Dynamic information storage or retrieval – Information location or remote operator actuated control – Selective addressing of storage medium
Reexamination Certificate
2000-09-19
2003-05-20
Dinh, Tan (Department: 2651)
Dynamic information storage or retrieval
Information location or remote operator actuated control
Selective addressing of storage medium
C369S030270
Reexamination Certificate
active
06567350
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control adjustment method for a reproduction/recording apparatus for a disc-shaped recording medium which performs real-time reproduction/recording of audiovisual (AV) data, such as television broadcasting. The present invention also relates to a reproduction/recording apparatus for a disc-shaped recording medium.
2. Description of the Related Art
Optical discs are now available as reproduction/recording mediums used in reproduction/recording apparatuses, such as optical disc video recorders. Data is reproduced from or recorded to an optical disc by focusing light which is emitted from a semiconductor laser onto an information surface of the disc so that the light converges on a micro-scale spot with a diameter of 1 micron or less. As a high-density, mass storage recording medium, such an optical disc has random access characteristics better than that of conventional tape media. In addition, a noncontact reproduction/recording using a laser beam reduces deterioration due to repeated use, thereby enabling disc manufacturers to mass-produce low-cost duplications by means of mastering.
CDs are an example of optical discs, which has replaced the conventional analog record and has become popular as a high quality-sound digital audio medium. Also in recent years, DVD has been commercialized as a high quality digital image-recording medium. In view of these trends, it is predictable that optical discs will develop further in the future as digital recording media for AV data.
CDs and DVDs are reproduction-only optical discs, on which data is pre-recorded. On the contrary, recordable optical discs have been developed in recent years, on which users can record AV data at home. An example of such an optical disc is DVD-RAM. Furthermore, in order to reproduce/record television programs, for example, from/to these recordable optical discs apparatuses such as optical disc video recorders are now under development. These video recorders are now regarded as novel products which will replace conventional video tape recorders such as VHS.
For such a reproduction/recording apparatus for performing noncontact recording/reproduction and capable of high density recording, it is indispensable to employ: a tracking control technique for making the laser beam stably follow lands or tracks provided in advance on the media; a focus control technique for forming the micro-scale spot; and a laser power control technique for achieving a laser output with a stable power. As the recording density becomes higher, more accuracy is required for these techniques.
In order to improve the accuracy of the aforementioned control techniques, control adjustments have been incorporated into the reproduction/recording apparatuses, in order to adjust the control of the reproduction/recording apparatuses in response to environmental changes such as a temperature change inside the reproduction/recording apparatus. According to such a control adjustment, when the temperature inside the apparatus changes, a process of control adjustment in response to the ambient temperature around or the internal temperature inside the apparatus is performed, even in recording or reproduction, so that the control corresponds to the changes in circuit characteristics and the output power of the semiconductor laser, which depends on temperature. By performing such a control adjustment, a more accurate control is achieved.
The above control adjustment method regarding temperature change will now be described in detail with reference to
FIGS. 1
to
3
.
FIG. 1
is a plan view of the recording surface of an optical disc
100
, which is a disc-shaped recording medium. The optical disc
100
is provided thereon with a data region
101
and a lead-in region
102
. The data region
101
includes regions for recording audiovisual (AV) data, and the lead-in region includes control tracks for recording disc management information and a test region
104
for performing control adjustments. Although not shown in
FIG. 1
, a plurality of tracks for recording data are formed on the recording surface of the optical disc along circumference direction. Each track is divided into a plurality of sectors, each of which is the basic unit for data reproduction/recording.
An example of AV data to be recorded on the data region
101
is program information such as a TV broadcast. On an optical disc capable of random access, a single program may be divided into a plurality of portions and recorded to a plurality of regions as a result of repeated recording and deleting. For example,
FIG. 1
shows a case where a single program information is recorded to three regions
103
a
,
103
b
, and
103
c.
Data recording to the optical disc of
FIG. 1
will now be described.
Data a to be recorded is first recorded to the region
103
a
, thereby becoming recorded data a. The next data is recorded to the region
103
b
, and in order to achieve this recording, an optical head for recording, which is provided in the reproduction/recording apparatus, has to be moved from the region
103
a
to the region
103
b
. This is called a seek operation. Herein, the term “seek” includes not only the movement of the optical head to a target track for reproduction/recording but also the holding of the optical head until the target sector reaches the optical head by the disc rotation. Furthermore, in the case of a CLV method or a ZCAV method, in which the rotation speed of the disc is changed for the reproduction or recording, the term “seek period” means not only the time required for the seek operation as described above but also the time required before the next reproduction/recording can be performed. This includes the setting time before the rotation speed of the disc motor reaches an appropriate speed for reproduction/recording.
After the execution of the seek operation, data b to be recorded is recorded to the region
103
b
, thereby becoming recorded data b. Next, the seek operation from the region
103
b
to the region
103
c
is performed, and the data c to be recorded is recorded to the region
103
a
, thereby becoming recorded data c. Accordingly, seeks and recordings are repeated so as to divide and record continuous single AV data to a plurality of regions.
The data to be recorded during the seek operation is temporarily stored in a semiconductor memory of the reproduction/recording apparatus, and then recorded to a recording region after the seek operation is completed.
FIG. 2
is a buffer model illustrating the quantity of data temporarily stored in the semiconductor memory during the recording of the data a, b, and c, to the respective regions
103
a
,
103
b
and
103
c
. In
FIG. 2
, the horizontal axis represents time and the vertical axis represents the stored data quantity.
During the period
201
, the data a is first recorded. The data is recorded at a faster speed than the data generating speed, and therefore the quantity of data stored in the semiconductor memory decreases. Eventually, the data is recorded immediately after it is generated. After the data a is recorded, a seek operation for recording the data b is performed during the period
202
. During the seek operation, a data recording on the disc is impossible, and therefore all of the generated data is temporarily stored in the memory, and the stored data quantity increases. When the seek is completed, the stored data quantity reaches the maximum value A in FIG.
2
.
After the optical head reaches the region
103
b
for recording the data b, the data stored during the seek period
202
is recorded, as well as the data b, in the period
203
. The data is recorded at a faster speed than the data generating speed, and therefore the quantity of data stored in the semiconductor memory decreases. Eventually, the stored data quantity is close to zero, and thereafter the data is recorded almost immediately after it is generated.
In the period
204
, a seek operation for recording the data c is performed, as in the seek period
2
Ide Hirofumi
Ishibashi Kenzo
Kawashima Keiichi
Sugimoto Hiroshi
Takagi Yuji
Dinh Tan
Matsushita Electric - Industrial Co., Ltd.
Renner Otto Boisselle & Sklar
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