Abstract:
A bread maker including a pair of kneading drums inside an oven compartment, to which are attached opposite ends of a mixing bag containing bread ingredients, the kneading drums reversing rotary direction periodically; a drum driving part in an electric component compartment rotating the kneading drums; a rotation sensing part sensing a rotation rate of one of the kneading drums; and a controller storing the rotation rate sensed by the rotation sensing part while the one of the kneading drums rotates during a first predetermined period of time, comparing the stored rotation rate with a rotation rate sensed by the rotation sensing part while the one of the kneading drums rotates during a next predetermined period of time, and stopping the drum driving part when a difference between the stored rotation rate and the sensed rotation rate for the next period of time exceeds an allowable limit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims the benefit of Korean Application No. 2002-42588, filed Jul. 19, 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 to a bread maker and a method of controlling the bread maker.  
           [0004]    2. Description of the Related Art  
           [0005]    Generally, making bread is so complicated that it is difficult for an average person to manually make satisfactory bread at home. That is, making the bread includes multiple steps of mixing ingredients such as flour, sugar, yeast, etc., to form a dough; kneading the dough, leavening the dough; baking the dough; and so on.  
           [0006]    Therefore, various bread makers have been developed to allow a user to easily make bread. The bread maker automatically performs the foregoing multiple steps and provides finished bread to the user.  
           [0007]    For example, a bread maker disclosed in Korean Patent Publication No. 1991-10203 includes a pair of parallel kneading drums at upper and lower parts of an oven compartment that reverse rotary direction periodically, a baking tray between the pair of kneading drums, a heater heating the inside of the oven compartment, a bar code scanner, etc.  
           [0008]    In the bread maker, disclosed in Korean Patent Publication No. 1991-10203, upper and lower ends of a mixing bag filled with flour, water, etc., are attached to the upper and lower kneading drums, and then the mixing bag is reciprocated up and down for a predetermined period of time, thereby kneading the dough in the mixing bag.  
           [0009]    After completing the kneading of the dough, the mixing bag is automatically separated from the upper kneading drum, and wound on the lower kneading drum, with the dough being squeezed out of the mixing bag and into the baking tray. Thereafter, a heater heats the inside of the oven compartment, thereby leavening and baking the dough for a predetermined period of time.  
           [0010]    The bread is made according to a bar code that is printed on the mixing bag that includes information on kneading time, leavening time, baking time, etc., for a particular recipe. That is, the bar code is read by the bar code scanner and the read data are transmitted to a controller, so that the controller controls the kneading drums, the heater, etc., on the basis of the read data.  
           [0011]    However, in the conventional bread maker, while the mixing bag is reciprocated up and down to knead the dough, if the upper and lower kneading drums do not rotate synchronously, or if the mixing bag separates from the upper or lower kneading drum because, for example, the mixing bag tears, the mixing bag is incorrectly attached to the upper and lower kneading drums, etc., internal components of the bread maker may be damaged.  
         SUMMARY OF THE INVENTION  
         [0012]    It is an aspect of the present invention to provide a bread maker and a control method thereof, that can prevent internal components of the bread maker from being damaged due to non-synchronous rotation between the upper and lower kneading drums, an incorrect installation of a mixing bag, etc.  
           [0013]    Additional aspects and advantages of the invention will be set forth in part in the description that follows, and, in part, will be obvious from the description, or may be learned by practice of the invention.  
           [0014]    To achieve the above and/or other aspects according to the present invention, there is provided a bread maker including a main body divided into an oven compartment and an electric component compartment; a pair of parallel kneading drums spaced apart from each other inside the oven compartment, to which are attached opposite ends of a mixing bag containing ingredients for bread, the kneading drums reversing rotary direction periodically; a drum driving part in the electric component compartment rotating the kneading drums in clockwise and counterclockwise directions; a rotation sensing part sensing a rotation rate of one of the kneading drums; and a controller storing the rotation rate sensed by the rotation sensing part while the one of the kneading drums rotates during a first predetermined period of time, comparing the stored rotation rate with a rotation rate sensed by the rotation sensing part while the one of the kneading drums rotates during a next predetermined period of time, and stopping the drum driving part when a difference between the stored rotation rate and the sensed rotation rate for the next period of time exceeds an allowable limit.  
           [0015]    The rotation sensing part includes a disk part rotating with the one of the kneading drums, and having at least one projection radially extending from a circumference thereof; and a disk sensor emitting a light toward the disk part and outputting a pulse signal according to interruption of the light by rotation of the at least one projection of the disk part.  
           [0016]    The disk part includes a first disk having a single projection; and a second disk having a plurality of projections along a circumference thereof at regular intervals.  
           [0017]    The disk sensor comprises a light emitting part and a light receiving part facing each other with the disk part therebetween, the disk sensor outputting a pulse signal when the at least one projection of the disk part interrupts light emitted from the light emitting part to the light receiving part.  
           [0018]    The controller includes a memory storing the pulse signal output during the first period of time, and the controller compares a difference in pulse widths between the pulse signal stored in the memory and the pulse signal output from the pulse generator during the next period of time.  
           [0019]    To achieve the above and/or other aspects according to the present invention, there is provided a method of controlling a bread maker having an oven compartment and an electric component compartment, a pair of parallel kneading drums inside the oven compartment to which are attached opposite ends of a mixing bag containing bread ingredients, the kneading drums reversing rotary direction periodically, and a drum driving part in the electric component compartment rotating the kneading drums clockwise and counterclockwise, the method including sensing a rotation rate of one of the kneading drums for a first predetermined period of time; storing the sensed rotation rate; comparing the stored rotation rate with the rotation rate sensed while the one of the kneading drums rotates during a next period of time; and stopping the drum driving part when a difference between the stored rotation rate and the rotation rate sensed during the next period of time exceeds an allowable limit.  
           [0020]    The bread maker further includes a rotation sensing part including a disk part rotating with the one of the kneading drums and having a plurality of projections around a circumference thereof at regular intervals; and a disk sensor outputting a pulse signal according to interruption, by the projections of the disk part, of light emitted toward the disk part, wherein the sensed rotation rate that is stored is based upon the pulse width of the pulse signal output from the disk sensor while the one of the kneading drums rotates for the predetermined period of time.  
           [0021]    Comparing the stored rotation rate and the sensed rotation rate of the next period of time includes comparing pulse widths of the pulse signals output during the first period of time and the next period of time, respectively.  
           [0022]    The method further includes providing a warning when a difference between the stored rotation rate and the sensed rotation rate of the next period of time exceeds an allowable limit.  
           [0023]    These together with other aspects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part thereof, wherein like numerals refer to like parts throughout. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    These and other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompany drawings, of which:  
         [0025]    [0025]FIG. 1 is a perspective view of a bread maker according to an embodiment of the present invention;  
         [0026]    [0026]FIG. 2 is a perspective view of an electric component compartment of the bread maker shown in FIG. 1;  
         [0027]    [0027]FIG. 3 is an exploded perspective view of a portion of the electric component compartment of FIG. 2;  
         [0028]    [0028]FIG. 4 is a front view of a mixing bag used in the bread maker according to the embodiment of the present invention;  
         [0029]    [0029]FIG. 5 is a control block diagram of the bread maker according to the embodiment of the present invention;  
         [0030]    [0030]FIGS. 6A and 6B illustrate pulse signals output from a rotation sensor according to the embodiment of the present invention; and  
         [0031]    [0031]FIG. 7 is a flowchart illustrating control of the bread maker according to the embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0032]    Hereinafter, an embodiment of the present invention will be described in detail with reference to the attached drawings, wherein the like reference numerals refer to the like elements throughout. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein; rather, this embodiment is provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.  
         [0033]    As shown in FIGS. 1 through 3, a bread maker according to an embodiment of the present invention includes a main body  1  divided into an oven compartment  10  and an electric component compartment  20 , a door  3  in the front of the main body  1  to open and close the front opening of the oven compartment  10 , and a control panel  5  in the front of the main body  1  to allow a user to control the bread maker and know the state of the bread maker. Inside the oven compartment  10 , upper and lower kneading drums  11  and  13  are provided in parallel and reversibly rotate. Opposite ends  8  of a mixing bag  7  (refer to FIG. 4) filled with raw materials (ingredients) for bread are attached to projections  12  on the upper and lower kneading drums  11  and  13 , and the mixing bag  7  is wound.  
         [0034]    In a lower part of the oven compartment  10 , there is a baking tray  15  in which the dough is baked between the upper and lower kneading drums  11  and  13 . In a lower part of the oven compartment  10 , there is a baking tray  15  in which the dough is baked between the upper and lower kneading drums  11  and  13 . The baking tray  15  includes first and second trays  15   a  and  15   b , each having an “L”-shaped section symmetrical to one another that combine into a box shape having an open top. In an upper part of the oven compartment  10 , a pair of squeezing members  17  is between the upper kneading drum  11  and the baking tray  15  that kneads the dough contained in the mixing bag  7  within the baking tray  15 , preventing the dough from moving outside the baking tray  15 .  
         [0035]    At upper and lower parts of the inside walls of the oven compartment  10  and the door  3  are heaters  19  for heating the inside of the oven compartment  10 .  
         [0036]    The electric component compartment  20  includes a first component compartment  21  placed beside the oven compartment  10  and a second component compartment  23  placed behind the oven compartment  10 . Inside the first component compartment  21  is a drum driving part  25  that rotates the upper and lower kneading drums  11  and  13  in clockwise and counterclockwise directions. Inside the second component compartment  23  is a bar code scanner  29  that reads a bar code  9  printed on or applied to the mixing bag  7  that is wound on the upper and lower kneading drums  11  and  13 . The bar code scanner  29  may move close to, and distantly from, an outer circumference of the upper kneading drum  11 .  
         [0037]    The drum driving part  25  includes a motor  26  that rotates the lower kneading drum  13 , and a belt  27  that transmits a rotary movement of the lower kneading drum  13  to a rotation shaft  28  of the upper kneading drum  11 .  
         [0038]    A rotation sensing part  40  senses rotation of at least one of the upper and lower kneading drums  11  and  13 , and a controller  70  (described below) stops the drum driving part  25  when a pulse signal output by the rotation sensing part  40  is greater than a predetermined allowable pulse width.  
         [0039]    The rotation sensing part  40  includes a disk part  41  attached to the rotation shaft  28  of the upper kneading drum  11 , and a rotation sensor  61  placed near the disk part  41  that outputs a pulse signal by sensing the rotation of the disk part  41 .  
         [0040]    The disk part  41  includes a first disk  36  that allows the rotation sensor  61  to sense one turn of the upper kneading drum  11 , and a second disk  37  that allows the rotation sensor  61  to sense a rotation of the upper kneading drum  11  that is less than one revolution.  
         [0041]    The first disk  36  is a circular plate  43 , which is separated from the second disk  37  by a cylindrical part  52  and connected to the rotation shaft  28  of the upper kneading drum  11  using a washer  54  and a bolt  56 . The circular plate  43  is formed with a single projection  44  radially extended therefrom. Hence, the first disk  36  rotates with the upper kneading drum  11  and allows the rotation sensor  61  to sense one revolution of the upper kneading drum  11 .  
         [0042]    The second disk  37  is a circular plate  47  with a shaft combining hole  46  used to attach the circular plate  47  to the rotation shaft  28  of the upper kneading drum  11 . The circular plate  47  has a plurality of slots  49  along the circumference thereof at regular intervals, forming a plurality of projections  48 . For example, in the embodiment shown in FIG. 3, the second disk  37  has twenty-four slots  49 , forming twenty-four projections  48 . Hence, the second disk  37  rotates with the upper kneading drum  11  and allows the rotation sensor  61  to sense a rotation of the upper kneading drum  11  that is less than one complete turn.  
         [0043]    The rotation sensor  61  includes a first disk sensor  63  sensing the single projection  44  of the first disk  36  and outputting one pulse signal per one revolution of the upper kneading drum  11 , and a second disk sensor  65  sensing the twenty-four projections  48  of the second disk  37  and outputting twenty-four pulse signals per revolution of the upper kneading drum  11 . That is, while the upper kneading drum  11  makes one revolution, the first and second disk sensors  63  and  65  output one and twenty-four pulse signals, respectively.  
         [0044]    The first and second disk sensors  63  and  65  include light emitting parts  63   a  and  65   a  that emit a sensing signal such as infrared rays toward the first and second disks  36  and  37 , and light receiving parts  63   b  and  65   b  that face the light emitting parts  63   a  and  65   a , respectively, across the first and second disks  36  and  37  and receive the light emitted from the light emitting parts  63   a  and  65   a , respectively.  
         [0045]    The first disk sensor  63  senses when the single projection  44  of the first disk  36  interrupts the light emitted from the light emitting part  63   a  to the light receiving part  63   b , thereby outputting one pulse signal per revolution of the upper kneading drum  11 .  
         [0046]    The second disk sensor  65  senses when the twenty-four projections  48  of the second disk  37  interrupt the light emitted from the light emitting part  65   a  to the light receiving part  65   b , thereby outputting twenty-four pulse signals per one complete turn of the upper kneading drum  11 .  
         [0047]    The rotation sensor  61  transmits the pulse signals output from the first and second disk sensors  63  and  65  to the controller  70 , and the controller  70  determines a rotation rate of the upper kneading drum  11  on the basis of the output pulse signals. Thus, the controller  70  controls the motor  26  of the drum driving part  25  to rotate the upper and lower kneading drums  11  and  13  according to the determined rotation rate thereof, thereby causing the mixing bag  7  to be properly reciprocated up and down.  
         [0048]    Thus, as shown in FIG. 5, the bread maker according to the embodiment of the present invention includes the first and second disk sensors  63  and  65  sensing the rotation of the first and second disks  36  and  37 , and the controller  70  determining whether the upper and lower kneading drums  11  and  13  are operating in a normal or abnormal state based upon the pulse signals output from the first and second disk sensors  63  and  65 .  
         [0049]    The controller  70  stores in a memory  71  the pulse widths of the pulse signals output from the first and second disk sensors  63  and  65  as the first and second disks  36  and  37  make one revolution. The controller  70  compares the pulse widths stored in the memory  71  with the pulse widths of the pulse signals output from the first and second disk sensors  63  and  65  as the first and second disks  36  and  37  make the next revolution. When there is a difference between the pulse widths stored in the memory  71  as the first and second disks  36  and  37  make one revolution and the pulse widths of the pulse signals output from the first and second disk sensors  63  and  65  as the first and second disks  36  and  37  make the next revolution, and the difference exceeds an allowable limit, the controller  70  determines that the upper and lower kneading drums  11  and  13  are operating in an abnormal state and stop the motor  26 . Also, the control panel  5  in the front of the electric component compartment  20  warns a user of the abnormal state.  
         [0050]    [0050]FIGS. 6A and 6B illustrate the pulse signals output from the first and second disk sensors  63  and  65 . As shown therein, while the upper kneading drum  11  makes one complete turn, the first and second disk sensors  63  and  65  output one and twenty-four pulse signals, respectively.  
         [0051]    In a normal state, the light receiving part  65   b  of the second disk sensor  65  outputs one pulse signal per 1 msec (millisecond). However, in an abnormal state, for example, where the mixing bag  7  separates from the lower kneading drum  13 , the upper kneading drum  11  becomes overloaded and the motor  26  cannot rotate the upper kneading drum  11  as fast as the motor  26  rotates the upper kneading drum  11  in the normal state, so that the light receiving parts  63   b  and  65   b  output pulse signals per unit of time that are greater than 1 msec. In other words, in the abnormal state, the first and second disks  36  and  37  rotate slower than in the normal state, so that in the abnormal state a pulse width is larger than in the normal state. The pulse width indicates a load applied to the motor  26 , so that the larger the pulse width, the higher the current that flows in the motor  26 , which may damage the motor  26 .  
         [0052]    The bread maker according to the embodiment of the present invention is controlled as follows. Referring to FIG. 7, first, the pulse signal due to the second disk  37  is sensed while the upper kneading drum  11  makes one revolution (S 1 ), and the memory  71  stores the rotation rate (pulse width) based upon the sensed pulse signal (S 3 ). Thereafter, the pulse signal due to the second disk  37  is sensed while the upper kneading drum  11  makes the next revolution (S 5 ). Then, the rotation rate sensed while the upper kneading drum  11  makes the next revolution is compared with the rotation rate stored in the memory  71  to determine whether a difference between the two rotation rates exceeds the allowable limit (S 7 ). When the difference exceeds the allowable limit, it is determined that the upper kneading drum  11  is operating in an abnormal state in which, for example, the mixing bag is incorrectly attached to the upper and lower kneading drums  11  and  13 , and the motor  26  is stopped (S 9 ). Finally, the control panel  5  warns a user of the abnormal state (S 11 ).  
         [0053]    In the foregoing embodiment, the first and second disks  36  and  37  are formed with the projections  44  and  48 , respectively, to sense the rotations of the upper and lower kneading drums  11  and  13 . However, the first and second disks  36  and  37  may be formed with a plurality of holes at regular intervals to sense the rotation of the upper and lower kneading drums  11  and  13 .  
         [0054]    According to the embodiment of the present invention, while the mixing bag  7  is reciprocated up and down to knead the dough, the internal components of the bread maker are prevented from damage caused by, for example, the upper and lower kneading drums rotating asynchronously, or the mixing bag separating from the upper or lower kneading drum because the mixing bag  7  tears, is incorrectly attached to the upper and lower kneading drums, etc.  
         [0055]    As described above, the embodiment of the present invention provides a bread maker and a control method thereof capable of preventing internal components of the bread maker from becoming damaged due to, for example, asynchronous rotation of the upper and lower kneading drums, an incorrect installation of a mixing bag, etc.  
         [0056]    Although an embodiment of the present invention has been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.