CX-977
3) Focus/Tracking AGC
This is the control that automatically adjusts servo loop gain of the Focus Servo and Tracking Servo.
The adjustment is performed in the following manner.
(1) The system (microcomputer) injects a disturbance into servo loop.
(2) Then, caused by such injection, error signals (FE and TE) are generated, and the system samples such error signals
through BPF.
(3) Then, inside the LSI, comparison of the difference of phase between the error signal and the disturbance is
performed.
(4) Finally, the system adjusts the gain so that the difference of phase accords to the target value preset by the
microcomputer.
Fig. 19: Loop gain adjustment
4) FE Bias automatic adjustment
The task of this adjustment is to maximize RFI level by optimizing the focus point during Play. The adjustment is
performed by examining RFRP level and phase-difference as of the time when a disturbance to generate focus errors
is injected into focus loop.
Steps of the adjustment are shown below.
(1) A disturbance is injected into focus loop based on the command issued by the microcomputer. (The session is
performed in the Servo LSI.)
(2) In the LSI, level of RFRP signal is detected.
(3) Also in the LSI, the relation between such RFRP signal and the disturbance is examined, and through such
examination the degree and direction of focus misalignment is detected.
(4) Then, the system substitutes the detected-result for the value in the "Bias Adjustment" item (field).
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ACEC
