Canon LBP-860, Руководство по обслуживанию

Страница: 49 / 219

CHAPTER 2
3. laser diode emission control
Laser
diode emission is controlled by VIDEO
signal which is sent from the video
controller and processes the paper size data.
The paper size data is input to the CPU
from the cassette size sensing switches for
cassette feed and by the paper size
command from the video controller for
multi-purpose tray feed.
The CPU transfers the
signal from the video controller to the laser
driver as it is as the signal
The CPU sends data to the gate array
to generate the TOP ERASE
AND BOTTOM ERASE signal and
H O R I Z O N T A L M A S K s i g n a l
according to the paper size data from
and MSK are used by
and not output externally.)
To prevent the laser beam from writing
on the non-image area during the non-
unblinking period, makes the
DATA ENABLE signal
only when the TOPE and MSK signals are
The laser driver switches the laser ON
when the signal is and the
signal is
The gate array generates the
UNBLINKING signal (UBL) according to the
BD INPUT signal sent from the BD
PCB in the laser/scanner unit. sets
the UBL signal lo d u r i n g t h e
unblinking period and sets the FORCIBLE
LASER ON signal The laser driver
switches the laser diode ON when the
signal is
M S K
Notes: 1.
2.
Figure 2-13
Indicates the area where the
laser beam writes on the drum.
The duration of T2 vary
according to paper size. When
using the multi-purpose tray
the printer cannot comprehend
the width of the paper when
p a p e r s i z e h a s n o t b e e n
specified by a paper size
c o m m a n d f r o m t h e v i d e o
c o n t r o l l e r . is therefore
specified as legal size paper
(maximum printable width).
2 - 1 2