Refrigerator

Abstract

A refrigerator includes a cabinet forming a storage space, a door configured to open and close the storage space and define an ice-making chamber, an ice-maker provided in the ice-making chamber, and a controller configured to control the ice-maker. The ice-maker includes an upper tray made of a metal material and having a plurality of upper cells, a lower tray mounted to be movable with respect to the upper tray and having a plurality of lower cells that forms spaces, in which ice is made, together with the upper cells, a heater configured to heat the upper tray to perform a preheating operation for separating the ice, and a temperature sensor configured to measure a temperature of the upper tray. The controller is configured to determine whether the preheating operation is completed based on the temperature measured by the temperature sensor.

What is claimed is: 
     
         1 . A refrigerator comprising:
 a cabinet forming a storage space;   a door configured to open and close the storage space and define an ice-making chamber;   an ice-maker provided in the ice-making chamber; and   a controller configured to control the ice-maker,   wherein the ice-maker comprises:
 an upper tray made of a metal material and having a plurality of upper cells, 
 a lower tray mounted to be movable with respect to the upper tray and having a plurality of lower cells that forms spaces, in which ice is made, together with the upper cells, 
 a heater configured to heat the upper tray to perform a preheating operation for separating the ice, and 
 a temperature sensor configured to measure a temperature of the upper tray, and 
   wherein the controller is configured to determine whether the preheating operation is completed based on the temperature measured by the temperature sensor.   
     
     
         2 . The refrigerator according to  claim 1 , wherein the controller is configured to control the heater so that the heater performs the preheating operation when ice-making is completed, and
 wherein, in a process of the preheating operation, the controller is configured to:
 determine whether the preheating operation is completed when a preheating completion determination start condition is satisfied; and 
 control the ice-maker to perform an ice separation operation when a preheating completion condition is satisfied. 
   
     
     
         3 . The refrigerator according to  claim 2 , wherein, in the preheating completion determination start condition, when a first temperature measured at a first time point, and a second temperature measured at a second time point after a first period from the first time point are compared with each other, the second temperature is greater than the first temperature. 
     
     
         4 . The refrigerator according to  claim 3 , wherein each of the first temperature and the second temperature is below zero. 
     
     
         5 . The refrigerator according to  claim 3 , wherein, in the preheating completion condition, when a third temperature measured at a third time point in a situation, in which the preheating completion determination start condition is satisfied, and a fourth temperature measured at a fourth time point after a second period from the third time point are compared with each other, the third temperature and the fourth temperature are the same. 
     
     
         6 . The refrigerator according to  claim 5 , wherein the third temperature is an average temperature measured during a third period from the third time point, and
 wherein the fourth temperature is an average temperature measured during a third period from the fourth time point.   
     
     
         7 . The refrigerator according to  claim 6 , wherein each of the third temperature and the fourth temperature is in a range of about −1° C. or more and about 1° C. or less. 
     
     
         8 . The refrigerator according to  claim 2 , wherein, in the preheating completion determination start condition, the heater operates continuously for a predetermined operation time or more. 
     
     
         9 . The refrigerator according to  claim 8 , wherein, in the preheating completion condition, when a first temperature measured at a first time point in a situation, in which the preheating completion determination start condition is satisfied, and a second temperature measured at a second time point after a preheating completion period from the first time point are compared with each other, the first temperature and the second temperature are the same. 
     
     
         10 . The refrigerator according to  claim 9 , wherein the first temperature is an average temperature measured during a predetermined measurement period from the first time point, and
 wherein the second temperature is an average temperature measured during the predetermined measurement period from the second time point.   
     
     
         11 . The refrigerator according to  claim 10 , wherein each of the first temperature and the second temperature is in a range of about −1° C. or more and about 1° C. or less. 
     
     
         12 . The refrigerator according to  claim 2 , further comprising a motor unit configured to rotate the lower tray,
 wherein the controller is configured to control the motor unit to be driven when the preheating completion condition is satisfied.   
     
     
         13 . The refrigerator according to  claim 1 , wherein the temperature sensor is configured to provide the measured temperature to the controller in real time,
 wherein the controller is configured to control the heater such that the heater performs the preheating operation when ice-making is completed,   wherein, in a process of the preheating operation, the controller is configured to control the ice-maker such that an ice separation operation is performed when a preheating completion condition is satisfied, and   wherein, in a preheating completion determination start condition, a temperature provided from the temperature sensor in real time is maintained for a predetermined preheating completion period.   
     
     
         14 . The refrigerator according to  claim 1 , wherein the heater is disposed on a top surface of the upper tray, and
 wherein the temperature sensor is disposed to be in contact with the upper tray and is spaced apart from the heater.