Abstract:
Toaster cum microwave oven having a heater for toasting bread, including a memory for storing a voltage level to a heater according to the function of the toaster the user selects, a temperature sensor for sensing an inside temperature of the toaster, and a microcomputer for controlling a toasting time period according to a kind and a toasting level of bread the user selects, and an inside temperature of the toaster, and controlling the microwave oven according to a command received through the first key input part, thereby permitting toasting bread to a desired degree of toasting regardless of the inside temperature and continued user of the toaster.

Description:
[0001]     This application claims the benefit of the Korean Application Nos. P2002-0052852 and P2002-0052853, two of which are filed on Sep. 3, 2002, which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to microwave ovens, and more particularly, a toaster cum microwave oven, and a method for operating the same.  
         [0004]     2. Background of the Related Art  
         [0005]     In general, the microwave oven heats a heating object with a microwave oven. As shown in  FIG. 1 , a related art microwave oven is provided with a heating chamber  2  in a cavity assembly  1  for heating the heating object placed therein by applying the microwave thereto, and a door  4  for opening/closing the heating chamber  2 .  
         [0006]     There is an outfit chamber  10  at a side of the heating chamber  4 , covered with an outer casing  6 . The outfit chamber  10  is provided with a magnetron  12  for generating a microwave, a high voltage transformer  14  for applying a high voltage, and a fan (not shown) for forming an air flow that cools the electric components and passes through the heating chamber  2 .  
         [0007]     However, though the related art microwave oven, having different functions, can cook different food, there is no microwave oven that can toast bread, yet.  
         [0008]     That is, because the related microwave oven having no heater can not toast bread at all, despite of the many functions of microwave oven, users can not but use separate toaster for simple toasting of bread, there are not only an expense for buying a toaster, but also inconvenience in use.  
         [0009]     Under the foregoing reasons, a toaster cum microwave oven has been developed, which has a system as illustrated in  FIG. 2 .  
         [0010]     Referring to  FIG. 2 , the related art toaster cum microwave oven is provided with a cavity assembly  20  having a cavity  22  formed therein, and an outfit chamber  23  at a side of the cavity  22 . In the cavity  22 , the object (food) is heated with a microwave. Different electronic components for generating the microwave oven are provided in the outfit chamber  23 . The microwave oven illustrated in  FIG. 2  is provided with a front plate  21 .  
         [0011]     There is a cavity door  24  for opening/closing the cavity  22 . When the cavity door  24  is closed, the cavity door  24  is brought into contact with the front plate  21  to enclose the cavity  22 . The cavity door  24  has a door handle  25  for the user to open/close the cavity door  24 .  
         [0012]     There is an outer case  27  covered on an upper part, sides of the cavity assembly  20  and the outfit chamber  23 . There is a toaster  30  in the outfit chamber  23  in front of electronic components for generating the microwave. The toaster  30  is mounted through an opening in the front plate  21 . There is a toaster panel  32  in front of the toaster  30 . An outside of the toaster panel  32  is formed of a material the same with the cavity door  24 . Therefore, the toaster panel  32  forms a smooth surface together with the cavity door  24 .  
         [0013]     The toaster  30  will be described in more detail. There are a plurality of fastening hooks (not shown) on a rear surface of the toaster panel  32 , a toaster door  40  hinged on the toaster panel  32 , and two trays  74  for supporting at least one sliced piece of bread.  
         [0014]     There is a control panel  26  in an upper part of front surface of the cavity door  24 , provided with a first selection part  26   a  for selecting functions of the microwave oven, and a second selection part  26   b  for selecting a toaster function, and a display part  26   c  for displaying an operation state for a key input at the first selection part  26   a  or the second selection part  26   b.    
         [0015]     According to this, the related art toaster cum microwave oven carries out a function of a signal received from the first or second selection part  26   a  or  26   b  of the control panel  26 , for toasting the bread according to a kind of bread and a level of bread toasting the user selected.  
         [0016]     However, the related art toaster cum microwave oven has a problem in that the bread is not toasted as the user desired because the bread is toasted only according to kind of bread and a level of bread toasting the user selected without taking an inside state of the toaster into account.  
       SUMMARY OF THE INVENTION  
       [0017]     Accordingly, the present invention is directed to a toaster cum microwave oven, and a method for operating the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.  
         [0018]     An object of the present invention is to provide a toaster cum microwave oven, and a method for operating the same, in which bread is toasted to a level the user desires regardless of a toaster inside temperature and continued toasting.  
         [0019]     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
         [0020]     To achieve these objects and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the toaster cum microwave oven having a heater for toasting bread includes a first key input part for selecting a function of the microwave oven, a second key input part for selecting a function of the toaster, a memory for storing a voltage level to a heater according to the function of the toaster the user selects, a temperature sensor for sensing an inside temperature of the toaster, and a microcomputer for controlling a toasting time period according to a kind and a toasting level of bread the user selects, and an inside temperature of the toaster, and controlling the microwave oven according to a command received through the first key input part.  
         [0021]     The microcomputer sets a first heating time period according to a function of the toaster the user selects, a second heating time period according to the inside temperature of the toaster, and a third time period according to the voltage level, and sets a toasting time period by combining the first, second, and the third time periods. The microcomputer compensates for an error to be caused by the inside temperature of the toaster sensed at the temperature sensing part.  
         [0022]     In another aspect of the present invention, there is provided a method for operating a toaster cum microwave oven including the steps of selecting a function of the toaster, sensing an inside temperature of the toaster, (c) setting a toasting time period according to the selected function of the toaster, and the inside temperature of the toaster, and (d) toasting the bread for the set toasting time period.  
         [0023]     After sensing the inside temperature of the toaster, the step of compensating for an error further includes the step of subtracting/adding a temperature from/to the sensed inside temperature according to a time period starting from a time point the toaster finishes operation to a time point the toaster starts operation again, for compensating for an error to be caused by the sensed inside temperature. Or alternatively, The step of compensating for an error further includes the step of increasing/reducing the toasting time period according to a time period starting from a time point the toaster finishes operation to a time point the toaster starts operation again, for compensating for an error to be caused by the sensed inside temperature.  
         [0024]     The step (c) includes the steps of setting a first heating time period according to a function of the toaster the user selects, and a second heating time period according to the inside temperature of the toaster, and combining the first and second heating time periods for setting a toasting time period.  
         [0025]     In further aspect of the present invention, there is provided a toaster cum microwave oven having a heater for toasting bread, including a first key input part for selecting a function of the microwave oven, a second key input part for selecting a function of the toaster according to a kind and a toasting level of bread, a memory for storing a voltage level to a heater according to the kind and the toasting level of bread the user selects, a time counter for counting a time period starting from an end of operation of the toaster to a re-start of the operation, and a microcomputer for controlling a heating time period of the heater according to the kind and a toasting level of bread the user selects, a voltage level, and a time period counted with the time counter, and controlling operation of the microwave oven according to a command received through the first key input part.  
         [0026]     In still further aspect of the present invention, there is provided a method for operating a toaster cum microwave oven including the steps of selecting a function of the toaster according to a kind and a toasting level, (b) determining if the toaster is operated within a time period before the selection of a function of the toaster, (c) setting a toasting time period according to the user&#39;s selection of the function of the toaster, and a time period starting from a prior time point the toaster finishes operation to a time point the toaster starts operation again if the toaster is operated before, and (d) toasting the bread for the set toasting time period.  
         [0027]     The step (c) includes the steps of setting a first heating time period according to a function of the toaster the user selects, and a second heating time period according to a time period starting from a prior time point the toaster finishes operation to a time point the toaster starts operation again, and combining the first and second heating time periods for setting a toasting time period.  
         [0028]     The step (c) includes the steps of cooling down the inside of the toaster for a time period, sensing the inside temperature of the toaster, setting a first heating time period according to a function of the toaster the user selects, and a second heating time period according to a time period starting from a prior time point the toaster finishes operation to a time point the toaster starts operation again, and combining the first and second heating time periods for setting a toasting time period.  
         [0029]     In still yet further aspect of the present invention, there is provided a method for operating a toaster cum microwave oven including the steps of selecting a function of the toaster according to a kind and a toasting level, (b) determining if the toaster is operated within a time period before the selection of a function of the toaster, (c) sensing an inside temperature of the toaster, (d) setting a toasting time period according to the user&#39;s selection of the function of the toaster, and the inside temperature of the toaster if the toaster is operated before, and (e) toasting the bread for the set toasting time period.  
         [0030]     The method further includes the step of compensating for an error to be caused by the sensed inside temperature after the step (c). The step of compensating for an error further includes the step of subtracting/adding a temperature from/to the sensed inside temperature according to a time period starting from a time point the toaster finishes operation to a time point the toaster starts operation again, for compensating for an error to be caused by the sensed inside temperature. The step of compensating for an error further includes the step of increasing/reducing the toasting time period according to a time period starting from a time point the toaster finishes operation to a time point the toaster starts operation again, for compensating for an error to be caused by the sensed inside temperature.  
         [0031]     It is to be understood that both the foregoing description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings;  
         [0033]      FIG. 1  illustrates a disassembled perspective view of a related art microwave oven;  
         [0034]      FIG. 2  illustrates a disassembled perspective view of a related art toaster cum microwave oven;  
         [0035]      FIG. 3  illustrates a block diagram of a toaster cum microwave oven in accordance with a first preferred embodiment of the present invention;  
         [0036]      FIGS. 4A and 4B  illustrate a flow chart showing the steps of a method for operating the toaster cum microwave oven in  FIG. 3 ;  
         [0037]      FIG. 5  illustrates a block diagram of a toaster cum microwave oven in accordance with a second preferred embodiment of the present invention;  
         [0038]      FIGS. 6A and 6B  illustrate a flow chart showing the steps of a method for operating the toaster cum microwave oven in  FIG. 5 ;  
         [0039]      FIG. 7  illustrates a block diagram of a toaster cum microwave oven in accordance with a third preferred embodiment of the present invention; and  
         [0040]      FIGS. 8A and 8B  illustrate a flow chart showing the steps of a method for operating the toaster cum microwave oven in  FIG. 7 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0041]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In describing the embodiments, same parts will be given the same names and reference symbols, and repetitive description of which will be omitted.  
       First Embodiment  
       [0042]     A toaster cum microwave oven in accordance with a first preferred embodiment of the present invention will be described.  
         [0043]     Referring to  FIG. 3 , a control system of the toaster cum microwave oven includes a first key input part  201  for selecting different functions for operating the microwave oven, a second key input part  202  for selecting different menu for operating the toaster, and kind and level of toasting of bread, a memory  203  for storing a voltage level provided to a heater according to the kind and level of toasting of bread, a temperature sensor  205  for sensing an inside temperature of the toaster, a microcomputer  204  for controlling the toaster such that a heating time period of the bread is varied with kind and a toasting level of bread, a voltage level of toasting, the user selects, and an inside temperature of the toaster sensed through the temperature sensing part  205 , and controlling operation of the microwave oven according to a command received through the first key input part  201 , a first load operating part  206  for operating a load on the microwave oven in response to a control signal from the microcomputer  204  when a user&#39;s command is received through the first key input part  201 , a second load operating part  207  for operating a load on the toaster in response to a control signal from the microcomputer  204  when a user&#39;s command is received through the second key input part  202 , a heater  208  for being heated with a voltage from the second load operating part  207 , and a display part  209  for displaying operation states of the microwave oven and the toaster in response to a control signal from the microcomputer  204 .  
         [0044]     When the user selects kind and a toasting level of bread through the second key input part  202 , the toaster cum microwave oven sets a final time period of bread toasting by making a combination of a time period preset according to the kind and toasting level of bread, a heating time period according to an output voltage preset according to a toasting level of bread, and a heating time period preset according to an inside temperature of the toaster sensed through the temperature sensing part.  
         [0045]     That is, it is required that a toasting time period of soft bread is different from hard bagel. Moreover, since the toasting level differs depending on users, the toasting time period is adjusted according to the toasting level. For an example, the toasting level is classified into ‘rare’, ‘medium’, and ‘overdo’, and the heating time period is set according to the class. Thus, the heating time period is set according to kind and toasting level of the bread, and information on the set heating time period is stored in the memory  203 .  
         [0046]     Since the voltage to the heater  207  differs depending on toaster manufacturers and toasting levels, the heating time period differs depending on the toaster manufacturers. For an example, when the voltage to the heater is relatively high, the heating time period is reduced, and when the voltage to the heater is low, the heating time period is long.  
         [0047]     Moreover, since the inside temperature of the toaster is elevated, once the toaster is operated the heater  208  is heated quickly, and the bread is toasted within a short time period when the bread is toasted continuously. Therefore, the microcomputer  204  controls a heater heating time period according to the inside temperature sensed at the temperature sensing part  205 . For an example, if the inside temperature is higher than a room temperature or a reference temperature, the heating time period is reduced by a predetermined amount.  
         [0048]     Thus, the first embodiment toaster cum microwave oven set a toasting time period, taking a heating time period depending on kind of bread, a heating time period depending on a toasting level, a heating time period depending on the voltage to the heater  208 , and a heating time period depending on a temperature sensed at the temperature sensing part  205  into account.  
         [0049]     Though not shown, the first embodiment toaster cum microwave oven may further includes a fan for cooling the toaster, and a time counter for counting a time period starting from finish of toaster operation to a starting time of re-operation of the toaster.  
         [0050]     A method for operating the first embodiment toaster cum microwave oven of the present invention will be described.  FIGS. 4A and 4B  illustrate a flow chart showing the steps of a method for operating the toaster cum microwave oven in  FIG. 3 .  
         [0051]     Referring to  FIG. 4A , application of a power to the microwave oven is determined (S 11 ). As a result of the determination in the step S 11 , if it is determined that the power is applied, application of a user&#39;s cooking signal is determined (S 12 ).  
         [0052]     As a result of the determination in the step S 12 , if it is determined that no user&#39;s cooking signal is applied, a function other than the cooking function, such as a timer reset, is carried out (S 13 ). On the other hand, as a result of the determination in the step S 12 , if it is determined that the user&#39;s cooking signal is applied, it is determined whether the user applied a signal through the second key input part  202  for operating the microwave oven (S 14 ).  
         [0053]     As a result of the determination in the step S  14 , if the signal is applied through the second key input part  202 , the microcomputer  204  knows that the user intends to operate the toaster. In this instance, as shown in  FIG. 4B , the user selects kind and a toasting level of the bread (S 15 ).  
         [0054]     Then, detecting the kind and the toasting level of the bread the user selects through the second key input part  202 , the microcomputer  204  reads a first set time period ‘T1’ for the kind and the toasting level of the bread from the memory  203  (S 16 ).  
         [0055]     Then, the microcomputer  204  reads the inside temperature of the toaster from the temperature sensing part  205  (S 17 ). Then, the microcomputer  204  set a second time period T 2 , a heating time period for the inside temperature of the toaster (S 18 ). For an example, the higher the inside temperature than a room temperature or a reference temperature, the shorter the second time period T 2 , the lower the inside temperature than a room temperature or a reference temperature, the longer the second time period T 2 .  
         [0056]     The microcomputer  204  also reads a level of a voltage to be applied to the heater  208  according to a toasting level the user selects (S 19 ).  
         [0057]     Since a voltage level to be applied to the heater  208  for the same toasting level is set different between manufacturers, it is required that the heating time period is also set different between manufacturers. Therefore, the microcomputer  204  sets a third time period T 3  according to a level of the voltage (S 20 ). For an example, the higher the voltage level to the heater  208 , the shorter the third time period T 3 , the lower the voltage level to the heater  208 , the longer the third time period T 3 . An order for setting the first, second, and third time periods T 1 , T 2 , and T 3  may be varied.  
         [0058]     Then, the microcomputer  204  determines a final toasting time period Tt, i.e., an actual heater heating time period (S 21 ) by combining the first, second, and third time periods T 1 , T 2 , and T 3  set depending on selected kind and toasting level, the inside temperature of the toaster, and the voltage level of to be applied to the heater, respectively. There may be a variety of methods for determining the toasting time period Tt by using the first, second, and third time periods T 1 , T 2 , and T 3 . For an example, the toasting time period may be taken as an average of the first, second, and third time periods T 1 , T 2 , and T 3 . Or, alternatively, deviations of the first, second, and third time periods T 1 , T 2 , and T 3  from a reference time period may be obtained, and the toasting time period Tt may be determined by using the deviations. Or, as another alternative, the toasting time period Tt may be determined by subtracting or adding the deviations of second and third time period T 2  and T 3  from/to the first time period T 1 , respectively. The third method may be expressed as the following equation (1). 
 
 Tt=T   1 +( T   2 − T   2 ′)+( T   3 − T   3 ′)   (1) 
 
         [0059]     Where, T 2 ′ denotes a heating time period for a reference temperature, and T 3 ′ denotes a heating time period for a reference voltage.  
         [0060]     Once the toasting time period Tt is determined, application of user&#39;s cooking command is determined (S 22 ). As a result of determination in the step S 22 , if the user&#39;s cooking command is applied, the toasting is carried out as long as Tt (S 23 ).  
         [0061]     Then, pass of the toasting time period Tt is determined (S 24 ), if it is determined that the toasting time period Tt is passed, turn off of the power is determined (S 25 ). If the power is turned off, all routines are completed.  
         [0062]     On the other hand, as a result of the determination in the step S 14 , if no signal is applied through the second key input part  202 , application of signal through the first key input part  201  is determined (S 26 ). If the signal is applied through the first key input part  201 , a cooking function of the microwave oven is carried out (S 27 ).  
         [0063]     Thus, the first embodiment toaster cum microwave oven of the present invention determines a toasting time period Tt, taking kind and toasting level of bread the user selects, a voltage level applied to the toaster, and an inside temperature sensed through the temperature sensing part into account.  
       Second Embodiment  
       [0064]     A toaster cum microwave oven in accordance with a second preferred embodiment of the present invention will be described.  
         [0065]     Referring to  FIG. 5 , the toaster cum microwave oven includes a first key input part  301  for selecting different functions for operating the microwave oven, a second key input part  302  for selecting different menu for operating the toaster, and kind and level of toasting of bread, a memory  303  for storing a voltage level provided to a heater according to the kind and level of toasting of bread, a time counter  305  for counting a time period starting from an end of operation of the toaster to a re-start of the operation, a microcomputer  304  for controlling the toaster such that a heating time period of the bread is varied with kind and a toasting level of bread, a voltage level of toasting, the user selects, and a time period sensed through the time counter  305 , and controlling operation of the microwave oven according to a command received through the first key input part  301 , a first load operating part  306  for operating a load on the microwave oven in response to a control signal from the microcomputer  304  when a user&#39;s command is received through the first key input part  301 , a second load operating part  307  for operating a load on the toaster in response to a control signal from the microcomputer  304  when a user&#39;s command is received through the second key input part  302 , a heater  308  for being heated with a voltage from the second load operating part  307 , and a d displaying operation states of the microwave oven and the toaster in response to a control signal from the microcomputer  304 .  
         [0066]     Though not shown, the second embodiment toaster cum microwave oven may further includes a fan for cooling the toaster, and a temperature sensing part for sensing an inside temperature of the toaster.  
         [0067]     A method for operating the second embodiment toaster cum microwave oven of the present invention will be described.  FIGS. 6A and 6B  illustrate a flow chart showing the steps of a method for operating a toaster cum microwave oven.  
         [0068]     Referring to  FIG. 6A , application of a power to the microwave oven is determined (S 101 ). As a result of the determination in the step S 101 , if it is determined that the power is applied, application of a user&#39;s cooking signal is determined (S 102 ).  
         [0069]     As a result of the determination in the step S 102 , if it is determined that no user&#39;s cooking signal is applied, a function other than the cooking function, such as a timer reset, is carried out (S 103 ). On the other hand, as a result of the determinationi in the step S 102 , if it is determined that the user&#39;s cooking signal is applied, it is determined whether the user applies a signal through the second key input part  302  for operating the microwave oven (S 104 ).  
         [0070]     As a result of the determination in the step S 104 , if no signal is applied through the second key input part  302 , the microcomputer  204  determines if a signal is applied through the first key input part  301 . If a signal is applied through the first key input part  301 , the microcomputer  204  carries out a cooking function of the microwave oven.  
         [0071]     As a result of the determination in the step S 104 , if a signal is applied through the second key input part  302 , the microcomputer  304  determines if the toaster is operated for a time period before (S 105 ). This can be made by verifying application of a voltage to the heater  308  before.  
         [0072]     As a result of the determination in the step S 105 , if it is determined that the toaster is operated before, the microcomputer  304  calculates a time period Td starting from a prior end of operation to re-starting of operation from the time counter  305 . A time point of the re-starting of operation is the time point the user&#39;s command for operating the toaster is received.  
         [0073]     Then, referring to  FIG. 6   b , after detecting the kind and the toasting time period of bread the user selects through the second key input part  302  (S 107 ), the microcomputer  204  reads a first set time period ‘T11’ for the kind and the toasting level of the bread from the memory  303  (S 108 ).  
         [0074]     Then, the microcomputer  204  reads a voltage level to be provided to the heater  308  according to the toasting level the user selects (S 109 ), and sets a second time period T 12  according to the voltage level (S 110 ). For an example, the higher the voltage level, the shorter the second time period T 12 , the lower the voltage level, the longer the second time period T 12 .  
         [0075]     A third time period T 13  is set according to the time period Td calculated in the step S 106  (S 111 ). A short time period Td from the prior end of operation to re-start of operation implies a short cool down time period of the heater  308 . That is, the shorter the calculated time period Td, the higher the inside temperature of the toaster. Therefore, the shorter the calculated time period Td is, the shorter the third time period T 13  is set, and the longer the calculated time period Td is, the longer the third time period T 13  is set. An order for setting the first, second, and third time periods T 11 , T 12 , and T 13  may be varied.  
         [0076]     Then, the microcomputer  204  determines a final toasting time period Tt 1 , i.e., an actual heater heating time period (S 112 ) by combining the first, second, and third time periods T 11 , T 12 , and T 13 . There may be a variety of methods for determining the toasting time period Tt 1  by using the first, second, and third time periods T 11 , T 12 , and T 13 .  
         [0077]     Once the toasting time period Tt 1  is determined, application of user&#39;s cooking command is determined (S 113 ). As a result of determination in the step S 113 , if the user&#39;s cooking command is applied, the toasting is carried out as long as Tt 1  (S 114 ).  
         [0078]     Then, finish of toaster operation is determined (S 115 ). This can be made by determining pass of the toasting time period Tt 1 . If it is determined that the toasting time period Tt is passed, turn off of the power is determined (S 116 ). If the power is turned off, all routines are completed.  
         [0079]     Thus, the second embodiment toaster cum microwave oven of the present invention determines a toasting time period Tt 1 , taking kind and toasting level of bread the user selects, a voltage level applied to the toaster, and a time period starting from a prior end of operation to a re-starting of operation into account.  
       Third Embodiment  
       [0080]     A toaster cum microwave oven in accordance with a third preferred embodiment of the present invention will be described.  
         [0081]     Referring to  FIG. 7 , the toaster cum microwave oven includes a first key input part  401  for receiving an operation command for the microwave oven and selecting various menus, a second key input part  401  for receiving an operation command for the toaster and selecting various menus, a temperature sensing part  405  for sensing an inside temperature of the toaster in response to a toaster operation command received from a user through the second key input part, and a microcomputer  404  for controlling the toaster in response to a user&#39;s command received through the second key input part  402 , and the microwave oven in response to a user&#39;s command received through the first key input part  401 . The microcomputer  404  puts the fan  410  into operation for a time period when the toaster operation is finished, and compensates for a temperature difference according to a preset compensation condition depending on whether the temperature sensed at the temperature sensing part  405  is the same with a preset temperature, if a toaster operation command is received again through the second key input part  402  before pass of a preset time period.  
         [0082]     The toaster cum microwave oven also includes a first load operating part  406  for operating a load on the microwave oven in response to a control signal from the microcomputer  404 , a second load operating part  407  for operating a load on the toaster in response to a control signal from the microcomputer  404 , a heater  408  for being operated in response to an operation signal from the second load operating part  407 , a fan  410  for cooling down heat in the microwave oven and the toaster, a time counter  411  for counting an operation time period of the fan  410 , a display part  409  for displaying operation states of the microwave oven and the toaster in response to a control signal from the microcomputer  404 , and a memory  403  for storing voltage levels provided to a heater  408  according to the kind and level of toasting of bread.  
         [0083]     When the user applies an operation command through the first key input part  401  of the second -key input part  402 , the toaster cum microwave oven provides a control signal for operating a pertinent load.  
         [0084]     If the operation command is provided through the second key input part  402 , an existence, and a time period, of toaster heating operation before application of the present operation command is determined. That is, it is determined if the operation command is an initial operation or not.  
         [0085]     If there is a prior heating operation, a toasting condition will be set depending on a state of the toaster, and, if there is no a prior heating operation, it is determined that the operation is an initial operation, toasting-is carried out according to a selected condition, and the fan  410  is driven for a preset time period if the operation is finished.  
         [0086]     The user may apply a command for putting the toaster into operation again, while the fan  410  is operated after the heating operation of the toaster. If the command for putting the toaster into operation again is received, the microcomputer  404  reads the inside temperature of the toaster from the temperature sensing part  405 , and adjusts a toasting condition according to the inside temperature of the toaster. However, the inside temperature of the toaster sensed during the cooling fan  410  is operated is lower than an actual temperature. Because the fan  410  discharges hot air in the toaster to outside of the toaster, the inside temperature of the toaster becomes low, temporarily. However, when the fan  410  stops, the inside temperature rises again, due to the heat remained in the heater  408 . Therefore, there is a difference between the sensed temperature and the actual temperature.  
         [0087]     For compensating for the temperature difference, a temperature compensating system or a time compensating system preset in advance is employed in a fabrication process. In the case of the temperature compensating system, the microcomputer  404  estimated a difference between the sensed inside temperature and the actual temperature, and the toasting time period is adjusted according to the estimated temperature difference. In the case of the time compensation system, the toasting time period is adjusted with a time period starting from a time point a toasting operation end to a time point operation command of the toaster is received again.  
         [0088]     A method for operating the toaster cum microwave oven in accordance with a third preferred embodiment of the present invention will be described.  FIGS. 8A and 8B  illustrate a flow chart showing the steps of a method for operating the toaster cum microwave oven in  FIG. 7 .  
         [0089]     Referring to  FIG. 8A , application of a power to the microwave oven is determined (S 201 ). As a result of the determination in the step S 201 , if it is determined that the power is applied, application of a cooking signal from a user is determined, (S 202 ).  
         [0090]     As a result of the determination in the step S 202 , if it is determined that there is no application of a cooking signal from a user, a function other than the cooking, such as a timer reset is carried out. (S 203 ). Opposite to this, as a result of the determination in the step S 202 , if it is determined that there is application of a cooking signal from a user, user&#39;s application of the signal through the second key input part  402  for operating the microwave oven is determined.  
         [0091]     As a result of the determination in the step S 204 , if there is no user&#39;s application of the signal through the second key input part  402 , application of a signal through the first key input part  401  is determined (S 223 ). If the signal is received through the first key input part  401 , a cooking function of the microwave oven is carried out (S 228 ).  
         [0092]     Opposite to this, as a result of the determination in the step S 204 , if there is application of the signal through the second key input part  402 , the microcomputer  404  determines if there is a prior toaster operation or not (S 205 ). This can be made by determining if there is application of a voltage before.  
         [0093]     As a result of the determination in the step S 205 , if there is no prior heating operation, the operation is determined to be an initial operation, the toasting is carried out according to a toasting condition the user selects (S 206 ). After finish of the step S 206  is determined (S 207 ), and, if finished, the fan  410  is operated for a preset time period for cooling down an inside of the toaster (S 208 ).  
         [0094]     Then, pass of the preset time period is determined (S 209 ), and, as a result of the determination in the step S 209 , if the preset time is not passed yet, re-reception of the operation command is determined (S 210 ).  
         [0095]     As a result of the determination in the step S 210 , if the operation command is received again, an inside temperature (RT) of the toaster is reads through the temperature sensing part  405  (S 211 ). Then, a toasting condition is set by making a temperature or time compensation according to a preset compensation condition (S 213 ).  
         [0096]     The temperature compensation process will be described.  
         [0097]     When an operation command is received again in the middle of operation of fan after finish of toaster operation, there is a difference between the inside temperature (RT) the microcomputer  404  reads and an actual temperature because it is temporarily sensed that the temperature drops. Taking the temperature difference into account, the temperature compensation is made so that the microcomputer  404  detects an accurate temperature.  
         [0098]     That is, the compensation temperature CT is subtracted/added from/to the sensed inside temperature RT, to fix a set temperature DT close to an actual temperature. By combining a heating time period T 2  for the set temperature DT, the kind and the toasting level of bread, and a heating time period T 1  for the voltage level, a toasting time period Tt 2  is determined.  
         [0099]     The compensation temperature CT is calculated from a time period Td starting from a time point the toaster finished operation to a time point the toaster starts operation again, or an operation time period of the fan  410 . For an example, if an operation time period of the fan is long, the compensation temperature CT is set low, and if the operation time period of the fan is short, the compensation temperature CT is set high. Because, if the operation time period of the fan  410  long, the inside temperature to the toaster drops as much, and the heat of the heater  408  cools down, a small value of compensation temperature CT is subtracted from the sensed inside temperature RT. Opposite to this, if the operation time period of the fan  410  short, because the heat of the heater  408  can not be cooled much, a great value of compensation temperature CT is subtracted from the sensed inside, temperature RT.  
         [0100]     The time compensation process will be described.  
         [0101]     For compensating for a difference between the inside temperature RT the microcomputer  404  reads and the actual temperature, a compensation time period dT is set for the difference between the sensed inside temperature RT and the actual temperature, and a toasting time period Tt 2  is fixed by using the compensation time period dT. That is, the toasting time period Tt 2  is fixed by combining the kind and toasting level of bread the user selects, a heating time period T 1  for a voltage level, a heating time period T 2  for the sensed inside temperature RT, and the compensation time period dT.  
         [0102]     The compensation time period dT is calculated from a time period Td starting from a time point the toaster finishes operation to a time point the toaster starts operation again, or an operation time period of the fan  410 . The short time period Td from a time point starting from an end of prior operation to a time point operation is started again, or the short operation time period of the fan  410  implies a short cooling down period of the heater  408  as much. In other words, the shorter the time period Td, the higher the inside temperature of the toaster. Therefore, the shorter the time period Td, the shorter the compensation time period dT, the longer the time period Td, the longer the compensation time period dT.  
         [0103]     Once a toasting condition, such as toasting time period Tt 2 , is set by the temperature compensation or a time compensation in the step S 213 , toasting is carried out until the toasting is finished according to the set toasting condition (S 214 -S 215 ).  
         [0104]     As a result of the determination in the step S 209 , if the fan  410  is operated for a preset time period, after the fan  410  is stopped, re-reception of the operation command from the user is determined (S 217 ). As a result of the determination in the step S 217 , if the operation command is received from the user again, the toasting time period is set according to the toasting condition the user selects and the temperature RT the temperature sensing part  405  reads, and toasting is carried out until toasting is finished (S 218 -S 219 ).  
         [0105]     As a result of the determination in the step S 205 , if there is heating operation before the operation command, it is determined if the fan  410  is in operation or not (S 220 ). Then, as a result of operation in the step S 220 , if the fan  410  is not in operation presently, the toasting time period is set according to the toasting condition the user selects and the temperature RT the temperature sensing part  405  reads, and toasting is carried out until toasting is finished (S 221 -S 222 ).  
         [0106]     As has been described, since the toaster cum microwave oven, and method for operating the same sets a toasting time period taking an inside temperature of the toaster, and an idle time period into account, a state of toast the user desires can be provided, which improves satisfaction and reliability of user for the product.  
         [0107]     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.