Pioneer AVIC-HD3, Service Manual

Page: 295 / 317

6
1
2 3 4
1 2
3 4
CX-3016
F
E
D
C
B
A
2. Focus closing
Next, the pickup lens moves away from the disc to detect the focus closing levels for FE and AS signals. The focus
loop filter operates to close the focus loop (3 through 6 in the above diagram).
3. Verifying focus close completion
The focus close completion is verified by observing the AS and RFENV signal levels (6 and 7 in the above
diagram).
In the test mode, focus search is used to verify the FE, AS and RFENV signal levels and the focus drive voltage.
1.2.2 Tracking close
After a tracking-close command is issued, the following procedures are performed irrespective of DVDs and CDs:
1. Tracking brake
A half cycle of the track-cross (TKC) signal is measured. If the measured cycle falls within the prescribed range,
then a brake pulse signal is output. The direction of the brake pulse depends on the relation in phase between the
OFTR signal and TKC signal (which is obtained by converting the TE signal into a binary signal). When it is
confirmed that the stability in lens operation against the disc has been obtained, the brake pulse output will be
terminated, and the operation will proceed to the track-closing mode. If it is not confirmed, the brake pulse output
will be terminated 10msec. after the brake pulse signal is output, then the operation will automatically proceed to
the track-closing mode.
2. Tracking closing
The tracking drive-hold process is performed with the OFTR signal.
3. Verifying tracking close completion
The success or failure in tracking close depends on the number of tracks that the pickup crosses within the
prescribed period. That is, when the number is the prescribed one or less, the system senses that the tracking
close is completed. The time limit for the tracking close verification process is 20msec. The retry operation will be
carried out with the command from the microcomputer if the verification has not been completed within the time
limit.
1.2.3 Track jump
This system performs track jumps by selecting the following three modes depending on the number of tracks to be
skipped: Interval jump, multi jump and traverse jump.
1. Interval jump
In this mode, a single-track jump is performed repeatedly. This mode is used for fine seek operation when the
pickup has approached the target track or adjacent tracks are targeted.
2. Multi jump
This mode performs the pickup track-count movement by counting both edges of the TKC signal to jump the
target number of tracks.
3. Traverse seek
In this mode, the time is measured with the TKC signal to control the pickup speed. During the movement of the
pickup, its vibration is minimized.
The track-jump mode settings for DVDs and CDs are shown below:
Target number of tracks Track jump mode
1~10 Interval jump
11~100 Multi jump
101~500 Combination of multi jump and interval jump
501~ Traverse seek
The waveform in each of the track-jump modes is shown in the following pages.