SMO-F551 Technical Guide and Specifications
35
Sony Corporation 1998
Chapter 5. SYSTEM CONFIGURATION
SMO-F551 consists of mechanical, electrical and optical subsystems. The electrical
subsystem consists of analog and digital circuitry.
The analog circuitry includes the laser diode driver, RF circuit and servo systems for
focusing and tracking. The digital circuitry includes analog and mechanical control
logic, modulator/ demodulator, drive interface logic and SCSI control block.
Optical Head
Erasing, writing and reading are performed with a laser diode and photo detectors
located in the optical head housing. The laser diode driver and RF/servo pre-
amplifiers are built in this optical head as well.
Laser Diode Driver
This circuit drives the laser diode at the proper power level for read, write and erase
process using the Automatic Power Control (APC) circuit.
Data Separation Block
The read-out signal from the photo-detectors is divided into two different band-width
signals for data separation and servo systems. Data separation block consists of
RPML channel and bit-by-bit detection channel. PRML channel is used for mark
edge detection in order to detect the RLL(1,7). For peak data detection, data
separation block can also separate the RLL(2,7) by bit-by-bit method. The PLL
generates phase locked clock in order to separate the data of the each channel
correctly. The demodulator decodes the RLL(1,7) or RLL(2,7) in accordance with
this PLL clock.
Bias Magnet Block
Electrical magnet is used to generate the erasing bias magnetic field with the polarity
opposite to writing bias polarity.
Loading Block
Loading block consists of a loading motor and sensors for both loading and ejecting.