K11414;7/20
- 7 -
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Recommended timing of asynchronous shutter
trigger signal (Vinit signal) for preset shutter/pulse width control
For the case of the pulse width control exposure mode, numeric
value of the L level interval of the input Vinit pulse (shown as
Tvinit in the figure) is retrieved in synchronization with the HD
trailing edge inside the camera, and the integer multiple number
of H (1 horizontal synchronous interval) that is closest to the
retrieved Vinit pulse duration is transmitted as nH to the inside of
the camera. Then the shutter speed is determined in response
to the time nH.
Vinit
Tvinit
[For the case of preset shutter mode]
2H
≤
Tvinit
≤
20H
(The shutter speed is independent of the Vinit width.)
[For the case of pulse width control mode(shutter SW=9)]
nH
≤
Tvinit <(n+1)H (n is 1 or larger integer.)
(This is the pulse width where shutter exposure time =nH)
Fig. 4-3 Recommended Vinit signal timing waveform
(Note) In the pulse width control, the shutter exposure time is almost equal to the integral multiple number of the horizontal
synchronous time (H) that is closest to the Vinit pulse duration. More specifically, however, the shutter exposure time is
indefinite for the time period corresponding to 1H width in the case of normal external trigger input (or the case where the
Vinit signal is not in synchronization with the horizontal synchronous timing of the camera)
→
Refer to the timing chart
described in another section for the details.
(Note) When the shutter exposure time is too long in the pulse width control mode, the S/N ratio of the image will be degraded due
to the reduction of dynamic range of CCD, accumulation of thermal noise components of CCD imaging device in proportion
to the shutter speed and other factors. Therefore, if a long exposure time is employed, it is recommended to conduct
experiments using realistic exposure times in actual conditions to check for the appropriateness.
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Example of drive circuit for Vinit1 input circuit
６
Camera
connec tor
１０ ０Ω
Vi ni t IN
Ins ide o f c am era
２２Ｋ
To in te rna l cir cui t
ＶＨＣＴ１ ４
（or equivalen t）
１５０Ω
２ＳＣ３ ３１１
or others
［ I n c as e of Tr a n si s t or ］
［ I n c a s e o f I C ］
Ｏ．Ｃ．
ＳＮ７ ４０６
or other s
ＶＣＣ
１０ Ω
１０Ω
３３Ｋ
１０ Ｋ
５Ｖ
ＶIH＝２ ．０Ｖ
ＶIL＝０ ．８Ｖ
ＶＣＣ is +5V or+3V
１５０Ω
ＶＣＣ
t o ６
５Ｖ
* The Vinit signal should not include unnecessary
noise components such as chattering.
(4-3) Input of external synchronous trigger signal(Ext-HD/VD)
●
How to input external synchronous trigger signal
When more than one cameras are used in synchronization state, it is necessary to input external synchronous signal
(Ext-HD/VD signal) from user side equipment. When it is needed to synchronize horizontal timing, input HD signal.
Input HD and VD signals to synchronize both horizontal and vertical timings.
(Note) Note that the delay jitter may occur between externally supplied HD signal and HD signal within the camera, when
horizontal operation timing is synchronized by external synchronous signal,
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Recommended external sync signal
１Ｈ ＝３１ ．２ ５μse c
９Ｈ
１ Ｖ（ １０６ ８Ｈ ）
Ｅ ｘ ｔ － Ｈ Ｄ
Ｅ ｘ ｔ － Ｖ Ｄ
２ ．７ ４μs ec
±２ μsec
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Example of external sync input circuit and drive circuit
(4-4) Other input/output circuit
●
Strobe signal output circuit
+5V
100
Strobe signal: Pin 11 of
camera connector
From internal
circuit
74HC125
(or equivalent)
Camera
c onnector
I nside the c amera
To int ernal circuit
１０ Ｋ
Ｔ ｒ
１ ０Ｋ
４ ． ７ Ｋ
5
V
5
V
10
µF
１ ００ｐＦ
７ ５Ω
Example of user circ uit
74AC04 or
ot hers
5V
Ext-VD
7
Ext- HD
9
２ ２ ０Ω