Fairchild CAM 1250 User Manual

FEATURES
Single channel DC restored video
Small sealed enclosure
Remote operation (200 ft.)
Dynamic range 2000:1 minimum
Video data rates to 20 MHz
Precise sensor alignment
GENERAL DESCRIPTION
The CAM1X50 is a new generation of modular line scan cameras designed for incorporation into non-contact electro-optical measure­ment and process control systems. It is available in 512 1024, or 2048 pixel resolutions. Either single or dual video output channels, with or without DC restoration, can be supplied.
To operate the camera, two differential clock inputs and power are required. A DATA RATE clock with frequencies up to 20 MHz, will determine the video data rate. A LINE RATE clock controls the camera scan rate. The camera outputs a LINE SYC and DATA RATE differential signals for system interfacing and synchroniza­tion. These signal lines should use properly terminated, shielded twisted pair cabling for interconnection.
The camera requires power supply inputs of +5, +15 and -15 volts DC, internal regulators and filters provide noise immunity for the CCD sensor bias voltages. The 75 source impedance analog video is available on two coaxial connection as a single or dual (odd/even) channel of unrestored or DC restored video.
FUNCTIONAL DESCRIPTION
The circuitry within the camera is comprised of differential line driv­ers and receivers, timing control logic, a CCD linear imaging sen­sor, DC restoration, video combining, output gain and buffering.
CAM 1250 CAM 1350 CAM 1550 Line Scan Camera
sor input signal. The shift registers, clocked by the sensor φT input, deliver the charge to packets to a charge sensing amplifier where they are converted to proportional voltage levels. This synchronous stream of analog voltage levels is available on the sensor VIDEOOUTA and VideoOUTB pins.
CAMERA TIMING
The CAM1X50 is driven by supplying two differential RS-422 like clocks. The DATA RATE clock input will determine the video pixel output rate. The LINE RATE clock input controls the camera expo­sure and scanning rate. The frequency of the LINE RATE clock determines the camera scan rate, while the interval between suc­cessive clocks is the period for which the CCD has integrated light.
The camera outputs a LINE SYNC and DATA RATE differential sig­nals are used for system interfacing. LINE SYNC indicates the start of a new scan readout and always precedes the first active pixel by 23 clocks. The DATA RATE output is used as a digitize clock for an A/D to accommodate propagation delays due to long cable lengths.
IMAGE SENSOR
The Charge Coupled Device (CCD) used in the CAM1X50 is a high speed linear imaging sensor with 512, 1024 or 2048 photoelements. This device is a monolithic component containing a single row of 13µm x 13µm light sensing elements (photosites or pixels), two analog shift registers, and two output sense amplifiers that provide separate odd and even channels of sensor video.
Light energy detected by the photosites generate electron charge packets proportional to the product of integration time and incident light intensity. Periodically the collected photosite charge packets are transferred in parallel to their respective odd and even analog shift registers in response to a low to high transition of the φX sen-
The differential line driven clock inputs are converted into TTL levels within the camera by differential line receivers. Single ended TTL input clocks may be used at low data rates for short cable lengths if the negative clock input is biased at +1 volt. Operating the camera in this single ended mode is not guaranteed and camera performance varies with application implementation.
VIDEO
The two video outputs of the CCD sensor are DC restored on the dark reference cells that precede each scan line. The video is com­bined into a single channel of sequential pixels with a high speed video switch. The video is then inverted and amplified to provide a positive 1 volt peak signal at sensor saturation when terminated into 75Ω.
Fairchild Imaging, Inc., 1801 McCarthy Blvd., Milpitas, CA 95035 • (800)325-6975 • (408) 433-2500
CAM1X50
OPTICAL COMPONENTS
Each photosite element is 13µm (0.0051 inch) square. The total active array length is 6.65mm (0.26 inch), 13.3mm (0.52 inch), and
26.6mm (1.04 inch) for the CAM 1250, CAM1350, and CAM1550, respectively. The CAM1250 has a resolution of 512 elements. The CAM1350 has a resolution of 1024 elements. The CAM1550 has a resolution of 2048 elements.
All cameras are shipped with a removable Schott KG-1 infrared blocking optical filter inserted in the camera faceplate lens open­ing. The filter transmission convolved with the sensor spectral re­sponse yields a camera response from about 400nm to 800nm, with a peak response at about 600nm.
Cameras with a resolution of 512 or 1024 elements are supplied with a removable C lens mounting ring for use with standard 1 inch format CCTV lens. An Olympus or Nikkon Bayonet mount is pro­vided for the 2048 element CAM1550, which is specified in the camera order suffix code.
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Fairchild Imaging, Inc., 1801 McCarthy Blvd., Milpitas, CA 95035 • (800)325-6975 • (408) 433-2500
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