Driving The Ccd; Gain Correction And Offset Correction For The Ccd Output; A/D Conversion Of The Ccd Output - Canon Color iR C3480 Service Manual

Chapter 5
(1) Analog Image Processing
(a) drives the CCD
(b) performs gain correction and offset correction for the CCD output
(c) performs A/D conversion for the CCD output
(2) Digital image Processing
(a) performs shading correction
CCD (RGB, 1 line each)
Even-numbered
image processing
- gain correction
- offset correction

5.3.7.2 Driving the CCD

Color iR C3380G / Color iR C2880G / Color iR C3380i / Color iR C3380 / Color iR C2880i / Color iR C2880 / iR C3480 / iR C3480i / iR C3080 / iR C3080i / iR
C2550
The machine's CCD sensor is a linear image sensor that consists of 3 lines (RGB, 1 line each), and it is composed of 7488-pixel photocells. The signals generated
through photo conversion at the light-receiving segment are sent as analog signals according to pixels in the order of G, B, and R.

5.3.7.3 Gain Correction and Offset Correction for the CCD Output

Color iR C3380G / Color iR C2880G / Color iR C3380i / Color iR C3380 / Color iR C2880i / Color iR C2880 / iR C3480 / iR C3480i / iR C3080 / iR C3080i / iR
C2550
The analog video signal from the CCD is subjected to gain correction (in which the rate of amplification is corrected to a specific level) and offset correction (in
which the output voltage in the absence of incident light is also corrected to a specific level).

5.3.7.4 A/D Conversion of the CCD Output

Color iR C3380G / Color iR C2880G / Color iR C3380i / Color iR C3380 / Color iR C2880i / Color iR C2880 / iR C3480 / iR C3480i / iR C3080 / iR C3080i / iR
C2550
5-18
Contact image sensor (CIS)
Odd-numbered
pixel pixel
CCD drive control
Analog
image signal
Even-
numbered
Analog
pixel
A/D
conversion
Odd-
numbered
pixel
CCD/AP circuit
CCD16 CCD15 CCD14
R R R R
G G G G
B B B B
Single analog
shift register
Reader controller PCB
SCD control
signal
Line correction
data
CPU
Digital
image signal
Shading
correction
10
F-5-30
CCD13 CCD2
R R R R R
G G G G G
B B B B B
output
G B R G B R G B R
F-5-31
EEP-ROM
Target
value
SRAM
J203
Digital
image signal
8
CCD1
R R R
G G G
B B B
G B ......
0013-8594
0013-8595
0013-8597