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(4-3) Strobe signal output circuit
The internal output circuit is shown in the right figure.
● Conventional cameras used the strobe signal (STRB) as
the exposure timing signal only. In this equipment, this can
be switched between OFF, STRB signal (continuous &
asynchronous) and Busy signal(asynchronous) by setting.
This setting can be changed on the configuration menu
(Operation Mode Setting Group 3) or by way of rewriting the
configuration register with serial communication command.
The default setting is OFF (no strobe signal).
This equipment is capable of outputting the strobe signal even in the continuous shutter mode as well as in the
asynchronous shutter mode when the setting is changed to output the strobe timing signal(STRB).
[Explanation] Usage of strobe signal in continuous shutter mode
Shutter exposure time
Continuous lighting
In the continuous shutter mode, only the incoming light for the time matching the exposure time of the camera is valid.
Accordingly, when a lighting unit is used in the continuous lighting mode, the lighting during the time other than this exposure time
period would be wasted.
Since this equipment is capable of outputting strobe signal (STRB) even in the continuous shutter mode, this output is used as a trigger
signal to control a LED light or other lighting units that can be turned on and off at high frequencies, which helps eliminating the lighting
during the useless lighting time.
The following benefits are derived from this type of lighting control:
The consumption of the power to a light can be saved by way of lighting only during the valid time for exposure.
●
The occurrence of smear is reduced because no light enters any time other than the exposure time periods.
●
(Note) When the strobe signal is used in the continuous shutter mode to make ON/OFF control on a lighting source unit,
the following must be taken into consideration:
Wherever possible, use a strobe lighting unit or others that are equipped with a power source separated from that
of the camera (electrically isolated power source) and a trigger input terminal (photo coupler input, etc.). If a
lighting unit that shares a power source or a ground circuit with the camera is turned on or off by the strobe signal,
the image output from the camera may have noise due to the influence of the fluctuation of the power supply
voltage or change in the electric potential that occurs at the ON/OFF timing.
Even when the insulation aforementioned is applied, the electromagnetic induction may lead to the occurrence of
noise on the image signal if the electric current of the lighting unit to be control is large. In this case, a measure
must be introduced to reduce electromagnetic induction noise arising from the lighting unit.
(4-4) Test pattern display function
When initially connecting this camera to an image capture board, the use of the test pattern display
function of the equipment makes it easier to confirm that the output timing of the camera and the
details of the signal connection match the particulars of the capture board.
When the test pattern function is set to be ON, the image sensor outputs the test pattern in place of
pictures as shown on the right.
As for this pattern, a numerical value of 1 is simply added in an incremental manner for every
horizontal pixel, and a saw-tooth profile is shown in the range from the numerical value of 0 to 1023.
(Note) In the data, a numerical value of 1 is incrementally added for every horizontal pixel in the
range of 0 to 1023 for the case of 10 bit output, and in the range of 0 to 255 for the case of 8
bit output.
(Note) The value does not start with 0 at the edge of the effective image area.
(Note) The output values of the test pattern are not affected by the values of the gain setting or offset setting of the
camera.
The default setting is OFF. This setting can be changed on the configuration menu (Operation Mode Setting Group 4) or
by way of rewriting the configuration register with serial communication command.
[Procedure for switching test pattern output ON/OFF]
(1) Start up in the Setting group 4.( Set the mode switch to the position "D", keeping the power to the camera off. Then
turn on the power of the camera while turning and keeping the UP/DOWN switch lever to the either of upper or lower
position).
(2) Return the UP/DOWN switch lever to the neutral position when the response sound of "pip-pip" is heard
(3) Change the position of the mode switch to "2" after confirming that LED indicator flashes in orange.
(4) The test pattern display gets ON by stroking UP/DOWN switch upward and gets OFF by stroking that downward.
(5)
Switch to OFF when Test pattern is not necessary anymore. Since the setting of the test pattern output is
automatically saved, the test pattern will be output with last setting when the power is reapplied from next time.
Exposure
Valid
STRB signal
F rom
i nte rna l c ir c ui t
＋５ Ｖ
OFF
STRB
BUSY
74VH C T04A
or equivalent）
(
Fig. 4-5. Strobe signal output circuit
Useless lighting time
- 8 -
K09821;8/37
１ ０ ０Ω
Ｓ Ｔ ＲＢs i gn al out put
6.8 ZD
( 11 )pi n o f Ca mer a c onn ec t or
Exposure
Valid
Useless lighting time
1023
0
Test patte rn a nd hor izon tal pr ofil e
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