Picture Quality Control Circuit - Panasonic UF-585 Service Manual

6.2.5

Picture Quality Control Circuit

This circuit consists of a recording picture control standard cell IC2 [DZAC000157 or "PEGASUS"] , an interpolation table ROM
(IC3), line memory for interpolating (SRAM) and its peripheral circuitry.
The recording picture control standard cell (IC2) inputs the parallel data from the system bus, conducts picture quality correction
(smoothing), reduction, synchronization control, etc., then sends this data to the printer. These functions are as follows:
Picture quality correction circuit (smoothing)
Compares the picture element with 15 surrounding picture elements, determines the interpolation data from the interpolation
data ROM, and smooths out diagonal lines, etc., on the recorded picture.
Image range isolation circuit
Identifies the halftone picture range and controls smoothing to eliminate blotching of the recording picture which has undergone
error diffusion or other processing.
Reduction circuit
This circuit is used to process the received data so that it fits on the recording paper, according to the Fax Parameter settings.
Synchronization control circuit
This circuit is used to synchronize the output recorded data with the horizontal synchronizing output signal from the printer f or
each line. Within a line, it is synchronized with the dot clock signal. The dot clock signal is provided by dividing the crystal
oscillator frequency from the Extend Generator Circuit (16 MHz) by 5.
Smoothing
Data
ROM
[IC3]
Line
Data
Memory
16 MHz
Crystal
Oscillator
Address Address Address
Smoothing
Process
Data
Circuit
RAM
I/F
Address Timing
Generator
Circuit
Recording Picture Process Circuit
Scanning
Synchronization
Circuit
Horizontal
Sync
Circuit
Register
Block Diagram
199
Scanning LSI
[IC17 (IC7)]
Laser Printer I/F
Control Signal Control Signal Control Signal
System
Bus
CPU Bus
Data Bus
I/F
Address
(IC2)
UF-595 (UF-585)