Shading Correction - Canon 1130 Service Manual

CHAPTER 4 IMAGE PROCESSING SYSTEM
B. Shading Correction
The output of the CCD will not necessarily be uniform even if the light it receives is from an
original of even density. To make up for any discrepancy, shading correction is performed and the
data (collected while scanning an original) is corrected to generate data representing uniform light
distribution.
Measurements for correction are taken when the power switch is turned on and at the end of
copying operation, thus preparing for the next copying job.
Part 2>Chapter 3>2.1
a. Shading Correction
1. The CCD reads the bar code found under the standard white plate, and determines a
correction target value (Reference 1).
2. The CCD measures the light reflected by the standard white plate, and generates its output.
3. The shading correction circuit compares the measurements taken in 2 against the target
value determined in 1, and saves the difference as the shading correction value.
1. A bar code label is attached to the copier's standard white plate. At the
REF.
2. The color balance of light areas may be adjusted in service mode
3. If the density or color balance of copies of a negative film cannot be
4. Scratches or dirt on the standard white plate will be subject to stronger
4-6
COPYRIGHT © 2002 CANON INC.
Standard
Bar code
white plate
Glass
Figure 4-402
factory, light of a specific intensity is directed to the standard white plate and
measured (B, G, and R values); the result is converted, and printed in the
form of a bar code for shipment.
(ADJUST>COLOR>ADJ).
corrected using a base film, use service mode (PRJ>ADJUST>NEGA).
shading correction, causing vertical white lines on copies. If such is the case,
clean the standard white plate; if the problem is not corrected, try changing
the position of shading correction using service mode (ADJUST>ADJ-
XY>ADJ-S).
CANON CLC1100/1130/1150/1160/1180 REV.2 FEB. 2002 PRINTED IN JAPAN (IMPRIME AU JAPON)
Copyboard glass
Scanning lamp
Lens
CCD