Canon imagePRESS C1 Service Manual - page 293
Chapter 5
5-14
F-5-31
The following shows the functions of the PCBs associated with the image processing system:
CCD/AP PCB: CCD drive, analog image processing, A/D conversion
reader controller PCB: shading correction
The machine performs image processing for every RGB line using the reader controller PCB, and the major functions involved are as follows:
(1) Analog Image processing
(a) CCD drive
(b) CCD output gain correction, offset correction
(c) CCD output A/D conversion
F-5-32
(2) Digital Image Processing
F-5-33
5.3.6.2 CCD Drive
0012-9685
imagePRESS C1 / Color Image Reader-H1 / imagePRESS C1+ (Printer) / imagePRESS C1+
The machine's CCD is a linear image sensor consisting of 3 lines (R, G, B, 1 line each), each line composed of 7350 photo cells. The signal that has been put through
photo-conversion in the light-receiving segment is divided into 2 analog signals of 2 channels for output: even-numbered pixels (EVEN) and odd-numbered pixels
(ODD).
F-5-34
CCD/AP PCB
Reader controller
PCB
CCD
A/D
conversion
Shading processing
Analog image
processing
Analog image processing block
Controller
block
Digital image processing block
CCD (1 line each for R, G, and B)
Analog image
signal
Analog image
processing
- gain correction
- offset correction
A/D
conversion
CCD drive
control
A12V
A5V
J101
J204
J204
J102
J205
CCD control
signal
Gain correction
data
Digital image
signal
Reader
controller
PCB
Odd-numbered
pixel
Odd-numbered
pixel
Even-numbed
pixel
CCD/AP PCB
10
Even-numbered
pixel
Gain correction
data
EEP-ROM
SRAM
CPU
Shading correction
Digital image
signal
CCD/AP
PCB
Reader controller PCB
10
Digital image
signal
8
Target
value
J101
J102
J204
J205
J203
Shift register
Light-receiving segment
(photodiode)
Shift register
Output buffer
Output buffer
Gate
Gate
1
2
3
4
5
6
Odd-numbered pixel data
Even-numbered pixel data