Toshiba D-VR3SU Service Manual page 107

7-3 SERVO (DVP Multi Drive)
1) Pick-Up
Data in the disc is processed from the optical pick-up unit (OPU). OPU includes the Elantec chip (EL6912c)
which is a highly integrated laser diode driver designed to support multi-standard writable optical drives. This
chip also has an IV amplifier with concurrent read and write sampling. The architecture allows reprogramming
of the timers to support different media DVD or CD standards, and different speed.
2) A-Chip
A chip is RF processor. This module performs RF signal processing which includes RFIP, RFIN, AGC, RF equal
izer. This processor is able to detect tracking error, focus error and various signals such as CE, PE, SBAD,
DEFECT, BCA, MIRROR, Wobble, TZC, RC, and RECD.
3) C-Chip
C-Chip is composed of DP1, PRML and WS.
First, the Data processor1 (DP1) performs EFM/EFM+ Demodulation and data is stored in the buffer
memory in data processor2 (DP2). DVD data in this buffer is transferred to CSS/ATAPI through
error-correction code
(ECC), descramble process and error detection code (EDC).
Second, WS performs the following processes.
!Delay compensation using Shift register
@Sample/Hold pulse generation
#I/V Gain Control
$Providing clock for RF chip
%OPC Control signal generation
Lastly, PRML completes the adaptive EQ/VD and Digital PLL.
4) D-Chip
D-Chip consists of Servo DSP, DP2 and 1Mbit memory. Servo DSP is dealing with controlling the servo-mecha
nism in DVD recorder. Servo-DSP has the following features.
!Bulit-in 10Bit ADC(8ch), DAC(3ch) and PWM(7ch)
@Step Motor Control Logic: Macro/Micro Step
#Track Counter: long distance velocity control direct seek
$Shock/Defect detection
%Header (DVD-RAM)/Land Pre-Pit (DVD-R/RW) Detection
^Several Servo Monitor Signal Detection
&RF IC Interface
* Micom Interface
(Digital Servo Control of focus, tracking, sled and seek
)Disc Auto-Detection
1Automatic Adjustment of the offset, balance and gain of Focus and Tracking Signal
2Direct Seek with Velocity Control
3Step Motor Control: Macro Seek
4De-Track and Lens Shift Detection and Compensation
5Center Error Control
6DVD Layer Jump
7Tilt Detect and Compensation
DP2 performs High Speed ECC and CD DA Decoder.
Circuit Operating Descriptions
7-7