8
CX-961
• Track jump
A track jump is automatically performed with a
microcomputer command using the LSI auto
(automatic) sequence function.
This system has one to 99 lens kick modes as the track
jump used at search and the carriage move used in the
jump exceeding 1,000 tracks. The test mode can check
the jump of lens kick modes 1, 32 and 99 and the
carriage move according to the mode selection.
• Lens kick Jump
Lens Kick jump is executed as soon as the LSI receives
the Lens Kick command from the microcomputer. The
direction of jump and the number of tracks are
determined by the command’s parameters. When the
LSI receives the Lens Kick command, the jump is
performed by inputting a kick pulse to the tracking EQ.
The LSI controls lens traveling speed, referencing to the
table held internally. By doing so, the lens travels faster
when there are a good number of tracks to go, while
the lens traveling speed gets slower as the remaining
tracks decrease. After track count has been completed,
tracking close is performed. During jump, an RFRP
signal is watched to perform track count and the
direction of the jump is detected according to the phase
of RFRP or TEZI. Besides, to improve the servo feed at
track jump, the tracking servo gain increase and
hysteresis operation are performed for 50 ms after
tracking close has been completed. The FF/REV
operation in the normal mode is implemented by
continuously performing a single jump. The speed is
about 10 or 20 times the normal mode. (It depends on
destinations).
• Carriage move jump
A carriage move jump is executed by issuing a carriage
move command from the microcomputer. The
direction of the move and the number of tracks are
specified with the command. When the LSI accepts the
carriage move command, the jump is performed by
opening the tracking servo, applying a kick signal to the
carriage equalizer and driving the carriage motor. The
profile of a signal applied in this time is provided with a
time constant at rise time. As the remaining tracks
decrease, voltage is lowered that results in slower
carriage traveling speed.
The servo feed at the end of the jump is improved by
reducing the speed in this manner immediately before
the jump terminates.
Besides, to improve the servo feed at the end of the
jump, the tracking servo gain increase and hysteresis
operation are performed for 60 ms after the jump has
been performed.
EQUALIZER
HYSTERESIS
CLOSE
GAIN UP
NORMAL
TE
RFZC
(LSI INTERNAL SIGNAL
PRODUCED FROM RFRP)
(LSI INTERNAL SIGNAL
PRODUCED FROM TEI)
TEZC
SERVO
OPEN
ON
OFF
50ms
THE HYSTERESIS OPERATION
OF THE1-4 TRACK JUMP IS 2 ms.
50ms
Fig.11:LENS KICK
SD
TE
SERVO
EQUALIZER
HYSTERESIS
OPEN
CLOSE
GAIN UP
NORMAL
ON
OFF
60ms
60ms
Fig.12:CARRIAGE MOVE
