JP2006059385A - Data reproducing system, data writer and data reader for use in the same, and method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce data recorded in a memory card by managing a reproduction time limit. <P>SOLUTION: A data reader 300 includes: a memory card interface 344 communicating with a memory card in which data such as video, the recorded date of that data, and a reproduction time limit of that data are recorded; a real time clock 330 detecting the current date; a display unit 352 reading out data from the memory card to display video or the like; and a CPU 320 comparing the current date detected by the real time clock 330 with the recorded date and reproduction time limit of the data recorded in the memory card 200 to determine whether reproduction of the data recorded in the memory card 200 is allowed or not. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for reproducing digital data only within a reproduction deadline, and in particular, in a reproduction apparatus including a circuit for detecting the current time, the reproduction deadline for digital data is detected by detecting that the current time has been illegally changed. Relating to the technology to strictly manage.

  With the recent development of digital technology, there are cases where a user reproduces image data and music data stored in a recording medium using digital data using a reproducing apparatus. When image data and music data are rented, the user can play back images and music using the playback device within a preset playback time limit. Playback is managed based on the time detected by the user's playback device and playback time limit information written when digital data is stored in the recording medium. If the current time detected by the user's playback device is altered, the content can be played back even though the playback deadline has passed. Management of the time detected by the user's playback device is important.

  Japanese Patent Laying-Open No. 8-235402 (Patent Document 1) discloses a time recorder for detecting subtle tampering of time. The time recorder disclosed in this publication is a time recorder that performs time management based on the time of an internal clock. The time recorder includes a first detection circuit that detects time with high accuracy, a second detection circuit that detects time with lower accuracy than the first detection circuit, and a time detected by the second detection circuit. A circuit for storing the attendance data indicating the attendance time and the attendance time, and a calculation circuit for calculating a time difference between the first detection circuit and the second detection circuit each time the attendance data is input. It includes a determination circuit that determines whether or not the absolute value of the time difference is greater than or equal to the reference time, and a storage circuit that stores a change history if the time difference is greater than or equal to the reference time.

In the first detection circuit, the time is set only by the administrator. When an error occurs in the time, the second detection circuit is corrected to the time detected by the first detection circuit by a person other than the administrator. This time recorder is provided with two detection circuits for detecting time, and based on the time detected by the first detection circuit having high detection accuracy, calculates a time difference and determines whether or not there is a time change. As a result, when the time detected by the second detection circuit is falsified more than the reference time while minimizing the influence of the error of the internal clock, the change history is stored.
JP-A-8-235402

  However, this time recorder requires a first detection circuit that detects the time with high accuracy. Since such a first detection circuit is expensive, the time recorder is expensive. By using such a first detection circuit, the time can be strictly managed in a reproducing apparatus that reproduces digital data, but the reproducing apparatus becomes expensive.

  The present invention has been made to solve the above-described problems, and can be realized at low cost. A data reproduction system for managing reproduction deadlines and outputting digital data, a data writing device used in the system, and a data reading It is to provide a device, a data writing method and a data reading method in these devices.

  A data reproduction system according to a first aspect is a system in which data written on a recording medium by a data writing device is read by a data reading device. The data writing device includes a storage unit for storing data, a detection unit for detecting date and time, a setting unit for setting a time limit for outputting data by the data reading device, a storage unit and a detection unit, And a writing unit connected to the setting unit and for writing the data, the time limit, and the data and the writing date and time of the time limit detected by the detecting unit on the recording medium. The data reader is connected to a detecting means for detecting the current date and time, a reading means for reading the time limit and the writing date and time from the recording medium, a detecting means and a reading means of the data reading device, When it is connected to a judging means for judging whether or not data written on the recording medium can be output based on the writing date and time and the current date and time, and the reading means and the judging means are connected and data can be output. Output means for reading and outputting data from the recording medium.

  According to the first invention, the data writing device sets a time limit during which data can be output by the data reading device, and writes the data, the time limit, the data to the recording medium, and the writing date and time of the time limit on the recording medium. . The data reader determines whether or not the data written to the recording medium can be output based on the time limit read from the recording medium, the writing date and time, and the detected current date and time, and can output the data. The data is read from the recording medium and output. It is assumed that the time limit for outputting data has passed and the current date and time detected by the detection means of the data reader is changed before the writing date and time and data is illegally output. In this case, since the current date and time changed illegally is before the date and time when the data was written, the determination unit does not determine that the data can be output. As a result, a data reproduction system that manages the reproduction time limit and outputs digital data can be provided at low cost.

  In addition to the configuration of the first invention, the data reading device in the data reproduction system according to the second invention is connected to the detecting means of the data reading device, and overwrites the current date and time with the writing date and time written on the recording medium. In addition, overwriting means is included.

  According to the second invention, the current date and time are overwritten by the overwriting means on the writing date and time written on the recording medium. Assume that the time limit for outputting data has passed and the current date and time detected by the detection means of the data reader has been changed illegally. Until the time limit for data output elapses, the normal current date and time are detected, and the correct current date and time are written in the recording date and time of the recording medium. Even if you attempt to output data illegally by changing the current date and time after the expiration date to a date and time within the expiration date, the current date and time will be before the date and time when the data was written (the date and time overwritten with the correct current date and time) Therefore, the determination unit does not determine that data can be output. As a result, a data reproduction system that manages the reproduction time limit and outputs digital data can be provided at low cost.

  In the data reading device in the data reproduction system according to the third invention, in addition to the configuration of the first or second invention, the judging means may determine that the current date is after the writing date and before the deadline. And means for determining that the data written in the recording medium can be output.

  According to the third invention, the determining means determines that the data written in the recording medium can be output when the current date and time is after the writing date and before the expiration date. As a result, if the current date and time detected by the detection means of the data reader is not illegally changed and the current date and time is within the time limit for outputting data, the data written on the recording medium can be output. To be judged.

  According to a fourth aspect of the present invention, there is provided the data reading device in the data reproduction system. Means for detecting the time, and means for detecting the current date and time based on the output start date and time and the elapsed time are included.

  According to the fourth aspect of the present invention, it is assumed that the current date and time is changed illegally after the start of data output. Even in this case, the current time detected by the detecting means of the data reader is calculated by adding the elapsed time from the output start date and time to the data output start date and time. Thereby, even if the current date and time is changed illegally after the start of data output, the correct current time can be calculated.

  In addition to the configuration of the first invention, the data reading device in the data reproduction system according to the fifth invention is for detecting that the current date is incorrect if the current date is earlier than the writing date. An error date detection means is further included.

  According to the fifth invention, the erroneous date detection means detects that the current date is incorrect if the current date is earlier than the writing date. By detecting that the current date and time are incorrect, it is possible to detect that the current time of the data reading device has been illegally changed by the user.

  In addition to the configuration of the fifth invention, the data reading device in the data reproduction system according to the sixth invention is connected to the erroneous date detection means, and when the current date is detected to be incorrect, Further included is a processing means for making the reading of the data impossible.

  According to the sixth aspect, when it is detected that the current date and time are incorrect, the processing means performs a process of making it impossible to read data from the recording medium. As a result, if the user of the data reader performs an illegal act, all data written on the recording medium is erased.

  In addition to the configuration of the first invention, the data reading device in the data reproduction system according to the seventh invention is connected to the detecting means of the data reading device, and the current date and time detected by the detecting means of the data reading device is the management date and time. Further includes management date storage means for storing as. The determining means includes means for determining whether or not the data written on the recording medium can be output based on the time limit, the writing date and time, the management date and time, and the current date and time.

  According to the seventh aspect, the data reader stores the management date and time. The management date / time is the current date / time detected by the detection means of the data reader. For example, when the current date is after the writing date, after the management date, and before the deadline, the determining unit determines that the data written in the recording medium can be output. If the current date / time is illegally changed after the write date / time, before the management date / time and before the deadline, and the data is output illegally, the current date / time is before the management date / time. Therefore, the determination unit does not determine that data can be output.

  In addition to the configuration of the seventh invention, the data reading apparatus in the data reproduction system according to the eighth invention is characterized in that the determination means has the current date and time after the writing date and time, after the management date and time, and before the time limit Means for determining that the data written in the recording medium can be output.

  According to the eighth aspect of the present invention, even if an attempt is made to illegally change the current date and time after the writing date and time to a date and time before the management date, Therefore, the determination unit does not determine that data can be output.

  In addition to the configuration of the eighth invention, the data reading device in the data reproduction system according to the ninth invention is for detecting that the current date is incorrect if the current date is earlier than the management date. An error date detection means is further included.

  According to the ninth aspect, the erroneous date detection means detects that the current date is incorrect if the current date is earlier than the management date. By detecting that the current date and time are incorrect, it is possible to detect that the current time of the data reading device has been illegally changed by the user.

  A data writing apparatus according to a tenth aspect of the invention is used in a data reproduction system in which data written on a recording medium by a data writing apparatus is read by a data reading apparatus. The data reader determines whether or not the data written to the recording medium can be output based on the time limit read from the recording medium, the writing date and time, and the detected current date and time, and can output the data. The data is read from the recording medium and output. The data writing device includes a storage unit for storing data, a detection unit for detecting date and time, a setting unit for setting a time limit for outputting data by the data reading device, a storage unit and a detection unit, And a writing unit connected to the setting unit and for writing the data, the time limit, and the data and the writing date and time of the time limit detected by the detecting unit on the recording medium.

  According to the tenth aspect, the data writing device sets a time limit during which data can be output by the data reading device, and writes the data, the time limit, the data to the recording medium, and the writing date and time of the time limit on the recording medium. . The data reader determines whether or not the data written to the recording medium can be output based on the time limit read from the recording medium, the writing date and time, and the detected current date and time, and can output the data. The data is read from the recording medium and output. It is assumed that the time limit for outputting data has passed and the current date and time detected by the detection means of the data reader is changed before the writing date and time and data is illegally output. In this case, since the current date and time changed illegally is before the date and time when the data was written, the determination unit does not determine that the data can be output. As a result, it is possible to inexpensively provide a data writing device used in a data reproduction system that manages reproduction deadlines and outputs digital data.

  A data reader according to an eleventh aspect of the invention is used in a data reproduction system in which data written on a recording medium by a data writing device is read by the data reading device. The data writing device sets a time limit during which data can be output by the data reading device, and writes the data, the time limit, the data to the recording medium, and the writing date and time of the time limit on the recording medium. The data reader is connected to a detecting means for detecting the current date and time, a reading means for reading the time limit and the writing date and time from the recording medium, a detecting means and a reading means of the data reading device, When it is connected to a judging means for judging whether or not data written on the recording medium can be output based on the writing date and time and the current date and time, and the reading means and the judging means are connected and data can be output. Output means for reading and outputting data from the recording medium.

  According to the eleventh aspect, the data writing device sets a time limit during which data can be output by the data reading device, and writes the data, the time limit, the data to the recording medium, and the writing date and time of the time limit on the recording medium. . The data reader determines whether or not the data written to the recording medium can be output based on the time limit read from the recording medium, the writing date and time, and the detected current date and time, and can output the data. The data is read from the recording medium and output. It is assumed that the time limit for outputting data has passed and the current date and time detected by the detection means of the data reader is changed before the writing date and time and data is illegally output. In this case, since the current date and time changed illegally is before the date and time when the data was written, the determination unit does not determine that the data can be output. As a result, it is possible to inexpensively provide a data reader used in a data reproduction system that manages reproduction deadlines and outputs digital data.

  The data reader according to the twelfth invention is added to the configuration of the eleventh invention, connected to the detection means of the data reader, and overwrites the date and time written on the recording medium for overwriting the current date and time. Means are further included.

  According to the twelfth aspect, the current date and time are overwritten by the overwriting means on the writing date and time written on the recording medium. Assume that the time limit for outputting data has passed and the current date and time detected by the detection means of the data reader has been changed illegally. Until the time limit for data output elapses, the normal current date and time are detected, and the correct current date and time are written in the recording date and time of the recording medium. Even if you change the current date and time after the expiration date to a date that is within the expiration date and try to output data illegally, the current date and time is before the date and time when the data was written (the date and time overwritten by the correct current date and time) Therefore, the determination unit does not determine that data can be output. As a result, it is possible to inexpensively provide a data reader used in a data reproduction system that manages reproduction deadlines and outputs digital data.

  In addition to the configuration of the eleventh or twelfth invention, the data reading device according to the thirteenth invention is characterized in that the judging means stores the current date and time on the recording medium after the writing date and time and before the deadline. Means for determining that the written data can be output are included.

  According to the thirteenth aspect, the determining means determines that the data written on the recording medium can be output if the current date is after the writing date and before the expiration date. As a result, if the current date and time detected by the detection means of the data reading device is not illegally changed and the current date and time is within the time limit for outputting data, the data reading that can output the data written on the recording medium Equipment can be provided.

  In addition to the structure of the eleventh invention, the data reading device according to the fourteenth invention is configured to detect a data output start date and time, and an elapsed time from the output start date and time. And means for detecting the current date and time based on the output start date and time and the elapsed time.

  According to the fourteenth invention, it is assumed that the current date and time is changed illegally after the start of data output. Even in this case, the current time detected by the detecting means of the data reader is calculated by adding the elapsed time from the output start date and time to the data output start date and time. As a result, it is possible to provide a data reader that can calculate the correct current time even if the current date and time are changed illegally after the start of data output.

  In addition to the configuration of the eleventh invention, the data reading device according to the fifteenth invention is an erroneous date detection means for detecting that the current date is incorrect if the current date is earlier than the writing date. Further included.

  According to the fifteenth aspect, the erroneous date detection means detects that the current date is incorrect if the current date is earlier than the writing date. By detecting that the current date and time are incorrect, it is possible to provide a data reader that can detect that the current time of the data reader has been illegally changed by the user.

  In addition to the configuration of the fifteenth aspect of the invention, the data reader according to the sixteenth aspect of the invention is connected to the erroneous date / time detecting means, and when it is detected that the current date / time is incorrect, the data reading device reads the data from the recording medium. It further includes processing means for making it impossible.

  According to the sixteenth aspect, when it is detected that the current date and time are incorrect, the processing means performs a process of making it impossible to read data from the recording medium. Thereby, when the user of the data reader performs an illegal act, it is possible to provide a data reader in which all data written on the recording medium is erased.

  In addition to the structure of the eleventh invention, a data reader according to the seventeenth invention is connected to the detection means of the data reader and stores the current date and time detected by the detection means of the data reader as the management date and time. The management date storage means is further included. The determining means includes means for determining whether or not the data written on the recording medium can be output based on the time limit, the writing date and time, the management date and time, and the current date and time.

  According to the seventeenth aspect, the data reader stores the management date and time. The management date / time is the current date / time detected by the detection means of the data reader. For example, when the current date is after the writing date, after the management date, and before the deadline, the determining unit determines that the data written in the recording medium can be output. If the current date / time is illegally changed after the write date / time, before the management date / time and before the deadline, and the data is output illegally, the current date / time is before the management date / time. Therefore, the determination means can provide a data reader that does not determine that data can be output.

  In addition to the configuration of the seventeenth invention, in the data reading device according to the eighteenth invention, the determination unit may determine that the current date and time is after the writing date and time, after the management date and time, and before the deadline. Means for determining that the data written in the recording medium can be output are included.

  According to the eighteenth aspect of the present invention, even if an attempt is made to illegally change the current date and time after the writing date and time to a date and time earlier than the management date and to output data illegally, the current date and time is before the management date and time. Therefore, the determination means can provide a data reader that does not determine that data can be output.

  In addition to the configuration of the eighteenth invention, the data reading device according to the nineteenth invention is an erroneous date detection means for detecting that the current date is incorrect if the current date is earlier than the management date. Further included.

  According to the nineteenth aspect, the erroneous date detection means detects that the current date is incorrect if the current date is earlier than the management date. By detecting that the current date and time are incorrect, it is possible to provide a data reader that can detect that the current time of the data reader has been illegally changed by the user.

  A data writing method according to a twentieth aspect of the invention is a method in a data writing device used in a data reproducing system for reading data written on a recording medium by a data writing device by a data reading device. The data reader determines whether or not the data written to the recording medium can be output based on the time limit read from the recording medium, the writing date and time, and the detected current date and time, and can output the data. The data is read from the recording medium and output. A data writing method includes a preparation step for preparing data, a detection step for detecting date and time, a setting step for setting a time limit for outputting data by a data reading device, data, a time limit, and a recording medium on a recording medium And a writing step for writing the data and the date and time of writing.

  According to the twentieth invention, in the setting step, a time limit for outputting data by the data reader is set. In the writing step, the data, the time limit, the data to the recording medium, and the writing date and time of the time limit are written on the recording medium. The data reader determines whether or not the data written to the recording medium can be output based on the time limit read from the recording medium, the writing date and time, and the detected current date and time, and can output the data. The data is read from the recording medium and output. It is assumed that the time limit for outputting data has passed and the current date and time detected by the detection means of the data reader is changed before the writing date and time and data is illegally output. In this case, since the current date and time changed illegally is before the date and time when the data was written, the data reader does not determine that the data can be output. As a result, it is possible to provide a low-cost data writing method in a data writing device used in a data reproduction system that manages reproduction deadlines and outputs digital data.

  A data reading method according to a twenty-first aspect of the invention is a method in a data reading device used in a data reproduction system in which data written on a recording medium by a data writing device is read by the data reading device. The data writing device sets a time limit during which data can be output by the data reading device, and writes the data, the time limit, the data to the recording medium, and the writing date and time of the time limit on the recording medium. The data reading method is written to the recording medium based on the detection step for detecting the current date and time, the reading step for reading the expiration date and the writing date and time from the recording medium, the expiration date, the writing date and time, and the current date and time. A determination step for determining whether or not data can be output; and an output step for reading and outputting the data from the recording medium when the data can be output.

  According to the twenty-first aspect, the data writing device sets a time limit during which data can be output by the data reading device, and writes the data, the time limit, the data to the recording medium, and the writing date and time of the time limit on the recording medium. . In the reading step, the time limit and the writing date / time are read from the recording medium, and in the determining step, it is determined whether the data written in the recording medium can be output based on the time limit, the writing date / time and the detected current date / time. Is done. If data can be output in the output step, the data is read from the recording medium and output. It is assumed that the time limit for outputting data has passed and the current date and time detected by the detection means of the data reader is changed before the writing date and time and data is illegally output. In this case, since the current date and time changed illegally is before the date and time when the data was written, it is not determined that the data can be output in the determination step. As a result, it is possible to provide a data reading method at a low cost in a data reading apparatus used in a data reproduction system that manages reproduction deadlines and outputs digital data.

  In addition to the structure of the twenty-first invention, the data reading method according to the twenty-second invention further includes an overwriting step of overwriting the current date and time on the writing date and time written on the recording medium.

  According to the twenty-second aspect, the current date and time are overwritten in the overwriting step on the writing date and time written on the recording medium. A case is assumed where the current date and time of the data reader has been illegally changed after the time limit for outputting data has passed. Until the time limit for data output elapses, the normal current date and time are detected, and the correct current date and time are written in the recording date and time of the recording medium. Even if you change the current date and time after the expiration date to a date that is within the expiration date and try to output data illegally, the current date and time is before the date and time when the data was written (the date and time overwritten by the correct current date and time) Therefore, it is not determined that data can be output in the determination step. As a result, it is possible to provide a data reading method at a low cost in a data reading apparatus used in a data reproduction system that manages reproduction deadlines and outputs digital data.

  In the data reading method according to the twenty-third invention, in addition to the configuration of the twenty-first or twenty-second invention, in the determination step, if the current date and time is after the writing date and time and before the deadline, Determining that the written data can be output.

  According to the twenty-third aspect, in the determination step, it is determined that the data written to the recording medium can be output if the current date is after the writing date and before the expiration date. Thus, it is possible to provide a data reading method capable of outputting the data written in the recording medium when the current date and time of the data reading device is not changed illegally and the current date and time is within the time limit for outputting the data.

  In the data reading method according to the twenty-fourth invention, in addition to the structure of the twenty-first invention, the detecting step includes a step of detecting a date and time of starting output of data, and a step of detecting an elapsed time from the date and time of starting output. And a step of detecting the current date and time based on the output start date and time and the elapsed time.

  According to the twenty-fourth invention, it is assumed that the current date and time are changed illegally after the start of data output. Even in this case, the current time of the data reader is calculated by adding the elapsed time from the output start date and time to the data output start date and time. Thus, it is possible to provide a data reading method capable of calculating the correct current time even if the current date and time are changed illegally after the start of data output.

  In addition to the structure of the twenty-first aspect, the data reading method according to the twenty-fifth aspect of the invention further comprises an erroneous date detection step of detecting that the current date is incorrect if the current date is earlier than the writing date. Including.

  According to the twenty-fifth aspect, in the erroneous date detection step, if the current date is earlier than the writing date, it is detected that the current date is incorrect. By detecting that the current date and time are incorrect, it is possible to provide a data reading method capable of detecting that the current time of the data reading device has been illegally changed by the user.

  In addition to the configuration of the twenty-fifth invention, the data reading method according to the twenty-sixth invention further includes a processing step for making it impossible to read data from the recording medium when it is detected that the current date is incorrect. Including.

  According to the twenty-sixth aspect, when it is detected that the current date and time are incorrect, processing for making it impossible to read data from the recording medium is performed in the processing step. Thus, it is possible to provide a data reading method in which all data written on the recording medium is erased when the user of the data reading device performs an illegal act.

  In addition to the structure of the twenty-first aspect, the data reading method according to the twenty-seventh aspect of the invention further includes a management date and time storage step of storing the current date and time detected in the detection step as the management date and time. The determining step includes a step of determining whether or not the data written on the recording medium can be output based on the time limit, the writing date and time, the management date and time, and the current date and time.

  According to the twenty-seventh aspect, the management date is stored in the management date storage step. The management date / time is the current date / time detected in the detection step. In the determination step, for example, if the current date and time is after the writing date and time, after the management date and time, and before the deadline, it is determined that the data written on the recording medium can be output. If the current date / time is illegally changed after the write date / time, before the management date / time and before the deadline, and the data is output illegally, the current date / time is before the management date / time. Therefore, it is possible to provide a data reading method that does not determine that data can be output in the determination step.

  In the data reading method according to the twenty-eighth aspect of the invention, in addition to the configuration of the twenty-seventh aspect of the invention, in the determination step, the current date and time is after the writing date and time, after the management date and time, and before the deadline. Determining that the data written to the recording medium can be output.

  According to the twenty-eighth aspect of the present invention, even if an attempt is made to illegally change the current date and time to a date before and after the writing date and before the management date, Therefore, it is possible to provide a data reading method that does not determine that data can be output in the determination step.

  In addition to the configuration of the twenty-eighth invention, the data reading method according to the twenty-ninth invention further includes an erroneous date detection step for detecting that the current date is incorrect if the current date is earlier than the management date. Including.

  According to the twenty-ninth aspect, in the erroneous date detection step, if the current date is earlier than the management date, it is detected that the current date is incorrect. By detecting that the current date and time are incorrect, it is possible to provide a data reading method capable of detecting that the current time of the data reading device has been illegally changed by the user.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
Referring to FIG. 1, the data reproduction system according to the present embodiment includes a data writing device 100 that writes data to memory card 200, a data reading device 300 that reads data from memory card 200, and data writing device 100. A data distribution server 400 that transmits data, and a network 500 that connects the data writing device 100 and the data distribution server 400 are included.

  Data writing device 100 temporarily stores data representing images, videos, and music received from data distribution server 400. The data writing device 100 writes the temporarily stored data into the memory card 200 in accordance with a user request. The data writing device 100 is installed in a place where many people gather, such as a station premises and a convenience store.

  The data reader 300 is installed in a user's home, for example. The data reading device 300 reads data written on the memory card 200 by the user using the data writing device 100. The data reader 300 outputs an image, video, and music based on the data read from the memory card 200.

  The memory card 200 is a recording medium that can be carried by a user. For example, a card-shaped recording medium using a semiconductor memory.

  The data distribution server 400 stores a large amount of data representing images, videos, and music. The data distribution server 400 distributes the data to the plurality of data writing devices 100 via the network 500.

  With reference to FIG. 2, the structure of data writing apparatus 100 according to the present embodiment will be described. As shown in FIG. 2, the data writing device 100 includes a storage unit 110 that stores various data, a real-time clock 130 that detects the current date and time, an interface unit 140 that communicates with external devices, and user operations. An input / output unit 150 for inputting and outputting data, and a CPU (Central Processing Unit) 120 that is connected to the storage unit 110, the real-time clock 130, the interface unit 140, and the input / output unit 150 and controls the data writing device 100. Including.

  The storage unit 110 stores a ROM (Read Only Memory) 112 that stores a program for controlling the data writing device 100, a secret key for decrypting digital data representing images, video, and music, and the like. A random access memory (RAM) 114 that stores data in the middle of execution of the program, and a nonvolatile memory 116 that stores data representing images, video, and music received from the data distribution server 400. The ROM 112 stores a plurality of secret keys. The RAM 114 stores a relationship between a secret key and a user ID (identification). The user ID is identification information selected by the data writing device 100 in order to uniquely identify a user in this data reproduction system.

  The interface unit 140 includes a network interface 142 for receiving data from the data distribution server 400 connected to the network 500, and a memory card interface 144 connected to the memory card 200 and communicating with the memory card 200. A memory card 200 is set in the memory card interface 144. The memory card interface 144 reads data from the memory card 200 or writes data to the memory card 200 based on an instruction from the CPU 120.

  The input / output unit 150 displays a list of data representing images, videos, and music stored in the non-volatile memory 116, displays an operation procedure, and displays the data displayed on the display unit 152. And an operation unit 154 for performing an operation of selecting data to be written to the memory card 200 from the list. The user performs initial setting of the memory card according to the operation procedure displayed on the display unit 150.

  With reference to FIG. 3, the structure of data reading apparatus 300 according to the present embodiment will be described. As shown in FIG. 3, the data reading device 300 includes a memory card interface 344 instead of the interface unit 140 of the data writing device 100 described above. The data reading device 300 includes an audio output unit 356 in addition to the configuration of the input / output unit 150 of the data writing device 100 described above.

  The memory card interface 344 is the same as the memory card interface 144 described above. The sound output unit 356 outputs sound based on the digital data stored in the memory card 200.

  The ROM 112 and the RAM 314 shown in FIGS. 2 and 3 store a secret key for decrypting the digital data used in this data reproduction system. The RAM 114 and RAM 314 store the relationship between the user ID and the secret key and the user ID. The nonvolatile memory 316 of the data reader 300 stores the current date and time detected by the real time clock 330. This stored current date and time is referred to as the latest time of the data reader.

  The structure of the memory card 200 will be described with reference to FIG. As shown in FIG. 4, the memory card 200 includes a memory card interface 202 and a RAM 204 connected to the memory card interface 202. The memory card interface 202 communicates with the data writing device 100 or the data reading device 300 via the memory card interface 144 or the memory card interface 344, respectively.

  The data stored in the RAM 204 shown in FIG. 4 will be described with reference to FIG. As shown in FIG. 5, the data stored in the memory card 200 includes a secret key, a reproduction key encrypted with the secret key, and user data. In this data reproduction system, encryption processing by DES (Data Encryption Standard) is used.

  The user data includes the latest time indicating the current date and time detected by the real-time clock 130 of the data writing device 100, management information, and digital data encrypted by the reproduction key. The latest time stored in the memory card 200 is referred to as the latest time of the memory card. The management information includes information corresponding to the type of digital data stored in the user data. For example, it is assumed that the memory card 200 stores three types of digital data. In this case, three pieces of management information are stored. The management information includes first management information, second management information, and third management information. The first management information includes a data ID for specifying the first digital data managed by the first management information, a file name of the first digital data, index data representing an outline of the first digital data, A reproduction deadline and a flag of the first digital data are included. The flag is identification information indicating whether or not each digital data can be reproduced in the data reader 300. If this flag is reset, digital data cannot be reproduced.

  The secret keys stored in the ROM 112 of the data writing device 100, the RAM 314 of the data reading device 300, and the RAM 204 of the memory card 200 are set for each user who uses this system. The memory card 200 shown in FIG. 4 can be read and written only by the data writing device 100 and the data reading device 300 of this data reproduction system.

  An initial setting of the memory card 200 will be described. For mutual authentication between the memory card 200 and the data writing device 100 described later, the memory card 200 needs to be initialized. This initial setting is performed as follows.

  The user sets a memory card 200 that is not initially set in the data writing device 100. The data writing device 100 selects a user ID that can uniquely identify the user in this data reproduction system. The data writing device 100 selects one secret key stored in the ROM 112. The data writing device 100 stores the relationship between the user ID and the secret key in the RAM 114. The data writing device 100 displays the user ID and the secret key on the display unit 132. The user stores the displayed user ID and secret key. The data writing device 100 writes the secret key into the RAM 204 of the memory card 200. Digital data is written into the memory card 200 that has been initially set.

  The initial setting of the data reading device 300 will be described. The data reading device 300 needs to be initialized for mutual authentication of the memory card 200 described later. This initial setting is performed as follows.

  The user inputs the user ID and secret key stored in the data reading device 300 by the user. The data reading device 300 stores the input user ID and secret key in the RAM 314. The memory card 200 is set in the data reading device 300 having such initial settings, and digital data is read.

  Referring to FIG. 6, the program executed by data writing device 100 has the following control structure regarding the writing process.

  In step (hereinafter, step is abbreviated as S) 100, CPU 120 of data writing device 100 determines whether or not mutual authentication between data writing device 100 and memory card 200 set in data writing device 100 has been performed. Judging. The user sets the memory card 200 in the memory card interface 144. A user inputs a user ID to the operation unit 154 of the data writing device 100. The CPU 120 reads the secret key stored in the RAM 204 of the memory card 200 via the memory card interface 144. The CPU 120 matches the secret key stored in the RAM 204 of the memory card 200 with the secret key stored in the ROM 112 of the data writing device 100, and the user ID stored in the RAM 114 in relation to the matched secret key; It is determined whether or not the input user ID matches. If the private key and user ID match, it is determined that mutual authentication has been performed. If mutual authentication between data writing device 100 and memory card 200 is performed (YES in S100), the process proceeds to S102. On the other hand, if mutual authentication between data writing device 100 and memory card 200 is not performed (NO in S100), the process proceeds to S112. The case where the mutual authentication between the data writing device 100 and the memory card 200 is not performed means that when a memory card that cannot be used in this data reproduction system is used, or when a memory card that is not initialized is used, the user is not an authorized user. Such as when a person uses a regular user's memory card.

  In S <b> 102, CPU 120 displays a list of digital data stored in data writing device 100 on display unit 152 based on the index of digital data stored in nonvolatile memory 116.

  In S104, CPU 120 requests the user to select digital data. At this time, a request for selecting digital data from the displayed list is displayed on the display unit 152.

  At S106, CPU 120 reads the digital data requested at S104 from nonvolatile memory 116 and writes it into RAM 204 of memory card 200. The nonvolatile memory 116 stores digital data encrypted with a reproduction key. Encrypted digital data is written into the RAM 204 of the memory card 200.

  At S108, CPU 120 writes the current date and time detected by real-time clock 130 into the latest time of memory card 200.

  In S110, CPU 120 writes management information corresponding to the digital data written in memory card 200 in S106 to memory card 200.

  In S112, CPU 120 performs error processing when mutual authentication between data writing device 100 and memory card 200 is not performed. At this time, as error processing, the CPU 120 displays on the display unit 152 that mutual authentication is impossible.

  Referring to FIG. 7, the program executed by data reader 300 has the following control structure for the read process.

  At S200, CPU 320 of data reading device 300 determines whether or not mutual authentication between data reading device 300 and memory card 200 has been performed. The mutual authentication in S200 is performed by the data reader 300 in the above-described mutual authentication in S100. The user sets the memory card 200 in the memory card interface 344. A user inputs a user ID to the operation unit 354 of the data reading 300. The CPU 320 reads the secret key stored in the RAM 204 of the memory card 200 and the relationship between the secret key and the user ID via the memory card interface 344. The CPU 320 matches the secret key stored in the RAM 204 of the memory card 200 with the secret key stored in the RAM 314 of the data reader 300, and the user ID stored in the RAM 314 in relation to the matched secret key; It is determined whether or not the input user ID matches. If the private key and user ID match, it is determined that mutual authentication has been performed. If mutual authentication between data reader 300 and memory card 200 is performed (YES in S200), the process proceeds to S202. On the other hand, if mutual authentication between data reading device 300 and memory card 200 is not performed (NO in S200), the process proceeds to S222.

  In S202, CPU 320 displays a list of digital data stored in memory card 200 on display unit 352 using an index of digital data stored in RAM 204 of memory card 200.

  In S204, CPU 320 requests the user to select digital data to be reproduced. At this time, a request for selecting digital data from the list displayed on the display unit 352 is displayed on the display unit 352.

  In S206, CPU 320 reads the flag of the digital data selected in S204. In S208, CPU 320 determines whether or not the flag read in S206 is set. If the flag is set (YES in S208), the process proceeds to S210. On the other hand, if the flag is in the reset state (NO in S208), the process proceeds to S222.

  In S210, CPU 320 determines whether or not the current date and time detected by real-time clock 330 is later than or equal to the latest time of the memory card stored in memory card 200. If the detected current date is later than or equal to the latest time of the memory card (YES in S210), the process proceeds to S212. On the other hand, if the detected current date is earlier than the latest time of the memory card (NO in S210), the process proceeds to S222.

  In S212, CPU 320 determines whether or not the current date and time detected by real-time clock 330 is later than or equal to the latest time of the reading device stored in nonvolatile memory 316. If the detected current date and time is later than or equal to the latest time of the reading device (YES in S212), the process proceeds to S214. On the other hand, if the detected current date and time is earlier than the latest time of the reading device (NO in S212), the process proceeds to S222.

  The case where the detected current date and time is earlier than the latest time of the memory card or the latest time of the reading device is when the current date and time is advanced. This indicates that the user has illegally operated the real-time clock 330 of the data reading device 300 for the purpose of illegal reproduction after the reproduction deadline.

  In S214, CPU 320 determines whether or not the current date and time detected by real time clock 330 is earlier than or equal to the playback time limit stored in memory card 200. If the detected current date is earlier than or equal to the reproduction deadline (YES in S214), the process proceeds to S216. On the other hand, if the detected current date and time is later than the reproduction deadline (NO in S214), the process proceeds to S222.

  In S216, CPU 320 reads the digital data selected in S204 from RAM 204 of memory card 200, decrypts the digital data encrypted with the reproduction key, and outputs it from display unit 352 and audio output unit 356. The reproduction key is obtained by decrypting the reproduction key encrypted with the secret key.

  In S218, CPU 320 determines whether reproduction has ended. When the reproduction of digital data is completed (YES in S218), the process proceeds to S220. On the other hand, if the reproduction of digital data is not completed (NO in S218), the process returns to S216 to further reproduce the digital data.

  In S 220, CPU 320 overwrites the current date and time detected by real time clock 330 with the latest time of the data reading device stored in nonvolatile memory 316 and the latest time of the memory card stored in memory card 200. As a result, the latest time is updated and the reproduction ends.

  If mutual authentication is not performed in S222 (NO in S200), the flag is in a reset state (NO in S208), or if the current date and time is earlier than the latest time of the memory card (in S210) NO), if the current date and time is earlier than the latest time of the reader (NO in S212), or if the current date and time is later than the playback deadline (NO in S214), CPU 320 performs error processing. In this error processing, the CPU 320 resets the flag and erases the digital data.

  In this case, if mutual authentication is not performed, since an unauthorized user uses the memory card 200, all digital data stored in the memory card 200 is erased. When the current date and time is earlier than the latest time of the memory card and when the current date and time is earlier than the latest time of the reading device, it is determined that the real-time clock 330 of the data reading device 300 has been illegally operated. All the digital data stored in is erased. If the current date and time is later than the reproduction deadline, only the digital data for which the reproduction deadline has passed is deleted.

  The operation of the data reproduction system based on the above structure and flowchart will be described.

[Data write operation: Memory card initial setting operation]
A user of this data reproduction system sets the memory card 200 in the data writing device 100 for the initial setting of the memory card 200. When the user requests initial setting of the memory card, the data writing device 100 selects a user ID and a secret key. The selected user ID and secret key are displayed on the display unit 152. The secret key is written into the RAM 204 of the memory card 200. The relationship between the secret key and the user ID is written into the RAM 114 of the data writing device 100.

[Data write operation]
An operation of writing digital data to the memory card 200 that has been initially set will be described.

  The user connects the memory card 200 and the data writing device 100 that are initially set via the memory card interface 144 of the data writing device 100. The user inputs his / her user ID to the operation unit 152. The data writing device 100 reads the secret key from the memory card 200. The data writing device 100 and the memory card 200 are based on the read secret key and the secret key stored in the ROM 112, and on the relationship between the secret key and the user ID stored in the RAM 114 and the input user ID. Mutual authentication with is performed.

  When mutual authentication is performed (YES in S100), a list of digital data is displayed on display unit 152 based on the digital data index stored in nonvolatile memory 116 (S102). The user selects digital data to be stored in the memory card 200 from the displayed list. The selected digital data is written into the RAM 204 of the memory card 200 (S106). At this time, the digital data stored in the RAM 204 is encrypted with the reproduction key.

  The current date and time detected by the real time clock 130 is written in the latest time of the memory card (S108). Management information is created and written to the RAM 204 of the memory card 200 (S110).

  In this way, digital data is stored in the user's memory card 200 as shown in FIG.

[Data reading operation: Initial setting operation of data reader]
A user of this data reproduction system initializes the data reader 300 in order to reproduce the memory card 200 using the data reader. The user inputs a user ID and a secret key to the operation unit 354 for the initial setting of the data reader 300. The data reading device 300 stores the user ID and the secret key in the RAM 314.

[Data read operation: mutual authentication operation]
An operation of reading digital data stored in the memory card 200 using the data reader 300 that has been initialized will be described. Mutual authentication is performed before reading the digital data.

  A user connects the memory card 200 storing digital data and the data reader 300 via the memory card interface 344 of the data reader 300. The user inputs his / her user ID to the operation unit 354. The data reading device 300 reads the secret key from the memory card 200. Based on the read secret key and the secret key stored in the RAM 314, and based on the relationship between the secret key and the user ID stored in the RAM 314 and the input user ID, the data reader 300 and the memory card 200 Mutual authentication with is performed.

  When mutual authentication is performed (YES in S200), a list of digital data is displayed on display unit 352 based on the digital data index stored in RAM 204 of memory card 200 (S202). The user selects digital data to be played back stored in the memory card 200 from the displayed list. Hereinafter, the normal operation and the illegal operation will be described separately.

[Data reading operation: first normal operation]
With reference to FIG. 8, the first normal operation in data reader 300 will be described. In the following description, it is assumed that digital data is written to the memory card 200 by the data writing device 100 on January 1, 2001. It is assumed that the reproduction period of this data is until January 6, 2001. As shown in FIG. 8, January 1, 2001 is stored in the RAM 204 of the memory card 200 as the latest time of the memory card by the writing operation in the data writing device 100. In the following description, the latest time is expressed only by day, but is not limited to this, and can include hours, minutes, and seconds.

  As shown in FIG. 8, the digital data stored in the memory card can be played back from January 1, 2001 to January 6, 2001, and cannot be played back on January 7, 2001. Become. The current date and time detected by the real-time clock 330 changes sequentially from January 1, 2001 to January 7, 2001.

  A case where digital data is reproduced using the data reader 300 on January 4, 2001 before the reproduction deadline in such a state will be described. The current date (January 4, 2001) is later than the latest time of the memory card (January 1, 2001) (YES in S210), and the current date (January 4, 2001) is It is the same as the latest time (January 4, 2001) (YES in S212), and the current date (January 4, 2001) is earlier than the playback deadline (January 6, 2001) ( Digital data is read from the memory card 200 and output (S216).

  A case where digital data is reproduced using the data reader 300 on January 7, 2001 after the reproduction deadline in such a state will be described. The current date (January 7, 2001) is later than the latest time (January 1, 2001) of the memory card (YES in S210), and the current date (January 7, 2001) is Although it is the same as the latest time (January 7, 2001) (YES in S212), the current date (January 7, 2001) is later than the reproduction deadline (January 6, 2001) (in S214). NO), the digital data is not read from the memory card 200 and output.

[Data reading operation: first illegal operation]
With reference to FIG. 9, the first unauthorized operation in data reader 300 will be described. As shown in FIG. 9, it is assumed that the user of the data reading device 300 has attempted to reproduce by illegally operating the real-time clock 330 on January 7, 2001 after the reproduction deadline. It is assumed that the user has illegally changed January 7, 2001 to December 31, 2000 with respect to the current date and time detected by the real-time clock 330 of the data reader 300. Therefore, after the unauthorized operation, the current date and time of the data reader 300 is December 31, 2000.

  On January 7, 2001, the user reads the digital data stored in the memory card 200 using the illegally operated data reader 300. In this case, the current date and time (December 31, 2000: after the unauthorized operation) is earlier than the latest time (January 1, 2001) of the memory card (NO in S210), so error processing is performed. (S222). It is determined that the real-time clock 330 of the data reader 300 has been illegally operated, and all digital data stored in the memory card 300 is erased.

[Data reading operation: second normal operation]
With reference to FIG. 10, the second normal operation in data reader 300 will be described. As shown in FIG. 10, the user of the data reader 300 has two memory cards, a first memory card and a second memory card.

  Assume that digital data is written to the first memory card by the data writing device 100 on January 1, 2001. It is assumed that the reproduction period of this data is January 3, 2001. The RAM 204 of the first memory card stores January 1, 2001 as the latest time of the memory card. On the other hand, it is assumed that the second memory card stops the reproduction of digital data on January 3, 2001. The RAM 204 of the second memory card stores January 3, 2001 as the latest time of the memory card.

  In this state, a case where digital data stored in the first memory card is reproduced using the data reader 300 on January 3, 2001, which is within the reproduction period, will be described. The user sets the first memory card in the data reading device 300. The current date and time (January 3, 2001) detected by the real-time clock 330 is later than the latest time (January 1, 2001) stored in the first memory card (YES in S210). The detected current date and time (January 3, 2001) is the same as the latest time (January 3, 2001) stored in the data reader 300 (YES in S212), and the detected current date and time Since (January 3, 2001) is the same as the reproduction deadline (January 3, 2001) (YES in S214), the digital data is read from the first memory card and reproduced.

  In this state, a case where data data stored on the first memory card on January 4, 2001 after the reproduction time limit is reproduced will be described. In this case, the current date (January 4, 2001) is later than the latest time (January 1, 2001) of the memory card (YES in S210), and the detected current date (January 2001). 4th) is the same as the latest time (January 4, 2001) of the data reader 300 (YES in S212), but the detected current date (January 4, 2001) is the reproduction deadline (2001). Since January 3 of the year has passed (NO in S214), error processing is performed (S222). In this case, the flag corresponding to the corresponding digital data is reset and the digital data is erased.

[Data read operation: second illegal operation]
With reference to FIG. 11, the second illegal operation in data reader 300 will be described. As shown in FIG. 11, it is assumed that the user of the data reading device 300 has attempted to reproduce by illegally operating the real-time clock 330 on January 4, 2001 after the reproduction deadline. It is assumed that the user has illegally changed January 4, 2001 to January 2, 2001 with respect to the current date and time detected by the real-time clock 330 of the data reader 300. Therefore, after the unauthorized operation, the current date and time of the data reader 300 is January 2, 2001.

  On January 4, 2001, the user reads the digital data stored in the memory card 200 using the data reader 300 that has been illegally operated. In this case, the current date and time (January 2, 2001: after the unauthorized operation) is later than the latest time of the memory card (January 1, 2001) (YES in S210), but the current date and time (2001) Since January 2 (after the unauthorized operation) is before the latest time of the reading device (January 3, 2001) (NO in S212), error processing is performed (S222). In this case, it is determined that the real-time clock 330 of the data reading device 300 has been illegally operated, and all digital data stored in the memory card 200 is erased.

  As described above, according to the data reproduction system of the present embodiment, the current date and time detected by the data writing device is written to the memory card when the data writing device writes data. The current date and time detected by the data reader is stored in the storage unit of the data reader. At the time of data reproduction, based on the latest time of the memory card stored in the memory card, the latest time of the reader stored in the storage unit of the reader, and the current date and time detected by the real-time clock of the reader An illegal operation of the current date and time in the reader is detected. When the current date and time of the data reading device are not manipulated illegally and within the reproduction time limit, the digital data stored in the memory card is reproduced. As a result, a data reproduction system that outputs data via the reproduction time limit can be realized at low cost.

<First Embodiment First Modification>
A first modification of the above-described first embodiment will be described.

  As shown in FIG. 12, in this modification, in the data reading device 300, the latest time stored in the memory card 200 set in the data reading device 300 is overwritten with the current date and time detected by the data reading device 300. Is.

  As shown in FIG. 12, the latest time stored in the memory card 200 is overwritten with the current date and time detected by the real time clock 330 of the data reader 300 at predetermined time intervals. Therefore, the latest time of the memory card 200 stored in the memory card is changed with the passage of time.

  Assume that digital data is written to the memory card 200 on January 1, 2001 using the data writing device 100. The reproduction period of this data is assumed to be January 6, 2001.

  In such a state, it is assumed that the user of the data reading device 300 has attempted the reproduction by illegally operating the real-time clock 330 on January 7, 2001 after the reproduction deadline. It is assumed that the user illegally changed January 7, 2001 to January 6, 2001 with respect to the current date and time detected by the real-time clock 330 of the data reader 300. Therefore, after the unauthorized operation, the current date and time of the data reader 300 is January 6, 2001.

  On January 7, 2001, the user reads the digital data stored in the memory card 200 using the illegally operated data reader 300. In this case, since the current date and time (January 6, 2001: after the unauthorized operation) is later than the latest time of the memory card (January 6, 2001) (NO in S210), error processing is performed (S222). ). It is determined that the real-time clock 330 of the data reader 300 has been illegally operated, and all digital data stored in the memory card 300 is erased.

<First Embodiment Second Modification>
A second modification of the above-described first embodiment will be described. Referring to FIG. 13, the second modification stores the latest time of the memory card regardless of the current date and time detected by the real time clock 330 of the data reader 300. The data reader 300 in the second modified example includes a counter that can calculate the elapsed time in addition to the real-time clock 330. As shown in FIG. 13, when the reproduction of digital data stored in the memory card 200 is started on January 1, 2001, the elapsed time from the start of reproduction is detected by a counter. The current date and time are calculated by adding the elapsed time detected by the counter to the current date and time detected when playback is started. Thus, even when the real-time clock 330 is not tampered with at the start of playback and is tampered with after the start of playback (for example, when the real-time clock 330 is tampered with on January 4, 2001), the memory card In 200, the latest time of the memory card is accurately stored.

  In the data reader 300 using the second modified example, the operation when the real-time clock 330 is illegally operated on January 7 is the same as the first modified example described above. The explanation will not be repeated.

  Also in the modified example described above, the same effects as those of the first embodiment described above can be obtained, and a data reproduction system that reproduces digital data by managing the reproduction time limit can be realized at low cost.

<Second Embodiment>
Hereinafter, an embodiment in which the memory card in the first embodiment described above is used as another recording medium will be described. Except for the change in the structure of the recording medium, the configuration is the same as that of the first embodiment, and detailed description thereof will not be repeated here.

  Referring to FIG. 14, a recording medium 210 replacing memory card 200 includes a memory card interface 212 and a storage unit 214 connected to memory card interface 212 and realized by a magneto-optical disk. As shown in FIG. 14, since the storage unit 214 is realized by a magneto-optical disk, large-capacity digital data (digital data representing high-quality video) and the like can be stored.

  Referring to FIG. 15, a recording medium 220 replacing memory card 200 includes a memory card interface 222, a first storage unit 224 that stores data that needs to be rewritten, and a second storage that stores data that does not need to be rewritten. Storage unit 226. The first storage unit 224 and the second storage unit 226 are connected to the memory card interface 222. The first storage unit 224 stores the latest time and secret key of the memory card, and the second storage unit 226 stores digital data that does not need to be rewritten.

  This eliminates the need for the data writing device 100 shown in FIG. A user purchases a recording medium 220 in which digital data is stored in advance in the second storage unit 226, sets the recording medium 220 in the data reader 300, and reproduces the digital data stored in the second storage unit 226. Can do.

  Referring to FIG. 16, a recording medium 230 includes a second storage unit 236 in which the second storage unit 226 of the recording medium 220 shown in FIG. 15 is realized by a magneto-optical disk. In addition to the effects of the recording medium 220 shown in FIG. 15, the recording medium 230 shown in FIG. 16 can store a large amount of digital data in the second storage unit 236.

  Referring to FIG. 17, the recording medium 240 includes a second storage unit 246 in which the second storage unit 236 of the recording medium 230 shown in FIG. 16 is realized by a read-only optical disc.

  Referring to FIG. 18, instead of the memory card 200 of the first embodiment, a recording medium 250 uses a memory card interface 252 and a one-time writable optical disk connected to the memory card interface 252. Storage unit 254 included. In the storage unit 254, digital data that does not require rewriting is encrypted and stored, and management information is additionally written.

  With reference to FIG. 19, data stored in the storage unit 254 of the recording medium 250 shown in FIG. 18 will be described. As shown in FIG. 19, first, the first digital data encrypted with the reproduction key and the second digital data encrypted with the reproduction key are written in the storage unit 254. As initial management information, a secret key, a reproduction key encrypted with the secret key, and an initial latest time are stored. As initial management information, management information about the written first digital data and second digital data is stored. The first management information includes a data ID, a file name, index data, a reproduction time limit, and a flag.

  As illustrated in FIG. 19, the storage unit 254 includes additional storage information of digital data. The additional management information includes management information of digital data additionally stored in addition to the first digital data and the second digital data. This management information is additionally written and stored.

  As shown in FIGS. 18 and 19, the storage unit 254 is configured by using an optical disk that can be written only once, appropriately stores digital data, and additionally writes management information corresponding to the additionally stored digital data. The recording medium 250 in which digital data is stored can be realized.

  As described above, even when the recording medium according to the second embodiment is used, the same effects as those of the first embodiment can be realized.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure showing the whole data reproduction system composition concerning an embodiment of the invention. FIG. 2 is a control block diagram of the data writing device shown in FIG. 1. FIG. 3 is a control block diagram of the data reader shown in FIG. 2. FIG. 2 is a control block diagram of the memory card shown in FIG. 1. It is a figure showing the data memorize | stored in the memory card shown in FIG. It is a flowchart which shows the write-in process which concerns on embodiment of this invention. It is a flowchart which shows the data reading process which concerns on embodiment of this invention. It is a figure which shows the 1st normal operation | movement in embodiment of this invention. It is a figure which shows the 1st unauthorized operation | movement in embodiment of this invention. It is a figure which shows the 2nd normal operation in embodiment of this invention. It is a figure which shows the 2nd unauthorized operation | movement in embodiment of this invention. It is a figure which shows the unauthorized operation | movement in the 1st modification of embodiment of this invention. It is a figure which shows the unauthorized operation | movement in the 2nd modification of embodiment of this invention. FIG. 3 is a control block diagram (part 1) of the recording medium. FIG. 6 is a control block diagram (part 2) of the recording medium. FIG. 6 is a control block diagram (part 3) of the recording medium. FIG. 6 is a control block diagram (part 4) of the recording medium. FIG. 10 is a control block diagram (part 5) of the recording medium. It is a figure showing the data memorize | stored in the recording medium shown in FIG.

Explanation of symbols

  100 data writing device, 200 memory card, 300 data reading device, 400 data distribution server, 500 network, 110, 310 storage unit, 120, 320 CPU, 130, 330 real time clock, 140 interface unit, 150, 350 I / O unit.

Claims (17)

A data reproduction system for reading data written on a recording medium by a data writing device by a data reading device,
The data writer is
Storage means for storing data;
Detection means for detecting date and time;
Connected to the storage means and the detection means, the data to the recording medium, a time limit for outputting the data by the data reader, the data to the recording medium detected by the detection means, and Writing means for writing the writing date and time of the deadline,
The data reader is
Detection means for detecting the current date and time;
Reading means for reading the time limit and the writing date and time from the recording medium;
Connected to the detection means and the reading means of the data reader, and determines whether the data written to the recording medium can be output based on the time limit, the writing date and time, and the current date and time. Judgment means for,
Output means for reading and outputting the data from the recording medium when the data is output when connected to the reading means and the determining means;
The determination unit is configured to determine that the output of the data written to the recording medium is impossible if the current date and time is earlier than the write date and time even before the time limit. A data reproduction system including means.   The data reader further includes an overwrite unit connected to a detection unit of the data reader and overwriting the current date and time with a write date and time written on the recording medium at the end of data reproduction. Item 4. The data reproduction system according to Item 1.   The data reading device further includes an overwriting unit connected to the detecting unit of the data reading device and overwriting the current date and time with a writing date and time written in the recording medium at regular intervals during data reproduction. The data reproduction system according to claim 1.   The determining means includes means for determining that the data written to the recording medium can be output when the current date and time is after the writing date and time and before the deadline. The data reproduction system according to any one of claims 1 to 3. The detection means of the data reader comprises
Means for detecting the date and time of output start of the data;
Means for detecting an elapsed time from the output start date and time;
The data reproduction system according to claim 1, further comprising means for detecting a current date and time based on the date and time of the output start and the elapsed time.   2. The data reproduction according to claim 1, wherein the data reading device further includes erroneous date detection means for detecting that the current date is incorrect when the current date is earlier than the writing date. system.   The data reading device further includes processing means connected to the erroneous date and time detection means and for making it impossible to read the data from the recording medium when it is detected that the current date and time is incorrect. The data reproduction system according to claim 6. A data writing device used in a data reproduction system for reading data written on a recording medium by a data writing device by a data reading device,
Storage means for storing data;
Detection means for detecting date and time;
Connected to the storage means and the detection means, the data to the recording medium, a time limit for outputting the data by the data reader, the data to the recording medium detected by the detection means, and A data writing device including writing means for writing the date and time of writing of the deadline. A data reader used in a data reproduction system for reading data written on a recording medium by a data writer by a data reader,
Detection means for detecting the current date and time;
Reading means for reading from the recording medium a time limit and a writing date and time at which the data reading device can output the data;
Judgment means connected to the detection means and the reading means for judging whether or not the data written to the recording medium can be output based on the time limit, the writing date and time, and the current date and time. When,
Output means for reading and outputting the data from the recording medium when the data is output when connected to the reading means and the determining means;
The determination unit is configured to determine that the output of the data written to the recording medium is impossible if the current date and time is earlier than the write date and time even before the time limit. A data reader comprising means.   10. The data reading device according to claim 9, further comprising an overwriting unit connected to the detecting unit and overwriting the current date and time on a writing date and time written on the recording medium at the time of completion of data reproduction. Data reader.   The data reading device further includes an overwriting unit connected to the detecting unit and overwriting the current date and time on a writing date and time written on the recording medium at regular intervals during data reproduction. The data reading device described in 1.   The determining means includes means for determining that the data written to the recording medium can be output when the current date and time is after the writing date and time and before the deadline. The data reader according to any one of claims 9 to 11. The detection means includes
Means for detecting the date and time of output start of the data;
Means for detecting an elapsed time from the output start date and time;
The data reading device according to claim 9, further comprising means for detecting a current date and time based on the date and time of the output start and the elapsed time.   The data reading device according to claim 9, wherein the data reading device further includes erroneous date detection means for detecting that the current date is incorrect if the current date is earlier than the writing date. apparatus.   The data reading device further includes processing means connected to the erroneous date and time detection means, and making it impossible to read the data from the recording medium when it is detected that the current date and time are incorrect. The data reading device according to claim 14. A data writing method in a data writing device used in a data reproduction system for reading data written on a recording medium by a data writing device by a data reading device, wherein the data reading device reads the time limit read from the recording medium And the writing date and time and the detected current date and time, it is determined whether or not the data written to the recording medium can be output, and if the data can be output, the data is read from the recording medium. Read and output,
The data writing method is:
Preparatory steps to prepare the data;
A detection step for detecting the date and time;
A data writing method, comprising: a writing step of writing the data, a time limit for outputting the data by the data reader, and a writing date and time of the time limit to the recording medium on the recording medium. A data reading method in a data reading device used in a data reproduction system for reading data written on a recording medium by a data writing device by a data reading device, wherein the data writing device uses the data reading device to read the data Set the time limit that can be output, and write the data, the time limit, the data to the recording medium and the date and time of writing the time limit to the recording medium,
The data reading method includes:
A detection step for detecting the current date and time;
A reading step of reading the time limit and the writing date and time from the recording medium;
A determination step of determining whether the data written to the recording medium can be output based on the time limit, the writing date and time, and the current date and time;
An output step of reading and outputting the data from the recording medium when the output of the data is possible,
The determination step includes a step of determining that the output of the data written on the recording medium is impossible if the current date is earlier than the write date even if the current date is earlier than the deadline. Including data reading method.

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