JAI CV-M50 operation manual Long Time Exposure Mode, EIA Ccir

CV-M50

6.3.4. Long Time Exposure Mode

The Long time exposure will work in 3 modes:

1.Interlaced with field accumulation.

2.Interlaced with frame accumulation.

3.Non-interlaced with field accumulation.

The exposure time is the interval between 2 ext. VD pulses sent to the camera VD input. Each ext. VD pulse will reset and restart the internal VD in the camera as for ext. HD/VD input. So the camera is synchronized to the external HD/VD supply after each VD input.

An exposure starts after input of an external VD pulse, and ends after the next input of ext. VD, which again starts a new exposure.

The long time exposure is a continuous process where each external VD will synchronize the camera, stop an exposure, start a new exposure and read out the previous accumulated signal as interlaced or non-interlaced fields.

The exposure control can be done by feeding every Nth VD pulse from the external HD/VD supply to the camera. N is the wanted exposure time in number of fields. This is typically done in the frame grabber PC.

The range for long time exposure is from 1 V (a single field) to ∞. However the dark current signal will increase by longer time, so >2 seconds are not recommended at normal ambient temperature.

To use this mode:

Set:	SW1-1, 2 and 3 to OFF
	SW1-4 to OFF for normal shutter.
	SW1-5 to ON for frame accumulation or OFF for field accumulation.
	SW1-6 to OFF for 2:1 interlaced or ON for non-interlaced.
	Jumper JP6 on PK8057 to CLOSE
Input:	Ext. VD pulses with the exposure interval to pin 7 on 12 pin multi connector.
	Ext. HD to pin 6 on 12 pin multi connector.
	75 Ohm termination is done with SW2-1 and SW2-2 on PK8057 board.

The timing for the external VD interval has to be as follow. (V is the time for a single field)

Interlaced with field accumulation.	1 V or more
Interlaced with frame accumulation.	2 V or integral number of 2V
Non-interlaced with field accumulation.	2 V or more

Note:The external HD/VD sync. generator, which supply the ext. VD an HD signals should follow the scanning standard for the camera setting.

	EIA	CCIR
Interlaced and field accumulation.	1 V = 262.5 H	1 V = 312.5 H
Interlaced and frame accumulation.	2 V = 525.0 H	2 V = 625.0 H
Non-interlaced and field accumulation.	2 V = 524.0 H	2 V = 624.0 H

Refer to Timing Chart and Cautions on next page.

Detailed switch and jumper setting is described in “7. Mode Setting”.

For connections see 5. “Pin Assignment”.

- 12 -