m62481fp Mitsumi Electronics, Corp., m62481fp Datasheet - Page 89

• Manufacturer Part Number: m62481fp
• Description: Pickup Servo System With Automatic Adjustment
• Manufacturer: Mitsumi Electronics, Corp.

Some pick up units may have a phase turbulence around the ideal adjustment frequency. So the phase diagram may look like
that in figure 2. Those phase turbulence can cause miss adjustment.
It is necessary to overcome this effect by the adjustment software.
E.g.:The adjustment frequency is shifted to a lower or a higher frequncy , which results in a systematic misadjustment.This
systematic misadjustment must then be taken into acount by the adjustment software.
Phase shift circuit for auto adjustment
The adjustment frequency for the auto adjustment is the frequency where the phase shift for the comparator is 90. When
the phase characteristic is smooth around that adjustment frequency (figure 1). The standard circuit for the feed-in of the
adjustment frequency can be used (figure 3).
D-62481-87I
Below figure shows the feed-in circuit in the track servo.
APPLICATION NOTE
Figure 2: Phase Diagram of Pick Up + Servo with phase turbulence
-270
-180
-360
Figure 1: Phase Diagram of Pick Up + Servo
-90
-180
-270
-360
-90
0
0
100Hz
100Hz
Figure 3: Circuit Examples
JP1 Input
Circiut
270k
Example Adjustment frequency
TG SIG
TE Amp.
- input
1KHz
1KHz
is shifted to a lower or higher frequency
M62481FP
TE1 Amp
Adjustment
frequency
2
PICKUP SERVO SYSTEM WITH AUTOMATIC ADJUSTMENT
(
MITSUBISHI
88
ELECTRIC
TE2 Amp.
/ 88 )
Phase turbulences
VREF=1/2Vcc
MITSUBISHI SOUND PROCESSOR LSI
3
TG
TE Amp.
Gain control
Note.
Please correspond to phase
turbulences with software.
10KHz
10KHz
M62481FP