Scanlab RTC 5 PC Interface Board - Page 196

RTC
®
5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
196
innovators for industry
The entire image line can be slightly shifted due to
the lag between the set position and the real position
and due to the masked acceleration phase (see “Line
Shift” in figure 56). This can be compensated by
adjusting the start position of each image line
(backward-extending the image line).
At the end of the image line (at the beginning of the
default pixel), the pixel pulse length and the analog
output value will be set to a default value, each. The
default pixel pulse length value is 0 unless another
value was defined via set_default_pixel or
set_default_pixel_list. The default analog output
value is 0xFFF (=4095) unless another value was
defined via set_port_default or
set_laser_off_default. The “laser active” laser
control signals will then be switched off without a
LaserOff delay during the next 10 µs clock cycle that
follows the default pixel.
No scanner delay will be inserted at the end of a pixel
line because its value depends on the marking speed
indirectly determined by the
HalfPeriod and ( dX , dY ).
If needed, however, you can insert an appropriate
long_delay after the pixel line’s last set_pixel or
set_n_pixel command.
Notes
• The (half) pixel output period
HalfPeriod should
be adjusted to the longest required pulse length
(for
HalfPeriod < PulseLength /2, the pixel pulse
only ends in the next pixel; therefore, the laser is
not switched off between pixels). Also see the
prior comment on the DA converter.
• The (half) pixel output period
HalfPeriod , the
pixel distance (dX,dY) and (thus indirectly) the
marking speed should be optimized for the
dynamics of the scan system.
• The LaserOn delay should be appropriately set to
take account of the scan system’s tracking error.
• In laser mode 4 and laser mode 6, the pixel pulses
are not outputted at the LASER1 port (which
instead outputs freewheeling standby pulses).
Even so, they are internally generated and the
analog voltage level will change synchronously.
• Output synchronization can’t be used together
with pixel mode. You should first deactivate
output synchronization.