Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
1998-11-24
2001-04-17
Edun, Muhammad (Department: 2651)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S059160, C369S053130, C369S047360
Reexamination Certificate
active
06219319
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus capable of writing digital data or data such as digital image, audio, system, etc. into an optical disk (including optical magnetic disk, and phase change disk) medium and reading the data therefrom wherein a side of an inner radius of the disk is efficiently utilized, and the number of revolutions in the disk is reduced as much as possible for elevating capacity for writing, whereby high density writing, non-linear editing, high-speed search and the like are realized at the same time.
BACKGROUND OF THE INVENTION
In a disk (optical disk, optical magnetic disk, phase change disk) unit into which digital data or image-audio data is written, a CAV or CLV system, and a combined system thereof, have been proposed heretofore.
CAV system is a writing system wherein the number of revolutions is constant. According to this system, since the number of revolutions is constant irrespective of a position of head, there are such advantages that high-speed search can be realized, simultaneous reading of data at a different position from that at which another data is written is possible, and the spindle servomechanism is simplified. Disadvantages are that the shortest writing wavelength is determined by the innermost radius, so that it is not suitable for high-density writing of data.
CLV system is a writing system wherein linear velocity is constant. According to this system, there are such advantages that since relative velocity is constant throughout a disk, writing wavelength is constant, so that it is suitable for high-density writing of data. Disadvantages are since the number of revolutions varies dependent upon a position of head, it is unsuitable for high-speed search, simultaneous reading of data at a different position from that at which another data is written is impossible, and spindle servomechanism is complicated.
A writing system of information obtained by combining a CAV system with a CLV system has been also proposed. In this system, the number of revolutions in a disk is made constant, and an amount of information to be written into one track is allowed to increase in proportion to its radius. In other words, since the number of revolutions is constant, this system results in a variable clock writing system wherein the writing bit rate is increased in proportion to radius and variable clock reading system. According to this combined system, writing wavelength is constant throughout a disk and the number of revolutions of the disk is constant, resulting in advantages. Such as the ability to perform high-speed search simultaneous reading of data at a different position from that at which another data is written and simplification of the spindle servomechanism.
FIGS. 1
to
3
are diagrams each showing a constitution of tracks. In this case, data to be written is, for example, image data which has been subjected to fixed length coding in frame, and 1 frame is composed of 8 blocks (hereinafter referred to as “single block SB”). Further, the total track number is made to be 80 tracks. The storing area is divided equally into 10 sections in the track direction to be 8 tracks per 1 storing region (hereinafter referred to as “clock block CBLK”).
Data of ⅞ frame per 1 track, total 7 frames is written in CBLK
0
which is the innermost radius, data of 1 frame per 1 track, total 8 frames is written in CBLK
1
, data of {fraction (9/8)} frames per 1 track, total 9 frames is written in CBLK
2
, in the following, the number of storing frames per 1 track is increased by each ⅛ frame in every CBLKs, and finally data of 2 frames per 1 track, total 16 frames is written in CBLK
9
being the outermost radius. A track number is designated by reference numeral
351
, a frame number is designated by reference numeral
352
, and a clock block number is designated by reference numeral
353
in the figures. As indicated in these figures, data can be written into total 115 frames extending from frame
0
to frame
114
and reading such data therefrom at the constant number of revolutions, besides, the shortest writing wavelength becomes substantially constant.
Moreover, although a manner for writing data differs from that described above, there is a manner for writing information called by the name of land/groove writing information wherein information is written by utilizing both sides of land and groove of disk track. When information is written in accordance with this manner, two times higher writing density than that of a conventional land writing or groove writing manner can be obtained, whereby extension of a writing period of time can be realized. An example of spiral track for land/groove writing information is shown in
FIG. 4
, and as a constitutional diagram of tracks thereof is shown in
FIG. 5
wherein reference numeral
361
designates land track, and reference numeral
362
denotes groove track.
As shown in
FIG. 4
, when the optical head jumps once backwardly from land to groove per 1 track or from groove to land by 1 track, the same processing as a usual one occurs wherein only grooves exist becomes possible.
When actually writing information shown in
FIGS. 1
to
3
, the number of revolutions of a disk must be adapted to be capable of writing information of ⅞ frame in 1 track in order to match the number of revolutions to that of the innermost radius which must be fastest. More specifically, when it is assumed that frame frequency is 29.97 Hz, the number of revolutions must be 34.3 rps which is induced from 29.97×8/7. According to the manner for writing information as described above, there is no problem in such a case as illustrated above wherein information of ⅞ frame is written into 1 track at the innermost radius. However, when information of {fraction (2/8)} to ⅜ frame is intended to write into 1 track, the number of revolutions becomes 80 to 120 rps, so that the value becomes difficult to realize. Moreover, since the number of revolutions is determined by the innermost radius, the innermost radius is not so extensively utilized towards inner radius.
Namely, when such a definition that CBLK-
1
, CBLK-
2
, . . . , is positioned on more inner radius than CBLK
0
in
FIG. 1
is continued, {fraction (6/8)} frame, ⅝ frame, . . . must be adapted to be capable of writing information in 1 track. Thus, there has been such disadvantage that the number of revolutions of a disk increases in such fashion of 40 rps, 48 rps, . . . , so that a storing region is restricted at a certain position in the disk due to the number of revolutions.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a method and an apparatus for writing information into an optical disk and reading it therefrom in which a writing capacity of the disk can be increased by realizing simultaneously writing of information at a constant number of revolutions with writing of information at a constant wavelength in the disk at a low rate.
According to a first feature of the invention, a method is provided for writing information into an optical disk and reading it therefrom, which comprises the steps of:
rotating an optical disk for writing data transmitted from a higher rank device at a constant rate (disk driving step);
producing a variable clock which varies a write or read clock for each of a plurality of storing regions defined from the inner circumference side toward the outer circumference side of the disk driven at a constant rate (variable clock production step); and
writing or reading data according to the clock produced for each storing region in the variable clock production step (write/read step),
wherein the write/read step comprises temporarily storing data, to be written or read, according to a difference between the rate of data input into or output from the higher rank device and the data write/read rate determined for each of the plurality of storing regions (buffer step).
According to a second feature of the invention, an apparatus is provided for writing info
Edun Muhammad
McGuireWoods LLP
NEC Corporation
LandOfFree
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