CV-M77
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6.4.2. Pulse Width Control Trigger
This trigger mode where the length of the trigger pulse determines the exposure time operates
in H non-reset mode. In H non-reset mode the trigger pulse and the HD signal are synchronized.
The exposure will start at the first HD pulse after the falling edge of the external trigger signal.
The exposure ends 0.5 H after the HD following the rising edge of the external trigger signal.
The trigger pulse must be longer than >1H (51
µ
sec) and shorter than 2000 H. To avoid jitter the
camera should be synchronized to an external HD. There are some requirements to the phase
between the ext. HD and the Ext. trigger. The falling edge of the trigger should appear in the
interval less than 8
µ
sec before the falling edge of the ext. HD and less than 2
µ
sec after the
falling edge of the ext. HD and the rising edge off the trigger should be fall in the interval 8
µ
sec
before the rising edge of the ext. HD and 2
µ
sec after rising edge of the ext. HD. (See figure
14.).
The EEN pulse indicates the actual exposure time.
The resulting video signal will start to be read out after the rising edge of the external trigger
signal. The WEN pulse indicates the start of valid video signal. Refer to timing charts for details.
A new trigger pulse must not be applied before the video read out has finished.
Mode setting and all other settings can be done via RS 232C control if rear switch SW1-10 is ON.
Mode setting and some other settings can be done by switch if rear switch SW1-10 is OFF.
For details: refer to “7. Configuring the Camera”.
To use this mode:
RS
SW1-
Set function: Trigger mode to “Pulse Width Control”
TR=2
1, 2 ON, 3 OFF
Polarity and other functions
Input:
Ext. trigger in on pin 5 on 6-pin con. (Or 11 on 12 pin). 4.0 Vp-p ±2.0V.
Ext. HD in on pin 6 on 12-pin connector. 4.0 Vp-p ±2.0V.
(If used).
Important notes on using this mode
•
The start of exposure will start synchronized to the internal H signal. The start may be
shifted max 1H. To avoid this shift (1H jitter), synchronize the camera to an external HD
and make sure that the trigger pulse aligns to the HD as shown in fig. 14.
•
The trigger pulse width should be >1H to <2000H.
•
A new trigger must not be applied before WEN is high.
Fig. 16. Vertical timing for Pulse Width Control
