13
2.8.3 Startup Sequence
The basic flow is shown below.
(1) Closes the tray.
(2) Detects the peak.
(3) Distinguishes the disc.
(4) SGC
(5) Turns on the focus servo.
(6) Starts the spindle rotation.
(7) ATB
(8) Measures the MIRR modulation degree.
(9) Turns on the tracking servo.
(10) Turns on the slider servo.
(11) Turns on the spindle servo.
(12) Focus AGC
(13) Tracking AGC
(14) AFB
(15) Plays AGC (for CDs)
(16) Plays back.
∗
For a 2-layer DVD, steps (7) through (14 ) are repeated for each
layer.
∗
When starting up with [TV/LDP] in Test mode, all the steps (1)
to (16) are performed for a DVD, and steps (1) to (8) are performed
for a CD.
2.8.4 Peak Detection
Overview
This is a new function to measure the size and location of the sine
wave related to focus errors at the beginning. The measurement is
performed in the normal startup process and in Test mode, as well.
If the sine wave is small, the OE IC gain is switched. Only the
judgment for NO DISC is accomplished at this time. The operation
is in effect as for judgment for DISC .
Using the Function in Test Mode
This function is not assigned to any remote control keys. Only an
open/close operation can trigger the function.
2.8.5 Disc Distinction
Overview
This function is almost the same as that with the first-generation
models. The only difference is as follows: If an error occurs in the
startup sequence and playback cannot be started, startup is retried
after forcibly switching the disc distinction from DVD to CD or
vice verse by a backup process. If startup fails again, it is canceled,
and an error is generated. The types of error that triggers the backup
process for disc distinction are discussed in the next section.
Using the Function in Test Mode
This function is not assigned to any remote control keys. Only an
open/close operation can trigger the function.
2.8.6 SGC
Overview
This is a new function to maintain the sine wave related to focus
errors to a certain size so that the sine wave shows 1.8 V for the P-
to-P value.
This operation is performed each time after judging disc presence
and distinction in the normal startup process and in Test mode, as
well. The operation is achieved by switching the FE gain inside the
RF IC (LA9700) by using the voltage at the SGC connector (pin 22)
of the RF IC.
Using the Function in Test Mode
This function is not assigned to any remote control keys. Only an
open/close operation can trigger the function.
2.8.7 Measurement of MIRR Modulation
Degree
Overview
The slice voltage of the RF signal is measured and used in the
calculation to generate the MIRR signal. This operation is made in
synchronization with ATB ON/OFF in normal startup and in Test
mode, as well.
2.8.8 AFB (Auto Focus Bias) Function
Overview
This function supports DVDs as well as CDs. The operation is
executed only once (once for each layer for a 2-layer DVD) after
the focus and tracking AGC at startup. The operation is accomplished
not by centering the focus servo to Vref (2.5 V), but by gradually
changing the center value for the optimum jitter value. Thus,
performance with an improper or dirty disc (by fingerprints, etc.),
or the temperature characteristics (at 0
°
C, 35
°
C, etc.) will be
improved.
OverviewUsing the Function in Test mode
(the Remote Control Keys to be Used are
Indicated in Brackets)
As the function is to be synchronized with AGC, turn on and off
AFB by pressing [TEST] + [7]. The jitter value measurement cannot
be made with AFB ON.
