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Technology > Controls (Reader)
Technology > Controls (Reader)
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Image Processing
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Overview
The functions of image processing system’s PCB are described below.
- Main controller PCB 2
CCD drive, analog image process, A/D conversion, shading
correction (executed per each job), shading adjustment (executed at
power-on)
- CCD PCB
Analog image process, A/D conversion
The machine uses the main controller PCB to process images for every single image line.
Specific functions are as follows.
a. Main controller PCB 2
- Shading correction
b. CCD PCB (inside CCD unit)
- CCD drive
- CCD output gain correction, offset correction
CCD(4lines )
Analog image
signal
Analog image
process
- gain correction
- offset
correction
A/D
conversion
CCD drive
control
CCD/AP PCB
CCD
control
signal
Gain
correction
data
Digital
image
signal
Main controller PCB 2
CCD PCB
Digital image
signal
EEP-ROM
SRAM
CPU
Shading
correction/
adjustment
ASIC
EEP-ROM
F-2-21
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CCD Drive
The machine's CCD sensor is a 4-line linear image sensor consisting of 7500 pixels. After
completion of photoelectric conversion in the light-receiving block, the signals are output to
the analog front end PCB unit on CCD PCB in parallel for each channel (R, G, B, B/W) of the
CCD array.
………
Light-receiving block
H
L L
H
H L
H
L H
H L
Output
Red(R)line
Green(G)line
Blue(B)line
Black & white(B/W)line
Expanse
●
Gain Correction and Offset Correction of CCD Output
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 level (offset correction).
●
A/D Conversion of CCD Output
The corrected analog video signal is converted into a digital signal that is suited to the voltage
level of individual pixels by the A/D converter.
F-2-22
