CXD2510Q
(b) Track jump
1, 10, and 2N-track jumps are performed respectively. Always use this when focus, tracking, and sled servo
are on. Note that tracking gain up and braking on ($17) should be sent beforehand because they are not
performed.
• 1-track jump
When $48 ($49 for REV) is received from the CPU, a FWD (REV) 1-track jump is performed in
accordance with Fig. 3-9. Set blind A and brake B with register 5.
• 10-track jump
When $4A ($4B for REV) is received from the CPU, a FWD (REV) 10-track jump is performed in
accordance with Fig. 3-10. The principal difference between the 10-track jump and the 1-track jump is
whether to kick the sled or not. In addition, after kicking the actuator, when 5 tracks have been counted
through CNIN, the brake is applied to the actuator. Then, when the actuator speed is found to have
slowed up enough (determined by the CNIN cycle becoming longer than the overflow C set in register 5),
the tracking and sled servos are turned on.
• 2N-track jump
When $4C ($4D for REV) is received from the CPU, a FWD (REV) 2N-track jump is performed in
accordance with Fig. 3-11. The track jump count "N" is set in register 7. Although N can be set to 216
tracks, note that the setting is actually limited by the actuator. CNIN is used for counting the number of
jumps when N is less than 16, and MIRR is used when N is 16 or higher.
Although the 2N-track jump basically follows the same sequence as the 10-track jump, the one difference
is that after the tracking servo is turned on, the sled continues to move only for "D", set in register 6.
• Fine search
When $44 ($45 for REV) is received from the CPU, a FWD (REV) fine search (N-track jump) is performed
in accordance with Fig. 3-12. The one difference from a 2N-track jump is that a higher precision is
achieved by controlling the traverse speed. The track jump count is set in register 7. N can be set to 216
tracks. After kicking the actuator and sled, the traverse speed is controlled based on the overflow G. Set
kick D and F in register 6 and overflow G in register 5. After N tracks have been counted through CNIN,
the brake is applied to the actuator and sled. This is performed by turning the tracking servo for the
actuator on, and by kicking the sled in the opposite direction. The cancel command $40 is sent from the
CPU when track jump is terminated.
Set overflow G to the speed required to slow up just before the track jump terminates. The speed should
be such that it will come on-track when the tracking servo turns on at the termination of the track jump.
(Set the target track count N-α for the traverse monitor counter which is set in register B, and COMP will
be monitored. When the falling edge of this COMP is detected, overflow G can be reset.)
– 40 –
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