Cooling apparatus and frost detecting method thereof

Abstract

A cooling apparatus including a frost sensor to sense frost, a multiplexer having a first input terminal, to which the frost sensor is connected, and a second input terminal as a non-connected input terminal, a signal processor to subtract a signal input through the second input terminal from a signal input through the first input terminal, and to output a signal obtained by the subtraction, and a controller to detect an amount of frost sensed by the frost sensor, based on the output signal from the signal processor. It is possible to easily and accurately determine noise contained in a signal received from the frost sensor by determining, as noise, the signal received from the input terminal, to which the frost sensor is not connected, and subtracting the noise from the signal received from each input terminal, to which the frost sensor is connected.

1 . A cooling apparatus comprising:
 a frost sensor to sense frost;   a multiplexer having a first input terminal, to which the frost sensor is connected, and a second input terminal as a non-connected input terminal;   a signal processor to subtract a signal input through the second input terminal from a signal input through the first input terminal, and to output a signal obtained by the subtraction; and   a controller to detect an amount of frost sensed by the frost sensor, based on the output signal from the signal processor.   
     
     
         2 . The cooling apparatus according to  claim 1 , wherein a peripheral noise signal is input to the second input terminal. 
     
     
         3 . The cooling apparatus according to  claim 1 , wherein the signal processor removes a noise signal by subtracting the signal input through the second input terminal from a frost sensing signal as the signal input through the first input terminal. 
     
     
         4 . The cooling apparatus according to  claim 1 , wherein:
 the controller controls a defrosting operation based on the detected frost amount; and   the cooling apparatus further comprises a heater to operate in accordance with a command from the controller, so as to execute the defrosting operation.   
     
     
         5 . The cooling apparatus according to  claim 1 , further comprising:
 a filter to allow a low-frequency signal component of a frost sensing signal generated by the frost sensor to pass through the filter.   
     
     
         6 . The cooling apparatus according to  claim 1 , wherein the signal processor allows a low-frequency signal component of a frost sensing signal generated by the frost sensor to pass through the signal processor. 
     
     
         7 . The cooling apparatus according to  claim 1 , wherein the signal processor converts an analog signal as a frost sensing signal generated by the frost sensor into a digital signal. 
     
     
         8 . The cooling apparatus according to  claim 1 , wherein the signal processor amplifies a frost sensing signal generated by the frost sensor to a predetermined level. 
     
     
         9 . The cooling apparatus according to  claim 1 , wherein the frost sensor is installed on at least one of an evaporator for a refrigerating compartment, an evaporator for a freezing compartment, and an evaporator for an ice making compartment. 
     
     
         10 . The cooling apparatus according to  claim 9 , wherein the frost sensor senses a capacitance established between cooling fins provided at the at least one evaporator. 
     
     
         11 . The cooling apparatus according to  claim 1 , further comprising:
 an oscillator to supply a voltage to the frost sensor.   
     
     
         12 . The cooling apparatus according to  claim 11 , wherein the multiplexer further has a first output terminal, to which the frost sensor is connected, and a second output terminal as a non-connected output terminal, and supplies the voltage to a selected one of the first and second output terminals. 
     
     
         13 . The cooling apparatus according to  claim 1 , wherein:
 the frost sensor comprises a plurality of sensors; and   the sensors are connected to the first output terminal and first input terminal of the multiplexer, and the sensors sequentially receive a voltage, and transmit a frost sensing signal to the first input terminal.   
     
     
         14 . A frost detecting method in a cooling apparatus, comprising:
 supplying a voltage to a frost sensor through a first output terminal of a multiplexer;   sensing frost by the frost sensor;   receiving a frost sensing signal generated by the frost sensor through a first input terminal of the multiplexer;   receiving a signal from a second input terminal of the multiplexer;   subtracting the signal of the second input terminal from the frost sensing signal; and   detecting an amount of frost, based on a signal obtained by the subtraction.   
     
     
         15 . The frost detecting method according to  claim 14 , wherein the subtraction of the signal of the second input terminal from the frost sensing signal is executed to remove a peripheral noise signal from the frost sensing signal. 
     
     
         16 . The frost detecting method according to  claim 14 , further comprising:
 determining a point in time when a defrosting operation should be begun, based on the detected frost amount;   driving a heater at the determined time point when the defrosting operation should be begun;   determining, during the defrosting operation, a point in time when the defrosting operation should be ended; and   stopping driving of the heater at the determined time point when the defrosting operation should be ended.   
     
     
         17 . The frost detecting method according to  claim 14 , further comprising:
 passing a low-frequency component of the frost sensing signal generated by the frost sensor.   
     
     
         18 . The frost detecting method according to  claim 14 , further comprising:
 converting an analog signal as the frost sensing signal generated by the frost sensor into a digital signal.   
     
     
         19 . The frost detecting method according to  claim 14 , further comprising:
 amplifying the frost sensing signal generated by the frost sensor to a predetermined level.   
     
     
         20 . The frost detecting method according to  claim 14 , wherein the sensing of frost by the frost sensor comprises sensing a capacitance established between cooling fins provided on at least one evaporator. 
     
     
         21 . The frost detecting method according to  claim 14 , further comprising:
 supplying a voltage through the second output terminal of the multiplexer.   
     
     
         22 . The frost detecting method according to  claim 14 , wherein the second output terminal and the second input terminal are non-connected terminals. 
     
     
         23 . The frost detecting method according to  claim 14 , wherein:
 the frost sensor comprises a plurality of sensors each connected to the first output terminal and first input terminal of the multiplexer; and   the supply of the voltage to the frost sensor comprises sequentially supplying the voltage to the sensors.   
     
     
         24 . The frost detecting method according to  claim 23 , wherein the reception of the frost sensing signal through the first input terminal of the multiplexer comprises sequentially receiving frost sensing signals from the sensors through the first input terminal.