JAI RM-4200CL, User Manual

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RM/TM-4200CL Series
18 Functions and Operations
When n =2079, the exposure time is maximum exposure time. If the exposure time is less than the time
available for one frame, the maximum trigger frequency is equal to 1/1 frame time. If the exposure time is
longer than the time available for one frame, the maximum trigger frequency is equal to 1/exposure time.
The minimum active period of the external trigger is 5 μ s.
Figure 22. Asynchronous Programmable External Trigger
3.3.5 Pulse Width Control Mode
In Pulse Width Control (PWC) Mode, the exposure time is controlled by the external trigger. When an external
trigger is applied, one discharge signal (Vsub) is generated right after the active edge of the trigger. The
exposure starts when the discharge signal is in the off state. The exposure is off following the trigger active
off. Exposure time is controlled by the pulse width of the external trigger. Because the CCD requires some
overhead from trigger active off to the transfer gate event, the actual exposure time is equal to:
Exposure Time = Pulse Width +20.6 μ s
Since one discharge signal (Vsub) is generated right after the active edge of the trigger, it is asynchronous with
LDV, and the discharge signal may happen during an active video transfer period, visible reset noise may show
in the current image. To avoid reset noise, the maximum trigger frequency in PWC mode should be less than 1/
(exposure time + one frame transferring time).
The minimum active period of the external trigger is 5 μ s . Theoretically, the maximum active period of the
external trigger is unlimited. But, since images obtained at 25
o
C are often very degraded due to thermal noise,
it is recommended the active period of the external trigger be no longer than one second.