Differentiation Of Disk Type; 3-5-L. Cdldvd Differentiation; Dl Differentiation; Differentiation - Sony DVP-M35 Operation Manual

3-5. Differentiation of Disc Type
This series can determine three types of discs (CD/DVD-SL/DVD-DL)
when performing focus-search.
3-5-l. CD/DVD Differentiation
The pit shape and track pitch are quite different between CD and DVD. Because of this
difference, TE is not generated even if a large laser spot for CD is shot at a high density
disk such as DVD. This feature is utilized to judge CD or DVD.
Specifically, even if DVD is played in the CD mode (the optical pickup operates at the
CD side), TE is not generated almost all.
On the other hand, by playing CDs in the CD mode, naturally, the 2Vp-p traverse
waveform (approx.) will be measured. This is used for the detection.
3-S-2. SL/DL Differentiation

3-5-3. Differentiation

1) The servo system mode is CD (MB-78 board: IC452 "@"P and "@' are "L")
2) PI mode is DVD (MB-78 board: IC452 @P is '?I")
3 ) Both lasers turn ON
4) The spindle turns ON
5) The sled is moved to the external circumference slow.
6) Both focus actuators are moved up and down.
7) The signal is measured.
When the p-p value of the CD traverse waveform (24~) is measured, the PI level
l
of the DVD is measured at the same time.
l
differentiate between CD/DVD-SL/DVD-DL.
CD/DVD differentiation: TE is generated as a clear traverse waveform,
l
waveform.
DVD
Figure. 3-20. Traverse waveform
Figure. 3-21. PI waveform
at one time