Baumer USB3 Vision, User Manual

Page: 16 / 60

16
8.3
Acquisition Modes and Timings
Image acquisition consists of two separate, successively processed components.
Exposing the pixels on the photosensitive surface of the sensor is only the first part of the
image acquisition process. Once the first step is completed, the pixels are read out.
The exposure time (t
exposure
) can be adjusted by the user, however, the time needed for the
readout (t
readout
) is determined by the particular sensor and image format.
Baumer cameras can be operated in three different modes, Free Running Mode, Fixed-
Frame-Rate Mode and Trigger Mode.
The cameras can be operated non-overlapped
1)
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 the exposure and readout suc-
cessively.
In this operation mode, the exposure of a
frame (n+1) occurs during the readout of
frame (n).
Exposure
Readout
Exposure
Readout
8.3.1 Free Running Mode
In the "Free Running" mode, the camera records images permanently and transfers them
to the PC. To achieve the best results (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
Flash
t
exposure(n)
t
flash(n)
t
flashdelay
t
flash(n+1)
t
readout(n+1)
t
readout(n)
t
exposure(n+1)
t
flash
= t
exposure
1)Non-overlapped means 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