b) Brake circuit
Servo withdrawal will deteriorate during setting and track jump. Thus, the system uses the brake circuit to provide stable withdrawal to servo loop. The brake circuit detects the direction of lens movement, and outputs only drive signal in the opposite direction from the lens movement. Thus, the system delays the speed of the lens movement to stabilize withdrawal of the tracking servo. The system judges sliding direction of track from TEC and MIRR signals, as well as the relationship of their phase.
LENS MOVING FORWARDS (INNER TRACK TO OUTER)
LENS MOVING BACKWARDS
TEC
TZC (TEC "SQUARED UP" ) (INTERNAL SIGNAL )
MIRR
MIRR LATCHED AT TZC EDGES SWITCHING PULSE = EQUALIZER OUTPUT (SWITCHED) DRIVE DIRECTION REVERSE FORWARD Time Note: In the illustration, the phase of equalizer output is shown as the same as with that of TEC.
