Pulnix TM-4000CL Series Manual do Utilizador descarregar pdf (Página 2)

TM-4000CL Progressive Scan High-Resolution Shutter Camera

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 2k CCD operating at 40MHz pixel

clock, the noise level is around 50 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-4000CL uses a 1.2” CCD with 7.4 µm x 7.4 µm pixel

and two-phase vertical shift register structure. The well capacity is

42,000 electrons. The theoretical dynamic range is 42,000:50 =

840:1 (58 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, it uses less than 1/5 of the

full 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-4000CL has a built-in LUT (look-up table) for dynamic

range control.

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 look-up table has two knee points (variable gamma

selection) that allow the 10 bits to be segmented into three

regions. The look-up table selection can be made either by

variable knee curve or by direct input of the knee coordinates.

Scan Mode

Full Progressive Scan

Normal scanning mode for the TM-4000CL is 2048 x 2048

pixels. The standard speed with dual-channel output is 15

frames/sec at the pixel clock of 40.0 MHz*. Unlike an interlace

scan camera, the TM-4000CL reads every line from top to bottom,

resulting in all lines being obtained per captured image frame with

electronic shutter.

Partial Scan

1000 lines and 500 lines partial scan is selectable. It outputs

image center of 1000 lines and 500 lines. At 1000 lines the frame

rate is 15/30 frames /sec. At 500 lines, it is 30/60 frames /sec.

Dual Tap Output

TM-4000 has built-in line buffers to select channel B output

direction. CCD output is split into two channels. The left half

outputs data from 1 to 1024 (ch.A) and the right half outputs from

2048 to 1025 (ch.B). The internal line buffer corrects the right half

(ch.B) output to start from 1025 to 2048 so that frame grabber

does not have to convert the pixel orders. The ch.B output

direction is selectable.

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100

120

200

400

600

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

Vsub = 8 V

CCD dynamic range utilization

256

224

192

160

128

128 256 384 512 640 768 896 1024

Knee

Ta ble

LUT #7

LUT #3

LUT #5

LUT #4

LUT #6

LUT #0

Left Knee

(X1, Y1)

84 224

56 224

80 160

60 160

40 160

96 192

48 192

112 224

Right Knee

(X2, Y2)

1024 256

Note: The second knee point on the built-in LUT defaults to position (1024, 256).

To reposition this point, click on it and drag it to a new location.

LUT #1

LUT #2

Linear image:When PCB surface is visi-

ble, 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.

1024

1025

2048

CH. A output

CH. B output

2047

2046

LDV

Data Clock

1024

1025

1025 1026 1027

2048

2047 2046

Ch. A Data

Ch. B Data

w/o conversion

with conversion

(Note: Camera Link data strobing is positive edge strobe)

Enable

CCD output

1 2 3 4

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