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(5-4) MGC gain setting value
●
Gain variable amplifier and integrated gain
The image signal output from CCD is amplified inside the
camera through the following variable gain amplifier and
then through the fixed gain amplifier before being input into
the A/D converter.
The left block chart shows this flow.
(Note) The gain value (dB) described here is the one based on the CCD output (0 dB) as the baseline.
●
Correlation between MGC gain setting value and MGC gain
The MGC setting value of this equipment is controlled
by giving 24 to 224.
The correlation between this setting value and the
MGC gain (integrated gain including the gain of the
variable gain amplifier and that of the fixed gain
amplifier) is shown in the right graph.
(Note) When the CCD element receives excessive light
with a low gain value of the amplifier, the signals
of the nonlinear area of the CCD element and
the preamplifier are output at the high
brightness area due to the restriction of the
dynamic range of the CCD light receiving
element.
In this state, unnatural image (Note below) may
appear in the neighborhood of the saturating
signal area of the image due to the
characteristic of the nonlinear area. This
phenomenon, which is associated with the
saturation characteristic of the CCD element, is
not a failure arising from the camera.
To eliminate this phenomenon, reduce the
amount of light by stopping down the lens and
newly set a higher gain value. Then, the output
signal from the CCD element at the saturating
area will be appropriately saturated into a white
level for the output.
(Note) The above described unnatural image
represents the following states:
●
Black and white look inverted at the saturating area.
●
The outline of the saturating area is blurred.
●
The saturating area slightly shifts upward or downward.
●
The brightness value of the saturating area does not reach 1023.
(5-5) Program page setting
The FC series cameras incorporate nonvolatile memories
and various operation mode settings and level settings can
be stored in them.
The setting items are stored in the virtual pages (hereinafter
referred to as “program pages”) inside the camera.
This camera has 6 program pages of “A”, “B”, “C”, “D”, “E”
and “F” (right figure).
The camera starts operating according to the various
settings stored in the relevant page when the mode switch is
at any one of the positions from “A” to “F” at the time of
power-on.
The camera starts operating according to the settings stored
in the page “A” when the mode switch is at any position other
than those from “A” to “F” at the time of power-on.
1 to 16 dB
GAIN
3 dB (Fixed)
A/D
Preamplifier
Variable gain
amplifier
Fixed gain amplifier
CCD
Integrated gain
MGC setting
4 to 19 dB
Program page F
Program pages from B to E
Program page A
[Electr onic shutter operati on mode]
•
Shutter system = Continuous/as ynchronous
•
Type of shutter speed = High speed/ l ow speed
•
Electronic shutter table = Correspondence
rel ation between shutter switch and shutter
speed
[Other operation m odes]
•
Scanni ng s ystem = Nor mal/par ti al -scan
[Level s etting]
•
Gain setting val ue = (Saved as the internal val ue)
•
Offset = ( Saved as the internal value)
Fig. 5-3 Conceptual diagram of program page
MGC GAIN CODE
M
G
C
G
A
IN
(d
B
)
6
12
18
24
0
20
40
60
80
A0
C0
E0 (hex)
32
64
96
128
160
192
224(dec)