K12703 ; 8/43
- 8 -
● LED indicator
for
Vinit signal monitoring
When this camera is set in the asynchronous shutter mode, the LED
indicator on the rear panel of the camera lights up in red for one shot in
response to the input of the external trigger signal (Vinit signal).
This allows the user to confirm the state of signal input.
The LED lights up in red for a certain period of time (for about 100 ms)
each time upon detection of a trailing edge of the trigger signal. If a
following trigger signal is input within this period, the lighting time of the
LED will be retriggered and extended.
Since the lighting of the LED responses only to the trailing edge of the
trigger input, it lights up only once for 100 ms even if the trigger input
pulse duration is longer than the one shot time of period.
● Setting of various asynchronous shutter modes
Set the parameters and others in accordance with the following table:
Table 4-1 Setting of various asynchronous shutter modes
Asynchronous shutter mode
PWC
Shutter switch
Remark
Preset shutter (PWC=DISABLED)
DISABLED
1 to 9
Preset shutter (PWC=ENABLED)
ENABLED
1 to 8
Pulse width control
9
Shutter switch = 1 to 8: same as preset shutter
(Note) When shutter switch is 0,
“Continuous image output(no shutter)” is applied for the all.
(Note) For setting methods for the respective parameters of
“PWC” and others → See “ How to set operation mode”.
● Recommended timing of asynchronous shutter trigger signal (Vinit signal) for preset shutter/pulse width control
For the case of preset shutter mode, the negative logic pulse is applied
within the width range from 1 H (1 horizontal synchronous interval) to 40H
as described below.
For this case, the exposure operation starts in synchronization with the
trailing edge of the applied pulse.
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 trailing edge of the internal HD
pulse, 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]
1H
Tvinit
40H
(The exposure time is independent of the Vinit width.)
1H=1 horizontal scan time
[For the case of pulse width control mode]
(Where PWC=ENABLED, shutter switch = 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 Vinit signal timing
(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 image sensor 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.
● Example of drive circuit for Vinit input circuit
Cam era
con nector
１００Ω
Vinit1 IN
［Inside of Camera］
４．７Ｋ
to internal circuit
Ｔ Ｃ７４ＬＶＸ１４
（ or equivalent）
７５Ω
［Example of user circuit］
７４ＡＣ０４or
others
ＶＣＣ
１０Ｋ
VCCis +5V or +3V
３．３Ｖ
３．３Ｖ
６
４７ｐ
3.9ZD
CC1（Vinit2）
input
Vinit2 polarity setting
N EGA TIV E
PO S ITIV E
*
The Vinit signal should not include unnecessary noise components such as chattering.
[Input voltage range ]
H level
2.5 to 5.5V
L level
-0.5 to 0.5V
● Polarity reversal of Vinit2 input
The input polarity of the trigger signal (Vinit2) to be applied via CC1 of Camera Link can be inverted.
Some capture boards may have the polarity of the trigger signal input from CC1 that is fixed to positive logic (L level at
normal/H level at active), which is not compatible with the trigger signal of negative logic input (factory preset polarity
of this equipment). In this case, the input polarity of the trigger signal (Vinit2) via CC1 can be inverted to change from
negative to positive logic by the setting of the camera.
→ Refer to “(6-3) How to set operation mode” for the specific setting method.
(Note) The setting of the polarity reversal is valid only for Vinit2. The input polarity of Vinit1 is always negative logic
regardless of this setting.
Fig. 4-2. LED indicator
Fig. 4-4. Vint circuit
MEDI UM
POW ER
BASE
Operation indicatorＬＥＤ
L E D lig h t s u p in re d in r e s p o n s e
t o t r ig g e r s ig n a l in p u t ( V in it ) .
