Erhardt+Leimer OL 80 - Page 4

BPage4 BEA--220265-EN-04
CCDarraycameraOptoLineOL80..
Withthebacklighting methodthelighttransmitterispositioned
behindtheobjecttobescanned,asseenfromthescannedobject.
Inthecaseofnon-transparentmaterials,onlytheouteredgesare
detected.
Thefollowingappliesforbothmethods:
Whetheroneortwocamerasareusedtoestablishthepositionde-
pendsontheresolutionandwebwidthrequired(seeblockdiagram).
Whatisimportantisthatwhenwidthmeasuringorwebguidingwith
onecamera,bothwebedgesarealwaysinthecameravisualrange.
Whenwidthmeasuringorwebguidingwithtwocameras,oneweb
edgeeachmustbeinthecameravisualrange.
Thecenterpieceofthecameraisachargecoupleddevicewith2048
pixels.Theindividualpixelsconvertthelightshedintosignalvoltag-
es.Contrastchangesinthecamerameasuringrangesuchasaweb
orprintedlineonawebcauseachangeinthevoltage.The
cameracandetectupto30contrastchangesinitsmeasuringrange,
regardlessofwhetherthesearecausedbyoneorseveralwebs.See
g.onpage5.
Amaximumof8measuringvaluescanbeoutputonthebasisofthe
positionsrecorded.Ameasuringvalueisacontrastposition(e.g.the
webedgeposition)orthecenterbetweentwocontrasts(e.g.theweb
orlinecenterposition).
Thebuilt-inlightcontrollermakesthecamerapracticallyimpervious
tosoilingcausedbydustandenvironmentalfactorssuchassteamor
ambientlightuctuations.
Alldatatothecamera(camerasettings,measuredvalueselection)
andfromthecamera(measuredvalueposition,errormessages,
statusinformation)aretransferredviaaCANinterface.TheCAN
controllerisbuiltintothecamera.Thein-houseE+Lprotocolisused
ontheCANbus.Couplingtootherbusesorunitinterfacesises-
tablishedviaspecialinterfacemodulesthatcanbeattachedtothe
CANbus.Twokeysanda16-bitLEDdisplayareavailableforbasic
operatingfunctions,settingtheCANaddress,focusingthecamera
anddisplayingthemeasuredvalueposition.Furthersettingsareper-
formedviaanE+LcommandstationDO..orRT...
*CCD=Charge-Coupled-Device