Image Processing Pcb; Overview - Ricoh VT3500 Service Manual

9.3 IMAGE PROCESSING PCB

9.3.1 Overview

CCD
[Line Mode]
CN402
6-bit
A/D MTF
Correction
Conversion
PCB 6-bit
[Photo Mode]
PSU
CN401
CN404
Main PCB
I/O
Expander
Command
Image Processing PCB
The upper 6 bits of the 8 bits from the A/D conversion PCB are used by this
board. (The other 2 bits are not needed and are discarded.) The digital data
are inverted to match with the circuit of the image processing PCB.
Therefore, the white peak level becomes 0, and the black peak level
becomes 63.
In the line mode, the 6-bit image data are compensated by the MTF
correction. Then if necessary, they are discarded or repositioned by the
magnification and image shift processor. Next the 6-bit image data which
gives 64 graduation steps (64 level grayscale) are converted to single-bit
image data (white or black) by the binary processor. In this step, the image
density is determined according to the level selected by the Image Density
key (Lighter, Normal, Darker 1, or Darker 2). The single-bit image data are
modified in the slim gate if the sharpen image mode is selected by the Image
Mode key.
6-bit
Magnification
6-bit
&
Image Shift 6-bit
Processor
Command
Memory 1
Make-up
Circuit
Memory 2
Commands
Memory 3
Memory 4
Command
Thermal Head Pattern
Energy Pulse Generator
Generator
2-105
Binary
Processor
Slim
Command
Gate
8-bit
Photo Data
Half-tone
Compensation
Processor
Processor
Command
Area 1
Area 2
Area
Area 3
Selector
Area 4
Out of Area
1 December 1993
1-bit
1 bit
1 bit
Selection
Circuit
CN403
Thermal Head
Drive PCB