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When viewing high-speed motion, the MV40 works best if the lines are read out at the
maximum possible rate while additional time for exposure or frame period is inserted
between frames. This maximizes the overlap in the line exposure times. Unfortunately in
the non-memory readout modes with reduced output rates just the opposite must be done.
Long interline delays in these modes causes excessive temporal distortion in the moving
image. This can appear as stretching or shrinking of vertically moving objects or
trapezoidal distortion of horizontally moving objects.
T
RIGGER
M
ODES
There are four basic trigger modes:
Free-running mode ignores trigger inputs and reads out the sensor continuously at a
programmed frame rate with programmed exposure timing.
Multi-frame edge-triggered mode activates a programmed number of exposures after a
programmed delay at a programmed frame rate with programmed exposure timing.
Single edge-triggered mode activates a programmed exposure after a programmed delay.
External exposure mode exposes during the active trigger period.
Free-running mode allows continuous readout at rates ranging from about one frame per
minute to the maximum capability of the sensor. Exposure can be programmed in
increments of 15 nsec up to the frame period. There are gaps in the allowable exposure
times due to interaction between the readout circuitry and pixel reset in the MV13 sensor.
In the MV40 sensor the exposure time is even more restricted due to the rolling shutter
mode of operation. The Control FPGA will generate the exposure timing as close as
possible to the requested value.
Multi-frame edge-triggered mode effectively starts the camera into free-running mode for a
programmed number of frames after a delay of zero to about 64 seconds programmable in
15 nsec increments. The active edge of the trigger activates the time delay and the first
exposure starts after this delay. The camera can be re-triggered during active readout. If
re-trigger event occurs too soon to start the subsequent exposure after the programmed
delay, the next exposure will start as soon as possible thereafter. This prevents the effect
of running at submultiples of the trigger rate when the trigger rate exceeds the capability of
the camera.
Single edge-triggered mode is the same as asynchronous multi-frame edge-triggered
mode with the frame count set to 1.
External exposure mode starts exposure as soon as possible after the active-going edge
of the trigger and stops exposure as soon as possible after the inactive-going edge of the
trigger. For the MV13, this provides accurate exposure timing based on the trigger pulse
