Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Reexamination Certificate
1999-03-29
2001-07-10
Edun, Muhammad (Department: 2651)
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
C369S053130, C369S047360
Reexamination Certificate
active
06259669
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from applications for OPTICAL DISC RECORDING APPARATUS AND METHOD FOR IMPROVING THE CHARACTERSTICS OF CROSS ERASURE earlier filed in the Korean Industrial Property Office on the Mar. 27, 1998 and there duly assigned Ser. No. 10795/1998, and for OPTICAL DISC RECORDING APPARATUS AND METHOD FOR IMPROVING THE CHARACTERISTICS OF CROSS ERASURE earlier filed in the Korean Industrial Property Office on the Jan. 20, 1999 and there duly assigned Ser. No. 1644/1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical disc recording technique, and more particularly, to a technique for reducing cross erasure in an optical disc recording apparatus by controlling the laser power during rewriting in a land/groove recording and reproducing technique.
2. Description of the Related Art
An optical disc, used as a noncontact information recording medium in an optical disc player, has been developed for high capacity, high speed, and high density recording with advancements in the information field. In particular, an optical disc capable of recording/reproducing high density information, such as a digital versatile disc (DVD), a random access memory (RAM), etc., has been actively developed in association with the recording/reproduction of image information in a multimedia PC or a high quality TV. Thus, a high-density optical disc medium having an improved capacity must be developed to handle the next generation multimedia market.
The recording density per unit area must be increased to manufacture a high-density optical disc. The recording density can be increased by reducing the size of a laser spot. The size of the laser spot is proportional to the wavelength &lgr; of a light beam and inversely proportional to the numerical aperture. Hence, in order to reduce the size of the laser spot, the wavelength of the beam must be reduced, or an objective lens having a high numerical aperture must be used.
The interval between the tracks of a high-density optical disc is gradually decreasing through the use of these methods.
An optical disc capable of recording information on lands and grooves formed thereon has already been proposed as an alternative to increasing the recording density within a limited recording area on an optical disc.
Typically, such an optical disc has a plurality of tracks formed from the inner circumference toward the edge of the disc in a spiral. Grooves are formed to predetermined depths on each track, and lands are formed to the surface height of the disc thereon. These lands and grooves alternate between adjacent tracks. A mark representing data information is formed on the lands and grooves by the power of a laser corresponding to a recording pulse pattern.
In a disc drive using this high-density optical disc as a recording medium, a recording pulse pattern depending on the recording states of nonoverwritten and overwritten tracks is represented as a record peak power and an erase power. However, for such a recording pattern, all domains with recording and erasing power are heated during overwriting. Thus, in the case of the land/groove recording method, e.g., when data is recorded in the grooves, cross erasure occurs, in which data recorded between adjacent lands is erased by generated heat, even in the recording section of a portion where nonoverwritten and overwritten erasing areas overlap each other. Therefore, the reliability of data between adjacent tracks is degraded.
SUMMARY OF THE INVENTION
To solve the above problem, it is an objective of the present invention to provide an optical disc recording apparatus for reducing cross erasure by generating less than a reproduction power, when an erasing portion before overwriting overlaps an erased portion during overwriting.
Accordingly, to achieve the above objective, there is provided an optical disc recording apparatus for reducing cross erasure when recording on an optical disc capable of being overwritten, the apparatus comprising: a pickup having a laser; a recording/reproduction signal processing unit; a servo unit; and a control unit. The control unit comprises: a control signal generator for comparing a reproduction signal, reproduced from a recording track in the recording/reproduction signal processing unit in a recording mode, with a modulated recording signal to be recorded, and generating a first control signal when only the reproduction signal has a recording mark, a second control signal when neither the reproduction signal nor the modulated recording signal have the recording mark, and a third control signal when only the modulated recording signal has the recording mark; and a laser pulse controller for controlling the power of the laser so that the laser generates power at a first erasing level when the first control signal is supplied, generates power at a second erasing level lower than the first erasing level when the second control signal is supplied, and generates a predetermined multi pulse power when the third control signal is supplied.
To achieve the above objective, there is also provided an optical disc recording method for reducing cross erasure when recording on a recordable/reproducible phase changing optical disc using laser power, the method comprising the steps of: (a) determining whether the optical disc drive is in a recording mode; (b) determining whether erasing areas overlap each other by comparing a pattern recorded on a recording track with a pattern to be recorded when it is determined in step (a) that the optical disc drive is in the recording mode; and (c) controlling the laser to generate a first predetermined erasing power when it is determined in step (b) that the pattern to be recorded is the erasing area and the recorded pattern is an area having a recording mark, and to generate a second erasing power that is lower than the first erasing power when both the pattern to be recorded and the recorded pattern are the erasing area.
REFERENCES:
patent: 5448551 (1995-09-01), Miyagawa et al.
patent: 5848045 (1998-12-01), Kirino et al.
patent: 6-290460 (1994-10-01), None
patent: 10-208246 (1998-08-01), None
patent: 10-289461 (1998-10-01), None
Lee Kyung-Geun
Yoon Du-seop
Bushnell , Esq. Robert E.
Edun Muhammad
Samsung Electronics Co,. Ltd.
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