JAI CV-M30 - Manual (Page 8)

CV-M30
6.3.1. Edge Pre-select Mode
The edge pre-select mode will work in non-interlaced and field accumulation mode with partial
scanning and double speed. The CV-M30 starts the exposure (= accumulation of photoelectric
charge) at the first HD pulse after the falling edge of the ext. trigger pulse. The exposure ends
after the time set by the 3 shutter switches SW1-1 to SW1-3. The accumulated signal will be
read out as a single field before a new trigger can be applied. The interval between trigger
pulses must be longer than the time for 1 field + the shutter time. It is the limit for the field
rate. For partial scanning the longest shutter time are not available.
In this mode, the EEN (Exposure ENable) pulse and WEN (Write ENable) pulses are generated and
output from the camera. The EEN pulse indicates the exposure time and can be used to control
the illumination such as strobe light. The WEN pulse indicates the time period of the effective
video signal output, and is useful for the timing and interfacing of external devices such as
frame grabbers.
To use this mode
Set:
SW1-7 to ON for ext. trigger shutter
SW1-4 to OFF and SW1-6 to ON for non interlaced mode
SW2-1 on PK8212 board ton OFF for Edge Pre select mode
SW1-1, SW1-2 and SW1-3 to shutter speed
Input: Ext. trigger to pin 5 on 6 pin connector or pin 7 on 12 pin connector.
Ext. HD to pin 6 on12-pin connector. (If used).
75 Ohm termination is done with SW1-1 (HD) and SW1-2 (Trig) on PK8212 board.
Refer to “6.5.Timing Chart”.
Detailed switch setting is described in “7. Mode Setting”.
For connections see “5. Pin Assignment”.
Cautions in the Edge Pre-select Mode.
1. Edge pre-select mode is effective in non-interlaced, field accumulation mode. Double speed
and partial scan can be used.
2. The exposure start may delayed up to 1H max., when the falling edge of ext. trigger pulse is
not synchronized with the falling edge of ext. HD signal. To avoid this 1H delay and jitter,
the falling edge of the trigger pulse should be synchronized with the HD pulse as shown
below. It can be the ext. HD input or the Internal HD output.
Fig. 7. External trigger and HD relations
3. The ext. trigger input is 75 Ohm terminated as factory setting. The voltage level of the ext.
trigger has to be 4.0 Vp-p ± 2.0 V. The duration should be more than 1 H negative going. >32
µsec. and < 1000H. The input is AC coupled.
4. If the ext. HD input and ext. trigger input are from a TTL source, set SW1-1 (HD) to OFF and
SW1-2 (ext. trigger) to OFF for non-terminated.
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