Pioneer YPM-2306ZF Посібник з експлуатації - Сторінка 34

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YPM-2306ZF

2. SERVO SECTION (UPD63711GC :

IC201)

The servo section controls the operations such as error

signal equalizing, in focus, track jump and carriage

move. The DSP is the signal processing section used

for data decoding, error correction and interpolation

processing, among others.

This circuit implements analog to digital conversion of

the FE and TE signals generated on the pre-amplifier,

then outputs them through the servo block as the drive

signal used on the focus, tracking and carriage system.

The EFM signal is decoded on the signal processing

section and finally output via the D/A converter as the

audio signal. The decoding process also generates the

spindle servo error signals which is fed to the spindle

servo block to generate the spindle drive signal.

The focus, tracking, carriage and spindle drive signals

are then amplified on the driver IC BA5985FM (IC301)

and fed to respective actuators and motors.

1) Focus Servo System

The focus servo main equalizer is consisted of the digi-

tal equalizer. Fig.10 shows the focus servo block dia-

gram.

When implementing the focus close on the focus servo

system, the lens must be brought within the in-focus

range. Therefore, the lens is moved up and down

according to the triangular focus search voltage to find

the focus point. During this time, the spindle motor is

kicked and kept rotating as a set speed.

The servo LSI monitors the FE and RFOK signals and

automatically carries out the focus close at an appropri-

ate point.

The focus closing is carried out when the following

three conditions are met :

1 The lens approaches the disc from its current posi-

tion.

2 RFOK = "H"

3 The FZC signal is latched at high after it has once

crossed the threshold set on the FZD register (Edge

of the FZD).

As the result, the FE ( = REFO) is forced to low.

IC201 UPD63711GC

A+C

DIG.

A/D

B+D

AMP

CONTROL

FOCUS SEARCH

TRIANGULAR

WAVE GENERATOR

Fig.10 : FOCUS SERVO BLOCK DIAGRAM

IC301

BA5985FM

LENS

FOP

DAC

FOM