Abstract:
A printing medium has means for storing electronic data. The means includes an input-output unit, a first memory, a second memory, a comparison unit, and an access controller. The second memory stores data for confirming the validity of the information printed on the printing medium. The first memory stores data for controlling access to the second memory. In particular, write access to the second memory is denied unless the accessing party also submits comparison data that compare correctly with the data stored in the first memory. This protocol prevents the facile creation of counterfeit copies.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a printing medium that can also store electronic data, to an image forming apparatus for printing an image on the printing medium, and to a method of printing on the printing medium, more particularly to a method that deters counterfeiting.  
         [0003]     2. Description of the Related Art  
         [0004]     The increasing quality of the images turned out by color copiers and other image forming apparatus has made the creation of faithful copies of printed matter a simple undertaking. There is accordingly a need for printing media equipped with effective means of preventing counterfeiting, that is, of preventing the illegal copying and use of printed matter having negotiable value, such as tickets and securities. Known means include both means for validating the image or information printed on the printing medium, and means that make the printing medium intrinsically difficult to copy. Both means may be employed simultaneously.  
         [0005]     Known validation methods include the printing of a bar code generated from the printing data from which the printed image is generated, and the addition of predetermined information to the printing data, so that the printed image provides its own validation information. Known methods of making the printing medium difficult to copy include the addition of an optically variable mark such as a hologram to the printing medium. In a further method, disclosed in Japanese Unexamined Patent Application Publication No. 2000-285203, an integrated circuit (IC) chip is embedded in the printing medium to store validation data electronically; the validation data can be read from the IC chip to verify that the document printed on the printing medium is genuine.  
         [0006]     Printing media incorporating an IC chip are secure from counterfeiting by image forming apparatus, because an image forming apparatus cannot copy the data stored in the IC chip, but such printing media are not useful unless they provide means of read and write access to the IC chip. In the above disclosure, read access and write access are virtually unrestricted, making it impossible to protect the secrecy of the data recorded in the IC chip. A suitably equipped counterfeiter can make an accurate copy of the negotiable security, ticket, or other image printed on the printing medium, then read the data recorded in the embedded IC chip and write identical data into a similar IC chip embedded in the copy, thereby producing a counterfeit copy that is substantially indistinguishable from the genuine original.  
       SUMMARY OF THE INVENTION  
       [0007]     An object of the present invention is to provide a printing medium, image forming apparatus, and printing method that improve the secrecy of data electronically stored in the printing medium.  
         [0008]     The present invention provides a printing medium that can also store electronic data. The printing medium includes an input-output unit, a first memory, a second memory, a comparison unit, and an access controller. The first memory stores authentication data. The comparison unit generates a comparison result by comparing the authentication data with comparison data. The input-output unit inputs the comparison data and outputs the comparison result. The second memory stores validation data corresponding to an image printed on a surface of the printing medium. The access controller controls write access to the second memory according to the comparison result generated by the comparison unit.  
         [0009]     By making write access to the second memory conditional on the provision of comparison data and the result of a comparison between the comparison data and the authentication data stored in the first memory, the invention makes it difficult to create a counterfeit copy including correct validation data.  
         [0010]     To make the creation of counterfeit copies even more difficult, the access controller may also control read access to the second memory. The printing medium may include an additional access controller for controlling write access to the first memory, so that additional data can be appended to the authentication data to provide still further security.  
         [0011]     The invention also provides a method of printing on the invented printing medium, and an image forming apparatus for printing on the invented printing medium. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     In the attached drawings:  
         [0013]      FIG. 1  illustrates the structure of a printing medium according to a first embodiment of the invention;  
         [0014]      FIG. 2  is a block diagram showing the internal structure of the IC chip in the printing medium in  FIG. 1 ;  
         [0015]      FIG. 3  is a block diagram of an image forming apparatus according to the first embodiment of the invention;  
         [0016]      FIG. 4  is a diagram showing the region in which the communication unit in the image forming apparatus in  FIG. 3  can communicate with the printing medium in  FIG. 1 ;  
         [0017]      FIGS. 5A and 5B  are flowcharts illustrating the printing operation and the writing of data in the first embodiment;  
         [0018]      FIGS. 6A and 6B  are flowcharts illustrating the reading of data in the first embodiment; and  
         [0019]      FIG. 7  is a block diagram showing the internal structure of the IC chip in a second embodiment of the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     Embodiments of the invention will now be described with reference to the attached drawings.  
         [0021]     Referring to  FIG. 1 , the first embodiment is a printing medium  1  to which a small IC chip  2  is attached. The IC chip  2  is fastened to the printing medium  1  by an adhesive and is sealed by a heat-resistant seal  3 . The IC chip  2 , is surrounded by a loop antenna  4 .  
         [0022]     In  FIG. 1 , the IC chip  2  is attached near the front right corner of the printing medium  1  with respect to the direction in which the printing medium  1  is transported during printing, but the IC chip  2  may be attached anywhere, on either side of the printing medium  1 , as long as it is located near the front of the printing medium  1  with respect to the printing transport direction. The IC chip  2  may be fastened to the printing medium  1  by any means that prevent removal from the printing medium  1 ; for example, the IC chip  2  may be inserted into the printing medium  1 .  
         [0023]     Referring to  FIG. 2 , the IC chip  2  attached to the printing medium  1  comprises an antenna unit  5 , an input-output controller  6 , an access controller  7 , a comparison unit  8 , a first memory  9 , and a second memory  10 . The IC chip  2  uses a contactless communication system in which data are transmitted and received from the antenna unit  5  via the loop antenna  4  shown in  FIG. 1 . The antenna unit  5  also supplies power received via the loop antenna  4  to the IC chip  2 . The input-output controller  6  controls the input and output of data received and transmitted from the antenna unit  5 . The access controller  7  controls access to the data stored in the IC chip  2 . The comparison unit  8  decides whether access to the data stored in the IC chip  2  is authorized or not. The first memory  9  and second memory  10  are both nonvolatile memories. Authentication data used in decision making by the comparison unit  8  are prestored in the first memory  9 ; validation data transmitted and received as described above are stored in the second memory  10 .  
         [0024]      FIG. 3  illustrates an image forming apparatus  11  used in the first embodiment of the invention. The image forming apparatus  11  is connected to an external device  12  such as a personal computer or other information processing apparatus. The image forming apparatus  11  prints an image on the printing medium  1 , and can also access the IC chip  2  to read and write data.  
         [0025]     As shown in  FIG. 3 , the image forming apparatus  11  comprises an input-output unit  13 , a controller  14 , an operation panel  15 , a communication unit  16 , and an image forming unit  17 .  
         [0026]     The input-output unit  13  is an interface circuit that exchanges data with the external device  12 . The input-output unit  13  may be, for example, a USB (universal serial bus) interface circuit, a LAN (local area network) interface circuit, or an RS-232C (Electronic Industries Association recommended standard No. 232 version C) interface circuit.  
         [0027]     The controller  14  receives data from the input-output unit  13  and converts the received data into various forms, as well as controlling the entire image forming apparatus  11 . The controller  14  includes a memory storing various embedded programs, a processor for executing these programs, and a work memory.  
         [0028]     The operation panel  15  displays the status of the image forming apparatus  11  according to information received from the controller  14 , and has buttons, keys, or other manual controls for input of various types of information, which is sent to the controller  14 .  
         [0029]     The communication unit  16  exchanges data with the printing medium  1 . Referring to  FIG. 4 , the communication unit  16  (not visible) in the image forming apparatus  11  can communicate with the printing medium  1  when the printing medium  1  is in a communication region  18 . The conditions satisfied by the communication region  18  include, for example, enabling electromagnetic waves transmitted from the communication unit  16  to reach the printing medium  1  with a certain electric power, and not permitting the electromagnetic waves to reach any other printing media which are stacked or stored in preparation for printing.  
         [0030]     The image forming unit  17  prints an image on a surface of the printing medium  1  as it is transported through the image forming apparatus  11 .  
         [0031]     The printing medium  1  incorporating the IC chip  2  may be used for various purposes. To address the problems of the prior art described above, the following descriptions will assume that the printing medium  1  is used for printing a negotiable security.  
         [0032]     To make the printing medium  1  into a negotiable security incorporating the IC chip  2 , two processes must be performed: first, the title and other information of the security must be printed on the printing medium  1 , and second, information that can certify the validity of the printing medium  1  when it is used as a negotiable security must be stored in the second memory  10  of the IC chip  2 . The validity of the negotiable security is verified by comparing the information printed on the printing medium  1  with the information (validation data) stored in the second memory  10 .  
         [0033]     The validation data are stored in the second memory  10  when an image is printed on the printing medium  1 , to certify the validity of the image printed on the printing medium  1 . In this first embodiment, it is assumed that the information printed on the printing medium  1  includes at least the price of the negotiable security, and that the price data are used as the validation data. In practice, the validation data may be any data that can be compared with the image printed on the printing medium  1  for verification purposes. Instead of price data, the validation data may be, for example, issuer data, owner data, or issue date data, or an encrypted form of any of these data.  
         [0034]     To write the validation data when the external device  12  requests printing of the negotiable security by sending data to be printed, the comparison unit  8  first decides whether to permit write access to the second memory  10 . If write access is permissible, the input-output controller  6  transfers the validation data received via the antenna unit  5  to the access controller  7 , which writes the transferred validation data into the second memory  10 . If write access is not permissible, the receiving and writing of the validation data are not carried out.  
         [0035]     To read the validation data when the external device  12  requests reading of data to verify the authenticity of the negotiable security, the comparison unit  8  first decides whether to permit read access to the second memory  10 . If read access is permissible, the access controller  7  reads the validation data from the second memory  10  and transfers the validation data to the input-output controller  6 , which transmits the transferred data via the antenna unit  5 . If read access is not permissible, the reading and transmitting of the validation data are not carried out.  
         [0036]     The authentication data prestored in the first memory  9  are used to decide whether to permit these read and write accesses. The authentication data are prestored in the first memory  9  before the IC chip  2  is attached to the printing medium  1 , and used to authorize access to the IC chip  2 . The authentication data may be any data associated with the printing medium  1 , such as data identifying the manufacturer of the IC chip  2 , data identifying the security issuer who performs printing on the printing medium  1 , data identifying the media type of the printing medium  1 , or serial number data. In this first embodiment, data identifying the media type of the printing medium  1  (media data) are employed as authentication data.  
         [0037]     The image forming apparatus  11  is thus equipped both to print a negotiable security on the printing medium  1  and to read and write the security price data in the second memory  10 . Printing is carried out according to printing data sent from the external device  12  to the input-output unit  13 . The controller  14  receives the printing data from the input-output unit  13 , and converts the received printing data into image data to be printed on the printing medium  1  and security price data to be stored in the second memory  10 , while transporting or pre-feeding the printing medium  1  to a predetermined location in the communication region  18 . Subsequently, the controller  14  causes the operation panel  15  to display a prompt for input of comparison data. After the operator of the image forming apparatus  11  enters the comparison data on the operation panel  15 , the controller  14  sends the comparison data to the printing medium  1  via the communication unit  16  to confirm the possibility of write access to the second memory  10 .  
         [0038]     After sending the comparison data, the controller  14  receives a comparison result from the printing medium  1  via the communication unit  16 . If the comparison result indicates that data can be written in the printing medium  1 , the image forming unit  17  performs printing on the printing medium  1  while the communication unit  16  sends the security price data to the IC chip  2  attached to the printing medium  1 . If data cannot be written, printing is canceled and the printing medium  1  is fed back from the communication region  18  into the tray shown at the bottom of  FIG. 4 . Alternatively, the printing medium  1  may be fed through the image forming apparatus  11  and ejected with no printing performed, so that the surface of the printing medium  1  remains blank. The conversion of the printing data to image data may also be delayed until the comparison result has been received, and performed only if the comparison result indicates that the writing of data is possible.  
         [0039]     When the security price data stored in the second memory  10  are read, a read request sent by the external device  12  initiates processing by the controller  14 , in which the comparison data entered on the operation panel  15  is sent to the printing medium  1  to confirm whether read access to the printing medium  1  is permissible or not. If read access is permissible, the security price data received from the printing medium  1  are displayed on the operation panel  15 . If read access is not permissible, an error message is displayed on the operation panel  15 . Alternatively, the price data and/or error message may be displayed on the external device  12  instead of the operation panel  15 .  
         [0040]     The flowcharts in  FIGS. 5A and 5B  illustrate the image printing and data writing operations in the first embodiment.  FIG. 5A  shows operations performed by the image forming apparatus  11 ;  FIG. 5B  shows operations performed by the IC chip  2 . The printing and writing operations will be described below with reference to these flowcharts.  
         [0041]     First, the controller  14  in the image forming apparatus  11  receives printing data from the external device  12  via the input-output unit  13  (step  101  in  FIG. 5A ). While pre-feeding the printing medium  1 , the controller  14  converts the received printing data by executing an embedded program to generate image data to be printed on the printing medium  1  and price data to be sent to the printing medium  1  (step  102 ).  
         [0042]     After completion of the above data conversion, the controller  14  requests the entry on the operation panel  15  of comparison data necessary for authorization of write access to the second memory  10 , and sends the entered comparison data to the printing medium  1  via the communication unit  16  (step  103 ).  
         [0043]     The IC chip  2  transfers the above comparison data received via the antenna unit  5  to the comparison unit  8  via the input-output controller  6 . (step  111  in  FIG. 5B ). The comparison unit  8  compares the received comparison data with the authentication data (media data) prestored in the first memory  9 , and decides from the comparison result whether data can be written into the second memory  10  (step  112 ). If the comparison result indicates that the comparison data match the authentication data, the comparison unit  8  sends a write access permission signal through the input-output controller  6  and antenna unit  5 , notifying the image forming apparatus  11  that writing of data is possible, while sending the same notification to the access controller  7  in the IC chip  2  (step  113 ). If the comparison result indicates that the comparison and authentication data do not match, the comparison unit  8  sends a write access denial signal through the input-output controller  6  and antenna unit  5 , notifying the image forming apparatus  11  that writing of data is not possible (step  114 ).  
         [0044]     The communication unit  16  in the image forming apparatus  11  receives the comparison result sent from the IC chip  2  and transfers it to the controller  14  (step  104  in  FIG. 5A ), which decides from the comparison result whether data can be written or not (step  105 ). If the comparison result indicates that data can be written, the controller  14  controls the image forming unit  17  to print the image data on the pre-fed printing medium  1 , and sends the price data to the printing medium  1  via the communication unit  16  (step  106 ). If the above comparison result indicates that data cannot be written, the controller  14  returns the pre-fed printing medium  1  to the printer tray without printing (step  107 ).  
         [0045]     If the IC chip  2  sends a write access permission signal (in step  113  in  FIG. 5B ), the price data received via the antenna unit  5  are sent to the access controller  7  via the input-output controller  6  (step  115 ) and written into the second memory  10  by the access controller  7  (step  116 ). If the IC chip  2  sends a write access denial signal (in step  114 ), the price data are not written into the second memory  10 .  
         [0046]      FIGS. 6A and 6B  are flowcharts illustrating the reading of data in the first embodiment.  FIG. 6A  shows operations performed by the image forming apparatus  11 ;  FIG. 6B  shows operations performed by the IC chip  2 . The reading of data will be described below with reference to these flowcharts.  
         [0047]     First, the controller  14  in the image forming apparatus  11  receives a read request from the external device  12  via the input-output unit  13  (step  201  in  FIG. 6A ). The controller  14  then executes an embedded program that causes the operation panel  15  to display a prompt for entry of the comparison data necessary to authorize the reading of data from the second memory  10 , and sends the entered comparison data to the printing medium  1  via the communication unit  16 , while pre-feeding the printing medium  1  (step  202 ).  
         [0048]     The IC chip  2  attached to the pre-fed printing medium  1  transfers the comparison data received via the antenna unit  5  to the comparison unit  8  via the input-output controller  6  (step  211  in  FIG. 6B ). The comparison unit  8  compares the received comparison data with the authentication (media) data prestored in the first memory  9 , and decides from the comparison result whether data can be read from the second memory  10  nor not (step  212 ). If the comparison result indicates that the comparison and authentication data match, the comparison unit  8  sends a read access permission signal to the access controller  7 , and to the image forming apparatus  11  via the input-output controller  6  and antenna unit  5 , indicating that data can be read (step  213 ). If the comparison result indicates that the comparison and authentication data do not match, the comparison unit  8  sends a read access denial signal to the image forming apparatus  11  via the input-output controller  6  and antenna unit  5 , indicating that data cannot be read (step  214 ). When data can be read, the access controller  7  reads the price data stored in the second memory  10  and transfers the price data to the input-output controller  6 , which sends the transferred price data to the image forming apparatus  11  via the antenna unit  5  (step  215 ).  
         [0049]     In the image forming apparatus  11 , the comparison result sent from the IC chip  2  is received by the communication unit  16  and transferred to the controller  14  (step  203  in  FIG. 6A ). The controller  14  then decides from the comparison result whether reading of data is possible or not (step  204 ). If the comparison result indicates that reading of data is possible, the controller  14  receives the price data sent from the IC chip  2  attached to the pre-fed printing medium  1  via the communication unit  16 , converts the price data to data that can be displayed on the operation panel  15  by executing an embedded program, displays the converted data on the operation panel  15  (step  205 ) and ejects the pre-fed printing medium  1  (step  206 ). If the comparison result indicates that reading of data is not possible, the controller  14  displays an error message and ejects the pre-fed printing medium  1  (step  206 ).  
         [0050]     As described above, according to the first embodiment, access to the data stored in the IC chip  2  is allowed only when entered comparison data match the authentication data prestored in the IC chip  2 , whereby access to the IC chip  2  can be restricted and the secrecy of the data stored therein can be improved, making the counterfeiting process more difficult.  
         [0051]     Next, a second embodiment of the invention will be described.  
         [0052]      FIG. 7  is a block diagram showing the internal structure of the IC chip in the second embodiment of the invention. The IC chip  26  in  FIG. 7  corresponds to the IC chip  2  of the printing medium  1  in the first embodiment shown in  FIG. 1 . The image forming apparatus in the second embodiment of the invention is identical to the image forming apparatus in the first embodiment shown in  FIGS. 3 and 4 .  
         [0053]     As shown in  FIG. 7 , the IC chip  26  comprises an antenna unit  19 , an input-output controller  20 , a first access controller  21 , a second access controller  22 , a comparison unit  23 , a first memory  24 , and a second memory  25 . The operations of these blocks are similar to those of the antenna unit, input-output controller, access controller, comparison unit, first memory, and second memory in the first embodiment described above. As in the first embodiment, the IC chip  26  uses a contactless communication system in which data are transmitted and received from the antenna unit  19  via the loop antenna  4  shown in  FIG. 1 . The antenna unit  19  also supplies power received via the loop antenna  4  to the IC chip  26 . The input-output controller  20  controls the input and output of data received and transmitted from the antenna unit  19 . The first access controller  21  and second access controller  22  control access to the data stored in the IC chip  26 . The comparison unit  23  decides whether access to the data stored in the IC chip  26  is authorized or not. The first memory  24  and second memory  25  are both nonvolatile memories permitting read and write access, and the first memory  24  permits repeated write access. Authentication data used in decision making by the comparison unit  23  are stored in the first memory  24 ; the authentication data include both prestored authentication data and additional data transmitted and received as described above; validation data transmitted and received as described above are stored in the second memory  25 .  
         [0054]     The printing medium  1  incorporating the IC chip  26  in the second embodiment may be used for various purposes. To address the problems of the prior art described above, as in the first embodiment, it will be assumed that the printing medium  1  is used for printing a negotiable security. Repeated descriptions of the image forming apparatus will be omitted, since this apparatus was described in the first embodiment.  
         [0055]     To make the printing medium  1  shown in  FIG. 1  into a negotiable security incorporating the IC chip  26  in the second embodiment, two processes must be performed: first, the title and other information of the security must be printed on the printing medium  1 , and second, information that can certify the validity of the printing medium  1  when it is used as a negotiable security must be stored in the second memory  25  of the IC chip  26  as validation data. The validity of the negotiable security is verified by comparing the information printed on the printing medium  1  with the validation data stored in the second memory  25 .  
         [0056]     The validation data are stored in the second memory  25  when an image is printed on the printing medium  1 , to certify the validity of the image printed on the printing medium  1 . As in the first embodiment, it is assumed that the information printed on the printing medium  1  includes at least the price of the negotiable security, and that the price data are used as validation data. In practice, the validation data may be any data that can be compared with the image printed on the printing medium  1  to verify the image. Instead of price data, the validation data may be, for example, issuer data, owner data, or issue date data, or an encrypted form of any of these data.  
         [0057]     To write the validation data when the external device  12  requests printing of the negotiable security by sending the printing data, the comparison unit  23  first decides whether to permit write access to the second memory  25 . If write access is permissible, the input-output controller  20  transfers additional data received via the antenna unit  19  to the first access controller  21 , and transfers validation data, also received via the antenna unit  19 , to the second access controller  22 . The first access controller  21  writes the additional data into the first memory  24 , appending the additional data to the authentication data already stored in the first memory  24 ; the second access controller  22  writes the validation data into the second memory  25 . If write access is not permissible, the additional data and validation data are not received and written.  
         [0058]     The authentication data prestored in the first memory  24  are used to decide whether these write accesses to the first and second memories  24 ,  25  are permissible. These authentication data are prestored in the first memory  24  before the IC chip  26  is attached to the printing medium  1 , and do not include the additional authentication data appended later. The prestored authentication data may be any data associated with the printing medium  1 , such as data identifying the manufacturer of the IC chip  26 , data identifying the security issuer who performs printing on the printing medium  1 , data identifying the media type of the printing medium  1 , or serial number data. In this second embodiment, as in the first embodiment, data identifying the media type of the printing medium  1  (media data) are employed as the prestored authentication data.  
         [0059]     To read the validation data when the external device  12  requests reading of data to verify the authenticity of the negotiable security, the comparison unit  23  first decides whether read access to the validation data stored in the second memory  25  is permissible. If read access is permissible, the second access controller  22  reads the validation data from the second memory  25  and transfers the validation data to the input-output controller  20 , which transmits the transferred data via the antenna unit  19 . If read access is not permissible, reading and transmitting of the validation data are not carried out.  
         [0060]     Both the authentication data prestored in the first memory  24  and the additional data appended to the prestored authentication data are used to decide whether the above read access is possible or not. The additional data appended to the prestored authentication data may be any data associated with the printing medium  1  or the image printed on the printing medium  1 , such as data identifying the manufacturer of the IC chip  26 , data identifying the security issuer who performs printing on the printing medium  1 , data identifying the media type of the printing medium  1 , data identifying the owner of the image printed on the printing medium  1  or a person having right of access thereto, or serial number data. In the description below, data identifying the owner of the image printed on the printing medium  1  or a person having right of access thereto (authorization data) are employed as the additional data.  
         [0061]     As described above, the authenticity of the negotiable security in the second embodiment is verified as in the first embodiment, by reading the validation data stored in the second memory  25 , but the decision as to whether to permit read access to the second memory  25  is made on the basis of both the authentication data prestored in the first memory  24  and the authorization data appended as additional authentication data when the negotiable security was printed on the printing medium  1 . In the second embodiment, therefore, a person attempting to perform read access must be in possession of both the prestored authentication data (in this case, media data) and the additional data (in this case, authorization data).  
         [0062]     The controller  14  in the image forming apparatus  11 , shown in  FIGS. 3 and 4 , receives printing data from the input-output unit  13 , and converts the received printing data into image data to be printed on the printing medium  1 , authorization data to be additionally stored in the first memory  24 , and security price data to be stored in the second memory  25 . The communication unit  16  transmits both the authorization data and the security price data to the IC chip  26 . Aside from these differences, the image forming apparatus  11  operates as described in the first embodiment.  
         [0063]     The flowcharts in  FIGS. 5A and 5B , which illustrate the printing of an image and writing of data in the first embodiment, also describe the printing and writing operations in the second embodiment, because these operations are the same as in the first embodiment, except for modifications made necessary by the authorization data. The modifications will be explained in the description below.  FIG. 5A  shows operations performed by the image forming apparatus  11 ;  FIG. 5B  shows operations performed by the IC chip  26 .  
         [0064]     First, the controller  14  in the image forming apparatus  11  receives printing data from the external device  12  via the input-output unit  13  (step  101  in  FIG. 5A ). While pre-feeding the printing medium  1 , the controller  14  converts the received printing data by executing an embedded program to generate image data to be printed on the printing medium  1  and price data to be sent to the printing medium  1  (step  102 ).  
         [0065]     After completion of the above data conversion, the controller  14  requests the entry on the operation panel  15  of comparison data necessary for authorization of write access to the first memory  24  and second memory  25 , and sends the entered comparison data to the printing medium  1  via the communication unit  16  (step  103 ).  
         [0066]     The IC chip  26  transfers the above comparison data, which are received via the antenna unit  19 , to the comparison unit  23  via the input-output controller  20  (step  111  in  FIG. 5B ). The comparison unit  23  compares the received comparison data with the authentication data (media data) prestored in the first memory  24 , and decides from the comparison result whether to permit data to be written into the second memory  25  (step  112 ). If the comparison result indicates that the comparison data match the authentication data, the comparison unit  23  sends a write access permission signal through the input-output controller  20  and antenna unit  19  to notify the image forming apparatus  11  that writing of data is possible, while sending the same notification to the first access controller  21  and second access controller  22  in the IC chip  26  (step  113 ). If the comparison result indicates that the comparison and authentication data do not match, the comparison unit  23  sends a write access denial signal through the input-output controller  20  and antenna unit  19  to notify the image forming apparatus  11  that writing of data is not possible (step  114 ).  
         [0067]     The communication unit  16  in the image forming apparatus  11  receives the comparison result sent from the IC chip  26  and transfers it to the controller  14  (step  104  in  FIG. 5A ), which decides from the comparison result whether data can be written or not (step  105 ). If the comparison result indicates that data can be written, the controller  14  controls the image forming unit  17  to print the image data on the pre-fed printing medium  1 , and sends the authorization data and price data to the printing medium  1  via the communication unit  16  (step  106 ). If the above comparison result indicates that data cannot be written, the controller  14  returns the pre-fed printing medium  1  to the printer tray without printing (step  107 ).  
         [0068]     If the IC chip  26  sends a write access permission signal (in step  113  in  FIG. 5A ), the above authorization data and price data, which are received via the antenna unit  19 , are sent to the first access controller  21  and second access controller  22 , respectively, via the input-output controller  20  (step  115 ). The first access controller  21  writes the authorization data into the first memory  24 ; the second access controller  22  writes the price data into the second memory  25  (step  116 ). If the IC chip  26  sends a write access denial signal (in step  114 ), no data are written into the first memory  24  and second memory  25 .  
         [0069]     The flowcharts in  FIGS. 6A and 6B , which illustrate the reading of data in the first embodiment, also illustrate the reading operation in the second embodiment because the reading operation is the same as in the first embodiment except for modifications made necessary by the authorization data. These modifications will be explained in the description below.  FIG. 6A  shows operations performed by the image forming apparatus  11 ;  FIG. 6B  shows operations performed by the IC chip  26 .  
         [0070]     First, the controller  14  in the image forming apparatus  11  receives a read request from the external device  12  via the input-output unit  13  (step  201  in  FIG. 6A ). The controller  14  then executes an embedded program that causes the operation panel  15  to display a prompt for entry of the comparison data necessary to authorize the reading of data from the second memory  25 . After the operator of the image forming apparatus  11  enters the comparison data, the controller  14  sends the comparison data to the printing medium  1  via the communication unit  16 , while pre-feeding the printing medium  1  (step  202 ). The entered comparison data must include both the prestored authentication data and the additional authorization data.  
         [0071]     The IC chip  26  attached to the pre-fed printing medium  1  transfers the comparison data received via the antenna unit  19  to the comparison unit  23  via the input-output controller  20  (step  211  in  FIG. 6B ). The comparison unit  23  compares the received comparison data with the data (including the authorization data) stored in the first memory  24 , and decides from the comparison result whether data can be read from the second memory  25  nor not (step  212 ). If the comparison result indicates that the comparison data match the authentication data and additional data stored in the first memory  24 , the comparison unit  23  sends a read access permission signal to the second access controller  22 , and to the image forming apparatus  11  via the input-output controller  20  and antenna unit  19 , indicating that data can be read (step  213 ). If the comparison result indicates that the comparison data and stored data do not match, the comparison unit  23  sends a read access denial signal to the image forming apparatus  11  via the input-output controller  20  and antenna unit  19 , indicating that data cannot be read (step  214 ). When data can be read, the second access controller  22  reads the price data stored in the second memory  25  and transfers the price data to the input-output controller  20 , which sends the transferred price data to the image forming apparatus  11  via the antenna unit  19  (step  215 ).  
         [0072]     In the image forming apparatus  11 , the comparison result sent from the IC chip  26  is received by the communication unit  16  and transferred to the controller  14  (step  203  in  FIG. 6A ). The controller  14  then decides from the comparison result whether reading of data is permissible or not (step  204 ). If the comparison result indicates that reading of data is permissible, the controller  14  receives the price data sent from the IC chip  26  of the pre-fed printing medium  1  via the communication unit  16 , converts the price data to data that can be displayed on the operation panel  15  by executing an embedded program, displays the converted data on the operation panel  15  (step  205 ) and ejects the pre-fed printing medium  1  (step  206 ). If the comparison result indicates that reading of data is not permissible, the controller  14  displays an error message and ejects the pre-fed printing medium  1  (step  206 ).  
         [0073]     As described above, the second embodiment provides a further degree of protection against counterfeiting by requiring the counterfeiter to know two types of data (authentication data and authorization data) that cannot be read from the IC chip  26 . In particular, the authorization data can be uniquely determined by the person who operates the input-output unit  13  when the original negotiable security is printed on the printing medium  1 , making it very difficult for the counterfeiter to determine what the authorization data are.  
         [0074]     In the first and second embodiments, the communication region  18  in which the image forming apparatus  11  and printing medium  1  can communicate with each other is located in the area into which the printing medium  1  is pre-fed, but the communication region  18  may be located anywhere, provided the location enables the image forming apparatus  11  to reliably distinguish the printing medium  1  with which it wants to communicate from other printing media stacked in the printer tray. The IC chip may also be mounted anywhere on the printing medium  1  as long as the IC chip is located in the communication region  18  during the time when communication must take place.  
         [0075]     The above embodiments have been described in relation to the printing of a negotiable security, but the present invention can also be practiced with other matter printed on printing media that can store electronic data, especially if the printed matter is printed, read, and written exclusively by a particular administrative organization. Such printed matter includes various kinds of certificates and tickets, business documents such as contracts and applications, and copyright matter using paper media such as posters and compact disc (CD) jackets  
         [0076]     Those skilled in the art will recognize that further variations are possible within the scope of the invention, which is defined in the appended claims.