RTC
®
5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
194
Notes
• It is recommended that some experiments be
performed to determine an appropriate
gradation curve for producing smooth greyscales.
The resulting pixel “colors“ (greyscale values)
strongly depend on the employed material and
the laser.
• For an active pixel output mode:
– The LaserOn signal remains continuously
switched on.
–In CO
2
mode, the previously set period and
pulse length values are overwritten and the
pixel pulses are outputted at the LASER1 port as
well as (phase shifted) at the LASER2 port.
– In YAG mode, only the previously defined val-
ues for the Q-Switch delay and/or the duration
of the FirstPulseKiller signal are considered (see
"Timing", page 194); the set period and pulse
length values will be overwritten; the pixel
pulses are outputted at the LASER1 port and
the FirstPulseKiller signal at the LASER2 port.
– In laser mode 4 and laser mode 6, the set free-
wheeling standby pulses (i.e. no pixel pulses)
are, as before, outputted at the LASER1 port
and in laser mode 4 the FirstPulseKiller signal at
the LASER1 port.
– No softstarts (see page 135) are performed.
– Sky Writing (see page 113) is not possible.
• If pixel output mode is deactivated (e.g. even
during a horizontal retrace jump between the
processing of two image lines), then standby
pulses (if previously activated) will be outputted.
• The period and pulse length settings for normal
marking must again be newly defined after the
pixel output mode.
8.8.4 Timing
Figure 56 shows the pixel output timing diagram for
an image line with 3 pixels.
The movement of the galvanometer scanners is
started with the first set_pixel or set_n_pixel
command. The image line is traversed just like a
normal mark command (the motion is microvec-
torized). After an initial acceleration phase, the
scanners will move with an approximately constant
velocity – according to the specified half pixel output
period
HalfPeriod
and the pixel distance (
dX
,
dY
) –
along the entire image line.
At the end of the image line (before the last non-
set_pixel/set_n_pixel command that follows a
set_pixel/set_n_pixel command, thus ending the
pixel output mode) a default pixel will be outputted.
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