Pulnix TM-76 Manual de usuario Pagina 2

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TM-2016-8 Progressive Scan 2K x 1K Shutter Camera
www.pulnix.com
2
Dynamic Range Control
Typical interline transfer CCDs have fixed noise levels based
on dark current (thermal or KT noise), pattern noise, and
operating clock speed. Typically for a 2K x 1K CCD operating
at 20MHz pixel clock, the noise level is around 40 electrons.
The maximum capacity of the CCD charges is limited by the
well capacity at saturation. The range is limited by the structure
and the pixel size.
The TM-2016-8 uses a 1” CCD with 7.4 µm x 7.4 µm pixel
and two-phase vertical shift register structure. The well
capacity is 50,000 electrons. The theoretical dynamic range is
50,000:40 = 1250:1 (62 dB).
A typical CCD camera does not use the full dynamic range
due to the nominal gain and the output specification such as
RS-170. The typical CCD camera has its gain set at 16 to 22
dB and the RS-170 video level is 714 mV. Using 20 dB gain for
the calculation, CCD output is limited to 714/10 = 71.4 mV.
Since the CCD’s saturation voltage is 400 mV to 500 mV, the
system therefore uses less than 1/5 of the available dynamic
range.
Machine vision and outdoor applications cannot afford to
miss image information behind the saturation, which is why the
dynamic range adaptation is critical.
Programmable LUT and Knee Control
(patent pending)
The TM-2016-8 has a built-in LUT (look-up table) for
dynamic range control and preprocessing for feature
enhancements. At a specific gain setting, the offset (minimum
level... dark point) and A/D reference top voltage (maximum
level... saturation point) are set to 10-bit A/D input so that the
full dynamic range of the CCD is utilized at 10-bit references as
the input and the LUT output is converted into 8-bit to adjust
the gamma correction.
The 10-bit input is segmented into two or more regions by
the knee point settings as variable gamma selection.
LUT selections: (10 sets of standard knee values)
1 Variable knee curve
2 Direct input LUT
Scan Mode
Full Progressive Scan
The normal scanning mode for the TM-2016-8 is 1920 x
1080 pixels. The standard speed with single-channel output is
8 frame/sec at the pixel clock of 20.0 MHz. Unlike an interlace
scan camera, the TM-2016-8 reads every line from top to
bottom, resulting in all lines being obtained per captured image
frame with electronic shutter.
Two-Row Binning
This is a standard feature in the TM-2016-8. The camera
scans two rows together and outputs 1920 (H) x 540 (V) pixels
at 16 frames per second. Two-row binning is typically
implemented to increase the frame rate.
0
20
40
100
60
120
80
0
200
400
600
FL
Lens: F=5.6
Vsub = 10 V
Vsub = 12 V
Vsub = 14 V
Vsub = 16 V
Vsub = 18 V
CCD OUTPUT VOLTAGE
LUMINANCE
Blooming adj. = 13. 5 V
Digital saturation at 16 dB amp
Analog saturation at 20 dB amp
Max. Digital dynamic range at 3 dB amp
140
160
mV
Vsub = 8 V
CCD dynamic range utilization
255
224
192
160
128
96
64
32
0
128 256 384 512 640 768 896 1023
Knee
Ta ble
0
1
2
3
4
5
6
7
8
9
LUT #7
LUT #3
LUT #5
LUT #4
LUT #2
LUT #6
LUT #9
LUT #8
LUT #0
LUT #1
Left Knee
(X1, Y1)
84 224
56 224
80 160
60 160
40 160
96 192
48 192
112 224
Not Available
Not Available
Right Knee
(X2, Y2)
1023 255
1023 255
1023 255
1023 255
1023 255
1023 255
1023 255
1023 255
Linear image:When PCB surface is
visible, metal trace is saturated. If
the metal surface appears, then the
plastic surface is too dark.
Knee-controlled image:The upper is
LUT#6, the lower is #7. Both show
the full dynamic range with different
effects.
line 1
line 2
n
n+1
line 1+2
line 3+4
(2n-1)+2n
Two-row Binning
Progressive scan
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