Dynamic information storage or retrieval – Systems having plural physically distinct independent tracks... – Having layered storage medium
Reexamination Certificate
1996-01-05
2001-07-31
Hindi, Nabil (Department: 2516)
Dynamic information storage or retrieval
Systems having plural physically distinct independent tracks...
Having layered storage medium
C369S059160, C369S053130, C369S275300
Reexamination Certificate
active
06269065
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Utilization
This invention relates generally to a recording medium for recording audio data in a new data format and, more specifically, to a two-layered recording medium.
2. Description of the Background
Compact disks (CD's) are now very popular as a recording media with high audio quality and typically have a diameter of about 12 cm on which digital audio data is recorded having a sampling frequency fs equal to 44.1 kHz and with 16-bit quantization.
With the progress in the audio industry and the requirement for a higher capacity and a higher transfer rate of various recording media, higher sound quality is required for the CD, which is referred to hereinafter as the first generation CD, and for realizing such higher sound quality the first approach to be considered is increasing the sampling frequency.
More specifically, the sampling frequency fs=44.1 kHz of the first generation CD restricts the frequency band component of the audio signal data up to 20 kHz, and the higher sampling frequency allows the CD to record audio data of frequencies higher than 20 kHz and a more natural fidelity sound is recorded and reproduced.
It is possible to construct a new CD media system having a data format with a higher sampling frequency than that of the first generation CD, however, such new CD media system involves various practical problems. If such new CD media system is realized, it is inevitably required that it be compatible with the first generation CD. For example, a playback device structured for new CD having a data format with the high sampling frequency is required also to playback the first generation CD. On the other, from the view point of the CD system as a recording medium, it is required that the new CD should be able to be played back on the conventional player used for the first generation CD.
Thus, although the high sound quality could be realized by simply increasing the sampling frequency, the new CD cannot be reproduced using a player for the first generation CD, so that such a new CD is not sufficient as a new CD system.
A player for the new CD system can be constructed to play back the first generation CD, however, to perform such playback, two series of digital playback circuits performing the functions of a decoder and a D/A converter for the first generation CD and a decoder and a D/A converter for the new CD system are necessary. Of course, a clock generator is also required for each circuit. Such added circuitry results in a complex, large sized, and expensive circuit structure of the playback device. Therefore, it is not a suitable solution to the problem of improving CD sound quality.
OBJECTS AND SUMMARY OF THE INVENTION
In view of solving the above-mentioned problem, it is an object of the present invention to provide a new recording medium is playable on a playback device for the first generation recording medium and also to provide a recording/reproducing apparatus for this new recording medium.
According to one aspect of the present invention, to achieve this object the recording layer is structured to have a plurality of layers comprising at least a first layer and a second layer, wherein on the first layer an audio data program recorded in the first data format, and on the second layer the audio data program recorded in the second data format. The audio data program recorded on the first layer and the second layer is the same program.
More specifically, the data recorded, for example, on the first layer which is readable on a playback device for the first generation recording medium is provided with a data format of the first generation recording medium for playback on a conventional playback device, on the other hand, when the recording medium is used on a playback device for the new system, the data recorded on the second layer on which data of a high sound quality format is recorded is read out to play back high-quality sound. As described hereinbelow, the present invention provides a high sound quality media as a new recording medium system, and also the present invention provides the convenience of compatibility with conventional playback devices.
Particularly, the second data format is provided with a sampling frequency that is an integral multiple of the sampling frequency of the first data format, the integral multiple relationship allows the structure of the compatible device for playing back the first generation recording medium and the recording medium of the present invention to be very simple.
The second data format is prescribed to the one-bit &Dgr;&Sgr; modulated signal, whereby it is possible to increase remarkably the sampling frequency and sufficiently high sound quality is realized.
More specifically, data recorded on the layer that is readable by a playback player for the first generation recording medium, that is, the first layer, is rendered in the data format for the first generation recording medium and the data is regenerated or reproduced using a conventional playback device, and a playback device for the new system reads data on the second layer on which high sound quality format data are recorded, thus, high sound quality playback is realized. A sampling frequency that is an integral multiple of that of the first data format is assigned to the second data format, so that the possibly complex structure of the compatible device for playback of both the first generation recording medium and the new recording medium of the present invention is avoided.
Moreover, it is easy to increase greatly the sampling frequency by applying a one-bit &Dgr;&Sgr; modulated signal.
REFERENCES:
patent: 5175720 (1992-12-01), Clark
patent: 5381401 (1995-01-01), Best et al.
Nishio Ayataka
Ogura Yasuhiro
Hindi Nabil
Maioli Jay H.
Sony Corporation
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