Abstract:
A refrigerator and a method of controlling the same. The refrigerator includes: tags attached to goods stored in a storage chamber; a reader, including a plurality of antennas having different identification distances, identifying the tags using the antennas; and a control unit detecting locations of the tags attached to goods stored in the storage chamber using the different identification distances of the antennas.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 2005-0000289, filed on Jan. 3, 2005 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 to a refrigerator, and more particularly, to a method of automatically identifying goods stored in its storage chamber to search stored positions of the identified goods. 
     2. Description of Related Art 
     Japanese Unexamined Patent Publication No. 2002-81848 discloses a method of identifying information, such as names, kinds, and stored positions, of goods stored in a storage chamber of a refrigerator. According to the method disclosed in the Japanese Unexamined Patent Publication No. 2002-81848, goods stored in the storage chamber of the refrigerator are easily identified, and the stored positions of the goods are also searched. To this end, additional antennas are mounted in storage cells of the storage chamber, respectively, such that the stored positions of the goods are searched by the respective antennas. 
     In the conventional refrigerator disclosed in Japanese Unexamined Patent Publication No. 2002-81848, at least two antennas are mounted in each of the storage cells of the storage chamber such that not only goods stored in the storage chamber are identified but also the stored positions of the goods are searched. Specifically, one antenna is mounted to each divider, by which the storage cells are divided from each other, and the other antenna is mounted to any one side of each storage cell for searching the stored positions of the goods. In other words, the at least one antennas are necessary for each storage cell as described above. Consequently, when the number of the divided storage cells is 4 as in Japanese Unexamined Patent Publication No. 2002-81848, at least eight antennas are necessary. 
     As the number of antennas increases, the number of wires used to electrically connect the antennas to each other also increases, and installation spaces for the antennas also increase. As a result, the size of the refrigerator needs to be increased, or the capacity of the storage chamber decreases. Furthermore, it is necessary to consider the installation spaces for the antennas when the design of the refrigerator is changed. Consequently, the change in design of the refrigerator is complicated, which increases the manufacturing costs of the refrigerator. 
     BRIEF SUMMARY 
     It is an aspect of the invention to mount a small number of antennas to one end surface of a storage chamber formed in a refrigerator, instead of mounting a large number of antennas to each of the inner side surfaces of several divided storage cells of the storage chamber, such that basic information of goods stored in the storage cells is identified and the stored positions of the goods are searched, thereby reducing cells that the antennas occupy, thus decreasing the size of the refrigerator or increasing the capacity of the storage chamber, and reducing the manufacturing costs of the refrigerator. 
     According to an aspect of the present invention, there is provided a refrigerator including: tags attached to goods stored in a storage chamber; a reader, including a plurality of antennas having different identification distances, identifying the tags using the antennas; and a control unit detecting locations of the tags attached to goods stored in the storage chamber using the different identification distances of the antennas. 
     According to another aspect of the present invention, there is provided a method of controlling a refrigerator having a storage chamber including a plurality of storage cells, tags attached to goods stored in the storage chamber, and a reader including a plurality of antennas having different identification distances, identifying the tags using the antennas, the method including detecting stored positions of the goods stored in the storage chamber by the different identification distances of the antennas. 
     According to another aspect of the present invention, there is provided a method of acquiring item-related data of items stored in storage cells of a refrigerator, including: acquiring, using a first antenna an identification distance of which is limited to a first storage cell, a first data set of items stored in the first storage cell and storing the first data set as first item data (M 1 ); acquiring, using a second antenna an identification distance of which is limited to the first storage cell and a second storage cell, a second data set of items stored in the first and second storage cells, removing from the second data set the first item data (M 1 ) to yield second item data (M 2 ), and storing the second item data (M 2 ); acquiring, using a third antenna an identification distance of which is limited to the first storage cell, the second storage cell, and a third storage cell, a third data set of items stored in the first through third storage cells, removing from the third data set the first item data (M 1 ) and the second item data (M 2 ) to yield third item data (M 3 ), and storing the third item data (M 3 ); and acquiring, using a fourth antenna, a fourth data set of items stored in the first storage cell, the second data cell, the third data cell, and a fourth storage cell, a fourth data set of items stored in the first, second, third, and fourth storage cells, removing from the fourth data set the first item data (M 1 ), the second item data (M 2 ), and the third item data (M 3 ) to yield fourth item data (M 4 ), and storing the fourth item data (M 4 ). The antennae are located at a surface of the refrigerator and distances between the surface and the first, second, third, and fourth storage cells respectively increase. 
     According to another aspect of the present invention, there is provided a method of acquiring item-related data of items stored in storage cells of a refrigerator, including: acquiring, using a first antenna an identification distance of which is limited to a first storage cell, a first data set of items stored in the first storage cell and storing the first data set as first item data (M 1 ); acquiring, using a second antenna an identification distance of which is limited to the first storage cell and a second storage cell, a second data set of items stored in the first and second storage cells, removing the first item data (M 1 ) from the second data set to yield second item data (M 2 ), and storing the second item data (M 2 ); and acquiring, using a third antenna an identification distance of which is limited to the first storage cell, the second storage cell, and a third storage cell, a third data set of items stored in the first through third storage cells, removing the first item data (M 2 ) and the second item data (M 2 ) from the third data set to yield third item data (M 3 ) and storing the third item data (M 3 ). The antennae are located at a surface of the refrigerator and distances between the surface and the first, second and third storage cells respectively increase. 
     Additional aspects and/or 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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a block diagram illustrating a control system of a refrigerator according to an embodiment of the present invention; 
         FIG. 2  is a view illustrating installation of antennas of the refrigerator according to an embodiment of the present invention; 
         FIG. 3  is a graph illustrating magnetic field strengths based on distances from the antennas in a radio frequency identification (RFID) system; 
         FIG. 4  is a view illustrating relations between identification distances of the antennas and searchable storage cells in the refrigerator according to an embodiment of the present invention; 
         FIG. 5  is a flow chart illustrating a method of controlling a refrigerator according to an embodiment of the present invention; and 
         FIG. 6  is a view illustrating installation of antennas of a refrigerator according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Reference will now be made in detail to 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. 
       FIG. 1  is a block diagram illustrating a control system of a refrigerator according to an embodiment of the present invention. To the input of a control unit  102  that controls operation of the refrigerator is connected a radio frequency ID (RFID) reader  104 , as shown in  FIG. 1 . The RFID reader  104  includes antennas for receiving radio frequency (RF) signals. 
     To each good  106  stored in a storage chamber of the refrigerator according to an embodiment of the present invention is attached an RFID tag  112 , which contains information, such as, by way of non-limiting examples, the name, the kind, the storage date, and the expiration date, of the good  106 . The RFID reader  104  transmits an RF signal to the RFID tag  112  and receives another RF signal from the RFID tag  112  for identifying the good  106  and obtaining the relevant information. 
     The information of the good  106  obtained from the RFID tag  112  is transmitted to the control unit  102 , which stores the information of the good  106  in a memory unit  110 . As necessary, the control unit  102  outputs the information of the good  106  to a display unit  108 , which is electrically connected to the output of the control unit  102 , such that a user confirms the information of the good  106 . The display unit  108  displays not only basic information of the good  106  stored in the storage chamber but also the current stored position of the good  106 . The stored position of the good  106  is displayed based on whether the good  106  is stored in a chilling chamber of the refrigerator or in a freezing chamber of the refrigerator, and in which storage cell the good  106  is stored when the good  106  is stored in the chilling chamber. 
       FIG. 2  is a view illustrating installation of antennas of the refrigerator according to an embodiment of the present invention. Referring to  FIGS. 1 and 2 , the refrigerator has a plurality of antennas  206   a  to  206   d , which are disposed at the inner bottom surface of a storage chamber  202  for reading data contained in an RFID tag  112  attached to a good  106  stored in the storage chamber  202  to search not only basic information of the stored good  106  but also the stored position of the stored good  106 . The antennas  206   a  to  206   d  are mounted below the inner bottom surface of the storage chamber  202  to prevent the antennas  206   a  to  206   d  from being contaminated by stored goods or moisture. 
     As shown in  FIG. 2 , the storage chamber  202  includes four storage cells  204   a  to  204   d . The antennas  206   a  to  206   d  are mounted below the inner bottom surface of the first storage cell  204   a , which is the lowest storage cell, for generating magnetic fields. The magnetic field strengths generated from the antennas  206   a  to  206   d  are different from each other, since the antennas  206   a  to  206   d  have different radiuses. As a result, the antennas  206   a  to  206   d  have different RF signal transmission and reception distances  208   a  to  208   d . The RF signal transmission and reception distance  208   a  of the first antenna  206   a , which has the smallest radius, is limited from the inner bottom surface of the first storage cell  204   a  to the inner top surface of the first storage cell  204   a . The RF signal transmission and reception distance  208   b  of the second antenna  206   b , which has a radius slightly larger than that of the first antenna  206   a , is limited from the inner bottom surface of the first storage cell  204   a  to the inner top surface of the second storage cell  204   b . The RF signal transmission and reception distance  208   c  of the third antenna  206   c , which has a radius slightly larger than that of the second antenna  206   b , is limited from the inner bottom surface of the first storage cell  204   a  to the inner top surface of the third storage cell  204   c . The RF signal transmission and reception distance  208   d  of the fourth antenna  206   d , which has the largest radius, is limited from the inner bottom surface of the first storage cell  204   a  to the inner top surface of the fourth storage cell  204   d.    
     In the refrigerator according to the present embodiment, at most one antenna is required to identify a tagged good in a storage cell. Thus, at most four antennas  206   a  to  206   d  are used to identify the goods stored in the four storage cells  204   a  to  204   d  (also used to search the locations of the stored goods). 
     The fact that the four antennas  206   a  to  206   d  have different RF signal transmission and reception distances means that the distances within which the antennas  206   a  to  206   d  can identify the RFID tag  112  are different from each other. The identification distances are determined based on the lengths of the four arrows  208   a  to  208   d  indicated in  FIG. 2 . When the antennas  206   a  to  206   d  are formed in the shape of a coil, the RF signal transmission and reception distances, i.e., the RFID tag identification distances are determined based on the radiuses of the antennas  206   a  to  206   d , which are shown in  FIG. 3 . 
       FIG. 3  is a graph illustrating magnetic field strengths based on distances from the antennas in a RFID system, which refers to FIG. 4.4 of RFID Handbook (Klaus Finkenzeller, 2004). It can be seen from  FIG. 3  that the magnetic field strengths are in reverse proportion to the radiuses R of the antennas when the distances from the antennas are below a specified value X 1 . When the distances from the antennas are above a specified value X 2 , on the other hand, the magnetic field strengths are proportional to the radiuses R of the antennas. Specifically, the difference in radius of the antennas  206   a  to  206   d  of  FIG. 2  causes the difference in magnetic field strength, which means that the RFID tag identification distances of the antennas  206   a  to  206   d  may be changed to differ from each other. But, the magnetic field strengths are in proportion to the radiuses R of the antennas when the distances from the antennas are above the specified value X 2 . Consequently, the distances between the position where the antennas  206   a  to  206   d  are mounted and the inner bottom surface of the first storage cell  204   a  is above at least X 2  in  FIG. 2 . 
       FIG. 4  is a view illustrating relations between identification distances of the antennas and searchable storage cells in the refrigerator according to the present embodiment. Refers to  FIGS. 2 and 4 , the first antenna  206   a  searches only the first storage cell  204   a ; the second antenna  206   a  searches the first and second storage cells  204   a  and  204   b ; the third antenna  206   c  searches the first to third storage cells  204   a  to  204   c ; and the fourth antenna  206   d  searches the first to fourth storage cells  204   a  to  204   d.    
     It can be seen from  FIG. 4  that, although the identification distances of the four antennas  206   a  to  206   d  are different from each other, the identification distances are partially overlapped with each other, and therefore, the search results are also overlapped. For this reason, it is necessary to provide a control method for extracting information of the stored goods for each storage cell from the search results of the goods stored in the storage chamber  202 , which is illustrated in  FIG. 5 . 
       FIG. 5  is a flowchart illustrating a method of controlling a refrigerator according to an embodiment of the present invention. The method can be performed by the respective control system and the refrigerator of  FIGS. 1 and 2 , and is, for ease of explanation, described in conjunction with those figures. However, it is to be understood that other apparatuses may perform the method. 
     Referring to  FIGS. 1 ,  2 , and  5 , a search is performed first using the first antenna  206   a  to collect first stored good-related data M 1 , and the collected first stored good-related data M 1  is stored in the memory unit  110  (operation  502 ). The identification distance of the first antenna  206   a  is limited to the first storage cell  204   a . Consequently, the first stored good-related data M 1  corresponds to information of the goods stored in the first storage cell  204   a.    
     Next, another search is performed using the second antenna  206   b  to collect second stored good-related data M 2 , and the collected second stored good-related data M 2  is stored in the memory unit  110  (operation  504 ). In this case, the second stored good-related data M 2  corresponds to information of the goods stored in the first and second storage cells  204   a  and  204   b . For this reason, the first stored good-related data M 1  is removed from the second stored good-related data M 2  to extract information of the goods stored only in the second storage cell  204   b , and then the second stored good-related data M 2  containing no first stored good-related data M 1  is stored in the memory unit  110  (M 2 =M 2 −M 1 ). 
     After that, another search is performed using the third antenna  206   c  to collect third stored good-related data M 3 , and the collected third stored good-related data M 3  is stored in the memory unit  110  (operation  506 ). In this case, the third stored good-related data M 3  corresponds to information of the goods stored in the first to third storage cells  204   a  to  204   c . For this reason, the first and second stored good-related data M 1  and M 2  are removed from the third stored good-related data M 3  to extract information of the goods stored only in the third storage cell  204   c , and then the third stored good-related data M 3  containing no first and second stored good-related data M 1  and M 2  is stored in the memory unit  110  (M 3 =M 3 −(M 2 +M 1 )). Here, M 2  is second stored good-related data containing no first stored good-related data M 1 . 
     Finally, another search is performed using the fourth antenna  206   d  to collect fourth stored good-related data M 4 , and the collected fourth stored good-related data M 4  is stored in the memory unit  110  (operation  508 ). In this case, the fourth stored good-related data M 4  corresponds to information of the goods stored in the first to fourth storage cells  204   a  to  204   d . For this reason, the first to third stored good-related data M 1  to M 3  are removed from the fourth stored good-related data M 4  to extract information of the goods stored only in the fourth storage cell  204   d , and then the fourth stored good-related data M 4  containing no first to third stored good-related data M 1  to M 3  is stored in the memory unit  110  (M 4 =M 4 −(M 3 +M 2 +M 1 )). Here, M 3  is third stored good-related data containing no first and second stored good-related data M 1  and M 2 , and M 2  is second stored good-related data containing no first stored good-related data M 1 . 
     The first to fourth stored good-related data M 1  to M 4  stored in the memory unit  110  through the above-described process correspond to information of the goods stored in the first to fourth storage cells  204   a  to  204   d , respectively. Consequently, the stored positions of the goods stored in the storage chamber  202  can be identified by storage cell through the use of the information. 
     In the above-described embodiment of the present invention shown in  FIGS. 1-5 , the antennas  206   a  to  206   d  are sequentially operated to search the storage cells  204   a  to  204   d , although the antennas  206   a  to  206   d  may be simultaneously operated, and then the difference between data collected by the respective antennas  206   a  to  206   d  may be extracted to obtain stored good-related data for each storage cell. 
       FIG. 6  is a view illustrating installation of antennas of a refrigerator according to another embodiment of the present invention. As shown in  FIG. 6 , antennas  606   a  to  606   d  are preferably mounted above the inner top surface of a storage chamber  602  of the refrigerator. As described above, magnetic field strengths are in proportion to the radiuses of the antennas when the distances from the antennas are above the specified value X 2 . Consequently, the distances between the position where the antennas  606   a  to  606   d  are mounted and the inner top surface of the first storage cell  604   a  is above at least X 2  in  FIG. 6 . 
     As apparent from the above description, a small number of antennas are mounted to one end surface of the storage chamber formed in the refrigerator, instead of mounting a large number of antennas to each of the inner side surfaces of several divided storage cells of the storage chamber, such that basic information of goods stored in the storage cells is identified and the stored positions of the goods are searched. Consequently, the above-described embodiments of the present invention have the effect of reducing cells that the antennas occupy, thus decreasing the size of the refrigerator or increasing the capacity of the storage chamber, and reducing the manufacturing costs of the refrigerator. 
     Although a few embodiments of the present invention have been shown and described, the present invention is not limited to the described embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.