- SS-HQ1 Application Notes -
Ver.1.0.0 January 7, 2005
164
is a graph illustrating the correlation between the CCD blemish level, accumulation time
(DETACCT) and threshold level (DETREFL/M). Because exposure time is less than one field in practice, the
CCD blemish level is the Real (1-field) line in the graph. However, blemish detection errors increase at the
100mV/102 gradient. Therefore, the accumulation time (DETACCT) is increased and CCD output is increased
to improve detection precision.
For example, if DETACCT = 32 (20h), output equivalent to AGC30dB can be obtained and detection can be
performed at the 15.6mV/511 gradient without degrading the S/N ratio.
However, please set DETACCT to
become Det_Max_value = ((1000[mV] - black offset [mV]) / 1000[mV]) x1023 < 3FF[h].
Fig 11.2-4 CCD Blemish level/accumulation time and DETREF
Black offset value
3FF[h] (1023)
Det Max value
DETREF
Real (1 field)
DETACCT=4 [field]
DETACCT=8 [field]
DETACCT=16 [field]
CCD Blemish Level = ADin at
BLMDETAGC_0dB
0
66[h] (102)
100mV
DETACCT
=32 [field]
DETACCT=2 [field]
1FF[h] (511)
15.6mV
Safety Area
Detect Area
Det
_
s
ig
n
al L
e
v
e
l
(Z
1 blo
ck)