Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
1998-08-10
2001-06-05
Huber, Paul W. (Department: 2651)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S116000
Reexamination Certificate
active
06243342
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of Korean Application No. 38439/1997, filed Aug. 12, 1997, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical disk system, and more particularly, to a method and apparatus for controlling an optical output by using a laser diode.
2. Description of the Related Art
In an optical recording/reproducing technique for recording and reproducing data on an optical disk by using a laser, the data is read out by a change in light reflected from the disk. In order to change the reflected light, that is, to record the data on the disk, a compact disk (CD) or a digital video disk (DVD) utilizes the interference between a pit curved inwards from a substrate and a reference surface. A magneto-optical disk uses a method for changing the direction of polarized light of a magneto-optical recording material. Moreover, a phase-change type disk uses a difference between the quantities of reflected light according to the state of a recording material. A CD-recordable (CD-R) disk utilizes a change in an organic pigment. Each disk is classified into a read-only type, a write-once type and an overwritable type. In an optical disk system using such an optical disk, an optical pickup is an essential component to record or reproduce data on the optical disk by controlling an optical output.
FIG. 1
illustrates a conventional laser diode optical output controlling apparatus. The apparatus of
FIG. 1
includes a register controller
2
, a digital-to-analog (D/A) converter
4
, a current driver
6
, a laser diode
8
, a photo diode
10
, and a current-to-voltage (I/V) converter
12
.
An optical pickup designer selects digital values suitable for reproducing and recording optical outputs in consideration of the characteristics of the laser diode
8
. The digital values are stored in respective registers within the register controller
2
. The digital value of the reproducing or recording optical output stored in one of the registers within the register controller
2
is converted into an analog current value by the D/A converter
4
, and the analog current value is applied to the current driver
6
. The current driver
6
drives the laser diode
8
according to the analog current value. Namely, the current driver
6
amplifies the applied current value to supply reproducing or recording current of a desired value to the laser diode
8
. Then the laser diode
8
irradiates a laser beam onto an optical disk (not shown) at a predetermined reproducing/recording optical output level. The laser beam is also irradiated to the monitoring photo diode
10
, which is opposite to the laser diode
8
. The current of the optical output received by the photo diode
10
is converted into a voltage by the I/V converter
12
, and the converted voltage is applied to the register controller
2
. The register controller
2
calculates an accurate value by comparing the reproducing or recording optical output with the irradiated optical output only once and stores the calculated value in the register. That is, the accurate value is set by comparing the optical output applied from the I/V converter
12
with the optical output stored in the register only once, and the accurate value is again stored in the register. Thus, the actual optical output of the laser diode
8
is controlled by using the stored value only.
However, during continuous recording, the laser diode generates heat. Therefore, even if constant current is supplied to the laser diode by the register in which a desired value is stored, the efficiency of the optical output of the laser diode is lowered and the optical output of the desired amount is not irradiated. Therefore, sufficient light is not supplied to regions of the disk, and data may be not recorded. Even though data is recorded, the data may not be recorded accurately. Consequently, a carrier-to-noise (C/N) ratio is lowered and the reliability of the recording/reproducing optical disk system is degraded.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optical output controlling method and apparatus for improving the performance of a recording/reproducing optical disk system even during continuous optical outputs of a laser diode.
It is another object of the present invention to provide an optical output controlling method and apparatus for maintaining an optical output of a constant quantity, so that a constant optical output of the laser diode which is initially set is continuously maintained.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention.
According to an aspect of the present invention, to achieve the above and other objects of the present invention, a writing or erasing optical output of a laser diode are controlled during a mirror region interval of a header within an optical disk, under a continuous optical output state of the laser diode. A change in an optical output caused by heat of the laser diode is compensated by comparing the writing or erasing optical output with a corresponding preset writing and erasing optical output value.
REFERENCES:
patent: 5042022 (1991-08-01), Ogawa
patent: 5548573 (1996-08-01), Takeuchi
Huber Paul W.
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
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