Ricoh D009 Service Manual page 567

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.
SBU of CS (Color Scanner) Model
SBU
The VPU (Video Processor Unit) does the following functions:
Black level correction
White level correction
Gradation calibration
ADS control (Background Density)
Creating the SBU test pattern
Operation Summary
The signals from the 3-line CCD, one line for each color (R, G, B) and 2 analog signals per
line (ODD, EVEN), are sampled by the ASIC and converted to digital signals in the 10-bit
A/D converter. This is the first phase of processing the data scanned from the original.
Storing Operation Settings
The controller stores the SBU settings. These values must be restored after the lens block is
replaced:
SP4-008-001 Scanner Sub Scan Mag
Scanner Leading Edge
SP4-010-001
Registration
Scanner Side-to-Side
SP4-011-001
Registration
SBU Test Mode
SM
Sub Scan Magnification Adjustment
Sub Scan Registration Adjustment
Main Scan Registration Adjustment
6-17
Image Processing
D009/D011/D012/D013