AT&T 3B2/300 Technical Reference Manual page 553

FUNCTIONAL D E S C R I P T I O N - - - - - - - - - - - - - - - - - - - - - - - - - -
r-------------------------------------,
DRIVE MECHANISM
CONTROL: :
SPINDLE
MOTOR
LOAD
MOTOR
MAGNET
MOTOR
DATA
SEPARATOR
SLIDE
MOTOR
SPINDLE SERVO
TRACK SERVO
FOCUS SERVO
SLIDE SERVO
o Micro-
processor
oRAM
oROM
o Data
Coding
LASER
DRIVE
I
L-------------------------------------~
r---------------,
I
DISK CONTROLLER
I
I
CIRCUIT MODULES:
o Microprocessor
o Buffer Memory Manager
o Buffer Memory
o SCSI Controller
o Drive Interface Controller
o Error Correction Encoder
o Bus Control Logic
HOST
SYSTEM
Figure 3-95: SCSI Rewritable Optical Disk Drive - Functional Block Diagram
Optical Disk Drive
Disk motion is controlled by the drive mechanism circuitry. The motor speed is controlled by the
spindle servo mechanism which keeps the spindle motor at a constant 2400 rpm.
Read/write head positioning is done by a slide motor and servo system controlled by the data
separator in response to the interface signals. These signals are converted into discrete mechanical
movements which move the motors the proper amount for the required head position.
The laser drive controls the power to the laser diode. A low power beam is used for reading while
a powerful heating beam is required for writing and erasing.
3-300 TECHNICAL REFERENCE MANUAL