LG Electronics GSA-4165B, GSA-4168B, GSA-4167B service manual Writing Process of DISC

Reflected recording pulse

Incident recording pulse

2) ROPC (Running Optimum Power Control)

• Variable primary factor of Optimum Power

–Change of Power sensitivity on the Disc. (limited to 0.05 *Po)

–Wavelength shift of the laser diode due to the operating temperature change.

–Change of the Spot aberration due to the Disc skew,

Substrate thickness, Defocus.

– Change of Disc or Optics conditions due to the long term OPC

==> It is necessary to adjust continuously to obtain the Optimum Power.

• Principle of Running OPC	Sampled timing B
– To meet the factors mentioned above,
a horizontal _ direction movement of a curve is uesd.

– Beta = f(B-level) = constant on the Recorded Disc

–Procedure of ROPC

a. Reference B-level is determined during OPC Procedure.

b. During Recording, B-level value is controlled to have a close Reference B-level value.

c. Normalization of B-level is used to eliminate the effect of reflectivity fluctuation. ==> The reflected B-level value is normalized by the disc reflectivity itself.

	B
Sample Disc Reflectivity	Level	Sampled at timing B
(Read power)
		normalized to recording power
11T
		Level B with Pwo
Sample B-level (Write Power)		Pwo decided by OPC
		Recording Power

10. Writing Process of DISC

CD-R/RW Media Program Area

Write Strategy	PMA Area
Determination

OPC PCA Test Area Lead-In Area

ROPC

PCA Count Area Lead-outArea

* Recording Capacity of CD-R/RW (74Minute Recording media)

•(2048 Byte/Sector) X (75 Sector/Second) X (60 Second/Minute) X 74 Minute = 681,984,000 Bytes = 682 Mbytes

•But the actual recording capacity is about 650 Mbytes. (according to the ISO 9660 standard, approximately 30 Mbytes are used to make directory structure and volume names.)

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