Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Reexamination Certificate
1994-04-08
2001-05-08
Young, W. R. (Department: 2651)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
C369S053180, C369S053280, C369S053370
Reexamination Certificate
active
06229775
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a driving method and apparatus for a light source element such as a laser diode, which is included in an optical pickup that performs data read/write operations for an optical disc.
Generally, optical discs have a helical track. Using a light source element such as a laser diode, recorded data is read out from or recorded in the track. The optical pickup provided with the light source element should correctly trace the track during the reading or recording of data. This is called tracking, and a tracking error signal is generated for tracking control. If a tracking error occurs during a data reading mode, the wrong data is read out. If a tracking error occurs during a writing mode, the data is recorded at the wrong position.
If the wrong data is read out, that data is abandoned, and the tracking operation is again performed for reading out the desired data. However, in the case of a writing mode, the data may be recorded at a position where other data has already been recorded, thereby losing data.
FIG. 1
is a block diagram illustrating a conventional driving apparatus for a light source element. The conventional apparatus includes a mode selector
101
, a reference power data generator
102
and a drive signal generator
103
.
In
FIG. 1
, mode selector
101
is for selecting the driving mode of an optical pickup and generates a mode signal M based on user manipulation. For example, the mode signal M may be a logic “low” when the driving mode is set for reading data and may be a logic “high” when the driving mode is set for writing data. Reference power data generator
102
generates reference power data PREF in accordance with mode signal M. Generally, a light source element requires less power for read operations than for writing. Besides varying in accordance with the driving mode, the power required for driving the light source element also varies according to the kind of optical disc used for reading/writing the data. Therefore, the reference power data suitable for a given optical disc should be recorded in the disc's lead-in area. Accordingly, based on the data read out from the optical disc, reference power data generator
102
generates reference power data which, in accordance with mode signal M, is either for a reading mode or for a writing mode. In other words, reference power data generator
102
generates a read reference power data for reading and a write reference power data for writing. The reference power data PREF is applied to drive signal generator
103
where it is converted into a driving signal DR and then applied to a light source element such as a laser diode installed in the optical pickup.
As described above, in the conventional driving apparatus of a light source element, the light source element is operated at a constant power irrespective of pickup position. Thus, even if the optical pickup is disposed in an incorrect position due to poor tracking, which may result from incorrect operation of the driving apparatus, an external impulse signal, minor impacts, disc imperfections, dust on the disc, etc., the light source element maintains a constant power level. Therefore, if a tracking error occurs during writing, the previously recorded data is lost by overwriting additional data.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a driving method for a light source element which alleviates the above problems.
The other object of the present invention is to provide a driving apparatus for a light source element which performs the above driving method.
To attain the object, the present invention provides a driving method for a light source element included in an optical pickup, comprising the steps of discriminating whether tracking error occurs, based on a tracking error signal generated in accordance with the movement of the optical pickup; and supplying the light source element with a driving signal having a level suitable for a data read operation irrespective of the driving mode of the optical pickup, when tracking error occurs; wherein the discriminating step further comprises a step for generating an error signal activated when a tracking error signal based on the movement of the optical pickup is higher than a first level or lower than a second level which is lower than the first level.
The driving method of the invention further includes the steps of detecting address data from the data read from the optical disc by the optical pickup and determining whether the detected address data corresponds to a desired address; and, if the detected address data corresponds to a desired address, converting the state of the error signal into a nonactive state.
To attain the other object of the invention, the driving apparatus for a light source element included in an optical pickup according to one aspect of the present invention, comprises: a mode selector for generating a mode signal corresponding to a user-selected read/write mode;
a reference power data generator for detecting write reference power data and read reference power data from the data read out from the optical disc, and outputting the detected data;
a first drive signal generator for generating a reading drive signal based on said read reference power data;
a second drive signal generator for generating a writing drive signal based on said write reference power data;
an error discriminator for receiving a tracking error signal generated in accordance with the movement of the optical pickup, and for generating an error signal which is active when tracking error occurs; and
a selector for selecting the reading drive signal if the error signal is active and otherwise selecting between the reading drive signal and the writing drive signal based on the mode signal, and supplying the light source element with the selected drive signal.
According to the preferred embodiment, the driving apparatus further includes a position discriminator for discriminating whether the optical pickup is located at a desired position based on the data read from the optical disc, wherein, if the optical pickup is located at a desired position, the error signal is converted into a nonactive state.
The error discriminator generates an error signal activated when the tracking error signal is higher than a predetermined first level or lower than a predetermined second level which is lower than the first level. The error discriminator comprises a first comparator for comparing the tracking error signal with the first level; a second comparator for comparing the tracking error signal with the second level; an OR gate for performing a logic OR operation with the output of the first comparator and the output of the second comparator; and a D flip-flop whose clock input port receives the output of the OR gate and whose data input port is coupled a supply voltage, which is reset by the output of the position discriminator.
The selector includes a logic operator for receiving the error signal and the mode signal to produce a selecting signal; and a multiplexer for selecting one between the outputs of the first and second drive signal generators in accordance with the output of the logic operator.
To attain the other object, the driving apparatus for a light source element included in an optical pickup according to another aspect of the present invention, includes a mode selector for generating a mode signal corresponding to a user-selected read/write mode;
a reference power data generator for generating a first reference power data whose level is varied in accordance with the mode signal and based on the data read out from the optical disc, and a second reference power data which is generated irrespective of the mode signal and is suitable for data read operations;
a first drive signal generator for generating a first driving signal based on the first reference power data;
a second drive signal generator for generating a second driving signal based on the second reference power data;
an error discriminator for receiving
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Young W. R.
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