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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 1ms as described below.
For this case, the exposure operation starts in synchronization
with the trailing edge of the internal HD pulse (the leading edge
of pixel clock in the case of H-reset mode) after and closest to
the trailing edge timing 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 (the leading edge of
pixel clock in the case of H-reset mode), and the integer multiple
number of H (1 horizontal synchronous interval) that is closest to
the retrieved Vinit pulse duration is transmitted as nH (the
integer multiple number of pixel clock in the case of H-reset
mode) to the inside of the camera. Then the shutter speed is
determined in response to the time nH.
(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). It is improved by being employed in "with H-reset" mode
→ 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
[Ex am ple of us er ci rc uit]
74A C04 or
others
V CC is +3.3V to +5V
* The Vinit signal should not include unnecessary noise components such as chattering.
[Input voltage range]
H level
2.5 to 5.5 V
L level
-0.5 to 0.5 V
*
he voltage of the terminal end on camera side is required to be within the above voltage range with the camera being connected.
T
(4-4) Strobe signal (STRB)
It is able to adjust the light emitting timing of external strobe light to the exposure time of the camera.
This signal can be output in the continuous shutter mode as well as in the asynchronous shutter mode.
● Strobe signal output circuit
The signal output terminal is used both for strobe signal (STRB)
and busy (BUSY) signal.
Select any of OFF (Default: H level fixed), STRB and BUSY in
configuration setting.
→ Refer to (7-5) Internal flag register and configuration register
The internal output circuit is shown in the right figure.
[output voltage range]
H level
3.0V (at 0mA) to 2.0 V (at 10mA)
L level
0.2V (at 0mA) to 0.5 V (at 10mA)
(!) The factory default is set to OFF for this camera.
It is required to set STRBC0 flag and STRBC1 flag when outputting STRB or BUSY signal,
Vi ni t1 I N
VCC
Camera
75
connector
Vinit
[For the case of preset shutter mode]
1H ≤ Tvinit ≤ 1ms
(The exposure time is independent of the Vinit width.)
[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)
Recommended Vinit signal timing waveform
3 .3 V
4 .7 k
4 7p
4
1 0k
100
6. 8V Z D
Tri gger si gnal v i a s eri al c om m unic ation
Tri gger si gnal of internal CPU ori gi n
From
in te rna l circui t
TC 7PA04 FU
o r equ iva len t
- 9 -
Tvinit
Ins i de of c am era
3.3 V
T C7SH 14 FU o r equ ival en t
To i nternal c i rc uit
+ 3.3V
+3.3V
100
M10510B;9/58
STRB sig nal
5
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