Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Patent
1990-08-13
1992-08-25
Envall, Jr., Roy N.
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
3692753, 235454, 235494, G11B 700, G11B 724
Patent
active
051425190
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to an optical recording medium having a plurality of guide lines and data regions which are defined between adjacent guide lines and usable for optically recording data therein.
2. Background Art
Hitherto, an optical recording medium of this kind has linear track guides and data regions.
Reading and writing of data are accomplished by a self-clock method in which synchronization is achieved by means of clock bits contained in the data, while tracking is conducted to follow up a track guide.
The conventional optical recording medium, however, suffers from the following problems due to the use of the self-lock method. Namely, once the lock of the tracking is broken due to, for example, a contaminant or flaw in the surface of the optical recording medium, reading of data fails until the next clock bit is read. In addition, erroneous reading of data tends to result after a relocking, due to the fact that there is no means for identifying the leading end of the data.
SUMMARY OF THE INVENTION
In order to overcome the above-described problems of the know art, according to the present invention, there is provided an optical recording medium having a plurality of guide lines and data regions which are defined between adjacent guide lines and in which data is optically recorded, wherein each guide line includes a start guide indicating the leading end of the data region, clock guides arranged at a predetermined interval to follow the start guide and enabling synchronization during reading and writing, and sector marks arranged at a predetermined interval so as to divide the data region into a plurality of sectors, the clock guides on adjacent guide lines being arranged in such a staggered manner that the clock guides appear alternately in both guide lines, the data region having sector number writing portions provided in the vicinity of each sector mark for writing a sector identification number to be written therein.
According to the invention, since clock guides are provided on guide lines such that clock guides on two adjacent guide lines appear alternately, it is possible to easily recognize that the head has been moved to the next data bit during reading or to the next data bit writing position during writing.
According to the invention, each track as the data region is sectioned into a plurality of sectors at a constant interval, and sector marks indicating the border between the adjacent sectors are provided on the guide line. Thus, each track is divided into a plurality of sectors. In the known recording mediums, one full track becomes unusable when a flaw or a contaminant resides on the track. In contrast, according to the invention, only the sector of a track which has a contaminant or a flaw becomes unusable, and other sectors of the same track still remain usable, whereby the efficiency of the recording region is improved.
In addition, since identification number of each sector is written in the data regions subsequent to the guide line, it becomes possible to definitely recognize and identify the sector. It is therefore possible to promptly recognize the position of the sector when the tracking is locked again after accidental unlocking due to presence of a flaw or contaminant on the surface of the optical recording medium.
In a preferred form of the present invention, the sector mark has a length which is n times as large the length of the clock guide, where n is an integer. This eliminates the necessity for synchronization because there is no offset of the timing between the binarized signal of the clock guide and the output signal from the PLL circuit.
According to another aspect of the present invention, there is provided an apparatus for reading and writing data from and in the optical recording medium, comprising: a clock guide reading section for reading the guide line and attaining synchronism by using the read clock guides; data reading section for reading data using, as references, the synchronizing signals derive
REFERENCES:
patent: 4787075 (1988-11-01), Matsuoka et al.
patent: 4982075 (1991-01-01), Aoki et al.
patent: 4982391 (1991-01-01), Sakagami et al.
patent: 4985616 (1991-01-01), Nakamura et al.
patent: 4998009 (1991-03-01), Iijima et al.
Envall Jr. Roy N.
Kabushiki Kaisha CSK
Tran Thang V.
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