Panasonic UF-890 Service Manual page 233

0V
CCD Output
VOUT1
Shading Correction Circuit
The Shading Correction Circuit, included in IC160, is provided to correct for reduction in LED lamp
intensity around the optical lens and LED lamp intensity distortion due to shading of each bit. This circuit
scans the reference white on the transmitting document plate immediately before the document reaches
the scanning position and writes a compensation value according to the distortion of the waveform, at
the time, into the S-RAM (IC170, IC171, IC172).When the actual picture signal is input, the circuit
corrects the picture signal shading, according to this compensation value. This shading is carried out for
each page during transmission or copy.
Offset Control Circuit
The Offset Control Circuit consists of IC161, IC160 and IC118, and controls the black level of the CCD
output to be at 0V by using the IC118.
Picture Signal Binary Coding Correction Circuit
The Picture Signal Binary Coding Correction Circuit is included in IC160. It is used to obtain a binary
coding signal which is a corrected picture and error diffused signal of a false halftone signal, which is
detected from a shaded picture signal.
IC180
AGN
3.0V
0V
ABC Circuit Output
32
IC180
36
IC112
+5V
R673
C650
R674
233
IC160
M86075
19
41
39 Control
Circuit
40