Image Scanning - Ricoh IS450S Service Manual

22 December 1998

2.5.3 IMAGE SCANNING

Analog
Processing
Circuit
Analog
Processing
Circuit
L C
Analog
Processing
E C
Circuit
D D
Analog
Processing
Circuit
Analog
Processing
Circuit
C I S
S h a d i n g Magnification/
correction Mirror Process
As explained on the previous page, the CIS unit contains five CCDs. The analog
signal from each CCD goes to an analog processing IC. The function of the analog
processing circuit is the same as for the SBU. After this, the analog signal is
converted to a digital signal by the A/D converter. Then, the data goes to the
shading circuit for correction. After shading, the data is divided to two signals: Odd
and Even. Then, these go to the IPU on the RCU board.
The RCU board contains the IPU and memory controller ICs for image processing.
The image processing in the IPU is the same as for the IPU in the SCU except for
the shading correction.
After image processing, the data goes to the PC through the SCSI controller on the
SCU.
A D
A D
O d d
Shading
8
A D
Correction
E v e n
8
A D
A D
C I S
γ correction
Filtering
REVERSE SIDE SCANNING
R C U
M e m o r y
IPU
Controller
8
R C U
I P U
Dither/
Error Diffusion
2-23
S C U
S C S I S C S I
8
G411D504.WMF
M e m o r y
Controller
White/black
Binary Process
conversion
G411D526.WMF