Patent Abstract:
A disinfecting washing machine includes a disinfecting liquid dispenser, a drive unit and a control unit. The disinfecting liquid dispenser supplies a disinfecting liquid to disinfect laundry. The drive unit outputs first and second voltages to determine a concentration of the disinfecting liquid. The control unit detects the concentration of the disinfecting liquid and controlling the drive unit so that the disinfecting liquid has a concentration within a preset range.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application claims the benefit of Korean Application No. 2002-46778, filed Aug. 8, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to a washing machine, and more particularly, to a disinfecting washing machine equipped with a disinfecting liquid dispenser.  
           [0004]    2. Description of the Related Art  
           [0005]    Colloidal silver can be produced by forming silver ions (Ag + ) and dissolving them in water. The colloidal silver is used as an antibacterial agent or a bactericide. It is reported that the colloidal silver eliminates about 650 different kinds of bacteria. In particular, the colloidal silver is characterized as not inducing resistance, which is different from general antibiotics, and is safe because the colloidal silver has no toxic effects. Methods of manufacturing the colloidal silver are an electrolysis method, a chemical resolution method and a pulverization method.  
           [0006]    A disinfecting washing machine is a washing machine that is equipped with a disinfecting liquid dispenser that produces and supplies a colloidal silver to disinfect laundry through antibacterial and bactericidal actions of the colloidal silver.  
           [0007]    A conventional disinfecting washing machine is described below with reference to FIGS. 1 and 2.  
           [0008]    [0008]FIG. 1 is a cross section of a conventional disinfecting washing machine. As shown in FIG. 1, a water tub  104  is disposed in a body casing  102  to contain washing water. A washing tub  106  is disposed in the water tub  104 . A pulsator  108  is mounted in a lower portion of an interior of the washing tub  106  to be rotated in forward and reverse directions so as to form currents of the washing water. A drive unit  110  is positioned under the water tub  104  to rotate the washing tub  106  and the pulsator  108 . The drive unit  110  comprises a drive motor  112  and a power transmission unit  114 . The drive motor  112  is rotated by power supplied thereto, and the power transmission device  114  serves to selectively transmit power generated by the drive motor to the pulsator  108  and the washing tub  106 . A belt  116  is wound around the drive motor  112  and the power transmission device  114  to mediate transmission of the power. A drain assembly  118  comprises a pipe  118   a  to drain the washing water from the washing tub  106  and a drain pipe valve  118   b , which selectively opens and closes the drain pipe  118   a  to allow draining of the washing water from the washing tub  106 .  
           [0009]    [0009]FIG. 2 is a partially sectional view of a conventional disinfecting liquid dispenser. As depicted in FIG. 2, when power is supplied to the washing machine and a washing course is selected while laundry is contained in a disinfecting washing machine, washing water is fed into an interior of a water tub  104 . The washing water fed into the water tub  104  dissolves a detergent while passing through a detergent dispenser (not shown), and is supplied to the water tub  104  along with the dissolved detergent.  
           [0010]    If a user selects a disinfection washing course, an inlet valve  204  of a disinfecting liquid dispenser  120 , connected to external source of water through an inlet pipe  212 , is opened and the water is supplied to an interior of a storage container  122 , whereas the washing water is fed to the water tub  104 . When power is applied to two silver plates  220  and  222  of the disinfecting liquid dispenser  120 , a silver disinfecting liquid is produced. The silver disinfecting liquid is supplied to the interior of the washing tub  106  and disinfects the laundry.  
           [0011]    The water supplied though an inlet  202  of the storage container  122  is halted to stabilize a speed and a current of the water while filling a first space  210  of the storage container  122 . The water contained in the first space  210  overflows a first partition  206  and flows into a second space  214 . The water having passed through the first space  210  and flowing into the second space  214  fills the second space  214  to a water level corresponding to the height of a second partition  208 . After the second space  214  is filled with the water, the water overflows the second partition  208  and flows into a third space  224  and then is supplied to the interior of the washing tub  106  through an outlet pipe  124  from an outlet  216  of the storage container  122 . The water flows into the third space  224  while a certain amount of the water is contained in the second space  214 . In a process, the silver disinfecting liquid is produced through electrolysis in the water, and the produced disinfecting liquid is supplied to the washing tub  106  through the outlet  216 . The process of producing a disinfecting liquid is continuously carried out while the water is supplied to the storage container  122 . A top  218  of the storage container  122  fixedly holds the sliver plates  220  and  222  in the water contained in the second space  214 . The storage container  122 , the top  218 , the inlet  202 , the outlet  216  and the bypass pipe  128  may be of a nonconductive material.  
           [0012]    Further, in the process of producing the disinfecting liquid, if the amount of the water supplied through the inlet  202  is large, the water contained in the interior of the storage container  122  flows into a drain pipe  118 a through a bypass pipe  128  from a bypass outlet  126  at an upper portion of the storage container  122 , so the water can be maintained at an appropriate water level in the storage container  122 , thereby enabling a disinfecting liquid of a certain concentration to be produced. When the process of producing a disinfecting liquid is stopped, the water supply to the storage container  122  is stopped by closing of the inlet value  204  and the power to the silver plates  220  and  222  is stopped. At that time, the water remaining in the interior of the storage container  122  flows into the outlet  216  through remaining water discharging holes  206   a  and  208   a  and is completely discharged from the storage container  122 .  
           [0013]    After the washing water including the disinfecting liquid fills the washing tub  106 , washing of the laundry is performed by a rotation of the pulsator  108  and bacteria are killed by the disinfecting liquid in a process of the washing of the laundry.  
           [0014]    The disinfecting liquid dispenser  120  carries out the electrolysis in the water by alternately applying a positive voltage and a negative voltage to the two silver plates  220  and  222 , respectively, thus generating the silver ions. The amount of the silver ions, which is a concentration of the colloidal silver, is proportional to an amount of current flowing through the two silver plates  220  and  222  or an amount of voltage applied to the two silver plates  220  and  222 .  
           [0015]    The disinfecting performance obtained by the colloidal silver is determined by the concentration of the colloidal silver. If the concentration of the colloidal silver is excessively low, a disinfecting performance of the colloidal silver decreases; but if the concentration of the colloidal silver is excessively high, the colloidal silver discolors the laundry. Accordingly, the concentration of the colloidal silver has to be appropriately adjusted so as not to damage the laundry while disinfecting the laundry. To produce the appropriate concentration of the colloidal silver, the amount of voltage applied to the two silver plates  220  and  222  or the amount of current flowing through the two silver plates  220  and  222  has to be appropriately adjusted.  
           [0016]    Since the concentration of the colloidal silver is varied according to a pressure and temperature of the water, the voltage applied to the two silver plates  220  and  222  or the current flowing through the two silver plates  220  and  222  must not be limited to a fixed value but must be varied in a certain range so as to maintain the concentration of colloidal silver in an appropriate range.  
         SUMMARY OF THE INVENTION  
         [0017]    Accordingly, an aspect of the present invention is to provide a disinfecting washing machine, which is capable of controlling an amount of voltage applied to silver plates using a pulse width modulation signal, so a colloidal silver can have a concentration in an appropriate range that sufficiently disinfects laundry but does not damage the laundry.  
           [0018]    Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
           [0019]    To accomplish the above and/or other aspects, a disinfecting washing machine comprises a disinfecting liquid dispenser supplying a disinfecting liquid to disinfect laundry; a drive unit outputting first and second voltages to determine a concentration of the disinfecting liquid; and a control unit detecting the concentration of the disinfecting liquid and controlling the drive unit so that the concentration of the disinfecting liquid is within a preset range. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    These and other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:  
         [0021]    [0021]FIG. 1 is a cross section of a conventional disinfecting washing machine;  
         [0022]    [0022]FIG. 2 is a partially sectional view showing a disinfecting liquid dispenser of FIG. 1;  
         [0023]    [0023]FIG. 3 is a block diagram showing a device for controlling a concentration of colloidal silver used in a washing machine of an embodiment of the present invention;  
         [0024]    [0024]FIG. 4 is a circuit diagram of a drive unit of the colloidal silver concentration control device of the embodiment of the present invention; and  
         [0025]    FIGS.  5 A- 5 E are charts showing waveforms of signals applied to the drive unit of FIG. 4. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
         [0027]    A disinfecting washing machine and method of controlling the disinfecting washing machine are described with reference to FIGS. 3, 4 and  5 A- 5 E. FIG. 3 is a block diagram showing a device for controlling the concentration of colloidal silver used in a washing machine of an embodiment of the present invention. As shown in FIG. 3, a drive unit  302  alternately applies positive and negative voltages to a disinfecting liquid dispenser  304  to produce colloidal silver. Levels and polarities of the voltages applied to the disinfecting liquid dispenser  304  from the drive unit  302  are controlled by a duty ratio of a pulse width modulation signal  314 , a first switching signal  316  and a second switching signal  318  outputted from a control unit  306  to the drive unit  302 .  
         [0028]    An amount of current supplied to the disinfecting liquid dispenser  304  is proportional to amounts of voltages applied to the disinfecting liquid dispenser  304 . The amount of current, supplied to the disinfecting liquid dispenser  304 , is detected by a current detection unit  308  and a current/voltage conversion unit  310 . The control unit  306  determines the duty ratio of the pulse width modulation signal  314  in consideration of the amount of the current being currently supplied to the disinfecting liquid dispenser  304 . If the amount of current being currently supplied to the disinfecting liquid dispenser  304  deviates from an appropriate range that can produce the colloidal silver of an appropriate concentration necessary for a disinfection of laundry, the amount of current supplied to the disinfecting liquid dispenser  304  is controlled to be in the appropriate range by increasing or decreasing a pulse width of the pulse width modulation signal  314 .  
         [0029]    If excessive amounts of voltages are supplied to the disinfecting liquid dispenser  304 , a concentration of the colloidal silver is increased, thus damaging the laundry. A current limiter  312  generates an excessive current signal  320  and inputs the excessive current signal  320  to the control unit  306  when the amount of current detected by the current detection unit  308  exceeds a preset reference value. When the excessive current signal  320  is generated, the control unit  306  decreases the concentration of the colloidal silver by lowering a level of voltage applied to the disinfecting liquid dispenser  304  by decreasing the duty ratio of the pulse width modulation signal  314  to the drive unit  302 , or by completely shutting off a power supply to the disinfecting liquid dispenser  304 .  
         [0030]    A construction of the drive unit  304  controlling the concentration of the colloidal silver is described in detail below with reference to FIGS. 4 and 5A- 5 E. FIG. 4 is a circuit diagram showing the drive unit of the colloidal silver concentration control unit. As shown in FIG. 4, a PNP bipolar transistor  402  and an NPN bipolar transistor  404  form a first series circuit between a voltage VCC and a second voltage GND. A PNP bipolar transistor  406  and a NPN bipolar transistor  408  form a second series circuit in parallel with the first series circuit.  
         [0031]    First and second NPN bipolar transistors  410  and  412  are connected in series to each other between a base of the PNP bipolar transistor  402  of the first series circuit and the second voltage GND. The first NPN bipolar transistor  410  is controlled by the pulse width modulation signal  314 , while the second NPN bipolar transistor  412  is controlled by the first switching signal  316 . Accordingly, when the pulse width modulation signal  314  and the first switching signal  316  are both at a high level, the first and second NPN bipolar transistors  410  and  412  are both turned on. When the first and second NPN bipolar transistors  410  and  412  are both turned on, the PNP bipolar transistor  402  of the first series circuit is turned on. As a result, while the second NPN bipolar transistor  412  is turned on, the duty ratio of the pulse width modulation signal  314  determines a turned-on range of the PNP bipolar transistor  402  of the first series circuit. The NPN bipolar transistor  404  of the first series circuit is controlled by the second switching signal  318 . A first control voltage  326  outputted from between the PNP bipolar transistor  402  and the NPN bipolar transistor  404  of the first series circuit is applied to one of the two silver plates  220  or  222  of the disinfecting liquid dispenser  304 .  
         [0032]    Third and fourth NPN bipolar transistors  414  and  416  are connected in series to each other between a base of the PNP bipolar transistor  406  of the second series circuit and the second voltage GND. The third NPN bipolar transistor  414  is controlled by the pulse width modulation signal  314 , while the fourth NPN bipolar transistor  416  is controlled by the second switching signal  318 . Accordingly, when the pulse width modulation signal  314  and the second switching signal  318  are both at a high voltage level, the third and fourth NPN bipolar transistors  414  and  416  are both turned on. When the third and fourth NPN bipolar transistors  414  and  416  are both turned on, the PNP bipolar transistor  406  of the second series circuit is turned on. As a result, while the fourth NPN bipolar transistor  416  is turned on, the duty ratio of the pulse width modulation signal  314  determines a turned-on range of the PNP bipolar transistor  406  of the second series circuit. The NPN bipolar transistor  408  of the second series circuit is controlled by the first switching signal  316 . A second control voltage  328  outputted from between the PNP bipolar transistor  406  and the NPN bipolar transistor  408  of the second series circuit is applied to a remaining one of the two silver plates  220  or  222  of the disinfecting liquid dispenser  304 . In FIG. 4, an emitter current of the NPN bipolar transistors  404  and  416  is detected by the current detection unit  308 , as shown in FIG. 3, and converted into a voltage signal in the current/voltage conversion unit  310 . The control unit  306  determines an amount of current being currently supplied to the disinfecting liquid dispenser  304  based on a magnitude of the converted voltage signal.  
         [0033]    FIGS.  5 A- 5 E are charts showing waveforms of signals applied to the drive unit of FIG. 4.  
         [0034]    As shown in FIGS.  5 A- 5 B, the first and second switching signals  316  and  318 , which are input signals, have opposite phases, respectively. A slight dead time t d  exists between transition points of the first and second switching signals  316  and  318 . If the first and second switching signals  316  and  318  transition at a same time, an overlapped range is formed. In this case, the two silver plates  220  and  222  of the disinfecting liquid dispenser  304  are short-circuited. When the dead time t d  is provided between the first and second signals  316  and  318 , the two silver plates  220  and  222  of the disinfecting liquid dispenser  304  can be prevented from short-circuiting. As shown in FIG. 5C, the pulse width modulation signal  314 , which is another input signal, is a signal whose duty ratio is variable by the control unit  306 . The duty ratio of the pulse width modulation signal  314 , as shown in FIG. 5C, is 100%.  
         [0035]    As shown in FIGS.  5 D- 5 E, the first and second control voltages  326  and  328 , which are output signals, have opposite phases. A phase of the first control voltage  326  is a same phase as that of the first switching signal  316 , while a phase of the second control voltage  328  is a same phase as that of the second switching signal  318 . Levels of the first and second control voltages  326  and  328  are proportional to the duty ratio of the pulse width modulation signal  318 . In FIG. 5D- 5 E, the levels “A” of the first and second control voltages  326  and  328  are for the case where the duty ratio of the pulse width modulation signal  314  is 100%, the levels “B” of the first and second control voltages  326  and  328  are for the case where the duty ratio of the pulse width modulation signal  314  is about  90 %, and the levels “C” of the first and second control voltages  326  and  328  are for the case where the duty ratio of the pulse width modulation signal  314  is about 50%.  
         [0036]    An operation of the drive unit  302 , which controls the colloidal silver concentration, of the disinfecting liquid dispenser  304  is described with reference to FIGS. 4 and 5A- 5 E. If the first switching signal  316  of the input signals  314 ,  316  and  318 , as shown in FIGS.  5 A- 5 C, respectively, is at a high voltage level and the second switching signal  318  is at a low voltage level, the first switching signal  316  is a high voltage level, so the second NPN bipolar transistor  412  is turned on. In this state, since the first NPN bipolar transistor  410  is only turned on when the pulse width modulation signal  314  is in a high voltage level range, the PNP bipolar transistor  402  of the first series circuit has a turned-on range which is equal to the high voltage level range of the pulse width modulation signal  314 . At this time, the second switching signal  318  is at the low voltage level, so the NPN bipolar transistor  404  of the first series circuit is turned off.  
         [0037]    In contrast, the fourth NPN bipolar transistor  416  is turned off by the second switching signal  318  of the low voltage level. Accordingly, turned-on and turned-off operations of the third NPN bipolar transistor  414  in response to the pulse width modulation signal  314  do not affect operation of the PNP bipolar transistor  406  of the second series circuit. At this time, the first switching signal  316  is at the high voltage level, so the NPN bipolar transistor  408  of the second series circuit is turned on.  
         [0038]    As described above, in a range where the first switching signal  316  is at the high voltage level and the second switching signal  318  is at the low voltage level, only the PNP bipolar transistor  402  of the first series circuit and the NPN bipolar transistor  408  of the second series circuit are turned on, so that a source voltage VCC, the PNP bipolar transistor  402  of the first series circuit, the disinfecting liquid dispenser  304 , the NPN bipolar transistor  408  of the second series circuit and the second voltage GND provide a closed circuit to enable current to flow through the two silver plates  220  and  222 . In this case, the first control voltage  326  has a positive polarity, while the second control voltage  328  has a negative polarity. Since a turned-on range of the PNP bipolar transistor  402  of the first series circuit is proportional to the duty ratio of the pulse width modulation signal  314 , the levels of the first and second control voltages  326  and  328  are proportional to the duty ratio of the pulse width modulation signal  314 .  
         [0039]    If the first switching signal  316  is at the low voltage level and the second switching signal  318  is at the high voltage level as a result of alternating the voltage levels of the first and second switching signals  316  and  318 , the second switching signal is at the high voltage level, so the fourth NPN bipolar transistor  416  is turned on. In this state, the third NPN bipolar transistor  414  is only turned on when the pulse width modulation signal  314  is in the high voltage level range, so that the PNP bipolar transistor  406  of the second series circuit has a turned-on range which is equal to the high voltage level range of the pulse width modulation signal  314 . At this time, the first switching signal  316  is at the low voltage level, so that the NPN bipolar transistor  408  of the second series circuit is turned off.  
         [0040]    In contrast, the second NPN bipolar transistor  412  is turned off by the first switching signal  316  of the low voltage level. Accordingly, turned-on and turned-off operations of the first NPN bipolar transistor  410  in response to the pulse width modulation signal  314  do not affect operation of the PNP bipolar transistor  402  of the first series circuit. At this time, the second switching signal  316  is at the high voltage level, so that the NPN bipolar transistor  404  of the first series circuit is turned on.  
         [0041]    As described above, in a range where the second switching signal  318  is at the high voltage level and the first switching signal  316  is at the low voltage level, only the PNP bipolar transistor  406  of the second series circuit and the NPN bipolar transistor  404  of the first series circuit are turned on, so the source voltage VCC, the PNP bipolar transistor  406  of the second series circuit, the disinfecting liquid dispenser  304 , the NPN bipolar transistor  404  of the first series circuit and the second voltage GND provide a closed circuit and enable current to flow through the two silver plates  220  and  222 . In this case, the first control voltage  326  has the negative polarity, while the second control voltage  328  has the positive polarity. Since the turned-on range of the PNP bipolar transistor  406  of the second series circuit is proportional to the duty ratio of the pulse width modulation signal  314 , the levels of the first and second control voltages  326  and  328  are proportional to the duty ratio of the pulse width modulation signal  314 .  
         [0042]    As described above, the polarities of the first and second control voltages  326  and  328  outputted from the drive unit  302  to the disinfecting liquid dispenser  304  are repeatedly alternated by the first and second switching signals  316  and  318 . The amounts of the first and second control voltages  326  and  328  are controlled to be proportional to the duty ratio of the pulse width modulation signal  314 . Since the first and second control voltages  316  and  318  are voltages applied to the two silver plates  220  and  222 , the colloidal silver of a concentration proportional to the levels of the first and second control voltages  326  and  328  is produced. The control unit  306  determines whether the concentration of a currently produced colloidal silver is within an appropriate range by monitoring an amount of current flowing through the two silver plates  220  and  222 . If the concentration of the colloidal silver deviates from the appropriate range, the control unit  306  adjusts the amounts of the first and second control voltages  326  and  328  applied to the disinfecting liquid dispenser  304  by varying the duty ratio of the pulse width modulation signal  314 . Since the polarities of the first and second control voltages  326  and  328  are repeatedly alternated, an oxidation and a reduction of silver ions are uniformly carried out on the two silver plates  220  and  222 , thus preventing only one of the two silver plates  220  and  222  from being consumed.  
         [0043]    As described above, a disinfecting washing machine is provided, which is capable of maintaining a concentration of a colloidal silver within an appropriate range, which does not damage laundry while sufficiently disinfecting the laundry, by controlling amounts of voltages applied to silver plates based on a preset concentration of the colloidal silver using a duty ratio of a pulse width modulation signal. Further, the disinfecting washing machine prevents only one of the two silver plates from being consumed by repeatedly alternating polarities of first and second control voltages  326  and  328 .  
         [0044]    Although a few preferred embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Technology Classification (CPC): 3