detection region;   a plate-shaped first insulator arranged in contact with a back surface of the first electrode;   a plate-shaped second electrode arranged in contact with the first insulator, to prevent the electric field from leaking through the back surface of the first electrode;   a plate-shaped second insulator arranged in contact with a back surface of the second electrode; and   a shield to prevent the electric field from leaking through a side surface of the first insulator,   wherein the shield is formed to laterally surround the first insulator.   
     
     
         24 . The frost detecting apparatus according to  claim 23 , wherein the shield extends along side surfaces of the first electrode. 
     
     
         25 . The frost detecting apparatus according to  claim 23 , wherein:
 the shield is electrically connected to the second electrode; and   the shield has a plate structure bent to surround the first insulator and the first electrode.   
     
     
         26 . The frost detecting apparatus according to  claim 23 , wherein the same potential is established at the shield and the first electrode. 
     
     
         27 . A cooling system comprising an evaporator mounted with a first cooling fin and a second cooling fin, further comprising:
 a frost detecting apparatus comprising
 a first electrode arranged to face the first cooling fin, the first electrode generating an electric field in a region between the first electrode and the first cooling fin, to detect formation of frost, 
 a first insulator arranged at a back surface of the first electrode, 
 a second electrode arranged at a back surface of the first insulator, to prevent the electric field from leaking toward the second cooling fin, 
 a second insulator arranged in contact with the second cooling fin, to insulate the second cooling fin from the second electrode, and 
 a shield arranged around an exposed portion of the first insulator, to prevent the electric field from leaking toward the second cooling fin through the exposed portion of the first insulator. 
   
     
     
         28 . The cooling system according to  claim 27 , wherein:
 the shield extends along side surfaces of the first insulator; and   the shield extends to a lower level than upper ends of the side surfaces of the first insulator.   
     
     
         29 . The cooling system according to  claim 27 , further comprising:
 a detector to detect a voltage corresponding to a variation in the electric field generated between the first electrode of the frost detecting apparatus and the first cooling fin; and   a controller to control a defrosting operation, based on the voltage detected by the detector.   
     
     
         30 . The cooling system according to  claim 27 , wherein the shield extends to a region surrounding the first electrode above the exposed portion of the first insulator. 
     
     
         31 . The cooling system according to  claim 27 , further comprising:
 a voltage supplier to supply the same voltage to the first and second electrodes, thereby establishing the same potential at the first and second electrodes,   wherein the first electrode is connected to a sensor terminal, and the second electrode is connected to a shield terminal.   
     
     
         32 . The cooling system according to  claim 27 , wherein the frost detecting apparatus has a U-shaped structure having bent portions, so as to be attached to the second cooling fin facing the first cooling fin. 
     
     
         33 . The cooling system according to  claim 27 , wherein the frost detecting apparatus has a double structure comprising two frost detecting units each having the same structure as the frost detecting apparatus, the second insulators of the frost detecting units being in contact with each other. 
     
     
         34 . The cooling system according to  claim 33 , further comprising:
 a detector to detect a voltage corresponding to a variation in the electric field generated between the first electrode of the frost detecting apparatus and the first cooling fin; and   a controller to control a defrosting operation, based on the voltage detected by the detector,   wherein the controller receives, from the detector, voltages respectively corresponding to capacitances generated in the frost detecting units, sums the voltages, and controls the defrosting operation, based on the summed voltage.   
     
     
         35 . The cooling system according to  claim 27 , wherein the shield is electrically connected to the second electrode. 
     
     
         36 . The cooling system according to  claim 35 , wherein the shield comprises a plurality of holes extending through the first insulator, and a conductor formed in each of the holes, so as to electrically connect the shield to the second electrode via the conductor. 
     
     
         37 . The cooling system according to  claim 36 , wherein the shield extends to a level equal to a level of upper ends of side surfaces of the first electrode, and is spaced apart from the first electrode such that a gap is defined between the shield and the first electrode, to electrically insulate the shield from the first electrode. 
     
     
         38 . The cooling system according to  claim 27 , wherein the shield has at least one outer portion bent toward the first cooling fin to surround at least one side surface of the first insulator. 
     
     
         39 . The cooling system according to  claim 38 , wherein:
 the shield extends to a level equal to a level of upper ends of side surfaces of the first electrode;   the first insulator insulates the shield from the first electrode.   
     
     
         40 . A refrigerator comprising an evaporator mounted with a first cooling fin and a second cooling fin, further comprising:
 a frost detecting apparatus comprising   a first electrode arranged to face the first cooling fin, the first electrode generating an electric field,   a first insulator arranged at a back surface of the first electrode,   a second electrode arranged at a back surface of the first insulator, to prevent the electric field from leaking toward the second cooling fin,   a second insulator to insulate the second cooling fin from the second electrode,   a shield arranged around an outer peripheral surface of the first insulator, to prevent the electric field from leaking toward the second cooling fin through the outer peripheral surface of the first insulator, and   an insulating gap to insulate the shield and the first electrode from each other.   
     
     
         41 . The refrigerator according to  claim 40 , wherein the shield is formed integrally with the second electrode. 
     
     
         42 . The refrigerator according to  claim 40 , wherein:
 the shield is laterally spaced apart from the first electrode;   the shield comprises a plurality of holes extending through the first insulator; and   each of the holes electrically connects the shield and the second electrode.   
     
     
         43 . The refrigerator according to  claim 40 , wherein the shield further comprises a conductor formed along side surfaces of the first insulator, to electrically connect the shield to the second electrode. 
     
     
         44 . The refrigerator according to any one of  claims 41 , wherein the shield extends to a level equal to a level of upper ends of side surfaces of the first electrode.