Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
2001-09-05
2002-12-24
Kim, Hong (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S154000, C711S163000, C711S170000, C235S380000
Reexamination Certificate
active
06499084
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a digital recording and reproducing apparatus which is capable of recording and reproducing recorded data by using a removable external memory as a recording medium.
2. Description of the Related Art
As a digital recording and reproducing apparatus of the above-mentioned kind, a sound recording and reproducing apparatus is known which uses a card-type removable memory (hereinafter referred to as the “memory card”) as a recording medium. In this sound recording and reproducing apparatus, an analog sound signal input via a microphone is subjected to analog-to-digital conversion to generate sound data, and the sound data is recorded in the memory card. In this case, in a sound recording and reproducing apparatus of this kind, generally, when production of sound data in a memory card has been completed, FAT (File Allocation Table) data of the sound data is recorded in a FAT data recording area of the memory card. On the other hand, when a sound is to be reproduced, sound data thereof is read out from the memory card in accordance with the FAT data, and then digital-to-analog conversion of the sound data is carried out to thereby generate an analog sound signal. This analog sound signal is sounded from a speaker or an earphone.
The above sound recording and reproducing apparatus, however, suffers from the following problems: In the sound recording and reproducing apparatus, a general-purpose memory card is employed as a recording medium for recording sound data. In this case, the memory card is configured such that it can be removed from the sound recording and reproducing apparatus and used in another sound recording and reproducing apparatus or a personal computer, and moreover such that it can reproduce a sound based on sound data and edit the sound data by using the apparatus or the personal computer. This makes it possible to dishonestly rewrite sound data recorded in the memory card. On the other hand, differently from analog sound data recorded by an analog recording and reproducing apparatus, digital sound data recorded by the digital recording and reproducing apparatus makes it difficult, for instance, even if part of the sound data was overwritten, to clearly recognize a boundary between original sound data originally recorded in the memory card and the overwritten sound data. Therefore, it is difficult for the conventional sound recording and reproducing apparatus to determine whether or not the present sound data is overwritten, and further whether or not the sound data is authentic.
In the above case, if part of sound data was overwritten in a quite normal fashion, FAT (File Allocation Table) data of the sound data is replaced by FAT data of new sound data, so that there is generated FAT data which is different from an original FAT data in date information and recording address information. Therefore, when sound data was recorded in the memory card, if FAT data of the sound data is caused to be stored in a built-in memory, and it is determined, when a sound is reproduced based on the sound data, whether or not FAT data items stored in the memory card and the built-in memory respectively are identical to each other, it is possible to determine whether or not the sound data was rewritten. However, since FAT data itself can be rewritten relatively easily, it is possible, for instance, to rewrite the sound data dishonestly to restore FAT data having the same contents with those of FAT data corresponding to the original sound data. This makes it difficult, when the FAT data was restored, to determine whether or not the sound data was rewritten in spite of the fact that the sound data was rewritten.
Further, to prevent sound data from being rewritten by a third party, there have been already devised a technique which records a predetermined user identification code in a memory card in advance such that only a sound recording and reproducing apparatus which first recorded sound data in the memory card can rewrite the sound data, and a technique which encrypts sound data per se to thereby disable rewriting of the sound data by another sound recording and reproducing apparatus. According to the former technique, rewriting of recording data can be prevented. However, it is required to record beforehand user identification codes different from each other in a manner associated with a corresponding one of a very large number of memory cards since it is necessitated to record a user identification code in each memory card in advance. Consequently, the user identification codes themselves become complicated and large-sized codes. Therefore, an important data recordable area of the memory card is occupied by the large-sized codes. Further, it takes a long time period to carry out identification processing for identification of a complicated and large-sized user identification code, and at the same time necessitates a sophisticated identification program and a high performance control section, which results in increased manufacturing costs of the sound recording and reproducing apparatus. On the other hand, the latter technique which encrypts sound data per se suffers from the problem that it takes a longer time period to carry out recording processing for recording sound data due to intricate encryption processing, and moreover it takes a longer time period to carry out reproduction processing for reproducing sound data due to decoding processing for decoding the encrypted sound data. Additionally, a sophisticated processing program for encrypting and decoding sound data and a high performance control section are necessitated.
SUMMARY OF THE INVENTION
It is a main object of the invention to provide a digital recording and reproducing apparatus which is capable of determining whether or not recording data was rewritten, reliably and in a short time period without increasing manufacturing costs thereof.
To attain the above object, the invention provides a digital recording and reproducing apparatus which is capable of having a removable external memory mounted therein, for performing recording of recording data in the external memory and reproduction based on the recording data recorded in the external memory, the digital recording and reproducing apparatus comprising an identification data-generating block for generating identification data for use in determining whether or not the recording data was rewritten, an internal memory in which the identification data can be recorded, and a control block for recording the identification data in the external memory as part of the recording data and at the same time recording the identification data in the internal memory in a manner correlated to a title of a file to be recorded in FAT data concerning the recording data, wherein when the control block reads in the recording data from the external memory, if the identification data corresponding to the title of the file in the FAT data concerning the recording data read in from the external memory exists in the internal memory, the control block compares the existing identification data and the identification data recorded in the recording data read in with each other, and carries out predetermined processing if the compared identification data are different from each other.
The digital recording and reproducing apparatus according to the invention includes the identification data-generating block for generating identification data, the internal memory in which the identification data can be recorded, and the control block for recording the identification data recorded in the external memory in the internal memory in a manner correlated to the title of the file of the recording data, and when the identification data corresponding to the title of the file of the recording data exists in the internal memory, the control block compares the two identification data recorded in the external memory and the internal memory, respectively, and carries out predetermined processing if the identification data are different fr
Fujii Ken
Kobayashi Nobuyuki
Kim Hong
TDK Corporation
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