Panasonic UF-890 Service Manual page 235

6.2.5 Picture Quality Control Circuit
This circuit consists of a recording picture control standard cell IC140 (DZZAC000168 or "IPC"), an
interpolation table ROM (IC141) and its peripheral circuitry. The recording picture control standard cell
(IC140) inputs the serial data from the IC110 (DZZAC000167or "PEC"), 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 for 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
(32 MHz : 16 x 15.4, 18.117MHz : 600 dpi) by 5.
18.117MHz
32MHz
Horizontal
XIN
Synchronization
Circuit
XOUT
SYRST
CSLIC
RD
System Register
WR
Bus
A5 1
Interface
D15 0
INTRQ
PSDA
PSCK
PSRQ
ENB0 4
VDOCK
ENB0 4
Print
VDOCK Dot
Data
Convertor
VIDEO
Control
BUNRI
Timing Generator
Circuit
235
HSYNC
VSYNC
VDOCK
Smoothing
ZA16 0
Data
ZD7 0
ROM
VDO
ZD7 0
(DO7 4)
FIFO
I/F
(DI7 5)
DUDAT
(DI4)
FDO3 0 (DO3 4)
FIFO
I/F
FDI3 0 (DI3 4)
FEN
FCK
FRST