Canon NP-70 Service Manual page 52

3-10
NP -70
Block Actions Occurring
The following are the actions occuring within the machine as it is initially started.
C
START ~
It should be noted that a path of operation is provided in the event COPY ~ is also
desired.
Turning ON the power switch (SW) provides power to components within the copier
to start the process of machine preparation known as "warm-up". The flowchart
shows the most significant components and the condition that they assume at the
instant of power turn-on. For information about the operation of those components
which are ENABLED, refer to the section indicated next to each. In this section
the following points should be noted:
a) Transistor Q43 is OFF at this time because its base bias path (C30) is not yet
functional. Thus, Q44 is ON to allow the exposure lamps to energize quickly
for stabilization of illumination.
b) Capacitor C 13 will charge for 5.0 seconds before turning Q 15 (and, thus, Q 16)
ON. This delay permits the developer liquid to be pumped to the point where
the cleaner blade and drum are in contact so that the toner sticking to the
cleaner blade can be dissolved before the drum is started. This decreases the
friction between the drum and cleaner blade and prevents the drum surface
from being damaged.
c) Motor M2 comes ON immediately to stir the developer liquid in the Developer
Assembly. This stirring is performed to ensure uniform density of the liquid
before copying is performed.
SW
"ON"
Capacitor C16 completes its charging and turns on the illumination lamps (FL2 &
3) so that they will stabilize as soon as possible.
STEP 1 S
At this time, the main motor (M 1), the coronas, and the overall exposure lamp
come ON to condition the CdS material in the drum for copying. Capacitor C30
begins to charge so that Q43 can become functional; this charge time is 12.0 secs.
STEP 2S
Capacitor C30 completes its charging and Q43 is turned ON. As a result, Q44 is
biased OFF and will remain so as long as the copier remains "ON". With Q44 OFF,
the operation of C 16 will henceforth be controlled by voltage through either diode
D16 or D17; the voltage through these diodes occurs only when operation is start-
ed by pressing the COPY button.
If the COPY button is/was pressed, copy operation will begin at 21.7 seconds of
operation (4.0 revolutions completed); however, if the COPY button is unpressed,
C16 will begin its 8.0 second discharge period (containing the first feed interval).
STEP
3S
(both "copy"
& "no-copy")
Second Printing-.tune, 1974
© CANON INC.