Washing machine and method for detecting unbalanced state of laundry therein

Abstract

A washing machine which determines an unbalanced state of laundry using an unbalance value and a variation of the unbalance value according to time so as to reduce the generation of vibration and noise, and a method for detecting the unbalanced state of the laundry therein. The washing machine includes a rotary tub containing laundry, a washing motor for rotating the rotary tub, a motor speed detecting unit detecting the speed of the washing motor and outputting a motor speed signal, and a controller calculating an unbalance value of the laundry and a variation of the unbalance value using the motor speed signal, determining the unbalanced state of the laundry in the rotary tub using the unbalance value and the variation of the unbalance value, and controlling the washing motor according to determination results.

1 . A washing machine comprising: 
 a rotary tub containing laundry therein;    a washing motor rotating the rotary tub;    a motor speed detecting unit detecting a speed of the washing motor and outputting a motor speed signal; and    a controller calculating an unbalance value of the laundry and a variation of the unbalance value using the motor speed signal, determining an unbalanced state of the laundry in the rotary tub using the unbalance value and a variation of the unbalance value, and controlling the washing motor according to determination results.    
   
   
       2 . The washing machine as set forth in  claim 1 , wherein the controller calculates the unbalance value of the laundry and the variation of the unbalance value using a speed ripple extracted from the motor speed signal.  
   
   
       3 . The washing machine as set forth in  claim 2 , wherein the controller calculates the unbalance value of the laundry and the variation of the unbalance value by detecting the speed ripple in real time.  
   
   
       4 . The washing machine as set forth in  claim 2 , wherein the controller calculates the unbalance value of the laundry and the variation of the unbalance value using the speed ripple extracted from the motor speed signal during a change of the speed of the washing motor.  
   
   
       5 . The washing machine as set forth in  claim 1 , wherein the controller comprises a motor speed signal processing unit detecting a speed ripple from the motor speed signal and calculating an absolute value of the detected speed ripple, and calculates the unbalance value and the variation of the unbalance value using the absolute value of the speed ripple.  
   
   
       6 . The washing machine as set forth in  claim 5 , wherein the controller further comprises an unbalance value detecting unit calculating the unbalance value using the absolute value of the speed ripple.  
   
   
       7 . The washing machine as set forth in  claim 6 , wherein the unbalance value detecting unit is a low-pass filter (LPF).  
   
   
       8 . The washing machine as set forth in  claim 1 , wherein the controller determines the unbalanced state of the laundry in the rotary tub by respectively comparing the unbalance value and the variation of the unbalance value to predetermined first reference values and by comparing another unbalance value of laundry, obtained by increasing the rpm of the washing motor, to a predetermined second reference value.  
   
   
       9 . The washing machine as set forth in  claim 8 , wherein the unbalance state of the laundry is determined by comparing a conical unbalance value to the predetermined first and second reference values.  
   
   
       10 . A method for detecting an unbalanced state of laundry in a washing machine, having a rotary tub containing the laundry and a washing motor for rotating the rotary tub, the method comprising: 
 detecting a rotating speed of the washing motor and outputting a motor speed signal;    calculating an unbalance value of the laundry contained in the rotary tub and a variation of the unbalance value using the outputted motor speed signal; and    determining an unbalanced state of the laundry by comparing the unbalance value and the variation of the unbalance value to respective reference values.    
   
   
       11 . The method as set forth in  claim 10 , wherein calculating the unbalance value of the laundry and the variation of the unbalance value comprises: 
 extracting a speed ripple from the outputted motor speed signal; and    calculating the unbalance value and the variation of the unbalance value using the extracted speed ripple.    
   
   
       12 . The method as set forth in  claim 11 , wherein the unbalance value of the laundry and the variation of the unbalance value are calculated in real time using the speed ripple extracted in real time.  
   
   
       13 . The method as set forth in  claim 11 , wherein the unbalance value of the laundry and the variation of the unbalance value are calculated using the speed ripple extracted during the changing of the speed of the washing motor.  
   
   
       14 . The method as set forth in  claim 11 , wherein the calculation of the unbalance value of the laundry and the variation of the unbalance value further comprises calculating an absolute value of the extracted speed ripple, and the unbalance value of the laundry and the variation of the unbalance value are calculated using the absolute value.  
   
   
       15 . The method as set forth in  claim 10 , wherein determining the unbalanced state of the laundry comprises: 
 respectively comparing the unbalance value and the variation of the unbalance value to predetermined first reference values;    increasing the rpm of the washing motor; and    comparing a newly obtained unbalance value to a predetermined second reference value.    
   
   
       16 . The method as set forth in  claim 15 , wherein the unbalanced state of the laundry is determined by comparing a conical unbalance value to the predetermined first and second reference values.