Digital disk recording and reproduction apparatus

Details Digital disk recording and reproduction apparatus Digital disk recording and reproduction apparatus

2000-06-23

2001-11-27

Huber, Paul W. (Department: 2651)

Dynamic information storage or retrieval

Control of storage or retrieval operation by a control...

Control of information signal processing channel

C369S124140

Reexamination Certificate

active

06324138

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a digital recording method, a digital disk, a digital disk recording apparatus, and a digital disk reproduction apparatus, and more particularly, to a digital recording method for recording digital data efficiently onto a medium, a digital disk, a digital disk recording apparatus, and a digital disk reproduction apparatus.
BACKGROUND ART
The media of magneto-optical disks, optical disks, phase change disks, and the like are known as digital disks. The recording and reproduction of the disk are all carried out by data transfer in AC coupling. This means that it is difficult to record/reproduce signal components of the low frequency region at high efficiency with respect to data recorded at high density on a digital disk.
It is therefore necessary to carry out modulation that suppresses the direct current and low frequency components for recording data. The recorded data stream includes the clock frequency components of recording. At the time of reproduction, the clock frequency components are extracted from the signal of the reproduced data stream. Self clock control is provided that reproduces the reference clock of the reproduction apparatus by the extracted clock frequency component. In modulating digital data, self clock control must be feasible and with few direct current and low frequency components. EFM,
1
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7
RLL modulation,
2
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7
RLL modulation and the like are known as such modulation systems. RLL-modulated data is NRZI-modulated or NRZ-modulated and recorded on a medium.
Japanese Patent Laying-Open No. 2-96982 proposes a method of preparing a plurality of pseudo random data streams and scrambling the data stream with the pseudo random data that has the smallest DSV (Digital Sum Variation) at the time of recording. Such an adaptive type modulation method that reduces the value of DSV is proposed.
It is known to form a sine wave shape (wobble shape) having a predetermined cycle and amplitude at the wall of a groove in a disk medium. This wobble is well known by those skilled in the art as disclosed in, for example, Japanese Patent Laying-Open No. 7-311962. Address information and the like are recorded in a multiplexed manner by this wobble.
SUMMARY OF THE INVENTION
A main object of the present invention is to provide a digital recording method of favorable digital recording efficiency, a digital disk, a digital disk recording apparatus and a digital disk reproduction apparatus.
Another object of the present invention is to propose an example of an adaptive type modulation method that suppresses direct current and low frequency components.
The present invention is directed to a digital recording method of selecting and recording modulation record data that has the direct current component at the time of recording suppressed, out from a group of modulation record data candidates. A plurality of types of data of a predetermined number of bits are added to input data as initial data. In a predetermined sequence for every predetermined number of bits, exclusive-OR is taken between the current code modulation unit to be transformed and the code modulation unit immediately preceding that current code modulation unit. By applying a convolution process substituting for that current code modulation unit, a group of candidates of a plurality of types of modulation record data are generated from the input data. The direct current component in the recording operation of each of the plurality of modulation record data are compared with each other. Modulation record data is selected and recorded according to the comparison result. By the invention of the present application, the direct current component at the recording/reproduction system can be suppressed with only a slight increase in data length.
According to a preferable embodiment of the present invention, the data length n of the initial data added to the input data is 2≦n≦32. More preferably, the data length n of the initial data is 4≦n≦8.
Further preferably, the data length m of the input data is L times (L is an integer of at least 2) the initial data.
According to another aspect of the present invention, a digital disk has a wobble formed. A data stream is formed in phase synchronization with the wobble configuration.
According to another aspect of the present invention, a digital disk recording apparatus writes data in synchronization with the wobble formed in a digital disk. A wobble signal is extracted from the digital disk. A reference clock signal is generated in synchronization with the wobble signal. Data is written according to the reference clock signal.
According to yet another aspect of the present invention, a digital disk reproduction apparatus reads out written data in synchronization with the wobble formed in a digital disk. A wobble signal is extracted from the digital disk. A reference clock signal is generated in synchronization with this wobble signal. A reproduced signal is digitized by the reference clock signal.


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Hirotake Ishii et al: “A New 8-12 Conversion Channel Code And Its Application to High Data-Rate Video Recording” Electronics & Communications in Japan, vol. 78, No. 7, Jul. 1, 1995 (Aug. 1, 1995), pp. 103-113, XP000545773, ISSN: 8756-663X (the whole document).

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