Exposure Time Control - Photon Focus MV1-D1280 Series User Manual

5 Functionality

5.2.4 Exposure Time Control

In the external trigger mode the rising edge of the trigger pulse starts the camera states
machine, which controls the sensor and optional an external strobe output. Fig. 5.12 shows the
detailed timing diagram for the external trigger mode.
t
d - i s o - i n p u t
t
j i t t e r
Figure 5.12: Trigger timing diagram
The rising edge of the trigger signal is detected in the camera control electronic which is
implemented in an FPGA. Before the trigger signal reaches the FPGA it is isolated from the
camera environment to allow robust integration of the camera into the vision system. In the
signal isolator the trigger signal is delayed by time t
FPGA which leads to a jitter of t
can be configured by a user defined value via camera software. The trigger offset delay
t results then from the synchronous design of the FPGA state machines and from to
trigger offset
requirement to start an exposure at a fixed point from the start of the read out of a row. The
exposure time t
exposure
The trigger pulse from the internal camera control starts also the strobe control state machines.
The strobe can be delayed by t
the customer via software settings. The strobe offset delay t
synchronous design of the FPGA state machines. A second counter determines the strobe
duration t
strobe duration
isolated from the camera electronic which leads to an additional delay of t
gives an overview over the minimum and maximum values of the parameters.
46 of 103
t
t r i g g e r - d e l a y
t
t r i g g e r - o f f s e t
t
e x p o s u r e
t
s t r o b e - d e l a y
t
s t r o b e - o f f s e t
t
s t r o b e - d u r a t i o n
t
d - i s o - o u t p u t
. The pulse can be delayed by the time t
jitter
is controlled with an internal exposure time controller.
with an internal counter which can be controlled by
strobe delay
(strobe-duration). For a robust system design the strobe output is also
A x t e r n a l t r i g g e r p u l s e i n p u t
t r i g g e r a f t e r i s o l a t o r
t r i g g e r p u l s e i n t e r n a l c a m e r a c o n t r o l
d e l a y e d t r i g g e r f o r s h u t t e r c o n t r o l
i n t e r n a l s h u t t e r c o n t r o l
d e l a y e d t r i g g e r f o r s t r o b e c o n t r o l
i n t e r n a l s t r o b e c o n t r o l
e x t e r n a l s t r o b e p u l s e o u t p u t
. This signal is clocked into the
d iso input
results then from the
strobe delay
which
trigger delay
Table 5.8
d iso output
MAN061 12/2018 V1.3