Sbu (Sensor Board Unit) - Ricoh B089 Service Manual

2.3.2 SBU (SENSOR BOARD UNIT)

O
Processing IC1
E
Processing IC2
The CCD converts the light reflected from the original into an analog signal. The
CCD line has 7,450 pixels and the resolution is 600 dpi (23.6 lines/mm).
The CCD has two output lines, for odd and even pixels, to the analog processing
IC. The analog processing IC performs the following operations on the signals from
the CCD:
1. Z/C (Zero Clamp):
Adjusts the black level reference for even pixels to match the odd pixels.
2. Signal Amplification:
The analog signal is amplified by operational amplifiers in the AGC circuit.
3. Auto Gain Control
Adjusts the gain curve for the scanned image density.
After the above processing, the analog signals are converted to 8-bit signals by the
A/D converter. This will give a value for each pixel on a scale of 256 grades. Then,
the digitized image data goes to the IPU board.
SM
SBU
Analog
A/D 1
Analog
A/D 2
2-7
IMAGE PROCESSING
IPU
8 bit data
IPU-A
8 bit data
B027D505.WMF
B089/B093