Abstract:
A game chip transmits information in response to an inquiry from a reader/writer. The game chip comprises an IC device, an antenna coil unit, a first ring and a second ring. The IC device constitutes an electromagnetic induction coupling circuit with the reader/writer and stores information. The antenna coil unit is connected to the IC device and generates an induced current by a magnetic flux emitted from the reader/writer to supply power to the IC device when the inquiry is received. The first ring induces the magnetic flux emitted from the reader/writer in one of directions of moving away from and approaching the reader/writer. The second ring induces the magnetic flux induced by the first ring in the other of the directions of moving away from and approaching the reader/writer.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims benefit of priority under 35 U.S.C. §119 to Japanese Patent Application No. 2004-367241, filed on Dec. 20, 2004 and No. 2005-006076 filed on Jan. 13, 2005, the entire contents of which are incorporated by reference herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a game chip, and more specifically to a game chip capable of being recognized by a reading device such as a reader/writer.  
         [0004]     2. Description of the Related Art  
         [0005]     There has conventionally been available a gaming machine that imitates a game in which a game table is employed and allows a player to make a bet without using real betting chips. The player inputs a betting target and the number of betting chips to the gaming machine by using buttons disposed on a control panel. However, the gaming machine has no function of permitting the player to directly put the betting chips on a game table, resulting in an impossibility of giving realistic sensation to the player during the game.  
         [0006]     In order to solve the above problem, a gaming machine has been developed newly. The gaming machine enables a player to directly put betting chips in a predetermined area of the game table to make a bet. A roulette game, a card game (e.g. poker or black jack) and the like are cited as games installed in this gaming machine.  
         [0007]     Conventional game chips (betting chips) are disclosed in Japanese Patent Application Laid-Open No. 2003-196634, No. 2003-85504 and No. 2004-21648. Each of these game chips incorporates an IC tag therein. The gaming machine recognizes the game chips and then reads the number of game chips with a reader/writer.  
         [0008]     Generally, in a betting process, a player bets the desired number of game chips on a betting target (e.g. specific numeral, red/black, odd number/even number, or the like). More specifically, the player puts the desired number of game chips in a predetermined area (e.g. area to which numerals  1  to  36  each is assigned, area to which red or black is assigned, area to which an odd number or an even number is assigned, or the like) of the game table. In this case, the player must put the game chips in the predetermined area so that the reader/writer surely reads information stored in the IC tags of the game chips. When the number of game chips is large, the player must pile the game chips in a layer shape to put the game chips in the predetermined area.  
         [0009]     However, piling the game chips in the layer shape causes an increase in distance between the reader/writer and the game chip of an upper layer. Therefore, when the reader/writer recognizes the game chips by an electromagnetic induction method, fluxes of magnetic lines (magnetic fluxes) emitted from the reader/writer are sufficiently diffused around before the magnetic fluxes reach the game chip of the upper layer. This causes a considerable reduction in the number of magnetic fluxes capable of reaching the game chip of the upper layer. In consequence, there is a possibility that the IC tag incorporated in the game chip of the upper layer will not reply to an inquiry from the reader/writer.  
         [0010]     In order to enable the reader-writer to surely recognize the game chip of the upper layer by the electromagnetic induction method, the number of magnetic fluxes emitted from the reader/writer may be increased. However, the increase in the number of magnetic fluxes emitted from the reader/writer creates a problem that another game chip, to be recognized by another reader/writer, put in an area adjacent to the predetermined area is recognized by the reader/writer because of the diffused-around magnetic fluxes.  
       SUMMARY OF THE INVENTION  
       [0011]     It is an object of the present invention to provide game chips which enable a reading device to recognize a game chip of an upper layer in a state of piling the game chips in a layer shape.  
         [0012]     It is another object of the present invention to provide game chips which can prevent a reading device from recognizing another game chip located in one of radial directions of the game chips in a state of piling the game chips in a layer shape when the number of magnetic fluxes emitted from the reading device is increased.  
         [0013]     In order to achieve the object, the present invention provides a game chip configured to transmit information in response to an inquiry from a reading device, comprising: a circuit unit configured to store the information and constitute an electromagnetic induction coupling circuit with the reading device; an antenna unit connected to the circuit unit and configured to generate an induced current by a magnetic flux emitted from the reading device to supply power to the circuit unit when the inquiry is received, and to emit a magnetic flux carrying the information to the reading device when the information is transmitted; a first magnetic flux induction unit configured to induce the magnetic flux emitted from the reading device in one of directions of moving away from and approaching the reading device; and a second magnetic flux induction unit configured to induce the magnetic flux induced by the first magnetic flux induction unit in the other of the directions of moving away from and approaching the reading device.  
         [0014]     According to the present invention, in a state where the game chips are stacked in layers, magnetic fluxes are guided to the first or second magnetic flux induction unit of each game chip to reach a game chip located in an upper layer without being diffused around. Accordingly, without greatly reducing the number of magnetic fluxes, the magnetic fluxes can reach the game chip located in the upper layer.  
         [0015]     Moreover, in the state where the game chips are stacked in layers, when the magnetic fluxes cross the game chip located in the upper layer to be discharged into an atmosphere, the magnetic fluxes are guided to the first or second magnetic flux induction unit of each game chip without being diffused around, to return to its radiation source (reading device). Accordingly, even if the number of magnetic fluxes emitted from the reading device is increased so that the reading device surely recognizes the game chip of the upper layer by an electromagnetic induction method, it is possible to prevent the reading device from recognizing another game chip, to be read by another reading device, located in one of radial directions of the game chips 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a perspective diagram of a gaming machine according to an embodiment of the present invention.  
         [0017]      FIG. 2  is a functional block diagram of the gaming machine according to the embodiment of the present invention.  
         [0018]      FIG. 3A  is a perspective diagram of a game chip according to the embodiment of the present invention.  
         [0019]      FIG. 3B  is a sectional diagram along the line IIIB-IIIB of  FIG. 3A .  
         [0020]      FIG. 3C  is a sectional diagram along the line IIIC-IIIC of  FIG. 3B .  
         [0021]      FIG. 4  is a diagram showing magnetic fluxes emitted from a reader/writer when the reader/writer reads information from one game chip according to the embodiment of the present invention.  
         [0022]      FIG. 5  is a diagram showing magnetic fluxes emitted from the reader/writer when the reader/writer reads information from a plurality of game chips according to the embodiment of the present invention;  
         [0023]      FIG. 6A  is a perspective diagram of a game chip according to a modified example of the embodiment of the present invention.  
         [0024]      FIG. 6B  is a sectional diagram along the line VIB-VIB of  FIG. 6A .  
         [0025]      FIG. 6C  is a sectional diagram alone the line VIC-VIC of  FIG. 6B .  
         [0026]      FIG. 7  is a diagram showing magnetic fluxes emitted from the reader/writer when the reader/writer reads information from one game chip according to the modified example of the embodiment of the present invention.  
         [0027]      FIG. 8  is a diagram showing magnetic fluxes emitted from the reader/writher when the reader/writer reads information from a plurality of game chips according to the modified example of the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     Hereinafter, the preferred embodiments of the present invention will be described with reference to FIGS.  1  to  8 .  
         [0000]     (1. Gaming Machine)  
         [0029]     A gaming machine  100  is an apparatus which enables a player, to play a roulette game. As shown in  FIGS. 1 and 2 , the gaming machine  100  comprises a main body  101 , a wheel  102 , a layout  103 , a ball  104 , a plurality of game chips  105 , a main control device  201  and a plurality of readers/writers  202 .  
         [0030]     The main body  101  is formed in to a table shape. The wheel  102  has pockets corresponding to numerals “0” to “36” colored red or black, and is disposed on an upper surface of the main body  101 . The layout  103  has betting targets (betting areas) corresponding to numerals/colors of “1→18”, “19→36”, “1→12”, “13→24”, “25→36”, “0” to “36”, “red”, “black”, “odd number” and “even number”, and is disposed on the upper surface of the main body  101 . The ball  104  is stored in the wheel  102 . The game chip  105  is a tool which is employed to indicate a betting target and an amount of values (e.g. cash, credits or points) bet on the betting target. The game chip  105  is put at one of the betting targets arrayed in the layout  103  in a betting process of the roulette game.  
         [0031]     The main control device  201  controls a progress of the roulette game, and is arranged in the main body  101 . The reader/writer  202  reads information (ID information in this embodiment) stored in an IC device of the game chip  105 , and is arranged in the main body  101  so as to be opposed to one of the betting targets of the layout  103 . The reader/writer  202  reads information stored in the IC device of the game chip  105  put on a related betting target, and transmits the read information to the main control device  201 . The ID information is information for identifying an attribute of the game chip  105 . Based on the ID information, the main control device  201  recognizes a player who owns the game chip  105  and a value of the game chip  105  corresponding to the ID information.  
         [0032]     The reader/writer  202  does not need to have a function of both reading and writing, but only needs to have at least a function of reading information stored in the IC device of the game chip  105 . The information stored in the IC device of the game chip  105  is not limited to the ID information. Any information can be employed as long as it enables the main control device  201  to recognize the player who owns the game chip  105  and the value of the game chip  105 . For example, player ID information and chip value information (value of 1 coin, value of 10 coins, value of 100 coins or the like) may be separately stored in the game chip. By storing the player ID information, it is possible to prevent pretense of being a player. It is noted that terminal ID information may be substituted for the player ID information when a player terminal is employed in the roulette game.  
         [0033]     In the betting process of the roulette game, the player predicts a pocket of the wheel  102  in which the rotating ball  104  will be held, and puts one or more game chips  105  on one or more betting targets arrayed in the layout  103  based on a numeral/color corresponding to the predicted pocket. After one or more game chips  105  have been put in the layout  103 , each reader/writer  202  reads information from the IC device of each game chip  105 , and transmits the read information to the main control device  201 . The main control device  201  recognizes one or more betting targets indicated by the player and a value of each game chip  105  and the number of game chips  105  put on each betting target by the player based on the received information.  
         [0034]     Upon recognition that the player has made a bet, the main control device  201  rotates the ball  104  in the wheel  102 . Then, the main control device  201  detects a pocket which has held the ball  104  via a sensor (not shown) disposed in the wheel  102  to determine whether or not the pocket predicted by the player matches the pocket holding the ball  104 . If matched, the main control device  201  adds a dividend to player&#39;s game account stored therein in accordance with odds and the value of each game chip  105  and the number of game chips  105  put on the winning betting target, and displays the dividend and a total amount on a payout display (not shown).  
         [0000]     (2-1. Game Chip)  
         [0035]     As shown in  FIGS. 3A  to  3 C, the game chip  105  comprises a main body  301 , an IC device (circuit unit)  302 , an antenna coil unit (antenna unit)  303 , a first ring (first magnetic flux induction unit)  304 , a second ring (second magnetic flux induction unit)  305  and a substrate  306 . The main body  301  is made of a resin or the like, and is provided with an annular upper plate, a disk lower plate and a cylindrical side plate. The main body  301  houses the IC device  302 , the antenna coil unit  303  and the substrate  306 . The substrate  306  is formed into a disk shape, and arranged on an upper surface of the lower plate of the main body  301 . The substrate  306  is coaxial to the main body  301 .  
         [0036]     The IC device  302  is formed into a columned shape, and arranged in a center of the substrate  306  to be coaxial to the substrate  306 . The IC device  302  is an electronic component for executing a processing function, a storing function and an input/output control function, and transmits information stored therein to the reader/writer  202  in response to an inquiry from the reader/writer  202 .  
         [0037]     The antenna coil unit  303  is formed into an annular shape, and arranged in a peripheral edge of the substrate  306  so as to surround the IC device  302  to be coaxial to the IC device  302 . The antenna coil unit  303  is connected to the IC device  302  to support transfer of information between the reader/writer  202  and the IC device  302 . The IC device  302  does not need any battery because the IC device  302  transmits/receives information by using a current induced at the antennal coil unit  303  by fluxes of magnetic lines (magnetic fluxes) emitted from the reader/writer  202 .  
         [0038]     The first ring  304  is formed into an cylindrical shape, and fitted to the main body  301  so as to surround an outer peripheral surface of the main body  301  to be coaxial to the main body  301 . The first ring  304  is made of a diamagnetic or perfect diamagnetic material. The first ring  304  cancels magnetic fluxes diffused around to guide the magnetic fluxes to a hollow part thereof in which the main body  301  is arranged.  
         [0039]     The second ring  305  is formed into a cylindrical shape, and is fitted to the first ring  304  so as to surround an outer peripheral surface of the first ring  304  to be coaxial to the first ring  304 . The second ring  305  is made of a material of high relative magnetic permeability (e.g. iron or ferrite). Generally, a magnetic flux has a nature of gathering on a material of high relative magnetic permeability. Accordingly, the second ring  305  captures magnetic fluxes to prevent the magnetic fluxes from leaking to the outside of the game chip  105 . By arranging the second ring  305  in a peripheral border of the game chip  105 , the reader/writer  202  does not read information of another game chip, to be read by another reader/writer, arranged in an area adjacent to the predetermined area. The relative magnetic permeability of the second ring  305  only needs to be higher than that of the main body  301  which has housed the IC device  302  and the antennal coil unit  303 . The second ring  305  has a height h almost equal to that of the first ring  304 .  
         [0040]     The shapes of the first and second rings  304  and  305  are not limited to the cylindrical shapes. Any shapes are allowed as long as the first and second rings  304  and  305  come into contact with parts of adjacent first and second rings  304  and  305  in an up-and-down direction, respectively, in a state where the game chips  105  are stacked in layers. Spaces may be formed between the main body  301  and the first ring  304  and/or between the first and second rings  304  and  305 .  
         [0000]     (3-1. Information Reading)  
         [0041]     First, a mechanism by which the reader/writer  202  reads information of one game chip  105  will be described.  
         [0042]     The reader/writer  202  generates a carrier wave (AC signal) belonging to a 135 kHz band or a 13.56 MHz band, and modulates the carrier wave and amplifies power based on a base band signal corresponding to transmit data. Then, upon supplying of the carrier wave to an antenna (loop coil)  202   a  of the reader/writer  202 , magnetic fluxes  401  are emitted from a hollow part of the antenna  202   a.    
         [0043]     At the antenna  202   a,  when a current flows in a counterclockwise direction viewed from the upper surface of the main body  101 , the magnetic fluxes  401  are radiated upward with respect to the antenna  202   a  by a corkscrew rule. The radiated magnetic fluxes  401  are guided by the first ring  304  from the lower side of the first ring  304  to the hollow part of the first ring  304  without being diffused around, to be discharged into an atmosphere. The discharged magnetic fluxes  401  are captured by the second ring  305  to be guided to the hollow part of the antenna  202   a  of the reader/writer  202  (see  FIG. 4 ).  
         [0044]     At the antenna  202   a,  when a current flows in a clockwise direction viewed from the upper surface of the main body  101 , the magnetic fluxes  401  are radiated downward with respect to the antenna  202   a  by a corkscrew rule. The radiated magnetic fluxes  401  are captured by the second ring  305  to be discharged into an atmosphere. The discharged magnetic fluxes  401  are guided by the first ring  304  from the upper side of the first ring  304  to the hollow part of the first ring  304  without being diffused around, to return to the hollow part of the antenna  202   a  of the reader/writer  202 .  
         [0045]     When the magnetic fluxes  401  cross the hollow part of the antenna coil unit  303 , a current is induced at the antenna coil unit  303  by electromagnetic induction, and then power is supplied to the IC device  302 . Thus, the game chip  105  and the reader/writer  202  constitute an electromagnetic induction coupling circuit. When the induced current is supplied to the IC device  302 , the game chip  105  transmits information stored in the IC device  302  to the reader/writer  202  by using load modulation.  
         [0046]     Next, a mechanism by which the reader/writer  202  reads information of a plurality of game chips  105  (five game chips in this embodiment) stacked in layers will be described.  
         [0047]     The reader/writer  202  generates a carrier wave (AC signal) belonging to a 135 kHz band or a 13.56 MHz band, and modulates the carrier wave and amplifies power based on a base band signal corresponding to transmit data. Then, upon supplying of the carrier wave to the antenna (loop coil)  202   a  of the reader/writer  202 , the magnetic fluxes  401  are emitted from the hollow part of the antenna  202   a.    
         [0048]     At the antenna  202   a,  when a current flows in a counterclockwise direction viewed from the upper surface of the main body  101 , the magnetic fluxes  401  are radiated upward with respect to the antenna  202   a  by a corkscrew rule (see  FIG. 5 ). The radiated magnetic fluxes  401  are guided by a first ring  304   1  of a game chip  105   1  located in a lower layer from a lower side of the first ring  304   1  to a hollow part of the first ring  304   1 . Then, the magnetic fluxes  401  are guided by first rings  304   2 ,  304   3 ,  30   4  and  304   5  without being diffused around, to be discharged into an atmosphere. The discharged magnetic fluxes  401  are captured by a second ring  305   5  of a game chip  1055  located in an upper layer. Then, the magnetic fluxes  401  pass through second rings  305   4 ,  305   3 ,  305   2  and  305   1  to be guided to the hollow part of the antenna  202   a  of the reader/writer  202 .  
         [0049]     At the antenna  202   a,  when a current flows in a clockwise direction viewed from the upper surface of the main body  101 , the magnetic fluxes  401  are radiated downward with respect to the antenna  202   a  by a corkscrew rule. The radiated magnetic fluxes  401  are captured by the second ring  305   1  of the game chip  105   1  located in the lower layer. Then, the magnetic fluxes  401  pass through the second rings  305   2 ,  305   3 ,  305   4  and  305   5  to be discharged into an atmosphere. The discharged magnetic fluxes  401  are guided by the first ring  304   5  of the game chip  105   5  located in the upper layer from the upper side of the first ring  304   5  to the hollow part of the first ring  304   5 . Then, the magnetic fluxes  401  are guided by the first rings  304   4 ,  304   3 ,  304   2  and  304   1  without being diffused around, to return to the hollow part of the antenna  202   a  of the reader/writer  202 .  
         [0050]     When the magnetic fluxes  401  cross the hollow part of the antenna coil unit  303   i  of the game chip  105   i  (1≦i≦5), a current is induced at the antenna coil unit  303   i  by electromagnetic induction, and then power is supplied to the IC device  302   i . Then, the game chip  105   i  transmits information stored in the IC device  302   i  to the reader/writer  202  by using load modulation.  
         [0051]     Advantageous features of the game chip  105  will be described.  
         [0052]     In a state where the game chips  105  are stacked in layers, the magnetic fluxes  401  are guided to the first or second ring  304  or  305  of each game chip  105  to reach the game chip  105  located in the upper layer without being diffused around. Accordingly, without greatly reducing the number of magnetic fluxes, the magnetic fluxes  401  can reach the game chip  105  located in the upper layer.  
         [0053]     In the state where the game chips  105  are stacked in layers, when the magnetic fluxes  401  cross the game chip  105  located in the upper layer to be discharged into an atmosphere, the magnetic fluxes  401  are guided to the first or second ring  304  or  305  of each game chip  105  without being diffused around, to return to its radiation source (hollow part of the antenna  202   a ). Accordingly, even if the number of magnetic fluxes emitted from the reader/writer is increased so that the reader/writer surely recognizes the game chip of the upper layer by the electromagnetic induction method, it is possible to prevent the reader/writer from recognizing another game chip, to be read by another reader/writer, set in the area adjacent to the predetermined area.  
         [0054]     Next, a modified example of a game chip will be described.  
         [0000]     (2-2. Game Chip)  
         [0055]     As shown in  FIGS. 6A  to  6 C, a game chip  106  comprises a main body  601 , an IC device (circuit unit)  602 , an antenna coil unit (antenna unit)  603 , a column member (first magnetic flux induction unit)  604 , a ring member (second magnetic flux induction unit)  605  and a substrate  606 . The main body  601  is made of a resin or the like, and is provided with an annular upper plate  601   a,  an annular lower plate  601   b  and a cylindrical side plate  601   c.  The upper and lower plates  601   a  and  601   b  are stuck to both ends of the side plate  601   c.  The main body  601  houses the IC device  602 , the antenna coil unit  603 , the column member  604  and the substrate  606 . The substrate  606  is formed into an annular shape, and arranged on an upper surface of the lower plate  601   b  of the main body  601 . The substrate  606  is coaxial to the main body  601 .  
         [0056]     The IC device  602  is formed into a square column shape, and arranged in the vicinity of a center of the substrate  606 . The IC device  602  is an electronic component for executing a processing function, a storing function and an input/output control function, and transmits information stored therein to a reader/writer  202  in response to an inquiry from the reader/writer  202 .  
         [0057]     The antenna coil unit  603  is formed into an annular shape, and arranged in a peripheral edge of the substrate  606  so as to surround the IC device  602  to be coaxial to the main device  601 . The antenna coil unit  603  is connected to the IC device  602  to support transfer of information between the reader/writer  202  and the IC device  602 . The IC device  602  does not need any battery because the IC device  602  transmits/receives information by using a current induced at the antennal coil unit  603  by fluxes of magnetic lines (magnetic fluxes) emitted from the reader/writer  202 .  
         [0058]     The column member  604  is fitted to hollow parts of the upper and lower plates  601   a  and  601   b  of the main body  601  so as to penetrate the center of the main body  601  to be coaxial to the main body  601 . The column member  604  is made of a material of high relative magnetic permeability. The column member  604  captures magnetic fluxes crossing the main body  601  to prevent the magnetic fluxes from leaking to the outside of the game chip  106 .  
         [0059]     The ring member  605  is fitted to the main body  601  so as to surround an outer peripheral surface of the side plate  601 c of the main body  601  to be coaxial to the main body  601 . The ring member  605  is made of a material of high relative magnetic permeability (e.g. iron or permalloy). The ring member  605  captures magnetic fluxes to prevent the magnetic fluxes from leaking to the outside of the game chip  106 . By arranging the ring member  605  in the outside of the column member  604 , the reader/writer  202  does not read information of another game chip, to be read by another reader/writer, arranged in an area adjacent to the predetermined area. The relative magnetic permeability of the ring member  605  only needs to be higher than that of the main body  601  which has housed the IC device  602  and the antennal coil unit  603 . The ring member  605  has a height h almost equal to that of the column member  604 .  
         [0060]     With this configuration, when the game chips  106  are stacked in layers, the column member  604  and the ring member  605  come into contact with an adjacent column member  604  and an adjacent ring member  605  in an up-and-down direction, respectively. As a result, two paths made of materials having high relative magnetic permeability are formed in the game chip layer.  
         [0000]     (3-2. Information Reading)  
         [0061]     First, a mechanism by which the reader/writer  202  reads information of one game chip  106  will be described.  
         [0062]     The reader/writer  202  generates a carrier wave (AC signal) belonging to a 135 kHz band or a 13.56 MHz band, and modulates the carrier wave and amplifies power based on a base band signal corresponding to transmit data. Then, upon supplying of the carrier wave to an antenna (loop coil)  202   a  of the reader/writer  202 , magnetic fluxes  401  is emitted from a hollow part of the antenna  202   a.    
         [0063]     At the antenna  202   a,  when a current flows in a counterclockwise direction viewed from the upper surface of the main body  601 , the magnetic fluxes  401  are radiated upward with respect to the antenna  202   a  by a corkscrew rule. The radiated magnetic fluxes  401  are captured by the column member  604  from the lower side of the column member  604  to be discharged into an atmosphere. The discharged magnetic fluxes  401  are captured by the ring member  605  to be guided to the hollow part of the antenna  202   a  of the reader/writer  202  (see  FIG. 7 ).  
         [0064]     At the antenna  202   a,  when a current flows in a clockwise direction viewed from the upper surface of the main body  601 , the magnetic fluxes  401  are radiated downward with respect to the antenna  202   a  by a corkscrew rule. The radiated magnetic fluxes  401  are captured by the ring member  605  to be discharged into an atmosphere. The discharged magnetic fluxes  401  are captured by the column member  604  from the upper side of the column member  604  without being diffused around, to be guided to the hollow part of the antenna  202   a  of the reader/writer  202 .  
         [0065]     When the magnetic fluxes  401  cross the hollow part of the antenna coil unit  603 , a current is induced at the antenna coil unit  603  by electromagnetic induction, and then power is supplied to the IC device  602 . Thus, the game chip  106  and the reader/writer  202  constitute an electromagnetic induction coupling circuit. When the induced current is supplied to the IC device  602 , the game chip  106  transmits information stored in the IC device  602  to the reader/writer  202  by using load modulation.  
         [0066]     Next, a mechanism by which the reader/writer  202  reads information of a plurality of game chips  106  (five game chips in this embodiment) stacked in layers will be described.  
         [0067]     The reader/writer  202  generates a carrier wave (AC signal) belonging to a 135 kHz band or a 13.56 MHz band, and modulates the carrier wave and amplifies power based on a base band signal corresponding to transmit data. Then, upon supplying of the carrier wave to the antenna (loop coil)  202   a  of the reader/writer  202 , the magnetic fluxes  401  are emitted from the hollow part of the antenna  202   a.    
         [0068]     At the antenna  202   a,  when a current flows in a counterclockwise direction viewed from the upper surface of the main body  601 , the magnetic fluxes  401  are radiated upward with respect to the antenna  202   a  by a corkscrew rule (see  FIG. 8 ). The radiated magnetic fluxes  401  are captured by a column member  604   1  of a game chip  106   1  located in a lower layer from a lower side of the column member  604   1 . Then, the magnetic fluxes  401  pass through column members  604   2 ,  604   3 ,  604   4  and  604   5  without being diffused around, to be discharged into an atmosphere. The discharged magnetic fluxes  401  are captured by a ring member  605   5  of a game chip  106   5  located in an upper layer. Then, the magnetic fluxes  401  pass through ring members  605   4 ,  605   3 ,  605   2  and  605   1  to be guided to the hollow part of the antenna  202   a  of the reader/writer  202 .  
         [0069]     At the antenna  202   a,  when a current flows in a clockwise direction viewed from the upper surface of the main body  601 , the magnetic fluxes  401  are radiated downward with respect to the antenna  202   a  by a corkscrew rule. The radiated magnetic fluxes  401  are captured by the ring member  605   1  of the game chip  106   1  located in the lower layer. The magnetic fluxes  401  pass through the ring members  605   2 ,  605   3 ,  605   4  and  605   5  to be discharged into an atmosphere. The discharged magnetic fluxes  401  are captured by the column member  604   5  of the game chip  106   5  located in the upper layer from the upper side of the column member  604   5 . Then, the magnetic fluxes  401  pass through the column members  604   4 ,  604   3 ,  604   2  and  604   1  without being diffused around, to be guided to the hollow part of the antenna  202   a  of the reader/writer  202 .  
         [0070]     When the magnetic fluxes  401  cross the hollow part of the antenna coil unit  603   i  of the game chip  106   i  (1≦i≦5), a current is induced at the antenna coil unit  603   i  by electromagnetic induction, and then power is supplied to the IC device  602   i . Then, the game chip  106   i  transmits information stored in the IC device  602   i  to the reader/writer  202  by using load modulation.  
         [0071]     Advantageous features of the game chip  106  will be described.  
         [0072]     In a state where the game chips  106  are stacked in layers, the magnetic fluxes  401  are guided to the column member  604  or the ring member  605  of each game chip  106  to reach the game chip  106  located in the upper layer without being diffused around. Accordingly, without greatly reducing the number of magnetic fluxes, the magnetic fluxes  401  can reach the game chip  106  located in the upper layer.  
         [0073]     In the state where the game chips  106  are stacked in layers, when the magnetic fluxes  401  cross the game chip  106  located in the upper layer to be discharged into an atmosphere, the magnetic fluxes  401  are guided to the column member  604  or the ring member  605  of each game chip  106  without being diffused around, to return to its radiation source (hollow part of the antenna  202   a ). Accordingly, even if the number of magnetic fluxes emitted from the reader/writer is increased so that the reader/writer surely recognizes the game chip of the upper layer by the electromagnetic induction method, it is possible to prevent the reader/writer from recognizing another game chip, to be read by another reader/writer, set in the area adjacent to the predetermined area.