Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2000-10-13
2002-08-13
Edun, Muhammad (Department: 2653)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S047280, C369S275300
Reexamination Certificate
active
06434091
ABSTRACT:
BACK GROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information record disc, such as an optical disc, which is used to record information, and more particularly relates to an information record disc, which has a wobbled record track and on which information can be additionally written and re-written. Moreover, the present invention relates to an information recording apparatus for recording information onto such an information record disc.
2. Description of the Related Art
A CD (Compact Disk) on which information can be recorded or written just once is typically known as a CD-R (CD-Recordable). Also, a CD on which information can be re-written a plurality of times is typically known as a CD-RW (CD-ReWritable). Record tracks of the CD-R and the CD-RW are slightly meandering or wobbling in a radius direction. This meandering condition of the record track is typically referred to as a “wobbling” or “wobble”.
On the other hand, in order to record information onto a disc or reproduce the information recorded on the disc, there is required the information for indicating an absolute address (or an absolute time) on the disc. Hereafter, this information is referred to as “pre-information”.
In case of the CD-R and the CD-RW, the pre-information is recorded on the disc by FM-modulating the wobble. Actually, a carrier signal used to form the wobble is FM-modulated in accordance with the pre-information. The wobble corresponding to a wave form of this FM-modulated carrier signal is formed on the record track. Accordingly, the pre-information is recorded on the disc.
When recording the information onto the CD-R or the CD-RW or when reproducing the information recorded on the CD-R or the CD-RW, a recording apparatus or a reproducing apparatus reads in the wobble formed on the CD-R or the CD-RW, and controls a rotation number of the CD-R or the CD-RW or generates a record track, in accordance with the information obtained from the wobble. For this reason, it is not desirable that the frequency of the wobble is widely changed. Thus, an amount is very slight which is allowable for the change in the frequency of the wobble, in order to superimpose the pre-information onto the wobble. For example, if the frequency of the wobble is 22.05 kHz, the amount is only ±1 kHz which is allowable for the change in the frequency of the wobble in order to superimpose the pre-information. Consequently, it is not easy for the recording apparatus or the reproducing apparatus to accurately detect the pre-information from the wobble. This results in a problem that the accuracy to specify a position on the disc is poor.
If the accuracy to specify the position on the disc is poor, a record position may be easily deviated when linking the new record information with the record information already recorded on the disc. Consequently, for example, there may be a case that the new record information is overwritten onto the already recorded information or that a gap which cannot be estimated is induced between the already recorded information and the new record information. In order to avoid such a case, in the CD-R and the CD-RW, a buffer region is reserved by recording dummy data following the record information when the operation for writing the record information is ended. However, this has a defect that the buffer region brings about a loss of a memory capacity of the disc.
On the other hand, a recordable DVD, such as a DVD-RAM and the like, uses a method different from those of the CD-R and the CD-RW to record the pre-information on the disc. That is, the recordable DVD employs a method of forming a pre-pit (embossed pit) on the disc to thereby record the pre-information on the disc.
However, this method has the configuration in which the pre-pit is formed only on the recordable DVD, which results in a largely structural difference between a disc dedicated to a reproduction and a recordable disc. Thus, it is difficult to attain a compatibility between both of them. For example, this brings about a problem that it is difficult for a common reproduction unit to reproduce the information recorded on the recordable disc having the pre-pit and also reproduce the information recorded on the disc which is dedicated to the reproduction and does not have the pre-pit.
SUMMARY OF THE INVENTION
The present invention is proposed in view of the above mentioned problems. It is therefore an object of the present invention to provide an information record disc, which can easily attain a compatibility between a record disc dedicated to a reproduction and a recordable record disc and also which can allow to detect a record position of record information on a disc easily and accurately, as well as an information recording apparatus, which can detect a record position of record information on a disc easily and accurately.
The above object of the present invention can be achieved by an information record disc provided with: a track formed on a disc surface, on which record information to be reproduced is recorded or to be recorded; and a wobble formed on the track such that a phase of the wobble is changed at a plurality of locations on the track and that positional information indicative of a position on the disc surface is recorded as a change in the phase of the wobble. The record information is arranged at a predetermined arrangement cycle, and includes a synchronization signal to attain a synchronization when the record information is recorded or reproduced. An interval at which the phase of the wobble is changed on the track is equal to N times (N is an integer equal to or greater than 1) of the predetermined arrangement cycle of the synchronization signal when the record information is recorded on the track.
According to the information record disc of the present invention, when the record information is recorded on the track, the interval at which the phase of the wobble is changed is equal to N times of the predetermined arrangement cycle of the synchronization signal. This implies that a certain positional relationship exists between the position at which the phase of the wobble is changed and the position at which the synchronization signal in the record information is placed. Thus, on the basis of such a certain positional relationship, just by detecting the change of the phase of the wobble, the position at which the synchronization signal is recorded or the position at which the synchronization signal is to be recorded can be specified or identified easily. Therefore, it is possible to easily specify or identify the position at which the record information is to be recorded on the disc.
Further, since the positional information indicative of the position of the disc surface is recorded as the change of the phase of the wobble, it is possible to record the positional information clearly while maintaining the frequency of the wobble constant. Therefore, while satisfying such a demand that the information obtained from the wobble is used for the rotation control of the disc and the generation of the record clock, it is possible to improve the detection accuracy of the positional information. Further, it is possible to accurately detect the change of the phase of the wobble, and thereby accurately detect the record position of the record information on the disc.
As detailed above, according to the information record disc of the present invention, it is possible to specify the record position of the information on the information record disc easily and accurately. Thus, it is possible to prevent the new record information from being overwritten to the already recorded information, without reserving the buffer region by using the dummy data and the like. Thus, it is possible to exclude the unnecessary usage of the memory region on the information record disc, and also possible to substantially increase the memory capacity of the information record disc.
In addition to such effects, according to the information record disc of the present invention, it is possible to easily attain the
Edun Muhammad
Morgan & Lewis & Bockius, LLP
Pioneer Corporation
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