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● Vertical timing: High speed/Pulse width control/Asynchronous shutter/Without H-reset
Ｖｉ ｎｉ ｔ
ＨＤ
（ Inte rnal hor izon tal
sync sig nal）
2 47× PCLK
E xpos ure time
C ame ra L ink
Ｆ ＶＡ Ｌ
Imag e ou tput
0.13
Ｓ ＴＲ Ｂ
0.13
Ｂ ＵＳ Ｙ
※In this chart,PCLK (*1)represents pixel clock and unless otherwise specified,
the time unit of the numerical valuesin this chart is horizontal sync time H(*2).
＊1 PCLK = 1/ 48.1 MHz = 2 0.8nS
＊2 H = 1 920 ×1 /48.10MHz = 3 9.92 uS
(Note) Strictly speaking, even if the same pulse width of Vinit is applied, the shutter exposure time differs for the period
corresponding to 1H width when the asynchronous shutter operation is executed in the pulse width control mode
(indefinite for 1H width).
Although an equal pulse width (value between 2Hs and 3Hs) is applied both for (A) and (B) in the figure below, the
phase relationship with the internal horizontal synchronous timing makes their shutter exposure times different from
each other: (A) shutter exposure time = 2Hs and (B) shutter exposure time = 3Hs.
Example of 1H difference with same Vinit signal
Vinit (A)
Vinit (B)
HD
(Internal horizontal
synchronous signal)
Because of the above reason, consideration must be given to the fact that the exposure time becomes indefinite for the
period of 1H shutter exposure time when a Vinit signal that is not in synchronization with the internal horizontal
synchronous signal (HD) is input from the user side. Some of the countermeasures to be taken are as follows:
(1) Use only with the shutter speed that do not have serious impact even if the shutter exposure time is indefinite for a
period of 1H.
••• No practical problem may be caused when the shutter exposure time is fairly long, say 100H width or longer because
the impact of 1H difference in exposure time over the signal level is relatively small.
(2) Use with H-reset mode.
••• The period where the exposure time is indefinite will remain within up to one clock as the internal HD timing is reset
(initialized) when the trigger signal is input
(Note) Since n does not have an upper limit, the exposure time can be prolonged to be more than one frame time. The
maximum exposure time to be employed, however, should be determined after implementing experiments based on
the conditions of the actual operation because a longer exposure time is accompanied by the degradation of S/N ratio
due to the accumulation of CCD thermal noises.
ｎ
E n d o f e x p o su r e ( S e n s o r g a t e )
12 50× PCLK
ｎ＋ ２
1
T he p er io d w he re i t is r e ga rd ed i nv al id to n ew ly i np u t tr ig ge r si gn a l.
1
2
1
2
3
1 250
12
（1230)
RG B
Ef f ec ti ve i ma ge d u ra ti on
B ay er
（
E ff ec ti ve i m ag e du ra ti on
(Shutter time: 2Hs)
(Shutter time: 3Hs)
- 31 -
）
1236
N11A27;31/37
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