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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 N
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.
Interlaced with frame accumulation.
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.
Interlaced and field accumulation.
Interlaced and frame accumulation.
Non-interlaced and field accumulation.
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".
CV-M532
th
VD pulse from the external HD/VD supply to the
1 V or more
2 V or integral number of 2V
EIA
1 V = 262.5 H
2 V = 525.0 H
2 V = 524.0 H
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