Abstract:
The present invention discloses a reader coil antenna, and a non-contacting type card identification system using the same for increasing the sensing region of the card reader system. The reader coil antenna includes an outer coil for forming a predetermined loop, and which forms a magnetic field by receiving a current, along with at least one inner coil disposed inside the loop of the outer coil, for generating a constructive interference in a direction of the magnetic field of the outer coil. The card identification system, of the present invention, includes a reader coil antenna which forms a magnetic field due to a signal applied to flow in a single direction, a card reader for transmitting an operating signal through the reader coil antenna, and decoding an input signal from a non-contacting type card, and a control unit for deciding identification of the non-contacting type card according to the decoded signal.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a reader coil antenna, and a non-contacting type card identification system using the same, and more particularly to an improved reader coil antenna which can form a magnetic field, transmit an operating frequency, and receive a frequency from a non-contacting type card in order to decode data of the non-contacting type card, and a noncontacting type card identification system using the same.  
           [0003]    2. Description of the Related Art  
           [0004]    Both a contacting type magnetic card having a magnetic strip portion which is rubbed for identification, and a non-contacting type card which transmits/receives data by frequency in a magnetic field space have been generally used as means for making payment. Examples of magnetic cards are credit cards and pre-paid telephone cards, while examples of the non-contacting type card are pre-paid transportation cards, and non-contacting type subway credit cards.  
           [0005]    [0005]FIG. 1 is a block diagram illustrating a conventional non-contacting type card identification system. Referring to FIG. 1, the conventional non-contacting type card identification system  10  includes an antenna system  16 , a card reader  18  and a control unit  20 .  
           [0006]    The card reader  18  generates a current to sense a non-contacting type card  14 , and transmits a magnetic field formed by the current through the antenna system  16 .  
           [0007]    The non-contacting type card  14  manually charges a battery by the transmitted magnetic field, and transmits a signal including an internally-stored data to the antenna system  16 .  
           [0008]    The signal received in the antenna system  16  is output to the control unit  20  through the card reader  18 .  
           [0009]    The signal received in the control unit  20  is compared with master security information (not shown) stored in the control unit  20  to decide card identification, and is transmitted through the antenna system  16 .  
           [0010]    Further, the antenna system  16  includes a reader coil antenna, and generates the magnetic field by the applied current to the reader coil antenna and receives the signal from the non-contacting type card  14 .  
           [0011]    [0011]FIG. 2 is a perspective diagram illustrating a conventional reader coil antenna. As shown therein, the conventional reader coil antenna includes a driving loop antenna  22 , double loop antennas  32 ,  34  and a non-magnetic conductive material  26 .  
           [0012]    Here, the double loop antennas  32 ,  34  are connected to each other in a cross-over type connection  36 . In addition, the non-magnetic conductive material  26  contains aluminum, silver, copper, brass or gold to induce the magnetic field of the driving loop antenna  22  by providing a shield against an eddy current. A driving current for driving the non-contacting type card  14  is applied to terminals  28 ,  30  connected to the card reader  18 . The magnetic field is generated in the driving loop antenna  22  due to the applied current. Here, an induced current is generated in the double loop antennas  32 ,  34  by the driving loop antenna  22 . The induced current has a phase difference of 180° from a direction of the current flowing through the driving loop antenna  22 .  
           [0013]    The double loop antennas  32 ,  34  are adhered to the surface of the non-magnetic conductive material  26 . Accordingly, the magnetic field is generated on the front surface of the antenna system  16  where the non-contacting type card  14  is positioned, but induced and absorbed on the rear surface thereof.  
           [0014]    In the above-described reader coil antenna, the driving loop antenna  22  and the double loop antennas  32 ,  34  have the opposite current direction. It is thus difficult to increase a reading distance which is the data recognition distance between the antenna system  16  and the non-contacting type card  14 . Moreover, the non-magnetic conductive material  26  induces and absorbs the magnetic field, thus reducing strength of the magnetic field. As a result, the reading distance due to the magnetic field is further shortened.  
         SUMMARY OF THE INVENTION  
         [0015]    Accordingly, an object of the present invention is to provide a reader coil antenna which can increase the reading distance, where a non-contacting type card is read, due to strength of an internal magnetic field, and a non-contacting type card identification system using the same.  
           [0016]    In one aspect of the present invention, a reader coil antenna of a non-contacting type card identification system includes: an outer coil forming a predetermined loop, and forming a magnetic field by receiving a current; and at least one inner coil disposed inside the loop of the outer coil, for generating a constructive interference in a direction of the magnetic field of the outer coil by receiving a current.  
           [0017]    In another aspect of the present invention, a non-contacting type card identification system using a reader coil antenna includes: the reader coil antenna for forming a magnetic field due to a signal applied to flow in an identical direction; a card reader for transmitting an operating signal through the reader coil antenna, and decoding an input signal from a non-contacting type card; and a control unit for deciding identification of the non-contacting type card according to the decoded signal.  
           [0018]    According to the present invention, a sensing region of the center portion of the coil is increased due to the reader coil antenna provided with the identical direction current. In addition, strength of the magnetic field is increased near the center portion of the coil, by inserting a non-conductive magnetic material into the inner coil. As a result, the sensing region is increased, communication reliability is improved, and a dead zone is reduced. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:  
         [0020]    [0020]FIG. 1 is a block diagram illustrating a conventional non-contacting type card identification system;  
         [0021]    [0021]FIG. 2 is a perspective diagram illustrating a reader coil antenna in FIG. 1;  
         [0022]    [0022]FIG. 3 is a top diagram illustrating a reader coil antenna in accordance with a first embodiment of the present invention;  
         [0023]    [0023]FIG. 4 is a cross-sectional diagram illustrating the reader coil antenna in FIG. 3;  
         [0024]    [0024]FIG. 5 is a cross-sectional diagram illustrating a reader coil antenna in accordance with a second embodiment of the present invention;  
         [0025]    [0025]FIG. 6 is a cross-sectional diagram illustrating a reader coil antenna in accordance with a third embodiment of the present invention;  
         [0026]    [0026]FIG. 7 is a cross-sectional diagram illustrating a reader coil antenna in accordance with a fourth embodiment of the present invention;  
         [0027]    [0027]FIG. 8 is a graph showing strength of a magnetic field according to a coil diameter in FIGS. 3 and 7; and  
         [0028]    [0028]FIG. 9 is a block diagram illustrating a non-contacting type card identification system using the reader coil antenna in FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]    A reader coil antenna, and a non-contacting type card identification system using the same in accordance with the present invention will now be described with reference to the accompanying drawings.  
         [0030]    [0030]FIG. 3 is a top diagram illustrating a reader coil antenna in accordance with a first embodiment of the present invention, and FIG. 4 is a cross-sectional diagram illustrating the reader coil antenna in FIG. 3. The reader coil antenna includes an outer coil  120  and an inner coil  140  for forming a magnetic field due to an applied current.  
         [0031]    Here, the inner coil  140  is disposed inside the outer coil  120 . The outer coil  120  and the inner coil  140  are incorporated into one coil. In addition, the outer coil  120  and the inner coil  140  are respectively connected to terminals  160 ,  180  which are signal input/output paths. One line of the terminals  160 ,  180  is used as an input line, and the other line is used as a ground line. In this embodiment, the outer terminal  160  connected to the outer coil  120  is used as the input line of signals, and the inner terminal  180  connected to the inner coil  140  is used as the ground line.  
         [0032]    The outer coil  120  and the inner coil  140  are mounted on a printed circuit board  50  to prevent movement.  
         [0033]    When a driving current is applied to the outer terminal  160 , the identical direction current flows through the outer coil  120  and the inner coil  140 . Accordingly, a magnetic field is generated near the coil. Here, the magnetic field is formed in a single direction, and in a space surrounded by the inner coil  140 , which adds strength to the magnetic field in a vertical direction (with respect to the surface of the printed circuit board  50 , on which the coils are mounted).  
         [0034]    The more the outer coil  120  is separated from the inner coil  140 , the more the strength of the magnetic field  140  is increased in the inner coil  140 . However, when the interval between the outer coil  120  and the inner coil  140  reaches a predetermined value, namely where a diameter of the inner coil  140  is excessively small, the strength of the magnetic field of the inner coil  140  is reduced.  
         [0035]    Preferably, the coils  120 ,  140  are a made from thin films plated with copper, and are a few tens μm in thickness.  
         [0036]    The interval between the outer coil  120  and the inner coil  140  is preferably an optimal distance decided by experiments. Generally, the diameter of the coils  120 ,  140  ranges from 30 to 40 μm, and the interval between the outer coil  120  and the inner coil  140  ranges from 20 to 30 mm. Preferably, when the outer diameter of the coil  120  is 35 μm, and the inner diameter of the inner coil  140  is 25 mm, the maximum strength of the magnetic field is obtained in the inner coil  140  in a vertical direction.  
         [0037]    [0037]FIG. 5 is a cross-sectional diagram illustrating a reader coil antenna in accordance with a second embodiment of the present invention. Here, identical units to the first embodiment are provided with the same reference numerals. The reader coil antenna includes an outer coil  120 , a first inner coil  140  and a second inner coil  150 . When the two inner coils  140 ,  150  are employed, the magnetic field generated in the second inner coil  150  is stronger than the magnetic field generated in the inner coil  140  of the first embodiment. Accordingly, the inner coil may be provided in a multiple number, as shown in FIG. 5.  
         [0038]    [0038]FIG. 6 is a cross-sectional diagram illustrating a reader coil antenna in accordance with a third embodiment of the present invention. In the reader coil antenna, a magnetic inducing layer  220  consisting of a non-conductive magnetic material is plated on the rear surface of a printed circuit board  50  where coils  120 ,  140  are adhered. The non-conductive magnetic material does not have electric conductivity, and has magnetism when positioned in a magnetic field space.  
         [0039]    According to the present invention, the magnetic field exists on the rear surface of the printed circuit board  50 . The magnetic inducing layer  220  induces a direction of the magnetic field on the rear surface to the printed circuit board  50 . In this embodiment, the induced magnetic field is combined with the magnetic field of a coil direction, to generate a constructive phenomenon. It is thus possible to increase a sensing region due to the current identically applied to the coils, and to reduce discharge of the magnetic field to the rear surface of the printed circuit board  50 .  
         [0040]    Induction of the magnetic field is dependent upon a thickness of the magnetic inducing layer  220 . Preferably, when the thickness of the printed circuit board  50  ranges from 0.3 to 0.9 mm, the thickness of the magnetic inducing layer  220  ranges from 1 to 3 mm.  
         [0041]    In addition, the magnetic inducing layer  220  may be screen-printed on the rear surface of the printed circuit board  50 .  
         [0042]    [0042]FIG. 7 is a cross-sectional diagram illustrating a reader coil antenna in accordance with a fourth embodiment of the present invention. The third and fourth embodiments of the present invention use the same reference numerals. A groove  210  is formed on a printed circuit board  50 , in an internal region  230  created by the inner coil  140 . A magnetic inducing layer  220   a  is correspondingly inserted into the groove  210 , and adhered to the rear surface of the printed circuit board  50 .  
         [0043]    The magnetic inducing layer  220  adhered to the rear surface of the printed circuit board  50  is operated as in the third embodiment of the present invention.  
         [0044]    The magnetic inducing layer  220   a  inserted in from the inner coil  140 , in the internal region  230 , forms a magnetic field induced in the same direction as by the magnetic inducing layer  220  adhered to the rear surface of the printed circuit board  50 , which is in a vertical direction to the coil surface, and maintains a maximum magnitude of a vertical magnetic flux passing the non-contacting type card. Therefore, the vertical magnetic flux is increased in the inner coil  140 , thus reinforcing the strength of the internal magnetic field. In addition, the magnetic inducing layer  220   a  may be coated on the surface of the printed circuit board  50 , instead of forming the groove  210 .  
         [0045]    Further, a thickness of the magnetic inducing layer  220   a  correspondingly inserted into the groove  210  of the printed circuit board  50   140  is almost identical to a thickness of the printed circuit board  50 .  
         [0046]    [0046]FIG. 8 is a graph showing the strength of the magnetic field according generated by the embodiments shown in FIGS. 3 and 7. Referring to FIG. 8, a thin line  100  denotes the strength of the magnetic field generated by the embodiment shown in FIG. 3, and a thick line  200  denotes the strength of the magnetic field generated by the embodiment shown in FIG. 7.  
         [0047]    In the thin line  100 , the strength of the magnetic field is smaller in the center portion than the coil position. In the thick line  200 , the strength of the magnetic field is almost identical in the coil position, but changes at the center portion where the magnetic inducing layer  220   a  is inserted. As shown, the strength of the magnetic field is increased in the coil center portion due to the magnetic inducing layer  220   a.    
         [0048]    [0048]FIG. 9 is a block diagram illustrating a non-contacting type card identification system using the reader coil antenna shown in FIG. 3. The non-contacting type card identification system includes a reader coil antenna  110 , a card reader  330  and a control unit  350 . Preferably, the non-contacting type card identification system further includes a matching circuit  310  for controlling input/output signals of the reader coil antenna  110  and the card reader  330 .  
         [0049]    Reference numeral  410  denotes a sensing region by the reader coil antenna  110 , and  430  denotes a non-contacting type card.  
         [0050]    The card reader  330  transmits an operating frequency including power and a signal through the reader coil antenna  110 . In this example, the operating frequency is 13.56 MHz.  
         [0051]    The operating frequency outputted from the card reader  330  through the matching circuit  310  generates a magnetic field in the reader coil antenna  110 . At this time, the magnetic field is weak between the coils  120 ,  140  due to a destructive interference, but strong near the coils  120 ,  140  due to a constructive interference. Thus, the sensing region formed by the identical operating frequency is increased.  
         [0052]    An inducing electromotive force is accumulated in the non-contacting type card  430  due to the discharged magnetic field, and then discharged to the reader coil antenna  110  with the stored information.  
         [0053]    The received signal is input to the card reader  330  through the matching circuit  310 . The card reader  330  reads, amplifies, filters and decodes the data. The control unit  350  decides identification according to the decoded signal.  
         [0054]    According to the present invention, the sensing region of the center portion of the coil is increased due to the reader coil antenna provided with the identical (or single) direction current. In addition, the non-conductive magnetic material is adhered to the rear surface of the printed circuit board, and thus the magnetic field is not generated thereon. It is thus possible to control discharge of the magnetic field in an unwanted direction. Moreover, the strength of the magnetic field is increased near the center portion of the coil, by inserting the non-conductive magnetic material in from the inner coil, as shown in FIG. 7. As a result, the sensing region for the system is increased, communication reliability is improved, and the size of a dead zone is reduced.  
         [0055]    The coils shown and discussed above are formed in a circular shape, but may be formed in various shapes to apply the identical direction current to the outer coil and the inner coil.  
         [0056]    Further, in the embodiments shown and discussed above, the outer coil and the inner coil have the identical center portion, or a common center point. However, it should be noted that as long as the inner coil is positioned inside of the outer coil, the outer coil and the inner coil may have different center portions, or center points.  
         [0057]    In addition, in the above discussed embodiments, the coils are mounted on the printed circuit board. However, the printed circuit board may not be required if the coil position and the current direction are made and used in accordance with the present invention.  
         [0058]    Although the preferred embodiments of the present invention have been described, it is understood that the present invention should not be limited to these preferred embodiments, and that various changes and modifications can be made by one skilled in the art within the spirit and scope of the present invention as hereinafter claimed.