Sbu (Sensor Board Unit) - Ricoh B264 Service Manual

IMAGE PROCESSING

6.5.2 SBU (SENSOR BOARD UNIT)

Processing
The CCD converts the light reflected from the original into an analog signal. The
CCD line has 7200 pixels at a resolution of 600 dpi.
The CCD has two output lines to the analog processing ASIC, one for handling odd
and one for handling even pixels. The analog processing ASIC performs the
following operations on the signals received from the CCD:
Z/C (Zero/Clamp): Adjusts the black level for even pixels to match the odd pixels.
Signal composition: Analog signals for odd and even pixels from the CCD are
merged by a switching device.
Signal amplification: The analog signal is amplified by amplifiers in the AGC
circuit. The maximum gains of the amplifiers are controlled by the CPU on the
BICU board.
After the above processing, the analog signals are converted to 8-bit signals by the
A/D converter. This gives a value for each pixel on a scale of 256 shades of gray.
Then, this data goes to the BICU via the SIB.
B264/B265
SBU
A/D
Converter
Analog
A/D
Converter
ASIC
8 bit Serial Data
GA
6-18
BICU
IPU
B195D910.WMF
SM