Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Reexamination Certificate
1998-09-29
2001-04-17
Tran, Thang V. (Department: 2651)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
C369S053130
Reexamination Certificate
active
06219318
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an optical disc drive for playing back or recording and playing back an optical disc and a method of compensating the time information obtained from the optical disc.
2. Description of the Prior Art
There are known optical disc drives for recording and playing back a recordable-type optical disc such as a CD-R (CD-Recordable), examples of which include CD-R drives.
In such optical discs to which data can be newly written and from which the written data can be read out, there are formed a spiral pre-groove (WOBBLE). The pre-groove meanders at a predetermined frequency, and ATIP (Absolute Time In Pre-groove) information (time information) is recorded with the pre-groove.
In these optical disc drives, a WOBBLE signal is obtained from reflected light from the pre-groove, and then ATIP information is obtained (extracted) from the WOBBLE signal. The time information in the ATIP information is utilized to specify a position on the optical disc (determined by the absolute time) or the like.
However, the time information is likely to be deteriorated due to noises from the circuits or flaws or dusts on the disc or the like, because the time information is obtained from the WOBBLE signal. Therefore, there is a case that it is not possible to acquire time information, so that time information is missing (by which continuousness of the time information is lost).
When such missing of time information would occur, the control means in the optical disc drive can not acuire the absolute time at that position. As a result, there is a case that it is not possible to specify a recording start position (a recording start time) or a recording end position (recording end time) or the like when a recording is to be carried out onto the optical disc. Further, when the recording start position or the recording end position is not specified, there arises a case that recording is carried out over the recording start time or the recording end time. Furthermore, at the worst, there is a case that recording can not be carried out at all.
SUMMARY OF THE INVENTION
In view of the problem described above, it is an object of the present invention to provide an optical disc drive which can specify a position on the optical disc (absolute time) reliably and accurately.
In order to achieve the object, the present invention is directed to an optical disc drive for recording and playing back a recordable-type optical disc having a pre-groove which carries time information representing a position on the optical disc. The optical disc drive comprises:
a driving mechanism for rotating the optical disc;
an optical pick-up for writing and reading data to and from the optical disc;
signal processing means for processing signals read out from the optical disc by means of the optical pick-up;
control means for controlling at least the driving mechanism, the optical pick-up and the signal processing means;
time information acquiring means for acquiring the time information based on a signal from the optical pick-up which receives reflected light from the pre-groove; and
time information compensating means for compensating the time information.
According to the optical disc drive described above, even if there is a case that time information such as an ATIP-SYNC signal could not be obtained from the optical disc, it is compensated by the signal produced by the time information compensating means. Therefore, it is possible to maintain the continuousness of the time information.
As a result, it is possible to accurately specify a recording start position (recording start time) and a recording end position (recording end time), and therefore recording can be carried out more reliably and accurately.
Preferably, the time information compensating means is constructed so as to generate a signal equivalent to the time information acquired by the time information acquiring means and then use the generated signal as time information as necessary.
Another aspect of the present invention is directed to an optical disc drive for recording and playing back a recordable-type optical disc having a pre-groove which carries time information representing a position on the optical disc, in which the optical disc drive comprises:
a driving mechanism for rotating the optical disc;
an optical pick-up for writing and reading data to and from the optical disc;
signal processing means for processing signals read out from the optical disc by means of the optical pick-up;
control means for controlling at least the driving mechanism, the optical pick-up and the signal processing means;
a first synchronizing signal generating means for generating a first synchronizing signal based on a signal from the optical pick-up which receives reflected light from the pre-groove; and
a second synchronizing signal generating means for generating a second synchronizing signal which has the same cycle as that of the first synchronizing signal;
synchronizing means for synchronizing the first synchronizing signal with the second synchronizing signal;
time information acquiring means for acquiring the time information corresponding to the first synchronizing signal based on signal from the optical pick-up which receives reflected light from the pre-groove; and
a memory for storing the time information, wherein the stored time information is rewritten in synchronization with the second synchronizing signal which is synchronized with the first synchronizing signal.
In this aspect, it is preferred that the time information acquiring means is constructed so as to acquire the time information after the first synchronizing signal has been synchronized with the second synchronizing signal.
Further, it is also preferred that the time information stored in the memory is used in the case where an abnormality arises in the first synchronizing signal or in the case where an abnormality arises in the time information corresponding to the first synchronizing signal.
Furthermore, it is also preferred that the second synchronizing signal generating means includes a clock provided in the optical disc drive.
The other aspect of the present invention is directed to a method of compensating time information obtained from an optical disc. The method comprises the steps of:
acquiring a first synchronizing signal and time information corresponding to the first synchronizing signal from a recordable-type optical disc having a pre-groove which carries the time information representing a position on the optical disc;
storing the time information in a memory provided in an optical disc drive;
generating a second synchronizing signal which is synchronized with the first synchronizing signal in the optical disc drive;
renewing the time information stored in the memory at the timing of cycle of the second synchronizing signal; and
compensating the time information with the renewed time information stored in the memory in the case where the first synchronizing signal or the time information corresponding to the first synchronizing signal can not be acquired from the optical disc.
In this method, it is preferred that the second synchronizing signal generating means includes a clock provided in the optical disc drive.
Other objects, structures and advantages of the present invention will be apparent when the following description of the preferred embodiment is considered taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5363360 (1994-11-01), Fairchild
patent: 5463607 (1995-10-01), Roth et al.
patent: 5506824 (1996-04-01), Fairchild et al.
patent: 5508985 (1996-04-01), Fairchild et al.
Mitsumi Electric Company Ltd.
Patents+TMS
Tran Thang V.
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