Pulse or digital communications – Spread spectrum – Direct sequence
Reexamination Certificate
1998-06-16
2002-04-30
Pham, Chi (Department: 2631)
Pulse or digital communications
Spread spectrum
Direct sequence
C375S141000, C713S152000, C370S527000, C348S469000, C386S349000
Reexamination Certificate
active
06381262
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information signal processing unit for detecting additional information from an information signal to which the additional information is added and processing it.
2. Description of the Related Art
Recently, a reproducing unit for a digital video tape recorder (VTR) and a digital video disc (DVD) and software reproducible using these units are provided in numbers, digitized video signal and aural signal can also be reproduced readily at home, and an image and a sound/voice respectively excellent in the quality of an image and a sound/voice can be reproduced.
Digitized video signal and aural signal or a program are plentifully provided via a recording medium such as the Internet and a compact disc read only memory (CD-ROM) and digitized software provided via the Internet, CD-ROM and others is widely utilized using a personal computer and others.
However, in the meantime, there is a problem that software plentifully provided as described above and composed of digitized video signals and others may be unlimitedly copied. Therefore, if digitized information, for example a video signal is dealt with, direct copy preventing control such as copy prohibition is executed by adding a copy preventing code to a digital video signal as digital data and recording it on a recording medium.
Not only a copy preventing code for prohibiting or allowing copy is added but a code for limiting the generation of copy is added to a digital video signal and more flexible control over copy is also executed.
FIG. 1
is a basic block diagram showing a copy system in case digitized information is dealt and the copy system is provided with functions for sending digital information read by a digital information reading device
110
to a digital information recording device
120
, copying information which can be copied, prohibiting the copy of information the copy of which is not allowed and updating the following digital information in case a code for limiting the generation of copy exists in digital information.
Copy control information as additional information is recorded in addition to digital main information in a recording medium
111
installed in the digital information reading device
110
. The copy control information is provided with the prohibition or allowance of copy, the limitation of a generation and others as control contents.
The reading section
112
of the digital information reading device
110
generates a digital read information signal D
2
composed of digital main information and copy control information added to the digital main information based upon a signal D
1
obtained by reading information in the recording medium
111
and sends the above signal to the digital information recording device
120
.
The additional information reading section
121
of the digital information recording device
120
detects copy control information CC from the received digital read information signal D
2
and sends the detected copy control information CC and the digital read information signal D
2
to an additional information changing section
122
.
The additional information changing section
122
generates new additional information based upon copy control information CC in case copy control information added to a digital information signal D
2
is required to be changed and changes copy control information added to the digital information signal D
2
by adding the new additional information to the digital information signal D
2
.
For example, if copy control information CC is generation limited information of which the copy of only a first generation is allowed, the additional information changing section
122
changes copy control information by generating new copy control information the control contents of which represent the prohibition of copy and adding this new copy control information to the digital information signal D
2
.
As a result, as described above, a digital information signal D
3
to which copy control information changed if necessary is added and copy control information CC are output from the additional information changing section
122
and sent to a writing section
123
.
The writing section
123
converts the above digital read information signal D
3
to digital information suitable for recording if copy control information CC supplied via the additional information changing section
122
represents the allowance of recording a digital read information signal from the digital information reading device
110
and writes the above converted digital information to a recording medium
124
. In the meantime, if copy control information CC from the additional information reading section
121
represents the prohibition of copy, the wiring section
123
does not record the above digital read information signal D
3
.
Further, if copy control information CC from the additional information reading section
121
represents that the copy of only a first generation is allowed, the digital read information signal D
3
to which new copy control information is added by the additional information changing section
122
as described above is converted to digital information suitable for recording and is written to the recording medium
124
. In this case, a digital information signal cannot be copied using a copied recording medium
124
.
As described above, in the case of so-called digital connection that a main information signal and copy control information as additional information are supplied to the recording device as a digital signal, the recording device can securely execute copy preventing control such as the prohibition of copy using copy control information because copy control information is included in transmitted digital data.
As described above, even if information recorded in a recording medium in which a digital video signal as a main information signal and copy control information as additional information are recorded is read using a digital reading device and copy control information is obtained together with a digital video signal, only a digital video signal which is a main information signal can be converted to an analog signal via a D/A converting circuit to monitor an image for example and can be output to an analog output terminal to which a picture tube of a monitor is normally connected.
As described above, even if digital information is read by a reading device, a copy control signal is not included in an analog signal output to the analog output terminal. Therefore, in the case of analog connection in which analog VTR and others are connected to an analog output terminal, control over copy based upon copy control information is disabled, for example the copy of a main information signal the copy of which is prohibited is enabled and the limitation of a generation of copy is also disabled.
As copy control information is often added in a header and others separately from a digital video signal as a main information signal even in the case of digital connection, copy control based upon copy control information is disabled and illegal copy is enabled by deleting information in a part to which copy control information is added and falsifying copy control information such as replacing with another information.
Further, it is also conceivable that when copy control information is superimposed or added in a frequency band different from the frequency band of these video signal and aural signal even if a video signal and an aural signal respectively as a main information signal are an analog signal or a digital signal, copy control information is deleted by a simple frequency filter and copy control based upon copy control information is disabled.
Therefore, as described above referring to
FIG. 1
, as the signal strength of additional information such as copy control information added to a main information signal is weak and additional information cannot be regenerated in case it is once deleted even if more flexible copy control is executed by providing a function for changing
Maioli Jay H.
Pham Chi
Phu Phuong
Sony Corporation
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