Baumer VCXG - Acquisition Modes and Timings; Non-overlapped vs. Overlapped Operation; Continuous Mode (Free Running)

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8.3 Acquisition Modes and Timings
The image acquisition consists of two separate, successively processed components.
Exposing the pixels on the photosensitive surface of the sensor is only the rst part of the
image acquisition. After completion of the rst step, the pixels are read out.
Thereby the exposure time (t
exposure
) can be adjusted by the user, however, the time need-
ed for the readout (t
readout
) is given by the particular sensor and image format.
Baumer cameras can be operated with differtent acquisition modes, the Continuous
Mode (Free Running Mode), the Acquisition Frame Rate Mode, the Single Frame Mode,
the Multi Frame Mode and the Trigger Mode.
The cameras can be operated non-overlapped
*)
or overlapped. Depending on the mode
used, and the combination of exposure and readout time:
Non-overlapped Operation Overlapped Operation
Here the time intervals are long enough
to process exposure and readout succes-
sively.
In this operation the exposure of a frame
(n+1) takes place during the readout of
frame (n).
Exposur
e
Readout
Exposur
e
Readout
8.3.1 Continuous Mode (Free Running Mode)
In the Continuous mode the camera records images permanently and sends them to the
PC. In order to achieve an optimal result (with regard to the adjusted exposure time t
exposure
and image format) the camera is operated overlapped.
In case of exposure times equal to / less than the readout time (t
exposure
≤ t
readout
), the maxi-
mum frame rate is provided for the image format used. For longer exposure times the
frame rate of the camera is reduced.
Exposure
Readout
Exposure-
A
ctive
t
exposure(n)
t
Exposure-
Active(n)
t
ExposureActiveDelay
t
Exposure-
Active(n+1)
t
readout(n+1)
t
readout(n)
t
exposure(n+1)
t
ExposureActive
= t
exposure
*) Non-overlapped means the same as sequential.
Image parameters:
Offset
Gain
Mode
Partial Scan
Timings:
A - exposure time
frame (n) effective
B - image parameters
frame (n) effective
C - exposure time
frame (n+1) effective
D - image parameters
frame (n+1) effective