Controlling The Blank Exposure Lamp (Leds); Outline; Controlling The Activation In Reduce Mode; Controlling The Activation In Direct Mode - Canon NP6045 Service Manual

E. Controlling the Blank Exposure Lamp (LEDs)

1. Outline

The blank exposure lamp is a LED array consisting of 134 LEDs.
All 134 LEDs turn ON when the blank exposure lamp ON signal (BLKON) goes '0'
while the drum is rotating to prevent adhesion of unwanted toner on the photosensitive
drum. (This does not apply while an original is exposed or during potential control and
AE measurement.) The six LEDs at the rear and the six LEDs at the front are kept ON
at all times while the drum is rotating.

2. Controlling the Activation in Reduce Mode

When an original is being exposed while making a reduced copy, as many LEDs
(rear) as corresponding to the ratio of reduction are turned ON to black out (white out)
the non-image area.
The LEDs at the front are also turned ON to suit the copy paper size.

3. Controlling the Activation in Direct Mode

When an original is exposed in Direct mode, as many LEDs (both rear and front) as
corresponding to the copy paper size are turned ON to black out (white out) the non-
image area.
If a non-default ratio is selected or when making copies using sheets of a default size
in Direct mode, a non-image width is created (Table 4-105) at the rear and the front
(standard frame erasing).
The non-image width may be set to 0 mm in service mode.

4. Controlling the Activation in Sheet Frame Erasing Mode

In sheet frame erasing mode, LEDs are turned ON so that toner will not deposit along
the sides of the copy (about 7 mm wide; the width will not vary in relation to the selected
reproduction ratio).
Reference:
In multifeeder mode, copy paper size may be set or left "free." If you have set a size,
frame erasing will be executed according to that size; if free is valid, frame erasing
is controlled based on the maximum size (297
COPYRIGHT © 1997 CANON INC.
2.75mm
Feeding direction
Figure 4-116
CANON NP6045 REV. 1 MAR. 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
432 mm).
7 mm (approx.)
7 mm
(approx.)
7 mm
(approx.)
4-17