Abstract:
To realize a display driver chip for an information medium having a display function adaptable to any information medium chip, the information medium having a display function includes first communication means for transmitting and receiving information to and from a reader/writer in a contactless manner, second communication means having a communication interface that is the same as that of the first communication means and receiving information from the reader/writer independently of the first communication means, and display means for displaying information received from the reader/writer by the second communication means. Thus, it is possible to mount a memory display panel without modifying the configuration of the information medium chip such as a conventional IC card chip and the same display driver chip can be used for any information medium chip.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation of international PCT application No. PCT/JP2005/005027 filed on Mar. 18, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an information medium such as a contactless IC card, an RFID tag or the like that transmits and receives information to and from a reader/writer device in a contactless manner, and particularly to an information medium that has a display unit and performs transmission and reception of data to and from a reader/writer device in a contactless manner.  
         [0004]     2. Description of the Related Art  
         [0005]     Information media that transmit and receive data to and from reader/writer devices in a contactless manner have rapidly become common in recent years. Information media such as contactless IC cards and the like that transmit and receive data to and from reader/writer devices have not allowed the printing and displaying of information such as the remaining balance of pre-paid cards, incentive points given when shopping, or the like by using reader/writer devices. In order to solve this problem, a contactless IC card  10  is suggested that includes an image memory display panel  30  that can maintain a display state even when a power supply stops (for example, a cholesteric liquid crystal display panel of a selective reflection type that uses liquid crystals forming a cholesteric phase) as shown in  FIG. 1 . This contactless IC card  10  allows the displaying of information such as the remaining balance on a pre-paid card, incentive points, or the like by employing a configuration in which a signal line and a power supply line that extend from the contactless IC card chip are connected to the display driver chip of the semipermanent memory display panel  30 .  
         [0006]      FIG. 2  shows a configuration of a commonly used contactless IC card  20  that does not have a display function. The contactless IC card  20  employs a configuration in which, for example, an IC card chip  24  is mounted on a film substrate  22 , a loop antenna  26  forms a plurality of loops on the film substrate  22  and around the IC card chip  24 , the end of the film substrate  22  is connected to the IC card chip  24  via a through hole  29 , and the bottom surface of the contactless IC card  20  is covered entirely by a PET cover  28 .  
         [0007]     The contactless IC card  20  performs communications, via the loop antenna  26  included in the contactless IC card  20  itself, with a computer having a reader/writer connected. It requires no signal line except for the loop antenna  26 .  
         [0008]     Accordingly, when an image memory display panel is to be included in a contactless IC card, it has been necessary to modify the configuration of the contactless IC card chip  34  in such a manner that the chip includes signal lines and a power supply line, as shown in  FIGS. 3 and 4 .  
         [0009]     Hereinafter, the contactless IC card  10  that is of a conventional type and that includes the image display panel  30  is explained by referring to  FIGS. 3 and 4 .  
         [0010]     The image memory display panel  30  shown in  FIG. 1 , which are not shown in  FIG. 3  or  FIG. 4 , comprises a display element  32  and an LCD driver  31 . The LCD driver  31  comprises a segment driver  313  for driving segments in the display element  32 , a common driver  314  for driving a common electrode in the display element, an interface  312  for controlling the segment driver  313  and the common driver  314  by converting signals in accordance with the timings at which the signals from the IC card chip  34  are received, and a display unit power source  311  for supplying driving power to the segment driver  313  and the common driver  314  on the basis of the power supplied from the IC card chip.  
         [0011]     The configuration of the IC card chip  34  has to be modified such that signal lines and power supply lines extend from the IC card chip  34  in order to supply, to the image memory display panel  30  through the interface  312 , the power and data acquired via a loop antenna  36 .  
         [0012]     In the case of, for example, a TYPE-B card used as a Basic Resident Register card in Japan, the IC card chip is an LSI including a 32-bit CPU, and it is very costly to modify the configurations of such devices. This high cost of modifying configurations of IC cards is the greatest factor preventing the spread of the use of IC cards having a display function. Also, because there are a plurality of combinations of levels of power voltages and signals of IC card chips, a plurality of types of display drivers are required.  
         [0013]     As an example of a device having the above described configuration, Patent Document 1 discloses an electronic medium such as an RFID tag that includes a display unit and a contactless communication unit for receiving a supply of power and transmitting and receiving digital information. In this electronic medium too, the display unit is driven by the contactless communication unit.  
         [0014]     Patent Documents 2 and 3 disclose methods of realizing a image memory display by using a contactless IC card that has a configuration different than the above.  
         [0015]     Patent document 2 discloses a technique of driving a display unit by receiving means for incident light that expresses information in addition to a conventional contactless communication means. The method disclosed in Patent Document 2 does not require a configuration modification in a contactless communication means. However, this method requires a configuration modification in a reader/writer.  
         [0016]     Patent Document 3 discloses a technique of displaying information using heat generated by external electromagnetic waves used for communications with conventional contactless communication units. Accordingly, the displayed contents are greatly limited. Also, because the heat is generated by external electromagnetic waves, there is a probability that some information will be displayed from electromagnetic waves emitted from devices that are not the proper reader/writer. 
    Patent Document 1: Japanese Published Patent Application No. 2004-102840     Patent Document 2: Japanese Published Patent Application No. 2004-127279     Patent Document 3: Japanese Published Patent Application No. H07-68978    
 
       SUMMARY OF THE INVENTION  
       [0020]     It is an object of the present invention to provide a display module as an open resource applicable to any type of information media transmitting and receiving, in a contactless manner, information to and from a reader/writer.  
         [0021]     In order to achieve this object, an information medium having a display function according to the present invention comprises first communication means transmitting and receiving information to and from a reader/writer device in a contactless manner, second communication means having a communication interface that is the same as that of the first communication means and receiving information from the reader/writer in a contactless manner and independently from the first communication means, and display means displaying information received from the reader/writer via the second communication means.  
         [0022]     According to the present invention, an image memory display panel can be mounted on an information medium without modifying the configuration of a chip for the information medium, the chip being a conventional IC card chip or the like. Also, the same display control chip can be used also for a chip that is used in an information medium.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]      FIG. 1  shows the appearance of a conventional contactless IC card having a display function;  
         [0024]      FIG. 2  shows a configuration of a commonly used contactless IC card without a display function;  
         [0025]      FIG. 3  shows a configuration of a conventional contactless IC card having a display function;  
         [0026]      FIG. 4  is a block diagram of the conventional contactless IC card having a display function;  
         [0027]      FIG. 5  is a block diagram of a contactless IC card having a display function according to the present invention;  
         [0028]      FIG. 6  shows a configuration of the contactless IC card having a display function according to the present invention;  
         [0029]      FIG. 7  is a block diagram of a contactless IC card having a display function whose RFID chip and display control chip have an antenna in common that they both use;  
         [0030]      FIG. 8  shows an embodiment of the present invention in which a display module is attached to a contactless IC card so that the card can be used as a contactless IC card having a display function;  
         [0031]      FIG. 9  shows communication feasibility relationship between the contactless IC card having a display function according to the present invention and an RFID reader/writer corresponding to their communication protocol; and  
         [0032]      FIG. 10  shows process sequences between the contactless IC card having a display function and an RFID reader/writer in their respective communication procedures. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]     Hereinafter, embodiments of the present invention will be explained by using, as an example of a contactless information medium, a contactless IC card including an RFID chip as an IC card chip.  
         [0034]     First, the principle and a first embodiment of the present invention will be explained by referring to  FIGS. 5 through 7 .  
         [0035]     As shown in  FIG. 5 , a display control chip  41  according to the present invention comprises an IC card interface  412  to which an antenna  416  is connected in order to realize transmission and reception of signals to and from IC card reader/writers via the same communication interface as that of an IC card chip  44 , which is different from the conventional LCD driver  31  shown in  FIG. 4 . Accordingly, it is not necessary to modify the configuration of the IC card chip, and the IC card chip  44  shown in  FIG. 5  can be the same as the IC card chip  24  shown in  FIG. 2  because it is possible to receive display data directly from a reader/writer. Also, a display unit power source  411  for a display element  42  and a display control chip  41  constituting a display module  40 , a segment driver  413 , and a common driver  414  can be the same as a conventional display unit power source  311 , segment driver  313 , and common driver  314  shown in  FIG. 4 . The antenna for the display control chip can be a type embedded in a display control chip  41  similarly to the antenna  416  shown in  FIG. 5 . By embedding the antenna on chip, manufacturing costs can be reduced. The IC card interface  412  comprises a logic power source circuit (“5V” in  FIG. 4  corresponds to this circuit) that is not shown in any figure, and the power is supplied to the respective units in the display control chip  41 . By using this power, the display unit power source  411  generates driving power for the display element  42 .  
         [0036]     A contactless IC card  50  having the display function shown in  FIG. 6  is an embodiment variation for the antenna in the first embodiment. In this embodiment variation, an antenna  56  for the display control chip  51  is not embedded in the display control chip  51 , and is disposed on a portion of a display module  55  that is outside of the display control chip  51 . The antenna  56  is disposed outside of the display control chip, and accordingly a degree of freedom in designing the display control chip increases.  
         [0037]      FIG. 7  shows a contactless IC card  60  having a display function as another embodiment variation for the antenna in the first embodiment. A single antenna  66  is used for both an IC card chip  44  and a display control chip  61 . By using a single antenna for both chips, the manufacturing costs can be reduced.  
         [0038]     The antennas  46  and  66  for the IC card chip  44  have to be redesigned while taking into consideration the changes in the resonance frequencies because the display module according to the present invention is mounted on a conventional contactless IC card.  
         [0039]     However, because a manufacturing tolerance of about 5% in the resonant frequency for a conventional contactless IC card is accepted, it is not necessary to modify the configuration of the antenna for the IC card chip if changes in the resonance frequencies occurring when the display module is mounted are kept within this tolerance.  
         [0040]     Next, a second embodiment of the present invention will be explained; in this embodiment, it is not necessary to modify the configuration of a conventional antenna for an IC card chip.  
         [0041]     First, conditions are explained that are required for a display module to suppress the resonance frequency change to within 5% when the display module according to the present invention is mounted on a conventional contactless IC card.  
         [0042]     According to the analysis based on electromagnetics, the resonance frequency change that results when a display module is mounted depends upon the ratio of load current in an antenna used for a display module to load current in an antenna used for an IC card chip. When the resonance frequency of a conventional contactless IC card is 13.56 MHz and 95% (i.e., within 5%) of the frequency change occurs when a display module is mounted, it is sufficient if the load current for the display module is equal to or lower than 5.4% of the load current in the antenna for the IC card chip, i.e., equal to or lower than 10.8% of the electric power.  
         [0043]     Because the power consumption in a typical RFID chip is 5 mW, the upper limit of the power consumption in the display module is 0.54 mW, and this value is sufficiently feasible.  
         [0044]     Accordingly, by limiting the upper limit value of the power consumption in the display module, it is possible to realize the second embodiment of the present invention, in which the configuration of an antenna for an RFID chip does not have to be modified, while employing any of the arrangements of an antenna shown in  FIGS. 5 through 7 . Also, as a configuration in the second embodiment of the present invention, any of the configurations shown in  FIGS. 5 through 7  can obviously be employed as long as the limitation on the power consumption of the display module does not prevent it.  
         [0045]     Next, a third embodiment of the present invention is explained; in this embodiment, it is not necessary to modify the configuration of a conventional contactless IC card itself.  
         [0046]     According to the present invention, because it is not necessary to connect a conventional IC card chip and a display control chip with a signal line or a power line, a display module having a display element, a display control chip, and an antenna is held in a state such that the display module closely contacts a contactless IC card, and accordingly it is possible to realize a contactless IC card having a display function without modifying the configuration of a conventional contactless IC card.  
         [0047]     As it is shown in  FIG. 8 , the mechanism by which a contactless IC card holds a display module is achieved by, for example, providing an adhesive part  81  on a rear face of a display module  80  such that the display module  80  is attached to a contactless IC card  70 . In this case, it is desirable that an area  79  to which a display module can be attached be indicated as shown in, for example,  FIG. 8 . Also, in order to achieve stable operations, it is desirable that the resonant frequency of the entirety including the display module  80  and the contactless IC card  70  in a closely contacting state be equal to or higher than 95% of the resonant frequency of the contactless IC card  70  alone.  
         [0048]     Finally, a communication procedure executed for communications between a contactless IC card having a display function according to the present invention and an RFID reader/writer will be explained.  
         [0049]     A standard is defined for a communication procedure between RF reader/writers and conventional contactless IC cards including RFID chips, and in the standard, an anti-collision procedure for authenticating IC cards, preventing collisions among a plurality of IC cards, and realizing operations of the plurality of IC cards at one moment is defined.  
         [0050]     Accordingly, transmission and reception of signals are realized between a reader/writer and contactless IC cards in the following manner. First, the reader/writer recognizes and detects a main RFID chip by performing polling on the basis of the anti-collision procedure, and perform usual communications. Next, the reader/writer detects the display control chip by performing polling, and transmits data to be displayed. The display control chip receives the data to be displayed, and displays the data on the image memory display panel.  
         [0051]     However, performing the anti-collision procedure takes much time; accordingly, it is also possible to employ a write procedure without authentication instead of the anti-collision procedure for the communications in which display data is only transmitted to the display control chip.  
         [0052]      FIG. 9  shows relationships in which communications are possible between RFID reader writers and the contactless IC cards having a display function corresponding to the respective procedures. The process performed by the RFID reader/writer according to the present invention includes processes performed by firmware (base FW) and processes performed by user application programs (UP-A, UP-B, and UP-C) corresponding to the respective procedures. Both the RFID reader/writer and the IC card having a display function can be adapted to the anti-collision procedure and the write procedure without authentication.  
         [0053]     Accordingly, there are three types respectively of the RFID reader/writer and the contactless IC card having a display function, and the combinations that allow communications are shown in  FIG. 9 . A contactless IC card  200  having a display function that adopts the anti-collision procedure can perform communications with an RFID reader/writer  100  that adopts the anti-collision procedure and with an RFID reader/writer  120  that adopts both of the procedures. A contactless IC card  210  having a display function that adopts the write procedure without authentication can perform communications with an RFID reader/writer  110  that adopts the write procedure without authentication and with the RFID reader writer  120  that adopts both of the procedures. A contactless IC card  220  having a display function that adopts both of the procedures can perform communications with three types of RFID reader/writers  100 ,  110 , and  120 .  
         [0054]      FIG. 10  shows process sequences in the respective procedures.  
         [0055]     First, the case is explained in which the RFID reader/writer adopts the anti-collision procedure and the contactless IC card having a display function adopts the anti-collision procedure.  
         [0056]     The RFID chip and the display control chip respectively return responses in response to the polling of the RFID reader/writer. The RFID reader/writer selects one partner (in this case, the RFID chip) by applying the anti-collision procedure in response to these responses, and authenticates the RFID chip. When the authentication is terminated, a normal communication is performed in accordance with the application. Thereafter, the polling is again performed, and the display control chip is authenticated in response to the response from the display control chip. When the authentication succeeds, display data is written to the display control chip by using the device ID of the display control chip that was acquired upon the authentication. The display control chip displays the display data on the display element.  
         [0057]     Next, the case is explained in which the RFID reader/writer adopts the write procedure without authentication and the contactless IC card having a display function adopts the write procedure without authentication.  
         [0058]     In this case, only the RFID chip makes responses to the polling of the RFID reader/writer, and a normal communication is performed with the RFID chip after the authentication procedure. After this communication, the RFID reader/writer makes a requests for the device ID of the display control chip from the RFID chip. The RFID chip holds the device ID of the display control chip, and the device ID is transmitted to the RFID reader/writer. The RFID reader/writer attaches the device ID to the write data and transmits the data to the display control chip. Additionally, the device ID of the display control chip can be calculated from the device ID of the RFID chip acquired upon authentication of the RFID chip when the device ID of the display control chip is in a particular relationship with the device ID of the RFID chip to which the display control chip corresponds.  
         [0059]     Next, the case is explained in which the RFID reader/writer can communicate with both the card of the anti-collision procedure and the card of the write procedure without authentication. The process sequence that is the same as that for the above combination between the anti-collision procedures is performed on the card of the anti-collision procedure because the display control chip responds to the polling. The display data is written to the card of the write procedure without authentication in accordance with the write procedure without authentication after recognizing the card to be a card of the write procedure without authentication on the basis of the fact that there is no response from the display control chip.  
         [0060]     Next, the case is explained in which the contactless IC card having a display function can communicate with both the RFID reader/writer of the anti-collision procedure and the REID reader/writer of the write procedure without authentication. In the case in which the RFID reader/writer can communicate with the card of the anti-collision procedure or can communicate with both the card of the anti-collision procedure and the card of the write procedure without authentication, the display control chip responds to polling; accordingly, the process sequence is the same as that for the above combination of anti-collision procedures. When the RFID reader/writer can communicate only with the card of the write procedure without authentication, polling to the display control chip is not performed, and the process proceeds in accordance with the write procedure without authentication.  
         [0061]     In the above, the present invention has been explained by using a contactless IC card as an example of an information medium. However, it is obvious that the form of the information media used in the present invention is not limited to a card.  
         [0062]     Also, as is obvious from the above explanations, according to a characteristic of the present invention, it is possible to add a display function to a core portion of a conventional information medium without modifying its configuration. Also, according to another characteristic of the present invention, it is possible to eliminate the necessity for modifying the configuration of an antenna of conventional information media. Further, according to still another characteristic of the present invention, it is possible to add a display function without modifying a configuration of a conventional information medium itself.  
         [0063]     Further, display data that is transmitted to the display module from the reader/writer is not limited to results of processing in the reader/writer (such as remaining balance or the like), and it is also possible to transmit to the display module of the information medium via the reader/writer data that was processed on the information medium itself, in order to display this data.