Microscan Quadrus EZ, Руководство пользователя, Страница: 343 / 366

Quadrus EZ Reader User’s Manual
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Appendices
External Edge—Allows a read cycle to be initiated by a trigger signal from an object
detector when it detects the appearance of an object (rising edge). The read cycle ends
with a good read, a timeout, or a new trigger.
External Level—Allows a read cycle to be initiated by a trigger signal from an object
detector. The read cycle ends when the object moves out of the detector’s range.
Falling Edge—A change of state (to inactive) associated with a level trigger in which Fill
Factor—Percentage of pixel area used for light collection.
Firmware—Software hard-coded in non-volatile memory (ROM).
Fixed Code Length—Increases data integrity by ensuring that only one symbol length will
be accepted.
Focal Distance—In camera-based vision, the distance from the front of the camera to the
object being viewed. (In optics, the distance from the lens to the focal plane.)
Focal Plane—Usually found at the image sensor, it is a plane perpendicular to the lens
axis at the point of focus (-).
Focus—The point at which rays of light converge for any given point on the object in the
image. Also called the focal point.
Frame—The total area scanned in an image sensor while the video signal is not blanked.
Frame Grabber—A device that interfaces with a camera and, on command, samples the
video, converts the sample to a digital value and stores that in a computer's memory.
Front End System—The object, illumination, optics and reader blocks of a vision system.
Includes all components useful to acquire a good image for subsequent processing.
FPGA—A field-programmable gate array.
Gain—The amount of energy applied to the pixel gray scale values prior to output,
expressed in dB; optimal signal strength.
Good Read—A decode. The successful scanning and decoding of the information
encoded in a bar code symbol.
Gradient—The rate of change of pixel intensity (first derivative).
Gray Scale—Variations of values from white, through shades of gray, to black in a digi-
tized image with black assigned the value of zero and white the value of one.
Half Duplex—Auxiliary port data is sent directly to the host and displayed on the auxiliary
port screen.
Histogram—A graphical representation of the frequency of occurrence of each intensity
or range of intensities (gray levels) of pixels in an image. The height represents the num-
ber of observations occurring in each interval.
Host—A computer, PLC, or other device that is used to execute commands and process
data and discrete signals.
Image—Projection of an object or scene onto a plane (i.e. screen or image sensor).
Image Processing—Transformation of an input image into an output image with desired
properties.
Image sensor—Array of pixels on a CCD or CMOS sensor.
Initialize—Implement serial configuration commands into the reader’s active memory.