Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
2000-04-19
2004-06-08
Tran, Thang V. (Department: 2653)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
Reexamination Certificate
active
06747931
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for discriminating a type of an optical recording media, and more particularly, to a method for discriminating types of optical recording mediums having different structures.
2. Description of the Background Art
Optical recording mediums, that is, optical disks, includes a ROM type for reading only, a WORM type capable of recording by one time, and a rewritable type disk capable of recording repeatedly.
The ROM type optical disk includes a compact disk read only memory (CD-ROM) and a digital versatile disk read only memory (DVD-ROM). The WORM type optical disk includes a recordable compact disk (CD-R) that is capable of recording by one time and a recordable digital disk (DVD-R) that is capable of recording by one time.
The disk capable of recording repeatedly includes rewritable compact disk (CD-RW) and a rewritable digital versatile disk (DVD-RW, DVD-RAM). Difference of the two is that in case of the DVD-RAM, data is recorded in both of a land and a groove, while, in case of the DVD-RW, data is recorded in the groove.
The various optical disks include a low reflection type disk and a high reflection type disk. Especially, the CD-R includes a metal group disk and a coloring group disk.
Meanwhile, a light source in use for an optical pick-up for DVD has a wave length of 635~650 nm (visible light, red color), and in order to read data from the CD-R, a light source having a wave length of 780 nm (infrared light) is required. In this respect, the data recorded in the CD-ROM can be read by the wave length of either 780 nm or 635~650 nm.
The DVD group disk has more compact recording density and shorter distance from the surface of the disk to the data recording face compared to the CD disk. The actual distance from the disk surface of the DVD disk to the data recording face is 0.6 mm, while that of the CD disk is 1.2 mm.
FIG. 1
is a schematic view showing a general construction of an optical recording/reproducing device which is capable of recording data in an optical disk and reproducing the recorded data therefrom.
As shown in the drawing, an optical pick-up
102
renders a light beam collected on an objective lens under the control of the servo controlling unit
106
to be placed on a signal track of an optical disk, collects again the light reflected on the signal recording face, and makes incident on an optical detector (not shown) to detect various signals.
The optical detector includes a plurality of optical detect devices. Electric signals in proportion to the quantity of light obtained by each optical detection device are outputted to an RF and servo error generation unit
104
. The RF and servo error generation unit
104
detects an RF signal for reproducing a data, a focus error signal FE for servo-controlling or a tracking error signal TE from the electric signal outputted from the optical detector. The RF signal is outputted to a decoder
105
so as to be reproduced, and the servo error signal such as the FE and the TE are outputted to the servo controller
106
. And, the control signal for recording a data is outputted to an encoder
103
.
The encoder
103
encodes a data to be recorded to a recording pulse of a format as required by the optical disk
101
and records it in the optical disk
102
through the optical pick-up
102
. The decoder
105
restores an original data from the RF signal.
A host such as a PC may be connected to the optical recording/reproducing device. The host transfers a recording/reproducing command through an interface
110
of the optical recording/reproducing device to a MICOM
111
, transmits a data to be recorded to the encoder
103
, and receives a reproduced data from the decoder
105
. The MICOM
111
controls the encoder
103
, the decoder
105
and the servo controlling unit
106
according to the recording/reproducing command.
As to the interface
110
, an ATAPI (advanced technology attached packet interface) is typically used. The ATAPI refers to an interface standard between the optical recording/reproducing device such as a CD drive or a DVD drive and the host, which was proposed to transmit a data decoded in the optical recording/reproducing device to the host. The ATAPI serves to transmit the decoded data according to a protocol as defined in the host.
The servo controlling unit
106
processes the focus error signal FE and outputs a drive signal for focussing-controlling to a focus servo drive unit
107
, and processes the tracking error signal TE and outputs a drive signal for tracking-controlling to a tracking servo drive unit
108
. The focus servo drive unit
107
drives a focus actuator of the optical pick-up
102
to move the optical pick-up
102
upwardly and downwardly so that the optical disk
101
is rotated, tracing the up-down movement of the optical pick-up. That is, the focus actuator, which drives the objective lens collecting the light upwardly and downwardly, that is, in the focus axis direction, maintains evenly the distance between the objective lens and the optical disk
101
according to the focus control signal.
The tracking servo drive unit
108
drives the tracking actuator of the optical pick-up
102
, according to which the objective lens of the optical pick-up
102
moves in the radial direction to the optical disk, thereby correcting a position of the light beam and following a predetermined track.
If the optical recording/reproducing device is a CD drive, what is needed is to discriminate a type of CD, that is, whether it is a high reflection disk or a low reflection disk. But, if it is the DVD drive (i.e., DVD-RAM system), it should be able to reproduce CD group disk as well as DVD group disk, considering that CD group software is vastly used.
Therefore, when the optical disk is inserted, it is necessary for the DVD drive to discriminate whether the inserted disk is the CD group disk or the DVD group disk, whether the discriminated disk in the same group is of a low reflection or a high reflection, or whether it is a reproducing-only type or a recordable type, so that the DVD drive can perform a suitable servo operation. Namely, without discriminating types of the disk, the servo wouldn't be operated properly and it takes a long time to stabilize the servo operation. The reason for this is that servo error signal characteristics are different for disk types.
In this respect, since the RF level of the optical disk is different in terms of reflectivity, in the conventional art, whether it is a low reflection or a high reflection is judged by sensing the RF level. For example, in case of the DVD group disk, the size of the RF level is as follows: DVD-ROM>DVD-RW>DVD-RAM.
However, as to the method for discriminating types of disks of the conventional art, the reflectivity of the high reflection disk may be lowered down, and if it is actually lowered down for a cause, there is a high possibility that the lowered-down high reflection disk is misjudged as a low reflection disk.
In addition, since deflections are wide-ranged for disks, it may occur that there is no difference between RF levels of different disks. Especially, in case of the CD-R and the CR-ROM, since the both have a great reflectivity, it is not easy to set a threshold value for differentiating the two disks.
As described above, the method for discriminating types of disks by using the RF level of the conventional art has the problem in that an error may occur in differentiating disks, making it difficult to discriminate disks accurately. In addition, it takes a long time to stabilize the servo operation, degrading the performance of the system.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a method for discriminating a type of an optical recording medium which is capable of discriminating a DVD group disk and a CD group disk on the basis of a reference level of a focus search wave form.
Another object of the present invention is to provide a method for discriminating a type of an optical record
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
Tran Thang V.
Vuong Bach
LandOfFree
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