Washing machine

Abstract

A washing machine is provided. The washing machine controls a dehydration rotation speed by detecting a phase difference between a ball balancer and the laundry. Further, the washing machine controls a dehydration rotation speed at a dehydration segment based on a dehydration rotation speed of a driving device. Thereby, the washing machine minimizes energy using in a dehydration process by accelerating the dehydration rotation speed at a point at which a phase difference between the ball balancer and the laundry is a maximum. Further, by accelerating the dehydration rotation speed at a point at which the phase difference is a maximum, a vibration of the washing machine is remarkably reduced.

1 . A washing machine comprising:
 a drum to receive laundry to be washed;   a driving device to deliver a rotational driving force to the drum;   a ball balancer coupled to the drum to rotate in the same direction as the drum to reduce eccentricity of the drum;   a phase difference detection device disposed at the driving device to detect a phase difference between the ball balancer and the laundry as the drum rotates; and   a controller to control a dehydration rotation speed of the drum to dehydrate the laundry based on a phase difference detected in the phase difference detection device.   
   
   
       2 . The washing machine of  claim 1 , wherein the controller controls the dehydration rotation speed that includes:
 a first dehydration rotation speed in which the driving device maintains a constant rotational speed to detect the phase difference; and   a second dehydration rotation speed in which the driving device increases the constant rotational speed to dehydrate the laundry if the phase difference detected in the first dehydration rotation speed is within a setting range.   
   
   
       3 . The washing machine of  claim 2 , wherein the setting range is a period in which the phase difference increases from a first phase difference, which is a minimum, to a second phase difference, which is a maximum. 
   
   
       4 . The washing machine of  claim 2 , wherein if the phase difference is within the setting range, increasing from a minimum phase difference to a maximum phase difference, the controller gradually accelerates the driving device from the second dehydration rotation speed to a third dehydration rotation speed. 
   
   
       5 . The washing machine of  claim 2 , wherein if the phase difference is within the setting range, increasing from a minimum phase difference to a maximum phase difference, the controller accelerates the driving device from the second dehydration rotation speed to a third dehydration rotation speed at a predetermined slope. 
   
   
       6 . The washing machine of  claim 1 , wherein if the phase difference is within a setting range as an average rotation speed is accelerated at a predetermined slope, the controller increases a dehydration rotation speed in order to reduce vibrations produced by the drum. 
   
   
       7 . The washing machine of  claim 6 , wherein the setting range is a period in which the phase difference increases from a first phase difference, which is a minimum, to a second phase difference, which is a maximum. 
   
   
       8 . A washing machine comprising:
 a drum to receive laundry to be washed;   a driving device to deliver a rotational driving force to the drum;   a ball balancer coupled to the drum to rotate in the same direction as the drum to reduce eccentricity of the drum;   a rotation speed detection device disposed at the driving device to detect a dehydration rotation speed of the driving device as the driving device rotates; and   a controller to control the dehydration rotation speed during a dehydration segment of the laundry based on the dehydration rotation speed.   
   
   
       9 . The washing machine of  claim 8 , wherein the dehydration segment comprises:
 a first dehydration segment during which the driving device constantly maintains the dehydration rotation speed at an average rotation speed, and the rotation speed detection device detects a change of the dehydration rotation speed, and determines if the dehydration rotation speed is within a setting range; and   a second dehydration segment, following the first dehydration segment once the dehydration rotation speed is determined to be within a setting range, where the driving device accelerates the dehydration rotation speed.   
   
   
       10 . The washing machine of  claim 9 , wherein the setting range is a period in which an instantaneous rotation speed of the dehydration rotation speed decreases from a first instantaneous rotation speed, which is a maximum, to a second instantaneous rotation speed, which is a minimum. 
   
   
       11 . The washing machine of  claim 8 , wherein if an instantaneous rotation speed of the dehydration rotation speed is within a setting range increasing from a first instantaneous rotation speed, which is a maximum, to a second instantaneous rotation speed, which is a minimum, the controller gradually accelerates the dehydration rotation speed of the driving device from a first dehydration rotation speed to a second dehydration rotation speed. 
   
   
       12 . The washing machine of  claim 8 , wherein if an instantaneous rotation speed of the dehydration rotation speed is within a setting range increasing from a first instantaneous rotation speed, which is a maximum, to a second instantaneous rotation speed, which is a minimum, the controller controls the driving device to accelerate the dehydration rotation speed from a first dehydration rotation speed to a second dehydration rotation speed at a predetermined slope. 
   
   
       13 . The washing machine of  claim 8 , wherein the controller controls the driving device to accelerate the dehydration rotation speed at a first predetermined slope, and if the dehydration rotation speed is less than an average of an instantaneous dehydration rotation speed, the controller increases the dehydration rotation speed of the driving device at a second predetermined slope in order to reduce a vibration of the drum. 
   
   
       14 . A washing machine comprising:
 a drum for washing the laundry;   a driving device for delivering a driving force to the drum;   a ball balancer coupled to the drum to reduce eccentricity of the drum; and   a controller for controlling a rotational position of the ball balancer such that a center of gravity of the ball bouncer is opposite the center of gravity of the laundry during a dehydration cycle.