Canon iR2030, Руководство по обслуживанию

Страница: 163 / 418

Chapter 4
4-17
The CMOS sensor outputs are necessary even for the following reasons even when the density of the original is uniform:
(1) Variation in sensitivity among CMOS sensor pixels
(2) Variation in light intensity of rod lens array
The machine performs shading correction to even out the CMOS sensor output.
There are two types of shading correction: shading adjustment performed in the Service mode and shading correction performed for each job.
4.3.6.6 Shading Adjustment
0017-2641
iR2022i / iR2025 / iR2030 / iR2018 / iR2022 / iR2018i
The machine measures the density of the standard white plate, and stores the measured density data. It then processes the stored data to use it as the target value for
shading correction.
4.3.6.7 Shading Correction
0017-2642
iR2022i / iR2025 / iR2030 / iR2018 / iR2022 / iR2018i
The machine performs shading correction for each scan. It measures the density of the standard white plate, and compares the measured value with the target value
stored in the shading correction circuit to use the difference between the two as the shading correction value. The machine uses this shading correction value to
correct the variation among CMOS sensor pixels when scanning the original, thus evening out the image density level.
F-4-32
CMOS
sensor
output
Original density
Standard white plate
Characteristics
before correction
Target
value
Measurement
value
Characteristics
after correction
White