Drum type washing machine and method of detecting laundry weight thereof

Abstract

A drum type washing machine and a method of detecting laundry weight thereof that is capable of calculating a ratio of input voltage applied to a motor through phase control until the motor reaches a determined number of rotations to accurately detect the weight of laundry or the amount of eccentricity of the laundry received in a drum connected to the motor. The drum type washing machine comprises a motor for rotating a drum, and a control unit for controlling the number of rotations of the motor depending upon a washing operation and calculating a ratio of input voltage applied to the motor, i.e., a modified voltage value, to determine the weight of laundry received in the drum. The weight of laundry received in the drum is accurately detected in steps, and therefore, water consumption is reduced, and a uniform washing operation is performed.

1 . A method of detecting laundry weight of a drum type washing machine, comprising the steps of: 
 calculating a ratio of input voltage applied to a motor through phase control, i.e., a modified voltage value, every control cycle; and    determining the weight of laundry based on the modified voltage value calculated when the motor is rotated at constant speed.    
   
   
       2 . A method of detecting laundry weight of a drum type washing machine, comprising: 
 a first step of applying phase-controlled input voltage to a motor;    a second step of calculating a ratio of voltage applied to the motor to one-cycle input voltage, i.e., a modified voltage value, every phase control cycle, and determining whether the number of rotations of the motor reaches a predetermined number of rotations; and    a third step of adding the modified voltage values calculated at the second step, when the number of rotations of the motor reaches the predetermined number of rotations, to determine the weight of laundry.    
   
   
       3 . The method as set forth in  claim 2 , wherein the third step comprises: 
 a modified voltage value adding step of adding the modified voltage values calculated every control cycle until the number of rotations of the motor reaches the predetermined number of rotations; and    a laundry weight detecting step of determining whether the laundry weight is high or low in steps based on the sum of the modified voltage values.    
   
   
       4 . The method as set forth in  claim 3 , wherein the laundry weight detecting step determines the laundry weight in four steps based on the sum of the modified voltage values.  
   
   
       5 . The method as set forth in  claim 1 , wherein the modified voltage value is a ratio of voltage applied to the motor through the phase control to one-cycle sinusoidal-wave input voltage.  
   
   
       6 . A method of detecting laundry weight of a drum type washing machine, comprising: 
 a first step of applying input voltage, phase of which is controlled by a triac, to a motor;    a second step of calculating a ratio of voltage applied to the motor to one-cycle input voltage, i.e., a modified voltage value, every phase control cycle, and determining whether the number of rotations of the motor reaches a predetermined number of rotations; and    a third step of calculating ripples in the number of rotations of the motor for a predetermined period of time, when the number of rotations of the motor reaches the predetermined number of rotations, and detecting the weight of laundry based on the sum of the modified voltage values calculated at the second step and the calculated ripples in the number of rotations of the motor.    
   
   
       7 . The method as set forth in  claim 6 , wherein the third step comprises: 
 a modified voltage value adding step of adding the modified voltage values calculated every control cycle until the number of rotations of the motor reaches the predetermined number of rotations;    a ripple calculating step of calculating ripples in the number of rotations of the motor while the motor is rotated at the constant speed at the predetermined number of rotations;    a ripple adding step of adding the calculated ripples in the number of rotations of the motor; and    a laundry weight detecting step of calculating the difference between the sum of the modified voltage values and the sum of the ripples in the number of rotations of the motor to determine whether the laundry weight is high or low in steps.    
   
   
       8 . The method as set forth in  claim 7 , wherein, after the ripple adding step is performed, the laundry weight detecting step calculates the difference between the sum of the modified voltage values and the sum of the ripples in the number of rotations of the motor to determine whether the laundry weight is high or low.  
   
   
       9 . The method as set forth in  claim 8 , wherein the laundry weight detecting step determines the weight of the laundry in four steps based on the sum of the modified voltage values.  
   
   
       10 . The method as set forth in  claim 6 , wherein the third step comprises: 
 determining the amount of eccentricity of the laundry based on the ripples in the number of rotations of the motor.    
   
   
       11 . The method as set forth in  claim 6 , wherein the modified voltage value is a ratio of voltage applied to the motor through the phase control to one-cycle sinusoidal-wave input voltage.  
   
   
       12 . A drum type washing machine comprising: 
 a motor for rotating a drum; and    a control unit for controlling the number of rotations of the motor depending upon a washing operation and calculating a ratio of input voltage applied to the motor, i.e., a modified voltage value, to determine the weight of laundry received in the drum.    
   
   
       13 . The machine as set forth in  claim 12 , further comprising: 
 a rotation number detecting sensor for sensing the number of rotations of the motor.    
   
   
       14 . The machine as set forth in  claim 12 , wherein the control unit comprises: 
 a drive control part for controlling phase of the input voltage applied to the motor to control the driven speed of the motor; and    a laundry weight calculating part for calculating the modified voltage value every phase control cycle of the drive control part and adding the respective modified voltage value calculated until the number of rotations of the motor reaches a predetermined number of rotations to determine the laundry weight in steps.    
   
   
       15 . The machine as set forth in  claim 14 , wherein the laundry weight calculating part calculates ripples in the number of rotations of the motor when the number of rotations of the motor reaches the predetermined number of rotations, and detects the weight of the laundry based on the sum of the modified voltage values and the calculated ripples in the number of rotations of the motor.  
   
   
       16 . The machine as set forth in  claim 15 , wherein the laundry weight calculating part determines the amount of eccentricity of the laundry in steps based on the size of the calculated ripples in the number of rotations of the motor.  
   
   
       17 . The machine as set forth in  claim 12 , wherein the modified voltage value is a ratio of voltage applied to the motor through the phase control to one-cycle sinusoidal-wave input voltage.  
   
   
       18 . The method as set forth in  claim 2 , wherein the modified voltage value is a ratio of voltage applied to the motor through the phase control to one-cycle sinusoidal-wave input voltage.