Scanlab RTC 5 PC Interface Board, Installation And Operation Manual

Page: 107 / 622

RTC
®
5 PC Interface Board
Rev. 1.9 e
7 Basic Functions for Scan Head and Laser Control
107
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• If the table contains no valid data point, then the
command load_varpolydelay will have no effect
(return value 1 or 13).
• The angle

= 0° means that two successive
vectors are parallel and are marked in the same
direction.
If the table contains no explicit data for

= 0°
(equality is checked to within ±0.01°), then a
data point for

= 0° with the scaling factor
scale (0°) = 0 is added.
• The angle

= 180° means that two successive
vectors are marked in the opposite direction.
If the table contains no explicit data for

= 180°
(equality is checked to within ±0.01°), then a
data point for

= 180° with the largest scaling
factor found in the table for scale (180°) is added.
After initialization of the RTC
®
5 (with
load_program_file ), the internal (default) table for
the variable polygon delay (1–cos(

), see figure 34 on
page 104 ) is used. Alternatively, this can also be
achieved with
Name
= 0 in load_varpolydelay .
7.2.3 Notes on Optimizing the
Delays
The delays have to be set with the commands
set_scanner_delays and set_laser_delays . The
delays have to be appropriate for the defined jump
speed and the marking speed. If the delays are not
optimized, the quality of the scanning results will
under some circumstances be reduced and scanning
time will be extended. The figures on
page 110
through page 112 show the various effects of non-
optimized delays on the letters “RTC“.
Recommended Sequence
The LaserOn delay and the LaserOff delay should be
optimized first, followed by the delays for scanner
control, i.e. the jump delay, the mark delay and the
polygon delay. When optimizing the laser delays, it is
useful to set the jump delay and the mark delay to
long values.
The lengths of the LaserOn delay and the LaserOff
delay have no influence on the total scanning time if
positive values are chosen (also see the following
section).
Automatic Delay Adjustments
All delays can be set for any value within the corre-
sponding permissible range. With predecessor
boards, however, some delays would result in laser
control errors (when laser-on and laser-off overlap).
Therefore, the RTC
®
5 checks each vector’s defined
delays and – if necessary – performs an appropriate
adjustment of the delays for the respective vector:
(1) Adjustment of the LaserOff Delay
With predecessor boards, if the specified LaserOff
delay is shorter than the LaserOn delay
(LOffD < LOnD), then very short mark vectors
could cause the LaserOff delay to finish
before
the LaserOn delay has finished. These boards
would then attempt to switch the laser off before
it had actually been switched on, and then switch
the laser on without later switching it back off
(see
figure 37 on page 108 ).
Note:
• Note that the laser delays must be specified in
units of 0.5 µ s, whereas the scanner delays
(jump delay, mark delay and polygon delay)
must be specified in units of 10
µ s.