Instruction manual
Marlin Technical ManualV.2.7.0
62
Description of the data path
IBIS5A multiple slope (High Dynamic Range
mode)
The Marlin F-131 sensor has a high dynamic range of about 60 dB. This can be
extended to almost 100 dB by switching to a special mode.
This mode is called dual (in the case of rolling shutter) or multiple slope mode
(in the case of global shutter).
The following diagram, taken from FillFactory's application notes, explains the
functionality.
The colored lines represent the analogue signal on the photo diode which
decreases as a result of exposure. The slope is determined by the amount of light
at each pixel (the more light, the steeper the slope). When the pixels reach the
saturation level, the analogue signal will no longer change despite further light
exposure. As shown in the diagram, without any dual or multiple slope pulse,
pixels P3' and P4' reach saturation before the sample moment of the analogue
values.
When dual slope is enabled, a second reset pulse will be given (blue line) at a
certain time before the end of the integration time.
This dual slope reset pulse resets the analogue signal of the pixels below the
dual slope reset level to this level. After the reset, the analogue signal starts to
decrease with the same slope as before (pink P3 and yellow P4 lines).
Figure 32: Multiple slope (high dynamic range) pixel charge as a function of time