JAI CV-M30 operation manual Pulse Width Control Mode

CV-M30

6.3.2. Pulse Width Control Mode

The pulse width control mode will only work in non-interlaced field accumulation mode. The exposure is controlled by the low period of the ext. trigger pulse. The CV-M30 starts the exposure at the first HD pulse after the falling edge of the ext. trigger pulse. The exposure ends at the first HD pulse after the rising edge of the ext. trigger. The Shutter can be controlled to be within the range from >1H (>32 usec.) to <1000H. The AC coupling causes the upper limit.

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 trigger low time. It is the limit for the field rate.

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 mode.
	SW1-4 to OFF and SW1-6 to ON for non interlaced mode.
	SW2-1 on PK8212 board ton ON for Pulse Width Control mode.
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 Pulse Width Control Mode.

1.Pulse width control 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. 8. 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 pulse width should be >1H (>32 usec.) to <1000H.

3.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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