JAI CV-A50, CV-A60 operation manual Long Time Exposure Mode, Long time exposure. Field accumulation

CV-A50 / CV-A60

6.8. Long Time Exposure Mode

The exposure time is the interval between 2 ext. VD pulses sent to the VD input of the camera (Pin No. 7 of the 12-pin Hirose connector). The exposure starts after input of the first ext. VD pulse, and ends after the next input of the next ext. VD pulse, which again starts a new exposure. The long time exposure is a continuous process where each external VD will synchronize the camera, stop on exposure, start a new exposure and read out the previous accumulated signal. The exposure time can be selected in intervals of complete vertical timing periods (525H for EIA and 625H for CCIR).

To use this mode:
Set function:	Trigger mode to “Long time exposure”	TR=4
	Accumulation to “Field” or “Frame”	FR=0, F=1
	Scanning to “Interlaced”	SC=0
	Shutter to “OFF”	SH=0
	Polarity and other functions
Input:	Ext. VD to pin 7 on 12 pin connector.
	Ext HD to pin 6 on 12 pin connector.

Fig. 23. Long time exposure. Field accumulation.

Fig. 24. Long time exposure. Frame accumulation.

Important notes on using this mode:-

•Exposure time range is 1/30 sec. to ∞. However, it is recommended not to use exposure over 2.0 sec. This is because visible dark current noise may appear on the video signal due to the long time exposure of the CCD image sensor.

•Ext. HD signal (TTL 2.0~5.0V) has to be input continuously.

•See Fig. 16 for the phase relationship between ext. HD and ext. VD pulses

•The EEN pulse is not provided when using this mode.

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