Ricoh LD013, Service Manual

Page: 207 / 513

IMAGE PROCESSING
B039/B040/B043 6-14 SM
6.5.2 SBU (SENSOR BOARD UNIT)
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
circuit. The analog processing circuit 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.
After the above processing, the analog signals are converted to 6-bit signals by the
A/D converter. Each pixel will be assigned a value on a scale of 64 grades. Then,
the digitized image data goes to the BiCU board.
S B U
I P U
BiCU
A n a l o g
Processing 1
A n a l o g
Processing 2
E
O
Analog Processing
Circuit
Digital Processing IC
Digital
Processing 1
CCD
A/D 1
A/D 2
Digital
Processing 2
6 bit data
6 bit data
V C U
B039D004.WMF