Canon CP660 Service Manual page 164

CHAPTER 5 PICK-UP/FEEDING SYSTEM
The printer unit switches over three feeding speeds according to the paper type mode
signal from the printer board*
The feeding speed is switched when paper arrives at the registration paper sensor
(PS1).
Mode
Feeding speed
The printer unit enters transparency mode when the user selects transparencies on
the control panel. To enable the printer unit to identify a transparency, transparency sen-
sors 1 and 2 (PS1801, PS1802; Figure 5-213) are mounted in front of the pick-up roller.
The DC controller PCB monitors the states of the sensors to identify a transparency
(Note).
A Canon-recommended transparency (OHT TH-1) or a transparency for a color copi-
er has a marking on its leading edge. The marking blocks either of the two sensors
(PS1801, PS1802), causing the DC controller PCB to assume that the transparency is of
a type that cannot be used for the printer unit; it then communicates the fact to the print-
er board1 and, at the same time, stops the printer unit (Note 2).
1
* Reader controller PCB (when making prints with the reader unit installed).
Note:
1. Paper is stopped once at the registration roller before re-pickup, and the DC con-
troller PCB checks the two sensors (PS1801, PS1802) during this period.
The sensors are of a feedback type, consisting of a light-emitting section and a
light-receiving section. If a transparency exists between the sections, the light from
the light-emitting section passes through it to reach the light-receiving section,
enabling the DC controller PCB to identify the medium as a transparency, thereby
starting transparency mode.
2. Canon-recommended transparencies (OHT TH-10) are extremely thin, and are
impregnated with oil. The printer unit, on the other hand, uses two fixing heaters,
and the high caloric value can cause such transparencies to jam inside the fixing
assembly.
Likewise, the printer unit rejects transparencies intended for a color copier (identi-
fying them as such in response to the marking on the leading edge by stopping the
ongoing operation).
5-2
COPYRIGHT © 1999 CANON INC.
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1
. Table 5-101 shows the speed used for each paper type.
Normal Thick paper
Normal 1/3 of normal
Table 5-101
CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Transparency
1/4 of normal