Patent Abstract:
A microwave oven with an electric device is provided in which the microwave oven includes an electric device control button and a control unit. The electric device control button drives the electric device by manipulation of a user and generates a power amount control signal to control power supplied to the electric device. The control unit controls the amount of power supplied to the electric device in response to the power amount control signal. The power amount control signal is a single pulse signal that is generated whenever the electric device control button is manipulated; and the amount of power supplied to the electric device is determined depending upon a number of occurrences of the single pulse signal.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of Korean Application No. 2002-20569, filed Apr. 16, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to a microwave oven, and more particularly, to a hood and microwave oven combination that has a control apparatus to precisely control an amount of power supplied to the microwave oven. 
   2. Description of the Related Art 
   A hood and microwave oven combination is a microwave oven with a ventilation unit. The hood and microwave oven combination is mounted over a gas oven or electric oven. The hood and microwave oven combination serves to both fundamentally perform a microwave oven function and exhaust smoke and odor, which are formed when the gas or electric oven is operated, to the outside by the ventilation unit. 
   The hood and microwave oven combination is generally equipped with an illumination unit and the ventilation unit to provide convenience when the gas oven or the electric oven is used. The illumination unit lights up a space over the gas oven or the electric oven, while the ventilation unit sucks the smoke and the odor and exhausts the smoke and the odor to the outside. While food is cooked using the gas oven or the electric oven, the illumination unit and the ventilation unit are generally used at the same time. 
   As occasion demands, the illumination unit and the ventilation unit of the hood and microwave oven combination can be adjusted in illumination intensity and suction and exhaust capacity, respectively. When an interior of a room is dark, the illumination unit is turned up; and when food is being cooked, which produces substantial smoke and odor, the ventilation unit is maximally operated to smoothly exhaust the smoke and the odor. The adjustment of the illumination intensity of the illumination unit and the ventilation capacity of the ventilation unit is carried out though a phase control process, as shown in  FIGS. 1A and 1B , which will be described below. 
     FIGS. 1A and 1B  are graphs showing amounts of power according to driving points in a hood and microwave oven. As shown in  FIG. 1A , half of a period is divided into eight equal intervals, and display interrupts  104  are generated at points indicated by solid lines to drive a display of the microwave oven. Since interrupts controlling the illumination unit and the ventilation unit of the microwave oven have to be generated at intervals that are shorter than intervals for the display interrupts  104 , the half of a period is divided into sixteen equal intervals, and the illumination unit and the ventilation unit controlling interrupts  106  are generated at points indicated by dotted lines to drive the display of the microwave oven. 
   The illumination intensity of an illumination unit and the driving capability of a ventilation motor are determined depending upon which interrupt point is selected from sixteen equally spaced interrupt points. For the ventilation unit, if an interrupt point {circle around (4)} is selected as a driving point in  FIG. 1A , a ventilation motor driving interrupt is generated at the interrupt point {circle around (4)} and power of a size corresponding to an area of a shaded portion is supplied to the ventilation motor.  FIG. 1B  shows a case where a ventilation motor driving point is {circle around (9)} and the power of a size corresponding to the area of a shaded portion is supplied to the ventilation motor. In the above-described cases, the stopping points are all points {circle around (14)}. Certain amounts of power are supplied at every half a period, so constant power can be continuously supplied to the ventilation motor while the ventilation motor is driven. 
     FIG. 2  is a graph showing relationships between a conventional external power source of a conventional microwave oven, an interval of interrupts, a ventilation motor output curve and a lamp output curve. Referring to  FIG. 2 , a variation of the lamp output curve  208  with respect to a driving point is linear, while a variation of a ventilation motor output curve  210  is non-linear. When the lamp and ventilation motor of the microwave oven are driven at a display interrupt point {circle around (1)} (a driving point becomes {circle around (1)}), a maximum output can be obtained. As the driving point approaches a display interrupt {circle around (13)} through a display point {circle around (3)}, the output of the lamp and ventilation motor of the microwave oven gradually increases and reaches zero at a display interrupt point {circle around (15)}. As a result, in order to drive the lamp and ventilation motor of the microwave oven so as to generate a maximum output of the lamp and ventilation motor of the microwave oven, the driving point of the lamp and ventilation motor of the microwave oven has to be set near the display interrupt point  {circle around (1)}; to decrease the output of the lamp and ventilation motor of the microwave oven, the driving point has to be set near the display interrupt point  {circle around (15)}. 
   The ventilation motor output curve  210 , which varies non-linearly, has a particularly large variation over intervals between display interrupt points {circle around (7)} to {circle around (11)}, so the ventilation motor needs to be controlled more precisely in the intervals between interrupt points {circle around (7)} to {circle around (11)} than other intervals. To control the ventilation motor more precisely, new interrupts can be generated at narrower intervals than the sixteen equal intervals of half of a period. However, an additional timer may need to be added so as to generate new interrupts at narrower intervals, so a restriction occurs that a high-level microprocessor including a sufficient number of timers may need to be employed. This restriction can cause of an increase in manufacturing cost. Further, the interference of a new interrupt with an existing interrupt can delay an operation caused by the existing interrupt and the delay can deteriorate a reliability of products. 
   SUMMARY OF THE INVENTION 
   Accordingly, a microwave oven having a control apparatus for controlling an amount of supplied power is provided, which is capable of generating ventilation motor and lamp driving interrupts together with a display driving interrupt using an existing timer provided to generate the display driving interrupt, and which is capable of precisely controlling the amount of power supplied to a ventilation motor by a manipulation of a ventilation motor control button. 
   Additional objects 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. 
   In order to accomplish the above object, a microwave oven with an electric device is provided, comprising: an electric device control button driving the electric device by manipulation of a user and generating a power amount control signal to control power supplied to the electric device; and a control unit controlling the amount of power supplied to the electric device in response to the power amount control signal. 
   The power amount control signal may be a single pulse signal that is generated whenever the electric device control button is manipulated; and the amount of power supplied to the electric device may be determined depending upon a number of occurrences of a single pulse signal. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects 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: 
       FIGS. 1A-1B  are graphs showing amounts of power according to driving points in a conventional hood and microwave oven; 
       FIGS. 2A and 2B  are graphs showing relationships between an external power source of a conventional microwave oven, an interval of interrupts, a ventilation motor output curve and a lamp output curve; 
       FIGS. 3A and 3B  are graphs showing relationships between an external power source of a microwave oven according to an embodiment of the present invention, an interval of interrupts, a ventilation motor output curve and a lamp output curve; 
       FIG. 4  is a block diagram of a microwave oven control apparatus according to the embodiment of the present invention  FIGS. 5A-5F  are views showing a concept of phase control according to the embodiment of the present invention; 
       FIG. 6  is a flowchart showing a method of controlling an output of the ventilation motor of the microwave oven in accordance with the embodiment of the present invention; 
       FIG. 7  is a flowchart showing a method of controlling the driving of the lamp of the microwave oven; and 
       FIG. 8  is a flowchart showing a method of determining a ventilation motor driving point and a lamp driving point. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A microwave oven having a control unit precisely controlling the amount of supplied power is described with reference to  FIGS. 3  to  8 .  FIG. 3  is a graph showing relationships between an external power source of a microwave oven of the present invention, an interval of interrupts, a ventilation motor output curve and a lamp output curve. Referring to  FIG. 3 , the capacity of a ventilation motor is variably controlled by precisely adjusting interrupt points {circle around (8)} and  {circle around (10)} within an interval between interrupt points  {circle around (7)} and {circle around (9)} and another interval between interrupt points {circle around (9)} and {circle around (11)}, respectively. 
     FIG. 4  is a block diagram of the microwave oven control apparatus according to an embodiment of the present invention. As depicted in  FIG. 4 , a control unit  402  includes a reload counter  404  and a reload register  406 . The reload counter  404  is synchronized with a clock signal  426  to carry out a count operation. If the reload counter  404  counts to an allowed maximum value and an overflow occurs, the reload counter  404  loads the value of the reload register  406  and counts from the loaded value to the maximum value. That is, the reload counter  404  is initialized to the value of the reload register  406  just after the occurrence of the overflow and performs a count operation. The greater the value of the reload register  406  becomes, the narrower a count range of the reload counter  404 , thus reducing a range of the overflow. On the contrary, the smaller the value of the reload register  406  becomes, the wider the count range of the reload counter  404 , thus increasing the range of the overflow. 
   The value of the reload register  406  can be determined by manipulation of a ventilation motor control button  410  of a ventilation motor  414  of the microwave oven. The ventilation motor control button  410  is used to manipulate the ventilation motor  414 . When the ventilation motor control button  410  is manipulated while the ventilation motor is operated, the value of the reload register  406  can be changed. The ventilation motor control button  410  generates a single pulse signal whenever the ventilation motor control button  410  is manipulated by a user. The single pulse signal increases the value of the reload register by one. That is, the single pulse signal, which is generated whenever the ventilation motor control button  410  is manipulated, acts like a clock signal and increases the value of the reload register  406  in stages. The value of the reload register  406  is increased to the maximum value of the allowed capacity of the reload register  406 , and initialized when overflow occurs. Accordingly, if the ventilation motor control button  410  is repeatedly manipulated while the ventilation motor  414  is operated, the value of the reload register  406  is increased to the maximum value, initiated to zero after reaching the maximum value, and increased again after being initiated to zero. The value of the reload register  406  is visually displayed on a display  434 . A user can observe a magnitude of an output of the ventilation motor  414  by viewing the value of the reload register  406  that varies with the manipulation of the ventilation motor control button  410 . 
   An interrupt generator  420  generates an interrupt signal  424  whenever overflow occurs in the reload counter  404 . The interval of occurrence of overflows can vary with the manipulation of the ventilation motor control button  410 . The control unit  402  processes the interrupt signal  424  to generate one of a ventilation motor drive signal  428 , a lamp drive signal  430  and a display drive signal  436  that are used to control a ventilation motor drive unit  412 , a lamp drive unit  416  and a display drive unit  432 , respectively. A lamp  418  and the display  434  have linear characteristics, and so are not affected by the fine adjustment of a phase according to the present invention. 
     FIGS. 5A-5F  are views showing the concept of phase control according to the present invention.  FIGS. 5A  to  5 C to show the phase control of a display interrupt  304  in an interval between interrupt points {circle around (7)} to {circle around (9)}.  FIGS. 5D  to  5 F show phase control in an interval between interrupt points {circle around (9)} and {circle around (11)}. An interrupt point can be further precisely controlled by precisely varying a fine adjustment interrupt {circle around (8)} within an interval between display interrupt points {circle around (7)} and {circle around (9)}.  FIGS. 5A  to  5 C show cases where the values of the reload register  406  are a minimum value, a middle value and a maximum value, respectively. In  FIGS. 5D  to  5 F, an interrupt point can be further precisely controlled by precisely varying a fine adjustment interrupt {circle around (10)} within an interval between display interrupt points {circle around (9)} and {circle around (11)}.  FIGS. 5D  to  5 F show cases where the values of the reload register  406  are a minimum value, a middle value and a maximum value, respectively. The maximum and minimum values of fine adjustment interrupts {circle around (8)} and {circle around (9)} correspond to the maximum and minimum values of the capacity of the reload register  406  of  FIG. 4 , respectively. 
     FIG. 6  is a flowchart showing a method of controlling the output of the ventilation motor  414  of a microwave oven in accordance with the embodiment of the present invention. As shown in  FIG. 6 , when the ventilation motor control button  410  is turned on at S 602 , the ventilation motor  414  is driven at S 604 . In such a case, if the driving point of the ventilation motor  414  is {circle around (8)} at S 606  and a user finely adjusts the driving point by manipulating the ventilation motor control button  410  at S 608 , the value of the reload register  406  is slightly increased. If the value of the reload register  406  reaches the maximum value by the repeated manipulation of the user of the ventilation motor control button  410  at S 612 , the driving point of the ventilation motor  414  is moved to {circle around (9)} at S 614 , and the driving of the ventilation motor  414  is started whenever a display interrupt {circle around (9)} occurs at S 604 . 
   If the driving point is {circle around (7)} at S 616 , the value of the reload register  406  is minimized at S 618 , the driving point is forcibly moved to {circle around (8)} at S 620 , and the driving of the ventilation motor  414  is started at S 604 . The fine adjustment of the driving point of the ventilation motor  414  described above can be carried out by forcibly moving the driving point to {circle around (8)} under the condition that the value of the reload register  406  is minimized. 
   If the driving point is {circle around (13)} at S 622 , the driving of the ventilation motor  414  is stopped at S 624 . If the driving point is zero at S 626 , this means that no value is set in the reload register  406 . In this case, the driving point is forcibly moved to {circle around (3)} at S 628  to drive the ventilation motor  414  at S 604 . Such an operation is carried out within half of a period of supplied power, and a same operation is carried out in a remaining half of the period with its phase reversed. The precise control of an interrupt point {circle around (10)} can be performed within an interval between display interrupt points {circle around (9)} and {circle around (11)} for half a period. 
     FIG. 7  is a flowchart showing a method of controlling the driving of the lamp of the microwave oven. As shown in  FIG. 7 , when a lamp control button  422  is turned on at S 702 , the lamp  418  is driven at S 704 . If the driving point is {circle around ( 13 )} while the lamp  418  is being driven at S 704 , the driving of the lamp  418  is stopped at S 708 . If the driving point Is zero at S 710 , that means that no value is set in the reload register  406 . In this case, the driving point is forcibly moved to {circle around ( 3 )} at S 712 , and the ventilation motor  414  is driven at  5704 . 
     FIG. 8  is a flowchart showing a method of determining a ventilation motor driving point and a lamp driving point. As shown in  FIG. 8 , if the value of the reload register  406  is not set at S 804  while display interrupts  304 , as shown in  FIG. 3A , are generated (see S 802 ), “50” is assigned to the reload counter  404  at S 806  to generate fine adjustment interrupts  306 , as shown in  FIGS. 5A  to  5 F. In this case, “50” is the value that is calculated when the normal interval of occurrence of the interrupts is “100.” That is, in this case, fine adjustment interrupts  306  are generated at sixteen equally spaced interrupt points between eight equally spaced display interrupt points. 
   If the interrupt {circle around (8)} is generated at S 808  in the state in which the value of the reload register  406  is set to a certain value, the current value of the reload register  406  is assigned to the reload counter  404  at S 810  to enable the fine adjustment. 
   If an interrupt {circle around (9)} is generated at S 812 , “100” (the value of the reload register  406 ) is assigned to the reload counter  404  as the reload counter value at S 814 . In this case, the value of the reload register  406  is the interval between the interrupt points {circle around (7)} and {circle around (8)}. If a next interrupt is generated in the state in which the value of the reload register  406  is “30”, the interval of interrupts that are generated thereafter is fixed to “30.” Accordingly, when the value between the interrupt points {circle around (7)} and {circle around (9)} is set to “100,” “70” is added to the interrupt point {circle around (8)} so as to allow the value between the interrupt points {circle around (7)} and {circle around (9)} to “100. ” interrupts are generated according to the value assigned to the reloaded counter  404  at S 816 . 
   If an interrupt {circle around (13)} is generated at S 818  in the process of the generation of interrupts at S 818 , the operations of the ventilation motor  414  and the lamp  418  are stopped at S 820 . If a current interrupt point is a lamp driving point in the state in which the interrupt {circle around (13)} is not generated at S 822 , the lamp  418  is driven at S 824 . If a current interrupt point is a ventilation motor driving point in the state in which the interrupt {circle around (13)} is not generated at S 826 , the ventilation motor  414  is driven at S 828 . 
   In the state in which a display interrupt  304  driving the display  434  and a fine adjustment interrupt  306  driving the ventilation motor  414  and the lamp  418  are generated, if a display interrupt  304  is generated at S 830 , the display  434  is driven at S 832 . If a fine adjustment interrupt  306  is generated, the ventilation motor  414  and the lamp  418  are driven at S 834 . As described above, the apparatus for controlling the microwave oven can generate interrupts using the single reload counter  404  to drive the display  434 , the ventilation motor  414  and the lamp  418 . 
   The microwave oven having a control apparatus is provided, which is capable of generating the ventilation motor driving interrupt and the lamp driving interrupt together with the display driving interrupt using the existing timer provided to generate the display driving interrupt, thus maximizing the efficiency of use of the timer of the microwave oven, and which is capable of precisely controlling the magnitude of power supplied to the ventilation motor, thus freely controlling the output of the ventilation motor. 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): 7