Erhardt+Leimer OL 80 - 5.6 Determining the background; 5.7 Mount support roller

BPage10 BEA--220265-EN-04
CCDarraycameraOptoLineOL80..
Background
Background
Web
Lighttransmitterassemblywith
frontlightingprinciple
Whenusingfrontlightingthefollowingshouldbeobserved:
- whenscanningtheedgesoftransparentwebs,mountthelight
transmittersothatthemirrorsurfacereectsthelightsentfrom
thetransmitterintothecamera(seeillustrationaboveleft).
- whendetectinglinesandcolourcontrastsontransparentand
opaquewebs,mountthelighttransmittersothatadiffusereec-
tionisproduced.Surfaceglareisavoidedandaclearimageis
produced(seeillustrationaboveright).
 When frontlighting, please ensure that the light transmitter is
not in the camera visual range.
Auniformcontrast-freedarkbackgroundisrequiredforfrontlighting.
Youmayhavetomountamattblackpanelbehindtheweb,inthe
cameravisualrange.Thisoptimumcontrasttothewebguarantees
efcientwebedgescanning,inuencesfromexternallightsources
areavoided.
Itmustbeguaranteedthatthewebdoesnotformfoldsorcreases
andthattheedgesdonotturnupasotherwisethelightisreectedat
adifferentanglebythewebandnolongercapturedbythecamera.A
supportrollercanbemountedifnecessary.
Withfront-lightning,thesupportrollershouldbemountedoutsidethe
camerameasuringrange,eitherbeforeorafterthecamera.Seeil-
lustrationonleft.
5.7 Mount support roller
5.6 Determining the back-
ground
Background
Supportroller
Example:frontlighting
Supportrollermountedafterthecamera