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– 42 –
The sled error signal is passed through the digital filter in IC506 (DSP), and output
from the DSP as the SOUT ($¡P) signal from the D/A converter.
The SOUT signal is input to DVI (!™P) of the sled drive IC (IC302:LA6527N).
The sled drive IC incorporates a speed (motor rotation speed) feed back control using
the Hall element.
There are two speed detection Hall elements (HA, HB). The detection output is obtained
from the sled motor board (FG-43 board) as the differential output of (HA+, HA–)
(HB+, HB–).
The sled drive IC detects the inclination of the Hall element output waveform during
sled motor rotation (differential value near the zero cross) to form the speed feedback.
In the sled drive IC, after the sled error signal is converted to the sled motor rotation
speed signal, the voltage and current are amplified, and the sled (d.c.) motor is driven
by the output signal (SLDMT+ 2P, SLDMT– 5P).
(2) Sled forced operation control
When driving the sled motor in operations other than playback, in other words during
direct search, the sled speed target signal is input from IC506 (DSP:CXD8730R) #•P
SDCNT to the sled motor driver IC302 (LA6527N) 8P. The data to IC506 (Servo
DSP) is sent from the IC805 SH microcomputer.
The IC506 SLOFS &¢P is the offset adjustment signal of IC302. It is used to adjust the
voltage supplied between the motor terminals to 0 when the sled motor is stopping.
– 43 –
3-2-3.
Spindle Control
This section describes the flow of control signals in the spindle servo during DVD playback.
The CLV control signal is generated from the RF signal obtained from the optical pickup in
IC806 (CXD1865) to generate the two servo error signals-disc CLV speed error (MDSO $•
P) and CLV phase error (MDPO $¶P).
These two error signals is added by IC301 (NJM3404) and output from 7P.
The spindle error output signal SPERR of the 7P of IC301 is input to the spindle drive IC
(IC303:LB1896).
The IC303 is a 3-phase brushless motor drive IC, and it contains a spindle error signal
amplifying circuit, gain switching circuit, and motor forced acceleration and deceleration
control circuit.
Gain switching is done with the SPGC1 signal (!¡P).
Disc size (CD/DVD)
SPGC1 level
12 cm
H
8 cm
L
At the start and stop of disc playing, the forced acceleration and deceleration control is
executed.
Control mode
Input signals
SPCTRL0 (9P)
SPCTRL1 (8P)
Acceleration
H
L
Deceleration
H
H
No control
L
H
Figure 3-11.
DVD spindle control
CLV
control
LC LPF
43
2
1
5
6
7
13
8
9
23
22
19
11
47
SPCTRL 1
SPCTRL 0
From
IC804
LGA CXD8728
Matrix
Gain switching
To spindle
motor
motor
+
–
–
U OUT
V OUT
MODE
Select
H : 12cm
L : 8cm
L : 8cm
W OUT
MIX
LPF
MDSO
ARP
MB-78 board
IC806
CXD1865
IC301
NJM3404
SPEER
IC303
LB1896
SPGCI
MDPO
– 44 –
3-2-4. Tilt Control
Figure. 3-12. Tilt control
(1) Tilt servo by tilt sensor
Tilt control using the tilt sensor of the optical pickup is performed at the start of DVD
playback and CD playback.
The tilt sensor output signal of the optical pickup (TK-47 board CN001, $¡P SKEW IN
(TIA), $™P SKEW OUT (TIB)) is input to tilt amplifier (@º, @¡P) of IC006 (SS13P3720).
After integration and amplification, it is output as the tilt error signal (TIERR @§P).
The servo on/off of the tilt error signal (TIERR) is controlled by the transistor SWQ452
of the MB-78 board.
When the tilt error signal (TIE) level drops within the specified value VCI (+2.5V) ±50
mV, the window comparator output TILTIN (1P or 7P) signal of IC455 (comparator
µPC393) becomes the H level, and switch Q452 is controlled to switch to the @¡P
voltage level VC (+2.5V) of IC361.
As a result, the tilt servo goes OFF to form a dead band.
The TIERR signal during ON is input to the tilt drive IC361 (BA5912AFP).
In IC361, voltage amplification, voltage conversion, and current amplification is carried
out, and the tilt motor (DC brush motor) is BTL-driven by the output signal (TIMT+6P,
TIMT- 5P) of IC361.
20
26
21
57
19
23
3
6
21
22
1
7
73
21
6
5
10
12
10
11
4
26
16
18
17
24
2
12
TIA
TILT
AMP
IC006 SSI33P3720
TK-47 board
MB-78 board
CN005
CN452
TIB
SW
Q452
2SD2114
IC361
BA5912
TILT
DRIVER
TIMT+
TIMT–
To tilt motor
TIOFS
TIE
TIERR
RF
SH/LGA
IC805 HD6437034
IC804 CXD8728
IC506 CXD8730
DSP
H when TIE is within VC1
(+2.5V)
±
50 mV
IC455
µ
PC393
ARP
IC806 CDX8730R
Offset
data
Jitter data
Offset voltage
– 45 –
(2) Tilt offset adjustment minimizing jitter
To optimize RF during DVD playback (excluding search), the jitter (JITTER:time-axis
fluctuation of the RF signal) is measured, offset is added to the tilt servo loop, and the
jitter is minimized.
As jitter is adjusted at shipment, normally this adjustment is not required during playback.
However if the jitter deviates with time, the adjustment value may not be optimum
according to the disc. In such cases, the jitter is measured prior to playback, and if it is
deviated from the specified value, adjustments are started automatically.
The jitter value is measured by IC806 (CXD1865R) and the measured data is sent to
the system controller IC805 (HD6437034) to determine the offset amount. The offset is
voltage-generated by the PWM output of IC506 (DSP), and input to SSI33P3720 !ªP
as the offset voltage (TIOFS).
By performing the above three types of IC control, the jitter is adjusted to optimum.
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