Patent Abstract:
The present invention provides a method of controlling opening and closing of a door in a drum-type washing machine. When the drum-type washing machine suddenly stops in operation, e.g. in case of a mistake by a user or a switch-off, a water level of a tub is sensed, which shows lower than predetermined height, thereafter a door-lock-system is converted that the door can be opened. To this function, the present invention has an effect on protecting against an outflow of water of the tub in case the user wrongly opens the door.

Full Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a method of controlling opening and closing of a door in a drum-type washing machine, to put it concretely, that opening and closing of the door in the drum-type washing machine is controlled depending on a water level of a tub when the drum-type washing machine comes to a stop in operation.  
         [0003]     2. Description of the Related Art  
         [0004]     A washing machine is to decontaminate dirt on clothes or bedding through washing, rinsing and dehydrating.  
         [0005]     A drum-type washing machine has a door in front to put laundry in it. A cabinet in the drum-type washing machine has a door-lock-switch which prevents the door from opening while the drum-type washing machine is on.  
         [0006]     The door-lock-switch is affected by a controller of the drum-type washing machine. When the drum-type washing machine is operating, the controller makes the door unopened. When the drum-type washing machine finishes operating, the controller makes it possible to open the door.  
         [0007]     However, when the drum-type washing machine stops by a pause, a mistake by a user, a switch-off, the drum-type washing machine up to the present releases the door-lock-switch and the door can be opened even though water is contained in a tub.  
         [0008]     Consequently, the conventional drum-type washing machine causes inconvenience that water of the tub flows out of the drum-type washing machine as the user opens the door.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention is designed to cope with the above-mentioned problem, its main purpose places in providing a method of controlling opening and closing a door in a drum-type washing machine, which prevents water from running out of the machine which unexpectedly becomes stopped while its operation. It is feasible that a water level of a tub is considered before deciding whether to allow the door to open or not.  
         [0010]     The method of controlling opening and closing of the door in the drum-type washing machine comprises the steps of: operating the drum-type washing machine; locking the door not to open; sensing the water level of the tub when the drum-type washing machine stops operating; and releasing a door-lock so that the door becomes ready to open if the water level of the tub is sensed lower than predetermined height.  
         [0011]     When the door-lock is released, a door-opening-lamp is turned on while a door-closing-lamp is turned off.  
         [0012]     If the water level of the tub is sensed higher than predetermined height, the door-lock is maintained and it is returned to the step of sensing the water level of the tub.  
         [0013]     The method of controlling opening and closing of the door in the drum-type washing machine further comprises that a child-lock is turned on before the drum-type washing machine stops. The child-lock is on by a user or automatically after the drum-type washing machine is operating.  
         [0014]     The method of controlling opening and closing of the door in the drum-type washing machine further comprises that the door-lock is released following by turning off the child-lock if the drum-type washing machine stops operating and the water level in the drum-type washing machine is lower than predetermined height. The child-lock becomes off by the user or automatically.  
         [0015]     Therefore, the method of controlling opening and closing of the door in the drum-type washing machine prevents water from flowing out of the door when the drum-type washing machine which has been operating stops or pauses. The reason is that the door holds its condition as can-be-opened or should-be-locked, reading the water level of the tub. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:  
         [0017]      FIG. 1  is an illustration of a drum-type washing machine adapted for the present invention.  
         [0018]      FIG. 2  is a flow chart of a method of controlling opening and closing of a door in the drum-type washing machine in accordance with the 1st embodiment of the present invention.  
         [0019]      FIG. 3  is the flow chart of the method of controlling opening and closing of the door in the drum-type washing machine in accordance with the 2nd embodiment of the present invention.  
         [0020]      FIG. 4  is the flow chart of the method of controlling opening and closing of the door in the drum-type washing machine in accordance with the 3rd embodiment of the present invention.  
         [0021]      FIG. 5  is the flow chart of the method of controlling opening and closing of the door in the drum-type washing machine in accordance with the 4th embodiment of the present invention.  
         [0022]      FIG. 6  is the flow chart of the method of controlling opening and closing of the door in the drum-type washing machine in accordance with the 5th embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]     Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.  
         [0024]     Now, preferred embodiment of the present invention will be hereinafter described in detail with reference to the accompanying drawings.  
         [0025]      FIG. 1  is an illustration of a drum-type washing machine adapted for the present invention.  
         [0026]     As seen in  FIG. 1 , the drum-type washing machine includes: a door  1 ; a cabinet assembly  2  that shapes a body of the drum-type washing machine; a tub (not shown) in the cabinet assembly  2  that contains water; a drum  3  that rotates inside of the tub; and a motor (not shown) connected to the drum  3  that makes the drum  3  rotate.  
         [0027]     A detergent box  4  with cleaning or softening materials and a control panel unit  5  with a controller of the drum-type washing machine are installed in the cabinet assembly  2 .  
         [0028]     A cabinet cover  6  which is the front of the cabinet assembly  2  has a hole  7  for holding the door  1 . One side of the door  1  is connected to the cabinet cover  6  with a hinge and the other side of the door  1  hangs a hook  8 .  
         [0029]     The hook  8  fixes the door  1  by meeting a latch assembly  9  in the cabinet cover  6 .  
         [0030]     The latch assembly  9  is regulated by the controller in the control panel unit  5 . The controller impresses or interrupts an electric current to a door-lock-switch (not shown) and commands its function. The latch assembly  9  accordingly runs and controls opening and closing of the door.  
         [0031]     A child-lock-button  10  is on the control panel unit  5 . As a user pushes the child-lock-button  10 , a signal is delivered to the controller. After receiving the signal, the controller orders the latch assembly  9  to work and the door  1  is laid in a locking condition.  
         [0032]     A child-lock is required to keep a child from entering the drum  3  after opening the door  1 .  
         [0033]     The control panel unit  5  has a door-opening-lamp  11  and a door-closing-lamp  12 , which inform the user whether the door  1  can be opened or not.  
         [0034]     Referring to  FIG. 2 , a method of controlling opening and closing of the door in the drum-type washing machine according to the 1st embodiment comprises the steps of: operating the drum-type washing machine at step S 10  with manipulation by the user after laundry is loaded in the drum  3 ; locking the door  1  at step S 20  by impressing the electric current to the door-lock-switch before or after or simultaneously with step S 10  and by working the latch assembly  9 ; sensing whether the drum-type washing machine stops in operation at step S 30 ; sensing the water level of the tub at step S 40  when the drum-type washing machine stops operating; and releasing the door-lock at step S 50  so that the door  1  becomes ready to open by the latch assembly  9  if the water level of the tub is sensed lower than predetermined height.  
         [0035]     The step S 20  of locking the door impresses the electric current to the door-lock-switch and converts the door into locking. In addition, it turns on the door-closing-lamp  12 .  
         [0036]     The step S 30  of sensing the stop implies both the cases that the user puts a stop to the operation of the drum-type washing machine and the drum-type washing machine unexpectedly stops without manipulation by the user.  
         [0037]     The former is, for example, the user turns off a power to put more laundry into the drum  3  before water is drained. The latter is that the drum-type washing machine becomes stopped due to a cut-off of the power, a mistake by the user or the incapacity of motor.  
         [0038]     The step of S 40  sensing the water level reads the water level contained in the tub and decides whether the door-lock is released.  
         [0039]     The step of S 50  releasing the door-lock interrupts the electric current to the door-lock-switch and makes the latch assembly  9  remove the door-lock when the water level of the tub is lower than predetermined height.  
         [0040]     As the controller turns on the door-opening-lamp  11  and turns off the door-closing-lamp  12  at a time, the user can notice the door  1  is available to open at step S 50 .  
         [0041]     The drum-type washing machine is turned out to be in normal operation at step S 30 , it is returned to step S 10  and continues operating.  
         [0042]     If the water level of the tub is higher than predetermined height at step S 40 , the door is locked as it used to be. It is returned to step S 40  and waits till the water level of the tub gets lowered.  
         [0043]     As soon as the water level of the tub is under predetermined height, the step S 50  is activated and the door-lock is released.  
         [0044]      FIG. 3  is the flow chart of the method of controlling opening and closing of the door in the drum-type washing machine in accordance with the 2nd embodiment of the present invention. The 2nd embodiment is developed from the 1st one by adding a function of the child-lock.  
         [0045]     The method of controlling opening and closing of the door in the drum-type washing machine according to 2nd embodiment comprises the steps of: operating the drum-type washing machine at step S 110  after the child-lock-button  10  is on and the child-lock is set up at step S 101 ; locking the door at step S 120 ; sensing whether the drum-type washing machine stops in operation at step S 130 ; sensing the water level of the tub at step S 140  when the drum-type washing machine stops operating; checking the child-lock to be released by manipulation of the child-lock-button at step S 150  when the water level of the tub is lower than predetermined height; releasing the door-lock to be opened at step S 160  when the child-lock-button is released; and turning off the door-closing-lamp and turning on the door-opening-lamp at step S 161  after the door-lock comes to released.  
         [0046]     As the user puts into operation of the child-lock, the door has been already locked at step S 110 . In addition to that, the door is automatically locked depending on the operation of the drum-type washing machine, a double-lock-system is executed at step S 120 .  
         [0047]     Since the child-lock has priority over any other control, the door maintains the locking condition in any cases if the child-lock is on, regardless of the door-lock-switch-off.  
         [0048]     The latch assembly functions the child-lock by the controller in the embodiment, though the latch assembly and a separate locking device can be installed in the drum-type washing machine in order to implement the child-lock.  
         [0049]     Releasing the child-lock by the user is confirmed at step S 150 . Only if the child-lock-releasing-signal is received through the child-lock-button, the door becomes ready to open at step S 160 . If not, it waits till the signal is received.  
         [0050]     If the water level of the tub is higher than predetermined height at step S 140 , the door  1  is locked as it used to be. It is returned to step S 140  and waits till the water level of the tub is lowered at step S 142 .  
         [0051]      FIG. 4  is the flow chart of the method of controlling opening and closing of the door in the drum-type washing machine in accordance with the 3rd embodiment of the present invention.  
         [0052]     From steps S 101  to S 140  in the 3rd embodiment is the same as the process in the 2nd one. When the water level of the tub is lower than predetermined height at step S 140 , contrary to the 2nd embodiment, the child-lock is automatically turned off at step S 200  and allows the door to open by releasing the door-lock at step S 201 . It is possible even though there is no child-lock-releasing-signal.  
         [0053]     When the door-lock is released at step S 201 , the door-closing-lamp is turned off and the door-opening-lamp is turned on.  
         [0054]     The further explanation is excluded since the rests are identical with the  2 nd embodiment.  
         [0055]      FIG. 5  is the flow chart of the method of controlling opening and closing of the door in the drum-type washing machine in accordance with the 4th embodiment of the present invention.  
         [0056]     The 4th embodiment includes, contrary to the 2nd one, the child-lock is off before the drum-type washing machine is in operation at step S 300  and the child-lock is on after its operation at step S 301 .  
         [0057]     The method of controlling opening and closing the door in the drum-type washing machine according to the 3rd embodiment comprises the steps of: operating the drum-type washing machine at step S 110  while the child-lock-button is off at step S 300 ; locking the door and turning on the door-closing-lamp at step S 120 ; automatically turning on the child-lock at step S 301 ; sensing whether the drum-type washing machine stops in operation at step S 130 ; sensing the water level of the tub at step S 140  when the drum-type washing machine stops operating; checking the child-lock to be released by manipulation of the child-lock-button at step S 150  when the water level of the tub is lower than predetermined height; releasing the door-lock to be opened at step  160  when the child-lock is released; and turning off the door-closing-lamp and turning on the door-opening-lamp at step S 161  after the door-lock comes to released.  
         [0058]     The further explanation is excluded since the rests are identical with the 2nd embodiment.  
         [0059]      FIG. 6  is the flow chart of the method of controlling opening and closing of the door in the drum-type washing machine in accordance with the 5th embodiment of the present invention.  
         [0060]     The 5th embodiment is the same as the  4 th one except that the child-lock is automatically turned off without the child-lock-releasing-signal at step S 302  when the water level of the tub is under predetermined height.  
         [0061]     The further explanation is excluded since the rests are identical with the 4th embodiment.  
         [0062]     The method of controlling opening and closing of the door in the drum-type washing machine has the practical strength:  
         [0063]     When the drum-type washing machine becomes stopped without finishing washing, the water level of the tub is sensed. Then, the door is opened only if the water level of the tub is lower than predetermined height. It can be prevented that water flows out caused by accidentally opening the door.  
         [0064]     The user can clearly understand the condition of the drum-type washing machine since a lamp indicates that the door can be opened or should be locked depending on the water level of the tub.  
         [0065]     When the drum-type washing machine stops in operation with the child-lock-on, the door-lock is released after the child-lock is released, even though the water level of the tub is under predetermined height. It can be prevented that the child opens the door when the drum-type washing machine is not operating.  
         [0066]     It can be more definitely prevented that the door is accidentally opened with water contained in the drum-type washing machine on the ground that opening and closing of the door is decided by the double-lock-system including the child-lock.  
         [0067]     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Technology Classification (CPC): 3