Auto Image Density (Ads) - Ricoh A217 Service Manual

EX-IPU

3.1.3 AUTO IMAGE DENSITY (ADS)

f r o m S B U
E V E N
Analog Process IC 1
f r o m S B U
O D D
Analog Process IC 2
This function is the same as in the A133 machine. However, in this machine, the
CPU detects the peak white level only for even pixels using the P/H (Peak Hold)
circuit [A]. This data will be used for the odd pixels.
[A]
Z/C
Multi-
plexer
Z/C
Z/C
Multi-
plexer
Z/C
AGC Z/C
P/H SEL
SEL
AGC Z/C
14
14 August 1997
D/A
Vin
A/D
8
Vref
GA1
(GARD1S)
Vref
A/D
8
Vin
from D/A
Converter
CPU
NVRAM
A217D506.vsd