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Spyder3 SG-34 GigE Vision Color Manual
03-032-20124-00
Teledyne DALSA
Appendix A: Clear Dark Current
Setting the Readout Mode
Refer to the Clearing Dark Cu rrent section for m ore inform ation on this featu re.
Use the
Readout Mode
featu re (from the
Sensor
Controls
set) to clear ou t d ark cu rrent charge in the
vertical transfer gates im m ed iately before the sensor is read ou t .
The available read ou t m od es are
Auto
,
D ark Current
, and
Immediate Readout
.
Auto
: Clears d ark cu rrent below ~ 45% of the m axim u m line rate. (Defau lt m od e.)
D ark Current Clear
:
Dark cu rrent clear. Alw ays clears d ark. Red u ces the m axim u m line rate.
Immediate Readout:
Im m ed iate read ou t. Does not clear d ark cu rrent.
N otes:
The vertical transfer gates collect d ark cu rrent d u ring the line p eriod . This collected cu rrent is ad d ed
to the p ixel charge. This ad d itional ch arge is esp ecially noticeable at slow er line rates.
This valu e is saved w ith the cam era settings.
If the u ser is u sing internally p rogram m able line rate a nd exp osu re tim e, or
internally programmable
line rate and maximum exposure time,
and
immediate read out mode,
w ith Acqu isition LineRate
Abs at 45% of the m axim u m , and then Read ou tMod e 1 is selected , the follow ing w arning w ill be
d isp layed , bu t the Acqu isitionLineRateAbs valu e w ill not be ch anged : Warning 09: Internal line rate
inconsistent w ith read ou t tim e> The effect in both internal and ex ternal line rate m od es is that an
EXSYN C is skip p ed and , therefore, the ou tp u t w ill be at least tw ice as bright.
Gate Dark Current Clear
Im age sensors accu m u late d ark cu rrent w hile they w ait for a trigger signal. If the read ou t is not triggered
in a reason able am ou nt of tim e, then this d ark cu rrent accu m u lation m ay increase to an excessive
am ou nt. The resu lt of this hap p ening w ill be that the first row , and p ossibly ad d itional row s (lines), of the
im age w ill be corru p t.
The sensor u sed in the Sp yd er3 GEV cam era contains tw o sou rces of d ark cu rrent that w ill accu m u late
w ith tim e: 1) in the p hoto sensitive area, and 2) in the gates u sed to clock -ou t the charge.
The gate d ark cu rrent can accou nt for ap p roxim ately 20% of the total d ark cu rrent p resent. While th e
exp osu re control has d irect control over the am ou nt of d ark cu rrent in the p hoto sensitive area, it has no
control over the ch arge accu m u lated in the gates. Even w ith exp osu re control on, at low line rates, this
gate ch arge can cau se the cam era to satu ra te.
Using the
Readout Mode
com m and , the cam era u ser can control the cam era's behavior in ord er to
m inim ize the d ark cu rrent artifact.
The m od es of op eration selected by the Read ou t Mod e com m and are: Au to, On, or Off.
