8.Features
© 2023 China Daheng Group, Inc. Beijing Image Vision Technology Branch 76
Trigger Signal
Strobe Signal
Exposure Stage
T
fix_delay
T
exposure_delay
Figure 8-30 The exposure delay sequence diagram in overlaping exposure mode
When a hardware trigger signal is received to the sensor to start exposure, there is a small delay, which
is called the exposure delay and consists of four parts of time, as shown in Figure 8-31
T1: The delay introduced by the hardware circuit when the external signal passes through the optocoupler
or GPIO. The value is generally in the range of a few μs to several tens of μs. The delay is mainly affected
by the connection mode, driving intensity and temperature. When the external environment is constant,
the delay is generally stable.
T2: Delay introduced by the trigger filter. For example, if the trigger filter time is set to 50μs, T2 is 50μs.
T3: Trigger delay (trigger_delay), the camera supports trigger delay feature. If the trigger delay is set to
200μs, T3 is 200μs.
T4: The sensor timing sequence delay, the internal exposure of the sensor is aligned with the row timing
sequence, so T4 has a maximum row cycle jitter. The value of each sensor is different. Some products
with large delay time (several hundred μs or more) have additional configuration time counted in T4.
Total exposure delay
Line0/2/3
T1
T2
T3
T4
Exposure start
Image readout
Figure 8-31 Exposure delay
The following table shows the total exposure delay time for each sensor.
T1 is calculated according to the typical delay (5μs) of line0. If it is line2, T1 can be ignored.
