Overview of Electronic Rolling Shutter (ERS) Exposures
Referring to the following graphic:
Each sensor line is exposed for the programmed time integration period.
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Exposures start with Line 1. The sensor design uses a shared line readout circuit. Due to this
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simplified circuitry, only a single line of pixel data can be readout at any given time. Therefore
the line 2 exposure (integration period) is delayed by the required readout time of line 1.
This delayed line exposure is repeated from the sensor's first line to its last sensor line.
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This sequence allows the common readout circuit to read the data from each row. This results
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in an exposure start time delay between the first to last row - thus the name rolling shutter.
To avoid motion artifacts the user needs to freeze motion using flash lighting of suitable length
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in a dark environment. The flash is triggered at the start of the last line's exposure and stops at
the end of the first line's exposure. The flash must maintain a constant light output during this
period.
To control the flash device, use the Genie Nano output signal with these feature selections:
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outputLineSource=PulseOnStartofExposure, outputLinePulseDelay=flashZoneDelay (delay to
the start of the last line exposure), outputLinePulseDuration=flashZoneDuration (optimal
flash zone time as shown in the graphic below).
The two new features mentioned, flashZoneDelay and flashZoneDuration, automatically
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provide the optimal flash zone time values no matter the exposure duration and any vertical
cropping/offset settings. The user is free to use any delay or duration as required.
The dark environment illumination ensures minimal exposure (and thus motion artifacts) during
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the sensor lines integration time occurring before and after the flash period.
Nano Series GigE Vision Camera
Genie Nano Series Overview • 43