Ccd Drive - Canon iR4570 Series Service Manual

Analog image
processing
-gain correction
-offset correction

5.3.6.2 CCD Drive

iR2270 / iR2870 / iR3570 / iR4570 / iR3530
The machine's CCD sensor is a 1-line linear image sensor consisting of 7488 photocells. After completion of
photoelectric conversion in the light-receiving block, the signals are output to the AP circuit in the reader controller
circuit board in parallel for each channel (total eight channels) of the CCD array.
CCD8 CCD7 CCD6
Light-receiving block
F-5-27
5.3.6.3 Gain Correction and Offset Correction of the CCD Output
iR2270 / iR2870 / iR3570 / iR4570 / iR3530
The analog video signal generated by the CCD is corrected so that it will have a specific level (gain correction);
moreover, the output voltage occurring in the absence of incident light is also corrected so that it will have a specific
Contact image sensor CIS)
CCD(1 line)
Analog
image
signal
CCD
drive control
A/D
conversion
CCD/AP circuit
CCD5
L L H H L H L
CCD
control signal
Gain
correction
CPU
data
Digital
image signal
Shading
correction
10
F-5-26
CCD2 CCD1
output
H H H L
Reader controller PCB
EEP-ROM
Target value
SRAM
J502
Digital
image signal
8
Chapter 5
0006-5931
0006-5932
5-23