Ricoh Aficio SP C231, Service Manual, Page: 50 / 247

IMAGE-PROCESSING
2-10
C231 SM
2.2 IMAGE-PROCESSING
2.2.1 OVERVIEW
This model uses a contact image sensor (CIS) instead of a CCD. It removes the
necessity for the complicated adjustments that are needed for a CCD scanner.
There are three main chips on the main processing unit (MPU) as shown. The
halftone processor chip enables the use of Letter/Photo mode in addition to Letter
and Photo modes. In Letter/Photo and Photo modes, error diffusion processing
produces better copy quality halftone images.
The halftone processor also includes the A/D conversion function, as well as the
image processing functions. The thermal head drive function is built into a chip
(GA2) on the MPU.
A/D
Conversion
Data
Compensation
Main
Control
Data
Selection
Thresholding
Error
Diffusion
MTF
Correction
Letter/Photo
Image Area
Detection
Contact Image
Sensor
Power Supply
PCB
Clock
Image
Enlargement/
Reduction
Centering
Main-scan Direction
Image Position
Adjustment
Data
Selection
Overlay
Thermal
Head
Data Selection
Thermal
Head
Drive
Amplification
Main Processing Unit (MPU)
Half Tone Processor
GA1
GA2
C231D509.WMF