AVIIVA® EM1
50
1043D - AVIIVA EM1 –04/11
e2v semiconductors SAS 2011
6.3.10.3
Tap Balance
How to perform a Tap Balance ?
Why and when performing a Tap Balance ?
Each output of the sensor (Tap) has its own analog Chain and behavior. There could have some discrepancies
between these outputs in extreme conditions of Gain or temperature
The Tap balance is already performed in factory for each level of Preamp-Gain. If necessary, the Tap
balance can be performed again by the User on both Offsets and Gains
The Procedure is the following :
Tap Balance by Offsets
¾
Cover the Lens of the camera to get a dark uniform target. This is not recommended to perform an
Offset balance under light conditions.
¾
Launch the Tap Offset Balance
¾
The process takes a few seconds and can be interrupted when you want
Tap Balance by Gains
¾
Provide an uniform light target to the camera : This is recommended to have a global level of around at
least 70% of the saturation, otherwise, with a low light level (< 30% of the Saturation) the Gain has less
effect than the Offset and your balancing won’t be efficient.
¾
Launch the Tap Gain Balance
¾
The process takes a few seconds and can be interrupted when you want
¾
You can save the result in memory (result for both Gains and offsets).
Internal Process
During the calibration process, the Camera calculates averages on some strategic ROIs (around the junction
between taps) and then estimates the slope of the tangents and then the projections on each side of the
junction.
The adjustment between these two neighbor taps is calculated to cancel the difference between the two
projections (right and left).
Right projection
Left projection
Average area
P
ix
el va
lu
e
Average area
distance
Average
area width
